JP3178178B2 - Refrigeration cycle saturated steam temperature detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, regulations on chlorofluorocarbons that destroy the ozone layer have been tightened from the standpoint of protecting the global environment. CFCs (chlorofluorocarbons), which have a large destructive power, have been completely abolished at the end of 1995. In addition, HCFCs (hydrochlorofluorocarbons), which have relatively small destructive power, have been regulated in total amount since 1996, and it has been decided that they will be totally abolished in the future. Therefore, for devices using chlorofluorocarbon as a refrigerant, alternative refrigerants are being developed, and HFCs (hydrofluorocarbons) that do not destroy the ozone layer are being studied. However, HCFCs used in refrigerators and air conditioners are being studied. There is no HFC that can be used alone as an alternative refrigerant to HFC. Therefore, a non-azeotropic mixed refrigerant obtained by mixing two or more HFC-based 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
Superheat control was performed to improve (coefficient of performance) and ensure the reliability of the compressor, and a saturation steam temperature detection circuit was provided for that purpose.

Hereinafter, a conventional saturated steam temperature detecting circuit will be described with reference to the drawings. FIG. 9 is a refrigeration cycle diagram of a conventional refrigerator, an air conditioner, and the like. In the figure, 1 is a compressor, 2 is a condenser, 3 is an electric expansion valve that can control the valve opening by using a stepping motor by pulse, 4
Are evaporators, which are sequentially connected in a ring shape.
A bypass circuit 5 has one end connected to a pipe connecting the condenser 2 and the electric expansion valve 3 and the other end connected to a pipe connecting the evaporator 4 and the compressor 1. Is provided with an auxiliary aperture 6. Further, temperature sensors 8 and 9 are disposed on the bypass circuit 5 and the suction-side pipe line of the compressor 1, respectively. The valve opening of the expansion valve 3 is calculated, a valve opening signal is sent out, and the valve opening of the electric expansion valve 3 is controlled by the expansion valve drive circuit 13 in response to the valve opening signal.

FIG. 10 shows this refrigeration cycle on a Ph (Mollier) diagram.
The points of the symbols B and C indicate the state of the refrigerant at the positions A, B and C in FIG. As is clear from the figure, since the gas is in a gas-liquid two-phase state at the point C, 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 indicates the superheat amount ΔT of the refrigerant drawn into the compressor 1.

Next, control of the 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. The valve opening degree is determined at predetermined intervals from the temperature signals TS and T2 detected by the temperature sensors 8 and 9. The arithmetic circuit 12 calculates the superheat amount ΔT, and FIG.
According to the relationship shown in FIG. 1 (if the superheat amount ΔT is larger than the set value, the valve opening is increased, and if it is smaller than the set value, the valve opening is decreased), the valve opening signal of the electric expansion valve 3 is expanded. Is sent to the valve drive circuit 13 and the expansion valve drive circuit 13
To control the valve opening of the electric expansion valve 3 to maintain the superheat amount ΔT at the set value.

[0007]

However, the above-mentioned conventional saturated steam temperature detecting circuit of the refrigeration cycle has the following problems.

FIG. 12 shows a refrigeration cycle in which a non-azeotropic mixed refrigerant is used as a refrigerant on a Ph (Mollier) diagram. In FIG. 10 shows the state of the refrigerant at positions A, B, and C in FIG. Here, the amount of superheat at point B is
It can be obtained from the difference between the temperature at point B and its saturated steam temperature (point E). Here, in the case of the single refrigerant, the temperature at the point C is the same as the saturated vapor temperature as shown in FIG. 10, but in the case of the non-azeotropic refrigerant mixture, as shown in FIG. Since the line is a downward-sloping line, the temperature at point C is lower than the temperature of 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 order to perform control to maintain the set value in this state, the refrigerant is: The actual superheat amount is sucked into the compressor in a state lower than the set value or in a state of wet steam.

For this reason, there is a possibility that the reliability of the compressor and the COP may be reduced due to the liquid compression.

In view of the above problems, a saturated vapor temperature detecting circuit for a refrigeration cycle according to the present invention has a saturation vapor temperature of refrigerant sucked into a compressor in a refrigeration cycle using a non-azeotropic mixed refrigerant without complicating the structure of the refrigeration cycle. The aim is to realize optimum refrigeration cycle control.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a circuit for detecting a saturated vapor temperature of a refrigeration cycle according to the present invention comprises a non-azeotropic mixture in which two or more refrigerants having different boiling points are mixed at a predetermined ratio. Using a refrigerant, a compressor, a condenser, a decompressor, and an evaporator are sequentially connected in a loop with a pipe 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 is connected. Is provided with a bypass circuit connected to a pipe line from an evaporator outlet to a compressor inlet, and an auxiliary decompressor, a refrigerant heating unit, and a refrigerant temperature detecting unit are provided in this bypass circuit in order from the upstream side to heat the refrigerant heating unit. It has a heating amount control means for controlling the amount, and a discriminating means for detecting the refrigerant temperature at a predetermined cycle by the refrigerant temperature detecting means and discriminating the saturated steam temperature from the change amount.

Further, another circuit for detecting a saturated vapor temperature of a refrigeration cycle according to the present invention uses a non-azeotropic mixed refrigerant in which two or more refrigerants having different boiling points are mixed at a predetermined ratio.
A compressor, a condenser, a decompressor, and an evaporator are connected in order in a ring 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 is connected to the evaporator outlet. A bypass circuit connected to a pipe line from the compressor to the compressor inlet is provided, and an auxiliary pressure reducer and a refrigerant temperature detecting means are provided in this bypass circuit in order from the upstream side, and the refrigerant temperature detecting means is provided from the auxiliary pressure reducer outlet. A depressurization amount control means for connecting a part of the line leading to the installation position and a part of the line leading from the compressor outlet to the condenser inlet in a heat-exchange manner, and controlling the depressurization amount of the auxiliary decompressor; The refrigerant temperature detecting means detects the refrigerant temperature at a predetermined cycle, and has a determining means for determining the saturated steam temperature from the amount of change.

Further, another saturated vapor temperature detecting circuit of the refrigeration cycle of the present invention uses a non-azeotropic mixed refrigerant in which two or more types of refrigerants having different boiling points are mixed at a predetermined ratio.
A compressor, a condenser, a decompressor, and an evaporator are connected in order in a ring 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 is connected to the evaporator outlet. A bypass circuit connected to a pipe line from the compressor to the compressor inlet is provided, and an auxiliary pressure reducer and a refrigerant temperature detecting means are provided in this bypass circuit in order from the upstream side, and the refrigerant temperature detecting means is provided from the auxiliary pressure reducer outlet. A part of the pipeline leading to the installation position is disposed in the evaporator, and the temperature of the refrigerant is detected at a predetermined cycle by a decompression amount control means for controlling the decompression amount of the auxiliary decompressor and a refrigerant temperature detection means, and the change is detected. It has a determining means for determining the saturated steam temperature from the amount.

[0014]

The present invention has the following functions by 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. An auxiliary decompressor, a refrigerant heating unit, and a refrigerant temperature detection unit are provided in order from the upstream side, and the amount of change is detected by detecting the refrigerant temperature at a predetermined cycle by the heating amount control unit for controlling the heating amount of the refrigerant heating unit and the refrigerant temperature detection unit. By having a discriminating means for discriminating the saturated vapor temperature more accurately, in a refrigeration cycle using a non-azeotropic refrigerant mixture, the saturated vapor temperature of the refrigerant sucked into the compressor can be accurately detected without complicating the configuration of the refrigeration cycle. Thus, optimal refrigeration cycle control can be realized.

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. An auxiliary decompressor with a variable decompression amount and a refrigerant temperature detecting means are provided in order from the upstream side, and a part of a pipeline from an auxiliary decompressor outlet to a refrigerant temperature detecting means installation position and a pipe from the compressor outlet to the condenser inlet. Heat exchange with a part of the road,
A pressure reduction amount control means for controlling the pressure reduction amount of the auxiliary pressure reducer, and a determination means for detecting the refrigerant temperature at a predetermined cycle by the refrigerant temperature detection means and determining the saturated steam temperature from the change amount, so that the temperature during the refrigeration cycle can be reduced. Since heat can be used, the saturated vapor temperature of the refrigerant drawn into the compressor can be accurately detected without newly adding a heating means, thereby realizing optimal refrigeration cycle control.

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. An auxiliary pressure reducer and a refrigerant temperature detecting means are provided in order from the upstream side, and a part of a pipeline from an auxiliary pressure reducer outlet to a refrigerant temperature detecting means installation position is provided in the evaporator, and the auxiliary pressure reducing means is provided. A pressure-reducing amount control means for controlling a pressure-reducing amount of the vessel, and a discriminating means for detecting a refrigerant temperature at a predetermined cycle by a refrigerant temperature detecting means and discriminating a saturated steam temperature from a change amount thereof, thereby allowing heat exchange with a high-temperature heating source. Since the refrigerant in the bypass circuit can be turned into superheated steam without the need, the saturated vapor temperature of the refrigerant drawn into the compressor can be accurately detected in a short time, thereby realizing optimal refrigeration cycle control. it can.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. Note that components having the same functions as those described in the section of the related art are denoted 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 FIG. 1, reference numeral 1 denotes a compressor, 2 denotes a condenser, 3 denotes an electric expansion valve, and 4 denotes an evaporator, which are sequentially connected in a ring shape, and use a non-azeotropic mixed refrigerant as a refrigerant. A bypass circuit 5 has one end connected to a pipe connecting the condenser 2 and the electric expansion valve 3 and the other end connected to a pipe connecting the evaporator 4 and the compressor 1. Is provided with an auxiliary aperture 6. Further, a heater 7 for heating the refrigerant is mounted downstream of the auxiliary throttle 6. Further, temperature sensors 8 and 9 are provided on the bypass circuit 5 and the pipeline on the suction side of the compressor 1, respectively. Reference numeral 10 denotes a heater control circuit for controlling ON / OFF of the heater. Reference numeral 11 denotes a saturation signal for sending a control signal to the heater control circuit 10 and calculating a saturated steam temperature TS from the temperature T1 detected by the temperature sensor 8. 3 is a steam temperature calculation circuit. The TS calculated by the saturated steam temperature calculating circuit 11 and the temperature T2 detected by the temperature sensor 9 are sent to the valve opening calculating circuit 12, and as described in the section of the prior art, the electric expansion valve 3 is used here. , And sends a valve opening signal, and receives the valve opening signal to receive the expansion valve driving circuit 1.
At 3, the valve opening of the electric expansion valve 3 is controlled.

Next, a method of calculating the saturated steam temperature in the saturated steam temperature detection circuit will be described. FIG. 2 shows this refrigeration cycle on a Ph (Mollier) diagram. In FIG. 2, points indicated by symbols A and B indicate the state of the refrigerant at positions A and B in FIG. Here, when the heater 7 is turned off, the refrigerant near the temperature sensor 8 is in a state of a 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 arrow a, and the state of point D is reached. Here, when the heater 7 is turned off again, the state of the refrigerant moves in the direction of arrow b, and returns to the state at point C. At this time, as is clear from the isotherm shown in FIG. 2, the speed of the temperature drop is large when moving in the heating zone, and the speed of the temperature drop becomes abruptly slow when entering the two-phase zone. FIG. 3 shows the refrigerant temperature T1 detected by the temperature sensor 8.
Of FIG. TC and TD in the same figure are C and D in FIG.
Is the refrigerant temperature in the state of the point. As is clear from the figure, when the heater 7 is turned off, the temperature of the refrigerant rapidly decreases, but when the temperature enters the two-phase region, the temperature decreases rapidly and gradually. The temperature at the time tsa at which this inclination changes is the saturated steam temperature TS. Therefore, the coolant temperature T1 is detected by the temperature sensor 8 at predetermined intervals after the heater 7 is turned off.
The temperature can be detected by setting the temperature when the absolute value of the difference from the refrigerant temperature T1 detected last time becomes equal to or less than a predetermined value as the saturated steam temperature.

Next, a specific control of the saturated steam temperature detecting circuit will be described. FIG. 4 is a flowchart of the control in the saturated steam temperature calculation circuit 11. First, upon receiving a request for TS transmission at predetermined intervals from the valve opening calculation circuit 12, 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, T1 is detected every predetermined period t1, and the difference (change amount) from the temperature Tm detected immediately before is detected. Absolute value | T1
−Tm | is 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
And sends the TS temperature signal to the valve opening calculation circuit 12.

As described above, even when a non-azeotropic mixed refrigerant is used as the refrigerant, the saturated vapor temperature of the refrigerant drawn into the compressor can be accurately detected without complicating the structure of the refrigeration cycle. A refrigeration cycle control can be realized.

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 can be controlled by the expansion valve drive circuit 13 on the bypass circuit 5. An expansion valve 14 is provided, and a part of a pipe downstream of the expansion valve 14 is provided with a heat exchange part 15 capable of exchanging heat with a pipe connecting the compressor 1 and the condenser 2.

A method for calculating the temperature saturated steam temperature in the saturated steam temperature detecting 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 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 of the electric expansion valve 14 is reduced, and the refrigerant temperature T1 is increased to TD in FIG. When T1 rises to TD, the valve opening of the electric expansion valve 14 is increased by a predetermined amount at predetermined intervals, and the refrigerant temperature T1 is detected. Then,
As in the first embodiment, the refrigerant temperature drops rapidly,
When entering the phase region, the temperature drop suddenly slows down. The temperature at the time tsa at which this inclination 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 at predetermined intervals, and the temperature when the absolute value of the difference from the previously detected coolant temperature T1 becomes equal to or less than the predetermined value is determined. It can be detected by setting the saturated vapor temperature.

Next, a specific control of the saturated steam temperature detecting circuit will be described. FIG. 6 is a flowchart of the control in the saturated steam temperature calculation circuit 11. First, when a request for TS transmission is received at predetermined intervals from the valve opening calculation circuit 12, the expansion valve drive circuit 13 is activated 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 narrow the valve opening 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 sent to the expansion valve drive circuit 13 every predetermined period t3 to increase the valve opening of the electric expansion valve 14 and detect T1. When the absolute value | T1-Tm | of the difference (change amount) from the detected temperature Tm becomes smaller than the predetermined value K, it is determined that the refrigerant temperature T1 at this time is the saturated steam temperature TS, and TS = T1. The temperature signal of the TS is sent to the valve opening calculation circuit 12.

As described above, even when a non-azeotropic refrigerant mixture is used as the refrigerant, the heat in the refrigeration cycle can be used, so that the saturated vapor temperature of the refrigerant drawn into the compressor can be reduced without adding a new heating means. Can be detected with high accuracy,
This makes it possible to achieve optimal 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 for evaporating the refrigerant by passing a part of the pipeline on the bypass circuit 5 downstream of the electric expansion valve 14 through the evaporator 4 is provided. is there.

The method of calculating the temperature of the saturated steam temperature in the saturated steam temperature detection circuit will be described. First, the opening degree of the electric expansion valve 14 is reduced, and the refrigerant temperature T1 is reduced as shown in FIG.
To the TD at When T1 rises to TD, the valve opening of the electric expansion valve 14 is increased by a predetermined amount at predetermined intervals, the refrigerant temperature T1 is detected, and the TS is calculated in the same manner as in the second embodiment. it can. The specific control is the same as the control flowchart 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 becomes considerably high. It does not rise above ambient temperature and is therefore stable at relatively low temperatures. Therefore, the time required for the refrigerant temperature to reach TS from TD is short, and the saturated steam temperature TS can be obtained in a short time.

As described above, even when a non-azeotropic mixed refrigerant is used as the refrigerant, the heat in the refrigeration cycle can be used, and the saturated vapor temperature of the refrigerant drawn into the compressor can be reduced without adding a new heating means. Detection can be performed accurately and in a short time, thereby realizing optimal refrigeration cycle control.

In the first to third embodiments, the case where the saturated steam temperature detected by the saturated steam temperature detecting circuit of the present invention is used for superheat control has been described. However, the present invention is not limited to this. For example, estimating the freezing of the evaporator from the detected saturated steam temperature, creating a conversion formula to the saturated pressure, calculating the compressor suction pressure from the detected saturated steam temperature and using it for protection control, etc. It can be used for other controls.

In the first to third embodiments, one end of the bypass circuit 5 is connected to the outlet of the condenser 2 through the pressure reducing device.
Not to have been connected to a part of the conduit leading to the inlet of the (electric expansion valve 3) is not limited to this, by connecting at the higher pressure than the proportion most suction side of the compressor 1 of the liquid refrigerant
For example, the function of the bypass circuit 5 can be provided. For example, if the pressure reducer is divided into two, the bypass circuit 5
May be connected to a part of the conduit between the two decompressors, and if the decompressor is a capillary tube, connected to any position on the conduit from the inlet to the outlet of the capillary tube. You may. That is, the bypass circuit
Connect one end to the conduit from the condenser outlet to the pressure reducer outlet
With this, it is possible to have the function of the bypass circuit of the present invention.
it can.

In the case of the heat pump cycle, one end of the bypass circuit is always connected to the conduit from the outlet of the condenser to the outlet of the pressure reducer, even if the four-way valve is switched to switch the evaporator and the condenser. If so, it is possible to configure the saturated steam 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 through the bypass circuit. . FIG. 8 shows an example of a refrigeration cycle diagram when the saturated steam temperature detection circuit of the present invention is applied to a heat pump cycle. In the figure, reference numerals 17 and 18 denote check valves,
19 is a four-way valve. With such a refrigerant circuit, when the heat exchanger 2a is a condenser, the refrigerant flows as a solid line, and when the heat exchanger 4a is a condenser, the refrigerant flows as a broken line. Therefore, 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.

Further, in the second and third embodiments, the auxiliary pressure reducer having a variable pressure reduction amount has been described using the electric expansion valve. However, the present invention is not limited to this.
Other types may be used as long as the amount of reduced pressure can be controlled.

Further, the saturated steam temperature detecting circuit of the present invention comprises:
The present invention is not limited to a chlorofluorocarbon-based refrigerant, and can be applied to other refrigerants as long as they are non-azeotropic mixed refrigerants.

[0036]

As is clear from the above embodiment, the circuit for detecting the saturated steam temperature of the refrigeration cycle of the present invention has one end connected to the pipe from the condenser outlet to the pressure reducer outlet, and the other end connected to the evaporator outlet. A bypass circuit connected to a pipeline leading to the compressor inlet is provided, and an auxiliary pressure reducer, a refrigerant heating unit, and a refrigerant temperature detection unit are provided in this bypass circuit in order from the upstream side, and heating for controlling a heating amount of the refrigerant heating unit is provided. In the refrigerating cycle using the non-azeotropic mixed refrigerant, the amount controlling means, the refrigerant temperature detecting means having a judging means for detecting the refrigerant temperature at a predetermined cycle and judging the saturated vapor temperature from the change amount thereof, The saturated vapor temperature of the refrigerant drawn into the compressor can be accurately detected without complicating the configuration, thereby realizing optimal refrigeration cycle control.

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. An auxiliary decompressor with a variable decompression amount and a refrigerant temperature detecting means are provided in order from the upstream side, and a part of a pipeline from an auxiliary decompressor outlet to a refrigerant temperature detecting means installation position and a pipe from the compressor outlet to the condenser inlet. Heat exchange with a part of the road,
A pressure reduction amount control means for controlling the pressure reduction amount of the auxiliary pressure reducer, and a determination means for detecting the refrigerant temperature at a predetermined cycle by the refrigerant temperature detection means and determining the saturated steam temperature from the change amount, so that the temperature during the refrigeration cycle can be reduced. Since heat can be used, the saturated vapor temperature of the refrigerant drawn into the compressor can be accurately detected without newly adding a heating means, thereby realizing optimal refrigeration cycle control.

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. An auxiliary pressure reducer and a refrigerant temperature detecting means are provided in order from the upstream side, and a part of a pipeline from an auxiliary pressure reducer outlet to a refrigerant temperature detecting means installation position is provided in the evaporator, and the auxiliary pressure reducing means is provided. A pressure-reducing amount control means for controlling a pressure-reducing amount of the vessel, and a discriminating means for detecting a refrigerant temperature at a predetermined cycle by a refrigerant temperature detecting means and discriminating a saturated steam temperature from a change amount thereof, thereby allowing heat exchange with a high-temperature heating source. Since the refrigerant in the bypass circuit can be turned into superheated steam without the need, the saturated vapor temperature of the refrigerant drawn into the compressor can be accurately detected in a short time, thereby realizing optimal refrigeration cycle control. it can.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle diagram of a first embodiment of a saturated steam temperature detection circuit according to the present invention.

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

FIG. 3 is a characteristic diagram showing a temporal change of a refrigerant temperature in the embodiment.

FIG. 4 is a flowchart of control in the embodiment.

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

FIG. 6 is a flowchart of control in the embodiment.

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

FIG. 8 is a refrigeration cycle diagram when the saturated steam 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 steam temperature detection circuit.

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

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

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

[Explanation of symbols]

 Reference Signs List 1 compressor 2 condenser 2a heat exchanger 3 electric expansion valve (decompressor) 4 evaporator 4a heat exchanger 5 bypass circuit 6 auxiliary throttle (auxiliary decompressor) 7 heater (refrigerant heating means) 8 temperature sensor (refrigerant temperature) (Detection means) 10 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 section 16 auxiliary evaporator

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshinori Kobayashi 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-6-101911 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F25B 1/00

Claims (3)

(57) [Claims] 1. A non-azeotropic mixed refrigerant in which two or more refrigerants having different boiling points are mixed at a predetermined ratio as a refrigerant, and a compressor, a condenser, a decompressor, and an evaporator are sequentially connected in a ring by piping. 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. An auxiliary decompressor, a refrigerant heating unit, and a refrigerant temperature detection unit are provided in order from the upstream side in the circuit, and a heating amount control unit that controls a heating amount of the refrigerant heating unit, and a refrigerant temperature is detected at a predetermined cycle by the refrigerant temperature detection unit. And a saturated steam temperature detecting circuit of the refrigeration cycle having a judging means for judging the saturated steam temperature from the change amount. 2. A non-azeotropic mixed refrigerant in which two or more refrigerants having different boiling points are mixed at a predetermined ratio as a refrigerant, and a compressor, a condenser, a decompressor, and an evaporator are sequentially connected in a ring by piping. 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. Auxiliary pressure reducer with variable pressure reduction in order from the upstream to the circuit,
A refrigerant temperature detecting means is provided, and a part of a conduit from the auxiliary decompressor outlet to the refrigerant temperature detecting means installation position and a part of a conduit from the compressor outlet to the condenser inlet are heat-exchanged. A refrigeration cycle having a pressure reduction amount control means for controlling a pressure reduction amount of the auxiliary pressure reducer, a determination means for detecting a refrigerant temperature at a predetermined cycle by the refrigerant temperature detection means and determining a saturated steam temperature from a change amount thereof. Saturated steam temperature detection circuit. 3. A non-azeotropic mixed refrigerant in which two or more refrigerants having different boiling points are mixed at a predetermined ratio as a refrigerant, and a compressor, a condenser, a decompressor, and an evaporator are sequentially connected in a ring by piping. 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. Auxiliary pressure reducer with variable pressure reduction in order from the upstream to the circuit,
A pressure reducing amount control for providing a refrigerant temperature detecting means, arranging a part of a pipeline from an outlet of the auxiliary decompressor to a position where the refrigerant temperature detecting means is installed in the evaporator, and controlling a depressurizing amount of the auxiliary decompressor. A saturated steam temperature detection circuit for a refrigeration cycle, comprising: means for detecting a refrigerant temperature at a predetermined cycle by means of refrigerant temperature detecting means, and judging saturated steam temperature from an amount of change.