The calculation of the tangential values of module m, pressure angle [alpha], helical angle [beta] on the base circle
, pinion [r.sub.bp] and wheel [r.sub.bw] base radii are evaluated in equations (4), (5), (6), (7) and (8) respectively:
In (Flores, 2013) a computational methodology for the optimized design of disccam mechanisms with eccentric translating roller followers is presented; the objective function takes into account: the cam base circle
radius, the roller radius, and the follower offset.
The geometry of an involute gear results in its having a pitch circle and a base circle
. The meshing force can be described as shown in Fig.
(2) Base circle
: The circle from which an involute tooth curve is generated or developed.
The base circle
radii for pinion and gear can be obtained as:
The profile called "direct profile" belongs to the positive side of an involute with the base circle
diameter dbd--the direct profile base circle
The most important geometrical parameter of asymmetric gears is the coefficient of asymmetry "k" defined as the ratio between the base circle
diameter of the inactive flank and the base circle
diameter of the active flank (Litvin et al., 2000).
In the optimisation phase of the study for this project, GIW discovered that increasing the geometry of the base circle
by 10% would reduce wear by 30%, while adding only 5% to capital costs.
The contour required for the scroll compressors, known as an "involute", is defined with reference to a base circle
. "You could look at it as the curve described by a point on a thread kept taut as it is unwound from a central core," says Mr Fletcher.
Instead of involute or other curved tooth forms, double-enveloping gears have straight-sided form is tangent to a common base circle
. It allows more tooth area contact.