How to draw the cavity of the housing of a Wankel rotatory engine in AutoCAD/GStarCAD/ZwCAD


Use LitioLAB in different ways to draw the Wankel engine housing and any epitrochoid


The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion.



Check the following video:




The housing of a Wankel engine can be mathematically defined as a pair of parametric equations for X and Y, for the formula parameter varying from 0.0 to 2*PI. The formulas can be rewritten into a calculator-like form, as follows.



    X = c1*cos(r2d(3*u)) + c2*cos(r2d(u))
    Y = c1* sin(r2d(3*u)) + c2*sin(r2d(u))
The parameters for this example are:
    c1 = 10.0
    c2 = 60.0
    u = 0.0 to 2*PI



    ZwCAD users need to check LitioLAB user manual to review the math functions available and how to adapt the formulas to ZwCAD.

    The R2D (radians-to-degrees) conversion function is not available in ZwCAD. Use 180/PI as a multiplying factor instead.

Since the oval-like housing of a Wankel engine is an epitrochoid, this can also be done with the Spirograph function of LitioLAB.



The Spirograph parameters of this example:

    D = 40.0 Turns = 3
    C = 1.0
    R = -30.0
    A0 = 0.0
    L = 60.0
    B0 = 0.0
    N = 1000



And since these graphs are polylines, they can be extruded and used to generate CAD solids for further processing and eventually, for CNC machining, or 3D printing.



Back to case studies.