Compact engine packs a powerful punch

Nov. 6, 2012
Paul Karlan first thought up his Karlan Cam Engine for surface vehicles about 50 years ago when he was trying to figure out a different way to change the reciprocating motion of pistons to rotary motion.

Paul Karlan first thought up his Karlan Cam Engine for surface vehicles about 50 years ago when he was trying to figure out a different way to change the reciprocating motion of pistons to rotary motion. Instead of using a crankshaft, his engine uses two cams attached to the output shaft. The engine has four cylinders, two banks of two cylinders each, parallel to the output shaft. Both the opposite cylinders fire every 180º (both sides), for four cycles/rev, as opposed to a crankshaft engine, which is two cycles/rev. A disc valve is keyed to the output shaft between the two cylinder banks. The disc valve meters the four cycles in and out of the cylinders. The pistons connect to the connecting plate which rides on the cams. The cam lobes are tapered to provide true rolling motion between the cam followers and the cam. The connecting plates on each side of the cylinder blocks reciprocate equal and opposite to each other, giving balanced motion.

According to Karlan, his barrel engine is the only one with two cams and four cylinders. The only other barrel engine he knows about — the Hermann engine — has one cam that sits in the center of the output shaft, and two banks of six cylinders on each side of the block. The Hermann engine design has disadvantages, says Karlan. It uses poppet valves, which have intake/exhaust overlap. The Karlan engine has a disc valve with little intake/exhaust overlap. The clearance between the disc valve and the cylinder heads in the Karlan engine is just a couple of tenths. This minimal clearance is maintained by “floating seals“ — i.e., the thin layer of air — so there is no friction and almost no compression leakage. This patented feature has been well tested in the running prototypes.

Another advantage pertains to side pressure, says Karlan. Piston side pressure on the side of the cylinder wall is what turns the output shaft on the power stroke. The connecting plates on the Karlan engine reciprocate on bronze bushings with hardsurfaced, lubricated guide rods, which take all the side pressure, with little sliding friction. And, there is no side pressure on the pistons. True, a significant weight goes back and forth, but the momentum of the reciprocating plate goes into the flywheel, says Karlan. The only energy lost is in the friction of the slides and there is little friction. His special cam followers have high-speed, heavy-duty radial and thrust bearings mounted in an aluminum housing (not needle bearing cam followers). His engine output shaft, thus, provides low rpm with high torque.

In addition, the length of the connecting rod determines the compression ratio. Users can, thus, adjust the compression ratio. Karlan believes his engine is more efficient than current designs because it entails almost no intake/exhaust overlap and less internal sliding friction. Although the working prototype has not yet been tested for extended operation, Karlan says it shows no inherent weak spots, and is a sturdy mechanism.

The Karlan Cam Engine is running on a bench with the “cam-case” panels removed to show the mechanism. Ordinarily, this would be enclosed for the lubrication system, as it is in the Karlan Car.The Karlan Cam engine has a low and long configuration which could apply to aircraft and more. Karlan feels his engine could be an alternate to the polluting turbojet engine, which many scientists link to global warming. Propulsion could be by ducted fan or gasoline electric.

The engine can have pistons with small or large diameters, up to 10 in. or more. Karlan’s prototype engine, which is running on gasoline on a bench, shown at, has 2½-in. bores. The Karlan Cam Engine Car, shown at, has 3 1”/8•-in. bores.

The Karlan engine has relatively few parts. It has no gears, no timing belts, no springs, and no gaskets. The engine can be air or water cooled. The Karlan Car was water cooled and had a pressurized lubrication system. Karlan plans on applying several improvements, including a special supercharger. Karlan can be reached at [email protected].

© 2012 Penton Media, Inc.

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