Partial Piston Twisting in Internal Combustion Engines
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Solution Overview
Problem
Existing internal combustion engines with twisted crank drives face challenges in producibility and mass balance due to slanted pistons and heads, leading to increased complexity and friction, while maintaining compactness is crucial for fitting into limited spaces.
Innovation Solution
A reciprocating internal combustion engine design with a parallel cylinder arrangement and offset crank drive, where every other cylinder is twisted, allowing for reduced engine length by offsetting the crankshaft bearing relative to the cylinder axis, combined with axial shifting of piston pins to minimize friction and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the crank drive is offset to reduce engine length, then the engine becomes more compact, but the pistons become slanted relative to the cover surface
Solution Approach 1:
The patent applies asymmetry by offsetting the crank drive only on alternating cylinders (every other cylinder) rather than all cylinders. This creates an asymmetric configuration where some cylinders have twisted crank drives while others remain straight, allowing the engine to achieve compactness on one side while maintaining manufacturability on the other.
Solution Approach 2:
The patent segments the crank drive configuration by applying the offset twist to alternating cylinders rather than uniformly to all cylinders. This segmentation allows different parts of the engine to have different configurations, resolving the contradiction between compactness and manufacturability by localizing the twist effect.
2Loss of energy
If every cylinder is twisted to maximize fuel consumption reduction, then friction forces are reduced, but the engine length reduction potential is not fully utilized
Solution Approach 1:
The patent applies partial action by twisting only every other cylinder instead of all cylinders. This partial twisting achieves a balance between reducing friction (and thus fuel consumption) and maintaining sufficient engine length reduction, avoiding the excessive action of twisting all cylinders which would not provide additional length benefits.
Solution Approach 2:
The patent applies local quality by giving different configurations to different cylinders - alternating between twisted and straight crank drives. This allows the engine to optimize friction reduction in specific cylinders while maintaining overall compactness through the alternating pattern.
3Ease of manufacture
If the cylinder distance is increased to improve producibility, then manufacturing becomes easier, but the total engine length increases
Solution Approach 1:
The asymmetric offset configuration allows the engine to maintain standard cylinder distances for manufacturability while achieving length reduction through the lateral offset of alternating cylinders. The asymmetry enables the engine to fit into compact spaces without requiring increased cylinder spacing.
Data Source
AI summary
A reciprocating internal combustion engine having a line of cylinders arranged in parallel which are joined via connecting rods and pistons by means of a crank drive that is jointly mounted in a crankshaft bearing, whereby the crankshaft bearing of the crank drive can have been offset relative to the cylinder axis.