Motor Vehicle Brake Self-Locking Device Gear Arrangement

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Solution Overview

Problem

Existing motor vehicle brakes with self-locking mechanisms for parking brake functionality suffer from low efficiency and require strong, high-current components due to the self-locking gear arrangements, leading to large dimensions and high power consumption.

Innovation Solution

The self-locking device is integrated into or arranged within the gear arrangement, with at least two gear stages between the ball screw and the self-locking device, allowing the gear stages to reduce reaction forces and enabling a more compact design with improved efficiency by eliminating the need for self-locking components in the gear arrangement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a self-locking gear arrangement is used in the displacement mechanism, then the parking brake function can be maintained reliably, but the efficiency of power transmission drops to 30% or less and high current consumption is required

Engineering Contradiction:
Improveparking brake maintenanceVSAvoidpower transmission efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The displacement mechanism is divided into two independent parts: a gear arrangement for power transmission and a separate self-locking device for maintaining the parking brake function. This segmentation allows each component to be optimized for its specific function, with the gear arrangement achieving high efficiency and the self-locking device providing reliable locking without energy losses.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The self-locking device acts as an intermediary between the displacement mechanism and the brake pads. It receives the braking force from the displacement mechanism and maintains the parking brake function independently, allowing the gear arrangement to operate without the energy losses associated with self-locking mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the self-locking device is arranged directly on the nut-spindle arrangement, then self-locking functionality is achieved, but the device becomes massive and occupies considerable space

Engineering Contradiction:
Improveself-locking functionalityVSAvoidbrake assembly size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The self-locking function is extracted from the nut-spindle arrangement and placed in a separate self-locking device within the gear arrangement. This extraction allows the self-locking mechanism to be designed independently and integrated into the existing brake structure without requiring a massive design directly on the nut-spindle arrangement.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The self-locking device is merged with the gear arrangement, combining the self-locking functionality with the existing power transmission components. This integration allows the self-locking device to utilize the space and structure already present in the gear arrangement, avoiding the need for additional space-consuming components.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If self-locking gear arrangements are used, then parking brake reliability is ensured, but the motor drive must be designed to be strong with high current consumption

Engineering Contradiction:
Improveparking brake activationVSAvoidmotor drive strength
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The system is segmented into a high-efficiency gear arrangement for power transmission and a separate self-locking device for maintaining the brake function. This segmentation eliminates the energy losses in the power transmission path, allowing the motor drive to be smaller and consume less current while still achieving reliable parking brake activation.

Inventive Principle:
Principle #1Segmentation

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 configuration achieves efficiencies of over 50% in power transmission, allowing for a smaller, weaker motor drive with lower power consumption and reduced component size, while maintaining reliable self-locking functionality.

Implementation Method 1

The displacement mechanism has a ball screw drive with a spindle and a nut, one component of the spindle and nut being rotatably drivable and the respective other component of the spindle and nut being linearly displaceable for displacement of the actuator by rotating one component of the spindle and nut within the housing

Methodology Applied
Scientific EffectScrew mechanism: Screw

Implementation Method 2

the gear arrangement has at least two gear stages

Methodology Applied
Scientific EffectGear mechanism: Gear

Implementation Method 3

a separate self-locking device that is designed to block the shifting mechanics if necessary

Methodology Applied
Scientific EffectFriction locking: Friction

Data Source

PatentEP3444156B1Motor vehicle brake with self-locking device
Publication Date: 2021.12.08 ZF ACTIVE SAFETY GMBH
  • EP3444156B1 patent drawingFigure 1
  • EP3444156B1 patent drawingFigure 2
  • EP3444156B1 patent drawingFigure 3

AI summary

The invention relates to a motor vehicle brake, in particular a combined hydraulically and electromechanically actuated motor vehicle brake, with an actuator assembly (A) comprising: - a housing (AG, BG), - an actuator (BK) displaceable relative to the housing (AG, BG) for hydraulically or electromechanically displacing a brake pad, - a motor drive (EM), - a displacement mechanism arranged between the motor drive (EM) and the displaceable actuator (BK), - a gear arrangement (GS1, GS2, GS3) associated with the displacement mechanism, and - a separate self-locking device (SHV) configured to block the displacement mechanism when required, wherein the displacement mechanism comprises a ball screw drive (SM) with a rotatable spindle and a nut linearly displaceable in the housing (BG).wherein the nut for relocating the actuator (BK) can be relocated within the housing (BG) by rotating the spindle, and wherein the gear assembly has at least two gear stages (GS1, GS2, GS3). In this motor vehicle brake, it is provided that the self-locking device (SHV) is arranged in or on the gear assembly (GS1, GS2, GS3) such that at least two gear stages (GS2, GS3) are arranged between the ball screw drive (SM) and the self-locking device (SHV).