阅读说明：本技术 车辆的行走转向液压系统和高空作业平台 (Walking steering hydraulic system of vehicle and aerial work platform ) 是由 陈豪 刘治军 周云生 于 2020-07-31 设计创作，主要内容包括：本公开提供一种车辆的行走转向液压系统和高空作业平台。行走转向液压系统包括：液压泵,被配置为向行走转向液压系统提供液压油；执行元件,包括用于车辆执行行走动作的行走马达和用于车辆执行转向动作的转向油缸,行走马达与转向油缸相互并联；和控制阀组,包括设置于液压泵和执行元件之间的液控阀,液控阀和执行元件之间设置有反馈油路,反馈油路被配置为反馈转向油缸的负载,液控阀被配置为根据反馈油路的压力调节自身工作状态,以向行走马达和转向油缸分配液压油的流量。高空作业平台包括前述行走转向液压系统。本公开可以改善行走转向液压系统的流量分配情况和压力叠加现象,利于车辆节省能量和适应复杂的工况条件。(The disclosure provides a walking steering hydraulic system of a vehicle and an aerial work platform. The walking steering hydraulic system comprises: a hydraulic pump configured to supply hydraulic oil to the walk steering hydraulic system; the executing element comprises a walking motor and a steering oil cylinder, wherein the walking motor is used for the vehicle to execute walking motion, the steering oil cylinder is used for the vehicle to execute steering motion, and the walking motor and the steering oil cylinder are mutually connected in parallel; and the control valve group comprises a hydraulic control valve arranged between the hydraulic pump and the executing element, a feedback oil path is arranged between the hydraulic control valve and the executing element, the feedback oil path is configured to feed back the load of the steering oil cylinder, and the hydraulic control valve is configured to adjust the working state of the hydraulic control valve according to the pressure of the feedback oil path so as to distribute the flow of hydraulic oil to the walking motor and the steering oil cylinder. The aerial work platform comprises the walking steering hydraulic system. The method can improve the flow distribution condition and the pressure superposition phenomenon of the walking steering hydraulic system, is beneficial to saving energy of vehicles and adapts to complex working conditions.)

1. A walk steering hydraulic system for a vehicle, comprising:

a hydraulic pump (1) configured to provide hydraulic oil to the walking steering hydraulic system;

the actuating element comprises a walking motor (8) for the vehicle to perform walking action and a steering oil cylinder (7) for the vehicle to perform steering action, and the walking motor (8) and the steering oil cylinder (7) are mutually connected in parallel; and

and the control valve group comprises a hydraulic control valve (3) arranged between the hydraulic pump (1) and the executing element, a feedback oil path is arranged between the hydraulic control valve (3) and the executing element, the feedback oil path is configured to feed back the load of the steering oil cylinder (7), and the hydraulic control valve (3) is configured to adjust the working state of the hydraulic control valve according to the pressure of the feedback oil path so as to distribute the flow of hydraulic oil to the walking motor (8) and the steering oil cylinder (7).

2. Walking steering hydraulic system according to claim 1, characterized in that the pilot-controlled valve (3) has:

the oil inlet (30) is connected with an oil outlet of the hydraulic pump (1);

a first oil outlet (31) connected to the travel motor (8);

a second oil outlet (32) connected to the steering cylinder (7);

the control oil port is connected to the feedback oil path; and

and the valve core is communicated with the oil inlet (30) and at least one of the first oil outlet (31) and the second oil outlet (32) along with a hydraulic signal of the control oil port.

3. The walking steering hydraulic system according to claim 2, wherein the spool of the pilot control valve (3) has a first working position and a second working position, when the spool of the pilot control valve (3) is located at the first working position, the oil inlet (30) of the pilot control valve (3) is communicated with the first oil outlet (31) of the pilot control valve (3), the hydraulic pump (1) supplies oil to the walking motor (8) alone, when the spool of the pilot control valve (3) is located at the second working position, the oil inlet (30) of the pilot control valve (3) is communicated with the second oil outlet (32) of the pilot control valve (3), the hydraulic pump (1) supplies oil to the steering cylinder (7) alone, and when the spool of the pilot control valve (3) is located between the first working position and the second working position, the oil inlet (30) of the pilot control valve (3) is communicated with the first oil outlet (31) and the second oil outlet (32) of the pilot control valve (3) The oil port (32) is communicated, and the hydraulic pump (1) supplies oil to the traveling motor (8) and the steering oil cylinder (7) simultaneously.

4. The walk steering hydraulic system of claim 3, wherein the control valve set comprises:

a first direction change valve (5) disposed between the pilot-controlled valve (3) and the travel motor (8), the first direction change valve (5) being configured to switch a rotation direction of the travel motor (8); and/or

A second direction change valve (6) disposed between the pilot operated valve (3) and the steering cylinder (7), the second direction change valve (6) being configured to switch a moving direction of a movable part of the steering cylinder (7).

5. The walking steering hydraulic system according to claim 4, wherein an oil inlet (51) of the first reversing valve (5) is connected with a first oil outlet (31) of the hydraulic control valve (3), an oil outlet (52) of the first reversing valve (5) is connected with an oil discharge pipeline, and a first working oil port (53) and a second working oil port (54) of the first reversing valve (5) are respectively connected with two working oil ports of the walking motor (8).

6. Walking steering hydraulic system according to claim 4,

the control oil ports of the hydraulic control valve (3) comprise a first control oil port (33) and a second control oil port (34), and the first control oil port (33) of the hydraulic control valve (3) is connected with the second oil port (32) of the hydraulic control valve (3);

an oil inlet (61) of the second reversing valve (6) is connected with a second oil outlet (32) of the hydraulic control valve (3), an oil outlet (62) of the second reversing valve (6) is connected with an oil discharge pipeline, a first working oil port (63) and a second working oil port (64) of the second reversing valve (6) are respectively connected with two working oil ports of the steering oil cylinder (7), and a feedback oil port (65) of the second reversing valve (6) is connected with a second control oil port (34) of the hydraulic control valve (3);

the second reversing valve (6) is provided with a first working position, a second working position and a third working position, wherein in the first working position of the second reversing valve (6), a first oil cavity of the steering oil cylinder (7) is filled with oil, an oil inlet (61) of the second reversing valve (6) is communicated with the feedback oil port (65), in the second working position of the second reversing valve (6), a second oil cavity of the steering oil cylinder (7) is filled with oil, the oil inlet (61) of the second reversing valve (6) is communicated with the feedback oil port (65), in the third working position of the second reversing valve (6), the steering oil cylinder (7) stops, and the oil outlet (62) of the second reversing valve (6) is communicated with the feedback oil port (65).

7. The walking steering hydraulic system according to claim 1, wherein the control valve group comprises a first overflow valve (2), an oil inlet of the first overflow valve (2) is connected with an oil outlet of the hydraulic pump (1) and an oil inlet of the hydraulic control valve (3), and an oil outlet of the first overflow valve (2) is connected with an oil discharge pipeline.

8. The walking steering hydraulic system according to claim 1, wherein the control valve group comprises a second overflow valve (4), an oil inlet of the second overflow valve (4) is connected with the feedback oil path, and an oil outlet of the second overflow valve (4) is connected with an oil discharge line.

9. Walking steering hydraulic system according to any one of claims 1 to 8, characterized in that the pilot-controlled valve (3) is a static load-sensing pressure compensation valve.

10. Walking steering hydraulic system according to any one of claims 1-8, characterized in that a throttle valve (9) is arranged between the pilot-controlled valve (3) and the steering cylinder (7).

11. An aerial work platform, comprising:

a chassis comprising a walking steering hydraulic system according to any one of claims 1 to 10, a walking mechanism in driving connection with the walking motor (8) of the walking steering hydraulic system and a steering mechanism in driving connection with the steering cylinder (7) of the walking steering hydraulic system; and

and the lifting platform is arranged on the chassis.

Technical Field

The disclosure relates to the technical field of hydraulic pressure, in particular to a walking steering hydraulic system and an aerial work platform.

Background

The walking steering system is one of important components of the engineering vehicle. The walking steering system needs to have good controllability and safety so as to enable the whole vehicle operation process to be flexible and efficient.

The walking steering hydraulic system of the existing scissor-type aerial work platform mainly distributes the flow of a walking oil way and a steering oil way through a pressure compensation flow regulating valve. However, this flow rate distribution method is relatively fixed, and because this flow rate distribution method requires connecting the return line of the steering oil path to the traveling oil path, a pressure superposition phenomenon occurs in the traveling oil path and the steering oil path. On one hand, the phenomenon can cause the vehicle to do steering action in the walking process and have larger energy loss; on the other hand, when the steering operation is performed under a condition where a traveling load is relatively large, such as climbing, the steering is not performed even when the vehicle is not traveling.

Disclosure of Invention

The invention aims to provide a walking steering hydraulic system of a vehicle and an aerial work platform, so as to improve the flow distribution condition and the pressure superposition phenomenon of the walking steering hydraulic system.

A first aspect of the present disclosure provides a walk steering hydraulic system of a vehicle, including:

a hydraulic pump configured to provide hydraulic oil to the walk steering hydraulic system;

the actuating element comprises a walking motor and a steering oil cylinder, wherein the walking motor is used for a vehicle to perform walking motion, the steering oil cylinder is used for the vehicle to perform steering motion, and the walking motor and the steering oil cylinder are mutually connected in parallel; and

and the control valve group comprises a hydraulic control valve arranged between the hydraulic pump and the executing element, a feedback oil path is arranged between the hydraulic control valve and the executing element, the feedback oil path is configured to feed back the load of the steering oil cylinder, and the hydraulic control valve is configured to adjust the working state of the hydraulic control valve according to the pressure of the feedback oil path so as to distribute the flow of hydraulic oil to the walking motor and the steering oil cylinder.

According to some embodiments of the present disclosure, the pilot operated valve has:

the oil inlet is connected with an oil outlet of the hydraulic pump;

the first oil outlet is connected with the walking motor;

the second oil outlet is connected to the steering oil cylinder;

the control oil port is connected to the feedback oil path; and

and the valve core is communicated with the oil inlet and at least one of the first oil outlet and the second oil outlet along with a hydraulic signal of the control oil port.

According to some embodiments of the present disclosure, the spool of the hydraulic control valve has a first working position and a second working position, when the spool of the hydraulic control valve is located at the first working position, the oil inlet of the hydraulic control valve is communicated with the first oil outlet of the hydraulic control valve, the hydraulic pump supplies oil to the traveling motor alone, when the spool of the hydraulic control valve is located at the second working position, the oil inlet of the hydraulic control valve is communicated with the second oil outlet of the hydraulic control valve, the hydraulic pump supplies oil to the steering cylinder alone, when the spool of the hydraulic control valve is located between the first working position and the second working position, the oil inlet of the hydraulic control valve is communicated with the first oil outlet and the second oil outlet of the hydraulic control valve, and the hydraulic pump supplies oil to the traveling motor and the steering cylinder simultaneously.

According to some embodiments of the disclosure, the control valve block comprises:

a first direction change valve disposed between the hydraulic control valve and the travel motor, the first direction change valve configured to switch a rotation direction of the travel motor; and/or

A second direction change valve provided between the pilot-controlled valve and the steering cylinder, the second direction change valve being configured to switch a moving direction of a movable part of the steering cylinder.

According to some embodiments of the present disclosure, an oil inlet of the first reversing valve is connected to a first oil outlet of the hydraulic control valve, an oil outlet of the first reversing valve is connected to an oil discharge pipeline, and a first working oil port and a second working oil port of the first reversing valve are respectively connected to two working oil ports of the traveling motor.

In accordance with some embodiments of the present disclosure,

the control oil port of the hydraulic control valve comprises a first control oil port and a second control oil port, and the first control oil port of the hydraulic control valve is connected with the second oil outlet of the hydraulic control valve;

an oil inlet of the second reversing valve is connected with a second oil outlet of the hydraulic control valve, an oil outlet of the second reversing valve is connected with an oil discharge pipeline, a first working oil port and a second working oil port of the second reversing valve are respectively connected with two working oil ports of the steering oil cylinder, and a feedback oil port of the second reversing valve is connected with a second control oil port of the hydraulic control valve;

the second reversing valve is provided with a first working position, a second working position and a third working position, in the first working position of the second reversing valve, the first oil cavity of the steering oil cylinder is filled with oil, the oil inlet of the second reversing valve is communicated with the feedback oil port, in the second working position of the second reversing valve, the second oil cavity of the steering oil cylinder is filled with oil, the oil inlet of the second reversing valve is communicated with the feedback oil port, in the third working position of the second reversing valve, the steering oil cylinder stops, and the oil outlet of the second reversing valve is communicated with the feedback oil port.

According to some embodiments of the present disclosure, the control valve group includes a first overflow valve, an oil inlet of the first overflow valve is connected to an oil outlet of the hydraulic pump and an oil inlet of the hydraulic control valve, and an oil outlet of the first overflow valve is connected to an oil discharge line.

According to some embodiments of the present disclosure, the control valve group includes a second overflow valve, an oil inlet of the second overflow valve is connected to the feedback oil path, and an oil outlet of the second overflow valve is connected to the oil discharge line.

According to some embodiments of the disclosure, the pilot operated valve is a static load sensing pressure compensating valve.

According to some embodiments of the disclosure, a throttle valve is disposed between the pilot operated valve and the steering cylinder.

A second aspect of the present disclosure provides an aerial work platform comprising:

the chassis comprises a walking steering hydraulic system, a walking mechanism in driving connection with the walking motor of the walking steering hydraulic system and a steering mechanism in driving connection with the steering oil cylinder of the walking steering hydraulic system; and

and the lifting platform is arranged on the chassis.

According to the walking steering hydraulic system, the feedback oil way is arranged between the hydraulic control valve and the executing element, the pressure of the feedback oil way reflects the load condition of the vehicle for executing steering action, the working state of the hydraulic control valve is adjusted according to the pressure of the feedback oil way, the hydraulic control valve can be adjusted to reasonably distribute the flow of hydraulic oil, and meanwhile, the walking motor and the steering oil cylinder are connected in parallel, so that the pressure superposition phenomenon of the hydraulic system can be improved. The high-altitude operation platform adopts the walking steering hydraulic system, so that the cruising ability, the controllability and the safety of the high-altitude operation platform can be improved.

Other features of the present disclosure and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the disclosure and not to limit the disclosure. In the drawings:

fig. 1 is a hydraulic schematic diagram of a related art walk steering system.

FIG. 2 is a hydraulic schematic of a walk steering system according to some embodiments of the present disclosure.

In fig. 1, the respective reference numerals denote:

1', a fixed displacement pump; 2', a first overflow valve; 3', a pressure compensation flow regulating valve; 30', an oil inlet of a pressure compensation flow regulating valve; 31', a first oil outlet of the pressure compensation flow regulating valve; 32', a second oil outlet of the pressure compensation flow regulating valve; 4', a second overflow valve; 5', a one-way valve; 6' and a second electromagnetic directional valve; 7', a steering oil cylinder; 8', a first electromagnetic directional valve; 9', a first travel motor; 10' and a second travel motor.

In fig. 2, the respective reference numerals denote:

1. a hydraulic pump; 2. a first overflow valve; 3. a hydraulic control valve; 30. an oil inlet of the hydraulic control valve; 31. a first oil outlet of the hydraulic control valve; 32. a second oil outlet of the hydraulic control valve; 33. a first control oil port of the hydraulic control valve; 34. a second control oil port of the hydraulic control valve; 4. a second overflow valve; 5. a first direction changing valve; 51. an oil inlet of the first reversing valve; 52. an oil outlet of the first reversing valve; 53. a first working oil port of the first reversing valve; 54. a second working oil port of the first reversing valve; 6. a second directional control valve; 61. an oil inlet of the second reversing valve; 62. an oil outlet of the second reversing valve; 63. a first working oil port of the second reversing valve; 64. a second working oil port of the second reversing valve; 65. a feedback oil port of the second reversing valve; 7. a steering cylinder; 8. a travel motor; 81. a first travel motor; 82. a second travel motor; 9. a throttle valve.

Detailed Description

The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are only a part of the embodiments of the present disclosure, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.

The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. 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. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present disclosure, it should be understood that the terms "first", "second", etc. are used to define the components, and are used only for convenience of distinguishing the corresponding components, and if not otherwise stated, the terms have no special meaning, and thus, should not be construed as limiting the scope of the present disclosure.

Fig. 1 is a hydraulic schematic diagram of a walking steering hydraulic system of a vehicle in the related art. The walking steering system comprises a fixed displacement pump 1 ', a first overflow valve 2', a pressure compensation flow regulating valve 3 ', a second overflow valve 4', a one-way valve 5 ', a first electromagnetic directional valve 8', a first walking motor 9 ', a second walking motor 10', a second electromagnetic directional valve 6 'and a steering oil cylinder 7'.

The pressure compensation flow regulating valve 3 'can distribute the hydraulic oil provided by the fixed displacement pump 1' to the second oil outlet 32 'at a constant flow rate preferentially, so that the constant flow rate of the hydraulic oil is provided to the steering oil path to meet the requirement that the vehicle can perform steering action under any working condition, and the rest of the hydraulic oil is distributed to the first oil outlet 31' and provided to the walking oil path.

In the process of implementing the technical scheme of the present disclosure, the inventor finds that the walking steering hydraulic system shown in fig. 1 has the following problems:

firstly, when the walking steering hydraulic system performs steering action, extra energy loss is generated;

second, when the traveling load is relatively large, for example, when traveling on a slope, the vehicle does not have a traveling operation nor a steering operation.

The inventors analyzed the causes of the above problems as follows:

if the vehicle only moves and does not turn, the second electromagnetic directional valve 6 'is in the middle position, the hydraulic oil distributed to the second oil outlet 32' through the pressure compensation flow regulating valve 3 'flows to the one-way valve 5' through the second electromagnetic directional valve 6 ', and then flows to the walking oil way through the one-way valve 5', and all the hydraulic oil is supplied to the walking oil way at the moment so as to ensure the effective use of energy.

However, if the vehicle is turning while walking, the second electromagnetic directional valve 6 'is energized, the hydraulic oil distributed to the second oil outlet 32' in the pressure compensation flow control valve 3 'flows to the oil inlet chamber of the steering oil cylinder 7' through the second electromagnetic directional valve 6 ', the piston rod of the steering oil cylinder 7' is pushed to move, the steering action is executed, the hydraulic oil in the oil return chamber of the steering oil cylinder 7 'flows to the check valve 5' through the second electromagnetic directional valve 6 ', and since the port b of the check valve 5' is connected with the walking oil path, the pressure at the port a is equal to the pressure of the walking oil path plus the pressure of the steering oil path, i.e., a pressure superposition phenomenon is generated.

The fixed displacement pump 1' is driven by a direct current motor, and the output power of the motor is determined by load, so that the steering oil circuit needs energy of a load of a walking oil circuit and a load of the steering oil circuit, the whole hydraulic system consumes more energy of one walking load, and extra energy loss is generated when a vehicle does not only have walking action but also has steering action.

When the pressure of a running oil path of a vehicle is relatively high, for example, when the vehicle climbs a slope, the pressure of the running oil path is very high, at this time, if a steering action is required, pressure superposition is caused, after the pressure superposition, the pressure at the outlet of the fixed displacement pump 1 'exceeds the set pressure of the first overflow valve 2', at this time, the output flow of the fixed displacement pump 1 'flows into an oil return tank through the first overflow valve 2', hydraulic oil with insufficient flow is not provided for the steering action and the running action, and the phenomenon that the vehicle does not run or steer is caused.

In view of the above problem, some embodiments of the present disclosure provide a walk steering hydraulic system of a vehicle, as shown in fig. 2, to improve the above problem.

The walking steering hydraulic system of the embodiment of the disclosure comprises a hydraulic pump 1, an actuating element and a control valve group.

The hydraulic pump 1 is configured to supply hydraulic oil to the walking steering hydraulic system, and may be driven by a motor. The executing element comprises a walking motor 8 for the vehicle to execute walking action and a steering oil cylinder 7 for the vehicle to execute steering action, and the walking motor 8 and the steering oil cylinder 7 are mutually connected in parallel. The travel motor 8 may include a first travel motor 81 and a second travel motor 82, and the first travel motor 81 and the second travel motor 82 may be connected in series or in parallel according to the operating condition of the vehicle. The pilot valve group includes a pilot valve 3 disposed between the hydraulic pump 1 and the actuator, a feedback oil path is disposed between the pilot valve 3 and the actuator, the feedback oil path is configured to feed back a load of the steering cylinder 7, and the pilot valve 3 is configured to adjust an operating state of the pilot valve 3 according to a pressure of the feedback oil path to distribute a flow rate of hydraulic oil to the traveling motor 8 and the steering cylinder 7.

According to the walking steering hydraulic system, the feedback oil way is arranged between the hydraulic control valve and the executing element, the pressure of the feedback oil way reflects the load condition of the vehicle for executing steering action, the working state of the hydraulic control valve is adjusted according to the pressure of the feedback oil way, the hydraulic control valve is favorably adjusted to reasonably distribute the flow of hydraulic oil, and meanwhile, the walking motor and the steering oil cylinder are connected in parallel, so that the pressure superposition phenomenon of the hydraulic system can be improved.

In some embodiments, the pilot controlled valve 3 has an oil inlet 30, a first oil outlet 31, a second oil outlet 32, a control oil port, and a spool. The oil inlet 30 is connected with an oil outlet of the hydraulic pump 1. The first oil outlet 31 is connected to the traveling motor 8. The second oil outlet 32 is connected to the steering cylinder 7. The control oil port is connected to the feedback oil path to receive a hydraulic signal that varies according to a load condition of the vehicle. The valve core is communicated with the oil inlet 30 and at least one of the first oil outlet 31 and the second oil outlet 32 along with the hydraulic signal of the control oil port. According to the different load conditions of the vehicle, the valve core of the hydraulic control valve 3 can move correspondingly to change the opening degree of the first oil outlet 31 and the second oil outlet 32, and further change the flow rate of the hydraulic oil distributed to the walking motor 8 and the steering cylinder 7.

In some embodiments, the spool of the pilot control valve 3 has a first working position and a second working position, and under the action of the control oil port, the spool of the pilot control valve 3 can also be located between the first working position and the second working position, so as to flexibly adjust the opening degree of the two oil outlets of the pilot control valve 3, and further flexibly distribute the flow rate of the hydraulic oil to different actuators. When the valve core of the hydraulic control valve 3 is located at the first working position, the oil inlet 30 of the hydraulic control valve 3 is communicated with the first oil outlet 31 of the hydraulic control valve 3, and the hydraulic pump 1 independently supplies oil to the traveling motor 8; when the valve core of the hydraulic control valve 3 is located at the second working position, the oil inlet 30 of the hydraulic control valve 3 is communicated with the second oil outlet 32 of the hydraulic control valve 3, and the hydraulic pump 1 independently supplies oil to the steering oil cylinder 7; when the valve core of the hydraulic control valve 3 is located between the first working position and the second working position, the oil inlet 30 of the hydraulic control valve 3 is communicated with the first oil outlet 31 and the second oil outlet 32 of the hydraulic control valve 3, and the hydraulic pump 1 supplies oil to the traveling motor 8 and the steering cylinder 7 simultaneously.

In some embodiments, the control valve group includes a first direction valve 5 disposed between the pilot-controlled valve 3 and the travel motor 8, and the first direction valve 5 is configured to switch the rotation direction of the travel motor 8.

In some embodiments, the pilot valve group includes a second direction change valve 6 disposed between the pilot valve 3 and the steering cylinder 7, and the second direction change valve 6 is configured to switch the moving direction of the movable part of the steering cylinder 7.

In some embodiments, the oil inlet 51 of the first direction valve 5 is connected to the first oil outlet 31 of the pilot-controlled valve 3, the oil outlet 52 of the first direction valve 5 is connected to the oil discharge pipeline, and the first working oil port 53 and the second working oil port 54 of the first direction valve 5 are respectively connected to two working oil ports of the traveling motor 8. The first reversing valve 5 can adopt a three-position four-way electromagnetic reversing valve with an H-shaped middle position function.

In some embodiments, the control oil ports of the pilot control valve 3 include a first control oil port 33 and a second control oil port 34, and a spring is further disposed at one end of the spool of the pilot control valve 3 close to the second control oil port 34. The first control oil port 33 of the pilot control valve 3 is connected with the second oil outlet 32 of the pilot control valve 3. An oil inlet 61 of the second reversing valve 6 is connected with the second oil outlet 32 of the hydraulic control valve 3, an oil outlet 62 of the second reversing valve 6 is connected with an oil discharge pipeline, a first working oil port 63 and a second working oil port 64 of the second reversing valve 6 are respectively connected with two working oil ports of the steering oil cylinder 7, and a feedback oil port 65 of the second reversing valve 6 is connected with the second control oil port 34 of the hydraulic control valve 3.

The walking motor 8 is connected with an oil discharge pipeline through an oil outlet 52 of the first reversing valve 5, and the steering oil cylinder 7 is connected with the oil discharge pipeline through an oil outlet 62 of the second reversing valve 6, so that the pressure superposition phenomenon can be improved.

The second reversing valve 6 has a first working position, a second working position and a third working position, in the first working position of the second reversing valve 6, the first oil cavity of the steering oil cylinder 7 is filled with oil, the oil inlet 61 of the second reversing valve 6 is communicated with the feedback oil port 65, in the second working position of the second reversing valve 6, the second oil cavity of the steering oil cylinder 7 is filled with oil, the oil inlet 61 of the second reversing valve 6 is communicated with the feedback oil port 65, in the third working position of the second reversing valve 6, the steering oil cylinder 7 is stopped, and the oil outlet 62 of the second reversing valve 6 is communicated with the feedback oil port 65. The second reversing valve 6 can be a three-position five-way electromagnetic reversing valve.

The feedback oil path includes an oil path between the feedback oil port 65 of the second direction valve 6 and the second control oil port 34 of the pilot control valve 3. As shown in fig. 2, according to the above configuration, if the vehicle only performs a traveling action, the second direction valve 6 is in the third working position, the hydraulic oil of the second control oil port 34 of the pilot control valve 3 flows back to the oil tank through the feedback oil port 65 and the oil outlet 62 of the second direction valve 6, and at this time, the hydraulic oil acts on the first control oil port 33 of the pilot control valve 3 through the second oil outlet 32 of the pilot control valve 3, so that the spool of the pilot control valve 3 moves to the first working position, and the output flow of the hydraulic pump 1 is all supplied to the traveling motor 8 through the first oil outlet 31 of the pilot control valve 3. If the vehicle needs to do steering action simultaneously in the walking process, the second reversing valve 6 is located at the first working position or the second working position, the second oil outlet 32 of the hydraulic control valve 3 is communicated with the steering oil cylinder 7, hydraulic oil with pressure acts on the second control oil port 34 of the hydraulic control valve 3 through a feedback oil path, so that the valve core of the hydraulic control valve 3 moves from the first working position to one end where the second working position is located until the sum of the pressure and the spring force of the second control oil port 34 is balanced with the pressure of the first control oil port 33, the valve core of the hydraulic control valve 3 is located between the first working position and the second working position at the moment, the second oil outlet 32 of the hydraulic control valve 3 can output hydraulic oil with a certain flow rate to provide power for the steering oil cylinder 7.

In some embodiments, the control valve block comprises a first relief valve 2 to limit the maximum pressure of the entire hydraulic system. An oil inlet of the first overflow valve 2 is connected with an oil outlet of the hydraulic pump 1 and an oil inlet of the hydraulic control valve 3, and an oil outlet of the first overflow valve 2 is connected with an oil discharge pipeline.

In some embodiments, the control valve block comprises a second relief valve 4 to limit the maximum pressure of the feedback oil circuit. An oil inlet of the second overflow valve 4 is connected with the feedback oil path, and an oil outlet of the second overflow valve 4 is connected with the oil discharge pipeline.

In some embodiments, the pilot operated valve 3 may be a static load sensing pressure compensating valve, and the second directional valve 6 may be a three-position five-way electromagnetic directional valve. The static load sensing pressure compensation valve is provided with an oil inlet, two oil outlets, a load sensing oil port and a valve core, and can be used as the oil inlet 30, the first oil outlet 31, the second oil outlet 32, the second control oil port 34 and the valve core of the hydraulic control valve 3 respectively, hydraulic oil introduced into the valve can act on the valve core through one of the two oil outlets to enable the position of the valve core to move, and the effect of an oil path between the first control oil port 33 of the hydraulic control valve 3 and the second oil outlet 32 of the hydraulic control valve 3 is achieved. After oil is fed into an oil inlet of the static load sensing pressure compensation valve, necessary flow can be preferentially provided to an oil outlet connected with the steering oil cylinder 7 without being influenced by load pressure change in a hydraulic system. The remaining part of the output flow of the hydraulic pump 1 is supplied to the traveling motor 8 through an oil outlet connected to the traveling motor 8.

Compared with the method that the flow of the walking oil path and the flow of the steering oil path are distributed by using the pressure compensation flow regulating valve, the feedback oil path is arranged between the static load induction pressure compensation valve and the three-position five-way electromagnetic directional valve, and the method is favorable for distributing the flow for executing the walking action and the steering action more flexibly.

In some embodiments, a throttle valve 9 is provided between the pilot operated valve 3 and the steering cylinder 7 to provide a constant flow to the steering cylinder 7. The oil inlet and the oil outlet of the throttle valve 9 can be respectively connected with the second oil outlet 32 of the hydraulic control valve 3 and the oil inlet 61 of the second reversing valve 6.

Some embodiments of the present disclosure also provide an aerial work platform comprising a chassis and a lift platform.

The chassis comprises the walking steering hydraulic system, a walking mechanism in driving connection with a walking motor 8 of the walking steering hydraulic system and a steering mechanism in driving connection with a steering oil cylinder 7 of the walking steering hydraulic system. The lifting platform is arranged on the chassis and can be a scissor type lifting platform.

Compared with the walking steering hydraulic system shown in fig. 1, the walking steering hydraulic system of the embodiment of the disclosure can improve the pressure superposition phenomenon. On one hand, the hydraulic pump provides corresponding flow output to the walking steering hydraulic system according to the load condition required by the vehicle, so that energy can be saved, and the cruising ability of the aerial work platform of the embodiment of the disclosure can be improved; on the other hand, the problem that the walking motor and the steering oil cylinder have no action due to overhigh pressure of a hydraulic system under the conditions of large walking load and steering requirement can be solved, and the control performance and the safety of the aerial work platform disclosed by the embodiment of the invention are improved, so that the safety of the aerial work platform and operators is protected, and the operation comfort level and the riding comfort level of the aerial work platform are improved.

Finally, it should be noted that: the above examples are intended only to illustrate the technical solutions of the present disclosure and not to limit them; although the present disclosure has been described in detail with reference to preferred embodiments, those of ordinary skill in the art will understand that: modifications to the embodiments of the disclosure or equivalent replacements of parts of the technical features may be made, which are all covered by the technical solution claimed by the disclosure.