JP2723459B2 - Small motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to audio equipment, video equipment,
The present invention relates to small motors used in precision equipment, electrical equipment, industrial equipment, etc., and more particularly to small motors capable of improving the vibration damping characteristics of the brush arm for power supply and stabilizing the contact with the commutator. It is.

[0002]

2. Description of the Related Art FIG. 1 is a longitudinal sectional front view of an essential part showing an example of a small motor to which the present invention is applied, and FIG.
FIG. 4 is a cross-sectional view taken along a line A. 1 and 2, reference numeral 1 denotes a case, which is formed of a metal material such as soft iron into a bottomed hollow cylindrical shape, and has a permanent magnet 2 formed, for example, in an arc segment shape fixed to the inner peripheral surface. The case 1 is configured so that a rotor 5 including an armature 3 and a commutator 4 facing the permanent magnet 2 can be interposed.

[0003] Next, reference numeral 6 denotes a case cap, which is formed of, for example, a synthetic resin or another insulating material so as to fit into the opening of the case 1. 7 is a brush arm,
The brush arm 7 is provided on the case cap 6 together with the input terminal 8 which is provided so as to be slidably engaged with the commutator 4. Bearings 9 and 10 are fixed to the bottom of the case 1 and the center of the case cap 6, respectively.
The shaft 11 constituting the rotor 5 is rotatably supported. 13
Is a thrust washer, and 14 is a positioning bush.
Reference numeral 15 denotes a damper material, which is applied to the base of the brush arm 7 and its vicinity.

With the above configuration, current is supplied to the armature 3 from the input terminal 8 via the commutator 4 constituting the rotor 5 via the brush arm 7, thereby fixing the current to the inner peripheral surface of the case 1. The rotating force is applied to the armature 3 existing in the magnetic field formed by the permanent magnet 2
Can be rotated, and an external device (not shown) can be driven via the output-side shaft 11.

In this case, the rotation of the rotor 5 causes the brush arm 7 slidably engaged with the commutator 4 to vibrate, but the base of the brush arm 7 and its vicinity are coated with a damper material 15 made of an adhesive material. As a result, the vibration of the brush arm 7 is attenuated, the current waveform is maintained in a good state, and the mechanical noise can be reduced.

As the adhesive material constituting the damper material 15, a rubber-based, silicone-based, acrylic-based material or the like has been conventionally used (for example, Japanese Patent Application Laid-Open No. Hei 2-26259).
Nos. 5-190015, 2-223356 and 52-149204.

[0007]

However, when a rubber-based adhesive material is used, so-called "sagging" occurs in a high-temperature environment due to low heat resistance, and the state of application to the brush arm 7 changes. Therefore, there is a problem that the vibration damping characteristics vary. Further, since a vulcanized product is used as the rubber-based adhesive material, there is a problem that the sulfur content is adsorbed on the contact point between the brush 7a and the commutator 4, increasing the contact resistance and adversely affecting the motor performance. .

In addition, the silicon-based adhesive material has a problem in that low-molecular siloxane evaporates and is adsorbed on the above-mentioned contacts and combines with oxygen to form an insulating film, thereby causing an undesirable situation of motor stop. There is.

For these reasons, an acrylic adhesive material is used. As this acrylic adhesive material, because of its good workability, general organic solvents,
For example, ethyl acetate, toluene, etc. are used in combination, but there are problems such as the dissolution of other components by the organic solvent, deterioration of motor characteristics due to generation of black powder and brown powder, and contamination of the working environment. .

The present invention solves the above-mentioned problems in the prior art, improves the vibration damping characteristics of the brush arm for power supply, reduces the production cost, and provides a small-sized motor that is inexpensive and has excellent characteristics. With the goal.

[0011]

In order to achieve the above object, in the present invention, there is provided a case formed of a metal material into a hollow cylindrical shape having a bottom and having a permanent magnet fixed to an inner peripheral surface thereof; A rotor composed of an armature and a commutator facing the magnet, a brush arm having a brush fitted into the opening of the case and slidably engaged with the commutator, and electrically connected to the brush arm; A small motor comprising a case cap provided with an input terminal and a rotor rotatably supported via a bearing provided on the bottom of the case and the case cap. Styrene monomer as a main component, 5 to 40% by weight of a styrene monomer is added thereto, and a polymerization reaction is performed.
The technical means of forming a damper material at the base of the brush arm with an adhesive material composed of a water-soluble acrylic emulsion whose initial viscosity was adjusted to 10,000 to 70000 cP was adopted.

In the present invention, if the amount of the styrene monomer is less than 5% by weight, the viscoelasticity is low, that is, it becomes too soft, which is inconvenient. On the other hand, 40
It is not preferable to add more than the weight% because viscoelasticity is lost.

On the other hand, if the initial viscosity of the adhesive material comprising a water-soluble emulsion is less than 10,000 cP, the viscosity becomes insufficient,
It is difficult to maintain the state of application to the base of the brush arm, and it is inconvenient because the brush arm may be washed away. On the other hand, if the initial viscosity exceeds 70,000 cP, it takes a long time to coat the base of the brush arm, and the workability is undesirably reduced.

[0014]

According to the above configuration, the damper material can be stably applied to and held on the base of the brush arm and the case cap near the brush arm, and the vibration damping characteristics of the brush arm can be improved.

[0015]

EXAMPLE A butadiene acrylate monomer was used as a main component, and a styrene monomer was added thereto in the ratio shown in Table 1 to cause a polymerization reaction.
The results of measuring the vibration decay time and the mechanical noise of a small motor which is obtained by applying an adhesive material made of a water-soluble acrylic emulsion adjusted to 00 cP to the base of the brush arm 7 shown in FIG. .

The vibration damping time was determined by a value when the free end of the brush arm 7 was flipped with a constant force in the state shown in FIG. The mechanical noise was measured according to JIS-A characteristics by placing the completed small motor on a sponge having a thickness of 10 cm and using a microphone placed 10 cm apart.

[0017]

[Table 1]

As is evident from Table 1, No. 1 in which no styrene monomer is blended has no damper effect, has a long vibration damping time, and has large mechanical noise. On the other hand, in No. 7, the amount of the styrene monomer was too large, so that the viscoelasticity disappeared and no damper effect was observed. On the other hand, in Nos. 2 to 6, damping effects equivalent to those of conventional rubber-based and silicon-based ones were observed without any pollution and no influence on other components.

Next, with respect to No. 4 shown in Table 1 (containing 20% by weight of styrene monomer), the initial viscosity was changed to form a damper material, and the results of an impact test and a drop test are shown in Table 2.

In the shock test, an operation time of 6 ms was applied to a small motor.
Acceleration 100G, acceleration direction up / down, front / back, left / right impact 1
000 times, and disassembled to remove the damper material 15 (FIG. 2).
(See Reference). The drop test was performed by dropping naturally from the height of 15 cm to the ground in the state shown in Fig. 2.
The state of the damper material 15 was observed.

[0021]

[Table 2]

As apparent from Table 2, No. 8 and N
In the case of o. 9, the scattering of the damper material 15 is recognized because the initial viscosity of the adhesive material composed of the water-soluble acrylic emulsion is low. In contrast, No. 10 to No. 14
Has a stable coating state, and no scattering of the damper material 15 is observed. However, the workability of No. 14 is very poor because the initial viscosity is high, and it takes time to form the damper material 15.

FIGS. 3 (a), 3 (b) and 3 (c) show current waveforms of a small motor having a damper material applied thereon.
No. 8, No. 9 and No. 10 in Table 2 respectively formed the damper material. As shown in (a) and (b) in FIG. 3, since the initial viscosity of the adhesive material composed of the water-soluble acrylic emulsion is low at 5000 cP and 7500 cP, it is difficult to maintain the initial applied state. It can be seen that a stable contact state was not obtained between the commutator and the brush, and the current waveform was unstable. On the other hand, in the case of (c), the initial viscosity of the adhesive material is 10,000 cP, a good initial coating state is secured, the contact state between the commutator and the brush is stable, and a good current waveform is obtained. Have been obtained.

From the results shown in Tables 1 and 2, when a damper material is formed from an adhesive material consisting of a water-soluble emulsion obtained by mixing butadiene acrylate monomer as a main component, a styrene monomer and a polymerization reaction, a styrene monomer is used. It can be seen that the same damper effect as the conventional one can be obtained by blending 5 to 40% by weight and adjusting the initial viscosity to 10,000 to 70000 cP.

[0025]

As described above, the present invention has the above-described structure and operation. Therefore, since the damper material can be applied in a stable state, the vibration damping characteristics of the brush arm are improved, the mechanical noise is reduced, and the motor life is shortened. In addition to the improvement in power and suppression of the brush jump phenomenon, it is possible to prevent rotation fluctuations and stabilize the current waveform. Further, contamination of the contact portion between the commutator and the brush and corrosion of other components can be completely avoided. Further, since automation becomes possible, there is an effect that production cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a main part showing an example of a small motor to which the present invention is applied.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a diagram showing a current waveform of a small motor on which a damper material is applied.

[Explanation of symbols]

 7 Brush arm 15 Damper material

Claims (1)

(57) [Claims] 1. A case (1) formed of a metal material in a hollow cylindrical shape with a bottom and having a permanent magnet (2) fixed to an inner peripheral surface thereof, and an armature (3) facing the permanent magnet (2). )
And a commutator (4), and a brush arm (7) having a brush (7a) fitted into the opening of the case (1) and slidably engaged with the commutator (4). (7)
And a case cap (6) provided with an input terminal (8) electrically connected to the brush arm (7). The case cap (6) is provided at the bottom of the case (1) and the case cap (6). A small motor having the rotor (5) rotatably supported via the provided bearings (9) and (10), comprising a butadiene acrylate monomer as a main component and a styrene monomer in an amount of 5 to 40% by weight. To make a polymerization reaction, and the initial viscosity is 10,000 to 70000 cP
The base material of the brush arm (7) is made of a damper material (1
5) A small motor characterized by forming 5).