Vehicle Brake System Parking Release Control

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Solution Overview

Problem

Existing vehicle brake systems experience abrupt release of the parking brake function when the self-locking mechanism is overcome, leading to discomfort and potential vehicle acceleration issues, especially when starting off downhill.

Innovation Solution

The control device actuates hydraulic functional elements to isolate and lock in hydraulic fluid volume in the disc brake device, allowing for a controlled reduction in hydraulic pressure during parking brake release, preventing abrupt release by maintaining hydraulic tension and enabling gradual release based on specific characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the self-locking mechanism is overcome by applying actuating force to release the parking brake, then the parking brake function is released, but the release occurs abruptly causing discomfort and potential vehicle acceleration issues

Engineering Contradiction:
ImproveParking brake releaseVSAvoidAbrupt release causing discomfort and vehicle acceleration
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary action by isolating the hydraulic fluid volume before releasing the self-locking mechanism. This preliminary isolation of hydraulic fluid creates a controlled environment that prevents abrupt pressure changes when the parking brake is released, thereby avoiding discomfort and unintended vehicle acceleration.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the parameter of hydraulic pressure by controlling the reduction of pressure in the isolated fluid volume. By managing the pressure reduction rate, the system ensures a controlled and gradual release of the parking brake, preventing abrupt releases that would cause discomfort or vehicle movement.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If hydraulic pressure is reduced quickly to release the parking brake, then the release process is fast, but the release becomes abrupt causing discomfort

Engineering Contradiction:
ImproveParking brake release speedVSAvoidAbrupt release causing discomfort
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system controls the rate of pressure reduction in the isolated hydraulic fluid volume. By adjusting this parameter, the system achieves a balance between release speed and comfort, ensuring the parking brake releases efficiently without causing abrupt movements or driver discomfort.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system isolates the hydraulic fluid volume as a preliminary step before reducing pressure. This isolation allows the system to control the pressure reduction process independently, enabling fast yet controlled release that maintains comfort by preventing abrupt pressure changes.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If the electromechanical actuating device directly releases the self-locking mechanism, then the release is simple, but it causes strong acceleration when starting downhill

Engineering Contradiction:
ImproveRelease mechanismVSAvoidStrong acceleration on downhill
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The system introduces an intermediary step by isolating the hydraulic fluid volume between the actuating device and the brake mechanism. This intermediary isolation of hydraulic fluid acts as a buffer that controls the release process, preventing direct and abrupt release that would cause strong acceleration on downhill starts.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary isolation of hydraulic fluid before the actuating device releases the self-locking mechanism. This preliminary action creates a controlled environment that mitigates the harmful effect of strong acceleration on downhill starts while maintaining the simplicity of the electromechanical release mechanism.

Inventive Principle:
Principle #10Preliminary action

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 method prevents abrupt release of the parking brake function, ensuring a gentle and controlled release that avoids sudden vehicle acceleration, enhancing comfort and safety, especially during downhill starts.

Implementation Method 1

a volume of hydraulic fluid present in the disc brake devices can be isolated or locked in and the hydraulic pressure can then be reduced in accordance with a predetermined or variable characteristic

Methodology Applied
Scientific EffectHydraulic pressure: Pascal's Law

Implementation Method 2

an electromechanical actuating device for activating a parking brake function

Methodology Applied
Scientific EffectElectromechanical conversion: Electromagnetic Induction

Implementation Method 3

a hydraulic circuit with a hydraulic pressure source and controllable hydraulic functional elements in order to hydraulically activate the disc brake device

Methodology Applied
Scientific EffectHydraulic transmission: Pascal's Law

Data Source

PatentEP2601085B1Vehicle brake system for a motor vehicle and method for actuating the vehicle brake system during release of the parking brake function
Publication Date: 2014.10.29 ZF ACTIVE SAFETY GMBH
  • EP2601085B1 patent drawingFigure 1
  • EP2601085B1 patent drawingFigure 2
  • EP2601085B1 patent drawingFigure 3

AI summary

The invention relates to a vehicle brake system (100) having a hydraulically actuable disc brake device (10) which has an electromechanical actuating device (34) for activating a parking brake function, wherein the vehicle brake system (100) has a hydraulic circuit (112) with a hydraulic pressure source (102) and actuable hydraulic functional elements (114, 120, 122, 124, 126), in order to hydraulically actuate the disc brake device (10) in accordance with a service brake action of a driver or an automatic activation of a driving assistance system, wherein, furthermore, the vehicle brake system (100) has a control device, in order to actuate the electromechanical actuating device (34) in accordance with a parking brake action of the driver or an automatic activation of the parking brake function. In order to avoid abrupt release of the parking brake function, it is provided here that the control device is configured for actuating at least one of the hydraulic functional elements (128) in such a way that, in order to release the parking brake function, a hydraulic fluid volume is isolated in the disc brake device (10) by actuation of the electromechanical actuating device (34) and said hydraulic fluid volume can be used to generate a predefined hydraulic pressure hydraulically during the release of the parking brake function by means of the electromechanical actuating device.