A reluctance spherical stepping motor

Abstract

The present invention relates to a reluctance spherical stepper motor, comprising an outer stator, a rotor body, a base, a universal ball, an output shaft, a flange, a connecting frame and bolts; the rotor body comprises a rotor, a rotor spherical shell with a slot and a rotor embedded therein, the rotor is a small tooth structure and has no winding, the output shaft is connected to the rotor through the rotor shell and connected to the top flange, the outer stator comprises a winding coil, a stator shell and a stator core; the stator spherical shell is mounted on the base by bolts, the universal ball is fixed to the stator spherical shell by bolts and contacts the rotor body, and the universal ball is composed of a cylinder, a nylon ball and a stainless steel ball. The present invention can realize three-degree-of-freedom motion, its motor structure is simple, the system complexity is low, the control accuracy of the spherical motor is improved, and the complexity of the control system is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of spherical motor design, and in particular relates to a reluctance spherical stepping motor. Background Art

[0002] As the main power source in the industrial field, electric motors, with their convenient energy transmission, accurate control, and direct integration with computers, are driving industrial progress while also constantly adapting to new requirements of industrial applications. With the development of industrial automation's realistic requirements for industrial robots, especially multi-degree-of-freedom motion manipulators, the movement mode of motors has begun to develop from simple one-dimensional circular rotation to multi-degree-of-freedom motion.

[0003] At present, mature robotic arms all use a combination of multiple single-degree-of-freedom motors in series and parallel, combined with a mechanical motion conversion mechanism, and each motor performs a single-dimensional motion. At present, the serial robotic arm has a mature theoretical system, has made significant progress and has been widely used. However, the defects brought by the combination of multiple single-degree-of-freedom motors still seriously limit the use prospects of industrial robotic arms: (1) Multiple motors plus complex transmission mechanisms cause the whole set of robotic arms to have a larger volume as the motion complexity increases, which contradicts the requirement that the smaller the space, the higher the motion complexity of the robotic arm. (2) The position error of the end actuator comes from the accumulation and amplification of errors in each joint, resulting in a larger error for the robotic arm with higher motion complexity. (3) The complex transmission mechanism reduces the reliability of the entire system. (4) Multiple single-degree-of-freedom motors are controlled separately, resulting in low utilization of each motor, low transmission efficiency and low motion execution speed. Therefore, the development of spherical motors that can perform multi-degree-of-freedom motion with a single motor has always attracted the attention of scholars from various countries. Summary of the invention

[0004] The purpose of the present invention is to provide a reluctance spherical stepping motor. The motor has a small step angle and can realize three-degree-of-freedom motion of rotation and tilt. The overall structure of the motor is very simple and has the advantages of small size, low complexity, simple drive control and position detection, and high control accuracy.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A reluctance spherical stepper motor comprises a rotor, a rotor shell, an outer stator, a base, an end cover, a universal ball, a bolt and an output shaft; the rotor adopts a spherical structure, and the center of the rotor is hollowed out; the inner side of the rotor shell is fixedly connected to the rotor teeth to form a hollow sphere; the output shaft is fixedly connected to the upper part of the rotor shell, and the end of the output shaft passes through the end cover and is equipped with a flange; the outer stator comprises a stator core, a winding coil and a stator shell; the stator winding coil is a concentrated winding coil wound on the stator core; the upper part of the stator shell is connected to the end cover, and the lower part is installed on the base by bolts, and the universal ball is fixed to the stator shell by bolts; the universal ball is composed of a tray, a nylon ball and a stainless steel ball.

[0007] Furthermore, the stator pole shoe adopts a spherical arc surface and has small teeth on it, which cooperate with the rotor small teeth.

[0008] Furthermore, the spherical motor is an inner rotor and outer stator type motor, the rotor and the outer stator are both spherical structures, no windings, commutators or slip rings are arranged on the rotor, and each stator core of the outer stator is wound with concentrated winding coils.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0010] 1. The multi-degree-of-freedom spherical motor of the present invention greatly simplifies the structure of the mechanical system and reduces the production cost. It is small in size, light in weight, and has high dynamic and static performance of the system.

[0011] 2. The support method of installing a universal ball on the stator spherical shell proposed in the present invention can effectively reduce the friction force when the spherical motor moves, and its friction force is much smaller than the arc surface contact structure.

[0012] 3. The stator proposed by the present invention is equipped with three groups of coil units, of which one group of coils on the equator has eight in total, which meets the spin motion of the spherical motor, and two groups are distributed along the equator at 32.4° up and down, and each group has four magnetic poles evenly distributed, which meets the tilt motion of the spherical motor. It has strong mechanical strength, is not easy to deform, and the simple structural design realizes high-precision three-dimensional limited angular motion. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the reluctance spherical stepping motor of the present invention;

[0014] Figure 2 It is a structural diagram of the output shaft and the rotor body of the present invention;

[0015] Figure 3 This is a structural diagram of the universal ball of the present invention;

[0016] Figure 4This is an example diagram of the motor rotation motion of the present invention;

[0017] Figure 5 This is an example diagram of the tilting motion of the motor of the present invention;

[0018] Figure 6 This is an example diagram of the motor coordinate system of the present invention;

[0019] Numbers in the figure: 1 rotor; 2 rotor shell; 3 outer stator; 4 stator core; 5 winding coil; 6 stator housing; 7 base; 8 end cover; 9 universal ball; 10 bolt; 11 output shaft; 12 flange; 13 stator pole shoe; 14 tray; 15 stainless steel ball; 16 nylon ball. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0021] like Figure 1 As shown, a reluctance spherical stepper motor of the present invention comprises a rotor 1, a rotor shell 2, an outer stator 3, a base 7, an end cover 8, a universal ball 9, a bolt 10, an output shaft 11 and a flange 12, etc. The outer stator 3 comprises a stator core 4, a winding coil 5 and a stator shell 6, the rotor body comprises the rotor 1 and the rotor shell 2, and the universal ball 9 comprises a tray 14, a stainless steel ball 15 and a nylon ball 16. The rotor 1 adopts a spherical structure, and the center of the rotor 1 is hollowed out; the inner side of the rotor shell 2 is fixedly connected with the rotor small teeth to form a hollow sphere; one end of the output shaft 11 is fixedly connected with the upper part of the rotor shell 2, and the end of the output shaft 11 passes through the end cover 8 and is equipped with a flange 12; the winding coil 5 is a concentrated winding coil wound on the stator core 4; the upper part of the stator shell 6 is connected with the end cover 8, and the lower part is installed on the base 7 by bolts 10, and the universal ball 9 is fixed on the rotor shell 2 by bolts.

[0022] like Figure 1 , Figure 2As shown, the rotor 1 is a spherical structure, and the rotor teeth are evenly distributed on the equator of the sphere every 7.2°, and then every 7.2° deflection along the latitude is a layer, a total of 13 layers, and 50 teeth in each layer. Since magnetic conductive materials such as iron and cobalt have large rigidity and are brittle, the rotor teeth are easily broken during operation, so the present invention adopts nickel plating to improve its mechanical properties. Nickel has excellent mechanical properties, especially it has good corrosion resistance, and its hardness is very high, wear resistance is very good, and it has good "profiling properties". No grinding is required after plating. Nickel is very suitable for surface strengthening of mechanical parts. Therefore, the present invention adopts nickel plating of the rotor to increase the mechanical properties such as hardness and wear resistance of the rotor. The rotor 1 is wrapped in a lightweight rotor spherical shell 2 made of PC material, and the center of the rotor 1 is hollowed out, which is conducive to reducing the rotational inertia of the motor. The rotor 1 is connected to an output shaft 11, which passes through the rotor spherical shell 2 and is connected to the flange 12 for outputting electromagnetic torque.

[0023] like Figure 1 , Figure 2 As shown, the outer stator 3 of the motor is made of two hemispherical shells, made of electrical pure iron material, fixedly mounted on the base 7, and three layers of stator cores 4 made of the same material are fixed inside, which are evenly distributed at latitude angles of -32.4°, 0°, and 32.4°. Eight stator cores 4 are arranged along the spherical equator of the outer stator 3, and are evenly distributed at 45° longitude angles. There are 4 stator cores 4 on the cross section at latitude angles of -32.4° and 32.4°, and are evenly distributed at 90° longitude angles. A stator pole shoe with a spherical arc surface is installed at the end of each stator core 4, and 5*5 stator teeth are evenly distributed on each stator pole shoe, and adjacent stator teeth are 6.9° apart. Nickel plating is also performed to increase mechanical properties. The stator core 4 is fixed with a winding coil 5 of a centralized structure, and the coil is wound with enameled wire.

[0024] like Figure 1 , Figure 2 , Figure 3 As shown, the tray 14, nylon balls 16 and stainless steel balls 15 together constitute the universal ball 9. The stainless steel balls 15 are arranged in the tray 14, and the nylon balls 16 are arranged on the stainless steel balls 15, which are fixed to the base 7 by bolts 10. The universal ball is used to contact the rotor, which is a point contact method. The advantage of this method is that it can significantly reduce the friction during the operation of the spherical motor.

[0025] The working principle of the present invention is as follows:

[0026] For ease of understanding and analysis, the motion of a reluctance spherical stepper motor can be decomposed into the synthesis of two degrees of freedom: spin motion and tilt motion. Both motions are based on the principle of minimum magnetic resistance, finding the appropriate deflection angle between the stator and the rotor, energizing the stator phase to generate electromagnetic torque, and applying different energization strategies to complete stepping motion in any direction. The motion characteristics of the spherical motor can be analyzed by measuring the position, speed, and angular velocity of the shaft.

[0027] Regarding the spinning motion, take the stator and rotor of the motor cross section for an overview. Figure 4 As shown, when only the coil at 0° latitude (using a coordinate system similar to the earth) is considered, the spinning motion of the spherical motor is the same as that of an ordinary reactive stepper motor. Figure 4 At the two-stage axis shown in the figure, the stator phase CC′ and the rotor teeth are in a tooth-to-tooth state. At this time, the magnetic resistance on this straight line is the smallest, and the direction of the magnetic flux flows mainly along this line. The magnetic flux always closes along the path with the smallest magnetic resistance, and a tangential magnetic pull is generated due to the distortion of the magnetic field. At this time, the stator teeth at the two-stage axis of the stator phase AA′ are in a tooth-to-slot state relative to the rotor teeth. If only the stator phase AA′ is energized, the rotor teeth will rotate clockwise due to the tangential magnetic pull. The stator phases are energized in sequence in a continuous clockwise direction, and the rotor will then complete the spin motion. The tilt motion and spin motion of the reluctance spherical stepper motor are highly symmetrical, so the principle of the motor tilt motion can be understood by analyzing the energization effect of a single pair of rotor teeth and three sets of coils in the longitudinal section. The designed tilt stator phase-to-phase latitude angle is 32.4°, Figure 5 The cross-sectional view at 0° longitude angle shows that the stator phase FF′ and the rotor teeth are in a tooth-to-slot state. At this time, the stator teeth of the tilted stator phase are in a tooth-to-tooth state relative to the rotor teeth. When only the stator phase FF′ is energized, the rotor is deflected 3.6° counterclockwise by the tangential magnetic pull. According to a similar energization strategy, the rotor can continuously step and tilt.

[0028] Based on the above-mentioned ideal embodiment of the present invention, through the above-mentioned description, relevant staff can make various changes and modifications without departing from the technical idea of ​​the present invention. The technical scope of the present invention is not limited to the content of the specification, and its technical scope must be determined according to the scope of the invention.

Claims

1. A reluctance spherical stepper motor, characterized in that: The invention comprises a rotor (1), a rotor spherical shell (2), an outer stator (3), a base (7), an end cover (8), a universal ball (9), a bolt (10) and an output shaft (11); the rotor (1) adopts a spherical structure, and the center of the rotor (1) is hollowed out; the inner side of the rotor spherical shell (2) is fixedly connected to the rotor small teeth to form a hollow sphere; the output shaft (11) is fixedly connected to the upper part of the rotor spherical shell (2), and the end of the output shaft (11) passes through the end cover (8) and is equipped with a flange (12); the outer stator (3) comprises A stator core (4), a winding coil (5) and a stator housing (6); a stator pole shoe (13) is arranged on the stator core (4); the winding coil (5) is a concentrated winding coil wound on the stator core (4); the upper part of the stator housing (6) is connected to the end cover (8), and the lower part is installed on the base (7) by bolts (10); the universal ball (9) is fixed to the rotor spherical shell (2) by bolts; the universal ball is composed of a tray (14), a stainless steel ball (15) and a nylon ball (16); Three groups of winding coils are installed on the outer stator, of which one group on the equator has eight winding coils in total to meet the spinning motion of the spherical motor, and two groups are distributed along the equator at a deflection of 32.4° up and down, and each group has four magnetic poles evenly distributed to meet the tilting motion of the spherical motor; The motion of the reluctance spherical stepper motor is decomposed into the synthesis of two degrees of freedom: spin motion and tilt motion. The two motions are based on the principle of minimum magnetic resistance. The appropriate deflection angle between the stator and the rotor is found. The stator phase is energized to generate electromagnetic torque. Different energization strategies are applied to complete stepping motion in any direction. The motion characteristics of the spherical motor are analyzed by measuring the position, speed and angular velocity of the shaft. The rotor teeth are evenly distributed at intervals of 7.2° on the equator of the sphere, and then one layer is formed every 7.2° along the latitude, with a total of 13 layers, 50 teeth in each layer. The material of the rotor teeth is iron-cobalt material that is nickel-plated.

2. A reluctance spherical stepper motor as claimed in claim 1, characterized in that: The stator pole shoe (13) adopts a spherical arc surface and has small teeth on it, which cooperate with the rotor small teeth.

3. A reluctance spherical stepper motor as claimed in claim 1, characterized in that: The spherical motor is an inner rotor and outer stator type motor. The rotor (1) and the outer stator (3) are both spherical structures. No winding, commutator or slip ring is provided on the rotor (1). Each stator core (4) of the outer stator (3) is wound with a concentrated winding coil (5).

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