JPH04217765A - air conditioner - 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]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner suitably used as a cooling device for automobiles, and more particularly to an air conditioner in which the state of refrigerant in a flow path is detected by an optical refrigerant state detector. .

0002

[Prior Art] Generally, automobiles, houses, etc. have air conditioners,
It is equipped with an air conditioner such as a heating system to supply warm or cool air into the room.

FIGS. 4 to 6 show the case where a conventional air conditioner is used as a cooling device for an automobile.

In the figure, reference numeral 1 indicates a cooling cycle, and the cooling cycle 1 includes a pipe 2 forming a circulation passage in which a refrigerant F such as ammonia or Freon gas circulates, and a pipe 2 in the direction of circulation of the refrigerant F ( It consists of a compressor 3, a condenser 4, and an evaporator 5, which are arranged in sequence along the direction of arrow A in the figure, and the evaporator 5 has its endothermic surface facing into the operator's cab (not shown). It looks like this. After the refrigerant F is compressed by the compressor 3, it enters the condenser 4 and the evaporator 5.
While passing through the evaporator 5, the phase transition occurs sequentially from high pressure gas → high pressure liquid → low pressure gas, and when the phase transition from liquid to gas occurs in the evaporator 5, heat is removed from the driver's cabin to cool the inside of the driver's cabin. It looks like this.

A receiver tank 6 is located between the condenser 4 and the evaporator 5 and is provided in the middle of the pipe 2 to temporarily store the refrigerant F in a liquid state. A window 6A is provided through which the liquefaction status of the refrigerant F can be visually observed.

As shown in FIG. 5, the receiver tank 6 is connected to an inlet pipe 2A and an outlet pipe 2B that form part of the piping 2, and a dehumidifier 7 is disposed inside the receiver tank 6. Then, the receiver tank 6 introduces the gas-liquid mixed refrigerant from the condenser 4 through the introduction pipe 2A, and while dehumidifying the moisture in the refrigerant F with the dehumidifier 7, the refrigerant F in a liquid (liquid phase) state is made to flow in the direction of arrow A from the outlet pipe 2B toward the expansion valve 8, which will be described later.

Reference numeral 8 denotes an expansion valve located between the receiver tank 6 and the evaporator 5 and provided in the middle of the pipe 2. The expansion valve 8 is constituted by a pressure reducing valve, etc. The refrigerant F thus discharged is reduced in pressure to a predetermined pressure and is made to flow in the direction of arrow A. And the expansion valve 8
The refrigerant F, whose pressure has been reduced in pressure, evaporates while flowing through the evaporator 5, becomes a gaseous state, and is compressed again by the compressor 3.

Reference numeral 9 indicates a flow sensor as a refrigerant state detector located between the receiver tank 6 and the expansion valve 8 and provided in the middle of the outlet pipe 2B of the piping 2.
As shown in FIG. 5, the refrigerant F is composed of an optical detector consisting of a light emitting element 9A and a light receiving element 9B, which are disposed facing each other in the middle of the outlet pipe 2B, and the refrigerant F flowing in the direction of arrow A in the outlet pipe 2B. It is designed to detect whether or not it is in a liquid phase state.

That is, since the refrigerant F in the liquid phase has high light transmittance, the light receiving element 9B of the flow sensor 9 is similar to the light emitting element 9.
The flow sensor 9 receives the light from A through the refrigerant F.
The detection voltage V as a detection signal from the oscillator is at a higher level than the predetermined voltage Vi shown in FIG. On the other hand, when the refrigerant F in the pipe 2 leaks to the outside and becomes insufficient, the refrigerant F in a gas-liquid mixed state flows through the outlet pipe 2B, reducing the light transmittance. As a result, the amount of light received by the light receiving element 9B of the flow sensor 9 decreases, and the detected voltage V reaches the predetermined voltage Vi.
It will be lower than that.

Reference numeral 10 indicates a control circuit that lights up a warning lamp 11 when there is a refrigerant shortage.The control circuit 10 has an input side connected to the flow sensor 9 and an output side connected to the warning lamp 11. When the refrigerant F in the pipe 2 becomes insufficient due to a leakage accident, the control circuit 10 controls the flow sensor 9
Since the detected voltage V from the pipe 2 falls below the predetermined voltage Vi, the warning lamp 11 is turned on based on this to warn the driver of the car that the refrigerant F in the pipe 2 is insufficient. ing.

In the conventional technology configured as described above, for example, when the cooling cycle 1 is installed in an automobile, a refrigerant F such as Freon gas containing lubricating oil is filled into the pipe 2, and the air conditioner switch (not shown) is turned on. The cooling cycle 1 is operated by turning on the air conditioner. Thereby, the compressor 3 is driven by rotational output from an engine (not shown), and compresses the refrigerant F in the pipe 2 while causing it to flow in the direction of the arrow A.

While flowing through the condenser 4, this refrigerant F is condensed into a gas-liquid mixed state, separated into gas and liquid in the receiver tank 6, and the refrigerant F in the liquid phase is passed through the expansion valve 8. The air flows into the evaporator 5, and while it evaporates (vaporizes) in the evaporator 5, it cools the inside of the driver's cabin while removing heat from the inside of the driver's cabin, becomes a gas phase, and is again compressed by the compressor 3.

On the other hand, the flow sensor 9 is connected to the receiver tank 6.
It is detected whether or not the refrigerant F derived from the refrigerant is in a liquid phase state, and this refrigerant F becomes a gas-liquid mixed state, bubbles are generated in this refrigerant F, and the amount of light received by the light receiving element 9B decreases. When this occurs, the detected voltage V falls below the predetermined voltage Vi, so the control circuit 10 determines that a refrigerant shortage has occurred due to a refrigerant F leakage accident, etc., and warns the driver of the refrigerant shortage by lighting the alarm lamp 11. do.

[0014]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, when the piping 2 is filled with a refrigerant F such as Freon gas containing lubricating oil and the cooling cycle 1 is operated, the temperature of the refrigerant F changes. Depending on the situation, the lubricating oil may separate from the refrigerant F, and an undissolved area of the lubricating oil may become cloudy in the refrigerant F flowing through the pipe 2, causing the flow sensor 9
The amount of light received by the light-receiving element 9B decreases due to this clouding, and the detection voltage V changes as shown in the characteristic line shown in FIG.
The voltage Vi falls below the predetermined voltage Vi for a relatively short period of time.

For this reason, in the prior art, when the optical flow sensor 9 detects a refrigerant shortage, the detection voltage V from the flow sensor 9 drops below the predetermined voltage Vi even when the refrigerant F becomes cloudy, causing an alarm. The lamp 11 may light up, and there is a problem in that it is not possible to determine whether this is due to refrigerant leakage or clouding.

The present invention has been developed in view of the problems of the prior art described above, and the present invention can distinguish between refrigerant leaks and cloudy conditions, and can detect refrigerant shortages due to refrigerant leaks with high accuracy, thereby improving reliability. The purpose of the present invention is to provide an air conditioner that can improve the

[0017]

[Means for Solving the Problems] A feature of the configuration adopted by the present invention in order to solve the above-mentioned problems is a level determination that determines whether a detection signal from a refrigerant state detector has fallen below a predetermined level. and a counting means for counting the duration of the decreased state when the level determining means determines that the detection signal has decreased below a predetermined level;
The present invention further includes a refrigerant shortage determining means for determining whether or not there is a shortage of refrigerant in the flow path based on the duration counted by the counting means.

[0018]

[Operation] With the above configuration, when the detection signal from the refrigerant condition detector continues to drop below a predetermined level for a certain duration, it can be determined that the refrigerant in the pipe is insufficient due to a leakage accident, etc. If the duration is short, it can be determined that it is due to clouding.

[0019]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3. In the embodiment, the same components as those of the prior art shown in FIGS. 4 to 6 described above are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, 21 is an air conditioner switch that is manually operated by the driver of a car when the cooling cycle 1 is in operation, and 22 is an air conditioner switch that is located between the receiver tank 6 and the expansion valve 8 and is provided in the middle of the pipe 2. As shown in FIG. 2, the flow sensor 22 is connected in the middle of the pipe 2 and is connected to a cylindrical casing 23 that forms part of the flow path of the refrigerant F. , a light emitting element 27, a light receiving element 28, etc., which will be described later.
A protrudes outward in the radial direction. The casing 23 also has radial through holes 23B, 23B that communicate with the inside of the casing 23 coaxially with each mounting portion 23A, and radially located on the outside of each of the through holes 23B on the bottom side of each mounting portion 23A. Annular seal grooves 23C, 23C are provided.

24, 24 are respective mounting portions 2 of the casing 23
3A is shown, and each element holder 2 is shown
4 is formed into a cylindrical shape from a metal material, and a male threaded portion 24A that is screwed into the mounting portion 23A is formed on the outer periphery of the distal end thereof. An annular step portion 24B is formed on the proximal side of the inner peripheral side of each element holder 24, and each step portion 24B
The light emitting element 27 and the light receiving element 28 are positioned within each element holder 24.

25, 25 are respective mounting portions 2 of the casing 23
3A through O-rings 26, 26, each sight glass 25 is formed into a thick disk shape from a transparent glass material or the like, and each element holder 24
and the casing 23 with each O-ring 26 interposed therebetween.

Furthermore, each O-ring 26 is connected to the casing 23.
The refrigerant F flowing in the direction of arrow A in the casing 23 is prevented from leaking to the outside from each through hole 23B by sealing between the casing 23 and each sight glass 25. is prevented.

27 and 28 are inserted into each element holder 24, and cylindrical mounting bolts 29 and 2 are inserted into each element holder 24.
9 shows a light emitting element and a light receiving element constituting a light emitting part and a light receiving part which are fixed through an annular collar part 27A, 28A and a terminal pin 27.
B, 27B, 28B, 28B, and collar portions 27A, 28
A indicates each mounting bolt 29 on the inner periphery of the base end of each element holder 24.
By screwing them together, they are held between the tip end surface of each mounting bolt 29 and the stepped portion 24B of each element holder 24.

[0025]The light emitting element 27 and the light receiving element 2
8, each element holder 2 is attached to each mounting portion 23A of the casing 23.
4, and are arranged opposite to each other in the diametrical direction of the casing 23 with each sight glass 25 interposed therebetween.

[0026] Thus, the flow sensor 22
When the light receiving element 28 receives the light from the casing 23, the detection voltage V as a detection signal corresponding to the state of the refrigerant F flowing in the direction of the arrow A in the casing 23 is almost the same as that of the flow sensor 9 described in the prior art. It is designed to output in the same way.

Further, 30 indicates a control unit constituted by a microcomputer or the like, and the input side of the control unit 30 is connected to the air conditioner switch 21.
, the flow sensor 22, etc., and the output side is connected to the compressor 3, the alarm lamp 11, etc. The control unit 30 has a storage circuit in its memory circuit as shown in FIG.
The program stored therein is configured to perform refrigerant state determination processing and the like to determine whether or not the refrigerant F flowing through the pipe 2 is insufficient. The memory circuit of the control unit 30 also stores a predetermined voltage Vi for determining whether the detected voltage V from the flow sensor 22 has decreased below a predetermined level, and a duration T in a memory area 30A.
A timer for counting and a predetermined time Tm (Tm>Ti) longer than the time Ti during which the detected voltage V from the flow sensor 22 decreases due to clouding are stored.

The air conditioner according to this embodiment has the above-described configuration, and its basic operation is not particularly different from that of the prior art.

The refrigerant state determination processing and the like by the control unit 30 will be explained with reference to FIG. 3.

First, when the air conditioner switch 21 is turned on, the compressor 3 is activated and the processing operation is started. In step 1, the timer is reset to zero (T=O) and stopped. Then, in step 2, a detection voltage V corresponding to the state of the refrigerant F flowing in the pipe 2 from the flow sensor 22 is detected.
is read, and in step 3, this detected voltage V is set to a predetermined voltage Vi
If it is determined as YES, the detected voltage V is high and there is an appropriate amount of refrigerant F in the pipe 2.
Since it can be determined that the battery is filled, the process returns to step 1 and the subsequent processes are continued.

Furthermore, when the determination in step 3 is "NO", the detected voltage V has decreased below the predetermined voltage Vi, so the process moves to step 4, where the timer is activated and the detected voltage V has decreased below the predetermined voltage Vi. Count the duration T that continues. Then, in step 5, it is determined whether or not this duration time T is longer than the predetermined time Tm. If the determination is "NO", the process moves to step 6, reads the detected voltage V from the flow sensor 22 again, and returns to step 3. to continue processing.

As a result, when the detected voltage V decreases due to cloudiness of the refrigerant F, the duration T becomes the time Ti (T
i < Tm ), and the detected voltage V rises again before the predetermined time Tm is exceeded (see Figure 6), and it is determined as "YES" in step 3, so the timer is reset to zero in step 1, and the duration is It is stopped by setting T to T=0.

Furthermore, when the determination is ``YES'' in step 5, the duration T exceeds the predetermined time Tm and the detected voltage V continues to decrease, indicating that the refrigerant F in the pipe 2 is insufficient due to a leakage accident, etc. It is determined that there is a refrigerant, and the process moves to step 7, where the warning lamp 11 is turned on to notify the driver of refrigerant shortage (refrigerant leak), and the compressor 3 is stopped.

Thus, according to this embodiment, when the detected voltage V from the flow sensor 22 drops below the predetermined voltage Vi, it can be determined whether the cause is cloudiness of the refrigerant F by counting the duration T. It is possible to determine whether the problem is caused by a refrigerant leak, and in the event of a refrigerant leak, the alarm lamp 11 is lit to immediately notify the driver of this, thereby improving the detection accuracy in the event of a refrigerant leak.

Furthermore, since the compressor 3 is stopped in the event of a refrigerant leak, it is possible to prevent the compressor 3 from continuing to operate for a long time, and it is possible to protect the compressor 3 by suppressing the occurrence of seizures and the like.

Therefore, according to this embodiment, it is possible to reliably prevent erroneous detection as a refrigerant leak when the refrigerant F filled in the pipe 2 becomes cloudy, improve the detection accuracy in the event of a refrigerant leak, and increase reliability. In addition, various effects can be achieved, such as the ability to protect the compressor 3 in the event of refrigerant leakage.

In the above embodiment, in the program shown in FIG. 3, step 3 shows a specific example of the level determining means which is a component of the present invention, and step 5 shows a specific example of the refrigerant shortage determining means. There is.

Furthermore, in the above embodiment, the flow sensor 22
Although the casing 23 has been described as being formed separately from the pipe 2, instead of this, the casing 23 is formed integrally with the pipe 2, and corresponds to each mounting portion 23A, each through hole 23B, and each seal groove 23C. The portion may be provided in the piping 2 in advance.

Further, in the embodiment described above, the alarm lamp 11 is lit to notify the driver when a refrigerant leaks, but instead of this, an alarm buzzer, a voice synthesizer, etc. may be used to detect the refrigerant. It may also be possible to notify when there is a leak.

[0040]

As described in detail above, according to the present invention, when the detection signal from the refrigerant condition detector falls below a predetermined level, the duration of this condition is counted, and the flow path is adjusted based on this duration. Since the structure is configured to determine whether or not there is a shortage of refrigerant in the flow path, for example, even if an undissolved region of lubricating oil becomes cloudy in the refrigerant flowing inside the flow path, this cloudiness will prevent the refrigerant from leaking. Various effects can be achieved, such as preventing erroneous detection, detecting refrigerant leaks with high accuracy, and improving reliability.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram showing an embodiment of the present invention.

FIG. 2 is a longitudinal cross-sectional view showing a flow sensor.

FIG. 3 is a flowchart showing refrigerant state determination processing and the like.

FIG. 4 is a circuit diagram showing a cooling device according to the prior art.

FIG. 5 is an explanatory diagram showing a receiver tank and the like.

FIG. 6 is a characteristic diagram showing detection voltage of a flow sensor.

[Explanation of symbols]

1 Cooling cycle 2 Piping 3 Compressor 4 Condenser 5 Evaporator 6 Receiver tank 8 Expansion valve 11 Alarm lamp 22 Flow sensor (refrigerant condition detector) 23 Casing 24 Element holder 25 Sight glass 27 Light emitting element (light emitting part) 28 Light receiving element ( Light receiving part) 30 Control unit F Refrigerant

Claims (1)

[Claims] 1. A flow path in which a refrigerant circulates, a condenser and an evaporator provided in the middle of the piping forming the flow path, and a condenser and an evaporator located between the condenser and the evaporator of the piping. A compressor is provided in the middle of the flow path to compress the refrigerant in the pipe, and the refrigerant compressed by the compressor is in a liquid phase, and the light from the light emitting part is received by the light receiving part. In an air conditioner comprising an optical refrigerant state detector for detecting the refrigerant state in the flow path, a level determining means for determining whether a detection signal from the refrigerant state detector has decreased below a predetermined level; , a counting means for counting the duration of this reduced state when the level determining means determines that the detection signal has decreased below a predetermined level; An air conditioner comprising: refrigerant shortage determination means for determining whether or not there is a shortage of refrigerant.