JPH0263137B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application) The present invention provides a defrosting system for air conditioners that can shorten the defrosting time by storing the heat source necessary for defrosting in the refrigeration cycle during defrosting operation. Regarding a control device.

(Prior art) When the air-to-air heat source side coil of an air conditioner acts as an evaporator in the heat pump heating cycle, frost forms on the coil surface, so this frost is melted to reduce the heat exchange capacity. It is well known that defrosting operation is performed to eliminate cold drafts, but defrosting operation is performed by switching from the heating cycle to cooling, and at the same time stopping the indoor fan to prevent cold drafts. This method has been widely used in the past.

In this case, it is difficult to obtain a sufficient heat source effective for defrosting due to the small heat exchange capacity of the user-side coil, so heat exchange with the refrigerant during the refrigeration cycle may be necessary, such as by attaching a refrigerant heater to the user-side coil. Conventionally, measures such as installing a heat storage tank capable of heating the refrigerant in conjunction with the refrigeration circuit have been taken. Therefore, it is publicly known.

However, in this type of system in which a refrigerant heater and a heat storage tank are installed together, there are problems in that the equipment cost is high and the machine body becomes large, which hinders the promotion of miniaturization.

Therefore, focusing on this problem, consideration has been given to effectively equipping the refrigeration cycle itself with a heat source for defrosting during defrosting, thereby simplifying the equipment while shortening the time required for defrosting. , Tokko Akira
One example is disclosed in Japanese Patent No. 52-17255.

(Problem to be Solved by the Invention) However, the system disclosed in the above publication utilizes the discharge pressure and discharge gas temperature that increase due to the continuation of the heating cycle after the blower is stopped by the defrosting signal to generate high pressure. The defrosting operation is performed by changing the cycle according to the instructions from the pressure switch, and when the cycle is reversed, the temperature of the refrigerant gas increases, making it possible to shorten the defrosting time, but after the blower is stopped,
Since the heating cycle is immediately started and the discharge pressure and discharge gas temperature are increased, the heat storage effect is inevitably limited due to the influence of the initial discharge pressure.

Thus, the present invention improves the heat storage effect compared to the past by performing a preliminary defrosting operation before continuing the heating cycle, and effectively retains a heat source for defrosting in the refrigeration cycle itself. The purpose is to encourage people.

(Means for Solving the Problems) However, as is clear from FIG. In an air conditioner in which the refrigeration cycle is switched from the heating cycle to the cooling cycle in response to a frost start command signal, and the fan 11 of the user side coil 6 is stopped to perform defrosting, the defrosting cycle is preliminarily set for a predetermined period of time. The defrosting operation is carried out by three elements: a heat storage operation means 1 which operates after a certain defrosting operation time according to a timer 25 to perform the defrosting operation and maintains the heating cycle, a pressure detection means 2, and a heat storage operation stop means 3. The heat storage operation means 1 constitutes a frost control device, and the heat storage operation means 1 is equipped with a timer, and the defrosting operation is performed for a predetermined period of time after the defrosting start command signal is transmitted, and the defrosting operation is performed after a certain period of time has elapsed. It has a structure that operates when the air conditioner is in the room and forcibly maintains the refrigeration cycle in the heating cycle.

On the other hand, the pressure detection means 2 has a structure that outputs an output at a set high range pressure within a range that does not overload the compressor whose discharge pressure of the refrigeration cycle is detected.

Further, the heat storage operation stop means 3 has a structure in which the output from the pressure detection means 2 causes the heat storage operation means 1 to be deactivated, thereby releasing the forced holding of the heating cycle and returning to the cooling cycle.

(Function) The present invention is applied to the user-side coil 6 where the fan 11 is stopped and the heat exchange capacity is reduced when defrosting is still required in the initial stage of the defrosting operation by the defrosting start command signal. Then, the heat storage operation means 1 supplies high-pressure refrigerant to store heat with the refrigerant, and after the heat storage is performed at the maximum allowable amount until the pressure detection means 2 is activated, switching to the defrosting operation using the cooling cycle, The heat exchange performance of the utilization side coil 6 during the defrosting operation can be enhanced to efficiently secure an effective defrosting heat source.

In this way, the defrosting time can be considerably shortened compared to the case where the cooling cycle is performed continuously, and the function equivalent to that provided with an auxiliary heat source can be exhibited.

(Example) Examples of the present invention will be described below based on the accompanying drawings.

FIG. 2 is a device circuit diagram of an air conditioner that is the basis of the present invention, and is a heating expansion device having a compressor 4, a four-way switching valve 7, a heat source side coil 5, and a check valve 10A connected in parallel. A cooling/defrosting expansion valve 9 having a valve 8 and a check valve 10B connected in parallel, and a user-side coil 6
A reversible refrigeration cycle is formed by the heating cycle in which the refrigerant flows in the direction shown by the solid line arrow, and the cooling cycle in which the refrigerant flows in the direction shown by the broken line arrow.

Furthermore, the cooling cycle allows defrosting operation during winter heating operation.

In Fig. 2, 11 is a fan for the coil 6 on the user side;
Reference numeral 12 indicates a fan for the heat source side coil 5, respectively.

In the air conditioner having the above configuration, a pressure switch 2 is attached to the high pressure side piping connected to the discharge side of the compressor 4, and the pressure switch 2 is installed in a high pressure range that does not overload the compressor 4. Pressure e.g. 24.5
It emits an output when the pressure reaches Kg/cm ³ , and this pressure switch 2 constitutes the pressure detection means 2 .

And the pressure switch 2 has a discharge pressure of 24.5Kg/
When it rises to ^cm3 , it emits an output that causes the normally open contact to close.

On the other hand, in FIG. 2, reference numeral 9 denotes a frost detector generally called a deicer, which is connected to a sensor 13 that detects when frost grows to a predetermined thickness on the heat transfer surface of the heat source side coil 5, such as the surface of the fins. At the same time, if heating operation is performed continuously from a state where no frost has adhered to the interior after defrosting, the time corresponding to the time (for example, 50 minutes) until a limited amount of frost grows on the surface of the fins is required. ) for a certain period of time (for example,
The device is equipped with a timer mechanism that emits a signal (10 minutes), and when both the signal from the timer mechanism and the signal notifying frost formation on the sensor 13 are transmitted, a defrosting start command signal is generated, for example, when a normally open contact is closed. Although not shown, this defrosting start command signal is issued in response to a defrosting completion detector command detected by an increase in the refrigerant output in the heat source side coil 5, etc., and a predetermined defrosting operation. It is canceled by a signal when the time elapses, for example, 10 minutes, or by a signal whichever is earlier.

As mentioned above, the defrosting control device related to the output contacts of the pressure switch 2 and the de-icer 9 includes the heat storage operation means 1 and the heat storage operation stop means 3, which are connected to the input section and the output section. Although it can be easily constructed by a microcomputer having a storage section and a central processing section, it can also be constructed by a simple contact circuit as described below.

FIG. 3 shows the basic circuit of the air conditioner, in which 4M is the compressor motor, 11M is the motor that drives the fan 11 of the user coil 6,
12M is a motor that drives the fan 12 of the heat source side coil 5; 7S is a solenoid for the four-way switching valve 7; 20
is an electromagnetic switch which closes by excitation of the solenoid 20S and energizes the compressor motor 4M; 21 is a room temperature controller; 22 is an air conditioning/heating selector switch; 23 is a solenoid 23A; normally open contacts 23B, 23C; Auxiliary relay with closing contacts 23D, 23E, 24
1 shows an auxiliary relay having a solenoid 24A, a normally open contact 24B, and a normally closed contact 24D, respectively.

The user side coil fan motor 11M is energized while the auxiliary relay 24 is de-energized.

When the room temperature is low during heating, the compressor motor 4M
When the room temperature is high during cooling, electricity is supplied by opening and closing the output contacts of the room temperature controller 21.

The heat source coil fan motor 12M is energized while the auxiliary relay 23 is deenergized.

The solenoid 7S of the four-way selector valve 7 is energized while the cooling/heating switch 22 is set to the cooling notch and is set to the heating notch, and the auxiliary relay 23 is energized, changing the refrigeration cycle to the cooling cycle. It operates to set.

The auxiliary relay 23 is energized when the heating/cooling changeover switch 22 is set to heating during the heating season, the auxiliary relay 24 is energized, and the pressure switch 2 is closed, and this energization is maintained by itself. At the same time, the auxiliary relay 24 is deenergized, thereby deenergizing it.

On the other hand, the auxiliary relay 24 continues to be energized while the cooling/heating changeover switch 22 is set to heating and the output contact of the de-icer 9 is made (issuing a defrosting command signal).

In the circuit explained above, the normally open contact 23B of the auxiliary relay 23 corresponds to the heat storage operation means 1, and on the other hand,
Solenoid 23A of auxiliary relay 23, self-holding contact 23C, and normally open contact 24B of auxiliary relay 24
The series circuit with this corresponds to the heat storage operation stop means 3.

The above configuration causes the heat storage operation means 1 to forcefully maintain the refrigeration cycle in the heating cycle at the same time as the defrosting start command signal is issued from the de-icer 9, but in the present invention, as shown in FIG. A timer 25 is added to the circuit, so that the heat storage operation means 1 is started after a certain period of time, for example, 2 to 3 minutes, has elapsed since the defrosting start command signal was sent.

In Fig. 4, the normally open contact 2 of the auxiliary relay 23
3B corresponds to heat storage operation means 1, while timer 2
The illustrated circuit, which is a combination of the drive unit 25S of No. 5, the time-limited normally open contact 25A, the time-limited normally closed contact 25B, the solenoid 24A of the auxiliary coil 24, and the normally open contact 24B, corresponds to the heat storage operation stop means 3.

That is, the timer 25 starts counting when the de-icer 9 closes its output contact, and keeps the normally closed contact 25B closed until a predetermined time period elapses, for example, 2 minutes, to energize the auxiliary relay 23 and perform defrosting operation. let them do it;
After 2 minutes, the contact 25B is opened and the contact 25A is opened.
The circuit is configured such that when the pressure switch 2 is closed, the heat storage operation is switched to, and when the pressure switch 2 is activated, the heat storage operation is stopped and the defrosting operation is started again.

The operation mode of this embodiment will be explained with reference to FIG. 5. When the de-icer 9 issues a defrosting command signal (a),
The auxiliary relay 23 is energized (b)' and the heat source side fan 12
Then, the user fan 11 stops, and the four-way switching valve 7 operates to switch the refrigeration cycle to the cooling cycle by energizing the solenoid 7S (wa).

In this way, the heating operation is switched to the defrosting operation. When the timer 25 operates and determines that the set time limit of 2 minutes has elapsed (F), the auxiliary relay 23 de-energizes (N), switches the four-way selector valve 7 to the heating cycle side, and at the same time switches the four-way switching valve 7 to the heating cycle side. The coil fan 12 is driven to start a so-called heat storage operation (Y).

When the force and temperature rise from this operating state and the pressure reaches 24.5Kg/ ^cm3 , the pressure switch 2 detects this (D) and closes the output contact (E), so the auxiliary relay 24 is activated. energize (b).

Therefore, the timer 25 is reset by the opening of the contact 24C, and the auxiliary relay 23 is energized by the return of the contact 25B to closed.As a result, the heat source side coil fan 12 is stopped and the four-way switching valve 7 is closed. The solenoid 7S is energized to switch to the cooling cycle (g) and the defrosting operation is performed again.

In this way, defrosting operation begins, but when the defrosting completion signal (J) or (R) is output from the de-icer 9, the output contact opens, and as a result, the auxiliary relay 24 is deenergized, and the auxiliary relay 23 is deenergized. Then, the solenoid 7S of the four-way switching valve 7 is de-energized, so the cooling cycle for defrosting is returned to the heating cycle, and both the fans 11 and 12 start blowing air, and the heating operation is started. It is started (wo).

The operating mode described above is shown in the graph of Figure 6, and as is clear from the graph, this example using heat storage operation was able to shorten the defrosting time by about 1 minute. .

(Effects of the Invention) The present invention is as detailed above, and when a defrosting start command is issued during heating operation, the heat of the user-side coil that has been warmed by heating operation is used as a heat source to set the timer. Since a medium defrosting operation is performed, it is possible to effectively utilize the heat of the user-side coil. Then, during the defrosting operation, the user-side coil fan is stopped, and after a predetermined period of time, a heating cycle is performed in a heat storage operation, which uses the heat of the refrigerant in the refrigeration cycle itself. By securing a portion of the heat of defrosting during frost operation, it is possible to significantly shorten the time required for defrosting, and preliminary defrosting operation can be continued for a certain period of time. The heat storage effect in heat storage operation becomes greater and contributes to shortening the defrosting time.

Furthermore, as shown in the embodiment, since all that is required is to switch the refrigeration cycle by switching the four-way switching valve, the handling is extremely simple, and the cost of the device is low, resulting in the effect of killing two birds with one stone.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram showing the basic configuration of the present invention, Fig. 2 is a circuit diagram of an air conditioner according to the basic part of the present invention, Fig. 3 is a developed electrical circuit diagram of the same device, and Fig. 4 is FIG. 5 is a developed diagram of an electric circuit according to an embodiment of the present invention, and FIG. 5 is a flow chart showing the operating mode of the control device, and FIG. 6 is a characteristic comparison diagram. 1... Heat storage operation means, 2... Pressure detection means, 3
... Heat storage operation stop means, 5 ... Heat source side coil, 6
...Using side coil, 9...Frost formation detector, 11...
Juan.

Claims (1)

[Claims] 1 Switch the refrigeration cycle from the heating cycle to the cooling cycle in response to the defrosting start command signal from the frost detector 9 that detects the frosting state of the heat source side coil 5, and stop the fan 11 of the user side coil 6. In an air conditioner that defrosts the air using
It has a timer 25 that causes the defrosting operation to be performed for a predetermined period of time in response to the transmission of the defrosting start command signal, and operates to forcibly maintain the refrigeration cycle in the heating cycle after the defrosting operation period has elapsed by the timer 25. a heat storage operating means 1 for detecting the discharge pressure of the refrigeration cycle; a pressure detecting means 2 for detecting the discharge pressure of the refrigeration cycle and generating an output according to a set high range pressure within a range that does not overload the compressor; A defrosting control device for an air conditioner, characterized in that it comprises a heat storage operation stop means 3 that deactivates the heat storage operation means 1 and releases the forced holding of the heating cycle by the generated output.