I have also added this article under the piston designs, but I may wish to ask separately, but also as a subject, I am sorry for another topic. a = Piston pin ¼ full length. åP = Gas force per piston after combustion. lb = Connecting rod width. lp = Piston pin length. di = Piston pin inner diameter. do = Piston pin outer diameter. j = Navigation space. Mo = Bending moment. W = moment of resistance. D = Piston skirt diameter. Pmax = Max pressure at the end of combustion. Yacut & A; = Oil film strength. PISTON PIN CALCULATIONS: lp = 0.9 * D lp = 0.9 * 7.76 lp = 6.984 cm => lp = 69.84 mm åP = [p * D² / 4] * Pmax åP = [p * 7, 7² / 4] * 36 åP = 1676,3853 kg / cm² lp = 4 * a 6,984 = 4 * aa = 1,746 cm => a = 17,46 mm l '= 3 * take' = 3 * 1,746 l '= 5,238 cm => l '= 52.38 mm lb = 2 * a lb = 2 * 1.746 lb = 3.492 cm => lb = 34.92 mm & yacute; is the maximum oil film strength that the oil used in the engine creates and can bear. It varies according to the oils used in the engines. For the engine we designed, the oil film resistance is 250 kg / cm². Yacut & A; = (åP / 2) / A 250 = (1676,3853 / 2) / AA = 3,3528 cm² A = a * do 3,3528 = 1,746 * do do = 1,920275 cm => do = 19,20275 mm Bending Moment Calculation: Bending moment occurs on the piston pin due to the end of combustion pressure. This moment will be taken into consideration in material selection. Mo = (åP / 2) * ((3 * a / 2) - (2 * a / 4)] Mo = (1676,3853 / 2) * ((3 * 1,746 / 2) - (2 * 1,746 / 4 )] Mo = 1463,4845 kg / cm => Mo = 14634,845 kg / mm PISTON PIN MATERIAL It is possible to choose mixed materials in various ratios as piston pin material. What should be considered in the selection of materials is that it can withstand the force, cutting and torsion transmitted by the piston at the end of combustion. The piston pin material called EC60 Steel in DIN norms was used for the piston pin material we designed. The values and the alloy ratio of EC60 Steel are given below. EC60 STEEL C = 0.12 ~ 0.18 Kz = 70 ~ 90 kg / mm² (7000 ~ 9000 kg / cm²) Cr = 0.6% ~ 0.18 se = 0.7 * Kz kg / mm² (4900 ~ 6300 kg / cm²) Mn = 0.4% ~ 0.6 se ~ = 3000 kg / cm² Si = 0.33% W = Mo / se ~ W = 1463.4845 / 3000 W = 0.4878 cm3 W = [p (do4 - di4)] / 32 * do (do4 - di4) = 32 * do * W / p di = 4Ö do4 - [32 * do * W / p] di = 4Ö 1.9202754 - [32 * 1 , 920275 * 0,4878 / p] di = 1,4192 cm => di = 14,192 mm l 'Piston bore 52,38 mm A ¼ of the full length of the piston pin 17,46 mm åP Gas force per piston end of combustion 1676,3853 kg / cm² Lb Connecting rod width 34,92 mm Lp Piston pin length 69,84 mm Di Piston pin inner diameter 14,192 mm Do Piston pin outer diameter 19,2028 mm J Travel clearance 1.2 mm Note: Piston pin, It is moving in the connecting rod, tight fit in the piston.
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