Clutch Slave Cylinder Encoder Layout for Accurate Piston Sensing

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Solution Overview

Problem

Existing slave cylinder designs for clutch actuation in motor vehicles face issues with compactness and durability due to unintentional rotation of the transmitter part, leading to incorrect position detection and increased wear on the seal, which can be exacerbated by larger master parts to counteract displacement.

Innovation Solution

The transmitter part is guided in a groove within the housing along the piston's displacement path, allowing it to rotate freely, reducing wear on the seal and enabling a more compact design by securing it firmly in the axial direction while allowing circumferential movement, thus simplifying assembly and reducing installation space requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the transmitter part is secured against rotation during operation, then position detection accuracy is improved, but the seal experiences greater wear due to restricted piston movement

Engineering Contradiction:
Improveposition detection accuracyVSAvoidseal durability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The transmitter part is designed to rotate together with the piston during operation, creating a dynamic connection that accommodates piston movement. This rotational freedom eliminates excessive friction and wear on the seal while maintaining accurate position detection through the magnet's movement relative to the sensor

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If the master part is made larger to prevent unintentional displacement, then position detection accuracy is improved, but the slave cylinder size increases

Engineering Contradiction:
Improveposition detection accuracyVSAvoidslave cylinder size
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The mechanical connection between the master part and transmitter part is replaced with a magnetic field-based detection system. A magnet in the transmitter part generates a magnetic field that is detected by a sensor in the housing, eliminating the need for large mechanical coupling components and enabling compact slave cylinder design

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the transmitter part is freely rotatable relative to the piston, then seal wear is reduced, but position detection accuracy deteriorates due to rotational instability

Engineering Contradiction:
Improveseal durabilityVSAvoidposition detection accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The transmitter part is designed to rotate together with the piston during operation, creating a dynamic connection that accommodates piston movement. This rotational freedom eliminates excessive friction and wear on the seal while maintaining accurate position detection through the magnet's movement relative to the sensor

Inventive Principle:
Principle #15Dynamics

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 the compactness and durability of the slave cylinder by improving position detection accuracy and reducing seal wear, allowing for a more efficient and reliable clutch actuation system.

Implementation Method 1

the transmitter part (7) has at least one magnet (16)

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP3759370B1Slave cylinder having encoder part connection in the piston; actuating device and clutch system
Publication Date: 2023.04.05 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3759370B1 patent drawingFigure 1~2
  • EP3759370B1 patent drawingFigure 3~4
  • EP3759370B1 patent drawingFigure 5~7

AI summary

The invention relates to a slave cylinder (1) for a clutch actuating device of a motor vehicle, having a housing (2), a piston (4), which is movably received in the housing (2) and, together with the housing (2), delimits a fluidic pressure chamber (3), wherein the piston (4) has a seal (5), which seals the pressure chamber (3) from an environment, and having a sensor device (6), designed to detect a position of the piston (4) along the displacement path thereof, wherein an encoder part (7) of the sensor device (6) is received on the piston (4) in a fixed manner, wherein the encoder part (7) is guided in a guide track (8), which is formed in the housing (2), along the displacement path of the piston (4) relative to the housing (2). The invention additionally relates to an actuating device having said slave cylinder (1) and to a clutch system.