Brake Pad Piezoceramic Signal Conditioning for High-Temperature Sensing
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Solution Overview
Problem
Existing braking devices with piezoceramic sensors face challenges in conditioning electrical signals due to high operating temperatures, complex and costly shielding requirements, and the need for accurate signal conditioning over long periods, especially in high-temperature environments with limited installation space.
Innovation Solution
A compact, economical, and temperature-resistant passive conditioning circuit with a resistor in parallel to the piezoceramic sensor and AC coupling capacitance, integrated directly into the brake pad or cable, which transforms charge signals into voltage signals and includes a digital stage for processing, eliminating the need for traditional charge amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional charge amplifiers are used for signal conditioning, then signal conditioning capability is provided, but the device cannot survive high operating temperatures greater than 350°C
Solution Approach 1:
The patent replaces the traditional electronic charge amplifier with a purely mechanical passive conditioning circuit consisting of resistors and capacitors. This mechanical/electrical passive system can withstand high temperatures greater than 350°C without the electronic components that limit traditional amplifiers, while still providing the necessary signal conditioning function through passive RC networks.
Solution Approach 2:
The patent changes the operating parameter range by designing a passive circuit that operates reliably at temperatures greater than 350°C, whereas traditional charge amplifiers fail at these temperatures. The passive components are selected with parameters suitable for high-temperature operation, eliminating the need for active electronic components.
2Measurement precision
If effective shielding is applied against external disturbances, then signal integrity is improved, but the implementation becomes complex and costly
Solution Approach 1:
The patent replaces the need for complex electromagnetic shielding with a passive electrical conditioning circuit that inherently rejects external disturbances. The passive RC circuit conditions the signal at the source without requiring additional shielding structures, reducing both complexity and cost while maintaining signal integrity.
Solution Approach 2:
The passive conditioning circuit provides self-protection against external disturbances through its inherent passive design. The circuit naturally filters and conditions the signal without requiring external shielding structures, making the system self-sufficient in protecting against environmental interference.
3Object-affected harmful factors
If proper screening is implemented for high impedance sensors, then external disturbance rejection is improved, but installation space requirements increase
Solution Approach 1:
The patent merges the signal conditioning function and the disturbance rejection function into a single integrated passive circuit located at the sensor. By combining these functions in one compact passive network, the system achieves both disturbance rejection and space efficiency without requiring separate shielding structures and conditioning circuits.
Solution Approach 2:
The patent replaces bulky physical shielding structures with a compact passive electrical circuit that provides equivalent or superior disturbance rejection. The passive RC network occupies minimal space compared to traditional electromagnetic shielding while effectively rejecting external disturbances on the high-impedance sensor signal.
4Speed
If charge amplifiers with large bandwidth are used, then signal frequency range is improved, but circuit stability and sensitivity drift over time
Solution Approach 1:
The patent replaces the active charge amplifier with a passive conditioning circuit that provides frequency-dependent signal conditioning without the instability and drift problems of active electronics. The passive RC network maintains stable characteristics over time while providing the necessary bandwidth for the sensor signal through its frequency response characteristics.
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 solution provides high stability, sensitivity, and accuracy in signal conditioning without drifting over time, while being simple, compact, and resistant to high temperatures, effectively addressing the limitations of prior art by minimizing external disturbances and maintaining high signal integrity.
Implementation Method 1
the piezoceramic sensors, when subjected to mechanical stress due to the interaction between the block of friction material and the disc bound to the wheel, generate an electrical signal
Implementation Method 2
A compact, economical, and temperature-resistant passive conditioning circuit with a resistor in parallel to the piezoceramic sensor and AC coupling capacitance, integrated directly into the brake pad or cable, which transforms charge signals into voltage signals
Data Source
Figure 1~3
Figure 4
Figure 5A
AI summary
A braking device for vehicles, comprising a support element, a block of friction material supported by the support element, and electrically isolated electrical circuit that has at least one piezoceramic sensor and is interposed between the block of friction material and the support element, said braking device comprising a conditioner for conditioning the electrical signal of said at least one piezoceramic sensor comprising a passive analog stage for measurement and a processing digital stage for processing the output signal from said passive analog stage, the passive analog stage comprising a charge derivative electrical circuit, the processing digital stage being a stage for digitization and integration of the output signal from said passive analog stage, the passive analog stage for measurement being integrated in said support element or in an electric cable connector of said electrical circuit for transferring said electrical signal or in said cable, the processing digital stage being remotely located from the passive analog stage.