CN104728193B - The Electrical hydrostatic actuator of load-sensitive - Google Patents

Abstract

The invention relates to a load-sensitive electric hydrostatic actuator, which includes a variable-displacement hydraulic pump, a first series switch group, an asymmetrical hydraulic cylinder, a pressure-following servo valve and an actuator. A variable displacement hydraulic pump includes an oil inlet and an oil outlet. The first series switch group includes a first switch valve and a second switch valve connected in series. The asymmetric hydraulic cylinder includes a casing and a first asymmetric piston, and the casing is divided into a first rod chamber and a first rodless chamber by the first asymmetric piston. The pressure-following servo valve is connected between the first rod chamber of the asymmetric hydraulic cylinder and the input end of the actuator. The input end of the actuator is connected with the output end of the pressure servo valve. By adopting the load-sensitive electric hydrostatic actuator of the present invention, the output flow of the variable-displacement hydraulic pump can be quantitatively adjusted by controlling the output hydraulic pressure of the pressure-following servo valve, thereby reducing heat dissipation and power consumption of the entire system.

Description

Load Sensitive Electrohydrostatic Actuators

technical field

The invention relates to the field of electric hydrostatic actuators, in particular to a load-sensitive electric hydrostatic actuator.

Background technique

EHA (Electro-Hydrostatic Actuator) is a highly integrated partial hydraulic actuator, which is the actuator of the power fly-by-wire actuation system in multi-electric aircraft. Compared with the traditional hydraulic actuating system, EHA has the advantages of small size, light weight, high efficiency, etc., and it is a hot spot of current research. By adopting the load sensitive method, energy loss can be reduced and the heating of the motor can be reduced.

At present, the electric hydrostatic actuator with constant displacement and variable speed is widely used in the power fly-by-wire actuation system of aircraft in the world. Its advantages are simple structure and light weight. However, due to the highly integrated design, it is difficult to dissipate heat from the system; under heavy load, the efficiency of the motor is low, the current is large, and the heat is severe, which makes the EHA unable to work for a long time.

The current solution is to consider the heat dissipation of the system at the beginning of the system design; the second is to use a variable displacement pump to change the transmission ratio of the system by changing the displacement of the pump, thereby improving the power matching of the motor and reducing the power consumption of the system. of calorific value. The variable actuators of the variable pump mostly use servo valves to control the hydraulic cylinder to drive the variable mechanism of the pump to achieve variable displacement, or use electromechanical actuators (EMA) to drive the variable mechanism of the pump to achieve variable displacement; the structure comparison of these two methods Complexity increases the system failure rate.

Due to the low power loss of the load-sensing control system, the efficiency is much higher than that of the conventional hydraulic system; high efficiency and low power loss mean fuel saving and low calorific value of the hydraulic system; therefore, some research institutions have introduced load-sensing methods into EHA . However, most of the existing load-sensitive EHAs use servo valves for commutation and control, and servo valves will generate a lot of heat during operation, which is not conducive to reducing the heat generation of the system.

Contents of the invention

A brief overview of the invention is given below in order to provide a basic understanding of some aspects of the invention. It should be understood that this summary is not an exhaustive overview of the invention. It is not intended to identify key or critical parts of the invention nor to delineate the scope of the invention. Its purpose is merely to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

A main purpose of the present invention is to provide a new load-sensitive electrohydrostatic actuator, which can reduce heat generation and energy loss of the entire system, thereby improving the working efficiency of the entire system.

According to one aspect of the present invention, a load-sensitive electrohydrostatic actuator includes a variable-displacement hydraulic pump, a first series switch group, an asymmetric hydraulic cylinder, a pressure-following servo valve, and an actuator;

The variable displacement hydraulic pump includes an oil inlet and an oil outlet;

The first series switch group includes a first switch valve and a second switch valve connected in series, the first end of the first switch valve is connected to the oil outlet, the first end of the second switch valve is connected to the inlet Oil port connection;

The asymmetric hydraulic cylinder includes a housing and a first asymmetric piston, the housing is divided into a first rod chamber and a first rodless chamber by the first asymmetric piston, and the first rod chamber is connected to To the second end of the first switch valve and the second end of the second switch valve, the first rodless cavity is connected to the oil inlet;

The pressure-following servo valve is connected between the first rod chamber of the asymmetric hydraulic cylinder and the input end of the actuator, and is used to adjust the instantaneous flow input to the input end of the actuator;

The input end of the actuator is connected to the output end of the pressure servo valve, and is used for generating a signal for changing the output displacement of the variable displacement hydraulic pump based on the output hydraulic pressure of the pressure servo valve.

By adopting the load-sensitive electric hydrostatic actuator of the present invention, the heating of the system can be reduced, and the energy loss can be reduced.

Description of drawings

The above and other objects, features and advantages of the present invention will be more easily understood with reference to the following description of the embodiments of the present invention in conjunction with the accompanying drawings. The components in the drawings are only to illustrate the principles of the invention. In the drawings, the same or similar technical features or components will be denoted by the same or similar reference numerals.

Fig. 1 is a structural diagram of an embodiment of the load-sensitive electrohydrostatic actuator of the present invention;

Fig. 2 is a structural diagram of an embodiment of the pressure-following servo valve in Fig. 1;

Fig. 3 is a schematic diagram when the spool of the pressure-following servo valve in Fig. 2 is in the left position;

Fig. 4 is a schematic diagram when the spool of the pressure-following servo valve in Fig. 2 is in the right position;

Fig. 5 is a schematic diagram of liquid flow when the load-sensitive electrohydrostatic actuator of Fig. 1 works in the first quadrant and the second quadrant;

FIG. 6 is a schematic diagram of liquid flow when the load-sensitive electrohydrostatic actuator of FIG. 1 works in the third quadrant and the fourth quadrant.

detailed description

Embodiments of the present invention will be described below with reference to the drawings. Elements and features described in one drawing or one embodiment of the present invention may be combined with elements and features shown in one or more other drawings or embodiments. It should be noted that representation and description of components and processes that are not related to the present invention and known to those of ordinary skill in the art are omitted from the drawings and descriptions for the purpose of clarity.

Referring to FIG. 1 , it is a structural diagram of an embodiment of the load-sensitive electrohydrostatic actuator of the present invention.

In this embodiment, the load-sensitive electric hydrostatic actuator includes a variable displacement hydraulic pump 2 , a first series switch group, an asymmetric hydraulic cylinder 9 , a pressure-following servo valve 10 and an actuator 4 .

Wherein, the variable displacement hydraulic pump 2 includes an oil inlet and an oil outlet. In specific use, the oil inlet and the oil outlet of the variable displacement hydraulic pump 2 can perform oil suction and oil discharge according to actual needs.

The first series switch group includes a first switch valve 7 and a second switch valve 8 connected in series. The first end of the first on-off valve 7 is connected to the oil outlet, and the first end of the second on-off valve 8 is connected to the oil inlet.

The asymmetrical hydraulic cylinder 9 comprises a housing and a first asymmetrical piston. The housing is divided into a first rod chamber and a first rodless chamber by the first asymmetric piston. The first rod chamber is connected to the second end of the first switching valve 7 and the second end of the second switching valve 8. The second A rodless chamber is connected to the oil inlet. The column of the first asymmetrical piston is externally connected to a load, and is used to drive the load to perform related actions, or to move up and down driven by the load.

The pressure-following servo valve 10 is connected between the first rod chamber of the asymmetric hydraulic cylinder 9 and the input end of the actuator 4 for adjusting the instantaneous flow input to the input end of the actuator 4 .

The input end of the actuator is connected with the output end of the pressure servo valve, and is used to generate a signal for changing the output displacement of the variable displacement hydraulic pump 2 based on the output hydraulic pressure of the pressure servo valve.

The load sensitive electrohydrostatic actuator of this embodiment further includes a second series switch group and an oil tank 3 .

The second series switch group is connected between the oil inlet port and the oil outlet port of the variable displacement hydraulic pump 2, and is connected with the oil tank 3, and is used for inputting the oil in the oil tank 3 into the asymmetric hydraulic cylinder 9 or transferring the asymmetric hydraulic cylinder The oil in 9 is drained into tank 3.

In one embodiment, the second series switch group may include a first hydraulically controlled one-way valve 5 and a second hydraulically controlled one-way valve 6 connected in series.

The first hydraulic control check valve 5 includes a first hydraulic control terminal, a first input terminal and a first output terminal. The first liquid control end is connected with the oil inlet, the first input end is connected with the oil outlet, and the first output end is connected with the oil tank 3 . Since the first hydraulic control end is connected to the oil inlet, when the oil inlet is under high pressure, the first hydraulic control check valve 5 is opened.

The second hydraulic control check valve 6 includes a second hydraulic control terminal, a second input terminal and a second output terminal. The second liquid control end is connected with the oil outlet, the second input end is connected with the oil inlet, and the second output end is connected with the oil tank 3 . Since the second hydraulic control end is connected to the oil outlet, when the oil outlet is under high pressure, the second hydraulic control check valve 6 is opened.

The first asymmetrical piston may include a first plug portion and a first column fixedly connected to one side of the first plug portion and perpendicular to the first plug portion.

As a preferred solution, the cross-sectional area of the first plug part is twice the cross-sectional area of the first column part.

In one embodiment, the actuator 4 may be a single-acting hydraulic cylinder.

The single-acting hydraulic cylinder may include a cylinder body, a second asymmetric piston, and a first spring located in the cylinder body. The second asymmetric piston includes a second column portion and a second plug portion perpendicular to each other. The second plug cooperates with the inner wall of the cylinder to form a second cavity containing an inlet connected to the first rod cavity.

The first spring is arranged in the third cavity of the single-acting hydraulic cylinder including the second column, the elastic direction of the first spring coincides with the axis of the second column, and the first spring works in a non-tensioned state.

One end of the second column is fixedly connected to the second plug, and the other end of the second column is connected to the variable displacement hydraulic pump, which is used to press the second plug according to the pressure of the liquid entering the second cavity and the first spring. The resultant force of the pressure of the second plug changes the output displacement of the variable displacement hydraulic pump.

In this embodiment, the variable displacement hydraulic pump 2 includes a swash plate, and the output flow of the variable displacement hydraulic pump 2 is positively related to the inclination angle of the swash plate. That is to say, the greater the inclination angle of the swash plate, the greater the output flow of the variable displacement hydraulic pump 2 .

The second column of the single-acting hydraulic cylinder is connected to the swash plate of the variable displacement hydraulic pump, and is used to change the output flow of the variable displacement hydraulic pump 2 by changing the inclination angle of the swash plate.

Since the single-acting hydraulic cylinder is connected to the first rod chamber of the asymmetric hydraulic cylinder 9, it can be sensitive to the hydraulic pressure in the first rod chamber, and push the second asymmetric piston of the single-acting hydraulic cylinder to the left, thereby changing the displacement Measure the inclination angle of the swash plate of hydraulic pump 2.

In addition, the load-sensitive electric hydrostatic actuator also includes a speed-adjustable motor 1 . The speed regulating motor 1 is connected with the variable displacement hydraulic pump 2 for driving the variable displacement hydraulic pump 2 .

For example, when the single-acting hydraulic cylinder pushes the swash plate of the variable displacement hydraulic pump 2 to reduce its inclination angle, if you want to keep the output power to the load connected to the asymmetric hydraulic cylinder 9 unchanged at the same time, you can increase the adjustment. Speed motor 1 speed. The power output to the load can be kept constant by increasing the rotational speed of the motor 1 . In this way, the output torque of the motor is reduced, so its current is reduced, which in turn reduces the copper loss and heat generation of the motor.

Referring to FIG. 2 , it is a structural diagram of an embodiment of the pressure-following servo valve in the load-sensitive electrohydrostatic actuator of the present invention.

In this embodiment, the pressure-following servo valve includes a housing 150 , a valve core inside the housing 150 and a first decompression half-bridge 130 .

Wherein, the valve core is an asymmetric plunger, including a third column portion 151 protruding out of the casing 150 and a third plug portion fixedly connected with the third column portion 151 and located in the casing 150 .

The third plug part is provided with a circumferential groove, and the circumferential groove divides the third plug part into a first plug body 152 and a second plug body 153 . The first plug body 152 and the second plug body 153 form a clearance fit with the housing 150 .

The valve core divides the housing 150 into a third rod chamber including the third column portion 151 , an intermediate chamber located between the first plug body 152 and the second plug body 153 , and a third rodless chamber.

The casing 15 is provided with a first inlet 154 , a second inlet 155 and a third inlet 156 .

The first inlet 154 is connected to the first rod cavity of the asymmetric hydraulic cylinder 9 for receiving the hydraulic pressure input of the first rod cavity, and the second inlet 155 is connected to the external oil tank T. In this way, the pressure-following servo valve of the present invention can discharge excess oil to the external oil tank T through the second inlet 355 .

The first inlet 154 is also connected with the first end of the first decompression half bridge 130, the second inlet 155 is also connected with the second end of the first decompression half bridge 130, and the third inlet 156 is connected with the first decompression half bridge 130 The middle end of the connection is used to input the external hydraulic pressure (that is, the hydraulic pressure from the first rod chamber) to the third rodless chamber after partial pressure.

The housing 150 is also provided with an outlet 157 and a feedback port 158, the outlet 157 is connected to the input end of the actuator 4, and the feedback port 158 is used to hydraulically feed the outlet 157 to the third rod chamber.

In one embodiment, the first decompression half-bridge 130 may include a first orifice 13 and a second orifice 14 connected in series. The first inlet 154 may be connected to a first end of the first orifice 13 , and the third inlet 156 may be connected to a second end of the first orifice 13 and a first end of the second orifice 14 . The second inlet 155 is connected to the second end of the second orifice 14 . That is to say, since the second inlet 155 and the second throttle hole 14 are connected to the external oil tank T at the same time, the oil pressure at the second end of the second inlet 155 and the second throttle hole 14 is zero.

In another embodiment, the pressure-following servo valve 10 may further include a second decompression half-bridge 170 .

The second decompression half-bridge 170 may include a third orifice 17 and a fourth orifice 18 connected in series. The first end of the third orifice 17 may be connected with the outlet 157 . The second end of the third orifice 17 is connected to the first end of the fourth orifice 18 and the feedback port 158 . The second end of the fourth orifice 18 is connected to the external oil tank T, so that the oil pressure at the second end of the fourth orifice 18 is zero.

The pressure-following servo valve 10 also includes a power unit 11 . The power device 11 is used to apply an axial force along the axial direction of the spool to the third column portion 151 , and adjust the output hydraulic pressure at the outlet based on the axial force.

In one embodiment, the power device 11 may be, for example, a proportional electromagnet or a voice coil motor.

As a preferred solution, the pressure-following servo valve 10 may further include a second spring 12 disposed in the third rod-bearing chamber and a third spring 16 disposed in the third rod-free chamber. The elastic force directions of the second spring 12 and the third spring 16 coincide with the axis of the valve core, and the second spring 12 and the third spring 16 work in a non-stretched state.

Assume that the thrust of the power device 11 is F _M , and the resultant force of the second spring 12 and the third spring 16 is F _K . In the case of ignoring the hydraulic force, the steady-state equilibrium has:

F _M -F _K ＝P _s 'S ₁ -P _A 'S ₂ ＝P _s S ₁ /K ₁ -P _A S ₂ /K ₂ ,

Wherein, S ₁ and _{S 2} are the action areas of PS ′ and PA ′ respectively, that is, _S 1 is the cross-sectional area of the second plug body 153 in the third rodless chamber, and S ₂ is the first plug in the third rodless chamber. The difference between the sectional area of the body 152 and the sectional area of the third column portion 151; K ₁ is the decompression ratio of the first half-bridge 130, and K ₂ is the decompression ratio of the second half-bridge 170.

Since the displacement of the spool is very small, the spring force can also be ignored. If there is S ₁ /K ₁ =S ₂ /K ₂ , the steady-state balance is:

F _M =P _s S ₁ /K ₁ -P _A S ₂ /K ₂ =(P _s -P _A )S ₁ /K ₁ =(P _s -P _A )S ₂ /K ₂

When the thrust F _M of the power unit 1 is set, the pressure difference between the inlet and outlet P _S -PA can be approximately controlled, and then the oil pressure P _A at the outlet of the valve can be controlled _.

As an optimal solution, due to the asymmetry of the action areas at both ends of the spool, the inlet and outlet pressure difference P _{S -PA is not proportional to the thrust F M of} the power device 11, which increases the difficulty of control. To make up for this asymmetrical force, the difference in the decompression ratio between the first decompression half-bridge 130 and the second decompression half-bridge 170 can be set so that when P _S and P _A are equal, there is P _S 'S ₁ -P _A 'S ₂ =0.

Since the first decompression half-bridge 130 reduces the oil pressure input into the casing, the power unit 11 can control the oil pressure PA of the outlet 157 to _a preset value with only a small output force. Therefore, the volume of the entire pressure-following servo valve 10 can be reduced

FIG. 3 is a schematic diagram of the pressure-following servo valve spool in FIG. 2 when it is in the left position, and FIG. 4 is a schematic diagram when the pressure-following servo valve spool in FIG. 2 is in the right position.

The working state of the pressure-following servo valve of this embodiment will be described below with reference to FIGS. 2-4 .

When the pressure-following servo valve starts to work, its spool is in the neutral position, as shown in Fig. 2 .

When the output oil pressure P _A is required to be a predetermined value, the predetermined value P _A can be achieved by adjusting the output thrust of the power device 11 .

Assuming that under the action of thrust F _M and the resultant force F _K of the second spring 12 and the third spring 16, the spool moves to the left position (as shown in Figure 3), at this time the outlet 157 communicates with the external oil tank T, and the oil in the outlet 157 The pressure P _A will decrease, and at the same time, the oil pressure P _A ' of the feedback port 158 will also decrease, resulting in a decrease of the rightward force acting on the first plug body 152 in the third rod chamber, and the spool moves to the right.

When the spool is pushed to the right position as shown in Figure 4, the outlet 157 communicates with the first inlet 154, and the oil pressure P _A of the outlet 157 will increase, and at the same time, the oil pressure P _A ' of the feedback port 158 will also increase, As a result, the leftward force acting on the first plug body 152 in the third rod chamber increases, and the spool moves leftward.

Through the above adjustment process, the spool will finally stabilize at a position where the outlet oil pressure P _A is equal to the preset value.

It can be seen from the above description that by setting the thrust of the power unit 11, the oil pressure PA of the _inlet and outlet 157 can be controlled. If the oil pressure P _A at the outlet 157 is higher than the set value, the spool moves to the right, and the oil pressure P _A at the outlet 157 decreases until a balance is maintained. Similarly, if the oil pressure PA at the outlet ₁₅₇ is lower than the set value, the spool moves to the left, and the oil pressure PA at the outlet ₁₅₇ increases until the balance is maintained.

In this way, the output force of the actuator 11 can be adjusted quantitatively, and then the inclination angle of the swash plate of the variable displacement hydraulic pump 2 can be adjusted quantitatively.

FIG. 5 is a schematic diagram of liquid flow when the load-sensitive electrohydrostatic actuator of FIG. 1 works in the first quadrant and the second quadrant. The solid arrows in Fig. 5 represent the liquid flow direction when the load-sensitive electrohydrostatic actuator works in the first quadrant; the hollow arrows in Fig. 5 represent the fluid flow direction when the load-sensitive electrohydrostatic actuator works in the second quadrant direction of liquid flow.

FIG. 6 is a schematic diagram of liquid flow when the load-sensitive electrohydrostatic actuator of FIG. 1 works in the third quadrant and the fourth quadrant. The solid arrows in Fig. 6 represent the liquid flow direction when the load-sensitive electrohydrostatic actuator works in the third quadrant; the hollow arrows in Fig. 6 represent the fluid flow direction when the load-sensitive electrohydrostatic actuator works in the fourth quadrant direction of liquid flow.

When the load-sensitive electric hydrostatic actuator of the present invention works in the first quadrant, the speed-regulating motor 1 drives the variable-displacement hydraulic pump 2 to rotate, and the high-pressure oil flows from the upper end (ie, the oil outlet) of the variable-displacement hydraulic pump 2 output, the first on-off valve 7 works in the on state, the second on-off valve 8 works in the off state, the output force and movement speed of the first asymmetric piston of the asymmetric hydraulic cylinder 9 are both downward, and the second hydraulic control check valve 6 Because the high pressure of the upper oil circuit is in the open state, part of the oil in the first rodless chamber enters the oil inlet of the variable displacement hydraulic pump 2, and part returns to the oil tank 3.

When the load-sensitive electric hydrostatic actuator of the present invention works in the second quadrant, the asymmetric hydraulic cylinder 9 is subjected to a parallel load, the output force of the first asymmetric piston is downward, and the movement speed is upward, and the variable displacement hydraulic pressure Pump 2 works under motor condition. The speed-regulating motor 1 works in the generator working condition, the first on-off valve 7 works in the on state, and the second on-off valve 8 works in the off state. The second hydraulically controlled one-way valve 6 is in an open state, part of the oil entering the first rodless chamber flows in through the variable displacement hydraulic pump 2 , and part of it is replenished through the oil tank 3 .

When the load-sensitive electric hydrostatic actuator of the present invention works in the third quadrant, that is, the speed-regulating motor 1 drives the variable displacement pump to rotate in reverse, and the high-pressure oil is output from the lower end of the pump (that is, the oil inlet), and the first switch valve 7 works in the off state, the second on-off valve 8 works in the on state, the output force and the movement speed of the first asymmetric piston of the asymmetric hydraulic cylinder 9 are both upward, and the first hydraulic control check valve 5 is High voltage is on. The oil in the first rod chamber enters the first rodless chamber through the oil passage, and the rest of the oil is sucked from the oil tank 3 by the variable displacement hydraulic pump 2 and input into the first rodless chamber.

When the load-sensitive electric hydrostatic actuator of the present invention works in the fourth quadrant, the asymmetric hydraulic cylinder 9 is subjected to a parallel load, the output force of the first asymmetric piston is upward, and the movement speed is downward, and the variable displacement hydraulic pump 2. Working in the motor condition, the speed regulating motor 1 works in the generator working condition, the first on-off valve 7 works in the cut-off state, and the second on-off valve 8 works in the on-state, and the first hydraulic control check valve 5 is in the open state state, a part of the oil in the first rodless chamber flows into the first rod chamber, and the excess oil returns to the oil tank 3 through the variable displacement hydraulic pump 2 .

Since the effective working area of the first rod chamber and the first rodless chamber of the asymmetrical cylinder 9 is 1:2, and the actuator of the asymmetrical hydraulic cylinder 9 works in the third and fourth quadrants, it adopts differential drive, that is to say , the high-pressure oil communicates with the first rod chamber and the first rodless chamber of the asymmetric hydraulic cylinder 9 at the same time. Due to the area difference between the first rod chamber and the first rodless chamber, under the same pressure, the first rodless chamber The force is greater than the first rod chamber, pushing the piston rod of the asymmetric hydraulic cylinder 9 to move. When the output pressure of the displacement hydraulic pump 2 is constant, the output forces of the actuators in the first and third quadrants are equal and opposite. In this way, the control asymmetry of the asymmetric hydraulic cylinder 9 can be overcome, and the same control and output characteristics as the symmetrical hydraulic cylinder can be obtained.

In addition, the selection of the power of the speed-regulating motor 1 is no longer determined by the maximum flow rate of the first rodless chamber of the asymmetric hydraulic cylinder. That is, the power of the motor is reduced by half compared with before, which reduces the weight of the system and improves the energy utilization rate. Specifically, due to the area difference between the first rod chamber and the first rodless chamber of the asymmetrical hydraulic cylinder 9, when the high-pressure oil acts on the first rod chamber and the first rodless chamber respectively, under the same flow rate , when the high-pressure oil acts on the first rod chamber than when it acts on the first rodless chamber, the movement speed of the first asymmetrical piston is greater. In order for the high-pressure oil to act on the first rodless chamber, the movement speed of the first asymmetrical piston reaches the maximum movement speed of the electric hydrostatic actuator, the maximum movement speed of the system needs to be calculated according to the maximum movement speed of the first rodless chamber. The flow is used to select the power of the speed regulating motor. According to the characteristics of this system, the area ratio of the first rod chamber and the first rodless chamber is 1:2. If the differential drive is not used, the power, speed and rated current of the speed regulating motor will be driven by the differential drive. double. In addition, after adopting the differential drive, the weight of the speed regulating motor and the volume of the motor will also be significantly reduced.

In the four-quadrant operation of the load-sensitive electrohydrostatic actuator of the present invention, it can be seen from the working characteristics of the oil circuit that the first rod chamber is always in a high-pressure working condition, and because the first rod chamber and the first rodless The effective working area of the cavity is 1:2, and the pressure of the first rod cavity directly reflects the output force of the actuator, so the pressure of the first rod cavity is directly used as the input end of the single-acting hydraulic cylinder. When the load pressure increases, the pressure in the first rod chamber increases accordingly, and the second asymmetric piston of the single-acting hydraulic cylinder moves to the left, the inclination angle of the swash plate of the variable displacement hydraulic pump 2 becomes smaller, and the displacement decreases. small. At the same time, in order to maintain the flow required by the load, the output flow of the variable displacement hydraulic pump 2 can be increased by increasing the speed of the speed regulating motor 1, thereby increasing the output flow to the load. In this way, the heat generation of the speed regulating motor 1 can be reduced, and the working efficiency thereof can be improved.

In addition, the outlet pressure Pa of the pressure-following servo valve can be controlled by adjusting the output force of the power device of the pressure-following servo valve 10, and then the swash plate inclination angle and output flow of the variable displacement hydraulic pump 2 can be quantitatively controlled.

The load-sensitive electric hydrostatic actuator of the invention can realize the control of the output force, displacement or speed of the actuator. Specifically, the electrohydrostatic actuator of the present invention can output parameters such as force, displacement, and velocity, and the electrohydrostatic actuator can separately control the output force, displacement, and velocity. That is to say, when the output of the electrohydrostatic actuator is force, it can accurately control the magnitude and direction of the output force; similar control can be achieved for displacement and speed.

By adopting the load-sensitive electric hydrostatic actuator of the present invention, the output flow of the variable-displacement hydraulic pump can be quantitatively adjusted by controlling the output hydraulic pressure of the pressure-following servo valve, thereby reducing heat dissipation and power consumption of the entire system.

Some embodiments of the present invention have been described in detail above. As can be understood by those of ordinary skill in the art, all or any steps or components of the method and apparatus of the present invention can be implemented in any computing device (including processor, storage medium, etc.) or network of computing devices in the form of hardware, It can be realized by firmware, software or their combination, which can be realized by those skilled in the art by using their basic programming skills after understanding the content of the present invention, so no specific description is needed here.

Furthermore, it is obvious that any display device and any input device connected to any computing device, corresponding interfaces and control programs are undoubtedly used when the above description refers to possible external operations. In a word, the relevant hardware, software in the computer, computer system or computer network, and the hardware, firmware, software or their combination to realize various operations in the aforementioned method of the present invention constitute the device and its component parts of the present invention.

Therefore, based on the above understanding, the object of the present invention can also be realized by running a program or a group of programs on any information processing device. The information processing device may be a known general-purpose device. Therefore, the object of the present invention can also be achieved only by providing a program product including program codes for realizing the method or device. That is, such a program product also constitutes the present invention, and a medium storing or transmitting such a program product also constitutes the present invention. Apparently, the storage or transmission medium may be any type of storage or transmission medium known to those skilled in the art or developed in the future, so it is not necessary to list all kinds of storage or transmission media here.

In the device and method of the present invention, obviously, each component or each step can be decomposed, combined and/or recombined after decomposing. These decompositions and/or recombinations should be considered equivalents of the present invention. It should also be pointed out that the steps for executing the above series of processes can naturally be executed in chronological order according to the illustrated order, but it does not need to be executed in chronological order. Certain steps may be performed in parallel or independently of each other. Meanwhile, in the above descriptions of specific embodiments of the present invention, features described and/or shown for one embodiment can be used in one or more other embodiments in the same or similar manner, and combination of features, or replace features in other embodiments.

It should be emphasized that the term "comprising/comprising" when used herein refers to the presence of a feature, element, step or component, but does not exclude the presence or addition of one or more other features, elements, steps or components.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not limited to the specific embodiments of the procedures, devices, means, methods and steps described in the specification. Those of ordinary skill in the art will readily appreciate from the disclosure of the present invention that existing and future devices that perform substantially the same function or obtain substantially the same results as the corresponding embodiments described herein can be used in accordance with the present invention. The developed process, device, means, method or steps. Accordingly, the appended claims are intended to include within their scope such processes, means, means, methods or steps.

Claims (14)

1. A load-sensitive electric hydrostatic actuator, characterized in that it comprises a variable-displacement hydraulic pump, a first series switch group, an asymmetric hydraulic cylinder, a pressure-following servo valve, and an actuator; The variable displacement hydraulic pump includes an oil inlet and an oil outlet; The first series switch group includes a first switch valve and a second switch valve connected in series, the first end of the first switch valve is connected to the oil outlet, the first end of the second switch valve is connected to the inlet Oil port connection; The asymmetric hydraulic cylinder includes a housing and a first asymmetric piston, the housing is divided into a first rod chamber and a first rodless chamber by the first asymmetric piston, and the first rod chamber is connected to To the second end of the first switch valve and the second end of the second switch valve, the first rodless chamber is connected to the oil inlet; The pressure-following servo valve is connected between the first rod chamber of the asymmetric hydraulic cylinder and the input end of the actuator, and is used to adjust the instantaneous flow input to the input end of the actuator; The input end of the actuator is connected with the output end of the pressure servo valve, and is used for generating a signal for changing the output displacement of the variable displacement hydraulic pump based on the output hydraulic pressure of the pressure servo valve. 2. The load sensitive electrohydrostatic actuator according to claim 1, further comprising a second series switch group and an oil tank; The second series switch group is connected between the oil inlet port and the oil outlet port of the variable displacement hydraulic pump, and is connected with the oil tank, and is used to input the oil in the oil tank into the asymmetric hydraulic cylinder Or discharge the oil in the asymmetric hydraulic cylinder into the oil tank. 3. The load sensitive electrohydrostatic actuator according to claim 2, characterized in that: The second series switch group includes a first hydraulic control check valve and a second hydraulic control check valve connected in series; The first hydraulic control check valve includes a first hydraulic control port, a first input port and a first output port, the first hydraulic control port is connected to the oil inlet, and the first input port is connected to the The oil outlet is connected, and the first output end is connected to the oil tank; The second hydraulically controlled one-way valve includes a second hydraulically controlled port, a second input port and a second output port, the second hydraulically controlled port is connected to the oil outlet, and the second input port is connected to the The oil inlet is connected, and the second output end is connected with the oil tank. 4. The load sensitive electrohydrostatic actuator according to claim 3, characterized in that: The first asymmetric piston includes a first plug portion and a first column fixed to one side of the first plug portion and perpendicular to the first plug portion; The cross-sectional area of the first plug part is twice the cross-sectional area of the first column part. 5. The load sensitive electrohydrostatic actuator according to claim 4, characterized in that: The actuator is a single-acting hydraulic cylinder. 6. The load sensitive electrohydrostatic actuator according to claim 5, characterized in that: The single-acting hydraulic cylinder includes a cylinder body, a second asymmetric piston, and a first spring located in the cylinder body; The second asymmetric piston includes a second column portion and a second plug portion perpendicular to each other; said second plug cooperates with the inner wall of said cylinder to form a second cavity containing an inlet connected to said first rod cavity; The first spring is arranged in the third cavity of the single-acting hydraulic cylinder including the second column, the elastic force direction of the first spring coincides with the axis of the second column, and the first spring Work in a non-stretch state; One end of the second column part is fixedly connected to the second plug part, and the other end of the second column part is connected to the variable displacement hydraulic pump, which is used to adjust the pressure according to the liquid entering the second cavity. The output displacement of the variable displacement hydraulic pump is changed by the resultant force of the pressure of the second plug part and the pressure of the first spring on the second plug part. 7. The load sensitive electrohydrostatic actuator according to claim 6, characterized in that: The variable displacement hydraulic pump includes a swash plate, and the inclination angle of the swash plate is positively correlated with the output flow of the variable displacement hydraulic pump; The column part of the single-acting hydraulic cylinder is connected with the swash plate of the variable displacement hydraulic pump, and is used to change the output flow of the variable displacement hydraulic pump by changing the inclination angle of the swash plate. 8. The load sensitive electrohydrostatic actuator according to claim 7, characterized in that: Also includes speed-regulated motors; The speed regulating motor is connected with the variable displacement hydraulic pump for driving the variable displacement hydraulic pump. 9. The load-sensitive electrohydrostatic actuator according to any one of claims 1-8, wherein the pressure-following servo valve comprises a housing, a spool located in the housing, and a first decompression half bridge; in, The spool is an asymmetric plunger, including a third column protruding from the housing and a third plug fixedly connected with the third column and located in the housing, the third plug There is a circumferential groove, and the circumferential groove divides the third plug into a first plug body and a second plug body, and the first plug body and the second plug body form a clearance fit with the housing ; The valve core divides the housing into a third rod cavity containing the third column, an intermediate cavity between the first plug body and the second plug body, and a third rodless cavity. Rod cavity; The housing is provided with a first inlet, a second inlet and a third inlet; The first inlet is connected to the first rod cavity of the asymmetric cylinder, and the second inlet is connected to the external oil tank; The first inlet is also connected to the first end of the first decompression half-bridge, the second inlet is also connected to the second end of the first decompression half-bridge, and the third inlet is connected to the first end of the first decompression half-bridge. The middle end of the first decompression half-bridge is connected, and is used to input the hydraulic pressure of the first rod chamber to the third rodless chamber after partial pressure; The casing is also provided with an outlet and a feedback port, the outlet is connected to the input end of the actuator, and the feedback port is used to feed back the hydraulic pressure of the outlet to the third rod chamber. 10. The load sensitive electrohydrostatic actuator according to claim 9, characterized in that: The first decompression half-bridge includes a first orifice and a second orifice connected in series; the first inlet is connected to a first end of the first orifice; the third inlet is connected to the second end of the first orifice and the first end of the second orifice; The second inlet is connected to a second end of the second orifice. 11. The load sensitive electrohydrostatic actuator according to claim 10, characterized in that: The pressure-following servo valve also includes a second decompression half-bridge; The second decompression half-bridge includes a third orifice and a fourth orifice connected in series; The first end of the third orifice is connected to the outlet; The second end of the third orifice is connected to the first end of the fourth orifice and the feedback port; The second end of the fourth orifice is connected with the external oil tank. 12. The load-sensitive electrohydrostatic actuator according to claim 11, wherein the pressure-following servo valve further comprises a power device; The power device is used to apply an axial force along the axial direction of the valve core to the third column, and adjust the output hydraulic pressure of the outlet based on the axial force. 13. The load sensitive electrohydrostatic actuator according to claim 12, characterized in that: The power device is a proportional electromagnet or a voice coil motor. 14. The load-sensitive electrohydrostatic actuator according to claim 13, wherein the pressure-following servo valve further comprises: a second spring disposed in the third rod chamber and a third spring disposed in the third rodless chamber; The elastic directions of the second spring and the third spring coincide with the axis of the valve core, and the second spring and the third spring work in a non-stretched state.