Acoustic Waveguide Temperature Compensation via Fuel Flow
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Solution Overview
Problem
Existing fuel level measurement devices face inaccuracies due to temperature variations, especially when the liquid level is low, as the temperature in the reference system may differ from other parts of the device, leading to erroneous measurements.
Innovation Solution
The solution involves directing the fuel flow along the exterior of the waveguide above the fuel level, using the suction and/or return pipe of a fuel pump to ensure consistent temperature throughout the waveguide, eliminating the need for additional components and reducing costs, and integrating the waveguide with the suction and/or return pipe for manufacturing ease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference system is used to determine the current speed of sound, then measurement accuracy is improved, but temperature differences between the reference system and other parts of the device still cause measurement errors
Solution Approach 1:
The waveguide is thermally coupled with the suction/return pipe of the fuel pump, merging the measurement function with the fuel circulation system. This ensures that the waveguide experiences the same temperature conditions as the fuel in the tank, eliminating temperature differential errors between reference and measurement zones.
Solution Approach 2:
The suction/return pipe acts as an intermediary thermal conductor, transferring the temperature of the circulating fuel to the waveguide. This intermediary ensures thermal equilibrium between the measurement medium and the acoustic path without requiring direct thermal contact between the waveguide and tank walls.
2Measurement precision
If additional dedicated means are added to direct fuel flow along the waveguide, then temperature compensation is improved, but device complexity and cost increase
Solution Approach 1:
The suction/return pipe of the fuel pump serves dual functions: it circulates fuel through the engine system and simultaneously acts as a thermal coupling conduit for the waveguide. This multi-functionality eliminates the need for dedicated temperature compensation components while achieving accurate measurements.
Solution Approach 2:
The existing fuel pump system provides its own thermal field for measurement purposes. The circulating fuel naturally cools or heats the waveguide to match tank conditions, making the system self-compensating without external intervention or additional active components.
3Ease of manufacture
If the waveguide is integrated with the suction and/or return pipe, then manufacturing and assembly are simplified, but the structural design becomes more complex
Solution Approach 1:
The waveguide and suction/return pipe are merged into a single integrated component or closely coupled assembly. This integration eliminates separate mounting operations and reduces the number of parts, simplifying manufacturing and assembly despite requiring a customized structural design.
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 provides accurate temperature-compensated fuel level measurements by maintaining consistent sound velocity throughout the waveguide, particularly beneficial for diesel fuel where temperature is the primary concern, and reduces the complexity and cost of the measurement device.
Implementation Method 1
an acoustic signal is transmitted from the transducer into the waveguide, which signal is reflected by the surface of the liquid into which the waveguide extends
Implementation Method 2
part of the waveguige is arranged alongside the suction and/or return pipe so that the temperature of the latter can be transferred to the former
Data Source
Figure 1a~1b
Figure 2a
Figure 2b~2c
AI summary
The present invention relates to a device (10) for providing a temperature compensated measurement of the level of a liquid (14) in a tank (12; 30). The device comprises a transducer (22) for transmitting and receiving acoustic signals, and a waveguide (24) connected to the transducer and adapted to extend into the liquid. The device is characterized by means (16; 18; 40) for directing a flow of liquid originating from the tank of along the exterior of a portion of the waveguide which during operation is located above the liquid level. The present invention also relates to a corresponding method for providing a temperature compensated measurement of the level of a liquid in a tank.