Expansible chamber devices – Piston – With ported chamber in piston part for circulating heat...
Reexamination Certificate
1999-08-16
2001-12-11
Ryznic, John E. (Department: 3745)
Expansible chamber devices
Piston
With ported chamber in piston part for circulating heat...
C092S231000
Reexamination Certificate
active
06327962
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a piston for an internal combustion engine and more particularly to a one piece piston having a supporting piston skirt.
BACKGROUND ART
An efficient, light weight, compact, increased horsepower internal combustion engine is sought after by those involved in the industry. To achieve this it is necessary to push the engine design toward its mechanical limits. Increasing combustion pressures in the combustion chamber requires higher combustion temperatures, faster piston speeds and increased mechanical forces. As a result, the piston and associated components are placed under greater stress.
In order to perform satisfactorily and live in such an environment it is necessary to provide a piston that has improved cooling capabilities, increased strength, and a short compression height for reduced mass and light weight. It is also important that such a piston is easy to manufacture with a high level of quality.
It is known to provide a piston with a closed piston cooling gallery. An example of this is shown in U.S. Pat. No. 4,581,983, dated Apr. 15, 1986, to Horst Moebus. The closed piston cooling gallery of Moebus is provided by welding a top portion of the piston to a bottom portion of the piston along a planar surface. The top and bottom portions of the piston each have a portion of the cooling gallery disposed therein. This piston has an excessively tall compression height making it heavy and unsuitable for high speed operation. This piston is also difficult to manufacture and does not have the strength to withstand the increased stresses of the higher combustion pressures. The closed piston cooling gallery as configured in Moebus does not provide a height sufficient to permit adequate shaking of the cooling fluid within the closed piston cooling gallery. Therefore, the efficiency of cooling of the piston is inadequate.
It is also known to provide a piston with decreased mass by reducing height. An example of this is shown in U.S. Pat. No. 4,727,795, dated Mar. 1, 1988, to Edward J. Murray. The short piston height is achieved by intersecting the ring band with the pin bores. This ring band intersection is unacceptable in a high piston speed engine, as leakage and wear in the region of the ring band would be excessive. Additionally, such a piston would not survive the high piston speeds because of insufficient cooling of the piston top portion. Further, the piston skirt, when welded to the piston top, does not permit removal of a pin in the pin bore and therefore makes assembly difficult and would not be a suitable choice. Additionally, providing a piston skirt that is removably attached to the piston reduces strength and further restrict the possibility of use in the proposed high speed, high temperature and high combustion pressure environment.
U.S. Pat. No. 5,778,846, dated Jul. 14, 1998, to Siegfried Mielke discloses a forged or cast piston head of an articulated (two piece) piston. The ring band of the piston is welded to a top portion of the piston. Because this piston does not have a closed cooling gallery or a supported ring band it would not be suitable for use in a high piston speed, high temperature and high compression pressure environment. The higher forces applied to the piston would cause the unsupported ring band to deflect. This would result in unacceptable blowby leakage and premature stress failure of the piston. Further, the piston cooling would be inadequate and would result in a thermal related structural failure of the piston.
The present invention is directed to overcoming one or more of the problems set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention, a one piece piston has a piston body with a top surface and a longitudinal axis. A support portion extends in a direction longitudinally from the piston body. A first pin boss and a second pin boss is connected to the support portion. The first and second pin bosses are spaced apart and each have a pin bore. Each of the pin bores have a bore axis and are axially aligned with each other. The bore axes are oriented transverse to the longitudinal axis. A flange portion is connected to the piston body at a preselected location between the top surface and the pin bore. The flange portion extends radially from the piston body. A piston skirt has first and second skirt portions. The first and second skirt portions are each connected to said flange portion and said support portion. The piston skirt supports the flange portion on the support portion.
In another aspect of the present invention, a one piece piston for an internal combustion engine having a cylinder and a cylinder bore is provided. The one piece piston is disposed in the cylinder bore and is adapted to reciprocally move in the cylinder bore. The one piece piston includes a piston body having a top surface, a longitudinal axis, and a support portion extending in a direction longitudinally from the piston body. A first pin boss and a second pin boss are connected to the support portion. The first and second pin bosses are spaced apart. Each of the pin bosses having a pin bore. Each of the pin bores have a bore axis and are axially aligned with each other. The bore axes are oriented transverse to the longitudinal axis. A flange portion is connected to the piston body at a preselected location between the top surface and the pin bore. The flange portion extends radially from the piston body. A piston skirt has first and second skirt portions. The first and second skirt portions each are connected to the flange portion and the support portion. The first skirt portion is spaced from and opposite the second skirt portion. The first and second skirt portions extend from the flange portion in a substantially axial direction relative to the longitudinal axis. The first and second skirt portions each have first and second spaced end portions. The first and second skirt portions each extending between the first and second pin bosses and are each connected at the first end portion to the first pin boss and at the second end portion to the second pin boss. The piston body, the support portion, the flange portion, and the piston skirt are forged in one piece from a steel material. A ring belt portion is disposed about the piston body. The ring belt portion is connected to the piston body and to the flange portion by welding. A piston cooling gallery is disposed annularly in the piston body. The piston cooling gallery is closed by the flange and ring belt portions to define a closed piston cooling gallery.
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patent: 6155157 (2000-12-01), Jarrett
Caterpillar Inc.
Hickman Alan J.
Ryznic John E.
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