EP2898208A1

EP2898208A1 - Insert and internal combustion engine comprising insert

Info

Publication number: EP2898208A1
Application number: EP13736763.7A
Authority: EP
Inventors: Michele Schiliro; Anko Ernst; Ludwig KLÄSER-JENEWEIN
Original assignee: MTU Friedrichshafen GmbH
Current assignee: Rolls Royce Solutions GmbH
Priority date: 2012-07-04
Filing date: 2013-06-28
Publication date: 2015-07-29
Also published as: CN104541043A; US10316971B2; US20150144089A1; HK1205225A1; DE102012013379A1; WO2014005687A1

Abstract

Disclosed is an insert (31) that can be positioned in a gap (29) between a first front face (25) of a cylinder liner (3), said face facing a cylinder head (9), and a second front face (27) of the cylinder head (9), said face facing the cylinder liner (3). The insert (31) is characterised in that it comprises at least one compressible material.

Description

Insert and internal combustion engine with insert

The invention relates to an insert according to the preamble of claim 1 and an internal combustion engine according to the preamble of claim 9.

Inserts and internal combustion engines of the type discussed here are known. Such an internal combustion engine comprises at least one cylinder, the one

Cylinder liner comprises, in addition to the cylinder on a one - in the cylinder liner seen in the axial direction of the cylinder liner displaceably arranged in the cylinder liner arranged opposite side cylinder head having a first end face of the cylinder liner facing the second end face. The cylinder liner is held in the internal combustion engine by being displaced from the cylinder head in the region of a bushing collar against a so-called

Balcony seat of a crankcase is pressed. A frictional connection of the contact forces extends over a radially outwardly arranged region of the bush collar in order to avoid shearing of a radially inner region of the cylinder liner. To absorb the contact forces, a force introduction element is provided in the radially outer region of the cylinder liner, which is typically as copper-plated

Iron ring is formed. About this runs preferably the entire power flow from the cylinder head into the bushing collar of the cylinder liner. To avoid that contact forces also act in the radially inner region of the bushing collar, a distance between the first end face and the second end face is preferably provided, so that an overall annular gap is given, which - seen in the radial direction - to an interior of the Cylinder liner is open. This one as well

Dead space designated gap has a negative effect on a combustion in one

Combustion chamber of the cylinder, because in the dead space unburned residual gas accumulate or an undefined mixture state of air, fuel gas and Incomplete combustion products. In particular, it is possible that a pressure wave, which results from combustion in the combustion chamber, ignites residual gas in the dead space, which results in knocking combustion. Furthermore, it is possible that lubricant, in particular oil, collects in the dead space, which leads to formation of soot and to the accumulation of hot spots, which in turn can reach the combustion chamber in an undefined manner, where they can lead to uncontrolled ignitions or knocking. The proportion of unburned hydrocarbons is increased by quenching in the gap, which leads to increased hydrocarbon emission in the exhaust gas of gas engines with homogeneous mixture compression. It is therefore desirable to minimize the dead space as far as possible.

European Patent Application EP 1 918 559 A2 discloses an insert for this purpose, which can be used either as part of a cylinder head gasket or separately from a cylinder head gasket

Cylinder head gasket is formed. To ensure that a power flow runs only in a radially outer region of the cylinder liner, the range of the

Dead space filling or sealing insert formed weakened and / or formed of a softer material compared to an area in which contact forces are introduced. In particular, due to manufacturing tolerances in the series, however, it is not possible in this way to actually seal the dead space in each case gap-free and at the same time to ensure that contact forces are introduced only in the designated radially outer area. Also, the material softer or weakened compared to the material provided in the force introduction region still has a hardness which makes it necessary to provide an at least slight gap for tolerance adjustment if any influence on the force distribution is to be avoided. The dead space is indeed reduced in this way, but not effectively closed.

The invention is therefore based on the object, an insert and a

To provide internal combustion engine, with which or in which the dead space can be efficiently sealed, while ensuring at the same time in each case that the power flow for attachment of the cylinder liner extends exclusively in the space provided radially outer area.

The object is achieved by an insert with the features of claim 1 is created. This is characterized by the fact that they at least one Compressible material includes. As a result, the insert can be compressed to an actual axial gap, ie an axial distance between the first and the second end face, without substantial force, whereby the dead space is efficiently sealed and at the same time any influence on the force flow in the radially outer region of the sleeve is avoided ,

An insert is preferred, which is characterized in that the at least one compressible material is selected so that a force that is necessary for deformation of the insert to a minimum expected axial gap of the dead space in the series is small compared to a static force acting in the mounting portion of the cylinder liner on the force introduction element. It is not absolutely necessary that a separate force introduction element is provided. Also, the collar of the cylinder liner itself may be provided as a force introduction element, or a cylinder head gasket may act as a force introduction element. The insert is preferably compressible to about half of its axial height, for which purpose only a force is needed which is negligible compared to the force acting in the attachment portion. Accordingly, the power flow for attachment of the cylinder liner through the liner is not or at least not significantly changed. This can be flexibly adapted to an axial clearance dimension actually present with respect to the manufacturing tolerances without substantially changing the power flow, wherein at the same time the dead space is efficiently sealed or closed or filled in relation to the combustion chamber.

It is preferred a deposit, which is characterized in that the force for the deformation thereof to a minimum expected axial gap of the

Dead space is necessary, from at least 4 to a maximum of 8 kN. The force is preferably from at least 5 to at most 7 kN, preferably 6 kN, particularly preferably 6.4 kN. Alternatively, in particular if the insert comprises a different material, the force is preferably from at least 0.5 to at most 2 kN, preferably from at least 1 to at most 1.5 kN, particularly preferably 1.4 kN. At the here

in any case, it is ensured that these values for the compression forces acting on the insert are substantially smaller and negligible in comparison with the static forces acting in the attachment section of the insert

Cylinder liner act. Accordingly, a force flow existing there is not or at least not significantly, at most so in a negligible way, changed by arranging the deposit in the dead space.

A liner is preferred, which is characterized in that the at least one compressible material comprises a material selected from a group consisting of a ceramic fiber felt, a ceramic fiber cloth, a

Ceramic fiber mat, a ceramic fiber fleece, a metal, in particular a

Metal alloy and a graphite foil. It is possible to combine the materials mentioned with each other or with other suitable materials. Preferably, however, the insert consists of one of the materials mentioned. Particularly preferably, a material is selected for the insert, which is compressible due to its structure. This is especially the case when a fiber material is selected, which is preferably formed as a fabric, scrim, knitted fabric, knitted fabric, felt, non-woven, or mat. Due to the intermediate spaces between the fibers, the material is compressible. An insert comprising a metal and / or a metal alloy is preferably designed to be compressible due to its shape. In particular, one

Cross-sectional shape of the insert is then preferably chosen so that a

Compressibility of the insert - seen in the axial direction - results. If the insert comprises a graphite foil, this is preferably designed to be compressible on account of its material structure. It is possible to combine a compressibility due to a geometry of the insert with a compressibility caused by the material structure,

especially if the insert comprises more than one material.

An insert is preferred, which is characterized in that it consists of the at least one compressible material. Preferably, it is then provided that the insert is formed quasi homogeneous from a single compressible material, wherein preferably one of the aforementioned materials is selected for the insert.

It is also possible for the insert to comprise a carrier material, wherein the at least one compressible material is provided on at least one axial end face of the carrier material on one or both sides. As a carrier material, a metallic sheet is preferably provided. It is also possible that the at least one

Compressible material between two - viewed in the axial direction - oppositely arranged support elements, quasi in sandwich construction, is arranged. There are the support elements preferably formed annular and preferably arranged concentrically to each other.

In one embodiment, in which the insert comprises a carrier material and the at least one compressible material, it is possible that the carrier material is made compressible due to its geometric shape, while the at least one compressible material is compressible due to its material structure. This results in quasi a double compressibility with quasi - seen in the direction of force - arranged in series spring elements.

It is also possible that the carrier material is formed incompressible, wherein the compressibility of the insert is based exclusively on the at least one compressible material. Finally, it is also possible that both the carrier material and the at least one compressible material due to a corresponding

geometric shape are designed compressible. An embodiment in which the carrier material is formed incompressible, has the advantage that the insert as a whole is comparatively stiff and therefore easier to handle than when both the carrier material and the at least one compressible material are formed compressible.

The term "compressible" in connection with an embodiment of the insert which is compressible solely on account of its geometrical shape, does not mean that the material of the insert as such is compressible in the sense of a substance property. Rather, it is merely mentioned here that the insert as such is affected by the geometric Form of their material - viewed in the axial direction - compressible, or deformable.

An insert is preferred, which is characterized in that the at least one compressible material has a honeycomb structure. This is preferably the case when the insert comprises a graphite foil. The honeycomb structure causes a

Compressibility of the material, wherein the honeycomb are preferably arranged so that forces that cause a compression of the insert, are introduced substantially perpendicular to walls of the individual honeycomb, but in any case not parallel to the walls. So it is possible that the honeycomb walls due to the

Compression forces are pivoted or dodge, causing the Total material is compressed or compressed. It is obvious that the material of the insert would be much stiffer or less compressible if the honeycombs were oriented so that the forces were introduced parallel to the walls of the honeycombs. It is not necessarily provided that the individual honeycombs have a hexagonal shape, but in a preferred embodiment this is possible. If the honeycombs have a hexagonal structure, they are preferably arranged, according to what has been explained above, in such a way that a sixfold

Symmetryeachse of the honeycomb is oriented perpendicular to the force introduction direction. In this case results - as already described - a particularly good compressibility. Honeycombs which have a different shape or symmetry are preferably oriented accordingly.

It is also a deposit preferred, which is characterized in that they have a

Half bead includes. This is particularly preferred when the deposit a

Metal alloy comprises or consists of a metal alloy. It is then preferably designed as a bead ring, in particular as an annular insert with half bead, wherein the compressibility or compressibility or deformability of the insert is ensured by the semi-bead shape.

It is also a deposit preferred, which is characterized in that it is geometrically tuned to the cylinder liner so that it extends in the mounted state - seen in the radial direction - up to a combustion chamber boundary. In this case, the insert fills the dead space - in the radial direction - at least towards the combustion chamber boundary and seals it against the combustion chamber. Due to the compression of the insert this fills the dead space - seen in the axial direction - from. It is therefore

excluded that residual gas enters the dead space or an undefined

Mixture state arises in the same.

It is also preferred an embodiment in which the insert is formed and adapted to the cylinder liner and the cylinder head so that it completely fills the dead space in the assembled state, preferably it ends at the combustion chamber boundary, thus does not protrude beyond this into the combustion chamber ,

It is also a deposit preferred, which is characterized by the fact that in the

Is formed substantially annular. So it has an outer and a inner diameter, which are geometrically matched to the dead space. In particular, it is preferably provided that the inner diameter of the insert is matched to an inner diameter of the cylinder liner, that the insert does not protrude into the combustion chamber of the cylinder - seen in the radial direction.

Preferably, the inner diameter of the insert is selected equal to the inner diameter of the cylinder liner, so that the insert extends to the combustion chamber boundary and seals and fills the dead space. It is possible that the

Cylinder liner has a chamfer, in the area of their inner diameter - seen in the axial direction - increases towards the deposit. The inner diameter of the insert is selected in this case preferably equal to the immediately adjacent to the insert inner diameter of the cylinder liner.

The object is also achieved by providing an internal combustion engine having the features of claim 9. This is characterized by the fact that, at least in regions, an insert according to one of the embodiments described above is arranged between the first and the second end face, also referred to as dead space. This results in the advantages already described in connection with the insert.

Preferably, the insert extends - seen in the radial direction - up to a

Combustion chamber boundary of the internal combustion engine. As a result, it seals the dead space with respect to the combustion chamber. Particularly preferably, the insert fills the dead space completely, wherein it preferably ends at the combustion chamber boundary, so not beyond this - in the radial direction - protrudes into the combustion chamber.

Finally, an internal combustion engine is preferred, which is characterized in that the insert is formed as a separate component. It is then in particular as

annular element, independent of a coke-scraper ring, the

Cylinder liner, the cylinder head, a cylinder head gasket and / or the

Force introduction element provided. Alternatively, it is preferred that the insert be part of a coke scraper ring, the cylinder liner, the cylinder head, a

Cylinder head gasket and / or the force introduction element is formed.

In particular, the insert, especially the at least one, is compressible

Material of the insert molded to the other component, glued, welded, sintered, cast, forged, or in another suitable manner to this attached. It is therefore preferably an assembly of the further element and the insert provided.

A particularly favorable configuration results when the insert is provided as part of the liner itself. This is possible in particular in one

Connection area between the cylinder liner and the liner one

high-temperature-stable adhesive connection is provided.

The invention will be explained in more detail below with reference to the drawing. Showing:

Fig. 1 is a detail view of a cylinder of an internal combustion engine in

Longitudinal section, and

Fig. 2 is a detail view of an insert in longitudinal section.

FIG. 1 shows a detailed view of a cylinder 1 of an internal combustion engine in FIG

Longitudinal section. The cylinder 1 comprises a cylinder liner 3, which is supported with a bushing collar 5 in the region of a support surface 7 on a so-called balcony seat of a cylinder crankcase, not shown here - viewed in the axial direction.

With an axial direction here is generally a direction parallel to a

Symmetry axis of the cylinder 1 and the cylinder liner. 3

addressed, so at the same time a direction in which displaced in the cylinder liner 3 displaceably displaced piston during operation of the internal combustion engine. With a circumferential direction, a direction is addressed, which is oriented along a circumferential line about the axial direction. With a radial direction, a direction is addressed, which is perpendicular to the axial direction.

On a side facing a displaceable in the cylinder liner 3 arranged piston - viewed in the axial direction - opposite, the cylinder 1 is closed by a cylinder head 9. Of the cylinder head 9, an inner wall 11 of the cylinder liner 3 and the piston, a combustion chamber 13 is limited, in which one ultimately the

Combustion engine driving combustion takes place.

The cylinder liner 3 is mounted in the internal combustion engine by being pressed axially with the abutment surface 7 against the balcony seat of the crankcase. For this static holding forces are introduced from the cylinder head 9 in a fastening portion 15 in a force introduction element 17. These static holding forces are shown in FIG. 1 by three arrows marked P.

In order to ensure that - viewed in the radial direction - inner region of the cylinder liner 3, which is not supported on the balcony seat, not by the

Holding forces is sheared off, the attachment portion 15 is targeted in a - viewed in the radial direction - outer region of the bushing collar 5 is arranged. In the illustrated embodiment, for this purpose, the cylinder head 9 has a preferably annular projection 19 which rests on the force introduction element 17. Conversely, the bushing collar 5 a - preferably also

annular formed - projection 21, which particularly preferably the

Projection 19 of the cylinder head 9 - viewed in the axial direction - is arranged opposite, so that the static holding forces defined by the projection 19 via the force introduction element 17 are introduced into the projection 21.

It is not absolutely necessary that the force introduction element 17 is provided as a separate element. It is just as possible that that

Force introduction element 17 is formed as a region of the bushing collar 5, wherein then preferably the projection 19 and the projection 21 abut each other directly.

In the illustrated embodiment, however, is a separate

Force introduction element 17 provided that is formed here as a copper-plated iron ring 23. This also acts as a cylinder head gasket. In another embodiment, it is possible that a separate cylinder head gasket is provided alternatively or in addition to the force introduction element 17, or that the cylinder head gasket acts as a force introduction element 17.

Radially within the projections 19, 21 is between a first end face 25 of the cylinder liner and a second end face 27 of the cylinder head 9 a

Interspace formed, which is also referred to as dead space 29. This ensures that the static holding forces exclusively in the

Attachment section 15 act. Due to manufacturing tolerances varies - measured in the axial direction - height of the dead space 29 in series production between 0.2 mm and 0.4 mm. Overall, the dead space 29 has a negative effect on one Combustion in the cylinder 1 by there is a mixture undefined

Composition or by unburned there

Hydrocarbons and their intermediates can attach. This creates potential knocking nests in the dead space 29.

Therefore, it is preferable to arrange an insert, not shown here, in the dead space 29 in order to seal or eliminate it, the insert being particularly preferably provided in an area indicated here by the double arrow P '.

In this case, the insert is preferably annular and corresponds in geometry to the dead space 29 and the area indicated by the double arrow P 'area. In particular, it is preferably provided that the insert does not protrude into the combustion chamber 13, as viewed in the radial direction. However, it extends preferably - seen in the radial direction - up to a through the

Inner wall 11 defined combustion chamber boundary.

The insert comprises a compressible material and is designed such that it reliably seals the dead space 29 independently of the manufacturing tolerances present in a specific exemplary embodiment of the internal combustion engine or of the cylinder 1. Accordingly, it preferably has a height measured in the axial direction which corresponds to at least one largest expected axial distance between the first end face 25 and the second end face 27. This height is therefore preferably 0.4 mm in the present embodiment.

At the same time, the material is preferably selected such that it is compressible again, except in the axial direction, to a smallest expected distance between the first end face 25 and the second end face 27, that is to say to a smallest gap dimension of the dead space 29 In this case, forces occur that would not be negligible compared to the static holding forces acting in the fastening section 15. In the illustrated embodiment, this lower dimension is about 0.2 mm. Accordingly, here the compressible material is preferably chosen so that it is compressible by about half its height present in the unloaded state, wherein the force required for this purpose is small or

is negligible compared to the forces acting in the attachment portion 15 static forces. Overall, it is ensured that the dead space 29 is sealed tight regardless of the actual manufacturing tolerances, at the same time the exclusive force flow through the mounting portion 15 is not disturbed, because the forces acting in the insert compression forces in any case small, especially negligible compared to the static Holding forces in the attachment area 15 are. Accordingly, no gap remains in the area of the dead space 29 in order to ensure the corresponding power flow. Conversely, despite efficient sealing of the dead space 29, there is no danger that one will not be on the balcony seat

supported region of the cylinder liner 3 is sheared off.

Figure 2 shows a detailed view of an embodiment of a liner 31 in longitudinal section. The illustrated embodiment of the insert 31 is made of a

Metal alloy formed and has a - seen in longitudinal section - cranked area or a half bead 33 through which the insert 31 receives its compressibility. It is shown here in unloaded condition, wherein a height h measured in the axial direction is approximately equal to a maximum expected axial clearance of the

Dead space 29 corresponds, preferably slightly larger, so that the insert 31 effectively seals the dead space 29 even at maximum expected gap. Preferably, the height h is about 0.4 mm. The insert 31 is compressible to a height h of about 0.2 mm, without causing forces that occur in the

Compared to the static holding forces acting in the attachment section 15 would not be negligible.

In the illustrated embodiment, the insert 31 are for their

Compressing forces preferably from at least 4 to at most 8 kN, preferably from at least 5 to at most 7 kN, preferably 6 kN, more preferably 6.4 kN. In another embodiment, in which the insert 31 is formed as a graphite foil with honeycomb structure, the corresponding forces are preferably from at least 0.5 to a maximum of 2 kN, preferably from at least 1 to at most 1, 5 kN, more preferably 1, 4 kN.

The insert 31 is preferably formed annularly, with a here

Outer diameter d _a and an inner diameter d. In the embodiment of the insert 31 shown in FIG. 2, which is for use in the embodiment shown in FIG illustrated embodiment of the cylinder 1 is formed, which is

Outer diameter d _a preferably 188.5 mm, wherein the inner diameter d, preferably 172 mm.

It is possible that the insert 31 is formed as an O-ring or a C-ring. Other shapes for the insert 31 are possible. Depending on the shape and / or design of the insert 31, it is possible for the first end face 25 to be processed correspondingly for the abutment of the insert 31.

The following is also apparent: Due to the insert 31 arranged in the dead space 29, a combustion pressure prevailing in the combustion chamber 13 can not effectively propagate in the dead space 29. This effectively prevents a dynamic additional force periodically in the combustion cycle of the cylinder 1 on the

Attachment section 15 and in particular also acts on the balcony seat. In any case, the additional dynamic force which occurs periodically during combustion is clearly minimized by the insert 31. This increases a fatigue strength of

Cylinder liner 3 and in particular also the cylinder. 1

Overall, it can be seen that with the help of the insert 31, a dead space 29 can be minimized, preferably even eliminated, while at the same time a force flow in the

Fixing portion 15 is not changed.

Claims

claims

Insert (31) for arrangement in a dead space (29) between a cylinder head (9) facing the first end face (25) of a cylinder liner (3) and one of the cylinder liner (3) facing the second end face (27) of the cylinder head (9), characterized in that the insert (31) comprises at least one compressible material.

Insert (31) according to claim 1, characterized in that the at least one compressible material is selected such that a force which is for deformation of the insert - seen in the axial direction of the cylinder liner - to a smallest expected axial gap of the dead space (29) is necessary, is small compared to a static force in a mounting section (15) of the

Cylinder liner (3) acts on a force introduction element (17).

Insert according to claim 2, characterized in that the force of at least 4 to at most 8 kN, preferably from at least 5 to at most 7 kN, preferably 6 kN, more preferably 6.4 kN, or from at least 0.5 to at most 2 kN, preferably from at least 1 to at most 1.5 kN, particularly preferably 1.4 kN.

Insert (31) according to one of the preceding claims, characterized

characterized in that the at least one compressible material

Ceramic fiber felt, a ceramic fiber fabric, a ceramic fiber mat, a

Ceramic fiber fleece, a metal, in particular a metal alloy, and / or comprises a graphite foil, preferably consists of one of said materials.

5. insert (31) according to any one of the preceding claims, characterized

in that the insert (31) consists of the at least one compressible material, or in that the insert (31) comprises a carrier material, preferably at least one metallic plate, wherein the at least one compressible material is affixed on one or both sides to axial end surfaces of the

Support material is provided, or wherein the at least one compressible material is arranged between two preferably annularly shaped and preferably concentrically arranged opposite carrier elements.

6. insert (31) according to any one of the preceding claims, characterized

characterized in that the at least one compressible material a

Honeycomb structure has.

7. insert (31) according to any one of the preceding claims, characterized

characterized in that the insert comprises a half bead (33).

8. insert (31) according to any one of the preceding claims, characterized

characterized in that the insert (31) is substantially circular

is trained.

9. internal combustion engine having at least one cylinder (1), wherein the at least one cylinder (1) comprises a cylinder liner (3), and with a cylinder head (9), one of a first end face (25) of the cylinder liner (3) facing the second end face (27), wherein a force introduction element (17) is provided in the region of a static holding force of the cylinder head (9) in the

Cylinder liner (3) is initiated, characterized in that at least partially in a space (29) between the first and the second end face (25,27) is arranged an insert (31) according to one of claims 1 to 8.

10. Internal combustion engine according to claim 9, characterized in that the insert (31) as a separate component or as part of a coke-scraper ring, the

Cylinder liner (3), the cylinder head (9), a cylinder head gasket and / or the force introduction element (17) is formed.