阅读说明：本技术 液压系统、液压系统的调整方法以及工程车辆 (Hydraulic system, method for adjusting hydraulic system, and engineering vehicle ) 是由 卿丽纯 郭方云 李红术 徐亮 周清海 于 2020-04-03 设计创作，主要内容包括：本申请公开了一种液压系统、液压系统的调整方法以及工程车辆包括恒压泵组,恒压泵组包括第一溢流阀以及主泵,主泵包括出油口,第一溢流阀用于控制主泵的输出压力；主油路；第一液压单元；包括第二溢流阀、第一执行部件以及第一分配阀组；第二液压单元；包括第二执行部件以及第二分配阀组；第一控制阀；第二溢流阀；以及第三溢流阀,第三溢流阀与主油路连接以用于主油路溢流保护；第二溢流阀的开启压力大于第一溢流阀的开启压力,第三溢流阀的开启压力大于第一溢流阀的开启压力。本申请的液压系统、液压系统的调整方法以及工程车辆,具有安全的优点。(The application discloses a hydraulic system, an adjusting method of the hydraulic system and an engineering vehicle, wherein the engineering vehicle comprises a constant pressure pump set, the constant pressure pump set comprises a first overflow valve and a main pump, the main pump comprises an oil outlet, and the first overflow valve is used for controlling the output pressure of the main pump; a main oil path; a first hydraulic unit; the first overflow valve, the first execution component and the first distribution valve group are included; a second hydraulic unit; the second distribution valve group is arranged on the second executing part; a first control valve; a second overflow valve; the third overflow valve is connected with the main oil way and used for overflow protection of the main oil way; the opening pressure of the second overflow valve is greater than that of the first overflow valve, and the opening pressure of the third overflow valve is greater than that of the first overflow valve. The hydraulic system, the hydraulic system adjusting method and the engineering vehicle have the advantage of safety.)

1. The hydraulic system is characterized by comprising

The constant pressure pump set (1), the constant pressure pump set (1) comprises a first overflow valve (14) and a main pump (11), the main pump (11) comprises an oil outlet (111), and the first overflow valve (14) is used for controlling the output pressure of the main pump (11);

the oil outlet (111) is connected with the main oil way (2);

a first hydraulic unit (3); the first hydraulic unit (3) comprises a second overflow valve (31), a first execution component (32) and a first distribution valve group (33) used for distributing the oil path of the first execution component (32);

a second hydraulic unit (4); the second hydraulic unit (4) comprises a second execution component (41) and a second distribution valve group (42) for distributing an oil path of the second execution component (41);

a first control valve (51), the first control valve (51) connecting the main oil path (2) selectively with the first distribution valve group (33) or the second distribution valve group (42); the second overflow valve (31) is arranged on an oil path between the first distribution valve group (33) and the first control valve (51);

the third overflow valve (6) is connected with the main oil way (2) and used for overflow protection of the main oil way (2);

when the first control valve (51) is in a first working position, the main oil way (2) is communicated with the first distribution valve group (33); when the first control valve (51) is in a second working position, the main oil path (2) is communicated with the second distribution valve group (42);

the opening pressure of the second overflow valve (31) is greater than the opening pressure of the first overflow valve (14), and the opening pressure of the third overflow valve (6) is greater than the opening pressure of the first overflow valve (14).

2. The hydraulic system of claim 1, wherein: the hydraulic system comprises a drain line (8) and a third control valve (53); the third control valve (53) selectively connects the drain line (8), the first spill valve (14), and the main oil passage (2);

the third control valve (53) is in a third working position, and the oil drainage pipeline (8) is communicated with the first overflow valve (14);

the third control valve (53) is located at a fourth working position, and the main oil way (2) is communicated with the first overflow valve (14).

3. The hydraulic system of claim 1, wherein: the hydraulic system comprises an oil return pipeline (81); and the third overflow valve (6) is connected between the main oil way (2) and the oil return pipeline (81).

4. The hydraulic system of claim 3, wherein: the hydraulic system comprises an oil return filter (82) and a radiator (83), wherein the oil return filter (82) and the radiator (83) are sequentially arranged on an oil return pipeline (81).

5. The hydraulic system of claim 1, wherein: the hydraulic system comprises a filter (7), and the filter (7) is arranged on the main oil way (2).

6. The hydraulic system of claim 1, wherein: the hydraulic system comprises an emergency pump (9), and an oil outlet end of the emergency pump (9) and an oil outlet (111) of the main pump (11) are connected in parallel to the main oil way (2).

7. The hydraulic system of claim 6, wherein: the hydraulic system comprises a first check valve (91) and a second check valve (13); the first check valve 91 is arranged between the oil outlet end of the emergency pump (9) and the main oil way (2), and the second check valve (13) is arranged between the oil outlet (111) of the main pump (11) and the main oil way (2).

8. A method of adjusting a hydraulic system according to any one of claims 1 to 7, characterized in that: comprises a first stage, a second stage, a third stage and a fourth stage which are sequentially carried out;

the first stage is as follows:

the pressure of the constant pressure pump set (1) is increased to build pressure in the main oil way (2);

and a second stage:

switching the first control valve (51) to a first working position;

adjusting the opening pressure of the second overflow valve (31) to a third preset pressure;

and a third stage:

switching the first control valve (51) to a second working position;

adjusting the opening pressure of the third overflow valve (6) to a fourth preset pressure;

a fourth stage: adjusting the opening pressure of the first overflow valve (14) to a fifth preset pressure; the fifth preset pressure is less than the fourth preset pressure, and the fifth preset pressure is less than the third preset pressure.

9. The regulation method according to claim 8, characterized in that, in the first phase, the step of increasing the pressure of the constant pressure pump group (1) to build pressure in the main oil circuit (2) comprises in particular:

adjusting the opening pressure of a first overflow valve (14) to the maximum value within the rated range of the first overflow valve (14);

adjusting the opening pressure of a third overflow valve (6) to the maximum value within the rated range of the third overflow valve (6);

starting a main pump (11) to build pressure in a main oil path (2);

the first relief valve (14) is adjusted so that the output pressure of the main pump (11) is increased.

10. The regulation method according to claim 8, characterized in that, in the first phase, the step of increasing the pressure of the constant pressure pump group (1) to build pressure in the main oil circuit (2) comprises in particular:

adjusting the opening pressure of the first overflow valve (14) to be a first preset pressure;

adjusting the opening pressure of the third overflow valve (6) to a second preset pressure;

starting a main pump (11) to build pressure in a main oil path (2);

adjusting the first relief valve (14) such that the output pressure of the main pump (11) increases;

wherein the third preset pressure is less than or equal to the second preset pressure; the fourth preset pressure is less than or equal to the second preset pressure; the third preset pressure is less than or equal to the first preset pressure; the fourth preset pressure is less than or equal to the first preset pressure.

11. The adjustment method according to claim 8, characterized in that: the fourth preset pressure is less than or equal to the third preset pressure.

12. Engineering vehicle, its characterized in that: the work vehicle comprises a vehicle body and a hydraulic system according to any one of claims 1 to 7, which is provided on the vehicle body.

Technical Field

The present disclosure relates to a working vehicle, and more particularly, to a hydraulic system, a method of adjusting the hydraulic system, and a working vehicle.

Background

A constant pressure pump is a pump that keeps the output pressure constant. The flow rate changes with the change of the external resistance. In the system of the constant pressure pump, the flow rate changes along with the change of the external load, the pressure of the system is kept unchanged, and if the resistance of the system is not changed, the constant pressure pump can also provide constant flow rate.

Disclosure of Invention

In view of the above, embodiments of the present disclosure are intended to provide a hydraulic system, a method for adjusting the hydraulic system, and an engineering vehicle, so as to solve the safety problem.

In order to achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:

1. the hydraulic system comprises a constant-pressure pump set, the constant-pressure pump set comprises a first overflow valve and a main pump, the main pump comprises an oil outlet, and the first overflow valve is used for controlling the output pressure of the main pump; the oil outlet is connected with the main oil way; a first hydraulic unit; the first hydraulic unit comprises a second overflow valve, a first execution component and a first distribution valve group used for distributing the oil path of the hydraulic execution component; a second hydraulic unit; the second hydraulic unit comprises a second execution component and a second distribution valve group used for distributing the second execution component oil way; a first control valve selectively connecting the main oil passage with the first distribution valve group or the second distribution valve group; the second overflow valve is arranged on an oil path between the first distribution valve group and the first control valve; the third overflow valve is connected with the main oil way and used for overflow protection of the main oil way; when the first control valve is located at a first working position, the main oil way is communicated with the first distribution valve group; when the first control valve is in a second working position, the main oil way is communicated with the second distribution valve group; the opening pressure of the second overflow valve is greater than that of the first overflow valve, and the opening pressure of the third overflow valve is greater than that of the first overflow valve.

Further, the hydraulic system comprises an oil drain pipeline and a third control valve; the third control valve is selectively connected with the oil drainage pipeline, the first overflow valve and the main oil way; the third control valve is in a third working position, and the oil drainage pipeline is communicated with the first overflow valve; the third control valve is located at a fourth working position, and the main oil way is communicated with the first overflow valve.

Further, the hydraulic system comprises an oil return line; the third overflow valve is connected between the main oil way and the oil return pipeline.

Further, hydraulic system includes oil return filter and radiator, oil return filter and radiator set gradually on the oil return pipeline.

Further, the hydraulic system includes a filter disposed on the main oil line.

Further, the hydraulic system comprises an emergency pump, and an oil outlet end of the emergency pump and an oil outlet of the main pump are connected into the main oil way in parallel.

Further, the hydraulic system comprises a first check valve and a second check valve; the first check valve 91 is arranged between the oil outlet end of the emergency pump and the main oil way, and the second check valve is arranged between the oil outlet end of the main pump and the main oil way.

The method for adjusting the hydraulic system comprises a first stage, a second stage, a third stage and a fourth stage which are sequentially carried out;

the first stage is as follows: increasing the pressure of the constant pressure pump set to build pressure in the main oil way;

and a second stage: switching the first control valve to a first working position; adjusting the opening pressure of the second overflow valve to a third preset pressure;

and a third stage: switching the first control valve to a second working position; adjusting the opening pressure of the third overflow valve to a fourth preset pressure;

a fourth stage: adjusting the opening pressure of the first overflow valve to a fifth preset pressure; the fifth preset pressure is less than the fourth preset pressure, and the fifth preset pressure is less than the third preset pressure.

Further, in the first stage, the step of increasing the pressure of the constant pressure pump group to build up the pressure in the main oil path specifically includes: adjusting the opening pressure of a first overflow valve to the maximum value within the rated range of the first overflow valve; adjusting the opening pressure of a third overflow valve to the maximum value within the rated range of the third overflow valve; starting a main pump to build pressure in a main oil way; the first spill valve is adjusted so that the output pressure of the main pump is increased.

Further, in the first stage, the step of increasing the pressure of the constant pressure pump group to build up the pressure in the main oil path specifically includes: adjusting the opening pressure of the first overflow valve to be a first preset pressure; adjusting the opening pressure of the third overflow valve to a second preset pressure; starting a main pump to build pressure in a main oil way; adjusting the first overflow valve to increase the output pressure of the main pump; wherein the third preset pressure is less than or equal to the second preset pressure; the fourth preset pressure is less than or equal to the second preset pressure; the third preset pressure is less than or equal to the first preset pressure; the fourth preset pressure is less than or equal to the first preset pressure.

Further, the fourth preset pressure is less than or equal to the third preset pressure.

A working vehicle comprises a vehicle body and any one of the hydraulic systems, wherein the hydraulic system is arranged on the vehicle body.

The hydraulic system, the adjustment method of the hydraulic system and the engineering vehicle provided by the embodiment of the application are characterized in that a constant-pressure pump set, a second overflow valve and a third overflow valve are arranged, the constant-pressure pump set comprises a first overflow valve and a main pump, the first overflow valve is used for controlling the output pressure of the main pump, the opening pressure of the second overflow valve is set to be larger than the opening pressure of the first overflow valve, and the opening pressure of the third overflow valve is larger than the opening pressure of the first overflow valve, so that the hydraulic system can be maintained under the preset opening pressure of a first hydraulic unit, the main pump can be effectively prevented from being heated, heated and wearing a pump body, and the service life of the main; and under the condition of sudden change of external load, the first hydraulic unit and the second hydraulic unit are respectively protected through the additionally arranged second overflow valve and the additionally arranged third overflow valve, so that the safety of the whole hydraulic system is ensured.

Drawings

FIG. 1 is a schematic structural diagram of a hydraulic system according to an embodiment of the present disclosure;

FIG. 2 is an enlarged view of area A of FIG. 1;

FIG. 3 is a flowchart of an adjustment method according to an embodiment of the present application;

FIG. 4 is a flow chart of an adjustment method according to another embodiment of the present application;

fig. 5 is a flowchart of an adjustment method according to another embodiment of the present application.

Detailed Description

It should be noted that, in the case of conflict, the technical features in the examples and examples of the present application may be combined with each other, and the detailed description in the specific embodiments should be interpreted as an explanation of the present application and should not be construed as an improper limitation of the present application.

In the description of the embodiments of the present application, the "up", "down", "left", "right", "front", "back" orientation or positional relationship is based on the orientation or positional relationship shown in fig. 1, it is to be understood that these orientation terms are merely for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be considered as limiting the present application.

As shown in fig. 1 and 2, a hydraulic system includes a constant pressure pump group 1, a main oil passage 2, a first hydraulic unit 3, a second hydraulic unit 4, a first control valve 51, and a third relief valve 6.

The constant pressure pump set 1 comprises a first overflow valve 14 and a main pump 11, the main pump 11 can be a plunger pump, the first overflow valve 14 can be a pump set manufacturer, the first overflow valve 14 is used for controlling output pressure of the main pump 11, and specifically, the output pressure of the constant pressure pump set 1 is adjusted by setting opening pressure of the first overflow valve 14.

In this embodiment, the constant pressure pump set 1 includes a control valve 15, the main pump 11 includes a first plunger cylinder (not shown) and a second plunger cylinder (not shown), a first oil port (not shown) of the control valve 15 is connected to the first plunger cylinder through a first throttle (not shown), the first oil port of the control valve 15 is connected to a first end and a second end of the first overflow valve 14 through a second throttle (not shown), the first oil port of the control valve 15 is connected to a second oil port (not shown) of the control valve 15, the first end of the first overflow valve 14 is connected to an oil tank (not shown), the second end of the first overflow valve 14 is connected to a first control end (not shown) of the control valve 15, a third oil port (not shown) of the control valve 15 is connected to a second control end (not shown) of the control valve 15, and the second control end of the control valve 15 is connected to the second plunger cylinder through a third oil port (not shown).

It can be understood that the constant pressure pump unit 1 may have different structures according to different models and different applications, and it is only necessary to ensure the constant pressure function and to realize the function of adjusting the output pressure of the constant pressure pump unit 1 by setting the opening pressure of the first relief valve 14.

The main pump 11 includes an oil inlet 112 and an oil outlet 111; the oil outlet 111 is connected with the main oil path 2; the oil inlet 112 is connected to the oil tank.

The first hydraulic unit 3 includes a second relief valve 31, a first actuator 32, and a first distribution valve group 33 for distributing an oil path of the first actuator 32. Taking a common boom in an engineering vehicle as an example, the first executing component 32 may be one or more of a rotary cylinder, a luffing cylinder and a telescopic cylinder, and a plurality of distribution valves in the first distribution valve group 33 start the first executing component 32 as required, so as to complete the functions of rotation, luffing and telescoping of the boom.

The second hydraulic unit 4 includes a second actuator 41 and a second distribution valve group 42 for distributing an oil passage of the second actuator 41. Taking a support leg commonly found in a work vehicle as an example, the second actuating component 41 may be one or more of a vertical telescopic cylinder and a horizontal telescopic cylinder, and the plurality of distribution valves in the second distribution valve group 42 activate the second actuating component 41 as required, so as to complete the extension and support functions of the support leg, and provide a stable support for the work vehicle to perform work.

The first control valve 51 selectively connects the main oil passage 2 with the first distribution valve group 33 or the second distribution valve group 42. When the first control valve 51 is in the first working position, the main oil path 2 is communicated with the first distribution valve group 33, an oil path (not shown) between the first distribution valve group 33 and the first control valve 51 is protected by the second overflow valve 31, and the second hydraulic unit 4 is in a pressure relief state; when the first control valve 51 is in the second working position, the main oil path 2 communicates with the second distribution valve group 42; the third overflow valve 6 performs overflow protection on the main oil passage 2, and the first hydraulic unit 3 releases pressure.

The second overflow valve 31 is arranged on an oil path between the first distribution valve group 33 and the first control valve 51, when the main oil path 2 is communicated with the first distribution valve group 33, the external load born by the first hydraulic unit 3 suddenly changes, and the balance cannot be rapidly carried out through the constant pressure pump group 1, the hydraulic pressure in the oil path can rapidly rise to reach a preset value, therefore, the second overflow valve 31 is opened to communicate the oil path with an oil tank, and the overpressure hydraulic oil returns to the oil tank, so that the overflow safety function is completed, and the situations of pipe burst and the like are avoided.

Similarly, the third overflow valve 6 is connected with the main oil way 2 and used for overflow protection of the main oil way 2; when the main oil path 2 is communicated with the second distribution valve group 42, and the external load borne by the second hydraulic unit 43 suddenly changes suddenly, so that the external load cannot be quickly balanced by the constant pressure pump group 1, the hydraulic pressure in the main oil path 2 rapidly rises to reach a preset value, and therefore, the second overflow valve 31 is opened to communicate the main oil path 2 with the oil tank, and the overpressure hydraulic oil returns to the oil tank.

It is understood that the external load may be the weight of the construction vehicle itself, or the weight of people or goods etc. borne thereby.

It should be noted that, in the hydraulic field, a hydraulic system using a constant pressure pump can achieve a large discharge flow rate and increase a reaction rate under a low load condition and a small discharge flow rate and ensure a pressure in the system under a high load condition due to a self-regulation function. Compared with a hydraulic system adopting a conventional hydraulic pump, the hydraulic system adopting the constant pressure pump has the advantages of energy conservation and small system pressure fluctuation. In the process that the relief valve sets the opening pressure of the preset value, the pressure in the hydraulic system needs to be increased to the preset value or above, then the pressure gauge and the relief valve are connected, and the relief valve is adjusted until the pressure gauge displays that the pressure in the hydraulic system reaches the preset value. And because the pressure of the constant pressure pump can be adjusted, once other overflow valves are connected into the hydraulic system, the situation that the hydraulic system cannot reach the set value of the constant pressure pump can be found, and the set value is maintained at the preset opening pressure of the overflow valves, namely, the effect of the constant pressure pump is lost, and because the pressure in the hydraulic system does not reach the standard, the constant pressure pump always does work in full force, so that the heat is generated, the heat is scalded, and the service life of a pump body is influenced due to abrasion. Therefore, a hydraulic system that normally uses a constant pressure pump is not provided with a relief valve alone.

In the embodiment of the present application, the opening pressure of the second overflow valve 31 is greater than the opening pressure of the first overflow valve 14, and the opening pressure of the third overflow valve 6 is greater than the opening pressure of the first overflow valve 14, so that the hydraulic system can be maintained under the preset opening pressure of the first overflow valve 14, thereby preventing the main pump 11 from generating heat, being hot and wearing the pump body, and further ensuring the service life of the main pump 11, under the condition of sudden change of external load, the first hydraulic unit 3 and the second hydraulic unit 4 are respectively protected through the additionally installed second overflow valve 31 and the third overflow valve 6, and the safety of the whole hydraulic system is ensured.

The adjustment method of the hydraulic system, as shown in fig. 1 to 5, includes a first stage, a second stage, a third stage and a fourth stage which are performed in sequence;

the first stage is as follows:

and S10, increasing the pressure of the constant pressure pump set 1 to build pressure in the main oil circuit 2. The pressure of the constant pressure pump group 1 should be increased to be greater than or equal to the third preset pressure and the fourth preset pressure, which are preset subsequently, so as to facilitate the adjustment of the second overflow valve 31 and the third overflow valve 6 in the subsequent steps.

And a second stage:

s20, switching the first control valve 51 to a first working position; the main oil path 2 is communicated with the first distribution valve group 33, and the hydraulic oil provided by the constant pressure pump group 1 enters the first execution component 32 through the main oil path 2 and the first distribution valve group 33; the first actuator 32 may be closed to create a pressure hold, facilitating adjustment of the second relief valve 31.

S21, adjusting the opening pressure of the second overflow valve 31 to a third preset pressure; the third preset pressure is the preset opening pressure of the second relief valve 31.

And a third stage:

s30, switching the first control valve 51 to a second working position; the main oil path 2 is communicated with the second distribution valve group 42, and the hydraulic oil supplied by the constant pressure pump group 1 enters the second execution part 41 through the main oil path 2 and the second distribution valve group 42; the second actuator 41 may be actuated to close to create a pressure build-up, facilitating adjustment of the third relief valve 6.

S31, adjusting the opening pressure of the third overflow valve 6 to a fourth preset pressure; the fourth preset pressure is the preset opening pressure of the third overflow valve 6.

It can be understood that the second and third relief valves 31 and 6 in the second or third stage may be adjusted by accessing the pressure gauge while adjusting the relief valves and observing the pressure gauge.

A fourth stage:

s40, adjusting the opening pressure of the first overflow valve 14 to a fifth preset pressure; the fifth preset pressure is less than the fourth preset pressure, and the fifth preset pressure is less than the third preset pressure. The fifth preset pressure is the preset opening pressure of the first overflow valve 14 and is also the output pressure of the constant pressure pump group 1.

In one possible embodiment, as shown in fig. 1 and 2, the hydraulic system comprises a drain line 8 and a third control valve 53; the third control valve 53 selectively connects the drain line 8, the first spill valve 14, and the main oil passage 2; the third control valve 53 is in a third working position, the oil drainage pipeline 8 is communicated with the first overflow valve 14, and the constant pressure pump set 1 has no output pressure, so that the hydraulic oil output of the constant pressure pump set 1 can be conveniently stopped in an emergency state; the third control valve 53 is in the fourth operating position, and the main oil path 2 is communicated with the first overflow valve 14, so that the pressure build-up of the constant pressure pump group 1 in the main oil path 2 is facilitated.

In one possible embodiment, as shown in fig. 1 and 2, the hydraulic system comprises a return line 81; the third overflow valve 6 is connected between the main oil path 2 and the oil return pipeline 81, and when the hydraulic pressure of the main oil path 2 exceeds the opening pressure of the third overflow valve 6, the overpressure hydraulic oil can be returned to the oil tank, so that the overflow safety function is completed, and the situations of pipe explosion and the like are avoided.

As shown in fig. 1 and 2, the hydraulic system includes an oil return filter 82 and a radiator 83, and the oil return filter 82 and the radiator 83 are sequentially disposed on the oil return pipeline 81, so that on one hand, impurities contained in the hydraulic oil returned to the oil tank can be filtered, on the other hand, the hydraulic oil returned to the oil tank can be cooled, and the hydraulic system can be prevented from being scalded; on the other hand, a certain back pressure can be formed by the filter 82 and the radiator 83, so that the first execution component 32 and/or the second execution component 41 can be prevented from rapidly returning to cause collision under the condition of no back pressure.

In one possible embodiment, as shown in fig. 1 and 2, the hydraulic system includes a filter 7, and the filter 7 is disposed on the main oil path 2 to filter hydraulic oil output from the main pump 11, so as to maintain the cleanliness of hydraulic oil in the system, improve the stability of the hydraulic system, and prolong the service life of corresponding equipment.

In one possible embodiment, as shown in fig. 1 and 2, the hydraulic system comprises an emergency pump 9, and an oil outlet end (not shown) of the emergency pump 9 is connected in parallel with an oil outlet 111 of the main pump 11 into the main oil passage 2.

In one possible embodiment, as shown in fig. 1 and 2, the hydraulic system comprises a first non-return valve 91; a first check valve 91 is provided between the outlet end of the emergency pump 9 and the main oil passage 2 to prevent the reverse flow of the hydraulic oil into the emergency pump 9.

In a possible embodiment, as shown in fig. 1 and 2, the hydraulic system comprises a second non-return valve 13; the second check valve 13 is arranged between an oil outlet 111 of the main pump 11 and the main oil path 2 to prevent the hydraulic oil from reversely flowing into the constant pressure pump set 1; in addition, by providing the second check valve 13, when the external load borne by the first hydraulic unit 3 and/or the second hydraulic unit 43 increases suddenly, the second check valve 13 is closed, and the hydraulic system adjusts the pressure in the oil passage by the second relief valve 31 and the third relief valve 6, thereby completing the relief safety function and avoiding the occurrence of pipe burst and the like.

One possible implementation manner, as shown in fig. 1 to 4, in the first stage, the step S10 specifically includes:

and S11, adjusting the opening pressure of the first overflow valve 14 to the maximum value within the rated range of the first overflow valve 14.

And S12, adjusting the opening pressure of the third overflow valve 6 to the maximum value within the rated range of the third overflow valve 6.

It is understood that the step S11 and the step S12 have no logical relationship in sequence, and may be executed first in step S11 or first in step S12. In addition, the rated range is generally calibrated by a manufacturer of the relief valve, and for the screw type relief valve, the maximum value of the rated range is obtained by selecting the screw clockwise or anticlockwise.

S13, the main pump 11 is started to build pressure in the main oil passage 2.

S14, the first spill valve 14 is adjusted so that the output pressure of the main pump 11 increases. The output pressure should be greater than or equal to the third preset pressure and the fourth preset pressure preset subsequently, so as to facilitate the adjustment of the second relief valve 31 and the third relief valve 6 in the subsequent steps.

It is understood that, the logical relationship between the step S13 and the step S14 is not adjusted in sequence, and the step S13 or the step S14 may be performed first.

One possible implementation manner, as shown in fig. 1 to 3 and 5, in the first stage, the step S10 specifically includes:

and S15, adjusting the opening pressure of the first overflow valve 14 to be a first preset pressure. Wherein the third preset pressure is less than or equal to the first preset pressure; the fourth preset pressure is less than or equal to the first preset pressure, so that the adjustment is convenient.

And S16, adjusting the opening pressure of the third overflow valve 6 to a second preset pressure. Wherein the third preset pressure is less than or equal to the second preset pressure; the fourth preset pressure is less than or equal to the second preset pressure.

It is understood that the step S15 and the step S16 have no logical relationship in sequence, and may be executed first in step S15 or first in step S16.

S17, the main pump 11 is started to build pressure in the main oil passage 2.

S18, the first spill valve 14 is adjusted so that the output pressure of the main pump 11 increases. The output pressure should be greater than or equal to the third preset pressure and the fourth preset pressure preset subsequently, so as to facilitate the adjustment of the second relief valve 31 and the third relief valve 6 in the subsequent steps.

It is understood that, the logical relationship between the step S13 and the step S14 is not adjusted in sequence, and the step S13 or the step S14 may be performed first.

In a possible embodiment, the fourth preset pressure is less than or equal to the third preset pressure. Specifically, the first preset pressure may be 350-400 bar; the second preset pressure is 350-400 bar; the third preset pressure is 280-350 bar; the fourth preset pressure is 260-300 bar; the fifth preset pressure is 200-250 bar.

An engineering vehicle comprises a vehicle body and any one of the hydraulic systems, wherein the hydraulic system is arranged on the vehicle body to complete various functions.

The various embodiments/implementations provided herein may be combined with each other without contradiction.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.