Lifting cylinder which can be actuated by pressure fluid, preferably for ventilating devices

Abstract

 The invention relates to a lifting clyinder (1) which can be actuated by pressure fluid, preferably for the opening and closing of ventilating devices such as ventilation flaps for example, having a working piston (6) which is disposed on a longi­tudinally movable lifting rod (8) and is guided for movement in a working pressure chamber (5) comprising a pressure-fluid inlet and having a detent member (13) which is aligned perpendicular to the longitudinal axis (9) of the lifting rod and can be spring loaded, to lock the lifting rod in the end stroke position. The lifting rod has a contact member (17) which is loaded by a spring (22) and which can be supported against a stop (21) in an intermediate stroke position and can be transferred, by an end stroke movement overcoming the action of the spring (22), into its end stroke position when a preset operating pressure is exceeded. In a further embodiment a pair of working pistons (6.1, 6.2) (Fig. 2) on a common lifting rod (8) is movable to an end stroke position over­coming the action of a telescopic spring stop (21).

Description

[0001] The invention relates to a lifting cylinder which can be actuated by pressure fluid, preferably for opening and closing ventilating devices such as ventilating flaps for example, in a construction according to the preamble to claim 1.

[0002] Lifting cylinders of the above-mentioned kind which can be actuated by pressure fluid are used, for example, for closing and opening ventilating devices, ventilating flaps, natural-lighting elements and the like in the roof and wall region of halls and the like. In a known lifting cylinder of the kind mentioned at the beginning, which can be actuated by pressure fluid (EP-A-87 30 2404.6), the lifting rod is adapted to be locked in each of two stroke end positions by means of a detent member which can be actuated by pressure fluid. The building and construction expense necessary for this is consider­able and involves a large number of individual com­ponents. In this cylinder, the locking in the res­pective end positions is effected even during normal operation for interior ventilation although here locking is generally not necessary, for example for safety reasons.

[0003] Ventilating devices additionally also serve as fire-protection elements so that lifting cylinders of the kind mentioned at the beginning, which can be actuated by pressure fluid, are often also coupled to a device for automatic pressure actuation in case of fire, which device comprises a small glass flask which bursts for example when a critical operating temperature is exceeded, and a dischargeable compressed-air cartridge, so that in case of fire, the ventilating flaps can be forcibly transferred into the open position by means of the lifting cylinder after the compressed-air cartridge has been discharged. In this case, it is necessary to lock the lifting cylinder in its end position in order to maintain the automatic ventilation in the event of any destruction of the supply of pressure fluid. Apart from ventilating devices however, fire alarms generally also have to perform an important and decisive safety task in case of fire. In the case of fire-protection ventilation devices which can be actuated by lifting cylinders of conventional type, however, it may happen, as a result of the immediate automatic ventilation in case of fire, that fire alarms responding to smoke do not give any alarm signal.

[0004] It is the object of the present invention to provide a lifting cylinder of the kind mentioned at the beginning which can be actuated by pressure fluid, which is simple to handle and inexpensive, whereby ventilation flaps can be transferred reliably into their open and closed position but with which, at the same time, assurance is provided that, in the event of a disaster, taking into consideration the response behaviour of a smoke detector for example, an optimum control of the flaps from the safety point of view can be effected while retaining the possibility of locking the flaps in their end position.

[0005] In order to solve this problem, the lifting cylinder of the kind mentioned at the beginning which can be actuated by pressure fluid is distinguished by the features given in the characterising part of claim 1. With regard to important further advan­tageous developments of the invention, reference should be made to claims 2 to 13.

[0006] The lifting cylinder according to the inven­tion, which can be actuated by pressure fluid, is an inexpensive device which is simple to handle and which, with only a small number of components which are not susceptible to wear, is in a position to bring the ventilating flaps for example reliably into their open and closed positions, while the inter­mediate stroke position can be used as the lifting-rod end stroke position during normal operation for the daily supply of air to and removal of air from interior spaces. This intermediate stroke position can likewise be used, for example on an outbreak of fire, at first only to open the flaps, for example up to one or two thirds for a certain period of time or, by appropriate connection with regard to control, up to a moment when fire alarms have given an alarm signal, and only after that to bring the lifting rod, for example by discharge of a further pressure-­fluid cartridge with a higher operating pressure, into the end position and to lock it there. Expensive, separate compressed-air connections, which are extremely susceptible particularly in case of a disaster, are advantageously unnecesary to unlock the detent member, for which purpose an entrainment means may appropriately be provided on the lifting rod, by which means, as a result of the end stroke movement of the lifting rod, a retaining element locking the detent member in its detent position can be transferred into an operating position releasing the detent member or the detent member can be transferred into an actuating position rendering possible the locking of the lifting rod.

[0007] The lifting cylinder according to the invention may have housing members which together define one or preferably two working pressure chambers of working pistons as well as internal guiding spaces. The lifting rod is guided for longitudinal movement inside the housing and its front end is adapted to be connected to a linkage or the like of ventilating flaps to be opened or closed. At least one working piston may appropriately be secured to the rear end of the lifting rod, which end has a surface for the action of pressure which can be acted upon, via the pressure-fluid connection preferably constructed in the rear housing portion, preferably with compressed air as pressure fluid so that the lifting rod can be moved pneumatically. If two working pistons are provided, the working piston provided at the rear end of the lifting rod is preferably the one which is responsible for unlocking the detent member and also for locking the detent rod whereas the further working piston disposed in front of this working piston, bears against the stop in the inter­mediate stroke position.

[0008] A compression spring may be supported on the face of a working piston situated opposite to the surface for the action of pressure so that, after pressure relief, the working piston or the lifting rod can be transferred by means of spring force into the end stroke position in which the ventilating flaps should be closed. In order to lock the lifting rod, a detent member may be provided which is aligned for longitudinal movement perpendicular to the longi­tudinal axis of the lifting rod and can only be moved manually, by means of a ring for example, into an unlocking position, against the force of a spring. In order to retain the detent member in this unlocking position, a preferably disc-shaped retaining member which surrounds the lifting rod and has a collar-­shaped marginal extension may be provided which engages with its front ends in a marginal recess formed in the detent member, to retain the detent member in its detent position. In this case, the lifting rod may appropriately be made movable relative to the retaining element which is formed at the rear by a spring with a spring tension adapted to the operating pressure in case of disaster so that when the discharge pressure of a compressed-air cartridge is present for example, the retaining element is moved, by means of the entrainment means, against the force of the spring while as a result of this movement of the lifting rod, it is transferred into a position in which the front ends no longer engage in the marginal recess in the detent member so that the detent member is unlocked and can engage behind the entrainment means. For this purpose, the retaining element is provided with an internal receiving space which is adapted substantially to the dimensions of the entrainment means so that the latter are disposed in the receiving space.

[0009] With regard to further advantageous develop­ments of the invention, reference should be made to the drawing and the following description. In the drawing, in a diagrammatic view in each case:

FIG. 1 shows, in a longitudinal central section, a first example of embodiment of the lifting cylinder according to the invention with one working piston; and

FIG. 2 shows, in a longitudinal central section, an example of embodiment of the lifting cylinder according to the invention, with two working pistons.

[0010] In the drawing, parts acting in the same way are provided with the same reference numerals. The lifting cylinder numbered generally by 1 in the detailing shown in Figure 1 has housing portions 2, 3, 4 which, as a whole, define a working pressure chamber 5 and an internal guiding space 7. A lifting rod 8 with longitudinal central axis 9 is guided for longitudinal movement inside the housing and its front end is adapted to be connected to a linkage or the like of ventilating flaps to be opened or closed. Secured to the rear end of the lifting rod 8 is the working piston 6 which is to be acted upon, at its surface 10 for the action of pressure, preferably by compressed air as a pressure fluid via a pressure-fluid connection formed in the rear housing portion 4 and not visible in detail in the drawing, so that the lifting rod 8 is adapted to be transferred pneumatically into a stroke position in which the ventilating flaps are opened. A compres­sion spring, not illustrated in detail, should be supported on the surface 11 situated opposite to the surface 10 for the action of pressure so that after the working pressure chamber has been relieved of pressure, the working piston 6 or the lifting rod 8 can be transferred, by means of spring force, into the stroke position illustrated in which the ventilating flaps are closed.

[0011] In order to lock the lifting rod 8, a detent member numbered in general by 13, is provided which is aligned for longitudinal movement perpendicular to the longitudinal axis 9 of the lifting rod and, after the lifting rod 8 has been locked, can only be unlocked manually by means of the ring 14. The detent member comprises a rod portion 15 which is supported via a spring 16. Provided in the rear end region of the lifting rod 8 of the example of embodiment illustrated are a contact member 17 and an entrainment means 19 which in turn comprises a locking marginal extension 18 which extends obliquely outwards. The contact member 17 is supported on the entrainment means 19 via a spring 22. At normal operating pressure of 3 or 6 bar for exmaple, the lifting rod can bear or be supported, via the front end of the contact member 17, against the contact surface 21, forming the stop, of the housing portion 2, in an intermediate stroke position, without the lifting rod being locked. This intermediate stroke position can be varied - in relation to the end travel - by the appropriate geometrical dimensions of the distance between contact surface 21 on the one hand and detent member on the other hand in the example of embodiment shown in Figure 1, or of the distance of the contact member 17 from the front end of the entrainment means 19. In the example of embodiment shown in Figure 1, the end travel is only a few millimetres but may equally well be formed in such a manner that the ventilating flaps are only one or two thirds opened for example, for the more reliable response of a fire alarm in case of fire. In the example of embodiment illustrated in Figure 1, the detent pin 15 of the detent member is moved slightly downwards against the force of the spring by means of the locking marginal extension, in the intermediate stroke position. In this case, the spring 22 is designed in such a manner that, at this operating pressure, the lifting rod still cannot undergo any further movement relative to the contact member 17. This relative movement and hence the compression of the spring 22 is only possible when the preset operating pressure prevails, such as acts on the working piston 6 on the discharge of the compressed air cartridge in a case of disaster for example, so that the lifting rod can undergo its end stroke movement and assumes its end stroke posi­tion. In the course of this end stroke movement, the locking marginal extension 18 of the entrainment means 19 moves beyond the detent so that the detent or the detent pin 15 can engage behind the locking marginal extension 18 under the influence of the force of the spring 16.

[0012] In the example of embodiment shown in Figure 2, the housing portions 2, 3.1, 3.2, 3.3 and 4 together define two working pressure chambers 5.1 and 5.2 and guiding spaces 7.1, 7.2 respectively, in each of which a front working piston 6.1 or a rear working piston 6.2 is guided for longitudinal movement being able to be acted upon by pressure fluid. The working pressure chambers 5.1 and 5.2 are connected to a common pressure-fluid supply numbered in general by 23. From the pressure-fluid supply 23, the working pressure chamber 5.2 is adapted to be acted upon with pressure fluid via its pressure-fluid connection 24 and the working pressure chamber 5.1 is adapted to be supplied with pressure fluid through the con­necting conduits 25, 26, 27. The pressure-fluid connection 24 of the working pressure chamber 5.2 is provided with a non-return valve 28. Furthermore, this working pressure chamber 5.2 also has a con­necting conduit 30 controlled likewise by a non- return valve 29 so that when the pressure-fluid connection 24 is released, the working pressure chamber 5.1 can be connected to the working pressure chamber 5.2 through the connecting conduit 30 and the con­ necting conduits 26 and 27.

[0013] In the example of embodiment illustrated, the pressure-fluid inlet 23 can be connected to a pressure-fluid supply and to, for example, two pressure-fluid cartridges in each of which a pressure fluid is stored with a different pressure level. For the daily normal control of the ventilating flaps with, an operating pressure of 3 bar for example, the control is then effected solely via the working pressure chamber 5.1 and the working piston 6.1 since the non-return valves are designed in such a manner that they only respond to a higher operating pressure of 10 bar for example. At the normal operating pressure, the stroke end position is formed by the intermediate stroke position in which - as illustrated in the drawing - the working piston 6.1 rests against the stop element 21 designed resiliently for example or in the form of a telescopic member with a response behaviour adapted to the operating pressures.

[0014] In case of fire, a first pressure-fluid car­tridge, for example, is adapted to be discharged via actuating elements, for example via bursting glass bulbs and the like piercing units which can be released. The discharge pressure of this first cartridge is selected so that the working piston 6.1 is transferred into the position illustrated and hence the lifting rod is transferred into the intermediate stroke position in which the flaps are only partially opened, for example in a defined one-­third position, in order to ensure that smoke detectors can give a signal. After a certain time for example, for example by connecting an actuating device of a second pressure-fluid cartridge to the signal transmitter of a smoke detector by control means, a pressure medium at 10 bar for example is then released so that the pressure medium can then pass through the non-return valve 28 into the working pressure chamber 5.2 and also, through the connecting conduits 30, 26, 27 into the working pressure chamber 5.1 so that, with compression of the stop element 21 and possibly of the spring 22, the lifting rod 8 can be transferred into its end stroke position while the lifting rod is automatically locked by means of the detent member 13 in a similar manner to that in the example of embodiment shown in Figure 1.

Claims

1. A lifting cylinder (1) which can be actuated by pressure fluid, for opening and closing ventilating devices in particular, such as ventilating flaps for example, having a working piston (6, 6.1, 6.2) which is disposed on a longitudinally movable lifting rod (8) and guided for movement in a working pressure chamber (5, 5.1, 5.2) comprising a pressure-fluid connection (24, 27) and having a spring-loadable detent member (13), which is preferably aligned per­pendicular to the longitudinal axis (9) of the lifting rod to lock the lifting rod in the end stroke posi­tion, characterised in that the lifting rod (8) can be supported against a stop (21) in an intermediate stroke position and, if an operating pressure, which can be preset, is exceeded, can be transferred into its end stroke position.

2. A lifting cylinder which can be actuated by pressure fluid according to claim 1, characterised in that associated with the lifting rod (8) is an entrainment means (19) whereby, as a result of the end stroke movement of the lifting rod (8), a retaining element locking the detent member (13) in its detent position can be transferred into an operating position releasing the detent member (13) or the detent member can be transferred into an actuating position rendering possible the locking of the lifting rod.

3. A lifting cylinder which can be actuated by pressure fluid according to claim 1 or 2, charac­terised in that the lifting rod (8) has two working pistons (6.1, 6.2) disposed spaced apart, and asso­ciated with at least one working piston (6.1) is a stop (17, 21) to support the lifting rod in the intermediate stroke position, and associated with one working piston (6.2) is the entrainment means (19), for releasing or unlocking the detent member.

4. A lifting cylinder which can be actuated by pressure fluid according to claim 3, characterised in that the two working pressure chambers (5.1, 5.2) can be connected to a common pressure-fluid supply (23) and the working pressure chamber (5.2) of the working piston (6.2) comprising the entrainment means (19), has a pressure-fluid connection (24) which can only be released when the preset operating pressure is exceeded.

5. A lifting cylinder which can be actuated by pressure fluid according to claim 4, characterised in that the pressure-fluid connection (24) can be released and shut off via a spring-loaded non-return valve (28).

6. A lifting cylinder which can be actuated by pressure fluid according to any one of the claims 1 to 5, characterised in that the stop (17, 21) is constructed in the form of a spring member or teles­copic member with a selectable response behaviour.

7. A lifting cylinder which can be actuated by pressure fluid according to any one of the claims 2 to 6, characterised in that the retaining element is supported on the lifting cylinder (1) through a spring and the spring is designed in such a manner that the retaining element can only be moved out of the detent position by means of the entrainment means (19) when the preset operating pressure is exceeded.

8. A lifting cylinder which can be actuated by pressure fluid according to any one of the claims 2 to 7, characterised in that the retaining element is constructed in the form of a disc member surrounding the lifting rod (8) and the detent member (13) comprises a marginal recess at its upper end, into which recess a front end region of the retaining element can be introduced to lock the detent member.

9. A lifting cylinder which can be actuated by pressure fluid according to any one of the claims 2 to 8, characterised in that the lifting rod (8) can be locked via the entrainment means (19).

10. A lifting cylinder which can be actuated by pressure fluid according to claim 9, characterised in that the retaining element has a receiving space adapted substantially to the dimensions of the entrain­ment means (19).

11. A lifting cylinder which can be actuated by pressure fluid according to any one of the claims 2 to 10, characterised in that the entrainment means (19) is preceded by a contact member (17) which is supported on the entrainment means (19) through a spring.

12. A lifting cylinder which can be actuated by pressure fluid according to claim 9, characterised in that the entrainment means (19) has a collar-shaped locking marginal extension (18) which extends obliquely outwards and behind which the detent member (13), which can only be unlocked manually, can be locked.

13. A lifting cylinder which can be actuated by pressure fluid according to any one of the claims 1 to 12, characterised in that at least one working piston (6. 6.1, 6.2) can be acted upon by a return spring.

Drawing