DE102009036240A1 - Compression piston ring - Google Patents

Abstract

Compression piston ring, comprising a tread region, upper and lower flanks and an inner circumferential surface, wherein the tread region is provided with a profiling, characterized in that the profiling, seen from the axial height of the tread region, spaced from each other, approximately convex spherical, each having a vertex comprising portions including a groove of predeterminable depth therebetween, wherein the compression piston ring has a centroid which lies in the axial direction in a plane between the vertices.

Description

The The invention relates to a compression piston ring including one Tread area, upper and lower flanks and a inner peripheral surface, wherein the tread area is provided with a profiling.

Compression piston rings on the one hand to achieve a small blow by be designed so that a high tightness over the Combustion chamber is given. This is achieved by the vertex the crown in the axial direction as far as possible in the direction the upper piston ring flank is placed.

Around at the same time, however, realize a low oil consumption, the compression ring should be as sharp as possible, this requires the apex of the crown in the axial direction as far as possible in the direction of the lower piston ring flank be placed.

by virtue of These conflicting demands may be the interpretation of the Compression piston ring always represent only a compromise.

Of the DE 199 44 453 C1 is a piston ring for the combustion chamber facing first groove of a piston to refer to internal combustion engines, with a spherical tread, wherein the apex of the crown is arranged by more than half the piston ring height below the combustion chamber side piston ring flank, wherein on the tread a groove is arranged, the extends in the axial direction of the combustion chamber remote from the lower piston ring edge to the apex of the crown. The radial depth of the groove should here be formed <0.5 mm.

By the DE 44 29 649 A1 a piston ring with a crowned tread and with the cylinder wall in contact bearing area has become known, which terminates in two tread edges, wherein the apex of the crown is disposed inside or below the piston ring center. The bearing area of the tread has at the edges a radius of curvature which is at least three times greater than the radius of curvature at the apex.

The The prior art describes compression piston rings unable to meet the criteria set out above, namely a low blow-by while achieving a low oil consumption, Take into account.

Of the Invention is based on the object of providing a compression ring on the one hand has a good seal against the combustion chamber and on the other hand also brings about a good Ölabstreifwirkung.

These The object is solved by the features of claim 1.

advantageous Further developments of the compression piston ring according to the invention are to be found in the associated subclaims.

advantageously, has the vertex of the upper flank facing upper Section a larger indentation than the one lower flank facing, vertex of the lower section.

The crowned sections are related to the axial height of the Tread portion, provided asymmetrically to each other, where the vertex of the lower section is in the range of 0 to 25% and the vertex of the upper section in the range of 50 to 75% of the axial height of the tread area is positioned.

According to a further aspect of the invention, it is proposed that the entry of the upper section (t ₃ ) is in the range between 20 and 40 μm, while the entry of the lower section (t ₂ ) is between 1 and 5 μm.

advantageously, is provided between the approximately convex portions Groove approximately concave and has, based on an investment area of Vertices on a mating surface, a radial depth which corresponds approximately to the depth of the intake of the upper section.

Of the Subject of the invention is based on an embodiment shown in the drawing and is described as follows. It demonstrate:

1 Schematic diagram of a compression piston ring according to the invention in the resting state;

2 Principle sketch according to 1 when pressurized from the combustion chamber area;

3 Representation of the piston ring according to 1 in the upstroke.

4 Representation of the piston ring according to 1 with undesirable twist behavior.

In 1 is an inventive compression piston ring 1 shown including a tread area 2 , an upper flank facing the combustion chamber B. 3 , a lower edge facing the oil space O 4 and an inner peripheral surface 5 , To the left of the compression piston ring 1 is the Y-axis, ie the axial height of the piston ring 1 , respectively the tread area 2 , darge provides. The dimension starts at the level of the lower flank 4 and ends at the height of the upper flank 3 ,

According to the invention, the tread area 2 two approximately convex shaped spherical sections 6 . 7 on, each forming a vertex B1, B2. Between the respective vertexes B1, B2 of the crowned sections 6 . 7 extends an approximately concave recess B. By reference numeral 9 is a mating surface, such as a cylinder liner, addressed.

The investment point 10 of the upper vertex B1 on the mating surface 9 is in the range between 50 and 75% of the axial height of the tread area 2 , The investment point 11 of the lower vertex B2 on the mating surface 6 / 9 is between 1 and 25% of the axial height of the tread area 2 ,

In any case, it must be ensured that the centroid S of the piston ring cross-section - based on the axial height of the tread area 2 - lies in a plane between the two vertices B1, B2. This ensures that in the static state of the piston ring 1 due to its radial force F _rad1 , F _rad2 with both vertexes B1 and B2 at the _{mating surface} 9 is applied. The radial force will be divided into B1 and B2 according to the law of levers. In the illustration according to 1 is F _rad1 > F _rad2 .

The feeder t3 of the combustion chamber B facing upper spherical portion 6 can be in the range of 20 to 40 microns to allow in the upstroke a good floating on the oil film. The indent t2 of the vertex B2 of the lower crowned section 11 can be between 1 and 5 microns, the formula applies, the sharp-edged, the better the Ölabstreifwirkung.

The 2 to 4 show the behavior of the piston ring according to the invention 1 in engine operation. 2 shows the downward stroke - power stroke.

Since the upper vertex B1 is very high up, namely above the average axial height of the piston ring 1 ( 1 ), the gas pressure is only a small attack surface on the tread area 2 of the piston ring 1 to disposal. The formula applies F _gas = P _gas × A

Consequently, there is also a smaller force that the piston ring 1 from the mating surface 9 wants to take off.

3 shows the upstroke - compression / ejection. Here it is desirable that the piston ring 1 floating on the remaining oil in the combustion chamber B oil film to pass the oil residues in the crankshaft space. The strong indent t3 and the recess t4 ( 1 ) between the vertices B1, B2 facilitates the floating. In addition, the radial force F _{rad is distributed} in two places (F _rad1 and F _rad2 ). This reduces the surface pressure per bearing point (p01 / p02). The piston ring 1 can thus float more easily.

4 shows a rather undesirable condition of the piston ring behavior in engine operation.

Unexpectedly, the piston ring should 1 vertwisten and lift off the top vertex B1, then lies the piston ring 1 still at the lower vertex B2 and seals against the combustion chamber B. A useful effect here is that the vertex B1 acts as a throttle and thus slows down the gas flow. For the oil consumption has a favorable effect that the vertex B2 - based on the axial height of the piston ring 1 - is very low and the feeder t2 is kept very small. This creates a quasi-sharp scraping edge.

Because the piston ring 1 is present at both vertices B1, B2, a supporting mirror will form at both vertices. If the piston ring 1 not vertwistet, the supporting mirror will be cylindrical.

During the power _stroke, the gas pressure counteracts the force F _rad1 at the vertex B1, while the vertex B2 serves as a support.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19944453 C1 [0005]
• - DE 4429649 A1 [0006]

Claims (8)

Compression piston ring, including a tread area ( 2 ), upper and lower flanks ( 3 . 4 ) and an inner peripheral surface ( 5 ), the tread area ( 2 ) is provided with a profiling, characterized in that the profiling, on the axial height of the tread area ( 2 ), spaced-apart, approximately convex spherically formed, each having a vertex (B1, B2) having sections ( 6 . 7 ), which has between it a groove ( 8th ) of predeterminable depth (t4), wherein the compression piston ring has a centroid (S) lying in the axial direction in a plane between the vertices (B1, B2). Piston ring according to claim 1, characterized in that the vertex (B1) of the upper flank (B1) 3 ) facing upper portion ( 6 ) has a larger intake (t3) than that of the lower flank ( 4 ) facing vertex (B2) of the lower section ( 7 ) having. Piston ring according to claim 1 or 2, characterized in that the crowned sections ( 6 . 7 ), based on the axial height of the tread area ( 2 ) are arranged asymmetrically to each other. Piston ring according to one of claims 1 to 3, characterized in that the vertex (B2) of the lower portion ( 7 ) in the range of 1 to 25% and the vertex (B1) of the upper portion ( 6 ) in the range of 50 to 75% of the axial height of the tread area ( 2 ) is positioned. Piston ring according to one of claims 1 to 4, characterized in that the indentation (t3) of the upper portion ( 6 ) is in the range between 20 and 40 microns. Piston ring according to one of claims 1 to 5, characterized in that the indentation (t2) of the lower portion ( 7 ) is in the range between 1 and 5 microns. Piston ring according to one of claims 1 to 6, characterized in that between the approximately convex portions ( 6 . 7 ) groove ( 8th ) is approximately concave and related to an investment area ( 10 . 11 ) of the vertices (B1, B2) on a mating surface ( 9 ), a depth (t4) that corresponds approximately to the indentation (t3). Piston ring according to one of claims 1 to 7, characterized in that the vertices (B1, B2) in the same radial plane lie.

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