Ultrasonic Sensor Diaphragm Insulation for Signal Interference
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Solution Overview
Problem
Ultrasonic sensors in motor vehicles face challenges in manufacturing costs and quality, particularly due to interference signals from the direct electrical connection between the piezo-electric element and the diaphragm, which affects the reception of reflected signals.
Innovation Solution
The ultrasonic sensor design includes a non-conducting paint layer on the piezo-electric element for insulation, with a radially outward flange on the diaphragm body and a decoupling element between the flange and the housing to prevent direct metallic contact, allowing for earth attachment without interference, and using an adhesive for secure fastening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a direct electrical connection is made between the piezo-electric element and the diaphragm, then the manufacturing is simpler, but interference signals occur that affect signal reception
Solution Approach 1:
A non-conducting layer is introduced as an intermediary between the piezo-electric element and the diaphragm. This layer electrically insulates the two components, preventing direct electrical contact that causes interference signals, while still allowing mechanical coupling for ultrasonic vibration transmission.
Solution Approach 2:
The electrical connection is segmented into separate conducting paths. The piezo-electric element is electrically isolated from the diaphragm, with separate earth attachments provided for both components, eliminating the interference caused by direct electrical connection while maintaining manufacturing feasibility.
2Device complexity
If the piezo-electric element is fastened directly to the diaphragm, then the assembly is simpler, but electrical interference occurs
Solution Approach 1:
The non-conducting layer serves as a mediator that enables mechanical fastening while preventing electrical interference. It allows the piezo-electric element to be securely attached to the diaphragm without creating a direct electrical path that would generate harmful interference signals.
Solution Approach 2:
The non-conducting layer is applied locally at the interface between the piezo-electric element and the diaphragm, providing electrical insulation exactly where needed. This localized approach eliminates interference signals without requiring complete redesign of the entire assembly structure.
3Device complexity
If earth attachment is not provided for the diaphragm, then the structure is simpler, but interference signals cannot be avoided
Solution Approach 1:
The earth attachment for the diaphragm is extracted as a separate, independent electrical connection from the piezo-electric element's connection. This separate earth path allows interference signals on the diaphragm to be independently grounded, preventing them from affecting signal reception without complicating the overall structure.
Solution Approach 2:
By providing an earth attachment for the diaphragm, the diaphragm is maintained at earth potential, creating an equipotential reference that prevents voltage differences and associated interference signals. This simple structural addition effectively rejects interference without requiring complex shielding or filtering.
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 simplifies manufacturing, enhances quality by reducing interference signals, and improves signal reception, resulting in a more reliable and cost-effective ultrasonic sensor.
Implementation Method 1
A piezo-electric vibrator is fastened to an inner face of the bottom section
Implementation Method 2
characterized in that the piezo-electric element is provided with a non-conducting layer on an electrode
Implementation Method 3
The piezo-electric element is preferably fastened with its paint layer to the diaphragm by means of an adhesive
Implementation Method 4
The ultrasonic sensors emit ultrasonic signals and receive signals which are reflected on obstacles
Data Source
AI summary
An ultrasonic sensor (1) comprises a housing (2) and a diaphragm (4), to which a piezo-electric element (6) is fastened, and an electric connector region (8) which has an earth connector (24). A layer made from an electrically non-conducting material is arranged between the diaphragm (4) and the piezo-electric element (6), and the diaphragm (4) is connected to the earth connector (24) in an electrically conducting manner.