IC Engine with NO Crankshaft

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Planetary gear-sets can be incorporated in the design of an IC engine by replacing the conventional style crankshaft. This concept could be used in IC engines of all sizes, two or four stroke, gas or diesel, the only stipulation being, in its simplest form, the architecture be that of a “boxer” opposed cylinder configuration.

The mechanism's principal benefit is to provide the piston with a connecting rod attachment that eliminates ALL angular thrust between the piston and cylinder wall. Additionally, engine designs would no longer require the fabrication of a forged, cast or billet crankshaft to provide drive to the output shaft.

The attached video is of a proof-of-concept prototype engine. The base engine concept is that of a common-axis, two cylinder module incorporating the cylinders, cylinder heads and pistons of a two-stroke Kawasaki 340 engine. By using a number of commercially available spur gears and bearings a “gear-case” with a 2.0-in. stroke was designed to operate with the 2.36-in. bore of the donor engine.

The pair of planetary gear-sets, with the annulus gears held stationary, are connected through a ball bearing mounted linkage to an opposing pair of planet gears. The linkage carries a linear bearing attached to a shuttle assembly whose motion is then defined by an additional pair of linear bearings traveling on fixed parallel shafts. The shuttle assembly carries the connecting rods and pistons.

This mechanism allows the purely linear motion of the pistons and connecting rods to be converted to a rotary motion drive shaft connected to a center mounted sun gear. As demonstrated in the video the drive shaft could instead be connected directly to the planet carrier, rather than the sun gear, to provide one revolution of the output shaft for each one cycle of the pistons.

Additional two cylinder modules could be ganged together to achieve increased capacity. Each
added module would require ONE additional planetary gear-set.



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  • Name:
    Mike Trost
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    Team members:
    Mike Trost
    Randy Tetzlaff
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