The first studies related to the rotary piston engine date back to 1920 (Umpleby) and reached an
application level in 1963 (NSU) with the construction of a car equipped with that engine.
The piston rotation with respect to the housing is driven by a pair of toothed wheels, one with
internal toothing integral with the piston, the other with external toothing integral with the housing.
The ratio of the number of teeth is equal to that between the number of rotor vertices and the
number of stator profile lobes.
It should be noted that all companies that have begun construction of Wankel engines have
chosen the type with two-lobes housing and three-lobes rotor
The stator profile is made up of an EPITROCHOID and the rotor profile is generated by the
internal envelope of the stator profile in its motion with respect to the rotor, considered fixed
The following conditions can be met, sufficient to generate properly dimensioned stator and rotor
profiles when known:
|
R : Radius of rotor
circumscribed circle.
Semi-Major Axis = R + e
Semi-Minor Axis = R – e
Radius of base circumference
a = ( 2 * R ) / 3
Radius of generating
circumference b = R / 3
|
a : Radius of base
circumference.
Radius of generating
circumference b = a / 2
Radius of rotor circumscribed
circle R = a + b
Semi-Major Axis = R + e
Semi-Minor Axis = R – e
|
b : Radius of generating
circumference.
Radius of base circumference
a = b * 2
Radius of rotor circumscribed
circle R = a + b
Semi-Major Axis = R + e
Semi-Minor Axis = R – e
|
The transmission ratio of mechanism is : RS / RS1 = ( N – 1 ) /N
In the Wankel motor, the movement is obtained by replacing the RS circumference with an
external toothed gear with primitive-radius=RS , and RS1 with an internal gear with primitive-radius=RS1 .
In the simulation, the stator remains stationary, the rotor rotates within the stator by moving its
zero on the circumference with a radius equal to eccentricity.
The rotor has three planetary revolutions around its zero for each turn of the crank, represented
by the eccentric e.
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