JPH04281161A - Refrigerating plant - 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]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stage refrigeration system having a refrigeration evaporator and a freezing evaporator.

0002

BACKGROUND ART FIG. 1 is an overall configuration diagram of a refrigeration system according to the present invention, which will be described later.Excluding the electric circuit part, the refrigeration cycle diagram is the same as that of a conventional refrigeration system. , will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a high-stage compressor, and the discharged high-temperature, high-pressure gas refrigerant is condensed in a condenser 2, and then some of the refrigerant passes through a first electromagnetic valve 3 and then passes through a first throttle. The pressure is reduced in the device 4, evaporated in the first evaporator 5, and returned to the high-stage compressor 1. The first evaporator 5 is housed in, for example, a refrigerator showcase (not shown), and the evaporation temperature here is, for example, -10°C and the internal temperature is 0°C.

[0003] Reference numeral 6 denotes a first bypass circuit which is connected in this order to a second electromagnetic valve 7, a second throttle device 8, a second evaporator 9, and a low-stage compressor 10; communicates between the condenser 2 and the first solenoid valve 3, and the other end communicates with the first evaporator 5.
The remaining refrigerant of the refrigerant condensed in the condenser 2 passes through the second solenoid valve 7.
After being depressurized by the second expansion device 8 and evaporated by the second evaporator 9, it is sucked into the low-stage compressor 10.

The temperature of the refrigerant discharged from the low-stage compressor 10 rises due to the compression action, but it mixes with the low-temperature gas refrigerant exiting the first evaporator 5 and is sucked into the high-stage compressor 1. be done.

Reference numeral 11 denotes a second detour circuit equipped with a check valve 12 for preventing refrigerant from flowing backward from the discharge side to the suction side of the low-stage compressor 10 while the low-stage compressor 10 is in operation. When the low-stage compressor 10 abnormally stops, the refrigerant is allowed to flow around it.

[0006] The second evaporator 9 is housed in, for example, a refrigeration showcase (not shown), and the evaporation temperature here is, for example, -40°C.

A first controller 13 detects the ambient air temperature of the first evaporator 5 and closes the first solenoid valve 3 when the temperature drops below a predetermined temperature (for example, -2° C. or below); 14
is a second controller that detects the ambient air temperature of the second evaporator 9 and closes the second electromagnetic valve 7 when the temperature falls below a predetermined temperature (for example, -22° C. or below).

Reference numeral 15 denotes a protection device for the low stage compressor 10, which detects, for example, the current of a motor (not shown) built in the low stage compressor, and when an abnormal flow value is reached, the low stage compressor is 10 is forcibly stopped.

Next, the operation will be explained. If the protection device 15 is activated and the low stage compressor 10 is stopped now,
The refrigerant avoids flowing into the low stage compressor 10 and flows through the second detour circuit 11.

However, if the ambient air temperature of the first evaporator 5 detected by the first controller 13 is equal to or higher than a predetermined value, the first solenoid valve 3 is open, and the first detour circuit 6 is opened. A sufficient amount of refrigerant is not secured. As a result, the cooling capacity of the second evaporator 9 decreases.

[0011]

[Problem to be Solved by the Invention] Since the conventional refrigeration system is constructed as described above, it is difficult to prevent the lower stage compressor 10
If the evaporator stops abnormally, the cooling capacity of the second evaporator 9, which is used for freezing, will be drastically reduced, causing serious damage such as melting of frozen foods and ice cream stored in the freezer showcase. There are challenges. Note that as an approximation technique, there is the specification of US Pat. No. 3,150,498.

[0012] This invention was made to solve the above-mentioned problems, and even if the lower stage compressor were to stop abnormally, it would be possible to supply sufficient refrigerant to the refrigeration evaporator and ensure reliability. The purpose is to obtain a refrigeration system that can be improved.

[0013]

[Means for Solving the Problems] A refrigeration system according to the present invention includes a solenoid valve that is provided upstream of an evaporator for refrigeration and that closes in response to an operation signal of a protection device for a low-stage compressor, and A controller equipped with a controller that detects the ambient air temperature of the refrigeration evaporator or the temperature or pressure of a corresponding location when the device operates, and controls the opening and closing of the solenoid valve according to this detected value. It is.

[0014]

[Operation] When the protection device for the low-stage compressor of the present invention is activated, or when this protection device is activated, the ambient air temperature of the refrigeration evaporator, the predetermined temperature at the corresponding location,
When either of the pressures is detected by the controller and the detected value exceeds a predetermined value, the solenoid valve is closed to prevent the refrigerant from flowing into the refrigeration evaporator. Ensure that sufficient refrigerant is supplied to the container.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the refrigeration system of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of one embodiment, and the refrigeration cycle in FIG.
This is as described in the ``Prior Art'' column, and the refrigerant cycle will not be explained again here, and the explanation will mainly be based on the electric circuit diagram.

In FIG. 1, 13a is a contact point of the first controller 13, which is closed when the detected value of the ambient air temperature of the first evaporator 5 by the first controller 13 is above a predetermined value. There is.

Further, 15a is a contact point of the protection device 15 of the low-stage compressor 10, which opens when the protection device 15 operates. 3a is a coil of the first electromagnetic valve 3. These contacts 13a, 15a and coil 3a are connected to power lines L1 and L.
The two are connected in series.

Next, the operation will be explained. Now, when the protection device 15 operates, the contact 15a opens. Therefore, regardless of whether the contact 13a is open or closed, the first solenoid valve 3
The coil 3a is demagnetized. As a result, the first solenoid valve 3
is closed, and all the refrigerant is supplied to the second evaporator 9.

FIG. 2 is an overall configuration diagram of a refrigeration system according to a second embodiment of the present invention. In this FIG. 2, 16 detects the ambient air temperature of the second evaporator 9, and when it reaches a set value (for example, a set value that is the same as or higher than the set value of the second controller 14), the first This is a third controller for closing the electromagnetic valve 3.

16a in the electrical system of FIG.
is a contact point of the third controller 16, which opens when the third controller 16 detects a temperature equal to or higher than a set value. Contact 15
Contact 13a and coil 3a1 are connected to the parallel circuit of a and contact 16a.
are connected in series. The other configurations are the same as those in FIG. 1, so explanations will be omitted.

Next, the operation of the embodiment shown in FIG. 2 will be explained. Now, the protection device 15 is activated and the third controller 1
When the detected temperature of No. 6 is equal to or higher than the set value, the contacts 15a and 16a are opened. Therefore, the coil 3a1 of the first electromagnetic valve 3 is demagnetized regardless of whether the contact 13a is open or closed. As a result, the first solenoid valve 3 is closed and all the refrigerant is supplied to the second evaporator 9.

FIG. 3 is a refrigeration cycle diagram showing a refrigeration system according to a third embodiment of the present invention, and FIG. 4 is a main part electric circuit of FIG. 3. First, in the refrigeration cycle diagram of FIG.
first solenoid valves 3a to 3c, first throttle devices 4a to 4c,
First evaporators 5a to 5c are connected in parallel. Also,
A plurality of first controllers 13a to 13c are provided so as to correspond to the first evaporators 5a to 5c, respectively.

Furthermore, in the circuit diagram of FIG. 4, 16a1
- 16a3 are contacts of the third controller 16, and these contacts 16a1 - 16a3 open at the same or higher temperature than the set value of the second controller, and the contacts 16a1 - 16a3 open at a temperature equal to or higher than the set value of the second controller.
It is set so that there is a slight temperature difference between the open circuit temperature value of 16a3. 15a1 to 15a3 are protective devices 1
5 contacts, and each opens when the protection device 15 operates.

A contact 13a1 and a coil 3a1 are connected in series to a parallel circuit of contacts 15a1 and 16a1. Contacts 15a2, 15a3, 16a2, 16a3,
The connection relationships between coils 13a2 and 13a3 and coils 3a2 and 3a3 are also the same. The other configurations are the same as those in FIG. 2, so their explanation will be omitted.

Next, the operation of the third embodiment shown in FIGS. 3 and 4 will be explained. When the protection device 15 is activated, its contacts 15a1 to 15a3 are opened. When the temperature detected by the third controller 16 is relatively low, the contact 16a1
Only one of the first solenoid valves 3a to 3c is closed.

Furthermore, when the temperature detected by the third controller 16 rises, the contacts 16a2 and 16a3 are sequentially opened, and the remaining first electromagnetic valves 3b and 3c are sequentially closed.

In this way, the first evaporators 5a to 5c
Depending on the food being cooled, stop cooling one by one,
The cooling capacity of the second evaporator 9 can be maintained within the necessary limit. When there are multiple refrigeration side evaporators as in the embodiments shown in Figs. 3 and 4, deterioration of foods such as meat and fresh fish can be prevented by stopping the refrigerant supply to each evaporator in sequence according to the items stored in each evaporator. It has the effect of being able to keep it to a minimum.

[0028]

As described above, according to the present invention, a low-stage compressor of a two-stage refrigeration system having a high-stage compressor, a low-stage compressor, and an evaporator for refrigeration and freezing is provided. A bypass circuit is installed in the refrigeration side, and when this low-stage compressor protection device is activated and the low-stage compressor stops, refrigerant is supplied to the refrigeration side evaporator immediately or depending on the cooling status of the refrigeration side. Since the structure is designed to prevent
Definite damage to stored items such as melting due to temperature rise on the freezing side can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a refrigeration system according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a refrigeration system according to a second embodiment of the present invention.

FIG. 3 is a refrigeration cycle diagram of a refrigeration system according to a third embodiment of the present invention.

FIG. 4 is an electrical circuit diagram of main parts of the refrigeration system shown in FIG. 3;

[Explanation of symbols]

1 High-stage compressor 2 Condenser 3, 3a to 3c First solenoid valve 4, 4a to 4c First throttle device 5, 5a to 5c First evaporator 6 First detour circuit 7 Second solenoid Valve 8 Second throttling device 9 Second evaporator 10 Low-stage compressor 11 Second bypass circuit 12 Check valves 13, 13a to 13c First controllers 13a, 13a
1 to 13a3 First controller contact 14 Second
Controller 15 Protective devices 15a, 15a1 to 15a3 Protective device contacts 1
6 Third controller 16a Third controller contacts

Claims (1)

[Claims] Claim 1: A refrigeration cycle comprising a high-stage compressor, a condenser, a first electromagnetic valve, a first throttling device, and a first evaporator connected in sequence; a second throttle device, a second evaporator, and a second throttle device;
The first detour circuit includes a first detour circuit configured by sequentially connecting the low stage compressors, and a valve that blocks refrigerant flow from the discharge side to the suction side of the low stage compressor. a second detour circuit through which refrigerant flowing through bypasses the low-stage compressor; and a protection device that operates during abnormal operation of the low-stage compressor to stop the operation of the low-stage compressor. When the above protection device is activated or this protection device is activated and the above second
a controller that closes the first electromagnetic valve when an ambient temperature of the evaporator or a detected value of the temperature or pressure at a corresponding location exceeds a predetermined value.