Method for positioning flat position angle of motor rotating shaft by utilizing cogging torque

Abstract

The invention relates to the technical field of motors, in particular to a method for positioning the flat position angle of a motor rotating shaft through cogging torque, and the method comprises the following steps: designing and manufacturing a die head with a positioning function; mounting the stator core and the die head in a matched manner, and positioning the stator core; mounting the casing and the die head in a matching manner, and positioning the angle after the casing and the stator core are assembled; a motor rotating shaft flat position in the rotor structure is fixed opposite to the center of the magnetic pole; and assembling all the assembled motor assemblies into a finished motor. After the motor is assembled, the rotating shaft of the motor is rotated for one circle under the condition that the winding is not electrified, and the flat positions of the rotating shaft of the motor are respectively locked at 12 positions of 0 degree, 30 degrees, 60 degrees, 90 degrees, 120 degrees, 150 degrees, 180 degrees, 210 degrees, 240 degrees, 270 degrees, 300 degrees and 330 degrees. Compared with the prior art, the method for positioning the flat position angle of the rotating shaft of the motor by utilizing the cogging torque has the advantages that the flat position of the rotating shaft can be locked by utilizing the positioning torque, namely the cogging torque, of the motor when a motor winding is not electrified, so that the flat position of the rotating shaft of the motor is fixed at several appointed positions according to design requirements; the product design requirement is met, the structure complexity and the software control algorithm difficulty are reduced, the cost is reduced, the efficiency is improved, and the product market competitiveness is improved.

Description

[Technical field]

[0001] The present invention relates to the technical field of motors, and in particular to a method for positioning the flat angle of a motor rotating shaft by utilizing cogging torque. [Background technology]

[0002] The detent torque generated by the interaction between the permanent magnet and the iron core when the permanent magnet motor winding is not energized is also called cogging torque. Cogging torque is caused by the fluctuation of the tangential component of the interaction force between the permanent magnet and the armature teeth. When the rotor permanent magnet meets or separates from the stator teeth, the magnetic field of its attachment changes, causing the magnetic energy of the air between the permanent magnet and the stator teeth to change. The change in magnetic energy produces torque, namely detent torque or cogging torque.

[0003] Therefore, when the permanent magnet motor winding is not energized, the motor rotating shaft will be randomly locked in certain positions under the influence of the cogging torque, affecting the use of the product.

[0004] For example, for an electric toothbrush, the position of the bristles (the flat position of the motor shaft) needs to correspond to the position of the handle button, that is, the bristles (the flat position of the shaft) and the handle button need to be in the same direction, and the positional relationship between the bristles (the flat position of the motor shaft) and the handle button (motor installation position) needs to be accurately located.

[0005] There are two main types of existing brush head positioning solutions: 1. The brush head is locked by a mechanical structure when the power is off, and the locking mechanism is disengaged from the brush head when the power is on. This type of structure is complex, costly, and noisy. 2. To reduce the cogging torque, the drive software control algorithm is used to lock the brush head with the motor brake. The algorithm is complex and difficult, and the product needs to be powered on for a long time, resulting in high energy consumption, short charging cycle, and short battery life. [Summary of the invention]

[0006] In order to overcome the above problems, the present invention proposes a method for positioning the flat angle of a motor rotating shaft using cogging torque, which can effectively solve the above problems.

[0007] The present invention provides a technical solution to solve the above technical problem: a method for positioning the flat angle of a motor rotating shaft by using cogging torque is provided, comprising the following steps:

[0008] Step S1, designing and manufacturing a die head with a positioning function;

[0009] Step S2, installing the stator core and the die head together to position the stator core;

[0010] Step S3, installing the housing and the die head together, and positioning the angle between the housing and the stator core after assembly;

[0011] Step S4, the motor rotating shaft in the rotor structure is fixedly aligned with the center of the magnetic pole;

[0012] Step S5, assembling all assembled motor components into a finished motor;

[0013] Step S6, after the motor is assembled, rotate the motor shaft one circle without power to the winding, and the motor shaft is locked at 12 positions of 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, and 330° respectively.

[0014] Preferably, in step S1, a first key and a second key are provided on the die head, and the first key and the second key are distributed at an X angle, where the X angle is the angle between the center line of the stator slot and the center line of the stator tooth.

[0015] Preferably, the number of the first keys is less than or equal to the number of stator tooth slots in the stator core, and the first keys are evenly distributed on the die head.

[0016] Preferably, in step S2, the first key is inserted into the stator tooth slot in the stator core to position the stator core.

[0017] Preferably, in step S3, a positioning notch or other characteristic part with a positioning function matching the second key is provided on the casing, the positioning notch or other characteristic part with a positioning function is assembled with the second key, and then the stator core and the casing are fixed by gluing.

[0018] Preferably, a housing mounting hole is provided on the housing, and the housing mounting hole corresponds to the positioning notch.

[0019] Preferably, the center line of the positioning notch coincides with the center line of the stator tooth.

[0020] Preferably, in step S4, there is a method for fixing the flat position of the motor rotating shaft to face the center of the magnetic pole. The rotor core itself has a positioning keyway structure, and the keyway of the motor rotating shaft faces the positioning keyway structure of the rotor core, and the angle is fixed by the positioning key.

[0021] Preferably, in step S4, there is a second method for fixing the flattened part of the motor rotating shaft to face the center of the magnetic pole. The rotor core does not have a positioning keyway structure, and a jig is designed to locate the flattened part of the rotor core and the motor rotating shaft. The rotor core and the motor rotating shaft are respectively installed in the jig, and the motor rotating shaft and the rotor core can be fixed by glue or interference fit.

[0022] Preferably, the flat position of the motor rotating shaft is aligned with the N pole or S pole position of the magnetic steel.

[0023] Compared with the prior art, the method of using the cogging torque to locate the angle of the rotating shaft of the motor can realize that when the motor winding is not powered on, the motor's own positioning torque, i.e. the cogging torque, is used to lock the position of the rotating shaft, so that the motor's rotating shaft can be fixed at several specified positions according to the design requirements, thereby meeting the product design requirements, reducing the complexity of the structure and the difficulty of the software control algorithm, and achieving cost reduction and efficiency improvement, and improving the market competitiveness of the product.

Brief Description of the Drawings

[0024] Figure 1 A three-dimensional view of a die head of the method for positioning the flat angle of the motor rotating shaft by using the cogging torque of the present invention;

[0025] Figure 2 It is an axial view of the die head of the method for positioning the flat angle of the motor rotating shaft by using the cogging torque of the present invention;

[0026] Figure 3 It is a stereoscopic diagram of the assembly of the stator core and the die head of the method for positioning the flat position angle of the motor rotating shaft by using the cogging torque of the present invention;

[0027] Figure 4 This is an axial view of the assembly of the stator core and the die head of the method for positioning the flat angle of the motor rotating shaft by using the cogging torque of the present invention;

[0028] Figure 5 It is a stereoscopic diagram of the assembly of the housing and the die head of the method for positioning the flat angle of the motor rotating shaft by using the cogging torque of the present invention;

[0029] Figure 6 This is an axial view of the assembly of the housing and the die head of the method for positioning the flat angle of the motor rotating shaft by using the cogging torque of the present invention;

[0030] Figure 7 It is a schematic diagram of the assembly of the motor rotating shaft and the magnetic steel in the method of locating the flat angle of the motor rotating shaft by using the cogging torque of the present invention;

[0031] Figure 8 A schematic diagram of an unstable equilibrium point of the method for positioning the flat angle of the motor rotating shaft by using the cogging torque of the present invention;

[0032] Fig. 9 It is a schematic diagram of a first stable equilibrium state of the method for positioning the flat angle of the rotating shaft of a motor by using the cogging torque of the present invention;

[0033] Fig.10 It is a schematic diagram of a second stable equilibrium state of the method for positioning the flat angle of the rotating shaft of a motor by using the cogging torque of the present invention;

[0034] Fig.11 A cross-sectional view of the motor structure of the method for positioning the flat angle of the motor rotating shaft by using the cogging torque of the present invention. [Specific implementation method]

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] It should be noted that in the embodiments of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are limited to relative positions on the specified view, rather than absolute positions.

[0037] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0038] See also Figures 1 to 11 The method for positioning the flat position angle of the motor rotating shaft by using the cogging torque of the present invention specifically relates to a design method for positioning the flat position of the motor shaft at several specified positions by rotating the motor shaft when the motor winding is not energized, and includes the following steps:

[0039] Step S1, designing and manufacturing a die head 100 with a positioning function.

[0040] In step S1 , the die head 100 is provided with a first key 110 and a second key 120 , and the first key 110 and the second key 120 are distributed at an X angle, where the X angle is the angle between the center line of the stator slot 51 and the center line a of the stator tooth, and is determined by the stator core 5 .

[0041] The number of the first keys 110 is less than or equal to the number of the stator slots 51 in the stator core 5 , and the first keys 110 are evenly distributed on the die head 100 .

[0042] Step S2 , installing the stator core 5 in cooperation with the die head 100 , and positioning the stator core 5 .

[0043] In step S2 , the first key 110 is inserted into the stator tooth slot 51 in the stator core 5 to position the stator core 5 .

[0044] Step S3, the housing 9 is assembled with the die head 100, and the housing 9 and the stator core 5 are positioned at an angle after assembly.

[0045] In step S3, the housing 9 is provided with a positioning notch 91 or other characteristic parts with a positioning function that matches the second key 120, the positioning notch or other characteristic parts with a positioning function are assembled with the second key 120, and then the stator core 5 and the housing 9 are fixed by gluing. The housing 9 is provided with a housing mounting hole 92, and the housing mounting hole 92 corresponds to the positioning notch 91.

[0046] The center line b of the positioning notch 91 coincides with the center line a of the stator tooth.

[0047] Step S4, the motor rotating shaft 8 in the rotor structure is fixed in a flat position facing the center of the magnetic pole.

[0048] In step S4, there are two ways to fix the motor rotating shaft 8 in a flat position and aligned with the magnetic pole center:

[0049] Method 1: The rotor core 7 itself has a positioning keyway structure, and the keyway of the motor rotating shaft 8 is directly opposite to the positioning keyway structure of the rotor core 7, and the angle is fixed by the positioning key;

[0050] Method 2: The rotor core 7 does not have a positioning keyway structure, and a jig is needed to design the flat position of the rotor core 7 and the motor rotating shaft 8. The rotor core 7 and the motor rotating shaft 8 are respectively installed in the jig, and the motor rotating shaft 8 and the rotor core 7 can be fixed by glue or interference fit.

[0051] The flat position of the motor rotating shaft 8 is aligned with the N pole or S pole position of the magnetic steel 6.

[0052] Step S5, assembling all assembled motor components into a finished motor.

[0053] Step S6, after the motor is assembled, rotate the motor shaft 8 one circle without power to the winding, and the motor shaft 8 is locked at 12 positions of 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, 330°, and 360° (0°).

[0054] The method for positioning the flat position angle of the motor rotating shaft by using the cogging torque of the present invention utilizes the positioning torque (cogging torque) of the permanent magnet motor itself, so that the stable balance point of the cogging torque, i.e., the flat position of the rotating shaft, faces the mounting hole or positioning notch of the housing, and the center of a tooth of the stator core 5 corresponds to the mounting hole or positioning notch of the motor housing 9, and the center of the magnetic steel 6 of the rotor assembly corresponds to the flat position of the motor rotating shaft 8. After the motor is assembled, the motor rotating shaft 8 is rotated, and the flat position of the motor rotating shaft 8 is locked at the position where the stator teeth face the magnetic steel, i.e., the flat position of the motor rotating shaft 8 faces the motor mounting hole, thereby locking the flat position of the motor rotating shaft 8 at the specified position.

[0055] The method of using the cogging torque to locate the flat angle of the motor rotating shaft of the present invention is a design method that uses the cogging torque of the permanent magnet motor itself and realizes locking the rotating shaft at a specified position through a specific combination of motor stator, rotor and housing parts.

[0056] See also Figures 8 to 10 The method of positioning the flat angle of the motor rotating shaft by using the cogging torque of the present invention has the following principle:

[0057] When the winding is not powered, the motor has 6 stator teeth, and the rotor is equipped with 4 permanent magnets with NS poles arranged in sequence and in any position. Let the rotor rotate counterclockwise. When the relative position of the rotor is 45° (ie θ=45), the resultant torque of the rotor is zero, and this position is called the balance point.

[0058] Since the rotor always tends to rotate to a position with smaller magnetic resistance and will not remain at the current position, this position is an unstable equilibrium point. Figure 8 As shown in the figure, when θ=45°, it is an unstable equilibrium point. The unstable equilibrium point is characterized by the center line between two adjacent magnetic poles being aligned with the teeth. When the magnetic field axis of the rotor permanent magnet is aligned with the stator teeth, that is, 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, and 330°, the magnetic resistance is minimum.

[0059] There is a circumferential component in the attraction between the permanent magnet and the stator teeth, which produces torque. It changes nonlinearly with the increase of the angle from the reference position. Its maximum value is not at 52.5°, but closer to a certain position of the stator teeth. It becomes zero at 60° or 90°, which is a stable equilibrium point, such as Fig. 9 , 10 As shown, if there is no large external load applied to the shaft, the shaft will remain in this position permanently. When the rotor is disturbed near the stable equilibrium point, in order to reach the position with the minimum magnetic resistance, the rotor tends to be directly opposite the stator teeth. To rotate the rotor through 90°, an external force must be applied. Therefore, it produces a negative torque by convention.

[0060] From the knowledge of electrical machinery, we know that the relationship between the number of cogging torque cycles in a mechanical cycle and the number of slots S and poles P is as follows:

[0061] The number of tooth torque cycles N = LCM (S, P), which is the least common multiple of the number of slots and the number of poles.

[0062] The motor of the present invention is 6S4P, so the number of torque cycles N=LCM(6,4)=12.

[0063] From the above analysis, it can be seen that the stable equilibrium point of the tooth slot torque is when the center line of the magnetic steel is directly opposite to the center line of the stator tooth, that is, the locking position.

[0064] See also Fig.11 The motor of the present invention includes a bearing 1, a gasket 2, a spring 3, a bobbin 4, a stator core 5, a magnetic steel 6, a rotor core 7, a motor rotating shaft 8, a housing 9, a winding 10, a copper sleeve 11, and a rear cover 12.

[0065] The rotor structure is composed of magnetic steel 6, rotor core 7, and motor rotating shaft 8, which respectively provide magnetic flux, magnetic circuit and support functions;

[0066] The bobbin 4 and the stator core 5 are used to fix the winding 10 and provide a magnetic circuit.

[0067] The spring 3 and the washer 2 preload the bearing 1, the copper sleeve 11 axially positions the rotor, and the rear cover 12, the housing 9 and the bearing 1 support the rotor to rotate.

[0068] Compared with the prior art, the method of using tooth slot torque to locate the flat angle of the motor's rotating shaft of the present invention utilizes the motor's own tooth slot positioning torque, and through a series of stator and rotor parts assembly correspondence, can lock the rotating shaft in a specific position when the power is off, thereby meeting customer requirements for the product's rotating shaft flat position locking position; reducing the difficulty of software-driven control of the position and improving positioning accuracy.

[0069] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any modifications, equivalent substitutions and improvements made within the concept of the present invention should be included in the patent protection scope of the present invention.

Claims

1. A method for positioning the flat angle of a motor rotating shaft using cogging torque, characterized in that: The steps include: Step S1, designing and manufacturing a die head with a positioning function; Step S2, installing the stator core and the die head together to position the stator core; Step S3, installing the housing and the die head together, and positioning the angle between the housing and the stator core after assembly; Step S4, the motor rotating shaft in the rotor structure is fixedly aligned with the center of the magnetic pole; Step S5, assembling all assembled motor components into a finished motor; Step S6, after the motor is assembled, rotate the motor shaft one circle without power to the winding, and the motor shaft is locked at 12 positions of 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, and 330° respectively.

2. The method for positioning the flat angle of the motor rotating shaft by using the cogging torque as claimed in claim 1, characterized in that: In the step S1, a first key and a second key are provided on the die head, and the first key and the second key are distributed at an X angle, where the X angle is the angle between the center line of the stator tooth slot and the center line of the stator tooth.

3. The method for positioning the flat angle of the motor rotating shaft by using the cogging torque as claimed in claim 2, characterized in that: The number of the first keys is less than or equal to the number of stator tooth slots in the stator core, and the first keys are evenly distributed on the die head.

4. The method for positioning the flat angle of the motor rotating shaft by using the cogging torque as claimed in claim 1, characterized in that: In the step S2, the first key is inserted into the stator tooth slot in the stator core to position the stator core.

5. The method for positioning the flat angle of the motor rotating shaft by using the cogging torque as claimed in claim 1, characterized in that: In step S3, a positioning notch or other characteristic part with a positioning function matching the second key is provided on the casing, the positioning notch or other characteristic part with a positioning function is assembled with the second key, and then the stator core and the casing are fixed by gluing.

6. The method for positioning the flat angle of the motor rotating shaft by using the cogging torque as claimed in claim 5, characterized in that: The housing is provided with a housing mounting hole, and the housing mounting hole corresponds to the positioning notch.

7. The method for positioning the flat angle of the motor rotating shaft by using the cogging torque as claimed in claim 6, characterized in that: The center line of the positioning notch coincides with the center line of the stator teeth.

8. The method for positioning the flat angle of the motor rotating shaft by using the cogging torque as claimed in claim 1, characterized in that: In step S4, there is a method for fixing the flat position of the motor rotating shaft to face the center of the magnetic pole. The rotor core itself has a positioning keyway structure, and the keyway of the motor rotating shaft faces the positioning keyway structure of the rotor core, and the angle is fixed by the positioning key.

9. The method for positioning the flat angle of the motor rotating shaft by using the cogging torque as claimed in claim 1, characterized in that: In step S4, there is a second method for fixing the flattened part of the motor rotating shaft to face the center of the magnetic pole. The rotor core does not have a positioning keyway structure, and a jig is designed to locate the flattened part of the rotor core and the motor rotating shaft. The rotor core and the motor rotating shaft are respectively installed in the jig, and the motor rotating shaft and the rotor core can be fixed by glue or interference fit.

10. The method for positioning the flat angle of the motor rotating shaft by using the cogging torque as claimed in claim 1, characterized in that: The flat position of the motor rotating shaft is aligned with the N pole or S pole position of the magnetic steel.

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