Reduction drive

Abstract: A helical planetary gear assembly which is particularly adapted for use in a vehicle drive mechanism such as a four-wheel drive transfer case. The reaction member (ring gear) is rigidly secured to the housing; the input member (sun gear) is axially and radially located by a bearing; and the output member (planet carrier) is axially restrained but radially free to float. In direct drive the input and output are connected directly and the gears are unloaded, thus avoiding vibration and wear commonly experienced when running in reduction drive. The assembly requires only one mesh point when shifting to either the direct or reduction drive mode.

Abstract: A power transfer mechanism incorporates a planetary or epicyclic gear set which may be shifted between high and low-range conditions to establish torque proportioning and locked-up reduction drive modes. In the high-range mode, the carrier defines an input member and the sun and ring gears define output members. In the low-range mode, the sun gear defines an input member, the carrier an output member, and the ring gear a reaction member. A shifting sleeve includes relatively rotatable elements slidable together as a unit for establishing high and low-range conditions.

Abstract: Differential reduction drives on opposite sides of a vehicle are steer driven by a pair of worm gears (110) meshed with worm wheels (111) inputting steering torque into each reduction drive. The worm gears are rotationally interconnected so that the steering torque applied to the reduction drives is respectively equal and opposite. The arrangement allows a simple steering control shaft (46) to receive steering control torque for normal turning and driving torque for propulsion drive-assisted pivot turning. A pivot turn brake (120), applied to the drive torque train, can make pivot turning precise.

Abstract: In recent years, interest has been growing in the 2-Stroke Diesel cycle, coupled to high speed engines. One of the most promising applications is on light aircraft piston engines, typically designed to provide a top brake power of 100-200 HP with a relatively low weight. The main advantage yielded by the 2-Stroke cycle is the possibility to achieve high power density at low crankshaft speed, allowing the propeller to be directly coupled to the engine, without a reduction drive. Furthermore, Diesel combustion is a good match for supercharging and it is expected to provide a superior fuel efficiency, in comparison to S.I. engines. However, the coupling of 2-Stroke cycle and Diesel combustion on small bore, high speed engines is quite complex, requiring a suitable support from CFD simulation. In this paper, a customized version of the KIVA-3v code (a CFD program for multidimensional analyses) has been used to address ports and combustion chamber design of a new project (a 3-cylinder 1.8L engine, with a power rating up to 150 HP). Multidimensional calculations have been supported by 1D engine cycle analyses, using GT-Power. Two types of combustion-scavenging system have been considered, both of them featuring direct injection: a configuration with exhaust poppet valves and another one with piston controlled ports. A development of both projects has been performed through a coupled 1d-3d computational approach. A first set of KIVA calculations has been performed, in order to characterize the scavenging and the port flow patterns of both configurations, considering three different operating conditions, representative an aircraft engine. Then, several combustion simulations have been run, for defining two chambers able to match the project goals (high fuel efficiency, limited in-cylinder peak-pressure). For the two best configurations, the most interesting calculation results are presented in the paper.