JPH0771843A - Heat pump control device - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to prevent frost formation in an outdoor heat exchanger by providing a control valve in a heat pump device using a non-azeotropic mixed refrigerant. [Structure] Variable capacity compressor 1, 4-way valve 2, indoor heat exchanger 3, first expansion valve 4, gas-liquid separator 5, second expansion valve 6, and outdoor heat exchanger 7 are successively annularly arranged. Under the condition that frost is formed in the middle of the pipe that is connected to form the main circuit and that connects the gas side outlet of the gas-liquid separator 5 and the outlet of the outdoor heat exchanger 7 to the suction of the variable capacity compressor 1. 2-way valve that opens 9
It is provided with an injection circuit connected to.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump controller using a non-azeotropic mixed refrigerant.

[0002]

2. Description of the Related Art In recent years, mixed refrigerants have attracted attention as alternative refrigerants for heat pump devices due to regulations on CFCs and HCFCs. An example of a conventional heat pump device using a non-azeotropic mixed refrigerant will be described below with reference to the drawings.

FIG. 9 shows a refrigeration cycle of a heat pump device using a conventional non-azeotropic mixed refrigerant.

In FIG. 9, reference numeral 50 is a compressor, 51 is a four-way valve, 52 is an indoor heat exchanger, 53 is an expansion valve, and 54 is an outdoor heat exchanger, which are sequentially connected in a ring to form a main circuit. .

The operation of the heat pump device configured as described above will be described below.

The high-temperature and high-pressure refrigerant vapor compressed by the compressor 50 radiates heat in the indoor heat exchanger 52 via the four-way valve 51 and is condensed and liquefied. After that, the expansion valve 53 decompresses and expands into a low-temperature low-pressure refrigerant. And the outdoor heat exchanger 54
After absorbing heat, evaporating, and vaporizing, it becomes a low-temperature low-pressure refrigerant vapor, is compressed again by the compressor 50, and repeats the heat pump cycle (for example, JP-A-3-13766). At this time, a plate fin type heat exchanger as shown in FIG. 6 is generally used as the heat exchanger. In this heat exchanger, a large number of fins 62 are fixed to a heat transfer tube 61 at equal intervals, and air flows in the direction of arrow A with respect to the refrigerant flowing in the direction of arrow B.
It is configured to flow in directions and intersect each other vertically.

[0007]

However, in the heating operation, when a single refrigerant is used, as shown in FIG. 7, air at room temperature T _a exchanges heat at a stretch when passing through an outdoor heat exchanger (evaporator). Then, it becomes T _a1 and exits from the heat exchanger, whereas the non-azeotropic mixed refrigerant is saturated with the saturated liquid refrigerant temperature because the temperature of the phase change depends on the concentration even if the isobaric pressure changes as shown in FIG. Since the vapor refrigerant temperatures are different and the saturated liquid refrigerant temperature is lower than the saturated vapor refrigerant temperature, the heat exchange is performed with the air while the temperature rises, and the temperature difference ΔT between the air and the refrigerant is Is non-uniform at each value of the outdoor heat exchanger, and as a result, the temperature is the same in the case of a single refrigerant, but non-isothermal in the case of a non-azeotropic mixed refrigerant with a large boiling point difference between the low boiling point refrigerant and the high boiling point refrigerant. Becomes larger, the inlet refrigerant temperature is higher than the outlet refrigerant temperature. Also becomes low. Therefore, in the configuration as described above, when the outdoor temperature becomes considerably low during the heating operation, when the non-azeotropic mixed refrigerant is used even under the condition that the outdoor heat exchanger is not frosted with the single refrigerant, the outdoor heat exchanger is used. It had a problem of frost formation.

The present invention is intended to solve the above-mentioned problems of the conventional example and has an object to prevent frost formation on the outdoor heat exchanger.

[0009]

In order to solve the above problems, a control device for a heat pump device according to the present invention is a variable displacement compressor, a four-way valve, an indoor heat exchanger, a first expansion valve, a gas liquid. A main circuit in which a separator, a second expansion valve, and an outdoor heat exchanger are annularly connected, and a middle of a pipe from the gas-liquid separator gas side outlet and the outdoor heat exchanger outlet to the variable capacity compressor suction A refrigerating cycle having an injection circuit provided with a two-way valve, and compressor operating frequency detecting means for detecting and outputting the operating frequency of the variable displacement compressor during heating operation, and the operating frequency and the set frequency. And a first comparing means for outputting a control signal, an outdoor air temperature detecting means for detecting and outputting the outdoor air temperature, the outdoor air temperature and a set temperature are compared, and a control signal is output. Second comparison means and the outdoor An outdoor heat exchanger refrigerant temperature detection means for detecting and outputting a exchanger refrigerant temperature, third to the outdoor heat exchanger refrigerant temperature is compared with the set temperature, and outputs a control signal
Of the output mode of the storage means by the comparison means, the storage means that stores the output mode for controlling the opening and closing of the two-way valve, and the output signals generated from the first, second, and third comparison means. A control device for the heat pump device is provided, which comprises a selection means for selecting one of the two and an output means for opening and closing the two-way valve according to the output mode of the storage means.

[0010]

The present invention has the following functions due to the above-mentioned structure.

That is, the first expansion valve, the gas-liquid separator, and the first expansion valve are provided in the middle of the pipes leading to the indoor heat exchanger outlet and the outdoor heat exchanger inlet.
By providing a second expansion valve and providing an injection circuit having a two-way valve in the middle of the pipe from the gas-liquid separator gas side outlet and the outdoor heat exchanger outlet to the variable capacity compressor suction,
The refrigerant flowing out from the liquid side outlet of the gas-liquid separator changes state from (f) to (q) in FIG. 4 in the intermediate pressure state, and then the pressure drops to (h). Therefore, the temperature of the refrigerant at the inlet of the outdoor heat exchanger is about ΔT higher than that of the case where the injection circuit is not provided, and the temperature difference between the inlet and the outlet of the outdoor heat exchanger is smaller. Therefore, the non-isothermal property of the mixed refrigerant can be further reduced, and frost formation on the outdoor heat exchanger can be prevented.

[0012]

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

FIG. 1 is a refrigeration cycle diagram in the control device of the heat pump device of the present invention.

In FIG. 1, reference numeral 1 is a variable capacity compressor, 2
Is a 4-way valve, 3 is an indoor heat exchanger, 4 is a first expansion valve, 5 is a gas-liquid separator, 6 is a second expansion valve, 7 is an outdoor heat exchanger,
The circuits are sequentially connected in a ring to form a main circuit. A two-way valve 9 is provided in the middle of the injection circuit 8 that connects the gas-liquid separator gas side outlet and the pipe from the outdoor heat exchanger outlet to the variable capacity compressor suction.

FIG. 3 is an electric circuit diagram of the heat pump device shown in FIGS. In the figure, 21 is a power switch,
22 is a frequency detector for detecting the compressor operating frequency, 23 is a temperature detector for detecting the outdoor heat exchanger refrigerant temperature, 24 is a temperature detector for detecting the outdoor temperature,
Reference numeral 25 is an A / D converter, 26 is a microcomputer (hereinafter referred to as an LSI), an input circuit 27, a CPU 2
8, a memory 29, and an output circuit 30. The output of the frequency detector 22, the outdoor heat exchanger refrigerant temperature detector 23, and the outdoor temperature detector 24 is input to the input circuit 27 as A /
It is input via the D conversion device 25. Reference numeral 31 is an electromagnetic coil, which operates the opening and closing of the two-way valve 32 by the output of the output circuit 30.

The block diagram shown in FIG. 3 and the electronic control circuit shown in FIG. 2 will now be described. The frequency detector 2 shown in FIG.
Reference numeral 2 denotes compressor operating frequency detecting means for detecting and outputting the operating frequency of the compressor shown in FIG. 3, and the temperature detector 23 shown in FIG.
Is an outdoor heat exchanger refrigerant temperature detecting means for detecting and outputting the refrigerant temperature of the outdoor heat exchanger, and the temperature detector 24 of FIG. 2 is an outdoor air temperature detecting means for detecting and outputting the outdoor air temperature. Correspondingly, the LSI 26 of FIG. 2 compares the value detected by the compressor operating frequency detection means, the outdoor heat exchanger refrigerant temperature detection means, and the outdoor air temperature detection means with a set value and outputs a control signal. First and second
And the third comparing means, the storing means for storing the output mode for controlling the opening and closing of the two-way valve, and the output signals generated from the first, second and third comparing means, the output of the storing means It corresponds to a selecting means for selecting one of the modes. The electromagnetic coil 31 that opens and closes the two-way valve 32 in FIG. 2 corresponds to the output unit in FIG.

With the above structure, the structure and operation of the control circuit during operation of the heat pump device will be described with reference to FIG. FIG. 5 is a flowchart showing a program of the heat pump device stored in the memory 29 of the LSI 26. As can be seen from this flowchart, in the present invention, the two-way valve 9 is controlled to open only under the following conditions a) to c) that are considered to cause frost formation.

A) The compressor operating frequency f is f ₁ (eg 9
8)) b) When the outdoor air temperature T _r is lower than T ₁ (for example, 4 ° C.) c) When the outdoor heat exchanger refrigerant temperature T _e is lower than T ₂ (for example, 2 ° C.) Remote control, or When an operation instruction is issued due to forced operation, operation of the heat pump device starts. At the same time, step 40 shown in FIG. 5 is executed, the operating frequency is detected by the compressor operating frequency detecting means, and the value f and the rated frequency f ₁ are compared. If f> f ₁ , Y
The determination of "ES" is made, and step 41 is executed. f
If ≦ f ₁ , the process proceeds to step 44 by the determination of “NO”, the second output mode of the memory circuit is selected by the selection means built in the memory 29, the control signal is output from the output circuit 30, and the electromagnetic coil 31 is energized. Is stopped, the two-way valve 9 is closed, and the process returns to step 40. If T _r <T ₁ is determined by comparing the outdoor air temperature T _r with the set outdoor air temperature T ₁ , a “YES” determination is made, and the flow advances to step 43 to select the first of the memory circuits by the selection means incorporated in the memory 29. After the output mode is selected, a control signal is output from the output circuit 30 and the electromagnetic coil 31 is energized to open the two-way valve 9, and then the process returns to step 40.

Next, if f≤f ₁ , it is judged "NO" and the routine proceeds to step 42, where a comparison calculation between the outdoor heat exchanger refrigerant temperature T _e and the set refrigerant temperature T ₂ is performed, and T _e <T ₂ If so, a "YES" determination is made, the flow proceeds to step 43, the first output mode of the memory circuit is selected by the selection means built in the memory 29, an output is output from the output circuit 30, and the electromagnetic coil 31 is energized. After the one-way valve 9 opens, step 40
Return to.

If T _e ≧ T ₂ , the process proceeds to step 44 by the judgment of “NO”, the second output mode of the memory circuit is selected by the selecting means built in the memory 29, and the output circuit 3
A control signal is output from 0, the energization of the electromagnetic coil 31 is stopped, the two-way valve 9 is closed, and then the process returns to step 40.

A case will be described in which after the start of operation, none of the conditions a) to c) is satisfied. At this time, the control signal is output by the compressor operation detecting means, the outdoor air temperature detecting means, and the outdoor heat exchanger inlet refrigerant temperature detecting means of the LSI 26, and the second output mode of the memory circuit is selected by the selecting means incorporated in the memory 29. , Output circuit 30
Then, a control signal is output, the energization of the electromagnetic coil 31 is stopped, and the two-way valve 9 is closed. Therefore, under the conditions other than the conditions that may cause frost formation, the refrigerant flowing into the gas-liquid separator 5 does not flow through the injection circuit 8 but flows only through the main circuit.

Next, the case where the two-way valve 9 is opened again will be described. The two-way valve 9 is opened when the above conditions a) and b) are simultaneously satisfied, or when the above conditions a) and c) are simultaneously satisfied. At this time, the first output mode of the storage circuit is selected by the selection means built in the memory 29, an output is output from the output circuit 30, and the electromagnetic coil 31 is energized. As a result, the two-way valve 9 opens.

When the two-way valve 9 is opened, the refrigerant is the gas-liquid separator 5
Is separated into gas and liquid, the low boiling point rich vapor refrigerant flows through the injection circuit 8 and the high boiling point rich liquid refrigerant flows through the outdoor heat exchanger 7, so that the outdoor heat exchanger is more than the case without the injection circuit 8. The inlet temperature becomes higher,
By reducing the refrigerant temperature difference between the inlet and the outlet of the outdoor heat exchanger 7, it is possible to prevent frost formation on the heat exchanger 5.

[0024]

As is apparent from the above-described embodiment, the control device for the heat pump device of the present invention has the first expansion valve and the gas-liquid separator in the middle of the pipe leading to the indoor heat exchanger outlet and the outdoor heat exchanger inlet. By providing a second expansion valve and an injection circuit having a two-way valve in the middle of the pipe from the gas-liquid separator gas side outlet and the outdoor heat exchanger outlet to the variable capacity compressor suction, In the intermediate pressure state, the refrigerant flowing out of the separator liquid side outlet changes from (F) to (G) in FIG.
After that, the pressure drops and the process moves to (K). Therefore, the temperature of the refrigerant at the inlet of the outdoor heat exchanger is about ΔT higher than that when the injection circuit is not provided, and the temperature of the refrigerant at the inlet of the outdoor heat exchanger is smaller than that at the point of (k). Therefore, the non-isothermal property of the mixed refrigerant can be further reduced,
Frosting of the outdoor heat exchanger can be prevented.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram of a refrigeration system showing a first embodiment of the present invention.

FIG. 2 is a control circuit diagram embodying a control device of the device.

FIG. 3 is a block diagram in which the control device is represented by function realizing means.

FIG. 4 is a characteristic diagram showing the state of the refrigerant in each composition of the non-azeotropic mixed refrigerant.

FIG. 5 is a flowchart of the control device.

FIG. 6 is a schematic diagram of the overall configuration of a plate fin tube type heat exchanger.

FIG. 7 is a characteristic diagram showing a state of heat exchange of air temperature and refrigerant temperature at each heat transfer tube position when heat exchange is performed with a single refrigerant.

FIG. 8 is a characteristic diagram showing a state of heat exchange of air temperature and refrigerant temperature at each heat transfer tube position when heat exchange is performed with a non-azeotropic mixed refrigerant.

FIG. 9 is a refrigeration cycle diagram showing a conventional example.

[Explanation of symbols]

 1 Variable capacity compressor 2 4-way valve 3 Indoor heat exchanger 4 First expansion valve 5 Gas-liquid separator 6 Second expansion valve 7 Outdoor heat exchanger 8 Injection circuit 9 2-way valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Watanabe 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A variable capacity compressor, a four-way valve, an indoor heat exchanger, a first expansion valve, a gas-liquid separator, a second expansion valve, and an outdoor heat exchanger using a non-azeotropic mixed refrigerant. 2 in the middle of the main circuit connected in an annular shape and the pipe from the gas-liquid separator gas side outlet and the outdoor heat exchanger outlet to the variable capacity compressor suction
A refrigerating cycle having an injection circuit provided with a one-way valve is configured, and during heating operation, compressor operating frequency detecting means for detecting and outputting the operating frequency of the variable displacement compressor, and the operating frequency and frequency set value. And an outdoor air temperature detecting means for detecting and outputting the outdoor air temperature, a first comparing means for comparing the outdoor air temperature with a set temperature, and outputting a control signal. A second comparing means, an outdoor heat exchanger refrigerant temperature detecting means for detecting and outputting the outdoor heat exchanger refrigerant temperature, and comparing the outdoor heat exchanger refrigerant temperature with a set temperature, and outputting a control signal. Three
Of the output mode of the storage means by the comparison means, the storage means that stores the output mode for controlling the opening and closing of the two-way valve, and the output signals generated from the first, second, and third comparison means. A control device for a heat pump device, which comprises a selection means for selecting one of the two and an output means for opening and closing the two-way valve according to the output mode of the storage means.