Valve Lifter Pin Housing Contoured Surface
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Solution Overview
Problem
Prior art hydraulic valve lifters suffer from damage to the central region of the cam-following roller due to collisions with the pin housing during latch ejection, leading to wear and potential costly repairs to the engine's camshaft lobe.
Innovation Solution
A reconfigured dished or chamfered surface on the pin housing prevents contact with the central region of the roller, redirecting impact to the margins and avoiding damage to the cam lobe by ensuring any collision occurs outside the central contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pin housing uses a conventional flat bottom surface, then manufacturing is simple, but the roller central region suffers damage from latch ejection collisions
Solution Approach 1:
The patent applies curvature by replacing the flat bottom surface of the pin housing with a contoured surface that has a radius of curvature. This curved surface redirects the collision force from latch ejection away from the roller's central region, preventing damage while maintaining manufacturing feasibility through standard forming processes.
Solution Approach 2:
The patent applies local quality by creating a specific contoured surface geometry at the critical interaction zone between the pin housing and roller. The contoured surface is localized to the bottom of the pin housing where collision occurs, providing targeted protection to the roller's central region without requiring modification of the entire pin housing structure.
2Reliability
If the roller central region is protected from damage, then camshaft lobe integrity is maintained, but device complexity increases due to contoured surface requirements
Solution Approach 1:
The contoured surface with its radius of curvature provides a straightforward geometric solution that protects the roller central region. This curved surface design is relatively simple to manufacture using standard forming or machining processes, avoiding the need for complex multi-step manufacturing while achieving the reliability goal.
Solution Approach 2:
The patent changes the geometric parameters of the pin housing bottom surface by introducing a specific radius of curvature. This parameter modification transforms the flat surface into a contoured surface that redirects collision forces, protecting the roller without requiring complex structural changes or multiple components.
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 effectively prevents damage to the central region of the roller and the associated camshaft lobe, reducing wear and maintenance costs by ensuring that any impact occurs at the margins of the roller's surface, thus maintaining the integrity of the camshaft lobe.
Implementation Method 1
two opposed locking pins urged outwards of the pin housing by a pin-locking spring disposed in compression therebetween
Implementation Method 2
application of hydraulic fluid such as engine oil to the outer ends of the pins at a pressure sufficient to over come the force of the pin-locking spring
Implementation Method 3
mutual actuation by rotary motion of the cam lobe to produce reciprocal motion of an engine pushrod
Data Source
AI summary
A valve-deactivation hydraulic valve lifter including a recessed face on the pin housing for making contact with the a crowned surface region of a roller follower. The lifter includes a pin housing that is slidably disposed within an axial bore in a lifter body. Pins for variably locking the pin housing to the lifter body may be disengaged to place the lifter in lost-motion mode by application of engine oil to the outer ends of the pins. A surface of the pin housing, preferably configured as a dished surface, is formed on the bottom end face of the pin housing that approaches the cam-following lifter roller for making contact with the roller follower so as to avoid contacting the roller follower's crowned surface region.