Oil scraper ring and piston ring set for internal combustion engines

Abstract

The present invention relates to an oil scraper ring (4) comprising a ring element (6) having an upper ring edge (8), a lower ring edge, an inner ring side and an outer ring side (14), wherein the ring element (6) is provided with two opposing contact surfaces (20) and there is a ring gap (18) between the contact surfaces (20), and the ring element (6) is provided with at least one scraper bar (24, 26) on the outer ring side (14), and the oil scraper ring (4) is also provided with two recesses (28), each of which is disposed in an area of ​​the contact surfaces (20), and each of which is adjacent to each contact surface (20) and the upper ring edge (8) at least on the outer ring side (14).

Description

Technology Field

[0001] The present invention relates to an oil scraper ring inserted into an internal combustion engine, preferably a four-stroke engine, and a piston ring set including said oil scraper ring. The oil scraper ring includes ring gaps that are designed differently at the top and bottom, i.e., on the combustion chamber side and the crankcase side. Background Technology

[0002] Conventionally, oil scraper rings having a constant ring gap are known. These constant ring gaps are generally selected to be as small as possible to achieve maximum oil scraping effect. Although "blow-by" gases must flow through this ring gap, selecting a narrow ring gap results in gas pressure over the ring. This high pressure can cause instability in the second ring and consequently have a negative effect on the functional performance of the entire ring. The problem to be solved

[0003] The present invention is intended to combine the advantages of small ring gaps associated with the oil scraper effect with a larger ring gap that prevents pressure increase and instability in the second ring. Additionally, the present invention is intended to reduce any oil flow in the upward direction, i.e., into the combustion chamber, in throttled mode or overrun mode.

[0004] The present invention relates particularly to operating conditions in which the pressure of the combustion chamber drops below the ambient pressure, thereby reducing the amount of oil that can enter the combustion chamber on one hand, and at the same time reducing the increase in gas pressure or gas pressure difference, thereby increasing the stability of the second or intermediate (oil control) piston ring.

[0005] The larger effective gap at the upper edge of the oil scraper ring enables freer gas flow at high loads when the ring is pressed against the upper piston ring groove edge due to mass or inertial force. When the amount of oil that can enter the combustion chamber is reduced, less oil is burned, and consequently, there is an effect of reducing particle emissions, especially after overrun operation. means of solving the problem

[0006] The oil scraper ring according to the present invention has the features of claim 1, and further advantageous embodiments are described in the dependent claims. According to a further aspect of the present invention, a piston ring set having an oil scraper ring according to the present invention and an additional oil control ring having a specific shape of the ring gap are described.

[0007] In addition, the oil scraper ring of the present invention, having a non-uniform ring gap, is configured to guide a portion of the blow-by into the intermediate space between the two scraper bars of the piston ring, so that a portion of the blow-by flows into the ring groove base through the radial openings of the oil scraper ring, and is then guided to the crankcase through oil drain channels or an underlying axial play. In this case, it should be noted that the blow-by is reduced by the two compression rings located above it to the extent that this drain does not cause significant problems. In particular, through the blow-by flow, oil droplets from the gap between the two oil scraper bars may be mixed and supplied to the crankcase.

[0008] According to an exemplary embodiment of the present invention, an oil scraper ring comprises a ring element having an upper ring edge, a lower ring edge, a ring inner side radially positioned, and a ring outer side radially positioned. The ring element is provided with two contact ends, and a ring gap exists between them. The contact ends have opposing contact surfaces. At least one scraper bar is provided on the ring outer side of the ring element. The oil scraper ring according to the present invention has two (opposing) recesses, each of which is located in the area of ​​the contact ends, and each of which is adjacent to the respective contact surface and the upper ring edge at least on the ring outer side. Thus, each recess extends from a corner formed from the ring outer side or the surface of the bar, in the area where the respective contact surface and the upper ring edge are located. The two opposing recesses located on both sides of the ring gap widen the ring gap, particularly between the edges of the upper scraper bar.

[0009] One of the two recesses is positioned on each contact end. Thus, each recess extends from the outer side of the ring or the surface of the bar, each contact surface, and the area of ​​the upper ring edge. In each case, the recess extends from the upper scraper bar area. This allows the remaining ring gap to be configured to be 2 to 3 times (practically) smaller than possible with conventional rings. The ring gap on the upper edge surface is 2 to 5 times larger than the ring gap in the installed state.

[0010] According to a further exemplary embodiment, the recesses are designed symmetrically with respect to the mirror plane of the contact surfaces. The mirror plane of the contact surfaces is defined in this case by the contact surfaces, wherein the center point and axial direction of the piston ring must be on the mirror plane.

[0011] In a further embodiment of the oil scraper ring, the ring element has two scraper bars: an upper scraper bar on the combustion chamber side and a lower scraper bar on the crankcase side. The recess extends in this case into the area of ​​the upper scraper bar. In this embodiment, the upper scraper ring is circumferentially shorter than the lower scraper ring. This provides a larger ring gap in the upper scraper ring, and as a result, combustion gases can pass through the larger upper gap into the area between the scraper bars and from there into the space behind the oil scraper ring through radially extending oil passages. Here, oil droplets from the area between the scraper bars can be delivered behind the oil scraper ring. As the piston moves downward, the seal of the piston ring becomes less tight, so pressure equalization into the crankcase can occur through the oil drains of the oil scraper piston ring grooves under all operating conditions.

[0012] In a further exemplary embodiment of the oil scraper ring, the recess has a shape that is part of a sphere, cylinder, cone, or rectangle. Thus, the recess is bounded by part of a spherical surface, a cylindrical surface, a conical surface, or a rectangular surface.

[0013] In a further exemplary embodiment of the oil scraper ring, the recesses on the contact surfaces are closer to the contact surfaces on the inner side of the ring. In this embodiment, the recesses on the contact surfaces extend in the region where the edge between the contact surface and the upper ring edge extends, and the recesses of this embodiment form a radial passage from the inner side of the ring to the outer side of the ring. Here, blow-by gases can pass directly behind the ring.

[0014] In a further exemplary embodiment of the oil scraper ring, the oil scraper ring is provided with at least one additional radial recess in an area spaced apart from the contact ends, which extends from the outer side of the ring at the upper ring edge in the direction of the inner side of the ring. In this embodiment, this additional recess ends before reaching the inner side of the ring. In a further embodiment, this at least one additional recess extends to the inner side of the ring and forms a radial channel.

[0015] In a further embodiment of the oil scraper ring, at least one additional recess or radial recess and two recesses at the contact portion are uniformly distributed along the circumference of the piston ring, and the two recesses at the contact portion are considered to be one recess divided by the contact portion. Here, the recesses are, for example, 180 relative to each other o , 120 o , 90 o , 60 o or 30 o It is placed at a distance of . For a larger number of recesses, it is distributed accordingly.

[0016] In a further embodiment of the oil scraper ring, it is designed as a two-part oil scraper ring. In this embodiment, the oil scraper ring has a circumferential groove on the inner side of the ring into which at least one expander, such as a hose spring, is inserted.

[0017] According to an additional 3-part embodiment of the oil scraper ring, this effect is ensured by the selection of different "rail" contact plays. In another preferred embodiment, an even number of additional recesses or radial recesses are used. As a result of a circumferential arrangement that is closer or closer to one another, the ring back area remains free from recesses, and as a result, the risk of ring failure at the point of most severe load during ring assembly can be reduced. When using an even number of additional recesses or radial recesses arranged symmetrically with respect to mirror surfaces passing through the ring gap, the ring back remains free from recesses, and the overall stability of the ring is improved.

[0018] According to a further exemplary embodiment of an oil scraper ring, each of the two recesses and at least one radial recess has different heights or depths in the radial direction, wherein the two recesses located immediately at the ring gap have the greatest depth (axially). Each adjacent radial recess has a smaller depth in the axial direction, and finally, the radial recesses located closest to the ring back are designed to be the flattest.

[0019] According to another exemplary embodiment of the oil scraper ring, two recesses or at least one radial recess has a depth of 0.1 to 0.3 mm. In this case, the depth is measured axially.

[0020] According to a further exemplary embodiment of the oil scraper ring, two recesses and / or at least one radial recess are designed so that they do not interrupt the upper scraper ring.

[0021] According to a further embodiment of the present invention, a piston ring set is provided comprising the oil scraper rings of the aforementioned oil scraper rings and further comprising at least one oil control ring (or intermediate piston ring), wherein, preferably, another compression ring may also be provided. The oil control ring comprises a control ring element comprising an upper control ring edge, a lower control ring edge, an inner control ring side located radially inward, and an outer control ring side located radially outward. The control ring element is provided with two control contact ends where the control ring gap is located. The contact ends have opposing control contact surfaces. In the control ring in the region of the control contact ends, two recesses are provided in each case, at least on the outer side of the ring, each of which is adjacent to each contact surface and the upper ring edge. In the piston ring set, two piston rings are provided in the region of each contact portion, wherein the recesses in the contact portion are widened relative to each other in each case.

[0022] The present invention is described below with reference to schematic prior art drawings and exemplary embodiments of the present invention. Brief explanation of the drawing

[0023] Figure 1 shows a partial view of the ring gap area of ​​a conventional oil scraper ring. FIG. 2 is a diagram of a partial view of an oil scraper ring according to the present invention having inclined recesses in the ring gap. FIG. 3 is a partial view of an oil scraper ring according to the present invention having recesses in a ring gap defined by a partial surface of a conical surface. FIG. 4 shows a partial diagram of an oil scraper ring according to the present invention having rectangular recesses in the ring gap. FIG. 5 is a partial view of an oil scraper ring according to the present invention having recesses of a ring gap extending from an outer side to an inner side. FIG. 6 shows a partial view at a point spaced apart from the ring gap, where a radial recess is provided to interrupt the upper scraper bar. Figures 7 and 8 show diagrams of additional versions of the radial recess that are not interrupted by the upper scraper bar in each case. Figure 9 shows a diagram of an additional version of a radial recess extending from the outer side of the ring to the inner side of the ring. Specific details for implementing the invention

[0024] In all of the following drawings and explanatory text, identical or similar reference numbers are used to refer to identical or similar elements and components.

[0025] FIG. 1 shows a partial perspective view of a conventional oil scraper ring (1) in the ring gap (18) region. The conventional oil scraper ring (2) comprises a ring element (6) having an upper ring edge (8), a concealed lower ring edge, and also an invisible inner ring side and outer ring side (14). The ring element (6) is interrupted at a contact portion where two opposing contact surfaces (20) are formed between the ring gap (18). Herein and below, the ring gap dimensions are always considered to be in the installed state. At least one scraper bar (24, 26) is provided on the outer ring side of the ring element (6). Oil scraper rings according to the prior art and / or the present invention may additionally be provided with oil passages extending from the outer ring side toward the inner ring side between the scraper bars, but are not shown for clarity.

[0026] FIG. 2 shows a partial perspective view diagram of an oil scraper ring (4) according to the present invention in a ring gap (18) region having sloping recesses (28). Here, the oil scraper ring (4) according to the present invention also includes a ring element (6). Here, the ring element includes an upper ring edge (8), an invisible lower ring edge, a concealed inner ring side, and an outer ring side (14). The ring element (6) has a ring gap (18) defined by two opposing contact surfaces (20). On the outer ring side (14), the ring element (6) has at least one scraper bar (24, 26). In the region of the contact surfaces (20), the oil scraper ring (4) has two recesses (28), one on each contact surface (20). In this case, each of the recesses is adjacent to the outer side of the ring (14), the respective contact surface (20), and the upper ring edge (8). In FIG. 2, each of the recesses corresponds to a roughly triangular prism. Here, blow-by gases passing through at least two compression rings or oil control rings can flow into an intermediate chamber between the upper scraper bar (24) and the lower scraper bar (26). There, the blow-by gases can flow circumferentially and flow inward through an oil passage not shown toward the base of the oil scraper ring groove to mix in oil droplets. This allows more oil to be fed back toward the crankcase, where less oil can enter the combustion chamber, especially in overrun mode.

[0027] FIG. 3 shows a partial view of an oil scraper ring according to the present invention corresponding to FIG. 3, excluding the shape of the recesses. Instead of recesses having a triangular cross-section, recesses defined by a portion of a conical surface are used here. As a result of this shape, blow-by gases can flow much better in the direction of the intermediate space between the upper scraper bar (24) and the lower scraper bar (26).

[0028] FIG. 4 illustrates additional possibilities for configuring the shape of the recesses (28). Other parts of FIG. 4 correspond to FIG. 2 and FIG. 3. The recesses (28) of FIG. 4 are bounded by rectangular surfaces.

[0029] FIG. 5 illustrates an additional possible embodiment of the ring gap (18) or recesses (28). As in FIG. 4, the recesses (28) of FIG. 5 are bounded by rectangular surfaces, where the recesses extend radially through the oil scraper ring (4). Here, too, blow-by gases can flow directly through the recesses (24, 26) toward the ring groove base.

[0030] FIG. 6 shows an example of an oil scraper ring used at a location spaced apart from the ring gap and contact surfaces of FIG. 4. These are designated as radial recesses (34) so ​​as to be distinguishable from the recesses of the ring gap. Here, too, this example is based on the principle of achieving an enhanced flow from the outside to the inside through the oil scraper ring by blow-by gases.

[0031] In FIG. 7, the radial recess (34) of FIG. 6 is designed to be only very flat so that the radial recess (34) does not interrupt the upper scraper bar (24) axially. The radial recess (34) of FIG. 7 extends radially only over a portion of the upper ring edge (8). The radial recess (37) is formed over the entire upper ring edge (8), and thus the radial recess forms only a passage for the piston ring groove base with the positively twisted oil scraper ring. When the oil scraper ring is twisted in the reverse direction, the continuous edge between the inner side of the ring and the upper ring edge comes into contact with the upper oil scraper piston ring groove of the piston, thereby preventing the passage of oil radially.

[0032] In FIG. 8, the radial recess (34) is designed to be very flat as in FIG. 7, and here too, the radial recess (34) does not interrupt the upper scraper bar in the axial direction. In FIG. 8, the radial recess (37) extends across the entire upper ring edge (8), and thus the radial recess forms a passage to the piston ring groove base at each twist position of the oil scraper ring.

[0033] In FIG. 9, the radial recess (34) of FIG. 6 extends to the inner side of the ring. Explanation of the symbols

[0034] 2: Conventional oil scraper ring 4: Oil scraper ring according to the present invention 6: Ring element 8: Upper ring edge 14: Ring outer side 18: Ring gap 20: Contact surface 24: Upper scraper bar 26: Lower scraper bar 28: Recess 30: Width of the ring gap 32: Width of the recess 34: Radial recess 36: Width of the radial recess 38: Piston Ring Set 40: Oil control ring 42: Oil control ring element 44: Upper control ring edge 50: External side of the control ring 52: Control ring contact surface 54: Control ring gap 56: Control ring recess

Claims

Claim 1 An oil scraper ring (4) comprising a ring element (6), wherein the ring element (6) comprises an upper ring edge (8), a lower ring edge, an inner ring side and an outer ring side (14); wherein the ring element (6) is provided with two opposing contact surfaces (20), and a ring gap (18) exists between the contact surfaces (20); wherein the ring element (6) is provided with at least one scraper bar (24, 26) on the outer ring side (14); wherein the oil scraper ring (4) is provided with two recesses (28), each of which is located in the area of ​​the contact surfaces (20), and each of which is adjacent to at least the outer ring side (14), each contact surface (20), and the upper ring edge (8); wherein the oil scraper ring (4) has the ring An oil scraper ring (4) having at least one additional radial recess (34) provided in an area spaced apart from the gap (18), wherein the radial recess (34) extends from the upper ring edge (8) in the direction of the ring outer side (14) in the direction of the ring inner side. Claim 2 In claim 1, the recesses (28) are oil scraper rings (4) that extend symmetrically with respect to the mirror plane of the contact surfaces (20). Claim 3 An oil scraper ring (4), wherein, in the installed state, the width (30) of the ring gap (18) is defined as the distance of the contact surfaces (20) in the circumferential direction, and the width of the sum of the width (32) of the recesses (28) in the circumferential direction and the ring gap (18) in the installed ring is 2 to 5 times greater than the width (30) of the ring gap. Claim 4 An oil scraper ring (4), wherein the ring element (6) comprises two scraper bars, an upper scraper bar (24) and a lower scraper bar (26), and the two recesses (28) extend into the area of ​​the upper scraper bar (28). Claim 5 An oil scraper ring (4) characterized in that, in claim 4, the upper scraper bar (24) is shorter than the lower scraper bar (26) by the width of the recesses (32). Claim 6 An oil scraper ring (4) according to claim 1, wherein each of the two recesses (28) is characterized by being bounded by a part of a spherical surface, a cylindrical surface, a conical surface, or a cuboid surface. Claim 7 An oil scraper ring (4) according to claim 1, wherein the two recesses (28) on the contact surface (20) are further adjacent to the inner side of the ring. Claim 8 An oil scraper ring (4) according to claim 1, characterized in that at least one radial recess (34) extends into the inner side of the ring. Claim 9 An oil scraper ring (4) according to claim 1, wherein the two recesses (28) and the at least one radial recess (34) on the ring gap (18) are uniformly distributed along the circumference of the oil scraper ring (4). Claim 10 An oil scraper ring (4) according to claim 1, characterized in that the at least one radial recess (34) closer to the ring gap (18) and the two recesses (28) are positioned closer to each other at the ring back, and an even number of radial recesses (34) are used. Claim 11 An oil scraper ring (4) according to claim 1, wherein the at least one radial recess (34) closer to the ring gap (18) and the two recesses (28) each have a depth that decreases in the circumferential direction in the direction of the ring back. Claim 12 In claim 1, the two recesses (28) and the at least one radial recess (34) have a depth of 0.1 to 0.3 mm, an oil scraper ring (4). Claim 13 An oil scraper ring (4) according to claim 1, wherein the two recesses (28) and the at least one radial recess (34) do not interrupt the upper scraper ring. Claim 14 delete

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