Tyre Pressure Transmitter Using Pulse Position Modulation
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Solution Overview
Problem
Existing tire pressure monitoring systems fail to transmit data reliably at high speeds and are insufficiently reliable in extreme temperatures (-40°C to +125°C due to high battery current consumption, especially when using UHF- and VHF-frequency transmission.
Innovation Solution
An apparatus with a radio-frequency transmitter and receiver system using a Surface Acoustic Wave resonator, Pulse Position Modulation, and a low-power circuit configuration, where the valve body acts as an antenna, allowing for low-power transmission compliant with automotive regulations, and utilizing a microcontroller and a small battery with low current absorption, enabling efficient data transmission in short bursts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If UHF- and VHF-frequency transmission is employed for data transmission, then data transmission capability is improved, but battery current consumption increases significantly
Solution Approach 1:
The transmitter operates in periodic bursts rather than continuously, transmitting data only when triggered by the inflating device. This intermittent operation dramatically reduces average current consumption while maintaining data transmission capability when needed.
Solution Approach 2:
The system dynamically adjusts its operation mode based on whether the wheel is stationary or rotating. When the wheel rotates, the transmitter remains inactive and data is stored in memory. Transmission occurs only when the wheel is stationary and the inflating device triggers it, optimizing energy usage based on operational conditions.
2Device complexity
If traditional transmission systems with 3 volt power supply are used, then device simplicity is maintained, but current consumption reaches 20 milliamperes which exceeds battery capability
Solution Approach 1:
The transmitter uses periodic burst transmission instead of continuous operation. By transmitting data in short bursts only when triggered, the average current consumption is reduced from 20mA to levels suitable for small lithium batteries, while maintaining the same transmission system architecture.
Solution Approach 2:
The system changes its operational parameters based on wheel rotation state. When the wheel rotates, transmission is suppressed and data is stored. When stationary and triggered by the inflating device, transmission occurs. This parameter change optimizes energy consumption without requiring a complete system redesign.
3Loss of information
If continuous transmission operation is used, then data availability is improved, but battery lifetime decreases due to high current demand
Solution Approach 1:
The transmitter operates periodically rather than continuously, transmitting data only when triggered by the inflating device during stationary periods. This extends battery lifetime by reducing average current draw while ensuring data is transmitted when the vehicle is not in motion.
Solution Approach 2:
The system dynamically switches between storage mode (when wheel rotates) and transmission mode (when wheel is stationary and triggered). This dynamic operation ensures data availability when needed while extending battery lifetime by avoiding transmission during high-current-demand conditions.
4Weight of moving object
If small dimension battery is used to reduce weight, then weight reduction is achieved, but current output capability becomes insufficient especially at low temperatures
Solution Approach 1:
The transmitter uses periodic burst transmission with long intervals between transmissions. This allows the use of small, lightweight batteries with limited current output capability, as the average power demand is reduced to levels these batteries can sustain even at low temperatures.
Solution Approach 2:
The system dynamically controls transmission based on wheel rotation detection. Transmission occurs only when the wheel is stationary and the inflating device triggers it, preventing high current demands that would exceed the capabilities of small lightweight batteries, especially in cold conditions.
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 reliable data transmission at high speeds and low temperatures with significantly reduced battery consumption, ensuring compliance with automotive regulations and minimizing interference from radio wave reflections.
Implementation Method 1
a transmitter (1) located inside a tyre (T) and comprising a battery (11), a microcontroller (12), a transmission section (13) with an oscillator (15) and an antenna (14)
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
An apparatus is described for monitoring the pressure in at least one tyre; the tyre is coupled to the rim of a wheel of a vehicle and includes an inflating device (10) and a sensor (34) for measuring the gas pressure inside the tyre. The apparatus includes a transmitter (1) and a receiver (2) and the inflating device includes said transmitter (1). The transmitter (1) is connected to the sensor (34) and is capable of transmitting a signal (TX) representing the pressure in the tyre; the receiver (2) is suitable for the signal coming from the transmitter. The transmitter (1) includes means (12, 13, 15) for processing the signal and an antenna (14) for transmitting the signal. The processing means (12, 13, 15) are capable of effecting a pulse position modulation of the signal (TX) representing the pressure in the tyre. (Fig. 1).