JPH028231B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air conditioner in which a plurality of indoor units are connected to one outdoor unit, and particularly to control of a diaphragm device used to control a refrigeration cycle.

An example of an air conditioner for air conditioning multiple rooms is the one shown in FIG. 1 is an outdoor unit that includes a compressor 10, a heat source side heat exchanger 11, a blower fan 12, solenoid valves 13a, 13B, a throttle device 14A,
14B and diaphragm control devices 15A and 15B are housed therein. 2A and 2B are indoor units that house a heat exchanger 20 on the user side and a blower fan 21, respectively, and serve as input sources for the throttle device control devices 15A and 15B.
It has a first temperature sensor 22A provided at the intermediate portion of the usage-side heat exchanger 20, and a second temperature sensor 22B provided at the outlet of the usage-side heat exchanger 20. The throttle devices 14A and 14B include, for example, those that open and close valves using a motor, and those that have a valve drive unit that combines an electric heater and a bimetal.
5A controls the temperature difference SH' detected by the first and second temperature sensors 22A and 22B to a predetermined value. The electrical circuit of such an air conditioner is shown in FIG. 3A and 3B are the electric circuits of the indoor units 2A and 2B, respectively, and since they are the same in content, only the power switch 3A will be explained.
1, the motor 21M of the blower fan 21
is energized. 3A2 is a thermostat, and when thermostat 3A2 is turned on, outdoor unit 1 is turned on.
The relay 40A of the electric circuit 4 is turned on, and the control device 15A is energized, and the solenoid valve 13A is turned on, and the motor 12M for the compressor 10 and the blower fan 12 is turned on.
is energized. Relay 40B is indoor unit 2B
This is a relay for controlling the outdoor unit that corresponds to
is turned on and the motor 1 for the compressor 10 and the blower fan 12 is turned on.
2M is energized.

With the above configuration, when only relay 40A is on, all of the refrigerant flows into indoor unit 2A, and when both relays 40A and 40B are on, refrigerant flows into both indoor units 2A and 2B. indoor unit 2A when
Naturally, the refrigerant inflow amounts are different, and the inflow amount Q _c1 in the former case is larger than that Q _c2 in the latter case. Temperature difference with respect to change in unit throttling amount of throttling device 14A or 14B when refrigerant inflow is large
The amount of change △SH′ _H in SH _L is smaller than the amount of change △SH′ _L when the amount of refrigerant inflow is small. In other words, the process gain G _p of the refrigerant process formed by the expansion device and the utilization side heat exchanger changes. Also, the inlet/outlet pressure difference △P _H of the user-side heat exchanger when the refrigerant inflow is large is larger than the pressure difference △P _L when the refrigerant inflow is small, and therefore the inlet-outlet temperature difference △T of the user-side heat exchanger. is the temperature difference △T when the refrigerant inflow is large
The temperature difference ΔT _H when the refrigerant inflow is large is larger than the temperature difference ΔT _L when it is small. On the other hand, the temperature difference SH' has a relationship with the degree of superheating SH=SH=SH'+ΔT. Therefore, by keeping the temperature difference SH' at a predetermined value SH' _R within a range in which ΔT can be assumed to be constant, the degree of superheating SH can be kept at the optimum value SH _ppt for the refrigeration cycle. However, as described above, when ΔT changes, even if the temperature difference SH' is kept constant, the degree of superheating SH will not reach the optimum superheat SH _ppt for the refrigeration cycle.

As mentioned above, in conventional equipment, the superheat degree SH
cannot be kept at the optimal value SH _ppt . Also process gain
Since G _p changes, the response changes and an optimal response cannot be obtained. The present invention eliminates the drawbacks of the conventional device, constantly maintains the superheat degree SH at the optimum value SH _ppt , and furthermore, always obtains the optimum response, thereby always obtaining the optimum refrigeration cycle condition. As a result, an air conditioner with consistently highest EER was obtained.

FIG. 1 is an electrical circuit diagram of an outdoor unit according to an embodiment of the present invention. What is the electrical circuit in Figure 4? Relay 4
Control circuit 15 using 0A on/off signal as CA
B′, relay 40B on/off signal and CB
The difference is that the signal is input to the control circuit 15A' as a signal. If relay 40A is turned on and control device 15A' is operating, relay 40B
When turned on, this signal CB causes the control device 15 to
A′ is the predetermined temperature difference as its control parameter
SH′ _R and control gain G _c are automatically adjusted, and △T
and compensate for variations in process gain G _p .

FIG. 2 shows an embodiment of the above-mentioned control device 15A'. 15A'1 is the power supply circuit, DC voltage +
Outputs _Vcc and _-Vcc . Furthermore, power supply circuit 15A'1
is the relay A1 as control parameter changing means.
Built-in. 15A'2 is a control circuit, the first,
Difference in temperature SH' detected by thermistors 22A' and 22B' as second temperature sensors 22A and 22B =
The operational amplifier A7 amplifies the difference between T ₂ −T ₁ and a predetermined temperature difference SH′ _R given by the low resistor A2 or A3,
A voltage equal to its output voltage V _T is applied to the throttling device 14
A is applied to the thermoelectric expansion valve 14A'. The thermoelectric expansion valve 14A' has a valve driving section composed of a combination of an electric heater and a bimetal, and the applied voltage
V _T controls the valve opening degree, that is, the throttle amount. The operation of the control circuit 15A'2 controls the throttle amount of the thermoelectric expansion valve 14A', so that the temperature difference SH' becomes equal to the predetermined value _SH'L . Note that the control gain G _c is
It is given by G _c1 = R _A6 /R _A4 or G _c2 = R _A6 /R _A5 . However, R _A4 , R _A5 , and R _A6 are resistors A4 and A, respectively.
5, is the resistance value of A6. Relay 40B is currently off, and no refrigerant is flowing into indoor unit 2B.
When there is only one 2A indoor unit into which refrigerant is flowing, the amount of refrigerant flowing into indoor unit 2A is relatively large, so △T becomes large as △ _TH , and the process gain G _p becomes small as G _pH . It's summery. In this state, the predetermined temperature difference SH' _R is set to a small value SH' _RL , and the control gain G _c is set to a large value G _cH . relay 4
Since 0B is off, relay A1 is also off and the specified temperature difference
SH' _R is given by resistor A2. Therefore, each resistance value is determined so as to satisfy the relationship R _A2 <R _A3 so that the predetermined temperature difference SH' _R is smaller than SH _RL . Also, to increase the control gain G _c to G _cH , G _c1 > G _c2
That is, each resistance value is determined so as to satisfy the relationship R _A4 <R _A5 . When relay 40B is on and refrigerant is flowing into both indoor units 2A and 2B,
The amount of flow into indoor unit 2A becomes relatively small, △T becomes small (△T _L ), and the process gain
G _p becomes large as G _pL . At this time, since the relay A1 is turned on, the predetermined temperature difference SH' _R becomes large to SH' _RH , and the control gain G _c becomes small to G _cL .

In this way, by automatically changing the control parameters depending on the number of indoor units into which refrigerant flows, the degree of superheating SH can be kept constant, and an optimal response can always be obtained.

In the above explanation, the case where there are two indoor units has been described, but even when there are many more indoor units, for example, a relay having the same function as relay A1 may be added as appropriate, or resistors A2 and A3 may be installed.
This can be easily changed without departing from the spirit of the invention by increasing the number of resistors A4 and A5 accordingly. The present invention is intended to solve various problems caused by changes in the amount of refrigerant circulated, and the above explanation deals with the case where the number of indoor units in which refrigerant flows changes. The present invention can also be applied to cases where the capacitance changes, in which case it is necessary to change the control parameters as well. Therefore, as a method for detecting the amount of refrigerant circulation, it is sufficient to detect the number of indoor units into which refrigerant flows and the capacity of the compressor, and determine the control parameters based on a combination thereof.

FIG. 3 is a block diagram of a control device according to another embodiment of the present invention. 6 is a capacity control device that controls the capacity of a variable capacity compressor 10' in accordance with the output of the air conditioning state detector 6A. 15C is thermoelectric expansion valve 14
This is a control device that controls the aperture amount of A' and 14B'.
23A and 23B are temperature sensors corresponding to the temperature sensors 22A and 22B of the indoor unit 2B.
B1 is a relay that responds to relay 40B. 1
5C1 is an analog multiplexer that selects signals from temperature sensors 22A, B, 23A, and B based on the output of microcomputer 15C3, and 15C2
15C3 is an A/D converter that converts the signal selected by the analog multiplexer 15C1 into a digital quantity; 15C3 is the temperature sensor 22A, B, 23A,
The temperature difference SH' detected at B is expressed as that of indoor unit 2A.
While calculating SH′A and SH′B of 2B,
The number N of operating indoor units in which refrigerant enters is determined by the on/off states of relays A1 and B1, and furthermore, the number N of operating indoor units and the compressor capacity C _pp are determined by receiving a signal C pp corresponding to the current capacity from the capacity control device _6.
The predetermined temperature difference SH′ _R control gain G _c is determined by the built-in calculation program, and (SH′ _R −
SH′ _A ) and (SH′ _R −SH′ _B ) are calculated and each G _c
Output the result of multiplying by . 15C4 and 15C5 are DA converters that convert the calculation results output from the microcomputer 15C3 into analog quantities, and these output voltages V _TA and V _TB are applied to the thermoelectric expansion valve 14.
A' and 14B' are applied. If you do this,
The control parameters can be automatically adjusted by taking into account the compressor capacity _Cpp in addition to the number N of operating indoor units in which refrigerant flows.

As described in detail above, according to the present invention, changes in the refrigerant circulation amount are detected by taking into account the number of refrigerant inflow indoor units, and also the capacity when a variable capacity compressor is used, and thereby the control parameters are The superheat level SH is automatically adjusted, so the superheat level SH is always set to the optimal superheat level.
In addition to maintaining SH _ppt , the response as a control system can be optimized over the entire range, making it extremely
This has an excellent effect of making it possible to obtain an air conditioner with high EER.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of an outdoor unit of an air conditioner according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a control device for an air conditioner according to the present invention, and FIG. 3 is a diagram of another embodiment of the present invention. 4 is a refrigeration cycle diagram of an air conditioner, and FIG. 5 is a conventional electric circuit diagram. 1... Outdoor unit, 2A, 2B... Indoor unit, 14A, 14B... Throttle device, 15A', 15
B', 15C...control device, 15A'2...control circuit,
22A...second temperature sensor, 22B...first temperature sensor, A1...relay as parameter changing means.

Claims (1)

[Claims] 1 comprising one outdoor unit, a plurality of indoor units, a throttling device provided corresponding to each indoor unit, and a control device that controls the throttling amount of the throttling device according to the state of the refrigeration cycle, The control device includes a first temperature sensor provided at the inlet or intermediate portion of the heat exchanger of the indoor unit, a second temperature sensor provided at the outlet, and the temperature detected by the first and second temperature sensors. and a parameter changing means for changing the predetermined temperature difference and gain of the control circuit according to the number of operating indoor units. air conditioner.