Brake Isolation Valve Control for Pressure-Decoupled Wheel Brakes
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Solution Overview
Problem
Brake systems for vehicles face challenges in efficiently managing brake pressure and reducing the load on pressure generation devices, particularly during dynamic braking conditions and hydraulic fluid replenishment, where precise pressure control and decoupling are critical.
Innovation Solution
A method and system that utilize an isolation valve preloaded to prevent backflow, allowing hydraulic decoupling of the wheel brake from the pressure generation device, reducing the load on the pressure generation device by lowering the system pressure and automatically recoupling when the pressure increase starts, ensuring reliable and efficient brake operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure generation device continuously maintains brake pressure, then the brake system remains ready for immediate braking, but the load on the pressure generation device increases and energy consumption rises
Solution Approach 1:
The hydraulic system is divided into two separate circuits: an actuating circuit that generates brake requests and an active circuit that applies brake pressure. The isolation valve physically separates these circuits, allowing the pressure generation device in the active circuit to be deactivated while maintaining brake pressure through the sealed hydraulic path, thus reducing energy consumption while preserving brake readiness.
Solution Approach 2:
The brake pressure is generated in advance and stored in the sealed active circuit before braking is actually needed. The isolation valve maintains this pre-generated pressure without requiring continuous power input, enabling the system to be ready for immediate braking without sustained energy input to the pressure generation device.
2Ease of operation
If the isolation valve is opened to allow hydraulic coupling, then pressure can be transmitted to the wheel brake, but pressure peaks occur during coupling
Solution Approach 1:
The pressure generation device is actuated in advance to generate the required brake pressure before the isolation valve is opened. When the valve opens, the pressure is already present in the actuating circuit, allowing smooth transmission without sudden pressure peaks. This preliminary pressure generation avoids shock loads during coupling.
3Use of energy by moving object
If the pressure generation device is deactivated to reduce load, then energy consumption decreases, but pressure control becomes dependent on the sealed hydraulic path
Solution Approach 1:
The active circuit with the pressure generation device is extracted and separated from the actuating circuit using the isolation valve. This allows the pressure generation device to be completely deactivated and removed from the pressure maintenance function, which is then handled by the sealed hydraulic path in the active circuit, reducing energy consumption while maintaining pressure control capability.
4Reliability
If the isolation valve is preloaded to closed state, then backflow prevention is reliable, but the valve requires higher opening force
Solution Approach 1:
The pressure generation device is actuated in advance to generate sufficient pressure in the actuating circuit before the isolation valve needs to open. This preliminary pressure buildup ensures that when the valve does open, the existing pressure differential provides the force needed to overcome the preload, minimizing the additional opening force required while maintaining reliable backflow prevention.
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 enables reliable and efficient brake operation by maintaining set brake pressure independently of the pressure generation device, reducing the load on the device and avoiding pressure peaks, while ensuring seamless hydraulic coupling and decoupling, even under rapidly changing braking conditions.
Implementation Method 1
The isolation valve is preloaded to the closed state by a preloading device, e.g., by a spring. The force applied to the valve, in particular the valve body, by the preloading device thus acts in the return-flow direction or counter to an inflow direction of the hydraulic fluid from the pressure-generator-side section into the brake-side section of the hydraulic path.
Implementation Method 2
a master brake cylinder actuated by a manual actuation device generates a hydraulic pressure in a brake circuit in order to actuate wheel brakes
Implementation Method 3
The isolation valve is situated in the hydraulic path in such a way that a valve body is pressed against a valve seat by a pressure that prevails in the brake-side section of the hydraulic path and is greater than the pressure in a pressure-generator-side section of the hydraulic path between the isolation valve and the pressure generator.
Data Source
AI summary
A method for operating a brake system. A brake request signal is generated, and a setpoint brake pressure required in an active circuit is ascertained. An actual brake pressure is set according to the setpoint brake pressure. A wheel brake actuated by the active circuit is hydraulically decoupled from the pressure generation device by closing an isolation valve, which is situated between the pressure generation device and the wheel brake, the isolation valve is preloaded to a closed state counter to an inflow direction of a volume flow into a brake-side section between the isolation valve and the wheel brake. A hydraulic recoupling of the wheel brake takes place by opening the isolation valve in that the actual brake pressure is set according to the setpoint brake pressure and an opening force is simultaneously applied to the isolation valve such that a compensation of a closing force takes place.