Variable Pivot-Axis Valve Timing for Dual-Fuel Engine Knock Control
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Solution Overview
Problem
Reciprocating engines, particularly dual fuel engines, face issues with knocking and misfire during varying load operations due to fluctuations in fuel composition, especially when the methane number of the gaseous fuel is less than 75, as existing charge changing control devices with only two modes fail to ensure proper operation in middle load ranges.
Innovation Solution
A charge changing control device with a cam follower system that can be pivotably actuated around a pivot axis upon rotational movement of a camshaft, featuring an adjustment unit to set at least three different charge-changing modes by displacing the pivot axis relative to the camshaft's rotational axis, allowing for optimized actuation timing adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charge changing control device with two charge-changing modes is used, then proper operation is ensured for high methane number fuels, but the device cannot prevent knocking or misfire in the middle load range when fuel methane number is less than 75
Solution Approach 1:
The invention makes the charge changing control device dynamically adjustable by enabling continuous variation of valve actuation timings through adjustable cam profiles. This allows the device to adapt to different fuel compositions and load ranges by optimizing valve timing for each operating condition, rather than being fixed in two discrete modes.
Solution Approach 2:
The invention changes the parameters of valve actuation timings by providing multiple adjustable cam profiles with different timing characteristics. This allows optimization of engine operation for different fuel types (methane numbers) and load ranges by selecting or adjusting the appropriate timing parameters.
2Device complexity
If valve timings are fixed for predefined operational modes, then the device structure remains simple, but the device cannot optimize performance across varying fuel compositions and operating conditions
Solution Approach 1:
The invention introduces dynamic adjustability to the valve timing system through adjustable cam profiles, allowing the system to optimize engine performance for different operating conditions while maintaining a relatively simple mechanical structure based on conventional cam follower mechanisms.
Data Source
AI summary
The present invention refers to a charge changing control device for a reciprocating engine, comprising at least one cam follower configured for being pivotably actuated around a pivot axis (P) upon rotational movement of a camshaft, and an adjustment unit configured for setting at least three different charge-changing modes of the device by translationally displacing the pivot axis relative (P) to a rotational axis (R) of the camshaft.