CN111688803B - Steering system and engineering machinery - Google Patents

Abstract

The present disclosure relates to a steering system, comprising: the first steering axle is a double-opposite-cylinder steering axle and comprises a first oil port and a second oil port; the second steering axle comprises a fifth oil port and a sixth oil port; the steering gear is communicated with the first oil port and the fifth oil port through the first steering oil port, is communicated with the second oil port and the sixth oil port through the second steering oil port, and is configured to control the flow direction of hydraulic oil of the first steering oil port and the second steering oil port according to a steering instruction; and the first hydraulic valve group is arranged in a flow path of the steering gear flowing to the first steering axle and the second steering axle, and is configured to selectively communicate the first steering oil port with the first oil port and/or the fifth oil port and selectively communicate the second steering oil port with the second oil port and/or the sixth oil port according to a mode selection command. The embodiment of the disclosure can improve the convenience of operation of the steering system, reduce the response time of the steering system under a control signal, and reduce the steering angle deviation of the steering system.

Description

Steering system and engineering machinery

Technical Field

The disclosure relates to the field of engineering machinery, in particular to a steering system and engineering machinery.

Background

The steering system of the engineering machinery generally adopts an electro-hydraulic proportional brake steering system: the front axle wheels are controlled by a driver through operating a steering wheel, the rotation angles of all the wheels of the rear axle output different electric signals through a program set in a controller according to the rotation angle of one wheel of the front axle and the steering mode selected by the driver, and further the opening degree of the electro-hydraulic proportional valve and the flow rate of hydraulic oil are controlled, so that the steering oil cylinder pushes all the wheels of the rear axle to rotate according to the operation intention of the driver. Wherein the rotation angle of each wheel of the front axle is detected by a sensor mounted on the axle.

Under the modes of independent steering, small-turning steering and crab steering of the front axle, when a driver operates a steering wheel, a steering device outputs hydraulic oil provided by a steering pump into a front axle oil cylinder according to the left-right rotation of the steering wheel. When the front axle wheels are steered, the front axle sensor transmits the detected steering signal to the controller. The controller calculates the required rotation angle of the rear axle and outputs corresponding control current to push an electro proportional valve for controlling the steering of the wheels of the rear axle according to the received steering signal and the current steering mode, so that the steering pump provides hydraulic oil to enter a steering oil cylinder of the rear axle through the electro proportional valve, and the rear axle is steered along with the front axle.

When the rear axle is in the independent steering mode, a driver does not operate a steering wheel, and transmits a control signal to the controller by adjusting the external control knob, and the controller automatically calculates the angle of the rear axle required to rotate according to the received signal and outputs corresponding control current to push the electro proportional valve. The steering pump provides hydraulic oil to enter the rear axle steering oil cylinder through the electro-proportional valve to start steering.

Moreover, when the front axle independent steering mode, the tight turning steering mode, the crab steering mode and the rear axle independent steering mode are switched, the front tires and the rear tires are required to be manually aligned. However, the process of manual centering is cumbersome and accuracy is difficult to ensure.

Disclosure of Invention

In view of this, the embodiments of the present disclosure provide a steering system and a construction machine, which can improve convenience of operating the steering system, reduce response time of the steering system under a control signal, and reduce deviation of a steering angle of the steering system.

In one aspect of the present disclosure, there is provided a steering system including:

the first steering axle is a double-opposite-cylinder steering axle and comprises a first oil port and a second oil port;

the second steering axle comprises a fifth oil port and a sixth oil port;

the steering gear is communicated with the first oil port and the fifth oil port through a first steering oil port, is communicated with the second oil port and the sixth oil port through a second steering oil port, and is configured to control the flow direction of hydraulic oil of the first steering oil port and the second steering oil port according to a steering instruction; and

and the first hydraulic valve group is arranged in a flow path of the steering gear flowing to the first steering axle and the second steering axle and is configured to selectively communicate the first steering oil port with the first oil port and/or the fifth oil port and selectively communicate the second steering oil port with the second oil port and/or the sixth oil port according to a mode selection command.

In some embodiments, the steering command includes a turning angle of a steering wheel, the first steer axle is configured to effect steering motions of first and second steer arms relative to a frame in accordance with the steering command, the first steer axle includes:

the first opposite oil cylinder is connected with the first steering arm through a first piston rod and is connected with the frame through a second piston rod; and

the second opposite oil cylinder is connected with the frame through a third piston rod and is connected with the second steering arm through a fourth piston rod;

the first piston rod cavity and the third piston rod rodless cavity are communicated with the first oil port, the second piston rod rodless cavity and the fourth piston rod cavity are communicated with the second oil port, the rod cavity of the second piston rod and the rodless cavity of the fourth piston rod are communicated with the third oil port, and the rodless cavity of the first piston rod and the rod cavity of the third piston rod are communicated with the fourth oil port.

In some embodiments, the steering system further comprises:

and the second hydraulic valve group is communicated with a brake oil path and is configured to selectively communicate the first oil port or the brake oil path with the third oil port and selectively communicate the second oil port or the brake oil path with the fourth oil port according to the steering instruction.

In some embodiments, the second hydraulic valve group comprises:

a first direction change valve configured to selectively communicate the first oil port or the brake oil path with the third oil port according to the steering command; and

a second directional valve configured to selectively communicate the second port or the brake oil path with the fourth port according to the steering command.

In some embodiments, the first direction valve and the second direction valve are both hydraulic control direction valves, a hydraulic control end of the first direction valve is communicated with the first oil port, and a hydraulic control end of the second direction valve is communicated with the second oil port.

In some embodiments, the second hydraulic valve group is further communicated with an oil supplementing oil path, and the second hydraulic valve group further includes:

a third direction change valve configured to communicate the oil replenishment oil passage with the first direction change valve and the second direction change valve or communicate the brake oil passage with the first direction change valve and the second direction change valve according to the steering command.

In some embodiments, the second hydraulic valve block further comprises:

the first overflow valve is arranged between the junction of the fourth oil port and the third oil port and the oil return flow path;

a first check valve configured to allow only hydraulic oil to flow unidirectionally from the fourth oil port to the first spill valve; and

a second check valve configured to allow only hydraulic oil to flow unidirectionally from the third oil port to the first spill valve.

In some embodiments, the first and second opposing cylinders are identical in structure, and in a state where the brake oil passage is communicated to the fourth and third oil ports, the first and fourth piston rods have the same stroke, and the second and third piston rods have the same stroke.

In some embodiments, the first steering arm is configured to control a steering action of a first steering wheel, the second steering arm is configured to control a steering action of a second steering wheel, the first steering arm is disposed at a centering position of the first steering wheel when the first opposing cylinder is in a stroke in which the first piston rod is fully extended and the second piston rod is fully retracted, and the second steering arm is disposed at a centering position of the second steering wheel when the second opposing cylinder is in a stroke in which the fourth piston rod is fully extended and the third piston rod is fully retracted.

In some embodiments, the first hydraulic valve block comprises:

a fourth directional control valve configured to communicate the first directional control port to the fifth port in a first operating position and to communicate the first directional control port to the first port in a second operating position; and

a fifth reversing valve configured to communicate the second steering port and the sixth port in a first operating position and communicate the second steering port and the second port in a second operating position.

In some embodiments, the first hydraulic valve block further comprises:

a sixth directional control valve configured to disconnect the first and fifth ports in a first operating position and to communicate the first and fifth ports in a second operating position;

a synchronization valve configured to divert hydraulic oil from the second steering oil port to the second oil port and the sixth oil port in a set proportion or to collect hydraulic oil from the second oil port and the sixth oil port to the second steering oil port in a set proportion;

a seventh reversing valve configured to communicate the second steering oil port and the fifth reversing valve in a first working position, and communicate the second steering oil port and the oil collecting port of the synchronizing valve in a second working position; and

and the eighth reversing valve is configured to communicate the two branch oil ports of the synchronizing valve in the first working position and conduct the fifth reversing valve and the second oil port, and the synchronizing valve and the sixth oil port in the second working position.

In some embodiments, the sixth directional valve is further configured to communicate the first port with the fourth directional valve in the first operating position, the fourth directional valve is further configured to communicate the first port with a return flow path in the first operating position, the eighth directional valve is further configured to communicate the second port with the fifth directional valve in the first operating position, and the fifth directional valve is further configured to communicate the eighth directional valve with a return flow path in the first operating position.

In some embodiments, the mode selection instruction comprises:

a first mode in which the fourth, fifth, sixth, seventh, and eighth directional valves are all set to a first operating position; and

in a second mode, the fourth directional valve and the fifth directional valve are all set to a second operating position, and the sixth directional valve, the seventh directional valve and the eighth directional valve are all set to a first operating position.

In some embodiments, the steering system further comprises:

a ninth directional control valve connected between the first hydraulic valve block and the first steering axle and configured to open the first steering port and the first oil port while opening the second steering port and the second oil port at a first operating position, and open the first steering port and the second oil port while opening the second steering port and the first oil port at a second operating position;

the mode selection instructions further comprise:

a third mode in which the fourth, fifth, and ninth directional control valves are each set to a first operating position, and the sixth, seventh, and eighth directional control valves are each set to a second operating position; and

in a fourth mode, the fourth and fifth directional control valves are set to a first operating position and the sixth, seventh and eighth directional control valves are set to a second operating position.

In some embodiments, the steering system further comprises:

a tenth directional valve connected between the steering gear and the first hydraulic valve bank and configured to selectively switch port locations of the first and second steering ports communicated to the first hydraulic valve bank.

In some embodiments, the second steering axle includes a first steering cylinder and a second steering cylinder, the rod chamber of the first steering cylinder and the rodless chamber of the second steering cylinder communicate with the fifth oil port, and the rodless chamber of the first steering cylinder and the rod chamber of the second steering cylinder communicate with the sixth oil port.

In some embodiments, the second steer axle further comprises:

the second overflow valve is arranged between the fifth oil port and the oil return flow path; and

and the third overflow valve is arranged between the sixth oil port and the oil return flow path.

In another aspect of the disclosure, a work machine is provided, comprising a steering system as described in any of the previous embodiments.

Therefore, according to the embodiments of the present disclosure, it is possible to improve convenience in operation of the steering system, reduce response time of the steering system under a control signal, and reduce a steering angle deviation of the steering system.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

The present disclosure may be more clearly understood from the following detailed description, taken with reference to the accompanying drawings, in which:

FIG. 1(a) is a schematic view of a steering system according to some embodiments of the present disclosure in a mode of front axle independent steering;

FIG. 1(b) is a schematic view of a steering system according to some embodiments of the present disclosure in a mode of rear axle independent steering;

fig. 1(c) is a schematic diagram of a mode of steering system in crab steering according to some embodiments of the present disclosure;

FIG. 1(d) is a schematic view of a steering system in a mode of tight turn steering according to some embodiments of the present disclosure;

FIG. 2 is a schematic diagram of an opposed steering cylinder configuration according to some embodiments of the present disclosure;

FIG. 3 is a schematic structural view of a diverter according to some embodiments of the present disclosure;

FIG. 4 is a schematic structural diagram of a steering system in a front axle independent steering state according to some embodiments of the present disclosure;

FIG. 5 is a schematic structural diagram of a steering system in a rear axle independent steering state according to some embodiments of the present disclosure;

FIG. 6 is a schematic block diagram of a steering system in a crab steering state, according to some embodiments of the present disclosure;

FIG. 7 is a schematic block diagram of a steering system in a tight turn steering state according to some embodiments of the present disclosure.

Reference numerals:

11, a first counter cylinder; 11a, a first piston rod; 11b, a second piston rod; 12, a second opposite oil cylinder; 12a, a third piston rod; 12b, a second piston rod;

2, a steering gear;

3, a second hydraulic valve group; 31, a first direction changing valve; 32, a second reversing valve; 33, a third directional valve; 34, a first relief valve; 35, a first one-way valve; 36, a second one-way valve;

4, a first steering axle;

5, a second steering axle; 51, a first steering cylinder; 52, a second steering cylinder; 53, a second overflow valve; 54, a third relief valve;

6, a first hydraulic valve group; 61, a fourth directional valve; 62, a fifth directional valve; 63, a sixth directional valve; 64, a synchronizing valve; 65, a seventh directional control valve; 66, an eighth diverter valve;

7, a ninth reversing valve;

8, a tenth reversing valve;

r1, a first steering port; l1, second steering port;

r2, a first oil port; l2, second oil port; r3, third oil port; l3, fourth port; r4, fifth port; l4, sixth oil port;

a, a brake oil way; and b, an oil supplementing oil path.

It should be understood that the dimensions of the various parts shown in the figures are not drawn to scale. Further, the same or similar reference numerals denote the same or similar components.

Detailed Description

Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the disclosure, its application, or uses. The present disclosure may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that: the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values set forth in these embodiments are to be construed as merely illustrative, and not as limitative, unless specifically stated otherwise.

The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element preceding the word covers the element listed after the word, and does not exclude the possibility that other elements are also covered. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

In the present disclosure, when a specific device is described as being located between a first device and a second device, there may or may not be intervening devices between the specific device and the first device or the second device. When a particular device is described as being coupled to other devices, that particular device may be directly coupled to the other devices without intervening devices or may be directly coupled to the other devices with intervening devices.

All terms (including technical or scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs unless specifically defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

The applicant researches and discovers that the conventional steering system of the engineering machinery generally adopts a steering system with an electro-hydraulic proportional valve, wherein the front axle wheels of the steering system are controlled by a driver through a steering wheel, and the rotating angles of the wheels of the rear axle are controlled by the driver through a set program in a controller under a steering mode selected by the driver, and the rotating angles of the corresponding front axle wheels output electric signals with different magnitudes, so that the opening degree of the electro-hydraulic proportional valve and the flow rate of hydraulic oil are controlled, and a rear wheel steering oil cylinder pushes the wheels of the rear axle to rotate according to the operation intention of the driver, thereby realizing the multi-mode steering function.

Specifically, the method comprises the following steps:

when the front axle is in independent steering, small-turning steering and crab steering modes, a driver operates the steering wheel to enable the steering gear to output hydraulic oil provided by the steering pump to the front axle oil cylinder according to the left-right rotation of the steering wheel, and meanwhile, the front axle sensor transmits a detected steering signal to the controller. And then, the controller calculates the required rotation angle of the rear axle and outputs corresponding control current to push the electro-hydraulic proportional valve according to the received steering signal and the steering mode instruction selected by the driver, so that hydraulic oil provided by the steering pump enters a rear axle steering oil cylinder through the electro-hydraulic proportional valve, and the rear axle is steered along with the front axle.

And when the rear axle is in the independent steering mode, a driver does not operate a steering wheel, and transmits a control signal to the controller by adjusting the external control knob, and the controller automatically calculates the required rotation angle of the rear axle according to the received control signal and outputs corresponding control current to push the electro proportional valve, so that hydraulic oil provided by the steering pump enters the rear axle steering oil cylinder through the electro proportional valve.

Therefore, the rear axle steering of the existing engineering machinery needs to be additionally controlled by an external control knob, cannot be controlled by a steering wheel, does not conform to the operation habit of a driver, and needs to return to the middle position to enable front and rear tires to return to the middle position and then switch in a steering mode, so that the operation convenience is poor; in addition, because the rear axle steering is controlled by the front axle steering signal, under the operation and response time difference of the hydraulic and electric control system, the front axle steering and the rear axle steering have certain time delay and angle deviation, so that the whole synchronism of the engineering machinery is insufficient, and the requirements on the accuracy and the reliability of a control system and elements are high.

In view of this, as shown in fig. 1 to 7, in one aspect of the present disclosure, there is provided a steering system including:

the first steering axle 4 is a double-opposite-cylinder steering axle and comprises a first oil port R2 and a second oil port L2;

a second steer axle 5 including a fifth oil port R4 and a sixth oil port L4;

the steering gear 2 which communicates the first port R2 and the fifth port R4 through a first steering port R1, communicates the second port L2 and the sixth port L4 through a second steering port L1, and is configured to control the flow direction of hydraulic oil of the first steering port R1 and the second steering port L1 according to a steering command; and

and a first hydraulic valve group 6 provided in a flow path of the steering gear 2 to the first steer axle 4 and the second steer axle 5 and configured to selectively communicate the first steering port R1 with the first port R2 and/or the fifth port R4 and selectively communicate the second steering port L1 with the second port L2 and/or the sixth port L4 according to a mode selection command.

According to the steering system provided by the disclosure, the first steering axle 4 and the second steering axle respectively control one steering axle, and the first hydraulic valve bank 6 controls the oil ports of the steering gear flowing to the first steering axle 4 and the second steering axle 5, so that the independent steering of the first steering axle and the second steering axle is realized. Each steering axle of the steering system is directly controlled by the steering wheel, and adverse effects brought by the reliability of an electric control system are eliminated while a rear axle external control knob is eliminated, so that the time delay of the steering system is reduced, and the respective rotation angle accuracy of the first steering axle 4 and the second steering axle is improved.

The first steering axle 4 adopts a double-opposite-oil-cylinder steering axle, and can realize mechanical centering of the corresponding control steering wheel, so that the steering system is more stable and reliable. In a preferred embodiment, the first steering axle 4 may be applied to a rear axle in a steering system, and the front axle may adopt a common steering cylinder form to control the manufacturing cost.

As shown in fig. 4-7, in some embodiments, the steering command includes a turning angle of a steering wheel, the first steer axle 4 is configured to implement a steering action of the first and second steer arms relative to the frame according to the steering command, the first steer axle 4 includes:

the first opposite oil cylinder 11 is connected with the first steering arm through a first piston rod 11a and is connected with the frame through a second piston rod 11 b; and

the second opposite oil cylinder 12 is connected with the frame through a third piston rod 12a and is connected with a second steering arm through a fourth piston rod 12 b;

the rod cavity of the first piston rod 11a and the rod cavity of the third piston rod 12a are communicated with the first oil port R2, the rod cavity of the second piston rod 11b and the rod cavity of the fourth piston rod 12b are communicated with the second oil port L2, the rod cavity of the second piston rod 11b and the rod cavity of the fourth piston rod 12b are communicated with the third oil port R3, and the rod cavity of the first piston rod 11a and the rod cavity of the third piston rod 12a are communicated with the fourth oil port L3.

The first oil port R2, the second oil port L2, the third oil port R3 and the fourth oil port L3 are arranged, so that the first piston rod 11a of the first opposing oil cylinder 11 and the third piston rod 12a of the second opposing oil cylinder extend synchronously, the second piston rod 11b of the first opposing oil cylinder 11 and the fourth piston rod 12b of the second opposing oil cylinder extend synchronously, and the second piston rod 11b and the third piston rod 12a are connected to the frame, so that the rotation angle synchronism of the two steering wheels controlled by the first steering axle 4 is high.

In some embodiments, in order to enable the first steering axle 4 to perform the steering and centering locking functions, the steering system further comprises:

and a second hydraulic valve group communicated with the brake oil path a and configured to selectively communicate the first port R2 or the brake oil path a with the third port R3 and selectively communicate the second port L2 or the brake oil path a with the fourth port L3 according to a steering command.

Specifically, in some embodiments, the second hydraulic valve group 3 includes:

a first direction change valve 31 configured to selectively communicate the first port R2 or the brake oil path a with the third port R3 according to a steering command; and

and a second direction valve 32 configured to selectively communicate the second port L2 or the brake oil path a with the fourth port L3 according to a steering command.

In the centered locked state, the first port R2 communicates with the third port R3, and the second port L2 communicates with the fourth port L3. At this time, under the control of the first hydraulic valve group 6, the steering oil flows from the first steering oil port R1 to the first oil port R2, and flows back to the second steering oil port L1 from the second oil port L2, at this time, under the action of hydraulic pressure, the inner cylinders of the two opposing cylinders are all retracted to the bottom, and the outer cylinders are all extended, so that the tire returns to the middle position, and the rear axle is always driven in a centered manner.

And under the state that the rear axle independently steers, the pressure oil output by the steering gear simultaneously enters the two cylinder barrels of the first opposite oil cylinder 11 and the two cylinder barrels of the second opposite oil cylinder 12 through the first hydraulic valve group 6 via the first oil port R2 and the second oil port L2, so that the inner oil cylinders of the two opposite oil cylinders are all extended, and the outer oil cylinders are all retracted to the bottom. At this time, under the pushing action of the high-pressure side hydraulic oil, the first direction valve 31 or the second direction valve 32 is changed, so that the steering oil enters the cylinder barrels on the corresponding sides of the first opposing cylinder 11 and the second opposing cylinder 12 through the third oil port R3 or the fourth oil port L3, thereby realizing the steering action.

Further, in order to control the cost and improve the reliability of the steering system, in some embodiments, the first direction valve 31 and the second direction valve 32 are both pilot-controlled direction valves, the pilot-controlled end of the first direction valve 31 is communicated with the first port R2, and the pilot-controlled end of the second direction valve 32 is communicated with the second port L2.

Of course, it is obvious to those skilled in the art that the first direction valve 31 and the second direction valve 32 may be solenoid valves, and in this case, the electronic control command of the solenoid valves may be directly controlled by the driver or may be associated with the steering gear.

Further, in order to realize the oil supplementing function of the first steering axle 4, in some embodiments, the second hydraulic valve set 3 is further communicated with the oil supplementing oil path b, and the second hydraulic valve set 3 further includes:

and a third direction change valve 33 configured to communicate the oil supply passage b with the first direction change valve 31 and the second direction change valve 32 or communicate the brake passage a with the first direction change valve 31 and the second direction change valve 32 according to a steering command.

Under the action of the third reversing valve 33, the oil supplementing oil path b enters the oil cylinder through the third reversing valve 33 and the first reversing valve 31 (or the second reversing valve 32), so that the cylinders of the first opposite oil cylinder 11 and the second opposite oil cylinder 12 are always full of oil, the phenomenon of steering failure or delay caused by air suction is prevented, and the accuracy and the sensitivity of a steering system are further improved.

Further, in order to ensure that the second hydraulic valve group 3 always operates in the safe oil pressure environment, in some embodiments, the second hydraulic valve group 3 further includes:

a first relief valve 34 provided between the return flow path and a junction of the fourth port L3 and the third port R3;

a first check valve 35 configured to allow only the hydraulic oil to flow unidirectionally from the fourth port L3 to the first relief valve 34; and

the second check valve 36 is configured to allow only the hydraulic oil to flow unidirectionally from the third port R3 to the first relief valve 34.

When the pressure of the reversing oil flowing through the first reversing valve 31 or the second reversing valve 32 rises to exceed the overflow pressure of the first overflow valve 34, part of the reversing oil will be discharged to the oil tank through the first check valve 35 or the second check valve 36, so that the oil flowing from the second hydraulic valve group 3 to the cylinder barrels of the first opposite cylinder 11 and the second opposite cylinder 12 is under the safety pressure, and the working safety of the steering system is ensured.

In order to facilitate control and maintenance replacement of the first and second opposing cylinders 11 and 12, in some embodiments, the first and second opposing cylinders 11 and 12 have the same structure, and in a state where the brake oil path a is communicated to the fourth oil port L3 and the third oil port R3, the strokes of the first and fourth piston rods 11a and 12b are the same, and the strokes of the second and third piston rods 11b and 12a are the same.

Further, in order to more accurately perform the centering operation on the steering wheel controlled by the first steering axle 4, in some embodiments, the first steering arm is configured to control the steering action of the first steering wheel, the second steering arm is configured to control the steering action of the second steering wheel, the first steering arm is disposed at the centering position of the first steering wheel when the first opposing cylinder 11 is in the stroke in which the first piston rod 11a is fully extended and the second piston rod 11b is fully retracted, and the second steering arm is disposed at the centering position of the second steering wheel when the second opposing cylinder 12 is in the stroke in which the fourth piston rod 12b is fully extended and the third piston rod 12a is fully retracted.

In order to achieve independent steering of the first steer axle 4 or the second steer axle 5, respectively, in some embodiments the first hydraulic valve pack 6 comprises:

a fourth switching valve 61 configured to communicate the first switching port R1 to the fifth port R4 in the first operating position, and communicate the first switching port R1 to the first port R2 in the second operating position; and

and a fifth direction switching valve 62 configured to communicate the second steering port L1 and the sixth port L4 in the first operating position and to communicate the second steering port L1 and the second port L2 in the second operating position.

As shown in fig. 4, when the fourth direction switching valve 61 is in the first working position and the fifth direction switching valve 62 is in the first working position, the first steering port R1 is communicated with the fifth port R4, the second steering port L1 is communicated with the sixth port L4, at this time, the second steering axle is actuated, the first steering axle is not actuated, and the steering system is in the mode of independent steering of the second steering axle.

As shown in fig. 5, when the fourth direction switching valve 61 is in the second working position and the fifth direction switching valve 62 is in the second working position, the first steering port R1 is communicated with the first port R2, the second steering port L1 is communicated with the second port L2, at this time, the first steering axle is actuated, the second steering axle is not actuated, and the steering system is in the mode of independent steering of the second steering axle.

In order to achieve smooth oil return of the steering system in the independent steering mode of the second steering axle 5, as shown in fig. 4, in some embodiments, the sixth direction valve 63 is further configured to communicate the first oil port R2 and the fourth direction valve 61 in the first working position, the fourth direction valve 61 is further configured to communicate the first oil port R2 and the oil return flow path in the first working position, the eighth direction valve 66 is further configured to communicate the second oil port L2 and the fifth direction valve 62 in the first working position, and the fifth direction valve 62 is further configured to communicate the eighth direction valve 66 and the oil return flow path in the first working position.

At this time, the first oil port R2 of the first steer axle 4 flows through the sixth direction valve 63 and the fourth direction valve 61 to the oil return flow path, and the second oil port L2 flows through the eighth direction valve 66 and the fifth direction valve 62 to the oil return flow path, so that the pressure build-up phenomenon of the first steer axle 4 which is not in the working state is avoided.

Further, to implement crab steering mode or tight turn steering mode, in some embodiments, the first hydraulic valve pack 6 further comprises:

a sixth direction valve 63 configured to disconnect the first port R2 and the fifth port R4 in the first operation position and to communicate the first port R2 and the fifth port R4 in the second operation position;

a synchronization valve 64 configured to divert hydraulic oil from the second steering port L1 to the second port L2 and the sixth port L4 in a set ratio or to collect hydraulic oil from the second port L2 and the sixth port L4 to the second steering port L1 in a set ratio;

a seventh direction changing valve 65 configured to communicate the second steering port L1 and the fifth direction changing valve 62 in the first operation position, and communicate the second steering port L1 and the collective port of the synchronizing valve 64 in the second operation position; and

and an eighth direction switching valve 66 configured to communicate the two branch ports of the synchronizing valve 64 and to communicate the fifth direction switching valve 62 with the second port L2 in the first operation position, and to communicate the synchronizing valve 64 with the sixth port L4 in the second operation position.

As shown in fig. 6 or 7, when the fourth directional valve 61 and the fifth directional valve 62 are set to the first operating position and the sixth directional valve 63, the seventh directional valve 65 and the eighth directional valve 66 are set to the second operating position, the first steering port R1 simultaneously communicates with the first port R2 and the fifth port R4, and the second steering port L1 simultaneously communicates with the second port L2 and the sixth port R4, and at this time, the second steering axle and the first steering axle both act, so that the steering system is in the crab steering mode or the tight-turn steering mode.

Corresponding to the above-described arrangement of the directional valves, in some embodiments, the mode selection command includes:

in the first mode, the fourth direction valve 61, the fifth direction valve 62, the sixth direction valve 63, the seventh direction valve 65 and the eighth direction valve 66 are all set to the first operating position; and

in the second mode, the fourth direction valve 61 and the fifth direction valve 62 are set to the second operating position, and the sixth direction valve 63, the seventh direction valve 65 and the eighth direction valve 66 are set to the first operating position.

In order to distinguish the crab steering mode from the tight steering mode, the steering system further includes:

a ninth directional control valve 7 connected between the first hydraulic valve group 6 and the first steering wheel axle 4 and configured to open the first steering port R1 and the first port R2 in the first operating position, to open the second steering port L1 and the second port L2 at the same time, to open the first steering port R1 and the second port L2 in the second operating position, and to open the second steering port L1 and the first port R2 at the same time;

the mode selection instructions further include:

in the third mode, the fourth direction switching valve 61, the fifth direction switching valve 62 and the ninth direction switching valve 7 are all set to the first operating position, and the sixth direction switching valve 63, the seventh direction switching valve 65 and the eighth direction switching valve 66 are all set to the second operating position; and

in the fourth mode, the fourth direction valve 61 and the fifth direction valve 62 are set to the first operation position, and the sixth direction valve 63, the seventh direction valve 65, the eighth direction valve 66 and the ninth direction valve 7 are set to the second operation position.

As shown in fig. 6, the ninth direction valve 7 is in the first working position, and at this time, the first direction oil port R1 is communicated to the first oil port R2, and the second direction oil port L1 is communicated to the second oil port L2, so that the steering action of the second steering axle is consistent with the steering action of the first steering axle, and the steering system is in the crab steering mode.

As shown in fig. 7, the ninth direction-changing valve 7 is at the second working position, and at this time, the first direction-changing oil port R1 is communicated to the second oil port L2, and the second direction-changing oil port L1 is communicated to the first oil port R2, so that the steering action of the second steering axle is opposite to the steering action of the first steering axle, and the steering system is in the tight turning steering mode.

Further, to increase the diversity of the steering modes, in some embodiments, the steering system further includes:

and a tenth direction change valve 8 connected between the steering gear 2 and the first hydraulic valve group 6 and configured to selectively switch the port positions of the first and second steering ports communicated to the first hydraulic valve group 6.

In some embodiments, the second steer axle 5 includes a first steer cylinder 51 and a second steer cylinder 52, the rod chamber of the first steer cylinder 51 and the rodless chamber of the second steer cylinder 52 communicating with the fifth port R4, and the rodless chamber of the first steer cylinder 51 and the rod chamber of the second steer cylinder 52 communicating with the sixth port L4.

In order to achieve smooth oil return of the steering system in the independent steering mode of the first steering axle 4, as shown in fig. 5, in some embodiments, the second steering axle 5 further comprises:

a second relief valve 53 provided between the fifth port R4 and the return flow path; and

the third relief valve 54 is provided between the sixth port L4 and the return flow path.

At this time, the fifth port R4 of the second steer axle 5 flows through the second relief valve 53 to the oil return flow path, and the sixth port L4 flows through the third relief valve 54 to the oil return flow path, so as to avoid the pressure holding phenomenon occurring in the second steer axle 5 which is not in the working state.

In another aspect of the disclosure, a work machine is provided, comprising a steering system as in any of the previous embodiments.

The present disclosure will be further described with reference to fig. 4-7, wherein the first steer axle 4 serves as the rear axle of the frame assembly and the second steer axle 5 serves as the front axle of the frame assembly:

as shown in fig. 4, the front axle is steered independently as the most common driving mode, the third reversing valve 33 in the rear axle opposite steering cylinder control valve group is not powered, the parking brake pressure oil enters the rear axle steering cylinder, under the control of hydraulic pressure, the inner cylinders of the double opposite cylinders of the rear axle are fully retracted to the bottom, the outer cylinders are fully extended, and the tires of the rear axle are in the middle position. And hydraulic oil enters the front axle hydraulic oil cylinder through the second hydraulic valve group 6, so that the front axle is steered under the action of hydraulic pressure.

As shown in figure 5, the rear axle independently turns downwards, the second hydraulic valve group 6 disconnects the steering gear from being communicated with the front axle hydraulic oil cylinder, and the front axle does not act. Pressure oil output by the steering gear simultaneously enters corresponding cylinder barrels of oil cylinders on the left side and the right side of the rear axle through the second hydraulic valve group 6 and the first oil port R2 or the second oil port L2, high-pressure side hydraulic oil pushes the first reversing valve 31 (or the second reversing valve 32) to reverse, so that the steering oil respectively enters the third oil port R3 (or the fourth oil port L4) on the other side of the opposite cylinder, at the moment, the first oil port R2 or the second oil port L2 of the opposite steering oil cylinder is communicated with an oil return circuit of the steering gear, and meanwhile, the third reversing valve 33 is electrified, so that the third oil port R3 (or the fourth oil port L4) of the opposite steering oil cylinder is communicated with an oil supplementing loop, and therefore the pressure oil pushes the lower rear axle to realize steering action.

As shown in fig. 6, in the crab-walking bending mode, on the basis of the rear axle independent steering mode, the pressure oil of the steering gear enters the rear axle opposite steering oil cylinder and enters the front axle oil cylinder through the second hydraulic valve group 6, so that the synchronous steering of the front axle and the rear axle is realized, and the rotation directions of the front axle and the rear axle are the same.

As shown in fig. 7, in the tight turning mode, on the basis of the crab bend mode, the ninth directional control valve 7 in the second hydraulic valve set 6 switches the steering gear to enter the oil path of the opposite steering cylinder of the rear axle, while the front axle remains unchanged, so the rotation directions of the front axle and the rear axle are opposite, that is, the front axle turns left, the rear axle turns right (or the axle turns right, the rear axle turns left), and then the minimum turning radius is realized.

Therefore, according to the embodiment of the disclosure, four modes of independent front axle steering, independent rear axle steering, crab steering and small-turning steering of the steering system are directly controlled by the steering wheel, a rear axle control knob is omitted, and the operation convenience is improved; the double-opposite steering oil cylinder control valve group is added with an oil supplementing function, so that the phenomena of steering delay and steering control failure are avoided; in addition, the full hydraulic steering control is realized, and the rear axle adopts mechanical centering, so that the system is more stable and reliable. That is, the present disclosure can improve the convenience of the operation of the steering system, reduce the response time of the steering system under the control signal, and reduce the deviation of the steering angle of the steering system.

Thus, various embodiments of the present disclosure have been described in detail. Some details that are well known in the art have not been described in order to avoid obscuring the concepts of the present disclosure. It will be fully apparent to those skilled in the art from the foregoing description how to practice the presently disclosed embodiments.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. It will be understood by those skilled in the art that various changes may be made in the above embodiments or equivalents may be substituted for elements thereof without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims (17)

1. A steering system, comprising:

the first steering axle (4) is a double-opposite-cylinder steering axle and comprises a first oil port (R2) and a second oil port (L2);

a second steer axle (5) including a fifth oil port (R4) and a sixth oil port (L4);

a steering gear (2) communicating the first port (R2) and the fifth port (R4) through a first steering port (R1), and communicating the second port (L2) and the sixth port (L4) through a second steering port (L1), and configured to control a hydraulic oil flow direction of the first steering port (R1) and the second steering port (L1) according to a steering command; and

a first hydraulic valve group (6) disposed in a flow path of the steering gear (2) to the first steering axle (4) and the second steering axle (5) and configured to selectively communicate the first steering port (R1) with the first port (R2) and/or the fifth port (R4) and selectively communicate the second steering port (L1) with the second port (L2) and/or the sixth port (L4) according to a mode selection command;

wherein the steering command comprises a turning angle of a steering wheel, the first steer axle (4) is configured to effect a steering action of a first steer arm and a second steer arm relative to a frame according to the steering command, the first steer axle (4) comprises:

the first opposite oil cylinder (11) is connected with the first steering arm through a first piston rod (11a) and is connected with the frame through a second piston rod (11 b); and

the second opposite oil cylinder (12) is connected with the frame through a third piston rod (12a) and is connected with the second steering arm through a fourth piston rod (12 b);

the first piston rod (11a) is provided with a rod cavity and the third piston rod (12a) is provided with a rod cavity which is communicated with a first oil port (R2), the second piston rod (11b) is provided with a rod cavity and the fourth piston rod (12b) is provided with a rod cavity which is communicated with a second oil port (L2), the second piston rod (11b) is provided with a rod cavity and the fourth piston rod (12b) is provided with a rod cavity which is communicated with a third oil port (R3), and the first piston rod (11a) is provided with a rod cavity and the third piston rod (12a) is provided with a rod cavity which is communicated with a fourth oil port (L3).

2. The steering system of claim 1, further comprising:

a second hydraulic valve group communicated with a brake oil path (a) and configured to selectively communicate the first port (R2) or the brake oil path (a) with the third port (R3) and selectively communicate the second port (L2) or the brake oil path (a) with the fourth port (L3) according to the steering command.

3. A steering system according to claim 2, characterized in that said second hydraulic valve group (3) comprises:

a first direction change valve (31) configured to selectively communicate the first port (R2) or the brake oil path (a) with the third port (R3) according to the steering command; and

a second direction change valve (32) configured to selectively communicate the second port (L2) or the brake oil path (a) with the fourth port (L3) according to the steering command.

4. The steering system of claim 3, wherein the first directional valve (31) and the second directional valve (32) are both pilot operated directional valves, a pilot operated end of the first directional valve (31) is communicated with the first port (R2), and a pilot operated end of the second directional valve (32) is communicated with the second port (L2).

5. A steering system according to claim 4, wherein the second hydraulic valve group (3) is further in communication with an oil supply circuit (b), the second hydraulic valve group (3) further comprising:

a third direction change valve (33) configured to communicate the oil supply passage (b) with the first direction change valve (31) and the second direction change valve (32) or communicate the brake oil passage (a) with the first direction change valve (31) and the second direction change valve (32) according to the steering command.

6. A steering system according to claim 3, wherein said second hydraulic valve group (3) further comprises:

a first relief valve (34) provided between a return flow path and a junction of the fourth port (L3) and the third port (R3);

a first check valve (35) configured to allow only hydraulic oil to flow unidirectionally from the fourth oil port (L3) to the first spill valve (34); and

a second check valve (36) configured to allow only hydraulic oil to flow unidirectionally from the third oil port (R3) to the first relief valve (34).

7. The steering system according to claim 3, wherein the first and second opposing cylinders (11, 12) are identical in structure, and the strokes of the first and fourth piston rods (11a, 12b) are identical and the strokes of the second and third piston rods (11b, 12a) are identical in a state where the brake oil passage (a) is communicated to the fourth and third oil ports (L3, R3).

8. The steering system according to claim 7, wherein the first steering arm is configured to control a steering action of a first steering wheel, the second steering arm is configured to control a steering action of a second steering wheel, the first steering arm is disposed at a centering position of the first steering wheel when the first opposing cylinder (11) is in a stroke in which the first piston rod (11a) is fully extended and the second piston rod (11b) is fully retracted, and the second steering arm is disposed at a centering position of the second steering wheel when the second opposing cylinder (12) is in a stroke in which the fourth piston rod (12b) is fully extended and the third piston rod (12a) is fully retracted.

9. A steering system according to claim 1, characterized in that said first hydraulic valve group (6) comprises:

a fourth direction valve (61) configured to communicate the first direction port (R1) to the fifth port (R4) in a first operation position, and to communicate the first direction port (R1) to the first port (R2) in a second operation position; and

a fifth direction valve (62) configured to communicate the second steering oil port (L1) and the sixth oil port (L4) in the first working position, and to communicate the second steering oil port (L1) and the second oil port (L2) in the second working position.

10. A steering system according to claim 9, wherein said first hydraulic valve group (6) further comprises:

a sixth direction valve (63) configured to disconnect the first port (R2) and the fifth port (R4) in a first operation position, and to communicate the first port (R2) and the fifth port (R4) in a second operation position;

a synchronization valve (64) configured to divert hydraulic oil from the second steering oil port (L1) to the second and sixth oil ports (L2, L4) in a set ratio or to collect hydraulic oil from the second and sixth oil ports (L2, L4) to the second steering oil port (L1) in a set ratio;

a seventh direction changing valve (65) configured to communicate the second steering oil port (L1) and the fifth direction changing valve (62) at a first working position, and communicate the second steering oil port (L1) and the collecting oil port of the synchronizing valve (64) at a second working position; and

an eighth direction switching valve (66) configured to communicate the two branch ports of the synchronizing valve (64) and communicate the fifth direction switching valve (62) with the second port (L2) in a first operating position, and to communicate the synchronizing valve (64) with the sixth port (L4) in a second operating position.

11. The steering system of claim 10, wherein the sixth direction valve (63) is further configured to communicate the first port (R2) and the fourth direction valve (61) in the first operating position, the fourth direction valve (61) is further configured to communicate the first port (R2) and a return flow path in the first operating position, the eighth direction valve (66) is further configured to communicate the second port (L2) and the fifth direction valve (62) in the first operating position, and the fifth direction valve (62) is further configured to communicate the eighth direction valve (66) and the return flow path in the first operating position.

12. The steering system of claim 11, wherein the mode selection instruction comprises:

a first mode in which the fourth direction valve (61), the fifth direction valve (62), the sixth direction valve (63), the seventh direction valve (65) and the eighth direction valve (66) are all set to a first operating position; and

in a second mode, the fourth directional control valve (61), the fifth directional control valve (62) are each set to a second operating position, and the sixth directional control valve (63), the seventh directional control valve (65), and the eighth directional control valve (66) are each set to a first operating position.

13. The steering system of claim 12, further comprising:

a ninth direction change valve (7) connected between the first hydraulic valve group (6) and the first steering wheel axle (4) and configured to open the first steering port (R1) and the first port (R2) in a first working position, simultaneously open the second steering port (L1) and the second port (L2), open the first steering port (R1) and the second port (L2) in a second working position, simultaneously open the second steering port (L1) and the first port (R2);

the mode selection instructions further comprise:

a third mode in which the fourth directional control valve (61), the fifth directional control valve (62) and the ninth directional control valve (7) are all set to a first operating position, and the sixth directional control valve (63), the seventh directional control valve (65) and the eighth directional control valve (66) are all set to a second operating position; and

a fourth mode in which the fourth direction valve (61) and the fifth direction valve (62) are set to a first operating position, and the sixth direction valve (63), the seventh direction valve (65), the eighth direction valve (66) and the ninth direction valve (7) are all set to a second operating position.

14. The steering system of claim 13, further comprising:

a tenth directional valve (8) connected between the steering gear (2) and the first hydraulic valve block (6) and configured to selectively switch port positions of the first and second steering ports to the first hydraulic valve block (6).

15. The steering system according to claim 1, wherein the second steering axle (5) includes a first steering cylinder (51) and a second steering cylinder (52), the rod chamber of the first steering cylinder (51) and the rodless chamber of the second steering cylinder (52) communicating with the fifth port (R4), and the rodless chamber of the first steering cylinder (51) and the rod chamber of the second steering cylinder (52) communicating with the sixth port (L4).

16. Steering system according to claim 15, characterized in that the second steering axle (5) further comprises:

a second relief valve (53) provided between the fifth port (R4) and the return flow path; and

and a third relief valve (54) provided between the sixth port (L4) and the return flow path.

17. A working machine, characterized by comprising a steering system according to any one of claims 1-16.

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