Motor and method for manufacturing the same

Abstract

To firmly fix a magnet and a shaft.SOLUTION: A motor includes: a cylindrical magnet 41 having an inner peripheral surface 41a; a shaft 42 having an intermediate portion 43 including an outer peripheral surface 43a facing the inner peripheral surface 41a, a first extension portion 44 extending from the intermediate portion 43 to one side, and a second extension portion 45 extending from the intermediate portion 43 to the other side; and an adhesive portion 51 provided at least between the inner peripheral surface 41a and the outer peripheral surface 43a and fixing the magnet 41 and the shaft 42. The shaft 42 has a first opening portion 47 provided in the first extending portion 44, a second opening portion 48 provided in the intermediate portion 43 and opening to the outer peripheral surface 43a, and a communication path 49 that allows the first opening portion 47 and the second opening portion 48 to communicate with each other.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a motor and a method for manufacturing a motor. [Background technology]

[0002] Conventionally, motors equipped with a rotor having a magnet and a shaft bonded together are known (for example, Patent Document 1). Patent Document 1 discloses "a brushless motor rotor formed by bonding a plurality of cylindrical magnets and a shaft, characterized in that one side of the inner diameter portion is chamfered and the other is not chamfered, and the chamfered portions on one side are arranged adjacent to each other, and a groove is formed on the outer circumferential surface of the shaft that contacts the inner diameter of the cylindrical magnet." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-164084 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are cases where the amount of adhesive applied to the magnet and shaft is insufficient due to air getting between them. If the amount of adhesive applied is insufficient, problems such as the magnet spinning freely when the motor is running can occur. In such a situation, one of the objectives of the present disclosure is to firmly fix the magnet and shaft. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a motor including a cylindrical magnet having an inner circumferential surface, a shaft having a middle portion including an outer circumferential surface facing the inner circumferential surface, a first extending portion extending in one direction from the middle portion, and a second extending portion extending in the other direction from the middle portion, and an adhesive portion provided between at least the inner circumferential surface and the outer circumferential surface to secure the magnet to the shaft, the shaft having a first opening provided in the first extending portion, a second opening provided in the middle portion and opening to the outer circumferential surface, and a communication passage providing communication between the first opening and the second opening.

[0006] Another aspect of the present disclosure relates to a method for manufacturing the motor described above, the method including: a preparation step of preparing the magnet and the shaft; an insertion step of inserting the shaft into the magnet so that the inner circumferential surface faces the outer circumferential surface; an injection step of injecting an adhesive between the inner circumferential surface and the outer circumferential surface from the first opening through the communication passage and the second opening; and a solidification step of solidifying the adhesive to form the adhesive joint. [Effects of the Invention]

[0007] According to the present disclosure, the magnet and the shaft can be firmly fixed together. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a motor according to the present disclosure. [Figure 2] FIG. 2 is a plan view showing the configuration of the shaft. [Figure 3] 1A and 1B are diagrams showing the configuration of a rotor, in which (a) is a plan view and (b) is a side cross-sectional view taken along line BB. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes exemplary embodiments of a motor and a method for manufacturing a motor according to the present disclosure. However, the present disclosure is not limited to the examples described below. While the following description may use specific numerical values ​​and materials, other numerical values ​​and materials may be used as long as the effects of the present disclosure are achieved.

[0010] (Motor) A motor according to the present disclosure includes a magnet, a shaft, and an adhesive portion. These components form a rotor of the motor according to the present disclosure. The motor according to the present disclosure may further include a stator disposed opposite the rotor. The stator may have a back yoke portion, a plurality of teeth extending radially inward from the back yoke portion, and coils wound around the plurality of teeth.

[0011] The magnet is formed in a cylindrical shape having an inner peripheral surface. The magnet may be formed in a cylindrical shape. The magnet may be radially magnetized and may have, for example, four poles. The magnet may or may not contain a rare earth element. The number of magnets is not particularly limited and may be, for example, one or more and four or less.

[0012] The shaft has an intermediate portion, a first extension portion, and a second extension portion. The intermediate portion, the first extension portion, and the second extension portion may be integrally formed with one another. The shaft may be made of a magnetic material (e.g., stainless steel). The intermediate portion has an outer peripheral surface facing the inner peripheral surface of the magnet. The intermediate portion may be formed in a cylindrical shape. The diameter of the intermediate portion may be, for example, 3 mm or more and 7 mm or less. The first extension portion extends in one direction from the intermediate portion. The first extension portion may be formed in a cylindrical shape. The first extension portion may not be covered by the magnet. The second extension portion extends in the other direction from the intermediate portion. The second extension portion may be formed in a cylindrical shape. The second extension portion may not be covered by the magnet.

[0013] The adhesive portion is provided at least between the inner circumferential surface of the magnet and the outer circumferential surface of the shaft. The adhesive portion fixes the magnet and the shaft. The adhesive portion may be formed by solidifying an adhesive. The adhesive may be, for example, an anaerobic adhesive.

[0014] The shaft has a first opening, a second opening, and a communication passage. The first opening is provided in the first extension portion. The first opening may be open to an end face of the first extension portion or may be open to the outer peripheral surface of the first extension portion. The second opening is provided in the intermediate portion and opens to the outer peripheral surface thereof. The number of second openings is not particularly limited. When multiple second openings are provided, the multiple second openings may be aligned in the circumferential direction of the shaft or in the axial direction of the shaft. The communication passage connects the first opening and the second opening. The communication passage may be formed inside the shaft (more specifically, inside the first extension portion and the intermediate portion).

[0015] In a motor having the above configuration, after inserting the shaft into the magnet, adhesive can be injected through the first opening and allowed to solidify to form a bonded joint. The adhesive injected through the first opening passes through the connecting passage and reaches the gap between the inner circumferential surface of the magnet and the outer circumferential surface of the shaft through the second opening, where it solidifies. This manufacturing method prevents air from entering between the inner circumferential surface of the magnet and the outer circumferential surface of the shaft, ensuring a sufficient amount of adhesive is applied to the magnet and shaft. The bonded joint formed by allowing a sufficient amount of adhesive to solidify firmly secures the magnet and shaft.

[0016] The first extension portion may have an end surface that extends intersecting the central axis of the shaft. The first opening may open to the end surface. In this case, a communication passage extending along the central axis of the shaft can be easily formed. Furthermore, such a communication passage can suppress eccentricity when the shaft rotates. The end surface of the first extension portion may extend perpendicular to the central axis of the shaft.

[0017] Grooves may be formed on the outer peripheral surface. The adhesive may fill at least a portion of the groove. This configuration allows the adhesive to spread more widely along the grooves than when no grooves are formed on the outer peripheral surface, thereby more firmly fixing the magnet and shaft. The shape of the groove is not particularly limited, and may be formed, for example, in a spiral or linear shape. The groove may be formed on at least a portion of the outer peripheral surface, but preferably, it may be formed over 50% to 100% of the outer peripheral surface in the axial direction of the shaft. The adhesive may fill at least a portion of the groove, but preferably, it may fill 70% to 100% of the groove. The width of the groove may be, for example, 0.2 mm to 0.4 mm. The number of grooves is not particularly limited, and may be, for example, two to four.

[0018] The groove may be formed in a spiral shape on the outer peripheral surface. In this case, the groove can be easily formed by turning, and the adhesive can be easily spread over the entire outer peripheral surface. The pitch of the grooves in the axial direction of the shaft may be, for example, 0.5 mm or more and 2 mm or less. When multiple spiral grooves are provided, the same number of second openings as the grooves may be provided, and in this case, the multiple grooves and the multiple second openings may correspond one-to-one. For example, two grooves and two second openings may be provided, and in this case, the two spiral grooves may be arranged in a double spiral shape.

[0019] The second opening may be in communication with the groove. With this configuration, the adhesive flowing out of the second opening can smoothly flow into the groove. In this specification, "the second opening and the groove are in communication" means that the second opening and the groove are in communication with each other so that the adhesive flowing out of the second opening flows directly into the groove. The second opening does not have to be in communication with the groove, but even in this case, it is desirable that the adhesive flowing out of the second opening flows into the groove.

[0020] The groove may extend from the outer peripheral surface of the intermediate portion to the second extending portion. In this case, the portion of the groove formed in the second extending portion (hereinafter referred to as the exposed portion) is not covered by the magnet, so when the adhesive is injected from the first opening, it can be determined from the appearance that the injection of a necessary and sufficient amount of adhesive has been completed by the adhesive reaching the exposed portion.

[0021] The adhesive may also fill at least a portion of the groove formed in the second extension (exposed portion). In this case, the first opening and the exposed portion are located on either side of the adhesive region between the magnet and the shaft (i.e., the region where the inner circumferential surface of the magnet faces the outer circumferential surface of the middle part of the shaft), and it can be easily determined from the appearance that the adhesive injected from the first opening has reached the exposed portion (i.e., that a necessary and sufficient amount of adhesive has been applied).

[0022] (Motor manufacturing method) A motor manufacturing method according to the present disclosure is a method for manufacturing the motor described above. The motor manufacturing method according to the present disclosure includes a preparation step, an insertion step, an injection step, and a solidification step.

[0023] In the preparation step, a magnet and a shaft are prepared. In this specification, preparing an element includes at least both manufacturing the element and bringing in the completed element.

[0024] In the insertion step, the shaft is inserted into the magnet so that the inner peripheral surface of the magnet faces the outer peripheral surface of the intermediate portion of the shaft. In the motor manufacturing method according to the present disclosure, the shaft is preferably inserted into the magnet without applying adhesive to the magnet and the shaft.

[0025] In the injection process, adhesive is injected from the first opening through the communication passage and the second opening between the inner peripheral surface of the magnet and the outer peripheral surface of the intermediate portion of the shaft. This injection method allows a sufficient amount of adhesive to be injected while preventing air from entering between the inner peripheral surface of the magnet and the outer peripheral surface of the intermediate portion of the shaft. The orientation of the magnet and shaft in the injection process is not particularly limited. The adhesive may be, for example, an anaerobic adhesive.

[0026] In the curing step, the adhesive is cured to form an adhesive joint. This allows the magnet and shaft to be firmly fixed. The orientation of the magnet and shaft in the curing step is not particularly limited, but it is preferable to hold the shaft with the first opening facing downwards, for example.

[0027] The injection step may be performed with the second opening positioned above the first opening. In this case, even if air gets into the adhesive, the air rises due to buoyancy inside the adhesive and escapes through the second opening. This further prevents air from getting into the bonded joint obtained by solidifying the adhesive.

[0028] The injection step may be performed with the shaft held substantially upright, which makes it easier to hold the shaft. Here, "substantially upright" means not only that the central axis of the shaft is exactly aligned with the vertical axis, but also that the central axis intersects the vertical axis at an angle of 5° or less.

[0029] As described above, according to the present disclosure, by using a shaft having a first opening, a second opening, and a communication passage, the magnet and shaft can be firmly fixed. Furthermore, according to the present disclosure, it is possible to easily determine from the appearance of the magnet and shaft whether the adhesive has been sufficiently injected or applied.

[0030] An example of a motor and a method for manufacturing a motor according to the present disclosure will be described in detail below with reference to the drawings. The components and steps described above can be applied to the components and steps of the example motor and method for manufacturing a motor described below. The components and steps of the example motor and method for manufacturing a motor described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiment. Of the components and steps of the example motor and method for manufacturing a motor described below, components and steps that are not essential to the motor and method for manufacturing a motor according to the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the shapes and numbers of actual components.

[0031] (Motor) As shown in FIGS. 1 to 3, the motor 10 of this embodiment includes a housing 20, a stator 30, and a rotor 40.

[0032] The housing 20 is configured in a hollow cylindrical shape and accommodates the stator 30 and the rotor 40. The housing 20 has a cylindrical main body 21, a first cover 22 attached to one end (the right end in FIG. 1 ) of the main body 21, and a second cover 23 attached to the other end (the left end in FIG. 1 ) of the main body 21. A first bearing 61 and a second bearing 62 are attached to the first cover 22 and the second cover 23, respectively, and a shaft 42 (described below) of the rotor 40 is rotatably supported by the first bearing 61 and the second bearing 62. The housing 20 may be made of a non-magnetic material (e.g., resin).

[0033] The stator 30 is fixed to the inner wall of the housing 20. The stator 30 has a stator core 31 including a back yoke portion and a plurality of teeth, and a coil 32 wound around the stator core 31. The stator core 31 is formed, for example, by laminating a plurality of electromagnetic steel plates, but is not limited to this. A lead wire 72 is electrically connected to the coil 32 via a conductive member 71 or the like. When a current (e.g., a three-phase AC) is supplied to the coil 32 via the lead wire 72, the rotor 40 rotates around the central axis O.

[0034] The rotor 40 includes a magnet 41, a shaft 42, and an adhesive part 51 (enlarged view of FIG. 3(b)).

[0035] The magnet 41 is formed in a cylindrical shape having an inner peripheral surface 41a. In this embodiment, two magnets 41 are provided, and these are attached to the shaft 42 adjacent to each other in the axial direction. Each magnet 41 is a sintered magnet containing a rare earth element, but is not limited to this.

[0036] The shaft 42 has an intermediate portion 43, a first extending portion 44, and a second extending portion 45. The intermediate portion 43, the first extending portion 44, and the second extending portion 45 are integrally formed with one another and each have a cylindrical shape. Note that the term "intermediate portion 43" refers only to the portion of the shaft 42 covered by the magnet 41. The intermediate portion 43 has an outer peripheral surface 43a that faces the inner peripheral surface 41a of the magnet 41. The first extending portion 44 extends from the intermediate portion 43 in one axial direction (to the right in FIG. 1). The first extending portion 44 has an end surface 44a that extends intersecting (perpendicular in this example) the central axis O of the shaft 42. The first extending portion 44 has a large diameter portion 44b that can contribute to positioning the magnet 41 when attaching the magnet 41 to the shaft 42. The second extending portion 45 extends from the intermediate portion 43 in the other axial direction (to the left in FIG. 1).

[0037] A spiral groove 46 is formed on the outer peripheral surface 43a of the intermediate portion 43, and this groove 46 extends from the outer peripheral surface 43a of the intermediate portion 43 to the second extending portion 45. In other words, the groove 46 is formed across the outer peripheral surface 43a of the intermediate portion 43 that is covered by the magnet 41 and the outer peripheral surface of the second extending portion 45 that is not covered by the magnet 41.

[0038] The shaft 42 has a first opening 47, a second opening 48, and a communication passage 49. The first opening 47 is provided in the first extending portion 44 and opens to an end surface 44a of the first extending portion 44. The second opening 48 is provided in the intermediate portion 43 (more specifically, in a region of the intermediate portion 43 near the large diameter portion 44b) and opens to an outer circumferential surface 43a of the intermediate portion 43. The second opening 48 communicates with an end of the spiral groove 46. As shown in FIG. 3(b), in this embodiment, two second openings 48 are provided side by side in the radial direction. The two second openings 48 are arranged rotationally symmetrically with respect to the central axis O. The communication passage 49 extends inside the shaft 42 along the central axis O and connects the first opening 47 to each second opening 48.

[0039] As shown in FIG. 3(b), the adhesive portion 51 is provided at least between the inner circumferential surface 41a of the magnet 41 and the outer circumferential surface 43a of the intermediate portion 43, and fixes the magnet 41 to the shaft 42. The adhesive portion 51 fills at least a portion of the spiral groove 46. The adhesive portion 51 fills substantially the entire portion of the spiral groove 46 that corresponds to the intermediate portion 43, and a portion of the portion of the groove 46 that is formed in the second extension portion 45. The adhesive portion 51 may also fill an area that does not contribute to fixing the magnet 41 to the shaft 42 (for example, the inside of the communication passage 49). The adhesive portion 51 is made of a solidified anaerobic adhesive, but is not limited to this.

[0040] (Motor manufacturing method) Next, a description will be given of a method for manufacturing the above-described motor 10 (more specifically, the rotor 40 included in the motor 10). The method for manufacturing the motor includes a preparation step, an insertion step, an injection step, and a solidification step.

[0041] In the preparation step, the magnet 41 and the shaft 42 are prepared.

[0042] In the insertion step, the shaft is inserted into the magnet 41 (or the magnet 41 is attached to the shaft ) so that the inner peripheral surface 41a of the magnet 41 and the outer peripheral surface 43a of the intermediate portion 43 of the shaft face each other.

[0043] In the injection step, adhesive (not shown) is injected between the inner circumferential surface 41a of the magnet 41 and the outer circumferential surface 43a of the intermediate portion 43 of the shaft 42 from the first opening 47 through the communicating passage 49, the second opening 48, and the spiral groove 46. This injection step is preferably performed with the second opening 48 positioned higher than the first opening 47, and more preferably with the second opening 48 positioned higher than the first opening 47 and the shaft 42 held substantially upright. In the latter case, in the injection step, the adhesive is preferably injected until it overflows from between the magnet 41 and the shaft 42.

[0044] In the curing step, the adhesive is cured to form the adhesive portion 51. In this curing step, it is preferable to maintain the magnet 41 and the shaft 42 in the same positions as those in the injection step.

[0045] <<Notes>> The above description of the embodiments discloses the following techniques. (Technology 1) a cylindrical magnet having an inner circumferential surface; a shaft having a middle portion including an outer circumferential surface facing the inner circumferential surface, a first extending portion extending in one direction from the middle portion, and a second extending portion extending in the other direction from the middle portion; an adhesive portion provided at least between the inner circumferential surface and the outer circumferential surface and fixing the magnet and the shaft; Equipped with The shaft a first opening provided in the first extension portion; a second opening provided in the intermediate portion and opening to the outer circumferential surface; a communication passage that connects the first opening and the second opening; A motor having (Technology 2) the first extension portion has an end surface that extends intersecting with the central axis of the shaft, The motor according to technique 1, wherein the first opening is open to the end surface. (Technology 3) A groove is formed on the outer circumferential surface, The motor according to Technology 1 or 2, wherein the adhesive portion fills at least a portion of the groove. (Technology 4) The motor according to technique 3, wherein the groove is formed in a spiral shape on the outer circumferential surface. (Technology 5) The motor according to technique 3 or 4, wherein the second opening is in communication with the groove. (Technology 6) The motor according to any one of techniques 3 to 5, wherein the groove extends from the outer circumferential surface of the intermediate portion to the second extending portion. (Technology 7) The motor according to technique 6, wherein the adhesive portion also fills at least a part of the groove formed in the second extension portion. (Technology 8) A method for manufacturing the motor according to any one of techniques 1 to 7, a preparation step of preparing the magnet and the shaft; an insertion step of inserting the shaft into the magnet so that the inner peripheral surface and the outer peripheral surface face each other; an injection step of injecting an adhesive between the inner circumferential surface and the outer circumferential surface from the first opening through the communication passage and the second opening; a solidification step of solidifying the adhesive to form the adhesive portion; A method for manufacturing a motor comprising the steps of: (Technology 9) The motor manufacturing method according to technique 8, wherein the injection step is performed in a state where the second opening is positioned above the first opening. (Technology 10) The method for manufacturing a motor according to technology 9, wherein the injection step is carried out with the shaft in a substantially upright position. [Industrial Applicability]

[0046] The present disclosure can be used in a motor and a method for manufacturing a motor. [Explanation of symbols]

[0047] 10: Motor 20: Housing 21: Main body 22: First cover 23: Second cover 30: Stator 31: Stator core 32: Coil 40:Rotor 41: Magnet 41a: Inner surface 42: Shaft 43: Middle part 43a: Outer surface 44:First extension part 44a: End face 44b: Large diameter section 45:Second extension part 46: Groove 47: First opening 48: Second opening 49:Communication path 51: Adhesive part 61: First bearing 62: Second bearing 71: Conductive material 72: Lead wire O: Central axis

Claims

1. a cylindrical magnet having an inner circumferential surface; a shaft having a middle portion including an outer circumferential surface facing the inner circumferential surface, a first extending portion extending in one direction from the middle portion, and a second extending portion extending in the other direction from the middle portion; an adhesive portion provided at least between the inner circumferential surface and the outer circumferential surface and fixing the magnet and the shaft; Equipped with The shaft a first opening provided in the first extension portion; a second opening provided in the intermediate portion and opening to the outer circumferential surface; a communication passage that connects the first opening and the second opening; A motor having

2. the first extension portion has an end surface extending intersecting the central axis of the shaft, The motor according to claim 1 , wherein the first opening is open to the end surface.

3. A groove is formed on the outer circumferential surface, The motor according to claim 1 , wherein the adhesive fills at least a portion of the groove.

4. The motor according to claim 3 , wherein the groove is formed in a spiral shape on the outer circumferential surface.

5. The motor according to claim 3 , wherein the second opening communicates with the groove.

6. The motor according to claim 3 , wherein the groove extends from the outer circumferential surface of the intermediate portion to the second extending portion.

7. The motor according to claim 6 , wherein the adhesive portion also fills at least a portion of the groove formed in the second extension portion.

8. A method for manufacturing the motor according to claim 1 or 2, comprising the steps of: a preparation step of preparing the magnet and the shaft; an insertion step of inserting the shaft into the magnet so that the inner peripheral surface and the outer peripheral surface face each other; an injection step of injecting an adhesive between the inner circumferential surface and the outer circumferential surface from the first opening through the communication passage and the second opening; a solidification step of solidifying the adhesive to form the adhesive portion; A method for manufacturing a motor comprising the steps of:

9. The motor manufacturing method according to claim 8 , wherein the injection step is performed in a state where the second opening is located above the first opening.

10. The method for manufacturing a motor according to claim 9 , wherein the injection step is performed with the shaft in a substantially upright position.

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