Switchable Rocker Arm With Lost Motion Spring Locking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rocker arms for internal combustion engines lack efficient mechanisms to switch between coupled and decoupled states for valve lift adjustment, affecting fuel efficiency and compactness in engine design.
Innovation Solution
A rocker arm design featuring an inner arm that selectively pivots relative to an outer arm, utilizing lost motion springs and a lock pin mechanism to control the pivot direction, with roller retainers to ground the springs, allowing for compact assembly and easy switching between valve lift modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a lock pin mechanism is used to switch between coupled and decoupled states, then valve lift adjustment capability is improved, but device complexity increases
Solution Approach 1:
The lost motion springs automatically engage and disengage the lock pin with the groove on the inner arm through relative pivoting motion, eliminating the need for external actuation mechanisms. The springs self-regulate the coupling state based on the pivot angle, reducing overall system complexity while maintaining switching capability.
Solution Approach 2:
The lock pin transition from engaged to disengaged state is dynamic rather than static, allowing smooth transitions between coupled and decoupled states. The spring-loaded mechanism enables the lock pin to automatically follow the groove's path during pivoting, creating a flexible switching system that adapts to motion requirements.
2Volume of moving object
If the inner arm is allowed to pivot relative to the outer arm, then compactness is improved, but stability of composition worsens
Solution Approach 1:
The rocker arm is divided into separate inner arm and outer arm components that can pivot relative to each other, allowing compact folding when decoupled. The segmentation enables the arms to occupy less space when not in use while maintaining structural integrity when coupled through the lock pin engagement.
3Ease of manufacture
If roller retainers are used to ground lost motion springs, then ease of manufacture is improved, but device complexity increases
Solution Approach 1:
The roller retainer combines multiple functions into a single component: it retains the roller on the roller shaft, provides a mounting surface for grounding the lost motion spring, and maintains proper positioning of the spring tang. This merging reduces the total number of parts needed while simplifying the manufacturing process.
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
Enables efficient switching between valve lift modes, improving fuel efficiency and compactness by allowing the inner arm to pivot relative to the outer arm, enhancing the rocker arm's ability to adjust valve lift and reducing assembly complexity.
Implementation Method 1
a first lost motion spring having a first lost motion spring outer arm tang grounded to the outer arm and a first lost motion spring inner arm tang grounded to the inner arm, the first lost motion spring biasing the inner arm to pivot relative to the outer arm
Data Source
AI summary
A rocker arm includes an outer arm having a first wall and a second wall and an inner arm which selectively pivots relative to the outer arm about a pivot shaft axis based on positioning of a lock pin. A lost motion spring includes an outer arm tang grounded to the outer arm and an inner arm tang grounded to the inner arm. A roller shaft is supported by the inner arm and extends toward the first wall. The roller shaft carries a roller which follows a camshaft. A roller retainer is carried by the roller shaft and is located between the roller and the first wall and includes a surface with which the inner arm tang is engaged to ground the lost motion spring to the inner arm through the roller shaft.