Elevator car brake units are known in different embodiments and are necessary for very different purposes of operating an elevator.
For a long time elevators were only equipped with mechanically operated elevator car brake units which were activated by the speed governor rope remaining behind the elevator car in the case of overspeed.
In recent times the requirements for elevator car brake units are constantly growing. There is the wish that elevator car brake units do not only manage cases of emergency such as overspeed or the free fall of the elevator car. Instead, it should also be possible to use them as a brake, for instance in order to reliably prevent unintended car movement of an elevator car standing in front of a landing from prematurely leaving the landing, for instance under the influence of the changing weight of its loading. Example of this can be seen in
Therefore, mechanically operated elevator car brake units are increasingly put aside and hydraulically operated elevator car brake units are used more often. Increasing demands are also made on these elevator car brake units. Recently, such elevator car brake units are also desired to dispose of a regulation of the brake force itself in the case of emergency. At least the elevator car brake units are to be as unobtrusively as possible during operation, they especially must not interfere with the driving comfort due to excessively abrupt application, and/or "gripping", or noise development during application.
Having said that, it is the object of the invention to propose an elevator with at least one hydraulic elevator car brake unit which allows an effective open or close loop control of the brake force applied by the elevator car brake unit.
This task is solved with the technical features of the elevator described in claim 1.
According to the invention, an elevator with an elevator car moving along guide rails up and down is provided. In most cases such an elevator car possesses no incorporated drive itself, but it is hoisted by means of at least one hoist rope and/or a hydraulic cylinder.
The inventive elevator comprises an open or close loop controlled hydraulic brake for decelerating the elevator car, in particular in case or irregular ride conditions as, for example, in case of overspeed.
The brake comprises at least one hydraulic actuator acting with its piston rod onto a brake pad. The words "acting onto" are preferably understood as "directly acting onto", however, in particular cases a broad sense of this words is appropriate. In such cases the words read "indirectly acting onto by means of a lever system". It can be sufficient that only one brake pad or brake lining of a pair of brake pads or linings is directly actuated by the piston rod. The piston rod is pre-stressed by a main spring unit in closing direction with a force that generates a brake friction. Usually this main spring unit generates the maximum brake friction determining the capacity of the brake. If a plurality of hydraulic actuators is provided, they will generate the maximum brake friction determining the capacity of the brake altogether.
The piston rod is connected to a piston which, depending on the hydraulic pressure prevalent in a first working chamber assigned to the piston, and, possibly, depending on the hydraulic pressure prevalent in a second working chamber assigned to the piston, completely or partly compensates the force of the main spring unit.
The speed with which the brake applies, and/or the resulting force with which the brake lining operated by the piston rod is pressed against the rail is open or close loop controlled by means of a hydraulic pressure source. The pressure side of the pressure source charges aforementioned first working chamber of the at least one piston with hydraulic fluid. The suction side of the pressure source is capable to suck hydraulic fluid from a second working chamber of the at least one piston.
Finally, an additional control line is provided that interconnects the first working chamber and the second working chamber. The actual flow rate of hydraulic fluid through the control line is determined by a control valve that is preferably designed as a remote control valve.
The working principle of the control line and the control valve determining the actual flow through it is as follows:
If the control valve is fully open, a pressure equalization between the first and the second working chamber can take place. Consequently the piston pre-stressed by at least one main spring unit can displace hydraulic fluid from the first into the second working chamber so that the brake applies. This will take place despite the fact that the pressure source may (dependent from the hydraulic layout) at the same time still tend to charge the first working chamber with pressurized hydraulic fluid while it tends to draw off (suck) synchronously hydraulic fluid from the second working chamber. The fully open control line will provide for pressure compensation also in regard to that.
If the control valve is fully closed, no pressure compensation via the pressure compensation line is possible between the first working chamber and the second working chamber. Due to the fact that the pressure source charges the first working chamber with pressurized hydraulic fluid while it draws off hydraulic fluid from the second working chamber (without any pressure compensation via the pressure compensation line being possible), the piston will be displaced into direction of the second working chamber until the piston has reached fully open position - that way the brake is released.
It is clear that the extent of pressure compensation between the first working chamber and the second working chamber can be open or close loop controlled by actuating the control valve that way that it is neither fully opened nor fully closed so that its actual hydraulic resistance determines the extent of the braking force applied.
A very preferred embodiment provides that the said at least one valve is a switching valve for exclusive on-off-service. Such a valve is no proportional valve. A proportional valve is characterized in that it controls the flow rate through its hydraulic path by bringing its valve body into a stationary position intermediate between "fully closed" and "fully opened" leaving free a defined hydraulically effective cross-section which corresponds to the desired flow rate. The aforementioned valve for exclusive on-off-service is characterized in that it possesses a valve body that cannot adopt a stationary intermediate position between "fully closed" and "fully opened", at least as long as energized. The only stationary positions that may be adopted (depending on the particular design) by the valve body are the positions "fully closed" or "fully opened".
The flow rate through the hydraulic path is controlled by repeated switching of the valve body back and forth between "open" and "close" - preferably this switching back and forth should take place repeatedly within one second. Ideally, the switching frequency amounts to 15 Hz or more.
It is advantageous if the valve for exclusive on-off-service is a seat valve, i.e. a valve having a valve seat that comes into sealing (fluid tight) contact with the valve body if the valve is closed.
The valve for exclusive on-off-service is preferably controlled by pulse width modulation, or frequency, or a mixture thereof.
There are two different modes for accomplishing said switching back and forth:
The first mode is to switch that way that the valve body comes at rest on its valve seat before switching over so that the valve body starts to move in opposite direction again. In the same way the valve comes at rest on the stopper that defines its "maximum-open-position" before switching over again. That way the hydraulic resistance of the valve can be controlled by determining how long the valve is fully closed and how long the valve is fully opened per time interval.
The second mode is called the "ballistic" mode: There is always a switching over from moving the valve body in one direction to moving it in opposite direction before the valve body comes at rest on the valve seat. In the same way there is a switching over again before the valve comes at rest on the stopper that defines its "maximum-open-position". That way the number of "hits" between the valve body and the valve seat and/or the stopper is drastically reduced, being positive in regard to wear and/or fatigue of the contact zones.
A mix of the first and the second operation mode is possible.
In each case one can call this valve a "pulsed" valve. This allows a very dynamic control as it is required to precisely master - as an example - frictional conditions that may vary along the guide rail within short distances, and/or to master a rope break when the elevator car is positioned only a few meters above the pit. An important advantage is that a pulsed valve is clearly more tolerant in regard to solid particles polluting the hydraulic fluid, because the pulsed valve does (different from a slide valve) not stay stationary in a position which forms a narrow gap that may be clogged by small particles carried by the hydraulic fluid.
According to another preferred embodiment, the hydraulic system comprises in addition to the pressure control line with the control valve a throttling line with a throttle control valve for noise reduced application of the hydraulic brake during or after landing of the elevator car, and/or a short-circuit line with a short-circuit valve for quick brake application in case of emergency, and/or a brake release line with a brake release valve for releasing the brake without activation of an hydraulic pump to such an extent that a new ride can start.
The aforementioned throttling line makes a soft application of the brake possible, that way avoiding the emission of audible noise when the elevator car brake applies when the elevator car has come or is coming to a standstill in a landing in order to avoid unintended car movement. That essentially improves the comfort of the ride. When the throttle control valve V3 is fully open, the throttling line still represents a hydraulic resistance that is preferably bigger than the hydraulic resistance of the control line and/or the short-circuit line when their according valves are fully open.
The provision of an additional short-circuit line with a short-circuit valve for quick brake application provides for redundancy. If the short-circuit valve is a valve that opens when not being energized, the system becomes absolutely fail-safe - when an emergency happens, the brake will apply even in case of power blackout and/or battery failure. The hydraulic resistance of the short-circuit line is preferably very small. That way the hydraulic fluid can be quickly displaced from one of the working chambers to the other working chamber, making the brake apply as fast as possible.
An additional brake release line with a brake release valve once again improves the comfort of the ride.
This brake release line interconnects the at least one actuator holding the brake actually closed upon actuation of the brake release valve with a pressure accumulator, or even at least one other brake actuator that exerts in this moment no braking action. That way a pressure compensation between the at least one active brake actuator and the pressure accumulator, or the at least one inactive brake actuator can take place. That releases the active brake actuator(s) at least to such an extent that a new ride can begin. The advantage is that it is not necessary in this phase to operate the hydraulic pump in order to at least partially release the brake. Later on, as soon as the travel speed of the elevator car is high enough to oversound or to mask the noise generated by the hydraulic pump, the hydraulic pump is activated to provide for full brake release and/or activated to charge the pressure accumulator or the at least one other brake actuator that has been involved into the silent brake release.
Preferably, the hydraulic supply unit comprises a hydraulic pump or a hydraulic pressure generator that is activated at least during performance of the inventive open or close loop control method without being itself speed, torque, or frequency, or power consumption controlled anyhow. At other times the hydraulic pump is preferably completely turned off. Here, the variation of the speed with which the pump is operated may be a consequence of the varying load conditions, there should normally be no external influencing or controlling of the speed. That decreases the expense compared to a speed-variable pump.
A preferred embodiment provides that the hydraulic cylinder is a double acting cylinder forming a first and a second working chamber. These working chambers are interconnected with one another that way that the same amount of hydraulic fluid as displaced from the first working chamber is taken up by the second working chamber when the piston moves. Such a hydraulic cylinder can be called a "double-rod" or "double stroke" cylinder. The big advantage of such a "double-rod" or "double stroke" cylinder (with equal piston-rod diameters) is that the full amount of hydraulic fluid that is displaced from one working chamber can - preferably directly - be taken up by the other working chamber. It is not necessary to vent a part of the displaced hydraulic fluid into the tank or reservoir and to feed it in again into the hydraulic system and out of the tank later.
Accordingly, only short ducts for the hydraulic fluid are required so that the stability and the response of the open or close loop control are improved. Moreover, the natural aging process of the hydraulic fluid is retarded due to the fact that a hydraulic system not always discharging a part of the hydraulic fluid into a tank gives the atmospheric oxygen, atmospheric humidity, and, maybe, particles of soil less detrimental access to the hydraulic fluid. That is important for an elevator car brake that has to be stable over long periods.
Preferably, the elevator comprises an elevator car brake with two or more hydraulic actuators, whereas at least the first working chambers or the second working chambers have a direct fluidal interconnection in the shape of a common rail. In some cases a first common rail is provided that interconnects all first working chambers and a second common rail that interconnects the second working chambers. In other cases a common rail may be divided by a valve into two parts when the valve is closed. That allows to define two, or two groups of actuators that can be operated independently from each other.
Another important option is to proceed that way that in the beginning of a departure the elevator car brake is opened by means of the pressure stored in a pressure accumulator, while the hydraulic pump starts with a delay. Preferably, the hydraulic pump is not started before the elevator car has reached at least 50 % of its regular travel speed. Another possibility is to drive the pump with a speed increasing according to the actual travel speed of the car during acceleration. That improves the ride comfort essentially: In order to avoid unintended car movement, the elevator car is secured during landing by means of applying the brake. In case that the hydraulic brake is reopened by starting the hydraulic pump before the elevator car has begun to move again, even the rather low noise of a modern hydraulic pump is clearly audible and therefore disturbs the impression of a comfortable ride. Instead the hydraulic pump will be started with a delay. Hence the hydraulic pump will not be started before the elevator car travels again with a speed that produces a driving noise sufficient for over-sounding the noise emission of the hydraulic pump.
Preferably, the brake comprises at least two of the initially defined hydraulic actuators being assigned to at least one brake pad, whereas one of these hydraulic actuators is used under regular operation as a hydraulic pressure accumulator delivering the pressure required for opening the elevator car brake in the beginning of a departure without operating the hydraulic pump. According valves required for performing such an operation are provided.
The basis for this approach is the following trick: In order to open a first brake pad belonging to a set of first brake pads applied to the guide rail for blocking against unintended car movement, at least to such an extent that the travel of the elevator car can start again, another, second brake pad of a second set of brake pads is moved in direction onto the guide rail to an extent that does not hinder the start. The movement of said second brake pad displaces that volume of hydraulic fluid that is required to open the first brake pad. Even if not required, it may be that one or both of said brake pads are dragged now along the guide rail, however, this is harmless. As soon as the elevator car has gained speed again, the hydraulic pump is started and provides now for fully retracting/lifting off the brake pads.
The aforementioned second brake lining whose hydraulic cylinder is used as a pressure accumulator, is preferably a brake pad belonging to an additional brake that is to be applied to the guide rail in case of an emergency only. In this case it is preferred to avoid that this second brake lining comes into dragging contact with the guide rail in other than emergency cases. Hence a design and/or steering should be chosen that stops moving this brake lining in direction to the guide rail before it contacts the guide rail in that way that the hydraulic cylinder assigned to this brake lining can be used as a pressure accumulator, too.
An according operation is possible, if a plurality of actuators operates the same brake pad: The actuators pressing actually onto the brake pad are released by moving the other, inactive actuators in direction onto the brake pad.
Alternatively it is possible to provide one hydraulic actuator that may be of the same type like the hydraulic actuators operating the brake pads, whereas this actuator is not assigned to a brake pad. The sole and only purpose of such an actuator may be to form a pressure accumulator that delivers the necessary amount of hydraulic fluid that is required to open the first braking pad as depicted before.
Preferably, the hydraulic elevator car brake used for performing the inventive method comprises an acceleration sensor, the signal of which is used in order to control the brake force, preferably in such a way that it is ≤ 1 g.
It is a preferred option that the elevator car brake comprises several hydraulic actuators acting all onto the same brake lining. Depending on the size of the currently needed brake force, all or individual actuators of one elevator car brake unit are activated. That way it is possible to tune the required brake force.
It is a further option that the elevator car brake comprises several hydraulic actuators acting onto different brake linings. Depending on the size of the currently needed brake force, all or individual actuators of one elevator car brake unit are activated. That way it is not only possible to tune the required brake force. A main advantage is that it is possible that way to completely save one or more brake linings for performing an emergency braking while being sure that these brake linings have not been subject of wear during regular operation of the elevator the time period before.
During standby of the elevator car the hydraulic pump is switched off while one or more valves are operated in such a way that the elevator car brake applies and develops its full brake force or the brake force necessary to prevent unintended car movement. That way the elevator car can be hold in standby position without any unintended car movement and with a minimum or no expenditure of energy.
Independent from the invention embodied by the claims discussed up to now, protection is sought for a method for open or close loop control of a hydraulic elevator car brake with a hydraulic actuator which has at least one piston rod that is pre-stressed by a main spring unit in closing direction with a force necessary for generating the required brake force (the definition given above for this applies here, too), whereas the piston rod is connected to a piston which, depending on the hydraulic pressure applied to it, completely or partly compensates the force of the main spring unit, characterized in that the resulting force with which the brake lining operated by the piston rod is pressed against the rail is open or close loop controlled by means of a speed-controlled and/or torque-controlled and/or multi-quadrant-operated motor which, as first alternative, depending on the actual needs, either drives a hydraulic pump in such a way that the hydraulic pump conveys hydraulic fluid and thus reduces the resulting force acting on the brake lining, or which acts as a generator or a braking motor braking a hydraulic pump in such a way that a - preferably close or open loop controlled - stream of the hydraulic fluid flows back via the hydraulic pump driven by the hydraulic fluid in the opposite direction of its actual conveying direction and thus increases the resulting force acting on the brake lining, and which, as second alternative, depending on the actual needs, drives a hydraulic pump in such a way that the hydraulic pump either conveys hydraulic fluid and thus reduces the resulting force acting on the brake lining, or that a leakage flow flows back via the hydraulic pump in the opposite direction of the conveying direction and thus increases the resulting force acting on the brake lining.
As another alternative concept, depending on the needs of the actual elevator operating conditions, the motor drives a hydraulic pump in such a way that the hydraulic pump either conveys oil and thus reduces the resulting force acting on the brake lining, or that a leakage flow flows back via the hydraulic pump in the opposite direction of the conveying direction and thus increases the resulting force acting on the brake lining. For generating such a leakage flow it can be sufficient, if the motor holds the hydraulic pump in standstill.
Further modes of operation, advantages and design possibilities of the invention result from the embodiments described by means of the figures.
Some general preliminary remarks on the elevators described here within the framework of the preferred embodiments are to be made which apply to all embodiments:
The elevator consists of a preferably gearless designed elevator drive 1 and an elevator car 4 which is led longitudinally - when traveling along the elevator car guide rails 2 - by means of guidance devices 3, and which shows the form of a closed cabin as a rule.
The elevator is preferably a rope elevator which is held at a number of support ropes which are not represented figuratively and which are mostly led via a traction sheave driven by the elevator drive which is also not shown.
From there the support ropes run directly or indirectly to a counterweight which can be moved at counterweight rails, which is also not represented figuratively here. They are attached to it or they bear the counterweight mounted in a block and tackle arrangement.
The elevator in accordance with the invention preferably dispenses with the so-called drive brake, or uses the latter only for reasons of redundancy. In this connection a "drive brake" is not the regenerative operation of the drive for reasons of possible energy recovery, but an additional mechanical brake which as a rule affects a brake drum or disc which is coupled with the drive shaft in order to avoid unintended car movement during landing, for example.
The elevator dispenses with a traditional overspeed governor embodied as a circulating rope which is attached to the elevator car, and thus compulsorily operated by it, and which runs via an overspeed governor which brakes the rope in the case of a certain speed being exceeded, and thus generates a mechanical force which activates the gripping device of the elevator car, and thus brings the elevator car to a standstill.
Instead, the elevator in accordance with the invention is equipped in most cases with a shaft copying device. As a rule, the latter consists of a route reference 5 which is fixedly attached next to the elevator car 4 along the traffic route, and a displacement sensor 6 which is attached to the elevator car and interacts with the route reference 5. In this case the shaft copying system cannot only determine the way, but can instead or preferably determine the related speed and/or acceleration information.
Alternatively the shaft copying system can also or additionally (redundancy) consist of a measurement installation which gathers information on route, speed, and/or acceleration via one or more wheels rolling at the rails and/or guide rails.
Again, alternatively or additionally, the shaft copying system can consist of a contact-free working range finder which permanently or close meshedly measures the current distance to a reference fixed point which is preferably located in the shaft pit and/or the shaft head and gathers the necessary rout, speed and/or acceleration information in this way. Preferably the shaft copying device measures the absolute position via at least one reference point e.g. in the shaft pit.
In the case of this first concept, the elevator in accordance with the invention is equipped with a safety brake ESB which preferably consists of at least two electrically operated elevator car brake units 7a, 7b, which are attached to the elevator car at different positions and affect the guide rails. As a rule, each of the elevator car brake units forming the safety brake is designed in such a way and controllable by the control 10 of the elevator car that the speed or force can be influenced with which its brake linings apply. The said control 10 of the elevator car can be a control exclusively assigned to the brakes that does not steer other functions like opening or closing of the car doors, for example. For steering this other functions the elevator car may be equipped with another control, embodied as a separate part and not depicted by
That way it is possible to improve the ride comfort - for example because a softer application of the brake linings after landing becomes possible, emitting no or less noise. Optionally the safety can be improved, too, because it can be considered to initiate the braking slower and therefore softer in case of an irregular ride condition. For the realization of the safety brake ESB preferably elevator car brake units are used which will be described in detail later on within the framework of this application.
In addition, the elevator in accordance with the invention is equipped with an electrically operated additional brake ESG which itself preferably consists of at least two electrically operated additional brake units 8a, 8b which are attached to the elevator car at different positions and affect the guide rails. The additional brake ESG is also controlled by the control 10 of the elevator car. For sake of completeness it is to be mentioned that this control 10 of the elevator car may optionally be a control that is exclusively assigned to, and possibly integrated into the car brakes. Then it can be called control 10 of the elevator car brake. It may be advantageous to design the additional brake in such a way that its response time is always minimal and its response intensity is always maximal - both compared to the safety brake and its preferably variable response times and response intensities. In this case brake units in the style of conventional brake mechanisms, safety catches and progressive safety gears can be used. However, contrary to the customary, these are designed in such a way that they alone do not apply the necessary brake force, but only part of it, while the rest of the maximally necessary brake force is applied by the safety brake. Thus, contrary to the standard, the worst case of the free fall is controlled by the safety brake and the additional brake together, to the effect that these necessarily have to interact.
It should be mentioned that the control of the safety brake ESB and the control of the additional brake ESG is preferably accomplished by the above-mentioned control of the elevator car, alternatively at least one of these brakes can also be controlled and/or triggered from a central elevator control.
For the realization of the additional brake ESG preferably also such brake units are used as described later within the framework of this application, i.e. brake units which can be operated cascadedly and wnicn combine the brake units necessary for the realization of the safety brake and the additional brake to a single elevator car brake unit.
Preferably, a power distribution is made between the safety brake ESB and the additional brake ESG, to the effect that one of the two brakes can apply at least 40 %, even better at least 45 % of the brake force which is necessary for the safe control of the free fall with full elevator car load, while the part of the brake force missing for 100 % is applied by the other brake. Insofar as the two brakes are not fully or essentially equal, which is preferred, the additional brake ESG is preferably the one which can apply a higher portion of the brake force.
For the realization of the invention it can be advantageous, according to the teaching of this first concept, if the safety brake ESB and the additional brake ESG are attached to different places of the elevator car. The brake units 8a, 8b of the stronger responding additional brake ESG are preferably attached in the lower half and ideally in the lower quarter of the elevator car. The elevator car brake units 7a, 7b of the softer responding safety brake ESB are preferably attached in the upper half and ideally in the upper quarter of the elevator car.
As already mentioned, a control 10 of the elevator car can be provided which travels with the elevator car 4. This control 10 is of the above-mentioned type. The control 10 of the elevator car preferably communicates with the elevator control 9 which carries out the total management of the elevator unit. Nevertheless, as a rule, the control 10 of the elevator car is designed in such a way that it can act autonomically, i.e. perform autonomically an open or close loop control.
As a rule, the control 10 of the elevator car or the elevator car brake itself (the brake unit itself) is equipped with an emergency power supply so that even in the case of power failure it can at least keep the additional brake ESG open and control it.
As a rule, the already mentioned control 10 of the elevator car is directly linked to the shaft copying system, thus constantly receives without detour via or processing by the central elevator control 9 current route, speed and/or acceleration information by means of which it can determine the current position and the current movement state of the elevator car.
Independent from the shaft copying system and the route, speed, and/or acceleration information delivered by it, the control 10 of the elevator car can additionally comprise at least one, better at least two acceleration sensors which independently generate an acceleration signal or use acceleration signals of sensors already included in the brake units. It is an option to design the brakes that way that they can be directly actuated by the acceleration signal of the aforementioned acceleration sensors.
As has already been mentioned, preferably, the control 10 of the elevator car is directly linked to the ESB safety brake 7a, 7b, and the ESG additional brake 8a, 8b, to the effect that the control 10 of the elevator car can activate the safety brake ESB (and, if necessary, the additional brake ESG) autonomously, without involvement of the central elevator control 9.
Preferably, the control 10 of the elevator car includes two independently acting circuits, one of which controls the ESB safety brake 7a, 7b, taking into consideration the shaft copying system, and the other one controls the ESG additional brake 8a, 8b, taking into consideration the information received from the at least one additional acceleration sensor.
The control 10 of the elevator car is in combination with the safety brake ESB and the additional brake ESG as well as (optionally) the central elevator control designed in such a way that at least one, better several and preferably all following conditions can be realized:
If free fall is detected, for instance due to the occurrence of an irregular high acceleration signal, and there is no power failure, preferably both, the safety brake ESB and the additional brake ESG are activated so that they brake together. Hereby the activation of the safety brake ESB is preferably carried out in such a way that it applies with maximum speed. The same applies preferably to the additional brake ESG, insofar as the latter is not constructed in such a way that it always applies with maximum speed after its activation.
Hereby the safety brake ESB and the additional brake ESG are designed in such a way that they in collaboration, altogether catch an elevator car allocated with nominal load with a deceleration of 0.2 g to 1 g, while the deceleration with an empty elevator car can rise above 1 g.
As a rule, the activation of the safety brake ESB will take place with the help of the signal delivered by the shaft copying system and with the help of at least one first circuit of the elevator car brake. The activation of the additional brake ESG can take place via the above-mentioned at least one additional acceleration sensor or with the help of at least one independent further circuit of the control for the elevator car brake.
If free fall is detected, e.g. due to the occurrence of an irregular high acceleration signal while power fails at the same time, the safety brake ESB responds due to the power failure unless it has been activated before due to over-acceleration on the basis of the signal delivered by the shaft copying system or the at least one acceleration sensor. As a rule, an inevitable application (closing) of the safety brake ESB in the case of power failure takes place, because the forces keeping it in open position collapse as a result of the power failure. The additional brake ESG is different. It is connected to the emergency power supply which actually keeps it open so that the additional brake ESG is still not activated per se due to the power failure, but preferably because of the fact that the at least one additional acceleration sensor delivers an acceleration signal which shows the free fall, or the control for the elevator car brake detects insufficient deceleration of the car by the ESB. Should the emergency power supply fail, too, then the additional brake ESG will apply, too, due to de-energizing.
Here again both brakes are designed in such a way that they are in collaboration able to catch an elevator car allocated with nominal load with a deceleration of 0.2 g to 1 g, while the deceleration with an empty elevator car can rise above 1 g.
In the case of an emergency stop without power failure, for instance because one of the elevator shaft doors was opened during the ride, the safety brake ESB is activated by the safety circuit, while the additional brake remains inactive. The safety brake preferably applies with maximum speed.
Hereby the safety brake is preferably designed in such a way that it causes a deceleration < 1 g with this kind of activation, as a rule because its maximum available deceleration is innately under 1 g.
Analogously the same applies to the interference of emergency stop and power failure, with the difference that the safety brake is activated by the power failure, unless the safety circuit has responded before.
If, e.g. due to the occurrence of a super-elevated speed signal (maybe in the case of a simultaneously uncritical acceleration signal), overspeed is detected in roped condition, and there is no power failure, the safety brake ESB will be activated, while the additional brake ESG is kept open. The safety brake preferably applies with maximum speed. Hereby the safety brake is designed in such a way that it applies a deceleration < 1 g. As a rule, the activation of the safety brake will take place with the help of the signal delivered by the shaft copying system.
Analogously the same applies to the interference of overspeed in roped condition and power failure, with the difference that the safety brake is activated by the power failure, unless the safety circuit has responded before.
The safety brake ESB is activated, the additional brake ESG is kept open.
The activation of the safety brake ESB takes place deceleratedly, to the effect that the speed, with which the safety brake applies until it reaches is maximum brake and/or holding force, is reduced in order not to create disturbing noises.
If there is a power failure in the stop, the safety brake ESB closes completely due to the power failure (unless it has already done so) and remains closed for the time of the power failure. However, the additional brake ESG remains open.
The safety brake ESB will always be closed in such a way that it keeps the elevator car in a certain position, if the elevator car has stopped in the correct position of the stop, independent from the current weight of the elevator car which changes due to loading and unloading at this stop.
It can be convenient to not abruptly, but deceleratedly open the safety brake ESB after the loading and unloading process in such a way that the elevator car does not noticeably sag by some mm under the influence of a now possibly heavier load before the actual ride starts. The control 10 of the elevator car is designed accordingly.
If the elevator car is in standby, i.e. in its waiting position for the next ride, the safety brake ESB will remain closed, in order to reduce the energy consumption. However, the additional brake ESG is kept open and remains on standstill, in order to be able to intervene immediately, if the free fall occurs for any reason.
The safety brake ESB and the control assigned to it are preferably designed that way that the safety brake will close as soon as it has been detected that the elevator car approaches the lowermost or uppermost landing with a speed that is too high for a regular stop.
The safety brake ESB and the control assigned to it are preferably designed that way that an automatic emergency rescue will take place when pressing a button: Upon according activation, the safety brake ESB is partially opened so that the elevator car can move - even without motor power driven by the predominant weight force of the car or the counterweight - with a restricted speed into the adjacent landing. During this operation the motor carrying the traction sheave will be preferably short-circuited in order to generate a braking torque.
The safety brake ESB and the control assigned to it are preferably designed that way that they will automatically provide for a protected space in the pit or the shaft head as soon as it has been detected that a person has entered the pit or the shaft head.
In the case of this embodiment, the elevator in accordance with the invention is equipped with a safety brake ISB which consists of at least one, preferably two electrically operated elevator car brake units 7'a, 7'b which are attached to the elevator car at different positions and affect the guide rails.
The safety brake ISB is designed and controllable in such a way that the speed of its application can be influenced, and that its brake force is also influenceable, preferably by means of a close loop control.
Unlike the first embodiment of the invention, no additional brake is provided here. The safety brake ISB is designed in such a way that it is able to master all possible regular and irregular operating conditions alone. For this purpose each of the elevator car brake units 7'a, 7'b, is provided with at least one actuator - better several actuators - which preferably consists of several piston/cylinder units, not least for the purpose of reaching partial redundancy.
Furthermore, as a rule, an emergency power supply is provided which feeds the safety brake ISB and mostly the shaft copying system as well.
The special thing about this system is that it is designed and construed in such a way that the brake forces applied by the elevator car brake units can be open loop controlled and/or preferably close loop controlled.
An own acceleration sensor 10a, 10b, is preferably allocated to each elevator car brake unit 7'a, 7'b, the signal of which is the basis for the open or preferably close loop control of the brake force of the corresponding elevator car brake unit 7'a, 7'b. The corresponding acceleration sensor 10a, 10b, is preferably integrated into and/or attached to the corresponding elevator car brake unit. Ideally, the corresponding signal processing and the generation of the control and/or regulation signal for the elevator car brake unit 7'a and/or 7'b also take place directly in and/or at the corresponding elevator car brake unit. For this purpose, it is preferably the case that each elevator car brake unit is designed in such a way that it works hydraulically autonomically, i.e. each elevator car brake unit has an own hydraulic pump 19, an own equalizing tank or pressure equalizing vessel 20, and the complete set of hydraulic valves, lines and other hydraulic auxiliary installations which are necessary for its operation.
The several elevator car brake units are connected to each other - preferably directly, however, at least via the control of the elevator car brake. Hence their corresponding signals and/or activities can be compared to each other in order to detect possible faults at an early stage. Ideally there is even a double connection: Between the several elevator car brake units there is both a direct information exchange via the signal line 10c and an indirect information exchange via the control of the elevator car brake.
If a fault is detected, the elevator car will be stopped after reaching the next stop.
The system is designed in such a way that at least one, better several and preferably all of the following conditions can be realized.
If free fall is detected, e.g. due to the occurrence of a correspondingly high acceleration signal, the brake applies with maximum speed and is preferably close loop controlled in such a way that a deceleration < 1 g is set, ideally in the form of a medium deceleration between 0.5 g and 0.7 g. As has been mentioned before, an acceleration sensor 10a, 10b, is allocated to each elevator car brake unit, the signal of which is used for adjusting. Since there is a close loop control, it is not important with which load the elevator car is assigned, the deceleration as requested is adjusted in any case.
This applies, too, also in case of a power failure as long as the emergency power supply goes properly into effect.
If free fall is detected, e.g. due to the occurrence of a correspondingly high acceleration signal, and if also a total power failure occurs (blackout line current and failure of emergency power supply), the safety brake ISB will respond due to the power failure, unless it has been activated before due to over-acceleration on the basis of the signal delivered by the shaft copying system. The latter will take place, as a rule, due to the fact that the forces keeping it in opened position collapse as a result of the total power failure.
In the case of an emergency stop, for instance because one of the elevator shaft doors has opened during the ride, the safety brake ISB is activated by the safety circuit. The safety brake preferably applies with maximum speed. The safety brake is then preferably close loop controlled in such a way that it causes a deceleration < 1 g, ideally in the form of a medium deceleration between 0.5 g and 0.7 g.
Analogously, the same applies to the interference of emergency stop and total power failure (blackout line current and failure of emergency power supply), with the difference that the safety brake is activated by the power failure, unless the safety circuit has responded before. In this case, the safety brake will produce the maximum deceleration.
If, e.g. due to the occurrence of a super-elevated speed signal (maybe in the case of a simultaneously uncritical acceleration signal), overspeed is detected in roped condition, the safety brake will be activated. The safety brake preferably applies with maximum speed and is then preferably controlled in such a way that a deceleration < 1 g is set, ideally in the form of a medium deceleration between 0.5 g and 0.7 g.
The safety brake ISB is activated.
The activation of the safety brake preferably takes place by means of a throttled valve or by open or close loop control, to the effect that the speed with which the safety brake applies is influenced and/or reduced by the throttle or the open or close loop control in order not to create disturbing noises. This can mean that the safety brake closes with full force, however, it takes some time until the full force is available.
If there is a total power failure in the stop (blackout line current and failure of emergency power supply), the safety brake ISB closes completely due to the power failure (unless it has already done so) and remains closed for the time of the power failure.
The safety brake will always be closed in such a way that it keeps the elevator car in a certain position, if the elevator car has stopped in the correct position of the stop, independent from the current weight of the elevator car, which changes due to loading and unloading at this stop.
The elevator car brake ISB and the control assigned to it are preferably designed that way that the safety brake will close as soon as it has been detected that the elevator car approaches the lowermost or uppermost landing with a speed that is too high for a regular stop.
The elevator car brake ISB and the control assigned to it are preferably designed that way that an automatic emergency rescue will take place when pressing a button: Upon according activation, the elevator car brake ISB is partially opened so that the elevator car can move - even without motor power driven by the predominant weight force of the car or the counterweight - with a restricted speed into the adjacent landing. During this operation the motor carrying the traction sheave will be preferably short-circuited in order generate a braking torque.
The elevator car brake ISB and the control assigned to it are preferably designed that way that they will automatically provide for a protected space in the pit or the shaft head as soon as it has been detected that a person has entered the pit or the shaft head.
In advance a general information in regard to the inventive brake units has to be given.
Theoretically, the provision of only one single of the inventive car brake units is sufficient. Preferably, an elevator car is equipped with at least two of the inventive car brake units that interact with different rails.
In advance some general information in regard to the valves has to be given.
Valves hereinafter referenced as V1 are the so-called short-circuit valves that block or open a so called short-circuit line which directly interconnects a first working chamber 14 and a second working chamber 15 of a hydraulic actuator. This valve will be opened in case if an emergency braking is necessary for putting an end to irregular running conditions. This valve V1 is for making the brake fail-safe, because it guarantees quick brake application, even if other valves do not work properly.
Unless otherwise defined, valves hereinafter referenced as V2 are the so-called control valves that open or close loop control the instantaneous braking power during braking. Preferably, the valves of the type V2 are realized as so-called valves for exclusive on-off-service, as explained in greater detail before.
Valves hereinafter referenced as V3 are so-called throttle control valves for opening or closing a throttling line for noise reduced application of the hydraulic brake during or after landing of the elevator car. The throttle control valves may themselves produce a throttling effect, and/or the throttling line may itself produce the required throttling effect, as explained in greater detail before.
Valves hereinafter referenced as V23 are combined valves that realize both, the function of the aforementioned valve V2 and the function of the aforementioned valve V3.
Valves hereinafter referenced as V4 are brake release valves opening or closing a brake release line for releasing the brake without activation of an hydraulic pump at least partially to such an extent that a new ride can start.
Valves hereinafter referenced as V34 are combined valves that realize both, the function of the aforementioned valve V3 and the function of the aforementioned valve V4.
Unless something else is explicitly provided, a valve is a proportional valve and no switching valve.
Unless something else is explicitly notified, all valves are valves that are opened, i.e. that allow passage of hydraulic fluid when being de-energized.
In the Figures this is indicated by the spring element that presses onto the moveable valve body. The rule is that as soon as - for whatever reasons - no power supply for the valves is available anymore, the valves open and apply maximum brake force that way.
The car brake unit comprises a first group of hydraulic actuators 11.1.1 up to 11.1.x and a second group of hydraulic actuators 11.2.1 up to 11.2.x. Each of these actuators comprises a cylinder 12 with a piston 13 dividing the cylinder into a first working chamber 14 and a second working chamber 15. Moreover, each of these actuators comprises a piston rod 31 acting onto a brake lining 16 and a spring element 17 that is part of the main spring unit responsible for producing the required brake force even in case of breakdown of hydraulic pressure.
In regard to the brake linings 16 the following has to be notified with general effect to all embodiments: Each of the two or several actuators can affect (press upon) one single brake lining or a common brake lining.
As one can see, all first working chambers 14 of the actuators 11.1.1 to 11.1.x are in direct hydraulic interconnection, they are connected in series along one hydraulic loop 114. Moreover, all second working chambers 15 of the actuators 11.1.1 to 11.1.x are in direct hydraulic interconnection, in series along a hydraulic loop 115 that forms a "common rail". If the valve V4 is open, the first working chambers 14 of all existing hydraulic actuators are connected in series as all the second working chambers 15 are.
The hydraulic pump and the control valve V23 are positioned upstream in front of the working chambers 14. The expression "upstream" is used here and everywhere in this application related to the pumping direction of the hydraulic pump 19 under single-quadrant operation. That means that the pressure side D of the pump 19 is upstream of the first working chambers 14, while the suction side S of the pump 19 is downstream of the second working chambers 15.
The short-circuit valve V1 is positioned downstream behind the working chambers 14. Only the valve V4 is positioned between two functionally identical working chambers, in this particular case between two first working chambers 14.
Regular conditions provided, the hydraulic pump runs during braking down the elevator car to standstill continuously without speed-, power-, torque- or frequency-control under single-quadrant operation. The pressure side D of the hydraulic pump 19 feeds the first working chambers 14, while the suction side S of the hydraulic pump 19 is connected to the second working chambers 15 so that it can draw-off hydraulic fluid from there. A check-valve CV is provided in order to make sure that there is no backflow of hydraulic fluid via the pump 19 when the pump is shut off and when the valve V23 is closed.
A control line 39 is provided that directly interconnects the hydraulic loop 115 of the second working chambers 15 with the hydraulic loop 114 of the first working chambers 14. The control line 39 is operated by the control valve V23.
When the hydraulic pump 19 is conveying hydraulic fluid, while the control valve V23 is continuously fully closed, the brake will be released quickly, because the hydraulic pump draws off hydraulic fluid from the second working chambers 15, pumping it into the first working chambers 14 - this happens with the hydraulic actuators 11.1.1 to 11.1.x, if valve V4 is closed, and with all hydraulic actuators 11.1.1 to 11.2.x, if valve V4 is opened.
In case the control valve V23 is continuously fully opened, the control line 39 short-circuits the hydraulic loop 114 of the first working chambers 14 with the hydraulic loop 115 of the second working chambers 15 so that the brake will apply quickly, because the hydraulic fluid will be displaced from the first working chambers 14 to the second working chambers 15. The enduring pumping action of the hydraulic pump 19 will in this case remain without effect, because the hydraulic pump is short-circuited, too.
Starting from this insight, it becomes clear that the amount of hydraulic fluid that flows from the first working chambers 14 into the second working chambers 15 can be controlled by tuning the instantaneous, hydraulic resistance of the control valve V23 accordingly. As explained above, the "opening degree" of valve V23 can be remote controlled by the controller assigned to the valve V23, for example by tuning the frequency with which the valve body moves back and forth.
As already described above, the valve V23 is able to realize a throttling effect, that way providing for a slow brake application during or after landing. That way an unintended car movement can be avoided without generating noise.
As one can see, additionally a short-circuit line 40 is provided that directly interconnects the hydraulic loop 114 of the first working chambers 14 with the hydraulic loop 115 of the second working chambers 15. The short-circuit line 40 is operated by the short-circuit valve V1. In case of emergency braking, the valve V1 is opened as well as the valve V23 in order to produce quickest possible braking action of the hydraulic actuators 11.2.1 to 11.2.x. Even if all other valves should jam, the valve V1 makes the actuators 11.2.1 to 11.2.x braking. Normally all valves are opened for emergency braking so that the hydraulic fluid can be displaced as fast as possible from the first working chambers 14 into the second working chambers 15.
The valve V4 has several functions.
At first the valve V4 makes it possible to actuate actuators 11.1.1 to 11.1.x and 11.2.1 to 11.2.x separately from each other. That way it is possible to realize the above mentioned concept "ESB and separated ESG" with one of these brake units. As long as the valve V4 is kept closed, only the ESB-function is realized by means of the actuators 11.1.1 to 11.1.x. Upon additional opening of the valve V4 and/or the valve V1, the actuators 11.2.1 to 11.2.x perform the ESG-function.
Moreover, the valve V4 makes it possible to release the actuators 11.1.1 to 11.1.x when the car is on train to start a new ride, while the hydraulic pump 19 is still shut down in order to avoid audible noise emission, while the elevator car stands still at a landing.
For that purpose the valve V4 is opened so that via the loops 114 and 115 a pressure compensation between the first working chambers and the second working chambers of the actuators 11.1.1 to 11.1.x and 11.2.1 to 11.2.x will take place. In consequence, the actuators 11.2.1 to 11.2.x close partially, releasing the actuators 11.1.1 to 11.1.x that way partially. The braking forces are now at least to such an extent lowered that the elevator car can start a new ride - without starting the hydraulic pump 19 during standstill of the elevator car in the landing.
The hydraulic pump 19 will be started after the new ride has begun, preferably not before the riding-noise of the elevator car is at least as loud as the noise emitted by the hydraulic pump so that the noise of the hydraulic pump does not impact the comfort of the ride.
Preferably, the valve V4 provides for a throttled hydraulic interconnection of the actuators 11.1.1 to 11.1.x with the actuators 11.2.1 to 11.2.x. That way the pressure compensation between said groups of actuators will not take place suddenly and therefore audibly upon opening of the valve V4, but retarded without emitting an acoustic pulse.
All things explained before apply to the embodiment according to
The only difference of the embodiment according to
That allows to operate the hydraulic pump under two-quadrant operation, as explained in greater detail below when discussing
The valve V3 serves for slow application of the brake at landing without noise emission, as explained above.
This embodiment uses only one group of hydraulic actuators 11.1.1 up to 11.1.x and an additional pressure accumulator 111. Preferably, the pressure accumulator 111 is constructed identical to the actuators 11.1.1 et al., except for the fact that the piston rod 31 of the pressure accumulator is not assigned to a brake pad. It has the advantage that even if the piston rod 31 of the pressure accumulator moves when the first working chamber is emptied in order to release the actuators 11.1.1 up to 11.1.x, this does not lead to a dragging contact between a brake pad assigned to its piston rod and the braking rail.
In regard to one working chamber - preferably the second working chamber 15 - all the actuators 11.1.1 to 11.1.x and the pressure accumulator are permanently in direct hydraulic interconnection. That means that their second working chambers, including the second working chamber of the actuator, are connected in series along one hydraulic loop 115 that forms a permanent "common rail" for these hydraulic working chambers.
In regard to another working chamber - preferably the first working chamber 14 - all the actuators 11.1.1 to 11.1.x are in direct hydraulic interconnection. That means that the first working chambers 14 are connected in series along one hydraulic loop 114. The pressure accumulator 111 with its first working chamber is connected to the hydraulic loop 114, too, if the valve V4 is opened. Otherwise the pressure accumulator 111 is cut off.
A hydraulic pump 19 is provided that directly connects the upstream end of the hydraulic loop 114 (pressure side of the pump) with the downstream end of the hydraulic loop 115 (suction side of the pump). The pump is subject of single-quadrant operation, as explained above. Moreover, a pressure equalizing vessel 20 can be provided.
Due to this design, all actuators 11.1.1 to 11.1.x can only be activated synchronously. That means that one single elevator car brake of this type cannot be used in order to realize an ESB as well as an ESG, as explained above. Instead, this type of elevator car brake is provided for the ISB operation as explained above.
Different to what is disclosed by
That makes it possible to divide the individual functions of the valves completely from each other. Consequently it is possible to design the valves V2, V3, and V4 completely independent from one another.
Another advantage of this hydraulic design is the fact that it is not necessary to energize any valve during stay of the elevator car in front of a floor. Nevertheless, the full braking power is available.
In particular it is possible to apply the brake without noise emission in front of a landing by means of the throttled valve V3.
It is possible to release the brake without operating the hydraulic pump when the elevator car is going to start another ride. For this purpose the valve V4 will be opened. That way a part of the hydraulic fluid accumulated in the first working chamber 14 of the pressure accumulator 111 will be pressed into the first working chambers of the actuators 11.1.1 to 11.1.x so that these actuators are released at least to such an extent that the new ride can begin.
The open or close loop control of the braking power instantaneously applied is possible by means of the valve V2 designed for exclusive on-off-service, as explained above.
The hydraulic car brake unit comprises, as explained before in regard to
Once again, in regard to one hydraulic working chamber - preferably the second hydraulic working chamber 15 - all the actuators 11.1.1 to 11.2.x are in direct hydraulic interconnection. That means that all working chambers 15 are permanently connected in series along one hydraulic loop 115 that forms a common rail.
In regard to another working chamber - preferably the first working chamber 14 - the actuators are divided into two groups by means of the valve V4: As long as this valve V4 is closed, there is one group of actuators 11.1.1 to 11.1.x having such working chambers (chambers 14, for example) that are permanently in direct hydraulic interconnection, and another group of actuators 11.2.1 to 11.2.x where such working chambers are permanently in direct hydraulic interconnection, too.
A hydraulic pump 19 is provided that directly connects the upstream end of the hydraulic loop 114 (pressure side of the pump) with the downstream end of the hydraulic loop 115 (suction side of the pump). The pump is subject of single-quadrant operation, as explained above. Moreover, a pressure equalizing vessel 20 can be provided.
There is another loop in the shape of the throttled line 41 connecting the upstream end of the hydraulic loop 114 with the downstream end of the hydraulic loop 115. This throttled line 41 is opened or shut off by means of the valve V3. Opening of the valve V3 allows a soft applying of the brake pad(s) operated by the first group of actuators 1.1.1 to 11.1.x, without audible noise emission or with reduced noise emission. For that reason the valve V3 exerts a throttling effect or controls a loop with a throttling effect.
The valves V2 and V1, that are themselves arranged in parallel, are situated in a hydraulic loop that directly interconnects the first working chambers 14 of the second group of actuators 11.2.1 to 11.2.x via the downstream end of the hydraulic loop 114 with the upstream end of the hydraulic loop 115.
In order to prevent unintended car movement during landing, only one group of actuators is activated, here it is the group 11.1.1 to 11.1.x. This group of actuators is activated so that braking action is produced by opening the valve V3 controlling the throttling line 41. Via this throttling line 41 hydraulic fluid can be displaced from the first working chambers 14 of the actuators 11.1.1 to 11.1.x into their second working chambers 15.
In order to release the brake without operating the hydraulic pump when the elevator car is going to start another ride, the valve V4 will be opened. That way a part of the hydraulic fluid accumulated in the first working chambers 14 of the second group of actuators 11.2.1 to 11.2.x will be pressed into the first working chambers 14 of the first group of actuators 11.1.1 to 11.1.x so that these actuators are released at least to such an extent that the new ride can begin.
For performing an open or close loop controlled overspeed braking of the elevator car, the valve V2 open or close loop controls the braking power generated by the actuators 11.1.1 to 11.2.x. The hydraulic pump conveys hydraulic fluid into the first working chambers 14 of the actuators 11.1.1 to 11.1.x, and via the loops 118, 119, and the check valve CV2 in direction to the first working chambers 14 of the actuators 11.2.1 to 11.2.x, while hydraulic fluid is drawn off by the pump from all the second working chambers 15 via the loop 115 (common rail). The lower the actual hydraulic resistance of the control valve V2, the lower is the actual pressure in the first working chambers - the higher the actual braking force will be.
Due to its specific layout, the performance of an ESB/ESG operation as explained above is not possible to a practical relevant extent.
The check valve CV2 allows charging of the group of actuators 11.2.1 to 11.2.x, which served before for opening the brake without operating the hydraulic pump 19: If the pump feeds pressurized hydraulic fluid into the upstream end of the hydraulic loop 114, this fluid can reach the working chambers 14 of the actuators 11.2.1 to 11.2.x via the check valve CV2.
The check valve CV1 prevents during standstill of the hydraulic pump a detrimental leakage from flowing via the hydraulic pump from the upstream end of the loop 114 to the downstream end of the loop 115.
That way is becomes visible that the hydraulic flow through the valve V4 is bidirectional. Next, it becomes visible that the hydraulic flow through the valve V3 (when opened) is directed from the hydraulic loop 114 to the hydraulic loop 115.
The only difference between the aforementioned
The only difference is that the valves V3 and V4 have been merged now. These two valves are replaced by a combination valve V34. This replacement is possible without problems, because the valves V4 and V3 used before must always be operated in adverse direction, that means if the valve V3 has been closed, the valve V4 has been opened and vice versa.
In order to explain this, one has to give thought to what happens when the elevator car has come to standstill at the landing. At this moment, the valve V34 is switched that way that it performs the hydraulic function that was performed before by valve V3.
In order to perform the function of the previous valve V3, the valve V34 is switched that way that it directly interconnects, via a throttled passage, the hydraulic loop 114 downstream behind the actuator 11.1.x with the hydraulic loop 115 that forms the aforementioned "common rail" for the second working chambers 15, as directly shown by
An advantage of this hydraulic layout by means of the combination valve V34 is that one separate valve can be emitted, that reduces the costs.
A disadvantage is that to some extent "a pressure loss" will take place for a little moment when the valve V34 is switching over between its both positions, because during the switching over a hydraulic short-circuit occurs for a very short moment. This disadvantage could be compensated by designing the valve V34 as a slider valve. However, slider valves are sensitive in regard to dirt, and show normally a certain internal leakage that is disturbing here, too.
In this Figure only one actuator 11.1.1 is shown. However, this embodiment is not restricted to the use of one actuator. Instead, a set of actuators 11.1.1 up to 11.1.x can be used. The only thing that has to be done is to interconnect all working chambers 14 and all working chambers 15 of these actuators by means of loops 114 and 115 that are embodied as common rails.
In this embodiment downstream below the working chamber 14 the valves V1, V2 and V3 are provided. These valves are arranged in a hydraulic parallel manner. Parallel loops comprising these valves lead into a common loop 116 that goes directly to the suction side of the hydraulic pump 19.
Upstream in the hydraulic loop 114 going to the first working chamber 14 of the actuator, the valve V4 is provided. The input side of the valve V4 is interconnected with the pressure side of the hydraulic pump 19.
The special thing here is the pressure accumulator 111 that is directly interconnected with the suction side of the hydraulic pump 19 as well as with the pressure side of the hydraulic pump 19.
Another very specific design used here is the interconnection loop 117 that provides for a direct passage from the loop 116 to the second working chamber 15 of the hydraulic actuator.
The valve V2 is used for open or close loop control of the braking force in case of an emergency braking. In case of an emergency braking, the valve V4 is energized that way that it fully opens the hydraulic loop comprising this valve V4. In case of emergency braking, the hydraulic pump is constantly operated as described in greater detail above. Having that in mind, it is clear that the actual hydraulic resistance of the control valve V2 (depending on the switching operation actually performed) determines how much of the hydraulic fluid pressed by the pressure side of the hydraulic pump 19 into the first working chamber 14 (that is interconnected via the valve V2 and the hydraulic loop 116 directly with the suction side of the hydraulic pump 19) flows back to the suction side of the hydraulic pump.
It is clear that a fully closed valve V2 results in a maximum speed of releasing the brake, because all the pressurized hydraulic fluid pressed by the hydraulic pump 19 into the first working chamber 14 moves the piston of the hydraulic actuator in direction to the second working chamber 15.
On the other hand it is clear that a fully opened valve V2 produces via the first working chamber 14 a direct short-circuiting between the pressure side of the hydraulic pump 19 and its suctions side. It allows a displacement of hydraulic fluid out of the first working chamber 14 via the hydraulic loops 116 and 117 into the second working chamber 15, that way making the brake applying.
The valve V3 commands a throttle passage or is throttled itself. As explained above, the valve V3 serves for silent application of the brake during landing in order to avoid unintended car movement.
An interesting point here is the valve V4. If, during landing, the hydraulic pump is shut down, the release of the brake for starting a new ride again is accomplished by means of the pressure accumulator 111 and the valve V4. The valve V4 opens. That way the pressure accumulator displaces via the throttle 21 hydraulic fluid out of its first working chamber 14 through the valve V4 into the first working chamber 14 of the hydraulic actuator 11.1.1. The increasing pressure in the first working chamber 14 leads to a displacement of hydraulic fluid out of the second working chamber 15 of the hydraulic actuator 11.1.1. That way the brake is released to such an extent, at least, that the new ride can begin.
As soon as the elevator car has sufficient speed to oversound the noise of the hydraulic pump 19, this hydraulic pump 19 is energized again. It may provide at first for full release of the brake. Hereinafter the valve V4 may be closed. Nevertheless, the hydraulic pump 19 is still able to recharge the accumulator 111 again, because this accumulator is, as already mentioned, directly interconnected with the pressure side as well as with the suction side of the hydraulic pump 19.
The only difference between this embodiment according to
The valve V5 is used together with the valve V2 for open or close loop control of the braking force in case of an emergency braking. In case of an emergency braking, the valve V5 is energized that way that the actual hydraulic resistance of the control valve V5 determines how much of the hydraulic fluid pressed by the pressure side (first working chamber 14 of the pressure accumulator 111 and / or pressure side of the hydraulic pump 19) flows into the first working chamber 14 of the hydraulic actuator and thereby releases the brake, because all the pressurized hydraulic fluid pressed by the hydraulic pressure side of the hydraulic accumulator 111 (resp. pump) into the first working chamber 14 moves the piston of the hydraulic actuator in direction to the second working chamber 15.
Due to the fact that all actuators used for this embodiment are interconnected by loops 114 und 115 that are embodied at common rails, this embodiment cannot be used for realizing an ESB/ESG in the above mentioned sense.
For the same reason, a cascading operation first actuating one set of actuators, and next actuating another set of additional actuators is not possible.
An advantage of this embodiment is that it is not necessary to energize valves during standby of the elevator car in a landing.
Another advantage is that the hydraulic pressure accumulator 111 can be charged completely independent from the working of the actuators being responsible for braking.
Finally, important functions are completely independent so that important components like the valves V2 and V3 can be designed completely independent from each other.
These advantages apply to what is shown by
The solutions shown by
Once again, the hydraulic car brake unit comprises a first group of hydraulic actuators 11.1.1 up to 11.1.x. and a second group of hydraulic actuators 11.2.x while x can be "1" or a value between "1" and "n".
As explained above, one chamber of these hydraulic actuators, preferably the second working chamber 15, is in direct hydraulic interconnection by means of a hydraulic loop 115 that forms a common rail.
In regard to the other working chamber - preferably the first working chamber 14 - only a first group of the hydraulic actuators 11.1.1 to 11.1.x is in direct hydraulic interconnection, while another one or group of hydraulic actuators 11.2.x is not in permanent direct hydraulic interconnection in regard to the working chamber 14.
This embodiment is characterized by the fact that all its valves are arranged together with the hydraulic pump arranged upstream of the first working chambers.
Once again, the pressure side D of the hydraulic pump 19 is connected to the loop 114 upstream in regard to the first working chamber of the first group of actuators 11.1.1 to 11.1.x. On the other hand, the suction side of the hydraulic pump 19 is directly interconnected to the hydraulic loop 115 forming the common rail for all actuators 11.1.1 to 11.1.x and 11.2.x. That way the valve V2 allows an open or close loop controlled application of brake force by the first group of actuators 11.1.1 to 11.1.x. If the valve V2 is completely closed, then the hydraulic pump 19 pressurizes with full power the first working chambers 14 of the said first group of hydraulic actuators. At the same time there is a maximum of suction by the hydraulic pump 19 via the loop 115 out of the second working chambers 15. That means that the hydraulic actuators are released with maximum speed.
If, on the other hand, the valve V2 is fully opened, then the hydraulic pump 19 is completely short-circuited so that it cannot influence the first group of hydraulic actuators 11.1.1 to 11.1.x. On the contrary, the first working chambers 14 of the said first group of hydraulic actuators, and the second working chambers 15 of the said first group of hydraulic actuators, and the first working chambers 14 of the second group of hydraulic actuators, and the second working chambers 15 of the said second group of hydraulic actuators (via the check valve) are short-circuited, too, via the fully opened valve V2. That means that maximum of braking force is applied. If the status of the valve V2 is somewhere between fully closed and fully opened, it is clear that an accordingly low or high braking force will be applied.
Also here the valve V3 serves for silently closing the brake during landing in order to realize protection against unintended movement. The valve V3 interconnects, as described already before, via a throttled path the first working chambers 14 with the second working chambers 15 of the second one or group of hydraulic actuators 11.2.x, making this or these actuators applying the brake that way.
Also the valve V4 has the same function as already explained before. The valve V4 allows interconnecting the first working chambers 14 of the first group of actuators with the first working chambers 14 of the second group of actuators, making the actuators of the second group releasing that way. In the explanations before it is clear that also this embodiment cannot be used in order to realize the ESB/ESG function. Also the cascading application of different parts of the brake is not possible. In order to keep the elevator car in safe stand while in front of a landing, two valves have to be energized.
Also here it is possible to charge that part of the brake that is used as a pressure accumulator independently from the rest of the brake.
The pressure source is realized here in the shape of a hydraulic pressure accumulator 111. The valve V2 open or close loop controls with its hydraulic resistance whether and how much hydraulic fluid will be pressed by the pressure accumulator into the first working chamber 14 of the brake actuator 11. At the same time the hydraulic pressure accumulator is able to take up hydraulic fluid displaced out of the second working chamber 15 and / or hydraulic fluid short circuited by the control valve V2.
The pressure accumulator is preferably a "double stroke", "double rod" cylinder with the piston therein forming a first accumulator chamber and a second accumulator chamber, whereas the cylinder is designed that way that the equal amount of hydraulic fluid displaced from the first accumulator chamber is taken up by the second accumulator chamber when the piston, preferably driven by a spring, moves.
The hydraulic pump 19 is only operated when recharging of the pressure accumulator 111 is required.
Typically, the brake does not consist of a single, but of several hydraulic actuators which are again constructed similarly, preferably two or more pieces.
Accordingly the right area of
Each hydraulic actuator interacts with two brake linings 16 which affect a rail and/or an elevator car guide rail 2.
As long as there is sufficient hydraulic pressure in the corresponding first working chamber 14, the hydraulic actuator keeps its piston and/or the connected piston rod against the tension of its corresponding spring element 17 in ventilated position, where no compressive force is applied to the allocated brake lining 16. The spring elements 17 commonly form the so-called main spring element.
A hydraulic pump 19 is preferably driven by an electric motor 18 to ensure the supply with hydraulic pressure. Typically, but not necessarily a pressure equalizing vessel 20 is provided, which balances the bulk volume and the thermal expansion of the hydraulic fluid and possible micro-leakages.
With one side, which is the pressure side D during normal operation ("Opened brake/reduced brake action"), the hydraulic pump 19 is connected to the first working chambers 14 of the hydraulic actuators, and with the other side, which is the suction side S during normal operation, it is connected to the second working chambers 15 of the hydraulic actuators.
It is not irrelevant which type of pump is used for performing the inventive concept. For all proposed solutions a vane pump is the matter of preferred choice. For multi-quadrant operation sometimes the use of a piston pump is most preferred as hydraulic pump 19, preferably a pump/motor with a multiplicity of cylinders. This is because a piston pump is, when coupled to an appropriate electric motor, in particular suited for realizing a dual-quadrant-operation ("Zweiquadrantenbetrieb"). A dual-quadrant-operation is understood here as a mode, wherein the pump is one time operated as a pump that presses hydraulic fluid into the working chamber, and wherein the pump is another time operated as a hydraulic motor which is driven by the hydraulic fluid that leaves the aforementioned working chamber, whereas the hydraulic motor is charged by the electric motor with a braking torque determining the speed of the hydraulic fluid flowing out of the working chamber.
Like all the other embodiments, this embodiment is preferably characterized by the fact that it is operated as a closed system. That means that the hydraulic pump does not pump hydraulic fluid from a storage tank into the working chamber of a hydraulic cylinder, which will be discharged, when the time has come, back into the storage tank. Instead, the hydraulic pump circulates the hydraulic fluid from a working chamber 14 located at a first side of the respective hydraulic piston to a working chamber 15 that is located on the opposite side of the hydraulic piston. That enables a particularly quick and sensitively responding open or close loop control of the speed inherent to the hydraulic fluid that leaves the working chamber that is provided for holding open the brake, or that flows into aforementioned working chamber. This is because the closed system allows the two-quadrant-operation without time lag (that may otherwise be caused by the necessity to re-intake again the hydraulic fluid from the tank, where it is without pressure).
An externally controllable valve V2 (can be an ordinary slider valve here) is provided. If the latter is closed, it separates the working chambers 14 from the branch of the hydraulic system where the hydraulic pump 19 and the second work chambers 15 are located. This valve facilitates to keep the brake open almost without energy expenditure - if the valve V2 is closed, the first working chambers which are under pressure and ensure the overcoming of the force acting from the springs 17 in the direction of closing the brake will be separated from the remaining hydraulic circuit, and the pressure inside will be "locked" so that only the little power for keeping the valve closed has to be applied.
Additionally, a second externally controllable hydraulic valve V1 is provided, which hydraulically short-circuits the first work chambers 14 and the second work chambers 15 of the hydraulic actuators in its opened condition, i.e. which ensures a hydraulic interconnection that presents no essential obstruction for the pressure equalization between the first and the second working chambers, and where especially no throttle element is arranged, i.e. no element which arbitrarily increases the hydraulic resistance.
Optionally, a third externally controllable hydraulic valve V3 is provided, which ensures a throttled fluid passage between the first working chambers 14 and the second working chambers 15. As explained above, the throttle effect can be based on the valve V3 itself, or a narrower piping and/or from regular piping with a built-in throttle 21 connected in series with the valve.
During normal operation, the first working chambers 14 are filled with hydraulic fluid under pressure, all valves are closed, and the hydraulic pump stands preferably still. The brake linings 16 are thus kept in their opened position, without special energy expenditure being necessary, for there is no need for more than an energization of the valves keeping the valves in their closed position.
In order to cause the application of the brake as quickly as possible, (preferred) the control 10 of the elevator car opens the valve V1 and V4 so that the hydraulic pressure collapses in the working chambers 14 by means of a pressure equalization between the working chambers 14 and 15, taking place via the valve V1 and V4 (hydraulic actuators 11.1). After the pressure equalization has taken place, the brake lining or linings 16 are pressed against the rail and/or an elevator car guide rail 2 with maximum force given by the spring element or elements 17, thus the brake responds in a very short period of time with its nominal brake force, i.e. with its maximum brake force.
In order to cause a delayed application of the brake (for example to arrest the car when being landed without generating audible noise), the control 10 of the elevator car only opens the valve V3. Therefore the pressure between the first and the second working chambers 14, 15 is released only in a delayed manner, the time course of the pressure reduction is specified here by throttle 21. This results in the fact that the brake applies in a delayed manner without producing audible noise.
The valve V2 can be used to further influence the speed with which the brake applies, if necessary:
The valves V1 and V3 (if available) remain closed. The valve V2 is opened, the hydraulic pump 19 is activated simultaneously or before.
Theoretically, the hydraulic pump 19 can, among other things, also be used in such a way that it develops a certain pumping effect in the direction of the working chambers 14 which, however, is only so big that the leakage flow of the hydraulic fluid which has been displaced by the effect of a spring element 17 from the corresponding working chamber 14 is bigger than the pumping effect so that the speed with which the hydraulic fluid is displaced from the corresponding working chamber 14 can be controlled or regulated via the current delivery rate of the hydraulic pump in order to influence the speed or force which the brake applies. The hydraulic pump is then preferably operated oscillatingly around the area where the leakage flow of the hydraulic fluid, which the corresponding spring element tries to push back via the pump, is in balance with the flow of the hydraulic fluid so that the pump speed only has to be reduced a little bit for the current reduction of the brake force, and has to be increased a little bit for the current increase of the brake force.
Precondition for such an operation mode is the use of a pump that shows a non-neglectable leakage when being not driven or when being driven with reduced power.
In the case of high quality hydraulic pumps, and especially piston pumps, the leakage flow will be too little in order to be able to let the hydraulic pump influence the speed with which the hydraulic fluid is displaced from the corresponding working chamber 14 in the described manner. As an alternative, the hydraulic pump is then alternately used as a pump driven by the electric motor in conveying direction, or as a "hydraulics motor" which drives the electric motor - maybe in generator mode - that means in the opposite direction of the conveying direction during pump operation. By means of corresponding electric wiring of the motor running as a generator, the torque can be set against which the "hydraulic motor" has to work and/or the revolutions per minute of the "hydraulic motor" can be set. All this influences the speed with which the brake applies.
For this purpose, a speed-controlled, or better speed-regulated motor is used for driving the hydraulic pump. The hydraulic pump is preferably operated oscillatingly around the area where the leakage flow of the hydraulic fluid which the corresponding spring element tries to push back via the pump is in balance with the flow of the hydraulic fluid so that the pump speed only has to be reduced a little bit for the current reduction of the brake force, and has to be increased a little bit for the current increase of the brake force. Thus, the force with which the spring element or elements 17 press the brake lining or linings 16 against the rail can be counteracted more or less so that the current brake force can be controlled or regulated quite well.
Where appropriate, the valve V2 can furthermore dispense with the valve V3. This can take place either actively by means of the hydraulic pump being specifically controlled in the described manner in such a way that the pressure balance between the chambers is slower. Where appropriate, in the case of corresponding design of the hydraulic pump, this can also take place passively, by means of the leakage flowing via the pump.
It is worth to be mentioned that it may be advantageous to operate the hydraulic pump that way that it pumps the hydraulic fluid actively from the working chambers 14 into the working chambers 15, and thus ensures an even quicker application of the brake with maximum brake force - compared to the mere hydraulic "short-circuit" by opening the valve V1.
It should be mentioned that an elevator car brake unit according to the embodiment of
Two of the elevator car brake units shown in
In order to realize a certain redundancy, two or more synchronously operated actuators 11.1 and 11.2 are used here. The possibility of a cascaded operation of the actuators 11.1 and 11.2 is not provided here, where it is especially about an efficient manufacturing for large series, but can be useful, if necessary.
The valve used has also been optimized with regard to costs for this execution example. There is also an externally controllable valve VI, which hydraulically short-circuits the first working chambers 14 and the second working chambers 15 of the hydraulic actuators in its open condition, i.e. ensures a hydraulic connection which does not considerably impede the pressure between the first and the second working chambers. The valve V1 will always be operated, if the brake is to be applied more quickly. The valve V2 is responsible for the slower application of the brake. As soon as the latter is opened, the forces of the spring element or elements 17 press hydraulic fluid as leakage flow along the pump organ of the hydraulic pump 19, or via the pump which is alternatively currently operated as "hydraulic motor" in the direction of the chamber 15. Depending on the revolutions per minute with which the pump runs, it influences the speed of the stream of hydraulic fluid that flows from the chamber 14 into the chamber 15. The speed of brake application and, where applicable, the current brake force can be regulated or controlled in the same way as described above.
With regard to
The elevator car brake unit comprises a hydraulic control block 22.
Ideally, all hydraulic components are located in control block 22 and/or are directly flanged to it without using a hose. It is best, if also the brake calliper is an integral part of the control block at least essentially or completely (not represented figuratively). Otherwise, the design corresponds to the following description by means of the figures.
Mostly the hydraulic actuators 11.1 to 11.3 are flanged to one side of the control block 22, in the present case three actuators. They are hydraulically connected directly to the corresponding borings in the complementary contact surfaces of the hydraulic control block 22, preferably via borings in their contact surfaces. The pressure springs 33, which are reached through by the piston rods 31 of the actuators (which cannot be recognized as such in
A fixing bracket 23 is preferably flanged to the adjacent side at an angle of the control block, which carries the actual brake calliper 24 in which the brake linings 16 attached to the brake lining carriers 25 are kept in such a moveable way that they can be placed or pressed against the surface of a rail from two sides.
Together with the actuators 11.1 to 11.3, the control block 22 forms a self-contained hydraulic system, i.e. it carries the hydraulic pump 19 and its drive, and/or motor 18, the valves VI, V2 and, if available, also V3 and V4 (or V23/V34) as well as the pressure equalizing vessel 20. A separate piping is superfluous insofar as all lines necessary for the connection of the individual hydraulic components are shown in the control block by means of suitable borings with the exception of the lines directly leading to the hydraulic pump 19, or directly exiting from it by means of suitable borings. This kind of execution has the advantage that the hydraulic line system is very rigid, unnecessary elasticities, as normally almost inevitably play a role, are mainly avoided. This is especially important where the brake force is to be regulated with the help of the hydraulic pump, or where importance is attached to the fact to be able to create a defined throttled pressure drop by the mere opening of a valve which causes the brake linings to gradually close over a certain, delayed period until the full brake force has been reached after some time.
Preferably, an own electronic control and at least one acceleration sensor are allocated to the control block 22 which, however, is not represented figuratively here. As can be learned from the information above, the current brake force of the elevator car brake unit can be determined and open loop or preferably close loop controlled with the help of the acceleration sensor.
The elevator car brake unit comprising the mentioned components is preferably designed in such a way that it is capable of plug&play at least on the hydraulic side, i.e. only needs a connection to the power supply and to the signaling network, but no installation works on the hydraulic side anymore.
The brake calliper 24 is preferably designed as a box with a baseplate all around the main side of which preferably boundary elements R protrude, cf.
The brake unit is not least characterized in that the brake linings 16 are not mounted slidingly in the brake calliper 24, but are kept flexibly with play to the brake calliper 24.
For this purpose, the brake linings 16 are attached separately, or divided into several partial linings to a brake lining carrier 25, preferably screwed.
As can be seen best in
Hereby, the two eyes 28 of each leaf spring package 27 are designed differently. The eye leading in the direction of the downwards movement (installation according to its scope of use) is designed in such a way that it picks up the retaining screw 29 allocated to it virtually free of play. Therefore big tensile forces can be transferred via this eye, which occur when catching the elevator car. In contrast, the lagging eye in the direction of the downwards movement is designed in such a way that it creates a floating bearing together with the allocated retaining screw 29 in such a way that the leaf spring package 27 can basically deform unhinderedly, while being pressed to the rail without hindering tensile stresses in the direction parallel to the longitudinal axis of the individual leaf springs preventing this, as would be the case with leaf springs which are firmly clamped on both sides by means of retaining screws 29 positioned in the eyes without play.
It can be seen that each of the two brake lining carriers 25 is pinned or - as is the case here - screwed with the help of spring anchoring screws 30 to the leaf spring package preferably in the area of its center so that the brake lining carrier 25 cannot be removed from its leaf spring package 27. As a rule this screwing also absorbs the transverse brake forces, i.e. the forces which occur as a reaction to the braking friction acting between the rail surface and the brake linings.
It is also interesting that each of the brake lining carriers is partly overlapped at its upper and lower front-end margin in the overlap area marked with "U" from the brake calliper 24 and/or the boundary element R of the brake calliper 24, cf.
Up to here the opposite brake lining carriers 25 are "mirrored" identically in construction.
A fundamental difference is the fact that only one of the opposite brake lining carriers 25 is directly impinged with force from the hydraulic actuators 11.1 to 11.3. This brake lining carrier holds the so-called active brake linings.
The three actuators 11.1 to 11.3 can be easily recognized in
The brake lining carrier 25 which is to be impinged directly with the force of the actuators 11 is preferably not connected to the piston rods 31 of the actuators 11. The piston rods 31 can preferably transfer exclusively compressive forces to the rear side of the brake lining carrier 25 not facing the brake linings 16, and the brake lining carrier basically does not transfer any shear forces to the piston rods 31 due to its special position at the leaf spring package 27. Although in contrast to
As has already been mentioned in connection with
Preferably, each piston rod 31 reaches through the pressure spring 33 allocated to it which leans against the brake calliper 24 and/or its boundary element which has been mentioned above with its side not facing the brake lining carrier, and with its other side against a spring plate 34 connected to the piston rod 31.
The opposite brake lining carrier 25 which is not to be impinged directly with the force of the actuators holds the so-called passive brake linings here. It is preferably not rigid, but mounted in the brake calliper 24 (more than just irrelevantly) flexibly with the help of another spring element which has the form of plate spring packages 36. The auxiliary spring unit is dimensioned in such a way that the spring force developed by it keeps the balance with the spring force applied by the main spring unit in a certain position.
The reason for the installation of the auxiliary spring unit is that a rigid mounting of this brake lining carrier would cause the brake to response in such a strong manner that no delayed application ("brake force increasing over a certain, elongated period until reaching the maximum brake force") of the brake force, and certainly no close loop control of the brake force would be possible. In the case of a rigid mounting of the opposite brake lining carrier to the calliper, it would be the case that the volume of the working chamber 14 would practically no longer change from the moment when the brake linings start to touch the rail so that each further increase or reduction of pressure in the working chamber 14 would immediately lead to an external change of the brake force which is not sensibly controllable.
In order to ensure the flexibility of the second brake lining carrier 25, several guide pins are anchored and/or adjustment screws 35 are screwed in its rear side, which reach through the brake calliper 24 and/or its above mentioned boundary element with the side not facing the brake lining carrier. In between there are further pressure spring elements, here in the form of a plate spring package 36 which is slipped onto the adjustment screw 35 allocated to it. Like this the second brake lining carrier can evade against (by overcoming) the increasing tension of the auxiliary spring unit which is preferably created by plate spring packages here. That makes the characteristic line much softer, since little changes in pressure do not longer result in extremely big changes of the brake force.
However, it is remarkable that also the second brake lining carrier 25 is basically attached to a leaf spring package 27, and the forces occurring while braking are transferred completely or at least basically via the leaf spring package 27 to the brake calliper 24, not via the adjustment screws 35. These preferably run with generous play in the brake calliper 24 in order not to interfere with the flexibility of the second brake lining carrier, or to distort it with friction forces. The function of the adjustment screws 35 is basically limited to the fact of keeping the plate spring packages 36 in place and of avoiding with its heads protruding from the brake calliper on the side not facing the brake lining carrier and/or the underlying lock nuts 37 that the brake lining carrier shifts too far with regard to the brake calliper in the direction of the rail and/or guide rail 2 under the influence of the plate spring packages and possibly lugs. Especially the provision of the mentioned lock nuts 37 is convenient, since the position can be set like this.
For sake of completeness, reference is made to the preferably provided adjustable stops 38 which are designed here as stop screws which are preferably to be tightened by means of locking. Like this the distance can be limited by which the second brake lining carrier can evade. Like this it can be ensured, if necessary, that the brake unit shows a sharply rising characteristic line from a certain point on, thus creates a sharply rising brake force with each further pressure increase on the side of the actuators, if applicable.
It has to be pointed out again that the brake which has just been described by means of the figures can also be used as service brake. Then the motor brake which has been necessary so far, mostly in the form of a disc or drum brake which brakes the motor or the drive sheave shaft, is no longer necessary - which at least compensates for a good part of the costs due for the brake provided according to the invention.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.