Closed gallery piston having reinforced oil hole

Internal-combustion engines – Particular piston and enclosing cylinder construction – Piston

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C092S186000

Reexamination Certificate

active

06491013

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates generally to pistons for diesel engine applications, and more particularly to those having a closed oil gallery.
2. Related Art
It is known in diesel engine applications to provide a piston whose piston body is formed with a closed gallery for cooling oil. The oil circulates through the gallery and cools parts of the piston which are susceptible to damage from the heat of combustion. Such cooling galleries are generally annular or ring-shaped and are provided just inside of the ring belt adjacent the top wall of the piston body. The gallery is bounded by an inner wall and closed at the bottom by a bottom wall. A plurality of access openings are typically provided in the bottom wall for allowing the oil to flow into and out of the gallery. Such oil holes are typically bored in the bottom wall. While such holes are necessary in order to provide for the inflow and outflow of oil to the gallery, such holes present an abrupt discontinuity in the bottom structure of the gallery. Because of the closed gallery structure, the forces exerted by the cylinder pressure on the top wall of the piston are transmitted through not only the inner wall to the pin bosses of the piston, but as well through the outer ring belt and bottom wall to the pin bosses. The presence of the oil holes in the bottom wall, which is structural and load-bearing, sets up a stress concentration point as the loads are transmitted through the outer ring belt and bottom wall regions of the piston. Presently, it is necessary to provide sufficient thickness to the bottom wall and ring belt portions of the piston crown to accommodate stresses that might otherwise lead to failure. Such material, while necessary, adds cost and weight to the piston.
It is an object of the present invention to overcome or greatly minimize the shortcomings of the prior pistons described above.
SUMMARY OF THE INVENTION AND ADVANTAGES
A closed gallery piston for diesel engines constructed according to the invention comprises a piston body having a top wall, an outer wall formed with ring grooves, an inner wall spaced radially inwardly from the outer wall, and a bottom wall interconnecting the outer wall and inner wall, with the walls providing an enclosed annular gallery for cooling oil. A pair of pin boss portions are provided having aligned pin bores. At least one oil access hole is formed in the bottom wall. An oil hole boss defined by a locally thickened portion of the bottom wall boarders the oil hole.
The invention has the advantage of providing a reinforced oil hole structure to a closed gallery piston which provides structural integrity in the region of the oil hole to counteract localized stress concentration which is present due to the hole in the bottom wall.
The invention has a further advantage of forming the reinforcing oil hole boss by way of a locally thickened region of the bottom wall of the gallery, which has the advantage of enabling the remainder of the bottom wall to be decreased in thickness as it is no longer needed to make up for the localized stress induced by the presence of the oil hole. By having only a locally thickened portion bordering the oil hole, a corresponding decrease in the thickness of the remainder of the bottom wall decreases the total material and thus weight and cost of the piston.
The invention has the further advantage of enabling the manufacturer of pistons to engineer the size and shape of the oil hole boss to provide the necessary structural support to counteract the stress concentration effects of the hole while minimizing the overall thickness of the bottom wall and surrounding structure adjacent the hole.


REFERENCES:
patent: 4011797 (1977-03-01), Cornet
patent: 4180027 (1979-12-01), Taylor
patent: 4331107 (1982-05-01), Bruni
patent: 4375782 (1983-03-01), Schieber
patent: 4581983 (1986-04-01), Moebus
patent: 4608947 (1986-09-01), Stadler
patent: 4662319 (1987-05-01), Ayoul
patent: 4776075 (1988-10-01), Kawabata et al.
patent: 5052280 (1991-10-01), Kopf et al.
patent: 5144923 (1992-09-01), Leites et al.
patent: 5413074 (1995-05-01), Horiuchi
patent: 5483869 (1996-01-01), Bock et al.
patent: 5595145 (1997-01-01), Ozawa
patent: 5692430 (1997-12-01), McLaughlin et al.
patent: 5778533 (1998-07-01), Kemnitz
patent: 5794582 (1998-08-01), Horiuchi
patent: 5913960 (1999-06-01), Fletcher-Jones
patent: 5934174 (1999-08-01), Abraham, Sr. et al.
patent: 5979298 (1999-11-01), Whitacre
patent: 6003479 (1999-12-01), Evans
patent: 6032619 (2000-03-01), Zhu et al.
patent: 6152016 (2000-11-01), Bahr et al.
patent: 6314933 (2001-11-01), Iijima et al.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Closed gallery piston having reinforced oil hole does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Closed gallery piston having reinforced oil hole, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Closed gallery piston having reinforced oil hole will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2987220

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.