Cylinder liner or cylinder block for an internal combustion engine

Abstract

The present application discloses a cylinder liner or cylinder block for an internal combustion engine, the cylinder liner or cylinder block comprising an inner side (2) forming a working surface, wherein the cylinder liner or cylinder block has at least one thermal isolation (4) extending in a circumferential direction around the cylinder liner or cylinder block, wherein the thermal isolation (4) is arranged spaced apart from the working surface in a radial direction.

Description

Technical Field

[0001] This application relates to the field of internal combustion engines, and more particularly to a cylinder liner or cylinder block for an internal combustion engine. Background Technology

[0002] Friction within the piston-piston ring-cylinder system can be categorized into contact friction, mixed friction, and hydraulic friction. Hydraulic friction constitutes a significant portion of the total friction. This is one of the main reasons why engine oil viscosity tends to decrease over time; hydraulic friction is directly proportional to oil viscosity, which in turn is temperature-dependent. Since cylinder block temperature typically peaks at top dead center (TDC) and peaks at bottom dead center (BDC) towards the crankcase, oil viscosity is lower at TDC, and increases progressively towards BDC.

[0003] Furthermore, hydraulic friction is directly proportional to piston speed. Since piston speed is highest in the middle of the piston stroke, it is desirable to have lower oil viscosity there in order to achieve low hydraulic friction.

[0004] From a friction perspective, it is ideal to have a higher oil viscosity at the dead center to reduce contact friction, while it is ideal to have a lower oil viscosity towards the center of the cylinder liner to reduce hydraulic friction.

[0005] DE 27 34 254 A1 discloses a cylinder liner for a reciprocating internal combustion engine, which is housed within a machine frame. The cylinder liner is effectively connected to a heat pipe, which is essentially configured as an outer sleeve, extending from a cooling water chamber to or up to a flange. The heat pipe has internal devices, such as capillary structures, that enable the transport of a liquid heat transfer medium along the cylinder tube, even against gravity.

[0006] DE 102 25 062B4 discloses a cylinder liner for a reciprocating internal combustion engine, wherein at least one first coolant passage is provided for the cylinder liner in the region of the piston's top dead center of the reciprocating internal combustion engine, and a set of second coolant passages are provided in the intermediate region of the cylinder liner and in the region of the piston's bottom dead center of the reciprocating internal combustion engine. Summary of the Invention

[0007] The objective of this application is to optimize the oil viscosity for positioning along the stroke.

[0008] According to a first aspect of this application, this application provides a cylinder liner or cylinder block for an internal combustion engine, the cylinder liner or cylinder block including an inner side forming a working surface, wherein the cylinder liner or cylinder block has at least one thermal isolation portion extending around the cylinder liner or cylinder block in a circumferential direction, wherein the isolation portion is disposed radially outwardly spaced from the working surface.

[0009] The advantage of the cylinder liner or cylinder block according to this application is that heat dissipation through the cylinder liner is reduced due to the isolation portion in the cylinder liner, resulting in lower oil viscosity and thus lower hydraulic friction in that area. The isolation portion of the cylinder liner or cylinder block can be continuous or can extend only in sections around the cylinder liner or cylinder block.

[0010] In one embodiment of the cylinder liner or cylinder block, the isolation portion forms a closed ring that extends around the entire cylinder liner or cylinder block.

[0011] Because the isolation section forms a closed ring around the entire cylinder liner or the entire cylinder block, optimal isolation is achieved without heat exchange occurring in the gap.

[0012] In another embodiment of the cylinder liner or cylinder block, the isolation portion is honeycomb or mesh-like and extends around the entire cylinder liner or cylinder block.

[0013] Compared to closed-loop isolation sections, honeycomb or mesh-like isolation sections have the advantage that the plates in such isolation sections absorb the load generated by the piston's movement within the cylinder liner or cylinder block. This reduces deformation and extends the service life of the cylinder liner or cylinder block.

[0014] In another exemplary embodiment of the cylinder liner or cylinder block, the cylinder liner or cylinder block has an outer side, wherein the isolation portion is exposed on the outer side.

[0015] Exposed isolation sections on the outside of the cylinder liner or cylinder block offer advantages in terms of manufacturing and maintenance techniques. These exposed isolation sections can also be created through painting or similar methods.

[0016] In one embodiment of the cylinder liner or cylinder block, the cylinder liner or cylinder block has an outer side, wherein an isolation portion is disposed between the working surface and the outer side.

[0017] In another embodiment of the cylinder liner or cylinder block, the isolation portion is implemented as a vacuum-sealed or fluid-filled cavity.

[0018] Vacuum insulation achieves thermal barrier by reducing heat transfer caused by air gas molecules. On one hand, a vacuum prevents convection; on the other hand, it prevents heat conduction by gas molecules. An example of preventing heat conduction by gas molecules is an embodiment based on a Dewar container.

[0019] In another embodiment of the cylinder liner or cylinder block, the cavity is filled with insulating material.

[0020] The advantages of filling the cavities of cylinder liners or cylinder blocks with insulating materials such as glass wool or asbestos are in terms of cost, maintenance, and manufacturing.

[0021] In embodiments of the cylinder liner or cylinder block, the working surface has a length L in the axial direction, wherein the isolation portion begins at a distance of 5-30%, preferably 10-25%, particularly preferably 15-20% and extends from there toward the crankcase.

[0022] The maximum length L of the working surface is measured from the upper edge of the cylinder liner or cylinder block, or the edge on the combustion chamber side. The area of ​​the isolation section is defined according to the above characteristics, because the height of the piston refractory blunt edge makes it unreasonable to start earlier, since the piston rings are not located in the hydraulically active area there. Furthermore, the temperature should just dissipate within the refractory blunt edge area for cooling.

[0023] In another embodiment of the cylinder liner or cylinder block, the piston stroke length along the axial direction between the top dead center and the bottom dead center is K, wherein the isolation portion begins at a distance of 5-30%, preferably 10-25%, particularly preferably 15-20% from the top dead center and extends from there in the direction of the bottom dead center.

[0024] The piston stroke length K is related to the piston movement of the engine, and is determined by the engine, specifically the cylinder liner or cylinder block. The area of ​​the isolation zone is defined by the above characteristics because the piston refractory blunt edge height makes early start unreasonable, since the piston rings are not located in the hydraulically active region there. Furthermore, the temperature should dissipate just within the refractory blunt edge region for cooling. The isolation zone can even extend beyond the bottom dead center.

[0025] In another embodiment of the cylinder liner or cylinder block, the radial thickness of the isolation portion and / or the thermal resistance of the isolation portion increases and / or first increases and then decreases in the axial direction from the combustion chamber to the crankcase.

[0026] The advantage of increasing and / or first increasing and then decreasing the radial thickness and / or thermal resistance of the isolation section in the axial direction from the combustion chamber to the crankcase is that it allows the oil viscosity to be optimally matched to the operating conditions.

[0027] In one embodiment of the cylinder liner or cylinder block, the isolation portion is provided in a region of the working surface at top dead center when the piston refractory blunt edge is located at a maximum operating temperature of 85-95%, preferably 88-92%, particularly preferably 89-91%, in the case of a conventional cylinder liner or cylinder block.

[0028] The isolation section is limited to the operating temperature range according to the aforementioned characteristics because cooling is required in higher operating temperature ranges, and heat dissipation should not be reduced as a result.

[0029] In another embodiment of the cylinder liner or cylinder block, at least one isolation portion is divided into 2 to 6 segments along the axial direction, and / or at least one isolation portion is divided into 2 to 72 segments or sub-regions along the circumferential direction.

[0030] The isolation section can be optimally matched to operating conditions in both the axial and circumferential directions to influence the oil viscosity on the working surface, thereby reducing friction. The axial direction here refers to the stroke direction. Sections along the axial direction are separated or isolated to varying degrees by tabs, while sections along the circumferential direction are similarly separated or isolated to varying degrees by tabs. The advantage of the tabs is that they absorb the load caused by the piston movement within the cylinder liner or cylinder block. This reduces deformation and extends the service life of the cylinder liner or cylinder block.

[0031] In another embodiment of the cylinder liner or cylinder block, the insulating material is selected from or constitutes the group consisting of: plastics, foam glass, titanium, mineral wool / glass wool, ceramic particles, composite materials, perlite and / or porous or foamed metals, such as cast iron, metal spray coatings or alloys.

[0032] In one embodiment of the cylinder liner or cylinder block, the insulating material has a porosity between 20-80%, preferably between 40-80%, and particularly preferably between 60-80%.

[0033] The isolation effect can be easily adjusted according to the requirements of operating conditions by adjusting the porosity.

[0034] In another embodiment of the cylinder liner or cylinder block, the cylinder liner or cylinder block is manufactured by 3D printing, and / or the isolation portion is made of sprayed metal and ceramic.

[0035] 3D printing allows for the creation of any arbitrary structure on demand with minimal material consumption. However, it is preferable to print or spray-plate only the insulating parts.

[0036] In another embodiment of the cylinder liner or cylinder block, the material of the insulating part is non-porous but conducts less heat than the material of the cylinder liner.

[0037] The low porosity allows for unrestricted load absorption, thereby reducing deformation and extending the service life of the cylinder liner or cylinder block. Attached Figure Description

[0038] Exemplary embodiments of this application are described in more detail below with reference to the accompanying drawings, wherein:

[0039] Figure 1 A cross-sectional view of a cylinder liner with thermal insulation is shown; and

[0040] Figure 2 A cross-sectional view is shown of a cylinder liner with inserted material in a thermal insulation section. Detailed Implementation

[0041] Figure 1A cross-sectional view of a cylinder liner according to an embodiment of this application is shown. The cylinder liner has an inner side 2, an outer side 6 forming a working surface for the piston, and a surrounding isolating portion 4.

[0042] At the upper end of the outer side 6 of the cylinder liner, there is a surrounding protrusion that allows the cylinder liner to fit precisely into the engine block. Additionally, at the upper end of the inner side 2 of the cylinder liner, there is a surrounding rectangular groove for a fire retardant ring. This fire retardant ring prevents the formation of hardened oil-carbon deposits on the refractory blunt edge of the piston. This is achieved by the fire retardant ring having an inner diameter smaller than the cylinder bore diameter. If the piston passes top dead center, the fire retardant ring scrapes unwanted oil-carbon deposits off the piston or prevents deposits that might form on the refractory blunt edge.

[0043] There is a surrounding thermal insulation portion in the middle region of the cylinder liner, separated from the upper and lower sides. This thermal insulation portion is constructed as a cavity. The cavity has a rectangular cross-section and the wall thickness at the same constant radial distance from the inner side 2 and the outer side 6 is equal.

[0044] Furthermore, the working surface length L and piston stroke length K can be observed. The working surface length L extends axially along the entire cylinder liner, while the piston stroke length K extends only to the end of the cavity. This means that the bottom dead center corresponds to the lower end of the thermal insulation section.

[0045] Figure 2 A cross-sectional view of a cylinder liner according to another embodiment of this application is shown. The cylinder liner has an inner side 2, an outer side 6 forming a working surface against the piston, and a surrounding isolating portion 4.

[0046] There is also a circumferential protrusion at the upper end of the outer side 6 of the cylinder liner, which allows the cylinder liner to fit precisely into the engine block. In addition, there is a circumferential rectangular groove at the upper end of the inner side 2 of the cylinder liner, which is provided for the fire-resistant ring.

[0047] A surrounding thermal insulation portion, formed by insert material within a cavity, is located in the intermediate region of the cylinder liner, spaced apart from the upper and lower sides. The cavity has a rectangular cross-section, is positioned at the outer 6th position of the cylinder liner, and has a constant radial thickness from the inner 2th position. The outer diameter of the insert material is equal to the outer diameter of the cylinder liner at each location.

[0048] Furthermore, the working surface length L and piston stroke length K can be observed. The working surface length L extends axially along the entire cylinder liner, while the piston stroke length K extends only to the end of the cavity. This means that the bottom dead center corresponds to the lower end of the thermal insulation section.

[0049] List of reference numerals

[0050] 2. Inner side

[0051] 4 Thermal insulation section

[0052] 6. Outer side

Claims

1. A cylinder liner or cylinder block for an internal combustion engine, said cylinder liner or cylinder block including an inner side forming a working surface (2). in, The cylinder liner or cylinder body has at least one thermal isolation portion (4), which extends around the cylinder liner or cylinder body in the circumferential direction, wherein the isolation portion (4) is arranged radially outward and spaced apart from the working surface; The isolation section (4) is mesh-like and extends around the entire cylinder liner or cylinder body, and the isolation section is made of sprayed metal and ceramic.

2. The cylinder liner or cylinder block according to claim 1, wherein, The isolation section (4) forms a closed ring that extends around the entire cylinder liner or cylinder block.

3. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The cylinder liner or cylinder block has an outer side (6), wherein the isolation portion (4) is exposed on the outer side.

4. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The cylinder liner or cylinder body has an outer side (6), wherein the isolation part (4) is disposed between the working surface and the outer side.

5. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The working surface has an axial length of L, wherein the isolation portion starts from a distance of 5-30% from the top dead center and extends from there toward the crankcase.

6. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The working surface has an axial length of L, wherein the isolation portion begins at a distance of 10-25% from the top dead center and extends from there toward the crankcase.

7. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The working surface has an axial length of L, wherein the isolation portion begins at a distance of 15-20% from the top dead center and extends from there toward the crankcase.

8. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The piston stroke length along the axial direction between the top dead center and the bottom dead center of the working surface is K, wherein the isolation part starts from 5-30% of the distance from the top dead center and extends from there in the direction of the bottom dead center.

9. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The piston stroke length along the axial direction between the top dead center and the bottom dead center of the working surface is K, wherein the isolation section starts from a distance of 10-25% from the top dead center and extends from there in the direction of the bottom dead center.

10. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The piston stroke length along the axial direction between the top dead center and the bottom dead center of the working surface is K, wherein the isolation section starts from 15-20% of the distance from the top dead center and extends from there in the direction of the bottom dead center.

11. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The radial thickness of the isolation section (4) and / or the thermal resistance of the isolation section (4) increases and / or first increases and then decreases in the axial direction from the combustion chamber to the crankcase.

12. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The isolation section (4) is located in the area where the temperature of the working surface is at most 85-95% of the operating temperature, wherein in the case of a conventional cylinder liner or cylinder block, the refractory blunt edge of the piston is located at the top dead center.

13. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The isolation section (4) is located in the area where the temperature of the working surface is at most 88-92% of the operating temperature, wherein in the case of a conventional cylinder liner or cylinder block, the refractory blunt edge of the piston is located at the top dead center.

14. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The isolation section (4) is located in the area where the temperature of the working surface is at most 89-91% of the operating temperature, wherein in the case of a conventional cylinder liner or cylinder block, the refractory blunt edge of the piston is located at the top dead center.

15. The cylinder liner or cylinder block according to claim 1 or 2, wherein, At least one isolation section (4) is divided into 2 to 6 sections along the axial direction, and / or at least one isolation section (4) is divided into 2 to 72 sections along the circumferential direction.

16. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The porosity of the insulating material is between 20% and 80%.

17. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The porosity of the insulating material is between 40% and 80%.

18. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The porosity of the insulating material is between 60% and 80%.

19. The cylinder liner or cylinder block according to claim 1 or 2, wherein, The cylinder liner or cylinder block is manufactured by 3D printing.

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