| 摘要 |
Two arms (14, 15) are articulated to one another about a pivot (16) integral with the engine (1). A first roller (18) fixed to the arm (15) interacts with the conducting strand (32) of the toothed belt (9), located between the crankshaft pulley (7) and the intake camshaft pulley (5), and a second roller (19) carried by the arm (14) acts on the strand (33) located between the pulley (5) and the pulley (4) of the exhaust valves. The displacement of the rollers (18 and 19) takes place by virtue of a motor (25) driving a threaded rod (28) engaged in a nut (29) mounted pivotably on the arm (14). The angle of opening between the two arms (14 and 15) may be adjusted manually or automatically. The belt (9) is tensioned by a tensioning roller (11). The motor (25) is subjected to a control (31) which is sensitive to the speed of the engine (1). The instants at which the valves are opened and closed can thus be varied without changing the duration of their opening. <IMAGE>
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