JPS62210336A - Control device for defrosting of air-conditioning machine - Google Patents

Abstract

PURPOSE:To effect defrosting after diciding whether actual heating capacity exists or not surely by a method wherein heating operation is secured until a predetermined time has elapsed after the starting of the heating operation, thereafter, defrosting operation is controlled by the difference in temperatures detected by two sets of temperature detecting means. CONSTITUTION:Heating operation is continued until a time T1, counted by a first timer, has elapsed, thereafter, a second timer counter is set and a compressor 1 is operated continuously for a time T2, for example, then, a temperature (t1) of a pipeline is read by a pipeline temperature detecting element 6 and a temperature (t2) of a heat exchanger is read by a heat exchanger temperature detecting element 6'. A comparator 12 decides whether a temperature difference between the temperatures (t1), (t2) is lower than a set temperature (t) or not and the heating operation is continued until the time T2 has elapsed. During this period, defrosting operation, which satisfies a condition in terms of temperature (t), is started. Transistors TR1.TR2.TR3.TR4 are operated respectively to switch a four-way changeover valve 2 to stop an indoor fan 7 and an outdoor fan 8 and defrosting is effected in cooling 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, snow accretion 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.
When the temperature drops by a certain value from the maximum value (Tc Ta)max, a defrost signal is obtained.
The above correction temperature Tc of the indoor heat exchanger is a correction path to the minimum setting setting, and when the air conditioner is used in a room, dust etc. In other words, the air volume is always lower than the minimum setting of the air conditioner, and the difference between the corrected temperature Tc and the room temperature Ta (Tc - Ta) is the maximum value (Tc - Ta) max.
There are cases where the temperature does not decrease to a certain value even though the outdoor heat exchanger is frosted, and there is a practical problem in that the defrosting operation is not performed even though the outdoor heat exchanger is frosted.

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

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 comparing means for detecting and outputting a coincidence of times detected by the time measuring means; and after the compressor is temporarily stopped;
a second time measuring means for measuring the time from the start of restart and the time at which the temperature detected by the temperature detecting means falls below the boundary value temperature stored in the set temperature storing means; and the second time measuring means a second comparing means for detecting and outputting a coincidence between the time detected by the means and the time detected by the second set time measuring means; and a second comparing means for detecting the temperature of the pipe connected to the refrigerant inlet side of the indoor heat exchanger. a first temperature detection means; a second temperature detection means for detecting the temperature of a pipe connected to a central portion of the indoor heat exchanger; a third time measuring means for measuring a preset time, a third set time storing means for storing a preset time, and a time detected by the third time measuring means and the third set time measuring means. a third comparison means for detecting and outputting the coincidence of the detected times; a set temperature storage means for storing a certain set temperature value for switching the heating cycle to the defrosting cycle; and a temperature detected by the first temperature detecting means. and a fourth comparing means for detecting and outputting a difference temperature between the temperature detected by the second temperature detecting means and the temperature detected by the second temperature detecting means, which is lower than a certain set temperature stored in the set temperature storing means; determining means for determining switching from the heating cycle to the defrosting cycle based on the set time elapsed signal from the comparing means and the differential temperature value decrease signal from the third comparing means; The system includes selection output means for controlling the heating operation to the defrosting operation.

Effect: With this configuration, the heating operation is ensured until a predetermined time has elapsed from the start of the heating operation, and after the elapse of the predetermined time, the defrosting operation is controlled based on the temperature difference detected by the two temperature detection means.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 2 to 5. 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 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 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 8 constitute an outdoor unit A. In addition, an operation control unit (hereinafter referred to as microcomputer) having a microcomputer (hereinafter abbreviated as microcomputer) programmed with the indoor heat exchanger 3 and indoor blower 7, pipe temperature detection elements 6 and 6, a timer function, a temperature adjustment function, etc. (not shown) are provided in indoor units l-H. 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, it may be near indoor unit 1-B.

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

In the same figure, the microcomputer 9 includes a storage unit 10 that stores a time-safe circuit for determining operating time, and a drive signal that generates an appropriate output signal from an AND circuit between the time-safe circuit stored in the storage unit 10 and an input value. There is a generating means 11. On the input side of the microcomputer 9, a comparator 12 is connected to a pipe temperature detection element 6 (for example, a pipe thermistor or a thermocouple element) as a temperature detection means, and a resistor 13 whose resistance value can be changed as necessary. 1, a heat exchanger temperature detection element 6 (for example, a piping thermistor or a thermocouple element, etc.), an arithmetic processing unit 16 that processes signals from a resistor 13' whose resistance value can be changed as necessary, and Resistors 14 and 15 whose resistance values can be changed accordingly are connected. Further, on the output side, there is a relay J that drives a four-way switching valve coil, which is a driving means, through switching transistors TR1 to TR4, a relay R2 that drives the indoor blower 7, a relay R3 that drives the outdoor blower 8, and a compressor 1.
A relay R4 that drives the is connected.

Here, when comparing the configuration in 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.
3 corresponds to the second temperature detection means, the comparator 12 and the arithmetic processing section 16 correspond to the second comparison means in FIG. 1, and the signals produced by the resistors 14 and 15 correspond to the set temperature storage means in FIG. The microcomputer 9 including the storage section 10 corresponds to the set time storage means, time measurement means, determination means, and selection output means in FIG. It corresponds to the 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.

When the suction pressure of compressor 1 is PII and the polytropic index is n (where 1 < n < K, K is the adiabatic compression index), the discharge refrigerant temperature Td is calculated using the following formula: % Formula % Therefore, outdoor heat exchange When the container 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. The temperature is a predetermined temperature lower than that of the discharged gas due to heat loss in internal and external connecting pipes, etc. In addition, the heat exchange gFr temperature detection element 6
is provided almost in the center of the indoor heat exchanger 3, and the compressor 1
This is the part through which the refrigerant gas discharged from the refrigerant gas at high temperature and island pressure flows, and the discharged refrigerant gas changes from the gas phase to the gas-liquid two-phase state and then to the liquid phase, but its temperature is considered to be almost constant.
This is generally called the condensation temperature. The relationship between the temperature of the inlet pipe of the heat exchanger 3 and the condensation temperature is such that when the refrigerant gas discharged from the compressor 1 flows into the heat exchanger 3 in a gas state with a small superheated region, the temperature difference is It's getting less. Therefore, as shown in FIG. 4, when the outdoor heat exchanger 5 is not struck by lightning, the suction refrigerant temperature Ts of the compressor 1, the inlet pipe temperature t1 of the indoor heat exchanger 3, and the The pipe temperatures t2 are both high, and gradually decrease 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, and at the same time, The central piping temperature t2 of the heat exchanger 3 also decreases, the difference disappears, and the temperatures progress to almost the same state. 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 affected by the air volume of the blower 7, and the temperature t2 of the central pipe of the heat exchanger 3 is is stable because it detects the condensation temperature, and the temperature difference t
By measuring 1-t2, it is possible to accurately determine defrosting operation.

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

The microcomputer 9 counts a predetermined time T (step 2). This timer count set is for ensuring heating operation for T1 hours (for example, 1 hour) from the start of heating operation, and one means is to continue heating for T1 hours, for example.

When the first timer count is set, it is determined in step 3 whether time T1 has elapsed. The heating operation is continued until the time T1 has elapsed.

Then, when the time T1 has elapsed, the process moves to step 4, where a second timer counter is set, and the process moves to step 5, where it is determined in the microcomputer 9 whether or not the compressor 1 is operating. If no operation is being performed (if step 5 is not satisfied), the process goes to step 4 and the second timer counter is reset.

Next, when the conditions of step 5 are satisfied, step 6 and 7
It is determined that two hours (for example, four minutes) have passed.

After the compressor 1 has been continuously operated for 12 hours, the process moves to step 7, where the pipe temperature detection element 6 reads the pipe temperature t1. Next, in step 8, the heat exchanger temperature t2 is read by the heat exchanger temperature detection element 6, and in step 9, it is determined in the microcomputer 9 whether or not the compressor 1 is operating. If no operation is being performed, the process returns to step 4 and the second timer counter is reset. Further, in step 1°, 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.

Then, when the condition of step 11 is satisfied, it is determined in step 11 that three hours have elapsed. Heating operation continues until 13 hours have passed. Furthermore, if the pipe temperature t becomes higher than the set pipe temperature t1 before 13 hours have elapsed, the process returns to step 7 and the third timer count is reset.

Then, when the conditions of step 11 are satisfied, step 12
The defrosting operation starts. That is, the transistors TR1, TR2, TR3, and TR4 shown in FIG. 3 operate, respectively, to switch the four-way switching valve 2, and if necessary, stop the operation for a certain period of time beforehand, thereby stopping 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.

Further, the restoration of the heating operation can be carried out by any suitable means as is well known in the art.

In this embodiment, the defrosting operation is performed by switching from the heating cycle to the cooling cycle. ta f
rL
-i- It goes without saying that it is also possible to use a configuration in which a refrigerant that has been separately stored in heat is passed into the outdoor heat exchanger, or a configuration in which a separate heat source is used to melt the lightning. 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, it is possible to perform accurate defrosting operation with two temperature detection points. Since it is possible to determine whether there is sufficient heating capacity based on the temperature difference between the inlet side and the center of the indoor heat exchanger, defrosting can be performed by reliably determining the presence or absence of actual heating capacity. .

In other words, in the present invention, there is no difference in the temperature of the refrigerant between the inlet part and the center part of the heat exchanger when snow is completely covered, and the inlet refrigerant temperature is higher than the refrigerant temperature in the center part when there is no snow. By focusing on the point that is significantly higher than the temperature at the inlet side and detecting the refrigerant temperature at the center, it is possible to obtain a large temperature difference change from unfrosted to 72m, and the temperature detection at two points is the limit. It is possible to draw out heating capacity close to . In addition, the present invention does not detect N frost until a certain period of time has elapsed from the start of heating, and does not detect snow accumulation until a certain period of time has elapsed from the start of restart of operation after the compressor is temporarily stopped during heating operation.
For example, immediately after the compressor is restarted at 70FF, the temperature of the indoor heat exchanger piping is detected while it is rising, and the defrosting operation is not accidentally started even though there is no frost.
Furthermore, since the defrosting operation is not started unless the pipe temperature of the indoor heat exchanger continuously falls below the set temperature, the pipe temperature may be detected to be lower than the actual temperature due to noise etc.
Defrosting operation will not be started by mistake.

[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 simple 2-air 1-air diagram. Figure 4 is a circuit diagram of the defrost control device in the harmonizer, and shows the temperature of the refrigerant flowing into the indoor heat exchanger, the refrigerant temperature in the center of the indoor heat exchanger, and the compressor suction refrigerant temperature in the defrost control device. A characteristic diagram showing the relationship, and FIG. 5 is a flowchart showing the operation details of the defrosting control device. 1... Compressor, 2... Four-way switching valve, 3
...Indoor heat exchanger, 5...Outdoor heat exchanger, 6...Piping temperature detection element, 6...
...Central pipe temperature of heat exchanger, 9...Microcomputer, 10...Storage section, 11...
...Drive signal generating means, 12...Comparator, 13, 13, 14, 15...Resistor, A...
...Outdoor unit, B...Indoor unit. Name of agent: Patent attorney Toshi Nakao, 1 person, 5-
Outdoor side number & exchanger E-Indoor unit 2nd diagram - Microcomputer H-11 cantering number generating means ts, 13t/4. ts -Resistor 16- Arithmetic processing section Fig. 3 Fig. 4 Time -→

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 first set time storage means; a second time measurement means for measuring the time when the temperature has decreased below the stored boundary value temperature; and a second set time storage means for storing the preset time;
The time detected by the second time measuring means and the second
a second comparison means for detecting and outputting the coincidence of the times set in the set time storage means of the compressor; and a third time measurement means for measuring the time from the restart of operation of the compressor after the temporary operation stop of the compressor. A third set time storage means that stores a preset time, and a match between the time detected by the third time measurement means and the time set in the third set time storage means is detected and output. a third comparison means for detecting the temperature of the piping on the refrigerant inlet side of the indoor heat exchanger; and a first temperature detection means for detecting the temperature of the piping connected to the central portion of the indoor heat exchanger. a second temperature detection means, a set temperature storage means that stores a certain set temperature value for switching the heating cycle to a defrosting cycle, and a temperature detected by the first temperature detection means and a temperature detected by the second temperature detection means. fourth comparison means for detecting and outputting that the difference with the temperature has fallen below a certain set temperature stored in the set temperature storage means;
a determining means for determining switching from a heating cycle to a defrosting cycle based on a set time elapsed signal from the first, second and third comparing means and a differential temperature value decrease signal from the third comparing means; A defrosting control device for an air conditioner comprising a selection output means for controlling the refrigeration cycle from heating operation to defrosting operation according to the output.