A single-acting electro-hydraulic actuator

Abstract

The present invention discloses a single-acting electro-hydraulic actuator, belonging to the field of actuators, comprising: a hydraulic cylinder, a hydraulic cylinder cover sealed and connected to a first end of the hydraulic cylinder, a disc spring cylinder connected to a second end of the hydraulic cylinder, a rack piston rod axially movable within the hydraulic cylinder, a gear shaft rotatably disposed on the hydraulic cylinder and meshing with a rack portion on the rack piston rod, a disc spring disposed within the disc spring cylinder, a reset push rod disposed within the disc spring cylinder and having a first end extending into the hydraulic cylinder, a first oil port and a second oil port provided on the hydraulic cylinder, and a hydraulic power mechanism connected between the first oil port and the second oil port. The single-acting electro-hydraulic actuator provided by the present invention has a power-off self-closing function. When the electro-hydraulic actuator is powered off, the elastic force of the disc spring can drive the valve to automatically close, thereby ensuring the power-off safety of the valve.

Description

Technical Field

[0001] The present invention relates to the field of electro-hydraulic actuators, in particular to a single-acting electro-hydraulic actuator. Background Art

[0002] Electro-hydraulic actuators are devices that convert electrical energy into hydraulic energy and use this energy to achieve mechanical motion. They feature large stroke, high thrust or torque, fast response time, high sensitivity, and compact design. They are widely used for valve control in oil and gas pipelines, chemical processing, refining, oil depots, and docks, conveniently controlling valve opening and closing, as well as valve opening size. For example, patent CN117404513A discloses a multifunctional safety linkage valve electro-hydraulic actuator and its control method.

[0003] An electro-hydraulic actuator typically consists of a motor, pump, hydraulic cylinder, control valve, and oil tank. Its basic operating principle is as follows: the motor drives the pump, which draws hydraulic oil from the tank and delivers it to the hydraulic cylinder through a pipeline. The hydraulic oil's pressure then propels the controlled object to perform a desired action, such as opening or closing a valve. During this process, the valve's opening and closing angle is typically controlled by controlling the flow of hydraulic oil.

[0004] Patents such as CN105422955B, "An Electro-Hydraulic Actuator for a Needle Valve," CN103511004B, "A Closed Electro-Hydraulic Actuator and Combination," and CN111706569B, "An Electro-Hydraulic Actuator and Control Method," disclose some conventional electro-hydraulic actuators. These conventional electro-hydraulic actuators typically require a separate oil tank, which increases the size of the actuator and hinders miniaturization. Furthermore, valve actuators are typically required to self-close upon power failure, a feature currently lacking in some current models.

[0005] Furthermore, for electro-hydraulic actuators that control the valve opening angle through the flow of hydraulic oil, factors such as the expansion and contraction characteristics of the hydraulic oil can affect flow control, compromising valve opening control accuracy. Changes in parameters such as the hydraulic oil's temperature and pressure can also affect its expansion and contraction characteristics. Furthermore, the common "creeping" phenomenon in motors (where the motor maintains a certain speed under zero voltage conditions, meaning that after the motor stops rotating, it continues to rotate for a certain period before finally stopping) can cause the oil pump to continue operating for a short period after the control motor stops. This can lead to an error between the hydraulic oil flow rate and the preset flow rate, which can also affect valve opening control accuracy. These errors are often non-negligible for applications requiring high valve control precision. However, a reliable solution to this problem is currently lacking. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a single-acting electro-hydraulic actuator in view of the deficiencies in the above-mentioned prior art.

[0007] To solve the above technical problems, the present invention adopts a technical solution: a single-acting electro-hydraulic actuator, which is used to drive a valve to perform an opening and closing action, and the single-acting electro-hydraulic actuator includes: a hydraulic cylinder, a hydraulic cylinder head sealed and connected to a first end of the hydraulic cylinder, a disc spring cylinder connected to a second end of the hydraulic cylinder, a rack piston rod movably arranged in the hydraulic cylinder along the axial direction, a gear shaft rotatably arranged on the hydraulic cylinder and meshing with a rack portion on the rack piston rod, a disc spring arranged in the disc spring cylinder, a reset push rod arranged in the disc spring cylinder and having a first end extending into the hydraulic cylinder, a first oil port and a second oil port provided in the hydraulic cylinder, and an oil power mechanism connected between the first oil port and the second oil port;

[0008] The first end and the second end of the rack piston rod are respectively provided with a front piston portion and a rear piston portion, the cavity between the front piston portion and the hydraulic cylinder cover and the inner wall of the hydraulic cylinder forms a first hydraulic oil chamber, and the cavity between the rear piston portion and the inner wall of the hydraulic cylinder forms a second hydraulic oil chamber; the first oil port is connected to the first hydraulic oil chamber, and the second oil port is connected to the second hydraulic oil chamber;

[0009] The disc spring is arranged in cooperation with the reset push rod, so that under the elastic force of the disc spring, the first end of the reset push rod has a pressing effect on the rear piston portion toward the side of the hydraulic cylinder cover;

[0010] The oil power mechanism realizes the function of conveying hydraulic oil between the first hydraulic oil chamber and the second hydraulic oil chamber through the first oil port and the second oil port. When the hydraulic oil is input from the second hydraulic oil chamber into the first hydraulic oil chamber, the pressure of the hydraulic oil causes the rack piston rod to move linearly toward the side of the disc spring cylinder, thereby driving the gear shaft to rotate counterclockwise, and finally driving the valve to open the valve; when the hydraulic oil is input from the first hydraulic oil chamber into the second hydraulic oil chamber, the elastic force of the disc spring causes the reset push rod to push the rack piston rod to move linearly toward the side of the hydraulic cylinder cover, thereby driving the gear shaft to rotate clockwise, and finally driving the valve to close the valve.

[0011] Preferably, a first oil delivery channel communicating with the first oil port, a first internal oil guide port communicating with the end of the first oil delivery channel, a second oil delivery channel communicating with the second oil port, and a second internal oil guide port communicating with the end of the second oil delivery channel are formed in the cylinder wall of the hydraulic cylinder. The first internal oil guide port is communicated with the first hydraulic oil chamber, and the communication position is located on the side of the hydraulic cylinder cover. The second internal oil guide port is communicated with the second hydraulic oil chamber.

[0012] Preferably, an adjusting screw is provided on the hydraulic cylinder head, and the end of the adjusting screw extends into the first hydraulic oil chamber to limit the extreme position of the linear motion of the rack piston rod toward the side of the hydraulic cylinder head by pressing the front piston part.

[0013] Preferably, a guide hole is formed in the middle of the connection position between the hydraulic cylinder and the disc spring cylinder;

[0014] The reset push rod includes a sleeve portion slidably arranged in the disc spring cylinder along the axial direction, a top column portion connected to the first end of the sleeve portion and extending into the hydraulic cylinder, and an annular convex portion connected between the sleeve portion and the top column portion, the annular convex portion contacts the movable end of the disc spring, and the top column portion is slidable through the guide hole;

[0015] A first oil storage hole is provided in the top column portion, a second oil storage hole communicating with the first oil storage chamber is provided in the sleeve portion, and an oil storage channel communicating with the first oil storage hole and the second hydraulic oil chamber is provided in the top column portion.

[0016] Preferably, the second end of the disc spring cylinder is sealed with a disc spring cylinder cover, and the disc spring cylinder cover is provided with an adjusting piston extending into the disc spring cylinder, and the adjusting piston includes a threaded rod threadedly connected to the disc spring cylinder cover, an adjusting shaft connected to the threaded rod, a limiting convex edge provided on the adjusting shaft, and a piston head connected to the end of the adjusting shaft and cooperatively inserted into the second oil storage hole;

[0017] A limiting hole with a diameter larger than that of the second oil storage hole is provided at the end of the sleeve portion, and a limiting step surface is formed between the limiting hole and the second oil storage hole; the limiting convex edge limits the limit position of the reset push rod moving toward the side of the disc spring cylinder cover by cooperating to press the limiting step surface.

[0018] Preferably, the oil power mechanism includes a first oil pipe connected to the first oil port, a first one-way valve provided on the first oil pipe, a flow meter provided on the first oil pipe and between the first oil port and the first one-way valve, an oil pump connected to an end of the first oil pipe, a motor connected to the oil pump, a second oil pipe connecting the oil pump to the second oil port, a third oil pipe connected between the first oil pipe and the second oil pipe, a first solenoid valve provided on the third oil pipe, a fourth oil pipe connected to the first oil pipe, a temperature sensor and a pressure sensor provided on the fourth oil pipe, and a controller connected to the motor;

[0019] The connection position of the third oil pipe and the first oil pipe is between the flow meter and the first one-way valve, and the connection position of the fourth oil pipe and the first oil pipe is between the flow meter and the first one-way valve;

[0020] The controller is in communication connection with the flow meter, the first solenoid valve, the temperature sensor, and the pressure sensor.

[0021] Preferably, a fifth oil pipe is connected between the third oil pipe and the first oil pipe, a second solenoid valve is provided on the fifth oil pipe, and the second solenoid valve is communicatively connected to the controller;

[0022] The connection position of the fifth oil pipe and the third oil pipe is between the first one-way valve and the first solenoid valve, and the connection position of the fifth oil pipe and the first oil pipe is between the first one-way valve and the oil pump;

[0023] The fourth oil pipe is provided with a second one-way valve, and the end of the fourth oil pipe is provided with an oil replenishing port;

[0024] The second oil pipe is connected to a sixth oil pipe, an exhaust valve is provided on the sixth oil pipe, and an exhaust port is provided at the end of the sixth oil pipe.

[0025] Preferably, the controller includes a control module and an oil flow correction module. The controller controls the motor according to the instruction, and then drives the oil pump through the motor to realize the valve opening and closing action. The control method of the controller includes:

[0026] S1, valve opening action:

[0027] S1-1, the controller obtains the valve opening angle θ according to the instruction, and calculates the flow rate Q of the hydraulic oil pumped into the first hydraulic oil chamber required for the valve opening angle θ Lθ ;

[0028] S1-2, the oil flow correction module adjusts the flow Q according to the detection results of the temperature sensor and the pressure sensor. Lθ Perform the initial correction to obtain the initial correction flow Q' Lθ ;

[0029] S1-3, the oil flow correction module then adjusts the oil flow rate according to the set speed r of the motor. e And the detection results of temperature sensor and pressure sensor are analyzed to calculate the motor creep flow increment △Q y ; Then correct the initial flow Q' Lθ Make correction again to get the final correction flow Q Sθ , Q Sθ =Q' Lθ -△Q y ;

[0030] S1-4, the controller controls the motor to rotate at a set speed r eWhen the flow meter detects that the flow rate of the hydraulic oil pumped into the first hydraulic oil chamber reaches Q Sθ When the motor stops working;

[0031] Among them, after the hydraulic oil enters the first hydraulic oil chamber through the first oil port, the pressure of the hydraulic oil causes the rack piston rod to move linearly toward the side of the disc spring cylinder, driving the gear shaft to rotate counterclockwise, thereby driving the valve to open the valve;

[0032] S2, valve closing action:

[0033] The control method for closing the valve is either of the following two methods:

[0034] S2-1, automatic reset valve closing:

[0035] When the valve is closed, the controller controls the oil pump to stop working and controls the first solenoid valve to open, so that the first oil port and the second oil port are connected;

[0036] Under the elastic force of the disc spring, the reset push rod moves linearly toward the side of the hydraulic cylinder cover and presses the rear piston part of the rack piston rod, so that the rack piston rod moves linearly toward the side of the hydraulic cylinder cover, driving the gear shaft to rotate clockwise until the front piston part of the rack piston contacts the adjusting screw and stops, thereby driving the valve to complete the valve closing action;

[0037] S2-2, auxiliary rapid reset valve closing:

[0038] When closing the valve, the controller controls the first solenoid valve to close and the second solenoid valve to open, and controls the motor to rotate at the set speed r e Reverse rotation works, pumping the hydraulic oil in the first hydraulic oil chamber into the second hydraulic oil chamber. When the flow meter detects that the flow rate of the hydraulic oil pumped out of the first hydraulic oil chamber reaches Q Sθ When the motor stops working;

[0039] Among them, the hydraulic oil enters the second hydraulic oil chamber from the first hydraulic oil chamber, and at the same time, under the elastic force of the disc spring, the rack piston rod moves linearly toward the side of the hydraulic cylinder head, driving the gear shaft to rotate clockwise, thereby driving the valve to complete the valve closing action.

[0040] Preferably, the oil flow correction module includes a data preprocessing submodule, an oil expansion and contraction flow error prediction submodule, a motor creep flow error prediction submodule and a calculation output submodule;

[0041] The oil expansion and contraction flow error prediction submodule and the motor creep flow error prediction submodule both use a method based on a machine learning algorithm to perform error prediction;

[0042] The oil expansion and contraction flow error prediction submodule is constructed by the following method:

[0043] 1-1) Construct the expansion and contraction error training dataset S1:

[0044] 1-1-1) For any valve opening angle ω, calculate the standard hydraulic oil flow rate Q required to be pumped into the first hydraulic oil chamber corresponding to the valve opening angle ω bω ; The temperature of the hydraulic oil in the standard state is T b , pressure is P b ;

[0045] 1-1-2) Corresponding to the valve opening angle ω, determine any temperature T through experiment i , pressure P i The actual flow rate Q of the hydraulic oil required to be pumped into the first hydraulic oil chamber ω (T i , P i ), calculate the temperature difference △T between the actual hydraulic oil and the standard hydraulic oil i , pressure difference △P i and flow difference △Q ω (T i , P i ):

[0046] △T i =T i -T b , △P i =P i -P b , △Q ω (T i , P i ) = Q bω -Q ω (T i , P i );

[0047] ω、△T i , △P i , Q bω , △Q ω (T i , P i ) is combined into a piece of expansion and contraction error training data s ωi ;

[0048] 1-1-3) Obtain M1 pieces of expansion and contraction error training data corresponding to M1 groups of hydraulic oils with different temperatures and pressures under the valve opening angle ω, and combine them to obtain the expansion and contraction error training data subset s ω ;

[0049] 1-1-4) Obtain N1 sets of expansion / contraction error training data subsets at N1 different valve opening angles according to the methods of 1-1-1) - 1-1-3), and combine them to obtain the expansion / contraction error training data set S1;

[0050] 1-2) Use the expansion and contraction error training data set S1 to train the CNN network model, with ω, △T i , △P i , Q bω is the input, △Q ω (T i , P i ) is the target output, and the oil expansion and contraction flow error prediction submodule is obtained after the training is completed.

[0051] Preferably, the motor creep flow error prediction submodule is constructed by the following method:

[0052] 2-1) Construct crawling error training dataset S2:

[0053] 2-1-1) When the motor is running at any speed r j Under the working condition of inputting hydraulic oil into the first hydraulic oil chamber, the following data are obtained:

[0054] The flow rate of the hydraulic oil detected by the flow meter within the time t after the controller issues the command to stop the motor is the motor creep flow increment △Q rj , and obtain the hydraulic oil temperature T at this time j , pressure P j , r j 、T j 、P j , △Q rj Combined into a crawling error training data S rj ;

[0055] Where, t = 0.5-120s;

[0056] 2-1-2) Change the temperature and pressure of the hydraulic oil, obtain M2 sets of crawling error training data corresponding to hydraulic oils of different temperatures and pressures, and combine them to obtain the crawling error training data subset S r ;

[0057] 2-1-3) Obtain N2 groups of creep error training data subsets at N2 different motor speeds according to the methods of 2-1-1) - 2-1-2), and combine them to obtain the creep error training data set S2;

[0058] 2-2) With r j 、T j 、P j is the input, △Q rjAs the target output, the DBN network model is trained using the creeping error training data set S2. After the training is completed, the motor creeping flow error prediction submodule is obtained.

[0059] Preferably, in step S1-2, the oil flow correction module corrects the flow Q Lθ The method for making the initial correction is:

[0060] The control module inputs the valve opening angle θ, the temperature value T0 of the hydraulic oil detected by the temperature sensor, and the pressure value P0 of the hydraulic oil detected by the pressure sensor into the data preprocessing submodule, and the data preprocessing submodule calculates the temperature difference ΔT0 and pressure difference ΔP0 between the actual hydraulic oil and the standard hydraulic oil: ΔT0=T0-T b , △P0=P0-P b Then, the valve opening angle θ, △T0, and △P0 are input into the oil expansion and contraction flow error prediction submodule to analyze and obtain the flow difference △Q θ (T0, P0);

[0061] The calculation output submodule calculates the initial correction flow Q' Lθ , Q' Lθ =Q Lθ -△Q θ (T0, P0).

[0062] Preferably, step S1-3 is specifically as follows:

[0063] The control module obtains the set speed r of the motor e The temperature value T0 of the hydraulic oil detected by the temperature sensor and the pressure value P0 of the hydraulic oil detected by the pressure sensor are input into the motor creep flow error prediction submodule, and the motor creep flow increment △Q is obtained by analysis. y ;

[0064] The calculation output submodule calculates the final corrected flow Q Sθ And output, Q Sθ =Q' Lθ -△Q y =Q Lθ -△Q θ (T0, P0)-△Q y .

[0065] The beneficial effects of the present invention are:

[0066] The single-acting electro-hydraulic actuator provided by the present invention has the function of self-closing when power is off. When the electro-hydraulic actuator is powered off, the elastic force of the disc spring can drive the valve to complete the automatic valve closing action (automatic reset valve closing) to ensure the power off safety of the valve;

[0067] In addition to the automatic reset valve closing function, the present invention also has an auxiliary rapid reset valve closing function. When rapid valve closing is required, the motor can be controlled to reverse and cooperate with the disc spring to achieve rapid valve closing in some special circumstances.

[0068] The single-acting electro-hydraulic actuator of the present invention utilizes the internal structure of the disc spring cylinder to form an oil storage space through structural optimization and design, thereby eliminating the need for a hydraulic oil tank, thereby reducing the size of the device and simplifying the piping.

[0069] The controller of the present invention uses a neural network model based on machine learning to analyze and predict historical data based on the expansion and contraction characteristics of hydraulic oil and other factors, as well as changes in parameters such as hydraulic oil pressure and temperature, to accurately predict the value of the oil expansion and contraction flow error. It then corrects the delivered hydraulic oil flow rate, thereby improving valve control accuracy.

[0070] In order to solve the motor creep flow incremental error caused by the motor "creep phenomenon" and the difference between the hydraulic oil flow and the preset value, the DBN network is used as the basic model framework and trained with data. The obtained model can achieve high-precision prediction of the motor creep flow error, thereby correcting the delivered hydraulic oil flow again, which can further improve the valve control accuracy, so that the single-acting electro-hydraulic actuator of the present invention can be well applied to valve control with high control accuracy requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 Schematic diagram of the internal structure of the single-acting electro-hydraulic actuator of the present invention;

[0072] Figure 2 Schematic diagram of the external structure of the single-acting electro-hydraulic actuator of the present invention;

[0073] Figure 3 A schematic diagram of the internal structure of a hydraulic cylinder of a single-acting electro-hydraulic actuator of the present invention;

[0074] Figure 4 A schematic diagram of the internal structure of a disc spring cylinder on one side of a single-acting electro-hydraulic actuator of the present invention;

[0075] Figure 5 Schematic diagram of the principle structure of the oil power mechanism of the present invention;

[0076] Figure 6 This is a flow chart of controlling the valve opening action in the present invention;

[0077] Figure 7 This is a flow chart of controlling the automatic resetting and closing valve action in the present invention;

[0078] Figure 8This is a flow chart of controlling the auxiliary rapid reset valve closing action in the present invention;

[0079] Figure 9 Schematic diagram of the principle structure of the controller of the present invention;

[0080] Figure 10 This is a flow chart of the valve opening method of the present invention;

[0081] Figure 11 Schematic diagram of the construction process of the oil expansion and contraction flow error prediction submodule of the present invention;

[0082] Figure 12 Schematic diagram of the construction process of the motor creep flow error prediction submodule of the present invention;

[0083] Figure 13 The test results of the hydraulic oil temperature between 35-45° C. in the test example of the present invention are as follows;

[0084] Figure 14 This is the test result when the temperature of the hydraulic oil is between 65-80°C in the test example of the present invention.

[0085] Description of reference numerals:

[0086] 1—Hydraulic cylinder; 10—Hydraulic cylinder head; 11—Gear shaft; 12—First oil port; 13—First oil delivery channel; 14—First internal oil guide port; 15—Second oil port; 16—Second oil delivery channel; 17—Second internal oil guide port; 18—Adjusting screw; 19—Nut;

[0087] 2—disc spring cylinder; 20—disc spring; 21—disc spring cylinder cover; 22—adjusting piston; 23—threaded rod; 24—adjusting shaft; 25—limiting cam; 26—piston head; 27—limiting hole; 28—limiting step surface;

[0088] 3—Rack piston rod; 30—Rack portion; 31—Front piston portion; 32—Rear piston portion;

[0089] 4—reset push rod; 40—sleeve portion; 41—annular convex portion; 42—top column portion; 43—oil storage channel; 44—first oil storage hole; 45—second oil storage hole;

[0090] 50—first hydraulic oil chamber; 51—second hydraulic oil chamber;

[0091] 6—guide hole;

[0092] 7—Hydraulic power mechanism; 700—First oil pipe; 701—First non-return valve; 702—Flow meter; 703—Oil pump; 704—Motor; 705—Second oil pipe; 706—Third oil pipe; 707—First solenoid valve; 708—Fourth oil pipe; 709—Temperature sensor; 710—Pressure sensor; 711—Controller; 712—Fifth oil pipe; 713—Second solenoid valve; 714—Second non-return valve; 715—Oil replenishing port; 716—Sixth oil pipe; 717—Exhaust valve; 718—Exhaust port. DETAILED DESCRIPTION

[0093] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0094] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0095] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the description, the following preferred embodiments of the present invention are described in detail with reference to the accompanying drawings. The specific implementation methods of the present invention are given in detail by the following embodiments and the accompanying drawings.

[0096] Example 1

[0097] Reference Figure 1-5 This embodiment provides a single-acting electro-hydraulic actuator for driving a valve to perform an opening and closing action. The single-acting electro-hydraulic actuator includes: a hydraulic cylinder 1, a hydraulic cylinder head 10 sealedly connected to a first end of the hydraulic cylinder 1, a disc spring cylinder 2 connected to a second end of the hydraulic cylinder 1, a rack piston rod 3 movably disposed axially within the hydraulic cylinder 1, a gear shaft 11 rotatably disposed on the hydraulic cylinder 1 and meshing with a rack portion 30 on the rack piston rod 3, a disc spring 20 disposed within the disc spring cylinder 2, a reset push rod 4 disposed within the disc spring cylinder 2 and having a first end extending into the hydraulic cylinder 1, a first oil port 12 and a second oil port 15 formed on the hydraulic cylinder 1, and an oil power mechanism 7 connected between the first oil port 12 and the second oil port 15.

[0098] The first and second ends of the rack piston rod 3 are respectively provided with a front piston portion 31 and a rear piston portion 32. The cavity between the front piston portion 31 and the hydraulic cylinder head 10 and the inner wall of the hydraulic cylinder 1 forms a first hydraulic oil chamber 50, and the cavity between the rear piston portion 32 and the inner wall of the hydraulic cylinder 1 forms a second hydraulic oil chamber 51. The first oil port 12 is connected to the first hydraulic oil chamber 50, and the second oil port 15 is connected to the second hydraulic oil chamber 51.

[0099] The disc spring 20 is arranged in cooperation with the reset push rod 4, so that under the elastic force of the disc spring 20, the first end of the reset push rod 4 has a pressing effect on the rear piston portion 32 toward the side of the hydraulic cylinder cover 10;

[0100] The oil power mechanism 7 realizes the function of conveying hydraulic oil between the first hydraulic oil chamber 50 and the second hydraulic oil chamber 51 through the first oil port 12 and the second oil port 15. When the hydraulic oil is input from the second hydraulic oil chamber 51 to the first hydraulic oil chamber 50, the pressure of the hydraulic oil causes the rack piston rod 3 to move linearly toward the side of the disc spring cylinder 2, thereby driving the gear shaft 11 to rotate counterclockwise, and finally driving the valve to open the valve; when the hydraulic oil is input from the first hydraulic oil chamber 50 to the second hydraulic oil chamber 51, the elastic force of the disc spring 20 causes the reset push rod 4 to push the rack piston rod 3 to move linearly toward the side of the hydraulic cylinder cover 10, thereby driving the gear shaft 11 to rotate clockwise, and finally driving the valve to close the valve.

[0101] In this embodiment, a first oil delivery channel 13 communicating with the first oil port 12, a first internal oil guide port 14 communicating with the end of the first oil delivery channel 13, a second oil delivery channel 16 communicating with the second oil port 15, and a second internal oil guide port 17 communicating with the end of the second oil delivery channel 16 are formed in the cylinder wall of the hydraulic cylinder 1. The first internal oil guide port 14 is communicated with the first hydraulic oil chamber 50, and the communication position is located on the side of the hydraulic cylinder head 10. The second internal oil guide port 17 is communicated with the second hydraulic oil chamber 51.

[0102] In this embodiment, the hydraulic cylinder head 10 is provided with an adjusting screw 18, the end of which extends into the first hydraulic oil chamber 50, and is used to adjust the rack piston rod 3 toward the side of the hydraulic cylinder head 10 by pressing the front piston portion 31 ( Figure 1 The adjusting screw 18 is provided with a nut 19 for locking the adjusting screw 18 after adjustment.

[0103] In the following description, the side of the hydraulic cylinder cover 10 is referred to as the left side and the side of the disc spring cylinder 2 is referred to as the right side for ease of description.

[0104] The inner end of the adjusting screw 18 must always protrude from the inner wall of the hydraulic cylinder head 10 to ensure that when the rack piston rod 3 moves toward the hydraulic cylinder head 10 to the extreme position, a certain gap remains between the front piston portion 31 and the inner wall of the hydraulic cylinder head 10. The first inner oil guide port 14 is connected to this gap, thereby ensuring that hydraulic oil can smoothly enter the first hydraulic oil chamber 50. By adjusting the length of the adjusting screw 18 extending into the first hydraulic oil chamber 50, the extreme position of the rack piston rod moving toward the hydraulic cylinder head 10 can be adjusted, and the valve closing angle can be adjusted.

[0105] The front piston portion 31 and the rear piston portion 32 of the rack piston rod 3 are both sealed against the inner wall of the hydraulic cylinder 1 , and the adjusting screw 18 is sealed against the hydraulic cylinder cover 10 to ensure the sealing of the first hydraulic oil chamber 50 .

[0106] In this embodiment, the reset push rod 4 includes a sleeve portion 40 that can be slidably arranged in the disc spring cylinder 2 along the axial direction, a top column portion 42 connected to the first end of the sleeve portion 40 and extending into the hydraulic cylinder 1, and an annular convex portion 41 connected between the sleeve portion 40 and the top column portion 42. The annular convex portion 41 contacts the movable end of the disc spring 20, so that the disc spring 20 applies pressure to the annular convex portion 41 toward one side of the hydraulic cylinder head 10 ( Figure 1 The top pressure of the upper part (on the left side of the center) provides the reset driving force.

[0107] A guide hole 6 is formed in the middle of the connection position between the hydraulic cylinder 1 and the disc spring cylinder 2, and the top column portion 42 can slide through the guide hole 6. The guide hole 6 cooperates with the top column portion 42 to achieve a linear guide effect for resetting the ejector rod 4.

[0108] A first oil storage hole 44 is defined in the top column portion 42 , a second oil storage hole 45 communicating with the first oil storage chamber is defined in the sleeve portion 40 , and an oil storage channel 43 communicating with the first oil storage hole 44 and the second hydraulic oil chamber 51 is defined in the top column portion 42 .

[0109] The second inner oil guide port 17 is opened at a position close to the connection position between the hydraulic cylinder 1 and the disc spring cylinder 2. The hydraulic oil entering from the second oil port 15 enters the second hydraulic oil chamber 51 through the second oil delivery channel 16 and the second inner oil guide port 17, and then enters the first oil storage hole 44 and the second oil storage hole 45 in turn through the oil storage channel 43 for storage. Storing the hydraulic oil in the internal space of the disc spring cylinder 2 can eliminate the need for a hydraulic oil tank, thereby reducing the volume of the device and simplifying the pipeline.

[0110] Among them, when the rack piston rod 3 moves to the rear end toward the disc spring cylinder 2, the rear piston part 32 of the rack piston rod 3 is still at the left end of the second inner oil guide port 17 to ensure that the hydraulic oil can always smoothly enter the second hydraulic oil chamber 51.

[0111] In this embodiment, the second end of the disc spring cylinder 2 is sealedly connected to the disc spring cylinder cover 21. The disc spring cylinder cover 21 is provided with an adjusting piston 22 that extends into the disc spring cylinder 2. The adjusting piston 22 includes a threaded rod 23 threadedly connected to the disc spring cylinder cover 21, an adjusting shaft 24 connected to the threaded rod 23, a limiting flange 25 provided on the adjusting shaft 24, and a piston head 26 connected to the end of the adjusting shaft 24 and inserted into the second oil storage hole 45.

[0112] A limiting hole 27 having a diameter larger than that of the second oil storage hole 45 is provided at the end of the sleeve portion 40, and a limiting step surface 28 is formed between the limiting hole 27 and the second oil storage hole 45; the limiting protrusion 25 limits the extreme position of the reset push rod 4 moving toward the side of the disc spring cylinder cover 21 by cooperating with the pressing limiting step surface 28.

[0113] When the rack piston rod 3 moves to the right, the top column portion 42 is pressed, driving the entire reset push rod 4 to move to the right. When the sleeve portion 40 moves relative to the adjusting piston 22 and the limiting step surface 28 presses against the limiting ridge 25 of the limiting step surface 28, the rack piston rod 3 and the reset push rod 4 reach the right limit position. By rotating and adjusting the length of the adjusting piston 22 inserted into the disc spring cylinder 2, this limit position can be adjusted, thereby adjusting the maximum valve opening angle. For example, when the adjusting piston 22 is screwed further into the disc spring cylinder 2, the limiting ridge 25 will move a certain distance to the left, causing the right limit position of the rack piston rod 3 and the reset push rod 4 to move leftward, thereby reducing the maximum valve opening angle.

[0114] The guide hole 6 and the top column portion 42 are sealed, and the piston head 26 is always inserted into the second oil storage hole 45 and remains sealed, thereby ensuring the sealing of the second hydraulic oil chamber 51 .

[0115] The piston head 26 not only plays a sealing role, but also plays a certain linear guiding role for the sleeve portion 40 .

[0116] Reference Figure 5 In this embodiment, the oil power mechanism 7 includes a first oil pipe 700 connected to the first oil port 12, a first one-way valve 701 provided on the first oil pipe 700, a flow meter 702 provided on the first oil pipe 700 and located between the first oil port 12 and the first one-way valve 701, an oil pump 703 connected to the end of the first oil pipe 700, a motor 704 connected to the oil pump 703, a second oil pipe 705 connecting the oil pump 703 to the second oil port 15, a third oil pipe 706 connected between the first oil pipe 700 and the second oil pipe 705, a first solenoid valve 707 provided on the third oil pipe 706, a fourth oil pipe 708 connected to the first oil pipe 700, a temperature sensor 709 and a pressure sensor 710 provided on the fourth oil pipe 708, and a controller 711 connected to the motor 704;

[0117] The first one-way valve 701 allows the hydraulic oil to be transported from the oil pump 703 to the first oil port 12 , and blocks the reverse flow.

[0118] The connection position of the third oil pipe 706 and the first oil pipe 700 is between the flow meter 702 and the first one-way valve 701, and the connection position of the fourth oil pipe 708 and the first oil pipe 700 is between the flow meter 702 and the first one-way valve 701;

[0119] The controller 711 is communicatively connected to the flow meter 702 , the first solenoid valve 707 , the temperature sensor 709 , and the pressure sensor 710 , and can obtain the detection results of the flow meter 702 , the temperature sensor 709 , and the pressure sensor 710 in real time, and can control the first solenoid valve 707 .

[0120] The flow meter 702 is used to monitor the flow of the hydraulic oil pumped into and out of the first oil port 12 ; the temperature sensor 709 and the pressure sensor 710 are used to monitor the temperature and pressure of the hydraulic oil pumped into and out of the first oil port 12 , respectively.

[0121] In this embodiment, a fifth oil pipe 712 is further connected between the third oil pipe 706 and the first oil pipe 700. A second solenoid valve 713 is provided on the fifth oil pipe 712. The second solenoid valve 713 is in communication with the controller 711, and the second solenoid valve 713 can be controlled by the controller 711.

[0122] The connection position of the fifth oil pipe 712 and the third oil pipe 706 is between the first one-way valve 701 and the first solenoid valve 707 , and the connection position of the fifth oil pipe 712 and the first oil pipe 700 is between the first one-way valve 701 and the oil pump 703 .

[0123] A second check valve 714 is installed on the fourth oil pipe 708, and an oil replenishment port 715 is located at the end of the fourth oil pipe 708. The second check valve 714 only allows hydraulic oil to flow into the fourth oil pipe 708 through the oil replenishment port 715, and blocks reverse flow. The oil replenishment port 715 is used for the initial addition of hydraulic oil to the electro-hydraulic actuator and for subsequent oil replenishment during maintenance.

[0124] The second oil pipe 705 is connected to a sixth oil pipe 716, which is equipped with an exhaust valve 717. An exhaust port 718 is located at the end of the sixth oil pipe 716. Exhaust valve 717 only allows gas to escape from the sixth oil pipe 716 to the exhaust port 718, blocking the flow in the opposite direction and preventing the hydraulic oil from escaping. Exhaust port 718 is primarily used to discharge internal gas during the initial addition of hydraulic oil to the electro-hydraulic actuator and during subsequent refilling.

[0125] Among them, the first solenoid valve 707 and the second solenoid valve 713 are both normally closed valves, and both remain closed during the valve opening action; during the valve closing action, only one of them will be open. The subsequent embodiments will explain the control process in detail.

[0126] Example 2

[0127] This embodiment provides a control method for the controller 711 of the single-acting electro-hydraulic actuator of Example 1. The controller 711 includes a control module and an oil flow correction module. The controller 711 controls the motor 704 according to instructions, and then drives the oil pump 703 through the motor 704 to realize the valve switching action.

[0128] Similar to conventional electro-hydraulic actuators, the basic principle of the single-acting electro-hydraulic actuator of the present invention is to drive the delivery of hydraulic oil through motor 704, and utilize the pressure of the hydraulic oil to achieve the opening and closing action of the valve. The control of parameters such as the valve opening angle is monitored and controlled by controlling the flow rate of the hydraulic oil. Under ideal circumstances, it is assumed that the density of the hydraulic oil remains unchanged, that is, it is incompressible, and the flow rate (volume) of hydraulic oil required to drive the target mechanism (load) to move the same distance is fixed. However, under actual circumstances, when the hydraulic oil drives the load to move, it is subjected to pressure and will undergo a certain degree of compression during this process. This will cause the volume of the pumped hydraulic oil to change, causing errors in the actual distance the load moves, ultimately affecting the accuracy of the valve opening angle. When the temperature rises, the hydraulic oil will expand to a certain extent, which will also affect the valve control accuracy. For applications requiring precise control of the valve angle, the above-mentioned errors are generally not negligible.

[0129] For example, specifically in this embodiment, assuming that the flow rate of the hydraulic oil pumped into the first hydraulic oil chamber 50 required to make the valve opening angle θ is Q Lθ (equivalent to volume), ideally, the flow rate of the hydraulic oil pumped into the first hydraulic oil chamber 50 is monitored by the flow meter 702 to reach Q Lθ When the rack piston rod 3 moves to the right by the design distance L, L corresponds to the valve opening angle θ. However, in actual conditions, the volume Q Lθ After the hydraulic oil enters the first hydraulic oil chamber 50, it will be compressed under the action of pressure, resulting in the actual volume Q' of the hydraulic oil. Lθ Less than Q Lθ , so that the distance the rack piston rod 3 moves to the right is less than the designed distance L, which ultimately causes the valve opening angle to be less than θ. The temperature of the hydraulic oil also has a certain influence on the expansion and contraction characteristics of the hydraulic oil. When the temperature rises, the hydraulic oil will expand, and the compression amount of the above process will be affected. In other words, the volume Q Lθ After the hydraulic oil is pumped into the first hydraulic oil chamber 50, the actual volume of the hydraulic oil will change due to the expansion and contraction characteristics of the hydraulic oil. Lθ There is a difference between them, which is the error (in this embodiment, Q Lθ With Q' LθThe difference between them is called oil expansion and contraction flow error), and the hydraulic oil flow, temperature and pressure have a great influence on this error. Reducing this error can improve valve control accuracy.

[0130] On the other hand, similar to the traditional solution, the present invention also uses motor 704 to drive the oil pump 703 to transport hydraulic oil. The motor usually has a certain "creeping phenomenon" (the motor still maintains a certain speed under zero voltage conditions, that is, after the motor is controlled to stop rotating, the motor will still rotate for a certain period of time before finally stopping). This phenomenon will cause the motor to still make the oil pump 703 work for a short period of time after the motor stops, thereby causing the flow rate of the hydraulic oil to increase than the preset flow rate. In the present invention, this increased flow rate is called the motor creep flow increment. The error caused by this increment will also affect the precise control of the valve.

[0131] In this embodiment, the above-mentioned oil expansion and contraction flow error and motor creep flow increment error can be effectively reduced through the improvement of the solution. The specific method in this embodiment is described in detail below.

[0132] In this embodiment, the control method of the controller 711 includes:

[0133] S1, valve opening action:

[0134] S1-1. The controller 711 obtains the valve opening angle θ (i.e., the target valve opening angle) according to the instruction, and calculates the flow rate Q of the hydraulic oil pumped into the first hydraulic oil chamber 50 required for the valve opening angle θ. Lθ ;

[0135] When the valve needs to be opened to an angle θ, the distance L that the rack piston rod 3 needs to move to the right can be calculated using the design parameters of the single-acting electro-hydraulic actuator. After knowing the design parameters such as the cross-sectional area of ​​the hydraulic cylinder 1 and the volume of the pipeline, the volume of hydraulic oil required to move the rack piston rod 3 to the right by the distance L can be calculated using conventional methods, that is, its flow rate Q. Lθ .

[0136] S1-2, the oil flow correction module adjusts the flow Q according to the detection results of the temperature sensor 709 and the pressure sensor 710. Lθ Perform the initial correction to obtain the initial correction flow Q' Lθ ;

[0137] S1-3, the oil flow correction module then adjusts the speed of the motor 704 according to the set speed r e The detection results of the temperature sensor 709 and the pressure sensor 710 are analyzed and calculated to calculate the motor creep flow increment △Q y ; Then correct the initial flow Q' Lθ Make correction again to get the final correction flow QSθ , Q Sθ =Q' Lθ -△Q y ;

[0138] S1-4, the controller 711 controls the motor 700 to rotate at a set speed r e When the flow meter 702 detects that the flow rate of the hydraulic oil pumped into the first hydraulic oil chamber 50 reaches Q Sθ When the motor 704 is controlled to stop working;

[0139] Among them, after the hydraulic oil enters the first hydraulic oil chamber 50 through the first oil port 12, the pressure of the hydraulic oil causes the rack piston rod 3 to move linearly toward the side of the disc spring cylinder 2, driving the gear shaft 11 to rotate counterclockwise, thereby driving the valve to open the valve; refer to Figure 6 and Figure 10 ;

[0140] S2, valve closing action:

[0141] The control method for closing the valve is either of the following two methods:

[0142] S2-1, automatic reset valve closing:

[0143] Reference Figure 7 When the valve is closed, the controller 711 controls the oil pump 703 to stop working and controls the first solenoid valve 707 to open, so that the first oil port 12 and the second oil port 15 are connected; at this time, the second solenoid valve 713 remains closed, and the first one-way valve 701 can prevent the hydraulic oil from flowing to the oil pump 703;

[0144] Under the elastic force of the disc spring 20, the reset push rod 4 moves linearly toward the side of the hydraulic cylinder head 10 and presses the rear piston portion 32 of the rack piston rod 3, causing the rack piston rod 3 to move linearly toward the side of the hydraulic cylinder head 10, driving the gear shaft 11 to rotate clockwise until the front piston portion 31 of the rack piston contacts the adjusting screw 18 and stops, thereby driving the valve to complete the valve closing action;

[0145] S2-2, auxiliary rapid reset valve closing:

[0146] Reference Figure 8 When the valve is closed, the controller 711 controls the first electromagnetic valve 707 to close and the second electromagnetic valve 713 to open, and controls the motor 704 to rotate at the set speed r e Reverse rotation works, pumping the hydraulic oil in the first hydraulic oil chamber 50 into the second hydraulic oil chamber 51. When the flow meter 702 detects that the flow rate of the hydraulic oil pumped out of the first hydraulic oil chamber 50 reaches Q Sθ When the motor 704 is controlled to stop working;

[0147] Hydraulic oil flows from the first hydraulic oil chamber 50 into the second hydraulic oil chamber 51. Simultaneously, the elastic force of the disc spring 20 causes the rack piston rod 3 to move linearly toward the cylinder head 10, driving the gear shaft 11 to rotate clockwise, thereby closing the valve. Because the oil pump 703 rapidly replaces the hydraulic oil in the first and second hydraulic oil chambers 50, 51, it cooperates with the disc spring to accelerate the valve closing process.

[0148] In this embodiment, under normal circumstances, the automatic reset valve closing control method is preferred. The automatic valve closing can be completed through the elastic force of the disc spring 20, reducing the electromechanical fatigue damage caused by the alternating forward and reverse operation of the motor 704, so as to extend the service life of the equipment. At the same time, the control method is also simpler.

[0149] In this embodiment, the first solenoid valve 707 is a normally closed valve. When the electro-hydraulic actuator is powered off, the first solenoid valve 707 will lose power and open, so that the elastic force of the disc spring 20 will eventually drive the valve to complete the closing of the valve to ensure the power-off safety of the valve.

[0150] In this embodiment, the second solenoid valve is a normally closed valve.

[0151] In this embodiment, when rapid valve closing is required, an auxiliary rapid reset valve closing control method is adopted, and the motor 704 is reversed to accelerate the delivery of hydraulic oil from the first hydraulic oil chamber 50 to the second hydraulic oil chamber 51, thereby increasing the valve closing speed and achieving rapid valve closing in some special circumstances.

[0152] Reference Figure 9 In this embodiment, the oil flow correction module includes a data preprocessing submodule, an oil expansion and contraction flow error prediction submodule, a motor creep flow error prediction submodule, and a calculation output submodule;

[0153] The oil expansion and contraction flow error prediction submodule and the motor creep flow error prediction submodule both use a method based on machine learning algorithms for error prediction;

[0154] Reference Figure 11 ,The oil expansion and contraction flow error prediction submodule is constructed by the following method:

[0155] 1-1) Construct the expansion and contraction error training dataset S1:

[0156] 1-1-1) For any valve opening angle ω, calculate the flow rate Q of the hydraulic oil in the standard state required to be pumped into the first hydraulic oil chamber 50 corresponding to the valve opening angle ω bω ; The temperature of the hydraulic oil in the standard state is T b , pressure is P b ;

[0157] 1-1-2) Corresponding to the valve opening angle ω, determine any temperature T through experiment i , pressure P i The actual flow rate Q of the hydraulic oil required to be pumped into the first hydraulic oil chamber 50 ω (T i , P i ), calculate the temperature difference △T between the actual hydraulic oil and the standard hydraulic oil i , pressure difference △P i and flow difference △Q ω (T i , P i ):

[0158] △T i =T i -T b , △P i =P i -P b , △Q ω (T i , P i ) = Q bω -Q ω (T i , P i );

[0159] ω、△T i , △P i , Q bω , △Q ω (T i , P i ) is combined into a piece of expansion and contraction error training data s ωi ;

[0160] 1-1-3) Obtain M1 pieces of expansion and contraction error training data corresponding to M1 groups of hydraulic oils with different temperatures and pressures under the valve opening angle ω, and combine them to obtain the expansion and contraction error training data subset s ω ;

[0161] The value of M1 is selected according to the actual situation. The larger the value, the larger the data volume, the higher the model accuracy will be in theory, but the amount of calculation will also be larger, so it is necessary to select an appropriate value, for example, M1=100-10000, in this embodiment, M1=1000.

[0162] 1-1-4) Obtain N1 sets of expansion / contraction error training data subsets at N1 different valve opening angles according to the methods of 1-1-1) - 1-1-3), and combine them to obtain the expansion / contraction error training data set S1;

[0163] The value of N1 is selected according to the actual situation. The larger the value, the larger the data volume, and the higher the model accuracy will be in theory, but the amount of calculation will also be greater, so it is necessary to select an appropriate value. For example, N1=12-360. In this embodiment, N1=90, and 90 different angles are taken between 0° and 180° (for example, starting from 0°, an angle value is taken at intervals of 2°).

[0164] 1-2) Use the expansion and contraction error training data set S1 to train the CNN network model (Convolutional Neural Networks) with ω, △T i , △P i , Q bω is the input, △Q ω (T i , P i ) is the target output, and after the training is completed, the oil expansion and contraction flow error prediction submodule is obtained.

[0165] The oil expansion and contraction flow error is a nonlinear error, which is mainly affected by factors such as the valve opening angle (different valve opening angles correspond to different hydraulic oil flows), hydraulic oil pressure, temperature, etc. Through a neural network model based on machine learning and analysis and prediction based on historical data, the value of the oil expansion and contraction flow error can be predicted more accurately, thereby improving the valve control accuracy.

[0166] Reference Figure 12 In this embodiment, the motor creep flow error prediction submodule is constructed by the following method:

[0167] 2-1) Construct crawling error training dataset S2:

[0168] 2-1-1) When the motor 704 is running at any speed r j Under the working condition of inputting hydraulic oil into the first hydraulic oil chamber 50, the following data are obtained:

[0169] The flow rate of the hydraulic oil detected by the flow meter 702 within the time t after the controller 711 issues the instruction to stop the motor 704 is the motor creep flow increment ΔQ rj , and obtain the hydraulic oil temperature T at this time j , pressure P j , r j 、T j 、P j , △Q rj Combined into a crawling error training data S rj ;

[0170] The value of t can be selected according to the situation, for example, t=0.5-120s; in this embodiment, t=5s;

[0171] 2-1-2) Change the temperature and pressure of the hydraulic oil, obtain M2 sets of crawling error training data corresponding to hydraulic oils of different temperatures and pressures, and combine them to obtain the crawling error training data subset S r ;

[0172] The value of M2 is selected according to the actual situation. The larger the value, the larger the data volume, the higher the model accuracy will be in theory, but the amount of calculation will also be larger, so it is necessary to select an appropriate value, for example, M1=200-20000, in this embodiment, M2=2000.

[0173] 2-1-3) Obtain N2 sets of creep error training data subsets at N2 different motor 704 speeds according to the methods of 2-1-1) - 2-1-2), and combine them to obtain a creep error training data set S2;

[0174] The value of N2 is selected according to the actual situation. The larger the value, the larger the data volume, and the higher the model accuracy will be in theory, but the amount of calculation will also be greater. Therefore, it is necessary to select an appropriate value. For example, N2=50-2000. In this embodiment, N2=500, and 500 values ​​are taken within the speed range of 100-8000 rpm (for example, starting from 200 rpm, a speed value is taken every 10 rpm).

[0175] 2-2) With r j 、T j 、P j is the input, △Q rj As the target output, the DBN network model is trained using the creeping error training dataset S2. After the training is completed, the motor creeping flow error prediction submodule is obtained.

[0176] The motor creep flow error is also a nonlinear error, which is mainly affected by factors such as the operating speed of motor 704 before shutdown, the temperature and pressure of the hydraulic oil being transported, etc. The DBN network (Deep Belief Networks) is used as the basic model framework and trained with a large amount of historical data. The resulting model can achieve high-precision prediction of the motor creep flow error, thereby further improving the valve control accuracy.

[0177] It should be understood that the control accuracy of the valve is mainly the accuracy of the valve opening angle, and the valve only needs to be completely closed during the valve closing process, so the oil flow correction module is mainly used to correct errors during the valve opening process.

[0178] In this embodiment, in step S1-2, the oil flow correction module adjusts the flow Q Lθ The method for making the initial correction is:

[0179] The control module inputs the valve opening angle θ, the hydraulic oil temperature value T0 detected by the temperature sensor 709, and the hydraulic oil pressure value P0 detected by the pressure sensor 710 into the data preprocessing submodule, and the data preprocessing submodule calculates the temperature difference △T0 and pressure difference △P0 between the actual hydraulic oil and the standard hydraulic oil: △T0=T0-T b , △P0=P0-P b Then, the valve opening angle θ, △T0, and △P0 are input into the oil expansion and contraction flow error prediction submodule to analyze and obtain the flow difference △Q θ (T0, P0);

[0180] The calculation output submodule calculates the initial correction flow Q' Lθ , Q' Lθ =Q Lθ -△Q θ (T0, P0).

[0181] In this embodiment, step S1-3 is specifically as follows:

[0182] The control module obtains the set speed r of the motor 704 e The temperature value T0 of the hydraulic oil detected by the temperature sensor 709 and the pressure value P0 of the hydraulic oil detected by the pressure sensor 710 are input into the motor creep flow error prediction submodule, and the motor creep flow increment △Q is obtained by analysis. y ;

[0183] The calculation output submodule calculates the final corrected flow Q Sθ And output, Q Sθ =Q' Lθ -△Q y =Q Lθ -△Q θ (T0, P0)-△Q y .

[0184] Test example:

[0185] Control method for comparison example:

[0186] S1, valve opening action:

[0187] S1-1, the controller 711 obtains the valve opening angle θ according to the instruction, and calculates the flow rate Q of the hydraulic oil pumped into the first hydraulic oil chamber 50 required for the valve opening angle θ Lθ ;

[0188] S1-2, the controller 711 controls the motor 700 to rotate at a set speed r e When the flow meter 702 detects that the flow rate of the hydraulic oil pumped into the first hydraulic oil chamber 50 reaches QSθ When the motor 704 is controlled to stop working.

[0189] That is, the control example adopts the same control method as the conventional solution, which does not consider the influence of the oil expansion and contraction flow error and the motor creep flow increment error.

[0190] The control methods of Example 2 and the comparative example were used to control the valve opening. The valve control accuracy η was tested at different target valve opening angles (5°, 10°, 30°, 45°, 60°, 90°, 120°, and 180°). In test process 1, the hydraulic oil temperature fluctuated between 30±1°C. In test process 2, the hydraulic oil temperature fluctuated between 80±1°C.

[0191] ,θ T is the target valve opening angle, θ S is the actual valve opening angle.

[0192] The test results are shown in Table 1 and Figure 13-14 As shown:

[0193] Table 1

[0194]

[0195] From the above test results, it can be seen that compared with the traditional method of the control example, the method of Example 2 can effectively improve the valve control accuracy; and when the operating temperature of the hydraulic oil is higher, the control accuracy of the control example tends to be lower, while the method of Example 2 still has a very high control accuracy; This shows that the solution of the present invention can be well applied to valve control with high control accuracy requirements.

[0196] The above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and the above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. Any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A single-acting electro-hydraulic actuator, which is used to drive a valve to perform an opening and closing action, characterized in that: The single-acting electro-hydraulic actuator includes: a hydraulic cylinder, a hydraulic cylinder cover sealedly connected to a first end of the hydraulic cylinder, a disc spring cylinder connected to a second end of the hydraulic cylinder, a rack piston rod movably disposed axially within the hydraulic cylinder, a gear shaft rotatably disposed on the hydraulic cylinder and meshing with a rack portion on the rack piston rod, a disc spring disposed within the disc spring cylinder, a reset ejector rod disposed within the disc spring cylinder and having a first end extending into the hydraulic cylinder, a first oil port and a second oil port provided on the hydraulic cylinder, and an oil power mechanism connected between the first oil port and the second oil port. The first end and the second end of the rack piston rod are respectively provided with a front piston portion and a rear piston portion, the cavity between the front piston portion and the hydraulic cylinder cover and the inner wall of the hydraulic cylinder forms a first hydraulic oil chamber, and the cavity between the rear piston portion and the inner wall of the hydraulic cylinder forms a second hydraulic oil chamber; the first oil port is connected to the first hydraulic oil chamber, and the second oil port is connected to the second hydraulic oil chamber; The disc spring is arranged in cooperation with the reset push rod, so that under the elastic force of the disc spring, the first end of the reset push rod has a pressing effect on the rear piston portion toward the side of the hydraulic cylinder cover; The oil power mechanism realizes the function of conveying hydraulic oil between the first hydraulic oil chamber and the second hydraulic oil chamber through the first oil port and the second oil port. When the hydraulic oil is input from the second hydraulic oil chamber into the first hydraulic oil chamber, the pressure of the hydraulic oil causes the rack piston rod to move linearly toward the side of the disc spring cylinder, driving the gear shaft to rotate counterclockwise, thereby driving the valve to open the valve; when the hydraulic oil is input from the first hydraulic oil chamber into the second hydraulic oil chamber, the elastic force of the disc spring causes the reset push rod to push the rack piston rod to move linearly toward the side of the hydraulic cylinder cover, driving the gear shaft to rotate clockwise, thereby driving the valve to close the valve; A guide hole is formed in the middle of the connection position between the hydraulic cylinder and the disc spring cylinder; The reset push rod includes a sleeve portion slidably arranged in the disc spring cylinder along the axial direction, a top column portion connected to the first end of the sleeve portion and extending into the hydraulic cylinder, and an annular convex portion connected between the sleeve portion and the top column portion, the annular convex portion contacts the movable end of the disc spring, and the top column portion is slidable through the guide hole; A first oil storage hole is provided in the top column portion, a second oil storage hole communicating with the first oil storage hole is provided in the sleeve portion, and an oil storage channel communicating with the first oil storage hole and the second hydraulic oil chamber is provided in the top column portion.

2. The single-acting electro-hydraulic actuator according to claim 1, characterized in that: The cylinder wall of the hydraulic cylinder is provided with a first oil delivery channel connected to the first oil port, a first internal oil guide port connected to the end of the first oil delivery channel, a second oil delivery channel connected to the second oil port, and a second internal oil guide port connected to the end of the second oil delivery channel. The first internal oil guide port is connected to the first hydraulic oil chamber, and the connection position is located on the side of the hydraulic cylinder cover. The second internal oil guide port is connected to the second hydraulic oil chamber.

3. The single-acting electro-hydraulic actuator according to claim 2, characterized in that: The hydraulic cylinder cover is provided with an adjusting screw, the end of which extends into the first hydraulic oil chamber to limit the extreme position of the linear motion of the rack piston rod toward the side of the hydraulic cylinder cover by pressing the front piston part.

4. The single-acting electro-hydraulic actuator according to claim 3, characterized in that: The second end of the disc spring cylinder is sealed with a disc spring cylinder cover, and the disc spring cylinder cover is provided with an adjusting piston extending into the disc spring cylinder, and the adjusting piston includes a threaded rod threadedly connected to the disc spring cylinder cover, an adjusting shaft connected to the threaded rod, a limiting convex edge provided on the adjusting shaft, and a piston head connected to the end of the adjusting shaft and inserted into the second oil storage hole; A limiting hole with a diameter larger than that of the second oil storage hole is provided at the end of the sleeve portion, and a limiting step surface is formed between the limiting hole and the second oil storage hole; the limiting convex edge limits the limit position of the reset push rod moving toward the side of the disc spring cylinder cover by cooperating to press the limiting step surface.

5. The single-acting electro-hydraulic actuator according to claim 4, characterized in that: The oil power mechanism includes a first oil pipe connected to the first oil port, a first one-way valve provided on the first oil pipe, a flow meter provided on the first oil pipe and located between the first oil port and the first one-way valve, an oil pump connected to an end of the first oil pipe, a motor connected to the oil pump, a second oil pipe connecting the oil pump to the second oil port, a third oil pipe connected between the first oil pipe and the second oil pipe, a first solenoid valve provided on the third oil pipe, a fourth oil pipe connected to the first oil pipe, a temperature sensor and a pressure sensor provided on the fourth oil pipe, and a controller connected to the motor; The connection position of the third oil pipe and the first oil pipe is between the flow meter and the first one-way valve, and the connection position of the fourth oil pipe and the first oil pipe is between the flow meter and the first one-way valve; The controller is in communication connection with the flow meter, the first solenoid valve, the temperature sensor, and the pressure sensor.

6. The single-acting electro-hydraulic actuator according to claim 5, characterized in that: A fifth oil pipe is further connected between the third oil pipe and the first oil pipe, and a second solenoid valve is provided on the fifth oil pipe, and the second solenoid valve is communicatively connected to the controller; The connection position of the fifth oil pipe and the third oil pipe is between the first one-way valve and the first solenoid valve, and the connection position of the fifth oil pipe and the first oil pipe is between the first one-way valve and the oil pump; The fourth oil pipe is provided with a second one-way valve, and the end of the fourth oil pipe is provided with an oil replenishing port; The second oil pipe is connected to a sixth oil pipe, the sixth oil pipe is provided with an exhaust valve, and the end of the sixth oil pipe is provided with an exhaust port.

7. The single-acting electro-hydraulic actuator according to claim 6, characterized in that: The controller includes a control module and an oil flow correction module. The controller controls the motor according to the instruction, and then drives the oil pump through the motor to realize the valve opening and closing action. The control method of the controller includes: S1, valve opening action: S1-1, the controller obtains the valve opening angle θ according to the instruction, and calculates the flow rate Q of the hydraulic oil pumped into the first hydraulic oil chamber required for the valve opening angle θ Lθ ; S1-2, the oil flow correction module adjusts the flow Q according to the detection results of the temperature sensor and the pressure sensor. Lθ Perform the initial correction to obtain the initial correction flow Q' Lθ ; S1-3, the oil flow correction module then adjusts the oil flow rate according to the set speed r of the motor. e And the detection results of temperature sensor and pressure sensor are analyzed to calculate the motor creep flow increment △Q y ; Then correct the initial flow Q' Lθ Make correction again to get the final corrected flow Q Sθ , Q Sθ =Q' Lθ -△Q y ; S1-4, the controller controls the motor to rotate at a set speed r e When the flow meter detects that the flow rate of the hydraulic oil pumped into the first hydraulic oil chamber reaches Q Sθ When the motor stops working; Among them, after the hydraulic oil enters the first hydraulic oil chamber through the first oil port, the pressure of the hydraulic oil causes the rack piston rod to move linearly toward the side of the disc spring cylinder, driving the gear shaft to rotate counterclockwise, thereby driving the valve to open the valve; S2, valve closing action: The control method for closing the valve is either of the following two methods: S2-1, automatic reset valve closing: When the valve is closed, the controller controls the oil pump to stop working and controls the first solenoid valve to open, so that the first oil port and the second oil port are connected; Under the elastic force of the disc spring, the reset push rod moves linearly toward the side of the hydraulic cylinder cover and presses the rear piston part of the rack piston rod, so that the rack piston rod moves linearly toward the side of the hydraulic cylinder cover, driving the gear shaft to rotate clockwise until the front piston part of the rack piston contacts the adjusting screw and stops, thereby driving the valve to complete the valve closing action; S2-2, auxiliary rapid reset valve closing: When closing the valve, the controller controls the first solenoid valve to close and the second solenoid valve to open, and controls the motor to rotate at the set speed r e Reverse rotation works, pumping the hydraulic oil in the first hydraulic oil chamber into the second hydraulic oil chamber. When the flow meter detects that the flow rate of the hydraulic oil pumped out of the first hydraulic oil chamber reaches Q Sθ When the motor stops working; Among them, the hydraulic oil enters the second hydraulic oil chamber from the first hydraulic oil chamber, and at the same time, under the elastic force of the disc spring, the rack piston rod moves linearly toward the side of the hydraulic cylinder head, driving the gear shaft to rotate clockwise, thereby driving the valve to complete the valve closing action.

8. The single-acting electro-hydraulic actuator according to claim 7, characterized in that: The oil flow correction module includes a data preprocessing submodule, an oil expansion and contraction flow error prediction submodule, a motor creep flow error prediction submodule and a calculation output submodule; The oil expansion and contraction flow error prediction submodule and the motor creep flow error prediction submodule both use a method based on a machine learning algorithm to perform error prediction; The oil expansion and contraction flow error prediction submodule is constructed by the following method: 1-1) Construct the expansion and contraction error training dataset S1: 1-1-1) For any valve opening angle ω, calculate the standard hydraulic oil flow rate Q required to be pumped into the first hydraulic oil chamber corresponding to the valve opening angle ω bω ; The temperature of the hydraulic oil in the standard state is T b , pressure is P b ; 1-1-2) Corresponding to the valve opening angle ω, determine any temperature T through experiment i , pressure P i The actual flow rate Q of the hydraulic oil required to be pumped into the first hydraulic oil chamber ω (T i , P i ), calculate the temperature difference △T between the actual hydraulic oil and the standard hydraulic oil i , pressure difference △P i and flow difference △Q ω (T i , P i ): △T i =T i -T b ,△P i =P i -P b ,△Q ω (T i ,P i )=Q bω -Q ω (T i ,P i ); ω、△T i , △P i , Q bω , △Q ω (T i , P i ) is combined into a piece of expansion and contraction error training data s ωi ; 1-1-3) Obtain M1 pieces of expansion and contraction error training data corresponding to M1 groups of hydraulic oils with different temperatures and pressures under the valve opening angle ω, and combine them to obtain the expansion and contraction error training data subset s ω ; 1-1-4) Obtain N1 sets of expansion / contraction error training data subsets at N1 different valve opening angles according to the methods of 1-1-1) - 1-1-3), and combine them to obtain the expansion / contraction error training data set S1; 1-2) Use the expansion and contraction error training data set S1 to train the CNN network model, with ω, △T i , △P i , Q bω is the input, △Q ω (T i , P i ) is the target output, and the oil expansion and contraction flow error prediction submodule is obtained after the training is completed.

9. The single-acting electro-hydraulic actuator according to claim 8, characterized in that: The motor creep flow error prediction submodule is constructed by the following method: 2-1) Construct crawling error training dataset S2: 2-1-1) When the motor is running at any speed r j Under the working condition of inputting hydraulic oil into the first hydraulic oil chamber, the following data are obtained: The flow rate of the hydraulic oil detected by the flow meter within the time t after the controller issues the command to stop the motor is the motor creep flow increment △Q rj , and obtain the hydraulic oil temperature T at this time j , pressure P j , r j 、T j 、P j , △Q rj Combined into a crawling error training data S rj ; Where, t = 0.5-120s; 2-1-2) Change the temperature and pressure of the hydraulic oil, obtain M2 sets of crawling error training data corresponding to hydraulic oils of different temperatures and pressures, and combine them to obtain the crawling error training data subset S r ; 2-1-3) Obtain N2 groups of creep error training data subsets at N2 different motor speeds according to the methods of 2-1-1) - 2-1-2), and combine them to obtain the creep error training data set S2; 2-2) With r j 、T j 、P j is the input, △Q rj As the target output, the DBN network model is trained using the creeping error training data set S2. After the training is completed, the motor creeping flow error prediction submodule is obtained.

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