Knight engine

The Knight engine was an internal combustion engine, designed by American Charles Yale Knight (1868-1940), that used sleeve valves instead of the more common poppet valve construction.

While eventually these engines were manufactured in the largest quantities in USA, Knight's design was made a commercial success by development in England. The French gave the Knight engine more intensive development than any other nation. Ultimately Knight patents were issued in at least eight different countries and were actually built by about thirty firms.

Born in Indiana in 1868, Knight was originally a printer and newspaper publisher, publishing a Midwest farm journal called Dairy Produce. To cover dairy activities during 1901-02, he bought an early Knox automobile, a three-wheeler with an air-cooled, single-cylinder engine whose noisy valves annoyed him. He believed that he could design a better engine and proceeded to do so. Knight was familiar with the slide valves used on early Otto engines, having repaired the similar valve mechanism in his father's sawmill. The slide valve had, however, been replaced in gasoline engines by the poppet valve, whose characteristics were better suited to four-stroke engines.

At first Knight tried making the entire engine cylinder reciprocate to open and close the exhaust and inlet ports. Though he patented this arrangement, he soon abandoned it in favor of a double sliding sleeve principle. Backed by Chicago entrepreneur L.B. Kilbourne, an experimental engine was built in Oak Park, Illinois in 1903. Research and development continued until 1905, when a prototype passed stringent tests in Elyria, Ohio. Having developed a practicable engine (at a cost of around $150,000), Knight and Kilbourne showed a complete "Silent Knight" touring car at the 1906 Chicago Auto Show. Fitted with a 4-cylinder, 40 hp (30 kW) engine, the car was priced at $3,500.

Knight's design had two cast-iron sleeves per cylinder, one sliding inside the other, with the piston inside the inner sleeve. The sleeves were operated by small connecting rods actuated by an eccentric shaft and had ports cut out at their upper ends. The cylinder head (known as the "junk head") was like a fixed, inverted piston with its own set of rings projecting down inside the inner sleeve. The heads were individually detachable for each cylinder. The design was remarkably quiet and the sleeve valves needed little attention. It was, however, more expensive to manufacture due to the precision grinding required on the sleeves' surfaces. Also it used more oil at high speeds and was harder to start in cold weather.

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