Mark Walls

Parallel hybrid drivetrain

A hybrid vehicle includes an internal combustion engine, an electric motor/generator and a battery. The drivetrain includes a planetary gear in which the engine is coupled to the sun gear, the motor/generator to the ring gear and the vehicle wheels to the carrier of the planetary. A controller switches the vehicle between electric, assist, charge and regenerative modes of operation and substantially decouples the engine speed from the vehicle speed, enabling the engine to operate at peak efficiency. Additional overdrives are included to enable the engine to operate at optimum speed in the various modes of operation.

42-Volt Electric Air Conditioning System Commissioning and Control for a Class-8 Tractor

The electrification of accessories using a fuel cell as an auxiliary power unit reduces the load on the engine and provides opportunities to increase propulsion performance or reduce engine displacement. The SunLine Class 8 tractor electric accessory integration project is a United States Army National Automotive Center (NAC) initiative in partnership with Cummins Inc., Dynetek Industries Ltd., General Dynamics C4 Systems, Acumentrics Corporation, Michelin North America, Engineered Machine Products (EMP), Peterbilt Motors Company, Modine Manufacturing and Masterflux. Southwest Research Institute is the technical integration contractor to SunLine Services Group. In this paper the SunLine tractor electric Air Conditioning (AC) system is described and the installation of components on the tractor is illustrated. The AC system has been designed to retrofit into an existing automotive system and every effort was made to maintain OEM components whenever modifications were made. Hardware modifications were limited to replacing the engine driven compressor for a 42 volt DC driven one, exchanging the expansion orifice for a thermal expansion valve and positioning the components to minimize the length of refrigerant lines. The thermodynamics and PID control algorithms are discussed. Closed loop test results are presented in controlled ambient conditions. Analysis of reversed Carnot cycle changes due to transient operation and coefficient of performance changes are given. INTRODUCTION The engine driven air conditioning system on the 2002 Peterbilt 385 is used for maintaining a comfortable incab temperature and as a windshield defroster. The Original Equipment Manufacturer (OEM) system includes a Sanden SD7 engine driven compressor that draws approximately 6 kW at full load. One disadvantage of this compressor is that it is the same one that is used on all of their trucks, and therefore it is sized for the trucks with the full size sleeper. Peterbilt and Modine engineers have designed this system to provide up to 25000 BTU/hr of cooling. Other disadvantages of having the engine driven compressor include constant parasitic losses from clutch drag, inability to operate the compressor in its efficient zones, and packaging.