Planetary Torsional Vibration Damper With Variable Gear Backlash
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Solution Overview
Problem
Existing torsional vibration dampers experience reduced vibration damping performance at high engine speeds due to increased inertia torque, which can lead to ineffective suppression of torsional vibrations.
Innovation Solution
A torsional vibration damper with a planetary gear unit that includes a sun gear, ring gear, and carrier, where pinion gears are oscillated within specific ranges based on torque levels, and backlash between gears is adjusted to reduce torque transmission efficiency at high speeds, ensuring effective vibration suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inertia torque of the ring gear is increased to suppress torsional vibrations, then vibration damping performance is improved at low speeds, but at high speeds the inertia torque becomes excessive and acts as a vibratory force that reduces damping performance
Solution Approach 1:
The planetary gear unit enables dynamic torque distribution among the sun gear, ring gear, and carrier. By allowing differential rotation, the system adapts the inertia torque generation to operating conditions, preventing excessive inertia torque at high speeds while maintaining effective damping at low speeds
Solution Approach 2:
The system changes the operational parameters of the ring gear from fixed inertia mass to a dynamically adjustable element. Through the planetary gear mechanism, the effective inertia torque is modulated based on the relative rotation between input and output elements, optimizing damping performance across different speed ranges
2Reliability
If the pinion gears are oscillated within a larger range to improve vibration suppression, then damping effectiveness increases, but torque transmission efficiency decreases and may cause excessive backlash
Solution Approach 1:
Different oscillation ranges are designated for different operating conditions: a first oscillating range for low torque conditions and a second oscillating range for high torque conditions. This local optimization ensures effective vibration suppression when needed while maintaining torque transmission efficiency during normal operation
Solution Approach 2:
The oscillation range of the pinion gears is made dynamic rather than fixed. The system automatically adjusts the oscillation amplitude based on the applied torque, expanding the oscillation range only when vibration suppression is required and maintaining normal meshing when torque transmission is the priority
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 solution maintains vibration damping performance across high speed ranges by reducing torque transmission efficiency during high-speed operation, allowing inertia torque to overwhelm vibratory forces and prevent vibration transmission, thus ensuring effective damping.
Implementation Method 1
an elastic member is interposed between the input element and the output element to be deformed elastically by a torsional torque causing a relative rotation between the input element and the output element
Implementation Method 2
still another one of the sun gear, the ring gear, and the carrier serves as an inertia element that is rotated relatively to the input element and the output element by an inertia force
Implementation Method 3
each of the pinion gears is individually moved from an initial position when the relative rotation between the input element and the output element is caused by the torsional torque, and individually oscillated by a pulsation of the torque delivered to the input element from the engine
Data Source
AI summary
A torsional vibration damper whose vibration damping performance will not be reduced in a high speed range. In the torsional vibration damper, a planetary gear is oscillated within a first oscillating range when a torsional torque is smaller than a reference torque, and within a second oscillating range when the torsional torque is greater than the reference torque. Each backlash between the pinion gear and at least one of a sun gear and a ring gear within the second oscillating range is individually wider than each backlash between the pinion gear and the sun gear and each backlash between the pinion gear and the ring gear within the first oscillating range.