Engineering vehicle and steering control method thereof

Abstract

This invention discloses an engineering vehicle and its steering control method. The engineering vehicle includes: a frame; an axle connected to the frame; a steering wheel assembly including a steering wheel that is pivotally connected to the axle via a steering knuckle; a first tie rod, the first end of which is hinged to the steering knuckle for pulling the steering knuckle to pivot relative to the axle to turn the steering wheel, the length of the first tie rod being less than the radius of the steering wheel; a rocker arm hinged to the frame, the hinge point of the rocker arm and the frame being higher than the hinge point of the first tie rod and the steering knuckle, the rocker arm being hinged to the second end of the first tie rod; a second tie rod, the first end of which is hinged to the rocker arm; and a steering drive mechanism disposed on the frame, including a drive unit and a rocker arm whose first end and the second end of the second tie rod are hinged together, the second end of the rocker arm being connected to the drive unit, the drive unit being used to drive the rocker arm to pivot to turn the steering wheel.

Description

Technical Field

[0001] This invention relates to the field of emergency rescue technology, and in particular to an engineering vehicle and its steering control method. Background Technology

[0002] Engineering vehicles are a backbone of construction projects, significantly accelerating progress and greatly reducing manpower requirements. Their applications are wide-ranging, including transportation, excavation, repair, emergency rescue, and even combat. Emergency rescue for major industrial accidents and natural disasters is a social disaster reduction and relief effort undertaken both domestically and internationally in recent years. Engineering vehicles used for emergency rescue can enhance the ability to handle major industrial accidents and natural disasters, playing a crucial role in saving lives, property, and mitigating environmental damage. When performing rescue missions, emergency rescue vehicles often need to operate in harsh road conditions and dangerous environments, working in confined spaces; a larger tire turning angle improves the overall safety and working capacity of the vehicle. Summary of the Invention

[0003] The purpose of this invention is to provide an engineering vehicle that can increase the steering angle of the steering wheels and a steering control method thereof.

[0004] The first aspect of this invention discloses an engineering vehicle, comprising:

[0005] Frame;

[0006] The axle is connected to the vehicle frame;

[0007] A steering wheel assembly, including a steering wheel pivotally connected to the axle via a steering knuckle relative to the axle;

[0008] A first tie rod, the first end of which is hinged to the steering knuckle, is used to pull the steering knuckle to swing relative to the axle so that the steering wheel turns. The length of the first tie rod is less than the radius of the steering wheel.

[0009] A rocker arm is hinged to the vehicle frame. The hinge point where the rocker arm is hinged to the vehicle frame is higher than the hinge point where the first tie rod is hinged to the steering knuckle. The rocker arm is hinged to the second end of the first tie rod.

[0010] The second pull rod has its first end hinged to the rocker arm;

[0011] A steering drive mechanism, mounted on the vehicle frame, includes a drive unit and a rocker arm hinged to a first end and a second end of a second tie rod. The second end of the rocker arm is connected to the drive unit, and the drive unit is used to drive the rocker arm to swing in order to steer the steering wheel.

[0012] In some embodiments, a steering wheel is also included, and the drive unit includes a power steering system that drives a connection between the steering wheel and the rocker arm.

[0013] In some embodiments, the steering wheel assembly further includes a pressure detection sensor, a first angle detection sensor for detecting the steering angle of the steering wheel, and a steering cylinder for driving the steering wheel to steer. The steering cylinder has a first chamber and a second chamber. Pressurized oil is supplied to the first chamber, and the steering cylinder drives the steering wheel to steer in a first direction. Pressurized oil is supplied to the second chamber, and the steering cylinder drives the steering wheel to steer in a second direction opposite to the first direction. The engineering vehicle further includes a steering hydraulic system and a control device signal-connected to the steering hydraulic system and the first angle detection sensor. The power steering system includes... A first directional valve is connected to the steering wheel drive. The steering hydraulic system includes a hydraulic pump, a tank, a first valve and a second valve connected to the control device via signals. The first directional valve is connected between the hydraulic pump and the steering cylinder. The first directional valve has a first valve position that allows hydraulic oil output from the hydraulic pump to flow into a first chamber of the steering cylinder, and a second valve position that allows hydraulic oil output from the hydraulic pump to flow into a second chamber of the steering cylinder. When the steering wheel is rotated in a third direction, it drives the first directional valve to switch to the first valve position and drives the power steering unit to drive the rocker arm along a fifth direction. When the steering wheel rotates in a fourth direction opposite to the third direction, it drives the first directional control valve to switch to its second position and drives the power steering system to drive the rocker arm to swing in a sixth direction opposite to the fifth direction. The first valve connects the oil tank to the pipeline between the hydraulic pump and the first directional control valve. The second valve connects the inlet and outlet of the hydraulic pump. The first valve has a first valve position and a second valve position. In the first valve position, the first valve disconnects the pipeline between the oil tank and the hydraulic pump and the first directional control valve. In the second valve position, the... The pipeline between the oil tank, the hydraulic pump, and the first directional valve is connected through a throttle port. The second valve has a first valve position and a second valve position. In the first valve position, the second valve disconnects the connection between the inlet and outlet of the hydraulic pump. In the second valve position, the inlet and outlet of the hydraulic pump are directly connected through the second valve. The pressure detection sensor is used to detect the pressure of the hydraulic oil in the pipeline between the first valve and the first directional valve. The control device controls the valve position switching of the first valve and the second valve based on the detection results of the first angle detection sensor and the pressure detection sensor.

[0014] In some embodiments, a second angle detection sensor is further included to detect the angle of the steering wheel, and the control device controls the valve position switching of the first valve and the second valve based on the detection results of the first angle detection sensor and the second angle detection sensor.

[0015] In some embodiments, the first directional valve further has a first directional valve third position that connects the oil chamber of the steering cylinder to which it is connected to the oil tank, and drives the first directional valve to switch to the first directional valve third position when the steering wheel is not turned.

[0016] In some embodiments, in the third valve position of the first reversing valve, the first chamber and the second chamber of the reversing cylinder are both connected to the oil tank.

[0017] A second aspect of the present invention discloses a steering control method for any of the engineering vehicles described above, comprising: controlling the valve position switching of the first valve and the second valve based on the detection results of the first angle detection sensor and the pressure detection sensor.

[0018] In some embodiments, the steering wheel has a first limit steering angle for rotation in a first direction and a second limit steering angle for rotation in a second direction; during steering, the first angle detection sensor detects that the difference between the steering angle of the steering wheel in the first direction and the first limit steering angle is greater than a first threshold angle, the steering angle of the steering wheel in the first direction remains unchanged, and the pressure of the hydraulic oil detected by the pressure sensor continues to increase after the steering angle of the steering wheel in the first direction remains unchanged and continues to increase for a first threshold time. After the first threshold time has elapsed, the first valve is controlled to switch to the second valve position of the first valve, and after the first valve switches to the second valve position... After the second threshold time has elapsed, the second valve is controlled to switch to the second valve position. During steering, the first angle detection sensor detects that the difference between the steering angle of the steering wheel rotating in the second direction and the second limit steering angle is greater than the second threshold angle. The steering angle of the steering wheel rotating in the second direction remains unchanged, and the pressure of the hydraulic oil detected by the pressure sensor continues to increase after the steering angle of the steering wheel rotating in the second direction remains unchanged, and continues to increase for a third threshold time. After the third threshold time has elapsed, the first valve is controlled to switch to the second valve position. After the first valve has switched to the second valve position for a fourth threshold time, the second valve is controlled to switch to the second valve position.

[0019] In some embodiments, the steering wheel has a first limit steering angle for rotation in a first direction and a second limit steering angle for rotation in a second direction; when steering, the first angle detection sensor detects that the difference between the steering angle of the steering wheel rotating in the first direction and the first limit steering angle is equal to a first threshold angle, and controls the first valve to switch to the second valve position; and after the first angle detection sensor detects that the steering angle of the steering wheel rotating in the first direction is equal to the first limit steering angle, controls the second valve to switch to the second valve position; when steering, the first angle detection sensor detects that the difference between the steering angle of the steering wheel rotating in the second direction and the second limit steering angle is equal to a second threshold angle, and controls the first valve to switch to the second valve position; and after the first angle detection sensor detects that the steering angle of the steering wheel rotating in the second direction is equal to the second limit steering angle, controls the second valve to switch to the second valve position.

[0020] Based on the engineering vehicle provided by the present invention, by setting a rocker arm hinged to the vehicle frame, the first tie rod is connected to the rocker arm, the second tie rod and the rocker arm of the steering drive mechanism, so that the length of the first tie rod is less than the radius of the steering wheel, thereby reducing the interference of the first tie rod on the steering range of the steering wheel and increasing the maximum steering angle of the steering wheel.

[0021] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic diagram of a portion of the structure of the engineering vehicle in this embodiment of the present invention;

[0024] Figure 2 for Figure 1 A top view of the structure shown;

[0025] Figure 3 for Figure 2 A schematic diagram of the structure of the steering wheel after it has turned, as shown in the diagram.

[0026] Figure 4 This is a schematic diagram of the steering wheel according to an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram illustrating the structural principle of the steering hydraulic system according to an embodiment of the present invention. Detailed Implementation

[0028] 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. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0029] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0030] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0033] like Figures 1 to 4 As shown, the engineering vehicle in this embodiment includes a frame 10, an axle, a steering wheel assembly, a first tie rod 11, a rocker arm 13, a second tie rod 12, and a steering drive mechanism.

[0034] The axle is connected to the frame 10, and the steering wheel assembly includes a steering wheel 19 that is pivotally connected to the axle via a steering knuckle 16. The steering wheel 19 achieves steering by pivoting relative to the axle.

[0035] The first end of the first tie rod is hinged to the steering knuckle 16. The first tie rod 11 is used to pull the steering knuckle 16 to swing relative to the axle so that the steering wheel 19 turns. The length of the first tie rod 11 is less than the radius of the steering wheel 19.

[0036] The rocker arm 13 is hinged to the frame 10. The hinge point between the rocker arm 13 and the frame 10 is higher than the hinge point between the first tie rod 11 and the steering knuckle 16. The rocker arm 13 is hinged to the second end of the first tie rod. The first end of the second tie rod is hinged to the rocker arm 13.

[0037] The steering drive mechanism is mounted on the frame 10. The steering drive mechanism includes a drive unit and a rocker arm 14. The first end of the rocker arm is hinged to the second end of the second pull rod. The second end of the rocker arm is connected to the drive unit. The drive unit is used to drive the rocker arm 14 to swing so as to steer the steering wheel 19.

[0038] During operation, the drive unit drives the rocker arm 14 to swing, such as... Figure 1In the illustrated embodiment, when the rocker arm 14 swings clockwise, it pulls the second lever 12, which in turn pulls the rocker arm 13 to swing. The rocker arm 13 then pushes the first lever 11, which in turn pushes the steering knuckle, thereby turning the steering wheel 19. When the rocker arm 14 swings counterclockwise, it pushes the second lever 12, which in turn pushes the rocker arm 13 to swing. The rocker arm 13 then pulls the first lever 11, which in turn pulls the steering knuckle, thereby turning the steering wheel 19.

[0039] In existing engineering vehicles, the steering wheels are hinged to a steering knuckle and a first tie rod, which in turn is directly hinged to a rocker arm. The rocker arm's swing directly pulls or pushes the first tie rod, which in turn pulls or pushes the steering knuckle, causing the steering wheels to steer. Because existing engineering vehicles lack a rocker arm and second tie rod structure, the first tie rod is directly connected to the rocker arm. The first tie rod is very long, approaching or even exceeding the length of the steering wheel. Its radial extension along the steering wheel is significant, causing interference from the first tie rod at the steering wheel's limit steering position, thus affecting its maximum steering angle.

[0040] In this embodiment, the engineering vehicle is hinged to the frame 10 by a rocker arm 13. The first tie rod 11 is connected to the rocker arm 13, the second tie rod 12 and the rocker arm 14 of the steering drive mechanism. The length of the first tie rod 11 is less than the radius of the steering wheel 19, thereby reducing the interference of the first tie rod 11 on the steering range of the steering wheel 19 and increasing the maximum steering angle of the steering wheel 19.

[0041] In some embodiments, the engineering vehicle further includes a steering wheel 17, and a drive unit including a power steering system 15 driving a connection between the steering wheel 17 and the rocker arm 14. In the embodiment shown, the power steering system includes a hydraulic power steering system. In some embodiments not shown, the power steering system includes an electric power steering system. In the embodiment shown, when steering, the steering wheel 17 is turned, and the steering wheel 17 transmits torque to the power steering system via a steering drive shaft 171. The power steering system transmits the torque of the steering wheel to the rocker arm and also additionally assists in driving the rocker arm to swing.

[0042] In some embodiments, such as Figure 5As shown, the steering wheel assembly also includes a pressure detection sensor 21, a first angle detection sensor 22 for detecting the steering angle of the steering wheel 19, and a steering cylinder 23 for driving the steering wheel 19 to steer. The steering cylinder 23 has a first chamber and a second chamber; in the embodiment shown, the first chamber and the second chamber are a rod-mounted chamber and a rodless chamber, respectively. Pressurized oil is supplied to the first chamber, and the steering cylinder 23 drives the steering wheel 19 to steer in a first direction. Pressurized oil is supplied to the second chamber, and the steering cylinder 23 drives the steering wheel 19 to steer in a second direction opposite to the first direction; when the first direction is clockwise, the second direction is counterclockwise. The engineering vehicle also includes a steering hydraulic system and a control device 24 signal-connected to the steering hydraulic system and the first angle detection sensor 22. The power steering system includes a first directional valve 251 drively connected to the steering wheel 17, and the steering hydraulic system includes a hydraulic pump 27, an oil tank 28, a first valve 261 and a second valve 262 signal-connected to the control device 24. The first directional valve 251 is connected between the hydraulic pump 27 and the steering cylinder 23. The first directional valve 251 has a first valve position that allows the hydraulic oil output by the hydraulic pump 27 to flow into the first chamber of the steering cylinder 23, and a second valve position that allows the hydraulic oil output by the hydraulic pump 27 to flow into the second chamber of the steering cylinder 23. In the embodiment shown in the figure, the first directional valve is a three-position four-way directional valve. The first directional valve has a first oil port located on the upper left, a second oil port located on the upper right, a third oil port located on the lower left, and a fourth oil port located on the lower right. In the left valve position of the first directional valve, its first oil port and fourth oil port are connected, and its second oil port and third oil port are connected. In the right valve position of the first directional valve, its first oil port and third oil port are connected, and its second oil port and fourth oil port are connected. In the middle valve position of the first directional valve, all four oil ports are connected.

[0043] When the steering wheel 17 is rotated in a third direction, it drives the first directional control valve 251 to switch to the first valve position and drives the power steering unit 15 to drive the rocker arm 14 to swing in a fifth direction. When the steering wheel 17 is rotated in a fourth direction opposite to the third direction, it drives the first directional control valve 251 to switch to the second valve position and drives the power steering unit 15 to drive the rocker arm 14 to swing in a sixth direction opposite to the fifth direction. One of the third and fourth directional control valves rotates clockwise, and the other counterclockwise. One of the fifth and sixth directional control valves rotates clockwise, and the other counterclockwise. Figure 4As shown, the power steering system is a hydraulic power steering system. The first directional control valve of the hydraulic power steering system can switch between its first and second positions (i.e., the left and right positions as shown in the figure) according to the rotation of the steering wheel. When the steering wheel is not turned, it can switch to the intermediate position as shown in the figure. When the steering wheel is turned, the hydraulic power steering system can directly transmit the torque of the steering wheel to the rocker arm to drive its movement. It also uses hydraulic cylinders and other components to assist the rocker arm movement with the pressure of hydraulic oil. Furthermore, the valve position switching of the first directional control valve directly drives the steering cylinder to turn the steering wheel.

[0044] The first valve 261 is connected to the oil tank 28. The pipeline between the hydraulic pump 27 and the first directional valve 251 is connected to the first valve 261. The second valve 262 is connected to the inlet and outlet of the hydraulic pump 27. The first valve 261 has a first valve position and a second valve position. In the first valve position, the first valve 261 disconnects the pipeline between the oil tank 28 and the hydraulic pump 27 and the first directional valve 251, meaning that the pipeline between the hydraulic pump 27 and the first directional valve 251 is not directly connected to the oil tank 28 through the first valve 261. In the second valve position, the pipeline between the oil tank 28 and the hydraulic pump 27 and the first directional valve 251 is connected through a throttle orifice, meaning that the pipeline between the hydraulic pump 27 and the first directional valve 251 is directly connected to the oil tank 28 through the throttle orifice on the first valve 261. The pipeline between the hydraulic pump 27 and the first directional valve 251 is connected to the oil tank through a small back pressure, achieving pressure relief under a small pressure. The second valve 262 has a first valve position and a second valve position. In the first valve position, the second valve 262 disconnects the connection between the inlet and outlet of the hydraulic pump 27, meaning that the inlet and outlet of the hydraulic pump 27 are not directly connected through the second valve 262. In the second valve position, the inlet and outlet of the hydraulic pump 27 are directly connected through the second valve 262, meaning that the inlet and outlet of the hydraulic pump 27 are directly connected through the second valve 262. At this time, the second valve 262 acts as a flow pipe, and the hydraulic pump 27 directly depressurizes and does not output high-pressure hydraulic oil. The pressure detection sensor 21 is used to detect the pressure of the hydraulic oil in the pipeline between the first valve 261 and the first directional valve 251. The control device 24 controls the switching of the valve positions of the first valve 261 and the second valve 262 based on the detection results of the first angle detection sensor 22 and the pressure detection sensor 21, that is, controls the first valve 261 to switch between the first valve position and the first valve position, and controls the second valve 262 to switch between the first valve position and the second valve position. In this embodiment, when the engineering vehicle encounters an obstacle while turning, the steering wheel cannot turn further. At this time, the angle of the steering wheel detected by the first angle detection sensor cannot increase further and remains unchanged. The pressure detected by the pressure detection sensor gradually increases. At this time, the control device can determine that the steering wheel has encountered a steering obstacle and switch the first valve to the second valve position to firstly release the low pressure of the steering cylinder. Then, the second valve is switched to the second valve position to completely release the pressure of the steering cylinder. This can effectively buffer the steering cylinder and avoid damage and safety hazards to the entire steering system caused by high or continuously rising oil pressure when encountering a steering obstacle.

[0045] In some embodiments, as shown in the figure, the engineering vehicle includes two front wheels and two rear wheels 191, a rear steering cylinder 231 for driving the rear wheels to rotate, and a rear angle detection sensor 221 for detecting the steering angle of the rear wheels. One of the two front wheels is a steering wheel, and the other front wheel is connected to the steering wheel via a steering linkage to achieve synchronous steering. The engineering vehicle also includes a second directional valve 252, which connects the two steering cylinders of the front wheels and the two rear steering cylinders of the rear wheels.

[0046] In some embodiments, the engineering vehicle further includes a second angle detection sensor 172 for detecting the angle of the steering wheel 17. The control device 24 controls the valve position switching of the first valve 261 and the second valve 262 based on the detection results of the first angle detection sensor 22 and the second angle detection sensor 172. The second angle detection sensor can detect the steering angle of the steering wheel 17; however, due to the multiple transmission devices between the steering wheel and the steering wheels, the steering angle of the steering wheel is difficult to accurately reflect the steering angle of the steering wheels. Controlling the valve position switching of the first valve 261 and the second valve 262 based on the detection results of the first angle detection sensor 22 and the second angle detection sensor 172 provides more redundant safety assurance when encountering steering obstacles.

[0047] In some embodiments, the first directional valve 251 further has a first directional valve third position that connects the oil chamber of the steering cylinder 23 to the oil tank 28, and drives the first directional valve 251 to switch to the first directional valve third position when the steering wheel 17 is not turned.

[0048] In some embodiments, in the third valve position of the first directional valve, both the first and second chambers of the directional cylinder are connected to the oil tank 28. This enables direct connection between the two oil chambers of the steering cylinder and the oil tank, allowing the steering cylinder to float.

[0049] In some aspects, a steering control method for any of the above-mentioned engineering vehicles is also disclosed, comprising: controlling the valve position switching of the first valve 261 and the second valve 262 based on the detection results of the first angle detection sensor 22 and the pressure detection sensor 21.

[0050] In some embodiments, the steering wheel 19 has a first limit steering angle for rotation in a first direction and a second limit steering angle for rotation in a second direction. The first limit steering angle and the second limit steering angle are also the maximum steering angles of the steering wheel in the two directions. When steering, if the difference between the steering angle of the steering wheel 19 in the first direction detected by the first angle detection sensor 22 and the first limit steering angle is greater than a first threshold angle, that is, the steering wheel 19 has not yet reached the first limit steering angle in the first direction, and it still needs to turn a first threshold angle to reach the first limit steering angle, the steering angle of the steering wheel 19 in the first direction remains unchanged, and the pressure of the hydraulic oil detected by the pressure sensor continues to increase after the steering angle of the steering wheel 19 in the first direction remains unchanged (remaining unchanged means constant; in reality, there may be small vibrations in the wheel or small fluctuations in the detection result due to measurement errors, in which case remaining unchanged means the detection result is within the small fluctuation range), and continues to increase within the first threshold time, it can be determined that the steering wheel has encountered obstacles such as mud and cannot continue to turn. After the steering angle remains unchanged for a certain period of time, the first valve 261 is switched to the second valve position. After the second threshold time has elapsed since the first valve 261 was switched to the second valve position, the second valve 262 is switched to the second valve position. This achieves slow pressure relief followed by full pressure relief of the steering cylinder, thus providing effective buffer protection. When turning, the first angle detection sensor 22 detects that the difference between the turning angle of the steering wheel 19 rotating in the second direction and the second limit turning angle is greater than the second threshold angle. The turning angle of the steering wheel 19 rotating in the second direction remains unchanged, and the pressure of the hydraulic oil detected by the pressure sensor continues to increase after the turning angle of the steering wheel 19 rotating in the second direction remains unchanged, and continues to increase within the third threshold time. After the third threshold time, the first valve 261 is controlled to switch to the second valve position. After the first valve 261 switches to the second valve position and a fourth threshold time has elapsed, the second valve 262 is controlled to switch to the second valve position. This part is similar to the control process of the steering wheel rotating in the first direction described above. The second threshold angle and the first threshold angle can be set to be the same or different. The first threshold time and the third threshold time can be set to be the same or different. The second threshold time and the fourth threshold time can be set to be the same or different.

[0051] In some embodiments, the steering wheel 19 has a first limit steering angle for rotation in a first direction and a second limit steering angle for rotation in a second direction. When steering, the first angle detection sensor 22 detects that the difference between the steering angle of the steering wheel 19 in the first direction and the first limit steering angle is equal to a first threshold angle, and controls the first valve 261 to switch to the second valve position. After the first angle detection sensor 22 detects that the steering angle of the steering wheel 19 in the first direction is equal to the first limit steering angle, it controls the second valve 262 to switch to the second valve position. Similarly, when steering, the first angle detection sensor 22 detects that the difference between the steering angle of the steering wheel 19 in the second direction and the second limit steering angle is equal to a second threshold angle, and controls the first valve 261 to switch to the second valve position. The first threshold angle and the second threshold angle can be set to the same value, for example, both being 1 degree, or they can be set differently. In this embodiment, when the steering wheel turns towards the maximum steering angle, the steering cylinder is depressurized at a low back pressure before reaching the maximum steering angle, and then fully depressurized after reaching the maximum steering angle. This can achieve smooth operation of the steering wheel during the turning process towards the maximum steering angle and provide effective buffer protection for the steering system.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method of steering control of a work vehicle, characterized by, The engineering vehicles include: Frame; The axle is connected to the vehicle frame; A steering wheel assembly, including a steering wheel pivotally connected to the axle via a steering knuckle relative to the axle; A first tie rod, the first end of which is hinged to the steering knuckle, is used to pull the steering knuckle to swing relative to the axle so that the steering wheel turns. The length of the first tie rod is less than the radius of the steering wheel. A rocker arm is hinged to the vehicle frame. The hinge point where the rocker arm is hinged to the vehicle frame is higher than the hinge point where the first tie rod is hinged to the steering knuckle. The rocker arm is hinged to the second end of the first tie rod. The second pull rod has its first end hinged to the rocker arm; A steering drive mechanism, mounted on the vehicle frame, includes a drive unit and a rocker arm hinged to a first end and a second end of a second tie rod. The second end of the rocker arm is connected to the drive unit, and the drive unit is used to drive the rocker arm to swing to steer the steering wheel. The steering wheel, the drive unit including a power steering system driven between the steering wheel and the rocker arm, the steering wheel assembly including a pressure detection sensor, a first angle detection sensor for detecting the steering angle of the steering wheel, and a steering cylinder for driving the steering wheel to turn, the steering cylinder having a first chamber and a second chamber, the first chamber being supplied with pressurized oil and the steering cylinder driving the steering wheel to turn in a first direction, the second chamber being supplied with pressurized oil and the steering cylinder driving the steering wheel to turn in a second direction opposite to the first direction; the power steering system including a first directional valve driven by the steering wheel, and the engineering vehicle also including a steering wheel assembly. The system includes a hydraulic system and a control device connected to the steering hydraulic system and the first angle detection sensor. The steering hydraulic system includes a hydraulic pump, a tank, a first valve and a second valve connected to the control device. The first directional valve is connected between the hydraulic pump and the steering cylinder. The first directional valve has a first directional valve position that allows hydraulic oil output from the hydraulic pump to flow into a first chamber of the steering cylinder, and a second directional valve position that allows hydraulic oil output from the hydraulic pump to flow into a second chamber of the steering cylinder. When the steering wheel is rotated in a third direction, it drives the first directional valve to switch to the first directional valve position and drives the steering assist. The power steering system drives the rocker arm to swing in the fifth direction. When the steering wheel rotates in the fourth direction, opposite to the third direction, it drives the first directional valve to switch to the second position and drives the power steering system to drive the rocker arm to swing in the sixth direction, opposite to the fifth direction. The first valve connects the oil tank to the pipeline between the hydraulic pump and the first directional valve. The second valve connects the inlet and outlet of the hydraulic pump. The first valve has a first valve position and a second valve position. In the first valve position, the first valve disconnects the pipeline between the oil tank and the hydraulic pump and the first directional valve. The second valve has a first valve position and a second valve position. In the first valve position, the second valve disconnects the connection between the inlet and outlet of the hydraulic pump. In the second valve position, the inlet and outlet of the hydraulic pump are directly connected through the second valve. The pressure detection sensor is used to detect the pressure of the hydraulic oil in the pipeline between the first valve and the first directional valve. The control device controls the valve position switching of the first valve and the second valve according to the detection results of the first angle detection sensor and the pressure detection sensor. The steering control method for the engineering vehicle includes: controlling the valve position switching of the first valve and the second valve based on the detection results of the first angle detection sensor and the pressure detection sensor; the steering wheel has a first limit steering angle for rotation in a first direction and a second limit steering angle for rotation in a second direction; during steering, if the difference between the steering angle of the steering wheel in the first direction detected by the first angle detection sensor and the first limit steering angle is greater than a first threshold angle, the steering angle of the steering wheel in the first direction remains unchanged, and the pressure of the hydraulic oil detected by the pressure detection sensor continues to increase after the steering angle of the steering wheel in the first direction remains unchanged and continues to increase within a first threshold time, then controlling the first valve to switch after the first threshold time has elapsed. The system switches the first valve to the second valve position, and after a second threshold time has elapsed since the first valve switched to the second valve position, it controls the second valve to switch to the second valve position. When turning, if the difference between the steering angle of the steering wheel rotating in the second direction detected by the first angle detection sensor and the second limit steering angle is greater than the second threshold angle, and the steering angle of the steering wheel rotating in the second direction remains unchanged, and the pressure of the hydraulic oil detected by the pressure detection sensor continues to increase after the steering angle of the steering wheel rotating in the second direction remains unchanged and continues to increase for a third threshold time, the system controls the first valve to switch to the second valve position after the third threshold time has elapsed, and controls the second valve to switch to the second valve position after a fourth threshold time has elapsed since the first valve switched to the second valve position.

2. The steering control method for engineering vehicles as described in claim 1, characterized in that, The engineering vehicle also includes a second angle detection sensor for detecting the angle of the steering wheel, and the control device controls the valve position switching of the first valve and the second valve based on the detection results of the first angle detection sensor and the second angle detection sensor.

3. The steering control method for engineering vehicles as described in claim 1, characterized in that, The first directional valve also has a third valve position that connects the oil chamber of the steering cylinder to which it is connected to the oil tank, and drives the first directional valve to switch to the third valve position when the steering wheel is not turned.

4. The steering control method for engineering vehicles as described in claim 3, characterized in that, In the third valve position of the first directional valve, both the first and second chambers of the steering cylinder are connected to the oil tank.

5. The steering control method for engineering vehicles as described in claim 1, characterized in that, The steering wheel has a first limit steering angle for rotation in a first direction and a second limit steering angle for rotation in a second direction. When steering, if the difference between the steering angle detected by the first angle detection sensor and the first limit steering angle is equal to a first threshold angle, the first valve is controlled to switch to the second valve position. After the first angle detection sensor detects that the steering angle of the steering wheel in the first direction is equal to the first limit steering angle, the second valve is controlled to switch to the second valve position. Similarly, when steering, if the difference between the steering angle detected by the first angle detection sensor and the second limit steering angle is equal to a second threshold angle, the first valve is controlled to switch to the second valve position. After the first angle detection sensor detects that the steering angle of the steering wheel in the second direction is equal to the second limit steering angle, the second valve is controlled to switch to the second valve position.

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