JPH05180546A - Refrigerant sensor - Google Patents

Abstract

PURPOSE:To detect in an early time the tendency of decrease of the amount of filling of a refrigerant in a refrigerant sensor. CONSTITUTION:A refrigerant sensor 21 is comprised of a sensor body 22 including a refrigerant flow passage part 22A, a drawing part 22C, and a refrigerant chamber 25 formed on the upper side, and of a self-heating thermistor 26 disposed in the refrigerant chamber 25 of the sensor 22. In the case where a refrigerant F is of a proper amount of filling, a fluid level of the refrigerant F fills up the inside of the refrigerant flow passage part 22A and rises up to the inside of the refrigerant chamber 25 through the drawing part 22C to hereby dip the self-heating thermistor 26. In contrast, in the case where the refrigerant F tends to be decreased in the amount of filling, the fluid level of the refrigerant F in the refrigerant chamber 25 is lowered and hence the self-heating thermistor 26 is exposed. The fluid level of the refrigerant F is detected by cooling action of the self-heating thermistor 26 due to the refrigerant F.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant sensor suitable for use in, for example, an air conditioner for automobiles, and more particularly to a refrigerant sensor capable of detecting the filling amount of the refrigerant with high accuracy.

[0002]

2. Description of the Related Art Generally, an air conditioner is provided with a refrigerant sensor for determining whether or not the amount of refrigerant filled is appropriate in a cooling cycle. Then, the present inventor first found that
No. 576 (hereinafter referred to as "conventional technology") is provided with a stagnation part of the refrigerant in the flow path between the condenser and the evaporator that constitutes the cooling cycle, and a self-heating type temperature sensing element is provided in the stagnation part. A refrigerant sensor is proposed.

Here, an air conditioner using a refrigerant sensor according to the prior art is shown in FIGS. 2 and 3 and described.

In the figure, reference numeral 1 denotes a cooling cycle. The cooling cycle 1 has a pipe 2 which forms a circulation flow path for circulating a refrigerant F such as ammonia and chlorofluorocarbon, and a circulation direction of the refrigerant F in the middle of the pipe 2 ( It is composed of a compressor 3, a condenser 4 and an evaporator 5, which are sequentially provided along the direction of the arrow A in the figure), and the heat absorbing surface of the evaporator 5 is a driver's cab (not shown).
You will come inward. On the other hand, the compressor 3 is connected to the engine 6 via the electromagnetic clutch 7, and the engine 6
Is transmitted to the compressor 3.
Then, the refrigerant F is compressed by the compressor 3 and then, while passing through the condenser 4 and the evaporator 5, the high pressure gas is sequentially →
At the time of phase transition from high-pressure liquid to low-pressure gas, and at the time of phase transition from liquid to gas in the evaporator 5, heat is taken from the cab to cool the cab.

The compressor 3 is connected to the engine 6 via an electromagnetic clutch 7, and the electromagnetic clutch 7 transmits the rotation of the engine 6 to the compressor 3. The electromagnetic clutch 7 is connected by, for example, turning on an air conditioner switch (not shown), transmits the rotation of the engine 6 to the compressor 3, and drives the compressor 3.

A receiver tank 8 is provided between the condenser 4 and the evaporator 5 and is provided in the middle of the pipe 2 for temporarily storing the refrigerant F in a liquid state. A viewing window 8A is provided so that the liquefied state of the refrigerant F can be visually checked through the viewing window 8A.

Reference numeral 9 denotes an expansion valve which is provided between the receiver tank 8 and the evaporator 5 and which is provided in the middle of the pipe 2. The expansion valve 9 is constituted by a pressure reducing valve or the like.
Refrigerant F, which is discharged in a liquid phase state from, is depressurized to a predetermined pressure and circulated in the direction of arrow A. The refrigerant F decompressed by the expansion valve 9 evaporates while flowing through the evaporator 5, becomes a gas phase state, and is compressed again by the compressor 3.

Reference numeral 10 denotes a refrigerant sensor which is located between the receiver tank 8 and the expansion valve 9 and is provided in the middle of the pipe 2. The refrigerant sensor 10 has an outer shape as shown in FIG. It is composed of a main body casing 11 to be formed and a self-heating type thermistor 12 which will be described later and is provided in the main body casing 11.

Here, the main body casing 11 has a cylindrical refrigerant passage portion 11A forming a part of the pipe 2 and the refrigerant passage portion 11
It is composed of a bottomed cylindrical stagnation portion 11B which is located in the middle of A and projects downward. Both openings of the refrigerant passage portion 11A are connected to the pipe 2 and the stagnation portion 11B includes the refrigerant passage portion 1A.
A stagnation effect is given to the refrigerant F flowing in 1A in the direction of the arrow A, and the refrigerant F is temporarily accommodated.

Reference numeral 12 denotes a self-heating type thermistor as a self-heating type temperature sensitive element disposed on the bottom side of the stagnation portion 11B. The self-heating type thermistor 12 is a battery 13 as a power source as shown in FIG. The temperature is sensed at a predetermined temperature by the power supply from, and is constantly cooled by the refrigerant F in the stagnation portion 12B. Then, the self-heating type thermistor 1
2 indicates that the cooling amount changes depending on whether the refrigerant F in the stagnation part 12B is in the liquid phase state or the gas phase state, so that the self-heating temperature changes, and this temperature change is detected as a resistance value change. become.

Reference numeral 14 denotes an informing device connected in series with the battery 13 and the self-heating type thermistor 12. The informing device 14 includes a lamp 15, and the self-heating type thermistor 1 is provided.
When the resistance value of 2 is large, the lamp 15 is turned off, and when the resistance value is small, the lamp 15 is turned on.

In the refrigerant sensor 10 having the above-described structure, the refrigerant is in a gas phase state due to refrigerant leakage of the refrigerant F flowing in the direction of arrow A in the refrigerant passage portion 11A of the main body casing 11 or failure of the compressor 3. At this time, the self-heating temperature of the self-heating type thermistor 12 rises, the resistance value becomes small, and the current flowing from the battery 13 to the notification device 14 can be increased, whereby the lamp 15 is automatically turned on. The driver is informed that the cooling capacity has decreased.

Further, since the self-heating type thermistor 12 is provided in the stagnation part 11B, the liquid phase state and the gas phase state of the refrigerant F can be surely discriminated without being affected by the flow velocity of the refrigerant F. Therefore, the refrigerant state in the pipe 2 can be accurately detected.

[0014]

By the way, in the above-mentioned conventional refrigerant sensor, the main body casing 1 is used.
By providing the self-heating type thermistor 12 in the stagnation portion 11B of No. 1, the refrigerant state in the pipe 2 is detected, and the refrigerant F in the stagnation portion 11B is completely in the vapor phase state,
That is, it is detected that the refrigerant F in the pipe 2 (cooling cycle 1) is in a complete vapor phase state. As a result, according to the conventional technique, even if the amount of the refrigerant F in the cooling cycle 1 is substantially insufficient, the refrigerant shortage cannot be detected except in the case of the complete shortage. Therefore, there is a problem that the substantial tendency of the shortage of the refrigerant F cannot be detected early.

Further, in connection with the above problem, when it is detected that the refrigerant F is in the vapor phase state due to the change in the resistance value from the self-heating type thermistor 12, almost no refrigerant F is already present in the cooling cycle 1. Since it is in the open state, there is a problem that an accident such as seizure of the compressor 3 is likely to occur.

The present invention has been made in view of the above-mentioned problems of the refrigerant sensor according to the prior art, and an object of the present invention is to provide a refrigerant sensor capable of detecting a refrigerant shortage at an early stage.

[0017]

In order to solve the above-mentioned problems, the structure adopted by the present invention is a sensor main body having a refrigerant flow passage through which a refrigerant flows, It comprises a refrigerant chamber which is arranged on the upper side and communicates with the inside of the refrigerant flow path portion, and a temperature sensitive element which is provided in the refrigerant chamber and detects whether or not the refrigerant in the refrigerant chamber is in a liquid phase state.

[0018]

With the above structure, when the refrigerant charge amount is appropriate, the liquid level of the refrigerant reaches the refrigerant chamber, and when the refrigerant charge amount decreases, the liquid level drops from the refrigerant chamber. Based on the position of, the temperature sensitive element can detect the refrigerant leakage at an early stage.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In the embodiments, the same components as those of the conventional technique shown in FIG. 2 or FIG. 3 described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 21 denotes a refrigerant sensor according to this embodiment, which is arranged between the receiver tank 8 and the expansion valve 9 in place of the refrigerant sensor 10 of the prior art.

Reference numeral 22 denotes an outer shape of the refrigerant sensor 21, and indicates a sensor body 22 formed in a rectangular parallelepiped shape. The sensor body 22 is provided so as to penetrate from the left side surface to the right side surface in the drawing, and both ends are on the inner peripheral side. A refrigerant flow path portion 22A having internal thread portions 22A1 and 22A1, a large diameter hole 22B formed on the upper side of the refrigerant flow path portion 22A and having an internal thread portion 22B1 on the inner peripheral surface of the opening, and the large diameter hole 22B. It is generally composed of a bottom portion 22B2 of the diameter hole 22B and a small-diameter throttle portion 22C formed so as to communicate the refrigerant flow passage portion 22A.

Then, each female screw portion 2 of the refrigerant flow passage portion 22A.
A pipe 2 is screwed to 2A1 to allow the refrigerant F in the cooling cycle 1 to flow in the refrigerant flow passage portion 22A.

Reference numeral 23 denotes a lid body for covering the large-diameter hole 22B. The lid body 23 is formed in a cylindrical shape, a male screw portion 23A is formed on the outer peripheral surface on the upper end side, and an outer peripheral surface on the lower end side is formed. An annular O-ring groove 23B is formed. Also, the lid 2
3 has two lead wire insertion holes 23C, which are separated in the radial direction,
23C is drilled. Then, the O-ring 24 is inserted into the O-ring groove 23B and screwed into the large diameter hole 22B.

Reference numeral 25 denotes a lid 23 and a bottom portion 22 of the large diameter hole 22B.
B2 shows a refrigerant chamber formed between B2 and
Is formed by screwing the male thread portion 23A of the lid body 23 onto the female thread portion 22B1 of the sensor body 22, and communicates with the refrigerant flow passage portion 22A through the throttle portion 22C.

Reference numeral 26 denotes a self-heating type thermistor as a temperature sensing element disposed in the refrigerant chamber 25. The self-heating type thermistor 26 has lead wires 26A and 26A connected to the lid 23.
The lead wires 26A are attached to the lid 23 by inserting the lead wire insertion holes 23C into the lead wire insertion holes 23C via the stepped disc-shaped seal members 27, 27, and the lead wires 26A are led out to the outside of the refrigerant sensor 21, Connected to the notification device 14 described in the related art. The self-heating type thermistor 26 is positioned in the refrigerant chamber 25 at a predetermined height H from the bottom 22B2 of the large diameter hole 22B.

Here, the self-heating type thermistor 26 heats itself when an electric current is passed through each lead wire 26A and becomes high in temperature to lower the resistance value. Has a characteristic that the temperature decreases and the resistance increases.

The refrigerant sensor 21 according to this embodiment is constructed as described above. Next, the operation of detecting the refrigerant filling amount of the refrigerant sensor 21 will be described.

When the compressor 3 is operated by driving the air conditioner, the refrigerant F enters the liquid phase between the receiver tank 8 and the expansion valve 9, and when the refrigerant F is filled in the cooling cycle 1 in an appropriate amount. The liquid level of the refrigerant F fills the inside of the refrigerant flow path portion 22A and the refrigerant chamber 2 passes through the throttle portion 22C.
It goes up to the upper surface side in 5.

At this time, since the self-heating type thermistor 26 is immersed in the refrigerant F in the liquefied state, the cooling action of the refrigerant F is large, and the resistance value of the self-heating type thermistor 26 becomes large, so that the lamp 15 is turned off.

On the other hand, when the refrigerant F in the cooling cycle 1 decreases due to refrigerant leakage or the like, the liquid level of the refrigerant F in the refrigerant chamber 25 lowers so that the self-heating type thermistor 26 is exposed from the liquid surface of the refrigerant F. Become. Since the refrigerant F in the vapor phase has a smaller cooling effect than the refrigerant F in the liquid phase, the temperature of the self-heating type thermistor 26 rises, the resistance value becomes small, and the lamp 15 of the alarm device 14 lights up. Informs the driver that the refrigerant F is decreasing.

Thus, the self-heating type thermistor 26 is
The liquid level of the refrigerant F flowing into the refrigerant chamber 25 through the refrigerant flow path portion 22A and the throttle portion 22C is such that the self-heating type thermistor 26.
Since it is possible to detect whether or not the refrigerant is immersed, the refrigerant F
It is possible to detect a subtle decrease in the value with high accuracy.

Then, the driver selects the lamp 1 of the notification device 14.
It is possible to know the filling state of the refrigerant F by turning off and turning on 5.

Therefore, since the decreasing tendency of the refrigerant F, which cannot be detected early by the conventional refrigerant sensor, can be detected early, the no-load operation of the compressor 3 can be surely prevented. The compressor 3
It is possible to prevent the seizure and the like of the compressor and effectively protect the compressor 3.

The self-heating type thermistor 26 is provided in the refrigerant chamber 25 at a position of a predetermined height H. The height H depends on the arrangement of the refrigerant sensor 21 and the piping 2 of the cooling cycle 1. Since the setting can be appropriately made according to the handling relation and the like, it is possible to give a degree of freedom to the adjustment of the detection sensitivity of the refrigerant shortage.

In the above embodiment, the decrease tendency of the refrigerant F is performed by turning on the lamp 15 of the notification device 14, but the compressor 3 is stopped by a program connected to a control unit or the like, or the notification device is activated. It may be configured by a buzzer, voice synthesis, or the like, and notification may be given by a buzzer sound, voice, or the like.

[0036]

As described above in detail, according to the present invention, the sensor main body having the refrigerant flow passage through which the refrigerant flows, and the sensor main body disposed above the refrigerant flow passage, When the refrigerant is in the liquid phase state, it is composed of a refrigerant chamber communicating with the inside of the flow path section, and a temperature sensing element that is provided in the refrigerant chamber and detects whether the refrigerant in the refrigerant chamber is in the liquid phase state. Whether or not the amount of the refrigerant tends to decrease can be detected early from the height of the liquid surface, the detection accuracy can be improved, and a failure such as seizure of the compressor can be reliably prevented.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a refrigerant sensor according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an air conditioner according to the related art.

FIG. 3 is a vertical cross-sectional view of a refrigerant sensor according to the related art.

[Explanation of symbols]

 21 Refrigerant Sensor 22 Sensor Main Body 22A Refrigerant Flow Path 22B Large Diameter Hole 22C Throttle 23 Lid 25 Refrigerant Chamber 26 Self-heating Type Thermistor (Temperature Sensing Element) F Refrigerant H Specified Height

Claims (1)

[Claims] 1. A sensor main body having a refrigerant flow passage through which a refrigerant flows, a refrigerant chamber arranged above the refrigerant flow passage of the sensor main body and communicating with the inside of the refrigerant flow passage, and the refrigerant. A refrigerant sensor provided in a room, comprising a temperature sensitive element for detecting whether or not the refrigerant in the refrigerant room is in a liquid phase state.