A hydraulic control system for forklift capable of automatic driving and manual driving

Abstract

The present invention discloses a forklift hydraulic control system that can realize automatic driving and manual driving, and belongs to the technical field of electric forklift hydraulic systems. The pump oil outlet is connected to the selection valve; the first oil circuit of the selection valve is connected to the multi-way valve, and the second oil circuit of the selection valve is connected to the priority valve; the priority valve oil outlet A is respectively connected to the first solenoid valve and the second solenoid valve; the first solenoid valve is connected to the lifting cylinder, and the second solenoid valve is connected to the tilting cylinder; the PF port of the priority valve is connected to the PF port of the multi-way valve through a one-way valve; the LS port of the priority valve is connected to the LS port of the multi-way valve; the multi-way valve controls the connection between the lifting cylinder and the tilting cylinder; the controller is electrically connected to the pump, the selection valve, the first solenoid valve, and the second solenoid valve. The hydraulic system of the present invention can realize automatic driving control and manual driving control, and can also have an energy-saving mode for automatic driving; when a failure occurs in the automatic driving, the manual driving mode is automatically started, thereby improving maintenance efficiency.

Description

Technical Field

[0001] The invention relates to an electric forklift hydraulic system, in particular to a forklift hydraulic control system capable of realizing automatic driving and manual driving. Background Art

[0002] It is a trend for electric counterbalanced forklifts to realize unmanned automatic driving, which can improve productivity. The hydraulic system of the existing manual driving mode is a traditional mechanical valve, which cannot use the electrical signal of the controller for proportional control. Considering the full switching of solenoid valves, the cost will increase too much. At the same time, if the hydraulic system fails, the automatic driving vehicle will not be able to move, which will reduce production efficiency. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a forklift hydraulic control system that can realize automatic driving and manual driving. On the basis of the automatic driving mode, the present invention can also retain the existing manual driving mode. When the automatic driving mode fails due to a fault, the whole vehicle automatically switches to the independent manual driving mode to ensure maintenance efficiency and production progress.

[0004] The present invention is achieved through the following technical solutions: a forklift hydraulic control system capable of realizing automatic driving and manual driving, comprising a pump, wherein the pump oil outlet is connected to a selection valve; the first oil circuit of the selection valve is connected to a multi-way valve, and the second oil circuit of the selection valve is connected to a priority valve; the priority valve oil outlet A is respectively connected to a first solenoid valve and a second solenoid valve; the first solenoid valve is connected to a lifting cylinder, and the second solenoid valve is connected to a tilting cylinder; the PF port of the priority valve is connected to the PF port of the multi-way valve through a one-way valve; the LS port of the priority valve is connected to the LS port of the multi-way valve; the multi-way valve controls the connection of the lifting cylinder and the tilting cylinder; and a controller is electrically connected to the pump, the selection valve, the first solenoid valve, and the second solenoid valve.

[0005] Furthermore, the second oil circuit of the selection valve is also connected to a second overflow valve, and the second overflow valve is connected to the oil tank.

[0006] The priority valve is connected to a first overflow valve, and the first overflow valve is connected to the oil tank.

[0007] The P3 port of the first solenoid valve is connected to the A port of the priority valve, the A3 port of the first solenoid valve is connected to the large chamber oil inlet of the lifting cylinder, the B3 port of the first solenoid valve is blocked with an oil plug, and the T3 port of the first solenoid valve is connected to the oil tank.

[0008] The P4 port of the second solenoid valve is connected to the A port of the priority valve, the A4 port of the second solenoid valve is connected to the large chamber oil inlet of the tilt cylinder, the B4 port of the second solenoid valve is connected to the small chamber oil inlet of the tilt cylinder, and the T4 port of the second solenoid valve is connected to the oil tank.

[0009] The P port of the multi-way valve is connected to the first oil circuit of the selection valve, the A1 port of the multi-way valve is connected to the large-cavity oil inlet of the lifting cylinder, the B1 port of the multi-way valve is blocked with an oil plug, the A2 port of the multi-way valve is connected to the large-cavity oil inlet of the tilt cylinder, the B2 port of the multi-way valve is connected to the small-cavity oil inlet of the tilt cylinder, and the T port of the multi-way valve is connected to the oil tank.

[0010] The PF port of the priority valve and the PF port of the multi-way valve are connected to the oil inlet of the steering system, and the LS port of the priority valve and the LS port of the multi-way valve are connected to the control oil port of the steering system.

[0011] The pump is connected to the pump motor via a spline transmission, and the controller is electrically connected to the pump motor.

[0012] The present invention realizes the integration of two hydraulic control modes of the electric forklift. When the hydraulic system of the automatic driving mode fails, the selection valve can automatically cut off the power and automatically switch to the manual driving hydraulic system. The driver can still operate the forklift normally to work, or drive to a maintenance point for fixed-point maintenance, thereby improving maintenance efficiency.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The hydraulic system can realize automatic driving control and manual driving control, and can also have an energy-saving mode for automatic driving;

[0015] 2. The entire hydraulic control system has significant cost advantages compared with high-end electro-hydraulic proportional valve hydraulic systems;

[0016] 3. Compared with simple manual driving, multiple electric forklifts can be operated unmanned at the same time, greatly improving production efficiency;

[0017] 4. When an automatic driving failure occurs, the manual driving mode is automatically started, which improves maintenance efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a working principle diagram of the present invention;

[0019] In the figure: 1. Pump; 2. Selection valve; 3. Priority valve; 4. First solenoid valve; 5. Second solenoid valve; 6. Lifting cylinder; 7. Tilt cylinder; 8. Multi-way valve; 9. Check valve; 10. First overflow valve; 11. Second overflow valve; 12. Pump motor; 13. Controller. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Combination Figure 1 As shown, a hydraulic control system for a forklift that can realize automatic driving and manual driving, the pump 1 is connected to the pump motor 12 through a spline transmission, the oil outlet of the pump 1 is connected to the oil inlet of the selection valve 2; the first oil circuit of the selection valve 2 is connected to the oil port P of the multi-way valve 8, and the second oil circuit of the selection valve 2 is connected to the oil port P of the priority valve 3; the second oil circuit of the selection valve 2 is also connected to a second overflow valve 11, and the second overflow valve 11 is connected to the oil tank, and the second overflow valve 11 ensures the normal operation of the working hydraulic system. The B port of the priority valve 3 is connected to the first overflow valve 10, and the first overflow valve 10 is connected to the oil tank. The oil outlet A of the priority valve 3 is connected to the first solenoid valve 4 and the second solenoid valve 5 respectively. The controller 13 is electrically connected to the pump motor 12, the selection valve 2, the first solenoid valve 4, and the second solenoid valve 5, D0 corresponds to the pump motor, D1 corresponds to the selection valve, D2 corresponds to the first solenoid valve, and D3 corresponds to the second solenoid valve.

[0022] Specific:

[0023] The P3 port of the first solenoid valve 4 is connected to the A port of the priority valve 3, the A3 port of the first solenoid valve 4 is connected to the large chamber oil inlet of the lifting cylinder 6, the B3 port of the first solenoid valve 4 is blocked with an oil plug, and the T3 port of the first solenoid valve 4 is connected to the oil tank;

[0024] The P4 port of the second solenoid valve 5 is connected to the A port of the priority valve 3, the A4 port of the second solenoid valve 5 is connected to the large chamber oil inlet of the tilt cylinder 7, the B4 port of the second solenoid valve 5 is connected to the small chamber oil inlet of the tilt cylinder 7, and the T4 port of the second solenoid valve 5 is connected to the oil tank;

[0025] The A1 port of the multi-way valve 8 is connected to the large-cavity oil inlet of the lifting cylinder 6, the B1 port of the multi-way valve 8 is blocked with an oil plug, the A2 port of the multi-way valve 8 is connected to the large-cavity oil inlet of the tilt cylinder 7, the B2 port of the multi-way valve 8 is connected to the small-cavity oil inlet of the tilt cylinder 7, and the T port of the multi-way valve 8 is connected to the oil tank;

[0026] The PF port of the priority valve 3 is connected to the PF port of the multi-way valve 8 through the one-way valve 9, and the LS port of the priority valve 3 is connected to the LS port of the multi-way valve 8. The PF port of the priority valve 3 and the PF port of the multi-way valve 8 are connected to the oil inlet of the steering system, and the LS port of the priority valve 3 and the LS port of the multi-way valve 8 are connected to the control oil port of the steering system.

[0027] The first overflow valve 10 ensures the working pressure of the steering system. The priority valve mainly controls the whole vehicle to perform priority steering. The one-way valve 9 performs one-way conduction control on the oil circuit of the steering system, thereby realizing the integration of two hydraulic control modes of the electric forklift. When steering, the pressure difference at both ends of the priority valve 3 controls the valve core of the priority valve to move left, so that more flow is used for the steering system through the PF port. When not steering, the LS port of the priority valve directly returns to the oil tank, and the valve core of the priority valve automatically moves right to the working hydraulic system position under the action of the throttle port through the PF port.

[0028] Working principle:

[0029] The outlet of the pump 1 passes through the selection valve 2 to select and switch between the automatic driving mode and the manual driving mode, and the circuit signal of the selection and switching is controlled by the controller 13.

[0030] The first solenoid valve 4 adopts an O-type function to control the lifting cylinder 6 of the electric forklift.

[0031] When the forklift is lifted, the controller 13 outputs control signals to the pump motor 12, the selector valve 2 and the first solenoid valve 4 respectively, the pump motor 12 drives the pump 1 to operate, the selector valve 2 switches to the automatic driving mode, and after the first solenoid valve 4 is energized, the valve core moves to the right, the oil circuit of the lifting action is connected, and the whole vehicle is lifted;

[0032] When the forklift fork needs to be lowered, the controller 13 outputs control signals to the pump motor 12, the selection valve 2 and the first solenoid valve 4 respectively, the pump motor 12 drives the pump 1 to operate, the selection valve 2 switches to the manual driving mode, and after the first solenoid valve 4 is energized, the valve core moves to the left, the lower chamber of the lifting cylinder 6 is connected to the return oil circuit, and the lifting cylinder 6 performs a descending action under the action of gravity, while the oil inlet is blocked. At this time, the controller 13 controls the pump motor 12 to operate at a low speed, and the selection valve 2 is powered off, and the main oil circuit returns oil through the multi-way valve 8; that is, when the fork is lowered, the pump 1 is unloaded through the multi-way valve 8.

[0033] The second solenoid valve 5 controls the tilt cylinder 7 to tilt forward or backward.

[0034] When tilting forward is required, the controller 13 outputs control signals to the pump motor 12, the selector valve 2 and the second solenoid valve 5 respectively, the pump motor 12 drives the pump 1 to operate, the selector valve 2 switches to the automatic driving mode, the second solenoid valve 5 is energized, the valve core moves right, and the hydraulic oil passes through the pump 1, the selector valve 2 and the second solenoid valve 5 to the tilt cylinder 7 to perform the tilting action, the tilt cylinder 7 large chamber enters the oil, and the small chamber returns the oil;

[0035] When tilting is required, the controller 13 outputs control signals to the pump motor 12, the selection valve 2 and the second solenoid valve 5 respectively, the pump motor 12 drives the pump 1 to operate, the selection valve 2 switches to the automatic driving mode, the second solenoid valve 5 is energized, the valve core moves to the left, and the hydraulic oil passes through the pump 1, the selection valve 2, and the second solenoid valve 5 to the tilt cylinder 7 to perform a tilting action, and the small chamber of the tilt cylinder 7 takes in oil, and the large chamber returns oil.

[0036] When the automatic driving mode is activated, there is no lifting, lowering, forward or backward tilting, or steering action; then the controller 13 will output a control signal to the selection valve 2 and the pump motor 12, and the selection valve 2 will automatically switch to the manual driving mode. The pump motor 12 will drive the pump 1 to operate at a low speed, and the pump 1 will unload through the multi-way valve 8 to reduce the heat generation of the hydraulic system, that is, the energy-saving mode.

[0037] The above solution can realize the integration of the two hydraulic control modes of the electric forklift. When the hydraulic system of the automatic driving mode fails, the selection valve can automatically cut off the power and automatically switch to the manual driving hydraulic system. The driver can still operate the forklift normally to work, or drive to the maintenance point for fixed-point maintenance, thereby improving maintenance efficiency.

[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A forklift hydraulic control system that can realize automatic driving and manual driving, It comprises a pump (1), wherein the oil outlet of the pump (1) is connected to a selection valve (2); a first oil circuit of the selection valve (2) is connected to a multi-way valve (8), and a second oil circuit of the selection valve (2) is connected to a priority valve (3); The oil outlet A of the priority valve (3) is respectively connected to a first solenoid valve (4) and a second solenoid valve (5); the first solenoid valve (4) is connected to a lifting cylinder (6), and the second solenoid valve (5) is connected to a tilting cylinder (7); the PF port of the priority valve (3) is connected to the PF port of the multi-way valve (8) via a one-way valve (9); the LS port of the priority valve (3) is connected to the LS port of the multi-way valve (8); The multi-way valve (8) controls the connection between the lifting cylinder (6) and the tilting cylinder (7); The controller (13) is electrically connected to the pump (1), the selection valve (2), the first solenoid valve (4), and the second solenoid valve (5).

2. The hydraulic control system for a forklift capable of automatic driving and manual driving according to claim 1, characterized in that: The second oil circuit of the selection valve (2) is also connected to a second overflow valve (11), and the second overflow valve (11) is connected to the oil tank.

3. The hydraulic control system for a forklift capable of automatic driving and manual driving according to claim 1, characterized in that: The priority valve (3) is connected to a first overflow valve (10), and the first overflow valve (10) is connected to an oil tank.

4. The hydraulic control system for a forklift capable of automatic driving and manual driving according to claim 1, characterized in that: The P3 port of the first solenoid valve (4) is connected to the A port of the priority valve (3), the A3 port of the first solenoid valve (4) is connected to the large chamber oil inlet of the lifting cylinder (6), the B3 port of the first solenoid valve (4) is blocked with an oil plug, and the T3 port of the first solenoid valve (4) is connected to the oil tank.

5. The forklift hydraulic control system capable of realizing automatic driving and manual driving according to claim 1, characterized in that: The P4 port of the second solenoid valve (5) is connected to the A port of the priority valve (3), the A4 port of the second solenoid valve (5) is connected to the large chamber oil inlet of the tilt cylinder (7), the B4 port of the second solenoid valve (5) is connected to the small chamber oil inlet of the tilt cylinder (7), and the T4 port of the second solenoid valve (5) is connected to the oil tank.

6. The hydraulic control system for a forklift capable of automatic driving and manual driving according to claim 1, characterized in that: The P port of the multi-way valve (8) is connected to the first oil circuit of the selection valve (2), the A1 port of the multi-way valve (8) is connected to the large-cavity oil inlet of the lifting cylinder (6), the B1 port of the multi-way valve (8) is blocked by an oil plug, the A2 port of the multi-way valve (8) is connected to the large-cavity oil inlet of the tilting cylinder (7), the B2 port of the multi-way valve (8) is connected to the small-cavity oil inlet of the tilting cylinder (7), and the T port of the multi-way valve (8) is connected to the oil tank.

7. The forklift hydraulic control system capable of realizing automatic driving and manual driving according to claim 6, characterized in that: The PF port of the priority valve (3) and the PF port of the multi-way valve (8) are connected to the oil inlet of the steering system, and the LS port of the priority valve (3) and the LS port of the multi-way valve (8) are connected to the control oil port of the steering system.

8. The forklift hydraulic control system capable of realizing automatic driving and manual driving according to claim 1, characterized in that: The pump (1) is connected to the pump motor (12) via a spline transmission, and the controller (13) is electrically connected to the pump motor (12).

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