A miniature electro-hydraulic servo cylinder

Abstract

The present invention discloses a miniature electro-hydraulic servo cylinder, comprising a hydraulic cylinder assembly and a torque motor assembly that are connected in a coordinated manner. The hydraulic cylinder assembly includes a cylinder body, in which a piston rod is movably mounted; the torque motor assembly includes a connecting seat that is connected in a coordinated manner with the cylinder body, an armature is provided on the connecting seat, and the armature is fixed to the connecting seat by a special-shaped spring provided thereon, and control coils are provided on both sides of the armature; the piston rod is matched with the cylinder body and the connecting seat through a piston sleeve provided thereon, and the piston rod is connected to the armature after passing through the cylinder body and the connecting seat. The armature is driven by the power supply of the control coil to drive the piston rod to rotate in the piston sleeve, and the change of the control pressure Pc generated when the piston rod moves realizes the axial movement of the piston rod. The closed-loop control of the servo cylinder is realized by feedback of the displacement through a linear displacement sensor. The present application is an integrated design of a valve group and a hydraulic cylinder, which is conducive to achieving miniaturization and a high power-to-weight ratio; the piston rod is directly driven by the torque motor, and the response speed is fast.

Description

Technical Field

[0001] The invention belongs to the technical field of servo cylinders, and in particular relates to a micro-sized electro-hydraulic servo cylinder. Background Art

[0002] As a key technology of hydraulic drive, electro-hydraulic servo technology is required to have the characteristics of fast response, high precision, strong anti-pollution ability, adaptability to inertial loads and long working life. As the power actuator in the hydraulic servo system, the electro-hydraulic servo cylinder is required to have low friction, good resistance to lateral loads and high-speed movement.

[0003] Compared to electric servo cylinders, electro-hydraulic servo cylinders offer a higher power-to-weight ratio; they can achieve push-pull forces and stepless speed regulation over a wide speed range; they are responsive and stable, effectively buffering external load impacts and providing high stroke control precision. Current electro-hydraulic servo cylinders typically consist of a valve assembly, piston rod, and cylinder body. The valve assembly throttling results in significant energy loss and is limited in size, preventing miniaturization. Summary of the Invention

[0004] In order to make up for the shortcomings of the prior art, the present invention provides a miniature electro-hydraulic servo cylinder, comprising a hydraulic cylinder assembly and a torque motor assembly that are matched and connected together. The hydraulic cylinder assembly includes a cylinder body, and a piston rod is movably sleeved in the cylinder body; the torque motor assembly includes a connecting seat that is matched and connected to the cylinder body, and an armature is provided on the connecting seat. The armature is fixed to the connecting seat by a special-shaped spring arranged thereafter, and a control coil is provided on both sides of the armature; the piston rod is fixed to the cylinder body and the connecting seat by a piston sleeve sleeved thereon, and the piston rod is matched and connected to the armature after passing through the cylinder body and the connecting seat. The control coil is energized and turned on, driving the armature to drive the piston rod to rotate in the piston sleeve, and the change of the control pressure Pc generated when the piston rod moves realizes the axial movement of the piston rod, and the closed-loop control of the servo cylinder is realized by feedback of the displacement by a linear displacement sensor arranged in the connecting seat.

[0005] Furthermore, a left concentric ring and a right concentric ring are respectively provided at the two ends where the piston rod and the piston sleeve are sleeved, and the right concentric ring is provided at an end close to the armature.

[0006] Furthermore, the piston rod is provided with a first convex ring, a second convex ring, a high-pressure oil inlet hole a2, a low-pressure oil inlet hole b2, a high-pressure groove a3, and a low-pressure groove b3 in sequence from the left concentric ring to the right concentric ring. The high-pressure oil inlet hole a2 is provided on the piston rod between the left concentric ring and the first convex ring; the low-pressure oil inlet hole b2 is provided at the connection between the second convex ring and the piston rod; the high-pressure groove a3 and the low-pressure groove b3 are provided on the second convex ring; and the high-pressure oil inlet hole a2 is connected to the high-pressure groove a3, and the low-pressure oil inlet hole 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 center of the second convex ring, and the working edges of the high-pressure groove a3 and the low-pressure groove b3 are hypotenuses.

[0007] Furthermore, the piston sleeve is stepped into the cylinder body, and the closed cavity formed between the piston sleeve, the left concentric ring and the first convex ring is the high-pressure cavity A; the closed cavity formed between the first convex ring, the piston sleeve and the second convex ring is the low-pressure cavity B; the closed cavity between the piston sleeve, the second convex ring and the right concentric ring is the control cavity C.

[0008] Furthermore, the piston sleeve is provided with a high-pressure hole a1, a low-pressure hole b1, and a control groove c1 in sequence from the left concentric ring to the right concentric ring. The high-pressure hole a1 is connected to the high-pressure chamber A, the low-pressure hole b1 is connected to the low-pressure chamber B, and the control groove c1 is connected to the control chamber C; the high-pressure hole a1 and the low-pressure hole b1 are radially uniformly distributed channels, and the control groove c1 is a pair of centrally symmetrically distributed inclined grooves; the high-pressure port P of the cylinder body is connected to the high-pressure groove a3 of the piston rod through the high-pressure hole a1 of the piston sleeve and the high-pressure oil inlet hole a2 of the piston rod; the low-pressure port Q of the cylinder body is connected to the low-pressure groove b3 of the piston rod through the low-pressure hole b1 of the piston sleeve and the low-pressure oil inlet hole b2 of the piston rod; the high-pressure groove a3, the low-pressure groove b3 of the piston rod and the corresponding control groove c1 of the piston sleeve are used in conjunction to form a hydraulic damping half-bridge.

[0009] Furthermore, the working area As of the high-pressure chamber A on the high-pressure chamber side of the piston rod and the working area Ac of the control chamber C on the control chamber side are related by the formula Ps*As=Pc*Ac at any equilibrium position, where Ps is the high pressure of the high-pressure chamber A and Pc is the control pressure of the control chamber C.

[0010] Furthermore, the left concentric ring and the right concentric ring are both made of wear-resistant materials.

[0011] Furthermore, the piston rod is connected to the armature via a pin; the outer cover of the connecting seat is provided with an end cover, and the end cover is fixed to the connecting seat via screws.

[0012] Furthermore, two groups of coil frames with control coils are embedded in the front and rear sides of the armature, two pole shoes are embedded in the upper and lower sides of the armature, four magnets are provided between the two pole shoes, and a ring is provided on the side of the armature away from the cylinder body, the ring is cooperated with the connecting seat, and a linear displacement sensor cooperated with the armature is provided in the ring, and the displacement of the armature is detected by the linear displacement sensor to perform closed-loop control.

[0013] Furthermore, a sealing ring is provided between the piston sleeve and the cylinder body step, and a sealing ring is provided between the piston sleeve and the connecting seat to prevent internal leakage of the servo cylinder; a sealing ring is provided between the cylinder body and the piston rod, a sealing ring is provided on the mating surface of the connecting seat and the coil frame, a sealing ring is provided between the connecting seat and the cylinder body, and a sealing ring is provided between the connecting seat and the ring to prevent external leakage of the servo cylinder.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] (1) This application is an integrated design of the valve group and the hydraulic cylinder, which greatly simplifies the structure and reduces the volume, which is conducive to miniaturization and high power-to-weight ratio;

[0016] (2) The piston rod of the present application is in a suspended state, with fewer friction pairs, which greatly reduces the negative impact of static friction;

[0017] (3) The torque motor of the present application directly drives the piston rod without any intermediate links, has a fast response speed, and is easy to implement proportional servo control;

[0018] (4) The present application can realize stepless speed regulation, high control accuracy and large hydraulic driving force; and the piston rod of the servo cylinder is linearly related to the input signal. When the input signal is a square wave, a triangle wave, a sine wave, etc., the output displacement of the piston rod is consistent with the input signal waveform, which can realize open-loop and closed-loop continuous control, improve control accuracy and dynamic response speed, and meet the needs of various working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 It is the internal structure diagram of the present invention;

[0021] Figure 3 is a cross-sectional view of the present invention;

[0022] Figure 4 Schematic diagram of the structure of the torque motor of the present invention;

[0023] Figure 5 It is a working schematic diagram of the present invention.

[0024] In the figure: 1-cylinder body, 2-left concentric ring, 3-piston sleeve, 4-piston rod, 5-right concentric ring, 6-connecting seat, 7-control coil, 8-magnet, 9-armature, 10-coil skeleton, 11-special-shaped spring, 12-collar, 13-linear displacement sensor, 14-pole shoe, 15-end cover, 16-first convex ring, 17-second convex ring, A-high-pressure chamber, B-low-pressure chamber, C-control chamber, As-high-pressure chamber working area, Ac-control chamber working area, P-high-pressure port, Q-low-pressure port, Ps-high pressure, Pc-control pressure, a1-high-pressure hole, a2-high-pressure oil guide hole, a3-high-pressure groove, b1-low-pressure hole, b2-low-pressure oil guide hole, a3-low-pressure groove, c1-control groove. DETAILED DESCRIPTION

[0025] The following is a further description of a miniature electro-hydraulic servo cylinder of the present invention with reference to the accompanying drawings.

[0026] like Figure 1-5 As shown, a miniature electro-hydraulic servo cylinder includes a hydraulic cylinder assembly and a torque motor assembly. The hydraulic cylinder assembly and the torque motor assembly are threadedly connected. The torque motor assembly includes a connecting seat 6 connected to the hydraulic cylinder assembly. An armature 9 is provided on the connecting seat 6. The armature 9 is fixed to the connecting seat 6 by a shaped spring 11 provided thereon. One side of the shaped spring 11 is screwed to the connecting seat 6. An end cap 15 is provided on the outer cover of the connecting seat 6. The end cap 15 is fixed to the connecting seat 6 by fasteners such as screws. The hydraulic cylinder assembly includes a cylinder body 1. A piston rod 4 is movably mounted within the cylinder body 1. The piston rod 4 passes through the cylinder body 1 and the connecting seat 6 and is connected to the armature 9. The piston rod 4 and the armature 9 are connected by a pin. The piston rod 4 is fixed to the cylinder body 1 and the connecting seat 6 by a piston sleeve 3 provided thereon. A left concentric ring 2 and a right concentric ring 5 are provided at the ends of the piston rod 4 and the piston sleeve 3, respectively. The right concentric ring 5 is provided at the end closest to the torque motor assembly. On the piston rod 4, a first convex ring 16, a second convex ring 17, a high-pressure oil inlet hole a2, a low-pressure oil inlet hole b2, a high-pressure groove a3, and a low-pressure groove b3 are sequentially provided between the left concentric ring 2 and the right concentric ring 5. The high-pressure oil inlet hole a2 is provided on the piston rod 4 between the left concentric ring 2 and the first convex ring 16, the low-pressure oil inlet hole b2 is provided at the connection between the second convex ring 17 and the piston rod 4, and the high-pressure groove a3 and the low-pressure groove b3 are provided on the second convex ring 17; and the high-pressure oil inlet hole a2 is connected to the high-pressure groove a3, and the low-pressure oil inlet hole 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 center of the second convex ring 17, and the working edges of the high-pressure groove a3 and the low-pressure groove b3 are oblique edges, that is, the high-pressure groove a3 and the low-pressure groove b3 are oblique grooves.

[0027] Specifically, two groups of coil frames 10 with control coils 7 are embedded on the front and rear sides of the armature 9, two pole shoes 14 are embedded on the upper and lower sides of the armature 9, four magnets 8 are arranged between the two pole shoes 14, and a ring 12 is provided on the side of the armature 9 away from the cylinder body 1. The ring 12 is connected to the connecting seat 6, and a linear displacement sensor 13 connected to the armature 9 is provided in the ring 12, which is used to detect the displacement or position of the armature 9 to achieve closed-loop control.

[0028] Furthermore, the piston sleeve 3 is inserted into the cylinder body 1 in a stepped manner. The enclosed chamber between the piston sleeve 3, the left concentric ring 2, and the first raised ring 16 is the high-pressure chamber A; the enclosed chamber between the first raised ring 16, the piston sleeve 3, and the second raised ring 17 is the low-pressure chamber B; and the enclosed chamber between the piston sleeve 3, the second raised ring 17, and the right concentric ring 5 is the control chamber C. The piston sleeve 3 is provided with a high-pressure hole a1, a low-pressure hole b1, and a control groove c1, sequentially from the left concentric ring 2 to the right concentric ring 5. The high-pressure hole a1 communicates with the high-pressure chamber A, the low-pressure hole b1 communicates with the low-pressure chamber B, and the control groove c1 communicates with the control chamber C. The high-pressure holes a1 and the low-pressure holes b1 are radially evenly distributed channels, while the control groove c1 is a pair of centrally symmetrically distributed oblique grooves. The high-pressure port P of the cylinder body 1 is connected to the high-pressure groove a3 of the piston rod through the high-pressure hole a1 of the piston sleeve 3 and the high-pressure oil inlet hole a2 of the piston rod 4; the low-pressure port Q of the cylinder body 1 is connected to the low-pressure groove b3 of the piston rod through the low-pressure hole b1 of the piston sleeve 3 and the low-pressure oil inlet hole b2 of the piston rod 4; the control groove c1 of the piston sleeve 3 is connected to the control chamber C, and a pair of high-pressure grooves a3 and low-pressure grooves b3 of the piston rod 4 and the corresponding control groove c1 of the piston sleeve 3 are used together to form a hydraulic damping half-bridge.

[0029] It can be understood that by energizing the control coil 7, the armature 9 is driven to drive the piston rod 4 to rotate in the piston sleeve 3, and the change in the control pressure Pc generated when the piston rod 4 moves realizes the axial movement of the piston rod 4, and the closed-loop control of the servo cylinder is realized by feedback of the displacement by the linear displacement sensor 13.

[0030] like Figure 5 As shown, the piston rod 4 can rotate and move axially freely in the piston sleeve 3. The movement law of the piston rod 4 is determined by the hypotenuse parameters of the high-pressure groove a3, the low-pressure groove b3, and the control groove c1. The piston rod 4 controls the torque, that is, the angle of rotation. θ Provided by the armature 9 of the torque motor, the angle is controlled θ The relationship between the working area As of the high-pressure chamber A on the high-pressure side of the piston rod 4 and the working area Ac of the control chamber C on the control chamber side is linear, making it easy to control. At any equilibrium position, the relationship between the working area As of the high-pressure chamber A on the high-pressure side of the piston rod 4 and the working area Ac of the control chamber C on the control chamber side is: 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.

[0031] In this embodiment, to extend the service life of the servo cylinder, both the left concentric ring 2 and the right concentric ring 5 are made of wear-resistant materials. To ensure the sealing performance of the entire servo cylinder, a sealing ring is provided between the piston sleeve 3 and the cylinder body 1, and between the piston sleeve 3 and the connecting seat 6 to prevent internal leakage. A sealing ring is provided between the cylinder body 1 and the piston rod 4, a sealing ring is provided on the mating surface of the connecting seat 6 and the coil bobbin 10, a sealing ring is provided between the connecting seat 6 and the cylinder body 1, and a sealing ring is provided between the connecting seat 6 and the collar 12 to prevent external leakage.

[0032] The specific working principle is: when the high-pressure port P is pressurized and the control coil 7 is not energized, the torque motor does not generate excitation flux, the four working surfaces of the armature 9 are in a force balance state, and the armature 9 is in a neutral position under the fixing action of the special-shaped spring 11; the piston rod 4 is fixedly connected to the armature 9 and is also in a neutral position. At this time, the overlapping areas of the high-pressure groove a3, the low-pressure groove b3 and the control groove c1 are the same, and the effective thrust generated by the control pressure Pc on the piston rod 4 is equal in magnitude to the effective thrust generated by the high pressure Ps on the piston rod 4, but in opposite directions. The piston rod 4 is in a balanced position under force balance and is stationary.

[0033] When forward current flows through control coil 7, the torque motor assembly generates excitation magnetic flux, and the four working surfaces of armature 9 rotate forward under the action of the differential magnetic flux. Armature 9 drives piston rod 4 to rotate forward synchronously. At this time, the overlapping area between high-pressure groove a3 and control groove c1 increases, while the overlapping area between low-pressure groove b3 and control groove c1 decreases. Control pressure Pc increases, and the effective thrust of control pressure Pc on piston rod 4 increases. Piston rod 4 moves axially in the forward direction until the overlapping areas between high-pressure groove a3, low-pressure groove b3, and control groove c1 become equal again. Control pressure Pc decreases to its initial value, and the effective thrust of control pressure Pc on piston rod 4 becomes equal to the effective thrust of high pressure Ps on piston rod 4. The force on piston rod 4 is balanced and it remains stationary.

[0034] Conversely, when reverse current flows through control coil 7, the torque motor assembly generates reverse excitation magnetic flux, and the four working surfaces of armature 9 rotate in the opposite direction under the action of the differential magnetic flux. Armature 9 drives piston rod 4 in synchronous reverse rotation. At this time, the overlapping area between low-pressure groove b3 and control groove c1 increases, while the overlapping area between high-pressure groove a3 and control groove c1 decreases. Control pressure Pc decreases, and the effective thrust of control pressure Pc on piston rod 4 decreases. Piston rod 4 then moves axially in the opposite direction until the overlapping areas between high-pressure groove a3, low-pressure groove b3, and control groove c1 become equal. Control pressure Pc increases to its initial value, and the effective thrust of control pressure Pc on piston rod 4 becomes equal to the effective thrust of high pressure Ps on piston rod 4. The force on piston rod 4 is balanced, and it remains stationary.

[0035] The piston rod 4 of the servo cylinder of the present application has a linear relationship with the input signal. When the input signal is a square wave, a triangle wave, a sine wave, etc., the output displacement of the piston rod 4 is consistent with the waveform of the input signal, which can realize open-loop and closed-loop continuous control, improve the control accuracy and dynamic response speed, and meet the requirements of various working conditions.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A miniature electro-hydraulic servo cylinder, comprising a hydraulic cylinder assembly and a torque motor assembly connected in a coordinated manner, characterized in that: The hydraulic cylinder assembly includes a cylinder body (1), and a piston rod (4) is movably sleeved in the cylinder body (1); the torque motor assembly includes a connecting seat (6) connected to the cylinder body (1), an armature (9) is provided on the connecting seat (6), and the armature (9) is fixed to the connecting seat (6) through a special-shaped spring (11) provided thereon, and a control coil (7) is provided on both sides of the armature (9); the piston rod (4) is fixed to the cylinder body (1) and the connecting seat (6) through a piston sleeve (3) sleeved thereon, and the piston rod (4) is connected to the armature (9) after passing through the cylinder body (1) and the connecting seat (6), and the control coil (7) is energized to drive the armature (9) to drive the piston rod (4) to rotate in the piston sleeve (3), and the change of the control pressure Pc generated when the piston rod (4) moves realizes the axial movement of the piston rod (4), and the closed-loop control of the servo cylinder is realized by feedback of the displacement by the linear displacement sensor (13) provided in the connecting seat (6); The piston rod (4) and the piston sleeve (3) are respectively provided with a left concentric ring (2) and a right concentric ring (5) at both ends thereof, and the right concentric ring (5) is provided at one end close to the armature (9); the piston rod (4) is provided with a first convex ring (16), a second convex ring (17), a high-pressure oil inlet hole a2, a low-pressure oil inlet hole b2, a high-pressure groove a3, and a low-pressure groove b3 in sequence from the left concentric ring (2) to the right concentric ring (5), and the high-pressure oil inlet hole a2 is provided between the left concentric ring (2) and the first convex ring (16). 6) on the piston rod (4); the low-pressure oil inlet hole b2 is provided at the connection between the second convex ring (17) and the piston rod (4); the high-pressure groove a3 and the low-pressure groove b3 are provided on the second convex ring (17); and the high-pressure oil inlet hole a2 is communicated with the high-pressure groove a3, and the low-pressure oil inlet hole b2 is communicated with 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 (17), and the working edges of the high-pressure groove a3 and the low-pressure groove b3 are oblique edges; The piston sleeve (3) is stepped into the cylinder body (1); the closed cavity formed between the piston sleeve (3), the left concentric ring (2) and the first convex ring (16) is the high-pressure cavity A; the closed cavity formed between the first convex ring (16), the piston sleeve (3) and the second convex ring (17) is the low-pressure cavity B; the closed cavity between the piston sleeve (3), the second convex ring (17) and the right concentric ring (5) is the control cavity C; The piston sleeve (3) is provided with a high-pressure hole a1, a low-pressure hole b1, and a control groove c1 in sequence from the left concentric ring (2) to the right concentric ring (5). The high-pressure hole a1 is connected to the high-pressure chamber A, the low-pressure hole b1 is connected to the low-pressure chamber B, and the control groove c1 is connected to the control chamber C. The high-pressure hole a1 and the low-pressure hole b1 are radially uniformly distributed channels, and the control groove c1 is a pair of centrally symmetrically distributed inclined grooves. The high-pressure port P of the cylinder body (1) is connected to the piston sleeve ( 3), the high-pressure hole a1 of the piston sleeve (3), the high-pressure oil inlet hole a2 of the piston rod (4) are connected to the high-pressure groove a3 of the piston rod; the low-pressure port Q of the cylinder body (1) is connected to the low-pressure groove b3 of the piston rod (4) through the low-pressure hole b1 of the piston sleeve (3), the low-pressure oil inlet hole b2 of the piston rod (4); the high-pressure groove a3 and the low-pressure groove b3 of the piston rod (4) and the control groove c1 corresponding to the piston sleeve (3) are used in conjunction to form a hydraulic damping half-bridge; The working area As of the high-pressure chamber A on the high-pressure chamber side of the piston rod (4) and the working area Ac of the control chamber C on the control chamber side are related by the equation Ps*As=Pc*Ac at any equilibrium position, where Ps is the high pressure of the high-pressure chamber A and Pc is the control pressure of the control chamber C.

2. A miniature electro-hydraulic servo cylinder according to claim 1, characterized in that: The left concentric ring (2) and the right concentric ring (5) are both made of wear-resistant materials.

3. The miniature electro-hydraulic servo cylinder according to claim 1, characterized in that: The piston rod (4) is connected to the armature (9) via a pin; the outer cover of the connecting seat (6) is provided with an end cover (15), and the end cover (15) is fixed to the connecting seat (6) via screws.

4. The miniature electro-hydraulic servo cylinder according to claim 1, characterized in that: Two groups of coil frames (10) wound with control coils (7) are embedded on the front and rear sides of the armature (9), two pole shoes (14) are embedded on the upper and lower sides of the armature (9), four magnets (8) are arranged between the two pole shoes (14), a collar (12) is provided on the side of the armature (9) away from the cylinder body (1), the collar (12) is connected to the connecting seat (6), and a linear displacement sensor (13) connected to the armature (9) is provided in the collar (12), and the displacement of the armature (9) is detected by the linear displacement sensor (13) to perform closed-loop control.

5. The miniature electro-hydraulic servo cylinder according to claim 4, characterized in that: A sealing ring is provided between the piston sleeve (3) and the cylinder body (1) step, and a sealing ring is provided between the piston sleeve (3) and the connecting seat (6) to prevent internal leakage of the servo cylinder; a sealing ring is provided between the cylinder body (1) and the piston rod (4), a sealing ring is provided on the mating surface of the connecting seat (6) and the coil skeleton (10), a sealing ring is provided between the connecting seat (6) and the cylinder body (1), and a sealing ring is provided between the connecting seat (6) and the collar (12) to prevent external leakage of the servo cylinder.

Images