JP2983853B2 - Vapor compression refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor compression refrigerator in which a mixed refrigerant in which a plurality of types of refrigerants are mixed is enclosed, and more particularly to detection of a change in the mixing ratio of the mixed refrigerant and control of the flow rate of the refrigerant.

[0002]

2. Description of the Related Art Conventionally, in a vapor compression refrigerator used for indoor air conditioning, the indoor temperature is controlled to a set temperature. In addition, in order to maximize the cooling capacity of the refrigerator itself and maintain a stable refrigerant state inside the refrigerator,
The control of the refrigerant flow rate is performed.

For example, in the case of cooling, heat inside a room is absorbed by a refrigerant by an evaporator, and heat absorbed by the refrigerant is released outside the room by a condenser, thereby performing heat exchange between the inside and the outside of the room. When the room temperature is higher than the set temperature, the compressor is operated, and when the room temperature is lower than the set temperature, the operation of the compressor is stopped.

[0004] The control of the flow rate of refrigerant in a refrigerator is performed by controlling the degree of opening and closing of an electronic expansion valve provided between an evaporator and a condenser. This type of control includes control called superheat control. In the superheat control, the superheat at the evaporator outlet converges to the control target value,
The degree of opening and closing of the electronic expansion valve is controlled.

FIG. 7 shows a refrigerant circuit of a conventional vapor compression refrigerator in which superheat control is performed.

[0006] The vapor compression refrigerator includes an outdoor unit 5 and an indoor unit 6. The outdoor unit 5 includes a compressor 3 and a four-way valve 9.
And an outdoor heat exchanger 2. The indoor unit 6 is provided with the electronic expansion valve 4 and the indoor heat exchanger 1. These devices are connected by a refrigerant pipe 7.

The electronic expansion valve 4 is electrically driven by, for example, a stepping motor and its opening / closing degree can be adjusted. The four-way valve 9 switches the connection of the compressor 3 connected between the indoor heat exchanger 1 and the outdoor heat exchanger 2 via the refrigerant pipe 7 according to the operation state. During the cooling operation, the four-way valve 9 is switched so that the refrigerant flows from the indoor heat exchanger 1 to the four-way valve 9, the compressor 3, the four-way valve 9, and the outdoor heat exchanger 2 in this order. During the heating operation, the four-way valve 9 is switched so that the refrigerant flows from the outdoor heat exchanger 2 to the four-way valve 9, the compressor 3, the four-way valve 9, and the indoor heat exchanger 1 in this order. FIG. 7 shows a case of the cooling operation, in which the refrigerant flows in the pipe 7 in the direction of the arrow shown in the drawing.

During the cooling operation, the indoor heat exchanger 1 operates as an evaporator, and the outdoor heat exchanger 2 operates as a condenser, and vice versa during the heating operation. A first temperature detecting means 10 composed of a thermistor is provided at an appropriate position in the piping inside the indoor heat exchanger 1 from the refrigerant inflow side to the intermediate position during the cooling operation. On the refrigerant discharge side of the indoor heat exchanger 1 during the cooling operation, a second temperature detecting means 11 made of a thermistor is provided.

[0009] In an appropriate position from the refrigerant inflow side to the intermediate position in the piping inside the outdoor heat exchanger 2 during the heating operation,
Third temperature detecting means 12 composed of a thermistor is provided. Further, a fourth temperature detecting means 13 including a thermistor is provided on the refrigerant discharge side of the outdoor heat exchanger 2 during the heating operation.

During the cooling operation, the degree of superheat of the refrigerant at the outlet of the indoor heat exchanger 1 operating as an evaporator is calculated based on the temperatures detected by the first and second temperature detecting means 10 and 11. The degree of superheat generally refers to a temperature rise from the saturated vapor temperature of the refrigerant. In the conventional refrigerator, since the refrigerant temperature on the refrigerant inflow side of the evaporator during the normal operation is a value that is substantially lower than the saturated vapor temperature, the temperature of the detected temperature of the first and second temperature detecting means 10, 11 The degree of superheat at the evaporator outlet is calculated based on the difference. Similarly, during the heating operation, the degree of superheat of the refrigerant at the outlet of the outdoor heat exchanger 2 operating as an evaporator is calculated based on the temperatures detected by the third and fourth temperature detecting means 12 and 13.

FIG. 8 shows an ideal change in the refrigerant temperature inside the evaporator when a single refrigerant is sealed in the refrigerator as the refrigerant. In FIG. 8, the horizontal axis indicates the distance from the refrigerant inlet of the refrigerant pipe disposed inside the evaporator, and the vertical axis indicates the temperature of the refrigerant located at that distance.

As can be seen from FIG. 8, the refrigerant temperature gradually rises as the refrigerant moves away from the refrigerant inlet (a region) due to the heat deprived of the heat from the outside air, and has passed through a state where the refrigerant temperature does not change (b region). Thereafter, the refrigerant temperature rises again to the refrigerant discharge port of the evaporator (region c).

That is, in the region a, the temperature of the refrigerant rises in the liquid state, and when the temperature of the refrigerant reaches the saturated vapor temperature under the pressure, the temperature does not rise as shown in the region b, and the refrigerant changes from the liquid to the gas. Is evaporated, and the refrigerant becomes a gas-liquid two-phase state in which a refrigerant in a gaseous state and a refrigerant in a liquid state are mixed.
Then, when all the refrigerants are in a gaseous state, the refrigerant temperature rises again as shown in a region c. When the refrigerant temperature at the evaporator outlet is higher than the saturated vapor temperature, that is, when the refrigerant is completely in a gaseous state at the evaporator outlet, it is generally called an overheated state. The degree of superheat in FIG. 8 is shown as x.

In the superheat degree control, the superheat degree at the evaporator outlet is set to a control target value for maximizing the refrigeration capacity owned by the refrigerator itself and keeping the refrigerant state inside the refrigerator most stable. The degree of opening and closing of the electronic expansion valve 4 is controlled so as to converge. By performing such superheat degree control, it is possible to perform highly accurate refrigerant flow rate control in a refrigeration cycle using a single refrigerant.

[0015]

In recent years, stratospheric ozone depletion due to chlorofluorocarbons has become a global environmental problem, and fluorocarbons (hereinafter referred to as “specified fluorocarbons”), which have a large stratospheric ozone depletion potential, have already been developed. Use and production are regulated by international treaties, and there is a movement to abolish the use and production of CFCs in the future.

A chlorodifluoroethane (R2) widely used in a conventional vapor compression refrigerator is used.
As for 2), although it is not a specific CFC, it is capable of destructing the stratospheric ozone layer, so there is a movement to abolish its use and production in the future, as with the specific CFC.

Therefore, recently, alternative refrigerants having a refrigerating capacity similar to that of R22 have been actively studied, and among them, two or three non-azeotropic mixed refrigerants have been proposed as promising refrigerants. .

However, when a mixed refrigerant is used as the refrigerant, the mixing ratio of the mixed refrigerant sealed in the refrigerator changes due to refrigerant leakage due to aging or the like. When the mixing ratio of the mixed refrigerant changes, there is a problem that it is difficult to perform stable refrigerant flow control with the initially set control parameter values. In addition, when the change in the mixture ratio is large, the performance of the refrigerator cannot be sufficiently exhibited, so that it is necessary to refill the refrigerant. Here, the control parameters are, for example, when the refrigerant flow rate control is performed by PID control, a proportional gain, an integration time (reset time), and a differentiation time (rate time).
Point to.

An object of the present invention is to provide a vapor compression refrigerator capable of detecting a change in a mixing ratio due to refrigerant leakage, performing optimal refrigerant flow control, and suppressing a decrease in refrigerator performance.

Further, according to the present invention, when the mixture ratio of the mixed refrigerant greatly changes from the initial mixture ratio due to refrigerant leakage, refilling of the refrigerant can be promoted, and refilling of the refrigerant can be performed accurately and efficiently. It is an object of the present invention to provide a vapor compression refrigerator that can perform well.

[0021]

According to a first aspect of the present invention, there is provided a vapor-compression refrigerator comprising a mixed refrigerant containing two or more refrigerants in a refrigeration cycle including a compressor, a condenser, an expansion valve, and an evaporator. In the vapor compression refrigerator in which is enclosed, based on the data including the amount of change of the detected refrigerant temperature near the refrigerant discharge side of the evaporator with respect to the operation amount of the expansion valve every fixed time,
It is characterized by comprising calculation means for calculating the mixture ratio of the mixed refrigerant, and control means for controlling the degree of opening and closing of the expansion valve based on the mixture ratio of the mixed refrigerant calculated by the calculation means.

A second vapor compression refrigerator according to the present invention is a vapor compression compressor in which a mixed refrigerant containing two or more types of refrigerant is sealed in a refrigeration cycle including a compressor, a condenser, an expansion valve, and an evaporator. Calculating means for calculating a mixing ratio of a mixed refrigerant based on data including an amount of change in a detected refrigerant temperature near a refrigerant discharge side of an evaporator with respect to an operation amount of an expansion valve every fixed time in a refrigerator. Control means for controlling the degree of opening and closing of the expansion valve based on the mixture ratio of the mixed refrigerant calculated by the above, and the mixing ratio of the mixed refrigerant calculated by the calculating means changes by a predetermined amount or more with respect to the initial mixing ratio. In this case, the mixing ratio of the mixed refrigerant is largely changed as compared with the initial mixing ratio, and a means for informing the mixing ratio of the mixed refrigerant calculated by the calculating means is provided.

[0023]

The main part of the calculating means is constituted by, for example, a neural network.

[0025]

In the first vapor compression refrigerator according to the present invention,
The mixing ratio of the mixed refrigerant is calculated based on the data including the amount of change in the detected refrigerant temperature near the refrigerant discharge side of the evaporator with respect to the operation amount of the expansion valve every fixed time. Then, the degree of opening and closing of the expansion valve is controlled based on the calculated mixture ratio of the mixed refrigerant.

In the second vapor compression refrigerator according to the present invention, based on the data including the amount of change in the detected refrigerant temperature near the refrigerant discharge side of the evaporator with respect to the amount of operation of the expansion valve at regular intervals, the mixed refrigerant Is calculated. Then, the degree of opening and closing of the expansion valve is controlled based on the calculated mixture ratio of the mixed refrigerant.

When the mixture ratio of the mixed refrigerant calculated by the calculation means has changed by a predetermined value or more with respect to the initial mixture ratio, the mixture ratio of the mixed refrigerant greatly changes as compared with the initial mixture ratio. And the mixture ratio of the mixed refrigerant calculated by the calculation means.

By being notified that the mixing ratio of the mixed refrigerant has greatly changed as compared with the initial mixing ratio, it is notified that the service engineer needs to refill the refrigerant. Then, from the notified information of the mixing ratio of the refrigerant, the reduced refrigerant among the refrigerants included in the mixed refrigerant is found.
Therefore, when refilling the refrigerant, the reduced refrigerant can be replenished, so that the refrigerant can be recharged accurately and efficiently.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a refrigerant circuit of a vapor compression refrigerator. 1, the same components as those in FIG. 7 are denoted by the same reference numerals, and the description thereof will be omitted. As a vapor compression refrigerator in this embodiment, like an inverter air conditioner,
A compressor in which the drive frequency of the compressor changes is used.
The basic operation principle of the refrigeration cycle is the same as that of the conventional example described above.

In this vapor compression refrigerator, the indoor unit 6 is provided with an indoor blower 14 that draws in indoor air and sends it to the indoor heat exchanger 1. Further, an indoor suction temperature detecting means 16 for detecting the temperature of the suction air from the indoor blower 14 is provided.

The outdoor unit 5 is provided with an outdoor blower 15 that draws in outside air and sends it to the outdoor heat exchanger 2. Also,
An outdoor suction temperature detecting means 17 for detecting a suction air temperature of the outdoor blower 15 is provided.

FIG. 2 shows a change in refrigerant temperature inside the evaporator when a mixed refrigerant obtained by mixing two or more refrigerant components having different boiling points is used as the refrigerant.

When a non-azeotropic mixed refrigerant is used as the refrigerant, since the saturated vapor temperatures of the individual refrigerants at the same pressure in the evaporator are different, a gas-liquid mixture having a constant temperature like the single refrigerant described above is used. There is no two-phase portion (region b in FIG. 8). Therefore, there is a refrigerant state in which only some types of refrigerant are completely evaporated before all the individual refrigerants evaporate to the overheated state (region c in FIG. 8).

Therefore, when a mixed refrigerant is used,
As shown in FIG. 2, in the gas-liquid two-phase state, the temperature does not become constant as in the case of a single refrigerant, but rises (b ′ region in FIG. 2). The area a ′ in FIG. 2 corresponds to the area a in FIG. 8, and the area c ′ in FIG. 2 corresponds to the area c in FIG. FIG. 2 shows the degree of superheat in the case of using the mixed refrigerant by y.

There is a large difference between the degree of temperature rise in the gas-liquid two-phase state and the degree of temperature rise in the superheated state with respect to a fixed amount of operation of the electronic expansion valve 4, and when transitioning from the gas-liquid two-phase state to the overheated state. In addition, the degree of temperature rise of the refrigerant temperature with respect to the constant operation amount of the electronic expansion valve 4 increases. The state change point in this case is shown as point A in FIG.

When the mixing ratio of the charged refrigerant changes with time, the degree of temperature rise of the refrigerant temperature with respect to a constant operation amount of the electronic expansion valve 4 in each of the gas-liquid two-phase state and the superheated state changes.

In this embodiment, a change in the mixing ratio of the charged refrigerant is detected based on the characteristics of the refrigerant in the evaporator using two or more types of non-azeotropic mixed refrigerants. Hereinafter, the detection of the mixing ratio of the charged refrigerant and the control of the flow rate of the refrigerant will be described in detail.

FIG. 3 is a schematic block diagram of a vapor compression refrigerator of the present invention.

The vapor compression refrigerator includes a control unit 101 for controlling various input / output devices.

The timing signal is sent from the timing signal generator 102 to the controller 101 at predetermined time intervals (every 30 seconds in this embodiment). The temperature data storage unit 103 stores the second temperature detection unit 11 or the fourth temperature detection unit 13.
Is input, and the refrigerant temperature T1 30 seconds before and the current refrigerant temperature T2 are stored.

The transition temperature calculating means 104 calculates the change amount t (= (T2−T1)) of the refrigerant temperature obtained from the refrigerant temperature stored in the temperature data storage section 103 and the operation amount of the electronic expansion valve 4 during that time. Based on the ratio t / v to v, the temperature (corresponding to the temperature at point A in FIG. 2) at which the superheated state (a state in which all of the refrigerant is evaporated) at the evaporator outlet is calculated.

More specifically, the transition temperature calculating means 104 determines whether or not the current t / v value has increased by more than a predetermined threshold value from the previous t / v value, so that the transition to the superheated state at the evaporator outlet is performed. Is calculated.

The superheat degree calculating means 105 calculates the evaporator temperature based on the evaporator outlet temperature detected by the second temperature detecting means 11 or the fourth temperature detecting means 13 and the transition temperature calculated by the transition temperature calculating means 104. The degree of superheat at the outlet (corresponding to y in FIG. 2) is calculated.

The operating state storage unit 106 stores the indoor suction temperature detecting means 16 or the outdoor suction temperature detecting means 17.
Temperature of the evaporator, the set airflow of the evaporator set in the indoor blower 14 or the outdoor blower 15, the degree of opening and closing of the electronic expansion valve 4, and whether the evaporator outlet is overheated. Data indicating whether or not the driving frequency of the compressor 3 is stored is stored.

The mixing ratio calculating means 107 is based on various operating state data stored in the operating state storage section 106 and the t / v value calculated by the transition temperature calculating means 104.
Mixing ratio of mixed refrigerant and refrigerant circulation amount (total amount of mixed refrigerant)
Is calculated. In addition to the t / v value, the operating state storage unit 106
The reason why the mixing ratio of the mixed refrigerant is calculated in consideration of the various operating state data stored in the storage unit is that the t / v value changes depending on the value of the various operating state data even if the mixing ratio is the same. is there.

The mixture ratio storage unit 108 stores the mixture ratio (initial mixture ratio) of the refrigerant mixture initially sealed in the refrigerator, and the current mixture ratio of the refrigerant mixture calculated by the mixture ratio calculation means 107. The (calculated mixture ratio) and the refrigerant circulation amount are stored. Note that, at the initial stage, the mixing ratio of the initially enclosed mixed refrigerant is stored as the calculated mixing ratio.

The notifying means 109 includes the mixing ratio calculating means 107
If the mixture ratio calculated by the above changes significantly from the initial mixture ratio and maintenance and inspection work by a serviceman is required,
The serviceman call lamp provided in the operation display unit 111 is turned on, and the display unit provided in the operation display unit 111 displays the current mixing ratio of the mixed refrigerant and the refrigerant circulation amount.

Thus, the use of the refrigerator in a state where the performance of the refrigerator cannot be sufficiently exhibited can be stopped, and the service person can refill each refrigerant. In addition, since the current mixture ratio and the refrigerant circulation amount are displayed on the display, it is possible to grasp the decrease amount of the reduced refrigerant among the refrigerants included in the mixed refrigerant. Therefore, by filling the reduced refrigerant by the reduced amount, the mixing ratio of the mixed refrigerant can be set to the initial mixing ratio.

The ROM 110 stores a program for the control unit 101 and the like. Therefore, the control unit 101
Controls each device such as the electronic expansion valve 4 based on this program.

The degree of opening and closing of the electronic expansion valve 4 is adjusted by a control pulse sent from the control unit 101. In this embodiment, the opening / closing degree in the fully closed state is “0”, the opening / closing degree in the fully open state is “500”, and the opening degree during that period is controlled by a value divided into 500 steps. The initial value is set to “100”.

The control unit 101 determines whether the operation is the cooling operation or the heating operation. Based on the input signal from the timing signal generation unit 102, the control unit 101 detects the refrigerant temperature detected by the second temperature detecting means 11 during the cooling operation. Is taken as the evaporator outlet temperature and stored in the temperature data storage section 103. During the heating operation, the refrigerant temperature detected by the fourth temperature detecting means 13 is taken as the evaporator outlet temperature and stored in the temperature data storage section 103.

Further, the control unit 101 fetches, based on the input signal from the timing signal generating unit 102, the temperature of the intake air and the set amount of air blown from the indoor heat exchanger 1 which operates as an evaporator during the cooling operation, and stores the operation state. Part 106
During the heating operation, the intake air temperature of the outdoor heat exchanger 2 operating as an evaporator 2 and the set airflow are taken in and stored in the operation state storage unit 106.

In the ROM 110, control parameter values used while the compressor is in a non-superheated state when the compressor is started and control parameter values used after the compressor is overheated are separately stored. Each parameter value includes an initial control parameter value for the initial mixture ratio and a control parameter value for each mixture ratio when the mixture ratio changes. ROM
Each control parameter value stored in 110 is an appropriate control parameter value obtained in advance by an experiment. The control unit 101 determines, from the control parameter values stored in the ROM 110, whether or not the compressor is in the non-superheated state at the time of starting the compressor or after the superheated state, and the control parameter according to the mixture ratio of the mixed refrigerant. The value is read and used as a control parameter value for refrigerant flow rate control.

As a result, the conventional problem, that is, before the compressor is overheated at the time of starting the compressor,
If the same control parameter value is used, it is possible to solve the problem that hunting occurs in the control result, and it is not possible to quickly stabilize the desired degree of superheat. Further, even if the mixture ratio of the mixed refrigerant changes due to refrigerant leakage, an appropriate control parameter value corresponding to the mixture ratio is reset, so that stable refrigerant flow control can be performed, and the performance of the refrigerator decreases. Can be suppressed.

FIG. 4 shows the structure of the main part of the mixture ratio calculating means 107.

The main part of the mixture ratio calculating means 107 is constituted by a multilayer neural network 41 of a neurocomputer. The neural network 41 includes an input layer 42, an intermediate layer 43, and an output layer 44.

The input layer 42 includes six input units I1 to I1.
I6. The intake air temperature stored in the operation state storage unit 106 is input to the input unit I1. The input unit I2 includes an operation state storage unit 1
The expansion valve opening stored in 06 is input. The air volume stored in the operation state storage unit 106 is input to the input unit I3. To the input unit I4, data (whether or not there is an overheating state) stored in the operating state storage unit 106 indicating whether or not the apparatus is in an overheating state is input. Input unit I5
Has the value of t /
The v value is entered. The drive frequency of the compressor 3 stored in the operation state storage unit 106 is input to the input unit I6.

The intermediate layer 43 is composed of each unit I of the input layer 42.
15 intermediate units M1 interconnected with 1 to I6
To M15.

The output layer 44 is composed of each unit M of the intermediate layer 43.
3 mutually connected to M15 and enclosed in a refrigerator
It is composed of three output units O1 to O3 each of which outputs a mixing ratio of a mixed refrigerant composed of various kinds of refrigerants, and an output unit O4 which outputs a refrigerant circulation amount.

In this embodiment, the case where three kinds of non-azeotropic mixed refrigerants are used as a mixed refrigerant has been described.
It is not necessary to be specified as a mixed refrigerant composed of different types of refrigerants. In addition, although the number of units in the intermediate layer is set to 15, it does not need to be particularly specified to this number. Further, there may be a plurality of intermediate layers.

The learning of the neural network 41 is performed as follows. First, through experiments in advance, for each of a large number of combinations of the mixing ratio of the mixed refrigerant and the refrigerant circulation amount, a representative value of the suction air temperature, the expansion valve opening degree, the air flow rate, the presence or absence of an overheat state, and the driving frequency of the compressor 3 is shown. Find the t / v value for the combination. And, intake air temperature, expansion valve opening, air flow, presence or absence of overheating,
The neural network 41 is learned by the back propagation method using the drive frequency and t / v value of the compressor 3 as input patterns, and the combination of the mixture ratio of the mixed refrigerant and the refrigerant circulation amount for each input pattern as teacher data.

In the neural network 41 after learning,
Various operation state data stored in the operation state storage unit 106 and t calculated by the transition temperature calculation unit 104
By inputting the / v value, the mixing ratio of the mixed refrigerant and the refrigerant circulation amount can be obtained.

By the way, in the case of a mixed refrigerant composed of three or more types of refrigerants, t /
A certain combination pattern of the v value and the various operation state data may correspond to each other. That is, two different mixing ratios may correspond to one combination pattern of the t / v value and the various operation state data.

Taking a mixed refrigerant in which three types of refrigerants a, b, and c are mixed as an example, the mixing ratio of the mixed refrigerant with respect to a certain combination pattern of the t / v value and the various operating state data is shown. (A: b: c) is 2: 3: 5,
There are cases where two types of 4: 1: 5 correspond. In such a case, when an input pattern corresponding to the two different mixing ratios is input to the neural network 41, it is not known which of the two different mixing ratios is output. An incorrect mixture ratio may be calculated.

The change in the mixing ratio of the mixed refrigerant is largely due to leakage of the refrigerant sealed in the refrigerator. It can be considered that this leakage is more likely to occur for a refrigerant having a lower evaporation temperature, that is, for a refrigerant that evaporates more easily. That is, the refrigerant having the lowest evaporation temperature among the refrigerant mixtures in which the three types of refrigerants a, b, and c are mixed is defined as a, and the mixing ratio (a: b: c) of the mixed refrigerant in the initial state is 3: 3: 4. If the ratio of the refrigerant a to the entire mixed refrigerant is,
It can be expected that the probability is 3/10 or less.

Therefore, different two patterns for one combination of the t / v value and the above-mentioned various operation state data are used.
If it is known from experiments or the like that the mixing ratios of the types correspond to each other, the ratio of the refrigerant that easily leaks to the initial state among the two different mixing ratios for the one combination pattern is small. It is preferable to calculate such a mixture ratio.

Specifically, for a certain input pattern, 2
If the two types of mixing ratios correspond to each other, the number of times of learning of the neural network using the mixing ratio such that the ratio of the refrigerant that easily leaks to the initial state among the two different types of mixing ratios becomes smaller, Is made larger than the number of times of learning of the neural network using.

Alternatively, of the two different mixing ratios, only the mixing ratio that reduces the ratio of the refrigerant that easily leaks to the initial state is used for learning the neural network, and the other mixing ratio is not used for learning. To In this case, the mixture ratio not used in the learning is stored in a memory as a second candidate of the mixture ratio used in the learning, and the mixture ratio used in the learning (hereinafter, referred to as a second mixture) is stored from a neural network. When a mixture ratio of one candidate is output, it is understood that the mixture ratio of the second candidate exists. Then, the expansion valve 4 is controlled assuming that the mixture ratio has changed to the mixture ratio of the first candidate, and if a good result is not obtained as a result, the mixture ratio of the second candidate is adopted.

FIGS. 5 and 6 show a refrigerant flow control processing procedure by the vapor compression refrigerator.

First, it is determined whether or not the notification means 108 of the refrigerator is operating (step S1). If the notification unit 108 is not operating, it is determined whether the operation mode of the refrigerator is set to the cooling operation mode or the heating operation mode, and the operation of the refrigerator is started in the set operation mode. Is performed (step S3).

When the operation mode is the cooling operation mode,
The indoor heat exchanger 1 is specified as an evaporator, and in the case of the heating operation mode, the outdoor heat exchanger 2 is specified as an evaporator (step S5). Here, the case where the operation mode is set to the cooling operation mode and the indoor heat exchanger 1 is specified as the evaporator will be described.

Next, the timing signal generator 102 is activated (step S7). As a result, the timing signal is output from the timing signal generator 102 at intervals of 30 seconds. Next, the control parameter of the electronic expansion valve 4 is set to an initial value in the case of a non-superheat state at the time of starting the compressor (step S9).

Thereafter, when a timing signal is input from the timing signal generator 102 (step S 11),
The electronic expansion valve 4 is controlled (Step S12). In control of the electronic expansion valve 4, it is currently set, using the control parameter values against the non-overheating of the compressor startup,
The degree of opening and closing of the electronic expansion valve 4 is controlled.

The evaporator outlet temperature detected by the second temperature detecting means 11 is taken in and stored in the temperature data storage section 103 (step S13). Next, the current detected refrigerant temperature and the previous detected refrigerant temperature are read from the temperature data storage unit 103, and the transition temperature calculating unit 104 operates the electronic expansion valve 4 between the last time and the present time.
Is calculated (step S15).

Then, the t / v value calculated in step S 15 by the mixing ratio calculation means 107 , the evaporator suction air temperature, the set air flow rate, and the electronic expansion valve 4 stored in the operating state storage unit 106. Based on the degree of opening and closing, the presence or absence of an overheat state at the evaporator outlet, and the drive frequency of the compressor 3, the mixing ratio of the enclosed mixed refrigerant and the refrigerant circulation amount are calculated (step S17).

Next, the mixture ratio calculated in step S17 is compared with the previous mixture ratio stored in the mixture ratio storage unit 108 to determine whether or not the mixture ratio has changed (step S19). ).

If the mixture ratio changes, step S1
7 is stored in the mixing ratio storage unit 108 as the current mixing ratio of the refrigerant mixture, and the refrigerant circulation amount calculated in step S17 is stored as the current refrigerant circulation amount in the mixing ratio storage unit 108. 108 (step S2
1). Then, the control parameter value for the non-superheated state at the time of starting the compressor, the control parameter value of the electronic expansion valve 4 with respect to the current mixing ratio of the refrigerant mixture is read from the ROM 110, and the read control parameter value is added to the read value. Is reset (step S21). Next, it is determined whether or not the currently calculated mixture ratio has changed from the initial mixture ratio by a predetermined allowable range or more (step S2).
5). This allowable range is determined in advance by an experiment, and RO
It is stored in M110.

If the currently calculated mixture ratio has changed by more than the allowable range with respect to the initial mixture ratio, the notification means 109 of the refrigerator is operated (step S29), and the operation of the refrigerator is stopped. Further, the current mixing ratio and the refrigerant circulation amount are displayed on the display of the operation display unit 111.

When it is determined in step S19 that the mixture ratio has not changed, or in step S25
If it is determined that the mixture ratio calculated this time does not change from the initial mixture ratio by more than the allowable range, the process proceeds to step S27.

In step S27, the above-mentioned step S15
It is determined whether or not the t / v value calculated in the step has increased by a certain value or more compared to the t / v value calculated last time. If the t / v value calculated this time has not increased by a certain value or more compared to the t / v value calculated last time, the process returns to step S11 to wait for the input of a timing signal from the timing signal generation unit 102. State. Then, when the timing signal is input from the timing signal generator 102, the processing of steps S12 to S27 is executed again.

If the t / v value calculated this time has increased by a certain value or more compared to the t / v value calculated last time,
The transition temperature calculation means 104 determines that the evaporator outlet temperature detected this time is the transition temperature to the overheat state (step S31). The control parameter value of the electronic expansion valve 4 is a control parameter value used after the compressor is overheated when the compressor is started, and the control parameter value of the electronic expansion valve 4 with respect to the current mixing ratio of the refrigerant mixture is the ROM1.
10, and the control parameter value is reset to the read value (step S33).

Thereafter, when a timing signal is input from the timing signal generator 102 (step S35), the evaporator outlet temperature detected by the second temperature detector 11 is taken in and stored in the temperature data storage 103. (Step S37).

The expansion valve of the evaporator is controlled by superheat control (step S38). In this superheat control,
Based on the evaporator outlet temperature detected by the second temperature detecting means 11 and the transition temperature obtained in step S31, the current superheat degree SH of the evaporator (SH = current evaporator outlet temperature-transition temperature) and Deviation e (= S) from target superheat degree SHo (in this embodiment, SHo is set to 4 ° C.)
Ho-SH) is required. And the obtained deviation e
The valve operation amount dv of the electronic expansion valve 4 is determined based on the currently set control parameter value, and the degree of opening and closing of the electronic expansion valve 4 is controlled by the determined valve operation amount dv.

Next, the current detected refrigerant temperature and the previous detected refrigerant temperature are read from the temperature data storage unit 103, and the transition temperature calculating means 104 operates the electronic expansion valve 4 from the previous time to the current time. A ratio t / v value of the change amount t of the evaporator outlet temperature to v is calculated (step S3).
9).

Then, the mixture ratio calculating means 106
The t / v value calculated in step S39, the evaporator suction air temperature stored in the operation state storage unit 106,
Based on the set air flow, the degree of opening and closing of the electronic expansion valve 4, the presence or absence of an overheat state at the evaporator outlet, and the drive frequency of the compressor 3, the mixing ratio of the enclosed mixed refrigerant and the refrigerant circulation amount are calculated (step S41).

Next, the mixture ratio calculated in step S41 is compared with the mixture ratio stored in the mixture ratio storage unit 108, and it is determined whether or not the mixture ratio has changed (step S43).

If the mixture ratio has changed, step S4
1 is stored in the mixture ratio storage unit 108 as the current mixture ratio of the refrigerant mixture, and the refrigerant circulation amount calculated in step S41 is stored as the current refrigerant circulation amount in the mixture ratio storage unit 108. 108 (step S4
5). Then, the control parameter of the electronic expansion valve 4 for the current mixing ratio of the mixed refrigerant is read from the ROM 110, and the control parameter value is reset to the read value (step S47). Next, it is determined whether or not the currently calculated mixture ratio has changed by more than a preset allowable range with respect to the initial mixture ratio (step S49).

If the currently calculated mixture ratio has changed by more than the allowable range with respect to the initial mixture ratio, the notification means 109 of the refrigerator is operated (step S29), and the operation of the refrigerator is stopped. Further, the current mixing ratio and the refrigerant circulation amount are displayed on the display of the operation display unit 111.

When it is determined in step S43 that the mixture ratio has not changed, or in step S49.
If it is determined in step that the currently calculated mixture ratio has not changed by more than the allowable range with respect to the initial mixture ratio, the process proceeds to step S51.

In step S51, it is determined whether a command to stop the operation of the refrigerator has been input. When the operation stop command of the refrigerator is input, the operation of the refrigerator is stopped, and this processing ends.

When the operation stop command of the refrigerator is not input, it is determined whether or not the compressor 3 is stopped (step 53). If the compressor 3 is not stopped, the process returns to step S35, and the timing signal generator 10
It is in a state of waiting for the input of the timing signal from the second. Then, when the timing signal is input from the timing signal generation unit 102, the processing after step S37 is executed again.

When it is determined in step 53 that the compressor 3 has stopped, it is determined whether a restart command for the compressor 3 has been input (step S55). When the restart instruction of the compressor 3 has been input, the process returns to step S7. When the restart instruction of the compressor 3 has not been input, the process returns to step S51.

As described above, in this embodiment, in the vapor compression refrigerator in which the non-azeotropic refrigerant mixture is enclosed,
Since a change in the mixing ratio due to refrigerant leakage is detected and optimal refrigerant flow control is performed, a decrease in refrigerator performance can be suppressed. In addition, since the transition temperature of the evaporator to the overheated state is accurately detected, and the control parameters can be adjusted by distinguishing between the non-superheated state and the after-overheated state at the time of starting the compressor, a high-precision refrigerant flow rate can be obtained. Control can be performed.

Further, in this embodiment, since it is reported that the mixture ratio of the mixed refrigerant is largely changed compared to the initial mixture ratio, it is necessary to know that it is necessary to refill the refrigerant by a service person. Can be. Also, at this time, since the mixture ratio of the refrigerant and the refrigerant circulation amount are displayed, the amount of the reduced refrigerant among the refrigerants contained in the mixed refrigerant is determined from these information. Therefore, when refilling the refrigerant, the reduced refrigerant can be replenished by the reduced amount,
Refilling of the refrigerant can be performed accurately and efficiently.

In the above embodiment, a neural network is used to determine the mixture ratio of the mixed refrigerant.
The mixing ratio of the mixed refrigerant may be obtained by another method such as fuzzy inference.

[0097]

According to the present invention, in a vapor compression refrigerator in which a non-azeotropic mixed refrigerant is sealed, the mixing ratio of the mixed refrigerant can be calculated based on the change in the evaporator outlet temperature. Thus, optimal flow rate control of the refrigerant becomes possible. Therefore, even when the mixture ratio of the mixed refrigerant changes, it is possible to suppress a decrease in refrigerator performance.

Further, according to the present invention, when the mixture ratio of the mixed refrigerant greatly changes from the initial mixture ratio due to refrigerant leakage, refilling of the refrigerant can be promoted. And
Refilling of the refrigerant can be performed accurately and efficiently.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a refrigerant circuit of a vapor compression refrigerator.

FIG. 2 is a graph showing an ideal refrigerant temperature change inside an evaporator using a non-azeotropic mixed refrigerant.

FIG. 3 is a block diagram showing an electrical configuration of the vapor compression refrigerator.

FIG. 4 is a schematic diagram showing a configuration of a neural network which is a main part of a mixture ratio calculating unit.

FIG. 5 is a flowchart illustrating a refrigerant flow control processing procedure.

FIG. 6 is a flowchart illustrating a refrigerant flow control processing procedure.

FIG. 7 is a schematic diagram showing a refrigerant circuit of a conventional vapor compression refrigerator.

FIG. 8 is a graph showing ideal refrigerant temperature changes inside an evaporator using a single refrigerant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Indoor heat exchanger 2 Outdoor heat exchanger 3 Compressor 4 Electronic expansion valve 5 Outdoor unit 6 Indoor unit 7 Refrigerant piping 8 Piping 9 Four-way valve 10 1st temperature detection means 11 2nd temperature detection means 12 3rd temperature detection means 12 Fourth temperature detection unit 101 control unit 102 timing signal generation unit 103 temperature data storage unit 104 transition temperature calculation unit 105 superheat degree calculation unit 106 operating state storage unit 107 mixing ratio calculation unit 108 mixing ratio storage unit 109 notification unit 110 ROM

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ichiro Uemura 2-5-1-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-6-101911 (JP, A) JP JP-A-6-147606 (JP, A) JP-A-8-61794 (JP, A) JP-A-8-86545 (JP, A) JP-B 5-66503 (JP, B2) JP-B 5-45867 (JP) , B2) (58) Field surveyed (Int. Cl. ⁶ , DB name) F25B 1/00 F25B 13/00 F25B 49/02

Claims (3)

(57) [Claims] 1. A vapor compression refrigerator in which a mixed refrigerant containing two or more kinds of refrigerants is enclosed in a refrigeration cycle including a compressor, a condenser, an expansion valve and an evaporator, wherein the expansion valve is provided at regular intervals. Calculating means for calculating the mixing ratio of the mixed refrigerant based on data including the amount of change in the detected refrigerant temperature near the refrigerant discharge side of the evaporator with respect to the manipulated variable of the evaporator; and the mixing ratio of the mixed refrigerant calculated by the calculating means. Control means for controlling the degree of opening and closing of the expansion valve based on the control information. 2. A vapor compression refrigerator in which a mixed refrigerant containing two or more types of refrigerant is filled in a refrigeration cycle including a compressor, a condenser, an expansion valve, and an evaporator, wherein the expansion valve is provided at regular intervals. Calculating means for calculating the mixing ratio of the mixed refrigerant based on data including the amount of change in the detected refrigerant temperature near the refrigerant discharge side of the evaporator with respect to the manipulated variable of the evaporator; based on the mixing ratio of the mixed refrigerant calculated by the calculating means Control means for controlling the degree of opening and closing of the expansion valve, and when the mixture ratio of the mixed refrigerant calculated by the calculation means has changed by a predetermined amount or more with respect to the initial mixture ratio, the mixing ratio of the mixed refrigerant is A vapor compression refrigerating machine comprising: means for informing that the mixture ratio of the refrigerant mixture has changed greatly as compared with the initial mixture ratio, and a mixture ratio of the mixed refrigerant calculated by the calculation means. 3. A main part of the calculating means is a neural network.
2. A structure comprising a work.
3. The vapor compression refrigerator according to any one of claims 2 and 3.