JPS63183359A - 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 Field of Application) The present invention relates to a refrigeration system, more specifically, a refrigeration system that is equipped with a hot gas bypass passage, bypasses hot gas to the evaporator to adjust the capacity, and cools the refrigerant circulating during frosting. The present invention relates to a refrigeration system that performs defrost operation by circulating the entire amount to the evaporator.

(Prior art) Conventionally, hot gas is bypassed to the evaporator to adjust the capacity, and the internal temperature of a container or refrigerator is set to -5, for example.
From the frozen region below ℃~-6℃, -5℃~-6℃
A refrigeration system capable of controlling the temperature in a chilled region at a higher temperature is already known as disclosed in Japanese Patent Application Laid-open No. 197784/1984.

As shown in Figure 6, this refrigeration system connects the discharge gas pipe () (G) of the compressor (CP) to the hot gas valve (HGV), which is an electric three-way valve that allows the valve opening to be adjusted. , the condenser (CN) and the expansion valve (EV) are bypassed, and the evaporator (EV
In addition to providing a hot gas bypass path (HGP) leading to A), a high pressure liquid pipe (HL) k: a pair of solenoid valves (SVt) (
These solenoid valves (SVI) (SV2) are installed
) A liquid reservoir (LH) is provided between
The hot gas is bypassed to the evaporator (EVA) by adjusting the valve opening to adjust the capacity, and at the time of frosting, the solenoid valve (SV,) is closed to perform pump-down operation, and then Close the solenoid valve (SV2) and open the solenoid valve (SV,) to open the liquid reservoir (LH).
A predetermined amount of refrigerant trapped in the refrigerant is discharged, and this predetermined amount of refrigerant is circulated through the hot gas bypass path (HGP) to perform defrosting.

In addition, (R) in FIG. 6 is a liquid receiver.

(Problem to be Solved by the Invention) However, the above-described refrigeration system does not operate during defrost operation, regardless of the operating state of the refrigeration system immediately before that, in other words, during defrost operation and chilled operation, the capacity is adjusted to the temperature in the frozen region. Regardless of whether it is a chilled operation where the capacity is adjusted to the temperature of the area or an operation where the capacity is controlled according to the load, defrosting is performed using a preset constant amount of refrigerant. When under load, the amount of refrigerant circulated is too small, resulting in a long defrost time and a problem in that residual frost is likely to occur.

To solve this problem, you can increase the preset amount of refrigerant, but if you increase the amount, the amount of refrigerant circulated will be too large during high loads with high outside temperatures, and the high pressure will rise, resulting in a high pressure cut, and the defrost operation will be interrupted. In any case, in containers such as marine containers that are used under conditions with large changes in outside air temperature, it is necessary to set the amount of refrigerant to the optimal value for these load conditions. It cannot be set, and the above-mentioned problem occurs in either case.

As described above, the present invention has the advantage of the conventional metering operation in which a constant amount of refrigerant is metered and circulated during defrosting, that is, defrosting operation can be performed with a constant amount of refrigerant regardless of the operation immediately before defrosting operation. Therefore, in contrast to full-volume operation in which the entire volume is circulated and defrosted, normal operation can always be returned to without the high pressure rising abnormally or excessive flow flowing into the compressor and causing the compressor to become inoperable at the end of defrosting. To make it possible to always shorten the defrost time and perform defrosting without residual frost, regardless of the outside temperature during defrosting operation, while taking advantage of the advantages, and also to be able to perform defrosting without being unable to operate due to high pressure cut during defrosting. The purpose is to

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention uses metering operation and full-volume operation in combination, and performs defrosting in full-volume operation regardless of the outside temperature. This system is designed to shift to a reduction operation in which the total circulation is reduced due to an increase in gas pressure, and is equipped with an on-off valve (10) that stores refrigerant in the liquid reservoir including the condenser (2) by pump-down operation, while defrosting operation is also possible. Pressure detection means for detecting the hot gas pressure at the time, and flow n control that stores a part of the refrigerant in the liquid reservoir to reduce the amount of refrigerant circulation during defrost operation when the hot gas pressure approaches the high pressure setting pressure. He provided the means.

(Function) When performing defrost operation based on the defrost command, defrost is first performed using the entire amount of circulating refrigerant, and this full amount operation can shorten the defrost time, and during defrost operation using the entire amount of circulating refrigerant, the hot gas pressure is When the pressure reaches a high pressure setting that stops the compressor (1), a part of the refrigerant is stored in the liquid reservoir to reduce the amount of bypass to the evaporator (5),
The defrost operation can be performed without the compressor (1) stopping due to the high pressure cut and making the defrost operation impossible.

(Example) The example shown in FIG. 1 is a container refrigeration system,
It is equipped with a compressor (1), a condenser (2), a liquid receiver (3), a temperature-sensitive expansion valve (4), an evaporator (5), and a discharge gas pipe (
6) and the condenser (2) and the temperature-sensitive expansion valve (4) via a hot gas valve (7) between the inlet of the evaporator (5) and the inlet of the evaporator (5).
A hot gas bypass path (8) is provided to bypass the
In addition, the high pressure liquid pipe (9) on the downstream side of the condenser (2)
) has 1. An electromagnetic on-off valve (hereinafter referred to as electromagnetic valve) (10) that closes in response to a command to stop operation and a command to start defrost operation is provided to enable pump-down operation, and the condenser (2) and liquid receiver ( 3) The refrigerant can be confined in the liquid reservoir.

The condenser (2) is an air-cooled or water-cooled condenser, or a combination of an air-cooled condenser and a water-cooled condenser, and when an air-cooled condenser is used as shown in FIG. (11) is added. In addition, the evaporator (
5) is an air evaporator equipped with a fan (12). Further, on the discharge side of the compressor (1), a compressor (
1) High-pressure pressure detector (
HPS) and a low pressure pressure detector (L
PS).

Further, the hot gas valve (7) mainly controls the valve opening degree to the hot gas bypass path (8) to 0% in proportion to the voltage.
An electric three-way valve that can be controlled to 100% is used, and the hot gas bypass amount to the evaporator (5) is P
ID control is performed to control the capacity, and at the same time, the entire amount of refrigerant circulated during defrosting is transferred to the hot gas bypass path (8).
We are trying to distribute it to.

Therefore, in the embodiment shown in FIG. 1, in the refrigeration system configured as described above, a pressure detector (DPS) is provided in the hot gas bypass path (8) to detect the hot gas pressure during the defrost operation. , the hot gas pressure during defrost operation is determined by the high pressure pressure detector (H
A defrost operation is performed in which a portion of the refrigerant is stored in the liquid reservoir and the hot gas is bypassed to the evaporator (5) when the pressure reaches a high pressure setting (e.g. 18 kg) near the high pressure setting (e.g. 20 kg) set in PS). In other words, a flow rate control means is provided to reduce the amount of bypass transmission, that is, the amount of refrigerant circulated.

More specifically, the command to start the defrost operation is issued mainly by using an air pressure switch (APS) together with a defrost timer and manual switch (3D) whose set time is, for example, 12 hours. The defrost timer is reset by the action of this switch (APS) with priority given to the defrost operation, and the defrost operation is terminated using, for example, a thermistor (Th) that detects the low pressure gas temperature.

Further, the flow rate control means is configured by controlling the hot gas valve (7) based on the detection result from the pressure detector (DPS) using the controller (20) shown in FIG. be.

The controller (20) shown in FIG. 2 is a compressor motor (MC) in the refrigeration system shown in FIG. The motor (M) of the fan (11) attached to (2)
F2), and also controls the electric part (20M) of the hot gas valve (7) and the electromagnetic valve (10), and is connected to a power source via a transformer.

Therefore, on the input device side of the controller (20),
A return sensor (R8) detects the intake air temperature of the evaporator (5) and controls the start/stop of the compressor (1) during frozen operation, and a hot gas valve (R8) detects the blowout air temperature and controls the start/stop of the compressor (1) during frozen operation. ), a supply sensor (SS) and a set point selector (PS) that control the opening from 0 to 100%, an air pressure switch (APS) that instructs the start of defrost operation, and the thermistor (Th) that detects the end of defrost operation. ) is connected, and the electromagnetic relay (88C) of the compressor motor (MC) is connected to the output device side.
, the electromagnetic relays (88EF) (88CF) of each of the fan motors (MF, ) (MF2) and the hot gas valve (7).
), the solenoid relay (2OR) of the solenoid valve (10), and the hot gas pressure detection circuit and manual switch (3D
) are connected to a manual defrost start circuit.

The electromagnetic relay (88C) (88CF) that controls the start/stop of the fan motor (MF2) of the fan (11) attached to the compression fan (MC) and the condenser (2) is connected to the high-pressure pressure detector ( HPS) and overcurrent relay (51c)
, are connected in parallel to the series circuit of the thermoswitch (49c), and a fan thermoswitch (49CF) is interposed in the circuit of the electromagnetic relay (8BCF).

In the above configuration, the air temperature can be adjusted using the set point selector (PS) of the controller (20).
) and the return sensor (R8
) or the supply sensor (S ) opening control is performed.

When the frozen or chilled operation is performed as described above, the evaporator (5) is frosted and the air pressure switches (AP, S) are activated, and the defrost timer is activated to issue a command to start the defrost operation. When the button appears or the manual switch (3D) is operated, the following defrost operation is performed.

This defrost operation will be explained according to the flowchart shown in FIG. 3. First, when a command to start the defrost operation is issued, the electric part (20M) of the hot gas valve (7) operates, and the hot gas valve (7) Hot gas bypass (
Fully open for 8).

At this time, the flowchart shows that the hot gas valve (7) is fully opened immediately after the defrost operation start command, but when the hot gas valve (7) is switched to fully open, the discharge gas pipe (6) is blocked. As a result, the high pressure may temporarily rise and the high pressure sensor (IPS) may operate, but in this case, the high pressure sensor (HPS) may cause the compressor (1) to If it is stopped, it will take some time until the next restart, so it is preferable to avoid this stop and temporarily force the compressor (1) to stop.

Then, by fully opening the hot gas valve (7), the entire amount of hot gas flows into the hot gas bypass path (8), and defrosting is started with the full amount of circulation.

Note that the solenoid valve (10) is closed by the command to start the defrost operation, but the hot gas valve (7)
After the switch to fully open, the switch closes after a certain time delay (within 1 minute). This is to prevent refrigerant from accumulating on the condenser (2) side at the start of defrost operation, and to ensure that defrost operation can always be performed with the full amount.

Therefore, a timer count is started at the same time as the hot gas valve (7) is fully opened, and the solenoid valve (10) is closed after the timer count-up.

As described above, since the defrost operation is performed using the entire amount, the defrost can be performed in a short time.

During this defrost operation, if the outside air temperature is high, the high pressure increases, and in this case, the pressure detector (DPS) is activated.

When this pressure detector (DPS) is activated, the hot gas valve (7) of the controller (20) is fully closed, the defrost operation is temporarily interrupted, and the pump down operation is switched. In this case, the condenser fan (1
1) may be in a stopped state, but by operating it, it can be stored as a liquid refrigerant during pump-down operation.

By this pump-down operation, the refrigerant is stored in the above-mentioned liquid reservoir, and the refrigerant port for storing the refrigerant in this liquid reservoir is controlled by a timer for a certain period of time (
After 1 minute (usually about 1 minute), the hot gas valve (7) is fully opened again and the defrost operation is restarted.

The defrost operation after restarting is performed using the remaining amount of refrigerant accumulated in the liquid reservoir, that is, the amount of refrigerant circulated is smaller than that during the defrost operation with the total Q described above, and the pressure is increased by the amount that the refrigerant circulation is reduced. The pressure is also reduced.

Then, when the high pressure increases again during this reduction operation and the pressure detector (DPS) is activated, the above control is repeated.
Furthermore, the amount of circulation can be reduced, and the high pressure detection "isi (HP S ) will not be activated and the compressor (1) will be stopped and the defrost operation will not be disabled until the end of the defrost.

When the defrost operation is completed in this way, the end is detected by the action of the thermistor (Th),
The hot gas valve (7) returns to steady operation control by the return sensor (R3) or supply sensor (SS), and the defrost operation ends.

In the embodiment described above, the hot gas valve (7) is switched from fully open to fully open by the operation of the pressure detector (DPS).
The defrost operation was interrupted for 1 hour and a part of the refrigerant was stored in the liquid reservoir under timer control by pump-down operation. A hot gas relief passage (13) is provided between the middle and the outlet of the hot gas valve (7) leading to the condenser (2) and the condenser (2), and this relief passage (
13) is opened by the ON operation of the pressure detector (DPS),
Hot gas outflow valve (1) consisting of a solenoid valve that closes with off operation
4) may be interposed.

In this case, the high pressure increases and the pressure detection W(, DP
S) turns on, the hot gas outflow valve (14)
is opened and a portion of the hot gas flowing through the hot gas bypass path (8) to the evaporator (5) flows to the condenser and is stored in the liquid reservoir, and the defrost operation continues. At the same time, the amount of circulation can be controlled to decrease.

In this case, the condenser fan (11), which was stopped at the beginning of the defrost operation, is operated to liquefy the refrigerant in the condenser (2), and the defrost operation according to this embodiment is shown in FIG. It becomes like a flowchart.

This flowchart is basically the same as the one shown in Figure 3, but after the hot gas valve (7) is fully opened with the defrost operation start command, it remains fully open until the defrost operation is completed. , instead, the pressure sensor (
The hot gas outflow valve (14) is opened by the ON operation of the pressure sensor (DPS), and the condenser fan (11) is operated, and the hot gas outflow valve (14) is closed by the OFF operation of the pressure detector (DPS). The difference is that the condenser fan (11) is stopped.

In this embodiment, the above-mentioned reverse rotation stop of the condenser fan (11) is not necessarily required.

Furthermore, the embodiments described above are based on the pressure detector (DPS).
However, in the second embodiment shown in FIG. 4, the hot gas outflow valve (14)
Instead, a high pressure control valve may be interposed in the relief passage (13). In this case, the high pressure control valve allows pressure detection means to be used in combination.

(Effects of the Invention) As described above, the present invention provides an on-off valve (10) for storing refrigerant in a liquid reservoir section including the condenser (2), on the downstream side of the θ compression type (2).
On the other hand, there is a pressure detection means for detecting the hot gas pressure during defrost operation, and when the hot gas pressure approaches the high pressure setting pressure, a part of the refrigerant is stored in the liquid reservoir and the amount of refrigerant circulation during defrost operation is adjusted. By providing a flow rate control means for reducing the amount of defrost, it is possible to perform a defrost operation by circulating the entire amount, regardless of the operating state immediately before the defrost operation, and regardless of the outside air temperature during the defrost operation. In addition to shortening defrost time, when high pressure increases during defrost operation, some refrigerant is stored in the liquid reservoir and the hot gas bypass path (8)
The amount of refrigerant circulated during defrost operation can be reduced through the compressor (1) due to the high pressure increase.
) will not stop and defrost operation will become impossible, making it possible to expand the operating range of full-volume hot gas defrost and improve its reliability.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant piping system diagram showing one embodiment of the present invention;
The figure is a schematic electrical circuit diagram, Figure 3 is a flowchart diagram,
FIG. 4 is a refrigerant piping system diagram showing another embodiment, FIG. 5 is a flowchart thereof, and FIG. 6 is a refrigerant piping system diagram showing a conventional example. (1)...Compressor (2)...Condenser (5)...Evaporator (7)...Hot gas valve (8)... ...Hot gas bypass path (10)...
...Opening/closing valve

Claims (1)

[Claims] (1) A hot gas bypass path (8) that bypasses the condenser (2) and bypasses the hot gas discharged from the compressor (1) to the evaporator (5), and the evaporator (5). a hot gas valve (7) that performs a defrost operation by controlling a hot gas bypass amount of the hot gas bypass passage (8) to adjust the capacity and circulating the entire amount of refrigerant circulating during frosting from the hot gas bypass path (8) to the evaporator (5); ), and on the downstream side of the condenser (2), an on-off valve (10
), and a pressure detection means for detecting the hot gas pressure during defrost operation, and when the hot gas pressure approaches the high pressure setting pressure, a part of the refrigerant is stored in the liquid reservoir to circulate the refrigerant during defrost operation. A refrigeration system characterized by comprising a flow control means for reducing the amount of water.