Light plunger piston for internal combustion engines

• US 5,158,008 A
• Filed: 06/24/1991
• Issued: 10/27/1992
• Est. Priority Date: 12/24/1988
• Status: Expired due to Term

• Current Assignee: Mahle GmbH (MAHLE-STIFTUNG GmbH)
• Original Assignee: Mahle GmbH (MAHLE-STIFTUNG GmbH)
• Inventors: Ellermann, Jurgen, Ripberger, Emil
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): Mattingly, Todd
• Application Number:
  US07/688,583
• Time in Patent Office: 491 Days
• Field of Search: 92/177, 92/208, 92/222, 92/225, 92/226, 92/227, 92/228, 92/229, 92/230, 92/233, 92/234, 92/235, 123/193 P
• US Class Current: 92/177
• CPC Class Codes: F02B 1/04 with fuel-air mixture admission into cylinder
• CPC Class Codes: F02F 3/022 the pistons having an oval circumference or non-cylindrical shaped skirts, e.g. oval F02F3/025, F02F3/027 take precedence
• CPC Class Codes: F02F 3/025 having circumferentially slotted piston skirts, e.g. T-slots

Abstract

A piston having a head with ring grooves, a skirt having hub bores, and a pin, with the following dimensions:

L/D=0.45-0.8

H/D=0.25-0.5

A/D=0.3-0.5

T/D=0.45-0.8

where

L=maxium length of the piston

D=maximum diameter of the piston

H=compression height

A=maximum skirt height below the bottom ring groove in a peripheral area having the approximate same skirt height of at least 45 degrees on the major thrust face of the piston with approximately symmetrical division of this area on both sides of a plane extending perpendicular to the pin axis and passing through the longitudinal axis of the piston,

T=diametrically opposite distance between the hub bore ends located radially on the outside.

The skirt bulges along the axis of the piston and has an oval cross-section. An axis of the hub bores is offset slightly towards the major thrust face. The piston includes a horizontal slit, which separates the head from the skirt. In a polar plane perpendicular to the piston axis the skirt has a greater ovality on the minor thrust face. The minor thrust face side of the skirt is structured to bulge less in its upper area, adjacent to the bottom ring groove. The skirt is longer on the major thrust face. The wall thickness is greater on the major thrust face.

Claims

1. A light plunger piston for internal combustion engines, especially gasoline engines for passenger automobiles, comprising

a piston having a head with ring grooves, a skirt having hub bores and a pin, wherein

L/D=0.45-0.8

H/D=0.25-0.5

A/D=0.3-0.5

T/D=0.45-0.8

where

L=maximum length of the piston

D=maximum diameter of the piston

H=compression height

A=maximum skirt height below the bottom ring groove in a peripheral area having the approximate same skirt height of at least 45 degrees on the major thrust face of said piston with approximately symmetrical division of this area on both sides of a plane extending perpendicular to the pin axis and passing through the longitudinal axis of said piston,

T=diametrically opposite distance between the hub bore ends located radially on the outside, and wherein

said skirt bulging along the axis of the piston and having an oval cross-section, with the large diameter of the oval oriented perpendicular to the pin axis;

an axis of the hub bores being offset slightly towards the major thrust face;

said piston includes a horizontal slit, which separates the head from the skirt, located on the minor thrust face side of a plane extending through the longitudinal axis of said pin, and said piston;

said skirt having greater ovality on the minor thrust face side than on the major thrust face side in a polar plane perpendicular to the piston axis;

the minor thrust face side of said skirt being structured to bulge less in its upper area, adjacent to the bottom ring groove, than the major thrust face;

said skirt being longer on the major thrust face than on the minor thrust face; and

the wall thickness of the piston on the major thrust face being greater than on the minor thrust face.

2. The plunger piston according to claim 1, additionally including a first expansion-controlling insert located in the area of the minor thrust face, said insert is formed as a strip extending in the direction of the skirt periphery and having a heat expansion coefficient which is less than that of said skirt.

3. The plunger piston according to claim 1, additionally including a second expansion-controlling insert located in the area of the major thrust face having a greater distance from the upper end of said skirt than said first insert.