| 摘要 |
1299673 I. C. engine valve gear FIAT SpA 29 Jan 1970 [13 Feb 1969] 4369/70 Heading F1B [Also in Division F2] In a valve operating mechanism including a rocker 17 operated from a rotary shaft 12 and having a cam surface 18 formed of a section 20 concentric with the rocker axis and a valve lift section 21, the cam surface acts on a rocking member 23 and the valve lift opening period and timing are conjointly adjustable. In the embodiment shown, the rocker 17 is operated by an eccentric 13 on the shaft 12 through a connecting rod 15 and the shaft 24 of the member 23 is angularly adjustable about the rocker shaft 19 by lubricating oil under pressure supplied to a cylinder 27 in a member 26 supporting the shaft 24. The cylinder 27 contains a piston 28 reacting against a fixed surface 30 in the engine cylinder head 11'. A valve 34 in the oil supply line 32a to the cylinder 27 is controlled by a centrifugal governor 37, which also controls the valve inlet pressure, and a capsule 38 which is subject to the engine intake manifold vacuum. The radius of curvature of the valve stem operating surface 25 of the member 23 may be on the axis of the shaft 19 when the valve is closed or displaced therefrom to provide for variation in clearanel in the mechanism with adjustment of valve lift. In this embodiment separate shafts 12 are provided for the inlet and exhaust valves, Fig.1 (not shown). In a further embodiment, Figs.5 and 6 (not shown), a rotary shaft 12 in the engine cylinder block 1 operates overhead inlet and exhaust valves through respective eccentrics 13, connecting rods 15 and rockers 17. The shafts 24 of the members 23 are mounted in respective arms (47) pivoted at one end on the respective rocker shaft 19 and having at the other ends nose portions (48) which contact respective downwardly sloping top faces (54, 55) on a piston (50) of an hydraulic actuator (51). In another embodiment, Fig.8 (not shown), the eccentrics 13 are coupled to the rockers 17 by respective pairs of connecting rods (15,62). The pairs of rods are connected by respective bellcrank levers (58) mounted on a shaft (59) coupled by an arm (64) to one of the rocker shafts 19. The bell-crank lever shaft (59) is adjustable by a piston hydraulic actuator. In a final embodiment, Fig.9 (not shown), the inclined in-line inlet and exhaust valves are actuated from a respective eccentric 13 connecting rod 15, rocker 17 and a member 23 having one end contacting the valve stem and the other end co-operating with the cam surface 18. 'The rocker shaft 19 is mounted in an arm (69), pivotally mounted on a shaft (70), for angular adjustment by an hydraulic piston actuator. The end of the member 23 co-operating with the cam surface 18 has an arcuate surface (66) with its axis of curvature on the axis of the shaft (70) of the arm (69) mounting the rocker shaft 19 when the valve is closed. |
