Brushless motor
The integrated frame design of the brushless motor enhances concentricity accuracy, addressing the issue of decreased performance in conventional motors by integrating the motor and resolver components, resulting in a compact and cost-effective motor with improved 1X axis resolver functionality.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- ICHINOMIYA ELECTRIC
- Filing Date
- 2022-07-14
- Publication Date
- 2026-06-19
AI Technical Summary
Conventional sealed motors with resolvers suffer from decreased concentricity accuracy, leading to increased electrical errors and reduced motor performance, particularly when using a 1X axis multiple angle resolver.
A brushless motor design that integrates the motor stator, resolver stator, and non-load side bearing within a single frame, eliminating the need for a non-load side bracket, thereby enhancing concentricity accuracy and reducing manufacturing costs.
The design achieves high resolver concentricity accuracy, enabling a small, low-cost motor with improved motor performance and convenience for 1X axis multiple angle resolvers.
Smart Images
Figure 0007876186000001 
Figure 0007876186000002 
Figure 0007876186000003
Abstract
Description
Technical Field
[0001] The present invention relates to a sealed brushless motor having a resolver.
Background Art
[0002] A sealed motor in which a load-side bracket and a counter-load-side bracket are joined to both ends of a cylindrical motor frame is widely used. When attaching a resolver to this motor, the resolver is housed in a cover, and the cover is attached to the outside of the counter-load-side bracket. A motor having such a structure is described in, for example, Patent Document 1.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In the above conventional motor, a cover housing the resolver is attached to the outside of the counter-load-side bracket. Therefore, the concentricity of a plurality of components is integrated, and the concentricity accuracy of the resolver decreases. When the concentricity accuracy of the resolver decreases, the electrical error increases and the recognition accuracy of the rotor poles decreases. As a result, the motor torque decreases and the motor performance deteriorates.
[0005] A resolver with an axis multiple angle of 1X has the advantage of high convenience because it can recognize the absolute position within a mechanical angle of 360°. However, when the axis multiple angle is 1X, the motor performance significantly deteriorates as the concentricity accuracy of the resolver decreases compared to the case of other axis multiple angles (for example, 2X). Therefore, in order to put a resolver with an axis multiple angle of 1X into practical use, it is necessary to achieve high concentricity accuracy.
[0006] This invention has been made in view of the above circumstances, and aims to provide a brushless motor that is small, low-cost, and has high resolver concentricity accuracy. [Means for solving the problem]
[0007] (1) The brushless motor of the present invention comprises a shaft, a motor rotor fixed to the shaft, a motor stator located outside the motor rotor and constituting a motor section together with the motor rotor, a resolver rotor rotatable with the shaft, a resolver stator located outside the resolver rotor and constituting a variable reluctance type resolver section together with the resolver rotor, a frame housing the motor section and the resolver section and having an opening on the load side, a load-side bracket having a housing for the load-side bearing of the shaft and being joined to the opening in a sealed state, and a cover. The frame has, in order from the side closest to the opening, a first housing section supporting the motor stator, a second housing section supporting the resolver stator, and a third housing section which is the housing for the non-load-side bearing of the shaft. The cover covers the second housing section and the third housing section and is joined to the first housing section in a sealed state.
[0008] The brushless motor described above does not have a non-load side bracket. Therefore, the brushless motor can be miniaturized and its manufacturing cost can be reduced. Furthermore, the frame integrates the motor stator, resolver stator, and housing of the non-load side bearing. As a result, all machining can be completed without having to change the grip of the frame during machining. Consequently, the concentricity accuracy of the motor and resolver sections is dramatically improved. Thus, a small, low-cost brushless motor with high resolver concentricity accuracy can be provided.
[0009] (2) Preferably, the first surface of the cover may be provided with a motor connection portion for electrically connecting the motor stator to an external circuit and a resolver connection portion for electrically connecting the resolver stator to the external circuit.
[0010] (3) Preferably, the second housing portion may have a plurality of support members that extend in the same direction as the shaft and support the resolver stator at positions spaced apart from each other.
[0011] (4) Preferably, the second housing portion has, as the plurality of support members, a first support member and a second support member connected to the first housing portion and the third housing portion and positioned symmetrically with respect to the shaft when viewed from the direction of extension of the shaft, and a third support member and a fourth support member not connected to the first housing portion but connected to the third housing portion and positioned symmetrically with respect to the shaft when viewed from the direction of extension of the shaft, wherein the minimum distance between the third support member and the first support member and the minimum distance between the third support member and the second support member may be different when viewed from the direction of extension of the shaft.
[0012] (5) Preferably, the axial double angle of the resolver section may be 1X. [Effects of the Invention]
[0013] According to the present invention, it is possible to provide a brushless motor that is small, low-cost, and has high resolver concentricity accuracy. [Brief explanation of the drawing]
[0014] [Figure 1] Figure 1 is a perspective view of a brushless motor 10 according to one embodiment of the present invention. [Figure 2] Figure 2 is a cross-sectional view of the brushless motor 10. [Figure 3] Figure 3(A) is a left side view of the brushless motor 10, and Figure 3(B) is a right side view of the brushless motor 10. [Figure 4] Figure 4 is a perspective view of frame 20, viewed from the same direction as in Figure 1. [Figure 5] Figure 5 is a perspective view of frame 20, viewed from the opposite direction to that shown in Figure 1. [Modes for carrying out the invention]
[0015] The following describes a brushless motor 10 according to one embodiment of the present invention. It goes without saying that the embodiments described below are merely examples of the present invention, and the embodiments of the present invention can be appropriately modified without changing the gist of the present invention. As shown in Figure 1, the brushless motor 10 according to the embodiment has defined vertical direction 7, front-rear direction 8, and left-right direction 9. The right side is also called the load side, and the left side is also called the non-load side. The vertical direction 7, front-rear direction 8, and left-right direction 9 are names given for the convenience of explanation and are unrelated to the installation configuration of the brushless motor 10.
[0016] [Overall configuration of brushless motor 10] As shown in Figures 1 to 3, the brushless motor 10 according to this embodiment includes a shaft 11, a motor rotor 12, a motor stator 13, a resolver rotor 14, a resolver stator 15, a frame 20, a load-side bracket 30, and a cover 40. The brushless motor 10 is a sealed brushless motor having a resolver.
[0017] [Shaft 11] The shaft 11 is the rotation axis of the brushless motor 10. The shaft 11 has a generally cylindrical shape (see Figure 2). The shaft 11 extends in the left-right direction 9 and has four parts with different radii. The shaft 11 is supported by a load-side bearing 18 and an unload-side bearing 19 and is rotatable around the axis extending in the left-right direction 9 (the dashed line shown in Figure 2).
[0018] [Motor rotor 12 and motor stator 13] The motor rotor 12 is formed by providing magnets on a part of the outer peripheral surface of the shaft 11. The outer peripheral surface of the motor rotor 12 is magnetized so that N poles and S poles appear alternately in the rotational direction. The motor rotor 12 is fixed to the shaft 11 and is rotatable together with the shaft 11.
[0019] The motor stator 13 has a cylindrical shape and is located outside the motor rotor 12. The motor stator 13 has a plurality of teeth (not shown), and coils are wound around each tooth. The outer peripheral surface of the motor rotor 12 and the inner peripheral surface of the motor stator 13 face each other with a predetermined interval in the radial direction.
[0020] A three-phase AC voltage is supplied to the motor stator 13 from an external circuit (not shown; hereinafter referred to as the external circuit C) of the brushless motor 10 via the motor connection part 41. When a three-phase AC voltage is supplied to the motor stator 13, the motor rotor 12 and the shaft 11 rotate. Thus, the motor stator 13 constitutes the motor part 16 together with the motor rotor 12. Note that the number of poles and the number of slots of the motor part 16 are arbitrary.
[0021] [Resolver Rotor 14 and Resolver Stator 15] The resolver rotor 14 has a generally cylindrical shape. The shaft 11 is inserted through the resolver rotor 14. The resolver rotor 14 is rotatable together with the shaft 11. The resolver stator 15 has a cylindrical shape and is located outside the resolver rotor 14. The resolver stator 15 has a plurality of teeth (not shown), and coils are wound around each tooth. The outer peripheral surface of the resolver rotor 14 and the inner peripheral surface of the resolver stator 15 face each other with a predetermined interval in the radial direction.
[0022] When the resolver rotor 14 is cut by a plane perpendicular to the left-right direction 9, the outer shape of the cross-section is not a perfect circle, but rather a shape in which parts with a larger radial size and parts with a smaller radial size appear alternately. When the shaft 11 rotates, the resolver rotor 14 also rotates. At this time, the distance between the outer surface of the resolver rotor 14 and the inner surface of the resolver stator 15 changes with the rotation of the resolver rotor 14. The resolver stator 15 is connected to an external circuit C via a resolver connection part 42. The external circuit C detects the position (rotation angle) of the resolver rotor 14 based on the output signal of the resolver stator 15. In this way, the resolver stator 15, together with the resolver rotor 14, constitutes a variable reluctance type resolver section 17. The axis multiplication angle of the resolver section 17 is arbitrary. The axis multiplication angle can be, for example, 1X, 2X, or nX (where n is an integer of 3 or more).
[0023] [Frame 20] As shown in Figure 5, the frame 20 has an opening 28 at the load-side end. As shown in Figure 4, the frame 20 has, in order from the side closest to the opening 28, a first housing portion 21 that supports the motor stator 13, a second housing portion 22 that supports the resolver stator 15, and a third housing portion 23 that is the housing for the non-load-side bearing 19 of the shaft 11. The frame 20 is formed by integrally forming the first housing portion 21, the second housing portion 22, and the third housing portion 23 using a metal material. The frame 20 houses the motor portion 16, the resolver portion 17, and the non-load-side bearing 19.
[0024] When the first housing portion 21 is cut by a plane perpendicular to the left-right direction 9, the outer shape of the cross-section is a rectangle with missing corners in all four directions, and the inner shape is a circle. The first housing portion 21 has a cylindrical internal space. The first housing portion 21 houses the motor portion 16, which includes the motor rotor 12 and the motor stator 13. The diameter of the internal space of the first housing portion 21 is equal to the diameter of the motor stator 13. When the motor stator 13 is housed in the first housing portion 21, the outer surface of the motor stator 13 abuts against the inner surface of the first housing portion 21. In this way, the first housing portion 21 supports the motor stator 13.
[0025] The third housing portion 23 has a cylindrical shape and a cylindrical internal space. The third housing portion 23 houses the non-load side bearing 19 (see Figure 2).
[0026] The second housing section 22 has a first support member 24, a second support member 25, a third support member 26, and a fourth support member 27 (see Figure 4). The first to fourth support members 24 to 27 all extend in the left-right direction 9, that is, in the same direction as the shaft 11.
[0027] As shown in Figure 4, the right end of the first support member 24 is connected to the left end of the front wall of the first housing section 21, near the center in the vertical direction 7. The left end of the first support member 24 is connected to the foremost part of the third housing section 23. The right end of the second support member 25 is connected to the left end of the rear wall of the first housing section 21, near the center in the vertical direction 7. The left end of the second support member 25 is connected to the rearmost part of the third housing section 23.
[0028] The right end of the third support member 26 is not connected to the first housing portion 21. The left end of the third support member 26 is connected to a predetermined position on the third housing portion 23. The right end of the fourth support member 27 is not connected to the first housing portion 21. The left end of the fourth support member 27 is connected to another position on the third housing portion 23.
[0029] When the brushless motor 10 is viewed from the left side, the first support member 24 is located at the 3 o'clock position with respect to the rotation axis of the shaft 11, and is connected to the third housing portion 23 at that position. The second support member 25 is located at the 9 o'clock position with respect to the rotation axis of the shaft 11, and is connected to the third housing portion 23 at that position. The third support member 26 is located approximately 60° counterclockwise from the first support member 24 with respect to the rotation axis of the shaft 11, and is connected to the third housing portion 23 at that position. The fourth support member 27 is located approximately 60° counterclockwise from the second support member 25 with respect to the rotation axis of the shaft 11, and is connected to the third housing portion 23 at that position.
[0030] The first support member 24 and the second support member 25 are positioned symmetrically with respect to the shaft 11 when viewed from the direction of extension of the shaft 11. The third support member 26 and the fourth support member 27 are positioned symmetrically with respect to the shaft 11 when viewed from the direction of extension of the shaft 11. The minimum distance between the third support member 26 and the first support member 24 is different from the minimum distance between the third support member 26 and the second support member 25 when viewed from the direction of extension of the shaft 11. The minimum distance between the fourth support member 27 and the first support member 24 is different from the minimum distance between the fourth support member 27 and the second support member 25 when viewed from the direction of extension of the shaft 11.
[0031] The third support member 26 has a bolt hole 51 on its left end face. The fourth support member 27 has a bolt hole 52 on its left end side. The resolver stator 15 has mounting portions (not shown) with bolt holes at positions corresponding to the third support member 26 and the fourth support member 27. After the resolver portion 17 is housed in the second housing portion 22, a bolt 55 is inserted into the bolt hole 51 and a bolt 56 is inserted into the bolt hole 52 (see Figure 1). Bolts 55 and 56 are also inserted into the bolt holes of the mounting portion of the resolver stator 15. In this way, the resolver portion 17 is attached to the second housing portion 22.
[0032] On the right-hand portions of the first to fourth support members 24 to 27, the curvature of the inner surface is the same as the curvature of the outer surface of the resolver stator 15. When the resolver section 17 is housed in the second housing section 22, the outer surface of the resolver stator 15 abuts against the inner surface of the right-hand portions of the first to fourth support members 24 to 27. As a result, the first to fourth support members 24 to 27 support the resolver stator 15 at positions spaced apart from each other. The second housing section 22 supports the resolver stator 15 and houses the resolver section 17, which includes the resolver rotor 14 and the resolver stator 15.
[0033] [Load-side bracket 30] The load-side bracket 30 covers the load-side side (right side) of the first housing portion 21. The load-side bracket 30 has a housing 31 for the load-side bearing 18 of the shaft 11. The housing 31 has a cylindrical internal space. The housing 31 accommodates the load-side bearing 18 (see Figure 2).
[0034] The load-side surface of the first housing section 21 has four bolt holes 53 (see Figure 5). The load-side bracket 30 has four bolt holes (not shown) in positions corresponding to the four bolt holes 53. When attaching the load-side bracket 30 to the frame 20, a bolt 57 is inserted into each bolt hole of the load-side bracket 30 (see Figure 3(B)). The bolts 57 inserted into the bolt holes of the load-side bracket 30 are also inserted into the bolt holes 53 of the first housing section 21. In this way, the load-side bracket 30 is attached to the load-side surface of the first housing section 21.
[0035] An O-ring 61 is located on the inner circumferential surface near the opening 28 of the first housing portion 21 (see Figure 2). The O-ring 61 prevents foreign matter from entering the inside of the brushless motor 10 from the outside after the load-side bracket 30 is attached to the first housing portion 21. In this way, the load-side bracket 30 is joined to the opening 28 in a sealed state.
[0036] [Cover 40] The cover 40 has a box-like shape and an opening on the load side (right side). The cover 40 is made of, for example, a metal material or a plastic material. Figure 1 shows the case where the cover 40 is made of a transparent plastic material in order to facilitate understanding of the invention.
[0037] The dimensions of cover 40 in the vertical direction 7 and the front-to-back direction 8 are equivalent to the dimensions of the first housing portion 21 in the vertical direction 7 and the front-to-back direction 8. The dimensions of cover 40 in the left-to-right direction 9 are larger than the dimensions of the second housing portion 22. Cover 40 covers the second housing portion 22 and the third housing portion 23.
[0038] When the cover 40 is cut by a plane perpendicular to the left-right direction 9, the outer and inner shapes of the cross-section are rectangles with notches at the four corners. The non-load side (left side) of the first housing portion 21 has bolt holes 54 in the front lower portion and the rear upper portion (see Figure 4). The cover 40 has a mounting portion 43 with bolt holes (not shown) at positions corresponding to the bolt holes 54. When attaching the cover 40 to the frame 20, bolts 58 are inserted into the bolt holes of the mounting portion 43 of the cover 40 (see Figure 3(A)). The bolts 58 inserted into the bolt holes of the mounting portion 43 of the cover 40 are also inserted into the bolt holes 54 of the first housing portion 21. In this way, the cover 40 is attached to the non-load side of the first housing portion 21.
[0039] A sealing member 62 is located on the inner circumferential surface near the opening of the cover 40. The sealing member 62 prevents foreign matter from entering the inside of the brushless motor 10 from the outside after the cover 40 has been attached to the frame 20. In this way, the cover 40 is joined to the first housing portion 21 in a sealed state.
[0040] On the upper surface of the cover 40 (an example of the first surface), there is a motor connection part 41 and a resolver connection part 42. The motor connection part 41 is for electrically connecting the motor stator 13 to the external circuit C. The resolver connection part 42 is for electrically connecting the resolver stator 15 to the external circuit C.
[0041] For example, the motor connection section 41 may have connectors on both the inside and outside of the cover 40. Wiring connected to the motor stator 13 is inserted into the connector on the inside of the cover 40. Wiring connected to the external circuit C is inserted into the connector on the outside of the cover 40. The motor connection section 41 electrically connects the two connectors.
[0042] The resolver connection section 42 may have connectors on both the inside and outside of the cover 40. Wiring connected to the resolver stator 15 is inserted into the connector on the inside of the cover 40. Wiring connected to the external circuit C is inserted into the connector on the outside of the cover 40. The resolver connection section 42 electrically connects the two connectors.
[0043] Alternatively, the motor connection section 41 may not have a connector and may allow the wiring connected to the motor stator 13 to pass through directly. The resolver connection section 42 may also not have a connector and may allow the wiring connected to the resolver stator 15 to pass through directly. In this case, the wiring that has passed through the motor connection section 41 or the resolver connection section 42 is connected to the external circuit C.
[0044] [Effects and Effects] As described above, in the brushless motor 10 according to this embodiment, the frame 20 has, in order from the side closest to the opening 28, a first housing portion 21 that supports the motor stator 13, a second housing portion 22 that supports the resolver stator 15, and a third housing portion 23 which is the housing for the non-load side bearing 19 of the shaft 11. The cover 40 covers the second housing portion 22 and the third housing portion 23 and is joined to the first housing portion 21 in a sealed state.
[0045] The brushless motor 10 does not have a non-load side bracket. Therefore, the brushless motor 10 can be made smaller and its manufacturing cost can be reduced. In addition, the frame 20 integrates the housing of the motor stator 13, resolver stator 15, and non-load side bearing 19. Therefore, when machining, all machining can be completed without changing the grip of the frame 20. Consequently, the concentricity accuracy of the motor section 16 and resolver section 17 is dramatically improved. Thus, a small, low-cost brushless motor with high resolver concentricity accuracy can be provided.
[0046] In the brushless motor 10, a motor connection part 41 for electrically connecting the motor stator 13 to the external circuit C and a resolver connection part 42 for electrically connecting the resolver stator 15 to the external circuit C are located on the upper surface of the cover 40. As a result, the wiring connected to the motor stator 13 and the wiring connected to the resolver stator 15 can be easily taken out from inside the brushless motor 10, greatly improving the work efficiency when assembling the brushless motor 10.
[0047] The second housing section 22 extends in the same direction as the shaft 11 and has first to fourth support members 24 to 27 that support the resolver stator 15 at positions spaced apart from each other. The first support member 24 and the second support member 25 are connected to the first housing section 21 and the third housing section 23 and are positioned symmetrically with respect to the shaft 11 when viewed from the direction of extension of the shaft 11. The third support member 26 and the fourth support member 27 are not connected to the first housing section 21 but are connected to the third housing section 23 and are positioned symmetrically with respect to the shaft 11 when viewed from the direction of extension of the shaft 11. When viewed from the direction of extension of the shaft 11, the minimum distance between the third support member 26 and the first support member 24 is different from the minimum distance between the third support member 26 and the second support member 25. The frame 20 has the second housing section 22 configured as described above. Therefore, the resolver unit 17 can be easily housed in the second housing unit 22, improving work efficiency during the assembly of the brushless motor 10.
[0048] The axial angle multiplication of the resolver unit 17 may be 1X. In the brushless motor 10, the concentricity accuracy of the resolver unit 17 is high, so the absolute position within the 360° mechanical angle can be recognized, and a resolver unit 17 with an axial angle multiplication of 1X, which is highly convenient, can be realized.
[0049] [Differentiation] Although embodiments of the present invention have been described in detail above, the above description is merely illustrative in all respects of the present invention. Needless to say, various improvements and modifications can be made without departing from the scope of the present invention. With respect to each component of the brushless motor 10 according to the above embodiment, components may be omitted, replaced, or added as appropriate depending on the embodiment. Furthermore, the shape and size of each component of the brushless motor 10 may also be set as appropriate depending on the embodiment. [Explanation of Symbols]
[0050] 10. Brushless motor 11... Shaft 12. Motor Rotor 13. Motor stator 14.. Resolver Rota 15. Resolver Statita 16. Motor section 17. Resolver section 18. Load-side bearing 19. Non-load side bearing 20...frames 21. Housing Department 1 22.. Second Housing Department 23. Third Housing Department 24. First support member 25...Second support member 26. Third support member 27. Fourth support member 28...Aperture 30... Load-side bracket 31. Housing 40...cover 41...Motor connection part 42. Connector for resolver
Claims
1. The shaft and A motor rotor fixed to the shaft mentioned above, A motor stator is located on the outside of the motor rotor and, together with the motor rotor, constitutes the motor section. A resolver rotor that can rotate together with the above shaft, A resolver stator, located outside the resolver rotor and together with the resolver rotor, constitutes a variable reluctance type resolver section. A frame housing the motor section and the resolver section, having an opening on the load side, The load-side bracket has a housing for the load-side bearing of the above shaft and is joined to the opening in a sealed state, Equipped with a cover, The above frame is arranged in order from the side closest to the opening: The first housing portion supporting the motor stator, The second housing section supporting the resolver stator, It has a third housing portion which is the housing of the non-load side bearing of the shaft, The above cover covers the second housing portion and the third housing portion and is joined to the first housing portion in a sealed state, forming a brushless motor.
2. The brushless motor according to claim 1, wherein a motor connection portion for electrically connecting the motor stator to an external circuit and a resolver connection portion for electrically connecting the resolver stator to the external circuit are located on the outer surface of the cover.
3. The brushless motor according to claim 2, wherein the second housing portion extends in the same direction as the shaft and has a plurality of support members that support the resolver stator at positions spaced apart from each other.
4. The above-mentioned second housing portion consists of the above-mentioned plurality of support members, A first support member and a second support member are connected to the first housing portion and the third housing portion, and are positioned symmetrically with respect to the shaft when viewed from the direction of extension of the shaft. It has a third support member and a fourth support member that are not connected to the first housing portion but are connected to the third housing portion and are located symmetrically with respect to the shaft when viewed from the direction of extension of the shaft, The brushless motor according to claim 3, wherein, when viewed from the direction of extension of the shaft, the minimum distance between the third support member and the first support member is different from the minimum distance between the third support member and the second support member.
5. The brushless motor according to any one of claims 1 to 3, wherein the axial double angle of the resolver section is 1X.