JPS5823245B2 - Cooler compressor protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooler compressor protection device, and more particularly to a cooler compressor protection device that detects refrigerant shortage and stops the operation of the cooler compressor.

Conventionally, this type of cooler compressor protection device was
As shown in FIG. 1, an ignition switch 6, a compressor switch 7 for operating a compressor 10 installed on an instrument panel (not shown), and a compressor switch 7 installed at a no-evaporator outlet (not shown) to detect the outlet temperature, a thermoswitch 8 that controls the operation of the compressor 10; and a low-pressure cut switch 3 that is installed between a liquid tank and an expansion valve (not shown) to detect refrigerant pressure, detect refrigerant shortage, and control the operation of the compressor 10. The compressor relay 2 may be connected in series between the power supply 9 and the electromagnetic clutch 1 of the compressor 10, or the compressor relay 2 may be connected in series between the ignition switch 6 and the electromagnetic clutch 1 as shown in FIG. A compressor switch 7, a thermoswitch 8, and a low pressure cut switch 3 are connected in series to the coil side of the compressor relay 2.

By the way, to explain the function of the low pressure cut switch 3, the low pressure cut switch 3 operates by detecting changes in refrigerant pressure, so when the outside temperature is high to a certain extent, the amount of refrigerant decreases. If even a small amount of liquid refrigerant remains in the cooling cycle, this low pressure cut switch 3 will detect the saturation pressure at that outside temperature, and the refrigerant will completely vaporize and reach the saturation pressure. The low pressure cut switch 3 will not be able to detect refrigerant leakage unless the pressure decreases to such an extent that the refrigerant leakage does not occur.

However, in reality, the refrigerant level decreases by about 20 to 40 coefficients, and even if some liquid refrigerant remains, a refrigerant shortage occurs, causing poor circulation of compressor oil due to insufficient cooling and refrigerant shortage, and the compressor 10 There may also be burn-in or abnormal noises.

Therefore, in order to detect even when a small amount of refrigerant has returned (liquid refrigerant remains during the cooling cycle) and stop the operation of the compressor 10, the set pressure of the low pressure cut switch 3 should be set higher. The pressure must be set at a high level, and the compressor 10 must be stopped by detecting a drop in refrigerant pressure within the 8-room cycle when the compressor is operating.

However, in the conventional cooler compressor protection device, if only the set pressure of the low pressure cut switch 3 is simply set to a high pressure, the outside air temperature will be 10 to 15%.
The low-pressure cut switch 3 is activated even at a temperature of about 30 degrees Fahrenheit, resulting in the inconvenience that the compressor 10 cannot be activated when it is desired to dehumidify the vehicle interior, and as a result, the set pressure cannot be increased. could not.

In view of the conventional cooler compressor protection device, the present invention sets the low pressure cut switch to a higher pressure, temporarily operates the compressor at the initial stage when the ignition switch and the compressor switch are closed, and reduces the refrigerant pressure. The cooler y is designed to raise the pressure and turn on the low pressure cut switch, and in the event of a refrigerant leak, detects a lack of pressure when the compressor is operating and stops the compressor in the event of a refrigerant leak, even if the amount of leakage is small.
The present invention provides a protection device for compressors.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

The cooler compressor protection device according to the first embodiment of the present invention shown in FIG. 3 is similar to the conventional protection device shown in FIG. switch 3
The electromagnetic clutch 1 of the compressor and the electromagnetic clutch 1 are connected in series, and the energization to the electromagnetic clutch 1 is directly controlled by the low pressure cut switch 3. A PTC ceramic resistor 4 (barium titanate Connect a positive temperature characteristic thermistor made from a ceramic semiconductor.

This PTC ceramic resistor 4 has an extremely small resistance value below a predetermined temperature, and when a current is passed through it, it self-heats, and when the predetermined temperature is reached, the resistance value rises rapidly, and the current is almost turned off! It is something that will not flow away.

Therefore, according to this first embodiment, when the ignition switch 6 is closed and the compressor switch T is closed, if the thermoswitch 8 installed in the evaporator (not shown) is closed, the current flows from the power source 9 to the ignition switch 6.
, compressor switch 1, thermo switch 8 and PT
It flows through the C ceramic resistor 4 and is supplied to the electromagnetic clutch 1, which operates the electromagnetic clutch 1 and the compressor 10 starts to operate.

From this state, the PTC ceramic resistor 4 self-heats, and when the PTC ceramic resistor 4 reaches a predetermined temperature (for example, 150 to 200 degrees Celsius) that it has as a characteristic, the PT
The resistance value of C ceramic resistor 4 increases rapidly, and this PT
Almost no current flows through the C ceramic resistor 4.

At this time, if a sufficient amount of refrigerant is sealed in the cooling cycle, the low pressure cut switch 3 connected in parallel with the PTC ceramic resistor 4 detects a pressure higher than its operating pressure and closes. Current flows from thermoswitch 8 through low pressure cut switch 3 to electromagnetic clutch 1, and compressor 10 continues its operation.

Also, if the refrigerant in the cooling cycle leaks and decreases, and the amount of refrigerant sealed is insufficient, the low pressure cut switch 3 connected in parallel with the PTC ceramic resistor 4 will detect the pressure below the operating pressure. It is open, no current is supplied to the electromagnetic clutch 1, and the compressor 10 stops its operation.

Next, according to the second embodiment shown in FIG. 4, a PT.
An outside temperature switch 5 is connected in series with the C ceramic resistor 4 to sense the outside temperature and to open when the temperature is below a predetermined temperature.

Therefore, according to the cooler compressor protection device of the second embodiment, when the outside temperature is low, the outside temperature switch 5 is open, and the energization to the electromagnetic clutch 1 can be reliably interrupted.

As mentioned above, in the cooler compressor protection device of the present invention, the PTC ceramic resistor is connected in parallel with the low voltage cut switch, so when the ignition switch or compressor switch is closed and the electromagnetic clutch is energized, the PTC ceramic resistor is connected in parallel with the low voltage cut switch. Current flows through the PTC ceramic low resistance side until it self-heats and its resistance value rises rapidly, and the compressor operates.

In this case, the low pressure cut switch closes, and even if the outside temperature is low (for example, about 10 to 15 degrees Celsius), the pressure of the refrigerant in the cooling cycle increases due to the operation of the compressor, and the low pressure cut switch is set. Even if the pressure is increased and the compressor is stopped by detecting a small decrease in refrigerant, as in the past, if the outside temperature is 10 to 15
The low pressure cut switch operates at temperatures around ℃ and the compressor does not stop working.

In this way, it is possible to detect a small decrease in refrigerant by increasing the set pressure of the low pressure cut switch and stop the compressor, completely preventing insufficient cooling, compressor seizure, or abnormal noise. This allows the compressor to be protected more reliably.

With this invention, the set pressure at which the low pressure cut switch operates when the compressor operates is now approximately 1 to 2 kg/c.
r? 900 for about 1G! , it did not work unless the refrigerant leaked, but the set pressure was changed to about 8 to 10 kq/cr.
It becomes possible to increase the temperature by increasing the a G value, and the operation of the compressor can be stopped due to leakage of refrigerant of about 20 to 40 degrees.

Father, as in the second embodiment above, by connecting the PTC ceramic resistor and the outside temperature switch in series, the compressor is activated when the outside temperature is low, such as below 0°C, and the compressor is activated during cranking or There is no need to apply extra load to the starter motor or engine during the initial stage of engine startup.

In each of the above embodiments, a case has been described in which the energization of the electromagnetic clutch of the cooler compressor is directly controlled by a low-pressure cut switch connected in series.However, as shown in Fig. 2, the case is controlled via a compressor relay. In addition, the present invention can be similarly applied to a cooler compressor protection device that uses a low-temperature cut switch to control energization to an electromagnetic clutch of a cooler compressor.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional cooler compressor protection device, Fig. 2 is a circuit diagram showing another conventional example, and Fig. 3 is a circuit diagram showing a cooler compressor protection device according to the first embodiment of the present invention. , FIG. 4 is a circuit diagram according to the second embodiment. 1...Electromagnetic clutch, 2...Compressor ring-1
3...Low voltage cut switch, 4...PTC ceramic resistor, 5...Outside temperature switch.

Claims (1)

[Claims] 1. The operating pressure of the low pressure cut switch 3 that controls the energization of the electromagnetic clutch 1 of the vehicle cooler compressor 10 is set to a high pressure, and the PTC is connected in parallel with the low pressure cut switch 3.
A cooler compressor protection device characterized by connecting a ceramic resistor 4. 2. Set the operating pressure of the low pressure cut switch 3 that stops energization of the electromagnetic clutch 1 of the vehicle cooler compressor 10 to a high pressure, and set the PT in parallel with the low pressure cut switch 3.
A cooler compressor protection device characterized in that a C ceramic resistor 4 is connected, and an outside temperature switch 5 is connected in series with the PTC ceramic resistor 4, so that when the outside temperature is low, power to the electromagnetic clutch 1 is cut off. .