Hydraulic Master Cylinder Piston Biasing for Brake Assembly

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Solution Overview

Problem

Existing hydraulic master cylinders require adjustment to eliminate clearance between the piston and the push member during assembly, leading to inefficiencies in brake system assembly and operation.

Innovation Solution

Incorporating a bias member, such as a compression spring, to maintain contact between the push member and the piston, eliminating the need for clearance adjustments by ensuring constant contact and stable operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the input piston is positioned relative to the control piston and body but not positioned relative to the input rod, then the assembly structure is simplified, but a clearance is generated between the input piston and input rod requiring adjustment work

Engineering Contradiction:
Improveassembly structureVSAvoidadjustment work
Core Design Contradiction:
Device complexityVSEase of manufacture

Solution Approach 1:

A positioning structure is provided between the input piston and input rod in advance, which preliminarily determines their relative positions. This preliminary positioning eliminates the clearance between the input piston and input rod before assembly is completed, thereby avoiding the need for adjustment work while maintaining the simplified assembly structure.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If adjustment work is performed to decrease clearance between input piston and input rod, then brake operation precision is improved, but assembly time and productivity are reduced

Engineering Contradiction:
Improveclearance controlVSAvoidassembly time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The positioning structure is designed to preliminarily establish the correct relative position between the input piston and input rod during assembly. This preliminary action ensures that the clearance is automatically controlled to the required precision without requiring subsequent adjustment operations, thereby maintaining manufacturing precision while significantly reducing assembly time and improving productivity.

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 design enhances the assembly process by eliminating the need for clearance adjustments, improving workability and maintaining consistent hydraulic pressure, thus ensuring reliable brake operation without the need for additional adjustments.

Implementation Method 1

a first bias member, which biases the push member toward the piston to bring the push member into contact with the piston in the case where the piston is not moved at least nearly toward the first oil chamber

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP1961636B1Hydraulic master cylinder and vehicle provided with the same
Publication Date: 2013.04.24 YAMAHA MOTOR CO LTD
  • EP1961636B1 patent drawingFigure 1
  • EP1961636B1 patent drawingFigure 2
  • EP1961636B1 patent drawingFigure 3

AI summary

A hydraulic master cylinder (30), for example for a rear brake of a vehicle, comprises a master cylinder (31) including a first oil chamber (31a) and a second oil chamber (31b), a piston (32) including a piston oil passage portion (32a) connected to the first oil chamber (31) a and the second oil chamber (31b) of the master cylinder (31), a push member (42), which abuts against the piston (32) to move the piston (32) to thereby generate a hydraulic pressure in the first oil chamber (31a), and a compression spring (43), which biases the push member (42) toward the piston (32) (in an arrow A direction) in the case where the piston (32) is not moved at least nearly toward the first oil chamber (31a), thereby bringing the push member (42) into contact with the piston (32).