JPS59155516A - Pushrod of internal-combustion engine - Google Patents

Abstract

PURPOSE:To obtain a pushrod, which is light in weight and excellent in strength and suitable for high speed engine, by a structure wherein the pushrod is molded out of resin material so the the sectional moment of inertia and/or sectional area at the intermediate portion in the longitudinal direction is made larger than that at both the end parts of the pushrod. CONSTITUTION:A pushrod 1 is molded out of resin material in such a form as the diameter becoming gradually larger from both the end parts 1b toward the intermediate part 1a so that the sectional area at the intermediate part 1a in the longitudinal direction of the pushrod 1 becomes larger than that at both end parts 1b. For example, let A denote the sectional area at both the end parts 1b, then the sectional area at the intermediate part 1a is made 2A. Consequently, the stress at the intermediate part 1a becomes in inverse ratio to the square of the sectional area or 1/4, resulting in obtaining a pushrod having the increased strength against buckling load.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bushing rod for an internal combustion engine molded from a resin material.

Traditionally, steel has been generally used as bushing rods for internal combustion engines, and although steel bushing rods have sufficient strength, they have the disadvantage of being heavy.
As a result, the inertial force increases at high speeds, resulting in an increase in so-called jumps and bounces, making it unsuitable for high-speed operation. Therefore, in order to solve this problem, for example, as seen in Utility Model Application Publication No. 57-15908, the bushing rod body is molded from a resin material such as carbon fiber reinforced resin, and the weight is reduced and the speed of operation is increased. It is considered possible to do so. However, as shown in Table I below, such resin materials have the disadvantage of being weaker in strength and rigidity than steel materials. That is, the bushing rod has both ends in free contact with the tappet and valve arm;
°Since the load W that operates the valve mechanism is received as compression,''
A general long and thin bushing rod must withstand deformation due to buckling. The buckling strength w due to both ends is:
As the basis of material mechanics, ζEuler's formula (which is expressed by the following equation).

For bush rods with the same cross-sectional shape,
From this equation, the buckling strength is controlled by the elastic modulus of the material, so the strength of resin-based materials is significantly weaker.

Table 1 The present invention was made with the aim of eliminating the drawbacks of such resin bushing rods, and to provide a bushing rod with increased rigidity against compressive loads and increased buckling strength. In the invention, the bushing rod body is molded from a resin material including resin reinforced with glass fiber or the like, and the cross-sectional moment of inertia and/or cross-sectional area of the middle part in the longitudinal direction of the bushing rod body is larger than that of both ends of the bushing rod body. It is characterized by this.

Hereinafter, the structure of the present invention will be explained in more detail based on the illustrated embodiment.As shown in FIG.
1) is molded from a resin material, and the bushing rod (11) is molded at both ends so that the cross-sectional area of the longitudinally intermediate portion (1a) of the bushing rod 11 is larger than the cross-sectional area of both ends (1b) (1b') of the bushing rod 10. It is formed so that the diameter becomes larger from the part (1b) toward the middle part (1a).Such a difference in cross-sectional area is caused by, for example,
If the cross-sectional area of is A, then the cross-sectional area of the middle part (la) is 2
Let's call it A. By doing this, 1. Middle part (
The stress of la) is ``reflected by the square of the cross-sectional area'', and then A
σ, and a bushing rod (1) with increased strength against buckling load can be obtained.

Also, when the bushing rod (1), which is freely supported at both ends, receives a pressure load W, the bushing rod (1)
Since the position of

M=wy This moment M becomes a force that buckles the bushing rod (1), but its value is at the center of the total length l, that is, when the deformation of the push port/nod (1) draws a sine curve, that is, X-β /2
y becomes the maximum value.

Therefore, when considering the cross-sectional shape of the bushing rod (1) to obtain the buckling strength using Euler's equation, the cross-sectional moment of inertia I that defines the cross-sectional strength of the bushing rod (1) is the center of β -β/2 is sufficient to satisfy the formula, and as shown in Fig. 8, the moment of inertia I, that is, the cross-sectional dimension, increases in proportion to the height y of the sinusoidal curve as it approaches both support points from the center. Can be made smaller.

In addition, the maximum cross-sectional moment of inertia I of the shape in FIG.
is expressed by the following formula.

The cross-sectional area, ie, shape, and shape may be set so that the simple compressive stress W/A is equal to or less than the yield point of the material used in the following equation in the portions near the support points at both ends where the bending moment can be ignored.

Wc -σS Life A σS: Yield point of material Wc: Compressive load The material of the resin material may be, for example, carbon fiber reinforced resin, glass fiber reinforced resin, or other engineering resin. The most common shape produced by injection molding is the bushing rod (1
) The shape of the cross-sectional area can also be considered to be a solid circle using the ing method. Figure 2 shows the shape obtained by using the filament winding method in this way. ) has a hollow circular cross section.

Figures 3 and 4 show other shapes of the Pu Noshro Nod (1), and Figure 3 shows both ends (1b) (1b) of the Pu Noshro Sod (1). The middle part (l
Part a) has an H-shaped cross-section, and FIG. 4 shows a cross-sectional cross-section of the middle part except for both ends. The maximum cross-sectional inertia I of these shapes in FIGS. 3 and 4 is as shown in FIG. 3, and the weight can be reduced compared to the solid shape in FIG. 1. FIG. 5 shows the shape of FIG. 4 further modified to have a rounded cross-sectional shape.

In addition, in any of the cases shown in FIGS. 3 to 5, both ends (lb) of the bushing rod fl) (lb)
has a solid circular cross section. Moreover, each of these embodiments can be molded by injection molding.

Figure 6 shows an embodiment in which a resin push rod (1) is provided with caps (2) at both ends to ensure wear resistance of the sliding portions at both ends. Figure (a) shows a bushing rod (1) with a concave part (3) on the end face and a protrusion (4) on the base (2), and the two are fitted together, and figure (b) shows a bushing rod on the contrary. (1) A convex part (4) on the end and a concave part (3) on the base (2) and fitted together, the same figure (C
) is a bushing rod (11 with the end slightly tapered and fitted into the recess (5) of the base (2), as shown in the same figure (d).
), in the same struggle as in FIG. 6(b), the outer periphery of the convex part (4) of the bushing rod (11
) annular grooves (6a) '(6
b) with such annular grooves (6a) (6b)
; is shown fitted with an identical retaining ring (7). Incidentally, such a cap (2) can be integrally fixed at the same time when the bushing rod (J, l) is injection molded.

As explained above, according to the present invention, in a bushing rod molded from a resin material, the cross-sectional moment of inertia and/or cross-sectional area of the middle part of the bushing rod is made larger than the cross-sectional area of both ends, so that the bushing rod is lightweight. Moreover, it is possible to obtain a bushing rod that has excellent strength and is suitable for high-speed engines.

[Brief explanation of the drawing]

1 to 5 each show the structure of a bushing rod according to an embodiment of the present invention. In each figure, (a) is a front view, (b) is a cross section of the intermediate part, and ( C) shows the cross section of both ends, FIGS. 6(a) to (d) are longitudinal sectional views of the end of the bushing rod showing the various mounting structures of the base, respectively, and FIG. An explanatory diagram showing the state, FIG. 8 is a graph 3. showing the relationship between the bushing rod length and the cross-sectional moment of inertia. It is. (1 Taupe Soshurono, Do, (la) - middle part (lb
) One end, (2)--cap. Patent Applicant Yanmar Diesel Co., Ltd., Patent Attorney Hisayuki Tarumoto Figure 6 (a) Figure 7 Figure 8

Claims (1)

[Claims] A bushing rod for an internal combustion engine, characterized in that the bushing rod body is molded from a resin material, and the cross-sectional moment of inertia and/or cross-sectional area of the longitudinally intermediate portion thereof are larger than those of both ends of the bushing rod body.