DE20211694U1 - Piston ring combination for sealing a piston against the cylinder comprises outer piston ring which has a step-shape flat portion which is symmetrical at both sides of the ring cant - Google Patents

Abstract

The outer piston ring (3) has a step-shape flat portion (9) which is symmetrical at both sides of the ring cant (5). The step height of the cylinder wall may be the same, rising or increasing in steps. The inner piston ring (4) has an L-shaped, angled molded body (7) which engages into the flat portion (9) of the outer piston ring. The ring cant is covered sideways, and from the groove depth upto the cylinder wall.

Description

[Utility model application]

[Name of the invention:] Piston ring coxn b i na ti on

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[Description]

The invention relates to a piston ring combination for the gas-tight sealing of a piston against a cylinder.

[State of the art]

US Patent 1699135 discloses a highly sealing cylinder ring that consists of a ring combination of two rings. One outer ring is L-shaped with a vertical and a horizontal ring. The second inner ring fits precisely into the L-shaped ring, so that the ring combination as a whole has a rectangular cross-section. The vertical ring is recessed in the area of the ring joint in such a way that a projection of the inner ring fits into this gap and covers the ring joint.

This piston ring combination has the disadvantage that it is complicated to manufacture to a precise fit. The L-shaped outer main ring has a very weak cross-section and the inner ring, which serves to close the ring joint of the outer ring, has little elasticity. The ring joint of the outer main ring is not completely sealed at the rear, so that gas pressure can build up from below through the gap, which the seal cannot withstand.

[Task of the invention]

The object of the invention is to create a piston ring seal that is easy to manufacture and assemble and provides a high gas seal in both directions of movement of the piston. The part of the piston ring combination that carries the piston ring closure should be highly elastic and prevent the partial rings from twisting against each other and the entire piston ring combination from twisting against the piston.

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The problem is solved with the features of the first protection claim. Advantageous further developments and embodiments are the subject of the subclaims.

The piston ring combination for sealing a piston against a cylinder consists of two rings lying coaxially one inside the other in a piston groove, the ring joints of which are arranged offset, whereby the inner ring has a closure for the ring joint of the outer ring, which also serves as the main ring.

The outer piston ring or main ring is flattened symmetrically and in a stepped manner on both sides at its ring joint, whereby the step height from the cylinder wall towards the piston groove depth is the same, increasing or increasing in steps.

The inner piston ring has an L-shaped, angled molded body that engages the flat on the ring joint of the outer piston ring in such a way that the ring joint is covered laterally and from the groove depth to the cylinder wall. The molded body completely fills the flat on the ring joint of the outer piston ring, except for a small lateral expansion gap. This type of ring joint closure secures both rings against mutual twisting.

In an advantageous embodiment, the shaped body is trapezoidal in its plan view, with the shorter side of the trapezoid facing the cylinder wall.

At the same time, the coaxial arrangement of the inner ring in the outer ring completely covers the ring joint of the outer ring from behind in the groove depth.

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In a further advantageous embodiment, the inner piston ring has a nose at a suitable location that engages in a notch in the piston groove. For example, the nose is located on the molded body.

In this inventive piston ring combination, the outer main ring can be made of a cast iron alloy and the inner ring, which must mainly have a sealing and spring effect, can be made of elastic steel. However, an arrangement made of steel and steel is also conceivable.

A further advantage of this invention is that when using different materials, the expansion coefficients do not in principle have to be taken into account.

In addition, as with a single ring arrangement, it is possible that the entire piston ring combination can be kept low in height.

The high elastic effect of the inner ring is also achieved by its very low wall thickness (approx. 0.6 mm). The closure piece can be kept relatively short (approx. 10 mm). The low contact pressure of the inner ring does not significantly increase the contact pressure of the entire piston ring combination due to its spring tension.

The sealing effect of the piston ring combination can be further improved in both directions (combustion chamber → crankcase and crankcase → combustion chamber) if two piston ring combinations are arranged opposite each other, i.e. the shaped body sealing the ring joint of the outer piston ring points upwards and downwards.

Another advantageous embodiment of the piston ring combination is that the outer ring and the inner ring have a uniformly increasing and decreasing wall thickness over the circumference, offset from each other by 180°, so that the common wall thickness of the piston ring combination

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is the same at every point on the circumference. If, for example, the inner ring tapers off in a knife-like manner at its ring joint, the depth of this ring joint is eliminated.

Finally, it may be advantageous for an interlocking profile (e.g. small grooves) to be arranged on the inner ring and/or the outer ring in order to prevent vertical displacement of the two rings in the piston groove against each other.

The advantages of the piston ring combination according to the invention are:

significantly extended oil change intervals,

a higher average torque (more power),

more even stress on the piston, especially in high-performance engines or diesel engines with small piston diameters,

- smoother running and a later ignition timing or start of delivery,

longer engine mileage with an average lower environmental impact (reduction in emissions, less oil leakage from the crankcase, etc.),

lower fuel consumption,

a particularly good cold start behavior.

[Examples]

Some examples of the piston ring combination are described in more detail using drawings.

Show it:

Fig. la: The two rings of the piston ring combination in a representation loosely on top of each other,

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Fig. Ib: The two rings of the piston ring combination in combination,

Fig. 2: The piston ring combination in a side view and mounted in a piston groove,

Fig. 3: A representation of the piston ring combination in section AA according to Fig. Ib,

Fig. 4: A representation of the piston ring combination, in section BB according to Fig. Ib,

Fig. 5: A design of the piston ring combination with mutually increasing and decreasing wall thickness

ke of the piston rings.

In Figures la and lb, the basic structure of the new piston ring combination with the outer ring 3 and the inner ring 4 is shown in two perspective views without piston 1 and cylinder 2. Fig. la shows the two rings 3, 4 individually one above the other and Fig. lb the rings 3, 4 in combination, as they are installed in a piston groove 8.

The outer ring 3 is the main ring and the inner ring 4 serves as a sealing, spring and locking ring.

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[List of reference symbols]

Piston 1

Cylinder 2

Outer piston ring, main ring 3

Inner piston ring 4

Ring joint outer ring 5

Ring joint inner ring 6 Form body, ring joint closure 7

Piston groove 8

Piston groove depth 8a

Flattening at the ring joint 9

Nose Notch Piston Groove Profile

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Claims (7)

1. Piston ring combination for sealing a piston ( 1 ) against a cylinder ( 2 ) with a closure of the ring joint ( 5 , 6 ) by two rings ( 3 , 4 ) lying one inside the other in the piston groove ( 8 ), the ring joints ( 5 , 6 ) of which are arranged offset, characterized in that - the outer piston ring ( 3 ) has a symmetrical and stepped flattening ( 9 ) on both sides at the ring joint ( 5 ), the step height from the cylinder wall ( 2 ) in the direction of the piston groove depth ( 8 a) being equal, increasing or increasing in steps, - the inner piston ring ( 4 ) has an L-shaped angled shaped body ( 7 ) which engages in the flattened portion ( 9 ) on the ring joint ( 5 ) of the outer piston ring ( 3 ) in such a way that the ring joint ( 5 ) is covered laterally and from the groove depth ( 8 a) to the cylinder wall ( 2 ). 2. Piston ring combination according to claim 1, characterized in that the shaped body ( 7 ) is trapezoidal in shape, the shorter side of the trapezoid facing the cylinder wall ( 2 ). 3. Piston ring combination according to claim 1, characterized in that the shaped body ( 7 ) is rectangular. 4. Piston ring combination according to claim 1, characterized in that a nose ( 10 ) for engagement in a notch ( 11 ) in the piston groove ( 8 ) is arranged on the inner piston ring ( 4 ). 5. Piston ring combination according to claim 5, characterized in that the nose ( 10 ) is arranged on the shaped body ( 7 ). 6. Piston ring combination according to claim 1, characterized in that the outer ring ( 3 ) and the inner ring ( 4 ) have a uniformly increasing and decreasing wall thickness over their circumference, offset from one another by 180°, so that the common wall thickness of the piston ring combination is the same at every point on the circumference. 7. Piston ring combination according to claim 1, characterized in that an interlocking profile ( 12 ) is arranged between the inner ring ( 4 ) and the outer ring ( 3 ).