JPS5926562Y2 - Device for current control - Google Patents

Description

[Detailed description of the invention] The present invention relates to a current control device, and in particular to a barium titanate-based semiconductor porcelain (hereinafter referred to as "barium titanate semiconductor porcelain") having a positive resistance temperature characteristic for switching the rotation speed of a blower motor etc. and preventing overcurrent in abnormal situations. It is called a positive characteristic thermistor.

). Conventionally, nichrome heaters have been used to change the rotation speed of automobile blower motors, but when the blower stops, it generates too much heat and there is a risk of overheating and breaking the wire.

Therefore, in order to prevent this, it was necessary to provide a separate temperature control means.

On the other hand, positive temperature coefficient thermistors are used as heating elements and
Although it has also been used as a current limiting element, its resistance value has been relatively large and it has not been suitable for automobiles where the power supply voltage is as low as 12V or 24V.

In view of the above points, the present invention has been developed by connecting a plurality of positive temperature coefficient thermistors in which electrodes are formed on the front and back surfaces of a thin plate-shaped positive coefficient thermistor body, so that the resistance value is sufficiently low at normal operating temperatures, and the resistance value is abnormal. It is an object of the present invention to provide a current control device having a function of limiting current at times.

Embodiments of the current control device according to the present invention will be described below with reference to the drawings.

1 and 2, a current control device 1 includes ohmic electrodes 3 on the front and back surfaces of a thin positive temperature coefficient thermistor body 2.
A positive temperature coefficient thermistor 4A in which a through hole 8 is formed and a through hole 8 is formed.
, 4B, 4C, and each positive characteristic thermistor 4A, 4B, 4C
In this structure, electrode plates/heat sinks 5 which are in close contact with the ohmic electrodes 3 and have through holes 9 are stacked alternately and are tightened with bolts 6 and nuts 7 to integrate them.

Here, the area of the ohmic electrode 3 of the PTC thermistor 4B is smaller than that of the PTC thermistor 4A, and the area of the ohmic electrode 3 of the PTC thermistor 4C is further smaller.

Therefore, (resistance value of positive characteristic thermistor 4A) < (resistance value of positive characteristic thermistor 4B) < (positive characteristic thermistor 4C
resistance value).

Further, the heat sink plate 5 which also serves as an electrode plate has a terminal portion 5A for connection.

In the above embodiment, the resistance values of the plurality of PTC thermistors are made to differ from each other by changing the electrode area 3 of the PTC thermistor 2, but the resistance values can be changed by changing the thickness of the PTC thermistor 2. Good too.

Furthermore, by changing both the electrode area and thickness, the resistance value can be changed more widely.

FIG. 3 shows an example of application of the current control device 1.

In this figure, a current control device 1 is connected at each terminal portion 5A between a blower motor 10 and a power source 11 via a switch 12, and the switch 12 switches the number of positive characteristic thermistors connected in series to the blower motor 10. I have to.

In this case, if the blower motor 10 is operating normally,
The positive temperature coefficient thermistors 4A to 4C of the current control device 1 are cooled by the wind W from the blower 13, and their operating range is the range indicated by the symbol A in FIG.

That is, each of the positive characteristic thermistors 4A to 4C maintains a sufficiently low predetermined resistance value, and the current value flowing to the blower motor 10 can be controlled in response to the switching operation of the switch 12, and the rotation speed of the blower motor 10 can be changed. can.

Further, when the blower motor 10 stops due to some abnormality, the positive temperature coefficient thermistors 4A to 4C are no longer cooled and generate heat, and their resistance value increases rapidly.

As a result, the current of the blower motor 10 is rapidly reduced and is substantially cut off.

Thus, the blower motor 10 and power supply 11 can be protected.

In this manner, the current control device 1 is capable of not only normal current control but also current interruption in the event of an abnormality, and therefore can be used to protect motor circuits, power supply circuits, and the like.

In addition, by forming ohmic electrodes 3 on the front and back surfaces of the thin plate-shaped positive temperature coefficient thermistor body 20, the positive temperature coefficient thermistor 4A
4C, it was possible to achieve a low resistance value that could never be obtained with conventional positive temperature coefficient thermistors.

Therefore, it can be fully used in automobiles with low power supply voltage.

FIG. 5 shows another example of application.

In this figure, the connections between the positive temperature coefficient thermistors 4A to 4C of the current control device 1 and the switch 12 are partially different.

In this case as well, the positive characteristic thermistor inserted in series with the blower motor 10 can be changed by switching the switch 12, and the rotation speed of the blower motor 10 can be changed and the current can be cut off in the event of an abnormality.

In the above embodiment, a plate-shaped heat dissipation plate 5 that also serves as an electrode frame is used, but in order to improve the heat dissipation effect, fins or the like may be formed on the heat dissipation plate 5 that also serves as an electrode plate, or the side surface of the heat dissipation plate 5 that serves as an electrode plate may be formed. The heat radiation effect can be improved by adding heat radiation fins to the.

As shown above, according to the present invention, by connecting a plurality of positive temperature coefficient thermistors in which electrodes are formed on the front and back surfaces of a thin plate-shaped positive coefficient thermistor element body, a sufficiently low resistance value is exhibited at normal operating temperatures. Moreover, a current control device having a function of limiting the current in the event of an abnormality is obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the current control device according to the present invention, FIG. 2 is an exploded perspective view of the same, and FIG. 3 is a circuit diagram showing an application example of the current control device shown in the embodiment. FIG. 4 is a graph for explaining the operating range of the positive temperature coefficient thermistor of the current control device, and FIG. 5 is a circuit diagram showing another example of application. 1... Current control device, 2... Positive temperature coefficient thermistor element, 3... Ohmic electrode, 4A,
4B, 4C...Positive characteristic thermistor, 5...
・・Electrode plate/heat sink, 6... Bolt, 7...
...Natsuto.

Claims (2)

[Scope of utility model registration request] (1) A current control device in which a plurality of positive temperature coefficient thermistors in which ohmic electrodes are formed on the front and back surfaces of a thin plate-shaped positive coefficient thermistor body are connected with a heat sink that also serves as an electrode plate interposed therebetween,
A current control device characterized in that the plurality of positive temperature coefficient thermistors have mutually different resistance values. (2) Utility Model Registration The current control device according to claim 1, wherein the plurality of positive temperature coefficient thermistors are different in at least one of electrode area or thickness.