Valve Gear Guide Element for Rocker Arm Tilting

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Solution Overview

Problem

In internal combustion engines with adjustable camshafts and axially divided cams, the asymmetrical transmission of force between the cam and rocker arm leads to tilting moments and uneven Hertzian pressure, causing premature wear and component failure.

Innovation Solution

A guide element with fork-shaped legs and wear-resistant guide surfaces is mounted on the cylinder head to provide precise lateral guidance for the rocker arm, absorbing tilting moments and ensuring uniform Hertzian pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If axially divided cams are used for variable valve control, then valve opening duration and phasing variability are improved, but asymmetrical force transmission causes tilting moments and uneven Hertzian pressure on the rocker arm

Engineering Contradiction:

Improvevalve control variabilityVSAvoidrocker arm durability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A guide element with guide surfaces is introduced as an intermediary component between the rocker arm and the cylinder head. This guide element mediates the asymmetrical forces by providing a lateral guidance function that counteracts tilting moments, allowing the rocker arm to maintain proper orientation while still benefiting from the variable valve control capabilities of the axially divided cams

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The guide element is designed with asymmetric guide surfaces that specifically counteract the asymmetrical force transmission caused by the divided cams. The guide surfaces are positioned and dimensioned to provide lateral guidance that balances the tilting moments generated during cam adjustment, transforming the asymmetric force problem into a controlled guidance mechanism

Inventive Principle:

Principle #4Asymmetry

2Ease of manufacture

If lateral guidance clearance is increased to facilitate assembly, then ease of assembly is improved, but guidance accuracy deteriorates allowing rocker arm lateral tilting

Engineering Contradiction:

Improveassembly easeVSAvoidlateral guidance accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The guide element provides localized precision guidance at the critical lateral guidance interface between the rocker arm and the guide element. By concentrating the guidance function in this specific location with precisely dimensioned guide surfaces, the system achieves high lateral guidance accuracy without requiring tight clearances throughout the entire assembly, facilitating easier assembly while maintaining precision where it matters most

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP2574744B1Valve gear for combustion engines with an adjustable camshaft

Publication Date: 2014.11.19 THYSSENKRUPP PRESTA TECCENTER AG

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AI summary

The valve train has a guide element (13) fixed at a cylinder head (1) of an internal combustion engine by an attachment element (15), for guiding pivoting movement of a rocker arm (18) i.e. roller rocker arm, in a plane. The guide element is properly matched with the rocker arm. The guide element comprises a mounting surface (10) that is attachable at the cylinder head and cooperates with a mounting surface (9) of the cylinder head. The guide element is inserted into the cylinder head as an insert mold part and cast in the cylinder head.