JPH0684831B2 - Defroster for air conditioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a defrosting device for an air conditioner such as an electric heat source heat pump machine.

(Prior Art) In a conventional defrosting device, a predetermined time, for example, 60 minutes has elapsed irrespective of the rate of decrease in capacity, and the coil fin temperature from the defrosting commander is, for example, -5 ° C or less and defrosting is performed. Defrost (defrosting) was started by the command signal being sent, but since it was defrosting regardless of the decrease rate of heating capacity, the capacity decrease often becomes large. Energy efficiency ratio (EER) was low due to poor heating efficiency.

In order to improve such a point, the present applicant has previously proposed a defroster for an air conditioner for performing defrosting at an optimum defrosting timing by applying for Japanese Patent Application No. 61-207360.
Application filed on March 2).

In the above application, the heating capacity from the start of the heating operation immediately after the end of defrosting in the usage-side coil during the heating operation is converted into the heated fluid temperature difference between the outlet and the inlet of the usage-side coil at regular time intervals. The cumulative heating capacity value is calculated by dividing the cumulative heating capacity value by the sum of the operation time of the defrosting operation performed immediately before the heating operation and the subsequent heating operation time. The present invention relates to a defrosting device that compares the calculated current heating value with the previous value and outputs a defrosting signal when the current value is small.

(Problems to be Solved by the Invention) In the contents of the above-mentioned application, since the decrease in the heating capacity is judged by the decrease in the temperature difference between the use side coils, it is necessary to compare the magnitude of the temperature difference between this time and the previous time. For example, the rate of change can be determined, and it is not necessary to strictly calculate the heating capacity itself, but this is based on the assumption that the flow rate of the heated fluid such as the air flow or the capacity of the compressor is constant. However, in the case of an operation mode in which the air volume changes, it is not possible to cope with it as it is, and it is equipped with a variable blower fan to change the air volume automatically or manually during heating operation as in recent years, Separate measures must be taken in the case of an air conditioner whose capacity can be automatically adjusted according to the load.

In order to address such a problem, the present invention, in addition to the control method for achieving the EER improvement in the previous application, changes the flow rate of the heated fluid flowing through the utilization side coil, and also changes the capacity of the compressor. The present invention has been devised to provide an improved defrosting device equipped with a control system capable of coping with heating operation modes as well. Thus, the defrosting operation is properly started, and the operation is performed by maintaining the maximum EER value. The purpose is to improve economy and maintain a comfortable environment by stabilizing the temperature of conditioned air.

(Means for Solving Problems) Therefore, as shown in FIG. 1, the present invention provides a defrosting device for an air conditioner, which is a temperature difference calculating means (1), a temperature difference correcting means (2), and a temperature difference integrating means. (3), an average heating capacity calculation means (4) and a comparison means (5) are provided, wherein the temperature difference calculation means (1) is heated in the utilization side coil (10) during heating operation. Temperature difference (ΔT _n ) from fluid outlet temperature (T _o ) and inlet temperature (T _i ) at regular intervals
Is calculated and stored.

On the other hand, as for the temperature difference correction means (2), by performing the comparison between the temperature difference calculating means (1) a temperature difference previous temperature difference each time the calculated ([Delta] T _n) ([Delta] T _n-1), the When the absolute value of the difference is larger than the predetermined value, the ratio between the previous temperature difference (ΔT _n-1 ) and the current temperature difference (ΔT _n ) is calculated as the correction coefficient (a), and the temperature difference calculating means is also used. Each temperature difference (ΔT _n ) after this time calculated by (1) is multiplied by the correction coefficient (a) to correct the temperature difference (ΔT ′ _n ) corresponding to the operating state before the previous temperature difference calculation. Have a configuration.

Next, the temperature difference integrating means (3) is connected to the temperature difference calculating means (1).
Is calculated, and the temperature difference integrated value (S) is calculated and stored from the temperature difference values corrected by the temperature difference correction means (2) from the start of the heating operation immediately after the end of defrosting as a base point. Have.

The average heating capacity calculation means (4) uses the temperature difference integrated value (S) calculated by the temperature difference integration means (3) as the operation time (td) of the defrosting operation performed immediately before the heating operation. The average heating capacity (Q _m ) is calculated and stored by dividing the sum by the subsequent heating operation time (ti).

Further, as for the comparing means (5), the current heating value and the previous heating value of the average heating capacity (Q _m ) calculated by the average heating capacity calculating means (4) are compared with each other, and when the current value is small, they are excluded. It has a configuration for outputting a frost signal.

As the fluid to be heated, air or water corresponds to this depending on the type of the utilization side coil (10), and the flow rate is controlled by controlling the capacity of the fan or pump.

(Operation) In the present invention, the average heating capacity calculation means (4) and the comparison means (5)
By capturing the time when the average heating capacity (Q _m ) reaches a peak by using, and when defrosting is required at this time, defrosting is performed. When the capacity control is performed, the temperature difference correction unit (2) calculates the temperature difference (Δ
Since T _n ) is corrected so as not to be affected by fluctuations due to flow rate switching and compressor capacity control, the heating capacity can be calculated in accordance with the actual situation and proper defrost timing can be taken.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a device circuit diagram of an air conditioner according to an embodiment of the present invention, which includes a compressor (6), a four-way switching valve (7), a heat source side coil (8), a capillary tube (9), and a use side. A well-known refrigeration circuit is configured by the coil (10) and the accumulator (11), and during heating operation, the refrigerant is circulated in the direction indicated by the solid line so that the utilization side coil (10) becomes a condenser and a heat source side coil ( 8) to act on the evaporator, respectively. On the other hand, during the cooling operation and the defrosting operation, the refrigerant is circulated in the direction of the broken line arrow so that the heat source side coil (8) is connected to the condenser and the utilization side coil ( It is needless to say that the refrigerant flow direction is switched by the switching operation of the four-way switching valve (7), and in the case of defrost operation, the heat source side fan (14) is operated. ) And the user side fan (15) together. It is intended Mel.

In FIG. 2, (12) is a first temperature detector for detecting the air temperature (T _o ) at the outlet of the utilization side coil (10), (1
3) also shows the second temperature detectors for detecting the air temperature (T _i ) at the inlet, respectively, and both temperature detectors (12), (13)
Constitutes an input element of the temperature difference calculating means (1).

On the other hand, (16) is a deicer that detects the coil inlet temperature of the heat source side coil (8), which becomes an evaporator during heating operation, and is below -5 ° C, or the built-in timer measures the heating operation time. It is a known defrost detector that issues a defrosting required signal depending on whether two hours have passed, and is connected to the input end of the defrost command means.

An electronic control circuit for controlling defrosting of the air conditioner having the above configuration is as schematically shown in FIG. 3, and (17) is a well-known microcomputer, which includes a CPU (18), a RAM (19) and
The ROM (20) is a basic element.

A program for controlling the CPU (18) is written in the ROM (20), and the CPU (18) fetches external data from the input port (21) or RAM (1
9) Performs arithmetic processing while exchanging data with, and outputs the processed data to the output port (22) as needed.

The output port (22) receives the output port designation signal from the CPU (18), temporarily stores the data in the port, and outputs the analog signal to the four-way switching valve (7) via the D / A converter (26). It outputs to the solenoid (7 _S ) and the motor (15 _M ) of the fan (15) on the user side.

On the other hand, when the input port (21) receives the input port designating signal from the CPU (18), it takes in necessary information to the port, and the utilization side coil (1
Air outlet temperature (T _o ) at 0) is A / D converter (23)
Via the A / D converter (24) as a digital signal, the air inlet temperature (T _i ) as a digital signal, and the coil inlet temperature of the heat source side coil (8) detected by the deicer (17) is A / It is output to the input port (21) as a digital signal through the D converter (25).

Then, the program control in the microcomputer (18) is performed by the temperature difference calculating means (1), the temperature difference correcting means (2), the temperature difference integrating means (3), the average heating capacity calculating means (4) and the comparing means ( 5) and the defrosting instruction means, and the program written in the ROM (20) is shown in a flowchart of FIG.

Here, the theoretical basis for properly setting the timing of the defrosting start timing in the present invention will be described with reference to the diagrams starting from FIG. 5, but the way of determining the defrosting start timing is the use side coil during heating. Average heating capacity in (10),
That is, the average heating capacity of the air conditioner is greatly affected.To improve the EER, the average heating capacity, that is, the average heating capacity from the start of the defrosting operation to the start of the next defrosting operation. the value mUST be satisfied condition may be a maximum value, an air heat source, the average heating capacity when stopping the usage-side fan (15) in an air conditioner of an air utilization system during defrosting (Q _m) is the following It becomes an expression.

However, ΔT _m : Average temperature difference (℃) t _h : Heating operation time (H _r ) C _p : Air specific heat (Kcal / kg ・ ° C) r: Air specific weight (kg / m ² ) w: Air volume (m ² / H _r ) Q _m : Average heating capacity (Kcal / H _r ) t _d : Defrost operation time (H _r ) In the above equation (a), C _p , r, w is almost constant, so Q _m is (ΔT , t _h , t _d ).

By the way, when the heating operation and the defrosting operation are alternately repeated, the heating capacity, that is, the use side coil (10)
The value is proportional to the temperature difference (ΔT), which is the difference between the air outlet temperature (T _o ) and the air inlet temperature (T _i ) during heating, but the state that changes with the passage of time is shown in Fig. 5. As shown, the transition of the temperature difference (ΔT) is zero at the start of heating operation (T _o ), and the difference increases with the operation and reaches the maximum temperature difference value (ΔT _M ). Then, since the capacity decreases as the frost adheres to and grows on the heat source side coil (8), the temperature difference (ΔT) gradually decreases and becomes close to saturation.

Therefore, from the temperature difference (ΔT) read every predetermined time, for example, every 30 seconds or 1 minute from the start of the heating operation, the integrated value (S) up to the present point of time starting from the start of the operation, that is, the heating capacity After the heating capacity value (S), which is the integrated value obtained by integrating the equivalent values, is sequentially calculated and the result shown in the diagram in FIG. 6 is obtained as the first stage, the heating capacity value (S )
The average heating capacity (Q _m ) is calculated by dividing the operating time (t _d ) of the defrosting operation performed immediately before the start of heating operation by the sum of the heating operation time (t _i ) after that. The result shown in the diagram of FIG. 7 is obtained as the second stage.

By the way, as is clear from the above-mentioned diagrams, the state of change of the heating capacity value (S) from the start of heating operation to the maximum temperature difference (ΔT _m ), that is, the maximum heating capacity value reaches a steep curve at a low level. And, after reaching the maximum heating capacity value, the capacity decline period is a high level and becomes a gentle curve,
Then, where the heating capacity value is low and saturated due to frost formation, the curve becomes abrupt at a high level.

Therefore, as shown in FIG. 7, the average heating capacity (Q _m ) is maximized immediately before the time when defrosting is required and the defrosting operation is required, and then decreases.

As is clear from the above points, if the defrosting is performed by determining the time when the average heating capacity (Q _m ) calculated in a certain period of time is the maximum, the EER is kept at the maximum and the heating operation and the defrosting operation are performed. Therefore, in order to find the condition that maximizes the value when calculating the periodic average heating capacity (Q _m ), the calculated value of this time is smaller than the calculated value of the previous time. It means that you can judge that.

In addition, the above description indicates that the temperature (Δ
It is premised that the transition of (T _n ) is performed slowly, but in recent air conditioners, the air volume of the use side coil is automatically or manually adjusted or compressed depending on the load state of heating operation. In many cases, the capacity of the machine is automatically adjusted. Therefore, it is necessary to control the defrosting operation in consideration of the fact that the fluctuation range of the temperature difference (ΔT _n ) becomes large during operation.

In this case, the actual heating capacity does not change so much when only the air volume is switched, but the actual heating capacity changes when the capacity of the compressor is controlled, but by performing the correction , And can be applied as the degree of ability deterioration before correction.

Therefore, the control mode in the case of switching the air volume will be described with reference to FIG. 8. For example, the temperature difference (ΔT) becomes smaller during the heating operation, and the air volume becomes the first air volume (W _H ).
Air volume decreases from the case of the switched on (W _L), the temperature difference when the temperature difference in the case of Teikazeryou (W _L) (ΔT _L) persisted large airflow (W _H) (ΔT _H Of course, it will be bigger than

On the other hand, even if the air volume is changed, the heating capacity of the air conditioner does not change much to the left and there is no problem assuming that they are substantially equal. Therefore, Q _H = Q _L (B) where Q _H : Air volume (W _H ) Heating capacity Q _L : heating capacity at air volume (W _L ). On the other hand, Q _H = Δt _H · C _P · r · W _H … (C) Q _L = Δt _{Since L} · C _P · r · W _L (D), from (B) to (D), Substituting equation (e) into equation (d), Becomes

From the above equation (f), the correction coefficient that is the temperature difference change ratio with respect to the temperature difference (ΔT _L ) after switching the air volume Even after switching the air volume by multiplying the, as a decrease degree of switching previous temperature difference ([Delta] T _H), it is possible to apply, therefore the temperature difference calculated this time ([Delta] T _n) and the temperature difference calculated last time ([Delta] T _{n −1} ) is considerably large, it is determined that the air volume switching has been performed, and the temperature difference change ratio (a)
Is calculated and the value obtained by multiplying the temperature difference after switching (ΔT _n ) by this is used, even if the temperature difference fluctuation due to the air volume switching occurs during the heating operation, there is no problem.

Note that there are two types of changes in the temperature difference (ΔT _n ) that increase or decrease the temperature difference. Therefore, the temperature difference calculated this time (ΔT _n ) and the temperature difference calculated last time (ΔT _n-1 ). The absolute value of the difference may be determined, and it may be determined whether or not this is larger than a predetermined value, for example, 2 ° C.

A flowchart for performing the defrosting operation based on the determination process described above will be described with reference to FIG.

The heating operation switch is turned on to start heating the air conditioner (step), and at the same time, initial setting is performed (step).

This initial setting is to reset the electronic timer to zero which is the starting point, set the heating capacity value (S) and the average heating capacity (Q) to zero, respectively, and at the start of operation, defrost operation is performed even once. Since it does not exist, it means that an appropriate defrosting time (t _d ) such as 5 minutes is set as one of the conditions for taking the subsequent timing, and these are stored in the microcomputer (17). .

Thus, the electronic timer starts measuring the time (step), reads the air outlet temperature (T _o ) and the air inlet temperature (T _i ) every time a certain time (eg, 1 minute) elapses (step), and reads the temperature difference (ΔT ) Is calculated and stored, and the elapsed time (t _i ) from the start of heating operation is measured and stored (step).

Within 3 minutes from the start of operation, the operation called hot start is performed, and it is a transitional period in which the refrigeration circuit is operated in the heating cycle with the use side fan (15) stopped. At the same time, the heating capacity value (S) is calculated and stored, and the average heating capacity (Q) is calculated from the heating capacity value (S), the defrosting time (t _d ) and the heating operation time (t _i ). Make a memory (step).

The calculation of the temperature difference (ΔT) in the step corresponds to the function of the temperature difference calculating means (1), and the calculation of the heating capacity value (S) and the average heating capacity (Q) in the step is the temperature difference integrating means ( 3) and the function of the average heating capacity calculation means (4).

When it is judged that the hot start operation has ended after 3 minutes and the normal warm air blowing operation has been reached (step), the process moves to the step and the measured and calculated temperature difference (ΔT _n ) and the previous measurement and Calculated temperature difference (Δ
T _n-1 ) and check if the absolute value of the difference is greater than 2 ° C. And, if it is less than 2 ° C, go to the step after step ′ that sets the correction coefficient (a) to 1 Meanwhile, 2 ℃
If it is determined that the difference is larger, the process proceeds to the next step, the correction coefficient (a) is calculated according to the above-described procedure, and the temperature difference (ΔT) is corrected in the step.

In this case, the step, ′, and the correction of the temperature difference (ΔT) in the step correspond to the function of the temperature difference correction means (2).

Thus, every 1 minute of running time steps,
, ′, Are repeatedly calculated and stored, but since the operation mode is unstable for some predetermined time, for example, about 20 minutes from the start of operation (there are uncertain factors), a guard timer that is one function of the electronic timer By the action (step), the average heating capacity value (memory) value (Q _n-1 ) of the previous calculation result is replaced with the average heating capacity value (Q _n ) of this calculation result (step) .

It should be noted that this step (12) is performed for 20 minutes from the start of operation in order to avoid erroneous judgment by ignoring the influence of the uncertain factors as described above in the comparison processing periodically performed by the comparison means (5). In order to play two roles, that is, to substantially invalidate the comparison operation and to input the previous operation result as the comparison value for the operation result of this time to the comparison means (5). It is a thing.

In this way, when 20 minutes have passed from the start of the heating capacity through the steps and the operation of the air conditioner is stabilized in a steady state, the average heating capacity value (Q _n ) calculated this time by the comparison means (5) and that of the previous heating ( Q _n-1 ) and make a size comparison (step).

If this comparison result is Q _n ≧ Q _n-1 , the step is moved to the same as described above, while if Q _n <Q _n-1 , the average heating capacity value is the maximum value at that time. This means that the defrosting signal is output from the comparison means (5) because it means that the state is in the state of shifting to the decrease after passing.

In this state, the deicer (16) further issues a signal for defrosting because the coil temperature of the heat source side coil (8) is frosted at -5 ° C or lower (step).
As a result, the defrosting command is transmitted from the microcomputer (17) and the time for the defrosting operation is also measured (step).

Thus, the frost is melted by entering the defrosting operation by the cooling cycle, but the mode of this defrosting operation is the defrosting command means, and the empty defrost operation which is unnecessary by providing this command means To be prevented.

In addition, when it is checked that two hours have passed from the start of the heating operation, and further that the frost detection signal is issued from the deicer (16), Q _n <Q _n- in the microcomputer (17). _{Even if} the calculation result of ₁ is not obtained, a means for forcibly entering the defrosting operation may be added.

After that, when a signal is issued from the deicer (16) due to the end of defrost, the defrost operation is ended and the heating operation is switched to (step).

In the step operation, the time (t _d ) required for the completed defrosting operation and the initial values (both are zero) for the heating capacity value (S) and the average heating capacity (Q) are set to the microcomputer (17). ) Is stored and the electronic timer is reset, and one cycle consisting of the heating operation and the defrosting operation is completed by the above, and the operation from step is performed again.

By the way, when checking the temperature change, there is a problem of lacking accuracy when catching the temperature change in the transitional period, so the sampling time until the temperature influence due to the change in air volume and the change in compressor capacity stabilizes, for example, every 1 minute. The predetermined time may be determined in advance based on the experimental data, such as every 2 minutes or every 3 minutes.

On the other hand, the comparison of the temperature difference (ΔT _n ) was performed based on the absolute value of 2 ° C. For example, in the case of air volume switching, the inlet temperature is about 18 ° C in a general heat pump air conditioner. For example, when switching from 100% to 80%, there is a temperature difference of 2 ° C or more, which is sufficient.

Further, even in the case of the compression function force control method by inverter control, for example, 30Hz, 40Hz,
Since most of them control the capacity stepwise, such as 50Hz, considering the case of switching from 70Hz to 60Hz, the capacity ratio changes by about 14%, which is 3 for the temperature difference (ΔT _n ).
Since it appears as a change of about 0 ° C, 2 ° C can be sufficiently dealt with as a reference.

The example explained above is for the case of an air-cooled air-conditioning system that is generally called an air-cooled air conditioner, and it is considered that there is no negative factor for the heating capacity by stopping the indoor fan during defrost operation. On the other hand, in the case of an air heat source / water utilization method called an air-cooled chiller, it is necessary to consider the negative capacity with respect to the heating capacity by cooling the hot water during the defrost operation, In that case, it is assumed that the temperature of the hot water drops by about 5 ° C.
The heating capacity commensurate with this temperature decrease may be subtracted, and otherwise the same calculation as in the above example may be performed.

(Effects of the Invention) As described above, the present invention finds a state in which the average heating capacity becomes the maximum value by calculation with respect to the phenomenon of a decrease in heating capacity due to frost formation, and performs defrosting operation according to this state. If a large change occurs in the temperature difference (ΔT _n ) of the fluid to be heated during heating operation due to switching of the flow rate of the fluid to be heated during the switching control, the temperature difference at that time is changed. Since it is corrected to a value equivalent to the previous operating state, it is possible to take proper defrosting timing and perform high-efficiency heating operation without any disturbance. There is an advantage that it can be applied to an air conditioner equipped with a variable capacity compressor.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a device circuit diagram according to an embodiment of the present invention, FIG. 3 is the same electronic control circuit diagram for defrost control, and FIG. 4 is a defrost control mode. FIG. 5 to FIG. 8 are explanatory diagrams showing changes in the heating capacity, the heating capacity integral value, the average heating capacity, and the temperature difference of the fluid to be heated with respect to the operating time. (1) ... Temperature difference calculation means, (2) ... Temperature difference correction means, (3) ... Temperature difference integration means, (4) ... Average heating capacity calculation means, (5) ... Comparison means, (10) ... Use side coil.

Front page continued (72) Inventor Takeo Ueno 1304 Kanaoka-cho, Sakai City, Osaka Prefecture Daikin Industries, Ltd. Sakai Plant Kanaoka Factory (72) Masami Horiuchi 1304, Kanaoka-cho, Sakai City, Osaka Prefecture Daikin Industries Kanaoka Co., Ltd. in the factory

Claims (1)

[Claims] 1. A temperature difference (ΔT _n ) is calculated periodically at regular intervals from the outlet temperature (T _o ) and inlet temperature (T _i ) of the fluid to be heated in the utilization side coil (10) during heating operation. The temperature difference calculating means (1) for storing this is compared with the previous temperature difference (ΔT _n-1 ) every time the temperature difference calculating means (1) calculates the temperature difference (ΔT _n ). , If the absolute value of the difference is larger than a predetermined value, the ratio between the previous temperature difference (ΔT _n-1 ) and the current temperature difference (ΔT _n ) is calculated as the correction coefficient (a), and the temperature difference is calculated. Calculation means (1)
The temperature difference correction in which each temperature difference (ΔT _n ) calculated after this time is multiplied by the correction coefficient (a) to correct to the equivalent temperature difference (ΔT ′ _n ) with respect to the operating state before the previous temperature difference calculation. From the temperature difference values calculated by the means (2) and the temperature difference calculation means (1) and corrected by the temperature difference correction means (2), the heating operation start time immediately after defrosting is used as a base point. Temperature difference integrated value (S)
The temperature difference integrating means (3) for calculating and storing the temperature difference and the temperature difference integrating value (S) calculated by the temperature difference integrating means (3) are used for the operation time (td of the defrosting operation performed immediately before the heating operation. ) And the subsequent heating operation time (ti), the average heating capacity calculation means (4) for calculating and storing the average heating capacity (Q _m ); and the average heating capacity calculation means (4). ) Comparing the current value and the previous value in the average heating capacity (Q _m ) calculated by), and outputting a defrost signal when the current value is small (5)
A defroster for an air conditioner, comprising: