Vehicular heat pump system and module therefor

Details Vehicular heat pump system and module therefor Vehicular heat pump system and module therefor

2002-05-07

2003-02-11

Tapolcai, William E. (Department: 3744)

Refrigeration

Disparate apparatus utilized as heat source or absorber

With vapor compression system

C062S324600

Reexamination Certificate

active

06516623

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to heat pump systems, particularly those intended for vehicular applications, and those utilizing a transcritical refrigerant such as CO
2
; and to a module useful in such systems.
BACKGROUND OF THE INVENTION
Refrigeration systems, such as air conditioning systems, have long been employed in vehicles, where they are highly desirable in terms of conditioning the environment in which an operator and/or passengers are seated. Such systems are not, however, without at least one draw-back. By their very nature, the many components are interconnected by fittings of various sorts which occasionally develop leaks. Furthermore, because the compressors in such systems are typically driven by an internal combustion engine that provides propulsion for the vehicle, the compressor and the drive therefor cannot be hermetically sealed in a single housing as is the case with residential or commercial refrigeration systems. In particular, because rotary power must be directed to the compressor, and such rotary power is typically mechanically derived from the engine of the vehicle, it is impossible to seal both the compressor and the engine in a single housing meaning that the moving components of the compressor must be sealed because they receive their motive force from an external device, i.e., the vehicle engine. Needless to say, these seals are capable of developing leaks and, in fact, refrigerant leaks from vehicular air conditioning systems are believed to be a major source of environmentally unfriendly compounds which damage the earth's ozone layer.
To overcome this problem, the industry first discarded the refrigerant commonly known as R12 in favor a more environmentally friendly refrigerant known as R134a. Even more recently, attention has focused on providing the desired air conditioning with refrigeration systems utilizing transcritical refrigerants that are even more environmentally friendly as, for example, carbon dioxide or CO
2
. CO
2
systems, for example, may be successfully utilized without concern for the net addition of environmentally harmful compounds to the atmosphere. The CO
2
to be used as a refrigerant is derived from the atmosphere by conventional means and utilized in such systems. Should such systems develop leaks, the CO
2
discharged simply returns to the atmosphere from which it was derived originally so there is no net gain in atmospheric CO
2
as a result of such leaks.
Notwithstanding, leaks in even CO
2
systems are highly undesirable because they necessitate periodic replenishment of the refrigerant used in the system. Replenishment is not without its costs in terms of both labor and material and consequently, it is desirable to minimize the leakage that occurs in such systems.
Furthermore, heat pump systems for use in both cooling and heating the interior of a vehicle provide some advantages. For example, they require only a single heat exchanger within the passenger compartment that is utilized for both heating and cooling whereas conventional systems require two such heat exchangers, one for evaporating a refrigerant to cool the passenger compartment and the other for rejecting heat to the passenger compartment from engine coolant. And, of course, both of these heat exchangers must be piped individually and provided with separate controls.
These additional components add to the cost of the vehicle and not infrequently add weight and bulk over and above that which would be present were a single heat exchanger and related piping to be employed for both heating and cooling. The additional weight adversely impacts on fuel economy making the vehicle more expensive to operate and requires the consumption of more fuel than would be the case if the weight of the vehicle could be reduced. This in turn can result in additional air pollutants being generated by engine operation which possibly could be reduced if the fuel economy could be improved. The additional bulk decreases the useful volume of the passenger compartment and typically makes servicing more difficult.
The present invention is directed to overcoming one or more of the above problems.
SUMMARY OF THE INVENTION
It is the principal object of the invention to provide a new and improved heat pump system. It is also an object of the invention to provide a module containing certain of the components of a heat pump system.
According to one facet of the invention, there is provided a heat pump system for use in a vehicle having a propulsion system that generates waste heat that is rejected to a coolant. The heat pump system includes a compressor, first and second heat exchangers with the first heat exchanger being adapted to be disposed in a passenger compartment or the like to alternatively reject or accept heat from the environment within the passenger compartment. The second heat exchanger is adapted to be disposed in a vehicle and located to be in an air stream that exists when the vehicle is in motion.
A module is hydraulically interposed between the compressor and the first and second heat exchangers. The module includes a base adapted to be mounted to a vehicle and an accumulator having an inlet and outlet is mounted on the base. A valving device is mounted on the base and includes an inlet fitting accessible from the exterior of the module connected to the high pressure side of the compressor. A valve outlet is connected to the accumulator inlet at a location within the module. A first inlet/outlet fitting accessible from the exterior of the module is connected from the valving device to the first heat exchanger and a second inlet/outlet fitting accessible from the exterior of the module is connected to the second heat exchanger. The valving device includes at least one valve member movable between positions to alternatively connect the inlet fitting to a selected one of the first and second inlet/outlet fittings and to alternatively connect the valve outlet to the other of the first and second inlet/outlet fittings. An expansion device is mounted on the base and has a first port provided with a fitting accessible from the exterior of the module and connected to the first heat exchanger. A heat exchanger component is also mounted on the base and has first and second heat exchange fluid flow paths. The first flow path is in heat exchange relation with the second flow path. The first flow path is connected to the accumulator outlet at a location within the module and also has an outlet fitting accessible from the exterior of the module and connected to a low pressure side of the compressor. The second flow path is connected to a second port on the expansion device at a location within the module and has an inlet/outlet fitting accessible exteriorly of the module and connected to the second heat exchanger. Transcritical refrigerant is in the heat pump system.
In a preferred embodiment, the valving device includes a single four-way valve.
In one embodiment, the heat pump system includes a closed housing having an interior space containing the base, the accumulator, the valving device, the expansion device and the heat exchanger component. The fittings are located on the exterior of the closed housing, and the accumulator inlet and outlet, the valve outlet and the expansion device second port are located within the closed housing interior space.
Even more preferably, the closed housing is insulated.
In a highly preferred embodiment of the invention, the heat exchanger component has first, second and third heat exchange fluid flow paths with the first flow path being in heat exchange relation with both the second and third flow paths. In this embodiment, the third flow path is adapted to be connected to a source of coolant.
In one embodiment, the heat exchanger component includes two separate heat exchangers within the module, both of the separate heat exchangers having a respective part of the first flow path and one of the separate heat exchangers has the second flow path and the other of the separate heat exchangers has the third flow path.
In another em

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