Electromechanical Latch Pin Actuation via Magnetic Circuit Feedback
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Solution Overview
Problem
Hydraulically actuated latches in valvetrain systems for variable valve lift (VVL) or cylinder deactivation (CDA) are complex and oil-demanding, requiring separate hydraulic feeds and lacking on-board diagnostic capabilities.
Innovation Solution
The implementation of an electromechanical latch assembly with a rocker arm and a cam follower that uses an electromagnet to actuate a latch pin through a magnetic circuit, reducing complexity and oil demands, and enabling on-board diagnostics by analyzing magnetic flux and electrical circuit data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydraulically actuated latches are used for variable valve lift or cylinder deactivation, then the valvetrain system can achieve VVL or CDA functionality, but the system complexity and oil demand increase significantly
Solution Approach 1:
The patent replaces the hydraulic actuation system with an electromechanical latch assembly. Instead of using pressurized oil and hydraulic control valves to actuate the latch, an electromagnet is used to directly actuate the latch pin through magnetic force. This substitution eliminates the need for complex hydraulic feeds and oil pressure regulation systems, thereby reducing system complexity while maintaining VVL or CDA functionality.
2Adaptability or versatility
If hydraulically actuated latches are used for variable valve lift or cylinder deactivation, then the valvetrain system can achieve VVL or CDA functionality, but the oil demand approaches the limits of existing supply systems
Solution Approach 1:
The electromechanical latch assembly replaces the hydraulic actuation system, eliminating the need for pressurized oil feeds to the rocker arm assembly. The electromagnet actuates the latch pin using electrical energy converted to magnetic force, completely removing the oil demand associated with latch actuation and reducing the overall oil supply requirements of the valvetrain system.
3Ease of operation
If wires are attached to the rocker arm for electromagnet actuation, then the latch can be controlled, but the wires may be caught, clipped, or fatigued during rapid reciprocation
Solution Approach 1:
The patent extracts the electromagnet from the moving rocker arm assembly and mounts it on a stationary component such as the cylinder head or valve cover. This separation removes the wires and electrical connections from the high-speed reciprocating environment, eliminating the risk of wire fatigue, clipping, or shorting while maintaining electrical control capability through stationary wiring.
4Reliability
If the electromagnet is mounted on a component distinct from the rocker arm, then wire reliability is improved, but the magnetic circuit design becomes more complex
Solution Approach 1:
The patent introduces a stationary mounting component (cylinder head or valve cover) as an intermediary between the electromagnet and the rocker arm assembly. This intermediary provides a stable mounting platform for the electromagnet and serves as part of the magnetic circuit pathway, allowing the magnetic flux to travel through the stationary structure to actuate the latch pin on the moving rocker arm without requiring direct mechanical connection or complex flexible magnetic pathways.
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 valvetrain systems, reduces oil requirements, and provides on-board diagnostic capabilities for monitoring and managing engine operations, enhancing reliability and efficiency.
Implementation Method 1
The electromagnet is operative to cause the latch pin to translate between the first and second positions through magnetic flux following a magnetic circuit that includes a structural component of the valvetrain
Implementation Method 2
The actuator is operative on the latch pin through magnetic force and does not require a mechanical interface with the latch pin
Implementation Method 3
As the air gap varies in width, the magnetic reluctance of the magnetic circuit and the inductance of the electromagnet will also vary
Implementation Method 4
The inductance affects current and voltage in an electrical circuit that includes the electromagnet
Data Source
AI summary
A method of operating an internal combustion engine that includes a valvetrain having a rocker arm assembly including a rocker arm on which a latch pin is mounted. An actuator for the latch pin, including an electromagnet, is mounted separately from the rocker arm. Rocker arm position information is obtained by gathering and analyzing data relating to a current or voltage in an electrical circuit that is operative to power the electromagnet. The rocker arm position information is used to perform a diagnostic.