Unmanned full-hydraulic steering system for mining dump trucks and its usage method

Abstract

Unmanned full-hydraulic steering system and usage method for mining dump trucks. The oil outlet end of a hydraulic pump is connected to a steering cylinder through a flow amplifier. The flow amplifier is connected to a steering gear and an electro-hydraulic steering valve through a reversing valve. Both ends of the reversing valve are respectively connected to a mode switching valve and a displacement sensor I. The mode switching valve is arranged at the oil outlet of the hydraulic pump, and the displacement sensor I is connected to a controller. The present invention enables the mining dump truck to have both manual steering and unmanned steering functions. The unmanned steering system can reduce the labor intensity of the driver and improve production efficiency. Moreover, the priority of manual steering operation is higher than that of unmanned steering operation, ensuring that the steering wheel is always in a normal operation state, the vehicle safety, and the driver's full control over the steering action. At the same time, when the electro-hydraulic proportional steering system is working, it will monitor the running state of the vehicle in real time, such as speed, steering wheel angle, etc., and automatically perform steering actions and action adjustments according to the real-time state of the vehicle, improving the intelligent level of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of mining machinery, and particularly to an unmanned full-hydraulic steering system for mining dump trucks and a using method thereof. Background Art

[0002] A mining dump truck refers to a special load-carrying vehicle used for short-distance transportation to complete the tasks of rock and soil stripping and ore transportation on special roads such as open-pit mines or large-scale civil engineering sites. It is widely used in various open-pit mines, hydropower projects, railway and highway construction projects, and large-scale construction projects. Due to the large load capacity of mining dump trucks, all mining dump trucks adopt a full-hydraulic steering system - there is no mechanical connection between the steering wheel and the steering tires, and the steering tires are completely driven by hydraulic cylinders. With the improvement of automation technology and communication technology, unmanned driving technology has emerged, and there is a need for an unmanned full-hydraulic steering system that can match the manual full-hydraulic steering system. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the above-mentioned prior art, and provide an unmanned full-hydraulic steering system for mining dump trucks and a using method thereof with simple structure and good effect, so as to realize the unmanned operation of the full-hydraulic steering system of mining dump trucks.

[0004] The present invention is realized as follows: An unmanned full-hydraulic steering system for mining dump trucks includes a hydraulic pump. The oil outlet end of the hydraulic pump is connected to a steering cylinder through a flow amplifier. The steering cylinder includes a left steering cylinder and a right steering cylinder. The flow amplifier is connected to a steering gear and an electronic control steering valve through a reversing valve. Both ends of the reversing valve are respectively connected to a mode switching valve and a displacement sensor I. The mode switching valve is arranged at the oil outlet of the hydraulic pump, and the displacement sensor I is connected to a controller;

[0005] The flow amplifier includes a priority valve and a confluence valve. The P, L, R, and LS oil ports of the flow amplifier are connected to the P, L, R, and LS oil ports of the steering gear and the electronic control steering valve through a reversing valve;

[0006] The steering gear is rigidly connected to a corner sensor and a steering wheel;

[0007] The electronic control steering valve includes a control valve group, a proportional reversing valve, and a shuttle valve. The control valve group is connected to both ends of the electronic control steering valve. The shuttle valve is arranged at the oil outlet end of the proportional reversing valve and is connected to the L, R, and LS oil ports of the electronic control steering valve;

[0008] The controller is further connected to a corner sensor, a stroke sensor, a vehicle speed sensor, a GPS signal, and a displacement sensor II. The stroke sensor is arranged on the left steering cylinder and the right steering cylinder. The displacement sensor II is arranged at the control end of the electronic control steering valve.

[0009] Furthermore, the priority valve is a two-position three-way hydraulic control valve. The two hydraulic control ends of the priority valve are respectively connected to the P and LS ports of the flow amplifier, and a spring is provided at the control end connected to the LS port.

[0010] The confluence valve is provided with P, L, R, T, CL, and CR ports. The P, L, R, and T ports of the confluence valve are connected to the P, L, R, and T ports of the flow amplifier, and the CL and CR ports are connected to the left steering cylinder and the right steering cylinder together.

[0011] The reversing valve is a two-position twelve-way hydraulic control reversing valve.

[0012] The mode switching valve is a two-position three-way electromagnetic reversing valve. The mode switching valve is connected to the oil outlet end of the hydraulic pump through an overflow valve and a pressure reducing valve.

[0013] The control valve group includes a normally open switch valve I, a normally closed switch valve I, a normally open switch valve II, and a normally closed switch valve II. The normally open switch valve I and the normally closed switch valve I are arranged in parallel at one end of the electro-hydraulic steering valve, and the normally open switch valve II and the normally closed switch valve II are arranged in parallel at the other end of the electro-hydraulic steering valve.

[0014] The normally open switch valve I, the normally closed switch valve I, the normally open switch valve II, and the normally closed switch valve II are all two-position two-way high-frequency switch valves.

[0015] The proportional reversing valve is a three-position five-way hydraulic control reversing valve. The oil inlet end of the proportional reversing valve is connected to the P port of the electro-hydraulic steering valve, and the oil outlet end of the proportional reversing valve is connected to the L and R ports of the electro-hydraulic steering valve through a shuttle valve.

[0016] The usage method of the fully hydraulic steering system for unmanned mining dump trucks includes a manual steering mode, an unmanned steering mode, and an emergency steering mode.

[0017] The steering operation method in the manual steering mode is as follows:

[0018] S1. The mode switching valve is not electrified, and the controller does not participate in the steering action.

[0019] S2. The reversing valve is in the initial working position, and the flow amplifier is connected to the steering gear.

[0020] S3. The driver turns the steering wheel, and the steering wheel drives the angle sensor and the steering gear to rotate synchronously.

[0021] S4. Under the action of the steering gear, the P port of the flow amplifier is connected to the L and LS ports or the P port is communicated with the LS and R ports.

[0022] S5. The large flow hydraulic oil output by the hydraulic pump is supplied to the steering cylinder through the flow amplifier and the steering gear;

[0023] S6. The steering cylinder drives the tires of the dump truck to rotate, and the piston rods of the left steering cylinder and the right steering cylinder retract or extend to achieve the steering action;

[0024] The steering operation method of the unmanned steering mode is as follows:

[0025] T1, the mode switching valve is energized, the hydraulic oil is supplied to the control end of the reversing valve through the mode switching valve, the reversing valve changes its working position, and the flow amplifier is connected to the proportional reversing valve;

[0026] T2, displacement sensor I transmits the displacement signal of the reversing valve to the controller, and the dump truck officially enters the unmanned steering mode;

[0027] T3, the controller monitors the working status of the angle sensor, travel sensor, speed sensor, GPS signal and displacement sensor II in real time;

[0028] T4. When the dump truck needs to turn, the controller gives a turning command, controls the proportional reversing valve to switch different working positions through the control valve group, and connects the P port of the flow amplifier with the L and LS ports or connects the P port with the LS and R ports;

[0029] T5. The large flow hydraulic oil output by the hydraulic pump is supplied to the steering cylinder through the flow amplifier and the proportional reversing valve;

[0030] T6. The controller monitors the signal of displacement sensor II in real time to judge the displacement of the proportional reversing valve;

[0031] T7. When the displacement of the proportional reversing valve reaches the predetermined position, the controller controls the control valve group to cut off all the control oil circuits on the left and right sides of the proportional reversing valve, and the proportional reversing valve remains at the predetermined displacement position to continue the steering action;

[0032] T8. When the dump truck is released from the steering condition, the control valve group shall not be energized. When the pressure at both ends of the proportional reversing valve is relieved and the valve returns to the middle position, the dump truck returns to the non-steering condition.

[0033] The operation method of emergency steering mode is as follows:

[0034] E1. When the driver operates the steering wheel in the unmanned steering mode, the steering wheel drives the angle sensor and the steering gear to move synchronously;

[0035] E2, the angle sensor sends a signal to the controller;

[0036] E3, the controller control mode switching valve and control valve group are powered off;

[0037] E4. The reversing valve resets, the flow amplifier is connected to the steering gear, and the vehicle enters the manned steering mode.

[0038] When the P port of the flow amplifier is connected to the L and LS ports, the P ports of the confluence valves are both connected to the CL port of the confluence valve. At the same time, the hydraulic oil at the LS port of the flow amplifier reaches one side control oil port of the priority valve, and the other side control oil port of the priority valve is connected to the P port of the flow amplifier. The control hydraulic oil pressures on both sides of the priority valve are the same. Under the thrust of the spring on one side, the priority valve displaces to the working position.

[0039] The present invention has the following advantages: The unmanned full-hydraulic steering system and its usage method for mining dump trucks of the present invention enable mining dump trucks to have both manual steering and unmanned steering functions. The unmanned steering system can reduce the labor intensity of drivers and improve production efficiency; and the manual steering operation has a higher priority than the unmanned steering operation, ensuring that the steering wheel is always in a normal operation state, the vehicle safety, and the driver's full control over the steering action; at the same time, when the electro-hydraulic proportional steering system works, it will monitor the running state of the vehicle in real time, such as speed, steering wheel angle, etc., and automatically perform steering actions and action adjustments according to the real-time state of the vehicle, improving the intelligent level of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the hydraulic principle of the invention.

[0041] In the figure: 1, hydraulic pump; 2, pressure reducing valve; 3, overflow valve; 4, mode switching valve; 5, steering gear; 6, corner sensor; 7, reversing valve; 8, displacement sensor I; 9, steering cylinder; 9.1, left steering cylinder; 9.2, right steering cylinder; 10, stroke sensor; 11, flow amplifier; 12, priority valve; 13, vehicle speed sensor; 14, GPS signal; 15, controller; 16, shuttle valve; 17, II; 18, proportional reversing valve; 19, normally open switch valve I; 20, normally closed switch valve I; 21, normally open switch valve II; 22, normally closed switch valve II; 23, electro-hydraulic steering valve; 24, steering wheel; 25, hydraulic oil tank; 26, confluence valve. DETAILED DESCRIPTION OF THE INVENTION

[0042] The following is a description of the preferred embodiments of the present invention for the invention patent with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention patent and are not used to limit the present invention patent.

[0043] As Figure 1The shown unmanned full-hydraulic steering system for mining dump trucks includes a hydraulic pump 1. The oil outlet end of the hydraulic pump 1 is connected to a steering cylinder 9 through a flow amplifier 11. The steering cylinder 9 includes a left steering cylinder 9.1 and a right steering cylinder 9.2. The hydraulic pump of the present invention is a constant-pressure variable hydraulic pump. When the dump truck does not require a steering action, the flow rate required by the steering hydraulic system is very small at this time, so the hydraulic pump is in a high-pressure and small-displacement standby state. When the vehicle requires a steering action, the hydraulic pump will be in a high-pressure and large-displacement state to ensure the flow rate of hydraulic oil required for the steering action. The hydraulic pump is connected to the steering cylinder through a flow amplifier. The piston rod of the steering cylinder is rigidly connected to the steering tire of the dump truck. By the extension and retraction of the steering cylinder, the tire is driven to swing, thereby realizing the steering of the dump truck. Among them, the oil ports of the steering cylinder are cross-connected, that is, the rodless cavity of the left steering cylinder is connected to the rod cavity of the right steering cylinder, and the rod cavity of the left steering cylinder is connected to the rodless cavity of the right steering cylinder. When turning left, hydraulic oil flows into the rodless cavity of the left steering cylinder and the rod cavity of the right steering cylinder at the same time. The piston rod of the left steering cylinder retracts, and the piston rod of the right steering cylinder extends, thereby realizing the left-turning action. The right-turning is the same principle.

[0044] As Figure 1 shown in the unmanned full-hydraulic steering system for mining dump trucks, the flow amplifier 11 includes a priority valve 12 and a confluence valve 26. The priority valve 12 is a two-position three-way hydraulic control valve. The two hydraulic control ends of the priority valve 12 are respectively connected to the P and LS oil ports of the flow amplifier 11. A spring is provided at the control end connected to the LS oil port. The priority valve of the present invention is a hydraulic control valve. The two control ends are respectively connected to the P and LS oil ports of the flow amplifier. The P port is a high-pressure hydraulic oil port, and the LS port is a feedback port. From Figure 1It can be known that there is always hydraulic oil at port P of the flow amplifier. Therefore, there is always a control pressure at the left end of the priority valve connected to port P. Since there is also a spring at the right end of the priority valve connected to port LS, when there is no pressure oil at port LS, the pressure of the spring is less than the oil pressure at port P. Therefore, the priority valve is in the left working position. When ports P and LS of the flow amplifier are connected, the control hydraulic oil pressures at both ends of the priority valve are the same. Under the action of the spring, the overall control pressure at the right end of the priority valve is greater than that at the left end. Therefore, at this time, the priority valve is in the right working position. The confluence valve 26 is used to confluence the control oil from the reversing valve 7 and the hydraulic oil output by the hydraulic pump 1 and supply it to the steering cylinder. Ports P, L, R, T, CL, and CR are provided on the confluence valve 26. Ports P, L, R, and T of the confluence valve 26 are connected to ports P, L, R, and T of the flow amplifier 11, and ports CL and CR are connected to the left steering cylinder 9.1 and the right steering cylinder 9.2. The confluence valve is controlled by the hydraulic oil at ports L and R. When ports P and L of the flow amplifier are connected, ports P and L of the confluence valve are both connected to port CL of the confluence valve, and then connected to port CL of the flow amplifier. The hydraulic oil output by the hydraulic pump can be supplied to the steering cylinder through port CL of the flow amplifier, specifically to the rodless cavity of the left steering cylinder and the rod chamber of the right steering cylinder, realizing the left turn action. The right turn is the same principle.

[0045] As Figure 1 shown in the unmanned full-hydraulic steering system of a mining dump truck, the flow amplifier 11 is connected to a steering gear 5 and an electro-hydraulic control valve 23 through a reversing valve 7. Ports P, L, R, and LS of the flow amplifier 11 are connected to ports P, L, R, and LS of the steering gear 5 and the electro-hydraulic control valve 23 through the reversing valve 7. The flow amplifier of the present invention is provided with ports P, L, R, and LS. The connection between port P and ports L, R, and LS is realized through the steering gear and the electro-hydraulic control valve. When connected to the steering gear, it is in the manual steering mode. When connected to the electro-hydraulic control valve, it is in the unmanned steering mode. The switching between the steering gear and the electro-hydraulic control valve is realized through the reversing valve. After receiving the small-flow control oil from the steering gear or the proportional reversing valve, the flow amplifier opens the priority valve, allowing a large flow to pass through the flow amplifier and be supplied to the steering cylinder. Port EF of the flow amplifier 11 is in a closed state in the hydraulic principle of the present invention.

[0046] As Figure 1The unmanned fully hydraulic steering system of the mining dump truck shown, both ends of the reversing valve 7 are respectively connected with a mode switching valve 4 and a displacement sensor I 8, and the reversing valve 7 is a two-position twelve-way hydraulically controlled reversing valve. The displacement sensor I 8 is connected with a controller 15. The reversing valve of the present invention has two working modes, namely the left position and the right position, which respectively correspond to the oil port connection modes under unmanned steering and manual steering. The mode switching valve is used to control the on-off of the hydraulic oil leading to the reversing valve and the electro-hydraulic steering valve. In the manual steering mode, the mode switching valve is not powered, and the hydraulic oil will not be supplied to the reversing valve and the electro-hydraulic steering valve; in the unmanned steering mode, the mode switching valve is powered, and the hydraulic oil is supplied to the reversing valve and the electro-hydraulic steering valve. At the same time, the displacement sensor I can detect the displacement of the reversing valve and transmit the displacement signal of the reversing valve to the controller. When the controller determines that the reversing valve is in the left position working mode according to the signal of the displacement sensor I, the dump truck officially enters the unmanned steering mode.

[0047] As Figure 1 The unmanned fully hydraulic steering system of the mining dump truck shown, the mode switching valve 4 is arranged at the oil outlet of the hydraulic pump 1; the mode switching valve 4 is a two-position three-way electromagnetic reversing valve, and the mode switching valve 4 is connected with the oil outlet end of the hydraulic pump 1 through an overflow valve 3 and a pressure reducing valve 2. The pressure reducing valve reduces the pressure of the hydraulic oil provided by the hydraulic pump and then supplies it to the left control oil chamber of the reversing valve and the electro-hydraulic steering valve; the overflow valve is used to protect the hydraulic components in the hydraulic system. When the system fails and the pressure rises abnormally, the overflow valve will open to control the pressure of the hydraulic system at the set pressure of the overflow valve.

[0048] As Figure 1 The unmanned fully hydraulic steering system of the mining dump truck shown, the steering gear 5 is rigidly connected with a corner sensor 6 and a steering wheel 24. The steering gear is a control component in the manual steering mode, used to control the movement direction of the steering cylinder, so as to control the mining dump truck to turn left or right. The corner sensor is used to monitor the rotation of the steering wheel, and the corner sensor transmits the signal to the controller.

[0049] As Figure 1The shown fully hydraulic steering system for driverless mining dump trucks. The electro-hydraulic steering valve 23 includes a control valve group, a proportional directional valve 18, and a shuttle valve 16. The control valve group is connected to both ends of the electro-hydraulic steering valve 23. The shuttle valve 16 is arranged at the oil outlet end of the proportional directional valve 18 and is connected to the L, R, and LS ports of the electro-hydraulic steering valve 23. The control valve group includes a normally open switch valve I 19, a normally closed switch valve I 20, a normally open switch valve II 21, and a normally closed switch valve II 22. The normally open switch valve I 19 and the normally closed switch valve I 20 are arranged in parallel at one end of the electro-hydraulic steering valve 23. The normally open switch valve II 21 and the normally closed switch valve II 22 are arranged in parallel at the other end of the electro-hydraulic steering valve 23. The normally open switch valve I 19, the normally closed switch valve I 20, the normally open switch valve II 21, and the normally closed switch valve II 22 are all two-position two-way high-frequency switch valves. The proportional directional valve 18 is a three-position five-way hydraulically controlled directional valve. The oil inlet end of the proportional directional valve 18 is connected to the P port of the electro-hydraulic steering valve 23. The oil outlet end of the proportional directional valve 18 is connected to the L and R ports of the electro-hydraulic steering valve 23 through the shuttle valve 16.

[0050] As Figure 1 The shown fully hydraulic steering system for driverless mining dump trucks. The controller 15 is also connected to a steering angle sensor 6, a stroke sensor 10, a vehicle speed sensor 13, a GPS signal 14, and a displacement sensor II 17. The stroke sensor 10 is arranged on the left steering cylinder 9.1 and the right steering cylinder 9.2. The displacement sensor II 17 is arranged at the control end of the electro-hydraulic steering valve 23. The stroke sensor of the present invention is used to detect the piston rod stroke of the steering cylinder and is connected to the controller. The piston rod of the steering cylinder is rigidly connected to the steering tire of the dump truck. By the extension and retraction of the steering cylinder, the tire is driven to swing, thereby realizing the steering of the dump truck. The controller can judge the swing angle of the steering tire according to the stroke signal of the stroke sensor, and thus obtain the motion state of the steering tire. The vehicle speed sensor and the GPS signal are used to help judge the real-time position of the vehicle, which is convenient for the controller to issue control instructions according to the actual situation in the driverless steering mode. The displacement sensor II is used to transmit the displacement signal of the electro-hydraulic steering valve to the controller, which is convenient for the controller to control the action of the electro-hydraulic steering valve.

[0051] The method of the fully hydraulic steering system for driverless mining dump trucks of the present invention includes an artificial steering mode, a driverless steering mode, and an emergency steering mode. The specific operation methods and principles are as follows.

[0052] Artificial steering mode:

[0053] In the manual steering mode, the controller 15 does not participate in the steering action, and the mode switching valve 4, the normally open switch valve I19, the normally closed switch valve I20, the normally open switch valve II21, and the normally closed switch valve II22 are all powered off. Since the mode switching valve 4 is powered off, the mode switching valve 4 is in the right position. The pressure oil output by the hydraulic pump 1 is cut off at the P port of the mode switching valve 4 after passing through the pressure reducing valve 2, and the other way reaches the HP port of the flow amplifier. The mode switching valve 4 is in the right position, so the left control oil chamber of the reversing valve 7 is directly connected to the hydraulic oil tank 25. The reversing valve 7 moves to the left under the thrust of the spring on the right side of the valve core and is in the right position. The steering wheel 24 is rigidly connected with the steering gear 5 and the angle sensor 6 to maintain synchronous movement.

[0054] When the dump truck is in a non-steering condition, the steering wheel 24 remains stationary, and the hydraulic oil output by the hydraulic pump 1 reaches the priority valve 12 through the HP port of the flow amplifier 11. No matter whether the priority valve 12 is in the left or right position, the hydraulic oil from the HP port of the flow amplifier can be connected to the P port of the flow amplifier through the priority valve 12, and the hydraulic oil passing through the P port and LS port of the flow amplifier flows to the P port and LS port of the steering gear 5 through the right position of the reversing valve 7. Since it is in a non-rotating condition at this time, the P port of the steering gear is not connected to the L, R, T, and LS ports of the steering gear and is in a cut-off state. The L, R, and LS oil ports of the steering gear are connected to the T port of the flow amplifier through the T port of the steering gear, and the T port of the flow amplifier is connected to the hydraulic oil tank 25 through the HT port of the flow amplifier. Since the P port of the steering gear is in a cut-off state, the L port and the R port of the converging valve 26 do not have the control oil from the steering gear 5. All oil ports on the converging valve 26 are in the cut-off state at this time; the pressure of the control oil chamber on the left side of the priority valve 12 is the same as the pressure output by the hydraulic pump 1, and the control oil chamber on the right side of the priority valve 12 is connected to the hydraulic oil tank 25 through the LS port, and the thrust of the control spring on the right side of the priority valve 12 is much smaller than the thrust generated by the control oil chamber on the left side of the priority valve 12, so the priority valve 12 moves right under the action of the hydraulic oil in the left control oil chamber and works in the left position. When the priority valve 12 is in the left position, the hydraulic oil output by the priority valve 12 is cut off at the P port of the steering gear and at the EF port of the flow amplifier 11. At this point, the hydraulic oil output by the hydraulic pump 1 is in the cut-off state at the P port of the mode switching valve 4, the P port of the steering gear 5, the EF port of the flow amplifier 11, and the P port of the converging valve 26. The hydraulic pump 1 is in a high-pressure and small-displacement state, and the hydraulic steering system is in a high-pressure and small-displacement standby state.

[0055] When the driver turns the steering wheel 24 to the left, the steering wheel 24 drives the steering angle sensor 6 and the steering gear 5 to rotate synchronously. At this time, the P port of the steering gear 5 is connected with the L port and the LS port, the R port of the steering gear 5 is connected with the T port, and the L port and the LS port of the steering gear are connected with the L port and the LS port of the flow amplifier 11 respectively. Under the action of the hydraulic oil of the L port of the flow amplifier 11, the P port and the L port of the converging valve 26 are both connected with the CL port of the converging valve 26, and then connected with the CL port of the flow amplifier. At the same time, the hydraulic oil of the LS port of the flow amplifier 11 reaches the right control oil port of the priority valve 12, and the left control oil port of the priority valve 12 is connected with the P port of the flow amplifier. Since the control oil thrust of the right side of the priority valve plus the spring thrust of the right side is greater than the control oil thrust of the left side of the priority valve 12, the priority valve 12 moves to the left, and the priority valve 12 is in the right position. Since the priority valve 12 is in the right position, the pressure from the flow amplifier 11 The hydraulic oil at the HP port can only be supplied to the steering gear 5 and the flow amplifier 11 through the priority valve 12, and cannot be supplied to the EF port of the flow amplifier 11. At this time, the priority valve 12 allows a large flow of hydraulic oil from the hydraulic pump 1 to pass through. In summary, when the driver turns the steering wheel left, the hydraulic oil output by the hydraulic pump 1 is all supplied to the CL port of the flow amplifier 11. Since the CL port is connected to the steering cylinder 9, the hydraulic pump 1 switches from a high-pressure, small-displacement state with no steering action to a high-pressure, large-displacement state to meet the oil supply demand of the steering cylinder 9. At this point, the large-flow hydraulic oil output by the hydraulic pump 1 is all supplied to the steering cylinder 9 through the flow amplifier 11 and the steering gear 5. The steering cylinder 9 is mechanically connected to the dump truck tire, so the action of the steering cylinder 9 drives the dump truck tire to rotate. At this time, the piston rod of the left steering cylinder 9.1 retracts, and the piston rod of the right steering cylinder 9.2 extends, thereby realizing the left steering action.

[0056] When the driver turns the steering wheel 24 to the right, the steering wheel 24 drives the steering angle sensor 6 and the steering gear 5 to rotate synchronously. At this time, the P port of the steering gear 5 is connected with the R port and the LS port, the L port of the steering gear 5 is connected with the T port, and the R port and the LS port of the steering gear are connected with the R port and the LS port of the flow amplifier 11 respectively. Under the action of the hydraulic oil of the R port of the flow amplifier 11, the P port and the R port of the combining valve 26 are connected with the CR port of the combining valve 26, and then connected with the CR port of the flow amplifier. At the same time, the hydraulic oil of the LS port of the flow amplifier 11 reaches the right control oil port of the priority valve 12, and the left control oil port of the priority valve 12 is connected with the P port of the flow amplifier. Since the control oil thrust of the right side of the priority valve plus the spring thrust of the right side is greater than the control oil thrust of the left side of the priority valve 12, the priority valve 12 moves to the left, and the priority valve 12 is in the right position. The hydraulic oil at the HP port can only be supplied to the steering gear 5 and the flow amplifier 11 through the priority valve 12, and cannot be supplied to the EF port of the flow amplifier 11. At this time, the priority valve 12 allows a large flow of hydraulic oil from the hydraulic pump 1 to pass through. In summary, when the driver turns the steering wheel right, the hydraulic oil output by the hydraulic pump 1 is all supplied to the CR port of the flow amplifier 11. Since the CR port is connected to the steering cylinder 9, the hydraulic pump 1 switches from a high-pressure, small-displacement state with no steering action to a high-pressure, large-displacement state to meet the oil supply demand of the steering cylinder 9. At this point, the large-flow hydraulic oil output by the hydraulic pump 1 is all supplied to the steering cylinder 9 through the flow amplifier 11 and the steering gear 5. The steering cylinder 9 is mechanically connected to the dump truck tire, so the action of the steering cylinder 9 drives the dump truck tire to rotate. At this time, the piston rod of the left steering cylinder 9.1 extends, and the piston rod of the right steering cylinder 9.2 retracts, thereby realizing the right steering action.

[0057] Unmanned steering mode:

[0058] To enter the unmanned steering mode, firstly, the mode switching valve 4 is energized and works in the left position. The hydraulic oil output by the hydraulic pump 1 is supplied to the left control oil chamber of the reversing valve 7 and the electronically controlled steering valve 23 after passing through the pressure reducing valve 2 and the left position of the mode switching valve 4. The thrust generated by the left control oil chamber of the reversing valve 7 is greater than the thrust of the right spring of the reversing valve 7. Therefore, under the action of the thrust of the left control oil chamber, the reversing valve 7 moves right, and the hydraulic oil in the right control chamber of the reversing valve 7 returns to the hydraulic oil tank 25. The reversing valve 7 works in the left position. The displacement sensor Ⅰ8 can detect the displacement of the reversing valve 7 and transmit the displacement signal of the reversing valve 7 to the controller 15. When the controller 15 determines that the reversing valve 7 is working in the left position according to the signal of the displacement sensor Ⅰ8, the dump truck officially enters the unmanned steering mode.

[0059] In the unmanned steering mode, the controller 15 monitors the working states of the steering angle sensor 6, the stroke sensor 10, the speed sensor 13, the GPS signal 14, and the displacement sensor II 17 in real time. The stroke sensor 10 is used to monitor the extension stroke of the oil cylinder 9. The controller 15 judges the real-time position of the vehicle according to the GPS signal 15 and the speed sensor 13. The controller 15 judges the steering angle of the vehicle tires according to the stroke sensor 10, and adjusts the steering action of the vehicle in real time according to the relative position relationship between the steering angle of the tires, the real-time position of the vehicle, and the planned route. That is, the proportional directional valve 18 will continuously switch between the left position, the middle position, and the right position. In order to improve the response speed and accuracy of the proportional directional valve 18, the normally open switch valve I 19, the normally closed switch valve I 20, the normally open switch valve II 21, and the normally closed switch valve II 22 all adopt high-frequency switch valves. In the unmanned steering mode, the proportional directional valve 18 outputs control hydraulic oil to the flow amplifier 11 instead of the steering gear 5 in the manual steering mode. The left, middle, and right positions of the proportional directional valve 18 respectively correspond to the left steering, non-steering, and right steering conditions of the steering gear 5, so as to realize the steering action in the unmanned steering mode.

[0060] When the dump truck is in a non-steering condition, the normally open switch valve Ⅰ19, the normally closed switch valve Ⅰ20, the normally open switch valve Ⅱ21, and the normally closed switch valve Ⅱ22 are all de-energized, and the left and right control oil circuits of the proportional reversing valve 18 are freely connected to the hydraulic oil tank 25 through the right position of the normally open switch valve Ⅱ21 and the left position of the normally open switch valve Ⅰ19 respectively. At the same time, under the action of the control springs on the left and right sides of the proportional reversing valve 18, the proportional reversing valve 18 is kept in the middle position to work, and the hydraulic oil output by the hydraulic pump 1 reaches the priority valve 12 through the HP port of the flow amplifier 11. Regardless of whether the priority valve 12 is in the left position or the right position, the hydraulic oil output by the hydraulic pump 1 reaches the priority valve 12. Whether the proportional reversing valve 18 is in the middle position, the P port of the electric control steering valve 23 is not connected with the L, R, T, and LS ports of the electric control steering valve 23. The L, R, and LS oil ports of the proportional reversing valve 18 are connected with the T port of the flow amplifier through the T port of the proportional reversing valve 23. At this time, the L port and the R port of the converging valve 26 are not connected. There is control oil from the proportional reversing valve 18, so all the oil ports on the converging valve 26 are in the cut-off state at this time, and the flow amplifier T port is connected to the hydraulic oil tank 25 through the flow amplifier HT port. Since the pressure of the control oil chamber on the left side of the priority valve 12 is the same as the pressure output by the hydraulic pump 1, the control oil chamber on the right side of the priority valve 12 is connected to the hydraulic oil tank 25 through the LS port, and the thrust of the control spring on the right side of the priority valve 12 is much smaller than the thrust generated by the control oil chamber on the left side of the priority valve 12, the priority valve 12 moves right under the action of the hydraulic oil in the control oil chamber on the left side and works in the left position. When the priority valve When 12 is in the left position, the hydraulic oil output by the priority valve 12 is cut off at the P port of the electric control steering valve 23 and at the EF port of the flow amplifier 11. Since the normally closed switch valve Ⅰ20 and the normally closed switch valve Ⅱ22 are both closed, the hydraulic oil output to the P1 port of the electric control steering valve 23 through the mode switching valve 4 is cut off. At this point, the hydraulic oil output by the hydraulic pump 1 is in a cut-off state at the P port, P1 port of the electric control steering valve 23 and the EF port of the flow amplifier 11. The hydraulic pump 1 is in a high-pressure and small-displacement state, and the hydraulic steering system is in a high-pressure and small-displacement standby state.

[0061] When the dump truck needs to turn left, the controller 15 gives a left-turning instruction, causing the normally closed switch valve II 22 and the normally open switch valve II 21 to be energized, and the normally open switch valve I 19 and the normally closed switch valve I 20 not to be energized. At this time, the normally closed switch valve II 22 and the normally open switch valve I 19 are in the left-position connected state, and the normally open switch valve II 21 and the normally closed switch valve I 20 are in the left-position closed state. The hydraulic oil at the P1 port of the electro-hydraulic steering valve 23 reaches the left control oil chamber of the proportional directional valve 18 through the left position of the normally closed switch valve II 22. The right control oil chamber of the proportional directional valve 18 is connected to the hydraulic oil tank 25 through the left position of the normally open switch valve I 19 and the T port of the electro-hydraulic steering valve 23. Thus, the hydraulic oil in the left control oil chamber of the proportional directional valve 18 pushes the proportional directional valve 18 to move to the right and work in the left position. Different displacement amounts correspond to different opening degrees, so that the proportional directional valve 18 can output hydraulic oil with different flow rates. When the proportional directional valve 18 works in the left position, the P port of the electro-hydraulic steering valve 23 is connected to the L port, and the hydraulic oil at the P port of the electro-hydraulic steering valve 23 can flow to the L port. At the same time, due to the existence of the shuttle valve 16, the L port of the electro-hydraulic steering valve 23 is connected to the LS port. The L port and LS port of the electro-hydraulic steering valve 23 are respectively connected to the L port and LS port of the directional valve 7. The hydraulic oil passes through the L port and LS port of the directional valve 7 and is respectively connected to the L port and LS port of the flow amplifier 11. Under the action of the hydraulic oil at the L port of the flow amplifier 11, the P port and L port of the confluence valve 26 are both connected to the CL port of the confluence valve 26, and then connected to the CL port of the flow amplifier. At the same time, the hydraulic oil at the LS port of the flow amplifier 11 reaches the right control oil port of the priority valve 12. The left control oil port of the priority valve 12 is connected to the P port of the flow amplifier. Since the thrust of the right control oil of the priority valve plus the thrust of the right spring is greater than the thrust of the left control oil of the priority valve 12, the priority valve 12 moves to the left, and the priority valve 12 works in the right position. Since the priority valve 12 is in the right position, at this time, the hydraulic oil from the HP port of the flow amplifier 11 can only be supplied to the steering gear 5 and the flow amplifier 11 through the priority valve 12 and cannot be supplied to the EF port of the flow amplifier 11. At this time, the priority valve 12 allows the hydraulic oil from the hydraulic pump 1 to pass through in a large flow rate. To sum up, when the controller 15 gives a left-turning instruction, all the hydraulic oil output by the hydraulic pump 1 is supplied to the CL port of the flow amplifier 11. Since the CL port is connected to the steering cylinder 9, at this time, the hydraulic pump 1 switches from the high-pressure small-displacement state without steering action to the high-pressure large-displacement state to meet the oil supply demand of the steering cylinder 9. So far, the large-flow hydraulic oil output by the hydraulic pump 1 passes through the flow amplifier 11 and the electro-hydraulic steering valve 23 and is all supplied to the steering cylinder 9. The steering cylinder 9 is mechanically connected to the dump truck tire, so the action of the steering cylinder 9 drives the dump truck tire to rotate. At this time, the piston rod of the left steering cylinder 9.1 retracts, and the piston rod of the right steering cylinder 9.2 extends, thus realizing the left-turning action.The controller 15 monitors the signal of the displacement sensor II 17 in real time to judge the displacement of the proportional directional valve 18. When the displacement of the proportional directional valve 18 reaches the predetermined position, the normally open switch valve I 19 is energized and in the right-position closed state, the normally open switch valve II 21 is energized and in the left-position closed state, the normally closed switch valve I 20 is not energized and in the left-position closed state, and the normally closed switch valve II 22 is not energized and in the right-position closed state. At this time, the control oil circuits on both the left and right sides of the proportional directional valve 18 are all cut off, and the proportional directional valve 18 will maintain the predetermined displacement position and continuously perform the left-turning action.

[0062] When the left-turning condition of the dump truck is released, the normally open switch valve I 19, the normally closed switch valve I 20, the normally open switch valve II 21, and the normally closed switch valve II 22 are all not energized. The control oil circuits on both the left and right sides of the proportional directional valve 18 are respectively and freely communicated with the hydraulic oil tank 25 through the right position of the normally open switch valve II 21 and the left position of the normally open switch valve I 19. The hydraulic oil at the P1 port of the electro-hydraulic steering valve 23 is cut off at the right position of the normally closed switch valve II 22 and the left position of the normally closed switch valve I 20. At the same time, under the action of the control springs on both the left and right sides of the proportional directional valve 18, the proportional directional valve 18 returns to the middle position to work, and the dump truck returns to the non-steering condition.

[0063] When the dump truck needs to turn right, the controller 15 gives a right turn command, so that the normally closed switch valve II22 and the normally open switch valve II21 are not energized, and the normally open switch valve I19 and the normally closed switch valve I20 are energized. At this time, the normally closed switch valve II22 and the normally open switch valve I19 are in the right position closed state, and the normally open switch valve II21 and the normally closed switch valve I20 are in the right position connected state. The hydraulic oil at the P1 port of the electric control steering valve 23 passes through the normally closed switch valve I20 right position to the right control oil chamber of the proportional reversing valve 18, and the left control oil chamber of the proportional reversing valve 18 is connected to the hydraulic oil tank 25 through the T port of the electric control steering valve 23 through the right position of the normally open switch valve II21. The proportional reversing valve 18 is pushed to move to the left and works in the right position. Different displacements correspond to different openings, so that the proportional reversing valve 18 can output hydraulic oil of different flow rates. When the proportional reversing valve 18 works in the right position, the P port of the electric control steering valve 23 is connected with the R port, and the hydraulic oil of the P port of the electric control steering valve 23 can flow to the R port. At the same time, due to the existence of the shuttle valve 16, the R port of the electric control steering valve 23 is connected with the LS port, and the R port and LS port of the electric control steering valve 23 are respectively connected with the R port and LS port of the reversing valve 7. The hydraulic oil passes through the R port and LS port of the reversing valve 7 and is respectively connected with the R port and LS port of the flow amplifier 11. Under the action of the hydraulic oil of the R port of the flow amplifier 11, the P port of the converging valve 26 The R port is connected to the CR port of the converging valve 26, and then to the CR port of the flow amplifier 11. At the same time, the hydraulic oil of the LS port of the flow amplifier 11 reaches the right control oil port of the priority valve 12, and the left control oil port of the priority valve 12 is connected to the P port of the flow amplifier. Since the control oil thrust of the right side of the priority valve plus the right spring thrust is greater than the control oil thrust of the left side of the priority valve 12, the priority valve 12 moves to the left and the priority valve 12 is in the right position. Since the priority valve 12 is in the right position, the hydraulic oil from the HP port of the flow amplifier 11 can only be supplied to the steering gear 5 and the flow amplifier 11 through the priority valve 12, and cannot be supplied to the EF port of the flow amplifier 11. At this time, the priority valve 12 allows the hydraulic oil from the hydraulic pump 1 to The pressurized oil passes through in large flow. In summary, when the controller 15 gives a right turn command, the hydraulic oil output by the hydraulic pump 1 is all supplied to the CR port of the flow amplifier 11. Since the CR port is connected to the steering cylinder 9, the hydraulic pump 1 switches from a high-pressure, small-displacement state without steering action to a high-pressure, large-displacement state to meet the oil supply demand of the steering cylinder 9. At this point, the large-flow hydraulic oil output by the hydraulic pump 1 is all supplied to the steering cylinder 9 through the flow amplifier 11 and the electronically controlled steering valve 23. The steering cylinder 9 is mechanically connected to the dump truck tire, so the steering cylinder 9 moves to drive the dump truck tire to rotate. At this time, the piston rod of the left steering cylinder 9.1 extends, and the piston rod of the right steering cylinder 9.2 retracts, thereby realizing the right steering action.The controller 15 monitors the signal of the displacement sensor II 17 in real time to judge the displacement of the proportional directional valve 18. When the displacement of the proportional directional valve 18 reaches the predetermined position, the normally open switch valve I 19 is energized and in the right-position closed state, the normally open switch valve II 21 is energized and in the left-position closed state, the normally closed switch valve I 20 is not energized and in the left-position closed state, and the normally closed switch valve II 22 is not energized and in the right-position closed state. At this time, the control oil circuits on both the left and right sides of the proportional directional valve 18 are all cut off, and the proportional directional valve 18 will maintain the predetermined displacement position and continuously perform the right-turning action.

[0064] When the right-turning condition of the dump truck is released, the normally open switch valve I 19, the normally closed switch valve I 20, the normally open switch valve II 21, and the normally closed switch valve II 22 are all not energized. The control oil circuits on both the left and right sides of the proportional directional valve 18 are respectively and freely connected to the hydraulic oil tank 25 through the right position of the normally open switch valve II 21 and the left position of the normally open switch valve I 19. The hydraulic oil at the P1 port of the electro-hydraulic steering valve 23 is cut off at the right position of the normally closed switch valve II 22 and the left position of the normally closed switch valve I 20. At the same time, under the action of the control springs on both the left and right sides of the proportional directional valve 18, the proportional directional valve 18 returns to the middle position to work, and the dump truck returns to the non-steering condition.

[0065] Emergency steering mode:

[0066] To ensure the safety of vehicle driving, the priority of the manual steering mode is higher than that of the unmanned steering mode. When the dump truck is in the unmanned steering mode, if an emergency occurs and the driver needs to take over the steering action of the dump truck, that is, the vehicle needs to switch to the manual steering mode. At this time, the driver can automatically exit the unmanned steering mode by operating the steering wheel 24. Its working principle is that in the unmanned steering mode, both the angle sensor 6 and the steering gear 5 remain stationary. When the driver operates the steering wheel 24 in the unmanned steering mode, it will drive the angle sensor 6 and the steering gear 5 to move synchronously. At this time, the angle sensor 6 will send a signal to the controller 15. After receiving the signal from the angle sensor 6 in the unmanned steering mode, the controller 15 will immediately switch the mode switching valve 4, the normally open switch valve I 19, the normally closed switch valve I 20, the normally open switch valve II 21, and the normally closed switch valve II 22 to the de-energized state. When the mode switching valve 4 is de-energized, the mode switching valve 4 is in the right-position working state under the action of the right-side spring. The left control oil chamber of the reversing valve 7 is connected to the hydraulic oil tank 25 through the right position of the mode switching valve 4. Under the push of the right-side spring of the reversing valve 7, the reversing valve 7 moves to the left, and the hydraulic oil in the left control oil chamber returns to the hydraulic oil tank 25. The reversing valve 7 is in the right-position working state, and the steering gear 5 is normally connected to the flow amplifier 11 through the right position of the reversing valve 7. The steering gear returns to normal operation, and the vehicle enters the manned steering mode. The driver can realize the steering action by turning the steering wheel 24.

[0067] The unmanned full-hydraulic steering system and its usage method for mining dump trucks of the present invention are applicable to full-hydraulic steering systems, that is, there is no mechanical connection between the steering wheel and the steering tires, and the steering tires are completely driven by steering cylinders; a constant-pressure variable plunger pump is adopted to reduce the standby power of the hydraulic system under non-steering conditions and reduce energy loss; the cylinder stroke sensor is built into the steering cylinder, not affected by the harsh working conditions in the mining area, ensuring working reliability; the unmanned steering control uses high-speed on-off valves to ensure the response speed; the unmanned steering direction valve uses proportional reversing valves to ensure the response accuracy; the unmanned steering system can reduce the labor intensity of the driver and improve production efficiency; the manual steering mode has the highest priority to ensure that the steering wheel is always in a normal operating state, vehicle safety and the driver's full control over the steering action.

[0068] Finally, it should be noted that the above are only preferred examples of the present invention for patents, and are not used to limit the present invention for patents. Although the present invention for patents has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention for patents shall be included within the protection scope of the present invention for patents.

Claims

1. Method for using unmanned full-hydraulic steering system of mine dump truck, characterized in that: It includes a hydraulic pump (1). The oil outlet end of the hydraulic pump (1) is connected to a steering cylinder (9) through a flow amplifier (11). The steering cylinder (9) includes a left steering cylinder (9.1) and a right steering cylinder (9.2). The flow amplifier (11) is connected to a steering gear (5) and an electronically controlled steering valve (23) through a reversing valve (7). Both ends of the reversing valve (7) are respectively connected to a mode switching valve (4) and a displacement sensor I (8). The mode switching valve (4) is arranged at the oil outlet of the hydraulic pump (1). The displacement sensor I (8) is connected to a controller (15); The flow amplifier (11) includes a priority valve (12) and a confluence valve (26). The P, L, R, and LS oil ports of the flow amplifier (11) are connected to the P, L, R, and LS oil ports of the steering gear (5) and the electronically controlled steering valve (23) through the reversing valve (7); The steering gear (5) is rigidly connected to a corner sensor (6) and a steering wheel (24); The electronically controlled steering valve (23) includes a control valve group, a proportional reversing valve (18), and a shuttle valve (16). The control valve group is connected to both ends of the electronically controlled steering valve (23). The shuttle valve (16) is arranged at the oil outlet end of the proportional reversing valve (18) and is connected to the L, R, and LS oil ports of the electronically controlled steering valve (23); The controller (15) is further connected to a corner sensor (6), a stroke sensor (10), a vehicle speed sensor (13), a GPS signal (14), and a displacement sensor II (17). The stroke sensor (10) is arranged on the left steering cylinder (9.1) and the right steering cylinder (9.2). The displacement sensor II (17) is arranged at the control end of the electronically controlled steering valve (23); It includes a manual steering mode, an unmanned steering mode, and an emergency steering mode, The steering operation method of the manual steering mode is as follows: S1. The mode switching valve (4) is not energized, and the controller (15) does not participate in the steering action; S2. The reversing valve (7) is in the initial working position, and the flow amplifier (11) is connected to the steering gear (5); S3. The driver turns the steering wheel (24), and the steering wheel (24) drives the corner sensor (6) and the steering gear (5) to rotate synchronously; S4. Under the action of the steering gear (5), the P port of the flow amplifier (11) is connected to the L and LS ports or the P port is communicated with the LS and R ports; S5. The large-flow hydraulic oil output by the hydraulic pump (1) passes through the flow amplifier (11) and the steering gear (5) and is all supplied to the steering cylinder (9); S6. The steering cylinder (9) acts to drive the tires of the dump truck to rotate, and the piston rods of the left steering cylinder (9.1) and the right steering cylinder retract or extend to achieve the steering action; The steering operation method of the unmanned steering mode is as follows: T1. The mode switching valve (4) is energized, and the hydraulic oil is supplied to the control end of the reversing valve (7) through the mode switching valve (4). The reversing valve (7) switches the working position, and the flow amplifier (11) is connected to the proportional reversing valve (18); T2. The displacement sensor I (8) transmits the displacement signal of the reversing valve (7) to the controller (15), and the dump truck officially enters the unmanned steering mode; T3. The controller (15) monitors the operating states of the steering angle sensor (6), the stroke sensor (10), the vehicle speed sensor (13), the GPS signal (14), and the displacement sensor II (17) in real time; T4. When the dump truck needs to turn, the controller (15) gives a steering command, controls the proportional reversing valve (18) to act and switch to different working positions through the control valve group, so that the P port of the flow amplifier (11) is connected to the L and LS ports or the P port is communicated with the LS and R ports; T5. The large-flow hydraulic oil output by the hydraulic pump (1) passes through the flow amplifier (11) and the proportional reversing valve (18) and is all supplied to the steering cylinder (9); T6. The controller (15) monitors the signal of the displacement sensor II (17) in real time to judge the displacement of the proportional reversing valve (18); T7. When the displacement of the proportional reversing valve (18) reaches the predetermined position, the controller (15) controls the control valve group to cut off all the control oil circuits on the left and right sides of the proportional reversing valve (18), and the proportional reversing valve (18) maintains the predetermined displacement position and continues the steering action; T8. When the dump truck releases the steering condition, the control valve group is de-energized. When the two ends of the proportional reversing valve (18) are depressurized and then return to the neutral position to work, the dump truck returns to the non-steering condition; The operation method of the emergency steering mode is as follows: E1. When the driver operates the steering wheel (24) in the unmanned steering mode, the steering wheel (24) drives the steering angle sensor (6) and the steering gear (5) to move synchronously; E2. The steering angle sensor (6) sends a signal to the controller (15); E3. The controller (15) controls the mode switching valve (4) and the control valve group to be de-energized; E4. The reversing valve (7) resets, the flow amplifier (11) is connected to the steering gear (5), and the vehicle enters the manned steering mode.

2. The usage method of the fully hydraulic steering system for driverless mining dump trucks according to claim 1, characterized in that: The priority valve (12) is a two-position three-way hydraulic control valve. The two hydraulic control ends of the priority valve (12) are respectively connected to the P and LS oil ports of the flow amplifier (11), and a spring is provided at the control end connected to the LS oil port.

3. The usage method of the unmanned full-hydraulic steering system for mining dump trucks according to claim 1, characterized in that: The flow combining valve (26) is provided with P, L, R, T, CL, and CR oil ports. The P, L, R, and T oil ports of the flow combining valve (26) are connected to the P, L, R, and T oil ports of the flow amplifier (11), and the CL and CR oil ports are connected to the left steering cylinder (9.1) and the right steering cylinder (9.2).

4. The usage method of the fully hydraulic steering system for driverless mining dump trucks according to claim 1, characterized in that: The reversing valve (7) is a two-position twelve-way hydraulic control reversing valve.

5. The usage method of the unmanned full-hydraulic steering system for mining dump trucks according to claim 1, characterized in that: The mode switching valve (4) is a two-position three-way electromagnetic reversing valve. The mode switching valve (4) is connected to the oil outlet end of the hydraulic pump (1) through the overflow valve (3) and the pressure reducing valve (2).

6. The method for using the fully hydraulic steering system for driverless mining dump trucks according to claim 1, characterized in that: The control valve group includes a normally open switch valve I (19), a normally closed switch valve I (20), a normally open switch valve II (21), and a normally closed switch valve II (22). The normally open switch valve I (19) and the normally closed switch valve I (20) are arranged in parallel at one end of the electro-hydraulic steering valve (23), and the normally open switch valve II (21) and the normally closed switch valve II (22) are arranged in parallel at the other end of the electro-hydraulic steering valve (23).

7. The method for using the fully hydraulic steering system for driverless mining dump trucks according to claim 6, characterized in that: The normally open switching valve I (19), normally closed switching valve I (20), normally open switching valve II (21) and normally closed switching valve II (22) are all two-position two-way high-frequency switching valves.

8. The usage method of the driverless full-hydraulic steering system for mining dump trucks according to claim 1, characterized in that: The proportional direction valve (18) is a three-position five-way hydraulically controlled direction valve. The oil inlet end of the proportional direction valve (18) is connected to the P port of the electro-hydraulic steering valve (23), and the oil outlet end of the proportional direction valve (18) is connected to the L and R ports of the electro-hydraulic steering valve (23) through a shuttle valve (16).

9. The usage method of the unmanned full-hydraulic steering system for mining dump trucks according to claim 1, characterized in that: When the P port of the flow amplifier (11) is connected to the L and LS ports, the P port and the L port of the flow combining valve (26) are both communicated with the CL port of the flow combining valve (26). At the same time, the hydraulic oil at the LS port of the flow amplifier (11) reaches one side control oil port of the priority valve (12), and the other side control oil port of the priority valve (12) is communicated with the P port of the flow amplifier (11). The control hydraulic oil pressures on both sides of the priority valve (12) are the same. Under the thrust of the spring on one side, the priority valve (12) displaces and switches to the working position.

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