JPH0538088A - Dc miniature motor - Google Patents

Abstract

PURPOSE:To provide a DC miniature motor which exhibits its functions stably for a long term and in which oxidation of composition members and intrusion of harmful gas into the inner space are prevented. CONSTITUTION:In the DC miniature motor comprising a casing 1 secured with a permanent magnet on the inner peripheral face thereof, a rotor having an armature and a commutator, a casing cap 6 having a brush and an input terminal, and a rotor supported by bearings mounted in the casing 1 and the casing cap 6, a shaft sealing means 14 incorporating magnetic fluid is provided at the end of the casing on the output shaft side of the rotor so that the inner space 13 defined by the casing 1 and the casing cap 6 is enclosed against the outer air and then a function member 19 having deoxydizing function is placed in the inner space 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small direct current motor used in, for example, audio equipment, precision equipment, etc., and in particular, the internal space of the motor is formed into a closed structure which is isolated from the outside air, The present invention relates to a small DC motor improved so as to prevent functional deterioration of motor constituent members due to contained oxygen and other substances.

[0002]

2. Description of the Related Art FIG. 3 is a vertical sectional front view of an essential part showing an example of a conventional small DC motor. In FIG. 3, reference numeral 1 denotes a case, which is formed of a metal material such as soft iron into a hollow cylindrical shape with a bottom, and has an inner peripheral surface to which a permanent magnet 2 formed in, for example, an arc segment shape is fixed. A rotor 5 including an armature 3 facing the permanent magnet 2 and a commutator 4 can be provided in the case 1. Next, 6 is a case cap, which is formed of, for example, a synthetic resin or other insulating material so that it can be fitted into the opening of the case 1. 7
Is a brush arm, which is provided so as to be slidably engaged with the commutator 4, and is provided on the case cap 6 together with the input terminal 8 electrically connected to the brush arm 7. 9, 1
Reference numeral 0 denotes a bearing, which is fixed to the bottom portion of the case 1 and the central portion of the case cap 6, and which constitutes the rotor 5 and has shafts 11 and 1 respectively.
2 is rotatably supported.

With the above configuration, the current is supplied to the armature 3 from the input terminal 8 via the brush arm 7 and the commutator 4 constituting the rotor 5, so that the case 1 is fixed 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 generated permanent magnets 2,
Can be rotated, and an external device (not shown) can be driven via the output side shaft 11.

[0004]

In the conventional small direct current motor having the above-mentioned structure, the atmosphere of the internal space 13 formed by the case 1 and the case cap 6 is the same as the bearing 9
Since it has air permeability through, it is generally the same as the outside air atmosphere and cannot be completely shut off. Therefore, there is a problem that the constituent members are oxidized by spark discharge and Joule heat between the brush (not shown) at the tip of the brush arm 7 and the commutator 4. When such a component is oxidized, the contact resistance at the sliding contact portion is increased, the damage due to the spark discharge is further accelerated, the wear of the brush and the commutator is promoted, and the life is remarkably shortened. Becomes

Further, the above-mentioned conventional small direct current motor has a shaft 1
Sintered oil-impregnated bearings as bearings 9 and 10 for supporting 1 and 12,
It is common to use ball bearings and the like. Therefore, the case cap 6 side can be sealed, but the output side cannot completely seal the bearing 9 or the gap between the shaft 11 and the bearing 9. Therefore, when the volume of the internal space 13 changes due to the temperature change, the air flows inside and outside the motor through the bearing 9 or the gap between the shaft 11 and the bearing 9.

In the above-mentioned air-permeable structure, the internal space 13 cannot be maintained cleanly, and especially when used in an environment containing corrosive gas and organic gas, these The harmful gas will enter the internal space 13 of the motor from the outside. These harmful gases cause a chemical reaction with the constituent members in the internal space 13 due to the spark discharge and heat generation, and generate a blackening substance mixed with the sliding wear powder. Since this blackening substance generally has an insulating property, it has an undesired effect of making the contact state between the commutator 4 and the brush unstable and increasing the contact resistance. As described above, in the conventional small DC motor, corrosive gas and organic gas intrude into the internal space 13 of the motor from the outside, deteriorating the functions of the electric sliding contacts and other components, and significantly reducing the function of the motor. There is a problem of causing it.

The present invention solves the problems existing in the above-mentioned prior art, prevents the constituent members from oxidizing, and prevents the harmful gas from entering the internal space, and exhibits a stable function for a long period of time. An object is to provide a small DC motor to be obtained.

[0008]

In order to achieve the above object, first of all, in the first aspect of the invention, there is provided a case formed of a metallic material in the shape of a hollow cylinder having a bottom and a permanent magnet fixed to the inner peripheral surface. A rotor having an armature facing the permanent magnet and a commutator, a brush fitted in the opening of the case and slidably engaged with the commutator, and electrically connected to the brush. In a small direct current motor comprising a case cap provided with an input terminal, the rotor is rotatably supported through a bearing provided on the bottom of the case and the case cap, By providing a shaft sealing means containing a magnetic fluid at the end of the case on the shaft side, the internal space formed by the case and the case cap has a closed structure that is shielded from the outside air, and the internal space has a deoxidizing function. Providing the ability member, employing the technical means of.

Next, in the second aspect of the invention, a case formed of a metallic material in the shape of a hollow cylinder with a bottom and having a permanent magnet fixed to the inner peripheral surface thereof, an armature facing the permanent magnet, and a commutator. And a case cap provided with a brush fitted in the opening of the case and slidably engaged with the commutator, and an input terminal electrically connected to the brush. In a small DC motor in which the rotor is rotatably supported via bearings provided on the bottom of the case and a case cap, a shaft containing magnetic fluid at the case end on the output shaft side of the rotor By providing a sealing means, the internal space formed by the case and the case cap has a sealed structure that is shielded from the outside air, and the internal space is formed into an inert gas atmosphere, which is a technical means.

Further, in the third invention, the technical means of providing a functional member having a humidity control function in the internal space is added to the technical means of the second invention.

[0011]

With the above structure, the internal space of the motor is completely cut off from the outside air, the outside air can be completely prevented from entering the inside space, and the functional deterioration of the constituent members due to harmful gas can be prevented. By providing a functional member having a deoxidizing function in the internal space or forming the internal space in an inert gas atmosphere, it is possible to eliminate the oxidizing effect in the internal space and further prevent the functional deterioration of the constituent members. Be encouraged. Further, by providing a functional member having a humidity control function in the internal space, the internal space can be maintained at the optimum humidity, and the adsorption of the monomolecular film of water can promote the lubricating action between the sliding members.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a vertical sectional front view of a main part showing a first embodiment of the present invention. The same parts are designated by the same reference numerals as those in FIG. In FIG. 1, the case 1 has a large diameter portion 1a and a small diameter portion 1b.
The shaft 9 on the output side is rotatably supported by providing the bearing 9 on the small diameter portion 1b. Next 14
Is a shaft sealing means, which is formed so as to seal the flow of gas by containing a magnetic fluid, and is provided near the outer end of the small diameter portion 1b. That is, the shaft sealing means 14 is formed in a hollow cylindrical shape and is magnetized in the thickness direction, and the permanent magnet 1 formed in a hollow cylindrical shape by a magnetic material such as soft iron.
The yoke 16 is fixed to both end surfaces of the magnetic disk 5, and the magnetic fluid 17 is interposed in the ring-shaped space formed by the yoke 16 and the shaft 11.

The shaft sealing means 14 is fitted to the inner peripheral surface of the small diameter portion 1b and is coated with an adhesive 18 to form an airtight holding structure. Also, the large diameter portion 1a of the case 1
The adhesive 18 is also applied to the joint between the open end of the case and the case cap 6 and the vicinity of the protruding portion of the input terminal 8 to form an internal space 13 formed by the case 1 and the case cap 6.
Formed in an airtight closed state that is shielded from the outside air. Next 19
Is a functional member, for example, is formed in a hollow cylindrical shape and is provided in the internal space 13. The functional member 19 is formed, for example, by enclosing pure iron powder in a filter or paper having air permeability, or by mixing it with resin or the like to form, for example, a ring shape.
Adhesive is used on the part in 3 where the motor function is not hindered, or it is fixed by pressure bonding or other means.

With the above structure, oxygen in the air in the internal space 13 is absorbed by the functional member 19, that is, 4Fe +
The reaction of 3O ₂ → 2Fe ₂ O ₃ can bring the oxygen concentration to a greatly reduced state or the anoxic state. Therefore, it is possible to prevent oxidation of the constituent members due to spark discharge and / or Joule heat between the brush (not shown) and the commutator 4 that compose the small DC motor.

Table 1 shows the results of the life test, and was conducted on a small DC motor manufactured according to the same specifications.

[0016]

[Table 1]

As is clear from Table 1, No. 1 to No. 5
In the conventional small DC motor, the average life is limited to 134 hours as a result of the presence of air inside the motor and the progress of oxidation of the constituent members. On the other hand, as shown in FIG. 1, it can be seen that in Nos. 6 to 10 of the present invention in which the functional member 19 having a deoxidizing function is provided in the internal space 13, the average life is increased to 361 hours. . This is the internal space 1
It is considered that this is due to the fact that the oxidation of the motor constituent members is prevented as a result of the significant decrease in the oxygen concentration in 3.
In Table 1, "stop" means stop of the motor rotating shaft due to wear of constituent members, and "stop" means that the test was stopped while the rotation of the motor rotating shaft was in a normal state.

In this embodiment, an example in which the functional member 19 is made of pure iron powder has been described, but the functional member 19 is not limited to pure iron powder, but Al, B, C, Cr, Mn, Si, Ti,
Those composed of other elements such as V and Zr, their compounds, or a mixture of two or more of these may be used, in short, it may be composed of a substance having a large affinity with oxygen in the air. . Further, the shape of the functional member 19 can be set in the internal space 13 and can be appropriately selected as long as it does not hinder the motor function.

FIG. 2 is a vertical sectional front view of a main part of a second embodiment of the present invention, and the same parts are designated by the same reference numerals as those in FIG. In this embodiment, the functional member is removed from the structure shown in FIG. Then, the internal air in the internal space 13 shown in FIG. 2 was replaced with high-purity (99.9% or more) nitrogen gas and carbon dioxide gas. Table 2 shows the results of a life test performed on the small DC motor configured as described above. The results for the conventional small DC motor of the same specifications shown in FIG. 3 are also shown. Further, “stop” in Table 2 means stop of the motor rotating shaft due to wear of the constituent members.

[0020]

[Table 2]

As is clear from Table 2, No. 1 to No. 4
In the conventional small DC motor, the average life is 290 hours as a result of the presence of air inside the motor and the progress of oxidation of the constituent members. On the other hand, the air in the internal space 13 shown in FIG. 2 was replaced with nitrogen gas or carbon dioxide gas to form an inert gas atmosphere.
It can be seen that in No. 12, the average life is increased 3 to 5 times as compared with the conventional one. This is considered to be the result of preventing the oxidation of the motor constituent members due to the formation of the internal space 13 in the inert atmosphere. In addition to the above, helium gas, argon gas or the like may be used as the inert gas.

Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 1, the functional member 19 is formed of a material having a humidity control function, such as silica gel, zeolite, or cotton. That is, these materials are enclosed in a filter or paper having air permeability, or mixed with resin or the like to form, for example, a ring shape, and an adhesive is used in a portion of the internal space 13 that does not interfere with the motor function. , Or by means of crimping or other means. Then, the internal air in the internal space 13 was replaced with high-purity (99.9% or more) nitrogen gas.

Small DC motor 4 constructed in this way
As a result of the life test for each piece, the test time was 5
It was confirmed that the operation could be continued even after 900 hours. The specifications of the small DC motor of this embodiment are the same as those of the second embodiment. Therefore, it was confirmed that the average life was 10 times or more as compared with the conventional one, and 5 times or more as compared with No. 5 to No. 8 in Table 2 in the second embodiment. It was Since the relative humidity can be maintained at 40 to 80% in the temperature range of 20 to 60 ° C. of the internal space 13 by providing the functional member 19 having the humidity control function in the internal space 13, the second embodiment is described above. In addition to the action in the example, it is presumed that the adsorption of the monolayer of water promotes the lubricating action between the motor components. Similar effects can be expected when the inert gas is replaced with carbon dioxide gas other than nitrogen gas, helium gas, argon gas, or the like. The shape of the functional member 19 is the same as that in the first embodiment, that is, the internal space 1
3 can be installed and can be appropriately selected as long as it does not interfere with the motor function.

[0024]

EFFECTS OF THE INVENTION Since the present invention has the structure and operation as described above, the following effects can be obtained. (1) Since the internal space of the motor has an airtight closed structure that is shielded from the outside air, stable functions can be exhibited for a long period of time even in an environment containing corrosive gas or organic gas. (2) The oxygen concentration in the internal space of the motor can be significantly reduced, or the atmosphere can be made oxygen-free or an inert gas atmosphere, so that it is possible to prevent spark discharge of components and oxidation due to Joule heat, and to reduce the life. Can be greatly increased. (3) By providing a member with a humidity control function in the internal space of the motor, the atmosphere in the internal space can be adjusted to the optimum humidity, and the adsorption of the water monomolecular film causes the sliding action between the sliding members. And the effect of increasing the life can be doubled.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a main part showing a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional front view of essential parts showing a second embodiment of the present invention.

FIG. 3 is a front view of a vertical cross section of an essential part showing an example of a conventional small DC motor.

[Explanation of symbols]

1 case 6 case cap 13 Internal space 14 Shaft sealing means 19 Functional members

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Tsuyama             Mabimo, 430 Matsuhidai, Matsudo City, Chiba Prefecture             Tar Co., Ltd.

Claims (3)

[Claims] 1. A case formed of a metallic material in the shape of a hollow cylinder with a bottom and having a permanent magnet fixed to the inner peripheral surface thereof, and a rotor including an armature facing the permanent magnet and a commutator.
The case includes a brush fitted in the opening of the case and slidably engaged with the commutator, and a case cap provided with an input terminal electrically connected to the brush. In a small direct current motor in which the rotor is rotatably supported through a bearing provided on the case cap, by providing a shaft sealing means containing a magnetic fluid at the case end portion on the output shaft side of the rotor, A small direct current motor characterized in that an internal space formed by a case and a case cap has a closed structure that is shielded from the outside air, and a functional member having a deoxidizing function is provided in the internal space. 2. A case formed of a metallic material in the shape of a hollow cylinder having a bottom and having a permanent magnet fixed to the inner peripheral surface thereof, and a rotor composed of an armature and a commutator facing the permanent magnet.
The case includes a brush fitted in the opening of the case and slidably engaged with the commutator, and a case cap provided with an input terminal electrically connected to the brush. In a small direct current motor in which the rotor is rotatably supported through a bearing provided on the case cap, by providing a shaft sealing means containing a magnetic fluid at the case end portion on the output shaft side of the rotor, A small direct current motor characterized in that the inner space formed by the case and the case cap has a closed structure that is shielded from the outside air, and the inner space is formed in an inert gas atmosphere. 3. The small DC motor according to claim 2, wherein a functional member having a humidity control function is provided in the internal space.