JP4724966B2 - motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor used for a drum drive in a copying machine or the like, and a bearing housing thereof.
[0002]
[Prior art]
Conventionally, for example, a brushless motor is known as a motor used for the above-described applications. 3A and 3B are diagrams showing the configuration of such a conventional brushless motor. FIG. 3A is a front longitudinal sectional view, and FIG. 3B is a bottom view. In the figure, reference numeral 1 denotes an attachment plate that serves as a base for attachment to a required place in an application device such as the copying machine. The substantially cylindrical housing 3 passes through the mounting hole 2 formed at the lower end of the mounting plate 1 and is fixed by caulking at the peripheral edge.
[0003]
A shaft 9 is rotatably supported on the inner surface side of the housing 3 via a pair of upper and lower ball bearings 7 and 8. A cup-shaped rotor 10 is fixed to the upper end portion of the shaft 9 led out from the upper end of the housing 3 by press-fitting or the like, and the rotor 10 rotates integrally around the shaft 9. An annular rotor magnet 11 is fitted and fixed to the inner peripheral surface of the outer peripheral wall of the rotor 10.
[0004]
On the other hand, on the outer peripheral surface of the housing 3, a stator 12 in which a stator coil 14 is wound around a stator core 13 is fitted and fixed so as to face the rotor magnet 11 with a slight gap, and is fixed by screws 17. ing. The ball bearing 7 is held so as to be sandwiched between the inner peripheral portion of the rotor 10 on the upper surface of the inner ring and the step portion of the housing 3 on the lower surface of the outer ring. Further, the ball bearing 8 is held so as to be sandwiched between a disc spring 24a at a step portion of the housing 3 on the upper surface of the outer ring and a stopper ring 24 on the lower surface of the inner ring. A circuit board 20 on which required electronic components are mounted and a rotor 10 rotation drive circuit and a coil current control circuit for the stator 12 are formed is fixed to the flange portion 19 of the housing 3 with screws 5. Yes.
[0005]
The circuit board 20 is also fixed to the mounting plate 1 with screws 6. That is, a tongue piece 1 b is provided at one location on the periphery of the mounting plate 1, and the circuit board 20 is fixed to the mounting plate 1 with the screw 6 in the screw hole 1 ba opened therein. In addition, tongue pieces 1c are provided at the four corners of the mounting plate 1, and the mounting plate 1 is attached to the applied device side through holes 1ca opened therein.
[0006]
Screw teeth 21 are integrally formed at the lower end portion of the shaft 9 led out from the housing 3. When this brushless motor is attached to the application device, a transmission gear (not shown) such as a speed reduction mechanism of the application device is meshed with and connected to the screw teeth 21. The brushless motor is generated between the stator 12 and the rotor magnet 11 by supplying a drive current (excitation current) from an external drive power source to the stator coil 14 of the stator 12 via the control circuit of the circuit board 20. A rotational force is generated in the rotor 10 by the attractive force and the repulsive force due to the magnetic action, and the rotational force of the rotor 10 is transmitted to the rotational driving load of the application device through the screw teeth 21 and the transmission gear of the shaft 9.
[0007]
[Problems to be solved by the invention]
However, as described above, the housing 3 requires various irregularities for mounting the pair of ball bearings 7 and 8, the stator 12, and the mounting plate 1. Therefore, in the conventional configuration, the housing 3 is made of zinc. Molding is performed by die casting or aluminum die casting, cutting, etc. to increase dimensional accuracy, and this has been a cause of high costs associated with the production of the motor. Further, this molding method cannot easily reduce the thickness because it is difficult to reduce the thickness.
[0008]
In view of the above problems, an object of the present invention is to provide a motor that can be manufactured at a lower cost than the prior art and that can achieve a reduction in size.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a substantially cylindrical housing, a mounting plate for holding the housing, a sleeve bearing attached to the inner peripheral surface of the housing, and an inner periphery of the sleeve bearing are inserted. A shaft rotatably supported by the housing via the sleeve bearing, a rotor having a rotor magnet and fixed to one end of the shaft, and an outer peripheral surface of the housing facing the rotor magnet And a stator that is externally fitted and fixed to the housing by bonding or press-fitting to the housing, the mounting plate includes a mounting hole into which a lower end portion of the housing is fitted, and the housing is formed by plastic working a sheet metal. An outer step portion in which the stator is in axial contact with the outer peripheral surface of the housing, and a lower end portion of the housing at an axial lower end of the housing Is bent in the radial direction, and includes a plurality of hook-shaped portions that contact a flat surface around the mounting hole, and a plurality of hanging portions that contact the inner surface of the mounting hole, and the plurality of hook-shaped portions, A plurality of the hanging portions can be alternately arranged in the circumferential direction.
[0010]
A substantially cylindrical housing; a mounting plate for holding the housing; a sleeve bearing attached to the inner peripheral surface of the housing; and the housing being inserted into the inner periphery of the sleeve bearing, through the sleeve bearing. A shaft rotatably supported on the rotor, a rotor having a rotor magnet fixed to one end portion of the shaft, and being fitted and fixed to the outer peripheral surface of the housing so as to face the rotor magnet by adhesion or press-fitting. In the motor comprising the stator, the inner peripheral surface of the sleeve bearing has upper and lower sliding surfaces that slidably support the shaft at both axial end portions excluding the axial center portion. A bearing outer peripheral surface corresponding to a radial direction of the axial center portion of the sleeve bearing is fitted and fixed to an inner peripheral surface of the housing, and the upper and lower surfaces of the sleeve bearing are fixed. Only the bearing outer circumferential surface corresponding to the radial direction of the sliding surface of the lower located is interference relative to the housing, wherein the housing includes a major inner surface which is formed on the inner peripheral surface of the axially downward, A small inner diameter surface formed smaller in diameter than the large inner diameter surface on an inner peripheral surface axially above the large inner diameter surface, and an inner step formed at a boundary between the large inner diameter surface and the small inner diameter surface The sleeve bearing has an outer diameter of the bearing outer peripheral surface corresponding to a radial direction of the central portion in the axial direction, an outer diameter of the bearing outer peripheral surface corresponding to a radial direction of the upper sliding surface. And the large inner diameter surface corresponds to the lower sliding surface via a gap in the radial direction, and the sleeve bearing is press-fitted from the inner step portion into the small diameter portion. It is characterized by. Moreover, the taper part which the outer diameter of the said bearing outer peripheral surface corresponding to the radial direction of the said sliding surface of the said upper side of the said sleeve bearing shrinks toward the said upper side can be provided.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience of explanation, portions having the same functions as those of the conventional example are denoted by the same reference numerals. 1A and 1B are diagrams showing a configuration of a motor according to an embodiment of the present invention. FIG. 1A is a front longitudinal sectional view, and FIG. 1B is a bottom view. Here, an example of a brushless motor is shown as in the conventional example. In the figure, reference numeral 1 denotes an attachment plate that serves as a base for attachment to a required place in an application device such as the copying machine. FIG. 4 is an external perspective view schematically showing the housing (described later) of FIG.
[0014]
The substantially cylindrical housing 3 formed by plastic processing of a sheet metal is formed by bending its lower end portion radially outward at a plurality of surrounding locations (in this embodiment, three locations at equal intervals in the circumferential direction). It has a hook-shaped part 3a, and a hanging part 3b that hangs down at a plurality of places around the lower end part (in the present embodiment, they are respectively located in the middle of the hook-shaped parts 3a adjacent to each other at three places at equal intervals in the circumferential direction). This constitutes the motor side mounting portion. Further, an outer step portion 3c formed by drawing is provided on the outer peripheral surface, and the outer diameter is smaller in the upper portion than in the lower portion with the outer step portion 3c as a boundary. Further, an inner step portion 3c similarly formed by drawing is provided on the inner peripheral surface. The inner step portion 3c serves as a boundary, and the inner diameter is smaller than the lower portion.
[0015]
A screw hole 3aa is formed in the bowl-shaped part 3a, and the housing 3 is axially positioned with respect to the mounting plate 1 by screwing it with a screw 5 in accordance with the hole 1a formed in the mounting plate 1. Attached to go. At this time, the drooping portion 3b passes through the mounting hole 2 opened inward so as to be surrounded by the hole 1a of the mounting plate 1, and is positioned in the radial direction by contacting the inner peripheral surface thereof.
[0016]
When the hole diameter of the mounting hole 2 is larger than the overall outer diameter of the plurality of hanging parts 3b, the hanging part 3b may be bent outward in accordance with this, and conversely, the hole diameter of the mounting hole 2 is small. In this case, the drooping portion 3b may be bent inward according to this. Similarly, in the bowl-shaped part 3a, the length of the bowl-shaped part 3a may be changed in accordance with the change of the hole diameter of the mounting hole 2. Thus, since the drooping part 3b and the hook-shaped part 3a are formed by plastic working, even if there are various changes in the shape of the mounting plate 1, it is possible to respond more flexibly than conventional die casting. Is possible.
[0017]
A substantially cylindrical oil-impregnated metal sleeve bearing 7 is press-fitted into the small inner diameter portion located above the inner step portion 3d, and the large inner diameter portion located below forms a minute gap with the sleeve bearing 7. Through this, the shaft 9 is rotatably supported. A cup-shaped rotor 10 is fixed to the upper end portion of the shaft 9 led out from the upper end of the housing 3 by press-fitting or the like, and the rotor 10 rotates integrally around the shaft 9. An annular rotor magnet 11 is fitted and fixed to the inner peripheral surface of the outer peripheral wall of the rotor 10.
[0018]
On the other hand, a stator core 13 is placed on the outer step portion 3c, and a stator 12 having a stator coil 14 wound around the stator core 13 on a small outer diameter portion located above the outer step portion 3c is a rotor. The magnet 11 is externally fitted and fixed by bonding or press-fitting in a position facing the magnet 11 with a slight gap. The upper surface of the sleeve bearing 7 holds the rotating rotor 10 while sliding. The lower surface of the sleeve bearing 7 is supported by the shaft 9 via a sliding ring 22, a washer 23, and a stopper ring 24.
[0019]
In addition, tongue pieces 1b are provided at four locations on the periphery of the mounting plate 1, and the circuit board 20 is fixed to the mounting plate 1 with screws 6 in the screw holes 1ba opened therein. The circuit board 20 is formed by mounting required electronic components to form a rotation drive circuit for the rotor 10 and a coil current control circuit for the stator 12. In addition, tongue pieces 1c are provided at the four corners of the mounting plate 1, and the mounting plate 1 is attached to the applied device side through holes 1ca opened therein. The mounting plate 1 is provided to make it easy to attach the motor to the application device. Instead of providing a plate independent from the application device like the mounting plate 1, one of the chassis constituting the application device is used. The motor may be directly attached to an applicable device without using the mounting plate 1 as a mounting portion.
[0020]
Screw teeth 21 are integrally formed at the lower end portion of the shaft 9 led out from the housing 3. When this brushless motor is attached to the application device, a transmission gear (not shown) such as a speed reduction mechanism of the application device is meshed with and connected to the screw teeth 21. The brushless motor is generated between the stator 12 and the rotor magnet 11 by supplying a drive current (excitation current) from an external drive power source to the stator coil 14 of the stator 12 via the control circuit of the circuit board 20. A rotational force is generated in the rotor 10 by the attractive force and the repulsive force due to the magnetic action, and the rotational force of the rotor 10 is transmitted to the rotational driving load of the application device through the screw teeth 21 and the transmission gear of the shaft 9.
[0021]
As described above, in the present embodiment, the housing 3 is formed by sheet metal plastic processing, so that the material cost is low and the processing time can be shortened as compared with the conventional die casting method. In addition, the cost can be reduced by easily adapting to various shape changes, and the wall thickness can be reduced. Further, by fixing the stator 12 to the housing 3 by adhesion or press fitting, the conventional screws and screw holes are not required, so that the thickness of the housing 3 can be reduced.
[0022]
As a result, the outer diameter of the housing 3 can be smaller than in the prior art, so that the inner diameter of the stator 12 can also be reduced. As a result, the stator core 13 of the stator 12 can be enlarged and the winding amount of the stator coil 14 can be increased (improvement of the line area ratio). Therefore, if the motor size is the same, a stronger output can be obtained. The magnetic characteristics are improved compared to the conventional one. Alternatively, while the stator 12 and the rotor magnet 11 have substantially the same magnetic characteristics as the conventional one, the motor can be downsized accordingly.
[0023]
As shown in FIG. 1A, the sleeve bearing 7 has sliding surfaces 7a and 7b on the upper and lower portions of the inner peripheral surface, respectively. These are surfaces that protrude slightly inward in the radial direction as compared with the central portion, that is, surfaces having a small inner diameter, and these surfaces slide with respect to the shaft 9. A tapered portion t that decreases in diameter toward the upper end is provided at the upper portion of the outer peripheral surface of the sleeve bearing 7. When such a sleeve bearing 7 is press-fitted into the upper small-diameter portion from the inner step portion 3d of the housing 3 as described above, the tightening margin comes only in the central portion and does not reach the upper and lower portions. The moving surfaces 7a and 7b are not deformed by an extra force applied by press-fitting.
[0024]
Next, another embodiment of the present invention will be described. The motor of this embodiment is a substantially cylindrical housing formed by plastic working a sheet metal, such as the housing 3 constituting the motor of the previous embodiment. The bearing is axially positioned by projecting radially inward. Such a projecting portion is cut in the circumferential direction of the housing, so that this portion becomes a bearing contact surface perpendicular to the axial direction, and can be formed with high accuracy.
[0025]
A combination of ball bearings is suitable for a housing having such a protrusion. This is because the ball bearing needs to be preloaded in order to improve the bearing characteristics, and the mounting position needs to be set with high accuracy. It is desirable that three or more protruding portions are provided at equal intervals in the circumferential direction of the housing with respect to one bearing. A specific configuration of such a protrusion provided on the housing will be described below.
[0026]
FIG. 2 is a perspective view showing various configurations of protrusions provided on the housing. In the figure, since a plurality of protrusions having the same shape are provided equally in the circumferential direction, only one of them is shown, and the inner peripheral surface of the housing is partially illustrated. The arrow direction is the axial direction and the vertical direction. The protrusion p shown in FIG. 5A is formed by providing one notch 3e in the circumferential direction of the housing 3 and pushing the lower side (or upper side) radially inward. At this time, the protrusion p is substantially triangular when viewed in the axial direction. And the cut side of the protrusion part p becomes the substantially triangular bearing contact surface 3f, and this can be used as positioning of the bearing.
[0027]
The protrusion p shown in FIG. 2B is formed by providing a pair of upper and lower cuts 3e in the circumferential direction of the housing 3 and pushing the gap inward in the radial direction. At this time, the protrusion p is rectangular when viewed in the axial direction. And the upper and lower ends which are the notch sides of the protrusion part p become the rectangular bearing contact surface 3f, and this can be used as positioning of a bearing. The protrusion p may be semicircular when viewed in the axial direction.
[0028]
The projecting portion p shown in FIG. 2C is provided with a pair of upper and lower cuts 3e in the circumferential direction of the housing 3, and further provided with cuts 3g in the axial direction so as to connect the two cuts. Is pushed inward in the radial direction. Here, the upper and lower ends on the notch 3e side of the projecting portion p are rectangular bearing contact surfaces 3f, which can be used for positioning the bearing. In this case, since the leading end of the projecting portion p is a free end, the tensile force applied to the root portion of the projecting portion p is reduced as compared with the cases of (a) and (b). Distortion is unlikely to occur and can be projected more radially inward.
[0029]
When the protrusions as shown in the above (a) to (c) are used for positioning the bearings, when there are a pair of upper and lower bearings, the protrusions may be provided for each bearing, and (b) Alternatively, if the protrusions in (c) are used, the bearing contact surfaces at the upper and lower ends of one protrusion can be used for each bearing. Further, even when there are a pair of upper and lower bearings, the protrusions as shown in the above (a) to (c) may be provided for positioning only on one of the bearings.
[0030]
Providing the protrusions as described above can be performed within the processing step of the housing, and it is not necessary to provide a separate positioning component, thereby further reducing the cost. In addition, in order to make it the structure which attaches the motor provided with the housing which has such a protrusion part to an applicable apparatus, it is needless to say that the motor side attaching part as demonstrated in FIG. 1 may be provided.
[0031]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a motor that can be manufactured at a lower cost than the prior art and that has improved magnetic characteristics or reduced the size of the motor.
[0032]
Moreover, the motor provided with the housing which can perform positioning of the axial direction of a bearing with high precision by simple structure can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a motor according to an embodiment of the present invention.
FIG. 2 is a perspective view showing various configurations of protrusions provided on a housing in a motor according to another embodiment of the present invention.
FIG. 3 is a diagram showing a configuration of a conventional brushless motor.
4 is an external perspective view schematically showing the housing of FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Mounting plate 2 Mounting hole 3 Housing 3a Gutter-shaped part 3b Hanging part 3c Outer step part 3d Inner step part 5,6 Screw 7 Sleeve bearing 9 Shaft 10 Rotor 11 Rotor magnet 12 Stator 13 Stator core 14 Stator coil 20 Circuit board 21 Screw teeth 22 Slide ring 23 Washer 24 Stopper ring

Claims (4)

A substantially cylindrical housing;
A mounting plate for holding the housing;
A sleeve bearing attached to the inner peripheral surface of the housing;
A shaft inserted through the inner periphery of the sleeve bearing and rotatably supported by the housing via the sleeve bearing;
A rotor having a rotor magnet and fixed to one end of the shaft;
In a motor provided with a stator facing and fixed to the outer peripheral surface of the housing by adhesion or press fitting facing the rotor magnet,
The inner peripheral surface of the sleeve bearing has upper and lower sliding surfaces that slidably support the shaft at both axial end portions excluding the central portion in the axial direction,
A bearing outer peripheral surface corresponding to a radial direction of the axial central portion of the sleeve bearing is fitted and fixed to an inner peripheral surface of the housing;
A tightening margin for the housing is located only on the bearing outer peripheral surface corresponding to the radial direction of the sliding surface on the upper side and the lower side of the sleeve bearing,
The housing has a large inner diameter surface formed on an inner peripheral surface below in the axial direction, a small inner diameter surface formed on the inner peripheral surface axially above the large inner diameter surface and smaller in diameter than the large inner diameter surface, An inner step formed at the boundary between the large inner diameter surface and the small inner diameter surface,
The sleeve bearing is formed such that the outer diameter of the bearing outer peripheral surface corresponding to the radial direction of the upper sliding surface is smaller than the outer diameter of the bearing outer peripheral surface corresponding to the radial direction of the central portion in the axial direction. And
The large inner diameter surface corresponds to the radial direction through a gap in the lower sliding surface,
The motor according to claim 1, wherein the sleeve bearing is press-fitted into the small diameter portion from the inner stepped portion.   The mounting plate includes a mounting hole into which a lower end portion of the housing is fitted,
  The housing is formed by plastic processing of a sheet metal, and an outer step portion in which the stator is in axial contact with the outer peripheral surface of the housing, and a lower end portion of the housing is bent in a radial direction at an axial lower end of the housing. 2. The apparatus according to claim 1, further comprising: a plurality of hook-shaped portions that contact a flat surface around the mounting hole; and a plurality of hanging portions that contact the inner surface of the mounting hole. motor.   The motor according to claim 2, wherein the plurality of hook-shaped portions and the plurality of hanging portions are alternately arranged in the circumferential direction. 4. The taper portion according to claim 1, wherein an outer diameter of the bearing outer peripheral surface corresponding to a radial direction of the sliding surface on the upper side of the sleeve bearing is provided with a diameter decreasing toward the upper side. The motor according to Crab .

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