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Title:
CONNECTING ROD FOR AN INTERNAL COMBUSTION ENGINE WITH ADJUSTABLE COMPRESSION RATIO
Document Type and Number:
WIPO Patent Application WO/2017/202773
Kind Code:
A1
Abstract:
The present invention refers to a connecting rod (1) for an internal combustion engine with an adjustable compression ratio comprising a crank pin bearing eye (2) for connecting the connecting rod (1) to a crank shaft of the internal combustion engine, a connecting rod bearing eye (3) for connecting said connecting rod (1) to a cylinder piston of said internal combustion engine and an eccentrical element adjustment device (4) for adjusting the distance between said crank pin bearing eye (2) and said connecting rod bearing eye (3), wherein said eccentrical element adjustment device (4) comprises an eccentrical element (5) including said connecting rod bearing eye (3), an eccentrical element lever (6) and eccentrical element rods (8) engaging the eccentrical element lever (6), wherein said eccentrical element rods (8) are loaded with a force generated by hydraulic pressure in hydraulic cavities (9), wherein an outer surface (11) of the eccentric element (5) and/or an inner surface (12) at the border of the connecting rod bearing eye (3) is provided with a texture (10).

Inventors:
HACKER, Patrick Ansgar (Rua Engenheiro Hermenegildo Campos de Almeida 261, Apt 121 - Vila Japi 2, -640 Jundiai - São Paulo, 13208-640, BR)
Application Number:
EP2017/062280
Publication Date:
November 30, 2017
Filing Date:
May 22, 2017
Export Citation:
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Assignee:
THYSSENKRUPP METALÚRGICA CAMPO LIMPO LTDA. (Av Alfried Krupp 1050, -900 Campo Limpo Paulista SP, 13231-900, BR)
THYSSENKRUPP AG (ThyssenKrupp Allee 1, Essen, 45143, DE)
International Classes:
F02B75/04; F16C7/06
Foreign References:
DE102014103585B32015-09-03
DE102013223746B32015-01-08
DE102013224270B32015-01-08
DE102012020999A12014-01-30
DE102012020999A12014-01-30
DE102013014090A12015-03-05
DE102005055199A12007-05-24
Attorney, Agent or Firm:
THYSSENKRUPP INTELLECTUAL PROPERTY GMBH (ThyssenKrupp Allee 1, Essen, 45143, DE)
Download PDF:
Claims:
PATENT CLAIMS

1 . Connecting rod (1 ) for an internal combustion engine with an adjustable compression ratio comprising a crank pin bearing eye (2) for connecting the connecting rod (1 ) to a crank shaft of the internal combustion engine, a connecting rod bearing eye (3) for connecting said connecting rod (1 ) to a cylinder piston of said internal combustion engine and an eccentrical element adjustment device (4) for adjusting the distance between said crank pin bearing eye (2) and said connecting rod bearing eye (3), wherein said eccentrical element adjustment device (4) comprises an eccentrical element (5) including said connecting rod bearing eye (3), an eccentrical element lever (6) and eccentrical element rods (8) engaging the eccentrical element lever (6), wherein said eccentrical element rods (8) are actuated with a force generated by hydraulic pressure in hydraulic cavities (9), characterized in that an outer surface (1 1 ) of the eccentric element (5) and/or an inner surface (13) of the connecting rod bearing eye (3) is provided with a texture (12).

2. Connecting rod (1 ) according to claim 1 , wherein said texture (12) comprises a laser- structured surface.

3. Connecting rod (1 ) according to claim 2, wherein said laser-structured surface comprises a plurality of craters.

4. Connecting rod (1 ) according to one of the preceding claims, wherein the texture (12) comprises a plurality of dimples each providing a potential lubricant reservoir.

5. Connecting rod (1 ) according to one of the preceding claims, wherein the dimples have a diameter between 50 to 1 10 micrometers and preferably of around 74 micrometers.

6. Connecting rod (1 ) according to one of the preceding claims, wherein the dimples have a depth between 3 to 10 micrometers and preferably of around 5 micrometers.

7. Connecting rod (1 ) according to claim 1 , wherein said texture (12) comprises a mechanical-structured surface, more preferably produced by lapping or grinding.

8. Connecting rod (1 ) according to one of the preceding claims, wherein the outer surface (1 1 ) of the eccentric element (5) and/or the inner surface (13) of the connecting rod bearing eye (3) is provided with a coating.

9. Internal combustion engine with an adjustable compression ratio comprising at least one cylinder and a crank shaft at which at least one connecting rod (1 ) engages, characterized in that the at least one connecting rod (1 ) is a connecting rod (1 ) according to one of the preceding claims.

Description:
DESCRIPTION

Title

Connecting rod for an internal combustion engine with adjustable compression ratio Background

Internal combustion engines with adjustable compression ratio are commonly known from the prior art.

By way of example, prior art documents DE 10 2012 020 999 A1 , DE 10 2013 014 090 A1 and DE 10 2005 055 199 A1 disclose internal combustion engines with a cylinder and a crank shaft coupled with each other by means of a connecting rod having an adjustable effective length e.g. in order to increase fuel efficiency of the internal combustion engines under varying loads.

The connecting rod comprises a crank pin bearing eye for connecting the connecting rod to the crank shaft on the one hand and a connecting rod bearing eye for connecting the connecting rod to a cylinder piston by using a piston pin on the other hand. In order to adjust the effective length of the connecting rod, the connecting rod comprises an eccentrical element adjustment device for adjusting the effective distance between the crank pin bearing eye and the connecting rod bearing eye. For this purpose, the eccentrical element adjustment device comprises an eccentrical element including the connecting rod bearing eye, an eccentrical element lever non-rotatably connected to the eccentrical element and two eccentrical element rods engaging the eccentrical element lever. The eccentrical element rods are opera- tively connected to hydraulic cavities in the body of the connecting rod in order to generate a force onto the eccentrical element rods generated by hydraulic pressure. The eccentric element lever comprises a through bore in which the eccentrical is mounted.

Consequently, the eccentrical element comprises an outer surface being in mechanical contact with the inner wall of the through hole of the eccentric element lever and the through hole of connecting rod bearing eye. Furthermore, the eccentrical element comprises an inner surface at the connecting rod bearing eye being in mechanical contact with the outer surface of the piston pin. The eccentrical element may be subjected to an increased wear and friction due to the above mentioned mechanical contacts. Disadvantageously, the foregoing leads to a decreased lifetime of the eccentrical element and therefore of the whole connecting rod.

A solution is to provide a Diamond like Carbon (DLC) coating on the components, but a DLC coating is comparatively expensive and would therefore increase the components cost.

Summary of invention

It is therefore an object of the present invention to provide a connecting rod for an internal combustion engine machine with an adjustable compression ratio and a corresponding combustion engine machine with less wear at the contact surfaces of the eccentrical element and an extended lifetime which is more cost-efficient.

The object of the present invention is achieved by a connecting rod for an internal combustion engine with an adjustable compression ratio comprising a crank pin bearing eye for connecting the connecting rod to a crank shaft of the internal combustion engine, a connecting rod bearing eye for connecting the connecting rod to a cylinder piston of the internal combustion engine and an eccentrical element adjustment device for adjusting the distance between the crank pin bearing eye and the connecting rod bearing eye, wherein the eccentrical element adjustment device comprises an eccentrical element including the connecting rod bearing eye, an eccentrical element lever and eccentrical element rods engaging the eccentrical element lever, wherein the eccentrical element rods are loaded with a force generated by hydraulic pressure in hydraulic cavities, wherein an outer surface of the eccentric element and/or an inner surface at the connecting rod bearing eye is provided with a texture.

According to the present invention, it is thereby advantageously possible to provide less mechanical wear and friction at the inner and/or outer surfaces of the eccentrical element due to a better lubrication effect, so that an improved lifetime can be achieved. The better lubrication effect arises from the textured surfaces as the texture leads to a stabilized lubrication film in the lubrication gap between both components. Furthermore, heat in the contact zone between the inner surface of the eccentrical element and the outer surface of the piston pin which connects the eccentrical element to the cylinder piston or between the inner surface of the connecting rod bearing eye and the outer surface of the eccentrical element will be reduced due to the better lubrication effect. According to a preferred embodiment of the present invention, the said texture comprises laser-structured surface. This has the advantage that the texture can be provided on the eccentric element in a comparatively simple and cost-efficient manner. The texture and in particularly said laser-structured surface comprises a plurality of melt craters generated during the laser treatment.

According to a preferred embodiment of the present invention, the texture comprises a plurality of dimples each providing a potential lubrication reservoir. Advantageously, the volume of the dimples and the dimple density allow the eccentrical element to support higher pressures due to the compression of oil in the dimples. Furthermore, a dry contact between the surfaces of the components is avoided due to the better lubrication, so that wear is reduced. Preferably, the dimples have a diameter between 50 to 1 10 micrometers and preferably of around 74 micrometers. Particularly preferably, the dimples have a depth between 3 to 10 micrometers and preferably of around 5 micrometers.

According to a preferred embodiment of the present invention, said texture comprises mechanical-structured surface, more preferably produced by lapping or grinding.

According to a preferred embodiment of the present invention, the outer surface of the eccentric element and/or the inner surface at the connecting rod bearing eye is provided with a coating. The coating preferably comprises a carbon-based coating, e.g. Diamond like Carbon (DLC) coating. The coating is applied e.g. by physical or chemical vapour deposition (PVD or CVD), plasma spray or the like.

Another subject of the present invention is an internal combustion engine with an adjustable compression ratio comprising at least one cylinder and a crank shaft at which at least one connecting rod engages, characterized in that the at least one connecting rod is a connecting rod according to the present invention.

These and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

Brief description of the drawings Figure 1 illustrates schematically an exemplary connecting rod for an internal combustion engine having an adjustable compression ratio as known from the prior art

Figure 2 illustrates schematically a detailed view of a connecting rod for an internal combustion engine with an adjustable compression ratio according to an exemplary embodiment of the present invention.

Figure 3 shows a detailed view of the eccentrical element for the connecting rod according to the exemplary embodiment of the present invention

Detailed description

The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes.

Where an indefinite or definite article is used when referring to a singular noun, e.g. "a", "an", "the", this includes a plural of that noun unless something else is specifically stated.

Furthermore, the terms first, second, third and the like in the description and in the claims are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described of illustrated herein.

In figure 1 , an exemplary connecting rod for an internal combustion engine having an adjustable compression ratio as known from the prior art is shown.

The connecting rod 1 is provided for connecting a crank shaft (not shown) of the internal combustion engine with a cylinder piston (not shown) of the internal combustion engine. For this approach, the connecting rod 1 comprises a crank pin bearing eye 2 for connecting the connecting rod 1 to the crank shaft and a connecting rod bearing eye 3 for connecting the connecting rod 1 to the cylinder piston.

The internal combustion engine has an adjustment mechanism to adjust the compression ratio inside the cylinder. This is achieved by adjusting the effective length l eff of the connect- ing rod 1 . In order to adjust the effective length l eff of the connecting rod 1 , the connecting rod 1 comprises an eccentrical element adjustment device 4 for adjusting the distance between the connecting rod bearing eye 3 and the crank pin bearing eye 2.

The eccentrical element adjustment device 4 comprises an eccentrical element 5 including the connecting rod bearing eye 3. The eccentrical element 5 is non-rotatable connected to a single-piece or multi-piece eccentrical element lever 6. The eccentrical element lever 6 comprises a through bore 7 in which the eccentrical element 5 is mounted. The connecting rod bearing eye 3 is located outside the rotational center of the eccentrical element 5, so that rotating the eccentrical element 5 varies the distance between the connecting rod bearing eye 3 and the crank pin bearing eye 2. The eccentrical element lever 6 is torque-proof and non-rotatable to the eccentrical element 5, so that the eccentrical element 5 can be rotated by turning the eccentrical element lever 6. For this approach, the eccentrical element lever 6 comprises two fixation points 9 provided on opposite sides of the eccentrical element lever 6. In each fixation point 9 one end of an eccentrical element rod 8 is mounted by means of a bolt 10. The other end of the eccentrical element rod 8 is operatively connected to a hydraulic cavity (not shown) provided in the body of the connecting rod 1 . The hydraulic cavity is filled with oil in order to generate a force onto the eccentrical element rods 8 generated by hydraulic pressure, as known from the prior art. The function of the hydraulic system and the eccentrical element rods 8 rotating eccentrical element lever 6 explained e.g. in prior art document DE 10 2013 014 090 A1 .

In figure 2, a detailed view of a connecting rod 1 for an internal combustion engine with an adjustable compression ratio according to an exemplary embodiment of the present invention is illustrated.

The connecting rod 1 according to the present invention substantially corresponds to the connecting rod 1 , shown in figure 1 , whereas the circumferential outer surface 1 1 of the eccentrical element 5 is provided with a texture 12. The same applies to the inner surface 13 of the eccentrical element 5 which is the border of the connecting rod bearing eye 3. The inner surface 13 of the eccentrical element 5 is also provided with a texture 12.

In both cases, the texture 12 is formed by a plurality of dimples, wherein each dimple works as a potential lubrication reservoir. The dimples can be melt craters produced by laser treatment of the inner and outer surfaces 1 1 , 13. It is conceivable that the dimples have a diameter between 50 to 1 10 micrometers, preferably around 74 micrometers and that the dimples have a depth between 3 to 10 micrometers, preferably around 5 micrometers. In figure 3, a detailed view of the eccentrical element 5 for the connecting rod 1 according to the exemplary embodiment of the present invention is shown. It can be seen from figure 3 that the circumferential outer surface 1 1 of the eccentrical element 5 is provided with a texture 12 in the form of a plurality of dimples and that also the inner surface 13 of the eccentrical element 5 is provided with a texture 12 in the form of a plurality of dimples.

Preferably, the outer surface 1 1 of the eccentric element 5 and the inner surface 13 at the connecting rod bearing eye 3 is provided with a coating, e.g. a Diamond like Carbon (DLC) coating applied e.g. by physical or chemical vapour deposition (PVD or CVD).

Reference signs

1 connecting rod

2 crank pin bearing eye

3 connecting rod bearing eye

4 eccentrical element adjustment device

5 eccentrical element

6 eccentrical element lever

7 through bore

8 eccentrical element rod

9 fixation point

10 bolt

1 1 outer surface of the eccentrical element

12 texture

13 inner surface of the eccentrical element