US20080264088A1

US20080264088A1 - Reversible mode vehicle heating and cooling system for vehicles and method therefor

Info

Publication number: US20080264088A1
Application number: US12/148,988
Authority: US
Inventors: Arthur E. Hirsch; Marion J. Hoard
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-04-24
Filing date: 2008-04-24
Publication date: 2008-10-30

Abstract

A reversible mode heating and cooling system for an interior space of a vehicle having an Auxiliary Power Unit (APU) employs a heat pump arrangement, wherein a refrigerant compressor is driven by APU's diesel engine through pulley and belt arrangement. An air duct is provided to communicate engine exhaust air to an external heat exchanger during a heating mode. Openings and dampers are provided in the air duct to direct engine exhaust air flow to atmosphere and introduce ambient air into the external heat exchanger during cooling mode. Exhausted air from the external heat exchanger may be re-circulated back to the air inlet side of the engine. Provisions are also provided for operating the refrigerant compressor from the electrical power grid.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and claims priority from Provisional Patent Application Ser. No. 60/926,153 filed on Apr. 24, 2007.

FIELD OF THE INVENTION

The present invention relates, in general, to heating and cooling systems and, more particularly, this invention relates to a reversible mode heating and cooling system for an interior space that employs a heat pump arrangement directly driven by a diesel engine of the Auxiliary Power Unit (APU).

BACKGROUND OF THE INVENTION

As is generally well known, the anti-idling laws that prohibit over-the-road truck drivers from running their truck engines while stationary have combined with higher fuel prices to create a high level of interest in Auxiliary Power Units (APU's) for over-the-road long-haul trucks. These APU's are small power plants that are attached to the truck frame and utilize one, two or three cylinder diesel engines often in the nine to fourteen horsepower range. The APU's provide heat, air conditioning and electrical power to the trucks when they are parked without the necessity of running the main truck diesel engine. An in-bunk unit in the cab uses air conditioning technology to provide cooling and electrical resistance heating elements to provide heat when needed. Unused electrical capacity is available to power standard one hundred ten volt residential type appliances such as refrigerator, lighting, microwave, etc.
Prior to the conception and development of the present invention, an engine-turned electrical generator has been employed with the APU to provide four to six kilowatts (KW) of one hundred ten volt alternating current (AC) electrical power.
U.S. Pat. No. 7,152,421 issued to Parks et al. discloses one type of such system that also incorporates a heat pump operating conventionally with air drawn from outside the system through its condenser coils and removing heat to the exterior for cooling. In the heating cycle, the condenser motor blower stops and reverses rotation. Outside air is drawn in by the condenser fan, is circulated across the diesel engine and generator, and is blown through the condenser coils outside of the unit. This system can be installed within a truck, bus, boat, cabin, camper, and the like. While this system adequately cools and heats cab compartment, use of the electrical generator increases installation and maintenance costs as well as decreases overall efficiency of the system by first converting the mechanical energy of the diesel engine into the electric energy at the generator and then converting the generated electrical energy into mechanical energy driving the refrigerant compressor for enabling heating or cooling modes.
Therefore, there is a need for a cost effective and energy efficient system employing a heat pump technology and operable in combination with APU for heating and cooling an interior space.

SUMMARY OF THE INVENTION

The invention provides a novel reversible mode heating and cooling system for heating and cooling an interior space of a vehicle including an air cooled diesel engine and an engine fan connected to a shaft thereof and further including a heat exchange unit mounted within an interior space of the vehicle and arranged in heat exchange relationship with air in the interior space for condensing a refrigerant and heating the air during the heating mode and evaporating the refrigerant and cooling the air during the cooling mode.
In accordance with aspect, the invention provides a compressor for compressing vaporous refrigerant. The compressor is arranged in refrigerant communication with the interior heat exchange unit. A power transmission means is provided for connecting the compressor to a rotating shaft of the diesel engine and for operating the compressor thereby. A heat exchanger is mounted externally in heat exchange relationship with each of the ambient air and exhaust air from the engine. The heat exchanger is further arranged in refrigerant communication with the compressor for evaporating refrigerant during the heating mode and condensing the refrigerant during the cooling mode. A blower unit is provided in air communication relationship with the heat exchanger. A refrigerant expansion valve is operatively disposed intermediate the heat exchanger and the heat exchange unit. Finally, a refrigerant flow reversing valve is operable for providing heating and cooling modes from the system by a refrigerant flow direction selection.
In accordance with another aspect, the invention provides a compressor for compressing vaporous refrigerant. The compressor is arranged in refrigerant communication with the interior heat exchange unit. A heat exchanger is mounted externally in heat exchange relationship with each of the ambient air and exhaust air from the engine. The heat exchanger is further arranged in refrigerant communication with the compressor for evaporating refrigerant during the heating mode and condensing the refrigerant during the cooling mode. An air duct means is provided in air communication with each of the engine fan and the heat exchanger for supplying air thereto. A blower unit is disposed in air communication relationship with the heat exchanger. A refrigerant expansion valve is operatively disposed intermediate the heat exchanger and the heat exchange unit. A refrigerant flow reversing valve is operable for providing heating and cooling modes from the system by a refrigerant flow direction selection.
According with a further aspect of the invention, there is provided a compressor for compressing vaporous refrigerant. A power transmission means connects the compressor to a rotating shaft of the diesel engine for operating the compressor thereby. A first heat exchanger is mounted externally in heat exchange relationship with exhaust air from the engine, the first heat exchanger further arranged in refrigerant communication with the compressor for evaporating refrigerant during the heating mode. A second heat exchanger is also mounted externally in heat exchange relationship with the ambient air, the second heat exchanger further arranged in refrigerant communication with the compressor for condensing the refrigerant during the cooling mode. A blower unit is disposed in air communication relationship with the second heat exchanger. A pair of refrigerant expansion valve are provided. The first refrigerant expansion valve is operatively disposed intermediate the first heat exchanger and the internal heat exchange unit. The second refrigerant expansion valve is operatively disposed intermediate the second heat exchanger and the internal heat exchange unit. A refrigerant flow reversing valve is operable for providing heating and cooling modes from the system by a refrigerant flow direction selection. A first check valve is operatively disposed intermediate the refrigerant flow reversing valve and the first heat exchanger for preventing refrigerant flow thereto during the cooling mode. A second check valve operatively disposed intermediate the second heat exchanger and the internal heat exchange unit for preventing refrigerant flow to the second heat exchanger during the heating mode.
In accordance with another aspect of the invention, there is provided a method for at least one of heating and cooling an interior space of a vehicle including an auxiliary power unit having an engine and an engine fan connected to a shaft thereof. The method includes the step of providing a heat pump apparatus having a refrigerant compressor. Connecting the refrigerant compressor to the shaft of the engine with a power transmission means. Then, selectively cooling and heating the interior space with the heat pump apparatus.

OBJECTS OF THE INVENTION

It is, therefore, one of the primary objects of the present invention to provide a reversible mode heating and cooling system for an interior space that employs a heat pump technology.
Another object of the present invention is to provide a heat pump based heating and cooling system wherein the refrigerant compressor is powered directly by the diesel engine of the APU.
Yet another object of the present invention is to provide a heat pump based heating and cooling system that employs a pair of movable flaps for controlling air flow during heating and cooling modes.
A further object of the present invention is to provide a heat pump based heating and cooling system that meets present cooling and heating requirements even though such system is less expensive to manufacture.
An additional object of the present invention is to provide a heat pump based heating and cooling system that can operate from electrical power grid.
In addition to the several objects and advantages of the present invention which have been described with some degree of specificity above, various other objects and advantages of the invention will become more readily apparent to those persons who are skilled in the relevant art, particularly, when such description is taken in conjunction with the attached drawing Figures and with the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side schematic view of a long-hole truck with a reversible mode cooling and heating system of the present invention;

FIG. 2 is an air flow schematic diagram illustrating a cooling mode operation of a reversible mode cooling and heating system of the present invention constructed in accordance with a presently preferred embodiment of the invention;

FIG. 3 is a refrigerant flow schematic diagram illustrating cooling mode operation of the reversible mode cooling and heating system of FIG. 2;

FIG. 4 is an air flow diagram illustrating heating mode operation of the reversible mode cooling and heating system of FIG. 2;

FIG. 5 is a refrigerant flow diagram illustrating heating mode operation of the reversible mode cooling and heating system of FIG. 2;

FIG. 6 is an air flow diagram illustrating operation of the reversible mode cooling and heating system constructed in accordance with an alternative embodiment of the present invention;

FIG. 7 is a refrigerant flow diagram illustrating operation of the reversible mode cooling and heating system of FIG. 6; and

FIG. 8 is a schematic block diagram of the reversible mode cooling and heating system of the present invention, particularly illustrating an optional apparatus for operating the refrigerant compressor from an electrical power grid.

BRIEF DESCRIPTION OF THE VARIOUS EMBODIMENTS OF THE INVENTION

Prior to proceeding to the more detailed description of the present invention, it should be noted that, for the sake of clarity and understanding, identical components which have identical functions have been identified with identical reference numerals throughout the several views illustrated in the drawing figures.
It is to be understood that the definition of an interior space applies nut is not limited to an interior compartment for truck, bus, boat, cabin, camper, and the like vehicles and structures.
The best mode for carrying out the invention is presented in terms of its presently preferred and alternative embodiment, herein depicted within FIGS. 1 through 8. However, the invention is not limited to the described embodiments, and a person skilled in the art will appreciate that many other embodiments of the invention are possible without deviating from the basic concept of the invention and that any such work around will also fall under scope of this invention. It is envisioned that other styles and configurations of the present invention can be easily incorporated into the teachings of the present invention, and only several particular configurations shall be shown and described for purposes of clarity and disclosure and not by way of limitation of scope.
The heating and cooling system of the present invention is shown and described in combination with an Auxiliary Power Unit (APU) employed on over-the-road long-haul truck, although it will be apparent to those skilled in the art that the heating and cooling system of the present invention may be employed for heating other interior spaces.
Reference is now made to FIG. 1 that depicts an environment wherein a reversible mode heating and cooling system, generally designated as 20, of the present invention is employed. Particularly shown is a long-haul truck 2. The truck 2 includes a cab 4 to which a sleeper cabin 6 may be connected. The cab 4 and the sleeper cabin 6 (when provided) define the interior space to be cooled or heated by the system 20 of the present invention. The auxiliary power unit (APU) system 10 is also provided and is generally mounted on the side of a frame 8 of the truck 2.
The APU 10 can be any conventional APU presently in use and, thus, the detail description of such APU 10 will be omitted for the sake of brevity. The elements of the APU 10 that have importance to the operation of the system 20 are an engine 12 and an engine fan 16 mounted within the housing 18 and provided for cooling the engine 12 with air.
Preferably, the engine 12 is of one cylinder an air-cooled diesel type, such as a Yanmar LV 100 or equivalent which is advantageous for its low power consumption and employment of a small, about one hundred seventy five watt electrical generator.
Now in reference to FIGS. 2-5, there is shown the reversible mode heating and cooling system 20 which is constructed in accordance with a presently preferred embodiment of the invention.
The system 20 includes a compressor 22 for compressing vaporous refrigerant, such as a Freon. There is also a power transmission means that is provided for connecting the compressor 22 to a rotating shaft 14 of the diesel engine 12 so that the compressor 22 can be operated directly by the engine 12.
A first heat exchanger 30 is externally mounted and is arranged in a heat exchange relationship with outdoor ambient air and in refrigerant communication with the compressor 22 for evaporating refrigerant during the heating mode and condensing the refrigerant during the cooling mode. As is conventional, the first heat exchanger includes a coil 32. A blower unit 34 is provided in air communication relationship with the first heat exchanger 30. The blower unit 34 has a fan 36 which is preferably electrically operable.
An air duct 40 is provided in air communication with the engine fan 14 and the first heat exchanger 30 for supplying air thereto.
There is also a conventional heat exchange unit 50 which is arranged in heat exchange relationship with air in the interior space for condensing refrigerant and heating the air and in refrigerant communication with the compressor 30 during the heating mode and evaporating refrigerant and cooling the air during the cooling mode. The second heat exchanger 50 is generally referred to as “in-bunk” unit and is mounted internal to the interior space to be cooled or heated. As is conventional, a bi-directional refrigerant expansion valve 60 is operatively disposed intermediate the first and second heat exchangers 30, 50 to maintain the pressure drop in the refrigerant and control the refrigerant flow. Any existing residential or automotive expansion valves may be employed in the present invention.
A refrigerant flow reversing valve 62 is also provided and is operable for providing heating and cooling modes from the system 20 by a refrigerant flow direction selection.
The presently preferred power transmission means, best illustrated in FIG. 4, includes a belt member 24 and a pair of pulleys 26, 28. One of the pair of pulleys, referenced with numeral 26, is secured to the rotating shaft 14 of the engine 12 for rotation therewith. The other pulley, referenced with numeral 28 is rotatably secured to the shaft 23 of the compressor 22.
In operation, during the cooling mode of FIGS. 2 and 3, the compressor 22 pumps the refrigerant to the reversing valve 62. The reversing valve 62 directs the flow to the first heat exchanger 30 which functions as a condenser where the fan 34 cools and condenses the refrigerant to liquid. The air flowing across the first heat exchanger coil 32 from the engine 12 through the air duct member 40 removes heat from the refrigerant. The liquid refrigerant then flows to the second heat exchanger 50 which functions as an evaporator. There it picks up heat energy from the air blowing across the coil of the second heat exchanger 50 and the air comes out cooler for cooling the interior space. The resulting refrigerant vapor then travels back to the reversing valve 62 to be directed to the compressor 22 to start the cycle all over again.
During the heating mode of FIGS. 4 and 5, the reversing valve 62 directs the compressed refrigerant to the second heat exchanger 50 first. This makes the second heat exchanger 50 function as the condenser and releases the heat energy. This heated air is then communicated into the interior space. The first heat exchanger 30 then functions as evaporator and collects the heat energy. As has been described above, the first heat exchanger 30 is in direct communication with the waste heat released during cooling of the engine 12. This arrangement facilitates the use of the engine cooling air (waste heat) to heat the first heat exchanger 30 during the heating mode. This provides two advantages. First, the system 20 consumes less energy and second, the system 20 operates efficiently even when the ambient temperature drops below 23 degrees Fahrenheit due to the higher temperature of the air entering the first heat exchanger 30. This is a significant improvement over the prior art cooling and heating systems, for example where the colder ambient air may be drawn into the heat exchanger.
Furthermore, during the heating mode, operation of the fan 36 is not necessary. Thus, the system may be adapted with ON/OFF controls, such as switch 38, for selectively operating the fan 36 which, in this arrangement, is not required during the heating mode.
While the above described system 20 is capable of cooling and heating the interior space, it has been found that adapting the duct means 40 with a pair of openings and a pair of dampers or flaps, which are operable to selectively cover and uncover the openings, improve the efficiency of the system 20 particularly in the heating mode when the ambient air is below about twenty three degrees on the Fahrenheit scale.
Accordingly, a first opening 70 is provided for exhausting air from the engine fan 14 to atmosphere and is equipped with a first damper or flap 74 which is movable for covering the first opening 70 during heating mode and opening the first opening 70 during the cooling mode. The first damper or flap 74 may be of a conventional type, for example rotatably mounted within the air duct 40 with a shaft 73. A second opening 72, which may be a pair of openings 72, is provided for enabling flow of ambient air into the first heat exchanger 30 and is equipped with a second damper or flap 76 for covering the second opening(s) 72 during heating mode and uncovering the second opening(s) 72 during cooling mode. Each damper or flap may be manually operated however it is presently preferred to provide a powered actuator, for example such as an electric motor 78 for operating such each damper or flap.
During the heating mode, the openings 72 and 74 are covered facilitating flow of the heated air from the engine 12 to the first heat exchanger 30.
During the cooling mode, the openings 72 and 74 are uncovered. Subsequently, the heated air from the engine 12 is exhausted to outside through the first damper 74 by the engine fan 18 while cooler ambient air is drawn into the first heat exchanger 30 by the fan 36. Thus, during the cooling cycle, the system 20 of the present invention uses less energy to compress refrigerant vapors. It would be understood from the above discussion, that the fan 36 is rotatable in only one direction, thus reducing the complexity of the control system (not shown).
A small auxiliary type generator or alternator 79 may be provided for powering each electric motor 78 as well as the reversing valve 62. It is contemplated that about one thousand (1,000) watts of electric power will be sufficient to power the components of the system 20, power various appliances in use by the operator of such motor vehicle (not shown) and charging the main batteries. Accordingly, an auxiliary generator 80 capable of generating between about five hundred (500) watts and about eight hundred (800) watts should be sufficient in providing required electric energy. Advantageously, the diesel engine manufactured under Yanmar LV 100 brand employs a small alternator capable of providing about one hundred seventy (170) watts of power. It must be important to note that prior art electrically driven compressors and other devices require about five thousand (5,000) watt of energy. Thus, by eliminating the conversion from mechanical power at the crankshaft of the small diesel engine to electrical power in a generator and then back again from electrical power from to mechanical power in an electric powered air conditioning compressor, the costs associated with the generator and electric motor of the prior art systems are eliminated and the heating and cooling system 20 of the present invention requires significantly less electric energy than comparable prior art systems.
It will be apparent to those skilled in the relevant arm form that the ability of the system 20 of the present invention to utilize waste heat from the engine 12 during heating mode and control air flow to and from the first heat exchanger 30 by way of openings and dampers increase efficiency of the system to cool or heat the interior space of the cab 4. Furthermore, a mechanically driven compressor 22 eliminates the need for a large electrical generator thus facilitating the reduction in manufacturing costs of the system 20.
It is also within the scope of the present invention to re-circulate air passed through the first heat exchanger 30 and exhausted by the fan 34 back to the engine 12. This replaces cold ambient air with warmer air from the first heat exchanger 30. Accordingly, a second air duct 42 is installed to connect the outlet end of the blower 34 with the air inlet end of the engine 12. A damper or flap 44 controlled by an actuator 46 and a temperature sensor 48 may be provided to disable recirculation during warmer ambient temperatures.
While the system 20 has been described above as using one first heat exchanger 30 in combination with the air duct arrangement 40, it is contemplated that a pair of heat exchangers referenced as 30 a and 30 b and a pair of check valves 38 may be alternatively provided, as best shown in FIGS. 6-7.
It is also within the scope of the present invention to provide means, generally designated as 80, for operating the system 20 from a one hundred ten volt power outlet. Such arrangement is commonly referred to in the art as “shore power” and is employed when state emission mandates prohibit or significantly limit the use of APUs. Now in reference to FIG. 8, such means 80 may include a first one way clutch 82 which is secured to the engine shaft 12, an electric motor 84 capable of being connected to the source of one hundred ten volt power outlet 86, for example with a cord 88, a second one-way clutch 90 which is secured to the output shaft 92 of the electric motor 84 for rotation therewith. A belt 94 is then provided to operatively engage the pair of clutches 82, 90 and the compressor pulley 28. Thus, when the compressor 22 is operable by the engine 12, the second clutch 90 prevents rotation of the motor output shaft 92. Likewise, when the motor 84 is operable from the electrical power grid, the first clutch 82 prevents rotation of the engine shaft 14.
Although the present invention has been described in terms of the cooling and heating system 20 in use for heating an interior space of a cab 4 and/or sleeper cabin 6 of the over-the-road truck 2, it will be apparent to those skilled in the art, that the present invention may be applied to other vehicles such as bus, boat, and camper often requiring the use of APU.
Furthermore, the novel air duct and damper arrangement will be advantageous for improving efficiency of a conventional eclectically driven heating and cooling system.
Additionally, as a single cylinder air-cooled engine is advantageous in reducing the cost of operating the system 20, other engine types are also contemplated for use within the present invention.
It will be also understood that the configuration of the air ducts 40, 42 and physical location and mounting of various components of the system 20 will depend on the construction of the vehicle 2 as well as on the construction and location of the APU 10.
Thus, the present invention has been described in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same. It will be understood that variations, modifications, equivalents and substitutions for components of the specifically described embodiments of the invention may be made by those skilled in the art without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1. In combination with a vehicle including an auxiliary power system having an air cooled diesel engine and an engine fan connected to a shaft thereof and further including a heat exchange unit mounted within an interior space of said vehicle and arranged in heat exchange relationship with air in said interior space for condensing a refrigerant and heating said air during the heating mode and evaporating said refrigerant and cooling said air during the cooling mode, a reversible mode heating and cooling system for heating and cooling an interior space comprising:

(a) a compressor for compressing vaporous refrigerant, said compressor arranged in refrigerant communication with said interior heat exchange unit;

(b) a power transmission means for connecting said compressor to a rotating shaft of the diesel engine and for operating said compressor thereby;

(c) a heat exchanger mounted externally in heat exchange relationship with each of the ambient air and exhaust air from the engine, said heat exchanger further arranged in refrigerant communication with said compressor for evaporating refrigerant during the heating mode and condensing said refrigerant during the cooling mode;

(d) a blower unit in air communication relationship with said heat exchanger;

(e) a refrigerant expansion valve operatively disposed intermediate said heat exchanger and said heat exchange unit; and

(f) a refrigerant flow reversing valve operable for providing heating and cooling modes from said system by a refrigerant flow direction selection.

2. The heating and cooling system, according to claim 1, wherein said power transmission means includes a belt member and a pair of pulleys, one of said pair of pulleys is secured to the engine shaft for rotation therewith and another one of said pair of pulleys is rotatably secured to said compressor.

3. The heating and cooling system, according to claim 1, wherein said system includes an air duct means arranged in air communication with each of said engine fan and said heat exchanger for supplying engine's exhaust air thereto.

4. The heating and cooling system, according to claim 3, wherein said system includes a pair of openings formed in said air duct means, wherein one of said pair of openings is employed for directing a flow of said exhaust air from said engine to atmosphere and wherein another one of said pair of openings is employed for enabling flow of ambient air into said first heat exchanger.

5. The heating and cooling system, according to claim 1, wherein said system includes:

(a) an air duct means arranged in air communication with each of said engine fan and said heat exchanger for supplying engine's exhaust air thereto;

(b) a first opening formed in said air duct means for directing a flow of said exhaust air from said engine to atmosphere;

(c) a first damper operatively connected to said air duct means and movable for covering said first opening during heating mode and uncovering said first opening during said cooling mode;

(d) a second openings formed in said air duct means for enabling flow of ambient air into said first heat exchanger;

(e) a second damper operatively connected to said air duct means and movable for selectively covering said second opening during heating mode and uncovering said second opening during cooling mode; and

(f) means operatively connected to each of said first and second dampers and operable for moving said each of said first and second dampers to cover and uncover said first and second openings respectively.

6. The heating and cooling system, according to claim 5, said moving means includes a manually operable linkage.

7. The heating and cooling system, according to claim 5, said moving means includes a pair of electrically operable motors each of said pair of motors connected to one of said first and second dampers.

8. The heating and cooling system, according to claim 7, wherein said system includes one of a generator and alternator for supplying power to said each motor and said refrigerant flow reversing valve.

9. The heating and cooling system, according to claim 1, wherein said system includes a second air duct means for re-circulating air exhausted by said blower unit to the diesel engine during said heating mode.

10. The heating and cooling system, according to claim 9, wherein said system further includes a damper rotatably mounted within said second duct means and an electric motor coupled to a shaft of said damper for preventing recirculation of said air exhausted by said blower unit to the diesel engine during said cooling mode.

11. The heating and cooling system, according to claim 1, wherein said system includes means for operating at least said refrigerant compressor from electrical power grid.

12. The heating and cooling system, according to claim 11, wherein said means includes:

(a) a first clutch secured to the shaft of the engine for rotation therewith;

(b) an electric motor connectable to said electrical power grid;

(c) a second clutch secured to an output shaft of said electric motor for rotation therewith;

(d) a pulley rotatably mounted on said refrigerant compressor; and

(e) a belt member seated on each of said first and second clutches and said pulley, whereby said refrigerant compressor is operable by way of said first clutch during operation of the engine and is operable by way of said second clutch during operation of said electric motor from the electric power grid.

13. In combination with a vehicle including an auxiliary power system having an air cooled diesel engine and an engine fan connected to a shaft thereof and further including a heat exchange unit mounted within an interior space of said vehicle and arranged in heat exchange relationship with air in said interior space for condensing a refrigerant and heating said air during the heating mode and evaporating said refrigerant and cooling said air during the cooling mode, a reversible mode heating and cooling system for heating and cooling an interior space comprising:

(b) a heat exchanger mounted externally in heat exchange relationship with each of the ambient air and exhaust air from the engine, said heat exchanger further arranged in refrigerant communication with said compressor for evaporating refrigerant during the heating mode and condensing said refrigerant during the cooling mode;

(c) an air duct means in air communication with each of said engine fan and said heat exchanger for supplying air thereto;

(d) a blower unit in air communication relationship with said heat exchanger;

14. In combination with a vehicle including an auxiliary power system having an air cooled diesel engine and an engine fan connected to a shaft thereof and further including a heat exchange unit mounted within an interior space of said vehicle and arranged in heat exchange relationship with air in said interior space for condensing a refrigerant and heating said air during the heating mode and evaporating said refrigerant and cooling said air during the cooling mode, a reversible mode heating and cooling system for heating and cooling an interior space comprising:

(a) a compressor for compressing vaporous refrigerant;

(c) a first heat exchanger mounted externally in heat exchange relationship with exhaust air from the engine, said first heat exchanger further arranged in refrigerant communication with said compressor for evaporating refrigerant during the heating mode;

(d) a second heat exchanger mounted externally in heat exchange relationship with the ambient air, said second heat exchanger further arranged in refrigerant communication with said compressor for condensing said refrigerant during the cooling mode;

(e) a blower unit in air communication relationship with said second heat exchanger;

(f) a first refrigerant expansion valve operatively disposed intermediate said first heat exchanger and said internal heat exchange unit;

(g) a second refrigerant expansion valve operatively disposed intermediate said second heat exchanger and said internal heat exchange unit;

(h) a refrigerant flow reversing valve operable for providing heating and cooling modes from said system by a refrigerant flow direction selection;

(i) a first check valve operatively disposed intermediate said refrigerant flow reversing valve and said first heat exchanger for preventing refrigerant flow thereto during the cooling mode; and

(j) a second check valve operatively disposed intermediate said second heat exchanger and said internal heat exchange unit for preventing refrigerant flow to said second heat exchanger during the heating mode.

15. The heating and cooling system, according to claim 14, wherein said system includes said internal heat exchange unit.

16. A method for at least one of heating and cooling an interior space of a vehicle including an auxiliary power unit having an engine and an engine fan connected to a shaft thereof, said method comprising the steps of:

(a) providing a heat pump apparatus having a refrigerant compressor;

(b) connecting, with a power transmission means, said refrigerant compressor to said shaft of said engine; and

(c) selectively cooling and heating, with said heat pump apparatus, said interior space.

17. The method, according to claim 16, wherein said heating and cooling step includes the step of connecting an external heat exchanger of said heat pump apparatus in air communication means with an air exhausted from said engine.

18. The method, according to claim 17, wherein said method includes the additional step of controlling flow of each of the ambient air and engine exhaust air to an external heat exchanger of said heat pump apparatus.