Magnetic Actuator Armature Stroke Determination

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Solution Overview

Problem

Existing methods for determining the armature stroke of magnetic actuators, such as those used in diesel injection valves or fuel injectors, are inefficient and require multiple hysteresis curves to determine setpoint deviations, making them cumbersome and not suitable for continuous monitoring.

Innovation Solution

A method that determines the armature stroke by generating a magnetic hysteresis curve, selecting a curve section representing the armature's transition between stationary end positions, simulating the armature's energy state, and comparing energy profiles to calculate the armature stroke using polynomial interpolation and integration, allowing for continuous monitoring and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple hysteresis curves are recorded to determine setpoint deviation, then the armature stroke can be determined, but the measurement and computational effort increases significantly

Engineering Contradiction:
Improvearmature stroke determinationVSAvoidmeasurement and computational effort
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential information needed for armature stroke determination by identifying and analyzing specific curve segments within a single hysteresis curve, rather than requiring multiple complete hysteresis curves. This extraction approach focuses on the critical transition regions where the armature moves between end positions, obtaining sufficient measurement data with minimal effort.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies preliminary action by generating a simulated curve segment that represents the ideal hysteresis behavior with the armature fixed in its first end position. This simulated reference is created in advance and used for comparison with the actual measured curve segment, enabling direct determination of setpoint deviation and armature stroke without requiring multiple measurements.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If two different hysteresis curves are recorded to determine closing movement, then the setpoint deviation can be calculated, but the process becomes cumbersome and unsuitable for continuous monitoring

Engineering Contradiction:
Improvesetpoint deviationVSAvoidcontinuous monitoring capability
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent merges the determination of both opening and closing movements into a single hysteresis curve analysis. By identifying and comparing curve segments from the same hysteresis loop, the method simultaneously obtains setpoint deviation information for both movement directions, eliminating the need for separate measurements and enabling continuous monitoring.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent applies partial action by recording only the essential portions of the hysteresis curve that contain information about armature movement transitions. Instead of requiring complete multiple hysteresis cycles, the method focuses on analyzing specific curve segments within a single cycle, reducing measurement time and computational requirements while maintaining accuracy.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If the armature stroke is not monitored, then the system operates without additional measurement equipment, but performance degradation due to wear or malfunction goes undetected

Engineering Contradiction:
Improveinjection system performanceVSAvoidmeasurement and evaluation equipment
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements self-service by using the magnetic actuator's own hysteresis characteristics as the measurement basis. The existing magnetic properties and hysteresis behavior of the actuator are utilized to monitor its own armature stroke and detect performance degradation, eliminating the need for separate external measurement systems while maintaining reliability.

Inventive Principle:
Principle #25Self-service

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 efficient determination and continuous monitoring of the armature stroke with reduced measurement and calculation overhead, effectively managing the performance of injection systems by accurately measuring the armature lift.

Implementation Method 1

the line-linked magnetic flux ψ is measured as a function of the current I through a coil of the magnetic actuator. The line-linked magnetic flux is proportional to the integral ∫U ind dt and can be determined relatively easily by measuring the voltage induced in a measuring coil of the magnetic actuator and subsequently integrating it over time.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

determining a magnetic hysteresis curve of the magnetic actuator, selecting a curve segment in the magnetic hysteresis curve characterized by a transition of the armature from a first stationary end position to a second stationary end position

Methodology Applied
Scientific EffectMagnetic hysteresis: Magnetic Hysteresis

Data Source

PatentEP3224465B1Method for determining the armature stroke of a magnetic actuator
Publication Date: 2019.10.16 ROBERT BOSCH GMBH
  • EP3224465B1 patent drawingFigure 1
  • EP3224465B1 patent drawingFigure 2
  • EP3224465B1 patent drawingFigure 3A~3B

AI summary

The invention relates to a method for determining the armature stroke of a magnetic actuator which has at least one air gap and one armature, comprising the method steps: determining of a magnetic hysteresis curve (10) of the magnetic actuator, selecting of a curve region (20) in the magnetic hysteresis curve (10) which is characterised by a transition of the armature from a first stationary end position into a second stationary end position, determining of the magnetic energy state of the magnetic actuator in the second stationary end position of the armature on the basis of the profile of the selected curve region (20), producing of a curve region (22) in the interval of the selected curve region (20), wherein the produced curve region (22) simulates the magnetic actuator with the armature fixed in the first end position thereof, in order to determine a magnetic energy state of the magnetic actuator which corresponds thereto, and comparing of the two energy states of the magnetic actuator on the basis of the profiles of the selected curve region (20) and of the produced curve region (20) in order to determine the armature stroke on the basis thereof.