JPS6217572A - Defroster for air-cooled heat pump type refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a defrosting device which prevents liquid return and increases safety in an air-cooled heat pump refrigerator having a mechanism for defrosting by reverse cycle. Regarding the configuration of

(Prior art) In an air-cooled heat pump type refrigerator that operates a compressor with an unloader mechanism and switches to a defrosting cycle to melt frost attached to the heat source side coil, a differential pressure type four-way switching valve is particularly used. In some cases, switching is carried out 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 capable of defrosting operation that can eliminate such a 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 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 is quite difficult to set the time period for low capacity operation to an appropriate value. Another problem was that liquid return tends 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. .

The present invention was developed in an attempt to eliminate the deficiencies of the conventional equipment, and by gradually increasing the compression function from a low capacity at the start of defrosting, liquid return can be eliminated and accumulated. The purpose is to simultaneously maintain a high rate of heating capacity.

(Means for Solving the Problems) The present invention operates a compressor (1) having a multi-stage unloader mechanism (10) and switches the defrosting operation to a defrosting cycle according to the defrosting command 6. As a defrosting device for an air-cooled heat pump type refrigerator that is activated by a defrosting command and stopped by a defrosting completion command from a defrosting completion command unit α2, both the first capacity control means a3 and the second capacity control means 14) are used. It is composed of

The first capacity control means 031 operates according to the defrosting command from the defrosting command unit ω, and controls the unloader machine Ill no+ so that the compressor (1) has the minimum capacity, and also controls the unloader machine Ill no+ for about 30 seconds, for example. It is formed to be held for a predetermined short time.

10,000, the second capacity control means Q41 switches and operates following the first capacity control means Q31 to fully control the unloader mechanism +IO+ so that the compressor (1) has an intermediate capacity; is held for a predetermined short period of time, after which the unloader mechanism (IO) is made inactive.

(Function) The present invention uses the compressor fi+ to prevent liquid return at the start of defrosting.
By operating the compressor (1) at its minimum capacity and then performing a defrosting operation that increases the capacity to an intermediate capacity within a short period of time, the capacity is increased to the maximum capacity in the shortest possible time while preventing liquid from returning to the compressor (1). This enables efficient defrosting operation.

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

FIG. 1 shows an air-cooled heat pump type refrigerator, in which II+ is a compressor having an unloader tll+α, (21 is a four-way switching valve, 131 is a heat source side to air heat exchanger (hereinafter referred to as the heat source side coil), fu is a refrigerant regulator, (51 is an expansion valve for cooling, (61 is a user-side water heat exchanger (hereinafter referred to as a user-side coil), H-+ is an expansion valve for heating, (8A) to (
8D) are check valves for rectification, (91 is an accumulator, and by connecting the pipes as shown in the figure, a sealed circuit is formed to form a known reversible refrigeration cycle. In the cooling cycle, the refrigerant is As a result, the heat source side fill 131 functions as a condenser, the usage side coil (61) functions as an evaporator, and cold water for air conditioning is obtained in the usage side coil (61).

In addition, in the heating cycle, the refrigerant flows as indicated by the dashed arrow,
The heat source side coil 13+ functions as an evaporator, the usage side fill 161 functions as a condenser, and hot water for heating is obtained in the usage side coil 161.

The unloader mechanism 1101 in the compressor (1) has three unloader control valves (IIA) to (110), and when all of them are in the non-operating closed state, the compression is 4!1. (1) becomes 100% capacity, and when the first unloader control valve (IIA) is opened, the capacity becomes 70%.
When the second unloader control valve CIIB) is opened, the capacity becomes 40%, and the third
When the unloader control valve (110) is opened, the capacity is 12%.

At this time, when one unload valve is open, the other two
Two unload valves are controlled closed.

The 12% capacity in this case is a value that is even lower than the small capacity normally used during low loads, and, taking a screw compressor as an example, it performs almost no gas compression and only performs a pumping action. It is equivalent to such a minimal ability.

In addition, the unloader mechanism (101) 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 capacity reduction rate may be different from the above example, and various capacity control mechanisms are collectively called an unloader mechanism.

When the refrigerator is in heating operation, the heat source side fill +3
In that case, the refrigeration cycle is switched to the cooling cycle and defrosting is performed using the heat held by the refrigerant itself. A defrosting command device, for example, a coil temperature detector, is provided to detect the temperature and issue a defrosting command, while a first high-pressure valve is installed in the middle of the gas pipe connecting the four-way switching valve (21 and the heat source side coil 131). A defrost completion command lI2) is used which uses the force switch α2 to detect the completion of defrosting by the increase in pressure and issues a defrost completion command.

In addition, as a defrosting completion command device, there is also a temperature detector that detects the refrigerant temperature at the outlet of the heat source side filter Ill during the cooling cycle, and a defrosting command device that starts timing by the defrosting command and waits until the defrosting is completed. Various controllers such as a timer that issues a command when a predetermined time set in advance has elapsed can be used.

Therefore, in connection with the unloader mechanism 101, 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 u3, It is formed from a second capacity control means, a frost melting detection means (lω), and a third capacity control means [+61].

The above-mentioned defrosting output control system can be incorporated as a 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 α5), for example, a second high-pressure switch is interposed in a gas pipe connecting the four-way switching valve (2) and the heat source side coil 13) in a cooperative relationship with the high-pressure switch 112I. A power switch is used, and the first high pressure and pressure switch 021 as the defrosting completion command device closes the normally open contact as the high pressure and pressure increases (18 or more) due to complete defrosting. On the other hand, if the pressure is lower than that, for example 15 or more, the normally open contact is closed and the pressure is lowered to indicate that most of the frost has melted and a small amount of frost has formed. It is configured so that it can detect changes and issue command signals.

Next, the first capacity control means f131 operates in response to the defrosting command from the defrosting command device, and operates the third unloader control valve (110
) to control the unloader mechanism uO) to reduce the compressor (1) to the minimum capacity of 12% capacity, and to maintain this for a predetermined short period of time, for example, about 30 seconds.

Further, the second capacity control means [141] operates by switching over the first capacity control means a3, closes the third unload control valve (110), and closes the second unload control valve (IIE).
), and after a predetermined period of time, for example, about 30 seconds,
The second unloader control valve (CIIB) is closed, and the first unloader control valve (IIA) is kept closed to control the unloader mechanism 110) in a step-by-step manner to gradually increase the capacity to the maximum capacity. 100 capacity, the unloader mechanism is naturally configured to be inoperative.

Further, the third capacity control means aS is configured to control the frost melting detection means α5.
), the second high pressure and force switch α5) detects a high pressure and force of 15 degrees and issues a command signal, and in response to this, it generates a development force to the second unloader control valve (IIB), and the compressor ( 1
) to reduce the capacity to 40%.
0).

In the defrosting output control system having each of the functions described above, each capacity control means α3. α and αG are provided in the sequence controller αη shown in FIG. 2 High pressure force switch 1121. [151, various command devices such as operation relay, water circulation pump 1241 relay, stop relay, cooling/heating switching relay, cold/hot water temperature regulator, etc. are connected as devices for giving input commands, and 110,000, output terminal F! v, Q
For 91, the electromagnetic coil (to) of the electromagnetic switch for the pressure machine (1), the electromagnetic solenoid (2S) of the four-way switching valve 121
, the electromagnetic coil of the electromagnetic switch for the fan motor on the heat source side coil 131! 2B, the water circulation pump of the user side coil 16), the electromagnetic coil of the monthly electromagnetic M-closer, the electromagnetic solenoids (IIAS) to (llos) of the first to third unloader control valves (IIA) to (110), and the timer thermostat. A system defrosting command device and its relay (251) are connected as devices that provide drive output.

The sequence controller αη consists of a well-known microcomputer, and the input/output terminal section t1
81. α creation, power supply circuit, input circuit, timer circuit, output circuit, arithmetic control circuit, program counter, P-ROM,
Equipped with calculation result memory, cold and hot water set temperature, overcurrent, abnormally high pressure and force, heat source side fill temperature, pressure, outside air temperature,
Each basic control value such as and the control contents of the relay sequence are stored in the P-ROM, and compression mm is started and stopped during each cooling and heating operation, capacity control, and operation between heating and defrost. P-R for switching, pump down operation, etc.
It emits an output signal to perform the operation at any time based on the instructions of the program contents written in the OM.0 Using the electric control circuit explained above and the flowchart in Figure 3, switching control between defrosting operation and heating operation is performed. I will explain about it.

When a command to start heating operation is issued by operating a push button switch, etc., the sequence controller αη compares the water temperature of the user side fill (61) with the set temperature, and if it is determined that heating operation is necessary, starts each electromagnetic coil. ω, 21+,
It emits an output for excitation at +221.

The water circulation pump spider of the heat source side fill 131 and the use side fill 61 is energized to form a refrigeration cycle in which the refrigerant flows in the direction indicated by the broken line in FIG. 1. Heating operation starts.

In addition, the compressor! 11, the unloader control valves (IIA) to (110) are sequentially energized to appropriately perform an unloader operation in which the capacity is gradually increased from a low capacity operation.

During this heating operation, frost builds up on the heat source side coil 131, and the defrost command device - operates and issues a defrost command +(), so the electromagnetic solenoid (2S) is energized and the four-way switching valve +
2) to the cooling side, demagnetizes the electromagnetic coil Q9 and stops the fan of the heat source side filter 131, and at the same time, the sequence controller aω issues a command to operate the first capacity control means Q3. .

In this way, the refrigerator switches to defrosting operation and high-pressure refrigerant flows into the heat source side coil I31, thereby starting defrosting. In this case, the electromagnetic solenoid (1108) is excited by the operation of the first capacity control means a3. G/) to keep the unloader control valve (110) open.

Therefore, the compressor il+ is operated at a minimum capacity of 12%, and a switch is made to defrost without causing liquid return.

It is checked whether 30 seconds have elapsed in the defrosting operation at the minimum capacity, and when 30 seconds have elapsed, the first capacity control means 03) is deactivated, and the second capacity control means Q4I is activated. [4゜Second ability control means α
4 emits an output that fully energizes the electromagnetic solenoid (11BS) and de-energizes the electromagnetic solenoid (11os) at the same time as the operation, so the unloader mechanism floI is operated by the third unloader control valve (110) and the first unloader control valve (
IIA) is closed and the second unloader control valve (IIB) is opened (-4), and the compressor capacity increases stepwise to 40% capacity.

When 30 seconds have elapsed after checking (g) whether this 40% capacity operation has elapsed, for example, the second electromagnetic solenoid CIIBS is energized.
) to de-energize, the unloader mechanism +101 has all unloader control valves (IIA)
, CIIB), and (110) to close the valves.
increases gradually to 100% capacity.

As described above, the operation of the second capacity control means is completed 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, and its operation mode is is the fourth
As shown in the figure.

However, at the same time as the start of defrosting operation, the second high-pressure force switch α
6) is performing pressure detection, but as defrosting progresses and most of the frost melts, it detects that the high pressure has reached 15 degrees, and the switch αω is activated. vinegar)
Then, the third capacity control means αe is held in the open state (7), and the electromagnetic solenoid (11B8) is energized to keep the second unloader control valve CIIB in the open state ('7). Compression Ill 11 was operating at 100% capacity.
1 is 40% due to the operation of the unloader m tRIIO+
In order to continue defrosting operation due to the decrease in capacity, the increase in high pressure and pressure before the completion of defrosting becomes gradual as shown in Figure 5, and when defrosting is completed, the high pressure and pressure rises to 18 l. Therefore, the first high-pressure force switch α2 is activated.

Therefore, the sequence controller αη checks the operation of the first high-pressure force switch α2 and controls the electromagnetic solenoid (
2S) is deenergized and the four-way switching valve (2) is switched to the heating side, and at the same time, the electromagnetic filter f21) is energized to energize the fan of the heat source side coil L31.

Next, the first high-pressure force switch 1 as a defrosting completion command device
By returning I21 and the second high-pressure force switch α61 to the initial state, the third capacity control means [+61 is switched to the initial heating operation by thermo automatic control. At the start, 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 second capacity control means 14) are used in the same way as when starting the defrosting operation. It is a preferable embodiment to gradually increase the compressive force from a small capacity, and this state is 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 fl+ 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 increase in pressure in the side coil C31 is controlled slowly, residual frost can be removed and defrost can be carried out reliably without causing false detection of completion of defrosting.

In addition, in the above embodiment, the capacity of the compressor H1 was controlled from 12% → 4o% → 100% from the start of defrosting, but this is %1
The control may be performed as follows: 2% → 40% → 70% → 100 (see the broken line in Figure 4).
It is sufficient to do this for 0 seconds at a time.

(Effects of the Invention) As detailed above, the present invention operates the unloader mechanism +10) at the start of defrosting operation to control the capacity of the compressor so that it gradually increases from the minimum capacity to the maximum capacity in a short period of time. As a result, the suction force of the compressor il+ is reduced, the amount of liquid returned can be extremely reduced, and liquid compression in the compressor can be reliably prevented.

Moreover, the capacity of the first compressor (1) is increased by unloader mechanism + IO
Since the capacity is set to the minimum possible in I, 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.

[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. Flow Chart 1 FIGS. 4 and 5 are also defrosting operation characteristic diagrams. (1) Compressor + 1101 Unloader mechanism. +121...Defrost completion command device. a3...first ability control means. ■...Second ability control means. Garden... Defrost command device.

Claims (1)

[Claims] 1. A compressor with a multi-stage unloader mechanism (10) (
1) and switches to the defrost cycle.The air-cooled heat pump type operates the defrost operation in response to the defrost command from the defrost command device (26), and stops it in response to the defrost completion command from the defrost completion command device (12). In the refrigerator, first capacity control means (13) operates in accordance with the defrosting command to control the unloader mechanism (10) so that the compressor (1) reaches a minimum capacity and maintains this for a predetermined period of time; , the unloader mechanism (10) is switched and activated following the first capacity control means (13) to control the unloader mechanism (10) so that the compressor (1) has an intermediate capacity and maintains this for a predetermined period of time; second capacity control means (
14) A defrosting device for an air-cooled heat pump type refrigerator, comprising: