Independent steering hydraulic system for multidirectional forklift

Abstract

The independent steering hydraulic system for the multidirectional forklift comprises a hydraulic pump assembly, a controller assembly, a control valve assembly and a steering oil cylinder assembly, the hydraulic pump assembly comprises an oil tank, a hydraulic pump and a motor which are sequentially communicated, an input port of the control valve assembly is connected with the hydraulic pump, and an output port of the control valve assembly is connected with the steering oil cylinder assembly. An output port of the control valve assembly is connected with the steering oil cylinder assembly; the controller assembly is connected with the motor and the control valve assembly, the controller assembly comprises a steering wheel, an encoder connected with the steering wheel, a programmable logic controller connected with the encoder and a motor controller connected with the programmable logic controller, and the motor controller controls starting, stopping and rotating speed of the motor. The steering wheel of the multidirectional forklift can be easily operated whether the multidirectional forklift is indoors or outdoors, so that the forklift can steer in a straight running mode or a side running mode and the like, and the oil cylinder can accurately stay at any position wanted by an operator.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of fork truck equipment, concretely relates to a kind of independent steering hydraulic system for multidirectional fork truck. BACKGROUND

[0002] At present, the steering system of multidirectional fork truck is not hydraulic pressure but pure electric steering, if pure electric steering is used, each steering wheel needs steering motor, steering controller and some related accessories, with high cost, and cannot well adapt to sandstone pavement, asphalt pavement and the like in field.Usually, to save cost, steering system and working system are integrated together if hydraulic pressure system is used, such as the steering system in patent CN202010543129.2, but doing so can make the control of system very complex, and working system and steering system simultaneously act, will conflict with each other, steering feel is poor, direction is heavy, cannot be well operated, especially in field, if through bad pavement, direction at this time is operated heavy, without road feel.Oil cylinder locking effect is not good, oil cylinder can independently stretch and retract due to leakage when driving, especially in straight-ahead state, oil cylinder can stretch out, deviate from the direction required by operator himself. SUMMARY

[0003] In view of all or part of the deficiencies of the prior art described above, the purpose of the utility model is to provide a kind of independent steering hydraulic system for multidirectional fork truck, multidirectional fork truck can be easily operated steering wheel whether in indoor or outdoor, make fork truck steer in straight-ahead or lateral mode, and oil cylinder can be accurately stayed at any position wanted by operator.

[0004] To achieve the above utility model purpose, the utility model provides the following technical scheme:

[0005] The utility model provides a kind of independent steering hydraulic system for multidirectional fork truck, including hydraulic pump assembly, controller assembly, control valve assembly and steering cylinder assembly, the hydraulic pump assembly includes oil tank, hydraulic pump and motor communicated sequentially, the input port of the control valve assembly is connected the hydraulic pump, the output port of the control valve assembly is connected the steering cylinder assembly;The controller assembly is connected with the motor and the control valve assembly, the controller assembly includes steering wheel, encoder connected with the steering wheel, programmable logic controller connected with the encoder, motor controller connected with the programmable logic controller, and the motor controller controls the start-stop and rotational speed of the motor.The prior art can use hydraulic steering gear, and the steering force is very large when steering, and it will conflict with the working system, and the working system and steering system will be simultaneously operated, which will cause the phenomenon of jam and heavy steering wheel.The utility model separates steering system and working system, does not use hydraulic steering gear additionally, and the steering system is controlled by separate power source, and the encoder is directly connected below the steering wheel, and the motor is controlled by programmable logic controller (PLC) instruction, so that the faster the rotational speed of the steering wheel is, the faster the rotational speed of the motor is, and the faster the rotational speed of the steering cylinder is, so that the following property of the steering system is better, and the problem of heavy steering wheel and difficult control can be solved by soft connection.

[0006] The steering cylinder assembly includes a first steering cylinder, a second steering cylinder and a third steering cylinder, the first steering cylinder has a first rod cavity and a first rodless cavity, the second steering cylinder has a second rod cavity and a second rodless cavity, and the third steering cylinder has a third rod cavity and a third rodless cavity, the second rodless cavity and the third rod cavity are connected, and the first rod cavity, the first rodless cavity, the second rod cavity and the third rodless cavity are connected with the control valve assembly.

[0007] The control valve assembly includes a first electromagnetic reversing valve, a second electromagnetic reversing valve and a third electromagnetic reversing valve, the A1 port of the first electromagnetic reversing valve is communicated with the first rodless cavity of the first steering cylinder, and the B1 port is communicated with the first rod cavity of the first steering cylinder, the A2 port of the second electromagnetic reversing valve is communicated with the second rod cavity of the second steering cylinder, and the B2 port is communicated with the third rodless cavity of the third steering cylinder, the third electromagnetic reversing valve is a two-position six-way electromagnetic valve, the P3 port is communicated with the hydraulic pump, the A3-1 port is communicated with the P1 port of the first electromagnetic reversing valve, the B3-1 port is communicated with the T1-1 port of the first electromagnetic reversing valve, the A3-2 port is communicated with the P2 port of the second electromagnetic reversing valve, the B3-2 port is communicated with the T2-1 port of the second electromagnetic reversing valve, and the T3 port is communicated with the oil tank.The first electromagnetic reversing valve, the second electromagnetic reversing valve and the third electromagnetic reversing valve are used to judge the direction of oil, and the two-position six-way electromagnetic valve can realize multiple functions simply, avoid multiple electromagnetic valves operation, reduce pipeline setting and save cost.

[0008] The control valve assembly further comprises a first balance valve and a second balance valve, the first balance valve is located on the communication pipeline between the first electromagnetic reversing valve and the first steering oil cylinder, and the second balance valve is located on the communication pipeline between the second electromagnetic reversing valve and the second steering oil cylinder and the third steering oil cylinder. The first balance valve and the second balance valve can keep the current position of the first steering oil cylinder, the second steering oil cylinder and the third steering oil cylinder without any leakage and action, and the second steering oil cylinder and the third steering oil cylinder can keep real-time synchronization. Compared with ordinary lock liquid valves, the locking effect is better. The balance valve is used to smoothly lock the oil cylinder and prevent the oil cylinder from leaking. If a hydraulic control check valve or a hydraulic lock is used, impact will be generated due to inertia when stopping.

[0009] The first electromagnetic reversing valve and the second electromagnetic reversing valve are two-position six-way electromagnetic valves, the first electromagnetic reversing valve has T1-2 port and T1-3 port as first return oil port and second return oil port respectively, the second electromagnetic reversing valve has T2-2 port and T2-3 port as third return oil port and fourth return oil port respectively, the first return oil port, the second return oil port, the third return oil port and the fourth return oil port are communicated and connected with the oil tank to form a first return oil passage. The first return oil port and the second return oil port are used for the return oil of the first balance valve communicated with the first electromagnetic reversing valve, and the third return oil port and the fourth return oil port are used for the return oil of the second balance valve communicated with the second electromagnetic reversing valve. The first balance valve and the second balance valve are easily subjected to back pressure between the first electromagnetic reversing valve and the second electromagnetic reversing valve to open the first balance valve and the second balance valve, which affects the oil of the steering oil cylinder to make it fluctuate. The return oil of the first balance valve and the second balance valve can make the first balance valve and the second balance valve have no back pressure and lock the steering oil cylinder firmly. For example, when the first steering oil cylinder and the second steering oil cylinder do not act, and the third steering oil cylinder acts, if the back pressure opens the second balance valve, the oil will move. Therefore, the first return oil passage is needed to return oil to the second balance valve. The first return oil passage is an independent return oil passage and does not mix with other valve assemblies for return oil, which can ensure the locking effect. If the return oil is mixed with other valves, the first balance valve or the second balance valve is easily opened by back pressure.

[0010] The control valve assembly further comprises a hydraulic control proportional reversing valve, the P4 port of the hydraulic control proportional reversing valve is communicated with the hydraulic pump, the A4 port is communicated with the P3 port of the third electromagnetic reversing valve, the B4 port is communicated with the T3 port of the third electromagnetic reversing valve, and the T4 port is communicated with the oil tank.

[0011] The control valve assembly further comprises a fourth electromagnetic reversing valve and a fifth electromagnetic reversing valve for controlling the hydraulic control proportional reversing valve; a first end of the fourth electromagnetic reversing valve is communicated with the hydraulic pump, and a second end thereof serves as a seventh oil return port; a first end of the fifth electromagnetic reversing valve is communicated with the hydraulic pump, and a second end thereof serves as a sixth oil return port; a T4 port of the hydraulic control proportional reversing valve serves as a seventh oil return port; the seventh oil return port, the sixth oil return port and the seventh oil return port are communicated and connected with the oil tank to form a second oil return passage. The ordinary electromagnetic proportional reversing valve controls the opening of the valve core by current, and impact may occur if the current control is not stable. The fourth electromagnetic reversing valve and the fifth electromagnetic reversing valve can be adjusted in proportion, and the large flow of the hydraulic control proportional reversing valve can be controlled by the small flow of the fourth electromagnetic reversing valve and the fifth electromagnetic reversing valve. The control by the two electromagnetic reversing valves can make the control of the hydraulic control proportional reversing valve more stable, smoother and more accurate.

[0012] The control valve assembly further comprises a shuttle valve and a load feedback valve; a first end of the shuttle valve is communicated with a P3 port of the third electromagnetic reversing valve; a second end of the shuttle valve is communicated with a T3 port of the third electromagnetic reversing valve; a third end of the shuttle valve is connected with the load feedback valve; and the load feedback valve is installed between the hydraulic pump and the hydraulic control proportional reversing valve. In all actions, the shuttle valve monitors the pressures of the rodless chamber and the rod chamber of the steering oil cylinder in real time, feeds back to the load feedback valve, automatically adjusts the size of the valve core to control the flow and pressure, ensures that the pressure drop into the main oil way remains constant and is not affected by the change of the load pressure, so that the steering action of the oil cylinder is more stable and no impact occurs. The hydraulic control proportional reversing valve, the fourth electromagnetic reversing valve, the fifth electromagnetic reversing valve, the shuttle valve and the load feedback valve serve as a group of control valves for controlling the flow of the front oil, and the flow of the hydraulic control proportional reversing valve can be controlled to a certain extent by controlling the rotating speed of the motor, and then adjusted by the load feedback valve, the fourth electromagnetic reversing valve and the fifth electromagnetic reversing valve. If the pressure fluctuates according to the monitoring of the shuttle valve on both ends of the steering oil cylinder, the load feedback valve can actively reduce the oil amount, so that the oil cylinder does not shake when extending and retracting, thereby making the steering more stable. The hydraulic pump is a gear pump, an oil outlet of the gear pump is provided with a first filter; the control valve assembly further comprises an overflow valve, a first end of the overflow valve is communicated with the hydraulic pump through the first filter, and a second end of the overflow valve is communicated with the oil tank. The overflow valve is an electromagnetic overflow valve, which can prevent impact, and delay may occur when the motor starts. When the working system stops, the motor may not have stopped working, and the hydraulic oil can directly return to the oil tank through the overflow valve. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical scheme in the specific embodiments of the utility model, the following will briefly introduce the drawings needed to be used in the embodiment description, obviously, the drawings described below are only some embodiments of the utility model, for the ordinary skilled in the art, on the premise of not creating labor, other drawings can also be obtained according to these drawings.

[0014] Figure 1 It is the connection schematic diagram of controller assembly in example 1.

[0015] Figure 2 It is the connection schematic diagram of hydraulic pump assembly, control valve assembly and steering oil cylinder assembly in example 1.

[0016] Figure 3 It is the schematic diagram of the first electromagnetic reversing valve in example 1.

[0017] Figure 4 It is the schematic diagram of the second electromagnetic reversing valve in example 1.

[0018] Figure 5 It is the schematic diagram of the third electromagnetic reversing valve in example 1.

[0019] Figure 6 It is the schematic diagram of the hydraulic control proportional reversing valve in example 1.

[0020] Figure 7 It is the schematic diagram of mode switching type in example 2.The drawing mark: 1-tank;2-hydraulic pump;3-motor;41-first filter;42-second filter;5-steering wheel;6-encoder;7-programmable logic controller;8-motor controller;9-first steering oil cylinder;10-second steering oil cylinder;11-third steering oil cylinder;12-excess flow valve;13-first electromagnetic reversing valve;14-second electromagnetic reversing valve;15-third electromagnetic reversing valve;16-fourth electromagnetic reversing valve;17-fifth electromagnetic reversing valve;18-hydraulic control proportional reversing valve;19-first balance valve;20-second balance valve;21-shuttle valve;22-load feedback valve;23-rear steering assembly;24-left front steering assembly;25-right front steering assembly;26-vehicle body. DETAILED DESCRIPTION

[0021] The technical scheme in the specific embodiments of the utility model will be described clearly and completely below, obviously, the described embodiments are only some embodiments of the utility model, not all the embodiments.Based on the embodiments in the utility model, all other embodiments obtained by the ordinary skilled in the art without creating labor belong to the scope of protection of the utility model.

[0022] It should be noted that in order to more specifically describe the technical solutions, the steps described in the following embodiments do not strictly and practically correspond to the steps described in the utility model content part.

[0023] Embodiment 1

[0024] A multi-directional forklift independent steering hydraulic system, referring to Figure 1 and Figure 2 , comprising a hydraulic pump assembly, a controller assembly, a control valve assembly and a steering cylinder assembly.

[0025] The hydraulic pump assembly comprises an oil tank 1, a hydraulic pump 2 and a motor 3 connected in sequence, the hydraulic pump 2 is a gear pump controlled by a set of independent motor 3. The oil outlet of the gear pump is provided with a first filter 41, and the hydraulic pump 2 is connected with the oil tank 1 through a second filter 42; the oil liquid reaches the hydraulic pump 2 from the oil tank 1 through the second filter 42, and enters the first filter 41 under the action of the motor 3. The input port of the control valve assembly is connected with the first filter 41 behind the hydraulic pump 2, and the output port of the control valve assembly is connected with the steering cylinder assembly.

[0026] The controller assembly is connected with the motor 3, the controller assembly is connected with the control valve assembly, the controller assembly comprises a steering wheel 5, an encoder 6 connected with the steering wheel 5, a programmable logic controller 7 connected with the encoder 6, and a motor controller 8 connected with the programmable logic controller 7, the motor controller 8 controls the start-stop and rotating speed of the motor 3. The steering wheel 5 is directly connected with the encoder 6, the encoder 6 is rotated to give a signal by the steering wheel 5, the signal of the encoder 6 is transmitted to the programmable logic controller 7, and the programmable logic controller 7 controls all actions according to the received signal of the encoder 6. The programmable logic controller 7 gives instructions to the motor controller 8 to control the start-stop and rotating speed of the motor 3. At the same time, the programmable logic controller 7 controls the action of various valves to realize the extension and retraction of the oil cylinder, so as to realize the steering of the steering wheel, so as to realize the steering and mode switching. The whole hydraulic system is simple and can realize the steering of the oil cylinder well. The instruction of mode switching comes from the direction switch or the original rotary switch, and at this time, the steering wheel is in the invalid state.

[0027] The steering cylinder assembly includes a first steering cylinder 9, a second steering cylinder 10 and a third steering cylinder 11, the first steering cylinder 9 has a first rod cavity and a first rodless cavity, the second steering cylinder 10 has a second rod cavity and a second rodless cavity, the third steering cylinder 11 has a third rod cavity and a third rodless cavity, the second rodless cavity and the third rod cavity are connected, and the first rod cavity, the first rodless cavity, the second rod cavity and the third rodless cavity are connected with the control valve assembly. In this embodiment, the first steering cylinder 9 is a rear steering cylinder, which controls the steering of the rear wheels; the second steering cylinder 10 is a left front steering cylinder, which controls the steering of the left front wheels; and the third steering cylinder 11 is a right front steering cylinder, which controls the steering of the right front wheels.

[0028] The control valve assembly includes a relief valve 12, a first electromagnetic directional valve 13, a second electromagnetic directional valve 14, a third electromagnetic directional valve 15, a fourth electromagnetic directional valve 16, a fifth electromagnetic directional valve 17, a hydraulic control proportional directional valve 18, a first balance valve 19, a second balance valve 20, a shuttle valve 21 and a load feedback valve 22. The first end of the relief valve 12 is communicated with the hydraulic pump 2 through a first filter 41, and the second end of the relief valve 12 is communicated with the oil tank 1.

[0029] Referring to Figures 3 to 6 , the first electromagnetic directional valve 13 and the second electromagnetic directional valve 14 are two-position six-way electromagnetic valves, the A1 port of the first electromagnetic directional valve 13 is communicated with the first rodless cavity of the first steering cylinder 9, and the B1 port is communicated with the first rod cavity of the first steering cylinder 9; the A2 port of the second electromagnetic directional valve 14 is communicated with the second rod cavity of the second steering cylinder 10, and the B2 port is communicated with the third rodless cavity of the third steering cylinder 11. The first balance valve 19 is located on the communication pipeline of the first electromagnetic directional valve 13 and the first steering cylinder 9, and the second balance valve 20 is located on the communication pipeline of the second electromagnetic directional valve 14 and the second steering cylinder 10 and the third steering cylinder 11. The first electromagnetic directional valve 13 has a T1-2 port and a T1-3 port as a first return port and a second return port respectively, and the second electromagnetic directional valve 14 has a T2-2 port and a T2-3 port as a third return port and a fourth return port respectively, the first return port, the second return port, the third return port and the fourth return port are communicated and connected with the oil tank 1, forming a first return passage.

[0030] The third electromagnetic reversing valve 15 is a two-position six-way electromagnetic valve, the P3 port is communicated with the A4 port of the hydraulic control proportional reversing valve 18 and then indirectly communicated with the hydraulic pump 2, the A3-1 port is communicated with the P1 port of the first electromagnetic reversing valve 13, the B3-1 port is communicated with the T1-1 port of the first electromagnetic reversing valve 13, the A3-2 port is communicated with the P2 port of the second electromagnetic reversing valve 14, the B3-2 port is communicated with the T2-1 port of the second electromagnetic reversing valve 14, and the T3 port is communicated with the B4 port of the hydraulic control proportional reversing valve 18 and then indirectly communicated with the oil tank 1. The hydraulic control proportional reversing valve 18 is a three-position four-way hydraulic control proportional valve with Y type function, the P4 port is communicated with the load feedback valve 22 and then indirectly communicated with the hydraulic pump 2, the A4 port is communicated with the P3 port of the third electromagnetic reversing valve 15, the B4 port is communicated with the T3 port of the third electromagnetic reversing valve 15, and the T4 port is communicated with the oil tank 1. The fourth electromagnetic reversing valve 16 and the fifth electromagnetic reversing valve 17 are used for controlling the hydraulic control proportional reversing valve 18, the first end of the fourth electromagnetic reversing valve 16 is communicated with the hydraulic pump 2, the second end is a seventh return port, and the control port is connected with the hydraulic control proportional reversing valve 18; the first end of the fifth electromagnetic reversing valve 17 is communicated with the hydraulic pump 2, the second end is a sixth return port, and the control port is connected with the hydraulic control proportional reversing valve 18. The T4 port of the hydraulic control proportional reversing valve 18 is a seventh return port, the seventh return port, the sixth return port and the seventh return port are communicated and connected with the oil tank 1, and a second return passage is formed.

[0031] The control valve assembly further comprises a shuttle valve 21 and a load feedback valve 22, the first end of the shuttle valve 21 is communicated with the P3 port of the third electromagnetic reversing valve 15, the second end of the shuttle valve 21 is communicated with the T3 port of the third electromagnetic reversing valve 15, the third end (a control oil port) of the shuttle valve 21 is connected with the load feedback valve 22, and the load feedback valve 22 is installed between the hydraulic pump 2 and the hydraulic control proportional reversing valve 18.

[0032] Embodiment 2

[0033] The utility model further provides a kind of independent steering control method for multidirectional fork truck, refer to Figures 1 to 7 , comprising:

[0034] S1, mode switching: mode switching switch signal is sent to programmable logic controller 7, programmable logic controller 7 issues instruction to motor controller 8, and motor controller 8 controls the motor 3 connected with the hydraulic pump 2 to reach certain rotating speed;Programmable logic controller 7 controls the opening and closing of control valve assembly connected with the hydraulic pump 2, so that the steering cylinder assembly connected with the control valve assembly switches steering wheel into straight or side mode.

[0035] S2, steering control: operating the steering wheel 5, the encoder 6 connected with the steering wheel 5 generates a steering signal, the steering signal obtained by the encoder 6 is sent to the programmable logic controller 7, the programmable logic controller 7 sends an instruction to the motor controller 8, the motor controller 8 controls the start-stop and rotation speed of the motor 3 according to the rotation speed of the steering wheel 5.

[0036] Specifically comprising the following steps:

[0037] In the initial state, if the steering wheel 5 does not rotate, the encoder 6 does not generate any signal, at this time the programmable logic controller 7 has no instruction to the motor controller 8 and the control valve assembly, at this time the motor 3 does not act, the first steering cylinder 9, the second steering cylinder 10 and the third steering cylinder 11 remain in the existing position.

[0038] When the mode switching action is performed, the direction switch is turned to any direction (for example, forward, backward, left or right) or the original turning-on switch is pressed. At this time, the steering wheel 5 is invalid (controlled by the programmable logic controller 7), the switch signal is directly sent to the programmable logic controller 7, and the programmable logic controller 7 gives an instruction to the motor controller 8 to make the motor 3 reach a certain rotation speed.

[0039] Reference Figure 2 Figure 2 For the case that the first electromagnetic reversing valve 13, the second electromagnetic reversing valve 14 and the third electromagnetic reversing valve 15 are all de-energized, only the structure is shown, and the energization and de-energization of the electromagnetic valves are not limited. Through the programmable logic controller 7, the overflow valve 12 is energized, then the fourth electromagnetic reversing valve 16 or the fifth electromagnetic reversing valve 17 is energized, and the first electromagnetic reversing valve 13 is energized. At this time, the third electromagnetic reversing valve 15 and the second electromagnetic reversing valve 14 are in de-energized state, when the third electromagnetic reversing valve 15 is de-energized, it is communicated with the first electromagnetic reversing valve 13 (in other cases, if the third electromagnetic reversing valve 15 is energized, it is communicated with the second electromagnetic reversing valve 14). At this time, the second electromagnetic reversing valve 14 is de-energized, therefore, the T2-2 and T2-3 ports of the second electromagnetic reversing valve 14 can return oil through the first return oil passage (refer to Figure 4 ). The oil flows to the third electromagnetic reversing valve 15 through the hydraulic control proportional reversing valve 18, to the first electromagnetic reversing valve 13 through the third electromagnetic reversing valve 15, to the first balance valve 19 through the first electromagnetic reversing valve 13, to the first steering cylinder 9 from the first balance valve 19, and the first steering cylinder 9 acts to make the rear wheel assembly (rear steering assembly 23) connected with the first steering cylinder 9 become a straight or side mode, and then the fourth electromagnetic reversing valve 16, the fifth electromagnetic reversing valve 17 and the first electromagnetic reversing valve 13 are de-energized.

[0040] ​The third electromagnetic reversing valve 15 and the second electromagnetic reversing valve 14 are powered by the programmable logic controller 7, and the fourth electromagnetic reversing valve 16 or the fifth electromagnetic reversing valve 17 is powered. At this time, the first electromagnetic reversing valve 13 is de-energized, and therefore, the T1-2 and T1-3 ports of the first electromagnetic reversing valve 13 can return oil through the first oil return passage (refer to Figure 3 ). The oil flows through the hydraulic control proportional reversing valve 18 to the third electromagnetic reversing valve 15, from the third electromagnetic reversing valve 15 to the second electromagnetic reversing valve 14, from the second electromagnetic reversing valve 14 to the second balance valve 20, from the second balance valve 20 to the second steering oil cylinder 10 and the third steering oil cylinder 11, and the second steering oil cylinder 10 and the third steering oil cylinder 11 act simultaneously to make the front wheel assembly (including the left front steering assembly 24 corresponding to the second steering oil cylinder 10 and the right front steering assembly 25 corresponding to the third steering oil cylinder 11) into a straight or side mode, and the mode switching is completed. The vehicle body 26 is composed of the first steering oil cylinder 9, the second steering oil cylinder 10, the third steering oil cylinder 11, the rear steering assembly 23, the left front steering assembly 24, and the right front steering assembly 25.

[0041] After the mode switching is completed, all the electromagnetic valves in the control valve assembly are in a de-energized state, and at this time, the motor 3 is stopped. If the steering wheel 5 is operated, the motor 3 starts to rotate at a certain speed, and the corresponding electromagnetic valves are powered to make the corresponding steering oil cylinders act (refer to the electromagnetic valve control and steering oil cylinder action process in the above mode switching process, which will not be repeated here). The faster the steering wheel 5 rotates, the faster the motor 3 rotates. The mode switching is completed before the steering control, which makes the steering wheel 5 easier and more accurate to operate. The steering hydraulic system provided by the utility model is light and easy to steer, can make the oil cylinder keep in an accurate position to realize locking, optimizes the whole steering system, makes the steering system more accurate and light, and does not conflict with the working system. The above embodiments are only used to help understand the method and core idea of the utility model. It should be pointed out that for ordinary skilled persons in the technical field, some improvements and modifications can be made to the utility model without departing from the principles of the utility model, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

Claims

1. An independent steering hydraulic system for a multi-directional forklift, characterized in that, The system includes a hydraulic pump assembly, a controller assembly, a control valve assembly, and a steering cylinder assembly. The hydraulic pump assembly includes an oil tank (1), a hydraulic pump (2), and a motor (3) connected in sequence. The input port of the control valve assembly is connected to the hydraulic pump (2), and the output port of the control valve assembly is connected to the steering cylinder assembly. The controller assembly is connected to the motor (3) and the control valve assembly. The controller assembly includes a steering wheel (5), an encoder (6) connected to the steering wheel (5), a programmable logic controller (7) connected to the encoder (6), and a motor controller (8) connected to the programmable logic controller (7). The motor controller (8) controls the start, stop, and speed of the motor (3).

2. The independent steering hydraulic system for a multi-directional forklift according to claim 1, characterized in that, The steering cylinder assembly includes a first steering cylinder (9), a second steering cylinder (10), and a third steering cylinder (11). The first steering cylinder (9) has a first rod chamber and a first rodless chamber. The second steering cylinder (10) has a second rod chamber and a second rodless chamber. The third steering cylinder (11) has a third rod chamber and a third rodless chamber. The second rodless chamber and the third rod chamber are connected. The first rod chamber, the first rodless chamber, the second rod chamber, and the third rodless chamber are all connected to the control valve assembly.

3. The independent steering hydraulic system for a multi-directional forklift according to claim 2, characterized in that, The control valve assembly includes a first solenoid directional valve (13), a second solenoid directional valve (14), and a third solenoid directional valve (15). The A1 port of the first solenoid directional valve (13) is connected to the first rodless chamber of the first steering cylinder (9), and its B1 port is connected to the first rod chamber of the first steering cylinder (9). The A2 port of the second solenoid directional valve (14) is connected to the second rod chamber of the second steering cylinder (10), and its B2 port is connected to the third rod chamber of the third steering cylinder (11). The rodless chamber is connected; the third electromagnetic directional valve (15) is a two-position six-way electromagnetic valve, with port P3 connected to the hydraulic pump (2), port A3-1 connected to port P1 of the first electromagnetic directional valve (13), port B3-1 connected to port T1-1 of the first electromagnetic directional valve (13), port A3-2 connected to port P2 of the second electromagnetic directional valve (14), port B3-2 connected to port T2-1 of the second electromagnetic directional valve (14), and port T3 connected to the oil tank (1).

4. The independent steering hydraulic system for a multi-directional forklift according to claim 3, characterized in that, The control valve assembly further includes a first balance valve (19) and a second balance valve (20). The first balance valve (19) is located on the connecting pipeline between the first solenoid directional valve (13) and the first steering cylinder (9). The second balance valve (20) is located on the connecting pipeline between the second solenoid directional valve (14) and the second steering cylinder (10) and the third steering cylinder (11).

5. The independent steering hydraulic system for a multi-directional forklift according to claim 4, characterized in that, The first electromagnetic directional valve (13) and the second electromagnetic directional valve (14) are two-position six-way electromagnetic valves. The first electromagnetic directional valve (13) has ports T1-2 and T1-3 as the first return oil port and the second return oil port, respectively. The second electromagnetic directional valve (14) has ports T2-2 and T2-3 as the third return oil port and the fourth return oil port, respectively. The first return oil port, the second return oil port, the third return oil port and the fourth return oil port are connected and connected to the oil tank (1) to form the first return oil passage.

6. The independent steering hydraulic system for a multi-directional forklift according to claim 3, characterized in that, The control valve assembly also includes a hydraulic proportional directional valve (18), the P4 port of which is connected to the hydraulic pump (2), the A4 port of which is connected to the P3 port of the third electromagnetic directional valve (15), the B4 port of which is connected to the T3 port of the third electromagnetic directional valve (15), and the T4 port of which is connected to the oil tank (1).

7. The independent steering hydraulic system for a multi-directional forklift according to claim 6, characterized in that, The control valve assembly also includes a fourth solenoid directional valve (16) and a fifth solenoid directional valve (17) for controlling the hydraulic proportional directional valve (18); the first end of the fourth solenoid directional valve (16) is connected to the hydraulic pump (2), and the second end serves as the fifth return port; the first end of the fifth solenoid directional valve (17) is connected to the hydraulic pump (2), and the second end serves as the sixth return port; the T4 port of the hydraulic proportional directional valve (18) serves as the seventh return port, and the fifth, sixth, and seventh return ports are connected and connected to the oil tank (1) to form a second return passage.

8. The independent steering hydraulic system for a multi-directional forklift according to claim 6, characterized in that, The control valve assembly also includes a shuttle valve (21) and a load feedback valve (22). The first end of the shuttle valve (21) is connected to the P3 port of the third solenoid directional valve (15), the second end of the shuttle valve (21) is connected to the T3 port of the third solenoid directional valve (15), and the third end of the shuttle valve (21) is connected to the load feedback valve (22). The load feedback valve (22) is installed between the hydraulic pump (2) and the hydraulic proportional directional valve (18).

9. The independent steering hydraulic system for a multi-directional forklift according to claim 6, characterized in that, The hydraulic pump (2) is a gear pump, and the oil outlet of the gear pump is provided with a first filter (41); the control valve assembly also includes an overflow valve (12), the first end of the overflow valve (12) is connected to the hydraulic pump (2) through the first filter (41), and the second end of the overflow valve (12) is connected to the oil tank (1).

Images