JP4001885B2 - Brushless motor - Google Patents

Description

  The present invention relates to a brushless motor used as a main motor for simultaneously driving various mechanisms such as a copying machine and a laser beam printer.

  In recent years, document products such as copiers and laser beam printers have been aimed at higher image quality, higher speed printing, and colorization in recent years, and in order to realize them simultaneously, so-called tandem systems are provided with a photosensitive drum for each color. There is a tendency. Although the conventional one-drum configuration is a two-drum and four-drum configuration, the size of the equipment cannot be denied, but the main motor that drives various mechanisms to reduce the size is reduced in thickness. There is a demand for smaller diameter, space saving, and higher output.

  And as a main motor, a brushless motor that incorporates a motor unit having a stator with a stator core (iron core) suitable for high output and a drive / control circuit for rotationally driving and controlling the motor is generally used. Therefore, it is required to reduce the thickness, diameter, space, and output of the entire motor including the circuit portion.

  For this purpose, the outer diameter of the rotor part of the motor is reduced, the outer dimension of the circuit part is close to the square dimension circumscribing the rotor part, and the height dimension is similarly close to the height dimension of the rotor part. It is desirable to do.

  Conventionally, a brushless motor in which a circuit unit is integrated with a motor includes a stator in which a coil is wound around a stator core, and a ring-shaped magnet having a plurality of magnetic poles facing the stator core on the inner peripheral surface of a cup-shaped rotor frame. It is generally configured to include a rotor that is fixed and has a shaft attached to the center, a bearing that supports the shaft of the rotor, and a housing that holds the bearing, and a stator core and a circuit board on which circuit components are mounted are attached to the housing. (For example, see Patent Document 1).

FIG. 11 shows the structure of the first conventional example.
Reference numeral 18 denotes a rotor frame (cup part), and 20 a rotor magnet (driving magnet), which is fixed to the rotor frame 18 together with a speed detection magnet 22. It is configured. The shaft 24 is rotatably supported by bearings 28 and 28 held by the housing 12.

  A stator core 48 and a circuit board 30 disposed to face the rotor magnet 20 are attached to the housing 12, and a control integrated circuit 34 for rotating and controlling the rotor 16 on the circuit board 30. A drive / control circuit having the above is mounted.

  However, in this conventional configuration, a space for inserting the bolts 46 that fix the stator core 48 and the circuit board 30 to the housing 12 is required in the inner peripheral portion of the stator core 48. Furthermore, a space for fitting the outer peripheral portion of the housing 12 holding the bearings 28 on the inner periphery into a hole formed in the center of the stator core 48 is also required.

  In order to reduce the outer diameter of the rotor 16, it is necessary to reduce the outer diameter of the stator core 48. Therefore, there is a problem that the space for winding the coil 14 around the stator core 48 is reduced and the output of the motor is significantly reduced.

  In addition, as shown in FIG. 11 and FIG. This is because the base end portion of the housing 2 is fixed to the plate 1, the circuit board 30 on which the drive / control circuit is mounted is screwed to the housing 2 with bolts 31, and the stator core 33 provided with the winding 32 is bolted 34 is fixed to the housing 2 as shown in FIG. In this case, there is a problem similar to that of the first conventional example.

In order to solve this problem, there is Patent Document 2 shown in FIGS. 14 and 15.
In the second conventional example, in the fitting portion between the housing 2 that holds the bearings 11 and 12 that support the shaft 6, the stator core 3 that is provided with the winding 5, and the plate 1, Convex portions 2 a are formed in the inner peripheral portion of the stator core 3, and concave portions 3 a are formed. After engaging the convex part 2a of the housing 2 and the concave part 3a of the stator core 3, it is fixed by caulking.

As described above, according to the second conventional example, the space of the fastening portion between the stator core 3 and the housing 2 can be made smaller than in the first conventional example, so that a space for winding more coils in the stator core 3 can be secured. An efficient motor is obtained.
Japanese Utility Model Publication No. 7-9067 (FIG. 1) Japanese Patent Laid-Open No. 11-89196 (2nd page, FIG. 2)

However, even in the second conventional example, the problem that the inner peripheral portion of the stator core 3 requires a space for fitting the housing 2 is not solved.
The present invention solves such a conventional problem, and an object of the present invention is to provide a brushless motor that is thin, small in diameter, space-saving, and high in output.

  The brushless motor according to claim 1 of the present invention has a plurality of salient poles and a stator core wound around the salient poles, and is arranged to face the stator core and performs a plurality of drive magnetizations in the circumferential direction. A rotor composed of a cup-shaped rotor frame with the ring-shaped magnet attached to the inner periphery thereof, a shaft fixed to the center of the rotor frame, two bearings for rotatably supporting the shaft, and the bearings and A housing for holding the stator core, and of the two bearings, a part of the outer periphery of the bearing disposed near the stator core directly contacts the inner periphery of the hole formed in the center of the stator core. And at least another part of the outer periphery of the bearing is held on the inner periphery of a cylindrical portion formed in the center of the housing, A plurality of protrusions are formed toward the direction stator core side, and the stator core is formed with a plurality of first notches into which the protrusions can be inserted at positions corresponding to the protrusions, and the first notches The portion is formed such that the radial depth dimension is shallower on the side of the end surface on the stator core side of the housing than the opposite side, and plastic deformation is performed in the radial depth direction at a location where the radial depth dimension is shallow inside the plurality of first cutout portions. A second notch is formed at a position where the protrusion is engaged.

  A brushless motor according to a second aspect of the present invention is the brushless motor according to the first aspect, wherein the stator core is formed by stacking two types of cores having different radial depth dimensions of the first notch.

  The brushless motor according to a third aspect of the present invention is the brushless motor according to the second aspect, wherein the second notch is formed in a range radially inward from the radial outer periphery of the other core having a large depth dimension. .

  A brushless motor according to a fourth aspect of the present invention is the brushless motor according to any one of the first to third aspects, wherein the plurality of cutout portions correspond to salient poles on the outer periphery of the stator core at the inner periphery of the hole formed in the center of the stator core. It is characterized in that it is formed along the circumferential direction at the position to be.

  A brushless motor according to a fifth aspect of the present invention is the brushless motor according to the first aspect, wherein the outer periphery of the bearing disposed at a position close to the stator core is in contact with the housing only at the position of the protrusion within the thickness range of the stator core. It is characterized by that.

  According to the configuration of claim 1 of the present invention, a part of the outer periphery of the bearing disposed at a position close to the stator core directly contacts the inner periphery of the hole formed in the center of the stator core, A part of the outer periphery of the bearing arranged at a position close to the stator core is held by the inner periphery of a cylindrical portion formed in the center of the housing, and a plurality of protrusions from the end surface on the stator core side of the housing toward the axial stator core side And the stator core has a plurality of first cutout portions through which the protrusions can be inserted at positions corresponding to the protrusions, so that the housing is formed between the hole formed in the center of the stator core and the bearing. Therefore, the diameter of the hole can be reduced. In addition, by inserting a plurality of protrusions formed on the cylindrical portion of the housing into the notch formed on the stator core and then crimping the protrusions, the stator core can be mounted in a small space without using a fixing member such as a bolt. Become. Further, the first notch is formed such that the radial depth dimension is shallower on the end face side of the stator core side of the housing than the opposite side, and the radial depth dimension is shallow at the inside of the plurality of first notch parts. Since the second notch is formed at a position where the projection deformed plastically in the depth direction is engaged, it is possible to increase the strength of the stator core in the rotational direction and the axial direction. This configuration is particularly effective when the protrusion is made small to reduce the space for fixing.

  As a result, a space for winding the coil around the stator core can be secured, so that a reduction in output can be prevented, and a brushless motor suitable for reduction in diameter, space saving, and high output can be realized.

  According to the configuration of claim 2 of the present invention, the stator core is configured by stacking two types of cores having different radial depth dimensions of the first notch, so that a complicatedly shaped stator core can be easily obtained. realizable.

  According to the configuration of claim 3 of the present invention, the second notch is formed in a range radially inward from the radial outer periphery of the other core having a large depth dimension. However, since the contact area can be increased further to the back of the cross section of the second cutout portion, the strength in the rotational direction and the axial direction can be increased.

  According to the fourth aspect of the present invention, the notch is formed along the circumferential direction at a position corresponding to the salient pole on the outer periphery of the stator core on the inner periphery of the hole formed in the center of the stator core. The first notch can be moved away from the inner periphery of the stator core, which is the connecting part of the salient poles, and the influence of the increase in the magnetic resistance of the connecting part of the salient poles where the magnetic flux is concentrated can be suppressed. Since there is no need to shallow the outer side in the direction, a space for winding the winding around the stator core can be secured, and a brushless motor can be realized that can prevent a decrease in output, reduce the diameter, save space, and increase the output.

  According to the configuration of claim 5 of the present invention, the outer periphery of the bearing arranged at a position close to the stator core is in contact with the housing only at the position of the projection of the housing, so that the space of the inner peripheral portion of the stator core is effective. Since a space for winding the winding around the stator core can be secured, a reduction in output can be prevented, and a brushless motor suitable for reduction in diameter, space saving, and high output can be realized.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1 shows a brushless motor of the present invention.
The stator core 50 has a plurality of salient poles 50a, and windings 51 are wound around the salient poles 50a. The ring-shaped magnet 52 arranged to face the stator core 50 is subjected to a plurality of drive magnetizations in the circumferential direction. The ring-shaped magnet 52 is attached to the inner peripheral side of the cup-shaped rotor frame 53. A shaft 54 is attached to the center of the rotor frame 53, and the rotor 55 is configured by the ring-shaped magnet 52, the rotor frame 53, and the shaft 54.

  The shaft 54 is rotatably supported by two bearings 70a and 70b arranged with a space therebetween. The cylindrical housing 56 holds bearings 70a and 70b, a stator core 50, and a circuit board 57 on which a drive / control circuit for rotationally driving and controlling the rotor 55 is mounted. A mounting plate 58 is fixed to the end of the housing 56.

  The housing 56 of zinc alloy die casting is configured as shown in FIGS. 3 (a) is a view taken along the line AA 'in FIG. 3 (b), FIG. 3 (c) is a view taken along the line BB' in FIG. 3 (b), and FIG. It is a cross section along line CC ′.

  At one end of the housing 56, a first cylindrical portion 56a is formed at the center of the housing 56 so as to accommodate the bearing 70a. At the other end of the housing 56, a second cylindrical portion 56b is formed at the center of the housing 56 so as to accommodate the bearing 70b.

  An annular wall 60 for attaching a plate is formed on the inner peripheral portion of the first support surface 59 a at one end of the housing 56. The annular wall 60 has an outer peripheral surface formed vertically and an inner peripheral surface inclined in a direction from the distal end to the proximal end, and has a tapered shape and is continuous in a circumferential shape. On the second support surface 59b opposite to the first support surface 59a of the housing 56, first protrusions 61, 61, 61 for mounting a circuit board are formed. On the inner peripheral portion of the third support surface 59c at the other end of the housing 56, second protrusions 62a, 62b, 62c, 62d, 62e, and 62f for attaching the stator core are formed.

  The stator core 50 is configured as shown in FIGS. 4 and 5A, 5B, and 5C. 5 (a) is a view taken along the line AA 'of FIG. 5 (b), FIG. 5 (c) is a view taken along the line BB' of FIG. 5 (b), and FIG. It is a cross section along line CC ′.

  The stator core 50 formed by laminating magnetic steel plates has a hole 63 having a diameter that is the same as or slightly larger than the inner diameter of the second cylindrical portion 56b of the housing 56 at the center. The outer dimension of the second cylindrical portion 56b that accommodates the bearing 70b in the inner peripheral portion thereof is formed larger than the inner diameter dimension of the hole 63 of the stator core 50.

  A plurality of first notches 65 a to 65 f are formed on the inner peripheral surface of the hole 63 of the stator core 50 at positions corresponding to the second protrusions 62 a to 62 f of the housing 56. The stator core 50 formed by stacking is configured by stacking magnetic steel plates 66a and 66b as two types of cores having different cutting depths which are radial depth dimensions of the first cutout portions 65a to 65f. 5B, the cut depth J1 of several magnetic steel plates 66a on the AA ′ side is shallower than the cut depth J3 of the other magnetic steel plate 66b on the BB ′ side.

  In this embodiment, the thickness J2 of the second protrusions 62a to 62f is as thin as 0.5 mm to 0.7 mm, and the cutting depth J1 of the magnetic steel plate 66a is the same as that of the second protrusions 62a to 62f of the housing 56. It is formed to be equal to or slightly larger than the thickness J2.

  Further, a second notch 80 is formed in the magnetic steel plate 66a. Specifically, the second notches 80 extending in the axial direction are formed in a range radially inward from the outer circumference in the radial direction of the first notches 65a to 65f of the magnetic steel plate 66b.

  For assembly, the annular wall 60 of the housing 56 is inserted into the mounting hole 58a of the plate 58 shown in FIG. 2, and the annular wall 60 is crimped as shown in FIG. As a result, the plate 58 is sandwiched between the first support surface 59 a of the housing 56 and the crimped annular wall 60, and the housing 56 is attached to the plate 58.

  Next, the circuit board 57 is placed on the second support surface 59b of the housing 56 so that the hole 57a of the circuit board 57 is engaged with the outside of the second cylindrical portion 56b of the housing 56, and this first The protrusions 61, 61, 61 are crimped as shown in FIG. As a result, the circuit board 57 is held between the second support surface 59b of the housing 56 and the crimped first protrusions 61, 61, 61.

  Further, the stator core 50 provided with the winding 51 is positioned and placed so that the second protrusions 62 a to 62 f of the housing 56 are accommodated in the first notches 65 a to 65 f of the stator core 50. . At this time, the stator core 50 is set so that the side of the magnetic steel plate 66 a is the side of the third support surface 59 c of the housing 56. FIG. 6 shows the assembly process at this time. The winding 51 is not shown.

FIGS. 7A and 7B are an enlarged plan view and a longitudinal sectional view of the second protrusions 62a to 62f accommodated in the first notches 65a to 65f of the stator core 50 at this time.
In the next step, as shown in FIG. 7 (b), a punch 68 having a convex portion 67 having a narrower width than the first notches 65a to 65f corresponding to the first notches 65a to 65f of the stator core 50 is formed. Using, the second protrusions 62a to 62f are caulked to the imaginary line position. As a result, the plastic core-deformed second protrusions 62a to 62f and the first support surface 59c of the housing 56 hold the stator core 50 with sufficient strength.

  In the final process, after the bearings 70a and 70b are set on the first and second cylindrical portions 56a and 56b of the housing 56, the shaft 54 of the rotor 55 is set on the bearings 70a and 70b as shown in FIG. Is completed.

  As described above, the stator core 50 can be attached to the housing 56 without using the bolt as in the first conventional example. Further, of the two bearings 70 a and 70 b that support the rotor 55, a part of the outer periphery of the bearing 70 b disposed near the stator core 50 directly contacts the inner periphery of the hole 63 formed in the center of the stator core 50. Therefore, the diameter of the hole 63 formed in the center of the stator core 50 is larger than that in which the housing is interposed between the hole formed in the center of the stator core and the bearing as in the first and second conventional examples. Can be small. As a result, a space for winding the winding 51 around the stator core 50 can be secured, so that a reduction in output can be prevented, and a brushless motor suitable for a reduction in diameter, space saving, and high output can be realized. Furthermore, since the housing 56 can be made small, the material can be reduced, and a brushless motor can be provided at low cost.

  Furthermore, since the positions of the first notches 65a to 65f in the stator core 50 are appropriately set, the influence of an increase in magnetic resistance can be suppressed and a decrease in output can be prevented. Specifically, the positions of the first notches 65a to 65f are provided close to the base end of the salient pole 50a provided on the outer periphery of the stator core 50 as shown in FIG. Of the stator core inner periphery M, which is a connecting portion that connects the base ends of 50a, the first is located at a position away from the portion of the magnetic path that connects the adjacent salient poles 50a and concentrates the magnetic flux. Since the notches 65a to 65f are provided, the influence of an increase in the magnetic resistance can be suppressed, and at the same time, it is not necessary to shallow the slot portion of the stator core radially outward, so that a space for winding the stator core can be secured, so Decline can be prevented.

  Further, since the outer periphery of the bearing 70b contacts the housing 56 only at the positions of the second protrusions 62a to 62f within the range of the thickness of the stator core 50, the space of the inner periphery of the stator core 50 can be effectively utilized. Thus, a space for winding a coil around the stator core can be secured, and a decrease in output can be prevented.

  Furthermore, when the thickness J2 of the second protrusions 62a to 62f is as thin as 0.5 mm to 0.7 mm, the so-called “flat caulking” in which the tip of the protrusion is generally performed is a second protrusion 62a. ~ 62f was broken and the holding force required for fixing could not be obtained. Further, in the method of crushing from above the second protrusions 62a to 62f without bending the second protrusions 62a to 62f, the thickness of the second protrusions 62a to 62f is thin, so the cross section of the notch portion of the stator core The pressure-bonding force was insufficient, and the holding force required for fixing could not be obtained. When excessive pressure was applied from above the second protrusions 62a to 62f, buckling occurred up to the receiving portion of the housing 56 during caulking work. Therefore, in this embodiment, as described above, the second notch portion 80 is formed on the magnetic steel plate 66a located on the side of the third support surface 59c, which is the base end portion of the second protrusions 62a to 62f. Since the second protrusions 62a to 62f are plastically deformed by caulking, the second protrusions 62a to 62f are partially cut into the second notch 80 as indicated by phantom lines in FIG. The pressure at the time of caulking is concentrated on the second cutout 80, and at the same time, the area where the compressed second protrusions 62a to 62f are crimped to the axial cross section of the stator core 50 is increased. Necessary holding force can be obtained.

  Further, the second notch 80 is particularly effective in the case of this embodiment in which the housing 56 is formed by die casting. That is, when the housing 56 is formed by die casting, there is a large variation in the shape and dimensional accuracy of the second protrusions 62a to 62f, so the gap between the second protrusions 62a to 62f and the stator core 50 varies greatly. In other words, it is difficult to press the second protrusions 62a to 62f against the axial cross section of the stator core 50 with a pressing force that does not apply excessive pressure to the portion that receives the housing 56 during crimping. On the other hand, in this embodiment, since the second notch 80 is formed, the area to be crimped to the axial cross section of the stator core 50 is large, and the stator core 50 can be mounted even if the dimensional accuracy of the housing 56 varies. Since it can be securely fixed and it is not necessary to apply a large pressing force when crimping, it is possible to realize a good fixed state without causing buckling of the receiving portion of the housing 56.

  In the above embodiment, as shown in FIGS. 4, 5, and 7, one second notch 80 is formed in each of the first notches 65a to 65f. However, as shown in FIG. A plurality of second notches 80a and 80b may be formed in the magnetic steel plate 66a.

  In each of the above-described embodiments, the second cutout portions 80, 80a, 80b have a triangular cross-sectional shape. However, as shown in FIG. 9 and FIG. The same effect can be expected even with the notch 82.

  The brushless motor of the present invention is useful as a main motor for simultaneously driving various mechanisms such as a copying machine and a laser beam printer.

Sectional drawing of the brushless motor by embodiment of this invention The exploded perspective view of the principal part in the embodiment Bottom view, sectional view, top view of housing in the same embodiment The perspective view of the stator core in the same embodiment Bottom view, cross-sectional view, top view of stator core in the same embodiment The perspective view in the middle of the assembly in the same embodiment Main part enlarged plan view and sectional view of caulking process in the same embodiment Main part enlarged plan view of another embodiment Bottom view, sectional view, top view of stator core of another embodiment Bottom view, sectional view, top view of stator core of another embodiment Sectional view of the first conventional example Another exploded perspective view of bolting the stator core to the housing FIG. 12 is a perspective view in the middle of assembly. Sectional view of the second conventional example The exploded perspective view of the principal part of the conventional example

Explanation of symbols

50 Stator core 50a Stator core salient pole 51 Winding 52 Ring-shaped magnet 53 Rotor frame 54 Shaft 55 Rotor 56 Housing 56a First cylindrical portion 56b Second cylindrical portion 57 Circuit board 58 Plate 59a First support surface 59b Second Support surface 59c Third support surface (end surface on the stator core side of the housing)
60 annular wall 61 1st protrusion part 62a-62f 2nd protrusion part 63 Hole 65a-65f formed in the center of a stator core 1st notch part 66a, 66b Magnetic steel plate (core)
70a, 70b Bearing 80 Second notch J1 Cut depth J2 of magnetic steel plate 66a J2 Thickness of second protrusions 62a to 62f J3 Cut depth of magnetic steel plate 66b

Claims (5)

A stator core having a plurality of salient poles and wound around the salient poles;
A cup-shaped rotor frame, which is arranged opposite to the stator core and has a plurality of circumferentially magnetized ring magnets attached to the inner periphery, and a shaft fixed to the center of the rotor frame. And the rotor
Two bearings for rotatably supporting the shaft;
The bearing and the housing for holding the stator core, and of the two bearings, a part of the outer periphery of the bearing arranged at a position close to the stator core is in the inner periphery of the hole formed in the center of the stator core. Abut directly,
At least another part of the outer periphery of the bearing is held on the inner periphery of a cylindrical portion formed in the center of the housing,
A plurality of protrusions are formed from the end surface on the stator core side of the housing toward the axial stator core side,
The stator core has a plurality of first cutout portions into which the protrusions can be inserted at positions corresponding to the protrusions, and the first cutout portions have a radial depth dimension on the end surface of the housing on the stator core side. Is formed shallower than the opposite side, and the second cutout portion is located at a position where the projection portion that is plastically deformed in the radial depth direction at a location where the radial depth dimension is shallow inside the plurality of first cutout portions is engaged. Brushless motor with formed. The stator core is
The brushless motor according to claim 1, wherein two types of cores having different radial depth dimensions of the first notch are stacked. 3. The brushless motor according to claim 2, wherein the second notch is formed in a range radially inward from an outer periphery in the radial direction of the other core having a large depth dimension. The said notch part was formed in the position corresponding to the salient pole of the stator core outer periphery of the inner periphery of the hole formed in the center of a stator core along the circumferential direction. Brushless motor. 2. The brushless motor according to claim 1, wherein an outer periphery of a bearing disposed at a position close to the stator core is in contact with the housing only at the position of the protrusion within the range of the thickness of the stator core.

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