A manual forklift energy recovery hydraulic system and manual forklift

Abstract

The application discloses a manual forklift energy recovery hydraulic system and a manual forklift. The manual forklift energy recovery hydraulic system comprises a hydraulic pump for providing hydraulic oil for a working oil cylinder, wherein the hydraulic pump is in driving connection with a hydraulic pump motor; a two-quadrant pump for providing hydraulic oil for the working oil cylinder or recovering the gravitational potential energy of the hydraulic oil through an integrated reversing valve, wherein the two-quadrant pump is in driving connection with a two-quadrant pump motor; an inlet P1 of the integrated reversing valve is connected with an outlet of the hydraulic pump, an inlet P2 of the integrated reversing valve is connected with an outlet of the two-quadrant pump, a working port A1 is connected with a large cavity of a lifting oil cylinder, a working port A2 is connected with a large cavity of a tilting oil cylinder, a working port B2 is connected with a small cavity of the tilting oil cylinder, a working port A3 is connected with a left cavity of a side shifting oil cylinder, a working port B3 is connected with a right cavity of the side shifting oil cylinder, a working port A4 is connected with a left cavity of a distance adjusting oil cylinder, and a working port B4 is connected with a right cavity of the distance adjusting oil cylinder. The application has the characteristics of high energy recovery efficiency, low technical cost, simple structure and suitability for mass production.

Description

Technical Field

[0001] This invention belongs to the field of engineering machinery technology, specifically relating to a manual forklift energy recovery hydraulic system and a manual forklift. Background Technology

[0002] The construction machinery industry is undergoing a structural transformation from "high consumption and low efficiency" to "green and efficient." As core handling equipment in logistics warehousing and manufacturing, the energy loss during the operation of forklifts has gradually become a key breakthrough for energy conservation and upgrading in the industry. Currently, mainstream forklifts generally adopt return oil throttling control technology during the descent phase of picking up goods to ensure operational stability and driving comfort. This technology adjusts the descent speed through the pressure loss of the hydraulic valve throttling orifice. However, this traditional solution directly converts the gravitational potential energy of the goods into the heat energy of the hydraulic oil, resulting in a waste of 30%-50% of the energy. Furthermore, it requires additional investment in a cooling system to balance the oil temperature, creating a dual energy burden of "energy consumption and heat dissipation," which is seriously contrary to the development trend of green construction machinery.

[0003] To address this industry pain point, researchers have explored multi-dimensional technological improvement routes centered on the core goal of "gravitational potential energy recovery and reuse," ranging from hydraulic system optimization to the integration of new energy technologies. However, existing improvement solutions still have certain gaps for industrial application. For example, some existing technologies use energy accumulators to achieve energy recovery, but the energy recovery effect of energy accumulators is limited, and their large size makes them inconvenient to install and use. Some existing technologies adopt a "battery-motor-pump motor" architecture, and additionally configure high-precision controllers, dedicated solenoid valves, and multiple sets of status sensors and other electronic components, which not only significantly increases the hardware procurement cost of the system, but also increases the complexity of later debugging and maintenance, resulting in high overall production costs and making it difficult to adapt to the needs of mass production. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a manual forklift energy recovery hydraulic system and a manual forklift, which features high energy recovery efficiency, low technical cost, simple structure, and suitability for mass production.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, a manual forklift energy recovery hydraulic system is provided, comprising: a hydraulic pump for supplying hydraulic oil to a working cylinder, the hydraulic pump being driven by a hydraulic pump motor; a two-quadrant pump for supplying hydraulic oil to the working cylinder or recovering the gravitational potential energy of the hydraulic oil through an integrated directional valve, the two-quadrant pump being driven by a two-quadrant pump motor; the integrated directional valve having an inlet P1 connected to the outlet of the hydraulic pump, an inlet P2 connected to the outlet of the two-quadrant pump, a working port A1 connected to the large chamber of the lifting cylinder, a working port A2 connected to the large chamber of the tilting cylinder, a working port B2 connected to the small chamber of the tilting cylinder, a working port A3 connected to the left chamber of the side-shifting cylinder, a working port B3 connected to the right chamber of the side-shifting cylinder, a working port A4 connected to the left chamber of the adjusting cylinder, and a working port B4 connected to the right chamber of the adjusting cylinder.

[0006] Further, the integrated directional control valve includes: a pilot pressure reducing valve, the inlet of which is connected to the inlet P2 of the integrated directional control valve, and the outlet of which is connected to the inlet of a throttle orifice; the outlet of the throttle orifice is respectively connected to the control end of directional control valve one, the control end of directional control valve two, the inlet of the lifting pilot directional control valve, and the inlet of the tilting pilot directional control valve; the outlet of the tilting pilot directional control valve is connected to the inlet of the side shift pilot directional control valve, the outlet of the side shift pilot directional control valve is connected to the inlet of the adjusting pitch pilot directional control valve, and the outlets of the adjusting pitch pilot directional control valve and the lifting pilot directional control valve are connected to the oil tank; the inlet of directional control valve one is connected to the inlet P2 of the integrated directional control valve, and the outlet of directional control valve one is respectively connected to the inlet two of the tilting directional control valve, the inlet two of the side shift directional control valve, and the inlet two of the adjusting pitch directional control valve; the inlet of directional control valve two is connected to the inlet P1 of the integrated directional control valve, and the outlet of directional control valve two is respectively connected to the inlet one and the inlet three of the lifting directional control valve.

[0007] Furthermore, the inlet 2 of the lifting directional valve is connected to the inlet P1 of the integrated directional valve; the outlets 1 and 2 of the lifting directional valve are respectively connected to the inlet 1 of the tilt directional valve; and the outlet 3 of the lifting directional valve is connected to the working port A1. The inlet 2 of the tilt directional valve is respectively connected to the inlet P1 and inlet P2 of the integrated directional valve; the inlet 3 is connected to the working port B2; the outlet 1 is connected to the inlet 1 of the side shift directional valve; the outlet 2 is connected to the working port A2; and the outlet 3 is connected to the oil tank. The inlet 2 of the side shift directional valve is respectively connected to the inlet P1 and inlet P2 of the integrated directional valve; the inlet 3 is connected to the working port B3; the outlet 1 is connected to the inlet 1 of the adjustable pitch directional valve; the outlet 2 is connected to the working port A3; and the outlet 3 is connected to the oil tank. The inlet 2 of the adjustable pitch directional valve is respectively connected to the inlet P1 and inlet P2 of the integrated directional valve; the inlet 3 is connected to the working port B4; the outlet 1 is connected to the oil tank; the outlet 2 is connected to the working port A4; and the outlet 3 is connected to the oil tank.

[0008] Furthermore, when the lifting directional valve switches to the rising position, the lifting pilot directional valve is in the connected position. A portion of the hydraulic oil output from the two-quadrant pump enters the oil tank through the pilot pressure reducing valve, throttle orifice, and lifting pilot directional valve. The pilot pressure is zero, directional valve one is in the connected position, and directional valve two is in the one-way connected position. When the lifting directional valve operates alone, the hydraulic oil output from the hydraulic pump merges with the hydraulic oil output from the two-quadrant pump through directional valve two, and then enters the large chamber of the lifting cylinder through the lifting directional valve and working port A1, causing the lifting cylinder to extend. The lifting directional valve and the tilting... When at least one of the directional control valve, the side shift directional control valve, and the pitch control directional control valve operates in combination, a portion of the hydraulic oil output from the hydraulic pump merges with a portion of the hydraulic oil output from the second quadrant pump via the second directional control valve and then enters the large chamber of the lifting cylinder through the lifting directional control valve and working port A1, causing the lifting cylinder to extend. The other portion of the hydraulic oil output from the hydraulic pump and the other portion of the hydraulic oil output from the second quadrant pump merge through the first directional control valve and then enters the corresponding cylinder through at least one of the directional control valve, the side shift directional control valve, and the pitch control directional control valve, thus completing the corresponding action. Furthermore, when the lifting directional valve switches to the lowering position, and the tilt directional valve, side shift directional valve, and pitch directional valve are all inactive, the lifting pilot directional valve is in the shut-off position, and the tilt pilot directional valve, side shift pilot directional valve, and pitch directional valve are all in the connected position. A portion of the hydraulic oil in the large chamber of the lifting cylinder enters the oil tank through the pilot pressure reducing valve, throttle orifice, tilt pilot directional valve, side shift pilot directional valve, and pitch directional valve. The pilot pressure is zero, and directional valve one is in the connected position while directional valve two is in the one-way connected position. The remaining hydraulic oil in the large chamber of the lifting cylinder enters the second quadrant pump through the lifting directional valve and drives the second quadrant pump motor to generate electricity.

[0009] Furthermore, when the lifting directional valve switches to the lowering position, and at least one of the tilt directional valve, side shift directional valve, and pitch directional valve switches, the lifting pilot directional valve is in the cut-off position. At least one of the tilt pilot directional valve, side shift pilot directional valve, and pitch directional valve is in the cut-off position. A portion of the hydraulic oil in the large chamber of the lifting cylinder enters the control terminals of directional valve one and directional valve two through the pilot pressure reducing valve and the throttle orifice. Both directional valve one and directional valve two are in the cut-off position. The remaining hydraulic oil in the large chamber of the lifting cylinder enters the two-quadrant pump through the lifting directional valve and drives the two-quadrant pump motor to generate electricity.

[0010] Furthermore, the hydraulic pump is a gear pump.

[0011] Furthermore, the lifting directional valve and the lifting pilot directional valve switch in tandem, the tilt directional valve and the tilt pilot directional valve switch in tandem, the side shift directional valve and the side shift pilot directional valve switch in tandem, and the pitch directional valve and the pitch pilot directional valve switch in tandem.

[0012] Furthermore, it also includes a storage battery, which is electrically connected to the hydraulic pump motor and the two-quadrant pump motor respectively.

[0013] In a second aspect, a manual forklift is provided, the manual forklift being equipped with the manual forklift energy recovery hydraulic system described in the first aspect.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) This invention recovers the gravitational potential energy of the hydraulic oil in a manual forklift by using a hydraulic pump for supplying hydraulic oil to the working cylinder and a two-quadrant pump for supplying hydraulic oil to the working cylinder or recovering the gravitational potential energy of the hydraulic oil through an integrated directional valve; the hydraulic pump is driven by the hydraulic pump motor; the two-quadrant pump is driven by the two-quadrant pump motor; the inlet P1 of the integrated directional valve is connected to the outlet of the hydraulic pump, the inlet P2 is connected to the outlet of the two-quadrant pump, the working port A1 is connected to the large chamber of the lifting cylinder, the working port A2 is connected to the large chamber of the tilting cylinder, the working port B2 is connected to the small chamber of the tilting cylinder, the working port A3 is connected to the left chamber of the side-shifting cylinder, the working port B3 is connected to the right chamber of the side-shifting cylinder, the working port A4 is connected to the left chamber of the adjusting cylinder, and the working port B4 is connected to the right chamber of the adjusting cylinder; it significantly improves the system energy efficiency, achieves excellent energy-saving effect, and has the characteristics of high energy recovery efficiency, low technical cost, simple structure, and suitability for mass production; (2) The present invention can be improved based on the original hydraulic system architecture. Only the structure of some hydraulic main valves needs to be optimized to achieve the energy recovery and utilization function, which greatly reduces the system modification cost and application cost. (3) When realizing energy recovery and utilization, this invention does not require additional configuration of controllers, solenoid valves and other electrical control components and related electrical control systems, but adopts a pure hydraulic control scheme. This design not only effectively controls the production cost of the whole machine, but also avoids the possible failure risks of the electrical control system, and significantly improves the stability and long-term reliability of the hydraulic system. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the principle of a manual forklift energy recovery hydraulic system provided in an embodiment of the present invention; In the diagram: 1. Hydraulic pump motor; 2. Hydraulic pump; 3. Two-quadrant pump; 4. Two-quadrant pump motor; 5. Integrated directional valve; 6. Pilot pressure reducing valve; 7. Throttle orifice; 8. Directional valve one; 9. Directional valve two; 10. Lifting directional valve; 11. Tilting directional valve; 12. Side shift directional valve; 13. Adjustable pitch directional valve; 14. Lifting cylinder; 15. Tilting cylinder; 16. Side shift cylinder; 17. Adjustable pitch cylinder; 18. Oil tank; 19. Lifting pilot directional valve; 20. Tilting pilot directional valve; 21. Side shift pilot directional valve; 22. Adjustable pitch pilot directional valve. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0017] Example 1 like Figure 1 As shown, a manual forklift energy recovery hydraulic system includes: a hydraulic pump 2 for supplying hydraulic oil to the working cylinder and a two-quadrant pump 3 for supplying hydraulic oil to the working cylinder or recovering the gravitational potential energy of the hydraulic oil through an integrated directional valve 5. The hydraulic pump 2 is driven by a hydraulic pump motor 1, and the two-quadrant pump 3 is driven by a two-quadrant pump motor 4.

[0018] The inlet P1 of the integrated directional valve 5 is connected to the outlet of the hydraulic pump 2, the inlet P2 is connected to the outlet of the two-quadrant pump 3, the working port A1 is connected to the large chamber of the lifting cylinder 14, the working port A2 is connected to the large chamber of the tilting cylinder 15, the working port B2 is connected to the small chamber of the tilting cylinder 15, the working port A3 is connected to the left chamber of the side-shifting cylinder 16, the working port B3 is connected to the right chamber of the side-shifting cylinder 16, the working port A4 is connected to the left chamber of the adjusting cylinder 17, and the working port B4 is connected to the right chamber of the adjusting cylinder 17.

[0019] Power Unit: Hydraulic pump motor 1 serves as the basic power source, providing driving torque for the system. In this invention, hydraulic pump 2 is a gear pump, connected to hydraulic pump motor 1 via a coupling, receiving power from hydraulic pump motor 1 and outputting hydraulic oil to provide hydraulic power for the operation. Two-quadrant pump 3 has bidirectional working capability—it can output hydraulic oil when rotating forward to provide hydraulic power for the operation; when rotating in reverse, it can be driven by external hydraulic oil to rotate, thereby driving the associated motor to realize the power generation function. Two-quadrant pump motor 4 is connected to two-quadrant pump 3 via a coupling—it provides power to two-quadrant pump 3 when rotating forward, driving it to output hydraulic oil; when rotating in reverse, it realizes power generation under the drive of two-quadrant pump 3, and the generated electrical energy can be stored in the forklift's battery to complete energy recovery.

[0020] Control Unit: Integrated directional control valve 5, the core control component of the system, is used to control the on / off state of each oil circuit, the flow direction of hydraulic oil, and pressure regulation. It integrates the following key components: a pilot pressure reducing valve 6, used to regulate the system pressure to a stable pilot control pressure, providing a reliable pilot pressure source for the operation of each directional control valve; and a throttle orifice 7, used in conjunction with the pilot pressure reducing valve 6 to ensure stable flow in the pilot oil circuit and avoid pilot pressure fluctuations. In this invention, the throttle orifice 7 is a fixed throttle orifice. Directional control valves 8 and 9 are used to control the on / off switching of the return oil circuit of the large chamber of the lifting cylinder 14, enabling all hydraulic oil in the large chamber to flow back to the two-quadrant pump 3, driving the motor to generate electricity. In this invention, both directional control valves 8 and 9 are two-position two-way directional control valves. The lifting directional valve 10 controls the movement of the lifting cylinder 14; the tilt directional valve 11 controls the movement of the tilt cylinder 15; the side shift directional valve 12 controls the movement of the side shift cylinder 16; the pitch control directional valve 13 controls the movement of the pitch control cylinder 17, corresponding to the four core operating actions of the forklift; the lifting pilot directional valve 19 controls the pilot oil circuit of the lifting directional valve; the tilt pilot directional valve 20 controls the pilot oil circuit of the tilt directional valve; the side shift pilot directional valve 21 controls the pilot oil circuit of the side shift directional valve; and the pitch control pilot directional valve 22 controls the pilot oil circuit of the pitch control directional valve. The opening and closing of the pilot oil circuit controls the return direction of the large chamber of the lifting cylinder 14.

[0021] The inlet of the pilot pressure reducing valve 6 is connected to the inlet P2 of the integrated directional valve 5, and the outlet is connected to the inlet of the throttle orifice 7; the outlet of the throttle orifice 7 is connected to the control end of the directional valve 1, the control end of the directional valve 2, the inlet of the lifting pilot directional valve 19, and the inlet of the tilting pilot directional valve 20, respectively.

[0022] The outlet of the tilt pilot directional valve 20 is connected to the inlet of the lateral shift pilot directional valve 21, the outlet of the lateral shift pilot directional valve 21 is connected to the inlet of the pitch control pilot directional valve 22, and the outlet of the pitch control pilot directional valve 22 and the outlet of the lifting pilot directional valve 19 are connected to the oil tank 18 via the return port L of the integrated directional valve 5.

[0023] The inlet of directional valve 8 is connected to the inlet P2 of integrated directional valve 5, and the outlet of directional valve 8 is connected to the inlet II of tilt directional valve 11, the inlet II of side shift directional valve 12, and the inlet II of adjustable pitch directional valve 13, respectively.

[0024] The inlet of directional valve 29 is connected to the inlet P1 of integrated directional valve 5, and the outlet of directional valve 29 is connected to the inlet 1 and inlet 3 of lifting directional valve 10 respectively.

[0025] The inlet 2 of the lifting directional valve 10 is connected to the inlet P1 of the integrated directional valve 5. The outlet 1 and outlet 2 of the lifting directional valve 10 are respectively connected to the inlet 1 of the tilt directional valve 11. The outlet 3 of the lifting directional valve 10 is connected to the working port A1.

[0026] The inlet 2 of the tilting directional valve 11 is connected to the inlet P1 and inlet P2 of the integrated directional valve 5, the inlet 3 is connected to the working port B2, the outlet 1 is connected to the inlet 1 of the side shift directional valve 12, the outlet 2 is connected to the working port A2, and the outlet 3 is connected to the oil tank 18 via the return port 2T of the integrated directional valve 5.

[0027] The inlet 2 of the side shift directional valve 12 is connected to the inlet P1 and inlet P2 of the integrated directional valve 5, the inlet 3 is connected to the working port B3, the outlet 1 is connected to the inlet 1 of the adjustable pitch directional valve 13, the outlet 2 is connected to the working port A3, and the outlet 3 is connected to the oil tank 18 via the return port 2T of the integrated directional valve 5.

[0028] The inlet 2 of the pitch control valve 13 is connected to the inlet P1 and inlet P2 of the integrated directional valve 5 respectively, the inlet 3 is connected to the working port B4, the outlet 1 is connected to the oil tank 18, the outlet 2 is connected to the working port A4, and the outlet 3 is connected to the oil tank 18 via the return port 2T of the integrated directional valve 5.

[0029] Actuation unit: Four sets of dedicated working cylinders are used to convert hydraulic energy into mechanical energy and directly drive the forklift to complete the corresponding operation. These include lifting cylinder 14, tilting cylinder 15, side shifting cylinder 16, and adjusting cylinder 17.

[0030] Auxiliary unit: Oil tank 18, used to store hydraulic oil.

[0031] The working process of the energy recovery hydraulic system in a manual forklift is as follows.

[0032] The lifting cylinder 14 can perform a single or combined lifting action, i.e., the lifting directional valve 10 switches to the lifting position: When the lifting directional valve push rod is manually pushed or combined with other push rods, the lifting pilot directional valve 19 is in the connected position. A portion of the hydraulic oil output from the two-quadrant pump 3 obtains a stable pilot pressure through the inlet P2 of the integrated directional valve 5, the pilot pressure reducing valve 6, and the throttle orifice 7. The pilot oil returns to the oil tank 18 through the lifting pilot directional valve 19, and the pilot pressure is zero. The directional valve 18 is in the connected position under the action of the spring, and the directional valve 29 is in the one-way connected position under the action of the spring. When the lifting directional valve 10 is in single action, the hydraulic oil output from the hydraulic pump 2 merges with the hydraulic oil output from the two-quadrant pump 3 through the directional valve 29 and then flows through the lifting directional valve 19. 0. When the working port A1 enters the large chamber of the lifting cylinder 14, the lifting cylinder 14 extends. When the lifting directional valve 10 and at least one of the tilt directional valve 11, side shift directional valve 12, and pitch adjustment directional valve 13 operate in combination, a portion of the hydraulic oil output from the hydraulic pump 2 merges with a portion of the hydraulic oil output from the two-quadrant pump 3 through the second directional valve 9 and then enters the large chamber of the lifting cylinder 14 through the lifting directional valve 10 and the working port A1, and the lifting cylinder 14 extends. Another portion of the hydraulic oil output from the hydraulic pump 2 and another portion of the hydraulic oil output from the two-quadrant pump 3 merge through the first directional valve 8 and then enters the corresponding cylinder through at least one of the tilt directional valve 11, side shift directional valve 12, and pitch adjustment directional valve 13, and completes the corresponding action.

[0033] When the lifting cylinder descends in a single action, the lifting directional valve 10 is switched to the descending position, while the tilt directional valve 11, the side shift directional valve 12, and the pitch directional valve 13 remain inactive. When the lifting directional valve push rod is manually pulled, the lifting pilot directional valve 19 is in the cut-off position, while the tilt pilot directional valve 20, the side shift pilot directional valve 21, and the pitch directional valve 22 are all in the connected position. The hydraulic oil in the large chamber of the lifting cylinder obtains a stable pilot pressure through the pilot pressure reducing valve 6 and the throttle orifice 7. The pilot oil returns to the oil tank through the tilt pilot directional valve 20, the lateral pilot directional valve 21, and the pitch pilot directional valve 22. The pilot pressure is zero, the directional valve 1 8 is in the connected position, and the directional valve 2 9 is in the one-way connected position. The remaining hydraulic oil in the large chamber of the lifting cylinder 14 can only enter the two-quadrant pump 3 through the lifting directional valve 10 under the action of gravity. The two-quadrant pump 3 drives the two-quadrant pump motor 4 to generate electricity and store it in the battery.

[0034] The lifting cylinder descends in conjunction with other cylinder actions, i.e., the lifting directional valve 10 switches to the descending position, and at least one of the tilt directional valve 11, the side shift directional valve 12, and the adjusting directional valve 13 switches: when the lifting directional valve push rod and other push rods are manually pulled, the lifting pilot directional valve 19 is in the off position, and at least one of the tilt pilot directional valve 20, the side shift pilot directional valve 21, and the adjusting pilot directional valve 22 is in the off position; the hydraulic oil in the large chamber of the lifting cylinder passes through the pilot pressure reducing valve 6 and the throttle orifice. 7. Once a stable pilot pressure is obtained, the pilot oil circuits of the lifting pilot directional valve 19 and other pilot directional valves (tilt pilot directional valve 20, side shift pilot directional valve 21, and pitch control pilot directional valve 22) are closed, and the pilot pressure is 30 bar. Directional valves 8 and 9 are both in the off position. The remaining hydraulic oil in the large chamber of the lifting cylinder 14, under the influence of gravity, can only enter the second-quadrant pump 3 through the lifting directional valve 10. The second-quadrant pump 3 drives the second-quadrant pump motor 4 to generate electricity, which is then stored in the battery. The hydraulic oil output from the hydraulic pump 2 enters the corresponding cylinder through at least one of the tilt directional valve 11, side shift directional valve 12, and pitch control directional valve 13 to complete the corresponding action.

[0035] The core of this invention lies in abandoning the traditional forklift hydraulic system's reliance on electronically controlled components (such as solenoid valves and PLC controllers) for oil circuit switching. Instead, it employs a pure hydraulically controlled pilot-operated reversing mechanism. Through pressure changes and on / off states in the pilot oil circuit, it drives the main oil circuit components (such as reversing valve 8, reversing valve 9, and the work action reversing valve), thereby achieving precise switching between the energy recovery oil circuit and the work drive oil circuit, ultimately realizing the recovery and utilization of gravitational potential energy. This invention can be based on existing hydraulic systems without requiring radical modifications to the original structure. Through low-cost optimization and functional upgrades, and by adding a pilot-operated reversing oil circuit and hydraulically controlled reversing valves 8 and 9, it achieves efficient recovery and secondary utilization of gravitational potential energy without the need for an electronic control system. This ultimately achieves the core goals of high efficiency, low cost, and easy mass production, providing practical technical support for the transformation of forklifts towards a "green and efficient" direction.

[0036] Example 2 Based on the manual forklift energy recovery hydraulic system described in Embodiment 1, this embodiment provides a manual forklift equipped with the manual forklift energy recovery hydraulic system described in Embodiment 1.

[0037] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A manual forklift energy recovery hydraulic system, characterized in that, include: A hydraulic pump (2) for supplying hydraulic oil to the working cylinder, the hydraulic pump (2) being drivenly connected to a hydraulic pump motor (1); A two-quadrant pump (3) is used to supply hydraulic oil to the working cylinder or to recover the gravitational potential energy of the hydraulic oil through an integrated directional valve (5). The two-quadrant pump (3) is connected to a two-quadrant pump motor (4) for transmission. The integrated directional valve (5) has its inlet P1 connected to the outlet of the hydraulic pump (2), its inlet P2 connected to the outlet of the two-quadrant pump (3), its working port A1 connected to the large chamber of the lifting cylinder (14), its working port A2 connected to the large chamber of the tilting cylinder (15), its working port B2 connected to the small chamber of the tilting cylinder (15), its working port A3 connected to the left chamber of the side-shifting cylinder (16), its working port B3 connected to the right chamber of the side-shifting cylinder (16), its working port A4 connected to the left chamber of the adjusting cylinder (17), and its working port B4 connected to the right chamber of the adjusting cylinder (17). The integrated directional valve (5) includes: The pilot pressure reducing valve (6) is connected to the inlet P2 of the integrated directional valve (5) and the outlet is connected to the inlet of the throttle orifice (7); the outlet of the throttle orifice (7) is connected to the control end of the directional valve one (8), the control end of the directional valve two (9), the inlet of the lifting pilot directional valve (19), and the inlet of the tilting pilot directional valve (20). The outlet of the tilt pilot directional valve (20) is connected to the inlet of the side shift pilot directional valve (21), the outlet of the side shift pilot directional valve (21) is connected to the inlet of the pitch pilot directional valve (22), and the outlet of the pitch pilot directional valve (22) and the outlet of the lifting pilot directional valve (19) are connected to the oil tank (18). The inlet of the first reversing valve (8) is connected to the inlet P2 of the integrated reversing valve (5), and the outlet of the first reversing valve (8) is connected to the inlet 2 of the tilt reversing valve (11), the inlet 2 of the side shift reversing valve (12), and the inlet 2 of the pitch reversing valve (13), respectively. The inlet of the second reversing valve (9) is connected to the inlet P1 of the integrated reversing valve (5), and the outlet of the second reversing valve (9) is connected to the inlet one and inlet three of the lifting reversing valve (10) respectively. The inlet 2 of the lifting directional valve (10) is connected to the inlet P1 of the integrated directional valve (5), the outlet 1 and outlet 2 of the lifting directional valve (10) are respectively connected to the inlet 1 of the tilt directional valve (11), and the outlet 3 of the lifting directional valve (10) is connected to the working port A1. The inlet 2 of the tilting directional valve (11) is connected to the inlet P1 and inlet P2 of the integrated directional valve (5), the inlet 3 is connected to the working port B2, the outlet 1 is connected to the inlet 1 of the side shift directional valve (12), the outlet 2 is connected to the working port A2, and the outlet 3 is connected to the oil tank (18). The inlet 2 of the side shift directional valve (12) is connected to the inlet P1 and inlet P2 of the integrated directional valve (5), the inlet 3 is connected to the working port B3, the outlet 1 is connected to the inlet 1 of the adjustable pitch directional valve (13), the outlet 2 is connected to the working port A3, and the outlet 3 is connected to the oil tank (18). The inlet 2 of the pitch control valve (13) is connected to the inlet P1 and inlet P2 of the integrated directional valve (5), the inlet 3 is connected to the working port B4, the outlet 1 is connected to the oil tank (18), the outlet 2 is connected to the working port A4, and the outlet 3 is connected to the oil tank (18).

2. The manual forklift energy recovery hydraulic system according to claim 1, characterized in that, When the lifting directional valve (10) switches to the rising position, the lifting pilot directional valve (19) is in the connected position. A portion of the hydraulic oil output by the two-quadrant pump (3) enters the oil tank (18) through the pilot pressure reducing valve (6), the throttle orifice (7), and the lifting pilot directional valve (19). The pilot pressure is zero, the first directional valve (8) is in the connected position, and the second directional valve (9) is in the one-way connected position. When the lifting directional valve (10) operates alone, the hydraulic oil output by the hydraulic pump (2) merges with the hydraulic oil output by the second directional valve (9) and the second quadrant pump (3) and then enters the large chamber of the lifting cylinder (14) through the lifting directional valve (10) and working port A1, and the lifting cylinder (14) extends. When the lifting directional valve (10) and at least one of the tilt directional valve (11), side shift directional valve (12), and pitch adjustment directional valve (13) are in combined operation, a portion of the hydraulic oil output by the hydraulic pump (2) is combined with a portion of the hydraulic oil output by the second directional valve (9) and the second quadrant pump (3) and then enters the large chamber of the lifting cylinder (14) through the lifting directional valve (10) and working port A1, and the lifting cylinder (14) extends out; another portion of the hydraulic oil output by the hydraulic pump (2) and another portion of the hydraulic oil output by the second quadrant pump (3) are combined with the first directional valve (8) and then enter the corresponding cylinder through at least one of the tilt directional valve (11), side shift directional valve (12), and pitch adjustment directional valve (13) and complete the corresponding action.

3. The manual forklift energy recovery hydraulic system according to claim 1, characterized in that, When the lifting directional valve (10) switches to the lowering position, and the tilt directional valve (11), side shift directional valve (12), and adjusting directional valve (13) are not activated, the lifting pilot directional valve (19) is in the cut-off position, and the tilt pilot directional valve (20), side shift pilot directional valve (21), and adjusting directional valve (22) are all in the connected position. A portion of the hydraulic oil in the large chamber of the lifting cylinder (14) passes through the pilot pressure reducing valve (6) and the throttle orifice ( 7) The tilt pilot directional valve (20), the side shift pilot directional valve (21), and the pitch pilot directional valve (22) enter the oil tank (18). The pilot pressure is zero. The directional valve one (8) is in the connected position and the directional valve two (9) is in the one-way connected position. The remaining hydraulic oil in the large chamber of the lifting cylinder (14) enters the two-quadrant pump (3) through the lifting directional valve (10) and drives the two-quadrant pump motor (4) to generate electricity through the two-quadrant pump (3).

4. The manual forklift energy recovery hydraulic system according to claim 1, characterized in that, When the lifting directional valve (10) switches to the lowering position, at least one of the tilt directional valve (11), the side shift directional valve (12), and the pitch directional valve (13) switches, the lifting pilot directional valve (19) is in the cut-off position, and at least one of the tilt pilot directional valve (20), the side shift pilot directional valve (21), and the pitch pilot directional valve (22) is in the cut-off position. A portion of the hydraulic oil in the large chamber of the lifting cylinder (14) enters the control end of the first directional valve (8) and the second directional valve (9) through the pilot pressure reducing valve (6) and the throttle orifice (7). Both the first directional valve (8) and the second directional valve (9) are in the cut-off position. The remaining hydraulic oil in the large chamber of the lifting cylinder (14) enters the second quadrant pump (3) through the lifting directional valve (10) and drives the second quadrant pump motor (4) to generate electricity through the second quadrant pump (3).

5. The manual forklift energy recovery hydraulic system according to claim 1, characterized in that, The hydraulic pump (2) is a gear pump.

6. The manual forklift energy recovery hydraulic system according to claim 1, characterized in that, The lifting directional valve (10) and the lifting pilot directional valve (19) switch in tandem, the tilt directional valve (11) and the tilt pilot directional valve (20) switch in tandem, the side shift directional valve (12) and the side shift pilot directional valve (21) switch in tandem, and the pitch directional valve (13) and the pitch pilot directional valve (22) switch in tandem.

7. The manual forklift energy recovery hydraulic system according to claim 1, characterized in that, It also includes a storage battery, which is electrically connected to the hydraulic pump motor (1) and the two-quadrant pump motor (4) respectively.

8. A manual forklift, characterized in that, The manual forklift is equipped with the manual forklift energy recovery hydraulic system as described in any one of claims 1 to 7.

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