Hydraulic control system with energy recovery

Abstract

This utility model discloses a hydraulic control system with energy recovery, including an oil supply unit and a left lifting cylinder and a right lifting cylinder connected to the oil supply unit; the oil supply pipeline includes a center variable displacement piston pump, a working pump, and a motor for driving the center variable displacement piston pump and the working pump. The oil inlet end of the center variable displacement piston pump and the working pump is connected to a hydraulic oil tank, and the oil outlet end of the center variable displacement piston pump and the working pump is connected to the rodless chamber of the left lifting cylinder and the right lifting cylinder through a pipeline. This application sets the center variable displacement piston pump as the oil supply pump of the hydraulic system. Since the center variable displacement piston pump allows it to cross the zero point and enter the negative angle region, when the swashplate is at a negative angle, the pump's oil inlet and outlet are interchanged, and the pump's output flow direction is reversed. The center variable displacement piston pump is converted from a pump into a motor, which can then drive the motor to generate electricity, thereby realizing energy recovery.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic control system technology, specifically a hydraulic control system with energy recovery. Background Technology

[0002] Modern forklifts and stackers are often equipped with energy recovery systems. This means that when the forks of a forklift or stacker are lowered, high-pressure hydraulic oil drives the hydraulic motor to rotate, which in turn drives the power generation equipment to generate electricity, thus achieving energy recovery.

[0003] This energy recovery method often requires a drive unit and an energy recovery unit, resulting in a complex overall structure and high equipment costs. In addition, existing lifting hydraulic systems often use dual motors to drive the lifting cylinders and auxiliary actuators, further increasing the complexity and cost of the equipment. Utility Model Content

[0004] The purpose of this invention is to provide a hydraulic control system with energy recovery to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] A hydraulic control system with energy recovery includes an oil supply unit and a left lifting cylinder and a right lifting cylinder connected to the oil supply unit.

[0007] The oil supply pipeline includes a center variable displacement piston pump, a working pump, and a motor for driving the center variable displacement piston pump and the working pump. The oil inlet of the center variable displacement piston pump and the working pump is connected to a hydraulic oil tank. The oil outlet of the center variable displacement piston pump and the working pump is connected to the rodless chamber of the left lifting cylinder and the right lifting cylinder through a pipeline. A first check valve is provided on the pipeline connecting the working pump and the left lifting cylinder and the right lifting cylinder.

[0008] As a further embodiment of this utility model: the motor drive is connected to a triple pump, the triple pump including a center-variable piston pump, a gear pump and a working pump, the oil inlet of the gear pump is connected to the hydraulic oil tank through a second filter, and the oil outlet of the gear pump is connected to the S port of the center-variable piston pump through a first pressure reducing valve.

[0009] As a further embodiment of this utility model: the oil inlet of the over-center variable piston pump is connected to the hydraulic oil tank through a first filter.

[0010] As a further embodiment of this invention, a pressure sensor is provided at the oil outlet of the over-center variable displacement piston pump.

[0011] As a further embodiment of this utility model: the oil inlet end of the left lifting cylinder is connected to a left lifting valve block, the oil inlet end of the right lifting cylinder is connected to a right lifting valve block, the central variable piston pump is connected to the oil inlet ends of the left and right lifting valve blocks through a high-pressure filter, and the working pump is connected to the oil inlet ends of the left and right lifting valve blocks through a multi-way valve.

[0012] As a further embodiment of this utility model: the left lifting valve block and the right lifting valve block have the same structure. The right lifting valve block includes a main valve. The oil inlet end of the main valve is connected to the central variable piston pump and the working pump. The oil outlet end of the main valve is connected to the rodless chamber of the right lifting cylinder. The main valve is connected in parallel with a second check valve. The flow direction of the second check valve is from the connection end between the main valve and the right lifting cylinder to the other end of the main valve.

[0013] As a further embodiment of this utility model: the right lifting valve block is provided with an overflow valve, one end of which is connected to the rodless chamber of the right lifting cylinder, and the other end is connected to the oil return line of the rod chamber of the right lifting cylinder. The right lifting valve block is provided with an emergency lowering solenoid valve, which is arranged in parallel with the overflow valve.

[0014] As a further embodiment of this utility model: the bypass of the multi-way valve is connected to a pilot control valve via a pipeline. The pilot control valve includes a two-position two-way solenoid valve that is connected to the multi-way valve. The oil outlet of the two-position two-way solenoid valve is connected to a second pressure reducing valve. The oil outlet of the second pressure reducing valve is connected to a two-position three-way solenoid valve. The oil outlet of the two-position three-way solenoid valve is connected to the main valve to push the valve core of the main valve to move.

[0015] As a further embodiment of this utility model: the oil inlet of the two-position two-way solenoid valve is connected to an accumulator, and the accumulator and the oil inlet of the two-position two-way solenoid valve are connected to the multi-way valve through a third one-way valve.

[0016] Compared with the prior art, the beneficial effects of this utility model are:

[0017] 1. This application sets a central variable displacement piston pump as the oil supply pump of the hydraulic system. Since the central variable displacement piston pump allows it to cross the zero point and enter the negative angle region, when the swashplate is at a negative angle, the pump's suction port and pressure port are interchanged, and the pump's output flow direction is reversed. The central variable displacement piston pump is converted from a pump into a motor, which can then drive the motor to generate electricity. The drive motor and oil supply pump of this application can both supply oil and generate electricity, thereby realizing energy recovery.

[0018] 2. By setting up a triple pump, this application further simplifies the number of equipment, making the equipment simple and the cost lower;

[0019] 3. This application sets a central variable displacement piston pump and a working pump as the main pump and auxiliary pump, and the main pump and auxiliary pump are connected in series and driven by a motor. When the gantry is lifted, the two pumps combine to provide sufficient flow to meet the lifting speed requirements of the gantry. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the hydraulic system in this embodiment;

[0021] Figure 2 This is a schematic diagram of the center-shifting variable displacement piston pump system in this embodiment;

[0022] Figure 3 This is a schematic diagram of the first pressure reducing valve system in this embodiment;

[0023] Figure 4 This is a schematic diagram of the pilot control valve system in this embodiment;

[0024] Figure 5 This is a schematic diagram of the left lifting valve block system in this embodiment;

[0025] Figure 6 This is a schematic diagram of the right lifting valve block system in this embodiment;

[0026] Figure 7 This is a schematic diagram of the multi-way valve system in this embodiment;

[0027] In the diagram: 1-Hydraulic oil tank, 2-Motor, 3-First filter, 4-Triple pump, 5-First pressure reducing valve, 6-Second filter, 7-Third filter, 8-Pressure sensor, 9-High pressure filter, 10-Left lifting cylinder, 11-Right lifting cylinder, 12-Left lifting valve block, 13-Right lifting valve block, 14-Pilot control valve, 15-Accumulator, 16-First check valve, 17-Multi-way valve, 41-Center variable displacement piston pump, 42-Gear pump, 43-Working pump, 121-Emergency descent solenoid valve, 131-Main valve, 132-Second check valve, 133-Relief valve, 134-Emergency descent solenoid valve, 141-Second pressure reducing valve, 142-Two-position three-way solenoid valve, 143-Two-position two-way solenoid valve, 144-Third check valve. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0029] like Figure 1-2As shown in the embodiment of this utility model, a hydraulic control system with energy recovery includes an oil supply unit and a left lifting cylinder 10 and a right lifting cylinder 11 connected to the oil supply unit.

[0030] The oil supply line includes a triple pump 4, which includes a center variable displacement piston pump 41, a gear pump 42, a working pump 43, and a motor 2 for driving the center variable displacement piston pump 41, gear pump 42, and working pump 43. The oil inlet of the center variable displacement piston pump 41 is connected to the hydraulic oil tank 1 through a first filter 3. A pressure sensor 8 is installed at the oil outlet of the center variable displacement piston pump 41. The oil inlets of the center variable displacement piston pump 41 and the working pump 43 are connected to the hydraulic oil tank 1. The oil inlet of the gear pump 42 is connected to the hydraulic oil tank 1 through a second filter 6. The oil outlet of the gear pump 42 is connected to the S port of the center variable displacement piston pump 41 through a first pressure reducing valve 5.

[0031] like Figure 3-6 As shown, the oil outlets of the center variable displacement piston pump 41 and the working pump 43 are connected to the rodless chambers of the left lifting cylinder 10 and the right lifting cylinder 11 via pipelines. A first check valve 16 is provided on the pipeline connecting the working pump 43 to the left lifting cylinder 10 and the right lifting cylinder 11. In this embodiment, the oil inlet of the left lifting cylinder 10 is connected to the left lifting valve block 12, and the oil inlet of the right lifting cylinder 11 is connected to the right lifting valve block 13. The center variable displacement piston pump 41 is connected to the oil inlet of the left lifting valve block 12 and the right lifting valve block 13 via a high-pressure filter 9. The working pump 43 is connected to the oil inlet of the left lifting valve block 12 and the right lifting valve block 13 via a multi-way valve 17. The left lifting valve block 12 and the right lifting valve block 13 have the same structure. The right lifting valve block 13 includes a main valve 313. The oil inlet of the main valve 131 is connected to the central variable displacement piston pump 41 and the working pump 43. The oil outlet of the main valve 131 is connected to the rodless chamber of the right lifting cylinder 11. A second check valve 132 is connected in parallel with the main valve 131. The flow direction of the second check valve 132 is from the connection end of the main valve 131 and the right lifting cylinder 11 to the other end of the main valve 131. An overflow valve 133 is provided in the right lifting valve block 13. One end of the overflow valve 133 is connected to the rodless chamber of the right lifting cylinder 11, and the other end is connected to the return oil line of the rod chamber of the right lifting cylinder 11. An emergency descent solenoid valve 134 is provided in the right lifting valve block 13. The emergency descent solenoid valve 134 is arranged in parallel with the overflow valve 133.

[0032] like Figure 7As shown, the bypass of the multi-way valve 17 is connected to the pilot control valve 14 via a pipeline. The pilot control valve 14 includes a two-position two-way solenoid valve 143 connected to the multi-way valve 17. The oil outlet of the two-position two-way solenoid valve 143 is connected to a second pressure reducing valve 141. The oil outlet of the second pressure reducing valve 141 is connected to a two-position three-way solenoid valve 142. The oil outlet of the two-position three-way solenoid valve 142 is connected to the main valve 131 to push the valve core of the main valve 131 to move. The oil inlet of the two-position two-way solenoid valve 143 is connected to an accumulator 15. The accumulator 15 and the oil inlet of the two-position two-way solenoid valve 143 are connected to the multi-way valve 17 via a third check valve 144.

[0033] In this embodiment, during use, motor 2 drives the triple pump 4 to rotate. The transverse variable piston pump 41 in the triple pump 4 draws oil from the hydraulic oil tank 1 through the suction filter element. The outlet A of the transverse variable piston pump 41 is connected to the high-pressure filter 9, which in turn connects to the P5 port of the left lifting valve block 12 and the P6 port of the right lifting valve block 13. Gear pump 42 draws oil from the hydraulic oil tank 1 through the suction filter element. Its outlet is connected to the P1 port of the pressure reducing valve 5. The outlet A1 of the pressure reducing valve 5 is connected to the S port of the transverse variable piston pump 41. Working pump 43 draws oil from the hydraulic oil tank 1 through the suction filter element 7. The outlet of working pump 43 is connected to the P3 port of the multi-way valve 17. The outlet A3 of the multi-way valve 17 is connected to the P5 port of the left lifting valve block 12 and the P6 port of the right lifting valve block 13 through the first check valve 16. The P2 port of the multi-way valve 17 is connected to the P4 port of the pilot control valve 14. The X port of the pilot control valve 14 is connected to the X1 port of the left lifting valve block 12 and the X2 port of the right lifting valve block, respectively. The ACC port of the pilot control valve 14 is connected to the accumulator 15. The T4 port of the pilot control valve 14, together with the T5 port of the left lifting valve block 12, the T6 port of the right lifting valve block, and the T3 port of the multi-way valve, returns to the hydraulic oil tank 1.

[0034] When the gantry is raised normally, after the electric control handle is activated, motor 2 outputs its speed in real time. Motor 2 drives the triple pump 4 and the working gear pump 42 to draw oil from the hydraulic oil tank 1 through the second filter 6 and send it to the P1 port of the first pressure reducing valve 5. After pressure reduction, the hydraulic oil enters the servo oil supply port S of the center variable piston pump 41 through the A1 port of the first pressure reducing valve 5, controlling the piston movement of the center variable piston pump 41, thereby changing the tilt angle of the swashplate. The center variable piston pump 41 draws hydraulic oil from the oil tank 1, pressurizes it, and sends it to the left lifting valve block 12 and the right lifting valve block 13 through the high-pressure filter 9. The working pump 43 draws hydraulic oil from the oil tank 1, pressurizes it, and then merges it with the oil from the high-pressure filter 9 after passing through the multi-way valve 17 and the first check valve 16, sending it to the left lifting valve block 12 and the right lifting valve block 13. This ensures that the gantry has sufficient hydraulic fluid to drive the left lifting cylinder 10 and the right lifting cylinder 11 to lift synchronously. At this time, the two-position three-way solenoid valve 145 and the two-position two-way solenoid valve 143 of the pilot control valve 14 are not working. The hydraulic oil coming out from the A4 port of the multi-way valve enters the P4 port of the pilot control valve 14 and enters the accumulator 15 for filling through the third check valve 144. Hydraulic oil entering the right lifting valve block 13 passes through ports D1 and D2 of the main valve 131 and then through port A6 of the right lifting valve block 13 into the rodless chamber P7 of the right lifting cylinder 11. Simultaneously, excess oil passes through the second check valve 132 (G1-G2) in the right lifting valve block 13 and enters the A6 outlet of the right lifting valve block 13, thus entering the rodless chamber of the right lifting cylinder 11. Similarly, hydraulic oil entering the left lifting valve block 12 passes through ports K2 and K1 of the main valve 131 and then through port A5 of the left lifting valve block 12 into the rodless chamber P8 of the left lifting cylinder 10. Simultaneously, excess oil passes through the check valves (L1-L2) in the left lifting valve block 12 and enters the A5 outlet of the left lifting valve block 10, thus entering the rodless chamber of the left lifting cylinder 10.

[0035] High-pressure oil enters the rodless chambers of the left lifting cylinder 10 and the right lifting cylinder 11, pushing the piston rods inside the left lifting cylinder 10 and the right lifting cylinder 11 to move upward synchronously, thus pushing the gantry and container spreader to move upward simultaneously, thereby realizing the lifting movement of the container.

[0036] When the gantry is in the energy recovery state during descent under no-load or full-load conditions, after the electric control handle is activated, the oil from port A4 of the multi-way valve 17 enters port P4 of the pilot control valve 14. The two-position two-way solenoid valve 143 of the pilot control valve 14 is energized and N1 and N2 are connected. The hydraulic oil passes through the second pressure reducing valve 141. The main function of the second pressure reducing valve 141 is to reduce the pressure of the oil and protect the two-position three-way solenoid valve 142. The oil from the second pressure reducing valve 141 enters the two-position three-way solenoid valve 142, pushing the valve core to move to the right and connecting ports N3 and N4 of the two-position three-way solenoid valve 142. The hydraulic oil is then sent to port X of the pilot control valve, and the hydraulic oil enters port X1 of the left lifting valve block and port X2 of the right lifting valve block respectively. Hydraulic oil from the right lifting valve block X2 enters the main valve 131, pushing the valve core to the right and connecting the A6-D2-D1-P6 oil circuit. Similarly, the A5-K1-K2-P5 oil circuit of the left lifting valve block is connected. At this time, the rodless chambers of the left lifting cylinder 10 and the right lifting cylinder are filled with oil under a certain pressure, which is squeezed outward under the gravity of the gantry's descent. The squeezed-out hydraulic oil enters the A5 port of the left lifting valve block 12 through the P8 port of the left lifting cylinder 10, and the A6 port of the right lifting valve block 13 through the P7 port of the right lifting cylinder. After passing through the A6-D2-D1-P6 oil circuit and the A5-K1-K2-P5 oil circuit respectively, it enters the A port of the negative oscillating pump through the high-pressure filter 9. The high-pressure filter 9 is a two-way filter, primarily used to filter impurities in the heavy oil of the system. It also prevents damage to the central variable displacement piston pump 41. The swashplate of the central variable displacement piston pump 41 is adjusted to change its swashplate angle, thus achieving energy recovery. The central variable displacement piston pump 41 is allowed to cross zero and enter the negative angle region. When the swashplate is at a negative angle, the pump's suction and discharge ports are interchanged. The pump's output flow direction reverses, and the central variable displacement piston pump 41 transforms from a pump into a motor. When the load decreases, the load can conversely drive the pump, converting mechanical energy into hydraulic energy for energy recovery.

[0037] At the same time, the T8 port of the left lifting cylinder 10 and the T7 port of the right lifting cylinder 11 draw oil from the hydraulic oil tank 1 in the opposite direction to balance the negative pressure in the rod chamber of the left lifting cylinder 11 and the right lifting cylinder 11, and also to lubricate the piston rod.

[0038] When the system malfunctions or is in a shutdown state, the A4 port of the multi-way valve 17 cannot provide a stable oil supply. The pressurized oil stored in the accumulator 15 enters the two-position two-way solenoid valve 143, connecting N1 and N2. The hydraulic oil passes through the second pressure reducing valve 141, whose main function is to reduce the oil pressure and protect the two-position three-way solenoid valve 142. The oil from the second pressure reducing valve 141 enters the two-position three-way solenoid valve 142, pushing the valve core to the right and connecting the N3 and N4 ports of the two-position three-way solenoid valve 142. This sends the hydraulic oil to the X port of the pilot control valve, where it enters the X1 port of the left lifting valve block and the X2 port of the right lifting valve block. The hydraulic oil from the X2 port of the right lifting valve block enters the main valve 131, pushing the valve core to the right and connecting the A6-D2-D1-P6 oil circuit. Similarly, the A5-K1-K2-P5 oil circuit of the left lifting valve block is connected, enabling the gantry to descend. When the pressurized oil stored in the accumulator 15 is depleted, the back pressure at the one-way valve 144 decreases. After the vehicle starts normally, port A4 of the multi-way valve 17 continues to supply oil to the accumulator 15 for filling. This ensures that sufficient oil is supplied to the main valves of the left lifting valve block 12 and the right lifting valve block 13 to provide pilot opening oil.

[0039] Emergency descent solenoid valves 134 are installed in the lifting valve block 12 and the right lifting valve block 13. When the system fails and the gantry cannot descend, an emergency descent solenoid valve 134 can be energized by manually controlling a switch, which connects oil circuits A5-K5-K6-T5 and A6-D4-D6-T6 to achieve emergency descent of the gantry.

[0040] Pressure sensor 8 detects the pressure of the negative oscillating pump in real time, and the electronic control system uses the pressure signal to precisely control the pump's working status.

[0041] The vehicle switches between the two states in real time during operation to load the container. At the same time, when the container is descending, the energy of the fork descent is recovered by controlling the swing direction of the negative sway pump. The recovered electrical energy is then used to power the motor.

[0042] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0043] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A hydraulic control system with energy recovery, characterized in that, It includes an oil supply unit and a left lifting cylinder (10) and a right lifting cylinder (11) connected to the oil supply unit; The oil supply unit includes a center variable displacement piston pump (41), a working pump (43), and a motor (2) for driving the center variable displacement piston pump (41) and the working pump (43). The oil inlet of the center variable displacement piston pump (41) and the working pump (43) is connected to a hydraulic oil tank (1). The oil outlet of the center variable displacement piston pump (41) and the working pump (43) is connected to the rodless chamber of the left lifting cylinder (10) and the right lifting cylinder (11) through a pipeline. A first check valve (16) is provided on the pipeline connecting the working pump (43) to the left lifting cylinder (10) and the right lifting cylinder (11).

2. The hydraulic control system with energy recovery according to claim 1, characterized in that, The motor (2) drives a triple pump (4), which includes a center variable piston pump (41), a gear pump (42), and a working pump (43). The oil inlet of the gear pump (42) is connected to the hydraulic oil tank (1) through a second filter (6), and the oil outlet of the gear pump (42) is connected to the S port of the center variable piston pump (41) through a first pressure reducing valve (5).

3. The hydraulic control system with energy recovery according to claim 1, characterized in that, The inlet of the over-center variable displacement piston pump (41) is connected to the hydraulic oil tank (1) through the first filter (3).

4. The hydraulic control system with energy recovery according to claim 1, characterized in that, The outlet end of the over-center variable piston pump (41) is equipped with a pressure sensor (8).

5. The hydraulic control system with energy recovery according to claim 1, characterized in that, The left lifting cylinder (10) is connected to the left lifting valve block (12) at its inlet end, and the right lifting cylinder (11) is connected to the right lifting valve block (13) at its inlet end. The center variable piston pump (41) is connected to the inlet ends of the left lifting valve block (12) and the right lifting valve block (13) through a high-pressure filter (9). The working pump (43) is connected to the inlet ends of the left lifting valve block (12) and the right lifting valve block (13) through a multi-way valve (17).

6. The hydraulic control system with energy recovery according to claim 5, characterized in that, The left lifting valve block (12) and the right lifting valve block (13) have the same structure. The right lifting valve block (13) includes a main valve (131). The oil inlet of the main valve (131) is connected to the central variable piston pump (41) and the working pump (43). The oil outlet of the main valve (131) is connected to the rodless chamber of the right lifting cylinder (11). The main valve (131) is connected in parallel with a second check valve (132). The flow direction of the second check valve (132) is from the connection end of the main valve (131) and the right lifting cylinder (11) to the other end of the main valve (131).

7. The hydraulic control system with energy recovery according to claim 6, characterized in that, The right lifting valve block (13) is provided with an overflow valve (133). One end of the overflow valve (133) is connected to the rodless chamber of the right lifting cylinder (11), and the other end is connected to the return oil pipeline of the rod chamber of the right lifting cylinder (11). The right lifting valve block (13) is provided with an emergency lowering solenoid valve (134). The emergency lowering solenoid valve (134) and the overflow valve (133) are arranged in parallel.

8. The hydraulic control system with energy recovery according to claim 6, characterized in that, The bypass of the multi-way valve (17) is connected to a pilot control valve (14) via a pipeline. The pilot control valve (14) includes a two-position two-way solenoid valve (143) connected to the multi-way valve (17). The oil outlet of the two-position two-way solenoid valve (143) is connected to a second pressure reducing valve (141). The oil outlet of the second pressure reducing valve (141) is connected to a two-position three-way solenoid valve (142). The oil outlet of the two-position three-way solenoid valve (142) is connected to the main valve (131) to push the valve core of the main valve (131) to move.

9. The hydraulic control system with energy recovery according to claim 8, characterized in that, The oil inlet of the two-position two-way solenoid valve (143) is connected to an accumulator (15), and the oil inlet of the accumulator (15) and the two-position two-way solenoid valve (143) are connected to the multi-way valve (17) through a third check valve (144).

Images