Engine Gear Research Articles

CAD of worms and their machining tools

To develop high-quality products, geometric modeling is needed in gear engineering to calculate the workpiece and tool geometry of worms, threads, or similar mechanical elements that can be described by helical or rotatory surfaces and that are to be generated by milling, grinding, or whirling. A survey will be given on the theoretical background, corresponding procedures, and illustrating examples of application concerning: (a) design of gear or worm profiles by means of curve primitives, their motion and manipulation; (b) calculation of conjugate gear profiles subjected to trochoidal motion; (c) calculation of arbitrary plane intersections of helicoids; and (d) calculation of the rotatory machining tool surface for a given worm and the inverse problem, including the solution of the undercut problem. Basic to the achieved integrated approach to CAD/CAM in this field is a discrete curve representation as sequence of points, tangent lines, and osculating circles providing higher geometrical information about curve and surface shape, which is also of high functional and economical importance for technological decisions.

Radiation efficiency as a factor in the design of engine components

The importance of radiation efficiency as a factor in the design of engine components is shown. The sound power reduction of a two‐piece engine gear cover was the goal. In the past, the action taken was to reduce the vibration amplitude. This ignores the role of radiation efficiency, often assumed to be one. Wallace [C. E. Wallace, J. Acoust. Soc. Am. 51, 926–945 (1972)] has shown how to analytically calculate radiation efficiency. Three models of the gear cover were developed. The standard gear cover comprises the flat steel plate attached to the block and an aluminum shell covering the gears. The first model, ♯1, greatly stiffened the shell; the second model, ♯2, greatly stiffened the flat plate; and the third model, ♯3, reversed the units, i.e., an aluminum shell was attached to the block and thin steel cover was used to enclose the gears. The model showed decreasing sound power levels from ♯1 to ♯3. A prototype part made up to the specifications of number ♯3 showed sound power measurements, using acoustic intensity methods, in close agreement with predictions.

歯車工学における一,二の話(<小特集>歯車)

歯車工学における一,二の話(<小特集>歯車)

Fuel additive : A new system and lubricant for rocket engine gear boxes : M. A. Hartman. Lubrication Eng., 18 (1962) 114–123; 16 figs., 6 tables, 11 refs.

Fuel additive : A new system and lubricant for rocket engine gear boxes : M. A. Hartman. Lubrication Eng., 18 (1962) 114–123; 16 figs., 6 tables, 11 refs.