JPS62213637A - Defrost control device for air conditioner - Google Patents

Abstract

PURPOSE:To provide a positive operation by a method wherein a defrost operation is controlled when a desired time is elapsed after a starting time of heating operation by a difference in sensed temperatures of two temperature sensing means or a sensed electrical current of an electrical current sensing means and after a desired time from a reoperation of a compressor is elapsed. CONSTITUTION:When a heating operation is started, a timer count of a desired time T is counted by a microcomputer 9 and then a heating operation is continued. After the time T is elapsed, an inputting of a piping temperature (t1) by a piping temperature sensing element 6 and an inputting of a heat exchanging temperature (t2) by a heat exchanger temperature sensing element 6' are performed. A comparator 12 may judge if a temperature difference between (t1) and (t2) is lower than the set temperature (t) and in the case that a value of (t1-t2) is higher than the set temperature, a comparator 18 may judge if the electrical current value I is lower than the set electrical current I1. If the condition of t>=t1-t2 or I<=I1 is fulfilled, each of the transistors TR1, TR2, TR3, TR4 is operated, a four-way changing-over valve 2 is changed over and a frost removing operation is carried out in a refrigerating cycle.

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. This relates to an air conditioner.

BACKGROUND ART Conventionally, as shown in Japanese Patent Publication No. 59-34255, the state of frost on an outdoor heat exchanger is detected based on both the temperature change of the indoor heat exchanger and the indoor temperature change. Technologies have been developed to control heating and defrosting operations.

Problems to be Solved by the Invention However, in this conventional configuration, the difference (Tc-Ta) between the corrected temperature Tc of the indoor heat exchanger and the indoor temperature Ta is more constant than its maximum value (Tc-Ta)max. When the value decreases, a defrost signal is obtained, but the corrected temperature Tc of the indoor heat exchanger is a corrected value up to the minimum set air volume, and if the air conditioner is used in the room. In this case, the filter installed in front of the indoor heat exchanger is usually clogged with dust and the air volume is lower than the minimum setting of the air conditioner, and the difference between the corrected temperature Tc and the indoor temperature Ta (Tc
-Ta) may not decrease by a certain value from its maximum value (Tc-Ta)max, which may cause practical problems such as not performing defrosting operation even though the outdoor heat exchanger is frosted. There's a problem.

In view of the above-mentioned conventional problems, the present invention provides a defrosting control device that can ensure reliable operation without sacrificing the advantages of the conventional technology.

Means for Solving the Problems In order to solve the above problems, the present invention provides a control device that controls the refrigeration cycle from the heating cycle to the defrosting cycle as shown in FIG. a first time measuring means for measuring the time from , a first set time storage means for storing a preset time, and a time detected by the first time measuring means and the first setting. a first comparison means that detects and outputs the coincidence of times set in the time storage means; and a first temperature detection means that detects the temperature of the pipe connected to the refrigerant inlet side of the indoor heat exchanger during heating operation. , a second temperature detection means for detecting the temperature of the pipe connected to the central part of the indoor heat exchanger; a set temperature storage means for storing a certain set temperature value for switching the heating cycle to the defrosting cycle; a second comparison that detects and outputs that the difference between the temperature detected by the first temperature detection means and the temperature detected by the second temperature detection means has fallen below a certain set temperature stored in the set temperature storage means; a current detection means for detecting a power supply current; a set current storage means for storing a boundary value current for switching a heating cycle to a defrosting cycle; and a current detected by the current detection means is stored in the set current storage means. a third comparison means that detects that the current has decreased below the set boundary value current and outputs it; a second time measurement means that measures the time from the start of heating restart after the compressor is stopped; and a preset time. and a fourth comparison for detecting and outputting a match between the time detected by the second time measuring means and the time set in the second set time storing means. and a set time elapsed signal by the first comparing means and a differential temperature value decrease signal by the second comparing means, or a set time elapsed signal by the first comparing means and a boundary value decrease by the third comparing means. a determining means for determining switching from the heating cycle to the defrosting cycle based on the signal and a set time elapsed signal from the fourth comparing means; and a determining means for switching the refrigeration cycle from the heating operation to the defrosting operation in accordance with the output of the determining means. It is composed of a selection means for controlling.

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 elapses, the detected temperature difference between the two temperature detecting means, the detected current of the current detecting means, and the compressor are restarted. The defrosting operation is controlled after a predetermined period of time has passed since the operation.

EXAMPLE OF REAL BLOOD Hereinafter, one embodiment 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 the same figure, the refrigeration cycle includes compressor 1
, a four-way switching valve 2, an indoor heat exchanger a, 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 at the center of the indoor heat exchanger and detects the refrigerant temperature at the center of the heat exchanger.

In this case, during cooling operation, the refrigerant flows in the direction of the solid line arrow in the figure, and during heating operation, the four-way switching valve 2 is switched so that the refrigerant flows in the direction of the broken line arrow in the figure. Furthermore, the compressor 1, the four-way switching valve 2, the pressure reducer 4,
The outdoor heat exchanger 5 and the outdoor blower 8I constitute an outdoor unit A. In addition, the indoor heat exchanger 3
and indoor blower 7, and pipe temperature detection elements 6 and 6'
, an operation control section (not shown) having a microcomputer (hereinafter referred to as microcomputer) programmed with a current detection element 17 for detecting the power supply current, a timer function, a temperature control function, etc. is provided in the indoor unit B. There is.

Here, the pipe temperature detection element 6 is attached at a location away from the ventilation circuit where it is not affected by the air blowing from the indoor blower 7. Alternatively, the location may be near indoor unit B.

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

In the figure, the microcomputer 9 includes a storage section 10 that stores a time count value for determining the operating time, and a drive signal generator that generates an appropriate output signal by comparing the time count value stored in the storage section 10 with an input value. There are a storage section 10 for storing a timer count value for determining the re-operation time and a drive signal generation means 11 for generating an appropriate output signal by comparing the timer count value stored in the storage section 10 with an input value. A pipe temperature detection element 6 serving as a temperature detection means is connected to the input side of the microcomputer 9 via a comparator 12.
(for example, a piping thermistor or thermocouple element, etc.) and a resistor 13 whose resistance value can be changed as necessary.
temperature detecting means, a heat exchanger temperature detecting element d (for example, a piping thermistor or a thermocouple element, etc.), an arithmetic processing unit 16 that processes the signals of the resistor 13' whose resistance value can be changed as necessary, and as necessary. Resistor 1 whose resistance value can be changed by
4°15 is connected. A current detection element 17 (for example, a current transformer) as a current detection means and a current-voltage conversion circuit 2 that converts a current value into a voltage value via a comparator 18
1 and a current setting resistor 19 whose resistance value can be changed as necessary.
．． 20 are connected.

In addition, on the output side, switch transistors TR1 to TR
4, a relay R1 drives a four-way switching valve coil, which is a driving means, a relay R2 drives an indoor blower 7, a relay drives an outdoor blower 8, and the configuration shown in FIG.
Comparing the configurations of , pipe temperature detection element 6 and resistor 1
3 is used as the first temperature detection means in FIG. The voltage generated by the resistors 14 and 15 is used as the signal of the set temperature storage means shown in FIG. 1, the current detection element 17 and the current voltage conversion circuit 21 are used as the current detection means shown in FIG. The third comparison means in the figure includes a resistor 19.
・The voltage generated by 20 corresponds to the signal of the set current storage means shown in FIG. 1, and the microcomputer 9 including the storage section 10 corresponds to the set time storage means, time measurement means, determination means, and selection output means shown in FIG. Among them, the drive signal generating means 11 is a determining means,
This corresponds to 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 compressor 1 is Ps, and the polytropic index is n
(where 1 < n < k, where k is the adiabatic compression index), the discharge refrigerant temperature Td is expressed by the following formula. 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. Then, as the outside air drops and frost grows, the suction refrigerant temperature Ts decreases, and 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 in the present invention 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. is a temperature lower than that of the discharged gas by a predetermined temperature due to heat loss in internal and external connecting pipes, etc. The heat exchanger temperature detection element d is provided almost in 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. Although this is the part that changes from a two-phase gas phase to a liquid phase, its temperature is considered to be approximately constant and is generally referred to as the condensation temperature. Furthermore, the relationship between the temperature of the inlet pipe of the heat exchanger 3 and the condensation temperature is the same as that of the compressor 1.
When the refrigerant gas discharged from the refrigerant gas flows into the heat exchanger 3 in a gas state with less superheated region, the temperature difference becomes smaller. Therefore, as shown in FIG. 4, when the outdoor heat exchanger 5 is not frosted, the suction refrigerant temperature Ts of the compressor 1, the inlet pipe temperature t1 of the indoor heat exchanger 3, and the center of the heat exchanger 3 are The pipe temperature t2 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 t1 of the indoor heat exchanger 3 drops extremely. At the same time, the central piping temperature t2 of the heat exchanger 3 also decreases, the difference disappears, and the temperatures proceed to almost the same state. In addition, the power supply current of the air conditioner generally follows the discharge refrigerant temperature Td in proportion. When the amount of refrigerant in the refrigeration cycle of the air conditioner decreases, the current value tends to be relatively low. That is, if the difference temperature t between the inlet pipe temperature t1 and the center pipe temperature t2 becomes less than the set pipe temperature, the heating capacity decreases and frost formation has progressed, so it is necessary to defrost. In this way, the inlet pipe temperature t1 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 central pipe temperature t2 of the heat exchanger 3 is the temperature of the refrigerant gas in the superheated region. Since the temperature is detected, it is stable, and by measuring the temperature difference t1 - t2, it is possible to make an appropriate decision on defrosting operation.

Next, the behavior when the amount of refrigerant in the refrigeration cycle is insufficient, when the refrigerant gradually leaks due to long-term use, and when the compressor is restarted after stopping will be explained using FIG. As is well known, when the amount of refrigerant is insufficient compared to the steady amount of refrigerant, the amount of refrigerant circulating within the refrigeration cycle decreases, the temperature of the refrigerant discharged from the compressor increases, and the temperature of the suction refrigerant also increases. do.

Furthermore, the temperature difference between the two also increases. On the other hand, in the refrigeration cycle, the pressure naturally decreases, and the refrigerant temperature in the evaporator also decreases with the pressure decrease, and due to heat exchange with the outside air, frost formation is less likely during heating operation than during constant refrigerant flow operation. We will move on. On the other hand, the power supply current decreases compared to steady operation because the amount of refrigerant circulation decreases, the high pressure decreases, and the difference between the high and low pressures becomes smaller, reducing the amount of work of the compressor. Therefore, the suction refrigerant temperature T of compressor 1
111 The difference Δt1 between the indoor heat exchanger inlet temperature t1 and the indoor heat exchanger center pipe 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 exchanger pipe temperature difference value, if the amount of refrigerant is insufficient, the defrosting operation will not start even if the defrosting progresses.

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 finished, and when the Suita temperature exceeds a certain 1 yen, the compressor stops 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 temperature difference t between the inlet pipe temperature t1 and the center pipe temperature t2 makes the set pipe temperature less than or equal to the setting value, and a defrosting operation is determined.

Therefore, when the heating is restarted after the compressor is stopped, the defrosting operation can be correctly determined by starting the determination after a predetermined time T or more has elapsed during the compressor ON state.

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

That is, when the heating operation is started as shown in step 1 of FIG. 5, the microcomputer 9 counts a timer count for a predetermined time T (step 2). This timer count set is also used for heating operation.

And once the timer count is set, step 3
It is determined that one hour has passed. Heating operation continues until one hour has passed.

After seven hours have elapsed, the process moves to step 4, where the pipe temperature detection element 6 reads the pipe temperature t1. Next, the process moves to step 5, where the heat exchanger temperature t2 is read by the heat exchanger temperature detection element d, and step 6
Moving on, it is determined whether the temperature difference between the pipe temperature t1 and the heat exchanger temperature t2 is lower than the set temperature t. Specifically, the comparator 12 in FIG. 3 makes the determination. If in step 6 the difference between the pipe temperature t and the heat exchanger temperature t2 is higher than the set temperature, the process moves to step 7 and it is determined whether the current value I is lower than the set current value 11. Specifically, the comparator 18 shown in FIG. 3 makes the determination.

When the conditions of step 6 or step 8 are satisfied, the process moves to step 9 and defrosting operation is started. That is,
Transistors TR1, TR2, TR3, TR4 in Figure 3
operate respectively, switch the four-way selector valve 2, and if necessary, stop for a certain period of time before that to stop the indoor blower 7 and the outdoor blower 8. Then, defrost is performed in the cooling cycle.

Since the content of this defrosting operation is conventionally well known, detailed explanation will be omitted. Furthermore, the restoration of the heating operation (step 10) can be carried out by any suitable means, as is well known in the art. Next, when the blowing temperature exceeds a certain level, the compressor stops (step 11), and when the compressor restarts (step 12), the microcomputer 9 counts a predetermined time T.

This timer count sector is 7 from before returning to heating operation.
The determination is made after a period of time (for example, 1 minute) has elapsed.

Heating operation continues until one hour has passed. After that, return to step 4 in Figure 5 and repeat the heating and defrosting cycle.

In this embodiment, it goes without saying that the defrosting operation may be performed by switching from the heating cycle to the cooling cycle, or the frost may be melted using a side heat source. Further, the compressor 1 may be operated continuously when switching to defrosting operation, and may be temporarily stopped before returning to heating operation.

Effects of the Invention As described above, according to the present invention, with the above configuration, the refrigerant gas temperature in the superheated region is detected at the indoor heat exchanger inlet piping, and the refrigerant condensation temperature in the gas-liquid two-phase region is detected in the indoor heat exchanger. By detecting the temperature difference in the center of the exchanger, you can perform accurate defrosting operation with two temperature detection points or one current detection point.
The configuration is very simple, and whether or not the refrigerant has enough heat for heating operation can be determined based on the temperature difference between the inlet side and the center of the indoor heat exchanger, so the actual heating capacity can be determined. Defrosting can be performed by reliably determining the presence or absence of In addition, when the refrigerant in the refrigeration cycle is insufficient, appropriate defrosting can be performed using electric current.

This is due to the fact that the inlet refrigerant temperature is significantly higher than the refrigerant temperature at the center when there is no frost, and the proportional relationship between the difference between the refrigerant temperature at the inlet and the center and the power supply current. By detecting the refrigerant temperature in the central part and the refrigerant temperature and electric current, it is possible to obtain a large temperature difference change and current change from non-frosting to frosting, and it is possible to reach the limit with two points of temperature detection and current detection. It is possible to draw out similar heating capacity. Since the present invention does not detect frost formation until a certain period of time has elapsed from the start of heating, the heating capacity is ensured for that certain period of time, and even when restarting the compressor after stopping, frost formation is not detected until a certain period of time has elapsed. Therefore, comfort is not compromised.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the defrosting control device of the present invention expressed as a means for realizing cooling, Fig. 2 is a refrigeration cycle diagram of an air conditioner showing an embodiment of the present invention, and Fig. 3 is a diagram of the refrigeration cycle of an air conditioner according to an embodiment of the present invention. A circuit diagram of the defrosting control device in the machine, a characteristic diagram showing the relationship between the temperature of the medium, the temperature of the compressor suction refrigerant, and the power supply current of the air conditioner, and the fifth
The figure is a flowchart showing the operation of the same jumping control device.
The figure shows the relationship between the difference between the inlet temperature of the indoor heat exchanger and the temperature at the center of the indoor heat exchanger, the compressor suction refrigerant temperature, and the power supply current of the air conditioner when there is insufficient refrigerant under the same defrosting conditions. It is a diagram. 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, 18... Comparator, 13.1
3'・14・15・19・20・・・Resistance, 17
... Current detection element, 21 ... Current voltage conversion circuit, A ... Outdoor unit, B ...
・Indoor unit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure/- Single pressure V & machine 2 - Four-way switching valve J - Indoor heat exchanger 4 - Pressure reducer 5 -. 1! l + Side school Bunsuteki 6- Piping wet water & $ Mugiko 6'--1 Final alternator warm detection Nako/7--Kaku flow detection terminal 6- Piping temperature detection element 13, 13', /4.1
5. /9.20- wasted 6' ---Thermographic clamp temperature detection element /4 -m- Arithmetic processing section? -m- Microcomputer /7 -1 Current detection element Figure 4 Time □ Ts -m = Compressor f) Suction flow rate L I Temperature of the inlet piping of the exchanger - Temperature of the central piping of the indoor heat absorber Pressure #! ! 1 machine Q inhalation temperature i - m - electric current complex

Claims (1)

[Claims] A refrigeration cycle equipped with a compressor, an indoor heat exchanger, a pressure reducing device, and an outdoor heat exchanger is provided with cycle switching means for switching between a heating cycle and a defrosting cycle, and the cycle switching means is configured to switch between a heating cycle and a defrosting cycle. A control device for switching to a cycle is controlled by a first time measuring means for measuring time from the start of heating operation of the compressor, a first set time storage means for storing a preset time, and a first set time storage means for storing a preset time; a first comparing means for detecting and outputting a match between the time detected by the time measuring means and the time set in the second set time storage means; a first temperature detection means for detecting the temperature of the connected pipes; a second temperature detection means for detecting the temperature of the pipe connected to the central part of the indoor heat exchanger; A set temperature storage means stores a certain set temperature value to be switched to, and a temperature difference between the temperature detected by the first temperature detection means and the temperature detected by the second temperature detection means is stored in the set temperature storage means. a second comparing means for detecting and outputting a temperature drop below a certain set temperature; a current detecting means for detecting a power supply current; and a set current storing means for storing a boundary value current for switching a heating cycle to a defrosting cycle; a third comparison means for detecting and outputting that the current detected by the current detection means has decreased due to a boundary value current stored in the set current storage means; and a third comparison means for detecting and outputting a decrease in the current detected by the current detection means, and a time elapsed from restarting the compressor after stopping the compressor. a second time measurement means for measuring, a second set time storage means for storing a preset time, and a time detected by the second time measurement means and the second set time storage means; a fourth comparison means for detecting and outputting a coincidence of set times, and a set time elapsed signal from the first comparison means and a temperature difference value decrease signal from the second comparison means, or the first comparison means determining means for determining switching from the heating cycle to the defrosting cycle based on the set time elapsed signal from the third comparing means, the boundary value decrease signal from the third comparing means, and the set time elapsed signal from the fourth comparing means; A defrosting control device for an air conditioner comprising selection output means for controlling the refrigeration cycle from heating operation to defrosting operation according to the output of the determination means.