Pulp Sound Insulating Member with Tuned Communication Passage
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Solution Overview
Problem
Conventional pulp molding methods for sound absorbing and insulating members limit the formation of a communication part's length dimension due to the thickness constraints of the molded article, restricting the absorption of specific sound frequencies.
Innovation Solution
A molding die with a recessed portion and projection portion allows for the independent formation of a communication part, enabling adjustment of the communication part's length and opening ratio to optimize sound absorption, and the integration of cellulosic fibers in a laminated state with additives for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional pulp molding is used to manufacture sound absorbing and insulating members, then the manufacturing process is simple, but the communication part's length dimension is limited by the molded article thickness, restricting sound absorption performance
Solution Approach 1:
The invention divides the molded article into multiple layers, with the communication part formed by aligning and bonding porous layers. This segmentation allows the communication part length to exceed the thickness of any single layer, resolving the limitation while maintaining pulp molding simplicity
Solution Approach 2:
The invention transitions from forming the communication part in a single-dimensional thickness direction to a multi-layer stacked structure, enabling length extension in the stacking direction while preserving the ease of pulp molding process
2Reliability
If the molded article thickness is increased to extend the communication part length, then sound absorption performance improves, but the manufacturing complexity and material usage increase
Solution Approach 1:
By segmenting the structure into multiple identical or similar porous layers that are stacked and bonded, the invention achieves extended communication part length without proportionally increasing overall structural complexity, as each layer can be manufactured using the same standardized process
Solution Approach 2:
The invention changes the structural parameter from a single thick layer to multiple thinner stacked layers, maintaining the total thickness needed for sound absorption while simplifying the manufacturing of each individual layer and enabling better quality control
3Productivity
If cellulosic fibers are laminated and dried in conventional pulp molding, then the molded article is formed, but the communication part remains unformed and requires separate processing
Solution Approach 1:
The invention performs preliminary action by pre-forming the communication part structure within the porous layers before final bonding. The communication part geometry is established during the layer formation stage, so no separate post-processing is needed after molding
Solution Approach 2:
The invention merges the communication part formation process with the main molding process by integrating it into the layer stacking and bonding operation, eliminating the need for separate communication part creation steps and improving overall manufacturing efficiency
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
This method enhances the sound absorption and insulation performance by allowing precise tuning of the communication part's dimensions and material properties, simplifying the manufacturing process and improving the sound absorbing and insulating member's effectiveness across a wider frequency range.
Implementation Method 1
The sound absorbing and insulating member can absorb the sound inside and/or outside the vehicle interior by using the resonance principle of Helmholtz
Implementation Method 2
a laminated body of cellulosic fibers has excellent sound absorbing performance and sound insulating performance
Data Source
AI summary
In a first step, a molding die is immersed in a raw liquid including cellulosic fibers. Then, the liquid of a raw liquid is sucked through a net material by a liquid suction part, so as to cause the cellulosic fibers to be laminated on the net material. In the second step, the cellulosic fibers laminated on the net material are dried, so as to form a protrusion. In the third step, the dried protrusion and the communication part are removed from the molding die. A passage part of the communication part is formed at a position where a projection portion had been arranged, the passage part being configured to communicate an inside of the protrusion with an outside of the protrusion.