This SBIR Phase I project will develop a mechanical device that provides functionality as a turbocharger and that will recuperate exhaust energy to be transferred to the transmission when boosting is not needed. The innovation is a unique design that integrates turbocharging, turbocompounding, and supercharging into one compact device that uses an infinitely variable speed transmission.
The broader/commercial impact of the project will be a reduction in fuel consumption in two ways. First is direct heat and energy recuperation from the exhaust stream. Second is to enable downsizing of internal combustion engines as a means to increase fuel economy. Turbocharging can be used for that purpose but adds driveability issues (turbo-lag). The proposed innovation could solve this problem.
." This feasibility project was designed to physically test a new application of SuperTurbocharger technology that was originally presented in SAE white paper 2010-10-1231. This goal for the project was to demonstrate a revolutionary approach to improving fuel efficiency for an automotive gasoline engine. The efficiency gain is realized through a unique combination of capabilities that: 1) Eliminates the requirement for fuel cooling in turbocharged engines. 2) Recovers exhaust energy and turbo-compounds back to the engine. 3) Enables higher engine power and facilitates engine downsizing. At the center of the project is the SuperTurbocharger itself. The device is a combination of a Continuously Variable Transmission (CVT) and a planetary driven turbocharger. The SuperTurbocharger effectively allows for control of the speed ratio between the engine and the turbine/compressor shaft. This unique combination allows for a single device capable of supercharging, turbocharging and turbo-compounding. When torque is flowing from the engine the device behaves as an ultra efficient supercharger. Engine power is used to accelerate the system during transients and any operating condition where the requested speed/power from the compressor exceeds what is collected by the turbine. Since the turbine aids in the supercharging effort, only a fraction of engine power is required compared to that of a standard supercharger. The SuperTurbocharger utilizes a high efficiency custom designed turbine, which is not restricted by inertia and design limitations of standard turbocharger turbines. This high efficiency turbine collects more power than the compressor requires at most operating conditions. When the turbine is collecting more exhaust energy than is required to drive the requested compressor speed, the CVT becomes a brake and the torque reverses. The torque then flows from the SuperTurbocharger back to the engine in a process called turbo-compounding. This project takes the SuperTurbocharger to a new level by placing the catalyst between the exhaust manifold and the turbine. The catalyst is half the size of a standard catalyst due to improved mass flow and temperatures (which also correlates to improved cold start emissions). Additionally, an air bypass valve allows for a portion of compressed air to be directed to a mixing chamber between the catalyst and the turbine inlet. In a normal turbocharger, the turbine temperature limit is maintained by using extra fuel. In this project, that temperature was controlled with air mixing. The on-engine testing conducted in this project conclusively showed that turbine inlet temperature can be controlled with bypass air. This eliminates wasteful fuel cooling. The bypass air adds to the expansive effect from the exhaust passing through the catalyst and is collected by the turbine. This allows for greater available total engine power through turbo-compounding. The ability to drive any boost level combined with compounding power shows that ultra efficient engine downsizing is possible.
