JPH063312B2 - Defroster for air conditioner - Google Patents

Description

The present invention relates to a defrosting device for an air conditioner such as an air heat source heat pump machine.

(Prior Art) In the conventional defrosting device, a predetermined time, for example, 60 minutes has elapsed regardless of the capacity decrease rate, and the coil fin temperature from the defrosting command device is, for example, -5 ° C or less. By sending the defrost command signal,
The defrosting was started, but in this case, since the defrosting was performed irrespective of the reduction rate of the heating capacity, the efficiency decrease is often large and the heating efficiency is poor. EER) was low.

In order to improve such a point, a technique of detecting that the heating capacity has fallen to a certain extent and entering the defrost operation is proposed, and disclosed in Japanese Utility Model Laid-Open No. 57-16734.

This device calculates the heating capacity coefficient from the air temperature difference between the discharge air temperature and the suction air temperature of the use side coil and the air flow velocity, and stores the value of the heating capacity coefficient due to the accumulation of frost on the heat source side coil. It is designed to start defrosting when it falls to a set ratio with respect to the maximum heating capacity coefficient that has been set, and by detecting the start of defrosting as a state of decreased heating capacity, the defrosting start is left over. It is characterized by trying to get it done at an appropriate time, not too early or too late.

(Problems to be Solved by the Invention) It can be said that the device described above is appropriate in that the necessity of starting defrost is grasped as a decrease in heating capacity, but it is detected as a point when the heating capacity has fallen to a certain level. Therefore, unless this drop rate is chosen to be an appropriate value, it will result in either too early or too late, and it is actually difficult to find the condition of the drop rate necessary to keep the EER at the highest state. This is a difficult problem, and due to abnormal phenomena such as snowfall, it may malfunction due to changes in wind speed even though it has not frosted to the left.In particular, the progress of heating operation up to the start of defrost Since it is a control that has nothing to do with it, it is easy to actually try to perform defrost appropriately while keeping the EER determined by the balance between heating capacity and defrost operation high. It couldn't be revealed.

The present invention has been made in response to such a problem, and the present invention is different from the conventional point control system in which the necessity of the defrost operation is determined by the current event that actually occurred. The change in heating capacity is predicted while calculating the integrated value of heating capacity based on the progress of heating operation, and after considering the state of the defrost operation that was performed immediately before, it is appropriate for the actual heating operation. The purpose is to provide a continuous control system that attempts to perform defrost at the timing, and to improve the operating economy by maintaining the maximum ER value as well as optimizing the start of defrost operation. .

(Means for Solving Problems) Therefore, according to the present invention, as shown in FIG. 1, a defroster for an air conditioner includes a temperature difference detection means (1), a storage means (2), and a calculation means (3). ) And the defrost command means (4) .First, the temperature difference detection means (1) is configured so that the temperature difference detection means (1) is the outlet temperature (T _o ) And the inlet temperature (T _i ) are detected periodically for a predetermined time,
It has a configuration for outputting a temperature difference (ΔT _n ).

On the other hand, the storage means (2) is the defrost time (t _d ) of the defrost operation performed immediately before the heating operation, the temperature difference detection means (T _d ) that increases from the start of the heating operation and decreases after reaching the maximum value ( Each temperature difference value (ΔT _n ) output by 1) and the capacity increasing region operating time (t _f ) from the start of heating operation to the time point of outputting the maximum temperature difference value (ΔT _m ) are stored.

Next, the calculating means (3) calculates the capacity increasing area heating capacity (S _o ) corresponding to the product of the capacity increasing area operating time (t _f ) and the average value of each temperature difference value (ΔT _n ) within the time. The maximum temperature difference value (ΔT
Each temperature difference value then sequentially stored in the _m) from a combination of two values of ([Delta] T _n), the temperature difference values for between the time (T _x) (Δ
T) linear function (ΔT = a _i t _x + b _i ) is sequentially obtained, and the average proportionality coefficient (a _m ) and average constant (b _m ) obtained by averaging them
Is calculated (ΔT = a _m t _x + b _m ), the heating capacity (S) in the reduced capacity area is estimated from the integral of this average linear function, and the sum (S) _o + S) for heating operation time
(t _f + T _x ) and the previous defrost time (t _d ), the average capacity (Q _m ) is calculated as the maximum time, and this time and the capacity increasing area operating time (t _f ) Is output as the optimum defrost start time (t _u ).

Further, the defrost command means (4) is defrosted by the condition that the optimum defrost start time (t _u ) has passed after the heating operation is started and the signal for defrosting is issued from the detector for detecting frost formation. The defrost command is released under the condition that the defrost end is issued from the detector that issues the command and detects the defrost end.

(Operation) In the present invention, the average (heating) capacity (Q _m ) at the time when the immediately preceding defrost operation time (t _d ) and the subsequent heating operation time (t _f + T _x ) are added by the calculation means (3). there was calculated time indicating the maximum value (t _u) periodically, by predicting the optimum defrost time (t _u), since so as to perform the defrosting when defrost was necessary at that time , It is possible to make defrosting effective while always maintaining the heating integration capacity to the maximum.

Therefore, even when the outside air temperature is low and it is dry, it is not allowed to enter the defrost while the heating capacity has a margin until the integrated value of the heating capacity becomes maximum, so that empty defrost occurs before it occurs. It can be prevented.

(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 (5), a four-way switching valve (6), and a heat source side coil.
(7), the capillary tube (8), the use side coil (9) and the accumulator (10) constitute a known refrigeration circuit, and the refrigerant is circulated and used in the direction of the solid line during heating operation. The side coil (9) acts on the condenser, and the heat source side coil (7) acts on the evaporator, respectively.On the other hand, during cooling operation and defrost (defrost) operation, the refrigerant is circulated in the direction of the broken line arrow, The heat source side coil (7) acts on the condenser and the utilization side coil (9) acts on the evaporator, respectively. Needless to say, the flow direction of the refrigerant is switched by switching the four-way switching valve (6). In the case of the defrost operation, both the heat source side fan (13) and the use side fan (14) are stopped.

In FIG. 2, (11) is a first temperature detector that detects the air temperature at the outlet of the utilization side coil (9), and (12) is a second temperature detector that also detects the air temperature at the inlet. Both temperature detectors (11) and (12) are the temperature difference detecting means (1).
Constitutes the input element of.

On the other hand, (15) is a deicer that detects the coil inlet temperature of the heat source side coil (7) that functions as an evaporator during heating operation and is -2 ° C or lower, 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 or not, and is connected to the input end of the defrosting command means (4).

An electronic control circuit for controlling the defrosting of the air conditioner having the above-described configuration is as schematically shown in FIG. 3, and (16) is a well-known microcomputer, which includes a CPU (17), a RAM (18) and a ROM. It is composed of (19) as a basic element.

A program for controlling the CPU (17) is written in the ROM (19), and the CPU (17) fetches external data from the input port (20) or RAM according to the program.
(18) Performs arithmetic processing while exchanging data with the output port, and processes the processed data as necessary
Output to (21).

The output port (21) receives the output port designating signal from the CPU (17), temporarily stores the data in the port, and outputs an analog signal to the four way switching valve (6) via the D / A converter (25). It outputs to the solenoid (6 _S ) and the motor (14 _M ) of the user side fan (14).

On the other hand, when the input port (20) receives an input port designating signal from the CPU (17), it takes in necessary information to the port, and the air outlet temperature (in the heating side coil (9) during heating operation ( T _o ) is a digital signal via the A / D converter (22), and the air inlet temperature (T _i ) is a digital signal via the A / D converter (23). The coil inlet temperature of the coil (7) is output to the input port (20) as a digital signal through the A / D converter (24).

Therefore, the program control in the microcomputer (16) constitutes the temperature difference detection means (1), the storage means (2), the calculation means (3) and the defrost command means (4), and the ROM (19 4) and FIG. 5 are flowcharts showing the program written in).

Here, the theoretical basis for properly setting the timing of the defrost start time in the present invention will be described. This defrost start timing has a great influence on the integral capacity of heating, and the EER is improved. Must satisfy the condition that the heating integral capacity, that is, the integral value of the heating capacity from the end of the defrost operation to the end of the next defrost operation can be maximized,
The average heating capacity (Q _m ) when the user side fan (14) is stopped during defrosting in an air conditioner that uses an air heat source and air is given by the following formula.

However [Delta] T: mean temperature difference (℃) _{t h:} the heating operation time (H _r) c _p: air specific heat (kcal / kg · ℃) r : specific weight (kg / m ³⁾ w: air volume (m ³ / Hr) Q _m : Average capacity ((kcal / H _r ) t _d : Defrost operation time (H _r ) In the above equation (a), c _p , r, w are almost constant, so Q
_m can be regarded as a function of (ΔT, t _h , t _d ).

By the way, when the heating operation and the defrosting operation are alternately repeated, the state in which the heating capacity changes with the passage of time is as shown in FIG. 6. To obtain this capacity change curve, one heating operation is required. The seventh showing the capacity change curve in driving
In the figure, it is sufficient to analyze the carrying of the curve, and it is clear that the heating capacity is proportional to the temperature difference (ΔT _n ) which is the difference between the air outlet temperature (T _o ) and the air inlet temperature (T _i ). , It is possible to obtain the heating integral and the heating average capacity (Q _m ) by analyzing the transition of this temperature difference (ΔT _n ), obtaining it by an approximate expression, and performing integration processing.

However, the transition of the temperature difference (ΔT _m ) is zero at the start of heating operation (T _o ), and the difference increases with the operation, and when the maximum temperature difference value (ΔT _m ) is reached, the next frost The temperature difference (ΔT _n ) gradually decreases as the capacity decreases with the attachment / growth, and the state approaches saturation.

Therefore, first, in the region from the start of operation until reaching the maximum temperature difference value (ΔT _m ), that is, in the capacity increasing region, the average value of the temperature differences (ΔT _n ) read every predetermined time, for example, every one minute, is calculated. At the same time, the product of the average value and the operating time (t _f ) in the capacity increasing range is obtained, and a product of this and a constant can be calculated as the heating capacity (S _o ) in the capacity increasing range.

Next, from the time when the maximum temperature difference value (ΔT _m ) is reached, the area where the temperature difference decreases, that is, the capacity decrease area, is from the known part up to the present time when the temperature difference has already been read and the expected time to switch to the subsequent defrost. Since there is an unknown part, the ability must be calculated while predicting the unknown part. Therefore, the present invention provides a means for calculating the temperature difference transition that follows a curved line approximately as a straight line. It is adopted.
Therefore, from the combination of two values, the maximum temperature difference value (ΔT _m ) and each temperature difference value (ΔT _n ) read every minute thereafter, the temperature difference value for the time (t _x ) between them is calculated. The linear function of (ΔT) (ΔT = a _i t _x + b _i ) is sequentially processed by the microcomputer (16), and at the same time, each proportional coefficient (a _i ) and each constant (b _i ) and the average linear function (ΔT = a _m t _x + b _m ) having the average proportionality coefficient (a _m ) and the average constant (b _m ). Assuming that is the line that most closely approximates the temperature difference transition state until switching to defrost operation, the heating capacity (S) in the capacity reduction area may be obtained by integration based on this average linear function.

If we substitute a _m = a, b _m = b, t _x = x, If x ₂ −x ₁ = x _u and x ₁ = o, The average heating capacity (Q _m ), which is obtained from the cumulative heating capacity per one time from this equation (b) and the above equation (a), is Becomes

In addition, S _o = Q _o × x _f (d) where Q _o = average capacity in the capacity increasing range.

Needless to say, the defrost operation that makes the most effective use of the heating capacity can be performed by finding the condition that maximizes the equation (D) thus obtained and entering the defrost operation at this maximum point.

However, since the defrost operation time (x _d ) is unknown, it can be calculated by substituting the defrost operation time (t _d ) just before it is estimated that there will be no difference unless extreme fluctuation factors occur. Therefore, it is sufficient to obtain x _u where the value becomes 0 by differentiating the equation (c).

Note that x _u = x and x _d + x _f = c.

Since x is obtained when y ′ = 0, Therefore, the defrost timing time at the maximum integrative capacity is obtained from the equation (G).

However, since the time (x) in the equation (t) starts from the time when the maximum temperature difference value (ΔT _m ) is reached, the optimum defrost start time (t _u ) from the heating operation start time is Becomes

A flow chart for performing the defrosting operation by the above-described calculation processing will be described with reference to FIGS. 4 and 5, in which the heating operation switch is turned on to start heating the air conditioner (), and the initial setting is performed ( ).

Since the defrosting operation has never been performed with this initial set, the defrosting operation time is set as one of the conditions for timing after that.
Microcomputer (16) which sets appropriate time such as minutes
To memorize.

Simultaneously with the start of the heating operation, the air outlet temperature (T _o ) and the air inlet temperature (T _i ) are read, for example, every minute and the temperature difference (ΔT _n ) is stored ().

Then, when it is judged that this temperature difference (ΔT _n ) has reached the maximum value (), the maximum temperature difference (ΔT _m ), the capacity increasing region operating time (t
_f ) and the average value of the temperature difference value (ΔT _n ) are stored ().

After that, the calculation process for determining the defrost timing and the defrost command are performed (), which reads the both temperatures (T _o ) and (T _i ) at intervals of 1 minute, as shown in FIG. _(-1) continue the calculation of _{ΔT = a i t x + b} i performed _(-2), (a _m) and then to (b _m) calculation of _(-3), the average primary function calculation and integral and derivative The optimum defrost start time (t _u ) is calculated ( _-4 ) by the microcomputer (16) by a series of calculation of the above, and after 20 minutes of the set time ( _-5 ), the deicer (15) changes the coil temperature. The defrost command is sent from the microcomputer (16) because the frost formation due to the drop has been detected ( _-7 ) and the heating operation time has reached the optimum defrost start time (t _u ) ( _-8 ). Te _(-9), the defrosting operation by the cooling cycle Selle.

If it is checked that 2 hours have passed from the start of the heating operation ( _-6 ), and further that the defroster (15) has issued a frost detection signal ( _-10 ), the microcomputer (16) In the above, even if the calculation result of the optimum defrost start time (t _u ) is not obtained, it is forcibly switched to the defrost operation.

After that, when a signal is issued from the deicer (15) due to the end of the defrost, the defrost operation is ended and the heating operation is switched to ().

After this switching, the defrost time (t _d ) of the completed defrost operation is stored in the microcomputer (16) (), and the heating operation and the defrost operation are completed as described above.
The cycle is complete and the operation from step is performed again.

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.

The following is an experimental example when the defrosting operation is performed based on the above procedure. The heating operating condition is that the maximum temperature difference (ΔT _m ) =
20 ° C., previous defrost time (t _d ) = 1 to 10 minutes, capacity increasing region operating time (t _f ) = 5 minutes, average temperature difference value within the time
When (ΔT) = 14 ° C, the heating time (t _u ) until the defrost operation starts is plotted on the horizontal axis and the temperature difference after 1 hour
The diagram with (ΔT _n ) on the vertical axis is as shown in Fig. 8 with the defrosting operation (t _d ) as a parameter. Taking the case where the defrosting time is 5 minutes as an example, the capacity after 1 hour is , The optimum defrost start time (t _u ) is 60 minutes, while the capacity after 1 hour is It became 28 minutes at the time of, and the heating integral capacity became the maximum in all cases.

(Effects of the invention) As described above, the present invention controls the switching of the defrosting operation by calculating the time for which the cumulative result of the heating capacity becomes the maximum value for the capacity deterioration due to frost formation.
There is no longer the possibility of entering the defrost quickly even if there is room for heating capacity, or delaying the defrost even if the capacity is degraded, and it is possible to take the optimum defrost timing considering the surrounding conditions. Becomes possible,
Thus, proper defrosting is possible while maximizing the EER during heating operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a circuit diagram of an apparatus according to an embodiment of the present invention, FIG. 3 is an electronic control circuit diagram for defrosting control, and FIGS. A flowchart showing a defrosting control mode, FIGS. 6 and 7 are theoretical explanatory diagrams showing a change in heating capacity (temperature difference) with respect to an operating time, and FIG.
The figure is a defrost optimum time diagram according to an embodiment of the present invention. (1) ... temperature difference detection means, (2) ... storage means, (3) ... calculation means, (4) ... defrost command means, (9) ... use side coil.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masami Horiuchi, 1304 Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industries, Ltd.Kanaoka Plant, Sakai Manufacturing Co., Ltd. (72) Hideki Tsujii, 1304, Kanaoka-machi, Sakai City, Osaka Daikin Industries, Ltd. Sakai Plant Kanaoka Factory

Claims (1)

[Claims] 1. An outlet temperature (T _o ) and an inlet temperature (T _i ) of a fluid to be heated in a utilization side coil (9) during heating operation are periodically detected for a predetermined time to determine a temperature difference (ΔT _n ). Outputting temperature difference detection means (1), defrost time (t _d ) of defrost operation performed immediately before heating operation, detection of the temperature difference that tends to increase from the start of heating operation and reach the maximum value and then decrease Storage means (2) that stores the temperature difference value (ΔT _n ) output by the means (1) and the capacity increase region operating time (t _f ) from the start of heating operation to the time of outputting the maximum temperature difference value (ΔT _m ). ) And the operating time (t _f ) in the capacity increasing range and the temperature difference values (ΔT
_n ) the heating capacity (S _o ) in the capacity increasing area corresponding to the product of the average value and the maximum temperature difference value (ΔT _m ) and the temperature difference values (ΔT _n ) which are sequentially stored. From the combination of values, the linear function of the temperature difference value (ΔT) with respect to the time (T _x ) between them (ΔT = a _i t _x + b
_i ) is obtained sequentially, and the average linear function (ΔT = a) having the average proportionality coefficient (a _m ) and the average constant (b _m ) obtained by averaging them is calculated.
_m t _x + b _m ), the heating capacity (S) is estimated from the integral of this average linear function, and the sum (S _o + S) of both heating capacities is calculated as the heating operation time (S _o + S). t _f + T _x ) and the previous defrost time (t _d ) divided by the sum of the average capacity (Q _m ) is calculated as the maximum time, and this time and the capacity increasing area operating time (t _f ) And a calculating means (3) for outputting the sum of the optimum defrost start time (t _u ) and the detector for detecting frost after the optimum defrost start time (t _u ) has elapsed after the start of heating operation. A defrost command is issued under the condition that a signal requiring defrost is issued, and a defrost command means (4) for canceling the defrost command under the condition that the defrost end is issued from the detector that detects the end of defrost is provided. Defroster for air conditioners.