Vehicle-Sensitive Sensor with Composite Mass for Noise Reduction
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Solution Overview
Problem
Existing vehicle-sensitive sensors for self-locking belt retractors produce unwanted noise and fail to securely tilt during vehicle acceleration and drop tests, with potential contamination affecting their functionality.
Innovation Solution
A vehicle-sensitive sensor design utilizing a sensor mass composed of different materials, where a softer, lower-density material contacts the carrier part to absorb vibrations and reduce noise, and a denser material ensures reliable tilting, with a locking lever configuration that prevents detachment and contamination protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the sensor mass is made entirely of soft rubber-type or plastic-type materials to reduce noise generation, then noise emissions are reduced, but the sensor mass requires a relatively complicated and large geometry in order to tilt onto the supporting face during vehicle acceleration
Solution Approach 1:
The sensor mass is constructed as a composite object comprising a soft sensor part (made of rubber-type or plastic-type material) and a dense mass part (made of metal or hard plastic). The soft sensor part contacts the supporting face to reduce noise through vibration absorption, while the dense mass part provides sufficient weight for reliable tilting during acceleration without requiring increased volume or geometric complexity.
Solution Approach 2:
Different regions of the sensor mass are assigned different material properties: the sensor part that contacts the supporting face is made of soft material for noise reduction, while the mass part that provides gravitational force for tilting is made of dense material. This local differentiation of material quality allows each region to fulfill its specific function optimally.
2Object-generated harmful factors
If the sensor mass is made entirely of soft rubber-type or plastic-type materials to reduce noise generation, then noise emissions are reduced, but the sensor mass volume must be increased to ensure reliable tilting during vehicle acceleration
Solution Approach 1:
The composite structure combines soft sensor part material with dense mass part material. The high density of the mass part compensates for its small volume, providing sufficient gravitational force for reliable tilting during acceleration, while the soft sensor part maintains low volume and effectively reduces noise through contact with the supporting face.
3Ease of operation
If the supporting face is exposed, then the sensor mass can tilt freely onto the supporting face, but contamination of the supporting face may occur, which prevents the sensor mass from tilting in one direction
Solution Approach 1:
The sensor mass acts as a protective cover that overlaps the supporting face in the installed state. This overlapping configuration protects the supporting face from contamination while still allowing the sensor mass to tilt freely onto the supporting face during vehicle acceleration, as the tilting motion occurs within the protected area.
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 sensor effectively reduces noise emissions and maintains operational reliability after drop tests and extended use, ensuring dependable tilting and secure engagement with the control disk.
Implementation Method 1
Since softer material absorbs vibrations when in contact with other objects, the sound emissions can be reduced
Implementation Method 2
The mass part disposed above the supporting face and having a greater density ensures that the sensor mass tilts dependably onto the supporting face during vehicle accelerations
Data Source
AI summary
A vehicle-sensitive sensor for a self-locking belt retractor, including a carrier part (4), a locking lever (2) including an engagement point (3), and a sensor mass (1) coupled to the locking lever (2), disposed as standing upright on a supporting face (5) of the carrier part (4) and tiltable with respect to the carrier part (4) The sensor mass (1) includes a sensor part (6), made of a first material, resting on the supporting face (5), and of a mass part (7), made of a second material, connected to the sensor part (6), disposed above the supporting face (5), wherein the first material forming the sensor part (6) has a lower density and a lesser hardness than the second material forming the mass part (7).