JPH0223792B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an air-conditioning/heating hot water supply system in which a plurality of indoor units and a hot water storage tank for heating hot water supply water by heat pump operation are respectively connected to one outdoor unit mainly including a compressor. The present invention relates to a refrigeration cycle control device that controls an electric expansion valve in response to cooling/heating operation and heat pump hot water heating operation to achieve an optimal state of the refrigeration cycle.

Conventional configurations and their problems Conventionally, the method of optimizing the refrigeration cycle by controlling the degree of superheating of the refrigerant using an electric expansion valve was, for example, a separate air conditioner consisting of one indoor unit and one outdoor unit. Although it has already been put into practical use in , a system that has multiple indoor units to perform air conditioning and heating, as well as a hot water storage tank in addition to the indoor units, has the function of supplying and heating hot water by operating a heat pump. However, this has not been realized due to the difficulty of control or the complexity of the control device. In this type of heating, cooling, and hot water supply equipment,
Conventionally, there have been attempts to respond to load changes by controlling the amount of pressure reduction in two or three stages using electric expansion valves or capillary tubes, but this cannot be optimized at the end of the refrigeration cycle. There was a problem in making the system more efficient. In addition, in order to apply refrigerant superheat control using electric expansion valves to air conditioning, heating, and hot water heating operations, it is conceivable to install a separate control device for each electric expansion valve used, but this would result in a more complicated configuration and higher cost. For example, when changing from two-room cooling operation to one-room cooling operation, or from heating operation to heat pump hot water heating operation, the superheating characteristic changes suddenly due to a change in the refrigeration cycle. However, there were problems in terms of controllability, such as the difficulty of quickly returning the degree of superheat to a stable value.

Purpose of the Invention The present invention is an apparatus having a plurality of indoor units and a hot water storage tank for supplying and heating hot water by heat pump operation, in which the degree of superheating of a refrigerant is controlled using a plurality of electric expansion valves and one expansion valve control device. The objective is to constantly optimize the refrigeration cycle and achieve higher system efficiency than ever before, with the aim of stabilizing performance and simplifying and rationalizing the configuration of the control device. That is.

Structure of the Invention In order to achieve the above object, the present invention provides a compressor,
A hot water storage tank having a heat exchanger for heating hot water and a plurality of indoor units having indoor heat exchangers are connected to one outdoor unit consisting of a four-way valve, an outdoor heat exchanger, etc. a plurality of electric expansion valves for cooling, each of which reduces the pressure of refrigerant to the outdoor heat exchanger; an electric expansion valve for a heat pump, which reduces the pressure of the refrigerant to the outdoor heat exchanger; and an inlet portion or intermediate portion of the outdoor heat exchanger. a pair of temperature sensors that respectively detect the temperature of the outlet section of the outdoor heat exchanger or the suction section of the compressor; an expansion valve control circuit that inputs temperature signals from the respective temperature sensors and drives each of the electric expansion valves; an operation control circuit that controls the compressor, four-way valve, etc., and outputs an operation mode signal to the expansion valve control circuit that provides cooling, heating, hot water heating, and the number of cooling and heating rooms; When the compressor starts operating and when the operating mode signal changes, a predetermined electrical output signal corresponding to the operating mode signal is emitted to each of the electrical expansion valves for at least a certain period of time; The degree of superheating of the refrigeration cycle using the type expansion valve can be stably controlled in various operation modes, and the configuration of the entire system can be simplified and rationalized.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings. FIG. 1 shows a configuration diagram of an embodiment of a refrigeration cycle control device based on the present invention. In this example,
A case of an air-conditioning/heating-water supply device having a two-chamber air-conditioning/heating function and a hot water supply/heating function is shown. In FIG. 1, 1 is an outdoor unit, 2 is an indoor unit (here, for room A), 3 is an indoor unit (here, for room B), and 4 is a hot water storage tank. In the outdoor unit 1, 5 is a compressor, 6 is a four-way valve, 7h is an outdoor heat exchanger, and 8h is a blower for the outdoor heat exchanger 7h.
9a, 9b, 9h are unidirectional electric expansion valves (here, energized closed type thermoelectric expansion valves), 10a,
10b and 10h are check valves, 11a and 11, respectively.
b, 11w, 12a, 12b, and 12w are electromagnetic valves for opening and closing the refrigerant passages, respectively. 13h, 14
h, 14a, and 14b are equivalent temperature sensors (thermistors in this embodiment), which detect the temperature of the refrigerant. Reference numeral 15 denotes an expansion valve control circuit, which functions to drive the electric expansion valves 9a, 9b, and 9h and to control the degree of superheat of the refrigerant in the refrigeration cycle. 15m is an operation control circuit which controls the compressor 5, four-way valve 6, etc., and provides the expansion valve control circuit 15 with an operation mode signal indicating cooling, heating, hot water heating, and the number of cooling/heating rooms.

On the other hand, in indoor units 2 and 3, 7
a, 7b are indoor heat exchangers for air conditioning, 8a, 8b
is a blower, and 13a and 13b are temperature sensors (thermistors in this embodiment), and these temperature sensors 13a and 13b are equivalent to the temperature sensor 13h and the like. Further, in the hot water storage tank 4, 7w is a hot water heating heat exchanger for heating the hot water in the tank.

Next, the detailed configuration of the control circuit 15 will be explained with reference to FIG. In FIG. 2, reference numeral 16 inputs temperature signals from the temperature sensor 13a, etc., one set each,
For example, it is a temperature detection circuit that detects and outputs the temperature difference, ie, the degree of superheating SHa, etc. from the temperatures detected by the temperature sensors 13a and 14a. 17 is the superheat degree SHa, SHb, SHh from the temperature detection circuit 16 and the operation control circuit 1
This is an arithmetic processing circuit that inputs an operation mode signal (MODE) indicating cooling, heating, hot water heating, and the number of cooling/heating rooms given by the 5m, and determines the electrical output signal to be sent to the electric expansion valves 9a, 9b, and 9h. 18
Reference numerals a and 18b are drive circuits for driving the electric expansion valves 9a and 9b, respectively, and reference numeral 19 is a switching circuit for causing the drive circuit 18a to function as a drive circuit for the electric expansion valve 9h. This switching circuit 19 turns on and off a relay 20 in response to a signal from the arithmetic processing circuit 17, that is, a signal C/H depending on whether the cooling operation or heat pump operation is performed, and its contact 21 controls the output end of the drive circuit 18a. Connection is electric expansion valve 9a
and 9h.

In the arithmetic processing circuit 17, 22 is a microcomputer (microcomputer), 23 is a signal conversion circuit consisting of a DA converter, and 24 is an analog switch. A transfer circuit that performs time-division operation by switching based on signals Sa and Sb that are generated synchronously, 2
5a and 25b are signal holding circuits that temporarily hold the voltage transmitted from the transfer circuit 24. The signal holding circuits 25a and 25b are connected to the drive circuits 18a and 18b.
As a result, microcontroller 2
The digital signal D outputted by the control circuit 2 is converted and separated into an analog signal, and voltages Va and Vb are respectively issued from the two drive circuits 18a and 18b to the electric expansion valves 9a or 9h and 9b. In addition, Vcc
indicates the DC power supply voltage.

Next, the operation will be explained. In FIG. 1, solid line arrows indicate the flow of refrigerant during cooling operation, and broken line arrows indicate the flow of refrigerant during heating operation or hot water supply heating operation, that is, heat pump operation. However, during cooling operation, when there is only one room, for example, only room A, the solenoid valves 11b and 11w are closed. Further, during heat pump operation, for example, if only room B is heated, the solenoid valves 12a and 12w are closed, and
Solenoid valves 12a and 12b for hot water heating operation alone
is closed.

Next, the control operation of the electric expansion valves 9a, 9b, and 9h will be explained. During cooling operation, the degree of superheat is controlled independently depending on the operation of rooms A and B.
That is, the electric expansion valve 9a is driven by the drive circuit 18a so as to maintain the superheat degree SHa constant,
The electric expansion valve 9b is driven by the drive circuit 18b so as to maintain the degree of superheat SHb constant. When cooling only room B, the electric expansion valve 9a sets the applied voltage Va to zero or a low voltage to suppress power consumption and to ensure a refrigerant flow rate when cooling room A starts. . Further, since the contact 21 of the relay 20 is open, no power is applied to the electric expansion valve 9h.

During heat pump operation, contact 21 of relay 20
is on the electric expansion valve 9h side, the voltage of the electric expansion valve 9a for cooling room A is zero, and the applied voltage Vb of the electric expansion valve 9b for cooling room B is also zero. Electric expansion valve 9h for heat pump can heat 1 room and 2 rooms.
The degree of superheating SHh is controlled to be constant regardless of the operation modes such as room heating, hot water heating operation alone, and heating operation combined with heating operation, and the drive circuit 18a is also used for driving. At this time, the arithmetic processing circuit 17
The microcomputer 22 outputs a digital signal D corresponding to the electric expansion valves 9h and 9b by time-sharing operation instead of outputting to the electric expansion valve 9a during cooling operation. In this heat pump operation, heating 1
During indoor operation or single hot water heating operation, the refrigeration cycle is optimized by superheat degree control to achieve high efficiency operation, but when operating two room heating rooms or combined heating and hot water heating operation, the heat exchanger on each user side If there is an imbalance in the load on the indoor heat exchangers 7a, 7b or the hot water heating heat exchanger 7w,
The individual operating efficiencies of are not necessarily optimal.
However, as a whole of the apparatus, the superheat degree control of the refrigeration cycle functions stably, and practically good operating conditions can be obtained.

Next, when the compressor 5 is stopped, the electric expansion valves 9a, 9b, and 9h are not energized and are in an open state, and the electric expansion valves 9a, 9b, and 9h to be controlled are An electrical output signal is provided to the valve. The refrigeration cycle remains extremely unstable for a while after the compressor 5 is started, and the superheat characteristic changes in a complex manner regardless of the state of the electric expansion valve 9a, etc. The state changes according to the electrical output signal. Therefore, the expansion valve control circuit 15 controls the superheat level for at least a certain period of time (for example, 3 minutes) from the time when the compressor 5 is started.
It works to issue a constant electric output signal to the electric expansion valve 9a etc. regardless of SHa etc., and then to control the electric output signal according to the degree of superheating. Such an operation prevents the superheat degree characteristic from falling into an extremely large oscillation state, and as a result, the superheat degree SHa etc. can be stabilized at an early stage.

Furthermore, when the operation mode signal changes and the compressor 5 continues to operate, for example, the heating 2
When switching from indoor operation to single room heating operation, the superheat degree characteristics change rapidly and this state continues for a while. At this time, the electric expansion valve 9h is set to the superheat degree SHh.
When controlling according to the above, the superheat characteristic often falls into a state of large oscillation as described above. This occurs because the refrigeration cycle changes extremely slowly. Therefore, when the operation mode signal changes, an electric output signal of a predetermined value is issued to the electric expansion valve 9h for a certain period of time according to the operation mode signal after the change, and then it is controlled according to the superheat degree SHh. Stabilizes superheat control characteristics early.
In this case, the electric output signal before the operation mode signal changes is increased or decreased by a predetermined value when the operation mode signal changes, and after maintaining that state for a certain period of time, the control is performed according to the superheat degree SHh. Even if you do this, the same effect can be obtained.

In this way, by controlling the degree of superheating using the electric expansion valve 9a, etc. in FIGS. 1 and 2, it is possible to optimize and optimize the refrigeration cycle for each operating mode as early as possible. In terms of configuration, rational control is possible with one expansion valve control circuit 15, and cost reduction is achieved.

In the embodiments shown in FIGS. 1 and 2, the temperature sensors 13a and 13b can be installed inside the outdoor unit 1 depending on the intended use, and the temperature sensors 14a and 14b can be installed inside the indoor units 2 and 3.
Alternatively, the temperature sensor 14h may be provided between the four-way valve 6 and the outdoor heat exchanger 7h.

In addition to providing temperature sensors 13a, 14a, etc. as a set of two, corresponding to the indoor heat exchangers 7a, 7b, respectively, the temperature sensors 13a, 14a, etc. in FIG.
It is conceivable to omit a and 14b and use the temperature sensor 14h. In this case, as described in the above embodiment, the indoor heat exchangers 7a and 7b during cooling operation are
Although the superheating degrees SHa and SHb are not controlled independently of each other, they can be controlled relatively well and have the effect of further simplifying the configuration.

In addition, the number of air-conditioned rooms is not limited to two, and the same effect can be achieved even if there are more. In addition, outdoor unit 1
The compressor 5 may be an on-off type, but a continuously variable drive compressor such as a pole conversion type compressor or an inverter is easier to respond to changes in load, and the overall system configuration and performance are better. However, it can be said that the refrigeration cycle control device based on the present invention can sufficiently cope with this problem, and can even further demonstrate its functions.

Further, the electric expansion valves 9a, 9b, and 9h may be not only one-way type but also two-way type, and their configuration is not limited to thermoelectric expansion valves, but may be equivalent to electric expansion valves, for example.

Effects of the Invention As described above, the refrigeration cycle control device of the present invention simplifies and rationalizes the configuration of the control circuit and the entire system, and controls the degree of superheating of the refrigeration cycle with the electric expansion valve opened in various operation modes. It is possible to maintain the refrigeration cycle in an optimal manner, and is effective in improving the EER and SEER of the equipment.
Furthermore, since the state of the refrigeration cycle changes over a wide range in an air-conditioning/heating/water supply system that controls the capacity of the compressor, an extremely large effect can be expected in optimizing the refrigeration cycle.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a refrigeration cycle control device of the present invention, and FIG. 2 is a block diagram of a control circuit in the embodiment of FIG. 1. 1...Outdoor unit, 2, 3...Indoor unit, 4
...Hot water tank, 5...Compressor, 6...Four-way valve, 7a, 7b
...Indoor heat exchanger, 7h...Outdoor heat exchanger, 7w...Hot water heating heat exchanger, 9a, 9b...Electric expansion valve (for cooling), 9h...Electric expansion valve (for heat pump), 13a, 13b, 13h, 14a, 14b,
14h...Temperature sensor, 15...Expansion valve control circuit, 1
5m...Operation control circuit, 16...Temperature detection circuit, 17
...Arithmetic processing circuit, 18a, 18b...Drive circuit, 1
9...Switching circuit, 22...Microcomputer,
23... Signal conversion circuit, 24... Transfer circuit, 25a,
25b...Signal holding circuit.

Claims (1)

[Claims] 1. One outdoor unit consisting of a compressor, a four-way valve, an outdoor heat exchanger, etc., includes a hot water storage tank having a heat exchanger for heating hot water, and a plurality of indoor units having indoor heat exchangers. a plurality of electric expansion valves for air conditioning that reduce the pressure of each refrigerant to the indoor heat exchanger, and an electric expansion valve for a heat pump that reduces the pressure of the refrigerant to the outdoor heat exchanger; a pair of temperature sensors each detecting a temperature at an inlet portion or an intermediate portion of the outdoor heat exchanger and a temperature at an outlet portion of the outdoor heat exchanger or a suction portion of the compressor; The same number of pairs of temperature sensors as the number of pairs of temperature sensors as the number of indoor heat exchangers each detecting the temperature at the inlet or intermediate portion and the temperature at each outlet, and the temperature signals from each of the temperature sensors are inputted to each electric expansion unit. an expansion valve control circuit that drives the valve; and an operation control circuit that controls the compressor, four-way valve, etc., and outputs an operation mode signal that provides cooling, heating, hot water heating, and the number of cooling and heating rooms to the expansion valve control circuit. and the expansion valve control circuit applies a predetermined electrical output signal corresponding to the operation mode signal to each of the electric expansion valves for at least a certain period of time when the compressor starts operating and when the operation mode changes. A refrigeration cycle control device configured to emit light. 2. In the expansion valve control circuit, the predetermined electric output signal that is issued to each electric expansion valve for at least a certain period of time when the operation mode signal changes is set to a predetermined electric output signal that is generated after the change in the operation mode signal, regardless of the respective electric output signal before the change in the operation mode signal. Claim 1, characterized in that the predetermined value corresponds to the operation mode signal of
The refrigeration cycle control device described in Section 1. 2. In the expansion valve control circuit, the predetermined electrical output signal that is issued to each electric expansion valve for at least a certain period of time when the operating mode signal changes is a predetermined value that is a predetermined value from the value of each electrical output signal before the operating mode signal changes. The refrigeration cycle control device according to claim 1, characterized in that the value is increased or decreased.