JPH0717249Y2 - Motor with overcurrent protection element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a device for limiting an overcurrent flowing through a coil in a motor including a rotor around which a coil is wound.

[Prior art and its problems]

Conventionally, an blower motor circuit of an air conditioner has been provided with an overcurrent protection element to prevent a burnout accident when the motor is abnormally locked, and it has been proposed to use a positive temperature coefficient thermistor as the overcurrent protection element.

However, in the conventional case, since the PTC thermistor is installed at a location away from the motor body, even if the motor overheats due to internal factors or external factors, the PTC thermistor cannot detect it sensitively. In some cases, the motor could not be sufficiently protected. Moreover, a board for mounting the positive temperature coefficient thermistor is required, increasing the mounting space,
There is a problem that the processing man-hour and the cost increase.

[Purpose of device]

The present invention has been made in view of the above problems, and an object thereof is to improve reliability by positively sensing a positive temperature coefficient thermistor against abnormal overheating of a motor and to reduce the size of a motor part including the positive temperature coefficient thermistor. It is to provide an inexpensive motor with an overcurrent protection element that can be realized.

[Constitution of device]

The motor with overcurrent protection device of the present invention is one in which a ring-shaped positive temperature coefficient thermistor having electrodes formed on both end surfaces is inserted and fixed to the rotary shaft of a rotor, and the positive temperature coefficient thermistor is connected in series to a coil. Is.

[Action]

That is, when an overcurrent flows in the circuit during abnormal lock or the like, the resistance value suddenly increases due to self-heating of the positive temperature coefficient thermistor, so that the value of the current flowing through the coil is limited and burnout of the coil is prevented in advance.

Further, since the positive temperature coefficient thermistor is formed in a ring shape and is inserted and fixed to the rotating shaft of the rotor, a large mounting space is not required and uneven rotation is not given to the rotor.
Moreover, since the PTC thermistor is mounted near the coil, which is the heat generating part when an overcurrent flows, and is attached to the rotating shaft that has better heat conduction than the air layer, it has good thermal sensitivity. The heat of the coil can be sensed sensitively.

〔Example〕

1 to 3 show an example of a motor M with an overcurrent protection element according to the present invention. The motor M is an example of a commutator motor, and includes a case 1 having a permanent magnet 2 fixed therein as shown in FIG. 1, a cover 3 fitted to one end of the case 1, a case 1 and a cover 3. The rotor 10 is housed inside.

Inside the cover 3, as shown in FIG. 2, two brushes 4,
5 is fixed, and lead wires 6 and 9 are connected to the brushes 4 and 5, respectively, and lead out to the outside.

The rotor 10 has a rotating shaft 11 whose both ends are rotatably supported by a case 1 and a cover 3, and is fixed to the rotating shaft 11 and has a coil 13
The iron core 12 wound with, and connected to both ends of the coil 13,
Commutators 14a, 14 fixed along the outer peripheral surface of the rotating shaft 11
It consists of b and. The brush 4 is attached to the commutator 14a, 14b,
5 is pressed elastically.

A positive temperature coefficient thermistor 21 is attached to the rotor 10. That is, the positive temperature coefficient thermistor 21 is formed in a ring shape as shown in FIG. 3, and electrodes 21a (the back surface side is not shown) are formed on both end surfaces thereof. The PTC thermistor 21 is inserted into the rotary shaft 11, and the commutator 14a which is divided into two in the axial direction and the electrodes 21a on both surfaces of the PTC thermistor 21 are connected in series by soldering or the like.

In this embodiment, by only changing the commutator 14a of the rotor 10, the other motor components can be used as they are, and the positive temperature coefficient thermistor 21 can be attached in a position close to the coil 13. , The heat of the coil 13 can be detected quickly.

Further, since the positive temperature coefficient thermistor 21 is formed in a ring shape and is inserted and fixed to the rotary shaft 11 of the rotor 10, a large mounting space is not required and the rotor 10 is not unevenly rotated. Moreover, since the electrode 21a of the PTC thermistor 21 can be directly soldered to the commutator 14a, the PTC thermistor 21
The lead wire for connecting the coil 13 and the coil 13 in series becomes unnecessary.

The motor M having the above structure is used, for example, in the circuit structure shown in FIG. That is, the motor M is connected in series with the power supply 16 together with the positive temperature coefficient thermistor 21 and the load 15. Therefore, if the motor M abnormally locks, an overcurrent temporarily flows in the circuit, but the positive temperature coefficient thermistor 21 is affected by self-heating and the heat generation of the coil 13 and the resistance value suddenly rises to cause an overcurrent. The speed can be limited and the motor M can be protected.

Needless to say, the motor according to the present invention is not limited to the motor having the structure of the embodiment.

[Effect of device]

As is clear from the above description, the motor with overcurrent protection device of the present invention is thermally coupled by mounting a positive temperature coefficient thermistor near the coil part, so when overcurrent flows in the circuit due to abnormal lock or the like. As a result, the resistance value of the positive temperature coefficient thermistor is promoted by the heat generated in the coil portion, and the operation of the positive temperature coefficient thermistor can be made much faster than before.

Further, since the positive temperature coefficient thermistor is formed in a ring shape and is inserted and fixed to the rotary shaft of the rotor, it does not require a large space and does not give uneven rotation to the rotor. Moreover, since the PTC thermistor is mounted near the coil, which is the heat generating part when an overcurrent flows, and is attached to the rotating shaft that has better heat conduction than the air layer, it has good thermal sensitivity. The heat of the coil can be sensed sensitively.

Furthermore, since the PTC thermistor can be efficiently placed in the dead space inside the motor, the board for mounting the thermistor is no longer required as in the past, and the wiring does not require a mounting space and the wiring can be simplified. A motor with a current protection device can be obtained.

Also, by mounting the PTC thermistor integrally with the rotor, it is possible to increase the operating current value of the PTC thermistor compared to when there is no wind, due to the wind generated by the rotation of the motor during normal use. Has the advantage that it can be further miniaturized.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an example of a motor with an overcurrent protection device according to the present invention, FIG. 2 is a sectional view of the motor, FIG. 3 is an enlarged perspective view of a positive temperature coefficient thermistor, and FIG. is there. M ... Motor, 1 ... Case, 2 ... Permanent magnet, 3 ... Cover,
4,5 ... Brush, 10 ... Rotor, 12 ... Iron core, 13 ... Coil, 14
a, 14b ... commutator, 21 ... positive characteristic thermistor, 21a ... electrode.

Claims (1)

[Scope of utility model registration request] 1. In a motor including a rotor around which a coil is wound, a ring-shaped positive temperature coefficient thermistor having electrodes on both end surfaces is fixedly inserted through a rotary shaft of the rotor, and the positive temperature coefficient thermistor is used as a coil. A motor with an overcurrent protection device, which is connected in series with the motor.