Electromagnetic Latch Cooling in Rocker Arm
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Solution Overview
Problem
Hydraulically actuated valvetrain systems face complexity and high oil demand issues, which can be mitigated by replacing hydraulic rocker arm assemblies with electromagnetic actuators, but packaging and cooling challenges arise with integrating electromagnetic latch assemblies within rocker arms.
Innovation Solution
The integration of an electromagnetic latch assembly within the rocker arm, featuring a cam follower, electromagnet, and oil cooling passageways that regulate oil flow to manage heat and reduce oil demand, allowing for variable valve lift and cylinder deactivation with reduced equipment costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If electromagnetic latch assembly is integrated within rocker arm, then packaging efficiency is improved, but cooling becomes challenging
Solution Approach 1:
The electromagnetic latch assembly is nested within the rocker arm housing, with the electromagnet positioned inside a dedicated chamber formed in the rocker arm. This nesting approach maximizes packaging efficiency while providing integrated cooling pathways through the rocker arm structure itself.
Solution Approach 2:
Engine oil acts as an intermediary cooling medium, flowing through passageways formed in the rocker arm to transfer heat away from the electromagnet. The oil serves as a heat transfer medium between the electromagnet and the external environment, enabling cooling without additional dedicated cooling systems.
2Temperature
If oil cooling passageways are added to rocker arm, then electromagnet cooling is improved, but device complexity increases
Solution Approach 1:
The rocker arm structure is designed to serve multiple functions simultaneously: it provides mechanical leverage for valve actuation, houses the electromagnetic latch assembly, and incorporates integrated cooling passageways. This multi-functionality reduces overall system complexity by combining what could be separate components into a single unified structure.
Solution Approach 2:
The cooling passageways are merged with the rocker arm manufacturing process, forming integral channels within the rocker arm body itself rather than adding separate cooling components. The passageways are formed during casting or machining of the rocker arm, combining structural and thermal management functions.
3Quantity of substance
If narrow passageways are used for oil cooling, then oil flow rate is reduced meeting supply limits, but cooling efficiency may be compromised
Solution Approach 1:
The passageway dimensions are optimized to specific parameter ranges that balance flow rate limitations with cooling efficiency. The passageways have carefully controlled cross-sectional areas and lengths that provide sufficient cooling while maintaining flow rates within supply system capabilities, representing an optimized parameter set rather than arbitrary dimensions.
Solution Approach 2:
The cooling passageways exhibit varying local characteristics, with narrower sections providing higher flow resistance to limit overall flow rate, and broader sections or extended pathways in regions requiring enhanced cooling. This local variation in passageway geometry allows simultaneous satisfaction of flow rate constraints and cooling requirements in different areas.
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 enables efficient dynamic cylinder deactivation and variable valve actuation by maintaining the electromagnet at a stable temperature below 190°C, reducing the need for continuous power and minimizing oil supply demands, while allowing for distinct valve lift profiles and deactivation.
Implementation Method 1
The electromagnetic latch assembly includes a latch pin translatable between a first position and a second position and an electromagnet
Implementation Method 2
passageways suitable for oil cooling of the electromagnet are formed through and inside the rocker arm
Implementation Method 3
Some of the passageways may allow oil to flow adjacent to the electromagnet inside the rocker arm
Data Source
AI summary
A valvetrain includes a rocker arm assembly having a rocker arm and an electromagnetic latch assembly. An electromagnet of the latch assembly is housed within a chamber formed by the rocker arm. Passageways suitable for oil cooling of the electromagnet are formed through and inside the rocker arm. In some embodiments, oil for cooling is supplied through a pivot. In some embodiments, oil for cooling is obtained from oil splash. Oil cooling may allow modes of operation such as of dynamic cylinder deactivation and dynamic variable valve actuation to be used without overheating the electromagnet.