JPH04222367A - Air conditioning apparatus - Google Patents

Abstract

PURPOSE:To detect proper timing of filling of refrigerant correctly by a method wherein a reference value (voltage) for deciding the proper filling according to the temperature of the refrigerant, filled into a piping, is set variably in an air conditioning apparatus equipped with an optical refrigerant condition detector. CONSTITUTION:A filler 21 for filling refrigerant into a piping 2, in which the refrigerant F is circulated, is connected while a temperature sensor 23, detecting the temperature(t) of the filling refrigerant, is provided. A reference value Vi for deciding proper filling based on the signal of the temperature sensor 23 is set variably and the reference value Vi is compared with the detecting voltage V of a flow sensor. When the temperature(t) of the filling refrigerant is high, for example, the reference value Vi is reduced to decide proper filling and, therefore, overfilling of the refrigerant can be prevented and proper filling timing can be detected correctly.

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 system for automobiles, and more particularly to an air conditioner equipped with an optical refrigerant state detector for detecting the state of refrigerant in a flow path.

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.

[0003] Here, FIGS. 5 to 7 show a cooling device for an automobile as a conventional air conditioner and will be described.

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. On the other hand, compressor 3
is driven by the rotational output of an engine (not shown). After being compressed by the compressor 3, the refrigerant F passes through the condenser 4 and the evaporator 5, and undergoes a phase transition from high-pressure gas to high-pressure liquid to low-pressure gas, and in the evaporator 5, the liquid changes to gas. When the phase transition occurs, heat is removed from the inside of the driver's cab to cool the inside of the driver's cabin.

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. 6, the receiver tank 6 is connected to an inlet pipe 2A and an outlet pipe 2B which form part of the piping 2, and a dehumidifier 9 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 an optical 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, it is composed of an optical detector consisting of a light-emitting element 9A as a light-emitting part and a light-receiving element 9B as a light-receiving part, which are disposed facing each other in the middle of the outlet tube 2B.
It is detected whether the refrigerant F flowing in the direction of arrow A within the outlet pipe 2B 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.
Detection voltage V as a detection signal from 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 warning lamp 11 when the refrigerant is properly filled.
The control circuit 10 is connected to the flow sensor 9 on the input side and to the notification lamp 11 on the output side. Then, when the refrigerant F in the pipe 2 reaches an appropriate filling amount, the control circuit 10 controls the notification lamp 11 based on the detected voltage V from the flow sensor 9 which becomes higher than the reference voltage Vi as a reference value is turned on to notify the operator that the refrigerant F in the pipe 2 has reached the appropriate amount.

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 compressor 3 is driven by the input, and the cooling cycle 1 is operated. Thereby, the refrigerant F in the pipe 2 is compressed and allowed 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 the refrigerant F derived from the Bubbles are generated, and the amount of light received by the light receiving element 9B is reduced.
The detected voltage V is lower than a predetermined voltage Vi serving as a reference value. Therefore, the control circuit 10 turns off the notification lamp 11 based on the detected voltage V to notify the operator that the amount of refrigerant F is insufficient.

When the refrigerant is charged from the outside into the pipe 2 as shown in FIG. 7 using a refrigerant filling device (not shown), when the refrigerant F reaches the appropriate filling amount, the refrigerant F enters a liquid phase. The bubbles in the refrigerant F disappear at the bubble disappearance point P, and the light receiving element 9B
Since the amount of light received increases, the detection voltage V becomes the predetermined voltage Vi
, the control circuit 10 lights up the notification lamp 11 to notify the operator that the refrigerant F has been properly filled.

[0015]

[Problems to be Solved by the Invention] However, in the above-mentioned prior art, when filling the pipe 2 with refrigerant using a refrigerant filling device or the like, the filling speed changes depending on the temperature of the refrigerant to be filled, and the temperature of the refrigerant changes. When the temperature is high, the filling speed becomes fast, and when the temperature is low, the filling speed becomes slow. When the temperature of the refrigerant to be filled is high, the filling speed becomes faster, so even if proper filling is achieved, bubbles are difficult to disappear up to the bubble extinction point P' as shown by the characteristic line indicated by the dotted line in FIG.

Therefore, in the prior art, when the temperature of the refrigerant to be filled is low, as shown by the solid line in FIG. Although it can be done, when the temperature of the refrigerant to be charged is high as shown by the dotted line, the bubble extinction point P' based on the predetermined voltage Vi is delayed as shown by the characteristic line shown by the dotted line, so it is difficult to follow the actual amount of refrigerant charged. There is a problem in that when the detected voltage V exceeds the predetermined voltage Vi, the refrigerant F has already entered the overfill region.

For this reason, the pressure of the refrigerant F in the cooling cycle 1 becomes excessively high, which tends to cause refrigerant leakage, and the load on the compressor 3 increases, causing the compressor 3 to seize.

The present invention was developed in view of the above-mentioned problems of the prior art, and the present invention prevents overfilling of refrigerant by changing the reference value for proper refrigerant charging according to the temperature of the refrigerant to be filled. The object of the present invention is to provide an air conditioner that can be appropriately filled with refrigerant.

[0019]

[Means for Solving the Problems] The features of the configuration adopted by the present invention in order to solve the above-mentioned problems are: a refrigerant charger connected to a flow path through which refrigerant circulates from the outside during refrigerant filling; A temperature sensor is provided between the refrigerant filling device and the flow path, and detects the temperature of the refrigerant filled in the flow path. a reference value setting means for variably setting a reference value corresponding to proper charging of refrigerant based on the signal; The present invention further includes filling state determining means for determining whether or not the reference value set by the value setting means has been exceeded.

[0020]

[Operation] With the above configuration, the temperature of the refrigerant to be filled can be detected based on the signal from the temperature sensor, and the reference value for determining the appropriate filling of the refrigerant can be variably set based on this temperature. By lowering the value, even if the detection signal from the refrigerant condition detector is low, it can be determined that the refrigerant is being filled properly.

[0021]

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

In the figure, reference numeral 21 indicates a refrigerant charger provided outside the cooling cycle 1. 2 is connected. Then, the filling device 2
Reference numeral 1 generally consists of a cylinder in which refrigerant is stored and an on-off valve (both not shown). By opening the on-off valve while the compressor 3 is driven, the refrigerant in the cylinder is released. Introduced into the piping 2 via the introduction pipe 22,
The cooling cycle 1 is filled with refrigerant.

Reference numeral 23 denotes a temperature sensor installed in the middle of the introduction pipe 22, which detects the temperature t of the refrigerant to be filled and outputs the detection signal to a control unit 24, which will be described later. It has become.

Reference numeral 24 indicates a control unit composed of a microcomputer, etc., and the input side of the control unit 24 has an air conditioner switch 25 and a flow control unit.
It is connected to the sensor 9, temperature sensor 23, etc., and the output side is connected to the notification lamp 11, etc. And the control
The refrigerant unit 24 stores the program shown in FIG. 4 in its memory circuit, and performs processing for determining the appropriate filling state to determine whether the refrigerant F flowing through the pipe 2 has reached the appropriate filling amount. ing. In addition, the memory circuit of the control unit 24 has a characteristic map (Fig. 3) etc. 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 proper filling state determination process by the control unit 24 will now be described with reference to FIG.

First, in step 1, turn on the air conditioner switch 2.
5 operates the compressor 3, and
The on-off valve of the filler 21 is opened and charging of refrigerant from the cylinder is started. Next, in step 2, the temperature t of the refrigerant to be filled is detected from the temperature sensor 23, and in step 3, the set voltage ViO corresponding to the refrigerant temperature t is read from the map of FIG. Then, in step 4, this set voltage ViO is set as a predetermined voltage Vi as a reference value.

Furthermore, in step 5, the flow sensor 9
The detected voltage V corresponding to the state of the refrigerant F flowing in the pipe 2 is read from the
It is determined whether or not it is larger than i, and when the determination is "NO", the detected voltage V is lower than the predetermined voltage Vi. Repeat the following process. Then, when it is determined as "YES" in step 6, the detected voltage V becomes higher than the predetermined voltage Vi, and it can be determined that the pipe 2 is filled with an appropriate amount of refrigerant F. Therefore, the process moves to step 7, and the alarm is sent. The lamp 11 is turned on to notify the operator that the refrigerant F has been properly filled. Thereafter, this process is stopped by stopping the compressor 3 and closing the on-off valve of the filling device 21.

Thus, according to this embodiment, the filling device 21
When the temperature of the refrigerant charged from
can be set low, it is possible to prevent a drop in tracking performance during detection due to changes in the temperature t of the refrigerant to be filled and the accompanying change in the filling speed, etc., and the refrigerant filling speed becomes faster, as shown by the dotted line in Figure 7. As shown in the characteristic line, the bubble disappearing point P'
By lowering the predetermined voltage Vi so that the detection voltage V exceeds the predetermined voltage Vi before the bubbles disappear, it is possible to reliably prevent the refrigerant F from overfilling and ensure accurate and proper filling. The time can be detected. As a result, the operator can always fill the cooling cycle 1 with a constant amount of refrigerant regardless of the temperature of the refrigerant in the cylinder of the charger 21, so that constant cooling efficiency can be obtained.

Furthermore, since overfilling of the refrigerant F can be prevented, excessive pressure can be prevented in the cooling cycle 1, bursting of the pipe 2 and refrigerant leakage can be effectively prevented, and It is possible to protect the compressor 3 by preventing a high load from being applied to the compressor 3. As a result, the life of the cooling device can be effectively extended.

In the above embodiment, steps 2 to 4 of the program shown in FIG.
Step 7 shows a specific example of the filling state determining means.

Furthermore, in the above embodiment, when the refrigerant is properly filled, the notification lamp 11 is turned on to notify the driver, but instead of this, an alarm buzzer, a voice synthesizer, etc. may be used. The refrigerant may be used to notify when the refrigerant is properly filled.

[0033]

As described in detail above, according to the present invention, when filling a refrigerant flow path with refrigerant, a refrigerant charger is connected to the flow path in order to fill the refrigerant into the flow path from the outside. A temperature sensor for detecting the temperature of the refrigerant filled in the flow path is provided between the filling device and the flow path, and a reference value setting means sets a reference value corresponding to proper charging of the refrigerant based on a signal from the temperature sensor. This is set to be variable, and the filling state determining means compares this reference value with the detection signal from the refrigerant state detector, and when the detection signal exceeds the reference value, it is determined that proper filling is performed. For example, when the temperature of the refrigerant to be filled is high, by setting the reference value low, it is possible to compensate for the increase in the refrigerant filling speed into the flow path, and it is possible to reliably prevent refrigerant from being overfilled. The life of the air conditioner can be effectively extended.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a state in which refrigerant is filled into a cooling device according to an embodiment of the present invention.

FIG. 2 is a control block diagram used in this embodiment.

FIG. 3 is an explanatory diagram showing a characteristic map of the set voltage with respect to the temperature of the refrigerant to be charged stored in the storage area of the control unit.

FIG. 4 is a flowchart showing a refrigerant appropriate filling determination process.

FIG. 5 is a circuit diagram showing a cooling device according to the prior art.

FIG. 6 is an explanatory diagram showing a receiver tank and the like.

FIG. 7 is a characteristic diagram showing the detection voltage of the flow sensor at high temperature and low temperature.

[Explanation of symbols]

1 Cooling cycle 2 Piping 3 Compressor 4 Condenser 5 Evaporator 9 Flow sensor (refrigerant state detector) 9A Light emitting element (light emitting part) 9B Light receiving element (light receiving part) 21 Refrigerant charger 23 Temperature sensor 24 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. An air conditioner comprising an optical refrigerant state detector that detects the refrigerant state in the flow path,
a refrigerant filling device connected to the flow path from the outside during refrigerant filling; a temperature sensor provided between the filling device and the flow path to detect the temperature of the refrigerant filled in the flow path; a reference value setting means for variably setting a reference value corresponding to proper filling of the refrigerant based on a signal from the temperature sensor when filling the refrigerant into the flow path from a refrigerant filling device; and a filling state determining means for determining when the refrigerant is properly filled based on whether or not a detection signal from the refrigerant state detector exceeds a reference value set by the reference value setting means. Characteristic air conditioning equipment.