JPH028660A - Freezer - Google Patents

Abstract

PURPOSE:To prevent a sucking for a high-stage compressor from being increased by a method wherein when a defrosting operation in carried out by changing- over a coolant circuit through a changing-over valve, coolant gas is simultaneously sucked from an evaporator to a low-stage compressor and a high-stage compressor so as to perform a simultaneous compression. CONSTITUTION:Gas of high temperature and high pressure compressed by a high-stage compressor through a solenoid valve 10, flows into an evaporator 9 so as to resolve frost adhered to the evaporator 9. In turn, gas of high temperature and high pressure compressed by a low-stage compressor 1 also passes through a four-way valve 14, passes a check valve 15 and a solenoid valve 10 and flows into the evaporator 9. Then, coolant gas evaporated by the evaporator 9 passes through the low-stage compressor 1, the check valve 16 and the four-way valve 14, is sucked simultaneously into the high-stage compressor 2 and further it is simultaneously compressed. During this defrosting operation, since the sucking circuit of the high-stage compressor 2 is the same as the sucking circuit of the low-stage compressor 1, even if the pressure of the evaporator 9 increases during defrosting operation, the sucking pressure of the high- stage compressor 2 is not increased and a heating operation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a refrigerating machine that compresses refrigerant gas in two stages and then liquefies it, and particularly relates to a refrigerant circuit switching device.

[Conventional technology]

Figure 3 is a system diagram showing a conventional two-stage cold compression type refrigerator. A stop valve, 4 is a condenser that liquefies high-pressure gas, 56 is a solenoid valve that supplies and stops refrigerant, 1 and 8 are expansion valves that control refrigerant gas, 9 is an evaporator that evaporates refrigerant, and 10 is for defrosting. A solenoid valve, 11 a suction pressure regulating valve for preventing an increase in suction pressure, and 12 and 13 a blower.

Next, the operation will be explained.

First, when performing cooling, refrigerant gas sucked from the evaporator 9 through the suction pressure regulating valve 11 is compressed by the low-stage compressor 1 and becomes high-pressure gas. This high-pressure gas is then sucked into the high-stage compressor 2 and compressed again, but at this time, this high-pressure gas is cooled through the low-stage gas cooling solenoid valve 5 and the cooling expansion valve 8. It is cooled by the refrigerant liquid and sucked into the high-stage compressor 2. The high-pressure gas compressed by the high-stage compressor 2 is liquefied by the condenser 4, passed through the direct magnetic valve 6, and further depressurized by the expansion valve 7, becoming a refrigerant that is easily evaporated. . Next, this refrigerant is sucked into the evaporator 9, evaporated, and returned to the original refrigerant gas. After fc, the refrigerant is sucked into the low-stage compressor 1 through the suction pressure regulating valve 11 again. Note that the blowers 12 and 13 are used to exchange heat between the refrigerant and air.

Next, when defrosting is performed, the high-temperature, high-pressure gas compressed by the high-stage compressor 2 is made to flow into the evaporator 9 through the solenoid valve 1o to thaw the frost attached to the evaporator 9. . Next, the refrigerant gas sucked from the evaporator 9 through the suction pressure regulating valve 11 is compressed by the low-stage compressor 1, and the high-pressure gas compressed by the low-stage compressor 1 is used for cooling the low-stage gas. It is cooled by the refrigerant liquid that has passed through the electromagnetic valve 5 and the cooling expansion valve 8, and is compressed again by the high-stage compressor 2.

Note that during this defrosting, the blower 12 and the solenoid valve 6 are in a stopped state.

[Problem to be solved by the invention]

Since the conventional two-stage compression type refrigerator is configured as described above, when the evaporator pressure increases during defrosting, the suction pressure of the high-stage compressor increases, causing overheating operation. To prevent this, it is necessary to keep the suction pressure of the high-stage compressor constant, and it is necessary to install a suction pressure regulating valve or provide resistance with an orifice.
There were problems such as low defrosting ability.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain a refrigerator that can prevent an increase in suction pressure of a high-stage compressor.

[A shortcut to solving problems]

In the refrigerator according to the present invention, when defrosting is performed by switching the refrigerant circuit using the switching valve, refrigerant gas is sucked from the evaporator into the low-stage compressor and the high-stage compressor at the same time and compressed at the same time. This is what I did.

[Effect]

In the refrigerant circuit switching device of this invention, the suction circuit of the high-stage compressor during defrosting becomes the same as the suction circuit of the low-stage compressor, so that the evaporator pressure does not increase during defrosting. Even though
It is possible to prevent the suction pressure of the high-stage compressor from increasing.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Note that the same or equivalent parts as in FIG. 3 are indicated by the same reference numerals.

In FIG. 1, 14 is a four-way valve that is a switching valve for switching the refrigerant circuit, and 15 and 16 are check valves that prevent high-pressure gas and high-pressure discharge gas from flowing back to the lower stage side.

Next, the operation will be explained.

First, FIG. 1 shows the case of cooling,
By switching the west valve 14, a first refrigerant circuit is formed in which the refrigerant gas from the evaporator 9 is sequentially sucked into the low-stage compressor 1 and the high-stage compressor 2 and sequentially compressed.

Therefore, the high-pressure gas compressed by the low-stage compressor 1 and passed through the four-way valve 14 is cooled by the cooled refrigerant liquid through the low-stage gas cooling solenoid valve 5 and the cooling expansion valve 8. It is sucked into the stage side compressor 2.

The high-pressure gas compressed by the high-stage compressor 2 is liquefied in the condenser 4, passed through the electromagnetic valve 6, and further reduced in pressure by the expansion valve I, becoming a refrigerant that is easily evaporated. Next, this refrigerant is evaporated in the evaporator 9 and returned to the original refrigerant gas, and then sucked into the low-stage compressor 1 again.

Next, Figure 2 shows the case of defrosting,
By switching the four-way valve 14, a second refrigerant circuit is formed in which refrigerant gas from the evaporator 9 is sucked into the low-stage compressor 1 and the high-stage compressor 2 and compressed at the same time.

Therefore, the high-temperature, high-pressure gas compressed by the high-stage compressor 2 passes through the solenoid valve 1a and flows into the evaporator 9.
Release the charm attached to the. On the other hand, the high-temperature, high-pressure gas compressed by the low-stage compressor 1 also passes through the four-way valve 14, passes through the check valve 15 and the solenoid valve 10, and flows into the evaporator 9. Next, the refrigerant gas evaporated in the evaporator 9 is simultaneously sucked into the high-stage compressor 2 through the low-stage compressor 1, the check valve 16, and the four-way valve 14, and is simultaneously compressed.

During this defrosting, the suction circuit of the high-stage compressor 2 becomes the same as the suction circuit of the low-stage compressor 1, so the evaporator 9
Even if the pressure of the high-stage compressor 2 increases, the suction pressure of the high-stage compressor 2 does not increase, and overheating operation is prevented.

In the above embodiment, a four-way valve is used as the switching valve of the first and second cooling circuits, but any other switching valve may be used.

In addition, in the above embodiment, the case of defrosting was explained, but
The refrigerant circuit shown in FIG. 2 may be used during the high-temperature operation of the freezing operation, and the refrigerant circuit shown in FIG. 1 may be used during the low-temperature operation, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, even if the evaporator pressure increases during defrosting, the suction pressure of the high-stage compressor can be prevented from abnormally increasing by switching the refrigerant circuit. As a result, there is no need to install a suction pressure regulating valve or orifice to keep the suction pressure of the high-stage compressor constant, and the weight removal capacity can be sufficiently increased, resulting in high reliability and high performance. This has the effect of providing a refrigerator.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a refrigerator according to an embodiment of the present invention during cooling, FIG. 2 is a system diagram during defrosting, and FIG. 3 is a system diagram of a conventional refrigerator. 1 is a low stage compressor, 2 is a high stage compressor, 4 is a condenser, 9
is an evaporator, and 14 is a four-way valve that is a switching valve. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A low-stage compressor and a high-stage compressor that compress refrigerant gas into two stages, a condenser that liquefies the compressed high-pressure gas, and an evaporator that evaporates the liquefied refrigerant and returns it to the refrigerant gas. a first refrigerant circuit for sequentially sucking refrigerant gas from the evaporator into the lower-stage compressor and the higher-stage compressor and compressing the refrigerant gas sequentially; A refrigeration system characterized by comprising a second refrigerant circuit that causes a low-stage compressor and a high-stage compressor to draw in and compress the refrigerant at the same time, and a switching valve that switches between the first and second refrigerant circuits. Machine.