Patent ID: 7322329
Filing Date: 2008-01-29
Classification: F01L

Abstract:
1. In a population of DRVHL subassemblies wherein each DRVHL subassembly has an ascertainable value of leakdown and a shim-corrected residual value of mechanical lash, and wherein the leakdown value and the residual lash value of each DRVHL subassembly contribute additively to a valve overlap range when the finished DRVHL is used in an internal combustion engine, and wherein the population exhibits a range of variation of engine valve overlap when a range of leakdown values is combined at random with a range of residual lash values during assembly of the individual DRVHL subassemblies in the population of DRVHL subassemblies, a method for reducing said range of variation of valve overlap comprising the steps of: a) ascertaining a leakdown value for each DRVHL subassembly; b) characterizing each ascertained leakdown value relative to said distribution of leakdown values for said population of subassemblies; c) associating each subassembly with its relative leakdown value; d) ascertaining an as-manufactured lash value for each subassembly; and e) selecting and installing in each subassembly a lash shim selected from a population of shims having various thicknesses to provide a residual lash value for each subassembly that is complementary to said leakdown value to form said finished DRVHL.