AU2009350143A1

AU2009350143A1 - Improving fuel efficiency for a piston engine using a super-turbocharger

Info

Publication number: AU2009350143A1
Application number: AU2009350143A
Authority: AU
Inventors: Volker Schumacher; Ed Vandyne
Original assignee: VanDyne SuperTurbo Inc
Current assignee: VanDyne SuperTurbo Inc
Priority date: 2009-07-24
Filing date: 2009-07-24
Publication date: 2012-02-02
Also published as: JP2013500422A; DE112009005092B4; GB2484234A; SE1250023A1; DE112009005092T5; CN102549248A; WO2011011019A1; GB201200713D0; CA2765902A1

Abstract

Disclosed is a system and method that increases the amount of power available from a super-turbocharger, and the fuel efficiency of an engine. The system utilizes a catalytic converter to provide thermal buffering to the turbine protecting it from thermal transients. Since the catalytic converter is exothermic, a portion of the compressed air generated by the compressor is fed back to the turbine via a feedback valve decreasing the exhaust temperature and increasing the mass flow provided to the turbine. The feedback valve can be used to reduce compressor surge during low rpm, high load conditions of said engine. The amount of compressor feedback air is limited to the amount of excess thermal energy so that an optimum turbine operating temperature of the combined engine exhaust gas and compressed air can be maintained. Excess power generated by the turbine is then used to drive the engine crank shaft.

Description

WO 2011/011019 PCT/US2009/051742 IMPROVING FUEL EFFICIENCY FOR A PISTON ENGINE USING A SUPER-TURBOCHARGER BACKGROUND OF THE INVENTION [00011 Increased power and fuel efficiency are of paramount importance for passenger and commercial vehicles. One method utilized to increase the power available from an engine is to utilize a turbocharger to increase the amount of air that can be supplied to the cylinders of the engine. With an increased amount of air, an increased amount of fuel can be utilized during each combustion event to thereby increase the power produced by the engine. BRIEF SUMMARY OF THE INVENTION [00021 An embodiment of the present invention may therefore comprise an engine system having high efficiency comprising: an engine; a super-turbocharger coupled to the engine so as to transfer rotational mechanical energy between a propulsion train and the super-turbocharger; a valve that regulates a flow of compressed air from the super turbocharger that is mixed with exhaust gases from the engine prior to the exhaust gases entering the super-turbocharger so that the compressed air cools the exhaust gases to a temperature that is below a predetermined maximum temperature to prevent damage to the super-turbocharger. [0003] An embodiment of the present invention may therefore further comprise a method of improving efficiency of an engine system comprising: coupling a super turbocharger to an engine; providing a flow of compressed air from the super-turbocharger to exhaust gases from the engine prior to the exhaust gases entering the super-turbocharger so that the compressed air cools the exhaust gases to a temperature which is below a predetermined maximum temperature to prevent damage to the super-turbocharger and provides additional mass to the exhaust gases entering the super-turbocharger. [00041 An embodiment of the present invention may therefore further comprise a super turbocharged engine system having high efficiency comprising: an engine; a super turbocharger comprising: a turbine that generates rotational mechanical energy from a gas mixture flowing through the turbine, a compressor that is mechanically coupled to the turbine that compresses a source of air and provides a supply of compressed air to an intake manifold of the engine; a transmission that is mechanically coupled to the turbine and the 1 WO 2011/011019 PCT/US2009/051742 compressor that transfers the turbines rotational mechanical energy from the turbine to a propulsion train to increase engine output power and prevent damage to the super turbocharger, and transfers propulsion train rotational mechanical energy from the propulsion train to the compressor to reduce turbo-lag of the engine; a feedback valve that regulates a portion of the compressed air that is mixed with the exhaust gases to create the gas mixture, the portion of the compressed air being sufficient to cool the exhaust gases below a predetermined maximum temperature to prevent damage to the turbine, as well as providing an additional mass of the air to the exhaust gases that adds additional rotational energy to the turbine. [0005] An embodiment of the present invention may therefore further comprise a method of improving efficiency of a super-turbocharged engine system comprising: providing compressed air from a compressor of a super-turbocharger; mixing a portion of the compressed air with exhaust gases from the engine to create a gas mixture having a temperature that does not exceed a predetermined maximum temperature to prevent damage to a turbine of said super-turbocharger; driving the turbine with the gas mixture; transferring excess turbine rotational mechanical energy from the turbine to a propulsion train that would otherwise cause the turbine to rotate at a speed which would cause damage to the compressor. [0006] An embodiment of the present invention may therefore further comprise a method of improving efficiency of a super-turbocharged engine system comprising: providing an engine; providing a catalytic converter that is connected to an exhaust outlet proximate to the engine that receives engine exhaust gases from the engine that activate an exothermic reaction in the catalytic converter which adds additional energy to the engine exhaust gases and produces catalytic converter exhaust gases at an output of the catalytic converter that are hotter than the engine exhaust gases; providing a flow of compressed air to an intake of the engine using a compressor; mixing a portion of the compressed air with the catalytic converter exhaust gases in a mixing chamber that is downstream from the catalytic converter to produce a gas mixture of the catalytic converter exhaust gases and the compressed air; regulating the flow of the compressed air into the mixing chamber using a control valve to maintain the gas mixture below a maximum temperature and to maintain a flow of the compressed air through the compressor during operational phases of the engine when surge in the compressor would otherwise occur; supplying the gas mixture to a turbine that produces rotational mechanical energy in response to flow of the gas mixture; transmitting the turbines rotational mechanical energy from the turbine to the compressor that uses the rotational energy to compress a source of air to produce the compressed air 2 WO 2011/011019 PCT/US2009/051742 when the flow of the gas mixture through the turbine is sufficient to drive the compressor; extracting at least a portion of the turbines rotational mechanical energy from the turbine and applying that portion of the turbines rotational mechanical energy to a propulsion train when that portion of the turbines rotational mechanical energy from the turbine is not needed to run the compressor; providing propulsion train rotational mechanical energy from the propulsion train to the compressor to prevent turbo-lag when the flow of the gas mixture through the turbine is not sufficient to drive the compressor. [0007] An embodiment of the present invention may therefore further comprise a super turbocharged engine comprising: an engine; a catalytic converter connected to an exhaust conduit proximate to an exhaust outlet of the engine such that hot exhaust gases from the engine activate an exothermic reaction in the catalytic converter that adds energy to the hot exhaust gases and produces hotter exhaust gases; a compressor connected to a source of air that provides compressed air that has a pressure that is greater than a pressure level of the exhaust gases; a conduit that supplies the compressed air to the hotter exhaust gases so that at least a portion of the compressed air is mixed with the hotter exhaust gases to produce a gas mixture; a valve that regulates flow of the portion of the compressed air through the conduit to maintain the gas mixture below a predetermined maximum temperature and to maintain a flow of air from the source of air through the compressor during operational phases of the engine when surge in the compressor would otherwise occur; a transmission that provides propulsion train rotational mechanical energy from a propulsion train to the compressor to reduce turbo-lag when the flow of the exhaust through the turbine is not sufficient to drive the compressor to a desired boost level, and extracts excess turbine rotational mechanical energy from the turbine to maintain rotational speeds of the compressor below a predetermined maximum rotational speed at which damage would occur to the compressor. BRIEF DESCRIPTION OF THE DRAWINGS [0008] Figurel is a simplified single line system diagram of one embodiment of a super-turbocharger engine in accordance with the teachings of the present invention. [0009] Figure 2 is a schematic illustration of an implementation of the embodiment of Figure 1. 3 WO 2011/011019 PCT/US2009/051742 DETAILED DESCRIPTION OF THE INVENTION [00101 Figure 1 is simplified single line form an illustration of one embodiment of a high efficiency, super-turbocharged engine system 100 constructed in accordance with the teachings of the present invention. As will become apparent to those skilled in the art from the following description, such a super-turbocharged engine system 100 finds particular applicability in spark ignited, gasoline engines that are used in passenger and commercial vehicles, and therefore the illustrative examples discussed herein utilize such an environment to aid in the understanding of the invention. However, recognizing that embodiments of system 100 of the present invention have applicability to other operating environments such as, for example, land based, power generation engines, and other land based engines, such examples should be taken by way of illustration and not by way of limitation. [0011] As may be seen from FIG. 1, the system 100 includes an engine 102 that utilizes a super-turbocharger 104 to increase the performance of the engine 102. In general, a super-turbocharger comprises a compressor and a turbine that are coupled together with a turbo shaft. Other ways to couple the compressor and turbine together have been used. Further, the super-turbocharger includes a transmission which transmits power between the turbo shaft and the power train or drive train (propulsion train) of the vehicle. For example, the transmission may be mechanically coupled to the crank shaft of an engine or to the vehicle's transmission, or other portions of the drive train or power train. These are collectively referred to as the propulsion train of the vehicle. The transmission can be a mechanical transmission that uses gearing, a hydraulic transmission, pneumatic transmission, a traction drive transmission or an electrical transmission. An electric motor/generator can be coupled to the turbo shaft and used to either drive the turbo shaft or be driven by the turbo shaft and generate electrical energy. The electrical energy generated by the motor/generator can be used to charge batteries, drive motor/generators that are used to drive the vehicle, or assist in powering the vehicle in hybrid cars. In that regard, the super-turbocharged engine system 100 may be sized and used for the purposes of generating electricity in an electric car system, or may be employed to both generate energy and assist in powering the vehicle with mechanical energy, such as in a hybrid vehicle system. 10012] As shown in Figure 1, the super-turbocharger 104 includes a turbine 106, a compressor 108, and a transmission 110 that is coupled to the crank shaft 112 of the engine 102 or other portions of the propulsion train. While not required in all embodiments, the illustrated embodiment of FIG. I also includes an intercooler 114 to increase the density of 4 WO 2011/011019 PCT/US2009/051742 the air supplied to the engine 102 from the compressor 108 to further increase the power available from the engine 102. [0013] Super-turbochargers have certain advantages of turbochargers. A turbocharger utilizes a turbine that is driven by the exhaust of the engine. This turbine is coupled to a compressor which compresses the intake air that is fed into the cylinders of the engine. The turbine in a turbocharger is driven by the exhaust from the engine. As such, the engine experiences a lag in boost when first accelerated until there is enough hot exhaust to spin up the turbine to power a compressor, which is mechanically coupled to the turbine, to generate sufficient boost. To minimize lag, smaller and/or lighter turbochargers are typically utilized. The lower inertia of the lightweight turbochargers allows them to spin up very quickly, thereby minimizing the lag in performance. [0014] Unfortunately, such smaller and/or lighter weight turbochargers may be over sped during high engine speed operation when a great deal of exhaust flow and temperature is produced. To prevent such over speed occurrences, typical turbochargers include a waste gate valve that is installed in the exhaust pipe upstream of the turbine. The waste gate valve is a pressure operated valve that diverts some of the exhaust gas around the turbine when the output pressure of the compressor exceeds a predetermined limit. This limit is set at a pressure that indicates that the turbocharger is about to be over-sped. Unfortunately, this results in a portion of the energy available from the exhaust gases of the engine being wasted. [0015] Recognizing that conventional turbochargers sacrifice low end performance for high end power, devices known as super-turbochargers were developed. One such super turbocharger is described in US Patent No. 7,490,594 entitled "Super-Turbocharger," issued February 17, 2009, and assigned to the assignee of the instant application. This application is specifically incorporated herein by reference for all that it discloses and teaches. [0016] As discussed in the above-referenced application, in a super-turbocharger the compressor is driven by the engine crank shaft via a transmission that is coupled to the engine during low engine speed operation when sufficiently heated engine exhaust gas is not available to drive the turbine. The mechanical energy supplied by the engine to the compressor reduces the turbo lag problem suffered by conventional turbochargers, and allows for a larger or more efficient turbine and compressor to be used. 5 WO 2011/011019 PCT/US2009/051742 [0017] The super-turbocharger 104, illustrated in Figure 1, operates to supply compressed air from the compressor 108 to the engine 102 without suffering from the turbo lag problem of a conventional turbocharger at the low end and without wasting energy available from the engine exhaust gas heat supplied to the turbine 106 at the high end. These advantages are provided by inclusion of the transmission 110 that can both extract power from, and supply power to, the engine crank shaft 112 to both drive the compressor 108 and load the turbine 106, respectfully, during various modes of operation of the engine 102. [0018] During start up, when conventional turbochargers suffer a lag due to the lack of sufficient power from the engine exhaust heat to drive the turbine, the super-turbocharger 104 provides a supercharging action whereby power is taken from the crank shaft 112 via the transmission 110 to drive the compressor 108 to provide sufficient boost to the engine 102. As the engine comes up to speed and the amount of power available from the engine exhaust gas heat is sufficient to drive the turbine 106, the amount of power taken from the crank shaft 112 by the transmission 110 is reduced. Thereafter, the turbine 106 continues to supply power to the compressor 108 to compress the intake air for use by the engine 102. [00191 As the engine speed increases, the amount of power available from the engine exhaust gas heat increases to the point where the turbine 106 would over speed in a conventional turbocharger. However, with the super-turbocharger 104, the excess energy provided by the engine exhaust gas heat to the turbine 106 is channeled through the transmission 110 to the engine crank shaft 112 while maintaining the compressor 108 at the proper speed to supply the ideal boost to the engine 102. The greater the output power available from the exhaust gas heat of the engine 102, the more power generated by the turbine 106 that is channeled through the transmission 110 to the crank shaft 112 while maintaining the optimum boost available from the compressor 108. This loading of the turbine 106 by the transmission 110 prevents the turbine 106 from over speeding and maximizes the efficiency of the power extracted from the engines exhaust gases. As such, a conventional waste gate is not required. [0020] While the amount of power available to drive the turbine 106 in a conventional super-turbocharged application is limited strictly to the amount of power available from the engine exhaust, the turbine 106 is capable of generating significantly more power if the thermal energy and mass flow supplied to the turbine blades can be fully utilized and/or can be increased. However, the turbine 106 cannot operate above a certain temperature without 6 WO 2011/011019 PCT/US2009/051742 damage, and the mass flow is conventionally limited to the exhaust gases coming out of the engine 102. [0021] Recognizing this, the embodiment of the system 100 protects the turbine 106 from high temperature transients by relocating the catalytic converter 116 upstream of the turbine 106. In one embodiment, the catalytic converter is placed upstream from the turbine near the exhaust manifold which enables exothermic reactions that result in an increase in exhaust gas temperature during sustained high speed or load operation of the engine. To cool the exhaust gas, prior to reaching the turbine, a portion of the compressed air generated by the compressor is fed directly into the exhaust upstream from the turbine via a controllable valve and added to the engine exhaust gases leaving the catalytic converter. The cooler intake air expands and cools the exhaust gas and adds additional mass to the exhaust gas flow, which adds additional power to the turbine of the super-turbocharger as described in more detail below. As more cooler air is provided to the hot exhaust gases to maintain the temperature of the combined flow to the turbine at the optimum temperature, the energy and the mass flow that is delivered to the turbine blades also increases. This significantly increases the power supplied by the turbine to drive the engine crank shaft. [00221 So as to not interfere with the stoichiometric reaction within the catalytic converter, the compressor feedback air is added downstream of the catalytic converter. In such an embodiment, the engine exhaust gas is passed through the catalytic converter and temperature of the exhaust gas is increased by the exothermic reaction. The compressor feedback air is then added and expands so that the total mass flow supplied to the turbine is increased. Embodiments of the present invention control the amount of compressed feedback air supplied to cool the exhaust and to drive the turbine to ensure that the combination of the cooler compressor feedback air and the engine exhaust gases are delivered to the turbine at an optimum temperature for turbine blade operation. [00231 Since the catalytic converter 116, illustrated in Figure 1, has a large thermal mass, it operates as a thermal damper initially, which prevents a high temperature thermal spike from reaching the turbine 106. However, since the reactions in the catalytic converter 116 are exothermic in nature, the temperature of the exhaust gases leaving the catalytic converter 116 will eventually be higher than that of the exhaust gas entering the catalytic converter 116. So long as the temperature of the exhaust gas entering the turbine remains below the maximum operating temperature of the turbine 106, there is no problem. 7 WO 2011/011019 PCT/US2009/051742 [00241 However, during sustained high speed and high load operation of the engine 102, the exit temperatures of the converted exhaust gas from catalytic converter 116 can exceed the maximum operating temperature of turbine 106. As set forth above, the temperature of the exhaust gases exiting the catalytic converter 116 are reduced by supplying a portion of the compressed air from the compressor 108 via a feedback valve 118, and mixed with the exhaust gas exiting the catalytic converter 116. Significantly improved fuel economy is achieved by not using fuel as a coolant during such conditions, as is done in conventional systems. Additionally, the operation of the transmission is controlled to allow the compressor 108 to supply a sufficient amount of compressed air to provide optimum boost to the engine 102 and the compressed feedback air to the turbine 106 via the feedback valve 118. The excess power generated by the turbine 106 resulting from the increased mass flow of the compressed air through the turbine is channeled via the transmission 110 to the crank shaft 112, yet further increasing fuel efficiency. [0025] The output temperature of the compressed air from the compressor 108 is typically between about 200'C to 300'C. A conventional turbine can operate optimally to extract power from gases at approximately 950'C, but not higher without distortion or possible failure. Because of the material limits of the turbine blades the optimal power is achieved at approximately 950'C. Since the materials limit the exhaust gas temperatures to about 950'C, supplying more air to increase the mass flow across the turbine at the temperature limit, e.g., 950'C, increases the performance of the turbine. [0026] While such a flow of compressed feedback air at 200'C to 300'C is helpful in reducing the temperature of the exhaust gas coming out of the catalytic converter 116, it is recognized that maximum power from the turbine 106 can be supplied when the temperature and the mass flow is maximized within the thermal limits of the turbine 106. As such, in one embodiment, the amount of feedback air is controlled so that the combination of exhaust gas and feedback air is maintained at or near the turbine's maximum operating temperature so that the amount of power delivered to the turbine is maximized or significantly increased. Since all of this excess power is normally not required by the compressor 108 to supply the optimum boost to engine 102 and to supply the compressor feedback air via feedback valve 118, the excess power may be transferred by the transmission 110 to the crank shaft 112 of the engine 102 to thereby increase the overall efficiency or power of the engine 102. [00271 As discussed above, in one embodiment, the connection of the compressor feedback air via feedback valve 118 employs a catalytic converter 116 as the thermal buffer 8 WO 2011/011019 PCT/US2009/051742 between the engine 102 and turbine 106. As such, the supply of air from the compressor is provided downstream of the catalytic converter 116 so as to not disrupt the stoichiometric reaction within the catalytic converter 116. That is, in embodiments that utilize a catalytic converter 116, supplying the compressor feedback air upstream of the catalytic converter 116 would result in excess oxygen being supplied to the catalytic converter 116, thereby preventing the catalytic converter 116 from generating a stoichiometric reaction that is required for proper operation. [0028] Since optimum efficiency of power generation by the turbine 106 is achieved when the temperature of the gas mixture of the compressor feedback air and exhaust gas on the turbine blades is maximized (within the material limits of the turbine itself), the amount of compressor feedback air admitted by the feedback valve 118 is limited so as to not reduce the temperature significantly below such an optimized temperature. As the catalytic converter 116 produces more thermal energy via an exothermic reaction and the temperature of the converted exhaust gases from the catalytic converter 116 increases to a temperature above the maximum operating temperature of the turbine 106, more compressor feedback air may be supplied via feedback valve 118 which increases the mass flow and energy supplied to the turbine 106. As the amount of thermal energy generated by catalytic converter 116 is reduced, the amount of compressor feedback air supplied by feedback valve 118 can also be reduced so as to avoid supplying more air than necessary, which results in the maintenance of the temperature of the gas mixture at the optimum operating condition. [0029] In another embodiment, the system utilizes the feedback valve 118 for feeding back the cooler compressor air into the exhaust ahead of the turbine at low speed, high load operating conditions to avoid surging the compressor. Compressor surge occurs when the compressor pressure gets high but the mass flow allowed into the engine is low as a result of the engine from turning at a slow rpm and not requiring much intake air flow. Surging (or aerodynamic stalling) of the compressor resulting from low airflow across the compressor blades causes the efficiency of the compressor to fall very rapidly. In the case of a normal turbocharger, enough surge can stop the turbine from spinning. In the case of a super turbocharger it is possible to use power from the engine crank shaft to push the compressor into surge. Opening the feedback valve 118 allows a portion of the compressed air to feedback around the engine. This feedback flow brings the compressor out of surge and allows higher boost pressure to reach the engine 102, thereby allowing the engine 102 to generate more power than would normally be possible at low engine speeds. Injecting the compressed air into the exhaust ahead of the turbine conserves the total mass flow through 9 WO 2011/011019 PCT/US2009/051742 the compressor so that all the flow reaches the turbine which minimizes the power needed from the engine to supercharge to a high boost pressure level. [0030] In another embodiment, an additional cold start control valve 120 may be included for operation during rich engine cold starts. During such an engine cold start, the exhaust gases from the engine 102 typically include excess un-burnt fuel. Since this rich mixture is not stoichiometric, the catalytic converter 116 is unable to fully reduce the un burnt hydrocarbons (UHC) in the exhaust gas. During such times, the cold start control valve 120 may be opened to provide compressor feedback air to the input of the catalytic converter 116 to supply the extra oxygen necessary to bring the rich mixture down to stoichiometric levels. This allows the catalytic converter 116 to light off faster and more efficiently reduce the emissions during the cold start event. If the engine is idling, a normal turbocharger would have no boost pressure to be able to supply the feedback air. However, the transmission ratio of transmission 110 can be adjusted to give enough speed to the compressor to generate the pressure needed for the air to flow through valve 120. In that regard, control signal 124 can be used to adjust the ratio of transmission 110 so that sufficient rotational speed can be provided from the engine drive shaft 112 to the compressor 108 during idling, especially during a cold start, to compress enough air to flow through the cold start valve 120 and ignite catalytic converter 116 with a sufficient amount of oxygen. [0031] The requirement for the additional oxygen is typically limited in a cold start event, and often lasts only for 30 to 40 seconds. Many vehicles currently include a separate air pump to supply this oxygen during the cold start event, at significant cost and weight compared to the limited amount of time that such an air pump is required to operate. By replacing the separate air pump with the simple cold start control valve 120, significant costs, weight and complexity savings are realized. Because the super-turbocharger 104 can control the speed of the compressor 108 via the transmission 110, the cold start control valve 120 may comprise a simple on off valve. The amount of air supplied during the cold start event can then be controlled by controlling the speed of the compressor 108 via transmission 110 under operation of the control signal 124. [0032] The cold start control valve 120 may also be used during periods of extremely high temperature operation if fuel is used as a coolant within the engine and/or for the catalytic converter 116, despite the negative effect on fuel efficiency. In such situations, the cold start control valve 120 will be able to supply the extra oxygen necessary to bring the rich exhaust back down to stoichiometric levels to allow the catalytic converter 116 to 10 WO 2011/011019 PCT/US2009/051742 properly reduce the unburned hydrocarbon emissions in the exhaust. This provides a significant benefit to the environment over prior systems. [0033] In embodiments where the cold start control valve 120 is an on/off valve, the system can modulate cold start control valve 120 to vary the amount of compressed air supplied so as to bring the exhaust down to stoichiometric levels. Other types of variable flow control valves may also be used to accomplish this same function. [0034] Figure 1 also discloses a controller 140. Controller 140 controls the operation of the feedback valve 118 and the cold start valve 120. Controller 140 operates to optimize the amount of air flow through feedback valve 118 for different conditions. The amount of air that flows through the feedback valve 118 is the minimal amount of air flow that is necessary to obtain a specific desired condition, as described above. There are two specific conditions in which controller 140 operates feedback valve 118, which are: 1) surge limit of the compressor for a given boost requirement is proximate at low rpm, high load of the engine; and, 2) temperature of the gas mixture is proximate entering the turbine 106 at high rpm, high load conditions. [00351 As shown in Figure 1, controller 140 receives the gas mixture temperature signal 130 from a temperature sensor 138 that detects the temperature of the gas mixture of the cooling air supplied from the compressor 108 that is mixed with the hot exhaust gases produced by the catalytic converter 116. In addition, the controller 140 detects the compressed air intake pressure signal 132 that is generated by the pressure sensor 136 that is disposed in the conduit of compressed air that is supplied from the compressor 108. Further, an engine speed signal 126 and an engine load signal 128 that are supplied from the engine 102 or a throttle are fed to the controller 140 . [0036] With respect to control of the temperature of the gas mixture that is supplied to the turbine 106 at high speed, high load conditions, controller 140 limits the temperature of the gas mixture to a temperature that maximizes the operation of the turbine 106, without being so high as to damage the mechanisms of the turbine 106. In one embodiment, a temperature of approximately 925'C is an optimal temperature for the gas mixture to operate the turbine 106. Once the temperature of the gas mixture that is fed into the turbine 106 begins to exceed 900'C, the feedback valve 118 is opened, to allow compressed air from the compressor 108 to cool the hot exhaust gases from the catalytic converter 116 prior to passing into the turbine 106. The controller 140 can be designed to target a temperature of approximately 925'C, with an upper bound of 950'C and a lower bound of 900'C. The 11 WO 2011/011019 PCT/US2009/051742 limit of 950'C is one at which damage to the turbine 106 may occur using conventional materials. Of course, the controller can be designed for other temperatures, depending upon the particular types of components and materials used in the turbine 106. A conventional proportional integral derivative (PID) control logic device can be used in the controller 140 to produce these controlled results. [00371 The benefit of controlling the temperature of the gas mixture that enters the turbine 106 is that the use of fuel in the exhaust to limit the turbine inlet temperatures of the gas mixture is eliminated. Using the flow of the cooler compressed air to cool the hot exhaust gases from the catalytic converter 116 requires a large amount of air, which contains a large mass to achieve the desired cooler temperatures of the gas mixture. The amount of air that is required to cool the hot exhaust gases from the catalytic converter 116 is large because the cooler compressed air from the compressor 1.08 is not a good coolant, especially when compared to liquid fuel that is inserted in the exhaust gas. The hot exhaust gases from the output of the catalytic converter 116 cause the cooler compressed gas from the compressor 108 to expand to create the gas mixture. Since a large mass of the cooler compressed air from the compressor 108 is required to lower the temperature of the hot exhaust gases from the catalytic converter 116, a large mass flow of the gas mixture flows across the turbine 106, which greatly increases the output of the turbine 106. The turbine power increases by the difference of the power created by the differential of the mass flow minus the work required to compress the compressed air flowing through the feedback valve 118. By obtaining the gas mixture temperature signal 130 from temperature sensor 138 and controlling the addition of compressed air by feedback valve 118, the maximum temperature is not exceeded. [0038] Controller 140 also controls the feedback valve 118 to limit surge in the compressor 108. The surge limit is a boundary that varies as a function of the boost pressure, the flow of air through the compressor and the design of the compressor 108. Compressors, such as compressor 108, that are typically used in turbochargers, exceed a surge limit when the flow of intake air 122 is low and the pressure ratio between the intake air 122 and the compressed air is high. In conventional super-turbochargers, the flow of intake air 122 is low when the engine speed (rpm) 126 is low. At low rpms, when the compressed air is not used in large volumes by the engine 102, the mass flow of intake air 122 is low and surge occurs because the rotating compressor 108 cannot push air into a high pressure conduit without a reasonable flow of intake air 122. The feedback valve 118 allows flow through the compressed air conduit 109 and prevents or reduces surge in the compressor 108. Once surge in the compressor 108 occurs, the pressure in the compressed 12 WO 2011/011019 PCT/US2009/051742 air conduit 109 cannot be maintained. Hence, at low rpm, high load operating conditions of the engine 102, the pressure of the compressed air in the compressed air conduit 109 may drop below desired levels. By opening the feedback valve 118, the flow of intake air 122 through the compressor 108 is increased, especially at low rpm, high load operating conditions of the engine, which allows the desired level of boost to be achieved in the compressed air conduit 109. Feedback valve 118 can simply be opened until the desired pressure in the compressed air conduit 109 is reached. However, by simply detecting boost pressure in the compressed air conduit 109, surge will occur prior to the feedback valve 118 being opened to bring the compressor 108 out of a surge condition. [0039] It is preferable, however, to determine a surge limit and open the feedback valve 118 in advance, prior to the occurrence of a surge condition. For a given rpm and desired boost level a surge limit can be determined. The feedback valve 118 can begin to open prior to the compressor 108 reaching a calculated surge limit. Opening the valve early allows the compressor to spool up to a higher boost pressure more quickly because the compressor stays closer to the higher efficiency points of the compressor operational parameters. Rapid boost pressure rise at low rpm can then be achieved. By opening the valve before surge occurs, a more stable control system can also be achieved. [0040] Opening the feedback valve 118 in such a way as to improve the responsiveness of the engine 102, is achieved by allowing the engine 102 to get to a higher boost pressure more quickly when the engine 102 is at a lower rpm. Compressor 108 is also more efficient, which results in less work for the transmission 110 to achieve supercharging. Surge limit control can be modeled within standard model based control simulation code, such as MATLAB. Modeling in this manner will allow simulation of the controller 140 and auto-coding of algorithms for controller 140. [00411 A model based control system, such as described above, is unique, in that the utilization of the transmission 110 to control the rotation of the turbine 106 and compressor 108 generates boost pressure without turbo lag. In other words, the transmission 110 can extract rotational energy from the crank shaft 112 to drive the compressor 108 to achieve a desired boost in compressed air conduit 109 very quickly and prior to the turbine 106 generating sufficient mechanical energy to drive the compressor 108 at such a desired level. In this manner, controls in a conventional turbocharger to reduce lag are reduced or eliminated. The model based control of the controller 140 should be designed to maintain the optimum efficiency of the compressor 108 within the operational parameters of the compressor 108. 13 WO 2011/011019 PCT/US2009/051742 [0042] The control model of controller 140 should also be carefully modeled on the pressure operational parameters, as mapped against the mass flow allowed by the engine for a given target speed and load in which target speed and load may be defined relative to the position of the throttle of the vehicle. As shown in Figure 1, the engine speed signal 126 can be obtained from engine 102 and is applied to the controller 140. Similarly, the engine load signal 128 can be obtained from the engine 102 and applied to controller 140. Alternatively, these parameters can be obtained from a sensors located on the engine throttle (not shown). The feedback valve 118 can then be operated in response to a control signal 142 generated by controller 140. Pressure sensor 136 generates the compressed air intake pressure signal 132 that is applied to the controller 140, which calculates the control signal 142 in response to engine speed signal 126, engine load signal 128 and compressed air intake pressure signal 132. [00431 During operational conditions of the engine 102, in which a surge limit is not being approached by the compressor 108 and the temperature of the gas mixture, as detected by the temperature sensor 138, is not reached, the feedback valve 118 is closed so that the system works as a conventional super-turbocharged system. This occurs over a majority of the operating parameters of the engine 102. When high load and low rpm conditions of the engine 102 occur, the feedback valve 118 is opened to prevent surge. Similarly, at high rpm, high load operating conditions of engine 102, high temperatures are produced in the exhaust gases at the output of the catalytic converter 116, so that the feedback valve 118 must be opened to reduce the temperature of the gas mixture applied to the turbine 106 below a temperature which would cause damage to the turbine 106. [00441 Figure 2 is a detailed diagram of the embodiment of the high efficiency super turbocharged engine system illustrated in Figure 1. As shown in Figure 2, engine 102 includes a super-turbocharger that has been modified, as described above with respect to Figure 1, to provide overall higher efficiency than conventional super-turbocharged engines, as well as providing high, optimal efficiency in low rpm, high load operating conditions, and high, optimal efficiency at high rpm, high load conditions. The super-turbocharger includes a turbine 106 that is mechanically connected by a shaft to compressor 108. Compressor 108 compresses intake air 122 and supplies the compressed intake air to conduit 204. Conduit 204 is connected to feedback valve 118 and intercooler 114. As disclosed above, intercooler 114 functions to cool the compressed air, which becomes heated during the compression process. The intercooler 114 is connected to the compressed air conduit 226 which, in turn, is connected to the intake manifold (not shown) of the engine 102. Pressure sensor 136 is connected to the compressed air conduit 204 to detect the 14 WO 2011/011019 PCT/US2009/051742 pressure and supply a pressure reading via the compressed intake air pressure signal 132, which is applied to controller 140. The feedback valve 118 is controlled by a controller feedback valve control signal 142 generated by the controller 140, as disclosed above. Under certain operating conditions, feedback valve 118 opens to supply compressed air from compressed air conduit 204 to a mixing chamber 206. [0045] As shown in the embodiment of Figure 2, the mixing chamber 206 simply comprises a series of openings 202 in the catalytic converter output conduit 208, which is surrounded by the compressed air conduit 204 so that compressed air supplied from the compressed air conduit 204 passes through the openings 202 to mix with the exhaust gases in the catalytic converter output conduit 208. Any desired type of mixing chamber can be used to mix the cooler compressed air with the exhaust gases to lower the temperature of the exhaust gases. Temperature sensor 138 is located in the catalytic converter output conduit 208 to measure the temperature of the exhaust gases in the catalytic converter output conduit 208. Temperature sensor 138 supplies a gas mixture temperature signal 130 to controller 140, which controls the feedback valve 118 to ensure that the temperature of the exhaust gases in the catalytic converter output conduit 208 do not exceed a maximum temperature that would damage to the turbine 106. Catalytic converter 116 is connected to the exhaust manifold 210 by way of catalytic converter inlet conduit 214. By locating the catalytic converter 116 proximate to the exhaust manifold 210, the hot exhaust gases from the engine flow directly into the catalytic converter 116, which assists in activating the catalytic converter 116. In other words, the proximate location of the catalytic converter 116 near the outlet of the engine exhaust gases does not allow the exhaust gases to cool substantially prior to entering the catalytic converter 116, which increases the performance of the catalytic converter 116. As the exhaust gases pass through the catalytic converter 116, the catalytic converter 116 adds additional heat to the exhaust gases. These very hot exhaust gases at the output of the catalytic converter 116 are supplied to the catalytic converter output conduit 208 and are cooled in the mixing chamber 206 with the compressed intake air from the compressed air conduit 204. Depending upon the temperature of the very hot exhaust gases that are produced at the output of the catalytic converter 116, which varies depending upon the operating conditions of the engine 102, a different amount of compressed intake air will be added to the exhaust gas during high speed, high load conditions. During low engine speed, high engine load conditions, the feedback valve 118 also functions to allow intake air to flow through the compressor to avoid surge. Surge is similar to aerodynamic stall of the compressor blades, which occurs as a result of the low flow conditions through the compressor during low engine speed conditions. When surge occurs, the pressure in the intake manifold (not shown) falls 15 WO 2011/011019 PCT/US2009/051742 because the compressor 108 is unable to compress the intake air. By allowing air to flow through the compressor 108 as a result of the feedback valve 118 being opened, pressure can be maintained in the intake manifold so that, when high torque is required at low engine speeds, the high torque can be achieved because of the high intake manifold pressure. [0046] As disclosed above, when the engine is operating under high speed, high load conditions, the catalytic converter 116 causes a large amount of heat to be generated in the exhaust gases that are supplied to the catalytic converter output conduit 208. By supplying compressed, cooler intake air to the catalytic converter output conduit 208, the hot exhaust gases under high speed, high load conditions are cooled. As the load and speed of the engine increases, hotter gases are produced and more of the compressed air from conduit 204 is required. If the turbine 106 does not provide sufficient rotational energy to drive the compressor, such as under low speed, high load conditions, the engine crank shaft 112 can supply rotational energy to the compressor 108 via drive belt 222, drive pulley 218, shaft 224, continuously variable transmission 216 and transmission 228. Again, any portion of the propulsion train can be used to supply rotational energy to the compressor 108, and Figure 2 discloses one implementation in accordance with one disclosed embodiment. [0047] As also illustrated in Figure 2, a cold start valve 120 is also connected to the compressed air conduit 204, which in turn is connected to the cold start conduit 212. Cold start conduit 212 is connected to the catalytic converter inlet conduit 214, which is upstream from the catalytic converter 116. The purpose of the cold start valve is to provide compressed intake air to the input of the catalytic converter 116 during startup conditions, as disclosed above. Under startup conditions, prior to the catalytic converter 116 reaching full operational temperatures, additional oxygen is provided via the cold start conduit 212 to initiate the catalytic process. The additional oxygen that is provided via the cold start conduit 212 assists in the initiation of the catalytic process. Controller 140 controls cold start valve 120 via controller cold start valve control signal 144 in response to the engine speed signal 126, engine load signal 128, and the gas mixture temperature signal 130. 10048] Hence, the high efficiency, spark ignition, super-turbocharged engine 100 operates in a manner similar to a super-turbocharger, with the exception that feedback valve 118 supplies a portion of the compressed air from the compressor to the input of the turbine for two reasons. One reason is to cool the exhaust gases prior to entering the turbine so that the full energy of the exhaust gases can be utilized and a waste gate is not needed under high speed, high load conditions. The other reason is to provide a flow of air through the compressor to prevent surge at low rpm, high load conditions. In addition, the catalytic 16 WO 2011/011019 PCT/US2009/051742 converter can be connected in the exhaust stream before the exhaust gases reach the turbine so that the heat generated by the catalytic converter 116 can be used in driving the turbine 106, and expanding the compressed intake air that is mixed with the hot gases from the catalytic converter 116, which greatly increases efficiency of the system. Further, the cold start valve 120 can be used to initiate the catalytic process in the catalytic converter 116 by providing oxygen to the exhaust gases during startup conditions. [0049] The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art. 17

Claims

1. An engine system having high efficiency comprising: an engine; a super-turbocharger coupled to said engine so as to transfer rotational mechanical energy between a propulsion train and said super-turbocharger; a valve that regulates a flow of compressed air from said super-turbocharger that is mixed with exhaust gases from said engine prior to said exhaust gases entering said super-turbocharger so that said compressed air cools said exhaust gases to a temperature that is below a predetermined maximum temperature to prevent damage to said super-turbocharger.

2. The engine system of claim 1 further comprising: a catalytic converter connected to said engine that receives said exhaust gases from said engine prior to said exhaust gases entering said super-turbocharger.

3. The engine system of claim 2 wherein said super-turbocharger further comprises: a mechanical transmission that transfers super-turbocharger rotational mechanical energy from said super-turbocharger to a propulsion train to increase said efficiency of said engine system and extract excess energy from said super turbocharger to prevent damage to said super-turbocharger, and transfers propulsion train rotational mechanical energy from said propulsion train to said super turbocharger to reduce turbo-lag. 18 WO 2011/011019 PCT/US2009/051742

4. The engine system of claim 3 wherein said valve also maintains a flow of air through said super-turbocharger to reduce surge in said super-turbocharger.

5. The engine system of claim 4 further comprising: a controller that receives operational parameters of said engine and generates control signals that control operation of said valve.

6. The engine system of claim 5 further comprising: an exhaust conduit that is operatively coupled to a compressed air conduit that receives said flow of said compressed air.

7. A method of improving efficiency of an engine system comprising: coupling a super-turbocharger to an engine; providing a flow of compressed air from said super-turbocharger to exhaust gases from said engine prior to said exhaust gases entering said super-turbocharger so that said compressed air cools said exhaust gases to a temperature which is below a predetermined maximum temperature to prevent damage to said super turbocharger and provides additional mass to said exhaust gases entering said super turbocharger.

8. The method of claim 7 further comprising: connecting a catalytic converter between said engine and said super turbocharger so that said exhaust gases from said engine flow through said catalytic converter prior to entering said super-turbocharger.

9. The method of claim 7 further comprising: coupling super-turbocharger rotational mechanical energy from said super turbocharger to a propulsion train to increase efficiency of said engine and prevent damage to said super-turbocharger. 19 WO 2011/011019 PCT/US2009/051742

10. The method of claim 9 further comprising: reducing turbo-lag in said super-turbocharger by transferring propulsion train rotational mechanical energy from a propulsion train to said super-turbocharger.

11. The method of claim 9 further comprising: maintaining a flow of air through said super-turbocharger to reduce surge of said super-turbocharger during operational phases of said engine when compressor surge would otherwise occur.

12. A super-turbocharged engine system having high efficiency comprising: an engine; a super-turbocharger comprising: a turbine that generates turbine rotational mechanical energy from a gas mixture flowing through said turbine; a compressor that is mechanically coupled to said turbine that compresses a source of air and provides a supply of compressed air to an intake manifold of said engine; a transmission that is mechanically coupled to said turbine and said compressor that transfers said turbine rotational mechanical energy from said turbine to a propulsion train to increase engine output power and prevent damage to said super-turbocharger, and transfers propulsion train rotational mechanical energy from said propulsion train to said compressor to reduce turbo-lag of said engine; a feedback valve that supplies a portion of said compressed air that is mixed with said exhaust gases to create said gas mixture, said portion of said compressed air being sufficient to cool said exhaust gases below a 20 WO 2011/011019 PCT/US2009/051742 predetermined maximum temperature to prevent damage to said turbine, as well as providing an additional mass of said air to said exhaust gases that adds additional rotational energy to said turbine.

13. The engine system of claim 12 wherein said valve additionally maintains a flow of said air through said compressor during operational phases of said engine when compressor surge would otherwise occur.

14. The engine system of claim 13 further comprising: a catalytic converter disposed to receive said exhaust gases from said engine that produces an exothermic reaction that adds heat to said exhaust gases that are supplied to said turbine to drive said turbine.

15. The engine system of claim 14 further comprising: a cold start control valve that provides a portion of said compressed air to an input of said catalytic converter to add oxygen to said exhaust gases that assist said catalytic converter in initiating an exothermic reaction.

16. The engine system of claim 15 further comprising: a controller that operates said feedback valve and said cold start valve in response to operational parameters of said engine.

17. A method of improving efficiency of a super-turbocharged engine system comprising: providing compressed air from a compressor of a super-turbocharger; mixing a portion of said compressed air with exhaust gases from said engine to create a gas mixture having a temperature that does not exceed a predetermined maximum temperature to prevent damage to a turbine of said super-turbocharger; driving said turbine with said gas mixture; 21 WO 2011/011019 PCT/US2009/051742 transferring excess turbine rotational mechanical energy from said turbine to a propulsion train that would otherwise cause said turbine to rotate at a speed which would cause damage to said compressor.

18. The method of claim 17 further comprising: transferring propulsion train rotational mechanical energy from said propulsion train to said compressor to reduce turbo lag.

19. The method of claim 18 further comprising: maintaining a sufficient flow of said source of air through said compressor by mixing said portion of said compressed air with said exhaust gases during operational phases of said engine when surge would otherwise occur.

20. The method of claim 19 further comprising: providing a catalytic converter that receives said exhaust gases and produces an exothermic reaction that adds heat to said exhaust gases; supplying said exhaust gases from an output of said catalytic converter to said turbine.

21. The method of claim 20 further comprising: providing a portion of said compressed air to an input of said catalytic converter during cold start conditions to add oxygen that assists said catalytic converter in initiating said exothermic reaction.

22. A method of improving efficiency of a super-turbocharged engine system comprising: providing an engine; providing a catalytic converter that is connected to an exhaust outlet proximate to said engine that receives engine exhaust gases from said engine that 22 WO 2011/011019 PCT/US2009/051742 activate an exothermic reaction in said catalytic converter which adds additional energy to said engine exhaust gases and produces catalytic converter exhaust gases at an output of said catalytic converter that are hotter than said engine exhaust gases; providing a flow of compressed air to an intake of said engine using a compressor; mixing a portion of said compressed air with said catalytic converter exhaust gases in a mixing chamber that is downstream from said catalytic converter to produce a gas mixture of said catalytic converter exhaust gases and said compressed air; regulating said flow of said compressed air into said mixing chamber using a control valve to maintain said gas mixture below a maximum temperature, and to maintain a flow of said compressed air through said compressor during operational phases of said engine when surge in said compressor would otherwise occur; supplying said gas mixture to a turbine that produces turbine rotational mechanical energy in response to flow of said gas mixture; transmitting said turbine rotational mechanical energy from said turbine to said compressor that uses said turbine rotational mechanical energy to compress a source of air to produce said compressed air when said flow of said gas mixture through said turbine is sufficient to drive said compressor; extracting at least a portion of said turbine rotational mechanical energy from said turbine and applying said portion of said turbine rotational mechanical energy to a propulsion train when said portion of said turbine rotational mechanical energy from said turbine is not needed to run said compressor; 23 WO 2011/011019 PCT/US2009/051742 providing propulsion train rotational mechanical energy from said propulsion train to said compressor to prevent turbo-lag when said flow of said gas mixture through said turbine is not sufficient to drive said compressor.

23. The method of claim 22 wherein said maximum temperature of said gas mixture is below a temperature at which said gas mixture would otherwise cause damage to said turbine.

24. The method of claim 23 wherein said maximum temperature of said gas mixture is below approximately 950'C.

25. The method of claim 23 wherein said efficiency of said engine is improved by not using a waste gate to expel excess gases of said gas mixture.

26. The method of claim 25 wherein said process of extracting excess turbine rotational mechanical energy from said turbine and providing propulsion train rotational mechanical energy from said propulsion train to said compressor comprises: using a transmission that couples said excess turbine rotational mechanical energy and said propulsion train rotational mechanical energy between said propulsion train and a shaft connecting said turbine and said compressor.

27. The method of claim 26 wherein said process of maintaining a flow of said compressed air during operational phases of said engine comprises: maintaining a flow of said compressed air through said compressor when said engine is operating at low.speeds and requires high torque by opening said feedback valve to reduce surge.

28. The method of claim 27 wherein said process of mixing said compressed air with said hotter exhaust gases in a mixing chamber comprises: 24 WO 2011/011019 PCT/US2009/051742 providing at least one opening in an exhaust conduit that is connected to a compressed air conduit so that said compressed air flows through said at least one opening and mixes with said hotter exhaust gases in said exhaust conduit.

29. The method of claim 28 further comprising: mixing a portion of said compressed air with said exhaust gases upstream from said catalytic converter during cold starts of said engine to provide oxygen to said catalytic converter that assists said catalytic converter in initiating said exothermic reaction.

30. A super-turbocharged engine system comprising: an engine; a catalytic converter connected to an exhaust conduit proximate to an exhaust outlet of said engine such that hot exhaust gases from said engine activate an exothermic reaction in said catalytic converter that adds energy to said hot exhaust gases and produces hotter exhaust gases; a compressor connected to a source of air that provides compressed air that has a pressure that is greater than a pressure level of said exhaust gases; a conduit that supplies said compressed air to said hotter exhaust gases so that at least a portion of said compressed air is mixed with said hotter exhaust gases to produce a gas mixture; a turbine that is mechanically coupled to said compressor and generates turbine rotational mechanical energy from said gas mixture; a valve that regulates flow of said portion of said compressed air through said conduit to maintain said gas mixture below a predetermined maximum temperature and to maintain a flow of air from said source of air through said 25 WO 2011/011019 PCT/US2009/051742 compressor during operational phases of said engine when surge in said compressor would otherwise occur; a transmission that provides propulsion train rotational mechanical energy from a propulsion train to said compressor to reduce turbo-lag when said flow of said exhaust through said turbine is not sufficient to drive said compressor to a desired boost level, and extracts excess turbine rotational mechanical energy from said turbine to maintain rotational speeds of said compressor below a predetermined maximum rotational speed at which damage would occur to said compressor.

31. The engine system of claim 30 further comprising: a controller that detects temperature levels of said gas mixture, engine rotational speed, a pressure level of said compressed air and engine load, and controls said operation of said valve and ratio of said transmission.

32. The engine system of claim 31 further comprising: a cold start control valve that provides another portion of said compressed air to said exhaust conduit upstream from said catalytic converter to add oxygen to said exhaust gases that assists said catalytic converter in initiating an exothermic reaction during cold starts. 26