Shuttle-Bearing Piston Assembly for Lower TDC Acceleration
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Solution Overview
Problem
Conventional internal combustion engines face issues with high piston acceleration at top dead center (TDC) leading to reduced dwell time, increased component stress, and inefficiencies, as well as lubrication challenges due to the crankshaft and con-rod arrangement, which results in high wear rates and environmental concerns.
Innovation Solution
A piston arrangement using a shuttle bearing with a non-planar bearing surface to convert reciprocating motion to rotary motion, allowing reduced acceleration spikes and increased dwell time, and a separate supercharging chamber for efficient lubrication, eliminating the need for a total loss lubrication system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional crankshaft and con rod arrangement is used to convert linear piston motion to rotary motion, then the engine structure is simple and reliable, but maximum piston acceleration occurs at TDC leading to reduced dwell time, increased component stress, and decreased efficiency
Solution Approach 1:
The patent employs a cam mechanism with curved profiles instead of straight-line crankshaft motion. The cam follower tracks the curved cam surface, which geometrically controls the piston acceleration profile to reduce peak acceleration at TDC and increase dwell time, directly improving combustion efficiency while maintaining structural reliability
Solution Approach 2:
The invention changes the motion parameters by using a cam mechanism with specific profile geometry to alter the piston acceleration characteristics. The cam profile is designed to modify the velocity and acceleration parameters throughout the cycle, specifically reducing maximum acceleration at TDC while maintaining adequate dwell time for combustion
2Device complexity
If a conventional crankshaft and con rod arrangement is used, then the engine structure is straightforward, but high piston acceleration at TDC inflicts severe stresses on engine components increasing design requirements and component weight
Solution Approach 1:
The cam mechanism with its curved profile inherently distributes forces more evenly compared to the sharp acceleration peaks of a crankshaft. The gradual curvature of the cam surface reduces impulsive loading on components, allowing for lighter component designs while maintaining adequate strength
3Device complexity
If a conventional crankshaft and con rod arrangement is used housed within a crank case, then the engine structure is compact, but the total loss lubrication system is expensive to run and damaging to the environment
Solution Approach 1:
The patent extracts the power transfer mechanism from the conventional crank case housing and implements a separate cam mechanism. This extraction allows for a distinct lubrication system that does not require total loss oil consumption, eliminating the environmental harm of oil in exhaust gases while maintaining structural compactness
Solution Approach 2:
The cam mechanism design allows for more efficient lubrication where oil can be reused in a closed loop system rather than being continuously consumed and expelled. The mechanism serves itself with reduced lubrication requirements, eliminating the need for continuous oil replacement and environmental discharge
4Productivity
If alternative coupling arrangements such as Pattakon Greco, Bourke, Revetec or Wankel engines are used to reduce maximum piston acceleration, then TDC dwell time is increased, but line contact patch transmission results in high stress concentrations and increased wear rates
Solution Approach 1:
The cam mechanism uses a curved profile that distributes contact forces over a broader area compared to line contact arrangements. The follower rides on the curved cam surface, creating a more favorable stress distribution that reduces wear rates while maintaining the increased TDC dwell time benefit
5Productivity
If alternative coupling arrangements with complex cam shapes are used, then piston acceleration is reduced, but the machining of high-precision cam shapes is difficult and expensive to manufacture
Solution Approach 1:
The cam profile uses a standardized curved geometry that can be manufactured using conventional machining processes. The curvature is designed to achieve the desired motion characteristics while remaining manufacturable with standard tooling and techniques, avoiding the need for complex, high-precision custom cam shapes
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
This solution reduces wear rates, minimizes component weight, increases combustion efficiency, and allows for optimized counterbalancing, resulting in a more reliable, efficient, and environmentally friendly engine with reduced maintenance costs and improved performance.
Implementation Method 1
the shuttle bearing coupled to the piston via a non-planar bearing surface thereby allowing rotation of the shuttle bearing
Data Source
Figure 1
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Figure 2b
AI summary
A piston arrangement comprising: a piston, a first chamber, a second chamber and a power transfer assembly; wherein the piston comprises a first head movable within the first chamber and a second head movable within the second chamber; wherein, in operation, the piston follows a linear path in reciprocating motion along a first axis; wherein the power transfer assembly comprises a shaft rotatably coupled to a shuttle bearing and arranged to convert the reciprocating motion of the piston to rotary motion of the shaft; wherein the shuttle bearing moves relative to the piston in reciprocating motion along a second axis substantially transverse to the first axis; and wherein the shuttle bearing is coupled to the piston via a non-planar bearing surface thereby allowing rotation of the shuttle bearing.