AU2005100818A4 - Air Control System for an Air-Conditioning Installation - Google Patents

Description

P001 Section 29 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION INNOVATION PATENT Application Number: Lodged: Invention Title: Air Control System for an Air-Conditioning Installation The following statement is a full description of this invention, including the best method of performing it known to us: SAIR CONTROL SYSTEM FOR AN AIR-CONDITIONING INSTALLATION

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c FIELD OF THE INVENTION The invention relates to air-conditioning, heating and cooling systems and in particular to systems for controlling temperature and air-flow from an air- M 5 conditioning unit to multiple zones.

BACKGROUND OF THE INVENTION 0o 0Within the Australian domestic market, air-conditioning installations 00 Sgenerally comprise an air-conditioning unit, whose fan and compressor are controlled by a unit control system, and various collection and distribution C 10 apparatus.

N For an air conditioning installation within a house, air is generally drawn in to the air-conditioning unit via a return air grille which is located centrally within the house. Adjacent the return air grille of the unit will be located a temperature transducer from which will be received data relating to the "average" temperature within the house.

In a basic form, the air-conditioning unit may service two zones, and will be designed to have a capacity to provide sufficient air to the largest of these zones.

Thus the air-conditioning unit is limited in capacity to service one zone at a time.

Generally the zones are established on the basis of day and night cycles in that one zone may provide air for the bedrooms and the other zone to provide air to the day living spaces.

The unit is connected to each zone via connecting ducts which will have in series, an intermediate diverter and a terminal air diffuser located within the designated zone. So, in switching between one zone and another, it is a matter of opening the diverter of one zone and closing the other.

The problem with air-conditioning systems with multiple zones is the control of the air when some zones are blocked either manually by the user, or through a control system which may be as a result of temperature sensors. With existing systems it is necessary to ensure a sufficient air flow through the fan coil unit to prevent the evaporator coil freezing up or liquid refrigerant returning to the compressor and becoming inoperable.

In order to achieve this, the installation of the air-conditioning system will ensure that one duct remains open at all times. In this way even if the remaining 2 ducts for the various zones of the installation are shut down, air flow will continue eto flow through the remaining open duct. This will ensure air flow through the fan coil unit.

Clearly, such a system is not ideal, and therefore improvements to this Mr 5 arrangement would be beneficial.

SUMMARY OF THE INVENTION 00 oo With the above in mind the present invention provides in one aspect an air- 0conditioning system including: a distribution assembly for distributing air from a unit to at least one zone; a zone damper for each zone for controlling the flow of air to said zone; a temperature controller for controlling the position of the zone damper; a variable speed fan connected to a fan speed controller, the fan speed controller varying the speed of the fan in response to air static pressure sensed by an air static pressure sensor in a supply air duct of the distribution assembly; and a condensing unit with a digital scroll compressor connected to an unloading controller, the unloading controller unloading the compressor in response to refrigeration loads sensed by a supply air temperature sensor, said supply air temperature sensor providing an output used to maintain a predetermined supply air temperature during cooling and a different predetermined supply air temperature during heating.

BRIEF DESCRIPTION OF THE DRAWINGS It will be convenient to further describe the present invention with respect to the accompanying drawing which illustrate a possible arrangement of the invention. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawing is not to be understood as superseding the generality of the preceding description of the invention.

Figure 1 is a schematic view of an air-conditioning installation according to an embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to Figure 1 there can be seen an installation in accordance with an embodiment of the present invention. Figure 1 shows an air-conditioning installation which includes at least one air return grille 1, a variable speed fan 4, 3 motorised dampers 8, a plurality of distribution nodes 14, a plurality of Stemperature sensors 10, and a digital scroll compressor 11. These elements are all connected through a network of flexible ducting 3 and refrigerant pipes 9.

This arrangement does allow for the climate in multiple zones to be rr 5 individually controlled. The zone temperatures 10 can be linked to the motorised dampers 8 such that the dampers 8 are capable of shutting down any one of the 0_ distribution nodes 14 when any predetermined temperature is reached or if it is 00 not required to operate.

_The zone temperature sensors measure the actual zone temperature and C 10 compare it with a setpoint temperature. The associated damper motor can c modulate to achieve the setpoint temperature.

As zone dampers close, the system will require less air and less refrigeration capacity.

The air static pressure sensor 6 senses the air static pressure in the supply air duct 7 and compares the sensed air static pressure with the required setpoint.

The associated fan speed controller 5 will then increase or decrease the fan speed to achieve the required static pressure setpoint.

During a cooling mode, as the fan decreases in speed the refrigeration load will reduce and the supply air temperature will decrease. The supply air temperature sensor 15 senses the supply air temperature, for example, at the supply air duct in the refrigeration system and that temperature is compared with the predetermined setpoint.

The associated digital scroll unloading controller 13 will unload or load the compressor as required, depending on whether the condensing unit is in heating or cooling mode (i.e depending on the inverter sequence), in order to achieve the required supply air temperature setpoint. The predetermined setpoint can be different for the cooling mode than for the heating mode.

In summary as the heat load in a building decreases the dampers close and the fan capacity and refrigeration capacity are decreased accordingly to match the actual load in the building.

The present arrangement is unique in the preferred inclusion of two elements which have not previously been used in air-conditioning systems, namely the indoor fan control unit with an inverter to vary the speed of the evaporator fan 4 and the outdoor condensing unit 11 with digital scroll N compressor to vary the refrigeration capacity determined at least in part by the sensed supply air temperature. Neither of these two units have been used previously either individually or in combination in such a way.

S 5 As stated above the variable speed fan does allow the fan speed to be matched with the demands of the system. Previously some attempts have been 00 made to include a fan which has two or three speeds and is therefore capable of 00 Sstepping down or up from one step to another. However this does not allow the system to properly match the actual speed with the demands of the system. The invertor control variable speed fan of the present invention does allow the fan N speed to be controlled in direct proportion to the demands and is not limited to selecting only a single, two or three speeds and a bypass damper.

Similarly the inclusion of a condensing unit 11 with a digital scroll compressor is a development which allows for the refrigerant flow to be automatically distributed according to the load in each zone. The scroll compressor allows for intelligent energy distribution by instantly detecting and calculating the load in each unit and distributing the required flow to thus satisfy the energy demands for the entire system.

The compressor can be supplied with an external valve. This "Non- Closed" (de-energized) solenoid valve assists with modulation. When the solenoid valve is in its normally closed position the compressor operates at full capacity or in the "loaded state". When the solenoid valve is energized the two scroll elements move into the "unloaded state". During the unloaded state the compressor continues running, but since the scrolls are separated there is no compression. During the "loaded state" the compressor delivers 100% capacity and during the "unloaded state" the compressor delivers 0% capacity. Controlling the position of the valve thus enables capacity between 0-100% to be delivered.

"Loaded" or "unloaded" states, and intermediate positions in between 0% and 100% capacity, are determined from the sensed supply air temperature derived from the supply air temperature sensor 15. The output signal from the supply air temperature sensor is utilised by the digital scroll unloading controller 13 to control the digital scroll compressor of the condensing unit 11 to thereby maintain a predetermined supply air temperature during a cooling cycle and a different predetermined supply air temperature during heating. Further in the loaded state c or the unloaded state the digital scroll compressor has relatively low conversion a loss and further has a wide range of running capacity.

T. The present invention therefore provides a system which is more efficient c 5 than existing systems enabling a better control of the climate in multiple zones.

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