Vehicle steering hydraulic control system and method

Abstract

The invention discloses a vehicle steering hydraulic control system and method. The control system comprises a hydraulic oil tank, an engine, a pump set, a full-hydraulic steering gear, a steering driving mechanism, a rear wheel driving mechanism, a control valve set and an oil way system. According to the control system, the specific path and pressure of hydraulic oil flowing to the front wheel steering driving mechanism and the rear wheel driving mechanism are adjusted through the control valve set and the oil way system, and front wheel steering, rear wheel driving and in-situ steering are achieved. The front wheel steering driving mechanism adopts the design of a steering oil cylinder, a floating oil cylinder and a steering knuckle, and a cylinder rod is locked through a sliding block and a check block. The control valve group adjusts the locking state of the floating oil cylinder and the driving direction of the rear wheel. The oil way system comprises a plurality of oil ways, and effective circulation and control of hydraulic oil are ensured. The system has the advantages of being accurate in adjustment, quick in response, capable of improving steering efficiency, reducing energy consumption, enhancing system stability and reliability, flexibly adapting to various working conditions, simplifying operation and the like.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic control technology, and in particular to a vehicle steering hydraulic control system and method. Background Art

[0002] In the context of the continuous evolution of vehicle technology and the market's demand for ever-increasing vehicle handling performance, the dual-mode steering system has become an important trend in the innovation of modern vehicle steering systems, with its ability to flexibly adjust the steering mode according to changing driving conditions and the specific needs of the driver. In the prior art, a dual-mode steering system and vehicle design disclosed in the Chinese patent document with publication number CN117262003A successfully achieves the free rotation function of the front wheels and the precise steering mechanism based on the kingpin through innovative mechanical structure and connection layout. This system cleverly combines the collaborative operation of the floating cylinder and the steering cylinder, and with the help of precise monitoring of the displacement sensor, ensures the accuracy of the steering operation and the stability of the system.

[0003] Although the CN117262003A patent has made significant achievements in mechanical structure design, it mainly focuses on the innovation of physical structure, and does not elaborate on the control method to achieve efficient operation of this complex mechanical system. Based on the mechanical architecture shown in CN117262003A, a key challenge facing current technology is how to develop a set of control strategies that match it to fully tap the full potential of the dual-mode steering system.

[0004] Traditional hydraulic control systems are generally limited to providing a single power-assist mode, and are difficult to adapt to the high requirements of flexibility and response speed for dual-mode steering systems. During the mode switching process, such systems often experience problems such as response delays, reduced control accuracy, and increased energy consumption, which seriously restricts the further improvement of vehicle handling performance. In addition, existing hydraulic control systems also have obvious deficiencies in accurately controlling steering force, improving steering efficiency, and energy conservation and emission reduction, making it difficult to meet the urgent needs of modern vehicles for high efficiency and environmental protection.

[0005] In view of the above problems, the present invention aims to fill the gap in the prior art on the hydraulic control method of the dual-mode steering system by designing a hydraulic control device and a control method thereof specially customized for the dual-mode steering system. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the above technical defects and provide a vehicle steering hydraulic control system and method, aiming to overcome the limitations of traditional hydraulic control systems in terms of mode switching, precise control and energy consumption management. The core of the present invention is to achieve precise adjustment of steering force and fast and smooth switching of steering modes by optimizing the hydraulic control strategy, thereby comprehensively improving the vehicle's handling performance, driving stability and fuel economy, and laying a solid foundation for the widespread application of dual-mode steering systems.

[0007] In order to solve the above technical problems, the present invention provides a technical solution: a vehicle steering hydraulic control system, comprising:

[0008] A hydraulic oil tank, used for storing and providing hydraulic oil;

[0009] The engine has a plurality of power take-off ports at its output end for providing hydraulic power for front wheel steering and rear wheel drive;

[0010] A pump group, including a steering main pump 1 and a steering main pump 2 connected to one of the power take-off ports of the engine and a rear wheel main pump 1 and a rear wheel main pump 2 connected to another power take-off port of the engine, for converting the power of the engine into hydraulic energy;

[0011] Fully hydraulic steering gear, whose valve core is driven to rotate by the steering wheel to achieve steering control;

[0012] A steering drive mechanism, used to control the steering of the front wheels of the vehicle;

[0013] A rear wheel drive mechanism, comprising a left hydraulic motor for driving a left rear wheel of the vehicle and a right hydraulic motor for driving a right rear wheel of the vehicle;

[0014] Control valve group, used to adjust the path and pressure of hydraulic oil flow to achieve different steering and driving modes;

[0015] The oil circuit system is used to connect the hydraulic oil tank, pump group, full hydraulic steering gear, steering drive mechanism, rear wheel drive mechanism and control valve group to control the circulation and path of the hydraulic oil;

[0016] Among them, the system can adjust the specific path and pressure of the hydraulic oil flow to the front-wheel steering drive mechanism and the rear-wheel drive mechanism through the control valve group and the oil circuit system according to the driver's operation and the preset steering mode, thereby realizing front-wheel steering, rear-wheel drive and on-the-spot steering of the vehicle.

[0017] The above technical solution is preferred, wherein the front wheel steering drive mechanism comprises a steering cylinder, a left floating cylinder, a right floating cylinder, a left front wheel mounting frame and a right front wheel mounting frame, wherein the left front wheel mounting frame and the right front wheel mounting frame both comprise a steering knuckle, wherein the steering knuckle is rotatably arranged on the vehicle frame via a kingpin, wherein the steering cylinder is provided with two output ends which are respectively rotatably connected to the cylinder barrels of the left floating cylinder and the right floating cylinder, and wherein the cylinder rod output ends of the left floating cylinder and the right floating cylinder are respectively rotatably connected to the steering rocker arms on the same sides.

[0018] The above technical solution is preferred, in which a block is provided in the middle of the inner cavity of the left floating cylinder and the right floating cylinder, and the block divides the inner cavity of the cylinder into a rod cavity, a rodless cavity and a middle cavity. Slide blocks are slidably provided in the rod cavity and the rodless cavity, which are used to move closer to each other under the action of hydraulic oil, thereby locking the cylinder rod.

[0019] The above technical solution is preferred, wherein the control valve group includes control valve one, control valve two, control valve three and control valve four; wherein control valve one and control valve two are used to adjust the locking state of the cylinder rods of the left floating cylinder and the right floating cylinder, and control valve three and control valve four are used to control the driving direction of the rear wheel drive mechanism.

[0020] Preferably, the oil circuit system further comprises:

[0021] The first oil circuit is led out from the hydraulic oil tank and connected to the oil filling ports of the steering main pump 1 and the steering main pump 2 to provide hydraulic oil to the steering main pump 1 and the steering main pump 2;

[0022] Oil circuit A is drawn from the oil outlet of the steering main pump 1, connected to the full hydraulic steering gear and steering cylinder in sequence, and finally flows back to the hydraulic oil tank to form the main oil circuit circulation of steering control;

[0023] Oil circuit B is led out from the oil outlet of steering main pump 2 and connected to control valve 1 and control valve 2 respectively, providing power source for the hydraulic oil circuit of steering mode;

[0024] C oil circuit is arranged on the oil outlet end of control valve 1 and is led out from control valve 1. It is provided with a plurality of oil inlet branches connected with the rod chamber and the rodless chamber, and each oil inlet branch is provided with a hydraulically controlled one-way valve for controlling the flow direction of the hydraulic oil and locking the cylinder rod position of the left floating oil cylinder and the right floating oil cylinder;

[0025] Oil circuit D is led out from the middle cavity and connected to the hydraulic oil tank, and is used to return the hydraulic oil squeezed out of the cylinder barrels of the left floating oil cylinder and the right floating oil cylinder to the hydraulic oil tank;

[0026] The control oil circuit is arranged on the oil outlet end of the second control valve, and is led out from the second control valve. A plurality of control oil sub-circuits connected to the hydraulic control end of the hydraulic control check valve are arranged on the control oil circuit, and are used to control the opening and closing of the hydraulic control check valve;

[0027] The second oil circuit is led out from the hydraulic oil tank and connected to the oil filling ports of the rear wheel main pump 1 and the rear wheel main pump 2 to provide hydraulic oil to the rear wheel main pump 1 and the rear wheel main pump 2;

[0028] Oil circuit E is led out from the oil outlet of the rear wheel main pump 1, connected to control valve 3 and the left hydraulic motor respectively, and finally flows back to the hydraulic oil tank to form an oil circuit circulation for the left rear wheel drive;

[0029] The F oil circuit is led out from the oil outlet end of the rear wheel main pump 2, and is respectively connected to the control valve 4 and the right hydraulic motor, and finally flows back to the hydraulic oil tank, forming an oil circuit circulation for the right rear wheel drive.

[0030] Preferably, the above technical solution is that both the first oil circuit and the second oil circuit are provided with oil suction filters.

[0031] The above technical solution is preferred, in which a pressure relief oil circuit is provided between the oil inlet branch circuit and the D oil circuit, and a pressure relief valve is provided on the pressure relief oil circuit.

[0032] On the other hand, the present application also provides a steering control method, comprising the following specific steps:

[0033] Step A: System initialization and default steering mode 1 setting

[0034] After starting the vehicle, the system enters steering mode 1 by default;

[0035] At this time, both control valve 1 and control valve 2 are in the non-powered state, and the hydraulic control check valve maintains its default closed state. In this state, the hydraulic control check valve is a one-way flow, which can prevent the hydraulic oil from flowing back;

[0036] Start the second steering main pump, and inject the hydraulic oil into the rod chamber and rodless chamber of the left floating cylinder and the right floating cylinder respectively through the B oil circuit, C oil circuit and the oil inlet branch;

[0037] In mode 1, the sliders in the left floating cylinder and the right floating cylinder approach each other under the action of hydraulic oil and push the cylinder rod to move to the middle until it is fixed by the block. The hydraulic oil squeezed out of the cylinder barrels of the left floating cylinder and the right floating cylinder flows back to the hydraulic oil tank through the D oil circuit. In mode 1, the hydraulic control one-way valve is in a closed state, so the hydraulic oil in the rod chamber and the rodless chamber will not flow back through the oil inlet branch, thereby ensuring the locking and fixing of the cylinder rod position. In this state, the left floating cylinder and the right floating cylinder are only used as the connecting rod of the front wheel steering drive mechanism, and in this state, the control valve three and the control valve four shall not be energized. The speed of the left hydraulic motor and the right hydraulic motor is controlled by the throttle, and the vehicle speed increases according to the depth of the throttle pedal.

[0038] Step B: Steering mode to control the front wheel steering

[0039] Left steering: The driver operates the steering wheel to turn left, the valve core of the full hydraulic steering gear rotates, and the pressure oil is pushed to the left chamber of the steering cylinder through the A oil circuit, driving the cylinder rod of the steering cylinder to slide to the right, driving the left floating cylinder and the right floating cylinder to slide to the right, and then through the mechanical linkage relationship of the steering rocker arm, the left front wheel mounting frame, the right front wheel mounting frame and the front tire rotate to the left to achieve left steering;

[0040] Right steering: Similarly, the driver operates the steering wheel to turn right, the valve core of the full hydraulic steering gear rotates, and the pressure oil is pushed to the right chamber of the steering cylinder, driving the cylinder rod of the steering cylinder to slide to the left to achieve right steering;

[0041] Step C: Entering Steering Mode 2 and Preparing for Steering on the Spot

[0042] Before the driver selects to enter steering mode 2 by operating the button, the controller needs to detect the vehicle's driving speed and steering wheel angle to determine whether the entry conditions are met; if the conditions are met, the controller controls the motor speeds on both sides of the rear axle according to the driving speed and steering wheel angle to obtain a reasonable turning radius; the specific control logic is to calculate the tire angle according to the steering wheel angle, and then calculate the rear drive wheel speed ratio according to the angle situation to control the speed of the left hydraulic motor and the right hydraulic motor;

[0043] After starting the vehicle, the driver presses the button to select mode 2, first judging whether the left hydraulic motor and the right hydraulic motor are less than the target value, if not, the steering mode 1 is still entered; if satisfied, the steering wheel angle is further judged whether it is less than the target value, if not satisfied, the steering mode 1 is still entered; if satisfied, the control valve 1 and the control valve 2 are energized, and pressure oil is injected into the control port of the hydraulic control check valve through the control oil circuit and the control branch oil circuit, so that it loses the one-way flow function, allowing the hydraulic oil to flow back to the hydraulic oil tank. At this time, the left floating oil cylinder and the right floating oil cylinder can change freely within a certain range to prepare for in-situ steering;

[0044] Step D: Steering mode 2: On-the-spot steering control

[0045] Left on-the-spot steering: The driver operates the steering wheel to turn left, and the control valve 3 is energized, causing the left hydraulic motor to rotate in the opposite direction. The control valve 4 is de-energized, causing the right hydraulic motor to rotate forward. The left rear tire moves backward, and the right rear tire moves forward. Since the front wheels are in a floating state and have a traction angle, the front wheels automatically adjust their direction according to the speed difference of the rear wheels, achieving on-the-spot left steering.

[0046] Right on-the-spot steering: The driver operates the steering wheel to turn right, and the control valve 4 is energized, causing the right hydraulic motor to rotate in the reverse direction and the left hydraulic motor to rotate forward, thus achieving right on-the-spot steering;

[0047] Step E: Mode switching and recovery

[0048] When the driver needs to switch back to steering mode one, he operates the button to cut off the power to control valve one and control valve two, the hydraulically controlled one-way valve resumes its one-way flow function, the cylinder rods of the left floating cylinder and the right floating cylinder are locked and fixed again, and the system returns to steering mode one.

[0049] This application proposes a hydraulic control device and a control method specifically for a dual-mode steering system, which significantly optimizes the performance of the dual-mode steering system. Compared with the prior art, the main advantages of this application are reflected in the following aspects:

[0050] Precise adjustment and rapid response: The hydraulic control device of the present application achieves precise adjustment of steering force and rapid switching of steering modes by optimizing the hydraulic control strategy. This precision ensures that the vehicle can maintain stability and handling performance under different driving conditions and driving requirements, and improves driving safety and comfort.

[0051] Improve steering efficiency and reduce energy consumption: Through the carefully designed oil circuit system and control valve group, this application can more effectively utilize hydraulic energy and reduce energy loss. This not only improves the efficiency of the steering system, but also significantly reduces the energy consumption of the vehicle, which meets the requirements of modern vehicles for energy conservation and emission reduction.

[0052] Enhanced system stability and reliability: The steering control system of this application uses the synergy of the floating cylinder and the steering cylinder, as well as the precise detection of the displacement sensor, to ensure the accuracy and stability of the steering. At the same time, safety measures such as the pressure relief valve and the oil suction filter in the oil system further enhance the reliability and durability of the system.

[0053] Flexible adaptation to various working conditions: The steering control system of the present application can accurately control the path and pressure of the hydraulic oil flowing to the front wheel steering drive mechanism and the rear wheel drive mechanism through the control valve group and the oil circuit system according to the driver's operation and the preset steering mode. This flexibility enables the vehicle to easily cope with different driving environments and operating requirements, such as stability requirements during high-speed driving and rapid steering requirements during harvesting operations.

[0054] Simplify operation and improve user experience: The steering control method of this application is simple and clear. The driver can easily switch the steering mode by operating the button without complicated operation process. This convenience not only improves the driving experience, but also reduces the difficulty of operation and the risk of misoperation.

[0055] In summary, this application significantly improves the performance advantages of the dual-mode steering system by optimizing the hydraulic control strategy, improving the oil circuit system and control valve group design, and providing a flexible steering control method, solves the shortcomings of the existing technology, and provides modern vehicles with a more stable, efficient, energy-saving and flexible steering solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the overall principle of a vehicle steering hydraulic control system of the present application.

[0057] Figure 2 It is a schematic diagram of the internal structure of the left floating cylinder in this application.

[0058] Figure 3 This is a partial schematic diagram of the principle of left steering control in the present application in steering mode one.

[0059] Figure 4 This is a partial schematic diagram of the principle of right steering control in the present application in steering mode one.

[0060] Figure 5 It is a partial schematic diagram of the principle of left on-the-spot steering control in the present application when in steering mode two.

[0061] Figure 6 It is a partial schematic diagram of the principle of right on-the-spot steering control in the present application when in steering mode two.

[0062] Figure 7 This is a block diagram of the switching logic control principle of steering mode one and steering mode two in this application.

[0063] Figure 8 This is a block diagram of the logic control principle of the left hydraulic motor reversal and the right hydraulic motor reversal when the present application is in the steering mode 2.

[0064] Fig. 9 It is a structural schematic diagram of the left front wheel mounting frame in this application.

[0065] As shown in the figure: 1. Hydraulic oil tank, 2. Engine, 3. Control oil circuit, 4. Steering main pump 1, 5. Steering main pump 2, 6. Rear wheel main pump 1, 7. Rear wheel main pump 2, 8. Full hydraulic steering gear, 9. Steering wheel, 10. Left hydraulic motor, 11. Right hydraulic motor, 12. Steering cylinder, 13. Left floating cylinder, 14. Right floating cylinder, 15. Steering knuckle, 16. Kingpin, 17. Steering rocker arm, 18. Block, 19. Rod cavity, 20. Rod cavity, 21, middle cavity, 22, slider, 23, control valve one, 24, control valve two, 25, control valve three, 26, control valve four, 27, first oil circuit, 28, A oil circuit, 29, B oil circuit, 30, C oil circuit, 31, oil inlet branch, 32, hydraulically controlled one-way valve, 33, D oil circuit, 34, control oil circuit, 35, second oil circuit, 36, E oil circuit, 37, F oil circuit, 38, oil suction filter, 39, pressure relief oil circuit, 40, pressure relief valve. DETAILED DESCRIPTION

[0066] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0067] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings, wherein the same components are represented by the same reference numerals.

[0068] It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to directions in the drawings, and the words "inside" and "outside" refer to directions toward or away from the geometric center of a specific component, respectively.

[0069] In order to make the contents of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0070] Refer to the attached Figure 1 -Attached Figure 4 And attached Fig. 9 , a vehicle steering hydraulic control system, the core components of which include: a hydraulic oil tank 1, which serves as a storage and supply source of hydraulic oil; an engine 2, which is specially used to provide power for front wheel steering and rear wheel driving; a pump group, which is composed of a steering main pump 1 4 and a steering main pump 2 5 connected to one of the power take-off ports of the engine 2, and a rear wheel main pump 1 6 and a rear wheel main pump 2 7 connected to another power take-off port of the engine 2, and is responsible for converting the power of the engine 2 into hydraulic energy; a full hydraulic steering gear 8, whose valve core rotates in response to the operation of the steering wheel 9 to realize the input of the steering command; a steering drive mechanism, which is responsible for executing the front wheel steering action; a rear wheel drive mechanism, which includes a left hydraulic motor 10 and a right hydraulic motor 11, which respectively drive the left rear wheel and the right rear wheel of the vehicle; a control valve group, which flexibly adjusts the hydraulic oil flow path and pressure to meet different steering and driving requirements; and an oil circuit system, which serves as a blood vessel connecting various components to ensure the circulation and path control of the hydraulic oil. The steering control system can accurately regulate the path and pressure of the hydraulic oil flowing to the front-wheel steering drive mechanism and the rear-wheel drive mechanism through the control valve group and the oil circuit system according to the driver's instructions and preset steering modes, thereby realizing the complex functions of front-wheel steering, rear-wheel drive and even on-the-spot steering.

[0071] In one embodiment, the front wheel steering drive mechanism is the core part of the entire steering control system. It includes a steering cylinder 12, a left floating cylinder 13, a right floating cylinder 14, a left front wheel mounting frame and a right front wheel mounting frame. The left front wheel mounting frame and the right front wheel mounting frame are both rotatably connected to the vehicle frame through a steering knuckle 15 and a kingpin 16. This design allows the front wheels to flexibly perform steering operations under the drive of the steering wheel 9.

[0072] The steering cylinder 12 has two output ends, which are respectively connected to the cylinder barrels of the left floating cylinder 13 and the right floating cylinder 14. When the steering wheel 9 rotates, the full hydraulic steering gear 8 adjusts the flow direction and pressure of the hydraulic oil according to the rotation angle and direction of the steering wheel 9, thereby driving the cylinder rod of the steering cylinder 12 to extend or retract. The extension or retraction of the cylinder rod of the steering cylinder 12 will further push the cylinder rods of the left floating cylinder 13 and the right floating cylinder 14, and finally drive the left front wheel mounting frame and the right front wheel mounting frame and the front tires thereon to steer through the mechanical linkage relationship of the steering rocker arm 17.

[0073] In addition, the design of the left floating cylinder 13 and the right floating cylinder 14 is also very ingenious. The inner cavity of their cylinder barrels is divided into a rod cavity 19, a rodless cavity 20 and a middle cavity 21 by a block 18. In the rod cavity 19 and the rodless cavity 20, the slider 22 can move closer to each other under the action of hydraulic oil, thereby locking the cylinder rod. This design not only improves the stability of the steering system, but also ensures the accuracy and reliability of the front wheel during the steering process.

[0074] In another embodiment, the control valve group includes a control valve 1 23, a control valve 2 24, a control valve 3 25 and a control valve 4 26. These control valves achieve precise control of the front wheel steering drive mechanism and the rear wheel drive mechanism by accurately adjusting the flow direction and pressure of the hydraulic oil. The control valve 1 23 and the control valve 2 24 are mainly responsible for adjusting the locking state of the cylinder rods of the left floating oil cylinder 13 and the right floating oil cylinder 14. When the cylinder rod needs to be locked, they will adjust the flow direction and pressure of the hydraulic oil so that the sliders 22 are close to each other and lock the cylinder rod. When the cylinder rod needs to be released, they will adjust the flow direction and pressure of the hydraulic oil so that the sliders 22 are separated from each other and release the cylinder rod. The control valve 3 25 and the control valve 4 26 are responsible for controlling the driving direction of the rear wheel drive mechanism. They achieve precise control of the speed and direction of the left hydraulic motor 10 and the right hydraulic motor 11 by adjusting the flow direction and pressure of the hydraulic oil. This control function enables the vehicle to be flexibly adjusted according to the driver's operation and the preset driving mode, thereby meeting the driving requirements under different working conditions.

[0075] Furthermore, the layout and function of the oil circuit system are very cleverly designed. It includes a first oil circuit 27 and a second oil circuit 35 drawn from the hydraulic oil tank 1, which are responsible for providing hydraulic oil to the steering main pump 1 4, the steering main pump 2 5 and the rear wheel main pump 1 6, the rear wheel main pump 2 7 respectively.

[0076] The A oil circuit 28 is led out from the oil outlet of the steering main pump 1 4, connected to the full hydraulic steering gear 8 and the steering cylinder 12 in sequence, and finally flows back to the hydraulic oil tank 1, forming the main oil circuit circulation of the steering control. The B oil circuit 29 is led out from the oil outlet of the steering main pump 2 5, connected to the control valve 1 23 and the control valve 2 24 respectively, providing a power source for the hydraulic oil circuit of the steering mode.

[0077] The C oil circuit 30 is arranged on the oil outlet end of the control valve 1 23 and is led out from the control valve 1 23. It is provided with a plurality of oil inlet branches 31 connected with the rod chamber 19 and the rodless chamber 20. Each oil inlet branch 31 is provided with a hydraulically controlled one-way valve 32, which is used to control the flow direction of the hydraulic oil and lock the cylinder rod position of the left floating cylinder 13 and the right floating cylinder 14. The D oil circuit 33 is led out from the middle chamber 21 and connected to the hydraulic oil tank 1, which is used to return the hydraulic oil squeezed out of the cylinder barrels of the left floating cylinder 13 and the right floating cylinder 14 to the hydraulic oil tank 1.

[0078] In addition, the control oil circuit 34 is arranged on the oil outlet end of the control valve 24, and is led out from the control valve 24, and is provided with a plurality of control oil sub-circuits 3 connected to the hydraulic control end of the hydraulic control check valve 32. These control oil sub-circuits 3 are used to control the opening and closing of the hydraulic control check valve 32, thereby realizing the flexible switching of the cylinder rod locking state.

[0079] In order to improve the safety and reliability of the oil circuit system, an oil suction filter 38 is provided on both the first oil circuit 27 and the second oil circuit 35 to effectively prevent impurities and pollutants from entering the hydraulic system. At the same time, a pressure relief oil circuit 39 is provided between the oil inlet branch circuit 31 and the D oil circuit 33 and is equipped with a pressure relief valve 40. When the system pressure exceeds the set value, the pressure relief valve 40 will automatically open and release the excess hydraulic oil back to the hydraulic oil tank 1, thereby protecting the safety of the system.

[0080] On the other hand, the present application also provides a steering control method, comprising the following specific steps:

[0081] Step A: System initialization and default steering mode 1 setting

[0082] After starting the vehicle, the system enters steering mode 1 by default;

[0083] At this time, both the control valve 1 23 and the control valve 2 24 are in a non-powered state, and the hydraulically controlled one-way valve 32 maintains its default closed state. In this state, the hydraulically controlled one-way valve 32 is a one-way flow, which can prevent the hydraulic oil from flowing back.

[0084] Start the steering main pump 25, and inject the hydraulic oil into the rod chamber 19 and the rodless chamber 20 of the left floating cylinder 13 and the right floating cylinder 14 through the B oil circuit 29, the C oil circuit 30 and the oil inlet branch 31 respectively;

[0085] In mode 1, the sliders 22 in the left floating cylinder 13 and the right floating cylinder 14 approach each other under the action of hydraulic oil and push the cylinder rod to move toward the middle until it is fixed by the block 18. The hydraulic oil squeezed out of the cylinder barrels of the left floating cylinder 13 and the right floating cylinder 14 flows back to the hydraulic oil tank 1 through the D oil circuit 33. In mode 1, the hydraulically controlled one-way valve 32 is in a closed state, so the hydraulic oil in the rod chamber 19 and the rodless chamber 20 will not flow back through the oil inlet branch 31, thereby ensuring that the cylinder rod position is locked and fixed. In this state, the left floating cylinder 13 and the right floating cylinder 14 are only used as connecting rods of the front wheel steering drive mechanism, and in this state, the control valve three 25 and the control valve four 26 shall not be energized. The speed of the left hydraulic motor 10 and the right hydraulic motor 11 is controlled by the accelerator, and the vehicle speed increases according to the depth of the accelerator pedal.

[0086] Step B: Steering mode to control the front wheel steering

[0087] Left steering: The driver operates the steering wheel 9 to rotate to the left, the valve core of the full hydraulic steering gear 8 rotates, and the pressure oil is pushed to the left chamber of the steering cylinder 12 through the A oil circuit 28, driving the cylinder rod of the steering cylinder 12 to slide to the right, driving the left floating cylinder 13 and the right floating cylinder 14 to slide to the right, and then through the mechanical linkage relationship of the steering rocker arm 17, the left front wheel mounting frame, the right front wheel mounting frame and the front tire rotate to the left to achieve left steering;

[0088] Right steering: Similarly, the driver operates the steering wheel 9 to rotate right, the valve core of the full hydraulic steering gear 8 rotates, and the pressure oil is pushed to the right chamber of the steering cylinder 12, driving the cylinder rod of the steering cylinder 12 to slide left, realizing right steering;

[0089] Step C: Entering Steering Mode 2 and Preparing for Steering on the Spot

[0090] Refer to the attached Figure 5 -Attached Figure 8 Before the driver enters the steering mode 2 by operating the button, the controller needs to detect the vehicle speed and steering wheel angle to determine whether the entry conditions are met; if the conditions are met, the controller controls the motor speeds on both sides of the rear axle according to the driving speed and steering wheel angle to obtain a reasonable turning radius; the specific control logic is to calculate the tire angle according to the steering wheel 9 angle, and then calculate the target speed of the rear drive wheel according to the angle, control the speed of the left hydraulic motor 10 and the right hydraulic motor 11, the total steering angle of the steering wheel 9 to the left and right is x, and the real-time steering angle of the steering wheel 9 is x 实时 , left turn is positive, right turn is negative, the speed of left hydraulic motor 10 is β 左 , the speed of the right hydraulic motor 11 is β 右 , the design target vehicle speed is a, then when the steering wheel 9 is controlled to turn, the speeds of the left hydraulic motor 10 and the right hydraulic motor 11 are:

[0091]

[0092]

[0093] After starting the vehicle, the driver selects to enter mode 2 by pressing a button, first judging whether the left hydraulic motor 10 and the right hydraulic motor 11 are less than the target value, if not, the driver still enters steering mode 1; if satisfied, the driver further judges whether the steering wheel angle is less than the target value, if not satisfied, the driver still enters steering mode 1; if satisfied, the control valve 1 23 and the control valve 2 24 are energized, and pressure oil is injected into the control port of the hydraulic control check valve 32 through the control oil circuit 34 and the control branch oil circuit 3, so that the hydraulic oil loses its one-way flow function, allowing the hydraulic oil to flow back to the hydraulic oil tank 1, at this time, the left floating oil cylinder 13 and the right floating oil cylinder 14 can change freely within a certain range, preparing for in-situ steering;

[0094] Step D: Steering mode 2: On-the-spot steering control

[0095] Left on-site steering: The driver operates the steering wheel 9 to rotate left, the control valve 3 25 is energized, so that the left hydraulic motor 10 rotates in the opposite direction, the control valve 4 26 is not energized, and the right hydraulic motor 11 rotates forward; the left rear tire moves backward, and the right rear tire moves forward. Since the front wheels are in a floating state and have a traction angle, the front wheels automatically adjust their direction according to the rear wheel speed difference to achieve on-site left steering;

[0096] Right in-situ steering: The driver operates the steering wheel 9 to rotate right, and the control valve 4 26 is energized, so that the right hydraulic motor 11 rotates in the reverse direction and the left hydraulic motor 10 rotates forward, thus realizing in-situ right steering;

[0097] Step E: Mode switching and recovery

[0098] When the driver needs to switch back to steering mode one, he operates the button to cut off the power to control valve one 23 and control valve two 24, and the hydraulically controlled one-way valve 32 resumes the one-way flow function. The cylinder rods of the left floating cylinder 13 and the right floating cylinder 14 are locked and fixed again, and the system returns to the state of steering mode one.

[0099] When the vehicle is traveling at high speed, the present application uses steering mode one to ensure the stability of the high-speed vehicle and the tires do not deflect during braking; during harvesting operations, steering mode two is used to obtain a smaller turning radius and quickly complete U-turns, thereby increasing the harvesting operation speed.

[0100] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A vehicle steering hydraulic control system, characterized in that: include: A hydraulic oil tank (1), used for storing and providing hydraulic oil; An engine (2) having a plurality of power take-off ports at its output end for providing hydraulic power for front wheel steering and rear wheel driving; A pump group, comprising a steering main pump 1 (4) and a steering main pump 2 (5) connected to one of the power take-off ports of the engine (2) and a rear wheel main pump 1 (6) and a rear wheel main pump 2 (7) connected to the other power take-off port of the engine (2), for converting the power of the engine (2) into hydraulic energy; A fully hydraulic steering gear (8), whose valve core is driven to rotate by a steering wheel (9) to achieve steering control; A steering drive mechanism, used to control the steering of the front wheels of the vehicle; A rear wheel drive mechanism, comprising a left hydraulic motor (10) for driving a left rear wheel of the vehicle and a right hydraulic motor (11) for driving a right rear wheel of the vehicle; Control valve group, used to adjust the path and pressure of hydraulic oil flow to achieve different steering and driving modes; An oil circuit system for connecting a hydraulic oil tank (1), a pump group, a full hydraulic steering gear (8), a steering drive mechanism, a rear wheel drive mechanism and a control valve group to control the circulation and path of the hydraulic oil; Among them, the vehicle steering hydraulic control system can adjust the specific path and pressure of the hydraulic oil flow to the front wheel steering drive mechanism and the rear wheel drive mechanism through the control valve group and the oil circuit system according to the driver's operation and the preset steering mode, thereby realizing front wheel steering, rear wheel drive and on-site steering of the vehicle.

2. A vehicle steering hydraulic control system according to claim 1, characterized in that: The front wheel steering drive mechanism comprises a steering cylinder (12), a left floating cylinder (13), a right floating cylinder (14), a left front wheel mounting frame and a right front wheel mounting frame. The left front wheel mounting frame and the right front wheel mounting frame both comprise a steering knuckle (15). The steering knuckle (15) is rotatably arranged on a vehicle frame via a kingpin (16). The steering cylinder (12) is provided with two output ends which are rotatably connected to the cylinder barrels of the left floating cylinder (13) and the right floating cylinder (14), respectively. The cylinder rod output ends of the left floating cylinder (13) and the right floating cylinder (14) are rotatably connected to the steering rocker arm (17) on the same side.

3. A vehicle steering hydraulic control system according to claim 2, characterized in that: A stopper (18) is provided in the middle of the inner cavity of the left floating cylinder (13) and the right floating cylinder (14). The stopper (18) divides the inner cavity of the cylinder into a rod cavity (19), a rodless cavity (20) and a middle cavity (21). Slide blocks (22) are slidably provided in the rod cavity (19) and the rodless cavity (20) for moving closer to each other under the action of hydraulic oil, thereby locking the cylinder rod.

4. A vehicle steering hydraulic control system according to claim 3, characterized in that: The control valve group includes control valve one (23), control valve two (24), control valve three (25) and control valve four (26); wherein control valve one (23) and control valve two (24) are used to adjust the cylinder rod locking state of the left floating cylinder (13) and the right floating cylinder (14), and control valve three (25) and control valve four (26) are used to control the driving direction of the rear wheel drive mechanism.

5. A vehicle steering hydraulic control system according to claim 4, characterized in that: The oil circuit system further comprises: A first oil circuit (27) is led out from the hydraulic oil tank (1) and connected to the oil filling ports of the steering main pump 1 (4) and the steering main pump 2 (5) to provide hydraulic oil to the steering main pump 1 (4) and the steering main pump 2 (5); An oil circuit (28) is led out from the oil outlet of the steering main pump (4), connected to the full hydraulic steering gear (8), the steering cylinder (12) in sequence, and finally flows back to the hydraulic oil tank (1), forming a main oil circuit circulation for steering control; B oil circuit (29), which is led out from the oil outlet of the steering main pump 2 (5), and is connected to the control valve 1 (23) and the control valve 2 (24), respectively, to provide a power source for the hydraulic oil circuit of the steering mode; C oil circuit (30), which is arranged on the oil outlet end of control valve 1 (23), is led out from control valve 1 (23), and is provided with a plurality of oil inlet branches (31) which are connected with the rod chamber (19) and the rodless chamber (20), and each oil inlet branch (31) is provided with a hydraulically controlled one-way valve (32) for controlling the flow direction of the hydraulic oil and locking the cylinder rod position of the left floating oil cylinder (13) and the right floating oil cylinder (14); The D oil circuit (33) is led out from the middle chamber (21) and connected to the hydraulic oil tank (1), and is used to return the hydraulic oil squeezed out of the cylinder barrels of the left floating oil cylinder (13) and the right floating oil cylinder (14) to the hydraulic oil tank (1); A control oil circuit (34) is arranged on the oil outlet end of the second control valve (24), leads out from the second control valve (24), and is provided with a plurality of control oil sub-circuits (3) connected to the hydraulic control end of the hydraulic control check valve (32), and is used to control the opening and closing of the hydraulic control check valve (32); A second oil circuit (35) is led out from the hydraulic oil tank (1) and connected to the oil filling ports of the rear wheel main pump 1 (6) and the rear wheel main pump 2 (7) to provide hydraulic oil to the rear wheel main pump 1 (6) and the rear wheel main pump 2 (7); The E oil circuit (36) is led out from the oil outlet of the rear wheel main pump 1 (6), connected to the control valve 3 (25) and the left hydraulic motor (10), and finally flows back to the hydraulic oil tank (1), forming an oil circuit circulation for driving the left rear wheel; The F oil circuit (37) is led out from the oil outlet end of the rear wheel main pump 2 (7), connected to the control valve 4 (26) and the right hydraulic motor (11), and finally flows back to the hydraulic oil tank (1), forming an oil circuit circulation for driving the right rear wheel.

6. A vehicle steering hydraulic control system according to claim 5, characterized in that: The first oil circuit (27) and the second oil circuit (35) are both provided with oil suction filters (38).

7. A vehicle steering hydraulic control system according to claim 5, characterized in that: A pressure relief oil circuit (39) is provided between the oil inlet branch circuit (31) and the D oil circuit (33), and a pressure relief valve (40) is provided on the pressure relief oil circuit (39).

8. A steering control method, characterized in that: The specific steps include: Step A: System initialization and default steering mode 1 setting After starting the vehicle, the system enters steering mode 1 by default; At this time, both the control valve 1 (23) and the control valve 2 (24) are in a non-powered state, and the hydraulically controlled one-way valve (32) maintains its default closed state. In this state, the hydraulically controlled one-way valve (32) is a one-way flow, which can prevent the hydraulic oil from flowing back. The second steering main pump (5) is started to inject hydraulic oil into the rod chamber (19) and the rodless chamber (20) of the left floating cylinder (13) and the right floating cylinder (14) respectively through the B oil circuit (29), the C oil circuit (30) and the oil inlet branch circuit (31); In the first mode, the sliders (22) in the left floating cylinder (13) and the right floating cylinder (14) approach each other under the action of the hydraulic oil and push the cylinder rod to move toward the middle until it is fixed by the block (18). The hydraulic oil squeezed out of the cylinder barrels of the left floating cylinder (13) and the right floating cylinder (14) flows back to the hydraulic oil tank (1) through the D oil circuit (33). In the first mode, the hydraulic control one-way valve (32) is in a closed state, so the hydraulic oil in the rod chamber (19) and the rodless chamber (20) will not flow back through the oil inlet branch (31), thereby ensuring that the cylinder rod position is locked and fixed. In this state, the left floating cylinder (13) and the right floating cylinder (14) are only used as the connecting rod of the front wheel steering drive mechanism, and in this state, the control valve three (25) and the control valve four (26) shall not be energized. The rotation speed of the left hydraulic motor (10) and the right hydraulic motor (11) is controlled by the accelerator, and the vehicle speed increases according to the depth of the accelerator pedal. Step B: Steering mode to control the front wheel steering Left steering: the driver operates the steering wheel (9) to rotate to the left, the valve core of the full hydraulic steering gear (8) rotates, and the pressure oil is pushed to the left chamber of the steering cylinder (12) through the A oil circuit (28), driving the cylinder rod of the steering cylinder (12) to slide to the right, driving the left floating cylinder (13) and the right floating cylinder (14) to slide to the right, and then through the mechanical linkage relationship of the steering rocker arm (17), the left front wheel mounting frame, the right front wheel mounting frame and the front tire rotate to the left, realizing left steering; Right steering: Similarly, the driver operates the steering wheel (9) to rotate right, the valve core of the full hydraulic steering gear (8) rotates, and the pressure oil is pushed to the right chamber of the steering cylinder (12), driving the cylinder rod of the steering cylinder (12) to slide leftward, thereby achieving right steering; Step C: Entering Steering Mode 2 and Preparing for Steering on the Spot Before the driver selects to enter the second steering mode by operating the button, the controller needs to detect the vehicle's driving speed and steering wheel angle to determine whether the entry conditions are met; if the conditions are met, the controller controls the rotation speeds of the left hydraulic motor (10) and the right hydraulic motor (11) of the rear axle according to the driving speed and the steering wheel angle to obtain a reasonable turning radius; the specific control logic is to calculate the tire angle according to the steering wheel (9) angle, and then calculate the rear wheel speed ratio according to the angle condition, and control the rotation speeds of the left hydraulic motor (10) and the right hydraulic motor (11); After starting the vehicle, the driver selects to enter mode 2 by pressing a button, firstly judging whether the left hydraulic motor (10) and the right hydraulic motor (11) are less than the target value, if not, then the steering mode 1 is still entered; if satisfied, then further judging whether the steering angle of the steering wheel (9) is less than the target value, if not satisfied, then the steering mode 1 is still entered; if satisfied, then the control valve 1 (23) and the control valve 2 (24) are energized, and pressure oil is injected into the control port of the hydraulic control check valve (32) through the control oil circuit (34) and the control branch oil circuit (3), so that the hydraulic control check valve (32) loses its one-way flow function, allowing the hydraulic oil to flow back to the hydraulic oil tank (1), and at this time, the left floating oil cylinder (13) and the right floating oil cylinder (14) can change freely within a certain range, preparing for on-site steering; Step D: Steering mode 2: On-the-spot steering control Left on-site steering: the driver operates the steering wheel (9) to rotate left, the control valve three (25) is energized, causing the left hydraulic motor (10) to rotate in the reverse direction, the control valve four (26) is de-energized, and the right hydraulic motor (11) rotates forward; the left rear tire moves backward, and the right rear tire moves forward. Since the front wheels are in a floating state and have a traction angle, the front wheels automatically adjust their direction according to the rear wheel speed difference, achieving on-site left steering; Right turn in place: the driver operates the steering wheel (9) to rotate right, the control valve 4 (26) is energized, the right hydraulic motor (11) rotates in the reverse direction, and the left hydraulic motor (10) rotates forward, thus achieving right turn in place; Step E: Mode switching and recovery When the driver needs to switch back to steering mode one, he can operate the button to cut off the power to control valve one (23) and control valve two (24), and the hydraulically controlled one-way valve (32) will resume the one-way flow function. The cylinder rods of the left floating cylinder (13) and the right floating cylinder (14) will be locked and fixed again, and the system will return to the state of steering mode one.

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