Powertrain Mount Bracket Resonance Control
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Solution Overview
Problem
Conventional powertrain mount structures face issues with amplified noise due to overlapping resonance frequencies, and attempts to improve torsional rigidity can lead to increased bending rigidity, causing noise amplification.
Innovation Solution
A powertrain mount structure with a powertrain-side mount bracket featuring a middle fixation portion and a rigidity-reduction portion, which reduces bending rigidity and sets torsional and bending resonance points in optimal frequency ranges, thereby improving torsional rigidity and suppressing noise amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the powertrain-side mount bracket is designed with single extension portion to reduce resonance frequencies, then number of resonance frequencies decreases, but rigidity of the mount bracket becomes low
Solution Approach 1:
The connection portion uses variable thickness design where the thicker end regions provide structural strength and rigidity support, while the thinner middle region maintains flexibility and controls resonance characteristics. This local quality variation resolves the contradiction between rigidity and resonance frequency control.
2Strength
If middle fixation portion is positioned between fixation portions to strengthen torsional rigidity, then torsional strength improves, but bending resonance point shifts to high frequency range overlapping gear-noise band
Solution Approach 1:
The connection portion's non-uniform thickness creates local stiffness variations that decouple torsional and bending rigidity. The thinner middle section specifically reduces bending rigidity to keep bending resonance frequency below the gear-noise band, while the overall structure maintains adequate torsional strength.
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 proposed structure effectively sets torsional resonance points in high frequency ranges and bending resonance points in low frequency ranges, enhancing noise damping and reducing vehicle width direction rigidity, thus minimizing noise amplification.
Implementation Method 1
a mount rubber (53) which is attached to the extension portion (50a)
Implementation Method 2
setting a resonance frequency f0 of a bending mode at about 500 Hz in a low frequency range which does not influence both an engine-sound band and the gear-noise vibratory force band
Data Source
AI summary
A transmission-side mount bracket includes connection portions which connect a front-side leg portion and a rear-side leg portion of a leg member, a middle attachment (fixation) portion which is provided at the connection portions at a position located between the front-side leg portion and the rear-side leg portion and fixed to the powertrain, and a rigidity-reduction portion (an opening portion) which has the rigidity against a load applied in the vehicle width direction which is lower than that of the front-side leg portion and the rear-side leg portion and is provided at a position located in the vicinity of the middle attachment (fixation) portion.