JPS6089656A - Alarm device for over-filling of refrigerant of air cooling cycle - 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 (Technical Field) The present invention relates to a device that detects overfilling of a refrigerant circulating in a cooling cycle of an automobile air conditioner and performs necessary processing such as issuing a warning.

(Technology backstory) Air conditioning for automobiles in general! As a cooling cycle system for
There is something like the one shown in Figure 1. A refrigerant circulates within the cooling cycle, and the cooling cycle includes a compressor 1, a condenser 2 that cools and condenses the gaseous refrigerant that has become high temperature and high pressure in the compressor 1, and converts it into a high pressure liquid. A liquid tank 3 stores a required amount of refrigerant, removes moisture and dust from the refrigerant, and separates the refrigerant into gas and liquid.The temperature of the refrigerant at the outlet of the evaporator 6 is sensed and the opening degree of the expansion valve 4 is adjusted. It has a temperature-sensitive cylinder 5, an expansion valve 4 for rapidly reducing the pressure of the liquid refrigerant to become a low-pressure, easily vaporized refrigerant, and a fan (not shown) to introduce the refrigerant into the device while it evaporates. and an evaporator 6 that removes heat from the air and cools the interior of the vehicle. Although not shown, the compressor 1 is driven by the driving engine via a magnetic clutch 8, and when the temperature of the interior of the vehicle, the surface of the evaporator, or the passing air becomes below a certain humidity, the compressor is activated by the action of the magnetic clutch. The function of the evaporator is stopped to prevent the interior of the vehicle from becoming too cold or the evaporator to freeze.

(Problems with the prior art) In this type of automotive cooling cycle, the compressor is driven by the driving engine, so the compressor drive rotation speed varies depending on the driving condition, and the amount and pressure of refrigerant circulating in the cooling cycle vary. may change.

Fluctuations in the amount of refrigerant circulated are alleviated to some extent because the liquid tank 3 adjusts the amount of refrigerant circulated as necessary. However, if the cooling cycle is not filled with an appropriate amount of refrigerant, even if there is a liquid tank, it is not possible to circulate the appropriate amount of refrigerant within the cycle. In particular, when the refrigerant is overfilled in the cycle, the liquid tank becomes full of liquid refrigerant, and subcooling (supercooling) of the refrigerant develops even within the liquid tank, and the refrigerant continues to flow through the expansion valve 4. This makes it difficult for the refrigerant to evaporate, and the heat absorption of the refrigerant in the evaporator becomes insufficient, resulting in problems such as a drop in cooling performance.

In order to eliminate these inconveniences in advance, conventionally, as shown in Fig. 2, a sight glass 7 is installed on the upper part of the liquid tank 3, and the flow state of the refrigerant is observed through the sight glass 7 to determine the amount of refrigerant. Excess and deficiencies are detected and the appropriate refrigerant is filled. In this case, when bubbles are seen in the refrigerant through the sight glass 7, it indicates that the amount of refrigerant is insufficient, and when there are no bubbles, it indicates that the amount of refrigerant is appropriate. However, if no air bubbles are seen in the refrigerant, it is not only possible that the amount of refrigerant charged is appropriate, but also that the refrigerant is overfilled, so it is difficult to accurately determine whether the refrigerant is overfilled. Met.

(Object of the Invention) The present invention has been made in view of the above circumstances, and provides a device that can detect overfilling of refrigerant that degrades cooling performance and take necessary measures such as issuing an alarm. The purpose is to provide

(Structure of the Invention) A feature of the present invention is that a working fluid is sealed inside the high-pressure side refrigerant passage in the cooling cycle, and the operation is performed by the pressure difference between the pressure of the working fluid and the refrigerant. A sensor having a movable part is attached, a switch interlocked with the movable part and an alarm means are electrically connected, and a fluid having saturation pressure characteristics substantially the same as the saturation pressure of the refrigerant is sealed in the sensor part as the working fluid. , the working fluid is always saturated within the operating temperature range of the refrigerant, the subcooling temperature of the refrigerant exceeds a predetermined value, and the pressure of the refrigerant is higher than the pressure of the working fluid by a predetermined value or more. The point is that the switch is actuated when the situation occurs.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 3 is a schematic diagram showing an embodiment of a refrigerant overfill warning device for a cooling cycle according to the present invention.

The refrigerant pipe 15 shown in FIG. 3 does not show a part of the refrigerant pipe provided between the condenser 2 and the expansion valve 4 in FIG. 1, and a high-pressure liquid refrigerant 12 is guided therein. It is circulating. A casing 16 having a space communicating with the inside of the refrigerant pipe 15 through an opening 17 formed in the refrigerant pipe 15 is attached to the refrigerant pipe 15.The casing 16 has a small-diameter tip that reaches into the inside of the refrigerant pipe 15. A sensor 14 consisting of a large diameter section located within the rung 16 is attached.

The sensor 14 has a working fluid 13 sealed therein, and has a diaphragm 23 as a movable part that is actuated by a pressure difference between the pressure of the working fluid 13 and the pressure of the refrigerant 12. A switch 10 consisting of a fixed contact piece 19 attached to the casing 16 C and having a switch terminal 22, and a movable contact piece 21 attached to the casing 16 C and having a switch terminal 18 and interlocked with a diaphragm 23 is connected to the alarm means 11. electrically connected.

Note that the distance between the switch terminals 18.22 is variable using an adjustment screw 24 installed in the casing 16, and the switch terminals 18.22 are brought into contact with each other and the alarm means 1
The position at which the first circuit is turned on can be adjusted. In other words, the adjusting screw 24 can adjust the pressure difference between the working fluid 13 and the refrigerant 12 that switches on the alarm circuit 11 .

The working fluid 13 sealed in the senna 14 may be any fluid as long as it has saturation pressure characteristics that are approximately the same as the saturation pressure of the refrigerant 12, but it is preferable to use the same fluid as the refrigerant. It is the simplest.

Fi amount of the same fluid as the refrigerant 12 is sealed in the sensor 14 as a working fluid 13, and the working fluid 13 is always in a saturated state (liquid phase and gas phase are kept in equilibrium) within the operating temperature range of the refrigerant 12. Working fluid 13 and cold W when in state):
The temperature and pressure relationship with 12 is shown in FIG. The vertical axis is pressure P, and the horizontal axis is temperature T. Symbol F indicates a saturated liquid line of the refrigerant 12 and the working fluid 13. Since an appropriate amount of the working fluid 13 is sealed in the sensor 14, the saturated liquid line F is always maintained.
Try to move the above state (for example, from curve E' to G).

Further, since the refrigerant 12 may be in a subcooled state, it may deviate from the saturated liquid line F and change its state as shown by the straight line E'→A'.

Next, the operation will be explained.

FIG. 5 shows the cooling cycle shown in FIG. 1 on a Mollier diagram, where the vertical axis shows pressure P and the horizontal axis shows enthalpy i. In the figure, the symbol F indicates a saturated liquid line of the refrigerant 12, and the symbol G indicates a saturated vapor line of the refrigerant 12. Also, one cycle of the cooling cycle is the line A-+F34C-D→E→A
Or, it is indicated by the dashed dotted line A'→B'→C'→C'→E'→A', which respectively indicates one cycle when the normal amount of refrigerant is filled and one cycle when the refrigerant is overfilled. The straight line @D→[→A and the dashed dot line D'→E'→A' indicate the state from the discharge port of the compressuna 1 to the expansion valve 4, and the straight line E-)A and the dashed dotted line E'→A' indicate the refrigerant Indicates subcooling (supercooling). The subcooling amount when the normal amount of refrigerant is filled in the cooling cycle corresponds to E-+A.

However, when the refrigerant is overfilled, the pressure of the refrigerant increases and the liquid tank 3 becomes full of liquid refrigerant, and subcooling develops in the liquid tank 3 as well, and the amount of subcooling increases as shown in Fig. 5. To increase. State change of subcooled state of refrigerant 12 when subcooling increases E'→A
' corresponds to the straight line E'→A' shown in FIG. As shown in FIG. 3, the working fluid 13 and the refrigerant 12 undergo the same temperature change because the cold 112 is conducted around the working fluid 13. As shown in FIG. ′→Δ′
When the state changes, the state of the working fluid 13 changes from E' to G, and the pressure of the working fluid 13 becomes lower than the pressure of the refrigerant 12.

In other words, if the cooling cycle is overfilled with refrigerant, the subcooling will increase and the piping 1 between the condenser 2 and the expansion valve 4 will
The pressure of the working fluid 13 in the sensor 14 provided at 5 is:
The pressure will be lower than the pressure of the cold ts12 surrounding the sensor 14.

In this way, the pressure of the working fluid 13 in the sensor 14 is
When the pressure becomes lower than 2, the force of the pressure difference acts on the diaphragm 23, pushing the diaphragm down. When the amount of depression exceeds a predetermined interval adjusted by the adjustment screw 24, the circuit having the alarm means 11 is switched on.
By the function of the alarm means 11, it is possible to notify the worker who is filling the refrigerant or the driver of the vehicle of the overfilling of the refrigerant.

The types of cold W'' 12 and working fluid 13 used in the above-described embodiments are usually R12 (fluorocarbon gas) or the like.

Furthermore, the present invention is not limited to the above-described embodiments, and may include the following modifications.

Instead of the diaphragm 23 in the casing 16, the upper part of the sensor may be formed into a bellows shape, and the bellows may move up and down due to the differential pressure between the inside and outside of the sensor. Even in this case, the same effect as when using the diaphragm 23 is obtained.

Further, the warning means may be any means as long as it appeals to the five senses of the operator or driver, such as a warning buzzer or a warning lamp.

(Effects of the Invention) As is clear from the above description, according to the present invention, it is possible to detect overfilling of refrigerant in the cooling cycle, which reduces cooling performance, and to enable workers and automobiles to perform refrigerant filling work. Since a warning can be issued to the driver of the vehicle, the cooling cycle can always be operated in a normal state with good cooling performance.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of an automobile cooling cycle, Fig. 2 is a vertical sectional view showing the structure of a liquid tank, and Fig. 3 is a schematic diagram showing an embodiment of the refrigerant overfill warning device for a cooling cycle according to the present invention. , FIG. 4 is a diagram showing the relationship between pressure and concentration of circulating refrigerant and working fluid, and FIG. 5 is a diagram showing the cooling cycle on a Mollier diagram. 10...Switch, 11...Alarm means, 12...
Refrigerant, 13... Working fluid, 14... Sensor.

Claims (1)

[Claims] A sensor is installed in the high-pressure side refrigerant passage in the cooling cycle, which has a working fluid sealed therein and has a movable part that is activated by a pressure difference between the pressure of the working fluid and the refrigerant;
electrically connecting a switch interlocked with the movable part and an alarm means;
A fluid having saturation pressure characteristics substantially the same as the saturation pressure of the refrigerant is sealed as the working fluid in the sensor section, and the working fluid is always in a saturated state within the operating temperature range of the refrigerant, and the subcooling of the refrigerant is maintained. When the amount exceeds a predetermined value,
A refrigerant overfill warning device for a cooling cycle, characterized in that the switch is activated when the pressure of the refrigerant becomes higher than the pressure of the working fluid by a predetermined value or more.