Electromagnetic Rocker Arm Latch for Low-Oil Valvetrains
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Solution Overview
Problem
The complexity and oil demand of hydraulically latched rocker arm assemblies in valvetrain systems for internal combustion engines, particularly those with variable valve lift (VVL) or cylinder deactivation (CDA), pose challenges in terms of system efficiency and equipment cost.
Innovation Solution
The method involves replacing hydraulically latched rocker arm assemblies with electrically latched rocker arm assemblies, utilizing electromagnetic latch assemblies with permanent magnets and solenoids to provide dual positional stability and reduce oil consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydraulically latched rocker arm assemblies are used to implement variable valve lift or cylinder deactivation, then the valvetrain system can achieve multiple valve lift profiles and cylinder deactivation, but the system complexity and oil demand increase significantly
Solution Approach 1:
The patent replaces the hydraulic latch system with an electromagnetic latch system. The electromagnetic latch uses a solenoid to actuate a latch pin that engages or disengages the rocker arm from the cam follower, thereby switching between different valve lift profiles. This substitution eliminates the need for complex hydraulic feeds, oil control valves, and pressure regulation systems while maintaining the ability to provide multiple valve lift profiles and cylinder deactivation functionality.
2Adaptability or versatility
If hydraulically latched rocker arm assemblies are used, then variable valve lift and cylinder deactivation are achieved, but the equipment cost and oil consumption increase
Solution Approach 1:
The electromagnetic latch system replaces the hydraulic system, eliminating oil consumption entirely for latch actuation. The solenoid uses electrical energy to magnetize a ferromagnetic latch pin, which mechanically engages or disengages the rocker arm. This substitution removes the need for hydraulic oil feeds, pressure regulators, and associated components, thereby reducing both oil consumption and equipment cost while maintaining cylinder deactivation capability.
3Stability of the object's composition
If permanent magnets are used in the electromagnetic latch assembly, then dual positional stability is achieved, but ferromagnetic particles in oil may be drawn to the magnet locations
Solution Approach 1:
The patent extracts the permanent magnets from the direct path of oil flow and positions them within sealed chambers in the rocker arm assembly. The latch pin, which is ferromagnetic, translates through a path that is sealed from oil contamination. The permanent magnets are contained within these sealed chambers, preventing oil-borne metal particles from being drawn to the magnet locations. This extraction and sealing approach maintains dual positional stability while eliminating the harmful effect of particle attraction.
4Reliability
If the solenoid is continuously powered to maintain latch position, then reliable positioning is achieved, but energy consumption increases
Solution Approach 1:
The electromagnetic latch system uses periodic action through the use of permanent magnets that provide continuous holding force without requiring continuous electrical power. The solenoid is energized only transiently to switch the latch pin between positions (engaged or disengaged). Once positioned, the permanent magnets maintain the latch position reliably without continuous power input. This periodic actuation approach maintains reliable positioning while minimizing energy consumption compared to continuous solenoid powering.
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 simplifies the valvetrain system, reduces oil demand, and provides a more compact design by eliminating the need for complex hydraulic systems and minimizing solenoid operation to only when necessary.
Implementation Method 1
A solenoid or a permanent magnet forming part of the electromagnetic latch assembly is mounted to the rocker arm. In embodiments, each of the permanent magnets is mounted within a chamber formed by the corresponding rocker arm.
Implementation Method 2
The electromagnetic latch assembly comprises a latch pin translatable between a first position and a second position
Data Source
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AI summary
A valvetrain includes a rocker arm assembly having an electromagnetic latch housed in a chamber formed by a rocker arm. The chamber may be a retrofit hydraulic chamber. A flux shifting bi-stable latch provides a sufficiently compact design. Isolation of the magnetic elements within the rocker arm chamber may provide protection from metal particles carried by oil in an operating environment for the rocker arm assembly. Wiring connections to the rocker arms may be made through spring posts on the rocker arms. Connection to the rocker arms may be made with springs that can endure the rapid motion induced by the rocker arms. A wiring harness for the rocker arms may attach to hydraulic lash adjusters of the rocker arm assemblies. The rocker arm assemblies and their wiring may be formed into a unitary module that facilitates installation.