JP2009228823A - Connection structure of piston and connecting rod - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight connection structure of a piston and a connecting rod, having durability. <P>SOLUTION: This connection structure 1 of the piston sand the connecting rod is formed by connecting the piston 2 and the connecting rod 4 via a piston pin 3, by integrally forming a single boss 21 for journaling the piston pin 3 in the lower center of the piston 2, and is constituted so that the piston pin 3 includes a hollow part 31 and a cutout part 32 formed in the axial direction of the piston pin 3 from one end of the piston pin 3, and a small end part 41 of the connecting rod 4 storably formed in the hollow part 31 is installed in the hollow part 31 via the cutout part 32. This connection structure 1 of the piston and the connection rod is also constituted by installing a piece 5 for filling the cutout part 3 after installing the small end part 41 in the hollow part 31. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a connecting structure of a piston and a connecting rod.

  FIG. 5 is a diagram schematically showing an example of a conventional general piston. Conventionally, as shown in FIG. 5, the piston is generally provided with two pin bosses for pivotally supporting the piston pin. On the other hand, a piston (hereinafter referred to as a single boss piston) provided with two pin bosses integrally at the lower center of the piston is also known. The single boss piston has, for example, the following advantages compared with a general piston as shown in FIG.

That is, in a general piston, a pin boss end surface as shown in the figure is formed in the upper part of the piston pin hole inside the pin boss, and this pin boss end surface becomes an edge, so that when a combustion load is repeatedly received, When a crack sometimes occurs, such a pin boss end face does not exist above the pin hole in the single boss piston, and therefore the occurrence of such a crack can be prevented.
In addition, the length of the piston pin is determined by the connecting rod width and the contact area with the piston, but in a single boss piston, it is not necessary to consider the connecting rod width when determining the length of the piston pin. Accordingly, the length of the pin can be shortened, so that the weight of the piston can be reduced as an assembly including the piston pin.

  With regard to such a single boss piston, for example, Patent Document 1 discloses a structure in which the single boss is an assembly structure separate from the piston. Patent Document 2 discloses a structure in which a notch for inserting a connecting rod is provided in the lower part of a single boss. In addition, for example, Patent Document 3 discloses a structure in which a coupling structure between a piston and a connecting rod is a spherical coupling structure. This spherical connection structure is also considered to be related to the present invention in that it is considered to be a kind of single boss piston, but it is fundamentally different from the present invention in that it is a connection structure that does not employ pin coupling. It is considered that the technology is different.

JP 61-002973 A JP 2000-081134 A JP 2006-274861 A

For example, in the separate assembly structure disclosed in Patent Document 1, it is considered that when the inertial force acts on the piston, the strength of the single boss coupling portion is insufficient and may be disassembled. There is concern that there is a problem in terms of durability.
Further, in the case of the structure disclosed in Patent Document 2, for example, it is considered that the strength of the single boss is insufficient at the notched portion, and as a result, there is a possibility of damage. I am concerned that there is a problem.

  Then, this invention is made | formed in view of said subject, and it aims at providing the connection structure of a durable lightweight piston and connecting rod.

  In order to solve the above-mentioned problems, the present invention provides a piston boss connecting a piston and a connecting rod, wherein a pin boss that pivotally supports a piston pin is integrally formed at the lower center of the piston and the piston and the connecting rod are connected via the piston pin. The piston pin has a hollow portion and a notch formed along the axial direction of the piston pin from one end of the piston pin, and can be accommodated in the hollow through the notch The small end portion of the connecting rod formed in the above is assembled to the hollow portion.

  Moreover, the structure which assembled | attached the piece which fills the said notch part after the said small end part was assembled | attached to the said hollow part may be sufficient.

  In the present invention, the first length corresponding to the axial direction of the piston pin in the cross-sectional shape in the vicinity of the small end portion of the rod portion of the connecting rod corresponds to the second direction substantially perpendicular to the axial direction. The configuration may be a rectangular shape longer than the length, and the width of the notch may be set in accordance with the second length.

  According to the present invention, the connection structure between the piston and the connecting rod can be made durable and lightweight.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an exploded perspective view showing a piston / connecting rod connecting structure (hereinafter simply referred to as the connecting structure) 1 according to this embodiment. Further, in FIG. 2, in order to facilitate understanding of the shape, the piston 2, the piston pin 3, and the connecting rod 4 of the coupling structure 1 are respectively shown in front view, side view, bottom view, and perspective view. Further, in FIG. 3, in order to facilitate understanding of the shape, the coupling structure 1 is shown in one pin hole front view, the other pin hole front view, bottom view, and perspective view, as well as a pin shaft cross-sectional view and a thrust shaft cross-sectional view. The pin shaft cross section and the thrust shaft cross section are respectively shown. This connection structure 1 includes a piston 2, a piston pin 3, a piece 4, and a connecting rod 5.

  The piston 2 is a so-called single boss piston, and includes a pin boss (hereinafter referred to as a single boss) 21 formed integrally with the lower center of the piston 2. Thus, by forming the single boss 21 at the lower center of the piston 2 instead of being provided as a separate body, the strength of the piston 2 can be increased, and thus the durability can be improved. Side walls 22 are formed on both sides of each end of the single boss 21. The sidewall 22 is connected to a skirt 23 formed in a partial cylindrical shape.

  The single boss 21 includes a pin hole 211 and an opening 212. The pin hole 211 is formed so that its cross-sectional shape is substantially a circle. The opening 212 is formed at the center lower portion of the single boss 21 and opens the pin hole 211 downward. In the axial direction of the pin hole 211, the opening 212 has an opening width that is set to the same size as the width (first length) of the connecting rod 4, and in a direction substantially orthogonal thereto. The opening width is set to a size capable of avoiding interference with the connecting rod 4.

The piston pin 3 is a hollow cylinder provided with a hollow portion 31 formed along the axial direction of the piston pin 3 (or directions corresponding to the axial direction of the pin hole 211. These directions are hereinafter simply referred to as pin axial directions). The hollow portion 31 penetrates at both ends of the piston pin 3. The outer diameter of the piston pin 3 is set to the same size as the pin hole 211, and the piston pin 3 is slidably rotated with respect to the pin hole 211 in a state where it is assembled to the pin hole 211.
Moreover, the piston pin 3 is provided with the notch part 32 formed along the pin axial direction from the end. The width of the notch 32 is set to a size equivalent to the thickness (second length) of the portion near the small end 41 of the rod portion 42 of the connecting rod 4. The length of the piston pin 3 is set to a length equivalent to the length of the single boss 21 in the pin axis direction. In addition, since it is thought that the piston pin 3 is a product made from casting and can ensure high intensity | strength, even if it provides the notch part 32, the problem of durability will not arise especially.

The connecting rod 4 includes a small end portion 41 that can be accommodated in the hollow portion 31. The small end portion 41 is formed in accordance with the shape of the hollow portion 31. Specifically, the small end portion 41 is formed in a cylindrical shape having a central axis in a direction corresponding to the pin axis direction, and the outer diameter of the small end portion 41 is the inner diameter of the piston pin 3 (outside of the hollow portion 31). (Diameter) is set to the same size. The connecting rod 4 is assembled into the piston pin 3 through the notch 32 (specifically, by passing the rod part 42 near the small end 41 through the notch 32).
The rod portion 42 in the vicinity of the small end portion 41 is formed so that the cross-sectional shape thereof is a rectangular shape, and the width (first length) corresponding to the pin axis direction is substantially orthogonal to this. It is set so as to be larger than the thickness (second length) corresponding to the direction in which it is performed.

  The cross-sectional shape of the rod portion 42 in the vicinity of the small end portion 41 is based on the viewpoint that the width of the notch 32 (a dimension shown in FIG. 2) is made as small as possible from the viewpoint of durability. As a result of setting the cross-sectional area to the minimum necessary cross-sectional area for securing (b dimension x c dimension shown in FIG. 2), the width corresponding to the pin axis direction (c dimension shown in FIG. 2) is substantially orthogonal to this. The thickness is larger than the thickness corresponding to the direction (b dimension shown in FIG. 2). That is, this cross-sectional shape is advantageous in terms of durability as well as the shape (specifically, width) of the notch 32.

The piece 5 is a member formed in a partial cylindrical shape. FIG. 4 shows a state in which the piece 5 is fitted in the piston pin 3 alone for easy understanding of the shape. The width of the piece 5 is set to be equal to the width of the notch 32, and the arc is formed so as to follow the inner and outer diameters of the piston pin 3 in a state of being fitted into the notch 32. . The length corresponding to the pin axis direction of the piece 5 is set to a length equivalent to the length from the end of the single boss 2 to the opening 212 in the pin axis direction.
The piece 5 is attached to the notch 32 of the piston pin 3 assembled in the pin hole 211 (the notch 32 after the small end 41 is assembled to the hollow part 31) while the small end 41 is assembled to the hollow part 31. On the other hand, it is assembled so as to fill the notch 32, thereby eliminating the notch, preventing local contact between the pin hole 211 and the notch 32, and improving the durability.

  In this connection structure 1, first, the small end 41 of the connecting rod 4 is inserted into the opening 212 of the single boss 21, and then the piston pin 3 is inserted into the pin hole 211 from the side where the notch 32 is formed, At the same time, this is realized by assembling the small end portion 41 into the hollow portion 31 through the notch 32 and finally fitting the piece 5 into the notch 32 from the side opposite to the side where the piston pin 3 is inserted.

Since the connecting structure 1 having the above-described structure does not have a notch for inserting the connecting rod 5 in the lower part of the single boss 21, the durability of the lower part of the single boss 21 can be improved. By forming 21 on the piston 2, durability as a single boss piston can be improved.
Moreover, this connection structure 1 can improve durability by the cross-sectional shape of the rod part 42 near the small end part 41, and the shape of the notch part 32, and also the pin hole 211 and the notch part 32 with the piece 5 In addition to preventing local contact, durability can be improved.
At the same time, the connection structure 1 can improve the durability around the pin hole 211 as compared with the above-described general piston, and the width of the connecting rod 4 is specially determined in determining the length of the piston pin 3. Since it is not necessary to consider, the length of the piston pin 3 can be shortened, and thus the weight of the piston as an assembly including the piston pin 3 can be reduced.

  The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, the piston pin 3 is preferably a hollow cylindrical shape from the viewpoint of manufacturability and the like, but the cross-sectional shape of the hollow portion of the piston pin 3 does not have to be substantially circular, The shape of the small end portion 41 of the connecting rod 4 incorporated in may be appropriately modified. The hollow portion preferably penetrates at both ends of the piston pin 3 from the viewpoint of manufacturability and weight reduction. For example, the hollow portion penetrates at the end opposite to the side where the notch 32 is formed. Even a shape that is not included is included in the hollow portion described in the present invention.

It is a perspective view which decomposes | disassembles and shows this connection structure. It is a figure which shows piston 2, piston pin 3, and connecting rod 4 in this connection structure 1 with a front view, a side view, a bottom view, and a perspective view, respectively. The coupling structure 1 is shown in one pin hole front view, the other pin hole front view, bottom view, and perspective view, as well as in a pin shaft cross-sectional view, thrust shaft cross-sectional view, pin shaft cross-sectional view, and thrust shaft cross-sectional view, respectively. FIG. FIG. 3 is a perspective view showing a state where a piece 5 is fitted into a piston pin 3. It is a perspective view which shows a general piston.

Explanation of symbols

1 connection structure 2 piston 21 single boss 211 pin hole 212 opening 22 sidewall 23 skirt 3 piston pin 31 hollow 32 notch 4 connecting rod 41 small end 42 rod 5 piece

Claims (3)

A pin boss that pivotally supports the piston pin is integrally formed in the lower center of the piston, and the piston and the connecting rod are connected by connecting the piston and the connecting rod via the piston pin,
The piston pin includes a hollow portion and a notch portion formed along the axial direction of the piston pin from one end of the piston pin, and is formed so as to be accommodated in the hollow portion through the notch portion. A connecting structure of a piston and a connecting rod, wherein a small end portion of the connecting rod is assembled to the hollow portion. The piston and connecting rod connection structure according to claim 1,
A piston / connecting rod connecting structure, wherein a piece for filling the notch portion is further assembled after the small end portion is assembled to the hollow portion. A connection structure of the piston and connecting rod according to claim 1 or 2,
The first length corresponding to the axial direction of the piston pin in the cross-sectional shape near the small end portion of the rod portion of the connecting rod is longer than the second length corresponding to the direction substantially orthogonal to the axial direction. A piston and connecting rod connection structure characterized by having a long rectangular shape and the width of the notch being set in accordance with the second length.

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