JPS6229866A - Chilling unit for car - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle cooling system provided with a low-pressure cut switch.

(Prior art and its problems) Conventionally, in vehicle cooling systems, compressor failure occurs due to an abnormal drop in refrigerant pressure in the refrigeration cycle due to insufficient refrigerant amount due to refrigerant leakage or condensation of refrigerant in winter. In order to prevent accidents such as seizure, a low-pressure cut switch is installed that detects an abnormal drop in refrigerant pressure within the refrigeration cycle and disconnects the electromagnetic clutch that connects the compressor and engine, preventing the compressor from operating.

Normally, this low-pressure cut switch is set to operate at a pressure of 2.1 kg/cI (corresponding to the saturation temperature of the refrigerant, 0°C) or less, so the outside air When the temperature falls below 0° C., the cooling device will not operate due to the action of the low pressure cut switch.

However, when heating the vehicle interior in winter,
If the humidity is high, the window glass will fog up, which is not good for safe driving, but if the outside temperature is below 0°C, the electromagnetic clutch that operates the compressor will remain disengaged as described above, so dehumidification, which is an important function of the air conditioner, will not work. There was an inconvenience that the function could not be achieved and therefore it was not possible to dehumidify and remove the fog from the window glass.

(Objective of the Invention) The present invention was made in view of the above-mentioned problems, and it is an object of the present invention to provide a vehicle cooling device that operates even at low temperatures of 0° C. or lower and can exhibit its dehumidifying function. .

(Structure of the Invention) To achieve the above object, the present invention provides a vehicle cooling system equipped with a low pressure cut switch that detects a drop in refrigerant pressure and prevents the compressor from operating below a set pressure. Switch pressure setting value from 0.3 to 1.0
kg/cffl.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 is a schematic configuration diagram of a vehicle cooling system according to the present invention, in which a compressor 4 is connected to an output shaft 2 of a vehicle engine 1 via an electromagnetic clutch 3.
The discharge port of the compressor 4 is connected to the inlet of the condenser 6 via a conduit 5. The outlet of the condenser 6 is connected to the inlet of a liquid receiver 8 through a pipe 7, and the outlet of the liquid receiver 8 is connected to the inlet of an expansion valve 10 by a pipe 9. There is.

A low pressure cut switch 11, which will be described later, is installed in the pipe line 9 near the outlet of the liquid receiver 8. An outlet of the expansion valve 10 is connected to an inlet of an evaporator 13 via a pipe 12, and an outlet of the evaporator 13 is connected to an inlet of the compressor 4 via a pipe 14. . Note that 15 is a radiator, and 16 is a radiator fan. When the radiator fan 16 operates, air flows in as shown by the arrow, thereby cooling the condenser 6 and the radiator 15.

In this embodiment, the low voltage cut switch 11 has a voltage of 0.5
kg/a (and when the refrigerant pressure at the outlet of the liquid receiver 8 falls below this value when the cooling system is not in operation, the electromagnetic clutch 3 is turned off and the compressor 4 stops operating. The above setting value is 0.5 kg/cir.
In the case of R-12 (refrigerant type number) refrigerant, the equivalent saturation temperature is -20°C, so the low-pressure cut switch 11 does not operate at an outside temperature of -20°C, so the air conditioner can operate. It can exhibit dehumidification function.

Note that the practical range of the setting value of the low pressure cut switch 11 is
The range is 0.3 to 1.0 kg/cn! is suitable. The set value corresponds to the refrigerant saturation temperature of -24 to -13°C (R-42 refrigerant).

As mentioned above, the setting value of the low pressure cut switch 11 has been changed from the conventional setting value of 2.1 kg/cLa to 0.3 to 1.0 kg.
/d, the original function of the low voltage cut switch will not be impaired. That is, as shown in Fig. 2, when the outside temperature is 0°C, the amount of refrigerant remaining in the refrigeration cycle is at a pressure of 2.1 kg/an! In the case of 5%, the pressure is 0.3k
In the case of g/-, it decreases to 1 to 2%, but the operation of the compressor 4 in this state is because the temperature is low, the viscosity of the lubricating oil in the refrigerant is high, and it is not operated for a long time. Even with the above residual refrigerant amount, the compressor 4 will not seize.

In addition, the location where the low voltage cut switch 11 is installed is as follows:
Because it is necessary to sense the pressure at a location where there is the least thermal influence from other sources, that is, at a location closest to the outside air temperature, the pressure must be sensed at a location near the outflow port of the liquid receiver 8, such as piping in the inflow side air passage of the radiator, for example, as in the above embodiment. The pipe line 9 and the like are suitable.

(Effects of the Invention) As described above, the present invention provides a vehicle cooling system equipped with a low pressure cut switch that detects a drop in refrigerant pressure and prevents the compressor from operating below a set pressure. Pressure setting value of 0.3~1.0kg
/crA, the air conditioner can operate even when the outside air temperature is below 0°C, allowing the air conditioner to perform its dehumidifying function, which is an important function of the air conditioner.
Especially in winter, it is possible to prevent or remove fogging of window glass, which is suitable for safe driving.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a vehicle cooling system according to an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between refrigerant pressure and refrigerant gas amount in a refrigeration cycle. 4...Compressor, 11...Low pressure cut switch.

Claims (1)

[Claims] 1. In a vehicle cooling system equipped with a low pressure cut switch that detects a drop in refrigerant pressure and prevents the compressor from operating below a set pressure, the pressure set value of the low pressure cut switch is set to 0.3 to 1.0 kg/cm. A vehicle cooling device characterized by setting the temperature to ^2.