Welded Eccentric Connecting Rod for Adjustable Compression Ratio

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Solution Overview

Problem

Existing connecting rods for internal combustion engines with adjustable compression ratios require high production and assembly efforts due to meshing teeth on the eccentric and eccentric lever, leading to increased manufacturing costs and susceptibility to wear.

Innovation Solution

The eccentric is firmly connected to two eccentric lever segments of the eccentric lever via welding, eliminating the need for teeth and allowing for a stepped outer contour that simplifies assembly and enhances displacement, reducing manufacturing costs and wear susceptibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If meshing teeth are used to connect the eccentric to the eccentric lever, then the connection provides mechanical interlocking, but the manufacturing complexity and assembly effort increase significantly

Engineering Contradiction:

Improveconnection strengthVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical toothed connection system with a welding connection. The eccentric lever segment is welded directly to the eccentric body, eliminating the need for complex toothed interlocking mechanisms. This substitution of welding for mechanical interlocking reduces manufacturing complexity while maintaining connection strength.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent merges the eccentric lever segment and eccentric body into a single welded structure. By combining these two components through welding rather than using separate toothed components, the design simplifies manufacturing and assembly processes while achieving the required mechanical connection.

Inventive Principle:

Principle #5Merging (Combining)

2Strength

If meshing teeth are used to connect the eccentric to the eccentric lever, then the connection provides mechanical interlocking, but the susceptibility to wear increases

Engineering Contradiction:

Improveconnection strengthVSAvoidwear resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent replaces the mechanical toothed connection with a welded connection. Welding creates a continuous metal bond without the sliding contact between teeth that causes wear. This eliminates the wear mechanism inherent in toothed connections while maintaining strong mechanical coupling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If the eccentric lever is designed with slot-like recess for the eccentric, then the assembly process is simplified, but the manufacturing precision requirements increase

Engineering Contradiction:

Improveassembly simplicityVSAvoidrecess precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces the slot-like recess mechanical guidance system with a welding-based connection. Instead of requiring precise slot geometry for alignment, the welded connection tolerates greater dimensional variations, reducing manufacturing precision requirements while maintaining assembly simplicity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables a simpler and cost-effective assembly process with reduced wear, allowing for efficient adjustment of the connecting rod length and improved torque transmission while maintaining the adjustable compression ratio functionality.

Implementation Method 1

The eccentric lever segment (38, 39) of the eccentric lever (14) is connected to the eccentric (36) by welding

Methodology Applied

Scientific EffectWelding: Welding

Implementation Method 2

In the hydraulic chambers 22, 23 there is a hydraulic pressure which acts on the pistons 20, 21 assigned to the eccentric rods 15, 16

Methodology Applied

Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 3

allowing a lubricating oil film to form between the connecting rod bearing shell and the crankshaft journal

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentEP2843209B1Combustion engine and connecting rod

Publication Date: 2021.01.06 DR ING H C F PORSCHE AG

Figure 1
Figure 2
Figure 3~4

AI summary

Internal combustion engine having an adjustable compression ratio, with at least one cylinder and with a crankshaft to which at least one connecting rod (10) is attached, wherein the or each connecting rod (10) has a bearing eye (11) for connecting it to the crankshaft, a connecting rod bearing eye (12) for connecting it to a piston of a cylinder, and an eccentric adjusting device (13) for adjusting an effective connecting rod length, and wherein the eccentric adjusting device (13) has an eccentric (36) cooperating with an eccentric lever (14) and eccentric rods (15, 16) acting on the eccentric lever (14), which are acted upon by a hydraulic pressure prevailing in hydraulic chambers (22, 23) cooperating with the eccentric rods (15, 16), wherein the eccentric lever (14) has at least one eccentric lever segment (38, 39) exhibits, wherein the or each eccentric lever segment (38,39) is positioned in the axial direction of the eccentric (36) in front of and/or behind the connecting rod bearing eye (12), and wherein the eccentric lever segment or segments (38, 39) are rigidly connected to the eccentric (36). (Fig. 2)