Fixture to Monitor Constant Velocity Joint Articulation and Lash

Abstract

The hydraulic pump and motor group of the EPA at the National Vehicle Fuel Emissions Laboratory in Ann Arbor has been doing research and design of hydraulic hybrid vehicles using hydraulic pistons pumps, particularly bent axis pumps, to assist in the propulsion of automobiles. The pump consists of two halves which are rotating and at angles to each other, causing the pump to require the use of a CV Joint. Due to durability issues encountered during testing, the EPA has asked us to create a fixture that will measure the lash in the CV joint throughout its angular operating range. The key requirements of this project are the precise alignment of the joint, as well as the accuracy of the measurements. The EPA requires us to have measurement accuracies of up to 0.1 degrees in some of our measurements and to align certain joint surfaces to within .010 in. The customer also requires us to measure the frictional torque that occurs in the joint and to be able to do this throughout the entire rotation of the joint to note if there are any areas of particularly high resistance.