Steering system and engineering vehicle

Abstract

The present disclosure provides a steering system and an engineering vehicle. The steering system comprises: a steering mechanism comprising a steering bridge, a steering wheel and a steering cylinder, the steering cylinder being configured to drive the steering wheel to deflect left and right relative to the steering bridge; a steering control mechanism; a transmission mechanism configured to drive the steering wheel to deflect left and right relative to the steering bridge; a full hydraulic steering gear comprising a motor; and a steering mode switching device configured to switch the steering system between a first steering mode and a second steering mode, in the first steering mode, the steering control mechanism is in driving connection with the transmission mechanism, the transmission mechanism drives the steering wheel to deflect in response to a steering action of the steering control mechanism, in the second steering mode, the steering control mechanism is in driving connection with the motor, the motor supplies oil to the steering cylinder in response to the steering action of the steering control mechanism to drive the steering cylinder to deflect the steering wheel. The steering system and the engineering vehicle of the present disclosure can meet the steering requirements under different working conditions.

Description

Technical Field

[0001] This disclosure relates to the field of engineering vehicles, and particularly to a steering system and an engineering vehicle. Background Technology

[0002] Wheeled engineering vehicles, such as tire cranes and wheeled excavators, can use either a fully hydraulic or mechanical steering system for steering, but they also have the following problems:

[0003] When driving in harsh working environments such as unpaved roads, the mechanical steering system is unable to absorb the impact of road feedback, and the steering wheel will exert a large impact on the driver, which will greatly affect the driver's operation.

[0004] In a fully hydraulic steering system, the lack of a mechanical connection between the steering wheel and the axle results in no feedback force, leading to a lack of road feel for the driver. This can cause excessive steering wheel turning, posing a significant safety hazard at high speeds. Furthermore, during vehicle operation, hydraulic fluid leakage may occur in the fully hydraulic steering system and control valve assembly, causing unloading of the steering cylinders and resulting in uncoordinated steering or even steering failure.

[0005] The aforementioned problems make it difficult for the current steering system to meet the steering requirements under different operating conditions. Summary of the Invention

[0006] The purpose of this disclosure is to provide a steering system and engineering vehicle to meet steering requirements under different working conditions.

[0007] A first aspect of this disclosure provides a steering system, comprising:

[0008] A steering mechanism includes a steering axle, a steering wheel, and a steering cylinder, wherein the steering cylinder is drivenly connected to the steering wheel and configured to drive the steering wheel to deflect left and right relative to the steering axle;

[0009] Steering mechanism;

[0010] A transmission mechanism is connected to the steering wheel and configured to drive the steering wheel to deflect left and right relative to the steering axle;

[0011] A fully hydraulic steering system, including a motor; and

[0012] A steering mode switching device is configured to switch the steering system between a first steering mode and a second steering mode. In the first steering mode, the steering mode switching device drives the steering control mechanism to drive the transmission mechanism, and the transmission mechanism drives the steering wheel to deflect in response to the operation of the steering control mechanism. In the second steering mode, the steering mode switching device drives the steering control mechanism to drive the motor, and the motor supplies oil to the steering cylinder in response to the operation of the steering control mechanism, so that the steering cylinder drives the steering wheel to deflect.

[0013] According to some embodiments of this disclosure, the steering system includes a first hydraulic pump, in a second steering mode, the first hydraulic pump is fluidly connected to the fully hydraulic steering gear, the fully hydraulic steering gear is fluidly connected to the steering cylinder, and the first hydraulic pump supplies oil to the steering cylinder through the fully hydraulic steering gear.

[0014] According to some embodiments of this disclosure, in the first steering mode, the first hydraulic pump is fluidly connected to the steering cylinder, the first hydraulic pump is disconnected from the fully hydraulic steering gear, and the first hydraulic pump supplies oil to the steering cylinder in response to the deflection of the steering wheel.

[0015] According to some embodiments of this disclosure

[0016] The steering axle includes a front axle, the steering wheel includes a front wheel, the steering cylinder includes a front axle steering cylinder, the front axle steering cylinder is driven and connected to the front wheel drive and configured to drive the front wheel to deflect left and right relative to the front axle;

[0017] The steering system includes a reversing control valve disposed on a hydraulic line between the first hydraulic pump and the front axle steering cylinder and configured to selectively connect the outlet of the first hydraulic pump to one of the two working ports of the front axle steering cylinder, so as to change the deflection direction of the front wheels by changing the direction of movement of the piston of the front axle steering cylinder.

[0018] According to some embodiments of this disclosure, the steering system includes a steering mode control valve disposed on a hydraulic line at the outlet end of the first hydraulic pump. The steering mode control valve has a first valve position and a second valve position. In the first valve position, the first hydraulic pump is fluidly connected to the steering cylinder, and in the second valve position, the first hydraulic pump is fluidly connected to the fully hydraulic steering gear.

[0019] According to some embodiments of this disclosure, the steering axle includes a front axle and a rear axle, the steering wheels include front wheels and rear wheels, the steering cylinders include a front axle steering cylinder and a rear axle steering cylinder, the front axle steering cylinder is connected to the front wheel drive and configured to drive the front wheels to deflect left and right relative to the front axle, the rear axle steering cylinder is connected to the rear wheel drive and configured to drive the rear wheels to deflect left and right relative to the rear axle, the fully hydraulic steering gear has a first working port and a second working port, the motor responds to the actuation action of the steering mechanism, causing oil to enter one of the first working port and the second working port and return oil to the other, the steering system includes:

[0020] A front wheel deflection control valve, located on a hydraulic line between two working ports of the fully hydraulic steering gear and two working ports of the front axle steering cylinder, is configured to selectively connect the first working port of the fully hydraulic steering gear to one of the two working ports of the front axle steering cylinder, and selectively connect the second working port of the fully hydraulic steering gear to the other of the two working ports of the front axle steering cylinder, so as to change the deflection direction of the front wheels by changing the movement direction of the piston of the front axle steering cylinder; and

[0021] A rear wheel deflection control valve is located on the hydraulic line between the two working ports of the fully hydraulic steering gear and the two working ports of the rear axle steering cylinder. It is configured to selectively connect the first working port of the fully hydraulic steering gear to one of the two working ports of the rear axle steering cylinder, and selectively connect the second working port of the fully hydraulic steering gear to the other of the two working ports of the rear axle steering cylinder, so as to change the deflection direction of the rear wheel by changing the movement direction of the piston of the rear axle steering cylinder.

[0022] According to some embodiments of this disclosure

[0023] The front wheel deflection control valve has a first port, a second port, a third port, a fourth port, and a fifth port. The first and second ports of the front wheel deflection control valve are both fluidly connected to the first working port of the fully hydraulic steering gear. The third port of the front wheel deflection control valve is fluidly connected to one of the rod chamber and the rodless chamber of the front axle steering cylinder. The fourth port of the front wheel deflection control valve is fluidly connected to the other of the rod chamber and the rodless chamber of the front axle steering cylinder.

[0024] The front wheel deflection control valve has a first valve position and a second valve position. In the first valve position, the first oil port of the front wheel deflection control valve is connected to the fifth oil port of the front wheel deflection control valve. In the second valve position, the second oil port of the front wheel deflection control valve is connected to the third oil port of the front wheel deflection control valve, and the fourth oil port of the front wheel deflection control valve is connected to the fifth oil port of the front wheel deflection control valve.

[0025] The rear wheel deflection control valve has a first port, a second port, a third port, a fourth port, and a fifth port. The first and second ports of the rear wheel deflection control valve are both fluidly connected to the second working port of the fully hydraulic steering gear. The third port of the rear wheel deflection control valve is fluidly connected to one of the rod chamber and the rodless chamber of the rear axle steering cylinder. The fourth port of the rear wheel deflection control valve is fluidly connected to the other of the rod chamber and the rodless chamber of the rear axle steering cylinder. The fifth port of the rear wheel deflection control valve is fluidly connected to the fifth port.

[0026] The rear wheel deflection control valve has a first valve position, a second valve position, and a third valve position. In the first valve position, the second port of the rear wheel deflection control valve is connected to the third port, and the fourth port is connected to the fifth port. In the second valve position, the first port is connected to the fifth port. In the third valve position, the second port is connected to the fourth port, and the third port is connected to the fifth port.

[0027] According to some embodiments of this disclosure, the second steering mode includes a first sub-mode, a second sub-mode, and a third sub-mode.

[0028] In the first sub-mode, the front wheel deflection control valve is in the second valve position, and the rear wheel deflection control valve is in the first valve position;

[0029] In the second sub-mode, the front wheel deflection control valve is in the second valve position, and the rear wheel deflection control valve is in the third valve position;

[0030] In the third sub-mode, the front wheel deflection control valve is in the first valve position, and the rear wheel deflection control valve is in the third valve position.

[0031] According to some embodiments of this disclosure, the steering system includes:

[0032] Second hydraulic pump; and

[0033] An emergency control valve, located on the hydraulic line at the outlet end of the second hydraulic pump, is configured to, in the first steering mode, when the output pressure of the first hydraulic pump is less than a preset pressure, fluidly connect the second hydraulic pump to the steering cylinder so that the second hydraulic pump can supply oil to the steering cylinder.

[0034] According to some embodiments of this disclosure, the emergency control valve has a first valve position and a second valve position. The control terminal of the emergency control valve is configured to switch the emergency control valve from the first valve position to the second valve position when the output pressure of the first hydraulic pump is less than a preset pressure. In the first valve position of the emergency control valve, the second hydraulic pump is fluidly connected to the return oil line. In the second valve position of the emergency control valve, the second hydraulic pump is fluidly connected to the steering cylinder and supplies oil to the steering cylinder.

[0035] According to some embodiments of this disclosure

[0036] The fully hydraulic steering gear has a first working port and a second working port. The motor responds to the operation of the steering mechanism by causing oil to enter one of the first working port and the second working port while oil returns to the other.

[0037] The steering axle includes a front axle and a rear axle, the steering wheel includes a front wheel and a rear wheel, the steering cylinder includes a front axle steering cylinder and a rear axle steering cylinder, the front axle steering cylinder is connected to the front wheel drive and is configured to drive the front wheel to deflect left and right relative to the front axle;

[0038] The steering system includes a first lock-up valve, which comprises a first hydraulically controlled check valve and a second hydraulically controlled check valve. The inlet of the first hydraulically controlled check valve and the control port of the second hydraulically controlled check valve are fluidly connected to the first hydraulic pump. The inlet of the second hydraulically controlled check valve and the control port of the first hydraulically controlled check valve are fluidly connected to the return oil line. The outlet of the first hydraulically controlled check valve is fluidly connected to the hydraulic line between one of the rod-side and rodless-side chambers of the front axle steering cylinder and the first working oil port. The outlet of the second hydraulically controlled check valve is fluidly connected to the hydraulic line between the other of the rod-side and rodless-side chambers of the front axle steering cylinder and the second working oil port.

[0039] According to some embodiments of this disclosure

[0040] The fully hydraulic steering gear has a first working port and a second working port. The motor responds to the operation of the steering mechanism by causing oil to enter one of the first working port and the second working port while oil returns to the other.

[0041] In the first steering mode, the first hydraulic pump is fluidly connected to the steering cylinder, the first hydraulic pump is disconnected from the fully hydraulic steering gear, and the first hydraulic pump supplies oil to the steering cylinder in response to the deflection of the steering wheel;

[0042] The steering axle includes a front axle and a rear axle, the steering wheel includes a front wheel and a rear wheel, the steering cylinder includes a front axle steering cylinder and a rear axle steering cylinder, the front axle steering cylinder is connected to the front wheel drive and is configured to drive the front wheel to deflect left and right relative to the front axle;

[0043] The steering system includes a second lock-up valve, which includes a third hydraulic check valve and a fourth hydraulic check valve. One of the first and second working ports is fluidly connected to the inlet of the third hydraulic check valve and the control port of the fourth hydraulic check valve. The other of the first and second working ports is fluidly connected to the inlet of the fourth hydraulic check valve and the control port of the third hydraulic check valve. The outlet of the third hydraulic check valve is fluidly connected to one of the rod-side and rodless-side chambers of the rear axle steering cylinder. The outlet of the fourth hydraulic check valve is fluidly connected to the other of the rod-side and rodless-side chambers of the rear axle steering cylinder.

[0044] According to some embodiments of this disclosure, the steering system includes a flow regulating valve disposed on a hydraulic line at the outlet end of a first hydraulic pump and configured to regulate the flow rate of the steering cylinder.

[0045] According to some embodiments of this disclosure

[0046] The steering mode switching device includes:

[0047] The input shaft is connected to the steering mechanism via a transmission.

[0048] The first output shaft is connected to the transmission mechanism; and

[0049] The second output shaft is connected to the motor drive.

[0050] In the first steering mode, the input shaft is driven to the first output shaft, so that the steering control mechanism is driven to the transmission mechanism; in the second steering mode, the input shaft is driven to the second output shaft, so that the steering control mechanism is driven to the motor.

[0051] According to some embodiments of this disclosure

[0052] The steering mode switching device includes:

[0053] An input gear is mounted on the input shaft and can rotate with the input shaft;

[0054] A first output gear is mounted on a first output shaft and meshes with the input gear; and

[0055] The second output gear is mounted on the second output shaft and meshes with the input gear;

[0056] In the first steering mode, the first output gear is fixed to the first output shaft so that the first output shaft can rotate synchronously with the first output gear, and the second output shaft is rotatably arranged relative to the second output gear. In the second steering mode, the second output gear is fixed to the second output shaft so that the second output shaft can rotate synchronously with the second output gear, and the second output shaft is rotatably arranged relative to the second output gear.

[0057] According to some embodiments of this disclosure, the steering mode switching device includes:

[0058] A first limiting component is movably mounted on the first output shaft. Along the direction of movement of the first limiting component, the first limiting component has a first position and a second position. In the first position, the first limiting component engages with the first output shaft and the first output gear to restrict rotation of the first output shaft relative to the first output gear. In the second position, the first limiting component disengages from the first output gear, allowing the first output shaft to rotate relative to the first output gear.

[0059] The second limiting component is movably mounted on the second output shaft. Along the movement direction of the second limiting component, the second limiting component has a first position and a second position. In the first position, the second limiting component is engaged with the second output shaft and the second output gear to restrict the rotation of the second output shaft relative to the second output gear. In the second position, the second limiting component is disengaged from the second output gear, and the second output shaft can rotate relative to the second output gear.

[0060] According to some embodiments of this disclosure

[0061] The first limiting component is splined to the first output shaft, and / or the second limiting component is splined to the second output shaft; and / or

[0062] The first limiting component is provided with a first external tooth, the first output gear is provided with a first internal tooth adapted to the first external tooth, and / or the second limiting component is provided with a second external tooth, and the second output gear is provided with a second internal tooth adapted to the second external tooth.

[0063] According to some embodiments of this disclosure

[0064] The axis of the first output shaft is set parallel to the axis of the second output shaft, and the first limiting component and the second limiting component are movably set along the axial direction of the first output shaft;

[0065] The steering mode switching device includes a switching component, which is drivenly connected to the first limiting component and the second limiting component and configured to drive the first limiting component and the second limiting component to move synchronously along the axial direction of the first output shaft, wherein, when one of the first limiting component and the second limiting component is in a first position, the other of the first limiting component and the second limiting component is in a second position.

[0066] According to some embodiments of this disclosure, the steering mode switching device includes a drive device that is driven connected to the switching component and configured to drive the switching component to move axially along the first output shaft.

[0067] A second aspect of this disclosure provides an engineering vehicle including the steering system described in the first aspect of this disclosure.

[0068] In the steering system provided in this disclosure, the steering mode switching device enables the steering system to switch between a first steering mode and a second steering mode. In the first steering mode, based on the steering control mechanism, transmission mechanism, and steering mechanism, the steering system can achieve mechanical steering, allowing the driver to obtain road feel, thereby better understanding road conditions, improving the stability of steering control, and reducing safety risks at high speeds. This can meet the steering requirements of engineering vehicles under high-speed driving conditions. In the second steering mode, based on the steering control mechanism, fully hydraulic steering gear, and steering mechanism, the steering system can achieve fully hydraulic steering, reducing the impact of road feedback shock on driver operation, reducing driver discomfort, and meeting the steering requirements of engineering vehicles to reduce impact under low-speed or harsh environmental driving conditions.

[0069] The engineering vehicle provided in this disclosure has the advantages of the aforementioned steering system.

[0070] Other features and advantages of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0071] The accompanying drawings, which are included to provide a further understanding of this disclosure and form part of this application, illustrate exemplary embodiments of this disclosure and are used to explain this disclosure, but do not constitute an undue limitation of this disclosure. In the drawings:

[0072] Figure 1 This is a schematic diagram of the steering system according to some embodiments of the present disclosure.

[0073] Figure 2 This is a schematic diagram of the hydraulic principle of a steering system according to some embodiments of the present disclosure.

[0074] Figure 3 This is a schematic diagram of the structure of a steering mode switching device according to some embodiments of the present disclosure.

[0075] Figures 1 to 3 In the figures, the labels represent:

[0076] 1. Steering control mechanism; 11. Steering wheel; 12. Steering column;

[0077] 2. Steering mode switching device; 21. Input shaft; 22. Input gear; 23a. First output shaft; 230a. First spline; 23b. Second output shaft; 230b. Second spline; 24a. First output gear; 24b. Second output gear; 25a. First bearing; 25b. Second bearing; 26a. First limiting component; 26b. Second limiting component; 27. Switching component; 28. Support shaft; 29. ​​Drive device;

[0078] 31. Fully hydraulic steering gear; 311. Motor; 312. Distribution valve; 321. First hydraulic pump; 322. Second hydraulic pump; 33. Steering mode control valve; L. First working port; R. Second working port; 341. Front wheel yaw control valve; A1. First port of the front wheel yaw control valve; B1. Second port of the front wheel yaw control valve; C1. Third port of the front wheel yaw control valve; D1. Fourth port of the front wheel yaw control valve; E1. Fifth port of the front wheel yaw control valve; 342. Rear wheel yaw control valve; A 2. First port of the rear wheel deflection control valve; B2. Second port of the rear wheel deflection control valve; C2. Third port of the rear wheel deflection control valve; D2. Fourth port of the rear wheel deflection control valve; E2. Fifth port of the rear wheel deflection control valve; 343. Reversing control valve; 35. Emergency control valve; 361. First lock-up valve; 3611. First hydraulically piloted check valve; 3612. Second hydraulically piloted check valve; 362. Second lock-up valve; 3621. Third hydraulically piloted check valve; 3622. Fourth hydraulically piloted check valve; 37. Flow regulating valve;

[0079] 4. Front axle steering mechanism; 41. Front axle steering cylinder; 41a. First front axle steering cylinder; 41b. Second front axle steering cylinder; 42. Front axle; 43. Front wheel; 43a. First front wheel; 43b. Second front wheel;

[0080] 5. Rear axle steering mechanism; 51. Rear axle steering cylinder; 51a. First rear axle steering cylinder; 51b. Second rear axle steering cylinder; 52. Rear axle; 53. Rear wheel; 53a. First rear wheel; 53b. Second rear wheel;

[0081] 6. Transmission mechanism; 611. First drive shaft; 612. First angle transmission; 613. Second drive shaft; 614. Second angle transmission; 615. Third drive shaft; 616. Third angle transmission; 621. Fourth angle transmission; 622. Fourth drive shaft; 623. Fifth angle transmission; 624. Fifth drive shaft; 625. Sixth angle transmission; 626. Steering arm; 627. Steering tie rod; 628. Steering knuckle arm;

[0082] 7. Central rotating body. Detailed Implementation

[0083] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0084] 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 this disclosure. 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 drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0085] In the description of this disclosure, 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 disclosure.

[0086] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this disclosure; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0087] refer to Figures 1 to 3 Some embodiments of this disclosure provide a steering system including a steering mechanism, a steering control mechanism 1, a transmission mechanism 6, a fully hydraulic steering gear 31, and a steering mode switching device 2.

[0088] The steering mechanism includes a steering axle, steering wheels, and a steering cylinder. The steering cylinder is drivenly connected to the steering wheels and configured to drive the steering wheels to deflect left and right relative to the steering axle. A transmission mechanism 6 is drivenly connected to the steering wheels and configured to drive the steering wheels to deflect left and right relative to the steering axle. The fully hydraulic steering gear 31 includes a motor 311. A steering mode switching device 2 is configured to switch the steering system between a first steering mode and a second steering mode. In the first steering mode, the steering mode switching device 2 drives the steering operating mechanism 1 to the transmission mechanism 6, and the transmission mechanism 6 drives the steering wheels to deflect in response to the operating action of the steering operating mechanism 1. In the second steering mode, the steering mode switching device 2 drives the steering operating mechanism 1 to the motor 311, and the motor 311 supplies hydraulic fluid to the steering cylinder in response to the operating action of the steering operating mechanism 1, causing the steering cylinder to drive the steering wheels to deflect.

[0089] Optionally, the steering mechanism includes a front axle steering mechanism 4 and a rear axle steering mechanism 5. The front axle steering mechanism 4 includes a front axle 42, front wheels 43, and a front axle steering cylinder 41. The front axle steering cylinder 41 is drivenly connected to the front wheels 43 and configured to drive the front wheels 43 to deflect left and right relative to the front axle 42. The rear axle steering mechanism 5 includes a rear axle 52, rear wheels 53, and a rear axle steering cylinder 51. The rear axle steering cylinder 51 is drivenly connected to the rear wheels 53 and configured to drive the rear wheels 53 to deflect left and right relative to the rear axle 52.

[0090] Optionally, refer to Figure 1 and Figure 2The front wheels 43 include a first front wheel 43a and a second front wheel 43b respectively disposed on the left and right sides of the front axle 42. The front axle steering cylinder 41 includes a first front axle steering cylinder 41a and a second front axle steering cylinder 41b respectively disposed corresponding to the first front wheel 43a and the second front wheel 43b. The rear wheels 53 include a first rear wheel 53a and a second rear wheel 53b respectively disposed on the left and right sides of the rear axle 52. The rear axle steering cylinder 51 includes a first rear axle steering cylinder 51a and a second rear axle steering cylinder 51b respectively disposed corresponding to the first rear wheel 53a and the second rear wheel 53b. The front axle steering cylinder 41 and the rear axle steering cylinder 51 are used to transmit steering force to the corresponding steering wheels during steering and also play a buffering role.

[0091] Optionally, the steering control mechanism 1 includes a steering wheel and a steering column assembly that is driven to the steering wheel.

[0092] The driver transmits angle and torque to the steering axle through the steering control mechanism 1 to control the vehicle's steering. In the first steering mode, road surface stimuli can be fed back to the driver through the steering control mechanism 1, allowing the driver to understand the road conditions.

[0093] According to the rotation angle of the steering wheel, the hydraulic oil of the fully hydraulic steering system 31 enters the motor 311 through the distribution valve 312, which drives the rotor of the motor 311 to rotate with the steering wheel, and injects the hydraulic oil into the steering cylinder in a directional and quantitative manner.

[0094] Optionally, the transmission mechanism 6 includes a first drive shaft 611, a first angle actuator 612, a second drive shaft 613, a second angle actuator 614, a third drive shaft 615, and a third angle actuator 616, which are disposed on the upper structure and connected in sequence. Optionally, the transmission mechanism 6 includes a fourth angle actuator 621, a fourth drive shaft 622, a fifth angle actuator 623, a fifth drive shaft 624, a sixth angle actuator 625, a steering drop arm 626, a steering tie rod 627, and a steering knuckle arm 628, which are disposed on the lower structure and connected in sequence.

[0095] The first drive shaft 611, the second drive shaft 613, the third drive shaft 615, the fourth drive shaft 622, and the fifth drive shaft 624 are used to transmit the angle and torque generated by the rotation of the steering wheel. The first angle actuator 612, the second angle actuator 614, the third angle actuator 616, the fourth angle actuator 621, the fifth angle actuator 623, and the sixth angle actuator 625 are used to change the torque and angle generated by the rotation of the steering wheel.

[0096] Optionally, the steering system includes a center rotary body 7. The center rotary body 7 is used to optionally connect the steering mechanism located in the upper structure and the lower structure, so that the torque and angle generated by the rotation of the steering wheel can be transmitted to the steering wheels through the rotation of the center rotary body 7.

[0097] Optionally, one end of the steering drop arm 626 is connected to the sixth angle actuator 625, and the other end is connected to the steering tie rod 627. The steering tie rod 627 is used to convert the swing of the steering drop arm 626 into the rotation of the steering knuckle arm 628. The steering knuckle arm 628 is used to drive the steering wheel to rotate around the steering axle.

[0098] In the first steering mode, the steering wheel and the steering wheels are mechanically connected through various drive shafts, angle transmissions, steering arm 626, steering tie rod 627, steering knuckle arm 628, etc. When the driver rotates the steering wheel, the steering angle and torque input by the steering control mechanism 1 are transmitted to the steering tie rod 627 and steering knuckle arm 628 through various drive shafts, angle transmissions, the central shaft of the central rotating body 7, etc., thereby driving the steering wheels to turn.

[0099] In the second steering mode, when the driver rotates the steering wheel, the full hydraulic steering system 31 operates under the input torque, causing hydraulic oil to enter the steering cylinder, thereby driving the steering wheels to turn.

[0100] In the second steering mode, the central slewing body 7 can cut off the power transmission between the steering control mechanism 1 and the steering tie rod 627. During slewing operations, the cab of the engineering vehicle can rotate synchronously with the working device, thus preventing the steering wheel from turning, reducing driver discomfort, and improving the reliability of the steering system.

[0101] In the steering system provided by the embodiments of this disclosure, the steering mode switching device enables the steering system to switch between a first steering mode and a second steering mode. In the first steering mode, based on the steering control mechanism, transmission mechanism, and steering mechanism, the steering system can achieve mechanical steering, allowing the driver to obtain road feel, thereby better understanding road conditions, improving the stability of steering control, and reducing safety risks at high speeds. This can meet the steering requirements of engineering vehicles under high-speed driving conditions. In the second steering mode, based on the steering control mechanism, fully hydraulic steering gear, and steering mechanism, the steering system can achieve fully hydraulic steering, reducing the impact of road feedback impact on driver operation, reducing driver discomfort, and meeting the steering requirements of engineering vehicles to reduce impact under low-speed or harsh environmental driving conditions.

[0102] The following is combined with Figure 2 The hydraulic principle of the steering system in the embodiments of this disclosure is further explained.

[0103] In some embodiments, the steering system includes a first hydraulic pump 321. In a second steering mode, the first hydraulic pump 321 is fluidly connected to a fully hydraulic steering gear 31, which is fluidly connected to a steering cylinder. The first hydraulic pump 321 supplies oil to the steering cylinder through the fully hydraulic steering gear 31.

[0104] Optionally, the first hydraulic pump 321 is mounted on and driven by the engine of the engineering vehicle. Under normal circumstances, the steering system provides the power required for steering through the first hydraulic pump 321.

[0105] In some embodiments, in a first steering mode, a first hydraulic pump 321 is fluidly connected to a steering cylinder, disconnected from a fully hydraulic steering gear 31, and supplies oil to the steering cylinder in response to the deflection of the steering wheel.

[0106] In the steering system of the above embodiment, in the first steering mode, the first hydraulic pump 321 can directly supply oil to the steering cylinder according to the deflection of the steering wheel. When the steering force is transmitted to the steering tie rod and the steering wheel turns, the first hydraulic pump can supply oil to the steering cylinder to generate an auxiliary force to drive the steering tie rod to assist the steering wheel in turning, thereby realizing hydraulic power-assisted mechanical steering, which helps to improve the operability and ease of use of the steering system.

[0107] In some embodiments, the steering axle includes a front axle 42, the steering wheels include front wheels 43, and the steering cylinder includes a front axle steering cylinder 41. The front axle steering cylinder 41 is drivenly connected to the front wheels 43 and configured to drive the front wheels 43 to deflect left and right relative to the front axle 42. The steering system includes a reversing control valve 343, which is disposed on a hydraulic line between a first hydraulic pump 321 and the front axle steering cylinder 41 and configured to selectively connect the outlet of the first hydraulic pump 321 to one of two working ports of the front axle steering cylinder 41 to change the deflection direction of the front wheels 43 by changing the direction of movement of the piston of the front axle steering cylinder 41.

[0108] Optionally, refer to Figure 2 The reversing control valve 343 is a solenoid valve, such as a three-position four-way solenoid valve with the reset state in the neutral position. In the first steering mode, the valve position of the reversing control valve 343 can switch with the direction of steering wheel rotation; for example, it can switch to the neutral position when the steering wheel is turned left. Figure 2 The valve position located on the lower side switches to the center position when the steering wheel is turned right. Figure 2 The valve is located on the upper side, thereby controlling the direction of vehicle steering by controlling the movement direction of the piston of the front axle steering cylinder 41.

[0109] In some embodiments, the steering system includes a steering mode control valve 33, which is disposed on a hydraulic line at the outlet of a first hydraulic pump 321. The steering mode control valve 33 has a first valve position and a second valve position. In the first valve position, the first hydraulic pump 321 is fluidly connected to a steering cylinder. In the second valve position, the first hydraulic pump 321 is fluidly connected to a fully hydraulic steering gear 31.

[0110] Optionally, refer to Figure 2The steering mode control valve 33 is a solenoid valve, such as a two-position two-way solenoid valve. The steering mode control valve 33 is used to switch valve positions according to the steering mode required for driving or operation, thereby controlling whether hydraulic oil passes through the fully hydraulic steering gear 31. In the first valve position of the steering mode control valve 33 (i.e....) Figure 2 In the right-hand valve position, the first hydraulic pump 321 directly supplies oil to the steering cylinder. The hydraulic circuit between the first hydraulic pump 321 and the fully hydraulic steering gear 31 is blocked, and the steering system is in the first steering mode. In the second valve position of the steering mode control valve 33 (i.e., the valve is in the right-hand valve position), the first hydraulic pump 321 directly supplies oil to the steering cylinder. The hydraulic circuit between the first hydraulic pump 321 and the fully hydraulic steering gear 31 is blocked, and the steering system is in the first steering mode. Figure 2 (The valve is located on the left side). The first hydraulic pump 321 supplies oil to the steering cylinder through the full hydraulic steering gear 31, and the steering system is in the second steering mode.

[0111] In some embodiments, the steering axle includes a front axle 42 and a rear axle 52, the steering wheels include a front wheel 43 and a rear wheel 53, and the steering cylinders include a front axle steering cylinder 41 and a rear axle steering cylinder 51. The front axle steering cylinder 41 is drivenly connected to the front wheel 43 and configured to drive the front wheel 43 to deflect left and right relative to the front axle 42. The rear axle steering cylinder 51 is drivenly connected to the rear wheel 53 and configured to drive the rear wheel 53 to deflect left and right relative to the rear axle 52. The fully hydraulic steering gear 31 has a first working port L and a second working port R. The motor 311 responds to the actuation action of the steering control mechanism 1, causing one of the first working port L and the second working port R to receive oil while the other returns oil. The steering system includes a front wheel deflection control valve 341 and a rear wheel deflection control valve 342.

[0112] The front wheel deflection control valve 341 is located on the hydraulic line between the two working ports of the fully hydraulic steering gear 31 and the two working ports of the front axle steering cylinder 41. It is configured to selectively connect the first working port L of the fully hydraulic steering gear 31 to one of the two working ports of the front axle steering cylinder 41, and selectively connect the second working port R of the fully hydraulic steering gear 31 to the other of the two working ports of the front axle steering cylinder 41, so as to change the deflection direction of the front wheel 43 by changing the movement direction of the piston of the front axle steering cylinder 41.

[0113] The rear wheel deflection control valve 342 is located on the hydraulic line between the two working ports of the fully hydraulic steering gear 31 and the two working ports of the rear axle steering cylinder 51. It is configured to selectively connect the first working port L of the fully hydraulic steering gear 31 to one of the two working ports of the rear axle steering cylinder 51, and selectively connect the second working port R of the fully hydraulic steering gear 31 to the other of the two working ports of the rear axle steering cylinder 51, so as to change the deflection direction of the rear wheel 53 by changing the movement direction of the piston of the rear axle steering cylinder 51.

[0114] In the steering system of the above embodiment, the front wheel deflection control valve 341 and the rear wheel deflection control valve 342 are used to control the oil intake or output of different working chambers of the front axle steering cylinder 41 and the rear axle steering cylinder 51, respectively, thereby controlling the deflection direction of the front wheel 43 and the rear wheel 53 by controlling the movement direction of the piston. Under the action of the front wheel deflection control valve 341 and the rear wheel deflection control valve 342, the front wheel 43 and the rear wheel 53 can deflect or not deflect, and the deflection directions of the front wheel 43 and the rear wheel 53 can be the same or different. Thus, the second steering mode of the fully hydraulic steering can be further divided into multiple sub-modes to meet the steering requirements under various terrains.

[0115] In some embodiments, the front wheel deflection control valve 341 has a first port A1, a second port B1, a third port C1, a fourth port D1, and a fifth port E1. The first port A1 and the second port B1 of the front wheel deflection control valve 341 are both fluidly connected to the first working port L of the fully hydraulic steering gear 31. The third port C1 of the front wheel deflection control valve 341 is fluidly connected to one of the rod chamber and the rodless chamber of the front axle steering cylinder 41. The fourth port D1 of the front wheel deflection control valve 341 is fluidly connected to the other of the rod chamber and the rodless chamber of the front axle steering cylinder 41.

[0116] The front wheel deflection control valve 341 has a first valve position and a second valve position. In the first valve position, the first port A1 of the front wheel deflection control valve 341 is connected to the fifth port E1 of the front wheel deflection control valve 341. In the second valve position, the second port B1 of the front wheel deflection control valve 341 is connected to the third port C1 of the front wheel deflection control valve 341, and the fourth port D1 of the front wheel deflection control valve 341 is connected to the fifth port E1 of the front wheel deflection control valve 341.

[0117] The rear wheel deflection control valve 342 has a first port A2, a second port B2, a third port C2, a fourth port D2, and a fifth port E2. The first port A2 and the second port B2 of the rear wheel deflection control valve 342 are both fluidly connected to the second working port R of the fully hydraulic steering gear 31. The third port C2 of the rear wheel deflection control valve 342 is fluidly connected to one of the rod chamber and the rodless chamber of the rear axle steering cylinder 51. The fourth port D2 of the rear wheel deflection control valve 342 is fluidly connected to the other of the rod chamber and the rodless chamber of the rear axle steering cylinder 51. The fifth port E2 of the rear wheel deflection control valve 342 is fluidly connected to the fifth port E1 of the rear axle steering cylinder 51.

[0118] The rear wheel deflection control valve 342 has a first valve position, a second valve position, and a third valve position. In the first valve position, the second port B2 of the rear wheel deflection control valve 342 is connected to the third port C2, and the fourth port D2 is connected to the fifth port E2. In the second valve position, the first port A2 of the rear wheel deflection control valve 342 is connected to the fifth port E2. In the third valve position, the second port B2 of the rear wheel deflection control valve 342 is connected to the fourth port D2, and the third port C2 is connected to the fifth port E2.

[0119] Optionally, the front wheel deflection control valve 341 has a third valve position. In the third valve position, the second port B1 of the front wheel deflection control valve 341 is connected to the fourth port D1 of the front wheel deflection control valve 341, and the third port C1 of the front wheel deflection control valve 341 is connected to the fifth port E1 of the front wheel deflection control valve 341.

[0120] Optionally, the front wheel deflection control valve 341 and the rear wheel deflection control valve 342 are integrated into one Figure 2 The multi-way directional valve shown has both ports in the reset state. Figure 2 The shown position is the middle position, which is the second valve position.

[0121] In some embodiments, the second steering mode includes a first sub-mode, a second sub-mode, and a third sub-mode. In the first sub-mode, the front wheel deflection control valve 341 is in the second valve position, and the rear wheel deflection control valve 342 is in the first valve position. In the second sub-mode, the front wheel deflection control valve 341 is in the second valve position, and the rear wheel deflection control valve 342 is in the third valve position. In the third sub-mode, the front wheel deflection control valve 341 is in the first valve position, and the rear wheel deflection control valve 342 is in the third valve position.

[0122] The working principle of the steering system under different sub-modes of the first steering mode and the second steering mode will be further explained below based on the front wheel deflection control valve 341 and the rear wheel deflection control valve 342 of the above embodiments.

[0123] In the first steering mode, the steering mode control valve 33 is in the first valve position. Figure 2 The valve position located on the right side is for hydraulic power steering. Both the front wheel yaw control valve 341 and the rear wheel yaw control valve 342 are in the second valve position. Figure 2 (The valve is located in the middle position). Hydraulic oil from the first hydraulic pump 321 flows to the reversing control valve 343.

[0124] When the steering wheel is turned to the left, the reversing control valve 343 switches to... Figure 2 The valve position is located on the lower side. Hydraulic oil enters the rodless chamber of the first front wheel steering cylinder 41a and the rod chamber of the second front wheel steering cylinder 41b through the front wheel deflection control valve 341, causing the first front wheel 43a and the second front wheel 43b to deflect to the left together.

[0125] When the steering wheel is turned to the right, the reversing control valve 343 switches to... Figure 2 The valve is located on the upper side. Hydraulic oil enters the rod chamber of the first front wheel steering cylinder 41a and the rodless chamber of the second front wheel steering cylinder 41b through the front wheel deflection control valve 341, causing the first front wheel 43a and the second front wheel 43b to deflect to the right together.

[0126] In the first steering mode, the steering system can achieve two-wheel steering with the front wheels deflecting.

[0127] In the first sub-mode of the second steering mode, the steering mode control valve 33 is in the second valve position. Figure 2 The valve position on the left side indicates full hydraulic steering. The front wheel yaw control valve 341 is in the second valve position (…). Figure 2 The valve is in the middle position, and the rear wheel deflection control valve 342 is in the first position. Figure 2 (The valve is located on the left side), and hydraulic oil from the first hydraulic pump 321 flows to the fully hydraulic steering gear 31.

[0128] When the steering wheel 11 turns left, hydraulic oil enters the front wheel deflection control valve 341 through the first working port L of the full hydraulic steering gear 31 and the central rotating body 7. This oil then enters the rodless chamber of the first front wheel steering cylinder 41a and the rod chamber of the second front wheel steering cylinder 41b, causing the first front wheels 43a and 43b to deflect to the left together. The hydraulic oil discharged from the first front wheel steering cylinders 41a and 41b passes sequentially through the front wheel deflection control valve 341 and the rear wheel deflection control valve 342 before entering the rod chamber of the first rear wheel steering cylinder 51a and the rodless chamber of the second rear wheel steering cylinder 51b, causing the first rear wheels 53a and 53b to deflect to the left together, meaning both front and rear wheels turn left simultaneously.

[0129] When the steering wheel 11 turns right, hydraulic oil enters the rear wheel deflection control valve 342 through the second working port R of the full hydraulic steering gear 31 and the central rotating body 7. This oil then enters the rodless chamber of the first rear wheel steering cylinder 51a and the rod chamber of the second rear wheel steering cylinder 51b, causing the first rear wheel 53a and the second rear wheel 53b to deflect to the right together. The hydraulic oil discharged from the first rear wheel steering cylinder 51a and the second rear wheel steering cylinder 51b passes sequentially through the rear wheel deflection control valve 342 and the front wheel deflection control valve 341 before entering the rod chamber of the first front wheel steering cylinder 41a and the rodless chamber of the second front wheel steering cylinder 41b, causing the first rear wheel 53a and the second rear wheel 53b to deflect to the right together, meaning both the front and rear wheels turn right simultaneously.

[0130] In the first sub-mode of the second steering mode, the steering system can achieve crab steering.

[0131] In the second sub-mode of the second steering mode, the steering mode control valve 33 is in the second valve position. Figure 2 The valve position on the left side indicates full hydraulic steering. The front wheel yaw control valve 341 is in the second valve position (…). Figure 2 The valve is in the middle position, and the rear wheel deflection control valve 342 is in the third position. Figure 2 (The valve is located on the right side of the valve position). Hydraulic oil from the first hydraulic pump 321 flows to the fully hydraulic steering gear 31, so that the flow rate of hydraulic oil is proportional to the rotation angle of the steering wheel 11.

[0132] When the steering wheel 11 turns left, hydraulic oil enters the front wheel deflection control valve 341 through the first working port L of the full hydraulic steering gear 31 and the central rotating body 7. This oil then enters the rodless chamber of the first front wheel steering cylinder 41a and the rod chamber of the second front wheel steering cylinder 41b, causing the first front wheels 43a and 43b to deflect to the left together. The hydraulic oil discharged from the first and second front wheel steering cylinders 41a and 41b passes sequentially through the front wheel deflection control valve 341 and the rear wheel deflection control valve 342 before entering the rodless chamber of the first rear wheel steering cylinder 51a and the rod chamber of the second rear wheel steering cylinder 51b, causing the first rear wheels 53a and 53b to deflect to the right together—that is, the front wheels turn left and the rear wheels turn right.

[0133] When the steering wheel 11 turns right, hydraulic oil enters the rear wheel deflection control valve 342 through the second working port R of the full hydraulic steering gear 31 and the central rotating body 7. This oil then enters the rodless chamber of the first front wheel steering cylinder 41a and the rod chamber of the second front wheel steering cylinder 41b, causing the first front wheels 43a and 43b to deflect to the left. Hydraulic oil discharged from the rod chamber of the first front wheel steering cylinder 41a and the rodless chamber of the second front wheel steering cylinder 41b passes sequentially through the front wheel deflection control valve 341 and the rear wheel deflection control valve 342 before entering the rod chamber of the first rear wheel steering cylinder 51a and the rodless chamber of the second rear wheel steering cylinder 51b, causing the first rear wheels 53a and 53b to deflect to the right—that is, the front wheels turn left and the rear wheels turn right.

[0134] In the second sub-mode of the second steering mode, the steering system can achieve four-wheel steering, and because the front and rear wheels deflect in different directions, the turning radius is smaller compared to other steering methods.

[0135] In the third sub-mode of the second steering mode, the steering mode control valve 33 is in the second valve position. Figure 2 The valve position on the left side indicates full hydraulic steering. The front wheel yaw control valve 341 is in the first position (…). Figure 2 The valve 342 is in the third position, located on the left side of the center. Figure 2 (The valve is located on the right side of the valve position). Hydraulic oil from the first hydraulic pump 321 flows to the fully hydraulic steering gear 31, so that the flow rate of hydraulic oil is proportional to the rotation angle of the steering wheel 11.

[0136] When the steering wheel 11 turns left, the hydraulic oil passes through the first working port L of the full hydraulic steering gear 31 and enters the front wheel deflection control valve 341 and the rear wheel deflection control valve 342 in sequence through the central rotating body 7, thereby entering the rod chamber of the first rear wheel steering cylinder 51a and the rodless chamber of the second rear wheel steering cylinder 51b, driving the first rear wheel 53a and the second rear wheel 53b to deflect to the right together.

[0137] When the steering wheel 11 turns right, the hydraulic oil enters the rear wheel deflection control valve 342 through the second working port R of the full hydraulic steering gear 31 and the center rotating body 7, thereby entering the rodless chamber of the first rear wheel steering cylinder 51a and the rod chamber of the second rear wheel steering cylinder 51b, causing the first rear wheel 53a and the second rear wheel 53b to deflect to the left together.

[0138] In the third sub-mode of the second steering mode, the steering system can achieve two-wheel steering with rear wheel deflection.

[0139] Therefore, it can be seen that the steering system mentioned above can adapt to the steering needs of various terrains.

[0140] In some embodiments, the steering system includes a second hydraulic pump 322 and an emergency control valve 35. The emergency control valve 35 is disposed on the hydraulic line at the outlet end of the second hydraulic pump 322 and is configured to, in a first steering mode, when the output pressure of the first hydraulic pump 321 is less than a preset pressure, fluidly connect the second hydraulic pump 322 to the steering cylinder so that the second hydraulic pump 322 can supply oil to the steering cylinder.

[0141] The preset pressure can be set to the minimum pressure required for the steering cylinder to actuate. When the output pressure of the first hydraulic pump 321 is less than the preset pressure, it indicates that the first hydraulic pump 321 may have failed. Based on the steering system of the above embodiment, in the state of failure of the first hydraulic pump 321, the emergency control valve 35 can enable the second hydraulic pump 322 to be fluidly connected to the steering cylinder. The second hydraulic pump 322 can serve as an emergency power source for steering, reducing the risk of unloading the steering cylinder and thus reducing safety risks during steering.

[0142] In some embodiments, the emergency control valve 35 has a first valve position and a second valve position. The control terminal K of the emergency control valve 35 is configured to switch the emergency control valve 35 from the first valve position to the second valve position when the output pressure of the first hydraulic pump 321 is less than a preset pressure. In the first valve position of the emergency control valve 35, the second hydraulic pump 322 is fluidly connected to the return oil line. In the second valve position of the emergency control valve 35, the second hydraulic pump 322 is fluidly connected to the steering cylinder and supplies oil to the steering cylinder.

[0143] In some embodiments, the fully hydraulic steering gear 31 has a first working port L and a second working port R. The motor 311 responds to the operation of the steering control mechanism 1 by allowing oil to enter one of the first working port L and the second working port R while the other returns oil.

[0144] The steering axle includes a front axle 42 and a rear axle 52, the steering wheels include a front wheel 43 and a rear wheel 53, and the steering cylinders include a front axle steering cylinder 41 and a rear axle steering cylinder 51. The front axle steering cylinder 41 is driven to the front wheel 43 and is configured to drive the front wheel 43 to deflect left and right relative to the front axle 42.

[0145] The steering system includes a first lock-up valve 361, which includes a first hydraulically controlled check valve 3611 and a second hydraulically controlled check valve 3612. The inlet of the first hydraulically controlled check valve 3611 and the control port of the second hydraulically controlled check valve 3612 are fluidly connected to a first hydraulic pump 321. The inlet of the second hydraulically controlled check valve 3612 and the control port of the first hydraulically controlled check valve 3611 are fluidly connected to a return line. The outlet of the first hydraulically controlled check valve 3611 is fluidly connected to a hydraulic line between one of the rod-side and rodless sides of the front axle steering cylinder 41 and a first working port L. The outlet of the second hydraulically controlled check valve 3612 is fluidly connected to a hydraulic line between the other of the rod-side and rodless sides of the front axle steering cylinder 41 and a second working port R.

[0146] In the second steering mode, under the action of the first lock-up valve 361, hydraulic oil can be prevented from returning to the oil tank through the reversing control valve 343, so that the steering oil circuits of the first steering mode and the second steering mode do not interfere with each other.

[0147] In some embodiments, the fully hydraulic steering gear 31 has a first working port L and a second working port R. The motor 311 responds to the operation of the steering control mechanism 1 by allowing oil to enter one of the first working port L and the second working port R while the other returns oil.

[0148] In the first steering mode, the first hydraulic pump 321 is fluidly connected to the steering cylinder and disconnected from the full hydraulic steering gear 31. The first hydraulic pump 321 supplies oil to the steering cylinder in response to the deflection of the steering wheel.

[0149] The steering axle includes a front axle 42 and a rear axle 52, the steering wheels include a front wheel 43 and a rear wheel 53, and the steering cylinders include a front axle steering cylinder 41 and a rear axle steering cylinder 51. The front axle steering cylinder 41 is driven to the front wheel 43 and is configured to drive the front wheel 43 to deflect left and right relative to the front axle 42.

[0150] The steering system includes a second lock-up valve 362, which includes a third hydraulic check valve 3621 and a fourth hydraulic check valve 3622. One of the first working port L and the second working port R is fluidly connected to the inlet of the third hydraulic check valve 3621 and the control port of the fourth hydraulic check valve 3622. The other of the first working port L and the second working port R is fluidly connected to the inlet of the fourth hydraulic check valve 3622 and the control port of the third hydraulic check valve 3621. The outlet of the third hydraulic check valve 3621 is fluidly connected to one of the rod chamber and the rodless chamber of the rear axle steering cylinder 51. The outlet of the fourth hydraulic check valve 3622 is fluidly connected to the other of the rod chamber and the rodless chamber of the rear axle steering cylinder 51.

[0151] In the first steering mode, the second lock-up valve 362 can lock the rear axle steering cylinder 51 so that when the front wheel 43 is steering, the rear wheel 53 does not deflect and always maintains straight driving, thus improving the reliability of the steering system.

[0152] In some embodiments, the steering system includes a flow regulating valve 37, which is disposed on a hydraulic line at the outlet of the first hydraulic pump 321 and configured to regulate the flow of the steering cylinder.

[0153] The flow regulating valve 37 can calibrate and adjust the flow rate of the hydraulic oil pumped by the first hydraulic pump 321, thereby making the steering cylinder move more accurately and smoothly.

[0154] The following is combined with Figure 3 The structure of the steering mode switching device according to the embodiments of this disclosure is further explained.

[0155] In some embodiments, the steering mode switching device 2 includes an input shaft 21, a first output shaft 23a, and a second output shaft 23b. The input shaft 21 is drive-connected to the steering control mechanism 1. The first output shaft 23a is drive-connected to the transmission mechanism 6. The second output shaft 23b is drive-connected to the motor 311. In a first steering mode, the input shaft 21 is drive-connected to the first output shaft 23a, thereby connecting the steering control mechanism 1 to the transmission mechanism 6. In a second steering mode, the input shaft 21 is drive-connected to the second output shaft 23b, thereby connecting the steering control mechanism 1 to the motor 311.

[0156] The steering mode switching device 2 of the above embodiment enables the input shaft 21 to be selectively connected to the first output shaft 23a and the second output shaft 23b, so that power can be selectively transmitted from the steering control mechanism 1 to the transmission mechanism 6 or the full hydraulic steering gear 31, thereby realizing the switching of steering modes.

[0157] In some embodiments, the steering mode switching device 2 includes an input gear 22, a first output gear 24a, and a second output gear 24b. The input gear 22 is mounted on an input shaft 21 and can rotate with the input shaft 21. The first output gear 24a is mounted on a first output shaft 23a and meshes with the input gear 22. The second output gear 24b is mounted on a second output shaft 23b and meshes with the input gear 22. In a first steering mode, the first output gear 24a is fixed to the first output shaft 23a so that the first output shaft 23a can rotate synchronously with the first output gear 24a, and the second output shaft 23b is rotatably disposed relative to the second output gear 24b. In a second steering mode, the second output gear 24b is fixed to the second output shaft 23b so that the second output shaft 23b can rotate synchronously with the second output gear 24b, and the second output shaft 23b is rotatably disposed relative to the second output gear 24b.

[0158] The steering mode switching device 2 in the above embodiment adopts a gear transmission mechanism, which has a strong load-bearing capacity and is suitable for harsh construction environments. Optionally, the steering mode switching device 2 can be configured as a gearbox. Optionally, the input gear 22, the first output gear 24a, and the second output gear 24b are bevel gears, and the input shaft 21, the first output shaft 23a, and the second output shaft 23b are arranged in a specific configuration. Figure 3 The inverted T-shaped structure shown.

[0159] In some embodiments, the steering mode switching device 2 includes a first limiting member 26a and a second limiting member 26b. The first limiting member 26a is movably mounted on the first output shaft 23a. Along the direction of movement of the first limiting member 26a, the first limiting member 26a has a first position and a second position. In the first position, the first limiting member 26a is engaged with the first output shaft 23a and the first output gear 24a to restrict the rotation of the first output shaft 23a relative to the first output gear 24a. In the second position, the first limiting member 26a is disengaged from the first output gear 24a, and the first output shaft 23a can rotate relative to the first output gear 24a. The second limiting member 26b is movably mounted on the second output shaft 23b. Along the movement direction of the second limiting member 26b, the second limiting member 26b has a first position and a second position. In the first position, the second limiting member 26b is engaged with the second output shaft 23b and the second output gear 24b to restrict the rotation of the second output shaft 23b relative to the second output gear 24b. In the second position, the second limiting member 26b is disengaged from the second output gear 24b, and the second output shaft 23b can rotate relative to the second output gear 24b.

[0160] Optionally, the steering mode switching device 2 includes a first bearing 25a and a second bearing 25b. The inner ring of the first bearing 25a mates with the first output shaft 23a, and the outer ring of the first bearing 25a mates with the shaft hole of the first output gear 24a. The inner ring of the second bearing 25b mates with the first output shaft 23b, and the outer ring of the second bearing 25b mates with the shaft hole of the second output gear 24b.

[0161] In the steering mode switching device 2 of the above embodiment, the first output shaft 23a can rotate relative to the first output gear 24a, or rotate synchronously with the first output gear 24a under the action of the first limiting member 26a. The second output shaft 23b can rotate relative to the second output gear 24b, or rotate synchronously with the first output gear 24b under the action of the second limiting member 26b. By changing the positions of the first limiting member 26a and the second limiting member 26b, the connection state of the first output shaft 23a and the first output gear 24a, as well as the connection state of the second output shaft 23b and the second output gear 24b, can be changed, thereby realizing steering mode switching. Specifically, by placing the first limiting member 26a in the first position and the second limiting member 26b in the second position, power is transmitted from the steering control mechanism 1 to the transmission mechanism 6; by placing the first limiting member 26a in the second position and the second limiting member 26b in the first position, power is transmitted from the steering control mechanism 1 to the fully hydraulic steering gear 31.

[0162] In some embodiments, the first limiting member 26a is connected to the first output shaft 23a via a spline, and / or the second limiting member 26b is connected to the second output shaft 23b via a spline.

[0163] Optionally, refer to Figure 3 The first output shaft 23a has a first spline 230a on its circumferential surface, and a first limiting member 26a is connected to the first output shaft 23a via the first spline 230a. The second output shaft 23b has a second spline 230b on its circumferential surface, and a second limiting member 26b is connected to the second output shaft 23b via the second spline 230b. Optionally, the first limiting member 26a and the second limiting member 26b are claw-type clutches.

[0164] In some embodiments, the first limiting member 26a is provided with a first external tooth, the first output gear 24a is provided with a first internal tooth adapted to the first external tooth, and / or the second limiting member 26b is provided with a second external tooth, and the second output gear 24b is provided with a second internal tooth adapted to the second external tooth.

[0165] The above-mentioned connection method, which uses spline connection or internal and external gear connection, can limit the rotation of the two output shafts relative to the corresponding output gear. This limiting method is easy to process, and the load is relatively uniform and has a strong load-bearing capacity along the circumference of the first output shaft 23a or the second output shaft 23b.

[0166] In some embodiments, the axis of the first output shaft 23a and the axis of the second output shaft 23b are arranged parallel to each other, and the first limiting member 26a and the second limiting member 26b are movably arranged along the axial direction of the first output shaft 23a. The steering mode switching device 2 includes a switching member 27, which is drivenly connected to the first limiting member 26a and the second limiting member 26b and configured to drive the first limiting member 26a and the second limiting member 26b to move synchronously along the axial direction of the first output shaft 23a, wherein, when one of the first limiting member 26a and the second limiting member 26b is in a first position, the other of the first limiting member 26a and the second limiting member 26b is in a second position.

[0167] Optionally, the switching component 27 is a shift fork, with two fork heads at the end of the shift fork connected to the first limiting component 26a and the second limiting component 26b respectively, so that the first limiting component 26a and the second limiting component 26b can move with the movement of the shift fork.

[0168] In some embodiments, the steering mode switching device 2 includes a drive device 29, which is drivenly connected to the switching component 27 and configured to drive the switching component 27 to move axially along the first output shaft 23a.

[0169] Optionally, the drive unit 29 is a cylinder. Optionally, the first output shaft 23a and the second output shaft 23b are parallel, the steering mode switching device 2 includes a support shaft 28, the axis of the support shaft 28 is parallel to the first output shaft, the switching component 27 is mounted on the support shaft 28, and the support shaft 28 is connected to the moving part of the cylinder.

[0170] refer to Figure 3 When the shift fork moves to the left in the position shown in the figure, the first limiting component 26a remains engaged with the first output shaft 23a and the first output gear 24a, while the second limiting component 26b disengages from the second output gear 24b. The steering force is transmitted from the input shaft 21 to the first output shaft 23a, causing the steering system to switch to the first steering mode. When the shift fork moves to the right in the position shown in the figure, the first limiting component 26a disengages from the first output gear 24a, while the second limiting component 26b remains engaged with the second output shaft 23b and the second output gear 24b. The steering force is transmitted from the input shaft 21 to the second output shaft 23b, causing the steering system to switch to the second steering mode.

[0171] Some embodiments of this disclosure also provide an engineering vehicle including the aforementioned steering system. The engineering vehicle provided by the embodiments of this disclosure has the advantages of the aforementioned steering system.

[0172] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and not to limit them; although this disclosure 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 this disclosure or equivalent substitutions can be made to some technical features, all of which should be covered within the scope of the technical solutions claimed in this disclosure.

Claims

1. A steering system characterized by, Comprising: a steering mechanism including a steering bridge, a steering wheel and a steering cylinder, the steering cylinder being drivingly connected with the steering wheel and configured to drive the steering wheel to deflect left and right relative to the steering bridge; a steering control mechanism (1); a transmission mechanism (6) drivingly connected with the steering wheel and configured to drive the steering wheel to deflect left and right relative to the steering bridge; a full hydraulic steering gear (31) including a motor (311); and a steering mode switching device (2) configured to switch the steering system between a first steering mode and a second steering mode, in the first steering mode, the steering mode switching device (2) drivingly connects the steering control mechanism (1) with the transmission mechanism (6), the transmission mechanism (6) drives the steering wheel to deflect in response to a steering action of the steering control mechanism (1), in the second steering mode, the steering mode switching device (2) drivingly connects the steering control mechanism (1) with the motor (311), the motor (311) supplies oil to the steering cylinder in response to a steering action of the steering control mechanism (1) to drive the steering cylinder to deflect the steering wheel.

2. The steering system of claim 1, wherein, The steering system includes a first hydraulic pump (321), in the second steering mode, the first hydraulic pump (321) is fluidly connected with the full hydraulic steering gear (31), the full hydraulic steering gear (31) is fluidly connected with the steering cylinder, the first hydraulic pump (321) supplies oil to the steering cylinder through the full hydraulic steering gear (31).

3. The steering system of claim 2, wherein, In the first steering mode, the first hydraulic pump (321) is fluidly connected with the steering cylinder, the first hydraulic pump (321) is disconnected with the full hydraulic steering gear (31), the first hydraulic pump (321) supplies oil to the steering cylinder in response to a deflection of the steering wheel.

4. The steering system according to claim 3, wherein the steering bridge includes a front bridge (42), the steering wheel includes a front wheel (43), the steering cylinder includes a front bridge steering cylinder (41), the front bridge steering cylinder (41) is drivingly connected with the front wheel (43) and configured to drive the front wheel (43) to deflect left and right relative to the front bridge (42); the steering system includes a reversing control valve (343), the reversing control valve (343) is provided on a hydraulic pipeline between the first hydraulic pump (321) and the front bridge steering cylinder (41) and configured to selectively connect an outlet of the first hydraulic pump (321) with one of two working oil ports of the front bridge steering cylinder (41) to change a deflection direction of the front wheel (43) by changing a moving direction of a piston of the front bridge steering cylinder (41).

5. The steering system of claim 3, wherein, The steering system comprises a steering mode control valve (33) disposed on a hydraulic line at an outlet end of the first hydraulic pump (321), the steering mode control valve (33) having a first valve position and a second valve position, at the first valve position of the steering mode control valve (33), the first hydraulic pump (321) is in fluid connection with the steering cylinder, at the second valve position of the steering mode control valve (33), the first hydraulic pump (321) is in fluid connection with the full hydraulic steering gear (31).

6. The steering system of claim 2, wherein, The steering bridge comprises a front bridge (42) and a rear bridge (52), the steering wheel comprises a front wheel (43) and a rear wheel (53), the steering cylinder comprises a front bridge steering cylinder (41) and a rear bridge steering cylinder (51), the front bridge steering cylinder (41) is in driving connection with the front wheel (43) and is configured to drive the front wheel (43) to deflect left and right relative to the front bridge (42), the rear bridge steering cylinder (51) is in driving connection with the rear wheel (53) and is configured to drive the rear wheel (53) to deflect left and right relative to the rear bridge (52), the full hydraulic steering gear (31) has a first working oil port (L) and a second working oil port (R), the motor (311) is responsive to an operating action of the steering operating mechanism (1) to make one of the first working oil port (L) and the second working oil port (R) to be in oil and the other to be in return oil, the steering system comprises: a front wheel deflection control valve (341) disposed on a hydraulic line between the two working oil ports of the full hydraulic steering gear (31) and the two working oil ports of the front bridge steering cylinder (41), configured to selectively connect the first working oil port (L) of the full hydraulic steering gear (31) with one of the two working oil ports of the front bridge steering cylinder (41), and to selectively connect the second working oil port (R) of the full hydraulic steering gear (31) with the other of the two working oil ports of the front bridge steering cylinder (41), so as to change the deflection direction of the front wheel (43) by changing the moving direction of the piston of the front bridge steering cylinder (41); and a rear wheel deflection control valve (342) disposed on a hydraulic line between the two working oil ports of the full hydraulic steering gear (31) and the two working oil ports of the rear bridge steering cylinder (51), configured to selectively connect the first working oil port (L) of the full hydraulic steering gear (31) with one of the two working oil ports of the rear bridge steering cylinder (51), and to selectively connect the second working oil port (R) of the full hydraulic steering gear (31) with the other of the two working oil ports of the rear bridge steering cylinder (51), so as to change the deflection direction of the rear wheel (53) by changing the moving direction of the piston of the rear bridge steering cylinder (51).

7. The steering system according to claim 6, wherein The front wheel deflection control valve (341) has a first oil port (A1), a second oil port (B1), a third oil port (C1), a fourth oil port (D1), a fifth oil port (E1), the first oil port (A1) and the second oil port (B1) of the front wheel deflection control valve (341) are both in fluid connection with the first working oil port (L) of the full hydraulic steering gear (31), one of the rod cavity and the rodless cavity of the front axle steering oil cylinder (41) is in fluid connection with the third oil port (C1) of the front wheel deflection control valve (341), the other of the rod cavity and the rodless cavity of the front axle steering oil cylinder (41) is in fluid connection with the fourth oil port (D1) of the front wheel deflection control valve (341); The front wheel deflection control valve (341) has a first valve position and a second valve position, in the first valve position of the front wheel deflection control valve (341), the first oil port (A1) of the front wheel deflection control valve (341) is in communication with the fifth oil port (E1) of the front wheel deflection control valve (341), in the second valve position of the front wheel deflection control valve (341), the second oil port (B1) of the front wheel deflection control valve (341) is in communication with the third oil port (C1) of the front wheel deflection control valve (341), the fourth oil port (D1) of the front wheel deflection control valve (341) is in communication with the fifth oil port (E1) of the front wheel deflection control valve (341); The rear wheel deflection control valve (342) has a first oil port (A2), a second oil port (B2), a third oil port (C2), a fourth oil port (D2), a fifth oil port (E2), the first oil port (A2) and the second oil port (B2) of the rear wheel deflection control valve (342) are both in fluid connection with the second working oil port (R) of the full hydraulic steering gear (32), one of the rod cavity and the rodless cavity of the rear axle steering oil cylinder (51) is in fluid connection with the third oil port (C2) of the rear wheel deflection control valve (342), the other of the rod cavity and the rodless cavity of the rear axle steering oil cylinder (51) is in fluid connection with the fourth oil port (D2) of the rear wheel deflection control valve (342), the fifth oil port (E2) of the rear wheel deflection control valve (342) is in fluid connection with the fifth oil port (E1); The rear wheel deflection control valve (342) has a first valve position, a second valve position and a third valve position, at the first valve position of the rear wheel deflection control valve (342), the second oil port (B2) of the rear wheel deflection control valve (342) is in communication with the third oil port (C2) of the rear wheel deflection control valve (342), the fourth oil port (D2) of the rear wheel deflection control valve (342) is in communication with the fifth oil port (E2) of the rear wheel deflection control valve (342), at the second valve position of the rear wheel deflection control valve (342), the first oil port (A2) of the rear wheel deflection control valve (342) is in communication with the fifth oil port (E2) of the rear wheel deflection control valve (342), at the third valve position of the rear wheel deflection control valve (342), the second oil port (B2) of the rear wheel deflection control valve (342) is in communication with the fourth oil port (D2) of the rear wheel deflection control valve (342), the third oil port (C2) of the rear wheel deflection control valve (342) is in communication with the fifth oil port (E2) of the rear wheel deflection control valve (342).

8. The steering system of claim 7, wherein, The second steering mode includes a first sub-mode, a second sub-mode and a third sub-mode, In the first sub-mode, the front wheel deflection control valve (341) is at the second valve position, and the rear wheel deflection control valve (342) is at the first valve position; In the second sub-mode, the front wheel deflection control valve (341) is at the second valve position, and the rear wheel deflection control valve (342) is at the third valve position; In the third sub-mode, the front wheel deflection control valve (341) is at the first valve position, and the rear wheel deflection control valve (342) is at the third valve position.

9. A steering system according to any one of claims 2 to 8, characterised in that, The steering system includes: a second hydraulic pump (322); and An emergency control valve (35) is arranged on the hydraulic pipeline of the outlet end of the second hydraulic pump (322) and is configured to, in the first steering mode, in the state that the output pressure of the first hydraulic pump (321) is less than the preset pressure, make the second hydraulic pump (322) fluidly connected with the steering oil cylinder, so that the second hydraulic pump (322) can supply oil to the steering oil cylinder.

10. The steering system of claim 9, wherein, The emergency control valve (35) has a first valve position and a second valve position, the control end (K) of the emergency control valve (35) is configured to, in the state that the output pressure of the first hydraulic pump (321) is less than the preset pressure, make the emergency control valve (35) switch from the first valve position to the second valve position, in the first valve position of the emergency control valve (35), the second hydraulic pump (322) is fluidly connected with the oil return pipeline, in the second valve position of the emergency control valve (35), the second hydraulic pump (322) is fluidly connected with the steering oil cylinder, and the second hydraulic pump (322) supplies oil to the steering oil cylinder.

11. The steering system according to any one of claims 2 to 8, wherein The full hydraulic steering gear (31) has a first working oil port (L) and a second working oil port (R), and the motor (311) causes one of the first working oil port (L) and the second working oil port (R) to be filled with oil and the other to be drained in response to an operation of the steering operating mechanism (1); The steering bridge includes a front bridge (42) and a rear bridge (52), the steering wheel includes a front wheel (43) and a rear wheel (53), and the steering cylinder includes a front bridge steering cylinder (41) and a rear bridge steering cylinder (51), the front bridge steering cylinder (41) is drivingly connected with the front wheel (43) and is configured to drive the front wheel (43) to deflect left and right relative to the front bridge (42); The steering system includes a first lock valve (361), the first lock valve (361) includes a first hydraulic control check valve (3611) and a second hydraulic control check valve (3612), an oil inlet of the first hydraulic control check valve (3611) and a control port of the second hydraulic control check valve (3612) are fluidly connected with the first hydraulic pump (321), an oil inlet of the second hydraulic control check valve (3612) and a control port of the first hydraulic control check valve (3611) are fluidly connected with a drain line, an oil outlet of the first hydraulic control check valve (3611) is fluidly connected with a hydraulic line between one of a rod chamber and a rodless chamber of the front bridge steering cylinder (41) and the first working oil port (L), and an oil outlet of the second hydraulic control check valve (3612) is fluidly connected with a hydraulic line between the other of the rod chamber and the rodless chamber of the front bridge steering cylinder (41) and the second working oil port (R).

12. The steering system according to any one of claims 2 to 8, wherein The full hydraulic steering gear (31) has a first working oil port (L) and a second working oil port (R), and the motor (311) causes one of the first working oil port (L) and the second working oil port (R) to be filled with oil and the other to be drained in response to an operation of the steering operating mechanism (1); In the first steering mode, the first hydraulic pump (321) is fluidly connected with the steering cylinder, the first hydraulic pump (321) is disconnected from the full hydraulic steering gear (31), and the first hydraulic pump (321) supplies oil to the steering cylinder in response to a deflection of the steering wheel; The steering bridge includes a front bridge (42) and a rear bridge (52), the steering wheel includes a front wheel (43) and a rear wheel (53), and the steering cylinder includes a front bridge steering cylinder (41) and a rear bridge steering cylinder (51), the front bridge steering cylinder (41) is drivingly connected with the front wheel (43) and is configured to drive the front wheel (43) to deflect left and right relative to the front bridge (42); The steering system comprises a second lock valve (362), the second lock valve (362) comprising a third hydraulic control check valve (3621) and a fourth hydraulic control check valve (3622), one of the first working oil port (L) and the second working oil port (R) being in fluid connection with an oil inlet of the third hydraulic control check valve (3621) and a control port of the fourth hydraulic control check valve (3622), the other of the first working oil port (L) and the second working oil port (R) being in fluid connection with an oil inlet of the fourth hydraulic control check valve (3622) and a control port of the third hydraulic control check valve (3621), an oil outlet of the third hydraulic control check valve (3621) being in fluid connection with one of a rod cavity and a rodless cavity of the rear axle steering oil cylinder (51), and an oil outlet of the fourth hydraulic control check valve (3622) being in fluid connection with the other of the rod cavity and the rodless cavity of the rear axle steering oil cylinder (51).

13. The steering system of any one of claims 2 to 8, wherein, The steering system comprises a flow regulating valve (37) disposed on a hydraulic pipeline at an outlet end of a first hydraulic pump (321) and configured to regulate a flow of the steering oil cylinder.

14. The steering system according to claim 1, wherein The steering mode switching device (2) comprises: an input shaft (21) in driving connection with the steering operating mechanism (1); a first output shaft (23a) in driving connection with the transmission mechanism (6); and a second output shaft (23b) in driving connection with the motor (311); wherein, in the first steering mode, the input shaft (21) is in driving connection with the first output shaft (23a) to make the steering operating mechanism (1) in driving connection with the transmission mechanism (6), and in the second steering mode, the input shaft (21) is in driving connection with the second output shaft (23b) to make the steering operating mechanism (1) in driving connection with the motor (311).

15. The steering system according to claim 14, wherein The steering mode switching device (2) comprises: an input gear (22) mounted on the input shaft (21) and rotatable with the input shaft (21); a first output gear (24a) mounted on the first output shaft (23a) and in mesh with the input gear (22); and a second output gear (24b) mounted on the second output shaft (23b) and in mesh with the input gear (22); In the first steering mode, the first output gear (24a) is fixed with the first output shaft (23a) to enable the first output shaft (23a) to rotate synchronously with the first output gear (24a), and the second output shaft (23b) is rotatably arranged relative to the second output gear (24b); in the second steering mode, the second output gear (24b) is fixed with the second output shaft (23b) to enable the second output shaft (23b) to rotate synchronously with the second output gear (24b), and the second output shaft (23b) is rotatably arranged relative to the second output gear (24b).

16. The steering system of claim 15, wherein, The steering mode switching device (2) comprises: a first limiting component (26a) movably mounted on the first output shaft (23a), the first limiting component (26a) having a first position and a second position along a movement direction of the first limiting component (26a), in the first position of the first limiting component (26a), the first limiting component (26a) is engaged with the first output shaft (23a) and the first output gear (24a) to limit the rotation of the first output shaft (23a) relative to the first output gear (24a), in the second position of the first limiting component (26a), the first limiting component (26a) is disengaged from the first output gear (24a), and the first output shaft (23a) can rotate relative to the first output gear (24a); and a second limiting component (26b) movably mounted on the second output shaft (23b), the second limiting component (26b) having a first position and a second position along a movement direction of the second limiting component (26b), in the first position of the second limiting component (26b), the second limiting component (26b) is engaged with the second output shaft (23b) and the second output gear (24b) to limit the rotation of the second output shaft (23b) relative to the second output gear (24b), in the second position of the second limiting component (26b), the second limiting component (26b) is disengaged from the second output gear (24b), and the second output shaft (23b) can rotate relative to the second output gear (24b).

17. The steering system according to claim 16, wherein the first limiting component (26a) is connected with the first output shaft (23a) by means of a spline, and / or the second limiting component (26b) is connected with the second output shaft (23b) by means of a spline; and / or the first limiting component (26a) is provided with a first external tooth, the first output gear (24a) is provided with a first internal tooth adapted to the first external tooth, and / or the second limiting component (26b) is provided with a second external tooth, the second output gear (24b) is provided with a second internal tooth adapted to the second external tooth.

18. The steering system according to claim 16, wherein An axis of the first output shaft (23a) is arranged parallel to an axis of the second output shaft (23b), and the first limiting member (26a) and the second limiting member (26b) are movably arranged along an axial direction of the first output shaft (23a); The steering mode switching device (2) comprises a switching member (27) which is drivingly connected with the first limiting member (26a) and the second limiting member (26b) and is configured to drive the first limiting member (26a) and the second limiting member (26b) to move synchronously along the axial direction of the first output shaft (23a), wherein in a state that one of the first limiting member (26a) and the second limiting member (26b) is in the first position, the other of the first limiting member (26a) and the second limiting member (26b) is in the second position.

19. The steering system of claim 18, wherein, The steering mode switching device (2) comprises a driving device (29) which is drivingly connected with the switching member (27) and is configured to drive the switching member (27) to move along the axial direction of the first output shaft (23a).

20. An engineering vehicle characterized by: A steering system comprising the steering system according to any one of claims 1 to 19.

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