Switchable Lever Lash Adjustment Mechanism
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Solution Overview
Problem
Switchable levers in internal combustion engine valve trains face challenges in efficiently adjusting lash to accommodate varying operating conditions and limited packaging space, particularly when using electric actuators instead of hydraulic fluid.
Innovation Solution
A lash adjustable coupling assembly with an inner rod and outer cylinder, featuring internal and external threads, and an optional lash adjustment spring, allows for selective locking and unlocking of the inner and outer levers, enabling adjustable lash settings to optimize valve lift modes and accommodate thermal growth or wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydraulic fluid is used to actuate the coupling assembly, then the system can achieve valve lift switching, but hydraulic fluid galleries must be arranged throughout the engine increasing packaging complexity
Solution Approach 1:
The patent replaces the hydraulic fluid actuation system with an electric actuator that directly moves the inner rod. This eliminates the need for hydraulic fluid galleries throughout the engine while maintaining the valve lift switching capability. The electric actuator uses electrical signals to control the coupling assembly, simplifying the overall system architecture.
Solution Approach 2:
The patent extracts and removes the hydraulic fluid delivery system from the valve train actuation mechanism. By taking out the hydraulic fluid galleries and reservoir infrastructure, the design eliminates complex routing requirements while preserving the essential function of switching between different valve lift modes through electric actuation.
2Adaptability or versatility
If hydraulic fluid actuation is used, then valve lift switching is achieved, but actuation time is slower compared to electric actuators
Solution Approach 1:
The patent substitutes the hydraulic fluid pressure system with an electric actuator that provides direct mechanical movement. Electric actuators respond instantaneously to control signals, eliminating the fluid compression and pressure build-up delays inherent in hydraulic systems, thereby achieving faster actuation times for valve lift switching.
3Device complexity
If lash adjustment is not provided, then the structure is simpler, but the system cannot accommodate thermal growth or wear
Solution Approach 1:
The patent incorporates an adjustable lash mechanism that allows dynamic modification of the coupling between inner and outer levers. The adjustable element enables the system to adapt to changing conditions such as thermal expansion and component wear, maintaining proper clearance and ensuring reliable operation throughout the engine's service life.
4Volume of moving object
If electric actuator is used, then packaging space is reduced, but the system requires new actuation mechanisms
Solution Approach 1:
The patent merges the electric actuator directly with the coupling assembly, integrating the actuation mechanism into the existing lever structure. This consolidation eliminates the need for separate hydraulic infrastructure while reducing overall packaging space, as the electric actuator can be compactly mounted within or adjacent to the coupling assembly.
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
The solution enables efficient adjustment of lash settings to maintain optimal valve operation across varying conditions, reducing the need for frequent maintenance and enhancing the reliability and efficiency of the switchable lever system within the constrained packaging of an IC engine.
Implementation Method 1
A lash adjustment spring, optionally located between a first end of the inner rod and a first end of the outer cylinder, can be arranged to outwardly urge the inner rod with respect to the outer cylinder
Implementation Method 2
The outer cylinder can be formed with internal threads and the inner rod can be formed with external threads
Data Source
AI summary
A switchable lever is provided that includes an outer lever, an inner lever pivotably mounted to the outer lever, and a lash adjustable coupling assembly capable of selectively locking the inner lever to the outer lever. The lash adjustable coupling assembly includes an inner rod and an outer cylinder configured to adjustably receive the inner rod. The inner rod can be formed with external threads and the outer cylinder can be formed with internal threads. A lash adjustment spring can be arranged to outwardly urge the inner rod with respect to the outer rod to adjust lash within a switchable lever system.