Valve operating mechanism

Claim 2

A valve operating mechanism for operating a pair of valves of an internal combustion engine, comprising: a camshaft having a plurality of cams; a plurality of rocker arms held in sliding contact with said cams, for operating the valves according to the cam profiles of said cams; and means for selectively interconnecting and disconnecting said rocker arms to operate the valves at different valve timings in low-, medium-, and high-speed ranges of the engine.

Claim 3

A valve operating mechanism according to claim 1, wherein said cams include a low-speed cam and a high-speed cam having a cam lobe larger than the cam lobe of said low-speed cam, said camshaft also having a circular raised portion corresponding to a base circle of said low and high-speed cams, said high-speed cam being disposed between said low-speed cam and said raised portion, said rocker arms including first, second, and third rocker arms slidably held against said high-speed cam, said low-speed cam, and said raised portion, respec­tively, and said second and third rocker arms having ends for engagement with said intake valves.

Claim 4

A valve operating mechanism according to claim 2, including lifter means for normally urging said first rocker arm resiliently into sliding contact with said high-speed cam.

Claim 5

A valve operating mechanism according to claim 1, wherein said cams include a low-speed cam and a high-speed cam having a cam lobe larger than the cam lobe of said low-speed cam, said camshaft also having a circular raised portion corresponding to a base circle of said low- and high-speed cams and disposed between said low-speed cam and said high-speed cam, said rocker arms including first, second and third rocker arms slidably held against said raised portion, said low-speed cam, and said high-speed cam, respectively, said first and second rocker arms having ends for engagement with said intake valves.

Claim 6

A valve operating mechanism according to claim 4, including lifter means for normally urging said third rocker arm resiliently into sliding contact with said high-speed cam.

Claim 7

A valve operating mechanism according to claim 1, wherein said cams include a first low speed cam, a second low-speed cam having a cam lobe of a different profile from the profile of the cam lobe of said first low-speed cam, and a high-speed cam having a cam lobe larger than the cam lobes of said first and second low-speed cams and disposed between said first and second low-­speed cams, said rocker arms including first, second, and third rocker arms slidably held against said high-speed cam, said first low-speed cam, and said second high-speed cam, respectively, said first and third rocker arms having ends for engagement with said intake valves.

Claim 8

A valve operating mechanism according to claim 6, including lifter means for normally urging said first rocker arm resiliently into sliding contact with said high-speed cam.

Claim 9

A valve operating mechanism according to any preceding claim, wherein said interconnecting and disconnecting means comprises a first selective coupling operatively disposed in and between said first and second rocker arms for selectively inter­ connecting and disconnecting the first and second rocker arms, and a second selective coupling operatively disposed in and between said first and third rocker arms for selectively interconnecting and disconnecting the first and third rocker arms, said first and second selective couplings being operable independently of each other.

Claim 10

A valve operating mechanism according to claim 8, wherein said first selective coupling comprises a first guide bore defined in said first rocker arm, a second guide bore defined in said second rocker arm in registration with said first guide bore, a first piston slidably fitted in said first guide bore, a first spring disposed in said second guide bore for normally urging said first piston into said first guide bore, and first means for applying hydraulic pressure to said first piston to move the same to a position between said first and second guide bores against the resiliency of said first spring, and wherein said second selective coupling comprises a third guide bore defined in said first rocker arm, a fourth guide bore defined in said third rocker arm in registration with said third guide bore, a second piston slidably fitted in said third guide bore, a second spring disposed in said fourth guide bore for normally urging said second piston into said third guide bore, and second means for applying hydraulic pressure to said second piston to move the same to a positon between said third and fourth guide bores against the resiliency of said second spring.

Claim 11

A valve operating mechanism for operating a pair of valves of an internal combustion engine, comprising: a camshaft having a pluatlity of cams of different cam profiles, and means responsive to selective engagement with said cams for operating the valves at the same valve timing in a high-speed range of the internal combustion engine and for operating the valves at different valve timings in a speed range other than said high speed range.

Claim 12

A valve operating mechanism for operating a pair of valves of an internal combustion engine, comprising: a camshaft having a pluatlity of cams of different cam profiles, and means responsive to selective engagement with said cams for operating the valves at the same valve timing in a high-speed range of the internal combustion engine and for operating the valves at different valve timings in a speed range other than said high speed range.