Hydraulic Master Cylinder Fluid Routing for Regenerative Braking
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Solution Overview
Problem
Existing braking systems in hybrid vehicles often require a deadband displacement range to differentiate between regenerative and hydraulic braking, which may not be desirable in all vehicles, and there is a need to inhibit hydraulic braking during initial brake pedal movement to prioritize regenerative braking.
Innovation Solution
A braking system with a master cylinder and dual fluid circuits, where initial brake pedal displacement transfers fluid to a reservoir to inhibit hydraulic braking, and further displacement activates hydraulic braking, using a valve to control fluid flow and eliminate the need for a deadband gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a deadband displacement range is used to differentiate between regenerative and hydraulic braking, then regenerative braking can be activated during initial pedal movement, but a gap or deadband must be introduced into the mechanical connection which complicates the system design and may not be desirable in all vehicles
Solution Approach 1:
The patent replaces the mechanical deadband gap with a fluid-based control mechanism. Instead of using a physical gap in the connecting rod connection to differentiate braking modes, the system uses a master cylinder with a displacement threshold mechanism that directs brake fluid to either the reservoir or wheel brakes based on piston travel distance, eliminating the need for mechanical complexity while achieving the same functional differentiation
Solution Approach 2:
The master cylinder acts as an intermediary device that mediates between the brake pedal input and the two braking systems. The piston displacement within the master cylinder serves as the intermediary mechanism that automatically routes brake fluid flow based on the magnitude of pedal input, replacing the need for complex mechanical switching arrangements
2Loss of energy
If brake pedal movement within a deadband range activates only regenerative braking, then energy recovery is prioritized, but the system requires a disconnection mechanism between connecting rods which increases device complexity
Solution Approach 1:
The patent substitutes the mechanical disconnection mechanism with a hydraulic routing system. The master cylinder uses piston displacement to control valve positioning, which automatically directs brake fluid either to the reservoir (during initial pedal movement for regenerative braking) or to the wheel brakes (when pedal displacement exceeds the threshold), achieving energy recovery prioritization without mechanical complexity
Solution Approach 2:
The master cylinder system is self-regulating based on piston displacement. As the piston moves further during brake pedal input, it automatically transitions the fluid routing from the reservoir path to the wheel brakes path without requiring external control signals or complex switching mechanisms, allowing the system to serve itself in differentiating between light and heavy braking 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 solution allows for seamless transition between regenerative and hydraulic braking without a deadband gap, ensuring efficient energy management and improved braking control by prioritizing regenerative braking during initial pedal movement.
Implementation Method 1
A piston is disposed within the master cylinder and translatable from the proximal end toward the distal end in response to brake pedal displacement. Initial brake pedal displacement translates the piston between the proximal end and the first outlet and transfers brake fluid from the master cylinder to the fluid reservoir
Implementation Method 2
A valve is disposed in the first fluid circuit. The valve is biased closed to block fluid from returning to the brake fluid reservoir via the first fluid circuit such that fluid is rather expelled into the second fluid circuit and toward the wheel brakes
Implementation Method 3
A second fluid circuit connects the second outlet of the master cylinder toward wheel brakes and supplies hydraulic fluid from the master cylinder to the wheel brakes in response to the piston being translated a length greater than a distance between the proximal end and the first outlet
Data Source
AI summary
A braking system in a hybrid vehicle is provided. The braking system includes a master cylinder having a first outlet, a second outlet, and a piston disposed therein and translatable from a proximal end to a distal end in response to brake pedal displacement. A brake fluid reservoir supplies hydraulic fluid to the master cylinder. A first fluid circuit connects the first outlet of the master cylinder to the brake fluid reservoir. A second fluid circuit connects the second outlet of the master cylinder to wheel brakes and supplies hydraulic fluid from the master cylinder to the wheel brakes in response to brake pedal displacement. The first outlet of the master cylinder is disposed between the second outlet and the proximal end of the master cylinder such that initial brake pedal displacement transfers brake fluid from the master cylinder to the fluid reservoir to inhibit hydraulic braking during regenerative braking.