CYLINDER LINER FOR INTERNAL COMBUSTION ENGINE

Abstract

A cylinder liner for an engine block includes a first engine block bonding surface, and a second engine block bonding surface that provides a lower heat transfer coefficient between the cylinder liner and an adjacent engine block material than the first engine block bonding surface. The second engine block bonding surface extends a substantial portion of the axial length of the cylinder liner.

Claims

1. A cylinder liner for an engine block, the liner comprising: a first engine block bonding surface; and a second engine block bonding surface that provides a lower heat transfer coefficient between the cylinder liner and an adjacent engine block material than the first engine block bonding surface, and wherein the second engine block bonding surface extends a substantial portion of the axial length of the cylinder liner.

2. The cylinder liner of claim 1, wherein the first engine block bonding surface extends around a substantial majority of the circumferential periphery of the cylinder liner.

3. The liner of claim 1, wherein the first engine block bonding surface comprises an as-cast rough surface.

4. The liner of claim 3, wherein the as-cast rough surface comprises a spiny-lock surface.

5. The liner of claim 3, wherein the as-cast rough surface comprises a plurality of projections radially extending between about 0.3 to 0.7 millimeters.

6. The liner of claim 1, wherein the second engine block bonding surface comprises a machined surface.

7. The liner of claim 1, wherein the second engine block bonding surface extends across a majority of the axial length of the liner.

8. The liner of claim 1, wherein the first engine block bonding surface is configured to provide a high thermal conductivity between the liner and the engine block and wherein the second engine block bonding surface is configured to provide a lower thermal conductivity such that heat transfer into an inter-bore section of an adjacent engine block material is reduced during operation of an engine incorporating the cylinder liner.

9. The liner of claim 1, wherein the second engine block bonding surface circumferentially extends across an area adjacent to the inter-bore section of the engine block.

10. The liner of claim 9, wherein the first engine block bonding surface extends across the remaining circumferential extent.

11. An engine block comprising: an engine block material defining a plurality of cylinder bores and an inter-bore section between two of the plurality of cylinder bores; and a cylinder liner positioned within one of the cylinder bores, wherein the liner includes a first engine block bonding surface, and a second engine block bonding surface oriented adjacent to the inter-bore section that provides a lower heat transfer coefficient between the cylinder liner and the engine block material than the first engine block bonding surface, wherein the second engine block bonding surface extends a substantial portion of the axial length of the cylinder liner.

12. The engine block of claim 11, wherein the first engine block bonding surface extends around a substantial majority of the circumferential periphery of the cylinder liner.

13. The engine block of claim 11, wherein the first engine block bonding surface comprises an as-cast rough surface.

14. The engine block of claim 13, wherein the as-cast rough surface comprises a spiny-lock surface.

15. The engine block of claim 13, wherein the as-cast rough surface comprises a plurality of projections radially extending between about 0.3 to 0.7 millimeters.

16. The engine block of claim 11, wherein the second engine block bonding surface comprises a machined surface.

17. The engine block of claim 11, wherein the second engine block bonding surface extends across a majority of the axial length of the liner.

18. The engine block of claim 11, wherein the first engine block bonding surface is configured to provide a high thermal conductivity between the liner and the engine block and wherein the second engine block bonding surface is configured to provide a lower thermal conductivity such that heat transfer into an inter-bore section of an adjacent engine block material is reduced during operation of an engine incorporating the cylinder liner.

19. The engine block of claim 11, wherein the second engine block bonding surface circumferentially extends across an area adjacent to the inter-bore section of the engine block.

20. The liner of claim 19, wherein the first engine block bonding surface extends across the remaining circumferential extent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0027] FIG. 1 is an isometric perspective view of an open deck engine block 100;

[0028] FIG. 2 is an isometric perspective view of an inter-bore portion of an engine block 100;

[0029] FIG. 3A illustrates a microscopic cross-sectional view of an interface between an exemplary as-cast rough surface cylinder liner and an engine block;

[0030] FIG. 3B illustrates a microscopic cross-sectional view of an interface between another exemplary as-cast surface cylinder liner and an engine block;

[0031] FIG. 4A is a perspective view of a conventional cylinder liner;

[0032] FIG. 4B is a perspective view of an exemplary cylinder liner in accordance with the present invention;

[0033] FIG. 5A is a perspective view of an engine block incorporating conventional cylinder liners; and

[0034] FIG. 5B is a perspective view of an engine block incorporating exemplary cylinder liners in accordance with the present invention.

DETAILED DESCRIPTION

[0035] FIG. 1 illustrates an isometric perspective view of an open deck engine block 100. The engine block 100 includes a plurality of cylinder bores 102 that are defined by cylinder liners 104 which have been integrated into the engine block 100 during a casting process. In general, these cylinder liners 104 may be positioned into a mold and the molten engine block material, such as, for example, an aluminum alloy, may then be injected into the mold. The molten material then surrounds the cylinder liners as it fills the mold. The material cools to a solid and the liners are firmly bonded to the engine block material. In an exemplary process, the casting process may inject the molten engine block material under a high pressure to ensure intimate contact between the engine block material and the cylinder liner. As explained above, cylinder liners have been developed which include an as-cast exterior rough surface which provides an excellent structural and thermal bond through mechanical locking between the liner and the engine block material.

[0036] The engine block 100 includes a cooling fluid jacket 106 which is exposed to (open to) the deck surface 110 and is, thus, known as an open deck block. The cooling fluid jacket 106 substantially surrounds the cylinder bores and provides fluid communication channels through which cooling fluid may be circulated to remove and manage heat which may be generated during a combustion process during operation of an engine incorporating the engine block 100.

[0037] FIG. 2 is an isometric perspective providing a closer view of an inter-bore portion of the engine block 100 and illustrating a failure. The inter-bore is known as the portion of the engine block which is between cylinder bores. One method of improving the management and removal of heat from the cylinder bores is to provide a fluid communication channel 108 in the inter-bore section to enable a flow of fluid between cooling fluid jacket 106 sections adjacent to the inter-bore. These fluid communication channels 108 may generally be known as a saw cut channel and this description will refer to these channels 108 as a saw cut channel hereafter. While this description refers to a saw cut the method or tools used to create the slot in the inter-bore area of the engine block is not limited to any particular method or tool. FIG. 2 further illustrates a failure in which the cylinder liners 104 both have developed cracks 110. As explained above, these cracks 110 may have been caused by the increased temperatures of the inter-bore engine block material.

[0038] FIGS. 3A and 3B illustrate a microscopic view of interfaces between two exemplary as-cast rough and spiny surface cylinder liners and adjacent engine block material. In both Figures, the engine blocks are on the left and are indicated by reference numbers 300 and 302, respectively, and the cylinder liners are on the right and are indicated by reference numbers 304 and 306, respectively. FIG. 3A illustrates a cylinder liner 304 having an as-cast rough surface with a surface roughness of about 0.3 to 0.7 millimeters. FIG. 3A clearly illustrates the intimacy that results from the use of a cylinder liner having an as-cast rough surface which provides a relatively high coefficient of thermal transfer between the cylinder liner 304 and the engine block 300. FIG. 3B illustrates a cylinder liner 306 having an as-cast rough surface which may also be further characterized as having a spiny surface with a surface roughness of about 0.3 to 0.7 millimeters. Again, FIG. 3B illustrates an intimacy that results from the use of a cylinder liner having an as-cast rough surface which provides a relatively high coefficient of thermal transfer between the cylinder liner 306 and the engine block 302. In both of these exemplary embodiments, the cylinder liners 304 and 306 are made of a gray cast iron and the engine blocks 300 and 302 are made of an aluminum alloy. However, the present invention is not limited to any particular material for either the engine block or cylinder liner.

[0039] FIG. 4A illustrates a conventional cylinder liner 400 having an exterior surface 402 with an as-cast rough surface extending across substantially the entire exterior surface or outside diameter. In contrast, FIG. 4B illustrates an exemplary cylinder liner 404 having a first engine block bonding surface 406 and a second engine block bonding surface 408. The second engine block bonding surface 408 provides a lower heat transfer coefficient between the second engine block bonding surface 408 and an adjacent engine block material (not shown) into which the cylinder liner 404 may be cast than the heat transfer coefficient between the first engine block bonding surface 406 and an adjacent engine block material.

[0040] The second engine block bonding surface 408 extends a substantial portion of the axial length of the cylinder liner. It is to be understood that the second engine block bonding surface is not limited to any particular axial length. The extent of coverage of the second engine block bonding over the exterior surface of the cylinder liner only needs to be sufficient to reduce the thermal transfer coefficient from the cylinder bore into an inter-bore section of an engine block without limitation.

[0041] When the cylinder liner 404 is cast into an engine block, the second engine block bonding surface 408 may be oriented to be adjacent to an inter-bore section of the engine block such that the coefficient of thermal transfer between the cylinder liner 404 and the inter-bore section is less than the coefficient of thermal transfer between the cylinder liner 404 and other portions of the engine block. In this manner, the amount of heat transferred into the inter-bore section is reduced and the problems explained above, such as, for example, recession and cracking, are significantly reduced.

[0042] In the exemplary cylinder liner 404, the first engine block bonding surface 406 may extend around a substantial majority of the circumferential periphery of the cylinder liner 404. Further, in this exemplary cylinder liner 404, the first engine block bonding surface 406 is an as-cast rough surface while the second engine block bonding surface 408 may not have an as-cast rough surface.

[0043] FIGS. 5A and 5B provide perspective views of engine block 500 and 502 that, together, illustrate the reduction in the heat transfer from the cylinder bores into the inter-bore sections during operation as a result of the inventive cylinder liner. The engine block 500 includes conventional cylinder liners having an as-cast exterior rough surfaces which provide a high coefficient of thermal transfer between the cylinder bores and the engine block material in the inter-bore sections. In contrast, the engine block 502 includes cylinder liners of the present invention. In particular, the cylinder liners in the engine block 502 have a first engine block bonding surface with a higher heat transfer coefficient between the cylinder liner and the engine block material than a second engine block bonding surface that extends a substantial portion of the axial length of the cylinder liner and which is oriented adjacent to the inter-bore sections.

[0044] As is easily understood viewing FIGS. 5A and 5B, comparing the two engine blocks 500 and 502 during operation illustrates the inter-bore section 504 of the engine block 500 experiencing a higher temperature than the inter-bore section 506 of the engine block 502. In this manner, the properties of the engine block material for the engine block 502 in the inter-bore sections are not as adversely affected by higher temperatures as that of the engine block material in the engine block 500 in the inter-bore sections.

[0045] While the present description and exemplary embodiments refer to a first engine block bonding surface having an as-cast rough surface and a second engine block bonding surface having a machined or relatively smooth surface, it is to be understood that the present invention includes any type of surfaces so long as the coefficient of thermal transfer between the first engine block bonding surface and the engine block material is greater than that of the second engine block bonding surface and the engine block material.

[0046] This description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims.