N112-165 TITLE: High Efficiency, Compact, and Cost Effective Variable Speed Engine Accessory Drive System

TECHNOLOGY AREAS: Ground/Sea Vehicles

ACQUISITION PROGRAM: EPE FY12-04 Fuel Efficient MTVR FNC and PM MTVR

OBJECTIVE: Design, build, and demonstrate a cost effective variable speed device that can efficiently drive engine accessories and power takeoff devices on engines relevant to both commercial and military applications. Applications include Class 4 through 8 trucks for commercial industry as well as tactical vehicles for military application (MRAP, HMMWV, MTVR, FMTV).

DESCRIPTION: Commercial products, which achieve variable speed drive for accessories (fans, pumps) both hydraulically and electrically have been demonstrated to provide fuel savings in commercial applications.

Baseline fixed ratio belt or gear driven accessory drives are designed to provide an input speed to satisfy particular component functions for all devices on the system. Due to a lack of multi speed drive, this generally causes the components to be oversized for all but the worst case operating condition. For instance, typical clutched fan drives (on/off ) provide either excessive flow or insufficient flow required to satisfy component temperature conditions in all but the most extreme cooling environments, consuming greater power than relative to the ideal of "right sizing".

While a true infinitely variable speed drive for all accessories may provide the most performance benefit, a drive of several discrete speeds may provide the most value within the cost constraints and customer requirements. The exploration of the design space to include analyses and tradeoffs within the constraints of estimated manufacturing costs is the intent of this SBIR.

Fuel consumption reduction has been demonstrated on the Superbus project through the electrification of drive mechanisms for the fan, A/C condenser, power steering, and air pumps. The fan drive was originally a simple fixed geometry pump/motor with a pressure regulator and was switched to a sophisticated electric drive system. The conclusion of the study was "accessory electrification would result in a 13-15% improvement in overall fuel economy". As noted by the authors of the study "if complete accessory electrification is not feasible, it is estimated that most of the fuel savings (78% AC off, 81% AC on) can be achieved by electrification of just the engine fan and AC compressor."

Numerical analysis of the Bradley fighting vehicle indicates for the Munson Fuel Economy course at Aberdeen Proving Grounds in Maryland under 80 degrees F conditions, fuel consumption can be reduced approximately 7% by replacing a functionally on/off fan drive with an efficient eight discrete speed fan drive. Additionally, gains of 5% appear likely over a wide range of speeds, courses, and ambient temperatures.

The commercially available products currently do not satisfy the military user, and commercially desirable requirements of low cost, complexity, and fuel consumption, or the derived requirements of high transmission efficiency with appropriate ratio coverage. In order to demonstrate commercial applicability, the targeted military applications (MRAP, HMMWV, MTVR, etc) have common engines and fan drive systems with commercial class 4-8 trucks.

PHASE I: Provide estimations of relative improvements for providing variable speed drive to accessories, and develop a proof of concept design for an accessory drive system for the MTVR or similar vehicle, which maximizes cost/benefit ratio within an estimated cost envelope to be negotiated.

PHASE II: Develop and demonstrate the defined prototype system in a realistic environment. Conduct testing to prove feasibility over extended operating conditions.

PHASE III: This technology could be integrated into the next generation of Fuel Efficient USMC MTVRs upon successful FNC transition. In addition, all Class 4-8 military ground vehicle program offices could utilize the results of this effort.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: In addition to DoD, the mining, trucking, forestry, and farming industries could all benefit from this potential efficiency increase.

REFERENCES:
(1) DOE More Electric Truck: http://www1.eere.energy.gov/vehiclesandfuels/features/fcvt_feature_truck.html

(2) Superbus: http://www.cts.umn.edu/Research/ProjectDetail.html?id=2008078 Page, R., Hnatczuk, W., Kozierowski, J., "Thermal Management for the 21st Century � Improved Thermal Control & Fuel Economy in an Army Medium Tactical Vehicle." SAE Paper 2005-01-2068 (2005).

KEYWORDS: multi speed drive, fuel efficiency, compact drive design, high transmission efficiency with appropriate ratio coverage, low cost, low complexity,

** TOPIC AUTHOR (TPOC) **

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