JPS6285154A - Piston - Google Patents

Abstract

PURPOSE:To collect the lubricant and to cool the head of a piston effectively, by forming a recessed portion to reach the rear side of a ring groove furnished at the outside of the head, at the lower side of the head against a cutting arranged at the pin hubs and the neighboring positions of the skirt. CONSTITUTION:The piston 1 for an engine consists of a head 2, a pair of pin hubs 3 arranged on the same axis at both sides of the piston axis Y projected unitary at the lower side of the head 2, and a skirt 4 connected unitary to the lower periphery of the head 2. In the skirt 4, a cutting 9 is formed at the neighboring positions of each pin hub 3 in the direction to the periphery. In such a composition, at the lower side of a ring belt 7 against the cutting 9, a recessed portion 12 is furnished, which is formed at least to reach the rear side of the third ring groove 83 which is engraved at the outside of the ring belt 7. Therefore, the lubricant collected to the cutting 9 is penetrated to the recession 12 to cool the head 2 effectively.

Description

Detailed Description of the Invention A0 Object of the Invention (1) Industrial Application Field The present invention relates to a piston mainly used in an engine, particularly a head portion having a ring groove on the outer periphery, and a piston provided integrally on the lower surface of the head. The present invention relates to a piston comprising a pair of pin boss portions arranged coaxially across the piston axis, and a skirt portion integrally continuous with the lower peripheral edge of the head portion.

(2) Prior art Conventionally, in order to reduce the weight and sliding area of this type of piston, it has been known to provide a notch in the skirt portion adjacent to the pin boss portion (for example, in practice Kaisho 6
0-26254).

(3) Problems to be Solved by the Invention Since the cutout exposes the lower surface of the head, the lubricating oil that is scraped into the cutout from the inner wall of the engine cylinder by the oil ring attached to the ring groove of the head is removed.
It also contributes to cooling the head by sprinkling it on the exposed underside of the head.

However, since the head portion is formed to be relatively thick in order to have a large heat capacity, satisfactory cooling cannot be expected just by sprinkling lubricating oil onto the lower surface of the head portion exposed within the notch.

Therefore, an object of the present invention is to provide the piston in which the head portion can be effectively cooled by the lubricating oil collected in the notch.

B0 Structure of the Invention (1) Means for Solving the Problems In order to achieve the second object, the present invention provides four parts reaching the back side of the groove on the lower surface of the head facing the notch. It is characterized by:

(2) Operation The lubricating oil collected from the inner wall of the cylinder of the engine into the cutout of the skirt part enters the recess opening on the lower surface of the head, and the head part can be effectively cooled from inside.

The recess also contributes to reducing the weight of the piston.

Furthermore, since the four parts open into the notches, they can be formed by casting together with the notches.

(3) Example Hereinafter, an example of the present invention will be described with reference to the drawings. In FIG. 1, an engine piston 1 is made of aluminum alloy, and is integrated with a head portion 2 and a lower surface of this radius portion 2. It consists of a pair of pin boss parts 3゜3 arranged in parallel with each other across the piston axis Y, and a skirt part 4 extending from the lower periphery of the head part 2 to the body. 3 is provided with pin holes 5, 5 for supporting a piston pin (not shown).

The skirt portion 4 is tapered so that its outer diameter slightly increases downward, and when the engine is at high temperature, it assumes a cylindrical shape due to the temperature difference between the upper and lower ends of the skirt 4. There is.

Further, as shown in FIG. 2, the skirt portion 4 is formed so that its cross section is an ellipse with the minor axis a directed in the axial direction of the pin boss 3.3 (i.e., a<b), so that Occasionally, the presence of relatively thick pin bosses 3.3 also results in a perfectly circular cross-sectional shape.

In FIG. 5, the head portion 2 includes a top wall 6 and a top wall 6.
It consists of a cylindrical ring belt 7 that is thicker than the skirt part 4 and is integrally continuous with the periphery of the skirt part 4.
On the outer periphery, there are 1st, 2nd and 2nd circles in order from the top. third ring groove 81,
8□, 83 are engraved, and the 1st. Second ring groove 81, 8□
A compression ring is attached to the third ring groove 83, and an oil ring (both not shown) is attached to the third ring groove 83.

As shown in FIGS. 1, 3 to 5, notches 9, 9 are provided in the skirt portion 4 at portions adjacent to both sides of each pin boss portion 3 in the circumferential direction.
The bottom surfaces 9a, 9a are inclined upward toward the piston axis Y so that the thrust load receiving surface 4a of the skirt portion 4 follows an isobar line assumed when receiving a thrust load from the inner wall of the cylinder of the engine. It's a shame.

The pin boss portion 3 and the skirt portion 4 are connected to the bottom surface 9 of the notch 9.
They are integrally connected by a rib 10 extending along the direction a, and a through hole 11 is bored in the rib 10 so that the inside of the notch 9 communicates with the inside of the skirt portion 4.

Furthermore, a four part 12 is provided on the lower surface of the ring heald 7 facing the notch 9, and this four part 12 is formed to a depth that reaches the back side of the third ring groove 83. 9 and is formed by casting.

Next, the operation of this embodiment will be explained.

When the piston 1 is reciprocating in the cylinder of the engine, if the piston 1 is oscillated in the counterclockwise direction as shown in FIG. A thrust load from the inner wall of the cylinder is applied to the thrust load receiving surface 4a, and the load is greatest at the lower end of the skirt portion 4 and decreases as it goes upward and in the circumferential direction. Equal pressure line,
will draw a curve similar to a chevron parabola.

By the way, the notches 9, 9 provided in the skirt portion 4 on both sides of each pin boss 3 are located at their bottom surfaces 9a.

Since the notches 9a are formed obliquely with respect to the piston axis Y along the isobars line, the notches 9, 9 can be expanded to the maximum while giving a sufficient effective area to the thrust load receiving surface 4a of the skirt portion 4. Thus, the weight of the piston 1 can be effectively reduced.

Moreover, the thrust load applied to the skirt portion 4 is transmitted and supported to the pin boss portion 3 via the ribs 10, 10 located on the bottom surfaces 9a, 9a of the notches 9, 9.
Despite the presence of this structure, deformation of the skirt portion 4 can be prevented as much as possible.

On the other hand, the lubricating oil interposed between the thrust load receiving surface 9a and the cylinder inner wall is pushed in a direction perpendicular to the isobars, from a place where a large thrust load acts to a place where a small thrust load acts, and is quickly transferred to the notches 9, 9. A part of the oil enters the recesses 12, 12 on the lower surface of the head part 2, effectively cooling the ring belt 7 from the back side of the third ring groove 83, and the other part enters the pin hole. 5 to lubricate the piston pin, and most of the remaining oil is discharged into the hollow part of the piston 1 through the through hole 11 of the rib 10, effectively cooling the piston 1 from the inside.

Further, oil directly scraped from the cylinder inner wall to each notch 9 by an oil ring (not shown) attached to the third ring a83 also follows the same path as described above.

C1 Effects of the invention As described above, according to the present invention, a recess reaching the back side of the ring groove is provided on the lower surface of the head facing the notch, so that the lubricating oil collected from the inner wall of the engine cylinder into the notch is transferred to the head. By infiltrating the four parts of the lower surface, it can effectively cool the head part from the inside, and by extension, it can also cool the piston ring attached to the nod part, which can be expected to improve the durability of the piston and piston ring. At the same time, the weight of the piston can be reduced by the recess.

Moreover, the recess can be formed by casting together with the notch, and the casting of the piston will not be difficult.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a front view of the piston, FIG. 2 is a plan view of the same, FIG. 3 is a side view of the piston, and FIG. 4 is taken along the line IV-IV of FIG. The cross-sectional view, FIG. 5, is a cross-sectional view taken along the line ■-■ in FIG. Y...Piston axis, 1...Piston, 2...Head part, 3...Pin boss part, 4...Skirt part, 83, 8□, 83...Ring groove, 9... Notch, 9a... Bottom, 12... When recessed Applicant: Honda Motor Co., Ltd.] 22''' Fig. 1 @ Fig. 2 Fig. 3

Claims (1)

[Claims] It consists of a head portion having a ring groove on the outer periphery, a pair of pin boss portions that are integrally protruded from the lower surface of the head and lined up coaxially across the piston axis, and a skirt portion that is integrally continuous with the lower periphery of the head portion. A piston having a notch in a portion of the skirt portion adjacent to the pin boss portion, characterized in that a recessed portion reaching the back side of the ring groove is provided on the lower surface of the head portion facing the notch.