JPS6238809Y2 - - Google Patents

Description

[Detailed Description of the Invention] In the present invention, a temperature fuse and a plurality of resistors are provided in series with a fan motor, and by switching these plurality of resistors by a fan switch,
The present invention relates to a device for easily detecting the blowing of a temperature fuse in an automotive air conditioner that adjusts the rotational speed of a fan motor.

As a conventional air conditioner for automobiles, there is one shown in FIG. That is, battery 10
A fan motor 20, a temperature fuse 30, and a plurality of resistors 41, 4 are connected in series with each other via a main fuse.
2 and 43 are connected in series. The rotational speed of the fan motor 20 is adjusted by switching these resistors 41, 42, and 43 using the fan switch 40. And Compressa 5
The first magnetic clutch coil 50 connects the switch 11 and the grounding contact 44 of the fan motor 40.
is established between.

In the above automotive air conditioner, the fan switch 40 is set to H (high speed), MH (medium high speed), and ML.
(medium-low speed) and L (low speed), the fan motor 20 rotates at each speed, and at this time the coil 50 is energized and the clutch is engaged, so the compressor 51 is also driven by the engine. In this state, if the temperature fuse 30 is blown for some reason, the motor 20 will stop, but the compressor 51 will continue to drive because the coil 50 is energized. This causes the evaporator to freeze and the compressor 51 to
may be destroyed. In this way fuse 30
If the motor 20 stops rotating due to the fan motor 20 being cut off, wind will not blow out from each duct and the rotation sound of the fan motor 20 will not be heard.
The crew should know that fuse 30 is blown.

However, even in such a case, it may not always be possible to know that the fuse 30 has blown because the driver is concentrating on driving or for other reasons.

Therefore, the present invention provides an air conditioner for an automobile in which a temperature fuse and a plurality of resistors are provided in series with a fan motor, and the rotational speed of the fan motor is adjusted by switching the plurality of resistors with a fan switch. In order to easily detect that the temperature fuse is blown, a voltage detection circuit is provided that outputs an output when the voltage across the temperature fuse and its series resistor is equal to or higher than a predetermined value.

The present invention will be described in detail below based on embodiments shown in the accompanying drawings.

FIG. 2 is a circuit diagram showing an embodiment of the present invention. Note that the same members are given the same reference numerals. The connection point between the fan motor 20 and the temperature fuse 30 is designated as A, and the connection point between the resistor 41 and the resistor 42 is designated as B. A differential amplifier 60 is provided which receives points A and B as inputs. Further, resistors 71 and 72 are provided between the connection point between the switch 11 and the fan motor 20 and the ground, and the connection point between the resistors 71 and 72 is designated as C. A comparator 70 whose inputs are this point C and the output of the differential amplifier 60 is provided, and a warning lamp 73 is provided between the output and ground. Further, a coil of a normally closed relay 80 is connected between the output of the comparator 70 and ground. Further, the switch 11, the normally closed contact of the relay coil 80, the magnetic clutch coil 50, and the contact 44 of the fan switch 40 are connected in series.

Next, the operation of the above embodiment will be explained.

First, when the switch 11 is turned on and the fan switch 40 is connected to any point H, MH, ML, or L, the fan motor 20 rotates at the respective speed, and the magnetic clutch coil 50 is excited, and a compressor 51 is driven by the engine via a belt. Here, the voltage of battery 10 is 12V, and the voltage at point C is 10V.
Suppose it is set to . In this case, if the fan switch 40 is connected to point H, current flows directly without passing through the fuse 30, but the resistance of the main fuse and motor 20 is almost negligible, and the resistance 41 Since no current flows, the difference between the potential at point A and the potential at point B is approximately OV
Therefore, the output of the differential amplifier 60 is approximately
It is OV. Therefore, the comparator 70 does not output,
The warning lamp 73 does not light up, the relay 80 remains on, and the compressor 51 is driven. Furthermore, when the fan switch 40 is connected to any of the points MH, ML, and L, the resistors 41, 42, and 4
The potential difference between point A and point B is about 3 to 4 V, although it varies somewhat depending on the resistance of point A and point B, so differential amplifier 6
0 produces an output of 3-4V. However, since the voltage at point C is 10V, the comparator 70 does not output an output, the warning lamp 73 does not light up, and the compressor 51 is driven, as in the case described above. Also fan switch 4
0 is off, fuse 30 and each resistor 4
Since no current flows through 1, 42, and 43, the differential amplifier 60 does not output, and the comparator 70 also does not output, so the warning lamp 73 does not light up in the same way as above, and the ground of the coil 50 is opened. Therefore, the compressor 51 does not rotate.

On the other hand, if the switch 11 is turned on and the fan switch 40 is connected to any point H, MH, ML, or L, and the temperature fuse 30 is blown for some reason, the voltage at point A will be 12V
Since the voltage at point B is OV, the differential amplifier 60 outputs 12V, and since the voltage at point C is 10V, the comparator 70 outputs an output, which lights up the warning lamp 73. to notify that the fuse is blown. Further, in this case, the relay 80 is turned off and the compressor 51 stops driving. Therefore, if the temperature fuse 30 blows out even though the automobile air conditioning system should normally operate, the warning lamp 73 will light up, making it clear to the occupants that the temperature fuse 30 has blown. This can be easily detected, and in that case, the compressor 51 automatically stops driving to protect the evaporator. In addition, lamp 73, relay 80
Either one may be omitted.

As described above, the present invention provides an automotive vehicle in which a temperature fuse and a plurality of resistors are provided in series with a fan motor, and the rotational speed of the fan motor is adjusted by switching the plurality of resistors with a fan switch. In the air conditioner, by providing a voltage detection circuit that outputs when the voltage across the temperature fuse and its series resistor exceeds a predetermined value, it is possible to easily detect that the temperature fuse is blown. .

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a conventional air conditioner for an automobile, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 10...Battery, 20...Fan motor,
30... Temperature fuse, 41, 42, 43... Speed control resistor, 50... Magnetic clutch coil, 60... Differential amplifier, 70... Comparator, 7
3... Warning lamp, 80... Normally closed relay.

Claims (1)

[Scope of utility model registration request] In an air conditioner for an automobile, a temperature fuse and a plurality of resistors are provided in series with a fan motor, and the rotation speed of the fan motor is adjusted by switching the plurality of resistors by a fan switch. What is claimed is: 1. A fuse blowout detection device for an automobile air conditioner, comprising a voltage detection circuit that outputs an output when the voltage across the series resistor and the series resistor is equal to or higher than a predetermined value.