JP2007037374A - Brush motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of trouble, such as the deterioration of the generation rate of an electric signal due to wear, by enhancing service lifetime characteristics of a brush with a simple shape structure. <P>SOLUTION: The carbon brush 15 is formed into an L-shape or a T-shape, and a sliding contact part 16 on the tip side of the carbon brush 15 is brought into elastic contact with the outer peripheral face of a commutator 7. The width dimension W1 of the sliding contact part 16 of the carbon brush 15 is formed smaller than the width dimension W2 of the holder-side fixing end part 17 and slightly larger than the gap dimension W3, between terminals 13 close to each other of the commutator 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brush motor, and more particularly to a novel and useful brush motor that eliminates problems due to brush wear and improves the service life characteristics.

A brush structure in a conventional DC brush motor will be described with reference to FIGS. In the figure, a rotor shaft 2 having an iron core 1 around which a coil is wound is attached to a case 3 via bearings 4 and 5, and a stator side magnet 6 is fixed inside the case 3. Yes. Further, a commutator 7 that is a conduction portion and a carbon brush 8 that is elastically slidably contacted with the commutator 7 are provided on one side of the rotor shaft 2, and the carbon brush 8 is shown in FIG. Further, the carbon brush holder 9 is fixedly held at the tip 10. The carbon brush holder 9 is fixed to the case 3 side via a bracket 11. In addition, 12 is a bracket cover (for example, refer patent document 1).
JP 2000-175212 A

  As shown in FIG. 9, the carbon brush 8 is formed in a rectangular shape as a whole, and has a flat surface on the side in contact with the commutator 7. Further, the proximal end holder fixing end portion and the distal end side contact end portion (sliding contact portion) of the carbon brush 8 have the same width. According to this brush structure, in the initial state when the carbon brush 8 is new, that is, in the state where the flat surface of the tip portion is not worn, the sliding contact portion of the carbon brush 8 and the outer peripheral surface of the commutator 7 are in line with each other. In contact. However, the sliding contact portion of the carbon brush 8 exhibits a concave curved surface following the outer peripheral surface of the commutator 7 as shown in FIG. 10 due to rotational wear with the outer peripheral surface of the commutator 7 with use.

  As a result, the sliding contact portion of the carbon brush 8 changes from the initial line contact to the curved surface contact. Therefore, the carbon brush 8 is generated especially when the contact area between the adjacent commutators 7 crosses between the terminals 13 and 13 in combination with the increase in the contact area of the sliding contact portion and the change in the contact pressure with respect to the terminals 13 and 13. The generation rate of pulsed electric signals is reduced.

  As described above, in the conventional brush structure, the lifespan of the carbon brush 8 is greatly influenced by the friction state between the carbon brush 8 and the commutator 7. It increases as the period of use increases.

  In particular, the tip surface of the carbon brush 8 tends to increase the amount of wear depending on the roughness of the outer peripheral surface of the commutator 7, and when the amount of wear of the carbon brush 8 exceeds a certain value, the commutator on the worn surface. The contact area with respect to 7 becomes wide, and the contact pressure per unit area decreases. Accordingly, since the carbon brush 8 changes from the initial line contact to the surface contact with respect to the commutator 7, an electric signal generated when the carbon brush 8 crosses between the terminals 13, 13, that is, a pulsed signal for coil excitation. There is a problem that the occurrence rate of the brush motor is reduced and the performance of the brush motor is lowered.

  Therefore, there is a technical problem to be solved in order to increase the service life of the brush with a simple shape and prevent a decrease in the generation rate of the electrical signal due to wear, and the present invention solves the problem. Objective.

The present invention has been proposed to achieve the above object, and the invention according to claim 1 is in contact with a commutator having a plurality of terminals and rotating integrally with a rotor shaft, and an outer peripheral surface of the commutator. The brush motor provided with the brush WHEREIN: The width dimension of the sliding contact edge part of the said brush is provided slightly larger than the gap | interval dimension between the terminals of the said commutator.

  According to this configuration, since the width dimension of the sliding contact end portion of the brush is slightly larger than the gap size between the commutator terminals (commutator pieces), the brush sliding contact end portion increases wear due to friction. However, the contact area and the contact pressure are hardly changed, and the contact state equivalent to the line contact in the initial state when new is maintained.

  According to a second aspect of the present invention, there is provided the brush motor according to the first aspect, wherein the sliding contact end portion of the brush is provided at a tip end portion of a portion formed in a band shape.

  According to this configuration, since the sliding contact end portion of the brush is provided at the tip portion narrowed in a band shape, the initial characteristics at the time of a new article are equivalent until the amount of wear increases to the length of the band portion. The contact state is maintained.

  According to a third aspect of the present invention, there is provided the brush motor according to the first aspect, wherein the sliding contact end portion of the brush is provided at a tip end portion of a tapered portion.

  According to this configuration, since the sliding contact end portion of the brush is provided at the tip portion narrowed in a tapered shape, the initial amount of wear is increased until the wear amount increases to the length of the tapered portion. A contact state equivalent to the characteristics is maintained.

  According to a fourth aspect of the present invention, there is provided the brush motor according to the first, second or third aspect, wherein the brush is formed in an L shape, a T shape or a trapezoidal shape.

  According to this configuration, the sliding contact end portion of the brush is formed at the tip of the narrow portion or the narrow portion of the L shape, the T shape, or the trapezoidal shape. In this case, the width of the proximal end side fixing portion of the brush is set to a size larger than a required value, and the width of the sliding contact end portion is set to be slightly larger than the distance between adjacent terminals of the commutator. .

  According to the first aspect of the present invention, the effective rectifying action is maintained for a long period of time by substantially increasing the effective length of the brush. That is, even if the wear amount of the sliding contact end portion increases with use, the contact property equivalent to the initial line contact is maintained, so that the life property of the brush is improved compared to the conventional one, Since the contact area and the contact pressure are hardly changed, an excellent effect of preventing a decrease in the generation rate and size of the excitation electrical signal can be obtained.

  In the invention described in claim 2, since the sliding contact end portion of the brush maintains the contact state equivalent to the initial state until the strip-shaped narrow portion disappears due to wear, in addition to the effect of the invention described in claim 1 Thus, even if the wear amount of the sliding contact end portion is considerably increased, there is a specific merit that a malfunction of the rectifying action such as a decrease in signal characteristics accompanying this can be surely prevented.

  In the invention according to claim 3, since the sliding contact end portion of the brush is kept in the contact state equivalent to the initial state until the tapered narrow width portion disappears due to wear, the amount of brush wear is considerably large as described above. Even if it increases, it is possible to surely prevent a rectifying malfunction such as a decrease in signal characteristics.

In the invention of claim 4, the L-shaped, T-shaped or trapezoidal brush can set the base end side width to a required value or more and can form the tip end side portion narrowly. In addition to the effects of the invention described in, 2 or 3, the brush life can be improved and the fixing strength can be secured at the same time while the brush shape is simple.

  In the best mode of the present invention, the width of the sliding contact end of the brush is smaller than the width of the fixed end of the brush and slightly larger than the gap between the terminals of the commutator. As a result, the service life characteristics of the brush were greatly improved, and the purpose of reliably preventing defects in the generation of electrical signals due to brush wear was achieved.

  The structure is simple by forming the brush in an L-shape, T-shape or trapezoidal shape, and providing a sliding contact end at the tip of the strip-shaped narrow-width portion or the tapered narrow-width portion. However, both the improvement of the brush life and the securing of the brush fixing strength are satisfied, and the signal characteristics equivalent to the initial state are ensured over a long period of use.

  An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory view showing a DC brush motor according to the present embodiment, FIG. 2 is a detailed view showing an L-shaped brush portion, and FIGS. 3 and 4 are a front view and a side view showing the shape of the brush. This embodiment is applied to the same type of DC brush motor as the conventional example described above, and the same members as those shown in FIG. 8 are denoted by the same reference numerals.

  In FIG. 1, reference numeral 2 denotes a rotor shaft having an iron core around which a coil is wound in an intermediate portion. The rotor shaft 2 is rotatably attached to a motor case (not shown) via a bearing 5. A stator-side magnet (not shown) is fixed at a position corresponding to the iron core on the inner surface of the motor case.

  On one side of the rotor shaft 2, a commutator 7 that is a conduction portion and a pair of carbon brushes 15 that elastically contact the outer peripheral surface so as to be sandwiched from both sides are provided. The commutator 7 has three terminals (commutator pieces) 13 on the outer peripheral surface, and rotates integrally with the rotor shaft 2. The carbon brush 15 is fixedly attached to the tip 10 of the pair of carbon brush holders 9, and each carbon brush holder 9 has a required spring property. The carbon brush holder 9 is fixed to the motor case side via a bracket 11.

  In the configuration example of FIGS. 1 and 2, the front view shape of the carbon brush 15 is formed in an L shape, but may be formed in a T shape and a trapezoidal shape illustrated in FIGS. 5 and 6, respectively. . Further, the slidable contact portion 16 on the side in elastic contact with the commutator 7 in the carbon brush 15 is formed at the tip of an L-shaped, T-shaped or trapezoidal strip-shaped narrow portion (or a tapered narrow portion). ing. The width dimension W1 of the front end side sliding contact portion 16 is set to be smaller than the width dimension W2 of the holder fixing end (base end) portion 17 by a design value. Moreover, the width dimension W1 of the sliding contact portion 16 is set to be slightly larger than the gap dimension W3 between the adjacent terminals 13 of the commutator 7.

  Next, the operation of the embodiment will be described. Since the tip side sliding contact portion 16 of the carbon brush 15 has a flat surface in the initial state when it is new, as shown in FIG. 1, the sliding contact portion 16 of the carbon brush 15 and the outer peripheral surface of the commutator 7 Are in line contact with each other. However, with the use of the carbon brush 15, the tip surface of the sliding contact portion 16 is worn due to rotational friction with the outer peripheral surface of the commutator 7, and exhibits a concave curved surface that follows the outer peripheral surface of the commutator 7. It becomes like this. When the wear of the sliding contact portion 16 progresses, there is a problem that the generation rate of the electric signal is reduced in the brush shape of the conventional structure, but the problem is solved in the brush shape of the present embodiment.

That is, the L-shaped, T-shaped or trapezoidal carbon brush 15 according to the present embodiment forms the sliding contact portion 16 at the tip of the strip-shaped narrow width portion, and the narrow dimension W1 of the sliding contact portion 16 is as follows. , Commutator 7
The dimension is set to be slightly larger than the gap dimension W3 between the terminals 13. For this reason, even if the sliding contact portion 16 changes to a concave curved shape due to wear, the contact state similar to the line contact in the initial state can be maintained well. Therefore, the life characteristics of the carbon brush 15 are improved, and a normal electric signal is reliably generated as in the initial state.

  Further, since the sliding contact portion 16 of the carbon brush 15 is provided at the belt-like narrow end portion, unless the wear amount of the sliding contact portion 16 extends to the length (longitudinal dimension) L of the narrow portion. The contact state similar to the line contact in the initial state, that is, the state in which the contact area and the contact pressure are almost the same as the initial characteristics is maintained. As a result, even when the carbon brush 15 is used for a considerably long period of time as compared with the conventional case, the electrical signal characteristics in the conducting portion are almost the same as the initial characteristics, and the signal generation rate is not reduced.

  Further, in the L-shaped, T-shaped, or trapezoidal shape portion of the carbon brush 15, the base end portion 17 and the distal end side sliding contact portion 16 are formed in a wide portion and a wide detail, respectively. That is, the width dimension W2 on the base end portion 17 side is set to a required value or more, and the width dimension W1 of the distal end side sliding contact portion 16 is slightly larger than the distance dimension W3 between the adjacent terminals 13 of the commutator 7. Set to Therefore, while the shape of the brush is extremely simple, the contact strength of the carbon brush 15 with the commutator 7 is improved for a long period of time while the fixing strength of the carbon brush 15 is set to a necessary design value, and the life of the carbon brush 15 is improved. Remarkably improved.

  In the present invention, the slidable contact portion 16 of the carbon brush 15 may be provided at the tip of a narrow portion that exhibits a Mt. Fuji type tapered shape, as illustrated by an imaginary line 18 in FIG. 6. According to this configuration, the contact state equivalent to the initial line contact is stably maintained even when the amount of brush wear is considerably advanced as described above. Therefore, even if the carbon brush 15 is used for a long period of time, a highly reliable DC brush motor can be obtained without reducing the electric signal generation rate. In addition, the effective length of the carbon brush 15 is increased, and the time interval for performing the brush replacement is increased correspondingly, so that it is possible to operate without maintenance while ensuring a good rectifying action equivalent to the initial characteristics over a long period of time.

  As described above, in the present invention, the carbon brush 15 is made long by providing the sliding contact portion 16 at the stepped narrow width portion of the carbon brush 15 or the portion gradually narrowing in the tip direction. Even when used for a period, the sliding contact portion 16 is not worn so as to spread along the outer peripheral shape of the commutator 7, and the spread of the contact area during wear is effectively reduced. Further, the change in contact pressure per unit area with respect to the commutator 7 of the sliding contact portion 16 is reduced, and there is a change in initial characteristics between the carbon brush 15 and the commutator 7 due to wear, for example, the frequency characteristics of electrical signals. Less.

  The present invention has the same effect as that of the commutator 7 having a larger diameter. However, the change in the diameter of the commutator 7 is restricted by the product size of the motor and becomes difficult in design. In that respect, the above-described shape of the carbon brush 15 according to the present invention is not restricted by the shape and dimension of the motor product, and has an advantage of having a high degree of freedom in design.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

BRIEF DESCRIPTION OF THE DRAWINGS The whole block diagram which shows one Example by this invention and demonstrates a brush motor. Detailed drawing which shows the L-shaped brush part which concerns on an Example. The front view which shows the shape of the L-shaped brush which concerns on an Example. FIG. 4 is a side view of FIG. 3. Detailed drawing which shows the T-shaped brush part which concerns on an Example. Detailed view showing a trapezoidal brush portion according to the present invention. The whole block diagram which shows a prior art example and demonstrates the motor which has a brush. The side view of FIG. Detail drawing which shows the initial state of the brush part which concerns on a prior art example. Detail drawing which shows the abrasion state of the brush part which concerns on a prior art example.

Explanation of symbols

2 Rotor shaft 7 Commutator 9 Carbon brush holder 11 Bracket 12 Bracket cover 13 Terminal 15 Carbon brush 16 Sliding contact portion (tip side contact portion)
17 Holder side fixed end (base end side fixing part)

Claims (4)

  In a brush motor comprising a commutator having a plurality of terminals and rotating integrally with a rotor shaft, and a brush slidably in contact with the outer peripheral surface of the commutator, the width dimension of the sliding contact end portion of the brush is the width of the commutator. A brush motor characterized in that it is formed slightly larger than the gap dimension between terminals.   2. The brush motor according to claim 1, wherein the sliding contact end portion of the brush is provided at a tip end portion of a portion formed in a belt shape.   2. The brush motor according to claim 1, wherein the sliding contact end portion of the brush is provided at a tip portion of a tapered portion. 4. The brush motor according to claim 1, wherein the brush is formed in an L shape, a T shape, or a trapezoidal shape.

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