Roller Valve Lifter Oil Feed and Bushing Design
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Solution Overview
Problem
High-performance engine roller cam followers with needle or pin roller bearings are prone to premature failure due to high valve spring loads and rpm levels, as the needle rollers are the weakest link and can experience rapid erosion, leading to radial bearing clearance increases and catastrophic failures.
Innovation Solution
A roller valve lifter with a cam follower bearing featuring a press-fit inner sleeve bushing and oil feed holes in the legs to channel lubricating oil directly to the bearing interface, reducing the risk of seizure and wear, and incorporating a key device or vertical guide bar for proper orientation and increased oil delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If needle or pin roller bearings are used in roller cam followers, then the device complexity is reduced, but the reliability deteriorates due to premature failure under high valve spring loads and rpm levels
Solution Approach 1:
The patent changes the bearing type parameter from needle/pin roller bearings to plane bearings with bushings, fundamentally altering the bearing mechanism to eliminate the weakest link (needle rollers) while maintaining structural simplicity. This parameter change enables the bearing to withstand high valve spring loads and rpm levels without premature failure.
2Ease of operation
If a V-shaped lubrication oil passage is formed in the pin or axle, then the ease of operation is improved by delivering oil to the bearing interface, but the strength deteriorates due to stress risers at the intersection of drilled holes
Solution Approach 1:
The patent extracts the lubrication passage from the pin or axle structure and relocates it to the bushing component. The bushing includes oil feed holes that receive lubricant from an engine oil pressure source, separating the lubrication function from the load-bearing pin structure. This eliminates stress risers in the pin while ensuring adequate lubrication through the bushing's integrated oil delivery system.
3Manufacturing precision
If traditional needle roller bearings are used, then the manufacturing precision requirements are reduced, but the durability deteriorates due to rapid erosion of needle rollers under high load conditions
Solution Approach 1:
The patent employs composite construction with a bushing (inner sleeve) press-fitted into the plane bearing. The bushing can be made from materials optimized for lubrication and wear resistance, while the plane bearing provides structural support. This composite approach enhances durability under high load conditions without requiring extremely tight manufacturing tolerances, as the bushing-material interface provides inherent lubrication and wear protection.
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 provides reliable performance with reduced risk of cam follower bearing failure, even under extreme conditions, by ensuring consistent lubrication and proper alignment, thereby enhancing the durability and reliability of high-speed engine components.
Implementation Method 1
A roller valve lifter may have a body with two opposed subtending spaced apart legs. A cam follower roller bearing having a press fit inner sleeve bushing may be rotatably mounted on the pin. Each of the legs may have an oil feed hole that traverses from an exterior surface to an interior surface adjacent to the inner sleeve bushing.
Data Source
AI summary
The present invention may be used for vehicle engines having bores in which roller valve lifters reciprocate. A roller valve lifter may have a body with two opposed subtending spaced apart legs. A cam follower roller bearing having a press fit inner sleeve bushing may be rotatably mounted on the pin. Each of the legs may have an oil feed hole that traverses from an exterior surface to an interior surface adjacent to the inner sleeve bushing. The body in an upper portion may have a key device or an attached vertical guide bar to maintain proper orientation of the roller valve lifter to a cam lobe.