Insert and internal combustion engine comprising insert

Abstract

An insert that can be positioned in a gap between a first front face of a cylinder liner, the first front face facing a cylinder head, and a second front face of the cylinder head, the second front face facing the cylinder liner. The insert includes at least one compressible material.

Claims

1. An insert for arrangement in a clearance volume between a first, top-most end face of a cylinder liner, the first, top-most end face facing a cylinder head, and a second end face of the cylinder head, the second end face facing the cylinder liner, wherein the insert comprises at least one compressible material; wherein the insert has an outside diameter and an inside diameter; and wherein the outside diameter and the inside diameter are matched geometrically to the clearance volume so that in an installed state the insert does not extend radially beyond a boundary between the combustion chamber and the clearance volume, wherein the insert further comprises a substrate material, the at least one compressible material being provided on an axially end-most surface of the substrate material.

2. The insert as claimed in claim 1, wherein the at least one compressible material has properties so that, as seen in an axial direction of the cylinder liner, a force required to deform the insert to a minimum axial gap dimension, to be expected, of the clearance volume is small in comparison with a static force acting on a force introduction element in a fastening section of the cylinder liner.

3. The insert as claimed in claim 2, wherein the force is from at least 4 to at most 8 kN.

4. The insert as claimed in claim 3, wherein the force is from at least 5 to at most 7 kN.

5. The insert as claimed in claim 4, wherein the force is 6 kN.

6. The insert as claimed in claim 4, wherein the force is 6.4 kN.

7. The insert as claimed in claim 2, wherein the force is from at least 0.5 to at most 2 kN.

8. The insert as claimed in claim 7, wherein the force is from at least 1 to at most 1.5 kN.

9. The insert as claimed in claim 2, wherein the force is 1.4 kN.

10. The insert as claimed in claim 1, wherein the at least one compressible material comprises at least one of: a ceramic fiber felt; a woven ceramic fiber material; a ceramic fiber mat; a nonwoven ceramic fiber material; a metal; a metal alloy; and a graphite film.

11. The insert as claimed in claim 1, wherein the at least one compressible material consists of one of a ceramic fiber felt; a woven ceramic fiber material; a ceramic fiber mat; a nonwoven ceramic fiber material; a metal; a metal alloy; and a graphite film.

12. The insert as claimed in claim 1, wherein the insert consists of the at least one compressible material.

13. The insert as claimed in claim 1, wherein the substrate material is at least one metal sheet.

14. The insert as claimed in claim 1, wherein the at least one compressible material is arranged between two substrate elements that are annular and are arranged concentrically opposite one another.

15. The insert as claimed in claim 1, wherein the at least one compressible material is a honeycomb structure.

16. The insert as claimed in claim 1, wherein the insert comprises a half-bead.

17. The insert as claimed in claim 1, wherein the insert is substantially annular.

18. An internal combustion engine, comprising: at least one cylinder having a top end, wherein the at least one cylinder comprises: a cylinder liner having a first, top-most end face; and a cylinder head that has a second end face facing the first, top-most end face of the cylinder liner; a force introduction element is provided so that a static retention force is introduced by the cylinder head into the cylinder liner in a region of the force introduction element, the force introduction element directly contacting the cylinder head and the cylinder liner; and an insert according to claim 1 is arranged at least in an area in an interspace between the first, top-most end face and the second end face, the insert being a separate part from the force introduction element.

19. The internal combustion engine as claimed in claim 18, wherein the insert is a separate component.

20. The internal combustion engine as claimed in claim 18, wherein the insert is part of at least one of: a coke scraper ring; the cylinder liner; the cylinder head; a cylinder head gasket; and the force introduction element.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention is explained in greater detail below with reference to the drawing, in which:

(2) FIG. 1 shows a detail view of a cylinder of an internal combustion engine in longitudinal section, and

(3) FIG. 2 shows a detail view of an insert in longitudinal section.

DETAILED DESCRIPTION OF THE INVENTION

(4) FIG. 1 shows a detail view of a cylinder 1 of an internal combustion engine in longitudinal section. The cylinder 1 comprises a cylinder liner 3, which is supportedas seen in the axial directionby means of a liner collar 5 in the region of a supporting surface 7 on a balcony seat of a cylinder block (not shown here).

(5) In general terms, an axial direction refers here to a direction parallel to an axis of symmetry of the cylinder 1 or of the cylinder liner 3, that is say at the same time to a direction in which a piston arranged movably in the cylinder liner 3 moves during operation of the internal combustion engine. A circumferential direction refers to a direction which is oriented along a circumferential line around the axial direction. A radial direction refers to a direction which is perpendicular to the axial direction.

(6) On a side whichas seen in the axial directionlies opposite a piston arranged movably in the cylinder liner 3, the cylinder 1 is closed by a cylinder head 9. The cylinder head 9, an inner wall 11 of the cylinder liner 3 and the piston delimit a combustion chamber 13, in which combustion which ultimately drives the internal combustion engine takes place.

(7) The cylinder liner 3 is secured in the internal combustion engine by being pressed axially by means of the contact surface 7 against the balcony seat of the crankcase. For this purpose, static retention forces are introduced into a force introduction element 17 by the cylinder head 9 in a fastening section 15. These static retention forces are indicated in FIG. 1 by 3 arrows denoted by P.

(8) To ensure thatas seen in the radial directionan inner region of the cylinder lining 3 which is not supported on the balcony seat is not sheared off by the retention forces, the fastening section 15 is deliberately arranged in a region of the liner collar 5 which is on the outsideas seen in the radial direction. In the illustrative embodiment shown, the cylinder head 9 has, for this purpose, a projection 19, preferably of annular design, which rests on the force introduction element 17. Conversely, the liner collar 5 has a projection 21preferably likewise of annular designwhich, as a particular preference, is arranged opposite the projection 19 of the cylinder head 9as seen in the axial directionensuring that the static retention forces are introduced in a defined manner from projection 19, via the force introduction element 17, into projection 21.

(9) It is not absolutely essential here that the force introduction element 17 should be provided as a separate element. It is equally possible for the force introduction element 17 to be designed as a region of the liner collar 5, in which case projection 19 and projection 21 then preferably rest directly upon one another.

(10) In the illustrative embodiment shown, however, a separate force introduction element 17 is provided, which is here designed as a copper-plated iron ring 23. This simultaneously acts as a cylinder head gasket. In another illustrative embodiment, it is possible for a separate cylinder head gasket to be provided as an alternative or as an addition to the force introduction element 17, or for the cylinder head gasket to act as a force introduction element 17.

(11) An interspace, also referred to as a clearance volume 29, is formed radially to the inside of the projections 19, 21, between a first end face 25 of the cylinder liner and a second end face 27 of the cylinder head 9. This ensures that the static retention forces act exclusively in the fastening section 15. Owing to manufacturing tolerances, a height of the clearance volume 29measured in the axial directionvaries between 0.2 mm and 0.4 mm in series production. Overall, the clearance volume 29 has a negative effect on combustion in the cylinder 1 since a mixture of undefined composition forms there, or since hydrocarbons that have not burned and the intermediates thereof can settle there. As a result, potential knock zones can form in the clearance volume 29.

(12) An insert (not shown here) is therefore preferably arranged in the clearance volume 29 in order to seal or eliminate it, wherein the insert is particularly preferably provided in a region indicated here by the double arrow P.

(13) In this case, the insert is preferably of annular design and corresponds in its geometry to the clearance volume 29 or the region indicated by the double arrow P. In particular, provision is preferably made to ensure that the insert does not project into the combustion chamber 13as seen in the radial direction. However, it does preferably extendas seen in the radial directionas far as a combustion chamber boundary defined by the inner wall 11.

(14) The insert comprises a compressible material and is designed in such a way that it seals the clearance volume 29 reliably, irrespective of manufacturing tolerances present in a specific illustrative embodiment of the internal combustion engine or of the cylinder 1. Accordingly, it preferably has a heightas measured in the axial directionwhich corresponds at least to a maximum axial spacing to be expected between the first end face 25 and the second end face 27. In the illustrative embodiment under consideration, this height is accordingly preferably 0.4 mm.

(15) At the same time, the material is preferably chosen so thatonce again as seen in the axial directionit can be compressed down to a minimum spacing to be expected between the first end face 25 and the second end face 27, i.e. to a minimum gap dimension to be expected of the clearance volume 29 without the occurrence during this process of forces which would be non-negligible in comparison with the static retention forces acting in the fastening section 15. In the illustrative embodiment shown, this lower dimension is about 0.2 mm. Accordingly, the compressible material is preferably chosen here so that it can be compressed approximately by half its height in the unloaded state, wherein the force required for this purpose is small or negligible in comparison with the static forces acting in the fastening section 15.

(16) Overall, it is ensured in this way that the clearance volume 29 is sealed in a leaktight manner, irrespective of the manufacturing tolerances that are actually present, while, at the same time, the exclusive flow of force via the fastening section 15 is not disrupted because the compression forces acting in the region of the insert are at most small, in particular negligible, in comparison with the static retention forces in the fastening region 15. In the region of the clearance volume 29, there is therefore no gap remaining in order to ensure the corresponding flow of force. Conversely, there is no risk at all, despite efficient sealing of the clearance volume 29, that a region of the cylinder liner 3 which is not supported on the balcony seat will be sheared off.

(17) FIG. 2 shows a detail illustration of an illustrative embodiment of an insert 31 in longitudinal section. The illustrative embodiment of the insert 31 which is shown is formed from a metal alloy andas seen in longitudinal sectionhas a region which is offset or a half-bead 33, which gives the insert 31 its compressibility. It is shown here in the unloaded state, wherein a height hmeasured in the axial directioncorresponds approximately to a maximum axial gap dimension of the clearance volume 29 that is to be expected, preferably being made slightly larger, thus ensuring that the insert 31 efficiently seals the clearance volume 29, even in the case of the maximum gap dimensioned to be expected. The height h is preferably approximately 0.4 mm. The insert 31 can be compressed to a height h of about 0.2 mm without the occurrence of forces which would be non-negligible in comparison with the static retention forces acting in the fastening section 15.

(18) In the illustrative embodiment of the insert 31 shown, the forces required for the compression thereof are preferably from at least 4 to at most 8 kN, preferably from at least 5 to at most 7 kN, preferably 6 kN, particularly preferably 6.4 kN. In another illustrative embodiment, in which the insert 31 is designed as a graphite film with a honeycomb structure, the corresponding forces are 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.

(19) The insert 31 is preferably of annular design, here having an outside diameter d.sub.a and an inside diameter d.sub.i. In the illustrative embodiment of the insert 31 which is shown in FIG. 2, which is designed for use in the illustrative embodiment of the cylinder 1 which is shown in FIG. 1, the outside diameter d.sub.a is preferably 188.5 mm, while the inside diameter d.sub.i is preferably 172 mm.

(20) It is possible for the insert 31 to be designed as an O-ring or as a C-ring. Other shapes for the insert 31 are also possible. Depending on the shape and/or design of the insert 31, it is possible for the first end face 25 to be machined in a manner appropriate for contact with the insert 31.

(21) The following is found: owing to the insert 31 arranged in the clearance volume 29, a combustion pressure prevailing in the combustion chamber 13 cannot propagate effectively into the clearance volume 29. This is an efficient way of preventing a dynamic additional force from acting periodically on the fastening section 15 and especially also on the balcony seat during the combustion stroke of the cylinder 1. At any rate, the additional dynamic force which arises periodically during combustion is significantly minimized by the insert 31. This increases the endurance of the cylinder liner 3 and especially also of the cylinder 1.

(22) Overall, it is found that a clearance volume 29 can be efficiently minimized or preferably even eliminated with the aid of the insert 31, while, at the same time, a flow of force in the fastening section 15 is not altered.