WO2014000386A1

WO2014000386A1 - Hydraulic system, control method for hydraulic system and engineering machinery therewith

Info

Publication number: WO2014000386A1
Application number: PCT/CN2012/086101
Authority: WO
Inventors: 李沛林; 王佳茜; 王巧云
Original assignee: 中联重科股份有限公司
Priority date: 2012-06-26
Filing date: 2012-12-07
Publication date: 2014-01-03
Also published as: CN102720710A; CN102720710B

Abstract

Disclosed is a control method for a hydraulic system. The hydraulic system comprises a variable delivery pump (1) and a plurality of actuating mechanisms (2) driven by the variable delivery pump (1), wherein each of said plurality of actuating mechanisms (2) is in separate communication with the variable delivery pump (1) via hydraulic branches arranged in a parallel connection; a flow control valve (3) for adjusting the flow rate of the respective actuating mechanism is provided on each hydraulic branch between the actuating mechanism (2) and the variable delivery pump (1). The control method comprises: calculating a required flow rate of the actuating mechanism (2) according to the operating speed of the actuating mechanism (2); adjusting the displacement of the variable delivery pump (1) such that an output flow rate thereof is equal to the sum of the required flow rates of the actuating mechanisms; and adjusting each of the flow control valves (3) such that the sum of the set flow rates thereof is equal to or greater than the output flow rate of the variable delivery pump (1). Further disclosed are a hydraulic system and engineering machinery having the hydraulic system. With the hydraulic system and the control method thereof, the possibility of overflow occurring in the system can be effectively reduced while the power loss of the system can also be reduced, because it is not necessary to set a pressure difference within the system.

Description

Hydraulic system, hydraulic system control method and construction machinery

Technical field

The present invention relates to the field of hydraulics, and in particular to a control method of a hydraulic system, a hydraulic system using the same, and a construction machine using the hydraulic system. Background technique

In modern construction machinery, hydraulic systems in which a plurality of actuators are driven by a single pump are often used. For example, in a pump truck, a distributor, etc., a hydraulic system in which a plurality of actuators are driven by a single pump is used. In the prior art, in order to save energy, that is, the flow in the system does not occur or the overflow phenomenon occurs. These single-pump, multi-actuator hydraulic systems typically use load-sensing technology, the most common of which is the use of variable pumps and load-sensitivity, which is becoming more widely used.

Specifically, as shown in FIG. 1, the hydraulic system includes a variable pump 1, a load sensitive width 6, an overflow width 7, and a plurality of actuators 2, wherein each actuator 2 passes through a parallel hydraulic branch and a variable pump 1 Connected, wherein each of the hydraulic branch roads is provided with a series throttle width 31 and a constant pressure relief width 32, which is formed to adjust the speed of the actuator 2, wherein the differential pressure reduction width is 32 The pressure difference between the inlet and the outlet of the throttle block 31 is kept constant, and the flow rate of each hydraulic branch is controlled by controlling the wide opening of the throttle width 31 to ensure the simultaneous operation of the plurality of actuators 2. In addition, the overflow is 7 to ensure the safety of the overall system. When the system pressure is greater than the set pressure of the overflow width 7, the excess flow flows back to the tank through the overflow.

In order to realize the above load-sensing technology, a shuttle flange 41 communicating with each other is disposed between adjacent hydraulic branches, and the maximum load pressure of each actuator 2 can be selected by the plurality of shuttles 41, and the maximum load is selected. Pressure feedback is sensitive to load 6 . Wherein, the load sensitive width 6 can compare the maximum load pressure of the actuator 2 with the pressure of the variable pump 1 outlet, and if the pressure difference exceeds the set value of the load sensitivity, the output flow of the variable pump 1 is too large. Load sensitive The sense width 6 can control the displacement of the variable pump 1 to be reduced so that the above pressure difference is restored to the set value. In addition, when the pressure difference is lower than the set value of the load sensitivity width 6, it indicates that the output flow rate of the variable pump 1 is too small, and at this time, the load sensitivity width 6 can also increase the displacement of the variable pump 1 and make the pressure The difference returns to the set value. Thereby, the variable pump 1 is required to output only the required flow rates of the plurality of actuators 2. And reduce the problem of system traffic overflow.

However, the above load-sensing technology also has certain drawbacks, that is, in order to realize the work of load-sensitivity, it is necessary to set a set pressure difference in the load-sensitivity wide 6 , and in the above work, even if the pressure difference of the system is restored to the set Constant pressure difference, this set differential pressure will inevitably bring some extra power loss to the system.

Therefore, it is of positive significance to provide a hydraulic system and a control method thereof that better reduce system power loss. Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a control method for a hydraulic system which can effectively reduce the possibility of overflow of the system and effectively reduce the power loss of the system.

Another object of the present invention is to provide a hydraulic system capable of effectively reducing the possibility of overflow of the system and effectively reducing the power loss of the system.

It is still another object of the present invention to provide a construction machine using the hydraulic system provided by the present invention.

In order to achieve the above object, according to an aspect of the present invention, a control method of a hydraulic system including a variable pump and a plurality of actuators driven by the variable pump, the plurality of actuators being respectively disposed in parallel by a plurality of actuators is provided a hydraulic branch is connected to the variable pump, and the hydraulic branch between each actuator and the variable pump is provided with a flow control width for adjusting a corresponding actuator flow, wherein the control method includes : calculating a required flow rate of the actuator according to the working speed of each of the actuators; adjusting a displacement of the variable pump such that an output flow of the variable pump is equal to a sum of the required flows; and adjusting each Flow control Preferably, when only one of the plurality of actuators operates, the corresponding set flow rate of the flow control is adjusted to be maximum.

Preferably, when at least two actuators work at the same time and need to stop the operation of a part of the actuator, first closing the corresponding flow control width and adjusting the displacement of the variable pump, so that the variable pump The output flow is equal to the sum of the demand flows of the still operating actuators.

Preferably, the speed control is used as the flow control width, and the speed regulation wide design has a throttle width and a fixed pressure reduction width, and the first limit of the throttle inlet and the outlet is maintained by using the fixed pressure reduction width. The pressure difference does not change.

Preferably, the sum of the set flow rates is set to be 105% to 115% of the output flow rate.

Preferably, the hydraulic system further includes a differential pressure detecting module, the control method comprising detecting the second pressure between the highest load pressure of the plurality of actuators and the variable pump outlet pressure using the differential pressure detecting module Poor, when the second pressure difference is greater than a set pressure of the differential pressure reduction corresponding to the actuator having the highest load pressure, reducing an output flow of the variable pump, or increasing the The flow control sets a wide set flow rate such that the second pressure difference is less than or equal to a set pressure of the fixed differential pressure.

Preferably, in the differential pressure detecting module, a shuttle is disposed between two adjacent hydraulic branches, and the shuttles are connected in series to each other to introduce a highest load pressure among the plurality of actuators a differential pressure switch connected to the shuttle, thereby obtaining the second pressure by the differential pressure switch

.

Preferably, a proportional ratio is set in the hydraulic system, and when the second pressure difference is greater than the set pressure of the proportional width, the oil outputted by the variable pump is partially leaked into the oil tank by the proportional width. So that the second pressure difference is less than or equal to the set pressure of the ratio.

Preferably, the ratio is broadly designed with a control cavity, an oil inlet port and a oil return port, and one end of the control cavity is connected to the outlet pressure of the variable pump, and the other end is connected to the differential pressure detecting module. The oil inlet is communicated with an outlet of the variable pump, and the oil return port is in communication with the fuel tank. According to another aspect of the present invention, there is provided a hydraulic system including a variable pump and a plurality of actuators driven by the variable pump, the plurality of actuators being respectively coupled to the hydraulic branch by a plurality of hydraulic branches arranged in parallel a variable pump is connected, and a flow control for adjusting a corresponding actuator flow is provided on the hydraulic branch between each actuator and the variable pump, wherein the hydraulic system further includes a controller, the controller The required flow rate of the actuator is calculated according to the working speed of each of the actuators, wherein the controller can: adjust the displacement of the variable pump such that the output flow of the variable pump is equal to a sum of the demand flow values; and adjusting each of the flow control widths such that a sum of the flow control wide set flows is equal to or greater than an output flow of the variable pump.

Preferably, the flow control is broadly variable, and the speed regulation includes a throttle width and a differential pressure reduction in series, and the differential pressure is widely used to maintain the throttle inlet and outlet. Preferably, the sum of the set flows is between 105% and 115% of the output flow.

Preferably, the hydraulic system further includes a differential pressure detecting module, configured to detect a second pressure difference between a highest load pressure of the plurality of actuators and the variable pump outlet pressure, when The controller is capable of controlling to decrease the output flow of the variable pump, or to increase when the second pressure difference is greater than a set pressure of the differential pressure reduction corresponding to the actuator having the highest load pressure The flow rate controls a set flow rate such that the second pressure difference is less than or equal to a set pressure of the differential pressure reduction.

Preferably, the differential pressure detecting module includes a shuttle sleeve disposed between two adjacent hydraulic branches and a differential pressure switch connected to the shuttle, the shuttles being connected in series to each other to perform the plurality of executions The highest load pressure in the mechanism is introduced into the differential pressure switch such that the second differential pressure is obtained by the differential pressure switch.

Preferably, the hydraulic system further includes a proportional width having a set pressure, and when the second pressure difference is greater than the set pressure of the proportional width, the ratio is wider than the oil portion output by the variable pump The ground is drained into the oil tank such that the second pressure difference is less than or equal to the set pressure of the proportional width.

Preferably, the ratio includes a control chamber, an oil inlet port and a oil return port, wherein one end of the control chamber communicates with an outlet pressure of the variable pump, and the other end communicates with the differential pressure detecting module, the oil inlet port and the oil inlet port The outlet of the variable pump is in communication, and the oil return port is in communication with the oil tank.

According to still another aspect of the present invention, a construction machine is provided, wherein the construction machine includes a hydraulic system provided by the present invention.

According to the above technical solution, since the hydraulic system and the control method thereof provided by the present invention do not need to provide a pressure difference in the system, the possibility of overflow of the system can be effectively reduced, so that the power loss of the system can be effectively reduced, and the utility is strong.

Other features and advantages of the invention will be described in detail in the detailed description which follows. DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are in the In the drawing:

1 is a schematic diagram of a hydraulic system of a single pump multiple actuator in the prior art;

2 is a schematic diagram of a hydraulic system of a single pump multiple actuator according to a first embodiment of the present invention;

3 is a schematic diagram of a hydraulic system of a single pump multiple actuator provided by a second embodiment of the present invention;

Fig. 4 is a schematic view showing a hydraulic system of a single pump multi-actuator according to a third embodiment of the present invention. Description of the reference numerals

1 variable pump 2 actuator 3 flow control wide 4 differential pressure detection module

5 Proportionally wide 6 Load sensitive

7 overflow wide

11 Displacement control device 31

32 differential decompression wide 41

42 differential pressure switch

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are intended to be illustrative and not restrictive.

It should be noted that, unless otherwise stated, the term "output flow rate" used in the present invention is the flow rate value of the variable pump 1 in real time, and the "maximum flow rate" is when the variable pump 1 is operating at full load. The maximum flow value output; and "demand flow" refers to the flow value required by the working organization to achieve a specific working speed. In addition, "set flow rate" and "set pressure" refer to the target value set by the corresponding component for achieving a certain purpose.

As shown in FIG. 2 to FIG. 4, the present invention provides a hydraulic system including a variable pump 1 and a plurality of actuators 2 (cylinders) driven by the variable pump 1, and the plurality of actuators 2 respectively pass A hydraulic branch arranged in parallel is connected to the variable pump 1 for the purpose of driving a multi-actuator by a single pump. In order to ensure that the plurality of actuators 2 work simultaneously, a flow control width 3 for adjusting the flow rate of the corresponding actuator 2 is provided on the hydraulic branch between each actuator 2 and the variable pump 1. Preferably, the flow control width is 3, and the speed limit includes a throttle width 31 and a constant pressure reduction width 32 which are arranged in series, and the differential pressure reduction width 32 maintains a throttle width 31 inlet and outlet. The pressure difference remains unchanged to adjust the flow rate of each hydraulic branch by adjusting the valve opening of the throttle valve 31, thereby ensuring that the plurality of actuators 2 can obtain the required flow rate. In addition, the flow control width 3 can also be other types of hydraulic widening that are considered by those skilled in the art. No restrictions.

In order to achieve the object of the present invention, the present invention provides a control method based on the hydraulic system provided by the present invention, the control method comprising: first calculating the demand flow rate of the actuator 2 according to the operating speed of each actuator 2 . The operating speed of each of the actuators 2 depends on the type of work that the actuator 2 needs to perform, and the speed of the work is achieved by the flow rate of the hydraulic oil. After obtaining the required flow rate of the corresponding actuator 2, the displacement of the variable pump 1 is adjusted so that the output flow of the variable pump 1 is equal to the sum of the required flow rates; and each flow control width is adjusted to 3, so that the set flow rate of the flow control width is 3 The sum is equal to or greater than the output flow of the variable pump 1.

Through the above two adjustment steps, first, the output flow of the variable pump 1 can be used to drive the actuator 2, thereby effectively reducing the possibility of overflow of the system, and the sum of the set flow rates of the flow control width 3 is equal to or greater than The output flow of the variable pump 1 can effectively reduce the pressure loss caused by the throttle control or the speed regulation after the flow control is controlled. Most importantly, the hydraulic system and the control method thereof provided by the invention need not be A set pressure difference is set in the system, so that the power loss caused by setting a set pressure difference in the system in the prior art is avoided, so the utility is strong.

In order to realize the above control method, a controller is provided in the provided hydraulic system, and the controller may preferably be a PLC controller which is common in the art, and the flow control is broadly controlled to be electrically controlled, and the displacement of the variable displacement pump 1 is set. The displacement control device 11, the displacement control device 11 can be a device known to those skilled in the art capable of controlling the displacement of the variable pump, for example, by controlling the electro-hydraulic proportionality, or directly using the electronically controlled pump as the variable pump 1 The controller is provided with the required flow rate of the actuator 2 according to the working speed of each actuator 2, wherein the calculation step of the demand flow can also be calculated by the controller itself, and the operator only needs to input The speed of the corresponding actuator can be. The controller can adjust the displacement of the variable pump 1 by controlling the displacement control device 11 through the sum of the required flow rates of the obtained actuators, and directly control the electronically controlled flow control width, for example, the opening degree of the throttle width 31, Thereby achieving the above object.

Wherein, the sum of the set flow rates of the flow control width mentioned in the present invention is equal to or greater than In the concept of the output flow rate of the variable pump 1, preferably, the sum of the set flow rates is 105% to 115% of the output flow rate. It is preferable that the sum of the set flow rates is slightly larger than the output flow rate for better Avoid the power loss of the output flow when the flow control is wide 3. And slightly larger than the output flow can effectively reduce the error caused by the flow control width 3 and the variable accuracy of the variable pump 1. This error is due to the flow control width. The variable pump 1 has hysteresis, or is caused by a change in parameters such as temperature. Because if there is an error due to the accuracy of the control, if only the sum of the set flow rates of the flow control is set equal to the output flow of the variable pump, it will cause The controlled flow rate of the flow control width 3 is smaller than the output flow rate of the variable pump 1, which causes the system to overflow. This is disadvantageous for achieving the object of the present invention.

On the basis of the above control method, according to different situations, the concept according to the present invention can produce corresponding advantageous effects. The following article will explain several possible situations.

First, in the hydraulic system in which the present invention provides a single pump to drive a plurality of actuators, when only one of the plurality of actuators 2 is operated, it is necessary to pass the work of the one actuator 2 under the concept of the present invention. Speed, calculate the demand flow, and then according to the demand flow, adjust the output flow of the variable pump 1 equal to the demand flow, and at the same time, since only one actuator works, only the corresponding flow control width 3 setting flow adjustment To maximize the value, that is, the opening of the throttling mouth of the flow control width 3 is adjusted to the maximum by the controller. Wherein, if the maximum set flow rate of the flow control width 3 is greater than the output flow rate of the variable pump 1 , since the output flow rate of the variable pump 1 only needs to be supplied to the one actuator, the flow control is not required at this time for flow control. Therefore, it is possible to prevent the system from overflowing, and the object of the present invention can be achieved because power loss is not caused. On the other hand, if the maximum set flow rate of the flow control width 3 is smaller than the output flow rate of the variable pump 1, the system overflow can be minimized by maximizing the set flow rate of the flow control width 3, which is also the present invention. The idea is in line with it.

Then, in the hydraulic system in which the present invention provides a single pump to drive a plurality of actuators, when at least two actuators 2 are operated simultaneously, under normal operating conditions, and the maximum flow of the variable pump 1 is generally greater than that at the same time. The sum of the demand flows of the actuator 2, according to the present invention Conceiving, the displacement of the variable pump 1 is adjusted by the controller and the displacement control device, so that the output flow of the variable pump 1 is equal to the sum of the required flow rates of the actuators 2 operating at the same time; and each corresponding flow control is adjusted by the controller. The width 3 is such that the sum of the set flow rates of the flow control width 3 is equal to or greater than the output flow rate of the variable pump 1.

In the abnormal state, for example, when there is a problem such as an actuator overload, that is, when the maximum flow rate of the variable pump 1 is smaller than the sum of the required flow rates of the actuators 2 operating at the same time, although the maximum flow rate of the variable pump cannot be set equal to or More than the sum of the demand flow of the actuator 2, however, in order to drive the actuator 2 that works at the same time, the displacement of the variable pump 1 can be maximized by the displacement of the controller and the variable pump 1; Each flow control corresponding to the adjustment of the flow is controlled to be 3, so that the sum of the set flow rates of the flow control width 3 is equal to or greater than the maximum output flow rate of the variable pump 1. Thus, while the variable pump 1 is maximally driving the actuator 2 that operates at the same time, the power loss when the output flow rate is controlled by the flow rate can be effectively reduced.

On the basis of the above two cases, if the sum of the demand flows of the actuators 2 operating at the same time is greater than the abnormal state of the sum of the maximum set flows of the corresponding flow control widths 3, when the variable pump 1 output flow is required to be equal When the demand flow of the actuator 2 working at the same time is the same, there is a case where the set flow rate of the variable flow control cannot be adjusted to be equal to or greater than the maximum flow output of the variable pump 1 at this time, in order to minimize the output flow through the flow control For the power loss at a width of 3, preferably, the set flow rate of the flow control width 3 is first adjusted to the maximum, and the displacement of the variable pump 1 is adjusted by the controller and the displacement control device 11, so that the output flow of the variable pump 1 is equal to Or the sum of the set flow rates smaller than the flow control width 3, that is, the sum of the set flow rates of the flow control width 3 is equal to or greater than the output flow rate of the variable pump 1. This minimizes the power loss of the flow.

In addition, when it is necessary to stop the operation of some of the actuators 2, the flow control width corresponding to the portion of the actuator 2 that needs to be stopped is first turned off by the controller, that is, the throttle width 31 is cut off. And the displacement of the variable pump 1 is adjusted by the controller and the displacement control device 11, so that the output flow rate of the variable pump 1 is equal to the sum of the required flow rates of the actuator 2 still operating, such that Can effectively reduce the possibility of system overflow. At the same time, preferably, the controller can determine whether the sum of the set flow rates of the flow control width 3 corresponding to the actuator 2 still working is still the same as the output flow of the variable pump 1, if different, only the corresponding controller The sum of the set flow rates of the flow control width is adjusted to be equal to or greater than the output flow rate of the variable pump 1. At this time, it is possible to effectively reduce the output power and control the power loss through the corresponding flow rate.

Several of the frequently occurring situations are described above, and variations made by those skilled in the art, among other things not mentioned, fall within the scope of the present invention.

Since the above control method may still have system overflow and flow loss through the flow control in some cases, in order to minimize the impact of system overflow, it is necessary to find out that the system flow is too large. Therefore, it is further preferred that the hydraulic system further comprises a differential pressure detecting module 4, the control method provided by the present invention comprising detecting the difference between the highest load pressure of the plurality of actuators 2 and the outlet pressure of the variable pump 1 using the differential pressure detecting module 4 Second pressure difference, at this time, the second pressure difference can be introduced into the controller, and the controller compares the second pressure difference with the set pressure of the differential pressure reduction width 32 corresponding to the actuator 2 having the highest load pressure. When the second pressure difference is greater than the set pressure of the differential pressure reduction width 32 corresponding to the actuator 2 having the highest load pressure, it indicates that an excessive flow of the system occurs, causing a problem that the pump outlet pressure rises. At this time, the output flow rate of the variable pump 1 is lowered by the controller, or the set flow rate of the flow control width 3 is increased, so that the second pressure difference is less than or equal to the differential pressure reduction corresponding to the actuator 2 having the highest load pressure. The setting pressure of the width 32. Therefore, it is possible to minimize the problems caused by the overflow of the system.

Specifically, in order to realize the detection of the second pressure difference, in the differential pressure detecting module 4, the shuttle width 41 is preferably disposed between the adjacent two hydraulic branches, and the shuttle widths 41 are connected in series to each other to the plurality of actuators 2 The highest load pressure is introduced into the differential pressure switch 42 in communication with the shuttle 41, so that the second differential pressure is obtained by the differential pressure switch 42. Then, the second differential pressure signal is transmitted to the controller through the differential pressure switch, and then the subsequent control operation is completed. The second pressure difference can also be obtained by a device or method known in the art such as a differential pressure sensor, which is not limited in the present invention.

In addition, when the system traffic is too large, it is necessary to release excess system traffic in time, although However, the system is provided with a safe overflow width 7 as the entire system, but since the set pressure is usually large, if it is only subjected to system overflow, unnecessary flow power loss is caused. Therefore, it is further preferred that a proportional width 5 having a set pressure can be set in the hydraulic system, and when the second pressure difference is greater than a set pressure of the proportional width 5, the ratio 5 is controlled to output the oil of the flow pump 1 The liquid partially leaks into the tank until the second pressure difference is less than or equal to the set pressure of the proportional width of 5. Therefore, the excess flow of the system can be vented back to the tank in time without waiting for the excess system flow to be greater than the set pressure of the overflow width 7, and then the discharge is started, so that the set pressure of the proportional width 5 is reasonably set lower than The set pressure of the overflow width of 7 can minimize the power loss of the system. In addition, although it is possible to vent excess flow through the proportional width 5, in practice, it is necessary to minimize such overflow. Therefore, in order to ensure that the excess flow rate is prevented from being discharged through the proportional width 5 before the control pressure is controlled by the controller to be equal to or less than the set pressure of the differential pressure reduction width 32, preferably, the ratio of the width 5 can be reasonably set. The constant pressure should be slightly greater than the set pressure of the differential pressure relief 32. Thereby minimizing the possibility of system flooding.

There are a plurality of embodiments with a wide ratio of 5. In particular, the ratio can be wide in the direction of hydraulic control, and more specifically, the liquid-controlled two-position two-way width, which is designed to have a control chamber, an oil inlet, and a return oil. The port communicates with one end of the control chamber with the outlet pressure of the variable pump 1, and the other end communicates with the shuttle width 41 in the differential pressure detecting module 4, connects the oil inlet port with the outlet of the variable pump, and communicates the oil return port with the oil tank. The ratio is such that the second pressure difference between the highest load pressure introduced from the shuttle 40 and the outlet pressure of the variable pump 1 is compared with the set pressure, and when the second pressure difference is greater than the set pressure, the system excess flow By this ratio is excluded, and since the proportional control is wide, the flow rate back to the tank can be changed in time according to the magnitude of the second differential pressure. Thereby the object of the invention is better achieved.

Finally, it should be noted that, in the present invention, since the hydraulic branches are connected in parallel, the outlet pressure of the variable pump 1 is the same as the inlet pressure of each flow control, so that in addition to the variable pressure pump in the process of obtaining the second differential pressure In addition to the outlet pressure of 1, it is also possible to detect the inlet pressure of each flow control width of 3. In fact, since there are pipelines and other hydraulic components that may be installed from the variable pump outlet to the inlets of each flow control width 3, the inlets of the wide 3 are controlled by direct detection of each flow rate. The pressure, and the difference between the highest load pressure and the inlet pressure corresponding to the flow control corresponding to the actuator that produces the highest load pressure, is more accurate.

In summary, the hydraulic system and the control method thereof provided by the invention can effectively reduce the possibility of system overflow and effectively reduce the power loss, and therefore, the engineering machine itself and the hydraulic system using the hydraulic system have high practicability and Promote value.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments, and various simple modifications of the technical solutions of the present invention may be made within the scope of the technical idea of the present invention. These simple variations are within the scope of the invention.

It should be further noted that the specific technical features described in the above specific embodiments may be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention has various possibilities. The combination method will not be described separately.

In addition, any combination of various embodiments of the invention may be made, as long as it does not deviate from the idea of the invention, and should also be regarded as the disclosure of the invention.

Claims

Rights request

A control method for a hydraulic system, the hydraulic system comprising a variable pump (1) and a plurality of actuators (2) driven by the variable pump (1), the plurality of actuators (2) being respectively connected in parallel a hydraulic branch is provided in communication with the variable pump (1), and a corresponding actuator (2) is disposed on the hydraulic branch between each actuator (2) and the variable pump (1) The flow control of the flow is wide (3), and the control method includes:

Calculating the required flow rate of the actuator (2) according to the working speed of each of the actuators (2);

Adjusting the displacement of the variable pump (1) such that the output flow of the variable pump (1) is equal to the sum of the demand flows;

And adjusting each of the flow control widths (3) such that the sum of the set flow rates of the flow control width (3) is equal to or greater than the output flow rate of the variable pump (1). 2. The control method of a hydraulic system according to claim 1, wherein when only one of the plurality of actuators (2) operates, the corresponding flow control is wide (3) Set the flow to the maximum.

3. The control method of a hydraulic system according to claim 1, characterized in that, when at least two actuators (2) are operated at the same time, and the operation of the partial actuator (2) needs to be stopped, the corresponding ones are first closed. The flow control is wide (3) and the displacement of the variable pump (1) is adjusted such that the output flow of the variable pump (1) is equal to the sum of the required flow of the still operating actuator (2). 4. The control method of a hydraulic system according to claim 1, wherein the speed control width is used as the flow control width (3), and the speed regulation wide design has a throttle width (31) and a difference reduction. The pressure is widened (32), and the differential pressure is widened (32) to maintain the throttle width (31). The first pressure difference between the inlet and the outlet is unchanged.

The control method of a hydraulic system according to claim 1, wherein the sum of the set flow rates is set to be 105% to 115% of the output flow rate.

The control method of a hydraulic system according to any one of claims 1 to 5, wherein the hydraulic system further comprises a differential pressure detecting module (4), the control method comprising using the differential pressure detecting module (4) detecting a second pressure difference between the highest load pressure in the plurality of actuators (2) and the variable pressure of the variable pump (1), when the second pressure difference is greater than and having the highest load pressure When the actuator (2) corresponds to the set pressure of the differential pressure reduction (32), the output flow of the variable pump (1) is decreased, or the flow control is increased (3) The flow rate is set such that the second pressure difference is less than or equal to a set pressure of the differential pressure reduction (32). 7. The control method of a hydraulic system according to claim 6, wherein in the differential pressure detecting module (4), a shuttle width (41) is provided between two adjacent hydraulic branches, And causing the shuttles (41) to be connected in series to introduce a highest load pressure in the plurality of actuators (2) into a differential pressure switch (42) communicating with the shuttle valve (41), thereby passing the pressure The difference switch (42) obtains the second pressure difference.

8. The control method of a hydraulic system according to claim 6, wherein a proportional width (5) is set in said hydraulic system, and said second pressure difference is greater than said proportional width (5) setting During pressure, the oil output from the variable pump (1) is partially discharged into the oil tank by the ratio (5) such that the second pressure difference is less than or equal to the set pressure of the proportional width (5) .

9. The method of controlling an oil system according to claim 8, wherein said ratio is The control chamber has a control chamber, an oil inlet and a return port, and the control chamber has one end and the variable pump.

The outlet pressure of (1) is in communication, and the other end is in communication with the differential pressure detecting module (4), the oil inlet is communicated with the outlet of the variable pump, and the oil return port is communicated with the oil tank. 10. A hydraulic system comprising a variable pump (1) and a plurality of actuators (2) driven by the variable pump (1), the plurality of actuators (2) respectively passing through a plurality of hydraulic fluids arranged in parallel a branch is connected to the variable pump (1), and the hydraulic branch between each actuator (2) and the variable pump (1) is provided with a flow for adjusting the corresponding actuator (2) The flow control is wide (3), characterized in that the hydraulic system further comprises a controller, wherein the controller is provided with the calculated actuator (2) according to the working speed of each of the actuators (2) Demand flow, where the controller is capable of:

Adjusting the displacement of the variable pump (1) such that the output flow of the variable pump (1) is equal to the sum of the demand flow values;

And adjusting each of the flow control widths (3) such that the sum of the set flow rates of the flow control width (3) is equal to or greater than the output flow rate of the variable pump (1).

11. The hydraulic system according to claim 10, wherein the flow control width (3) is a wide speed limit, and the speed adjustment includes a throttle width (31) and a differential pressure reduction in series. (32), the pressure difference constant width (32) for holding the throttle wide (31) a first inlet and an outlet pressure constant ₀

12. The hydraulic system according to claim 10, wherein the sum of the set flow rates is 105% to 115% of the output flow rate. The hydraulic system according to any one of claims 10 to 12, wherein the hydraulic system further comprises a differential pressure detecting module (4) for detecting the a second pressure difference between the highest load pressure in the plurality of actuators (2) and the variable pump (1) outlet pressure, when the second pressure difference is greater than the actuator having the highest load pressure ( 2) when the set pressure of the differential pressure reduction (32) is corresponding, the controller can control to reduce the output flow of the variable pump (1), or increase the flow control width (3) The flow rate is set such that the second pressure difference is less than or equal to a set pressure of the differential pressure reduction (32).

14. The hydraulic system according to claim 13, wherein the differential pressure detecting module (4) comprises a shuttle (41) disposed between two adjacent hydraulic branches and a shuttle

(41) a connected differential pressure switch (42), the plurality of coils (41) being connected in series to introduce a highest load pressure of the plurality of actuators (2) into the differential pressure switch (42), thereby passing The differential pressure switch (42) obtains the second differential pressure.

15. The hydraulic system according to claim 13, wherein the hydraulic system further comprises a proportional width (5) having a set pressure, and wherein the second differential pressure is greater than the proportional width (5) When the pressure is constant, the ratio is wide (5), and the oil outputted by the variable pump (1) is partially discharged into the oil tank, so that the second pressure difference is less than or equal to the set pressure of the proportional width (5). .

The hydraulic system according to claim 15, wherein the proportional width (5) comprises a control chamber, an oil inlet port and a oil return port, and one end of the control chamber communicates with an outlet of the variable pump (1) The other end is in communication with the differential pressure detecting module (4), and the oil inlet is in communication with an outlet of the variable pump, and the oil return port is in communication with the oil tank.

17. A construction machine, characterized in that the construction machine comprises the hydraulic system of claims 10-16.