JPS61159072A - 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, more specifically, a refrigeration system equipped with a capacity control bypass path, which guides hot gas to an evaporator to control the internal temperature of a container or refrigerator, for example. This invention relates to a refrigeration system that controls the temperature to a chilled region higher than -5°C to -6°C, performs defrost operation, and is equipped with a drain pan heater to heat frozen drain in the drain pan and prevent drain clogging.

(Prior Art) This type of refrigeration VT device constructed as follows was previously proposed in Japanese Patent Application No. 150750/1982. That is, this refrigeration system has the ability to supply part or all of the hot gas discharged from the compressor (A) to the evaporator (E) without supplying it to the condenser (C), as shown in FIG. In addition to providing a control bypass path (H) and a drain pan heater (DH) that heats the drain in the drain pan, a three-way solenoid valve (
SV) and the valve opening in proportion to the voltage, e.g. 0 to 100%.
By using a two-way proportional valve (MV) to control the evaporator (E), hot gas is prevented from flowing through the drain pan -9 (DH) when controlling the capacity of the evaporator (E).
The capacity of the evaporator (E) is controlled so that the air cooled in step E) is not heated by the drain pan heater (DH), and the entire amount of the hot gas is directed to the drain pan heater (D'H) during defrosting. The frozen drain that falls into the drain pan from the evaporator (E) is heated and liquefied.

More specifically, the discharge side of the compressor (A) and the condenser (C)
The condenser (
C) and an expansion valve (EV) are connected to each other, and the outlet of this bypass path (H) is connected to the inlet side of the evaporator (E), and the bypass path The two-way proportional valve (MV) is interposed at the junction of (H) with the discharge path (B), and this two-way proportional valve (MV) allows
A part of the hot gas flowing in the discharge path (B) is directly supplied to the evaporator (E) to control the temperature of the air blown from the evaporator (E), or even the temperature inside the refrigerator, to a chilled region; Further, while the entire amount of the hot gas is directly supplied to the evaporator (E) to perform a defrost operation, the bypass path (H
), connect a drain pan heater (DH) that circulates hot gas, and connect this drain pan heater (DH) to the
A drain pan (
(not shown), and a three-way solenoid valve (SV) is installed at the connection between the inlet of the drain pan heater (DH) and the bypass path (H), and during defrost operation, the three-way solenoid valve (SV) Drain pan heater (DH) of solenoid valve (SV)
Fully open the opening and supply the entire amount of hot gas to the drain pan heater (DH) to melt the frozen drain that has fallen into the drain pan without being completely liquefied. Drain IJI ili Ll
17 is constructed to prevent drain clogging.

(Problem to be solved by the invention) However, among the many types of valves used in refrigeration equipment, this prior invention uses a relatively inexpensive three-way solenoid valve, and also uses a three-way solenoid valve that is much more expensive than this solenoid valve. Since a two-way proportional valve is used, there is a problem in that the cost of the entire vtrIL becomes high.

An object of the present invention is to solve the problem of the need to use a very expensive two-way proportional valve in the refrigeration system of the prior invention, and to provide a capacity control bypass path connected to the discharge path. and a defrost bypass passage connected to the discharge passage, and the defrost bypass passage is provided upstream of the capacity control bypass passage, and the cost is much lower than that of the three-way solenoid valve and the two-way proportional valve. By using an inexpensive two-way proportional valve in the evaporator, it is possible to prevent hot gas from flowing to the drain pan heater when controlling the capacity of the evaporator, while reducing costs.

(Means for Solving the Problems) Accordingly, the present invention provides a side path for discharging a portion of the hot gas by a condenser (2) in the hot gas discharge path (9a) connected to the compressor (1). A bypass path (11) for controlling capacity is connected to bypass the evaporator (4), and a drain pan heater (14) is provided below the air outlet side of the evaporator (4) to flow hot gas during defrost operation. In the refrigeration system provided, the capacity control bypass path (11
) is equipped with a two-way proportional valve (1) that adjusts the bypass amount of hot gas.
2), and at the same time, a three-way solenoid valve (13) is installed in the discharge path (9a) upstream of the connection point of the capacity control bypass path (11), and the solenoid valve (13) A defrost bypass path (15) is connected to the discharge path (9a) via the drain pan heater (14), and bypasses the entire amount of the hot gas to the evaporator (4) during defrost operation. be.

(For A'1) Capacity of evaporator (4) 1. When the time comes, fully open the three-way solenoid valve (13) to the defrost bypass passage (15),
The hot gas in the discharge passage (9a) is supplied from the capacity control bypass passage (11) to the evaporator (4) to prevent heating by the drain pan heater (4), and during defrost operation, the three-way 74M valve ( 13) to the defrost bypass path (15) is fully opened, and all of the hot gas in the discharge path (9a) flows into the evaporator (4) to heat the frozen drain in the drain pan (10). This was done to thaw the ice.

(Example) Next, one embodiment of the present invention will be described based on the drawings.

The refrigeration system shown in Figure 1 is a container refrigeration system, in which (1) is a compressor, (2) is an air-cooled condenser, (3) is a water-cooled condenser, and (4) is an evaporator. (5) is a temperature-sensitive expansion valve, (6) is a liquid receiver integrated with an accumulator, (7) is a dryer, and (8) is a liquid indicator. , these devices are connected by refrigerant piping (9), and the evaporator, (4)
) forms a refrigeration cycle that cools the air inside the refrigerator. Further, on the lower side of the evaporator (4), the evaporator (4)
) is provided with a drain pan (10) to catch the drain that falls from the drain.

In the embodiment shown in FIG. 1, the compressor ('
The hot gas discharged from the compressor (1) is transferred to the hot gas discharge path (9a) connecting the discharge side of the compressor (1) and the inlet side of the air-cooled condenser (2). 3), the liquid receiver (6) and the temperature-sensitive expansion valve (5) are bypassed and the evaporator (
4) by connecting the capacity control bypass path (11) leading to
Its outlet is connected to the low pressure liquid pipe (9b) between the expansion valve (5) and the evaporator (4), and this capacity control bypass path (
11), a two-way proportional valve (12) for controlling the bypass amount of hot gas is inserted, and this -force proportional valve (12)
Accordingly, a part of the hot gas in the +1ij discharge path (9a) is supplied to the evaporator (4) via the capacity control bypass path (11), and the capacity of the evaporator (4) is controlled. On the other hand, a three-way solenoid valve (13) is interposed on the upstream side (compressor 1 side) of the connection point (0) of the capacity control bypass path (11) in the discharge path (9a). A drain pan heater (14) disposed below the air outlet side of the evaporator (4) is provided in the discharge path (9a) via a solenoid valve (13), and the entire amount of the hot gas is controlled during defrost operation. A defrost bypass passage (15) to be bypassed is connected to the evaporator (4), and its outlet is connected to the outlet side of the two-way proportional valve (12) in the capacity control bypass passage (11) (evaporator 4 side). ), the three-way solenoid valve (13) supplies the entire amount of hot gas flowing through the discharge path (9a) to the evaporator (4) via the defrosting bypass path (15) to defrost it; During this defrosting operation, the frozen drain that fell into the drain pan (10) in a frozen state without being completely liquefied was thawed by the drain pan heater (14).

In the above configuration, the two-way proportional valve (12) has a first
, equipped with a second port, the valve opening degree can be adjusted from 0 to 10 in proportion to the voltage.
This is an electric valve that can be controlled to 0%, and PID control is performed by a controller (120).

This PID control (Proportional-plus
-1ntegr-al-derlvatlve con
(trol) refers to control in which the control signal is proportional to the sum of the deviation signal, its integral, and its function.

Further, the three-way solenoid valve (13) includes first, second, and third ports (13a), (13b, and 13c), and
The discharge passage (9a) is connected to the ports (13a) and (13b), and the defrost bypass passage (15) is connected to the third port (13c).

Therefore, when controlling the capacity of the evaporator (4), the third port (13c) communicating with the defrost bypass passage (15) of the three-way solenoid valve (13) is closed, and the condenser (2)
The second boat (13b) that communicates is opened and the discharge path (9
a) The hot gas in the capacity control bypass path (11)
The water is supplied to the evaporator (4) via the two-way proportional valve (12), and the capacity of the evaporator (4) is controlled. In this case, the hot gas in the discharge path (9a) is not supplied to the defrost bypass path (15), so the hot gas in the discharge path (9a) is not supplied to the defrost bypass path (15).
) is not heated by the drain pan heater (14). In other words, since there is no need to cool the evaporator (4) in consideration of reheating by the drain pan heater (14), the cooling temperature of the evaporator (4) is set lower than the optimum internal temperature for the object to be cooled. Therefore, it is possible to prevent the temperature of the air blown from the evaporator (4) from dropping too much as in the conventional case, causing the objects to be cooled such as vegetables stored in the refrigerator to lose weight or deteriorate in quality. It can be prevented.

Also, when performing defrost operation, use the three-way solenoid valve (
A second port (13b) communicating with the condenser (2) of 13)
is closed, the third port (13c) communicating with the defrost bypass passage (15) is opened, and the discharge passage (9a) is opened.
The entire amount of hot gas in the defrost bypass passage (1
5), the drain pan heater (14) and the evaporator (
4) and defrost it, and this defrost heats the frozen drain that has fallen from the evaporator (4) into the drain pan (10) to thaw it. In this case, since the entire amount of hot gas is passed through the drain pan heater (14), the time required to thaw the frozen drain in the drain pan (10) can be shortened.

Note that the refrigeration system of the first embodiment shown in FIG. An electromagnetic on-off valve (
21) to enable pump-down operation, and to confine the refrigerant in the liquid reservoir including the liquid receiving parts of the condensers (2) and (3) and the liquid receiver (6), and A defrost circuit, that is, a compressor (1) that performs a defrost operation on a certain amount of refrigerant out of the refrigerant confined in the liquid reservoir.
, three-way solenoid valve (13), defrost bypass path (15)
), an evaporator (4), and a quantitative outflow mechanism (20
) has been established.

This quantitative outflow mechanism (20) includes, for example, the on-off valve (21).
), an electromagnetic on-off valve (22) is installed at a position where a predetermined outflow amount can be obtained, with respect to the intervening position where the on-off valve (21) is installed, of the liquid reservoir that performs a pump-down operation and confines the refrigerant by closing the on-off valve (21). In FIG. 1, the on-off valve (21) is connected to a high-pressure liquid pipe (9) connecting the liquid indicator (8) and the expansion valve (5).
In c), the expansion valve (5) is interposed on the artificial side, and the on-off valve (22) is connected to the high pressure liquid pipe (9c) in 1111.
), the on-off valve (21) of the high pressure liquid pipe (9C) is interposed on the outlet side of the liquid indicator (8).
(22) A certain amount of refrigerant to be confined between the on-off valves (
22) and open the on-off valve (21) to enable outflow.

The amount of refrigerant set by the fixed amount outflow mechanism (20) is determined so that the steady operation performed after the defrost operation is always kept within the operable F-range regardless of the operating state, and the optimal transmission that does not prolong the defrost time. That is to say.

Further, a solenoid valve (energized and closed) is installed in the middle of the suction gas pipe (9d) connecting the artificial side of the compressor (1) and the liquid receiver (6).
26) and a capillary tube (27) are connected in parallel.

The solenoid valve (26) is configured to return the suction gas refrigerant to the compressor (1) via the capillary tube (27) by closing the solenoid valve (26), thereby reducing the amount of refrigerant circulation; The reason for reducing the circulating IO 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. As a result, the work capacity of the compressor (1) decreases due to the decrease in the amount of circulation, and the high pressure and the current value of the compressor motor decrease, causing the operating speed to decrease.
Therefore, m can be expanded.

The solenoid valve (26) detects the suction temperature of the evaporator (4), closes when the suction temperature exceeds a certain value to reduce the circulation amount, and opens when the suction temperature falls below a certain value. It has become.

In the above configuration, the two-way proportional valve (12) is controlled by the output signal from the controller (120) and the defrost operation start command, and the opening/closing valve (12) is controlled by the defrost operation start command. 21) is closed to perform pump-down operation, and the end of this pump-down operation and the start of defrost operation are mainly controlled using the low pressure switch (83L).

The command to start the defrost operation mainly uses an air pressure switch and a defrost timer whose set time is, for example, 12 hours. In this case, the air pressure switch has priority over the defrost timer, and when the air pressure switch is activated,
This is done by resetting the defrost timer.

The end of the defrost operation can be completed, for example, by the evaporator (4).
Two thermostats with different set temperatures are attached to the low pressure gas pipe (9e) on the outlet side of the low pressure gas pipe (9e).
This is done by detecting the temperature in step 9e).

In the figure, (F,) is a fan attached to the evaporator (4), (F,) is a fan attached to the air-cooled condenser (2),
(E33H) is the high pressure switch, (83CL) is the high pressure side control switch, (83QL) is the oil pressure maintenance switch, (!i switch 1.
(63W) is a water pressure switch.

Next, the effect when the quantitative outflow mechanism (20) is provided will be explained.

First, during freezing or refrigeration operation, when a defrost operation start command is issued, the on-off valve (21) closes and pump-down operation begins.

In this pump-down operation, the liquid refrigerant is transferred to the condenser (2) (
3) and the liquid receiving part of the liquid receiver (6) and the on-off valve (21)
At the same time, 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 (83L), the low pressure The switch (83L) is turned off, the compressor (1) stops, and the pump-down operation ends.

The three-way solenoid valve (13) has a third port (130).
) is switched to be fully open, the indoor fan motor (MF, ) is stopped, and at the same time, the on-off valve (22) is closed and the +1'1 on-off valve (21) is opened.

As described above, the on-off valve (22) is closed, and the on-off valve (22) is closed.
When 1) opens, a certain amount of liquid refrigerant trapped in the high-pressure liquid pipe (9C) between these on-off valves (21) and (22) will gasify and flow out because there is a difference between high and low pressures. It is.

The reason why this liquid refrigerant gasifies and flows out to the evaporator (4) side is that the volume of the defrost circuit is considerably larger than the volume of the refrigerant stored in the constant ffi outflow mechanism (20), and the pump down Due to operation, the refrigerant on the outlet side of the M generator (4) is in a superheated state, so the expansion valve (5) must be open, and immediately after opening the on-off valve (21), the liquid refrigerant will boil due to pressure drop. For this reason, the evaporator (
4) Even if a part of the liquid refrigerant remains, the amount of refrigerant originally stored in the quantitative outflow mechanism (20) is small, and the part of the liquid refrigerant flows into the high-pressure liquid pipe (
θC) This is because the amount of heat taken from the liquid volume stored by itself and the outside temperature through the high-pressure liquid pipe (9c) can be sufficient for evaporation.

This outflow causes the low pressure to rise and the low pressure switch (
63L), the low pressure switch (83L) is turned on, the compressor (1) is started, and a certain amount of the refrigerant circulates through the defrost circuit, and the defrost bypass path (15 ), defrosting can be performed by hot gas flowing into the evaporator (4).

Since this defrost operation is performed using a fixed amount of refrigerant set by the quantitative outflow mechanism (20), optimal defrost is always possible regardless of the operating state immediately before the defrost operation.

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 of the liquid receiver (6), so the liquid back up to the compressor (1) is doesn't happen.

When the defrost is completed as described above, the thermostat with the lower set temperature of the two thermostats provided on the outlet side of the evaporator (4) is activated, so the defrost is completed and the on-off valve (21) (22) opens and returns to freezing operation, or during refrigeration operation, the two-way proportional valve (12) shifts to opening control by the controller (120) and returns to steady operation.

Furthermore, when returning to normal operation after this defrost operation is completed,
The ambient temperature of the evaporator (4) is constant compared to steady operation, but since the refrigerant circulation amount during the defrost operation is controlled to a constant amount, the high pressure becomes abnormally high and the high pressure switch (83h) The overcurrent relay will not operate,
Steady operation can always be carried out reliably, but 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 can be reduced, but since this is a very rare case, in the embodiment shown in FIG.
6) and a capillary tube (27), the solenoid valve (26) is closed by detecting the temperature of the blown air, high or low pressure, or outside temperature, and the refrigerant is circulated through the capillary tube (27). It is made to reduce the amount,
Therefore, depending on operating conditions in which the outside temperature is abnormally high and the high pressure rises, the electromagnetic valve (26) is closed to enable operation with a reduced amount of refrigerant circulation, thereby expanding the operable range.

The refrigeration system described above is applied to a container refrigeration system in which a drain pan (13) is provided on the air outlet side of the evaporator (4), but it can also be applied to other refrigerators.

In addition, as the condenser, an air-cooled condenser (2) and a water-cooled condenser (3) were used together, but a single condenser (2) or (
Only 3) is acceptable.

(Effects of the Invention) As described above, the present invention provides the ability to connect to the hot gas discharge path (9a) and bypass a portion of the hot gas to the evaporator (4) by bypassing the condenser (2). Control bypass path (
11) is equipped with a two-way proportional valve (12) for adjusting the bypass amount of hot gas, while a three-way electromagnetic valve is installed upstream of the connection point of the capacity control bypass path (11) in the discharge path (9a). A drain pan heater (14) is connected to the discharge passage (9a) via the solenoid valve (13).
), and bypasses the entire amount of hot gas to the evaporator (4) during defrost operation! (15) is connected by +1, so when the capacity of the evaporator (4) is controlled, the hot gas flows to the drain pan heater (14), and the air cooled by the evaporator (4) is transferred to the drain pan heater (14). Although it is possible to avoid heating, the two-way proportional valve (12) as well as the three-way solenoid valve (13) are very inexpensive compared to two-way proportional valves. This allows the overall cost to be reduced and the product to be provided at a low price.

4. Drawing ITi! IL Description FIG. 1 is a refrigerant piping system diagram showing one embodiment of the refrigeration system of the present invention, and FIG. 2 is a refrigerant piping system diagram of a conventional example.

(1)...Compressor (2)...Condenser (4)...Evaporator (9a)...Discharge path (11)... ... Capacity control bypass path (12)
... Two-way proportional valve (13) ... Three-way solenoid valve (14) ... Drain pan heater (15) ...
...Defrost bypass path Figure 1

Claims (1)

[Claims] (1) Hot gas discharge path (9) connected to compressor (1)
A capacity control bypass passage (11) is connected to a) for bypassing a part of the hot gas through the condenser (2) and bypassing the evaporator (4), and the air in the evaporator (4) is In a refrigeration system that is provided with a drain pan heater (14) disposed below the outlet side to allow hot gas to flow during defrost operation, a two-way proportional valve (12) is provided in the capacity control bypass path (11) to adjust the bypass amount of hot gas. ), and a three-way solenoid valve (1
3), and the discharge path (
9a) is equipped with a drain pan heater (14), and during defrost operation, the entire amount of the hot gas is transferred to the evaporator (4).
) A refrigeration system characterized in that a defrost bypass passage (15) is connected to the defrost bypass passage (15).