JP2007053852A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the attachment of parts in the direction of a rotating shaft simply and accurately, regardless of the dimensional accuracy in the rotating shaft direction of a stator core. <P>SOLUTION: In upper and lower core covers 31 and 32, the ends of the small-diameter parts 43a and 43b of tubular parts 41a and 42b are provided with engaging parts 40 which engage with each other when the small diameter parts 43a and 43b are inserted into the through hole 6a of the stator core 6, thus the connection and the integration of the core covers 31 and 32 are enabled, whereby the positioning in the rotating shaft direction of bearings 14a and 14b retained in upper and lower bearing holders 33 and 34 made integrally in the core covers 31 and 32 can be performed easily and surely. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brushless motor, and more particularly, to a motor that simplifies an assembling operation and improves a finished dimensional accuracy at the completion of assembling.

Conventionally, as this type of brushless motor, for example, a motor having a configuration as disclosed in Patent Document 1 or the like is known.
That is, the brushless motor disclosed in Patent Document 1 has a rotor in which permanent magnets are arranged in an annular shape, and the rotor is fixed to the rotating shaft, while having an outer peripheral surface facing the permanent magnet of the rotor, It has a stator around which an exciting coil is wound. A through hole is formed in the center of the stator core that constitutes the stator, and bearing holders are attached to both ends of the through hole. The bearing holder is fixed with a bearing that rotatably holds the rotating shaft, and the rotating shaft is provided so that the vicinity of both ends thereof is held by the bearing and the through hole can be inserted. Yes.
Further, a core cover made of an insulating member material is attached to the upper and lower surfaces of the stator core in order to wind the exciting coil.

JP-A-9-84318 (page 2-4, FIG. 1)

  However, in the above-described conventional brushless motor, each of the two bearing holders and the core cover is attached to the upper and lower surfaces of the stator core, and is maintained separately from each other after the attachment. Depending on the thickness of the stator core, that is, the dimensional accuracy of the length in the direction of the rotation axis, the position of the two bearings in the direction of the rotation axis, the position of the sensor magnet attached to one end of the rotation axis, etc. It was not possible to define it unambiguously, and it was necessary to check each installation position each time, so that the assembly work was complicated. It was.

That is, the stator core is generally configured by laminating a plurality of thin silicon steel plates, for example, but since the finished dimensional tolerance of one silicon steel plate is relatively large, the thickness of the stator core along the rotation axis direction is relatively small. The dimensional accuracy must be relatively low, but it is the current situation.
Therefore, the distance in the rotation axis direction of the bearing holders respectively attached to the upper and lower surfaces of the stator core changes depending on the thickness in the rotation axis direction of the stator core, and the magnitude of the change is that of the silicon steel plate as described above. Due to the roughness of the dimensional accuracy, the originally required dimensional accuracy may not be satisfied. For this reason, the actual distance between the two bearing holders is measured each time the assembly work is performed, and a sensor magnet attached to the rotating shaft based on the position of the bearings fixed to these bearing holders according to the measurement results. The mounting position of the other components must be determined, and the work efficiency is extremely poor, which has been an obstacle to reducing the cost of the apparatus.

  Further, in the conventional brushless motor, since the bearing holder and the core cover are both formed separately from each other and are respectively attached to the upper and lower surfaces of the stator, There is a problem that it is not possible to meet the demands for reducing the number of parts and simplifying the configuration of the entire brushless motor.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to easily perform the mounting operation of a part such as a bearing that requires mounting at a predetermined position in the rotation axis direction regardless of the finished dimensional accuracy of the stator core. The present invention provides a brushless motor that can be reliably performed at a predetermined position.
Another object of the present invention is to provide a brushless motor that can maintain a high distance accuracy between bearings.
Another object of the present invention is to provide a brushless motor capable of reducing the number of parts and simplifying the configuration as compared with the conventional art.

In order to achieve the above object of the present invention, a brushless motor according to the present invention comprises:
There is provided a stator in which an exciting coil is wound around a stator core, and a permanent magnet is disposed on a rotating shaft that is rotatably supported so as to face the outer peripheral surface of the stator. A brushless motor to which the rotor is fixed,
Two core covers are provided which are fitted in each other in the axial direction of the rotary shaft and form a stator core storage space for storing the stator so as to sandwich the stator from above and below.

According to the present invention, since the two core covers are connected and integrated in the direction of the rotation axis by fitting, the length of the integrated core cover in the direction of the rotation axis differs from the conventional case where the two core covers are separated. The dimensional accuracy of the core cover is easily maintained, and the distance between the two bearing holders provided together with the core cover in the direction of the rotational axis is unambiguous. The cost of the apparatus can be reduced by simplifying the assembly work.
In particular, when the core cover and bearing holder are integrated, the distance accuracy between the bearings in the direction of the rotation axis can be kept high by simple assembly work, and the number of components is reduced and the configuration is simplified. Can be achieved.
Further, by setting the size of the stator core storage space in the rotation axis direction, in particular, the minimum dimension value thereof within a range in which the stator core can be securely stored even if there is a dimensional error in the thickness of the stator core in the rotation axis direction. Unlike assembly, there is no need to reset the mounting position of other components in the direction of the rotation axis in accordance with the error in the thickness of the stator core, and the work can be greatly simplified. .

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, the overall configuration of the brushless motor in the embodiment of the present invention will be described with reference to FIG. 1. The brushless motor in the embodiment of the present invention includes a stator 2 having a base fixed to a casing 1, The rotor 3 is rotatably divided into the stator 2 and a circuit board 4 on which an electronic circuit for controlling energization of the exciting coil 7 wound around the stator 2 is mounted.

The stator 2 according to the embodiment of the present invention includes a stator core 6, upper and lower core covers 31 and 32 that are mounted so as to sandwich the stator core 6 from above and below, and the stator core 6 via the upper and lower core covers 31 and 32. The exciting coil 7 is wound around the rotor 3.
The stator core 6 in the embodiment of the present invention has a so-called laminated core structure in which magnetic members such as silicon steel plates formed in a thin plate shape are laminated in multiple stages. The stator core 6 has a through hole 6a into which the upper and lower core covers 31 and 32 are press-fitted in the central portion thereof, and a plurality of coil winding portions 8 are radially formed from the peripheral wall 6b that defines the through hole 6a. Further, it has a known configuration having a magnetic pole surface 9 which is formed in an arc shape so as to correspond to the rotating circle of the permanent magnet 13 of the rotor 3 connected to the coil winding portion 8. It has become.

  The upper and lower core covers 31 and 32 in the embodiment of the present invention are made of an insulating member such as a synthetic resin, and will be described in detail later. The upper and lower bearing holders 33 and 34 are integrated, respectively. The upper and lower bearings 14a and 14b are held by the bearing holders 33 and 34, and the rotary shaft 12 is rotatably supported by the upper and lower bearings 14a and 14b.

  The rotor 3 has a yoke 11 formed in a general shape, with an open surface on the casing 1 side and a closed surface forming an upper surface, and a rotating shaft 12 at the center of the closed surface. A shaft through hole 11a through which is penetrated is formed. That is, the rotor 3 is press-fitted and fixed to the rotary shaft 12 through the shaft through hole 11a, is supported in the axial direction by the thrust stopper 15, and is held on the casing 1.

A plurality of permanent magnets 13 are fixed to the inner peripheral surface of the yoke 11 at an appropriate interval in the circumferential direction, and are opposed to the outer peripheral surface of the stator core 6 at an appropriate interval. .
Further, for example, a sirocco fan 5 is fixed to the rotary shaft 12 at an upper end portion 12 a protruding from the upper portion of the rotor 3.

The casing 1 includes a motor holder 21 and a substrate cover 22, and a storage space 23 is formed between the two and the circuit board 4 is stored therein. In the embodiment of the present invention, the substrate cover 22 is screwed on the back surface side of the motor holder 21, that is, on the side opposite to the surface (front surface) on which the rotor 3 and the stator 2 are located. It has become.
The circuit board 4 is screwed to a support column (not shown) that protrudes from the lower surface side (back surface side) of the motor holder 21 and is held and accommodated in the casing 1. The circuit board 4 is mounted with a known energization drive circuit that controls energization to the excitation coil 7 based on a control signal input from the outside.

Further, one end of the rotating shaft 12 faces the casing 1, and a sensor magnet 26 is fixed in the vicinity of the end.
The circuit board 4 is provided with a hall element (not shown) at an appropriate position facing the sensor magnet 26, and a detection signal corresponding to the rotational position of the rotor 3 is generated by an excitation coil by the circuit board 4. 7 is used for energization control to the power source 7.

Next, the upper and lower core covers 31 and 32 in the embodiment of the present invention will be described in detail with reference to FIG. 1 and FIG.
The upper core cover 31 and the lower core cover 32 in the embodiment of the present invention basically have the same configuration except for a fitting portion described later. Therefore, hereinafter, the upper core cover 31 will be described, and in this case, the reference numerals of the corresponding constituent elements of the lower core cover 32 will be written in parentheses after the reference numerals of the constituent elements constituting the upper core cover 31, The description of the structure of the upper core cover 31 will be replaced with the description of the structure of the lower core cover 32.

The upper core cover 31 has a cylindrical portion 41a (41b) whose external shape is formed in a substantially hollow cylindrical shape, and a plurality of coil windings of the stator core 6 are provided on the outer peripheral surface of the cylindrical portion 41a (41b). A plurality of flange portions 42a (42b) corresponding to the portion 8 are integrally formed to protrude outward along the radial direction of the tubular portion 41a (41b) (see FIG. 1).
The cylindrical portion 41a (41b) includes a small-diameter portion 43a (43b) and a large-diameter portion 44a (44b). The small-diameter portion 43a (43b) has an outer diameter that can be press-fitted into the through hole 6a of the stator core 6. It is substantially coincident with the inner diameter of the hole 6a. The flange portion 42a (42b) is integrally formed so as to protrude outward corresponding to the coil winding portion 8 of the stator core 6 at a portion moving from the small diameter portion 43a (43b) to the large diameter portion 44a (44b). .

Further, in the inside of the small diameter portion 43a (43b), that is, in a portion formed in a hollow cylindrical shape, gradually from the end on the large diameter portion 44a (44b) side in the opposite direction to the large diameter portion 44a (44b). A bearing support piece 46a (46b) having a shaft hole 45 through which the rotary shaft 12 can pass is extended at the center thereof.
The bearing support piece 46a and the previous large-diameter portion 44a constitute the upper bearing holder 33. Similarly, the bearing support piece 46b and the large-diameter portion 44b constitute the lower bearing holder 34, and The upper bearing holder 33 is integrated with the upper core cover 31, and the lower bearing holder 34 is integrated with the lower core cover 32 (see FIG. 1).

A fitting step portion 47 is formed in an annular shape on the outer peripheral surface of the end portion of the upper core cover 31 opposite to the large diameter portion 44a (see FIG. 2A). That is, the fitting step portion 47 has a stepped annular peripheral wall 48 formed by cutting out the outer peripheral surface of the end portion of the small diameter portion 43a of the upper core cover 31 (see FIG. 2A). ).
On the other hand, the thickness of the small diameter portion 43 b of the lower core cover 32 is set to be thinner than the thickness of the small diameter portion 43 a of the upper core cover 31. The wall thickness L1 of the small diameter portion 43b of the lower core cover 32 is preferably set to be approximately equal to the radial width L2 of the fitting step portion 47 (see FIG. 2A).

  Thus, in this embodiment, the fitting step 47 of the upper core cover 31 described above and the small diameter of the lower core cover 32 having a thickness substantially equal to the interval L2 in the radial direction of the fitting step 47. The fitting part 40 is comprised by the edge part of the part 43b (refer FIG. 2 (A)).

In such a configuration, the upper core cover 31 and the lower core cover 32 are connected and integrated in the axial direction of the rotary shaft 12 as described below.
That is, first, the upper core cover 31 and the lower core cover 32 are press-fitted into the through holes 6a of the stator core 6 from the end portions of the small diameter portions 43a and 43b so as to sandwich the stator core 6 from above and below. The end of the small-diameter portion 43b of the lower core cover 32 and the small-diameter portion 43a of the upper core cover 31 are located in the vicinity where the distal end portions of the small-diameter portions 43a and 43b are located approximately near the center in the axial direction of the through hole 6a. It enters the fitting step 47 formed in the vicinity of the tip. And when the front-end | tip part of the small diameter part 43b of the lower core cover 32 contact | abutted to the bottom part 47a of the fitting step part 47, while fitting of the small diameter parts 43a and 43b is completed, press-fit is completed, thereby The core covers 31 and 32 are connected and integrated in the axial direction of the rotary shaft 12 (see FIG. 2A).

  In this state where the upper and lower core covers 31 and 32 are connected and integrated by fitting the small diameter portions 43a and 43b, between the flange portion 42a of the upper core cover 31 and the flange portion 42b of the lower core cover 32, A core storage space 49 is defined by the flange portions 42a and 42b and a part of the outer peripheral surface of the small diameter portions 43a and 43b, and the stator core 6 is positioned (see FIG. 2A).

  Here, in the embodiment of the present invention, the upper and lower core covers 31 and 32 are connected and integrated as described above, and the exciting coil 7 is not wound around the flange portions 42a and 42b. In the state, an interval in the core storage space 49 between the flange portion 42a of the upper core cover 31 and the flange portion 42b of the lower core cover 32, in other words, the length L3 of the core storage space 49 in the axial direction of the rotary shaft 12 is It is set to be equal to or slightly larger than the thickness L4 of the stator core 6 in the axial direction of the rotating shaft 12 (see FIG. 2A).

More specifically, first, the length L3 of the core housing space 49 and the thickness L4 of the stator core 6 are assumed to be design values, respectively, while the minimum dimension tolerance of L3 is −α and the maximum dimension tolerance of L4 is Assume + β respectively.
The distance between the flange portion 2a of the upper core cover 31 and the flange portion 42b of the lower core cover 32 in the core storage space 49, in other words, the length of the core storage space 49 in the axial direction of the rotary shaft 12 is the rotational axis. It is preferable that the thickness of the stator core 6 in the 12 axial directions is set to a size that satisfies L3-α ≧ L4 + β.

  In other words, if the value obtained by subtracting the minimum dimensional tolerance from the design value is defined as the minimum dimensional value, and the value obtained by adding the maximum dimensional tolerance to the design value is defined as the maximum dimensional value, the core storage space in the axial direction of the rotary shaft 12 is defined. It is preferable that the minimum dimension value of the length 49 is set to be equal to or greater than the maximum dimension value of the thickness of the stator core 6 in the axial direction of the rotating shaft 12.

  Actually, the minimum dimension value of the core housing space 49 in the axial direction of the rotating shaft 12 is about 0 to +2 mm with respect to the maximum dimension value of the thickness of the stator core 6 in the axial direction of the rotating shaft 12. Is preferred. This is because if the difference is larger than this, the upper and lower core covers 31 and 32 may not be adapted to the stator core 6 when the exciting coil 7 is wound around the upper and lower core covers 31 and 32.

As a result of setting the length of the core storage space 49 in the axial direction of the rotary shaft 12 as described above, the flange portions 42a and 42b of the upper and lower core covers 31 and 32 integrated by fitting in the small diameter portions 43a and 43b. Depending on the actual finished state of the upper and lower core covers 31, 32 and the stator core 6, there may be a slight gap (see FIG. 2A).
However, the upper and lower core covers 31 and 32 are formed of a resin member that can be sufficiently bent, so that the flanges 42a and 42b are sufficiently in close contact with the stator core 6 even when the exciting coil 7 is wound around the flanges 42a and 42b. (See FIG. 2B).

  In the embodiment of the present invention, the upper and lower core covers 31 and 32 are connected and integrated with each other by fitting in the small diameter portions 43a and 43b as described above. The lengths of the upper and lower core covers 31 and 32 are uniquely determined, and are not determined according to the finished accuracy of the thickness of the stator core 6 in the axial direction of the rotating shaft 12 as in the prior art. The element is surely excluded.

  As the lengths of the upper and lower core covers 31 and 32 in the axial direction of the rotary shaft 12 are uniquely determined, the positions of the upper and lower bearings 14a and 14b are uniquely determined. Such positioning can also be performed mechanically.

Thus, the upper and lower bearing holders 33 and 34 integrated with the upper and lower core covers 31 and 32 are provided with upper and lower bearings 14a and 14b as described below.
The upper bearing 14a is fixed to the bearing support piece 46a of the upper bearing holder 33, and the lower bearing 14b is fixed to the bearing support piece 46b of the lower bearing holder 34 as described below. A part is located in each large diameter part 44a, 44b (refer FIG. 1).

  That is, the thrust stopper 15 is positioned on the rotary shaft 12 in the vicinity of the end surface of the upper bearing 14a opposite to the side in contact with the bearing support piece 46a, and the detailed description is provided between the thrust stopper 15 and the upper bearing 14a. Although not shown, a plurality of upper washers 51a are arranged so that the sliding resistance between the thrust stopper 15 and the upper bearing 14a is reduced. Here, the upper washer group 51a is preferably composed of, for example, at least one nylon-based washer, a washer made of NBR rubber, and POM (polyacetal).

  The upper bearing 14a is annularly brought into contact with the outer peripheral surface of the upper bearing 14a on the thrust stopper 15 side, and the upper bearing stopper 52a is press-fitted into the large diameter portion 44a so as to come into contact with the inner peripheral surface of the large diameter portion 44a. The bearing support piece 46a is fixed. A felt 53 containing lubricating oil is disposed between the upper bearing stopper 52a and the end of the small diameter portion 43a on the large diameter portion 44a side, and lubricates the upper bearing 14a formed of sintered metal. Oil can be supplied.

  On the other hand, the end surface of the sensor magnet 26 fixed to the rotating shaft 12 is positioned in the vicinity of the end surface of the lower bearing 14b opposite to the side in contact with the bearing support piece 46b. In addition, a plurality of detailed illustrations are omitted between the two, but a plurality of lower washers 51b are arranged so that the sliding resistance between the sensor magnet 26 and the lower bearing 14b is reduced. It is. A suitable configuration example of the lower washer group 51b is the same as that of the upper washer group 51a.

  Then, the lower bearing 14b is annularly contacted with the outer peripheral surface of the lower bearing 14b on the sensor magnet 26 side, and the lower bearing stopper 52b press-fitted into the large diameter portion 44b so as to contact the inner peripheral surface of the large diameter portion 44b. The bearing support piece 46b is fixed. A felt 53 containing lubricating oil is disposed between the lower bearing stopper 46b and the end of the small diameter portion 43b so that the lubricating oil can be supplied to the lower bearing 14b formed of sintered metal. It has become.

In the above-described configuration example, the fitting portion 40 is configured such that the stepped annular peripheral wall 4 formed in the small diameter portion 43 a of the upper core cover 31 fits inside the small diameter portion 43 b of the lower core cover 32. However, it is needless to say that the present invention is not necessarily limited to such a configuration.
For example, contrary to the above-described configuration example, the fitting step portion 47 is provided in the small diameter portion 43 b of the lower core cover 32, and the thickness in the radial direction of the small diameter portion 43 a of the upper core cover 31 is set to the diameter of the fitting step portion 47. A configuration may be adopted in which the width L2 in the direction is set approximately equal.

Moreover, the form of fitting does not need to be limited to the above-described configuration example, and other fitting forms may be used.
That is, for example, as shown in FIG. 3, as in the above configuration example, the fitting step portion 47 </ b> A is formed on the outer peripheral surface of the end portion of the small diameter portion 43 a of the upper core cover 31, while the small diameter portion of the lower core cover 32 is formed. It is good also as a structure which formed the fitting step part 47B in the edge part inner peripheral surface of 43b. In such a configuration, the stepped annular peripheral wall 48a of the small diameter portion 43a of the upper core cover 31 is the fitting stepped portion 47B of the lower core cover 32, and the stepped annular peripheral wall 48b of the small diameter portion 43b of the lower core cover 32 is the upper core cover. The upper and lower core covers 31 and 32 are connected and integrated into the fitting step portion 47A of 31.

In the above configuration example, the upper and lower bearing holders 33 and 34 are integrated with the upper and lower core covers 31 and 32, but only one of the upper and lower bearing holders 33 and 34 is attached to the core covers 31 and 32. The structure integrated may be sufficient.
Furthermore, the upper and lower bearings 14a and 14b in the embodiment of the present invention are oil-impregnated bearings, but need not be limited to this, and may be other types of bearings such as ball bearings. May be.

It is a longitudinal cross-sectional view which shows the structural example of the brushless motor in embodiment of this invention. FIG. 2 is an enlarged cross-sectional view of a fitting portion of upper and lower core covers of the brushless motor shown in FIG. 1, and FIG. 2 (A) is an enlarged cross-sectional view showing a fitting portion before winding an exciting coil, FIG. ) Is an enlarged cross-sectional view showing a fitting portion in a state where an exciting coil is wound. It is sectional drawing which shows the other Example of the fitting part of an upper and lower core cover.

Explanation of symbols

31 ... Upper core cover 32 ... Lower core cover 33 ... Upper bearing holder 34 ... Lower bearing holder 40 ... Fitting portions 41a, 41b ... Cylindrical portions 42a, 42b ... Ling portions 46a, 46b ... Bearing support piece 49 ... Core storage space

Claims (6)

There is provided a stator in which an exciting coil is wound around a stator core, and a permanent magnet is disposed on a rotating shaft that is rotatably supported so as to face the outer peripheral surface of the stator. A brushless motor to which the rotor is fixed,
A brushless motor comprising two core covers that are fitted in each other in the axial direction of the rotary shaft and that form a stator core storage space for storing the stator core so as to sandwich the stator core from above and below. .   The core cover is provided with a cylindrical portion formed in a substantially hollow cylindrical shape, and a plurality of flanges formed to protrude in the radial direction at appropriate intervals in the circumferential direction on the outer peripheral surface of the cylindrical portion. The fitting portion is formed at one end portion of the cylindrical portion together with one end portion of the other cylindrical portion to be paired. Brushless motor.   3. The brushless according to claim 2, wherein a bearing holder for holding a bearing for rotatably supporting the rotating shaft is integrally formed at a portion in the vicinity of the protruding portion of the flange portion of the cylindrical portion. motor.   The bearing holder includes a bearing support piece that is formed to protrude from the inner wall of the hollow portion of the cylindrical portion so that the bearing can be attached, and in which a shaft hole through which the rotation shaft can penetrate is formed. The brushless motor according to claim 3.   The minimum dimension value of the length along the rotation axis direction of the core housing space formed by fitting the two core covers is set to be equal to or larger than the maximum dimension value of the length in the rotation axis direction of the stator core. The brushless motor according to claim 4.   The minimum dimension value of the length along the rotation axis direction of the core storage space is a range of 0 or more and not exceeding +2 mm with respect to the maximum dimension value of the length of the stator core in the rotation axis direction. The brushless motor described.

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