JPS6050351A - 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 The present invention relates to a refrigeration system, more specifically, a refrigeration system equipped with a hot gas bypass path, which guides hot gas to an evaporator to lower the internal temperature of a container or refrigerator, for example, to below -5°C to -6°C. The present invention relates to a refrigeration system that can control the temperature from a frozen region to a chilled region at a temperature higher than -5°C to -6°C.

Conventionally, a hot gas bypass path is provided in which hot gas discharged from a compressor bypasses a condenser and bypasses the evaporator, and the capacity is adjusted by controlling the amount of hot gas bypassed to the evaporator. For example, U.S. Pat.
No. 92,100 has already been proposed as shown in the specification and drawings.

The outline of this conventional device will be explained based on the schematic diagram shown in FIG. 8.
), the high pressure gas pipe (B,) connecting the inlet side of (C,)
), a hot gas bypass path (H
), and this hot gas bypass path (H) is connected to the inlet side of the evaporator (E), and the hot gas is connected near the connection part of the Ibus path (H) to the high pressure gas pipe (B). is provided with a hot gas valve (HV) for controlling the hot gas bypass amount to the evaporator (E).
By controlling the HV), the capacity of the evaporator (E) is adjusted to control the Suita air temperature and, by extension, the temperature inside the refrigerator to a chilled region.

By the way, in this conventional device, the evaporator (E) is
In the event of a stall, the hot gas valve (HV) allows the entire amount of circulating refrigerant to be circulated to the evaporator (E) to perform a defrost zero strike operation, but as described above, the hot gas can be bypassed. In refrigeration operation where the Suita air temperature is controlled in the chilled region, the low pressure of the refrigerant increases in accordance with the discharge air temperature, and the amount of refrigerant circulated increases accordingly. In the refrigeration operation where the refrigerant is controlled in the refrigeration region, the low pressure of the refrigerant is low and the amount of refrigerant circulated is also reduced, so when the defrost command is issued and the above-mentioned defrost operation using hot gas is performed, the amount of refrigerant circulating in the defrost circuit is , will change depending on the operating condition immediately before starting the defrost operation, resulting in problems such as those described above.

In other words, in a refrigeration operation where the Suita air temperature is controlled at a high temperature, when defrost operation is performed with the low pressure of the refrigerant becoming high and the amount of refrigerant circulating increasing, the amount of refrigerant flowing into the defrost circuit also increases. Because the number increases, the differential becomes zero in a short time.
On the other hand, the air temperature around the evaporator (E) at the end of the defrost stroke will be high, so when refrigerating operation is resumed, the refrigerant will enter an abnormal Shimada state and the compressor (E) will be damaged.
An overcurrent will flow through the motor in A), which will cause the high voltage switch and overcurrent relay to operate beyond the operating range, causing the problem that the motor cannot operate. When performing defrost operation when the low pressure of the refrigerant is low and the amount of refrigerant circulating is small, the amount of refrigerant flowing into the defrost circuit will also decrease, so the amount of defrost heat will be small and the defrost time will be longer. A problem arises.

In this way, when performing defrost operation by circulating hot gas to the evaporator (E), the amount of hot gas circulating to the evaporator (E) is As a result, proper defrost operation could not be performed depending on the operating conditions and the outside temperature at that time.

An object of the present invention is to set the amount of refrigerant circulated through the defrost circuit during defrost operation to the optimum amount that enables proper defrost operation, and to maintain the optimal defrost at normal pressure regardless of the operating state immediately before shifting to defrost operation. The point is to make it possible to perform zero strikes.

The configuration of the present invention includes a hot gas bypass path that bypasses the condenser and bypasses the hot gas discharged from the compressor to the evaporator, and controls the amount of hot gas bypass from the bypass path to the evaporator. In addition to controlling the capacity by
In a refrigeration system equipped with a hot gas valve that is fully opened to perform defrost operation at zero stroke, an on-off valve is provided on the downstream side of the condenser and closes when a command to start defrost operation is given. While the refrigerant is confined in a liquid reservoir including a condenser, a metering tank is provided to store the optimum amount of refrigerant required for defrost, and this tank is connected to the discharge side of the compressor, and defrost is performed by a defrost command. When operating, a constant amount of refrigerant preset in the metering tank is always circulated through the defrost circuit, regardless of the operating state immediately before, so that optimal defrost can be performed.

Next, an embodiment of the present invention will be described based on FIG.

What is shown in Fig. 1 is a container refrigeration system, in which (1) is a pressure #8 machine, (2) is an air-cooled condenser,
(8) is a water-cooled llI condenser, (4), #'i evaporator, (5
) is a temperature-sensitive expansion valve having a temperature-sensing part (51), and each of these devices is connected to a refrigerant pipe (6), and a refrigeration cycle for cooling the air inside the refrigerator is connected to the evaporator (4). is formed.

In the IfG1 diagram, (7) is a liquid receiver with an integrated accumulator, (7a) is a liquid receiving part, (7b) is an accumulator part, (8) is a dryer, and (9) is a liquid indicator. , (10) f'i is a fan attached to the evaporator (4), and (11) is a fan attached to the air-cooled condenser (2).

In the refrigeration cycle configured as above, the high pressure gas pipe (6a) K connecting the discharge side of the compressor (1) and the inlet side of the air-cooled condenser (2) is connected to the high pressure gas pipe (6a) K from the pressure m machine (1). The discharged hot gas is controlled by each of the above W! Compressor (2), (8
), the liquid receiving part (7a) of the liquid receiver (7), and the temperature-sensitive expansion valve (5
) is connected to a hot gas bypass path (20) that leads to the evaporator (4), and its outlet side is connected to the expansion valve (5).
) and the evaporator (4), connect to the low pressure liquid pipe (6b),
A hot gas valve (21) is installed at the connection site of the hot gas bypass path (2°) to the high pressure gas pipe (6a).
At the same time, on the downstream side of the condenser (8), downstream of the liquid indicator (9) in FIG. A valve (80) is provided to enable bombardment operation and to confine the refrigerant in a liquid reservoir including the condensers (2), (8) and the liquid receiving part (7a) of the liquid receiver (7). be.

Furthermore, there is a defrost circuit that performs defrost operation, that is, a compressor (1) and a hot gas valve (21).

Hot gas bypass path (20), X generator C4).

A metering tank (40) is provided in order to flow out a constant amount of refrigerant under the pressure of the defrost circuit that constitutes the accumulator section (rb>yb-) of the liquid receiver (7), and the tank (4o) is connected to the compressor (1).
) is connected to the discharge side of the

Specifically, the metering tank (4o) is connected to the suction gas pipe (6e).
), (low pressure gas pipe (6d), low pressure liquid pipe (6b)
), the refrigerant is attached to the metering tank (4o) so that heat exchange is performed between the high-pressure refrigerant stored in the metering tank (4o) and the low-pressure refrigerant flowing through the suction gas pipe (6e). Further, the metering tank (40) is connected to a portion of the high pressure gas pipe (6a) between the compressor (1) and the hot gas valve (21).

Thus, during normal operation, a portion of the high-pressure gas refrigerant discharged from the compressor (1) flows into the metering tank (40), and the tank (40) is filled with the suction gas pipe (6).
It is cooled and liquefied by the refrigerant flowing through e), and is stored in a certain amount as a liquid refrigerant. Furthermore, the liquid refrigerant stored in the metering tank (40) flows out into the defrost circuit during the defrost operation, which will be described in detail later, but after the end of the pump operation, the hot gas valve (21) is connected to the hot gas bypass circuit. When switching to the (2o) side, this can be done automatically based on the pressure difference between the high pressure in the metering tank (4o) and the low pressure in the defrost circuit.

In addition, the amount of refrigerant set by the above-mentioned metering tank (4o) is always suppressed to a range that allows steady operation after the defrost operation is completed, regardless of the operating conditions or conditions, and the defrost time becomes longer. The aim is to select the optimal number of people without any problems.

As described above, the capacity tank (40) is provided so as to branch from the high-pressure gas pipe (6e), in other words, from the refrigerant circulation path, and the #1 specified amount is provided without intervening an on-off valve in the refrigerant circulation path. By making it possible to store and release the K refrigerant in the tank (40), the number of on-off valves installed in the refrigerant circulation path is not increased, that is, the flow path resistance of the circulation path is increased due to the interposition of on-off valves. It has the advantage of not causing

Further, the hot gas valve (2I) is mainly an electric three-way valve, which can control the valve opening degree to the hot gas bypass path (20) from 096 to 10096 in proportion to the voltage, and the evaporator ( 4) A proportional control valve is used to adjust the capacity by controlling the amount of hot gas bypass to 4), and at the same time, allows the entire amount of refrigerant circulating during frosting to flow through the hot gas bypass path (20), as will be described later. It is controlled by the controller (22), auxiliary relay (2D input), and K. The hot gas valve (21) is PID controlled by a controller (22).

This PID control (proportional-plus
-integral -plus-derivative
e control ) refers to control in which the control signal is proportional to the sum of the error signal, its integral, and its specialized number.

In addition, in Fig. 1, (2B) is the suction gas pipe (6e)
A normally open solenoid valve installed in the capillary tube (
24) in parallel and interposed in the suction gas pipe (6C).

This solenoid valve (28) is configured to return the suction gas refrigerant to the compressor (3) via the capillary tube (24) by closing the solenoid valve (28), thereby reducing the amount of refrigerant circulation. The reason for reducing the amount of circulation is to prevent overload when the outside temperature is high, after defrosting, when steady operation is started, when the refrigerant is running, or when the high and low pressures of the refrigerant are high. Therefore, the amount of work of the compressor (1) decreases due to the decrease in the amount of circulation,
The high pressure and the current value of the compressor motor are reduced, and the operating range can be expanded.

The solenoid valve (28) detects the suction temperature of the evaporator (4), and closes when the suction temperature exceeds a certain value to reduce the circulation amount, and opens when the suction temperature exceeds a certain value. In particular, the opening/closing control may be performed by detecting the high or low pressure, or by detecting the air-cooled condenser (2) suction temperature, that is, the outside air temperature, and when the outside air temperature is above a certain level. It may be closed and opened when the value is lower than a certain value.

In Fig. 1, (68L) is a low pressure switch; (68L) is a low pressure switch;
8H) is a high pressure switch, (68CL) is a high pressure control switch, (68QL) is a hydraulic protection switch, and (6BW) is a water pressure switch. (22)
The on-off valve (BO) is closed by the defrost operation start command and the bongdakun operation is performed, and the end of the bongdakun operation and the defrost operation The start is mainly the low pressure switch (68L
).

The command to start the defrost operation uses the main air pressure switch (APS) and the defrost timer (2D), which is set to, for example, 12 o'clock. In this case, the air pressure switch (A
PS) is given priority over the defrost timer (2D), and is reset by the operation of the air brake switch (APS).

Furthermore, the end of the defrost operation can be accomplished by, for example, connecting two thermostats (2BD, ), (2BD, ), (2BD, ), (2BD, ), (2BD, ), (
28D, ) (not shown in FIG. 1) is used to detect the temperature of the low pressure gas pipe (6d).

Next, the electrical circuits of the controller (22) for regulating the temperature of the blown air by controlling the hot gas valve (21) and the respective control devices for controlling the defrost operation will be explained based on the diagram. do.

What is shown in FIG. 4 is the electrical circuit of the refrigeration system shown in FIG. Three indoor 7 unmoke (MF 1-1) + (MF
1-2) T (MF”-3) and the air-cooled condenser (2
) Three outdoor fan motors (MF2-1) corresponding to the three fans (11) attached to the (MF2-2
), (MF2-3), and the power supply circuits of these electric devices are for low voltage power supply of 200v or 220V.
0v high voltage power supply plug (P) and connect it to the power supply, and connect the transformer (T) to the power supply circuit.
The controller (22) and the control circuits of the respective control devices are connected through the controller (22) and the control circuits of the respective control devices.

In addition, in the IIrJ4 diagram, (CB) is the circuit breaker-1 (OC), the overcurrent relay-1 (2X,) to (2 people) are the auxiliary relays and their contacts, and (8-88) are the on and off switches. . Further, in the power supply circuit, the contacts without numbers are the plugs (P).

), (P, ) switching contact, (Y.

), (U, ), (G, ), (G, )
are both refrigerating operation and refrigeration operation changeover switches built into the controller (22), and (Yl) is a short-circuit wire.

Although not shown, the controller (22) is equipped with an input transformer, a power input device, a sensor power device, an operation input/output device, a central processing unit, and a relay output device, and the sensor power device includes a first As shown in the figure, there is a return sensor (R8) placed on the suction side of the evaporator (4) to detect the temperature of the return air from inside the refrigerator, that is, the suction air, and a sag sensor placed on the Suita side to detect the Suita air temperature. Licensor (S
A set point selector (PS) and an output display (DP) are connected to the operation input/output device, and the hot gas valve (S) is connected to the relay output device.
21) and the solenoid relay (205) of the solenoid valve (2B) in the embodiment shown in FIG.
S), auxiliary relay (2 people), (2 people) and lamp (AL
), (BL), and next o! J v-Inn mother [(A)
, (B) are interposed and connected.

■) Parallel circuit of the air brake rash switch (APS), defrost timer (2D), and manual defrost switch (3D) contacts that issue a command to start hot gas operation, and the normally open contact of the defrost relay (2DX), Thermostat (23ρ), (28D,
) and the defrost relay (2DX, ), and the compressor motor (M
For C), the normally closed contact and self-holding contact of the electromagnetic switch (88C) are connected in parallel through the parallel circuit with the auxiliary relay (2DX,), and each circuit is connected in series. circuit.

(Default zero strike control circuit) 2) Oil pressure protection switch (68QL), compressor protection thermostat (49), overcurrent relay (OC), high pressure switch (6
8H), a series circuit of the low pressure switch (68L) and the electromagnetic switch (88C) of the pressure #Iif machine motor (MC).

(Start/stop control circuit for pressure mia motor (MC)) Furthermore, the following two circuits are connected in series to the oil pressure protection switch (68QLI). That is, (i) the normally open contacts of the auxiliary relays (2 people) and the solenoid relay (20) of the on-off valve (80) for pump operation;
Series circuit with LS).

(Bonpu Dakun control circuit) ■) For the normally closed contact of the auxiliary relay (2D input), the evaporator (
4) Indoor fan motor (MFI-1) attached to...
circuit of the delay timer (2F) and the indoor 7 motor (MFI-1) at the contact point of the delay timer (2F).
...'s electromagnetic switch (88F) and differential zero strike timer (2
A circuit in which the parallel circuit with D) is connected in series.

(Fan motor and defrost timer control circuit) In addition, the electric part (20M) of the hot gas valve (21) is
The normally open contacts of the auxiliary relays (2 people) and '(2 people) are interposed, and the normally open contacts of the auxiliary relays (2DX, ) are interposed separately from the control circuit connected to the controller (22) K. 9J is forcibly changed to 100% opening during defrost operation. In Fig. 4, (CPD) is a contact protection diode, ( GL ), (R
L) is a lamp, and (8-8OL) is a lamp switch.

Therefore, in the above configuration, the air temperature is adjusted by the set point selector (
Depending on the set temperature set in PS), if the set temperature is lower than ti'-5°C during refrigeration operation, the compressor (1) will be started/stopped based on the return sensor (R5) on the suction side. In addition, in the case of refrigeration operation at 5°C or higher, the hot gas valve (21) is controlled to an opening of 0 to 100% based on the supply sensor (SS) on the Suita side, and the opening is adjusted according to this opening. This is done by bypassing the hot gas at a flow rate of

During such deep freezing or refrigeration operation, the evaporator (4) is activated for 70 hours, the air pressure switch (APS) is activated, or the defrost tie (2D) is activated. When a defrost operation start command is issued, the defrost operation is performed as follows.

This defrost operation will be explained according to the flowchart shown in FIG.

First, when a defrost operation start command is issued as described above, the defrost relay (2DX) is energized, the auxiliary relays (2) are deenergized, the pump control circuit is opened, and the solenoid of the on-off valve (80) is activated. Relay (20L
S) is demagnetized, the 1 Gtl valve closes (a o ) v = closed and pump down operation begins.0 In this pump down operation, the liquid refrigerant is transferred to the condenser (2),
('8), the liquid receiving part of the liquid receiver (7), and the on-off valve (
80), and the low pressure on the suction side of the compressor (1) decreases, and when the low pressure becomes lower than the set value of the low pressure switch (68L), The low pressure switch (68L) is turned off, the start/stop control circuit of the pressure IfiJ machine motor (MC) is opened, the electromagnetic switch (88C) of the motor (MC) is demagnetized, and the compressor (1) is turned off. stops, and pump-down operation ends.

As described above, a certain amount of liquid refrigerant is stored in the metering tank (40) during normal operation, and the metering tank (40) is connected to the discharge side of the pressure Mi@(1). Therefore, the liquid refrigerant stored in the metering tank (40) does not flow out during the pump-down operation.

Then, as the electromagnetic switch (88C) is demagnetized, its normally closed contact closes, so the auxiliary relay (2DX,) in the defrost control circuit is energized, and the hot gas valve (88C) is energized.
The electric part (20M) of 21) is operated and switched to 100% opening, and the hot gas valve (21) is operated by the controller (20M).
Regardless of the control of the hot gas bypass path (22)
) side, and the indoor 7 unmotor (MFl-
t)... stops.

As described above, when the hot gas valve (21) is fully opened to the hot gas bypass circuit (20) side, the liquid refrigerant stored in the metering tank (40) is gasified and flows out to the defrost circuit. That's what I do.

The reason why this liquid refrigerant gasifies and flows out to the evaporator (4) is that the volume of the defrost circuit is smaller than the volume of the metering tank (40).
) is relatively large compared to the volume of the refrigerant stored in the evaporator (4). Immediately after the hot gas valve (21) is switched, the liquid refrigerant becomes fluffy due to pressure drop, and as a result, the liquid refrigerant remains in the evaporator (4) in a liquid-gas mixed state. It will leak out to the side.

Due to this outflow, the low pressure pressure increases and the low pressure switch (
68L), the low pressure switch (68L) is turned on and the compression fi(1) is activated.
A certain amount of the refrigerant described above circulates through the defrost circuit, and defrost can be performed by the hot gas flowing into the evaporator (4) from the hot gas bypass path (20).

Since this defrost operation is performed using a predetermined amount of refrigerant from the quantitative tank (40)K, optimal defrost is always possible regardless of the operating state immediately before the defrost operation.

Note that during this defrost operation, even if some of the refrigerant is liquefied in the evaporator (4), gas-liquid separation is performed in the accumulator section (7b), so that liquid does not accumulate in the compressor (1).

When the defrosting is completed as described above, the thermostat (28D,) placed on the outlet side of the evaporator (4)
, (28 cu), thermostat with lower temperature setting (
28D, ) is activated, the defrost control circuit is opened, the defrost relay (2DX,) is demagnetized, the self-holding circuit of the auxiliary relay (2DX,) is also released, and the auxiliary relay (2 people) is energized. The normally open contact is opened, the solenoid relay (20LS) is energized, the on-off valve (80) is opened, and the refrigerating operation is returned to, or the hot gas valve (21) is closed during the refrigerating operation.
Then, the controller (22) shifts to opening degree control and returns to steady operation.

Note that when returning to steady operation after the defrost operation ends, the ambient temperature of the evaporator (4) is higher than in steady operation, but the refrigerant circulation amount during the defrost operation is controlled to a constant amount. Because of this, steady operation can always be performed reliably without the high voltage becoming abnormally high and activating the high voltage switch (68H) or overcurrent relay (OC).
In some cases, such as when the outside air temperature is abnormally high, the high pressure may become abnormally high even though the amount of refrigerant is controlled to be a constant amount. In this case, the setting of the amount of refrigerant may be reduced, but since this is a very rare case, in the embodiment illustrated in FIG. - Install a parallel circuit with the tube (24), close the solenoid valve ('2B) by detecting Suita air temperature, high pressure or low pressure, or outside air temperature, and control the refrigerant circulation amount through the capillary tube (24). The solenoid valve (28) has a solenoid relay (205S) connected to the auxiliary relay (205S) as shown in FIG.
The normally open contact of the defrost relay (2DX,) is connected in series with the parallel circuit of the processor (28A) that detects the Suita air temperature etc. via the normally closed contact of the defrost relay (2DX,). Depending on operating conditions in which the outside air temperature is abnormally high and the high pressure rises, the electromagnetic valve (28) is closed to enable operation by reducing the amount of refrigerant circulation, thereby expanding the operable range.

Furthermore, in the embodiment shown in FIG. 4, when the defrost operation is completed and the transition is made to freezing or refrigeration operation, since the evaporator (4) and its surrounding temperature are high, the low pressure increases, and as a result, the high pressure increases. In order to prevent the high voltage switch (68H) and overcurrent relay (OC) from operating, the electromagnetic switch (
Since the auxiliary relay (88F) is about to be connected in series with the normally closed contact of the auxiliary relay (2DX,) via the contact of the delay timer (2F), the auxiliary relay (
2D input) is demagnetized and its normally open contact closes, the indoor fan motor (MFl-t) is not driven immediately but is delayed for a predetermined period of time to cool the evaporator (4) and the surrounding air to some extent. After that, it will be driven.

In addition, as a method of delaying the indoor fan motor (MFl-t), in addition to using the delay timer (2F) as described above, there is no constant pressure control other than the high pressure switch (68H) or the low pressure switch (68L). A modified high-pressure switch or low-pressure switch may be provided and delayed by these switches.

Note that the metering tank (40) may be arranged in a manner other than that in the above embodiment as shown in FIG. 2.8.

That is, in the example shown in FIG. 2, the metering tank (40) is attached to the suction gas pipe (6e) similarly to the one shown in FIG. (
6a) from the compressor (1) to the hot gas valve C21)K, and the other side of the metering tank (4o) is a refrigerant pipe that constitutes a defrost circuit, such as a real gas bypass circuit (20). It is connected to via an electromagnetic on-off valve (26).

In this case, the on-off valve (26) is closed during normal operation,
After the Bongdakun operation is completed by the def zero stroke start command, the hot gas valve (21) is connected to the hot gas bypass circuit (20).
It opens at the same time as it fully opens to the side, and then opens again at the same time as the defrost operation ends.

In order to do this, the electric circuit corresponding to the refrigeration system shown in FIG. relay(
2DX, ) and the electric part (20DS) of the on-off valve (26)
) by additionally connecting a series circuit.

In addition, in the case shown in FIG. 8, the metering tank (40) is attached to the suction gas pipe (6e) in the same manner as described above, while the metering tank (40) is connected to the high pressure gas pipe (6e) or the condenser. From (2) and (8), the on-off valve for Bonpugukun operation (
80) and the first on-off valve (27) in the liquid pipe section (6C).
and the other side of the metering tank (40) is connected to a refrigerant pipe constituting a defrost circuit, such as a low pressure gas pipe (6d), via a second on-off valve (28) and a capillary tube (29). In this case, during normal operation, the first on-off valve (27) is opened, and
The second on-off valve (28) is closed, and after the end of the bongdakun operation according to the defrost operation command, the hot gas valve (21) is switched to the hot gas bypass circuit (20) side and the first on-off valve (27) is simultaneously closed. ) is opened and the second on-off valve (28) is closed, and at the same time as the defrosting operation is completed, the first on-off valve (27) is opened again and the second on-off valve (28) is closed. That's what I do.

In order to avoid this, the electric circuit corresponding to the refrigeration system shown in FIG. 8 is connected between the busbars (A) and (B) of the relay output device of the electric circuit shown in FIG. 4, as shown in FIG. 6. A series circuit of the normally closed contact of the auxiliary relay (2DX,) and the electric part (20DS,) of the first on-off valve (27), and the auxiliary relay (20DS,),
It is configured by additionally connecting the normally closed contact of the 2DX, ) and the series circuit of the electric part (20DS,) of the second on-off valve (28).

The embodiment shown in Fig. 2.8 described above has the same effect as the embodiment shown in Fig. 1, but the embodiment shown in Fig. 1 has an electromagnetic on-off valve in the metering tank (40). It is superior to other systems in that the liquid refrigerant can be stored in the metering tank (40) without using a tank (40), and the liquid refrigerant can be discharged from the tank (40).

That is, it is advantageous in that the number of electromagnetic on-off valves that are prone to failure can be reduced.

In the embodiment described above, the opening degree control of the hot gas valve (21) is performed using a Dougray sensor (
SS) is used to compare the temperature with the set temperature, but a pressure sensor that detects the low pressure or high pressure of the refrigerant may be used, or the difference between the suction air temperature and the Suita air temperature may be used. This may be done by detecting.

In addition, although an electric three-way valve is used as the hot gas valve (21), two two-way valves may be used in combination.Although the above embodiment is applied to a container refrigeration system, other refrigerating poles may also be used. In addition, as the condenser, an air-cooled condenser (2) and a water-cooled condenser (8) were used together, but a single condenser (2) or (8)
) may also be used.0 As described above, the present invention provides an on-off valve (30) on the downstream side of the condensers (2) and (8), which closes in response to a command to start defrost operation, so that the condensation can be performed by pump-down operation. if% (2)
, (8), and a metering tank (4) that stores a certain amount of refrigerant and drains this refrigerant to the defrost circuit that performs defrost operation.
0), and the defrost operation is performed with a constant amount of refrigerant, so the defrost operation can always be performed optimally regardless of the immediately preceding operating state.

In other words, even if the amount of hot gas bypassed to the evaporator (4) is large or small (including zero), defrost operation is performed by controlling the amount of refrigerant to a constant amount that is optimal for defrost operation, so the amount of refrigerant at the end of defrost is The compressor motor (MC) will not become inoperable due to an abnormal increase in high pressure or excessive current flowing through the compressor motor (MC), and will always return to normal operation, and the amount of refrigerant circulated during defrost operation will be reduced. This also solves the problem that defrosting takes a long time.

Furthermore, while the amount of refrigerant is optimal during defrost operation, it does not circulate an unnecessarily large amount of refrigerant.
The pressure M4ia input can be reduced accordingly, making it possible to defrost without wasting power.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant piping system diagram showing one embodiment of the refrigeration system of the present invention, FIG. 2 is a refrigerant piping system diagram showing another embodiment, and FIG. 8 is a refrigerant piping system diagram showing still another embodiment. Figure IIIJ4 is the electrical circuit diagram of the refrigeration system shown in Figure 1, and Figure 5 is the electrical circuit diagram of the refrigeration system shown in Figure 2.
FIG. 6 is a partial diagram of the electric circuit related to the refrigeration device shown in FIG. 3, and FIG.
The figure is a flowchart of defrost operation, and FIG. 8 is a refrigerant piping system diagram showing a conventional example. (1)・・・・・・・・・・・・Compressor (2),
(8) Condenser (4) Evaporator (20)
・・・・・・・・・Hot gas bypass path (21
)・・・・・・・・・Hot gas valve (80)...
・・・・・・・・・Opening/closing valve (40)・・・・・・・・・
・・・・Quantitative tank, “′・, Agent Patent attorney Tsu 1) Hisashi Nao ′1,1”, 1goi
″′JI J':'! ′j゛・2([・j

Claims (1)

[Claims] (1) A hot gas bypass path (20) that bypasses the hot gas discharged from the compressor (1) to the evaporator (4) by bypassing the condensers (2) and (8), and the bypass A refrigeration system equipped with a hole gas valve (21) which controls the amount of hot gas flowing from the passage (20) to the evaporator (4) to control the capacity and performs a defrost operation in all cases during frosting. In the apparatus, the condenser c
An on-off valve (80) is provided on the downstream side of 'z) and (s>, which closes in response to a defrost operation start command, so that the refrigerant is confined in the liquid reservoir including the condensers (2) and (8) during bongdakun operation. On the other hand, a metering tank (40) is provided to store the optimum amount of refrigerant required for the differential J-stroke.
0) is connected to the discharge side of the compressor (1), and a defrost operation is performed with a constant amount of refrigerant stored in the tank (40).