Hydraulic control system for a three-way vehicle

Abstract

The utility model relates to the technical field of forklift hydraulic pressure and concretely discloses a hydraulic control system of three -dimensional car, including system oil port, oil tank, big arm control oil circuit, small arm control oil circuit and distribution oil circuit, distribution oil circuit is equipped with priority valve and fifth electromagnetic proportional valve, priority valve can supply oil liquid alone big arm control oil circuit or small arm control oil circuit, can also supply two control oil circuits simultaneously, big arm, small arm control oil circuit all adopt parallel electromagnetic proportional valve and control the lifting of its oil cylinder respectively, the utility model discloses through oil circuit design, has broken the interlocking limit of big arm and small arm action, operator can control small arm lifting independently while controlling big arm lifting, realizes compound action to the height of gantry and extension length can be adjusted simultaneously in carrying, has remarkably shortened the operation cycle time, has improved the warehousing and carrying efficiency, system control is accurate, runs smoothly and has high reliability.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic control technology for forklifts, and specifically to a hydraulic control system for a three-way forklift. Background Technology

[0002] A three-way forklift is a special type of forklift whose forks can not only be raised, lowered, and tilted like those of a traditional forklift, but can also rotate in the horizontal plane. It is usually equipped with a multi-stage telescopic mast system (usually including a boom and a jib) to enable the storage and retrieval of goods in narrow aisles. Its mast movement is driven by a hydraulic system, which typically includes a first lifting cylinder that drives the boom to rise and fall and a second lifting cylinder that drives the jib (or inner mast) to rise and fall.

[0003] Traditional three-way mast hydraulic control systems typically employ interlocking or sequential control of the boom and gantry hydraulic circuits. Specifically, when the boom is raised or lowered, the lower arm's raising or lowering function is locked and cannot move; conversely, when the lower arm is moved, the boom is also locked. While this design ensures system safety and prevents misoperation, it is inefficient in complex operating conditions requiring frequent adjustments to cargo height and mast extension length. For example, when moving pallets to different shelf heights, the boom must first be raised and positioned, then the control mode must be switched, and finally the lower arm must be extended and positioned. This entire process involves waiting and switching time, impacting operational efficiency. Utility Model Content

[0004] This utility model was developed in consideration of the aforementioned problems. The purpose of this utility model is to provide a hydraulic control system for a three-way vehicle, which enables independent or combined control of the boom and forearm, thereby shortening the operation time.

[0005] To achieve the above objectives, this utility model provides a hydraulic control system for a three-way lifting vehicle. The three-way lifting vehicle is equipped with a first lifting cylinder for driving the boom's lifting and lowering and a second lifting cylinder for driving the forearm's lifting and lowering. The hydraulic control system includes a system oil port, an oil tank, a boom control oil circuit, a forearm control oil circuit, and a distribution oil circuit.

[0006] The boom control oil circuit includes a first electromagnetic proportional valve and a second electromagnetic proportional valve arranged in parallel. The oil inlet of the first electromagnetic proportional valve is connected to the system oil port, and its oil outlet is connected to the rodless chamber of the first lifting cylinder. The oil inlet of the second electromagnetic proportional valve is connected to the rodless chamber of the first lifting cylinder, and its oil outlet is connected to the oil tank.

[0007] The boom control oil circuit includes a third electromagnetic proportional valve and a fourth electromagnetic proportional valve arranged in parallel. The oil outlet of the third electromagnetic proportional valve is connected to the rodless chamber of the second lifting cylinder, the oil inlet of the fourth electromagnetic proportional valve is connected to the rodless chamber of the second lifting cylinder, and its oil outlet is connected to the oil tank.

[0008] The oil distribution circuit includes a priority valve and a fifth electromagnetic proportional valve. The priority valve is arranged between the system oil port and the first electromagnetic proportional valve. The oil inlet of the priority valve is connected to the system oil port. The priority valve has a first oil outlet and a second oil outlet. The first oil outlet is connected to the oil inlet of the first electromagnetic proportional valve, the second oil outlet is connected to the oil inlet of the fifth electromagnetic proportional valve, and the oil outlet of the fifth electromagnetic proportional valve is connected to the oil inlet of the third electromagnetic proportional valve.

[0009] According to the hydraulic control system of the three-way vehicle described above, the first electromagnetic proportional valve is provided with a first electromagnet for controlling its opening size, the second electromagnetic proportional valve is provided with a second electromagnet for controlling its opening size, the third electromagnetic proportional valve is provided with a third electromagnet for controlling its opening size, the fourth electromagnetic proportional valve is provided with a fourth electromagnet for controlling its opening size, and the fifth electromagnetic proportional valve is provided with a fifth electromagnet for controlling its opening size.

[0010] According to the hydraulic control system of the three-way vehicle described above, the boom control oil circuit further includes a sixth electromagnetic proportional valve arranged in series with the second electromagnetic proportional valve. The oil inlet of the sixth electromagnetic proportional valve is connected to the oil outlet of the second electromagnetic proportional valve, and the oil outlet of the sixth electromagnetic proportional valve is connected to the oil tank.

[0011] The sixth electromagnetic proportional valve is equipped with a sixth electromagnet.

[0012] According to the hydraulic control system of the three-way vehicle described above, the distribution oil circuit further includes a first filter, which is located between the system oil port and the priority valve. The oil inlet of the first filter is connected to the system oil port, and its oil outlet is connected to the oil inlet of the priority valve.

[0013] According to the hydraulic control system of the three-way vehicle described above, the boom control oil circuit further includes a second filter. The second filter is located between the first lifting cylinder and the second electromagnetic proportional valve. The oil inlet of the second filter is connected to the rodless chamber of the first lifting cylinder, and its oil outlet is connected to the oil inlet of the second electromagnetic proportional valve.

[0014] The boom control oil circuit also includes a third filter, which is located between the second lifting cylinder and the fourth electromagnetic proportional valve. The oil inlet of the third filter is connected to the rodless chamber of the second lifting cylinder, and its oil outlet is connected to the oil inlet of the fourth electromagnetic proportional valve.

[0015] According to the hydraulic control system of the three-way vehicle described above, a first check valve is provided between the oil outlet of the fifth electromagnetic proportional valve and the oil inlet of the third electromagnetic proportional valve. The opening of the first check valve faces the oil inlet of the third electromagnetic proportional valve, and a first pipe is provided between the oil outlet of the first check valve and the oil inlet of the third electromagnetic proportional valve.

[0016] The hydraulic control system of the three-way vehicle described above also includes a rotation control oil circuit. The three-way vehicle is also equipped with a rotary motor for controlling the rotation of the forks. The rotary motor has an A port and a B port. The rotation control oil circuit is arranged between the first pipe and the rotary motor and is used to supply oil to the A port or the B port of the rotary motor.

[0017] According to the hydraulic control system of the three-way vehicle described above, the rotation control oil circuit includes a first electromagnetic directional valve. The first electromagnetic directional valve has a first variable oil port connected to port A and a second variable oil port connected to port B. The oil inlet of the first electromagnetic directional valve is connected to the first pipeline, and the oil return port of the first electromagnetic directional valve is connected to the oil tank.

[0018] According to the hydraulic control system of the three-way vehicle described above, the first electromagnetic directional valve is configured as a three-position four-way directional valve. The first electromagnetic directional valve is equipped with a seventh electromagnet and an eighth electromagnet. When the seventh electromagnet is energized, the oil inlet of the first electromagnetic directional valve is connected to the second variable oil port, and the oil return port of the first electromagnetic directional valve is connected to the first variable oil port. When the eighth electromagnet is energized, the oil inlet of the first electromagnetic directional valve is connected to the first variable oil port, and the oil return port of the first electromagnetic directional valve is connected to the second variable oil port.

[0019] According to the hydraulic control system of the three-way vehicle described above, the rotary control oil circuit further includes a speed control valve, which is located between the first pipeline and the first electromagnetic directional valve. The oil inlet of the speed control valve is connected to the first pipeline, and the oil outlet of the speed control valve is connected to the oil inlet of the first electromagnetic directional valve.

[0020] This utility model has the following beneficial effects:

[0021] 1. Because the hydraulic circuit is independently distributed and adjustable, the operator can control the boom to rise or fall while simultaneously adjusting the forearm to rise or fall, and vice versa. This breaks the original system's "either / or" interlocking limitation and greatly shortens the time for switching pallets at different heights.

[0022] 2. Each hydraulic circuit is controlled by an electromagnetic proportional valve, which can proportionally adjust the inlet and outlet flow of the hydraulic cylinder, thereby achieving stepless and smooth control of the lifting speed of the boom and arm, and high operating precision.

[0023] 3. The oil distribution circuit can also distribute oil to the rotary oil circuit, thus realizing that one system oil port supplies multiple control oil circuits. The overall oil circuit integration of the three-way vehicle is high, reducing costs.

[0024] 4. A first filter is installed between the system oil port and the priority valve, a second filter is installed between the rodless chamber of the first lifting cylinder and the second electromagnetic proportional valve, and a third filter is installed between the rodless chamber of the second lifting cylinder and the fourth electromagnetic proportional valve. This ensures the purity of the oil entering each valve body and avoids damage to each valve body. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall oil circuit in an embodiment.

[0026] In the picture:

[0027] 100. System oil port;

[0028] 200. Fuel tank;

[0029] 300. Boom control oil circuit; 310. First electromagnetic proportional valve; 311. First electromagnet; 320. Second electromagnetic proportional valve; 321. Second electromagnet; 330. Sixth electromagnetic proportional valve; 331. Sixth electromagnet; 340. Second filter;

[0030] 400. Arm control oil circuit; 410. Third electromagnetic proportional valve; 411. Third electromagnet; 420. Fourth electromagnetic proportional valve; 421. Fourth electromagnet; 430. Third filter;

[0031] 500. Oil distribution circuit; 510. Priority valve; 520. Fifth electromagnetic proportional valve; 521. Fifth electromagnet; 530. First filter; 540. First check valve;

[0032] 600. Rotary control oil circuit; 610. First solenoid directional valve; 611. Seventh electromagnet; 612. Eighth electromagnet; 620. Speed ​​control valve. Detailed Implementation

[0033] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0034] like Figure 1 As shown, a hydraulic control system for a three-way vehicle includes a system oil port 100, an oil tank 200, a boom control oil circuit 300, a forearm control oil circuit 400, and a distribution oil circuit 500. In this embodiment, the oil is distributed through the distribution oil circuit 500 to achieve individual or joint control of the boom and forearm, thereby improving the efficiency of switching pallets at different heights.

[0035] In this embodiment, the three-way vehicle is equipped with a first lifting cylinder for driving the boom to rise and fall, a second lifting cylinder for driving the fork to rise and fall, and a rotary cylinder for controlling the rotation of the forks.

[0036] The boom control hydraulic circuit includes a first electromagnetic proportional valve 310 and a second electromagnetic proportional valve 320 connected in parallel. The inlet of the first electromagnetic proportional valve 310 is connected to the system oil port 100, and its outlet is connected to the rodless chamber of the first lifting cylinder. A first electromagnet 311 is provided on the first electromagnetic proportional valve 310. When the first electromagnet 311 is energized, it controls the opening of the first electromagnetic proportional valve 310 according to the magnitude of the energized current, and can precisely control the opening size. At this time, the hydraulic fluid can enter the rodless chamber of the first lifting cylinder through the first electromagnetic proportional valve 310, driving the piston rod of the first lifting cylinder to move upward, thereby driving the boom to rise. During this process, the lifting speed of the boom can be adjusted according to the opening size of the first electromagnetic proportional valve 310. The size of the opening of the second electromagnetic proportional valve 320 is determined by the size of the opening of the first lifting cylinder. The oil inlet of the second electromagnetic proportional valve 320 is connected to the rodless chamber of the first lifting cylinder, and its oil outlet is connected to the oil tank 200. A second electromagnet 321 is provided on the second electromagnetic proportional valve 320. The second electromagnet 321 controls the opening size of the second electromagnetic proportional valve 320 according to the energized current information. At this time, the hydraulic oil in the rodless chamber of the first lifting cylinder can be discharged into the oil tank 200 through the second electromagnetic proportional valve 320, driving the boom to descend. During this process, the descent speed of the boom can be determined according to the opening size of the second electromagnetic proportional valve 320. Therefore, in this embodiment, when the boom rises, the first electromagnet 311 is energized and the second electromagnet 321 is not energized. When the boom descends, the second electromagnet 321 is energized and the first electromagnet 311 is not energized.

[0037] Furthermore, the boom control oil circuit 300 also includes a sixth electromagnetic proportional valve 330 arranged in series with the second electromagnetic proportional valve 320. The oil inlet of the sixth electromagnetic proportional valve 330 is connected to the oil outlet of the second electromagnetic proportional valve 320, and the oil outlet of the sixth electromagnetic proportional valve 330 is connected to the oil tank 200. The sixth electromagnetic proportional valve 330 is equipped with a sixth electromagnet 331. The sixth electromagnetic proportional valve 330 and the second electromagnetic proportional valve 320 can achieve a "pressure holding" effect, avoiding large leakage of a single electromagnetic proportional valve due to excessive boom weight. By using two electromagnetic proportional valves, even if both have leakage, the total leakage is less, avoiding a significant drop in boom weight due to leakage. At the same time, in extreme cases, if one of the electromagnetic proportional valves (such as the second electromagnetic proportional valve 320) is accidentally opened to its maximum due to electrical or mechanical failure, the sixth electromagnetic proportional valve 330 can still act as a controllable throttling element to prevent the boom from stalling and falling due to unobstructed oil return, thus buying time for fault handling and avoiding equipment damage and personal injury.

[0038] Furthermore, the boom control hydraulic circuit 300 also includes a second filter 340, which is located between the first lifting cylinder and the second electromagnetic proportional valve 320. The inlet of the second filter 340 is connected to the rodless chamber of the first lifting cylinder, and its outlet is connected to the inlet of the second electromagnetic proportional valve 320. The second electromagnetic proportional valve 320 is a core precision component for controlling the boom descent speed. The clearance between its valve core and valve sleeve is extremely small, making it extremely sensitive to oil contamination. When the boom descends, the oil flowing back from the rodless chamber of the cylinder may contain: products produced inside the cylinder. The filter removes wear particles (such as those from seals, cylinders / piston rods) and contaminants circulating from other parts of the system. The second filter 340 is precisely positioned before the contaminated oil enters the second electromagnetic proportional valve 320, acting as a "dedicated firewall" to effectively intercept solid particles and prevent them from causing the proportional valve core to stick, the throttle orifice to become blocked, or abnormally worn. At the same time, since the sixth electromagnetic proportional valve 330 is connected in series with the second electromagnetic proportional valve 320, the filter also protects the sixth electromagnetic proportional valve 330, thus achieving protection for two core control components with a single component.

[0039] The boom control oil circuit 400 includes a third electromagnetic proportional valve 410 and a fourth electromagnetic proportional valve 420 connected in parallel. The oil outlet of the third electromagnetic proportional valve 410 is connected to the rodless chamber of the second lifting cylinder. A third electromagnet 411 is provided on the third electromagnetic proportional valve 410. The third electromagnet 411 controls the opening size of the third electromagnetic proportional valve 410 through current information. When the third electromagnet 411 is energized, oil can enter the rodless chamber of the second lifting cylinder through the third electromagnetic proportional valve 410, driving its piston rod to extend and realize the lifting action of the boom. Of course, this oil comes from the oil distributed by the distribution oil circuit 500. The oil inlet of the fourth electromagnetic proportional valve 420 is connected to the rodless chamber of the second lifting cylinder, and its outlet is connected to the oil tank 200. A fourth electromagnet 421 is provided on the fourth electromagnetic proportional valve 420. The fourth electromagnet 421 can control the opening size of the fourth electromagnetic proportional valve 420 according to the current information. When the fourth electromagnetic proportional valve 420 is open, the oil in the second lifting cylinder can be discharged into the oil tank 200 through the fourth proportional valve to realize the lowering of the boom. Therefore, when the boom rises, the third electromagnet 411 is energized and the fourth electromagnet 421 is de-energized. When the boom lowers, the third electromagnet 411 is de-energized and the fourth electromagnet 421 is energized.

[0040] Furthermore, the boom control oil circuit 400 also includes a third filter 430, which is located between the second lifting cylinder and the fourth electromagnetic proportional valve 420. The oil inlet of the third filter 430 is connected to the rodless chamber of the second lifting cylinder, and its oil outlet is connected to the oil inlet of the fourth electromagnetic proportional valve 420. The fourth electromagnetic proportional valve 420 is the only throttling element that controls the boom descent speed, and its valve core is extremely sensitive to contaminant particles. This filter is directly deployed on the path that the oil must take after flowing through the cylinder and before entering the proportional valve, forming a "point-to-point" direct protection for the key component. The oil flowing back from the rodless chamber of the boom cylinder is a high-risk contamination flow. The third filter 430 can effectively intercept these contaminants, preventing them from causing the valve core of the fourth electromagnetic proportional valve 420 to jam, the throttling orifice to become blocked, or abnormal wear, thus fundamentally avoiding the risk of uncontrolled boom descent due to valve failure.

[0041] The distribution oil circuit 500 is crucial for the flow distribution of the entire system. The distribution oil circuit 500 includes a priority valve 510 and a fifth electromagnetic proportional valve 520. The priority valve 510 is positioned between the system oil port 100 and the first electromagnetic proportional valve 310. The inlet of the priority valve 510 is connected to the system oil port 100. The priority valve 510 has a first outlet and a second outlet. The first outlet is connected to the inlet of the first electromagnetic proportional valve 310, and the second outlet is connected to the inlet of the fifth electromagnetic proportional valve 520. The outlet of the fifth electromagnetic proportional valve 520 is connected to the inlet of the third electromagnetic proportional valve 410. A fifth electromagnet 5 is installed on the fifth electromagnetic proportional valve 520 to control its opening size. 21. When the upper arm moves alone, the fifth electromagnetic proportional valve 520 remains normally closed. At this time, the fifth electromagnet 521 remains de-energized, and the first electromagnet 311 is energized, thus realizing the raising action of the upper arm. When the second electromagnet 321 and the sixth electromagnet 331 are energized, the lowering action of the upper arm is realized. When the forearm moves alone, the first electromagnetic proportional valve 310 remains normally closed. At this time, the first electromagnet 311 remains de-energized, and the fifth electromagnet 521 and the third electromagnet 411 are energized simultaneously. When the fourth electromagnet 421 is de-energized, the raising action of the forearm can be realized. When the fifth electromagnet 521 and the third electromagnet 411 are de-energized, and the fourth electromagnet 421 is energized, the lowering action of the forearm can be realized.

[0042] In this embodiment, when the upper arm rises alone, only the first electromagnet 311 is energized, and the other electromagnets are de-energized; when the upper arm descends alone, only the second electromagnet 321 and the sixth electromagnet 331 are energized, and the other electromagnets are de-energized; when the forearm rises alone, only the fifth electromagnet 521 and the third electromagnet 411 are energized, and the other electromagnets are de-energized; when the forearm descends alone, only the fourth electromagnet 421 is energized, and the other electromagnets are de-energized; when both the upper arm and forearm rise, the first electromagnet 311 and the fifth electromagnet 321 are energized. When the upper arm rises and the lower arm falls, the first electromagnet 311 and the fourth electromagnet 421 are energized, and the remaining electromagnets are de-energized; when the upper arm falls and the lower arm falls, the second electromagnet 321, the sixth electromagnet 331 and the fourth electromagnet 421 are energized, and the remaining electromagnets are de-energized; when the upper arm falls and the lower arm rises, the second electromagnet 321, the sixth electromagnet 331, the fifth electromagnet 521 and the third electromagnet 411 are energized, and the remaining electromagnets are de-energized.

[0043] By distributing the oil through the oil circuit 500, individual or combined movements of the boom and forearm can be achieved, thereby improving work efficiency.

[0044] Furthermore, the distribution oil circuit 500 also includes a first filter 530, which is located between the system oil port 100 and the priority valve 510. The inlet of the first filter 530 is connected to the system oil port 100, and its outlet is connected to the inlet of the priority valve 510. The system oil port 100 is the pressure oil output port of the hydraulic pump and is the "main source" of all working oil in the system. Setting a filter at this location means that the pressure oil that is about to enter the entire control system is filtered in its entirety. Before contaminants have the opportunity to enter and damage any branch circuit, they are intercepted at the source. This is the most cost-effective and efficient protection strategy.

[0045] Furthermore, a first check valve 540 is provided between the oil outlet of the fifth electromagnetic proportional valve 520 and the oil inlet of the third electromagnetic proportional valve 410. The opening of the first check valve 540 faces the oil inlet of the third electromagnetic proportional valve 410, and a first pipe is provided between the oil outlet of the first check valve 540 and the oil inlet of the third electromagnetic proportional valve 410. This check valve clearly stipulates that the oil can only flow from the fifth electromagnetic proportional valve 520 to the arm control oil circuit 400 (via the third electromagnetic proportional valve 410). This prevents the oil from flowing back from the arm control oil circuit 400 to the bypass oil circuit of the priority valve 510, ensuring that the arm control oil circuit 400 becomes a relatively independent unit in function, and its pressure state will not be easily disturbed by the pressure fluctuations of the upstream priority valve 510 or other parallel circuits.

[0046] Meanwhile, the design of the first pipeline makes it a "clean," "controlled," and "one-way" pressure source pipeline that is led out from the bypass port of the priority valve 510, regulated by the fifth electromagnetic proportional valve 520, and isolated by the first one-way valve 540, providing a safe and reliable pressure source interface for the integration of other working circuits.

[0047] In this embodiment, the hydraulic control system also includes a rotary control oil circuit 600. The three-way vehicle is also equipped with a rotary motor for controlling the rotation of the forks. The rotary motor has ports A and B. The rotary control oil circuit 600 is arranged between the first pipe and the rotary motor and is used to supply oil to port A or port B of the rotary motor. The rotary control oil circuit 600 directly draws oil from the first pipe that supplies oil to the boom, eliminating the need for a separate hydraulic power source consisting of a pump and valves for the rotary motor. This greatly simplifies the system structure, reduces the number of core components such as hydraulic pumps, motors, oil tanks 200, and filters, and reduces the system space occupied. At the same time, the rotary circuit shares the flow distribution and control unit consisting of the priority valve 510 and the fifth electromagnetic proportional valve 520, as well as the upstream first filter 530. This avoids redundant setup and significantly reduces manufacturing costs and system complexity.

[0048] When oil is supplied to port A of the rotary motor, the forks can rotate clockwise; when oil is supplied to port B of the rotary motor, the forks can rotate counterclockwise.

[0049] Furthermore, the rotary control oil circuit 600 includes a first electromagnetic directional valve 610. The first electromagnetic directional valve 610 has a first variable oil port connected to port A and a second variable oil port connected to port B. The oil inlet of the first electromagnetic directional valve 610 is connected to the first pipeline, and the oil return port of the first electromagnetic directional valve 610 is connected to the oil tank 200. The flow path can be switched by the energization status, thereby realizing the switching of oil supply to port A and port B.

[0050] Furthermore, the first electromagnetic directional valve 610 is configured as a three-position four-way directional valve. The first electromagnetic directional valve 610 is equipped with a seventh electromagnet 611 and an eighth electromagnet 612. When the seventh electromagnet 611 is energized, the oil inlet of the first electromagnetic directional valve 610 is connected to the second variable oil port, and the oil return port of the first electromagnetic directional valve 610 is connected to the first variable oil port. When the eighth electromagnet 612 is energized, the oil inlet of the first electromagnetic directional valve 610 is connected to the first variable oil port, and the oil return port of the first electromagnetic directional valve 610 is connected to the second variable oil port. By switching the energization of the seventh electromagnet 611 and the eighth electromagnet 612, the flow channel is switched. When both the seventh electromagnet 611 and the eighth electromagnet 612 are de-energized, the first electromagnetic directional valve 610 is in the neutral position, and at this time the first electromagnetic directional valve 610 is closed.

[0051] Furthermore, the rotation control oil circuit 600 also includes a speed control valve 620, which is located between the first pipeline and the first solenoid directional valve 610. The oil inlet of the speed control valve 620 is connected to the first pipeline, and the oil outlet of the speed control valve 620 is connected to the oil inlet of the first solenoid directional valve 610. The speed control valve 620 can control the speed of the oil flowing into the first solenoid directional valve 610, thereby achieving the purpose of controlling the rotation speed of the forks.

[0052] Of course, in addition to the rotary control oil circuit 600, other control oil circuits can also be connected.

[0053] The technical solution of this utility model has been described in detail above with reference to the accompanying drawings. The described embodiments are used to help understand the concept of this utility model. The specific embodiments described herein are merely illustrative examples of the spirit of this utility model. Those skilled in the art to which this utility model pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, but without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

[0054] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0055] Furthermore, in this utility model, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0056] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0057] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

Claims

1. A hydraulic control system for a three-way vehicle, wherein the three-way vehicle is equipped with a first lifting cylinder for driving the boom to rise and fall and a second lifting cylinder for driving the forearm to rise and fall, characterized in that, The hydraulic control system includes system oil ports, an oil tank, boom control oil circuits, forearm control oil circuits, and distribution oil circuits. The boom control oil circuit includes a first electromagnetic proportional valve and a second electromagnetic proportional valve arranged in parallel. The oil inlet of the first electromagnetic proportional valve is connected to the system oil port, and its oil outlet is connected to the rodless chamber of the first lifting cylinder. The oil inlet of the second electromagnetic proportional valve is connected to the rodless chamber of the first lifting cylinder, and its oil outlet is connected to the oil tank. The boom control oil circuit includes a third electromagnetic proportional valve and a fourth electromagnetic proportional valve arranged in parallel. The oil outlet of the third electromagnetic proportional valve is connected to the rodless chamber of the second lifting cylinder, the oil inlet of the fourth electromagnetic proportional valve is connected to the rodless chamber of the second lifting cylinder, and its oil outlet is connected to the oil tank. The oil distribution circuit includes a priority valve and a fifth electromagnetic proportional valve. The priority valve is arranged between the system oil port and the first electromagnetic proportional valve. The oil inlet of the priority valve is connected to the system oil port. The priority valve has a first oil outlet and a second oil outlet. The first oil outlet is connected to the oil inlet of the first electromagnetic proportional valve, the second oil outlet is connected to the oil inlet of the fifth electromagnetic proportional valve, and the oil outlet of the fifth electromagnetic proportional valve is connected to the oil inlet of the third electromagnetic proportional valve.

2. The hydraulic control system for a three-way vehicle according to claim 1, characterized in that, The first electromagnetic proportional valve is provided with a first electromagnet for controlling the size of its opening, the second electromagnetic proportional valve is provided with a second electromagnet for controlling the size of its opening, the third electromagnetic proportional valve is provided with a third electromagnet for controlling the size of its opening, the fourth electromagnetic proportional valve is provided with a fourth electromagnet for controlling the size of its opening, and the fifth electromagnetic proportional valve is provided with a fifth electromagnet for controlling the size of its opening.

3. The hydraulic control system for a three-way vehicle according to claim 1, characterized in that, The boom control oil circuit also includes a sixth electromagnetic proportional valve arranged in series with the second electromagnetic proportional valve. The oil inlet of the sixth electromagnetic proportional valve is connected to the oil outlet of the second electromagnetic proportional valve, and the oil outlet of the sixth electromagnetic proportional valve is connected to the oil tank. The sixth electromagnetic proportional valve is equipped with a sixth electromagnet.

4. The hydraulic control system for a three-way vehicle according to claim 1, characterized in that, The oil distribution circuit further includes a first filter, which is located between the system oil port and the priority valve. The oil inlet of the first filter is connected to the system oil port, and its oil outlet is connected to the oil inlet of the priority valve.

5. The hydraulic control system for a three-way vehicle according to claim 1, characterized in that, The boom control oil circuit also includes a second filter, which is located between the first lifting cylinder and the second electromagnetic proportional valve. The oil inlet of the second filter is connected to the rodless chamber of the first lifting cylinder, and its oil outlet is connected to the oil inlet of the second electromagnetic proportional valve. The boom control oil circuit also includes a third filter, which is located between the second lifting cylinder and the fourth electromagnetic proportional valve. The oil inlet of the third filter is connected to the rodless chamber of the second lifting cylinder, and its oil outlet is connected to the oil inlet of the fourth electromagnetic proportional valve.

6. The hydraulic control system for a three-way vehicle according to claim 1, characterized in that, A first check valve is provided between the oil outlet of the fifth electromagnetic proportional valve and the oil inlet of the third electromagnetic proportional valve. The opening of the first check valve faces the oil inlet of the third electromagnetic proportional valve, and a first pipe is provided between the oil outlet of the first check valve and the oil inlet of the third electromagnetic proportional valve.

7. The hydraulic control system for a three-way vehicle according to claim 6, characterized in that, It also includes a rotation control oil circuit. The three-way vehicle is also equipped with a rotary motor for controlling the rotation of the forks. The rotary motor has an A port and a B port. The rotation control oil circuit is arranged between the first pipe and the rotary motor and is used to supply oil to the A port or B port of the rotary motor.

8. The hydraulic control system for a three-way vehicle according to claim 7, characterized in that, The rotary control oil circuit includes a first electromagnetic directional valve, which has a first variable oil port connected to port A and a second variable oil port connected to port B. The oil inlet of the first electromagnetic directional valve is connected to the first pipeline, and the oil return port of the first electromagnetic directional valve is connected to the oil tank.

9. The hydraulic control system for a three-way vehicle according to claim 8, characterized in that, The first electromagnetic directional valve is configured as a three-position four-way directional valve. The first electromagnetic directional valve is equipped with a seventh electromagnet and an eighth electromagnet. When the seventh electromagnet is energized, the oil inlet of the first electromagnetic directional valve is connected to the second variable oil port, and the oil return port of the first electromagnetic directional valve is connected to the first variable oil port. When the eighth electromagnet is energized, the oil inlet of the first electromagnetic directional valve is connected to the first variable oil port, and the oil return port of the first electromagnetic directional valve is connected to the second variable oil port.

10. A hydraulic control system for a three-way vehicle according to claim 8, characterized in that, The rotary control oil circuit also includes a speed regulating valve, which is located between the first pipeline and the first electromagnetic directional valve. The oil inlet of the speed regulating valve is connected to the first pipeline, and the oil outlet of the speed regulating valve is connected to the oil inlet of the first electromagnetic directional valve.

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