Switchable Rocker Arm Segmentation for Tight Engine Packaging
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Solution Overview
Problem
Packaging switchable rocker arms in the tight spaces of combustion machines is problematic, and there is a need for lightweight designs that facilitate easy integration and installation.
Innovation Solution
A switchable rocker arm design featuring a main body with a forked cam end, a second body with pivot and latch bores, a latch assembly, and a lost motion spring mounted over a transfer portion, along with a hydraulic feed system to control piston movement, allowing for variable valve actuation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switchable functionality is integrated into the rocker arm, then variable valve actuation capability is improved, but device complexity increases
Solution Approach 1:
The rocker arm is divided into a main body and a separate second body that can pivot relative to each other. The second body contains the latch assembly and piston assembly, while the main body contains the valve actuation components. This segmentation allows the switchable functionality to be added without completely redesigning the entire rocker arm structure.
Solution Approach 2:
The latch assembly and piston assembly are nested within the second body, which itself is integrated with the main rocker arm body. The transfer portion of the second body transfers motion from the main body to the latch mechanism, creating a compact nested structure that adds functionality without proportionally increasing overall size.
2Weight of moving object
If lightweight design is implemented, then overall machine weight is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The pivot portion is designed with specific local features including bearing surfaces and alignment features that ensure precise positioning. The second body includes a pivot portion with bearing surfaces that mate with corresponding features in the main body, providing precise alignment while using lightweight materials and hollow construction in non-critical areas.
Solution Approach 2:
The pivot portion is pre-configured with bearing surfaces and alignment features during manufacturing, ensuring that when the second body is assembled to the main body, the pivot alignment is already optimized. This preliminary preparation of the pivot portion reduces the need for post-assembly adjustments and maintains precision while using lightweight construction.
3Ease of manufacture
If integrated manufacturing is used, then ease of installation is improved, but device complexity increases
Solution Approach 1:
The rocker arm is provided as a complete integrated assembly with the main body, second body, latch assembly, and piston assembly pre-configured together. This segmented design allows the entire switchable rocker arm to be installed as a single unit, replacing the conventional rocker arm without requiring complex on-site assembly procedures.
Solution Approach 2:
The second body is designed to perform multiple functions: it houses the latch assembly, contains the piston assembly, provides the pivot connection to the main body, and includes the transfer portion for motion transmission. This multi-functionality reduces the number of separate components needed, simplifying installation while maintaining the complex switchable functionality.
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 integration and lightweight packaging of switchable rocker arms, facilitating easy installation and enabling variable valve actuation techniques such as cylinder deactivation and enhanced valve lift events.
Implementation Method 1
A lost motion spring can be mounted over the transfer portion. The lost motion spring can have its center of inertia balanced over the transfer portion.
Implementation Method 2
A hydraulic feed in the main body can be configured to supply hydraulic fluid to the first piston bore and to the second piston bore.
Data Source
AI summary
A switchable rocker arm can comprise a main body configured to rotate around a rocker shaft. The main body can comprise a valve end and a cam end. A second body can comprise a cam-receiving transfer portion and a latch bore through the transfer portion. The cam-receiving transfer portion can include a bearing axle and a roller bearing. A latch assembly including a first latch and a second latch can be mounted in the latch bore.