JPH0336471A - Air conditioner - Google Patents

Abstract

PURPOSE:To properly control the opening of an electronic expansion valve by controlling the opening of said electronic expansion valve so that the dryness fraction of an indoor heat exchanger's outlet gas may be proper as a vaporizer during cooling operation and the subcooling of said indoor heat exchanger may be proper as a condenser during heating time. CONSTITUTION:The superheat SH at the outlet of a vaporizer 5 is calculated from the temperature data of temperature sensors 7 and 8 based on the equation SH = T8 - T7 during cooling operation. If SH >, the outlet of the vaporizer has superheat and indicates a dash of dryness. Therefore, it is possible to subtract a specified correction value a from the present opening of an electronic expansion valve 4 and determine a new opening. During heating the subcooling is calculated from temperature sensors 8 and 9 respectively. These calculated values are determined to see at which region they stay of these A, B, proper, C, and D. The specified correction values a and b are respectively added to the opening of the valve under the operation based on the result or correction values c and d are subtracted so that a new opening may be determined.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to an air conditioner, particularly a control method for an electronic expansion valve which is a pressure reducing device in its refrigeration cycle C. , for example, shows an example of a refrigerant circuit diagram of a conventional air conditioner disclosed in Japanese Patent Application No. 60-263065.

(Configuration) In the figure, l is a compressor, 3 is an outdoor heat exchanger, 4 is an electronic expansion valve with a throttling function, 5 is an indoor heat exchanger, and 6 is an accumulator for storing surplus refrigerant. They are sequentially connected by refrigerant pipes to form a refrigeration cycle. Reference numeral 15 denotes bypass pipes that communicate from the front and back of the electronic expansion valve 4 to the pipes connecting the indoor heat exchanger 5 and the accumulator 6. 7 is a temperature detector disposed on the bypass pipe 15, and 8 is a temperature detector (sensor) disposed on the pipe connecting the indoor heat exchanger 5 and the accumulator 6. It is.10
14 is a means for calculating the temperature difference from the temperature data from each temperature detector 7 and 8 and calculating the degree of superheating of the indoor heat exchanger outlet gas, and 14 is a means for determining the value of this degree of superheating. , 11 is a means for determining the opening degree of the electronic expansion valve 4 from the obtained superheat degree, and 12 is a means for controlling the opening degree of the electronic expansion valve 4 by driving. Also, superheat degree calculation means 10. Superheating degree determining means 14. The valve opening determining means 11 and the valve opening controlling means 12 are combined to form an electronic expansion valve control device 13.

(Operation) Next, the superheat degree control operation of the suction gas of the compressor during cooling in one or more configurations will be explained based on the sequence flowchart shown in FIG. 4 and the superheat degree timing chart shown in FIG. 5. FIG. 4 is a sequence flowchart of the program to be executed. First, at the start of the program, in step 41, a timer is set to set the control time interval t of the electronic expansion valve 4. Step 4
2, this timer counts the time, and when a predetermined set time t has elapsed, a time-up is detected in the next step 43, and furthermore, in the next step 44, each temperature sensor 7.8
The degree of superheat measurement is performed by reading the temperature signal input from the indoor heat exchanger 5 and calculating the degree of superheat of the log gas output from the indoor heat exchanger 5, that is, the suction gas of the compressor 1.

Next, this measured degree of superheat is determined by A and B in FIG.
, appropriate, C, or D is determined at each step 4.
5.46.47.48.49, and based on the results, predetermined correction values a, b are set for the valve opening S, -6 currently being output at each step 50°51.52, 53.54. is added or the correction values c and d are subtracted to determine a new control output valve opening degree Sj. Electronic expansion valve 4 and control device 1
3 has a linear relationship with the output opening degree SJ as shown in FIG. Further, if it is in the appropriate area, 5j-1 is directly determined as SJ, and the process proceeds to the next step 55.

In step 55, electronic expansion valve 4 determined by SJ
The opening degree of the electronic expansion valve control device 13 controls the opening degree of the electronic W strong valve 4, and the program returns to the initial stage of the program. Each of the above correction values has a relationship of a>b, d>c,
The closer to the appropriate area, the smaller the correction value is set.

For example, in the timing chart of the degree of superheat shown in FIG. 5, if there is a degree of superheat in region A at time 1o, a predetermined correction value a is added and the valve opening of the electronic expansion valve 4 is opened. As the valve opening degree of pre-expansion valve 4 becomes large, the degree of superheating decreases, and if the degree of superheating measured at 1 after time 1 reaches the D region, the valve opening degree of electronic expansion valve 4 is said to be too open. As a result, the correction value d is subtracted, and the valve opening of the electronic expansion valve 4 is closed. The magnitude relationship between the correction values a and d at this time is ad
This means d. Furthermore, if the degree of superheat is in region B at time t2, the correction value S is added this time, and the valve opening degree of the electronic expansion valve 4 is controlled by I. Naturally, the correction value is set to be a>b. At time t3, if there is superheat in region C, the correction value C is subtracted, and the valve opening of the electronic expansion valve 4 becomes ! ! 1 JIIl is done. Of course here d>
Let it be c. In this way, the valve opening degree of the electronic expansion valve 4 is controlled so that the degree of superheating finally falls within the appropriate range.

[Problems to be Solved by the Invention] However, the electronic expansion valve 4 in the conventional example was controlled so that the degree of superheat of the intake gas of the compressor was within a predetermined range, as described above. In a state where the amount of refrigerant charged in the air conditioner C is relatively large and surplus refrigerant is stored in the accumulator 6, it is difficult to provide a degree of superheat, and the amount of refrigerant charged in the air conditioner C is more than necessary to ensure an appropriate degree of superheat. There was a problem in that the valve opening was too narrow, causing operational problems.

This invention was made in order to solve the problems of the conventional example as described above, and even when the amount of refrigerant is such that surplus refrigerant is generated and it is difficult to impart a degree of superheat, it is possible to properly throttle the electronic expansion valve. The purpose is to provide an air conditioner that can be controlled.

(Means for solving LAW) Therefore, in the air conditioner according to the present invention, by controlling the opening degree of the electronic expansion valve used as a throttling function, indoor heat as an evaporator is The above objective is achieved by controlling the dryness of the exchanger outlet gas or, during heating operation, the subcooling (supercooling degree) of the outlet gas as a condenser to an appropriate value. It is something.

[Effect]

The air conditioner according to the present invention configured as described above uses an electronic expansion valve as a throttle, so that during cooling operation, the dryness of the outlet gas of the indoor heat exchanger serving as an evaporator is controlled, for example, by first adjusting the degree of superheat. After adjusting the opening of the electronic expansion valve so that the opening is exactly O, the electronic expansion valve is opened by a predetermined opening to control the opening to a more or less constant value, even in operations that generate surplus refrigerant. Stable control is performed without over-throttling.

Alternatively, during heating operation, for example, it is determined in which of a plurality of regions centered around a preset appropriate subcooling region the subcooling of the indoor heat exchanger outlet gas as a condenser is located, and the subcooling is By controlling the valve opening degree by adding or subtracting a predetermined correction value that differs depending on which region it is in to the current valve opening degree, the subcooling is operated at an appropriate value.

〔Example〕

The present invention will be explained below based on examples. FIG. 1 shows an embodiment of the refrigerant circuit of an air conditioner according to the present invention, and the same (equivalent) components as in the conventional example shown in FIG. 6 are denoted by the same reference numerals.

(Structure) In FIG. 1, 1 is a compressor, 2 is a four-way valve for switching between air conditioning and heating, and the solid line position is taken during cooling operation, and the dotted line position is taken during heating operation.

3 is an outdoor heat exchanger, 4 is an electronic expansion valve having a throttling function for pressure reduction, 5 is an indoor heat exchanger, and 6 is an accumulator, which are sequentially connected by refrigerant piping to form a refrigeration cycle. . 7.8° 9 is each temperature detector (sensor), which is located on the piping connecting the indoor heat exchanger 5 and the four-way valve 2, at the center of the indoor heat exchanger 5, and at the center of the indoor heat exchanger 5.
and the electronic expansion fP4 are arranged on a pipe that connects them.

Reference numeral 10 denotes a temperature difference calculation means which receives signals from each temperature sensor 7°8.9 as input data, and calculates the degree of superheating during cooling operation from the temperature detection results of each temperature sensor 7 and 8, and calculates each temperature. Based on the temperature detection results of the detectors 8 and 9, the subcool (supercooling degree) of the heating operation is calculated. Reference numeral 11 denotes a valve opening determining means for determining the valve opening of the electronic expansion valve 4 based on the superheat degree or subcooling data calculated by the temperature difference calculating means 10. 12 is a valve opening control means for directly driving and controlling the opening of the electronic expansion valve 4;
0.11.12 are combined to form the electronic expansion valve control device 13.

(motion) Next, operations in one or more configurations will be explained.

First, the operation of the refrigeration cycle will be explained with reference to FIG.

During cooling operation, the four-way valve 2 is located at the position indicated by the solid line in the figure, and the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 is condensed by exchanging heat in the outdoor heat exchanger @3, which acts as a condenser. It becomes a high-pressure liquid refrigerant, and is depressurized by the electronic expansion valve 4 to become a low-pressure two-phase refrigerant. Furthermore, the indoor heat exchanger 5 acts as an evaporator, where it evaporates into a two-phase refrigerant containing a small amount of superheated gas or liquid refrigerant, passes through the four-way valve 2, stores the surplus liquid refrigerant in the accumulator 6, and then the compressor l The cycle of being inhaled into the body is repeated.

On the other hand, in heating operation, the four-way valve 2 is located at the position indicated by the broken line in the figure, and the indoor heat exchanger I$5 is used as a condenser for the outdoor heat exchanger I$5.
The same cycle as in the cooling operation is repeated except that No. 3 acts as an evaporator.

During cooling operation, each temperature detector 7, 8 detects the evaporator ratio temperature T? , the evaporation temperature T6 is detected, and the degree of superheating is calculated by the following equation.

In the cell operation, each temperature detector 8.9 detects the condensation temperature Ta and the condensation amount outlet temperature T11, and the subtar is calculated by the following formula.

Subcool Tomi Ta-”r.

(1 Control Operation) Next, the operations for controlling the degree of superheating during cooling or the subcooling during heating are explained in the flowcharts shown in FIG. 2 and FIG. 4, and the control timing charts shown in FIGS. 5 and 7. The explanation will be based on. That is, Fig. 2,
The operation during cooling will be explained with reference to FIG. 5, and the operation during heating will be explained with reference to FIGS. 4 and 7. Here, it is assumed that the relationship between the electronic expansion valve 4 and the IIJ control device output opening degree S is a linear relationship as shown in FIG. 3 described above.

l) During cooling operation In FIG. 2, at the start of cooling operation, in step 21, the initial opening degree S0 of the electronic expansion valve 4 is set, and the opening degree output 5j-S of the valve opening control bag 3113 is set. do. In each step 22, 23, and 24, the refrigeration cycle completes the transient state after starting the cooling operation, and
Step 22) Set the time until stable operation is achieved as a timer 1. count.

During this time, the opening degree of the electronic expansion valve 4 is maintained at 5j=S. At each step 25, 26, and 27, the timer 2
As a result, the time interval of the opening degree control of the electronic expansion valve 4 becomes a predetermined time t.
In step 28, the temperature data Ta of the temperature sensor 7.8 is evaporated from Ta! The degree of superheating SH at the outlet of No. 15 is calculated by 5H-Ta-Tt. In step 29, SH is measured to be a positive or zero value and never negative.
If >0, the evaporator outlet has a degree of superheat and is a little dry, so the process proceeds to step 30 and the current electronic expansion valve opening degree S
Subtract the predetermined correction value a in the 's5 diagram from J-1,
Determine a new opening degree SJ. At this time, flag 1 is set in step 31. This new opening degree SJ is controlled by the electronic expansion valve control device 13 in step 32.

On the other hand, in step 29, if 5H-0, the process advances to step 33, and if flag 1 is set (F, -1), the process advances to step 34, where a predetermined correction value is set to the current function S J-1. A new step 21 with the addition of
+ Set +b. Furthermore, in step 35, the flag is reset to F, -0, and in step 36, flag 2 is set, making F2=1. Steps 33, 34, 35, 36
In this case, when the superheat degree SH>0 becomes 5H=0 for the first time, the opening degree step is further increased by the correction value from that valve opening degree. In step 33, if flag 1 is not set, the process proceeds to step 37, and if flag 2 is set here, the valve opening degree S is output as is in step 32. Step 37
If flag 2 is set in step 38
Then, the correction value C is subtracted from the current opening degree SJ-1, and a new opening degree SJ=Sj-, -c is output.

The operation achieved by the above operation is that in the initial state SH>
If it is 0, SH is decreased by increasing the valve opening degree Sj by the correction value a until 5H=O, and for the first time 5H=O.
When , the valve opening degree SJ is further increased by the correction value and held. Also, in the initial state 5) If I=O then SH>
The valve opening SJ is decreased by the correction value C until SH becomes O, and when SH>0 for the first time, the same operation as when the initial state becomes SH>O is performed.

2) During Heating Operation Next, the operation during heating will be explained based on the flowchart of FIG. 4 and the subcool control timing chart of FIG. 7. In the case of heating, the four-way valve 2 is located at the position indicated by the dotted line, and in FIG. 4, during heating, "superheat measurement" in step 44 is replaced with "subcool measurement."

FIG. 4 is a sequence flowchart of the program to be executed. First, at the start of the program, in step 41, a timer is set to set the control time interval t of the electronic expansion valve 4.

In step 42, this timer counts the time, and when a predetermined set time t has elapsed, a time-up is detected in the next step 43, and in the next step 44, subcool measurement is performed to calculate the subcool from each temperature sensor 8, 9. It will be done.

Next, the measured subcools are A and B.

Each step 4 determines whether the area is appropriate, C, or D.
5.4B, 47.48.49, and based on the results, predetermined correction values a, b are set for the valve opening S, -1 currently being output in each step 50, 51, 52°53.54. is added or the correction values c and d are subtracted to determine a new valve opening S, and if it is within the appropriate range, 5j-1 is determined as Sj, and the process proceeds to the next step 55.

In step 55, the valve opening determined by Sj is output, and the electronic expansion valve control bag @13 controls the valve opening of the electronic expansion valve 4, and the program returns to the beginning. The above correction values have the relationship a>b and d>c, and the closer the correction value is to the appropriate area, the smaller the correction value is set.

For example, in the subcool control timing chart shown in FIG. 7, if there is subcool in area A at time to, a predetermined correction value a is added and the valve opening of the electronic expansion valve 4 is opened. As the valve opening of the electronic expansion valve 4 increases, the subtar decreases, and if the subcool measured at tl after the time has reached the D region, the valve opening of the electronic expansion valve 4 is corrected because it is too open. The value d is subtracted and the valve opening of the electronic expansion valve 4 is closed. At this time, the correction value a,
The magnitude relationship of d is add. Furthermore, if the subcooling was in region B at time t, the correction value S is added this time, and the valve opening degree of the electronic expansion valve 4 is controlled. Assuming that the correction value naturally satisfies a>b, at time 0 t3, if there is subcooling in region C, the correction value C is subtracted, and the valve opening degree of the electronic expansion valve 4 is controlled. Naturally, it is assumed here that d>c. In this way, the valve opening degree of the electronic expansion valve 4 is controlled so that the subcooling finally falls within the appropriate range.

(Other Embodiments) In the above embodiments, an air conditioner is provided with a four-way valve 2 for switching between air conditioning and heating, and a temperature detector 9 is disposed on the inlet side of the indoor heat exchanger 5. ,next,
As another embodiment, the operation of the refrigeration cycle will be explained based on FIG. 6 and FIG. 2, in which the principles of the present invention are applied to the conventional configuration shown in FIG.

l〉Operation The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 is condensed by heat exchange in the outdoor heat exchanger 3, which acts as a condenser, and becomes a high-pressure liquid refrigerant, which is then depressurized by the electronic expansion valve 4 and reduced to a low pressure. It becomes a two-phase refrigerant.

Furthermore, the indoor heat exchanger 115 acts as an evaporator, where it evaporates into a two-phase refrigerant containing a small amount of superheated gas or liquid refrigerant, stores excess liquid refrigerant in the accumulator 6, and is sucked into the compressor 1. Repeat.

At this time, each temperature detection @7, 8 is the evaporation temperature Ty
, the compressor suction temperature T8 is detected, and the degree of superheat is calculated by the following equation.

Next, the control operation for controlling the degree of superheat will be explained based on the control sequence flowchart shown in FIG. 2.

Note that this control operation is exactly the same as the explanation in FIGS. 2 and 5 described in the section (Control operation) 1) Cooling operation in the first embodiment, so a repeated explanation will be omitted.

〔Effect of the invention〕

As explained above, according to the present invention, the dryness of the indoor heat exchanger outlet gas as an evaporator is set to an appropriate value during cooling, and the subcooling of the indoor heat exchanger outlet gas as a condenser is set to an appropriate value during heating. Since the opening degree of the electronic expansion valve is controlled so that the opening degree of the electronic expansion valve is controlled so that the opening degree of the electronic expansion valve is
14 It was possible to provide an air conditioner that can control the opening degree of the electronic expansion valve to a positive opening degree.

[Brief explanation of drawings]

FIG. 1 is a refrigerant circuit of an air conditioner according to an embodiment of the present invention, FIG. 2 is a control sequence flowchart according to this embodiment, and FIG. 3 is a diagram showing the opening degree of the electronic expansion valve and the control device output opening degree Sj. FIG. 4 is a diagram showing the relationship between the superheat degree and the conventional example.
J control sequence flowchart and subcooling sequence control flowchart of this embodiment (replacing step 30), FIG. 5 is a timing chart of conventional superheat degree control, FIG. 6 is an example of a conventional refrigerant circuit, and FIG. teeth,
It is a timing chart of subcool control of a present Example. 1 is a compressor, 2 is a four-way valve, 3 is an outdoor heat exchanger, 4 is an electronic expansion valve, 5 is an indoor heat exchanger, 6 is an accumulator, 7,
8.9 is a temperature detector, 10 is a temperature difference calculation means, 11 is a valve opening determining means, 12 is a valve opening control means, 13 is an electronic expansion valve control device, and 14 is a superheat degree determining means. Note that in each figure, the same reference numerals indicate the same or equivalent components.

Claims (2)

[Claims] (1) A refrigerant circuit consisting of a compressor, a four-way valve, an outdoor heat exchanger, an electronic expansion valve, an indoor heat exchanger, and an accumulator, each arranged on the center, outlet, and inlet pipes of the indoor heat exchanger. Each temperature detector, a temperature difference calculating means for calculating the degree of superheat of the indoor heat exchanger outlet gas during cooling and the subcooling of the outlet gas during heating from the signals from each temperature detector; Valve opening degree determining means for determining the valve opening degree of the electronic expansion valve from the calculated degree of superheat or subcooling, and valve opening degree control means for controlling the electronic expansion valve to the determined valve opening degree. The dryness of the compressor suction gas is controlled to predetermined values during cooling, and the subcooling of the suction gas is controlled to predetermined values during heating by controlling each of the means at predetermined time intervals. air conditioner. (2) A refrigerant circuit consisting of a compressor, an outdoor heat exchanger, an electronic expansion valve, an indoor heat exchanger, and an accumulator, each temperature detector disposed on the center and outlet pipes of the indoor heat exchanger, respectively; Temperature difference calculating means for calculating the degree of superheating of the indoor heat exchanger outlet gas from the signals from the respective temperature detectors, and determining the valve opening degree of the electronic expansion valve from the degree of superheating calculated by the means. and valve opening degree control means for controlling the electronic expansion valve to the determined valve opening degree, and by performing control by each means at predetermined time intervals, the compressor An air conditioner characterized by being configured to control the dryness of intake gas to a predetermined value.