JPS6129655A - 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] (Industrial Application Field) The present invention relates to a refrigeration system, specifically a defrost circuit having a gas bypass path and a defrost circuit disposed downstream of a condenser. The present invention relates to a refrigeration system which is equipped with a closing valve and which confines refrigerant unnecessary for defrost operation in a liquid reservoir including the condenser during pop-down operation, and performs defrost operation using a certain portion of the refrigerant present in the defrost circuit.

(Prior Art) The applicant of the present application has developed a refrigeration system that can always perform proper defrost operation without being affected by the operating state immediately before shifting to defrost operation, and has filed a patent application (Japanese Patent Application No. 717
70), and Fig. 4 schematically shows the outline of the device. The condenser (B) is connected between the high-pressure gas pipe (!:
), in a refrigeration system provided with a hot gas bypass path (F) that bypasses a liquid receiver (D) and an expansion valve (E), a connecting portion of the hot gas bypass path (F) with the high pressure gas pipe is provided. , a hot gas valve (G) that controls the hot gas bypass amount to the evaporator (G) and circulates the entire amount of circulating refrigerant to the evaporator (C) during frosting; ) is equipped with an on-off valve (H) that closes in response to a command to start defrost operation, and pumps a certain amount of refrigerant out of the refrigerant trapped in the liquid reservoir including the condenser (B) by pump-down operation. , a quantitative outflow mechanism (I) that flows out into the defrost circuit that performs defrost operation, and the compressor (A) that performs pump-down operation when the low pressure in the defrost circuit becomes below a set value due to pump-down operation. A low pressure switch (J) is provided to start the defrost operation when the low pressure in the defrost circuit becomes higher than the set value due to the outflow of refrigerant from the quantitative outflow mechanism (I). When performing defrost operation with operation,
The defrost operation is performed by circulating a predetermined amount of refrigerant through the defrost circuit through the quantitative outflow mechanism.

(Problem to be Solved by the Invention) However, in the above-mentioned second refrigeration system, for example, the temperature inside the compartment shown in FIG. There is no problem if the temperature is set higher than (-22.5°C), for example, -20'C, but the temperature inside the refrigerator is saturated at a pressure equivalent to the set pressure at which the low pressure switch (J) turns on. If the temperature is set to, for example, -25°C, which is lower than the temperature (-22.5°C), even if the on-off valve (H) of the low-volume outflow mechanism (I) is opened, the inside of the defrost circuit is The pressure is increased to the set pressure for turning on the low pressure switch (J). Therefore, the defrost operation will not start until the internal temperature naturally rises above -22.5°C, and the pump as a whole will There has been a problem in that it takes time from the end of the down operation to the start of the defrost operation.

The present invention has been made in view of the above problems, and when the temperature inside the refrigerator is set lower than the saturation temperature corresponding to the set pressure at which the low pressure switch turns off, the area around the evaporator is forcibly removed. By heating, the purpose is to promptly start defrost operation after pump-down operation ends.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a defrost circuit having a hot gas bypass path (20) and a condenser (2).
is provided with an on-off valve (30) that is disposed downstream of the defrost operation and closes upon a defrost operation start command, and traps refrigerant unnecessary for the defrost operation in a liquid reservoir including the condenser (2) during pump-down operation; In a refrigeration system that performs defrost operation using a certain amount of refrigerant existing in the defrost circuit, detecting a decrease in low pressure due to pump-down operation and turning off the pump-down operation to terminate the pump-down operation,
A low pressure detector (S'OL) is provided that detects an increase in low pressure and turns on to start defrost operation, and during the period from the off operation to the on operation of the low pressure detector (SOL), (4) A heating means for heating the surrounding air was provided.

(Function) According to the present invention, the evaporator (4) is heated by the heating means.
) by forcibly heating the surrounding air to accelerate the ON operation of the low-pressure pressure detector (63L) that is in the OFF operation, and perform defrost operation using a certain amount of refrigerant, regardless of the set temperature inside the refrigerator. You can start quickly.

(9 actual cases) 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 (12 is a compressor, (2) is an air-cooled condenser, (3) is a water-cooled condenser, (4) is an evaporator, (5) is a temperature-sensitive expansion valve having a temperature-sensing part (5 pieces), and each of these devices is connected by a refrigerant pipe (6), and the evaporator (4) cools the air inside the refrigerator. forming a cycle.

Further, in FIG. 1, (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) is a fan attached to the suction side of the evaporator (4), and (11) is a fan attached to the air-cooled condenser (2).

In the refrigeration cycle configured as shown below,
A high pressure gas pipe (6a) connecting the discharge side of the compressor (1) and the inlet side of the air-cooled condenser (2) carries the hot gas discharged from the +iiij compression compressor to each of the condensers ( 2)
(3) Connect a hot gas bypass path (20) that bypasses the liquid receiving part (7a) of the liquid receiver (7) and the temperature-sensitive expansion valve (5) and leads to the evaporator (4) described in 01j. , its outlet side is connected to the low pressure liquid pipe (6b) between the expansion valve (5) and the evaporator (4), and the hot gas bypass path (20) is connected to the high pressure gas pipe (6a). A hot gas valve (21) is installed at the connection point of the refrigeration operation or refrigeration operation stop command on the downstream side of the condenser (3), that is, on the downstream side of the liquid indicator (9) in FIG. and an electromagnetic on-off valve (30) that closes when a defrost operation start command is provided to enable pump-down operation, and includes the condenser (2) (3) and the liquid receiving part (7a) of the liquid receiver (7). The refrigerant is trapped in the liquid reservoir, and a certain amount of the refrigerant trapped in the liquid reservoir is transferred to the defrost circuit that performs defrost operation, namely the compressor (1) and the hot gas valve (21).
), a hot gas bypass path (20), an evaporator (4), and a quantitative outflow mechanism (40) that flows out into a defrost circuit consisting of an accumulator section (7b) of a liquid receiver (7).

The hot gas valve (21) is mainly an electric three-way valve, and the hot gas bypass path (20
) can be controlled from 0% to 100%, and the amount of hot gas bypassed to the evaporator (4) is controlled to adjust the capacity, and the entire amount of refrigerant circulated during frosting is transferred to the hot gas. A controller (22), which will be described later, uses a proportional control valve configured to flow through the bypass path (20).
It is controlled by the auxiliary relay (2DX2) of the defrost control circuit. In addition, the hot gas valve (
21) is subjected to PID control by a controller (22).

This PID control (Proportional-plus
-integrate-plus-derivative
control), u refers to control in which the control signal is proportional to the sum of the integral of the deviation signal and its function.

Further, the fixed amount outflow mechanism (40) may be configured, for example, by the on-off valve (
Among the liquid reservoirs that perform pump-down operation and confine refrigerant by closing 3 O), an electromagnetic on-off valve is installed at a position where a predetermined outflow amount can be obtained with respect to the intervening position where the on-off valve (30) is installed. (41), and the first
In the figure, the on-off valve (30) is replaced by the expansion valve (5).
Interposed in the high pressure liquid pipe (6c) on the inlet side of the
The on-off valve (41) is connected to the liquid indicator (9).
A certain amount of refrigerant is interposed in the high pressure liquid pipe (6c) on the outlet side of the refrigerant and confined in the high pressure liquid pipe (6c) between these interposed positions.
The on-off valve (41) is closed and the on-off valve (30) is opened to allow outflow.

The amount of refrigerant set by the fixed amount outflow mechanism (40) is determined so that the steady operation performed after the defrost operation is always carried out regardless of the operating state. That's what I do.

Further, the quantitative outflow mechanism (40) utilizes the high-pressure liquid pipe (6C) and the on-off valve (41) to operate the on-off valve (3).
0), or it may be configured on the low pressure liquid pipe side as long as it is downstream of the condenser (2) or (3), in other words, downstream of the part that becomes the liquid reservoir, or it may be configured on the low pressure liquid pipe side. Alternatively, the refrigerant circulation path may be formed using special piping or a liquid reservoir without using a liquid pipe.

In Fig. 1, (23) is a non-energized solenoid valve installed in the suction gas pipe (6e), and the capillary tube (24
) is connected in parallel with the suction gas pipe (6e).

This solenoid valve (23) is configured to return the suction gas refrigerant to the compressor (1) via the capillary tube (24) by closing the solenoid valve (23), thereby reducing the amount of refrigerant circulation. The reason for reducing the circulation amount in this way is to prevent overload due to high and low pressures of the refrigerant when the outside temperature is high, when steady operation is started after defrosting, or during pulldown. Due to the reduction in the amount of circulation, the amount of work of the compressor (1) is reduced, the current value of the high-pressure single blade and the compressor motor is reduced, and the operating range can be expanded.

The electromagnetic valve (23) detects the suction temperature of the evaporator (4), closes when the suction temperature exceeds a certain level, and reduces the circulation amount, and when the suction lQ degree falls below the fixed value. The opening/closing may be controlled by detecting high pressure 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 configured to close and open when the value is lower than a certain value.

Accordingly, the present invention provides a refrigeration system configured as described below, which detects a drop in the low pressure of the defrost circuit due to pump-down operation, turns off the defrost circuit when it is below a predetermined set value, and terminates the pump-down operation; and a low pressure switch (63L) that detects an increase in the low pressure of the defrost circuit due to the outflow of refrigerant from the quantitative outflow mechanism (40) and turns off when the defrost circuit exceeds a predetermined set value to start defrost operation. ), and the ambient temperature of the evaporator (4) constituting the defrost circuit is increased during the period from the OFF operation to the ON operation of the low pressure pressure detector (SOL). Therefore, an additional /71λ means is provided.

In the embodiment shown in the figure, the pressure detection section of the low pressure pressure detector (SOL) is connected to the compressor (
1), while the low-pressure pressure detector (SO
The setting value for off operation of L) is O, 12kg/C11”
(400m++Hg) Also, set the ON operation setting value to 0.
36kg/cm".

The heating means shown in the figure is a fan motor (MFI-, ) (MFl-, ) (MFI-3) of a fan (10) (10) (10) attached to the suction side of the evaporator (4). The fan motor (MFI-,)(MFI-,)(
The ambient temperature of the evaporator (4) is heated by the heat generated by driving the MFI-3).

In the figure, (63H) is a high pressure switch, (63L) is a high pressure control switch, (63QL) is a hydraulic protection switch, and (63L) is a high pressure control switch.
3W) is a water pressure switch.

In the above configuration, the hot gas valve (21) is controlled by an output signal from the controller (22) and a defrost operation start command, and the opening/closing valve (30) is controlled by the defrost operation start command. Closed pump down operation is performed, and the defrost operation start command is mainly issued by Air Presso/Yasuinochi (A
For example, a defrost timer (2D1) whose set time is 12 hours is used. In this case, the air plenum Yasuinochi (APS) is given priority over the defrost timer (2D), and the air plenum
The defrost timer (2+) is activated by the operation of the APS.

Further, the end of the defrost operation can be completed by, for example, connecting two thermostats (23D,
2) is attached to detect the temperature of the low pressure gas pipe (6d).

Next, the electric 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 FIG.

What is shown in FIG. 2 is an electric circuit of the refrigeration system shown in FIG.
4) Three indoor fan motors (MFI-,) corresponding to the three fans (10) attached to (MFI-,)
(MFl-,) and three outdoor fan motors (MF2-, ) (MF2-,) (MF2-,) corresponding to the three fans (11) attached to the air-cooled condenser (2)...
electrical equipment, and the power supply circuit for these electrical equipment is 20
0■ or 220V low voltage power supply plug (Pl) and 38
0-415 V Also Ha440 V (7) X 'El
One of the voltage source plugs (P2) is selected and connected to the TL source, and the controller (22) and the control circuits of the control devices are connected to the power supply circuit via a transformer (Tr). .

In addition, in Fig. 2, (CB) is circuit breaker-1.
(OC) is an overcurrent relay, (2X1) to (2X3) are auxiliary relays and their contacts, and (3-88) is an on/off switch. Further, in the power supply circuit No. 2, the contacts without reference numerals are switching contacts that are switched by selecting the plug (P, ) (P2).

Although not shown, the controller (22) includes 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 return sensor (R8) placed on the outlet side to detect the temperature of the blown air. Sensor (SS
) is connected to the operation input/output device, a seven node point selector (CPS) and an output display device (DP) are connected to the operation input/output device, and the solenoid relay ( 20LS,) control relay (Y,
), switching relay (Ul
) Other relays (G,) (G,) and short circuit wires (Y,) are included, and these include the electric part (20M) of the hot gas valve (21) and the electric part (20M) in the embodiment shown in FIG. Solenoid relay (20SS) of the solenoid valve (23), auxiliary relay (2X,) (2X,) and lamps (AL) (BL)
is connected.

It also consists of the following relay circuit.

1) Parallel circuit of the normally open contacts of the auxiliary relay (2'X4) (2DX2) and the on-off valve (3) for pump-down operation
Series circuit with 0) solenoid relay (20LS, ).

(Pump-down control circuit) 2) Contact points of air plane/yasu inch (APS), defrost timer (21, ), manual defrost switch (3D), and defrost relay (2DX, ), which issues a command to start defrost operation
A parallel circuit of normally open contacts, a series circuit of a thermostat (23D,) (23D,) that detects the end of defrost, and a timer (2D2) that ends defrost operation at a predetermined time (for example, 45 minutes) after a defrost operation command is issued. Through a parallel circuit of the defrost relay (2DX,) connected in series to the contact of the timer (2, D2), the normally closed contact of the electromagnetic switch (88C) for the compressor motor (MC), and the self-holding contact. Auxiliary relay connected in parallel (2D x 2)
Ell+: A series circuit in which each circuit in the parallel circuit is connected in series to iJ and the auxiliary relay (2DX3) connected in series to the self-holding contact of the auxiliary relay (2DX, ). (Defrost Control Circuit) The auxiliary relay (2DX3) described above is for ensuring that the delay timer (2F) of the fan motor (MF1=) is in the OFF state during defrosting.

3) Compressor protection thermostat (49), overcurrent relay (O
C), high pressure switch (63H), and the low pressure pressure detector (
A series circuit with the low pressure switch (63L), the first hydraulic protection switch (83QL-1), and the electromagnetic switch (88C) of the compressor motor (MC) that constitute the SOL. (Compressor motor (MC) start/stop control circuit) 4) A fan in the evaporator (4) connected in series to a normally closed contact of the auxiliary relay (2DX,) to a normally closed contact of the auxiliary relay (2DX,). The delay timer (2F) circuit of the motor (MFl-1)... and the on-off valve (41
) The circuit of the solenoid relay (20LS, ) and the contact point of the delay timer (2F) of the indoor fan motor (
A circuit in which a three-way parallel circuit is connected in series with a circuit in which parallel circuits of an electromagnetic switch (88F) and a defrost timer (2D) are connected in series. (Mainly the quantitative outflow control circuit) The quantitative outflow control circuit is connected in series to the first hydraulic protection switch (63QL-1).

5) The normally closed contact of the auxiliary relay (2DX) and the normally closed contact of the electromagnetic switch (88C) are connected in series to connect the first hydraulic protection switch (63QL-1) and the fixed amount outflow control circuit. The indoor fan motor (MFI-
A circuit connected in series to the parallel circuit of the electromagnetic switch (88F) and the defrost I/timer (2+), ).

(Heating means control circuit) In Fig. 2, (CPD) is a contact protection diode, (GL) is a lamp, (3-3OL
) is a lamp switch, and (63QL-2) is a hydraulic protection switch.

Moreover, the electric part (20M) of the hot waste valve (21) is
Separately from the control circuit of the controller (22), a direct connection circuit is formed in which the normally closed contact of the auxiliary relay (2DX) is interposed, and the opening degree can be switched to 100%.

Therefore, in the second configuration, the air temperature can be adjusted by using the cent point selector (22) of the controller (22).
Depending on the set temperature set by CPS), in the case of refrigeration operation where the set temperature is lower than, for example, -5°C, the compressor (1) is controlled to start and stop based on the return sensor (R8) on the suction side. In addition, in the case of refrigeration operation at temperatures below 5°C, the hot gas valve (21) is controlled at 7 degrees (0 to 100%) based on the supply sensor (SS) on the outlet side, and during this period the melon This is done by bypassing the hot gas at a corresponding flow rate.

When the freezing or refrigerating operation is performed in this way, the evaporator (4) transfers the floss 1 to the air pre-cooler.
When the APS (APS) is activated or the defrost timer (21) is activated and a command to start the defrost operation is issued, the defrost operation is performed as follows.

Next, this defrost operation will be explained.

First, as described above (when a defrost operation start command is issued, the timer (2D,) that controls the defrost operation is activated, and at the same time, the auxiliary relay (2X4) is demagnetized by the excitation of the defrost relay (21)X,). Accordingly, the pump-down control circuit is opened, so the solenoid relay (20LS, ) of the on-off valve (30) is demagnetized, the on-off valve (30) is closed, and pump down operation begins. At this time, the start/stop control circuit of the compressor motor (MC) is closed, and the electromagnetic switch (88) of the compressor motor (MC) is closed.
Since the auxiliary relay (2DX2) is demagnetized by the excitation of C), the solenoid relay (2DX2) of the on-off valve (40)
0LS2) is excited and the on-off valve (41) is open.

In this pump-down operation, the liquid refrigerant is transferred to the condenser (2) (
3) and the liquid receiving part of the liquid receiver (7) and the on-off valve (30)
At the same time, the low pressure on the suction side of the compressor (1) decreases, and the low pressure becomes lower than the set value of the low pressure switch (63L).
Suddenly, the low pressure switch (63L) constituting the low pressure pressure detector (SOL) turns off, and the compressor motor (M
The start/stop control circuit C) is opened, the electromagnetic switch (88G) of the motor (MC) is demagnetized, the compressor (1) is stopped, and the pump-down operation is completed.

By demagnetizing the electromagnetic switch (88C), the normally closed contact of the electromagnetic switch H3 (88C) incorporated in the defrost control circuit closes, and the auxiliary relay (2DX2) in the defrost control circuit is energized. Therefore, the electric part (20M) of the hot gas valve (21) operates, and the hot gas bypass path (20M) operates regardless of the control of the controller (22).
At the same time as fully opening to the 2o) side, the normally open contact of the auxiliary relay (2DX, ) incorporated in the quantitative outflow control circuit opens to open the quantitative outflow control circuit, and along with this, 1) 1i
The solenoid relay (2oLs,) of the on-off valve (41) constituting the memorized amount outflow mechanism (40) is closed and the on-off valve (41) is closed, while the auxiliary relay (21) X2 in the pump-down control circuit ) is closed to open the pump-down control circuit, and the on-off valve (3o
The solenoid relay (20LS, ) of ) is energized to open the on-off valve (30).

As a result, a certain amount of liquid refrigerant trapped in the high-pressure liquid pipe (6c) between the on-off valves (41) and (30) is gasified and flows out into the defrost circuit.

Then, when the pump-down operation is completed and the electromagnetic opening/closing mechanism (88C) is demagnetized, the NIII auxiliary relay (2DX, ) is energized as described in 2.
While the normally closed contact connected in series to the switch (88F) of 2) opens, the auxiliary relay (2DX2) connected in parallel to the normally closed contact and incorporated in the heating means control circuit
Since both the normally open contact of the electromagnetic switch (88C) and the normally closed contact of the electromagnetic switch (88C) are closed, the heating means connection circuit is closed, and the fan motor (MFl-) attached to the evaporator (4) is closed.
1) The excitation of the electromagnetic switch (88F) of... is continued, and the fan motor (MFI-, )... is continuously driven, and the fan motor (MFI-1) is driven. The heat generated heats the air surrounding the evaporator (4).

Therefore, even if the temperature inside the refrigerator is
Even if the temperature is set lower than the saturation temperature corresponding to the set pressure for turning on the evaporator (4), the air surrounding the evaporator (4) is immediately heated by the driving heat of the fan motor (MFI-, )... Therefore, the low pressure within the defrost circuit quickly rises to a level higher than the set pressure at which the low pressure switch (63L) turns on.

On the other hand, as described above, when the low pressure in the defrost circuit rises to - and becomes higher than the set value at which the low pressure switch (63L) is turned on, the low pressure switch (Ei 3 L) is turned on and the compressor motor (63L) is turned on. The electromagnetic switch (88C) is excited by the closing of the start/stop control circuit of the MC), and the compressor (1) is accordingly restarted, a certain amount of refrigerant circulates through the frost circuit, and the hot gas Bypass path (2o)
At the same time when the defrost operation is started by the hot scum flowing into the evaporator (4), the electromagnetic switch (88C)
The above built into the heating means control circuit by the excitation of the
Electromagnetic opening and closing! The normally closed contact of (88C) opens, the heating means control circuit opens, and the fan motor (MFI-, )
...or it will stop.

Note that this defrost operation is performed by the quantitative outflow mechanism (40).
This is because a certain amount of refrigerant is used. Related to the operating state immediately before defrost operation (
This allows for optimal defrost at all times.

Also, during this differential thrust operation, even if some of the refrigerant is liquefied in the evaporator (4), gas-liquid separation is performed in the accumulator section (7b), so no liquid backflow to the compressor (1) occurs. .

Then either the thermostat (23D, ) (23r; 1.) provided on the output 1 side of the evaporator (4) is activated or the timer (2D) is activated to control the defrost operation.
, ) open the defrost relay (2DX,'
When I is demagnetized, the defrost control circuit is opened and the self-holding circuit of the auxiliary relay (2DX2) is also released, so the solenoid relay (20LS,)
(20LS,,) are both excited, and the on-off valve (3
0) (41) is opened, and at the same time the defrost operation ends, the operation returns to the freezing operation, or during the refrigeration operation, the real gas valve (21) shifts to the opening control by the controller (22) and returns to steady operation. I will return.

Note that when returning to normal operation after the end of this defrost operation, the ambient temperature of the evaporator (4) is at a temperature controlled level compared to that of normal operation, but the amount of refrigerant circulated during the defrost operation is controlled to a constant amount. Therefore, steady state operation can always be performed reliably without the high voltage becoming abnormally high and activating the high voltage switch (63H) or overcurrent relay (QC). However, when the outside temperature is high, etc. Even though the amount of refrigerant is controlled to a constant amount, the high pressure may become abnormally high. In this case, the setting of the refrigerant amount may be reduced, but
Since this is a very rare case, in the embodiment shown in FIG.
3) and a capillary tube (24), the solenoid valve (23) is closed by detecting the temperature of the blown air, high or low pressure, or outside temperature, and the refrigerant is supplied through the capillary tube (24). It is designed to reduce the amount of circulation,
In addition, the solenoid valve (23) is connected to the solenoid relay (20SS) as shown in FIG.
The defrost relay (2D
The solenoid valve (23) is connected in series through the normally closed contact of X,). Therefore, depending on the operating conditions where the outside temperature is abnormally high and the high pressure increases by 1, the solenoid valve (23) is closed and the amount of refrigerant circulated is reduced. It is now possible to operate the vehicle by reducing the amount of fuel, thereby expanding its operable range.

In addition, in the embodiment shown in FIG. 2, when the defrost operation is completed and the freezing operation or refrigeration operation is started, the evaporator (4) and its surrounding temperature are high, so the low pressure rises by 11 units, and as a result, the High pressure increases by 1, high pressure switch (63H),
To prevent the overcurrent relay (QC) from operating,
The electromagnetic closed air (88F) of the indoor fan motor (MFl-,) is connected in series with the normally closed contact of the auxiliary IJ L-(2DX,) via the contact of the delay timer (2F). Because of the connection, the auxiliary relay (2DX,) is demagnetized when the defrost operation ends, and even if its normally closed contact is closed, the indoor fan motor (MFI-,)... is not driven immediately and remains for a predetermined period of time. The evaporator (4) and the surrounding air are cooled to some extent after a delay before being driven.

In the following embodiments, a fan motor (MFl) of a fan (10) installed in the evaporator (4) is used as a heating means for heating the air surrounding the evaporator (4). -1)...
* is used, but the present invention is not limited thereto, and for example, a heater may be provided in the evaporator (4) as the heating means.

In addition to the embodiments described above, refrigeration equipment that confines refrigerant unnecessary for defrost operation in a liquid reservoir including a condenser (2) and performs defrost operation with a certain amount of refrigerant may be used, for example, in the embodiments shown in FIGS. The one shown in (d) may also be used.

The one in Fig. 3(a) has an open 11'1 valve (3o) at 11'.
After completing the pump down operation, the solenoid valve (61)
After opening the capillary (62) and supplying a certain amount of refrigerant necessary for defrost operation from the circuit (70) to the defrost circuit, the solenoid valve (61) is closed.

In FIG. 3(1)), the on-off valve (30) is closed to leave a certain amount of refrigerant necessary for the defrost operation, thereby ending the pump-down operation.

Fig. 3(c) shows that a refrigerant tank (64) with a fixed amount of heat exchanged with the suction pipe of the compressor (1) is connected to the discharge gas pipe through a connecting pipe (65), and a fixed amount of refrigerant is transferred during freezing or refrigeration operation. The refrigerant in the refrigerant tank (64) is stored in the refrigerant tank (64), and after the pump-down operation is completed, the refrigerant in the refrigerant tank (64) is returned to the defrost circuit through the communication pipe (65). If the refrigerant is difficult to flow out in this circuit, connect the communication pipe (67) with the solenoid valve (66) shown in dotted lines to the hot gas bypass pipe (20), and after the end of the pump-down operation, close the solenoid valve (67). 66)
You can also open it.

Fig. 3(d) shows that the inlet of the refrigerant tank (64) provided in the suction pipe is connected to the inlet side of the condenser (2), and the outlet is connected with a solenoid valve (67) and a capillary (68). pipe (69)
and connected to the suction pipe.

Furthermore, the described embodiment is based on the hot gas valve (21).
The opening degree of the refrigerant is controlled by using a supply sensor (SS) that detects the temperature of the blown air and comparing it with a set temperature, but a pressure sensor that detects the low or high pressure of the refrigerant may also be used. Alternatively, the detection may be performed by detecting the difference between the intake air temperature and the blown air temperature.

Further, although an electric three-way valve is used as the hot gas valve (21), two two-way valves may be combined.

Further, the above embodiments are applied to container refrigeration equipment, and can also be applied to other refrigerators.

Further, as the condenser, an air-cooled condenser (2) and a water-cooled condenser (3) were used in combination, but a single condenser (2) or (3) was used in combination.
) may be used alone.

(Effects of the Invention) As described above, the present invention detects a decrease in the low pressure due to the pump down operation, turns off the pump, terminates the pump down operation, and at the same time, the low pressure caused by the refrigerant flowing out from the fixed amount outflow mechanism (40) A low-pressure pressure detector (SOL) is turned on to start defrost operation upon detecting the rise in -h of the evaporator (4). Since a heating means for heating the surrounding air is provided, for example, even if the temperature inside the box is set to a temperature lower than the saturation temperature corresponding to the set pressure at which the low-pressure pressure detector (SQL) turns on. , the above addition
! By means of 11, the area around the evaporator (4) is forcibly heated to quickly turn on the low pressure detection (SOL), thereby speeding up the start of the defrost operation, thus shortening the overall time required for defrosting. can be made shorter.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant piping system diagram showing an embodiment of the refrigeration system of the present invention, Fig. 2 is an electric circuit diagram of the refrigeration system shown in Fig. 1, and Figs. ) is a refrigerant piping system diagram of another embodiment of the refrigeration system of the present invention, FIG. 4 is a schematic explanatory diagram showing a conventional example, and FIG. (2) It is a graph showing an increase in the pressure of the refrigerant flowing out from the outflow mechanism into the defrost circuit. (4)...Evaporator (20)...Hot gas bypass path (30)...
...Opening/closing valve (40) ...Quantitative outflow mechanism (SOL) ...Low pressure pressure detector J
1 Ward Ward Q gun

Claims (1)

[Claims] It is equipped with a defrost circuit having a hot gas bypass path (20) and an on-off valve (30) which is disposed downstream of the condenser (2) and closes when a defrost operation start command is issued. ) In a refrigeration system that confines refrigerant unnecessary for defrost operation in a liquid reservoir containing a liquid, and performs defrost operation using a certain amount of refrigerant existing in the defrost circuit, the system shuts off when a drop in low pressure due to pump-down operation is detected. and terminates the pump-down operation, and detects an increase in low pressure and turns on;
A low-pressure pressure detector (SOL) is provided to start the defrost operation, and a heating means is provided to heat the air surrounding the evaporator (4) during the period from the OFF operation to the ON operation of the low-pressure pressure detector (SOL). A refrigeration device characterized by: