JPS6323467B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a normal and reverse flow type thermoelectric expansion valve as the refrigerant throttling mechanism in the refrigeration circuit, thereby constructing a refrigeration cycle that is efficient in both heating and cooling operations. In addition, the purpose is to improve the rise characteristics.

Conventionally, refrigeration circuits have been constructed using thermoelectric expansion valves, but because these conventional thermoelectric expansion valves are unidirectional, they are used only in cooling-only equipment, and are not used in air-conditioning equipment. I couldn't help it.

As an example of a device using a conventional thermoelectric expansion valve, as shown in Fig. 1, a first thermocouple b is provided at the refrigerant inlet of an indoor heat exchanger a, and a second thermocouple c is provided at the outlet. The temperature difference between the two thermocouples b and c is maintained constant by controlling the opening degree of the thermoelectric expansion valve e through the control device d. There is a dedicated cooling device that controls the refrigeration circuit in this way.

With this configuration, when the flow path resistance due to the refrigerant in the indoor heat exchanger a is large, the difference in the saturation temperature of the refrigerant at the attachment parts of the thermocouples b and c is large, so the state of the refrigerant in the thermocouple c is adjusted appropriately. This makes it extremely difficult to accurately control the state of the refrigerant flowing into the compressor f.

Moreover, when attempting to construct a refrigeration circuit for an air conditioning system using this conventional thermoelectric expansion valve,
Since thermoelectric expansion valves were unidirectional, they had the disadvantage of requiring two thermoelectric expansion valves and two check valves, and furthermore, conventional thermoelectric expansion valves were only normally closed. Immediately after the start of operation, the thermoelectric expansion valve is in an extremely constricted state, and the flow rate of refrigerant is reduced.
It had drawbacks such as difficulty in maintaining good rise characteristics during cooling.

Therefore, the present invention provides a heating and cooling device that eliminates the above-mentioned conventional drawbacks, and one embodiment thereof will be described below with reference to FIGS. 2 to 4.

In Fig. 2, reference numeral 1 denotes a compressor, which connects an outdoor heat exchanger 3, a normal and reverse flow type thermoelectric expansion valve 4, and an indoor heat exchanger 5 through a cooling/heating switching valve 2 consisting of a four-way valve. It constitutes a refrigeration circuit connected to the 6 is a liquid receiver provided in the suction pipe 4 of the compressor. 8 is a thermistor attached to the outdoor heat exchanger 3, 9 is a thermistor attached near the center of the flow of the indoor heat exchanger 5, and 10 is a thermistor attached to the suction pipe 7. 11 is both thermistor 9, 10
This is a control device that controls the opening degree of the thermoelectric expansion valve 4 in response to a signal from the thermoelectric expansion valve 4.

Next, the structure of the thermoelectric expansion valve 4 will be explained with reference to FIG. 3.The thermoelectric expansion valve 4 consists of a valve portion 12 and a valve driving portion 13. The valve part 12 is the valve frame 1
4 and a valve body 15. The valve frame 14 is the valve seat part 16
an inflow/outflow port 17 through which fluid flows in and out;
18, and refrigerant pipes 19 and 20 are connected to each port 17 and 18, respectively. The valve body 15 consists of two connected upper and lower members 21 and 22, and passages 23 and 24 are formed in these members 21 and 22 to communicate the port 18 side and the inside of the valve driving portion 13. A check valve 25 is provided between the passages 23 and 24 to prevent the refrigerant from flowing from the passage 24 to the passage 23. Note that the valve body 15 is provided in a hole 26 formed in the valve frame 14 so as to be vertically slidable. On the other hand, the valve driving portion 13 forms a sealed space 29 with the upper casing 27, the lower casing 28, and the valve frame 14. Two bimetals 30 and 31 are housed in this space 29, and both bimetals 30 and 31 are arranged in parallel at both ends with spacers 32 and 33 interposed therebetween.
Then, a hole 3 is provided in the center of both bimetals 30 and 31.
4 and 35 are bored and fixed to the center of the inner surface of the upper casing 27. The support pin 36 is inserted into the hole 41 of the upper bimetal from above, and the pin portion 37 formed at the upper end of the valve body 15 is inserted into the lower bimetal. 31 hole 3
5 from below, both bimetals 30 and 31 are supported within the space 29. Note that the valve body 14 is always urged upward by a spring 39 via a washer 38. 40 is an electric heater that forcibly heats the upper bimetal 30, and is wound around the upper bimetal 30. The upper bimetal 30 normally maintains the valve portion 12 in a substantially fully open state, and when heated by the electric heater 40, bends and acts to narrow the valve portion 12. Terminals 41 and 42 are connected to both ends of the electric heater 40 and are provided through the upper casing 27. Furthermore, the bimetal 30 is forcibly heated by the electric heater 40, so that
Both ends are deformed so as to move downward (in the direction of arrow A in the figure). Therefore, when the electric heater 40 is energized, the upper bimetal 30 deforms and pushes the valve body 15 upward against the elastic force of the spring 39, reducing the gap between the valve seat 16 and the lower end of the valve body 15. . In other words, it acts in a direction to throttle the valve. The degree of aperture of the valve in this case is adjusted by the amount of power supplied to the electric heater 40. That is, when a large amount of electric power is passed through the upper bimetal 30, the upper bimetal 30 is greatly deformed and curved, and the degree of restriction of the valve increases. In other words, the opening degree becomes smaller. Conversely, when the electric power to the electric heater 40 is small, the amount of deformation of the upper bimetal 30 is small;
The degree of restriction of the valve is small. In addition, the lower bimetal 31
is a bimetal for load condition compensation, and deforms under the influence of the refrigerant flowing into the space 29 from the sliding surface between the hole 26 and the valve body 15 and the temperature of the surrounding air. The thermoelectric expansion valve 4 is a forward and reverse flow type expansion valve, and the refrigerant flows into the port 17 through the port 17 and passes through the constriction formed between the valve body 15 and the valve seat 16. Of course, it flows out from port 1, and vice versa.
It is also possible for the liquid to flow in from port 8 and flow out through port 17 through a constriction formed between valve body 15 and valve seat 16 . Note that when the pressure on the port 17 side becomes high and the pressure on the port 18 side becomes low, a part of the refrigerant flows into the space from the sliding surface between the valve body 15 and the hole 26, but this flowed refrigerant
Port 1 through passages 23, 24 and check valve 25
It flows to 8 and does not accumulate in the space. Conversely, when the pressure on the port 18 side becomes higher than that on the port 17 side, the check valve 25 closes and almost no refrigerant flows into the space 29.

Next, the operation of the above structure will be explained.
First, cooling operation will be explained. When the compressor 1 is operated with the cooling/heating switching valve 2 in the state shown in the figure, the refrigerant flows as shown by the solid arrow in Figure 2, and the compressor 1
The high-temperature, high-pressure gas refrigerant discharged from the cooling/heating switching valve 2 is cooled by the outdoor heat exchanger 3, further depressurized by the thermoelectric expansion valve 4, and flows into the indoor heat exchanger 5.

It is heated in the indoor heat exchanger 5 and becomes a low-pressure gas refrigerant, which passes through the cooling/heating switching valve 2 and is sucked into the compressor 1 via the liquid receiver 6.

When the above refrigerant circuit is operated, the indoor heat exchanger 5
The thermistor 9 attached to the suction pipe 7 and the thermistor 10 attached to the suction pipe 7 exhibit electrical resistance values corresponding to the refrigerant temperature at their respective attachment positions.

The control device 11 detects the difference between the electric resistance values of the two thermistors 9 and 10 and a predetermined value, and applies a voltage corresponding to the detected difference to the electric heater of the thermoelectric expansion valve 4. 40.

In other words, if the difference between the electrical resistance values of the two thermistors 9 and 10 is smaller than a predetermined value, the voltage applied to the electric heater 40 of the thermoelectric expansion valve 4 is increased, and the amount of heating by the electric heater 40 is increased. By increasing the size, the valve body 16 is moved downward and the valve opening is decreased, thereby reducing the refrigerant flow rate. This operation causes the temperature of the refrigerant in the thermistor 10 to rise, and the difference in electrical resistance between the thermistors 9 and 10 to increase. If the difference between the electrical resistance values of both thermistors 9 and 10 is larger than a predetermined value, conversely, by lowering the voltage applied to the electric heater 40,
By moving the valve body 15 upward and increasing its opening degree, the refrigerant flow rate is increased. This operation lowers the refrigerant temperature in the thermistor 10 and reduces the difference in electrical resistance between the thermistors 9 and 10.

By repeating the above operation until the electrical resistance value of both thermistors 9 and 10 reaches a predetermined value, the electrical resistance of the mounting part of the two thermistors 8 and 9 can be maintained even when the load changes. The temperature difference, that is, the difference in refrigerant temperature, can be kept constant, and the state of the refrigerant flowing into the compressor 1 can be controlled, which allows for more appropriate cooling operation and protects the compressor 1 from a temperature standpoint. It can be carried out.
The thermistor mounting position will be explained with reference to FIGS. 2 and 4. Since FIG. 2 is as described above, the explanation will be omitted and FIG. 4 will be explained.

FIG. 4 is a model showing the phase state of the refrigerant in the indoor heat exchanger 5 during cooling operation.
The thermistor 9 is installed in the indoor heat exchanger 5 at a position in the gas/liquid multiphase region. The shaded area 44 represents liquid refrigerant, and 45 represents gas refrigerant. 46 is an inlet portion of the indoor heat exchanger 5, and 47 is an outlet portion thereof.

During cooling operation, the multiphase refrigerant with a high liquid content that has exited the thermoelectric expansion valve 4 flows in the direction of the arrow in FIG. The refrigerant becomes a multiphase refrigerant, becomes a gas refrigerant at position 43, is further superheated, and flows out from the outlet section 47 to the cooling/heating switching valve 2 and the liquid receiver 6.
It flows into the compressor 1 via.

When the above-mentioned refrigeration circuit is configured, the thermistor 9 of the indoor heat exchanger 5 can detect the saturation temperature of the refrigerant at the attachment part, and the value is close to the saturation temperature of the refrigerant at the outlet part 47. If the flow resistance of the refrigerant from the suction pipe 7 to the thermistor 10 is not large, the value will be close to the saturation temperature of the refrigerant at the mounting position of the thermistor 10. From this, the refrigerant state in the suction pipe 7 can be detected more accurately based on the temperature difference between the thermistors 9 and 10.
The state of the refrigerant flowing into the compressor 1 can be controlled more accurately, and appropriate cooling operation can be performed. Control is also easy.

Next, the mounting position of the thermistor 9 will be explained. As is well known, in a refrigeration cycle, when the heat load changes, the state of the refrigerant in the refrigeration circuit components also changes.

Since the state of the refrigerant in the indoor heat exchanger 5 also changes during cooling operation, the position 43 in the indoor heat exchanger 5, which is entirely a gas region, also moves.

The mounting position of the thermistor 9 of the indoor heat exchanger 5 is set in the heat exchanger 5 throughout the cooling operation range,
If the position is always in the gas-liquid multiphase region and close to the gas single-phase region (for example, the position set at maximum load), the refrigerant will always be in the gas-liquid state even if the heat load fluctuates over a wide range. It is a multiphase region and the phases are constant, so the saturation temperature of the refrigerant at that position can always be detected. Therefore, the state of the refrigerant flowing into the compressor 1 is always correctly detected by the thermistor 9 of the indoor heat exchanger 5 and the thermistor 10 of the suction pipe 7, and is controlled more accurately to perform the appropriate cooling operation. be able to.

If the thermistor 9 is installed near the outlet 47, the thermistor 9 will detect the temperature in the gas/liquid mixed phase region or the gas region depending on the fluctuation of the heat load, and the phase to be detected will be constant. Without,
There may be cases where the state of the refrigerant in the suction pipe 7 cannot be properly detected based only on the temperature relationship with the thermistor 10 provided in the suction pipe 7. In other words, sending incorrect information to the control device 11 of the thermoelectric expansion valve 4 may cause the thermoelectric expansion valve 4 to malfunction, or its operation may become unstable, significantly reducing the control range for thermal load fluctuations. It will be very limited.

In addition, during heating operation, the refrigerant passes through the compressor 1, the cooling/heating switching valve 2, the indoor heat exchanger 5, the forward/reverse flow type thermoelectric expansion valve 4, the outdoor heat exchanger 3, the cooling/heating switching valve 2, and the liquid receiver 6 in order. The flow enters the compressor in the direction of the dashed arrow shown in the figure.

The state of the refrigerant in the refrigerant circuit and the control of the thermoelectric expansion valve 4 are the same as in the cooling operation by replacing the indoor heat exchanger 5 with the outdoor heat exchanger 3 and replacing the thermistor 9 with the thermistor 10 in the explanation for cooling operation. The effect will be the same.

Note that the thermoelectric expansion valve 4 is a normally open type, that is, the valve portion 12 is kept fully open when the electric heater 40 is not energized, so that the start-up characteristics of the cooling operation can be maintained very well. . That is, immediately after the start of operation, the thermoelectric expansion valve 4 is almost fully open, so a large amount of refrigerant flows into the indoor heat exchanger, allowing quick startup and maintaining good startup characteristics. In addition, after startup is completed and stable operation is reached,
As already mentioned, the opening of the thermoelectric expansion valve 4 is adjusted according to the load based on the signals from the thermistor 8 or 9 and 10. In addition, in the case where the control device 11 breaks down for some reason,
Even if the compressor 1 is operated without knowing this, since the thermoelectric expansion valve 4 is almost fully open, the compressor will not be adversely affected. In addition, by cutting off the power to the electric heater 40 at the same time as the compressor 1 stops operating, the thermoelectric expansion valve 4 is almost fully open, so the height balance in the refrigeration circuit can be achieved in an extremely short time, and compared to the conventional method. There is no need to wait for a predetermined period of time (usually 3 minutes) until the compressor 1 is restarted.

Next, another embodiment of the present invention will be described with reference to FIG.

In this embodiment, the thermistor 10 of the suction pipe 7 in FIG. 2 in the previous embodiment is installed between the heat exchanger 5 or 3, which serves as an evaporator during cooling and heating operations, and the cooling/heating switching valve 2. Components that are the same as those in FIG. 2 are given the same numbers and their explanations are omitted.

In FIG. 5, 48 is a thermistor installed in the refrigerant circuit 49 between the outdoor heat exchanger 3, which serves as an evaporator during heating operation, and the cooling/heating switching valve 2, and 50 indicates an indoor heat exchanger, which serves as an evaporator during cooling operation. This is a thermistor installed in the refrigerant circuit 51 between the heating and cooling switching valve 2.

The operation of this embodiment uses a thermistor 50 to control the thermoelectric expansion valve 4 during heating operation, and a thermistor 49 during heating operation, instead of the thermistor 10 of the suction pipe 7 explained in the previous embodiment. The thermoelectric expansion valve 4 is controlled by the thermoelectric expansion valve 4, and the same effects as in the previous embodiment can be obtained.

As described above, in the present invention, the detector provided in the suction pipe portion may be provided at any position between the heat exchanger serving as the evaporator and the compressor.

As is clear from the above embodiments, the present invention forms a refrigeration circuit by connecting an outdoor heat exchanger, a forward/reverse flow type thermoelectric expansion valve, and an indoor heat exchanger to a compressor via a cooling/heating switching valve in an annular manner. By providing a detector for controlling the thermoelectric expansion valve in the indoor heat exchanger, the outdoor heat exchanger, and the suction part to the compressor,
It has the advantage that the refrigerant flowing into the compressor can be easily controlled in both cooling and heating operations, and that appropriate cooling and heating operations can be performed and the temperature of the compressor can be protected. Moreover, since the thermoelectric expansion valve of the present invention is a normally open type, it can maintain good rise characteristics especially during cooling, and can open the conventional normally closed thermoelectric expansion valve in both cases of cooling and heating. Immediately after starting operation,
Although it was necessary to provide a thermoelectric expansion valve and a means for forcibly opening the valve, the present invention eliminates the need for such means and simplifies control during startup. moreover,
Even if the current supply circuit to the thermoelectric expansion valve stops working for some reason, the thermoelectric expansion valve is in an open state, so there will be no adverse effect on the compressor.

In addition, the position of the detector attached to the indoor heat exchanger and the outdoor heat exchanger should always be set near the position where the refrigerant in the indoor heat exchanger is in the gas single-phase region during cooling, and the position in the gas-liquid multiphase region. During heating, the refrigerant in the outdoor heat exchanger is always located near the position where it is in the gas single-phase region and in the gas-liquid multiphase region, so that the refrigerant can be maintained even against wide-ranging heat load fluctuations. The mounting part of the detector is always in a gas/liquid multiphase region, and stable phase conditions can be detected.
Therefore, by using it in conjunction with a detector installed in the suction part, the refrigerant state in the suction part can be detected accurately at all times, and the refrigeration cycle can be accurately controlled even over a wide range of heat load fluctuations. It has the advantage of being able to perform appropriate heating and cooling operations.

[Brief explanation of the drawing]

Figure 1 is a schematic refrigeration circuit diagram of a conventional heating and cooling system.
Fig. 2 is a schematic refrigeration circuit diagram of an air conditioning system according to an embodiment of the present invention, Fig. 3 is a cross-sectional view of a forward and reverse flow type thermoelectric expansion valve used in the air conditioning system, and Fig. 4 is a diagram of a refrigeration circuit in an indoor heat exchanger. An explanatory diagram showing a model of the phase state of a refrigerant,
FIG. 5 is a schematic refrigeration circuit diagram of a heating and cooling system according to another embodiment of the present invention. 1...Compressor, 2...Cooling/heating switching valve, 3...Outdoor heat exchanger, 4...Thermoelectric expansion valve, 5...Indoor heat exchanger,
8, 9, 10...Thermistor (detector), 11...Control device, 12...Valve portion, 13...Valve drive portion, 15
...Valve body, 30...Upper bimetal, 40...Electric heater.

Claims (1)

[Claims] 1 A refrigeration circuit is formed by connecting an outdoor heat exchanger, a thermoelectric expansion valve, and an indoor heat exchanger to a compressor via a cooling/heating switching valve in an annular manner, and the thermoelectric expansion valve is connected to a forward/reverse valve part and a valve. The valve driving part is provided with a bimetal that operates a valve body provided in the valve part to change the degree of restriction of the valve, and an electric heater that heats and deforms this bimetal, and detects the state of the refrigerant. Temperature detectors that emit signals for controlling the power supplied to the electric heater are provided in the indoor heat exchanger, the outdoor heat exchanger, and the suction section to the compressor, respectively, and the temperature detectors are arranged to control the temperature of the indoor heat exchanger. The detector is installed at a gas-liquid multiphase region near the position where the refrigerant in the indoor heat exchanger becomes a gas single-phase region during cooling, and the outdoor heat exchanger is installed at a location near the location where the refrigerant in the indoor heat exchanger becomes a gas single-phase region during heating. A heating and cooling system characterized in that the refrigerant in the exchanger is located in a gas-liquid multiphase region near a position where the gas is in a single-phase region.