Wear of Chain Tensioners and Chain Guide Polymers in a Diesel Engine

Dr Alan Ward, University of Sheffield
Prof Rob Dwyer-Joyce, University of Sheffield
Mr Geoff Josey, Ford Motor Company

With the increasing use of chain drives for timing applications in the automotive industry, the wear of the drive component is becoming important. Some research has been undertaken to determine the wear of drive chains but the study of the associated wear of the guides and tensioning devices is limited. The guide materials are under severe loading conditions and are frequently marginally lubricated.



In the automotive industry chain drive component durability is frequently assessed by engine dyno tests. This test procedure is expensive, time consuming and does not determine the wear processes which limit the life of the materials in the application. In order to keep pace with fast moving engine development it is necessary to analyse the cause of the wear observed.

This project aims to observe and analyse the drive chain path and contact with the polymer guides for two different chain and sprocket configurations. Iniitally this was done using a motred engine and high speed photography to study the dynamic pattern of chain motion. The impact betwen the chain and tensioners as it enters contact can be particularly severe. The tensioners are then subject to both siding and impact loading.

Photoelastic stress techniques were used to quanitfy the stress on the tensioners and hence build a life model. A tensioner was machined from an epoxy resin and placed inside a chain test rig. An arrangement of polarisers and lenses was used to monitor the stress fringes during chain passage. High speed video photography was used to caputre the fringe images. The fringe pattern was used to determine the contact stress and hence chain impact loading. The dynamic loading was several times that calculated from simple static chain tension load.

Sponsors

We are grateful to the Ford Motor Company Diesel Developments Group and to the EPSRC for sponsorship of this work.

Publications:

    1. Dwyer-Joyce, R.S., Lewis, R., Ward, A., Patterson, E.A., (2006), Determination of Impact Stresses in an Automotive Chain Drive Component�, Journal of Engines, Transactions of the SAE 2006, pp. 393-399, SAE Paper 2006-01-0766
    1. Ward. A. and Dwyer-Joyce, R.S., (2001), Model Experiments on Automotive Chain Drive Systems, Proceedings of the 27th Leeds-Lyon Symposium on Tribology, Elsevier Tribology Series No. 39, pp. 851-861.