JPH0320664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a refrigeration cycle in an air conditioner, a refrigerator, a refrigeration device, etc.

[Prior art and its problems]

Normally, an air conditioner is selected that has the ability to perform sufficient air conditioning at a load close to the maximum load. Most of the time, the vehicle is operated at ambient temperatures below that temperature. Figure 1 shows the relationship between outside air temperature and cooling load when keeping the room temperature constant.
A ₁ is the cooling load at ℃, and the cooling load at the average outside temperature during the cooling period (29℃ in this example).
Assuming A ₂ , A ₂ is usually less than half of A ₁ , and an air conditioner with a capacity of A ₁ will have an excessive capacity for most of the cooling period. Conventionally, a thermostat detects the room temperature and uses the signal to control the compressor on and off to prevent the room temperature from dropping too low. FIG. 2 shows the relationship between room temperature and time in this conventional device. In FIG. 2, the line down to the right indicates that the air conditioner is in cooling operation (the compressor is in operation), and the line that rises to the right indicates that the air conditioner is not in cooling mode (the compressor is in operation). Line D shows the case where the thermostat setting value is 27°C and the thermodifferential is 4deg°C. In this case, the compressor is stopped when the room temperature drops to 25°C, and then the room temperature rises due to the cooling load, and when it reaches 29°C, cooling operation is resumed. Line E shows the case where the thermostat setting is 27°C and the thermodifferential is 1°C. In this case, the room temperature fluctuates between 26.5°C and 27.5°C, but the number of times the compressor starts and stops is four times that of line D.

Since the comfortable temperature range is said to be approximately between 18°C and 28°C, line D has an uncomfortable zone (the shaded area in the diagram), so in many cases the thermostat setting is set to 26°C, for example. lowered to ℃. Figure 3 shows the relationship between the cooling load and the room temperature under a constant outside temperature.When the thermostat setting is changed from 27℃ to 26℃, the cooling load changes from line B to line C. The compressor operating time ratio increases accordingly. Line F in Figure 2 indicates that the thermostat setting is 26℃ and the thermodifferential
The case of 4 degrees Celsius is shown, and in the case of line F, the operating time is longer than in line D, and the energy consumption of the air conditioner increases.

As described above, in order to achieve comfortable and energy-saving operation, it is important to reduce the thermodifferential.

When reducing the thermo differential,
There are two important obstacles: The first problem is restarting the compressor. In other words, immediately after the compressor is stopped, its discharge pipe is at high pressure and its suction pipe is at low pressure, and after the compressor is stopped, refrigerant flows from the high pressure side to the low pressure side through the throttle pipe section in the refrigerant circuit. The pressure is equalized. However, if the thermodifferential is made smaller, the start/stop interval becomes shorter, so it is necessary to ensure that the pressure on the discharge and suction sides of the compressor is equalized within a specified period of time (approximately 3 minutes). . If the pressure is not equalized, the compressor will start against the differential pressure, causing startup failure and failure to restart.

The second problem is heat loss due to the start and stop of the compressor. Figure 4 shows an example of the refrigerant circuit of an air conditioner. During cooling, the high-temperature, high-pressure gaseous refrigerant that exits the compressor 1 passes through the four-way switching valve 2, as shown by the solid line arrow, and goes outside. In heat exchanger 3, it condenses and becomes high temperature.
The liquid becomes a high-pressure liquid, and when it passes through the throttle 4, it is depressurized and becomes a low-temperature, low-pressure liquid, which enters the indoor heat exchanger 5 and evaporates there. This heat of evaporation cools the indoor air for air conditioning. Furthermore, the refrigerant evaporated and vaporized in the indoor heat exchanger 5 passes through the accumulator 6 and returns to the compressor 1.
be sucked into.

During heating, the refrigerant flows as shown by the dotted arrow. now,
It is assumed that the compressor 1 is stopped during this cooling operation. Since the aperture 4 and the compressor 1 are the boundaries, there are two states: a low temperature/low pressure side including the indoor heat exchanger 5 and a high temperature/high pressure side including the outdoor heat exchanger 3.
The refrigerant on the high pressure side flows into the low pressure side through the throttle 4. Therefore, the pressure and temperature on the low-pressure side rise, and the pressure and temperature on the high-pressure side fall. This movement of the refrigerant continues until the high pressure side and the low pressure side reach a pressure balance.

However, it has become clear that the conventional air conditioner described above suffers the following losses after undergoing the above process. In other words, most of the refrigerant sealed in the refrigeration cycle exists in the cycle as a liquid refrigerant, and during steady operation, most of the refrigerant is concentrated in the condenser (in the outdoor heat exchanger 3 during cooling). It exists as a liquid refrigerant in the conduit leading from the condenser to the throttle 4. When the compressor 1 is stopped, most of the liquid refrigerant in the condenser (outdoor heat exchanger 3 during cooling) flows through the throttle 4 to the evaporator (indoor heat exchanger 5 during cooling). This means that the liquid refrigerant is concentrated on one side. When the compressor 1 is restarted in such a refrigerant distribution state,
Most of the liquid refrigerant in the evaporator flows into the accumulator 6, and since there is not enough liquid refrigerant in the condenser, very little refrigerant is supplied to the evaporator through the throttle 4. As a result, there is no liquid refrigerant to evaporate in the evaporator, and even when the compressor 1 is started, the temperature of the blown air does not come down easily, and it takes 2 to 3 minutes to blow out cold air, resulting in poor air conditioning. It was a perfect opportunity.

FIG. 5 shows an experimental example of changes in the suction temperature, outlet temperature, and temperature at the center of the evaporator of the air conditioner when the compressor 1 is restarted during cooling operation in such a conventional example. In the figure, G indicates the intake air temperature of the air conditioner, H indicates the outlet air temperature of the air conditioner, and I indicates the temperature at the center of the evaporator (indoor heat exchanger 5). When the compressor 1 is restarted, the pressure inside the evaporator decreases, so the temperature of the evaporator drops, but since liquid refrigerant is not supplied from the condenser through the throttle 4, it is heated by the suction air. It shows a phenomenon where the value increases and then decreases. For this reason, the blowing temperature H does not decrease easily, and the result shows that it takes 2 to 3 minutes before the cold air is blown out steadily.

The above heat loss increases as the number of times the compressor starts and stops increases, and becomes a cause of a significant decrease in the annual energy efficiency of the air conditioner. The above is the same even during heating, although the flow of refrigerant is different and the heights of temperature and pressure are reversed.

[Object of the Invention] The present invention has been made in view of the above points, and provides a refrigeration cycle equipped with a refrigerant circuit in which refrigerant circulates through a compressor, a condenser, a throttle, and an evaporator in this order.
A refrigerant storage container is connected to an appropriate position of the refrigerant circuit that includes the throttle and reaches the evaporator via a connecting pipe, and heat is exchanged between the refrigerant storage container and the suction pipe of the compressor, and the connecting pipe The key point is that a valve is installed inside the compressor that opens when the compressor starts and closes when it stops, which reduces heat loss and also connects the compressor discharge pipe and suction when the compressor is restarted. The purpose is to provide a refrigeration cycle in which no differential pressure occurs in the pipes.

[Embodiments of the invention]

The details of the present invention will be explained below with reference to the embodiment shown in FIG. In FIG. 6, 11 is a compressor;
12 is a four-way switching valve, 13 is an outdoor heat exchanger, 14
15 is an indoor heat exchanger, 16 is an accumulator, 17 is a refrigerant storage container, 18 is a connecting pipe connecting the refrigerant storage container 17 and the refrigerant circuit, 19 is a connecting pipe 1
8 is an on-off valve arranged, 20 is a refrigerant storage container 17
This is the refrigerant pipe that exchanges heat with the refrigerant pipe.

In the present invention, the refrigerant storage container 17 is arranged to exchange heat with the refrigerant pipe 20 of the compressor 11. Further, the container 17 is referred to as a refrigerant circuit due to the connecting pipe 18. The connection point is aperture 1
4 and is connected to an appropriate position of the piping leading to the evaporator. In this case, the evaporator corresponds to the indoor heat exchanger 15 during cooling operation, and corresponds to the outdoor heat exchanger 13 during heating operation. Furthermore, the connecting pipe 18
An on-off valve 19 is installed in the compressor, and this on-off valve 19 opens when the compressor 11 is started and closes when the compressor 11 is stopped.

Next, the operation of the above embodiment will be explained. During cooling, as shown by the solid line arrow, the high temperature exiting the compressor 11,
The high-pressure gaseous refrigerant passes through the four-way switching valve 12, condenses in the outdoor heat exchanger 13, becomes a high-temperature, high-pressure liquid, and is depressurized as it passes through the throttle 14, becoming a low-temperature, low-pressure liquid, which is then used for indoor heat exchange. It enters vessel 15 and evaporates here. This heat of evaporation cools the indoor air for air conditioning. Further, the refrigerant evaporated and vaporized in the indoor heat exchanger 15 is sucked into the compressor 11 again through the four-way switching valve 12, the piping 20, and the accumulator 16.

Furthermore, inside the refrigerant storage container 17, a connecting pipe 18
The pressure corresponds to the connection point of the refrigerant circuit (point J in Figure 6). When the compressor 11 is operating in a steady state, the pressure at point J is an intermediate pressure that is the sum of the suction pressure (low pressure) of the compressor 11 and the pressure loss due to the flow of refrigerant. Therefore, the on-off valve 19 is open in the refrigerant storage container 17.
Refrigerant gas at intermediate pressure enters. On the other hand, the container 17 is connected to a pipe 20 through which a low-temperature, low-pressure refrigerant flows.
It is cooled by For this reason, the refrigerant storage container 1
The refrigerant in 7 is cooled and condensed, resulting in a pool of liquid refrigerant at an intermediate pressure.

Now, if the compressor 11 is stopped during this cooling operation, the on-off valve 19 is closed and intermediate-pressure liquid refrigerant is confined in the refrigerant storage container 17. The refrigerant circuit is in two states with the aperture 14 and the compressor 11 as boundaries: a low temperature/low pressure side including the indoor heat exchanger 15 and a high temperature/high pressure side including the outdoor heat exchanger 13. The refrigerant on the high pressure side flows into the low pressure side. This refrigerant movement is
This continues until the pressures on the high and low pressure sides are balanced, ensuring equalization.

Next, if the compressor 11 is restarted, the discharge pipe and suction pipe of the compressor 11 are connected to the throttle 14 while the compressor 11 is stopped.
Since the pressure is equalized by the movement of refrigerant through the refrigerant, it can be started reliably. At the same time as the compressor 11 is started, the on-off valve 19 is opened. Immediately after startup, the suction pressure (low pressure) of the compressor 11 is lower than during steady operation, and since the amount of refrigerant circulation is also small, the pressure loss due to the flow of refrigerant is also smaller than during steady operation. For this reason, the pressure at the connection point (point J) between the connecting pipe 18 and the refrigerant circuit is lower immediately after the compressor 11 is started than in a steady state. The liquid refrigerant in the refrigerant storage container 17 is thus forced into the refrigerant circuit and is fed through a part of the throttle 14 to the indoor heat exchanger 15 acting as an evaporator, where it is evaporated. For this reason, the compressor 11
Even immediately after starting up, refrigerant is supplied to the evaporator and cold air is quickly blown out.

As the operation continues further and becomes steady operation, the amount of refrigerant circulating also increases, and as described above, the refrigerant storage container 1
7, an intermediate-pressure liquid refrigerant accumulates.

The above explained the cooling operation, but during heating, the flow of refrigerant is as shown by the dotted arrow, and the indoor heat exchanger 15 operates as a condenser, and the outdoor heat exchanger 13 operates as an evaporator, but other functions are It is the same as when cooling.

〔Effect of the invention〕

As described above, in the present invention, the refrigerant storage container 17 is provided, and the liquid refrigerant at an intermediate pressure is stored in the container 17 during steady operation of the compressor 11, and the on-off valve 19 is closed even when the compressor is stopped. This state is maintained. The pressure balance between the discharge side and the suction side of the compressor 11 when the compressor is stopped is equalized by the throttle 14, so that no pressure difference occurs when the compressor is restarted. When restarting the compressor, taking advantage of the fact that the pressure at the connection point between the refrigerant storage container 17 and the refrigerant circuit is lower than the steady state,
By providing the on-off valve 19, the liquid refrigerant in the container is pushed out into the refrigerant circuit, and the liquid refrigerant is supplied to the evaporator immediately after startup. Therefore, this liquid refrigerant is evaporated in the evaporator, and the start-up performance can be improved. As a result, compressor 1
It has become possible to realize an air conditioner with good annual energy efficiency even if the number of starts and stops increases.

In addition, although the above example shows the case where it is applied to an air conditioner, other applications such as a refrigerator,
It can be implemented in a similar manner in refrigeration equipment and the like.

[Brief explanation of drawings]

Figures 1, 2, 3, and 5 are diagrams showing the characteristics of conventional air conditioners, Figure 4 is a diagram showing the refrigerant circuit of a conventional air conditioner, and Figure 6 is a diagram showing the characteristics of a conventional air conditioner. FIG. 2 is a refrigerant circuit diagram showing an example. 11... Compressor, 12... Four-way switching valve, 13...
...Outdoor heat exchanger, 14...Aperture, 15...Indoor heat exchanger, 16...Accumulator, 17...
Refrigerant storage container, 18...Connecting pipe, 19...Opening/closing valve, 20...Refrigerant piping.

Claims (1)

[Claims] 1. In a refrigeration cycle equipped with a refrigerant circuit in which refrigerant circulates through a compressor, a condenser, an aperture, and an evaporator in this order, the refrigerant circuit, including the aperture, reaches the evaporator at an appropriate position through a connecting pipe. A valve that connects refrigerant storage containers and exchanges heat between the refrigerant storage container and the suction pipe of the compressor, and that opens in the connection pipe and opens when the compressor starts and closes when the compressor stops. A refrigeration cycle characterized by being provided with.