JP2008240536A - Lightening structure of poppet valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide lightening structure of a poppet valve for easily performing boring work when boring a hole in a stem in a hollow shape, by reducing weight of a valve element part, without reducing rigidity of a joining part of the stem and a valve element. <P>SOLUTION: This lightening structure is constituted by integrally arranging the valve element of arranging a conical valve surface seated on a valve seat and the tubular stem extending in the apex direction of the valve surface from a central part of its valve element. A lightening hole communicating with the stem is arranged in a central part of a combustion chamber surface of the valve element. Its lightening hole is constituted of a relatively large diameter first hole opening on the combustion chamber side and a relatively small diameter second hole extending inside the stem from a central part of its first hole. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light weight poppet valve suitable for a high-performance automobile engine mainly including a motorcycle.

  Generally, a poppet valve used as an intake / exhaust valve of an engine is metallurgically processed by hot forging from an umbrella-shaped valve body having a conical valve surface to a round bar-shaped stem guided by a valve guide. It is manufactured integrally. Therefore, not only the valve body but also the stem is solid, and since the inertia weight is large, improvement is demanded from the viewpoint of the economical efficiency of the material and the reduction of fuel consumption.

  On the other hand, when the poppet valve is used as an exhaust valve, a stem having a hollow stem and enclosing sodium inside is commonly used to prevent overheating. Such hollowing of the stem greatly contributes to weight reduction as a result, so that use as a means for weight reduction has been studied (see Patent Document 1).

  However, conventionally, the weight reduction has been limited to the stem portion, not the umbrella-shaped valve body portion, and although it has been studied, it has not been put into practical use. As an example of reducing the weight of the valve body, the main one is that the weight of the valve body is accidentally reduced in the process of hollowing the stem (see Patent Document 1). Moreover, although it is a rare example, the thing of the shape which leaves several ribs around a stem and leaves a rib is proposed (refer patent document 2).

However, the former is made by a cold forging method that requires multiple steps, and is not suitable for forming by conventional forging and is expensive. Moreover, even if the latter can be forged, the rigidity of the joint portion between the stem and the valve plate portion facing the combustion chamber of the valve body cannot be increased, and there is a problem that reinforcement is not easy.
JP 2003-65013 A JP 2003-343219 A

  The problem to be solved is to reduce the weight of the valve body without lowering the rigidity of the joint between the stem and the valve body, and to easily drill the stem when drilling the stem hollow. The object is to obtain a fillet structure of the poppet valve.

  The present invention includes a valve body provided with a conical valve surface that is seated on a valve seat, and a stem that extends from the axial core portion of the valve body toward the apex direction of the valve surface, and the valve body is formed as an outer edge. An annular valve portion having a valve surface formed therein, a root portion formed of a conical cylindrical body disposed in the axial center portion and expanding in the direction of the combustion chamber, and a circle connected to the valve portion between the valve portion and the root portion The plate-shaped valve lid is connected to a plurality of reinforcing ribs whose height increases in the axial direction, the small diameter side of the root is connected to the stem, and the large diameter side is closed by a disk-shaped first lid. The most important feature is that

  In the poppet valve according to the present invention, the valve body is thinned by several fan-shaped concave portions arranged around the stem, and the stem extended line is also thinned by the large-diameter first hole. Therefore, since the valve body has no meat on the extension of the stem, the weight can be reduced.

  In addition, since the outer surface of the root portion formed of the cylindrical body expands from the stem toward the combustion chamber, the root portion connected to the stem and the disc-shaped valve lid portion connected to the valve portion are connected with high rigidity, and the thin wall Thus, there is an advantage that there is no decrease in strength even if the weight is reduced. In addition, the root portion and the valve lid portion are sandwiched between upper and lower molds during forging, so that the structure becomes dense and the mechanical strength can be further improved.

  Since the large-diameter first hole is provided on the extension line of the stem, a hole for forming a lightening hole or a later machined pilot hole is formed in the stem portion by a die during forging. It is easy and does not become difficult to manufacture due to weight reduction.

  Further, when a hollow valve is formed by drilling in the stem, each of the openings of the first hole and the second hole is sealed with a steel ball, a disk, etc., so that fluid heat transfer such as sodium is in the second hole. Even when the member is enclosed, the second lid (steel ball) enclosing the heat transfer member is covered with the first lid and is not exposed to the combustion chamber, so there is no problem that causes premature ignition or knocking. There are advantages such as.

  Embodiments according to the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 10 denotes an engine exhaust valve. The exhaust valve 10 has a valve body 15 provided with a conical valve surface 12 seated on a valve seat of an engine (not shown), and a tubular shape extending from the axial core portion of the valve body 15 toward the apex direction of the valve surface 12. It consists of a stem 20.

  The valve body 15 has an umbrella-shaped contour similar to that of a conventional poppet valve. The valve body 15 is located on the stem side and is substantially fan-shaped around the stem 20. The difference is that a first hole 25a having a relatively large diameter is formed in the center portion. That is, the valve body 15 includes an annular valve portion 16 having the valve surface 12 formed on the outer edge, a conical root portion 21 having a large diameter on the combustion chamber side, and a valve lid portion 18 that closes the combustion chamber side of the valve portion 16. The structure is connected to the reinforcing rib 19.

  The root portion 21 is formed in a conical shape whose inner and outer diameters decrease from the combustion chamber side toward the stem side, and the large diameter side is formed at the periphery of the opening portion of the first hole 25a formed in the center of the valve lid portion 18. The small diameter side is connected with the stem 20. A bottom portion 23 is provided on the small diameter side of the root portion 21, and a second hole 25 b having a relatively small diameter and extending from the center portion of the bottom portion 23 toward the straight portion 22 of the stem 20 is provided.

  In the example of FIG. 1, the second hole 25b having a relatively small diameter is a hole for enclosing sodium inside, and is drilled by a gun drill to the vicinity of the cotter groove 24. In the example of FIG. It is used as a simple hole for drilling, or as a pilot hole drilled by the gun drill.

  Thus, the valve body 15 is formed into a thin plate shape except for the annular valve portion 16 by the six lightening recesses 14 and the large-diameter first holes 25a, and is lightweight. On the other hand, the rigidity of the joint between the valve portion 16 and the stem 20 can be obtained by the action of the root portion 21, and the weight can be reduced without impairing the mechanical strength because the dense structure is formed by forging. .

  The stem 20 is integrally forged and connected to a cylindrical root portion 21 having a gradient that forms a part of the valve body 15, and forms a straight portion 22 supported by a valve guide (not shown). A well-known cotter groove 24 is provided in the vicinity of the end portion of the stem 20 to urge the stem 20 in the valve closing direction by the elasticity of a return spring (not shown). A hollow hole 25 is formed concentrically with the axis of the stem 20 from the direction of the valve body 15.

  Reference numeral 26 denotes a steel ball serving as a second lid press-fitted into the opening of the second hole 25b, and 27 denotes a disk-shaped first lid welded so as to cover the opening of the first hole 25a. Reference numeral 23a denotes a trace in which three spots are equally spot welded to the peripheral edge of the second hole 25b in order to prevent the steel ball 26 from dropping off. Note that the steel ball may be a sealed lid even if it is a taper plug or flat plate welding.

  Although the exhaust valve 10 according to the above embodiment is formed by drilling a hole 25 to be drilled into the straight portion 22 of the stem 20 from the valve body 15 side, By utilizing the fact that the portion is located in the large diameter portion of the valve body 15, the lightening hole 25 is divided into a large diameter first hole 25a and a small diameter second hole 25b. Since the length is shortened, the molding becomes easy, and it becomes unnecessary to perforate the straight portion 22 over several steps, or the molding can be performed without increasing the thickness of the straight portion 22.

It is a longitudinal cross-sectional view of the engine exhaust valve which concerns on this invention. It is II-II sectional drawing in FIG. It is a longitudinal cross-sectional view equivalent to FIG. 1 which shows another Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Exhaust valve 12 Valve surface 14 Fan-shaped recessed part 15 Valve body 16 Valve part 18 Valve cover part 19 Reinforcement rib 20 Stem 21 Root part 22 Straight part 22a Trace of caulking process 23 Bottom 23a Trace 24 Cotter groove 25 Meat hole 25a 1st hole 25b Second hole 26 Steel ball (second lid)
27 Disc (first lid)

Claims (3)

  A valve body provided with a conical valve surface to be seated on the valve seat; and a stem extending from an axial core portion of the valve body toward a vertex direction of the valve surface, and the valve surface with the valve body as an outer edge. An annular valve portion formed, a root portion made of a conical cylindrical body disposed in the axial center portion and expanding in the direction of the combustion chamber, and a valve lid portion having a disk shape between the valve portion and the root portion The meat of a poppet valve which is connected by a plurality of reinforcing ribs whose height increases in the axial direction, the small diameter side of the root is connected to the stem, and the large diameter side is closed by a disc-shaped first lid. Unplug structure.   2. The poppet valve lightening structure according to claim 1, wherein an annular bottom portion is provided at the small diameter end of the root portion, and a lightening hole is drilled as necessary.   In Claim 1, the small-diameter end of the root portion is provided with an annular bottom portion, a lightening hole is provided from the center of the bottom portion to the stem, and sodium contained therein is closed by a second lid made of a steel ball. The poppet valve's meat removal structure.

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