Lock-up Device Float Member Vibration Suppression
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Solution Overview
Problem
Widening the torsion angle of the damper in lock-up devices to efficiently absorb and damp torque fluctuations leads to increased potential for normal mode vibrations and unpleasant vibrations at high engine speeds, which can result in resonance issues and vibration noise.
Innovation Solution
A lock-up device design that includes an input rotation member, an output rotation member, plural first elastic members, and a float member, where the first elastic members are arranged in series with varying free lengths to adjust their rigidity, allowing for effective torque transmission and vibration damping while maintaining the vibration level within an allowable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the torsion angle of the damper is widened by arranging torsion springs in series, then torque fluctuation absorption is improved, but normal mode vibrations occur at high engine speeds causing unpleasant vibrations and noise
Solution Approach 1:
The patent applies local quality by making the first and second torsion springs have different free lengths and different rigidities. Specifically, the first torsion spring has a longer free length and lower rigidity, while the second torsion spring has a shorter free length and higher rigidity. This non-uniform distribution of elastic properties allows the system to maintain good torque fluctuation absorption while suppressing normal mode vibrations at high speeds.
Solution Approach 2:
The patent employs asymmetry by configuring the torsion springs with unequal free lengths and unequal rigidities. The first torsion spring and second torsion spring are deliberately made asymmetric in their mechanical properties, which disrupts the symmetric vibration modes that cause normal mode vibrations and associated noise at high engine speeds.
2Shape
If two outer peripheral side torsion springs are coupled in series via a float member, then the torsion angle can be designed wider, but the resonance speed of the float member occurs in the normal speed range causing vibration
Solution Approach 1:
The patent applies parameter changes by modifying the free lengths and rigidities of the torsion springs. The first torsion spring is designed with a longer free length and lower rigidity, while the second torsion spring has a shorter free length and higher rigidity. These parameter adjustments ensure that the resonance speed of the float member is shifted to a higher speed range, outside the normal operating speed range of the engine.
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 design effectively sets the resonance speed of the float member to a higher speed, reducing the vibration level and preventing resonance issues within the normal operating range, thus maintaining the vibration level within acceptable limits.
Implementation Method 1
The plural first elastic members are compressed in a rotational direction by the relative rotation of the input rotation member and the output rotation member
Implementation Method 2
absorb and damp torque fluctuations input from the engine
Implementation Method 3
The float member is placed in such a way as to be rotatable relative to the input rotation member in order to cause at least two of the first elastic members among the plural first elastic members to act in series in a circumferential direction
Data Source
AI summary
A lock-up device for a fluid coupling suppresses vibration caused by coil springs. The lock-up device includes an input rotation member, an output rotation member, a plurality of sets of first elastic members, and a float member. The plurality of sets of first elastic members are compressed in a rotational direction by the relative rotation between the input rotation member and the output rotation member. The float member float member is configured to restrict movement of the plurality of sets of first elastic members in a radial direction.