Sintered Planetary Gears for Direct Crank Drive
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Solution Overview
Problem
The classical crank mechanism in internal combustion engines and compressors faces issues such as high frictional forces, weight-related inefficiencies, and balance difficulties due to its structural limitations, which hinder mechanical efficiency and require additional components like counter-rotating shafts and excessive oil usage, leading to pollution and space constraints.
Innovation Solution
The use of steel sintering technology to produce monolithic or multi-component planetary gears with excellent tribological properties, reducing production costs and complexity, allowing for direct mounting on the rotor without bushings and eliminating the need for a gudgeon pin, thereby simplifying the mechanism and enhancing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a classical crank mechanism is used to convert rectilinear reciprocating motion to rotary motion, then the mechanism can perform the required motion conversion, but high frictional forces occur between the piston side wall and cylinder wall due to the obliquity of the piston rod
Solution Approach 1:
The invention extracts and eliminates the piston rod (connecting rod) from the classical crank mechanism. By directly connecting the piston to the crank pin, the obliquity-induced frictional forces between the piston side wall and cylinder wall are removed, significantly reducing frictional losses while maintaining the motion conversion function
Solution Approach 2:
The invention merges the piston and connecting rod into a single integrated component. The piston directly connects to the crank pin without an intermediate piston rod, simplifying the mechanism structure and eliminating the harmful obliquity effects while preserving the essential motion conversion capability
2Reliability
If the piston rod is made sufficiently long to reduce the overturning action and risk of seizure, then the reliability improves, but the weight and inertial forces increase, reducing efficiency
Solution Approach 1:
The invention completely removes the piston rod from the mechanism. By directly connecting the piston to the crank pin, the overturning action is eliminated at its source, achieving high reliability without the weight and inertial penalties of a long piston rod
Solution Approach 2:
The invention performs preliminary design optimization by directly integrating the piston connection to the crank pin, preventing the development of overturning moments before they can cause reliability issues, thereby eliminating the need for heavy-duty long piston rods
3Productivity
If the stroke value is increased to allow smaller cylinder bores and larger strokes for better cooling and efficiency, then the thermal efficiency improves, but the classical crank mechanism with oscillating connecting rod prevents exceeding certain stroke limits due to space constraints
Solution Approach 1:
By removing the oscillating connecting rod from the mechanism, the invention eliminates the spatial constraints that limited stroke length. This allows the design of engines with larger stroke-to-bore ratios, improving thermal efficiency and cooling effectiveness without increasing overall engine dimensions
Solution Approach 2:
The invention changes the kinematic dimensioning of the mechanism by eliminating the intermediate connecting rod, allowing the piston to achieve greater displacement along the cylinder axis without increasing the perpendicular dimensions, thus enabling larger strokes within compact engine envelopes
4Device complexity
If the piston rod is eliminated and the piston is directly connected to the crank pin, then the frictional losses and structural complexity are reduced, but the piston must withstand both gas pressure and bending moments simultaneously
Solution Approach 1:
The invention applies local quality enhancement by concentrating the structural reinforcement at the piston-crank pin connection point. The piston is designed with localized strengthening at the crank pin mounting area to handle the combined gas pressure and bending moments, while maintaining lighter overall piston weight and simpler mechanism structure
Solution Approach 2:
By merging the piston and crank pin connection into a direct integral structure, the invention eliminates the weak joint of the piston rod connection. The unified structure allows for optimized stress distribution and localized reinforcement, simultaneously reducing mechanism complexity and enhancing strength where needed
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 approach reduces frictional losses, weight, and structural complexity, enabling more efficient energy conversion and reduced pollution by allowing smaller cylinder bores and larger strokes, while maintaining mechanical efficiency and reliability.
Implementation Method 1
The use of steel sintering technology to produce monolithic or multi-component planetary gears with excellent tribological properties
Data Source
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AI summary
By producing a planet (4) in accordance with the technology of sintered materials it becomes possible to solve the problems of structural complexity/space, because the planet (4) realised in this way can be directly mounted on the rotor of the driving shaft without the interposition of bushings, by relying on the very good tribological properties of sinter ed materials; moreover, this material, by virtue of its texture composed of micro-granules, has excellent properties of fatigue strength and yield/breaking tensions very near to the corresponding parameters of a compact material.