Hydraulic circuit
The hydraulic circuit addresses the need for efficient pressure management by using a check valve system with controlled fluid flow paths and leakage management, minimizing lines and enhancing operational efficiency.
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Patents
- Current Assignee / Owner
- THOMAS SA
- Filing Date
- 2024-07-29
- Publication Date
- 2026-07-01
Smart Images
Figure IMGF0001 
Figure IMGF0002 
Figure IMGF0003
Abstract
Description
[0001] The invention relates to a hydraulic circuit. State of the art
[0002] Hydraulic systems for pressure build-up and pressure release consist of a high-pressure port, a low-pressure port, a feed unit, a pump, and a non-return valve. In the first state, fluid is drawn in by the pump via the feed unit and the low-pressure port and conveyed through the non-return valve to the high-pressure port. This creates pressure at the high-pressure port. In the second state, the fluid is conveyed via the feed unit and the low-pressure port to a control port of the non-return valve. This allows fluid to flow from the high-pressure port through the non-return valve in the closed direction. This creates pressure release at the high-pressure port. In the second state, the fluid is conveyed to the control port of the non-return valve until a predefined pressure is reached at the control port. However, little to no fluid flows through the control valve.The pump can only reliably maintain pressure as long as it is pumping fluid. Therefore, to maintain pressure at the control valve, the pump must continuously deliver fluid. An additional line is currently required to discharge the excess fluid. This additional line is located between the pump and the control port of the check valve.
[0003] A hydraulic circuit with a pump and a check valve is known from WO2023 / 152634.
[0004] The object of the invention is to provide a hydraulic circuit which allows targeted pressure build-up and pressure reduction at a high-pressure connection and minimizes the number of fluid lines of the hydraulic circuit.
[0005] This problem is solved by a hydraulic circuit according to independent claim 1.
[0006] The hydraulic circuit comprises a high-pressure port, a low-pressure port, a feed unit, and a pump system. The low-pressure port is fluidically connected to the high-pressure port via a series connection of the feed unit and the pump system. The pump system includes a pump for conveying a fluid, a shaft for driving the pump, and at least one unlockable check valve system. The pump is configured to, in a first state, convey the fluid from a first pump port to a second pump port, and in a second state, convey the fluid from the second pump port to the first pump port. The check valve system is fluidically connected to the second pump port at one valve port and to the high-pressure port at the other valve port.The check valve system is designed to prevent fluid flow from the second valve port to the first valve port and to allow fluid flow from the first valve port to the second valve port. The check valve system includes a control port through which fluid flow from the second valve port to the first valve port can be enabled. The hydraulic circuit is designed to enable fluid flow from the second valve port to the first valve port via the control port when the pump is in the second state. The feed unit is configured to allow fluid flow from the low-pressure port to the first pump port in the first pump state and to prevent fluid flow from the second pump port to the low-pressure port.The feed unit is configured to allow fluid flow from the low-pressure port to the second pump port in a second pump state, while preventing fluid flow from the first pump port to the low-pressure port. During fluid delivery, the pump exhibits a leakage flow towards the shaft. The shaft is connected to the low-pressure port via a pressure equalization line to discharge the fluid from the shaft. Alternatively or additionally, the check valve system exhibits a leakage flow between the control port and the first valve port when the pump is in the second state.
[0007] In the first state, fluid is drawn in from the low-pressure port via the first pump port and delivered to the first valve port via the second pump port. The feed unit prevents backflow of fluid from the second pump port to the low-pressure port. The fluid is then conveyed through the check valve system to the second valve port and the high-pressure port. Thus, in the first state, fluid is delivered from the low-pressure port, through the pump and the check valve system, to the high-pressure port, increasing the fluid pressure at the high-pressure port. This allows fluid to be actively and controllably supplied to the high-pressure port by controlling the pump. If the pump stops delivering fluid, no more fluid flows from the low-pressure port, through the pump and the check valve system, to the high-pressure port.The check valve system prevents fluid from flowing back from the high-pressure port through the pump to the low-pressure port.
[0008] In the second state, fluid is drawn in from the low-pressure port via the second pump port and conveyed through the first pump port to the control port of the check valve system. The feed unit prevents backflow of fluid from the first pump port to the low-pressure port. Due to the pressure build-up at the control port, the check valve system allows fluid flow from the high-pressure port, through the second valve port, the check valve system, and back to the first valve port. Thus, fluid can be actively and controllably discharged from the high-pressure port by controlling the pump, thereby reducing the fluid pressure at the high-pressure port.
[0009] During pump operation, a portion of the pumped fluid leaks out within the pump and / or the check valve system. The leakage within the pump reaches the pump shaft and is discharged to the low-pressure port via a pressure equalization line. The leakage from the check valve system reaches the low-pressure port via the first valve port. This leakage allows the pump to operate normally and maintain pressure at the control port without damaging the pump. Furthermore, no additional line is required to discharge the fluid during pressure build-up and maintenance at the control port. The pumped fluid used to build pressure at the control port is discharged to the low-pressure port via the leakage and / or the pressure equalization line. Since leakage occurs in every operating state of the pump, a pressure equalization line is necessary anyway.Therefore, no line is required between the first pump connection and the control connection. This reduces the complexity of the hydraulic circuit.
[0010] The dependent claims preferably describe further developments of the invention.
[0011] Preferably, the check valve system includes at least one first check valve. The first check valve is connected to the first valve port at a first check valve port and to the second valve port at a second check valve port. The first check valve is configured to prevent fluid flow from the second check valve port to the first check valve port and to allow fluid flow from the first check valve port to the second check valve port. This allows for efficient pressure build-up at the high-pressure port in a first state, since no further hydraulic elements are arranged between the first and second valve ports that would present hydraulic resistance.
[0012] Preferably, the first check valve is designed to be unlocked. The first check valve has a first control port through which fluid flow from the second check valve port to the first check valve port can be enabled. The first control port is fluidically connected to the control port. Thus, the function of the check valve system can be implemented using a single check valve, and the system complexity of the hydraulic circuit can be kept low.
[0013] The check valve preferably comprises a cylinder, a piston, and a check element. In a third state, the check element prevents fluid flow from the second check valve port to the first check valve port. In a fourth state, the check element allows fluid flow from the second check valve port to the first check valve port. The piston is configured such that when fluid flows into the cylinder via the control port and pressure builds up in the cylinder, the piston moves in a first direction, moving the check element into the fourth state. The check valve allows a leakage flow between the check valve control port and the first check valve port through the cylinder.The above design of the displacement and piston eliminates the need for an additional line to remove the leakage flow. This simplifies the construction of the hydraulic circuit.
[0014] Advantageously, the check valve system has at least one first throttle. The first throttle is directly connected to the second valve port. The first check valve and the first throttle are fluidically connected in series. This allows for a slower fluid flow from the high-pressure port, through the throttle, and the check valve system. Due to the slower fluid flow, the flow rate and thus pressure reduction at the high-pressure port can be more easily controlled.
[0015] The check valve system advantageously features at least a second check valve and a third valve port. The third valve port is fluidically connected to the second pump port. The second check valve is fluidically connected to the third valve port via a third check valve port and to the second valve port via a fourth check valve port. The second check valve is configured to prevent fluid flow from the fourth check valve port to the third check valve port and to allow fluid flow from the third check valve port to the fourth check valve port.
[0016] Thus, in the check valve system, a first hydraulic path, between the first and second valve ports, and a second hydraulic path, between the third and second valve ports, can be designed separately. The second hydraulic path allows fluid flow only through the second check valve to the second valve port and the high-pressure port, thereby creating pressure at the high-pressure port. Likewise, fluid can be conveyed to the high-pressure port via the first hydraulic path and the first check valve, thus increasing the pressure at the high-pressure port. The parallel arrangement of the first and second check valves reduces fluidic resistance between the second pump port and the high-pressure port, thereby increasing the efficiency of the hydraulic circuit.
[0017] No fluid can be discharged from the high-pressure port via the second hydraulic path, thus preventing pressure reduction. In the second state, the first hydraulic path allows fluid to flow from the high-pressure port through the first unlockable check valve to the first valve port, thereby reducing pressure at the high-pressure port. This allows for controlled pressure reduction at the high-pressure port.
[0018] By positioning the first restrictor between the second valve port and the second check valve port, the fluid flow, and thus the pressure drop at the high-pressure port, can be slowed down via the first hydraulic path in the second state. This improves the controllability of the pressure drop at the high-pressure port during the second state. Furthermore, the efficiency of pressure build-up is increased because the fluid can flow from the first pump port to the high-pressure port via the second hydraulic path without having to pass through a restrictor.
[0019] The check valve system preferably includes a third check valve. The third check valve is fluidically connected to a fifth check valve port and to a second valve port, and to a sixth check valve port. The third check valve is configured to prevent fluid flow from the fifth check valve port to the sixth check valve port and to allow fluid flow from the sixth check valve port to the fifth check valve port. The third check valve is arranged fluidically parallel to the first throttle.
[0020] In the first state, fluid flows through the first valve port, the first check valve, and the second valve port, increasing the pressure at the high-pressure port. This fluid flow, between the first check valve and the second valve port, passes partly through the third check valve and partly through the first restrictor. This arrangement presents less fluidic resistance to the fluid flow than if the entire fluid flow passed solely through the first restrictor. This arrangement improved the efficiency of the check valve system. In the second state, the third check valve prevents fluid flow from the fifth check valve port to the sixth check valve port. The entire fluid flow then flows from the high-pressure port, through the second valve port, the first restrictor, the first check valve, and the first valve port.Since the entire fluid flow between the second valve port and the first valve port passes through the first throttle, this entire fluid flow is slowed down. This simplifies control of the pressure reduction at the high-pressure port. Thus, this design allows for both efficient pressure build-up and improved control of the pressure reduction at the high-pressure port.
[0021] Advantageously, the check valve system includes a second throttle, a fourth check valve, and a fifth check valve. The second throttle, the fourth check valve, and the fifth check valve are fluidically arranged between the first check valve and the first valve port. The fourth check valve is fluidically connected to the first check valve port at a seventh check valve port and to the first valve port at an eighth check valve port. The fourth check valve is configured to prevent fluid flow from the seventh check valve port to the eighth check valve port and to allow fluid flow from the eighth check valve port to the seventh check valve port. The fifth check valve is arranged antiparallel to the fourth check valve.The fifth check valve is fluidically connected to the first check valve port via a ninth check valve port and to the first valve port via a tenth check valve port. The fifth check valve is configured to prevent fluid flow from the tenth check valve port to the ninth check valve port and to allow fluid flow from the ninth check valve port to the tenth check valve port. The second restrictor is fluidically arranged between the tenth check valve port and the second valve port, and parallel to the fourth check valve.
[0022] In the first state, the fluid flows from the first pump port, through the fourth check valve and the first check valve, to the high-pressure port, increasing the pressure there. The positioning of the fifth check valve prevents fluid flow through it and thus through the second throttle in the first state. This allows for high efficiency in the first state, as no losses occur through the second throttle. In the second state, the fluid flows from the high-pressure port to the first valve port, through the fifth check valve and the second throttle. The fourth throttle blocks the fluid flow in the second state, and all fluid flows through the fifth check valve and the second throttle. The second throttle slows the fluid flow, making it easier to control the fluid flow in the second state.Thus, in the first state, this embodiment allows for an efficient pressure increase at the high-pressure port, and in the second state, an easily controlled pressure reduction at the high-pressure port.
[0023] The check valve system advantageously features a fourth valve port, a sixth, unlockable check valve, and a third throttle. The fourth valve port is fluidically connected to the low-pressure port. The sixth check valve is fluidically connected to the fourth valve port via an eleventh check valve port and to the second valve port via a twelfth check valve port. The sixth check valve is configured to prevent fluid flow from the twelfth check valve port to the eleventh check valve port and to allow fluid flow from the eleventh check valve port to the twelfth check valve port. The sixth check valve has a second check valve control port through which fluid flow from the twelfth check valve port to the eleventh check valve port can be enabled.The second check valve control port is fluidically connected to the control port.
[0024] In the first state, the fluid flows, at least via the first and second valve ports, to the high-pressure port, increasing the pressure there. No fluid flows through the third restrictor in this state. In the second state, fluid flows from the first pump outlet via the control port to the second check valve control port. This allows the sixth check valve to allow fluid flow from the high-pressure port via the second and fourth valve ports to the low-pressure port, thus enabling pressure reduction. In this state, the fluid also flows through the third restrictor and is slowed down. This improves the controllability of pressure reduction at the high-pressure port without compromising the efficiency of pressure build-up at the high-pressure port.
[0025] Preferably, the hydraulic circuit includes a pressure relief valve. The pressure relief valve is connected to the high-pressure port at a first pressure relief valve port and to the low-pressure port at a second pressure relief valve port. The pressure relief valve is connected in parallel to the pump system and the feed unit via the high-pressure and low-pressure ports. The pressure relief valve opens when there is overpressure at the high-pressure port, allowing fluid to flow directly from the high-pressure port to the low-pressure port until the overpressure at the high-pressure port is relieved.
[0026] The feed unit particularly preferably includes a seventh and an eighth check valve. The seventh check valve is connected to a thirteenth check valve port with a low-pressure connection and to the first pump port at a fourteenth check valve port. The seventh check valve is configured to prevent fluid flow from the fourteenth check valve port to the thirteenth check valve port and to allow fluid flow from the thirteenth check valve port to the fourteenth check valve port. The eighth check valve is connected to a fifteenth check valve port with a low-pressure connection and to the second pump port at a sixteenth check valve port.The eighth check valve is designed to prevent fluid flow from the sixteenth check valve port to the fifteenth check valve port and to allow fluid flow from the fifteenth check valve port to the sixteenth check valve port. This allows the functionality of the feeding unit to be implemented reliably using simple hydraulic components. This reduces the complexity and manufacturing costs of the hydraulic circuit.
[0027] Advantageously, the feed unit is designed as a dual-pressure valve. This reduces the number of components required in the hydraulic circuit and allows for a more compact design of the hydraulic circuit.
[0028] Further details, advantages and features of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawing. It shows: Fig. 1 a schematic representation of a hydraulic circuit according to a first embodiment of the invention, Fig. 2 a schematic representation of a hydraulic circuit according to a second embodiment of the invention, Fig. 3 a schematic representation of a hydraulic circuit according to a third embodiment of the invention, Fig. 4 a schematic representation of a hydraulic circuit according to a fourth embodiment of the invention, Fig. 5 a schematic representation of a hydraulic circuit according to a fifth embodiment of the invention, Fig. 6 a schematic representation of a hydraulic circuit according to a sixth embodiment of the invention, Fig. 7 a schematic representation of a hydraulic circuit according to a seventh embodiment of the invention, Fig. 8 a schematic representation of a hydraulic circuit according to an eighth embodiment of the invention, and Fig.9. A schematic representation of a hydraulic circuit according to a ninth embodiment of the invention. Embodiments of the invention
[0029] Fig. 1 Figure 1 shows a schematic representation of a hydraulic circuit according to a first embodiment of the invention.
[0030] The hydraulic circuit 1 comprises a high-pressure port 2, a low-pressure port 3, a feed unit 4, and a pump system 5. The low-pressure port 3 is fluidically connected to the high-pressure port 2 via a series connection of the feed unit 4 and the pump system 5. The pump system 5 includes a pump 6 for pumping a fluid, a shaft 7 for driving the pump 6, and a lockable check valve system 8. The pump 6 is configured to pump the fluid from a first pump port 6a to a second pump port 6b in a first state, and from the second pump port 6b to the first pump port 6a in a second state. The check valve system 8 is fluidically connected to the second pump port 6b at a first valve port 8a and to the high-pressure port 2 at a second valve port 8b.The check valve system 8 is configured to prevent fluid flow from the second valve port 8b to the first valve port 8a and to allow fluid flow from the first valve port 8a to the second valve port 8b. The check valve system 8 has a control port 8c through which fluid flow from the second valve port 8b to the first valve port 8a can be enabled. The hydraulic circuit 1 is configured to enable fluid flow from the second valve port 8b to the first valve port 8a via the control port 8c when the pump 6 is in the second state. The feed unit 4 is configured to allow fluid flow from the low-pressure port 3 to the first pump port 6a in the first state of the pump 6 and to prevent fluid flow from the second pump port 6b to the low-pressure port 3.The feed unit 4 is configured, in a second state of pump 6, to allow fluid flow from the low-pressure port 3 to the second pump port 6b and to prevent fluid flow from the first pump port 6a to the low-pressure port 3. When pumping the fluid, the pump 6 exhibits a leakage flow towards the shaft 7. The shaft 7 is connected to the low-pressure port 3 by means of a pressure equalization line 9 to discharge the fluid from the shaft 7.
[0031] In the first state, the fluid is drawn in from the low-pressure port 3 via the first pump port 6a and conveyed via the second pump port 6b to the first valve port 8a. The feed unit 4 prevents backflow of the fluid from the second pump port 6b to the low-pressure port 3. The fluid is then conveyed through the check valve system 8 to the second valve port 8b and the high-pressure port 2. Thus, in the first state, fluid is conveyed from the low-pressure port 3 through the pump 6 and the check valve system 8 to the high-pressure port 2, increasing the fluid pressure at the high-pressure port 2. Therefore, fluid can be actively and controllably supplied to the high-pressure port 2 by controlling the pump 6. If the pump 6 stops delivering fluid, no more fluid flows from the low-pressure port 3 through the pump 6 and the check valve system 8 to the high-pressure port 2.A backflow of fluid from the high-pressure port 2, through the pump 6, to the low-pressure port 3 is prevented by the check valve system 8.
[0032] In the second state, the fluid is drawn in from the low-pressure port 3 via the second pump port 6b and conveyed via the first pump port 6a to the control port 8c of the check valve system 8. The feed unit 4 prevents backflow of the fluid from the first pump port 6a to the low-pressure port 3. Due to the pressure build-up at the first control port 8c, the check valve system 8 allows fluid flow from the high-pressure port 2 via the second valve port 8b, through the check valve system 8, and the first valve port 8a. Thus, fluid can be actively and controllably discharged from the high-pressure port 2 by controlling the pump 6, thereby reducing the fluid pressure at the high-pressure port 2.
[0033] During operation of pump 6, a portion of the pumped fluid leaks into pump 6 and / or into the check valve system 8. This leakage flows to the shaft 7 of pump 6 and is discharged to the low-pressure port 3 via a pressure equalization line 9. The leakage from the check valve system 8 flows to the low-pressure port 3 via the first valve port 8a. This leakage allows pump 6 to operate normally and maintain pressure at the control port 8c without damaging pump 6. Therefore, no line is required between the first pump port 6a and the control port 8c, thus reducing the complexity of the hydraulic circuit 1.
[0034] The hydraulic circuit 1 includes a pressure relief valve 19. The pressure relief valve 19 is connected to the high-pressure port 2 at a first pressure relief valve port 19a and to the low-pressure port 3 at a second pressure relief valve port 19a. The pressure relief valve 19 is connected in parallel to the pump system 5 and the feed unit 4 via the high-pressure port 2 and the low-pressure port 3. The pressure relief valve 19 opens when there is overpressure at the high-pressure port 2 and allows fluid flow directly from the high-pressure port 2 to the low-pressure port 3 until the overpressure at the high-pressure port 2 is relieved.
[0035] The feed unit 4 is designed as a dual-pressure valve 22. This reduces the number of components required in the hydraulic circuit 1 and allows for a more compact design of the hydraulic circuit 1.
[0036] Fig. 2 Figure 1 shows a schematic representation of a hydraulic circuit 1 according to a second embodiment of the invention.
[0037] The second embodiment from Fig. 2 is based on similar features to the first embodiment from Fig. 1 .
[0038] Additionally, the check valve system 8 includes a first unlockable check valve 10. The first unlockable check valve 10 is connected to the first valve port 8a at a first check valve port 10a and to the second valve port 8b at a second check valve port 10b. The first unlockable check valve 10 is configured to prevent fluid flow from the second check valve port 10b to the first check valve port 10a and to allow fluid flow from the first check valve port 10a to the second check valve port 10b. This allows for efficient pressure build-up at the high-pressure port 2 in the first state, as no other hydraulic elements are arranged between the first valve port 8a and the second valve port 8b that would present hydraulic resistance.
[0039] The first unlockable check valve 10 has a first check valve control port 10c, through which a fluid flow from the second check valve port 10b to the first check valve port 10a can be enabled. The first check valve control port 10c is fluidically connected to the control port 8c. Thus, the function of the check valve system 8 can be implemented by means of a single check valve 10, and the system complexity of the hydraulic circuit can be kept low.
[0040] Fig. 3 Figure 1 shows a schematic representation of a hydraulic circuit 1 according to a third embodiment. The third embodiment is based on similar features to the second embodiment.
[0041] The check valve 10 has a displacement chamber 10f, a piston 10e, and a check element 10f. In a third state, the check element 10f prevents fluid flow from the second check valve port 10b to the first check valve port 10a. In a fourth state, the check element 10f allows fluid flow from the second check valve port 10b to the first check valve port 10a. The piston 10e is configured such that when fluid flows into the displacement chamber 10d via the control port 8c and pressure builds up in the displacement chamber 10d, the piston 10e moves in a first direction and moves the check element 10f into the fourth state. The check valve 10 has a leakage flow between the check valve control port 10c and the first check valve port 10a across the displacement 10d.The above design of the displacement and piston eliminates the need for an additional line to remove the leakage flow. This simplifies the construction of hydraulic circuit 1. Fig. 4 Figure 1 shows a schematic representation of a hydraulic circuit 1 according to a fourth embodiment of the invention. The fourth embodiment from Fig. 4 is based on similar features to the third embodiment from Fig. 3 .
[0042] Furthermore, the check valve system 8 has a first throttle 11. The first throttle 11 is directly connected to the second valve port 8b. The first check valve 10 and the first throttle 11 are fluidically connected in series. This allows a slower fluid flow from the high-pressure port 2 through the first throttle 11 and the first check valve 10. Due to the slower fluid flow, the fluid flow and thus pressure reduction at the high-pressure port 2 can be more easily controlled.
[0043] The check valve system 8 comprises a second check valve 12 and a third valve port 8d. The third valve port 8d is fluidically connected to the second pump port 6b. The second check valve 12 is connected to the third valve port 8d at a third check valve port 12a and to the second valve port 8b at a fourth check valve port 12b. The second check valve 12 is configured to prevent fluid flow from the fourth check valve port 12b to the third check valve port 12a and to allow fluid flow from the third check valve port 12a to the fourth check valve port 12b.
[0044] Thus, the check valve system 8 can be configured with a first hydraulic path, between the first valve port 8a and the second valve port 8b, and a second hydraulic path, between the third valve port 8d and the second valve port 8b, operating separately. The second hydraulic path allows fluid flow only through the second check valve 12 to the second valve port 8b and the high-pressure port 2, thereby increasing pressure at the high-pressure port 2. Likewise, fluid can be conveyed to the high-pressure port 2 via the first hydraulic path through the first check valve 10, thus increasing the pressure at the high-pressure port 2. The parallel arrangement of the first check valve 10 and the second check valve 12 reduces fluid resistance between the second pump port 6b and the high-pressure port 2, thereby increasing the efficiency of the hydraulic circuit 1.
[0045] No fluid can be discharged from high-pressure port 2 via the second hydraulic path, thus preventing pressure reduction. In the second state, the first hydraulic path allows fluid to flow from high-pressure port 2 via the first unlockable check valve 10 to the first valve port 8a, thereby reducing pressure at high-pressure port 2. This allows for controlled pressure reduction at high-pressure port 2.
[0046] By positioning the first throttle 11 between the second valve port 8b and the second check valve port 10b, the fluid flow and thus the pressure reduction at the high-pressure port 2 via the first hydraulic path can be slowed down in the second state. This improves the controllability of the pressure reduction at the high-pressure port 2 during the second state. Furthermore, the efficiency of pressure build-up is increased, since the fluid from the first pump port 6a to the high-pressure port 2 can also flow via the second hydraulic path without having to pass through a throttle.
[0047] Fig. 5 Figure 1 shows a schematic representation of a hydraulic circuit according to a fifth embodiment of the invention. The fifth embodiment from Fig. 5 is based on similar features to the fourth embodiment from Fig. 4 .
[0048] Furthermore, the check valve system 8 includes a third check valve 13. The third check valve 13 is fluidically connected to the second valve port 8b at a fifth check valve port 13a and to the second check valve port 10b at a sixth check valve port 13b. The third check valve 13 is configured to prevent fluid flow from the fifth check valve port 13a to the sixth check valve port 13b and to allow fluid flow from the sixth check valve port 13b to the fifth check valve port 13a. The third check valve 13 is fluidically arranged parallel to the first throttle 11.
[0049] In the first state, a fluid flows through the first valve port 8a, the first check valve 10, and the second valve port 8b, increasing the pressure at the high-pressure port 2. This fluid flow, between the first check valve 10 and the second valve port 8b, passes partly through the third check valve 13 and partly through the first throttle 11. This arrangement presents less fluidic resistance to the fluid flow than if the entire fluid flow were to pass through the first throttle 11. This arrangement improved the efficiency of the check valve system 8. In the second state, the third check valve 13 prevents fluid flow from the fifth check valve port 13a to the sixth check valve port 13b. The entire fluid flow then flows from the high-pressure port 2, through the second valve port 8b, the first throttle 11, the first check valve 10, and the first valve port 8a.Since the entire fluid flow between the second valve port 8b and the first valve port 8a passes through the first throttle 11, this entire fluid flow is slowed down. This simplifies control of the pressure reduction at the high-pressure port. Thus, this embodiment allows for both efficient pressure build-up and improved control of the pressure reduction at the high-pressure port 2.
[0050] Fig. 6 Figure 1 shows a schematic representation of a hydraulic circuit according to a sixth embodiment of the invention. The sixth embodiment from Fig. 6 is based on similar features to the second embodiment from Fig. 2 and / or the third embodiment from Fig. 3 on.
[0051] The check valve system 8 comprises a second throttle 15, a fourth check valve 14, and a fifth check valve 16. The second throttle 15, the fourth check valve 14, and the fifth check valve 16 are fluidically arranged between the first check valve 10 and the first valve port 8a. The fourth check valve 14 is fluidically connected to the first check valve port 10a at a seventh check valve port 14b and to the first valve port 8a at an eighth check valve port 14a. The fourth check valve 14 is configured to prevent fluid flow from the seventh check valve port 14b to the eighth check valve port 14a and to allow fluid flow from the eighth check valve port 14a to the seventh check valve port 14b.
[0052] The fifth check valve 16 is arranged antiparallel to the fourth check valve 14. The fifth check valve 16 is fluidically connected to the first check valve port 10a at a ninth check valve port 16a and to the first valve port 8a at a tenth check valve port 16b. The fifth check valve 16 is configured to prevent fluid flow from the tenth check valve port 16b to the ninth check valve port 16a and to allow fluid flow from the ninth check valve port 16a to the tenth check valve port 16b. The second throttle 15 is fluidically arranged between the tenth check valve port 16b and the second valve port 8b and parallel to the fourth check valve 14.
[0053] In the first state, the fluid flows from the first pump port 6a, through the fourth check valve 14 and the first check valve 10, to the high-pressure port 2, and the pressure at the high-pressure port 2 increases. The positioning of the fifth check valve 16 prevents fluid flow through it and thus through the second throttle 15 in the first state. This allows for high efficiency in the first state, as no losses occur through the second throttle 15. In the second state, the fluid flows from the high-pressure port 2 to the first valve port 8a, through the fifth check valve 16 and the second throttle 15. The fourth check valve 14 blocks the fluid flow in the second state, and all fluid flows through the fifth check valve 16 and the second throttle 15. The second throttle 15 slows the fluid flow, making it easier to control the fluid flow in the second state.Thus, in the first state, this embodiment allows for an efficient pressure increase at the high-pressure port 2, and in the second state, an easily controlled pressure reduction at the high-pressure port 2.
[0054] Fig. 7 Figure 1 shows a schematic representation of a hydraulic circuit according to a seventh embodiment of the invention.
[0055] The seventh embodiment from Fig. 7 is based on similar features to the first embodiment from Fig. 1 .
[0056] Furthermore, the check valve system 8 comprises a first check valve 10, a fourth valve port 8e, a sixth check valve 18 that can be unlocked, and a third throttle 17. The first check valve 10 is connected to the first valve port 8a at a first check valve port 10a and to the second valve port 8b at a second check valve port 10b. The first check valve 10 is configured to prevent fluid flow from the second check valve port 10b to the first check valve port 10a and to allow fluid flow from the first check valve port 10a to the second check valve port 10b.
[0057] The fourth valve port 8e is fluidically connected to the low-pressure port 3. The sixth check valve 18 is fluidically connected to the fourth valve port 8e via an eleventh check valve port 18a and to the second valve port 8b via a twelfth check valve port 18b. The sixth check valve 18 is configured to prevent fluid flow from the twelfth check valve port 18b to the eleventh check valve port 18a and to allow fluid flow from the eleventh check valve port 18a to the twelfth check valve port 18b. The sixth check valve 18 has a second check valve control port 18c, through which fluid flow from the twelfth check valve port 18b to the eleventh check valve port 18a can be allowed. The second check valve control port 18c is fluidically connected to the control port 8c.
[0058] In the first state, the fluid flows through the first valve port 8a and the second valve port 8b, through the first check valve, to the high-pressure port 2, increasing the pressure at the high-pressure port 2. No fluid flows through the third throttle 17 or any other throttle in this state. In the second state, the first check valve 10 prevents fluid flow from the second valve port 8b to the first valve port 8a. The fluid flows from the first pump outlet 6a through the control port 8c to the second check valve control port 18c. This allows the sixth check valve 18 to permit fluid flow from the high-pressure port 2 through the second valve port 8b and the fourth valve port 8e to the low-pressure port 3, thereby reducing the pressure. In this state, the fluid flows through the third throttle 17 and is slowed down.This improves the controllability of the pressure reduction at the high-pressure port 2, without affecting the efficiency of pressure build-up at the high-pressure port 2.
[0059] Fig. 8 Figure 1 shows a schematic representation of a hydraulic circuit according to an eighth embodiment of the invention.
[0060] The eighth embodiment from Fig. 8 is based on similar features to the first embodiment from Fig. 1 .
[0061] Furthermore, the check valve system 8 includes a first check valve 10. The first check valve is connected to the first valve port 8a at a first check valve port 10a and to the second valve port 8b at a second check valve port 10b. The first check valve 10 is configured to prevent fluid flow from the second check valve port 10b to the first check valve port 10a and to allow fluid flow from the first check valve port 10a to the second check valve port 10b. This allows for efficient pressure build-up at the high-pressure port 2 in the first state, since no further hydraulic elements are arranged between the first valve port 8a and the second valve port 8b that would present hydraulic resistance.
[0062] The check valve system 8 has a fourth valve port 8e, a sixth check valve 18 that can be unlocked, and a third throttle 17. The fourth valve port 8e is fluidically connected to the low-pressure port 3. The sixth check valve 18 is fluidically connected to the fourth valve port 8e via an eleventh check valve port 18a and to the second valve port 8b via a twelfth check valve port 18b. The sixth check valve 18 is configured to prevent fluid flow from the twelfth check valve port 18b to the eleventh check valve port 18a and to allow fluid flow from the eleventh check valve port 18a to the twelfth check valve port 18b. The sixth check valve 18 has a second check valve control port 18c through which fluid flow from the twelfth check valve port 18b to the eleventh check valve port 18a can be enabled.The second check valve control port 18c is fluidically connected to the control port 8c.
[0063] In the first state, the fluid flows through the first valve port 8a, the first check valve 10, and the second valve port 8b to the high-pressure port 2, increasing the pressure at the high-pressure port 2. No fluid flows through the third restrictor 17 in this state. In the second state, the first check valve 10 prevents fluid flow from the second valve port 8b to the first valve port 8a. Fluid flows from the first pump outlet 6a via the control port 8c to the second check valve control port 18c. This allows the sixth check valve 18 to allow fluid flow from the high-pressure port 2 via the second valve port 8b and the fourth valve port 8e to the low-pressure port 3, thereby reducing the pressure. In this state, the fluid also flows through the third restrictor 17 and is slowed down.This improves the controllability of the pressure reduction at the high-pressure port 2, without affecting the efficiency of pressure build-up at the high-pressure port 2.
[0064] Fig. 9 shows a schematic representation of a hydraulic circuit according to a ninth embodiment of the invention.
[0065] The ninth embodiment from Fig. 9 presents an alternative embodiment of the eighth embodiment Fig. 8 The ninth embodiment features an alternative configuration of the feed unit 4. Instead of the seventh check valve 20 and the eighth check valve 21, the feed unit 4 in the ninth embodiment is designed as a dual-pressure valve 22. This reduces the number of components required in the hydraulic circuit 1 and allows for a more compact design of the hydraulic circuit 1.
[0066] In addition to the foregoing written description of the invention, explicit reference is hereby made to the graphic representation of the invention in the following for its supplementary disclosure. Fig. 1 bis 8 Reference made to. Bezugszeichenliste
[0067] 1 Hydraulic circuit 2 High-pressure connection 3 Low-pressure connection 4 Feed unit 5 Pump system 6 Pump 6a First pump connection 6b Second pump connection 7 Shaft 8 Check valve system 8a First valve connection 8b Second valve connection 8c Control connection 8d Third valve connection 8b Fourth valve connection 9 Pressure equalization line 10 First check valve 10a First check valve connection 10b Second check valve connection 10c First check valve control connection 10d Displacement 10e Piston 10f Check element 11 First throttle 12 Second check valve 12a Third check valve connection 12b Fourth check valve connection 13 Third check valve 13a Fifth check valve connection 13b Sixth check valve connection 14 Fourth check valve 14a Eighth check valve connection 14b Seventh check valve connection 15 Second throttle 16 Fifth check valve 16 Lower check valve connection 16 Tenth check valve connection 17 Third throttle 18 Sixth check valve18a eleventh check valve connection 18b twelfth check valve connection 18c second check valve control connection 19 pressure relief valve 19a first pressure relief valve connection 19b second pressure relief valve connection 20 seventh check valve 20a thirteenth check valve connection 20b fourteenth check valve connection 21 eighth check valve 21a fifteenth check valve connection 21b sixteenth check valve connection 22 dual pressure valve
Claims
1. Hydraulic circuit (1) comprising • a high-pressure port (2), • a low-pressure port (3), • a feed unit (4), and • a pumping system (5), • wherein the low-pressure port (3) is fluidically connected to the high-pressure port (2) by means of a series connection of the feed unit (4) and the pumping system (5), • wherein the pumping system (5) comprises a pump (6) for delivering a fluid, a shaft (7) for driving the pump (6) and at least one pilot-operated check valve system (8), • wherein the pump (6) is configured to deliver the fluid from a first pump port (6a) to a second pump port (6b) in a first state and to deliver the fluid from the second pump port (6b) to the first pump port (6a) in a second state, • wherein the check valve system (8) is fluidically connected to the second pump port (6b) at a first valve port (8a) and to the high-pressure port (2) at a second valve port (8b), • wherein the check valve system (8) is designed to prevent a fluid flow from the second valve port (8b) to the first valve port (8a) and to allow a fluid flow from the first valve port (8a) to the second valve port (8b), • wherein the check valve system (8) comprises a control port (8c), which can be used to release a fluid flow from the second valve port (8b) to the first valve port (8a), • wherein the hydraulic circuit (1) is designed to release the fluid flow from the second valve port (8b) to the first valve port (8a) via the control port (8c) when the pump (6) is in the second state, • wherein, when the pump (6) is in a first state, the feed unit (4) is configured to enable a fluid flow from the low-pressure port (3) to the first pump port (6a) and to prevent a fluid flow from the second pump port (6b) to the low-pressure port (3), • wherein, when the pump (6) is in a second state, the feed unit (4) is configured to enable a fluid flow from the low-pressure port (3) to the second pump port (6b) and to prevent a fluid flow from the first pump port (6a) to the low-pressure port (3), • wherein, • the pump (6) has a leakage flow towards the shaft (7) when delivering the fluid, and the shaft (7) is connected to the low-pressure port (3) by means of a pressure equalization line (9) in order to drain the fluid from the shaft (7), and / or • the check valve system (8) comprises a leakage flow between the control port (8c) and the first valve port (8a) when the pump (6) is in the second state.
2. Hydraulic circuit (1) according to Claim 1, characterized in that the check valve system (8) comprises at least a first check valve (10), • wherein the first check valve (10) is connected to the first valve port (8a) at a first check valve port (10a) and to the second valve port (8b) at a second check valve port (10b), and • wherein the first check valve (10) is designed to prevent a fluid flow from the second check valve port (10b) to the first check valve port (10a) and to allow a fluid flow from the first check valve port (10a) to the second check valve port (10b).
3. Hydraulic circuit (1) according to Claim 2, characterized in that the first check valve (10) is designed to be pilot-operated, • wherein the first check valve (10) comprises a first check valve control port (10c), which can be used to release a fluid flow from the second check valve port (10b) to the first check valve port (10a), and • wherein the first check valve control port (10c) is fluidically connected to the control port (8c).
4. Hydraulic circuit (1) according to either of Claims 2 and 3, characterized in that the check valve (10) comprises a displacement volume (10d), a piston (10e) and a check valve element (10f), • wherein, when the check valve element (10f) is in a third state, the check valve element (10f) is configured to prevent a fluid flow from the second check valve port (10b) to the first check valve port (10a), • wherein, when the check valve element (10f) is in a fourth state, the check valve element (10f) is configured to release a fluid flow from the second check valve port (10b) to the first check valve port (10a), • wherein, in the event of pressure build-up in the displacement volume (10d) via the control port (8c), the piston (10e) is configured to move in a first direction and to place the check valve element (10f) into the fourth state, and • wherein the check valve (10) comprises a leakage flow between the check valve control port (10c) and the first check valve port (10a) via the displacement volume (10d).
5. Hydraulic circuit (1) according to any of the preceding claims, characterized in that the check valve system (8) comprises at least a first throttle (11), • wherein the first throttle (11) is arranged between the first valve port (8a) and the second valve port (8b), and • wherein the first check valve (10) and the first throttle (11) are fluidically connected to one another in series.
6. Hydraulic circuit (1) according to either of preceding Claims 2 and 4, characterized in that the check valve system (8) comprises at least a second check valve (12) and a third valve port (8d), • wherein the third valve port (8d) is fluidically connected to the second pump port (6b), • wherein the second check valve (12) is connected to the third valve port (8d) at a third check valve port (12a) and to the second valve port (8b) at a fourth check valve port (12b), and • wherein the second check valve (12) is designed to prevent a fluid flow from the fourth check valve port (12b) to the third check valve port (12a) and to allow a fluid flow from the third check valve port (12a) to the fourth check valve port (12b).
7. Hydraulic circuit (1) according to Claims 5 and 6, characterized in that the check valve system (8) comprises a third check valve (13), • wherein the third check valve (13) is fluidically connected to the second valve port (8b) by means of a fifth check valve port (13a) and is fluidically connected to the second check valve port (10b) by means of a sixth check valve port (13b), • wherein the third check valve (13) is designed to prevent a fluid flow from the fifth check valve port (13a) to the sixth check valve port (13b) and to allow a fluid flow from the sixth check valve port (13b) to the fifth check valve port (13a), and • wherein the third check valve (13) is arranged fluidically parallel to the first throttle (11).
8. Hydraulic circuit (1) according to Claims 3 to 7, characterized in that the check valve system (8) comprises a second throttle (15), a fourth check valve (14) and a fifth check valve (16), • wherein the second throttle (15), the fourth check valve (14) and the fifth check valve (16) are arranged fluidically between the first check valve (10) and the first valve port (8a), • wherein the fourth check valve (14) is fluidically connected to the first check valve port (10a) at a seventh check valve port (14b) and to the first valve port (8a) at an eighth check valve port (14a), • wherein the fourth check valve (14) is designed to prevent a fluid flow from the seventh check valve port (14b) to the eighth check valve port (14a) and to allow a fluid flow from the eighth check valve port (14a) to the seventh check valve port (14b), • wherein the fifth check valve (16) is arranged antiparallel to the fourth check valve (14), • wherein the fifth check valve (16) is fluidically connected to the first check valve port (10a) at a ninth check valve port (16a) and to the first valve port (8a) at a tenth check valve port (16b), • wherein the fifth check valve (16) is designed to prevent a fluid flow from the tenth check valve port (16b) to the ninth check valve port (16a) and to allow a fluid flow from the ninth check valve port (16a) to the tenth check valve port (16b), and • wherein the second throttle (15) is arranged fluidically between the tenth check valve port (16b) and the second valve port (8b) and parallel to the fourth check valve (14).
9. Hydraulic circuit (1) according to Claim 2, characterized in that the check valve system (8) comprises a fourth valve port (8e), a pilot-operated sixth check valve (18) and comprises a third throttle (17), • wherein the fourth valve port (8e) is fluidically connected to the low-pressure port (3), • wherein the sixth check valve (18) is fluidically connected to the fourth valve port (8e) by means of an eleventh check valve port (18a) and to the second valve port (8b) by means of a twelfth check valve port (18b), and • wherein the sixth check valve (18) is designed to prevent a fluid flow from the twelfth check valve port (18b) to the eleventh check valve port (18a) and to allow a fluid flow from the eleventh check valve port (18a) to the twelfth check valve port (18b), • wherein the sixth check valve (18) comprises a second check valve control port (18c), which can be used to release a fluid flow from the twelfth check valve port (18b) to the eleventh check valve port (18a), and • wherein the second check valve control port (18c) is fluidically connected to the control port (8c).
10. Hydraulic circuit (1) according to any of the preceding claims, characterized by a pressure-limiting valve (19), wherein the pressure-limiting valve (19) is connected to the high-pressure port (2) at a first pressure-limiting valve port (19a) and is connected to the low-pressure port (3) at a second pressure-limiting valve port (19b), wherein the pressure-limiting valve (19) is connected to the high-pressure port (2) and the low-pressure port (3) parallel to the pumping system (5) and to the feed unit.
11. Hydraulic circuit (1) according to any of the preceding claims, characterized in that the feed unit comprises a seventh check valve (20) and an eighth check valve, • wherein the seventh check valve (20) is connected to the low-pressure port (3) at a thirteenth check valve port (20a) and connected to the first pump port (6a) at a fourteenth check valve port (20b), • wherein the seventh check valve (20) is designed to prevent a fluid flow from the fourteenth check valve port (20b) to the thirteenth check valve port (20a) and to allow a fluid flow from the thirteenth check valve port (20a) to the fourteenth check valve port (20b), • wherein the eighth check valve (21) is connected to the low-pressure port (3) at a fifteenth check valve port (16b) and connected to the second pump port (6b) at a sixteenth check valve port (16b), • wherein the eighth check valve (21) is designed to prevent a fluid flow from the sixteenth check valve port (16b) to the fifteenth check valve port (16b) and to allow a fluid flow from the fifteenth check valve port (16b) to the sixteenth check valve port (16b).
12. Hydraulic circuit (1) according to any of the preceding claims, characterized in that the feed unit (4) is in the form of a two-pressure valve (22).