Exhaust Valve Control System Phase Angle Adjustment
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Solution Overview
Problem
Exhaust interference in multi-cylinder engines with 180° crank angle intervals reduces charging efficiency and deteriorates low/middle speed performance, and existing solutions like exhaust manifolds or camshaft modifications are impractical due to engine layout constraints.
Innovation Solution
The method involves adjusting the phase angles of exhaust cam profiles between cylinders in two banks of an engine, where the angle between any two cylinders exceeds 180° by a predetermined amount, achieved by advancing or retarding specific cam profiles to minimize interference, while maintaining the same profiles and lifts across each bank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the exhaust manifold is shaped to minimize exhaust interference, then exhaust interference is reduced, but it is difficult to apply due to engine layout constraints
Solution Approach 1:
The invention changes the timing parameter of the exhaust cam profile by adjusting the phase angle between exhaust cams of different cylinders. Instead of modifying the physical shape of the exhaust manifold, the patent varies the angular position (phase angle) of the exhaust cam profiles to control the timing of exhaust valve opening and closing, thereby reducing exhaust interference while maintaining compatibility with existing engine layouts
Solution Approach 2:
The invention introduces variable timing control for exhaust valves by using different phase angles for different cylinders. This dynamic adjustment of cam timing allows the system to optimize exhaust gas flow patterns and reduce interference between adjacent cylinders, replacing the static exhaust manifold design with a dynamically adjustable cam timing system
2Object-affected harmful factors
If the profiles of the exhaust cams are adjusted to be different by machining the camshaft to have different thicknesses, then exhaust interference is reduced, but productivity is deteriorated due to grinding requirements
Solution Approach 1:
Instead of changing the physical dimensions of the camshaft through grinding, the invention changes the angular parameter (phase angle) of the cam profiles. This allows different timing characteristics to be achieved through simpler manufacturing processes such as indexing or positioning during cam installation, avoiding the time-consuming grinding operations while still reducing exhaust interference
3Productivity
If the angle between exhaust cam profiles is 180°, then the engine operates with standard timing, but exhaust interference occurs between cylinders with 180° ignition interval
Solution Approach 1:
The invention introduces asymmetry in the cam timing by setting different phase angles for different cylinders. Instead of using a uniform 180° interval for all exhaust cams, the patent applies asymmetric phase angle adjustments where certain cylinders have advanced or retarded timing relative to the base 180° interval, thereby breaking the symmetric pattern that causes exhaust interference
Data Source
AI summary
An exhaust valve control system of an engine includes a first bank including a plurality of cylinders and a second bank including a plurality of cylinder, in which the angle between the exhaust cam profiles of any two cylinders in the first bank is different by a predetermined angle or more from 180°, and the angle between the exhaust cam profiles of any two cylinders in the second bank is different by a predetermined angle or more from 180°.