JP2005130618A - Electric apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the conductivity at an electric contact point favorably, with simple configuration. <P>SOLUTION: This electric apparatus is constituted so that good lubricating action may be kept for a long period even under high-temperature environment, while having good lubricating action in the whole range of a temperature at which it is used, especially under the low-temperature range, by mounting a lubricant retainer 21 consisting of porous material inside a case 11 having a built-in electric driving mechanism having electric contacts 18, 19, and impregnating the lubricant retainer 21 consisting of the porous material with a gas-phase lubricant of low boiling point which evaporates at an ambient air temperature at the lower limit of the temperature range wherein the electric driving mechanism is used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrical device in which an electrical drive mechanism having electrical contacts is built in a case body.

  In general, an electric drive mechanism having an electric contact is widely used in many electric devices. For example, in a rectifying mechanism of a DC motor with a brush, as shown in FIG. 5, a commutator 2 in which a pair of conductive brush members 1 and 1 made of a conductive metal plate are formed in a substantially cylindrical shape. Are arranged so as to sandwich the outer peripheral surface from both sides in the diameter direction. A current-carrying contact portion 1 a is provided at the tip of each of the pair of conductive brush members 1, 1, and each of the current-carrying contact portions 1 a, 1 a,. By sliding in such a state, electrical contacts are formed at these sliding portions.

  By the way, the electrical contact between the conductive brush member 1 and the commutator 2 having such a configuration is always maintained in a stable electrical contact state in order to drive the motor at a low voltage without unevenness. Indispensable, in order to realize this, alloys of noble metals (Au, Pd, Pt, Ag, etc.) and alloys obtained by adding Cu, Ni, Zn, etc. to them are adopted for the electrical contacts. Many.

  However, when a brushed DC motor is actually produced and used, a wide variety of organic gases generated from adhesives, lubricants, resin parts, etc. exist in the atmosphere inside and outside the motor case body. These various organic gases are burned by arc discharge, frictional heat, or Joule heat of current generated during rectification operation, and electrically insulative black foreign substances called “powder” are often generated on the commutator 2 as the burning residue. Generated. If the powder is in a state of being interposed between the electrical contacts of the brush member 1 and the commutator 2, the current supply between the electrical contacts becomes unstable, causing a conduction failure, and starting failure or electric Noise will be generated. Further, it is widely known that when siloxane (silicone) is contained in an organic gas that causes such conduction failure, a serious conduction failure occurs in an extremely short time.

  On the other hand, the conductive brush member 1 and the commutator 2 described above are formed of a metal member. That is, in the DC motor with a brush, since a configuration in which the metal members slide directly is adopted, in general, the wear of the conductive brush member 1 is significantly advanced in an environment with little water vapor such as low humidity and low temperature. However, there arises a problem that a predetermined life cannot be obtained.

  As countermeasures against such contact problems due to organic gas and life problems due to wear, proposals have conventionally been made to use a vapor phase lubricant made of polyhydric alcohol or the like to make the inside of the case body a vapor atmosphere ( See the following Patent Documents 1, 2, and 3. In the proposal, in addition to the structure in which the gas phase lubricant is applied to the inside of the case body, in order to keep the gas phase lubricant in the case body for as long as possible, a felt material, a field magnet, Alternatively, a magnet wire or the like is impregnated with a gas phase lubricant, or a plastic component is blended with a gas phase lubricant. However, in any of these structures, it is difficult to hold a large amount of the gas phase lubricant in a limited space inside the case body, and a low boiling point gas phase that exhibits its effect even in a low temperature environment. Since the lubricant is evaporated more rapidly than necessary under a high temperature environment, there is a problem that the remaining time (effect duration) is insufficient with respect to the required motor life, and as a result, it is difficult to obtain a sufficient effect.

  Accordingly, a structure in which a gas-permeable film-like member enclosing a gas-phase lubricant is attached to the inside of the case body to suppress the evaporation rate of the gas-phase lubricant has been proposed (the following patent document) 4), since the gas-permeable film-like member becomes a relatively large component, it is difficult to employ it in an electric device that is particularly downsized. There is also a problem that it must be expensive.

  Furthermore, a low boiling point gas phase lubricant that has a good lubricating function or wear suppression action in the low temperature range of the temperature range to be used is used, and a high boiling point is used to suppress the evaporation rate in the low boiling point gas phase lubricant. A construction in which a gas phase lubricant is blended is also known (see Patent Document 5 below). However, in this case, the low boiling point gas phase lubricant tends to be insufficient due to the blended structure, so that it is difficult to obtain a steam atmosphere in a low temperature environment despite the low boiling point, and wear control is suppressed. The effect may not be obtained sufficiently.

  Thus, a proposal has been made to use a gas phase lubricant having a large molecular weight with a low evaporation rate (see Patent Document 6 below), but a gas phase lubricant having a large molecular weight tends to have a high boiling point and melting point. For this reason, of course, the evaporation does not easily occur in a low temperature environment, and the lubricating action is not sufficient.

Japanese Patent No. 1593391 Patent No. 1910433 Patent No. 1949039 Patent No. 2033903 Japanese Patent No. 2875428 Japanese Patent No. 3240552

  Accordingly, an object of the present invention is to provide an electrical device that has a simple configuration and can maintain good electrical conductivity and wear resistance between electrical contacts over a long period of time in the entire temperature range to be used. And

In order to achieve the above object, in the electrical device according to claim 1 of the present invention, a lubricant holder made of a porous material is disposed inside a case body having an electric drive mechanism having an electrical contact. The porous material of the lubricant holder is impregnated with a low-boiling vapor phase lubricant that evaporates at an ambient temperature that is the lower limit of the temperature range in which the electric drive mechanism is used.
For example, in the electrical device according to claim 2 of the present invention, an alcohol-based chemical is used as the low boiling point gas phase lubricant in the above claim 1, and in the electrical device according to claim 3 of the present invention, Activated carbon is used as the porous member in claim 1.

According to each of the electric devices according to claim 1, claim 2 and claim 3 having such a configuration, the low boiling point gas phase lubricant held in the lubricant holder made of the porous material is a low temperature environment. Since it has a smooth evaporating action even underneath, a good lubricating action can be obtained even in a low temperature environment.
In addition, the vaporizing action of the low-boiling gas phase lubricant is performed slowly through the pores (pores) of the porous material constituting the lubricant holder, and is controlled at an appropriate evaporation rate. Even in the environment, the above-described good lubricating action of the gas phase lubricant is maintained over a long period of time.

In the electric device according to claim 4 of the present invention, the electric drive mechanism according to claim 1 is a rectifying mechanism in a DC motor with a brush, and an electrical contact is formed at a sliding portion of the brush and the commutator in the rectifying mechanism. Has been.
The present invention can maintain particularly good continuity and wear resistance over a long period of time in such a rectifying mechanism of a brushed DC motor.

  As described above, in the electrical device according to the present invention, the lubricant holding body made of a porous material is attached to the inside of the case body incorporating the electric drive mechanism having the electrical contacts, and the lubricant holding made of the porous material is held. The body is impregnated with a low-boiling gas phase lubricant that evaporates at the lower ambient temperature of the temperature range using the electric drive mechanism. It is designed to maintain its good lubricating action over a long period of time even in a high temperature environment, so it can improve electrical conductivity at the electrical contacts and improve wear resistance with a simple configuration. The reliability of electrical equipment can be greatly increased at low cost.

  Hereinafter, embodiments in which the present invention is applied to a brushed DC motor will be described in detail with reference to the drawings.

  First, the overall structure of the brushed DC motor shown in FIG. 1 will be described. Inside the motor case 11 formed so as to form a hollow cylinder, there is a rotating shaft along the central axis of the motor case 11. 12 is arranged. The rotary shaft 12 is rotatably supported by a pair of metal bearings 13 and 14 fixed to both end portions in the axial direction of the motor case 11, and an electromagnetic steel plate is provided at a substantially central portion in the axial direction of the rotary shaft 12. A rotor core (an amateur core) 15 made of a laminated body such as the above is fixed so as to be inserted therethrough, and a rotor coil 16 is wound around and mounted on salient poles extending radially of the rotor core 15.

  A stator magnet (field magnet) 17 that is annularly attached to the inner peripheral wall surface of the motor case body 11 is annularly arranged on the outer peripheral side of the rotor core 15. The salient poles of the rotor core 15 described above are arranged so as to oppose each other in the radial direction with respect to the peripheral wall surface.

  Further, a commutator 18 is attached to one end side (the lower side in FIG. 1) of the rotary shaft 12 so as to form a substantially cylindrical shape so as to rotate integrally with the outer peripheral surface of the commutator 18. Thus, a pair of conductive brush members 19 made of a conductive metal plate are arranged so as to sandwich the outer peripheral surface of the commutator 18 in the diameter direction. The conductive brush members 19 and 19 and the commutator 18 constitute a rectifying mechanism having an electrical contact that slides relatively in a brushed DC motor, that is, an electric drive mechanism. The configuration is the same as that described in the section of the prior art and in FIG. 5 and will not be described here.

  Inside the motor case body 11 described above, lubricant holders 21 and 21 made of a porous material are mounted at two locations on both sides of the rotor core 15 described above. Each of these lubricant holders 21 is attached to both end surfaces of the motor case body 11 in the axial direction by various fixing means such as double-sided tape. As the porous material constituting the lubricant holder 21 according to the present embodiment, fibrous or granular activated carbon is adopted, but powdered activated carbon may be molded with a binder. Other porous materials such as zeolite and molecular sieves can also be employed.

  And the porous material which comprises such a lubricant holding body 21 is impregnated with the low boiling point gas phase lubricant. As the low boiling point gas phase lubricant, one that evaporates at the lower ambient temperature of the temperature range in which the motor is used is used. Here, the lower limit of the temperature range in which the motor is used means, for example, the lower limit of the outside air temperature assumed when the motor is actually used, and specifically, −20 ° C. is usually the lower limit at that time. Become. Further, depending on the use environment of the motor, −30 ° C. may be the lower limit of the temperature range. Further, in the present embodiment, various alcohol-based chemicals such as ethylene glycol and trimethylene glycol are employed as the above-described low-boiling gas phase lubricant.

  According to such a DC motor with a brush according to this embodiment, the low-boiling vapor phase lubricant held by the lubricant holder 21 made of a porous material has a smooth evaporation action in a low-temperature environment. However, it does not disappear in a short time even in a high temperature environment, and a good lubricating action can be obtained over a long period in the entire temperature range in which the motor is used.

  Further, the vaporizing action of the low-boiling vapor phase lubricant at that time is gradually performed through the pores of the porous material constituting the lubricant holding body 21. That is, the activated carbon used for the porous material constituting the lubricant holder 21 in the present embodiment is a carbon material having a large number of fine pores of 10 to 200 mm and a very large surface area per unit weight, Generally, it is used as a gas adsorbing material. On the other hand, in the above-described embodiment according to the present invention, activated carbon (porous material) is used as a member for holding a low boiling point gas phase lubricant, not as a gas adsorbing material.

  In other words, the vapor of the low-boiling gas phase lubricant enters the micropores of the activated carbon (porous material) and is held inside for a long time. The vaporization rate of the low-boiling vapor phase lubricant can be remarkably reduced as compared with those obtained by impregnating ordinary fibers such as felt and felt. On the other hand, since the vapor phase lubricant itself has an appropriate vapor pressure even at a low temperature, the vapor phase lubricant evaporates little by little through the fine pores of the porous material. It is suppressed by the evaporation rate. Therefore, as described above, a good and stable lubricating action by the gas phase lubricant is maintained over a long period of time.

  For example, ethylene glycol in the above-described low boiling alcohol-based gas phase lubricant has a boiling point of 196 ° C. and a melting point of −18 ° C., and trimethylene glycol has a boiling point of 214 ° C. and a melting point of −32 ° C. In the case where a single solution of each gas phase lubricant is held in a container (15 μL) and left as it is (40 ° C., 20% RH), it is indicated by broken lines “A” and “O” in FIG. As it is done, it decreases in a short time due to rapid evaporation. Further, when the felt is impregnated with ethylene glycol and left in the same manner, as shown by the one-dot chain line “Ak” in FIG.

  On the other hand, when the vapor phase lubricants of ethylene glycol and trimethylene glycol are impregnated in the lubricant holder 21 made of activated carbon as in the above-described embodiment, the solid lines in FIG. As indicated by “A-j” and “O-j”, respectively, it was confirmed that the decrease rate of each of these gas phase lubricants was greatly relaxed.

  In addition, FIG. 3 shows the result of a life test performed by mounting each gas phase lubricant on an actual brushed DC motor. In the life test at this time, a disk drive device having a DC motor with a brush having an outer diameter of 24 mm and a height of 12 mm was used. It was decided to repeat the operation to intermittently rotate the rotation mode that combined constant speed, brake, and pause. Then, each time was measured until the current stopped flowing through the electrical contact between the conductive brush member and the commutator and the rotation stopped.

  As a result, as shown in FIG. 3, a single vapor-phase lubricant was applied to the motor case body for the life time (reference numerals 01 and 02) when no vapor-phase lubricant was used. In this case, the life time (reference numerals 11 and 12) was slightly extended and slightly improved. On the other hand, when the lubricant holder 21 made of activated carbon is impregnated with the gas phase lubricant as in the embodiment of the present invention described above, the life time of the motor (reference numerals 21 and 22) is greatly increased. It was found to be extended.

  Although the embodiments of the invention made by the present inventor have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. Not too long.

  For example, in the embodiment described above, the lubricant holder 21 is fixed to the inner wall surface of the motor case body, but it is naturally possible to attach the lubricant holder 21 to other parts.

  Moreover, although embodiment mentioned above applies this invention with respect to the DC motor with a brush, this invention is the same with respect to the electric equipment which has various electrical contacts, such as a switch, a relay, a connector. Can be applied to.

  The present invention described above can be widely applied to a wide variety of electric devices including brushed DC motors.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional explanatory view showing the overall structure of a brushed DC motor in an embodiment of the present invention. It is a diagram showing the result of having measured the time required for weight reduction when a gas phase lubricant is left in various modes. It is the diagram showing the result at the time of performing a life test, mounting a gaseous-phase lubricant on a direct-current motor with a brush. It is the diagram showing an example of the operation mode in the lifetime test of the direct-current motor with a brush in FIG. It is an external appearance perspective explanatory view showing an example of structure of a brush device in a general DC motor with a brush.

Explanation of symbols

11 Motor case 12 Rotating shaft 15 Rotor core 18 Commutator (electrical contact)
19 Brush members (electrical contacts)
21 Lubricant holder

Claims (4)

In an electrical device in which an electrical drive mechanism having electrical contacts is built in the case body,
A lubricant holder made of a porous material is disposed inside the case body,
An electrical apparatus, wherein the porous material of the lubricant holder is impregnated with a low-boiling vapor phase lubricant that evaporates at an ambient temperature that is a lower limit of a temperature range in which the electric drive mechanism is used. 2. The electrical apparatus according to claim 1, wherein an alcohol-based chemical is used as the low boiling point gas phase lubricant. The electrical device according to claim 1, wherein the porous member is made of activated carbon. The electric drive mechanism is a rectifying mechanism in a brushed DC motor,
The electrical device according to claim 1, wherein the electrical contact is formed at a sliding portion between a brush and a commutator constituting the rectifying mechanism.

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