CN106640575A - Electric hydraulic control mechanism - Google Patents

Abstract

The invention discloses an electro-hydraulic control mechanism, comprising: a first servo unit and a second servo unit, a fixed-value pressure reducing valve, a two-position three-way reversing valve, etc., the fixed-value pressure reducing valve generates a pressure difference, thereby A pressure signal is generated, and the pressure signal is converted into a mechanical signal of the first servo unit, thereby controlling the displacement of the plunger variable displacement pump. In the present invention, since the fixed-value decompression valve is provided, a servo relationship is established between the system pressure and the plunger variable pump, so that the plunger variable can be adjusted according to the column system pressure. The two-position three-way reversing valve of the present invention enables the plunger variable displacement pump to switch between two displacement adjustment modes.

Description

Electro-hydraulic control mechanism

technical field

The invention relates to the field of electromechanical technology, in particular to an electro-hydraulic control mechanism.

Background technique

In the hydraulic drive system and the hydraulic control system (the two may be collectively referred to as the hydraulic system), the system pressure or working pressure is controlled and determined by multiple units or systems. For example, usually, if the displacement of the variable pump does not occur large When changing, the system pressure of the hydraulic system is mainly limited by the relief valve. When the system pressure exceeds the control pressure of the relief valve, the relief valve returns the pressure to the set system pressure by draining oil to the oil tank, and the relief valve returns to the set system pressure through the relief valve. The pressure fluctuation of the valve control system is limited. In other words, when the displacement of the variable pump changes greatly, such as the displacement of the variable pump becomes larger, the system pressure will not be reduced to the set value even if the relief valve continuously drains oil. pressure, and the relief valve will soon be damaged. Therefore, it is necessary to adjust the displacement of the variable pump.

In the prior art, there are many mechanisms and methods for adjusting or changing the displacement of the variable pump. For example, the displacement of the plunger variable pump can be changed by changing the slope of the swash plate. The servo piston adjustment, specifically, the servo piston is set in the servo piston chamber, the connecting rod protrudes from one end of the servo piston chamber and changes the inclination of the swash plate through telescopic, the servo piston chamber has a spring in the chamber with the connecting rod, from The oil outlet of the plunger variable displacement pump leads a hydraulic oil to the chamber without the piston rod. The expansion and contraction of the connecting rod is changed through the pressure of the hydraulic oil, thereby changing the inclination of the swash plate, and then changing the piston rod of the plunger variable displacement pump. displacement. However, this method can only be used simply to change the displacement of the variable displacement pump, and can only be used to roughly adjust the displacement of the variable displacement pump before using the displacement pump when the required displacement of the system is known or predicted. The method does not adjust the displacement of the variable pump in real time according to the system pressure so that the displacement of the variable pump meets the working pressure requirements, or this method can only make the adjusted displacement roughly meet the system requirements, and the accuracy is poor.

Another method for adjusting the variable displacement plunger pump has appeared in the prior art. On the one hand, the inclination of the swash plate of the variable displacement pump is obtained through an angle sensor, and the angle sensor transmits the inclination signal to the electromagnetic controller, and the electromagnetic controller There is an electric signal corresponding to the slope; on the other hand, the hydraulic oil of the system enters the two chambers divided by the piston respectively, and the connecting rod on the piston is used to change the slope of the swash plate by moving with the piston. When the controller needs to change the displacement of the variable pump, the controller changes the pressure of the two hydraulic oils, thereby changing the displacement of the piston, and then changing the displacement of the variable pump. However, this method only correlates the slope of the swash plate of the variable pump with the electrical signal of the controller, and the pressure of the hydraulic system is only used as the power to simply change the lateral movement of the piston, and is not related to the displacement of the variable pump. Therefore, this method cannot adjust the displacement of the variable pump according to the system pressure, so that the adjusted displacement can only roughly meet the system requirements, and the accuracy is poor.

Contents of the invention

In view of the above technical problems in the prior art, the embodiment of the present invention provides an electro-hydraulic control mechanism that adjusts the displacement of the variable pump in real time according to the pressure signal fed back from the system hydraulic oil to make the system pressure conform to the predetermined pressure.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

An electro-hydraulic control mechanism used to adjust the pressure of the hydraulic system by changing the displacement of the plunger variable pump, including:

A first servo unit, which includes a first housing formed with a first chamber, is disposed in the first chamber, and divides the first chamber into a first left chamber and a first right chamber The first servo piston; the first left chamber is provided with a first spring for pushing against the first servo piston, wherein,

The action of the first servo piston and the inclination of the swash plate of the plunger variable displacement pump are configured in the following linkage relationship:

When the first servo piston moves horizontally to the left, the first servo piston makes the slope of the swash plate of the plunger variable displacement pump decrease; when the first servo piston moves horizontally to the right, the the first servo piston increases the inclination of the swash plate of the piston displacement pump;

The electro-hydraulic control mechanism also includes

Fixed-value decompression valve, the hydraulic oil of the system is divided into two channels to feed into the first left chamber and the first right chamber respectively, and the fixed-value decompression valve is set at the On the pipeline, so that the pressure of the hydraulic oil in the first left chamber is kept constant, so that the difference between the pressure of the hydraulic oil in the first right chamber and the pressure of the hydraulic oil in the first left chamber It increases with the pressure of the hydraulic oil in the system;

The second servo unit, which includes a second housing formed with a second chamber, is arranged in the second chamber, and divides the second chamber into a second left chamber and a second right chamber A second servo piston, a second spring is provided in the second left chamber and the second right chamber, and the second servo piston moves synchronously with the first servo piston;

Two-position three-way reversing valve 80, which has a first position that connects the system hydraulic oil to the first servo unit and simultaneously disconnects the second servo unit, and connects the system hydraulic oil to the first servo unit a second position that is disconnected and simultaneously connected to the second servo unit;

The first control unit includes a first valve body formed with a first valve cavity and a first valve core disposed in the first valve body, and the first control unit is used to respectively pass the system hydraulic oil into the The second left chamber and the second right chamber control the pressure of the hydraulic oil in the second left chamber and the second right chamber by moving the first spool;

A controller, which is used to control the first control unit according to the slope signal fed back by the angle sensor in the piston variable displacement pump, so that when the slope signal obtained by the controller is greater than a predetermined slope, the controller controls the The first spool of the first control unit moves so that the pressure of the hydraulic oil in the second left chamber is lower than the pressure of the hydraulic oil in the second right chamber; when the slope signal obtained by the controller is less than a predetermined slope , the controller controls the first spool of the first control unit to move so that the pressure of the hydraulic oil in the second left chamber is greater than the pressure of the hydraulic oil in the second right chamber.

Preferably, it also includes a third servo unit and a second control unit, the first servo piston and the second servo piston are commonly connected with a first push rod;

The third servo unit, which includes a third housing formed with a third chamber, is disposed in the third chamber, and divides the third chamber into a third left chamber and a third right chamber The third servo piston of the chamber and the second push rod fixedly connected with the third servo piston, the third left chamber is provided with a third spring, the second push rod is used to drive the swash plate, and : when the second push rod moves to the left, the slope of the swash plate decreases, and when the second push rod moves to the right, the slope of the swash plate increases;

The second control unit includes a second valve body formed with a second valve cavity and a second valve core disposed in the second valve cavity, the second valve core is driven by the first push rod, and System hydraulic oil is supplied to the third right chamber through the second control unit so that:

When the first push rod moves to the left, the first push rod drives the second spool to move to increase the pressure of the hydraulic oil in the third right chamber; when the first push rod When moving to the right, the first push rod drives the second valve core to move to reduce the pressure of the hydraulic oil in the third right chamber.

Preferably, it is characterized in that the second control unit is a proportional reversing valve, the oil outlet of the proportional reversing valve communicates with the third right chamber, the oil inlet communicates with the system hydraulic oil, and when When the second spool moves to the left, the pressure of the hydraulic oil at the oil outlet increases to increase the pressure of the hydraulic oil in the third right chamber; when the second spool moves to the right, The pressure of the hydraulic oil at the oil outlet is reduced to reduce the pressure of the hydraulic oil in the third right chamber.

Compared with the prior art, the beneficial effect of the electro-hydraulic control mechanism provided by the embodiment of the present invention is: the present invention sets up a fixed-value decompression valve to establish a servo relationship between the system pressure and the plunger variable pump, so that The plunger variable can be adjusted according to the column system pressure. The present invention is also provided with a two-position three-way reversing valve, so that the plunger variable displacement pump can be switched between two displacement adjustment modes.

Description of drawings

Fig. 1 is a structural diagram of the electro-hydraulic control mechanism of the present invention.

In the picture:

10-the first servo unit; 11-the first left chamber; 12-the first right chamber; 13-the first servo piston; 14-the first spring; 15-the first push rod; 20-the second servo unit; 21-the second left chamber; 22-the second right chamber; 23-the second servo piston; 24-the second spring; 30-the third servo unit; 31-the third left chamber; 32-the third right chamber Chamber; 33-the third servo piston; 34-the third spring; 35-the second push rod; 40-the first control unit; 41-the first spool; 50-the second control unit; 51-the second spool; 60-fixed pressure reducing valve; 70-piston variable pump; 71-swash plate; 80-two-position three-way reversing valve.

detailed description

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

In order to facilitate the description of the purpose, technical solutions and advantages of the electro-hydraulic control mechanism of the present invention, before introducing the electro-hydraulic control mechanism of the present invention, firstly introduce how the displacement of the variable displacement pump is changed in the prior art and this type The method should mainly be used in what situation.

The variable displacement pumps in the prior art, especially the plunger variable displacement pump 70, usually change the displacement of the variable displacement pump by changing the inclination of the swash plate 71. Before the variable displacement pump is connected to the hydraulic system as a power source, it is necessary to The hydraulic oil flow requirements, system pressure requirements and working pressure requirements adjust the displacement of the variable pump, that is to say, adjust the slope of the swash plate 71 of the variable pump so that the displacement of the variable pump roughly meets the hydraulic system. Requirements, so that after the variable pump is connected to the system, the pressure of the hydraulic system remains stable.

Usually, the displacement of the variable pump is positively correlated with the flow, system pressure and working pressure of the hydraulic system, that is to say, in the same hydraulic system, the larger the displacement of the variable pump is, the more the flow, system pressure and working pressure of the hydraulic system will be. The greater the pressure, and vice versa. When the displacement of the variable pump is determined, the flow rate, system pressure and working pressure of the hydraulic system will be roughly determined within a certain range. However, the displacement of the variable pump does not have a completely corresponding relationship with the flow rate, system pressure and working pressure of the hydraulic system. For example, when the displacement of the variable pump is Xv/s, the system pressure does not have a unique relationship with the displacement. Corresponding to a certain pressure, the system pressure at this time may change or fluctuate in a large range, and this fluctuation may exceed the allowable range of the system pressure, such as exceeding the rated pressure of the system (under the rated pressure, The components of the system can work normally). One of the most important reasons why the displacement of the variable pump does not correspond exactly to the flow rate, system pressure and working pressure of the hydraulic system is: the oil leakage and oil leakage of the various hydraulic components in the system, and the inevitable resistance of the hydraulic components to the hydraulic oil. Changes and aging of hydraulic components, etc.

In the prior art, the adjustment of the hydraulic system is based on the one-to-one relationship between the displacement of the variable pump and the parameters of the system. For example, if you want to adjust the system pressure to a certain pressure value, you only need to set the variable The inclination of the swash plate 71 of the pump can be adjusted to a certain displacement of the variable pump uniquely corresponding to the pressure value. That is to say, it is only necessary to adjust the swash plate 71 to a predetermined inclination alone.

For example, the inclination of the swash plate 71 is adjusted by a servo piston provided with a connecting rod. Specifically, the servo piston is arranged in the servo piston chamber, and the connecting rod protrudes from one end of the servo piston chamber to change the inclination of the swash plate 71 by stretching. The servo piston chamber has a spring in the chamber with the connecting rod, and a hydraulic oil is drawn from the oil outlet of the plunger variable pump 70 into the chamber without the piston rod, and the expansion and contraction of the connecting rod is changed by the pressure of the hydraulic oil , thereby changing the inclination of the swash plate 71, thereby changing the displacement of the plunger variable displacement pump 70.

For another example, on the one hand, the inclination of the swash plate 71 of the variable pump is obtained through an angle sensor, and the angle sensor transmits the inclination signal to the electromagnetic controller, and the electromagnetic controller has an electrical signal corresponding to the inclination one by one; on the other hand On the one hand, the hydraulic oil of the system enters into the two chambers divided by the piston respectively in two ways, and the connecting rod on the piston is used to change the inclination of the swash plate 71 by moving with the piston; when the controller needs to change the displacement of the variable pump , the controller changes the pressure of the two hydraulic oils, thereby changing the displacement of the piston, and then changing the displacement of the variable pump.

The above two methods are based on the situation that the displacement of the variable pump and the parameters of the system are in one-to-one correspondence. Corresponding relationship, so that this method can only be used simply to change the displacement of the variable pump, and can only be used to roughly adjust the displacement of the variable pump before using the variable pump when the required displacement of the system is known or predicted .

In the above-mentioned adjustment method in the prior art, the system hydraulic oil is only used as the power to simply change the lateral movement of the piston, and is not related to the displacement of the variable pump. The entire adjustment process is completely dependent on the controller and the inclination of the swash plate 71 fed back to the controller, and is not adjusted in real time according to the pressure of the hydraulic system, which is separated from the hydraulic system.

A bigger disadvantage of the above adjustment method is: due to the long-term use of the variable pump, the displacement corresponding to a certain slope of the swash plate 71 will change, so that the value stored in the controller will deviate from the displacement of the variable pump , so that: when the controller issues an instruction to adjust the swash plate 71 to a certain slope to adjust the variable displacement pump to the corresponding displacement, although the swash plate 71 on the variable displacement pump is adjusted to a predetermined slope, the displacement will not reach the predetermined displacement.

The above-mentioned method of adjusting the system pressure by adjusting the displacement of the variable pump is not accurate enough or does not meet the adjustment expectations. quantity. The purpose of the electro-hydraulic control mechanism of the present invention is to establish the relationship between the pressure of the hydraulic system and the displacement of the variable pump, that is, to establish the adjustment of the displacement of the variable pump according to the system pressure, and the adjustment of the displacement of the variable pump can affect the system pressure. servo relationship.

As shown in Figure 1, the embodiment of the present invention discloses an electro-hydraulic control mechanism for adjusting the pressure of the hydraulic system by changing the displacement of the plunger variable displacement pump 70. The electro-hydraulic control mechanism specifically includes: a first servo Unit 10 , second servo unit 20 , first control unit 40 , two-position three-way reversing valve 80 , controller and fixed-value decompression valve 60 .

The first servo unit 10 includes a first housing formed with a first chamber, is arranged in the first chamber, and divides the first chamber into a first left chamber 11 and a first right chamber 12. Piston 13; the first left chamber 11 is provided with a first spring 14 for pushing against the first servo piston 13, wherein,

The action of the first servo piston 13 and the inclination of the swash plate 71 of the plunger variable displacement pump 70 are arranged in the following linkage relationship:

When the first servo piston 13 moves horizontally to the left, the first servo piston 13 reduces the inclination of the swash plate 71 of the plunger variable displacement pump 70; when the first servo piston 13 moves horizontally to the right, the first servo piston 13 Make the inclination of the swash plate 71 of the plunger variable displacement pump 70 increase;

Fixed-value decompression valve 60, the hydraulic oil of the system is divided into two paths and respectively fed into the first left chamber 11 and the first right chamber 12, and the fixed-value decompression valve 60 is arranged on the pipeline leading into the first left chamber 11, To keep the pressure of the hydraulic oil in the first left chamber 11 constant, so that the difference between the pressure of the hydraulic oil in the first right chamber 12 and the pressure of the hydraulic oil in the first left chamber 11 varies with the system hydraulic pressure Increased oil pressure increases;

The second servo unit 20 includes a second housing formed with a second chamber, disposed in the second chamber, and dividing the second chamber into a second left chamber 21 and a second right chamber 22. The piston 23, the second left chamber 21 and the second right chamber 22 are provided with a second spring 24, and the second servo piston 23 moves synchronously with the first servo piston 13;

The two-position three-way reversing valve 80 has a first position for connecting the system hydraulic oil to the first servo unit 10 and simultaneously disconnecting it from the second servo unit 20 and disconnecting the system hydraulic oil from the first servo unit 10 while simultaneously disconnecting it from the second servo unit 20. The second position to which the second servo unit 20 is connected;

The first control unit 40 includes a first valve body formed with a first valve chamber and a first valve core 41 disposed in the first valve body, and the first control unit 40 is used to pass the system hydraulic oil into the second left chamber respectively 21 and the second right chamber 22 and control the pressure of the hydraulic oil in the second left chamber 21 and the second right chamber 22 by moving the first spool 41;

The controller is used to control the first control unit 40 according to the slope signal fed back by the angle sensor in the plunger variable displacement pump 70, so that when the slope signal obtained by the controller is greater than a predetermined slope, the controller controls the first valve of the first control unit 40 The core 41 moves so that the pressure of the hydraulic oil in the second left chamber 21 is less than the pressure of the hydraulic oil in the second right chamber 22; when the controller obtains the slope signal less than the predetermined slope, the controller controls the first The first spool 41 of the control unit 40 moves to make the pressure of the hydraulic oil in the second left chamber 21 greater than the pressure of the hydraulic oil in the second right chamber 22 .

In this way, when the two-position three-way reversing valve 80 is in the first position, even if the system hydraulic oil is connected to the first servo unit 10 and simultaneously disconnected from the second servo unit 20, and the system pressure increases (for some reason , when the displacement of the plunger variable pump 70 increases, the oil port of the control element becomes smaller, etc.), the pressure of the hydraulic oil in the first right chamber 12 increases, while the hydraulic oil in the first left chamber 11 The pressure of the fixed value pressure reducing valve 60 is controlled by the constant pressure, so that the first servo piston 13 moves to the left, and the movement of the first servo piston 13 makes the inclination of the swash plate 71 of the plunger variable displacement pump 70 decrease; thus The displacement of the plunger variable displacement pump 70 is reduced, and the reduced displacement of the plunger variable displacement pump 70 offsets the rising system pressure. When the first servo piston 13 moves to the right, the first servo piston 13 increases the inclination of the swash plate 71 of the plunger variable displacement pump 70; When the displacement decreases, the oil port of the control element becomes larger, etc.), the pressure of the hydraulic oil in the first right chamber 12 decreases, and the pressure of the hydraulic oil in the first left chamber 11 is decompressed due to the fixed value The control pressure of the valve 60 remains constant, so that the first servo piston 13 moves to the right, and the movement of the first servo piston 13 increases the slope of the swash plate 71 of the plunger variable displacement pump 70, so that the displacement of the plunger variable displacement pump 70 Increase, the displacement of the plunger variable displacement pump 70 is increased to compensate for the decreased system pressure.

The electro-hydraulic control mechanism of the present invention establishes the relationship between the system pressure and the displacement of the plunger variable pump 70, so that the system pressure can only be adjusted through the change of the displacement of the plunger variable pump 70, thus eliminating the need for adjustments to affect the system pressure. The process of other hydraulic components, so that the adjustment process is simple and precise. The reason why the system pressure can be adjusted simply and accurately in this process is that although there are many factors affecting the system pressure, the system pressure can be changed and adjusted by changing the displacement of the plunger variable displacement pump 70 .

The relationship between the system pressure established by the electro-hydraulic control mechanism of the present invention and the displacement of the plunger variable pump 70 is a servo relationship, that is to say, the system pressure can generate a pressure signal in real time, and the pressure signal can be directly or converted into a mechanical signal The displacement of the piston variable pump 70 is transmitted to the variable displacement pump 70 to change the displacement of the variable displacement pump 70, and the change of the displacement of the variable displacement pump 70 can affect the system pressure in real time, so that the system pressure reaches a constant value that meets the system requirements.

The electro-hydraulic control mechanism of the present invention changes the displacement of the plunger variable displacement pump 70 according to the system pressure, so that the adjusted system pressure can better meet the predetermined requirements.

The electro-hydraulic control mechanism of the present invention can adjust the displacement of the plunger variable displacement pump 70 according to the system pressure, and the key to establishing the servo relationship between the system pressure and the plunger variable displacement pump 70 lies in: the system pipe leading to the first left chamber 11 A fixed-value decompression valve 60 is set on the road, and the fixed-value decompression valve 60 makes the pressure of the hydraulic oil in the first left chamber 11 lower than the system pressure and is a fixed value that does not change with the system pressure, while the first right chamber The pressure of the hydraulic oil in 12 is equal to the system pressure, so that the pressure of the hydraulic oil in the first right chamber 12 and the pressure of the hydraulic oil in the first left chamber 11 form a pressure difference. The pressure difference refers to the difference between the system pressure required by the hydraulic system, that is, the rated pressure, and the pressure of the hydraulic oil in the first left chamber 11), and the first spring 14 is used to offset the predetermined pressure difference. At this time, The first servo piston 13 remains stationary, and when the system pressure exceeds or falls below the rated pressure, at this time, the first servo piston 13 moves under the action of the pressure difference, so that the swash plate 71 passes through the first servo piston 13 The slope changes due to the movement, thereby changing the displacement of the plunger variable displacement pump 70, and this change in displacement can just compensate or counteract the change in system pressure. For example, when the system pressure increases, the first servo piston 13 makes The displacement of the plunger variable displacement pump 70 decreases, and when the system pressure decreases, the first servo piston 13 causes the displacement of the plunger variable displacement pump 70 to increase.

The fixed-value decompression valve 60 of the electro-hydraulic control mechanism of the present invention is the decisive element for generating a pressure difference, and the condition for determining the servo relationship between the system pressure and the plunger variable displacement pump 70 is exactly the two ends of the first servo piston 13. Pressure difference.

The fixed-value decompression valve 60 of the electro-hydraulic control mechanism of the present invention also determines the rated pressure of the system, that is to say, under the premise that the elastic coefficient of the first spring 14 is constant, when the fixed-value decompression valve 60 sets a predetermined value , the system pressure is determined because: when the fixed value decompression valve 60 sets the predetermined value to A, at this moment, the system pressure should be equal to the hydraulic oil pressure corresponding to the predetermined value A (the first left chamber The sum of the pressure of the hydraulic oil in 11) FA and the thrust FB of the first spring 14, otherwise the first servo piston 13 will move. That is to say, when the set value of the fixed value pressure reducing valve 60 is determined, the system pressure will generate a pressure value corresponding to the set value; The required pressure value. Therefore, the fixed-value decompression valve 60 of the electro-hydraulic control mechanism of the present invention also has the function of adjusting the rated pressure of the system.

Since the electro-hydraulic control mechanism of the present invention is provided with a fixed-value decompression valve 60, it can accurately and repeatedly adjust the displacement of the plunger variable pump 70 according to the system pressure, so that the system pressure can be quickly and accurately adjusted to meet the requirements. Rated pressure, thereby reducing the pressure of the relief valve to maintain a constant system pressure and improving the service life of the relief valve.

As mentioned above, when the two-position three-way reversing valve 80 is in the first position, that is, the system hydraulic oil is connected to the first servo unit 10 and disconnected from the second servo unit 20 at the same time, the first servo unit 10 is used to make the swash plate The slope of 71 and the system pressure establish the above-mentioned servo relationship, so that the whole mechanism can adjust the displacement of the plunger variable pump 70 in real time according to the system pressure. This adjustment method is mostly used in the operation of the hydraulic system because it needs to be adjusted repeatedly. When the hydraulic system is running, it adjusts the fluctuation of the system pressure.

Before the hydraulic system is running, it is also necessary to preliminarily adjust the displacement of the plunger variable pump, so that after the hydraulic system is running, the system pressure will not deviate too much from the predetermined pressure, which is beneficial to pass the first pressure after the hydraulic system is running. A servo unit 10 and a fixed-value decompression valve 60 precisely adjust the hydraulic system.

For this reason, another key point of the present invention is that a two-position three-way reversing valve 80, a second servo unit 20, a controller, and a first control unit 40 are also provided. To enable the hydraulic system to be connected to the second servo unit 20, that is, when the two-position three-way reversing valve 80 is in the second position, it is convenient for the controller and the first control unit 40 to control the second servo unit 20, through the second servo unit 20 controls the displacement of the plunger variable displacement pump 70 . And the way of controlling the plunger variable displacement pump 70 through the controller, the first control unit 40 and the second control unit 50 is the way of controlling the plunger variable displacement pump 70 in the prior art described above, that is, through the controller to send Instructions, the inclination of the swash plate 71 is controlled by the instructions of the controller, and then the displacement of the plunger variable displacement pump 70 is controlled. At this time, the system pressure is used as the power to generate the mechanical signal, and does not participate in the adjustment of the comparison. The method of adjusting the displacement of the plunger variable displacement pump 70 in the prior art is of great significance to the adjustment of the plunger variable displacement pump 70 before the operation of the system. After operation, the hydraulic system can fluctuate within a certain range, so that it is convenient to use the fixed-value decompression valve 60 and the first servo unit 10 to precisely adjust the plunger variable pump 70 again.

In the present invention, by switching the two-position three-way reversing valve 80, the plunger variable pump 70 can be initially adjusted before the system is running, and the plunger variable pump 70 can be fine-tuned after the system is running, so that the system runs smoothly. .

In order to realize the linkage relationship between the action of the first servo piston 13 and the inclination of the swash plate 71 of the plunger variable displacement pump 70: that is, when the first servo piston 13 moves to the left, the first servo piston 13 makes the plunger variable displacement pump 70 The inclination of the swash plate 71 decreases; when the first servo piston 13 moves to the right, the first servo piston 13 increases the inclination of the swash plate 71 of the plunger variable displacement pump 70;

The electro-hydraulic control mechanism of the present invention also includes a third servo unit 30 and two second control units 50, the first servo piston 13 and the second servo piston 23 are jointly connected with a first push rod 15;

The third servo unit 30, which includes a third housing formed with a third chamber, is arranged in the third chamber, and divides the third chamber into a third left chamber 31 and a third right chamber 32. Three servo pistons 33 and a second push rod 35 fixedly connected with the third servo piston 33, the third left chamber 31 is provided with a third spring 34, the second push rod 35 is used to drive the swash plate 71, and: when the second When the push rod 35 moves to the left, the inclination of the swash plate 71 decreases, and when the second push rod 35 moves to the right, the inclination of the swash plate 71 increases;

The second control unit 50 includes a second valve body formed with a second valve cavity and a second valve core 51 arranged in the second valve cavity, the second valve core 51 is driven by the first push rod 15, and the system hydraulic oil passes through The second control unit 50 supplies oil to the third right chamber 32 so that:

When the first push rod 15 moves to the left, the first push rod 15 drives the second spool 51 to move so that the pressure of the hydraulic oil in the third right chamber 32 increases; when the first push rod 15 moves to the right , the first push rod 15 drives the second spool 51 to move to reduce the pressure of the hydraulic oil in the third right chamber 32 .

In this way, when the system hydraulic pressure increases, the first push rod 15 moves to the left, and the second push rod 35 also moves to the left through the control unit, so that the slope of the swash plate 71 decreases, and the displacement of the plunger variable displacement pump 70 When the system hydraulic pressure decreases, the first push rod 15 moves to the right, and the second push rod 35 also moves to the right through the control unit, so that the slope of the swash plate 71 increases, and the piston variable pump 70 Increased displacement.

The second control unit 50 is a proportional reversing valve. The oil outlet of the proportional reversing valve communicates with the third right chamber 32, and the oil inlet communicates with the system hydraulic oil. When the second spool 51 moves to the left, the outlet The pressure of the hydraulic oil in the oil port increases so that the pressure of the hydraulic oil in the third right chamber 32 increases; when the second spool 51 moves to the right, the pressure of the hydraulic oil in the oil outlet decreases so that the first The pressure of the hydraulic oil in the third right chamber 32 decreases.

Claims (3)

1. An electro-hydraulic control mechanism, which is used to adjust the pressure of the hydraulic system by changing the displacement of the plunger variable pump, is characterized in that it includes: A first servo unit, which includes a first housing formed with a first chamber, is disposed in the first chamber, and divides the first chamber into a first left chamber and a first right chamber The first servo piston; the first left chamber is provided with a first spring for pushing against the first servo piston, wherein, The action of the first servo piston and the inclination of the swash plate of the plunger variable displacement pump are configured in the following linkage relationship: When the first servo piston moves horizontally to the left, the first servo piston makes the slope of the swash plate of the plunger variable displacement pump decrease; when the first servo piston moves horizontally to the right, the the first servo piston increases the inclination of the swash plate of the piston displacement pump; Fixed-value decompression valve, the hydraulic oil of the system is divided into two channels to feed into the first left chamber and the first right chamber respectively, and the fixed-value decompression valve is set at the On the pipeline, so that the pressure of the hydraulic oil in the first left chamber is kept constant, so that the difference between the pressure of the hydraulic oil in the first right chamber and the pressure of the hydraulic oil in the first left chamber It increases with the pressure of the hydraulic oil in the system; The second servo unit, which includes a second housing formed with a second chamber, is arranged in the second chamber, and divides the second chamber into a second left chamber and a second right chamber A second servo piston, a second spring is provided in the second left chamber and the second right chamber, and the second servo piston moves synchronously with the first servo piston; Two-position three-way reversing valve 80, which has a first position that connects the system hydraulic oil to the first servo unit and simultaneously disconnects the second servo unit, and connects the system hydraulic oil to the first servo unit a second position that is disconnected and simultaneously connected to the second servo unit; The first control unit includes a first valve body formed with a first valve cavity and a first valve core disposed in the first valve body, and the first control unit is used to respectively pass the system hydraulic oil into the The second left chamber and the second right chamber control the pressure of the hydraulic oil in the second left chamber and the second right chamber by moving the first spool; A controller, which is used to control the first control unit according to the slope signal fed back by the angle sensor in the piston variable displacement pump, so that when the slope signal obtained by the controller is greater than a predetermined slope, the controller controls the The first spool of the first control unit moves so that the pressure of the hydraulic oil in the second left chamber is lower than the pressure of the hydraulic oil in the second right chamber; when the slope signal obtained by the controller is less than a predetermined slope , the controller controls the first spool of the first control unit to move so that the pressure of the hydraulic oil in the second left chamber is greater than the pressure of the hydraulic oil in the second right chamber. 2. The electro-hydraulic control mechanism according to claim 1, further comprising a third servo unit and a second control unit, the first servo piston and the second servo piston are commonly connected with a first pusher rod; The third servo unit, which includes a third housing formed with a third chamber, is disposed in the third chamber, and divides the third chamber into a third left chamber and a third right chamber The third servo piston of the chamber and the second push rod fixedly connected with the third servo piston, the third left chamber is provided with a third spring, the second push rod is used to drive the swash plate, and : when the second push rod moves to the left, the slope of the swash plate decreases, and when the second push rod moves to the right, the slope of the swash plate increases; The second control unit includes a second valve body formed with a second valve cavity and a second valve core disposed in the second valve cavity, the second valve core is driven by the first push rod, and System hydraulic oil is supplied to the third right chamber through the second control unit so that: When the first push rod moves to the left, the first push rod drives the second spool to move to increase the pressure of the hydraulic oil in the third right chamber; when the first push rod When moving to the right, the first push rod drives the second valve core to move to reduce the pressure of the hydraulic oil in the third right chamber. 3. The electro-hydraulic control mechanism according to claim 2, wherein the second control unit is a proportional reversing valve, and the oil outlet of the proportional reversing valve communicates with the third right chamber, The oil inlet is in communication with the system hydraulic oil, and when the second spool moves to the left, the pressure of the hydraulic oil in the oil outlet increases to increase the pressure of the hydraulic oil in the third right chamber; When the second spool moves to the right, the pressure of the hydraulic oil at the oil outlet decreases so that the pressure of the hydraulic oil in the third right chamber decreases.