Vehicle Transaxle Resonator Layout for Abnormal Noise Reduction
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Solution Overview
Problem
Vehicle transaxles experience abnormal noise due to vibrations from DC/DC converters and inverters, which resonate with the housing cases, leading to unwanted sound emissions.
Innovation Solution
Incorporating a resonator with a cavity and opening between the transaxle case and the housing cases, where the volume of the cavity and opening are set to have a resonance frequency lower than the natural frequency of the housing case walls, preventing resonance and noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the housing case walls are made rigid to accommodate vibration elements, then structural strength is improved, but resonance noise increases when excited by vibrations
Solution Approach 1:
A resonator is introduced as an intermediary component between the vibration source (DC/DC converter or inverter) and the housing case walls. The resonator absorbs and dissipates vibration energy, preventing it from being transmitted to the housing case walls and causing resonance noise, while allowing the walls to maintain their rigid structure for structural strength.
Solution Approach 2:
The resonator's physical parameters (cavity volume, opening area, shape) are specifically designed and adjusted to tune its resonance frequency to match or be close to the natural frequency of the housing case walls. This parameter optimization enables the resonator to effectively absorb vibration energy at the problematic frequency range, reducing resonance noise while preserving structural integrity.
2Ease of manufacture
If the housing case is fixed at a predetermined interval to the transaxle case, then assembly simplicity is improved, but abnormal noise occurs due to resonance between the housing case and transaxle case
Solution Approach 1:
The resonator serves as a mediator placed within the housing case to decouple the vibration transmission path between the vibration source and the transaxle case. It absorbs vibration energy before it can be transmitted through the housing case to the transaxle case, preventing abnormal noise while maintaining the simple fixed-connection assembly structure.
3Object-generated harmful factors
If the cavity volume and opening volume are increased to lower the resonator's resonance frequency, then noise reduction effectiveness is improved, but the space required in the housing case increases
Solution Approach 1:
The resonator's cavity volume and opening area are precisely optimized to achieve the desired resonance frequency (matching or close to the natural frequency of the housing case walls) while minimizing the space occupied. This parameter optimization balances noise reduction effectiveness with compact design, allowing the resonator to fit within the available space in the housing case.
Solution Approach 2:
The resonator is designed with a compact three-dimensional structure that efficiently utilizes the available space within the housing case. By optimizing the spatial arrangement and dimensional proportions of the cavity and opening, the resonator achieves effective noise reduction without occupying excessive volume, allowing for compact integration into the transaxle assembly.
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
Effectively reduces abnormal noise by ensuring the resonator does not resonate with the housing case walls, even when they vibrate at their natural frequencies, thereby minimizing sound emissions from the transaxle.
Implementation Method 1
a resonator 44 functioning as an abnormal noise reduction device is provided between the first housing case 36 and the second housing case 38. The resonator 44 has a cavity 46 and an opening 48. The volume V of the cavity 46 and a volume Vk of the opening 48 are set such that a resonance frequency fh of the resonator 44 is lower than natural frequencies f1 and f2 of the first facing wall 36a and the second facing wall 38a
Data Source
AI summary
A resonator having a cavity and an opening is formed. The cavity is formed between a transaxle case and a facing wall, of a first housing case, that faces the transaxle case. The opening is configured such that the cavity is partially opened to a lateral side through the opening. A volume of the cavity and a volume of the opening are set such that a resonance frequency of the resonator is lower than a natural frequency of the facing wall of the first housing case. Since the resonance frequency of the resonator is lower than the natural frequency of the facing wall, even when the facing wall vibrates at the natural frequency, the cavity does not resonate. Hereby, abnormal noise caused from the transaxle can be reduced.