JPH027411Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention uses two mutually independent refrigeration cycles, one of which is the high-temperature side refrigeration cycle.
The evaporator of one refrigeration cycle and the condenser of the other refrigeration cycle (low-temperature side refrigeration cycle) are thermally coupled to form a cascade condenser, and the compressors of the two refrigeration cycles are operated to maintain the ultra-low temperature inside the refrigerator. This relates to a dual refrigeration system.

[Conventional technology]

Conventionally, in a binary refrigeration system, the compressor, condenser, and evaporator are connected in sequence for both the high-temperature side and low-temperature side refrigeration cycles, and the evaporator of the high-temperature side refrigeration cycle and the condenser of the low-temperature side refrigeration cycle are connected thermally. It was known that a cascade capacitor was constructed by combining the Then, the condenser of the low-temperature side refrigeration cycle is cooled by the evaporator of the high-temperature side refrigeration cycle, and the inside of the refrigerator is brought to an ultra-low temperature state by the evaporator of the low-temperature side refrigeration cycle via the low-temperature refrigerant used in the low-temperature side cooling cycle. It was cooling down. In addition, the general method for starting up such a dual refrigeration system is to first operate the high-temperature side compressor to sufficiently cool the cascade condenser, and then operate the low-temperature side compressor to cool the inside of the refrigerator. It was hot.

[The problem that the idea aims to solve]

In the above-mentioned dual refrigeration system, the inside of the refrigerator is cooled from room temperature to ultra-low temperature after the low-temperature side compressor starts operating, so it takes time from the initial startup to cool down the inside of the refrigerator, and The side compressor was also under strain.

In addition, when maintaining the internal temperature at a relatively high level (-30°C or higher), the cooling capacity becomes redundant and the low-temperature side compressor repeatedly starts and stops, resulting in a short cycle and oil leakage. This causes wear and tear on various parts of the electric motor in the low-temperature side compressor and burnout of the windings.

Furthermore, if the low temperature side refrigeration cycle stops,
The interior of the refrigerator is no longer cooled at all.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a high-temperature side refrigeration cycle that includes a high-temperature side compressor, a high-temperature side condenser, a second high-temperature side evaporator for cooling the inside of the refrigerator, and a first cascade condenser. The high-temperature side evaporator is connected in sequence, and the outlet side of the high-temperature side condenser and the inlet side of the first high-temperature side evaporator are connected by a bypass pipe provided with refrigerant switching means. The refrigeration cycle uses a low-temperature side compressor,
The cascade condenser consists of a low-temperature side condenser, a low-temperature side evaporator for cooling the inside of the refrigerator, and a low-temperature side compressor for initial startup and when keeping the inside of the refrigerator at a relatively high temperature. At the same time, the refrigerant switching means supplies refrigerant from the high-temperature side refrigeration cycle to the second high-temperature side evaporator, and when keeping the inside of the refrigerator in an ultra-low temperature state, both the high-temperature side and low-temperature side compressors are operated. Along with letting
This is a dual refrigeration system having a control means that uses a refrigerant switching means to supply the refrigerant of the high temperature side refrigeration cycle only to the first evaporator through a bypass pipe.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIG. 1 (cooling circuit) and FIG. 2 (electric circuit).

In Figure 2, the cold storage temperature switch
The high-temperature side thermostat Th ₁ , which sets the SW to the 1 side, is a contact type that detects the temperature inside the refrigerator and switches the contact.When the temperature has cooled to a certain set temperature, it switches to the B contact side, and when the temperature rises to a certain set temperature, it switches to the B contact side. Switches to the a contact side. During initial operation, the high-temperature side thermostat _Th1 is connected to the a contact side, the coil of the relay _R1 is energized, the high-temperature side compressor comp _H starts operating, and the high-temperature side compressor comp H starts operating. The valve is also energized and the flow path inside the three-way valve becomes →. The refrigeration cycle at this time is as follows from Figure 1.

comp _H (high temperature side compressor) → cond _H (high temperature side condenser)
→ Receiver → Dryer → Three-way valve (→) →
Capillary reach tube C _H1 → eva _H ′ (second high temperature side evaporator) → check valve → eva _H (cascade condenser, first high temperature side evaporator) → low pressure receiver →
The comp _H second high temperature side evaporator eva _H ' is a cooling pipe wrapped around a heat insulating box, and cools the inside of the refrigerator in the above-mentioned refrigeration cycle. At the same time, the cascade condenser is cooled through the first hot side evaporator eva _H. Next, when the temperature inside the refrigerator is cooled to the temperature set by the high temperature side thermostat _Th1 , the high temperature side thermostat _Th1 is connected to the b contact side as shown in FIG. At this time, the coil of relay _R2 is energized, and the low-temperature side compressor comp _L and the high-temperature side compressor
Both comp _H units are in operation, and at the same time the three-way valve
When the SV is de-energized, the flow path inside the three-way valve is →
From →, a binary refrigeration cycle shown in FIG. 1 is constructed. That is, high temperature side refrigeration cycle comp _H → cond _H → receiver → dryer → three-way valve (→) → bypass pipe → capillary reach tube C _H2 → eva _H (cascade condenser, first high temperature evaporator) → low pressure receiver → comp _H Low temperature side refrigeration cycle comp _L (low temperature side compressor) → Oil separator →
cond _L (cascade condenser, low temperature side condenser)
→ Dryer → Capillary reach tube C _L1 →eva _L
(Low temperature side evaporator)→comp _LIn the high temperature side refrigeration cycle, refrigerant is supplied only to the first high temperature evaporator as described above, and refrigerant supply to the second high temperature evaporator is stopped.

At this time, the first high-temperature evaporator EVA _H cools the cascade condenser section and the inside of the refrigerator in advance, so the load on the low-pressure side compressor is extremely reduced, making it possible to easily survive the initial startup. Become. In addition, the inside of the refrigerator has been cooled by switching to the low-temperature side evaporator EVA _L , which causes the temperature inside the refrigerator to drop rapidly compared to the previous model. Here, the first high temperature side evaporator EVA _H and the low temperature side condenser cond _L form a cascade condenser, and the low temperature side evaporator EVA _L is connected to the second high temperature side evaporator cond L.
eva _H ′ is a cooling pipe wrapped in parallel and independently in an insulated box. Second high temperature side evaporator
While eva _H ' is cooled by the hot side refrigerant during initial start-up and during the single stage cycle, the cold side evaporator eva _L is cooled by the cold side refrigerant during the dual refrigeration cycle.

The check valve is for preventing the refrigerant circulating in the circuit from going around to the second high temperature side evaporator eva _H ' in the high temperature side refrigeration cycle of the binary refrigeration cycle. Necessary to ensure the amount of circulation. In the low-temperature side refrigeration cycle, the oil separator is branched and disposed between the low-temperature side compressor comp _L and the low-temperature side evaporator eva _L via an oil return adjustment capillary reach tube C _L2 .

At extremely low temperatures, the cold storage temperature switch SW is set to the 1 side,
The high temperature side thermostat _Th1 is on the b side, and the low temperature side thermostat _Th2 controls the temperature between -30 and -80℃, but when freezing to a relatively high temperature (-30℃ or higher) , From Figure 2, set the cold storage temperature switch SW to the 2 side. This will cause the relay
The coil _R3 is energized, the low temperature side compressor comp _L is stopped, and the high temperature side compressor comp _H is operated and stopped by the operation of the high temperature side thermostat _Th1 . In addition, the three-way valve is energized, and the flow path inside the three-way valve changes from → to → as shown in Figure 1, which is similar to the high temperature side refrigeration cycle at the initial startup of the binary refrigeration cycle.
A single-stage refrigeration cycle is formed to perform cooling. Note that the operating temperatures of the high-temperature side thermostat _Th1 and the low-temperature side _Th2 should not overlap.

[Effect of idea]

As described above, the present invention operates only the high-temperature side compressor at the initial startup, and the second high-temperature side evaporator cools the inside of the refrigerator in advance, so the low-temperature side compressor is operated and the low-temperature side compressor is operated. When the evaporator cools the inside of the refrigerator to an ultra-low temperature state, no load is placed on the low-temperature side compressor, and the cooling time is shortened.

Also, when cooling the inside of the refrigerator at a relatively high temperature (-30℃ or higher), only the high-temperature side compressor is operated, and the second high-temperature side evaporator is used to cool the inside of the refrigerator, as in the case of initial startup. As a result, unlike conventional dual refrigeration equipment, the low-temperature side compressor repeatedly starts and stops, resulting in a short cycle, which causes oil spillage, wear of various parts of the motor in the low-temperature side compressor, and burnout of the windings. There is no.

Furthermore, since single-stage refrigeration is possible using only the high-temperature side refrigeration cycle, even if the low-temperature side refrigeration cycle fails, cooling inside the refrigerator will not become impossible at all.

[Brief explanation of the drawing]

FIG. 1 shows a cooling circuit according to the invention, and FIG. 2 shows its electrical circuit. In the figure, comp _H ...high temperature side compressor, comp _L
...low temperature side compressor, cond _H ...high temperature side Finch-Eube condenser, cond _L ...low temperature side condenser, C _H1 ,
C _H2 , C _L1 , C _L2 ... Capillary reach tube, eva _H ,
eva _H ′...High temperature side evaporator, eva _L ...Low temperature side evaporator,
CM _H ...High temperature side compressor, CM _L ...Low temperature side compressor,
CF _H ...High temperature side fan motor, SV...Three-way valve,
Th ₁ ...High temperature side thermostat, Th ₂ ...Low temperature side thermostat, SW...Cool temperature selection switch (manual switch), R ₁ , R ₂ , R ₃ ...Relay coil section, R ₁ a, R ₂ a, R ₃ a……Relay contact, R ₂ b,
R ₃ b……Relay contact.

Claims (1)

[Scope of utility model registration request] In a binary refrigeration system in which the evaporator of the high-temperature side refrigeration cycle and the condenser of the low-temperature side refrigeration cycle constitute a cascade condenser, the high-temperature side refrigeration cycle cools the high-temperature side compressor, the high-temperature side condenser, and the inside of the refrigerator. A second high-temperature side evaporator for forming the cascade condenser and a first evaporator for forming the cascade condenser are sequentially connected, and the outlet side of the high-temperature side condenser and the inlet side of the first evaporator are connected in sequence. They are connected by a bypass pipe provided with a refrigerant switching means, and the low-temperature side refrigeration cycle is sequentially connected to a low-temperature side compressor, a low-temperature side condenser forming the cascade condenser, and a low-temperature side evaporator for cooling the inside of the refrigerator. Furthermore, at the time of initial startup and when keeping the interior of the refrigerator at a relatively high temperature, only the high-temperature side compressor is operated, and the refrigerant is supplied to the second high-temperature side evaporator by the switching means. When keeping the temperature at an ultra-low temperature, the high temperature side
A binary refrigeration system comprising control means for operating both low-temperature side compressors and for causing the switching means to supply refrigerant only to the first high-temperature side evaporator through the bypass pipe.