1. Field of Invention
The present invention relates to a variable valve lift apparatus, and more particularly, to a variable valve lift apparatus in which a latching portion connecting an inner body and an outer body is disposed adjacent to a cam, and a lost motion hinge shaft and a hinge point of the variable valve lift apparatus are disposed in the same direction relative to a camshaft.
2. Description of Related Art
In general, an internal combustion engine generates power by taking in fuel and air and burning it in a combustion chamber. Intake valves are operated by a camshaft in order to intake the air, and the air is drawn into the combustion chamber while the intake valves are open. In addition, exhaust valves are operated by the camshaft, and exhaust gas is expelled from the combustion chamber while the exhaust valves are open.
An optimal operation of the intake and exhaust valves depends on the rotation speed of the engine. That is, an optimal lift or optimal opening/closing timing of the valves depends on the rotation speed of the engine. In order to achieve such an optimal valve operation depending on the rotation speed of the engine, research has been undertaken for a variable valve lift (VVL) apparatus that includes a plurality of cams for driving the valves, or varies the lift of the valves depending on the number of rotations of the engine.
In a conventional variable valve lift apparatus, as shown in FIG. 10, a lost motion hinge shaft 40 connecting an outer body 10 and one side of an inner body 20 and a hinge shaft 60 of the variable valve lift apparatus are formed at the left and right of a camshaft.
FIG. 11a is a longitudinal cross-sectional view of the conventional variable valve lift apparatus in a latching operation, and FIG. 11b is a longitudinal cross-sectional view of the conventional variable lift apparatus in an unlatching operation. Conventionally, as shown in FIGS. 11a and 11b, the outer body 10 and the other side of the inner body 20 are connected by a latching mechanism 30 inserted into the outer body 10. Moreover, in an unlatching operation, the inner body 20 creates lost motion by a lost motion spring 50.
As the latching mechanism 30 is inserted into the outer body 10 as described above, the latching mechanism 30 becomes distant from the camshaft to thereby deteriorate the dynamic characteristics of the variable valve lift apparatus due to the moment of inertia. Also, a valve member is positioned under the lost motion spring 50, and such an apparatus has to press the valve member, thereby making the actual manufacture of the apparatus difficult.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.