Abstract: A drive force transmission mechanism includes: a sprocket attached to a camshaft; a timing chain meshing with the sprocket and transmitting a drive force of a crankshaft to the camshaft; and a guide unit facing the timing chain, wherein the guide unit is located within a mesh zone where the timing chain and the sprocket mesh with each other, is not located in a zone other than the mesh zone, and has a length at least equal to a length of one link of the timing chain

Abstract: In an engine valve, a first sliding area formed at a valve head side in an outer face of a valve stem, and sliding along a stem guide, a second sliding area formed at an opposite side from the valve head side, and sliding along the stem guide, and a first small diameter area formed between the first sliding area and the second sliding area are formed. Further, in the engine valve, a length, in an axial direction of the valve stem, of the first sliding area abutting on the stem guide at a position where the engine valve is fully opened is longer as compared with a length, in the axial direction of the valve stem, of the second sliding area abutting on the stem guide at a position where the engine valve is fully closed.

Abstract: An adjustable valve device includes: a first cam portion penetrated by a camshaft, rotating with the camshaft, and including an elongated hole formed therein; a U or L shaped second cam portion supported by the first cam portion so as to swing to move between a first state and a second state; a stopper pin fixed to the second cam portion and penetrating through the elongated hole; a biasing member biasing the stopper pin so that the second cam portion becomes in the first state; a lock mechanism locking the second cam portion only when the second cam portion is in the first state; and a cam follower exerting a reactive force so that the second cam portion becomes in the second state in a state where a lock of the second cam portion is released, wherein the reactive force is greater than a biasing force of the biasing member.

Abstract: A valve mechanism includes: a support shaft immovably fixed to a main body of an internal combustion engine, a main arm swingably supported by the support shaft; two sub-arms arranged at both sides of the main arm; a coupling support portion swingably supporting and coupling the two sub-arms to the main arm; a cam; and a roller rotatably located in the main arm. Each of the two sub-arms includes: a drive unit pressing and driving a valve; and a contact portion contacting a plunger of a lash adjuster, the contact portion has a curved surface slidably contacting a flat surface formed in a tip portion of the plunger and having an arc-like curved surface shape of which a central axis line corresponds to a central swing axis line of the main arm in a state where the cam abuts on the roller in a base circular portion of the cam.

Abstract: In an engine valve, a first sliding area formed at a valve head side in an outer face of a valve stem, and sliding along a stem guide, a second sliding area formed at an opposite side from the valve head side, and sliding along the stem guide, and a first small diameter area formed between the first sliding area and the second sliding area are formed. Further, in the engine valve, a length, in an axial direction of the valve stem, of the first sliding area abutting on the stem guide at a position where the engine valve is fully opened is longer as compared with a length, in the axial direction of the valve stem, of the second sliding area abutting on the stem guide at a position where the engine valve is fully closed.

Abstract: An adjustable valve device includes: a first cam portion penetrated by a camshaft, rotating with the camshaft, and including an elongated hole formed therein; a U or L shaped second cam portion supported by the first cam portion so as to swing to move between a first state and a second state; a stopper pin fixed to the second cam portion and penetrating through the elongated hole; a biasing member biasing the stopper pin so that the second cam portion becomes in the first state; a lock mechanism locking the second cam portion only when the second cam portion is in the first state; and a cam follower exerting a reactive force so that the second cam portion becomes in the second state in a state where a lock of the second cam portion is released, wherein the reactive force is greater than a biasing force of the biasing member.

Abstract: A valve mechanism includes: a support shaft immovably fixed to a main body of an internal combustion engine, a main arm swingably supported by the support shaft; two sub-arms arranged at both sides of the main arm; a coupling support portion swingably supporting and coupling the two sub-arms to the main arm; a cam; and a roller rotatably located in the main arm. Each of the two sub-arms includes: a drive unit pressing and driving a valve; and a contact portion contacting a plunger of a lash adjuster, the contact portion has a curved surface slidably contacting a flat surface formed in a tip portion of the plunger and having an arc-like curved surface shape of which a central axis line corresponds to a central swing axis line of the main arm in a state where the cam abuts on the roller in a base circular portion of the cam.

Abstract: A variable valve operating apparatus includes a drive camshaft that is rotationally driven by the rotational force of the crankshaft, and a driven cam lobe that is rotatably supported by the drive camshaft. The variable valve operating apparatus further includes a guide member that has a raceway surface formed so as to surround the drive camshaft. The variable valve operating apparatus further includes a link mechanism that is connected to each of the drive camshaft and the driven cam lobe and has a control roller which is in contact with the raceway surface. The variable valve operating apparatus further includes a link plate and holding rollers that maintain contact between the raceway surface and the control roller while the drive camshaft makes one rotation. The variable valve operating apparatus further includes an actuator that drives the guide member.

Abstract: A variable valve operating apparatus includes a drive camshaft that is rotationally driven by the rotational force of the crankshaft, and a driven cam lobe that is rotatably supported by the drive camshaft. The variable valve operating apparatus further includes a guide member that has a raceway surface formed so as to surround the drive camshaft. The variable valve operating apparatus further includes a link mechanism that is connected to each of the drive camshaft and the driven cam lobe and has a control roller which is in contact with the raceway surface. The variable valve operating apparatus further includes a link plate and holding rollers that maintain contact between the raceway surface and the control roller while the drive camshaft makes one rotation. The variable valve operating apparatus further includes an actuator that drives the guide member.