A centering steering system

Abstract

The present application relates to the technical field of engineering machinery, and provides a centering steering system, a front steering axle, a rear steering axle, a switching valve assembly and a steering gear, the front steering axle is connected with a first reversing valve and a second reversing valve for changing the flow direction of hydraulic oil into and out of first and second oil cylinders, the rear steering axle is connected with a third reversing valve and a fourth reversing valve for changing the flow direction of hydraulic oil into and out of third and fourth oil cylinders, the switching valve assembly is connected with a hydraulic pump for providing a hydraulic oil source for centering and locking the front steering axle or / and the rear steering axle at an execution inlet end, the switching valve assembly is electrically connected with an electric controller for switching the hydraulic pump and the front steering axle or / and the rear steering axle on at a control end, and the steering gear provides hydraulic oil for driving the front steering axle or / and the rear steering axle to steer, through the arrangement of the switching valve assembly and the steering gear, the limitation of traditional steering systems on relying on sensors and complex programming is broken through, and low-cost, high-precision and high-reliability steering control is realized.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, and more specifically, to a centering and steering system. Background Technology

[0002] In complex operating environments such as mines and ports, dual-axle wheeled engineering machinery (such as wheeled material handlers) often needs to flexibly switch tire steering modes according to actual working conditions. For example, the front steering axle may turn while the rear steering axle remains locked (suitable for precise control in confined spaces), the rear steering axle may turn while the front steering axle remains locked (enhancing stability under heavy loads), or the front and rear steering axles may coordinate to turn (reducing the turning radius to improve maneuverability). The steering system of such machinery requires frequent mode switching, and the core of this switching lies in centering adjustment—that is, using mechanical or hydraulic means to return the tires of the non-steering axle to a preset center position and lock them, ensuring even tire force distribution during steering, preventing uneven wear, and improving handling stability and equipment lifespan. If centering adjustment fails or lacks precision, it may lead to abnormal tire wear, increased steering resistance, or even mechanical loss of control. Therefore, precise and efficient centering control is a key requirement in system design.

[0003] Currently, mainstream solutions in the industry primarily rely on electronic control systems combining sensors and controllers, using programmed adjustments to the steering cylinder position to achieve centering and locking. However, such systems suffer from complex programming, high sensor costs, and insufficient stability due to response delays, and they also exhibit poor adaptability to harsh operating conditions such as high temperatures and dust. Another solution relies on manual switching of steering modes, but this method is not only time-consuming and cumbersome but also prone to inaccurate centering due to human error, further exacerbating uneven tire wear and shortening the steering system's lifespan. Furthermore, existing dynamic centering functions require high-precision hydraulic valves, significantly increasing system costs. In summary, existing technologies have significant shortcomings in terms of ease of steering mode switching, precision of centering control, system stability, and cost control, making it difficult to meet the high-efficiency and reliable operation requirements of dual-axle wheeled construction machinery in complex environments. Summary of the Invention

[0004] The purpose of this invention is to provide a centering and steering system that solves the problems of cumbersome operation, high cost, and low centering accuracy of existing dual-axle engineering machinery.

[0005] This invention is achieved through the following technical solution: a centering and steering system, comprising:

[0006] The front steering axle includes a first cylinder and a second cylinder for coordinating changes in the steering of the front wheels. The front steering axle is connected to a first directional valve and a second directional valve. The first directional valve and the second directional valve work together to change the flow direction of hydraulic oil into and out of the first cylinder and the second cylinder.

[0007] The rear steering axle includes a third and a fourth hydraulic cylinder for coordinating changes in the steering of the rear wheels. The rear steering axle is connected to a third and a fourth directional valve. The third and fourth directional valves work together to change the flow direction of hydraulic oil into and out of the third and fourth hydraulic cylinders.

[0008] The switching valve assembly has a hydraulic pump connected to its actuation inlet end. The hydraulic pump provides hydraulic oil for centering and locking the front steering axle and / or the rear steering axle. The control end of the switching valve assembly is electrically connected to an electronic controller for switching the hydraulic pump to conduct with the front steering axle and / or the rear steering axle.

[0009] Steering gear, which supplies hydraulic fluid for steering the front and / or rear steering axles.

[0010] Furthermore, the first and third oil cylinders are arranged on the same side. Both the first and third oil cylinders include a first oil port, a second oil port, and a third oil port. When oil is injected through the first oil port, it pushes the piston rods of the first and third oil cylinders to retract. When oil is injected through the second oil port, it pushes the piston rods of the first and third oil cylinders to extend outward. When oil is injected through the first and third oil ports simultaneously, it pushes the piston rods of the first and third oil cylinders to return to center and reset.

[0011] Furthermore, both the second and fourth oil cylinders include a fourth oil port and a fifth oil port. When oil is injected through the fourth oil port, it pushes the piston rods of the second and fourth oil cylinders to extend outward. When oil is injected through the fifth oil port, it pushes the piston rods of the second and fourth oil cylinders to retract.

[0012] Furthermore, both the first and third cylinders include a cylinder body, which is provided with an end cap, a positioning ring, and a base plate in sequence. A first piston is fitted on the piston rod inside the cylinder body. The first piston is limited between the end cap and the positioning ring. A second piston is provided inside the cylinder body, which is limited to sliding between the positioning ring and the base plate. The second piston is provided with a push rod for pushing the piston rod.

[0013] Furthermore, the first directional valve includes a first front valve, a second front valve, and a third front valve. The first front valve can be switched to disconnect or connect the steering gear to the third directional valve. The second front valve can be switched to disconnect or connect the third directional valve to the second oil port of the first cylinder and the fifth oil port of the second cylinder. The third front valve can be switched to disconnect or connect the steering gear to the second directional valve.

[0014] Furthermore, the second directional valve includes a fourth front valve, a fifth front valve, a sixth front valve, a seventh front valve, and an eighth front valve. The fourth front valve can be switched to disconnect or connect the third front valve to the third oil port of the first cylinder. The fifth front valve can be switched to disconnect or connect the third front valve to the fourth oil port of the second cylinder. The sixth front valve can be switched to disconnect or return oil to the third oil port of the first cylinder for unloading. The seventh front valve can be switched to disconnect or return oil to the fourth oil port of the second cylinder for unloading. The eighth front valve can be switched to disconnect or return oil to the second oil port of the first cylinder and the fifth oil port of the second cylinder for unloading.

[0015] Furthermore, the third directional valve includes a first rear valve, a second rear valve, and a third rear valve. The first rear valve can be switched to disconnect or connect the steering gear to the second front valve. The second rear valve can be switched to disconnect or connect the steering gear to the second oil port of the third cylinder and the fifth oil port of the fourth cylinder. The third rear valve can be switched to disconnect or connect the first directional valve and the fourth directional valve.

[0016] Furthermore, the fourth directional valve includes a fourth rear valve, a fifth rear valve, a sixth rear valve, a seventh rear valve, and an eighth rear valve. The fourth rear valve can be switched to disconnect or connect the third rear valve to the third oil port of the third cylinder. The fifth rear valve can be switched to disconnect or connect the third rear valve to the fourth oil port of the fourth cylinder. The sixth rear valve can be switched to disconnect or return oil to the third oil port of the third cylinder for unloading. The seventh rear valve can be switched to disconnect or return oil to the fourth oil port of the fourth cylinder for unloading. The eighth rear valve can be switched to disconnect or return oil to the second oil port of the third cylinder and the fifth oil port of the fourth cylinder for unloading.

[0017] Furthermore, the switching valve assembly includes a first solenoid valve, a second solenoid valve, and a third solenoid valve. The first solenoid valve can be switched to be disconnected, connected to the front steering axle, or connected to the rear steering axle. The second solenoid valve can be switched to be disconnected or connected to both the front and rear steering axles simultaneously for simultaneously driving the front and rear steering axles to center. The third solenoid valve can be switched to be disconnected or connected to both the front and rear steering axles simultaneously for simultaneously locking the front and rear steering axles to center.

[0018] Furthermore, the steering gear includes a sixth port for changing the front steering axle and / or the rear steering axle to right turn and a seventh port for changing the front steering axle and / or the rear steering axle to left turn.

[0019] The present invention has at least the following advantages and beneficial effects: by setting the switching valve assembly and steering gear, multi-mode switching of a single system is realized, breaking through the limitations of traditional steering systems that rely on sensors and complex programming, and realizing low-cost, high-precision, and high-reliability steering control. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a centering and steering system provided by the present invention.

[0021] Figure 2 This is the upper part of the schematic diagram of the centering steering system provided by the present invention, showing the steering of the front steering axle and the centering and locking of the rear steering axle.

[0022] Figure 3 The lower part of the schematic diagram is provided for the centering steering system of the present invention, showing the steering of the front steering axle and the centering and locking of the rear steering axle.

[0023] Figure 4This is the upper part of the schematic diagram of the centering steering system provided by the present invention, showing the steering of the rear steering axle and the centering and locking of the front steering axle.

[0024] Figure 5 The lower part of the schematic diagram is provided for the centering steering system of the present invention, showing the rear steering axle steering and the front steering axle centering and locking.

[0025] Figure 6 The upper part of the schematic diagram of the four-wheel alignment situation in a centering steering system provided by the present invention.

[0026] Figure 7 The lower part of the schematic diagram of a centering steering system for four-wheel centering is provided by the present invention.

[0027] Figure 8 The upper part of the schematic diagram of the four-wheel centering lock situation in a centering steering system provided by the present invention.

[0028] Figure 9 The lower part of the schematic diagram of the four-wheel centering lock situation in a centering steering system provided by the present invention.

[0029] Figure 10 This is a schematic diagram of the upper part of a centering steering system for four-wheel steering, provided by the present invention.

[0030] Figure 11 The lower part of the schematic diagram of a centering steering system for four-wheel steering provided by the present invention.

[0031] Figure 12 This invention provides a schematic diagram of the first directional valve in a centering steering system.

[0032] Figure 13 This invention provides a schematic diagram of a second directional valve in a centering steering system.

[0033] Figure 14 This invention provides a schematic diagram of a third directional valve in a centering steering system.

[0034] Figure 15 This invention provides a schematic diagram of a fourth directional valve in a centering steering system.

[0035] Figure 16 This invention provides a schematic diagram of a commutator in a centering steering system.

[0036] Figure 17 This invention provides a cross-sectional view of the first and third hydraulic cylinders in a centering steering system.

[0037] Reference numerals: 1-Front steering axle, 101-First oil port, 102-Second oil port, 103-Third oil port, 104-Fourth oil port, 105-Fifth oil port, 11-First cylinder, 12-Second cylinder, 2-Rear steering axle, 201-Cylinder body, 202-End cover, 203-Positioning ring, 204-Base plate, 205-First piston, 206-Second piston, 207-Push rod, 21-Third cylinder, 22-Fourth cylinder, 3-Diverter valve assembly, 301-Hydraulic pump, 302-Electrical controller, 31-First solenoid valve, 32-Second solenoid valve 33-Third solenoid valve, 4-Steering gear, 401-Sixth oil port, 402-Seventh oil port, 5-First directional valve, 51-First front valve, 52-Second front valve, 53-Third front valve, 6-Second directional valve, 64-Fourth front valve, 65-Fifth front valve, 66-Sixth front valve, 67-Seventh front valve, 68-Eighth front valve, 7-Third directional valve, 71-First rear valve, 72-Second rear valve, 73-Third rear valve, 8-Fourth directional valve, 84-Fourth rear valve, 85-Fifth rear valve, 86-Sixth rear valve, 87-Seventh rear valve, 88-Eighth rear valve. Detailed Implementation

[0038] The specific implementation method is described below with reference to the accompanying drawings.

[0039] Example

[0040] like Figures 1 to 17 As shown, in this embodiment, a centering steering system is mainly disclosed, the main structure of which includes a front steering axle 1, a rear steering axle 2, a switching valve assembly 3, and a steering gear 4, wherein;

[0041] The front steering axle 1 includes a first cylinder 11 and a second cylinder 12 for coordinating changes in the steering of the front wheels. The front steering axle 1 is connected to a first directional valve 5 and a second directional valve 6. The first directional valve 5 and the second directional valve 6 work together to change the flow direction of hydraulic oil into and out of the first cylinder 11 and the second cylinder 12. The first cylinder 11 and the second cylinder 12 are arranged coaxially opposite each other and coordinate to control the steering of the front wheels. For example, when the piston rod of the first cylinder 11 extends outward, the piston rod of the second cylinder 12 retracts inward synchronously.

[0042] The rear steering axle 2 includes a third cylinder 21 and a fourth cylinder 22 for coordinating changes in the steering of the rear wheels. The rear steering axle 2 is connected to a third directional valve 7 and a fourth directional valve 8. The third directional valve 7 and the fourth directional valve 8 work together to change the flow direction of hydraulic oil into and out of the third cylinder 21 and the fourth cylinder 22. Similarly, the third cylinder 21 and the fourth cylinder 22 are arranged coaxially opposite each other to coordinate the control of the steering of the rear wheels.

[0043] The switching valve assembly 3 has a hydraulic pump 301 connected to its inlet end. The hydraulic pump 301 provides hydraulic oil for centering and locking the front steering axle 1 and / or the rear steering axle 2. The control end of the switching valve assembly 3 is electrically connected to an electronic controller 302 for switching the hydraulic pump 301 to the front steering axle 1 and / or the rear steering axle 2. Specifically, the hydraulic pump 301 can be a gear pump connected to the oil source. The operator selects the desired switching mode via the electronic controller 302 located in the cab, causing the hydraulic pump 301 to connect to the front steering axle 1 and / or the rear steering axle 2 via the switching valve assembly 3 to perform centering and centering locking.

[0044] Steering gear 4 supplies hydraulic fluid to drive the front steering axle 1 and / or the rear steering axle 2. For example... Figure 16 As shown, the steering gear 4 includes a sixth oil port 401 for changing the front steering axle 1 and / or the rear steering axle 2 to right turn and a seventh oil port 402 for changing the front steering axle 1 and / or the rear steering axle 2 to left turn. Specifically, the specific control principle and execution method of the steering gear 4 can adopt existing technology, which is well known to those skilled in the art and is not an improvement of this invention, and will not be described further. The steering gear 4 selectively outputs hydraulic oil supplied by the steering pump provided by the steering gear 4 through the sixth oil port 401 or the seventh oil port 402 according to the left and right rotation of the steering wheel, as the execution oil circuit for driving the front steering axle 1 and / or the rear steering axle 2, which is not aligned and locked, thus realizing left and right steering operations.

[0045] Furthermore, in specific implementation, such as Figures 1 to 11As shown, in the embodiments of the present invention, the first hydraulic cylinder 11 and the third hydraulic cylinder 21 are arranged on the same side. Both the first hydraulic cylinder 11 and the third hydraulic cylinder 21 include a first oil port 101, a second oil port 102, and a third oil port 103. When oil is injected through the first oil port 101, it pushes the piston rods of the first hydraulic cylinder 11 and the third hydraulic cylinder 21 to retract. When oil is injected through the second oil port 102, it pushes the piston rods of the first hydraulic cylinder 11 and the third hydraulic cylinder 21 to extend outwards. When oil is injected through both the first oil port 101 and the third oil port 103 simultaneously, it pushes the piston rods of the first hydraulic cylinder 11 and the third hydraulic cylinder 21 to return to their centered position. The second hydraulic cylinder 12 and the fourth hydraulic cylinder 22 each include a fourth oil port 104 and a fifth oil port 105. When oil is injected through the fourth oil port 104, it pushes the piston rods of the second hydraulic cylinder 12 and the fourth hydraulic cylinder 22 to extend outwards. When oil is injected through the fifth oil port 105, it pushes the piston rods of the second hydraulic cylinder 12 and the fourth hydraulic cylinder 22 to retract. It should be noted that the first cylinder 11 and the second cylinder 12, as well as the third cylinder 21 and the fourth cylinder 22, are controlled in a coordinated manner. For example, when the front steering axle 1 performs a steering operation, hydraulic oil from the steering pump of the steering gear 4 is simultaneously injected through the first oil port 101 of the first oil tank and the fourth oil port 104 of the second oil tank. Both the first cylinder 11 and the second cylinder 12 are actively driven cylinders. However, when the front steering axle 1 performs a centering operation, oil is injected only through the first oil port 101 and the third oil port 103 of the first cylinder 11 simultaneously. The first cylinder 11 is the actively driven cylinder, while the second cylinder 12 is the passively driven cylinder.

[0046] Furthermore, in specific implementation, such as Figure 17As shown, both the first cylinder 11 and the third cylinder 21 provided in this embodiment of the invention include a cylinder body 201. The cylinder body 201 is sequentially provided with an end cap 202, a positioning ring 203, and a base plate 204. A first piston 205 is fitted onto a piston rod inside the cylinder body 201, and the first piston 205 is positioned between the end cap 202 and the positioning ring 203. A second piston 206 is slidably positioned between the positioning ring 203 and the base plate 204 inside the cylinder body 201, and the second piston 206 is provided with a push rod 207 for pushing the piston rod. Specifically, inside the cylinder body 201, the space between the end cap 202 and the first piston 205 forms a first oil chamber communicating with the first oil port 101; the space between the first piston 205 and the second piston 206 forms a second oil chamber communicating with the second oil port 102; and the space between the second piston 206 and the base plate 204 forms a third oil chamber communicating with the third oil port 103. It should be noted that, taking the first cylinder 11 and the third cylinder 21 as examples, when only the first oil port 101 is filled with oil, the first piston 205 is pushed by hydraulic oil towards the base plate 204, and the piston rod retracts to its limit position. When only the second oil port 102 is filled with oil, the first piston 205 is pushed by hydraulic oil towards the end cover 202, and the piston rod extends to its limit position. When the first oil port 101 and the third oil port 103 are filled with oil simultaneously, the side of the second piston 206 near the base plate 204 is pushed by hydraulic oil towards the positioning ring 203, and the side of the first piston 205 near the end cover 202 is pushed by hydraulic oil towards the base plate 204. However, since the side of the second piston 206 near the base plate 204 is smooth, and the first piston 205 is fitted onto the piston rod, the second piston 206 and the end cover 202 are not fully flush. The contact surface of the hydraulic oil is larger than the contact surface between the first piston 205 and the hydraulic oil. According to Pascal's principle, under the same oil pressure, the thrust on the second piston 206 is greater than the thrust on the first piston 205, forming a thrust difference. This causes the push rod 207 of the second piston 206 to push the piston rod towards the end cover 202 until the second piston 206 abuts against the positioning ring 203, achieving precise centering. This places the piston rod in the middle position between the set limit of extension and limit of retraction, corresponding to the tire facing forward.

[0047] Furthermore, in specific implementation, such as Figure 17As shown, the switching valve assembly 3 provided in this embodiment of the invention includes a first solenoid valve 31, a second solenoid valve 32, and a third solenoid valve 33. The first solenoid valve 31 can be switched to open circuit, connected to the front steering axle 1, or connected to the rear steering axle 2. The second solenoid valve 32 can be switched to open circuit or connected to both the front steering axle 1 and the rear steering axle 2 simultaneously for simultaneously driving the front steering axle 1 and the rear steering axle 2 for centering. The third solenoid valve 33 can be switched to open circuit or connected to both the front steering axle 1 and the rear steering axle 2 simultaneously for simultaneously locking the front steering axle 1 and the rear steering axle 2 for centering. Specifically, the first solenoid valve 31 is a three-position four-way valve, with the middle position being the open circuit start position; the second solenoid valve 32 and the third solenoid valve 33 are both two-position four-way valves, with the initial position being open circuit. By changing the energized and de-energized states of the first solenoid valve 31, the second solenoid valve 32, and the third solenoid valve 33 through the electronic controller 302, the switching of different conduction modes, i.e., steering modes, can be achieved.

[0048] Furthermore, in specific implementation, such as Figures 12 to 15 As shown, the first directional valve 5 provided in the embodiment of the present invention includes a first front valve 51, a second front valve 52 and a third front valve 53. The first front valve 51 can be switched to disconnect or connect the steering gear 4 to the third directional valve 7. The second front valve 52 can be switched to disconnect or connect the third directional valve 7 to the second oil port 102 of the first oil cylinder 11 and the fifth oil port 105 of the second oil cylinder 12. The third front valve 53 can be switched to disconnect or connect the steering gear 4 to the second directional valve 6.

[0049] The second directional valve 6 includes a fourth front valve 64, a fifth front valve 65, a sixth front valve 66, a seventh front valve 67, and an eighth front valve 68. The fourth front valve 64 can be switched to disconnect or connect the third front valve 53 to the third oil port 103 of the first cylinder 11. The fifth front valve 65 can be switched to disconnect or connect the third front valve 53 to the fourth oil port 104 of the second cylinder 12. The sixth front valve 66 can be switched to disconnect or return oil to the third oil port 103 of the first cylinder 11 for unloading. The seventh front valve 67 can be switched to disconnect or return oil to the fourth oil port 104 of the second cylinder 12 for unloading. The eighth front valve 68 can be switched to disconnect or return oil to the second oil port 102 of the first cylinder 11 and the fifth oil port 105 of the second cylinder 12 for unloading.

[0050] The third directional valve 7 includes a first rear valve 71, a second rear valve 72, and a third rear valve 73. The first rear valve 71 can be switched to disconnect or connect the steering gear 4 to the second front valve 52. The second rear valve 72 can be switched to disconnect or connect the steering gear 4 to the second oil port 102 of the third cylinder 21 and the fifth oil port 105 of the fourth cylinder 22. The third rear valve 73 can be switched to disconnect or connect the first directional valve 5 and the fourth directional valve 8.

[0051] The fourth directional valve 8 includes a fourth rear valve 84, a fifth rear valve 85, a sixth rear valve 86, a seventh rear valve 87, and an eighth rear valve 88. The fourth rear valve 84 can be switched to disconnect or connect the third rear valve 73 to the third oil port 103 of the third cylinder 21. The fifth rear valve 85 can be switched to disconnect or connect the third rear valve 73 to the fourth oil port 104 of the fourth cylinder 22. The sixth rear valve 86 can be switched to disconnect or return oil to the third oil port 103 of the third cylinder 21 for unloading. The seventh rear valve 87 can be switched to disconnect or return oil to the fourth oil port 104 of the fourth cylinder 22 for unloading. The eighth rear valve 88 can be switched to disconnect or return oil to the second oil port 102 of the third cylinder 21 and the fifth oil port 105 of the fourth cylinder 22 for unloading.

[0052] It should be noted that this invention mainly includes three steering modes:

[0053] (1) First mode (e.g.) Figure 2 , Figure 3 (As shown): Front steering axle 1 steers, rear steering axle 2 is centered and locked.

[0054] When the electronic controller 302 is set to the first mode, the control terminal on one side of the first solenoid valve 31 is energized, and the hydraulic oil of the hydraulic pump 301 is divided into three paths (a, b, and c) and connected to the rear steering axle 2. Specifically, path a serves as the control oil path, entering the third directional valve 7 and flowing to the control inlet ends of the first rear valve 71, the second rear valve 72, and the third rear valve 73, respectively placing the first rear valve 71 in the pass, and the second rear valve 72 and the third rear valve 73 in the open circuit; path b serves as the control oil path, entering the fourth directional valve 8 and connecting to the control inlet ends of the fourth rear valve 84, the fifth rear valve 85, the sixth rear valve 86, the seventh rear valve 87, and the eighth rear valve 88, respectively placing the fourth rear valve 84, the seventh rear valve 87, and the eighth rear valve 88 in the pass, and the fifth rear valve 85 and the sixth rear valve 86 in the open circuit; path c is divided into two execution oil paths, one directly connected to the first oil port 101 of the third cylinder 21, and the other connected to the third oil port 103 of the third cylinder 21 after passing through the fourth rear valve 84. The second oil port 102 of the third oil cylinder 21 and the fifth oil port 105 of the fourth oil cylinder 22 are unloaded by the return flow through the eighth rear valve 88, and the fourth oil port 104 of the fourth oil cylinder 22 is unloaded by the return flow through the seventh rear valve 87. The oil pressure of the first oil port 101 and the third oil port 103 of the third oil cylinder 21 is maintained, and the centering and locking of the rear steering axle 2 is finally achieved.

[0055] Then the front steering axle 1 turns. If the front steering axle 1 turns right, the sixth oil port 401 connects to the third front valve 53 and then splits into two paths. One path directly connects to the first oil port 101 of the first cylinder 11, and the other path connects to the fourth oil port 104 of the second cylinder 12 after passing through the fifth front valve 65. If the front steering axle 1 turns left, the seventh oil port 402 connects to the first rear valve 71 and the second front valve 52 in sequence and then splits into two paths. One path connects to the second oil port 102 of the first cylinder 11, and the other path connects to the fifth oil port 105 of the second cylinder 12.

[0056] (2) Second mode (e.g.) Figure 4 , Figure 5 (As shown): Rear steering axle 2 steers, front steering axle 1 is centered and locked.

[0057] When the electronic controller 302 is set to the second mode, the control terminal on the other side of the first solenoid valve 31 is energized, and the hydraulic oil of the hydraulic pump 301 is divided into three paths (A, B, and C) and connected to the front steering axle 1. Specifically, path A, as a control oil path, enters the first directional valve 5 and flows to the control inlet ends of the first front valve 51, the second front valve 52, and the third front valve 53, respectively placing the first front valve 51 in the pass, and the second front valve 52 and the third front valve 53 in the open circuit; path B, as a control oil path, enters the second directional valve 6 and connects to the control inlet ends of the fourth front valve 64, the fifth front valve 65, the sixth front valve 66, the seventh front valve 67, and the eighth front valve 68, respectively placing the fourth front valve 64, the seventh front valve 67, and the eighth front valve 68 in the pass, and the fifth front valve 65 and the sixth front valve 66 in the open circuit; path C is divided into two execution oil paths, one directly connected to the first oil port 101 of the first cylinder 11, and the other connected to the third oil port 103 of the first cylinder 11 after passing through the fourth front valve 64. The second oil port 102 of the first oil cylinder 11 and the fifth oil port 105 of the second oil cylinder 12 are unloaded by the return flow through the eighth front valve 68, and the fourth oil port 104 of the second oil cylinder 12 is unloaded by the return flow through the seventh front valve 67, so as to maintain the oil pressure of the first oil port 101 and the third oil port 103 of the first oil cylinder 11, and finally realize the centering and locking of the front steering axle 1.

[0058] Then, the rear steering axle 2 turns. If the rear steering axle 2 turns right, the sixth oil port 401 connects to the first front valve 51 and enters the third directional valve 7. After connecting with the third rear valve 73, it splits into two paths. One path directly connects to the first oil port 101 of the third cylinder 21, and the other path connects to the fourth oil port 104 of the fourth cylinder 22 after passing through the fifth rear valve 85. If the rear steering axle 2 turns left, the seventh oil port 402 connects to the second rear valve 72 in sequence and splits into two paths. One path connects to the second oil port 102 of the third cylinder 21, and the other path connects to the fifth oil port 105 of the fourth cylinder 22.

[0059] (3) Third mode: four-wheel steering

[0060] Step 1: Centering the four wheels (e.g.) Figure 6, Figure 7 (As shown)

[0061] First, the control terminal of the second solenoid valve 32 is energized, and the hydraulic oil of the hydraulic pump 301 is simultaneously connected to the front steering axle 1 and the rear steering axle 2. The hydraulic circuit of the steering axle 1 is divided into three circuits: A, B, and C. Specifically, circuit A serves as the control hydraulic circuit, entering the first directional valve 5 and flowing to the control inlet ends of the first front valve 51, the second front valve 52, and the third front valve 53, respectively placing the first front valve 51 in the pass, and the second front valve 52 and the third front valve 53 in the open circuit. Circuit B serves as the control hydraulic circuit, entering the second directional valve 6 and connecting to the control inlet ends of the fourth front valve 64, the fifth front valve 65, the sixth front valve 66, the seventh front valve 67, and the eighth front valve 68, respectively placing the fourth front valve 64, the seventh front valve 67, and the eighth front valve 68 in the pass, and the fifth front valve 65 and the sixth front valve 66 in the open circuit. Circuit C is divided into two execution hydraulic circuits: one is directly connected to the first oil port 101 of the first cylinder 11, and the other is connected to the third oil port 103 of the first cylinder 11 after passing through the fourth front valve 64. The second oil port 102 of the first oil cylinder 11 and the fifth oil port 105 of the second oil cylinder 12 are unloaded by the return flow through the eighth front valve 68, and the fourth oil port 104 of the second oil cylinder 12 is unloaded by the return flow through the seventh front valve 67, so as to maintain the oil pressure of the first oil port 101 and the third oil port 103 of the first oil cylinder 11, and finally realize the centering and locking of the front steering axle 1. After the steering axle 2 is turned on, the oil circuit is divided into three circuits: a, b, and c. Specifically, circuit a serves as the control oil circuit, entering the third directional valve 7 and flowing to the control inlet ends of the first rear valve 71, the second rear valve 72, and the third rear valve 73, respectively placing the first rear valve 71 in the pass, and the second rear valve 72 and the third rear valve 73 in the open circuit. Circuit b serves as the control oil circuit, entering the fourth directional valve 8 and connecting to the control inlet ends of the fourth rear valve 84, the fifth rear valve 85, the sixth rear valve 86, the seventh rear valve 87, and the eighth rear valve 88, respectively placing the fourth rear valve 84, the seventh rear valve 87, and the eighth rear valve 88 in the pass, and the fifth rear valve 85 and the sixth rear valve 86 in the open circuit. Circuit c is divided into two execution oil circuits: one is directly connected to the first oil port 101 of the third cylinder 21, and the other is connected to the third oil port 103 of the third cylinder 21 after passing through the fourth rear valve 84. The second oil port 102 of the third oil cylinder 21 and the fifth oil port 105 of the fourth oil cylinder 22 are unloaded by the return flow through the eighth rear valve 88, and the fourth oil port 104 of the fourth oil cylinder 22 is unloaded by the return flow through the seventh rear valve 87. The oil pressure of the first oil port 101 and the third oil port 103 of the third oil cylinder 21 is maintained, and the centering and locking of the rear steering axle 2 is finally achieved.

[0062] Step 2: Eliminate steering errors of the front steering axle 1 and the rear steering axle 2 (e.g., Figure 8 , Figure 9 (As shown)

[0063] The second solenoid valve 32 is de-energized, and the third solenoid valve 33 is energized, simultaneously connecting the hydraulic oil from the hydraulic pump 301 to both the front steering axle 1 and the rear steering axle 2. The oil circuit connecting the front steering axle 1 is divided into an execution circuit and a control circuit. The execution circuit is directly connected to the second port 102 of the first cylinder 11. The control circuit is divided into two paths: one enters the first directional valve 5, which disconnects the second front valve 52 and the third front valve 53; the other enters the second directional valve 6, which disconnects the fifth front valve 65. The third port 103 of the first cylinder 11 returns oil and is unloaded via the sixth front valve 66. At this time, the first port 101 of the first cylinder 11 and the fourth port 104 and the fifth port 105 of the second cylinder 12 are disconnected, maintaining oil pressure for the alignment lock state. After the steering axle 2 is activated, its hydraulic circuit is divided into an execution hydraulic circuit and a control hydraulic circuit. The execution hydraulic circuit is directly connected to the second port 102 of the third cylinder 21. The control hydraulic circuit is divided into two paths: one path enters the third directional valve 7, which disconnects the second rear valve 72 and the third rear valve 73; the other path enters the fourth directional valve 8, which disconnects the fifth front valve 65. The third port 103 of the third cylinder 21 returns oil and unloads through the sixth rear valve 86. At this time, the first port 101 of the third cylinder 21 and the fourth port 104 and the fifth port 105 of the fourth cylinder 22 are disconnected, but still have oil pressure. This achieves the centering lock state, i.e., four-wheel centering lock.

[0064] Step 3: Four-wheel steering (e.g.) Figure 10 , Figure 11 (As shown)

[0065] The first solenoid valve 31, the second solenoid valve 32, and the third solenoid valve 33 are all de-energized, connecting the cylinders of the front steering axle 1 and the rear steering axle 2 in series. These two steps ensure that the steering angles of the front steering axle 1 and the rear steering axle 2 are the same, guaranteeing steering accuracy and avoiding steering errors. Simultaneously, the cylinder connection sequence of the front steering axle 1 and the rear steering axle 2 ensures that their steering directions are the same, thereby reducing the machine's turning radius. Specifically, if the sixth oil port 401 is open, it splits into two paths after passing through the third front valve 53: one path connects to the first oil port 101 of the first cylinder 11, and the other path connects to the fourth oil port 104 of the second cylinder 12 after passing through the fifth front valve 65. The return oil from the second oil port 102 of the first cylinder 11 and the fifth oil port 105 of the second cylinder 12 flows sequentially through the second front valve 52 and the third rear valve 73, splitting into two paths. One path connects to the first oil port 101 of the third cylinder 21, and the other path connects to the fourth oil port 104 of the fourth cylinder 22 via the fifth rear valve 85, achieving a crab-like right turn with all four wheels moving in the same direction. If the seventh oil port 402 is open, it connects to the second oil port 102 of the third cylinder 21 and the fifth oil port 105 of the fourth cylinder 22 via the second rear valve 72. The return oil from the fourth oil port 104 of the fourth cylinder 22 merges with the return oil from the first oil port 101 of the third cylinder 21 via the fifth rear valve 85, and then sequentially connects to the second oil port 102 of the first cylinder 11 and the fifth oil port 105 of the second cylinder 12 via the third rear valve 73 and the second front valve 52, achieving a crab-like left turn with all four wheels moving in the same direction.

Claims

1. A centering steering system, characterized in that include: The front steering axle (1) includes a first cylinder (11) and a second cylinder (12) for coordinating changes in the steering of the front wheels. The front steering axle (1) is connected to a first directional valve (5) and a second directional valve (6). The first directional valve (5) and the second directional valve (6) work together to change the flow direction of hydraulic oil into and out of the first cylinder (11) and the second cylinder (12). The rear steering axle (2) includes a third cylinder (21) and a fourth cylinder (22) for coordinating changes in the steering of the rear wheels. The rear steering axle (2) is connected to a third directional valve (7) and a fourth directional valve (8). The third directional valve (7) and the fourth directional valve (8) work together to change the flow direction of hydraulic oil into and out of the third cylinder (21) and the fourth cylinder (22). A switching valve assembly (3) is provided with a hydraulic pump (301) connected to its actuation inlet end. The hydraulic pump (301) provides a hydraulic oil source for centering and locking the front steering axle (1) and / or the rear steering axle (2). The control end of the switching valve assembly (3) is electrically connected to an electronic controller (302) for switching the hydraulic pump (301) to conduct with the front steering axle (1) and / or the rear steering axle (2). Steering gear (4), which provides hydraulic fluid for steering the front steering axle (1) and / or the rear steering axle (2); The first oil cylinder (11) and the third oil cylinder (21) are arranged on the same side. The first oil cylinder (11) and the third oil cylinder (21) each include a first oil port (101), a second oil port (102) and a third oil port (103). When oil is injected through the first oil port (101), the piston rods of the first oil cylinder (11) and the third oil cylinder (21) are pushed back. When oil is injected through the second oil port (102), the piston rods of the first oil cylinder (11) and the third oil cylinder (21) are pushed outward. When oil is injected through the first oil port (101) and the third oil port (103) at the same time, the piston rods of the first oil cylinder (11) and the third oil cylinder (21) are pushed back to center.

2. The centering and steering system according to claim 1, characterized in that, Both the second oil cylinder (12) and the fourth oil cylinder (22) include a fourth oil port (104) and a fifth oil port (105). When oil is injected through the fourth oil port (104), the piston rods of the second oil cylinder (12) and the fourth oil cylinder (22) are pushed outward. When oil is injected through the fifth oil port (105), the piston rods of the second oil cylinder (12) and the fourth oil cylinder (22) are pushed back.

3. The centering and steering system according to claim 1, characterized in that, Both the first cylinder (11) and the third cylinder (21) include a cylinder body (201). The cylinder body (201) is provided with an end cap (202), a positioning ring (203) and a base plate (204) in sequence. A first piston (205) is fitted on the piston rod inside the cylinder body (201). The first piston (205) is limited between the end cap (202) and the positioning ring (203). A second piston (206) is limited and slides between the positioning ring (203) and the base plate (204) inside the cylinder body (201). The second piston (206) is provided with a push rod (207) for pushing the piston rod.

4. A centering and steering system according to claim 2, characterized in that, The first directional valve (5) includes a first front valve (51), a second front valve (52) and a third front valve (53). The first front valve (51) can be switched to disconnect or connect the steering gear (4) to the third directional valve (7). The second front valve (52) can be switched to disconnect or connect the third directional valve (7) to the second oil port (102) of the first cylinder (11) and the fifth oil port (105) of the second cylinder (12). The third front valve (53) can be switched to disconnect or connect the steering gear (4) to the second directional valve (6).

5. A centering and steering system according to claim 4, characterized in that, The second directional valve (6) includes a fourth front valve (64), a fifth front valve (65), a sixth front valve (66), a seventh front valve (67), and an eighth front valve (68). The fourth front valve (64) can be switched to disconnect or connect the third front valve (53) to the third oil port (103) of the first cylinder (11). The fifth front valve (65) can be switched to disconnect or connect the third front valve (53) to the fourth oil port (103) of the second cylinder (12). 104), the sixth front valve (66) can be switched to disconnect or the third oil port (103) of the first oil cylinder (11) can return oil to unload, the seventh front valve (67) can be switched to disconnect or the fourth oil port (104) of the second oil cylinder (12) can return oil to unload, and the eighth front valve (68) can be switched to disconnect or the second oil port (102) of the first oil cylinder (11) and the fifth oil port (105) of the second oil cylinder (12) can return oil to unload.

6. A centering and steering system according to claim 5, characterized in that, The third directional valve (7) includes a first rear valve (71), a second rear valve (72) and a third rear valve (73). The first rear valve (71) can be switched to disconnect or connect the steering gear (4) to the second front valve (52). The second rear valve (72) can be switched to disconnect or connect the steering gear (4) to the second oil port (102) of the third cylinder (21) and the fifth oil port (105) of the fourth cylinder (22). The third rear valve (73) can be switched to disconnect or connect the first directional valve (5) and the fourth directional valve (8).

7. A centering and steering system according to claim 6, characterized in that, The fourth reversing valve (8) includes a fourth rear valve (84), a fifth rear valve (85), a sixth rear valve (86), a seventh rear valve (87), and an eighth rear valve (88). The fourth rear valve (84) can be switched to disconnect or connect the third rear valve (73) to the third oil port (103) of the third cylinder (21). The fifth rear valve (85) can be switched to disconnect or connect the third rear valve (73) to the fourth oil port (103) of the fourth cylinder (22). 104), the sixth rear valve (86) can be switched to disconnect or the third oil port (103) of the third oil cylinder (21) can return oil to unload, the seventh rear valve (87) can be switched to disconnect or the fourth oil port (104) of the fourth oil cylinder (22) can return oil to unload, and the eighth rear valve (88) can be switched to disconnect or the second oil port (102) of the third oil cylinder (21) and the fifth oil port (105) of the fourth oil cylinder (22) can return oil to unload.

8. A centering and steering system according to claim 1, characterized in that, The switching valve assembly (3) includes a first solenoid valve (31), a second solenoid valve (32), and a third solenoid valve (33). The first solenoid valve (31) can be switched to open circuit, connected to the front steering axle (1), or connected to the rear steering axle (2). The second solenoid valve (32) can be switched to open circuit or connected to both the front steering axle (1) and the rear steering axle (2) simultaneously to drive the front steering axle (1) and the rear steering axle (2) to center simultaneously. The third solenoid valve (33) can be switched to open circuit or connected to both the front steering axle (1) and the rear steering axle (2) simultaneously to lock the front steering axle (1) and the rear steering axle (2) to center simultaneously.

9. A centering steering system according to claim 1, characterized in that, The steering gear (4) includes a sixth port (401) for changing the front steering axle (1) and / or the rear steering axle (2) to right turn and a seventh port (402) for changing the front steering axle (1) and / or the rear steering axle (2) to left turn.

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