Micro electro hydraulic actuator

Abstract

The application discloses a micro electro-hydraulic actuator, which comprises a shell, a micro pump matched and inserted into the upper part of the shell, a servo cylinder matched and inserted into the lower part of the shell, the servo cylinder comprising a hydraulic cylinder and a torque motor, the hydraulic cylinder being inserted into the shell, comprising a piston sleeve with steps inserted into the shell and a piston rod inserted into the piston sleeve, and the torque motor being arranged on one side of the hydraulic cylinder and being matched and connected with the piston rod; a brushless motor is arranged above the torque motor, the brushless motor is matched and connected with the micro pump inserted into the shell, the micro pump in the shell is matched and connected with the hydraulic cylinder, the brushless motor and the servo cylinder are respectively connected with a controller, the rotation speed of the brushless motor is adjusted through the controller so as to adjust the outlet flow of the micro pump, the rotation angle of the armature of the torque motor is adjusted through the controller so as to control the displacement of the servo cylinder, the displacement of the piston rod of the hydraulic cylinder is adjusted through the working of the micro pump driven by the brushless motor, and / or the displacement of the piston rod is adjusted through the adjustment of the input signal of the torque motor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of actuators, and particularly relates to a micro electro-hydraulic actuator. BACKGROUND

[0002] The electro-hydraulic actuator is a power unit integrated by a motor, a hydraulic pump, a hydraulic control element, a hydraulic actuating element, etc., which has the advantages of high power-to-weight ratio, high reliability, high efficiency inherent to the hydraulic system, and the advantages of high integration degree, fast response speed, high control precision specific to the electro-hydraulic actuator.

[0003] At present, the electro-hydraulic actuator is generally divided into pump control and valve control two control modes. The pump control system controls the output flow of the pump by changing the displacement of the pump, so as to adjust the movement speed of the actuating element. The pump control system has no flow control valve, and the energy consumption is relatively low, but the system response speed is slow and the control precision is low due to the low frequency response of the hydraulic pump. The valve control system controls the movement speed of the actuating element by controlling the opening size of the hydraulic valve (generally a servo valve or a proportional servo valve), and the system has high precision and fast response speed, but generally uses a fixed displacement pump, and the output of the pump is too much oil which is discharged through the overflow valve, so the energy consumption is relatively high.

[0004] The electro-hydraulic actuator is widely used in industries with high requirements for mass and volume, such as aerospace and robots. For example, the micro electro-hydraulic actuator can be used in aircraft actuation systems, which require lightness, small size and large output power; it can also be used in space station power systems and damping adjustment systems; it can be used as a micro driving system and a buffer system at the joint of a micro robot; therefore, the requirements for the volume and weight of the electro-hydraulic actuator are also extremely high.

[0005] Therefore, the micro electro-hydraulic actuator with the characteristics of miniaturization, high frequency response, high precision and low energy consumption is the development trend in the future. SUMMARY

[0006] The present application aims to provide a micro electro-hydraulic actuator which can have the pump control mode, the valve control mode and the combined mode of pump control and valve control synchronous work, and has the characteristics of high precision and fast dynamic of the servo valve, and at the same time, through pump control synchronous compensation, the system has low energy consumption and high efficiency, and also has high precision and high frequency response. The technical problem that the existing electro-hydraulic actuator cannot have both high precision and low energy consumption is solved. In order to achieve the purpose, the specific technical scheme of the present application is as follows:

[0007] The micro electro-hydraulic actuator comprises a shell, a micro pump inserted into the upper part of the shell, and a servo cylinder inserted into the lower part of the shell. The servo cylinder comprises a hydraulic cylinder and a torque motor. The hydraulic cylinder is inserted into the shell and comprises a piston sleeve and a piston rod. The torque motor is arranged on one side of the hydraulic cylinder and is connected with the piston rod. A brushless motor is arranged above the torque motor and is connected with the micro pump inserted into the shell. The micro pump in the shell is connected with the hydraulic cylinder. The brushless motor and the servo cylinder are respectively connected with a controller. The controller is used to adjust the rotation speed of the brushless motor to adjust the outlet flow of the micro pump, and to adjust the rotation angle of the armature of the torque motor to control the displacement of the servo cylinder, so as to adjust the displacement of the piston rod of the hydraulic cylinder by driving the micro pump by the brushless motor and / or to adjust the displacement of the piston rod by adjusting the input signal of the torque motor.

[0008] Further, an oil tank T is arranged in the micro pump. An oil inlet of the micro pump is connected with the oil tank T. An oil outlet of the oil tank T is connected with the hydraulic cylinder. An accumulator and a pressure sensor are arranged on the shell and are connected with the oil outlet of the micro pump. A pressure increasing screw plug is arranged at the end of the micro pump away from the brushless motor to adjust the pressure of the oil tank T.

[0009] Further, the torque motor comprises a connecting seat. An armature is arranged on the connecting seat. The armature is fixed with the connecting seat by a special-shaped spring arranged behind the armature. The armature is embedded with two groups of coil frames with control coils on the front and back sides of the armature. Two pole shoes are embedded on the upper and lower sides of the armature. Four magnetic steels are arranged between the two pole shoes.

[0010] Further, a sleeve ring is arranged on the side of the connecting seat away from the piston rod. A linear displacement sensor for detecting the displacement of the piston rod or for realizing closed-loop control of the position of the piston rod is arranged in the sleeve ring. The linear displacement sensor is used to position the displacement of the piston rod by displacement feedback, to give a feedback signal to the controller when the pump is controlled, and to control the stop, forward rotation pressure compensation, reverse pressure relief and commutation of the brushless motor.

[0011] Further, the piston rod is connected with the armature after being inserted into the piston sleeve and the connecting seat. Left and right concentric rings are arranged on the two ends of the piston rod and the piston sleeve. The right concentric ring is arranged on the end close to the torque motor.

[0012] Further, the piston rod is sequentially provided with a first convex ring, a second convex ring, a high-pressure oil guiding hole a2, a low-pressure oil guiding hole b2, a high-pressure groove a3 and a low-pressure groove b3 between the left concentric ring and the right concentric ring from left to right. The high-pressure oil guiding hole a2 is arranged on the piston rod between the left concentric ring and the first convex ring. The low-pressure oil guiding hole b2 is arranged at the connection between the second convex ring and the piston rod. The high-pressure groove a3 and the low-pressure groove b3 are arranged on the second convex ring. The high-pressure oil guiding hole a2 is in communication with the high-pressure groove a3. The low-pressure oil guiding hole b2 is in communication with the low-pressure groove b3. The high-pressure groove a3 and the low-pressure groove b3 are centrally and symmetrically distributed in pairs around the second convex ring. The working edges of the high-pressure groove a3 and the low-pressure groove b3 are both bevels or helical lines.

[0013] Further, the closed cavity between the piston sleeve, the left concentric ring and the first convex ring is a high-pressure cavity A, which is in communication with the oil outlet of the micro pump through a one-way valve. The closed cavity between the first convex ring, the piston sleeve and the second convex ring is a low-pressure cavity B, which is connected with the oil inlet of the micro pump. The closed cavity between the piston sleeve, the second convex ring and the right concentric ring is a control cavity C. The piston sleeve is sequentially provided with a high-pressure hole a1, a low-pressure hole b1 and a control groove c1 between the left concentric ring and the right concentric ring from left to right. The high-pressure hole a1 is in communication with the high-pressure cavity A. The low-pressure hole b1 is in communication with the low-pressure cavity B. The control groove c1 is in communication with the control cavity C. The high-pressure hole a1 and the low-pressure hole b1 are radially uniformly distributed hole channels. The control groove c1 is a pair of centrally and symmetrically distributed bevel grooves. The oil outlet of the micro pump 1 flows into the control cavity C through the one-way valve, the high-pressure hole a1, the high-pressure oil guiding hole a2, the high-pressure groove a3, and then returns to the oil tank T through the low-pressure groove b3, the low-pressure oil guiding hole b2, the low-pressure hole b1 and the low-pressure cavity B.

[0014] Further, the oil outlet of the micro pump is a high-pressure cavity pressure Ps, which is in communication with the high-pressure hole a1 of the piston sleeve, the high-pressure oil guiding hole a2 of the piston rod 312 and the high-pressure groove a3 of the piston rod. The oil inlet of the micro pump is a low-pressure cavity pressure Pt, which is in communication with the low-pressure hole b1 of the piston sleeve, the low-pressure oil guiding hole b2 of the piston rod and the low-pressure groove b3 of the piston rod. The control groove c1 of the piston sleeve is in communication with the control cavity C. A pair of high-pressure grooves a3 and low-pressure grooves b3 of the piston rod cooperate with the corresponding control groove c1 of the piston sleeve to form a hydraulic damping half-bridge.

[0015] Further, the motion law of the piston rod is determined by the bevel parameters of the high-pressure groove a3, the low-pressure groove b3 and the control groove c1. The control rotation angle of the piston rod is determined by the bevel parameters of the high-pressure groove a3, the low-pressure groove b3 and the control groove c1. θ The control rotation angle of the piston rod is provided by the armature of the torque motor. θThe piston rod displacement is linearly related to the displacement of the piston rod; and the high-pressure cavity A working area As on the high-pressure cavity side of the piston rod and the control cavity C working area Ac on the control cavity side are related in any balance position by the formula: Ps*As=Pc*Ac, wherein Ps is the high pressure of the high-pressure cavity A, and Pc is the control pressure of the control cavity C.

[0016] Further, the micro pump oil outlet is provided with a safety valve, the safety valve is a normally closed valve, and the safety valve is opened to release pressure to the oil tank T when the pressure exceeds the limit value; the micro pump is provided with an oil supplement port, the oil supplement port is communicated with the system through an oil supplement valve; and the shell is further provided with an exhaust port communicated with the micro pump, and the exhaust port is communicated with the system through an exhaust valve, so as to discharge the gas in each cavity during the first oiling process of the system.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] 1) The servo cylinder is integrated with the micro pump, the volume is reduced, the miniaturization is easier to realize, the functions of the servo valve and the hydraulic cylinder are considered at the same time, the response speed is fast, and the energy consumption is low; and the servo cylinder realizes mechanical feedback and electrical feedback double feedback, and can realize open-loop and closed-loop control;

[0019] 2) The present application can realize pump control mode, valve control mode or combination mode of pump control and valve control synchronization, can adapt to various working conditions, and has wide application range;

[0020] 3) The piston rod output displacement of the present application can realize stepless speed regulation, the control precision is high, and the power is large;

[0021] 4) The present application is modularly designed, the micro pump and the shell and the servo cylinder and the shell are all installed in a plug-in manner, the pipeline layout is reduced, and the production, assembly, maintenance, interchangeability and use are facilitated. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic view of the present application;

[0023] Figure 2 is an internal sectional view of the present application;

[0024] Figure 3 is a working principle diagram of the present application.

[0025] In the figure: 1 - micro pump, 2 - brushless motor, 3 - servo cylinder, 300 - pole shoe, 301 - magnetic steel, 302 - linear displacement sensor, 303 - collar, 304 - control coil, 305 - special-shaped spring, 306 - end cover, 307 - armature, 308 - coil skeleton, 309 - right concentric ring, 310 - connecting skeleton, 311 - piston sleeve, 312 - piston rod, 313 - left concentric ring, 4 - one-way valve, 5 - safety valve, 6 - exhaust port, 7 - exhaust valve, 8 - booster plug, 9 - shell, 10 - pressure sensor, 11 - accumulator, 12 - oil supplement valve, 13 - oil supplement port, 14 - first convex ring, 15 - second convex ring, A - high pressure cavity, B - low pressure cavity, C - control cavity, T - oil tank, As - high pressure cavity working area, Ac - control cavity working area, Ps - high pressure cavity pressure, Pt - low pressure cavity pressure, Pc - control cavity pressure, al - high pressure hole, a2 - high pressure oil inlet hole, a3 - high pressure groove, bl - low pressure hole, b2 - low pressure oil inlet hole, b3 - low pressure groove, cl - control groove. Embodiment

[0026] A micro electro-hydraulic actuator is further described below in combination with the accompanying drawings.

[0027] As Figures 1-3 shown, a micro electro-hydraulic actuator includes a shell 9, a micro pump 1 is fitted and inserted on the upper part of the shell 9, and a servo cylinder 3 is fitted and inserted on the lower part of the shell 9. The servo cylinder 3 includes a hydraulic cylinder and a torque motor. The hydraulic cylinder is inserted into the shell 9 and includes a piston sleeve 311 inserted into the shell 9 in steps and a piston rod 312 inserted into the piston sleeve 311. The torque motor is arranged on one side of the hydraulic cylinder and is connected with the piston rod 312. A brushless motor 2 is arranged above the torque motor and is connected with the micro pump 1 inserted into the shell 9. The micro pump 1 and the hydraulic cylinder are connected in the shell 9. The brushless motor 2 and the servo cylinder 3 are respectively connected with a controller. The controller is used to adjust the rotation speed of the brushless motor 2 to adjust the outlet flow of the micro pump, and to adjust the rotation angle of the armature 307 in the torque motor to control the displacement of the servo cylinder 3, so as to realize the displacement adjustment of the piston rod 312 of the hydraulic cylinder by driving the micro pump 1 by the brushless motor 2 and / or the displacement adjustment of the piston rod 312 by adjusting the input signal of the torque motor.

[0028] Specifically, the micro pump 1 is provided with an oil tank T, the oil inlet of the micro pump 1 is communicated with the oil tank T, and the oil outlet of the oil tank T is communicated with the hydraulic cylinder through a one-way valve 4. The brushless motor 2 drives the micro pump 1, the oil outlet of the micro pump 1 flows into the servo cylinder 3 through the one-way valve 4, and finally circulates to the oil tank T from the servo cylinder 3. The oil outlet of the micro pump 1 is also connected to a safety valve 5, which protects the safety of the actuator system. When the pressure exceeds the limit value, the safety valve 5 opens to release pressure to the oil tank T. The safety valve 5 is a normally closed valve port, which opens to release pressure when the system pressure exceeds the set pressure of the safety valve 5, thereby protecting the system from excessive pressure and reducing the pressure transient impact. The housing 9 is provided with an accumulator 11 and a pressure sensor 10 connected to the oil outlet of the micro pump 1. The accumulator 11 provides a holding pressure for the actuator and reduces pressure pulsation. The pressure sensor 10 monitors the outlet pressure of the micro pump 1. The micro pump 1 is provided with a replenishment port 13, which is communicated with the system through a replenishment valve 12 for the first oil filling or oil replenishment during use. The replenishment valve 12 is a one-way valve, and the medium can only enter the system from the outside, and cannot flow in the opposite direction to avoid leakage. The housing 9 is also provided with an exhaust port 6 communicated with the micro pump 1, which is communicated with the system through an exhaust valve 7 for the exhaust of gas in the cavities during the first oil filling. The exhaust valve 7 is a normally closed hand-operated one-way valve, which is used for exhaust during the first oil filling, and is locked after the exhaust is completed, so that the system is not connected to the outside to avoid leakage. The end of the micro pump 1 away from the brushless motor 2 is provided with a pressure-increasing screw plug 8 for adjusting the pressure of the oil tank T of the micro pump 1. By changing the inlet pressure of the micro pump 1, the problem of air suction at high speed is prevented.

[0029] The torque motor comprises a connecting seat 310, an armature 307 is arranged on the connecting seat 310, the armature 307 is fixed with the connecting seat 310 through a special-shaped spring 305 arranged behind the armature 307, and one side of the special-shaped spring 305 is screw-connected with the connecting seat 310; an end cover 306 is arranged on the outer cover of the connecting seat 310, and the end cover 306 is fixed with the connecting seat 310 through a screw or the like fastener. Specifically, the armature 307 is embedded with two groups of coil frames 308 wound with control coils 304 on the front and back sides of the armature 307, two pole pieces 300 are embedded on the upper and lower sides of the armature 307, four magnetic steels 301 are arranged between the two pole pieces 300, a sleeve ring 303 is arranged on the side of the connecting seat 310 away from a piston rod 312, the sleeve ring 303 is connected with the connecting seat 310, and a linear displacement sensor 302 is arranged in the sleeve ring 303, which is used for detecting the displacement of the piston rod 312 or realizing closed-loop control on the position of the piston rod 312. The linear displacement sensor 302 precisely positions the displacement of the piston rod 312 in the servo cylinder 3 through displacement feedback, and simultaneously feeds back a signal to a controller during pump control, so as to control the brushless motor 2 to stop, positively rotate to supplement pressure, reversely rotate to release pressure, and change direction. In the embodiment, the four magnetic steels 301 are installed with consistent magnetic pole directions.

[0030] The piston rod 312 is connected with the armature 307 after penetrating the piston sleeve 311 and the connecting seat 310, and the piston rod 312 is connected with the armature 307 through a pin. The two ends of the piston rod 312 sleeved with the piston sleeve 311 are respectively provided with a left concentric ring 313 and a right concentric ring 309, and the right concentric ring 309 is arranged at one end close to the torque motor. The piston rod 312 is sequentially provided with a first convex ring 14, a second convex ring 15, a high-pressure oil guiding hole a2, a low-pressure oil guiding hole b2, a high-pressure groove a3 and a low-pressure groove b3 between the left concentric ring 313 and the right concentric ring 309. The high-pressure oil guiding hole a2 is arranged on the piston rod 312 between the left concentric ring 313 and the first convex ring 14, the low-pressure oil guiding hole b2 is arranged at the connection position of the second convex ring 15 and the piston rod 312, and the high-pressure groove a3 and the low-pressure groove b3 are arranged on the second convex ring 15. The high-pressure oil guiding hole a2 is in communication with the high-pressure groove a3, the low-pressure oil guiding hole b2 is in communication with the low-pressure groove b3, the high-pressure groove a3 and the low-pressure groove b3 are distributed in a pair of central symmetry around the second convex ring 15, and the working edges of the high-pressure groove a3 and the low-pressure groove b3 are both bevels or helical lines. The closed cavity between the piston sleeve 311, the left concentric ring 313 and the first convex ring 14 is a high-pressure cavity A, the high-pressure cavity A is in communication with the oil outlet of the micro pump 1 through a one-way valve 4; the closed cavity between the first convex ring 14, the piston sleeve 311 and the second convex ring 15 is a low-pressure cavity B, and the low-pressure cavity B is in communication with the oil inlet of the micro pump 1; and the closed cavity between the piston sleeve 311, the second convex ring 15 and the right concentric ring 309 is a control cavity C. The piston sleeve 311 is sequentially provided with a high-pressure hole a1, a low-pressure hole b1 and a control groove c1 between the left concentric ring 313 and the right concentric ring 309. The high-pressure hole a1 is in communication with the high-pressure cavity A, the low-pressure hole b1 is in communication with the low-pressure cavity B, and the control groove c1 is in communication with the control cavity C. The high-pressure hole a1 and the low-pressure hole b1 are radial uniformly distributed hole channels, and the control groove c1 is a pair of central symmetrically distributed bevel grooves. The oil outlet of the micro pump 1 is the high-pressure cavity pressure Ps, which is communicated through the high-pressure hole a1 of the piston sleeve 311, the high-pressure oil guiding hole a2 of the piston rod 312 and the high-pressure groove a3 of the piston rod 312; the oil inlet of the micro pump 1 is the low-pressure cavity pressure Pt, which is communicated through the low-pressure hole b1 of the piston sleeve 113, the low-pressure oil guiding hole b2 of the piston rod 312 and the low-pressure groove b3 of the piston rod 312; the control groove c1 of the piston sleeve 311 is in communication with the control cavity C, and the pair of high-pressure grooves a3 and low-pressure grooves b3 of the piston rod 312 and the corresponding control groove c1 of the piston sleeve 311 are used in cooperation to form a hydraulic damping half-bridge. In order to prolong the service life of the hydraulic cylinder, the left concentric ring 313 and the right concentric ring 309 are both made of wear-resistant materials.

[0031] It can be understood that the oil outlet of the micro pump 1 flows into the control cavity C through the one-way valve 4, the high-pressure hole a1, the high-pressure oil guide a2 and the high-pressure groove a3, and flows back to the low-pressure cavity B through the low-pressure groove b3, the low-pressure oil guide hole b2, the low-pressure hole b1 and the oil tank T. By energizing the control coil 304, the driving armature 307 drives the piston rod 312 to rotate in the piston sleeve 311, and the axial movement of the piston rod 312 is realized by the change of the control pressure Pc generated by the movement of the piston rod 312, and the closed-loop control of the servo cylinder 3 is realized by the feedback displacement of the linear displacement sensor 302.

[0032] The piston rod 312 can rotate freely and move axially in the piston sleeve 311, and the piston rod 312 and the piston sleeve 311 cooperate to adopt a servo screw mechanism, which can convert rotary motion into axial movement; the piston rod 312 has a valve core structure, and simultaneously considers the axial thrust of the hydraulic cylinder. The movement law of the piston rod 312 is determined by the slope parameters of the high-pressure groove a3, the low-pressure groove b3 and the control groove c1, and the control torque of the piston rod 312, i.e. the control angle θ is provided by the armature 307 of the torque motor, and the control angle θ has a linear relationship with the displacement of the piston rod 312, which is convenient for control. The working area As of the high-pressure cavity A on the high-pressure cavity side of the piston rod 312 and the working area Ac of the control cavity C on the control cavity side have the following relationship formula at any balance position: Ps*As=Pc*Ac, wherein Ps is the high pressure of the high-pressure cavity A, and Pc is the control pressure of the control cavity C.

[0033] In order to increase the service life of the servo cylinder, the left and right concentric rings 313 and 309 are made of wear-resistant materials. In order to ensure the sealing performance of the entire servo cylinder, a sealing ring is arranged at the stepped connection between the piston sleeve 311 and the shell 9, a sealing ring is arranged between the piston sleeve 311 and the connecting seat 310 to prevent internal leakage, a sealing ring is arranged between the shell 9 and the piston rod 312, a sealing ring is arranged on the matching surface of the connecting seat 310 and the coil skeleton 308, a sealing ring is arranged between the connecting seat 310 and the shell 9, and a sealing ring is arranged between the connecting seat 310 and the sleeve ring 303 to prevent external leakage.

[0034] The actuator of the application includes three working modes: pump control mode, valve control mode and combined mode. The pump control mode is to adjust only the displacement of the piston rod 312 by adjusting the brushless motor 2 (at this time the torque motor inputs a constant square wave signal); the valve control mode is to adjust only the displacement of the piston rod 312 by adjusting the input signal of the torque motor (at this time the brushless motor inputs a constant signal, i.e. a constant rotating speed); and the combined mode is to adjust the displacement of the piston rod 312 by adjusting the rotating speed of the brushless motor and the rotating angle of the torque motor at the same time.

[0035] Specifically, the pump control mode: the controller gives the brushless motor 2 signal according to the actual working condition to control its speed, at the same time, when the controller gives the control coil 304 of the servo cylinder 3 positive constant step current signal, the torque motor generates excitation magnetic flux, the armature 307 generates differential torque under the action of differential magnetic flux, drives the piston rod 312 to rotate synchronously in the positive direction, at this time, the high pressure groove a3 and the control groove c1 overlap area increases, the low pressure groove b3 and the control groove c1 overlap area decreases, the control pressure Pc increases, the effective thrust of the control pressure Pc on the piston rod 312 increases, the piston rod 312 moves in the positive direction, until the high pressure groove a3 and the low pressure groove b3 and the control groove c1 overlap area is the same again, the control pressure Pc decreases to the initial value, the effective thrust of the control pressure Pc on the piston rod 312 and the effective thrust of the high pressure cavity pressure Ps on the piston rod 312 are equal again, the piston rod 312 is balanced at the balance position and is stationary. Conversely, when the controller gives the control coil 304 of the servo cylinder 3 reverse constant step current signal, the piston rod 312 moves in the reverse direction to the force balance position. Wherein, the angle of the armature 307 controls the displacement of the piston rod 312, the speed of the micro pump 1 controls the extension and retraction speed of the piston rod 312; the linear displacement sensor 302 detects the displacement of the piston rod 312 and gives the controller feedback signal, when the piston rod 312 reaches the specified position, the brushless motor stops rotating, and the system pressure is maintained; when the system pressure decreases, the motor works again to supplement the system pressure.

[0036] It can be understood that the system realizes the control of the speed and fixed position of the piston rod 312 by adjusting the speed of the brushless motor 2 and the fixed angle of the armature 307, and the intermittent work greatly reduces the energy consumption.

[0037] Valve control mode: the controller gives the brushless motor 2 a constant step signal to control its fixed speed according to the actual working condition. When the controller gives the control coil 304 of the servo cylinder 3 a following current signal (which can be a triangular wave, a sine wave or other continuous waveforms), the torque motor generates excitation magnetic flux, the armature 307 generates differential torque under the action of differential magnetic flux, and the piston rod 312 is driven to rotate synchronously in the positive direction. At this time, the overlap area of the high-pressure groove a3 and the control groove c1 increases, the overlap area of the low-pressure groove b3 and the control groove c1 decreases, the control pressure Pc increases, the effective thrust of the control pressure Pc on the piston rod 312 increases, the piston rod 312 moves in the positive axial direction, and the piston rod 312 is in a force balance position and is stationary until the overlap areas of the high-pressure groove a3 and the low-pressure groove b3 and the control groove c1 are the same again, the control pressure Pc decreases to the initial value, and the effective thrust of the control pressure Pc on the piston rod 312 and the effective thrust of the high-pressure cavity pressure Ps on the piston rod 312 are equal again. The piston rod 312 moves in the reverse axial direction to the force balance position when the controller gives the control coil 304 of the servo cylinder 3 a constant step current signal in the reverse direction. The piston rod 312 makes a following action consistent with the input signal, and can also stop at a certain position or directly reach a certain position according to actual working requirements. At this time, the rotation angle and rotation speed of the armature 307 control the displacement amount and extension and retraction speed of the piston rod 312. The linear displacement sensor 302 feeds back a signal to the controller for closed-loop control of the piston rod, thereby improving the response speed and control accuracy of the system.

[0038] It can be understood that the system realizes rapid and accurate control of the speed and position of the piston rod 312 by adjusting the fixed speed of the brushless motor 2 and the stepless adjustment of the rotation angle of the armature 307, stepless displacement adjustment, fast response speed and higher closed-loop control accuracy.

[0039] Combined mode: the controller inputs signals to the brushless motor 1 and the control coil 304 of the torque motor, and simultaneously couples the micro pump 1 and the servo cylinder 3, so that any one of the above pump control mode or valve control mode can be realized, and the intersection of the two modes can also be coupled.

[0040] It can be understood that the system can realize separate control or coupled control, has high control accuracy, fast response speed, wide adjustment range, can reduce energy consumption to the greatest extent and output the required power according to the working condition, is more flexible to use, and has a wider range of applications.

[0041] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A miniature electro-hydraulic actuator, characterized in that, The system includes a housing (9), with a micro pump (1) inserted into the upper part of the housing (9) and a servo cylinder (3) inserted into the lower part of the housing (9). The servo cylinder (3) includes a hydraulic cylinder and a torque motor. The hydraulic cylinder is inserted into the housing (9) and includes a stepped piston sleeve (311) inserted into the housing (9) and a piston rod (312) inserted into the piston sleeve (311). The torque motor is located on one side of the hydraulic cylinder and is connected to the piston rod (312). A brushless motor (2) is located above the torque motor. The brushless motor (2) is connected to the micro pump (1) inserted into the housing (9). 1) The micro pump (1) inside the housing (9) is connected to the hydraulic cylinder; the brushless motor (2) and the servo cylinder (3) are respectively connected to the controller. The controller adjusts the speed of the brushless motor (2) to adjust the outlet flow of the micro pump (1), and adjusts the angle of the armature (307) of the torque motor to control the displacement of the servo cylinder (3), so as to realize the operation of the micro pump (1) driven by the brushless motor (2) to adjust the displacement of the piston rod (312) of the hydraulic cylinder and / or adjust the displacement of the piston rod (312) by adjusting the signal of the input torque motor.

2. The miniature electro-hydraulic actuator according to claim 1, characterized in that, The micro pump (1) is equipped with an oil tank T. The oil inlet of the micro pump (1) is connected to the oil tank T, and the oil outlet of the oil tank T is connected to the hydraulic cylinder. An accumulator (11) and a pressure sensor (10) connected to the oil outlet of the micro pump (1) are provided on the housing (9). A pressure boosting plug (8) is provided at the end of the micro pump (1) away from the brushless motor (2) to adjust the pressure of the oil tank T of the micro pump (1).

3. A miniature electro-hydraulic actuator according to claim 2, characterized in that, The torque motor includes a connecting seat (310), on which an armature (307) is provided. The armature (307) is fixed to the connecting seat (310) by a shaped spring (305) provided thereafter. Two sets of coil frames (308) with control coils (304) are embedded on the front and rear sides of the armature (307). Two pole shoes (300) are embedded on the upper and lower sides of the armature (307), and four magnets (301) are provided between the two pole shoes (300).

4. A miniature electro-hydraulic actuator according to claim 3, characterized in that, The connecting seat (310) is provided with a collar (303) on the side away from the piston rod (312). The collar (303) is provided with a linear displacement sensor (302) for detecting the displacement of the piston rod (312) or realizing closed-loop control of the position of the piston rod (312). The linear displacement sensor (302) locates the displacement of the piston rod (312) through displacement feedback, and provides feedback signals to the controller during pump control to control the stop, forward pressure replenishment, reverse pressure relief and reversing operation of the brushless motor (2).

5. A miniature electro-hydraulic actuator according to claim 4, characterized in that, The piston rod (312) passes through the piston sleeve (311) and the connecting seat (310) and then connects with the armature (307); the two ends of the piston rod (312) that are sleeved with the piston sleeve (311) are respectively provided with a left concentric ring (313) and a right concentric ring (309), and the right concentric ring (309) is provided at the end closer to the torque motor.

6. A miniature electro-hydraulic actuator according to claim 5, characterized in that, The piston rod (312) is provided with a first convex ring (14), a second convex ring (15), a high-pressure oil inlet a2, a low-pressure oil inlet b2, a high-pressure groove a3, and a low-pressure groove b3 in sequence from the left concentric ring (313) to the right concentric ring (309). The high-pressure oil inlet a2 is located on the piston rod (312) between the left concentric ring (313) and the first convex ring (14). The low-pressure oil inlet b2 is located at the connection between the second convex ring (15) and the piston rod (312). The high-pressure groove a3 and the low-pressure groove b3 are located on the second convex ring (15). The high-pressure oil inlet a2 is connected to the high-pressure groove a3, and the low-pressure oil inlet b2 is connected to the low-pressure groove b3. The high-pressure groove a3 and the low-pressure groove b3 are symmetrically distributed in pairs around the second convex ring (15). The working sides of the high-pressure groove a3 and the low-pressure groove b3 are both inclined sides or spiral lines.

7. A miniature electro-hydraulic actuator according to claim 6, characterized in that, The closed cavity between the piston sleeve (311), the left concentric ring (313), and the first convex ring (14) is a high-pressure cavity A, which is connected to the oil outlet of the micro pump (1) through a one-way valve (4); the closed cavity between the first convex ring (14), the piston sleeve (311), and the second convex ring (15) is a low-pressure cavity B, which is connected to the oil inlet of the micro pump (1); the closed cavity between the piston sleeve (311), the second convex ring (15), and the right concentric ring (309) is a control cavity C; and the piston sleeve (311) is connected to the left concentric ring (313) Between the right concentric ring (309) and the left concentric ring (309), there are high pressure hole a1, low pressure hole b1 and control groove c1 in sequence. High pressure hole a1 is connected to high pressure chamber A, low pressure hole b1 is connected to low pressure chamber B, and control groove c1 is connected to control chamber C. High pressure hole a1 and low pressure hole b1 are radially uniformly distributed channels, and control groove c1 is a pair of centrally symmetrically distributed inclined grooves. The oil outlet of the micro pump (1) flows into control chamber C through the one-way valve (4), high pressure hole a1, high pressure oil inlet a2 and high pressure groove a3, and flows back to low pressure chamber B through low pressure groove b3, low pressure oil inlet hole b2 and low pressure hole b1 and then returns to the oil tank T.

8. A miniature electro-hydraulic actuator according to claim 1, characterized in that, The outlet of the micro pump (1) is the high-pressure chamber pressure Ps, which is connected to the high-pressure groove a3 of the piston rod (312) through the high-pressure hole a1 of the piston sleeve (311), the high-pressure oil inlet a2 of the piston rod (312); the inlet of the micro pump (1) is the low-pressure chamber pressure Pt, which is connected to the low-pressure groove b3 of the piston rod (312) through the low-pressure hole b1 of the piston sleeve (311), the low-pressure oil inlet b2 of the piston rod (312); the control groove c1 of the piston sleeve (311) is connected to the control chamber C, and the pair of high-pressure grooves a3 and low-pressure grooves b3 of the piston rod (312) and the corresponding control groove c1 of the piston sleeve (311) cooperate to form a hydraulic damping half bridge.

9. A miniature electro-hydraulic actuator according to claim 8, characterized in that, The motion law of the piston rod (312) is determined by the hypotenuse parameters of the high-pressure groove a3, the low-pressure groove b3, and the control groove c1, and the control angle of the piston rod (312) is... θ The torque motor armature (307) provides the control of the rotation angle. θ The displacement of the piston rod (312) is linearly related; and the working area As of the high pressure chamber A on the high pressure chamber side of the piston rod (312) and the working area Ac of the control chamber C on the control chamber side are related at any equilibrium position as: Ps*As=Pc*Ac, where Ps is the high pressure of the high pressure chamber A and Pc is the control pressure of the control chamber C.

10. A miniature electro-hydraulic actuator according to any one of claims 2-9, characterized in that, The micro pump (1) is also equipped with a safety valve (5) at its oil outlet. The safety valve (5) is a normally closed valve. When the pressure exceeds its limit value, the safety valve (5) opens to release pressure to the oil tank T. The micro pump (1) is equipped with an oil replenishment port (13), which is connected to the system via an oil replenishment valve (12). The housing (9) is also equipped with an exhaust port (6) connected to the micro pump (1). The exhaust port (6) is connected to the system via an exhaust valve (7) to discharge the gas in each chamber during the first refueling process of the system.

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