Ultrasonic Tool Galvanic Isolation for Safe Contact Detection
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Solution Overview
Problem
Ultrasonic tools face safety challenges due to the risk of electrical faults and the inability to ground the converter housing, which can lead to occupational hazards and hinder contact detection between the sonotrode and counter tool.
Innovation Solution
The ultrasonic tool incorporates galvanic isolation between the neutral conductor and the sealing surface of the sonotrode, preventing potential dissipation and allowing for additional grounding of the converter housing, while maintaining effective contact detection through a signal terminal isolated from the neutral conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the converter housing is grounded by means of a protective conductor to improve occupational safety, then safety against electrical faults is improved, but contact detection between sonotrode and counter tool becomes impossible
Solution Approach 1:
The electrical system is segmented into two independent parts: the power supply circuit (phase and neutral conductors) and the signal detection circuit (signal conductor). This segmentation allows the converter housing to be grounded for safety while maintaining the ability to detect contact through the isolated signal circuit.
Solution Approach 2:
A signal terminal and signal conductor act as intermediaries between the sonotrode and the control device. These intermediaries enable contact detection without requiring the converter housing to be isolated, thus resolving the contradiction between grounding for safety and contact detection capability.
2Stability of the object's composition
If the neutral conductor is connected to the converter housing to provide a reference potential, then electrical stability is improved, but high potentials can be transferred to the sonotrode in case of fault
Solution Approach 1:
The electrical system is divided into power supply conductors (phase and neutral) and signal conductors. The neutral conductor is connected to the converter housing for stability, but the signal terminal provides an additional reference that prevents potential transfer to the sonotrode by maintaining electrical isolation through the galvanic isolation interface.
Solution Approach 2:
The signal terminal serves as an intermediary that provides a safe reference potential for contact detection without creating a direct electrical path that could transfer harmful potentials to the sonotrode. This mediator enables both electrical stability and safety simultaneously.
3Reliability
If extensive insulation of piezoelements in converter housing is implemented to ensure safety, then occupational safety is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The safety function is extracted from the converter housing insulation and implemented through the signal terminal and galvanic isolation interface. This extraction eliminates the need for extensive insulation of piezoelements while maintaining safety, as the signal terminal provides the necessary electrical isolation for contact detection.
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 solution enhances occupational safety by preventing the transfer of high potentials to the sonotrode and counter tool, enabling reliable contact detection and grounding without compromising the ultrasonic oscillation process.
Implementation Method 1
The converter member comprises a converter, which typically comprises several piezoelements and converts the applied electric AC voltage, which is generally provided by a generator, into a mechanical movement of the same frequency. Each piezoelement is connected to a phase conductor of the generator on the one hand and to a neutral conductor of the generator on the other hand. If an AC voltage is applied to these conductors, the piezoelements alternately become longer and shorter, thus generating an ultrasonic oscillation.
Implementation Method 2
The converter member can be set into a resonance oscillation with a mechanically ultrasonic oscillation of the wavelength A and is mechanically coupled to the sonotrode. The sonotrode and the converter member are tuned to one another such that the sonotrode can set into resonance oscillation with the mechanical ultrasonic oscillation of the wavelength λ.
Implementation Method 3
The sealing surface of the sonotrode and the neutral conductor are galvanically isolated. In the event of a fault, there can be a potential on the neutral conductor that is not dissipated. The galvanic isolation prevents this potential from being transferred to the sealing surface.
Data Source
AI summary
Ultrasonic tool and method for machining a workpiece by means of mechanical ultrasonic oscillations.