JPS6350814Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a resistor for controlling a blower drive motor in a heating and cooling system installed in an automobile.

(Prior art) To adjust the strength of the wind from a blower, generally a resistor is connected in series with the blower drive motor, and by changing the resistance value of this resistor, the rotation speed of the motor is changed. ing.

Conventionally, this type of control resistor uses, for example, a plurality of coiled metal resistance wires connected in series, which are placed in a ventilation path, and when air is blown, the wind blows. It is forced to cool down. Therefore, if the motor stops for some reason, air cooling is lost, so the temperature of the resistor increases, and there is also a risk that the resistor will become red hot, melt, and fall. Ventilation channels are generally e.g.
Since it is made of resin such as ABS, if the resistor melts and falls, there is a risk of igniting surrounding combustible materials and causing a fire.

One way to prevent this kind of danger is to incorporate a temperature fuse into the resistor and connect it in series with the resistor so that when the temperature of the resistor rises abnormally, the fuse will blow out due to the heat. , so that the circuit would be cut off. However, with this method, there is a certain time lag before the fuse blows, so there is still a risk that the resistor will become red hot and fall during that time. Furthermore, if the fuse blows out, recovery is difficult and the entire resistor must be replaced, which is extremely uneconomical.

Another way to solve the above problem is to use a positive temperature characteristic resistance element (specifically, a positive temperature characteristic thermistor, hereinafter abbreviated as PTC) for the resistor of the control resistor.
It has been proposed to use As is well known, PTC has the characteristic that its resistance value increases rapidly and significantly when it exceeds a certain temperature (Kurie point), so as the temperature of the resistor increases, the resistance value of PTC increases, and therefore the metal It automatically limits the current at a lower temperature than when using a resistance wire, and the temperature of the resistor does not rise any further. This is extremely effective in terms of ensuring safety. However, the cost was 2.5 to 3 times higher than that using metal resistance wire, and this was a major factor in delaying its practical application.

(Purpose of the invention) The present invention aims to eliminate the drawbacks of the above-mentioned conventional example at once.It has a structure in which one PTC and multiple resistance elements made of metal resistance wire are connected in series and these are appropriately arranged. The present invention provides a resistor for controlling a blower of an automotive air conditioning system, which is small in size, low in cost, and highly safe. Hereinafter, embodiments will be described in detail based on the drawings.

(Embodiment) Fig. 1 shows an embodiment of the present invention, in which 1 is an insulating base plate made of resin or the like, and 2 is a base plate 1 on both sides of one side facing each other. A plurality of terminals are implanted in the terminals, 3a and 3b are resistance elements formed by forming metal resistance wire into a coil shape or a spring shape, and welded horizontally between the terminals 2 facing each other; 4 and 5 are respective support columns. A flat-shaped PTC 6 is sandwiched and held from above and below by a metal plate having 4a and 5a, and this PTC 6 is used as a resistor element 3a and 3b.
It is placed to cover the top. metal plates 4, 5
is connected to PTC6 by soldering etc.
It constitutes the terminal electrode of PTC6. In addition, the metal plates 4 and 5 are formed with cut and raised parts 4b and 5b, which serve as heat sinks and protect the internal resistance elements 3a and 3b together with the support columns 4a and 5a. It also serves as a protective cover. The bent portions 5c of the metal plate 5 shown in FIG. 1C are provided on both sides with the resistive elements 3a and 3b in between, and are intended to prevent the resistive elements 3a and 3b from coming into contact with the outside. Reference numeral 7 denotes a connector pin for connecting a changeover switch, which is connected to the terminal 2 and the metal plate supports 4a and 5a, respectively.

The coiled resistance elements 3a, 3b and the PTC 6 are connected in series, as shown in FIG. 2, and their input/output ends and connection points of each element are led out to connector pins 7, respectively. Figure 2 shows the motor control circuit, where 11 indicated by a broken line is the first
The control resistor 12 shown in the figure is a changeover switch, and the control resistor 11 and changeover switch 12 can be connected using, for example, a low-cost commercially available six-pole connector (commonly known as CN). Reference numeral 13 denotes a blower driving motor, which is connected to the H terminal of the changeover switch 12. In addition, in this case, one terminal of PTC6 is also H.
Connected to the terminal. 14 is a current fuse, 15 is a power switch, and 16 is a power source.

The control resistor configured as described above and connected as shown in Fig. 2 is installed in the ventilation path so that the wind direction is
It is installed in the direction of the arrow in Figure A. Now, if the power switch 15 is turned on and the selector switch 12 is connected to H (high), the current flowing to the motor 13 will not pass through the resistor 11, and the motor speed at this time will be maximum. switch 12
If connected to MH (medium high), the current will be
The current passes through PTC6 and is limited by its resistance, so the motor speed decreases somewhat compared to H. Next, when the switch 12 is switched to ML (medium low), the current passes through the PTC 6 and the resistive element 3a, so the current is further limited and the motor speed decreases.
When switched to (low), the current passes through the PTC 6 and the resistive elements 3a, 3b, so the current is most limited and therefore the motor speed is also the least. As can be seen from the above description, the present invention is configured such that the current always passes through the PTC in each motor speed setting stage except for the case of H.

(Effects of the invention) The present invention configured as described above has the following effects.

(1) When current flows through a resistor, it is configured to flow through a PTC, so other than one PTC, a coiled resistance element made of inexpensive metal resistance wire should be used to ensure sufficient safety. This results in a significant cost reduction compared to conventional PTC configurations, making it easier to put into practical use.
In addition, compared to the conventional example using a metal resistance wire and a temperature fuse, the cost increase remains within the range of 1.2 to 1.3 times.

(2) Using PTC, which is thin and has a large area,
Since this PTC is sandwiched between metal plates that have a wider area and are formed with cut and raised parts as heat dissipation fins, the heat dissipation effect during ventilation cooling (normal state) is extremely large, and therefore it can be made compact. - Can be configured compactly.

(3) In this way, the entire resistor is made small, and the flat parts of the PTC, the metal plate that clamps it, and its support are all arranged parallel to the wind direction of the ventilation path. Windage loss in the ventilation path is extremely small, and therefore the ventilation performance can be significantly improved.

(4) In the event of an abnormality in which air cooling stops due to motor locking, etc., the PTC, which is placed over the coiled resistance element, uses its large heat-receiving area to absorb direct radiant heat from the resistance element or by convection. In addition to receiving heat, it generates self-heating and can sensitively detect temperature rises. In other words, when the temperature of the resistor begins to rise due to the occurrence of an abnormality, the resistance value of the PTC increases rapidly with a response time of only about 5 seconds, compared to about 30 seconds with the conventional temperature fuse method. There is no red heat like that of a resistor, and it has extremely high safety against fire.

(5) In the event of an abnormality, the PTC's rapidly increasing resistance automatically limits the current to ensure safety, so once the abnormality is removed, the current will return to normal. Therefore, unlike the conventional temperature fuse method, there is no need to replace the resistor body, making it extremely economical.

(6) Furthermore, the present invention has a structure in which a commercially available inexpensive connector can be easily connected to the connector pin for connecting the changeover switch of the control resistor, thereby further reducing costs.

As explained above, according to the present invention, the difference between the heat dissipation coefficient during normal ventilation cooling and the heat dissipation coefficient during abnormal no-wind conditions can be idealized by the structure and arrangement of each component constituting the control resistor. The closer it is, the larger it can be, making it the most effective configuration for safety.

In addition, in the connection shown in FIG. 2, the changeover switch 12 is placed between the resistor 11 and the ground, but the
and the motor 13; in that case,
Connect the output end of the resistor to ground, and place the PTC closest to the ground.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention;
FIG. 2 is a motor control circuit diagram to which the resistor of the same embodiment is applied. 1... Base plate, 2... Terminal, 3a, 3b...
Coiled resistance element, 4, 5...Metal plate, 4a, 5
a... Support column, 4b, 5b... Cut and raised portion, 6...
PTC, 7... Connector pin, 11... Control resistor, 12... Changeover switch, 13... Blower drive motor.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of terminals embedded on both sides of the base plate so as to face each other, and a plurality of coiled resistance elements installed between the opposing terminals. and a support erected in the same direction as the terminal.
A flat positive temperature characteristic resistance element which is held between two metal plates and arranged so as to cover the upper part of the coiled resistance element is connected to each of the terminals and the pillars which are provided on the other surface of the base plate. The plurality of coiled resistance elements and the positive temperature characteristic resistance element are connected in series, and the input/output terminals and connection points of each element are respectively led out to the connector pin. A resistor for controlling a blower in an automotive air conditioning system. (2) Utility model registration claim No. (1) characterized in that the two metal plates each have a plurality of cut and raised parts and serve as the terminal electrodes and heat sink of the positive temperature characteristic resistance element. A resistor for controlling a blower in an automotive air conditioning system as described in 2.