Abstract: A rocker arm that is rockably attached to a cylinder head actuates a valve by a guide groove that is formed at an end thereof engaging with an upper end of a valve stem, and a roller that is mounted in a roller housing portion of the arm main unit contacting against a cam and rocking. The guide groove is formed by press working ends of the arm main unit in the thickness direction of the plate material to form a pair of walls, and thereafter applying sandwiching pressure in the lateral direction to the walls to increase the height thereof.

Abstract: A lash adjuster includes a plunger and a cylinder. The cylinder includes a high-pressure chamber defined therein. The plunger has a valve port provided through a bottom wall thereof. The valve port includes a seat. A spherical valve body is accommodated in the high-pressure chamber. The valve body is made of ceramic material containing silicon nitride. The valve body is arranged to have a surface roughness average (Ra) of equal to or less than 0.13 ?m. The valve body is arranged to have a contact pressure of equal to or lower than 1386 Mpa with the seat in a state where the valve port is closed by the valve body.

Abstract: A return spring 35 is formed using a compression coil spring that is installed so that its axial direction is an up-down direction. The return spring 35 is provided in a high-pressure chamber 14, and powers a plunger 20 in an upwards direction. A coil diameter of the return spring 35 varies along the axial direction. When the return spring 35 is in a maximally compressed state, an axial direction dimension (up-down direction dimension) is smaller than a dimension that is a thickness of a spring wire 36 multiplied by the number of coil turns. Hence, an overall height of a lash adjuster A can be reduced in comparison to when a return spring with a constant coil diameter over an entire length is used.

Abstract: A rocker arm 6 that is rockably attached to a cylinder head 1 actuates a valve 4 by means of a guide groove 73b that is formed at an end thereof engaging with an upper end of a valve stem 41, and a roller 8 that is mounted in a roller housing portion 72 of the arm main unit 7 contacting against a cam 31 and rocking. The guide groove 73b is formed by press working ends of the arm main unit 7 in the thickness direction of the plate material to form a pair of walls 73d, and thereafter applying sandwiching pressure in the lateral direction to the walls 73d to increase the height thereof.

Abstract: The current invention provides an inexpensive variable valve mechanism that includes a first intervening member which rotates a small angle rotation about an axis of a support shaft by being pressed by a rotating cam and a second intervening member which lifts a valve by making a small angle rotation about an axis of the support shaft together with the first intervening member thus pressing a cam corresponding part of a rocker arm.

Abstract: The current invention provides an inexpensive variable valve mechanism that includes a first intervening member which rotates a small angle rotation about an axis of a support shaft by being pressed by a rotating cam and a second intervening member which lifts a valve by making a small angle rotation about an axis of the support shaft together with the first intervening member thus pressing a cam corresponding part of a rocker arm.