JPH0763430A - Saturated vapor temperature detection circuit of refrigeration cycle - Google Patents

Abstract

PURPOSE:To accurately detect the saturated vapor temperature of the refrigerant sucked into the compressor without complicating the constitution of the refrigeration cycle relating to a refrigeration cycle using a nonazeotropic refrigerant. CONSTITUTION:There is provided a bypass 5 one end of which is connected to a conduit connecting the outlet of a condenser 2 to a motor-operated expansion valve 3 and the other end of which is connected to a conduit connecting the outlet of a vaporizer 4 to the inlet of a compressor 1. To this bypass 5 there are provided, in sequence from the upstream side, an auxiliary throttle 6, a heater 7, and a temperature sensor 8. The equipment furthermore includes a heater-controlling circuit 10 for controlling the amount of heating by the heater 7 and a saturated vapor temperature-calculating circuit 11 which detects the temperature of the refrigerant periodically as prescribed by means of the temperature sensor 8 and judges the saturated vapor temperature from the detected changes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a saturated vapor temperature detection circuit for a refrigeration cycle using a non-azeotropic mixed refrigerant in which two or more kinds of refrigerants having different boiling points are mixed at a predetermined ratio.

[0002]

2. Description of the Related Art In recent years, from the standpoint of protecting the global environment, regulations on CFCs that destroy the ozone layer have been strengthened, and it has been decided to abolish CFC (chlorofluorocarbon), which has a particularly high destructive power, at the end of 1995. Also, regarding the FCFC (hydrochlorofluorocarbon), which has a relatively small destructive power, the total amount regulation was started in 1996, and it has been decided that it will be completely abolished in the future. Therefore, for devices that use CFCs as refrigerants, alternative refrigerants are being developed, and HFCs (hydrofluorocarbons) that do not destroy the ozone layer are being studied, but HCFCs used in refrigerators and air conditioners are being investigated. No substitute refrigerant that can be used alone as a substitute refrigerant is found in HFC, and therefore, a non-azeotropic mixed refrigerant obtained by mixing two or more kinds of HFC refrigerants is considered promising.

Conventionally, a refrigeration cycle such as a refrigerator or an air conditioner using a single refrigerant such as CFC or HCFC has a COP
In order to improve the (coefficient of performance) and ensure the reliability of the compressor, superheat control was performed, and for that purpose, a saturated steam temperature detection circuit was provided.

A conventional saturated vapor temperature detecting circuit will be described below with reference to the drawings. FIG. 9 is a refrigeration cycle diagram of a conventional refrigerator, air conditioner, or the like. In the figure, 1 is a compressor, 2 is a condenser, 3 is an electric expansion valve whose valve opening can be pulse-controlled by using a stepping motor, 4
Are evaporators, which are in turn connected in a ring.
Reference numeral 5 denotes a bypass circuit having one end connected to a pipe line connecting the condenser 2 and the electric expansion valve 3 and the other end connected to a pipe line connecting the evaporator 4 and the compressor 1. Is provided with an auxiliary aperture 6. Further, temperature sensors 8 and 9 are provided on the bypass circuit 5 and the suction-side pipelines of the compressor 1, respectively, and the valve opening calculation circuit 12 electrically drives the temperature sensors 8 and 9 based on the temperatures detected by the temperature sensors 8 and 9. The valve opening degree of the expansion valve 3 is calculated, a valve opening degree signal is sent out, and the expansion valve drive circuit 13 receives the valve opening degree signal to control the valve opening degree of the electric expansion valve 3.

FIG. 10 shows this refrigeration cycle on the P-h (Moriel) diagram.
The points of symbols B and C show the states of the refrigerant at the positions A, B and C in FIG. As is clear from the figure, since the point C is in the gas-liquid two-phase state, the temperature of the refrigerant is the saturated vapor temperature TS of the refrigerant at the point B. Therefore, the difference (T2-TS) between the temperature TS detected by the temperature sensor 8 and the temperature T2 detected by the temperature sensor 9 represents the superheat amount ΔT of the refrigerant sucked into the compressor 1.

Next, the control of this refrigeration cycle will be described. FIG. 11 is a diagram showing the relationship between the superheat amount ΔT and the valve opening change amount of the electric expansion valve 3, which is based on the temperature signals TS and T2 detected by the temperature sensors 8 and 9 at a predetermined cycle. The calculation circuit 12 calculates the superheat amount ΔT, and FIG.
The valve opening signal of the electric expansion valve 3 is expanded according to the relationship shown in 1 (when the superheat amount ΔT is larger than the set value, the valve opening is increased, and when the superheat amount ΔT is smaller than the set value, the valve opening is decreased). It is sent to the valve drive circuit 13, and the expansion valve drive circuit 13
The valve opening of the electric expansion valve 3 is controlled to maintain the superheat amount ΔT at the set value.

[0007]

However, the conventional saturated vapor temperature detection circuit for the refrigeration cycle has the following problems.

FIG. 12 shows a refrigeration cycle in the case of using a non-azeotropic mixed refrigerant as a refrigerant on the Ph (Mollier) diagram, and the points of symbols A, B and C in the same figure are shown. 9 shows the state of the refrigerant at positions A, B and C in FIG. Here, the amount of super heat at point B is
It can be determined by the difference between the temperature at point B and the saturated steam temperature (point E). Here, in the case of a single refrigerant, the temperature at point C is the same as the saturated vapor temperature as shown in FIG. 10, but in the case of a non-azeotropic mixed refrigerant, as shown in FIG. Since the line is a line descending to the right, the temperature at point C is lower than the temperature at the saturated steam temperature (point E). Therefore, ΔT calculated from the temperature signals T1 and T2 detected by the temperature sensors 8 and 9 becomes a value larger than the true superheat amount, and in this state, the refrigerant is controlled to maintain the set value. It is sucked into the compressor when the actual amount of superheat is lower than the set value or in the state of wet steam.

Therefore, there is a possibility that the reliability of the compressor may be lowered and the COP may be lowered due to the liquid compression.

In view of the above problems, the saturated vapor temperature detection circuit of the refrigeration cycle of the present invention is a refrigeration cycle using a non-azeotropic mixed refrigerant, and the saturated vapor temperature of the refrigerant sucked into the compressor without complicating the structure of the refrigeration cycle. The purpose of this is to accurately detect the refrigeration cycle and thereby to realize optimal refrigeration cycle control.

[0011]

In order to solve the above problems, a saturated vapor temperature detection circuit of a refrigerating cycle according to the present invention is a non-azeotropic mixture in which two or more kinds of refrigerants having different boiling points are mixed at a predetermined ratio as refrigerants. Using a refrigerant, a compressor, a condenser, a decompressor, and an evaporator are sequentially connected by a pipe in a ring shape to form a refrigerant circuit, and one end is connected to a conduit from the condenser outlet to the decompressor outlet, and the other end. A bypass circuit is connected to the pipeline from the evaporator outlet to the compressor inlet, and an auxiliary decompressor, refrigerant heating means, and refrigerant temperature detection means are provided in this bypass circuit in order from the upstream side to heat the refrigerant heating means. The heating amount control means for controlling the amount, the refrigerant temperature detecting means for detecting the refrigerant temperature in a predetermined cycle, and the judging means for judging the saturated vapor temperature based on the change amount.

A saturated vapor temperature detection circuit of another refrigeration cycle of the present invention uses a non-azeotropic mixed refrigerant in which two or more kinds of refrigerants having different boiling points are mixed at a predetermined ratio as the refrigerant.
A compressor, a condenser, a decompressor, and an evaporator are sequentially connected by a pipe in a ring shape to form a refrigerant circuit, one end of which is connected to a conduit from the condenser outlet to the decompressor outlet, and the other end is connected to the evaporator outlet. A bypass circuit connected to the pipeline from the compressor to the compressor inlet is provided, and an auxiliary pressure reducer and a refrigerant temperature detecting means for varying the pressure reduction amount are provided in this bypass circuit in order from the upstream side, and a refrigerant temperature detecting means is provided from the auxiliary pressure reducer outlet. Decompression amount control means for controlling a decompression amount of the auxiliary decompressor by heat-exchangeably connecting a part of a pipe reaching the installation position and a part of a pipe extending from the compressor outlet to the condenser inlet, The refrigerant temperature detecting means detects the refrigerant temperature in a predetermined cycle and has a judging means for judging the saturated vapor temperature from the amount of change.

A saturated vapor temperature detecting circuit of another refrigeration cycle of the present invention uses a non-azeotropic mixed refrigerant in which two or more kinds of refrigerants having different boiling points are mixed at a predetermined ratio as the refrigerant.
A compressor, a condenser, a decompressor, and an evaporator are sequentially connected by a pipe in a ring shape to form a refrigerant circuit, one end of which is connected to a conduit from the condenser outlet to the decompressor outlet, and the other end is connected to the evaporator outlet. A bypass circuit connected to the pipeline from the compressor to the compressor inlet is provided, and an auxiliary pressure reducer and a refrigerant temperature detecting means for varying the pressure reduction amount are provided in this bypass circuit in order from the upstream side, and a refrigerant temperature detecting means is provided from the auxiliary pressure reducer outlet. A part of the pipeline leading to the installation position is arranged in the evaporator, and the pressure reduction amount control means for controlling the pressure reduction amount of the auxiliary pressure reducer and the refrigerant temperature detection means detect the refrigerant temperature in a predetermined cycle and the change thereof. It has a discriminating means for discriminating the saturated vapor temperature from the amount.

[0014]

The present invention has the following actions due to the above means.

That is, a bypass circuit having one end connected to a conduit from the condenser outlet to the decompressor outlet and the other end connected to a conduit from the evaporator outlet to the compressor inlet is provided. Auxiliary decompressor, refrigerant heating means, refrigerant temperature detection means are provided in order from the upstream side, the heating amount control means for controlling the heating amount of the refrigerant heating means, the refrigerant temperature is detected by the refrigerant temperature detection means in a predetermined cycle, and its change amount By having a determination unit that determines the saturated vapor temperature more, in a refrigeration cycle using a non-azeotropic mixed refrigerant, it is possible to accurately detect the saturated vapor temperature of the compressor suction refrigerant without complicating the configuration of the refrigeration cycle. This makes it possible to realize optimum refrigeration cycle control.

Further, a bypass circuit having one end connected to a pipe line extending from the condenser outlet to the pressure reducer outlet and the other end connected to a pipe line extending from the evaporator outlet to the compressor inlet is provided. Auxiliary decompressor with variable decompression amount and refrigerant temperature detecting means are provided in order from the upstream side, and a part of a pipe line from the auxiliary decompressor outlet to the refrigerant temperature detecting means installation position and a pipe from the compressor outlet to the condenser inlet Heat exchange connection with part of the path,
By having a decompression amount control means for controlling the decompression amount of the auxiliary decompressor, a refrigerant temperature detecting means for detecting the refrigerant temperature in a predetermined cycle and having a judging means for judging the saturated vapor temperature from the change amount thereof, Since the heat can be utilized, the saturated vapor temperature of the compressor suction refrigerant can be accurately detected without newly adding a heating means, and thus optimal refrigeration cycle control can be realized.

Further, a bypass circuit having one end connected to a pipeline from the condenser outlet to the decompressor outlet and the other end connected to a pipeline from the evaporator outlet to the compressor inlet is provided. Auxiliary decompressor with variable decompression amount and refrigerant temperature detecting means are provided in order from the upstream side, and a part of the pipeline from the outlet of the auxiliary decompressor to the installation location of the refrigerant temperature detecting means is arranged in the evaporator, and the auxiliary decompressing By having a decompression amount control means for controlling the decompression amount of the container and a determination means for detecting the refrigerant temperature at a predetermined cycle by the refrigerant temperature detection means and determining the saturated vapor temperature from the amount of change, heat exchange with a high temperature heating source Since the refrigerant in the bypass circuit can be turned into superheated steam without doing so, it is possible to accurately detect the saturated vapor temperature of the compressor suction refrigerant in a short time, and thereby achieve optimal refrigeration cycle control. it can.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that components having the same functions as those described in the section of the related art are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 1 is a refrigeration cycle diagram in the first embodiment of the present invention. In the figure, 1 is a compressor, 2 is a condenser, 3 is an electric expansion valve, and 4 is an evaporator, which are sequentially connected in an annular shape and use a non-azeotropic mixed refrigerant as a refrigerant. Reference numeral 5 denotes a bypass circuit having one end connected to a pipe line connecting the condenser 2 and the electric expansion valve 3 and the other end connected to a pipe line connecting the evaporator 4 and the compressor 1. Is provided with an auxiliary aperture 6. A heater 7 for heating the refrigerant is attached downstream of the auxiliary throttle 6. Further, temperature sensors 8 and 9 are arranged on the bypass side of the bypass circuit 5 and on the suction side of the compressor 1, respectively. Reference numeral 10 is a heating heater control circuit for controlling on / off of the heating heater, and 11 is a saturation signal which sends a control signal to the heating heater control circuit 10 to calculate a saturated vapor temperature TS from a temperature T1 detected by the temperature sensor 8. It is a steam temperature calculation circuit. The TS calculated by the saturated steam temperature calculation circuit 11 and the temperature T2 detected by the temperature sensor 9 are sent to the valve opening calculation circuit 12, where the electric expansion valve 3 is operated as described in the section of the related art. Of the expansion valve drive circuit 1
The valve opening degree of the electric expansion valve 3 is controlled by 3.

Next, a method of calculating the saturated steam temperature in this saturated steam temperature detection circuit will be described. FIG. 2 shows this refrigeration cycle on the P-h (Mollier) diagram, and the points indicated by the symbols A and B in the figure show the state of the refrigerant at the positions A and B in FIG. Here, when the heater 7 is off, the refrigerant in the vicinity of the temperature sensor 8 is in the state of point C in FIG. When the heater 7 is turned on, the refrigerant is heated and the state of the refrigerant moves in the direction of the arrow a to the state of point D. Here, when the heater 7 is turned off again, the state of the refrigerant moves in the direction of arrow b and becomes the state of point C again. At this time, as is clear from the isotherm shown in FIG. 2, the speed of temperature decrease is large when moving in the heating area, and the speed of temperature decrease suddenly becomes gentle when entering the two-phase area. FIG. 3 shows the refrigerant temperature T1 detected by the temperature sensor 8.
Shows the change over time. TC and TD in the figure are C and D in FIG.
Is the refrigerant temperature in the state of point. As is clear from the figure, when the heater 7 is turned off, the refrigerant temperature sharply drops, but when it enters the two-phase region, the temperature drop suddenly becomes gentle. The temperature at time tsa at which this slope changes is the saturated steam temperature TS. Therefore, after the heater 7 is turned off, the refrigerant temperature T1 is detected by the temperature sensor 8 at predetermined intervals,
This can be detected by setting the temperature when the absolute value of the difference from the previously detected refrigerant temperature T1 is equal to or lower than a predetermined value as the saturated steam temperature.

Next, the specific control of the saturated vapor temperature detection circuit will be described. FIG. 4 is a flow chart of control in the saturated steam temperature calculation circuit 11. First, when the request for TS transmission is received from the valve opening calculation circuit 12 at predetermined intervals, the heater 7 is turned on. Then, when the temperature T1 detected by the temperature sensor 8 rises to TD shown in FIG. 2, the heater 7 is turned off to detect T1 at every predetermined cycle t1, and the difference (change amount) from the temperature Tm detected immediately before is detected. Absolute value | T1
When −Tm | becomes smaller than the predetermined value K, it is determined that the refrigerant temperature T1 at this time is the saturated vapor temperature TS, and TS = T1.
Then, the temperature signal of TS is sent to the valve opening calculation circuit 12.

As described above, even when the non-azeotropic mixed refrigerant is used as the refrigerant, the saturated vapor temperature of the refrigerant sucked into the compressor can be accurately detected without complicating the structure of the refrigeration cycle. It is possible to realize various refrigeration cycle control.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a refrigeration cycle diagram in the second embodiment of the present invention. The difference from the first embodiment is that the auxiliary throttle 6, the heater 7 and the heater control circuit 10 on the bypass circuit 5 are eliminated, and the valve opening degree can be controlled on the bypass circuit 5 by the expansion valve drive circuit 13. The expansion valve 14 is provided, and a heat exchange section 15 capable of exchanging heat with a pipeline connecting the compressor 1 and the condenser 2 is provided in a part of the pipeline on the downstream side.

A method of calculating the temperature saturated steam temperature in this saturated steam temperature detection circuit will be described. In this embodiment, since the refrigerant in the bypass circuit 5 is heated by the high temperature refrigerant gas discharged from the compressor 1, the heating amount cannot be controlled.
Therefore, the saturated steam temperature is calculated in the same manner as in the first embodiment by controlling the valve opening degree of the electric expansion valve 14 to control the circulation amount of the refrigerant flowing through the bypass circuit 5. That is, first, the valve opening degree of the electric expansion valve 14 is reduced to raise the refrigerant temperature T1 to TD in FIG. When T1 rises to TD, the valve opening degree of the electric expansion valve 14 is then increased by a predetermined amount every predetermined period, and the refrigerant temperature T1 is detected. Then,
As in the first embodiment, the temperature of the refrigerant drops sharply, but 2
When entering the phase range, the temperature drop suddenly slows down. The temperature at time tsa at which this slope changes is the saturated steam temperature TS.
Therefore, after the coolant temperature T1 reaches TD, the coolant temperature T1 is detected by the temperature sensor 8 in every predetermined cycle, and the temperature at the time when the absolute value of the difference from the coolant temperature T1 detected last time becomes equal to or less than the predetermined value is determined. It can be detected by setting the saturated vapor temperature.

Next, the specific control of the saturated vapor temperature detection circuit will be described. FIG. 6 is a flow chart of control in the saturated steam temperature calculation circuit 11. First, when a TS transmission request is received from the valve opening calculation circuit 12 at predetermined intervals, the expansion valve drive circuit 13 is sent to the expansion valve drive circuit 13 at predetermined intervals t2 until the temperature T1 detected by the temperature sensor 8 rises to TD shown in FIG. A signal is issued to reduce the valve opening degree of the electric expansion valve 14 by K2 pulses. Then, when the refrigerant temperature T1 rises to TD shown in FIG. 2, a signal is issued to the expansion valve drive circuit 13 at every predetermined cycle t3 to increase the valve opening degree of the electric expansion valve 14, and T1 is detected. When the absolute value | T1−Tm | of the difference (change amount) from the temperature Tm detected in step S1 becomes smaller than the predetermined value K, it is determined that the refrigerant temperature T1 at this time is the saturated vapor temperature TS, and TS = T1, The temperature signal of TS is sent to the valve opening calculation circuit 12.

As described above, even when the non-azeotropic mixed refrigerant is used as the refrigerant, the heat in the refrigeration cycle can be utilized, so that the saturated vapor temperature of the refrigerant sucked into the compressor can be increased without adding any heating means. Can be detected accurately,
This makes it possible to realize optimum refrigeration cycle control.

Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a refrigeration cycle diagram in the third embodiment of the present invention. The difference from the second embodiment is that an auxiliary evaporator 16 is provided to evaporate the refrigerant by passing a part of the pipeline on the downstream side of the electric expansion valve 14 on the bypass circuit 5 through the evaporator 4. is there.

The method of calculating the temperature saturated steam temperature in the saturated steam temperature detection circuit will be described. First, the valve opening of the electric expansion valve 14 is made small, and the refrigerant temperature T1 is shown in FIG.
Up to TD at. When T1 rises to TD, next, the valve opening degree of the electric expansion valve 14 is increased by a predetermined amount for each predetermined cycle, the refrigerant temperature T1 is detected, and then TS is obtained in the same manner as in the second embodiment. it can. The specific control is the same as the control flow chart of the second embodiment shown in FIG.

In the second embodiment, the bypass circuit 5
3 is heated by the high-temperature refrigerant gas discharged from the compressor 1, the TD shown in FIG. 3 is considerably high in temperature. It does not exceed the ambient temperature and is therefore stable at relatively low temperatures. Therefore, it takes a short time for the refrigerant temperature to reach TD from TS, and the saturated vapor temperature TS can be obtained in a short time.

As described above, even when the non-azeotropic mixed refrigerant is used as the refrigerant, the heat in the refrigeration cycle can be utilized, so that the saturated vapor temperature of the refrigerant sucked into the compressor can be controlled without adding a new heating means. It is possible to detect with high accuracy and in a short time, and thus it is possible to realize optimum refrigeration cycle control.

In the above first to third embodiments, the case where the saturated steam temperature detected by the saturated steam temperature detection circuit of the present invention is used for superheat control has been described, but the present invention is not limited thereto. , For example, the freezing of the evaporator is estimated from the detected saturated vapor temperature, a conversion formula to the saturated pressure is created, and the compressor suction pressure is calculated from the detected saturated vapor temperature and used for protection control. It can also be used for other controls.

In the first to third embodiments described above, one end of the bypass circuit 5 is connected to a part of the conduit connecting the condenser 2 and the pressure reducer (electric expansion valve 3), but this is not the only option. Instead, it is sufficient if the proportion of the liquid refrigerant is large and the pressure becomes higher than that on the suction side of the compressor 1. For example, when the decompressor is divided into two, it may be connected between the two decompressors, and when the decompressor is a capillary tube, it may be connected to any position on the pipeline of the capillary tube. Good.

Further, in the case of the heat pump cycle, even if the four-way valve is switched and the evaporator and the condenser are exchanged, one end of the bypass circuit should always be connected to the conduit from the condenser outlet to the pressure reducer outlet. If so, it is possible to configure the saturated vapor temperature detection circuit of the present invention. For example, if the pressure reducer is divided into two and one end of the bypass circuit is connected between the two pressure reducers, even if the condenser and the evaporator are exchanged, the intermediate pressure refrigerant can always flow to the bypass circuit. . Further, FIG. 8 shows an example of a refrigeration cycle diagram when the saturated vapor temperature detection circuit of the present invention is applied to a heat pump cycle. In the figure, 17 and 18 are check valves,
19 is a four-way valve. When such a refrigerant circuit is assembled, when the heat exchanger 2a is a condenser, the refrigerant flows as shown by a solid line, and when the heat exchanger 4a is a condenser, the refrigerant flows as shown by a broken line. Therefore, the high-pressure liquid refrigerant can always flow through the bypass circuit, and the saturated vapor temperature detection circuit of the present invention can be configured.

In the second and third embodiments described above, the auxiliary decompressor with variable decompression amount is described using the electric expansion valve, but the invention is not limited to this.
Other methods may be used as long as the amount of pressure reduction can be controlled.

Further, the saturated vapor temperature detection circuit of the present invention is
Not only the CFC-based refrigerant but also a non-azeotropic mixed refrigerant can be applied to other refrigerants.

[0036]

As is apparent from the above embodiment, the saturated vapor temperature detection circuit of the refrigeration cycle of the present invention has one end connected to the conduit from the condenser outlet to the pressure reducer outlet, and the other end from the evaporator outlet. A bypass circuit connected to the pipeline to the compressor inlet is provided, and an auxiliary decompressor, refrigerant heating means, and refrigerant temperature detection means are provided in this bypass circuit from the upstream side in order to control the heating amount of the refrigerant heating means. In the refrigerating cycle using the non-azeotropic mixed refrigerant, the refrigerating cycle using the non-azeotropic mixed refrigerant has a quantity controlling means and a judging means for judging the saturated vapor temperature from the amount of change by detecting the refrigerant temperature in a predetermined cycle by the refrigerant temperature detecting means. The saturated vapor temperature of the compressor suction refrigerant can be accurately detected without complicating the configuration, and thus optimal refrigeration cycle control can be realized.

Further, a bypass circuit having one end connected to a conduit from the condenser outlet to the decompressor outlet and the other end connected to a conduit from the evaporator outlet to the compressor inlet is provided. Auxiliary decompressor with variable decompression amount and refrigerant temperature detecting means are provided in order from the upstream side, and a part of a pipe line from the auxiliary decompressor outlet to the refrigerant temperature detecting means installation position and a pipe from the compressor outlet to the condenser inlet Heat exchange connection with part of the path,
By having a decompression amount control means for controlling the decompression amount of the auxiliary decompressor, a refrigerant temperature detecting means for detecting the refrigerant temperature in a predetermined cycle and having a judging means for judging the saturated vapor temperature from the change amount thereof, Since the heat can be utilized, the saturated vapor temperature of the compressor suction refrigerant can be accurately detected without newly adding a heating means, and thus optimal refrigeration cycle control can be realized.

Further, a bypass circuit having one end connected to a pipeline from the condenser outlet to the decompressor outlet and the other end connected to a pipeline from the evaporator outlet to the compressor inlet is provided. Auxiliary decompressor with variable decompression amount and refrigerant temperature detecting means are provided in order from the upstream side, and a part of the pipeline from the outlet of the auxiliary decompressor to the installation location of the refrigerant temperature detecting means is arranged in the evaporator, and the auxiliary decompressing By having a decompression amount control means for controlling the decompression amount of the container and a determination means for detecting the refrigerant temperature at a predetermined cycle by the refrigerant temperature detection means and determining the saturated vapor temperature from the amount of change, heat exchange with a high temperature heating source Since the refrigerant in the bypass circuit can be turned into superheated steam without doing so, it is possible to accurately detect the saturated vapor temperature of the compressor suction refrigerant in a short time, and thereby achieve optimal refrigeration cycle control. it can.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram in a first embodiment of a saturated vapor temperature detection circuit of the present invention.

FIG. 2 is a refrigeration cycle diagram on the Ph diagram in the example.

FIG. 3 is a characteristic diagram showing the change over time of the refrigerant temperature in the same example.

FIG. 4 is a flow chart of control in the embodiment.

FIG. 5 is a refrigeration cycle diagram in the second embodiment of the saturated vapor temperature detection circuit of the present invention.

FIG. 6 is a flow chart of control in the embodiment.

FIG. 7 is a refrigeration cycle diagram in a third embodiment of the saturated vapor temperature detection circuit of the present invention.

FIG. 8 is a refrigeration cycle diagram when the saturated vapor temperature detection circuit of the present invention is applied to a heat pump cycle.

FIG. 9 is a refrigeration cycle diagram of a conventional saturated vapor temperature detection circuit.

FIG. 10 is a refrigeration cycle diagram on the Ph diagram in the saturated vapor temperature detection circuit.

FIG. 11 is a relationship diagram between the superheat amount and the valve opening change amount of the electric expansion valve.

FIG. 12 is a refrigeration cycle diagram on the Ph diagram when a non-azeotropic mixed refrigerant is used in a conventional saturated vapor temperature detection circuit.

[Explanation of symbols]

 1 Compressor 2 Condenser 2a Heat exchanger 3 Electric expansion valve (pressure reducer) 4 Evaporator 4a Heat exchanger 5 Bypass circuit 6 Auxiliary throttle (auxiliary pressure reducer) 7 Heating heater (refrigerant heating means) 8 Temperature sensor (refrigerant temperature) Detection means) 10 Heating heater control circuit (heating amount control means) 11 Saturated steam temperature calculation circuit (determination means) 13 Expansion valve drive circuit (decompression amount control means) 14 Electric expansion valve (auxiliary decompressor with variable decompression amount) 15 Heat Exchange part 16 Auxiliary evaporator

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshinori Kobayashi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A non-azeotropic mixed refrigerant in which two or more kinds of refrigerants having different boiling points are mixed at a predetermined ratio is used as a refrigerant, and a compressor, a condenser, a pressure reducer, and an evaporator are sequentially connected in an annular shape by pipes. A refrigerant circuit is constructed by connecting one end to the pipeline from the condenser outlet to the decompressor outlet, and the other end is connected to the pipeline from the evaporator outlet to the compressor inlet. The circuit is provided with an auxiliary decompressor, a refrigerant heating means, and a refrigerant temperature detection means in order from the upstream side, and a heating amount control means for controlling the heating amount of the refrigerant heating means, and the refrigerant temperature detection means detects the refrigerant temperature in a predetermined cycle. A saturated steam temperature detection circuit for a refrigeration cycle, which has a determining means for determining the saturated steam temperature based on the amount of change in temperature. 2. A non-azeotropic mixed refrigerant in which two or more kinds of refrigerants having different boiling points are mixed at a predetermined ratio is used as a refrigerant, and a compressor, a condenser, a decompressor, and an evaporator are sequentially connected in an annular shape by pipes. A refrigerant circuit is constructed by connecting one end to the pipeline from the condenser outlet to the decompressor outlet, and the other end is connected to the pipeline from the evaporator outlet to the compressor inlet. Auxiliary decompressor with variable decompression amount in order from the upstream side to the circuit,
Refrigerant temperature detection means is provided, and a part of the pipeline from the auxiliary decompressor outlet to the refrigerant temperature detection means installation position and a portion of the pipeline from the compressor outlet to the condenser inlet are heat-exchanged. Of the refrigeration cycle having a pressure reducing amount control means connected to control the pressure reducing amount of the auxiliary pressure reducer, a means for detecting the refrigerant temperature by the refrigerant temperature detecting means in a predetermined cycle, and determining the saturated vapor temperature from the change amount thereof. Saturated steam temperature detection circuit. 3. A non-azeotropic mixed refrigerant in which two or more kinds of refrigerants having different boiling points are mixed at a predetermined ratio is used as a refrigerant, and a compressor, a condenser, a decompressor, and an evaporator are sequentially connected by a pipe in an annular shape. A refrigerant circuit is constructed by connecting one end to the pipeline from the condenser outlet to the decompressor outlet, and the other end is connected to the pipeline from the evaporator outlet to the compressor inlet. Auxiliary decompressor with variable decompression amount in order from the upstream side to the circuit,
A refrigerant temperature detecting means is provided, and a part of a pipe line from the outlet of the auxiliary pressure reducer to the installation position of the refrigerant temperature detecting means is provided in the evaporator, and a pressure reduction amount control for controlling the pressure reduction amount of the auxiliary pressure reducer is provided. A saturated vapor temperature detection circuit for a refrigeration cycle, comprising: a means for detecting the refrigerant temperature at a predetermined cycle by the refrigerant temperature detecting means;