Piston oil scraper ring

Abstract

The invention relates to a multi-part piston oil scraper ring (1), comprising a slotted spring element and at least one sheet element (3, 4) operatively connected to the spring element and provided with a seam (7), the spring element being designed as a serpentine spring (2) which, on the one hand, accommodates the sheet element axially and, on the other hand, supports the sheet element radially, the two end regions of the serpentine spring being provided with side legs (9, 10) extending approximately parallel to one another, the axial length of the side legs being designed such that the side legs are at least partially embedded in the seam of the sheet element.

Description

Technical Field

[0001] The invention relates to a multi-part piston oil scraper ring comprising a grooved spring element and at least one sheet element operatively connected to the spring element and provided with a seam. Background Art

[0002] The multi-part piston oil scraper ring has the task of preventing engine oil from the crankcase from entering the combustion chamber.

[0003] As exhaust gas regulations become increasingly stringent, the issue of particulate emissions has become particularly important. The starting point is that a significant portion of particulate emissions is caused by abnormal combustion due to the oil entering the combustion chamber. Tests have shown that during engine operation, the negative pressure in the combustion chamber causes a stronger suction of oil from the crankcase toward the combustion chamber.

[0004] WO 2013 / 004217 A2 discloses a piston oil scraper ring for an internal combustion engine piston. The piston oil scraper ring includes at least one sheet element, each having a seam, and a serpentine spacer spring having a seam. The at least one sheet element and the spacer spring are in contact with each other. The seam of the at least one sheet element forms an acute angle with a radius of the at least one sheet element. Preferably, the oil scraper ring includes two sheet elements extending parallel to each other, the spacer spring being disposed between the sheets, and each sheet element having a seam.

[0005] No. 2,469,959 discloses a piston ring, in particular a piston oil scraper ring, which comprises two plate elements, the joint of which is arranged in overlapping fashion, and a spacer spring arranged between the plate elements. Summary of the Invention

[0006] The object of the subject matter of the present invention is to provide a piston oil scraper ring in which the possibility of oil coming from the crankcase entering the combustion chamber is substantially prevented, so that particle emissions can be reduced.

[0007] The object is achieved by a multi-part piston oil scraper ring, which includes a grooved spring element and at least one sheet element operatively connected to the spring element and provided with a seam, the spring element being configured as a serpentine spring which, on the one hand, accommodates the sheet element axially and, on the other hand, supports the sheet element radially, the two end regions of the serpentine spring being provided with side legs extending approximately parallel to each other, the axial length of the side legs being designed so that the side legs are at least partially embedded in the seam of the sheet element.

[0008] The axial length of the limbs of the serpentine spring is here arranged such that the limb ends of the limbs end approximately at the level of the upper side of the disk element.

[0009] According to another concept of the present invention, the serpentine spring cooperates with an upper plate element facing the combustion chamber and a lower plate element facing the oil chamber, wherein the side legs of the serpentine spring engage in the joint of the upper plate element.

[0010] Advantageously, the legs of the serpentine spring are guided with a defined clearance within the joint of the plate elements.

[0011] According to another concept of the present invention, the thickness of the two side legs of the serpentine spring is designed to be smaller than the width of the joint of the sheet element, so that the side legs that fit together are guided inside the joint of the sheet element with a certain gap (as viewed in the circumferential direction) while maintaining the tangential force of the sheet element.

[0012] The novel design of the oil scraper ring according to the present invention provides for the ends of the serpentine spring to be longer in the axial direction, so that they engage with clearance in the existing interspace of the joint end of one of the leaf elements, preferably the leaf element facing the combustion chamber. This closes off any open joints of the leaf elements that could serve as oil passages. This allows less oil from the crankcase to pass toward the combustion chamber, which also reduces particle emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The subject matter of the invention is illustrated and described below with reference to the exemplary embodiments shown in the accompanying drawings, in which:

[0014] FIG1 shows a piston oil scraper ring according to the prior art in different views or cross-sectional views;

[0015] FIG2 shows a schematic diagram of the principle of a piston oil scraper ring according to the invention in different views or sectional views;

[0016] FIG. 3 shows an enlarged view of the seam region to be sealed of the leaf ring according to FIG. 2 . DETAILED DESCRIPTION

[0017] FIG1 shows a piston oil scraper ring 1 according to the prior art in various views or sectional views. The piston oil scraper ring 1 comprises a serpentine spring 2 and two plate elements 3, 4. The serpentine spring 2 is designed so that, on the one hand, an axial receiving area 5 is formed for the respective plate element 3, 4, and, on the other hand, a radial support area 6 is formed for the respective plate element 3, 4. Each plate element 3, 4 is provided with a seam 7, 8. The serpentine spring 2 is designed to be slotted and has two lateral legs 9, 10 extending approximately parallel to one another on the seam side, which are arranged at a specific distance from the upper plate element 3.

[0018] FIG2 shows a piston oil scraper ring 1 ′ according to the present invention. Identical components are denoted by the same reference numerals. The serpentine spring 2 and the plate elements 3 and 4 can be seen. According to the present invention, the length of the side legs 9 and 10 is designed so that they extend at least partially into the joint 7 of the upper plate element 3 with a defined clearance. The maximum length of the side legs 9 and 10 can be designed so that their ends are approximately at the level of the side faces 11 of the upper plate element 3.

[0019] The plate element 3 is intended to face the combustion chamber B (not shown) and the plate element 4 is intended to face the oil chamber O (also not shown).

[0020] In the illustration according to FIG. 1 , an oil flow can occur via the joint 8, the serpentine spring 2 and the joint 7 of the plate element 3 in the direction of the combustion chamber B, while a sealed closure structure is formed by the side legs 9, 10 of the serpentine spring 2 embedded in the joint 7 according to FIG. 2 , by which an axial oil flow can be substantially blocked (see arrows in FIGS. 1 and 2 ).

[0021] FIG3 shows an enlarged view of the sealing area of the upper disc element 3 according to FIG2 . The two legs 9 and 10 of the serpentine spring 2 can be seen here. The joint 7 of the disc element 3 has a predeterminable joint width a. The legs 9 and 10 have the same thickness d and are flat against each other. In this example, the axial ends of the legs 9 and 10 are positioned below the side surface 11 of the upper disc element 3 . To prevent the legs 9 and 10 from being clamped within the joint 7 and to prevent the tangential forces of the disc element 3 from being affected, the two legs 9 and 10 of the disc element are positioned with a certain clearance (as viewed in the circumferential direction) within the joint width a of the joint 7 . This is considered to be a clearance fit typical for shafts. Since piston rings are designed with different diameters for different applications, the clearance fit can be adapted accordingly.

[0022] Reference Signs List

[0023] 1 Piston oil scraper ring

[0024] 1' piston oil scraper ring

[0025] 2 serpentine spring

[0026] 3 components

[0027] 4 components

[0028] 5Accommodation area

[0029] 6 support areas

[0030] 7 seams (sheet elements)

[0031] 8 seams (sheet elements)

[0032] 9 side legs (snake spring)

[0033] 10 side legs (snake spring)

[0034] 11 Side of the upper sheet element

[0035] aSeam width

[0036] d Thickness of the side legs

Claims

1. A multi-part piston oil scraper ring, comprising a grooved spring element (2) and at least one sheet element (3, 4) operatively connected to the spring element and provided with a seam (7, 8), wherein the spring element (2) is configured as a serpentine spring which, on the one hand, accommodates the sheet element (3, 4) in the axial direction and, on the other hand, supports the sheet element in the radial direction, wherein the two end regions of the serpentine spring (2) are provided with side legs (9, 10), the axial length of the side legs being designed such that the side legs (9, 10) are at least partially embedded in the seam (7, 8) of the sheet element (3, 4), and characterized in that: The side legs (9, 10) extend approximately parallel to each other, and the thickness (d) of the two side legs (9, 10) of the serpentine spring (2) is designed to be smaller than the seam width (a) of the sheet element (3), so that the side legs (9, 10) that are in contact with each other are guided with a certain gap inside the seam (7) of the sheet element (3) while maintaining the tangential force of the sheet element (3).

2. The piston oil scraper ring according to claim 1, characterized in that: The axial length of the side legs (9, 10) is arranged such that the side leg ends of the side legs (9, 10) end approximately at the level of the upper side (11) of the sheet element (3, 4).

3. The piston oil scraper ring according to claim 1 or 2, characterized in that: The serpentine spring (2) cooperates with the upper plate elements (3, 4) facing the combustion chamber (B) and the lower plate elements (3, 4) facing the oil chamber (O), wherein the side legs (9, 10) of the serpentine spring (2) engage in the seam (7) of the upper plate element (3).

4. The piston oil scraper ring according to claim 1 or 2, characterized in that: The limbs (9, 10) of the serpentine spring (2) are guided with a defined clearance within the joint (7) of the sheet element (3).

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