JP2004064801A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor capable of attaining size reduction in the axial direction. <P>SOLUTION: A bearing 30 rotatably supporting a resolver stator 26 and a rotor 15 forming a rotation sensor is held by an accommodating and holding portion 20b formed recessed in a covering member 20 for covering an opening portion 2b of a motor case 2. The accommodating and holding portion 20b is inserted so as to accommodate nearly the entire portion of the bearing 30 in a hollow portion 18b having an opening 18a axially formed on a driving rotor 17 (a rotor core 18). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a brushless motor having 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 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]
FIG. 3 shows a conventional brushless motor equipped with such a rotation sensor (resolver). The brushless motor 51 has a substantially bottomed cylindrical motor case 52. A driving stator 53 for rotating and driving the brushless motor 51 (rotor 60) is fixed to the inner peripheral surface of the motor case 52. The driving stator 53 is configured by winding a winding 55 around a stator core 54. A power supply section 56 for supplying a sine-wave drive voltage from a drive circuit (not shown) to the stator 53 (winding 55) is provided at a position closer to the opening 52a than the driving stator 53 of the motor case 52. A ball bearing 57 is fixed at the center of the bottom 52b of the motor case 52.
[0004]
A rotor 60 is rotatably housed inside the driving stator 53. The rotor 60 has a rotating shaft 61, and the base end of the rotating shaft 61 is rotatably supported by the ball bearing 57. At a predetermined position near the base end of the rotating shaft 61, a driving rotor portion 62 is fixed so as to face the driving stator 53 in the radial direction. The driving rotor unit 62 is configured such that a plurality of magnets 64 are fixed to an outer peripheral surface of a rotor core 63 fixed to the rotating shaft 61.
[0005]
A frame end 65 for closing the opening 52a is attached to the opening 52a of the motor case 52. A resolver stator 71 constituting a resolver 70 for detecting the rotational position of the rotor 60 of the brushless motor 51 is fixed to the frame end 65 with a screw 72. The resolver stator 71 is configured by winding a winding 74 around a stator core 73. On the other hand, a resolver rotor unit 75 is fixed to a substantially center of the rotation shaft 61 in the axial direction so as to face the resolver stator 71 in the radial direction. The resolver rotor section 75 and the resolver stator 71 constitute a variable reluctance resolver 70.
[0006]
A ball bearing 76 is fixed to the center of the frame end 65, and a predetermined portion near the tip of the rotating shaft 61 is rotatably supported by the bearing 76. The rotating shaft 61 projects outside from the frame end 65. ing.
[0007]
In such a brushless motor 51, when a sine-wave driving voltage is supplied from the power supply unit 56 to the driving stator 53, a rotating magnetic field is generated in the stator 53, and the rotor 60 rotates. At this time, utilizing the fact that the gap permeance of the resolver 70 composed of the resolver rotor section 75 and the resolver stator 71 fluctuates in a sine wave shape with the rotation of the rotor 60 (rotor section 75), the rotational position of the rotor 60 (Rotation angle) is detected. A drive circuit generates a sine-wave drive voltage based on the rotational position of the rotor 60 detected by the resolver 70, and the sine-wave drive voltage is supplied to the drive stator 53.
[0008]
[Problems to be solved by the invention]
However, the above-described brushless motor 51 has a configuration in which a ball bearing 57, a driving stator 53, a power supply unit 56, a resolver 70, and a ball bearing 76 are arranged in series from the base end in the axial direction to the tip end. Therefore, there is a problem that the brushless motor 51 becomes longer in the axial direction.
[0009]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a brushless motor that can be downsized in the axial direction.
[0010]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 supplies a drive voltage to a drive stator to rotate a rotor disposed inside the drive stator and generate the drive voltage. A brushless motor provided with a rotation sensor for detecting a rotation position of the rotor, wherein the rotor has a driving rotor unit corresponding to the driving stator and a sensor rotor unit constituting the rotation sensor. A sensor stator corresponding to the sensor rotor unit and a bearing rotatably supporting the rotor are held by a housing holder recessed in a lid member for closing an opening of a motor case. A hollow portion having an opening in the axial direction is formed in the driving rotor portion, and a part of at least one of the bearing and the rotation sensor is formed in the hollow portion. Housing holding portion of the lid member is inserted to accommodate the whole.
[0011]
According to a second aspect of the present invention, in the brushless motor according to the first aspect, a sensor connector for outputting a detection signal from the rotation sensor is provided in the opening of the holding portion of the lid member. It is provided so as to close the opening of the part.
[0012]
According to a third aspect of the present invention, in the brushless motor according to the second aspect, the opening of the sensor connector is directed outward in the axial direction such that the connection direction with the external connector is substantially axial. It is configured.
[0013]
According to a fourth aspect of the present invention, there is provided the brushless motor according to any one of the first to third aspects, wherein a wiring board is inserted into an insulating portion to supply the driving voltage to the driving stator. Is disposed on the side of the lid member of the stator, and the wiring member is formed in an annular shape so as to be located radially outward of the holding portion of the lid member.
[0014]
According to a fifth aspect of the present invention, in the brushless motor according to the fourth aspect, the wiring member and the driving stator are pressed and fixed to the motor case between the wiring member and the lid member. The urging member is formed in an annular shape so as to be located radially outside the holding portion of the lid member.
[0015]
According to a sixth aspect of the present invention, in the brushless motor according to any one of the first to fifth aspects, the lid member is formed of a metal plate.
According to a seventh aspect of the present invention, in the brushless motor according to any one of the first to sixth aspects, the rotation sensor is a resolver.
[0016]
(Action)
According to the first aspect of the present invention, the bearing for rotatably supporting the stator for the sensor and the rotor constituting the rotation sensor is a housing holding portion recessed in the lid member for closing the opening of the motor case. The housing holding portion is inserted into a hollow portion provided in the driving rotor portion and having an opening in the axial direction so as to house at least one part and all of the bearing and the rotation sensor. Therefore, the member accommodated in the hollow portion of the driving rotor portion overlaps the rotor portion in the axial direction, so that the brushless motor is moved in the axial direction by an axial length corresponding to a part or all of the accommodated member. Can be downsized.
[0017]
According to the second aspect of the present invention, a sensor connector for outputting a detection signal from a rotation sensor is provided at the opening of the holding portion of the lid member so as to close the opening of the holding portion. Can be Therefore, since the sensor connector also functions as a lid for closing the opening of the holding portion, the number of components is reduced.
[0018]
According to the third aspect of the present invention, the sensor connector is configured such that its opening is directed outward in the axial direction so that the connection direction with the external connector is substantially axial.
Therefore, the amount of protrusion of the sensor connector in the axial direction can be suppressed, and the size of the motor can be reduced in the axial direction.
[0019]
According to the invention as set forth in claim 4, a wiring member obtained by inserting a wiring board into an insulating portion to supply a driving voltage to the driving stator is disposed on the lid member side of the stator. The wiring member is formed in an annular shape so as to be located radially outside the holding portion of the lid member. Therefore, since the wiring member and the housing holding portion of the lid member do not interfere in the axial direction, the motor can be downsized in the axial direction.
[0020]
According to the fifth aspect of the present invention, an urging member for pressing and fixing the wiring member and the driving stator to the motor case is provided between the wiring member and the lid member. The biasing member is formed in an annular shape so as to be positioned radially outside the holding portion of the lid member. Therefore, the biasing member and the holding portion of the lid member do not interfere with each other in the axial direction, so that the motor can be downsized in the axial direction.
[0021]
According to the invention described in claim 6, the rotation sensor housed in the housing holding portion of the lid member is shielded from the driving stator by the lid member. Therefore, by forming such a lid member with a metal plate, electromagnetic noise generated in the driving stator is shielded by the lid member, so that adverse effects of the electromagnetic noise on the rotation sensor can be reduced. Therefore, the detection accuracy of the rotation sensor increases.
[0022]
According to the invention described in claim 7, the rotation sensor is a resolver, and the brushless motor provided with the resolver can be downsized in the axial direction.
[0023]
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. A positioning step 2a is formed on the inner peripheral surface of the motor case 2, and a substantially annular driving stator 3 for rotating and driving the brushless motor 1 (rotor 15) is brought into contact with the step 2a. Has been inserted. The driving stator 3 includes a substantially annular stator core 4 and a winding 5 wound around the stator core 4.
[0024]
An annular wiring member 6 is attached to the axial base end 3a of the driving stator 3. The wiring member 6 is formed by integrally forming a wiring board 8 made of a metal plate on an insulating portion 7 made of resin. The wiring member 6 is mounted on the driving stator 3, and the wiring board 8 is electrically connected to the winding 5 of the stator 3. The wiring board 8 of the wiring member 6 is electrically connected to a terminal 10 inserted in a power supply connector 9 for receiving power supply from the outside. The power supply connector 9 is fitted in a connector fitting portion 2c provided in the opening 2b of the motor case 2, and is sandwiched between the motor case 2 and a lid member 20 described later. The power supply connector 9 has an opening 9a facing outward in the radial direction, and the connection direction with an external connector (not shown) is set in the radial direction.
[0025]
In the center of the bottom 2d of the motor case 2, a bearing holding portion 2e is formed. A ball bearing 11 that rotatably supports a predetermined portion near the tip of the rotating shaft 16 is fixed to the bearing holding portion 2e.
[0026]
A rotor 15 is rotatably accommodated inside the driving stator 3. The rotor 15 has a rotating shaft 16, and a predetermined portion near the tip of the rotating shaft 16 is rotatably supported by the ball bearing 11. The rotating shaft 16 protrudes from the bearing holder 2e to the outside of the motor case 2.
[0027]
At substantially the center of the rotating shaft 16 in the axial direction, a driving rotor portion 17 is provided so as to radially oppose the driving stator 3. The driving rotor unit 17 includes a substantially cylindrical rotor core unit 18 formed integrally with the rotating shaft 16, and a plurality of magnets 19 fixed to the outer peripheral surface of the rotor core unit 18. The rotor core portion 18 is formed with a hollow portion 18b having an opening 18a on the base end side in the axial direction.
[0028]
A cover member 20 having a predetermined shape is attached to the opening 2b of the motor case 2 by a screw 21 so as to close the opening 2b. The cover member 20 is formed by pressing a metal plate material such as iron. The cover member 20 includes a substantially annular annular end surface portion 20a that contacts the opening 2b of the motor case 2 and an inner periphery of the annular end surface portion 20a. And an accommodation holding portion 20b which is recessed in a substantially cylindrical shape on the inside in the axial direction (on the bottom 2d side). The housing holder 20b is formed with a resolver holder 20c extending from the opening 2b side of the motor case 2 to a position near the driving rotor unit 17.
[0029]
The resolver holder 20c houses a resolver 25 as a rotation sensor that detects the rotation position of the rotor 15 of the brushless motor 1. The resolver 25 includes a resolver stator 26 as a sensor stator and a resolver rotor 27 as a sensor rotor provided in the rotor 15. The resolver stator 26 includes a substantially annular stator core 28 formed by laminating plate-shaped stator core members in the axial direction, and windings 29 wound around the stator core 28. The resolver stator 26 (stator core 28) is inserted into the holding portion 20c until it contacts the positioning protrusion 20d formed on the inner peripheral surface of the resolver holding portion 20c. Further, the resolver stator 26 (stator core 28) is engaged with a rotation restricting ridge 20e that is formed to extend in the axial direction on the inner peripheral surface of the resolver holding portion 20c, thereby preventing the positional deviation in the rotational direction.
[0030]
On the other hand, the resolver rotor section 27 is fixed to the base end of the rotating shaft 16 that protrudes into the accommodation holding section 20b so as to face the resolver stator 26 in the radial direction. The resolver rotor section 27 is formed by laminating plate-shaped rotor core members in the axial direction. The resolver rotor section 27 and the resolver stator 26 constitute a variable reluctance resolver 25 for detecting the rotational position of the rotor 15 of the brushless motor 1.
[0031]
The housing holder 20b extends from the resolver holder 20c further to the bottom 2d side of the motor case 2 and is substantially entirely inserted into a hollow part 18b provided in the driving rotor part 17 (rotor core part 18). The bearing holding portion 20f is formed. The bearing holding portion 20f holds a metal bearing 30 as a bearing that rotatably supports a predetermined portion (a portion between the driving-side rotor portion 17 and the resolver rotor portion 27) near the base end portion of the rotating shaft 16. You.
[0032]
The base end portion 3a in the axial direction of the driving stator 3, the annular end surface portion 20a of the lid member 20, the outer peripheral surface 20g of the housing holder 20b, and the inner peripheral surface 2f of the motor case 2 form a substantially annular shape. An annular housing 35 is formed. The wiring member 6 mounted on the driving stator 3 is disposed in the annular housing portion 35. A disc spring 36 as a substantially annular urging member is accommodated in an annular accommodating portion 35 between the axial base end portion 6a of the wiring member 6 and the annular end surface portion 20a of the lid member 20. . When the lid member 20 is attached, the disc spring 36 is elastically deformed so as to generate an urging force in the axial direction. That is, since one end of the disc spring 36 is regulated by the lid member 20 (annular end face portion 20a), the urging force presses the wiring member 6 toward the driving stator 3 to position the stator 3 in the motor case 2. To the step 2a. That is, the disc spring 36 is provided for pressing and fixing the driving stator 3 and the wiring member 6 to the motor case 2.
[0033]
A resolver connector 37 as a sensor connector for outputting a detection signal from the resolver 25 is attached to the opening 20h of the housing holder 20b of the lid member 20. The resolver connector 37 also serves as a lid for closing the opening 20h. A terminal 38 is inserted into the resolver connector 37, and the terminal 38 is electrically connected to the winding 29 of the resolver stator 26. The resolver connector 37 has an opening 37a facing outward in the axial direction, and the connection direction with an external connector (not shown) is set in the axial direction.
The resolver connector 37 abuts against the resolver stator 26 and is axially held between the resolver stator 26 and the positioning projection 20d of the holding portion 20c, thereby fixing the stator 26.
[0034]
In the brushless motor 1 configured as described above, a sine wave drive voltage is supplied to the drive stator 3 from a drive circuit (not shown) via the power supply connector 9 and the wiring member 6, and the stator 3 generates a rotating magnetic field. , The rotor 15 rotates. Also, at this time, the fact that the gap permeance formed by the resolver rotor portion 27 and the resolver stator 26 in the resolver 25 fluctuates in a sine wave shape with the rotation of the rotor 15 (rotor portion 27) is utilized. The rotation position (rotation angle) is detected. The detection signal is output to the drive circuit via the resolver connector 37. A drive circuit generates a sine-wave drive voltage based on the rotational position of the rotor 15 detected by the resolver 25, and the sine-wave drive voltage is supplied to the drive stator 3.
[0035]
The brushless motor 1 of the present embodiment has the following features.
(1) The resolver stator 26 and the bearing 30 that rotatably support the rotor 15 constituting the rotation sensor are provided on the housing holding portion 20b recessed in the lid member 20 for closing the opening 2b of the motor case 2. Is held. The holding portion 20b is inserted into a hollow portion 18b provided in the driving rotor portion 17 (rotor core portion 18) and having an opening 18a in the axial direction so as to receive substantially the entire bearing 30. Accordingly, the bearing 30 accommodated in the hollow portion 18b of the driving rotor portion 17 overlaps the rotor portion 17 in the axial direction, so that the brushless motor has an axial length corresponding to the accommodated portion of the bearing 30. 1 can be reduced in the axial direction.
[0036]
(2) A resolver connector 37 for outputting a detection signal from the resolver 25 serving as a rotation sensor closes the opening 20h of the holding portion 20b in the opening 20h of the holding portion 20b of the lid member 20. It is provided in. Therefore, since the resolver connector 37 also functions as a lid that closes the opening 20h of the housing holder 20b, the number of components can be reduced.
[0037]
(3) The resolver connector 37 is configured such that the opening 37a is directed outward in the axial direction so that the connection direction with the external connector is substantially axial. Therefore, the amount of protrusion of the resolver connector 37 in the axial direction can be suppressed, and the size of the motor 1 can be reduced in the axial direction.
[0038]
(4) A wiring member 6 in which a wiring board 8 is inserted into the insulating portion 7 to supply a driving voltage to the driving stator 3 is disposed on the lid member 20 side of the stator 3. The cover member 20 is formed in an annular shape so as to be positioned radially outside of the holding portion 20 b of the cover member 20. Therefore, since the wiring member 6 and the holding portion 20b of the lid member 20 do not interfere in the axial direction, the size of the motor 1 can be reduced in the axial direction.
[0039]
(5) A disc spring 36 for pressing and fixing the wiring member 6 and the driving stator 3 to the motor case 2 is provided between the wiring member 6 and the lid member 20. Is formed in an annular shape so as to be located radially outward of the holding portion 20b of the lid member 20. Accordingly, since the disc spring 36 and the holding portion 20b of the lid member 20 do not interfere in the axial direction, the size of the motor 1 can be reduced in the axial direction.
[0040]
(6) The resolver 25 as a rotation sensor housed in the housing holder 20 b of the lid member 20 is shielded from the driving stator 3 by the lid member 20. Therefore, by forming such a cover member 20 with a metal plate, the electromagnetic noise generated in the driving stator 3 is shielded by the cover member 20, thereby reducing the adverse effect of the electromagnetic noise on the resolver 25. can do. Therefore, the detection accuracy of the resolver 25 can be improved.
[0041]
Note that the embodiment of the present invention may be modified as follows.
In the above embodiment, in order to reduce the size of the brushless motor 1 in the axial direction, the holding portion 20b that holds the metal bearing 30 in the hollow portion 18b of the driving rotor portion 17 so as to receive substantially the entire bearing 30. (Bearing holding portion 20f) is inserted, but is not limited to this.
[0042]
For example, as shown in the brushless motor 1a of FIG. 2, the entire ball bearing 40 as a bearing is completely accommodated in the hollow portion 18b of the driving rotor portion 17, and a part of the resolver 25 is also placed in the hollow portion 18b. You may make it insert the accommodation holding part 20b so that it may accommodate. By doing so, the motor 1a can be further miniaturized in the axial direction by an axial length corresponding to a part of the ball bearing 40 and the resolver 25 housed in the hollow portion 18b.
[0043]
Further, with this configuration, most of the resolver connector 37 can be accommodated in the accommodation holding portion 20b, so that the amount of axial protrusion of the connector 37 can be further reduced. This also makes it possible to further reduce the size of the brushless motor 1a in the axial direction.
[0044]
Further, the entire bearing 30 and resolver 25 may be completely accommodated in the hollow portion 18b of the driving rotor portion 17.
Alternatively, the arrangement of the bearings 30 and 40 and the resolver 25 in the axial direction may be reversed, and a part or all of the resolver 25 may be accommodated in the hollow portion 18 b of the driving rotor unit 17. In this case, a part or all of the bearings 30 and 40 may be accommodated in the hollow portion 18b of the driving rotor unit 17.
[0045]
In the above embodiment, the opening 20h of the housing / holding portion 20b of the lid member 20 is closed by the resolver connector 37. However, the opening 20h may be closed by other than the connector 37. Further, the shape of the resolver connector 37 is not limited to this, and for example, the opening 37a of the connector 37 may be oriented in a direction other than the axial direction.
[0046]
In the above embodiment, the driving stator 3 and the power supply connector 9 are connected by using the wiring member 6 in which the wiring board 8 is inserted into the insulating portion 7, but the configuration of the wiring member 6 is not limited to this. Not something. Alternatively, the connection may be made using a lead wire without using such a wiring member 6.
[0047]
In the above embodiment, the annular disc spring 36 is used as the biasing member, but the present invention is not limited to this. For example, a coil spring or a wave washer may be used.
[0048]
In the above embodiment, the resolver 25 as shown in FIG. 1 is used as the rotation sensor, but the configuration of the resolver may be appropriately changed. Further, a rotation sensor having a rotor and a stator other than the resolver may be used. For example, a rotation sensor using an optical detection element or a magnetic detection element may be used.
[0049]
In the above embodiment, the rotor core portion 18 is formed integrally with the rotation shaft 16 in the driving rotor portion 17, but the rotor core portion 18 may be assembled separately from the rotation shaft 16.
[0050]
The configuration of the brushless motor 1 of the above embodiment may be appropriately changed other than the above. For example, although the substantially cylindrical motor case 2 with a bottom is used, a substantially cylindrical motor case having both ends opened in the axial direction may be used. Further, the lid member 20 may be formed of a material other than metal.
[0051]
【The invention's effect】
As described in detail above, according to the present invention, it is possible to provide a brushless motor that can be downsized in the axial direction.
[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 a conventional brushless motor.
[Explanation of symbols]
2 ... motor case, 2b ... opening, 3 ... drive stator, 6 ... wiring member, 7 ... insulating part, 8 ... wiring board, 15 ... rotor, 17 ... drive rotor part, 18a ... opening, 18b ... hollow Reference numeral 20: lid member, 20b: housing and holding unit, 25: resolver as a rotation sensor, 26: resolver stator as a sensor stator, 27: resolver rotor unit as a sensor rotor unit, 30: bearing Metal bearings, 36: Belleville springs as urging members, 37: resolver connectors as sensor connectors, 37a: openings, 40: ball bearings as bearings.

Claims (7)

A brushless motor provided with a rotation sensor for supplying a drive voltage to the drive stator to rotate a rotor disposed inside the drive stator and detecting a rotational position of the rotor to generate the drive voltage And
The rotor is provided with a driving rotor unit corresponding to the driving stator and a sensor rotor unit constituting the rotation sensor,
A sensor stator corresponding to the sensor rotor portion and a bearing rotatably supporting the rotor are held by a housing holding portion recessed in a lid member for closing an opening of a motor case,
A hollow portion having an opening in the axial direction is formed in the driving rotor portion, and the holding portion of the lid member is housed in the hollow portion so as to house at least one of the bearing and the rotation sensor. A brushless motor characterized in that a part is inserted. The brushless motor according to claim 1,
A brush connector, wherein a sensor connector for outputting a detection signal from the rotation sensor is provided at an opening of the holding portion of the lid member so as to close the opening of the holding portion. motor. The brushless motor according to claim 2,
The brushless motor according to claim 1, wherein the sensor connector is configured so that an opening thereof is directed outward in the axial direction such that a connection direction with the external connector is substantially axial. The brushless motor according to any one of claims 1 to 3,
A wiring member obtained by inserting a wiring board into an insulating portion to supply the driving voltage to the driving stator is disposed on the lid member side of the stator.
The brushless motor according to claim 1, wherein the wiring member is formed in an annular shape so as to be positioned radially outward of the holding portion of the lid member. The brushless motor according to claim 4,
An urging member for pressing and fixing the wiring member and the driving stator to the motor case is provided between the wiring member and the lid member, and the urging member is A brushless motor, wherein the brushless motor is formed in an annular shape so as to be located radially outside of the holding portion of the lid member. The brushless motor according to any one of claims 1 to 5,
The said cover member is formed with the metal plate, The brushless motor characterized by the above-mentioned. The brushless motor according to any one of claims 1 to 6,
The brushless motor according to claim 1, wherein the rotation sensor is a resolver.

Images