EP0996815A1

EP0996815A1 - Oil-cooled internal combustion engine with motor-assisted turbofan cooling

Info

Publication number: EP0996815A1
Application number: EP99916598A
Authority: EP
Inventors: Edward M. Halimi; William E. Woollenweber
Original assignee: Turbodyne Systems Inc
Current assignee: Honeywell International Inc
Priority date: 1998-04-21
Filing date: 1999-04-08
Publication date: 2000-05-03
Also published as: WO1999054604A1

Abstract

An exhaust-driven cooling system (13) for an internal combustion engine system (10) permits cooling system components (20, 22-25, 30) to be located at locations (152) that do not interfere with the aerodynamics of a vehicle (150) and do not endanger the reliability of engine operation and also permits the engine lubricating fluid, preferably synthetic oil, to be used as the engine coolant, eliminating a separate coolant, such as the water-antifreeze mixture most commonly in use. In the invention, the cooling system components, such as a turbocooling assembly (110) of the invention, are not mechanically connected to the internal combustion engine (11) and can more reliably and effectively cool an internal combustion engine (11).

Description

OIL-COOLED INTERNAL COMBUSTION ENGINE WITH MOTOR-ASSISTED TURBOFAN COOLING

Field of Invention

This invention relates generally to internal combustion engine systems with exhaust-driven cooling systems and a single fluid for engine lubrication and cooling, vehicles with such systems, and methods and apparatus therefor.

Background of Invention

The cooling load on modern, heavy-duty engines has forced the cooling system components to become larger, more complex, and more expensive.

The engines and auxiliary equipment used to power many types of off-highway equipment, such as farm machinery and earth movers, require the use of as many as five separate heat exchangers, such as an engine coolant heat exchanger, an charge air cooler, an hydraulic oil cooler, an engine lube oil cooler, and often an air-conditioning condenser.

Most internal combustion engines in commercial and industrial use employ a cooling system that uses water or a water and antifreeze coolant mixture to cool the internal combustion engines. Water freezes at 32 degrees

F. (0° C), and such engines are usually protected against damage that can be caused by the expansion of freezing water by adding antifreeze to the water.

The water-antifreeze coolant mixture is circulated through inner passages formed in the engine to dissipate the heat generated during engine operation. The heated coolant mixture is then delivered to an engine radiator where the heat is transferred from the coolant mixture to air flowing through the engine radiator.

While such water-based cooling systems are generally satisfactory, the introduction of antifreeze into the coolant for the internal combustion engine adds a possible source of unreliability. Water also provides a source of corrosion and rust in the engine, and such water-based cooling systems require additional engine accessories such as water pumps, radiators and hoses, and fans and belts.

The engine radiator is commonly located in the front of a vehicle where air can be directed through the radiator as a result of movement of the vehicle. A fan, mechanically driven by the engine, is also required to induce ambient air through the radiator to cool the engine coolant while the vehicle is stationary. The efficiency of such fans is generally low and such fans drain engine power and reduce the useful output of an engine.

The use of a single fluid to both cool and lubricate an internal combustion engine is disclosed in such references as U.S. Patent No.

4,708,095, November 24, 1987, by Luterek, and U.S. Patent No. 2,078,499, February 4, 1931, by Lungstrom. However, radiators that are located at the front of the vehicle and rely on a fan mechanically driven by the engine have been used to transfer heat from the oil to the atmosphere. Such radiators are exposed to damage in the event at a vehicle collision. In the case of an accident, where the radiator is damaged, leakage of the cooling oil presents a fire hazard compared to conventional cooling systems using water antifreeze coolant.

The feasibility of the design of a turbine-driven cooling fan system has been investigated in W.E. Woollen weber's doctoral dissertation, entitled The

Thermodynamic Basis For Tlie Design of Turbine-Driven Fan Systems To Provide Cooling Air For Engine and Vehicle Exchangers, 1993, on file in the California Coast University Library. A condensation of this investigation has been published in SAE Paper No. 940842, entitled Turbo-Compound Cooling Systems For Heavy-Duty Diesel Engines, by W.E. Woollenweber. Systems for cooling vehicle operating fluids with turbine-driven fans have been described in U.S. Patent No. 4,885,911, December 12, 1989, and U.S. Patent No. 4,918,923, April 24, 1990, both by Woollenweber, et al.

The success of turbine-driven cooling systems for internal combustion engines is dependent upon the quantity and availability of exhaust gas energy.

At high engine speed, there is an abundance of exhaust gas energy, so much

-2- that in some instances it becomes necessary to incorporate a waste gate in the exhaust system. However, the amount of exhaust gas energy decreases as engine speed is reduced, and at low idle speeds where exhaust gas flow is minimal, the exhaust gas energy level is frequently inadequate to provide an acceptable flow of cooling air from a turbine driven fan. Where there is a demand for an appreciable amount of cooling airflow at low idle speed, a turbine-driven fan system may not be capable of meeting the demand.

Summary of the Invention This invention provides an exhaust-driven cooling system for an internal combustion engine system, permitting cooling system components to be located at locations that do not interfere with the aerodynamics of a vehicle and do not endanger the reliability of engine operation and also permits the engine lubricating fluid, preferably a synthetic oil, to be used as the engine coolant, eliminating a separate coolant, such as the water-antifreeze mixture most commonly in use. In the invention, the cooling system components such as a turbocooling assembly of the invention, are not mechanically connected to the internal combustion engine and can more reliably and effectively cool an internal combustion engine. An internal combustion engine system of the invention comprises an internal combustion engine, means for providing a cooling flow of engine lubricant to and from the internal combustion engine for carrying heat generated by the internal combustion engine away from the internal combustion engine, an engine lubricant cooler, or heat exchanger, connected with the means for providing a cooling flow of engine lubricant, and a turbocooler assembly including a turbine connected with the internal combustion engine exhaust gas and a ducted fan driven by the turbine to provide a flow of cooling air to the engine lubricant cooler. Preferred turbocooler assemblies of the invention include an electric motor for assisting the turbine in driving the fan and providing a flow of cooling air. The invention provides a motor-assisted turbocooler assembly that can be mounted on a vehicle and located away from the internal combustion engine. Such a motor-assisted turbocooler comprises a combined motor- turbine driving section and a ducted fan section including an engine lubricant cooler. The motor-turbine driving section of the turbocooler may be connected with an engine's exhaust manifold through a suitable exhaust gas conduit, and the assisting motor may be connected with an engine electrical system through an accompanying control to provide electric energy to drive the ducted fan section so it provides a controlled flow of cooling air to the engine lubricant cooler under all engine operating conditions.

In preferred embodiments of motor-assisted turbocooler assembly, the windings of the assisting motor are in heat transfer relationship with the ducted fan section. In such preferred embodiments a cooling air duct can carry the motor windings, and a bearing housing for the motor-assisted turbocooler assembly can provide an air passageway through an interior opening of the bearing housing so rotation of the shaft and fan blades can provide airflow through the assembly for cooling the shaft bearings and motor windings.

The invention provides a method of providing cooling for an internal combustion engine, comprising: providing the internal combustion engine with a cooling flow of engine lubricant, using the exhaust gas energy of the internal combustion engine for generating a flow of cooling air, and directing the flows of engine lubricant and cooling air into a heat transfer relationship for cooling the engine lubricant. The method of the invention can include sensing at least one condition indicative of an inadequate flow of air, and thereupon using electrical energy from the internal combustion engine for at least assisting the exhaust gas energy in the generation of the flow of cooling air. Further, the use of electrical energy can be controlled in the invention to assist the generation of the flow of cooling air at low engine speed, at low cooling airflows, and at unacceptably high engine lubricant temperatures. In the invention, the engine lubricant is preferably a synthetic oil, and the exhaust gas energy and electrical energy are controlled to maintain its temperature at least about 300 degrees F. and below its degradation temperature.

The invention can thus provide a cooling method for use with an oil- only internal combustion engine system by providing a cooling flow of engine oil, converting exhaust gas energy of the oil-only internal combustion engine to rotational energy for rotating a fan, producing a flow of cooling air for the oil-only internal combustion engine system with the fan, cooling the flow of engine oil with the flow of cooling air, converting electrical energy from the internal combustion engine system to rotational energy for rotating the fan upon demand, and generating a demand signal for initiating and terminating the conversion of electrical energy to rotational energy for rotating the fan upon unacceptable cooling in the system.

Further features and advantages of the invention will be apparent from the drawings and more detailed description of the invention that follows.

Detailed Description of the Drawings

Fig. 1 is a schematic representation of an internal combustion engine system of this invention with an exhaust-driven engine cooling system;

Fig. 2 is a cross-sectional schematic view of the turbocooling assembly of the invention taken at a plane through its central axis;

Figs. 3A and 3B depict one method of incorporating an internal combustion engine system of the present invention in a vehicle and the resulting vehicle; Fig. 2A depicting a side view of, and Fig. 2B depicting a view from above, the truck tractor; Fig. 4 is a cross-sectional view of a preferred embodiment of a turbofan assembly with a motor-assist, taken at a plane through its central axis of rotation; and

Figs. 5Λ and 5B depict a cooling system module of the invention with an industrial internal combustion engine.

-5- Detailed Description of the Invention

Figs. 1 and 2 illustrate an internal combustion engine system of the invention and a truck tractor incorporating the invention.

As illustrated in Fig. 1 an internal combustion engine system 10 of the invention can comprise an internal combustion engine assembly 11, for example, a multi-cylinder internal combustion engine such as a heavy duty diesel engine designed for use in a truck tractor. The internal combustion engine 11 includes or is provided with means 12 for providing a flow of lubricant to and from the internal combustion engine assembly for carrying heat generated by the operation of the internal combustion engine assembly away from the internal combustion engine assembly 11 for dissipation to atmosphere. The means 12 can comprise the integral oil reservoir and oil pump of the internal combustion engine which also provides a flow of lubricant in the internal combustion engine assembly 11 for lubricating its moving parts, or can comprise supplemental elements for the internal combustion engine assembly 11 providing an oil reservoir of increased capacity and a supplemental oil pump to provide a flow of cooling engine lubricant to a remotely located cooling system 13 of the invention, as described in greater detail below. Means 12 can provide a cooling flow of lubricant to the remotely located cooling system 13 through an oil conduit 14 and can receive cooled lubricant from the remotely located cooling system 13 through another oil conduit 15.

As shown in Fig. 1 , the remotely located cooling means 13 comprises an oil cooler 20, connected with the conduit means 14 and 15 providing a flow of cooling lubricant to and from the internal combustion engine assembly 11, and a fan assembly 21. The turbofan assembly 21 includes an exhaust gas driven turbine 22 connecting with conduit means 16 for carrying the exhaust gas product of the combusted fuel air mixture, indicated by the open arrow E in Fig. 1, from the exhaust gas manifold 17 of the internal combustion engine 11. The exhaust gas E flows through the exhaust gas volute 23 and the exhaust gas turbine 22 and is exhausted from the turbofan assembly 21 as

-6- indicated by the open arrow G of Fig. 1. Turbofan assembly 21 also includes a ducted fan means 24 driven by the turbocooler turbine 22. The ducted fan means communicates with atmosphere and draws air into the turbofan assembly 21, as indicated by the open arrow AI. The ducted fan means 24 provides a flow of cooling air through means 25 for directing the flow of cooling air through the oil cooler 20 to the cool the engine lubricant and dissipate the heat generated in operation of the internal combustion engine with the air out flow, indicated by the open arrow AO.

In the preferred internal combustion system of the invention, the cooling system 13 is motored-assisted, that is, the turbofan assembly 21 is provided with a means 30 providing a motor-generated assist to supplement the exhaust gas energy when the internal combustion engine 11 provides insufficient exhaust gas for adequate dissipation of the heat generated in operation of the internal combustion engine. Preferably, the means 30 for providing the ducted fan means with supplemental rotational energy comprises an electric motor 31 (indicated in dashed lines in Fig. 1) located within the turbofan assembly 21, preferably between the exhaust-driven turbine 22 and the ducted fan 24. Such an electric motor can be operated from the battery 32, or other source of electric energy, of the internal combustion engine system by an electrical control 33 which may be added to an internal combustion engine system with a cooling system 13. The electric motor control system, which is shown in dashed lines, can operate the electric motor 31 in response to signals from one or more sensors, for example, an engine speed sensor 34 at the internal combustion engine 11 , an exhaust gas pressure sensor 35 at the internal combustion engine, an airflow sensor 36 in the flow of cooling air to the oil cooler 20 and/or lubricant temperature sensor 37 located at the oil cooler 20, or as shown in Fig. 1, at the oil conduit 15 adjacent the oil cooler 20. The control 33 for electric motor 31 may be located at the location of either the internal combustion engine 11 or the cooling system 13, whichever is most convenient, and the signals from the sensors controlling operation of the electric motor 31 may be connected with the control 33 over the electric connections as indicated by the dashed lines in Fig. 1.

In operation the internal combustion engine system 10 provides a method of cooling the internal combustion engine by: providing the internal combustion engine 11 with a cooling flow of engine lubricant ( e.g., through operation of the means 12 for providing a flow of cooling lubricant to and from the internal combustion engine and the turbocooling system 13); using the exhaust gas energy of the internal combustion engine for generating a flow of cooling air (e.g., through the use of the exhaust gas E from the exhaust gas manifold 17 of the internal combustion engine by the exhaust gas driven turbine 22 of the turbofan assembly); directing the flows of engine lubricant and cooling air into a heat transfer relationship for cooling the engine lubricant (e.g., through the use of the oil cooler 20 and ducted cooling airflow of the turbocooler system 13); and, in preferred methods of operation, using electric energy from the internal combustion engine for at least assisting the exhaust gas energy in the generation of the flow of cooling air (e.g. , through operation of the motor-assist 31 by control 33 from the internal combustion engine electrical source 32.) In such preferred methods, the motor assist 31 can be operated by sensing the engine speed of the internal combustion engine (e.g., by sensor 34) and using the electrical energy (e.g. , from the internal combustion engine battery 32) for generation of the cooling airflow when the engine speed is too low to provide an acceptable exhaust gas energy. The turbocooling motor assist 31 can also be operated by sensing the temperature of the engine lubricant being cooled by the flow of cooling air (e.g. , by a temperature sensor 37) and controlling the electrical energy (e.g. , battery 32) in the generation of the flow of cooling air when the engine lubricant temperature is too high (or when a synthetic oil is used as engine lubricant when the engine lubricant temperature falls below a temperature of about 300 degrees F.) Further possible methods of the invention include sensing a flow of cooling air (e.g. , by sensor 36) and using the electrical energy (e.g., battery

32) for generation of the flow of cooling air when the flow of cooling air is

-8- unacceptably low and/or sensing the exhaust gas pressure (e.g., by sensor 35) and using the electrical energy (e.g., battery 32) for generation of the flow of cooling air when the exhaust gas pressure is unacceptably low.

If desired, heat exchangers for other working fluids associated with the internal combustion engine system may also be incorporated into the turbocooling system 13, for example, by inclusion in means 25 for directing cooling air from the ducted fan 24 for cooling within the cooling system 13. As indicated above, most generally the control 33 applies to electrical energy from a source of electrical energy of an electrical system of the internal combustion engine 11, or from a separate auxiliary all electrical energy source, when the exhaust gas energy of the internal combustion engine is insufficient to provide an acceptable flow of cooling air for the oil cooler 20 and any other heat exchangers that may be included in the turbocooler assembly. Control 33 can receive signals from any one or more sensors for operating conditions of the internal combustion engine or of the cooling system

13. For example, control 33 may be connected with an engine speed sensor on the internal combustion engine over connection 34a to operate the motor 31 when the internal combustion engine is operating at idle or low speeds where the exhaust energy is low and may not provide an acceptable rotating speed for the cooling system 13. In addition, or in place of engine sensor 34, the cooling system 13 may be provided with a sensor 36, either upstream or downstream of the oil cooler 20 to provide a signal over connection 36a to indicate an insufficient airflow through the oil cooler and/or other heat exchangers. Further, in place of or in addition to such sensors, the control 33 may be provided with signals from temperature sensors, such as the temperature sensor 37, which may be located at various locations in the internal combustion engine system 10, such as in means 12, conduit 15, or oil cooler 20, to indicate when insufficient cooling is taking place in the engine lubricant or any other working fluids being cooled by the turbocooler assembly 13. Thus, the invention eliminates the use of water or a water-antifreeze mixture for engine cooling and can provide internal combustion engine systems with a single operating fluid, preferably a synthetic oil. The cooling system 13 receives with the flow of the engine lubricant (for example, over conduit 14), the heat generated in operation of the internal combustion engine 11, and oil cooler 20 transfers a requisite amount of this heat to the flow of cooling air AI, AO through the cooling system 13.

Although not shown in Fig. 1 , the internal combustion engine system of Fig. 1 can include means for providing a mixture of fuel and air to the internal combustion engine assembly 11 , which can comprise a turbocharger

(or in V-type internal combustion engine systems, two turbochargers). The turbocharger or turbochargers can provide, as well known in the art, a flow of pressurized charge-air for delivery to cylinders internal combustion engine assembly 11. In addition, such an internal combustion engine system can include one or more intercoolers for the compressed charge air.

Fig. 2 is a cross-sectional view of the turbocooling assembly 130 taken at a plane through its central axis. As illustrated by Fig. 2, the turbocooling assembly 130 includes a motor-assisted turbofan assembly 110 an annular diffuser assembly 50 connected with a ducted fan portion 112 of the turbofan assembly 110, an air inlet assembly 60 connected with and enclosing air inlet means 116 of the turbofan assembly 110, and at least one heat exchanger 20. As illustrated in Fig. 2, the heat exchanger 20 of the turbocooling assembly 130 can be connected with a means 12 for providing a flow of lubricant of an internal combustion engine 11 (not shown in Fig. 2) by means of conduits 14, 15 (as shown in Fig. 1), and operation of the turbofan assembly 110 will draw cooling air through the heat exchanger 20, as shown by the open arrow AI. Although Fig. 2 illustrates only one heat exchanger 20, a plurality of heat exchangers can be included in the air inlet enclosure 61 around its periphery, and air can be drawn through the plurality of heat exchangers by operation of the turbofan assembly 110, in the manner indicated above for heat exchanger

20.

-10- Figs. 3A and 3B illustrate a truck tractor 150 incorporating the invention. In the embodiment illustrated in Figs. 3A and 3B (and Fig. 2) the cooling system 13 has been incorporated into turbocooling assembly 130. Since the turbocooling assembly 130 employs exhaust gas energy and, preferably, electrical energy from the internal combustion engine, the internal combustion engine system 10 of the invention does not require cooling components mechanically driven by the internal combustion engine 11, and in the invention, the internal combustion engine cooling system 13 which is embodied in turbocooling assembly 130, may be located anywhere within a vehicle and operated through flexible exhaust gas conduits and electrical conduits (e.g., conduits 14, 15, 16 and 31a of Fig. 1). In addition, the invention eliminates the necessity of locating the internal combustion engine 11 at the front of the vehicle to take advantage of the forced flow of cooling air through a cooling system radiator as in the past. Thus, with the invention, the front of the vehicle may be reshaped for improved aerodynamics and improved savings of fuel consumption through the reduced drag associated with the reshaped vehicle.

As indicated in Fig. 3A, the truck tractor may incorporate a radiator- less oil cooled internal combustion engine 11 , which may be located at a location other than the front of the vehicle, for example, as indicated in Fig.

3A adjacent the rear wheels 151 , behind the location 152 of the vehicle operator. The turbocooling assembly 130 may be located at the top of the truck tractor, as indicated in Figs. 3 A and 3B. Internal combustion engine 11 may be connected with the turbocooling assembly 130 through conduits for oil (e.g. , 14, 15 of Fig. 1), and for electrical energy and signals, (e.g., 31a and

36a) as indicated in Fig. 1 (but not in Figs. 3 A and 3B). The air input AI for the turbocooling assembly 130 may be drawn from atmosphere through a plurality of shutters 153 in a forward facing portion of the tractor trailer above the operator cab and away from the road surface where the air is cleaner. By placing the air inlet for the turbocooling assembly 130 in a forward facing surface, vehicles of the invention can take advantage of the forward movement

-11- of the vehicle to assist the turbocooling assembly 13 in providing an air input AI for cooling the internal combustion engine. As shown in Fig. 3A, the truck tractor enclosure cab can be aerodynamically designed with a sharply sloping front surface 154 substantially reducing the aerodynamic drag over the tractor 150 and blending airflow over the tractor with a trailer 160, which can eliminate the need for air deflectors which are in common use on truck tractors. For example, the frontal surfaces 154 of such a vehicle can form included angles with the road surface as little as about 40 degrees to 45 degrees. Such a sharply sloping front can be blended into trailers behind and reduce the drag of loads being pulled over the road. In addition, by removing radiators and internal combustion engine parts from the front of the vehicles, the invention avoids dangers that may be associated with oil spills in the event of a front end collision and eliminates the possibility of damage to the engine radiator in the event of front collision or from road debris. Fig. 4 shows a preferred turbofan assembly 110 of the turbocooling assembly 130 of Figs. 2 and 3, which can be used in the cooling system 13 of Fig. 1. The turbofan assembly 110 comprises a combined motor-turbine driving section 111 and a ducted fan section 112 sharing a common rotating shaft 113. The first end 113a of the rotating shaft 113 carries a plurality of turbine blades 114 and the second end of the rotating shaft 113b carries a plurality of fan blades 117. The combined motor-turbine section 111 includes an exhaust gas volute 115 directing engine exhaust gas GI through a volute inlet 115a and through the plurality of turbine blades 114 to rotate the shaft 113 and outwardly through opening 115b as GO. The ducted fan section 112 includes an intake means 116 encompassing the plurality of fan blades 117 and providing an air inlet 116a. In the preferable motor-assisted turbofan assembly 110 of Fig. 4, the cooling air duct 116 and its inlet 116a are arranged around the central portion of the rotating shaft 113 between the turbine blades 114 and fan blades 117. The central portion of the rotating shaft 113 is carried by a bearing assembly 118, which is in turn carried by a bearing housing 140.

-12- The combined motor-turbine section is provided with a plurality of magnets 120 mounted on the central portion of the rotating shaft 113, and a plurality of motor windings 121 are located adjacent the magnets as shown in Fig. 4, and connected to the control means 33 through electrical conduits 49. Electrical power from source 32 can be controlled by control means 33, as set forth above, and can be converted into polyphase electrical signal applied over the electrical motor conduits 49 to the plurality of motor windings 121 to create a rotating magnetic field. The interaction of the electrical energy applied to the motor windings 121 and the magnets 120, which are fastened to the rotating shaft 113, converts electrical energy from the power source 32 into rotational energy to drive the plurality of fan blades 117. As shown in Fig. 4, in preferred motor-assisted turbofan assemblies 110, the motor windings 121 are carried in heat transfer relationship with cooling air duct 116, which acts as a heat sink conducting the heat generated by electrical losses of the motor windings 121 to the cooling air duct 116 which is, of course, cooled by the cooling air urged through the duct 116 by the rotating fan blades 117.

Further cooling for the motor-assisted turbocooling assembly 110 can be effected by providing a substantially air-tight connection 142 of the cooling air duct 116 to the bearing housing 140, and providing a passageway for cooling air adjacent the bearing assembly 118 and motor windings 121. The bearing housing 140 can be joined to the air duct 116 in a substantially airtight joint 142 and the bearing housing 140 can be provided with an air opening 141 connectable with ambient air from the engine air cleaner (not shown). The cooling air duct 116 can be provided with an interior opening

116b adjacent the plurality of motor windings 121 and upstream of the rotating fan blades 117. As so constructed, the preferred motor-assisted turbocooling assembly 110 of the invention forms an air passageway 143 within the turbocooling assembly 110, and rotation of the fan blades 117 draws air into the air opening 141 of the bearing housing 140 through the passageway 143 and around the motor windings 121 and outwardly through the interior opening

-13- around the motor windings 121, the flowing air provides cooling for the bearings 118 and motor windings 121 of the assembly 110.

Thus, with the invention, any deficiency in the exhaust gas energy at low idle or low engine speeds of the internal combustion engine 11 can be supplemented from energy from an electrical power source, such as battery 32, and an acceptable speed of rotation and cooling airflow from the fan blades can be maintained in the turbofan cooling system.

In operation of the internal combustion engine system 10, exhaust gas from the internal combustion engine is directed to the volute 115 and through a turbine inlet opening 115a which directs the exhaust gas through the plurality of turbine blades 114 where energy is absorbed from the exhaust gas stream and converted to rotational energy for driving the rotating shaft 113 and fan blades 117. Rotation of the fan blades 117 draws airflow "AI" into the air intake means 116 which is urged outwardly from the fan blades 117 through the ducted fan section 112 as airflow "AO". The application of electrical energy to the motor stator windings 121 can rotate the plurality of fan blades 117 in the event the energy of the exhaust gas is insufficient to acceptably rotate the plurality of turbine blades 114. Operation of the fan blades 117 also urge air through the air opening 141 through the bearing housing 140 and around the electric motor windings 12 to carry away energy lost in electric motor as heat. In the turbocooling assembly 130, the airflow generated by operation of the turbofan assembly 110 passes through the oil heat exchanger 20 (as shown in Fig. 2) and cools the flow of engine lubricant. The invention provides a method of generating a flow of cooling air for an oil-only internal combustion engine system by providing a cooling flow of engine lubricant for the engine, converting the exhaust gas energy of the engine to rotational energy for rotating a fan that produces a flow of cooling air for cooling the flow of engine lubricant from the internal combustion engine, and by converting electrical energy to rotational energy for the fan in response to demand signals from conditions in the internal combustion engine

-14- system, and/or in the flow of cooling air or engine lubricant, indicating unacceptable cooling, such as low engine operating speeds, excessive temperatures in the system, inadequate cooling airflow and the like.

Another feature of the present invention is the use of synthetic oil for both cooling and lubricating the internal combustion engine. Since synthetic oils have higher oxidation temperatures than mineral oils, it is possible to operate engines with oil sump temperatures of 300 degrees F. because the heat rejection is less than in water cooling systems. This allows the use of smaller heat exchangers and lowers the horsepower needed to drive the cooling fan. Further, the internal engine friction is lessened by using higher lubricating oil temperature, which results in better fuel consumption due to lower lube oil viscosity.

A turbocooling assembly 130 can also provide cooling for stationary industrial engines, as illustrated in system 100 of Figs. 5Λ and 5B. In Figs. 5A and 5B, one or more heat exchangers 104 are located horizontally at the top of the turbo-cooling assembly 130. A conventional fan-radiator cooling system 106 is shown in dotted lines to illustrate the size advantages made possible by this invention. For example, the smaller vertical height of the cooling package allows a reduction in size of the shipping container when the industrial engine system is transported to its ultimate destination.

Thus, the invention also comprises a unique combination of components consisting of an internal combustion engine that uses synthetic oil to lubricate and cool the engine, and turbocooling assembly, including a motor-assisted turbo fan assembly and concentric annular diffusers, in a cooling module with peripheral heat exchangers. In vehicles, the turbocooling assembly of the invention may be located away from the front of the engine in protected or safer areas particularly in commercial and military vehicles. In operation, the synthetic cooling and lubricating oil is allowed to reach sump temperatures of 300 to 350 degrees F. in order to lower engine friction losses and improve fuel consumption. The electric motor of the preferred turbofan assembly can

-15- assist in maintaining adequate cooling airflow at low engine speeds, or when the exhaust gas energy level is low.

While the invention has been described with respect to currently known preferred embodiments and best mode of operation, those skilled in the art will clearly recognize that other embodiments and methods of operation are possible without departing from the scope of the invention as defined by the following claims and prior art.

-16-

Claims

We Claim:

1. An internal combustion engine system, comprising: a multi-cylinder, internal combustion engine assembly; means for carrying the exhaust gas product of a combusted fuel- air mixture from the internal combustion engine assembly; means for providing a flow of lubricant for lubricating the internal combustion engine assembly and for carrying heat generated by operation of the internal combustion engine assembly away from the internal combustion engine assembly; an lubricant cooler, connected with said means for providing a flow of lubricant, to dissipate the heat carried by said lubricant from the internal combustion engine assembly prior to its return to internal combustion engine assembly; a turbofan assembly having a turbine connected with the means to carry the exhaust gas product of the combusted fuel-air mixture from the internal combustion engine assembly so that the exhaust gas carried from the internal combustion engine assembly drives the turbine, said turbofan assembly also having a ducted fan means driven by the turbine, said ducted fan means communicating with the atmosphere and generating a flow of cooling air; and means for directing the flow of cooling air generated by the ducted fan means through the lubricant cooler to cool the lubricant and dissipate the heat generated in operation of the internal combustion engine assembly.

2. The internal combustion engine system of claim 1 further comprising a motor-assisting said ducted fan means to supplement the exhaust gas energy at low idle and low engine speeds.

3. A method of providing cooling for an internal combustion engine, comprising:

-17- providing the internal combustion engine with a cooling flow of an engine lubricant; directing the exhaust gas from said engine to a turbine driving a ducted fan means; driving the turbine and ducted fan means with the exhaust gas of the internal combustion engine; generating a flow of air with said ducted fan means; directing the flow of air and the cooling flow of engine lubricant into a heat transfer relationship and cooling said engine lubricant with the flow of air from said turbocooler.

4. The method of claim 3 further comprising the step of assisting the turbine in generating a flow of air when said exhaust gas energy from the internal combustion engine assemblies is insufficient to maintain proper cooling of the internal combustion engine systems by using electrical energy in driving the ducted fan means.

5. The apparatus of claim 1 wherein said lubricant cooler is mounted upstream of said ducted fan and annular diffusers are mounted downstream of the ducted fan.

6. The apparatus of claim 1 wherein said lubricant cooler is mounted downstream of said ducted fan.

7. The method of claim 3 wherein said engine lubricant is a synthetic oil.

8. The method of claim 7 wherein said engine lubricant temperature is maintained in excess of about 300 degrees F. to lower lubricant viscosity and engine losses.

-18-

9. A motor-assisted cooling system for an internal combustion engine, comprising: an oil cooler connectable with a means for providing a flow of engine oil to dissipate the heat carried by said engine lubricant; and a turbofan assembly for generating a flow of cooling air, comprising a combined motor-turbine driving section and a ducted fan section sharing a common rotating shaft having a first end and a second end and a central portion carried by shaft bearings, said combined motor-turbine section comprising a plurality of turbine blades at said first end of said rotating shaft, an exhaust gas volute connectable with an internal combustion engine for directing exhaust gas from the internal combustion engine through said plurality of turbine blades to rotate said shaft, and an electric motor to assist said turbine in rotating said shaft, said electric motor including a plurality of magnets mounted on the central portion of said rotating shaft and a plurality of motor windings located around the periphery of the magnets, and said ducted fan section comprising a plurality of fan blades at said second end of said rotating shaft and a cooling air duct encompassing said fan blades, said flow of cooling air resulting from rotation of said rotating shaft by said motor-turbine driving section being directed into heat transfer relationship with the oil cooler.

10. The motor-assisted turbocooling assembly of claim 9 wherein said motor windings are in a heat transfer relationship with said cooling air duct.

11. The motor-assisted cooling system of claim 9 wherein said motor turbine driving section includes a bearing housing and said cooling air duct carries said plurality of motor windings and has an interior opening adjacent said plurality of motor windings and upstream of said fan blades, said

-19- bearing housing having an air inlet and providing an air passageway to said interior opening of said duct so rotation of said shaft and fan blades induces a cooling airflow through said bearing housing, said shaft bearings and motor windings.

12. The motor-assisted cooling system of claim 9 further comprising a turbocooling assembly including said oil cooler and said turbofan assembly, said turbocooling assembly further comprising means forming an air inlet for said ducted fan section and directing said flow of cooling air through said oil cooler, said oil cooler being upstream of said ducted fan.

13. The motor-assisted cooling system of claim 12 wherein said air inlet forming means surrounds and encloses said ducted fan section, carries a plurality of heat exchangers and directs said airflow through said plurality of heat exchangers.

14. The motor-assisted turbocooler assembly of claim 9 including means for mounting the motor-assisted turbocooler assembly on an engine driven vehicle.

15. The motor-assisted turbocooling assembly of claim 9 further comprising an electric motor control connectable with said plurality of motor windings to control application of electrical energy to said motor windings.

16. The motor-assisted turbocooling assembly of claim 15, further comprising an engine speed sensor for providing a signal for operation of said electric motor when said internal combustion engine operation provides insufficient exhaust gas energy for providing an acceptable flow of cooling air.

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17. The motor-assisted cooling system of claim 15 wherein said control further comprises an airflow sensor in the flow of cooling air to the oil cooler for providing an electric motor operating signal.

18. The internal combustion engine system of claim 15 wherein said control further comprises an engine speed sensor for providing an electric motor operating signal.

19. The internal combustion engine system of claim 15 wherein said control further comprises a sensor for engine exhaust gas pressure for providing an electric motor operating signal.

20. The internal combustion engine system of claim 15 wherein said control further comprises a temperature sensor for providing an electric motor operating signal.

21. A method of providing cooling for an internal combustion engine, comprising: providing the internal combustion engine with a cooling flow of engine lubricant; using the exhaust gas energy of the internal combustion engine for generating a flow of cooling air; directing the flows of engine lubricant and cooling air into a heat transfer relationship for cooling the engine lubricant; sensing at least one condition indicative of an inadequate flow of cooling air, and thereupon using electrical energy from said internal combustion engine for at least assisting the exhaust gas energy in the generation of the flow of cooling air.

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22. The method of claim 21 further comprising sensing engine speed of the internal combustion engine and using the electric energy for generation of the flow of cooling air where the engine speed is too low to provide an acceptable exhaust gas energy.

23. The method of claim 21 comprising sensing the temperature of the engine lubricant being cooled by said flow of cooling air and using the electric energy for generation of the flow of cooling air when the engine lubricant temperature is too high.

24. The method of claim 21 comprising sensing the flow of cooling air and using the electric energy for generation of the flow of cooling air when said cooling airflow is unacceptably low.

25. The method of claim 21 wherein the engine lubricant is a synthetic lubricant.

26. The method of claim 25 comprising sensing the temperature of the synthetic engine lubricant and controlling the electric energy and exhaust gas energy to maintain the temperature in excess about 300 degrees F. but below the degradation temperature of the synthetic engine lubricant.

27. A turbocooling assembly for an internal combustion engine, comprising a turbofan assembly comprising an exhaust gas turbine and a plurality of fan blades carried on a common shaft, said common shaft being rotatably supported by bearing means and by a bearing support, an exhaust gas volute for directing exhaust gas into said turbine and an air inlet means for said fan blades, wherein exhaust gas from an internal combustion engine rotates said turbine and fan blades creating a flow of air into said air inlet means,

-22- said air inlet means comprising a housing forming a chamber and enclosing said fan blades and carrying at least one air cooled heat exchanger in heat transfer relationship with said flow of air into said air inlet means.

28. The turbocooling assembly of claim 27 further comprising an annular diffuser downstream of said fan blades.

29. The turbocooling assembly of claim 28 wherein said housing carries said turbofan assembly and forms, in part, the annular diffusers downstream of the fan blades.

30. The turbocooling assembly of claim 27 wherein said at least one heat exchanger opens into the chamber so the flow of air is directed through the heat exchanger.

31. The turbocooling assembly of claim 27 wherein the turbofan assembly incorporates an electric motor with motor winding between the turbine and the fan blades, and the air inlet means is in heat transfer relationship with the motor windings.

32. The turbocooling assembly of claim 31 wherein the fan blades creates a flow of cooling air for the motor windings.

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