JPS59176556A - Alarm device for overcharge of refrigerant - 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 The present invention relates to a device for preventing overfilling of a cooling cycle with a refrigerant used in a cooling cycle of an air conditioner for an automobile.

Generally, the cooling cycle for automobiles is as shown in Fig. 1.
A compressor 1, a condenser 2 that cools and condenses the gaseous refrigerant that has become high pressure and high temperature in the compressor 1 into a high pressure liquid, and a condenser 2 that stores the necessary refrigerant and converts the refrigerant. Liquid tank (liquid receiver) 3 for gas-liquid separation and removal of moisture and dust in the refrigerant to ensure smooth supply of refrigerant into the system, and a low-pressure refrigerant that rapidly depressurizes the refrigerant and easily vaporizes. It consists of an expansion valve 4 for cooling the air, and an evaporator 6 for cooling the air by removing heat from the air as the refrigerant evaporates.

In this automotive cooling cycle, there are large load fluctuations and the compressor is driven by the driving engine, so there are large changes in the amount of refrigerant circulated, so the cooling cycle operates smoothly in response to changes in the amount of refrigerant circulated. The amount of refrigerant required for this purpose is stored in the liquid tank 3, and the liquid tank 3 is provided so as to adjust the use of the circulating refrigerant as necessary. Here, if the amount of refrigerant is too small, the cooling capacity will decrease, which is undesirable, but if it is too large, the discharge pressure of the compressor 1 will increase, and the lubricating oil contained in the refrigerant will deteriorate due to the rise in refrigerant temperature. , it is required to enclose an appropriate amount.

Conventionally, there is a method for detecting the sealed state of the refrigerant by providing a side glass 7 at the refrigerant outlet of the liquid tank 3 and observing the flow state of the refrigerant.

According to this method, if bubbles are found in the refrigerant, it indicates a shortage of the refrigerant m. However, if there are no air bubbles, the amount of refrigerant filled in is not only appropriate (it is also considered to be in an overfilled state. Therefore, it is difficult to accurately grasp the overfilling of the refrigerant in the overfilled state section 15). There is also a method of detecting refrigerant overfilling using a high pressure switch that detects the pressure of the refrigerant on the high pressure side, but since it only senses the refrigerant pressure on the high pressure side, the rotation of the compressor +11 is difficult. Accurate detection is not possible due to fluctuations in load conditions.

The present invention has been made by paying attention to the fact that the subcool gap becomes large as a phenomenon when refrigerant is overfilled, and an object of the present invention is to provide an alarm device that detects the overfilled state of refrigerant. A working fluid with a higher evaporation pressure than the circulating refrigerant in the automobile cooling cycle is sealed in the sensor part 1], and the high-pressure side refrigerant of the circulating refrigerant is introduced around it to sense the amount of subcooling, and the pressure of the working fluid is lower than the refrigerant pressure. It is characterized by being comprised of a pressure switch that is activated when the pressure has decreased by a certain amount, and an alarm means that is controlled by this pressure switch.

The present invention will be described in detail below based on an embodiment shown in the drawings.

FIG. 4 schematically shows an embodiment of the refrigerant overfill alarm system according to the present invention. This overfill warning device was developed by paying attention to the fact that the amount of subcooling increases as a phenomenon when refrigerant is overfilled. and an alarm means 11 controlled by a pressure switch 10.

The pressure switch 10 is a diaphragm type differential pressure switch that seals a working fluid 13 with a higher evaporation pressure than the refrigerant 12 used in the cooling cycle in a sensor section 14 and detects the pressure difference between the working fluid 13 and the high-pressure refrigerant 12 introduced around it. A sensor,
Overfilling of the refrigerant 12 is detected using a reversal phenomenon in the pressure relationship between the refrigerant 12 and the working fluid (sealed fluid) 13 that occurs during excessive subcooling. In other words, if a fluid with a higher evaporation pressure than the refrigerant 12 is filled in the moving fluid 13 of the sensor section 14, the refrigerant on the high pressure side surrounding the sensor section 14 will be in a subcooled state, as shown in FIG. Although the temperature decreases under a constant pressure condition, the working fluid 13 undergoes a constant volume change due to the temperature change of the refrigerant 12, and the pressure decreases. For this reason, refrigerant 1
The pressure of 2 is lower than the pressure of the working fluid 13 immediately after crossing the saturated liquid line and finishing condensation, but as the subcooling progresses, the pressure of the working fluid 13 decreases by 1 along the saturated liquid line. Eventually, the pressure becomes higher than the pressure of the working fluid 13. Therefore, by arbitrarily setting the point at which this pressure relationship is reversed, the pressure switch 10 can be activated when a certain amount of subcooling is achieved. Here, the relationship between the subcooling state and refrigerant overfilling is clear from the Mollier diagram in Figure 3. When a certain amount of subcooling is used, the cooling capacity can be improved and there is no need to consider it as overfilling. If there is too much subcooling, both the high-pressure side pressure and the low-pressure side pressure will increase, making it difficult for the refrigerant to evaporate even after passing through the expansion valve 4.Question 4: This causes a problem peculiar to overfilling of the J5 subcooling section. This excessive subcooling state can be considered as overfilling of the refrigerant. Therefore, the sealed fluid 13 is selected and the evaporation pressure difference is determined so that the pressure switch 10 is activated when the amount exceeds a certain value. The subcool amount for estimating overfilling of the refrigerant varies depending on various conditions such as load conditions, but can be set to 5 degrees or more, for example.

The fluid 13 sealed in the sensor section 14 of this pressure switch 10 has a higher evaporation pressure with respect to temperature than the refrigerant 12 used. For example, the refrigerant 12 used is generally R12.
(Freon gas) is used, so nitrogen (N
) can be used to increase the pressure.

This pressure switch 10 has a cold high pressure side! Since the sub-cooling amount is detected based on the differential pressure between the pressure of the working fluid 13 and the pressure of the high-pressure refrigerant 12, which changes with the humidity change of 1112, and the electrical contacts are opened and closed, the high-pressure refrigerant flow path is particularly It is preferable to provide the refrigerant pipe 15 between the liquid tank 3 and the expansion valve 4. The pressure switch 10 includes a casing 16 that is fixed to the refrigerant pipe 15 in a liquid-tight manner, a sensor section 14 supported by the gauging 16 and partially protruding into the pipe 15 from the opening 17, and a sensor section 14 installed between these. It consists of switch terminals 18 and 19 which are connected to each other. The casing 16 is
A chamber for introducing the high-pressure side refrigerant exiting the liquid tank 3 is defined inside the chamber. Switch terminals 18 and 19 for opening and closing the electric circuit of the alarm means 11 are provided with a non-conducting sealing material 2.
The contact pieces 21 and 22 are fixed to the casing 16 and are opposed to each other. One side of this contact piece 2
1 is moved up and down by the diaphragm 23 of the sensor section 14 which is displaced by changes in the pressure of the working fluid 13, thereby opening or opening an electric circuit. Although a diaphragm type differential pressure sensor is employed as the sensor 9 part 14, this does not preclude the use of other pressure sensors or pressure switches such as a bellows type differential pressure sensor.

Alarm means 11 controlled by said pressure switch 10
Any means may be used as long as it appeals to the five senses of the worker, but methods that appeal to the auditory or visual sense, such as an alarm buzzer or an alarm lamp, are effective. This alarm means 11 is activated by an electric signal output by activation of the pressure switch 10.

As is clear from the above description, the refrigerant overfill warning device of the present invention includes a working fluid whose evaporation pressure is higher than that of the refrigerant circulating in an automobile cooling cycle, which is sealed in the refrigerant part.
It consists of a pressure switch that detects subcooling by introducing high-pressure side refrigerant of the circulating refrigerant around the refrigerant and operates when the pressure of the working fluid drops by a predetermined amount below the refrigerant pressure, and an alarm means controlled by this pressure switch. When the high-pressure refrigerant that has finished condensing begins to cool down below its saturation temperature, it enters the so-called sub-cooling state. The pressure relationship between the refrigerant and the working fluid is reversed when the refrigerant becomes overfilled, which occurs when both the high-pressure side pressure and low-pressure side pressure of the refrigerant are increased. Since the pressure switch is actuated by the pressure switch, the overfilling of the refrigerant is notified by the alarm means.In addition, this refrigerant overfill alarm device detects the pressure of the working fluid and the high pressure, which changes with the humidity change of the refrigerant on the high pressure side. Since it uses a pressure switch that is activated by reversing the differential pressure from the constant pressure of the side refrigerant, it is not affected by fluctuations in compressor rotation or load conditions.
Overfilling of refrigerant can be accurately detected. Therefore, the refrigerant filling operation can be carried out easily and accurately.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the principle of an automobile cooling cycle, and Figure 2 is a diagram showing the structure of a liquid tank.
b) is a plan view. FIG. 3 is a Mollier diagram comparing the cooling cycles when regular refrigerant is used and when refrigerant is overfilled. Fourth
The figure is a schematic diagram showing an embodiment of the refrigerant overfill warning device according to the present invention, and FIG. 5 is a diagram showing the relationship between the evaporation pressure and the temperature of the high-pressure side refrigerant and working fluid. 8- 10...Pressure switch, 11...Alarm means, 12
... Refrigerant, 13... Working fluid, 14...
・Sensor part. Patent applicant: Japan Radiator Co., Ltd. 10- Figure 2 (0)

Claims (1)

[Claims] UJ+ fluid, which has a higher evaporation pressure than the circulating refrigerant in the automobile refrigerant cycle, is sealed in the sensor section, and the high-pressure side refrigerant of the circulating refrigerant is introduced around the refrigerant to sense the leave cool and reduce the working fluid from the refrigerant pressure no. 1. A refrigerant overfill warning device comprising: a differential pressure switch that is activated when the pressure of the refrigerant decreases by a predetermined amount; and warning means controlled by the pressure switch.