Asymmetric Latch Pin Assembly for Rocker Arm Orientation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The precise orientation of latch pins in rocker arms for internal combustion engines is challenging due to manufacturing costs and the need for high precision, which complicates the selective deactivation and activation of rocker arms.
Innovation Solution
A latch pin assembly with a pin body having a non-circular cross-section and a retainer with a male engagement portion, both with non-circular cross-sections, is used, along with a biasing mechanism to facilitate easy engagement and disengagement, allowing the rocker arm to be activated or deactivated by changing the oil pressure, thus simplifying the assembly and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat latch pin surface is used for engagement, then the rocker arm can be selectively deactivated, but the latch pin requires precise rotational orientation which increases manufacturing complexity and cost
Solution Approach 1:
The latch pin and retainer are designed with asymmetric non-circular cross-sections that provide unique engagement geometries. The retainer has a male engagement portion with a specific asymmetric shape that mates with a corresponding asymmetric female portion in the latch pin, eliminating the need for precise rotational orientation while ensuring proper engagement for selective deactivation
2Reliability
If a flat latch pin surface is used, then the rocker arm can be deactivated, but the assembly process becomes complex due to orientation requirements
Solution Approach 1:
The asymmetric non-circular cross-sections of the latch pin and retainer provide self-aligning engagement features that guide proper positioning during assembly, eliminating the need for complex orientation procedures and reducing assembly complexity while maintaining deactivation reliability
3Manufacturing precision
If precise orientation of latch pin is required, then proper engagement is achieved, but manufacturing costs increase
Solution Approach 1:
The asymmetric engagement surfaces of the latch pin and retainer provide inherent alignment features that ensure proper engagement without requiring high-precision manufacturing tolerances, thereby reducing manufacturing costs while maintaining engagement precision
Data Source
AI summary
A rocker arm for engaging a cam in a valve actuation arrangement includes a latch pin assembly having includes a latch pin, retainer, and biasing mechanism. The latch pin has a pin body with a head and a tail at the second end; the body defining an open volume; the tail having an open mouth in communication with the open volume of the body; and the open volume having a non-circular cross-section. The retainer has a male engagement portion and an outer portion. The male engagement portion is within the open volume of the body through the open mouth. The male engagement portion has a non-circular cross section. The outer portion is non-removably secured to an outer arm of the rocker arm. The biasing mechanism is oriented in the open volume of the body and between and against the latch pin and the retainer.