1 design of fulcrum pin let d1 diameter of the

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Unformatted text preview: g on the rocker arm of the exhaust valve. We know that gas load on the valve, π π P1 = (dv )2 pc = (80) 2 0.4 = 2011 N 4 4 Weight of associated parts with the valve, w = m · g = 0.4 × 9.8 = 3.92 N ∴ Total load on the valve, P = P1 + w = 2011 + 3.92 = 2014.92 N ...(i) Initial spring force considering weight of the valve, π π (d )2 ps − w = (80)2 0.02 − 3.92 = 96.6 N 4v 4 The force due to valve acceleration (Fa) may be obtained as discussed below : We know that speed of camshaft Fs = ...(ii) 1196 n A Textbook of Machine Design N 1500 = = 750 r.p.m. 2 2 and angle turned by the camshaft per second = Fig. 32.25 750 × 360 = 4500 deg / s 60 ∴ Time taken for the valve to open and close, = Angle of action of cam 110 = = 0.024 s Angle turned by camshaft 4500 We know that maximum acceleration of the valve t= 2 2 2π 2π 2π 2 ∵ω = a = ω2 · r = t t r = 0.024 0.0125 = 857 m / s ... ∴ Force due to valve acceleration, considering the weight of the valve, Fa = m · a + w = 0.4 × 857 + 3.92 = 346.72 N ... (iii) and maximum load on the rocker arm for exhaust valve, Fe = P + Fs + Fa =...
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