JPS61208473A - Refrigeration cycle device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a multi-type refrigeration system equipped with a refrigeration cycle in which a variable capacity compressor, a condenser, a plurality of parallel evaporators, etc. are connected in sequence. Related to cycle equipment.

[Technical background of the invention]

Generally, stores that sell fresh foods use showcases to display their products.

Some such showcases include a plurality of spaces to be cooled, that is, cooling chambers, and each cooling chamber is provided with a cooler (evaporator). FIG. 3 shows an example of a refrigeration cycle device mounted on such a showcase.

In the third factor, 1 is a variable capacity compressor, and this variable capacity compressor 1. Condenser 2. Liquid tank 3゜Solenoid shut-off valve 1
1. Expansion valve 12. ``A compressor 13., accumulator 4, etc. are connected in sequence, and the electromagnetic on-off valve 2 is connected to the series body of the electromagnetic on-off valve 11.expansion valve 12.evaporator 13.
1. Expansion valve 22. Evaporator 23 in series and electric switch 11 on/off valve 31. Expansion valve 32. The series bodies of the evaporators 33 are connected in parallel to form a refrigeration cycle.

The evaporators 13, 23.33 are arranged in each cooling chamber, and a temperature sensor 14.24.3 is installed in each cooling chamber.
There are 4. And solenoid on/off valve 11.21.31
is turned on and off (opened, opened) according to the temperature detected by the temperature sensor 14.24°34. In addition, an expansion valve 12. is installed on the refrigerant outlet side pipe of the evaporator 13.
22.32 temperature sensing cylinders 12a, 22a, 32a are installed.

Furthermore, a pressure sensor 5 is attached to the suction line, and the detection results of this pressure sensor 5 are sent to the inverter drive control circuit 6.
We are trying to supply it to This inverter drive control circuit 6 controls the output frequency of the inverter circuit 7 according to the detection result of the pressure sensor 5. The inverter circuit 7 supplies the drive motor of the compressor 1 with AC power having a frequency (and voltage) according to the control of the inverter drive control circuit 6 .

That is, as shown in FIG. 4, if the temperature in each cooling chamber is above the set value, both the electromagnetic on-off valves 11, 21 and 31 are turned on (opened), and the air is discharged from the compressor 1 and passed through the condenser 2. The refrigerant passes through the expansion valve 12.22°32 to the evaporator 13.2.
It flows into 3.33.

In this way, each cooling chamber is cooled by the evaporation action of the refrigerant in the evaporator 13, 23, 33. In this case, if the load is large, the suction pressure Ps increases, and conversely, if the load is small, the suction pressure PS decreases, and the output frequency of the inverter circuit 7 (hereinafter referred to as operating frequency F) changes accordingly.

In other words, the capacity of the compressor 1 changes. Furthermore, when the capacity of the compressor 1 changes, the degree of superheating (amount of superheat) of the refrigerant in the evaporator 13, 23, 33 tends to change, but the degree of superheating of the refrigerant remains constant due to the change in the opening of the expansion valves 12, 22, 32. control. For example, the evaporator 13
When the temperature in the cooling chamber in which the evaporator is installed falls to a value d°C lower than the set value, the electromagnetic on-off valve 11 is turned off (closed) and no refrigerant flows into the evaporator 13, and the cooling operation of that chamber is stopped. Interrupt. Thereafter, the temperature is adjusted by turning on and off the electromagnetic on-off valves 11, 21 and 31.

[Problems with background technology]

However, temperature control by turning on and off the electromagnetic on-off valves 11, 21, 31 has a disadvantage in that there is a large variation with respect to the set value. In particular, when a load change occurs in one cooling room, the capacity of the compressor 1 changes in other cooling rooms regardless of their own loads, and at this time, turning on and off the electromagnetic on-off valve effectively deals with the change in capacity. This results in large temperature changes.

[Purpose of the invention]

This invention was made in view of the above circumstances,
The purpose is to provide a highly reliable refrigeration cycle device that can maintain the temperature of each cooling space substantially constant regardless of changes in load.

[Summary of the invention]

This invention provides a temperature sensor that detects the temperature of a space to be cooled in which each evaporator is installed, and a refrigerant flow control valve that controls the flow rate of refrigerant to each evaporator. In addition to controlling the degree of superheating according to the temperature detected by each of the above-mentioned temperature sensors, there is also a means for detecting the overall degree of superheating of the refrigerant by each evaporator, and a means for controlling the capacity of variable capacity compression according to the detection result. It is something that

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. However, in the drawings, the same parts as in FIG. 3 are given the same reference numerals, and detailed explanation thereof will be omitted.

As shown in FIG. 1, on the refrigerant inflow side of the evaporator 13.23.33, a refrigerant flow control valve 15 is installed in place of the conventional electromagnetic on-off valve 11.21.31 and expansion valve 12.22.32.
．． 25.35 shall be provided. These refrigerant flow rate control valves can change their opening degree continuously, and also function as a pressure reducing device between the condenser 2 and each evaporator. Opening limiters 16, 26, and 36 are connected to the temperature sensors 14, 24, and 34, and these opening controllers are connected to the refrigerant flow rate control valves 15.
25. Connect the respective drive motors of 35. here,
The opening controllers 16, 26.36 are temperature sensors 14, 24.
．． Depending on the detected temperature of 34, the refrigerant flow control valve 15.25.
35, respectively.

Further, a conduit is provided between the liquid tank 3 and the suction line via a capillary tube 8, and a temperature sensor 9 is attached to this conduit. Additionally, the evaporator 13.23.3
A temperature sensor 10 is attached to the refrigerant outlet side conduit of No. 3. The temperature information detected by these temperature sensors 9 and 10 is supplied to the inverter drive control circuit 60. The inverter drive control circuit 60 detects the overall degree of superheating of the refrigerant in each evaporator based on the temperatures detected by the temperature sensors 9 and 10, and changes the output frequency, that is, the capacity, of the inverter circuit 7 according to the detected degree of refrigerant superheating. This controls the operating frequency F of the compressor 1.

Next, the operation of the above-described configuration will be explained with reference to the flowchart shown in FIG.

When the variable capacity compressor 1 is started, the variable capacity compressor 1
When the discharged refrigerant passes through the condenser 2, the refrigerant flow control valve 15.
25.35 into the evaporator 13°23.33. In this way, each cooling chamber is cooled.

Therefore, it is now assumed that the opening degree of the refrigerant flow rate control valve 15.25°35 and the capacity of the compressor 1 are each at their optimum values, and the refrigeration cycle is operating stably.

In this state, if the door of the cooling chamber of the evaporator 13 is opened, for example, the load increases and the temperature of the cooling chamber T
As a increases, the refrigerant in the evaporator 13 becomes easier to evaporate, and the degree of refrigerant superheating increases. At this time, the temperature sensor 14 detects the temperature Ta, and if the temperature Ta is higher than the set value TS, the opening controller 16 increases the opening of the refrigerant flow rate control valve 15. When the opening degree of the refrigerant flow control valve 15 increases, the refrigerant flow rate to the evaporator 13 increases, and the cooling capacity increases. In this way, when the cooling capacity increases, the temperature Ta
It is possible to suppress an increase in the temperature of the refrigerant, and furthermore, it is possible to suppress an increase in the degree of superheating of the refrigerant.

However, even with such opening adjustment, there may be cases where the cooling is insufficient and it is not possible to cope with the load. In this case, the degree of superheating of the refrigerant is still large, and in order to cope with this, the inverter drive control circuit 60
performs the following control. That is, the inverter drive control circuit 60 controls the temperature detected by the temperature sensor 9 (saturation temperature) Tsa
t and the detected temperature (suction temperature) To of the temperature sensor 10
The overall degree of refrigerant superheating SH (-To-Tset) is calculated by If it is smaller than SH8, the operating frequency F of the compressor 1 is lowered). However, the operating frequency F
If the amount increases, the capacity of the compressor 1 increases, the amount of refrigerant circulated increases, and together with the increase in the opening of the flow rate control valve 15, the cooling capacity increases.

Moreover, the degree of superheating of the refrigerant is stabilized.

In this way, the opening degree of the refrigerant flow control valve is adjusted according to load fluctuations to control the refrigerant flow rate to the evaporator, and the capacity of the compressor 1 is controlled according to the overall degree of refrigerant superheating. Therefore, the temperature of each cooling chamber can be maintained approximately constant while maintaining the balance of the refrigeration cycle. Moreover,
Only one valve is required for one evaporator (conventionally, two valves are required for one evaporator), which simplifies the configuration of the refrigeration cycle and reduces costs.

In the above embodiment, the refrigerant superheat degree is detected using two temperature sensors, but it may be detected from the suction temperature and suction pressure. In addition, the present invention is not limited to the embodiments described above, and as described above without changing the gist, according to the present invention, the temperature of the space to be cooled in which each evaporator is installed is detected. A temperature sensor is provided, and a refrigerant flow control valve is provided to control the refrigerant flow rate to each evaporator. A means for detecting the overall refrigerant superheat degree is provided, and a means for controlling the capacity of the variable capacity compressor according to the detection result is provided, so the temperature of each cooling space can be maintained approximately constant regardless of load fluctuations. It is possible to provide a refrigeration cycle device with excellent reliability.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention;
FIG. 2 is a flowchart for explaining the operation of the same embodiment, FIG. 3 is a diagram showing the overall configuration of the conventional device, and FIG. 4 is a diagram for explaining the operation of the conventional device. 1... variable capacity compressor, 2... condenser, 13.23
．． 33... Evaporator, 14.24.34... Temperature sensor, 15.25.35... Refrigerant flow rate control valve, 16.26.
36... Opening controller, 60... Inverter drive control circuit. Applicant's agent Patent attorney Takehiko Suzue Figure 2

Claims (1)

[Claims] In a refrigeration cycle device including a refrigeration cycle formed by sequentially communicating a variable capacity compressor, a condenser, and a plurality of parallel evaporators, the temperature of a space to be cooled in which each of the evaporators is installed is detected. a temperature sensor, a refrigerant flow control valve for controlling the flow rate of refrigerant to each of the evaporators, means for detecting the overall degree of superheating of the refrigerant by each evaporator, and adjusting the capacity of the variable capacity compressor according to the detection result. A refrigeration cycle device characterized by comprising: means for controlling.