Inductive Length-Adjustable Connecting Rod for Engine Compression

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Solution Overview

Problem

Existing solutions for varying compression ratios in internal combustion engines are prone to wear, are space-consuming, and face challenges with inductive energy transmission, making them unreliable and costly.

Innovation Solution

A length-adjustable connecting rod with an induction device and excitation device that induces voltage during crankshaft rotation, allowing for rapid and efficient switching of compression ratios through an electrically actuated control valve, minimizing wear and optimizing space usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If magnetostrictive material is used for actuation, then compression ratio can be changed, but the material is susceptible to wear and reliable operation cannot be guaranteed

Engineering Contradiction:
Improvecompression ratio adjustmentVSAvoidoperational reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the magnetostrictive material-based mechanical actuation system with an inductive actuation system using an induction coil and ferromagnetic piston. The induction coil generates a magnetic field that actuates the ferromagnetic piston without direct contact, eliminating wear and improving reliability while maintaining compression ratio adjustability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If inductive actuation is used with induction coil in crankcase, then compression ratio switching is enabled, but difficulties arise due to contamination in transmission path

Engineering Contradiction:
Improvecompression ratio switchingVSAvoidinductive energy transfer reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent places the induction coil directly in the connecting rod near the control valve, creating a localized magnetic field environment. This eliminates the transmission path through the crankcase, preventing contamination from affecting the inductive energy transfer and ensuring reliable compression ratio switching.

Inventive Principle:
Principle #3Local quality

3Length of moving object

If control valve with actuating piston is used, then length adjustment is achieved, but the solution is space-consuming and requires complex manufacturing

Engineering Contradiction:
Improveconnecting rod length adjustmentVSAvoidcontrol valve structure
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The patent merges the induction coil, ferromagnetic piston, and control valve into a single integrated assembly within the connecting rod. The ferromagnetic piston serves both as the actuating element for the control valve and as the component responsive to the induction coil's magnetic field, simplifying the overall structure and reducing manufacturing complexity while maintaining length adjustment capability.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables flexible and reliable variation of compression ratios, reducing emissions and consumption, with efficient energy induction and storage, allowing for continuous operation with minimal wear and space-saving design.

Implementation Method 1

an electric current can be induced in the induction device by means of a crankshaft-mounted excitation device during a rotational movement of the crankshaft

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3390795B1Reciprocating-piston machine comprising a length-adjustable connecting rod and an inductively actuatable control valve
Publication Date: 2020.03.25 AVL LIST GMBH
  • EP3390795B1 patent drawingFigure 1~3
  • EP3390795B1 patent drawingFigure 4~6
  • EP3390795B1 patent drawingFigure 7~9

AI summary

The invention relates to a reciprocating-piston machine, in particular an internal combustion engine, comprising at least one length-adjustable connecting rod (1) connected to a crank pin (21) of a crankshaft (26), wherein the connecting rod (1) comprises at least one length-adjustment mechanism (6) and at least one electrically switchable and inductively actuatable control valve (7). According to the invention, in order to enable a flexible alteration of the compression ratio in the easiest, most space-saving and reliable manner possible, the connection rod (1) has at least one induction device (11) which is arranged in the region of a large connecting-rod eye (5) of the connecting rod (1), in a position in the connecting rod (1), extending from at least one end face (13) of the connecting rod (1) and separated from a longitudinal axis (21a) of the crank pin (21) by a crank pin distance (a), wherein the induction device (11) is or can be electrically connected to the control valve (7) and an electrical current can be induced in the induction device (11) during rotation of the crankshaft (20) by means of at least one starter device (14) attached to the crankshaft.