Engine Valve System With Hydraulic Lash Adjuster

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Solution Overview

Problem

Cam summation engine valve systems require adjustable clearances to compensate for manufacturing tolerances and thermal expansion, but existing designs either lack automatic lash adjustment or require significant packaging space, leading to potential damage and inefficiencies.

Innovation Solution

An engine valve system using two coaxially mounted cams with a summation rocker and a hydraulic lash adjuster, where a control spring and adjustable stop, such as a telescopically collapsible strut or flexible cable, set and maintain clearance when the cam followers are on the base circles of their cams, allowing for adjustable clearance without the need for extensive packaging or manual adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If an adjustable stop or graded shim is used to limit hydraulic lash adjuster expansion, then clearance can be adjusted, but the system requires significant packaging space and manual adjustment mechanisms

Engineering Contradiction:

Improveclearance adjustmentVSAvoidpackaging space

Core Design Contradiction:

Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The hydraulic lash adjuster automatically adjusts clearance through hydraulic expansion and compression based on engine operating conditions, eliminating the need for manual adjustment mechanisms and reducing packaging space requirements

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces mechanical clearance adjustment systems (adjustable stops, graded shims, manual adjustment mechanisms) with a hydraulic system that automatically maintains proper clearance through fluid pressure and volume changes

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a mechanical clearance adjustment system is used, then clearance can be controlled, but it cannot compensate for thermal expansion and component wear throughout the engine's life

Engineering Contradiction:

Improveclearance compensationVSAvoidadjustment mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The hydraulic lash adjuster changes its physical state and volume in response to temperature and pressure variations, automatically compensating for thermal expansion and component wear without requiring complex adjustment mechanisms

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The hydraulic system provides continuous feedback through oil pressure and volume changes, automatically adjusting clearance in response to engine operating conditions, thermal expansion, and component wear throughout the engine's operational life

Inventive Principle:

Principle #23Feedback

3Volume of moving object

If no clearance adjustment system is used, then packaging space is minimized, but manufacturing tolerances cause significant variations in valve lift between cylinders and potential damaging impact forces

Engineering Contradiction:

Improvepackaging spaceVSAvoidvalve lift consistency

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The hydraulic lash adjuster automatically compensates for manufacturing tolerances and maintains consistent valve lift across all cylinders without requiring additional packaging space for adjustment mechanisms

Inventive Principle:

Principle #25Self-service

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 retains the benefits of hydraulic lash adjustment while ensuring proper clearance control, reducing the risk of damage and optimizing engine performance by allowing for adjustable clearance without increasing packaging space or requiring manual adjustments during engine operation.

Implementation Method 1

a control spring is provided to urge the summation rocker in a direction to compress the hydraulic lash adjuster

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 2

a stop is associated with the control spring to limit the movement of the summation rocker towards the lash adjuster

Methodology Applied

Scientific EffectMechanical constraint:

Implementation Method 3

the use of a hydraulic lash adjuster can compensate for the effects of thermal expansion and component wear throughout the life of the engine

Methodology Applied

Scientific EffectThermal expansion compensation: Thermal Expansion

Data Source

PatentUS8794206B2Engine valve system

Publication Date: 2014.08.05 MECHADYNE INT LTD

AI summary

An engine valve system comprises two cams (10,12) mounted coaxially, a summation rocker (14) coupled to followers (16,18) of both cams and movable in proportion to the instantaneous sum of the lifts of the respective cams, and a valve actuating rocker (20) pivotably coupled to the summation rocker (14) and operative to open an engine valve (22) in dependence upon the movement of the summation rocker (14). In the invention, the actuating rocker (20) rests on a hydraulic lash adjuster (24). A control spring (136) is provided to urge the summation rocker (14) in a direction to compress the hydraulic lash adjuster (24). A stop (138) associated with the control spring (136) limits the movement of the summation rocker (14) towards the lash adjuster (24) so as to set the clearance in the valve system when the valve (22) is closed and the cam followers (16,18) are on the base circles of the two cams (10,12).