An electro-hydraulic controlled closed-center automatic steering gear

Abstract

The present invention discloses an electro-hydraulic controlled closed-center automatic steering gear. The inlet of the priority valve is connected to a high-pressure oil source. The CF port of the priority valve is connected to a closed-center steering unit module and a three-position four-way proportional directional reversing valve, respectively. The two working ports of the three-position four-way proportional directional reversing valve are connected to the two-position four-way hydraulically controlled directional reversing valve. The two oil outlets of the two-position four-way hydraulically controlled reversing valve are respectively connected to the two oil ports of the steering cylinder of the mobile machine. The two oil outlets of the closed-center steering unit module are respectively connected to the two oil ports of the steering cylinder of the mobile machine. The outlet of the bypass compensator is connected to the load sensing oil port of the closed-center steering unit module. The load sensing oil port of the bypass compensator is connected to a pressure switch and the hydraulic control port of the two-position four-way hydraulically controlled directional reversing valve. The pressure switch is electrically connected to the three-position four-way proportional directional reversing valve. The present invention provides manual steering mode and automatic steering mode. In the automatic steering mode, the gear can automatically switch to manual steering according to the rotation of the steering wheel, and the automatic steering can be effectively cut off to avoid interference.

Description

Technical Field

[0001] The invention belongs to the technical field of mobile machinery steering, and in particular relates to an electro-hydraulic controlled closed-core automatic steering gear. Background Art

[0002] With the advancement of intelligent non-road mobile machinery in agriculture, construction, mining, and other industries, unmanned and assisted driving are becoming increasingly common. Automatic steering systems based on remote control or other reference guidance reduce driver fatigue, improve driver comfort, and enhance work quality in tractors, combines, corn harvesters, and similar non-road mobile machinery. In precision agriculture, pre-planned work paths ensure that seeds or fertilizers are applied to precise areas in the field at precise quantities. Combines can also optimize their paths based on crop guidance, enabling automatic row alignment. In mining, ore trucks can more efficiently move from pit to stockpile. In construction, graders and rollers can complete their tasks in fewer passes, improving compaction accuracy. Furthermore, for safety reasons and because the control and guidance system cannot perform routine tasks, an operator is often required to have priority control of the vehicle and be able to easily switch between manual and automatic steering. Generally speaking, open-center steering gears are used in steering systems of tractors and other vehicles that use independent steering pumps, while closed-center steering gears are used in steering systems of combine harvesters, construction machinery, etc. that share a steering pump with other working systems.

[0003] Currently, non-road walking machinery uses a traditional hydraulic steering gear to achieve the automatic steering function. In addition to the hydraulic steering gear, a valve group for automatic steering is added, which is connected to the entire steering system through multiple additional pipes. After entering the automatic steering mode, the angle change of the angle sensor installed on the steering column is used to feedback whether the driver is manipulating the steering wheel to decide whether to temporarily turn off the automatic steering function. When the angle sensor does not change, the automatic steering function is turned on again.

[0004] The existing technology adds redundant pipelines, which increases the probability of hydraulic medium leakage. The additional angle sensor also increases the failure rate of the system. The overall structure is not compact enough, which increases the possibility of pipeline connection errors during installation and maintenance. Summary of the Invention

[0005] The purpose of the present invention is to provide an electro-hydraulic controlled closed-core automatic steering gear to solve the above-mentioned problems existing in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] An electro-hydraulic controlled closed-core automatic steering gear comprises a closed-core steering unit module and an electro-hydraulic steering valve module arranged in parallel. The electro-hydraulic steering valve module comprises a priority valve, a pressure switch, a bypass compensator, a three-position four-way proportional directional reversing valve and a two-position four-way hydraulically controlled reversing valve. The inlet of the priority valve is connected to a high-pressure oil source. The CF port of the priority valve is respectively connected to the inlet of the closed-core steering unit module and the oil inlet of the three-position four-way proportional directional reversing valve. The oil return port of the three-position four-way proportional reversing valve is connected to the oil tank of the mobile machinery. The two working ports of the three-position four-way proportional reversing valve are respectively connected to an oil inlet of the two-position four-way hydraulically controlled reversing valve. The two oil outlets of the two-position four-way hydraulically controlled reversing valve are connected to the oil tank of the mobile machinery. They are respectively connected with the two oil ports of the mobile machinery steering cylinder; the left turn oil outlet of the closed-center steering unit module is connected with one oil port of the mobile machine steering cylinder, the right turn oil outlet of the closed-center steering unit module is connected with the other oil port of the mobile machinery steering cylinder, and the oil return port of the closed-center steering unit module is connected to the oil tank of the mobile machinery; the inlet of the bypass compensator is connected with the load sensing oil port of the priority valve, and the outlet of the bypass compensator is connected to the load sensing oil port of the closed-center steering unit module, the load sensing oil port of the bypass compensator is connected to the pressure switch and the hydraulic control port of the two-position four-way hydraulically controlled reversing valve, and the pressure switch is electrically connected to the three-position four-way proportional reversing valve.

[0008] As a preferred technical solution in the present invention, a throttle hole is provided on the pipeline between the load sensing oil port of the priority valve and the inlet of the bypass compensator.

[0009] As a preferred technical solution in the present invention, the load sensing oil port of the priority valve is connected to the oil tank of the mobile machinery through a relief valve, and the relief valve is located between the outlet of the throttle hole and the oil tank of the mobile machinery.

[0010] As a preferred technical solution in the present invention, the electro-hydraulic steering valve module also includes an electro-hydraulic steering valve housing, and the priority valve, pressure switch, bypass compensator, three-position four-way proportional directional valve and two-position four-way hydraulically controlled directional valve are all installed on the electro-hydraulic steering valve housing.

[0011] As a preferred technical solution in the present invention, a first oil port is provided on the housing of the electro-hydraulic steering valve, and the first oil port is connected to the high-pressure oil source and the inlet of the priority valve.

[0012] As a preferred technical solution in the present invention, a second oil port is provided on the closed-center steering unit module and the electro-hydraulic steering valve housing. The second oil port of the closed-center steering unit module is connected to the return oil port of the closed-center steering unit module. The second oil port of the electro-hydraulic steering valve housing is connected to the second oil port of the closed-center steering unit module, the return oil port of the three-position four-way proportional reversing valve and the oil tank of the mobile machinery.

[0013] As a preferred technical solution in the present invention, a third oil port is provided on the closed-center steering unit module and the electro-hydraulic steering valve housing, and the third oil port of the electro-hydraulic steering valve housing is respectively connected to the mobile mechanical steering cylinder and the third oil port of the closed-center steering unit module, and the left turn oil outlet of the closed-center steering unit module is connected to the third oil port of the closed-center steering unit module; a fourth oil port is provided on the closed-center steering unit module and the electro-hydraulic steering valve housing, and the fourth oil port of the closed-center steering unit module is respectively connected to the mobile mechanical steering cylinder and the fourth oil port of the closed-center steering unit module, and the right turn oil outlet of the closed-center steering unit module is connected to the fourth oil port of the closed-center steering unit module.

[0014] As a preferred technical solution in the present invention, a fifth oil port for supplying oil to other components of the mobile machinery is provided on the housing of the electro-hydraulic steering valve. The fifth oil port is connected to the EF port of the priority valve, and the fifth oil port is connected to the oil tank of the mobile machinery through a screw plug.

[0015] As a preferred technical solution in the present invention, a sixth oil port is provided on the housing of the electro-hydraulic steering valve, and the sixth oil port is respectively connected to the pressure switch and the load sensing oil port of the bypass compensator.

[0016] As a preferred technical solution in the present invention, the closed-center steering unit module is provided with a seventh oil port and an eighth oil port, the seventh oil port is respectively connected to the CF port of the priority valve and the inlet of the closed-center steering unit module; the eighth oil port is respectively connected to the outlet of the bypass compensator and the load sensing oil port of the closed-center steering unit module.

[0017] Beneficial effects: The present invention provides a closed-center hydraulic steering gear for use in the hydraulic steering system of non-road mobile machinery, which can provide two functions: manual steering mode and automatic steering mode operated by the steering wheel. In the automatic steering mode, manual steering and automatic steering can be performed, and automatic steering and manual steering can be automatically identified and switched through the pressure signals fed back during manual steering and automatic steering, and the automatic steering can be effectively cut off to avoid interference.

[0018] In manual steering mode, the machine can only steer through the steering wheel. The steering operation of the machine is the same as that of a machine using an ordinary hydraulic steering gear. Automatic steering will not work, and the machine will not steer without turning the steering wheel. Specifically, the high-pressure oil source flows into the closed-center steering unit module through the priority valve. When no steering is performed, the high-pressure oil source is cut off in the closed-center steering unit module. When the closed-center steering unit module turns left or right, the high-pressure oil source flows out from the left-turn oil outlet or right-turn oil outlet of the closed-center steering unit module to the mobile machinery steering cylinder, thereby realizing manual steering.

[0019] In the automatic steering mode, when the driver does not turn the steering wheel under the automatic steering function, the electro-hydraulic controlled closed-center automatic steering device allows the electronic control system of the non-road mobile machinery to convert GPS navigation signals, remote control signals such as operating handles, knobs, electronic steering wheels, etc., and guidance signals such as automatic lane sensors, straight-line walking angle sensors or displacement sensors into current signals and transmit them to the three-position four-way proportional reversing valve. The left and right working states of the three-position four-way proportional reversing valve determine the steering direction, and the size of the input current signal determines the steering speed.

[0020] In automatic steering mode, when the driver turns the steering wheel under manual steering function, the bypass compensator will cut off the pressure signal from the priority valve to the steering unit, and transmit the sensed pressure signal from the closed-core steering unit module to the two-position four-way hydraulically controlled reversing valve. This pressure signal is sufficient to push the two-position four-way hydraulically controlled reversing valve to work in the right position to cut off the automatic steering action; when the steering wheel is not turned, the bypass compensator will connect the pressure signal from the priority valve to the closed-core steering unit module, so that the closed-core steering unit module is in standby state, and the two-position four-way hydraulically controlled reversing valve works in the left position under the action of its own return spring. When the three-position four-way proportional directional reversing valve has a signal input, there will be a corresponding steering action. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 2. It is the oil passage connection diagram of the closed-core automatic steering gear of the present invention;

[0022] Figure 2 It is a structural schematic diagram of the present invention.

[0023] In the figure: 1-closed-center steering unit module; 2-electro-hydraulic steering valve module; 21-priority valve; 22-throttle hole; 23-screw plug; 24-overflow valve; 25-pressure switch; 26-bypass compensator; 27-three-position four-way proportional directional valve; 28-two-position four-way hydraulically controlled directional valve; P-first oil port; T-second oil port; L-third oil port; R-fourth oil port; EF-fifth oil port; Pe-sixth oil port; P1-seventh oil port; Ls-eighth oil port. DETAILED DESCRIPTION

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be briefly introduced below in conjunction with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0025] Example:

[0026] like Figure 1 and Figure 2 As shown, this embodiment provides an electro-hydraulic controlled closed-center automatic steering gear, including a closed-center steering unit module 1 and an electro-hydraulic steering valve module 2 arranged in parallel, wherein the composition of the closed-center steering unit module 1 is basically the same as that of a conventional closed-center steering unit, and the existing closed-center steering unit module can be used, and then connected with the electro-hydraulic steering valve module 2. In actual application, the closed-center steering unit module 1 realizes the manual steering function of steering wheel operation, and the electro-hydraulic steering valve module 2 realizes the automatic steering function under system control.

[0027] The electro-hydraulic steering valve module 2 includes a priority valve 21, a pressure switch 25, a bypass compensator 26, a three-position four-way proportional directional valve 27 and a two-position four-way hydraulically controlled directional valve 28. The hydraulic components are connected to the oil passage inside the closed-center automatic steering gear as shown in the following figure. Figure 1 As shown, the inlet of the priority valve 21 is connected to the high-pressure oil source, the CF port of the priority valve 21 is connected to the inlet of the closed-core steering unit module 1 and the oil inlet of the three-position four-way proportional reversing valve 27 respectively, the left-turn oil outlet of the closed-core steering unit module 1 is connected to an oil port of the mobile machine steering cylinder, the right-turn oil outlet of the closed-core steering unit module 1 is connected to another oil port of the mobile machine steering cylinder, and the oil return port of the closed-core steering unit module 1 is connected to the oil tank of the mobile machine. Through the above structure, the manual steering mode of the closed-core automatic steering gear can be realized.

[0028] In manual steering mode, the machine can only steer through the steering wheel. The steering operation of the machine is the same as that of a machine using an ordinary hydraulic steering gear. Automatic steering will not work, and the machine will not steer without turning the steering wheel. Specifically, the high-pressure oil source flows into the closed-core steering unit module 1 through the priority valve 21. When no steering is performed, the high-pressure oil source is cut off in the closed-core steering unit module 1. When the closed-core steering unit module 1 turns left or right, the high-pressure oil source flows out from the left-turn oil outlet or the right-turn oil outlet of the closed-core steering unit module 1 and flows to the steering cylinder of the mobile machinery to achieve manual steering.

[0029] The oil return port of the three-position four-way proportional directional control valve 27 is connected to the oil tank of the mobile machinery, and the two working ports of the three-position four-way proportional directional control valve 27 are respectively connected to an oil inlet port of the two-position four-way hydraulically controlled directional control valve 28, and the two oil outlets of the two-position four-way hydraulically controlled directional control valve 28 are respectively connected to the two oil ports of the steering cylinder of the mobile machinery, so as to accurately deliver high-pressure oil source to the two-position four-way hydraulically controlled directional control valve 28 according to the left or right turn situation when the mobile machinery automatically turns; the inlet of the bypass compensator 26 is connected to the load sensing oil port of the priority valve 21, and the bypass compensator 26 is connected to the load sensing oil port of the priority valve 21. The outlet of the compensator 26 is connected to the load sensing oil port of the closed-core steering unit module 1, and the load sensing oil port of the bypass compensator 26 is connected to the pressure switch 25 and the hydraulic control port of the two-position four-way hydraulically controlled reversing valve 28. The two-position four-way hydraulically controlled reversing valve 28 can be closed by controlling the oil pressure, and the pressure switch 25 can also receive an oil pressure signal. The pressure switch 25 is electrically connected to the three-position four-way proportional reversing valve 27, which is convenient for controlling the three-position four-way proportional reversing valve 27 to be closed by an electrical signal. Through the above structure, the automatic steering mode of the closed-core automatic steering gear can be realized.

[0030] In automatic steering mode, it is divided into manual steering and automatic steering. When performing steering actions, automatic steering and manual steering will not work at the same time, and manual steering has a higher priority than automatic steering. That is, when the driver turns the steering wheel, the automatic steering will be automatically cut off. When the steering wheel is not sensed to turn, it will immediately switch to automatic steering.

[0031] In the automatic steering mode, when manual steering is performed, the high-pressure oil source flows into the closed-core steering unit module 1 through the priority valve 21, and a part of the high-pressure oil source flows out from the left-turn oil outlet or the right-turn oil outlet of the closed-core steering unit module 1 and flows to the steering cylinder of the mobile machinery to realize manual steering. At the same time, a part of the high-pressure oil source flows from the load sensing oil port of the closed-core steering unit module 1 through the outlet of the bypass compensator 26, and then flows from the load sensing oil port of the bypass compensator 26 to the pressure switch 25 and the hydraulic control port of the two-position four-way hydraulically controlled reversing valve 28, so that the two-position four-way hydraulically controlled reversing valve 28 is closed, and the pressure switch 25 gives an electrical signal to the three-position four-way proportional reversing valve 27 to make it close, thereby ensuring the stability of manual steering.

[0032] In the automatic steering mode, when automatic steering is performed, the high-pressure oil source flows into the three-position four-way proportional reversing valve 27 through the priority valve 21, and then the three-position four-way proportional reversing valve 27 inputs the high-pressure oil source into the two-position four-way hydraulically controlled reversing valve 28 according to the steering situation. The two-position four-way hydraulically controlled reversing valve 28 inputs the high-pressure oil source to the two oil ports of the steering cylinder of the mobile machinery to realize automatic steering.

[0033] Preferably, a sealing ring is provided at the pipe connection between the closed-center steering unit module 1 and the electro-hydraulic steering valve module 2 to enhance the sealing performance.

[0034] It should be noted that the present invention can be simply and conveniently combined with electrical control to realize assisted driving based on GPS navigation or automatic steering. For example, electrical control makes it possible to use closed-core automatic steering devices based on electro-hydraulic control, such as GPS navigation, remote control, and automatic steering. A pressure switch 25 or a pressure sensor can be optionally installed at the sixth oil port Pe of the electro-hydraulic closed-core automatic steering device to collect the pressure control signal of the two-position four-way hydraulically controlled reversing valve. A two-position four-way solenoid reversing valve with the same function can replace the two-position four-way hydraulically controlled reversing valve 28. Another similar solution is to control the two-position four-way solenoid reversing valve according to the electrical signal converted by the pressure switch 25 or the pressure sensor to realize automatic steering and manual priority. Intelligent electronic control can also improve safety by predicting potential stability problems or extremely unsafe conditions that the driver ignores and making safe avoidance strategies.

[0035] The present invention provides a closed-center hydraulic steering gear for use in a hydraulic steering system of non-road mobile machinery, which can provide two functions: a manual steering mode operated by the steering wheel and an automatic steering mode. In the automatic steering mode, manual steering and automatic steering can be performed, and automatic steering and manual steering can be automatically identified and switched through pressure signals fed back during manual steering and automatic steering, and automatic steering can be effectively cut off to avoid interference.

[0036] In manual steering mode, the machine can only steer through the steering wheel. The steering operation of the machine is the same as that of a machine using an ordinary hydraulic steering gear. Automatic steering will not work, and the machine will not steer without turning the steering wheel. Specifically, the high-pressure oil source flows into the closed-core steering unit module 1 through the priority valve 21. When no steering is performed, the high-pressure oil source is cut off in the closed-core steering unit module 1. When the closed-core steering unit module 1 turns left or right, the high-pressure oil source flows out from the left-turn oil outlet or the right-turn oil outlet of the closed-core steering unit module 1 and flows to the steering cylinder of the mobile machinery to achieve manual steering.

[0037] In the automatic steering mode, when the driver does not turn the steering wheel under the automatic steering function, the electro-hydraulic controlled closed-core automatic steering device allows the electronic control system of the non-road mobile machinery to convert GPS navigation signals, remote control signals such as operating handles, knobs, electronic steering wheels, etc., and guidance signals such as automatic lane sensors, straight-line walking angle sensors or displacement sensors into current signals and transmit them to the three-position four-way proportional reversing valve 27. The left and right working states of the three-position four-way proportional reversing valve 27 determine the steering direction, and the size of the input current signal determines the steering speed.

[0038] In the automatic steering mode, when the driver turns the steering wheel under the manual steering function, the bypass compensator 26 will cut off the pressure signal from the priority valve 21 to the steering unit, and transmit the sensed pressure signal of the closed-core steering unit module 1 to the two-position four-way hydraulically controlled reversing valve 28. This pressure signal is sufficient to drive the two-position four-way hydraulically controlled reversing valve 28 to work in the right position to cut off the automatic steering action; when the steering wheel is not turned, the bypass compensator 26 will connect the pressure signal from the priority valve 21 to the closed-core steering unit module 1, so that the closed-core steering unit module 1 is in a standby state, and the two-position four-way hydraulically controlled reversing valve 28 works in the left position under the action of its own return spring. When the three-position four-way proportional directional reversing valve 27 has a signal input, there will be a corresponding steering action.

[0039] As a preferred implementation scheme in this embodiment, it needs to be further explained that a throttle hole 22 is provided on the pipeline between the load sensing oil port of the priority valve 21 and the inlet of the bypass compensator 26, so as to ensure the normal operation of the bypass compensator 26 while giving priority to the supply of high-pressure oil source for driving steering.

[0040] As a preferred embodiment of this embodiment, it should be further explained that the load-sensing oil port of the priority valve 21 is connected to the mobile machine's oil tank via a relief valve 24. The relief valve 24 is located between the outlet of the throttle orifice 22 and the mobile machine's oil tank. The relief valve 24 protects the load-sensing oil port of the priority valve 21 from overload, while the throttle orifice 22 provides a throttling effect, ensuring that the high-pressure oil source is preferentially supplied to the steering drive.

[0041] As a preferred implementation scheme in this embodiment, it should be further explained that the electro-hydraulic steering valve module 2 also includes an electro-hydraulic steering valve housing, and the priority valve 21, pressure switch 25, bypass compensator 26, three-position four-way proportional directional valve 27, and two-position four-way hydraulically controlled directional valve 28 are all mounted on the electro-hydraulic steering valve housing. Bringing all the equipment together can make the use of the electro-hydraulic steering valve module 2 more convenient. Preferably, the electro-hydraulic steering valve housing and the electro-hydraulic steering valve module 2 are connected by bolts, which is simple and stable. All hydraulic valves are threaded cartridge-type, which can facilitate maintenance and replacement. At the same time, the priority valve can be integrated into the working valve group formed by the overall structure, making the electro-hydraulic controlled closed-center automatic steering gear more simple and compact.

[0042] As a preferred implementation scheme in this embodiment, it needs to be further explained that a first oil port P is provided on the housing of the electro-hydraulic steering valve, and the first oil port P is connected to the high-pressure oil source and the inlet of the priority valve 21, thereby making the overall design more complete. When in use, it is only necessary to connect the high-pressure oil source to supply oil to the whole, making subsequent operations simpler.

[0043] As a preferred implementation scheme in this embodiment, it needs to be further explained that a second oil port T is provided on the closed-core steering unit module 1 and the electro-hydraulic steering valve housing. The second oil port T of the closed-core steering unit module 1 is connected to the oil return port of the closed-core steering unit module 1. The second oil port T of the electro-hydraulic steering valve housing is connected to the second oil port T of the closed-core steering unit module 1, the oil return port of the three-position four-way proportional reversing valve 27 and the oil tank of the mobile machinery. In this way, when in use, as long as the second oil port T of the electro-hydraulic steering valve housing is connected to the oil tank, oil return can be conveniently achieved.

[0044] As a preferred implementation scheme in this embodiment, it needs to be further explained that a third oil port L is provided on the closed-core steering unit module 1 and the electro-hydraulic steering valve housing, and the third oil port L of the electro-hydraulic steering valve housing is respectively connected to the mobile mechanical steering cylinder and the third oil port L of the closed-core steering unit module 1, and the left turn oil outlet of the closed-core steering unit module 1 is connected to the third oil port L of the closed-core steering unit module 1; a fourth oil port R is provided on the closed-core steering unit module 1 and the electro-hydraulic steering valve housing, and the fourth oil port R of the closed-core steering unit module 1 is respectively connected to the mobile mechanical steering cylinder and the fourth oil port R of the closed-core steering unit module 1, and the right turn oil outlet of the closed-core steering unit module 1 is connected to the fourth oil port R of the closed-core steering unit module 1, and the whole is connected to the mobile mechanical steering cylinder through the third oil port L and the fourth oil port R of the electro-hydraulic steering valve housing and the mobile mechanical steering cylinder connecting pipe, so as to realize oil supply to the mobile mechanical steering cylinder during steering.

[0045] As a preferred embodiment of this embodiment, it is further noted that the electro-hydraulic steering valve housing is provided with a fifth oil port EF for supplying oil to other components of the mobile machine. This fifth oil port EF is connected to port EF of priority valve 21, which is connected to the mobile machine's oil tank via a screw plug. Priority valve 21 prioritizes oil supply to drive the steering, ensuring steering action and thus providing greater safety. Excess oil flows to the fifth oil port EF to supply other system components.

[0046] As a preferred implementation scheme in this embodiment, it needs to be further explained that a sixth oil port Pe is provided on the housing of the electro-hydraulic steering valve, and the sixth oil port Pe is respectively connected to the load sensing oil ports of the pressure switch 25 and the bypass compensator 26. In simple terms, the pressure switch 25 is installed at the sixth oil port Pe, which facilitates the setting of the pressure switch 25.

[0047] As a preferred implementation scheme in this embodiment, it needs to be further explained that the closed-center steering unit module 1 is provided with a seventh oil port P1 and an eighth oil port Ls. The seventh oil port P1 is respectively connected to the CF port of the priority valve 21 and the inlet of the closed-center steering unit module 1; the eighth oil port Ls is respectively connected to the outlet of the bypass compensator 26 and the load sensing oil port of the closed-center steering unit module 1. The seventh oil port P1 and the eighth oil port Ls facilitate the connection of the oil circuits of the closed-center steering unit module 1 and the electro-hydraulic steering valve module 2.

[0048] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. An electro-hydraulic controlled closed-center automatic steering gear, characterized in that: The invention comprises a closed-core steering unit module (1) and an electro-hydraulic steering valve module (2) arranged in parallel, wherein the electro-hydraulic steering valve module (2) comprises a priority valve (21), a pressure switch (25), a bypass compensator (26), a three-position four-way proportional directional reversing valve (27) and a two-position four-way hydraulically controlled reversing valve (28); the inlet of the priority valve (21) is connected to a high-pressure oil source; the CF port of the priority valve (21) is respectively connected to the inlet of the closed-core steering unit module (1) and the oil inlet of the three-position four-way proportional directional reversing valve (27); the oil return port of the three-position four-way proportional directional reversing valve (27) is connected to the oil tank of the mobile machinery; the two working ports of the three-position four-way proportional directional reversing valve (27) are respectively connected to an oil inlet of the two-position four-way hydraulically controlled reversing valve (28); and the two oil outlets of the two-position four-way hydraulically controlled reversing valve (28) are connected to the oil tank of the mobile machinery. They are respectively connected to the two oil ports of the mobile machine steering cylinder; the left turn oil outlet of the closed-core steering unit module (1) is connected to one oil port of the mobile machine steering cylinder, the right turn oil outlet of the closed-core steering unit module (1) is connected to the other oil port of the mobile machine steering cylinder, and the oil return port of the closed-core steering unit module (1) is connected to the oil tank of the mobile machine; the inlet of the bypass compensator (26) is connected to the load sensing oil port of the priority valve (21), the outlet of the bypass compensator (26) is connected to the load sensing oil port of the closed-core steering unit module (1), the load sensing oil port of the bypass compensator (26) is connected to the pressure switch (25) and the hydraulic control port of the two-position four-way hydraulic control reversing valve (28), and the pressure switch (25) is electrically connected to the three-position four-way proportional reversing valve (27).

2. The electro-hydraulic controlled closed-center automatic steering gear according to claim 1, characterized in that: A throttle hole (22) is provided on the pipeline between the load sensing oil port of the priority valve (21) and the inlet of the bypass compensator (26).

3. The electro-hydraulic controlled closed-center automatic steering gear according to claim 2, characterized in that: The load sensing oil port of the priority valve (21) is connected to the oil tank of the mobile machine through the overflow valve (24), and the overflow valve (24) is located between the outlet of the throttle hole (22) and the oil tank of the mobile machine.

4. The electro-hydraulic controlled closed-center automatic steering gear according to claim 1, characterized in that: The electro-hydraulic steering valve module (2) further comprises an electro-hydraulic steering valve housing, on which a priority valve (21), a pressure switch (25), a bypass compensator (26), a three-position four-way proportional directional valve (27) and a two-position four-way hydraulically controlled directional valve (28) are all mounted.

5. The electro-hydraulic controlled closed-center automatic steering gear according to claim 4, characterized in that: A first oil port (P) is provided on the housing of the electro-hydraulic steering valve, and the first oil port (P) is connected to a high-pressure oil source and an inlet of a priority valve (21).

6. The electro-hydraulic controlled closed-center automatic steering gear according to claim 4, characterized in that: The closed-core steering unit module (1) and the electro-hydraulic steering valve housing are both provided with a second oil port (T); the second oil port (T) of the closed-core steering unit module (1) is connected to the oil return port of the closed-core steering unit module (1); the second oil port (T) of the electro-hydraulic steering valve housing is connected to the second oil port (T) of the closed-core steering unit module (1), the oil return port of the three-position four-way proportional reversing valve (27), and the oil tank of the mobile machine.

7. The electro-hydraulic controlled closed-center automatic steering gear according to claim 4, characterized in that: The closed-core steering unit module (1) and the electro-hydraulic steering valve housing are both provided with a third oil port (L), the third oil port (L) of the electro-hydraulic steering valve housing is respectively connected to the mobile mechanical steering cylinder and the third oil port (L) of the closed-core steering unit module (1), and the left turn oil outlet of the closed-core steering unit module (1) is connected to the third oil port (L) of the closed-core steering unit module (1); the closed-core steering unit module (1) and the electro-hydraulic steering valve housing are both provided with a fourth oil port (R), the fourth oil port (R) of the closed-core steering unit module (1) is respectively connected to the mobile mechanical steering cylinder and the fourth oil port (R) of the closed-core steering unit module (1), and the right turn oil outlet of the closed-core steering unit module (1) is connected to the fourth oil port (R) of the closed-core steering unit module (1).

8. The electro-hydraulic controlled closed-center automatic steering gear according to claim 4, characterized in that: The electro-hydraulic steering valve housing is provided with a fifth oil port (EF) for supplying oil to other components of the mobile machine. The fifth oil port (EF) is connected to the EF port of the priority valve (21). The fifth oil port (EF) is connected to the oil tank of the mobile machine through a screw plug.

9. The electro-hydraulic controlled closed-center automatic steering gear according to claim 4, characterized in that: The electro-hydraulic steering valve housing is provided with a sixth oil port (Pe), which is connected to the pressure switch (25) and the load sensing oil port of the bypass compensator (26).

10. The electro-hydraulic controlled closed-center automatic steering gear according to claim 1, characterized in that: The closed-core steering unit module (1) is provided with a seventh oil port (P1) and an eighth oil port (Ls), the seventh oil port (P1) being connected to the CF port of the priority valve (21) and the inlet of the closed-core steering unit module (1) respectively; the eighth oil port (Ls) being connected to the outlet of the bypass compensator (26) and the load sensing oil port of the closed-core steering unit module (1) respectively.

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