Master Cylinder Sensor Assembly Integrating Travel and Vacuum Detection

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Solution Overview

Problem

Existing automotive braking systems face challenges with high costs associated with vacuum sensors and the need for additional travel sensors to determine brake pedal travel, which require dedicated assembly and wiring solutions.

Innovation Solution

A sensor assembly for the master cylinder that includes a displacement sensor for detecting pedal travel, a position sensor for determining when a predetermined position is reached, and a circuit device for calibrating the displacement sensor using the position sensor's output signal, potentially eliminating the need for a separate vacuum sensor and simplifying sensor installation by integrating sensors into a single housing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a vacuum sensor is installed in the master cylinder to detect vacuum levels, then the functionality for determining brake booster vacuum is improved, but the manufacturing cost and device complexity increase significantly

Engineering Contradiction:
Improvevacuum detection capabilityVSAvoidsensor assembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the vacuum sensing function from a dedicated vacuum sensor and implements it through the existing position sensor by detecting the position of a diaphragm that responds to vacuum changes. This eliminates the need for a separate vacuum sensor while maintaining vacuum detection capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The position sensor is designed to serve multiple functions: detecting the position of the actuating element for brake light switch operation and simultaneously detecting vacuum levels through the diaphragm's position changes. This multi-functionality reduces the number of sensors required.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If a separate travel sensor is installed to determine brake pedal travel, then the measurement accuracy is improved, but the assembly complexity and wiring requirements increase

Engineering Contradiction:
Improvepedal travel measurement accuracyVSAvoidsensor installation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the displacement sensor and position sensor into a single integrated sensor assembly housed together. This merging reduces the number of separate components, simplifies installation, and eliminates the need for separate wiring harnesses for each sensor.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

A magnetic coupling mechanism serves as an intermediary between the actuating element and the sensors, allowing non-contact detection of both position and travel information through magnetic field interactions, thereby simplifying the mechanical connection requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If multiple sensors are installed in the master cylinder, then the functionality for detecting pressure, position, and vacuum is improved, but the cost and assembly complexity increase

Engineering Contradiction:
Improvedetection functionalityVSAvoidassembly simplicity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges multiple sensing functions (position detection, travel measurement, and vacuum sensing) into a single integrated sensor assembly containing both displacement and position sensors that work together to provide comprehensive detection capabilities.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The sensor assembly is designed to provide multiple detection functions simultaneously: the position sensor detects both actuating element position and vacuum levels through diaphragm movement, while the displacement sensor measures pedal travel, making the assembly universally applicable for multiple monitoring needs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 reduces costs by potentially eliminating the vacuum sensor and simplifies sensor installation, while providing accurate and reliable determination of brake pedal travel and vacuum in the brake booster, thereby enhancing the efficiency of the braking system.

Implementation Method 1

a magnet element is arranged on a piston inside a brake cylinder housing, which magnetic element interacts with a sensor element arranged outside the brake cylinder housing in order to detect the position and movement of the piston

Methodology Applied
Scientific EffectMagnetic flux density sensing: Magnetic Field

Implementation Method 2

an actuation detection device is arranged outside of the brake cylinder housing, which sensor interacts with the magnetic element in order to detect the start of an actuation of the piston

Methodology Applied
Scientific EffectMagnetic flux density sensing: Magnetic Field

Data Source

PatentEP2593334B1Sensor assembly for a master cylinder
Publication Date: 2018.05.09 ZF ACTIVE SAFETY GMBH
  • EP2593334B1 patent drawingFigure 1
  • EP2593334B1 patent drawingFigure 2~3
  • EP2593334B1 patent drawingFigure 4~5

AI summary

A sensor assembly for use with a master cylinder is described. The master cylinder comprises an input-side activation element to which a signal transmitter element is coupled. The sensor module comprises a travel sensor (56) for sensing travel carried out by the activation element, and a position sensor (90) for sensing when a predefined position of the activation element is reached.