WO2020059512A1 - Coreless motor with flat brush - Google Patents

Abstract

This coreless motor with a flat brush comprises: an armature; a magnet; a housing; a bracket; a brush; a brush holder; cover plate; a thermally conductive molded body; and a heat insulating material. The armature is integrally molded with a shaft, a plurality of coils, and a commutator using a mold resin. The magnet is positioned facing the armature. The housing holds the magnet. The bracket is positioned facing the magnet, sandwiching the armature and a void. The brush holder includes a groove in which the brush is able to move. The cover plate covers the groove. The thermally conductive molded body is positioned between the bracket and the cover plate. The heat insulating material is positioned between the armature and the bracket. The heat insulating material has lower thermal conductivity than air.

Description

Flat type brushless coreless motor

The present invention relates to a flat brushless coreless motor used for a radiator cooling fan used for a motorcycle or an automobile or a condenser cooling fan used for a car air conditioner in a vehicle-mounted field.

In recent years, the electrification of vehicles is progressing, and the number of electric motors mounted on vehicles such as motorcycles and automobiles is increasing year by year. Along with this, there has been a strong demand for smaller and lighter electric motors in terms of size and weight. In particular, a flat brushless coreless motor that is also used as a radiator cooling fan used for a motorcycle is required to be thinner in order to fit in a narrow space.

Every year, there is an increasing demand for longer life of electric motors, especially commutator motors. However, as described above, the electric motor is often mounted in a narrow space, and it is difficult for heat to escape. For this reason, in the electric motor, the ambient temperature surrounding the electric motor tends to increase, and the temperature of the portion where the current is rectified tends to increase. This contributes to shortening the life of the electric motor, particularly the commutator motor.

Therefore, in the commutator motor, it is required to prevent the brush constituting the portion for rectifying the current from being oxidized and deteriorated, thereby preventing abrasion from being promoted. Therefore, there is a strong demand for commutator motors to have improved heat radiation so that the brushes of the commutator motor do not exceed a certain temperature.

Conventionally, the following structure has been proposed for the purpose of improving heat radiation as a measure against the temperature rise of the brush.

Patent Document 1 describes a structure in which a rectangular space, that is, an air groove is provided on the outer periphery of a brush holder. According to this configuration, it is shown that the heat radiation of the brush is improved by increasing the contact area between the brush and the air.

Patent Document 2 describes the following structure. That is, the pigtail connected to the brush is connected to the pigtail. An electrically insulating and thermally conductive sealing material is interposed between the plate and the bracket, which form a conductive portion for the brush. With this configuration, a heat dissipation structure is provided to allow heat to escape from the brush to the bracket side.

However, the technique described in Patent Literature 1 is a structure in consideration of maintaining the motor size, particularly the size of the brush holder. In this structure, the space that the air space can take is too narrow. Therefore, in this structure, it is considered that heat easily stays in the air layer and it is difficult to obtain a heat radiation effect. Conversely, if the size of the air layer is set to a sufficient heat radiation effect by using this structure, the motor size may be increased.

技術 When the technique described in Patent Document 2 is applied to a flat type brushless coreless motor, the bracket receives radiant heat from the armature. Therefore, in this structure, it is considered that a sufficient heat radiation effect cannot be obtained only by forming a heat path to the bracket.

Japanese Utility Model Laid-Open No. 1-071955 JP 2008-236979 A

The present invention solves the conventional problems. The present invention provides a flat brushless coreless motor with a brush that ensures the reliability of the brush and has little reduction in life due to a rise in temperature even when the flat brushless coreless motor is used in a high temperature and wide temperature range. The purpose is to:

The present invention is provided with the following configuration in order to efficiently radiate self-heating generated in the electric motor. That is, in the electric motor, the bracket as the heat radiating member and the cover plate are in contact with each other via the heat conductive molded body. Further, in the electric motor, a heat insulating material is located between the armature, which is a heating element, and the bracket. Thermal insulation has a lower thermal conductivity than air. Therefore, a heat path is formed in the electric motor for transmitting the heat of the brush to the bracket via the cover plate and the heat conductive molded body while preventing radiant heat from the armature.

Specifically, the flat type brushless coreless motor according to the first aspect of the present invention includes an armature, a magnet, a housing, a bracket, a brush, a brush holder, a cover plate, and a heat conductive molded body. And a heat insulating material.

The armature integrally forms a shaft, a plurality of coils, and a commutator with a mold resin. The shaft extends in the axial direction. The plurality of coils are attached in a circumferential direction about the axis. The commutator has a commutator piece connected to each of the plurality of coils.

The magnet is located facing the armature. The housing holds the magnet. The bracket is located to face the magnet with the armature and the gap therebetween. The brush contacts the commutator. The brush holder includes a groove in which the brush can move. The cover plate covers the groove. The heat conductive molding is located between the bracket and the cover plate. The heat insulating material is located between the armature and the bracket. Thermal insulation has a lower thermal conductivity than air.

According to the first aspect of the present invention, it is possible to secure electrical insulation and to prevent a short circuit between the cover plate and the bracket adjacent to the brush. That is, according to this aspect, a heat insulating material having a lower thermal conductivity than air can be in contact with the bracket between the bracket and the armature without contacting the armature. Therefore, according to this aspect, it is possible to prevent the bracket from receiving the heat generated by the armature that is the heat generating portion. Therefore, the coreless motor of the present embodiment can efficiently insulate heat. For this reason, the coreless motor of this aspect can effectively radiate the heat of the brush from the bracket, so that the temperature of the brush can be reduced. Therefore, in the coreless motor according to the present embodiment, the wear resistance of the brush is improved, and the life of the motor can be extended.

The heat insulating material is preferably formed by impregnating a sheet-like material to be impregnated (for example, a nonwoven fabric) with a heat insulating material and sandwiching the film-like or sheet-like resin. The heat insulating material is used by punching into an arbitrary shape.

Further, it is preferable that the thermally conductive molded body has rubber elasticity. Thus, the thermally conductive molded body can suppress vibration and noise with backlash generated by the clearance between the brush and the brush holder due to a damping effect, and can improve quietness.

と し て As a second aspect of the present invention, it is preferable that the heat insulating material is impregnated with a heat insulating material containing silica xerogel (Silica @ Xerogel) having high heat resistance.

According to the second aspect of the present invention, the coreless motor of this aspect can ensure sufficient heat resistance in a high-temperature environment such as an on-vehicle use. Therefore, according to the present embodiment, the coreless motor of the present embodiment can obtain a heat insulating structure excellent in cost and moldability.

と し て As a third aspect of the present invention, it is preferable that the thermally conductive molded body is a silicone rubber or an acrylic rubber.

According to the third aspect of the present invention, in a high temperature environment, the coreless motor of the present aspect can ensure high reliability and heat dissipation.

FIG. 1A is a bottom view of the motor according to the first embodiment of the present invention. FIG. 1B is a side view of the motor according to the first embodiment of the present invention. FIG. 1C is a top view of the motor according to the first embodiment of the present invention. FIG. 2 is an exploded view of the motor according to the first embodiment of the present invention. FIG. 3 is a sectional view of the motor according to the first embodiment of the present invention. FIG. 4 is a sectional view of a conventional motor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and tables. It should be noted that each of the embodiments described below shows a preferred specific example of the present invention. Therefore, the numerical values, constituent elements, arrangement positions and connection forms of the constituent elements, steps and the order of the steps, and the like shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims that indicate the highest concept of the present disclosure are described as arbitrary components.

図 Each drawing is a schematic diagram, and is not necessarily strictly illustrated. In each of the drawings, substantially the same components are denoted by the same reference numerals, and redundant description will be omitted or simplified.

扁 Flat brushless coreless motors used around the engine room of vehicles are used, for example, in radiator cooling fans or condenser cooling fans for car air conditioners. In the following embodiments, a flat brushless coreless motor for a radiator cooling fan used in a vehicle will be described as an example. In the following description, a flat brushless coreless motor may be simply referred to as a motor.

(Embodiment 1)
FIG. 1A is a bottom view of the motor according to Embodiment 1 of the present invention. FIG. 1B is a side view of the motor according to Embodiment 1 of the present invention. FIG. 1C is a top view of the motor according to Embodiment 1 of the present invention. FIG. 2 is an exploded view of the motor according to the first embodiment of the present invention. FIG. 3 is a sectional view of the motor according to the first embodiment of the present invention. In FIG. 3, the right side shows an enlarged part of the motor. FIG. 4 is a sectional view of a conventional motor. In FIG. 4, the right side shows an enlarged part of a conventional motor.

～ As shown in FIGS. 1 to 3, the flat brushless coreless motor 100 includes a housing 10, a bracket 11, a brush holder 15, an armature 14, and the like.

The magnetic circuit included between the housing 10 and the bracket 11 will be described.

The housing 10 is formed into a substantially thin cup shape by processing an iron plate. Similarly, a flange used for assembling with the bracket 11 is formed by processing an iron plate. The housing 10 and the bracket 11 are fitted and fixed by means such as press-fitting, screwing, or bonding with a sealant. On the output shaft side of the housing 10, a bearing 13a is held. Inside the housing 10, a magnet 12 made of a permanent magnet is adhered and fixed. The housing 10 and the bracket 11 include an armature 14 via a gap. The magnet 12 has magnetic poles of N poles and S poles alternately, and is magnetized, for example, with four poles or six poles.

The armature 14 has a configuration in which a shaft 14a, a commutator 14b, and a coil 14c are integrally formed with a mold resin 14d. The plurality of coils 14c wound with copper wires are connected to commutator pieces of the commutator 14b by fusing or the like. In order to make the drawings easy to understand, details of the commutator pieces are not shown. The armature 14 is located between the magnet 12 and the bracket 11 with a gap therebetween. The bracket 11 also serves as a back yoke as a magnetic circuit. With this configuration, the armature 14 forms a magnetic circuit by the magnet 12 and the bracket 11 that are located opposite to each other. The bracket 11 includes a bearing receiving portion into which the bearing 13b is inserted. The bearing receiving portion holds and fixes the bearing 13b.

The power supply unit included between the brush holder 15 and the bracket 11 will be described.

The brush holder 15 is formed of a thermosetting resin so as to withstand high temperatures. The brush holder 15 includes a groove 15d in which the brush 15a can move. The brush 15a supplies power to the commutator 14b by rubbing against and contacting the commutator 14b. The cover plate 15b covers the groove 15d. In the present embodiment, the cover plate 15b is made of metal and covers the groove 15d so as to cover it. The brush holder 15 forms a brush box with the cover plate 15b covering the groove 15d. A spring 15c for applying pressure to the brush 15a is incorporated in the brush box, that is, in a space surrounded by the brush holder 15 and the cover plate 15b. The spring 15c applies pressure to the brush 15a to stabilize the operation in which the brush 15a slides on and contacts the commutator 14b. The brush 15a is connected to an external power supply harness (not shown) via a pigtail attached to the brush 15a. The brush holder 15 and the bracket 11 are fixed by means such as screwing.

断 熱 A heat insulating material 30 is located between the bracket 11 and the armature 14. The heat insulating material 30 thermally separates radiant heat (the hatched arrow in FIG. 3) from the armature 14 serving as a heat generating portion. The heat insulating material 30 is formed by sandwiching a sheet of nonwoven fabric impregnated with a heat insulating material with a film. A sheet-like material to be impregnated made of glass wool is used for the nonwoven fabric. As the heat insulating material, silica xerogel shown in (Table 1) is used. The silica xerogel used in the present embodiment has a thermal conductivity of about 0.017 W / m · K. For example, a glass cloth is used for the film. The film in which such a heat insulating material is sandwiched is punched into an arbitrary shape. Table 1 compares the properties of heat insulating materials formed from various materials.

れ ば Using this material and structure, it is possible to achieve a thickness reduction of about 0.1 mm to 0.3 mm. For this reason, it becomes possible to enclose the heat insulating material 30 between the bracket 11 and the armature 14, which usually have a gap of about 0.5 mm to 1 mm. The heat insulating material 30 has a heat conductivity smaller than the heat conductivity of air (about 0.026 W / m · K). The heat insulating material 30 having such features has a high heat insulating effect.

The heat (solid arrow in FIG. 3) of the brush 15 a, which is a power supply unit and the other heating element, is transmitted to the bracket 11 via the heat conductive molded body 20 via the metal cover plate 15 b. . The heat transmitted to the bracket 11 is radiated from the bracket 11 to the outside. The heat conductive molded body 20 has electrical insulation, heat conductivity, and rubber elasticity.

At this time, the heat of the brush 15 a can be sufficiently transmitted to the bracket 11 by using the heat conductive molded body 20 and the heat insulating material 30 together. Therefore, it is possible to prevent adverse effects such as the temperature of the brush 15a further increasing due to the reverse flow of heat from the armature 14, which is considered when only the heat conductive molded body 20 is used.

従 来 As a comparative example, a conventional motor 101 will be described. In the conventional motor 101 shown in FIG. 4, there is no heat insulating material corresponding to the heat insulating material 30 of the present embodiment. Therefore, in the conventional motor 101, heat from the armature 114 is transmitted to the brush 115a through the bracket 111, as indicated by the hatched arrow in FIG. That is, the conventional motor 101 suffers from an adverse effect such as a further increase in the temperature of the brush 115a.

On the other hand, in the motor 100 according to the present embodiment, the heat conductive molded body 20 has rubber elasticity. Therefore, the motor 100 in the present embodiment suppresses rattling vibration and noise due to the clearance generated between the brush 15a and the brush holder 15 due to the damping effect of the thermally conductive molded body 20. Motor 100 in the present embodiment has improved quietness.

As described above, the flat type brushless coreless motor 100 according to the present embodiment includes the armature 14, the magnet 12, the housing 10, the bracket 11, the brush 15a, the brush holder 15, and the cover plate 15b. , A heat conductive molded body 20 and a heat insulating material 30.

The armature 14 has a shaft 14a, a plurality of coils 14c, and a commutator 14b, which are integrally formed with a mold resin 14d. The shaft 14a extends in the direction of the axis C. The plurality of coils 14c are attached in a circumferential direction about the axis C. The commutator 14b has a commutator piece connected to each of the plurality of coils 14c.

The magnet 12 is located so as to face the armature 14. The housing 10 holds a magnet 12. The bracket 11 is positioned to face the magnet 12 with the armature 14 and the gap therebetween. The brush 15a contacts the commutator 14b. The brush holder 15 includes a groove 15d in which the brush 15a can move. The cover plate 15b covers the groove 15d. The heat conductive molding 20 is located between the bracket 11 and the cover plate 15b. The heat insulating material 30 is located between the armature 14 and the bracket 11. The heat insulating material 30 has a lower thermal conductivity than air.

With this, by using the flat type brushless coreless motor 100 according to the present embodiment, electrical insulation can be ensured and a short circuit between the cover plate 15b adjacent to the brush 15a and the bracket 11 can be prevented. Further, by using motor 100 according to the present embodiment, it is possible to prevent heat generated by armature 14 serving as a heat generating portion from being received by bracket 11. Therefore, the motor 100 according to the present embodiment can be efficiently insulated. Therefore, the motor 100 according to the present embodiment can effectively radiate the heat of the brush 15a from the bracket 11. Therefore, motor 100 according to the present embodiment can lower the temperature of brush 15a. Therefore, the motor 100 according to the present embodiment has improved wear resistance and can have a longer motor life.

断 熱 Moreover, it is preferable that the heat insulating material 30 is impregnated with a heat insulating material containing silica xerogel.

Thus, the flat brushless coreless motor according to the present embodiment can secure sufficient heat resistance for use in a high-temperature environment such as in-vehicle use.

By using the motor of the present embodiment, when the motor is used at a high temperature, the reliability of the brush is secured, and the life of the brushless motor due to the temperature rise is small, and the flat brushless coreless motor with high quietness is realized. it can.

(Embodiment 2)
In Embodiment 2 of the present invention, the heat conductive molded body 20 shown in FIG. 3 is made of silicone rubber. Note that the thermally conductive molded body 20 may be made of acrylic rubber.

(Table 2) is a table showing characteristics of the thermally conductive molded body 20 molded using various materials.

As shown in (Table 2), when the heat conductive molded body 20 is formed using silicone rubber or acrylic rubber, the heat conductive molded body 20 having heat resistance that can withstand even in a high temperature environment such as in-vehicle use is obtained. be able to.

The thermally conductive molded body 20 is located between the metal cover plate 15b and the bracket 11. Therefore, since the thermally conductive molded body 20 has elastic force, it can reduce the stress generated by vibration, and can obtain high reliability. Further, by using the heat conductive molded body 20, the heat generated by the brush 15a, which is a heating element, can be efficiently radiated, so that a highly reliable flat brushless coreless motor can be realized.

As described above, in the flat type brushless coreless motor according to the present embodiment, it is preferable that the heat conductive molded body be silicone rubber or acrylic rubber.

Thereby, high reliability and heat dissipation can be ensured even when the flat type brushless coreless motor is used in a high temperature environment.

The present invention is not limited to the flat type brushless coreless motor and the one shown in the drawings in the above embodiment. For example, the present invention can be implemented by variously changing the design without departing from the gist of the present invention.

As described above, the flat brushless coreless motor according to the present invention can have a long life. Therefore, the present invention can be applied not only to in-vehicle use but also to industrial use or home electric appliance use. In particular, it is useful in the field used under a high temperature environment.

DESCRIPTION OF SYMBOLS 10 Housing 11, 111 Bracket 12 Magnet 13a, 13b Bearing 14, 114 Armature 14a Shaft 14b Commutator 14c Coil 14d Mold resin 15 Brush holder 15a, 115a Brush 15b Cover plate 15c Spring 15d Groove 20 Thermal conductive body 30 Thermal insulation 100 , 101 motor (flat type brushless coreless motor)

Claims (3)

A shaft extending in the axial direction, a plurality of coils attached in a circumferential direction around the axis, and a commutator having a commutator piece connected to each of the plurality of coils are integrally formed by molding resin. A molded armature,
A magnet facing the armature,
A housing for holding the magnet;
The magnet is a bracket positioned facing each other across the armature and a gap,
A brush in contact with the commutator;
A brush holder including a groove in which the brush is movable,
A cover plate that covers the groove,
A thermally conductive molded body located between the bracket and the cover plate,
A flat brushless coreless motor, comprising: a heat insulator having a lower thermal conductivity than air, located between the armature and the bracket. The flat brushless coreless motor according to claim 1, wherein the heat insulating material is impregnated with a heat insulating material containing silica xerogel. 3. The flat brushless coreless motor according to claim 1, wherein the heat conductive molding is made of silicone rubber or acrylic rubber. 4.

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