Master Cylinder Stroke Velocity Ratio Control
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Solution Overview
Problem
Existing master cylinder apparatuses in hydraulic brake systems face challenges in improving the operability of brake operating members, particularly in reducing initial response delay and modifying stroke velocity ratios effectively.
Innovation Solution
The apparatus includes an input piston and a pressure piston with a stroke velocity ratio modification device that adjusts the ratio in at least two stages by controlling communication conditions between the inter-piston chamber, opposing chamber, and reservoir, using a stepped shape for the pressure piston and solenoid valves to manage fluid pressure and piston movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the stroke velocity ratio is increased in the initial stage of brake operation, then the initial response delay is suppressed, but the stroke velocity ratio becomes too large causing poor operability
Solution Approach 1:
The stroke velocity ratio modification device dynamically adjusts the stroke velocity ratio in at least two stages during brake operation. In the initial stage, the ratio is increased to reduce response delay, and in the normal use region, the ratio is reduced to improve operability. This dynamic adjustment resolves the contradiction between initial response and overall operability.
Solution Approach 2:
The patent changes the stroke velocity ratio parameter during different phases of brake operation. By modifying this parameter from a high value in the initial stage to a lower value in the normal use region, the system achieves both fast initial response and good operability, resolving the technical contradiction.
2Ease of operation
If the stroke velocity ratio is kept small in normal use region, then the operability is improved, but the initial response delay increases
Solution Approach 1:
The system dynamically switches between different stroke velocity ratio settings based on the brake operation phase. The stroke velocity ratio modification device enables the ratio to be small during normal use for good operability, and large during initial stage for fast response, thus resolving the contradiction.
Solution Approach 2:
The brake operation is divided into periodic stages: initial stage and normal use region. The stroke velocity ratio modification device applies different ratio settings in each stage, with the ratio being increased in the initial stage and reduced in the normal use region, resolving the time-loss versus operability contradiction.
3Reliability
If the pressure piston is caused to advance by fluid pressure in back surface chamber, then the input piston advancement is restricted, but the stroke velocity ratio control becomes complex
Solution Approach 1:
The communication condition control device acts as an intermediary mechanism that controls the communication conditions between the inter-piston chamber, opposing chamber, and reservoir. By managing fluid pressure distribution through this intermediary device, the system achieves stroke velocity ratio modification without overly complex direct control of piston advancement.
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 enhances the operability of brake operating members by reducing the initial response delay and modifying the stroke velocity ratio, improving the operating feeling for drivers and maintaining system stability even during electrical system abnormalities.
Implementation Method 1
fluid pressure from a rearward back surface chamber
Implementation Method 2
a master cylinder apparatus that has a master cylinder and is included in a hydraulic brake system
Implementation Method 3
an effective pressure receiving surface area a1 of a part of the pressure piston that receives fluid pressure from the opposing chamber is smaller than an effective pressure receiving surface area a2 of a part of the pressure piston that receives fluid pressure from the inter-piston chamber
Data Source
AI summary
A master cylinder apparatus includes: an input piston that can be moved forward by operating a brake operating member; a pressure piston provided in front of the input piston to be capable of moving relative to the input piston; and a stroke velocity ratio modification device capable of modifying a stroke velocity ratio, which is a ratio between a stroke velocity of the pressure piston and a stroke velocity of the input piston, in at least two stages within a range not greater than a predetermined value larger than 1.