Resonant Circuit Tool Conductor Contact Detection
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Solution Overview
Problem
Existing methods for detecting contact between a tool and an electrical conductor, especially in cable stripping machines, are limited in reliability and accuracy, particularly for short and potential-free cable lengths, and often require electrical contact with the conductor or are ineffective for varying cable lengths.
Innovation Solution
A device utilizing a parallel resonant circuit with an inductance connected between the tool and tool holder, allowing detection of changes in characteristic oscillation parameters without direct electrical contact with the conductor, and featuring a circuit arrangement with a frequency generator, phase detector, and optional output capacitor for increased sensitivity and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple current detection method is used (applying voltage and detecting current flow), then device complexity is reduced, but measurement precision and reliability deteriorate because it cannot reliably detect contact for short and potential-free cable lengths
Solution Approach 1:
The patent replaces simple electrical current detection with a resonant circuit-based detection system. Instead of directly detecting current flow through the conductor, the system uses an LC resonant circuit where the tool and conductor form one plate capacitor and the tool holder forms another. Contact between the tool and conductor changes the capacitance of this resonant circuit, which can be detected through frequency or phase changes, providing much higher precision for short and potential-free cables.
Solution Approach 2:
The patent changes the detection parameter from direct current measurement to resonant frequency measurement. By monitoring the resonant frequency of the LC circuit formed by the tool, tool holder, and conductor, the system can detect contact with high precision. The capacitance change caused by contact alters the resonant frequency, which is measured by the evaluation device to determine contact occurrence.
2Measurement precision
If capacitive coupling method is used (passing cable through pipe sections with high-frequency voltage), then contact detection capability is improved, but device complexity increases and it is only effective for relatively short cables
Solution Approach 1:
The patent makes the detection system universal by using the existing structural components (tool, tool holder, and conductor) to form the detection circuit itself. Instead of requiring separate pipe sections or external coupling devices, the system uses the functional elements already present in the cable stripping machine. This eliminates the need for additional specialized hardware while maintaining high detection capability for various cable lengths.
Solution Approach 2:
The patent merges the functional elements (tool, tool holder, conductor) with the detection circuit. The tool and conductor form one plate capacitor, the tool holder forms the other plate capacitor, and the insulation between them forms the capacitor dielectric. This integration eliminates the need for separate detection hardware and simplifies the overall system while improving detection precision.
3Measurement precision
If inductive coupling method is used (torus coil and tubing for voltage coupling), then contact detection is improved for long cables, but device complexity increases and it is only applicable to one side of the insulation stripping process
Solution Approach 1:
The patent creates a universal detection system that can be applied at any position in the insulation stripping process. By using the tool and tool holder themselves as part of the resonant circuit, the system works regardless of whether the stripping is performed from the left or right side of the cable. This eliminates the limitation of one-sided applicability while maintaining high detection precision.
4Measurement precision
If ohmic voltage coupling method is used (connecting wire stripper to high-frequency voltage source via resistor), then contact detection is achieved, but device complexity increases and sensitivity is unfavorable for short cables due to knife's own capacitance
Solution Approach 1:
The patent combines the functional elements (tool, conductor, tool holder) to form the detection circuit itself. The tool and conductor form one plate capacitor, the tool holder forms the other, and the insulation between them is the dielectric. This merging eliminates the need for external resistors, voltage sources, and separate coupling components, significantly reducing device complexity while improving sensitivity for short cables.
Solution Approach 2:
The system uses the inherent electrical properties of the existing components (capacitance between tool and tool holder through insulation) to perform detection. No external power source or additional components are needed - the system self-generates the detection signal through the resonant circuit formed by its own structural elements, eliminating the complexity of external coupling circuits.
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
Enables reliable and robust detection of tool-conductor contact across various cable lengths, including short and potential-free cables, with minimal electronics, ensuring quality control and reduced risk of conductor damage.
Implementation Method 1
an inductor L is electrically connected between the tool (2a, 2b) and the tool holder (1a, 1b), such that the tool (2a, 2b) and the tool holder (1a, 1b) form parts of a parallel resonant circuit
Implementation Method 2
the tool (2a, 2b) and the tool holder (1a, 1b) form parts of a parallel resonant circuit... the tool and the tool holder are made of electrically conductive material and are electrically insulated from one another by a thin electrical insulation (5a)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a device for detecting the contact of a tool (2a, 2b) with an electrical conductor (5b) enclosed by an electrical insulation (5a). In order to ensure a reliable, robust, and simple indication of the tool/conductor contact even for potential-free and short cable lengths, the tool (2a, 2b), which is made of electrically conductive material, is fastened to a tool retainer (1a, 1b) made of electrically conductive material. A thin electrical insulation is provided between the tool (2a, 2b) and the tool retainer (1a, 1b) such that said components form a capacitor (CS) together with the coaxial cable. An inductor (La, Lb) is connected in parallel therewith such that an LC oscillating circuit of high quality is formed between the tool and the tool retainer. The electronic circuit assembly excites the oscillating circuit and determines characteristic oscillation parameters of said oscillating circuit. Furthermore, for the cable processing, tool/conductor contacts can be weighted in dependence on contact duration and point in time within the cable-processing process, and thus quantitative production rejection criteria can be determined.