WO2011019891A1

WO2011019891A1 - Cooling air supply system for a generator in a motor vehicle

Info

Publication number: WO2011019891A1
Application number: PCT/US2010/045292
Authority: WO
Inventors: Gerhard E. Delf
Original assignee: Thingap Automotive, Llc
Priority date: 2009-08-13
Filing date: 2010-08-12
Publication date: 2011-02-17

Abstract

A system for use in a motor vehicle having an internal combustion engine may include a generator configured to provide electric power to the motor vehicle and a pump configured to inject air into an exhaust stream of the internal combustion engine during an engine cold start and warm-up period and provide cooling air to the generator following the engine warm-up. The system may include a means for preventing the generator from overheating during the engine cold start and warm-up period. A method for providing cooling air to a generator on a motor vehicle having an internal combustion engine may include configuring a generator to provide electric power to the motor vehicle, and providing a pump configured to inject air into an exhaust stream of the internal combustion engine during an engine cold start and warm-up period and provide cooling air to the generator following the engine warm- up.

Description

COOLING AIR SUPPLY SYSTEM FOR A GENERATOR IN A MOTOR VEHICLE

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application

No. 61/233,576 titled "COOLING AIR SUPPLY SYSTEM FOR A GENERATOR IN A MOTOR VEHICLE," filed August 13, 2009, the entirety of which is incorporated by reference herein.

BACKGROUND

Field

[0002] The present disclosure relates to a cooling air supply system for a generator in a motor vehicle, including a turbo generator powered by exhaust gas from an internal combustion engine.

Background

[0003] Today's electrical systems for vehicles are often required to support an increasing number of electrical components, such as servo motors, onboard computers, navigation systems, and entertainment systems, just to name a few. In addition, mechanical components, such as power steering pumps, air conditioning compressors, water pumps, oil pumps and other components traditionally driven by the engine's crankshaft, are more and more being electrically powered. As the demand for electrical power continues to increase, the use of traditional power generating means becomes less attractive. Not only in terms of physical size of the alternator required to meet this demand, but also in terms of additional fuel consuming load placed on the internal combustion engine at a time when fossil fuel is in short supply, the ecological consequences are great and the demand is for reduction in fuel consumption.

[0004] Crankshaft driven generators or turbo generators, for example, may be used as a primary or secondary power source to provide or supplement the electrical power required to meet the increased demand in modern vehicles. An electrical generator's operating (efficiency) losses, however, generate heat that must be dissipated in order to prevent damage to the critical components of the electrical generator. As such, the electrical generator often requires cooling by an external air source.

[0005] As one solution to this problem, a separate air blower for the generator may be used, but the separate blower requires additional space for installation in the vehicle engine compartment, adds weight to the vehicle and must be integrated into the vehicle's engine and electrical system, adding complexity to the vehicle's electrical system and cost to the assembly of the vehicle.

[0006] Accordingly, there is a need in the art for a cost-saving and space-saving cooling air supply system to provide air cooling to a generator in a motor vehicle that does not increase the cost or ease of assembly of the vehicle and does not require additional space in the engine compartment.

SUMMARY

[0007] In accordance with certain aspects of the present invention, a system for use in a motor vehicle having an internal combustion engine includes a generator configured to provide electric power to the motor vehicle and a pump configured to inject air into an exhaust stream of the internal combustion engine during an engine cold start and warm-up period and provide cooling air to the generator following the engine warm-up.

[0008] In accordance with another aspect of the present invention, the system may include a means for preventing the generator from overheating during the engine cold start and warm-up period.

[0009] In accordance with yet another aspect of the present invention, the system may include a flow diverter configured to direct the air discharged from the pump into separate air channels for respectively injecting air into the exhaust stream and providing cooling air to the generator.

[0010] In accordance with another aspect of the present invention, the system may include a secondary air valve configured into the exhaust stream air channel to control the air injected into the exhaust stream, and a cooling air valve configured into the generator air channel to control the cooling air provided to the generator.

[0011] In accordance with another aspect of the present invention, the system may include a controller connected to the pump, the secondary air valve, and the cooling air valve, wherein the controller activates the pump, opens the secondary air valve, and closes the cooling air valve during the engine cold start and warm-up period, and wherein the controller closes the secondary air valve and opens the cooling air valve following the engine warm-up

[0012] In accordance with another certain aspect of the present invention, the system may include a generator temperature sensor connected to the controller, wherein the controller controls the pump to limit the cooling air provided to the generator to a required minimum rate based on a generator temperature signal received from the generator temperature sensor. [0013] According to another aspect of the present invention, the system may include a turbine bypass valve, wherein the controller is connected to the turbine bypass valve and opens the turbine bypass valve to selectively reduce the power output of the generator.

[0014] According to yet another aspect of the present invention, a method for providing cooling air to a generator on a motor vehicle having an internal combustion engine includes configuring a generator to provide electric power to the motor vehicle, and providing a pump configured to inject air into an exhaust stream of the internal combustion engine during an engine cold start and warm-up period and provide cooling air to the generator following the engine warm-up.

[0015] It is understood that other aspects of a cooling air supply system for a generator in a motor vehicle will become readily apparent to those skilled in the art from the following detailed description, wherein it is shown and described only exemplary configurations of a cooling air supply system for a generator. As will be realized, the invention includes other and different aspects of a cooling air supply system for a generator and the various details presented throughout this disclosure are capable of modification in various other respects, all without departing from the spirit and scope of the invention. Accordingly, the drawings and the detailed description are to be regarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE FIGURES

[0016] Various aspects of the present invention are illustrated by way of example, and not by way of limitation, in the accompanying drawings, wherein: [0017] FIG. 1 is a functional block diagram illustrating an exemplary

embodiment of an automotive system with a cooling air supply system for a generator; and

[0018] FIG. 2 is a functional block diagram illustrating an exemplary

embodiment of a cooling air supply system for a generator in a motor vehicle.

DETAILED DESCRIPTION

[0019] The present invention is described more fully hereinafter with reference to the accompanying drawings, in which various aspects of a cooling air supply system 10 for a generator in a motor vehicle are shown. This invention, however, may be embodied in many different forms and should not be construed as limited by the various aspects of the automotive system with a cooling air supply system presented herein. The detailed description of the cooling air supply system for a generator is provided below so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

[0020] The detailed description may include specific details for illustrating various aspects of a cooling air supply system for a generator. However, it will be apparent to those skilled in the art that the invention may be practiced without these specific details. In some instances, well known elements may be shown in block diagram form, or omitted, to avoid obscuring the inventive concepts presented throughout this disclosure.

[0021] Various aspects of a cooling air supply system for a generator may be illustrated by describing components that are coupled together. As used herein, the term "coupled" is used to indicate either a direct connection between two components or, where appropriate, an indirect connection to one another through intervening or intermediate components. In contrast, when a component referred to as being "directly coupled" to another component, there are no intervening elements present.

[0022] Various aspects of a cooling air supply system for a generator may be illustrated with reference to one or more exemplary embodiments. As used herein, the term "exemplary" means "serving as an example, instance, or illustration," and should not necessarily be construed as preferred or advantageous over other embodiments of a cooling air supply system disclosed herein.

[0023] Several exemplary embodiments of a cooling air supply system for a generator will now be presented. In one exemplary embodiment, a turbo generator includes a turbine coupled to an electric generator to produce electrical power. The turbine includes a turbine wheel coupled to a turbine shaft. The turbine wheel is driven by exhaust gas from an internal combustion engine source. The turbine wheel is used to rotate the turbine shaft which is coupled to the electric generator. The electric generator includes a rotor having a rotor shaft that carries a permanent magnet. The rotor shaft is coupled to the turbine shaft. The electric generator also includes a stator coil surrounding the permanent magnet.

[0024] Reference is made herein to a turbo generator. However, as those skilled in the art will readily appreciate, aspects of the present invention may extend to other applications including, by way of example, crankshaft, belt and/or gear driven generators. Accordingly, any reference to a turbo generator is intended only to illustrate various aspects of a cooling air supply system for a generator in a motor vehicle, with the understanding that these aspects have a wide range of applications. [0025] The turbo generator may include one or more cooling features to protect components of the electric generator, such as integrated cooling passages tied into the vehicle's engine cooling system and/or heat deflectors. A common emission control device, a secondary air pump, which typically injects air into the exhaust manifold of the internal combustion engine during a cold start and warm-up condition of the vehicle, may be co-used as a source of air for cooling the turbo generator.

[0026] The various aspects of a cooling air supply system presented throughout this disclosure are well suited for integration into a standard passenger vehicle (i.e., automobile). However, as those skilled in the art will readily appreciate, these aspects may be extended to other applications including, by way of example, commercial vehicles with internal combustion engines, aircraft and sea vessels with internal combustion engines, internal combustion engines driving stationary equipment (e.g., pumps, generators, etc.), or other suitable systems having an internal combustion engine source. Accordingly, any reference to an automotive system is intended only to illustrate various aspects of a cooling air supply system for a generator in a motor vehicle, with the understanding that these aspects have a wide range of applications.

[0027] FIG. 1 is a functional block diagram illustrating an exemplary embodiment of an automotive system 100 with a cooling air supply system 10. The automotive system 100 includes an internal combustion engine 102 which, in this example, is used to provide power to a drive train (not shown) to propel the vehicle. The automotive system 100 may also include a fuel system 104, an ignition system 106, an exhaust system 108, an engine cooling system 110, a lubrication system 112, a turbo generator 116, a regulator 118, and an electrical load 120, as well as other systems that are not shown. A turbine bypass valve 185 may be provided to prevent the turbo generator 116 from overheating during an engine cold start and warm-up period prior to activation of the cooling air supply system 10 by a controller 170.

[0028] The fuel system 104 may be used to provide the appropriate air-fuel mixture to the internal combustion engine 102. The air-fuel mixture may be combusted by the engine 102 when ignited by the ignition system 106 to provide power to the drive train (not shown). The exhaust gas produced from combustion of the air-fuel mixture in the engine 102 may be delivered to the atmosphere by the exhaust system 108. The engine cooling system 110 may be used to deliver a coolant to the engine 102 to dissipate heat generated from combustion. The lubrication system 112 may be used to deliver a lubricant to the moving parts in the engine 102.

[0029] The turbo generator 116 may be placed in the path of the exhaust gas flowing from the engine 102 to the exhaust system 108. As discussed above, the turbo generator 116 may include a turbine coupled to an electric generator to produce electrical power. The turbine may be a radial turbine, or some other suitable configuration. By way of example, the turbine may be an axial turbine. The electrical generator (not shown) may be directly powered by the turbine (not shown), which is driven by the exhaust gas from the internal combustion engine 102 at constantly changing rotational speeds in the range of 2,000 rpm to > 200,000 rpm and at constantly changing power outputs. The electric generator may be a three- phase permanent magnet synchronous machine, which generates three-phase AC power at rotational speeds of 5,000 rpm to > 200,000 rpm. Operation over this wide range of rotational speeds and power output may be achieved by a unique stator configuration that is described more fully below.

[0030] The three-phase AC power generated by the turbo generator 116 may be provided to the regulator 118, which rectifies and regulates the voltage before being distributed to the electric load 120. The electric load 120 represents the components in the vehicle requiring electrical power (e.g., the battery, servo motors, wiper motors, headlights, interior lights, instrumentation panels, fans, on-board computers, navigation systems, entertainment systems, etc.). The electrical load 120 also includes the ignition system 106, which is shown separately in FIG. 1 for clarity.

[0031] The lubrication system 112 may be used to deliver a lubricant to the moving parts in the turbo generator 116. The engine cooling system 110 may be used to deliver a coolant to the turbo generator 116 to protect the electric generator from the heat generated by the exhaust gas flowing through the turbine.

[0032] As shown in FIG. 2, a secondary air pump 150, which may be situated in the vehicle's engine compartment, for example, may draw air from the engine compartment and inject the air into the exhaust path of the internal combustion engine 102. The air may alternatively be drawn from an airbox containing a filter and a clean air housing, for example, or from any suitable external air source for providing air into the exhaust stream of the internal combustion engine 102. As illustrated by an air channel 152, the secondary air pump 150 may force the air into the exhaust manifold of the internal combustion engine 102, for example. During engine warm-up the engine operates on a relatively rich air/fuel mixture leaving unburned hydrocarbons in the exhaust gas. By pumping air into the exhaust stream, the secondary air pump 150 operates to provide additional oxygen which generates an exothermic reaction with the unburned hydrocarbons. That results in the reduction of hydrocarbon emissions and carbon monoxide emissions during engine warm-up. In addition, the heat generated by the exothermic reaction shortens the time for the catalytic converter to reach its operating temperature (i.e., Light-Off Temperature). Consequently, in vehicles with spark ignition engines (e.g., gasoline engines or alternative fuel spark ignition engines), the secondary air pump 150 serves as an emissions control device.

[0033] A secondary air valve 155 may be mounted on the exhaust manifold, for example, and may be a one-way valve to prevent exhaust gases from backing up into the secondary air pump 150. The secondary air pump 150 may be connected to the secondary air valve by an air tube so that only pressurized air from the secondary air pump 150 may pass from the air tube, through the secondary air valve 155, and into the exhaust stream, while exhaust gases in the exhaust stream are prevented from flowing back through the secondary air valve 155 into the air tube and/or the secondary air pump 150. Although described above as being injected into the exhaust manifold of an internal combustion engine 102, the system may be designed so that the air is injected directly into the engine's exhaust ports downstream of the exhaust valves.

[0034] In particular, the unburnt hydrocarbons (e.g., unburnt fuel and partially- burnt fuel) tend to be most concentrated during a cold start and warm-up phase of the internal combustion engine 102, until the catalytic converter attains an efficient operating temperature and the oxygen sensor is operational, for example. Accordingly, the secondary air pump 150 in conventional applications is normally set to operate for a predetermined period of time from the cold start of the internal combustion engine 102. Once the predetermined period of time elapses or a predetermined engine system parameter state has been reached, e.g., catalytic converter temperature, oxygen sensor signal, the secondary air pump 150 shuts off and the exhaust system 108 is able to operate efficiently of its own accord. As such, once the secondary air pump 150 has performed an emissions control function for the predetermined period of time from cold start, in conventional applications, the secondary air pump 150 is no longer used and is shut-off.

[0035] Aspects of the present invention include using the secondary air pump

150 to provide a cooling air flow to the turbo generator 116 to cool, in particular, the electrical components of the turbo generator 116, including the stator coil and rotor. A flow diverter, such as a Y-valve or a T-valve, for example, may be configured into the pressurized air tube, downstream from the secondary air pump 150, to provide two separate air channels, 152, described above for providing air into the exhaust stream, and 154, for supplying cooling air to the turbo generator 116. The air channels 152 and 154 may be defined by an elastomeric hose or tube, for example, or any suitable conduit for directing and delivering the air from the flow diverter toward the engine and/or the turbo generator 116. A cooling air valve 160 may be configured into the air channel 154 and connected to a controller 170 which controls the opening and closing of the cooling air valve 160 to allow or prevent cooling air to pass into the turbo generator 116.

[0036] The cooling air supply system 10 for a generator may include a

Secondary Air Supply Mode that begins when the engine starts. As shown in FIG. 2, an ignition switch 180 may be activated. The controller 170 may receive a signal indicating an engine start and activate the secondary air pump 150. At or close to the same time, the controller 170 may control the secondary air valve 155 to an open position and the cooling air valve 160 to a closed position. Thus, only the air channel 152 is open for air flow and the secondary air pump 150 serves an emissions control function by directing air through the secondary air valve 155 and into the exhaust stream at the engine's exhaust ports, for example, downstream of the exhaust valves.

[0037] The Secondary Air Supply Mode may continue for a predetermined period of time from the engine start or based on an engine system parameter state determined by the controller 170. For example, upon activation of the ignition switch 180, the controller 170 may activate the secondary pump 150, open the secondary air valve 155, and close the cooling air valve 160. The controller 170 may maintain the cooling air supply system 10 in the Secondary Air Supply Mode for up to a maximum of 200 seconds from the cold start of the engine 102, for example. Alternatively, the controller 170 may maintain the cooling air supply system 10 in the Secondary Air Supply Mode for a period of time based on the engine system parameter state, such as a catalytic converter temperature and/or an oxygen sensor signal.

[0038] To prevent the turbo generator 116 from overheating during the

Secondary Air Supply Mode, when the secondary air pump 150 is dedicated to forcing air into the exhaust stream of the internal combustion engine 102, a power output of the turbo generator 116 may be reduced. The power output of the turbo generator 116 may be reduced until the controller 170 opens the cooling air valve 160 by opening a turbine bypass valve 185, for example. As shown in FIG. 2, the controller 170 may partially open the turbine bypass valve 185 to permit a portion of the exhaust stream directed to the turbo generator to bypass the turbine. The associated reduction in air flow to the turbine results in a corresponding reduction in turbine shaft power, which results in a reduction of power output through the generator and prevents the generator from overheating.

[0039] Upon conclusion of the predetermined period of time, the controller 170 activates a Transition Mode to convert the secondary air pump 150 from an emissions control device to a cooling air supply source. The controller 170 may configure the secondary air valve 155 to a closed position and the cooling air valve 160 to an open position. The turbine bypass valve 185 may be closed so that the turbo generator 116 receives the full flow of exhaust gas and operates at full capacity, for example.

[0040] During a Cooling Air Supply Mode, the system's air flow is thus prevented from flowing through the air channel 152 into the exhaust stream and, instead, is converted to flowing through the air channel 154. The external air drawn into the system by the secondary air pump 150 thus flows through the air channel 154 and the cooling air valve 160 into the turbo generator 116. The cooling air passes through the turbo generator 116, conducting heat energy away from the critical components of the electrical generator, and exits through a check valve 190. The check valve 190 may prevent water and other contaminant intrusion into the generator space when there is no cooling air flow through the turbo generator 116.

[0041] In accordance with yet another aspect of the present invention, a generator temperature sensor (not shown) may be employed inside the turbo generator 116 and connected to the controller 170. During the Cooling Air Supply Mode, for example, the controller 170 may control the secondary air pump 150 to limit the air flow rate through the turbo generator 116 to a minimum flow rate required for cooling the turbo generator 116 based on a generator temperature signal received from the generator temperature sensor. Controlling the air flow rate allows the cooling air supply system 10 to keep the electric power consumption of the secondary air pump 150 to a minimum required level, keeping the electric load that the pump adds to the vehicle's electrical system at a minimum while providing cooling the generator.

[0042] The various aspects of this disclosure are provided to enable one of ordinary skill in the art to practice the present invention. Modifications to various aspects of a cooling air supply system for a generator in a motor vehicle presented throughout this disclosure will be readily apparent to those skilled in the art, and the concepts disclosed herein may be extended to other applications with an internal combustion engine exhaust gas source. Thus, the claims are not intended to be limited to the various aspects of a turbo generator presented throughout this disclosure, but are to be accorded the full scope consistent with the language of the claims. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U. S. C. §112, sixth paragraph, unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for."

Claims

WHAT IS CLAIMED IS:

1. A system for use in a motor vehicle having an internal combustion engine, comprising:

a generator configured to provide electric power to the motor vehicle; and

a pump configured to inject air into an exhaust stream of the internal combustion engine during an engine cold start and warm-up period and provide cooling air to the generator following the engine warm-up.

2. The system according to claim 1 , further comprising:

a means for preventing the generator from overheating during the engine cold start and warm-up period.

3. The system according to claim 1 , wherein the engine cold start and warm-up period corresponds to a predetermined period of time elapsed from engine start.

4. The system according to claim 1 , wherein the engine cold start and warm-up period is determined by a predetermined engine system parameter state being reached after engine start.

5. The system according to claim 4, wherein the predetermined engine system parameter state comprises a catalytic converter temperature.

6. The system according to claim 4, wherein the predetermined engine system parameter state comprises an oxygen sensor signal reading.

7. The system according to claim 1 , further comprising:

a flow diverter configured to direct the air discharged from the pump into separate air channels for respectively injecting air into the exhaust stream and providing cooling air to the generator.

8. The system according to claim 7, wherein the flow diverter is a T-valve or a Y-valve.

9. The system according to claim 7, further comprising:

a secondary air valve configured into the exhaust stream air channel to control the air injected into the exhaust stream, and

a cooling air valve configured into the generator air channel to control the cooling air provided to the generator.

10. The system according to claim 9, wherein the secondary air valve is a one-way valve that prevents gases from the exhaust stream from flowing through the secondary air valve toward the pump.

11. The system according to claim 9, further comprising:

a controller connected to the pump, the secondary air valve, and the cooling air valve; wherein the controller activates the pump, opens the secondary air valve, and closes the cooling air valve during the engine cold start and warm-up period; and

wherein the controller keeps the pump activated, closes the secondary air valve, and opens the cooling air valve following the engine warm-up.

12. The system according to claim 11 , further comprising:

a generator temperature sensor connected to the controller, wherein the controller controls the pump to limit the cooling air provided to the generator to a required minimum rate based on a generator temperature signal received from the generator temperature sensor.

13. The system according to claim 11 , further comprising a turbine bypass valve, wherein the controller is connected to the turbine bypass valve and opens the turbine bypass valve to selectively reduce the power output of the generator.

14. The system according to claim 13, further comprising:

a generator temperature sensor connected to the controller, wherein the controller controls opening the turbine bypass based on a generator temperature signal received from the generator temperature sensor.

15. The system according to claim 7, further comprising: a check valve configured into a cooling air exit channel to prevent water and/or other contaminants from entering the generator when the cooling air valve is closed.

16. The system according to claim 1 , wherein the generator is a turbo generator having a turbine coupled to an electric generator and driven by the exhaust stream from the internal combustion engine.

17. The system according to claim 1 , wherein the generator is a belt driven generator or a gear driven generator.

18. A method of providing cooling air to a generator on a motor vehicle having an internal combustion engine comprising:

configuring the generator to provide electric power to the motor vehicle; and

providing a pump configured to inject air into an exhaust stream of the internal combustion engine during an engine cold start and warm-up period and provide cooling air to the generator following the engine warm-up.

19. The method of claim 18, further comprising:

providing a means for preventing the generator from overheating during the engine cold start and warm-up period.

20. The method of claim 18, wherein the engine cold start and warm-up period corresponds to a predetermined period of time elapsed from engine start.

21. The method of claim 18, wherein the engine cold start and warm-up period is determined by a predetermined engine system parameter state being reached after engine start.

22. The method of claim 21 , wherein the predetermined engine system parameter state comprises a catalytic converter temperature.

23. The method of claim 21 , wherein the predetermined engine system parameter state comprises an oxygen sensor signal reading.

24. The method of claim 18, further comprising: providing a flow diverter configured to direct the air discharged from the pump into separate air channels for respectively injecting air into the exhaust stream and providing cooling air to the generator.

25. The method of claim 24, wherein the flow diverter is a T-valve or a Y- valve.

26. The method of claim 24, further comprising:

configuring a secondary air valve into the exhaust stream air channel to control the air injected into the exhaust stream, and

configuring a cooling air valve into the generator air channel to control the cooling air provided to the generator.

27. The method of claim 26, wherein the secondary air valve is a one-way valve that prevents gases from the exhaust stream from flowing through the secondary air valve toward the pump.

28. The method of claim 26, further comprising:

connecting a controller to the pump, the secondary air valve, and the cooling air valve;

wherein the controller activates the pump, opens the secondary air valve, and closes the cooling air valve during the engine cold start and warm-up period; and

wherein the controller closes the secondary air valve and opens the cooling air valve following the warm-up.

29. The method of claim 28, further comprising:

connecting a generator temperature sensor to the controller, wherein the controller controls the pump to limit the cooling air provided to the generator to a required minimum rate based on a generator temperature signal received from the generator temperature sensor.

30. The method of claim 28, further comprising:

connecting the controller to a turbine bypass valve, wherein the controller controls opening the turbine bypass valve to selectively reduce the power output of the generator.

31. The method of claim 30, further comprising:

connecting a generator temperature sensor to the controller, wherein the controller controls opening the turbine bypass based on a generator temperature signal received from the generator temperature sensor.

32. The method of claim 24, further comprising:

configuring a check valve into a cooling air exit channel to prevent water and/or other contaminants from entering the generator when the cooling air valve is closed.

33. The method of claim 18, wherein the generator is a turbo generator having a turbine coupled to an electric generator and driven by the exhaust stream from the internal combustion engine.

34. The method of claim 18, wherein the generator is a belt driven generator or a gear driven generator.