Rocker arm and method of manufacturing same
AssigneesOtics Corporation, Nakanishi Metal Works Co., Ltd.
InventorsNaoki Hiramatsu, Akira Takeuchi, Kimihiko Todo, Tomiyasu Hirano, Yoshio Kawatake
Life of this patent
Estimating the term…
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.
Claims10
A method of manufacturing a rocker arm comprising the following steps, wherein the rocker arm is a cold-formed rocker arm of a cam follower type that is attached to a cylinder head of an internal combustion engine, has a guide groove that accepts a top end of a valve stem of the internal combustion engine, and rocks to actuate a valve of the internal combustion engine:
- a punching step that punches a plate material into a predetermined shape having a pair of side edges;
- a press step that forms an initial groove having an opposing pair of guide walls by depressing the punched plate material by a predetermined amount in a thickness direction thereof by pressing a punch against the plate material;
- and
- a sandwich pressure step that increases heights of the pair of guide walls by applying sandwiching pressure to the guide walls in a direction from the outside toward the inside using a sandwich pressure punch (the guide groove is defined between the pair of guide walls).
A rocker arm that is a cold-formed rocker arm of a cam follower type that is attached to a cylinder head of an internal combustion engine having a valve stem, comprising the following elements:
- a metal arm main unit that includes a first edge and a second edge;
- a rocking support that is formed at the first edge side of the arm main unit;
- and
- a pair of guide walls that are formed at the second edge side of the arm main unit (these guide walls are formed in the main unit by pressing a punch against the main unit in the thickness direction thereof to depress the main unit by a predetermined amount to form an initial groove that is surrounded by a pair of walls, and thereafter increasing heights of the walls by applying sandwiching pressure to the walls in a direction from the outside toward the inside using a sandwich pressure punch);
- and wherein a guide groove that accepts an upper edge of a valve stem of the internal combustion engine is formed between the guide walls, and the arm main unit rocks to actuate a valve of the internal combustion engine.
Dependencies are inferred from the claim text.