Motor and rotor fixing structure

Abstract

To provide a motor and a rotor fixing structure capable of preventing radial separation between a rotor and a housing.SOLUTION: A motor comprises a rotor and a housing that accommodates the rotor. The housing has a plurality of inner circumferential engagement portions on the inner circumferential surface, and the rotor has a plurality of outer circumferential engagement portions on the outer circumferential surface. The rotor is fixed to the housing by the outer circumferential engagement portions engaging with the inner circumferential engagement portions in a radial direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a motor and a rotor fixing structure. [Background technology]

[0002] There is an outer rotor type motor in which a stator is disposed inside and a rotor is disposed around the stator.

[0003] In addition, Patent Document 1 describes, with regard to motors, "an outer rotor structure of a rotating electric machine in a transaxle having two rotating electric machines and a gear reduction mechanism arranged on multiple shafts, the outer rotor structure comprising: a shaft mounting portion for mounting a rotor shaft extending in the axial direction; a disc portion extending radially from the shaft mounting portion toward the outer periphery; and a ring portion protruding in an annular shape in the axial direction from the outer periphery of the disc portion and having a recess for arranging a rotor core on its inner periphery; a rotor core arranged in the recess for arranging the rotor core in the ring portion and having an annular shape with a predetermined number of magnetic poles provided in the circumferential direction; and a spline provided on the outer periphery of the ring portion for engagement with the gear reduction mechanism" (see claim 1 of Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-164370 Summary of the Invention [Problem to be solved by the invention]

[0005] In outer rotor motors, the rotor is generally fixed to the inner circumferential surface of the housing by press fitting or shrink fitting. However, if a large external force is applied, the rotor and housing, which are supposed to be fixed together, may separate in the radial direction, causing problems such as increased wear and noise.

[0006] The above-mentioned Patent Document 1 does not describe such problems or means for solving them.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a motor and a rotor fixing structure that can prevent radial separation of the rotor and the housing. [Means for solving the problem]

[0008] The present application includes a plurality of means for resolving at least part of the above-described problems, examples of which are as follows: A motor according to one aspect of the present invention that resolves the above-described problems is a motor including a rotor and a housing that houses the rotor, wherein the housing has a plurality of inner peripheral engaging portions on its inner peripheral surface and the rotor has a plurality of outer peripheral engaging portions on its outer peripheral surface, and the rotor is fixed to the housing by radially engaging the outer peripheral engaging portions with the inner peripheral engaging portions.

[0009] A rotor fixing structure according to one aspect of the present invention that solves the above-mentioned problems is a rotor fixing structure for a motor that includes a rotor and a housing that houses the rotor, and has a plurality of inner peripheral engagement portions on the inner peripheral surface of the housing and a plurality of outer peripheral engagement portions on the outer peripheral surface of the rotor, and the rotor is fixed to the housing by radial engagement between the outer peripheral engagement portions and the inner peripheral engagement portions. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a motor and a rotor fixing structure that can prevent the rotor and the housing from being separated in the radial direction.

[0011] Problems, configurations, effects, and the like other than those described above will become clear from the following description of the embodiments. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating an example of a rotor fixing structure of a motor according to a first embodiment. FIG. [Figure 2] 1 is a schematic diagram illustrating an example of a rotor fixing structure of a motor according to a first embodiment. FIG. [Figure 3] FIG. 3 is an enlarged view of part H in FIG. 2. [Figure 4] FIG. 4 is an enlarged view of part K in FIG. 3. [Figure 5] 10A and 10B are diagrams illustrating a motor having a rotor fixing structure different from the rotor fixing structure of the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view of the motor of FIG. 5. [Figure 7] FIG. 10 is a diagram illustrating an example of an analysis model. [Figure 8] FIG. 10 is a schematic diagram illustrating an example of a rotor fixing structure of a motor according to a second embodiment. [Figure 9] FIG. 10 is a schematic diagram illustrating an example of a rotor fixing structure of a motor according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are examples for explaining the present invention, and for clarity of explanation, appropriate omissions and simplifications have been made. The present invention can be implemented in various other forms. Furthermore, unless otherwise specified, each component may be singular or plural.

[0014] Furthermore, in order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0015] In addition, when there are multiple components having the same or similar functions, they may be described by using the same reference numeral with different subscripts, or when there is no need to distinguish between these multiple components, the subscripts may be omitted.

[0016] First Embodiment Fig. 1 is a schematic perspective view illustrating an example of a rotor fixing structure of a motor according to a first embodiment. Fig. 2 is a schematic front view illustrating an example of a fixing structure of a motor according to a first embodiment, observed from one end (front end) in the axial direction.

[0017] The motor 1 according to this embodiment includes a rotor 3 and a housing 2 that houses the rotor 3. The housing 2 has a ring-shaped peripheral wall 21 that has a generally circular outer circumferential surface 20 when viewed from the front, and an end wall 22 that is provided at one end of the peripheral wall 21. In this embodiment, as will be described later, the peripheral surface 20 of the peripheral wall 21 has a plurality of teeth 24. In the illustrated example, the end wall 22 is provided at the other end (rear end).

[0018] In this application, the axial direction refers to the direction in which the central axis of the housing 2 extends, and the radial direction refers to the direction radial from the central axis on a plane perpendicular to the axial direction. Also, in this application, the inner side refers to the direction (side) approaching the central axis of the housing 2, and the outer side refers to the direction (side) away from the central axis of the housing 2.

[0019] More specifically, the motor 1 comprises a housing 2, a rotor 3 fixedly stored in the housing 2, a rotating shaft 4 that rotates integrally with the housing 2, and a stator (not shown) that is arranged between the rotor 3 and the rotating shaft 4 at a distance from both of them.

[0020] The rotor 3 is provided with magnetic poles (not shown) made of permanent magnets or the like. As an example, the rotating shaft 4 is formed integrally with the end wall portion 22 of the housing 2 so as to protrude from both the front and rear end faces thereof as shown in the figure. The rotating shaft 4 may also be formed separately and fixed to its mounting portion so as to pass through the end wall portion 22. The stator has a stator coil disposed thereon and is fixed to a member (not shown) so as not to rotate. The motor 1 is a device that rotates due to the electromagnetic interaction between the rotor 3 and the stator. The motor 1 may be made using any known technology as appropriate, as long as it does not deviate from the spirit of the present invention.

[0021] Fig. 5 is a perspective view for explaining a motor having a rotor fixing structure different from that of the present embodiment, which will be described later, and Fig. 6 is a cross-sectional view of the motor of Fig. 5.

[0022] The motor M shown in the figure is currently being developed as a high-power density motor that provides the motive power for electric transportation equipment. Motor M comprises a housing A, a rotor B fixed to housing A, a rotating shaft C, and a stator D disposed between rotor B and rotating shaft C at a distance. Housing A has multiple teeth for transmitting power on the outer surface of its ring-shaped peripheral wall, and has the function of transmitting power by meshing with other components. Motor M has a rotor fixing structure N that directly fixes rotor B to housing A, which has a power transmission function, thereby enabling further weight reduction and achieving high power density.

[0023] On the other hand, considering the above-mentioned uses of the motor M, it is expected that the rotor fixing structure N will be subjected to large external forces. Therefore, an analysis was conducted to determine whether a general rotor fixing structure, i.e., a fixing structure using press fitting or shrink fitting, could withstand the above-mentioned intended use.

[0024] Figure 7 shows an analytical model. In the figure, an input shaft S, which has teeth on its outer periphery that correspond to the teeth of the rotor fixing structure N, is installed so as to mesh with the rotor fixing structure N, and the input shaft S is rotated to perform an analysis. As a result of this analysis, it was confirmed that when the external force increases, the difference in the amount of deformation between the housing A and the rotor B increases near the point indicated by the arrow E, causing radial separation. This radial separation can lead to adverse effects such as increased wear and noise.

[0025] From these analysis results, it is believed that rotor fixing structure N cannot withstand large external forces using commonly used press fitting or shrink fitting, and there is a risk of separation in the radial direction, which could result in increased wear, increased noise, etc. Therefore, a new structure that can effectively prevent separation in the radial direction is required for rotor fixing structure N.

[0026] The rotor fixing structure 10 of the motor 1 of this embodiment has been created in response to such a demand. The rotor fixing structure 10 will be described in detail below.

[0027] 1 and 2, the rotor fixing structure 10 has a plurality of inner peripheral engaging portions 25 on the inner peripheral surface of the housing 2, and a plurality of outer peripheral engaging portions 31 on the outer peripheral surface of the rotor 3. The rotor 3 is fixed to the housing 2 by radially engaging the outer peripheral engaging portions 31 and the inner peripheral engaging portions 25.

[0028] Because the rotor fixing structure 10 is a radial engagement structure in which the rotor 3 is fixed by radial engagement with the housing 2, the two will not separate radially even if an external force is applied to the housing 2. If this rotor fixing structure 10 is applied to the rotor fixing structure N of the motor M, radial separation of the housing and the rotor can be effectively prevented even if a large external force is applied.

[0029] The housing 2 has a plurality of teeth 24 on its outer circumferential surface, similar to the housing A of the rotor fixing structure N described above. The shape and number of the plurality of teeth 24 are not particularly limited. One or more of the plurality of teeth 24 may have different shapes, but preferably teeth of the same shape are periodically arranged. The housing 2 has a plurality of teeth 24 on its outer periphery, forming a gear, and has the function of transmitting power by meshing with other components. The outer periphery of the housing 2 may be configured as a spur gear as shown in FIG. 1, or as a helical gear (double helical gear) as shown in FIG. 5. The rotor fixing structure 10 may be applied to motors other than the motor M described above.

[0030] The housing 2 may have a configuration with multiple grooves on its outer circumferential surface. The shape and number of the multiple grooves are not particularly limited. One or more of the multiple grooves may have different shapes, but preferably grooves of the same shape are periodically arranged. The housing 2 may transmit power in cooperation with other components using such grooves on its outer circumferential surface. The housing 2 may have, for example, a splined outer periphery.

[0031] The housing 2 is not particularly limited, but preferably has a number of inner peripheral engaging portions 25 corresponding to the number of teeth 24 (or grooves; the same applies hereinafter in the description of each tooth) on the outer peripheral surface of the housing 2, taking into consideration the balance of load distribution, and more preferably, the number of inner peripheral engaging portions 25 is a divisor or multiple of the number of teeth 24.

[0032] The number of outer peripheral engaging portions 31 of the rotor 3 is the same as the number of inner peripheral engaging portions 25 of the housing 2. In other words, although not particularly limited, the rotor 3 preferably has the same number of outer peripheral engaging portions 31 as the number of teeth 24 in consideration of the balance of load distribution, and more preferably, the number of outer peripheral engaging portions 31 is a divisor or multiple of the number of teeth 24.

[0033] The rotor 3 is not particularly limited, but preferably, in consideration of a balanced load distribution, the center line of at least one outer peripheral engagement portion 31 is collinear with the center line of one tooth 24 (or groove). In the example of FIG. 2, the center line of one outer peripheral engagement portion 31 and the center line of one tooth 24 are on a line F. In other words, the line F is a common center line of one outer peripheral engagement portion 31 and one tooth 24. The line F is, for example, a line extending radially from the center of the housing 2 when viewed from the front. Note that, in consideration of a balanced load distribution, the center line of at least one inner peripheral engagement portion 25 of the housing 2 may be collinear with the center line of one tooth 24 (or groove).

[0034] More preferably, the rotor 3 has a tooth 24 corresponding to each outer peripheral engaging portion 31, and the center line of the tooth 24 is on the same line. For example, in the example of Fig. 2, the outer peripheral engaging portion 31 adjacent to the outer peripheral engaging portion 31 having a common center line F has a common center line G with one tooth 24. Note that each inner peripheral engaging portion 25 may have a corresponding tooth 24, and the center line of the tooth 24 may be on the same line.

[0035] The inner circumferential engaging portion 25 and the outer circumferential engaging portion 31 may have any shape as long as they can provide a supporting force that can withstand (resist) radial separation, and there are no particular limitations on their shapes. One or more of the multiple inner circumferential engaging portions 25 may have different shapes, but preferably, those of the same shape are periodically arranged. Similarly, one or more of the multiple outer circumferential engaging portions 31 may have different shapes, but preferably, those of the same shape are periodically arranged. An example will be described in more detail below based on the illustrated example.

[0036] Fig. 3 is an enlarged view of a portion H in Fig. 2. Fig. 4 is an enlarged view of a portion K in Fig. 3.

[0037] 3, the inner circumferential engaging portion 25 protrudes radially inward from the inner circumferential surface 23 of the peripheral wall portion 21 of the housing 2. As an example, the inner circumferential engaging portion 25 has the same shape from the front end face to the rear end face of the housing 2, that is, all cross sections are formed to have the same shape as the end faces.

[0038] The outer peripheral engaging portion 31 protrudes radially outward from the outer peripheral surface 30 of the rotor 3. As an example, the outer peripheral engaging portion 31 has the same shape from the front end face to the rear end face of the rotor 3, that is, all cross sections are formed to have the same shape as the end faces. When the rotor 3 is configured as a laminate by stacking multiple plate-like bodies, as an example, the outer peripheral engaging portions 31 of the plate-like bodies are formed to have the same shape.

[0039] The rotor 3 is assembled and fixed by being inserted into the inner periphery of the housing 2 so that the outer periphery engagement portion 31 engages with the inner periphery engagement portion 25. The material of the rotor 3 is not particularly limited as long as it functions as a rotor having magnetic poles for the motor 1. The material of the housing 2 is not particularly limited as long as it is suitable for the above-mentioned uses and functions, and examples thereof include metal and resin.

[0040] As shown in FIG. 4, the inner circumferential engaging portion 25 has a first root portion 250 and a pair of first protrusions 251. The first root portion 250 is a portion that extends radially inward from the inner circumferential surface 23 of the peripheral wall portion 21 of the housing 2. The first root portion 250 in the illustrated example is generally rectangular. As an example, the inner circumferential engaging portion 25 is formed line-symmetrically with respect to the center line Q1 as shown in the figure. In other words, the pair of first protrusions 251 in the illustrated example have a shape that is line-symmetric with respect to the center line Q1.

[0041] The pair of first protrusions 251 extend in the circumferential direction (clockwise +P direction, counterclockwise -P direction) so as to be spaced apart from each other from the first root portion 250, and are located on both sides of the first root portion 250. The first protrusions 251 have a wider circumferential width at the radially inner portion. The first protrusions 251 in the illustrated example are roughly triangular in shape, with the circumferential width increasing toward the inner portion, and the portion that comes into contact with the outer peripheral surface 30 of the rotor 3 having a maximum circumferential width U.

[0042] The outer circumferential engagement portion 31 has a second root portion 310 and a pair of second protrusions 311. The second root portion 310 is a portion that extends radially outward from the outer circumferential surface 30 of the rotor 3. The second root portion 310 in the illustrated example is roughly rectangular. As an example, the outer circumferential engagement portion 31 is formed line-symmetrically with respect to the center line Q2 as illustrated. In other words, the pair of second protrusions 311 in the illustrated example have a shape that is line-symmetric with respect to the center line Q2.

[0043] The pair of second protrusions 311 extend in the circumferential direction (clockwise +P direction, counterclockwise -P direction) so as to be spaced apart from each other from the second root portion 310, and are located on both sides of the second root portion 310. The second protrusions 311 have a wider circumferential width at the radially outer portions. The second protrusions 311 in the illustrated example are roughly triangular in shape, with the circumferential width increasing toward the outer portions, and the portion that comes into contact with the inner peripheral surface 23 of the housing 2 having a maximum circumferential width V.

[0044] The inner peripheral engaging portion 25 and the outer peripheral engaging portion 31 have a first protrusion 251 with a wide portion radially inward and a second protrusion 311 with a wide portion radially outward, providing a supporting force against radial separation. More specifically, the rotor 3 is fixed to the housing 2 by the first protrusion 251 and the second protrusion 311 engaging with each other in the radial direction. In the illustrated example, the inclined surfaces of the first protrusion 251 and the second protrusion 311 have corresponding inclination angles to support each other.

[0045] The inner peripheral engaging portion 25 and the outer peripheral engaging portion 31 in the illustrated example can be said to be roughly trapezoidal, with one having a base that is wider on the radially inner side, and the other having a base that is wider on the radially outer side. The two trapezoids can also be said to be fitted together, with the heights of the trapezoids being equal and the acute angles corresponding to each other. In other words, the two can be said to fit together and prevent radial separation by fitting one into the other's engaging portions (recesses). As shown in the illustration, the inner peripheral engaging portion 25 and the outer peripheral engaging portion 31 each have roughly the same shape as the recesses between the other's engaging portions.

[0046] Second Embodiment Fig. 8 is a schematic perspective view illustrating an example of a rotor fixing structure of a motor according to a second embodiment. Fig. 9 is a schematic front view illustrating an example of a fixing structure of a motor according to a second embodiment, observed from one end (front end) in the axial direction.

[0047] The motor 1a according to this embodiment includes a rotor 3 and a housing 2a that houses the rotor 3. The configuration of the motor 1a, other than the housing 2a, such as the rotor 3, is the same as that of the motor 1 according to the first embodiment, and the same reference numerals are used here, and detailed description thereof will be omitted.

[0048] The housing 2a has a ring-shaped peripheral wall portion 21a having an outer peripheral surface 20 that is generally circular in front view, and an end wall portion 22 provided at one end (rear end) of the peripheral wall portion 21a. As shown in the figure, unlike the motor 1 of the first embodiment, the housing 2a does not have teeth 24 (or grooves) on the outer peripheral surface 20 of the peripheral wall portion 21a. Similar to the motor 1 of the first embodiment, the housing 2a has a plurality of inner peripheral engagement portions 25 on the inner peripheral surface 23 of the peripheral wall portion 21a.

[0049] That is, in the rotor fixing structure 10a of this embodiment, similar to the rotor fixing structure 10 of the first embodiment described above, the rotor 3 is fixed to the housing 2a by radially engaging multiple outer peripheral engaging portions 31 and multiple inner peripheral engaging portions 25.

[0050] The housing 2a may be subjected to external forces even if it does not have teeth 24 (or grooves) (the outer peripheral surface 20 is a smooth surface without any irregularities). In other words, the housing 2a and the external structure may be linked, interlocked, or connected by some means other than teeth or grooves. For example, the housing 2a and the external structure may be connected by welding, adhesive, or the like to transmit a load. As an example, a belt or the like may be hung on the housing 2a to transmit power.

[0051] In this embodiment, even in such a case, the rotor fixing structure 10a is a radial engagement structure in which multiple inner peripheral engagement portions 25 and multiple outer peripheral engagement portions 31 engage in the radial direction, so even if a large external force is applied, the housing 2a and the rotor 3 will not separate in the radial direction, and radial separation can be effectively prevented.

[0052] Although the present invention has been described above in terms of embodiments (examples), it should be understood that the present invention is not limited to the above-described embodiments (examples) and includes various modifications within the scope of the same technical concept. For example, the above-described examples have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one example with the configuration of another example, or to add the configuration of another example to the configuration of one example. Furthermore, it is possible to add, delete, or replace part of the configuration of each example with other configurations. [Explanation of symbols]

[0053] REFERENCE SIGNS LIST 1 motor, 10 rotor fixing structure, 2 housing, 20 outer peripheral surface, 21 peripheral wall portion, 22 end wall portion, 23 inner peripheral surface, 24 teeth, 25 inner peripheral engagement portion, 250 first root portion, 251 first protrusion, 3 rotor, 30 outer peripheral surface, 31 outer peripheral engagement portion, 310 second root portion, 311 second protrusion, 4 rotating shaft, 1a motor, 10a rotor fixing structure, 2a housing, 21a peripheral wall portion.

Claims

1. A motor comprising a rotor and a housing that houses the rotor, The housing has a plurality of inner peripheral engaging portions on its inner peripheral surface, a plurality of outer circumferential engagement portions on the outer circumferential surface of the rotor; The rotor is fixed to the housing by the outer peripheral engaging portion engaging with the inner peripheral engaging portion in the radial direction. A motor characterized by:

2. 2. The motor according to claim 1, The inner circumferential engagement portion is a first root portion extending radially inward from an inner circumferential surface of the housing; a pair of first protrusions extending circumferentially from the first root portion so as to be spaced apart from each other, The outer circumferential engagement portion is a second root portion extending radially outward from an outer circumferential surface of the rotor; a pair of second protrusions extending circumferentially from the second root portion so as to be spaced apart from each other, The first protrusion has a wide circumferential width at a radially inner portion, and the second protrusion has a wide circumferential width at a radially outer portion, and the rotor is fixed by the first protrusion and the second protrusion engaging with each other in the radial direction. A motor characterized by:

3. 2. The motor according to claim 1, The housing has a plurality of teeth or a plurality of grooves on its outer peripheral surface, The number of the inner circumferential engaging portions is a divisor or multiple of the number of the teeth or the number of the grooves. A motor characterized by:

4. 4. The motor according to claim 3, The center line of at least one of the outer peripheral engaging portions is on the same straight line as the center line of one of the teeth or grooves. A motor characterized by:

5. A rotor fixing structure for a motor including a rotor and a housing that houses the rotor, The housing has a plurality of inner peripheral engaging portions on its inner peripheral surface, a plurality of outer circumferential engagement portions on the outer circumferential surface of the rotor; The rotor is fixed to the housing by radially engaging the outer peripheral engaging portion and the inner peripheral engaging portion. A rotor fixing structure characterized by the above.

6. The rotor fixing structure according to claim 5, The inner circumferential engagement portion is a first root portion extending radially inward from an inner circumferential surface of the housing; a pair of first protrusions extending circumferentially from the first root portion so as to be spaced apart from each other, The outer circumferential engagement portion is a second root portion extending radially outward from an outer circumferential surface of the rotor; a pair of second protrusions extending circumferentially from the second root portion so as to be spaced apart from each other, The first protrusion has a wide circumferential width at a radially inner portion, and the second protrusion has a wide circumferential width at a radially outer portion, and the rotor is fixed by the first protrusion and the second protrusion engaging with each other in the radial direction. A rotor fixing structure characterized by the above.

7. The rotor fixing structure according to claim 5, The housing has a plurality of teeth or a plurality of grooves on its outer peripheral surface, The number of the inner circumferential engaging portions is a divisor or multiple of the number of the teeth or the number of the grooves. A rotor fixing structure characterized by the above.

8. The rotor fixing structure according to claim 7, The center line of at least one of the outer peripheral engaging portions is on the same straight line as the center line of one of the teeth or grooves. A rotor fixing structure characterized by the above.

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