JPH0537172Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device for preventing an abnormal rise in high pressure during defrosting operation of a refrigeration device such as a refrigerator, chiller, water heater, or air conditioner.

(Prior Art) A refrigerant circuit of a conventional refrigerator is shown in FIG. 3, and its electric control circuit is shown in FIG. 4.

In Fig. 3, during cooling operation, the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 passes through the four-way valve 2 and enters the condenser 3 installed outside the refrigerator, as shown by the solid line arrow, where it enters the condenser. By dissipating heat to the outside air blown by the No. 3 fan 11, the refrigerant condenses and liquefies, becoming a high-temperature, high-pressure liquid refrigerant. Next, this liquid refrigerant passes through a dryer 4 and a check valve 5 and enters a throttle device 6 such as an expansion valve, where it is throttled and expands adiabatically to become a low-temperature, low-pressure gas-liquid two-phase. Next, this gas-liquid two-phase refrigerant enters the evaporator 7 installed in the refrigerator, where it is passed through a blower 12 for the evaporator 7.
By absorbing heat from the air blown into the refrigerator, it evaporates and becomes a low-temperature, low-pressure refrigerant gas.
It is sucked into the compressor 1 through the four-way valve 2 and the accumulator 8.

During defrosting operation, the four-way valve 2 is switched, and the refrigerant flows in the opposite direction to that during the cooling operation, as shown by the broken line arrow, to the compressor 1, four-way valve 2, evaporator 7, check valve 9, and capillary tube. etc. throttle device 10, condenser 3, four-way valve 2, accumulator 8
in this order and then returns to the compressor 1. In this process, the high temperature and high pressure refrigerant gas discharged from the compressor 1 flows through the evaporator 7 and
The frost adhering to the outer surface of the machine will melt and be removed. During this defrosting operation, the blower 11 for the condenser 3 is operated, but the blower 12 for the evaporator 7 is stopped in order to prevent the temperature inside the refrigerator from rising.

In FIG. 4, when the temperature control thermostat 27 is closed during cooling operation, the electromagnetic contactor 20 for the compressor 1 is energized, so its normally open contact 20a is closed and the drive motor of the compressor 1 is closed. 21 is energized, and at the same time, the driving electric motor 22 of the blower 11 for the condenser 3 is energized. At this time, the relay 26 is demagnetized and its normally closed contact 26b is closed, so
The driving electric motor 23 of the blower 12 for the evaporator 7 is energized.

The inside of the refrigerator is cooled by the cooling operation, and when the temperature inside the refrigerator reaches the set temperature of the temperature control thermostat 27, the temperature control thermostat 27 is opened, and accordingly, the electricity to the electric motors 21 and 22 is cut off. Therefore, the compressor 1 and condenser 3 blower 11 are stopped. In addition, during cooling operation, reversal prevention relay 3
0 is activated and its normally closed contact 30b is opened, or when the overcurrent relay 31 is activated, the relay 25 is demagnetized and its normally open contact 25a is activated.
is opened, cutting off all power to this control circuit.

The defrosting timer 29 is constantly excited, and its normally open contact 29a closes at regular intervals (for example, once every three hours) to start defrosting operation. In conjunction with this, the relay 26 is energized, its normally open contact 26a is closed, and its normally closed contact 26b is opened. Although the normally closed contact 29a of the defrost timer 29 opens after a few seconds, the relay 26 is continuously energized by its self-holding circuit. When the normally open contact 26a of the relay 26 is closed, the coil 24 for the four-way valve 2 and the electromagnetic contactor 20 for the compressor 1 are closed.
Since the four-way valve 2 is switched to the defrosting state, the blower 1 for the compressor 1 and condenser 3 is turned on.
1 rotates, but the normally closed contact 26b of the relay 26 is opened, thereby cutting off the power to the drive motor 23 of the blower 12 for the evaporator 7.

When the temperature of the evaporator 7 rises due to the end of defrosting and reaches the operating temperature of the defrosting end detection thermostat 28, this defrosting end detection thermostat 28
is opened, and along with this, the relay 26 is demagnetized, so its normally open contact 26a is opened, and its normally closed contact 2
6b is closed and the state returns to the state during cooling operation.

(Problems to be solved by the invention) In the conventional refrigeration system described above, the blower 11 for the condenser 3 is operated during defrosting operation, but the blower 12 for the evaporator 7 prevents the temperature inside the refrigerator from rising. be suspended for. As a result, while a large amount of frost adheres to the outer surface of the evaporator 7, a large amount of latent heat is radiated in the evaporator 7 due to melting of the frost. Capillary tube 1
The refrigerant pressure (approximately equal to the refrigerant condensation pressure until it reaches 0) does not rise above the specified value, but after the frost adhering to the outer surface of the evaporator 7 melts and its amount decreases or is removed. The temperature of the side plate of the evaporator 7 to which the defrosting completion detection thermostat 28 is attached is determined by the defrosting completion detection thermostat 28.
Until the operating temperature is reached, the amount of heat absorbed by the condenser 3 is much larger than the amount of heat radiated by the evaporator 7, so the high pressure suddenly rises above the specified value and the equipment in the refrigerant circuit is damaged. There was a problem with it being damaged.

(Means for Solving the Problems) The present invention has been proposed to address the above problems, and its gist is that during cooling operation, the refrigerant flows through the compressor, condenser, throttling device, etc. In a refrigeration system in which the evaporator is circulated in this order and the refrigerant is circulated in the opposite direction to the above during defrosting operation and the evaporator blower is stopped, the pressure switch operates by detecting high pressure during defrosting operation; At least two fixed throttling devices with different flow resistances are provided in parallel on the refrigerant inlet side during defrosting operation of the condenser, and the fixed throttling device with small flow resistance is installed in series. A device for preventing an abnormal rise in high pressure during defrosting operation of a refrigeration system, characterized in that the pressure switch is equipped with an electromagnetic valve that closes in response to a signal when the pressure switch detects a preset operating value. be.

(Function) Since the present invention has the above configuration,
During defrosting operation, if the high pressure does not reach the operating value of the pressure switch, the solenoid valve is open and a large amount of refrigerant flows into the condenser through at least two fixed throttle devices in parallel. It absorbs a large amount of heat from the condenser. Then, when the high pressure reaches the operating value of the pressure switch, the solenoid valve is closed by the signal from this point on, and a small amount of refrigerant flows into the condenser through the fixed throttle device with greater flow resistance.
The amount of heat absorbed in the condenser is reduced, preventing an abnormal rise in high pressure.

(Embodiment) An embodiment of the present invention is shown in FIGS. 1 and 2, in which FIG. 1 is a refrigerant circuit diagram and FIG. 2 is an electric control circuit diagram. As shown in FIG. 1, a first capillary tube 14 and a second capillary tube 15 are arranged in parallel with each other on the refrigerant inlet side of the condenser 3 in parallel with the dryer 4 and the check valve 5. connected so that The flow resistance of the first capillary tube 14 is the same as that of the second capillary tube 1.
5, and a solenoid valve 16 is installed in series with the inlet side of this first capillary tube 14.
is interposed. And the four-way valve 2 and the evaporator 7
A pressure switch 13 is attached to the refrigerant pipe connecting the refrigerant pipes, through which high-pressure refrigerant flows during defrosting operation and through which low-pressure refrigerant flows during cooling operation, which operates by detecting the pressure of the refrigerant flowing therein. . The operating value of this pressure switch 13 is slightly higher than the high pressure when the frost adhering to the evaporator 7 has finished melting (for example, when R502 is used as the refrigerant, 10 to 15
Kg/cm ² G) is set and is sufficiently higher than the low pressure during cooling operation, so it does not operate during cooling operation. The pressure switch 13 is connected to a flow path through which high-pressure refrigerant flows during defrosting operation, that is, from the discharge port of the compressor 1 to the capillary tubes 14 and 15.
However, if it is installed between the compressor 1 and the four-way valve 2, it may be activated only during defrosting operation using an electric signal or the like.

As shown in FIG. 2, the excitation coil 33 of the electromagnetic valve 16 is connected in parallel with the coil 24 of the four-way valve 2, and the contact 32 of the pressure switch 13 is connected in series with this excitation coil 33. The other configurations are the same as the conventional one shown in FIGS. 3 and 4,
Corresponding members are given the same reference numerals.

During the cooling operation, the refrigerant discharged from the compressor 1 flows through the four-way valve 2, the condenser 3, the dryer 4, the check valve 5, the expansion valve 6, the evaporator 7, as shown by the solid arrow in FIG. It returns to the compressor 1 through the four-way valve 2 and the accumulator 8 in this order. During this cooling operation,
Since the refrigerant pressure at the inlet and outlet of the first and second capillary tubes 14 and 15 is approximately the same, no refrigerant flows through the first and second capillary tubes 14 and 15.

During defrosting operation, if the solenoid valve 16 is open, the refrigerant circulates as shown by the broken line arrow in FIG. As it flows through, the frost adhering to the outer surface is melted and condensed into liquid, producing high temperature and
It becomes a high-pressure refrigerant liquid. Most of this refrigerant liquid passes through the check valve 9 and the solenoid valve 16 and flows into the first capillary tube 14, and at the same time the remainder flows into the second capillary tube 15.
As it flows through the capillary tubes 14 and 15, it is constricted and expands adiabatically, becoming a gas-liquid two-phase at low temperature and low pressure. Next, this gas-liquid two-phase refrigerant is evaporated in the condenser 3 to become a low-temperature, low-pressure refrigerant gas, which returns to the compressor 1 via the four-way valve 2 and the accumulator 8.

During this time, the drive motor 22 of the condenser 3 blower 11 is energized, but the drive motor 23 of the evaporator 7 blower 12 is stopped to prevent the temperature inside the refrigerator from rising.

As a result, the high pressure changes as shown in FIG.
The increase is relatively small because heat is absorbed by the temperature, but it increases rapidly when the amount of frost decreases or when the frost has finished melting. When this high pressure reaches the operating value of the pressure switch 13, its contact 32 opens to cut off the current supply to the excitation coil 33 of the solenoid valve 16. Then, since the refrigerant liquid passes only through the second capillary tube 15 having a large flow path resistance, the amount of refrigerant flowing into the condenser 3 decreases, and the amount of heat absorbed from the outside air in the condenser 3 decreases.

Thus, from then on, the amount of heat absorbed in the condenser 3 decreases, so the rise in high pressure becomes much smaller than in the conventional case, as shown by the broken line.

Although the first and second capillary tubes 14 and 15 are used in the above embodiment,
Instead, an expansion valve or other throttling device may be used, and the number of throttling devices may be three or more. Furthermore, although the above embodiment is an example in which the present invention is applied to a refrigerator, the present invention is also applicable to defrosting frost attached to a heat exchanger on the heat source side of an air conditioner, water heater, etc. that uses air as a heat source. Of course, it can be applied.

(Effect of the invention) In the present invention, during defrosting operation, the refrigerant circulates in the order of the compressor, evaporator, throttling device, and condenser, and the evaporation blower stops, and the high pressure reaches the operating value of the pressure switch. If not, the solenoid valve is open, and a large amount of refrigerant flows into the condenser through at least two fixed throttle devices in parallel, absorbing a large amount of heat from the condenser and causing it to adhere to the evaporator. It can quickly disperse frost.

Then, when the high pressure gradually increases and the pressure switch detects the preset operating value, the solenoid valve is closed in response to the signal from now on, allowing a small amount of refrigerant to pass through the fixed throttle device with greater flow resistance. flows into the condenser, the amount of heat absorbed in the condenser is reduced, and an abnormal rise in high pressure can be prevented.

In this way, damage to equipment within the refrigerant circuit can be reliably prevented with an extremely simple and inexpensive structure.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention,
FIG. 1 is a refrigerant circuit diagram, and FIG. 2 is an electrical control circuit diagram. 3 and 4 show an example of a conventional refrigerator, with FIG. 3 being a refrigerant circuit diagram and FIG. 4 being an electrical control circuit diagram. FIG. 5 is a diagram showing temporal changes in high pressure. Compressor...1, condenser...3, throttling device...1
4, 15, Evaporator...7, Solenoid valve...16, Pressure switch...13.

Claims (1)

[Scope of utility model registration request] In a refrigeration system in which the refrigerant circulates through the compressor, condenser, throttle device, and evaporator in this order during cooling operation, and the refrigerant circulates in the opposite direction to the above during defrosting operation and the evaporator blower stops, during defrosting operation a pressure switch that is activated by detecting high pressure in the condenser, at least two fixed throttle devices that are provided in parallel on the refrigerant inlet side and have different flow resistances when the condenser is in defrosting operation, and that the flow resistance is small. A refrigeration system characterized by comprising an electromagnetic valve that is installed in series with a fixed throttle device and that closes upon receiving a signal when the pressure switch detects a preset operating value during defrosting operation. Device to prevent abnormal rise in high pressure during defrosting operation.