JPH0615483Y2 - Small motor with positive temperature coefficient thermistor - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention provides a small motor with a positive temperature coefficient thermistor, particularly by detecting the motor temperature and controlling overcurrent.
In a small motor with a positive temperature coefficient thermistor designed to prevent overheating of a small motor, by mounting the above positive temperature coefficient thermistor inside the motor cover plate, the response of the positive temperature coefficient thermistor is improved, and the overheat prevention function of the small motor is prevented. The present invention relates to a small motor equipped with a positive temperature coefficient thermistor which is capable of improving the size of the small motor and improving the productivity of the small motor.

[Conventional technology]

FIG. 6 is a block diagram of a well-known general small motor which is a premise of the present invention. The small motor shown in FIG. 6 is a commutator fixed to a motor shaft 24 supported by a terminal 21 whose current is held by the motor cover plate 1, a brush 22 in contact with the commutator 29, and a bearing 23. By being supplied to the rotor winding 20 wound around the rotor core 25 fixed to the motor shaft 24 via 29, by the permanent magnet 27 fixed to the inner peripheral surface of the motor case 26. The rotor 28 existing in the formed field is configured to rotate.

Small motors such as those shown in FIG. 6 can be used for automobile electrical equipment (eg, electric mirrors, power windows, etc.),
It has a wide range of applications as a drive source for electric toys and tape recorders. However, as a matter of course, the small motor has a low output, so even if the driven part suffers a minor malfunction (for example, rusting, dust intrusion, etc.), an overload condition (generally unrotatable condition) occurs. As a result, an undesired state in which the rotor winding 20 is overheated and eventually burned out may occur.

As a measure for preventing the rotor winding 20 from overheating, a method of using a bimetal, a fuse, or a heat sensitive element relay to cut off the current when overloaded is considered. However,
The bimetal method has poor operating characteristics at low voltage,
The fuse method has a drawback that the fuse needs to be replaced after the fuse is blown, and the thermal element relay method has a large circuit device.

As a measure against overheating for solving the above-mentioned drawbacks, as shown in FIG. 7, a method of supplying electric power from a power source 31 to a small motor 30 via a positive temperature coefficient thermistor 10 has been well known. The positive temperature coefficient thermistor 10
Are arranged so as to be in close contact with the inside of the small motor 30 or the surface of the motor case in order to effectively detect the temperature of the small motor 30.

The PTC thermistor 10 has a certain temperature (for example, 10
When the temperature exceeds 0 ° C., the internal resistance value rapidly increases. Therefore, the small motor 30 is overloaded continuously, or the small motor 30 is overloaded due to an overcurrent flowing when the rotation of the small motor 30 is forcibly locked.
When the temperature rises, the internal resistance value of the positive temperature coefficient thermistor 10 rapidly increases, so that it is possible to prevent the current supplied to the small motor 30 from rapidly decreasing and the small motor 30 from overheating.

[Problems to be Solved by the Invention] In a conventional small-sized motor having a positive temperature coefficient thermistor, the positive temperature coefficient thermistor is mounted outside or inside the motor so as to be closely attached to the motor case.

A small motor with a positive temperature coefficient thermistor mounted outside the motor requires an independent device that houses the positive temperature coefficient thermistor and has connecting terminals, etc., which not only increases the number of parts but also increases the number of mounting steps. Also increases and costs increase. Further, since it is attached to the outside of the motor, there is an undesired problem that an extra protruding portion is formed in terms of shape.

On the other hand, a small motor in which the PTC thermistor is mounted inside the motor requires a space for housing the PTC thermistor. Therefore, for example, an electric device having an overheat prevention function proposed in Japanese Utility Model Laid-Open No. 61-120226 has a structure in which the motor case is bulged to form an accommodation space for the positive temperature coefficient thermistor. However, in the case of this configuration, not only is it troublesome to process the motor case, but there is an undesired problem that an extra protrusion portion is formed in terms of shape.

Furthermore, the terminals of a small motor are often formed differently depending on the application of the small motor. And in the conventional small motor, when the shape of the terminal is different,
Since the motor cover plate holding the terminals has to be manufactured in different shapes corresponding to the terminals having different shapes, there is an undesired problem of poor productivity.

[Means for Solving the Problems]

The present invention is intended to solve the above problems, and therefore, a small motor having a positive temperature coefficient thermistor according to the present invention has a plurality of stator and rotor cores having permanent magnets for forming a field. And a rotor formed by winding individual rotor windings, and supplies a current to the rotor windings via a commutator that slidably contacts a brush for power supply supported in a motor cover plate. In a small motor having a positive temperature coefficient thermistor for controlling the current to the rotor winding, the motor cover plate has a pair of terminal holders for holding terminals, and the motor cover plate is electrically conductive. Of a conductive material and a pair of terminals having a fitting locking portion that is fitted and locked in the terminal holder, a pair of brush arms made of a conductive material, one of the brush arms, and one of the above A connecting member which is disposed so as to elastically contact the child and electrically connects the brush arm and the terminal, and an electrical connection between the connecting member which is disposed so as to elastically contact the other brush arm. A first pinching member that is electrically connected to the other terminal and a second pinching member that is disposed so as to elastically contact the other terminal and is electrically connected to the terminal. The technical means of adopting a structure in which the positive temperature coefficient thermistor is sandwiched and held between the sandwiching member and the second sandwiching member.

〔Example〕

1A to 1C are explanatory views for explaining a motor cover plate applied to the present invention. FIG. 1A is an inside front view of the motor cover plate, and FIG. B) is Fig. 1 (A)
A sectional view taken along the arrow AA in FIG. 1, FIG. 1C is a sectional view taken along the arrow BB in FIG. 1A, and FIG. 2 is a perspective view of each component mounted on the motor cover plate shown in FIG. FIG. 3 is an interior view of a motor cover plate according to an embodiment of the present invention, and FIG. 4 is an interior view of a motor cover plate according to another embodiment of the present invention.
FIG. 5 is a perspective view for explaining another embodiment of the sandwiching member applied to the present invention.

The present invention is a small-sized motor equipped with a positive temperature coefficient thermistor in which a common motor cover plate is used for a pin protruding type small motor for harness (the embodiment shown in FIG. 3) and a harness insertion type small motor (the embodiment shown in FIG. 4). A motor, which is a motor and is mounted on the motor cover plate used in the embodiment shown in FIGS. 3 and 4 prior to the description of the embodiment shown in FIG. 3 and the embodiment shown in FIG. A description of the parts will be provided in connection with FIGS. 1 and 2. In addition, reference numeral 1 in the drawing
Is a motor cover plate, 2 is a terminal holder, 3 is a protruding terminal insertion hole, 4 is a thermistor housing portion, 5 is a brush arm holder, 6 is a brush arm fitting groove, 7 is a connecting member housing portion, 8
Is a harness insertion hole, 9 is a bearing holding portion, 10 is a positive temperature coefficient thermistor, 11 is a holding member of FIG. 1, 12 is a second holding member, 11-1 and 12-1 are elastic contact portions, 11- 2 and 12-2 are slits, 13 is a brush arm, 14
Is a protruding terminal, 15 is an internal terminal, 14-1 and 15-1
Is a fitting locking portion, 14-2 and 15-2 are terminal portions, 16
Represents a connecting member.

In FIG. 1, the motor cover plate 1 is made of synthetic resin, and terminal holders 2 and 2 to which a pair of protruding terminals 14 or internal terminals 15 to be described later are fixed are integrally provided on the inner side surface. Further, brush arm holders 5 and 5 for holding the pair of brush arms 13 are integrally provided on the inner surface so as to project. Further, a groove-shaped thermistor housing portion 4 is formed in which the positive temperature coefficient thermistor 10 is housed and is sandwiched and held by the first sandwiching member 11 and the second sandwiching member 12. The protruding terminal insertion hole 3 is for inserting the terminal portion 14-2 of the protruding terminal 14, the harness insertion hole 8 is for inserting a power supply terminal (not shown) in the case of a harness insertion type small motor, and a bearing. The holding portion 9 is a portion to which a bearing for supporting a motor shaft (not shown) is mounted. By mounting the components shown in FIG. 2 on the motor cover plate 1, the embodiment shown in FIG. 3 or the embodiment shown in FIG. 4 is constructed.

In FIG. 3, a pair of projecting terminals 14 are shown as terminal holders 2.
It is fixed to. The protruding terminal 14 is configured by integrally forming a fitting locking portion 14-1 and a terminal portion 14-2, which are fitted and press-fitted into the terminal holder 2, and the terminal portion 14-2 is connected to the protruding terminal insertion hole 3 (first portion). (Refer to FIG. 1) while inserting into the fitting locking portion 14-1
Is fixed by fitting and press-fitting into the terminal holder 2. As shown in the figure, the pair of protruding terminals 14
The pair of protruding terminals 14 having the same shape can be used by mounting them in line symmetry. Further, the pair of brush arms 13 is press-fitted into a brush arm fitting groove 6 (see FIG. 1) formed around the brush arm holder 5.

Furthermore, the PTC thermistor 10 in a state of being sandwiched and held by the first sandwiching member 11 and the second sandwiching member 12 is housed in the thermistor housing portion 4 (see FIG. 1). The first sandwiching member 11 and the second sandwiching member 12 are each formed of a conductive spring material and, as shown in FIG. 2, an elastic contact portion protruding to one end edge. 11-1 and 12-1 are provided respectively,
Furthermore, slit portions 11-2 and 12 cut from the lower end of the position near the elastic contact portions 11-1 and 12-1.
-2 is formed. In addition, the first sandwiching member 11
The length dimension (the length from the tip of the elastic contact portion 11-1 to the other edge) of the thermistor accommodating portion 4 between one abutting portion (arrow 4a shown in FIG. 1) and the brush arm 13. The second sandwiching member 1 is made longer than the second sandwiching member 1 by a predetermined dimension.
The length dimension of 2 (the length from the tip of the elastic contact portion 12-1 to the other edge) is defined by the other abutting portion (arrow 4b shown in FIG. 1) of the thermistor accommodating portion 4 and the protruding terminal 14. It is formed to be longer than the distance by a predetermined dimension. Then, the first sandwiching member 11 is attached to the thermistor accommodating portion 4 such that the elastic contact portion 11-1 abuts on the brush arm 13 and the other end edge abuts on the abutting portion 4a. In the mounted state, the first holding member 1
The length dimension of 1 is the abutting portion 4a and the brush arm 13 described above.
Since the other end edge of the first sandwiching member 11 is in contact with the abutting portion 4a by a predetermined dimension longer than the distance between the elastic contact portion 11-1 and the brush arm 13, The contact pressure is sufficient to electrically connect the first sandwiching member 11 and the brush arm 13. The presence of the slit portion 11-2 can prevent undesired deformation of the elastic contact portion 11-1.

Further, the second sandwiching member 12 has the elastic contact portion 12-1.
Is attached to the thermistor accommodating portion 4 so as to contact the protruding terminal 14 and the other edge thereof to contact the abutting portion 4b. Even in the mounted state, the first sandwiching member 11
Similarly to the electrical connection between the brush arm 13 and the brush arm 13, the contact pressure of the elastic contact portion 12-1 with respect to the protruding terminal 14 is
This is sufficient for electrical connection between the second sandwiching member 12 and the protruding terminal 14.

As described above, the brush arm 13 and the protruding terminal 1
4 is the first pinching member 11 and the positive temperature coefficient thermistor 1
0 and the second sandwiching member 12 to ensure reliable electrical connection.

The other brush arm 13 and the protruding terminal 14 are electrically connected via a connecting member 16. That is, the connecting member 16 is formed of a conductive spring material, and the length dimension thereof is longer than the distance between the brush arm 13 and the protruding terminal 14 by a predetermined dimension. Therefore,
In the connecting member accommodating portion 7, the elastic force generated by the bending of the connecting member 16 when the connecting member 16 is mounted between the brush arm 13 and the protruding terminal 14 causes the brush arm 13 and the protruding terminal. The contact state with 14 is sufficient for electrical connection.

The embodiment shown in FIG. 4 is a so-called harness insertion type small motor, but basically has the same configuration and effect as the embodiment shown in FIG. That is, instead of the protruding terminal 14 in the embodiment shown in FIG. 3, the internal terminal 15 shown in FIG.
3 is exactly the same as the embodiment shown in FIG.

In FIG. 4, a pair of internal terminals 15 are shown as terminal holders 2.
It is fixed to. The internal terminal 15 includes a fitting locking portion 15-1 (having the same structure as the fitting locking portion 14-1 in the protruding terminal 14 shown in FIG. 3) and a terminal portion 15-2, which are fitted and press-fitted into the terminal holder 2. Are integrally formed, and the fitting locking portion 15
It is fixed by press-fitting -1 into the terminal holder 2. As shown in the drawing, by mounting the pair of internal terminals 15 in line symmetry, the pair of internal terminals 15 having the same shape can be used.
As described above, the other structure is exactly the same as that of the embodiment shown in FIG.

As described above, the present invention manufactures a small motor having different types of positive temperature coefficient thermistors because the other components can be commonly used by simply replacing the terminals even if the types of terminals are different. In this case, productivity can be significantly improved.

FIG. 5 shows another embodiment of the sandwiching member applied to the present invention, which is basically the same as the sandwiching member used in the embodiment shown in FIG. 3 and the embodiment shown in FIG. It has a structure. That is, by forming elastic bulging pieces, which will be described later, on the first sandwiching member 11 and the second sandwiching member 12 in the embodiment shown in FIG. 3 and the embodiment shown in FIG. The reliability of the electrical connection with the thermistor 10 is enhanced. In the figure, reference numeral 10 is a positive temperature coefficient thermistor, 17 is a first sandwiching member, and 18 is a second sandwiching member.
Sandwiching members 17-1 and 18-1 are elastic contact portions, 1
7-2 and 18-2 are slit portions, 17-3 and 1
Reference numeral 8-3 represents an elastic protrusion piece.

In FIG. 5, the elastic bulging piece 17-3 is formed by cutting out the other three sides of the first sandwiching member 17 that leave one side of the rectangular shape,
The positive temperature coefficient thermistor 10 is formed so as to bulge. Similarly, an elastic bulge piece 18-3 is also formed on the second sandwiching member 18. Therefore, the first sandwiching member 17 and the second sandwiching member 1 in the thermistor housing 4 are
When the PTC thermistor 10 is sandwiched and held by the first and second sandwiching members 17 and 18, and the PTC thermistor 10, the elastic swelling pieces 17-3 and 18-3 are connected to each other. Since they come into contact with each other firmly due to the elastic force, it is possible to improve the reliability of the electrical connection.

[Effect of device]

Since the present invention has the configuration and operation as described above, it does not require an independent device for accommodating a positive temperature coefficient thermistor, and can provide an overheat prevention function without increasing the number of parts, and is small in size. The productivity of the motor can be improved. Also, even if the type of terminal is different, other components can be used in common by simply replacing the terminal, which greatly increases the productivity when manufacturing small motors with different types of positive temperature coefficient thermistors. It is possible to improve. Further, the positive temperature coefficient thermistor can be housed and held in the motor cover plate, there is no need to bulge the motor case, and the shape and size of the small motor can be made compact and compact.

[Brief description of drawings]

1A to 1C are explanatory views for explaining a motor cover plate applied to the present invention. FIG. 1A is an inside front view of the motor cover plate, and FIG. B) is Fig. 1 (A)
A sectional view taken along the arrow AA in FIG. 1, FIG. 1C is a sectional view taken along the arrow BB in FIG. 1A, and FIG. 2 is a perspective view of each component mounted on the motor cover plate shown in FIG. FIG. 3 is an interior view of a motor cover plate according to an embodiment of the present invention, and FIG. 4 is an interior view of a motor cover plate according to another embodiment of the present invention.
FIG. 5 is a perspective view for explaining another embodiment of the sandwiching member applied to the present invention, and FIG. 6 is a configuration diagram of a well-known general small motor on which the present invention is based, and FIG. The figure shows an explanatory view for explaining the overheat prevention function by the positive temperature coefficient thermistor. In the drawing, 1 is a motor cover plate, 2 is a terminal holder, 3 is a protruding terminal insertion hole, 4 is a thermistor housing portion, 5 is a brush arm holder, 6 is a brush arm fitting groove, 7 is a connecting member housing portion, and 8 is Harness insertion hole, 9 bearing holding portion, 10 positive temperature coefficient thermistor, 11 and 17 first clamping member, 12
And 18 are second clamping members, 11-1, 12-1, 1
7-1 and 18-1 are elastic contact portions, 11-2, 12-
2, 17-2 and 18-2 are slit portions, 13 is a brush arm, 14 is a protruding terminal, 15 is an internal terminal, 14-1
And 15-1 are mating locking portions, 14-2 and 15-2
Represents a terminal portion, and 16 represents a connecting member.

Claims (1)

[Scope of utility model registration request] 1. A power supply unit having a stator having a permanent magnet for forming a field and a rotor having a plurality of rotor windings wound around a rotor core and being supported in a motor cover plate. A small motor having a positive temperature coefficient thermistor for controlling the current to the rotor winding, the current being supplied to the rotor winding through a commutator that is in sliding contact with the brush of The plate has a pair of terminal holders for holding terminals, and a pair of terminals having a fitting locking portion made of a conductive material and fitted and locked in the terminal holder in the motor cover plate, and a conductive member. A pair of brush arms made of a conductive material, a connecting member that is disposed so as to elastically contact one of the brush arms and one of the terminals, and electrically connects the brush arm and the terminal to each other, Up A first sandwiching member that is disposed so as to elastically contact the brush arm and is electrically connected to the brush arm; and a first sandwiching member that is disposed so as to elastically contact the other terminal and is electrically connected to the terminal. And a second sandwiching member that is electrically connected thereto, and a positive temperature coefficient thermistor is sandwiched and held between the first sandwiching member and the second sandwiching member. A small motor with a positive temperature coefficient thermistor.