JPH05231338A - Protecting device for air conditioenr of vehicle - Google Patents

Abstract

PURPOSE:To immediately detect the state that a compressor is left operated due to the breakdown and issue alarm by making a control unit recognize that a signal system becomes abnormal if it is detected that a compressor is operated when it is detected that an air conditioner ON signal is not output. CONSTITUTION:In order to turn on an electronic thermostat 5, the micro computer 21 of a control unit 23 gives high level signals to a transistor T from an output port Po to give the electronic thermostat 5 a low level air conditioner ON signal (a) to activate the thermostat 5. The micro computer 21 receives a compressor ON signal (b) from the electric supply line of a magnetic clutch 13 in a compressor 11. In addition, the compressor ON signal (b) is input in the input port of the micro computer 21 through an input port protective resister R2 after the adjustment of voltage level by a Zener diode ZD through a current limiting resister R1 and the elimination of noises by a capacitor C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner, and more particularly to an automatic air conditioner for a vehicle (hereinafter referred to as an auto air conditioner), which protects an air conditioner when a compressor non-stop condition occurs due to a failure. The present invention relates to a device for designing.

[0002]

2. Description of the Related Art In a conventional automatic air conditioner, as shown in FIG. 5, a control unit 3 mainly composed of a microcomputer 1 controls the on / off of an electronic thermostat 5. That is, when the control unit 3 determines that the electronic thermostat 5 should be turned on, the low-level air conditioner-on signal a is given to the electronic thermostat 5. As a result, the electronic thermostat 5 is activated and the air conditioner relay 9 is turned on / off according to the temperature detected by the evaporator temperature sensor 7, whereby the magnet clutch 13 for transmitting power to the compressor 11 is turned on. Is turned off, and as a result, the evaporator temperature is controlled to be substantially constant.

[0003]

In the above-mentioned conventional apparatus, the control unit 3 and the electronic thermostat 5 are provided.
When the wiring between the air conditioner and the electronic thermostat 5 and the wiring between the air conditioner relay 9 are short-circuited to the ground as shown by the broken line due to the cause of biting or the contacts of the air conditioner relay 9 are welded. , The magnetic clutch 13 is turned on and released, and the compressor 11
Is operated and released, and as a result, the evaporator may freeze and the compressor 11 or the evaporator may be damaged.

Accordingly, an object of the present invention is to provide a protective device for an air conditioner for a vehicle, which can immediately detect the compressor and warn the driver when the compressor is left operating due to the above-mentioned failure. To provide.

[0005]

In order to achieve the above object, the present invention provides a control unit for outputting an air conditioner on signal as necessary, and a compressor for a refrigerant circuit only when an air conditioner on signal is output. In a vehicle air conditioner having a signal system configured to be operable, means for detecting non-output of an air conditioner ON signal,
It is characterized by having means for detecting the operation of the compressor, and means for recognizing that the signal system is abnormal when the operation of the compressor is detected when the non-output of the air conditioner ON signal is detected. ..

[0006]

In the apparatus of the present invention, when the air conditioner on signal is not output, but the compressor is in the operating state, this is detected to recognize the abnormality. The anomaly may alert the driver of this, or
The compressor may be forcibly stopped.

[0007]

1 shows an embodiment of the present invention. In FIG. 1, the same elements as those in FIG. 5 already described are designated by the same reference numerals.

In the embodiment shown in FIG. 1, when the microcomputer 21 of the control unit 23 determines that the electronic thermostat 5 should be turned on, the microcomputer T supplies a high level signal from the output port P ₀ to the transistor T. A low-level air conditioner on signal a is given to the electronic thermostat 5 to operate it.
In addition, the microcomputer 21 connects the magnet clutch 13 to the power supply line of the magnet clutch 13.
Is supplied with power (that is, in the ON state), the compressor ON signal b indicating a high level is received. This compressor-on signal b passes through the current limiting resistor R ₁ and is adjusted by the Zener diode ZD to a voltage level suitable for the logic level of the microcomputer 21, and
After the noise is removed by the capacitor C, it is input to the input port P _1N of the microcomputer 21 through the input port protection resistor R ₂ .

The constructions of the electronic thermostat 5, the air conditioner relay 9, the magnet clutch 13 and the compressor 11 are the same as those of the conventional one already described.

FIG. 2 shows the microcomputer 21 of FIG.
The processing performed by is shown.

First, the logic level of the output port P ₀ for turning on / off the air conditioner on signal a is checked (step S ₁ ). If it is low level, it indicates that the air-conditioner on signal a is not output. At this time, next, the logic level of the input port P _1N to which the compressor ON signal b is applied is checked (steps S ₂ and S ₃ ). As a result, if the logic level of the input port P _1N is high, the magnet clutch 13
Is in the ON state, that is, the compressor 11 is operating. In that case, it is considered that there is some abnormality in the signal system from the controller 23 to the air conditioner relay 9, and the error flag is turned on (step S ₄ ).

When the error flag is turned on, the driver is warned of the occurrence of an abnormality by, for example, blinking a predetermined LED on the operation / display panel of the automatic air conditioner.
Alternatively, as shown in FIG. 3, the magnet clutch 13
Another relay 29 having a normally-closed contact inserted in the power supply line is provided in addition to the air conditioner relay 9, and the relay 29 is turned on by the control of the control unit 23 when the error flag is turned on. Alternatively, the power supply to the power supply may be stopped.

FIG. 4 shows another embodiment of the present invention.

This embodiment is different from the embodiment shown in FIG. 1 in that a compressor-on signal C is obtained from a signal line from an electronic thermostat 5 to an air conditioner relay 9 and led to a microcomputer 31. Is. In this case, when the compressor 11 is turned on, the compressor-on signal C indicates a low level, so this is converted into a high-level signal and the input port P of the microcomputer 31 is converted.
_In order to lead to _1N , the input port P _1N is pulled up to a high level and coupled to the compressor-on signal C through the sneak-proof diode D. The processing performed by the microcomputer 31 is almost the same as that described with reference to FIG.

The advantage of this embodiment is that the signal line for detecting the ON state of the compressor does not have to be drawn into the engine room. That is, since the air-conditioner relay 9 is normally located in the engine room, the signal line must be routed to the engine room in the embodiment of FIG. 1, but this is not necessary in this embodiment. However, in this embodiment, a defect due to an abnormality (for example, contact welding) of the air conditioner relay 9 cannot be detected.

As a modification of the embodiment shown in FIG. 4, as shown by a broken line in FIG.
It can also be introduced into the microcomputer 31 as an ON signal. This has the advantage of not requiring a special external connection to obtain the compressor on signal. In this case, the control unit 3
Only the abnormality of the signal wiring from 3 to the electronic thermostat 5 can be detected.

[0017]

As described above, according to the present invention,
It is possible to early remove the adverse effect on each part of the air-conditioning cycle, which is caused by the compressor being activated and released due to an abnormality in the signal system. Further, although the control unit normally uses a microcomputer, the present invention can be realized only by adding a simple input circuit thereto. Furthermore,
Recently, there are many systems in which an engine control computer is interposed between an electronic thermostat and an air conditioner relay. In such a system, the detection of the compressor operating state and the releasing state due to an abnormality of the engine control computer is also included in the present invention. It is possible.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a protection device according to the present invention.

FIG. 2 is a flowchart showing an abnormality detection process performed by the computer shown in FIG.

FIG. 3 is a circuit diagram showing an example for forcibly stopping the compressor when an abnormality is detected.

FIG. 4 is a circuit diagram showing another embodiment of the present invention.

FIG. 5 is a circuit diagram showing a conventional example.

[Explanation of symbols]

 5 Electronic thermostat 9 Air conditioner relay 11 Compressor 13 Magnet clutch 21,31 Microcomputer 23,33 Control unit

Claims (1)

[Claims] 1. A vehicle having a control unit that outputs an air-conditioner on signal as necessary, and a signal system configured to operate a compressor of a refrigerant circuit only when the air-conditioner on signal is output. In the air conditioner, means for detecting non-output of the air conditioner on signal, means for detecting operation of the compressor, and detection of non-output of the air conditioner on signal, when the operation of the compressor is detected, A protection device for a vehicle air conditioner, comprising: means for recognizing that the signal system is abnormal.