DESIGN AND DEVELOPMENT OF A TEST RIG TO ESTIMATE FATIGUE LIFE OF THE TIMING BELT OF I. C. ENGINE

Abstract

Timing belt mechanism of an internal combustion engine synchronizes the rotation of the crankshaft and camshaft. The power developed in I.C. engine, some power of that is utilized to operate timing belt mechanism. Timing valves are operated by camshaft with lever and spring mechanism. Engine valve should open and close at proper time during each inlet and exhaust strokes of the cylinder. The failure of timing belt in I.C. engine leads to problem to valve timing and this can cause collision between valves and piston in engines. It can causing serious engine damage by bending valves and breaking piston and it leads to complete breakdown or catastrophic engine failure. A large number of factors have influence on timing belt drive’s lifetime: wear, amount of transmitted power, operating environment, coaxiality of shafts and belt pulleys, handling before and during assembly and others. Failure of belt most frequently occurs because of damage of belt’s and belt pulley’s teeth or damage of tractive element due to wear and fatigue. Considering their purpose and very important role in transmission of power, motion and valve timing, it is necessary to know fatigue life of timing belt. The study was thus needed to analyze fatigue failure of timing belt. The paper includes designing and development of a test rig for estimation fatigue life of timing belt. Test rig is developed based on ISO and Automotive industry standards. The study involves observation of change of physical properties, wear and geometric parameters of the belt. Thereafter tooth deflection and tooth root strain is obtained by calculation. Tooth deflection and tooth root strain play important role in fatigue of the belt.