JP2001324248A - Defrosting controller for freezing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely achieve drain by preventing drain on a drain pan from freezing. SOLUTION: Since a drain pan is heated by a heating means for a predetermined time before a predetermined time of defrosting control, drain water produced owing to the defrosting control is prevented from being frozen even though the drain water is dropped on the drain pan, so that drain is securely achieved. Further, according to the present invention also after the defrosting control is completed, heating control for the drain pan is continued for a predetermined time, so that drain water remaining on the drain pan and drain water dropping even after the defrosting control can be prevented from being frozen to improve drain property of the drain water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus mounted on a refrigerating vehicle or the like, which is provided with a defrosting means for preventing the formation of frost on an evaporator, and which is dropped on a drain pan for receiving drain water generated during defrosting. The present invention relates to a defrost control device for a refrigeration system having a heating means for preventing freezing of drain water.

[0002]

2. Description of the Related Art A conventional defrost control device of a refrigerating apparatus energizes a drain pan heater for heating a drain pan disposed below the evaporator at the same time as the defrost control of an evaporator of the refrigerating apparatus, and the drain water dripped from the evaporator. Some are designed to prevent freezing.

[0003]

However, in the above conventional example, the drain pan heater is energized at the same time as the defrost control, and the drain pan heater is energized at the same time as the defrost control is stopped. Due to insufficient heating, the drain water that has dropped on the surface of the drain pan re-freezes, or ice particles that have fallen from the evaporator adhere to the drain pan, resulting in insufficient drain water drainage. Further, since the power supply to the heater is stopped simultaneously with the stop of the defrost control, a problem occurs that the drain water dripped from the evaporator is re-frozen by the cool air blown out. There is a problem that the collected ice grows and the drain hole is closed.

[0004] Therefore, an object of the present invention is to provide a defrost control device of a refrigeration system that can prevent drain water from freezing on a drain pan and reliably drain water.

[0005]

Therefore, the present invention comprises at least a compressor, a condenser, an expansion device and an evaporator, and comprises a hot gas passage connecting the discharge port of the compressor and the evaporator, and a hot gas passage. A refrigeration cycle comprising: an opening / closing means for opening and closing; a drain pan provided below the evaporator, for receiving and draining drain water dropped from the evaporator; and a heating means for heating the drain pan, A frost state detection unit that detects the presence or absence of frost on the evaporator, and when frost formation on the evaporator is detected by the frost state detection unit, opens and closes the opening / closing unit to remove the high-temperature and high-pressure refrigerant immediately after discharging the compressor. The evaporator is allowed to flow into the evaporator, and the evaporator Defrost control means for closing the opening / closing means when it is detected that the frost formation has been eliminated, and operating the heating means for a predetermined time prior to the operation of the defrost control means, A drain pan heating control means for operating the heating means for a predetermined time after the operation is completed is provided.

Thus, according to the present invention, since the drain pan is heated by the heating means for a predetermined time before the defrost control is performed, even if the drain water generated by the defrost control is dropped on the drain pan, it freezes. Since there is no drainage, it is possible to reliably drain water. Further, according to the present invention, even after the defrost control is completed, the heating control of the drain pan is continued for a predetermined time, so that it is possible to prevent freezing of drain water remaining in the drain pan and drain water dripped even after the defrost control. ,
The drainage of drain water can be improved. As a result, the above problem can be solved.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

A refrigeration system 1 shown in FIG.
1, condenser 22, expansion valve 23 and evaporator 24
Has a refrigeration cycle 2 configured at least. The refrigeration cycle 2 is provided with a hot gas passage 26 that communicates between the discharge side of the compressor 21 and the expansion valve 23 and the evaporator 24. The hot gas passage 26 is provided on the hot gas passage 26. The electromagnetic valve 25 which opens and closes is provided. Incidentally, 27
Is a condenser fan that supplies air to the condenser 22
(CONDFAN).

The evaporator 24 of the refrigeration cycle 2
Is an air suction port 36 that opens into a space to be frozen (not shown).
Is provided in a duct 31 having an air discharge port 37 opened to the space to be air-conditioned, and in the duct 3, air is sucked from the air suction port 36 and the evaporator 24.
Is provided with an evaporator fan (EVAFAN) 32 that supplies the air to the air.

Below the evaporator 24,
A drain pan 33 for receiving drain water generated when the evaporator 24 is defrosted is provided, and the drain pan 33 is provided with a drain hole 34 for draining the received drain water. A drain pan heater 50 for heating the drain pan 33 is provided below the drain pan 33.
The heater is preferably an electrically controllable one such as a ceramic heater or a thermoelectric element such as a Peltier element. In the present embodiment, this heater is used. May be circulated, and a heating cycle may be supplied to a heat source (an engine, an exhaust pipe, or the like when the internal combustion engine is used as a drive source) in another place by forming a brine cycle. .

The refrigerating apparatus 1 having the above-described configuration includes at least a central processing unit (CPU) (not shown), a random access memory (RAM), a read-only memory (ROM), an input / output port (I / O), and the like. An input unit having a control unit 4 having a microcomputer and receiving signals from temperature sensors 41 and 42 for detecting at least an evaporator temperature Te and a room temperature Tr in a frozen space (not shown) including a multiplexer, an A / D converter, and the like. 5, and further, a setting signal and the like from the operation panel 6 are input, processed in the control unit 4 according to a predetermined program, and converted into control signals. This control signal is output from the capacitor fan 2
7, a driving device 8 for the evaporator fan 32, a driving device 7 for the heater 50, an electromagnetic valve 25, an electromagnetic clutch 28 for driving the compressor 21, and the like.

In normal control, when the electromagnetic clutch 28 is turned on and the compressor 21 starts operating, the compressor 21 sucks the refrigerant, compresses it, and discharges it to the condenser 22. In the condenser 22, the high-temperature and high-pressure refrigerant compressed by the compressor 21 releases heat to the air supplied by the condenser fan 27, is cooled and condensed, and becomes a high-pressure liquid-phase refrigerant. Then, the refrigerant passes through the expansion valve 23 and expands to become a low-pressure low-temperature refrigerant.
4, the air supplied by the evaporator fan 32 absorbs the heat of the air, evaporates, and is sucked by the compressor 21. As a result, a refrigeration cycle in which the heat absorbed by the evaporator 24 is dissipated by the condenser 22 is formed, and the air cooled by the evaporator 24 blows out to the space to be frozen to freeze the space to be frozen.

Further, the defrost according to the present invention (defrost)
The control is shown in the flowcharts of FIG. 2 and FIG.
The routine is executed by a jump command or an interruption by a timer periodically from the refrigeration control normally executed as described above.

As shown in FIG. 2, in the defrost control started from step 100, it is first determined in step 110 whether or not the room temperature Tr of the space to be frozen is equal to or lower than a predetermined temperature α. Whether the fan (EVAFAN) 32 is driven or not,
Further, in step 130, the room temperature T of the space to be frozen
It is determined whether or not the temperature change ΔTr of r is equal to or more than + β. In the above determination, when the temperature of the space to be frozen is equal to or lower than the predetermined temperature α and the indoor temperature Tr is increased despite the fact that the evaporator fan 32 is driven, frost is formed on the evaporator 24. Since it can be determined that the blowing of the cold air has become impossible, the defrost control of step 140 and subsequent steps is executed. Otherwise, the process proceeds to step 250 via the connector B to avoid the defrost control. And proceed to another control routine.

In addition to the above determinations in steps 110 to 130, it is also possible to detect the blowing temperature of the evaporator 32 and detect frost formation on the evaporator 24 by increasing the blowing temperature. It is also possible to detect the air flow and determine that frost has formed on the evaporator 24 due to the decrease in the blown air flow.

In the above determination, when it is determined that frost is formed on the evaporator 24, as shown in FIG.
At 0, the drain pan heater (DH) 50 is operated. Then, in step 150, the operation of the drain pan heater 50 is held for a predetermined time t1, and then, in steps 160, 170, and 180, the evaporator fan (EVAFAN) 32 is stopped (OFF) and the condenser fan (CONDFAN) 27 is stopped ( OFF), the solenoid valve (HGV) 25 is opened (ON), the hot gas passage 26 is opened, and defrost control is executed.

As described above, the evaporator fan 32,
Since the drain pan heater 50 is operated prior to the defrost control executed by stopping the condenser fan 27 and opening the hot gas passage 26, the drain pan temperature T
dp, as shown in FIG. 4, after a lapse of a predetermined time t1 (FIG.
(From tp1 to tp2) from about -21 ° C to -5 ° C. After elapse of the predetermined time t1, at tp2, the above-described defrost control is executed, so that the high-temperature refrigerant flowing through the evaporator 24 causes the evaporator 2
The drain pan temperature Tdp rises due to the drain water dropped and the frost attached to 4 melts and the heat from the evaporator 33. In this case, as shown by the one-dot chain line in FIG. 4, the temperature rise of the drain pan temperature Tdp is larger than in the case where the drain pan heater 50 and the defrost control are simultaneously executed, and the freezing temperature of the drain water (about 0 ° C. or lower) is reduced. Since the liquid escapes early, it is possible to prevent the drain water from freezing.

The above defrost control is performed in step 190.
Is continued until the evaporator temperature Te becomes equal to or higher than the predetermined temperature γ. When the evaporator temperature Te becomes equal to or higher than the predetermined temperature γ (tp3), it is determined that the frost adhering to the evaporator has been removed, and Steps 200 to 200 are performed. 2
At 20, the hot gas passage 26 is closed, the driving of the evaporator fan 32 and the condenser fan 27 is resumed, the defrost control is released, and the control shifts to the normal control.
If it is determined in Step 230 that the predetermined time t2 has elapsed (tp4), Step 2
40 and the operation of the drain pan heater 50 is stopped (DH
OFF), and the process proceeds from step 250 to another control routine.

As described above, since the operation of the drain pan heater 50 is maintained for the predetermined time t2 even after the defrost control is completed, as shown in FIG.
Since the time during which dp becomes the freezing temperature (approximately 0 ° C. or less) can be delayed, it is possible to prevent freezing of the drain water remaining in the drain pan 33 and the dripping of the drain water even after the end of the defrost control.

[0020]

As described above, according to the present invention, since the drain pan heater is operated prior to the defrost control, the temperature of the drain pan heater can be raised to a high temperature in a short time. Even if there are some ice particles on the top, it can be thawed reliably. In addition, since the drain pan heater is operated for a predetermined time after the end of the defrost control, it is possible to prevent freezing of the drain water after the end of the defrost control, and to prevent freezing of the drain water dripped after the end of the defrost control. It can improve drainage.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a refrigeration apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a part of defrost control according to the embodiment of the present invention.

FIG. 3 is a flowchart showing the remaining part of the defrost control according to the embodiment of the present invention.

FIG. 4 is a timing chart of defrost control according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus 2 Refrigeration cycle 21 Compressor 22 Condenser 23 Expansion valve 24 Evaporator 25 Solenoid valve 26 Hot gas passage 27 Condenser fan 31 Duct 32 Evaporator fan 33 Drain pan 34 Drain hole 50 Drain pan heater

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3L046 AA02 AA03 AA04 AA07 BA01 CA03 FB01 FB03 GA04 GB03 JA03 LA15 LA34 MA01 MA03 MA04 MA05 3L048 AA02 AA03 AA06 BA01 CA02 CB03 CD01 FA01 GA01 GA02 GA03

Claims (1)

[Claims] At least a compressor, a condenser,
A refrigeration cycle comprising an expansion device and an evaporator, comprising a hot gas passage connecting the discharge port of the compressor and the evaporator, and an opening / closing means for opening and closing the hot gas passage, and a refrigeration cycle provided below the evaporator, In a refrigeration system having a drain pan that receives and drains drain water dropped from an evaporator, and a heating unit that heats the drain pan, a frost formation state detection unit that detects the presence or absence of frost on the evaporator; When frost formation on the evaporator is detected by the detection means, the opening / closing means is opened to flow a high-temperature and high-pressure refrigerant immediately after discharge of the compressor to the evaporator,
Defrost control means for closing the opening / closing means when the frost state detection means detects that frost on the evaporator has been eliminated; and operating the heating means a predetermined time prior to the operation of the defrost control means And a drain pan heating control means for operating the heating means for a predetermined time after the operation of the defrost control means is completed.