JPH0578739B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a refrigeration system having a saturation temperature detection circuit.

(B) Prior art As shown in Fig. 10, in a conventional refrigeration system, high temperature and high pressure refrigerant discharged from a compressor a is led to a condenser c through a four-way valve b, where it exchanges heat with external heat. It becomes a high pressure condensate. The condensed liquid is throttled by an expansion valve d, becomes low temperature and low pressure, and is led to an evaporator e where it is evaporated. The refrigerant that has exchanged heat with external heat in the evaporator e is vaporized and reaches the suction side of the compressor a. Although a refrigeration cycle is thus formed, it is usually desirable to maintain the temperature of the gas on the suction side of the compressor a slightly higher than the saturation temperature of the suction pressure. Therefore, the temperature on the suction side of the compressor a is detected by the suction temperature detector h, and the saturation temperature of the suction pressure is detected by the saturation temperature detector i, and the temperature difference is detected by receiving these two signals. A regulator j adjusts the opening degree of the expansion valve d to maintain a proper refrigeration cycle by making the temperature on the suction side of the compressor a slightly higher than the saturation temperature of the suction pressure. The conventional method of finding the saturation temperature of this suction pressure is to
The high-pressure liquid refrigerant condensed by the capillary tube f is led to the suction side of the compressor a, where it is evaporated, and the saturation temperature corresponding to the suction pressure is detected.

(c) Problems to be solved by the invention In the conventional technology, the saturation temperature is detected by guiding the high-pressure liquid refrigerant condensed in the condenser to the suction side of the compressor through a capillary tube and evaporating it there. Was. This bypasses the high and low pressures of the refrigeration cycle, allowing the high pressure liquid to
Since the refrigerant is directly evaporated on the low-pressure side, a large amount of refrigerant is used to detect the saturation temperature, leading to a decrease in operating efficiency.Also, when the compressor is stopped, even if the expansion valve is closed, the refrigerant does not pass through the capillary tube. This movement causes refrigerant liquid to accumulate on the low pressure side, causing problems such as liquid compression when the compressor is started. The present invention has been made in view of the above, and is capable of detecting evaporator saturation temperature and condenser saturation temperature without directly guiding high-pressure liquid refrigerant to the low-pressure side and with a small amount of refrigerant, and is useful for controlling the refrigeration cycle. The first purpose is to provide high-pressure and low-pressure sides of the refrigerant circuit by tightening the expansion valve, and the second purpose is to solve problems caused by refrigerant movement during stoppage. That is.

(d) Means for Solving the Problems The present invention has been made in view of the problems described above, and includes a refrigeration system in which a compressor, a four-way valve, a condenser, an expansion valve, and an evaporator are connected in a ring. From the condenser inlet side, connect the condenser heat exchange part, the upper part of the condenser liquid reservoir part, the lower part of the condenser liquid reservoir part, and the condenser capillary tube in order, leading to the piping between the condenser outlet and the expansion valve inlet. From the condenser saturation temperature detection circuit configured as above, the piping between the expansion valve outlet and the evaporator inlet, the evaporator capillary tube, the lower part of the evaporator liquid reservoir,
It is an object of the present invention to provide a refrigeration system having an evaporator saturation temperature detection circuit configured to connect an upper part of an evaporator liquid storage part and an evaporator heat exchange part in sequence to reach the evaporator outlet side.

(E) Function Next, the function of this refrigeration system will be explained based on the basic circuit configuration diagram shown in FIG. Assuming that the refrigerant flow indicated by the solid arrow in the figure is a typical example of a refrigerant cycle, the high temperature and high pressure refrigerant discharged from the compressor 1 passes through the four-way valve 2, is led to the condenser 3, and is absorbed by external heat. It exchanges heat, becomes a high-pressure condensate, and reaches the outlet of the condenser 3. At this time, since the condenser saturation temperature detection circuit is connected in parallel between the inlet and outlet of the condenser 3, the condenser saturation temperature detection circuit also connects the four-way valve 2.
A high-temperature, high-pressure gas refrigerant branched from a pipe connecting the condenser 3 and the condenser 3 flows into the condenser 3. This refrigerant exchanges heat with external heat in the condenser heat exchange section 6, becomes a gas-liquid mixture, and flows from the upper part of the condenser liquid reservoir section 7.

A condenser capillary tube 8 is connected to the lower part of the condenser liquid reservoir 7, and the refrigerant in a gas-liquid mixed state flows out into a pipe connecting the condenser 3 and the expansion valve 4.

The flow rate of the refrigerant flowing through this condenser saturation temperature detection circuit is determined by the pressure between the inlet and outlet of the condenser saturation temperature detection circuit, the length and inner diameter of the condenser capillary tube 8,
and the dryness of the refrigerant flowing into the condenser capillary tube 8.

Further, the condenser capillary tube 8 has a large resistance when the refrigerant has a high degree of dryness, and has a small resistance when the refrigerant has a low degree of dryness. This has the effect of bringing the refrigerant staying in the condenser liquid reservoir 7 into a constant gas-liquid mixed state.

The temperature of the condenser liquid reservoir section 7 through which the refrigerant flows in and out while maintaining the gas-liquid mixed state in this manner indicates the saturation temperature of the condenser 3.

In addition, the high pressure liquid refrigerant condensed by the condenser 3 is
The gas is throttled by the expansion valve 4, becomes a low-temperature, low-pressure, gas-liquid mixed state, and flows into the evaporator 5, where it evaporates to become a gas and reaches the outlet of the evaporator 5.

At this time, the refrigerant in a gas-liquid mixed state that has been separated from the pipe connecting the expansion valve 4 and the evaporator 5 also flows into the evaporator saturation temperature detection circuit. This refrigerant passes through the evaporator capillary tube 9 and flows into the evaporator reservoir 10 from the lower part of the evaporator reservoir 10 .

The flow rate of the refrigerant flowing through this evaporator saturation temperature detection circuit is determined by the pressure between the inlet and outlet of the evaporator saturation temperature detection circuit, the length and inner diameter of the evaporator capillary tube 9,
and the dryness of the refrigerant flowing into the evaporator capillary tube 9.

Further, the refrigerant in a gas-liquid mixed state led to the evaporator capillary tube 9 is transferred to the evaporator liquid reservoir 1 having a diameter sufficiently larger than the inner diameter of the evaporator capillary tube 9.
0, the flow rate is extremely low, so that the refrigerant separates into gas and liquid, the liquid refrigerant accumulates at the bottom of the evaporator reservoir 10 due to its weight, and the gas refrigerant accumulates at the bottom of the evaporator reservoir 10. Move to the upper part of the liquid reservoir 10. When the liquid refrigerant accumulated in the lower part of the evaporator liquid reservoir 10 increases, it becomes a resistance to the refrigerant flowing into the evaporator liquid reservoir 10 from the evaporator capillary tube 9, and the inflow is suppressed. . This is the evaporator liquid reservoir section 1
This has the effect of keeping the amount of liquid refrigerant within 0 constant.

Further, since the evaporator heat exchange section 11 is connected to the upper part of the evaporator liquid reservoir section 10, the evaporator liquid reservoir section 10
The pressure inside is the same as the pressure inside the pipe connecting the evaporator 5 and the four-way valve 2, and the liquid refrigerant inside the evaporator reservoir 10 evaporates under the pressure inside the pipe, and the temperature of the evaporator reservoir 10 is , which indicates the evaporator saturation temperature. Further, the refrigerant at the outlet of the evaporator 5 passes through the four-way valve 2 and reaches the suction side of the compressor 1.

As described above, a refrigeration cycle is formed in which the refrigerant discharged from the compressor 1 circulates to the suction side of the compressor 1. The above explanation has been made regarding the refrigeration cycle in which the refrigerant flow is indicated by the solid line arrow in FIG. Although the functions constituting , and the refrigeration cycle are reversed, the operations are the same, and each saturation temperature detection circuit performs a reversible operation, so a description of the refrigeration cycle indicated by the broken line arrow will be omitted.

(F) Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings. FIG. This is a refrigerant circuit of an air conditioner, where solid arrows indicate refrigerant circulation during cooling operation, and dashed arrows indicate refrigerant circulation during heating operation. The expansion valve 4 is a reversible expansion valve equipped with a mechanism whose opening degree can be adjusted by an electric signal. FIG. 3 shows an example of an electric expansion valve, which is a type of expansion valve. The rotational movement of the screw 13 is converted into vertical movement by the screw. The tip of the drive screw 13 contacts the upper end of the valve 14 like a pivot bearing, and the vertical movement of the drive screw 13 opens and closes the valve 14. The valve 14 is airtightly assembled to a valve body 15 with a bellows 16.

In the refrigeration circuit configured as described above, the condenser heat exchange section 6 connected to the pipe connecting the four-way valve 2 and the condenser 3 is a bare, uninsulated conduit so as to exchange heat with external heat. , is placed in the same atmosphere as the external heat exchanging heat with the condenser 3.

When the high-temperature gas refrigerant discharged from the compressor 1 flows into the condenser heat exchange section 6, it exchanges heat with external heat, a part of the high-temperature gas is liquefied, and is connected to the condenser heat exchange section 6. It flows into the condenser liquid reservoir 7 from the upper part of the condenser liquid reservoir 7. As the amount of heat exchanged in the condenser heat exchange section 6 increases, the amount of refrigerant that is liquefied increases, and the amount of liquid refrigerant that flows into the condenser liquid reservoir section 7 also increases.

A condenser capillary tube 8 is connected to the lower part of the condenser liquid reservoir 7, and the condenser capillary tube 8 is connected to a pipe between the outlet of the condenser 3 and the inlet of the expansion valve 4. Therefore, condenser liquid reservoir section 7
The liquid refrigerant retained therein flows out through the condenser capillary tube 8 into the piping between the outlet of the condenser 3 and the inlet of the expansion valve 4.

At this time, the condenser capillary tube 8 has a small resistance to the liquid refrigerant and the flow rate of the refrigerant is large, but as the gas phase region in the refrigerant increases, the resistance of the condenser capillary tube 8 increases. Refrigerant flow rate decreases. Therefore, regardless of the amount of heat exchanged in the condenser heat exchange section 6, the refrigerant in the condenser reservoir section 7 is in a constant gas-liquid mixed state, and the temperature of the condenser reservoir section 7 is at the condenser saturation level. It will show the temperature.

Note that the high-temperature refrigerant intake of the condenser heat exchange section 6 may be taken out from a part of the distributor installed between the four-way valve 2 and the condenser 3, and the outlet of the condenser capillary tube 8 is connected to the condenser. It may be connected to a part of the distributor installed between the expansion valve 3 and the expansion valve 4.

Further, the refrigerant that has exited the expansion valve 4 is diverted to an evaporator capillary tube 9 connected to a pipe between the expansion valve 4 and the evaporator 5, and the refrigerant passes through the evaporator capillary tube 9 and passes through the evaporator capillary tube 9. The liquid flows into the liquid reservoir 10 from the lower part, and since the inner diameter of the evaporator liquid reservoir 10 is sufficiently larger than the inner diameter of the evaporator capillary tube 9,
The flow rate of the incoming refrigerant is extremely reduced, which causes the refrigerant to separate into gas and liquid, the liquid refrigerant accumulating at the bottom of the evaporator sump 10 due to its weight, and the gas refrigerant accumulating at the bottom of the evaporator sump 10. Move to the top of section 10.

When the liquid refrigerant accumulated in the lower part of the evaporator liquid reservoir 10 increases, it becomes a resistance to the refrigerant flowing into the evaporator liquid reservoir 10 from the evaporator capillary tube 9, and the inflow is suppressed. Ru.

This has the effect of keeping the amount of liquid refrigerant in the evaporator liquid reservoir 10 constant.

In addition, since the evaporator heat exchange section 11 is connected to the upper part of the evaporator liquid reservoir section 10, the evaporator liquid reservoir section 10
The pressure inside 0 is the same as the pressure inside the pipe connecting the evaporator 5 and the four-way valve 2, and the liquid refrigerant inside the evaporator reservoir 10 evaporates under the pressure inside the pipe, and the temperature of the evaporator reservoir 10 increases. represents the evaporator saturation temperature.

Note that the intake of the evaporator capillary tube 9 may be taken out from a part of the distributor installed between the expansion valve 4 and the piping of the evaporator 5, and the outlet of the evaporator heat exchange section 11 is connected to the evaporator 5. It may be connected to a part of the distributor arranged in the piping between the four-way valve 2 and the four-way valve 2.

Further, a condenser saturation temperature detector 13 that detects temperature using a thermistor or the like is closely connected to the condenser liquid reservoir 7, and generates an electric signal corresponding to the condenser saturation temperature.

Further, an evaporator saturation temperature detector 14 for detecting temperature using a thermistor or the like is closely connected to the evaporator liquid reservoir 10 to generate an electric signal corresponding to the evaporator saturation temperature.

In addition, on the suction side piping of the compressor 1, there is a suction gas temperature detector 15 that detects the temperature using a thermistor or the like.
in close contact with each other to generate an electrical signal corresponding to the intake gas temperature.

The signals of the condenser saturation temperature, evaporator saturation temperature, and intake gas temperature thus generated are input to the electric expansion valve drive circuit 12, and during the cooling operation shown by the solid line arrow, the evaporator saturation temperature detector By sending a signal from the electric expansion valve drive circuit 12 to the electric expansion valve 4 and opening and closing the valve of the electric expansion valve 4 so that the difference between the signal of the electric expansion valve 14 and the signal of the intake gas temperature detector 15 becomes constant. , performs super heat control.

Furthermore, during heating operation as indicated by the dashed arrow,
The evaporator 5 becomes a condenser, and the condenser 3 becomes an evaporator, and their functions are reversed and the flow of refrigerant is also reversed, so the signal from the condenser saturation temperature detector 13 becomes the evaporator saturation temperature signal, and the signal is Superheat control is performed in the same manner as described above so that the difference in the signals of the intake gas temperature detector 15 is constant.

FIG. 4 shows another embodiment, in which the condenser heat exchange section 6
By bringing the evaporator heat exchange section 11 and the evaporator heat exchange section 11 into close contact with each other and exchanging heat from each other, it also functions as a detection circuit without exchanging heat with external heat, and centralizes the condenser saturation temperature and evaporator saturation temperature. Since the saturation temperature detection circuit can be detected with the same temperature, the structure of the saturation temperature detection circuit can be simplified.

FIG. 5 shows another embodiment, in which a second evaporator heat exchange section 16 is provided between the pipe between the expansion valve 4 and the evaporator 5 and the pipe connecting the evaporator capillary tube 9. By bringing the second heat exchange section 16 into close contact with the high temperature section piping in the refrigeration circuit and heating the refrigerant flowing through the second evaporator heat exchange section 16, the dryness of the refrigerant is increased and the evaporator capillary is heated. This has the effect of suppressing the amount of refrigerant flowing through the tube 9 and making the amount of refrigerant flowing into the evaporator reservoir 10 appropriate.

FIG. 6 shows another embodiment in which the condenser capillary tube 8 is brought into close contact with the evaporator capillary tube 9, and the refrigerant flowing through the evaporator capillary tube 9 is heated by the condenser capillary tube 8. , increasing the dryness of the refrigerant and suppressing the amount of refrigerant flowing through the evaporator capillary tube 9;
This has the effect of optimizing the amount of refrigerant flowing into the evaporator liquid reservoir 10.

FIG. 7 shows another embodiment, in which a second heat exchange section 16 is provided between the pipe between the expansion valve 4 and the evaporator 5 and the pipe connecting the evaporator capillary tube 9,
By bringing the second heat exchange section 16 into close contact with the high temperature section piping in the refrigerant circuit and heating the refrigerant flowing through the second evaporator heat exchange section 16, the dryness of the refrigerant is increased and the evaporator carrier is heated. This has the effect of suppressing the amount of refrigerant flowing through the pillar tube 9 and making the amount of refrigerant flowing into the evaporator reservoir 10 appropriate.

FIG. 8 shows another embodiment, in which a second An expansion valve 17 is provided, and the pressure at the inlet of the second expansion valve 17 is adjusted according to the opening degree of the expansion valve 4 to perform appropriate superheat control. It is also free to extend the piping between the evaporator 5 and the four-way valve 2.

FIG. 9 shows another embodiment, in which a pipe is connected between the outlet of the evaporator saturation temperature detection circuit connected to the pipe between the outlet of the expansion valve 4 and the inlet of the evaporator 5, and the inlet of the evaporator 5. A second expansion valve 17 is provided, and the pressure at the inlet of the second expansion valve 17 is adjusted according to the opening degree of the expansion valve 4 to perform appropriate superheat control. It is also possible to extend the piping between the inlets of the two expansion valves 17 and further extend the piping connecting the evaporator 5 and the four-way valve 2.

(g) Effects of the Invention As is clear from the above explanation, the evaporator saturation temperature detector according to the present invention is provided with a liquid reservoir, which prevents wasteful liquid refrigerant from flowing out to the low pressure side, and further reduces the amount of liquid refrigerant. As for the refrigerant to be supplied to the reservoir, it is only necessary to replenish the amount of refrigerant that evaporates to the low pressure side. Therefore, the conventional high-pressure liquid refrigerant is injected directly to the low-pressure side,
Compared to the method of detecting saturation temperature by evaporation of liquid refrigerant, the amount of refrigerant is much smaller, and the amount of bypass by refrigerant used to detect saturation temperature during the refrigeration cycle can be suppressed, improving operational efficiency. . In addition, by making it possible to detect the condenser saturation temperature and evaporator saturation temperature, it is possible to know the state of the refrigerant in the refrigeration cycle.Using the detected condenser saturation temperature and evaporator saturation temperature, high pressure maintenance control, superheat It has a wide range of uses such as control. In addition, the condenser saturation temperature detection circuit and the evaporator saturation temperature detection circuit have the same configuration, and depending on the flow direction of the refrigerant, they function as either a condenser saturation temperature detection circuit or an evaporator saturation temperature detection circuit, so the saturation temperature The detection circuit can be easily configured. In particular, when using an electronic circuit such as a microcomputer as a control means, there is no need for a pressure transducer to determine the saturation temperature as an input to the electronic circuit, and the state of the refrigerant can be determined only by a temperature detector such as a thermistor. Therefore, the input to the electronic circuit is simplified. Furthermore, according to this invention, the refrigerant circuit can be completely separated into a high pressure side and a low pressure side with the expansion valve as the boundary, so by tightening the expansion valve, the evaporator side in particular remains in a low temperature state when the compressor is stopped. When the condenser side is at a high temperature, in addition to the movement of refrigerant to the evaporator side due to pressure equalization, there is also movement of refrigerant due to temperature.
This has a significant effect on proper operation of the refrigeration cycle, such as preventing the accumulation of liquid refrigerant on the evaporator side and causing liquid compression when the compressor is restarted.

[Brief explanation of the drawing]

FIG. 1 is a basic circuit diagram of the refrigeration system of the present invention.
FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention, FIG. 3 is a sectional view showing an example of the configuration of an electric expansion valve,
4 to 9 are circuit configuration diagrams showing other embodiments, and FIG. 10 is a circuit configuration diagram showing an example of a conventional configuration.

Claims (1)

[Claims] 1. In a refrigeration system in which a compressor, a four-way valve, a condenser, an expansion valve, and an evaporator are connected in a ring, from the condenser inlet side, a condenser heat exchange section, an upper part of a condenser liquid reservoir section, a condenser saturation temperature detection circuit configured to sequentially connect the condenser capillary tube to the lower part of the condenser liquid reservoir and reach the piping between the condenser outlet and the expansion valve inlet;
From the piping between the expansion valve outlet and the evaporator inlet, connect the evaporator capillary tube, the lower part of the evaporator liquid reservoir, the upper part of the evaporator liquid reservoir, and the evaporator heat exchange part in sequence, and reach the evaporator outlet side. A refrigeration system comprising an evaporator saturation temperature detection circuit configured as follows. 2. The refrigeration system according to claim 1, wherein the condenser heat exchange section in the condenser saturation temperature detection circuit and the evaporator heat exchange section in the evaporator saturation temperature detection circuit are brought into contact with each other. 3. The evaporator saturation temperature detection circuit further comprises a second evaporator heat exchange section between the piping between the expansion valve outlet and the evaporator inlet and the evaporator capillary tube. Refrigeration equipment. 4. The refrigeration system according to claim 2 or 3, wherein the condenser capillary tube in the condenser saturation temperature detection circuit and the evaporator capillary tube in the evaporator saturation temperature detection circuit are brought into contact with each other. 5. Claim 1, characterized in that a second expansion valve is provided between the outlet of the evaporator saturation temperature detection circuit connected to the pipe between the expansion valve outlet and the evaporator inlet and the expansion valve outlet. Refrigeration equipment as described. 6. Claim 2, characterized in that a second expansion valve is provided between the outlet of the evaporator saturation temperature detection circuit connected to the pipe between the expansion valve outlet and the evaporator inlet and the evaporator inlet. Or the refrigeration device according to 3 or 4.