阅读说明：本技术 变排量串联泵控电动静液执行器 (Variable displacement series pump control electric hydrostatic actuator ) 是由 陈革新 贾鹏硕 张�诚 刘会龙 张天贵 杨明昆 陆建新 仇庚廷 李渊 王泽铠 闫 于 2021-06-04 设计创作，主要内容包括：本发明涉及一种变排量串联泵控电动静液执行器,其包括动力模块、串联泵切换模块、补油模块、安全溢流模块、压力温度检测模块、执行机构模块和位置检测模块和用于各个元件之间连接的液压阀块,串联泵切换模块、压力温度检测模块和补油模块的一部分连接于液压阀块的上表面,安全溢流模块和补油模块的另一部分连接于液压阀块的右侧表面,执行机构模块连接于液压阀块的前表面,并基于此提出一种控制方法。本发明采用一体化的连接方式提高了系统的集成度,采用串联泵控系统解决方案提高了系统可靠性,有效避免了位置控制过程出现系统低速压力流量脉动现象,采用逻辑控制、位置闭环控制和系统报警控制三个部分组成的控制方法保证了系统高可靠性。(The invention relates to a variable-displacement series pump control electric hydrostatic actuator which comprises a power module, a series pump switching module, an oil supplementing module, a safety overflow module, a pressure temperature detection module, an actuating mechanism module, a position detection module and a hydraulic valve block for connecting all elements, wherein one part of the series pump switching module, the pressure temperature detection module and the oil supplementing module is connected to the upper surface of the hydraulic valve block, the other part of the safety overflow module and the other part of the oil supplementing module are connected to the right side surface of the hydraulic valve block, and the actuating mechanism module is connected to the front surface of the hydraulic valve block. The invention adopts an integrated connection mode to improve the integration level of the system, adopts a solution of a series pump control system to improve the reliability of the system, effectively avoids the low-speed pressure flow pulsation phenomenon of the system in the position control process, and adopts a control method consisting of three parts of logic control, position closed-loop control and system alarm control to ensure the high reliability of the system.)

1. A variable displacement series pump control electric hydrostatic actuator is characterized by comprising a power module, a series pump switching module, an oil supplementing module, a safety overflow module, a pressure temperature detection module, an actuating mechanism module, a position detection module and a hydraulic valve block for connecting all elements, wherein one part of the series pump switching module, the pressure temperature detection module and the oil supplementing module is connected to the upper surface of the hydraulic valve block, the other part of the safety overflow module and the oil supplementing module is connected to the right side surface of the hydraulic valve block, the actuating mechanism module is connected to the front surface of the hydraulic valve block,

the power module comprises a servo motor, a large-displacement hydraulic pump and a small-displacement hydraulic pump, the large-displacement hydraulic pump and the small-displacement hydraulic pump are arranged in series, and the servo motor is connected with the large-displacement hydraulic pump and the small-displacement hydraulic pump through a coupler;

the tandem pump switching module comprises a first two-position three-way electromagnetic directional valve, a second two-position three-way electromagnetic directional valve and a three-position four-way electromagnetic directional valve, the actuating mechanism module comprises an asymmetric oil cylinder, the first two-position three-way electromagnetic directional valve connects an oil outlet of the large displacement hydraulic pump and an oil inlet of the small displacement hydraulic pump with a rodless cavity of the asymmetric oil cylinder, the second two-position three-way electromagnetic directional valve connects an oil inlet of the large displacement hydraulic pump and an oil outlet of the small displacement hydraulic pump with a rod cavity of the asymmetric oil cylinder, the three-position four-way electromagnetic directional valve connects an oil inlet and an oil outlet of the large displacement hydraulic pump and an oil outlet of the small displacement hydraulic pump, the first two-position three-way electromagnetic directional valve, the second two-position three-way electromagnetic directional valve and the three-position four-way electromagnetic directional valve are matched with each other, so that the large displacement hydraulic pump supplies oil to the rodless cavity of the asymmetric oil The oil supply is switched to drive the asymmetric oil cylinder rod to extend or retract, and the position of the oil cylinder rod is controlled; the first two-position three-way electromagnetic reversing valve, the second two-position three-way electromagnetic reversing valve and the three-position four-way electromagnetic reversing valve are connected to the upper surface of the hydraulic valve block, and the asymmetric oil cylinder is connected to the front surface of the hydraulic valve block;

the oil supplementing module comprises an oil supplementing energy accumulator, a two-position two-way electromagnetic reversing valve, a first check valve and a second check valve, the oil supplementing energy accumulator is connected with the rodless cavity of the asymmetric oil cylinder through the two-position two-way electromagnetic reversing valve and is also connected with the rod cavity and the rodless cavity of the asymmetric oil cylinder through the first check valve and the second check valve, the oil supplementing energy accumulator and the two-position two-way electromagnetic reversing valve are connected to the upper surface of the hydraulic valve block, and the first check valve and the second check valve are connected to the right side surface of the hydraulic valve block.

2. The variable-displacement series pump-controlled electro-hydrostatic actuator according to claim 1, wherein the safety overflow module comprises a first safety overflow valve and a second safety overflow valve, oil inlets of the first safety overflow valve and the second safety overflow valve are respectively connected with the rod cavity and the rodless cavity of the asymmetric oil cylinder, oil outlets of the first safety overflow valve and the second safety overflow valve are respectively connected with the main oil way through a first check valve and a second check valve, and the first safety overflow valve and the second safety overflow valve are connected to the right side surface of the hydraulic valve block.

3. The variable displacement series pump controlled electro-hydrostatic actuator of claim 1, wherein the pressure and temperature detection module comprises a temperature sensor, a first pressure sensor, and a second pressure sensor, the temperature sensor is connected to the rod-containing chamber of the asymmetric cylinder, the first pressure sensor is connected to the rodless chamber of the asymmetric cylinder, and the second pressure sensor is connected to the rod-containing chamber of the asymmetric cylinder; the temperature sensor, the first pressure sensor and the second pressure sensor are connected to the upper surface of the hydraulic valve block.

4. The variable displacement series pump controlled electro-hydrostatic actuator of claim 1, wherein the position detection module includes a displacement sensor coupled to an end of the asymmetric cylinder rod.

5. A control method for a variable displacement series pump control electro-hydrostatic actuator according to any one of claims 1 to 4, characterized in that three parts of logic control, position closed-loop control and system alarm control are adopted, position instruction giving and position signal feedback of an upper computer and a controller are realized through bus or hardware cable signals, fault information such as alarm of the system is monitored in real time, and stable operation of the system and stable and reliable signal transmission are ensured; meanwhile, the controller can realize the logic control and the high-performance position closed-loop control of the system, and sends a control signal to the servo driver through a bus or an analog quantity, so that the servo motor can operate quickly and stably.

6. The variable displacement series pump controlled electro-hydrostatic actuator of claim 5, wherein the logic control specifically comprises the steps of:

s11, after the system is started, firstly, whether the pressure and the temperature of the system are normal is monitored through a pressure and temperature detection module, if the pressure of a low-pressure cavity is too low, or the pressure of a high-pressure cavity is too high, or the temperature is too low or too high, the system calls a motor open-loop control subprogram, and the motor is in a standby state;

s12, when the pressure and temperature of the system fed back by the pressure and temperature detection module is normal, if the system gives an alarm, the system calls a series pump switching subprogram to carry out emergency unloading;

and S13, if all the steps are normal, the system starts to work normally, a control instruction is given, a motor closed-loop control subprogram and a series pump switching subprogram are called, the cylinder rod of the oil cylinder is not located at the control instruction position, the servo oil cylinder quickly reaches the specified position according to a planned curve, and the position of the cylinder rod of the oil cylinder is maintained.

7. The variable displacement series pump controlled electro-hydrostatic actuator of claim 5, wherein the position closed loop control specifically comprises the steps of:

s21, a specified position instruction is given, the position of the oil cylinder rod is fed back to the controller in real time through the displacement sensor, the controller compares a fed-back position signal with the given position instruction through a motor closed-loop control subprogram, and a rotating speed control signal is output to control the rotation of the servo motor after the position signal is processed through a system program;

s22, feeding back actual rotating speed signals of the servo motor to the controller in real time, controlling the on-off of the electromagnetic directional valve through a series pump switching subprogram, and finally controlling the cylinder rod to move to a specified position to realize accurate position control;

and S23, when the system is abnormal, the upper computer sends a signal to the controller, the serial pump switching unit plays a role, unloading of the system is completed in a short time, and the system is protected.

Technical Field

The invention belongs to an electro-hydraulic servo control technology, and particularly relates to a variable-displacement series pump control electric hydrostatic actuator.

Background

The current typical control systems of the electro-hydraulic servo control system comprise two types, one is an electro-hydraulic servo valve control hydraulic system, and the other is an electro-hydraulic servo pump control hydraulic system (hereinafter referred to as an electric hydrostatic actuator).

The electro-hydraulic servo valve control hydraulic system needs a precise hydraulic servo valve and has high requirements on the quality of a working medium, so that the anti-pollution capability of the system is poor, and the later maintenance is inconvenient; the hydraulic power element, the executive element, the control element and the hydraulic auxiliary are connected by pipelines, so that the integration level is low, and the occupied area of the machine is large; the valve control hydraulic system has a large amount of overflow loss, so that energy waste is serious, and the system is heated seriously; compared with a valve control hydraulic system, the electric hydrostatic actuator has the characteristics of small equipment volume, simple pipeline arrangement, no overflow loss, high reliability, high safety, high precision and the like, and can effectively solve the inherent defects of the valve control hydraulic system, such as poor pollution resistance, low integration level, serious energy waste, high equipment installation cost, inconvenient maintenance and the like. In addition, compared with a valve control hydraulic system, the cost of the electric hydrostatic actuator is reduced by 50%, the occupied space is reduced by 80%, the energy consumption ratio is reduced by 80%, the power-weight ratio is improved by 60%, the equipment is energy-saving and noise-reducing, and the electric hydrostatic actuator is convenient to install and simple to maintain.

An electric hydrostatic actuator controls an asymmetric cylinder, a servo motor is generally adopted to drive a single bidirectional pump to supply oil to two cavities of the cylinder at present, if the effective acting areas of pistons of the two cavities of the asymmetric cylinder are greatly different, when the bidirectional pump switches the oil supply between the two cavities of a servo oil cylinder, low-speed pressure flow pulsation is easily generated in a system due to the large difference of the flow rates of the two cavities, and therefore the stability and the control performance of the system are influenced. Therefore, it is necessary and urgent to design a variable displacement tandem pump-controlled electro-hydrostatic actuator to achieve precise position control of the cylinder.

Disclosure of Invention

In view of the above situation, the present invention provides a variable displacement series pump control electro-hydrostatic actuator, which includes a power module, a series pump switching module, an oil supplementing module, a safety overflow module, a pressure temperature detection module, an actuator module, a position detection module, and a hydraulic valve block for connection between each element, wherein a portion of the series pump switching module, the pressure temperature detection module, and the oil supplementing module is connected to an upper surface of the hydraulic valve block, another portion of the safety overflow module and the oil supplementing module is connected to a right side surface of the hydraulic valve block, and the actuator module is connected to a front surface of the hydraulic valve block. The invention adopts an integrated connection mode to improve the integration level of the system, adopts a solution of a series pump control system to improve the reliability of the system, effectively avoids the low-speed pressure flow pulsation phenomenon of the system in the position control process, and adopts a control method consisting of three parts of logic control, position closed-loop control and system alarm control to ensure the high reliability of the system.

The invention provides a variable-displacement series pump control electric hydrostatic actuator which comprises a power module, a series pump switching module, an oil supplementing module, a safety overflow module, a pressure temperature detection module, an actuating mechanism module, a position detection module and a hydraulic valve block for connecting all elements, wherein one part of the series pump switching module, the pressure temperature detection module and the oil supplementing module is connected to the upper surface of the hydraulic valve block, the other part of the safety overflow module and the other part of the oil supplementing module are connected to the right side surface of the hydraulic valve block, the actuating mechanism module is connected to the front surface of the hydraulic valve block, the power module comprises a servo motor, a large-displacement hydraulic pump and a small-displacement hydraulic pump, the large-displacement hydraulic pump and the small-displacement hydraulic pump are arranged in series, and the servo motor is connected with the large-displacement hydraulic pump and the small-displacement hydraulic pump through couplers;

the tandem pump switching module comprises a first two-position three-way electromagnetic directional valve, a second two-position three-way electromagnetic directional valve and a three-position four-way electromagnetic directional valve, the actuating mechanism module comprises an asymmetric oil cylinder, the first two-position three-way electromagnetic directional valve connects an oil outlet of the large displacement hydraulic pump and an oil inlet of the small displacement hydraulic pump with a rodless cavity of the asymmetric oil cylinder, the second two-position three-way electromagnetic directional valve connects an oil inlet of the large displacement hydraulic pump and an oil outlet of the small displacement hydraulic pump with a rod cavity of the asymmetric oil cylinder, the three-position four-way electromagnetic directional valve connects an oil inlet and an oil outlet of the large displacement hydraulic pump and an oil outlet of the small displacement hydraulic pump, the first two-position three-way electromagnetic directional valve, the second two-position three-way electromagnetic directional valve and the three-position four-way electromagnetic directional valve are matched with each other, so that the large displacement hydraulic pump supplies oil to the rodless cavity of the asymmetric oil cylinder and the small displacement hydraulic pump supplies oil to the rod cavity of the asymmetric oil cylinder The oil supply is switched to drive the asymmetric oil cylinder rod to extend or retract, and the position of the oil cylinder rod is controlled; the first two-position three-way electromagnetic reversing valve, the second two-position three-way electromagnetic reversing valve and the three-position four-way electromagnetic reversing valve are connected to the upper surface of the hydraulic valve block, and the asymmetric oil cylinder is connected to the front surface of the hydraulic valve block;

the oil supplementing module comprises an oil supplementing energy accumulator, a two-position two-way electromagnetic reversing valve, a first check valve and a second check valve, the oil supplementing energy accumulator is connected with the rodless cavity of the asymmetric oil cylinder through the two-position two-way electromagnetic reversing valve and is also connected with the rod cavity and the rodless cavity of the asymmetric oil cylinder through the first check valve and the second check valve, the oil supplementing energy accumulator and the two-position two-way electromagnetic reversing valve are connected to the upper surface of the hydraulic valve block, and the first check valve and the second check valve are connected to the right side surface of the hydraulic valve block.

Further, the safety overflow module comprises a first safety overflow valve and a second safety overflow valve, oil inlets of the first safety overflow valve and the second safety overflow valve are respectively connected with the rod cavity and the rodless cavity of the asymmetric oil cylinder, oil outlets of the first safety overflow valve and the second safety overflow valve are respectively connected with the main oil way through the first check valve and the second check valve, and the first safety overflow valve and the second safety overflow valve are connected to the right side surface of the hydraulic valve block.

Preferably, the pressure and temperature detection module comprises a temperature sensor, a first pressure sensor and a second pressure sensor, the temperature sensor is connected with the rod cavity of the asymmetric oil cylinder, the first pressure sensor is connected with the rodless cavity of the asymmetric oil cylinder, and the second pressure sensor is connected with the rod cavity of the asymmetric oil cylinder; the temperature sensor, the first pressure sensor and the second pressure sensor are connected to the upper surface of the hydraulic valve block.

Preferably, the position detection module comprises a displacement sensor, and the displacement sensor is connected to the tail end of the asymmetric oil cylinder rod and used for monitoring the position of the cylinder rod in real time and feeding back the position to the controller.

On the other hand, the invention provides a control method for controlling the electro-hydrostatic actuator by using the variable displacement series pump, which adopts three parts of logic control, position closed-loop control and system alarm control, realizes position instruction giving and position signal feedback of an upper computer and a controller through bus or hardware cable signals, monitors fault information of the system such as alarm and the like in real time, and ensures stable operation of the system and stable and reliable signal transmission; meanwhile, the controller can realize the logic control and the high-performance position closed-loop control of the system, and sends a control signal to the servo driver through a bus or an analog quantity, so that the servo motor can operate quickly and stably.

Preferably, the logic control specifically includes the following steps:

s11, after the system is started, firstly, whether the pressure and the temperature of the system are normal is monitored through a pressure and temperature detection module, if the pressure of a low-pressure cavity is too low, or the pressure of a high-pressure cavity is too high, or the temperature is too low or too high, the system calls a motor open-loop control subprogram, and the motor is in a standby state;

s12, when the pressure and temperature of the system fed back by the pressure and temperature detection module is normal, if the system gives an alarm, the system calls a series pump switching subprogram to carry out emergency unloading;

and S13, if all the steps are normal, the system starts to work normally, a control instruction is given, a motor closed-loop control subprogram and a series pump switching subprogram are called, the cylinder rod of the oil cylinder is not located at the control instruction position, the servo oil cylinder quickly reaches the specified position according to a planned curve, and the position of the cylinder rod of the oil cylinder is maintained.

Preferably, the position closed-loop control specifically includes the following steps:

s21, a specified position instruction is given, the position of the oil cylinder rod is fed back to the controller in real time through the displacement sensor, the controller compares a fed-back position signal with the given position instruction through a motor closed-loop control subprogram, and a rotating speed control signal is output to control the rotation of the servo motor after the position signal is processed through a system program;

s22, feeding back actual rotating speed signals of the servo motor to the controller in real time, controlling the on-off of the electromagnetic directional valve through a series pump switching subprogram, and finally controlling the cylinder rod to move to a specified position to realize accurate position control;

and S23, when the system is abnormal, the upper computer sends a signal to the controller, the serial pump switching unit plays a role, unloading of the system is completed in a short time, and the system is protected.

The invention has the characteristics and beneficial effects that:

1. the invention provides a variable-displacement series pump-controlled electric hydrostatic actuator, which is characterized in that a servo motor coaxially drives two series large-displacement hydraulic pumps and two series small-displacement hydraulic pumps, and high-pressure oil ports and low-pressure oil ports of the series hydraulic pumps are connected with two load oil ports of a servo oil cylinder through an electromagnetic directional valve; the large displacement pump is responsible for supplying oil to the rodless cavity, the small displacement pump is responsible for supplying oil to the rod cavity, a control signal is output to the servo driver through the controller, the servo driver controls the servo motor, the rotating speed of the series hydraulic pump is changed, and therefore accurate position control of the oil cylinder is achieved.

2. The variable-displacement series pump control electric hydrostatic actuator provided by the invention has the advantages of high control precision of the traditional valve control equipment, and the like, and simultaneously avoids the defects of poor pollution resistance, low integration level, serious energy waste, high equipment installation cost, inconvenience in maintenance and the like.

3. The variable-displacement series pump-control electric hydrostatic actuator provided by the invention adopts an integrated connection mode, so that the integration level of the system is greatly improved; by adopting the solution of the series pump control system, the problem that the system has high requirement on the cleanliness of working medium oil is solved, and the reliability of the system is improved; the control system which consists of the logic control part, the position closed-loop control part and the system alarm control part ensures the high reliability of the system.

Drawings

FIG. 1 is a hydraulic control schematic diagram of a variable displacement series pump-controlled electro-hydrostatic actuator according to the present invention;

FIG. 2 is a block diagram of the position control of the variable displacement series pump controlled electro-hydrostatic actuator of the present invention;

FIG. 3 is a flow chart of the logic control of the variable displacement series pump controlled electro-hydrostatic actuator of the present invention;

FIG. 4 is a schematic diagram of a variable displacement series pump control electro-hydrostatic actuator physical device of the present invention.

In the figure:

1-a servo motor; 21-large displacement hydraulic pump; 22-small displacement hydraulic pump; 3-three-position four-way electromagnetic directional valve; 41-a two-position three-way electromagnetic directional valve I; 42-two-position three-way electromagnetic directional valve II; 5-oil supplement accumulator; 6-two-position two-way electromagnetic directional valve; 71-a one-way valve I; 72-one-way valve two; 81-a first safety overflow valve; 82-a second safety overflow valve; 9-a temperature sensor; 101-a pressure sensor one; 102-pressure sensor two; 11-an asymmetric oil cylinder; 12-a displacement sensor; 13-a valve block; 10-a power module; 20-a series pump switching module; 30-oil supplement module; 40-a safety overflow module; 50-a pressure temperature detection module; 60-an actuator module; 70-position detection module.

Detailed Description

The technical contents, structural features, attained objects and effects of the present invention are explained in detail below with reference to the accompanying drawings.

The invention provides a variable-displacement series pump control electric hydrostatic actuator, as shown in fig. 1, which comprises a power module 10, a series pump switching module 20, an oil supplementing module 30, a safety overflow module 40, a pressure and temperature detection module 50, an actuating mechanism module 60, a position detection module 70 and a hydraulic valve block 13 for connecting various elements, wherein the power module 10 comprises a servo motor 1, a large-displacement hydraulic pump 21 and a small-displacement hydraulic pump 22, the large-displacement hydraulic pump 21 and the small-displacement hydraulic pump 22 are arranged in series, and the servo motor 1 is connected with the large-displacement hydraulic pump 21 and the small-displacement hydraulic pump 22 through couplings and used as a power source of a system to provide required pressure and flow for the system.

The tandem pump switching module 20 comprises a first two-position three-way electromagnetic directional valve 41, a second two-position three-way electromagnetic directional valve 42 and a three-position four-way electromagnetic directional valve 3, the actuating mechanism module 60 comprises an asymmetric oil cylinder 11, the first two-position three-way electromagnetic directional valve 41 connects the oil outlet of a large displacement hydraulic pump 21 and the oil inlet of a small displacement hydraulic pump 22 with a rodless cavity of the asymmetric oil cylinder 11, the second two-position three-way electromagnetic directional valve 42 connects the oil inlet of the large displacement hydraulic pump 41 and the oil outlet of the small displacement hydraulic pump 42 with a rod cavity of the asymmetric oil cylinder 11, the three-position four-way electromagnetic directional valve 3 connects the oil inlet and the oil outlet of the large displacement hydraulic pump 21 and the small displacement hydraulic pump 22, the first two-position three-way electromagnetic directional valve 41, the second two-position three-way electromagnetic directional valve 42 and the three-position four-way electromagnetic directional valve 3 are mutually matched, so that the oil supply from the large displacement hydraulic pump 21 to the non-rod cavity of the asymmetric oil cylinder 11 and the small displacement hydraulic pump 22 to the rod cavity of the asymmetric oil cylinder 11 can be switched, the asymmetric oil cylinder rod 11 is driven to extend or retract, and the position of the oil cylinder rod is controlled.

The oil supplementing module 30 comprises an oil supplementing energy accumulator 5, a two-position two-way electromagnetic reversing valve 6, a first check valve 71 and a second check valve 72, wherein the oil supplementing energy accumulator 5 is connected with a rodless cavity of the asymmetric oil cylinder 11 through the two-position two-way electromagnetic reversing valve 6, and is also connected with a rod cavity and a rodless cavity of the asymmetric oil cylinder 11 through the first check valve 71 and the second check valve 72, so that the oil supplementing energy accumulator 5 can supplement oil or store oil when the system needs, and the oil supplementing module 30 plays two roles, namely, external leakage of the compensation system and asymmetric flow of the pump-controlled asymmetric oil cylinder 11 are compensated.

The safety overflow module 40 comprises a first safety overflow valve 81 and a second safety overflow valve 82, oil inlets of the first safety overflow valve 81 and the second safety overflow valve 82 are respectively connected with a rod cavity and a rodless cavity of the asymmetric oil cylinder 11, oil outlets of the first safety overflow valve 81 and the second safety overflow valve 82 are respectively connected with a main oil path through a first check valve 71 and a second check valve 72, and system pressure can be stabilized within a safety range when pressure overload occurs during system operation.

The pressure and temperature detection 50 module comprises a temperature sensor 9, a first pressure sensor 101 and a second pressure sensor 102, wherein the temperature sensor 9 is connected with a rod cavity of the asymmetric oil cylinder 11, the first pressure sensor 101 is connected with a rodless cavity of the asymmetric oil cylinder 11, and the second pressure sensor 102 is connected with a rod cavity of the asymmetric oil cylinder 11; the system pressure and the system temperature of the system are detected in real time, and the safe operation of the system is guaranteed.

The position detection module 60 comprises a displacement sensor 12, wherein the displacement sensor 12 is connected to the tail end of the rod of the asymmetric oil cylinder 11 and used for monitoring the position of the rod in real time and feeding back the position to the controller.

The specific implementation process is as follows:

when the large-displacement hydraulic pump 21 starts to supply oil to the asymmetric oil cylinder 11 under the driving of the servo motor 1, the small-displacement hydraulic pump 22 is unloaded through the three-position four-way electromagnetic directional valve 3, high-pressure hydraulic oil enters a rodless cavity of the asymmetric oil cylinder 11 through a pore passage in the hydraulic valve block and the first two-position three-way electromagnetic directional valve 41, a cylinder rod of the asymmetric oil cylinder 11 is driven to extend or retract, and the position of the cylinder rod of the oil cylinder is controlled. The low-pressure oil in the rod cavity of the asymmetric oil cylinder 11 and part of the hydraulic oil in the energy accumulator enter the oil suction port of the large-displacement hydraulic pump 21 through the second two-position three-way electromagnetic directional valve 42.

When the small-displacement hydraulic pump 22 starts to work under the driving of the servo motor 1, the large-displacement hydraulic pump 21 is unloaded through the three-position four-way electromagnetic directional valve 3, high-pressure hydraulic oil enters a rod cavity of the asymmetric oil cylinder 11 through a hole channel in the hydraulic valve block and the second two-position three-way electromagnetic directional valve 42, a cylinder rod of the asymmetric oil cylinder 11 is driven to extend or retract, and the position of the cylinder rod of the oil cylinder is controlled. Part of the low-pressure oil in the rodless cavity of the asymmetric oil cylinder 11 enters an oil suction port of the small-displacement hydraulic pump 22 through the first two-position three-way electromagnetic directional valve 41, and part of the low-pressure oil enters the oil supplementing energy accumulator 5 through the electromagnetic directional valve 6.

The first pressure sensor 101 and the second pressure sensor 102 and the temperature sensor 9 detect the pressure and temperature of the system. When the system needs unloading in emergency, the electromagnetic directional valve 3 is electrified, so that oil inlets and oil outlets of the large displacement hydraulic pump 21 and the small displacement hydraulic pump 22 are communicated, and unloading is realized.

According to the structural schematic diagram of the embodiment of the variable displacement series pump control electric hydrostatic actuator, as shown in fig. 4, a hydraulic valve block 13 connects all parts in a hydraulic system together, a first two-position three-way electromagnetic directional valve 41, a second two-position three-way electromagnetic directional valve 42, a three-position four-way electromagnetic directional valve 3, an oil supplementing energy accumulator 5, a two-position two-way electromagnetic directional valve 6 and a temperature sensor 9 are connected to the upper surface of the valve block 13, and a first pressure sensor 101 and a second pressure sensor 102 are connected to the upper surface of the valve block 13; the first check valve 71, the second check valve 72, the first relief and relief safety valve 81 and the second relief and relief safety valve 82 are connected to the right side surface of the valve block 13; the actuator module 60 is attached to the front surface of the hydraulic valve block 13. The three-position four-way electromagnetic directional valve 3 is responsible for switching on and off between oil inlet and outlet ports of the tandem pump, and the oil inlet and outlet ports of the large displacement hydraulic pump 21 and the small displacement hydraulic pump 22 are switched on when necessary to unload the oil; the first two-position three-way electromagnetic directional valve 41 and the second two-position three-way electromagnetic directional valve 42 are connected with the large displacement hydraulic pump 21, the small displacement hydraulic pump 22 and the working cavity of the asymmetric oil cylinder 11 to realize the on-off of an oil path; the oil supplementing accumulator 5 is connected with the first check valve 71 and the second check valve 72 to supplement oil to the side, with the rod, of the low-pressure cavity of the asymmetric oil cylinder 11, and is connected with the two-position two-way electromagnetic directional valve 6 to partially store the low-pressure oil on the side, without the rod, of the asymmetric oil cylinder 11. An oil inlet of the first safety overflow valve 81 is connected to one side of a rodless cavity of the asymmetric oil cylinder 11, an oil outlet of the first safety overflow valve is connected to one side of a rod cavity through the second check valve 72, and when the pressure of high-pressure oil on one side of the rodless cavity is too high, overflow can be generated, so that the safety of the system is protected; the oil inlet of the second safety overflow valve 82 is connected to one side of the rod cavity of the asymmetric oil cylinder 11, the oil outlet of the second safety overflow valve is connected to one side of the rodless cavity through the first check valve 71, and when the high-pressure oil on one side of the rod cavity is too high, overflow can be generated, so that the safety of the system is protected. The displacement sensor 12 is connected with the tail end of the asymmetric oil cylinder 11. The elements in the invention are connected through the hydraulic valve block 13, thereby improving the integration level of the equipment, reducing the leakage of the system equipment and improving the anti-pollution capability of the equipment.

On the other hand, the invention provides a control method for controlling the electro-hydrostatic actuator by using the variable displacement series pump, which adopts three parts of logic control, position closed-loop control and system alarm control, realizes position instruction giving and position signal feedback of an upper computer and a controller through bus or hardware cable signals, monitors fault information of the system such as alarm and the like in real time, and ensures stable operation of the system and stable and reliable signal transmission; meanwhile, the controller can realize the logic control and the high-performance position closed-loop control of the system, and sends a control signal to the servo driver through a bus or an analog quantity, so that the servo motor can operate quickly and stably.

As shown in fig. 2, the logic control specifically includes the following steps:

s11, after the system is started, whether the pressure and the temperature of the system are normal is monitored through the pressure and temperature detection module, if the pressure of the low-pressure cavity is too low, or the pressure of the high-pressure cavity is too high, or the temperature is too low or too high, the system calls an open-loop control subroutine of the motor, and the motor is in a standby state.

And S12, when the pressure and temperature of the system fed back by the pressure and temperature detection module is normal, if the system gives an alarm, the system calls a series pump switching subprogram to carry out emergency unloading.

And S13, if all the steps are normal, the system starts to work normally, a control instruction is given, a motor closed-loop control subprogram and a series pump switching subprogram are called, the cylinder rod of the oil cylinder is not located at the control instruction position, the servo oil cylinder quickly reaches the specified position according to a planned curve, and the position of the cylinder rod of the oil cylinder is maintained.

As shown in fig. 3, the position closed-loop control specifically includes the following steps:

and S21, a specified position instruction is given, the position of the oil cylinder rod is fed back to the controller in real time through the displacement sensor, the controller compares a fed-back position signal with the given position instruction through a motor closed-loop control subprogram, and a rotating speed control signal is output to control the rotation of the servo motor after the position signal is processed through a system program.

And S22, feeding back actual rotating speed signals of the servo motor to the controller in real time, controlling the on-off of the electromagnetic directional valve through a series pump switching subprogram, and finally controlling the cylinder rod to move to a specified position to realize accurate position control.

And S23, when the system is abnormal, the upper computer sends a signal to the controller, the serial pump switching unit plays a role, unloading of the system is completed in a short time, and the system is protected.

The invention provides a variable-displacement series pump-controlled electric hydrostatic actuator, which is characterized in that a servo motor coaxially drives two series large-displacement hydraulic pumps and two series small-displacement hydraulic pumps, and high-pressure oil ports and low-pressure oil ports of the series hydraulic pumps are connected with two load oil ports of a servo oil cylinder through an electromagnetic directional valve; the large displacement pump is responsible for supplying oil to the rodless cavity, the small displacement pump is responsible for supplying oil to the rod cavity, a control signal is output to the servo driver through the controller, the servo driver controls the servo motor, the rotating speed of the series hydraulic pump is changed, and therefore accurate position control of the oil cylinder is achieved; the valve control system has the advantages of high control precision of the traditional valve control equipment, and the like, and simultaneously avoids the defects of poor anti-pollution capacity, low integration level, serious energy waste, high equipment installation cost, inconvenience in maintenance and the like, and in an asymmetric cylinder hydraulic system, the phenomenon of system low-speed pressure flow pulsation in the position control process can be effectively avoided, and the stability of the system is improved; an integrated connection mode is adopted, so that the integration level of the system is greatly improved; by adopting the solution of the series pump control system, the problem that the system has high requirement on the cleanliness of working medium oil is solved, and the reliability of the system is improved; the control system which consists of the logic control part, the position closed-loop control part and the system alarm control part ensures the high reliability of the system.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope defined by the claims of the present invention.