Top Banner

of 9

Bajaj Pulsar 180 Dts-i

May 30, 2018

Download

Documents

abhij1306
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
  • 8/14/2019 Bajaj Pulsar 180 Dts-i

    1/9

    BAJAJ PULSAR 180 DTS-i

  • 8/14/2019 Bajaj Pulsar 180 Dts-i

    2/9

    DTS-i ENGINE

  • 8/14/2019 Bajaj Pulsar 180 Dts-i

    3/9

  • 8/14/2019 Bajaj Pulsar 180 Dts-i

    4/9

    Determination of important engine parameters

    Mean piston speedSp = 2LN

    Now L = stroke

    = 56.4mm = 0.0564m

    N = 8000rev/min = 133.33rev/s

    Sp = 2x.0564x133.33 m/s

    = 15m/s

    Mean Effective Pressure

  • 8/14/2019 Bajaj Pulsar 180 Dts-i

    5/9

    mep = P(kW)nrx103

    Vd(dm3)xN(rev/s)

    Now P = Power = 11.7 kW

    N = 8000 rev/min = 133.33 rev/s

    Vd = Displacement = 178.6cc

    mep = 11.7 x 2 x 1000

    .1786 x 133.33

    = 982.6 kPa

    Specific Power

    P/Ap = 1 x mep x Sp

    2nr

    where mep = mean effective pressure

    Sp = mean piston speed

    P/Ap = 0.25 x 982.6 x 15

    = 36.85 kW/dm2.

    Volumetric Displacement

    Vd = n x (/4) x B2 x L

    where n = no. of cylinders = 1

    B = bore = 63.5 mm

  • 8/14/2019 Bajaj Pulsar 180 Dts-i

    6/9

    L = stroke = 56.4 mm

    Vd = (/4) x (0.0635)2 x 0.0564

    = 0.18 dm3.

    Detailed design of

    (a) Cylinder

    The cylinder wall is subjected to gas pressure and the piston side thrust.

    The gas pressure produces two types of stresses: longitudinal and

    circumferential which act at right angle to each other and so the net stress

    in each direction is reduced.

    sl = longitudinal stress = Force/Area

    = /4 x D2x pmax

    /4 x (Do2 D)2

    where D = cylinder inside dia.

    Do= cylinder outside dia.

    and pmax= max. gas pressure

    sc= circumferential stress = pmaxx D

    2t

    Net sl = sl sc/m

    and sc = sc - sl/m

  • 8/14/2019 Bajaj Pulsar 180 Dts-i

    7/9

    where1/m = Poissons ratio

    To calculate wall thickness:

    t = pmax x D + k

    2sc

    where t = wall thickness in cm.

    sc= max. hoop stress = 350 kg/cm2

    k = reboring factor = 1.25 mm

    pmax = 80 kg/cm2

    Hence t = [(80x 6.35)/(2 x 350)] + 0.125

    = 8.5 mm

    Now D = 63.5 mm

    and Do= 63.5 +2 x 8.5 = 80.5 mm

    Apparent longitudinal stress

    sl = [ (6.35)2 x 80] / (8.052 6.352)

    = 131.8 kg/cm2.

    Apparent circumferential stress

    sc = (80 x 6.35) / 1.7

    = 298.8 kg/cm2.

    Taking 1/m =

    Net sl = 131.8 298.8/4 = 131.8 74.7

    = 57.1 kg/cm2.

    sc = 298.8 131.8/4 = 298.8 32.95

    = 265.8 kg/cm2.

  • 8/14/2019 Bajaj Pulsar 180 Dts-i

    8/9

    Length of cylinder = 10 to 15% of stroke = 1.15 x 5.64

    = 6.5 cm.

    (b) Piston

    Thickness of piston head

    t = ( 3pD2/16st )1/2

    where t = piston head thickness

    D= cylinder bore = 6.35 cm

    p = max. gas pressure = 80 kg/cm2

    st = allowable stress in bending = 400 kg/cm2

    Hence t = [(3x80x6.352) / (16 x 200)]1/2

    = 1.72 cm

    Piston Rings

    The radial width of the ring is selected as to limit the wall pressure to 0.25

    to 0.42 kg/cm2

    wr = D (3pw/ st)1/2

    where wr = radial width of the ring

    pw = wall pressure = 0.25 kg/cm2

    st = allowable stress in bending = 850 kg/cm2

    Hence wr = 6.35 x (3x0.25/850)1/2

    = 0.2 cm.

    Piston Skirt

    The portion of the piston barrel below the ring section upto the open end is

    known as skirt and it takes the side thrust of the connecting rod. Its length

  • 8/14/2019 Bajaj Pulsar 180 Dts-i

    9/9

    should be such that the side thrust pressure does not exceed 2.5 kg/cm2 for

    low speed engines and 5.0 kg/cm2 for high speed engines.

    Side thrust ./4.D2.p = lDpt

    = coefficient of friction (0.03 to 0.10)

    D = piston diameter = 6.35 cm

    p = gas pressure = 80 kg/cm2

    l = skirt length

    pt = side thrust pressure = 2.5 kg/cm2

    Hence 0.05 x /4 x 6.352 x 80 = I x 6.35 x 2.5

    l = 8 cm.\