Brake System Circuit Isolation Valve for Leakage Protection
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Solution Overview
Problem
Existing brake systems for motor vehicles lack a compact and cost-effective solution for 'brake-by-wire' and fallback operating modes, particularly in scenarios involving leakage, which compromises availability and operational reliability.
Innovation Solution
A brake system with a single-circuit master brake cylinder and a normally open circuit isolation valve, allowing for a single-circuit configuration in de-energized states that can switch to a two-circuit configuration using an electrically actuatable circuit isolation valve, enabling pressure separation into two hydraulic brake circuits without disabling the pressure-providing device, and incorporating a sequence valve for hydraulic isolation in case of leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-circuit master brake cylinder is used with a normally open circuit isolation valve, then the brake system achieves compact design and cost-effectiveness, but the system lacks inherent separation into two brake circuits for leakage protection
Solution Approach 1:
The circuit isolation valve transitions from a static fixed-state component to a dynamic switchable component. The valve can change its state between normally open (single-circuit mode) and normally closed (two-circuit mode), allowing the brake system to adapt its configuration dynamically based on operational requirements and leakage conditions, thus resolving the contradiction between structural simplicity and reliability
Solution Approach 2:
The system changes the flow resistance parameter of the circuit isolation valve from open to closed state. By controlling the valve's opening degree (fully open for single-circuit, fully closed for two-circuit), the system transforms a single-circuit master brake cylinder into an equivalent two-circuit configuration when needed, achieving both compact design and leakage protection
2Reliability
If a tandem master brake cylinder with floating piston is used to separate brake circuits, then the system provides inherent two-circuit separation for reliability, but the installation length and device complexity increase
Solution Approach 1:
The brake supply line is segmented into two separate line sections (first line section and second line section) by the circuit isolation valve. This segmentation allows the single-circuit master brake cylinder to function as two independent brake circuits when the valve is closed, achieving circuit separation without requiring a longer tandem master brake cylinder
Solution Approach 2:
The circuit isolation valve acts as an intermediary component between the single-circuit master brake cylinder and the brake supply line. By introducing this valve, the system achieves two-circuit separation functionality without replacing the compact single-circuit master brake cylinder, thus maintaining short installation length while providing reliability
3Reliability
If a normally closed circuit isolation valve is used to separate brake circuits, then two-circuit mode is achieved, but the system cannot operate in single-circuit mode and requires additional components for flexibility
Solution Approach 1:
Instead of using a normally closed valve that requires active opening to achieve single-circuit mode, the invention inverts the approach by using a normally open valve that requires active closing to achieve two-circuit mode. This inversion simplifies the default state to single-circuit operation and makes the two-circuit mode an activated feature, enhancing system versatility without additional components
Data Source
AI summary
A motor vehicle brake system having at least four hydraulically actuatable wheel brakes, including an electrically actuatable inlet valve for each wheel brake. A master brake cylinder actuable by a brake pedal is separably hydraulically connected via an isolation valve to a brake supply line to which the inlet valves are connected, and an electrically controllable pressure-providing device having a pressure space hydraulically connected to the brake supply line. An electrically actuatable circuit isolation valve inline with the brake supply line. With the circuit isolation valve closed the brake supply line is hydraulically separated into first and second line sections. The first line section connected to two of the inlet valves, and the second line section connected to the remaining inlet valves. The pressure space is hydraulically connected to the second line section. The circuit isolation valve is normally open, wherein the pressure chamber of the master brake cylinder is connected to the first line section via the isolation valve.