JP2004048821A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide brushless motor where a stator for a resolver is fixed easily without having adverse effect on the detection accuracy of the resolver, and besides a stator for driving is fixed easily. <P>SOLUTION: A coil spring 7 is interposed between the stator 4 for drive and the stator 9 for a resolver, and stators 4 and 9 are fixed, being pressed axially against position regulating projections 2d and 20c provided at a motor case 2 and a cover member 20, respectively. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a brushless motor having a resolver as a detection sensor for detecting a rotational position of a rotor.
[0002]
[Prior art]
In driving the brushless motor, for example, a variable reluctance resolver is used as a rotation angle sensor for obtaining a driving signal. The variable reluctance resolver detects the rotational position (rotation angle) of the rotor by utilizing the fact that the well-known gap permeance formed by the rotor and the stator fluctuates in a sine wave shape with the rotation of the rotor.
[0003]
However, the gap permeance is greatly affected by the dimensional accuracy of each part, the mounting accuracy, and the like, and the detection accuracy is greatly deteriorated particularly when an excessive stress or deformation is caused during assembly. For this reason, when assembling the resolver to the brushless motor, it is important to accurately fix the resolver at a predetermined position. Further, when a stress greater than a predetermined value is applied at the time of assembling and fixing, the detection accuracy may be deteriorated due to generation of strain or the like.
[0004]
For this reason, in fixing, an assembling method and a structure that do not cause the above-described factors are required. As a method of assembling, a method of applying stress such as press fitting cannot be adopted. Therefore, as a method of assembling so as not to apply an excessive stress, a method of tightening and fixing the stator of the resolver to the motor case by screws or caulking has been conventionally used.
[0005]
[Problems to be solved by the invention]
However, in this fixing method, stress is less likely to be applied than in press-fitting, but if the degree of tightening is excessive due to screws or caulking, excessive stress may act as in press-fitting, so it is necessary to adjust the degree of tightening. difficult. In addition, there is a problem that the number of steps is increased in the fastening and fixing method using screws or caulking.
[0006]
In addition, a stator for rotating and driving a brushless motor is conventionally fixed to a motor case by press-fitting or bonding. Therefore, there is a problem that the man-hour for fixing the stator is also required, and the whole man-hour for assembling the brushless motor is large.
[0007]
The present invention has been made in order to solve the above problems, and an object of the present invention is to make it possible to easily fix a resolver stator without adversely affecting the resolver detection accuracy, and to easily form a drive stator. An object of the present invention is to provide a brushless motor that can be fixed.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 detects a substantially annular driving stator that is supplied with a driving voltage and rotates the rotor, and detects a rotational position of the rotor to generate the driving voltage. A substantially annular resolver stator that constitutes a resolver for performing a brushless motor that is inserted and disposed in a case member having an inner diameter that is substantially the same as the outer diameter of each stator; An urging member was interposed between the resolver stator and each of the stators was axially pressed against the position regulating portions provided on the case member by the urging force of the urging member, and was fixed.
[0009]
According to a second aspect of the present invention, in the brushless motor according to the first aspect, the case member includes a substantially cylindrical motor case having a bottom and a lid member attached to an opening of the motor case. The biasing member presses and fixes the driving stator against a position regulating portion provided on one of the motor case and the lid member, and a position where the resolver stator is provided on one of the other. Press and fix against the regulating part.
[0010]
According to a third aspect of the present invention, in the brushless motor according to the first or second aspect, the driving stator and the resolver stator each have a first engagement portion, and the case member has the first engagement portion. Each of the stators has a second engagement portion that engages with the first engagement portion in the circumferential direction.
[0011]
According to a fourth aspect of the present invention, in the brushless motor according to the third aspect, the first engagement portion of each of the stators is a groove formed to extend in an axial direction with respect to an outer peripheral surface of each of the stators. The second engaging portion of the case member is a projection that projects into the groove.
[0012]
According to a fifth aspect of the present invention, in the brushless motor according to any one of the first to fourth aspects, the urging member is a coil spring or a wave washer having an outer diameter substantially equal to the inner diameter of the case member. .
[0013]
According to a sixth aspect of the present invention, in the brushless motor according to any one of the first to fifth aspects, at least a surface of the urging member that is in contact with the resolver stator is a flat surface.
[0014]
(Action)
According to the first aspect of the present invention, the urging member is interposed between the driving stator and the resolver stator, and each of the stators is provided on the position regulating portion provided on the case member by the urging force of the urging member. It is pressed in the axial direction and fixed. That is, the biasing force of the biasing member does not exert an excessive stress on the resolver stator that adversely affects the resolver detection accuracy. Therefore, it is possible to easily fix the resolver stator by simply biasing the resolver stator with the biasing member. it can. Further, since the urging member is interposed between the resolver stator and the driving stator, the driving stator can be easily fixed together with the resolver stator.
[0015]
According to the invention described in claim 2, the case member includes a substantially cylindrical motor case having a bottom and a lid member attached to the opening of the motor case, and is driven by the urging force of the urging member. The stator is pressed and fixed to a position restricting portion provided on one of the motor case and the lid member, and the resolver stator is pressed and fixed against a position restricting portion provided on one of the other. You. That is, the motor is inserted until the driving stator (or the resolver stator) comes into contact with the position regulating portion of the motor case, then the biasing member is inserted, and then the resolver stator (or the driving stator). And the lid is attached to the opening of the case, so that the motor can be easily assembled.
[0016]
According to the invention described in claim 3, the driving stator and the resolver stator are each provided with the first engagement portion, and the case member is provided with the first engagement portion of each stator in the circumferential direction. A second engaging portion to be engaged is provided. Thus, it is possible to reliably prevent each stator from being displaced in the circumferential direction with respect to the case member.
[0017]
According to the invention described in claim 4, the first engagement portion of each stator is a groove formed to extend in the axial direction with respect to the outer peripheral surface of each stator, and the second engagement portion of the case member. Are projections projecting into the groove. That is, since the shape of each engagement portion is simple, each engagement portion can be easily formed.
[0018]
According to the fifth aspect of the present invention, the biasing member is a coil spring or a wave washer having an outer diameter substantially equal to the inner diameter of the case member. Thereby, each stator can be fixed by one urging member. Further, the displacement of the coil spring or the wave washer can be prevented without using a special member.
[0019]
According to the invention described in claim 6, the biasing member has at least a plane that comes into contact with the resolver stator in a plane. Therefore, it is possible to prevent the stress from the urging member from being concentrated on the resolver stator. That is, if deformation or distortion occurs due to stress being concentrated on the resolver stator, the detection accuracy of the resolver may be degraded, so that the detection accuracy is reliably prevented from deteriorating.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a brushless motor 1 of the present embodiment. The brushless motor 1 has a substantially bottomed cylindrical motor case 2 constituting a case member. A bearing holding portion 2b is formed at the center of the bottom 2a of the motor case 2, and a ball bearing 3 is attached to the holding portion 2b. The ball bearing 3 rotatably supports a base end of a rotating shaft 16 described later.
[0021]
A substantially annular driving stator 4 for rotating and driving the brushless motor 1 (rotor 15) is disposed near the bottom 2a of the motor case 2.
The driving stator 4 includes a substantially annular stator core 5 and a winding 6. The stator core 5 has an annular outer edge 5a and a plurality of teeth 5b connected to the outer edge 5a and arranged in the circumferential direction and each extending in the center direction. The winding 6 is wound around the teeth 5b. By turning, the driving stator 4 is formed. The outer diameter of the driving stator 4 (stator core 5) is set to a size that allows the stator 4 to move inside the motor case 2 and to be substantially the same as the inner diameter of the case 2. The driving stator 4 is inserted from the opening 2c of the motor case 2 to a predetermined position on the bottom 2a.
[0022]
A plurality of position regulating protrusions 2d (only two are shown in FIG. 1) as a plurality of position regulating parts arranged at equal intervals in the circumferential direction are formed on the inner peripheral surface of a predetermined portion near the bottom 2a of the motor case 2. Have been. Each position regulating protrusion 2d is formed by, for example, stamping out from the outside of the motor case 2 to the inside. The position restricting projection 2d restricts the further movement of the driving stator 4 in the insertion direction (the bottom 2a side) and positions the driving stator 4.
[0023]
On the inner peripheral surface of the motor case 2 on which the driving stator 4 is disposed, a rotation preventing protrusion 2e is formed as a protrusion. The rotation prevention protrusion 2e is formed by, for example, stamping out from the outside of the motor case 2 to the inside. On the other hand, on the outer peripheral surface of the stator core 5 of the driving stator 4, an axially extending first engaging portion and an engaging groove 5c as a groove are formed. When the driving stator 4 is inserted, the stator 4 is inserted so that the anti-rotation protrusion 2e protrudes into the engagement groove 5c, and the engagement groove 5c and the anti-rotation protrusion 2e are aligned in the circumferential direction. The engagement prevents the stator 4 from rotating.
[0024]
A coil spring 7 as an urging member is interposed between the driving stator 4 and a resolver stator 9 described later. The coil spring 7 is formed in a spiral shape having an outer diameter substantially equal to the inner diameter of the motor case 2 using a wire having a circular cross section. The coil spring 7 is inserted after the driving stator 4 is inserted into the motor case 2. Then, the coil spring 7 presses the stators 4 and 9 with a predetermined urging force in a direction in which the stators 4 and 9 are separated from each other in the axial direction. That is, by the urging force of the coil spring 7, the driving stator 4 is pressed against and fixed to the position regulating protrusion 2d of the motor case 2 by a predetermined pressing force, and the resolver stator 9 is fixed to the position regulating protrusion of the lid member 20 described later. 20c is pressed and fixed with a predetermined pressing force. Incidentally, the urging force of the coil spring 7 presses both the stators 4 and 9 in order to prevent rattling of the stators 4 and 9 and prevents an excessive stress that adversely affects the detection accuracy of the resolver 8 from occurring. The size is set such that the resolver stator 9 is pressed.
[0025]
A resolver stator 9 constituting a resolver 8 for detecting the rotational position of the rotor 15 of the brushless motor 1 is disposed near the opening 2c of the motor case 2.
[0026]
The resolver stator 9 includes a substantially annular stator core 10 and a winding 11. The stator core 10 includes an annular outer edge portion 10a, and a plurality of circumferentially arranged teeth portions 10b connected to the outer edge portion 10a and each extending in the center direction. The winding 11 is wound around the teeth portion 10b. By turning, the resolver stator 9 is configured. The outer diameter of the resolver stator 9 (stator core 10) is set to a size that allows the stator 9 to move inside the motor case 2 and to be substantially the same as the inner diameter of the case 2. The resolver stator 9 is inserted from the opening 2 c of the motor case 2 after the coil spring 7 is inserted.
[0027]
On the inner peripheral surface of the motor case 2 where the resolver stator 9 is arranged, a rotation preventing protrusion 2f is formed as a protrusion. The rotation prevention protrusion 2f is formed by, for example, stamping out from the outside of the motor case 2 to the inside. On the other hand, on the outer peripheral surface of the stator core 10 of the resolver stator 9, an axially extending first engaging portion and an engaging groove 10c as a groove are formed. When the resolver stator 9 is inserted, the stator 9 is inserted so that the anti-rotation protrusion 2f protrudes into the engagement groove 10c, and the engagement groove 10c and the anti-rotation protrusion 2f are aligned in the circumferential direction. The engagement prevents the stator 9 from rotating.
[0028]
A rotor 15 is rotatably accommodated inside the driving stator 4 and the resolver stator 9.
The rotor 15 includes a rotating shaft 16, and a driving rotor unit 17 and a resolver rotor unit 18 fixed at predetermined positions on the rotating shaft 16, respectively. The rotation shaft 16 has a base end rotatably supported by a ball bearing 3 provided on the motor case 2, and a predetermined portion near the front end is rotatable by a ball bearing 22 provided on a lid member 20 described later. Supported.
[0029]
The driving rotor unit 17 has a cylindrical rotor core 17a fixed to the rotating shaft 16, and a plurality of magnets 17b fixed to the outer peripheral surface of the rotor core 17a. The driving rotor section 17 is fixed to the rotating shaft 16 such that the magnet 17b faces the driving stator 4 in the radial direction.
[0030]
The resolver rotor section 18 has a substantially cylindrical shape, and has a plurality of salient pole sections 18a at equal intervals in the circumferential direction on the outer peripheral surface. The resolver rotor section 18 is fixed to the rotating shaft 16 such that the salient pole section 18a faces the resolver stator 9 in the radial direction. When the rotor 18 having such salient poles 18a rotates, the gap permeance formed by the rotor 18 and the resolver stator 9 fluctuates sinusoidally. That is, the variable reluctance resolver 8 for detecting the rotation position of the rotor 15 of the brushless motor 1 is constituted by the resolver rotor section 18 and the resolver stator 9.
[0031]
A disc-shaped lid member 20 that forms a case member and closes the opening 2c is attached to the opening 2c of the motor case 2. After inserting the driving stator 4, the coil spring 7, the resolver stator 9, and the rotor 15 into the motor case 2, the cover member 20 is tightened with a plurality of mounting pieces 2 g provided in the opening 2 c of the case 2 and screws 21. Fixed. A bearing holding portion 20a is formed at the center of the lid member 20, and a ball bearing 22 is attached to the holding portion 20a. The ball bearing 22 rotatably supports a predetermined portion near the tip of the rotating shaft 16. An insertion hole 20b is formed at the center of the lid member 20, and the tip of the rotating shaft 16 projects from the insertion hole 20b. In addition, on the inner peripheral edge of the lid member 20, there are position regulating protrusions 20c (only two are shown in FIG. 1) as a plurality of position regulating parts that contact the resolver stator 9 arranged at equal intervals in the circumferential direction. ) Is protruding. The position restricting projection 20c restricts the further movement of the resolver stator 9 in the direction opposite to the insertion direction (on the side of the lid member 20), and positions the resolver stator 9.
[0032]
In the brushless motor 1 configured as described above, a sine-wave drive voltage is supplied to the drive stator 4 from a drive circuit (not shown), and the rotor 15 rotates. Also, at this time, the fact that the gap permeance of the resolver 8 composed of the resolver rotor section 18 and the resolver stator 9 fluctuates in a sine wave shape with the rotation of the rotor 15 (rotor section 18) is utilized. The rotation position (rotation angle) is detected. Then, a sine-wave drive voltage is generated by the drive circuit based on the rotational position of the rotor 15 detected by the resolver 8, supplied to the drive stator 4, and the rotation of the rotor 15 is continued.
[0033]
The brushless motor 1 of the present embodiment has the following features.
(1) In the present embodiment, the coil spring 7 is interposed between the driving stator 4 and the resolver stator 9, and the respective stators 4 and 9 are provided on the motor case 2 and the lid member 20 by the urging force of the coil spring 7. Are pressed in the axial direction and fixed to the position regulating protrusions 2d and 20c. That is, since the biasing force of the coil spring 7 does not exert an excessive stress on the resolver stator 9 that adversely affects the detection accuracy of the resolver 8, the stator 9 for the resolver can be easily fixed only by biasing the stator 9 with the coil spring 7. Can be. Further, since the coil spring 7 is interposed between the resolver stator 9 and the drive stator 4, the drive stator 4 can be easily fixed together with the resolver stator 9.
[0034]
(2) In the present embodiment, the driving stator 4 is inserted until it comes into contact with the position regulating protrusion 2d of the motor case 2, then the coil spring 7 is inserted, and then the resolver stator 9 is inserted. The brushless motor 1 is assembled by attaching the lid member 20 to the opening 2c. Therefore, the motor 1 can be easily assembled.
[0035]
(3) In the present embodiment, the engaging grooves 5c and 10c are formed in the outer peripheral surfaces of the driving stator 4 and the resolver stator 9 so as to extend in the axial direction, respectively, and the engaging grooves 5c and 10c are formed in the motor case 2. Are formed with anti-rotation protrusions 2e and 2f, respectively. Accordingly, since the engagement grooves 5c and 10c and the rotation preventing protrusions 2e and 2f engage in the circumferential direction, it is possible to reliably prevent the stators 4 and 9 from being displaced in the circumferential direction with respect to the motor case 2. Can be. Further, since the engagement grooves 5c and 10c and the rotation preventing protrusions 2e and 2f have simple shapes, they can be easily formed.
[0036]
(4) In the present embodiment, since the coil springs 7 having substantially the same outer diameter as the inner diameter of the motor case 2 are used, each of the stators 4 and 9 can be fixed by one coil spring 7. Further, the displacement of the coil spring 7 can be prevented without using a special member.
[0037]
Note that the embodiment of the present invention may be modified as follows.
In the above embodiment, as the urging member for urging each of the stators 4 and 9, the coil spring 7 formed in a spiral shape having an outer diameter substantially equal to the inner diameter of the motor case 2 using a wire having a circular cross section is used. However, the present invention is not limited to this.
[0038]
For example, as in a brushless motor 1 a shown in FIG. 2, a coil spring 25 formed by using a wire having a rectangular cross section and having a spiral shape having an outer diameter substantially equal to the inner diameter of the motor case 2 may be used. In the coil spring 25, the contact surfaces 25a and 25b that contact the resolver stator 9 and the drive stator 4 are flat. Therefore, it is possible to prevent the stress from the coil spring 25 from being concentrated on the resolver stator 9. That is, if deformation or distortion occurs due to stress being concentrated on the resolver stator 9, the detection accuracy of the resolver 8 may be deteriorated, so that the detection accuracy is reliably prevented from being deteriorated. In this case, at least the surface 25a of the coil spring 25 that comes into contact with the resolver stator 9 may be a flat surface.
[0039]
Further, as in the brushless motor 1b shown in FIG. 3, a wave washer 26 formed in a circumferential direction by using a wire having a rectangular cross section and having an outer diameter substantially equal to the inner diameter of the motor case 2 may be used. . Also in this wave washer 26, since the contact surfaces 26a and 26b that contact the resolver stator 9 and the drive stator 4 are flat, the same effect as described above can be obtained. The wave washer 26 may be formed of a wire having a cross-sectional shape other than a rectangular cross-section.
[0040]
Also, as in the brushless motor 1c shown in FIG. 4, three coil springs 27 may be used at equal intervals in the circumferential direction (only two are shown in FIG. 4). These coil springs 27 are fixed to the lid member 20 and are inserted into and supported by rods 28 inserted into the insertion holes 5d and 10d provided in the stators 4 and 9, respectively. Therefore, the movement of the coil spring 27 is prevented by the bar 28. In addition, the movement of the stators 4 and 9 in the circumferential direction is restricted by the bar 28. Therefore, it is possible to omit the engagement grooves 5c and 10c and the rotation prevention protrusions 2e and 2f of the above embodiment. The number of the coil springs 27 is not limited to this.
[0041]
Further, an urging member other than those shown in FIGS. 2 to 4 may be used. Further, the biasing member may be constituted by a member having elasticity such as rubber.
In the above embodiment, the engagement grooves 5c, 10c extending in the axial direction are formed on the outer peripheral surface of each of the stators 4, 9 as means for circumferentially engaging each of the stators 4, 9 with the motor case 2. Although the rotation preventing protrusions 2e and 2f are formed on the case 2, the engaging portions may have other configurations (shape, number, position, etc.). For example, a protrusion may be formed on each of the stators 4 and 9, and a groove extending in the axial direction may be formed on the inner peripheral surface of the motor case 2. Further, an engagement portion that engages with each of the stators 4 and 9 may be formed on the lid member 20. Further, the anti-rotation protrusions 2e and 2f are formed by stamping out from the outside to the inside of the motor case 2, but may be formed by other methods. If the stators 4 and 9 are not displaced in the rotational direction by the coil spring 7, these engaging portions may be omitted.
[0042]
In the above embodiment, the motor case 2 and the lid member 20 are provided with the position regulating protrusions 2d and 20c for regulating the position of each of the stators 4 and 9 in the axial direction. However, the shape, number, and position of these position regulating protrusions 2d and 20c are provided. May be appropriately changed. For example, although the position regulating protrusions 2d and 20c are provided at equal intervals in the circumferential direction, they may be provided annularly in the circumferential direction. Further, although the position regulating protrusion 2d provided on the motor case 2 is formed by stamping out from the outside of the case 2 to the inside, it may be formed by other methods.
[0043]
In the above-described embodiment, the case member of the brushless motor 1 is constituted by the substantially bottomed cylindrical motor case 2 and the disc-shaped lid member 20 attached to the opening 2c of the case 2; Is not limited to this, and may be changed as appropriate. For example, a configuration may be adopted in which the motor case has a cylindrical shape with both ends opened in the axial direction, and lid members are attached to both openings.
[0044]
The configuration of the brushless motor 1 of the above embodiment may be appropriately changed other than the above.
[0045]
【The invention's effect】
As described above in detail, according to the present invention, there is provided a brushless motor in which a resolver stator can be easily fixed without adversely affecting resolver detection accuracy, and a drive stator can also be easily fixed. be able to.
[Brief description of the drawings]
FIG. 1 is a sectional view of a brushless motor according to an embodiment.
FIG. 2 is a cross-sectional view of another example of a brushless motor.
FIG. 3 is a cross-sectional view of another example of a brushless motor.
FIG. 4 is a cross-sectional view of another example of a brushless motor.
[Explanation of symbols]
Reference numeral 2 denotes a motor case constituting a case member, 2d denotes a position restricting projection as a position restricting portion, 2e and 2f ... a rotation preventing projection as a second engaging portion and a projection, 4 ... a driving stator, and 5c ... a first engaging. Engaging groove as part and groove, 7 ... Coil spring as urging member, 8 ... Resolver, 9 ... Resolver stator, 10c ... Engaging groove as first engaging part and groove, 15 ... Rotor, 20 ... Case A cover member constituting a member, 20c a position regulating protrusion as a position regulating portion, 25 a coil spring as a biasing member, 25a a contact surface as a surface, 26 a wave washer as a biasing member, 26a as a surface , A coil spring as an urging member.

Claims (6)

A substantially annular drive stator that is supplied with a drive voltage to rotate the rotor, and a substantially annular resolver stator that constitutes a resolver for detecting a rotational position of the rotor to generate the drive voltage, A brushless motor inserted and disposed in a case member having substantially the same inner diameter as the outer diameter of each stator, wherein an urging member is interposed between the driving stator and the resolver stator, A brushless motor, wherein each of the stators is axially pressed and fixed to a position regulating portion provided on the case member by an urging force of an urging member. The brushless motor according to claim 1,
The case member includes a substantially bottomed cylindrical motor case, and a lid member attached to an opening of the motor case,
The biasing member presses and fixes the driving stator against a position regulating portion provided on one of the motor case and the lid member, and the resolver stator is provided on one of the other. A brushless motor characterized in that the brushless motor is pressed against and fixed to a position regulating portion. The brushless motor according to claim 1 or 2,
The drive stator and the resolver stator each have a first engagement portion,
The brushless motor according to claim 1, wherein the case member has a second engaging portion that engages with the first engaging portion of each of the stators in a circumferential direction. The brushless motor according to claim 3,
The first engagement portion of each stator is a groove formed to extend in the axial direction with respect to the outer peripheral surface of each stator,
The brushless motor according to claim 1, wherein the second engagement portion of the case member is a projection that projects into the groove. The brushless motor according to any one of claims 1 to 4,
The brushless motor according to claim 1, wherein the urging member is a coil spring or a wave washer having an outer diameter substantially equal to an inner diameter of the case member. The brushless motor according to any one of claims 1 to 5,
The brushless motor according to claim 1, wherein the urging member has a flat surface at least in contact with the resolver stator.

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