Acceleration Sensor Motion Transformation for Vibration Robustness
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Solution Overview
Problem
Existing acceleration sensors face challenges in achieving robustness to vibrations while maintaining high dynamic damping and precise measurement, particularly in environments with strong high-frequency vibrations, as lowering the resonant frequency increases deflection amplitude and risks mechanical contact between electrodes.
Innovation Solution
The acceleration sensor employs a transformation means to convert the deflection motion into a detection motion with a lower amplitude, allowing for a lower resonant frequency without mechanical contact, utilizing a MEMS component with a semiconductor substrate and a detection unit structured as a plate capacitor for enhanced dynamic air damping and sensitivity, incorporating slide film or squeeze film damping to reduce resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonant frequency is lowered to improve robustness to vibration, then the robustness to vibration is improved, but the amplitude of deflection motion increases leading to mechanical contact between electrodes
Solution Approach 1:
The patent divides the motion system into two separate components: a seismic mass that performs large-amplitude deflection motion and a detection unit that performs small-amplitude detection motion. This segmentation allows the seismic mass to achieve large deflections for improved vibration robustness while the detection unit maintains small amplitudes to avoid electrode contact.
Solution Approach 2:
The patent introduces a transformation means as an intermediary mechanism between the seismic mass and detection unit. This transformation means converts the large deflection motion of the seismic mass into small detection motion of the detection unit, enabling both large deflection amplitude for vibration robustness and small detection amplitude to prevent electrode contact.
2Reliability
If large deflections are implemented to achieve lower resonant frequency, then the robustness to vibration is improved, but mechanical contact is created between fixed electrodes and counterelectrodes
Solution Approach 1:
The patent separates the functions of large deflection and precise measurement into distinct components. The seismic mass handles large deflections for vibration robustness while the detection unit with its separate electrode structure performs precise measurement without experiencing the full deflection amplitude, thus avoiding electrode contact.
Solution Approach 2:
The transformation means acts as an intermediary that decouples the large deflection motion from the detection electrodes. By transforming the motion amplitude, it protects the detection unit's electrodes from mechanical contact while still transmitting the acceleration information for measurement.
3Object-affected harmful factors
If small deflections are used to avoid electrode contact, then mechanical contact is prevented, but the measuring signal becomes too small at low acceleration forces
Solution Approach 1:
The patent segments the system so that the seismic mass generates large deflections for strong measurement signals while the detection unit experiences only transformed small deflections. This allows the measuring signal to remain strong (from seismic mass deflection) while preventing electrode contact (at detection unit).
Solution Approach 2:
The transformation means serves as an intermediary that preserves the measurement information from large deflections while reducing the amplitude to safe levels for the detection electrodes. This enables strong measuring signals without electrode contact.
4Measurement precision
If the detection unit is positioned close to fixed electrodes to improve capacitance sensitivity, then measurement precision is improved, but the risk of mechanical contact increases
Solution Approach 1:
The transformation means acts as an intermediary that allows the detection unit to be positioned optimally for capacitance sensitivity while ensuring that the actual motion amplitude remains small enough to prevent electrode contact. The transformation decouples position from motion amplitude.
Solution Approach 2:
The patent changes the motion amplitude parameter through the transformation means, allowing the detection unit to maintain a position optimized for capacitance sensitivity while its actual displacement remains small, thus achieving both high measurement precision and low electrode contact risk.
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 design achieves improved robustness to vibrations, enabling precise measurement of small deflections and high sensitivity without increasing resonance, allowing the sensor to be installed in vibration-prone areas like the engine compartment without additional vibration-reducing measures, while maintaining accurate measurement accuracy.
Implementation Method 1
In response to an acceleration of the acceleration sensor, inertial forces act upon the seismic mass which deflect the seismic mass relative to the substrate, along a deflection direction
Implementation Method 2
Between the pairs of counterelectrodes and fixed electrodes functioning as plate capacitors, there form, in each case, electrical measuring capacitances whose contribution is a function of the respective distance between the fixed electrodes and the counter electrodes
Implementation Method 3
This is achieved by transferring the deflection motion to a detection motion, which has a lower amplitude as opposed to the deflection motion
Implementation Method 4
The damping properties of the acceleration sensor according to the present invention are preferably increased by slide film damping and/or squeeze film damping
Implementation Method 5
The damping properties of the acceleration sensor according to the present invention are preferably increased by slide film damping and/or squeeze film damping
Data Source
AI summary
An acceleration sensor has a substrate, a seismic mass and a detection unit. The seismic mass is configured to be deflected based on an external acceleration acting on the acceleration sensor, the deflection being in the form of a deflection motion with respect to the substrate along a deflection direction. The detection unit is configured to be deflected for the detection of a deflection of the seismic mass, the detection being in the form of a detection motion with respect to the substrate along a detection direction. The detection unit is connected to the seismic mass in such a way that the amplitude of the deflection motion along the deflection direction is greater than the amplitude of the detection motion along the detection direction.