The
REVETEC Engine design consists of two counter-rotating
“Trilobate” (three lobed) cams geared together, so both
cams contribute to forward motion. Two bearings run
along the profile of both cams (four bearings in all)
and stay in contact with the cams at all times. The
bearings are mounted on the underside of the two
inter-connected pistons, which maintain the desired
bearing to Trilobe clearance throughout the stroke.
The two cams rotate and raise the piston with a
scissor-like action to the bearings. Once at the top of
the stroke the air/fuel mixture is fired. The expanded
gas then forces the bearings down the ramps of the cams
spreading them apart ending the stroke. The point of
maximum mechanical advantage or transfer is around
20-30deg ATDC (when the piston moves approximately 10%
of its travel) making the most of the high cylinder
pressure.
This compares to a conventional engine that reaches
maximum mechanical advantage around 60-70deg ATDC.
(after the piston has moved through just over 40% of its
travel, losing approximately half of the cylinder
pressure). |
The
effective cranking distance is determined by the length
from the point of bearing contact to the centre of the
output shaft (not the stroke). A conventional engine's
turning distance is half of the piston stroke. The
piston acceleration throughout the stroke is controlled
by the cam “grind” which can be altered to suit a wide
variety of fuels, torque requirements and/or rev range.
The piston assembly slides rigidly through the block via
an oil pressure fed guiding system eliminating piston to
cylinder-bore contact.
This reduces wear and lubrication requirements in the
cylinder, and also reduces piston side shock making
ceramic technology suitable.
One module can either comprise of two trilobate cams and
either two, or four pistons in an “X” configuration.
The counter rotation is performed by a reverse gear set
at a 1:3 ratio shaft providing two strokes of a piston
to 360 degrees of output shaft rotation. The same as a
conventional engine.
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