JP5274770B2 - Small motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a positive characteristic thermistor from being forgotten to be inserted during the assembling a motor, and to operate the positive characteristic thermistor without impairing the operating characteristics thereof, in a small-sized motor, equipped with the positive characteristic thermistor. <P>SOLUTION: A terminal member 9 is arranged adjacent to one brush arm 8a, the positive characteristic thermistor 11, which controls a current flowing to an armature winding is sandwiched by the terminal member and the brush arm, and the one brush arm 8a and the terminal member 9 are arranged so as not to contact each other, in a state where they do not sandwich the positive characteristic thermistor 11. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a small motor provided with a positive temperature coefficient thermistor used in audio equipment, video equipment, automotive electrical equipment, and the like, and in particular, a small motor that prevents the positive temperature coefficient thermistor from being forgotten to be inserted during motor assembly. About.

  Conventionally, in a small motor with a brush, a motor in which a positive temperature coefficient thermistor is arranged as an overcurrent protection measure has been adopted. For example, in the case shown in FIG. 7, a brush arm 61 made of a conductive elastic material is formed in a substantially U shape on the case lid 60, and the brush 62 is fixed to one free end, while the other is A substantially planar connecting portion 63 is formed at the end along the inner end surface of the case lid 60.

Further, in the case lid 60, the internal terminal 64 is formed of a conductive elastic material similar to that of the brush arm 61, and a connection portion 65 is formed in which a portion extending into the case lid 60 is formed in a substantially V shape. A positive temperature coefficient thermistor 66 formed in a plate shape is sandwiched and held between the connection portion 63 of the brush arm 61 and the connection portion 65 of the internal terminal 64.
Utility Model Registration No. 25662736 (page 4, FIG. 7)

  However, in Patent Document 1, when it is forgotten to insert the positive temperature coefficient thermistor 66 during motor assembly, the connecting portion 65 of the internal terminal 64 presses the brush arm 61 to electrically energize to supply power to the small motor. Therefore, there is a possibility that the product may be shipped as it is, and there is a problem that safety for preventing overheating is lowered.

  Further, in order to securely hold the positive temperature coefficient thermistor 66 with only the elastic force of the internal terminal 64, it is necessary to increase the elastic force of the internal terminal 64. Therefore, a large pressure is applied to the positive temperature coefficient thermistor 66, and the positive characteristic There was a problem that the operating characteristics of the thermistor 66 deteriorated.

  SUMMARY OF THE INVENTION A main object of the present invention is to prevent a forgotten insertion of a positive temperature coefficient thermistor during motor assembly in a small motor equipped with a positive temperature coefficient thermistor, and to operate without impairing the operational characteristics of the positive temperature coefficient thermistor. is there.

A small motor according to the present invention includes a bottomed hollow cylindrical case, a permanent magnet fixed to an inner peripheral surface of the case, a rotor including an armature and a commutator facing the permanent magnet, A small size provided with a resin case lid attached to the opening, a pair of brushes arranged on the case lid and in sliding contact with the commutator, and a pair of brush arms electrically connected to the brush In the motor
A terminal member is disposed adjacent to one of the brush arms, and a positive temperature coefficient thermistor for controlling the current to the armature winding is sandwiched and attached between them.
One brush arm and the terminal member are arranged so as to be in non-contact with each other in a state where the positive temperature coefficient thermistor is not mounted.
The one brush arm and the terminal member are arranged so as to be in non-contact with each other even if the brush arm and the terminal member are shifted in a direction in which the positive temperature coefficient thermistor is sandwiched.
One of the brush arms and the terminal member has an elastic pressing portion that presses the positive temperature coefficient thermistor,
On the back side of the positive temperature coefficient thermistor pressed by the elastic pressing part, an elastic part for reducing this pressing force is provided ,
The elastic portion is formed of resin integral with the case lid on an inner peripheral surface of a bottomed hollow portion of the case lid .

The above-described small motor of the present invention has a further preferable feature as follows.
“At least one of the brush arm and the terminal member has a spring property ”,
Is included.

Since the small motor of the present invention is not electrically energized unless the positive temperature coefficient thermistor is mounted between the brush arm and the terminal member, it is surely removed in the inspection process if the positive temperature coefficient thermistor is forgotten to be mounted during motor assembly. It is possible to prevent the shipment of a device that is not equipped with a positive temperature coefficient thermistor.
Also, if the brush arm and the terminal member are provided with an elastic pressing portion, and the elastic portion that reduces this pressing force is provided on the back side of the positive temperature coefficient thermistor pressed by this, the pressing force can be increased. The operation can be performed without impairing the operation characteristics of the positive temperature coefficient thermistor.

  Hereinafter, the present invention will be described in detail with reference to the best mode for carrying out the invention shown in the drawings.

(First embodiment)
FIG. 1 is an exploded perspective view of a motor according to a first embodiment of the present invention. FIG. 2 is a completed plan view of the case lid according to the first embodiment of the present invention.

  Reference numeral 1 denotes a case, which is formed into a bottomed hollow cylindrical shape by a metal material such as soft iron, and a permanent magnet 2 is fixed to the inner peripheral surface. A rotor 5 including an armature 3 and a commutator 4 is configured to face the permanent magnet 2. Reference numeral 6 denotes a case lid which is formed of an insulating material such as a resin material and is fitted into the opening of the case 1. Reference numerals 7a and 7b denote a pair of brushes slidably contacted with the commutator 4, and brush arms 8a and 8b are electrically connected to the pair of brushes 7a and 7b, respectively. A terminal member 9 is disposed in the vicinity of one brush arm 8a. Reference numeral 10 denotes a bearing, which is fixed to the bottom portion of the case 1 and the center portion of the case lid 6, and the rotor 5 is rotatably supported by the bearing 10 to form a small motor 50.

  Reference numeral 11 denotes a positive temperature coefficient thermistor for controlling the current to the armature winding, and the one in this embodiment is formed in a quadrilateral plate shape, with a thickness in the thin direction of about 1 mm, a length of about 6 mm, and a width of about 7 mm. An electrode is attached to the electrode.

  The pair of brush arms 8a and 8b are arranged on the case lid 6 with the rotational axis symmetrical, and are formed in a substantially U shape by a conductive elastic material such as copper or copper alloy. Brushes 7a and 7b are fixed to one free end, and a substantially flat spring portion 12 disposed along the inner end surface of the case lid 6 is formed integrally with the spring portion 12 at the other end. Connected portions 13a and 13b are provided.

The terminal member 9 is formed of the same conductive elastic material as that of the brush arm, and has a substantially L-shape as a whole. The external connection unit 15 is supplied with current from an external DC power supply.
The pair of brush arms 8 a and 8 b and the terminal member 9 are mounted via a holder 16 provided on the case lid 6.

  The case lid 6 is formed with a bottomed hollow portion 17 that is open only on the inner surface, and the connection portion 13a of one brush arm 8a and the internal connection portion 14 of the terminal member 9 that is adjacent thereto are inserted into the bottomed hollow portion 17. Is done. As shown in FIG. 2, in the bottomed hollow portion 17, the connection portion 13a of one brush arm 8a and the internal connection portion 14 of the terminal member 9 are inserted substantially parallel to the positive temperature coefficient thermistor 11, and these The positive temperature coefficient thermistor 11 is sandwiched between them, and the internal connection portion 14 and the connection portion 13a are electrically connected to the electrodes on both sides of the positive temperature coefficient thermistor 11.

  3 is a cross-sectional view taken along the line AA in FIG. 2 showing a state in which the connecting portion 13a of the brush arm 8a, the internal connecting portion 14 of the terminal member 9, and the positive temperature coefficient thermistor 11 are mounted on the bottomed hollow portion 17 of the case lid 6. It is.

  The connecting portion 13a of one brush arm 8a and the internal connecting portion 14 of the terminal member 9 provided in the vicinity thereof are provided with elastic pressing portions 18a and 18b having a cross-sectional shape, respectively, to the positive temperature coefficient thermistor 11. The electrical connection can be made more reliable.

  On the back side of the positive temperature coefficient thermistor 11 pressed by the elastic pressing portions 18a and 18b, an elastic portion 19 for reducing the pressing force is provided on the inner peripheral surface of the bottomed hollow portion 17 of the case lid 6. Two elastic portions 19 are formed on the inner peripheral surface of the bottomed hollow portion 17 and are substantially parallel to each other in the axial direction by a resin integral with the case lid 6.

  Further, the case lid 6 is provided with a through hole (not shown) corresponding to the connection portion 13 b of the other brush arm 8 b and the external connection portion 15 of the terminal member 9. When the connecting portion 13b of the brush arm 8b and the external connecting portion 15 of the terminal member 9 are inserted into this through-hole, it protrudes to the outer surface of the case lid 6 and can supply current from an external DC power source, thereby driving the motor. be able to.

  The positive temperature coefficient thermistor 11 has a characteristic that the internal resistance value suddenly increases when a certain temperature (for example, 100 ° C.) is exceeded, and an overload is continuously applied to the small motor 50 or the rotation of the rotor. When the temperature of the small motor 50 rises due to an overcurrent that flows when is forcibly locked, the internal resistance value of the positive temperature coefficient thermistor 11 rapidly increases. Therefore, it is possible to prevent the current supplied to the small motor 50 from rapidly decreasing and the small motor 50 from being overheated.

  Thus, in the small motor 50 of the present embodiment, the positive temperature coefficient thermistor 11 is mounted between one brush arm 8a and the terminal member 9, and the internal connection portion 14 and the connection portion 13a are connected to the electrodes on both surfaces of the positive temperature coefficient thermistor 11. Are electrically connected to the armature 3 from an external DC power source (not shown) via the terminal member 9, the positive temperature coefficient thermistor 11, the brush arm 8, the brush 7, and the commutator 4. When a current is supplied to 3, a rotational force is applied to the armature 3 in the magnetic field by the permanent magnet 2 fixed to the inner peripheral surface of the case 1, and the rotor 5 can be rotated.

On the other hand, when the positive temperature coefficient thermistor 11 is not mounted, power is not supplied to the armature 3.
Specifically, in this embodiment, the connecting portion 13a of one brush arm 8a and the internal connecting portion 14 of the terminal member 9 provided in the vicinity thereof are arranged substantially in parallel with the positive temperature coefficient thermistor 11 interposed therebetween, and the connecting portion 13a The internal connection portion 14 is disposed at a position that does not overlap with each other when viewed from the thickness direction of the positive temperature coefficient thermistor 11. When the positive temperature coefficient thermistor 11 is not sandwiched, the connection portion 13 a and the internal connection portion 14 are not in mechanical contact with each other. Thus, it becomes electrically non-conductive.

  Therefore, if the positive temperature coefficient thermistor 11 is not inserted between the brush arm 8a and the terminal member 9 during motor assembly, it is not electrically energized, so that the non-insertion of the positive temperature coefficient thermistor 11 can be detected in the inspection process. It is possible to prevent shipment of a motor for which the thermistor 11 is forgotten to be inserted.

  Further, in this embodiment, the brush arm 8a and the terminal member 9 are mounted via the holder 16, but the connecting portion 13a is formed at the end of the brush arm 8a having a substantially U-shaped elastic force. In addition, since the internal connection portion 14 is entirely at the end of the terminal member 9 having an elastic force formed in a substantially L shape, for example, the connection portion 13a of the brush arm 8 and the terminal member 9 due to an impact during transportation or the like. There is a possibility that the internal connection portion 14 in the bottomed hollow portion 17 changes in the thickness direction of the positive temperature coefficient thermistor 11 (that is, the direction in which the positive temperature coefficient thermistor is sandwiched) with the holder 16 as a fulcrum.

However, in the present embodiment, the connection portion 13a and the internal connection portion 14 are arranged at positions that do not overlap each other when viewed from the thickness direction of the positive temperature coefficient thermistor 11, and therefore, the connection portion 13a of the brush arm 8 and the inside of the terminal member 9 are assumed. Even if the connecting portion 14 is displaced in the direction in which the positive temperature coefficient thermistor 11 is sandwiched, they do not contact each other.
For this reason, it can prevent more reliably that the positive temperature coefficient thermistor 11 is shipped without insertion.

  The brush arm 8a and the terminal member 9 of the present embodiment both have elastic force (spring property). However, if at least one of the brush arm 8a and the terminal member 9 has spring property, the motor When the finished product is incorporated in audio equipment, video equipment, automotive electrical equipment, etc., even if vibration or impact is applied to the motor from those equipment, the brush arm 8a and the terminal member 9 are correctly Since the characteristic thermistor 11 can be clamped, the positive characteristic thermistor 11 can be mechanically held and reliably connected electrically.

  Further, in this embodiment, the brush arm 8a and the terminal member 9 are provided with elastic pressing portions 18a and 18b that press the positive characteristic thermistor 11, and this pressing force is reduced on the back side of the positive characteristic thermistor 11 that is pressed by the elastic thermistors 11. An elastic part 19 is provided on the inner peripheral surface of the bottomed hollow part 17 of the case lid 6. For this reason, even if the elastic force of the brush arm 8a and the terminal member 9 is increased in order to connect the positive temperature coefficient thermistor 11 securely and securely, the pressing force applied to the positive temperature coefficient thermistor 11 can be reduced. The operation can be performed without impairing the operation characteristics.

(Second Embodiment)
FIG. 4 is a completed plan view of the case lid according to the second embodiment of the present invention.
In FIG. 4, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. This embodiment is different from the first embodiment in that the connection portion 13a of one brush arm 8a and the internal connection portion 14 of the terminal member 9 are conductive coil springs 30. With such a configuration, even if the elastic force is increased, the pressure applied to the positive temperature coefficient thermistor 11 can be reduced, and the operation can be performed without impairing the operational characteristics of the positive temperature coefficient thermistor 11.

(Third embodiment)
FIG. 5 is a completed plan view of the case lid according to the third embodiment of the present invention.
In FIG. 5, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, the difference from the first embodiment is that the connecting portion 13a of one brush arm 8a and the internal connecting portion 14 of the terminal member 9 are conductive flat terminals 31, and have a bottom. The elastic part 19 provided on the inner peripheral surface of the hollow part 17 is a point having a U-shape 32 having a spring property extending from the case lid 6. Even in such a shape, the effect as in the second embodiment can be obtained.

(Fourth embodiment)
FIG. 6 is a completed plan view of the case lid according to the fourth embodiment of the present invention.
In FIG. 6, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, the difference from the first embodiment is that the connecting portion 13a of one brush arm 8a and the internal connecting portion 14 of the terminal member 9 are conductive flat terminals 31, and press the terminals 31. The coil spring 33 is provided. Even in such a shape, the effect as in the second embodiment can be obtained.

  In the embodiment described above, a positive temperature coefficient thermistor 11 having a quadrilateral plate shape and electrodes attached to both sides is used, but this positive temperature coefficient thermistor 11 may be a round plate shape or a polygonal plate shape, Alternatively, two electrodes may be provided on one side. In the case where two electrodes are provided on one side, it is desirable that the connection part 13a and the internal connection part 14 are arranged substantially parallel to the positive temperature coefficient thermistor on one side and are not in mechanical contact with each other.

  Further, the present invention is not limited to the above-described embodiments, and can be appropriately modified and implemented without departing from the gist of the present invention.

1 is an exploded perspective view of a motor according to a first embodiment of the present invention. It is a completion top view of a case lid concerning a 1st embodiment of the present invention. It is AA sectional drawing of FIG. 2 of the case cover concerning the 1st Embodiment of this invention. It is a completion top view of a case lid concerning a 2nd embodiment of the present invention. It is a completion top view of a case lid concerning a 3rd embodiment of the present invention. It is a completion top view of a case lid concerning a 4th embodiment of the present invention. It is a top view which shows the case cover of the conventional motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Permanent magnet 3 Armature 4 Commutator 5 Rotor 6 Case cover 7a Brush 7b Brush 8a Brush arm 8b Brush arm 9 Terminal member 10 Bearing 11 Positive characteristic thermistor 12 Spring part 13a Connection part 13b Connection part 14 Internal connection part 15 External connection portion 16 Holder 17 Bottomed hollow portion 18a Elastic pressing portion 18b Elastic pressing portion 19 Elastic portion 30 Conductive coil spring 31 terminal 32 U-shaped 33 Coil spring 50 Small motor 60 Case lid 61 Brush arm 62 Brush 63 Connection portion 64 Internal terminal 65 Connection 66 Positive Characteristics Thermistor

Claims (2)

A bottomed hollow cylindrical case, a permanent magnet fixed to the inner peripheral surface of the case, a rotor composed of an armature and a commutator facing the permanent magnet, and a resin attached to the opening of the case In a small motor provided with a case lid made of, a pair of brushes arranged on the case lid and slidably contacted with the commutator, and a pair of brush arms electrically connected to the brush,
A terminal member is disposed adjacent to one of the brush arms, and a positive temperature coefficient thermistor for controlling the current to the armature winding is sandwiched and attached between them.
One brush arm and the terminal member are arranged so as to be in non-contact with each other in a state where the positive temperature coefficient thermistor is not mounted.
The one brush arm and the terminal member are arranged so as to be in non-contact with each other even if the brush arm and the terminal member are shifted in a direction to sandwich the positive temperature coefficient thermistor,
One of the brush arms and the terminal member has an elastic pressing portion that presses the positive temperature coefficient thermistor,
On the back side of the positive temperature coefficient thermistor pressed by the elastic pressing part, an elastic part for reducing this pressing force is provided ,
The small motor , wherein the elastic portion is formed of a resin integral with the case lid on an inner peripheral surface of a bottomed hollow portion of the case lid . The small motor according to claim 1, wherein at least one of the brush arm and the terminal member has a spring property.

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