Rocker Arm Magnetic Latch with Off-Arm Actuation
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Solution Overview
Problem
Existing valvetrain systems with hydraulic latches for variable valve lift (VVL) or cylinder deactivation (CDA) face complexity and high oil demand, which can strain existing supply systems.
Innovation Solution
The implementation of solenoid-actuated magnetic latches in rocker arm assemblies, which replace hydraulic latches, allowing for a compact design with reduced oil demands and simplified wiring by mounting the actuator off the rocker arm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydraulic latches are used in rocker arm assemblies, then variable valve lift and cylinder deactivation functions are achieved, but system complexity and oil demand increase
Solution Approach 1:
The patent replaces the hydraulic actuation system with a magnetic latch system. Instead of using pressurized oil to actuate the latch, a magnetic field generated by a solenoid actuator is used to engage and disengage the latch pin. This substitution eliminates the need for hydraulic feeds to each rocker arm, reducing system complexity while maintaining the variable valve lift and cylinder deactivation functions
Solution Approach 2:
The magnetic latch system serves multiple functions: it enables variable valve lift mode, cylinder deactivation mode, and can be actuated by a single hydraulic feed or electrical signal. The latch mechanism itself is universal across different rocker arm assemblies, requiring only the actuation method to change from hydraulic to magnetic
2Ease of operation
If wire pairs are attached to rocker arm assemblies for solenoid actuation, then magnetic latches can be powered, but wire fatigue and shorting risks increase due to rapid reciprocation
Solution Approach 1:
The patent resolves the wiring problem by changing the spatial arrangement: instead of attaching wires to the moving rocker arm assembly, the solenoid actuator is mounted on the stationary engine block or cylinder head. This separates the electrical connection point from the reciprocating motion, allowing wires to remain static and connected to the stationary actuator housing, thereby eliminating wire fatigue from rapid reciprocation
Solution Approach 2:
The actuator housing serves as an intermediary between the stationary electrical system and the moving magnetic latch. The solenoid is mounted in the actuator housing which remains stationary, while the magnetic latch is attached to the rocker arm assembly. This intermediary structure allows the electrical components to stay fixed while still controlling the moving latch mechanism
3Volume of moving object
If actuator is mounted on rocker arm assembly, then compact design is achieved, but wire fatigue risk increases from rapid reciprocation
Solution Approach 1:
The system is segmented into two separate functional units: the magnetic latch mechanism attached to the rocker arm assembly, and the solenoid actuator mounted separately on the stationary engine block. This segmentation allows the actuator housing to remain stationary while the latch follows the rocker arm motion, resolving the conflict between compactness and wire reliability
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 reduces system complexity and oil demand, enhances reliability by minimizing wire fatigue, and allows for more efficient valvetrain operation with reduced equipment costs.
Implementation Method 1
The actuator is operative to cause the latch pin to actuate or maintain a latch pin position through a magnetic field that crosses an air gap between the actuator and the magnetic latch
Implementation Method 2
An actuator for the magnetic latch includes a solenoid and is operative to cause the latch pin to translate between the first and second positions
Implementation Method 3
In some others of these teachings, a permanent magnet generates the magnetic field
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An internal combustion engine includes a valvetrain having a rocker arm assembly including a rocker arm to which a magnetic latch is mounted. An actuator for the latch is mounted off the rocker arm. The actuator may be mounted in a position that is fixed with respect to the cylinder head of the engine. Mounting off the rocker arm allows wires for the solenoid to be static. The actuator may be operative to cause the latch pin to actuate or to maintain the latch pin position through a magnetic field that crosses an air gap between the actuator and the magnetic latch. That field may be generated by a solenoid or a permanent magnet. The actuator and the latch may cooperate to form a sliding magnetic joint that keeps a magnetic circuit spanning between the latch and the actuator closed throughout the rocker arm's range of motion.