Cylinder Housing With Dry Cylinder Liners

Abstract

A cylinder housing with dry cylinder liners, in particular for internal combustion engines in which the outer surfaces of the cylinder liners taper conically and the cylinder bores also preferably taper conically.

Parent Case Text

This is a continuation of application Ser. No. 22,838 filed Mar. 26, 1970, now abandoned.

Description

The present invention relates to a cylinder housing with dry cylinder liners especially for internal combustion engines. Such types of liners are normally oversize prior to the installation into the cylinder bore with respect to the latter. Consequently, for pressing-in the cylinder liners, very high forces of the order of several thousand Kiloponds have to be applied. This leads to stresses in the installed cylinder liners which seek to equalize themselves during the operation. The consequences thereof are ovalization and warping of the cylinder liners and of the cylinder bores. This makes necessary repeated after-finishing operations. Further form-changes lead to the formation of gaps and hollow spaces between the cylinder bore and the cylinder liner. In internal combustion engines hot gases penetrate from the combustion space into these hollow spaces and attack the surfaces thereof. A further disadvantage are the large forces which have to be applied during the disassembly of the cylinder liners. In addition to the outer surface of the cylinder liners, also the cylinder bores may be considerably damaged by the strong friction connected therewith.

It is the aim of the present invention to eliminate the aforementioned disadvantages and to create a cylinder liner which can be easily assembled and disassembled in and from the cylinder bores of the cylinder housing. This is realized in that the outer surface of the cylinder liner tapers or converges in a conical shape. The cylinder liner can be easily installed in this manner into the cylinder bore. A special chamfering at the upper edge of the cylinder bore may be dispensed with by such arrangement. After the cylinder liner is far-reachingly immersed into the cylinder bore during the insertion into the same and abuts at the upper edge thereof, only a relatively small force application is necessary in order to bring the cylinder liner into its end position. A press is not necessary therefor. Under certain circumstances, already a single hammer blow on an emplaced intermediate plate suffices in order to drive the cylinder liner into its end position within the cylinder bore. Stresses and subsequent deformations of the cylinder liner resulting therefrom are avoided by the slight pressing-in force or pressure. The further significant advantage results therefrom that the cylinder liners can be finish-machined already prior to installation so that after-finishing operations may be dispensed with.

A good abutment of the cylinder liner in the cylinder bore with sufficient adhesion and favorable heat transfer is achieved according to the present invention in that also the cylinder bore tapers or converges in a conical shape. As a result of this measure, the cylinder liner additionally centers itself automatically during the introduction into the cylinder bore so that any canting is precluded.

According to the present invention, the angle of inclination of the outer surface of the cylinder liner is larger than the angle of inclination of the housing bore. As a result thereof, the abutment pressure of the cylinder liner is largest at the hottest and most heavily stressed place within the area of the outer wall of the cylinder housing. The construction of the cylinder liner in accordance with the present invention obviates the need for a collar. Stress peaks which occur as a result of the cross-sectional changes at the transition to the collar are eliminated. The machining time and therewith the price of the cylinder liners are reduced. The grinding-off of the projecting end surface frequently necessary with collar-bushes may be eliminated with the cylinder liner according to the present invention as the latter can be pressed-in so far without difficulty until it is flush with the surface of the cylinder housing.

According to the present invention, the outer surface of the cylinder liner and/or the cylinder bore may be provided with a soft metal layer, for example, made from tin. Small surface inaccuracies are compensated thereby and the heat transfer between cylinder liner and cylinder bore is considerably improved. In contradistinction to the bushes with a cylindrical outer surface in which such a layer is destroyed during the pressing-in operation and is stripped off for the most part, this layer remains preserved with the cylinder liner in accordance with the present invention adapted to be inserted easily.

Accordingly, it is an object of the present invention to provide a cylinder housing with dry cylinder liners which obviates the disadvantages and drawbacks encountered in the prior art.

Another object of the present invention resides in a cylinder housing with dry cylinder liners which eliminates the need for large forces to assemble and disassemble the cylinder liners in and from the cylinder bores.

A further object of the present invention resides in a cylinder housing with dry cylinder liners which practically completely eliminates the danger of wear, ovalization and warping of the cylinder liners and/or cylinder bores.

Still another object of the present invention resides in a cylinder housing with dry cylinder liners which not only greatly reduces the amount of machining operations necessary but also reduces the price for the manufacture and assembly thereof.

A further object of the present invention resides in a cylinder housing with dry cylinder liners which eliminates special forms for the liner and/or the cylinder bore, which avoids stresses and which improves the heat transfer.

These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein:

The single figure is a cross-sectional view through a cylinder housing of a piston internal combustion engine with a dry cylinder liner in accordance with the present invention.

Referring now to the single figure of the drawing, reference numeral 1 designates therein the cylinder bore of a cylinder housing 2 into which is inserted a dry cylinder liner 3. The flangeless end face 4 of the cylinder liner 3 is disposed in one and the same plane with the outer wall 5 of the cylinder housing 2. The outer surface 6 of the cylinder liner 3 tapers conically in the inward direction from the end face 4 thereof. The angle of inclination .alpha. of the outer surface 6 amounts to about 25 minutes. The cylinder bore 1 also tapers conically in the inward direction. The angle of inclination .alpha. of the outer surface 6 of the cylinder liner 3 is about 4 minutes larger than the angle of inclination .beta. of the cylinder bore 1. Preferred dimensions for the tapering of the outer surface of the cylinder liner 3 lie between a cone of about 1 : 50 to a cone of about 1 : 125. The fine-finished or machined outer surface 6 is provided with a tin coating having a thickness of about five thousandths of a millimeter.

The cylinder liner 3 can be secured rapidly and without costly auxiliary means in the cylinder housing 2. For this purpose, one introduces the cylinder liner 3 into the cylinder bore 1 until it abuts with its outer surface 6 at the upper edge thereof. The cylinder liner 3 therefore immerses almost with its entire length into the cylinder bore 1. As a result of the conical construction of the cylinder bore 1 and of the cylinder liner 3, the latter centers itself. One places an intermediate plate (not shown) on the end face 4 of the cylinder liner 3 which projects, for example, with 1/10 of its length, and one is able to press-in the cylinder liner 3 thereafter with a relatively small pressure until its end face 4 is flush with the outer wall 5 of the cylinder housing 2. The end face 4 of the cylinder liner 3 may also project by a small amount, for example, by a tenth of a millimeter, beyond the outer wall 5 of the cylinder housing 2. These differences in height may be compensated for in the assembled internal combustion engines by the seal inserted between the cylinder housing 2 and the cylinder head.

The cylinder liner 3 is securely seated in the cylinder housing 2 after the pressing-in operation. Its outer surface 6 abuts over the entire length or nearly over the entire length thereof in the cylinder bore 1. The abutment pressure is thereby largest in the most strongly loaded zone within the area of the outer wall 6 of the cylinder housing 2 and decreases from there uniformly in the inward direction. The soft tin layer at the outer surface 6 of the cylinder liner 3 equalizes any still existing, local form-deviations and improves the heat transfer from the cylinder liner 3 to the cylinder housing 2. Instead of tin, any other soft metal, for example, aluminum or copper may also be applied onto the outer surface of the cylinder liner 3.

The cylinder liner 3 becomes disengaged readily from the cylinder bore 1 after overcoming an initial resistance and can be pulled out of the cylinder housing 2 simply and without damage to the outer surface 6 or to the cylinder bore 1.

While I have shown and described only one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art, and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

Claims

I claim:

1. An arrangement for an internal combustion engine comprising: a cylinder housing having a bore delimited by inwardly facing bore walls, and a cylinder liner having outwardly facing liner wall surfaces, wherein said liner is positioned in said bore, wherein both said bore walls and liner wall surfaces are conically tapered with the angle of inclination of said bore walls with respect to a longitudinally extending central bore axis being different than the angle of inclination of said liner wall surfaces with respect to said bore axis, and wherein said liner is held in position in said bore exclusively by frictional engagement of said bore walls and liner wall surfaces.

2. An arrangement according to claim 1, wherein said angle of inclination of said liner wall surfaces is greater than said angle of inclination of said bore walls.

3. An arrangement according to claim 2, wherein at least one of the liner wall surfaces and bore walls is provided with a thin soft metal layer to compensate for small surface inaccuracies.

4. An arrangement according to claim 3, wherein the angle of inclination of the liner wall surfaces is lodged between a cone of approximately 1:50 and a cone of approximately 1:125.

5. An arrangement according to claim 2, wherein an upper end of said liner has a larger cross-sectional size than an opposite lower end of said liner such that the liner can be inserted from above into said bore.

6. An arrangement according to claim 5, wherein the relative tapers of the liner wall surfaces and bore walls is such that approximately 90 percent of the liner length can be inserted into the bore before initial frictional engagement between the bore walls and the liner wall surfaces takes place.

7. An arrangement according to claim 6, wherein the upper end of the liner is flush with the top of the bore in the assembled condition.

8. An arrangement according to claim 5, wherein the taper of the liner wall surfaces is such that when the liner is completely inserted in the bore, frictional engagement between the liner wall surfaces and the bore walls takes place throughout substantially the entire length of the liner with maximum frictional engagement at the upper end of said liner and housing where maximum thermal stresses are experienced in use on the engine.

9. An arrangement according to claim 8, wherein at least one of the liner wall surfaces and bore walls is provided with a thin soft metal layer to compensate for small surface inaccuracies.

10. An arrangement according to claim 9, wherein said soft metal layer is on said liner wall surfaces, and wherein said layer remains intact with the liner during assembly such that the liner can be removed and replaced with a new liner without further preparation of the bore.

11. An arrangement according to claim 1, wherein the angle of the inclination of the liner wall surfaces is larger than the angle of inclination of the bore walls by approximately 4 minutes.

12. An arrangement according to claim 7, wherein at least one of the liner wall surfaces and bore walls is provided with a thin soft metal layer to compensate for small surface inaccuracies.

13. An arrangement according to claim 7, wherein the angle of inclination of the liner wall surfaces is lodged between a cone of approximately 1 : 50 and a cone of approximately 1 : 125.

14. An arrangement according to claim 1, wherein an upper end of said liner has a larger cross-sectional size than an opposite lower end of said liner such that the liner can be inserted from above into said bore.

15. An arrangement according to claim 14, wherein the taper of the liner wall surfaces is such that when the liner is completely inserted in the bore, frictional engagement between the liner wall surfaces and the bore walls takes place throughout substantially the entire length of the liner with maximum frictional engagement at the upper end of said liner and housing where maximum thermal stresses are experienced in use on the engine.

16. An arrangement according to claim 14, wherein the tapering of the liner wall surfaces lies between a cone of about 1 : 50 and a cone of about 1 : 125.

17. An arrangement according to claim 2, wherein an upper end of said liner has a larger cross-sectional size than an opposite lower end of said liner, and wherein said lower end of said liner is smaller than an upper opening of said bore such that the liner can be inserted from above into the bore.