Anand Md Poster FINAL_1429253936162
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DESIGN OF VALVE 1) Size of the valve port : Let ,a p = Area of the port, v p = Mean velocity of gas flowing through the port, a = Area of the piston, and v = Mean velocity of the piston. We know that, a p . v p = a . v So, a p = a . v / v p DESIGN OF ROCKER ARM (1) Design for fulcrum pin : Let , d 1 = Diameter of the fulcrum pin, l 1 = Length of the fulcrum pin. Considering the bearing of the fulcrum pin. Load on the fulcrum pin, R F = d 1 . l 1 . p b (2) Design for forked end : The load acting on the roller pin is F c . Let, d 2 = Diameter of the roller pin, and l 2 = Length of the roller pin. Considering the bearing of the roller pin. F c = d 2 . l 2 . p b The ratio of l 2 / d 2 may be taken as 1.25. Thickness of each eye = l 2 / 2 The radial thickness of the eye (t 3 ) is taken as d 1 / 2. Therefore, overall diameter of the eye, D 1 = 2d 1 (4) Design for rocker arm cross – section : Let, l = Effective length of each rocker arm, σ b = Permissible bending stress. Bending moment on the rocker arm, M = F e . l Also, Bending moment, M = σ b . Z (3) Design for tappet : Let, d c = Core diameter of the tappet, σ c = Permissible compressive stress The load on the tappet, F e = π/4 . (d c ) 2 . σ c . The outer or nominal diameter of the tappet (d n ) , d n = d c / 0.84 The diameter of the circular end of the rocker arm (D 3 ) and its depth (t 4 ) is taken as D 3 = 2d n ; and t 4 = 2d n (5) Design for valve spring : Let, W 1 = Initial load on the spring W 2 = Load at full lift = Full lift × Stiffness of spring Total load on the spring, W = W 1 + W 2 (2) Thickness of the valve disc : t = k. d p √(p / σ b ) Where , k = constant = 0.42 for steel & 0.54 for C.I. , d p = Diameter of the port in mm, p = Maximum gas pressure in N/mm 2 , σ b = Permissible bending stress in MPa or N/mm 2 , = 50 to 60 MPa for carbon steel and 100 to 120 MPa (3) Maximum lift of the valve : h = lift of the valve For conical valve, π d p . h cosα = π/4 ( d p ) 2 h = d p / 4 cosα Where ,α = Angle at which the valve seat is tapered = 30˚ to 45˚. For flat headed valve the lift is given by, h = d p / 4 (4) Valve stem diameter : The valve stem diameter (d s )is given by, d s = (d p / 8) + 6.35 mm to 11 mm GEC DAHOD MECHANICAL DEPARTMENT TITLE : DESIGN OF VALVE GEAR MECHANISM GUIDED BY : R.I.PATEL SIR PREPARED BY: SHAH ANAND P. (120183119023) PATEL SUNNY P. (120183119024) PATEL HARSHID K. (120183119022) PANCHAL HARSH K. (120183119021) CHAND PRAKASH S. (120183119020)
description
Machine design
Transcript of Anand Md Poster FINAL_1429253936162
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DESIGN OF VALVE 1) Size of the valve port : Let ,ap = Area of the port, vp = Mean velocity of gas flowing through the port, a = Area of the piston, and v = Mean velocity of the piston. We know that, ap . vp = a . v So, ap = a . v / vp
DESIGN OF ROCKER ARM (1) Design for fulcrum pin : Let , d1 = Diameter of the fulcrum pin, l1 = Length of the fulcrum pin. Considering the bearing of the fulcrum pin. Load on the fulcrum pin, RF = d1 . l1 . pb
(2) Design for forked end : The load acting on the roller pin is Fc. Let, d2 = Diameter of the roller pin, and l2 = Length of the roller pin. Considering the bearing of the roller pin. Fc = d2 . l2 . pb The ratio of l2 / d2 may be taken as 1.25. Thickness of each eye = l2 / 2 The radial thickness of the eye (t3) is taken as d1 / 2. Therefore, overall diameter of the eye, D1 = 2d1
(4) Design for rocker arm cross section : Let, l = Effective length of each rocker arm, b = Permissible bending stress. Bending moment on the rocker arm, M = Fe . l Also, Bending moment, M = b . Z
(3) Design for tappet : Let, dc = Core diameter of the tappet, c = Permissible compressive stress The load on the tappet, Fe = /4 . (dc)
2 . c. The outer or nominal diameter of the tappet (dn) , dn = dc / 0.84 The diameter of the circular end of the rocker arm (D3) and its depth (t4) is taken as D3 = 2dn ; and t4 = 2dn
(5) Design for valve spring : Let, W1 = Initial load on the spring W2 = Load at full lift = Full lift Stiffness of spring Total load on the spring, W = W1 + W2
(2) Thickness of the valve disc : t = k. dp (p / b) Where , k = constant = 0.42 for steel & 0.54 for C.I. , dp = Diameter of the port in mm, p = Maximum gas pressure in N/mm2, b = Permissible bending stress in MPa or N/mm
2, = 50 to 60 MPa for carbon steel and 100 to 120 MPa
(3) Maximum lift of the valve : h = lift of the valve For conical valve, dp . h cos = /4 ( dp )
2 h = dp / 4 cos Where , = Angle at which the valve seat is tapered = 30 to 45. For flat headed valve the lift is given by, h = dp / 4
(4) Valve stem diameter : The valve stem diameter (ds)is given by, ds = (dp / 8) + 6.35 mm to 11 mm
GEC DAHOD MECHANICAL DEPARTMENT TITLE : DESIGN OF VALVE GEAR MECHANISM GUIDED BY : R.I.PATEL SIR PREPARED BY: SHAH ANAND P. (120183119023) PATEL SUNNY P. (120183119024) PATEL HARSHID K. (120183119022) PANCHAL HARSH K. (120183119021) CHAND PRAKASH S. (120183119020)
