Engine Valve Actuation with Recompression Relief for Cylinder Pressure Control

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Solution Overview

Problem

The use of cam phasers in internal combustion engines can lead to high cylinder pressure and objectionable noise due to the advancement of the exhaust main valve event, which eliminates the overlap with the intake main valve event.

Innovation Solution

A recompression relief valve event is introduced, which is provided by a motion source configured to overlap with the intake main valve event, thereby reducing cylinder pressure and mitigating noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If cam phasers advance the exhaust main valve event phase, then power generation efficiency is improved, but cylinder pressure increases and noise becomes objectionable

Engineering Contradiction:

Improvepower generation efficiencyVSAvoidcylinder pressure and noise

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The exhaust valve actuation is segmented into two separate events: the main exhaust valve event for power generation and a recompression relief valve event for pressure control. This segmentation allows independent optimization of each function - the main event can be advanced for efficiency while the relief event manages cylinder pressure and noise separately

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A lost motion component acts as an intermediary mechanism between the cam phaser and the exhaust valve. This intermediary selectively transmits or blocks valve events based on cam phase, enabling the recompression relief valve event to be activated only when needed for pressure relief while maintaining the advanced phase for power generation efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If cam phasers advance the exhaust main valve event phase, then valve timing is optimized, but overlap with intake valve event is eliminated causing high cylinder pressure

Engineering Contradiction:

Improvevalve timing optimizationVSAvoidcylinder pressure

Core Design Contradiction:

Ease of operationVSStress or pressure

Solution Approach 1:

The recompression relief valve event is activated in advance of the main intake valve opening to preemptively reduce cylinder pressure. This preliminary action prevents the buildup of high pressure that would otherwise occur when the advanced exhaust valve eliminates overlap with the intake valve

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the timing parameter of the exhaust valve by introducing the recompression relief valve event at a specific phase angle before the main intake valve opens. This parameter change creates a pressure relief window that mitigates the high cylinder pressure caused by advanced exhaust valve timing

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250116213A1System and method for actuating engine valves including a recompression relief valve event

Publication Date: 2025.04.10 JACOBS VEHICLE SYSTEMS INC

AI summary

A valve actuation system for actuating at least one of two or more engine valves in an internal combustion engine comprises at least one motion source including a first motion source configured to provide an exhaust main valve event. A valve train for conveying valve events from the at least one motion source to the two or more engine valves comprises a lost motion component for selectively conveying valve events to the at least one of the two or more engine valves. A phasing assembly is configured to advance a phase of at least the first motion source and the exhaust main valve event. The at least one motion source is configured to provide a recompression relief valve event to the at least one of the two or more engine valves when the phase of the exhaust main valve event is advanced.