JPH08121917A - Refrigerant quantity determining device - Google Patents

Abstract

PURPOSE: To compute the percentage of refrigerant quantities based on the relation of a proper opening of an expansion valve to the opening of the expansion valve at a present time, and display the determination of the sealed refrigerant quantity. CONSTITUTION: A relation table 47 stores preliminarily information about a total rotary speed of a compressor during operation with a proper amount of refrigerant sealed in a heating cycle, a refrigerant vaporization temperature of an outdoor heat exchanger, and a total proper opening of an outdoor expansion valve. The proper opening of the expansion valve at that point of time is determined by reference to the relation table 47 by way of a reference mechanism 49 of the relation table. The rotary speed of the compressor and a detected temperature value of a vaporizer, which are indexes in the relation table 47, are input thereby determining the proper opening of each expansion valve at that point of time on reference to the relation table 47 based on the input values. Then, the ratio S of the proper opening of the expansion valve to the opening at that point of time is represented by a formula I S = opening/proper amount of opening, and the ratio S1 of the proper amount of refrigerant to the amount of refrigerants at that point of time is computed based on a formula II S1 =2-S, to display as a numerical value the determination results S1 of the amount of refrigerant on a display 42 by every specified time by a refrigerant quantity arithmetic operation mechanism 51.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant amount determination device for determining and displaying the amount of refrigerant enclosed in a cooling / heating cycle of a multi-room air conditioner based on an appropriate amount of refrigerant.

[0002]

2. Description of the Related Art Conventionally, there are the following two types of devices for determining and displaying the amount of refrigerant enclosed in the refrigeration cycle of an air conditioner.

(1) Hard method This method is a method for estimating the refrigerant amount in a cycle by directly detecting the refrigerant amount in a container such as an accumulator or receiver in a refrigeration cycle with a unique detector.

Known examples of these are JP-A-58-6677.
4, JP-A 63-25462, JP-A 1-107071, JP-A
3-199873 gazette etc. are mentioned.

Since these methods require a detector such as a temperature sensor or an ultrasonic sensor, they cannot be used as general methods, and there is a problem that the cost is high.

(2) Soft method This method uses cycle state quantities such as temperature and pressure,
This is a method of indirectly estimating the amount of refrigerant in the cycle based on the manipulated variables such as the rotation speed of the compressor and the opening degree of the expansion valve.

Known examples of these are disclosed in Japanese Patent Application Laid-Open No. 63-1613.
75, JP2-208469, JP3-286980, JP
6-74621 publication and the like.

In these systems, by using the temperature and pressure detected by the same detector as used in the conventional cycle control, (1) it is necessary to use a unique detector such as the hardware method. Since it does not exist, there is a feature that it does not cost.

[0009]

In the above-mentioned conventional soft method, since a unique detector for judging the amount of refrigerant is not used, the accuracy of judging the amount of refrigerant is not good. There is a problem that you can only do it.
For this reason, it is difficult to quantitatively display the amount of the refrigerant as in the hardware method, and the operator can only roughly recognize the excess or deficiency of the refrigerant. Therefore, if the detection of the excess or deficiency of the amount of refrigerant is delayed, there is a possibility that a malfunction will occur, which is not preferable in terms of the reliability of the air conditioner. However, if the sensitivity for detecting the excess or deficiency of the refrigerant amount is set to be too high, there is a risk of adding or releasing an unnecessary amount of refrigerant, which is also inconvenient because of the labor and waste of the refrigerant.

It is an object of the present invention to provide a refrigerant amount determination device which is based on the principle of the conventional soft method but has a determination accuracy comparable to that of the hardware method capable of quantitatively determining and displaying the refrigerant amount as compared with the conventional method. is there.

[0011]

In order to achieve the above object, the present invention comprises one outdoor unit and a plurality of indoor units, and the outdoor unit has a variable capacity in which the number of rotations is variable. A compressor, an outdoor heat exchanger, an outdoor expansion valve, and an outdoor fan whose rotation speed is variable. Each indoor unit has an indoor heat exchanger, an indoor expansion valve, and an indoor room whose rotation speed is variable. In a multi-room air conditioner that is equipped with a fan and sequentially connects them to form a cooling / heating cycle, the total number of revolutions of the compressor and the outdoor heat exchanger when operating with a proper amount of refrigerant during heating. The relationship data between the wet-bulb temperature of the intake air or the evaporation temperature of the refrigerant and the total appropriate opening of the outdoor expansion valve is stored in advance, and the total number of rotations of the compressor at that time and the intake air of the outdoor heat exchanger are stored. Of the outdoor expansion valve and the wet-bulb temperature of the Based proper opening of the relationship between the total degree of opening of the outdoor expansion valve of that time, also during the cooling, the
The total rotational speed of the compressor and the average wet-bulb temperature of the intake air of the indoor heat exchanger or the average temperature of the blown-out air and the total appropriate opening degree of the indoor expansion valve when operating with the appropriate amount of refrigerant enclosed. The relevant rotational speed of the compressor and the average wet-bulb temperature of the intake air of the indoor heat exchanger or the average temperature of the blow-out air of the compressor and the total opening of the indoor expansion valve are properly stored. Degree and the total opening degree of the indoor expansion valve at that time, the ratio of the amount of refrigerant to the proper amount of refrigerant or the appropriateness or inadequacy of the amount of refrigerant to the proper amount of refrigerant is determined at predetermined time intervals during a predetermined time. A device for making a judgment display is provided.

[0012]

In the refrigerant quantity determination device of the present invention, taking the heating time as an example, the total number of revolutions of the compressor and the wet air of the intake air of the outdoor heat exchanger when operating with the proper amount of refrigerant enclosed. The relational data of the temperature or the evaporation temperature of the refrigerant and the total appropriate opening of the outdoor expansion valve is stored in the device in advance, and with reference to this, the total number of rotations of the compressor at that time and the outdoor heat exchanger Determine the total appropriate opening of the outdoor expansion valve and the wet bulb temperature of the intake air or the evaporation temperature of the refrigerant. Then, the refrigerant amount is determined and displayed based on the relationship between the proper opening amount and the actual total opening amount of the outdoor expansion valves at that time. Therefore, a unique detector for determining the amount of refrigerant is not required, and no extra cost is required.

The value of the ratio between the appropriate opening and the opening at that time, or the value obtained by subtracting the ratio of the opening at that time and the appropriate opening from 2 or these values, the capacity of the container such as the accumulator or receiver. The ratio of the refrigerant amount at that point in time to the proper refrigerant amount is a value obtained by applying a non-linear function correction such as the characteristics and the expansion valve opening flow rate characteristic, and this ratio calculated for each predetermined time interval or the average value of this ratio for a predetermined number of times Is numerically displayed, or based on this, whether the refrigerant amount is appropriate or not suitable for the appropriate refrigerant amount is divided into a plurality of stages and displayed as symbols, and these results are stored and read out.
Therefore, it is possible to quantitatively determine whether the amount of refrigerant is excessive or insufficient with respect to the appropriate amount of refrigerant. Therefore, the operator can accurately check the quality of the sealed refrigerant in the air conditioner. As a result, it is convenient in terms of reliability of the compressor and the like, and also in terms of user comfort.

In addition, after a lapse of a predetermined time after the start of operation, in a case where the operation state applies to the relational data stored in advance, the cycle state quantity of temperature and pressure, the rotation speed of the compressor and the opening degree of the expansion valve are Only when the operation amount is stable within the predetermined range for the predetermined time and there is no defrosting operation or ON / OFF operation of the indoor unit and normal operation is continued, the proper or inadequate amount of refrigerant is determined. The judgment is displayed, and when it is impossible to judge whether the amount of refrigerant is proper or not, the content thereof is displayed.
Therefore, the accuracy of the determination of the amount of the refrigerant is high and stable, and the work of additionally charging or discharging the refrigerant can be efficiently performed based on the result of the determination.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view of a multi-room air conditioner in which a plurality of indoor units are connected to one outdoor unit. Reference numeral 1 is an outdoor unit that is installed outdoors. As a basic component, a variable capacity compressor with variable rotation speed, an outdoor heat exchanger 3, and a variable rotation speed are provided. An outdoor fan 4, an accumulator 5, a four-way valve 6, a receiver 7 and an outdoor expansion valve 8 for controlling the flow rate of the refrigerant flowing into the outdoor heat exchanger 3 are provided. A plurality of indoor units 9a, 9b, 9c are connected to the outdoor unit 1 in parallel. In this figure, the case of three rooms is described, but the present invention is not limited to this number. Each indoor unit includes an indoor heat exchanger 10a, 10b, 10c, an indoor fan 11a, 11b, 11c with a variable rotation speed, and an indoor heat exchanger 10a, 1c.
Indoor expansion valve 12 for controlling the flow rate of the refrigerant of 0b, 10c
a, 12b, 12c are provided. The outdoor unit 1 and the indoor units 9a, 9b, 9c are connected by a gas pipe 13, its branch pipe 14, its branch pipes 14a, 14b, 14c, a liquid pipe 15, its branch pipe 16 and its branch pipes 16a, 16b, 16c. Has been done. By these, the heating and cooling cycle of each room is configured.

The flow of the refrigerant when heating each room is as shown by the solid line. At this time, the four-way valve 6 is in the state shown by the solid line in FIG. The high-temperature high-pressure gas refrigerant discharged from the compressor 2 is sent to the operating indoor units 9a, 9b, 9c via the gas pipe 13. In each indoor unit, the indoor heat exchangers 10a, 10
At b and 10c, the gas refrigerant condenses and heats the inside of the room to become a liquid refrigerant. Then, via the liquid pipe 15, the receiver 7 of the outdoor unit 1
Return to Then, the liquid refrigerant that has exited the receiver 7 is evaporated by the outside air in the outdoor expansion valve 8 and the outdoor heat exchanger 3 to become a low-temperature low-pressure gas refrigerant, and returns to the compressor 2 via the four-way valve 6 and the accumulator 5.

On the other hand, when cooling each chamber, on the contrary, the flow of the refrigerant is as shown by the broken line. The four-way valve 6 is in the state shown by the broken line in FIG. The high-temperature and high-pressure gas refrigerant discharged from the compressor 2 is condensed by the outside air in the outdoor heat exchanger 3 to become a liquid refrigerant. After that, through the receiver 7 and the liquid pipe 15,
It is sent to the indoor units 9a, 9b, 9c in operation. In each indoor unit, the liquid refrigerant evaporates in the indoor expansion valves 12a, 12b, 12c and the indoor heat exchangers 10a, 10b, 10c to cool the room and become a low-temperature low-pressure gas refrigerant. Then, it returns to the compressor 2 through the gas pipe 13 and the accumulator 5 of the outdoor unit 1. At this time, the bypass passage 17 and the bypass expansion valve 18 may bypass the liquid refrigerant to the suction side of the accumulator 5 to adjust the operating state of the compressor 2.

In the cooling / heating cycle of the multi-room air conditioner as described above, the air conditioning capacity of each indoor unit is adapted to the air conditioning load according to the outside air condition while maintaining the compressor 2 in a safe and stable operating state. Therefore, it is required to provide the user with a comfortable air conditioning environment. Therefore, a control device 19 having a plurality of feedback control functions as shown in FIGS. 2 and 3 is attached.

FIG. 2 is a block diagram illustrating the function of the control device 19 during the heating cycle. Compressor 2
With respect to the above, it has a feedback control function of controlling the discharge pressure and the discharge temperature to respective target values. Explaining this function, first, the target value of the discharge pressure of the compressor 2 is given by the setting mechanism 21. Next, the deviation between this target value and the detection signal of the discharge pressure detector 22 provided on the discharge side of the compressor 2 is obtained, and the compressor 2 is reduced so as to reduce this deviation.
The control calculation mechanism 23 calculates the rotation speed of the rotation speed of 2. Based on this result, the inverter 24 controls the rotation speed of the compressor 2. Similarly, the target value of the discharge temperature of the compressor 2 is given by the setting mechanism 25. Next, this target value and the discharge temperature detector 26 provided on the discharge side of the compressor 2
The deviation from the detection signal is calculated, and the opening degree of the outdoor expansion valve 8 is calculated by the control calculation mechanism 27 so as to reduce the deviation. Based on this result, the flow rate of the refrigerant passing through the outdoor heat exchanger 3 is controlled, and thereby the discharge temperature of the compressor 2 is controlled.

On the other hand, the indoor units 9a, 9b, 9c have a feedback control function for controlling the room temperature to the set value regardless of the load fluctuation. To explain this function, first, the set value of the room temperature of each room is the room temperature setter 28.
a, 28b, 28c. Next, the deviation between this target value and the detection signals of the room temperature detectors 29, 29b, 29c provided on the suction sides of the indoor heat exchangers 10a, 10b, 10c is determined, and the indoor expansion valve 12a,
The control calculation mechanism 30 calculates the opening degree of 12c. Based on this result, the flow rate of the refrigerant passing through the indoor heat exchanger 10 is controlled, and thereby the heating capacity is controlled. In connection with this, a temperature detector 31 for blown air is additionally provided.

FIG. 3 is a block diagram illustrating the function of the control device 19 during the cooling cycle. Compressor 2
In contrast, it has a feedback control function for controlling the suction pressure and the discharge temperature to respective target values. Explaining this function, first, the target value of the suction pressure of the compressor 2 is given by the setting mechanism 32. Next, the deviation between this target value and the detection signal of the suction pressure detector 33 provided on the suction side of the compressor 2 is obtained, and the compressor 2 is reduced so as to reduce this deviation.
The control calculation mechanism 34 calculates the rotation speed of the. Based on this result, the inverter 24 controls the rotation speed of the compressor 2. Similarly, the target value of the discharge temperature of the compressor 2 is given by the setting mechanism 35. Next, the deviation between this target value and the detection signal of the discharge temperature detector 26 provided on the discharge side of the compressor 2 is obtained, and the opening degree of the indoor expansion valve 12 is calculated by the calculation mechanism 36 so as to reduce this deviation. . Based on this result, the flow rate of the refrigerant passing through the indoor heat exchanger 10 is controlled, and thereby the discharge temperature of the compressor 2 is controlled.

On the other hand, the indoor units 9a, 9b, 9c have a feedback control mechanism for controlling the room temperature to the set value irrespective of load fluctuations. To explain this function, first, the set value of the room temperature of each room is the room temperature setter 28.
a, 28b, 28c. Next, the difference between this target value and the detection signals of the room temperature detectors 29a, 29b, 29c provided on the suction side of the indoor heat exchangers 10a, 10b, 10c is determined, and the indoor expansion valve 12 is made to reduce the deviation.
It is calculated in the control calculation mechanism 37 of the opening degree of a, 12b, 12c. Based on this result, the flow rate of the refrigerant passing through the indoor heat exchanger 10 is controlled, thereby controlling the cooling capacity. In connection with this, an outside air temperature detector 38 is attached.

2 and 3, a refrigerant amount determination device 39 of the present invention is attached. This is composed of a refrigerant amount determination means 40, a switch 41 for manually controlling the same, and a display 42 for displaying the determination result.

The configuration of the multi-room air conditioner is not limited to this, and may be one having a heat storage / cooling tank, one having indoor units capable of cooling and heating simultaneously, or the like.

In this air conditioner, there is an appropriate amount of refrigerant in order to provide proper heating and cooling capacity with respect to the air conditioning load. This proper amount of refrigerant can be regulated based on the capacity of the outdoor unit, the combination of the capacity of the indoor unit and the number of units, the pipe thickness, the pipe length, and the like. Usually, in a multi-room air conditioner, a predetermined amount of refrigerant is pre-filled in the outdoor unit at the time of shipment. Then, at the installation site of the air conditioner, the calculation of the refrigerant amount is performed by the worker,
The required refrigerant is additionally enclosed. As a result, an appropriate amount of refrigerant can be secured. However, when the worker additionally fills the refrigerant, the proper amount of the refrigerant is not filled due to an error in the estimation of the pipe length, an error in measuring the weight of the added refrigerant amount, a mistake in operating various valves when filling the refrigerant, and the like. In some cases, there may be too few or too many. Even if an appropriate amount of the refrigerant is filled at this time, the refrigerant may leak from the joint portion of the pipe or the like for a long period of time and the amount of the refrigerant may become too small. When the proper amount of refrigerant is filled, the feedback control function of FIGS. 2 and 3 works as designed, and the cycle of FIG. 1 can be controlled to each target value by the manipulated variable as designed. This case is set as the reference state of the cycle with an appropriate amount of refrigerant. On the other hand, when there is an excess or deficiency in the refrigerant amount, even if the same feedback control function works, the reference state of this cycle is not reached. In other words, there is some correlation between the amount of refrigerant and the state of the cycle. The principle of the refrigerant amount determination device 39 of the present invention utilizes this phenomenon. In particular, it is a method of determining the refrigerant amount based on the relationship between the refrigerant amount and the opening degree of the outdoor or indoor expansion valve.
This principle will be described in detail below with reference to FIG.

FIG. 4 is a schematic diagram of a multi-room air conditioner showing the principle of the refrigerant amount determination in the refrigerant amount determination means 40. Since it is based on the same determination principle regardless of the heating cycle and the cooling cycle, it will be described with reference to FIG. 4 which is a simplified version of FIG. 2 is a compressor, 43 is a condenser, 7 is a receiver, 44 is an expansion valve, and 45 is an evaporator. By sequentially connecting these with piping, a heating cycle and a cooling cycle corresponding to FIG. 1 are obtained. The high-temperature and high-pressure gas refrigerant discharged from the compressor 2 absorbs heat in the condenser 43 to become a liquid refrigerant, which is temporarily stored in the receiver 7. After that, the expansion valve 44 and the evaporator 45 radiate heat to become a low-temperature low-pressure gas refrigerant, and return to the compressor 2. 2 and 3 for this cycle as well.
The feedback control function of is still active. Of these, the discharge temperature of the compressor 2 is controlled to a target value by controlling the opening degree of the expansion valve 44 and controlling the flow rate of the refrigerant passing through the expansion valve 44 and the evaporator 45. With an appropriate amount of refrigerant, the opening degree of the expansion valve 44 is in the reference state together with the cycle state. On the other hand, when the refrigerant has an excess or deficiency, the opening degree of the expansion valve 44 deviates from this reference state. At this time, the amount of refrigerant and the expansion valve 44
There is a strong correlation with the degree of opening. That is, on the contrary, the amount of the refrigerant can be accurately estimated from the opening degree of the expansion valve 44 based on the reference state. However, in order to strictly specify the state of the cycle, it is necessary to at least specify the states of the compressor 2 and the evaporator 45. Therefore, with respect to the opening degree of the expansion valve 44, the rotation speed of the compressor 2 and the evaporator 4
Associate 5 behavior levels. When there are a plurality of compressors 2, the total number of rotations is used. Here, the total number of rotations means that the correction coefficient of the discharge flow rate of the compressor is k _i ,
It is an amount represented by Σk _i · (rotation speed) _i . The operation level of the evaporator 45 is as follows: the dry-bulb temperature of the intake air, the wet-bulb temperature, the dry-bulb temperature and the wet-bulb temperature of the blown air as the air side conditions, and the inlet-side evaporation temperature and the outlet side as the refrigerant side conditions. Examples include evaporation temperature and superheat. If all these states are specified, the accuracy of the refrigerant amount determination will be improved, but the calculation will be complicated, so this is not a practical solution. On the other hand, the evaporator 4
Although the accuracy of determining the amount of refrigerant is good if it is defined only by the wet-bulb temperature of the blown air of No. 5, a unique detector for detecting the wet-bulb temperature is required. In the heating cycle, the alternative temperature is the inlet-side evaporation temperature of the refrigerant. In the cooling cycle, the dry-bulb temperature of blown air (simply called temperature) is used. Since these detectors are already installed for the feedback control function of FIGS. 2 and 3, there is an advantage that an extra detector is not required. When there are a plurality of evaporators 45, the total opening of all expansion valves 44 is used. Here, the total expansion valve opening is a sum for the indoor unit (evaporator) in operation, where the expansion valve flow rate correction coefficient is k _j , and Σk _j · (expansion valve opening) _j
Is the amount represented by. Further, the evaporation temperature on the inlet side of the refrigerant and the wet-bulb temperature of the blown air are also average values of a plurality of units. In addition, the discharge pressure and suction pressure of the compressor 2 and the operation level of the condenser 43 define the cycle state.
Further, the pipe length, the capacity characteristic of the receiver, the flow rate characteristic of the expansion valve, the wind speed of the fan 46 of the evaporator 45, etc. are also related to the state of the cycle. Since these do not have a major effect, they are used as a means for correcting the determination result as needed.

The configuration of the refrigerant amount determination device 39 embodying the principle of the refrigerant amount determination described in FIG. 4 will be described with reference to the block diagram of FIG. Of these, the refrigerant amount determination means 40
Is composed of the following mechanisms.

First, in the relation table 47, information regarding the opening of the expansion valve as shown in FIGS. 6 and 7 is stored in advance. FIG. 6A shows the total number of revolutions (f ₁ , f ₂ ...) Of the compressor and the evaporation temperature of the refrigerant in the outdoor heat exchanger when a proper amount of refrigerant is enclosed and operated in the heating cycle.
(t _e1 , t _e2 ……) and the total appropriate opening of the outdoor expansion valve
It is a graph showing the relational data of (V ₀ ). Using this graph based on the rotation speed F and the evaporation temperature T _e of the outdoor heat exchanger compressor, it is possible to obtain the proper degree V ₀ which outdoor expansion valve at that time. FIG. 6B is a graph in which this graph is replaced with a discrete table so that it can be stored easily. Again, the proper opening degree of the outdoor expansion valve can be obtained using the two values of the evaporation temperature of the outdoor heat exchanger and the rotation speed of the compressor as indexes. However, when the index is not in the table, the proper opening degree of the outdoor expansion valve may be obtained by linear interpolation calculation.

On the other hand, FIG. 7 (a) shows the total number of revolutions of the compressor ((f ₁ , f ₂ ...) And the indoor heat exchanger when operating with the proper amount of refrigerant enclosed in the cooling cycle. It is a graph showing the relational data of the average value (t _a1 , t _a2 ...) Of the temperature of the blown air and the total proper opening (V _i ) of the indoor expansion valves. The total proper opening degree V _i of the indoor expansion valve at that time can be obtained based on the average value T _a of the temperature of the blown air and the rotation speed F of the compressor. It is replaced with a discrete table for easier storage. Again, the total value of the indoor expansion valves is determined by the two values of the average value of the temperature of the air blown out from the indoor heat exchanger and the rotation speed of the compressor. It is possible to calculate the opening, but if the index is not in the table, use a linear interpolator. The maximum and minimum values of each index are limited by the design operating state of the cycle, so the capacity of the table is determined from this. Needless to say, it is necessary to set each index so that the required determination accuracy can be secured.

Since these relationship tables 47 differ depending on the capacity of the outdoor unit, all the relationship tables for each capacity of the outdoor unit are stored in advance. Control device 19
If the relation table selection mechanism 48 makes a selection based on the outdoor unit capacity information obtained from the above, the same refrigerant amount determination means 40 can be used regardless of the outdoor unit capacity.

It should be noted that these relationship tables 47 can be made highly reliable by sufficiently performing a test operation in which an appropriate amount of refrigerant is put in advance before the product is shipped. Further, at this time, the performance of the present refrigerant amount determination means 40 can be confirmed by performing a test operation with the refrigerant amount intentionally made excessive or insufficient, which is an effective method.

Next, the relation table reference mechanism 49 refers to the relation table 47 to obtain the appropriate opening degree of the expansion valve at that time. For this purpose, the rotational speed of the compressor and the detected value of the temperature of the evaporator, which are the indexes of the relationship table 47, are input, and based on this, the relationship shown in FIGS. The appropriate opening degree of each expansion valve at that time is obtained by referring to the table 47. Then, based on the relationship between the appropriate opening degree of the expansion valve and the actual opening degree of the expansion valve at that time, the actual refrigerant amount with respect to the appropriate refrigerant amount is determined. At this time, if the state of the cycle is not stable, the accuracy of determining the amount of refrigerant decreases. For example, immediately after the air conditioner is started, or when the outdoor unit is performing defrosting operation due to a change in the air conditioning load, if some of the indoor units repeatedly turn on and off, the cycle state , The state quantity of the cycle of temperature and pressure, the number of revolutions of the compressor, and the manipulated variable of the opening degree of the expansion valve are not fixed, and the calculation accuracy of the refrigerant amount determination described below cannot be ensured. Therefore,
The stability determination mechanism 50 determines whether or not the cycle state is stable based on these pieces of information, and then determines the refrigerant amount. Various methods can be considered for determining the stability of the cycle, but here, the method shown in the flowchart of FIG. 8 will be described. It is advisable to execute the operation of the refrigerant amount calculation described below including this stability determination operation at predetermined time intervals. This is not only convenient when the refrigerant amount determination means 40 is implemented by using a microcomputer or the like like the control device 19, but by using a plurality of information for each predetermined time interval, statistical processing can be performed. By using the method, it is possible to reduce variations in input data and improve the accuracy of refrigerant amount determination. The time interval of this operation, the number of points of information that is the basis of the statistical processing, and the like are determined based on the degree of data variation for stability determination and the required accuracy of refrigerant determination. Generally, the longer the time interval of the operation and the larger the number of information points, the higher the accuracy of determination can be expected. However, if the operation time interval is set too long, or if the number of information points is set too large, the accuracy of the mark will vary, or the probability of meeting the predetermined condition for determining the refrigerant amount will be low. It should be noted that the operation of determining the amount of refrigerant may not be completed forever.

First, (A) the current opening v ₅ of the expansion valve is input. Then, (B) the average value v based on the opening degrees v ₁ , v ₂ , v ₃ , v ₄ , and v ₅ of the expansion valve at five points up to the present time.
Is calculated. Next, (C) calculates the deviation between the opening degree v ₅ of this mean value and the current of the expansion valve, compared with the allowable variation range Δv of diverticula expansion valve opening degree as a reference for the deviation and stability determination. When this deviation is smaller than the allowable fluctuation width Δv, it means that the fluctuation of the cycle state is small. And (D)
If such a condition occurs continuously for 5 time points, it is assumed that the cycle state is stable at that time,
The operation of the refrigerant amount determination described below can be started. On the other hand, when this deviation is larger than the fluctuation width Δv, it means that the fluctuation of the cycle state is large. Even if this deviation is smaller than the permissible fluctuation range Δv, if this condition does not occur continuously for five time points, it means that the state of the cycle is still fluctuating and not stable. There is. In such a case, since the accuracy of the (F) refrigerant amount determination is poor, it is a good idea to wait until the cycle state stabilizes without performing the operation to ensure the predetermined determination accuracy. In such a case, displaying this content on the display 42 is convenient because the operator can confirm it.

Only when the above conditions are satisfied, the refrigerant amount calculation mechanism 51 can calculate the refrigerant amount. This calculation method is shown in FIG. The ratio of the proper opening degree of the expansion valve to the opening degree at that time is represented by the following equation and is plotted on the horizontal axis.

[0036]

[Equation 1]

Since the expansion valve has an appropriate opening only when the amount of refrigerant is appropriate, it is determined that the amount of refrigerant is appropriate when the expansion valve has an appropriate opening. Therefore, S = 1
In this case, the ratio of the amount of refrigerant at that time and the appropriate amount of refrigerant must still be 1. Then, the opening degree of the expansion valve and the refrigerant amount are in a substantially inversely proportional relationship. That is, when the refrigerant amount is larger than the proper refrigerant amount, the opening degree of the expansion valve becomes smaller than the proper opening degree. On the other hand, when the refrigerant amount is smaller than the proper refrigerant amount, the opening degree of the expansion valve becomes smaller than the proper opening degree.

Therefore, the ratio of the amount of the refrigerant at that time to the appropriate amount of the refrigerant is calculated by the following equation, and is taken on the vertical axis.

[0039]

[Equation 2] S ₁ = 2-S (Equation 2)

[0040]

(Equation 3)

S₁ Is represented by a straight line like the solid line in FIG.
Be done. This calculation formula assumes that the inversely proportional relationship is a straight line to the right.
The relationship between the amount of refrigerant and the expansion blade valve opening is clear
Is a feature. However, in reality
Although it is a bad thing, the amount of refrigerant is too small.>S in case of 2₁ 
<It becomes 0 and becomes unreasonable.

S ₂ is represented by a curved line like the broken line in FIG. This calculation formula represents the inversely proportional relationship as a downward-sloping curve. In the range of excess and deficiency of practical refrigerant amount,
Since S ₁ and S ₂ have similar values, either one may be used. However, as the amount of excess and deficiency of the refrigerant increases,
The difference between S ₁ and S ₂ becomes large.

The result of calculating the refrigerant amount at the present time with respect to the proper refrigerant amount by the equations 1 and 2 by using the opening of the expansion valve may be used as it is as the refrigerant amount determination result, but in order to further improve the determination accuracy. In addition, it is advisable to perform various corrections based on cycle specifications and state quantities. This includes the discharge pressure and suction pressure of the compressor and the operating level of the condenser, as described in FIG. Further, there are pipe length, capacity characteristics of sliver, flow rate characteristics of expansion valve, wind speed of fan of evaporator and the like. As one example, two corrections, one relating to the discharge pressure of the compressor and the other relating to the capacity characteristic of the receiver, will be described.

With respect to the discharge pressure of the compressor, the number of revolutions of the compressor is controlled by the feedback control function shown in FIG. 2 to control the discharge pressure to its target value. However, the target value is not always controlled to this target value. Therefore, in such a case, the rotation speed of the compressor should be corrected by the calculation mechanism so that the discharge pressure becomes smaller in accordance with the deviation of the discharge pressure from the target value, but this has been realized. If not, the correction amount of the rotation speed corresponding to this is calculated in the same manner as the calculation mechanism 23. By referring to the relation table using the rotation speed corrected in this way,
The proper opening degree of the expansion valve is also corrected. As a result, the relationship tables shown in FIGS. 6 and 7 can be used more strictly in accordance with the cycle state, so that the determination accuracy is improved.

The receiver has a capacity to store the liquid refrigerant to some extent. Therefore, even if the amount of refrigerant increases or decreases from the proper amount of refrigerant, as long as the amount of refrigerant changes within the range of the capacity of the receiver, it does not clearly appear as a change in the cycle state. In FIG. 10A, the horizontal axis represents the change in the refrigerant amount with the proper refrigerant amount as 1, and the vertical axis represents the refrigerant amount in the receiver. Figure 10 (b)
Shows the change in the refrigerant amount with the proper refrigerant amount as 1, and the vertical axis represents the ratio of the expansion valve opening to the appropriate opening of the expansion valve.

As shown in FIG. 10 (a), if the refrigerant is stored in a proper amount of refrigerant up to about the middle of the receiver, the cycle state is maintained even if various load conditions and operating conditions change. Since it can be controlled so as to be maintained normally, it is considered to be advantageous in terms of reliability. Then, in the range where the amount of refrigerant is substantially centered around this, the refrigerant can be stored more or less in the receiver, and the amount of refrigerant in the receiver tends to increase and decrease as the amount of refrigerant increases and decreases. At this time, FIG. 10 (b)
As shown in, the opening of the expansion valve does not change much. That is, it can be seen that the inversely proportional relationship between the refrigerant amount and the expansion valve opening degree is established, but its influence is very small.
It can be said that this is the reason for providing the receiver. On the other hand, in the range b where the refrigerant amount is insufficient and the receiver does not store the refrigerant, the feedback control shown in FIGS. 2 and 3 works so that the opening degree of the expansion valve rapidly increases as the refrigerant amount decreases. .

Further, in the range of C where the refrigerant overflows from the receiver due to an excessive amount of refrigerant, feedback control works so that the opening of the expansion valve suddenly decreases as the amount of refrigerant increases. In this way, when the excess or deficiency of the refrigerant amount increases from the appropriate amount of refrigerant, the sensitivity of the relationship in direct proportion between the refrigerant amount and the expansion valve opening increases.

Therefore, by adding the correction of the non-linear function as shown in FIG. 10B to the linear inversely proportional relationship of FIG. 9, it becomes possible to more accurately determine the refrigerant amount.

The determination result S ₁ or S ₂ of the refrigerant amount by the refrigerant amount calculation mechanism 51 can be displayed as a numerical value on the display 42 using 7 segments or the like at predetermined time intervals. However, in this case, the determination result may vary at each time interval, which may make it difficult for the operator to confirm. Therefore, as shown in FIG. 11, S ₁ or S ₂ is divided stepwise and each is displayed by a symbol.
When S ₁ or S ₂ is divided into ranges such as A, B, C, D and E, A is an excessively small amount of refrigerant, B is slightly small, C is an appropriate amount of refrigerant, D is slightly large, and E is an amount of refrigerant. It is possible to deal with the phenomenon of excess, so it is easier to understand by displaying with a symbol that expresses this word.

Further, it is an effective method to suppress the variation of the determination result and increase the accuracy of the display by performing statistical processing on the determination result. FIG. 12 shows the statistical processing function 52.
3 is a flowchart illustrating the operation of the above. First, (G)
Inputs the present determination result S ₅ . Next, (H) the average value S of the determination results S _i at the five points up to the present time is calculated.
Then, (I) this is output to the display 42 and stored in the memory 53. It is convenient for the operator to check the determination result stored in the memory 53 so that the determination result can be read when necessary. In addition, when the individual judgment results greatly vary, this is judged from the distribution of the judgment results, and when the contents cannot be displayed on the display 42 by the judgment impossible display mechanism 54, the operator can confirm this. It is convenient because you can do it. Needless to say, the statistical processing method and parameters described above can be appropriately selected.

The refrigerant amount determination means 39 of the present invention is started and stopped by using the manual switch 41. Alternatively, a manual switch is used to start and stop the unique automatic operation mode for determining the amount of refrigerant, and further stop and start the refrigerant amount determination means 39 together. Depending on the specific operation mode for judging the amount of refrigerant, either cooling or heating operation is selected, the operation of the indoor unit is stopped, the set value of the indoor temperature, the setting of the wind speed of the indoor unit, etc. are specified. Operate under the conditions. FIG. 13 shows operating ranges of heating and cooling of the multi-room air conditioner.

Taking the room temperature on the horizontal axis and the outside air temperature on the vertical axis,
The range of the solid line shows the operating range in which heating is possible, and the range of the broken line shows the operating range in which cooling is possible. In order to increase the accuracy of the refrigerant amount determination, it is not preferable to allow all these operations. Especially when the outside temperature is low,
In the heating operation when the outside air temperature is high, the state of the cycle is largely biased, and the correlation between the refrigerant amount and the opening degree of the expansion valve is lost, so that the determination accuracy of the refrigerant amount decreases. Therefore, it is better to operate with the unique setting such as cooling when the outside temperature is high and heating when the outside temperature is low, with the outside temperature indicated by the one-dot chain line as the boundary.

Similarly, all the indoor units are operated to increase the room conditioning load. As a result, the cycle constantly continues the high output state, and the determination result of the refrigerant amount becomes stable. At this time, if the set value of the indoor temperature is set to the maximum value for heating and the minimum value for cooling, the room temperature is not set to the set value and the indoor unit is less likely to stop. As a result, the cycle also continues to constantly maintain a high output state, and the determination result of the refrigerant amount becomes stable. Also, regarding the wind speed of the indoor unit,
It is preferable to set a large value.

This makes it possible to match the operation mode in which the relationship tables shown in FIGS. 6 and 7 are created in advance with the operation mode for determining the refrigerant amount in various multi-room air conditioners at various places. It will be possible. Therefore, the accuracy of determining the amount of refrigerant can be significantly improved.

FIG. 14 is a schematic diagram showing an implementation of the refrigerant amount determination device 39 of the present invention. The control device 19 for the multi-room air conditioner shown in FIGS. 2 and 3 is usually mounted inside the outdoor unit 1. Therefore, it is convenient to mount the refrigerant amount determination device 39 related thereto as well inside the outdoor unit 1. Further, it is possible to realize them on the same substrate by using the same microcomputer. In this way, the whole device can be compact and can be assembled at low cost, but the operability and display contents are not limited. On the other hand, the controller 19 and the signal line 56
There is also a method in which the refrigerant amount determination device 39 is externally attached to the outdoor unit 1 by exchanging information by using. The figure shows an example in which this is realized using a personal computer. With this configuration, the function of the personal computer can be effectively used, and therefore, in addition to the refrigerant amount determination means 40, the collection and recording of the state quantity and the operation quantity related to the cycle, the automatic diagnosis function based on the collection and recording, and the like. It can be used as a powerful support tool for workers as it can add report printing.

[0056]

According to the present invention, it is possible to quantitatively judge and display the excess or deficiency of the refrigerant amount with respect to the appropriate refrigerant amount without newly adding a special detector for judging the refrigerant amount. Therefore, the cost of the detector and the like can be reduced as compared with the conventional method.

Further, the operator can easily obtain a highly accurate and stable determination result without requiring a special device or work for determining the refrigerant amount. As a result, the additional charging and discharging of the refrigerant can be performed accurately and efficiently, resulting in a significant time and cost saving effect.

[Brief description of drawings]

FIG. 1 is a system diagram of a multi-room air conditioner.

FIG. 2 is a block diagram of a control device for a multi-room air conditioner.

FIG. 3 is a block diagram of a control device for a multi-room air conditioner.

FIG. 4 is an explanatory diagram of a cycle showing the principle of refrigerant amount determination.

FIG. 5 is a block diagram of a refrigerant amount determination device.

FIG. 6 is an explanatory diagram showing the contents of a relationship table.

FIG. 7 is an explanatory diagram showing the contents of a relationship table.

FIG. 8 is a flowchart showing the function of stability determining means.

FIG. 9 is a characteristic diagram showing a method of refrigerant amount calculation.

FIG. 10 is a characteristic diagram showing a method of calculating a refrigerant amount.

FIG. 11 is a characteristic diagram showing a determination display method.

FIG. 12 is an explanatory diagram of an operation for determining a refrigerant amount.

FIG. 13 is an explanatory diagram of an operating method for determining the refrigerant amount.

FIG. 14 is an explanatory diagram of an operating method for determining the refrigerant amount.

[Explanation of symbols]

40 ... Refrigerant amount determination means, 41 ... Switch, 42 ... Indicator, 43 ... Condenser, 44 ... Expansion valve, 45 ... Evaporator, 46
... Fan, 47 ... Relation table, 48 ... Relation table selection mechanism, 49 ... Relation table reference mechanism, 50 ... Stability determination mechanism, 51 ... Refrigerant amount calculation mechanism, 52 ... Statistical processing mechanism, 5
3 ... storage memory, 54 ... non-determination display mechanism.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shinichiro Yamada 390 Muramatsu, Shimizu-shi, Shizuoka Hitachi Air Conditioning Systems Division (72) Inventor Kenichi Nakamura 390, Muramatsu Shimizu, Shizuoka Hitachi Air Conditioning Systems Co., Ltd. (72) Inventor Satoru Yoshida 390 Muramatsu, Shimizu City, Shizuoka Prefecture Hitachi, Ltd. Air Conditioning Systems Business Unit

Claims (1)

[Claims] 1. A capacity variable compressor having one outdoor unit and a plurality of indoor units, at least one of which has a variable rotation speed, an outdoor heat exchanger, and an outdoor expansion unit. Valve,
An outdoor fan having a variable rotation speed is provided, and each indoor unit is provided with an indoor heat exchanger, an indoor expansion valve, and an indoor fan having a variable rotation speed. In the multi-chamber air conditioner that constitutes, during heating, the total number of revolutions of the compressor when operating with a proper amount of refrigerant enclosed and the wet-bulb temperature of the intake air of the outdoor heat exchanger or the evaporation temperature of the refrigerant. The relational data of the total appropriate opening degree of the outdoor expansion valve is stored in advance, and the total rotation speed of the compressor at that time and the wet-bulb temperature of the intake air of the outdoor heat exchanger or the evaporation temperature of the refrigerant are stored. Based on the relationship between the total appropriate opening degree of the outdoor expansion valve and the total opening degree of the outdoor expansion valve at that time, and also during cooling, the compressor when operating by enclosing a proper amount of refrigerant. Total speed and indoor heat exchange The relational data of the average wet bulb temperature of the intake air or the average temperature of the blown air and the total appropriate opening of the indoor expansion valve is stored in advance, and the total rotation speed of the compressor at that time and the above Based on the relationship between the average wet bulb temperature of the intake air of the indoor heat exchanger or the average temperature of the blown air, the total appropriate opening of the indoor expansion valve, and the total opening of the indoor expansion valve at that time. ,
A refrigerant amount determination device, which displays whether the ratio of the amount of refrigerant at that time to the amount of appropriate refrigerant or whether the amount of refrigerant at that time is appropriate or unsuitable for the appropriate amount of refrigerant is determined and displayed at predetermined time intervals during a predetermined time.