Bidirectional driving four-wheel multifunctional hydraulic control method

Abstract

The application discloses a bidirectional driving four-wheel multifunctional hydraulic control method, which comprises a hydraulic control method for controlling driving when a front cab, a hydraulic control method for controlling circle turning when the front cab, a hydraulic control method for controlling driving when a rear cab and a hydraulic control method for controlling circle turning when the rear cab. The switching of multiple oil paths is realized through the opening and closing of a valve group, so that the front axle or the rear axle steering function can be controlled by one cab, and the problem of single steering function is solved. Meanwhile, the position sensor is arranged to realize the automatic identification of the position of a steering oil cylinder and the automatic tire correction centering. In addition, the circle turning function is increased. The hydraulic control method provided by the application can quickly switch the driving mode and simplify the steering operation steps.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control, and more particularly to a two-way driving four-wheel multi-functional hydraulic control method. Background Technology

[0002] A hydraulic control system is based on an electric motor as the power source. It uses a hydraulic pump to convert mechanical energy into pressure, which drives hydraulic oil. By controlling various valves to change the flow direction of the hydraulic oil, it drives the hydraulic cylinder to make different strokes and directions of movement, thus completing the different action requirements of various equipment.

[0003] Currently, the application of two-way driving four-wheel hydraulic systems typically includes two cabs: a front cab and a rear cab. When the driver is operating the vehicle, typically when driving the front axle, they first operate the steering gear in the rear cab to center the rear axle steering cylinders, achieving tire centering. Then, they operate the steering gear in the front cab to control the front axle steering cylinders, steer the vehicle's front axle. Similarly, when driving the rear axle, they first operate the steering gear in the front cab to center the front axle steering cylinders, achieving tire centering, and then operate the steering gear in the rear cab to control the front axle steering cylinders, steer the vehicle's front axle. This requires the driver to frequently switch between cabs to perform specific operations that can only be performed in a specific cab. Furthermore, the steering function is extremely limited, and centering is very slow, making this control method extremely cumbersome. Summary of the Invention

[0004] In view of this, the present invention provides a two-way driving four-wheel multi-functional hydraulic control method, which aims to solve the technical problems of single steering function and cumbersome operation.

[0005] To solve the above technical problems, the technical solution of the present invention is to provide a two-way driving four-wheel multi-functional hydraulic control method, including a hydraulic control method for controlling driving from the front cab, a hydraulic control method for controlling turning from the front cab, a hydraulic control method for controlling driving from the rear cab, and a hydraulic control method for controlling turning from the rear cab.

[0006] Optionally, the hydraulic control method for controlling driving from the front cab, the hydraulic control method for controlling rotation from the front cab, the hydraulic control method for controlling driving from the rear cab, and the hydraulic control method for controlling rotation from the rear cab are achieved by switching the hydraulic circuit by controlling the opening and closing of a valve group; the valve group includes a first valve, a second valve, a third valve, a fourth valve, a fifth valve, and a sixth valve, and the sixth valve includes a first switch and a second switch.

[0007] Optionally, the hydraulic control method for controlling driving from the front cab includes:

[0008] By controlling the opening of the first and second valves and the closing of the third, fourth, fifth, and sixth valves, the hydraulic steering gear in the front cab is rotated, driving the piston rod of the front axle cylinder to move left and right, thereby turning the front axle left and right.

[0009] Optionally, after the front axle is steered, it further includes:

[0010] Control the third, fourth, and fifth valves to lock the rear axle steering cylinder.

[0011] Optionally, the hydraulic control method for controlling driving from the rear cab includes:

[0012] By controlling the opening of the third and fourth valves and the closing of the first, second, fifth, and sixth valves, the hydraulic steering gear in the rear cab is rotated, driving the piston rod of the rear axle cylinder to move left and right, thereby turning the rear axle left and right.

[0013] Optionally, after the rear axle is steered, it further includes:

[0014] Control the first valve, second valve, and fifth valve to lock the front axle steering cylinder.

[0015] Optionally, the step of performing left and right steering on the front axle or left and right steering on the rear axle further includes:

[0016] The position information of the steering cylinder is detected in real time using a position sensor;

[0017] Based on the position information of the steering cylinder, the valve assembly is controlled to open and close, thereby centering the drive wheels. Specifically:

[0018] If the position sensor detects that the rear axle steering cylinder is in the left-hand position when the front axle is turning left or right, the first switches of the first, second, fifth, and sixth valves are all closed, and the second switches of the third, fourth, and sixth valves are all opened, so that the rear axle steering cylinder controls the rear axle drive wheel to turn right until the position sensor detects that the rear axle steering cylinder is in the middle position, and the second switch of the sixth valve is closed, so that the rear axle drive wheel is centered.

[0019] If the position sensor detects that the rear axle steering cylinder is in the right-hand position when the front axle is turning left or right, the second switches of the first, second, fifth, and sixth valves are all closed, and the first switches of the third, fourth, and sixth valves are all opened, so that the rear axle steering cylinder controls the rear axle drive wheel to turn to the left until the position sensor detects that the rear axle steering cylinder is in the middle position, and the first switch of the sixth valve is closed, so that the rear axle drive wheel is centered.

[0020] If the position sensor detects that the front axle steering cylinder is in the left-hand position when the rear axle is turning left or right, the first switches of the third, fourth, fifth, and sixth valves are all closed, and the second switches of the first, second, and sixth valves are all opened, so that the front axle steering cylinder controls the front axle drive wheel to turn right until the position sensor detects that the front axle steering cylinder is in the middle position, and the second switch of the sixth valve is closed, thus completing the centering of the front axle drive wheel;

[0021] If the position sensor detects that the front axle steering cylinder is in the right-hand position when the rear axle is turning left or right, the second switches of the third, fourth, fifth, and sixth valves are all closed, and the first switches of the first, second, and sixth valves are all opened, so that the front axle steering cylinder controls the front axle drive wheel to turn left until the position sensor detects that the front axle steering cylinder is in the middle position, and the first switch of the sixth valve is closed, thus completing the centering of the front axle drive wheel.

[0022] Optionally, the hydraulic control method for controlling the rotation of the front cab includes:

[0023] By controlling the first, third, and fifth valves to be open and the second, fourth, and sixth valves to be closed, the hydraulic steering system is controlled to simultaneously drive the piston rods of the front axle steering cylinder and the rear axle steering cylinder to rotate, so that the whole vehicle can make a turning motion.

[0024] Optionally, the hydraulic control method for controlling the rotation of the rear cab includes:

[0025] By controlling the second, fourth, and fifth valves to be open and the first, third, and sixth valves to be closed, the hydraulic steering system is controlled to simultaneously drive the piston rods of the front axle steering cylinder and the rear axle steering cylinder to rotate, so that the whole vehicle can make a turning motion.

[0026] Optionally, before the vehicle performs the turning motion, it further includes:

[0027] Perform front axle drive wheel alignment and rear axle drive wheel alignment.

[0028] This invention provides a two-way driving four-wheel multi-functional hydraulic control method, including a hydraulic control method for controlling driving from the front cab, a hydraulic control method for controlling steering from the front cab, a hydraulic control method for controlling driving from the rear cab, and a hydraulic control method for controlling steering from the rear cab. Multiple hydraulic circuits are switched by opening and closing valve groups, allowing a single cab to independently control the steering function of the front or rear axle, solving the problem of limited steering functionality. Simultaneously, a position sensor is used to automatically identify the position of the steering cylinder and automatically perform tire alignment. Furthermore, a stationary steering function is added. The hydraulic control method provided by this invention enables rapid switching of driving modes, simplifying steering operation steps. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the hydraulic circuit of a two-way driving four-wheel multi-functional hydraulic control method provided in an embodiment of the present invention;

[0031] Figure 2 This is a control schematic diagram of a two-way driving four-wheel multi-functional hydraulic control method provided in an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the normal state of front and rear wheel alignment in a rotating mode provided by an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of an abnormal state of the front and rear wheelsets in a rotating mode provided by an embodiment of the present invention.

[0034] Figure 5 This is a control schematic diagram of a two-way driving four-wheel multi-functional hydraulic control method provided in another embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the embodiments of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This embodiment provides a two-way driving four-wheel multi-functional hydraulic control method. Its principle is to add several valve groups to the electrical oil circuit to switch the oil circuit, so that different oil circuits can be controlled to achieve different functions. Specifically, it includes a hydraulic control method for controlling driving from the front cab, a hydraulic control method for controlling turning from the front cab, a hydraulic control method for controlling driving from the rear cab, and a hydraulic control method for controlling turning from the rear cab.

[0037] Reference Figure 1 This is a schematic diagram of the hydraulic circuit of a two-way driving four-wheel multi-functional hydraulic control method provided in this embodiment.

[0038] In the hydraulic control system of this embodiment, there are front axle steering cylinder 1, rear axle steering cylinder 2, front cab hydraulic steering gear 3, rear cab hydraulic steering gear 4, hydraulic pump 5, front axle cylinder position sensor 6, rear axle cylinder position sensor 7, first valve 8, second valve 9, third valve 10, fourth valve 11, fifth valve 12, and sixth valve 13, wherein the sixth valve includes a first switch 7DT and a second switch 8DT.

[0039] The switching of each oil circuit is achieved by controlling the opening and closing of each valve in the valve group. The principle of each actuating oil circuit includes the following states:

[0040] Front wheel steering mode: Open the first and second valves, and close the third, fourth, fifth, and sixth valves. The R / L ports of the front cab hydraulic steering unit are connected in parallel with the L / R ports of the rear cab hydraulic steering unit, respectively. These ports are then directly connected to the front axle steering cylinder via the first and second valves. This ensures that operating either the front or rear cab hydraulic steering unit independently will drive the piston rod of the front axle steering cylinder to move left or right, thus achieving left and right steering of the front axle.

[0041] It should be noted that the rear axle steering cylinder must be locked through the third, fourth, and fifth valves to prevent the rear axle from running during driving.

[0042] Rear wheel steering mode: Open valves three and four, close valves one, two, five, and six. The R / L ports of the front cab hydraulic steering unit are connected in parallel with the L / R ports of the rear cab hydraulic steering unit, respectively, and directly connected to the rear axle steering cylinder through valves three and four. This ensures that operating either the front or rear cab hydraulic steering unit independently will drive the piston rod of the rear axle steering cylinder to move left or right, thus achieving left and right steering of the rear axle.

[0043] It should be noted that the front axle steering cylinder must be locked through the first valve, the second valve, and the fifth valve to prevent the front axle from veering off course during operation of the equipment in the rear axle cab.

[0044] Rear wheel alignment status: When the front or rear cab hydraulic steering gear is not operated, both the R and L ports of the hydraulic steering gear are closed, so the rear wheels will not rotate. At this time, controlling the first and second switches of the sixth valve allows the piston rod of the rear axle steering cylinder to move left or right, thereby controlling the alignment of the rear axle drive wheels. By adding a front axle steering cylinder position sensor to the front axle steering cylinder and a rear axle steering cylinder position sensor to the rear axle steering cylinder, the position of the steering cylinder is determined, thus determining the specific opening and closing status of the first and second switches of the sixth valve.

[0045] If the rear axle steering cylinder position sensor detects that the steering cylinder is on the left, the second switch of the third valve and the sixth valve are opened, and the first switch of the sixth valve is closed. This allows the hydraulic pump outlet oil to enter the left chamber of the rear axle steering cylinder through the sixth valve and the third valve. The rear axle steering cylinder then controls the drive wheel to turn to the right until the position sensor detects that the drive wheel is in the middle position. At this point, the second switch of the sixth valve is closed, thus aligning the rear axle steering cylinder and achieving rear axle drive wheel alignment.

[0046] If the rear axle steering cylinder position sensor detects that the steering cylinder is on the right side, the first switch of the fourth and sixth valves is opened, and the second switch of the sixth valve is closed, so that the hydraulic pump outlet oil enters the right chamber of the rear axle steering cylinder through the sixth and fourth valves. The rear axle steering cylinder then controls the drive wheel to turn to the left until the position sensor detects that the drive wheel is in the middle position. At this point, the first switch of the sixth valve is closed, thus aligning the rear axle steering cylinder and achieving rear axle drive wheel alignment.

[0047] Front axle alignment state: When the front or rear cab hydraulic steering gear is not operated, both the R and L ports of the hydraulic steering gear are closed, so the rear wheels will not rotate. At this time, controlling the first and second switches of the sixth valve allows the piston rod of the front axle steering cylinder to move left or right, thereby controlling the alignment of the front axle drive wheels. By adding a front axle steering cylinder position sensor to the front axle steering cylinder and a rear axle steering cylinder position sensor to the rear axle steering cylinder, the position of the steering cylinder is determined, thus determining the specific opening and closing status of the first and second switches of the sixth valve.

[0048] If the front axle steering cylinder position sensor detects that the steering cylinder is on the left, the second switch of the first valve and the sixth valve is opened, and the first switch of the sixth valve is closed, so that the hydraulic pump outlet oil enters the right chamber of the front axle steering cylinder through the sixth valve and the first valve. The front axle steering cylinder then controls the drive wheel to turn to the right until the position sensor detects that the drive wheel is in the middle position. At this point, the second switch of the sixth valve is closed, thus completing the centering of the front axle steering cylinder and achieving the centering of the front axle drive wheel.

[0049] If the front axle steering cylinder position sensor detects that the steering cylinder is on the right side, the first switch of the second valve and the sixth valve are opened, and the second switch of the sixth valve is closed, so that the hydraulic pump outlet oil enters the left chamber of the front axle steering cylinder through the sixth valve and the second valve. The front axle steering cylinder then controls the drive wheel to turn to the left until the position sensor detects that the drive wheel is in the middle position. At this point, the first switch of the sixth valve is closed, thus completing the centering of the front axle steering cylinder and achieving the centering of the front axle drive wheel.

[0050] Rotation state: Open the first, third, and fifth valves, and close the second, fourth, and sixth valves. The first port R and second port L of the front cab hydraulic steering gear are connected in parallel with the second port L and first port R of the rear cab hydraulic steering gear, respectively. When oil is discharged from the first port R of the front cab hydraulic steering gear, the hydraulic oil enters the left chamber of the front axle steering cylinder through the first valve, controlling the front drive wheels to turn right. At the same time, the hydraulic oil enters the fifth valve from the right chamber of the front axle steering cylinder, and then enters the left chamber of the rear axle steering cylinder, controlling the rear drive wheels to turn left. Simultaneously, the hydraulic oil returns from the right chamber of the rear axle steering cylinder through the third valve to the second port L of the front cab hydraulic steering gear, thus completing the oil circuit circulation and realizing the rotation action of the entire vehicle.

[0051] Therefore, operating the front cab hydraulic steering unit clockwise simultaneously drives the piston rods of the front axle steering cylinder to rotate in the R direction and the rear axle steering cylinder to rotate in the L direction, thus achieving a clockwise rotation of the entire vehicle. Similarly, operating the front cab hydraulic steering unit counterclockwise simultaneously drives the piston rods of the front axle steering cylinder to rotate in the L direction and the rear axle steering cylinder to rotate in the R direction, thus achieving a counterclockwise rotation of the entire vehicle. Furthermore, the first port R and the second port L of the front and rear cab hydraulic steering units are connected in parallel; operating the rear cab hydraulic steering unit simultaneously will similarly drive the entire vehicle to rotate.

[0052] It should be noted that the second and fourth valves need to be locked to prevent the front axle steering cylinder and the rear axle steering cylinder from rotating at different angles, which could cause the front or rear axle tires to slip and wear.

[0053] Furthermore, the second, fourth, and fifth valves can be opened, while the first, third, and sixth valves can be closed. This oil circuit is equivalent in principle to the oil circuit described above, the difference being that they are symmetrically connected, which will not be elaborated on here.

[0054] It should be noted that in this embodiment, the first valve and the third valve need to be locked to prevent the front axle steering cylinder and the rear axle steering cylinder from rotating at different angles, which could cause the front or rear axle tires to slip and wear.

[0055] This embodiment proposes a composition method for multiple oil circuits corresponding to different functions and explains the oil circuit principle. It not only solves the problem of single steering, but also enables automatic centering based on the oil circuit principle of this application. It also adds a turning function to realize a multi-functional driving mode. Furthermore, by opening, closing and locking each valve, the occurrence rate of problems during the operation of the equipment is reduced, tire wear is reduced, thereby improving driving safety and convenience and extending tire life.

[0056] Furthermore, based on the above explanation of the oil circuit principle, the embodiments of the control method will be described in detail.

[0057] As a preferred embodiment, such as Figure 2 As shown, the main controller controls all electrical components. A cab selection switch, a front cab mode selection switch, and a rear cab mode selection switch can be added to the front cab and the rear cab, respectively. The driver can operate the cab selection switch from any cab to select the cab, switching to the front or rear cab for operation. After the driver operates the cab selection switch to select the current cab, they can choose the front or rear cab mode, and then select the driving mode or the turning mode.

[0058] Specifically, when switching to the front cab for operation and switching to driving mode, the front axle tires need to be able to turn normally (i.e., the front axle steering cylinder is controlled by the front cab hydraulic steering unit to achieve steering), and the rear axle tires need to be fixed in the center position and remain stationary (i.e., the rear axle steering cylinder is in the center position). If the rear axle tires are not in the center position, it will cause uneven tire wear and different degrees of deviation during driving.

[0059] When the controller receives the driving mode signal, it first determines the position of the rear axle steering cylinder by using the position data detected in real time by the rear axle cylinder position sensor.

[0060] If the rear axle steering cylinder is in the left-hand position, the control system opens the second switches of the third, fourth, and sixth valves, and closes the first switches of the first, second, fifth, and sixth valves to achieve rear wheel alignment. After automatic alignment is completed, the second switch of the sixth valve is closed.

[0061] If the rear axle steering cylinder is in the right-hand position, the control system opens the first switch of the third, fourth, and sixth valves, and closes the second switches of the first, second, fifth, and sixth valves to achieve rear wheel alignment. After automatic alignment is completed, the first switch of the sixth valve is closed.

[0062] If the rear axle steering cylinder is in the middle position, automatic alignment is not required.

[0063] After the rear wheels are automatically aligned, the first and second valves open, while the third, fourth, fifth, and sixth valves close, putting the hydraulic circuit into front wheel steering mode and enabling normal driving. This completes the switching of the driving mode, allowing the driver to operate the vehicle normally. From the moment the driver presses the mode selection switch in the cab to switch to driving mode, the control system completes the switching of the hydraulic circuits and automatic tire alignment in approximately 2 seconds, significantly reducing the difficulty and complexity of operation. Furthermore, the addition of sensors ensures more precise tire alignment, reducing wear caused by misalignment.

[0064] Furthermore, when the controller receives the turning mode signal, it first needs to confirm that the front and rear axle tires can steer normally in opposite directions. Simultaneously, it must ensure that both front and rear axle tires are in the center position before steering. Otherwise, one axle will reach its limit position before the other, resulting in insufficient turning radius and inconsistent angles between the front and rear axle steering cylinders, causing tire slippage and wear. The normal operating condition is referenced... Figure 3 As shown, abnormal state reference Figure 4 As shown.

[0065] Furthermore, using the real-time position data detected by the rear axle cylinder position sensor, the position of the rear axle steering cylinder is determined, and the aforementioned automatic alignment is performed. After the rear axle is automatically aligned, the real-time position data detected by the front axle cylinder position sensor is used to determine the position of the front axle steering cylinder, and the aforementioned automatic alignment is performed.

[0066] After automatic alignment of the front and rear wheels, the first, third, and fifth valves are opened, while the second, fourth, and sixth valves are closed, causing the hydraulic circuit to rotate in place, achieving normal rotation function. Compared to driving mode, because the tires are in a "figure-eight" shape, the turning radius is greatly reduced, allowing for rotation within a certain radius. This makes it easier for engineering vehicles to turn and pass through narrow roads and alleys, and more flexible and easier to control when parking. During this period, from the time the driver presses the cab mode selection switch to rotation mode, the control system can complete the switching of the state of each hydraulic circuit and automatic tire alignment in about 3 to 4 seconds. Compared with traditional solutions, this greatly reduces the difficulty and complexity of operation. In addition, the addition of sensors can make the tires more accurately centered, reducing wear caused by tire misalignment.

[0067] Furthermore, when switching to the rear cab for operation, the operating principle is the same as that of the front cab, the difference being that the oil circuit in the rear cab's driving and turning states is used to control the rear cab's driving and turning. This will not be elaborated upon further here.

[0068] As a preferred embodiment, a host computer can also be added to the control system, namely, instruments in the front cab and instruments in the rear cab, such as... Figure 5 As shown, the opening and closing information of each valve and the real-time position information of the position sensor received by the main controller allow the driver to monitor the control status and oil circuit switching status in real time through the instrument panel in the front or rear cab. If an error or equipment failure occurs, the location and cause of the failure can be detected in time, so that the operator can handle and maintain it immediately.

[0069] Based on the detailed description of the above embodiments, this control method can be operated from any cab. Depending on the different operating modes selected, the control system automatically determines the position and controls the front and rear axle wheel directions, achieving automatic alignment of the front and rear wheels before driving. This avoids misalignment of the front and rear wheels during driving, which can lead to tire deviation, abnormal tire wear, and premature damage, further reducing the incidence of safety accidents. In addition, the added stationary turning function makes the driving mode more versatile, enabling driving in narrow passages. It can achieve the purpose of turning in right-angle bends in narrow passages without the need for U-turns.

[0070] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0071] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A two-way driving four-wheel multi-functional hydraulic control method, characterized in that, This includes hydraulic control methods for controlling driving from the front cab, hydraulic control methods for controlling rotation from the front cab, hydraulic control methods for controlling driving from the rear cab, and hydraulic control methods for controlling rotation from the rear cab. The hydraulic control method for controlling driving from the front cab, the hydraulic control method for controlling rotation from the front cab, the hydraulic control method for controlling driving from the rear cab, and the hydraulic control method for controlling rotation from the rear cab are achieved by switching the hydraulic circuit by controlling the opening and closing of the valve group; the valve group includes a first valve, a second valve, a third valve, a fourth valve, a fifth valve, and a sixth valve, and the sixth valve includes a first switch and a second switch. The hydraulic control method for controlling driving from the front cab includes: By controlling the opening of the first and second valves and the closing of the third, fourth, fifth, and sixth valves, the hydraulic steering gear in the front cab is rotated, which drives the piston rod of the front axle steering cylinder to move left and right, so that the front axle can turn left and right. The hydraulic control method for controlling driving from the rear cab includes: By controlling the opening of the third and fourth valves and the closing of the first, second, fifth, and sixth valves, the hydraulic steering gear in the rear cab is rotated, which drives the piston rod of the rear axle steering cylinder to move left and right, so that the rear axle can turn left and right. The left-right steering of the front axle or the left-right steering of the rear axle also includes: The position information of the steering cylinder is detected in real time using a position sensor; Based on the position information of the steering cylinder, the valve assembly is controlled to open and close, thereby centering the drive wheels. Specifically: If the position sensor detects that the rear axle steering cylinder is in the left-hand position when the front axle is turning left or right, the first switches of the first, second, fifth, and sixth valves are all closed, and the second switches of the third, fourth, and sixth valves are all opened, so that the rear axle steering cylinder controls the rear axle drive wheel to turn right until the position sensor detects that the rear axle steering cylinder is in the middle position, and the second switch of the sixth valve is closed, so that the rear axle drive wheel is centered. If the position sensor detects that the rear axle steering cylinder is in the right-hand position when the front axle is turning left or right, the second switches of the first, second, fifth, and sixth valves are all closed, and the first switches of the third, fourth, and sixth valves are all opened, so that the rear axle steering cylinder controls the rear axle drive wheel to turn to the left until the position sensor detects that the rear axle steering cylinder is in the middle position, and the first switch of the sixth valve is closed, so that the rear axle drive wheel is centered. If the position sensor detects that the front axle steering cylinder is in the left-hand position when the rear axle is turning left or right, the first switches of the third, fourth, fifth, and sixth valves are all closed, and the second switches of the first, second, and sixth valves are all opened, so that the front axle steering cylinder controls the front axle drive wheel to turn right until the position sensor detects that the front axle steering cylinder is in the middle position, and the second switch of the sixth valve is closed, thus completing the centering of the front axle drive wheel; If the position sensor detects that the front axle steering cylinder is in the right-hand position when the rear axle is turning left or right, the second switches of the third, fourth, fifth, and sixth valves are all closed, and the first switches of the first, second, and sixth valves are all opened, so that the front axle steering cylinder controls the front axle drive wheel to turn to the left until the position sensor detects that the front axle steering cylinder is in the middle position, and the first switch of the sixth valve is closed, thus completing the centering of the front axle drive wheel; Specifically, the R / L ports of the front cab hydraulic steering unit are connected in parallel with the L / R ports of the rear cab hydraulic steering unit. The R / L ports of the front cab hydraulic steering unit are connected to the left / right chamber of the front axle steering cylinder via a first valve and a second valve, respectively. The R / L ports of the rear cab hydraulic steering unit are connected to the right / left chamber of the rear axle steering cylinder via a third valve and a fourth valve, respectively. The fifth valve is connected to the right chamber of the front axle steering cylinder and the left chamber of the rear axle steering cylinder; The sixth valve is connected to the hydraulic pump, and also to the R / L ports of the front cab hydraulic steering gear and the rear cab hydraulic steering gear.

2. The bidirectional driving four-wheel multi-functional hydraulic control method according to claim 1, characterized in that, The hydraulic control method for controlling the rotation of the front cab includes: By controlling the first, third, and fifth valves to be open and the second, fourth, and sixth valves to be closed, the hydraulic steering system is controlled to simultaneously drive the piston rods of the front axle steering cylinder and the rear axle steering cylinder to move, so that the vehicle can make a turning motion.

3. The bidirectional driving four-wheel multi-functional hydraulic control method according to claim 1, characterized in that, The hydraulic control method for controlling the rotation of the rear cab includes: By controlling the second, fourth, and fifth valves to be open and the first, third, and sixth valves to be closed, the hydraulic steering system is controlled to simultaneously drive the piston rods of the front axle steering cylinder and the rear axle steering cylinder to rotate, so that the whole vehicle can make a turning motion.

4. A two-way driving four-wheel multi-functional hydraulic control method according to claim 2 or 3, characterized in that, Before the vehicle performs the turning motion, it also includes: Perform front axle drive wheel alignment and rear axle drive wheel alignment.

Images