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Pick up and delivery vehicle applications such as parcel handling trucks represent an ideal duty cycle for Hybrid Electric Powertrains. The low speed, frequent stopping and starting operation provides good opportunities for enhancing engine behavior and recovering braking energy by adding an electric drive system to the vehicle. FedEx Express collaborated with the environmental advocacy group Environmental Defense to announce the Future Vehicle Program, with the goal of developing significant improvements in emissions and fuel economy for the familiar FedEx Express W700 parcel delivery vehicle. This paper describes the objectives, development activities, and test results for one of the vehicles submitted to this program. A team led by Eaton Corporation prepared the Direct Hybrid Electric Powertrain system, which received the highest ranking in the Future Vehicle Program evaluation.

A semiconductor capacitance -type accelerometer utilizing a pulse width modulation (PWM) electrostatic servo technique has been developed. Highly accurate detection of very small and low frequency acceleration became possible with the PWM sensing method. The limited air gaps between the movable and fixed electrodes ensured compatibility between high sensitivity and durability, while transverse sensitivity and temperature coefficient were reduced due to the symmetric structure of the sensing device. This sensor has been designed for the measurement range of 0 to ±1g, ±2g and 0 to 50Hz. The accelerometer is composed of two chips: the sensing device made by silicon micromachining technology and the custom IC made by bipolar CMOS technology. In this paper, we present the fundamental sensing principle, the sensing device, the custom IC and the characteristics of the new accelerometer.

This paper describes a state adaptive control method for vehicle suspensions proposed by Hitachi, Ltd. The objective of the control is to improve riding comfort and driving stability in reaction to road iregularities, exterior wind forces, and changes in vehicle loads as well as in reaction to inertial changes during cornering, breaking, and accelerating. The objective is attained by making considerable use of the relative displacement data between the body and the suspension. The state adaptive control system includes four shock absorbers whose damping forces can be tuned in three stages, four height sensors which measure the relative displacement, a vehicle speed sensor, and a microcomputer which decides the optimal damper stage. The validity of the proposed control method is shown through computer simulations and actual driving experiments. Vertical acceleration is reduced by about 55 % by switching from the soft damper to the hard damper in a computer simulation.

Generally in electric vehicles regenerative braking is incorporated to increase urban driving range on a single charge and to get the same brake torque as engine brake. In this paper analysis of the regenerative operation by thyristor chopper control is described. Firstly to clarify regenerative efficiency, the calculation of various losses such as commutation loss and thyristor loss which arises at braking mode is discussed, and it is described that the regenerative efficiency calculated from above losses agrees closely with test results. Secondly newly developed A.F.C. (Automatic Field Control) regenerative braking system is introduced. As in this A.F.C. regenerative control system, using shunt motor, field current is controlled inversely proportional to motor speed and regenerative operation is obtainable by low motor speed, this system is very suitable for electric vehicles.