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(11) | EP 4 253 755 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
| published in accordance with Art. 153(4) EPC |
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| (54) | HYDRAULIC UNIT WITH SEQUENTIAL PISTON PUMPS OPERATED BY ROLLING WEIGHTS |
| (57) The present patent refers to a hydraulic unit (U) that uses at least one rolling
weight (8) having radial movement, connected to a drive shaft (3) moved by at least
one servomotor (1), in order to exert the force, favoured by the action of gravity,
on the hydraulic pistons (11) of sequential pumps positioned on a circular track (12),
which force can be enhanced by the activation of a pneumatic cylinder (13), the speed
of the servomotor (1) or the quantity of rolling weights (8), thereby obtaining volumes
of pressurized hydraulic oil, using small/low-power electric motors. |
Introduction
[0001] The present patent refers to a hydraulic unit, compact in size, to pump a large volume of pressurized oil with low consumption of electric energy, by the fact that the pumps, in sequential and radial alignment, have their hydraulic pistons positioned on a circular track submitted for action of at least one rolling weight that exerts a force, making use of the force of gravity, and works with at least one servomotor and at least one pneumatic cylinder, which works without consuming compressed air, which is used to increase the force of said rolling weight in disk form, thus pumping hydraulic oil, in a process that involves suctioning oil from the reservoir, accumulating a given volume in a chamber of the hydraulic piston and thereafter displacing said volume of oil, with the action of the rolling weight to the output connection at a great pressure.
Field of application
[0002] The field of application of the present invention is all equipment that utilizes hydraulic oil to move actuators and hydraulic motors of any nature.
Fundamentals of the technique
[0003] Conventional hydraulic units are made up of a large reservoir of oil and a hydraulic pump, which can be piston, gear or vane, and which are driven by a hydraulic motor, which will vary in power and size in accordance with the desired hydraulic pressure and flow rate, and same works in a continuous regime, not ceasing to operate even when the hydraulic actuators are at rest, being a generating source of much noise, heat, vibration and oil spillage.
[0004] It is known to person skilled in the art that conventional hydraulic units present good performance during their work regime, but consume much electric energy when it is necessary to displace large volumes of oil at high pressures.
Problems to be solved
[0005] Some limitations of conventional hydraulic units are listed below:
Vibrations - hydraulic units are generators of vibrations caused by the constant friction of the pistons that rub metal against metal and also have the electric motor turning without stopping, and also acting as a source of heat generation.
Electric motor - works the whole time, even when the actuators are at rest, and act this way because they need to maintain the hydraulic pressure of the system and compensate the leakages generated by the gap in the pistons that move rubbing metal against metal. Besides consuming a lot of electric energy, this continuous operation produces heat continuously.
Noise - conventional hydraulic units use pumps that constantly rub their mechanical parts, generating noise which reaches high levels of loudness.
Need for large volume of oil in the reservoir - a high volume of oil is used in the attempt to dissipate the heat generated by the moving parts of the pump, besides using many accessories, such as a heat exchanger.
Heat generation - the heat generated mainly by the friction between the moving parts of the hydraulic pump, and also by the electric motor, which remain in constant operation, even when the hydraulic actuators are at rest.
[0006] This heat produced, besides being a nuisance to the environment, decreases the useful life of the sealings and alter the viscosity of the hydraulic oil, which added to the vibrations, cause leakages in the system.
State of the art
[0007] The current state of the art anticipates some patent documents that address the subject matter at hand, such as US 4277228, entitled "Radial piston pump", which describes a radial piston pump comprising a housing bounding a suction chamber and at least one valve piston unit mounted in the housing. The valve piston unit includes a pressure valve defining a pressure chamber, a movable piston having an axial passage operatively communicating the suction chamber with the pressure chamber and a suction valve located in the axial passage of the piston. The suction valve is actuated for opening and closing the axial passage of the piston so as to establish and interrupt the above communication, respectively. The piston performs a suction stroke and a working stroke, and a component of the suction valve is open during the suction stroke of the piston. The valve component has such a mass that it is opened by an accelerative force produced during the above suction stroke of the piston. The piston is driven by an eccentric mounted on a rotatable shaft, which eccentric has a circumferential groove operatively communicating the suction chamber with the axial passage of the piston.
[0008] The document cited above proposes a solution of raising the degree of filling and improving the opening conditions of the suction valve, by using a spring with a low coefficient of elasticity and a weight whose mass is sufficient to keep it open.
[0009] Document US 8142170 entitled "Radial piston pump" - describes a radial piston pump having external loading.
[0010] The radial piston pump has an inner eccentric, which is attached to a rotatable driveshaft, a cylinder block which has positionally fixed cylinder bores aligned radially with respect to the driveshaft, and displacement pistons which are mounted in a longitudinally movable manner in the cylinder bores.
[0011] The positioned pistons have a piston head with a short housing height, and are mounted with their piston base on the eccentric, in such a way that the piston head, during its longitudinal movement, rotates in a predetermined angle range about the longitudinal central axis of the associated cylinder bore, performing continuous oil suction and pumping.
Aims of the invention
[0013] It is an aim of the present invention to propose a compact hydraulic unit, with savings of up to 90% in electric energy and of great efficiency, which due to the action of at least one rolling weight in the hydraulic pistons of the sequential pumps is capable of moving large volumes of pressurized hydraulic oil, using electric motors of small/low-power;
It is an aim of the present invention to propose a hydraulic unit whose displacement of large volumes of hydraulic oil can be enhanced by the pressure exerted by a pneumatic cylinder in the conductor shaft of the rolling weight, and also by accelerating the servomotor;
It is an aim of the present invention to propose a hydraulic unit that uses the force of gravity to assist the force exerted on the pneumatic cylinders of the sequential pumps;
It is an aim of the present invention to propose a hydraulic unit that operates at least one pneumatic cylinder without consuming compressed air;
It is an aim of the present invention to propose a safe hydraulic unit, capable of instantaneously depressurizing the hydraulic pressure of the system in cases of emergency, when the need arises;
It is an aim of the present invention to propose a hydraulic unit capable of reducing by up to 90% the volume of oil required to operate in the reservoir, whereby reducing environmental impacts caused by large volume reservoirs which have spillages that ultimately contaminate the soil;
It is an aim of the present invention to propose a hydraulic unit that displaces solely the volume of oil that will be used;
It is an aim of the present invention to propose a hydraulic unit capable of significantly reducing the noise compared to conventional hydraulic units;
It is an aim of the present invention to propose a hydraulic unit that does not generate heat like conventional hydraulic units, which increases the useful life of the sealing elements, reducing stoppages for maintenance;
It is an aim of the present invention to propose a hydraulic unit that does not produce vibrations like conventional hydraulic units;
It is an aim of the present invention to propose a hydraulic unit having optimal benefit-cost ratio.
Summary of the invention
[0014] The operation of the hydraulic unit claimed in this patent is based on at least one rolling weight, in disk form, of known magnitude, with a central bore housing the bearings of a pillow block, and fastened at the end of a conductor shaft, which works in horizontal position, the aim of which is to exert a radial force to push and move the rolling weight making it shift in a radial direction, on a circular track, so in a circumferential trajectory, with at least one pneumatic cylinder, pushing this rolling weight against the hydraulic piston of a given sequential pump and consequently on a circular track in order to increase the force applied. In moving radially, the rolling weight will drive the various sequential pumps, whose hydraulic pistons return by action of a spring, which are distributed throughout the perimeter of the circular track mentioned above, displacing under pressure a volume of oil which is at rest in the hydraulic chamber of each hydraulic piston, wherein after passing through a given piston and continuing their displacement to the subsequent piston, continually and sequentially, by the retractile action of the initially compressed spring, when returning to its rest position, obliges the piston to go upward, performing the work of suctioning the oil from the reservoir, storing this oil in the hydraulic chamber of the hydraulic piston per se, which should remain in waiting until the rolling weight passes by it again and moves this accumulated oil, which added to the other hydraulic pistons represents a high volume of pressurized oil. The rolling weight and respective conductor shaft are driven by at least one servomotor, which may have its speed altered and controlled, as required.
Description of the drawings
[0015] The invention will next be described in its embodiment form, and for improved understanding, references will be made to the accompanying drawings, in which the following are represented:
FIGURE 1: Side cutaway view of the hydraulic unit with sequential piston pumps operated by rolling weights;
FIGURE 2: Top view of the hydraulic unit with sequential piston pumps operated by rolling weights;
FIGURE 3: Enlarged side cutaway view of the driving mechanism of the rolling weight of the hydraulic unit with sequential piston pumps operated by rolling weights, with detail of the hydraulic check valve;
FIGURE 4: Schematic cutaway view illustrating the action of the rolling weight on the hydraulic pistons of the hydraulic unit with sequential piston pumps operated by rolling weights;
FIGURE 5: Schematic cutaway view illustrating the sporadic action of the rolling weight on a hydraulic piston of the hydraulic unit with sequential piston pumps operated by rolling weights;
FIGURE 6: Schematic top cutaway view illustrating the movement direction of the rolling weight on the hydraulic pistons of the hydraulic unit with sequential piston pumps operated by rolling weights;
FIGURE 7: Schematic side cutaway view of the connection of the hydraulic unit with sequential piston pumps operated by rolling weights, in the user's hydraulic valve manifold block;
FIGURE 8: Schematic side cutaway view of the hydraulic pressure relief mechanism of the hydraulic unit with sequential piston pumps operated by rolling weights.
Detailed technical description of the invention
[0016] The hydraulic unit with sequential piston pumps operated by rolling weights refers to a hydraulic unit (U) that uses at least one rolling weight (8) having radial movement, connected to a drive shaft (3) driven by at least one servomotor (1), in order to exert the force, favoured by the action of gravity, on the hydraulic pistons (11) of sequential pumps positioned on a circular track (12), which force can be enhanced by the action of a pneumatic cylinder (13), the speed of the servomotor (1) or quantity of rolling weights (8), thereby obtaining volumes of pressurized hydraulic oil, using small/low-power electric motors.
[0017] More particularly, the hydraulic unit (U) claimed comprises at least one upper servomotor (1) driving a speed reducer (2) which has the function of turning a drive shaft (3), in the vertical position, supported and guided on an upper bearing (4) and on a lower bearing (5). From the drive shaft (3) derives at least one conductor shaft (6), fastened thereto on a swivel joint (7) which gives it a certain freedom of movement, at the distal end thereof there is prominently at least one rolling weight (8) in disk form, of known magnitude, seated on bearings (10), to the extent that upon turning, said rolling weight (8) will exert a force, making use of the action of gravity, on the hydraulic pistons (11) of the sequential pumps supported on a circular track (12). The force exerted on the hydraulic pistons (11) may also be enhanced by the action of at least one pneumatic cylinder (13) mounted at the end of a support (14) equally connected to the drive shaft (3), and by the very rotation of the servomotor (1). The process exerted by the invented hydraulic unit involves suctioning oil from the reservoir (15) and when the rolling weight (8) passes by the hydraulic piston (11) it displaces the volume of oil accumulated in its chamber (16) to the hydraulic ring (17), pressure chamber (18), output connection (19) and external connection (20) to the user's manifold (21) at a high pressure and flow rate.
[0018] Operationally, the support (14) of the pneumatic cylinder (13) and the conductor shaft (6) of the hydraulic pistons (11) rotate in solidarity with each other around the drive shaft (3) travelling the circuit of the circular track (12). Accordingly, the rolling weight (8) is guided in a radial direction and is displaced, supported by the bearings (10) in a continuous trajectory of 360º. The rolling weight (8), as already mentioned, has the function of acting as a force applied, by gravity, on the hydraulic pistons (11) with the aim of forcing them downwards and displacing the volume of oil that is accumulated in the chamber (16). The enhancement of the force applied, increased or decreased by means of the pneumatic cylinder (13) occurs by action of a pneumatic directional valve (22) which is powered by a source of compressed air (23), and which has the function of directing compressed air to the upper pneumatic chamber (24), or to the lower pneumatic chamber (25), depending on the work intended to be carried out. When the servomotor (1) begins to rotate, it moves the speed reducer (2) and makes the drive shaft (3) turn, which is fastened in the vertical position, and with it the rolling weight (8) by means of the conductor shaft (6) which is positioned horizontally, and at the same time the pneumatic cylinder (13) which thereafter receives the compressed air in the upper pneumatic chamber (24) causing it to advance, resulting in a force applied on the rolling weight (8). As the drive shaft (3) begins to turn the assembly, the rolling weight (8) begins to move on the track (12) of the assembly of sequential pumps and respective hydraulic pistons (11). As the rolling weight (8) reaches the centerline of the shaft of the hydraulic piston (11), it moves downwards compressing the spring (26) of the hydraulic piston (11) and displacing the volume of oil that is in the chamber (16) to the pressure chamber (18) of the hydraulic ring (17), through the guide pipe (27) of pressurized oil, after opening the hydraulic check valve (28). In continuing its trajectory rolling on the hydraulic pistons (11), the rolling weight (8) begins to come out of the top of the hydraulic piston (11) and at this point the spring (26) begins the displacement thereof upwards, suctioning hydraulic oil from the reservoir (15) through the suction pipe (29). The hydraulic output pressure is the result of the force applied on the area of the hydraulic piston (11), and this force is the magnitude of the rolling weight (8) added to the force exerted by the pneumatic cylinder (13), and this force of the pneumatic cylinder (13) may vary up or down, in accordance with the regulated pneumatic pressure, which can be controlled at the source of compressed air (23). The rolling movement of the rolling weight (8) does the continuous work of displacing the volume of oil from the hydraulic chamber (16) of the piston, whose total volume is displaced is the sum of the quantity of hydraulic pistons (11) existing on the circular track (12), and this quantity may vary to more or to less, according to the configuration thereof. Another factor that contributes to obtaining a greater or lesser volume of displaced oil in one full turn around the perimeter of the circular track (12) and respective hydraulic pistons (11) is the quantity of rolling weights (8) placed in the configuration to drive the pumping, besides the variation of the rotation of the servomotor (1), which may vary to more or to less, resulting in a greater or lesser volume of oil displaced in a given time period. Considering that the rolling weight (8), which is the force applied on the hydraulic pistons (11), and the rotation of the drive shaft (3) as well, the oil pumping process will begin with the force of the rolling weight (8) being applied to the hydraulic piston (11), making the oil stored at rest in the hydraulic chamber (16) of the piston to begin to move and start to open the hydraulic check valve (28), allowing this oil to move through the guide pipe (27) of pressurized oil and to reach the hydraulic ring (17) continuing to move through its pressure chamber (18), reaching the output connection (19) of the hydraulic ring, passing through the hydraulic oil output pipe (30) arriving at the external oil pressure connection (17) and being conducted to the user's manifold block (21), where it will be used to perform the works according to the cycle programming of each equipment.
[0019] The hydraulic unit (U) has a safety system that enables the instantaneous hydraulic depressurization of the system wherein, by means of an external command, from some emergency device, the position of the pneumatic directional valve (22) is changed, causing the pressurized air, which was applied to the upper pneumatic chamber (24) now to act upon the lower pneumatic chamber (25) and as a result raises the rolling weight (8) by means of the its conductor shaft (6), which is fastened to the swivel joint (7), making all the hydraulic pistons (11) return to the rest position, which occurs with the decompression of the spring (26), causing the pressure of the hydraulic system to drop to zero, even if the servomotor (1) continues to rotate out of inertia for some moments before it comes to a complete stop.
[0020] The pressurized hydraulic oil which leaves though the external oil pressure connection (17) is conducted, through hydraulic hoses or pipes, directly to the user's manifold block (21), and can be used according to the user's equipment cyclogram without the need of creating an electronic interface with the equipment that will receive the pressurized hydraulic oil.
REFERENCES CITED IN THE DESCRIPTION
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.
Patent documents cited in the description