Vehicle Brake Hydraulic Circuit Separation for Pulsation Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing brake control devices for vehicles face issues with fluidic separation during normal braking and are susceptible to hydraulic pressure pulsations, leading to resonance and excessive brake fluid leakage, especially in brake-by-wire configurations and when dealing with regenerative cooperation control.
Innovation Solution
A brake control device that includes an electric pump, pressure adjustment valves, a master unit with a servo and master chamber, and a simulator, which are fluidically separated to maintain operation characteristics and prevent brake fluid flow between systems, ensuring reliable operation and reduced pulsation influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If pumps are used to supply pressure to the back pressure chamber, then the pressure can be adjusted, but hydraulic pressure pulsations cause resonance and affect operation characteristics
Solution Approach 1:
The brake system is divided into two independent hydraulic circuits: a first hydraulic circuit connecting the master cylinder to front wheel cylinders, and a second hydraulic circuit connecting the master cylinder to rear wheel cylinders. This segmentation isolates the rear wheel cylinder system from pump pulsations, preventing resonance and maintaining stable operation characteristics while still allowing pressure adjustment in the back pressure chamber.
2Quantity of substance
If the proportional electromagnetic valve is set to OFF position, then brake fluid is not returned to the reservoir tank, but brake hydraulic pressure cannot be reduced
Solution Approach 1:
A third hydraulic circuit is introduced as an intermediary pathway, connecting the back pressure chamber to the reservoir tank through a third electromagnetic valve. This allows brake fluid to be returned to the reservoir tank independently of the proportional electromagnetic valve position, enabling brake hydraulic pressure reduction while maintaining brake fluid retention in the system.
3Productivity
If fluid passages of two systems communicate with each other, then pressure increase is assisted, but large amounts of brake fluid may flow out if a wheel cylinder is broken
Solution Approach 1:
The hydraulic system is segmented into independent first and second hydraulic circuits that do not communicate with each other during normal braking. The master cylinder connects to the front wheel cylinders through the first circuit and to the rear wheel cylinders through the second circuit. This segmentation prevents brake fluid leakage between systems while still allowing assisted pressure increase through the third circuit when needed.
4Device complexity
If a stroke simulator is omitted, then device complexity is reduced, but operation force generation is affected by pump pulsations
Solution Approach 1:
The hydraulic system is segmented into independent first and second hydraulic circuits, with the third circuit providing a dedicated pathway for operation force generation. By isolating the operation force generation pathway from the pump supply pathway, the system achieves stable operation force characteristics without requiring a complex stroke simulator, maintaining reliability while controlling device complexity.
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
The solution effectively separates fluidic systems during normal braking, reduces the impact of hydraulic pressure pulsations, and ensures stable operation characteristics, enhancing the reliability and efficiency of the brake control device, particularly in regenerative cooperation control scenarios.
Implementation Method 1
an electric pump (DC) connected to a reservoir (RV) of the vehicle, a pressure adjustment valve (UA) that adjusts a hydraulic pressure of a brake fluid (BF) discharged by the electric pump (DC)
Implementation Method 2
a pressure adjustment valve (UA) that adjusts a hydraulic pressure of a brake fluid (BF) discharged by the electric pump (DC) to an adjustment hydraulic pressure (Pa)
Implementation Method 3
the servo chamber (Rs) into which the brake fluid at the adjustment hydraulic pressure (Pa) is supplied and in which the adjustment hydraulic pressure (Pa) is converted to a forward force (Fa) of a master piston (PM)
Implementation Method 4
the master chamber (Rm) that is fluidically separated from the servo chamber (Rs) by the master piston (PM), that is connected to the front wheel cylinder (CWf), in which a rearward force (Fb) that is converted from the hydraulic pressure (Pwf) of the front wheel cylinder (CWf)
Data Source
AI summary
A brake control device includes an electric pump, a pressure adjustment valve that adjusts a hydraulic pressure of a brake fluid discharged by the electric pump to an adjustment hydraulic pressure and supplies the brake fluid in a rear wheel cylinder, and a master unit provided with a servo chamber into which brake fluid at the adjustment hydraulic pressure is supplied and in which the adjustment hydraulic pressure is converted into a forward force of a master piston, and a master chamber fluidically separated from the servo chamber by the master piston and connected to the front wheel cylinder and in which a rearward force converted from the hydraulic pressure in the front wheel cylinder and is applied to the master piston. Also included is an input unit provided with an input chamber and a simulator, and a controller configured to control the electric pump and the pressure adjustment valve.