Piston for internal combustion engines

Patent metadata

Field	Value
Publication number	US-9828938-B2
Application number	US-201615163405-A
Country	US
Kind code	B2
Filing date	May 24, 2016
Priority date	May 25, 2015
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A resin coat film 39 formed on a skirt portion 10 of a piston 7 has a four-sided outer peripheral region knurled at upper and lower regions thereof corresponding in a rear view of the piston 7 to an upper skirt part 36 and a lower skirt part 38 of the skirt portion 10 extending in parallel with an axial direction of left and right piston pin boss portions 15 and 14 , with a combination of short vertical grooves 43 A and 43 B and medium-length vertical grooves 42 A and 42 B extending in parallel with a central axis C of a piston crow portion 9 , and at left and right edge regions thereof, with long vertical grooves 41.

First claim

The invention claimed is:

1. A piston for internal combustion engines comprising:
a piston body;
a pair of skirt portions hanging down from the piston body;
a pair of piston pin boss portions hanging down from the piston body and configured to hold a piston pin;
a pair of side wall portions configured to interconnect the pair of skirt portions and the pair of piston pin boss portions; and
a resin coat film provided on an outer periphery of one skirt portion of the pair of skirt portions,
the one skirt portion comprising:
a central skirt part having an outside diameter thereof maximized at a central part thereof with respect to an extending direction of a central axis of the piston body;
an upper skirt part residing above an upper boundary of the central skirt part, and curved to have an outside diameter thereof gradually decreased, as the upper skirt part extends from the upper boundary toward the central axis of the piston body; and
a lower skirt part residing below a lower boundary of the central skirt part, and curved to have an outside diameter thereof gradually decreased, as the lower skirt part extends from the lower boundary toward the central axis of the piston body,

the one skirt portion being configured to have increased curvatures, as the one skirt portion circumferentially extends from a circumferential central region on the one skirt portion toward the pair of side wall portions,
the resin coat film comprising a region thereon corresponding to a combination involving at least the upper skirt part and the lower skirt part, the region on the resin coat film being knurled with a set of vertical grooves extending in parallel with the central axis of the piston body,
the set of vertical grooves residing within an outer peripheral range of the resin coat film corresponding to extending directions of the pair of piston pin boss portions with respect to a direction perpendicular to the central axis of the piston body.

2. The piston for internal combustion engines according to claim 1 , wherein the set of vertical grooves comprises a first subset thereof involving first and second vertical grooves mutually neighboring in a circumferential direction of the one skirt portion, the first vertical groove being nearer to the circumferential central region of the one skirt portion and shorter in the extending direction of the central axis of the piston body, than the second vertical groove.

3. The piston for internal combustion engines according to claim 2 , wherein the set of vertical grooves has the first subset thereof residing in a first outer peripheral region of the resin coat film corresponding to the upper skirt part of the one skirt portion.

4. The piston for internal combustion engines according to claim 3 , wherein the set of vertical grooves comprises a second subset thereof involving third and fourth vertical grooves mutually neighboring in the circumferential direction of the one skirt portion, the third vertical groove being nearer to the circumferential central region of the one skirt portion and shorter in the extending direction of the central axis of the piston body, than the fourth vertical groove, wherein the set of vertical grooves has the second subset thereof residing in a second outer peripheral region of the resin coat film corresponding to the lower skirt part of the one skirt portion.

5. The piston for internal combustion engines according to claim 1 , wherein the set of vertical grooves comprises vertical grooves having depths thereof within a range of 5 μm to 20 μm.

Assignees

• Suzuki Motor Corp
• Univ Shizuoka Nat Univ Corp

Inventors

• Suda Naoyuki
• Hayakawa Kunio

Classifications

• F05C2225/00

  Synthetic polymers, e.g. plastics; Rubber · CPC title

• F02F3/10 Primary

  having surface coverings (F02F3/02 takes precedence) · CPC title

• F02F3/00 Primary

  Pistons · CPC title

• F02F3/28

  Other pistons with specially-shaped head · CPC title

• F02F3/022

  the pistons having an oval circumference or non-cylindrical shaped skirts, e.g. oval (F02F3/025, F02F3/027 take precedence) · CPC title