Tire Pressure Sensing Using Ambient Temperature Compensation
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Solution Overview
Problem
Conventional tire pressure monitoring systems (TPMS) struggle to provide accurate, real-time tire inflation pressures, especially for commercial vehicles, as they require tires to be at ambient temperature, which is impractical for vehicles in constant motion, and do not account for temperature fluctuations or atmospheric changes, leading to potential underinflation and uneven tire wear.
Innovation Solution
A system using external valve-stem sensors and an electronic control unit to calculate 'effective' tire inflation pressure based on a moving average of ambient temperature, accounting for changes in atmospheric pressure, and allowing real-time monitoring and adjustment without the need for a pressure gauge, enabling drivers to maintain proper tire pressure regardless of tire temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional TPMS uses fixed cold temperature (65°F) for pressure calculation, then the system is simple to implement, but the tire pressure accuracy deteriorates in varying temperature conditions
Solution Approach 1:
The system transitions from a static fixed temperature assumption (65°F) to a dynamic ambient temperature measurement using a temperature sensor that continuously tracks actual environmental conditions. This allows the pressure calculation to adapt to varying temperature conditions, resolving the contradiction between system simplicity and measurement accuracy.
Solution Approach 2:
The system changes the temperature parameter from a fixed constant (65°F) to a variable measured by a temperature sensor. This parameter change enables accurate pressure calculations across different environmental conditions while maintaining system simplicity through direct sensor measurement rather than complex calculations.
2Measurement precision
If TPMS requires tires to be at ambient temperature for accurate pressure reading, then the pressure measurement is accurate, but the system cannot provide real-time monitoring for vehicles in constant motion
Solution Approach 1:
The system performs preliminary temperature compensation by measuring ambient temperature and using it to calculate what the tire pressure would be at ambient temperature conditions. This allows the system to provide accurate real-time pressure readings even when tires are hot, eliminating the need to wait for tires to cool down.
Solution Approach 2:
The system introduces ambient temperature measurement as an intermediary parameter that mediates between the hot tire pressure reading and the desired cold pressure equivalent. By measuring ambient temperature and using it in the pressure calculation, the system bridges the gap between actual hot tire conditions and the reference cold temperature condition.
3Ease of operation
If TPMS does not account for temperature fluctuations, then the system is simple to operate, but tire underinflation and uneven wear occur
Solution Approach 1:
The system implements feedback by continuously measuring ambient temperature and using this information to adjust the pressure calculation. This feedback loop ensures that temperature fluctuations are automatically compensated for, maintaining reliable tire inflation without requiring complex user intervention or system operation changes.
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
Enables real-time monitoring and adjustment of tire pressures, reducing the risk of underinflation and uneven wear, extending battery life by reporting only significant pressure changes, and providing alerts for low-pressure conditions, even when the vehicle is in operation.
Implementation Method 1
The transmitter detects an internal pressure of the tire at a predetermined time interval, and wirelessly transmits an internal pressure value of the tire
Implementation Method 2
The contained air temperature of a tire has a significant impact on its inflation pressure
Implementation Method 3
A 'hot' tire typically is 50-60° F. above ambient temperature, leading to pressure increases of 10-15 psi above the cold inflation pressure
Data Source
AI summary
A real time tire pressure sensing system includes sensors to collectively generate signals corresponding to a contained tire air temperature, a contained inflation pressure, and an ambient temperature associated with a tire mounted on a vehicle. A processor determines an effective tire inflation pressure based on the generated signals and further at least on a calculated moving average of the ambient temperature (e.g., over a defined time period such as 24 hours) and generates real time notifications associated with the determined effective tire inflation pressure to specified user interfaces. At least one sensor may be an inflation pressure sensor configured to generate event-based signals corresponding to detected changes per unit pressure. The processor may further generate real time feedback control signals to an automatic tire inflation device, based on the determined effective tire inflation pressure, or enable and prompt manual control of the tire inflation device via the user interface.