Vehicle Braking System Cable Sheath Friction Force Distribution

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Solution Overview

Problem

Current combined braking systems for motor vehicles are complex and prone to imprecision due to mechanical clearances and connections, leading to unstable vehicle stability during sudden braking, as they rely on hydraulic members that can be unreliable.

Innovation Solution

A braking system where a transmission cable housed in a deformable sheath with a curved portion transmits force from the rear brake control member to both the front and rear brakes, eliminating the need for complex hydraulic distribution members by leveraging friction between the cable and sheath to activate both brakes effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hydraulic member with linkages and control cables is used to distribute braking force, then the braking force can be distributed between front and rear brakes, but the system becomes complex and imprecise due to mechanical clearances and connection failures

Engineering Contradiction:
Improvebraking system reliabilityVSAvoidhydraulic member complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the complex hydraulic distribution member from the system entirely. Instead of using a hydraulic member with linkages and multiple connections, the invention extracts this component and replaces it with a direct mechanical cable-pulley arrangement, eliminating the source of mechanical clearances and connection failures.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The transmission cable serves multiple functions: it actuates the rear brake directly and, through the pulley mechanism, simultaneously actuates the front brake. This multi-functionality eliminates the need for separate hydraulic distribution components while maintaining effective braking force distribution.

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

2Productivity

If the rear brake is actuated with sufficient force, then the vehicle can stop within expected time/space, but the front wheel may stop or the vehicle may noise up, causing discomfort and hazard

Engineering Contradiction:
Improvebraking efficiencyVSAvoidvehicle stability
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The pulley mechanism provides automatic feedback-based force distribution. As the rear brake is actuated and creates resistance, the pulley system automatically adjusts the force distribution to the front brake, ensuring optimal braking balance without rider intervention. This prevents front wheel lockup while maintaining stopping efficiency.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts braking force distribution between front and rear brakes during actuation. The pulley mechanism allows the braking forces to self-adjust based on the actual resistance encountered, ensuring vehicle stability while maintaining maximum braking efficiency throughout the stopping process.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If a hydraulic member is used to distribute braking force, then braking force distribution is achieved, but the system becomes imprecise due to mechanical clearances and cable position changes

Engineering Contradiction:
Improvebraking force distribution precisionVSAvoidcontrol cable connections
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent eliminates the hydraulic distribution member and its associated linkage connections. By extracting this component, the system removes the sources of mechanical clearances and cable position variations, achieving more precise and reliable braking force distribution through a simpler direct cable-pulley mechanism.

Inventive Principle:
Principle #2Taking out (Extraction)

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 design ensures balanced braking forces between the front and rear wheels, enhancing vehicle stability and reducing the risk of wheel lockup during sudden stops, while simplifying the system by avoiding complex hydraulic components.

Implementation Method 1

The transmission cable and the sheath have at least a curved portion, at which said transmission cable and said sheath rub together, such that a force is transmitted from one to the other

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3752397B1Combined front/rear braking system for a vehicle and vehicle equipped with such a braking system
Publication Date: 2021.12.15 PIAGGIO & C SPA
  • EP3752397B1 patent drawingFigure 1~2
  • EP3752397B1 patent drawingFigure 3
  • EP3752397B1 patent drawingFigure 4

AI summary

A combined front-rear braking system of a motor vehicle (100), having a hydraulically controlled front brake (107) and a mechanically controlled rear brake (109), allows effective distribution of braking forces, without the need for using complex distribution hydraulic members, and comprises; a first control member (114) of the front brake (107) and a second control member (1) of the rear brake (109), both the control members being movable between a rest position and an operative position; a hydraulic actuator (108) of the front brake (107), hydraulically controlled through said first control member; a mechanical actuator of the rear brake (109); a transmission cable (6) adapted to act under traction causing the actuation of both the front brake (107) and the rear brake (109), being connected at an end thereof to the mechanical actuator thereof, the transmission cable (6) being inserted in a sheath (7), the transmission cable (6) and the sheath (7) having at least a curved portion, at which the transmission cable (6) and the sheath (7) rub together, wherein said second control member (1) is connected to the sheath (7) so as to apply thereto a force that is transmitted to the ends of the transmission cable (6), causing the actuation of the front brake and the rear brake (107,109).