Electronic Hydraulic Brake Master Cylinder Segmentation
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Solution Overview
Problem
The existing electronic hydraulic brake (EHB) system takes a long time to form braking pressure in abnormal operation modes, which delays the braking process due to the slow separation of the input shaft from the master cylinder piston when the brake pedal is pressed.
Innovation Solution
The system includes a pedal simulator with a simulator piston and springs, a control piston, and a hydraulic pressure supply, allowing for complete separation of the input shaft from the master cylinder in normal operation and quick formation of high braking pressure with reduced pedal force in abnormal operation by utilizing a larger control piston diameter and a locking mechanism to restrict movement, enabling efficient pressure amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake pedal is pressed in abnormal operation mode, then the brake fluid flows into the wheel cylinder through the master cylinder, but it takes a long time to block the fluid and form braking pressure
Solution Approach 1:
The master cylinder is divided into two separate chambers: a first chamber (140) for normal braking operations and a second chamber (141) for abnormal operations. This segmentation allows independent control of fluid flow paths, enabling rapid blocking of the second chamber's fluid flow to the wheel cylinder through a blocking valve when abnormal operations are detected, thus quickly forming braking pressure without delay.
Solution Approach 2:
A blocking valve (165) is introduced as an intermediary component between the second chamber (141) and the wheel cylinder. This valve rapidly blocks the fluid flow path from the second chamber to the wheel cylinder when abnormal operations are detected, preventing delayed pressure formation and ensuring quick braking response.
2Force
If a conventional master cylinder is used in abnormal operation mode, then the piston moves forward to deliver pressure, but the braking pressure formation is delayed
Solution Approach 1:
The master cylinder is segmented into two chambers with separate pistons: a first piston (110) for normal operations and a second piston (130) for abnormal operations. The second chamber (141) is designed to rapidly deliver high braking pressure to the wheel cylinder through a dedicated fluid passage, bypassing the slower mechanical piston movement of conventional designs and achieving quick pressure formation.
Solution Approach 2:
The system utilizes hydraulic pressure delivery through dedicated fluid passages in the second chamber (141) for abnormal operations. High-pressure brake fluid is rapidly delivered to the wheel cylinder through this hydraulic path, achieving quick braking pressure formation without relying solely on mechanical piston movement.
3Ease of operation
If the pedal simulator is coupled to the input shaft, then pedal repulsive force is supplied, but complete separation in abnormal mode is difficult to achieve
Solution Approach 1:
The pedal simulator (250) is segmented into a normal operation mode where it is coupled to the input shaft (310) to supply pedal repulsive force, and an abnormal operation mode where it is completely separated from the input shaft. This segmentation is achieved through a push rod (400) that can disengage, allowing the pedal simulator to be isolated from the braking system during abnormal operations, ensuring complete separation and preventing interference with rapid pressure formation.
Solution Approach 2:
The connection between the pedal simulator and the input shaft is made dynamic rather than fixed. The push rod (400) allows the pedal simulator to be coupled during normal operations for repulsive force feedback, and automatically separated during abnormal operations when rapid pressure formation is critical, adapting the connection state based on operational conditions.
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 allows for rapid generation of high braking pressure with less pedal force in abnormal operation modes, ensuring quicker braking response and enhanced safety by effectively separating the input shaft from the master cylinder piston, thus overcoming the delay in pressure formation.
Implementation Method 1
a first spring (170) supporting the first piston (110) through an opening (101)
Implementation Method 2
a second spring (171) supporting the second piston (130) between the second piston (130) and a bottom wall (104) of the master cylinder (100)
Implementation Method 3
a simulation piston (41) and a simulation spring (42) elastically supporting the simulation piston (41)
Implementation Method 4
the brake fluid of the second chamber (31) flows into the wheel cylinder when the driver steps on the brake pedal
Data Source
AI summary
A vehicle brake device includes an input shaft coupled to a brake pedal, a pedal operation detector, a pedal simulator coupled to the input shaft in a control housing, a master cylinder, a control piston, a control chamber, and a hydraulic pressure supply, wherein the pedal simulator includes a pedal simulator piston, a pressing member, a simulator piston provided in the pedal simulator piston, and a push rod which is accommodated in the pressing member while being spaced apart from a bottom wall of a guide groove by passing through the pedal simulator piston and the simulator piston from the control piston to the input shaft, and wherein a diameter of the master cylinder is greater than a diameter of the simulator piston, and a diameter of the control piston is greater than a diameter of the master cylinder.