Piston Temperature Measurement Using Passive SAW Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for measuring piston temperatures in internal combustion engines are labor-intensive, mechanically stressful, and costly, with limitations in precision and complexity, particularly due to the need for energy supply and radio transmission in existing technologies.
Innovation Solution
The use of passive Surface Acoustic Wave (SAW) sensors that measure temperature by detecting shifts in resonant frequency without requiring external power or complex antenna systems, allowing flexible placement on the piston and enabling long-term temperature monitoring across various load points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If radio telemetry with power supply is used for temperature measurement, then temperature data can be transmitted wirelessly, but the device complexity and cost increase due to power supply requirements
Solution Approach 1:
The patent extracts and removes the power supply component from the measurement system by using passive SAW sensors that derive energy from the excitation signal itself, eliminating the need for batteries or power management circuits while maintaining wireless transmission capability
Solution Approach 2:
The patent replaces the electromagnetic power supply system with a mechanical wave-based energy transfer mechanism, where the excitation signal mechanically vibrates the SAW structure to generate the measurement signal, substituting electrical power requirements with acoustic energy utilization
2Ease of manufacture
If thermal markers are used for temperature measurement, then temperature threshold detection is simple, but temporal resolution information is lost
Solution Approach 1:
The patent employs periodic excitation signals that continuously probe the SAW sensor, generating time-resolved frequency measurements that capture temporal temperature variations while maintaining the simplicity of threshold-based detection through frequency analysis
Solution Approach 2:
The patent transforms the static temperature threshold detection of thermal markers into a dynamic measurement by utilizing frequency parameter changes in the SAW resonance, where temperature variations directly modulate the resonant frequency to provide continuous temporal information
3Measurement precision
If multiple sensors are placed on the piston for comprehensive temperature monitoring, then measurement coverage improves, but the mechanical strength and structural integrity are compromised
Solution Approach 1:
The patent segments the measurement function into multiple independent passive SAW sensors that can be distributed across the piston surface, each providing localized temperature data without requiring complex integration that would compromise structural integrity
Solution Approach 2:
The patent utilizes thin-film SAW sensor structures that can be conformally applied to the piston surface, providing comprehensive temperature coverage through flexible placement while maintaining minimal impact on the underlying piston strength and structural properties
4Device complexity
If direct cable transmission is used for sensor data, then the system is simple, but measurement accuracy deteriorates due to mechanical stress on cables
Solution Approach 1:
The patent replaces the mechanical cable transmission system with wireless electromagnetic signal transmission, eliminating the physical cable that suffers from mechanical stress and signal degradation, thereby maintaining transmission simplicity while improving measurement accuracy through contactless signal delivery
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 approach reduces technical effort and cost while providing accurate, precise temperature measurements over extended periods, suitable for diverse internal combustion engine types, including hybrid technologies, without the need for energy supply or complex transmission systems.
Implementation Method 1
SAW sensors utilize the dependence of the surface wave speed on mechanical stress (deformation), mass loading (deposits on the surface), or temperature (temperature coefficient of the speed of sound)
Implementation Method 2
By exciting the sensors in the region of the resonant frequency, the ambient-condition-dependent resonant frequency is returned
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Described is an internal combustion engine having at least one cylinder (1) and having at least one piston (2), wherein the piston has at least one passive sensor (3) and at least one antenna (4) which communicates with the sensor (3), and at least one antenna (5) which communicates with the antenna fastened to the piston.