Toyota Jidosha Kabushiki Kaisha

Yuji Yoshihara

Hiromasa Suzuki

Hiroyuki Kawase

Yuichi Sakaguchi

Yoshihito Moriya

Senji Kato

Nobuhisa Ohkawa

Tadahisa Naganawa

Yoshiya Yamashita

Koichi Shimizu

Shigeru Sone

Hitoshi Uda

Kouichi Shimizu

A valve performance control apparatus has a low speed cam, a high speed cam, and an intermediate speed cam. A rocker arm is arranged between the cams and a valve. The rocker arm contacts the low speed cam. A pair of cam followers are reciprocally supported in the rocker arm to contact the high speed and intermediate speed cams. Lock members are slidably received in bores (or grooves) of the rocker arm. The lock members, when positioned in an unlocked position, permit the free reciprocation of the associated cam followers with respect to the rocker arm, which causes the valve to be driven by the low speed cam. When locked, the lock members abut against the associated cam followers and lock the cam followers to the rocker arm, which causes the valve to be driven by the cam with the largest profile. The lock member has an abutment surface, which contacts and is pressed by the cam follower. The bore has a supporting wall for supporting the lock member opposite to the abutment surface when the abutment surface of the lock member is positioned in the lock position and is pressed by the cam follower. The lock member is not subjected to bending or shear, which improves the reliability of the apparatus.

Valve performance control apparatus for internal combustion engines

There is disclosed a valve performance controller for an internal combustion engine. A camshaft is provided with a plurality of cams having different cam profiles. Changeover of the cams is performed through operation of a valve lift control mechanism. Also, a valve timing control mechanism is provided on the camshaft. The valve timing mechanism has a pulley, which is connected to a crankshaft of the engine via a timing belt. The pulley is connected to the camshaft via a ring gear. Through movement of the ring gear along the axis of the camshaft, the relative rotational phase between the pulley and the camshaft is changed. At least during cam changeover operation, oil is charged and retained within the hydraulic chamber located on both sides of the ring gear in the moving direction thereof. This structure reduces an impact which acts on the timing belt upon changeover of the cams.

Valve performance controller for internal combustion engine

An improvement of a valve timing control apparatus for an engine is disclosed. The apparatus has an intake valve and an exhaust valve which are alternately opened and closed in a valve timing sequence according to a rotation of a cam shaft. A timing pulley mounted on the cam shaft has a housing accommodating a plunger movable therein and a sleeve secured to the cam shaft. The housing has a first and second pressure chambers defined by the plunger and sealed with respect to each other. The plunger is arranged to move in an axial direction to selectively advance and retard the cam shaft based on differential pressure between the first pressure chamber and the second pressure chamber. A controller controls an electromagnetic valve with a specific control value to adjust the fluid pressure to be supplied to the first and second pressure chambers to maintain the valve timing sequence converged to a target valve timing. The controller corrects the specific value based on a rotational speed of the engine when the plunger is in one of the extreme positions in the chambers, and adjusts the fluid pressures based on the corrected specific value.

Valve timing control apparatus for engine

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Toyota, Japan

Yuji Yoshihara