Dynamic Cam Lobe Coupling for Variable Valve Actuation
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Solution Overview
Problem
Existing systems for variable valve actuation in internal combustion engines require additional hardware to control unneeded motion, which complicates the dynamic engagement or disengagement of cam lobes on the camshaft, leading to inefficiencies and increased complexity.
Innovation Solution
A cam-driven internal combustion engine system with a selectively disengagable cam lobe mechanism, utilizing a coupler to dynamically engage or disengage rotational force between the camshaft and cam lobes, allowing for activation or deactivation of valves on a cycle-by-cycle basis without additional hardware, controlled by a signal from a controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional spring return hardware is used to maintain follower contact with cam lobe, then reliable valve actuation is achieved, but device complexity increases
Solution Approach 1:
The patent removes the additional spring return hardware from the system by designing the cam lobe to maintain follower contact through its own geometric profile and rotational engagement mechanism. The cam lobe's shape and the coupling mechanism between the camshaft and cam lobe provide inherent contact maintenance without requiring separate return springs.
Solution Approach 2:
The patent combines the functions of cam lobe actuation and follower contact maintenance into a single integrated cam lobe design. The cam lobe simultaneously performs the valve actuation function and maintains follower contact through its geometric profile, eliminating the need for separate spring return components.
2Adaptability or versatility
If rigid collapsing follower is used to allow valve closed mode, then valve deactivation capability is achieved, but device complexity increases
Solution Approach 1:
The patent employs a dynamically engageable/disengageable cam lobe that can switch between active and inactive states. The cam lobe is coupled to the camshaft through a mechanism that allows it to rotate with the camshaft (active mode) or remain stationary (inactive mode), providing valve deactivation capability without complex additional hardware.
Solution Approach 2:
The cam lobe serves multiple functions: it acts as both the actuating element when engaged with the camshaft and the deactivation element when disengaged. The same cam lobe structure provides both valve actuation and valve deactivation capabilities, eliminating the need for separate mechanisms.
3Loss of energy
If dynamic engagement/disengagement of cam lobe is enabled, then fuel economy improves through reduced throttling losses, but device complexity increases
Solution Approach 1:
The patent introduces a coupling mechanism as an intermediary between the camshaft and cam lobe. This coupling mechanism (such as a clutch or engagement device) allows controlled connection and disconnection of the cam lobe from the camshaft, enabling dynamic valve deactivation to reduce throttling losses while maintaining manageable system complexity.
Data Source
AI summary
Disclosed is a method and system for intermittently operating poppet valves in an internal combustion engine when desired by the selective locking or unlocking of one or more cam lobes with the camshaft. One or more cam lobes, with a small radial clearance, ride on a camshaft such that an engagement mechanism may be activated as desired to lock the cam lobe to the camshaft, thereby activating the respective poppet valve. The cam lobe is prevented from moving axially to ensure correct alignment with a follower. A suitable holding device may be used to ensure the non-activated cam lobes are restrained at a suitable orientation relative to the cam follower.