Zero-Strain Soil Pressure Sensor with Hydraulic Balancing
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Solution Overview
Problem
Current zero-strain soil pressure sensors suffer from significant measurement errors due to the soil arch effect and soil displacement caused by deformation of elastic films, which cannot be completely eliminated by existing single- or double-film designs.
Innovation Solution
A zero-strain soil pressure sensor design featuring a hydraulic oil cavity, outer and inner elastic films, strain bridge circuits, and a driving mechanism with a stepping motor and piston to control oil pressure, ensuring the outer elastic film remains non-deforming and only the inner film deforms, thus avoiding measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single elastic film is used to convert soil pressure into deformation, then the sensor structure is simple, but soil arch effect and soil displacement occur causing measurement errors
Solution Approach 1:
The sensor is divided into multiple functional components: outer elastic film, inner elastic film, hydraulic oil cavity, and piston. The outer film contacts soil while the inner film measures pressure, with the hydraulic system separating their functions to eliminate measurement errors caused by soil arch effect.
Solution Approach 2:
Hydraulic oil serves as an intermediary medium between the outer elastic film and the inner elastic film. The oil transmits pressure from the outer film to the inner film without direct mechanical contact, preventing soil displacement and arch effect from affecting the measurement.
2Measurement precision
If a double-film structure is adopted to eliminate soil arch effect, then measurement accuracy improves, but deformation of the first film still occurs when the second film deforms causing residual errors
Solution Approach 1:
Hydraulic oil acts as an intermediary that decouples the deformation of the outer elastic film from the inner elastic film. When the outer film deforms under soil pressure, it transmits pressure through the incompressible hydraulic oil to the inner film, preventing direct mechanical coupling that causes residual errors.
Solution Approach 2:
The patent uses a hydraulic oil cavity filled with incompressible hydraulic oil to transmit pressure between the outer and inner elastic films. The hydraulic system allows pressure transmission without mechanical deformation coupling, eliminating the residual errors present in mechanical double-film structures.
3Ease of operation
If the outer elastic film deforms to measure soil pressure, then the measurement principle is straightforward, but soil displacement and arch effect are generated affecting accuracy
Solution Approach 1:
The measurement function is segmented between two films: the outer elastic film interacts with soil to sense pressure, while the inner elastic film performs the actual measurement. This segmentation allows the outer film to deform without directly affecting measurement accuracy.
Solution Approach 2:
Hydraulic oil serves as an intermediary that transfers pressure from the outer film to the inner film without requiring the inner film to directly contact soil. This eliminates soil displacement and arch effect from the measurement process while maintaining measurement simplicity.
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 design achieves more accurate soil pressure measurement by balancing external soil pressure with controlled oil pressure, preventing soil arch effect and displacement, and ensuring the measured pressure is accurately represented by the inner elastic film.
Implementation Method 1
The hydraulic oil cavity (5) is filled with hydraulic oil. The piston (7) is connected with the driving mechanism and arranged in the hydraulic oil cavity (5)... the oil pressure in the hydraulic oil cavity (5) and the external soil pressure are kept balanced
Implementation Method 2
an outer strain bridge circuit (31) arranged at the lower end of the outer elastic film (3)... an inner strain bridge circuit (41) arranged at the lower end of the inner elastic film (4)
Data Source
AI summary
A zero-strain soil pressure sensor includes a shell provided with a hydraulic oil cavity and a cavity located below the hydraulic oil cavity, a processor, an outer elastic film arranged at the upper end of the hydraulic oil cavity, an inner elastic film arranged between the hydraulic oil cavity and the cavity, an outer strain bridge circuit connected with the outer elastic film, an inner strain bridge circuit connected with the inner elastic film, a piston communicated with the hydraulic oil cavity, and a driving mechanism connected with the piston. The outer strain bridge circuit, the inner strain bridge circuit and the driving mechanism are electrically connected with the processor. The invention has the beneficial effect that the piston is driven by the driving mechanism to control the oil pressure in the hydraulic oil cavity, external soil pressure is balanced through the oil pressure to keep the outer elastic film in an non-deforming state all the time, and only the inner elastic film is deformed, so that the soil arch effect and soil displacement are avoided, and thus the liquid pressure measured by the inner elastic film is the soil pressure, and the measurement result is more accurate.