Design of a 200 horsepower aeronautical engine . :; |.^ , --/^.oofte 1 i:-Vx::, .I-. ;.:;;: t ??>).•.>.; i*v - .. ;j Ji J J v PIT J ,? :? Page # and this is, of course, greatest in thecase of the exhaust valve. The exhaust valvemust be lifted against the force due to inertiaof the valve, combined with the initial springpressure and the pressure of the gases in thecylinder near the end of the expansion stroke. Thelatter pressure according to Heldt is 50 lbs. persq. inch. In the case of the inlet valve only the inertiaof the valve and the spring tension need be con-sidered, as the
Design of a 200 horsepower aeronautical engine . :; |.^ , --/^.oofte 1 i:-Vx::, .I-. ;.:;;: t ??>).•.>.; i*v - .. ;j Ji J J v PIT J ,? :? Page # and this is, of course, greatest in thecase of the exhaust valve. The exhaust valvemust be lifted against the force due to inertiaof the valve, combined with the initial springpressure and the pressure of the gases in thecylinder near the end of the expansion stroke. Thelatter pressure according to Heldt is 50 lbs. persq. inch. In the case of the inlet valve only the inertiaof the valve and the spring tension need be con-sidered, as the valve does not have to be liftedagainst a pressure. According to Heldt the force .required to lift the exhaust valve is approximately75 lbs. per sq. inch of valve area. Referring to Fig. 3, Let L = distance between adjacent = distajice of the centre of the cam fromthe farthest bearing. P = load on c&m in Ibe, ijiJ m RSUJBj! Oil J .It iif.^-ltl jcf « irr a^ob ?J 67.[ST io -pJ- i .iifUX .iji ai iji-^o no Page #47. /^/... 5 fiU. i:). xe / .- ;,:) .^ _, ,. f Jx L .t . i. r; :t Lt .;? Page # the exhaust valve. For the inlet valve, assume the maximum Pequal to twice the mean spring pressure or,P = 2 X 70 s 140 s= :xL 8 X =: .649 V -2 J From the table, (2x + 2x - 4x ) s= .104. Therefore, j 140 X (
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Keywords: ., bookcentury1900, bookdecade1920, bookiddesignof200h, bookyear1920
