WO2017202775A1 - Connecting rod for an internal combustion engine with adjustable compression ratio - Google Patents

Connecting rod for an internal combustion engine with adjustable compression ratio Download PDF

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Publication number
WO2017202775A1
WO2017202775A1 PCT/EP2017/062282 EP2017062282W WO2017202775A1 WO 2017202775 A1 WO2017202775 A1 WO 2017202775A1 EP 2017062282 W EP2017062282 W EP 2017062282W WO 2017202775 A1 WO2017202775 A1 WO 2017202775A1
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WO
WIPO (PCT)
Prior art keywords
connecting rod
eccentrical element
eccentrical
internal combustion
combustion engine
Prior art date
Application number
PCT/EP2017/062282
Other languages
French (fr)
Inventor
Amadeu Crodelino
Evandro RUSSO
Bruno Mangueira VICENTIN
Original Assignee
ThyssenKrupp Metalúrgica Campo Limpo Ltda.
Thyssenkrupp Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ThyssenKrupp Metalúrgica Campo Limpo Ltda., Thyssenkrupp Ag filed Critical ThyssenKrupp Metalúrgica Campo Limpo Ltda.
Publication of WO2017202775A1 publication Critical patent/WO2017202775A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/04—Engines with variable distances between pistons at top dead-centre positions and cylinder heads
    • F02B75/045—Engines with variable distances between pistons at top dead-centre positions and cylinder heads by means of a variable connecting rod length
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C7/00—Connecting-rods or like links pivoted at both ends; Construction of connecting-rod heads
    • F16C7/06—Adjustable connecting-rods
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C23/00—Bearings for exclusively rotary movement adjustable for aligning or positioning
    • F16C23/10—Bearings, parts of which are eccentrically adjustable with respect to each other

Definitions

  • 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 piston 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 on the other hand.
  • 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.
  • 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 operatively 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 eccentrical element rods thereby actuate the eccentrical element lever.
  • the eccentric element lever comprises a through bore in which the eccentrical is mounted.
  • the eccentrical element is realized in each case in the prior art as an eccentric with a teethed outer circumferential surface.
  • the teeth on the outer circumferential surface of the eccentric engage a corresponding structuring on the border of the through bore of the eccentric element lever.
  • a first disadvantage of this approach is that providing both the eccentric element as well as the eccentric element lever with a teethed structuring is comparatively laboriously and costly.
  • the teeth generate geometric singularities such as the small radii between them where stresses consequently concentrate, reducing the structural strength of the components joint.
  • 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
  • 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 actuated with a force generated by hydraulic pressure in hydraulic cavities
  • the eccentrical element comprises an outer coupling zone which is non-rotatably coupled to an corresponding inner coupling zone of the eccentrical element lever and wherein said outer coupling zone presents a cross section with a trilateral, rectangular, pentagonal, chamfered, square, triangular, keyway or oval profile.
  • the chamfered profile can also be described as double-sided flattened round profile.
  • the outer coupling zone presents a section with a trilateral, rectangular, pentagonal, chamfered, square, triangular, keyway or oval profile which is connected by form-fit to the corresponding inner coupling zone of the eccentrical element lever.
  • the eccentrical element is located in a through bore of the eccentrical element lever.
  • the border of the through bore comprises the inner coupling zone and is preferably provided as negative shape of the outer coupling zone so that the structuring of the inner coupling zone and the structuring of the coupling outer zone engage each other.
  • the eccentric element and the eccentric element lever are connected to each other torque-proof and non-rotatably. Consequently, the eccentric element can be rotated by turning the eccentric element lever actuated by inertial and gas forces from the internal combustion engine. In this way, the effective length of the connecting rod is adjusted and therefore the compression ratio in the cylinder in which the connecting rod is located varies in order to achieve an increased fuel efficiency of the internal combustion engine.
  • said outer geometric shape of the eccentrical element comprises a trilobular profile.
  • a trilobular joint between the eccentric element and the eccentric element lever is realized providing a sturdy, simple and cost-efficient connection.
  • the eccentric element has a geometric shape similar to a triangle-round, wherein the roll diameter is substantially constant.
  • the outer geometric shape comprises three rounded vertices having smaller radii compared to the radii in the circumference ranges between the vertices.
  • the constant roll diameter and the absence of comparatively sharply angled teeth's as in the prior art strongly increases strength and durability of the connection between the eccentrical element and the eccentrical element lever.
  • the eccentrical element and the eccentrical element lever are connected to each other by press fit. It is herewith advantageously possible to implement not only a form-fit connection but simultaneously also a press-fit connection between the eccentrical element and eccentrical element lever. In this way, the mechanical strength of the connection can be increased. It is, moreover, ensured that the eccentrical element does not slip out of the through bore of the eccentric element lever during assembling the connecting rod and/or internal combustion engine.
  • the area spanned by the inner coupling zone is slightly smaller than the area spanned by the outer coupling zone.
  • the dimension of the eccentric element is slightly bigger than the dimension of the through bore in the eccentric element lever, so that said press-fit connection is formed when the eccentric element is pressed into the through bore.
  • Thermal assist assembling process such as heating lever and /or cooling down the eccentric may be applied to allow higher contact pressure after shrink fit connection.
  • a pure shrink is also conceivable,
  • an adhesive substance is provided at least partially between the outer coupling zone and the inner coupling zone.
  • the adhesive substance comprises a hardened threadlocker.
  • the adhesive substance supports the durability and strengths of the connection between the eccentric element and the eccentric element lever.
  • 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, wherein the at least one connecting rod is a connecting rod according to the present invention.
  • 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 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
  • Figure 4 illustrates schematically a connecting rod for an internal combustion engine with an adjustable compression ratio according to another exemplary embodiment of the present invention.
  • FIG 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.
  • 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 connecting rod 1 .
  • the connecting rod 1 In order to adjust the effective length l eff of the connecting rod 1 , the connecting rod
  • I 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-rotatably connected to an 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-rotatably to the eccentrical element 5, so that the eccentrical element 5 can be rotated by rotating the eccentrical element lever 6.
  • the eccentrical element lever 6 comprises two fixation points
  • each fixation point 1 1 one end of an eccentrical element rod 8 is mounted by means of a bolt 12.
  • the other end of the eccentrical element rod 8 is operatively connected to supporting pistons 10 in a hydraulic cavity 9 provided in the body of the connecting rod 1.
  • the hydraulic cavity 9 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 is explained e.g. in prior art document DE 10 2013 014 090 A1.
  • the torque-proof and non-rotatable connection between the eccentrical element 5 and the eccentrical element lever 6 is realized by a form-fit connection:
  • the outer circumferential surface of the eccentrical element 5 is provided with a plurality of teeth extending outwardly from the eccentrical element 5 and engaging a corresponding teeth structure at the inner border of the through bore 7 in the eccentrical element lever 6.
  • FIG 2 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 form-fit connection between the eccentrical element 5 and the eccentrical element lever 6 is provided as a trilobular joint between the eccentrical element 5 and the eccentrical element lever 6 instead of a toothed interlocking.
  • the eccentrical element 5 comprises an outer coupling zone at its circumferential surface having a trilateral profile. That means that the eccentric element 5 has a geometric shape similar to a triangle-round, wherein the roll diameter is substantially constant.
  • the coupling zone includes three rounded vertices having smaller radii compared to the radii in the circumference ranges between the vertices.
  • the roll diameter is always constant because a large rounding face and a small rounding face always oppose each other.
  • the eccentric element lever 6 comprises analogously a corresponding inner coupling zone at its inner border of the through bore 7.
  • the cross section of the through bore 7 corresponds in substance to the cross section of the eccentrical element 5.
  • the cross section of the through bore 7 is also a trilateral profile.
  • the eccentric element 5 is fully inserted into the through bore 7, so that a form-fit connecting between the eccentric element 5 and the eccentric element lever 7 is provided.
  • the constant roll diameter and the absence of comparatively sharply angled teeth increases strength and durability of this connection.
  • connection between the eccentrical element 5 and the eccentrical element lever 5 is not only a form-fit connection but additionally a press-fit connection.
  • the press-fit connection is realized by using an eccentrical element 5 having a trilateral profile with a slightly larger roll diameter as the roll diameter of the trilateral profile of the through bore 7 before inserting the eccentrical element 5 in to the through bore 7.
  • a force has to be applied onto both components, so that a press-fit and frictional connection is generated in order to improve the connection between the eccentrical element 5 and the eccentrical element lever 6 and to avoid any clearance between the components.
  • an adhesive substance is provided at least partially between the outer coupling zone and the inner coupling zone.
  • the adhesive substance comprises a hardened threadlocker.
  • the adhesive substance supports the durability and strengths of the connection between the eccentric element 5 and the eccentric element lever 6.
  • FIG 3 a detailed view of the eccentrical element 5 for the connecting rod 1 according to exemplary embodiment of the present invention is shown. It can be seen from figure 3 that the outer circumferential surface of the eccentrical element 5 describes a trilobular profile with three rounded vertices having smaller radii compared to the radii in the circumference ranges between the vertices, so that the eccentrical element 5 comprises a constant roll diameter.
  • FIG 4 a connecting rod 1 for an internal combustion engine with an adjustable compression ratio according to another exemplary embodiment of the present invention is shown.
  • the embodiment of figure 4 corresponds to embodiment of figure 2, as described above, whereas the inner and outer coupling zones each comprises a chamfered profile instead of a trilateral profile.
  • the chamfered profile can also be described as double-sided flattened round profile.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)

Abstract

The present invention refers to 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 the eccentrical element comprises an outer coupling zone which is non-rotatably coupled to an corresponding inner coupling zone of the eccentrical element lever, characterized in that said outer coupling zone presents a section with a trilateral, rectangular, pentagonal, square, triangular or oval profile. Furthermore, the present invention refers to an internal combustion engine comprising this connecting rod.

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 piston 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 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 operatively 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 eccentrical element rods thereby actuate the eccentrical element lever. The eccentric element lever comprises a through bore in which the eccentrical is mounted.
The eccentrical element is realized in each case in the prior art as an eccentric with a teethed outer circumferential surface. The teeth on the outer circumferential surface of the eccentric engage a corresponding structuring on the border of the through bore of the eccentric element lever. A first disadvantage of this approach is that providing both the eccentric element as well as the eccentric element lever with a teethed structuring is comparatively laboriously and costly. As another challenge, the teeth generate geometric singularities such as the small radii between them where stresses consequently concentrate, reducing the structural strength of the components joint.
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 which can be manufactured more easily and cost-effectively preserving or improving their functionality and lifetime.
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 actuated with a force generated by hydraulic pressure in hydraulic cavities, wherein the eccentrical element comprises an outer coupling zone which is non-rotatably coupled to an corresponding inner coupling zone of the eccentrical element lever and wherein said outer coupling zone presents a cross section with a trilateral, rectangular, pentagonal, chamfered, square, triangular, keyway or oval profile. The chamfered profile can also be described as double-sided flattened round profile.
According to the present invention, it is thereby advantageously possible to avoid manufacturing teethed surfaces on the inner and outer coupling zones so that the costs for manufacturing the connecting rod can be reduced substantially. For this purpose, the outer coupling zone presents a section with a trilateral, rectangular, pentagonal, chamfered, square, triangular, keyway or oval profile which is connected by form-fit to the corresponding inner coupling zone of the eccentrical element lever. In particular, the eccentrical element is located in a through bore of the eccentrical element lever. The border of the through bore comprises the inner coupling zone and is preferably provided as negative shape of the outer coupling zone so that the structuring of the inner coupling zone and the structuring of the coupling outer zone engage each other. Due to the fact that the inner coupling zone and the outer coupling zone respectively comprises a profile that is not axisymmetric, the eccentric element and the eccentric element lever are connected to each other torque-proof and non-rotatably. Consequently, the eccentric element can be rotated by turning the eccentric element lever actuated by inertial and gas forces from the internal combustion engine. In this way, the effective length of the connecting rod is adjusted and therefore the compression ratio in the cylinder in which the connecting rod is located varies in order to achieve an increased fuel efficiency of the internal combustion engine.
According to the present invention, it is preferred that said outer geometric shape of the eccentrical element comprises a trilobular profile. In this way, a trilobular joint between the eccentric element and the eccentric element lever is realized providing a sturdy, simple and cost-efficient connection. That means that the eccentric element has a geometric shape similar to a triangle-round, wherein the roll diameter is substantially constant. Particularly preferably, the outer geometric shape comprises three rounded vertices having smaller radii compared to the radii in the circumference ranges between the vertices. Advantageously, the constant roll diameter and the absence of comparatively sharply angled teeth's as in the prior art strongly increases strength and durability of the connection between the eccentrical element and the eccentrical element lever.
According to the present invention, it is preferred that the eccentrical element and the eccentrical element lever are connected to each other by press fit. It is herewith advantageously possible to implement not only a form-fit connection but simultaneously also a press-fit connection between the eccentrical element and eccentrical element lever. In this way, the mechanical strength of the connection can be increased. It is, moreover, ensured that the eccentrical element does not slip out of the through bore of the eccentric element lever during assembling the connecting rod and/or internal combustion engine. Preferably, the area spanned by the inner coupling zone is slightly smaller than the area spanned by the outer coupling zone. In other words: The dimension of the eccentric element is slightly bigger than the dimension of the through bore in the eccentric element lever, so that said press-fit connection is formed when the eccentric element is pressed into the through bore. Thermal assist assembling process such as heating lever and /or cooling down the eccentric may be applied to allow higher contact pressure after shrink fit connection. A pure shrink is also conceivable,
According to another preferred embodiment of the present invention, an adhesive substance is provided at least partially between the outer coupling zone and the inner coupling zone. In particular, the adhesive substance comprises a hardened threadlocker. Advantageously, the adhesive substance supports the durability and strengths of the connection between the eccentric element and the eccentric element lever.
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, wherein 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 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
Figure 4 illustrates schematically a connecting rod for an internal combustion engine with an adjustable compression ratio according to another 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 leff of the connecting rod 1 . In order to adjust the effective length leff of the connecting rod 1 , the connecting rod
I 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-rotatably connected to an 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-rotatably to the eccentrical element 5, so that the eccentrical element 5 can be rotated by rotating the eccentrical element lever 6. For this approach, the eccentrical element lever 6 comprises two fixation points
I I provided on opposite sides of the eccentrical element lever 6. In each fixation point 1 1 one end of an eccentrical element rod 8 is mounted by means of a bolt 12. The other end of the eccentrical element rod 8 is operatively connected to supporting pistons 10 in a hydraulic cavity 9 provided in the body of the connecting rod 1. The hydraulic cavity 9 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 is explained e.g. in prior art document DE 10 2013 014 090 A1.
The torque-proof and non-rotatable connection between the eccentrical element 5 and the eccentrical element lever 6 is realized by a form-fit connection: The outer circumferential surface of the eccentrical element 5 is provided with a plurality of teeth extending outwardly from the eccentrical element 5 and engaging a corresponding teeth structure at the inner border of the through bore 7 in the eccentrical element lever 6.
In figure 2, 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 form-fit connection between the eccentrical element 5 and the eccentrical element lever 6 is provided as a trilobular joint between the eccentrical element 5 and the eccentrical element lever 6 instead of a toothed interlocking.
The eccentrical element 5 comprises an outer coupling zone at its circumferential surface having a trilateral profile. That means that the eccentric element 5 has a geometric shape similar to a triangle-round, wherein the roll diameter is substantially constant. The coupling zone includes three rounded vertices having smaller radii compared to the radii in the circumference ranges between the vertices. Thus, the roll diameter is always constant because a large rounding face and a small rounding face always oppose each other. The eccentric element lever 6 comprises analogously a corresponding inner coupling zone at its inner border of the through bore 7. In particular, the cross section of the through bore 7 corresponds in substance to the cross section of the eccentrical element 5. Thus, the cross section of the through bore 7 is also a trilateral profile. The eccentric element 5 is fully inserted into the through bore 7, so that a form-fit connecting between the eccentric element 5 and the eccentric element lever 7 is provided. The constant roll diameter and the absence of comparatively sharply angled teeth increases strength and durability of this connection.
Optionally, the connection between the eccentrical element 5 and the eccentrical element lever 5 is not only a form-fit connection but additionally a press-fit connection. The press-fit connection is realized by using an eccentrical element 5 having a trilateral profile with a slightly larger roll diameter as the roll diameter of the trilateral profile of the through bore 7 before inserting the eccentrical element 5 in to the through bore 7. When the eccentrical element 5 is inserted into the through bore 7 a force has to be applied onto both components, so that a press-fit and frictional connection is generated in order to improve the connection between the eccentrical element 5 and the eccentrical element lever 6 and to avoid any clearance between the components.
Furthermore, it is conceivable that an adhesive substance is provided at least partially between the outer coupling zone and the inner coupling zone. Preferably, the adhesive substance comprises a hardened threadlocker. Advantageously, the adhesive substance supports the durability and strengths of the connection between the eccentric element 5 and the eccentric element lever 6.
In figure 3, a detailed view of the eccentrical element 5 for the connecting rod 1 according to exemplary embodiment of the present invention is shown. It can be seen from figure 3 that the outer circumferential surface of the eccentrical element 5 describes a trilobular profile with three rounded vertices having smaller radii compared to the radii in the circumference ranges between the vertices, so that the eccentrical element 5 comprises a constant roll diameter.
In figure 4, a connecting rod 1 for an internal combustion engine with an adjustable compression ratio according to another exemplary embodiment of the present invention is shown. The embodiment of figure 4 corresponds to embodiment of figure 2, as described above, whereas the inner and outer coupling zones each comprises a chamfered profile instead of a trilateral profile. The chamfered profile can also be described as double-sided flattened round profile.
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 supporting piston
10 hydraulic cavity
1 1 fixation point
12 bolt

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), wherein said eccentrical element (5) comprises an outer coupling zone which is non-rotatable coupled to a corresponding inner coupling zone of said eccentrical element lever (6), characterized in that said outer coupling zone presents a cross section with a trilateral, rectangular, pentagonal, chamfered, square, triangular, keyway or oval profile.
2. Connecting rod (1 ) according to claim 1 , wherein said inner coupling zone presents also a cross section with a trilateral, rectangular, pentagonal, chamfered, square, triangular, keyway or oval profile and wherein the inner zone and the outer zone are connected to each other by form fit.
3. Connecting rod (1 ) according to one of the preceding claims, wherein the outer geometric shape of the eccentrical element (5) comprises a trilobular profile.
4. Connecting rod (1 ) according to claim 3, wherein the outer geometric shape comprises three rounded vertices having smaller radii compared to the radii in the circumference ranges between the vertices.
5. Connecting rod (1 ) according to one of the preceding claims, wherein the eccentrical element (5) and the eccentrical element lever (6) are connected to each other by press fit.
6. Connecting rod (1 ) according to one of the preceding claims, wherein an adhesive substance is provided at least partially between the outer coupling zone and the inner coupling zone.
7. Connecting rod (1 ) according to claim 6, wherein the adhesive substance comprises a hardened threadlocker.
8. 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.
PCT/EP2017/062282 2016-05-25 2017-05-22 Connecting rod for an internal combustion engine with adjustable compression ratio WO2017202775A1 (en)

Applications Claiming Priority (2)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005055199A1 (en) 2005-11-19 2007-05-24 Fev Motorentechnik Gmbh Reciprocating internal combustion engine e.g. commercial vehicle diesel engine, has eccentric tappet moved along length of piston rod, where changeable resistor affects adjustment movement of tappet and effects adjustment movement of tappet
EP2103827A1 (en) * 2008-03-20 2009-09-23 Iprotec Maschinen- und Edelstahlprodukte GmbH Shaft-to-collar connection
DE102012020999A1 (en) 2012-07-30 2014-01-30 Fev Gmbh Hydraulic freewheel for variable engine parts
DE102013223746B3 (en) * 2013-11-21 2015-01-08 Schaeffler Technologies Gmbh & Co. Kg Device for changing the compression ratio of a cylinder unit of a reciprocating internal combustion engine
DE102013014090A1 (en) 2013-08-27 2015-03-05 Dr. Ing. H.C. F. Porsche Ag Internal combustion engine and connecting rod
DE102014109452A1 (en) * 2014-07-07 2016-01-07 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Connecting rod, method of making same and internal combustion engine
DE102014015113A1 (en) * 2014-10-10 2016-04-14 Daimler Ag Shaft-hub connection for a drive train of a motor vehicle, in particular a passenger car

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005055199A1 (en) 2005-11-19 2007-05-24 Fev Motorentechnik Gmbh Reciprocating internal combustion engine e.g. commercial vehicle diesel engine, has eccentric tappet moved along length of piston rod, where changeable resistor affects adjustment movement of tappet and effects adjustment movement of tappet
EP2103827A1 (en) * 2008-03-20 2009-09-23 Iprotec Maschinen- und Edelstahlprodukte GmbH Shaft-to-collar connection
DE102012020999A1 (en) 2012-07-30 2014-01-30 Fev Gmbh Hydraulic freewheel for variable engine parts
DE102013014090A1 (en) 2013-08-27 2015-03-05 Dr. Ing. H.C. F. Porsche Ag Internal combustion engine and connecting rod
DE102013223746B3 (en) * 2013-11-21 2015-01-08 Schaeffler Technologies Gmbh & Co. Kg Device for changing the compression ratio of a cylinder unit of a reciprocating internal combustion engine
DE102014109452A1 (en) * 2014-07-07 2016-01-07 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Connecting rod, method of making same and internal combustion engine
DE102014015113A1 (en) * 2014-10-10 2016-04-14 Daimler Ag Shaft-hub connection for a drive train of a motor vehicle, in particular a passenger car

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