JP2010233328A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor capable of reliably maintaining a force of fixing a stator core in a wide usage temperature zone, and reducing the manufacturing cost. <P>SOLUTION: In the brushless motor 1 in which the stator core 12 having a coil wound therearound is internally fitted and fixed on the inner circumferential surface of a stator housing 11, a cylindrical member 71 having spring properties in a diameter direction is interposed between the stator housing 11 and the stator core 12, and the cylindrical member 71 has a plurality of inside protrusions 75 formed on the inner circumferential surface and a plurality of outside protrusions 74 formed on the outer circumferential surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a brushless motor.

Generally, a brushless motor is composed of a stator around which a coil is wound, and a rotor that is rotatably provided to the stator and has a magnet, and rotates the rotor by controlling energization of the coil. It has become. Brushless motors are roughly classified into a so-called outer rotor type motor in which the rotor rotates on the outer peripheral surface side of the stator and a so-called inner rotor type motor in which the rotor rotates on the inner peripheral surface side of the stator.
The stator of the inner rotor type motor includes a cylindrical stator housing and a stator core that is fitted and fixed to the inner peripheral surface of the stator housing. The stator core is formed in a substantially cylindrical shape by laminating electromagnetic steel plates, for example, and a coil is wound around the stator core.

  Here, when the stator core is fitted and fixed to the inner peripheral surface of the stator housing, shrink fitting is often employed. That is, the inner diameter of the stator housing is formed to be slightly smaller than the outer diameter of the stator core, and the stator housing is heated in advance when the stator core is assembled. Then, the stator core is inserted into the stator housing in an expanded state so that the inner diameter of the stator housing is larger than the outer diameter of the stator core. Thereafter, when the stator housing is cooled, the contracted stator housing presses the stator core from the outer peripheral side, so that the stator core can be fixed (see, for example, Patent Document 1).

JP-A-9-84282

  However, in the above-described prior art, when the stator housing is formed by aluminum die casting in response to a demand for weight reduction or the like, the stator core formed by laminating the linear expansion coefficient of the stator housing and electromagnetic steel plates The value differs greatly depending on the linear expansion coefficient. For this reason, there is a problem that it becomes difficult to maintain the fixing force of the stator housing to the stator core when the operating temperature condition is increased.

  Further, in order to maintain the fixing force of the stator housing to the stator core in a wide temperature range, it is conceivable that the stator core is shrink-fitted and fixed and an adhesive is applied between the stator housing and the stator core. However, there is a problem that the manufacturing cost increases as the adhesive is used.

  Accordingly, the present invention has been made in view of the above-described circumstances, and a brushless motor that can reliably maintain the fixing force of the stator core in a wide range of operating temperatures and can reduce manufacturing costs. It is to provide.

In order to solve the above-mentioned problem, the invention described in claim 1 is a brushless motor in which a stator core around which a coil is wound is fitted and fixed to an inner peripheral surface of a stator housing. A cylindrical member having a spring property is interposed therebetween, and the cylindrical member has a plurality of first protrusions formed on the inner peripheral surface and a plurality of second protrusions on the outer peripheral surface. A protruding line portion is formed.
With this configuration, if the cylindrical member is interposed between the stator housing and the stator core in a state where the first ridges and the second ridges are elastically deformed, the stator housing expands at a high temperature. Even in this case, the decrease in the fixing force of the stator core can be compensated by the frictional resistance generated by the restoring force of the first and second ridges. For this reason, the fixing force of the stator core can be reliably maintained in a wide range of operating temperatures.
Further, by using the cylindrical member, it is not necessary to apply an adhesive between the stator housing and the stator core, so that the manufacturing cost can be reduced.

According to a second aspect of the present invention, the plurality of first ridges are formed along the axial direction, and the outer peripheral surface of the stator core is provided with a portion corresponding to the first ridges, One groove is formed along the axial direction.
By comprising in this way, the 1st protruding item | line part and the 1st groove | channel will be in the mutually engaged state, and it can prevent reliably the rotational movement of the stator core with respect to a stator housing. For this reason, it is possible to reliably prevent the aging of the relative positional relationship between the stator housing and the stator core.
Here, for example, in the case of providing a rotational position detection device for detecting the rotational position of the rotor in the brushless motor, the angle of the rotational position detection device is adjusted based on the relative position between the stator core and the rotor. In many cases, the rotational position detection device is fixed to the stator housing via a bracket or the like. In this case, if the relative position between the stator housing and the stator core shifts with time, the rotational position detection accuracy of the rotor deteriorates accordingly. For this reason, it becomes possible to prevent aged deterioration of the rotational position detection accuracy of the rotor, for example, by reliably preventing the rotational movement of the stator core with respect to the stator housing.

According to a third aspect of the present invention, the plurality of second ridges are formed along the axial direction, and an inner peripheral surface of the stator housing has a portion corresponding to the second ridges. The second groove is formed along the axial direction.
By comprising in this way, the 2nd protruding item | line part and the 2nd groove | channel will be in the state mutually engaged, and the rotational movement of the stator core with respect to a stator housing can be prevented more reliably. For this reason, it becomes possible to provide a highly reliable brushless motor having a fail-safe function.

According to the present invention, when the cylindrical member is interposed between the stator housing and the stator core in a state where the first ridges and the second ridges are elastically deformed, the stator housing expands at a high temperature. Even so, a decrease in the fixing force of the stator core can be compensated by the frictional resistance generated by the restoring force of the first and second ridges. For this reason, the fixing force of the stator core can be reliably maintained in a wide range of operating temperatures.
Further, by using the cylindrical member, it is not necessary to apply an adhesive between the stator housing and the stator core, so that the manufacturing cost can be reduced.

The longitudinal cross-sectional view of the brushless motor in embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is a perspective view of the stator core in the embodiment of the present invention. It is a perspective view of the cylindrical member in embodiment of this invention. It is the B section enlarged view of FIG. It is a top view of the stator core in the embodiment of the present invention. It is explanatory drawing which shows the attachment state of the stator core in the embodiment of this invention, a stator housing, and a cylindrical member. It is action | operation explanatory drawing of the cylindrical member in embodiment of this invention.

(Brushless motor)
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view of the brushless motor 1.
As shown in the figure, the brushless motor 1 is used in, for example, an electric power steering device (EPS), and has a stator 2 and a rotor 3 disposed in the stator 2. The rotor 3 is rotatably supported by a bracket 4 fixed to the stator 2.

  The rotor 3 has a rotary shaft 22 formed of a hollow shaft, and a rack shaft (not shown) can be inserted into the rotary shaft 22. The rack shaft forms a rack and pinion mechanism in the gear box of the vehicle, and is movable in the axial direction of the brushless motor 1 in accordance with an operation of a steering wheel (not shown). Both ends of the rack shaft are connected to the wheels of the vehicle via a knuckle arm or the like.

One end of the rotary shaft 22 is pivotally supported by a bearing 25 press-fitted into the bracket 4. A resolver rotor 26a constituting one of the resolvers 26 for detecting the rotational position of the rotor 3 is fixed to the outer peripheral surface on one end side. The resolver rotor 26a is configured by a substantially annular permanent magnet having a plurality of salient poles (not shown) arranged at equal intervals in the circumferential direction, or a substantially annular laminated steel plate.
At the center of the rotating shaft 22 in the axial direction, a laminated body 32 of metal plates is fitted and fixed to the outer peripheral surface, and a tile-like rotor magnet 33 is fixed to the outer peripheral surface via a magnet holder 34. The rotor magnet 33 has a plurality of magnetic poles arranged in the circumferential direction.

2 is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 3 is a perspective view of the stator core 12.
As shown in FIGS. 1 to 3, the stator 2 includes a substantially cylindrical stator housing 11, and a substantially cylindrical stator core 12 fitted and fixed to the stator housing 11 via a cylindrical member 71 having a spring property. It consists of
The stator housing 11 has bolt holes 13 formed at the respective peripheral edge portions of the released both ends, and the bracket 4 and other brackets (not shown) can be fixed. An end portion on the side of the bracket 4 is formed with an inlay portion 11 a that is used when the stamper is joined to the bracket 4.

  The stator core 12 uses a split core system that can be split in the circumferential direction. The divided core 14 divided from the stator core 12 is formed by laminating plates of magnetic material in the axial direction or pressurizing magnetic metal powder, and includes a core body 15 extending in the circumferential direction. Have. The core body 15 is a portion that forms an annular magnetic path of the stator core 12 and is a portion that is fixed to the inner peripheral surface of the stator housing 11, and is formed in a substantially arc shape in an axial plan view.

  Both end portions in the circumferential direction of the core body 15 are connection portions 15 a and 15 b which are connected to the other core body 15 by press-fitting. One connecting portion 15a has a convex shape, and the other connecting portion 15b has a concave shape capable of receiving one connecting portion 15a. As a result, the core bodies 15 can be connected to form a substantially cylindrical stator core 12.

  On the inner peripheral side of each core body 15, a teeth portion 16 is integrally extended from the substantially central portion in the circumferential direction toward the center of rotation so as to extend along the radial direction. The teeth part 16 is a salient pole, and the coil 7 is wound on the insulator 6 after the insulator 6 is attached thereto. The end portion 45 that is the winding start end and the winding end end of the coil 7 is drawn toward the side opposite to the bracket 4 (the right side in FIG. 1).

Further, an inner peripheral portion 17 extending in the circumferential direction is formed at an end portion on the inner peripheral side of the tooth portion 16. Two concave portions 18 are formed on the inner peripheral surface of the inner peripheral portion 17, and three teeth are formed on one core body 15 by the two concave portions 18. .
On the other hand, a groove 19 is formed on the outer peripheral side of each core main body 15 over the entire longitudinal direction (axial direction, vertical direction in FIG. 3) of the core main body 15 at substantially the center in the circumferential direction. The groove 19 has a substantially U-shaped cross section and is formed along the longitudinal direction. The groove 19 is inserted with an inner convex portion 75 described later formed in the cylindrical member 71.

(Cylindrical member)
4 is a perspective view of the cylindrical member 71, FIG. 5 is an enlarged view of a portion B of FIG. 4, and FIG. 6 is a plan view of the stator core 12.
As shown in FIGS. 3 to 6, the cylindrical member 71 is formed of a metal plate material having a spring property (for example, SUS, SPCC), and has a cylindrical portion main body 72. The inner diameter of the cylindrical portion main body 72 is set so as to substantially match the outer diameter of the stator core 12, and can be fitted onto the stator core 12. The length L1 in the longitudinal direction (axial direction) of the cylindrical portion main body 72 is set to be approximately half of the length L2 in the longitudinal direction (axial direction) of the stator core 12.

  An inner flange portion 73 is formed on one peripheral edge of the cylindrical portion main body 72. The inner flange portion 73 is bent and extended from the peripheral edge of the cylindrical portion main body 72 to a portion where the insulator 6 of the stator core 12 is mounted. The cylindrical member 71 is positioned in the axial direction by the inner flange portion 73 abutting against one end surface 12a (see FIG. 1) of the stator core 12 on the bracket 4 side. That is, the cylindrical member 71 is mounted so as to cover the space from the one end surface 12a of the stator core 12 to the substantially axial center.

  Further, on the outer peripheral surface of the cylindrical portion main body 72, a plurality of outer ridges 74 extending along the longitudinal direction from the vicinity of the inner flange portion 73 to the other peripheral edge are formed at equal intervals in the circumferential direction. ing. On the other hand, on the inner peripheral surface of the cylindrical portion main body 72, inner ridges 75 are formed at locations corresponding to both sides of the outer ridges 74. The inner ridge 75 also extends along the longitudinal direction from the vicinity of the inner flange 73 to the other peripheral edge.

  The outer ridge 74 is gradually tapered from the outer peripheral surface of the cylindrical portion main body 72 toward the radially outer side, and has an arcuate surface 74a at the tip. On the other hand, the pair of inner ridges 75, 75 formed on both sides of each outer ridge 74 are formed so as to protrude radially inward from the root of the outer ridge 74. The inner ridge 75 is gradually tapered from the inner peripheral surface of the cylindrical portion main body 72 toward the radially inner side, and has an arcuate surface 75a at the tip. That is, the outer peripheral surface of the cylindrical portion main body 72 is in a state in which the surface 76a of the outer ridge 74 and the back surface 77b of the inner ridge 75 are exposed and have irregularities.

Further, the outer ridge 74 is formed larger than the inner ridge 75. More specifically, the height H1 from the cylindrical body 72 to the top of the arcuate surface 74a of the outer ridge 74 is a height H2 from the cylindrical body 72 to the top of the arcuate surface 75a of the inner ridge 75. Is set higher than.
Further, the inner ridges 75, 75 are grooves in which the two inner ridges 75, 75 located on both sides of the outer ridge 74 are paired and the apex of these arcuate surfaces 75 a is formed in the stator core 12. 19 is inserted in each.

This will be described in more detail with reference to FIG. FIG. 7 is an explanatory view showing an attachment state of the stator core 12, the stator housing 11, and the cylindrical member 71.
As shown in the figure, the pair of inner ridge portions 75, 75 are set such that the interval W1 between the apexes of the arcuate surface 75a is slightly smaller than the groove width W2 of the groove 19 of the stator core 12. The height H2 from the cylindrical portion main body 72 to the apex of the arcuate surface 75a of the inner ridge 75 is set slightly smaller than the groove depth H3 of the groove 19. For this reason, a pair of inner side protruding item | line parts 75 and 75 will be in the state inserted in the one groove | channel 19, respectively. At this time, the surface 77 a of the inner ridge 75 is in contact with the corner of the groove 19.

  Here, a groove 10 is formed on the inner peripheral surface of the stator housing 11 at a portion corresponding to the outer protruding portion 74. The groove 10 has a substantially U-shaped cross section and is formed along the longitudinal direction. That is, the outer ridge 74 is inserted in the groove 10 of the stator housing 11. The groove depth H <b> 4 of the groove 10 is set so that the bottom surface 10 a of the groove 10 can come into contact with the arcuate surface 74 a of the outer ridge 74. Further, the groove width W <b> 3 of the groove 10 is set so that the corner portion of the groove 10 can contact the surface 76 a of the outer ridge 74.

  With such a configuration, the rotational movement of the cylindrical member 71 relative to the stator core 12 is restricted by inserting the inner convex strip 75 of the cylindrical member 71 into the groove 19 of the stator core 12. Further, by inserting the outer ridge 74 of the cylindrical member 71 into the groove 10 of the stator housing 11, the rotational movement of the cylindrical member 71 relative to the stator housing 11 is restricted. As a result, the rotational movement of the stator core 12 with respect to the stator housing 11 is restricted.

  As shown in FIG. 1, the terminal portion 45 of each coil 7 wound around the stator core 12 is connected to the bus bar unit 46. The bus bar unit 46 is disposed on the opposite side of the stator housing 11 from the bracket 4 so as to surround the periphery of the rotary shaft 22. The bus bar unit 46 is connected to a power connector 47 projecting from the outer peripheral portion of the stator housing 11.

  A receiving portion 48 is integrally formed at one end of the power connector 47. The receiving portion 48 is formed such that one end portion of a power cable (not shown) extending from an external power source (not shown) can be fitted and fixed, and current can be supplied from the external power source to the bus bar unit 46. Further, on the other end side of the power connector 47, a flange portion 49 that extends in close contact with the outer surface of the stator housing 11 is extended. Furthermore, the power connector 47 is integrally formed with a connector terminal 64 penetrating from one end to the other end. The other end of each connector terminal 64 (the end on the bus bar unit 46 side) is electrically connected to the bus bar unit 46.

(bracket)
The bracket 4 is formed in a substantially cylindrical shape, and is fastened and fixed to the stator housing 11 with bolts 24. At the end of the bracket 4, a joint 4 a that fits into the spigot 11 a when being abutted against the stator housing 11 is integrally formed. A packing 23 such as an O-ring is mounted in a groove carved in the outer periphery of the joint 4a. The other end of the bracket 4 opens so that the rack shaft can be inserted. A bearing 25 is press-fitted into the bracket 4 on the opening side. A resolver stator 26b constituting the other of the resolver 26 is fixed to the stator 2 side of the bearing 25. A sensor connector 27 for taking out an electric signal from the resolver stator 26b is fixed to the outer periphery of the bracket 4.

The resolver stator 26b has a core 41 configured by laminating plates made of a magnetic material, and a tooth (not shown) around which a resolver coil 54 is wound is extended toward the radially inner side of the core 41. Yes.
As described above, the resolver 26 constituted by the resolver rotor 26a and the resolver stator 26b uses the fact that the gap permeance between the two rotors 26a and 26b changes into a sine wave with the rotation angle of the resolver rotor 26a. The rotational position is detected. For this reason, the detection result of the resolver 26 is greatly influenced by the mounting accuracy of the resolver rotor 26a and the resolver stator 26b.

The end of the winding of each resolver coil 54 is electrically connected to a sensor connector 27 that protrudes from the outer periphery of the bracket 4.
The sensor connector 27 has a receiving portion 61 into which a signal cable can be fitted at one end, and the other end is inserted into the bracket 4. In addition, a flange portion 62 that extends in close contact with the outer surface of the bracket 4 is provided on the outer periphery on the other end side. Further, a connector terminal 63 penetrating from one end to the other end is integrally formed in the sensor connector 27, and a resolver coil 54 is electrically connected to this other end (the end on the resolver stator 26b side). ing.

(Function)
Next, a method for assembling the stator 2 will be described with reference to FIGS. FIG. 8 is an explanatory diagram of the operation of the cylindrical member 71.
Here, the inner diameter of the stator housing 11 is set to be slightly smaller than the outer diameter of the stator core 12.
In such a state, first, the cylindrical member 71 is mounted on the stator core 12. At this time, the cylindrical member 71 is inserted into the stator core 12 with the inner flange portion 73 of the cylindrical member 71 facing forward. Further, the inner ridge portion 75 of the cylindrical member 71 is inserted in a state where it is aligned with the groove 19 of the stator core 12. The cylindrical member 71 is inserted until the inner flange portion 73 comes into contact with the one end surface 12 a of the stator core 12.

  Subsequently, the stator housing 11 is heated and expanded so that the inner diameter of the stator housing 11 is larger than the outer diameter of the stator core 12. Then, the stator core 12 on which the cylindrical member 71 is mounted is inserted into the stator housing 11. At this time, the stator core 12 is inserted in a state where the inner flange portion 73 of the cylindrical member 71 faces the stator housing 11 side. Further, the outer ridge 74 of the cylindrical member 71 is inserted in a state of being aligned with the groove 10 of the stator housing 11.

  Thereafter, the stator housing 11 is cooled. As a result, the stator housing 11 contracts and presses the outer ridge 74 of the cylindrical member 71 radially inward (see arrow X in FIG. 8). The inner ridge 75 of the cylindrical member 71 is elastically deformed toward the outer side in the circumferential direction when the outer ridge 74 is pressed and elastically deformed (see arrow Y in FIG. 8).

  For this reason, a restoring force is generated in each of the outer ridge 74 and the inner ridge 75. This restoring force increases the frictional resistance between the stator housing 11 and the cylindrical member 71 and increases the frictional resistance between the cylindrical member 71 and the stator core 12. Increase frictional resistance. Thereby, the stator core 12 is securely fixed in the stator housing 11, and the assembly of the stator 2 is completed.

(effect)
Therefore, according to the above-described embodiment, since the outer protruding portion 74 of the cylindrical member 71 is inserted into the groove 10 of the stator housing 11, both the members 10 and 74 are restricted from moving in the circumferential direction. It will be in the engaged state. In addition, since the inner ridge 75 of the cylindrical member 71 is inserted into the groove 19 of the stator core 12, both 19 and 75 are engaged so as to restrict movement in the circumferential direction. For this reason, the stator core 12 with respect to the stator housing 11 can reliably prevent rotational movement.
Further, since the protruding strips 74 and 75 are inserted into the grooves 10 and 19, respectively, this functions as a fail-safe, and the stator core 12 can be prevented from shifting over time. For this reason, it is possible to prevent the detection accuracy of the resolver 26 from aging and to provide the brushless motor 1 with high reliability.

Furthermore, since the frictional resistance between the stator housing 11 and the cylindrical member 71 and the frictional resistance between the cylindrical member 71 and the stator core 12 are increased by the restoring force of each of the ridges 74 and 75, the stator core 12 is pivoted. It is possible to reliably prevent movement in the direction.
Even if the usage environment of the brushless motor 1 is high and the stator housing 11 expands, the protrusions 74 and 75 of the cylindrical member 71 are assembled in an elastically deformed state. In this case, it is possible to maintain the fixing force to the stator core 12. For this reason, the adhering force of the stator housing 11 to the stator core 12 can be maintained in a wide range of operating temperatures.

  In addition, since the stator core 12 is fixed using the cylindrical member 71, there is no need to apply an adhesive between the stator housing 11 and the stator core 12 for the purpose of fail-safe, for example. For this reason, manufacturing cost can be reduced.

The present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention.
For example, in the above-described embodiment, the case where the brushless motor 1 is applied to an electric power steering device mounted in a vehicle such as an automobile has been described. However, the present invention is not limited to this, and the brushless motor 1 can be widely applied to other electrical components.

  Further, in the above-described embodiment, the groove 10 is formed on the inner peripheral surface of the stator housing 11, and the groove 19 is formed on the outer peripheral surface of the stator core 12. The case where the parts 74 and 75 were inserted was demonstrated. However, the present invention is not limited to this, and the groove 10 may not be formed on the inner peripheral surface of the stator housing 11, and the groove 19 may not be formed on the outer peripheral surface of the stator core 12. Even in this configuration, the fixing force of the stator core 12 can be sufficiently maintained in a wide range of operating temperatures by the frictional force generated by the restoring force of the convex portions 74 and 75 of the cylindrical member 71 in addition to the shrink-fitting and fixing of the stator core 12. Is possible.

  Furthermore, in the above-described embodiment, a case has been described in the cylindrical member 71 where the longitudinal length L1 of the cylindrical portion main body 72 is set to be approximately half of the longitudinal length L2 of the stator core 12 (FIG. 3). reference). However, the present invention is not limited to this, and the length L1 of the cylindrical body 72 may be set according to the usage environment of the brushless motor 1. That is, the frictional resistance between the stator housing 11 and the cylindrical member 71 and the frictional resistance between the cylindrical member 71 and the stator core 12 increase as the length L1 of the cylindrical body 72 increases. For this reason, what is necessary is just to set length L1 of the cylindrical part main body 72 according to the adhering force required with respect to the stator core 12. FIG.

1 Brushless motor 2 Stator 3 Rotor 4 Bracket 10 Groove (second groove)
11 Stator housing 12 Stator core 19 Groove (first groove)
71 Cylindrical member (Cylinder member)
74 Outer ridge (second ridge)
75 Inner ridge (first ridge)

Claims (3)

In a brushless motor in which a stator core around which a coil is wound is fitted and fixed to the inner peripheral surface of the stator housing,
Between the stator housing and the stator core, a cylindrical member having a spring property in the radial direction is interposed,
The cylindrical member has a plurality of first ridges formed on the inner peripheral surface and a plurality of second ridges formed on the outer peripheral surface. The plurality of first ridges are formed along the axial direction,
2. The brushless motor according to claim 1, wherein a first groove is formed along an axial direction in a portion corresponding to the first ridge portion on the outer peripheral surface of the stator core. The plurality of second ridges are formed along the axial direction,
3. The second groove according to claim 1, wherein a second groove is formed along an axial direction in a portion corresponding to the second protrusion on the inner peripheral surface of the stator housing. Brushless motor.

Images