EHA with quick start function and voltage stabilization control method

Abstract

The invention discloses an EHA with a quick start function and a voltage stabilization control method, and the EHA comprises a controller, a driver, a quick start module, and a power supply and adjustment module. The quick starting module comprises an energy accumulator and a high-speed switch valve set and is used for being quickly opened or closed when receiving a PWM signal from the controller so as to control release and supplement of high-pressure oil in the energy accumulator, and therefore a piston rod of the hydraulic cylinder is controlled to quickly stretch out. The novel electro-hydrostatic actuator of a loop of an energy accumulator and a high-speed switch valve group is additionally arranged on a piston side pipeline of a hydraulic cylinder, when the electro-hydrostatic actuator is started, high-pressure oil in the energy accumulator can be rapidly released to the hydraulic cylinder, a piston rod of the hydraulic cylinder is made to rapidly stretch out to a to-be-operated position, and rapid starting of the electro-hydrostatic actuator is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of hydraulic transmission, and in particular to an EHA with a quick start function and a voltage stabilization control method. Background Art

[0002] Electro-Hydrostatic Actuator (EHA) is a new type of servo actuator. It is a closed hydraulic system that integrates motors, hydraulic pumps, valves and actuators (hydraulic cylinders or hydraulic motors). It is more efficient, reliable and convenient than traditional centralized oil supply hydraulic systems. It reduces the layout of hydraulic pipelines, thereby reducing the weight of the entire system, making it easy to replace and maintain, which is conducive to the miniaturization and intelligence of modern equipment. It is widely used in aircraft, rockets, ships, robots and other fields.

[0003] When the EHA is installed vertically, it should be able to withstand the vertical downward load and land quickly. Although the hydraulic leveling system based on the EHA responds faster than the traditional centralized oil supply hydraulic system, the piston rod extension time is still relatively long because the motor speed cannot change suddenly. After the motor is started, the motor speed gradually reaches the maximum value, and the system flow increases with the motor speed. There is no flow output before crossing the system flow dead zone. Therefore, it is difficult to meet the rapidity requirements in specific applications by relying solely on control strategies. Summary of the invention

[0004] The embodiment of the present application can achieve the purpose of rapid startup by providing an EHA with a rapid startup function and a voltage stabilization control method. At the same time, by proposing a voltage stabilization control method applied to an electrostatic hydraulic actuator, the stability of the operation of the electrostatic hydraulic actuator can be improved.

[0005] In order to achieve the above object, the technical solution of the embodiment of the present invention is:

[0006] In the first aspect, an embodiment of the present invention provides an EHA with a quick start function, comprising: a controller, a driver, a quick start module, and a power supply and regulation module; the controller is used to receive and execute command signals from a host computer to control the operation of the entire electrostatic hydraulic actuator; the driver is electrically connected to the controller, and is used to drive the servo motor in the power supply and regulation module to rotate when receiving a drive command from the controller; the quick start module includes an accumulator and a high-speed switching valve group; the accumulator is connected to the pipeline on one side of the rodless chamber of the hydraulic cylinder, and the high-speed switching valve group is arranged between the accumulator and the hydraulic cylinder, and is used to switch the servo motor on the rodless chamber of the hydraulic cylinder when the accumulator is connected. It opens or closes quickly when receiving a PWM signal from the controller to control the release and replenishment of the high-pressure oil in the accumulator, thereby controlling the rapid extension of the piston rod of the hydraulic cylinder; a power supply and adjustment module includes a servo motor, a bidirectional gear pump, an oil tank and a bidirectional hydraulic lock; the servo motor is driven by a driver to drive the bidirectional gear pump to work, so that the pressure oil in the oil tank flows to the rodless chamber of the hydraulic cylinder, pushing the hydraulic cylinder body to move; one port of the bidirectional gear pump is connected to the rodless chamber of the hydraulic cylinder, and the other port is connected to the rod chamber of the hydraulic cylinder; the bidirectional hydraulic lock is used to keep the oil circuit locked when the piston rod is extended or retracted.

[0007] In some possible implementations, the high-speed switching valve group includes multiple high-speed switching valves for controlling the flow direction of high-pressure oil in the accumulator; including when receiving an open PWM signal from the controller, instantly releasing the high-pressure oil in the accumulator to the rodless chamber of the hydraulic cylinder, causing a pressure difference on both sides of the hydraulic cylinder piston, and the piston rod of the hydraulic cylinder is quickly extended to the working position under the action of the high-pressure oil; and when the piston rod is retracted, the oil flowing out of the rodless chamber of the hydraulic cylinder is replenished to the accumulator.

[0008] In some possible implementations, the electrostatic hydraulic actuator further includes a proportional solenoid valve disposed between the high-speed switching valve group and the rod-side circuit of the hydraulic cylinder, for controlling the speed of the inflow or outflow of the high-pressure oil in the accumulator.

[0009] In some possible implementations, a displacement sensor is provided on the hydraulic cylinder piston rod to monitor the position of the hydraulic cylinder piston rod in real time and feed back the position information to the controller.

[0010] In some possible implementations, the electrostatic hydraulic actuator further includes a pressure feedback module, including a plurality of pressure sensors, for monitoring the pressure of two chambers of the hydraulic cylinder in real time and feeding back the pressure information to the controller.

[0011] In some possible implementations, the controller is also used to adjust the opening of the high-speed switching valve group through a preset pressure stabilization control method according to the pressure information provided by the pressure feedback module to stabilize the pressure at the accumulator outlet, thereby maintaining the pressure in the two chambers of the hydraulic cylinder stable.

[0012] In the second aspect, an embodiment of the present invention provides a pressure stabilization control method for the EHA with a quick start function of the first aspect, comprising: dynamically adjusting the control signal applied to the proportional solenoid valve according to the natural frequency and the optimal absorption frequency of the accumulator-hydraulic cylinder circuit to achieve optimal absorption of pressure pulsations.

[0013] In some possible implementations, the output signal of the voltage regulation control algorithm is expressed as:

[0014]

[0015] Among them, f(u v ) is the output signal of the voltage regulation control algorithm, u v is the control signal applied to each high-speed switch valve, t is the system operation time, t0 is the time when the piston rod displacement reaches the specified position, t1 is the external load force disturbance moment, t2 is the time when it is expected to reach the specified position again, λ1 is the adaptive coefficient before the disturbance occurs, λ2 is the adaptive coefficient after the disturbance occurs, K a is the adaptive coefficient.

[0016] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0017] In the embodiment of the present invention, a new configuration EHA system is added with an "accumulator + high-speed switching valve group" circuit on the hydraulic cylinder piston side pipeline. When the EHA is started, the high-pressure oil in the accumulator can be quickly released to the hydraulic cylinder, so that the piston rod of the hydraulic cylinder is quickly extended to the working position, thereby realizing the rapid start-up of the EHA. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the embodiments of the present invention will be briefly introduced below. The accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of the structure of an EHA with a quick start function provided for the implementation of the present invention;

[0020] Figure 2 This is a structural schematic diagram of a high-speed switch valve group in an embodiment of the present invention;

[0021] Figure 3 It is a structural schematic diagram of another EHA with a quick start function in an embodiment of the present invention;

[0022] Figure 4 This is a startup simulation effect diagram of an EHA with a quick startup function according to an embodiment of the present invention;

[0023] Figure 5 A block diagram of a voltage stabilization control method provided by an embodiment of the present invention.

[0024] Icons: 11. Controller; 12. Driver; 13. Quick start module; 14. Power supply and regulation module; 131. Accumulator; 132. High-speed switching valve group; 15. Hydraulic cylinder; 151. Rodless chamber; 152. Piston rod; 153. Rod chamber; 141. Servo motor; 142. Bidirectional gear pump; 143. Oil tank; 144. Bidirectional hydraulic lock; 1521. Displacement sensor; 16. Check valve; 17. Overflow valve. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] In the relevant description of this embodiment, the terms "including, containing, having" and the like are open terms and are generally understood to include but not be limited to; the term "at least one" is generally understood to mean one or more, where "plurality" refers to two or more; the term "at least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items, for example, "at least one of a, b or c", or "at least one of a, b and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively; the symbol "A / B" is used to describe the selection relationship of associated objects, generally indicating an "or" relationship before and after.

[0027] In the following description of the present embodiment, the terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0028] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0029] Those skilled in the art will appreciate that the numerical ranges in the embodiments of the present application are to be construed as also specifically disclosing each intermediate value between the upper and lower limits of the scope. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded in the scope.

[0030] Unless otherwise stated, the technical / scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs. Although this application only describes preferred methods and compositions, any methods and compositions similar or equivalent to these may also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe methods and / or compositions related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0031] In order to illustrate the technical solution of the present invention, specific embodiments are provided below for illustration.

[0032] Electro-Hydrostatic Actuator (EHA) is a new type of servo actuator. It is a closed hydraulic system that integrates motors, hydraulic pumps, valves and actuators (hydraulic cylinders or hydraulic motors). It is more efficient, reliable and convenient than traditional centralized oil supply hydraulic systems. It reduces the layout of hydraulic pipelines, thereby reducing the weight of the entire system, making it easy to replace and maintain, which is conducive to the miniaturization and intelligence of modern equipment. It is widely used in aircraft, rockets, ships, robots and other fields.

[0033] When the EHA is installed vertically, it should be able to withstand the vertical downward load and land quickly. Although the hydraulic leveling system based on the EHA responds faster than the traditional centralized oil supply hydraulic system, the piston rod extension time is still relatively long because the motor speed cannot change suddenly. After the motor is started, the motor speed gradually reaches the maximum value, and the system flow increases with the motor speed. There is no flow output before crossing the system flow dead zone. Therefore, it is difficult to meet the rapidity requirements in specific applications by relying solely on control strategies.

[0034] Based on this, the embodiment of the present invention provides an EHA with a quick start function, which adds a new configuration of an EHA with an "accumulator + high-speed switch valve group" circuit on the hydraulic cylinder piston side pipeline to achieve the purpose of quick start. At the same time, in order for the accumulator to absorb pressure and flow pulsations at the optimal frequency when the load outside the system is disturbed, a voltage stabilization control method applied to an electrostatic hydraulic actuator is proposed to improve the stability of the operation of the electrostatic hydraulic actuator.

[0035] Figure 1 A schematic diagram of the structure of an EHA with a quick start function provided for the implementation of the present invention, see Figure 1 As shown, the EHA with the quick start function may include:

[0036] Controller 11, driver 12, quick start module 13 and power supply and regulation module 14;

[0037] The controller 11 is used to receive and execute the command signal from the host computer to control the operation of the entire electrostatic hydraulic actuator;

[0038] The driver 12 is electrically connected to the controller 11 and is used to drive the servo motor 141 in the power supply and regulation module 14 to rotate when receiving a driving instruction from the controller 11;

[0039] The quick start module 13 includes an accumulator 131 and a high-speed switch valve group 132; the accumulator 131 is connected to the pipeline on one side of the rodless chamber 151 of the hydraulic cylinder 15, and the high-speed switch valve group 132 is arranged between the accumulator 131 and the hydraulic cylinder 15, and is used to quickly open or close when receiving a pulse width modulation (PWM) signal from the controller 11, so as to control the release and replenishment of the high-pressure oil in the accumulator 131, thereby controlling the rapid extension of the piston rod 152 of the hydraulic cylinder 15;

[0040] The power supply and regulation module 14 includes a servo motor 141, a bidirectional gear pump 142, an oil tank 143 and a bidirectional hydraulic lock 144; the servo motor 141 is driven by the driver 12 to drive the bidirectional gear pump 142 to work, so that the pressure oil in the oil tank 143 flows to the rodless chamber 151 of the hydraulic cylinder 15, pushing the cylinder body of the hydraulic cylinder 15 to move; one port of the bidirectional gear pump 142 is connected to the rodless chamber 151 of the hydraulic cylinder 15, and the other port is connected to the rod chamber 153 of the hydraulic cylinder 15; the bidirectional hydraulic lock 144 is used to keep the oil circuit locked when the piston rod 152 is extended or retracted.

[0041] Specifically, when the controller 11 receives the command signal for the piston rod 152 of the hydraulic cylinder 15 to extend from the upper computer, the driver 12 is powered. The servo motor 141 drives the bidirectional gear pump 142 to work, and the outlet pressure of the bidirectional gear pump 142 gradually increases. At the same time, the high-speed switch valve group 132 in the quick start module 13 receives the start PWM signal sent by the controller 11, so that the high-pressure oil in the accumulator 131 is quickly released and flows into the rodless chamber 151 of the hydraulic cylinder 15. A pressure difference is generated between the rod chamber 153 and the rodless chamber 151 of the hydraulic cylinder 15, so that the piston rod 152 is quickly extended to the waiting working position under the action of the high-pressure oil. At this time, the high-speed switch valve group 132 disconnects the communication between the accumulator 131 and the hydraulic cylinder 15, and the bidirectional gear pump 142 continues to work. The outlet pressure oil of the bidirectional gear pump 142 flows to the rodless chamber 151 of the hydraulic cylinder 15 through the bidirectional hydraulic lock 144, and continuously pushes the cylinder body of the hydraulic cylinder 15 to move until it stops after completing a specific working condition.

[0042] In some embodiments, the high-speed switch valve group 132 includes at least two high-speed switch valves for controlling the flow direction of the high-pressure oil in the accumulator 131;

[0043] Specifically, the high-pressure oil flow direction in the accumulator 131 is controlled by the high-speed switching valve, including: when receiving the opening PWM signal sent by the controller 11, the high-pressure oil in the accumulator 131 is instantly released to the rodless chamber 151 of the hydraulic cylinder 15, so that a pressure difference is generated on both sides of the piston of the hydraulic cylinder 15, and the piston rod 152 of the hydraulic cylinder 15 is rapidly extended to the working position under the action of the high-pressure oil; and when the piston rod 152 is retracted, the oil flowing out of the rodless chamber 151 of the hydraulic cylinder 15 is replenished to the accumulator 131.

[0044] For example, Figure 2 FIG. 1 is a schematic diagram of the structure of a high-speed switch valve group 132 in an embodiment of the present invention. Taking the high-speed switch valve group 132 including four high-speed switch valves as an example, see Figure 2 As shown, the high-speed switch valve group 132 includes: a first high-speed switch valve 1, a second high-speed switch valve 2, a third high-speed switch valve 3 and a fourth high-speed switch valve 4;

[0045] Specifically, when the controller 11 sends out the first and second PWM signals of opening, the first high-speed switch valve 1 receives the first PWM signal, and the second high-speed switch valve 2 receives the second PWM signal; at this time, the first high-speed switch valve 1 and the second high-speed switch valve 2 remain in the open state, and the third high-speed switch valve 3 and the fourth high-speed switch valve 4 remain in the closed state. The high-pressure oil in the accumulator 131 is instantly released to the rodless chamber 151 of the hydraulic cylinder 15 through the first high-speed switch valve 1 and the second high-speed switch valve 2, so that a pressure difference is generated on both sides of the piston of the hydraulic cylinder 15, and the piston rod 152 of the hydraulic cylinder 15 is quickly extended to the waiting position under the action of the high-pressure oil;

[0046] When the controller 11 sends out the third and fourth PWM signals to close, the third high-speed switch valve 3 receives the third PWM signal, and the fourth high-speed switch valve 4 receives the fourth PWM signal; at this time, the third high-speed switch valve 3 and the fourth high-speed switch valve 4 remain in the open state, and the first high-speed switch valve 1 and the second high-speed switch valve 2 remain in the closed state, and the oil flowing out of the rodless chamber 151 of the hydraulic cylinder 15 is replenished to the accumulator 131 through the third high-speed switch valve 3 and the fourth high-speed switch valve 4.

[0047] In some embodiments, the electrostatic hydraulic actuator further includes a proportional solenoid valve disposed between the high-speed switch valve group 132 and the hydraulic cylinder 15 circuit, a pressure feedback module, and a displacement sensor disposed on the piston rod 152 of the hydraulic cylinder 15. The proportional solenoid valve includes at least two, which are used to control the speed of the inflow or outflow of the high-pressure oil in the accumulator 131; the displacement sensor is used to monitor the position of the piston rod 152 of the hydraulic cylinder 15 in real time, and feed back the position information to the controller 11; the pressure feedback module includes a plurality of pressure sensors, which are used to monitor the pressure of the two chambers of the hydraulic cylinder 15 in real time, and feed back the pressure information to the controller 11.

[0048] For example, Figure 3 FIG. 1 is a schematic diagram of the structure of another EHA with a quick startup function in an embodiment of the present invention. Figure 3 As shown, the high-speed switch valve group 132 includes a first high-speed switch valve 1, a second high-speed switch valve 2, a third high-speed switch valve 3 and a fourth high-speed switch valve 4. A displacement sensor 1521 is arranged on the piston rod 152. There are two proportional solenoid valves, including a proportional solenoid valve 1 and a proportional solenoid valve 2. One end of the proportional solenoid valve 1 is connected to the port 1 of the bidirectional gear pump 142, and the other end is connected between the third high-speed switch valve 3 and the fourth high-speed switch valve 4; one end of the proportional solenoid valve 2 is connected to the port 1 of the bidirectional gear pump 142, and the other end is connected between the second high-speed switch valve 2 and the third high-speed switch valve 3. The pressure feedback module includes a pressure sensor 1 arranged on the side of the rodless chamber 151 of the hydraulic cylinder 15 and a pressure sensor 2 arranged on the side of the rod chamber 153. At the same time, a pressure sensor 3 is also arranged on the accumulator 131 for monitoring the outlet pressure of the accumulator 131 and feeding back to the controller 11 in real time. In addition, the above-mentioned electrostatic hydraulic actuator is also provided with two one-way valves 16 and two overflow valves 17. The specific connection method can be referred to. Figure 3 shown.

[0049] The following Figure 3 Taking the electrostatic hydraulic actuator shown in the figure as an example, the working principle of the electrostatic hydraulic actuator with a quick start function in the embodiment of the present invention is described:

[0050] When the controller 11 receives the control command signal for the extension of the piston rod 152 of the hydraulic cylinder 15 sent by the upper computer, the driver 12 is powered. At this time, the servo motor 141 drives the bidirectional gear pump 142 to work, and the outlet pressure of the bidirectional gear pump 142 gradually increases; the first high-speed switch valve 1 receives the first PWM signal, and the second high-speed switch valve 2 receives the second PWM signal; at this time, the first high-speed switch valve 1 and the second high-speed switch valve 2 remain in the open state, and the third high-speed switch valve 3 and the fourth high-speed switch valve 4 do not receive the PWM signal and remain in the closed state; the high-pressure oil in the accumulator 131 is instantly released to the rodless chamber 151 of the hydraulic cylinder 15 through the first high-speed switch valve 1 and the second high-speed switch valve 2, so that a pressure difference is generated on both sides of the piston of the hydraulic cylinder 15, and the piston rod 152 of the hydraulic cylinder 15 is quickly extended to the waiting position under the action of the high-pressure oil.

[0051] After the piston rod 152 is extended to the working position, the first high-speed switch valve 1 and the second high-speed switch valve 2 are disconnected. The bidirectional gear pump 142 continues to work, and the pressure oil at the outlet of the bidirectional gear pump 142 flows to the rodless chamber 151 of the hydraulic cylinder 15 through the bidirectional hydraulic lock 144, continuously pushing the cylinder body of the hydraulic cylinder 15 to move until it stops after completing a specific working condition. The displacement sensor 1521 set on the piston rod 152 transmits the position information of the piston rod 152 to the controller 11, and the bidirectional hydraulic lock 144 locks the piston rod 152 in the current position. When the system pressure of the electrostatic hydraulic actuator does not exceed the preset given value of the overflow valve 17, the two overflow valves 17 are not opened. At the same time, the pressure sensor 1 and the pressure sensor 2 feed back the pressure values ​​of the two chambers of the hydraulic cylinder 15 to the controller 11 in real time.

[0052] In some embodiments, the process of replenishing the accumulator 131 includes two situations. Figure 3 The structure of the electrostatic hydraulic actuator shown in the figure is used as an example to illustrate:

[0053] In the first aspect, when the controller 11 receives the instruction to retract the piston rod 152 of the hydraulic cylinder 15, the controller 11 causes the driver 12 to output a negative voltage signal to the servo motor 141. The servo motor 141 reverses, the high and low pressure ports between port 1 and port 2 of the bidirectional gear pump 142 are exchanged, and the pressure oil of port 2 of the bidirectional gear pump 142 flows to the rod chamber 153 of the hydraulic cylinder 15 through the bidirectional hydraulic lock 144, pushing the piston rod 152 to retract; at the same time, the third high-speed switch valve 3 receives the third PWM signal, and the fourth high-speed switch valve 4 receives the fourth PWM signal, and opens the corresponding opening according to the given duty cycle; the first high-speed switch valve 1 and the second high-speed switch valve 2 do not receive the PWM signal and are in a closed state; the proportional solenoid valve 2 is not energized and is in a closed state. The oil flowing out of the rodless chamber 151 of the hydraulic cylinder 15 is replenished to the accumulator 131 through the third high-speed switch valve 3 and the fourth high-speed switch valve 4 of the high-speed switch valve group 132. The pressure sensor 3 feeds back the outlet pressure of the accumulator 131 to the controller 11 in real time until the outlet pressure of the accumulator 131 reaches a preset value, the proportional solenoid valve 2 is energized and opened, and the oil in the rodless chamber 151 of the hydraulic cylinder 15 flows through the proportional solenoid valve 2 and the two-way hydraulic lock 144 to the oil suction port (port 1) of the two-way gear pump 142 and enters the oil tank 143.

[0054] Secondly, in the initial state, when the outlet pressure of the accumulator 131 is lower than the preset expected value, the controller 11 gives a positive voltage signal to the driver 12, and at the same time gives a positive signal to the proportional solenoid valve 1 to open it, and gives a PWM signal to the fourth high-speed switch valve 4, and the proportional solenoid valve 2 is powered off; the servo motor 141 rotates forward, driving the port 1 of the bidirectional gear pump 142 to output pressure oil, and the pressure oil is replenished to the accumulator 131 through the proportional solenoid valve 1 and the fourth high-speed switch valve 4.

[0055] It should be noted that the high-pressure oil in the accumulator 131 and the pressure oil stored in the oil tank 143 are the same oil.

[0056] In the embodiment of the present invention, a new configuration EHA system is formed by adding an accumulator 131 + high-speed switching valve group 132 circuit to the pipeline on the side of the rodless chamber 151 of the hydraulic cylinder 15. When the EHA is started, the high-pressure oil in the accumulator 131 can be quickly released to the hydraulic cylinder 15, so that the piston rod 152 of the hydraulic cylinder 15 can be quickly extended to the working position, thereby realizing the rapid start of the EHA.

[0057] For example, Figure 4 1 is a start-up simulation effect diagram of an EHA with a quick start function according to an embodiment of the present invention. The horizontal axis is time (time), the unit is seconds (s), and the vertical axis is the extended length of the piston rod 152, the unit is meters (m). Figure 4 As shown, the starting speed of the electrostatic hydraulic actuator can be greatly improved by using the electrostatic hydraulic actuator with a quick starting function.

[0058] Understandably, as above Figure 3 In the electrostatic hydraulic actuator shown, the accumulator 131 and the bidirectional gear pump 142 are two independent control loops. An automatic controller, such as a PID controller (Proportion Integration Differentiation), is used in the main loop controlled by the bidirectional gear pump 142. During the no-load startup phase of the EHA, the accumulator 131 is the main power source. When the piston rod 152 retracts, the third high-speed switch valve 3 and the fourth high-speed switch valve 4 of the high-speed switch valve group 132 receive a PWM signal, the first high-speed switch valve 1 and the second high-speed switch valve 2 have no input signal, and the accumulator 131 is filled with liquid. Therefore, the selection of the accumulator 131 is crucial to ensure the stable startup of the system. When the volume of the accumulator 131 is large, the volume will increase accordingly. When the outlet pressure of the accumulator 131 is extremely high, the pressure pulsation in the startup phase of the EHA intensifies. In practical applications, the volume and outlet pressure of the accumulator 131 should not be too large (not conducive to integration and smooth operation). In the startup phase, the accumulator 131 acts as an auxiliary power source. After the piston rod 152 is extended to a given working position under no-load, the piston rod 152 continues to push the external load to move under the drive of the bidirectional gear pump 142. When the external load force is disturbed, pressure and flow pulsations can be observed in both chambers of the hydraulic cylinder 152 (the rodless chamber 151 and the rod chamber 153), and the amplitude of such pulsations is often larger under high load conditions. Therefore, in some embodiments, the present invention also provides a voltage stabilization control method applied to the above-mentioned electrostatic hydraulic actuator, including: dynamically adjusting the control signal applied to the proportional solenoid valve 1 and the proportional solenoid valve 2 according to the natural frequency and the optimal absorption frequency of the circuit from the accumulator 131 to the hydraulic cylinder 15 to achieve optimal absorption of pressure pulsations.

[0059] Specifically, Figure 5 This is a block diagram of a voltage stabilization control method provided by an embodiment of the present invention. Figure 5 As shown, PWM1 to PWM4 are respectively the first PWM signal, the second PWM signal, the third PWM signal and the fourth PWM signal as described above, x is the multiplication sign, u is v is the control signal applied to the proportional solenoid valve, in which a parameter adaptive controller is provided. K u is the proportionality constant, x v is the displacement of the proportional valve spool, K a is the adaptive coefficient. Figure 5 Where Sig(t) is a piecewise function of time. It can be expressed by the following formula (1):

[0060]

[0061] Among them, t0 is the time when the piston rod displacement reaches the specified position, t1 is the external load force disturbance moment, and t2 is the time when it is expected to reach the specified position again. The piston rod is expected to reach the specified position again after t2, λ1 is the adaptive coefficient before the disturbance occurs, and λ2 is the adaptive coefficient after the disturbance occurs.

[0062] The output signal f(u v ) can be expressed by the following formula (2):

[0063] f(u v )=u v ·Sig(t) (2)

[0064] The optimal frequency of the accumulator-to-cylinder circuit to absorb pressure pulsation can be expressed by the following formula (3):

[0065]

[0066] Among them, ω a is the optimal frequency for absorbing pressure pulsation in the circuit from accumulator to hydraulic cylinder, p s0 is the steady-state pressure value of the circuit from the accumulator to the hydraulic cylinder, K is the insulation coefficient of the accumulator, S a is the accumulator inlet flow area, l is the length of the accumulator inlet pipe, V a is the oil volume of the accumulator, and ρ is the oil density.

[0067] When the pressure of the accumulator-hydraulic cylinder circuit fluctuates, assuming that the pulsating pressure is p, the absorption pulsation frequency of the accumulator is ω a1 It can be expressed by the following formula (4):

[0068]

[0069] Assume that the flow area of ​​the accumulator inlet pipe is S a1 When the accumulator works at the optimal absorption frequency, S a1 =K a S a , when the above formula (3) and formula (4) are equal, K a =p s0 / p, t0≤t≤t2.

[0070] Based on this, the above formula (2) can be further expressed by the following formula (5):

[0071]

[0072] In the above embodiment, the values ​​of λ1 and λ2 may be selected by manual trial and error, or may be optimized by any other existing optimization algorithm, which is not specifically limited in the embodiment of the present invention.

[0073] In the embodiment of the present invention, a new configuration EHA of "accumulator + high-speed switch valve group" circuit is added to the pipeline on the piston side of the hydraulic cylinder to achieve the purpose of rapid startup. At the same time, in order for the accumulator to absorb pressure and flow pulsation at the optimal frequency when the load outside the system is disturbed, a voltage stabilization control method applied to the electrostatic hydraulic actuator is proposed to improve the stability of the operation of the electrostatic hydraulic actuator.

[0074] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0075] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. An EHA with a quick start function, characterized in that: include: Controllers, drivers, quick start modules, and power supply and regulation modules; The controller is used to receive and execute command signals from the host computer to control the operation of the entire electrostatic hydraulic actuator; The driver is electrically connected to the controller and is used to drive the servo motor in the power supply and regulation module to rotate when receiving a driving instruction from the controller; The quick start module includes an accumulator and a high-speed switch valve group; the accumulator is connected to the pipeline on one side of the rodless chamber of the hydraulic cylinder, and the high-speed switch valve group is arranged between the accumulator and the hydraulic cylinder, and is used to quickly open or close when receiving a PWM signal from the controller to control the release and replenishment of the high-pressure oil in the accumulator, thereby controlling the rapid extension of the piston rod of the hydraulic cylinder; The power supply and regulation module includes a servo motor, a bidirectional gear pump, an oil tank and a bidirectional hydraulic lock; the servo motor is driven by the driver to drive the bidirectional gear pump to work, so that the pressure oil in the oil tank flows to the rodless chamber of the hydraulic cylinder, pushing the hydraulic cylinder body to move; one port of the bidirectional gear pump is connected to the rodless chamber of the hydraulic cylinder, and the other port is connected to the rod chamber of the hydraulic cylinder; the bidirectional hydraulic lock is used to maintain the locking state of the oil circuit when the piston rod is extended or retracted.

2. The electrostatic hydraulic actuator according to claim 1, characterized in that: The high-speed switch valve group includes at least two high-speed switch valves, which are used to control the flow direction of the high-pressure oil in the accumulator; including when receiving the opening PWM signal sent by the controller, the high-pressure oil in the accumulator is instantly released to the rodless chamber of the hydraulic cylinder, so that a pressure difference is generated on both sides of the hydraulic cylinder piston, and the piston rod of the hydraulic cylinder is quickly extended to the working position under the action of the high-pressure oil; and when the piston rod is retracted, the oil flowing out of the rodless chamber of the hydraulic cylinder is replenished to the accumulator.

3. The electrostatic hydraulic actuator according to claim 2, characterized in that: The electrostatic hydraulic actuator further comprises a proportional solenoid valve disposed between the high-speed switch valve group and the hydraulic cylinder circuit, for controlling the speed of the inflow or outflow of the high-pressure oil in the accumulator.

4. The electrostatic hydraulic actuator according to claim 3, characterized in that: The hydraulic cylinder piston rod is provided with a displacement sensor for real-time monitoring of the position of the hydraulic cylinder piston rod and feeding back the position information to the controller.

5. The electrostatic hydraulic actuator according to claim 4, characterized in that: The electrostatic hydraulic actuator further comprises a pressure feedback module, comprising a plurality of pressure sensors, for real-time monitoring of the pressure of the two chambers of the hydraulic cylinder and feeding back the pressure information to the controller.

6. The electrostatic hydraulic actuator according to claim 5, characterized in that: The controller is also used to adjust the opening of the high-speed switch valve group through a preset pressure stabilization control method according to the pressure information provided by the pressure feedback module to stabilize the pressure at the accumulator outlet, thereby maintaining the pressure of the two chambers of the hydraulic cylinder stable.

7. A voltage stabilization control method for an EHA with a quick start function as claimed in any one of claims 1 to 6, characterized in that: include: The control signal applied to the high-speed switching valve is dynamically adjusted based on the natural frequency and the best absorption frequency of the accumulator-to-cylinder circuit to achieve optimal absorption of pressure pulsations.

8. The method according to claim 7, characterized in that The output signal of the voltage stabilization control method is expressed as: Among them, f(u v ) is the output signal of the voltage stabilization control method, u v is the control signal applied to the proportional solenoid valve, t is the system operation time, t0 is the time when the piston rod displacement reaches the specified position, t1 is the external load force disturbance moment, t2 is the time when it is expected to reach the specified position again, λ1 is the adaptive coefficient before the disturbance occurs, λ2 is the adaptive coefficient after the disturbance occurs, K a is the adaptive coefficient.

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