Steering priority hydraulic system with mechanical and electro-hydraulic steering control for industrial vehicles

Abstract

The present application discloses a steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles, the system comprising a fuel tank, a multi-way valve assembly, a steering control valve assembly and a steering oil cylinder; the multi-way valve assembly is connected to the fuel tank, the multi-way valve assembly is connected to the steering control valve assembly, the steering control valve assembly is connected to the steering oil cylinder; the steering control valve assembly comprises a first reversing valve, a second reversing valve and a third reversing valve connected in sequence; the system further comprises a steering signal valve, the steering signal valve is connected to the third reversing valve, the steering signal valve is connected to the multi-way valve assembly; the system further comprises a steering gear, the steering gear is connected to the steering control valve assembly, the steering gear is connected to the second reversing valve and the steering signal valve, and the steering gear is connected to the steering oil cylinder. The above hydraulic system can realize automatic electro-hydraulic steering control, and in the process of automatic electro-hydraulic steering control, manual steering can be realized, and the priority of manual steering can be guaranteed to be the highest, thereby greatly improving the safety of vehicle operation.

Description

Technical Field

[0001] The present application relates to the field of hydraulic control technology, and in particular to a steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles. Background Art

[0002] At present, the steering function of an internal combustion forklift is achieved by connecting a mechanical steering column to a steering wheel, and the mechanical steering column is mechanically connected to a steering gear, and oil is supplied to the steering cylinder through the steering gear, thereby achieving the steering function. However, the steering function in the prior art is achieved by connecting a mechanical operating mechanism to a steering gear, and the steering wheel must be manually operated to achieve the steering function. Therefore, according to the application requirements of the forklift, it is necessary to provide a hydraulic system that can achieve automatic control or remote control in a timely manner. Summary of the invention

[0003] The purpose of the present application is to provide a steering priority hydraulic system with controllable mechanical and electro-hydraulic steering for industrial vehicles, which can realize automatic steering control and ensure the priority of manual steering.

[0004] To achieve the above-mentioned purpose, the present application provides a steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles, comprising a fuel tank, a multi-way valve assembly, a steering control valve assembly and a steering cylinder;

[0005] The P port of the multi-way valve assembly is connected to the oil tank, the CF port of the multi-way valve assembly is connected to the P port of the steering control valve assembly, and the L port and the R port of the steering control valve assembly are connected to the A chamber and the B chamber of the steering cylinder respectively;

[0006] The steering control valve assembly comprises a first reversing valve, a second reversing valve and a third reversing valve, wherein the first reversing valve is connected to the P port of the steering control valve assembly, the second reversing valve is connected to the first reversing valve, the third reversing valve is connected to the second reversing valve, and the third reversing valve is connected to the L port and the R port of the steering control valve assembly;

[0007] The system further comprises a turn signal valve, wherein a P1 port of the turn signal valve is connected to a signal port of the third reversing valve, and an LS port of the turn signal valve is connected to an LS port of the multi-way valve assembly;

[0008] When the system receives a first steering signal, the first reversing valve is electrically reversed, and the pressure signal of the third reversing valve is transmitted to the multi-way valve assembly through the steering signal valve, and the multi-way valve assembly distributes oil through the P port of the steering control valve assembly, and the oil is successively delivered to the steering cylinder through the first reversing valve, the second reversing valve and the third reversing valve to achieve steering;

[0009] The system further comprises a steering gear, wherein the P port of the steering gear is connected to the P1 port of the steering control valve assembly, the LS port of the steering gear is connected to the signal port of the second reversing valve and the P2 port of the steering signal valve, and the L port and the R port of the steering gear are respectively connected to the A cavity and the B cavity of the steering cylinder;

[0010] When the system receives the second steering signal, the pressure signal generated by the LS port of the steering gear is transmitted to the signal port of the second reversing valve and the P2 port of the steering signal valve to reverse the second reversing valve, and to allow the oil in the oil tank to pass through the multi-way valve assembly and the P port of the steering control valve assembly, and then be delivered to the steering cylinder through the first reversing valve, the second reversing valve and the steering gear in sequence, thereby achieving steering.

[0011] Optionally, the multi-way valve assembly includes a steering priority valve, the oil inlet of the steering priority valve is connected to the oil tank, and the oil outlet of the steering priority valve is connected to the P port of the steering control valve assembly, for supplying a preset flow of oil in the oil tank through the P port of the steering control valve assembly.

[0012] Optionally, the multi-way valve assembly further includes a relief valve connected to the steering priority valve and the oil tank, and configured to ensure that the working pressure of the steering priority valve does not exceed a first preset value.

[0013] Optionally, the system further comprises a power assembly connected to the oil tank and configured to suck oil from the oil tank and supply the oil to the steering priority valve.

[0014] Optionally, an oil suction filter is connected between the power assembly and the oil tank.

[0015] Optionally, the system further comprises a safety valve connected to the LS port of the steering gear and the oil tank, and configured to ensure that the working pressure of the steering gear does not exceed a second preset value.

[0016] Optionally, a bidirectional hydraulic lock is connected between the third reversing valve and the steering cylinder.

[0017] Optionally, the first reversing valve is a two-position three-way electromagnetic reversing valve, the second reversing valve is a two-position three-way hydraulically controlled reversing valve, and the third reversing valve is a three-position five-way electrically-operated proportional reversing valve.

[0018] Optionally, the T-port of the steering gear is connected to the oil tank.

[0019] With respect to the above background technology, the steering priority hydraulic system with controllable mechanical and electro-hydraulic steering of industrial vehicles provided in the embodiment of the present application includes a fuel tank, a multi-way valve assembly, a steering control valve assembly and a steering cylinder. Among them, the P port of the multi-way valve assembly is connected to the fuel tank, the CF port of the multi-way valve assembly is connected to the P port of the steering control valve assembly, and the L port and R port of the steering control valve assembly are respectively connected to the A chamber and the B chamber of the steering cylinder; further, the steering control valve assembly includes a first reversing valve, a second reversing valve and a third reversing valve, the first reversing valve is connected to the P port of the steering control valve assembly, the second reversing valve is connected to the first reversing valve, the third reversing valve is connected to the second reversing valve, and the third reversing valve is connected to the L port and the R port of the steering control valve assembly; at the same time, the system also includes a steering signal valve, the P1 port of the steering signal valve is connected to the signal port of the third reversing valve, and the LS port of the steering signal valve is connected to the LS port of the multi-way valve assembly.

[0020] In this way, when the system receives the first steering signal, the first reversing valve is electrically switched, and the third reversing valve is electrically switched. At this time, the pressure signal of the third reversing valve is transmitted to the multi-way valve assembly through the steering signal valve. The multi-way valve assembly can distribute a certain flow of oil through the P port of the steering control valve assembly. The oil is successively delivered to the steering cylinder through the first reversing valve, the second reversing valve and the third reversing valve to achieve steering. Specifically, the first steering signal can be a steering signal issued by an electronic steering wheel or a steering signal issued by an unmanned driving system. After the hydraulic system receives the steering signal, it can make the first reversing valve electrically switched, and after the third reversing valve is electrically switched, the pressure signal is transmitted to the multi-way valve assembly through the steering signal valve. The multi-way valve assembly distributes a certain flow of oil through the first reversing valve, the second reversing valve and the third reversing valve, thereby achieving electro-hydraulic steering.

[0021] In addition, the system also includes a steering gear, whose P port is connected to the P1 port of the steering control valve assembly, whose LS port is connected to the signal port of the second reversing valve and the P2 port of the steering signal valve, and whose L port and R port are respectively connected to the A cavity and B cavity of the steering cylinder.

[0022] In this way, when the system receives the second steering signal, the pressure signal generated by the LS port of the steering gear is transmitted to the signal port of the second reversing valve and the P2 port of the steering signal valve, the second reversing valve is reversed, and the oil in the oil tank passes through the P port of the steering control valve assembly through the multi-way valve assembly, and is successively delivered to the steering cylinder through the first reversing valve, the second reversing valve and the steering gear to achieve steering. Specifically, the second steering signal can be a steering signal obtained by manually manipulating the mechanical steering wheel when the system is in electro-hydraulic steering. After the hydraulic system receives the steering signal, the second reversing valve can be electrically reversed, thereby further realizing human priority steering through the first reversing valve, the second reversing valve and the steering gear.

[0023] Compared with traditional hydraulic systems that cannot achieve automatic control, the hydraulic system provided by the present application, on the one hand, can achieve automatic electro-hydraulic steering control, and on the other hand, during the automatic electro-hydraulic steering control process, when the mechanical steering wheel is manually manipulated, manual steering can be achieved, and the priority of manual steering is higher than that of automatic electro-hydraulic steering control, thereby greatly improving the safety of vehicle operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0025] Figure 1 A schematic diagram of a steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles provided in an embodiment of the present application;

[0026] Figure 2 for Figure 1 The diagram shown is a connection diagram of a steering control valve assembly in a steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for an industrial vehicle.

[0027] in:

[0028] 1- oil tank, 2- oil suction filter, 3- power assembly, 4- multi-way valve assembly, 41- steering priority valve, 42- overflow valve, 5- steering control valve assembly, 51- first reversing valve, 52- second reversing valve, 53- third reversing valve, 54- safety valve, 6- steering signal valve, 7- steering gear, 8- two-way hydraulic lock, 9- steering cylinder. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0031] Please refer to Figure 1 and Figure 2 , Figure 1 A schematic diagram of a steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles provided in an embodiment of the present application; Figure 2 for Figure 1 The diagram shown is a connection diagram of a steering control valve assembly in a steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for an industrial vehicle.

[0032] The steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles provided in the embodiment of the present application includes an oil tank 1, a multi-way valve assembly 4, a steering control valve assembly 5 and a steering cylinder 9.

[0033] Among them, the P port of the multi-way valve assembly 4 is connected to the oil tank 1, the CF port of the multi-way valve assembly 4 is connected to the P port of the steering control valve assembly 5, and the L port and R port of the steering control valve assembly 5 are respectively connected to the A cavity and B cavity of the steering cylinder 9.

[0034] Further, the steering control valve assembly 5 includes a first reversing valve 51, a second reversing valve 52 and a third reversing valve 53, wherein the first reversing valve 51 is connected to the P port of the steering control valve assembly 5, the oil inlet of the second reversing valve 52 is connected to the oil outlet of the first reversing valve 51, the oil inlet of the third reversing valve 53 is connected to the oil outlet of the second reversing valve 52, and the oil outlet of the third reversing valve 53 is connected to the L port and the R port of the steering control valve assembly 5; meanwhile, the system also includes a steering signal valve 6, wherein the P1 port of the steering signal valve 6 is connected to the signal port of the third reversing valve 53, and the LS port of the steering signal valve 6 is connected to the LS port of the multi-way valve assembly 4. The steering signal valve 6 is specifically a shuttle valve, which includes a first oil inlet P1, a second oil inlet P2 and a working port LS.

[0035] Of course, according to actual needs, the above-mentioned first reversing valve 51 is specifically a two-position three-way electromagnetic reversing valve, the second reversing valve 52 is a two-position three-way hydraulically controlled reversing valve, and the third reversing valve 53 is a three-position five-way electrically-operated proportional reversing valve. The oil inlet of the second reversing valve 52 is connected to the oil outlet of the first reversing valve 51, the oil inlet of the third reversing valve 53 is connected to the oil outlet of the second reversing valve 52, and the oil return port of the third reversing valve 53 is connected to the oil tank 1.

[0036] In this way, when the system receives the first steering signal, the first reversing valve 51 is electrically switched, and the third reversing valve 53 is electrically switched. At this time, the pressure signal of the third reversing valve 53 is transmitted to the multi-way valve assembly 4 through the steering signal valve 6. The multi-way valve assembly 4 can distribute a certain flow of oil through the P port of the steering control valve assembly 5. The oil is successively delivered to the steering cylinder 9 through the first reversing valve 51, the second reversing valve 52 and the third reversing valve 53 to achieve steering. Specifically, the first steering signal can be a steering signal issued by an electronic steering wheel or a steering signal issued by an unmanned driving system. After the hydraulic system receives the steering signal, it can make the first reversing valve 51 electrically switched, and make the third reversing valve 53 transmit the pressure signal to the multi-way valve assembly 4 through the steering signal valve 6 after being energized. The multi-way valve assembly 4 distributes a certain flow of oil through the first reversing valve 51, the second reversing valve 52 and the third reversing valve 53, thereby achieving electro-hydraulic steering.

[0037] In addition, the system also includes a steering gear 7, the P port of the steering gear 7 is connected to the P1 port of the steering control valve assembly 5, the LS port of the steering gear 7 is connected to the signal port of the second reversing valve 52 and the P2 port of the steering signal valve 6, and the L port and R port of the steering gear 7 are respectively connected to the A cavity and B cavity of the steering cylinder 9.

[0038] In this way, when the system receives the second steering signal, the pressure signal generated by the LS port of the steering gear 7 is transmitted to the signal port of the second reversing valve 52 and the P2 port of the steering signal valve 6, the second reversing valve 52 is reversed, and the oil in the oil tank 1 passes through the multi-way valve assembly 4 and the P port of the steering control valve assembly 5, and is successively delivered to the steering cylinder 9 through the first reversing valve 51, the second reversing valve 52 and the steering gear 7 to achieve steering. Specifically, the second steering signal can be a steering signal obtained by manually manipulating the mechanical steering wheel when the system is in electro-hydraulic steering. After the hydraulic system receives the steering signal, the second reversing valve 52 can be electrically reversed, thereby further realizing human priority steering through the first reversing valve 51, the second reversing valve 52 and the steering gear 7.

[0039] Compared with traditional hydraulic systems that cannot achieve automatic control, the hydraulic system provided by the present application, on the one hand, can achieve automatic electro-hydraulic steering control, and on the other hand, during the automatic electro-hydraulic steering control process, when the mechanical steering wheel is manually manipulated, manual steering can be achieved, and the priority of manual steering is higher than that of automatic electro-hydraulic steering control, thereby greatly improving the safety of vehicle operation.

[0040] It should be noted that the multi-way valve assembly 4 integrates a steering priority valve 41. When there is a pressure signal in the system, the steering priority valve 41 supplies oil to the steering system.

[0041] Specifically, the multi-way valve assembly 4 includes a steering priority valve 41, the oil inlet of the steering priority valve 41 is connected to the oil tank 1, and the oil outlet of the steering priority valve 41 is connected to the P port of the steering control valve assembly 5. The steering priority valve 41 is used to supply a preset flow of oil in the oil tank 1 through the P port of the steering control valve assembly 5.

[0042] At the same time, the system also includes a power assembly 3, which is connected to the oil tank 1 and is used to suck oil from the oil tank 1 and supply it to the steering priority valve 41. The power assembly 3 can be a gear pump.

[0043] Of course, according to actual needs, an oil suction filter 2 may be connected between the power assembly 3 and the oil tank 1 to improve the cleanliness of the oil used in the system, which is beneficial to ensure the reliability of the system operation.

[0044] In this way, when the system is started, the gear pump draws oil from the oil tank 1, and the oil passes through the oil suction filter 2, is supplied to the multi-way valve assembly 4, and is supplied to the P port of the steering control valve assembly 5 through the steering priority valve 41 of the multi-way valve assembly 4.

[0045] In addition, the multi-way valve assembly 4 further comprises a relief valve 42 , which is connected to the steering priority valve 41 and the oil tank 1 , and is used to ensure that the working pressure of the steering priority valve 41 does not exceed a first preset value.

[0046] It should be noted that the first preset value can be 9MPa, that is, the relief valve 42 can ensure that the system pressure is maintained at about 9MPa. The relief valve 42 plays a safety protection role in the system. When the system pressure exceeds 9MPa, the relief valve 42 opens to discharge part of the oil in the system into the oil tank 1, so that the system pressure does not exceed 9MPa, thereby ensuring that the system does not cause accidents due to excessive pressure.

[0047] In this embodiment, the system also includes a safety valve 54 / drain valve, which is connected to the LS port of the steering gear 7 and the oil tank 1. The safety valve 54 is used to ensure that the working pressure of the steering gear 7 does not exceed a second preset value. The second preset value can also be adjusted according to the steering needs of the system, and this article does not make any specific restrictions on this.

[0048] In order to achieve the locking of the steering cylinder 9, a bidirectional hydraulic lock 8 is connected between the third reversing valve 53 and the steering cylinder 9. The bidirectional hydraulic lock 8 refers to two hydraulically controlled one-way valves forming a bidirectional hydraulic lock 8. The principle is that the two hydraulically controlled one-way valves take the pressure of the other's oil circuit as the pilot oil. When there is no pressure in one pipeline, the other pipeline is closed at the same time.

[0049] The two-way hydraulic lock 8 can close the two hydraulically controlled one-way valves when the third reversing valve 53 is in the middle position, thereby tightly sealing the oil in the AB chambers of the steering cylinder 9. At this time, the piston of the steering cylinder 9 cannot move due to external force, thereby ensuring the stability and reliability of the system.

[0050] In this embodiment, the T port of the steering gear 7 is connected to the oil tank 1, so that when the vehicle loses power and cannot provide oil to the steering gear 7, the steering gear 7 can be manually operated to suck oil from the T port through the internal one-way valve and then supply it to the steering cylinder 9, thereby realizing manual steering of the vehicle without power. In this way, when the electro-hydraulic steering signal fails or the system has problems, the vehicle can still be guaranteed to have a steering function.

[0051] In summary, the hydraulic system of the present application can provide three steering modes. The first steering mode is manual steering when the vehicle is unpowered, the second steering mode is manual hydraulic steering, and the third steering mode is automatic electro-hydraulic steering.

[0052] The working state of the first steering mode is: when the vehicle loses power, the gear pump does not rotate and cannot provide oil to the steering gear 7. When the steering wheel is manually operated, the steering gear 7 will absorb oil from the T port of the steering gear 7 and supply it to the steering cylinder 9 through the internal one-way valve, thereby realizing manual steering.

[0053] The working state of the second steering mode is: manual hydraulic steering. At this time, the vehicle is running, the gear pump sucks oil from the oil tank 1, and the oil passes through the oil suction filter 2 to supply the steering priority valve 41 of the multi-way valve assembly 4. The CF port of the multi-way valve assembly 4 is connected to the P port of the steering control valve assembly 5. At this time, the electro-hydraulic steering mode is not turned on, and the first reversing valve 51 is not energized (in the right position); when the steering is manually turned, there is a pressure signal at the LS port of the steering gear 7 through the PP port of the steering control valve assembly 5 to one end (P2 port) of the steering signal valve 6. , is transmitted to the LS port of the multi-way valve assembly 4 through the LS port of the steering signal valve 6, so that the steering priority valve 41 can supply a certain flow of oil. The oil passes through the P port of the steering control valve assembly 5 and the first reversing valve 51 (in the right position) to the P1 port of the steering control valve assembly 5, and is supplied to the P port of the steering gear 7, and then supplied to the steering cylinder 9 through the steering gear 7 to realize the steering action; when there is no artificial steering action, there is no pressure signal at the LS port of the steering gear 7, and the steering priority valve 41 will not supply oil to the steering gear 7, and it will directly flow back to the oil tank 1.

[0054] The third steering mode is the automatic electro-hydraulic steering mode: when the electronic steering wheel has a steering signal or the unmanned driving system sends a steering signal, the first reversing valve 51 is electrically switched (switched to the left position), and the third reversing valve 53 is electrically switched (in the left position). At this time, a pressure signal is transmitted from the signal port of the third reversing valve 53 to the steering priority valve 41 of the multi-way valve assembly 4 through the steering signal valve 6. The steering priority valve 41 divides a certain flow of oil through the P port of the steering control valve assembly 5. The oil is successively supplied to the first reversing valve 51 (in the left position), the second reversing valve 52 (in the lower position) and the third reversing valve 53 (in the left position). At this time, the third reversing valve 53 is controlled by the electric signal and is in the left position. The reversing oil is supplied to one end of the steering cylinder 9 through the two-way hydraulic lock 8, thereby realizing the steering function.

[0055] When the system is in the third steering mode, i.e., the automatic electro-hydraulic steering mode, the mechanical steering wheel is manually operated, and the system oil circuit is set to give priority to manual operation. When steering manually, the LS port of the steering gear 7 generates a pressure signal, and acts on the signal port of the second reversing valve 52 and the P2 port of the steering signal valve 6 through the PP port of the steering control valve assembly 5, so that the second reversing valve 52 is switched to the upper position. In this way, even if the first reversing valve 51 is switched, the oil is supplied to the second reversing valve 52 through the first reversing valve 51, and then supplied to the steering gear 7 through the P1 port of the steering control valve assembly 5, thereby realizing manual mechanical hydraulic steering; in addition, even if the third reversing valve 53 is energized, the oil cannot be supplied through the second reversing valve 52, and therefore, the electro-hydraulic steering function does not work at this time, thereby ensuring that manual steering has the highest priority.

[0056] It should be noted that, in this specification, relational terms such as first and second are merely used to distinguish one entity from other entities, but do not necessarily require or imply any actual relationship or order between these entities.

[0057] The above is a detailed introduction to the steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the scheme of the present application and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles, characterized in that: It includes a fuel tank, a multi-way valve assembly, a steering control valve assembly and a steering cylinder; The P port of the multi-way valve assembly is connected to the oil tank, the CF port of the multi-way valve assembly is connected to the P port of the steering control valve assembly, and the L port and the R port of the steering control valve assembly are connected to the A chamber and the B chamber of the steering cylinder respectively; The steering control valve assembly comprises a first reversing valve, a second reversing valve and a third reversing valve, wherein the first reversing valve is connected to the P port of the steering control valve assembly, the second reversing valve is connected to the first reversing valve, the third reversing valve is connected to the second reversing valve, and the third reversing valve is connected to the L port and the R port of the steering control valve assembly; The system further comprises a turn signal valve, wherein a P1 port of the turn signal valve is connected to a signal port of the third reversing valve, and an LS port of the turn signal valve is connected to an LS port of the multi-way valve assembly; When the system receives a first steering signal, the first reversing valve is electrically reversed, and the pressure signal of the third reversing valve is transmitted to the multi-way valve assembly through the steering signal valve, and the multi-way valve assembly distributes oil through the P port of the steering control valve assembly, and the oil is successively delivered to the steering cylinder through the first reversing valve, the second reversing valve and the third reversing valve to achieve steering; The system further comprises a steering gear, wherein the P port of the steering gear is connected to the P1 port of the steering control valve assembly, the LS port of the steering gear is connected to the signal port of the second reversing valve and the P2 port of the steering signal valve, and the L port and the R port of the steering gear are respectively connected to the A cavity and the B cavity of the steering cylinder; When the system receives the second steering signal, the pressure signal generated by the LS port of the steering gear is transmitted to the signal port of the second reversing valve and the P2 port of the steering signal valve to reverse the second reversing valve, and to allow the oil in the oil tank to pass through the multi-way valve assembly and the P port of the steering control valve assembly, and then be delivered to the steering cylinder through the first reversing valve, the second reversing valve and the steering gear in sequence, thereby achieving steering.

2. The steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles according to claim 1, characterized in that: The multi-way valve assembly includes a steering priority valve, the oil inlet of the steering priority valve is connected to the oil tank, and the oil outlet of the steering priority valve is connected to the P port of the steering control valve assembly, so as to supply a preset flow of oil in the oil tank through the P port of the steering control valve assembly.

3. The steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles as claimed in claim 2, characterized in that: The multi-way valve assembly further comprises a relief valve connected to the steering priority valve and the oil tank, and configured to ensure that the working pressure of the steering priority valve does not exceed a first preset value.

4. The steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles as claimed in claim 2, characterized in that: The system further comprises a power assembly connected to the oil tank and used for sucking oil from the oil tank and supplying the oil to the steering priority valve.

5. The steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles as claimed in claim 4, characterized in that: An oil suction filter is connected between the power assembly and the oil tank.

6. The steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles as claimed in claim 1, characterized in that: The system further comprises a safety valve connected to the LS port of the steering gear and the oil tank, and configured to prevent the working pressure of the steering gear from exceeding a second preset value.

7. The steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles as claimed in claim 1, characterized in that: A bidirectional hydraulic lock is connected between the third reversing valve and the steering cylinder.

8. The steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles as claimed in claim 1, characterized in that: The first reversing valve is a two-position three-way electromagnetic reversing valve, the second reversing valve is a two-position three-way hydraulically controlled reversing valve, and the third reversing valve is a three-position five-way electrically-operated proportional reversing valve.

9. The steering priority hydraulic system with mechanical and electro-hydraulic steering controllable for industrial vehicles according to any one of claims 1 to 8, characterized in that: The T port of the steering gear is connected to the oil tank.

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