CN107842437B

CN107842437B - Piston with support structure below crown

Info

Publication number: CN107842437B
Application number: CN201711058426.2A
Authority: CN
Inventors: 库尔特·威尔; 马克·伯兰特; 麦克·特伯
Original assignee: Federal Mogul LLC
Current assignee: Federal Mogul LLC
Priority date: 2011-06-29
Filing date: 2012-06-28
Publication date: 2020-03-06
Anticipated expiration: 2032-06-28
Also published as: JP6226866B2; KR20140032455A; JP2017115894A; EP2726724A1; JP2014521000A; EP2726724B1; JP6396521B2; WO2013003546A1; CN103748345A; CN107842437A

Abstract

The present invention provides a piston having a piston body extending along a longitudinal central axis and having a crown portion and a pair of pin bosses. The crown includes a combustion wall with a combustion bowl formed therein, and a pair of ribs depending from the combustion wall. One of the ribs depends from the combustion wall directly below the combustion bowl and the other of the ribs is spaced radially from the combustion bowl. Thus, one of the ribs depends lower along the longitudinal central axis than the other rib. The ribs provide support for the crown while also acting as heat sinks to dissipate the heat from the combustion wall.

Description

Piston with support structure below crown

The application is a divisional application of 'piston with supporting structure under crown' with application date being 2012, 6 and 28 and China application number being 'CN 201280037963.8' (International application number being PCT/US 2012/044564).

Cross Reference to Related Applications

This application claims benefit of U.S. provisional application serial No.61/502,602 filed on 29/6/2011.

Technical Field

The present invention relates generally to pistons for internal combustion engines.

Background

In an ongoing effort to improve power production and fuel efficiency, many engine manufacturers are adopting advanced technologies such as direct injection, turbochargers, and superchargers in gasoline fueled engines. Generally, these and other advanced technologies improve engine performance by increasing the pressure and temperature within the cylinder bores of the engine. However, the increased pressure and temperature may cause undesirable bending or other damage to the upper crown of the piston of the engine. Such damage may result in reduced performance or even complete failure of the engine.

To enhance the ability of the engine's pistons to withstand increased combustion pressures and temperatures, some piston manufacturers have begun producing pistons with thickened combustion walls. While such pistons may resist bending at increased pressures and temperatures, the increase in thickness adds weight to the piston, which may detract from the power and fuel efficiency improvements derived from advanced technology.

Disclosure of Invention

According to one aspect of the present invention, a piston is provided having a piston body extending along a longitudinal central axis. The piston body has a crown with a combustion wall and a pair of pin bosses depending from the crown. The crown includes at least two integrally formed ribs, each depending from the combustion wall. One of the ribs depends (extends) lower along the longitudinal central axis than the other rib. The ribs increase the bending strength of the upper crown about the pin bore axis without substantially increasing the weight of the piston. In addition, the ribs act as fins to dissipate heat from the combustion wall, thereby cooling the piston.

In accordance with another aspect of the invention, the ribs extend between the pin bosses and are bent outwardly from the pin bore axis. Thus, the length of the ribs is increased without substantially increasing the weight of the piston.

According to yet another aspect of the present invention, a piston is provided having a piston body extending along a longitudinal central axis and having a crown with a combustion wall and a pair of pin bosses depending from the crown. The combustion wall includes at least one combustion bowl formed therein, and the crown includes at least one integrally formed rib depending from the combustion bowl directly below the at least one combustion bowl. Thus, the at least one rib enhances the strength of the upper crown at the location of the combustion bowl, which is often located in the combustion center of the cylinder bore.

Drawings

To more clearly illustrate these and other aspects, features and advantages of the present invention, those skilled in the art will hereinafter describe the present invention in conjunction with the presently preferred embodiments and best mode, the appended claims and the accompanying drawings, in which:

FIG. 1 is a perspective view of a piston constructed in accordance with one aspect of the invention;

FIG. 2 is a side view of the piston of FIG. 1;

FIG. 3 is a bottom view of the piston of FIG. 1;

FIG. 4 is a cross-sectional view taken generally along line 4-4 of FIG. 3; and

fig. 5 is a cross-sectional view taken generally along line 5-5 of fig. 3.

Detailed Description

Referring to the drawings, wherein like numerals are used to indicate corresponding parts throughout the different views, there is shown in FIGS. 1-5 a piston 20 constructed in accordance with one presently preferred aspect of the invention. The piston 20 of the exemplary embodiment is integrally formed, preferably cast to near net shape and then machined to its final dimensions. However, it should be understood that the piston 20 may alternatively be constructed from multiple components that may be formed and connected to one another by any desired method. The piston 20 is preferably formed of an aluminum alloy, but may alternatively be formed of steel or any desired metal or alloy.

As shown in FIG. 1, the exemplary one-piece piston 20 has a longitudinal central axis A₁An extended piston body 22 having an upper crown portion 24, a pair of pin bosses 26 and a pair of skirt portions 28. The upper crown 24 includes a combustion wall 30 and a plurality of annular grooves 32 axially spaced from the combustion wall 30 for receiving piston rings (not shown). The pin bosses 26 are oriented along a longitudinal central axis A₁Extending downwardly from the upper crown 24. Each pin boss 26 has a pin bore 34, the pin bores 34 being along a pin bore axis A₂(as shown in fig. 3) are aligned with each other for receiving a piston pin (not shown) to interconnect the piston 20 and the small end of the connecting rod (not shown). As shown in fig. 3, two skirts 28 are provided diametrically opposite each other, each skirt 28 extending between and interconnecting the pin bosses 26. When the engine is running, the piston body 22 is along the longitudinal central axis A within the engine block (not shown)₁And reciprocates to rotate a crankshaft (not shown) via a connecting rod (not shown).

Referring back to FIG. 1, the combustion wall 30 includes a generally planar portion, a convex portionA start portion (pop-up) and a combustion bowl 36 formed therein. The combustion bowl 36 is configured relative to a longitudinal central axis A₁Asymmetrical, i.e. the centre of the combustion bowl 36 is not arranged along the longitudinal centre axis A₁. However, it should be understood that the combustion bowl 36 may alternatively be disposed about the central axis A₁And (4) symmetry. When the piston 20 is used in an engine with direct injection technology, combustion of fuel and gases within the cylinder bore tends to concentrate around the combustion bowl 36, thereby creating increased pressure and heat at this location. As a result, the combustion bowl 36 is typically the highest stress region of the crown 24. The exemplary piston 20 has an under crown support structure to strengthen the upper crown 24 against these forces.

Referring now to FIG. 3, the piston 20 includes a pair of

ribs

38, 40 spaced radially from one another and extending generally between the pin bosses 26 to strengthen the upper crown 24 when the combustion wall 30 is exposed to increased pressures and temperatures of an engine having a direct injection, turbocharger and/or supercharger to thereby increase the upper crown 24 about the pin bore axis A₂The bending strength of (2). This increase in bending strength does not substantially result in an increase in the weight of the piston 20. In the exemplary embodiment, each

rib

38, 40 is generally arcuate or radiused to increase the support area under the combustion wall 30 to further enhance the upper crown about the pin bore axis A₂The bending strength of (2). The arcuate shape of the

ribs

38, 40 also allows for substantially smooth mating or interconnection of the

ribs

38, 40 with the opposing pin bosses 26, thereby avoiding unnecessary stress at the intersection of these elements. Referring now to fig. 5, each

rib

38, 40 depends from upper crown 24 and is integrally formed with upper crown 24. Thus, each

rib

38, 40 may be formed "as-cast" with the upper crown portion at low or little additional cost. However, it should be understood that the

ribs

38, 40 may be formed as upper crowns by any suitable method. In addition to stiffening the upper crown against bending, the

ribs

38, 40 may also act as heat sinks to dissipate heat from the upper crown combustion wall 30, thereby cooling the combustion wall 30. This heat dissipation effect further enhances the ability of the piston 20 to withstand increased combustion temperatures. It will be appreciated that alternatively the ribs may be rectilinear orAnd may even be formed in an inwardly curved arc, depending on the requirements of a particular piston design.

Still referring to FIG. 5, the combustion wall 30 of the exemplary piston 20 is formed to have a generally uniform thickness both in the combustion bowl 36 and in the area surrounding the combustion bowl 36, except for the

ribs

38, 40. One of the two ribs 38, 40 (hereinafter referred to as "first rib 38") depends from the combustion wall 30 directly below the combustion bowl 36. Thus, the first ribs 38 are positioned to provide optimal support at the highest stress location of the upper crown 24. Another rib (hereinafter referred to simply as "second rib 40") depends from the combustion wall 30 at a location diametrically opposite the first rib 38 and is spaced from the combustion bowl 36. Since the lower surface of the combustion wall 30 is recessed in the region of the combustion bowl 36, the first rib 38 (located directly below the combustion bowl 36) is recessed relative to the second rib 40, i.e., the first rib 38 extends lower than the second rib 40. Thus, although the first and

second ribs

38, 40 have substantially similar lengths, the underside of the combustion wall 30 has an asymmetric appearance in cross-sectional view. Additionally, because the exemplary combustion bowl 36 has a generally hemispherical shape, the first rib 38 is not only curved away from the pin bore axis A₂Outwardly and perpendicularly toward the pin bosses 26 of the piston body 22.

Referring now to fig. 3, the skirt 28 extends generally concentrically with the

ribs

38, 40. Thus, the skirt 28 and the

ribs

38, 40 have the same or substantially the same radius of curvature. However, it should be understood that the skirt 28 and the

ribs

38, 40 may be non-concentric.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims

1. A piston, comprising:

a piston body extending along a longitudinal central axis and having a crown with a combustion wall and a pair of pin bosses depending from said crown; and

said crown including a pair of ribs integrally formed and depending from said combustion wall, said pair of ribs consisting of a first rib and a second rib, said combustion wall having a hemispherical combustion bowl asymmetrical with respect to said longitudinal central axis, said first rib depending from said combustion wall directly below said combustion bowl, said second rib being radially spaced from said combustion bowl, and wherein said first rib spaced from said longitudinal central axis depends lower in a direction parallel to said longitudinal central axis than said second rib also spaced from said longitudinal central axis; the combustion wall has a uniform thickness in both the combustion bowl and the area surrounding the combustion bowl, except for the pair of ribs; the first and second ribs are each arc-shaped, the arc of which is curved not only outwardly away from the pin bore axis but also perpendicularly toward the pin bosses of the piston body, between which the first and second ribs extend, respectively, the first and second ribs being diametrically opposed to each other.