JPS62233633A - Control device for defrosting of air conditioner - Google Patents

Abstract

PURPOSE:To obtain the heating capacity nearly at its maximum as well as to prevent erroneous operation in defrosting in an air conditioner, by detecting frost freezing on a heat exchanger by detecting the temperature in a refrigerant on the inlet side of an indoor heat exchanger and by detecting the power supply current after a predetermined time has elapsed after starting of an air heating operation, while the air heating operation as well as a specified temp. and current detection are secured. CONSTITUTION:A temperature detector is provided in a pipe at the inlet of an indoor heat exchanger for refrigerating cycle. It detects the temperature in a refrigerant and compares it with a reference temperature of frosting. While the supply current to drive a compressor is detected, and a signal is output in order to change the operation mode into a defrosting operation if the detected current is below a reference value. A decision to control defrosting is not made when the compressor is started and stopped by the ON-OFF operation of a thermostat because a defrosting operation accompanies the thermostat's operation. The air heating operation is changed into defrosting operation when a decision-maker detects frosting after a predetermined time has passed after starting of an air heating operation.

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. Regarding air conditioners.

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, such a conventional configuration requires a plurality of temperature detection elements, complicating the circuit itself. Furthermore, in air conditioners, the amount of air blown indoors is usually set variably, and for this reason, adding a landscape correction means to the conventional technology would further complicate the process. One thing.

Moreover, since this configuration detects the temperature of the gas-liquid mixed refrigerant flowing through the heat exchanger, the temperature change between frost and non-frost is small, and the young uiT flJ can be determined within a minute range. Therefore, there is a problem that the detection accuracy is unstable.

In addition, in recent years, control devices are often configured by using microcomputers to perform complex signal processing, but the fact that there are many input signal sources (temperature detection elements) as in conventional technology makes it difficult to create programs. This is a source of harmful effects, and there are limits to the simplification of programs.As mentioned above, there are many problems with the conventional technology, and improvements are required.

In view of the above-mentioned conventional problems, the present invention provides a defrosting control device that can be simplified in configuration 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. A time measurement means 1 to be measured, a set time T that stores a preset time T1, a storage means, and a match between the time detected by the time measurement means 1 and the time set in the set time T1 storage means. a first comparison means for detecting and outputting the temperature, a temperature detection means for detecting the temperature of the piping connected to the medium inlet side of the indoor heat exchanger in the rJU-recorded room, and a temperature detection means for detecting the temperature of the pipe connected to the medium inlet side of the indoor heat exchanger described in rJU, and a boundary value temperature for switching the heating cycle to the defrosting cycle. a stored set temperature storage means; a second comparison means for detecting and outputting that the temperature detected by the temperature detection means has fallen below a boundary value temperature stored in the set temperature storage means; and a second comparison means for detecting a power supply current. A current detection means, a set current 11 storage means storing a boundary value current 1 for switching the heating cycle to a defrosting cycle, and a current detected by the +'+fJ current detection means are stored in the set current 11 storage means. a third comparison means for detecting and outputting a decrease in the current from the boundary value current set by the current detection means; a set current I2 storage means for storing a preset boundary value current I2; Set current (2) A fourth comparison means for detecting and outputting that the current has fallen below the boundary value current I2 set in the storage means, and a set time T1 elapsed signal from the first comparison means and the fourth comparison means. The set current controller 2 recovery signal and the boundary value lowering signal by the second comparison means or the first
The set time T1 elapsed signal from the comparison means, the set current I2 recovery signal from the fourth comparison means, and the boundary value drop signal from the third comparison means cause the heating cycle to be switched to the defrosting cycle except when the compressor is stopped. and a selection output means for controlling the refrigeration cycle from one heating operation to a defrosting operation in accordance with the output of the determination means.

Effect: With this configuration, 1 support operation is ensured until the predetermined time T1 elapses from the start of the heating operation and until the predetermined current I2 elapses from the start of the compressor by turning on the thermo shut, etc.
After the predetermined time T1 has elapsed, the defrosting operation is controlled based on the temperature detected by the temperature detection means or the current detected by the current detection means.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 2 to 7. 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"fc are connected in sequence. 6 is a pipe temperature detection element, which detects indoor heat during heating. It is attached to the pipe on the refrigerant inlet side of the exchanger 3 (condenser).In this case, during cooling operation, the refrigerant flows in the direction of the solid arrow in the figure, and during heating operation, the four-way switching valve 2 switches. This allows the refrigerant to flow in the direction of the dashed 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, a microcomputer (hereinafter abbreviated as microcomputer) is programmed with the indoor heat exchanger 3 and indoor blower 7, a pipe temperature detection element 6, a current detection element 9 for detecting power supply current, a timer function, a temperature control function, etc. ) is located in the indoor unit (B). Here, the pipe temperature detection element 6 is attached at a location away from the wind circuit where it is not affected by the air blowing from the indoor blower 7. Alternatively, the location may be near the indoor unit B.

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

In the same figure, a microcomputer 11 includes a storage section 12 for storing a quimcount value for determining operating time;
The pivot signal generating means 13 generates an appropriate output signal by comparing the input value with the time value stored in the pivot signal generating means 13. A piping temperature detection element 6 (which is a temperature detection means) is connected to the input side of this microcomputer 110 via a comparator 14.
(for example, a piping thermistor or thermocouple element, etc.) and a temperature setting resistor whose resistance value can be changed as necessary 15.16.
17, a current detection element 9 (for example, a current transformer) that is a current detection means via a comparator 18, a current-voltage conversion circuit 21 that converts a current value into a voltage value, and a current setting whose resistance value can be changed as necessary. Resistors 19 and 20 are connected. Also, on the output side, a switching transistor T R
A relay R1 that drives a four-way switching valve coil, which is a driving means, a relay R2 that drives an indoor blower 7, a relay R3 that drives an outdoor blower 8, and a relay R4 that drives a compressor 1 are connected through T R4. ing.

Here, when comparing the configuration in FIG. 3 with the configuration in FIG. 1, the pipe temperature detection element 6 and the resistor 15 correspond to the temperature detection means in FIG. 1, and the comparator 14 corresponds to the second comparison means in FIG. The voltage generated by the resistors 16 and 17 and the pipe temperature detection element 6 corresponds to the signal of the set current storage means shown in FIG. The comparator 18 corresponds to the first
It corresponds to the third comparison means in the figure, and the voltage generated by the resistors 19 and 20 corresponds to the signal of the set current storage means in FIG. Storage means corresponds to setting current I2 storage means, time measurement means, first comparison means, fourth comparison means, judgment means, and selection output means, among which the drive signal generation means 13 corresponds to judgment means and selection output means. do.

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, the discharge pressure of the compressor 1 is Pd, the suction pressure of the compressor 1 is fPs, and the polytropic index a' (I-nc, where 1 ( When n (in the relationship of K, where K is an adiabatic compression index), the discharge refrigerant temperature Td is expressed by the following equation.

! 1 Td = Ts・(Oath)" Therefore, when the outdoor heat exchanger 5 has not yet had a young frost, the suction refrigerant temperature Ts is high, and the discharge refrigerant temperature Td is also high. Then, as the outside air falls and the frost grows, the suction refrigerant temperature Ts is high. Refrigerant temperature Ts
decreases, and the discharge refrigerant temperature Td also decreases.

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 that is lowered by a predetermined temperature due to heat loss in indoor/outdoor connecting pipes, etc. compared to the discharged gas.

Therefore, as shown in FIG. 4, when the outdoor heat exchanger 5 is not frosted, both the suction refrigerant temperature Ts of the compressor 1 and the inlet pipe temperature t of the indoor heat exchanger 3 are high; As the temperature gradually decreases and frost formation occurs which significantly reduces the heating capacity, the temperature t of the inlet pipe of the indoor heat exchanger 3 extremely decreases.

Further, the power supply current of the air conditioner generally has a value that proportionally follows the discharge refrigerant uL degree Td, and as shown in FIG. 4, it has a value that roughly follows the detected temperature of the pipe temperature detection element 6.

However, the refrigerant [11
When the current value decreases, the current value tends to be relatively low.

That is, if the inlet pipe temperature t becomes less than the set pipe temperature t1, or the current value I becomes less than the set current value 1, the heating capacity decreases, and since frost formation has progressed, it is necessary to defrost.

In this way, the indoor heat exchanger 30 inlet pipe temperature t is the temperature of the refrigerant gas in the superheated region, so it is less affected by the air volume of the indoor blower 7, and the indoor heat exchanger 30 inlet pipe temperature or current value It is possible to make accurate defrosting operation decisions.

Also, compressor operation such as PUMO cut OFF → ON, etc.
When a stop occurs, when restarting the compressor, the compressor suction refrigerant temperature Ts, the indoor heat exchanger 3 inlet pipe temperature t
, power supply current value I each exhibit transient behavior as shown in FIG. Therefore, the set current while the compressor is stopped and after restarting■
By suspending the defrost determination during the period 2, malfunctions in the defrost determination can be prevented.

Next, the behavior when the amount of refrigerant in the refrigeration cycle is insufficient or when refrigerant gradually leaks due to long-term use will be explained using FIG. 6.

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. 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 builds up during heating operation compared to when operating with a steady amount of refrigerant. will proceed. On the other hand, the power supply current decreases compared to steady operation because the amount of refrigerant circulation decreases, which lowers the high pressure and reduces the pressure difference between the high and low pressures, reducing the amount of work of the compressor.

Therefore, the suction refrigerant temperature Ts of the compressor 1 and the power supply current value I of the indoor heat exchanger inlet pipe temperature t1 rise, rise, and fall (approximately), respectively, compared to the state shown in Figure @'4.

Therefore, if the defrosting start determination condition is only the value of the inlet pipe temperature t of the indoor heat exchanger, if the amount of refrigerant is insufficient, the defrosting operation will not start even if the C frost progresses.

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.

In theory B11 of υJ1-, the control plane shown in Figure Chiku3 controls the contents of the flowchart shown in Figure 5.

That is, when the heating operation is started as shown in step 1 in FIG. 5, the microcomputer 11 sets a heater for a predetermined time T1 (step 2). This timer cuff set is for ensuring heating operation for a time T11 (for example, 1 hour) from the start of heating operation, and one means is to forcibly continue heating for 1 hour, for example.

Then, when the timer cacunto is set, step 3
The T1 time elapsed is determined as 'l'lJ. The heating operation is continued until the time T1 has elapsed. Next, in step 4, it is determined whether the compressor is stopped or running, and if the compressor is stopped, it is determined that the compressor is started. Next, in step 5, the compressor start is detected, and in the next step 6, heating operation is ensured from the compressor start, i.e., preventing erroneously entering defrosting operation in the transient situation when the compressor is started. When the compressor is started, the heating operation is continued until the set current (2) is restored. After the current detection at the time of starting the compressor is completed, the process moves to step 8, where the pipe temperature is read by the pipe temperature detection element 6, and the process moves to step 9, where it is determined whether the pipe temperature t is lower than the set pipe temperature t1. It is determined whether Specifically, the comparator 14 in Figure @3 makes the determination.

In step 9, if the pipe temperature t is higher than the set temperature t1, the process moves to step 10, and if the conditions of step 11 are satisfied, the process moves to step 12.If the pipe temperature t is lower than the set temperature t1, the process moves to step 12. The defrosting operation starts. That is, the transistor TR in FIG.
, TR2, TR3, and TR4 respectively operate to switch the four-way switching valve 2, and if necessary, before that, the compressor 1 is stopped for a certain period of time, and the indoor blower 7 and the outdoor blower 8 are stopped. Then defrost using a cooling unit. 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 snow removal operation was 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 a separate heat source is used to melt the frost. Further, the compressor 1 may be operated continuously when switching to defrosting operation, and may be temporarily stopped when returning to heating operation.

Effects of the Invention As described above, according to the present invention, with the above-described configuration, the temperature of the refrigerant gas in the superheated region is detected at the indoor heat exchanger inlet piping, and the power supply current is still detected, so that the influence of the indoor air volume is less affected. It is possible to perform accurate defrosting operation with one point of temperature detection or one point of current detection, without having to be affected by heat, and has a very simple configuration. Since this can be determined based on the inlet side of the indoor heat exchanger and the power supply current value, defrosting can be performed by reliably determining the presence or absence of actual heating capacity. In addition, if there is a shortage of refrigerant in the refrigeration cycle, proper defrosting can be performed using electric current. That is, the present invention focuses on the proportional relationship between the temperature of the refrigerant where frost has completely formed at the inlet of the heat exchanger, the intermediate temperature, and the power supply current, and detects the temperature of the refrigerant at the inlet and the power supply current. As a result, temperature changes and current changes from non-frosting to frosting can be made large, and heating capacity close to the limit can be brought out by detecting temperature and current at one point each.

Furthermore, 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 comfort is not impaired.

In addition, the compressor may stop during heating operation due to BOOMOST 1-OFF, etc., but defrosting judgment is not performed while the compressor is stopped or after starting until the boundary value current is reached, so There is no possibility of defrosting malfunction.

[Brief explanation of drawings]

Fig. 1 is a block diagram expressing the defrosting control device of the present invention as a 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 block diagram of the defrosting control device of the present invention. Fig. 4 is a circuit diagram of the defrosting control device, and a characteristic diagram showing the relationship between the refrigerant temperature flowing into the indoor heat exchanger, the compressor suction refrigerant temperature, and the power supply current of the air conditioner in the same defrosting control device. 5
The figure is a flowchart showing the operation details of the defrosting control device.
Figure 6 is a characteristic diagram showing the relationship between the temperature of the refrigerant flowing into the indoor heat exchanger, the temperature of the compressor suction refrigerant, and the power supply current of the air conditioner when the amount of refrigerant is insufficient in the defrosting control device, and Figure 7 is a characteristic diagram showing the relationship between the refrigerant temperature flowing into the indoor heat exchanger, the compressor suction refrigerant temperature, and the power supply current of the air conditioner in the defrosting control device including the thermostat OFF. 1... Compressor, 2... Four-way switching valve, 3
...Indoor heat exchanger, 4...Pressure reducer,
5...Outdoor heat exchanger, 6...Piping temperature detection element, 7...Indoor blower, 8...
・Outdoor blower, 9...Current detection element, 11...
...Microcomputer, 12...EE
L 13...Drive signal generating means, 14.18
...Comparator, 15.16.17...
...Temperature setting resistor, 19.20...Current setting resistor, 21...Current voltage conversion circuit, A...
...Outdoor unit, B...Indoor unit. )Name embedded Patent attorney Toshi Nakao Male 1/-
- One pressure S formation 2 - Four-way support 3 - 11 Indoor sowing exchanger 4 - 11 Large pressure vessel 5 - 11 Outdoor love box interspersor 6 - Piping easy support qin q -・'Current detection element A - 11 unit E - 11 room 2 unit 61 - Piping inspection and element K - Voltage detection element Hm - Microcomputer 12 - 1 unit S part 13 - -- Signal generation hand No. 3 Figure 74.78- Gonomareta 15, #;, 17.7 De 20-m- Resistor 21--One current to common voltage conversion @T5 -- ERAlt's inhalation 41 Family presentation No. Figure 4 1-・- Power supply 1 -> 5th Figure 1-11 Indoor rejuvenation and central equipment 9
--- 2E cheers and surprises (entering x planning and heating --- heavy water current value? 1 hour.

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 includes a time measuring means for measuring time from the start of heating operation, a set time storage means for storing a preset time, and a time detected by the time measuring means and a memory for the set time. a first comparing means for detecting and outputting the coincidence of times set in the means; a temperature detecting means for detecting the temperature of a pipe connected to the refrigerant inlet side of the indoor heat exchanger; a set temperature storage means that stores a boundary value temperature for switching to the cycle; and a second temperature storage means that detects and outputs that the temperature detected by the temperature detection means has fallen below the boundary value temperature stored in the set temperature storage means.
a comparison means for detecting the power supply current, a current detection means for detecting the power supply current, and a boundary value current I_1 for switching the heating cycle to the defrosting cycle.
a set current I_1 storage means that stores the set current I_1; A set current I_2 storage means that stores the set boundary value current I_2, and a current detected by the current detection means and the set current I_2.
2. A fourth comparing means detects and outputs a decrease from the boundary value current I_2 set in the second storage means, and a set time T_1 elapsed signal from the first comparing means and a set current I_2 from the fourth comparing means. The restoration signal and the boundary value drop signal by the second comparison means, or the set time T_1 elapsed signal by the first comparison means and the set current I_2 restoration signal by the fourth comparison means, and the third comparison. determining means for determining switching from the heating cycle to the defrosting cycle, except when the compressor is stopped, based on a boundary value decrease signal from the means; and controlling the refrigeration cycle from the heating operation to the defrosting operation in accordance with the output of the determining means. A defrosting control device for an air conditioner, comprising a selection output means.