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.