JPS5852458Y2 - Defrost device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a defrosting device for a refrigeration system, and more specifically, it is a new defrosting device that can reduce lining costs during normal refrigeration operation while ensuring sufficient heat from hot gas frost. Regarding structure.

In a refrigeration system equipped with a water-cooled condenser, if frost forms on the evaporator, it is undesirable because it causes a decrease in cooling capacity and liquid return, so it is necessary to provide a defrosting device.

As shown in FIG. 4, the conventional defrosting device is provided with an automatic water supply valve 23 in the cooling water line of the water-cooled condenser 5.

This is to prevent the defrost ability from decreasing due to the drop in discharge pressure and the temperature of the discharge gas when a defrost command is issued and the discharge gas flows into the hot gas bypass pipe 9. The water supply valve 23 senses condensation pressure,
It functions to keep the condensing pressure constant by always adjusting the amount of cooling water to a slightly lower level.

In this case, even during normal refrigeration operation, the water-cooled condenser 5 will be operated at a high condensing temperature (pressure) of, for example, 15 kgcm2, leading to a decrease in the coefficient of performance of the compressor and causing damage to the lining during normal refrigeration operation. The disadvantage of increasing costs was unavoidable.

In response to this fact, the present invention was devised to eliminate the fundamental defects of conventional devices,
During normal refrigeration operation, the amount of cooling water is ensured to ensure efficient operation, while during defrosting, to secure the heat source, the amount of cooling water is reduced or zeroed immediately before defrosting operation, and after reaching the predetermined condensing temperature. The present invention is characterized in that it starts defrosting.

The specific content of the present invention will be explained below in detail with reference to the accompanying drawings. Fig. 1 shows a refrigeration system according to an embodiment of the present invention, which includes a compressor 4, a water-cooled condenser 5, a dryer 10, and an electromagnetic device for liquid refrigerant. The valve 1, pressure reducer 6, evaporator 7 and accumulator 8 form a known refrigeration cycle.

In this refrigeration cycle, a hot gas bypass pipe 9 is provided to bypass the water-cooled condenser 5 and the pressure reducer 6, and the solenoid valve 2 is interposed in the bypass pipe 9.

On the other hand, the water-cooled condenser 5 has a pressure detector 9 that closes when the refrigerant pressure reaches a predetermined pressure or higher, for example, 15 kg/cm2.
In addition, a solenoid valve 3 capable of suppressing water flow to the condenser 5 is interposed in the cooling water line.

Note that this solenoid valve 3 may be provided in a pipeline that bypasses the condenser 5.

The refrigeration system having the above-described structure performs refrigeration operation and defrost operation by the control circuit shown in FIG. 2, and this control circuit includes an electromagnetic switch 11. An electromagnetic switch 12 for starting and stopping the evaporator fan motor 7M, a timer 13 for defrosting the solenoids Is, 2S, and 3S of each electromagnetic valve 1, 2.3, for example, a program timer, and each auxiliary relay 14, 15, 16
, 17, 18, the pressure switch 19, an internal thermostat 20 that detects the temperature inside the refrigerator, a defrost detector 2 that detects the end of defrosting, a thermostat or a pressure detector, a compressor protection relay 22, and an operation switch. It is equipped with SW.

The program timer 13 closes the contact 13a for about 15 minutes every 24 hours by driving the motor 13M to issue a periodic defrosting command.
When a is closed, the relay 18 is energized to demagnetize the solenoid 3S and close the solenoid valve 3, stopping or extremely reducing the flow of cooling water, and opening the contact 13a to fully open the solenoid valve 3. It is designed to allow water to flow in a fixed amount.

Further, when the relay 16 is energized by closing the contact 13a and the pressure switch 19, the solenoid 2S is energized to open the solenoid valve 2 and send hot gas to the evaporator 7 via the bypass pipe 9. When defrosting is started, the solenoid valve 3 is closed and the defrosting operation is stopped by opening the contact 13a.

On the other hand, when the defrost detector 21 is activated, the relay 17 is energized even if the defrost command is issued from the program timer 13, so that the relay 16 is deenergized and the solenoid valve 2 is closed, and the relay 18 is deenergized, the solenoid valve 3 is opened, and the defrosting operation is stopped.

Next, to explain the operating mode of the refrigeration system, contact 14C
, the relay 15 is energized via the relay 22, and the contact 15
It is self-held by a-1, and the contact 15 a
-2,15a-a is closed.

On the other hand, the solenoid 3S is energized and the solenoid valve 3 is fully opened.

Next, when the operation switch Sw is switched from the stop notch to the blowing notch, the relay 14 is energized and self-held by the contact 14a, and the coil 12S is energized to drive the evaporator fan motor 7M.

Next, when the operation switch Sw is switched to the temperature control notch, if the temperature inside the refrigerator is high, the coil 11S is energized and the compressor motor 1M is driven, and the solenoid valve 1 is opened and refrigeration operation begins. The timer 13 starts timing.

In this way, refrigeration operation begins with sufficient cooling water available.

When the contact 13a of the timer 13 closes after 24 hours, the relay 18 is energized, the solenoid valve 3 is closed, and the compressor motor 1M is forcibly driven by the contact 18H.

When the solenoid valve 3 is closed, the flow of cooling water is stopped and the temperature of the condenser 5 rises. At the same time, the pressure inside the condenser 5 also rises and the pressure switch 19 is closed, so the relay 16 is closed. When the contact 16a is closed, the solenoid valve 2 is opened, and when the contact 16b is opened, the coil 12S is deenergized and the fan motor 7M is stopped.

Therefore, rapid defrosting is performed by the hot gas whose heat is secured due to the temperature rise.

This frosting is canceled by issuing a cancellation command to the timer 13 or a cancellation command to the defrost detector 21, whichever comes first.

When using timer 13, contact 13a opens → relay 1
6, 18 De-energize → close solenoid valve 2, open solenoid valve 3, and return to normal refrigeration operation.

On the other hand, when using the defrost detector 21, the switch 21 is closed → the relay 17 is energized → the contact 17C is switched → the relay 16
, 18 deenergization → closing of solenoid valve 2 and opening of solenoid valve 3, the normal refrigeration operation is similarly restored.

In any case, when the cooling water starts flowing, the condenser 5
The pressure sensor 19 returns to its open state due to the pressure drop.

In this way, during refrigeration operation, an abundant supply of cooling water ensures efficient operation, while in the case of defrosting, the operation is started by the temperature rise of the hot gas, so defrosting Defrosting can be completed in a short period of time as sufficient heat is secured.

It goes without saying that the solenoid valve 3 installed in the cooling water line can be a general-purpose one that fully opens and closes, but as shown in FIG. and the valve seat portion 3a interposed in the passage between the outflow port 3C and the outflow port 3C.
By drilling a small hole 3d in the valve and using a solenoid valve with a structure that allows the small hole 3d to be used as a bypass passage for a portion of the cooling water when the valve is closed, a small amount of cooling can be achieved even when the valve is closed. It is possible to circulate water, and is extremely effective in preventing the condenser 5 from rising in abnormal temperature during defrosting operation.
This solenoid valve 3 is a preferred embodiment.

As explained above, in order to secure a heat source for defrosting operation, the defrosting device of the present invention reduces the flow rate of cooling water in the water-cooled condenser 5 immediately before starting operation, and reaches a predetermined condensing temperature. Since post-defrosting is started, the condensing temperature can be lowered during normal refrigeration operation to allow steady operation, which greatly reduces lining costs.

On the other hand, since defrosting is started under high pressure and force, the defrosting time can be shortened, and as a result, there is an advantage that the inconvenience of excessively increasing the temperature inside the refrigerator is eliminated. This is a truly practical defrosting device that has various excellent effects.

[Brief explanation of the drawing]

FIGS. 1 to 3 show aspects of an example of the device of the present invention,
FIG. 1 is a piping system diagram of the refrigeration system, FIG. 2 is an exploded view of the electric control circuit, and FIG. 3 is a partially cutaway view of a cooling water solenoid valve. FIG. 4 is a piping system diagram of a conventional refrigeration system. 1... Solenoid valve for liquid refrigerant, 2... Solenoid valve for hot gas bypass, 3... Solenoid valve for cooling water, 4... Compressor, 5...Water-cooled condenser,
6... pressure reducer, 7... evaporator, 9...
... Hot gas bypass pipe, 13 ... Timer 19 ... Pressure detector, 21 ... Defrost detector.

Claims (1)

[Scope of utility model registration request] In a refrigeration system having a compressor 4, a water-cooled condenser 5, a pressure reducer 6, and an evaporator 7, a hot gas bypass pipe 9 is provided to bypass the water-cooled condenser 5 and the pressure reducer 6, and a refrigerant is supplied to the bypass pipe 9. A solenoid valve 2 that can shut off the flow is provided, and a pressure sensor 19 is provided in the water-cooled condenser 5 that issues a signal when the refrigerant pressure exceeds a predetermined pressure. While a solenoid valve 3 capable of suppressing water flow to the condenser 5 is provided, a periodic defrosting command is issued from the timer 13 and the signal from the pressure detector 19 is issued, so that The solenoid valve 2 is opened to perform defrosting operation, and the solenoid valve 2 is closed in response to either the defrosting release command from the timer 13 or the defrosting completion signal from the defrosting detector 21, and the defrosting operation is terminated. On the other hand, the solenoid valve 3 is operated to the water flow suppressing side by the defrosting command from the timer 13,
A defrosting device comprising a control circuit that maintains this operation while the solenoid valve 2 is open.