Piezoelectric Mass Particle Sensor with Tapered Feed and Damping
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Solution Overview
Problem
Existing devices for detecting mass particles in ducted air streams struggle to achieve precise counting of particles of different shapes while ensuring the sensor element is easily installable and resistant to contamination, with issues of overcounting and inadequate impact pressure.
Innovation Solution
A sensor element is positioned in a deflection section of a line with a tapering feed section that ensures all mass particles hit the impact surface once, combined with a damping disc for impact resistance and electrical connection, and a transfer section that widens to reduce flow velocity and prevent turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor element is integrated into a duct to count mass particles, then particle counting capability is achieved, but the sensor element becomes vulnerable to contamination and mechanical damage
Solution Approach 1:
The sensor element is segmented into distinct functional components: a protective housing that interfaces with the duct, an impact surface for particle reception, a piezoelectric element for signal generation, and a damping element for signal filtering. This segmentation allows each component to be optimized independently - the housing provides protection while the impact surface maintains exposure for accurate counting.
Solution Approach 2:
An impact surface is introduced as an intermediary between the mass particles and the piezoelectric sensor element. This intermediary transfers the mechanical impact from particles to the sensor while protecting the sensor from direct exposure to contamination. The impact surface can be cleaned or replaced without affecting the sensitive piezoelectric element.
2Measurement precision
If the sensor element is positioned to maximize particle impact, then counting accuracy improves, but the sensor becomes more exposed to harsh environmental conditions
Solution Approach 1:
The sensor assembly is divided into an exposed impact surface region and a protected internal region containing the piezoelectric element. The impact surface is designed to receive particle impacts at optimal angles for detection, while the piezoelectric element remains shielded within the housing, reducing its exposure to harmful environmental factors.
Solution Approach 2:
A damping element is positioned between the impact surface and the piezoelectric element to provide beforehand cushioning. This damping element absorbs excessive mechanical shocks and vibrations from particle impacts, protecting the piezoelectric element from damage while still allowing sufficient signal transmission for accurate counting.
3Measurement precision
If a tapered feed section is used to direct all particles onto the impact surface, then counting completeness improves, but flow velocity increases reducing particle impact force
Solution Approach 1:
The feed section is designed with a tapered geometry that changes the flow parameters gradually. The taper angle and length are optimized to redirect particles onto the impact surface while maintaining sufficient impact velocity. By controlling the taper parameters, the system achieves complete particle interception without excessive acceleration that would reduce impact force.
Solution Approach 2:
The feed section employs curved surfaces rather than sharp angles to redirect the particle-laden airflow. These curved surfaces gently guide particles onto the impact surface, maintaining their forward momentum and impact force while ensuring all particles are directed onto the sensing area.
4Ease of operation
If the sensor element is easily installable with simple mounting, then installation time reduces, but the mounting may not provide adequate vibration isolation and sealing
Solution Approach 1:
The sensor element is designed as a nested assembly where the piezoelectric element is housed within a protective housing that includes mounting features. This nested structure allows the entire sensor assembly to be installed as a single unit while maintaining internal vibration isolation and sealing arrangements. The housing contains integrated sealing elements and mounting interfaces that provide adequate protection without complicating installation.
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 configuration allows for precise counting of mass particles, including seeds, with high grain accuracy and minimal impact on flow mechanics, while preventing overcounting and ensuring the sensor element is robust and easy to install.
Implementation Method 1
The sensor element has a piezoelectric element that is connected to an impact surface
Implementation Method 2
A damping element and a rigid base body are connected to the piezoelectric element on the side facing away from the interior of the duct
Data Source
Figure 1~2
AI summary
The invention relates to a device for detecting mass particles in guided air streams, in particular seeds to be sown in seed drills, comprising a line (1) through which the air stream containing the mass particles is guided, a sensor element (3) arranged on the line (1), the sensor element (3) comprising a piezoelectric element (9), an impact surface arranged on a side of the piezoelectric element facing the interior of the line (1), and a rigid base body arranged on a side of the piezoelectric element facing away from the interior of the line, the sensor element (3) being arranged in a deflection section (2) of the line (1), and an upstream feed section (31) of the line (1) tapering in the flow direction (S) such that essentially all mass particles conveyed in the feed section (31) and to be detected strike the impact surface (8) of the sensor element (3) at least once.wherein a damping element (10) is arranged on a side of the piezoelectric element (9) facing away from the interior of the conductor (1).