JPH0776643B2 - Two room air conditioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cooling and heating apparatus that has an electric expansion valve in a refrigeration cycle driven by an inverter compressor, and a refrigerant flow rate is controlled by the electric expansion valve. In particular, the present invention relates to one indoor unit and two outdoor units connected to an outdoor unit.

(Prior Art) Conventionally, a multi-room type air conditioner having two indoor units has an expansion valve corresponding to each indoor unit, and the expansion valve control controls the output of the compressor to stabilize the refrigeration cycle. I was only going to go. Therefore, the present inventors measure the stability of the refrigeration cycle, and to perform expansion valve control according to the load of each indoor unit, perform a refrigerant shunt test to each indoor unit, and the refrigerant flow rate obtained from the result. A two-chamber cooling and heating system in which the frequency of the compressor and the opening / closing degree of the expansion valve are related by the ideal characteristic diagrams (see Figs. 6 and 8) and the control characteristic diagrams (see Figs. 7 and 9) of did.

FIG. 1 is a diagram showing an outline of the overall configuration of a two-room cooling and heating device. In the figure, dotted arrows indicate the flow of the refrigerant during the cooling operation, and solid arrows indicate the flow of the refrigerant during the heating operation. That is, in the case of cooling, the refrigerant vapor compressed by the compressor 1 is condensed and liquefied by the outdoor heat exchanger 3 via the four-way valve 2 and stored in the receiver tanks 4a, 4b. After this, the refrigerant liquid is decompressed by the electric expansion valves 6a, 6b corresponding to the respective indoor units A, B, becomes low-pressure steam in the indoor heat exchangers 7, 8, merges in the branch pipe 18, and then again in four directions. Return to compressor 1 via valve 2. At this time, the frequency F of the compressor 1 and the electric expansion valves 6a for controlling the opening / closing degree of the electric expansion valves 6a, 6b according to the load of the indoor units A, B while stabilizing the refrigeration cycle are measured. The ratio of the switching degrees V _a and V _b of 6b is determined as follows.

That is, in the compressor frequency control unit 14 (see FIG. 2), which is a component of the microcomputer control unit 13, based on the relationship shown in Table 2, the set temperature in each room temperature setting device 12a, 12b and Difference from actual room temperature in room (TRa-TIa), (TRb-TIb)
Is regarded as the load in each room, and its range is defined by the load factors a, b.
Replace with. Then, as shown in Table 3, the frequency F of the compressor 1 is determined from the sum of the load coefficients.

On the other hand, in the expansion valve opening / closing control unit 15, the compressor frequency control unit 14
The signals of the load coefficients a and b of the indoor units A and B obtained in step 1 are received, and the ratio of the opening / closing degrees V _a and V _b of the electric expansion valves 6a and 6b is determined. In determining the ratio of the opening / closing degrees V _a , V _b of the electric expansion valves 6a, 6b, as shown in FIG. 6, the average of the outlet temperatures (TA), (TB) of the expansion valves 6a, 6b is determined. Temperature (TA + TB) / 2 and compressor 1
The ideal characteristic diagram of the refrigerant flow rate that keeps the degree of superheat obtained from the difference between the suction temperature (TS) and the constant temperature is obtained in advance. And
The relationship between the load coefficients a and b and the expansion valve opening / closing degrees V _a and V _b is determined based on this ideal characteristic diagram, and is determined based on the control characteristic diagram shown in FIG. 7 determined based on this relationship. 7. FIG. 7 is a control characteristic diagram created based on the ideal characteristic diagram shown in FIG.

In the case of heating, the refrigerant vapor compressed by the compressor 1 is
After branching through the branch pipe 18 via the four-way valve 2, each indoor unit A, B
It is condensed and liquefied in the indoor heat exchangers 7 and 8 of the receiver tank 4
Stored in a, 4b. After this, the refrigerant liquid is transferred to each indoor unit.
The pressure is reduced by the electric expansion valves 6a and 6b corresponding to A and B, evaporated in the outdoor heat exchanger 3, and again compressed through the four-way valve 2 into the compressor 1
Return to. At this time, the frequency F of the compressor 1 and the ratio of the opening / closing degrees c and d of the electric expansion valves 6a and 6b are determined in the same manner as in the case of cooling, but the refrigerant flow is in the opposite direction, so the refrigerant The ideal characteristic diagram of the flow rate is shown in FIG. 8 and the control characteristic diagram is shown in FIG.

As described above, in the conventional cycle, the ideal characteristic diagram is created by the refrigerant diversion test, and the frequency of the compressor and the opening / closing degree of the expansion valve are related by the control characteristic diagram based on this ideal characteristic diagram. .

(Problems to be Solved by the Invention) However, in this conventional expansion valve control method, it is necessary to carry out a refrigerant diversion test for creating an ideal characteristic diagram every time the size (rated capacity) of the indoor unit changes. Also, the control characteristic diagram based on this ideal characteristic diagram has a limit on the number of refrigerant diversion points and the set compressor frequency due to the restriction of the microcomputer capacity, so a staircase-shaped rough curve is plotted, especially the refrigerant diversion In the low compressor frequency range, which requires a large number of points, there were few refrigerant diversion points and control was poor.

The present invention has been made in view of the actual situation, and facilitates determination of the compressor frequency by using a mathematical expression that approximates the load relationship of each indoor unit shown in the control characteristic diagram to an ideal characteristic diagram, It is an object of the present invention to provide a two-room cooling / heating device in which a refrigerant distribution point to each indoor unit can be freely set and a different capacity indoor unit can be connected by changing parameters.

(Means for Solving the Problem) In the two-room cooling and heating apparatus of the present invention, one indoor unit is connected to two indoor units via electric expansion valves, and the refrigerant is compressed by a variable frequency compressor. Is condensed in each indoor heat exchanger or outdoor heat exchanger, the refrigerant is expanded and decompressed by each electric expansion valve, and then evaporated in the outdoor heat exchanger or each indoor heat exchanger to heat each room. Alternatively, in a cooling and heating device that performs cooling, the frequency F of the compressor is based on each indoor load obtained from the difference between the set temperature of the room temperature setting device installed in each indoor unit and the actual indoor temperature. The load coefficients are a and b, and the ratio of the indoor unit capacity of the load coefficient b to the indoor unit capacity of the load coefficient a is M, which is calculated from Equation (1) during cooling operation and from Equation (2) during heating operation. ^{, b = - {M 2 /} (f · F)} a 2 + · F ... (1) b = -M · a + f · F ... (2) where, f is the ratio V _b / V _a of the opening and closing of the proportionality constant above the electric expansion valve, each load factor a, b ratio It is determined by b / a.

(Operation) As shown by a dotted arrow in FIG. 1, when the two indoor units A and B are simultaneously operated for cooling, the refrigerant vapor compressed by the compressor 1 passes through the four-way valve 2 and the outdoor heat exchanger. Condensate and liquefy at 3. The refrigerant liquid thus obtained is stored in the two receiver tanks 4a and 4b. After this, the refrigerant liquid is decompressed by the electric expansion valves 6a, 6b corresponding to the indoor units A, B, becomes low-pressure steam in the indoor heat exchangers 7, 8, and again passes through the four-way valve 2 to the compressor 1 Return to.

At this time, as shown in FIG. 2, the compressor frequency control unit 14 of the microcomputer control unit 13 causes the set temperature (TIa) of the indoor unit A, the actually measured room temperature (TRa) of the room, and the set temperature of the indoor unit B to be set. (TI
b) and the measured room temperature (TRb) in the room are input. On the other hand, in the expansion valve opening / closing control unit 15, the temperatures (TA) and (TB) obtained from the temperature sensors 16a and 16b attached to the outlet pipes of the electric expansion valves 6a and 6b and the temperature attached to the suction pipe of the compressor 1 are obtained. The temperature (TS) obtained from the sensor 9 is input. Among these, in the compressor frequency control unit 14, the load coefficients a and b obtained from the indoor load (TRa-TIa) of the indoor unit A and the indoor load (TRb-TIb) of the indoor unit B are substituted into the equation (1). Then, the frequency of the compressor is calculated by this, the output of the compressor 1 is controlled, and the load coefficients a and b are output to the expansion valve opening / closing control unit 15. On the other hand, the expansion valve opening / closing control unit 15
Average of outlet temperature (TA) and (TB) of 6a and 6b (TA + TB) / 2
And the suction temperature (TS) of the compressor 1 keeps the refrigeration balance so that the degree of superheat obtained is constant, and each load coefficient a, b is equal to the load ratio b / a Expansion valve 6a, 6
and controlling the ratio V _b / V _a of the opening and closing degree of b, this cooling operation by is performed. Next, in the heating operation, as shown by the solid arrow in FIG. 1, the flow of the refrigerant vapor is in the opposite direction to that in the cooling operation, and the indoor heat exchangers 7 and 8 condense and liquefy, and the outdoor heat exchange. It becomes low-pressure steam in vessel 3. The functions of the other parts are the same as in the case of the cooling operation, except that the formula for determining the frequency of the compressor is formula (2).

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 6 shows an ideal control characteristic diagram of the refrigerant flow rate during cooling, which is obtained by a refrigerant distribution test of the indoor units A and B, and FIG. 8 shows an ideal control characteristic diagram of the refrigerant flow rate during the heating. Shows. This ideal control characteristic diagram is a mathematical expression in which the load coefficients a and b of the indoor unit A and the indoor unit B and the compressor frequency F are parameters, assuming a constant relationship between the refrigerant flow rate and the load coefficients a and b. Can be approximated by

That is, if the quadratic equation shown in the equation (3) is used as an approximate equation, b = −la ² −ma + n (3) However, l, m, n are constants. In the case of cooling, refer to FIG. It can be approximated by substituting m = 0 into the equation (3) (the equation (4)).

b = −la ² + n (4) Further, in the case of heating, referring to FIG.
It can be approximated by substituting 0 [Equation (5)].

b = -ma + n (5) The curves represented by the approximate expressions (4) and (5) are curves as shown in FIG. Here, equations (4) and (5) are the coordinates (a,
0) The values of points a and b of (0, b) are the capacity ratio (capacity ratio at the time of rating) M between the indoor unit A and the indoor unit B at the same frequency.
Can be approximated as [Equation (6)].

M = b / a (6) These points a and b are obtained by substituting (a, 0) (0, b) into the equation (4), which is an approximate equation during cooling,
It can be expressed by equations (7a) and (7b). And
By substituting the equations (7a) and (7b) into the equation (6) and replacing it with the equation l, the equation (8) is obtained.

In addition, in equation (5), which is an approximate equation for heating,
0) by substituting (0, b) for points a and b
Can be expressed by equations (9a) and (9b). Then, by substituting the expressions (9a) and (9b) into the expression (6) and replacing it with the expression m, the expression (10) is obtained.

a = n / m (9a) b = n (9b) m = M (10) Further, the intercepts (corresponding to n) of the equations (4) and (5) in FIG. As shown in the figure and FIG. 8, the frequency F of the compressor is changed as a parameter, and this relationship can be expressed as the equation (11). However, f
Indicates a constant of proportionality.

n = f · F (11) Then, by substituting the equations (8) and (11) into the equation (4), the load coefficients a and b and the compressor frequency F
Can be used as a mathematical expression [equation (1)] during cooling.

b = − {M ² / (f · F)} a ² + f · F (1) When this equation (1) is made into a curve, the ideal control characteristic diagram as shown in FIG. 4 is obtained, and the ideal control characteristic diagram of FIG. 6 is obtained. It can be seen that the characteristics are close to each other.

Further, by substituting the equations (10) and (11) into the equation (5), the equation [(2)] for heating with the load factors a and b and the compressor frequency F as parameters is obtained. You can

b = −M · a + f · F (2) When the equation (2) is made into a curve, an ideal control characteristic diagram as shown in FIG. 5 is obtained, and it may be approximated to the ideal characteristic diagram of FIG. Recognize.

Next, cooling / heating control using the mathematical expression [equation (1)] at the time of cooling and the mathematical expression [equation (2) at the time of heating will be described.

FIG. 1 is a circuit diagram showing an outline of the overall configuration of a two-room cooling and heating device.

As shown by the dotted arrow in the figure, in the case of cooling operation,
The refrigerant vapor compressed by the compressor 1 is condensed and liquefied by the outdoor heat exchanger 3 via the four-way valve 2, and the receiver tank 4
Guided by a and 4b. After that, the refrigerant is the electric expansion valve
After being decompressed by 6a, 6b, evaporated by the indoor heat exchangers 7, 8 of the indoor units A, B, and joined by the branch pipe 18, they return to the compressor 1 via the four-way valve 2 again.

At this time, the frequency of the compressor 1 and the opening / closing degrees V _a and V _b of the electric expansion valves 6a and 6b are determined as follows.

That is, as shown in FIGS. 1 and 2, each of the room temperature setting devices 12a, 12a,
The set temperatures (TIa) and (TIb) at 12b and the actually measured room temperatures (TRa) and (TRb) obtained from the indoor temperature sensors 11a and 11b are input, and the expansion valve opening / closing control unit 15 inputs the expansion valves 6a to the expansion valves 6a. Temperature (TA) and (TB) obtained from temperature sensors 16a and 16b attached to the outlet pipes of 6 and 6b, and temperature (TS) obtained from temperature sensor 9 attached to the suction pipe of compressor 1 are input. To be done.

Among these, in the compressor frequency control unit 14, based on the relationship as shown in Table 1, the difference (TRa-TIa) between the set temperature in each room temperature setting device 12a, 12b and the actually measured room temperature in each room (TRa-TIa), ( TRb-T
Ib) is regarded as the load in each room, and the range is taken as the load factor.
At the same time as substituting a and b for output to the expansion valve opening / closing control unit 15, this load coefficient is substituted into the equation (1) to determine the frequency F of the compressor 1.

On the other hand, in the expansion valve opening / closing control unit 15, the compressor frequency control unit 14
Load factor of each of the indoor units A, B obtained in a, receives a signal b, the electric expansion valve 6a by the load factor a, b figures, 6b of the opening and closing of V _a, and controls the V _b. That is, each of these electric expansion valves 6a, 6b
The open / close degrees V _a , V _b of the expansion valves 6a, 6b are the outlet temperatures (TA),
While keeping the superheat degree obtained from the difference between the average temperature (TA + TB) / 2 of (TB) and the suction temperature (TS) of the compressor 1 at a constant value,
Open / close ratio V _b / V _{a of} each electric expansion valve 6a, 6b and each load coefficient a, b
The ratio b / a is controlled to be the same, and the control is performed in consideration of a certain relationship between the initially assumed refrigerant flow rate and the load coefficients a and b.

Next, in the heating operation, as shown by a solid arrow in FIG. 1, the refrigerant vapor compressed by the compressor 1 is branched by the branch pipe 18 via the four-way valve 2 and then the indoor units A, B Are condensed and liquefied in the indoor heat exchangers 7 and 8 and guided to the receiver tanks 4a and 4b. After that, the refrigerant is decompressed by the electric expansion valves 6a and 6b, evaporated in the outdoor heat exchanger 3, and again the four-way valve 2
Return to compressor 1 via.

At this time, the ratio V _b / V _a of the frequency of the compressor 1 and the opening / closing degrees of the electric expansion valves 6a, 6b is determined in the same manner as during the cooling operation.

However, since the refrigerant flow is in the opposite direction, the load factors a, b
The mathematical expression for substituting is (2).

Next, a specific example of the control of the two-room cooling / heating apparatus using the mathematical formulas showing the ideal control characteristic diagrams as shown in FIGS. 4 and 5 having the same characteristics as those of the above-described embodiment will be described.

[First Specific Example] As shown in FIG. 4, when cooling, a = 14 and b = 14 at a compressor frequency F = 80 Hz, so n = 14 and M = 1. Also,
From equation (11), f = 0.175, and equation (1) becomes equation (1a).

b = − {(1 / (0.175 · F)} a ² + 0.175 · F (1a) For example, during cooling, the set temperature of the indoor unit A is TIa = 2.
7 ° C, the measured room temperature is TRa = 30 ° C, the set temperature of the indoor unit B is TIb = 27 ° C, and the measured room temperature is TRb = 32 ° C.
The load of the indoor unit A is (TRa-TIa) = 3, the load of the indoor unit B is (TRb-TIB) = 5, and the respective load coefficients a and b are shown in Table 1 as a = 5 for the indoor unit A and the indoor unit. B becomes b = 7. Substituting these load factors a and b into equation (1a), And the compressor frequency F = 55 Hz is obtained.

On the other hand, the opening / closing degrees V _a and V _b of the electric expansion valves 6a and 6b are V _b / V _a = 7/5
It is decided by the ratio of.

[Second Specific Example] As shown in FIG. 5, since a = 14 and b = 14 at the compressor frequency F = 80 Hz during heating, n = 14 and M = 1. Also,
From equation (11), f = 0.175, and equation (2) becomes equation (2a).

b = −a + 0.175 · F (2a) For example, during heating, the set temperature of the indoor unit A is TIa = 2
Assuming that the measured temperature is 1 ° C, the measured room temperature is TRa = 18 ° C, the set temperature of the indoor unit B is TIb = 21 ° C, and the measured room temperature is TRb = 16 ° C.
The load of the indoor unit A is (TRa-TIa) = 3, the load of the indoor unit B is (TRb-TIb) = 5, and the respective load coefficients a and b are shown in Table 1 for the indoor unit A as a = 5, the indoor unit B becomes b = 7. By substituting the load coefficients a and b into the equation (2a), 7 = -5 + 0.175 · F 12 = 0.175 · F F ≈69, and the compressor frequency F = 69 Hz is obtained.

On the other hand, the opening / closing degrees V _a and V _b of the electric expansion valves 6a and 6b are V _b / V _a = 7/5
It is decided by the ratio of.

(Effects of the Invention) As described above, according to the present invention, a memory map or the like is required in a microcomputer program by using a mathematical formula according to the load coefficient of the indoor unit in determining the compressor frequency. Instead, the compressor frequency can be finely set according to the load coefficient. In addition, connection with the indoor unit of different capacity can be easily performed by changing the variables of the mathematical expression, and comfortable cooling and heating can be performed.

[Brief description of drawings]

1 to 5 show the drawings of the present invention, FIG. 1 is a diagram showing the outline of the overall configuration of a two-room cooling and heating apparatus, FIG. 2 is a schematic block diagram of a microcomputer control unit, and FIG. FIG. 4 is a curve diagram showing the relationship between the load coefficient a of the indoor unit A and the load coefficient b of the indoor unit B, and FIG. 4 is a mathematical expression based on FIG. FIG. 5 is a curve diagram showing the relationship between the load coefficient b and the compressor frequency F, and FIG. 5 is a load coefficient a of the indoor unit A and a load coefficient b of the indoor unit B that are mathematically expressed based on FIG.
FIG. 6 is a curve diagram showing the relationship between the compressor frequency F and the compressor frequency F, and FIG. 6 is an ideal value of the refrigerant flow rate to each indoor unit at the frequency of the compressor during the cooling operation used in the conventional control and the expansion of each chamber corresponding thereto. FIG. 7 is a curve diagram showing the relationship between the valve opening / closing degrees, FIG. 7 is a curve view showing the relationship between the expansion valve opening / closing degree of each indoor unit created based on FIG. 6 and the corresponding load coefficient, and FIG. FIG. 9 is a curve diagram showing the relationship between the ideal value of the refrigerant flow rate to each indoor unit at the frequency of the compressor during the cooling operation used in the control of FIG. It is a curve figure which shows the relationship of the expansion valve opening / closing degree of each indoor unit produced based on it, and the load coefficient corresponding to it. 1 …… Compressor 3 …… Outdoor heat exchanger 4a, 4b …… Receiver tank 5 …… Heating expansion valve 6 …… Electric expansion valve 7,8 …… Indoor heat exchanger 9 …… Compressor suction pipe surface temperature Sensor 11a, 11b …… Indoor temperature sensor 12a, 12b …… Indoor temperature setter 13 …… Microcomputer control unit 14 …… Compressor frequency control unit 15 …… Expansion valve opening / closing control unit 16a, 16b …… Expansion valve outlet pipe surface Temperature sensor

Claims (1)

[Claims] 1. An outdoor unit is connected to two outdoor units via electric expansion valves, and a refrigerant compressed by a frequency variable compressor is used in each indoor heat exchanger or outdoor heat exchanger. In a cooling and heating device configured to condense, further expand and depressurize the refrigerant by each electric expansion valve, and then evaporate by the outdoor heat exchanger or each indoor heat exchanger to heat or cool each room, The frequency F of the compressor is a load coefficient based on each indoor load obtained from the difference between the set temperature of the room temperature setting device installed in each indoor unit and the actual indoor temperature, and the indoor unit of the load coefficient b Letting M be the ratio of the indoor unit capacity of the load coefficient a to the capacity, it is calculated from equation (1) during cooling operation and from equation (2) during heating operation, and b = − {M ² / (f · F)} ^{a 2 + f · F ... (} 1) b = -M · a + f · F ... ( ) Where, f is the ratio V _b / V _a of the opening and closing of the proportionality constant above the electric expansion valve, each load coefficients a, b of the ratio b / a two-chamber air conditioner characterized in that it is determined by.