CN111959604A - Multi-mode steering system - Google Patents

Abstract

A multi-mode steering system, the oil outlet of the hydraulic pump is connected to the P port of the priority valve, the CF port and the LS port of the priority valve are respectively connected to the P port and the LS port of the hydraulic steering gear; the EF port of the priority valve passes through the third port. The reversing valve is connected with the accumulator; the A port of the steering gear is respectively connected with the A port of the first differential pressure reducing valve and the A port of the fifth reversing valve, and its B port is respectively connected with the second fixed differential pressure reducing valve. Port A is connected to port A of the fourth reversing valve; port B of the fourth reversing valve, port B of the fifth reversing valve and pressure detection device are all connected to the accumulator; the first and second fixed differential pressure reduction The B port of the valve is connected with the P port of the first and second reversing valves respectively; the T ports of the first and second reversing valves are interconnected; the first reversing valve is connected to the front wheel through the first hydraulic control check valve group. The connection of the steering hydraulic cylinder; the second reversing valve is connected with the rear wheel steering hydraulic cylinder through the second hydraulic control one-way valve group. The system adopts hydraulic transmission mode, its steering mode is flexible, it is easy to turn and turn around, and at the same time, its operation process is convenient.

Description

A multi-mode steering system

technical field

The invention relates to the technical field of agricultural planting machinery, in particular to a multi-mode steering system.

Background technique

With the continuous advancement of agricultural modernization, agricultural production has developed from the traditional extensive type to the refined and intelligent direction. Most of the existing agricultural machinery adopts the method of front wheel steering, and some models adopt four-wheel steering. However, due to the large volume of the whole vehicle of agricultural machinery and the high center of gravity, the mobility of large and medium-sized agricultural machinery in the process of changing rows, U-turns and transitions is poor. At the same time, due to the relatively small area of farmland in my country, the steering range of agricultural machinery operations is limited, which puts forward more stringent requirements for the maneuverability of agricultural machinery steering. Therefore, research on multi-mode steering systems suitable for agricultural machinery is urgently needed.

SUMMARY OF THE INVENTION

Aiming at the problems existing in the above-mentioned prior art, the present invention provides a multi-mode steering system. The system adopts a hydraulic transmission mode, the steering mode is flexible, the turning is easy, and the damage to the seedling bed is small during the steering process. At the same time, its operation process convenient.

In order to achieve the above object, the present invention provides a multi-mode steering system, which includes a hydraulic pump, a fuel tank, a priority valve, a hydraulic steering gear, a relief valve, a third reversing valve, a first differential pressure reducing valve, and a fifth reversing valve. Valve, second fixed differential pressure reducing valve, fourth reversing valve, pressure detection device, front wheel steering hydraulic cylinder, first reversing valve, second reversing valve, first hydraulic control check valve group, first shuttle valve, second hydraulic control check valve group, rear wheel steering hydraulic cylinder and second shuttle valve;

The oil inlet and oil outlet of the hydraulic pump are respectively connected with the oil tank and the P port of the priority valve, and the oil outlet of the hydraulic pump is also connected with the oil tank through a safety valve; the CF port and the LS port of the priority valve are respectively connected with the hydraulic pressure. The P port and LS port of the steering gear are connected, the P port of the priority valve is connected to the CF port of the priority valve through the relief valve; the EF port of the priority valve is connected to the A port of the third reversing valve; the A port of the steering gear is respectively connected with Port A of the first differential pressure reducing valve is connected to port A of the fifth reversing valve; port B of the steering gear is respectively connected to port A of the second differential pressure reducing valve and port A of the fourth reversing valve; The B port of the three reversing valve, the B port of the fourth reversing valve, the B port of the fifth reversing valve and the pressure detection device are all connected to the accumulator;

The B port of the first constant differential pressure reducing valve and the B port of the second constant differential pressure reducing valve are respectively connected to the P port of the first reversing valve and the P port of the second reversing valve; the T port of the first reversing valve It is connected with the T port of the second reversing valve; the A port and B port of the first reversing valve are respectively connected with the A1 port and A2 port of the first hydraulic control check valve group, and the B1 port of the first hydraulic control check valve group Port and port B2 are respectively connected with port A and port B of the front wheel steering hydraulic cylinder; port A and port B of the first shuttle valve are respectively connected with port A and port B of the first reversing valve, and port C of the first shuttle valve The port is connected to the X port of the first differential pressure reducing valve; the A port and B port of the second reversing valve are respectively connected to the A1 port and A2 port of the second hydraulic control check valve group, and the second hydraulic control check valve The B1 port and B2 port of the group are respectively connected with the A port and B port of the rear wheel steering hydraulic cylinder; the A port and B port of the second shuttle valve are respectively connected with the A port and the B port of the second reversing valve. The C port of the valve is connected to the X port of the second differential pressure reducing valve;

The front wheel steering hydraulic cylinder and the rear wheel steering hydraulic cylinder are both double piston rod double acting symmetrical hydraulic cylinders.

Also includes controllers and control boxes;

The front wheel steering hydraulic cylinder and the rear wheel steering hydraulic cylinder are respectively connected with wire-pull displacement sensors A and B; the wire-pull displacement sensors A and B are respectively used to obtain the travel signal A of the front wheel steering hydraulic cylinder and the rear wheel steering in real time. The stroke signal B of the hydraulic cylinder is sent to the controller in real time;

The pressure detection device is used to collect the pressure signal of the accumulator in real time and send it to the controller in real time;

The control box is provided with at least a front-wheel steering mode button, a rear-wheel steering mode button and a four-wheel steering mode button, which are respectively used to send the front-wheel steering mode signal, the rear-wheel steering mode signal and the four-wheel steering mode button to the controller according to the control of the operator. Four-wheel steering mode signal;

The controller is respectively connected with the wire-pull displacement sensor A, the wire-pull displacement sensor B, the pressure detection device, the first reversing valve, the second reversing valve, the third reversing valve, the fourth reversing valve, and the fifth reversing valve. The valve is connected to the control box; it is used to obtain stroke information A and stroke information B according to the received stroke signals A and B; it is used to obtain the pressure value according to the received pressure signal, and when the pressure value is less than the set pressure value, control the third The reversing valve is energized, the fourth reversing valve is de-energized, and the fifth reversing valve is de-energized. When the pressure value is greater than or equal to the set pressure value, the third reversing valve is controlled to be de-energized; it is used to receive the front wheel steering mode When the signal is turned on, control the first reversing valve to work in the upper or lower position, and control the second reversing valve not to energize, so as to realize the steering action only through the front wheel; it is used to control the first steering mode signal when receiving the rear wheel steering mode signal. The second reversing valve is energized and works in the upper or lower position, and controls the first reversing valve not to be energized, so as to realize the steering action only through the front wheels; it is used to control the first reversing valve at the same time when receiving the four-wheel steering mode signal It works in the upper position when it is energized with the second reversing valve at the same time, or controls the first reversing valve and the second reversing valve at the same time and works in the lower position, and receives the front wheel steering mode signal within the set time before When receiving the four-wheel steering mode signal, control the first reversing valve to de-energize, the third reversing valve to de-energize, the fifth reversing valve to de-energize, the fourth reversing valve to energize, and the second reversing valve to be energized; When the rear wheel steering mode signal is received first and then the four-wheel steering mode signal is received within the set time, the second reversing valve is de-energized, the third reversing valve is de-energized, the fifth reversing valve is energized, and the fourth reversing valve is energized. The valve is de-energized, the first reversing valve is energized, and according to the received travel information B and travel information A, the front wheel steering hydraulic cylinder and the rear wheel steering hydraulic cylinder are kept synchronized, so as to realize the four-wheel steering action. .

The first hydraulic control check valve group is composed of a first hydraulic control check valve and a second hydraulic control check valve, and the oil inlet and the oil outlet of the first hydraulic control check valve are respectively connected to the first hydraulic control check valve. Port A and port B of the valve group, the oil inlet and oil outlet of the second hydraulic control check valve are respectively connected to the A port and B port of the first hydraulic control check valve group, and the first hydraulic control check valve The hydraulic control port and the hydraulic control port of the second hydraulic control check valve are respectively connected with the oil inlet of the second hydraulic control check valve and the oil inlet of the first hydraulic control check valve;

The second hydraulic control check valve group is composed of a third hydraulic control check valve and a fourth hydraulic control check valve. The oil inlet and the oil outlet of the third hydraulic control check valve are respectively connected to the second hydraulic control check valve. Port A and port B of the valve group, the oil inlet and oil outlet of the fourth hydraulic control check valve are respectively connected to the A port and B port of the second hydraulic control check valve group, and the third hydraulic control check valve The hydraulic control port and the hydraulic control port of the fourth hydraulic control check valve are respectively connected with the oil inlet of the fourth hydraulic control check valve and the oil inlet of the third hydraulic control check valve.

Further, in order to effectively filter the oil entering the system, the hydraulic pump is connected to the oil tank through a filter.

As a preference, the controller is a PLC controller.

As a preference, the third reversing valve, the fourth reversing valve and the fifth reversing valve are all two-position two-way electromagnetic reversing valves; the third reversing valve works in the left position after being energized, and is de-energized After working in the right position, when it works in the right position, the oil circuit between the A port and the B port is disconnected, and when it works in the left position, the oil circuit between the A port and the B port is connected; the fourth change When the valve is energized, it works in the left position, and when it is de-energized, it works in the right position. When it works in the left position, the oil circuit between the A port and the B port is connected. When it works in the right position, the A port and the B port are connected. The oil circuit between the ports is disconnected; the fifth reversing valve works in the lower position after being energized, and works in the upper position when the power is lost. When it works in the lower position, the oil circuit between the A port and the B port is connected, and it works in the When in the upper position, the oil circuit between the A port and the B port is disconnected.

As a preference, the first reversing valve is a three-position four-way electromagnetic reversing valve. When it is powered on and works in the upper position, the oil circuit between the P port and the A port is connected, and the T port and the B port are connected. The oil circuit between them is connected; when the power is in the neutral position, the P port and the T port are connected with each other, and the A port and the B port are cut off with each other; when the power is in the lower position, the P port and the B port are connected to each other. The oil circuit is connected, and the oil circuit between the T port and the A port is connected; the second reversing valve is a three-position four-way electromagnetic reversing valve. The oil circuit between the T port and the A port is connected; when the power failure is in the neutral position, the P port and the T port are connected with each other, and the A port and the B port are cut off with each other; when the power is in the upper position , the oil circuit between the P port and the A port is connected, and the oil circuit between the T port and the B port is connected.

In the present invention, the priority valve is a load-sensitive type, which can automatically adjust the flow according to the system requirements. For example, when the steering wheel is turned rapidly, the flow rate is large, otherwise, the flow rate is small; the setting of the priority valve can be used with the load-sensitive hydraulic steering gear, The LS oil port of the priority valve can obtain the working pressure of the steering system in real time, and then can first ensure the flow requirements of the steering oil circuit of the hydraulic steering gear, so that the system oil can be preferentially supplied to the front wheel steering circuit to ensure the sensitivity of steering. The fixed differential pressure reducing valve is used in conjunction with the shuttle valve to achieve pressure compensation, and the shuttle valve introduces the pressure of the high-pressure oil circuit into the X port (spring cavity side) of the fixed differential pressure reducing valve, ensuring the first reversing valve and the second reversing valve. The flow of the valve is not affected by the size of the load, but is only related to its opening, which further improves the control accuracy of the system. Through the setting of the controller and the control box, it is easy to realize the convenient switching between the front wheel steering mode, the rear wheel steering mode and the four-wheel steering mode, which further improves the flexibility of steering; at the same time, the EF oil port of the priority valve will remove the excess flow. It can charge the accumulator, improve the efficiency of the system, and avoid the occurrence of oil overflow and heating; through the setting of the controller and the control box, the connection timing of the accumulator can be reasonably controlled, so that the The combination of various steering modes can be realized under the premise of only using one hydraulic pump and steering gear; at the same time, it is also convenient to control the on-off of the reversing valve according to the displacement information of the steering hydraulic cylinder, so that the system can automatically adjust the steering state , and can make the steering state conform to the Ackerman steering principle; the setting of the hydraulic control check valve group can precisely lock the position of the hydraulic cylinder, and the hydraulic cylinder will not be displaced due to external loads. The system adopts hydraulic transmission mode, its steering mode is flexible, it is easy to turn and turn around, and the damage to the seedling bed is small during the steering process, and at the same time, its operation process is convenient.

Description of drawings

Fig. 1 is the hydraulic principle diagram of the present invention;

Fig. 2 is the schematic diagram of front wheel steering in the present invention;

Fig. 3 is the schematic diagram of rear wheel steering in the present invention;

FIG. 4 is a schematic diagram of four-wheel steering in the present invention.

In the picture: 1. Fuel tank, 2. Filter, 3. Hydraulic pump, 4. Safety valve, 5. Relief valve, 6. Priority valve, 7. Steering valve, 8. Metering motor, 9. First differential reduction Pressure valve, 10, first reversing valve, 11, first shuttle valve, 12, first hydraulic control check valve group, 13, front wheel steering hydraulic cylinder, 14, hydraulic steering gear, 15, fifth reversing valve , 16, the second fixed differential pressure reducing valve, 17, the second reversing valve, 18, the second shuttle valve, 19, the second hydraulic control check valve group, 20, the rear wheel steering hydraulic cylinder, 21, the accumulator , 22, the third reversing valve, 23, the pressure detection device, 24, the fourth reversing valve.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in FIGS. 1 to 4 , the present invention provides a multi-mode steering system, including a hydraulic pump 3 , a fuel tank 1 , a priority valve 6 , a hydraulic steering gear 14 , a relief valve 5 , a third reversing valve 22 , a first The fixed differential pressure reducing valve 9, the fifth switching valve 15, the second fixed differential pressure reducing valve 16, the fourth switching valve 24, the pressure detection device 23, the first switching valve 10, the second switching valve 17, the A hydraulically controlled check valve group 12 , a front wheel steering hydraulic cylinder 13 , a first shuttle valve 11 , a second hydraulically controlled check valve group 19 , a rear wheel steering hydraulic cylinder 20 and a second shuttle valve 18 ;

The oil inlet and oil outlet of the hydraulic pump 3 are respectively connected to the oil tank 1 and the P port of the priority valve 6, and the oil outlet of the hydraulic pump 3 is also connected to the oil tank 1 through the safety valve 4; the CF of the priority valve 6 is connected. The port and the LS port are respectively connected with the P port and the LS port of the hydraulic steering gear 14. The P port of the priority valve 6 is connected to the CF port of the priority valve 6 through the relief valve 5; the EF port of the priority valve 6 is connected to the third reversing valve. The A port of 22 is connected; the A port of the steering gear 14 is respectively connected with the A port of the first differential pressure reducing valve 9 and the A port of the fifth reversing valve 15; the B port of the steering gear 14 is respectively connected with the second differential pressure reducing valve. The A port of the pressure valve 16 is connected to the A port of the fourth reversing valve 24; the B port of the third reversing valve 22, the B port of the fourth reversing valve 24, the B port of the fifth reversing valve 15 and the pressure detection The devices 23 are all connected to the accumulator 21;

The B port of the first differential pressure reducing valve 9 and the B port of the second differential pressure reducing valve 16 are respectively connected to the P port of the first reversing valve 10 and the P port of the second reversing valve 17; The T port of the valve 10 is connected to the T port of the second reversing valve 17; the A port and the B port of the first reversing valve 10 are respectively connected to the A1 port and the A2 port of the first hydraulic control check valve group 12, and the first The B1 port and B2 port of the hydraulic control check valve group 12 are respectively connected with the A port and the B port of the front wheel steering hydraulic cylinder 13; the A port and the B port of the first shuttle valve 11 are respectively connected with the A port of the first reversing valve 10. The port C is connected to port B, the port C of the first shuttle valve 11 is connected to the port X of the first differential pressure reducing valve 9; the port A and port B of the second reversing valve 17 are respectively connected to the second hydraulic control check valve group A1 port and A2 port of 19 are connected, B1 port and B2 port of second hydraulic control check valve group 19 are respectively connected with A port and B port of rear wheel steering hydraulic cylinder 20; A port and B port of second shuttle valve 18 The ports are respectively connected with the A port and the B port of the second reversing valve 17, and the C port of the second shuttle valve 18 is connected with the X port of the second differential pressure reducing valve 16;

The front wheel steering hydraulic cylinder 13 and the rear wheel steering hydraulic cylinder 20 are both double piston rod double acting symmetrical hydraulic cylinders.

Also includes controllers and control boxes;

The front wheel steering hydraulic cylinder 13 and the rear wheel steering hydraulic cylinder 20 are respectively connected with wire-pull displacement sensors A and B; the wire-pull displacement sensors A and B are respectively used for real-time acquisition of the travel signals A and The stroke signal B of the rear wheel steering hydraulic cylinder 20 is sent to the controller in real time;

The pressure detection device 23 is used to collect the pressure signal of the accumulator 21 in real time, and send it to the controller in real time;

The control box is provided with at least a front-wheel steering mode button, a rear-wheel steering mode button and a four-wheel steering mode button, which are respectively used to send the front-wheel steering mode signal, the rear-wheel steering mode signal and the four-wheel steering mode button to the controller according to the control of the operator. Four-wheel steering mode signal;

The controller is respectively connected with the pull-wire displacement sensor A, the pull-wire displacement sensor B, the pressure detection device 23, the first reversing valve 10, the second reversing valve 17, the third reversing valve 22, and the fourth reversing valve 24. , the fifth reversing valve 15 is connected to the control box; used to obtain the stroke information A and stroke information B according to the received stroke signals A and B; used to obtain the pressure value according to the received pressure signal, and when the pressure value is less than the set pressure When the pressure value is greater than or equal to the set pressure value, control the third reversing valve 22 to power off ; Used to control the first reversing valve 10 to work in the upper or lower position when receiving the front wheel steering mode signal, and to control the second reversing valve 17 not to energize, so as to realize the steering action only through the front wheels; for When receiving the rear wheel steering mode signal, control the second reversing valve 17 to work in the upper position or lower position, and control the first reversing valve 10 not to energize, so as to realize the steering action only through the front wheels; When the four-wheel steering mode signal is used, the first reversing valve 10 and the second reversing valve 17 are controlled to be energized at the same time to work in the upper position, or the first reversing valve 10 and the second reversing valve 17 are simultaneously controlled to be energized and work at the same time. In the lower position, and the front wheel steering mode signal is received first and then the four-wheel steering mode signal is received within the set time, the third reversing valve 22 is de-energized, the fifth reversing valve 15 is de-energized, and the fourth reversing valve is de-energized. The valve 24 is energized; when the rear wheel steering mode signal is received first and then the four-wheel steering mode signal is received within the set time, the third reversing valve 22 is de-energized, the fifth reversing valve 15 is energized, and the fourth reversing valve is energized. The valve 24 is de-energized, and according to the received travel information B and the travel information A, the front wheel steering hydraulic cylinder 13 and the rear wheel steering hydraulic cylinder 20 are kept synchronized, so as to realize the four-wheel steering action.

The first hydraulic control check valve group 12 is composed of a first hydraulic control check valve and a second hydraulic control check valve. The oil inlet and the oil outlet of the first hydraulic control check valve are respectively connected to the first hydraulic control check valve. The A1 port and B1 port of the check valve group 12, the oil inlet and the oil outlet of the second hydraulic control check valve are connected to the A2 port and the B2 port of the first hydraulic control check valve group 12, respectively. The hydraulic control port of the direction valve and the hydraulic control port of the second hydraulic control check valve are respectively connected with the oil inlet of the second hydraulic control check valve and the oil inlet of the first hydraulic control check valve;

The second hydraulic control check valve group 19 is composed of a third hydraulic control check valve and a fourth hydraulic control check valve. The oil inlet and the oil outlet of the third hydraulic control check valve are respectively connected to the second hydraulic control valve. The A1 and B1 ports of the check valve group 19, the oil inlet and the oil outlet of the fourth hydraulic control check valve are respectively connected to the A2 ports and B2 ports of the second hydraulic control check valve group 19, and the third hydraulic control single The hydraulic control port of the direction valve and the hydraulic control port of the fourth hydraulic control check valve are respectively connected with the oil inlet of the fourth hydraulic control check valve and the oil inlet of the third hydraulic control check valve.

In order to effectively filter the oil entering the system, the hydraulic pump 3 is connected to the oil tank 1 through the filter 2 .

As a preference, the controller is a PLC controller.

As a preference, the third reversing valve 22, the fourth reversing valve 24 and the fifth reversing valve 15 are all two-position two-way electromagnetic reversing valves; the third reversing valve 22 works at the left When the power is off, it works in the right position. When it works in the right position, the oil circuit between the A port and the B port is disconnected. When it works in the left position, the oil circuit between the A port and the B port is connected. ; The fourth reversing valve 24 works in the left position after being powered on, and works in the right position after power failure. When it works in the left position, the oil circuit between the A port and the B port is connected, and when it works in the right position, The oil circuit between the A port and the B port is disconnected; the fifth reversing valve 15 works in the lower position after being energized, and works in the upper position when the power is lost. When it works in the lower position, the oil between the A port and the B port The oil circuit between the A port and the B port is disconnected when it works in the upper position.

As a preference, the first reversing valve 10 is a three-position four-way electromagnetic reversing valve. When it is powered on and works in the upper position, the oil circuit between the P port and the A port is connected, and the T port and the B port are connected. The oil circuit between them is connected; when the power-off is in the neutral position, the P port and the T port are connected to each other, and the A port and the B port are mutually closed; when the power is in the lower position, the P port and the B port are connected. The oil circuit of the valve is connected, and the oil circuit between the T port and the A port is connected; the second reversing valve 17 is a three-position four-way electromagnetic reversing valve. The oil circuit is connected, and the oil circuit between the T port and the A port is connected; when the power failure is in the neutral position, the P port and the T port are connected with each other, and the A port and the B port are cut off with each other; In the upper position, the oil circuit between the P port and the A port is connected, and the oil circuit between the T port and the B port is connected.

working principle:

The engine provides power for the hydraulic system. The engine drives the hydraulic pump 3 to rotate through the coupling. The oil suction port of the hydraulic pump 3 sucks oil from the oil tank 1 through the filter 2. The filter 2 can ensure better oil cleanliness, and the hydraulic pump 3 outputs oil. The port is connected to the priority valve 6. The main oil port (CF oil port) of the priority valve 6 is connected to the P port of the hydraulic steering gear 14. The hydraulic steering gear 14 mainly includes the steering valve 7 and the metering motor 8. The LS port of the priority valve 6 (pressure-sensitive oil (port) can obtain the working pressure of the hydraulic steering gear 14 in real time, and feed the pressure back to the priority valve 6 to realize load-sensitive control, so that when the steering wheel is turned rapidly, the opening of the hydraulic steering gear 14 is large, and the steering hydraulic cylinder moves quickly, When the steering wheel rotates at a slow speed, the opening of the hydraulic steering gear 14 is small, and the steering hydraulic cylinder moves at a slow speed. The A port of the pressure valve 16, the first shuttle valve 11 and the second shuttle valve 18 can lead the pressure on the high pressure side of the actuator back to the X port (spring cavity side) of the differential pressure reducing valve, and the first differential pressure reducing The valve 9, the first shuttle valve 11, the second differential pressure reducing valve 16 and the second shuttle valve 18 constitute two groups of pressure compensators, and the pressure compensators can ensure the passage of the first reversing valve 10 and the second reversing valve 17 Flow is only related to its internal valve opening, not load pressure. For example, when the machine turns a U-turn on a slope, the load on the front and rear wheel hydraulic cylinders is not the same, and the pressure compensator can ensure that the flow through the hydraulic cylinder is precisely controlled.

The first reversing valve 10 and the second reversing valve 17 both use the M-type neutral function, that is, when the neutral is connected, the system can be unloaded. The oil outlet of the first reversing valve 10 is connected to the first hydraulically controlled one-way valve group 12, and the oil outlet of the second reversing valve 17 is connected to the second hydraulically controlled one-way valve group 19. The hydraulically controlled one-way valve group is used for Lock the corresponding steering hydraulic cylinder when it is not working Pull wire displacement sensor, the controller can determine the hydraulic cylinder position and system steering mode according to the feedback information of the pull wire displacement sensor.

The EF port (auxiliary oil port) of the priority valve 6 is connected to the A port (oil inlet) of the third reversing valve 22, and the B port (oil outlet) of the third reversing valve 22 is connected to the accumulator 21 and the pressure detection respectively. The device 23 , the B port of the fourth reversing valve 24 and the B port of the fifth reversing valve 15 are connected. The pressure detection device 23 can measure the pressure of the accumulator 21 in real time. When the pressure of the accumulator 21 is lower than the set pressure value, the controller controls the third reversing valve 22 to energize, the fourth reversing valve 24 and the fifth reversing valve The valve 15 is de-energized and the system charges the accumulator 21 . When the pressure of the accumulator 21 is higher than the set pressure value, the controller controls the third reversing valve 22 to cut off, and controls the working states of the fourth reversing valve 24 and the fifth reversing valve 15 according to actual needs.

When the system is front wheel steering, that is, the state shown in Figure 2, the controller controls the front wheel steering hydraulic cylinder 13 to work by controlling the first reversing valve 10, and the second reversing valve 17 is in the neutral position; when the system When the rear wheel is steered, that is, in the state shown in Figure 3, the controller controls the rear wheel steering hydraulic cylinder 20 to work by controlling the second reversing valve 17, and the first reversing valve 10 is in the neutral position. During wheel steering, that is, in the state shown in FIG. 4 , the first reversing valve 10 and the second reversing valve 17 connect the front wheel steering hydraulic cylinder 13 and the rear wheel steering hydraulic cylinder 20 in series (while the left Position power-on or right position power-on), at this time, the two steering hydraulic cylinders are connected in series, and the flow and displacement are exactly the same. When the system switches from two-wheel steering to four-wheel steering mode, it is assumed that the steering angle of the front wheels is not 0 and the steering angle of the rear wheels is 0, (that is, switching from the front-wheel steering mode to the four-wheel steering mode and the front wheels have been turned) At this time, the controller controls the first reversing valve 10 to be de-energized, the third reversing valve 22 to be de-energized, the fifth reversing valve 15 to be de-energized, and the fourth reversing valve 24 to be energized, and the accumulator 21 is the hydraulic pressure for the rear wheel steering. The system provides power, and the controller determines whether the upper or lower position of the second reversing valve 17 is connected to the system according to the feedback information of the pull-wire displacement sensor, and adjusts the rear wheel steering hydraulic cylinder 20 to an appropriate position based on the PID control algorithm, so that the steering system Satisfy the Ackerman steering principle (the basic requirement for a wheeled vehicle to complete the steering is that each wheel does pure rolling, that is, the axis of each wheel is required to pass through the same instantaneous center axis when the vehicle is turning, this condition is called Ackerman steering theorem. Ackerman's theorem is applicable when the vehicle speed is low and the slip angle is close to 0. In this case, there is no mutually balanced lateral force and centrifugal force.) After the adjustment is completed, the upper computer (such as a touch screen) will display the adjustment Completed information, the host computer communicates with the controller in real time. Assuming that the steering angle of the front wheels is 0, and the steering angle of the rear wheels is not 0, (that is, switching from the rear wheel steering mode to the four-wheel steering mode and the rear wheels have turned), at this time, the controller controls the second reversing valve 17 to cut off Power, the third reversing valve 22 is de-energized, the fourth reversing valve 24 is de-energized, the fifth reversing valve 15 is energized, the accumulator 21 provides power for the front wheel steering hydraulic system. information, control the left or right position of the first reversing valve 10 to connect to the system, and adjust the front wheel steering hydraulic cylinder 13 to an appropriate position based on the PID control algorithm, so that the steering system satisfies the Ackerman steering principle, after the adjustment is completed , the host computer (such as touch screen) will display the information of the adjustment completed, and the host computer communicates with the controller in real time.

Claims (7)

1. A multi-mode steering system, comprising a hydraulic pump (3) and a fuel tank (1), characterized in that it also comprises a priority valve (6), a hydraulic steering gear (14), a relief valve (5), a third shifter Directional valve (22), first differential pressure reducing valve (9), fifth reversing valve (15), second differential pressure reducing valve (16), fourth reversing valve (24), pressure detection device ( 23), front wheel steering hydraulic cylinder (13), first reversing valve (10), second reversing valve (17), first hydraulic control check valve group (12), first shuttle valve (11), A second hydraulic control check valve group (19), a rear wheel steering hydraulic cylinder (20) and a second shuttle valve (18); The oil inlet and oil outlet of the hydraulic pump (3) are respectively connected with the oil tank (1) and the P port of the priority valve (6), and the oil outlet of the hydraulic pump (3) is also connected to the oil tank through the safety valve (4). (1) Connection; the CF port and the LS port of the priority valve (6) are respectively connected with the P port and the LS port of the hydraulic steering gear (14), and the P port of the priority valve (6) is connected to the hydraulic steering gear (14) through the relief valve (5). The CF port of the priority valve (6) is connected; the EF port of the priority valve (6) is connected to the A port of the third reversing valve (22); the A port of the steering gear (14) is respectively connected with the first differential pressure reducing valve ( 9) port A is connected with port A of the fifth reversing valve (15); port B of the steering gear (14) is respectively connected with port A of the second differential pressure reducing valve (16) and the fourth reversing valve (24). ) is connected to port A of ); the port B of the third reversing valve (22), the port B of the fourth reversing valve (24), the port B of the fifth reversing valve (15) and the pressure detection device (23) are all connected to The accumulator (21) is connected; Port B of the first differential pressure reducing valve (9) and port B of the second differential pressure reducing valve (16) are respectively connected with the port P of the first reversing valve (10) and the port of the second reversing valve (17). The P port is connected; the T port of the first reversing valve (10) is connected to the T port of the second reversing valve (17); the A port and the B port of the first reversing valve (10) are respectively connected with the first hydraulic control unit Connect to the A1 port and A2 port of the valve group (12), and connect the B1 port and B2 port of the first hydraulic control check valve group (12) to the A port and B port of the front wheel steering hydraulic cylinder (13) respectively; Port A and port B of a shuttle valve (11) are respectively connected to ports A and B of the first reversing valve (10), and port C of the first shuttle valve (11) is connected to the first differential pressure reducing valve (9). ) is connected to port X of ); ports A and B of the second reversing valve (17) are respectively connected to ports A1 and A2 of the second hydraulic control check valve group (19), and the second hydraulic control check valve group ( 19) ports B1 and B2 are respectively connected with ports A and B of the rear wheel steering hydraulic cylinder (20); ports A and B of the second shuttle valve (18) are respectively connected with ports A and B of the second reversing valve (17). Port A and port B are connected, and port C of the second shuttle valve (18) is connected to port X of the second differential pressure reducing valve (16); The front wheel steering hydraulic cylinder (13) and the rear wheel steering hydraulic cylinder (20) are both double piston rod double acting symmetrical hydraulic cylinders. 2. A kind of multi-mode steering system according to claim 1, is characterized in that, also comprises controller and control box; The front wheel steering hydraulic cylinder (13) and the rear wheel steering hydraulic cylinder (20) are respectively connected with pull-wire type displacement sensors A and B; the pull-wire type displacement sensors A and B are respectively used for real-time acquisition of the front wheel steering hydraulic cylinder (13) ) of the stroke signal A and the stroke signal B of the rear wheel steering hydraulic cylinder (20), and send them to the controller in real time; The pressure detection device (23) is used to collect the pressure signal of the accumulator (21) in real time, and send it to the controller in real time; The control box is provided with at least a front-wheel steering mode button, a rear-wheel steering mode button and a four-wheel steering mode button, which are respectively used to send the front-wheel steering mode signal, the rear-wheel steering mode signal and the four-wheel steering mode button to the controller according to the control of the operator. Four-wheel steering mode signal; The controller is respectively connected with the pull-wire displacement sensor A, the pull-wire displacement sensor B, the pressure detection device (23), the first reversing valve (10), the second reversing valve (17), and the third reversing valve (22). ), the fourth reversing valve (24), the fifth reversing valve (15) and the control box are connected; used to obtain stroke information A and stroke information B according to the received stroke signals A and B; used to obtain stroke information A and B according to the received pressure signal The pressure value is obtained, and when the pressure value is less than the set pressure value, the third reversing valve (22) is controlled to be energized, the fourth reversing valve (24) is de-energized, and the fifth reversing valve (15) is de-energized. When the value is greater than or equal to the set pressure value, the third reversing valve (22) is controlled to be de-energized; it is used to control the first reversing valve (10) to work in the upper or lower position when receiving the front wheel steering mode signal. And control the second reversing valve (17) not to be electrified, so as to realize the steering action only through the front wheel; it is used to control the second reversing valve (17) to work in the upper or lower position when it receives the rear wheel steering mode signal. , and control the first reversing valve (10) without electricity, so as to realize the steering action only through the front wheels; it is used to control the first reversing valve (10) and the second reversing valve at the same time when receiving the four-wheel steering mode signal The valve (17) is energized at the same time to work in the upper position, or the first reversing valve (10) and the second reversing valve (17) are simultaneously controlled to be energized and work in the lower position at the same time, and the front wheel steering is first received within the set time. When the four-wheel steering mode signal is received after the mode signal, the first reversing valve (10) is de-energized, the third reversing valve (22) is de-energized, the fifth reversing valve (15) is de-energized, and the fourth reversing valve (15) is de-energized. The valve (24) is energized and the second reversing valve (17) is energized; when the rear wheel steering mode signal is received first and then the four-wheel steering mode signal is received within the set time, the second reversing valve (17) is controlled ), the third reversing valve (22) is de-energized, the fifth reversing valve (15) is energized, the fourth reversing valve (24) is de-energized, the first reversing valve (10) is energized, and according to the reception The stroke information B matches the stroke information A, so that the front wheel steering hydraulic cylinder (13) and the rear wheel steering hydraulic cylinder (20) keep synchronous action, so as to realize the four-wheel steering action. 3. A multi-mode steering system according to claim 1 or 2, wherein the first hydraulic control check valve group (12) consists of a first hydraulic control check valve and a second hydraulic control check valve Valve composition, the oil inlet and oil outlet of the first hydraulic control check valve are respectively connected to the A1 port and B1 port of the first hydraulic control check valve group (12), and the oil inlet and B1 port of the second hydraulic control check valve are respectively connected. The oil outlet is respectively connected to the A2 port and the B2 port of the first hydraulic control check valve group (12). The hydraulic control port of the first hydraulic control check valve and the hydraulic control port of the second hydraulic control check valve are respectively connected with the second hydraulic control check valve The oil inlet of the hydraulic control check valve is connected with the oil inlet of the first hydraulic control check valve; The second hydraulic control check valve group (19) is composed of a third hydraulic control check valve and a fourth hydraulic control check valve, and the oil inlet and the oil outlet of the third hydraulic control check valve are respectively connected to the second hydraulic control check valve. Ports A1 and B1 of the hydraulic control check valve group (19), and the oil inlet and oil outlet of the fourth hydraulic control check valve are respectively connected to the A2 ports and B2 ports of the second hydraulic control check valve group (19). , the hydraulic control port of the third hydraulic control check valve and the hydraulic control port of the fourth hydraulic control check valve are respectively connected with the oil inlet of the fourth hydraulic control check valve and the oil inlet of the third hydraulic control check valve . 4. A multi-mode steering system according to claim 3, wherein the hydraulic pump (3) is connected to the oil tank (1) through a filter (2). 5 . The multi-mode steering system according to claim 4 , wherein the controller is a PLC controller. 6 . 6. A multi-mode steering system according to claim 5, wherein the third reversing valve (22), the fourth reversing valve (24) and the fifth reversing valve (15) are all Two-position, two-way electromagnetic reversing valve; the third reversing valve (22) works in the left position after being powered on, and works in the right position after power failure. When it works in the right position, the oil between the A port and the B port When the circuit is disconnected, when it works in the left position, the oil circuit between the A port and the B port is connected; the fourth reversing valve (24) works in the left position after being energized, and works in the right position after power failure, and its working In the left position, the oil circuit between the A port and the B port is connected, and when it works in the right position, the oil circuit between the A port and the B port is disconnected; after the fifth reversing valve (15) is energized When it works in the lower position, it works in the upper position when the power is lost. When it works in the lower position, the oil circuit between the A port and the B port is connected. When it works in the upper position, the oil circuit between the A port and the B port is disconnected. 7. A multi-mode steering system according to claim 6, characterized in that the first reversing valve (10) is a three-position four-way electromagnetic reversing valve, and when it is powered on and works in the upper position, its P The oil circuit between the port and the A port is connected, and the oil circuit between the T port and the B port is connected; when the power failure is in the neutral position, the P port and the T port are connected with each other, and the A port and the B port are mutually blocked. ; When it is powered on and works in the lower position, the oil circuit between its P port and B port is connected, and the oil circuit between its T port and A port is connected; the second reversing valve (17) is a three-position four-way electromagnetic switch. To the valve, when it is powered on and works in the lower position, the oil circuit between the P port and the B port is connected, and the oil circuit between the T port and the A port is connected; when the power is lost, the P port and the A port are connected. The T port is connected to each other, and its A port and B port are mutually closed; when it is powered on and works in the upper position, the oil circuit between the P port and the A port is connected, and the oil circuit between the T port and the B port is connected.

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