Inductive Sensor on Threaded Spindle for Clutch Actuator

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Solution Overview

Problem

Existing clutch actuation systems with electric motor-actuated transmissions face challenges in reducing installation space while reliably determining the axial path covered by the piston, often requiring separate sensor targets that increase cost and space usage.

Innovation Solution

The method utilizes the metal threaded spindle as a sensor target connected to an inductive sensor device, eliminating the need for a separate sensor target by using the spindle's metallic material to determine the axial position, with a coil and evaluation circuit to measure inductance changes, and a rotor position sensor for plausibility checks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a separate sensor target is used for inductive measurement, then reliable piston position determination is achieved, but installation space increases and production cost increases

Engineering Contradiction:

Improvepiston position determinationVSAvoidinstallation space

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent merges the sensor target function with the threaded spindle by using the spindle's metallic material properties for inductive measurement. The threaded spindle serves dual purposes: mechanical transmission and sensor target, eliminating the need for separate sensor targets and reducing installation space.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The threaded spindle is designed to perform multiple functions simultaneously: it acts as both the mechanical transmission component for clutch actuation and the sensor target for inductive position measurement. This multi-functionality reduces the overall component count and installation space.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If a separate sensor target is used for inductive measurement, then reliable piston position determination is achieved, but production cost increases

Engineering Contradiction:

Improvepiston position determinationVSAvoidproduction cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent combines the sensor target functionality into the existing threaded spindle, eliminating the need for separate sensor target components. This reduces part count, simplifies manufacturing, and lowers production costs while maintaining measurement precision.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The threaded spindle's metallic material properties are utilized to provide the sensor target function inherently. The spindle serves itself as the measurement target, eliminating the need for additional components and reducing manufacturing complexity.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If external displacement sensor and magnets are used, then piston displacement is determined, but installation space increases significantly

Engineering Contradiction:

Improvepiston displacement measurementVSAvoidactuator installation space

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent extracts the magnetic components (magnets and external sensors) from the measurement system and replaces them with an inductive measurement approach using the metallic threaded spindle. This eliminates the need for bulky magnetic components and reduces installation space.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the magnetic measurement system with an inductive measurement system that utilizes the metallic properties of the threaded spindle. This substitution reduces the physical space required for sensor components while maintaining measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces installation space, provides reliable piston position determination, and is robust against external influences, ensuring accurate measurements without measurement errors from tilting or external dynamics.

Implementation Method 1

the inductive sensor device (6) is in an operative connection with the metal threaded spindle (4) connected to the piston (5), the metal threaded spindle (4) being used as a sensor target for determining the axial path

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3619445B1Method for operating an actuator arrangement for a clutch operating system, and actuator arrangement

Publication Date: 2021.11.24 SCHAEFFLER TECHNOLOGIES AG & CO KG

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AI summary

The invention relates to a method for operating an actuator arrangement for a clutch operating system which comprises an electromotively operated transmission (2) with a threaded spindle (4) which converts a rotational movement into a linear movement of a piston (5) in the axial direction, wherein an axial distance which is covered by the piston (5) is ascertained using a sensor device (6, 10). In a method in which the installation space of the actuator arrangement is reduced, the inductive sensor device (6, 10) is operatively connected to the metal threaded spindle (4) which is connected to the piston (5), wherein the metal threaded spindle (4) is used as a sensor target for determining the axial distance.