Variable Compression Eccentric Layout Without Weakening Crankshaft Housing
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Solution Overview
Problem
Conventional methods for adjusting the compression ratio in reciprocating internal combustion engines compromise the stability of the crankshaft housing and bearing walls, leading to structural weaknesses and performance deterioration.
Innovation Solution
A device with an externally toothed eccentric, an adjustment unit, and a coupling unit using parallel, radially spaced pickup shafts, which are partially or completely housed within the crankshaft housing, cheek, and counterweight, allowing for compact and stable adjustment of the compression ratio without weakening the engine's structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional methods for adjusting compression ratio are used, then the compression ratio can be varied, but the stability of the crankshaft housing and bearing walls is compromised
Solution Approach 1:
The adjustment mechanism components (coupling unit, pickup shafts, adjusting unit) are nested within the crankshaft housing structure. The first and second pickup shafts are arranged radially spaced within the housing, with the coupling unit positioned between them. This nesting allows the variable compression ratio mechanism to be integrated without requiring additional external space that would compromise housing stability or bearing wall integrity.
Solution Approach 2:
The coupling unit employs a radial arrangement of pickup shafts rather than a linear or axial configuration. The first pickup shaft and second pickup shaft are positioned at different radial locations within the crankshaft housing, allowing the adjustment mechanism to utilize the radial dimension of the housing. This dimensional approach enables compact integration while maintaining structural integrity of the bearing walls.
2Use of energy by moving object
If the adjustment mechanism is added to vary compression ratio, then fuel efficiency improves, but the device complexity increases
Solution Approach 1:
The coupling unit merges the functions of the first pickup shaft and second pickup shaft into a single integrated component structure. Both shafts are mechanically coupled to each other and to the adjusting unit through the coupling unit, consolidating multiple adjustment functions into one unified mechanism. This merging reduces the number of separate components and simplifies the overall adjustment system while maintaining the ability to vary compression ratio for improved fuel efficiency.
3Volume of moving object
If the pickup shafts are arranged radially spaced within the crankshaft housing, then the design becomes more compact, but the manufacturing precision requirements increase
Solution Approach 1:
The first pickup shaft and second pickup shaft are positioned at asymmetric radial locations within the crankshaft housing rather than at symmetric positions. This asymmetric arrangement allows optimization of the compact layout to fit within the available housing space while accommodating the specific geometric requirements of the eccentric and adjusting unit. The asymmetric positioning reduces interference with other components and allows for more practical manufacturing tolerances compared to a constrained symmetric arrangement.
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 enables reliable adjustment of the compression ratio with improved stability and performance, maintaining the strength of the crankshaft and crankshaft housing while allowing for variable compression ratios, thereby enhancing fuel efficiency and reducing emissions.
Implementation Method 1
an externally toothed eccentric, which is designed and configured to be rotatably arranged between a crankpin of a crankshaft of a crank mechanism and a connecting rod eye of a connecting rod for changing the stroke height of a piston
Implementation Method 2
an adjusting unit, which is mechanically coupled to an external toothing of the eccentric and is designed for adjusting the eccentric by rotating the eccentric
Implementation Method 3
a coupling unit, which is designed for mechanically coupling the eccentric to the adjusting unit and for this purpose comprises first and second customer shafts arranged parallel to each other, radially spaced from each other and mechanically coupled to each other
Data Source
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AI summary
The invention relates to a device (10) for varying a compression ratio of a reciprocating-piston internal combustion engine (100), having an externally toothed eccentric (3) which is designed to be arranged between a crankpin (28) of a crankshaft (20) of a crank drive (20') and a connecting-rod eye of a connecting rod (22) in rotationally movable fashion for the purposes of varying a stroke length of a piston, which is mechanically coupled to the connecting rod (22), of the reciprocating-piston internal combustion engine (100), having an adjusting unit (12) which is mechanically coupled to an external toothing (3-1) of the eccentric (3) and which is designed for adjusting the eccentric (3) by rotation of the eccentric (3), and having a coupling unit (56) which is designed for mechanically coupling the eccentric (3) to the adjusting unit (12) and which, for this purpose, is formed with first and second pick-off shafts (5, 6) which are arranged parallel to one another, radially spaced apart from one another and mechanically coupled to one another, wherein the first pick-off shaft (5) is mechanically coupled to the external toothing (3-1) of the eccentric (3) and the second pick-off shaft (6) is mechanically coupled to the adjusting unit (12), and wherein the coupling unit (56) and in particular the first and second pick-off shafts (5, 6), the eccentric (3) and/or the adjusting unit (12) are designed for being partially or entirely arranged (a) in the interior of the crankshaft housing of the crankshaft (20), (b) within a structural space of a web (23) of the crankshaft (20), and/or (c) within a structural space of a counterweight (24).