JPH01174869A - Refrigerator - Google Patents

Abstract

PURPOSE:To feed out refrigerant to a defrosting circuit in a short time, and to eliminate an increase in a defrosting time due to insufficient refrigerant amount by forcibly feeding out the refrigerant weighed by a weighing unit with the discharging pressure of hot gas to be discharged from a compressor. CONSTITUTION:A refrigerant amount necessary for a defrosting operation of refrigerant enclosed by the closing operation of a first solenoid valve 30 is weighed by a weighing unit 33 by the closing operation of a second solenoid valve 32. The weighed refrigerant is fed out to an evaporator 4 by the opening operation of the valve 30, and forcibly pressed to a defrosting circuit by the discharging pressure of the hot gas to be discharged from a compressor 1 by the switching operations of a hot gas valve 21 and a three-way switching valve 34. Since the pressing time is normally completed within 20sec, its time is measured in advance to be set to a timer, the valve 34 is switched, after the set time is elapsed, to close an inlet path 35, thereby stopping the introduction of hot gas to the unit 33. After the pump down operation is finished, the defrosting operation can be immediately started.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a refrigeration system, and more particularly, to a refrigeration system that measures refrigerant during defrost and flows it into a defrost circuit to perform defrost operation with a constant amount of refrigerant. .

(Prior Art) Conventionally, a refrigeration system that allows defrost operation with a constant amount of refrigerant by metering refrigerant and flowing it into a defrost circuit is disclosed in Japanese Patent Application Laid-Open No. 59-1977Ef4! 'Known as seen in the gazette.

As shown in Figure 3, this refrigeration system is equipped with a compressor (CP)
A hot gas bypass path (
A hot gas valve (HV) that controls the capacity by controlling the amount of hot gas that bypasses hot gas to
), and on the downstream side of the condenser (CD), 1
A pair of solenoid valves (SV, ) (SV2) and these solenoid valves (SV
A refrigerant measuring section (A) consisting of a meter (T) interposed between I) (SV2) is provided, and a certain amount of refrigerant measured by this meter (A) during defrost operation is measured by the hot gas. The refrigerant flows out into a defrost circuit formed by a bypass path (H), an evaporator (E), and a compressor (CP), and defrosts with a constant amount of refrigerant.

In FIG. 3, (EX) is an expansion valve, and (D) is a flow divider.

(Problems to be Solved by the Invention) However, in the refrigeration system configured as described above, the metering of the refrigerant by the metering section (A) is limited to the solenoid valve (S) on the downstream side.
Perform pump down operation with V, ) closed,
After the pump down is completed, the upstream solenoid valve (SV2) of the metering section (A) is closed, and the refrigerant metered in the metering section (A) flows out into the defrost circuit. After the end of the pump down operation, the upstream solenoid valve (S V l) is opened after a certain period of time (approximately 20 seconds) by a standby timer, and the high and low pressures are balanced. That is, the refrigerant in the metering section (A) flows out into the defrost circuit due to the pressure difference between the high pressure metering section (A) and the low pressure defrost circuit on the evaporator (E) side.

However, as mentioned above, the flow is caused by low pressure balance,
It takes time for the refrigerant to flow out, and since the total part (A) is often located outdoors, there is a problem that it takes a long time especially when the outside air is low. Since the defrost operation is started at , the amount of refrigerant becomes insufficient and the desired defrost cannot be performed, which causes a problem that the defrost time becomes longer.

An object of the present invention is to forcibly flow out the refrigerant measured in the metering section using the discharge pressure of hot gas discharged from the compressor, so that the refrigerant can flow out into the defrost circuit in a short time. The purpose is to solve the above-mentioned conventional problem in which the defrost time becomes longer due to insufficient quantity.

(Means for solving the problems) The present invention provides hot gas discharged from a compressor (1),
a hot gas bypass path (20) that bypasses the condenser (2, 3) and introduces it into the evaporator (4);
) Hot gas valve (21) that bypasses hot gas to
In the refrigeration system, a second valve is provided on the downstream side of the condenser (2, 3) and is closed by a start command from a solenoid valve to confine the refrigerant in a liquid reservoir including the condenser (2, 3). The first opening/closing mechanism (30) is provided, and the first opening/closing mechanism (30) is provided.
), of the refrigerant confined in the liquid reservoir,
A second opening/closing mechanism (32) forming a metering section (33) for refrigerant to be circulated in the defrost circuit is provided, and a hot gas valve is provided downstream of the second opening/closing mechanism (32) in the metering section (33). The measuring section (3) is
The refrigerant measured in step 3) is caused to flow out into the defrost circuit, and an introduction path (33) is provided after the refrigerant flows out.
33) is characterized by being provided with a switching mechanism (34) for switching hot gas introduction to the hot gas bypass path (20).

(Function) During defrosting, the refrigerant measured by the measuring section (33) is
Immediately after the pump-down operation ends, the hot gas is forcibly pushed out by the discharge pressure of the compressor (1) and flows out into the defrost circuit in a short time.

Therefore, there is no shortage of refrigerant from the beginning of the defrost operation, and the amount of refrigerant required for defrost can be secured at the same time as the start of the defrost operation, and the defrost time will not be prolonged due to a shortage of refrigerant.

(Example) What is shown in Fig. 1 is a container refrigeration system, which includes a compressor (1), an air-cooled condenser (2), a water-cooled condenser (3), an evaporator (4), and a temperature sensing section ( The refrigerator is equipped with a temperature-sensitive expansion valve (5) having a temperature-sensitive expansion valve (5a), these devices are connected by a refrigerant pipe (6), and the air inside the refrigerator is cooled by the evaporator (4).

In FIG. 1, (7) is the dryer, (8) is the liquid indicator, (9) is the accumulator, (10) is the fan attached to the evaporator (3), and (11) is the air-cooled condenser (2). ) is a fan attached to the

In the refrigeration system configured as described above, the hot gas discharged from the compressor (1) is transferred to the high pressure gas pipe (6a) through the condensers (2), (3), and the temperature-sensitive expansion valve (5).
) is connected to a bypass hot gas bypass path (20) to the evaporator (4), and its outlet side is connected to a flow divider (12) provided at the inlet side of the evaporator (4), A hot gas valve (21) consisting of a proportional control valve is interposed at the connection portion of the hot gas bypass path (20) to the high pressure gas pipe (6a), and a hot gas valve (21) consisting of a proportional control valve is installed at the connection portion of the hot gas bypass path (20) to the high pressure gas pipe (6a).
), in FIG. 1, the liquid indicator (
8) On the downstream side, on the upstream side of the expansion valve (5), a first opening/closing mechanism (hereinafter simply referred to as a solenoid valve) (30) consisting of a solenoid valve that closes in response to a command to stop freezing or refrigeration operation and a command to start defrost operation. is provided, and a metering tank (31) is provided upstream of the first solenoid valve (30), and the solenoid valve (3
0) enables pump-down operation and confines the refrigerant in the liquid reservoir including the metering tank (31) and the condensers (2) and (3). On the upstream side of the liquid indicator (8) and the metering tank (31) in FIG. The side of the second switch consisting of a solenoid valve (hereinafter simply referred to as a solenoid valve) forming a
32), further comprising a switching mechanism in the middle of the hot gas bypass path (20) between the metering tank (31) and the second solenoid valve (32) in the metering section (33). The hot gas flowing through the high pressure gas pipe (6a) is branched off via the three-way switching valve (34) to the bypass path (34).
20) to connect the introduction path (35).

The three-way switching valve (34) causes the refrigerant measured in the n section (33) to flow out into the defrost circuit using the high pressure of the hot gas introduced from the introduction path (35), and then flows into the introduction path (35). The hot gas is switched to the hot gas bypass path (20).

Further, the defrost circuit is formed by switching the hot gas from the compressor (1) to flow into the panoramic hot gas bypass path (20), and the defrost circuit is formed by switching the hot gas from the compressor (1) to the panoramic hot gas bypass path (20). 21), hot gas bypass path (20), evaporation P5 (4), accumulator (9)
formed by.

Moreover, in the one shown in FIG. 1, a drain pan heater (37) is connected to the hot gas bypass path (20) via a three-way switching valve (36).
7) also forms a part of the defrost circuit.

Further, the hot gas valve (21) adjusts the valve opening degree to the hot gas bypass path (20) from 0 to 100 in proportion to the voltage.
By controlling the amount of hot gas bypassed to the evaporator (4), the capacity can be adjusted to enable freezing and refrigeration operation, and during defrosting operation, the total amount of hot gas is reduced to hot gas. Bypass path (20)
PID control is performed by a controller (40) having a built-in computer.

Further, (5b) is a pressure equalizing pipe of the temperature-sensitive expansion valve (5), and this pressure equalizing pipe (5b) is connected to the low pressure gas pipe ( 6d), during refrigeration operation, the second connecting pipe (5d) is connected to the hot gas bypass path (20), and during refrigeration operation, the superheat degree is controlled by the temperature-sensitive expansion valve (5). In addition, during refrigeration operation, the temperature-sensitive expansion valve (5) is slightly closed to reduce the flow rate of liquid refrigerant to enable economical capacity control.

In addition, although the meter n section (33) is formed using a metering tank (31), this metering tank (31) is not always necessary, and the high pressure liquid pipe (6b) However, it may be formed as a low-pressure liquid pipe (6c), and if the metering tank (31) is not used, a liquid pipe may be used to measure a certain amount of refrigerant.

In Figure 1, (HPS) is a high voltage switch, (HFO
2) is a high pressure control switch, (LPS) is a low pressure switch,
(OPS) is an oil pressure protection switch, and (WPS) is a water pressure switch.

In addition, the command to start the defrost operation is mainly carried out by the air pressure switch (APS) and the defrost timer, and the end of the defrost operation is mainly carried out by the thermostat (TH) that detects the temperature of the low pressure gas pipe (6d). The end of the pump-down operation, which is performed in response to the operation start command, is performed by pressing the low pressure switch (LP).
This is done using S).

Therefore, when performing freezing or refrigeration operation with the above configuration, the controller (40) is operated.

This is done by setting the set temperature using the to-point selector. In refrigeration operation where the set temperature is lower than 15°C, the compressor ( The temperature is adjusted to the set temperature using the start/stop control in 1), and in refrigeration operation at -5℃ or higher,
Based on the supply sensor (SS) installed on the outlet side,
The hot gas valve (21)' is controlled to an opening degree of 0 to 100%, and hot gas is supplied to the evaporator (4) at a flow rate corresponding to the opening degree.
), the temperature is adjusted to the set temperature.

As described above (during freezing or refrigeration operation), if the evaporator (4) is frosted and the air pressure switch (APS) is activated, or the defrost timer is activated and a defrost command is issued, 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, the first electromagnetic valve (30) closes and the hot gas valve (21
) to the hot gas bypass (20), it is controlled to 0% and pump down operation starts.

In this pump-down operation, the liquid refrigerant is trapped in the area from the condenser (2) (3) to the first solenoid valve (30), and as the liquid refrigerant becomes trapped, the low pressure decreases. When the pressure becomes lower than the set value of the low pressure switch (LPS), the low pressure switch (LPS) is turned off and the end of the pump down operation is detected.

At this time, when the low pressure switch (LPS) is turned off, the compressor (1) normally stops, but when the low pressure rises due to the opening operation of the first solenoid valve (30) after metering, which will be explained next, it will restart. Become. However, it is not necessary to stop the compressor (1) at the end of the pump-down operation in the case of defrosting operation, and it is preferable not to stop the compressor (1). When in off-operation, the compressor (1)
Therefore, the system should not be stopped.

When the end of the pump down operation by the low pressure switch (LPS) is detected, the hot gas valve (21) is opened to the hot gas bypass path (20) while the compressor (1) continues to operate. At the same time, the three-way switching valve (34) is also switched to the introduction path (35) side, and the fan (
10) is stopped, and simultaneously with these operations, the second
While the solenoid valve (32) closes, the first solenoid valve (30) opens.

Accordingly, due to the closing operation of the second solenoid valve (32), the amount of refrigerant necessary for the defrost operation among the refrigerant trapped by the closing operation of the first solenoid valve (30) is reduced to the metering section (33).
The refrigerant thus measured is
The opening operation of the first solenoid valve (30) causes the gas to flow out to the evaporator (4), and the switching operation of the hot gas valve (21) and the three-way switching valve (34) causes the gas to be discharged from the compressor (1). The hot gas is forcibly pushed out to the defrost circuit by the discharge pressure of the hot gas.

This extrusion time is usually completed within 20 seconds, so
Measure the time in advance and set it with a timer.
After this set time has elapsed, the three-way switching valve (34) is switched, the introduction passage (35) is closed, and the introduction of hot gas to the metering section (33) is stopped, and after the end of the pump down operation. , defrost operation can be started immediately.

As described above, the pump-down operation can be immediately shifted to the defrost operation without stopping the compressor (1), and the refrigerant measured in the total n section (33) can be transferred to the defrost circuit in a short time. This allows for efficient defrosting without running out of refrigerant even at the beginning of defrosting operation. Therefore, as described above, the transition to defrost operation is quick, and there is no shortage of refrigerant at the beginning of defrost operation, so the defrost time can be shortened accordingly. Although defrost operation can be performed using refrigerant, optimal defrost is always possible regardless of the operating state immediately before the defrost operation.

As described above, as the defrost progresses, the temperature of the low pressure gas pipe (6d) rises, and when this temperature exceeds the set temperature of the thermostat (TH) that detects it, the defrost end signal is output by the operation of the thermostat (TH). Then, defrost operation ends.

Upon completion of this defrost operation, the second on-off valve (3
2) opens and returns to refrigeration operation, open the hot gas valve (2).
1), the opening degree on the hot gas bypass path (20) side is set to 0%, and when returning to refrigeration operation, the opening degree is controlled to be based on the opening degree control from the controller.

In the embodiment described above, the hot gas bypass path (2
Since the drain pan heater (37) is connected to the drain pan heater (37) through the three-way switching valve (36),
) is provided on the leeward side of the evaporator (4), it can be bypassed by switching the three-way switching valve (36), so reheating can be prevented even during freezing or refrigeration operation.

Moreover, although the introduction path (35) is connected to the middle of the hot gas bypass path (20) via the three-way solenoid valve (34), it may be connected to the high pressure gas pipe (6a). In this case, it may be placed upstream or downstream of the hot gas valve (21), or a three-way solenoid valve may be used as the switching mechanism, or the three-way solenoid valve may be provided midway through the introduction path (35).

In addition, in the above configuration, air-cooled and water-cooled condensers (2) and (3) are used together as condensers, but it is also possible to use only a single condenser (2) or (3). , can also be applied to other refrigerators.

(Effects of the Invention) As described above, in the present invention, since the defrost operation is performed by counting a certain amount of refrigerant, the defrost operation can be performed regardless of the operating state immediately before the operation. At the end of defrosting, normal operation can be resumed without abnormally increasing the high pressure of the refrigerant or causing overcurrent to flow through the compressor motor, causing the compressor to become inoperable.

Moreover, the refrigerant measured by the metering section (33) can be forcibly transferred to the defrost circuit by the discharge pressure of the hot gas discharged from the compressor (1), so the transfer can be carried out in a short time and the defrost operation can be started. Defrosting can be performed from the beginning without a shortage of refrigerant, and therefore there is no problem of a longer defrost time due to a shortage of refrigerant.

Furthermore, the measured amount of refrigerant is forcibly transferred using hot gas, and defrosting is performed by flowing the hot gas into a total of n parts, so that while the above-mentioned effects are obtained,
Furthermore, defrost operation can be performed at the same time as pump-down operation ends; in other words, there is no need to wait for the metered refrigerant to be transferred after pump-down operation ends, as is the case with conventional systems, so the transition to defrost operation can be made in a shorter time. This means that the defrost time can be shortened overall.

[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 flowchart of defrost operation, and Fig. 3 is a flowchart of defrost operation.
The figure is a schematic diagram showing a conventional example. (1)... Compressor (2) (3)... Condenser (4)... Evaporator (20)... Hot gas bypass path ( 21)・
...Hobut gas valve (30) ...First opening/closing mechanism (first solenoid valve) (3
2)...Second opening/closing mechanism (second solenoid valve) (33)
...Measuring part (34) ...Switching mechanism (three-way switching valve) (35)
...Introduction route Figure 8 F P

Claims (1)

[Claims] (1) A hot gas bypass path (20) that bypasses the condensers (2, 3) and introduces the hot gas discharged from the compressor (1) into the evaporator (4); In a refrigeration system equipped with a hot gas valve (21) that bypasses hot gas to the condenser (2, 3), the condenser (
A first opening/closing mechanism (30) that confines the refrigerant in a liquid reservoir including 2 and 3) is provided, and a defrost circuit is provided upstream of the first opening/closing mechanism (30) to confine the refrigerant in the liquid reservoir. A second opening/closing mechanism (32) is provided that forms a measuring section (33) for the refrigerant that is circulated through the metering section (33).
A hot gas introduction path (35) is connected to the downstream side of the second opening/closing mechanism (32) in 3), and the hot gas pressure introduced through the introduction path (35) is used to control the measuring section (33).
Let the refrigerant measured in the flow out to the defrost circuit, and
After the refrigerant flows out, the introduction path (33) is connected to the introduction path (33).
) to the hot gas bypass path (2).
1. A refrigeration system characterized by being provided with a switching mechanism (34) for switching to 0).