Patent Application
20060011337
This invention relates to heating and air-conditioning systems and, in particular, to combination heat pumps and air-conditioning systems.
Air-conditioning systems are conventionally installed in most vehicles, particularly in warmer climates. Usually the systems are only operational when the vehicle engine runs. However air-conditioning requirements may still exist when the engine is off. For example, it wastes a lot of fuel to maintain engine operation while the diesel vehicle is parked for a long period of time. However the operator of a tractor/trailer unit may require air-conditioning for the cab while he or she is resting. For this reason many diesel powered highway vehicles are equipped with auxiliary power units. These include a diesel engine which is relatively small compared with the main engine of the vehicle. Each auxiliary power unit (APU) conventionally includes a generator or alternator connected to the engine thereof. This provides electrical power to the vehicle while the main vehicle engine is off. The electrical power from the APU can be used to power an air-conditioner to maintain cooling of the cab while the vehicle is parked.
However, the vehicle may also require heating for the cab while the vehicle is parked. Theoretically this could be done by circulating liquid coolant from the APU engine through a heat exchanger in the cab. However this requires additional plumbing in the cab and it may be difficult to find space available for another heat exchanger. Also the engine of the APU may only provide sufficient heat if the engine is operating under a load. If no such load otherwise occurs, then it may be necessary to apply a load to the engine merely for purposes of generating sufficient heat. Obviously this wastes fuel.
An engine outputs energy in three different ways. Roughly one third of the energy goes to the mechanical, rotational output of the engine, which can be used for such purposes as running the APU generator. Another one third of the energy goes to exhaust. A final third is transferred to the engine coolant. Only this last third would normally be available for heating the cab of the vehicle.
Heat pumps have been used in the past to heat buildings and require a source of heat, for example heat obtained from the ground. Heat pumps are capable of transferring heat from a lower temperature body, such as the ground, to a higher temperature body, such as the interior of a building. This is done by applying energy, using a compressor, to compress a heat transfer medium such as a glycol/water mixture. Subsequently the heat transfer medium passes through a condenser where the medium is condensed by exchanging heat with the ambient air circulated through the condenser by a fan. Thus, the air in the building is heated. The liquefied heat transfer medium then passes through an expansion valve and flows through an evaporator where thermal energy is applied, by heat from the ground in the case of a conventional building-installed heat pump. The heated medium is then drawn into the compressor where it is compressed and the cycle continues.
Heat pumps have not been used traditionally in vehicles, in part because there is no obvious source of heat. Clearly vehicles move and accordingly connections to the ground are not possible.
According to one aspect of the invention, there is provided a combined heat pump and air-conditioning apparatus. There is a source of heat, a compressor having an input and an output, a heat exchanger, a condenser, an evaporator and first conduits for connecting the source of heat to the evaporator. There are heat transfer medium conduits interconnecting the heat exchanger, the condenser and the evaporator. A valve is operatively connected to the medium conduits and connects the output of the compressor to the condenser and connects the heat exchanger to the input of the compressor during an air-conditioning mode where the heat exchanger operates as an evaporator. The valve operatively connects the output of the compressor to the heat exchanger and connects the input of the compressor to the evaporator during a heat pump mode where the heat exchanger acts as a condenser.
According to another aspect of the invention, a combined heat pump and air-conditioning apparatus comprises a heat exchanger, a condenser, an evaporator, an internal combustion engine, and a compressor operatively connected to the engine. The compressor has an input port and an output port. There is also a valve, a first conduit connected to the output port of the compressor, a second conduit connected to the heat exchanger, a third conduit connected to the heat exchanger, a fourth conduit connecting the third conduit to the evaporator, a fifth conduit connected to the evaporator, a sixth conduit connected to the condenser, a seventh conduit connected to the input port of the compressor, an eighth conduit connected to the sixth conduit and the fifth conduit and a ninth conduit connected to the condenser and to the third conduit. Coolant conduits connect the engine to the evaporator for supplying heated engine coolant to the evaporator. There is a valve having a first port, a second port, a third port, a fourth port and a movable valve member for interconnecting the ports, the first port being connected to the seventh conduit, the second port being connected to the second conduit, the third port being connected to the first conduit and the fourth port being connected to the eighth conduit. The apparatus has an air-conditioning mode where the valve member connects the second port to the first port and connects the third port to the fourth port, whereby a heat transfer medium compressed by the compressor flows to the condenser through the first conduit, the eighth conduit and the sixth conduit. The heat transfer medium flows from the condenser to the heat exchanger through the ninth conduit and the third conduit and flows from the heat exchanger to the input port of the compressor through the second conduit and the seventh conduit. The apparatus has a heat pump mode where the valve member connects the third port to the second port and the fourth port to the first port, whereby the heat transfer medium compressed by the compressor flows to the heat exchanger through the first conduit and the second conduit, and flows from the heat exchanger to the evaporator through the third conduit and the fourth conduit. The heat transfer medium flows from the evaporator to the input port of the compressor through the fifth conduit, the eighth conduit and the seventh conduit.
According to a further aspect of the invention, there is provided a vehicle having an interior, an internal combustion engine and a combined heat pump and air-conditioning apparatus. The apparatus has a compressor with an input and an output, a heat exchanger communicating with the interior of the vehicle, a condenser, an evaporator and heat transfer medium conduits for a heat transfer medium. The medium conduits interconnect the heat exchanger, the condenser and the evaporator. Coolant conduits interconnect the evaporator and the engine for carrying coolant heated by the engine. A valve is operatively connected to the medium conduits and connects the output of the compressor to the condenser and connects the heat exchanger to the input of the compressor during an air-conditioning mode where the heat exchanger operates as an evaporator. The valve operatively connects the output of the compressor to the heat exchanger and connects the input of the compressor to the evaporator during a heat pump mode where the heat exchanger acts as a condenser.
According to a still further aspect of the invention, there is provided a method of heating and cooling a space having a heat exchanger and a fan for directing air over the heat exchanger into the space. The method comprises cooling the space during an air-conditioning mode by connecting an output of a heat transfer medium compressor to a condenser, connecting the condenser to the heat exchanger and connecting the heat exchanger to an input of the compressor, whereby the heat exchanger and fan act as an evaporator for cooling the space. The space is heated during a heat pump mode by connecting the output of the compressor to the heat exchanger, connecting the heat exchanger to an evaporator and connecting the evaporator to the input of the compressor.
Referring to the drawings, these show a combined heat pump and air-conditioning apparatus 10 according to an embodiment of the invention. The apparatus includes a heat exchanger 12 which, as detailed below, acts alternatively as an evaporator or condenser depending upon the mode of operation of the apparatus. Air driven past the heat exchanger 12 by a fan 16, adjacent to the heat exchanger, is discharged into interior 20 of cab 22 of a vehicle. The heat exchanger in this particular example may be a conventional or pre-existing heat exchanger and fan which normally function as an evaporator for an air-conditioning system powered by an auxiliary power unit for the vehicle. In one particular embodiment the heat exchanger may comprise a second coil in a pre-existing evaporator installed in the vehicle for the conventional air-conditioning system powered by the vehicle engine, as disclosed in the co-pending patent application entitled AUXILIARY AIR-CONDITIONING APPARATUSES AND METHODS FOR VEHICLES and assigned to Teleflex Canada Incorporated.
The apparatus also includes an air-conditioning condenser 24 with a fan 25, a heat pump evaporator 26 and a compressor 28 driven by engine 30 which, in this example, is an auxiliary engine for the vehicle forming part of an auxiliary power unit for the vehicle. The evaporator heats a heat transfer medium flowing through conduits 54 and 55 with engine coolant flowing through coolant conduits 96 and 98. In this example a continuous belt 32 operatively connects sheave 34 of the engine, shown in
There is a first conduit 51 connected to output port 60 of the compressor, a second conduit 52 connected to a first port 62 of the heat exchanger, a third conduit 53 connected to port 64 of the heat exchanger and a fifth conduit 55 connected to port 68 of the evaporator. There are a sixth conduit 56, a seventh conduit 57 and an eighth conduit 58. Conduit 56 connects port 66 of the condenser to the fifth conduit 55 and to the eighth conduit 58. The seventh conduit 57 is connected to input port 70 of the compressor.
The valve 40 has four ports 81, 82, 83 and 84. Port 81 is connected to the seventh conduit 57. Port 82 is connected to second conduit 52. Third port 83 is connected to conduit 51, while fourth port 84 is connected to eighth conduit 58.
The valve has a valve member or spool 90 which is movable to two different positions, shown in
The coolant conduits 96 and 98 extend from the engine 30 to the evaporator 26 for providing hot coolant from the engine to the evaporator and for returning the coolant to the engine.
There is a first one-way valve 100 positioned along ninth conduit 59 which prevents a flow of fluid toward the condenser 24. A second one-way valve 102 is located along fifth conduit 55 and prevents a flow of fluid toward the evaporator 26.
During the air-conditioning mode, as shown in
Referring to
It will be understood by someone skilled in the art that many of the details provided above are by way of example only and can be varied or deleted without departing from the scope of the invention which is to be interpreted with reference to the following claims.
