Position of the piston of engine with respect to crank angle

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Equation / Last modified by KurtHeckman on 2019/03/27 23:36
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ID
EmilyB.Position of the piston of engine with respect to crank angle
UUID
58597a45-57ee-11e6-9770-bc764e2038f2

The Position of the piston of engine with respect to crank angle calculator computes the Piston_motion_geometry.pngposition of a piston pin from the crank center based on the rod length, the crank angle and the crank radius.

INSTRUCTIONS: Choose units and enter the following:

  • (r) This is the crank radius
  • (A) This is the crank angle
  • (l) This is the rod length.

Piston Position (x): The position is returned in inches.  However, this can be automatically converted to compatible units via the pull-down menu.

The Math / Science

The Position of the piston of engine with respect to crank angle expresses the motion of a non-offset piston connected to a crank through a connecting rod (as would be found in internal combustion engines).  The formula for the piston position is:

       `x=rcosA +sqrt(l^2-r^2sin^2A)`

where:

  • x = piston position
  • r = crank radius (distance between crank pin and crank center)
  • A = crank angle (from cylinder bore centerline at TDC)
  • l = rod length (distance between piston pin and crank pin)

References


Wikipedia (https://en.wikipedia.org/wiki/Piston_motion_equations)