阅读说明：本技术 一种可克服超越负载的电静液作动器及其控制方法 (Electro-hydrostatic actuator capable of overcoming overrunning load and control method thereof ) 是由 王承震 谢海波 侯永哲 韩瑞 于 2020-04-01 设计创作，主要内容包括：本发明公开了一种可克服超越负载的电静液作动器及其控制方法,所述可克服超越负载的电静液作动器包括调速电机、双向液压泵、油箱、第一补油单向阀、第二补油单向阀、第一比例溢流阀、回路单向阀、第二比例溢流阀、第一压力传感器、双向液压锁、第二压力传感器、液压缸及位移传感器。本发明中的一种可克服超越负载的电静液作动器,液压缸可在任意指定位置断电锁紧,有效降低系统能耗,且能够在存在超越负载工况的第二象限和第四象限稳定工作,通过设定第一比例溢流阀和第二比例溢流阀的调定压力有效降低系统压力损失,有效提高系统能效。(The invention discloses an electro-hydrostatic actuator capable of overcoming an overrunning load and a control method thereof. According to the electro-hydrostatic actuator capable of overcoming the overload, the hydraulic cylinder can be powered off and locked at any specified position, the energy consumption of the system is effectively reduced, the electro-hydrostatic actuator can stably work in the second quadrant and the fourth quadrant with the overload working condition, the pressure loss of the system is effectively reduced by setting the set pressure of the first proportional overflow valve and the second proportional overflow valve, and the energy efficiency of the system is effectively improved.)

1. An electro-hydrostatic actuator capable of overcoming an overrunning load is characterized by comprising a speed regulating motor, a bidirectional hydraulic pump, an oil tank, a first oil supplementing one-way valve, a second oil supplementing one-way valve, a first proportional overflow valve, a loop one-way valve, a second proportional overflow valve, a first pressure sensor, a bidirectional hydraulic lock, a second pressure sensor, a hydraulic cylinder and a displacement sensor;

the bidirectional hydraulic pump comprises a first oil port and a second oil port, the hydraulic cylinder comprises a rod cavity and a rodless cavity, and the bidirectional hydraulic lock comprises a first hydraulic control end, a first input end, a first output end, a second hydraulic control end, a second input end and a second output end;

the first oil port is respectively connected with the output end of the first oil supplementing one-way valve, the oil inlet of the first proportional overflow valve and the first input end of the bidirectional hydraulic lock; the second oil port is respectively connected with the output end of the second oil supplementing one-way valve and the input end of the loop one-way valve;

the oil tank is respectively connected with the input end of the first oil supplementing one-way valve, the input end of the second oil supplementing one-way valve, the oil return port of the first proportional overflow valve and the oil return port of the second proportional overflow valve;

the output end of the loop check valve is respectively connected with the oil inlet of the second proportional overflow valve and the second input end of the bidirectional hydraulic lock;

the first hydraulic control end of the bidirectional hydraulic lock is connected with the second input end of the bidirectional hydraulic lock, the second hydraulic control end of the bidirectional hydraulic lock is connected with the first input end of the bidirectional hydraulic lock, the first output end of the bidirectional hydraulic lock is connected with the rodless cavity of the hydraulic cylinder, and the second output end of the bidirectional hydraulic lock is connected with the rod cavity of the hydraulic cylinder;

the displacement sensor is arranged at the end part of the piston of the hydraulic cylinder; the first pressure sensor is connected to a pipeline of the first oil port connected with the first input end of the bidirectional hydraulic lock, and the second pressure sensor is connected to a pipeline of the loop check valve connected with the second input end of the bidirectional hydraulic lock;

the speed regulating motor is connected with the bidirectional hydraulic pump and is used for driving the bidirectional hydraulic pump; wherein, the speed regulating motor is a bidirectional motor.

2. The electro-hydrostatic actuator of claim 1, wherein the hydraulic cylinder is a single-rod asymmetric hydraulic cylinder.

3. The electro-hydrostatic actuator for overcoming an overrunning load of claim 2, wherein the first proportional relief valve and the second proportional relief valve are both cartridge proportional relief valves.

4. A method of controlling an electro-hydrostatic actuator capable of overcoming an overrunning load as defined in claim 3, comprising the steps of: judging working quadrants of the electro-hydrostatic actuator capable of overcoming the overrunning load, wherein the working quadrants comprise a first quadrant, a second quadrant, a third quadrant and a fourth quadrant;

wherein when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the first quadrant, the speed direction of the hydraulic cylinder is opposite to the direction of the external load force, the speed regulating motor rotates anticlockwise to drive a first oil port of the bidirectional hydraulic pump to discharge high-pressure oil, the high-pressure oil flows through the first input end and the first output end of the bidirectional hydraulic lock in sequence and then reaches the rodless cavity of the hydraulic cylinder, the piston of the hydraulic cylinder is pushed by external load force to move, so that the rod cavity of the hydraulic cylinder discharges oil outwards, the discharged oil flows through the second output end of the bidirectional hydraulic lock, because the pressure of the second hydraulic control end is led from the first input end to be high pressure, the second output end and the second input end are conducted in reverse direction, the return oil of the rod cavity of the hydraulic cylinder returns to the oil tank through the second proportional overflow valve, a first oil port of the bidirectional hydraulic pump sucks oil from the oil tank through the second oil supplementing one-way valve;

when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the second quadrant, the speed direction of the hydraulic cylinder is the same as the direction of external load force, the speed regulating motor rotates anticlockwise to drive the first oil port of the bidirectional hydraulic pump to discharge oil, the oil sequentially flows through the first input end and the first output end of the bidirectional hydraulic lock to the rodless cavity of the hydraulic cylinder, the external load force pushes the piston of the hydraulic cylinder to move so that the rod cavity of the hydraulic cylinder discharges the oil outwards, the rod cavity of the hydraulic cylinder is a high-pressure cavity and flows through the second output end of the bidirectional hydraulic lock, the set pressure of the second proportional pressure regulating valve is set to be larger than the external load force so that low-pressure exists in the rodless cavity of the hydraulic cylinder, and the first pressure sensor detects the pressures of the first input end and the second hydraulic control end of the bidirectional hydraulic lock so that the second output end can be conducted to the second input end in the reverse direction, high-pressure return oil of a rod cavity of the hydraulic cylinder returns to the oil tank through the second proportional overflow valve, and a first oil port of the bidirectional hydraulic pump absorbs oil from the oil tank through the second oil-supplementing one-way valve; the set pressure of the first proportional overflow valve is greater than the reverse opening pressure of the hydraulic control end of the bidirectional hydraulic lock, so that the oil discharged from the bidirectional hydraulic lock completely enters the rodless cavity of the hydraulic cylinder, and the running speed of the electro-hydrostatic actuator capable of overcoming the overrunning load is further increased; the high pressure of the rod cavity of the hydraulic cylinder is used for balancing the external load force and the pressure of the rodless cavity of the hydraulic cylinder, so that the electro-hydrostatic actuator capable of overcoming the overrunning load can stably work under the overrunning load;

when the electro-hydrostatic actuator capable of overcoming the overload works in a third quadrant, the speed direction of the hydraulic cylinder is opposite to the direction of external load force, the speed regulating motor rotates clockwise to drive a second oil port of the bidirectional hydraulic pump to discharge high-pressure oil, the high-pressure oil sequentially flows through the loop check valve, a second input end and a second output end of the bidirectional hydraulic lock to a rod cavity of the hydraulic cylinder, the external load force pushes a piston of the hydraulic cylinder to move so that a rodless cavity of the hydraulic cylinder discharges oil outwards and flows through a first output end of the bidirectional hydraulic lock, because the pressure of the first hydraulic control end is led from the second input end to be high pressure, the first output end is reversely conducted with the first input end, and an oil return part of the rodless cavity of the hydraulic cylinder enters the first oil port of the bidirectional hydraulic pump;

when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the fourth quadrant, the speed direction of the hydraulic cylinder is the same as the direction of external load force, the speed regulating motor rotates clockwise to drive a second oil port of the bidirectional hydraulic pump to discharge oil, the oil sequentially flows through the loop check valve, a second input end and a second output end of the bidirectional hydraulic lock to a rod cavity of the hydraulic cylinder, the external load force pushes a piston of the hydraulic cylinder to move so that the rodless cavity of the hydraulic pump discharges the oil outwards, and the oil sequentially flows through a first output end and a first input end of the bidirectional hydraulic lock and then enters the second oil port of the bidirectional hydraulic pump; the hydraulic cylinder is a single-rod asymmetric hydraulic cylinder, the oil return amount of a rodless cavity in the hydraulic cylinder is larger than the oil inlet amount of a rod cavity, when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the fourth quadrant, the pressure of the second proportional overflow valve is set to be larger than the reverse opening pressure of the hydraulic control end of the bidirectional hydraulic lock, the pressure of the first input end and the second hydraulic control end of the bidirectional hydraulic lock is detected by the second pressure sensor, so that the first output end and the first input end of the bidirectional hydraulic lock are conducted in reverse direction, setting the set pressure of the first proportional overflow valve to be larger than the external load pressure, enabling all return oil of the rodless cavity of the hydraulic cylinder to enter the first oil port of the bidirectional hydraulic pump, enabling the return oil quantity of the rodless cavity of the hydraulic cylinder to be equal to the product of the discharge capacity of the bidirectional hydraulic pump and the rotating speed of the motor, the differential flow of a rodless cavity and a rod cavity of the bidirectional hydraulic cylinder overflows and returns oil through the second proportional overflow valve; the first oil port of the bidirectional hydraulic pump is a high-pressure side oil port, and the second oil port of the bidirectional hydraulic pump is a low-pressure side oil port.

5. The method as claimed in claim 4, wherein when the electro-hydrostatic actuator capable of overcoming the overrunning load is operated in the first quadrant, the set pressure of the first proportional relief valve is greater than the external load force, so that the hydraulic cylinder can overcome the external load force and the oil discharged from the bidirectional hydraulic pump can completely enter the rodless cavity of the hydraulic cylinder, and the set pressure of the second proportional relief valve is in an unloading state, so that the energy consumption of the system is reduced.

6. The method as claimed in claim 4, wherein when the electro-hydrostatic actuator is operated in the third quadrant, the set pressure of the first proportional relief valve is in an unloading state to reduce the rod chamber pressure of the hydraulic cylinder, and the set pressure of the second proportional relief valve is greater than the external load force, so that the hydraulic cylinder can overcome the external load force and the oil discharged from the bidirectional hydraulic pump can be fully introduced into the rod chamber of the hydraulic cylinder.

Technical Field

The invention relates to the technical field of electro-hydrostatic actuators, in particular to an electro-hydrostatic actuator capable of overcoming an overrunning load and a control method thereof.

Background

The application of Electro-hydrostatic actuators (Electro-hydrostatic actuators) in industry is becoming more and more extensive, and compared with the traditional hydraulic actuating system, the Electro-hydrostatic actuators have the advantages of small volume, light weight, easy installation and maintenance and the like. Electro-hydrostatic actuators are used as execution driving units in multi-electric airplanes, industrial robots, heavy-duty mechanical arms and structural loading tests.

The electro-hydrostatic actuator generally adopts a motor to drive a bidirectional hydraulic pump to drive a hydraulic cylinder to reciprocate, and a reversing valve is omitted in an intermediate loop, so that the electro-hydrostatic actuator is essentially a pump cylinder control system. After an oil cylinder of the electro-hydrostatic actuator runs to a specified position, in order to keep the position of the oil cylinder unchanged under the action of an external load, a motor of the electro-hydrostatic actuator needs to keep running to compensate for the change of the displacement of the oil cylinder caused by the external load, and the system heating and energy conservation are adversely affected. In addition, when the electro-hydrostatic actuator works in the first quadrant or the third quadrant, the hydraulic cylinder can realize the action as long as the output pressure of the system is greater than the external load acting force, but when the electro-hydrostatic actuator works in the second quadrant or the fourth quadrant, because the acting direction of the load acting force is consistent with the running direction of the hydraulic cylinder, the over load exists, the oil outlet end of the bidirectional hydraulic pump is only used for supplementing oil, the pressure is not established at the outlet of the bidirectional hydraulic pump, the pressure is lower than the reverse opening pressure of the hydraulic lock, the hydraulic lock cannot be opened, the oil outlet cavity of the hydraulic cylinder is locked and cannot return oil, and therefore the hydraulic cylinder cannot run or runs in a shaking mode due to the fact that the hydraulic lock is in a frequent switch switching state. In view of the above, the present invention provides an electro-hydrostatic actuator that overcomes an overrunning load.

Disclosure of Invention

The invention aims to overcome the defects, and provides the electro-hydrostatic actuator capable of overcoming the overrunning load, wherein a hydraulic cylinder can be powered off and locked at any specified position, so that the energy consumption of the system is effectively reduced, the system can stably work in a second quadrant and a fourth quadrant with the overrunning load working condition, and the pressure loss of the system is reduced by setting the set pressure of a first proportional overflow valve and a second proportional overflow valve, so that the energy efficiency of the system is effectively improved; in addition, the invention also provides a control method of the electro-hydrostatic actuator capable of overcoming the overrunning load.

In order to achieve the above object, a first aspect of the present invention provides an electro-hydrostatic actuator capable of overcoming an overrunning load, including a speed-adjusting motor, a bidirectional hydraulic pump, an oil tank, a first oil-supplementing check valve, a second oil-supplementing check valve, a first proportional overflow valve, a loop check valve, a second proportional overflow valve, a first pressure sensor, a bidirectional hydraulic lock, a second pressure sensor, a hydraulic cylinder, and a displacement sensor;

the bidirectional hydraulic pump comprises a first oil port and a second oil port, the hydraulic cylinder comprises a rod cavity and a rodless cavity, and the bidirectional hydraulic lock comprises a first hydraulic control end, a first input end, a first output end, a second hydraulic control end, a second input end and a second output end;

the first oil port is respectively connected with the output end of the first oil supplementing one-way valve, the oil inlet of the first proportional overflow valve and the first input end of the bidirectional hydraulic lock; the second oil port is respectively connected with the output end of the second oil supplementing one-way valve and the input end of the loop one-way valve;

the oil tank is respectively connected with the input end of the first oil supplementing one-way valve, the input end of the second oil supplementing one-way valve, the oil return port of the first proportional overflow valve and the oil return port of the second proportional overflow valve;

the output end of the loop check valve is respectively connected with the oil inlet of the second proportional overflow valve and the second input end of the bidirectional hydraulic lock;

the first hydraulic control end of the bidirectional hydraulic lock is connected with the second input end of the bidirectional hydraulic lock, the second hydraulic control end of the bidirectional hydraulic lock is connected with the first input end of the bidirectional hydraulic lock, the first output end of the bidirectional hydraulic lock is connected with the rodless cavity of the hydraulic cylinder, and the second output end of the bidirectional hydraulic lock is connected with the rod cavity of the hydraulic cylinder;

the displacement sensor is arranged at the end part of the piston of the hydraulic cylinder; the first pressure sensor is connected to a pipeline of the first oil port connected with the first input end of the bidirectional hydraulic lock, and the second pressure sensor is connected to a pipeline of the loop check valve connected with the second input end of the bidirectional hydraulic lock;

the speed regulating motor is connected with the bidirectional hydraulic pump and is used for driving the bidirectional hydraulic pump; wherein, the speed regulating motor is a bidirectional motor.

The electro-hydrostatic actuator capable of overcoming the overrunning load is characterized in that the hydraulic cylinder is a single-rod asymmetric hydraulic cylinder.

The electro-hydrostatic actuator capable of overcoming the overrunning load is characterized in that the first proportional overflow valve and the second proportional overflow valve are plug-in proportional overflow valves.

In a second aspect, the present invention provides a method of controlling an electro-hydrostatic actuator capable of overcoming an overrunning load, comprising the steps of: judging working quadrants of the electro-hydrostatic actuator capable of overcoming the overrunning load, wherein the working quadrants comprise a first quadrant, a second quadrant, a third quadrant and a fourth quadrant;

wherein when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the first quadrant, the speed direction of the hydraulic cylinder is opposite to the direction of the external load force, the speed regulating motor rotates anticlockwise to drive a first oil port of the bidirectional hydraulic pump to discharge high-pressure oil, the high-pressure oil flows through the first input end and the first output end of the bidirectional hydraulic lock in sequence and then reaches the rodless cavity of the hydraulic cylinder, the piston of the hydraulic cylinder is pushed by external load force to move, so that the rod cavity of the hydraulic cylinder discharges oil outwards, the discharged oil flows through the second output end of the bidirectional hydraulic lock, because the pressure of the second hydraulic control end is led from the first input end to be high pressure, the second output end and the second input end are conducted in reverse direction, the return oil of the rod cavity of the hydraulic cylinder returns to the oil tank through the second proportional overflow valve, a first oil port of the bidirectional hydraulic pump sucks oil from the oil tank through the second oil supplementing one-way valve;

when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the second quadrant, the speed direction of the hydraulic cylinder is the same as the direction of external load force, the speed regulating motor rotates anticlockwise to drive the first oil port of the bidirectional hydraulic pump to discharge oil, the oil sequentially flows through the first input end and the first output end of the bidirectional hydraulic lock to the rodless cavity of the hydraulic cylinder, the external load force pushes the piston of the hydraulic cylinder to move so that the rod cavity of the hydraulic cylinder discharges the oil outwards, the rod cavity of the hydraulic cylinder is a high-pressure cavity and flows through the second output end of the bidirectional hydraulic lock, the set pressure of the second proportional pressure regulating valve is set to be larger than the external load force so that low-pressure exists in the rodless cavity of the hydraulic cylinder, and the first pressure sensor detects the pressures of the first input end and the second hydraulic control end of the bidirectional hydraulic lock so that the second output end can be conducted to the second input end in the reverse direction, high-pressure return oil of a rod cavity of the hydraulic cylinder returns to the oil tank through the second proportional overflow valve, and a first oil port of the bidirectional hydraulic pump absorbs oil from the oil tank through the second oil-supplementing one-way valve; the set pressure of the first proportional overflow valve is greater than the reverse opening pressure of the hydraulic control end of the bidirectional hydraulic lock, so that the oil discharged from the bidirectional hydraulic lock completely enters the rodless cavity of the hydraulic cylinder, and the running speed of the electro-hydrostatic actuator capable of overcoming the overrunning load is further increased; the high pressure of the rod cavity of the hydraulic cylinder is used for balancing the external load force and the pressure of the rodless cavity of the hydraulic cylinder, so that the electro-hydrostatic actuator capable of overcoming the overrunning load can stably work under the overrunning load;

when the electro-hydrostatic actuator capable of overcoming the overload works in a third quadrant, the speed direction of the hydraulic cylinder is opposite to the direction of external load force, the speed regulating motor rotates clockwise to drive a second oil port of the bidirectional hydraulic pump to discharge high-pressure oil, the high-pressure oil sequentially flows through the loop check valve, a second input end and a second output end of the bidirectional hydraulic lock to a rod cavity of the hydraulic cylinder, the external load force pushes a piston of the hydraulic cylinder to move so that a rodless cavity of the hydraulic cylinder discharges oil outwards and flows through a first output end of the bidirectional hydraulic lock, because the pressure of the first hydraulic control end is led from the second input end to be high pressure, the first output end is reversely conducted with the first input end, and an oil return part of the rodless cavity of the hydraulic cylinder enters the first oil port of the bidirectional hydraulic pump;

when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the fourth quadrant, the speed direction of the hydraulic cylinder is the same as the direction of external load force, the speed regulating motor rotates clockwise to drive a second oil port of the bidirectional hydraulic pump to discharge oil, the oil sequentially flows through the loop check valve, a second input end and a second output end of the bidirectional hydraulic lock to a rod cavity of the hydraulic cylinder, the external load force pushes a piston of the hydraulic cylinder to move so that the rodless cavity of the hydraulic pump discharges the oil outwards, and the oil sequentially flows through a first output end and a first input end of the bidirectional hydraulic lock and then enters the second oil port of the bidirectional hydraulic pump; the hydraulic cylinder is a single-rod asymmetric hydraulic cylinder, the oil return amount of a rodless cavity in the hydraulic cylinder is larger than the oil inlet amount of a rod cavity, when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the fourth quadrant, the pressure of the second proportional overflow valve is set to be larger than the reverse opening pressure of the hydraulic control end of the bidirectional hydraulic lock, the pressure of the first input end and the second hydraulic control end of the bidirectional hydraulic lock is detected by the second pressure sensor, so that the first output end and the first input end of the bidirectional hydraulic lock are conducted in reverse direction, setting the set pressure of the first proportional overflow valve to be larger than the external load pressure, enabling all return oil of the rodless cavity of the hydraulic cylinder to enter the first oil port of the bidirectional hydraulic pump, enabling the return oil quantity of the rodless cavity of the hydraulic cylinder to be equal to the product of the discharge capacity of the bidirectional hydraulic pump and the rotating speed of the motor, the differential flow of a rodless cavity and a rod cavity of the bidirectional hydraulic cylinder overflows and returns oil through the second proportional overflow valve; the first oil port of the bidirectional hydraulic pump is a high-pressure side oil port, and the second oil port of the bidirectional hydraulic pump is a low-pressure side oil port.

When the electro-hydrostatic actuator capable of overcoming the overrunning load works in the first quadrant, the set pressure of the first proportional overflow valve is larger than the external load force, so that the hydraulic cylinder can overcome the external load force and all the oil discharge of the bidirectional hydraulic pump enters a rodless cavity of the hydraulic cylinder, and the set pressure of the second proportional overflow valve is in an unloading state so as to reduce the energy consumption of the system.

When the electro-hydrostatic actuator capable of overcoming the overload works in the third quadrant, the set pressure of the first proportional overflow valve is in an unloading state so as to reduce the pressure of the rod cavity of the hydraulic cylinder, and the set pressure of the second proportional overflow valve 8 is greater than the external load force, so that the hydraulic cylinder can overcome the external load force and all the oil discharged by the bidirectional hydraulic pump enters the rod cavity of the hydraulic cylinder.

Compared with the prior art, the invention has the beneficial effects that: according to the electro-hydrostatic actuator capable of overcoming the overload, the hydraulic cylinder can be powered off and locked at any specified position, the energy consumption of the system is effectively reduced, the electro-hydrostatic actuator can stably work in the second quadrant and the fourth quadrant with the overload working condition, the pressure loss of the system is effectively reduced by setting the set pressure of the first proportional overflow valve and the second proportional overflow valve, and the energy efficiency of the system is effectively improved.

Drawings

FIG. 1 is a block diagram of one embodiment of an electro-hydrostatic actuator of the present invention that overcomes an overrunning load.

FIG. 2 is a schematic view of the fluid flow of the electro-hydrostatic actuator of FIG. 1 operating at a first quadrant against an overrunning load.

FIG. 3 is a schematic view of the fluid flow of the electro-hydrostatic actuator of FIG. 1 operating at a second quadrant against an overrunning load.

FIG. 4 is a schematic view of the fluid flow of the electro-hydrostatic actuator of FIG. 1 operating at a third quadrant against an overrunning load.

FIG. 5 is a schematic view of the fluid flow of the electro-hydrostatic actuator of FIG. 1 operating at a fourth quadrant against an overrunning load.

The correspondence between each mark and the part name is as follows:

the hydraulic control system comprises a speed regulating motor 1, a bidirectional hydraulic pump 2, an oil tank 3, a first oil supplementing one-way valve 4, a second oil supplementing one-way valve 5, a first proportional overflow valve 6, a loop one-way valve 7, a second proportional overflow valve 8, a first pressure sensor 9, a bidirectional hydraulic lock 10, a second pressure sensor 11, a hydraulic cylinder 12 and a displacement sensor 13.

Detailed Description

In order to make the technical means, the characteristics, the purposes and the functions of the invention easy to understand, the invention is further described with reference to the specific drawings.

The drawings attached to the present specification, the depicted structures, ratios, sizes, and the like are only used for matching the disclosure of the present specification, so that those skilled in the art can understand and read the present specification, and do not limit the conditions that the present invention can be implemented, so that the present specification does not have a substantial technical meaning, and any structural modifications, ratio changes, or size adjustments should still fall within the scope of the present disclosure without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.

Examples

Referring to fig. 1, the embodiment provides an electro-hydrostatic actuator capable of overcoming an overrunning load, which includes a speed-adjusting motor 1, a bidirectional hydraulic pump 2, an oil tank 3, a first oil-supplementing check valve 4, a second oil-supplementing check valve 5, a first proportional overflow valve 6, a loop check valve 7, a second proportional overflow valve 8, a first pressure sensor 9, a bidirectional hydraulic lock 10, a second pressure sensor 11, a hydraulic cylinder 12, and a displacement sensor 13.

The bidirectional hydraulic pump 2 comprises a first oil port and a second oil port, the hydraulic cylinder 12 comprises a rod cavity and a rodless cavity, and the bidirectional hydraulic lock 10 comprises a first hydraulic control end, a first input end, a first output end, a second hydraulic control end, a second input end and a second output end; the first oil port is an oil suction port of the bidirectional hydraulic pump 2 when the bidirectional hydraulic pump 2 rotates clockwise, and the second oil port is an oil suction port of the bidirectional hydraulic pump 2 when the bidirectional hydraulic pump 2 rotates counterclockwise. When the first oil port of the bidirectional hydraulic pump 2 is used as an oil suction port, oil can be sucked from the oil tank 3 through the first check valve 4, so that oil can be replenished to the second oil port. When the second port of the bidirectional hydraulic pump 2 is used as an oil suction port, oil can be sucked from the oil tank 3 through the second check valve 5, so that the first port is replenished with oil.

The first oil port is respectively connected with the output end of the first oil supplementing one-way valve 4, the oil inlet of the first proportional overflow valve 6 and the first input end of the bidirectional hydraulic lock 10; the second oil port is respectively connected with the output end of the second oil supplementing one-way valve 5 and the input end of the loop one-way valve 7.

The oil tank 3 is respectively connected with the input end of the first oil-supplementing one-way valve 4, the input end of the second oil-supplementing one-way valve 5, the oil return port of the first proportional overflow valve 6 and the oil return port of the second proportional overflow valve 8.

The output end of the loop check valve 7 is respectively connected with the oil inlet of the second proportional overflow valve 8 and the second input end of the bidirectional hydraulic lock 10.

The first hydraulic control end of the bidirectional hydraulic lock 10 is connected with the second input end of the bidirectional hydraulic lock 10, the second hydraulic control end of the bidirectional hydraulic lock 10 is connected with the first input end of the bidirectional hydraulic lock 10, the first output end of the bidirectional hydraulic lock 10 is connected with the rodless cavity of the hydraulic cylinder 12, and the second output end of the bidirectional hydraulic lock 10 is connected with the rod cavity of the hydraulic cylinder 12.

The displacement sensor 13 is mounted at the piston end of the hydraulic cylinder 12; the first pressure sensor 9 is connected to a pipeline with a first oil port connected to a first input end of the bidirectional hydraulic lock 10, and the second pressure sensor 11 is connected to a pipeline with a loop check valve 7 connected to a second input end of the bidirectional hydraulic lock 10. The first pressure sensor 9 is used for feeding back a pressure signal of a rodless cavity of the hydraulic cylinder 12, the second pressure sensor 11 is used for feeding back a pressure signal of a rod cavity of the hydraulic cylinder 12, and the displacement sensor 13 is used for feeding back a displacement signal of the hydraulic cylinder 12.

The speed regulating motor 1 is connected with the bidirectional hydraulic pump 2 and is used for driving the bidirectional hydraulic pump 2; wherein, the speed regulating motor 1 is a bidirectional motor.

The hydraulic cylinder 12 in this embodiment is a single-rod asymmetric hydraulic cylinder 12.

The first proportional overflow valve 6 and the second proportional overflow valve 8 in this embodiment are both plug-in proportional overflow valves, and the plug-in proportional overflow valves can effectively reduce the volume of the electro-hydrostatic actuator capable of overcoming the overrunning load.

FIG. 2 is a schematic fluid flow diagram illustrating operation of the electro-hydrostatic actuator of FIG. 1 at a first threshold, and the solid arrows in FIG. 2 represent the fluid flow directions of the electro-hydrostatic actuator at the first threshold.

FIG. 3 is a schematic view of the fluid flow direction of the electro-hydrostatic actuator of FIG. 1 operating at a second threshold, the solid arrows in FIG. 3 representing the fluid flow direction of the electro-hydrostatic actuator operating at the second threshold.

FIG. 4 is a schematic view of the fluid flow direction of the electro-hydrostatic actuator of FIG. 1 operating at a third quadrant with the load surmountable, and the solid arrows in FIG. 4 represent the fluid flow directions of the electro-hydrostatic actuator operating at the third quadrant with the load surmountable.

FIG. 5 is a schematic fluid flow diagram of the electro-hydrostatic actuator of FIG. 1 operating at a fourth quadrant with the load surmountable, and the solid arrows in FIG. 5 represent the fluid flow directions of the electro-hydrostatic actuator operating at the fourth quadrant with the load surmountable.

The present embodiment further provides a method of controlling an electro-hydrostatic actuator capable of overcoming an overrunning load, comprising the steps of: judging working quadrants of the electro-hydrostatic actuator capable of overcoming the overrunning load, wherein the working quadrants comprise a first quadrant, a second quadrant, a third quadrant and a fourth quadrant;

wherein, as shown in fig. 2, when the electro-hydrostatic actuator capable of overcoming the overrunning load is operated in the first quadrant, the direction of the external load force is towards the left, the speed direction of the hydraulic cylinder 12 is opposite to the direction of the external load force, the speed regulating motor 1 rotates anticlockwise to drive a first oil port of the bidirectional hydraulic pump 2 to discharge high-pressure oil, the high-pressure oil sequentially flows through a first input end and a first output end of the bidirectional hydraulic lock 10 and then flows to a rodless cavity of the hydraulic cylinder 12, the external load force pushes a piston of the hydraulic cylinder 12 to move so that a rod cavity of the hydraulic cylinder 12 discharges oil outwards, the discharged oil flows through a second output end of the bidirectional hydraulic lock 10, because the pressure of the second hydraulic control end is introduced from the first input end as high pressure, the second output end is reversely conducted with the second input end, the return oil of the rod cavity of the hydraulic cylinder 12 returns to the oil tank 3 through the second proportional overflow valve 8, and the first oil port of the bidirectional hydraulic pump 2 sucks oil from the oil tank 3 through the second oil-supplementing one-way valve 5; when the electro-hydrostatic actuator capable of overcoming the overload works in the first quadrant, the set pressure of the first proportional overflow valve 6 is larger than the external load force, so that the hydraulic cylinder 12 can overcome the external load force and all oil discharged by the bidirectional hydraulic pump 2 enters a rodless cavity of the hydraulic cylinder 12, and the set pressure of the second proportional overflow valve 8 is in an unloading state, so that the pressure of a rod cavity of the hydraulic cylinder 12 is close to zero pressure, and the energy consumption of the system is further reduced.

Wherein, as shown in fig. 3, when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the second quadrant, the direction of the external load force is towards the right, the speed direction of the hydraulic cylinder 12 is the same as the direction of the external load force, the governor motor 1 rotates counterclockwise to drive the first oil port of the bidirectional hydraulic pump 2 to discharge oil, the oil flows through the first input end and the first output end of the bidirectional hydraulic lock 10 to the rodless cavity of the hydraulic cylinder 12 in sequence, the external load force pushes the piston of the hydraulic cylinder 12 to move so that the rod cavity of the hydraulic cylinder 12 discharges oil outwards, the rod cavity of the hydraulic cylinder 12 is a high-pressure cavity and flows through the second output end of the bidirectional hydraulic lock 10, the set pressure of the second proportional pressure regulating valve is set to be greater than the external load force so that low-pressure exists in the rodless cavity of the hydraulic cylinder 12, the first pressure sensor 9 detects the pressures of the first input end and the second hydraulic control end of the bidirectional hydraulic lock 10, so that the second output end can be conducted to the second input end in the reverse direction, high-pressure return oil of a rod cavity of the hydraulic cylinder 12 returns to the oil tank 3 through the second proportional overflow valve 8, and a first oil port of the bidirectional hydraulic pump 2 absorbs oil from the oil tank 3 through the second oil-supplementing one-way valve 5; the set pressure of the first proportional overflow valve 6 is greater than the reverse opening pressure of the hydraulic control end of the bidirectional hydraulic lock 10, so that the oil discharged from the bidirectional hydraulic lock 10 completely enters the rodless cavity of the hydraulic cylinder 12, and the running speed of the electro-hydrostatic actuator capable of overcoming the overrunning load is further increased; the high pressure in the rod chamber of the hydraulic cylinder 12 is used to balance the external load force and the pressure in the rodless chamber of the hydraulic cylinder 12, ensuring that the electro-hydrostatic actuator which can overcome the overrunning load can work stably under the overrunning load.

As shown in fig. 4, when the electro-hydrostatic actuator capable of overcoming the overload works in the third quadrant, the direction of the external load force is towards the right, the speed direction of the hydraulic cylinder 12 is opposite to the direction of the external load force, the speed regulating motor 1 rotates clockwise to drive the second oil port of the bidirectional hydraulic pump 2 to discharge high-pressure oil, the high-pressure oil sequentially flows through the loop check valve 7, the second input end and the second output end of the bidirectional hydraulic lock 10 to the rod cavity of the hydraulic cylinder 12, the external load force pushes the piston of the hydraulic cylinder 12 to move so that the rodless cavity of the hydraulic cylinder 12 discharges oil outwards and flows through the first output end of the bidirectional hydraulic lock 10, because the pressure of the first hydraulic control end is introduced from the second input end as high pressure, the first output end and the first input end are reversely conducted, and the oil return part of the rodless cavity of the hydraulic cylinder 12 enters the first oil port of the bidirectional hydraulic pump 2; when the electro-hydrostatic actuator capable of overcoming the overload works in the third quadrant, the set pressure of the first proportional overflow valve 6 is in an unloading state, so that the pressure of a rodless cavity of the hydraulic cylinder 12 is close to zero pressure, and the pressure of a rod cavity of the hydraulic cylinder 12 is reduced; the set pressure of the second proportional relief valve 8 is greater than the external load force, so that the hydraulic cylinder 12 can overcome the external load force and the oil discharged from the bidirectional hydraulic pump 2 can completely enter the rod cavity of the hydraulic cylinder 12, and the system efficiency is further improved.

As shown in fig. 5, when the electro-hydrostatic actuator capable of overcoming the overrunning load works in the fourth quadrant, the direction of the external load force faces to the left, the speed direction of the hydraulic cylinder 12 is the same as the direction of the external load force, the speed regulating motor 1 rotates clockwise to drive the second oil port of the bidirectional hydraulic pump 2 to discharge oil, the oil flows through the loop check valve 7, the second input end and the second output end of the bidirectional hydraulic lock 10 to the rod cavity of the hydraulic cylinder 12 in sequence, the external load force pushes the piston of the hydraulic cylinder 12 to move so that the rodless cavity of the hydraulic pump discharges oil outwards, and the oil flows through the first output end and the first input end of the bidirectional hydraulic lock 10 in sequence and then enters the second oil port of the bidirectional hydraulic pump 2; the hydraulic cylinder 12 is a single-rod asymmetric hydraulic cylinder 12, the oil return amount of a rodless cavity in the hydraulic cylinder 12 is larger than the oil inlet amount of a rod cavity, can overcome the defect that when the electro-hydrostatic actuator of the overrunning load works in the fourth quadrant, the pressure of the second proportional overflow valve 8 is set to be larger than the reverse opening pressure of the hydraulic control end of the bidirectional hydraulic lock 10, the pressure of the first input end and the second hydraulic control end of the bidirectional hydraulic lock 10 is detected by the second pressure sensor 11, so that the first output end and the first input end of the bidirectional hydraulic lock 10 are conducted in reverse direction, meanwhile, the set pressure of the first proportional overflow valve 6 is set to be larger than the external load pressure, so that all return oil of the rodless cavity of the hydraulic cylinder 12 enters the first oil port of the bidirectional hydraulic pump 2, the return oil quantity of the rodless cavity of the hydraulic cylinder 12 is equal to the product of the displacement of the bidirectional hydraulic pump 2 and the rotating speed of the motor, and the differential flow of the rodless cavity and the rod cavity of the bidirectional hydraulic cylinder 12 overflows to return oil through the second proportional overflow valve 8; the first oil port of the bidirectional hydraulic pump 2 is a high-pressure side oil port, and the second oil port of the bidirectional hydraulic pump 2 is a low-pressure side oil port, so that torque required by clockwise rotation of the speed regulating motor 1 can be effectively reduced, and the energy efficiency of the system is improved; the rodless chamber high pressure of the hydraulic cylinder 12 is used to balance the external load force and the rod chamber pressure to ensure that the electro-hydrostatic actuator that can overcome the overrunning load can work stably under the overrunning load.

The electro-hydrostatic actuator capable of overcoming the overrunning load in the invention can respectively realize closed-loop control on the force, speed or displacement output by the actuator. Specifically, when the output of the electro-hydrostatic actuator capable of overcoming the overrunning load is force, the electro-hydrostatic actuator can accurately control the magnitude or the output direction of the output force, and can also realize similar control on displacement and speed. According to the invention, the output force control of the actuator can be realized through the set pressure of the first proportional overflow valve 6 and the second proportional overflow valve 8, the speed of the actuator can be calculated through the differential of the displacement signal fed back by the displacement sensor 13, the speed closed-loop control can be realized by controlling the rotation speed of the speed regulating motor 1, the position accurate positioning of the actuator can be realized by controlling the power-on and power-off of the speed regulating motor 1 through the feedback of the displacement signal of the displacement sensor 13, and the position maintenance of the actuator can be realized through the locking function of the bidirectional hydraulic lock 10.

In summary, the electro-hydrostatic actuator capable of overcoming the overload in the invention can perform accurate position maintenance when the speed regulating motor 1 is powered off and an external load exists, effectively reduce the energy consumption of the system, stably work in four working quadrants, reduce the pressure loss of the system by setting the set pressure of the first proportional overflow valve 6 and the second proportional overflow valve 8, and effectively improve the energy efficiency of the system.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.