Repeatability of Impedance and Ripple Tests for Automotive Pumps

Pumps are usually tested for performance and efficiency as well as other pump characteristics. With the increased awareness of Noise, Vibration and Harshness (NVH) in the automotive industry, new standardized tests have evolved for testing pumps. Two major tests are the impedance and ripple tests. Information collected on these signatures of pumps is vital for the success of any Fluid Born Noise (FBN) analysis of these important components and the system in which they function.

The purpose of this paper is to study the repeatability and reproducibility of such tests for the same pump. Production variability will be found when pumps of the same ‘category’ or part number are tested. The information presented here is important for the generalization of these tests and establishing them as a part of the research, development and design process. A set of pumps commonly used in the vehicle is put to the test. Another objective of these tests is to show how impedance and ripple tests can be used to describe the quality of the tolerancing practice used in designing and manufacturing these pumps from an NVH viewpoint.