EP1965068B1 - Air gap insulation on a cylinder socket - Google Patents

Abstract

The internal combustion engine comprises a crankcase. A crankshaft is pivoted in the crankcase, where a connecting rod is hinged on the crankcase. The connecting rod supports a piston, which is moved from a cylindrical head (3) into a fluid cooled, covering cylindrical sleeve between a lower and an upper dead center. A cylinder liner collar (2) has a height, which corresponds to maximum height of an insert ring (8).

Description

The invention relates to a cylinder liner for an internal combustion engine, in particular for a gas engine, with a crankcase in which a crankshaft is rotatably mounted on which at least one connecting rod carrying a piston is articulated, wherein in the cylinder liner, a piston between a lower and a top dead center in an axial direction K is movable, wherein the cylinder liner has a cylinder liner collar through which the cylinder liner is inserted or fixed in a housing of the internal combustion engine, and wherein a cylinder head side recess is provided, in which an insert ring with a height h _{R is} inserted.

The insert ring is usually designed and arranged so that a top, recessed into the piston piston ring groove projects at the TDC position of the piston to the insert ring.

Such a cylinder liner for an internal combustion engine is known from DE 1 900 922 B known. The teaching of this document is concerned with making available a piston-cylinder liner arrangement in which, despite the presence of an enlarged annular space between the piston and cylinder liner, an oil carbon coating which could contact the cylinder inner wall is avoided in precisely this clearance. This is achieved in that the inner wall of the cylinder liner has a diameter-reduced portion at its combustion chamber end. This section is going through one in the Cylinder liner recessed insert ring produced, wherein the insert ring is preferably made of the same material as the cylinder liner and is firmly inserted into the recess.

In the WO 2004/022960 A1 a cylinder liner is described with a Zylinderbüchsenbund having a cylinder head side recess into which an insert ring is inserted. The insert ring is made of a thermally more stable material than the cylinder liner and serves to prevent deposits on the piston. At an upper end face of the insert ring a recess is provided within the outer wall, so that a direct heat flow is prevented by the insert ring to the frontal part of the cylinder liner. The insulating effect is ensured by a thus formed air gap or the use of ceramics.

In the DE 30 38 235 A1 Also, a cylinder liner with a cylinder liner collar and an air gap insulated insert ring is described.

In SU 1390 410 A1 a cylinder liner with a cylinder liner collar and an insert ring is shown. The insert ring is insulated by an insulating ring.

The invention has the object of developing such a cylinder liner in the form that the stability increases in the region of the combustion chamber end of the cylinder liner and sufficient insulation in this area is ensured.

This object is achieved in that the cylinder liner collar has a height h _B , which is between 83% and 95% or 100% of the height h _{R of} the insert ring. As a result, the cylinder liner collar is considerably higher and thus stiffer than is the case in the prior art. Thus, then other strength-enhancing measures, such as in the groove of the cylinder liner, can be dispensed with. Although it is known that high thermal loads occur in this combustion chamber side area of the cylinder liner. this thermal loads has been counteracted in the past by intensive cooling was sought in this area or the cooling was as close as possible to the front end of the cylinder liner zoom out. However, such intensive cooling makes it necessary to make this area of the cylinder liner or the cylinder liner collar filigree, whereby this area of the cylinder liner, for example caused by the gas forces in the cylinder liner, is more susceptible to distortion. This vulnerability is enhanced over the circumference of the cylinder liner by different wall thicknesses of the surrounding crankcase or other intermediate housing. The occurrence of distortion is favored by tight cylinder spacings that occur due to the desire for short-burning internal combustion engines or adjust in further developments of existing internal combustion engines due to bore enlargements. These problems are avoided by the embodiment according to the invention, wherein for the realization of this embodiment, first the knowledge was necessary that in the past, the thermal loads have been placed too much in the foreground.

Between the insert ring and the cylinder liner, an air gap insulation or an insulating ring is provided. In a further development of the invention, at least one depth gap defined air gap with a Gasamtlänge 1 _{L is} provided in the air gap insulation, wherein the ratio of the height h _{R of} the insert ring to the total length 1 _L between 1.1 and 1.9 or between 1.3 and Is 1.7. As a result, the heat dissipation from the insert ring into the cylinder liner is significantly reduced in this area, so that, as a result, this area of the cylinder liner or cylinder liner collar does not have to be cooled so intensively. Within the Zylinderbüchsenbundes are separate cold storage areas or cooling channels no longer necessary and the cylinder liner or the cylinder liner collar can be formed in this area more solid and torsionally rigid. The higher temperatures occurring in the cylinder combustion chamber due to the insulation can be at least partially absorbed by an intensification of the cooling, in particular in the region of the cylinder head and other measures, for example by an adapted coordination of the combustion, so that, for example, with regard to exhaust emissions and fuel consumption Disadvantages arise. The total length l _{L of} the air gap results when using several separate air gaps in the form of several wells as explained below from the sum of the heights h _{v of} the depressions.

In a further embodiment of the invention, it may be advantageous if the air gap is formed as a recessed into the outer circumference of the insert ring recess or as a recessed into the inner circumference of the recess recess. The circumferential recess results from appropriate material withdrawal. Of course, in the context of the invention, combined embodiments, so for example in the outer periphery of the insert ring and the inner circumference of the recess recesses arranged, be provided, it being important to ensure that on the one hand a good insulation effect is achieved, on the other hand, the insert ring sufficiently stable and solid is held in the cylinder liner.

In addition, it may be advantageous if the depression is arranged coaxially with the insert ring. Instead of the coaxial alignment, a decentralized arrangement is also possible such that the depth of the depression varies over the circumference.

It can also be advantageous if two, three or more depressions are provided which are arranged one above the other with respect to the direction of movement K and at a distance a from one another. Thus, the insulating effect is increased and yet ensures the rigidity of the insert ring.

In addition, it may be provided that, with respect to the axial direction of movement K, the recess has a height h _v and before and after the recess, a web is provided which limits the height h _{v of} the recess. About the web or webs of the insert ring is supported in the recess against the cylinder liner collar. This has a direct influence on the rigidity of the insert ring in the radial direction. Furthermore, the path seals the wells against each other.

In this case, it may be advantageous if the ratio of the height h _{v of} the depression to the distance a is between 1 and 7 or between 3 and 6 or 4.5. According to the desired insulating effect on the one hand and the necessary rigidity of the insert ring on the other hand, the above ratio should be selected.

In this context, it may be advantageous if the insert ring has a thickness d _R and the recess has a depth t _v , wherein the ratio of the thickness d _R to the depth t _v between 2 and 15 or between 7 and 13. With the guarantee of an air gap, the heat transfer is significantly reduced. The above ratio can be selected taking into consideration the rigidity of the insert ring on the one hand and the insulating effect on the other hand.

The insulation can by an insulating ring between the insert ring and the Cylinder liner be formed. For this purpose, for example, a ceramic material in question. The advantage of an additional ring is achieved in the additional support achieved by the insert ring in the cylinder liner by omitting the wells. The insert ring lies flat against the insulating ring and is supported against it. The cylinder liner is still further stiffened overall.

The problem is solved by an internal combustion engine with a cylinder liner described above.

Figur 1

eine Schnittdarstellung des brennraumseitigen Endes einer Zylinderbüchse mit in die Zylinderbüchse eingelassener Luftspaltisolierung;

Figur 2

eine Schnittdarstellung des brennraumseitigen Endes einer Zylinderbüchse mit in die Zylinderbüchse eingelassener Luftspaltisolierung mit in den Einsatzring eingelassener Luftspaltisolierung;

Figur 3

eine Schnittdarstellung nach Fig. 1 mit separatem Isolierring;

Figur 4

eine Skizze zur Ermittlung der Gesamtlänge 1_L des Luftspaltes.

Further advantageous embodiments of the invention are described in the drawings, are described in more detail in the illustrated in the drawings embodiments of the invention. Show it:

FIG. 1

a sectional view of the combustion chamber-side end of a cylinder liner with embedded in the cylinder liner air gap insulation;

FIG. 2

a sectional view of the combustion chamber end of a cylinder liner with let into the cylinder liner air gap insulation with embedded in the insert ring air gap insulation;

FIG. 3

a sectional view to Fig. 1 with separate insulating ring;

FIG. 4

a sketch to determine the total length 1 _{L of} the air gap.

Fig. 1 shows a sectional view of the combustion chamber end of a cylinder liner 1 a particular gas-powered internal combustion engine. The cylinder liner 1 has a Zylinderbüchsenbund 2, between a cylinder head 3 and a housing 4, in particular a crankcase of the internal combustion engine, is clamped. To seal the cylinder liner 1 relative to the cylinder head 3, a cylinder head gasket 5 is provided between these components, which is arranged so that no tension of the cylinder liner collar 2 occurs. Between the cylinder liner 1 and the housing 4, a water jacket 6 is arranged, which is charged with cooling water and extends below the Zylinderbüchsenbundes 2.

In the cylinder liner 2, a recess 7 is incorporated on the side facing the cylinder head 3, which extends from the cylinder head end of the cylinder liner 1 into a region below the housing-side end of the cylinder liner collar 2. In this recess 7, an insert ring 8 is inserted, which is preferably made of the same material as the cylinder liner 1, for example, cast iron. The insert ring 8 has on its outer circumference on an air gap insulation, which are embedded in the embodiment in the form of three annular circumferential recesses 9 in the insert ring 8. The insert ring 8 preferably has an inner diameter which is slightly smaller than that of the cylinder liner 1 in the region below the recess 7. This board of the insert ring 8 causes both on the immersed in the insert ring 8 10th Landstill 10.1 piston adhering carbon and the oil adhering to the insert ring 8 is scraped off by an axial movement direction K of the piston 10. The immersion depth of the piston 10 in the insert ring 8 is designed so that an inserted into an upper piston ring groove 11 piston ring 12 at the top dead center (TDC position) of the piston 10 in the cylinder liner 1 just does not come into contact with the insert ring 8.

The thickness of the insert ring 8 is preferably in the range of 10% to 15% of the total thickness of the cylinder liner collar 2 including the thickness of the recess 7. The rings of the insert ring 8 are larger by about 20% than the height of the cylinder liner collar second

The embodiment according to Fig. 2 differs from the according to Fig. 1 in that recesses 9a embedded in the recess 7 of the cylinder liner 1, for example, are screwed.

The depressions 9, 9 a have a depth t _v in both embodiments, wherein the ratio of a thickness d _{R of} the insert ring 8 to the depth t _{v is} at least 5, ie the depth t _v is up to 20% of the thickness d _R of Insert ring 8 on.

The three recesses 9, 9a are arranged at a distance a from each other and separated by two inner webs 14, 14a, wherein the two outer webs 14, 14a form the upper and lower axial end. The ratio of a height h _{v of} the respective recess 9, 9a to the distance a is about 4.

The air gap formed by the recesses 9, 9a has an overall length 1 _L. The total length 1 _L results according to Fig. 4 from a height h _{R of} the insert ring 8 minus the total length of all the webs 14, 14 a, which corresponds to four times the distance a. The ratio of the height h _{R of} the insert ring 8 to the total length 1 _L is 1.33, ie the total length 1 _L is 75% of the height h _{R of} the insert ring. 8

According to embodiment Fig. 3 an additional insulating ring 13 is provided, which is arranged between the insert ring 8 and the cylinder liner collar 2. The insert ring 8 lies fully against the insulating ring 13 at. The insulating ring 13 is fully against the cylinder liner collar 2.

reference numeral

1

cylinder liner

2

Cylinder liner collar

3

cylinder head

4

casing

5

Cylinder head gasket

6

water jacket

7

recess

8th

insert ring

9

Depression, air gap

9a

Depression, air gap

10

piston

10.1

top land

11

piston ring

12

piston ring

13

insulating ring

14

web

14a

web

a

Distance of the recesses

d _R

Thickness of the insert ring

t _v

Depth of depression

h _B

Height of Zylinderbüchsenbundes

h _R

Height of the insert ring

h _v

Height of the recess

K

axial direction of movement of the piston

1 _L

Gasamtlänge of the air gap

Claims (10)

1. A cylinder liner (1) for an internal combustion engine in which a piston (10) can be moved between a bottom dead centre and a top dead centre in an axial direction K and which comprises a cylinder liner collar (2) by means of which said cylinder liner (1) can be fixed in a housing (4) of said internal combustion engine, wherein on the side of the cylinder head a recess (7) is provided in which an insertion ring (8) having a height h_R is inserted, and an air gap insulation is provided between said insertion ring (8) and said cylinder liner (1),
   characterized in that
   said cylinder liner collar (2) has a height h_B ranging between 83 % and 95 % or 100 % of the height h_R of said insertion ring (8).
2. A cylinder liner (1) according to claim 1,
   characterized in that
   the air gap insulation comprises at least one defined air gap (9, 9a) having a total length l_L, wherein the ratio of the height h_R of the insertion ring (8) to said total length l_L ranges between 1.1 and 1.9 or between 1.3 and 1.7.
3. A cylinder liner (1) according to claim 2,
   characterized in that
   the air gap (9, 9a) is designed as a depression (9) which is formed in the outer periphery of the insertion ring (8).
4. A cylinder liner (1) according to claim 2 or 3,
   characterized in that
   the air gap (9, 9a) is designed as a depression (9a) which is formed in the inner periphery of the recess (7).
5. A cylinder liner (1) according to claim 3 or 4,
   characterized in that
   three or more depressions (9, 9a) are provided which are arranged one above the other in the direction of movement K and are spaced from each other by a distance a.
6. A cylinder liner (1) according to claim 3, 4 or 5
   characterized in that
   the depression (9, 9a) has a height h_v, relative to the direction of axial movement K, and before and behind said depression (9, 9a) a ridge (14, 14a) is provided which limits the height h_v of said depression (9, 9a), wherein the insertion ring (8) is supported on the cylinder liner collar (2) via said ridge (14, 14a).
7. A cylinder liner (1) according to claim 5 or 6 in so far as dependent on claim 5,
   characterized in that
   the ratio of the height h_v of the depression (9, 9a) to the distance a ranges between 1 and 7 or between 3 and 6 or 4.5.
8. A cylinder liner (1) according to any one of the preceding claims,
   characterized in that
   the insertion ring (8) has a thickness d_R and the depression (9, 9a) has a depth t_v, wherein the ratio of said thickness d_R to said depth t_v ranges between 3 and 15 or between 7 and 13.
9. A cylinder liner (1) for an internal combustion engine in which a piston (10) can be moved between a bottom dead centre and a top dead centre in an axial direction K and which comprises a cylinder liner collar (2) by means of which said cylinder liner (1) can be fixed in a housing (4) of said internal combustion engine, wherein on the side of the cylinder head a recess (7) is provided in which an insertion ring (8) having a height h_R is inserted, and an additional insulation ring (13) is provided between said insertion ring (8) and said cylinder liner (1),
   characterized in that
   said cylinder liner collar (2) has a height h_B ranging between 83 % and 95 % or 100 % of the height h_R of said insertion ring (8).
10. An internal combustion engine comprising a cylinder liner (1) according to any one of the preceding claims.

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