JP2000130897A - Method and equipment for determining quantity of encapsulated refrigerant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the quantity of refrigerant required for optimal operation of an air conditioner correctly and easily. SOLUTION: An outdoor unit comprises a compressor 1, an outdoor heat exchanger 10, a liquid receiver 9, and an electronic expansion valve 8 the quantity of refrigerant encapsulated in an air conditioner constituted by coupling them through piping is determined. A refrigerant channel coupled with the outdoor heat exchanger 10 and a refrigerant channel coupled with an indoor heat exchanger 3 are coupled with the inlet channel of the liquid receiver 9 through check valves 5, 6 for switching inlet refrigerant channels. A refrigerant channel coupled sequentially with a cooler 20 coupled with the outlet channel of the liquid receiver 9, a sight glass 21 and the electronic expansion valve 8 is coupled with the indoor heat exchanger 3 and the outdoor heat exchanger 10 through check valves 4, 7 for switching outlet refrigerant channels. Quantity of encapsulated refrigerant can be determined while using the sight glass commonly for heating operation and cooling operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for judging the amount of refrigerant charged in an air conditioner, which detects whether or not the amount of refrigerant charged in the air conditioner is appropriate for the working condition.

[0002]

2. Description of the Related Art Conventionally, several techniques have been proposed as refrigerant charging amount judging devices for detecting whether or not a refrigerant amount charged in a refrigeration apparatus or an air conditioner is appropriate.

[0003] Generally, a refrigerating device used in an air conditioner or the like forms a refrigerant circuit by connecting a compressor, a condenser, a liquid receiver, a pressure reducing device, an evaporator, and the like with a pipe. A predetermined amount of refrigerant suitable for the construction state is sealed. When the refrigerating apparatus is operated, the refrigerant is compressed by the compressor into a high-temperature and high-pressure gas state, radiates heat by the condenser, is condensed and liquefied, and then flows into the receiver. Then, the liquid refrigerant flowing out of the liquid receiver is decompressed by the decompression device to be in a low pressure state and is evaporated by the evaporator. At that time, the refrigerant absorbs heat from the surroundings to exhibit a cooling effect. Here, when the refrigerant leaks from the refrigerant circuit and the amount of refrigerant in the refrigerant circuit is insufficient, the amount of liquid refrigerant in the receiver decreases, and flash gas (bubbles) is generated in the refrigerant flowing out of the receiver. As a result, the amount of refrigerant supplied to the evaporator becomes insufficient, and the cooling capacity is significantly reduced.

Therefore, in order to confirm that a refrigerant shortage has occurred, as described in Japanese Patent Publication No. 55-32991 and Japanese Patent Publication No. 56-1544, a receiver and a pressure reducing device are used. The connecting pipe section is provided with a sight glass for observing the flow of the refrigerant inside the pipe.
This sight glass has glass on one side, and some have an indicator for moisture management with a chemical substance called a moisture indicator inside, and the state of the refrigerant passing through the inside of the sight glass The structure is such that the generation of flash gas can be detected by visually observing through the glass.

In the refrigerating cycle described in Japanese Patent Application Laid-Open No. Hei 5-296620, a sight glass for detecting the excess or deficiency of the amount of refrigerant by bubbling of refrigerant between the liquid receiver and the pressure reducing device, And a refrigerant supercooling state forming means for making the refrigerant flowing out of the sight glass into a supercooling state at the inlet side of the sight glass, so that even if there is some pressure loss or pressure hunting occurring at the outlet side of the liquid receiver, the refrigerant Can be stably maintained, and only the bubbles visible in the sight glass are caused by the shortage of the amount of the charged refrigerant. Therefore, it is possible to accurately determine whether the amount of the charged refrigerant is excessive or insufficient.

[0006]

However, in the refrigerant charging amount determination apparatus described above, since the refrigeration cycle is based on the refrigeration apparatus, the refrigerant charging amount is determined only in one direction as the flow direction of the refrigerant. However, since it is not considered to apply to a heat pump in which the flow direction of the refrigerant is bidirectional, there are the following problems.

That is, in the case of the arrangement of the receiver used in the prior art, the sight glass or the cooling means and the sight glass are arranged at a portion corresponding to the outlet side of the receiver during the cooling operation. During cooling operation, it is possible to determine the normal amount of refrigerant charged.However, when a four-way valve or the like is provided as a heat pump device, during heating operation, the sight glass or cooling means and the flow direction of the sight glass refrigerant flow. When the position is on the inlet side of the receiver, the refrigerant on the inlet side of the receiver is always in a gas-liquid two-phase state because the receiver radiates heat to the outside air, and when the inside of the sight glass is visually observed, It is always in a state where bubbles are generated. Therefore, there is a problem that the refrigerant charging amount determination device used in the conventional technology cannot perform a normal determination during the heating operation.

[0008] Further, in order to provide a refrigerant charging amount determination device corresponding to a heat pump device, it is necessary to install a cooling means and a sight glass on both the inlet side and the outlet side of the liquid receiver. There is a problem that the cost is high.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional technical problems, and it is required that a minimum amount of refrigerant for optimally operating an air conditioner is sealed. It is an object of the present invention to provide an apparatus for judging the amount of charged refrigerant which can be accurately and easily detected at low cost in both the operation and the heating operation.

[0010]

The above object is achieved by at least one outdoor unit and at least one indoor unit,
The outdoor unit is composed of at least a compressor, an outdoor heat exchanger, a liquid receiver, and a decompression device. The indoor unit is composed of at least an indoor heat exchanger, and is connected to an air conditioner that is connected by piping. When a fixed amount of refrigerant is charged, in a refrigerant charging amount determination device that determines whether a refrigerant charging amount in the air conditioner is appropriate, a refrigerant flow path connected to the outdoor heat exchanger and the indoor heat exchanger The refrigerant flow path connected to
The refrigerant flow path connected to the inlet flow path of the liquid receiver through the inflow refrigerant flow switching means and connected to the outlet flow path of the liquid receiver includes at least a cooling means and a refrigerant charging amount in the middle. This is achieved by a configuration in which the determination means is inserted and the refrigerant flow path connected to the outdoor heat exchanger and the refrigerant flow path connected to the indoor heat exchanger are connected via the outflow refrigerant flow switching means. .

The object of the present invention is to provide a method for determining the amount of refrigerant enclosed in a refrigeration cycle by the refrigerant amount determination means in the refrigerant amount determination device. This is achieved by providing the refrigeration cycle with refrigeration cycle stability determination means for determining whether the refrigeration cycle is stable.

[0012] Further, the above object is to provide a liquid receiver installed in a refrigeration cycle of an air conditioner, comprising at least one outdoor unit and at least one indoor unit, and connecting these with piping. In the refrigerant charging amount determination method for determining whether the refrigerant amount sealed in the air conditioner is appropriate by the refrigerant amount determining means provided in the outlet flow path, the refrigerant amount required in the refrigeration cycle is the largest. The operation mode of the air conditioner is determined by at least the length of the pipe in which the air conditioner is installed.

According to the above-described means, the refrigerant flows into the liquid receiver from one direction, flows out of the refrigerant from one direction, and flows out of the liquid receiver during both the cooling operation and the heating operation of the air conditioner. The refrigerant enclosing amount determining means inserted in the refrigerant flow path through which the refrigerant flows out in one direction can determine whether the amount of the refrigerant enclosed in the air conditioner is appropriate for both the cooling operation and the heating operation. .

The timing of determining the amount of refrigerant sealed in the refrigeration cycle by the refrigerant amount determination means is controlled using a signal indicating whether the refrigeration cycle is stable by the refrigeration cycle stability determination means, The refrigerant enclosing amount determination is performed in a stable range where the change in the refrigerant amount is small, and the determination is performed accurately and accurately.

Further, the determination of the required refrigerant amount is performed by determining the operation mode in which the required refrigerant amount is the largest at least by the length of the connection pipe. When the connection pipe length is short, the difference in refrigerant volume between the outdoor heat exchanger and the indoor heat exchanger is larger than that due to the difference in the degree of refrigerant in the liquid connection pipe. However, when the connection pipe is long, the difference in the amount of refrigerant in the liquid connection pipe due to the difference in the degree of refrigerant is large, so that the required refrigerant quantity is larger during the heating operation. Therefore, in determining whether or not the amount of the charged refrigerant by the refrigerant charged amount determination means is appropriate, at least the connection pipe length is taken into consideration, the operation is performed in the operation mode in which the largest amount of the refrigerant is required, and the refrigerant is additionally charged. At that time, by judging the amount of refrigerant at that time, accurate judgment and additional encapsulation become possible.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a refrigeration cycle of an air conditioner provided with a refrigerant charging amount determination device according to one embodiment of the present invention. This air conditioner is configured by connecting one outdoor unit and one indoor unit by liquid-side and gas-side connection pipes.
The outdoor unit includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 10, a liquid receiver 9, and an accumulator 11, and is connected by piping as shown in the figure. Outdoor heat exchanger 10
In order to exchange heat with the outside air,
An outdoor fan 14 for sending air to the air conditioner and an outdoor fan motor 15 for driving the outdoor fan 14 are provided. On the other hand, the indoor unit is constituted by the indoor heat exchanger 3, and the indoor heat exchanger 3 is configured to exchange heat with the outside air.
An indoor fan 12 for sending air into the vehicle and an indoor fan motor 13 for driving the indoor fan 12 are provided.

In the present embodiment, as an inflow refrigerant flow path switching means attached to the inlet flow path of the liquid receiver 9, a refrigerant flow connecting the outdoor heat exchanger 10 and the inlet flow path of the liquid receiver 9 is provided. A third check valve 6 is provided in the passage, and a second check valve 5 is provided in a refrigerant flow path connecting the indoor heat exchanger 3 and the inlet flow path of the liquid receiver 9. Cooling means for supercooling a refrigerant flowing out of the liquid receiver 9 in an outlet flow path of the liquid receiver 9;
A refrigerant charging amount determining means for determining whether the refrigerant sealed in the air conditioner is appropriate or not, and a pressure reducing device are sequentially connected by piping. The cooling means includes a refrigerant flow path connecting the four-way valve 2 and the accumulator 11 and the liquid receiver 9.
The cooler 20 is brought into contact with the outlet flow path. Further, as the refrigerant enclosing amount determination means, a sight glass 21 is provided which has a transparent wall on one surface or an opposing surface which can be easily determined at low cost. Further, an electronic expansion valve 8 is employed as a pressure reducing device.

Further, as an outflow refrigerant flow path switching means attached to the outlet flow path of the liquid receiver 9, a cooler 20, a sight glass 21, an electronic expansion valve 8 connected to the outlet flow path of the liquid receiver 9 are provided. And the outdoor heat exchanger 1 formed by sequentially connecting
0, a fourth check valve 7 in the refrigerant flow path, and a cooler 20, a sight glass 2 connected to the outlet flow path of the liquid receiver 9.
1. The first check valve 4 is provided in a refrigerant flow path connecting the electronic heat expansion valve 8 and the indoor heat exchanger 3 in sequence.

Further, a discharge pressure detector 18 (for example, a pressure sensor) for measuring the pressure of the refrigerant discharged from the compressor 1 and a temperature of the discharged gas refrigerant are provided in the pipe on the compressor discharge side. A discharge temperature detector 17 (for example, a thermistor) is attached. The output signal of each detector is connected to each of the detectors by a signal line so as to be taken into the microcomputer 16, and the microcomputer 1 controls the compressor 1 for controlling the operation state of the refrigeration cycle. In order to send a control signal to each control device such as the electronic expansion valve 8 and the outdoor fan 14, it is connected to each control device by a signal line.

In such an air conditioner, during the heating operation, the refrigerant flows in the direction indicated by the dashed arrow, and the high-temperature and high-pressure gas refrigerant compressed by the compressor 1 is sent to the indoor heat exchanger 3 through the four-way valve 2. Then, heat is radiated to the air passing when condensed in the indoor heat exchanger 3 to become a liquid refrigerant, thereby heating the room. The condensed and liquefied refrigerant passes through the second check valve 5 because the flow toward the electronic expansion valve 8 is blocked by the first check valve 4, and moves toward the outdoor heat exchanger 10 by the third check valve 6. Flows into the liquid receiver 9 because the flow is blocked. The refrigerant flowing out of the receiver 9 is cooled by the cooler 20 and the sight glass 2.
1, the pressure is reduced to a predetermined pressure by the electronic expansion valve 8,
In the check valve 4, since the high-pressure refrigerant is on the outlet side, the refrigerant flows to the fourth check valve 7 side, flows into the outdoor heat exchanger 10, absorbs heat from the air passing through the outdoor heat exchanger 10, and evaporates. . The evaporated refrigerant returns to the compressor 1 through the four-way valve 2 and the accumulator 11.

On the other hand, during the cooling operation, the refrigerant flows in the direction indicated by the solid line arrow, and the high-temperature and high-pressure gas refrigerant compressed by the compressor 1 is sent to the outdoor heat exchanger 10 via the four-way valve 2 and the outdoor heat exchanger Heat is released to the air passing through the vessel 10 and is condensed to become a liquid refrigerant. Since the flow to the electronic expansion valve 8 side is blocked by the fourth check valve 7, it passes through the third check valve 6 and the second check. Since the flow toward the indoor heat exchanger 3 is blocked by the valve 5, it flows into the liquid receiver 9. The refrigerant flowing out of the liquid receiver 9 passes through the cooler 20 and the sight glass 21, and is reduced to a predetermined pressure by the electronic expansion valve 8, and the fourth check valve 7 has the high-pressure refrigerant on the outlet side. 1 The refrigerant flows to the check valve 4 side, flows into the indoor heat exchanger 3 through the liquid-side connection pipe, absorbs heat from the air that passes when the indoor heat exchanger 3 evaporates, and cools the room. Then, the evaporated refrigerant returns to the compressor 1 through the four-way valve 2 and the accumulator 11 through the gas side connection pipe.

That is, in the air conditioner of the present embodiment,
In both the cooling operation and the heating operation, the refrigerant flows into the liquid receiver 9 from one direction, the refrigerant flows out from one direction, and the refrigerant charging amount determination device is provided in the refrigerant flow path flowing out of the liquid receiver 9. It has an equipped cycle configuration.

A predetermined amount of refrigerant is sealed in the air conditioner, and the excess refrigerant in the circulation of the refrigerant is stored as a liquid refrigerant in a liquid receiver 9 provided in the outdoor unit.

Next, the relationship between the amount of liquid refrigerant in the liquid receiver 9 and the flow pattern in the sight glass 21 provided as the refrigerant enclosing amount determination means will be described.

FIG. 2 is a correlation diagram showing the relationship between the liquid level in the receiver 9 and the flow state in the sight glass 21 and the amount of refrigerant in the air conditioner. The liquid receiver 9 includes a tank for storing the refrigerant, an introduction pipe 25 for guiding the refrigerant into the liquid receiver 9, and an outlet pipe 26 for discharging the refrigerant from the liquid receiver 9. The leading ends of the inlet pipe 25 and the outlet pipe 26 are obliquely cut in order to continuously change the refrigerant cleanliness on the outlet side of the receiver 9 with respect to the liquid level change.

The liquid level of the liquid refrigerant stored in the liquid receiver 9 is determined by the outlet pipe 26 for discharging the refrigerant from the liquid receiver 9.
If it is in the portion cut obliquely at the tip of the compressor, it flows out in a state of high cuteness because both the liquid refrigerant and the gas refrigerant are sucked from the tip, and the heat is exchanged by the cooler 20 with the pipe on the compressor suction side. Even if heat is dissipated, the inside of the sight glass 21 is in a gas-liquid two-phase state because it cannot be supercooled. On the other hand, when there is a liquid surface above the diagonally cut portion of the leading end of the outlet pipe 26, only the liquid refrigerant is sucked from the leading end, and the cooler 20 exchanges heat with the pipe on the compressor suction side to release heat. Then, the inside of the sight glass 21 becomes a liquid single-phase state because it becomes a supercooled liquid.

Here, when the air conditioner is operated in a certain operation mode, the liquid refrigerant stored in the receiver 9 is a refrigerant that is not necessary for forming a refrigeration cycle, and is not used in that operation mode. Necessary refrigerant. That is, the proper state of the refrigerant sealed in the air conditioner is a case where the liquid refrigerant stored in the liquid receiver 9 is the least,
Moreover, this is the case where the flow mode in the sight glass 21 changes from the gas-liquid two-phase state to the liquid single-phase state.

However, when the cooling mode and the heating mode are used as the operation modes, the amount of refrigerant required for the refrigeration cycle depends on the length of the connection pipe and the temperature of the air in which the indoor and outdoor units are installed. Are different. Therefore, in order to determine whether the amount of refrigerant enclosed in the air conditioner is appropriate, in consideration of the operation mode, connection pipe length, air temperature conditions, and the like, in the operation state where the largest amount of refrigerant is required. It is necessary to visually determine that the inside of the sight glass 21 changes from the gas-liquid two-phase state to the liquid single-phase state when the air conditioner is operated and the refrigerant is additionally charged.

For example, in the case of an air conditioner having a refrigeration cycle configuration shown in FIG. 1, the connection pipe length is reduced as shown in the relationship diagram of FIG. In a short case, the difference in the refrigerant volume due to the pipe volume ratio between the outdoor heat exchanger 10 and the indoor heat exchanger 3 is larger than the difference in the refrigerant amount due to the difference in the degree of refrigerant in the liquid connection pipe. Although the required refrigerant amount increases, when the connection pipe is long, the refrigerant amount difference due to the difference in the degree of refrigerant in the liquid connection pipe increases, so that the required refrigerant amount is larger during the heating operation.

Next, a description will be given of a determination method of the refrigerant charging amount determination device of the present embodiment with reference to FIGS. FIG. 4 is a flowchart showing the configuration of the determination method by the refrigerant enclosing amount determination device of the present invention, and FIG. 5 is a characteristic diagram showing a change in the discharge gas refrigerant temperature Td with the elapse of the operation time.

First, after the construction of the air conditioner is completed, the air in the connection pipes other than the outdoor unit and the air in the indoor unit is drawn out by a vacuum pump to be in a vacuum state. In the outdoor unit, the refrigerant for the minimum connection pipe and the indoor unit is charged before shipment of the outdoor unit, or the amount of the refrigerant is charged at the construction site. Next, the cooling mode or the heating mode is determined as the operation mode of the air conditioner from the connection pipe length, the air temperature at which the air conditioner is installed, and the like, and the air conditioner starts operating in the determined operation mode. I do.

Next, a compressor discharge side temperature detector 17 is used as a refrigerating cycle stability determination means, and the compressor discharge gas refrigerant temperature Td after the start of operation is detected by the discharge temperature detector 17 (for example, a thermistor). Microcomputer 16
To send the detection signal. The microcomputer 16
As an embodiment of the signal of the discharge gas refrigerant temperature input to the controller, there is a change in the discharge gas refrigerant temperature Td with respect to the elapse of the operation time shown in FIG. In FIG. 5, when the operation is started from the initial discharge gas refrigerant temperature T0, the electronic expansion valve 8 is controlled such that the temperature rises with time and the discharge gas refrigerant temperature falls within the target discharge temperature range (T1 <Td <T2). Then, while hunting around the target discharge temperature range, after a certain elapsed time from the start of the operation (t1-t0), the temperature converges to the target discharge temperature range (T1 <Td <T2).

Here, in the microcomputer 16,
It is determined whether or not the detected discharge gas refrigerant temperature Td is within the target discharge temperature range. When the discharge gas refrigerant temperature Td is lower than the target discharge temperature range, the low-pressure side refrigerant dryness decreases and the required amount of refrigerant in the refrigeration cycle increases. When the discharge gas refrigerant temperature Td is higher than the target discharge temperature range, the low-pressure side refrigerant dryness decreases. As the temperature increases, the required amount of refrigerant in the refrigeration cycle decreases.
For this reason, outside the target discharge temperature range, the required refrigerant amount in the refrigeration cycle changes extremely, so that accurate determination cannot be made.

If it can be confirmed that the discharge gas refrigerant temperature is within the target discharge temperature range, it means that the required refrigerant amount in the refrigeration cycle can be accurately measured. Thus, a refrigerant-filled-amount determination signal is output so that the sight glass 21 can be viewed. At this time, the determinable signal is output to an output device such as light (for example, an LED light emitting element) or a sound (for example, a speaker), or a terminal device such as a personal computer installed in a state capable of communicating with the air conditioner. Of the air conditioner or the display of the remote controller of the air conditioner.

The refrigerating cycle stability determination means uses a temperature detector 17 and a pressure detector 18 on the compressor discharge side, and the microcomputer 16 calculates the degree of superheat of the discharged gas from the temperature detector 17 and the pressure detector 18. I do. When the value of the discharge gas superheat degree calculation device is within the target discharge gas superheat degree range for a certain period or more, it is determined that the refrigeration cycle is stable. This determination result can be similarly output as the timing for determining the amount of charged refrigerant.

Next, the worker for judging the amount of charged refrigerant visually checks the flow pattern in the sight glass 21. Here, when the flow mode in the sight glass 21 is in a liquid single-phase state, the amount of the refrigerant sealed in the air conditioner can be determined to be appropriate because the initially charged refrigerant amount is the minimum necessary refrigerant amount.

On the other hand, when the flow mode in the sight glass 21 is a gas-liquid two-phase state or an intermittent flow in which the gas-liquid two-phase state and the liquid single-phase state alternately flow, the liquid refrigerant stored in the receiver 9 is used. This indicates that the cycle is not in a state where the amount is small and normal operation can be performed. That is, it can be determined that the amount of the refrigerant sealed in the air conditioner is too small. here,
Since normal operation cannot be continued in this state, the refrigerant is added until the flow mode in the sight glass 21 changes from the gas-liquid two-phase state to the liquid single-phase state. Thereby, it is possible to fill in the minimum necessary refrigerant amount suitable for the construction state of the air conditioner.

As described above, in the refrigerant charging amount judging device according to the present embodiment, the refrigerant amount required during the refrigeration cycle is the largest depending on the length of the connection pipe of the air conditioner and the air temperature conditions during operation. The air conditioner is operated in the operation mode in which the air conditioner can be operated normally and the refrigerant amount stored in the liquid receiver 9 passes through the sight glass 21 to determine whether or not the refrigerant amount is the minimum necessary refrigerant amount. By determining based on the flow mode of the refrigerant, it is possible to accurately determine whether the amount of the refrigerant sealed in the air conditioner is appropriate.

In addition, since the path of the refrigerant flowing into or out of the liquid receiver 9 in one direction during both the heating operation and the cooling operation is unidirectional, the refrigerant enclosing amount judging means inserted into the refrigerant flow path Can be shared, so that the cost of the air conditioner can be reduced and the size can be reduced.

Furthermore, the use of check valves as the inflow refrigerant flow switching means and the outflow refrigerant flow switching means for making the flow of the refrigerant flowing into or out of the liquid receiver 9 in one direction makes it possible to reduce the refrigerant flow. Can be made inexpensively as a device for making the route of the air conditioner unidirectional, and the cost of the air conditioner can be reduced.

Further, the timing of visually checking the flow mode of the sight glass 21 is performed when the temperature of the discharged gas refrigerant is within the target discharge temperature range where the change in the refrigerant amount is small. It can be carried out.

Further, by disposing a device for supercooling the refrigerant in front of the sight glass 21, pressure loss, pressure pulsation, and the pressure in the liquid receiver 9 despite the proper refrigerant being enclosed.
Instability of the flow pattern in the sight glass 21 which occurs when the liquid level of the liquid is unstable can be eliminated, and the refrigerant charging amount can be accurately determined.

Further, as the supercooling device for the refrigerant, a suction side pipe connecting the four-way valve 2 and the accumulator 11 is structured to be in contact with a pipe connecting the liquid receiver 9 and the sight glass 21, thereby providing a cooling means. The cost of the air conditioner can be reduced compared to a double-pipe heat exchanger or a cascade heat exchanger which requires high installation cost and large installation space.

Here, the timing of visually checking the flow mode of the sight glass 21 has been described using the discharge gas refrigerant temperature, but the suction gas superheat, which is the difference between the suction gas refrigerant temperature and the saturated gas refrigerant temperature obtained from the suction pressure, is described. When the degree is used, since the state of the refrigerant on the suction side can be always constant,
A change in the amount of refrigerant can be suppressed. In addition, when the discharge gas superheat degree, which is the difference between the discharge gas refrigerant temperature and the saturated gas temperature determined from the discharge pressure, is used, the state of the refrigerant on the suction side can be kept constant even when the suction side is wet, A change in the amount of refrigerant can be suppressed, and the use of the superheat degree of the suction gas and the superheat degree of the discharge gas does not depart from the scope of the present invention.

Next, as another embodiment of the present invention, an inflow refrigerant flow path switch provided so that the flow path of the refrigerant flowing into or out of the liquid receiver 9 in one direction during both the heating operation and the cooling operation is one direction. Another configuration of the means and the outflow refrigerant flow path switching means will be described.

FIG. 6 shows an inflow refrigerant flow switching means and an outflow refrigerant flow switching means provided so that the flow path of the refrigerant flowing into or out of the liquid receiver 9 used in the refrigerant filling amount judging device is one-way. FIG. 10 is a cycle configuration diagram showing another embodiment.
6, the same components as those in FIG. 1 indicate the same components.

The inflow refrigerant flow switching means and the outflow refrigerant flow switching means of the present embodiment include a refrigerant flow path connected to the indoor heat exchanger 3, a refrigerant flow path connected to the outdoor heat exchanger 10,
A second four-way valve 22 connects a refrigerant flow path formed by sequentially connecting a cooler 20, a sight glass 21, and an electronic expansion valve 8 connected to an inlet flow path of the liquid receiver 9 and an outlet flow path of the liquid receiver 9. It is configured to be connected via a. Thereby, the refrigeration cycle is simplified and the number of welding points can be reduced, so that the reliability of the refrigeration cycle against failure is improved.

Next, as another embodiment of the present invention, a cycle configuration in which the most required operation mode is always the same operation mode will be described.

FIG. 7 is a cycle configuration diagram showing an embodiment of an air conditioner equipped with a refrigerant enclosing amount determining device which can always perform the same operation mode when judging the refrigerant enclosing amount. 7, the same components as those in FIG. 1 indicate the same components.

In this embodiment, the indoor heat exchanger 3 and the liquid receiver 9 serve as expansion valves for expanding a high-pressure refrigerant into a low-pressure refrigerant.
The first expansion valve 23 is connected between the outdoor heat exchanger 10 and the liquid receiver 9.
The second expansion valve 24 is disposed between them. First
The opening degree of the expansion valve 23 and the second expansion valve 24 is controlled by the following method.

In the heating operation, the first expansion valve 23 is almost fully opened, and the second expansion valve 24 reduces the discharge gas refrigerant temperature to an opening required for keeping the discharge gas refrigerant temperature within the target discharge temperature range.
On the other hand, in the case of the cooling operation, the second expansion valve 24 is fully opened or almost fully opened, and the first expansion valve 23 reduces the discharge gas refrigerant temperature to an opening degree necessary for keeping the discharge gas refrigerant temperature within the target discharge temperature range.

That is, the expansion valve in front of the liquid receiver 9 with respect to the flow direction of the refrigerant is fully opened or almost fully opened,
This is a method in which the expansion valve after the liquid receiver 9 reduces the discharge gas refrigerant temperature to an opening required to keep the discharge gas refrigerant temperature within the target discharge temperature range. As a result, the refrigerant in the liquid connection pipe is in a gas-liquid two-phase state because a small amount of heat is radiated in the receiver 9 in the heating operation, and the refrigerant flowing out of the receiver 9 is in the cooling operation. Since it is supercooled by the cooler 20, it becomes a liquid single phase state. Therefore, when the air conditioner is operated, the required amount of refrigerant increases in the cooling operation in which the inside of the liquid connection pipe is in a liquid single phase state and the pipe volume of the heat exchanger acting as a condenser is large.

As described above, the expansion valves are arranged before and after the liquid receiver 9, and the expansion valve before the liquid receiver 9 is fully opened or almost fully opened with respect to the flow direction of the refrigerant. By restricting the expansion valve, the cooling mode can always be the operation mode that is required most often, and it is possible to suppress a decrease in the accuracy of the determination that occurs when the operation mode is erroneously determined when determining the amount of the charged refrigerant.

Here, in the present embodiment, a cycle configuration in which one indoor unit is connected to one outdoor unit has been described. However, one outdoor unit provided with the second expansion valve 24 shown in FIG. The indoor heat exchangers 3a, 3b, 3c and the first expansion valves 23a, 2
3b, 23c and a plurality of indoor units
The same applies to the multi-room type air conditioner connected via 9 when the cooling operation of all the connected indoor units is the same as in the present embodiment, and does not depart from the scope of the present invention.

In the case of the multi-room air conditioner shown in FIG. 8, an operation mode that requires a larger amount of refrigerant than that required when all the indoor units are cooled (for example, one indoor unit having the minimum capacity). Is a heating operation, and the other indoor units have a blowing operation. Even in such a case, since the flow direction of the refrigerant flowing into and out of the liquid receiver 9 is set to one direction, it is not necessary to provide an extra cooling unit or a refrigerant charging amount determining unit depending on the operation mode, and the refrigerant charging amount is reduced. Since the determination can be made, the size of the air conditioner can be reduced, and the cost can be reduced.

Next, as another embodiment of the present invention, another structure of the refrigerant charging amount determining means will be described.

FIG. 9 is a block diagram showing another embodiment of the refrigerant charging amount judging means used in the refrigerant charging amount judging device. The refrigerant enclosing amount determination means of the present embodiment includes an ultrasonic transmission element 2 outside the pipe connecting the cooler 20 and the electronic expansion valve 8.
7 and an ultrasonic receiving element 28, and the ultrasonic transmitting element 2
7, a control circuit 29 for judging whether the inside of the pipe is a liquid single phase or a gas-liquid two phase from the signal processing of the ultrasonic receiving element 28 and the transmission and reception signals is connected by signal input / output lines 30a and 30b. And

In this embodiment, when the flow mode of the refrigerant passing through the pipe connecting the cooler 20 and the electronic expansion valve 8 is in a liquid single-phase state, the refrigerant is transmitted between the ultrasonic transmitting element 27 and the ultrasonic receiving element 28. Is changed only between the pipe wall surface and the liquid refrigerant, the sound wave output from the ultrasonic transmitting element 27 reaches the ultrasonic receiving element 28 without being attenuated much.

On the other hand, when the flow of the refrigerant passing through the pipe connecting the cooler 20 and the electronic expansion valve 8 is a gas-liquid two-phase state or an intermittent flow in which a gas-liquid two-phase state and a liquid single-phase state alternately flow. Since the density change between the ultrasonic transmitting element 27 and the ultrasonic receiving element 28 occurs between the pipe wall surface and the liquid refrigerant and between the liquid refrigerant and the bubbles, the sound wave output from the ultrasonic transmitting element 27 Arrives at the ultrasonic receiving element 28 in inverse proportion to the amount.

Since the amount of air bubbles is proportional to the shortage of the refrigerant sealed in the refrigeration cycle, by measuring the amount of sound waves received by the ultrasonic receiving element 28, It is possible to determine how much the amount of refrigerant enclosed in the inside is insufficient. In addition, by converting the amount of sound waves received by the ultrasonic wave receiving element 28 into an electric signal in the control circuit 29, the sight glass 21 can automatically confirm the flow pattern visually checked by the operator. In addition, the determination of the amount of charged refrigerant can be automated.

FIG. 10 is a block diagram showing still another embodiment of the refrigerant charging amount judging means used in the refrigerant charging amount judging device. The refrigerant charging amount determination means of the present embodiment includes a capacitance sensor 31 having two electrodes disposed in a pipe connecting the cooler 20 and the electronic expansion valve 8, and a signal processing means for processing the signal of the capacitance sensor 31. A determination circuit 32 for determining whether the inside is a liquid single phase or a gas-liquid two phase is connected by signal output lines 33a and 33b.

In this embodiment, when the flow mode of the refrigerant passing through the pipe connecting the cooler 20 and the electronic expansion valve 8 is a single-phase liquid, all the electrodes of the capacitance sensor 31 are filled with the liquid refrigerant. Therefore, a capacitance value corresponding to the dielectric constant of the liquid refrigerant is output.

On the other hand, when the flow mode of the refrigerant passing through the pipe connecting the cooler 20 and the electronic expansion valve 8 is a gas-liquid two-phase state or an intermittent flow in which the gas-liquid two-phase state and the liquid single-phase state alternately flow. Since the ratio of the liquid refrigerant and the gas refrigerant to the total area of the electrodes of the capacitance sensor 31 changes according to the amount of bubbles, the output signal from the capacitance sensor 31 corresponds to the dielectric constant of the liquid refrigerant. The output value changes between the capacitance value of the gas refrigerant and the capacitance value corresponding to the dielectric constant of the gas refrigerant.

Therefore, when the output signal from the capacitance sensor 31 is stable, it can be determined that the liquid is in a single-phase state, and when the output signal is unstable, it is determined that the liquid-gas is in a two-phase state. Whether it is appropriate or not can be determined. here,
The output signal of the capacitance sensor 31 is converted into an electrical signal in the determination circuit 32 and transmitted to the microcomputer 16 to perform signal processing. It is possible to automatically check the flowing flow mode, and to automatically determine the amount of the charged refrigerant.

Further, instead of the ultrasonic wave transmitting element 27 and the ultrasonic wave receiving element 28 and the capacitance sensor 31, the pipe on the refrigerant outflow side of the cooling means may be made a transparent wall, or the refrigerant charged amount judging means may be opposed to the cooling means. As a sight glass 21 having a pair of transparent walls, a light emitting element is provided on one side of the transparent wall, and a light receiving element is provided on the other opposing transparent wall.
The same effect is obtained because the light transmittance is different between the liquid single-phase state and the gas-liquid two-phase state.

[0067]

As described above, according to the present invention, since the path of the refrigerant flowing into or out of the receiver in one direction during both the heating operation and the cooling operation is one-way, one refrigerant charging amount judging means is provided. It can be shared, and it is possible to determine the amount of refrigerant charged in common even in cooling operation and heating operation,
The cost of the air conditioner can be reduced and the size can be reduced.

Further, in the present invention, the timing for judging the refrigerant amount is determined by the refrigeration cycle stability judgment means to judge whether the refrigeration cycle is stabilized, so that a stable and reliable judgment can always be made.

Further, in the present invention, since the operation mode in which the amount of refrigerant required in the refrigeration cycle is the largest is determined by determining at least the length of the pipe in which the air conditioner is installed, an appropriate refrigerant amount is determined. It is possible to make a determination, and it is possible to provide an air conditioner that operates normally, reliably, and reliably without running out of the refrigerant amount in the air conditioner regardless of the operation mode.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle according to an embodiment of the present invention.

FIG. 2 is a correlation diagram showing a relationship between a liquid level of a liquid receiver, a flow mode in a sight glass, and determination of a refrigerant amount.

FIG. 3 is a relationship diagram showing a relationship between a connection pipe length, an operation mode, and a required refrigerant amount.

FIG. 4 is a flowchart illustrating a determination method according to the present invention.

FIG. 5 is a graph showing a temperature change characteristic of a discharge gas refrigerant.

FIG. 6 is a configuration diagram of a refrigeration cycle according to another embodiment of the present invention.

FIG. 7 is a configuration diagram of a refrigeration cycle according to another embodiment of the present invention.

FIG. 8 is a configuration diagram of a refrigeration cycle according to another embodiment of the present invention.

FIG. 9 is a configuration diagram of another embodiment of the refrigerant enclosing amount determination means of the present invention.

FIG. 10 is a configuration diagram of another embodiment of the refrigerant charging amount determination means of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... 4-way valve, 3 ... Indoor heat exchanger, 4 ... First
Check valve, 5: second check valve, 6: third check valve, 7: fourth check valve, 8: electronic expansion valve, 9: liquid receiver, 10: outdoor heat exchanger, 11: accumulator , 12 ... indoor fan, 13 ...
Indoor fan motor, 14 outdoor fan, 15 outdoor fan motor, 16 microcomputer, 17 discharge temperature detector, 18 discharge pressure detector, 19 branching device, 2
0: cooler, 21: sight glass, 22: second four-way valve,
23, 23a, 23b, 23c ... first expansion valve, 24 ... second expansion valve, 25 ... introduction pipe, 26 ... outlet pipe, 27 ... ultrasonic transmission element, 28 ... ultrasonic reception element, 29 ... control circuit, 30a , 30b: signal input / output line, 31: capacitance sensor, 32: determination circuit, 33a, 33b: signal output line.

Continuing on the front page (72) Inventor Shinichiro Yamada 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Air Conditioning Systems Division, Hitachi, Ltd. (72) Inventor Kenichi Nakamura 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Air Conditioning Systems Division, Hitachi, Ltd. 72) Inventor Hiroshi Takenaka 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside Air Conditioning Systems Division, Hitachi, Ltd.

Claims (3)

[Claims] 1. An outdoor unit including at least a compressor, an outdoor heat exchanger, a liquid receiver, and a decompression device, an indoor unit including at least an indoor heat exchanger, and air connected by piping. When the specified refrigerant is sealed in the harmony machine,
In the refrigerant charging amount determination device that determines whether the refrigerant charging amount in the air conditioner is appropriate, the refrigerant flow path connected to the outdoor heat exchanger and the refrigerant flow path connected to the indoor heat exchanger, The refrigerant flow path connected to the inlet flow path of the liquid receiver through the inflow refrigerant flow switching means and connected to the outlet flow path of the liquid receiver includes at least a cooling means and a refrigerant charging amount in the middle. A determination means is inserted, and the refrigerant flow path is connected to the refrigerant flow path connected to the outdoor heat exchanger and the refrigerant flow path connected to the indoor heat exchanger via the outflow refrigerant flow switching means. A refrigerant charging amount determination device. 2. The refrigeration of the air conditioner according to claim 1, wherein the refrigeration of the air conditioner is controlled in order to control a timing of determining the amount of the refrigerant sealed in the refrigeration cycle by the refrigerant enclosing amount determining means. A refrigeration cycle stability determining device for determining whether the refrigeration cycle is stable during a cycle is provided. 3. At least one outdoor unit and at least one outdoor unit
And an indoor unit, which is connected to the air conditioner by piping, and sealed in the air conditioner by refrigerant charging amount determining means provided in an outlet flow path of a receiver installed in a refrigeration cycle of the air conditioner. In the method for judging the amount of charged refrigerant, which determines whether the amount of refrigerant is appropriate or not, the operation mode of the air conditioner in which the amount of refrigerant required in the refrigeration cycle is the largest is at least when the air conditioner is installed. A method of determining the amount of charged refrigerant, wherein the method is determined based on the length of the pipe.