JP6136941B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor including a brush and a commutator.

  As a conventional technique, for example, as described in Patent Document 1, an electric motor including a brush and a commutator is known. In the prior art, in order to pass an electric current through the rotor, which is a rotating body, the brush on the stator side and the commutator on the rotor side are slidably contacted, and the brush is rectified by pressure members such as springs arranged at multiple locations. It is configured to press against the child. In the prior art, the pressure of each pressure member is prevented from affecting other pressure members by pressing the brush while each pressure member is independent.

Japanese Utility Model Publication No. 62-159155

  In the above-described conventional electric motor, there are deviations in the center of rotation caused by errors in the dimensions and shapes of the components, variations in the characteristics of the pressure members, and the like. For this reason, a deviation tends to occur in the contact pressure of each brush with respect to the commutator, and it is difficult to make the contact force uniform. As a result, in the prior art, wear of a brush having a relatively large contact pressure is more likely to progress than other brushes, so that only a specific brush may be worn early, and the product life of the electric motor is shortened. There is a problem.

  The present invention has been made to solve the above-described problems, and can suppress the deviation of the contact pressure of each brush with respect to the commutator, equalize the wear of the brush, and extend the product life. An object is to provide a possible electric motor.

An electric motor according to the present invention includes a housing, a commutator formed in a circular shape having an axis, and supported by the housing so as to be rotatable about the axis, and a plurality of contacts that are in contact with the outer peripheral surface of the commutator at positions spaced apart from each other. and brush, with can be displaced in the radial direction commutator against the housing, and a movable holder for supporting a plurality of brushes, provided on the movable holder, pressurize toward each brush on an outer circumferential surface of each commutator A plurality of pressure members . The movable holder includes a plurality of brush support portions that respectively accommodate the respective brushes so as to be displaceable in the radial direction of the commutator, and each of the pressure members, and a connecting portion that connects the brush support portions. Yes.

  According to the present invention, the movable holder that can be displaced with respect to the housing is provided, and each brush is supported by the movable holder so as to be displaceable. Even in this case, these factors can be absorbed by the displacement of the movable holder, and the contact pressure of each brush against the commutator can be equalized. Therefore, it is possible to suppress only specific brushes from being worn at an early stage, to make the wear state of each brush uniform, and to extend the product life of the electric motor.

It is sectional drawing which fractured | ruptured the electric motor by Embodiment 1 of this invention in the plane perpendicular | vertical to a central axis. In Embodiment 1 of this invention, when the rotation center of a commutator shifts | deviates, it is operation | movement explanatory drawing which shows the state which a deviation produces in the contact pressure of each brush. In Embodiment 1 of this invention, the shift | offset | difference of a rotation center is absorbed by the displacement of a movable holder, and it is operation | movement explanatory drawing which shows the state in which the contact pressure of each brush is equalized. In Embodiment 1 of this invention, it is operation | movement explanatory drawing which shows the state in which the displacement of the movable holder is restrict | limited. It is sectional drawing which looked at the electric motor by Embodiment 2 of this invention from the same position as FIG. In Embodiment 2 of this invention, when the rotation center of a commutator shifts | deviates, it is operation | movement explanatory drawing which shows the state which a deviation produces in the contact pressure of each brush. In Embodiment 2 of this invention, the shift | offset | difference of a rotation center is absorbed by the displacement of a movable holder, and it is operation | movement explanatory drawing which shows the state in which the contact pressure of each brush is equalized. In Embodiment 2 of this invention, it is operation | movement explanatory drawing which shows the state in which the displacement of the movable holder is restrict | limited.

Embodiment 1 FIG.
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. In each drawing used in this specification, common elements are denoted by the same reference numerals, and redundant description is omitted. First, FIG. 1 is a cross-sectional view of an electric motor according to Embodiment 1 of the present invention, taken along a plane perpendicular to the central axis. As shown in this figure, the electric motor 1 of this embodiment includes a housing 2, a commutator 3, a brush 4, a movable holder 5, a pressure member 6, and a holder guide portion 7.

  The housing 2 constitutes the outline of the electric motor 1 and has a cylindrical cross section. A housing, a rotor (not shown), and a rotating shaft (not shown) are accommodated inside the housing 2, and the rotating shaft is rotatably supported by the housing 2 while being fixed to the rotor. The commutator 3 is composed of, for example, two arc-shaped electrodes, is formed in a circular shape or a cylindrical shape as a whole, and is coaxially fixed to the rotation shaft. That is, the commutator 3 is configured to rotate with the rotation shaft about the axis.

  The brush 4 energizes each electrode of the commutator 3. For example, the brush 4 is formed in a cylindrical shape with a conductive material and is fixed to the housing 2 side at a position spaced from each other. Each brush 4 is arranged on both sides in the diameter direction with the commutator 3 interposed therebetween, and is in contact with the outer peripheral surface of the commutator 3 and is electrically connected to the commutator 3. When the electric motor 1 is operated, the commutator 3 rotates with the rotating shaft while being in contact with the two brushes 4. As a result, the brushes 4 that come into contact with the individual electrodes of the commutator 3 are alternately replaced, and the polarity of the current that is passed through the rotor via the brushes 4 and the commutator 3 is periodically reversed.

  The movable holder 5 is displacing itself with respect to the housing 2 while supporting each brush 4 in a displaceable manner, and is formed of a member having a substantially U-shaped cross-sectional shape. The movable holder 5 includes, for example, two brush support portions 5A formed in a substantially cylindrical shape, and a connection portion 5B that connects these brush support portions 5A. The two brush support portions 5 </ b> A are disposed on both sides in the diametrical direction with the commutator 3 interposed therebetween, and each has a recess that faces the commutator 3 and opens. In these recesses, the brush 4 is accommodated in a state in which the brush 4 can be displaced in the diameter direction of the commutator 3, and a pressure member 6 such as a spring that pressurizes the brush 4 toward the outer peripheral surface of the commutator 3 is accommodated. ing. Thereby, each brush 4 can be displaced in the diameter direction of the commutator 3 according to the positional relationship with the commutator 3 and the applied pressure of the pressure member 6 while being supported by the movable holder 5.

  The holder guide portion 7 supports the movable holder 5 so as to be displaceable, and restricts the displacement direction of the movable holder 5 only to a specific diameter direction of the commutator 3. The specific diameter direction means a direction in which the brush support portions 5 </ b> A face each other in an arbitrary diameter direction of the commutator 3. The holder guide portions 7 are provided in the housing 2 at positions on both sides in the diameter direction of the commutator 3, and extend in a cylindrical shape along the diameter direction of the commutator 3. And each holder guide part 7 is fitted with each brush support part 5A of the movable holder 5 so that displacement is possible. Thereby, the movable holder 5 can be displaced only in the specific diameter direction with respect to the housing 2.

  The electric motor 1 according to the present embodiment has the above-described configuration. Next, the operation of the movable holder 5 will be described with reference to FIGS. 2 to 4. FIG. 2 is an operation explanatory diagram illustrating a state in which a deviation occurs in the contact pressure of each brush when the rotation center of the commutator is deviated. FIG. 3 is an operation explanatory view showing a state in which the displacement of the rotation center is absorbed by the displacement of the movable holder and the contact pressure of each brush is equalized.

  First, when the electric motor 1 is operated, as shown in FIG. 2, the rotation center of the commutator 3 may deviate from the specified position in the direction of the arrow due to an unexpected factor such as a shaft tilting of the rotating shaft. is there. In this case, compared with the brush 4 on one side (for example, the right side), the brush 4 on the other side (the left side) protrudes from the brush support portion 5A, and there is a deviation in the contact pressure of each brush 4 with respect to the commutator 3. It is likely to occur. In this state, the reaction force of the contact pressure that acts on the movable holder 5 from the brush 4 via the pressure member 6 becomes uneven among the brushes 4. Thereby, the movable holder 5 is displaced together with the brush 4 and the pressure member 6 with respect to the housing 2 as shown in FIG. The displacement direction at this time is a direction (arrow direction) in which the deviation of the contact pressure is reduced.

  As a result, the positional deviation of the rotation center is absorbed by the displacement of the movable holder 5, and each brush 4 comes into contact with the commutator 3 with the same contact pressure in a state where the brush 4 protrudes equally from the brush support portion 5A. . On the other hand, FIG. 4 is an operation explanatory view showing a state in which the displacement of the movable holder is limited. The movement of the movable holder 5 in a direction other than the diameter direction of the commutator 3 is restricted by the holder guide 7. For this reason, as shown in FIG. 4, when the displacement of the center of rotation occurs in a direction different from the displacement direction of the movable holder 5, the displacement of the movable holder 5 does not occur.

  As described above, according to the present embodiment, the movable holder 5 that can be displaced with respect to the housing 2 is provided, and each brush 4 is supported by the movable holder 5 so as to be displaceable. As a result, even if there is a positional deviation of the center of rotation, characteristic variations of the pressure member 6, etc., these factors are absorbed by the displacement of the movable holder 5, and the contact pressure of each brush 4 against the commutator 3 is equalized. be able to. Therefore, it is possible to prevent only the specific brush 4 from being worn at an early stage, to make the wear state of each brush 4 uniform, and to extend the product life of the electric motor 1.

  Moreover, since the movable holder 5 is provided with two brush support parts 5A and the connection part 5B, it can support each brush 4 located in the both sides of the commutator 3 displaceably with a simple structure. In addition, since the holder guide portion 7 of the housing 2 restricts the displacement direction of the movable holder 5 to only a specific diameter direction of the commutator 3, the brush support portion 5A and the brush 4 are displaced in an unexpected direction. It is possible to suppress the rattling of these members and to stabilize the contact state between the commutator 3 and the brush 4.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. This embodiment is characterized in that a part of the movable holder also serves as a pressure member. FIG. 5 is a sectional view of the electric motor according to the second embodiment of the present invention as seen from the same position as in FIG. As shown in this figure, the electric motor 11 of the present embodiment is configured in substantially the same manner as in the first embodiment, but is movable in place of the movable holder 5, the pressure member 6 and the holder guide portion 7. A holder 15 and a holder guide 16 are provided.

  The movable holder 15 is displacing itself with respect to the housing 2 while supporting each brush 4 so as to be displaceable, and is formed in a substantially U-shape using a metal material, a resin material or the like having a spring property. . The movable holder 15 includes two brush support portions 15A disposed on both sides in the diameter direction with the commutator 3 interposed therebetween, and a connection portion 15B connecting these brush support portions 15A. Each brush support portion 15A is bent at an angle close to a right angle from both ends of the connecting portion 15B and extends to both side positions of the commutator 3, and each brush support portion 15A has a commutator 3 at the tip. The brush 4 is fixed at a position facing the.

  The movable holder 15 is attached to the housing 2 in a state in which the brush support portions 15A are elastically deformed in a direction away from each other, and the two brushes 4 have elastic forces (in the direction in which the brush support portions 15A approach each other ( It is pressurized toward the commutator 3 by an elastic restoring force). That is, in the present embodiment, at least each brush support portion 15 </ b> A of the movable holder 15 also serves as a pressure member.

  As in the first embodiment, the holder guide unit 16 supports the movable holder 15 so as to be displaceable, and restricts the displacement direction of the movable holder 15 to only a specific diameter direction of the commutator 3. The holder guide portion 16 is provided in the housing 2 at a position corresponding to the connecting portion 15B of the movable holder 15, and has a groove or a hole extending in parallel with the specific diameter direction. The connecting portion 15 </ b> B of the movable holder 15 can be displaced only in the specific diameter direction while being fitted in the groove or hole of the holder guide portion 16.

  Also in this embodiment configured as described above, the same effects as those of the first embodiment can be obtained as shown in FIGS. Here, FIGS. 6 to 8 show the same states as FIGS. 2 to 4, respectively. More specifically, first, as shown in FIG. 6, when the rotation center of the commutator 3 is shifted and a deviation occurs in the contact pressure of each brush 4, the movable holder 15 changes the deviation as shown in FIG. It is displaced in the direction of decreasing (arrow direction). As a result, the displacement of the rotation center is absorbed by the displacement of the movable holder 15, and the contact pressure of each brush 4 against the commutator 3 can be equalized.

  Further, as shown in FIG. 8, the holder guide portion 16 suppresses the brush support portion 15 </ b> A and the brush 4 from being displaced in an unexpected direction and the occurrence of rattling in these members. The contact state with the brush 4 can be stabilized. Furthermore, according to the present embodiment, since at least each brush support portion 15A of the movable holder 15 also serves as a pressure member, the number of parts of the electric motor 11 can be reduced and the structure can be simplified. it can. Note that the portion of the movable holder 15 that also serves as the pressure member may be only the brush support portion 15A, or the entire movable holder 15 may be made of an elastic material, and the whole may also serve as the pressure member.

DESCRIPTION OF SYMBOLS 1,11 Electric motor, 2 Housing, 3 Commutator, 4 Brush, 5, 15 Movable holder, 5A Brush support part, 15A Brush support part (pressure member), 5B, 15B Connecting part, 6 Pressure member, 7, 16 Holder guide

Claims (4)

A housing;
A commutator formed in a circular shape having an axis, and supported rotatably about the axis by the housing;
A plurality of brushes that contact the outer peripheral surface of the commutator at positions spaced apart from each other;
Together it is displaceable in the radial direction of the commutator against the housing, and a movable holder for supporting a plurality of brushes,
A plurality of pressure members the provided on the movable holder, that pressurize toward the the outer circumferential surface of each of the commutator and the brushes,
Equipped with a,
The movable holder is
Each of the brushes is housed so as to be displaceable in the radial direction of the commutator, and a plurality of brush support portions each housing the pressure members,
A connecting portion connecting the brush support portions ;
An electric motor. A housing;
A commutator formed in a circular shape having an axis, and supported rotatably about the axis by the housing;
Two brushes arranged on both sides in the diameter direction across the commutator and in contact with the outer peripheral surface of the commutator;
A movable holder that is displaceable in a radial direction of the commutator with respect to the housing and supports the two brushes;
Two pressurizing members provided on the movable holder and pressurizing each brush toward the outer peripheral surface of the commutator;
With
The movable holder is
Two brush support portions that are arranged on both sides in the diameter direction across the commutator, respectively accommodate the brush so as to be displaceable in the radial direction of the commutator, and accommodate the pressure members, respectively .
A connecting portion connecting the brush support portions;
Electric motor Ru equipped with. 3. The electric motor according to claim 1 , wherein the housing is provided with a holder guide portion that supports the movable holder so as to be displaceable and restricts a displacement direction of the movable holder only in a radial direction of the commutator. motor. The holder guide portion extends along the radial direction of the commutator,
The electric motor according to claim 3, wherein the movable holder is fitted to the holder guide portion so as to be displaceable along a radial direction of the commutator.

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