Unformatted text preview: angle
of valve seat 1/2° to 1° larger than the valve angle as shown
in Fig. 32.23. This results in more effective seat.
(d) Valve stem diameter
The valve stem diameter (ds) is given by
ds = dp
+ 6.35 mm to
+ 11 mm
8 ...(In this case, α = 0°) Fig. 32.23. Valve interference angle. Note: The valve is subjected to spring force which is taken as
concentrated load at the centre. Due to this spring force (Fs), the stress in the valve (σt) is given by 1.4 Fs 2d s 1 − 3 2
dp t Example 32.6. The conical valve of an I.C. engine is 60 mm in diameter and is subjected to a
maximum gas pressure of 4 N/mm2. The safe stress in bending for the valve material is 46 MPa. The
valve is made of steel for which k = 0.42. The angle at which the valve disc seat is tapered is 30°.
Determine : 1. thickness of the valve head ; 2. stem diameter ; and 3. maximum lift of the valve.
Solution. Given : dp = 60 mm ; p = 4 N/mm2 ; σb = 46 MPa = 46 N/mm2 ; k = 0.42 ; α = 30°
1. Thickness of the valve head
We know that thickness of t...
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- Spring '11
- Combustion, Internal combustion engine, pistons, Connecting rod, Engine technology, piston pin