Internal combustion barrel engine

A two-stroke barrel engine includes a power output shaft configured to rotate, an even number of cylinders encircling the power output shaft, wherein each cylinder includes opposing first and second power pistons configured to reciprocate within their respective power cylinder, and a pair of non-rotating wobbleplates opposed and hingedly connected to the power pistons. The wobbleplates are configured to transfer the reciprocating motion of the power pistons to rotary motion of the power output shaft via a nutating motion of the non-rotating wobbleplate.

FIELD OF THE INVENTION

The present invention relates generally to internal combustion engines, and more specifically to a two stroke barrel engine.

BACKGROUND

A barrel engine is a type of reciprocating engine that replaces the common crankshaft with a circular plate (the swashplate). Pistons press down on a circular plate in a circular sequence, forcing it to nutate around its center. The plate, also known as a wobble plate, is typically geared to produce rotary motion.

Barrel engines are differentiated from other engines in that the cylinders are arranged in parallel around the edge of the plate, and possibly on either side of it as well, and are aligned with the output shaft rather than at 90 degrees as in crankshaft engines. This design results in a very compact, cylindrical engine, ideally suited for use in aircraft engines.

DETAILED DESCRIPTION

FIG. 1illustrates a longitudinal view and an end view of a barrel engine100according to one embodiment. The engine100features a two stroke barrel arrangement that includes a frame, i.e., cylinder block25, that houses an even number of cylinders encircling a power shaft13, wherein the centerlines of all the cylinders are parallel to each other. The cylinders operate in pairs, wherein each pair of cylinders comprises the two cylinders on opposite sides of power shaft13. Engine100further includes a wobbleplate drive system that includes two non-rotating wobbleplates9, each mounted on opposite ends of cylinder block25.

Each cylinder comprises a power cylinder comprising power sleeve3and a stepped charging cylinder comprising stepped sleeve4. Disposed within each power cylinder are opposing piston1and2. At a top stroke, a piston position encloses minimum cylinder volume; at a bottom stroke a piston position encloses maximum cylinder volume. Piston1is a power piston whose reciprocating motion drives power shaft13. Piston2, however, includes both a power piston and a stepped charging piston portion.

The cylinders operate in pairs opposite each other, wherein the stepped charging piston portion of piston2compresses inlet air to charge the two stroke power cylinder of the opposing paired cylinder.

At opposite ends of the power cylinder and at the bottom of the stroke, one of the power pistons1actuates an inlet port8band the stepped power piston2actuates an exhaust port. The ports are configured such that exhaust port8aopens slightly before inlet port8b. On the opposite side of wobbleplate9, stepped piston2opens an inlet port6from the carburetor at the bottom of it's stroke. At the top of it's stroke there is an always open outlet port5leading into a transfer passage7that connects with inlet port8bof the power piston it pressurizes.

The stepped piston2pressurizes the inlet air to charge the power cylinder of its paired cylinder. When the power piston's inlet port8bhas opened for inlet, at the bottom of the stroke, the stepped piston2opposite is at the top of it's stroke, having compressed the fuel/air mixture.

The stepped charging piston2of one cylinder pressurizes the power cylinder of its paired cylinder. Accordingly, each stepped piston2moves in the opposite direction from its paired power piston1. The stepped piston can be large enough to produce more piston displacement than the power piston's displacement producing excess air for supercharging.

Intake port5is an input to the power cylinder by transfer passage7, and the stepped charging cylinder comprises intake port6from a carburetor. Transfer passage7connects the charging cylinder to a port8bof the power cylinder. The cylinder block further includes two split radial shaft main bearings18, a cooling water jacket21, a starter ring gear22, an accessory drive gear23, end housings24, a split bore26in cylinder block25to assemble power shaft13into it's main bearings, spark plug bore27, a shaft thrust bearing17, and an oil feed bearing29.

The pistons disposed within each power cylinder include a power piston1and a combination power piston and stepped charging piston2. Connecting rods14connect each piston1,2to wobbleplates9via carden type two-pin universal joints at both ends of the connecting rod14. Because all of the pins handle the same load, the diameter of the pins is determined by the diameter of the piston wrist pins. Unlike a crankshaft connecting rod that experiences a violent lateral oscillation due to rotation of the crank, the connecting rods14do not need to be of the strong I-beam shape of crankshaft connecting rods. Accordingly, in one embodiment, connecting rods14are comprised of lightweight tubes having thick ends, the ends flattened and bored, wherein the hole for the pin goes through the thicker part of the flattened rod end. No welding or riveting is required.

As disclosed herein, wobbleplate9eliminates the need of piston rollers of previous wobbleplate designs and is designed according to a fatigue life determined by factors including the material used, stress in the shaft, and the number of its cycles experienced in its lifetime. Stress is based upon the value of the bending moment, caused by the spread of main bearings18between wobbleplates9and the offset of the connecting rods14from the shaft center and the number of cycles experienced. The greater the bearing spread, the higher the bending moment value.

Wobbleplates9are restricted from rotating and receive force from each piston1,2equally spaced around the periphery of wobbleplate9by a connecting rod14having swiveled ends that cause wobbleplate9to wobble, thereby transferring the piston's reciprocating motion into rotary motion of power shaft13.

Each wobbleplate9is mounted via wobbleplate mounting bearing10to a slug11with a skewed bore, and is configured to transfer reciprocating motion from pistons1,2into rotary motion of power shaft13passing through slug11. Pin12secures slug11to power shaft13. Connecting rod14includes hinged ends mounted to hinged double pin carden joints. The hinged connection15of wobbleplate9to the connecting rod14allows angular motion of connecting rod14at the wobbleplate9. Hinged carden joint16includes a piston wrist pin.

Wobbleplates9are non-rotating. In the embodiment illustrated inFIG. 1, anti-rotator rod19is fixed to, and extends radially from, the periphery of each wobbleplate9. Non-limiting, wobbleplate9is prevented from rotating by a pair of fixed planar members20straddling the anti-rotator rod19, the straddling members lying in planes parallel to the centerline of power shaft13and anchored to frame25of engine100. As wobbleplate9rocks, anti-rotator rod19slides always parallel to the centerline of power shaft13preventing wobbleplate9from rotating.

FIG. 2illustrates another embodiment of an anti-rotator device wherein rotation of each wobbleplate9is prevented by a rotatable yoke29having at least one of its ends pivoted 90 degrees around a rotation restraint pin31mounted to the outside of wobbleplate9, and at least one other end of yoke29connected to frame25via attachment pin30. Rotation restraint pin31is configured to swivel into yoke29, allowing yoke29to rotate, while preventing the rotation of wobbleplate9.

Rotation restraint pin31, mounted to the periphery of wobbleplate9, oscillates, following the angle of wobbleplate9twice every revolution of shaft13as pin31slides back and then forth with the wobble. Furthermore, rotation restraint pin31carries the load of wobbleplate9from connecting rods14. Accordingly rotation restraint pin31is preferably lubricated by the surrounding load-carrying bushings.

In one embodiment, shaft13is hollow and contains oil under pressure. A groove disposed all the way around the inside of bearing29allows oil to flow from skewed slug11through wobbleplate9to rotation restraint pin31or anti-rotator rod19.

In an alternate embodiment, a non-wobbling oil disc28is mounted on power shaft13between the wobbleplate9and the cylinder block. Unlike oil being dispersed from wobbleplate9, non-wobbling oil-disk28has an advantage of directing oil into the cylinders with greater accuracy without squirting oil in a trajectory determined by the wobble.