JPH0571855B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to a refrigeration system used in a marine container or the like, specifically, to a hot gas discharged from a compressor.
The present invention relates to a refrigeration system equipped with a hot gas bypass circuit that bypasses a condenser and leads hot gas to an evaporator, and a hot gas valve that leads hot gas to the bypass circuit.

(Prior art) Conventionally, as this type of refrigeration device, for example,
As shown in Publication No. 197764, the hot gas discharged from the compressor is bypassed to the evaporator side to adjust the capacity, and the temperature inside the container or freezer is lowered to, for example, -5°C to -6°C. At the same time, when frosting occurs, a certain amount of refrigerant is measured, and the measured refrigerant is supplied to the defrost circuit to control the total amount of hot gas discharged from the compressor. Introducing the entire amount of hot gas discharged from the compressor into the evaporator side using a defrost operation that removes frost adhering to the evaporator using the retained heat of the hot gas, or using the same defrost circuit. It is known that the temperature inside the refrigerator can be raised from -20°C to 0°C, that is, a heat-up operation can be performed.

(Problem to be Solved by the Invention) By the way, in the above system, when performing the defrost operation and heat-up operation in which the entire amount of hot gas discharged from the compressor is supplied to the evaporator side using the defrost circuit, a The current fan continues to operate normally. This is because during defrost operation at high outside air temperatures, the temperature of the hot gas discharged from the compressor becomes high, and when the hot gas is forced into the evaporator all at once, the frost on the evaporator is melted into ice blocks. It falls into the drain pan,
There are problems such as the connection with the drain hose becoming clogged or the high pressure rising excessively and activating the protection device.In order to avoid this, the fan attached to the condenser is driven. This is because hot gas is actively leaked from the hot gas valve to the condenser side to adjust the amount of refrigerant.

However, if the fan attached to the condenser continues to be driven as usual, when the same defrost circuit is used for heat-up operation, only the amount leaked from the hot gas valve will be supplied to the evaporator. There is a problem that the amount of hot gas decreases, the heating capacity of the evaporator decreases, and the heat-up time takes a long time.

The purpose of the present invention is to reduce the air volume of the condenser fan compared to the air volume during defrost operation when performing heat-up operation by bypassing the entire amount of hot gas discharged from the compressor to the evaporator, as in defrost operation. The present invention is intended to improve the heat-up capability during heat-up operation while eliminating the above-mentioned problems during defrost operation.

(Means for Solving the Problems) Accordingly, the present invention provides a hot gas bypass circuit 8 for guiding the hot gas discharged from the compressor 1 to the evaporator 5 bypassing the condenser 2, and a hot gas bypass circuit 8 for guiding the hot gas discharged from the compressor 1 to the evaporator 5, In the refrigeration system, which is equipped with a hot gas valve 7 that leads to the hot gas bypass circuit 8 and enables a defrost operation and a heat-up operation in which the entire amount of the hot gas is guided to the hot gas bypass circuit 8 to heat the evaporator 5, during the defrost operation,
a detection means A for operating the fan F of the condenser 2 and detecting heat-up operation; and an air volume for making the air volume of the fan F of the condenser 2 smaller during the heat-up operation than the air volume of the fan F during the defrost operation. It is equipped with an adjustment means B.

(Function) By operating the fan F of the condenser 2 during defrost operation, defrost can be performed with an appropriate amount of refrigerant even when the outside air is high, and defrost operation can be performed in a protected area where the protection device does not operate. At the same time, it can also prevent ice blocks from falling.
Furthermore, when performing heat-up operation using the defrost circuit, the air volume of the fan F of the condenser 2 is made smaller than during defrost operation, so the amount of refrigerant leaking from the hot gas valve 7 can be minimized, which increases the heat-up accordingly. It can improve your abilities.

(Example) What is shown in FIG. 1 is a refrigeration system installed in a sea container, etc.
The air-cooled condenser 21 is equipped with a condenser fan F.
and a water-cooled condenser 22 having a water pipe 3 are connected, and an expansion mechanism 4, an evaporator 5, and an accumulator 6 are sequentially connected to the condenser 2 via a refrigerant pipe 10 to form a refrigeration cycle. It is.
Note that the fan F is the first and second condenser fan F.
2-1 and F2-2, and the evaporator 5 is attached with internal fans F1-1 and F1-2.

Further, between the discharge gas pipe 11 and the inlet of the evaporator 5, there is a hot gas bypass circuit 8 for guiding the hot gas discharged from the compressor 1 to the evaporator 5 via a hot gas valve 7 consisting of a three-way proportional valve. established,
The opening degree of the hot gas valve 7 with respect to the bypass circuit 8 is adjusted, and the amount of hot gas guided from the bypass circuit 8 to the evaporator 5 is adjusted to enable chilled operation, and the hot gas is not bypassed to the bypass circuit 8. The entire discharged gas is condensed and expanded without any heating and introduced into the evaporator 5, for example at -5°C to -6°C.
This enables refrigeration operation in the frozen range below ℃.

Further, a metering tank 12 sandwiched between first and second solenoid valves SV-1 and SV-2 is installed downstream of the water-cooled condenser 22, and the first solenoid valve SV-1 is closed. Confining liquid refrigerant on the upstream side of the valve SV-1,
Thereafter, the second solenoid valve SV-2 is closed to meter a certain amount of refrigerant, and the first solenoid valve SV-1 is opened to allow a certain amount of refrigerant to flow out into the defrost circuit. Defrost operation and heat-up operation are performed using a certain amount of refrigerant. That is, the hot gas valve 7
Mainly uses an electric three-way valve, and the valve opening degree to the hot gas bypass circuit 8 can be controlled from 0 to 100% in proportion to the voltage, thereby controlling the amount of hot gas bypass to the evaporator 5. At the same time as adjusting the capacity, a proportional control valve is used that opens to 100% during defrost operation, and the electric part 7M of the hot gas valve 7 PID-controls the valve opening by a controller 20, which will be described later.

The controller 20 is equipped with a central processing unit CPU as shown in FIG. 3, and on its input side there is a set point selector CPS for setting a predetermined temperature range in which the internal temperature should be maintained, and on the suction side of the evaporator 5. A return sensor RS, which detects the temperature of the return air from inside the refrigerator, that is, the temperature of the intake air, and a supply sensor SS, which is arranged on the outlet side and detects the temperature of the outlet air, are connected. The air pressure switch APS detects frost based on the pressure difference on the outlet side and outputs a defrost start command, and the defrost timer DT measures the passage of a certain amount of time after the defrost operation is completed and outputs a defrost start command. Furthermore, a detection means A for detecting heat-up operation, which will be described later, and an outside air temperature detector TH for detecting outside air temperature are connected.
is connected to.

And, on the output side of the controller 20,
a motor MC of the compressor 1 and the first and second motors;
Condenser fan F2-1, F2-2 motor MF2
-1, MF2-2, and the motor MF1- of the evaporator fans F1-1, F1-2.
1. An electric part 7M of the hot gas valve 7 which is connected to the MF1-2 and further controls the amount of hot gas bypassed to the hot gas bypass circuit 8, and the electric part 7M of the hot gas valve 7, which measures a certain amount of refrigerant and causes it to flow out to the defrost circuit. The first and second solenoid valves SV-1 and SV-2 are connected.

Then, depending on the set temperature set by the set point selector CPS, the central processing unit CPU of the controller 20 selectively uses the return sensor (RS) and the supply sensor SS to control the refrigeration operation below -5°C. In this case, the temperature inside the refrigerator is adjusted by starting and stopping the compressor 1 based on the return sensor RS, and in the case of chilled operation at 5° C. or higher, the hot gas valve 7 is adjusted based on the supply sensor SS. The temperature inside the refrigerator is controlled by controlling the opening of the compressor 1 and controlling the start/stop of the compressor 1.

The defrost operation is started under the control of the controller 20 when the evaporator 5 is frosted and the air pressure switch APS is activated, or when the defrost timer DT is activated and a command to start the defrost operation is issued. Then, the hot gas valve 7 and the first and second solenoid valves SV-1 and SV-2 are operated to meter a certain amount of refrigerant and guide it to the hot gas bypass circuit 8.

Therefore, in the refrigeration system configured as described above, the present invention operates the first and second condenser fans F2-1 and F2-2 during the defrost operation, and also uses the detection means A for detecting the heat-up operation. When heat-up operation is detected, the air volume of the first and second condenser fans F2-1 and F2-2 is changed to the air volume of the fan F2 during defrost operation.
-1, F2-2 - An air volume adjusting means B is provided to make the air volume smaller than that of F2-2.

In the embodiment shown in FIG. 2, the detection means A for detecting the heat-up operation uses an operation switch for the heat-up operation, and a thermometer HTh (hereinafter referred to as In addition, as the air volume adjustment means B, two first and second condenser fans F2-
1, F2-2, the first condenser fan F2-1
The air volume is adjusted by stopping the air flow.

The compressor relay 8 shown in FIG.
8CM and said first and second condenser fan F2-
1. A control circuit in which first and second condenser fan relays 88CF1 and 88CF2 for controlling the start and stop of motors MF2-1 and MF2-2 of F2-2 are connected in parallel, and this control circuit is provided with the aforementioned control circuit. Compares the detection results of the heat-up thermometer HTh, the return sensor RS and supply sensor SS, and the set point selector CPS, and turns on when the temperature inside the refrigerator becomes higher than the temperature set by the set point selector CPS. A parallel circuit is connected in series between the operating thermo switch FTh and the defrost switch DSW, which is turned on when a defrost start command is output from either the air pressure switch APS or the defrost timer DT. Connect the reverse contact HTh-1 of the up thermometer HTh to the first condenser fan F2-
1st condenser fan relay 88CF1 to control
It was inserted in series with the circuit.

Further, in the control circuit shown in FIG. 2, the outside air temperature detector TH is connected in series to the second condenser fan relay 88CF2 that controls the second condenser fan F2-2, so that the outside air temperature is If it is lower than the set value, it is turned off and the second condenser fan F2-
I am trying to stop 2.

In the above configuration, when the defrost switch DSW turns on and performs defrost operation, the first solenoid valve SV-1 is closed to perform pump-down operation, and then the second solenoid valve SV-2 is closed. After metering, the hot gas valve 7 is switched and at the same time the first solenoid valve SV-1 is opened to supply the metered amount of refrigerant to the defrost circuit.

During this defrost operation, the first and second condenser fans F2-1 and F2-2 are operated except when the outside air temperature is higher than the set value. During operation, the refrigerant circulating in the defrost circuit actively leaks from the hot gas valve 7 to the air-cooled condenser 21 side, so that defrost operation can be performed with an appropriate amount of refrigerant even when the outside air temperature is high. It can be done. Also, as in the defrost operation, a certain amount of refrigerant, which is measured by opening and closing the first and second solenoid valves SV-1 and SV-2, is circulated from the hot gas bypass circuit 8 to the evaporator 5 and the compressor 1. When a heat-up operation is performed, the reverse contact HTh-1 is turned off in conjunction with the ON operation of the heat-up thermometer HTh, and the operation of the first condenser fan F2-1 is stopped. Therefore, leakage of refrigerant from the hot gas valve 7 is reduced, allowing heat-up operation without reducing the predetermined amount of refrigerant, and thus improving heat-up capability.

Note that when the outside air temperature is low, the second condenser fan F2-2 is stopped, so the heat-up operation is performed with the condenser fan F having no air volume.

Therefore, the first
By stopping the condenser fan F2-1 during heat-up operation, the first and second solenoid valves are
Even if a certain amount of refrigerant measured by opening and closing SV-1 and SV-2 is guided to the hot gas bypass circuit 8 for heat-up operation in the same manner as defrost operation, there is no leakage from the hot gas valve 7, and the heat-up capacity is maintained. Moreover, since the first fan F2-1 is always in operation during defrost operation, the certain amount of refrigerant is actively leaked from the hot gas valve 7, and excess refrigerant is prevented. The defrost operation can be reliably carried out within the protected area even when the outside air is high without introducing it to the condenser 5.

In this embodiment, the air-cooled condenser 21 is provided with first and second condenser fans F2-1 and F2-2,
The air volume is adjusted by turning one of the fans on and off, but the method of adjusting the air volume is not limited to this.Many fans can be individually controlled to start and stop, and the desired number of fans can be adjusted. The air volume may be adjusted step by step by starting and stopping the fan, or a fan may be used that can continuously adjust the air volume by changing the rotational speed of the motor, for example.

Furthermore, although the above embodiments are applied to a refrigerant device loaded in a sea container, the present invention can also be applied to other refrigerators. Moreover, as the condenser 2, although the air-cooled condenser 21 and the water-cooled condenser 22 are used together, the air-cooled condenser 21 alone may be used.

(Effects of the Invention) According to the refrigeration system according to the present invention, while defrosting can be performed well when the outside air is high, the entire amount of hot gas discharged from the compressor 1 is guided to the hot gas bypass circuit 8 in the same manner as in the defrosting operation. During the heat-up operation to heat the evaporator 5, the air volume of the fan F of the condenser 2 is made smaller than that during defrost, so that when the temperature rises inside the container, etc., the hot gas flows to the condenser 2 side. Leakage can be reduced, the amount of hot gas that should originally be supplied in its entirety to the evaporator 5 can be prevented from decreasing, and the heat-up capacity can be improved.

[Brief explanation of drawings]

FIG. 1 is a refrigerant piping system diagram of a refrigeration system according to the present invention, FIG. 2 is an external motor control circuit diagram, and FIG. 3 is a block diagram for explaining the operation of the refrigeration system. 1... Compressor, 2... Condenser, 5... Evaporator,
8...Hot gas bypass circuit, A...Heat-up operation detection means, B...Air volume adjustment means, F2-
1...First condenser fan, F2-2...Second condenser fan.

Claims (1)

[Claims] 1 comprises a hot gas bypass circuit 8 that guides the hot gas discharged from the compressor 1 to the evaporator 5 bypassing the condenser 2, and a hot gas valve 7 that guides the hot gas to the hot gas bypass circuit 8, In a refrigeration system that enables a defrost operation and a heat-up operation in which hot gas is guided to the hot gas bypass circuit 8 to heat the evaporator 5, a fan F of the condenser 2 is operated during the defrost operation, and a heat-up operation is detected. A refrigeration system characterized in that it is equipped with a detecting means A for detecting the airflow, and an air volume adjusting means B for making the air volume of the fan F of the condenser 2 smaller during the heat-up operation than the air volume of the fan F during the defrost operation.