US 5,203,289 AGranted

Variable timing mechanism

AssigneeAtsugi Unisia Corporation

InventorsSeinosuke Hara, Shoji Morita, Yoshihiko Yamada

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Abstract

An apparatus for use in a variable valve timing and/or valve lift system of an internal combustion engine is disclosed. The apparatus is easy to mount, install and adjust within a space available over a cylinder head of the engine. The apparatus comprises a rocker shaft, a first cam, a second cam, and a rocker arm pivotally mounted on the rocker shaft. The rocker arm includes a first cam follower arranged to engage the first cam and a second cam follower arranged to engage the second cam. The second cam follower is pivotally mounted on the rocker arm. A hydraulically operated locking bolt is movable from an unlocking position to a locking position. In the locking position, the locking bolt is received in bores formed in the rocker arm and in the second cam follower to establish a positive motion state wherein the rocker arm moves with said second cam follower as a unit. A mechanism includes a timing lever and restrains the locking bolt against at least moving out of the unlocking position to the locking position.

An apparatus comprising:

a rocker shaft;
a first cam;
a second cam;
a rocker arm pivotally mounted on said rocker shaft, said rocker arm including a first cam follower arranged to engage said first cam,
said rocker arm including a second cam follower, said second cam follower being arranged to engage said second cam;
means for connecting said second cam follower to said rocker arm for a unitary motion, said connecting means having a positive motion state wherein said rocker arm moves with said second cam follower as a unit as said second cam follower follows said second cam and a lost motion state wherein said rocker arm fails to move as a unit with said second cam follower, said connecting means being shiftable between said positive motion state and said lost motion state;
wherein said connecting means includes a first bore formed in said rocker arm, a second bore formed in said second cam follower, a hydraulically operated locking bolt received in said first bore to define therein a hydraulic chamber, said locking bolt movable between an unlocking position wherein said locking bolt is disengaged from said second bore and a locking position wherein said locking bolt is inserted into said bore, and means for resiliently biasing said locking bolt toward said unlocking position;
means for mechanically restraining said connecting means at least against shifting out of said lost motion state toward said positive motion state;
and
wherein said mechanically restraining means includes a groove formed in said rocker shaft and having a bottom wall, a timing lever mounted on said rocker arm and having a follower portion in engagement with said bottom wall, a spring arrangement for biasing said timing lever in a first direction to maintain said follower portion of said timing lever in engagement with said bottom wall and biasing said timing lever in a second direction, a piston receiving bore formed in said rocker arm, a hydraulically operated piston received in said piston receiving bore and defining therein a second hydraulic chamber, said hydraulically operated piston being arranged to engage said timing lever and subject to a bias of said spring arrangement in said second direction.

7 more elements

Abstract

Claims35