Bidirectional Latch Pin Assembly for Switchable Rocker Arm
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Solution Overview
Problem
Existing rocker arm mechanisms with latch pins struggle to switch stably with a low part count in a compact design, limiting their efficiency in valve actuation.
Innovation Solution
A bidirectional latch pin assembly with a stepped latch pin configured to switch among three positions, utilizing a combination of hydraulic and electromechanical actuation systems, including a spring for stable positioning and actuation assemblies to move the latch pin between these positions, ensuring stable operation with a low part count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a latch pin mechanism is designed to switch among multiple positions, then the valve actuation control is improved, but the device complexity increases
Solution Approach 1:
The latch pin is segmented into multiple sections with different diameters (first section, second section, third section) that correspond to different valve actuation modes. This segmentation allows the single latch pin to provide multiple functions without requiring separate mechanisms for each position, thus improving versatility while controlling complexity.
Solution Approach 2:
The latch pin assembly is designed as a multi-functional component that can simultaneously provide different valve lift characteristics (first, second, and third valve lift characteristics) through its varying diameter sections. This universal design allows one component to perform multiple functions that would traditionally require separate mechanisms.
2Adaptability or versatility
If the latch pin is extended further to engage different positions, then the switching capability is improved, but the length of the moving object increases
Solution Approach 1:
The latch pin is divided into segments of different lengths and diameters. The first section has a first length and the second section has a second length, allowing the pin to engage at different positions along the rocker arm without requiring uniform extension throughout its entire length. This segmented approach enables switching capability while minimizing overall length.
3Reliability
If a spring is added to ensure stable positioning, then the reliability is improved, but the quantity of parts increases
Solution Approach 1:
The spring is integrated into the existing latch pin assembly structure, combining the spring function with the latch pin mechanism. The spring is positioned to interact with the latch pin in a way that provides stable positioning while using the same spatial envelope and material resources as the existing components, thus improving reliability without proportionally increasing part count.
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 stable switching among three positions with a low part count, facilitating efficient valve actuation and supporting variable valve lift modes, such as early or late valve opening, while maintaining lightweight and efficient use of internal space.
Implementation Method 1
A spring can be biased against the guide and can be configured to bias the latch pin to a first position extending the first step out of the latch port
Implementation Method 2
A hydraulic pressure supply can be connected to the latch port to supply fluid actuation force to move the latch pin in a first direction
Data Source
AI summary
A bidirectional latch pin assembly can comprise a housing portion comprising a latch port. A latch pin in the latch port can comprise a stepped nose extending from a body portion. The stepped nose can comprise a first step and a second step. A spring can be biased against a guide mounted in the latch port and the spring can be configured to bias the latch pin to a first position extending the first step out of the latch port. A first actuation assembly can be configured to move the latch pin to a second position extending the first step and the second step out of the latch port. A second actuation assembly can be configured to move the latch pin to a third position pulling the first step and the second step into the latch port. A switchable rocker arm and a valvetrain assembly can be formed therewith.