A claw-pole magnetic levitation torque motor

Abstract

The claw pole type magnetic suspension torque motor comprises a coaxial and gap matched stator assembly and rotor assembly; the stator assembly comprises an end cover, claw poles, a coil framework, coils and a magnetic conducting sleeve; the claw poles comprise upper claw poles and lower claw poles; the cavity formed between the upper claw poles and the lower claw poles is provided with the coil framework, and the coils are wound on the coil framework; the rotor assembly comprises an annular shell, permanent magnets, a base and a rotating shaft; the annular shell is sleeved outside the claw poles; the bottom of the annular shell is provided with the base; the base is provided with a base shoulder; a blind hole is formed in the center of the base shoulder; the lower end of the rotating shaft is fixedly arranged in the blind hole; the upper end of the rotating shaft passes through the magnetic conducting sleeve of the stator assembly upwards; the stator assembly is assembled with the rotating shaft of the rotor assembly through gap matching by means of the magnetic conducting sleeve. The motor does not need additional zero adjusting screws and zero adjusting springs; the rotor can be accurately suspended in the axial and circumferential middle positions under the magnetic force between the stator and the rotor; and the motor has the advantages of high stability, large rotation angle range and high torque density.

Description

Technical Field

[0001] This invention relates to a torque motor, and more particularly to a claw-pole magnetic levitation torque motor. Background Technology

[0002] Electro-hydraulic control systems, characterized by high power-to-weight ratio, overload protection, and stepless speed regulation, are widely used in critical fields such as aerospace, engineering machinery, and robotics. As control and regulating elements, hydraulic valves are used to regulate oil pressure, flow rate, or flow direction, playing a crucial role in the overall system performance. Structurally, almost all valves consist of a valve core, valve body, and an electro-mechanical converter that drives the valve core. The electro-mechanical converter, acting as a bridge between the electrical and hydraulic components of a hydraulic valve, is an indispensable key component. A moving-iron torque motor is a rotary electro-mechanical converter widely used in servo valves. It generates a control flux through a control coil, which interacts with the polarized flux generated by a permanent magnet to create a differential action, outputting angular displacement.

[0003] Current moving iron torque motors have small output angular displacement and negative magnetic spring stiffness, making them unable to automatically fix in the neutral position. They require the use of zero-adjustment springs and zero-adjustment screws to stabilize them in the neutral position, which makes the adjustment process difficult, inaccurate, and results in a more complex structure. Summary of the Invention

[0004] To overcome the above problems, this invention provides a claw-pole magnetic levitation torque motor that utilizes the magnetic force generated by the polarization flux between the stator and rotor.

[0005] The technical solution adopted in this invention is: a claw-pole magnetic levitation torque motor, comprising a stator assembly and a rotor assembly that are coaxial and clearance-fitted;

[0006] The stator assembly includes an end cover, claw poles, a coil frame, a coil, and a magnetic sleeve. The claw poles are located below the end cover and include an upper claw pole with downward-facing claw teeth and a lower claw pole with upward-facing claw teeth. The upper and lower claw poles are fitted together, and the coil frame is installed in the cavity formed between them. The coil frame is fixed to the claw poles by an interference fit, and a coil is wound on the coil frame. The end cover, claw poles, and coil frame are coaxially arranged, and the end cover, claw poles, and coil frame are provided with a circular through hole along the axis. The inner diameter of the circular through hole is interference-fitted with the outer diameter of the magnetic sleeve. The magnetic sleeve passes through the circular through hole, and the coil frame and claw poles are fixed to the magnetic sleeve by an interference fit. The upper end of the magnetic sleeve is fixedly connected to the end cover.

[0007] The rotor assembly includes an annular shell, a permanent magnet, a base, and a rotating shaft. The annular shell is fitted over the claw poles. The bottom of the annular shell is provided with a base, and the base has a base shoulder. A blind hole is opened in the center of the base shoulder, and multiple positioning rods for positioning the permanent magnet are provided circumferentially along the edge of the base shoulder. The lower end of the rotating shaft is fixedly installed in the blind hole, and the upper end of the rotating shaft passes upward through the magnetic sleeve of the stator assembly.

[0008] The inner wall of the annular shell is provided with multiple permanent magnets spaced circumferentially, and the multiple permanent magnets correspond to multiple positioning rods inserted into the holes; the magnetic poles of two adjacent permanent magnets are opposite in the radial direction; the air gap between the claw pole teeth of the upper claw pole and the claw pole teeth of the lower claw pole and the permanent magnet is the working air gap; the radial spacing of the working air gap remains constant, and the area of ​​the working air gap changes with the rotation of the rotor assembly.

[0009] The rotating shaft, outer shell, claw pole, coil frame, and magnetic sleeve are all made of high magnetic permeability materials; the end cap and base are made of non-magnetic materials; the magnetization direction of the permanent magnet points to the center of the claw pole.

[0010] When the rotor assembly is in the circumferential center position, each claw pole tooth faces two adjacent permanent magnets with opposite magnetic poles and the facing area is the same. The cogging torque components of the two permanent magnets on the claw pole teeth are equal in magnitude and opposite in direction, and the rotor assembly is in force balance and suspended in the axial center position. After the rotor assembly generates an angular displacement deviating from the circumferential center position, it is subjected to a cogging torque that returns it to the circumferential center position. After the rotor assembly generates a displacement deviating from the axial center position, it is subjected to an axial restoring force that returns it to the axial center position.

[0011] When the coil is energized, an axial magnetic flux is generated in the torque motor. This magnetic flux is converted into a radial magnetic flux by the claw poles. The converted radial magnetic flux is superimposed with the polarization magnetic flux generated by the permanent magnet in the air gap between the rotor assembly and the stator assembly. This causes the magnetic flux density in one part of the air gap to increase and the magnetic flux density in another part of the air gap to decrease, so that the rotor assembly generates angular displacement under differential action.

[0012] Furthermore, the end cap has a threaded hole on its side, and the end cap is fixedly connected to the magnetic sleeve through the threaded hole; the base has a threaded hole on its side, and the base is fixedly connected to the rotating shaft through the threaded hole.

[0013] Furthermore, the axial cross-section of the claw pole teeth is an isosceles trapezoid or rectangle, and the claw pole teeth of the upper claw pole and the claw pole teeth of the lower claw pole are alternately distributed in the circumferential direction.

[0014] Furthermore, the axial cross-section of the permanent magnet is rectangular or fan-shaped, and the height of the top surface of the permanent magnet is slightly higher than the height of the top surface of the claw pole.

[0015] The beneficial effects of this invention are:

[0016] (1) Large rotation angle range. The present invention adopts a radial air gap structure, and there is no mechanical limit during rotation. The rotation angle range can be changed by adjusting the structural parameters of the claw pole, so as to achieve a large rotation angle that cannot be achieved by traditional moving iron torque motors.

[0017] (2) It has positive magnetic spring stiffness and can automatically adjust the center position in the axial and circumferential directions. Through the parameter design of the stator assembly and rotor assembly, the present invention ensures that the rotor assembly will be subjected to a force or torque that returns it to the center position after it deviates from the center position in the axial or circumferential directions. The center position adjustment is achieved by utilizing the magnetic force between the stator and rotor, without the need for additional zero-adjustment screws and zero-adjustment springs.

[0018] (3) High torque density. Since the stator adopts a claw pole structure and an external rotor, and there is no need to ensure a constant torque range so that the pole shoe utilization rate can reach 100%, the present invention has a higher torque density than the traditional moving iron torque motor. Attached Figure Description

[0019] Figure 1 This is an assembly diagram of the present invention.

[0020] Figure 2 Exploded view of the present invention

[0021] Figure 3 A schematic diagram of the stator assembly.

[0022] Figure 4 A schematic diagram of the rotor assembly.

[0023] Figure 5 Schematic diagram of the working principle after applying current to the coil

[0024] Figure 6 This is a schematic diagram showing the relative positions of the claw pole teeth and the permanent magnet when the rotor is in the neutral position.

[0025] Figure 7 Angular displacement-control current characteristic curve

[0026] Figure 8 The moment-angle characteristic curve of the coil when there is no current.

[0027] Figure 9 The axial displacement-axial restoring force characteristic curve when the coil has no current.

[0028] Figure 10 Moment-angle characteristic curve after applying current to the coil

[0029] Explanation of reference numerals in the attached drawings: 1. Shaft; 2. End cap; 2a. Threaded hole in end cap; 3. Outer shell; 4. Base; 4a. Threaded hole in base; 4b. Base positioning rod; 4c. Base shoulder; 5A. First permanent magnet; 5B. Second permanent magnet; 5C. Third permanent magnet; 6. Coil frame; 7. Coil; 8A. Upper claw pole; 8B. Lower claw pole; 9. Magnetic sleeve; S a The area of ​​the first permanent magnet facing the upper claw pole; S b The area of ​​the second permanent magnet facing the upper claw pole; S c The area of ​​the second permanent magnet facing the lower claw pole; S d The area of ​​the third permanent magnet facing the lower claw pole. Detailed Implementation

[0030] The technical solution of this invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Referring to the accompanying drawings, the stator assembly and rotor assembly are coaxial and clearance-fitted.

[0034] The stator assembly includes an end cover 2, claw poles 8, a coil frame 6, a coil 7, and a magnetic sleeve 9. The claw poles 8 are located below the end cover 2 and include an upper claw pole 8A with the claw pole teeth facing downwards and a lower claw pole 8B with the claw pole teeth facing upwards. The upper and lower claw poles have the same structure. The axial cross section of the claw pole teeth is an isosceles trapezoid, a rectangle, or other combined curves, alternating curves, etc. The upper claw poles 8A and the lower claw poles 8B are joined together, and the claw pole teeth of the upper claw pole 8A and the lower claw pole 8B are alternately distributed in the circumferential direction.

[0035] A coil frame 6 is installed in the cavity formed between the upper claw pole 8A and the lower claw pole 8B. The coil frame 6 is fixedly connected to the claw pole 8 by an interference fit. A coil 7 is wound on the coil frame 6. The end cover 2, the claw pole 8 and the coil frame 6 are arranged coaxially. The end cover 2, the claw pole 8 and the coil frame 6 are provided with a circular through hole along the axis. The inner diameter of the circular through hole is interference-fitted with the outer diameter of the magnetic sleeve 9. The magnetic sleeve 9 is inserted into the circular through hole. The coil frame 6 and the claw pole 8 are both fixedly connected to the magnetic sleeve 9 by an interference fit. The end cover 2 is provided with an end cover threaded hole 2a on the side. The end cover 2 is fixedly connected to the magnetic sleeve 9 through the end cover threaded hole 2a.

[0036] The rotor assembly includes an annular shell 3, a permanent magnet 5, a base 4, and a rotating shaft 1. The annular shell 3 is fitted over the claw pole 8. The bottom of the annular shell 3 is provided with a base 4. The base 4 is provided with a base shoulder 4c. A blind hole is opened in the center of the base shoulder 4c. Multiple positioning rods 4b for positioning the permanent magnet 5 are provided circumferentially along the edge of the base shoulder 4c. The lower end of the rotating shaft 1 is fixedly set in the blind hole, and the upper end of the rotating shaft 1 passes upward through the magnetic sleeve 9 of the stator assembly. The base 4 is provided with a base threaded hole 4a on the side, and the base 4 is fixedly connected to the rotating shaft 1 through the base threaded hole 4a.

[0037] Multiple permanent magnets 5 are spaced circumferentially along the inner wall of the annular outer shell 3, with each permanent magnet 5 corresponding to a multiple positioning rod 4b. The axial cross-section of each permanent magnet 5 is rectangular or fan-shaped, and the top surface height of the permanent magnet 5 is slightly higher than the top surface height of the claw pole 8. Three consecutive permanent magnets 5 are respectively referred to as the first permanent magnet 5A, the second permanent magnet 5B, and the third permanent magnet 5C. The magnetic poles of the first permanent magnet 5A and the second permanent magnet 5B are opposite, and the magnetic poles of the second permanent magnet 5B and the third permanent magnet 5C are opposite. When the rotor assembly is in the circumferential center position, the area S directly opposite to the area of ​​the upper claw pole 8A and the first permanent magnet 5A is... a The area S between the upper claw pole 8A and the second permanent magnet 5B is directly opposite. b Equal in size; the area S directly opposite the lower claw pole 8B and the second permanent magnet 5B c The area S directly opposite the lower claw pole 8B and the third permanent magnet 5C d Equal in size; the area S directly opposite the second permanent magnet 5B and the upper claw pole 8A bThe area S between the second permanent magnet 5B and the lower claw pole 8B is directly opposite. c The sizes are equal; the air gap between the claw pole teeth of the upper claw pole 8A and the claw pole teeth of the lower claw pole 8B and the permanent magnet 5 is the working air gap. The radial spacing of the working air gap remains constant, and the area of ​​the working air gap changes with the rotation of the rotor assembly.

[0038] The rotating shaft 1, outer shell 3, claw pole 8, coil frame 6, and magnetic sleeve 9 are all made of materials with high magnetic permeability; the end cap 2 and base 4 are made of non-magnetic materials; the magnetization direction of the permanent magnet 5 is pointed to the center of the claw pole 8.

[0039] During assembly, the stator assembly is assembled with the rotor assembly's shaft 1 via a clearance fit using the magnetic sleeve 9, forming a claw-pole magnetic levitation torque motor with positive magnetic spring stiffness. The base 4, permanent magnet 5, housing 3, and shaft 1 are fixed together using industrial adhesives, bolts, etc., to form a rotor assembly. The housing 3 is positioned by the shoulder 4c and then fixed to the base 4 using industrial adhesives. The permanent magnet 5 is positioned by the positioning rod 4b and then fixed to the housing 3 using industrial adhesives. The base 4 is fixed to the shaft using bolts through threaded holes 4a.

[0040] The specific principle is as follows: When no current is applied to the coil, this invention utilizes the restoring force and cogging torque existing between the stator and rotor to suspend the rotor in the axial and circumferential neutral position. The cogging torque always attempts to align the centerline of the permanent magnet with the centerline of the stator teeth or the centerline of the stator slot. In this invention, when the centerline of the stator slot coincides with the centerline of the permanent magnet, the forces generated by the polarization flux on both sides of the claw pole teeth cancel each other out, and the cogging torque is zero. When the rotor is given an angular velocity to rotate counterclockwise, the tangential components of the polarization flux cannot completely cancel each other out, and the stator experiences a counterclockwise torque. According to the principle of action and reaction, the permanent magnet experiences a clockwise torque, attempting to return it to its initial position. Figure 5 A schematic diagram illustrating the working principle after the coil is energized is provided. The control magnetic flux generated by the coil interacts with the polarization magnetic flux generated by the permanent magnet at working air gaps ①, ②, ③, and ④, causing the magnetic flux density at air gaps ① and ③ to decrease, while the magnetic flux density at air gaps ② and ④ to increase. The rotor then experiences a counter-clockwise torque and begins to rotate. After the coil is de-energized, the rotor experiences axial and circumferential magnetic forces and automatically returns to its neutral position.

[0041] Figure 7 The angular displacement-control current characteristic curve is given. With counterclockwise as the positive direction, when the rotor angular displacement ranges from -2.5° to 2.5°, the rotor angular displacement increases linearly with the increase of control current, exhibiting good linearity, which is beneficial for proportional control. Figure 8 , Figure 9 , Figure 10 This demonstrates that the present invention possesses positive magnetic spring stiffness in both the axial and circumferential directions. Figure 8 The torque-angle characteristic curve when the coil has no current is given. When the rotor is given a counterclockwise angular displacement, the rotor will be subjected to a cogging torque in the clockwise direction. This cogging torque always tries to make the rotor return to the circumferential center position. Figure 9 The characteristic curves of axial displacement-axial restoring force when there is no current in the coil are given. When the rotor is given an axial displacement, the rotor will be subjected to an axial restoring force in the opposite direction to the axial displacement. This axial restoring force always tries to make the rotor return to the axial neutral position. Figure 10 The torque-angle characteristic curve after the coil is loaded with current is given. When the rotor is in the neutral position and the magnetomotive force generated by the current is 200A, the output torque generated by this invention can reach 208mNm. As the rotor misalignment angle increases, the output torque gradually decreases until it becomes zero.

[0042] The embodiments described in this specification are merely examples of implementations of the inventive concept. The scope of protection of this invention should not be considered as limited to the specific forms stated in the embodiments. The scope of protection of this invention also extends to equivalent technical means that can be conceived by those skilled in the art based on the inventive concept.

Claims

1. A claw-pole type magnetic levitation torque motor, characterized in that: Includes coaxial stator and rotor assemblies with clearance fit; The stator assembly includes an end cap (2), claw poles (8), a coil frame (6), a coil (7), and a magnetic sleeve (9). The claw poles (8) are located below the end cap (2) and include an upper claw pole (8A) with its claw teeth facing downwards and a lower claw pole (8B) with its claw teeth facing upwards. The upper claw poles (8A) and lower claw poles (8B) are closed together, and the coil frame (6) is installed in the cavity formed between the upper claw poles (8A) and lower claw poles (8B). The coil frame (6) and the claw poles (8) are connected by a magnetic field. The coil (7) is wound on the coil frame (6) with an interference fit. The end cap (2), claw pole (8) and coil frame (6) are coaxially arranged. The end cap (2), claw pole (8) and coil frame (6) are provided with a circular through hole along the axis. The inner diameter of the circular through hole is interference fit with the outer diameter of the magnetic sleeve (9). The magnetic sleeve (9) is inserted into the circular through hole. The coil frame (6) and claw pole (8) are both fixed to the magnetic sleeve (9) by interference fit. The upper end of the magnetic sleeve (9) is fixedly connected to the end cap (2). The rotor assembly includes an annular shell (3), a permanent magnet (5), a base (4), and a rotating shaft (1). The annular shell (3) is fitted over the claw pole (8). The bottom of the annular shell (3) is provided with a base (4). The base (4) is provided with a base shoulder (4c). A blind hole is opened in the center of the base shoulder (4c). Multiple positioning rods (4b) for positioning the permanent magnet (5) are provided along the circumferential direction on the edge of the base shoulder (4c). The lower end of the rotating shaft (1) is fixedly set in the blind hole, and the upper end of the rotating shaft (1) passes upward through the magnetic sleeve (9) of the stator assembly. The inner wall of the annular shell (3) is provided with multiple permanent magnets (5) spaced circumferentially. The multiple permanent magnets (5) correspond to multiple positioning rods (4b) inserted into the space. The magnetic poles of two adjacent permanent magnets (5) are opposite in the radial direction. The air gap between the claw pole teeth of the upper claw pole (8A), the claw pole teeth of the lower claw pole (8B) and the permanent magnets (5) is the working air gap. The radial spacing of the working air gap remains constant. The area of ​​the working air gap changes with the rotation of the rotor assembly. The rotating shaft (1), outer shell (3), claw pole (8), coil frame (6), and magnetic sleeve (9) are all made of high magnetic permeability materials; the end cap (2) and base (4) are made of non-magnetic materials; the permanent magnet (5) is magnetized in the direction of the center of the claw pole (8); When the rotor assembly is in the circumferential center position, each claw pole tooth is directly opposite to two adjacent permanent magnets (5) with opposite magnetic poles and the same area is directly opposite. The cogging torque components of the two permanent magnets (5) on the claw pole tooth are equal in magnitude and opposite in direction. The rotor assembly is in force balance and suspended in the axial center position. After the rotor assembly generates an angular displacement that deviates from the circumferential center position, it is subjected to a cogging torque that returns it to the circumferential center position. After the rotor assembly generates a displacement that deviates from the axial center position, it is subjected to an axial restoring force that returns it to the axial center position. When the coil (7) is energized, an axial magnetic flux is generated in the torque motor. The axial magnetic flux is converted into a radial magnetic flux by the claw pole (8). The converted radial magnetic flux is superimposed with the polarization magnetic flux generated by the permanent magnet (5) in the air gap between the rotor assembly and the stator assembly. This causes the magnetic flux density in one part of the air gap to increase and the magnetic flux density in another part of the air gap to decrease, so that the rotor assembly generates angular displacement under differential action.

2. The claw-pole magnetic levitation torque motor as described in claim 1, characterized in that: The end cap (2) has an end cap threaded hole (2a) on its side, and the end cap (2) is fixedly connected to the magnetic sleeve (9) through the end cap threaded hole (2a); the base (4) has a base threaded hole (4a) on its side, and the base (4) is fixedly connected to the rotating shaft (1) through the base threaded hole (4a).

3. The claw-pole magnetic levitation torque motor as described in claim 1, characterized in that: The axial cross section of the claw pole teeth is an isosceles trapezoid or rectangle, and the claw pole teeth of the upper claw pole (8A) and the claw pole teeth of the lower claw pole (8B) are alternately distributed in the circumferential direction.

4. A claw-pole magnetic levitation torque motor as described in claim 1, characterized in that: The axial cross section of the permanent magnet (5) is rectangular or fan-shaped, and the top surface height of the permanent magnet (5) is slightly higher than the top surface height of the claw pole (8).

Images