Inductive Proximity Sensor Pulse Control for High Switching Frequency
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Solution Overview
Problem
Inductive proximity sensors face limitations in achieving high switching frequencies due to extended response pulses when objects are close, leading to potential eddy current accumulation and altered switching thresholds.
Innovation Solution
The sensor employs a control and evaluation unit to scan induced voltage and current pulses in multiple sections, ending the transmitted current pulse early if a long response is expected, and adjusts pulse length based on current rise, using multiple coils and digital integration to optimize signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the time duration between two excitation pulses is increased to allow full abatement of extended response pulses when objects are close, then the switching frequency of the inductive sensor is reduced, but the response pulse can fully abate without accumulation
Solution Approach 1:
The patent applies dynamics by making the excitation pulse duration adaptive rather than fixed. The control unit dynamically adjusts the duration of excitation pulses based on detected object distance - using shorter pulses for close objects and longer pulses for distant objects. This dynamic adjustment allows the system to maintain high switching frequencies for close objects while ensuring adequate pulse abatement for distant objects, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent changes the parameter of excitation pulse duration based on object distance conditions. By monitoring the response signal characteristics and adjusting the pulse duration parameter accordingly, the system optimizes both the abatement completeness and switching frequency. This parameter adaptation allows the sensor to operate at maximum switching frequency when objects are close while maintaining reliable detection when objects are farther away.
2Reliability
If the excitation is delayed until the received signal has abated to prevent eddy current accumulation, then the switching frequency is limited, but eddy current accumulation and changes to switching threshold are prevented
Solution Approach 1:
The patent applies preliminary action by proactively adjusting the excitation pulse duration before eddy current accumulation can occur. Instead of waiting for signal abatement and then delaying excitation (which limits frequency), the system preemptively uses shorter pulse durations for close objects, ensuring that eddy currents do not have time to accumulate while maintaining continuous high-frequency operation.
3Reliability
If the distance of consecutive excitation pulses is selected to allow full abatement of response pulses at all object distances, then the switching frequency is reduced to a safe level, but the response pulse can fully abate even when objects are close
Solution Approach 1:
The system transitions from static, conservative pulse timing to dynamic, adaptive pulse timing. The control unit continuously monitors object distance and adjusts excitation pulse duration in real-time, enabling the system to operate at high switching frequencies for close objects while maintaining adequate abatement for distant objects through shorter pulses.
Solution Approach 2:
The patent applies partial action by using just enough pulse duration for each specific condition rather than a uniformly excessive duration. For close objects, shorter pulses are used (partial action sufficient for abatement), while for distant objects, longer pulses are used when needed. This eliminates the need for conservative timing that would limit switching frequency across all conditions.
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 approach allows for maximizing switching frequency without coil current alteration, improving signal-to-noise ratio and enabling precise material identification and distance measurement.
Implementation Method 1
inductive proximity sensor for the detection of an object having at least one coil (3), wherein at least one transmitted current pulse (5) can be applied to the coil (3)
Implementation Method 2
an accumulation of the eddies in the target can arise
Implementation Method 3
scan at least one induced voltage pulse (6) that has been generated by the transmitted current pulse (5) at the coil (3)
Data Source
AI summary
An inductive proximity sensor and a method for the detection of an object having at least one coil, wherein at least one transmitted current pulse can be applied to the coil by a control and evaluation unit and the control and evaluation unit is configured to output an object determination signal, wherein the control and evaluation unit is configured to scan at least one induced voltage pulse that has been generated by the transmitted current pulse at the coil in a plurality of sections from or after the time of the application of the transmitted current pulse and to form scan values, whereby the voltage pulse is digitized, wherein the control and evaluation unit is configured to evaluate the scan values for an object detection of a metallic object, wherein the control and evaluation unit is configured to scan the transmitted current pulse that has been generated at the coil in at least two sections from or after the time of the application of the transmitted current pulse and to form transmitted current scan values, wherein the control and evaluation unit is configured to determine a rise in the current increase of the transmitted current pulse from the transmitted current scan values, and the control and evaluation unit is configured to end the transmitted current pulse in dependence on the detected increase of the transmitted current pulse.