JPS62223552A - Air conditioner defrosting control device - 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 Field of Industrial Application The present invention relates to a defrosting control device for a separate heat pump air conditioner, and particularly to a defrosting control device for detecting frost on an outdoor heat exchanger indoors. It's the same thing.

Prior Art In conventional air conditioners, as shown in Japanese Patent Publication No. 59-34255, frost formation on the outdoor heat exchanger is based on both temperature changes in the indoor heat exchanger and changes in the indoor temperature. Technology has been developed to detect conditions and control heating and defrosting operations.

Problems to be Solved by the Invention However, in such a conventional configuration, the difference (Tc - Ta) between the corrected temperature Tc of the indoor heat exchanger and the indoor temperature Ta is
A defrosting signal is obtained when the temperature drops by a certain value from the maximum value (Tc - Ta)max, but the correction temperature Tc of the indoor heat exchanger is a correction value up to the minimum set air volume. When an air conditioner is used indoors, the filter installed in front of the indoor heat exchanger becomes clogged with dust, which often causes the air volume to drop below the air conditioner's minimum setting.

Difference between the corrected temperature Tc and the indoor temperature Ta (Tc - Ta)
However, there are cases where the value does not decrease by a certain value from the maximum value (T c - T a)wwax, and there is a practical problem of not performing defrosting operation even though the outdoor heat exchanger is frosted. There's a problem.

In addition, the compression function power differs between 50Hz and 60Hz depending on the power supply frequency, and in general, the pressure is higher at 60) 1z, and even at the same indoor heat exchanger temperature, at 50Hz and 60Hz, the outdoor heat exchanger's The frosting conditions are different,
Accurate defrosting judgment could not be made.

As described above, the conventional technology has problems, and improvements are required.

The present invention solves the above-mentioned conventional problems, and provides a defrosting control device whose operation can be ensured without sacrificing the advantages of the prior art.

Means for Solving the Problems In order to solve the above problems, the present invention, as shown in FIG. 1, switches the refrigeration cycle from the heating cycle to the defrosting cycle. a first time measuring means for measuring the time since then, a set time T1 storage means for storing a preset time, and a time detected by the first time measuring means and the set time T1 storage means. a first comparing means that detects and outputs the coincidence of the set times; a second time measuring means that measures the time from the start of restarting the compressor after the compressor is temporarily stopped;
Set time T2 that stores the preset time
a storage means, a second comparison means for detecting and outputting a match between the time detected by the second time meter 41g means and the time set in the set time T2 storage means, and a refrigerant inlet of the indoor heat exchanger. a first temperature detection means for detecting the temperature of the pipe connected to the side (during heating operation); and a second temperature detection means for detecting the temperature of the pipe connected to the central part of the indoor heat exchanger. , set temperature storage means for storing a certain set temperature value for switching the heating cycle to the defrosting cycle, and 50/60)1z clock input means for inputting the power supply frequency;
50) 50/60) 1z discrimination means for discriminating 1z/60) 1z, set temperature switching means for switching the set temperature value of the set temperature storage means based on an output signal from the discrimination means, and the first temperature detection. The temperature detected by the means and the second
a third comparing means for detecting and outputting a difference between the temperature detected by the temperature detecting means and the temperature being lower than a certain set temperature value stored in the set temperature storing means; and a current detecting means for detecting a power supply current. , a set current storage means that stores a set current value for switching the heating cycle to the defrosting cycle, and an output that detects that the current detected by the current detection means has decreased by the set current value stored in the set current storage means. The heating cycle is determined by a fourth comparing means, a set time elapsed signal from the first comparing means or a set time elapsed signal from the first and second comparing means, and a differential temperature value decrease signal from the third comparing means. and a selection means for controlling switching of the refrigeration cycle from heating operation to defrosting operation in accordance with the output of the determination means.

Effect: With this configuration, heating operation is ensured until a predetermined time has elapsed from the start of heating operation, and after the predetermined time has elapsed, the compression is further increased due to the detected temperature difference between the two temperature detecting means and the detected current of the current detecting means. When restarting the machine, the defrosting operation is controlled after a predetermined period of time has elapsed from the start of restart.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 2 to 6. FIG. 2 is a refrigeration cycle diagram showing one embodiment of the present invention. In Figure 2, the refrigeration cycle consists of compressor 1
, a four-way switching valve 2, an indoor heat exchanger 3, a pressure reducer 4, and an outdoor heat exchanger 5 are connected in sequence.

Reference numeral 6 denotes a pipe temperature detection element, which is attached to a pipe that is on the refrigerant inlet side of the indoor heat exchanger 3 (condenser) during heating. Similarly, 6'' is a pipe temperature detection element, which is attached to the pipe in the center of the indoor heat exchanger 3 and detects the refrigerant temperature in the center of the heat exchanger. The refrigerant flows in the direction of the solid line arrow, and during heating operation, the four-way switching valve 2 switches so that the refrigerant flows in the direction of the broken line arrow in Fig. 2.Furthermore, the compressor 1° four-way switching valve 2. Pressure reducer 4. Outdoor heat exchanger 5 and outdoor blower 8 are installed in outdoor unit A, and the above-mentioned indoor heat exchanger 3. Piping temperature detection elements 6 and 6' and indoor blower 7, and power supply current are connected to Current detection element 1 to detect
7. An operation control section (not shown) having a microcomputer (hereinafter abbreviated as microcomputer) programmed with a timer function, temperature control function, etc. is provided in the indoor unit B. Here, the pipe temperature detection element 6 is connected to the indoor blower 7.
It should be installed in a location away from the ventilation circuit where it will not be affected by the air flow. Alternatively, the location may be near indoor unit B.

FIG. 3 is a main circuit diagram of the operation control section.

In FIG. 3, the microcomputer 9 includes a storage section 10 for storing a timer count value for determining the operating time;
A drive signal generating means 11 that generates an appropriate output signal by comparing a timer count value stored at 0 with an input value, a storage unit 10 that stores a timer count value that determines the restart time, and The drive signal generation means generates an appropriate output signal by comparing the timer count value and the input value. The input side of the microcomputer 9 is connected via a comparator 12 to a pipe temperature detection element 6 (for example, a pipe thermistor or thermoelectric couple element), which is a temperature detection means, and a resistor 13 whose resistance value can be changed as necessary. a heat exchanger temperature detecting element 6' (for example, a piping thermistor or a thermal lightning pair element), and a second temperature detecting means comprising a resistor 13' whose resistance value can be changed as necessary. an arithmetic processing unit 14 that processes signals from 15. and a resistance value that can be changed as needed;
16 are connected.

Further, on the input side of the microcomputer 9, the voltage supplied from the AC power source is stepped down by an I-lance 22, converted to rectified waveform by a diode bridge 23, and this waveform is connected to an inverter 24.
A 50/60 Hz clock signal generation circuit 25 is connected to the microcomputer 9, which converts the clock signal into a 50/60 Hz clock signal.
Receiving the signal from the 0/60Hz clock signal generation circuit 25,
5011 by 50/60Hz control means (not shown)
z or 60 Hz. Here, if the frequency is 60Hz, the microcomputer 9 outputs Hi from the P1 port, and the resistor 26
The reference voltage divided by resistors 15 and 16 is raised through the resistor 15 and 16, and the set temperature is raised. Furthermore, on the input side of the microcomputer 9, a current detection element 17 (for example, a current transformer) serving as a current detection means is connected to a current-voltage conversion circuit 18 and a current setting resistor 19.20 whose resistance value can be changed as necessary. and are connected via a comparator 21.

In addition, on the output side, switching transistors TR1 to T
A relay R1 that drives a four-way switching valve coil, which is a driving means, a relay R2 that drives the indoor blower 7, a relay R3 that drives the outdoor blower 8, and a relay R4 that drives the compressor 1 are connected via R4.

Here, when comparing the configuration of FIG. 3 with the first configuration, the pipe temperature detection element 6 and the resistor 13 correspond to the first temperature detection means in FIG. 13' corresponds to the second temperature detection means, and comparator 1
2 corresponds to the third comparator in FIG. corresponds to the 50/60Hz clock input means in FIG. 1, and the P ebort and resistor 26 of the microcomputer 9 correspond to the set temperature switching means.

The current detection element 17 and the current-voltage conversion circuit 18 are the first
The resistors 19 and 20 correspond to the set current storage means in FIG. 1, the comparator 21 corresponds to the fourth comparator in FIG.
corresponds to the 50/60 Hz discrimination means, set time storage means, time measurement means, determination means, and selection output means in FIG. 1, and among them, the drive signal generation means 11 corresponds to the determination means and selection output means.

Next, the operation from the start of heating operation to defrosting operation will be explained. The discharge refrigerant temperature of the compressor 1 is Td, the suction refrigerant temperature of the compressor 1 is Ts, and the discharge pressure of the compressor 1 is Pd.
, the suction pressure of the compressor 1 is Ps, and the polytropic index is n (where 1 < n < k, where is an adiabatic compression index), then the discharge refrigerant temperature Td is expressed by the following formula: Td=Ts・(g) Flat Ps Therefore, when the outdoor heat exchanger 5 is not frosted, the suction refrigerant temperature Ts is high and the discharge refrigerant temperature Td is also high, but as the outside air decreases and the frost grows, the suction refrigerant temperature Ts decreases. The discharge refrigerant temperature Td also decreases.

At the same time, the suction pressure Ps and the discharge pressure Pd also decrease.

The pipe temperature detection element 6 is installed in the inlet pipe of the indoor heat exchanger 3, and detects the temperature of the part through which the high-temperature, high-pressure superheated refrigerant gas discharged from the compressor 1 flows. Compared to this, the temperature is lowered by a predetermined temperature due to heat loss in internal and external connecting pipes, etc. Further, the heat exchanger temperature detection element 6'' is provided almost at the center of the indoor heat exchanger 3, and is a part through which the high temperature and high pressure refrigerant gas discharged from the compressor 1 flows, and is a part through which the refrigerant gas discharged in the gas phase flows. This is the part where the gas-liquid two-phase state changes to the liquid phase, but its temperature is considered to be almost constant and is generally referred to as the condensation temperature. Regarding the relationship between the temperature and the condensation temperature, when the refrigerant gas discharged from the compressor 1 flows into the heat exchanger 3 in a gas state with less superheated region, the temperature difference becomes smaller.Therefore, as shown in FIG. When the outdoor heat exchanger 5 is not frosted, the suction refrigerant temperature Ts of the compressor 1 is
Indoor heat exchanger 3 where the temperature of the inlet pipe of indoor heat exchanger 3 is low
The pipe temperature t2 at the center of the indoor heat exchanger 3 is both high, and gradually decreases as frosting progresses, and when a frosting state that significantly reduces the heating capacity is reached, the inlet pipe temperature t of the indoor heat exchanger 3 increases.
□ decreases extremely, and at the same time, the temperature t2 of the central pipe of the heat exchanger 3 also decreases, and the difference disappears, and □ progresses to almost the same state.

Further, the power supply current of the air conditioner has a value that roughly follows the discharge refrigerant temperature Td in proportion, and as shown in FIG. 4, it has a value that roughly follows the detection of the pipe temperature detection element 6. However, when the amount of refrigerant in the refrigerant cycle of the air conditioner decreases, the current value tends to be relatively low. That is,
If the temperature difference between the inlet piping temperature t and the central piping temperature t2 becomes less than the set piping temperature, the heating capacity will decrease and frost formation has progressed, so it is necessary to defrost.

Further, depending on the power supply frequency, the capacity of the compressor 1 differs between 50 Hz and 60 Hz, and the high pressure and discharge temperature at the time of frost formation of the outdoor heat exchanger 5 differ. That is, 5
Generally, the inlet pipe temperature t of the indoor heat exchanger 3 is different between 0Hz and 60Hz, and the set dust resistance t is 50il z and 6
At 0Hz, defrost determination is performed by switching.

In this way, the inlet pipe temperature of the indoor heat exchanger 3 is the temperature of the refrigerant gas in the superheated region, so it is not easily affected by the air volume of the blower 7, and the temperature of the central pipe of the indoor heat exchanger 3 is Since t2 detects the condensation temperature, it is stable, and by measuring the temperature difference 11-12, it is possible to accurately determine the defrosting operation.

Next, we will use Figure 6 to explain the behavior when the amount of refrigerant in the refrigeration cycle is insufficient, when it gradually leaks due to long-term use, and when the compressor is restarted after stopping. As is well known, when the amount of refrigerant is insufficient, the amount of refrigerant circulated within the refrigeration cycle decreases, the temperature of the refrigerant discharged from the compressor increases, and the temperature of the suction refrigerant also increases. Furthermore, the temperature difference between the two also increases.

On the other hand, of course the pressure will drop in the refrigeration cycle,
The temperature of the refrigerant in the evaporator also decreases as the pressure decreases, and due to heat exchange with the outside air, frost formation progresses during heating operation than during constant refrigerant amount operation. In addition, the high pressure of the power supply current decreases due to a decrease in the amount of refrigerant circulation.
In addition, the difference between high pressure and low pressure becomes smaller, and the amount of work of the compressor decreases, compared to steady operation. Therefore, the difference Δt between the suction refrigerant temperature Ts of the compressor 1, the inlet temperature of the indoor heat exchanger, and the indoor heat exchanger center piping temperature t2
, the power supply current value i tends to rise, rise, and fall, respectively, compared to the state shown in FIG. Therefore, if the defrosting start determination condition is only the heat mating tube temperature difference value, the defrosting operation will not be started even if frosting progresses if the amount of refrigerant is insufficient.

Here, by appropriately setting the determination point 11 of the power supply current value i, an appropriate defrosting operation can be performed even in such a case.

Next, a case will be described in which the heating operation is started after the defrosting operation is completed, and when the blowing temperature reaches a certain level or higher, the compressor is stopped as is known, and then the heating operation is restarted. That is, when the heating is restarted, the inlet pipe temperature t1 of the indoor heat exchanger 3
is low, and at the same time, the central pipe temperature t2 of the heat exchanger 3 is also low, and there is no difference therebetween. Therefore, the difference temperature setting pipe temperature between the inlet pipe temperature 〇 and the center pipe temperature t2 will be as follows, and a decision on defrosting operation will be made. 6 Therefore, when restarting heating after stopping the compressor, The defrosting operation can be correctly determined by starting the determination after the predetermined time T or more has elapsed while the compressor is in the ON state.

Based on the above explanation, the control circuit shown in FIG. 3 controls the contents of the flowchart shown in FIG. 5.

In step (1) of Fig. 5, it is determined whether the power supply frequency is 60Hz, and in step (2), if it is 60Hz, P
Set 1 boat to Hi, and if it is 50il z, open the P□ port. Specifically, 50/60Hz in Figure 3
The signal from the clock signal generation circuit is discriminated by the 50/60Hz discriminating means in the microcomputer 9, and if the P port on the output side of the microcomputer 9 is 60 Hz, it is set to Hi, and the reference voltage generated by the voltage division of the resistor 15.16 is set. Pull up,
The set pipe temperature t1 is changed by 50/60Hz.

Thereafter, when the heating operation is started in step (3), the microcomputer 9 sets a timer 1- for a predetermined time T1 (step (4)). Since this timer count set is to ensure heating operation for T1 hours (for example, 1 hour) from the start of heating operation, one means is to continue heating for T1 hours, for example. When the timer count is set, it is determined in step (5) that one hour has elapsed, and the heating operation is continued until the T time has elapsed.

Then, when T time has elapsed, the process moves to step (6).

The pipe temperature 11 is read by the pipe temperature detection element 6. Next, the process moves to step (7), where the heat exchanger temperature t2 is read by the heat exchanger temperature detection element 6', and the process moves to step (8), which is the difference temperature set temperature between the pipe temperature t1 and the heat exchanger temperature t2. It is determined whether it is lower than t.

Specifically, the comparator 12 in FIG. 3 makes the determination.

In step (8), if the difference between the pipe temperature and the heat exchanger temperature t2 is higher than the set temperature, step (9)
), the current value is read, and in step (lO) it is determined whether the current value is lower than the set current value. Specifically, the comparator 21 shown in FIG. 3 makes the determination. When the conditions of step (8) or step (10) are satisfied, the process moves to step (11) and defrosting operation is started. That is, the transistors TRI, TR2,
TR3 and TR4 operate respectively, switch the four-way switching valve 2, and if necessary, stop for a certain period of time before that, stop the indoor blower 7 and the outdoor blower 8, and perform defrosting in the cooling cycle. Since the content of this defrosting operation is conventionally well known, detailed explanation will be omitted. Also, return to heating operation (step (1)
2)) can also be implemented by any suitable means as is well known in the art.

Next, when the blowout temperature exceeds a certain level, the compressor stops (
Step (13)) L, compressor restarts (Step (13))
14)) Then, the microcomputer 9 counts the timer count for the predetermined time T2 (step (15)). This timer count set is determined after 12 hours (for example, 1 minute) have elapsed from before returning to heating operation (step (16)).
The heating operation continues until 12 hours have passed. Thereafter, return to step (6) in Figure 5 and repeat the heating and defrosting cycle.

In this embodiment, the defrosting operation is performed by switching from the heating cycle to the cooling cycle.
For example, it goes without saying that a configuration may be adopted in which the heating cycle is maintained and a separately stored refrigerant is flowed to the outdoor heat exchanger, or a configuration in which frost is melted using a separate heat source.

In addition, compressor 1 is in continuous operation when switching to defrosting operation,
The heating operation may be temporarily stopped before returning to the heating operation.

Effects of the Invention As described above, according to the present invention, the temperature of the refrigerant gas in the superheated region is detected at the indoor heat exchanger inlet pipe.

Furthermore, by detecting the refrigerant condensation temperature in the gas-liquid two-phase region at the center of the indoor heat exchanger and knowing the difference in temperature, it is possible to perform appropriate defrosting operation with two temperature detection points or one current detection point. It can be configured very easily. In addition, it is possible to determine whether the refrigerant has sufficient heat for heating operation based on the temperature difference between the inlet side and the center of the indoor heat exchanger.
Since the set temperature is switched at 60Hz, even if the power supply frequency is different, defrosting can be performed by reliably determining whether there is actual heating capacity.Moreover, if the refrigerant in the refrigeration cycle is insufficient, the current Appropriate defrosting can be performed.

Furthermore, in detail, the present invention provides that there is no difference in the temperature of the refrigerant at which frost has formed completely between the inlet part and the central part of the heat exchanger.
Focusing on the fact that the inlet refrigerant temperature is significantly higher than the refrigerant temperature in the center when there is no frost, and the proportional relationship between the difference between the refrigerant temperature on the inlet side and the refrigerant temperature in the center and the power supply current, By detecting the refrigerant temperature, the central refrigerant temperature, and the power supply current, it is possible to obtain large temperature difference changes and current changes from non-frosting to frosting, and with two-point temperature detection and current detection, heating close to the limit can be achieved. You can bring out your abilities. In addition, since frost is not detected until a certain period of time has elapsed from the start of heating, heating capacity is ensured for that certain period of time, and even when the compressor is restarted after being stopped, frost is detected and calmed until a certain period of time has elapsed. Comfort is not compromised either.

[Brief explanation of drawings]

Fig. 1 is a block diagram expressing the defrosting control device of the present invention using function realizing means, Fig. 2 is a refrigeration cycle diagram of an air conditioner showing an embodiment of the present invention, and Fig. 3 is a defrosting control device in an air conditioner. The circuit diagram of the frost control device, Figure 4 shows the temperature of the refrigerant flowing into the indoor heat exchanger, the temperature of the refrigerant in the center of the indoor heat exchanger, the temperature of the refrigerant sucked into the compressor, and the power supply of the air conditioner in the defrost control device. Figure 5 is a flowchart showing the operation of the defrosting control device; Figure 6 is a diagram showing the inlet temperature of the indoor heat exchanger and indoor heat exchange when there is insufficient refrigerant under the above defrosting conditions. FIG. 2 is a characteristic diagram showing the relationship between the difference in temperature at the center of the air conditioner, the temperature of the refrigerant sucked into the compressor, and the power supply current of the air conditioner. 1... Compressor, 2... Four-way switching valve, 3... Indoor heat exchanger, 4... Pressure reducer, 5... Outdoor heat exchanger,
6... Piping temperature detection element, 6'... Central piping temperature detection element of heat exchanger, 9... Microcomputer, 1
0...Storage unit, 11...Drive signal generation means, 12.
21... Comparator, 13.13', 15, 16,
20, 21, 26...Resistor, 17...Current detection element, 18...Current voltage conversion circuit, 25...50/60
Hz clock signal generation circuit, A... outdoor unit, B
... Indoor unit agent Yoshihiro Morimoto Figure F Figure 2 17 - Kirineonishi Figure 4 So, - Koran heat effect Q and distribution change +, - Maruko 1 Ripe poison Q1 Miyako's old gift 1 --- (Sat, -72) Ts --- noj 已・Nijunai 5; S diagram

Claims (1)

[Claims] 1. A control device for switching from a heating cycle to a defrosting cycle in a refrigeration cycle equipped with a compressor, an indoor heat exchanger, a pressure reduction device, and an outdoor heat exchanger is configured to control the time from the start of heating operation of the compressor. a first time measuring means for measuring a preset time, a set time T_1 storage means for storing a preset time, and a time detected by the first time measuring means and a time set in the set time T_1 storage means. a first comparison means for detecting and outputting a coincidence of times; a second time measurement means for measuring the time from restarting the compressor after the compressor is temporarily stopped; and a second time measurement means for storing a preset time. the set time T_2 storage means, the time detected by the second time measuring means, and the set time T_2
A second device that detects and outputs the coincidence of times set in the storage means.
a first temperature detection means for detecting the temperature of a pipe connected to the refrigerant inlet side (during heating operation) of the indoor heat exchanger; and a first temperature detection means connected to the center of the indoor heat exchanger. a second temperature detection means for detecting the temperature of the piping, a set temperature storage means for storing a certain set temperature value for switching the heating cycle to the defrosting cycle, and a 50/6 for inputting the power supply frequency.
0Hz clock input means, 50/60Hz discrimination means for discriminating 50Hz/60Hz, set temperature switching means for switching the boundary value temperature of the set temperature storage means based on an output signal from the discrimination means, and the first temperature detection means. a third comparing means for detecting and outputting that the difference in temperature between the temperature detected by the means and the temperature detected by the second temperature detecting means is lower than the set temperature value stored in the set temperature storage means; a current detection means for detecting a current; a set current storage means for storing a certain set current value for switching a heating cycle to a defrosting cycle; and a set current storage means for storing a current detected by the current detection means in the set current storage means. a fourth comparison means for detecting and outputting a temperature drop below the value, and a comparison between a set time elapsed signal from the first comparison means and a differential temperature value decrease signal from the third comparison means, or the first and second comparisons; determining means for determining whether to switch from the heating cycle to the defrosting cycle based on the set time elapsed signal from the means and the current value drop signal from the fourth comparison means; A defrosting control device for an air conditioner comprising a selection output means for switching control from to defrosting operation.