JP2008141942A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a stator core from rotating with respect to a stator housing, and also to prevent liquid from dripping from a coating material. <P>SOLUTION: A plate 21 is mounted on the stator housing 11 of a brushless motor 1. The plate 21 is regulated from rotating with respect to the stator housing 11 by inserting a first claw part 62 into a locking groove 43 of the stator housing 11. The plate 21 is regulated from rotating with respect to the stator core 12 by inserting a second claw part into the outer peripheral groove of the stator core 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a brushless motor used for an electric power steering device or the like.

As a motor used for an electric power steering apparatus, it is known to use a small and high-performance brushless motor. For example, as disclosed in Patent Document 1, a brushless motor used in an electric power steering apparatus includes a stator core that is press-fitted and fixed to the inner periphery of a stator housing that is open at both ends. Are rotatably arranged. The stator core is wound with a coil after the insulator is mounted, and controls the rotation of the rotor by energizing the coil according to the rotational position of the rotor. When the rotor is rotated, the rack shaft reciprocates via the ball screw mechanism, and the steering force of the steering wheel is assisted. The rotational position of the rotor is detected using a resolver. The resolver stator is fixed to the inner periphery of the housing, and the resolver rotor is fixed to the rotor.
JP 2005-51980 A

However, in order to press-fit and fix the stator core so as not to rotate with respect to the stator housing, high dimensional accuracy is required, which increases the manufacturing cost. When the stator housing and the stator core are provided with a non-rotating structure, if the stator core is skewed, the stator housing must be machined along the skew direction, which is complicated and expensive.
Some conventional stators have a coil covered with a coating material to prevent the coil from being worn by vibration. The coating material is cured after being dropped onto the coil.
However, before the coating material dries, excessive coating material may hang down on the spigot part of the stator housing or the work place. When it hangs down on the spigot portion of the stator housing, it cannot be fitted to the mating member to be spliced and must be repaired. When it hangs down on the work place, it causes the working environment to deteriorate.
The present invention has been made in view of such circumstances, and a main object thereof is to prevent the rotation of the stator core relative to the stator housing and to prevent the coating material from dripping.

The invention according to claim 1 of the present invention for solving the above-mentioned problems is a brushless motor in which a stator core around which a coil is wound is disposed on the inner periphery of a stator housing, and a rotor is rotatably disposed inside the stator core. The stator core around which the coil is wound is fixed to the inner periphery of the stator housing, and a plate provided with a detent portion for preventing the stator housing and the stator core from rotating is provided adjacent to the stator core. The featured brushless motor.
In this brushless motor, since the plate provided with the anti-rotation portion is provided, the anti-rotation between the stator core and the stator housing can be reliably performed via the plate. Further, since it is not necessary to perform complicated machining on the stator housing and the stator core, the manufacturing becomes easy and the machining cost can be reduced.

According to a second aspect of the present invention, in the brushless motor according to the first aspect, the rotation preventing portion includes a first claw portion that is non-rotatably fitted to the stator housing, and a first nail portion that is non-rotatably fitted to the stator core. It has the plate comprised by the 2 nail | claw part, It is characterized by the above-mentioned.
In this brushless motor, the plate is non-rotatably attached to each of the stator core and the stator housing. The stator core and the stator housing are restricted from relative movement in the rotational direction via the plate.

According to a third aspect of the present invention, in the brushless motor according to the first aspect, the rotation preventing portion is a flange portion on the outer peripheral side of the plate that is press-fitted into the inner periphery of the stator housing.
Since this brushless motor prevents rotation between the stator core and the stator housing via a plate and does not adjust the alignment, it can be manufactured more easily and the processing cost can be reduced.

The invention according to claim 4 is the brushless motor according to any one of claims 1 to 3, wherein the plate has a recess capable of forming a liquid pool of the coating material of the coil. To do.
In this brushless motor, excess coating material accumulates in the recesses of the plate. The coating material does not sag on the spigot part of the stator housing or the floor surface of the work place.

According to a fifth aspect of the present invention, in the brushless motor according to any one of the first to fourth aspects, the plate is made of a magnetic material, and the resolver for detecting the rotational position of the rotor and the It is arranged between the coils.
In this brushless motor, the magnetic flux from the coil toward the resolver is blocked by the plate.

  According to the present invention, rotation between the stator core and the stator housing is prevented by the plate. By using the plate, the processing of the stator core and the stator housing can be minimized, so that the manufacture is facilitated and the cost can be reduced.

The best mode for carrying out the invention will be described in detail with reference to the drawings. 1 to 5 show a first embodiment of the present invention.
FIG. 1 shows a brushless motor used in an electric power steering apparatus. The brushless motor 1 includes a stator 2 and a rotor 3 disposed in the stator 2, and the rotor 3 is rotatably supported by a bracket 4 fixed to the stator 2. A rotor shaft (not shown) can be inserted into the rotor 3. The rack shaft forms a rack and pinion mechanism in the gear box, and is movable in the axial direction of the brushless motor 1 in accordance with the operation of the steering wheel. Both ends of the rack shaft are connected to the wheels of the vehicle via a knuckle arm or the like.

  In the stator 2, a stator core 12 is press-fitted and fixed to the inner periphery of a cylindrical stator housing 11. The stator housing 11 is formed with screw holes 13 at the respective peripheral edge portions of the released both ends, so that the bracket 4 and other brackets (not shown) can be fixed. The end portion on the bracket 4 side is formed with an inlay portion 11 </ b> A that is used when inlay joining with the bracket 4.

The stator core 12 has a plurality of teeth 14 extending from an annular outer peripheral portion toward the center. A coil 16 is wound around each tooth 14 after the insulator 15 is mounted. The stator core 12 of this embodiment is skewed with respect to the axis.
When the stator 2 is manufactured, a core unit having a shape in which the stator core 12 is divided into a plurality of parts in the circumferential direction is manufactured, and after winding the coil 16, the plurality of core units are joined to form the stator core 12.
The winding of each coil 16 is connected to a terminal 17 disposed on the opposite side of the open end to which the bracket 4 is fixed. The terminal 17 is electrically connected to a connection terminal 18 protruding from the side of the stator housing 11 so that a current can be supplied from an external power source.
The coil 16 is protected by being covered with a coating material. The coating material forms a liquid pool 22 on a plate 21 provided on the bracket 4 side.

  The bracket 4 has a cylindrical shape and is fixed to the stator housing 11 with screws 72. At the end of the bracket 4, there is a joint 4 </ b> A that fits into the spigot 11 </ b> A when abutting against the stator housing 11, and a packing 23 such as an O-ring is mounted in a groove carved on the outer periphery of the joint 4 </ b> A. Has been. 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 26 </ b> A of a resolver 26 that detects the rotational position of the rotor 3 is fixed to the stator 2 side of the bearing 25. The resolver stator 26A has a configuration in which a plurality of coils are wound around a core, and outputs a predetermined electric signal by the rotation of the resolver rotor 26B fixed to the rotor 3 side. A terminal 27 for taking out an electrical signal from the resolver stator 26A is fixed to the side portion of the bracket 4.

The rotor 3 has a rotating shaft 31 formed of a hollow shaft. One end of the rotating shaft 31 is pivotally supported by a bearing 25 press-fitted into the bracket 4. A resolver rotor 26 </ b> B constituting the resolver 26 is fixed to the outer periphery on one end side. The resolver rotor 26B has a configuration in which permanent magnets are arranged so that magnetic poles are alternately arranged in the circumferential direction. Further, a rotor magnet 33 made of an annular permanent magnet is fixed by a bracket 34 through a metal plate laminated body 32 at a position facing the stator core 12 on the outer periphery of the rotating shaft 31. The rotor magnet 33 has a plurality of magnetic poles arranged in the circumferential direction.
A ball nut (not shown) is fixed to the end of the rotating shaft 31. This ball nut constitutes a ball nut mechanism by interposing a plurality of balls with a ball screw formed on a part of the rack shaft. The ball nut is rotatably supported by a bearing provided on a bracket (not shown) fixed to the stator housing 11.

Here, as shown in FIG. 2, a support portion 41 used to support the plate 21 is formed on the inner periphery of the stator housing 11 on the side of the spigot portion 11 </ b> A. The support portion 41 includes an annular groove 42 and a locking groove 43 that is shallower than the annular groove 42. The locking groove 43 is a key groove formed in only one place. The stator housing 11 is manufactured by casting and is dimensioned by cutting an inner diameter portion. The support portion 41 is formed when the inner diameter portion is cut.
As shown in FIG. 3, a skewed groove 45 is formed on the outer peripheral surface of the stator core 12. By providing the groove 45, the contact area with the stator housing 11 is reduced to reduce the press-fitting load, and the stator housing 11 is prevented from being deformed during press-fitting.
The grooves 45 are formed at equal intervals in the circumferential direction.

As shown in FIG. 1 to FIG. 4, the plate 21 has a ring-shaped disc that rises up to form an annular rib 51 and an outer peripheral edge that rises in the same direction as the rib 51 to form a side wall. 52 is formed. The recess 53 formed between the rib 51 and the side wall 52 has a size capable of inserting the insulator 15 and the coil 16. In this embodiment, the plate 21 is manufactured by pressing a magnetic material such as iron.
The inner diameter of the plate 21 is a size that does not interfere with the rotating shaft 31. The outer diameter of the side wall 52 is equal to or smaller than the inner diameter of the joint portion 4 </ b> A of the bracket 4. A locking portion 61 used to fix the plate 21 to the stator 2 is integrally extended from the side wall 52.

The locking portion 61 extends the end portion of the side wall 52 radially outwardly in a flange shape, and raises the first claw portion (rotation preventing portion) 62 and the second claw portion (rotation prevention portion) 63 in the axial direction. The configuration is One first claw portion 62 is formed in the circumferential direction. A plurality of second claw parts 63 are provided at equal intervals in the circumferential direction, for example, every 90 °, avoiding the formation position of the first claw part 62.
The outer diameter of the locking portion 61 is substantially equal to the inner diameter expanded by the annular groove 42 of the stator housing 11. The first claw portion 62 is a key that uses the locking groove 43 of the stator housing 11 as a key groove, and is used as a detent for the stator housing 11. The thickness of the first claw portion 62 in the radial direction is equal to or less than the depth of the locking groove 43. The circumferential width of the first claw portion 62 is substantially equal to the circumferential width of the locking groove 43. The second claw portion 63 is a key that is disposed radially inward from the first claw portion 62 and uses the groove 45 of the stator core 12 as a key groove. The thickness of the second claw portion 63 in the radial direction is equal to or less than the depth of the groove 45. The circumferential width of the second claw portion 63 is substantially equal to the circumferential width of the groove 45.

  When manufacturing the brushless motor 1, the stator core 12 is formed by combining the core unit around which the coil 16 is wound from above the insulator 15. The plate 21 is mounted so that the second claw portion 63 is inserted into the groove 45 on the outer periphery of the stator core 12. The insulator 15 and a part of the coil 16 are accommodated in the recess 53 of the plate 21. The second claw portion 63 is fitted in the groove 45, and the rotation of the plate 21 relative to the stator core 12 is prevented. In this state, the stator core 12 is press-fitted into the stator housing 11. At this time, the position in the rotational direction is adjusted so that the first claw portion 62 of the plate 21 is inserted into the locking groove 43 on the stator housing 11 side. The locking portion 61 is received in the annular groove 42, and the outer peripheral edge of the locking portion 61 and the stator housing 11 are fitted to fix the plate 21 to the stator housing 11. Further, the first claw portion 62 is fitted into the locking groove 43, and the rotation of the plate 21 relative to the stator housing 11 is prevented.

As shown in FIG. 5, when coating the coil 16, the coating material is injected from the position indicated by the dashed arrow to the end of the coil 16 disposed on the upper side with the plate 21 side down. The coating material covers the coil 16 while flowing downward along the winding of the coil 16. Excess coating material is dropped from the lower end of the coil 16 into the recess 53 of the plate 21.
Since a sufficient space is secured in the plate 21, a surplus coating material forms a liquid pool in the recess 53 and does not flow out to the outside. When the coating material is dripped sufficiently, the coating material is dried.

  When the brushless motor 1 manufactured in this way is driven, a control device (not shown) energizes the predetermined coil 16 in accordance with the operation of the steering wheel. The rotor 3 is rotated by a magnetic field formed by the coil 16. The rotation of the rotor 3 is converted into a forward / backward movement of the rack shaft by the ball screw mechanism, and assists the driver's steering. The rotational position of the rotor 3 is detected by the resolver 26 and input from the terminal 27 to the control device. The control device switches energization of the coil 16 based on the rotational position of the rotor 4 detected by the resolver 26.

In this embodiment, the first claw portion 62 prevents the plate 21 from rotating relative to the stator housing 11, and the second claw portion 63 prevents the plate 21 from rotating relative to the stator core 12. As a result, since the rotation between the stator core 12 and the stator housing 11 can be prevented via the plate 21, the rotation of the stator core 12 can be reliably prevented as compared with the case where the stator core is fixed to the stator housing only by press-fitting as in the prior art. it can. Since it is not necessary to perform complicated machining on the stator housing 11 and the stator core 12, manufacturing is facilitated and machining costs can be reduced.
Since the plate 21 functions as a receiving tray for the coating material of the coil 16, the coating material does not hang down on the work place. Since the outer periphery of the plate 21 is in close contact with the stator housing 11, the coating material does not hang down on the spigot portion 11A. Improve assembly efficiency and work environment.
Since the plate 21 is manufactured from a magnetic material and disposed between the coil 16 and the resolver 26, the magnetic flux from the coil 16 toward the resolver 26 can be shielded. The resolver 26 is hardly affected by the magnetic flux of the coil 16, and the detection accuracy of the rotational position of the rotor 3 is improved.

Next, a second embodiment of the present invention will be described based on FIGS.
The second embodiment is different from the first embodiment in that the first claw and the second claw are not formed on the plate. In addition, the same code | symbol is attached | subjected to the same member as 1st Embodiment, and description is abbreviate | omitted.

  In the same manner as in the first embodiment, an annular rib 51 is formed on the plate 121 by raising the inner peripheral edge of the ring-shaped disk, and the side wall 52 is formed by raising the outer peripheral edge in the same direction as the rib 51. Is formed. Further, a recess 53 is formed between the rib 51 and the side wall 52.

  Here, a flange portion 154 (anti-rotation portion) is formed at the end of the side wall 52 and extends radially outside the plate 121 and in parallel with the recess 53. The outer diameter of the flange portion 154 is smaller than the outer diameter of the locking portion 61 of the first embodiment, and specifically, is formed approximately equal to the outer diameter of the stator core 12. The inner diameter of the plate 121 and the outer diameter of the side wall 52 are formed in the same manner as in the first embodiment.

  Further, the inner peripheral surface of the stator housing 111 is not formed with the annular groove 42 and the key groove 43 in the first embodiment, but is formed flat until reaching the inlay portion 11A from the opposite side of the release end to which the bracket 4 is fixed. ing. Here, the outer diameter of the flange portion 154 of the plate 121 is preferably formed to be equal to or larger than the inner diameter of the stator housing 111.

  When manufacturing the brushless motor 100 of this embodiment, first, the stator core 12 is formed by combining the core unit around which the coil 16 is wound from the top of the insulator 15 as in the first embodiment.

  Here, the plate 121 is shrink-fitted and fixed inside the stator housing 111. Specifically, the stator housing 111 is heated and expanded to widen the inner diameter, the plate 121 is fitted into the stator housing 111 to return to normal temperature, and both are coupled by contraction of the stator housing 111. As a result, the flange portion 154 of the plate 121 contacts the lower surface of the stator core 12, and the inner peripheral surface of the stator housing 111 contacts the outer peripheral edge 155 of the flange portion 154 without any gap.

  Then, the coil 16 is coated as in the first embodiment. The coating material that has flowed downward along the winding of the coil 16 drops from the lower end of the coil 16 to the recess 53 of the plate 21 as described above. At this time, since the plate 121 and the stator housing 111 are in contact with each other with no gap, the excessive coating material does not flow out to the outside and fills the recess 53 to form the liquid pool 22. When the coating material is dripped sufficiently, the coating material is dried. As a result, the coil 16 is coated, and the plate 121 and the stator housing 111 can be securely bonded by the liquid reservoir 22 filled in the recess 53.

Therefore, according to this embodiment, since the plate 121 functions as a receiving tray for the coating material of the coil 16, the same effect as that of the first embodiment can be obtained.
In addition, since the plate 121 is shrink-fitted and fixed in the stator housing 111, it is not necessary to form the first claws 62 and the second claws 63, and alignment adjustment is also eliminated. Therefore, after the stator core 12 is prevented from rotating with respect to the stator housing 111, the manufacturing becomes easier and the processing cost can be reduced as compared with the first embodiment.

Further, since the flange portion 154 of the plate 121 abuts against the inner peripheral surface of the stator core 12 and the stator housing 111 without any gap, the outflow of the coating material can be prevented more reliably. Further, the plate 121 and the stator housing 11 and the stator core 12 are bonded with a coating material, so that the rotation can be reliably prevented.
Further, since the outer diameter of the flange portion 154 is formed to be substantially equal to the outer diameter of the stator core 12, it does not come into contact with the inlay portion 11A during shrink fitting. Therefore, the plate 121 can be shrink-fitted without damaging the inlay portion 11A.

Note that the present invention can be widely applied without being limited to the above-described embodiment.
For example, the application of the brushless motor 1 is not limited to the power steering device. The rotating shaft is not limited to a hollow shape, and may be solid.
The plate may be manufactured from a material other than a nonmagnetic metal or a metal material. The effect of rotation prevention and liquid pool formation can be obtained. When a coil is formed by using a self-bonding wire, the function of preventing the dripping of the coating material is not required, and when it functions only as a detent, there is no need to provide a recess. In these cases, a plate may be disposed on the side opposite to the resolver.

It is sectional drawing which shows the structure of the brushless motor which concerns on 1st Embodiment of this invention. It is a figure which expands a part of FIG. 1, Comprising: It is a figure which shows the attachment structure of a plate, and the liquid pool of a coating material. It is a perspective view of the stator core which mounted | wore with the plate which concerns on 1st Embodiment of this invention. It is a perspective view of the plate which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the process of coating the coil which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the structure of the brushless motor which concerns on 2nd Embodiment of this invention. It is a figure which expands a part of FIG. 6, Comprising: It is a figure which shows the attachment structure of a plate, and the liquid pool of a coating material. It is a perspective view of the plate which concerns on 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Brushless motor 2 Stator 3 Rotor 11, 111 Stator housing 12 Stator core 15 Insulator 16 Coil 21, 121 Plate 26 Resolver 53 Recessed part 62 1st nail | claw part (anti-rotation part) 63 2nd nail | claw part (anti-rotation part) 154 Flange Part (non-rotating part)

Claims (5)

A brushless motor in which a stator core around which a coil is wound is arranged on the inner periphery of a stator housing, and a rotor is rotatably arranged inside the stator core,
The stator core around which the coil is wound is fixed to the inner periphery of the stator housing, and a plate provided with a detent portion that prevents the stator housing and the stator core from rotating is provided adjacent to the stator core. Brushless motor.   The anti-rotation portion includes a plate formed of a first claw portion that is non-rotatably fitted to the stator housing and a second claw portion that is non-rotatably fitted to the stator core. The brushless motor according to claim 1.   The brushless motor according to claim 1, wherein the rotation preventing portion is a flange portion on an outer peripheral side of the plate that is press-fitted into an inner periphery of the stator housing.   The brushless motor according to any one of claims 1 to 3, wherein the plate has a concave portion capable of forming a liquid pool of the coating material of the coil.   The said plate is manufactured from the magnetic body, and is arrange | positioned between the resolver which detects the rotation position of the said rotor, and the said coil, The Claim 1 characterized by the above-mentioned. Brushless motor.

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