Spline-type cam phaser

The present invention relates to a cam phaser apparatus for controllably varying the phase relationship between the crankshaft and the camshaft of an internal combustion engine; more particularly, to a cam phaser having concentric splined elements counter-rotatable by a splined piston therebetween; and most particularly, to a splined cam phaser wherein the parts are optimized for ease and economy of manufacture, reduced phaser size, and improved phaser performance. An improved splined cam phaser includes four assemblies: a sprocket assembly, an inner hub assembly, a cover assembly, and a piston assembly. The joined assemblies provide phaser function at reduced manufacturing cost. The component parts of the assemblies are re-configured from analogous parts in the prior art cam phaser to permit much of the improved phaser to be manufactured inexpensively by powdered metal forming or by stamping or drawing from sheet metal, in contrast with the prior art phaser wherein all parts are formed expensively either by machining from forged blanks or by investment casting. These changes reduce not only the cost of manufacture but also reduce the weight and axial length of the phaser, an important customer acceptance criterion, and improve the speed of response. Further, the proportions of some parts are altered such that all radial and axial loads are borne by a single large bearing in place of two small sequential bearings in the prior art phaser, thus reducing variability in axial alignment of the component parts.