Expanding-Ring Piston Support for Eccentric Oscillation Damping
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Solution Overview
Problem
Existing supporting arrangements for eccentric members in adjusting mechanisms of internal combustion engines experience oscillations due to increasing gas and mass forces at high engine rotational speeds, leading to 'blow-by' phenomena and increased oscillation amplitudes.
Innovation Solution
A multi-piece piston design with an expanding ring between its lower and upper parts, which applies a friction force on the supporting cylinder's inner wall when pressure exceeds a defined threshold, creating an additional force path to reduce oscillation tendencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-piece piston design is used, then the structure is simple, but oscillations occur at high engine speeds due to insufficient friction force
Solution Approach 1:
The piston is divided into two separate parts: a piston upper part and a piston lower part. Between these two parts, an expanding ring is positioned that can spread laterally when pressure increases, creating additional friction force against the supporting cylinder wall. This segmentation allows the system to maintain simplicity while adding the oscillation-dampening function through the expandable ring mechanism.
2Stability of the object's composition
If friction force is increased to reduce oscillations, then stability improves, but the risk of 'blow-by' phenomena increases due to pressure buildup
Solution Approach 1:
The friction force is made dynamic rather than static. The expanding ring remains compressed during normal operation, allowing smooth piston movement. When oscillations occur and pressure increases, the ring automatically expands to increase friction force, damping the oscillations. This dynamic adjustment prevents the need for continuously high friction that would cause blow-by phenomena.
3Stability of the object's composition
If a multi-piece piston with expanding ring is used, then oscillation resistance improves, but device complexity increases
Solution Approach 1:
The expanding ring is nested between the piston upper part and piston lower part, fitting within the existing piston structure. This nesting approach adds the oscillation-dampening functionality without requiring a completely redesigned piston system, thereby limiting the increase in overall device complexity while achieving the stability improvement.
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 additional friction force stabilizes the supporting arrangement by opening a parallel force path, effectively reducing oscillations and preventing 'blow-by' phenomena, even at high engine speeds.
Implementation Method 1
A friction force can be applied by the expanding ring on an inner wall region of the supporting cylinder
Data Source
AI summary
A support for an eccentric of an adjusting arrangement of a connecting rod has a piston rod (18) guided by a piston (20). A seal (24) is connected to the piston (20) in a supporting cylinder (12, 14) in the connecting rod (2) and has a longitudinal axis (16). The piston (20) encloses a chamber (22) with the supporting cylinder (12, 14). The piston (20) has a lower part (30) arranged on an upper part (28) for movement along the axis (17) of the supporting cylinder (12, 14). An expanding ring (40) between the upper and lower parts (28, 30) interacts with faces (42, 44) of the lower part (30). The upper part (28) spreads the expanding ring (40) as the spacing between the faces (42, 44) is reduced, and the expanding ring (40) applies a friction force FR on an inner wall (46) of the supporting cylinder.