JPH0435662B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides defrosting by reverse cycle.
The present invention relates to the configuration of a defrosting device that prevents liquid return and is highly safe in an air-cooled heat pump refrigerator having a mechanism for performing this.

(Prior Art) In an air-cooled heat pump type refrigerator that operates a compressor having an unloader mechanism and switches to a defrosting cycle to melt frost attached to a heat source side coil,
In particular, when a differential pressure type four-way switching valve is used, switching is performed quickly, so pressure fluctuations between the high pressure side and the low pressure side are severe, and there is a risk that liquid may return to the compressor.

As a device that can perform defrosting operation that can eliminate such liquid return phenomenon, there is a device known from Japanese Patent Publication No. 59-6345, etc. The compressor is configured to operate the compressor at low capacity by operating the unloader mechanism for a certain period of time, and then switch to high capacity operation.

(Problems to be Solved by the Invention) With the above-mentioned conventional device, if the duration of low-capacity operation is prolonged, the integrated heating capacity of the heat pump type refrigerator will be drastically reduced, which is undesirable; If the load factor is increased, liquid return may not be completely avoided, so it has been quite difficult to set the time period for low capacity operation to an appropriate value. Another problem is that liquid returns tend to occur immediately after switching to a sudden increase in the load factor, which forces low-capacity operation to take a considerable length of time, making it difficult to maintain a high cumulative heating capacity. Ta.

The present invention was developed in an attempt to eliminate the deficiencies of the conventional devices, and by gradually increasing the compression function from a low capacity at the start of defrosting, liquid return can be eliminated. The purpose of the present invention is to achieve both of this and the maintenance of a high rate of cumulative heating capacity.

(Means for Solving the Problems) Accordingly, the present invention provides a multi-stage unloader mechanism 1
0, and switches to the defrosting cycle to perform a defrosting operation to melt the frost attached to the heat source side coil 3 according to the defrost command from the defrost command unit 26, and also to switch to the defrost cycle In the air-cooled heat pump refrigerator, the defrosting completion command unit 12 is activated when the pressure in the gas pipe connected to the gas pipe reaches a predetermined set pressure, and the defrosting operation is stopped based on this command. The unloader mechanism 10 is capable of controlling the compressor 1 to at least 100% capacity, intermediate capacity, and minimum capacity lower than the intermediate capacity, while at the same time, during the defrosting operation, the pressure in the gas pipe connected to the heat source coil 3 is A defrosting detection means 15 is provided which issues a defrosting detection signal when the pressure reaches a predetermined set pressure, which is slightly lower than the pressure at the time of activation of the defrosting completion command device 12, and the compressor is activated by the defrosting command. 1
a first capacity control means 13 that controls the unloader mechanism 10 so that the unloader mechanism 10 has the minimum capacity and maintains this state for a predetermined period of time; A second capacity control means 14 controls the unloader mechanism 10 so as to maintain this state for a predetermined period of time, and then deactivates the unloader mechanism 10, and receives a detection signal from the frost melting detection means 15. The second capacity control means 14 then switches and operates, and controls the unloader mechanism 10 so that the compressor 1 has an intermediate capacity. Third ability control means 16 held until issued
It is characterized by having the following.

(Function) The present invention operates the compressor 1 at a low capacity to prevent liquid return at the start of defrosting, and then performs a defrosting operation that increases the capacity to an intermediate capacity in a short period of time. It is possible to achieve efficient defrosting operation by reaching the maximum capacity in as short a time as possible while preventing liquid from returning to the machine 1.

(Example) Hereinafter, one example of the present invention will be described based on the accompanying drawings.

Figure 1 shows an air-cooled heat pump type refrigerator.
1 is a compressor having an unloader mechanism 10, 2 is a four-way switching valve, 3 is a heat source side to air heat exchanger (hereinafter referred to as a heat source side coil), 4 is a refrigerant regulator, 5 is an expansion valve for cooling, and 6 is a cooling expansion valve. A user-side water heat exchanger (hereinafter referred to as a user-side coil), 7 is a heating expansion valve, 8A to 8D are check valves for rectification, 9 is an accumulator,
By connecting the pipes as shown in the diagram, a sealed circuit is formed, forming a known reversible refrigeration cycle. In the cooling cycle, the refrigerant flows as shown by the solid arrow, and the heat source side coil 3 is connected to the condenser, and the user side The coil 6 functions as an evaporator, and cold water for cooling is obtained in the user side coil 6.

Further, in the heating cycle, the refrigerant flows as indicated by the broken line arrow, the heat source side coil 3 acts as an evaporator, the user side coil 6 acts as a condenser, and hot water for heating is obtained in the user side coil 6.

The unloader mechanism 10 in the compressor 1 has three unloader control valves 11A to 11C, and when they are all inactive and closed, the compressor 1 has 100% capacity and the first When the unloader control valve 11A is opened, the capacity is 70%, and when the second unloader control valve 11B is opened, the capacity is 40%.
When the third unloader control valve 11C is opened, the capacity becomes 12%.

Note that at this time, when one unload valve is open, the other two unload valves are controlled to be closed.

The 12% capacity in this case is a value that is lower than the small capacity normally used during low loads.
Taking a screw type compressor as an example, it has an extremely small capacity that hardly compresses gas and only performs a pumping action.

In addition, the unloader mechanism 10 may be one that can control the compression capacity by steplessly or stepwise controlling the rotational speed of the motor that drives the compressor 1. The rate may be different from that in the above example, and various capacity control mechanisms are collectively referred to as an unloader mechanism.

When the refrigerator is in heating operation, frost forms on the heat transfer portion of the heat source coil 3, so in that case, the refrigeration cycle is switched to the cooling cycle and defrosted using the heat held by its own refrigerant. Although not shown, the heat source side coil 3 is provided with a defrost command device, such as a coil temperature sensor, which detects frost formation and issues a defrost command, while the four-way switching valve 2 and the heat source side coil A first high-pressure force switch 12 is interposed in the middle of the gas pipe connecting 3, and the switch 12 detects the completion of defrosting by the increase in pressure and issues a defrosting completion command. A defrosting completion command device 12 is used.

Therefore, in connection with the unloader mechanism 10, the refrigerator is provided with a defrosting output control system that controls the compression function during defrosting operation, and the control system includes a first capacity control means 13, Second capacity control means 1
4. Frost melting detection means 15 and third ability control means 16
It is formed from

The above-mentioned defrosting output control system can be incorporated as part of the function in a microcomputer that centrally controls the overall operation of the refrigerator, or it can be formed as a circuit using a contact system. Regarding 15, for example, a second high pressure force switch is interposed in a gas pipe connecting the four-way switching valve 2 and the heat source side coil 3 in a cooperative relationship with the high pressure force switch 12. The first high pressure and force switch 12, which serves as the defrosting completion command, closes the normally open contact as the high pressure and force increases (18Kg/cm ² or more) due to complete defrosting. On the other hand, if the pressure is lower than that, for example 15 kg/cm ² or higher, the normally open contact will close, indicating that most of the frost has melted and a small amount of frost has formed. It is configured so that it can detect changes in pressure and issue a command signal.

Next, the first capacity control means 13 operates in response to the defrosting command from the defrosting command device, and outputs a valve opening output to the third unloader control valve 11C to control the unloader mechanism 10.
The compressor 1 is controlled to reduce the capacity of the compressor 1 to a minimum capacity of 12% capacity, and is configured to maintain this for a predetermined period of time, for example, about 30 seconds.

Further, the second capacity control means 14 switches and operates following the first capacity control means 13, closes the third unload control valve 11C, opens the second unload control valve 11B, and operates for a predetermined period of time. After a period of time, for example, about 30 seconds, the second unloader control valve 11B is closed, and the first unloader control valve 11A is kept closed to gradually increase the unloader mechanism 10 to its maximum capacity. Control the final stage
100 capacity, the unloader mechanism is naturally configured to be inactive.

Further, the third capacity control means 16 is configured such that the second high pressure force switch 15 as the frost melting detection means 15 is 15
When a high pressure force of Kg/cm ² is detected and a command signal is issued, the unloading mechanism 10 receives this and issues a development force to the second unloader control valve 11B to reduce the compressor 1 to 40% capacity. It is configured to control the

In the defrosting output control system having each of the functions described above, each capacity control means 13, 14, 16 is provided in a sequence controller 17 shown in FIG. , the contact 25a of the relay 25 of the defrosting command device 26 to be described later, the first and second high-pressure force switches 1
2, 15, various command devices such as an operation relay, a relay for the water circulation pump 24, a stop relay, a cooling/heating switching relay, and a cold/hot water temperature controller are respectively connected as devices for giving input commands; For the electromagnetic coil 2 of the electromagnetic switch for the compressor 1,
0, the electromagnetic solenoid 2S of the four-way switching valve 2, the fan 23 of the heat source side coil 3, the electromagnetic coil 21 of the electromagnetic switch for the motor, the electromagnetic coil 22 of the electromagnetic switch for the use side coil 6, the water circulation pump 24, the first to the first 3
The electromagnetic solenoids 11AS to 11CS of the unloader control valves 11A to 11C, a timer thermo-type defrosting command device 26, and its relay 25 are connected as devices for providing drive output, respectively.

The sequence controller 17 consists of a well-known microcomputer, and the
It is equipped with output terminal sections 18 and 19, a power supply circuit, an input circuit, a timer circuit, an output circuit, an arithmetic control circuit, a program counter, a P-ROM, and an arithmetic result memory. ,
Each basic control value such as heat source side coil temperature, pressure, outside air temperature, etc. and relay sequence control details are displayed on P-
Programs stored in the ROM and written in the P-ROM to control the start/stop of the compressor 1, capacity control, operation switching between heating and defrost, pump down operation, etc. during cooling and heating operations. It emits an output signal so that it can be performed at any time based on the content instructions.

The switching control between the heating operation and the defrosting operation will be explained using the electric control circuit described above and the flowchart shown in FIG.

When a command to start heating operation is issued by operating a push button switch, sequence controller 1
7 compares the water temperature of the user side coil 6 with a set temperature, and if it is determined that heating operation is necessary, outputs an output for excitation to each of the electromagnetic coils 20, 21, 22.

Thus, the compressor 1, the fan 2 of the heat source side coil 3
3. The water circulation pumps 24 of the user-side coils 6 are energized to form a refrigeration cycle in which the refrigerant flows in the direction indicated by the dashed arrow in FIG. 1, and heating operation is started.

In addition, when the compressor 1 is started, the unloader control valves 11A to 11C are sequentially energized to perform an unloader operation in which the capacity is sequentially increased from a low capacity operation as appropriate.

During this heating operation, the defrost command device 26 operates as frost builds up on the heat source side coil 3 and issues a defrost command (a), so the electromagnetic solenoid 2S is energized and the four-way switching valve 2 is cooled. At the same time, the electromagnetic coil 19 is demagnetized and the fan 23 of the heat source side coil 3 is switched to the side.
At the same time, the first capacity control means 13
sequence controller 15 to operate
issues a command (b).

In this way, the refrigerator switches to defrosting operation and the high-pressure refrigerant flows into the heat source side coil 3 to start defrosting. In this case, the first capacity control means 13
As a result, the electromagnetic solenoid 11CS is energized and the unloader control valve 11C is kept open (c).

Therefore, the compressor 1 is operated at a minimum capacity of 12%, and a switch is made to defrost that does not cause liquid return.

Check (d) whether or not 30 seconds have elapsed in the defrosting operation at this minimum capacity, and if 30 seconds have elapsed, the first
While turning the capacity control means 13 into non-operation,
The second capacity control means 14 is activated (e).

Since the second capacity control means 14 emits an output that excites the electromagnetic solenoid 11BS and de-energizes the electromagnetic solenoid 11CS at the same time as the operation,
The unloader mechanism 10 has a third unloader control valve 11
C and the first unloader control valve 11A are closed, and the second unloader control valve 11B is opened, respectively (f), and the capacity of the compressor 1 is gradually increased to 40%.

A check is made to see if this 40% capacity operation has elapsed, for example, for 30 seconds, and when 30 seconds have elapsed, the second capacity control means 14 outputs an output that changes the energized second electromagnetic solenoid 11BS to de-energized state. As a result, the unloader mechanism 10 closes all the unloader control valves 11A, 11B, and 11C (H), and as a result, the compressor 1 gradually reaches 100% capacity. To increase.

As described above, the second capacity control means 14 completes its operation when one minute has passed from the start of defrosting, and from then on, the compressor 1 performs compression operation for defrosting at full capacity.
Its operating mode is as shown in FIG.

However, at the same time as the defrosting operation starts, the second high pressure force switch 15 detects the pressure, but as the defrosting progresses and most of the frost melts, the high pressure force increases to 15 kg/m. ² and checks that the opening/closing section 15 is activated, the third capacity control means 16 is held in the activated state, and the electromagnetic solenoid 11BS is energized to control the second unloader. The valve 11B is kept open.

In this way, the compressor 1, which was operating at 100% capacity, is reduced to 40% capacity by the operation of the unloader mechanism 10, and in order to continue defrosting operation, the increase in high pressure and pressure before the completion of defrosting is as shown in Fig. 5. As shown in
When defrosting is complete, the high pressure is 18Kg/cm ²
The first high-pressure force switch 12 is activated.

Therefore, the sequence controller 17 checks the operation of the first high-pressure force switch 12, de-energizes the electromagnetic solenoid 2S, switches the four-way selector valve 2 to the heating side, and energizes the electromagnetic coil 21. to energize the fan 23 of the heat source side coil 3 (Y).

Subsequently, the first high pressure and pressure switch 12 and the second high pressure and pressure switch 15 as the defrosting completion command device return to their initial states, thereby controlling the third capacity control means 16.
is switched to the initial heating operation by automatic thermo control.

Note that when the heating operation is started by switching at the end of defrosting, the refrigeration cycle is switched, so in order to prevent the liquid from returning to the compressor 1, the first capacity control means 13 and the It is a preferable embodiment to use the two-capacity control means 14 to gradually increase the compression function power from a small capacity, and this state is as shown in FIG.

In the embodiment described above, since the compressor 1 is controlled to gradually increase the capacity from the minimum capacity to the full capacity at the start of the defrosting operation, liquid return can be reliably prevented.

In addition, during defrosting operation, the compressor 1 is operated at 100% high capacity until most of the frost melts to maintain high defrosting capacity, and then operated at low capacity until the defrosting is completed. Since the rise in pressure in the side coil 3 is controlled slowly, residual frost can be removed without causing false detection of completion of defrosting, and reliable defrosting can be performed.

In the above example, the capacity of the compressor 1 was controlled from 12% → 40% → 100% from the start of defrosting, but this is 12% → 40% → 70% → 100% (see the broken line in Figure 4).
In this case, each capacity control operation may be performed for 30 seconds each.

(Effects of the Invention) As described in detail above, the present invention operates the unloader mechanism 10 at the start of defrosting operation to control the capacity of the compressor 1 so that the capacity is gradually increased from the minimum capacity to the maximum capacity in a short period of time. Since the suction force of the compressor 1 is reduced, the amount of liquid returned can be extremely reduced.
Liquid compression in the compressor can be reliably prevented.

Moreover, the capacity of the first compressor is increased to 1 unloader mechanism.
Since the capacity is set to the minimum possible at 0, it is possible to quickly shift to 100% capacity in a short period of time while suppressing liquid return, making it possible to keep the time required for defrosting short and increase the cumulative heating capacity. It is especially effective when used in refrigerators with rotary compressors such as scrolls and screws.

Also, before the defrosting is completed, the unloader mechanism 10
Since the compressor 1 is set from 100% capacity to intermediate capacity by activating the Reliable defrosting can be achieved by removing residual frost without causing frost to grow.

[Brief explanation of drawings]

Fig. 1 is a device circuit diagram of a heat pump refrigerator according to an embodiment of the present invention, Fig. 2 is a schematic diagram of a sequence controller, and Fig. 3 explains a defrosting operation mode according to an embodiment of the present invention. The flow diagrams, FIGS. 4 and 5, are also defrosting operation characteristic diagrams. 1... Compressor, 10... Unloader mechanism, 12
...Defrosting completion command device, 13...First capacity control means, 14...Second capacity control means, 26...Defrosting command device.

Claims (1)

[Claims] 1 Operate the compressor 1 having the multi-stage unloader mechanism 10, switch to the defrost cycle, and perform the defrost operation to melt the frost attached to the heat source side coil 3 according to the defrost command from the defrost command unit 26. At the same time, when the pressure in the gas pipe connected to the heat source side coil 3 reaches a predetermined set pressure, the defrosting completion command 12 is activated and the defrosting operation is stopped based on this command. In the machine, the multi-stage unloader mechanism 10 has at least 100% capacity;
While the compressor 1 can be controlled to an intermediate capacity and a minimum capacity lower than the intermediate capacity, during the defrosting operation, the pressure in the gas pipe connected to the heat source side coil 3 causes the defrosting completion command unit 12 to operate. A defrost detection means 15 is provided which issues a defrost detection signal when the pressure reaches a predetermined set pressure, which is slightly lower than the normal pressure. a first capacity control means 13 that controls the mechanism 10 and maintains this state for a predetermined period of time; and a first capacity control means 13 that switches and operates following the first capacity control means 13 so that the compressor 1 has an intermediate capacity. a second capacity control means 14 which controls the unloader mechanism 10 and maintains this state for a predetermined period of time and then deactivates the unloader mechanism 10; and a second capacity control means which receives a detection signal from the frost melting detection means 15 and 14, the unloader mechanism 10 is controlled so that the compressor 1 has an intermediate capacity, and this state is maintained until the defrosting completion command is issued by the defrosting completion command unit 12. 1. A defrosting device for an air-cooled heat pump type refrigerator, characterized in that it comprises means 16.