Rocker arm for internal combustion engine

A valve mechanism of an internal combustion engine, comprising:

• a rocker arm main body, of which one end is rotatably supported by the engine's rocker shaft, and the other end forms an actuator to press the shaft-end of the intake valve or exhaust valve downward;
• and
• a roller rotatably supported by a roller pin in the middle part of said rocker arm main body, a camshaft being in contact with the roller from above in a slidable fashion,
• wherein a shaft passage is formed inside said rocker shaft, so that lubricating oil is supplied from the engine's oil pump through this shaft passage, and a bag-shaped oil sump is defined in said rocker arm main body, so as to contains said roller and roller pin and to open upwards;
• said rocker arm main body is provided with an entry hole to guide oil from said shaft passage into said oil sump, and an exit hole to supply oil from said oil sump by spraying near the shaft-end of an intake valve or exhaust valve, formed in said rocker arm main body;
• and
• wherein said oil level height of said oil sump is controlled by the height of the openings of said entry hole and said exit hole into said oil sump, and the height of said bottom end of said roller pin is lower than said oil level height so that at least the bottom end of said roller and roller pin is immersed in the oil in said oil sump.