Abstract: A hollow engine valve includes a shaft portion and an umbrella portion of which diameter is enlarged to form an umbrella shape to be provided on a base end of the shaft portion, a cooling material being enclosed in a hollow portion that is at least formed inside the shaft portion. The shaft portion comprises a first shaft portion in a tip end side, a second shaft portion that is provided in a base end side to have an outer diameter larger than that of the first shaft portion, and a stepped portion formed by a difference in the outer diameters between the first and second shaft portions. A wall thickness of the stepped portion is larger than that of the second shaft portion.

Abstract: An engine valve having a shaft portion and a head portion expanding in diameter like a head at an edge of the shaft portion, and being to open and close a port provided in a cylinder head, wherein the head portion has a head front surface on a bottom side facing a combustion chamber side, a head rear surface on a top side facing the port side, and an outer peripheral surface of the head portion formed between the head front surface and the head rear surface, and the head portion is provided a mirror-finished mirror portion, and the head portion is provided a mirror-finished mirror portion on the entire area of the head front surface exposed to the combustion chamber and the entire area of the outer peripheral surface exposed to the combustion chamber.

Abstract: There is provided a method of charging a hollow valve with metallic sodium easily and swiftly without being oxidized over the surface of the metallic sodium and an apparatus therefor. The metallic sodium is fed into a cavity of the hollow valve in which a valve stem has a smaller diameter. A workpiece, a semi-finished product for a hollow poppet valve, is disposed at a working position where an opening is directed upward. A cavity of the workpiece is open at a free end of the valve stem. A nozzle is inserted into the opening. An inert gas is jetted from the nozzle and is fed into the cavity. Then, the nozzle is moved up, and a holder that holds the rod-like metallic sodium 10 is disposed between the workpiece and the nozzle. While the inert gas is jetted from the nozzle, the metallic sodium is pressed into the cavity of the workpiece.

Abstract: Oxide film formed on a spring-retaining flange by heat treatment gets unlikely to peel off, thereby improving wear resistance of a contact surface of the spring-retaining flange with a valve spring. The oxide film 15 of the part of the spring-retaining flange 3 with the valve spring 7 is at least partially removed to make thickness of the oxide film to 0.00 to 0.02 ?m.

Abstract: Oxide film formed on a spring-retaining flange by heat treatment gets unlikely to peel off, thereby improving wear resistance of a contact surface of the spring-retaining flange with a valve spring. The oxide film 15 of the part of the spring-retaining flange 3 with the valve spring 7 is at least partially removed to make thickness of the oxide film to 0.00 to 0.02 ?m.

Abstract: A rod material made of Ti alloy has a larger diameter portion at the end, which is joined with the end of material made of Ti—Al intermetallic compound, by friction welding, to form a poppet valve for an internal combustion engine. Instead of providing such larger diameter portion, the end of the material made of Ti—Al intermetallic compound may be heated to facilitate joining.

Abstract: A Ti alloy poppet valve consists of a valve stem and a valve head, and is employed as intake or exhaust valve in an internal combustion engine of an automobile. O2 is put into the valve in a furnace at very slight amount and heated to introduce oxygen atoms into titanium of the valve to form a Ti—O interstitial solid solution without making titanium oxides. The valve is strengthened to increase hardness and wear resistance.

Abstract: A tappet is used in a valve-operating mechanism of an internal combustion engine. The tappet has a top wall and the upper surface of the top wall is engaged with a cam. The lower surface is engaged on a poppet valve which moves up and down. A downward projection which has a recess for storing lubricating oil is formed in the middle of the lower surface of the top wall of the tappet, thereby lubricating interfaces with the cam or valve to improve frictional or wear resistance.

Abstract: Ti alloy is embedded in a powder such as graphite and heated with the powder in an oxygen atmosphere. Oxygen atoms are diffused into the Ti alloy to form an oxygen diffusion layer of Ti—O solid solution, thereby increasing wear resistance of the valve. A poppet valve in an internal combustion engine may be made of such Ti alloy.

Abstract: A multi-valve engine comprises a plurality of intake and exhaust valves on a cylinder. Depending on use, one of the valves is made of higher heat-resistant material, and another is made of lower heat-resistant material, thereby decreasing cost and improving durability and reliability.

Abstract: Ti alloy is heated in an atmosphere of CO2 in a heating furnace. O and C atoms are introduced into the Ti alloy to harden it without forming Ti oxide, thereby increasing hardness by Ti—O and Ti—C solid solutions thus formed.

Abstract: A tappet is used in a valve-operating mechanism of an internal combustion engine. The tappet has a top wall and the upper surface of the top wall is engaged with a cam. The lower surface is engaged on a poppet valve which moves up and down. A downward projection which has a recess for storing lubricating oil is formed in the middle of the lower surface of the top wall of the tappet, thereby lubricating interfaces with the cam or valve to improve frictional or wear resistance.

Abstract: A Ti alloy poppet valve consists of a valve stem and a valve head, and is employed as intake or exhaust valve in an internal combustion engine of an automobile. O2 is put into the valve in a furnace at very slight amount and heated to introduce oxygen atoms into titanium of the valve to form a Ti—O interstitial solid solution without making titanium oxides. The valve is strengthened to increase hardness and wear resistance.

Abstract: A rod material made of Ti alloy has a larger diameter portion at the end, which is joined with the end of material made of Ti—Al intermetallic compound, by friction welding, to form a poppet valve for an internal combustion engine. Instead of providing such larger diameter portion, the end of the material made of Ti—Al intermetallic compound may be heated to facilitate joining.

Abstract: A poppet valve moves up and down in a valve operating mechanism in an internal combustion engine. A cylindrical fixed electrode is fixed to a support plate on a cylinder head, and a cylindrical moving electrode is mounted to the lower surface of a valve spring retainer which is mounted to the poppet valve via a cotter. The fixed electrode is connected to a circuit which comprises a variable condenser and a resistance. The valve moves up and down during firing operation of the engine. Thus, variation in electrostatic capacity is detected by the two electrodes, transmitted to a circuit via a lead mounted to the fixed electrode, and converted to a voltage by the circuit, thereby detecting valve position exactly.

Abstract: To operate a poppet valve in an internal combustion engine, a valve operating mechanism comprises a valve spring retainer which has a taper bore, a pair of cotters which is inserted in the bore to support the poppet valve, and a valve spring between the valve spring retainer and a cylinder head. There is provided means for preventing the cotters from falling out the bore.

Abstract: A bar material is made of an (&agr;+&bgr;) or a near &agr; Ti alloy which comprises a regular &agr; structure, and the end thereof is heated at a temperature above its &bgr; transformation point by an electric forging device to form an enlarged portion. The enlarged portion is immediately formed by hot forging to make a valve head of a poppet valve which is employed in an internal combustion engine. The valve head comprises an acicular &agr; structure which provides higher fatigue and tensile strengths.

Abstract: A valve spring retainer is mounted to the upper end of a poppet valve via a pair of cotters in an internal combustion engine of an automobile. The valve spring retainer has an intermediate portion and an outer flange which is engaged with the upper end of a valve spring. The lower surface has a gap between the outer flange and the intermediate portion to decrease wear which is caused by engagement with the valve spring. There is also provided a valve operating mechanism which has a valve spring retainer which has a projection on the lower surface so as to prevent wear.

Abstract: To operate a poppet valve in an internal combustion engine, a valve operating mechanism comprises a valve spring retainer which has a taper bore, a pair of cotters which is inserted in the bore to support the poppet valve, and a valve spring between the valve spring retainer and a cylinder head. There is provided means for preventing the cotters from falling out the bore.

Abstract: A poppet valve moves up and down in a valve operating mechanism in an internal combustion engine. A cylindrical fixed electrode is fixed to a support plate on a cylinder head, and a cylindrical moving electrode is mounted to the lower surface of a valve spring retainer which is mounted to the poppet valve via a cotter. The fixed electrode is connected to a circuit which comprises a variable condenser and a resistance. The valve moves up and down during firing operation of the engine. Thus, variation in electrostatic capacity is detected by the two electrodes, transmitted to a circuit via a lead mounted to the fixed electrode, and converted to a voltage by the circuit, thereby detecting valve position exactly.