Hydraulic steering system and control method thereof and dump truck

Abstract

The application provides a hydraulic steering system, a control method thereof and a dump truck. The hydraulic steering system comprises a hydraulic oil tank, a steering gear, a steering oil cylinder, a main reversing circuit and an emergency reversing circuit. The main reversing circuit comprises a first oil inlet pipeline arranged between an oil inlet of the steering gear and the hydraulic oil tank, and a first oil return pipeline arranged between an oil outlet of the steering gear and the hydraulic oil tank. A main steering pump is arranged on the first oil inlet pipeline. The emergency reversing circuit comprises a second oil inlet pipeline connected in parallel with the first oil inlet pipeline, and the first oil return pipeline. The second oil inlet pipeline is sequentially provided with an emergency steering pump, a liquid filling valve and an accumulator. The emergency steering pump can charge the accumulator with liquid through the liquid filling valve. The accumulator can supply oil to the oil inlet of the steering gear through the second oil inlet pipeline. The steering gear is connected with the steering oil cylinder, and is used for supplying hydraulic oil to the steering oil cylinder to drive the steering oil cylinder to act. The hydraulic steering system can improve the rapidity of emergency steering response.

Description

Technical Field

[0001] This invention relates to the field of steering system technology, and particularly to a hydraulic steering system. The invention also relates to a control method for the aforementioned hydraulic steering system. Furthermore, the invention also relates to a dump truck equipped with the aforementioned hydraulic steering system. Background Technology

[0002] Current hydraulic steering systems fall into two categories: one uses a high-pressure main steering motor pump paired with a high-pressure accumulator, and the other uses a high-pressure motor pump paired with a low-pressure emergency steering pump. Both have the following drawbacks: With a high-pressure main steering motor pump and a high-pressure accumulator, if the high-pressure main steering motor pump fails for any reason, the high-pressure accumulator releases its stored hydraulic energy, eventually becoming ineffective after reaching a certain pressure. However, to achieve a certain duration of operation, a larger accumulator is required, which is limited by overall machine space and cost.

[0003] The high-voltage motor pump is paired with a low-voltage emergency steering pump. If the high-voltage main steering motor pump fails, the low-voltage emergency steering pump will start and provide hydraulic energy to the steering system. Since the energy of the low-voltage emergency steering pump is taken from the low-voltage battery, due to factors such as overall space and battery cost, the number of batteries is relatively small, the stored power is limited, the duration is short, the steering is slow, and continuous power supply will cause the battery to run out of power or be damaged. Summary of the Invention

[0004] In view of this, the present invention aims to provide a hydraulic steering system that can improve the speed of emergency steering response.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A hydraulic steering system includes a hydraulic oil tank, a steering gear, a steering cylinder, a main reversing circuit, and an emergency reversing circuit;

[0007] The main reversing circuit includes a first oil inlet pipe located between the oil inlet of the steering gear and the hydraulic oil tank, and a first oil return pipe located between the oil outlet of the steering gear and the hydraulic oil tank. The first oil inlet pipe is equipped with a main steering pump.

[0008] The emergency reversing circuit includes a second oil inlet line connected in parallel with the first oil inlet line, and a first oil return line. An emergency steering pump, a filling valve and an accumulator are sequentially provided on the second oil inlet line. The emergency steering pump can fill the accumulator with liquid and store energy through the filling valve. The accumulator can supply oil to the oil inlet of the steering gear through the second oil inlet line.

[0009] The steering gear is connected to the steering cylinder, and the steering gear is used to supply hydraulic oil to the steering cylinder to drive the steering cylinder to move.

[0010] Furthermore, the first oil inlet line is provided with a priority valve and a check valve. The priority valve is located between the main steering pump and the check valve, and the priority valve is used to unload and save energy of the main steering pump when the steering gear is not working.

[0011] Furthermore, a pressure relief oil circuit is connected in parallel to the first oil inlet pipe. One end of the pressure relief oil circuit is connected to the outlet end of the one-way valve, and the other end is connected to the hydraulic oil tank. An overflow device is provided on the pressure relief oil circuit.

[0012] Furthermore, a first pressure detection device is provided on the first oil inlet line and / or the second oil inlet line. The first pressure detection device is located close to the steering gear and is used to detect the oil pressure entering the oil inlet of the steering gear.

[0013] Furthermore, a control valve is provided on the second oil inlet pipeline. The control valve is located downstream of the accumulator and is used to open or close the second oil inlet pipeline.

[0014] Furthermore, a second pressure detection device is provided on the second oil inlet pipeline. The second pressure detection device is located between the control valve and the accumulator, and is used to detect the oil pressure at the oil port of the accumulator.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The hydraulic steering system of the present invention, through the setting of a main reversing circuit and an emergency reversing circuit, and the setting of a charging valve and an accumulator in the emergency reversing circuit, allows the emergency steering pump to charge the accumulator with liquid through the charging valve and store energy. Moreover, when the main reversing circuit fails to work properly, the accumulator can supply oil to the steering gear alone to drive the steering cylinder to move. Furthermore, the accumulator and the emergency steering pump can also supply oil to the steering gear at the same time, thereby improving the speed of emergency steering response.

[0017] Furthermore, the priority valve installed on the first oil inlet line can unload and save energy from the main steering pump when the steering gear is not in operation. The check valve prevents oil from flowing to the priority valve and main steering pump and causing pressure loss when the emergency steering pump is running. The pressure relief oil circuit and overflow device play a role in protecting system safety and determining system pressure. When the load pressure exceeds the overflow pressure set by the overflow device, the overflow pressure unloads the oil circuit system and protects the transmission components.

[0018] In addition, the first pressure detection device is used to detect the hydraulic pressure entering the steering gear inlet, i.e., to detect the steering line pressure. The control valve on the second hydraulic line facilitates the opening and closing of the second hydraulic line, and when the pressure in the main steering circuit is insufficient, the control valve opens the second hydraulic line, allowing the emergency steering pump to provide power to the steering gear. The second pressure detection device on the second hydraulic line is used to detect the accumulator pressure.

[0019] Another object of the present invention is to provide a control method for a hydraulic steering system as described above, the control method comprising:

[0020] The preset pressure of the first pressure detection device is A1, the preset pressure of the second pressure detection device is A2, and the set cut-off pressure of the filling valve is A3. When the hydraulic steering system is working normally, the following condition must be met: A1 < A2 < A3.

[0021] During driving, when the detected pressure a1 detected by the first pressure detection device is less than A1, the main steering pump works, controls the control valve to switch, controls the accumulator to work, and controls the emergency steering pump to work. The accumulator and the emergency steering pump simultaneously supply hydraulic oil to the steering gear inlet.

[0022] When the detection pressure a1 is still less than A1 after the emergency steering pump has circulated several times, a signal indicating a fault exists in the emergency reversing circuit is issued.

[0023] Furthermore, the control method also includes: during driving, if the detected pressure a1 is less than A1 and the main steering pump is not working, a signal indicating a fault exists in the main commutation circuit is issued.

[0024] Furthermore, during driving, when the detection pressure a2 detected by the second pressure detection device is less than A2, the emergency steering pump is controlled to work, and liquid is charged into the accumulator through the filling valve until the set cut-off pressure A3 is reached, at which point the emergency steering pump is unloaded. When the detection pressure a2 is greater than A2, the emergency steering pump stops working.

[0025] The control method for the hydraulic steering system described in this invention facilitates intelligent control of normal and emergency steering, and also facilitates intelligent identification of hydraulic steering system faults.

[0026] Another object of the present invention is to provide a dump truck equipped with the hydraulic steering system described above.

[0027] The dump truck of the present invention and the hydraulic steering system described above have the same beneficial effects as the prior art, which will not be repeated here. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0029] Figure 1 This is a schematic diagram of the hydraulic steering system described in an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram illustrating the connection between the steering gear and the steering cylinder according to an embodiment of the present invention.

[0031] Figure 3 This is a logic diagram of the control method for the hydraulic steering system according to an embodiment of the present invention;

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Hydraulic oil tank; 2. Main steering pump; 3. Emergency steering pump; 4. Priority valve; 5. Filling valve; 6. Accumulator; 7. Second pressure detection device; 8. Control valve; 9. Check valve; 11. First pressure detection device; 12. Controller; 13. Steering gear; 14. Steering cylinder; 15. Overflow device;

[0034] 10. First oil inlet line; 20. Second oil inlet line; 30. First oil return line; 40. Pressure relief line; 50. Second oil return line; 60. Third oil return line; 70. Feedback line. Detailed Implementation

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0036] In the description of this invention, it should be noted that the use of terms such as "upper," "lower," "inner," and "outer," indicating orientation or positional relationship, is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the use of terms such as "first" and "second" is also for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] Furthermore, in the description of this invention, unless otherwise explicitly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0038] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] This embodiment relates to a hydraulic steering system that can improve the speed of emergency steering response.

[0040] In terms of overall composition, such as Figure 1 As shown, the hydraulic steering system in this embodiment specifically includes a hydraulic oil tank 1, a steering gear 13, a steering cylinder 14, a main reversing circuit, and an emergency reversing circuit.

[0041] The main reversing circuit includes a first oil inlet pipe 10 located between the oil inlet of the steering gear 13 and the hydraulic oil tank 1, and a first oil return pipe 30 located between the oil outlet of the steering gear 13 and the hydraulic oil tank 1. A main steering pump 2 is installed on the first oil inlet pipe 10. The main steering pump 2 supplies oil from the hydraulic oil tank 1 to the oil inlet of the steering gear.

[0042] The emergency reversing circuit includes a second oil inlet line 20 connected in parallel with the first oil inlet line 10, and a first oil return line 30. An emergency steering pump 3, a charging valve 5, and an accumulator 6 are sequentially mounted on the second oil inlet line 20. The emergency steering pump 3 can charge the accumulator 6 with liquid through the charging valve 5, and the accumulator 6 can supply oil to the oil inlet of the steering gear 13 through the second oil inlet line 20. Furthermore, the emergency steering pump 3 also supplies oil from the hydraulic oil tank 1 to the oil inlet of the steering gear.

[0043] Furthermore, the steering gear 13 is connected to the steering cylinder 14, and the steering gear 13 is used to supply hydraulic oil to the steering cylinder 14 to drive the steering cylinder 14 to move.

[0044] At this time, by setting up a main reversing circuit and an emergency reversing circuit, the main reversing circuit and the emergency reversing circuit share the same first return oil line 30, making the structure simpler and more compact. Furthermore, a filling valve 5 and an accumulator 6 are set in the emergency reversing circuit, so that the emergency steering pump 3 fills the accumulator 6 with liquid through the filling valve 5. When the main reversing circuit cannot work properly, the accumulator 6 can supply oil to the steering gear 13 independently to drive the steering cylinder 14 to move. Moreover, the accumulator 6 and the emergency steering pump 3 can also supply oil to the steering gear at the same time, thereby improving the speed of emergency steering response.

[0045] For more details, please refer to [link / reference]. Figure 1 As shown, the first oil inlet line 10 is equipped with a priority valve 4 and a check valve 9. The priority valve 4 is located between the main steering pump 2 and the check valve 9, and the priority valve 4 is used to unload and save energy when the steering gear 13 is not working. The check valve 9 is provided to prevent oil from flowing to the priority valve 4 and the main steering pump 2 and causing pressure loss when the emergency steering pump 3 is running.

[0046] In practical implementation, the P port of the priority valve 4 is connected to the outlet of the main steering pump 2, the CF port of the priority valve 4 is connected to the inlet of the check valve 9, the FF port of the priority valve 4 is connected to the hydraulic oil tank 1 through the second return oil line, and the LD port of the priority valve 4 is connected to the LS port in the steering gear 13 through the feedback oil circuit 70. Thus, the priority valve 4 is configured to prioritize the supply of hydraulic fluid to the steering gear 13 when it is operating, and to achieve unloading and energy saving of the main steering pump 2 through feedback from the feedback oil circuit 70 when the steering gear 13 is not operating. The check valve is located downstream of the pilot valve 4, which can prevent hydraulic fluid from flowing to the priority valve 4 and the main steering pump 2 and causing pressure loss when the emergency steering pump is running.

[0047] In this embodiment, a pressure relief oil passage 40 is connected in parallel to the first oil inlet pipe 10. One end of the pressure relief oil passage 40 is connected to the outlet end of the one-way valve 9, and the other end is connected to the hydraulic oil tank 1. An overflow device 15 is provided on the pressure relief oil passage 40. The pressure relief oil passage 40 and the overflow device 15 serve to protect the system safety and determine the system pressure. When the load pressure exceeds the overflow pressure set by the overflow device 15, the overflow pressure unloads the oil circuit system, protecting the transmission components. Furthermore, in specific implementations, an overflow valve is preferably used as the overflow device.

[0048] See also Figure 1 As shown, in this embodiment, a first pressure detection device 11 is provided on the first oil inlet line 10 and the second oil inlet line 20. The first pressure detection device 11 is located close to the steering gear 13 and is used to detect the oil pressure entering the oil inlet of the steering gear 13. Preferably, the first pressure detection device 11 is a first pressure sensor.

[0049] In a preferred embodiment, one end of the first oil inlet pipe 10 and the second oil inlet pipe 20 are respectively connected to the hydraulic oil tank 1, and the other end converges to the same connecting pipe, which is then connected to the oil inlet of the steering gear 13. In this case, the first pressure detection device 11 is installed on the connecting pipe. Compared to a connection method where the device is solely connected to the steering gear oil inlet, this reduces the number of first pressure detection devices 11 required.

[0050] It is worth noting that, in addition to being installed on the connecting pipeline, the first pressure detection device 11 can also be installed only on the first oil inlet pipeline 10 or only on the second oil inlet pipeline 20. In this case, the first pressure detection device 11 can only detect the oil pressure entering the oil inlet of the steering gear 13 in the main steering circuit, or it can only detect the oil pressure entering the oil inlet of the steering gear 13 in the emergency circuit.

[0051] In this embodiment, a control valve 8 is provided on the second oil inlet line 20. The control valve 8 is located downstream of the accumulator 6 and is used to open or close the second oil inlet line 20. Specifically, the control valve 8 is preferably a normally closed electromagnetic directional valve. Preferably, the control valve 8 is connected to the controller 12, and the controller 12 controls the directional switching. When the directional switching occurs, the second oil inlet line 20 is open. At this time, the accumulator 6 can supply oil to the oil inlet of the steering gear 13. When the emergency steering pump 3 is started, the emergency steering pump 3 can also supply oil to the oil inlet of the steering gear 13.

[0052] In addition, in this embodiment, a second pressure detection device 7 is provided on the second oil inlet pipeline 20. The second pressure detection device 7 is located between the control valve 8 and the accumulator 6, and is used to detect the oil pressure at the oil port of the accumulator 6. When the pressure detected by the second pressure detection device 7 is lower than the set pressure of the accumulator 6, the emergency steering pump 3 is started to charge the accumulator 6 with liquid through the charging valve 5. When the pressure detected by the second pressure detection device 7 reaches the set pressure of the accumulator 6, the emergency steering pump 3 is stopped.

[0053] In this embodiment, by setting the second detection device 7 and the controller 12, and by utilizing the automatic low-pressure filling and high-pressure unloading functions of the filling valve 5, the accumulator 6 can be automatically filled. When the set filling pressure of the accumulator 6 is reached, the emergency motor pump 3 is automatically switched to unload and power off.

[0054] In addition, combined Figure 1 and Figure 2 As shown, in this embodiment, the steering gear 13 has a steering control valve. The steering control valve is a three-position seven-way reversing valve. The P port of the steering control valve is also the oil inlet of the steering gear 13. It is connected to the first oil inlet line 10 and the second oil inlet line 20. The T port of the steering control valve is connected to the first return line 30. The LS port of the steering control valve is connected to the oil port of the priority valve 4 through the feedback oil line 70.

[0055] The following is combined Figure 1 and Figure 3 The specific working process of the hydraulic steering system in this embodiment will be described in detail.

[0056] The preset pressure of the first pressure detection device 11 is A1, the preset pressure of the second pressure detection device 7 is A2, and the set cut-off pressure of the filling valve 5 is A3. When the hydraulic steering system is working normally, the following condition must be met: A1 < A2 < A3.

[0057] When the main steering circuit is working, the main steering pump 2 draws hydraulic fluid from the hydraulic oil tank 1. The fluid passes through the priority valve 4, the check valve 9, and the first pressure detection device 11, reaching the steering gear 13. The steering gear 13 rotates to supply hydraulic fluid to the steering cylinder 14, achieving left and right steering. The fluid flows back to the hydraulic oil tank 1 through the first return line 30. When the load pressure exceeds the set pressure of the relief device 15, the relief valve opens, unloading the fluid and protecting the transmission components.

[0058] When the pressure in the main steering circuit is lower than the preset pressure of the first pressure detection device 11, that is, when the detection pressure a1 of the first pressure detection device 11 is less than the preset pressure A1, the main steering pump 2 does not rotate. At this time, the controller 12 sends a fault signal, such as checking whether there is a fault in the motor, wiring harness, or program of the main steering pump 2.

[0059] When the detected pressure a1 of the first pressure detection device 11 is less than the preset pressure A1, the main steering pump 2 rotates. At this time, the controller 12 controls the control valve 8 to switch, and the accumulator 6 supplies hydraulic oil to the oil inlet of the steering gear 13. Simultaneously, the controller 12 controls the emergency steering pump 3 to operate at its highest speed, supplying hydraulic oil to the oil inlet of the steering gear 13. When the detected pressure a1 of the first pressure detection device 11 is greater than the preset pressure A1, the accumulator 6 and the emergency steering pump 3 jointly supply hydraulic oil to the oil inlet of the steering gear 13. After the emergency steering pump 3 has cycled several times, if the detected pressure a1 of the first pressure detection device 11 is still less than the preset pressure A1, the controller 12 sends a signal indicating a fault in the emergency switching circuit, such as checking for faults in the filling valve 5, control valve 8, accumulator 6, or corresponding pipelines.

[0060] When the detection pressure a1 detected by the first pressure detection device 11 is greater than the preset pressure A1, the steering gear 13 cannot turn. At this time, the controller 12 sends a signal that there is a fault in the main reversing circuit, such as checking whether there is a fault in the steering gear 13, priority valve 4, check valve 9 or corresponding pipeline.

[0061] When the second pressure detection device 7 detects that the detection pressure a2 at the oil port of the accumulator 6 is less than A2, the controller 12 controls the emergency steering pump 3 to work, charging the accumulator 6 with hydraulic oil through the charging valve 5 until the set cut-off pressure A3 of the charging valve 5 is reached. The charging valve 5 then unloads the emergency steering pump 3 through internal pilot control. When the detection pressure a2 detected by the second pressure detection device 7 is greater than A2, the controller 12 controls the emergency steering pump 3 to stop rotating, so that the accumulator 6 always maintains a certain pressure and flow of hydraulic oil. During the entire charging process, the control valve 8 is not energized, and the second oil inlet pipe 20 is in the disconnected state. Example 2

[0062] This embodiment relates to a control method for the hydraulic steering system described in Embodiment 1, combined with... Figure 3 As shown, the control method includes: the preset pressure of the first pressure detection device 11 is A1, the preset pressure of the second pressure detection device 7 is A2, the set cut-off pressure of the filling valve 5 is A3, and when the hydraulic steering system is working normally, it satisfies: A1 < A2 < A3.

[0063] During operation, when the detected pressure a1 detected by the first pressure detection device 11 is less than A1, the main steering pump 2 operates, controlling the control valve 8 to switch directions and controlling the accumulator 6 to operate. Simultaneously, the emergency steering pump 3 operates, and the accumulator 6 and emergency steering pump 3 simultaneously supply hydraulic oil to the oil inlet of the steering gear 13. If, after the emergency steering pump 3 has circulated several times, the detected pressure a1 is still less than A1, a signal indicating a fault in the emergency reversing circuit is issued.

[0064] In addition, during driving, the detection pressure a1 detected by the first pressure detection device 11 is less than A1, and the main steering pump 2 does not work, sending a signal that there is a fault in the main reversing circuit.

[0065] In addition, during driving, when the detection pressure a2 detected by the second pressure detection device 7 is less than A2, the emergency steering pump 3 is controlled to work, and liquid is charged into the accumulator 6 through the filling valve 5 until the set cut-off pressure A3 is reached, the emergency steering pump 3 is unloaded, and when the detection pressure a2 is greater than A2, the emergency steering pump 3 stops working.

[0066] Please refer to the above description of the specific working process of the hydraulic steering system.

[0067] The control method of the hydraulic steering system in this embodiment can facilitate intelligent control of normal steering and emergency steering, and also facilitates intelligent identification of hydraulic steering system faults, with excellent performance.

[0068] Furthermore, this embodiment also relates to a dump truck equipped with the hydraulic steering system described in Embodiment 1. Preferably, the dump truck is a pure electric off-highway wide-body dump truck.

[0069] The dump truck in this embodiment, by applying the hydraulic steering system of Embodiment 1, can realize automatic energy replenishment and cut-off control of the accumulator 6. The accumulator 6 and the emergency steering pump 3 simultaneously supply oil to the steering gear 13, which can facilitate intelligent control of normal steering and emergency steering, and has a fast response, long endurance, and ensures safety and energy saving, thus having a very good usage effect.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method for a hydraulic steering system, characterized in that: The hydraulic steering system includes a hydraulic oil tank (1), a steering gear (13), a steering cylinder (14), a main reversing circuit, and an emergency reversing circuit; The main reversing circuit includes a first oil inlet pipe (10) located between the oil inlet of the steering gear (13) and the hydraulic oil tank (1), and a first oil return pipe (30) located between the oil outlet of the steering gear (13) and the hydraulic oil tank (1). The first oil inlet pipe (10) is equipped with a main steering pump (2). The emergency reversing circuit includes a second oil inlet pipe (20) connected in parallel with the first oil inlet pipe (10) and a first oil return pipe (30). An emergency steering pump (3), a filling valve (5) and an accumulator (6) are sequentially provided on the second oil inlet pipe (20). The emergency steering pump (3) fills the accumulator (6) with liquid through the filling valve (5) and the accumulator (6) can supply oil to the oil inlet of the steering gear (13) through the second oil inlet pipe (20). The steering gear (13) is connected to the steering cylinder (14), and the steering gear (13) is used to provide hydraulic oil to the steering cylinder (14) to drive the steering cylinder (14) to move; A first pressure detection device (11) is provided on the first oil inlet pipe (10) and / or the second oil inlet pipe (20). The first pressure detection device (11) is located close to the steering gear (13) and is used to detect the oil pressure entering the oil inlet of the steering gear (13). The second oil inlet pipeline (20) is provided with a control valve (8), which is located downstream of the accumulator (6) and is used to open or close the second oil inlet pipeline (20). The second oil inlet pipeline (20) is provided with a second pressure detection device (7), which is located between the control valve (8) and the accumulator (6), and the second pressure detection device (7) is used to detect the oil pressure at the oil port of the accumulator (6); The control method includes: The preset pressure of the first pressure detection device (11) is A1, the preset pressure of the second pressure detection device (7) is A2, and the set cut-off pressure of the filling valve (5) is A3. When the hydraulic steering system is working normally, it satisfies: A1 < A2 < A3. During driving, when the detection pressure a1 detected by the first pressure detection device (11) is less than A1, the main steering pump (2) works, controls the control valve (8) to switch, and controls the accumulator (6) to work, while controlling the emergency steering pump (3) to work. The accumulator (6) and the emergency steering pump (3) simultaneously supply hydraulic oil to the oil inlet of the steering gear (13). When the emergency steering pump (3) cycles several times, and the detection pressure a1 is still less than A1, a signal indicating a fault exists in the emergency reversing circuit is issued. During driving, when the detection pressure a2 detected by the second pressure detection device (7) is less than A2, the emergency steering pump (3) is controlled to work and the accumulator (6) is filled with liquid through the filling valve (5) until the set cut-off pressure A3 is reached. The emergency steering pump (3) is unloaded. When the detection pressure a2 is greater than A2, the emergency steering pump (3) stops working.

2. The control method for the hydraulic steering system according to claim 1, characterized in that, The control method further includes: During driving, if the detection pressure a1 is less than A1 and the main steering pump (2) does not work, a signal indicating a fault exists in the main commutation circuit will be issued.

3. A hydraulic steering system based on the control method of the hydraulic steering system according to claim 1, characterized in that: The first oil inlet pipeline (10) is provided with a priority valve (4) and a check valve (9). The priority valve (4) is located between the main steering pump (2) and the check valve (9). The priority valve (4) is used to unload and save energy of the main steering pump (2) when the steering gear (13) is not working.

4. The hydraulic steering system according to claim 3, characterized in that: The first oil inlet pipeline (10) is connected in parallel with a pressure relief oil line (40). One end of the pressure relief oil line (40) is connected to the outlet end of the one-way valve (9), and the other end is connected to the hydraulic oil tank (1). An overflow device (15) is provided on the pressure relief oil line (40).

5. A dump truck, characterized in that: The dump truck is equipped with the hydraulic steering system as described in claim 3 or 4.

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