Centering steering system

Abstract

The invention relates to the technical field of engineering machinery, and provides a centering steering system which comprises a front steering axle, a rear steering axle, a change-over valve assembly and a steering gear. The front steering axle is connected with a first reversing valve and a second reversing valve which are used for changing the flowing direction of hydraulic oil entering and exiting from a first oil cylinder and a second oil cylinder; the rear steering axle is connected with a third reversing valve and a fourth reversing valve which are used for changing the flowing direction of hydraulic oil entering and exiting the third oil cylinder and the fourth oil cylinder, and the execution inlet end of the conversion valve assembly is connected with a hydraulic pump which provides a hydraulic oil source and is used for centering and locking the front steering axle or / and the rear steering axle. The control end of the change-over valve assembly is electrically connected with an electric controller used for switching connection between the hydraulic pump and the front steering axle or / and the rear steering axle, the steering gear provides hydraulic oil for driving the front steering axle or / and the rear steering axle to steer, and through the arrangement of the change-over valve assembly and the steering gear, the limitation that a traditional steering system depends on a sensor and complex programming is broken through; and low-cost, high-precision and high-reliability steering control is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to a centering steering system. Background Art

[0002] In complex operating scenarios such as mines and ports, dual-axle wheeled engineering machinery (such as wheeled grabbers) often need to flexibly switch tire steering modes according to actual working conditions, for example: the front steering axle turns and the rear steering axle locks (suitable for precise control in narrow spaces), the rear steering axle turns and the front steering axle locks (enhanced heavy-load stability), or the front steering axle and the rear steering axle coordinate steering (reducing the turning radius to improve maneuverability). The steering system of such machinery needs to switch modes frequently, and the core of mode switching lies in centering adjustment - that is, through mechanical or hydraulic means, the tires of the non-steering axle return to the preset center position and lock it to ensure that the tires are evenly stressed during steering, avoid uneven wear, and improve handling stability and equipment life. If the centering adjustment fails or the accuracy is insufficient, it may cause abnormal tire wear, increased steering resistance or even mechanical loss of control. Therefore, accurate and efficient centering control becomes a key requirement for system design.

[0003] At present, the mainstream solutions in the industry mainly rely on electronic control systems that combine sensors and controllers, and adjust the position of the steering cylinder through programming to achieve centering lock. However, such systems have problems such as complex programming, high sensor costs, and insufficient stability due to response delays. They also have poor adaptability to harsh working 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 to operate, but is also prone to inaccurate centering due to human error, further exacerbating tire wear and shortening the life of the steering system. In addition, the existing dynamic centering function requires reliance on high-precision hydraulic valves, which significantly increases the cost of the system. Overall, the existing technology has obvious deficiencies in the convenience of steering mode switching, the accuracy of centering control, the stability of the system, and cost control, making it difficult to meet the needs of efficient and reliable operation of double-axle wheeled engineering machinery in complex environments. Summary of the Invention

[0004] The purpose of the present invention is to provide a centering steering system, which solves the problems of complicated operation, high cost and low centering accuracy of existing double-axle engineering machinery.

[0005] The present invention is achieved through the following technical solutions: A centering steering system, comprising:

[0006] The front steering axle includes a first oil cylinder and a second oil cylinder for cooperatively changing the steering direction of the front wheels. The front steering axle is connected to a first reversing valve and a second reversing valve. The first reversing valve and the second reversing valve cooperate to change the flow direction of hydraulic oil in and out of the first oil cylinder and the second oil cylinder;

[0007] The rear steering axle includes a third oil cylinder and a fourth oil cylinder for cooperatively changing the steering direction of the rear wheels. The rear steering axle is connected to a third reversing valve and a fourth reversing valve. The third reversing valve and the fourth reversing valve cooperate to change the flow direction of hydraulic oil in and out of the third oil cylinder and the fourth oil cylinder;

[0008] A switching valve assembly, wherein the execution inlet end of the switching valve assembly is connected to a hydraulic pump, which provides a hydraulic oil source for centering and locking the front steering axle and / or the rear steering axle, and the control end of the switching valve assembly is electrically connected to an electronic controller for switching the hydraulic pump and the front steering axle and / or the rear steering axle into conduction;

[0009] Steering gear provides hydraulic oil to drive the front steering axle and / or rear steering axle to steer.

[0010] Furthermore, the first oil cylinder and the third oil cylinder are arranged on the same side, and both the first oil cylinder and the third oil cylinder include a first oil port, a second oil port and a third oil port. When the first oil port is filled with oil, the piston rods of the first oil cylinder and the third oil cylinder are pushed to retract. When the second oil port is filled with oil, the piston rods of the first oil cylinder and the third oil cylinder are pushed to extend outward. When the first oil port and the third oil port are filled with oil at the same time, the piston rods of the first oil cylinder and the third oil cylinder are pushed to align and reset.

[0011] Furthermore, the second oil cylinder and the fourth oil cylinder both include a fourth oil port and a fifth oil port. When the fourth oil port is filled with oil, the piston rods of the second oil cylinder and the fourth oil cylinder are pushed outward. When the fifth oil port is filled with oil, the piston rods of the second oil cylinder and the fourth oil cylinder are pushed back.

[0012] Furthermore, the first oil cylinder and the third oil cylinder both include a cylinder body, which is sequentially provided with an end cover, a positioning ring and a bottom plate. A first piston is inherently sleeved on the piston rod in the cylinder body, and the first piston is limited between the end cover and the positioning ring. A second piston is limitedly slid between the positioning ring and the bottom plate in the cylinder body, and the second piston is provided with a push rod for pushing the piston rod.

[0013] Furthermore, the first reversing valve includes a first front valve, a second front valve and a third front valve. The first front valve can be switched to cut off or connect the steering gear to the third reversing valve. The second front valve can be switched to cut off or connect the third reversing 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 cut off or connect the steering gear to the second reversing valve.

[0014] Furthermore, the second reversing 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, and 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 reversing valve includes a first rear valve, a second rear valve and a third rear valve. The first rear valve can be switched to cut off or connect the steering gear to the second front valve. The second rear valve can be switched to cut off 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 cut off or connect the first reversing valve and the fourth reversing valve.

[0016] Furthermore, the fourth reversing 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 open or connect the third rear valve to the third oil port of the third cylinder, the fifth rear valve can be switched to open or connect the third rear valve to the fourth oil port of the fourth cylinder, the sixth rear valve can be switched to open or return oil to the third oil port of the third cylinder for unloading, the seventh rear valve can be switched to open or return oil to the fourth oil port of the fourth cylinder for unloading, and the eighth rear valve can be switched to open 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 conversion valve assembly includes a first solenoid valve, a second solenoid valve and a third solenoid valve. The first solenoid valve can be switched to open circuit, connected with the front steering axle or connected with the rear steering axle. The second solenoid valve can be switched to open circuit or connected with the front steering axle and the rear steering axle at the same time for simultaneously driving the front steering axle and the rear steering axle to align. The third solenoid valve can be switched to open circuit or connected with the front steering axle and the rear steering axle at the same time for simultaneously locking the front steering axle and the rear steering axle to align.

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

[0019] The present invention has at least the following advantages and beneficial effects: by setting up the conversion valve assembly and the 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

[0025] Figure 6 This is the upper part of the principle diagram of the four-wheel centering situation in the centering steering system provided by the present invention.

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

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

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

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

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

[0031] Figure 12 This is a schematic diagram of the first reversing valve in a centering steering system provided by the present invention.

[0032] Figure 13 This is a schematic diagram of the second reversing valve in a centering steering system provided by the present invention.

[0033] Figure 14 This is a schematic diagram of the third reversing valve in a centering steering system provided by the present invention.

[0034] Figure 15 This is a schematic diagram of the fourth reversing valve in a centering steering system provided by the present invention.

[0035] Figure 16 This is a schematic diagram of a commutator in a centering steering system provided by the present invention.

[0036] Figure 17 This is a cross-sectional view of the first oil cylinder and the third oil cylinder in the centering steering system provided by the present invention.

[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 oil cylinder, 12-second oil cylinder, 2-rear steering axle, 201-cylinder body, 202-end cover, 203-locating ring, 204-bottom plate, 205-first piston, 206-second piston, 207-top rod, 21-third oil cylinder, 22-fourth oil cylinder, 3-conversion valve assembly, 301-hydraulic pump, 302-electronic 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 reversing valve, 51-first front valve, 52-second front valve, 53-third front valve, 6-second reversing valve, 64-fourth front valve, 65-fifth front valve, 66-sixth front valve, 67-seventh front valve, 68-eighth front valve, 7-third reversing valve, 71-first rear valve, 72-second rear valve, 73-third rear valve, 8-fourth reversing valve, 84-fourth rear valve, 85-fifth rear valve, 86-sixth rear valve, 87-seventh rear valve, 88-eighth rear valve. DETAILED DESCRIPTION

[0038] The following is a detailed description of the embodiments 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, whose main structure includes a front steering axle 1, a rear steering axle 2, a conversion 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 collaboratively changing the steering of the front wheels. The front steering axle 1 is connected to a first reversing valve 5 and a second reversing valve 6. The first reversing valve 5 and the second reversing valve 6 work together to change the flow direction of the hydraulic oil in and out of the first cylinder 11 and the second cylinder 12; the first cylinder 11 and the second cylinder 12 are coaxially arranged relative to each other to collaboratively 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 synchronously.

[0042] The rear steering axle 2 includes a third cylinder 21 and a fourth cylinder 22 for collaboratively changing the steering of the rear wheels. The rear steering axle 2 is connected to a third reversing valve 7 and a fourth reversing valve 8. The third reversing valve 7 and the fourth reversing valve 8 work together to change the flow direction of the hydraulic oil in and out of the third cylinder 21 and the fourth cylinder 22; similarly, the third cylinder 21 and the fourth cylinder 22 are coaxially arranged relative to each other to collaboratively control the steering of the rear wheels.

[0043] The actuating inlet of the conversion valve assembly 3 is connected to a hydraulic pump 301, which provides hydraulic oil for centering and locking the front steering axle 1 and / or the rear steering axle 2. The control end of the conversion valve assembly 3 is electrically connected to an electronic controller 302, which switches the hydraulic pump 301 between the front steering axle 1 and / or the rear steering axle 2. Specifically, the hydraulic pump 301 can be connected to the oil source using a gear pump. The operator selects the desired mode via the electronic controller 302, located in the cab. This causes the hydraulic pump 301 to conduct oil to the front steering axle 1 and / or the rear steering axle 2 through the conversion valve assembly 3, thereby performing centering and locking.

[0044] The steering gear 4 provides hydraulic oil to drive the front steering axle 1 and / or the rear steering axle 2 to steer. 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 turn right, and a seventh oil port 402 for changing the front steering axle 1 and / or the rear steering axle 2 to turn left. Specifically, the specific control principle and execution method of the steering gear 4 can adopt the existing technology, which is well known to those skilled in the art. It is not an improvement point of the present invention and will not be described in detail. The steering gear 4 can selectively output the hydraulic oil provided by the steering pump provided in 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 an execution oil circuit to drive the front steering axle 1 and / or the rear steering axle 2 that is not locked in the center to steer, thereby realizing left and right steering operations.

[0045] Furthermore, in specific implementation, Figures 1 to 11As shown, the first oil cylinder 11 and the third oil cylinder 21 provided in the embodiment of the present invention 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 the first oil port 101 is filled with oil, the piston rods of the first oil cylinder 11 and the third oil cylinder 21 are pushed back. When the second oil port 102 is filled with oil, the piston rods of the first oil cylinder 11 and the third oil cylinder 21 are pushed outward. When the first oil port 101 and the third oil port 103 are filled with oil at the same time, the piston rods of the first oil cylinder 11 and the third oil cylinder 21 are pushed to align and reset. The second oil cylinder 12 and the fourth oil cylinder 22 each include a fourth oil port 104 and a fifth oil port 105. When the fourth oil port 104 is filled with oil, the piston rods of the second oil cylinder 12 and the fourth cylinder 22 are pushed outward. When the fifth oil port 105 is filled with oil, the piston rods of the second oil cylinder 12 and the fourth cylinder 22 are pushed back. It should be noted that the first and second cylinders 11, as well as the third and fourth cylinders 21, 22, are controlled in a coordinated manner. For example, when the front steering axle 1 is steering, 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. Therefore, the first and second cylinders 11, 12 are both active cylinders. For example, when the front steering axle 1 is centering, oil is injected only through the first and third oil ports 101, 103 of the first cylinder 11. Therefore, the first cylinder 11 is the active cylinder, while the second cylinder 12 is the passive cylinder.

[0046] Furthermore, in specific implementation, Figure 17As shown, the first oil cylinder 11 and the third oil cylinder 21 provided in the embodiment of the present invention each include a cylinder body 201, which is sequentially provided with an end cap 202, a positioning ring 203, and a bottom plate 204. A first piston 205 is inherently sleeved on the piston rod in the cylinder body 201, and the first piston 205 is limited between the end cap 202 and the positioning ring 203. A second piston 206 is limitedly slidable between the positioning ring 203 and the bottom plate 204 in the cylinder body 201. The second piston 206 is provided with a push rod 207 for pushing the piston rod. Specifically, in the cylinder body 201, a first oil chamber connected to the first oil port 101 is formed between the end cap 202 and the first piston 205, a second oil chamber connected to the second oil port 102 is formed between the first piston 205 and the second piston 206, and a third oil chamber connected to the third oil port 103 is formed between the second piston 206 and the bottom plate 204. It should be noted that, taking the first oil cylinder 11 and the third oil cylinder 21 as an example, when only the first oil port 101 is filled with oil, the first piston 205 is pushed by the hydraulic oil to move toward the bottom plate 204, and the piston rod contracts to the limit position. When only the second oil port 102 is filled with oil, the first piston 205 is pushed by the hydraulic oil to move toward the end cover 202, and the piston rod extends to the limit position. When the first oil port 101 and the third oil port 103 are filled with oil at the same time, the second piston 206 is acted upon by the hydraulic oil on the side close to the bottom plate 204, pushing the second piston 206 toward the positioning ring 203, and the first piston 205 is acted upon by the hydraulic oil on the side close to the end cover 202, pushing the first piston 205 (i.e., the piston rod) toward the bottom plate 204. However, since the second piston 206 is smooth when close to the bottom plate 204, and the first piston 205 is sleeved on the piston rod, the second piston 206 and the piston rod are in contact. 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 exerted on the second piston 206 is greater than the thrust of the first piston 205, forming a thrust difference, so that the push rod 207 of the second piston 206 pushes the piston rod to move toward the end cover 202 until the second piston 206 abuts the positioning ring 203, achieving precise alignment, so that the piston rod is in the middle position between the set extreme extension and extreme retraction, corresponding to the tire facing forward.

[0047] Furthermore, in specific implementation, Figure 17As shown, the conversion valve assembly 3 provided in the embodiment of the present 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 to simultaneously drive the front steering axle 1 and the rear steering axle 2 to align. 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 to simultaneously lock the front steering axle 1 and the rear steering axle 2 to align. Specifically, the first solenoid valve 31 is a three-position, four-way valve, with the middle position being the open circuit starting 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. The electronic controller 302 changes the energization and de-energization of the first, second, and third solenoid valves 31, 32, and 33 to achieve switching between different conduction modes, i.e., steering modes.

[0048] Furthermore, in specific implementation, Figures 12 to 15 As shown, the above-mentioned first reversing valve 5 provided in an 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 reversing valve 7, the second front valve 52 can be switched to disconnect or connect the third reversing valve 7 to the second oil port 102 of the first cylinder 11 and the fifth oil port 105 of the second cylinder 12, and the third front valve 53 can be switched to disconnect or connect the steering gear 4 to the second reversing valve 6.

[0049] The second reversing 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 open 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 open 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 open 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 open or return oil to the fourth oil port 104 of the second cylinder 12 for unloading, and the eighth front valve 68 can be switched to open 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 reversing 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 cut off or connect the steering gear 4 to the second front valve 52. The second rear valve 72 can be switched to cut off 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 cut off or connect the first reversing valve 5 and the fourth reversing valve 8.

[0051] 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 open 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 open 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 open 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 open or return oil to the fourth oil port 104 of the fourth cylinder 22 for unloading, and the eighth rear valve 88 can be switched to open 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 the present invention mainly includes three steering modes:

[0053] (1) The first mode (such as Figure 2 、 Figure 3 (as shown): front steering axle 1 steering, rear steering axle 2 centering and locking

[0054] The electronic controller 302 is placed in the first mode, so that the control end 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, line a enters the third reversing valve 7 as a control oil circuit, flows 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 passage and the second rear valve 72 and the third rear valve 73 in open circuit; line b enters the fourth reversing valve 8 as a control oil circuit and is connected 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 passage and the fifth rear valve 85 and the sixth rear valve 86 in open circuit; line c is divided into two execution oil circuits, 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 refluxed and unloaded through the eighth rear valve 88, and the fourth oil port 104 of the fourth oil cylinder 22 is refluxed and unloaded through the seventh rear valve 87, maintaining the oil pressure of the first oil port 101 and the third oil port 103 of the third oil cylinder 21, and finally achieving the centering locking of the rear steering axle 2.

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

[0056] (2) The second mode (such as Figure 4 、 Figure 5 (as shown): rear steering axle 2 steering, front steering axle 1 centering and locking

[0057] The electronic controller 302 is placed in the second mode, so that the control end 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, line A enters the first reversing valve 5 as a control oil circuit, flows to the control inlet ends of the first front valve 51, the second front valve 52 and the third front valve 53, and respectively places the first front valve 51 in passage and the second front valve 52 and the third front valve 53 in open circuit; line B enters the second reversing valve 6 as a control oil circuit and is connected 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, and respectively places the fourth front valve 64, the seventh front valve 67 and the eighth front valve 68 in passage and the fifth front valve 65 and the sixth front valve 66 in open circuit; line C is divided into two execution oil 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 refluxed and unloaded through the eighth front valve 68, and the fourth oil port 104 of the second oil cylinder 12 is refluxed and unloaded through the seventh front valve 67, maintaining the oil pressure of the first oil port 101 and the third oil port 103 of the first oil cylinder 11, and finally achieving the centering 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 is connected to the first front valve 51 and then enters the third reversing valve 7. After being connected to the third rear valve 73, it is divided into two paths. One path is directly connected to the first oil port 101 of the third oil cylinder 21, and the other path is connected to the fourth oil port 104 of the fourth oil cylinder 22 after passing through the fifth rear valve 85; if the rear steering axle 2 turns left, the seventh oil port 402 is sequentially connected to the second rear valve 72 and then divided into two paths. One path is connected to the second oil port 102 of the third oil cylinder 21, and the other path is connected to the fifth oil port 105 of the fourth cylinder 22.

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

[0060] Step 1: Four-wheel alignment (such as Figure 6、 Figure 7 shown)

[0061] First, the control end of the second solenoid valve 32 is energized, and the hydraulic oil of the hydraulic pump 301 is simultaneously conducted to the front steering axle 1 and the rear steering axle 2. The oil circuit that conducts the front steering axle 1 is divided into three circuits, A, B, and C. Specifically, circuit A enters the first reversing valve 5 as a control oil circuit, 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 passage and the second front valve 52 and the third front valve 53 in open circuit; circuit B enters the second reversing valve 6 as a control oil circuit and is connected 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 passage and the fifth front valve 65 and the sixth front valve 66 in open circuit; circuit C is divided into two execution oil circuits, 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 refluxed and unloaded through the eighth front valve 68, and the fourth oil port 104 of the second oil cylinder 12 is refluxed and unloaded through the seventh front valve 67, maintaining the oil pressure of the first oil port 101 and the third oil port 103 of the first oil cylinder 11, and finally achieving the centering locking of the front steering axle 1. After the oil circuit of the steering axle 2 is turned on, it is divided into three paths: a, b and c. Specifically, path a enters the third reversing valve 7 as a control oil circuit, flows to the control inlet ends of the first rear valve 71, the second rear valve 72 and the third rear valve 73, and respectively puts the first rear valve 71 in passage, the second rear valve 72 and the third rear valve 73 in open circuit; path b enters the fourth reversing valve 8 as a control oil circuit and is connected 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, and respectively puts the fourth rear valve 84, the seventh rear valve 87 and the eighth rear valve 88 in passage, and the fifth rear valve 85 and the sixth rear valve 86 in open circuit; path 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 refluxed and unloaded through the eighth rear valve 88, and the fourth oil port 104 of the fourth oil cylinder 22 is refluxed and unloaded through the seventh rear valve 87, maintaining the oil pressure of the first oil port 101 and the third oil port 103 of the third oil cylinder 21, and finally achieving the centering locking of the rear steering axle 2.

[0062] Step 2: Eliminate the steering errors of the front steering axle 1 and the rear steering axle 2 (such as Figure 8 、 Figure 9 shown)

[0063] The second solenoid valve 32 is de-energized, while the third solenoid valve 33 is energized, directing 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 actuating circuit and a control circuit. The actuating circuit directly connects to the second oil port 102 of the first cylinder 11. The control circuit is divided into two paths: one path enters the first reversing valve 5, shutting off the second and third front valves 52 and 53; the other path enters the second reversing valve 6, shutting off the fifth front valve 65. The third oil port 103 of the first cylinder 11 returns oil through the sixth front valve 66, unloading the load. At this point, the first oil port 101 of the first cylinder 11 and the fourth and fifth oil ports 104 and 105 of the second cylinder 12 are shut off, maintaining oil pressure and maintaining the centering lock state. After the steering axle 2 is opened, the oil circuit is divided into an actuating circuit and a control circuit. The actuating circuit is directly connected to the second oil port 102 of the third cylinder 21. The control circuit is divided into two paths: one path enters the third reversing valve 7, shutting off the second rear valve 72 and the third rear valve 73; the other path enters the fourth reversing valve 8, shutting off the fifth front valve 65. The third oil port 103 of the third cylinder 21 returns oil through the sixth rear valve 86 to unload the load. At this time, the first oil port 101 of the third cylinder 21 and the fourth oil ports 104 and fifth oil ports 105 of the fourth cylinder 22 are shut off, maintaining oil pressure. In the centering lock state, the four-wheel centering lock is achieved.

[0064] Step 3: Four-wheel steering (such as Figure 10 、 Figure 11 shown)

[0065] When the first, second, and third solenoid valves 31, 32, and 33 are all de-energized, the oil cylinders of the front steering axle 1 and rear steering axle 2 are connected in series. The above two steps ensure that the steering angles of the front and rear steering axles 1 and 2 are the same, ensuring steering accuracy and avoiding steering errors. Furthermore, the connection sequence of the oil cylinders of the front and rear steering axles 1 and 2 ensures that the steering directions of the front and rear steering axles 1 and 2 are the same, thereby reducing the turning radius of the machine. Specifically, if the sixth oil port 401 is open, it will be divided into two paths after passing through the third front valve 53: one path connects to the first oil port 101 of the first oil cylinder 11, and the other path connects to the fourth oil port 104 of the second oil cylinder 12 after passing through the fifth front valve 65. The return oil from the second port 102 of the first cylinder 11 and the fifth port 105 of the second cylinder 12 flows through the second front valve 52 and the third rear valve 73, splitting into two paths. One path connects to the first port 101 of the third cylinder 21, and the other connects to the fourth port 104 of the fourth cylinder 22 after passing through the fifth rear valve 85, enabling a four-wheel crab-like right turn. If the seventh port 402 is open, it passes through the second rear valve 72 to connect to the second port 102 of the third cylinder 21 and the fifth port 105 of the fourth cylinder 22, respectively. The return oil from the fourth port 104 of the fourth cylinder 22 passes through the fifth rear valve 85, merges with the return oil from the first port 101 of the third cylinder 21, and then passes through the third rear valve 73 and the second front valve 52, respectively, to connect to the second port 102 of the first cylinder 11 and the fifth port 105 of the second cylinder 12, enabling a four-wheel crab-like left turn.

Claims

1. A centering steering system, characterized in that: include: A front steering axle (1), the front steering axle (1) comprising a first oil cylinder (11) and a second oil cylinder (12) for cooperatively changing the steering direction of the front wheels, the front steering axle (1) being connected to a first reversing valve (5) and a second reversing valve (6), the first reversing valve (5) and the second reversing valve (6) cooperating to change the flow direction of hydraulic oil into and out of the first oil cylinder (11) and the second oil cylinder (12); A rear steering axle (2), the rear steering axle (2) comprising a third oil cylinder (21) and a fourth oil cylinder (22) for cooperatively changing the steering direction of the rear wheels, the rear steering axle (2) being connected to a third reversing valve (7) and a fourth reversing valve (8), the third reversing valve (7) and the fourth reversing valve (8) cooperating to change the flow direction of hydraulic oil into and out of the third oil cylinder (21) and the fourth oil cylinder (22); A conversion valve assembly (3), wherein an execution inlet end of the conversion valve assembly (3) is connected to a hydraulic pump (301), 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), and a control end of the conversion valve assembly (3) is electrically connected to an electronic controller (302) for switching the hydraulic pump (301) to conduction with the front steering axle (1) and / or the rear steering axle (2); A steering gear (4) provides hydraulic oil for driving the front steering axle (1) and / or the rear steering axle (2) to steer.

2. A centering steering system according to claim 1, characterized in that: 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) both include a first oil port (101), a second oil port (102) and a third oil port (103). When the first oil port (101) is filled with oil, the piston rods of the first oil cylinder (11) and the third oil cylinder (21) are pushed to retract. When the second oil port (102) is filled with oil, the piston rods of the first oil cylinder (11) and the third oil cylinder (21) are pushed to extend outward. When the first oil port (101) and the third oil port (103) are filled with oil at the same time, the piston rods of the first oil cylinder (11) and the third oil cylinder (21) are pushed to align and reset.

3. A centering steering system according to claim 2, characterized in that: The second oil cylinder (12) and the fourth oil cylinder (22) both comprise a fourth oil port (104) and a fifth oil port (105). When the fourth oil port (104) is filled with oil, the piston rods of the second oil cylinder (12) and the fourth oil cylinder (22) are pushed outward. When the fifth oil port (105) is filled with oil, the piston rods of the second oil cylinder (12) and the fourth oil cylinder (22) are pushed back.

4. A centering steering system according to claim 2, characterized in that: The first oil cylinder (11) and the third oil cylinder (21) both comprise a cylinder body (201), wherein the cylinder body (201) is provided with an end cover (202), a positioning ring (203) and a bottom plate (204) in sequence. A first piston (205) is sleeved on a piston rod in the cylinder body (201), and the first piston (205) is limitedly positioned between the end cover (202) and the positioning ring (203). A second piston (206) is limitedly slidable between the positioning ring (203) and the bottom plate (204) in the cylinder body (201), and the second piston (206) is provided with a push rod (207) for pushing the piston rod.

5. The centering steering system according to claim 3, characterized in that: The first reversing valve (5) comprises 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 reversing valve (7); the second front valve (52) can be switched to disconnect or connect the third reversing 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); and the third front valve (53) can be switched to disconnect or connect the steering gear (4) to the second reversing valve (6).

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

7. The centering steering system according to claim 6, characterized in that: The third reversing valve (7) comprises 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 oil cylinder (21) and the fifth oil port (105) of the fourth oil cylinder (22); and the third rear valve (73) can be switched to disconnect or connect the first reversing valve (5) and the fourth reversing valve (8).

8. The centering steering system according to claim 7, 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 oil cylinder (21), and 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 oil cylinder (22). 104), the sixth rear valve (86) can be switched to an open circuit or the third oil port (103) of the third oil cylinder (21) can return oil and unload, the seventh rear valve (87) can be switched to an open circuit or the fourth oil port (104) of the fourth oil cylinder (22) can return oil and unload, and the eighth rear valve (88) can be switched to an open circuit 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 and unload.

9. The centering steering system according to claim 1, characterized in that: The conversion valve assembly (3) comprises 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 an 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 an open circuit or connected to both the front steering axle (1) and the rear steering axle (2) to simultaneously drive the front steering axle (1) and the rear steering axle (2) to be centered; the third solenoid valve (33) can be switched to an open circuit or connected to both the front steering axle (1) and the rear steering axle (2) to simultaneously lock the front steering axle (1) and the rear steering axle (2) to be centered.

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

Images