From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Description of a rotary valve and its driving gear mechanism with reference to diagrams.
| Identifier | ExFiles\Box 147\4\ scan0175 | |
| Date | 13th August 1940 guessed | |
| be described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a section through a rotary valve and its driving gear, 5 Figure 2 is a section on the line 2-2 of Figure 1, and Figure 3 is a timing diagram for the mechanism. A valve 10 (Figure 1) is formed or carried 10 on a shaft 11 mounted in suitable bearings 12 and 13 and the shaft 11 carries a radial arm 14 by which it is driven. A gear-wheel 15 is mounted to rotate in a bearing 19 slightly eccentric from the shaft and is provided with a radial slot 16 in its under surface. A guide-block 17 is 15 capable of movement along the slot and is pivoted on a pin 18 on the radial arm 14. The wheel 15 is driven by any gearing 20 from the crankshaft, at half crankshaft speed and, therefore, its timing, or speed of rotation, is deter- mined by the crankshaft speed. The rotation of the wheel 15 20 rotates the valve 10, but owing to their relative eccen- tricities, the angular speed of the valve varies cyclically during each revolution by an amount determined by the radius r (see Figure 2) of the locus 20 of the pin 18 on the arm 14 and the eccentricity m of the arm 14 and wheel 15. If 25 ω is the angular velocity of the wheel 15, the minimum speed of the valve (its speed in the position shown in Figure 2) is (r-m) ω and its maximum speed (in the position shown dotted in Figure 2) is (r+m) ω so that the ratio of the maximum speed to the minimum speed is (r+m)/(r-m). In the 30 arrangement shown this ratio is 7/5. 4. | ||