JP3347441B2 - Control device for air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an air conditioner, and more particularly, to a target discharge temperature of a compressor.
Quickly achieves discharge superheat despite simple configuration
And maintain stable irrespective of changes in operating conditions
A control equipment suitable air conditioner for.

[0002]

2. Description of the Related Art Conventionally, as a control device for controlling and adjusting a discharge temperature or a discharge superheat degree of a compressor, Japanese Patent Application Laid-Open No.
No. 3065, Japanese Patent Application Laid-Open No. 62-119370, and the like have been proposed.

Japanese Patent Application Laid-Open No. 60-263065 discloses a refrigerant circuit comprising a compressor, a condenser, an electronic linear expansion valve, an evaporator, and an accumulator, a means for detecting a saturation temperature of a refrigerant of this circuit, and a means for detecting a suction temperature. Means for calculating the degree of superheat from the detected temperature and temperature signals from both means, and determining which of the plurality of areas around the predetermined appropriate degree of superheat is the degree of superheat calculated by this means. Means for adding a predetermined correction value that differs depending on whether the degree of superheat is in the above-described region to the current valve opening, or determining the valve opening to a value obtained by subtracting the same from the current valve opening, and valve opening determined by this means. Means for controlling the degree of opening of the electronic linear expansion valve at each time, the detection, calculation, determination, determination and control by these means are performed at predetermined time intervals so that the degree of superheat is within a predetermined range. A control method of the refrigeration cycle consisting of configuration Gosuru.

In the control method of the refrigeration cycle,
The opening control of the LEV in the refrigeration cycle is performed by determining which of the plurality of regions around the appropriate region the superheat degree is, and adding a different correction value to the current valve opening according to the determination result, or The LEV is controlled by determining the valve opening degree by reducing it, so that the appropriate valve opening degree is reached quickly and smoothly, and even when the compressor capacity is controlled or the air condition inside and outside is changed, the optimal overheating is always performed. It has the effect of enabling high-efficiency operation at different degrees.

Japanese Patent Application Laid-Open No. Sho 62-119370 discloses a refrigeration apparatus having a refrigerant circulation circuit in which a compressor, a condenser, a decompression mechanism, and an evaporator are sequentially connected. An operation mode detecting means for detecting a current operation mode, comprising an electrically operated valve connected in series, and receiving an output of the operation mode detection means so that the superheat degree becomes substantially a predetermined value according to the current operation mode. A refrigerating apparatus comprising a control means for performing open-loop control of the electric valve to a predetermined fixed opening degree.

In the refrigeration system, an electric valve is connected in series with the pressure reducing mechanism of the refrigerant circuit, and the opening of the electric valve is controlled in an open loop to a fixed opening determined in advance according to the operation mode. It is possible to greatly simplify the opening degree control system of the motor-operated valve while always maintaining the superheat degree of the refrigerant at a predetermined value irrespective of the mode change, and to reduce the refrigerant passage noise when the pressure of the refrigerant is largely reduced. It has an effect that can be done.

[0007]

According to the former prior art, the discharge temperature or discharge superheat of the compressor is adjusted in accordance with the deviation between the detected value of the temperature detector and the target value so that the discharge temperature or the discharge superheat degree matches the target value. It is based on the principle of feedback control of determining the degree of opening of the expansion valve. In this method, since the detected value is constantly monitored, it has a feature that it can quickly and smoothly follow a change in the capacity of the compressor or a change in the air condition inside and outside the room. However, for this purpose, there is a problem that the control constant of the feedback control must be appropriately determined so as to be suitable for each operation mode. In order to solve this problem, the latter conventional technique has been proposed.

In the latter prior art, the expansion valve is controlled to a fixed opening determined in advance according to the operation mode so that the discharge temperature or discharge superheat of the compressor matches the target value. It is based on the principle of loop control. This method is characterized in that the target value can always be held irrespective of the change in the operation mode, and the control system is only one-way, so that it can be greatly simplified. However, for this purpose, there is a problem that the fixed opening of the expansion valve must be determined in advance according to the operation mode.
If the fixed opening is incorrectly selected, not only the target value cannot be achieved and maintained, but also a stable cycle operation state cannot be maintained. Therefore, in order to adopt this method, there is a problem on the premise that the fixed opening of the expansion valve is appropriately determined.

The present invention has been made in view of the above-mentioned problems of the prior art,
An air conditioner that can quickly achieve a target discharge temperature or discharge superheat degree of a compressor despite a simple configuration and that can stably maintain regardless of a change in an operation state. It is an object to provide a control device.

[0010]

To achieve the above object, the present invention provides an outdoor unit having a compressor, an outdoor fan and an outdoor heat exchanger, an expansion valve having a variable opening degree, an indoor fan and an indoor heat exchanger. consists of a comprising a vessel indoor unit, the control unit of the sequential coupling air conditioner which constitutes a cooling cycle or heating cycle, (1) a predetermined discharge temperature or the discharge superheat expansion valve of the compressor The relationship with the opening is stored in advance with hysteresis in the opening increasing direction and the opening decreasing direction in stages.
First control means for determining the expansion valve so as to correspond to the discharge temperature or the discharge superheat of the compressor detected through the detector in response to the stored contents, the discharge (2) the compressor Predetermined temperature or discharge superheat
If the discharge temperature is in the direction stably realized within the range,
Ku is a second control means for correcting the expansion valve opening determined by the predetermined shift amount in <br/> said first control means the relationship between the discharge superheat expansion valve opening, (3) the Expansion valve opening determined by first control means
Of two expansion valves have exceeded the threshold value
The discharge temperature or discharge superheat of the compressor
A third control means for activating the second control means upon determining that it is in a constant state ; and (4) the first control means according to a correction result of the second control means.
And a fourth control means for correcting the storage content of the control means.

[0011]

With the above configuration, first, the first control means uses an appropriate relationship between the discharge temperature or discharge superheat degree of the compressor and the degree of opening of the expansion valve, which is stored in advance, and
Open-loop control of the expansion valve opening is performed in accordance with the discharge temperature or discharge superheat of the compressor detected through the detector. For this reason, the target discharge temperature or discharge superheat degree can be quickly achieved by a simple control system configuration.

According to the control result of the first control means, the discharge temperature or discharge superheat degree of the compressor becomes the third temperature .
Is determined to be not stably realized within the predetermined range by the control means (specifically, determined by the first control means
Of the two expansion valve openings out of the set expansion valve opening
When the threshold is exceeded, the discharge temperature of the compressor or
If the discharge superheat is determined) as unstable state, as the discharge temperature or the discharge superheat of the compressor by the second control means it is stably implemented in Jo Tokoro range, first Feedback control of the expansion valve opening degree determined by the control means (the discharge temperature or discharge superheat degree and the expansion valve
The relationship with the opening is shifted by a predetermined amount) . This facilitates the selection of the fixed opening degree of the expansion valve used for the first control means, and can easily follow a change in the compressor capacity control and a change in indoor and outdoor air conditions.

Also, the second control means itself is based on the assumption that the state near the target value has been achieved by the first control means, so that it is easy to select a control constant.

Furthermore, the fourth control means controls the second
Since the storage content of the first control means is corrected based on the correction result by the control means, the control performance of the first control means is gradually improved. In addition to making it easier to select the fixed opening of the expansion valve used for the control means, controlling the capacity of the compressor and changing the indoor and outdoor air conditions unexpectedly large, and even if it differs from the design, In this case, it is possible to respond quickly.

[0015]

EXAMPLES Hereinafter, a description will be given of an embodiment of the present invention with reference to FIGS. 1 is a diagram showing a configuration of a control device of the air conditioner, FIG. 2 is a block diagram showing a configuration of the control device of FIG. 1, and FIG. 3 is a diagram showing a relationship between a discharge temperature or discharge superheat degree of a compressor and an expansion valve opening degree. 4 is a time chart for explaining the control operation, FIG. 5 is a flowchart showing the control operation of the second control means, FIG. 6 is a frequency distribution diagram of the occurrence frequency of the valve opening, and FIG. FIG. 8 is a view showing an example of a correction result of a relationship between a discharge temperature or a degree of superheat of the machine and the degree of opening of the expansion valve, and FIG.

In FIG. 1, reference numeral 1 denotes a compressor having a fixed or variable rotation speed, 2 a four-way valve for switching the direction of refrigerant flow during cooling and heating, 3 an outdoor heat exchanger, and 4 an outdoor fan. It becomes a condenser during cooling, and an evaporator during heating. Reference numeral 5 denotes an expansion valve with a variable opening, 6 denotes an indoor heat exchanger, 7 denotes an indoor fan, which serves as an evaporator for cooling and a condenser for heating. 8 is an accumulator. Reference numeral 9 denotes a control device which inputs a detection value of a detector 10 for detecting a discharge temperature or a discharge superheat degree of the compressor, and controls an opening degree of the expansion valve 5. At the time of cooling, the refrigerant flows in the direction of the arrow shown in the figure, and at the time of heating, flows in the opposite direction. The control is the same for both cooling and heating, but in the following description, the case of cooling will be described.

In FIG. 2, the control device 9 shown in FIG. 1 is surrounded by a dotted line. 11 is the first control means, 12 is the second control means.
, 13 is third control means, 14 is fourth control means, 15 is first control means 11 and second control means 12
Switching means for switching the output by the third control means 13, 16 is an opening controller of the expansion valve 5, 17 is a rotation speed control means of the compressor 1, 18 is a refrigeration cycle shown in FIG. It is a numerical controller. The opening degree of the expansion valve 5 is controlled by an opening degree controller 16 based on the output of the switching means 15, and the rotation speed of the compressor 1 is controlled by a rotation speed control means.
Controlled by the speed controller 19 based on the output of the stage 17
Thus, the operating state of the refrigeration cycle 18 is controlled.

The first control means 11 stores in advance the relationship between the proper discharge temperature or discharge superheat degree of the compressor 1 and the opening degree of the expansion valve 5, and discharges the compressor 1 discharge temperature or discharge superheat. The opening degree of the expansion valve 5 is directly determined and controlled according to the discharge temperature or the discharge superheat degree detected by the detector 10 for detecting the degree. In order to implement a simple method based on the principle of such open loop control, it is necessary to improve control stability in a method of storing the above relationship and a method of realizing the opening of the expansion valve 5.

For this purpose, an appropriate relationship between the discharge temperature or discharge superheat degree of the compressor 1 and the opening degree of the expansion valve 5 as shown in FIG. 3 is stored in advance. The horizontal axis in FIG. 3 is the discharge temperature or superheat degree T ₀ of the compressor 1, and the vertical axis is the opening degree V of the expansion valve 5.
Is shown. The relationship between these two variables is basically displayed on a one-to-one basis according to the capacity of the air conditioner, but varies depending on the operating state of the compressor and the heat exchanger. That is, the rotation speed of the compressor, the outside air temperature indicating the load on the outdoor heat exchanger, the evaporation temperature indicating the operation state, the condensation temperature, the room temperature indicating the load on the indoor heat exchanger, the evaporation temperature indicating the operation state, the condensation temperature, etc. Change.

At this time, if each adjustment is made in accordance with the discharge temperature or the discharge superheat, the opening of the expansion valve 5 changes too frequently, which is not preferable from the viewpoint of the stability of the operation state. In order to take advantage of the characteristics of the open loop control using such a simple relationship, the discharge temperature or discharge superheat degree of the compressor 1 and the opening degree of the expansion valve 5 shown in FIG. Is stored in a stepwise manner, with hysteresis in the direction in which the opening increases and in the direction in which the opening decreases. That is, within a predetermined range of the discharge temperature or discharge superheat degree of the compressor 1,
The opening degree of the expansion valve 5 is not changed, and further, the discharge temperature or the discharge superheat degree increases and the opening degree of the expansion valve 5 increases, and conversely, the discharge temperature or the discharge superheat degree decreases. Thus, there is a width in the case where the opening degree of the expansion valve 5 is reduced. Thus, unless the operating state of the compressor 1 or the heat exchanger changes significantly, the opening of the expansion valve 5 does not change frequently, and a stable state based on this relationship is maintained.

Further, there is an effect on manufacturing that a memory capacity for storing the above relationship is small, so that it is practical. Further, if such a relationship is established, there is also a design effect that a wide range of changes in operating conditions can be absorbed without requiring such a precise accuracy. Therefore, usually, such control means is sufficient.

However, even if the above control means is provided,
Depending on the degree of change in the operating state, it may be assumed that the change cannot be absorbed. FIG. 4 shows an example of such a case, in which time is plotted on the horizontal axis, and changes in the discharge temperature or discharge superheat of the compressor 1 and the corresponding control results of the opening of the expansion valve 5 are shown. When controlled using the relationship of FIG. 3, when the discharge temperature or the discharge superheat of the compressor 1 as shown in FIG. 4 (a) is largely changed from T ₃₁ to the width of the T _32, the expansion valve as this 5 for opening also V ₃ and V ₄ 2 two values alternately take such unstable and the is likely to occur continuously. In such a case, the relationship in FIG. 3 can be easily stabilized by correcting the relationship by the second control unit 12 described later.

Before the correction by the second control means 12, it is determined by the third control means 13 shown in FIG. 2 whether the correction is necessary. This determination operation is shown in FIGS.
This will be described with reference to FIG. The determination operation is started every control cycle of the expansion valve 5. Then, to create a frequency distribution as shown in FIG. 6 (b) by counting the frequency of valve opening of each time point as shown in FIG. 6 (a). When the refrigeration cycle is stable, only a specific one valve opening is held for a long time, so that the frequency of occurrence of only one specific valve opening exceeds the threshold value Nmax when divided by a predetermined time. Also, when the refrigeration cycle is transitioning transiently, the valve opening changes variously. At this time, if the interval is divided by a predetermined time, the frequency of occurrence of the valve opening varies with some valve opening .

As shown by the solid line in FIG.
When two valve openings are repeated, the frequency of occurrence of the two valve openings exceeds the threshold value Nmax when the two valve openings are separated by a predetermined time. In this case, it is determined that the state is unstable,
The valve opening is corrected by the second control means 12 as shown by the dotted line in FIG. Here, the correction by the second control means 12 corrects the opening degree of the expansion valve 5 based on the control result of the first control means 11 so that the discharge temperature or discharge superheat degree of the compressor 1 falls within a predetermined range. To be realized stably. As a specific countermeasure, there is a simple method of correcting the opening of the expansion valve 5 so as to be an intermediate value between the two values. This makes it possible to escape from a state in which the discharge temperature or discharge superheat degree of the compressor 1 greatly fluctuates due to the difference between the degrees of opening of the two expansion valves 5. This is Figure 4
(B) a as indicated by the dotted line, the opening degree of the expansion valve 5, has taken exactly intermediate value of V ₃ and V _4, thereby the compressor 1
The discharge temperature or the discharge superheat, as well as indicated by a dotted line in FIG. 4 (a), becomes the intermediate value between T ₃₁ and T _32, it is possible to reduce the variation state.

The above countermeasures correspond to shifting the relationship between the discharge temperature or discharge superheat of the compressor 1 and the opening of the expansion valve 5 upward or downward by a predetermined amount. Other methods include shifting this relationship to the left or right by a predetermined amount , a temperature range or a valve.
How to increase or decrease the width of the opening ,
There is a method of using these methods in combination. Whichever method is used, the discharge temperature or discharge superheat of the compressor 1 is
The degree of opening of the expansion valve 5 is corrected in a direction stably realized within a predetermined range, and the correction is ended when it is determined that the opening is within the predetermined range.

The above-mentioned correction by the second control means 12 is effective in the operation state shown by the solid line in FIG. 4, but the same correction is often required throughout the operation state. In such a case, the contents stored in the first control means 11 are corrected (corrected) by the fourth control means 14 based on the correction result by the second control means 12.

FIG. 7 shows an example of the correction result. FIG.
(A) is based on the relationship between T ₀ and V shown in FIG. 3,
This is an example in which the opening degree of the expansion valve 5 with respect to the discharge temperature or discharge superheat of the compressor 1 is corrected to be shifted upward. This corresponds to applying the correction contents shown in FIG. 4 throughout the entire operation state. Further, FIG. 7 (b) based on the relationship between T ₀ and V shown in FIG. 3 as well, the discharge temperature or the discharge superheat of the compressor 1, the right side with respect to the opening degree of the expansion valve 5 This is an example in which correction is made to shift to. Thus, again stores the result of the correction by the fourth control unit 14, thereafter, it is controlled by the first control means 11 based on the stored contents. For this reason, a stable operating state can be realized over a wide range of the discharge temperature or discharge superheat of the compressor 1.

FIG. 8 is a flowchart showing the control operation of the fourth control means 14. Based on the content of the correction made to the specific valve opening in the second control means 12,
The relationship between the discharge temperature or discharge superheat degree of the compressor 1 shown in FIG. 3 and the expansion valve 5 stored in the first control means 11 is corrected and stored in the first control means 11.

FIG. 8A shows an example in which the second control means 12 corrects the relationship between the discharge temperature or discharge superheat degree of the compressor 1 shown in FIG. is there. Here, when the relationship is corrected upward, the correction is performed so that the relationship shown in FIG.

FIG. 8B shows the second control means 12.
In this example, the relationship between the discharge temperature or the degree of superheat of the compressor 1 shown in FIG. 3 and the expansion valve 5 is corrected rightward or leftward. Here, when the relationship is corrected to the right, the correction is performed so that the relationship shown in FIG. 7B is obtained.

[0031]

As described above, the present invention has a simple structure by a control means based on an open loop control based on a relation between a proper discharge temperature or discharge superheat degree of a compressor and an opening degree of an expansion valve. Regardless, the target discharge temperature or discharge superheat of the compressor can be achieved quickly.

Further, the target discharge temperature or discharge superheat degree of the target compressor can be stably maintained irrespective of a change in the operating state by adjustment based on feedback control for compensating and complementing the above relationship and learning control means. It becomes possible to do.

Further , these functions enable each control means to operate.
The effect that the trouble of a design and adjustment can be reduced is produced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a control device of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a control device in FIG. 1;

FIG. 3 is a diagram showing an appropriate relationship between a discharge temperature or a discharge superheat degree of a compressor and an opening degree of an expansion valve.

FIG. 4 is a time chart for explaining a control operation of first and second control means.

FIG. 5 is a flowchart showing a control operation of a second control means.

FIG. 6 is a frequency distribution diagram of the frequency of occurrence of valve opening.

FIG. 7 is a diagram illustrating an example of a correction result of a relationship between a discharge temperature or a discharge superheat degree of a compressor and an expansion valve opening degree.

FIG. 8 is a flowchart showing a control operation of a fourth control means.

[Explanation of symbols]

1 ... Compressor, 3 ... Outdoor heat exchanger, 4 ... Outdoor fan, 5 ...
Expansion valve, 6 indoor heat exchanger, 7 indoor fan, 8 accumulator, 9 control device, 10 detector, 11 first
Control means, 12 ... second control means, 13 ... third control means, 14 ... fourth control means, 15 ... switching means, 1
6 ... Opening degree controller, 17 ... Rotation speed control means , 18 ... Refrigeration cycle, 19 ... Rotation speed controller .

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F25B 1/00 F24F 11/02 102

Claims (1)

(57) [Claims] 1. An outdoor unit comprising a compressor, an outdoor fan and an outdoor heat exchanger, and an indoor unit comprising a variable-opening expansion valve, an indoor fan and an indoor heat exchanger, which are sequentially connected. the control device for an air conditioner which constitutes a cooling cycle or heating cycle Te, (1) the relationship between the expansion valve to a predetermined discharge temperature or the discharge superheat of the compressor, in advance stepwise opening increasing direction And memorize it with hysteresis in the direction of opening decrease,
First control means for determining the expansion valve so as to correspond to the discharge temperature or the discharge superheat of the compressor detected through the detector in response to the stored contents, the discharge (2) the compressor Predetermined temperature or discharge superheat
If the discharge temperature is in the direction stably realized within the range,
Ku is a second control means for correcting the expansion valve opening determined by the predetermined shift amount in <br/> said first control means the relationship between the discharge superheat expansion valve opening, (3) the Expansion valve opening determined by first control means
Of two expansion valves have exceeded the threshold value
The discharge temperature or discharge superheat of the compressor
A third control means for activating the second control means upon determining that it is in a constant state ; and (4) the first control means according to a correction result of the second control means.
And a fourth control means for correcting the storage content of the control means.