JPS62248968A - Refrigerator - 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 (a) Industrial Application Field The present invention comprises two independent refrigerant circuits, and a heat exchanger is formed between the evaporator of the high-temperature side refrigerant circuit and the condenser of the low-temperature side refrigerant circuit. The present invention relates to a so-called dual refrigeration type refrigeration system.

(b) Conventional technology Conventionally, this kind of so-called dual refrigeration type refrigeration equipment was developed, for example, in the
8-23101.

In other words, the high-temperature side and low-temperature side refrigerant circuits are configured with two independent refrigerant closed circuits, and the evaporator of the high-temperature side refrigerant circuit and the condenser of the low-temperature side refrigerant circuit constitute a heat exchanger. The refrigerant in the low temperature side refrigerant circuit is condensed by evaporation of the refrigerant in the refrigerant circuit. This makes it possible to use a refrigerant with a lower boiling point (evaporation temperature) in the low-temperature side refrigerant circuit, making it possible to obtain an extremely low temperature with the evaporator of the low-temperature side refrigerant circuit.

(c) Problems to be solved by the invention In such a dual refrigeration system, a low temperature of about -80°C is normally obtained in the evaporator of the low-temperature side refrigerant circuit, but it is possible to obtain a lower temperature of, for example, -130°C. In order to obtain the following temperatures, a refrigerant with an extremely low boiling point, such as R50 (methane), must be used in the low-temperature refrigerant circuit, which places a large load on the compressor of the low-temperature refrigerant circuit. Something happened,
There was a problem in that the temperature rose abnormally and caused seizure.

The present invention has been made to solve these problems.

(d) Means for solving the problems The present invention will be explained in detail with reference to embodiments. The evaporators (14A) (14B) of the high temperature side refrigerant circuit (2) constitute a cascade condenser (25A) (25B) together with the condensing pipes (23A) (23B) of the low temperature side refrigerant circuit (3). The low temperature side refrigerant circuit (3) includes a gas-liquid separator (29) (33), a plurality of intermediate heat exchangers (32) (42) (44), an electric compressor (10), an evaporation pipe (47), a plurality of Pressure reducer (
36), (40), and (46), etc., and is filled with a plurality of types of non-azeotropic mixed refrigerants with R50 as the final evaporative refrigerant to obtain an extremely low temperature of -150°C or the like in the evaporation pipe (47). The high temperature side refrigerant circuit (2) is filled with R502 refrigerant and R12 refrigerant for oil return, and the electric compressor (4) is charged from the accumulator (15).
) is connected to the oil cooler (11) of the electric compressor (10).

(E) Function According to the present invention, the refrigerant flows through the high temperature side refrigerant circuit (2) and the evaporator (1).
4A) Since the R12 refrigerant whose temperature has decreased in (14B) is evaporated in the oil cooler (11), the electric compressor (10) of the low temperature side refrigerant circuit (3), which has a very high temperature, can be cooled well.

(f) Example The invention will now be described in detail with reference to the drawings.

FIG. 1 shows a refrigerant circuit (1) of a refrigeration system (R) of the present invention. The refrigerant circuit (1) is composed of a high temperature side refrigerant circuit (2) as a first refrigerant closed circuit and a low temperature side refrigerant circuit (3) as a second refrigerant closed circuit, which are independent from each other. (4) is an electric compressor that uses a one-phase or three-phase AC power source that constitutes the high temperature side refrigerant circuit (2), and the discharge side piping (4D) of the electric compressor (4) is connected to the auxiliary condenser (5). The auxiliary condenser (5) is further connected to a sheath prevention vibe (6) that heats the opening edge of the freezer storage chamber, which will be detailed later, and then to the oil cooler (7) of the electric compressor (4). After being connected, it can be connected to the condenser (8). (9> is a blower for cooling the condenser (8). After the refrigerant pipe exits the condenser (8), it passes through the dryer (12). The first evaporator (as an evaporator part that constitutes the evaporator via the pressure reducer (13)
14A) and a second evaporator (14B), it is connected to an accelerator and a rake (15) as a refrigerant reservoir. The pipe coming out of the accumulator (15) connects to the oil cooler (11) of the electric compressor (10) that constitutes the low-temperature side refrigerant circuit (3).
After that, connect the suction side piping (4) of the electric compressor (4).
S). The first evaporator (14A) and the second evaporator (14B) are connected in series, and together constitute the evaporator of the high temperature side refrigerant circuit (2).

The high temperature side refrigerant circuit (2) is filled with refrigerants R502 and R12 (dichlorodifluoromethane) having different boiling points, and their composition is, for example, 88.0% by weight of R502 and 12% by weight of R12.
．． It is 0% by weight. The high-temperature gaseous refrigerant discharged from the electric compressor (4) is transferred to the auxiliary condenser (5) and the sheath prevention vibrator (
6), the oil cooler (7) and the condenser (8) are used to condense and liquefy heat, and then the moisture contained in the dryer (12) is removed, and the pressure is reduced in the pressure reducer (13). 2
Refrigerant R5 flows into the evaporator (14A) (14B) one after another.
02 is evaporated, the heat of vaporization is absorbed from the surroundings, and each evaporator (1
4A) (14B) and returns to the electric compressor (4) via the oil cooler (11) of the electric compressor (10) of the low temperature side refrigerant circuit (3) from the accumulator (15) as a refrigerant liquid reservoir. take action.

At this time, the capacity of the electric compressor (4) is, for example, 1.5 HP, and the final temperature reached by each evaporator (14A) (14B>) during operation is -50°C. R
12 has a boiling point of about -30°C, so each evaporator (14A
) (14B) does not evaporate and remains in a liquid state, so it hardly contributes to cooling, but it absorbs the lubricating oil of the electric compressor (4) and moisture that could not be absorbed by the dryer (12). The function is to return the melted state to the electric compressor (4). FIG. 9 shows a sectional view of the accumulator (15). Piping (15) connected to the evaporator (14B)
A) opens at the lower end inside the accumulator (15), and the pipe (15B) that can be connected to the oil cooler (11) is inserted into the accumulator (15) from three sides and bent at the lower end, and the open end is connected to the refrigerant liquid level. (H) It is facing upward.

An oil return hole (15C) is located at the lower end of this pipe (15B).
) is formed. In other words, R12 refrigerant flows through this hole (15C
) from the accumulator (15) and flows into the oil cooler (11) of the low-temperature side refrigerant circuit (3) in a liquid state containing the aforementioned lubricating oil and the like. Here, the temperature of the electric compressor (10) is determined by the oil cooler (11), which has a heavy load and high temperature in order to circulate a refrigerant with an extremely low boiling point such as R50 (methane), as described later. Since the R12 refrigerant that has flowed into the engine evaporates, it is cooled and seizure and lubricating oil deterioration are prevented. That is, the refrigerant R12 has the function of returning the lubricating oil in the high temperature side refrigerant circuit (2) to the electric compressor (4) and the function of cooling the electric compressor (10) of the low temperature side refrigerant circuit (3). Furthermore, since the liquid R12 refrigerant does not return to the electric compressor (4), damage to the valves, etc. of the electric compressor (4) will not occur.

A discharge side pipe (IOC) of the electric compressor (10) constituting the low temperature side refrigerant circuit (3) is connected to an auxiliary condenser (17) and then to an oil separator (18). Oil separator (18)
The oil return pipe (19) returns to the electric compressor (10) and the pipe connects to the dryer (20).
> is connected to the branching three-way pipe (21). Three-way tube (21
) One of the pipes coming out of the low-temperature side refrigerant circuit (3) is wound around the second suction side heat exchanger (22) for heat exchange and then inserted into the first evaporator (14A). It is connected to the first condensing vibe (23A) as a side pipe. Three-way tube (21
) is similarly wound around the first suction side heat exchanger (24) of the low temperature side refrigerant circuit (3) for heat exchange, and then inserted into the second evaporator (14B). It can be connected to the second condensing vibe (23B) as the high pressure side piping. The first evaporator (14A'), the first condensing pipe (23A) and the second
The evaporator (14B) and the second condensing vibe (23B) constitute cascade condensers (25A) and (25B), respectively. First and second condensing vibes (23A) (23
B> are connected by a collecting three-way pipe (27), and then put into a dryer (
28) to the first gas-liquid separator (29).

The gas phase piping (30) coming out of the gas-liquid separator (29) passes through the first intermediate heat exchanger (32) and enters the second gas-liquid separator (
33). The liquid phase pipe (34) coming out of the gas-liquid separator (29) passes through a dryer (35) and then a pressure reducer (36).
It is connected between the first intermediate heat exchanger (32) and the second intermediate heat exchanger (42) via the intermediate heat exchanger (32). The liquid phase pipe (38) coming out of the gas-liquid separator (33) passes through a dryer (39) arranged for heat exchange in a third intermediate heat exchanger (44), and then is transferred to a pressure reducer (4).
0) between the second intermediate heat exchanger (42) and the third intermediate heat exchanger (44). Gas-liquid separator (33)
The gas phase pipe (43) coming out from the second intermediate heat exchanger (42
), then passes through the third intermediate heat exchanger (44), and is depressurized through the dryer (45), which is also disposed in the third intermediate heat exchanger (44) for heat exchange. (46). The pressure reducer (46) is an evaporator vibrator (4) as an evaporator.
7>, and the evaporation pipe (47) is further connected to a third intermediate heat exchanger (44). Third intermediate heat exchanger (
44) is the second (42) and first intermediate heat exchanger (32)
), and then connected to an accumulator (49), which is further connected to a first suction side heat exchanger (24), and further connected to a second suction side heat exchanger (22). to the suction side piping (10) of the electric compressor (10).
5). The suction side pipe (tOS) is further provided with an expansion tank (5) that stores refrigerant when the electric compressor (10) is stopped.
1) is connected via a pressure reducer (52).

Four types of mixed refrigerants having different boiling points are sealed in the low temperature side refrigerant circuit (3). That is, R12 (dichlorodifluoromethane), R13B1 (promotrifluoromethane), R
A mixed refrigerant consisting of 14 (tetrafluoromethane) and R50 (methane) is sealed in a premixed state. The composition of each refrigerant is, for example, 4.0% by weight of R50 and 2% by weight of R14.
2.0% by weight, R13B1 is 39.0% by weight, and R12 is 35.0% by weight. R50 is methane, which causes an explosion when combined with oxygen, but the danger of explosion is eliminated by mixing it with each fluorocarbon refrigerant in the above proportions. Therefore, even if a mixed refrigerant leakage accident occurs, an explosion accident will not occur.

Here, in the embodiment, the evaporator of the high temperature side refrigerant circuit (2) is divided into two evaporator parts, namely a first and second evaporator (14A) (1/IB
), and connect the high pressure side piping of the low temperature side refrigerant circuit (3) to the first
By dividing into the second condensing pipe (23A) (23B), two cascade condensers (25A) (25B)
), but the present invention is not limited thereto, and the capacitor may be divided into even more cascade capacitors without departing from the spirit of the present invention.

Next, to explain the circulation of the refrigerant, the high temperature and high pressure gaseous mixed refrigerant discharged from the electric compressor (10) is transferred to the auxiliary condenser (10).
7), most of the lubricating oil mixed with the refrigerant in the electric compressor (10) is removed from the oil separator (18) through the oil return pipe (19) to the electric compressor (10). After passing through the dryer (20), the refrigerant itself is divided into two by a three-way pipe (21). The refrigerant divided into two by the three-way pipe (21) is precooled separately in the suction side heat exchanger (22) or (24), and then transferred to the first (14A) in the cascade condenser (25A) or (25B), respectively. ) or the second evaporator (14B) to condense and liquefy part of the refrigerant with a high boiling point in the mixed refrigerant, and then merge in the three-way pipe (27). At this time, the mixed refrigerant is divided into two parts and cooled in small amounts separately in the cascade condenser (25A) or (25B), so that sufficient heat exchange is carried out and the condensation effect is achieved satisfactorily.

The mixed refrigerant that has exited the three-way pipe (27) passes through the dryer (28) and flows into the gas-liquid separator (29). At this point, R14 and R50 in the mixed refrigerant have extremely low boiling points, so they are not condensed yet and are in a gaseous state. Only R12 and R13B1 have been condensed and liquefied, so R14 and R50 are connected to the gas phase piping (3
0), R12 and R13B1 are separated into liquid phase piping (34). The refrigerant mixture that has flowed into the gas phase pipe (30) is condensed by exchanging heat with the first intermediate heat exchanger (32), and then
This leads to a gas-liquid separator (33).

Here, the first intermediate heat exchanger (32) has an evaporating vibrator (4
7) The low-temperature refrigerant that returns from the pipe flows in, and the R13B1 that flows into the liquid phase pipe (34) passes through the dryer (35) and is depressurized in the pressure reducer (36), and then is transferred to the first intermediate heat exchanger. Since the first intermediate heat exchanger (32) contributes to cooling by flowing into the heat exchanger (32) and evaporating there, the temperature of the first intermediate heat exchanger (32) is -80℃.
It is about °C. Therefore, most of the R14 in the mixed refrigerant that has passed through the gas phase pipe (30) is condensed and liquefied, and the R50
has a lower boiling point, so it is still in a gaseous state. Therefore, R1
4 is from the gas-liquid separator (33) to the liquid phase pipe (38), and R
50 is separated into a gas-phase pipe (43), and R14 is depressurized by a pressure reducer (40) through a dryer (39) and then connected to a second intermediate heat exchanger (42) and a third intermediate heat exchanger ( 44) and evaporates in the second intermediate heat exchanger (42). The return low-temperature refrigerant from the evaporator vibe (47) flows into the second intermediate heat exchanger (42), and the evaporation of R14 further contributes to cooling, so the temperature of the second intermediate heat exchanger (42) is The temperature is about -100'C. Furthermore, since the return low-temperature refrigerant from the evaporator vibrator (47) immediately flows into the third intermediate heat exchanger (44), its temperature is -120°C.
Since the temperature is extremely low, the gas phase piping (which exchanged heat with the second and third intermediate heat exchangers (42) and (44))
The refrigerant R50 having the lowest boiling point passing through the refrigerant R50 (43) is condensed and liquefied, passed through the dryer (45) and reduced in pressure in the depressurizer (46), and then flows into the evaporation vibrator (47) where it is evaporated. At this time, the temperature of the evaporating vibrator (47) has reached -150°C. This is the final temperature reached by the refrigeration system (R) of the present invention, and by disposing this evaporating vibrator (47) in a storage compartment of a freezer described later in a heat exchange manner, storage compartment-1
2= It becomes possible to create an ultra-low temperature environment of -140°C inside. Refrigerant (mostly R) flowed out from the evaporator vibrator (47).
50) are the third, second, and first intermediate heat exchangers (
44) The refrigerant flows into and out of (42) and (32) one after another, and while merging with each refrigerant R14, R13B1, and R12, the unevaporated refrigerant is separated in the accumulator (49), and then the suction side heat exchanger (24) ( 22) one after another to be cooled, and then sucked into the electric compressor (10).

Here, the liquid phase piping (34) is connected to the first gas-liquid separator (29).
The R12 that has flowed into the first intermediate heat exchanger (32) flows into the first intermediate heat exchanger (32), but since it is already at an extremely low temperature, it does not evaporate and remains in a liquid state, so it does not contribute equally to cooling, but oil separation It functions to return residual lubricating oil that could not be separated in the dryer (18) and mixed water that could not be completely absorbed in the dryers to the electric compressor (10) in a dissolved state. When the lubricating oil of the electric compressor (10) circulates in the low-temperature side refrigerant circuit (13), the extremely low temperature causes the lubricating oil to remain in various parts, causing clogging.

Therefore, R12 achieves almost complete return of lubricating oil.

By repeating the above, the refrigerant circuit (1) operates to generate an extremely low temperature of -150"C in the evaporator vibrator (47) in a steady state, but the electric compressors (4) and (10) operate at 1.5H.
It only requires a P level ability, and does not require any particularly great ability.

This is largely due to the good heat exchange in the cascade condenser (25A) (25B) and the selection of the mixed refrigerant. This makes it possible to reduce the noise and power consumption of the electric compressor. Also, -150℃
By achieving this, it will be possible to cool the biological materials in the freezer to a temperature lower than the recrystallization point of ice, which will be described later, and permanent preservation will be achieved. Furthermore, the high temperature side refrigerant circuit (2)
The refrigerant is transferred from the first evaporator (14A) to the second evaporator (14B).
), and since it is not divided, both evaporators (14
A) Even if the temperature balance of (14B) collapses for some reason, a deviation in the refrigerant flow rate may occur. Therefore, the first condensing pipe (23A) and the second condensing pipe ( 23B> is achieved, and a good condensation effect is achieved.

Next, FIG. 2 schematically shows a control electric circuit for the refrigeration system (R) of the present invention. (4M) is a motor for driving the electric compressor (4>) of the high temperature side refrigerant circuit (2), and is connected between -phase or three-phase AC power supply (AC>(AC). That is, motor (4M) is a continuous operation while the power supply (AC) is turned on. (IOM) is a motor for driving the electric compressor (10) of the low temperature side refrigerant circuit (3),
A power supply (A) is connected in series with the contact (60A) of the electromagnetic relay (60).
C) Connected to (AC). The contact (60A) energizes the coil (60C) of the electromagnetic relay (60) and closes it, operating the motor (IOM). (A.C.
), it essentially detects the temperature inside the storage chamber, sets an appropriate differential above and below the set temperature, generates a voltage between the output terminals (61A) and (61B) at the upper limit temperature, and generates a voltage between the output terminals (61A) and (61B) at the lower limit temperature. Stop occurrence. This set temperature is -14
The temperature is 5°C to -150°C. Output terminal (61A) (61
The coil (62C) of the temperature control relay (62) and the contact (63A) of the timer (63) are connected in series between B). The temperature control relay (62) closes the contact (62A) by energizing the coil (62C). (65) is a high-pressure switch provided in the electric compressor (10) discharge side piping (IOD) of the low temperature side refrigerant circuit (3) in FIG. 1, upstream of the auxiliary condenser (17). The high voltage switch (65) is the power supply (AC)
(AC) is connected in series with the timer (63),
The pressure on the discharge side of the electric compressor (10) increases and the compressor (10)
0), for example 26 kg.
/cm' opens the contacts and closes them when the pressure drops to a sufficiently safe condition, for example 8 kg/cm'12. The timer (63) closes the contact (63A) after 3 to 5 minutes have passed after the contact of the high pressure switch (63) has closed.
The high voltage switch (65) opens and contacts (63A) open.

(66) is a low temperature start thermostat, which is installed to sense the temperature of the accumulator (15) of the high temperature refrigerant circuit (2). The refrigerant evaporated in each evaporator (14A) (14B) and the unevaporated refrigerant flow into the accumulator (15), so the temperature is almost the same as that of the evaporator (14A) (14B), but the temperature is lower. The starting thermostat (66) closes the contacts when the temperature of the accumulator (15) drops to, for example, -35°C, and opens the contacts when the temperature rises to -10°C. Low temperature start thermostat (6 (
i) The power supply (AC) is configured by forming a series circuit with the contact (62A) of the temperature control relay (62) and the timer (68) on both sides.
(AC). The common terminal of the changeover switch (69) of the timer (68) is connected between the timer (68) and the low temperature start thermostat (66), and the electromagnetic terminal is connected between the changeover switch (69) terminal (69A) and the power supply (AC). The coil (60C) of the relay (60) is connected, and the pressure reducer (46) shown in Figure 1 is connected between the terminal (69B) and the power supply (AC).
) Heaters (70) (71
) are connected in parallel. The timer (68) always closes the changeover switch (69) to the terminal (69A), and integrates electricity when it is energized. When this integration reaches, for example, 12 hours, it closes the switch (69) to the terminal (69B) for, for example, 15 minutes. and close the terminal (69A) again.

Next, the operation will be explained with reference to the timing chart of FIG. When the refrigeration system (R) is installed and the power (AC) is turned on at time (to), the motor (4M) starts, the electric compressor (4) operates, and the high temperature side refrigerant circuit (
2) Refrigerant begins to circulate inside. At this time, the accumulator (
15) is close to room temperature, the low temperature start thermostat (66) is open, and therefore the temperature regulator (66) is in an open state.
Regardless of 1), the coil (
60C) is not energized and therefore the contact (60A) is open, the motor (IOM) does not start and the electric compressor (10) of the low temperature side refrigerant circuit (3) does not operate. Cooling operation of only the high-temperature side refrigerant circuit (2>) continues,
As the liquid refrigerant accumulates in the first and second evaporators (14A) (14B), the temperature decreases, and the temperature of the accumulator (15) decreases at time (t,).
When the temperature reaches -35°C, the low temperature start thermostat (66)
closes the contact. Just before this closing operation, the electric compressor (10) is stopped, so naturally the high pressure switch (65) is stopped.
) is closed, and since 3 to 5 minutes have naturally passed since the power was turned on, the timer (63) has also closed its contact (63A). Furthermore, since the temperature in the storage chamber is naturally higher than the set temperature, the temperature regulator (61) is also generating an output, so the contact (62A) of the temperature control relay (62) is closed. Therefore, when the cold start thermostat (66) closes, the coil (60C> of the electromagnetic relay (60) is energized and the contact (
60A> is closed, the motor (IOM) is started, and the mixed refrigerant is discharged from the electric compressor (10) and begins to be circulated within the circuit (3).

At this time, the temperature of each part of the low-temperature side refrigerant circuit (3) is still high, and since most of the refrigerant inside is in a gaseous state, the pressure inside the circuit is high. Moreover, since the refrigerant is pushed out from the electric compressor (10), the pressure in the discharge side pipe (10D) increases rapidly. If this is left unchecked, the components of the electric compressor (10) will be damaged by the high pressure, but the peak value of this pressure rise is 26 kg/a, which is the permissible limit at time (t2).
m'', the high voltage switch (65) senses it and opens the contact, which opens the contact (63A), which forces the contact (62A) of the temperature control relay (62) to open, and the coil ( 60C) becomes de-energized and the contact (60A)
opens and the motor (101'l) stops. This prevents pressure from rising on the discharge side of the electric compressor (lO) and prevents damage.

By stopping the electric compressor (10), the discharge side piping (10D
The pressure of the motor (IOM ) does not start.

During this time, the pressure in the low temperature side refrigerant circuit (3) changes from the first or second evaporator (14A) (14B) to the first or second evaporator (14A) (14B).
Since the refrigerant cooled in the condensers (23A) (23B> is circulated to some extent and evaporated, the temperature and pressure have decreased since the last startup.The timer (63)
) When the delay time due to ) has elapsed at time (t, ), the contact (63A> is closed again and the motor (IOM)
is started, but the pressure in the discharge side piping (IOD) is 26k
When g reaches H, the high voltage switch (65) is opened again and the motor (10) is stopped. A motor like this (
As the IOM) is repeatedly started and stopped, the refrigerant with a high boiling point evaporates and gradually exerts a cooling effect, so that the temperature gradually decreases from the first intermediate heat exchanger (32). , Discharge side piping (IOD) when starting the motor (IOM)
When the peak value of the pressure increase no longer reaches 26 kg/cm'', the motor (IOM) enters continuous operation.

By continuously operating the electric compressor (10), the refrigerant with a low boiling point is also condensed and gradually begins to exert a cooling effect.
The temperatures of each intermediate heat exchanger (32) (42) (44) and the evaporating vibe (47) are gradually lowered to reach the final temperature mentioned above. After that, the temperature in the storage room is adjusted by the temperature controller (61)
When the lower limit temperature set in is reached, the output terminal (61A) <6
1B), the contact (62A) opens, and the contact (60A) also opens, so the motor (10M
) will stop, and cooling operation will stop. After that, the temperature inside the storage room gradually rises and when it reaches the upper limit temperature set by the temperature controller (61), the contact (62A> closes again, and the contact (60A>) closes again to start the motor (IOM) and restart it. Cooling operation is started. By repeating the above steps, the storage chamber is maintained at the set temperature, for example, -140° C. on average.

Here, the timer (68) integrates the time that the contact (62A>) and the cold start thermostat (66) are closed, that is, the time that the motor (IOM) is operating, and when this integration reaches 12 hours, the switch is switched. Since the switch (69) is closed to the terminal (69B), the operation of the motor (10M) is prohibited, and the heaters (70) and (71) are energized and generate heat.Here, the third intermediate heat exchanger (44) is turned off. The R50 flowing into the pressure reducer (46) has reached an extremely low temperature of -120"C or less. Therefore, there is an extremely small amount of moisture in this refrigerant (this enters during refrigerant replenishment work, etc.). If it is mixed in, ice will form in the pipes.By the way, pressure reducers are usually constructed of small diameter pipes, so if ice grows in this pressure reducer (46), it will clog and the refrigerant will drain. However, in the present invention, since the pressure reducer (46) is periodically heated by the heaters (70) (71), the ice crystals are melted and do not grow, thus preventing such an accident. This heater (70) (71
) ends in 15 minutes, the switch (69) is closed again to the terminal (69A), the motor (IOM) is activated, and the cooling operation of the low temperature side refrigerant circuit (3) is started as described above.

Next, FIG. 4 shows a front perspective view of a freezer (75) to which the present invention is applied, and FIG. 5 shows a sectional view of a main part thereof. Furthermore, the sixth
The figure is a diagram illustrating a specific configuration of a refrigerant circuit (1) of a refrigeration system (R). The freezer (75) is installed in physical and chemical laboratories, etc., and (74) is the storage room (74) with an upward opening.
6), the upper opening of which is openably closed by a heat insulating door (77) rotatably supported on the rear side. A machine room (78) is formed on the side of the main body (74) to house and install a temperature controller (61), electric compressors (4), (10), etc., and in front of it is a machine room (78) that accommodates the temperature controller (61), electric compressors (4), (10), etc. A self-recording temperature recorder (79) that senses the temperature of the room and records its change over time on recording paper, a common knowledge alarm (80) that issues an alarm in case of abnormally high temperature in the storage room (76), and a temperature controller (61). A setting change knob (81) is provided.

Further, (82) is a ventilation slit.

FIG. 5 shows a cross-sectional view of the main body (74). (
83) is a steel plate outer box with an upward opening, (84) is an aluminum inner box with an upward opening, and the inner box (84> is built into the outer box (83), ) Box-shaped external insulation material (85) with independent upward openings between each
A double heat insulating layer consisting of the inner heat insulating material (86) and the inner heat insulating material (86) has been formed, and the opening edges of both boxes (83) and (84) are connected with the breaker (87). An evaporation pipe (
47) is disposed in a thermally conductive manner and buried in the inner insulation material (86), and a sheath prevention pipe (6) is disposed in a thermally conductive manner on the inner surface of the opening edge of the outer box (76). It is set up. The inner insulation material (86) is placed inside the outer insulation material (85) and is completely separated, so even if the inner insulation material (86) contracts due to the cooling action of the evaporation pipe (47), External insulation material (8
5) is not affected to the same extent, therefore, cracking of the heat insulating material does not occur, and sufficient heat insulating performance is maintained. An opening (88) is formed on the back surface of the outer box (83), and a corresponding notch (89) is formed in the outer heat insulating material (85). 88), cascade capacitors (25A) (25B) etc. molded with a heat insulating material (90) as described later are housed and covered with a cover plate (91). (92) is an inner cover made of polystyrene foam, (93) is a gasket on the inner peripheral surface of the heat insulating door (77), and <94) is a caster for transportation.

Next, FIG. 6 shows a specific configuration of the refrigerant circuit (1) of the refrigeration system (R), in which the same reference numerals as in FIG. 1 are the same. The auxiliary condenser (17) of the low temperature side refrigerant circuit (3) is connected to the high temperature side refrigerant circuit (2) with respect to the air suction type blower (9).
) is placed on the windward side of the condenser (8) so that it is cooled at the same time. First and second evaporators (14A) (14
B) has the shape of a hollow tank, into which first and second condensation pipes (23A) and (23B) wound in a spiral manner are respectively inserted from above. (6
6A) is a cylindrical body for fixing a low temperature starting thermostat (66) that is welded and fixed to the accumulator (15). (9
6) is each intermediate heat exchanger (32) (42) (44) described later.
), etc., and is molded with a heat insulating material (97) to form a box-like intermediate heat exchanger section. The evaporation pipe (47) is fixed in advance to the outer surface of the inner box (84) in a meandering manner with aluminum tape or adhesive, but in order to reduce the temperature distribution in each part of the storage chamber (76), it is necessary to The order in which the refrigerant flows is from around the top of the inner box (84) to around the bottom, and finally around the bottom.

FIG. 7 shows the structure of the intermediate heat exchanger section (96). The parts surrounded by dotted lines are the first, second and third intermediate heat exchangers (32)
<42) (44), a second gas-liquid separator (33), a dryer (39) (45), a pressure reducer (40) and an accumulator (49), which is an intermediate heat exchanger section (96). . Each of the intermediate heat exchangers (32), (42), and (44) is formed by winding relatively large-diameter outer pipes (9g), (99), and (100) in multiple stages in a spiral shape to make them flat, which are then mutually polymerized. It has a spiral double pipe structure in which the gas phase pipes (30) and (43) pass through the inner pipe at intervals, and the part (A) in the figure is the first intermediate heat exchanger. The part (B) serves as the second intermediate heat exchanger (42), and the part (C) serves as the third intermediate heat exchanger (44). Inside this spiral, a second gas-liquid separator (33), a dryer (39) (45),
A pressure reducer (40) and an accumulator (49) are housed to reduce dead space and reduce size.

Next, the configuration will be explained. (101) is a pipe connecting the dryer (28) and the first gas-liquid separator (29). The gas phase pipe (30) exiting upward from the first gas-liquid separator (29) enters the outer pipe (98) through the sealed inlet (INI), passes around the inside in a spiral shape, and then passes through the outer pipe (98). Exit (OUTt
) and enters the second gas-liquid separator (33). The gaseous refrigerant flowing down in the gas phase pipe (30) is condensed by the low temperature refrigerant rising in the gap between the gas phase pipe (30) and the outer pipe (98) during this passage. The gas phase pipe (43) coming out of the second gas-liquid separator (33) enters the outer pipe (99) from the inlet (IN2). The liquid refrigerant separated in the first gas-liquid separator (29) is depressurized by the pressure reducer (36), and then the outlet (OUTt) of the outer pipe (98) and the inlet (99)
The gaseous refrigerant in the gas phase pipe (30) is condensed together with the refrigerant that flows into the communication pipe (102) connecting the IN2), evaporates in the outer pipe (98), and returns from the evaporation pipe (47). Contribute to The gas phase pipe (43) that entered the outer pipe (99) exits from the outlet (OUTt) and returns to the inlet (I).
It enters the outer pipe (100) from the outside pipe (100), circulates in a spiral shape, and exits from the outlet (OUT, ). The outer piping of each outlet and inlet section is sealed. Second gas-liquid separator (33
) The liquid refrigerant separated by the outer pipe (100) passes through a dryer (39) provided for heat exchange, is depressurized by a pressure reducer (40), and then is transferred to the outlet (OUTt) of the outer pipe (99). The refrigerant flows into the connecting pipe (103) connecting the inlet (IN,) of (100), evaporates in the outer pipe (99), and returns from the evaporator vibrator (47) together with the gas phase pipe (4).
3) Contributes to the condensation of the gaseous refrigerant within. Gas phase piping (43
) The refrigerant R50 flowing down inside the outside pipe (100) is further condensed and almost liquefied as it passes through the outside pipe (100).
It reaches the pressure reducer (46>) through the dryer (45) installed for heat exchange with the outside pipe (100). O
UT8) and communicates with the outer space of the gas phase pipe (43). In addition, (106) is the inlet (
This is a pipe that communicates between the outer space of the gas phase pipe (30) and the accumulator (49) in the INI). That is, the return refrigerant from the evaporation pipe (47) flows from the pipe (105) into the space between the outer pipe (100) and the gas phase pipe (43), rises there, and flows down inside the gas phase pipe (43). The incoming refrigerant is condensed, merged with the refrigerant from the pressure reducer (40) in the communication pipe (103), and transferred to the outer pipe (99) and the gas phase pipe (43).
) and rise there, and the gas phase pipe (43)
The refrigerant inside is condensed, and then the communication pipe (102) is connected to a pressure reducer (
36), flows into the gap between the outer pipe (98) and the gas phase pipe (30), rises there, condenses the refrigerant in the gas phase pipe (30), and then flows into the pipe (36). 106) to the accumulator (49), and the pipe (108)
It flows into the suction side heat exchanger (24). As described above, the flow of refrigerant flowing down inside the gas phase pipe (30) or (43) and the flow of refrigerant flowing down inside the gas phase pipe (30) or (43) and the flow from the evaporation pipe (47) to the gas phase pipe (30) or (
43) and the flow of refrigerant rising between the outer pipes (100), (99), and (98) are mutually opposing flows.

Next, FIG. 8 shows a rear perspective view of the freezer (75), and the procedure for assembling the refrigeration apparatus (R) will be explained. An opening (110) is formed on the back side of the outer box (83) in parallel with the opening (88), and correspondingly, a notch (111) is also formed in the outer insulation material (85).
) is formed. In the heat insulating material (90), the cascade condensers (25A) (25B), suction side heat exchangers (22) (24), accumulator (15), and dryer (28) are molded. The molding method for the insulation materials (90) and (97) is to house the parts to be molded in a resin bag, place them in a box-shaped foam mold in that state, and fill the bag with foam and mold the urethane insulation material. It is something to do. A pressure reducer (46) and piping (105) are extended from the insulation material (97),
The notch (111) is connected by welding to the evaporating vibrator (47) led out from the lead-out part (112) (112) at the back.

Pipes such as the pressure reducer (13) extending from the heat insulating material (90) are welded and connected to piping led out from the wall surface of the notch (89) on the machine room (78) side. The first gas-liquid separator (29) and the dryer (35) are located outside the heat insulating material (90), and the insulating materials (90) and (97) are also connected to each other with piping, and the notches (89) (111) ) and fill the gap with glass wool, etc., then use the cover plate (91) to connect the notch (89) and (
111) to complete the installation. In addition, electric compressors (4) (10), condenser (8), blower (9), expansion tank (51), etc. are installed in advance in the machine room (78), so that the freezer (75) Complete.

(G) Effects of the Invention According to the present invention, the liquid oil return refrigerant whose temperature has decreased in the evaporator of the high temperature side refrigerant circuit is evaporated in the lubricating oil cooler of the electric compressor of the low temperature side refrigerant circuit. It is possible to properly cool the electric compressor in the low-temperature side refrigerant circuit, which gets hot, to prevent seizure and deterioration of the lubricating oil, and also to prevent damage caused by liquid return to the electric compressor in the high-temperature side refrigerant circuit. be effective.

[Brief explanation of drawings]

Each figure shows an embodiment of the present invention, and FIG. 1 is a refrigerant circuit diagram of the refrigeration system, FIG. 2 is an electric circuit diagram for controlling the same, FIG. 3 is a timing chart explaining the operation of the refrigeration system, and FIG. 4 5 is a side sectional view of the freezer body, FIG. 6 is a diagram showing the specific configuration of the refrigerant circuit of the refrigeration system, FIG. 7 is a perspective view of the intermediate heat exchanger section, and FIG. 8 is a perspective view of the freezer. is a rear perspective view of the freezer,
FIG. 9 is a sectional view of the accumulator of the high temperature side refrigerant circuit. (R)... Refrigeration device, (2)... High temperature side refrigerant circuit, (3)... Low temperature side refrigerant circuit, (4) (10)...
・Electric compressor, (11)...Oil cooler, (1
4A) (14B)... Evaporator, (15)... Accumulator, (23A) (23B)... Condensing vibe,
(25A) (25B)...Cascade capacitor. Applicant Sanyo Electric Co., Ltd. and one other agent Patent attorney Takuji Nishino and one other person Figure 8 Figure 9

Claims (1)

[Claims] 1. Consisting of a high-temperature side refrigerant circuit and a low-temperature side refrigerant circuit, each of which constitutes an independent refrigerant closed circuit that condenses and then evaporates the refrigerant discharged from the compressor to exert a cooling effect, and the evaporation of the high-temperature side refrigerant circuit In a refrigeration system in which a heat exchanger is constituted by a condenser and a condenser in the low temperature side refrigerant circuit, the refrigerant with a low boiling point that exerts a cooling effect and lubricating oil for the compressor are returned to the high temperature side refrigerant circuit. A lubricating oil cooler for the compressor of the low temperature side refrigerant circuit is configured by a part of the piping which is filled with a refrigerant having a relatively high boiling point and returns to the compressor of the high temperature side refrigerant circuit via the heat exchanger. Refrigeration equipment.