JP2526988B2 - Refrigeration equipment - Google Patents

Description

The present invention relates to a refrigerating apparatus having a refrigerating cycle using a non-azeotropic mixed refrigerant in which R22 and another refrigerant are mixed and used at a pressure comparable to that of R12, for example. For example, it can be used for an air conditioner for automobiles, which has a large variation in load.

(Prior Art) Conventionally, in a vehicle air conditioner, a single refrigerant represented by R12 or an azeotropic mixed refrigerant such as R500 and R502 is mainly used. However, as a CFC ozone problem, it has recently been noted that CFCs such as R12 are depleting ozone. Therefore, it is required to use a refrigerant that does not destroy ozone.
Since R22 cannot be used due to its high pressure, it has been noted that R22 and other refrigerants are mixed to use a non-azeotropic mixed refrigerant used at the same pressure as R12. However, non-azeotropic mixed refrigerants are characterized by temperature changes during the evaporation and condensation processes, and when a refrigerant having such characteristics is used in a vehicle air conditioner, the blowing temperature varies as the evaporation temperature changes. There is a problem that it may be frosted or frost may be generated due to the temperature difference.

As a solution to such a problem, JP-A-60-1400
There is a refrigerating apparatus using a non-azeotropic mixed refrigerant disclosed in Japanese Patent Laid-Open No. 48. In this refrigeration system, the heat source side heat exchanger that serves as an evaporator during the heating operation, the refrigerant flowing through the heat exchanger,
A fixed pressure reducing means for reducing the pressure corresponding to the temperature gradient of the refrigerant is provided.

(Problems to be Solved by the Invention) Although the refrigerating apparatus disclosed in Japanese Patent Laid-Open No. 60-140048 is effective as a household refrigerating apparatus in which load fluctuation is small,
When the load fluctuation is large, for example, when used as an air conditioner for automobiles, it is not enough to dispose the fixed pressure reducing means as described above, and when the load is large, the pressure reducing means is It causes people to reduce their freezing capacity.

(Means for Solving the Problem) The present invention relates to a refrigeration apparatus that includes a compressor, a condenser, a main pressure reducer, and at least two evaporators arranged in series, and uses a non-azeotropic mixed refrigerant. Detecting the state (for example, temperature or pressure) of the refrigerant returning to the compressor between the compressor and the evaporator adjacent to the compressor, and the auxiliary pressure reducer disposed between the evaporators. A first detector that
Second for detecting the state (for example, temperature or pressure) of the refrigerant between the main decompressor and the evaporator adjacent to the main decompressor
And a detector, the main decompressor responds to a signal from the first detector to variably control the refrigerant throttle amount, and the auxiliary decompressor responds to a signal from the second detector. In this way, the refrigerant throttle amount is variably controlled.

In the refrigeration apparatus of the present invention, an auxiliary detector is provided adjacent to the auxiliary pressure reducer for detecting the state of the refrigerant (eg, temperature or pressure) after passing through the auxiliary pressure reducer. The auxiliary decompressor variably controls the refrigerant throttle amount in response to a signal from the compressor.

Further, the present invention provides the refrigeration apparatus according to the second aspect.
The detector of (1) outputs a signal for restricting the flow of the refrigerant to the auxiliary pressure reducer when the temperature of the refrigerant is equal to or lower than a predetermined temperature.

(Operation) In the first invention of the present application, the main decompressor variably controls the throttle amount of the entire refrigerant by receiving a signal from the first detector,
The auxiliary decompressor should only be activated when the load is light. The magnitude of the load is detected by the second detector.

In the second aspect of the present invention, the auxiliary pressure reducer more finely controls the throttle amount of the refrigerant by the signal from the auxiliary detector.

In the third aspect of the present invention, the second detector activates the auxiliary pressure reducer particularly by detecting the cooling temperature.

(Embodiment) Referring to FIG. 1, there is shown a schematic configuration of a refrigerating apparatus which is an embodiment of the present invention. FIG. 2 is a flow chart for explaining the processing in the control unit in this refrigeration system.

In FIG. 1, when the power switch 11 is turned on, the refrigeration system becomes operable. At this time, the electromagnetic clutch 1a is connected by a signal from a room temperature sensor (not shown), and the compressor 1 is connected to the automobile engine (Fig. Driven by (not shown), the non-azeotropic mixed refrigerant is compressed. The compressed refrigerant is heat-exchanged and condensed in the condenser 2 and reaches the receiver 3,
Here, the liquid refrigerant that is separated into gas and liquid and that is discharged from the receiver 3 is expanded by the main decompressor 4 and exchanges heat with the surrounding heat in the evaporators 5a, 5b, 5c to evaporate and cool the surrounding air. , The evaporated refrigerant is compressed by the compressor 1 again,
Repeat the refrigeration cycle.

In the illustrated embodiment of the invention, three evaporators 5a, 5b,
A first variable resistance valve 6a in which 5c are arranged in series, and a first valve actuating coil 6m constituting an auxiliary pressure reducer is provided between the first evaporator 5a and the second evaporator 5b. Is placed, and also
Between the 2nd evaporator 5b and the 3rd evaporator 5c, the 2nd variable resistance valve 6b provided with the 2nd valve actuation coil 6n which comprises an auxiliary pressure reducer is arranged. Further, a first temperature sensor 7a and a second evaporator 5b which constitute a second detector for detecting the temperature of the refrigerant between the first evaporator 5a and the main pressure reducer 4.
A second temperature sensor 7b forming an auxiliary detector for detecting the temperature at the inlet of the third evaporator, a third temperature sensor 7c forming an auxiliary detector for detecting the temperature at the inlet of the third evaporator 5c, Also, a fourth temperature sensor 7d, which constitutes a first detector for detecting the temperature of the refrigerant between the third evaporator 5c and the compressor 1, is provided. The signals from these temperature sensors 7a, 7b, 7c, 7d and the room temperature sensor (not shown) are respectively input to the control unit 10, and the control unit 10 is controlled.
Reference numeral 10 controls the operation of the main pressure reducer 4, the first and second variable resistance valves 6a and 6b, and the electromagnetic clutch 1a.

When it is necessary to cool the room strongly, that is, when the load in the room is high, the evaporation temperature is high and there is no fear of frosting. Therefore, the first and second variable resistance valves
The refrigeration cycle is performed with 6a and 6b being fully opened. This refrigeration cycle is as shown in the T-S diagram shown in FIG. In the non-azeotropic mixed refrigerant, even if the pressure (P) is constant and evaporated, the low boiling point refrigerant gradually evaporates, so that the evaporation temperature (T) gradually increases.

The load in the room decreased and the evaporation temperature began to decrease.
When the temperature sensor 7a of FIG. 3 detects that the inlet temperature of the evaporator 5a is below a certain set temperature (for example, 0 ° C.), the control unit 10 receives the signal from the first temperature sensor 7a and A signal is applied to the valve operating coil 6m of the first variable resistance valve 6a.
To squeeze. The variable resistance valve 6a operates so as to reduce the pressure until the second temperature sensor 7b detects a certain set temperature (for example, 0 ° C.). Second and third temperature sensors 7b, 7c
And the second variable resistance valve 6b have the same relationship as described above, and the third temperature sensor 7c sets a certain set temperature (for example, 0
The second variable resistance valve 6b is squeezed to reduce the pressure until (.degree. C.) is detected. Fourth temperature sensor 7d constituting the first detector
Detects the degree of superheat at the outlet of the third evaporator 5c,
To control the throttle amount of the entire refrigerant. Thus, the magnitude of the load is detected by the first temperature sensor 7a which is the second detector. When the load is large, the main decompressor 4 controls the throttle amount of the refrigerant exclusively by the signal from the fourth temperature sensor 7d, which is the first detector, to form the auxiliary decompressor. The variable resistance valves 6a and 6b are fully opened. When the load is small, the first and second variable resistance valves 6a and 6b variably control the throttle amount of the refrigerant by the first temperature sensor 7a. The second and third temperature sensors 7b and 7c output signals for the first and second variable resistance valves 6a and 6b to variably and delicately control the throttle amount of the refrigerant.

The refrigeration cycle when the first and second variable resistance valves 6a and 6b are throttled is shown in the TS diagram of FIG. 3 (b). The evaporation temperature that rises in the process of evaporation of the refrigerant is
It will be understood that the first variable resistance valve 6a is lowered over two times, as indicated by 9a, and by the second variable resistance valve 6b, as indicated by 9b. Ah

In this way, by making the evaporation temperature of the non-azeotropic mixed refrigerant almost constant, it is possible to eliminate variations in the blowout temperature, and even when the indoor load is reduced and frost is likely to occur, the variable resistance valve Is controlled to control the flow rate of the refrigerant in the evaporator to keep the evaporation temperature substantially constant, whereby frost formation can be prevented.
Also, it can be dealt with by fully opening the second variable resistance valves 6a, 6b.

Next, the control operation of the control unit 10 will be described with reference to FIG. Control Yunitsuto 10 includes a microcomputer, detects the temperature t _7a by the temperature sensor 7a at step 101
And the frost point temperature are compared, and if the detected temperature t _7a is higher than the frost point temperature, it is determined in step 102 whether the indoor load is maximum. If it is the maximum, the routine goes to step 103 to fully open the first variable resistance valve 6a.
If it is not the maximum, the routine proceeds to step 104, where it is judged whether the difference between the temperature t _7b detected by the temperature sensor 7b and the temperature t _7a detected by the temperature sensor 7a is smaller than the allowable value (ε) of the temperature difference. Then, if it is smaller, the variable resistance valve 6a is fully opened by going to step 103, and if it is not smaller, the variable resistance valve 6a is throttled by going to step 105. If the temperature t _7a detected by the temperature sensor 7a is lower than the frost point temperature, step 1
Go to 05 and throttle the variable resistance valve 6a.

The explanation for FIG. 2 described above is based on the first variable resistance valve.
It describes how to control 6a, but second
The control of the variable resistance valve 6b is also performed in the same manner.
In that case, the temperatures detected by the temperature sensors 7b and 7c are used.

Further, although the above embodiment is a receiver cycle, the present invention can be applied to an accumulator cycle.

(Effect of the invention) According to the present invention, the magnitude of the load is detected by the second detector, and when the load is large, the auxiliary decompressor is fully opened and the signal from the first detector is detected. The main pressure reducer is used to variably control the refrigerant throttle amount, and the auxiliary pressure reducer is activated only when the load is small.Therefore, the refrigeration capacity at high load is sufficient and the air conditioning at low load is performed. It is possible to prevent variations in the blowout temperature of the device and frost formation, and it is possible to bring such an advantage to the extremely simple and economical structure.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a refrigerating apparatus which is an embodiment of the present invention, FIG. 2 is a flow chart for explaining processing in a control unit in this refrigerating apparatus, and FIG. 3 is a non-azeotropic mixed refrigerant in a refrigerating cycle. To explain the change in evaporation temperature of T-
In the S diagram, (a) shows a refrigeration cycle in a state in which the variable resistance valve is fully opened, and (b) shows a refrigeration cycle in a state in which the variable resistance valve is narrowed. 1 ... Compressor, 1a ... Electromagnetic clutch, 2 ... Condenser, 3 ... Receiver, 4 ... Main decompressor, 5a, 5b, 5c ... Evaporator, 6a, 6b ... Variable resistance valve, 6m , 6n …… Valve actuating coil, 7a, 7b, 7c, 7d …… Temperature sensor, 10 …… Control unit, 11 …… Power switch.

Claims (3)

(57) [Claims] 1. A refrigeration system using a non-azeotropic mixed refrigerant, comprising a compressor, a condenser, a main decompressor, and at least two evaporators arranged in series, wherein a plurality of evaporators are arranged between the evaporators. An auxiliary decompressor provided, a first detector for detecting a state of refrigerant returning to the compressor between the compressor and the evaporator adjacent to the compressor, the main decompressor and the main Second for detecting the state of the refrigerant between the decompressor and the evaporator adjacent to the second
And a detector, the main decompressor responds to a signal from the first detector to variably control the refrigerant throttle amount, and the auxiliary decompressor responds to a signal from the second detector. The refrigerating apparatus is characterized by variably controlling the refrigeration amount. 2. An auxiliary detector is provided adjacent to the auxiliary pressure reducer for detecting the state of the refrigerant after passing through the auxiliary pressure reducer,
The refrigeration system according to claim 1, wherein the auxiliary pressure reducer variably controls the refrigerant throttle amount in response to a signal from the auxiliary detector. 3. The refrigerating apparatus according to claim 1, wherein the second detector outputs a signal to throttle the flow of the refrigerant to the auxiliary pressure reducer when the temperature of the refrigerant is equal to or lower than a predetermined temperature.