Brake Piston Pre-positioning for Fast Electromechanical Braking
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Solution Overview
Problem
Existing vehicle braking systems face inefficiencies in transitioning between hydraulic and electromechanical braking modes, leading to prolonged time in building up electromechanical braking force and potential unintended contact with the brake disk.
Innovation Solution
A method that determines the position of the brake piston's braking start point between the starting position and the brake contact point, allowing for reduced free travel and quicker transition to electromechanical braking force generation, utilizing electric motor state variables like motor current or speed, and accounting for hydraulic bias pressure and tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake piston is positioned at the starting position with no braking torque, then the brake lining and brake disk are sufficiently separated to exclude unintended contact, but the time required to build up electromechanical braking force is prolonged
Solution Approach 1:
The brake piston is pre-positioned at a braking start point that is closer to the brake contact point than the traditional starting position. This preliminary positioning reduces the remaining free travel distance, allowing the brake piston to reach the brake contact point faster when electromechanical braking force is demanded, thereby reducing the time to build up braking force while still maintaining sufficient distance to prevent unintended contact during normal operation
Solution Approach 2:
The system dynamically adjusts the brake piston position based on operational state. The brake piston can be positioned at different locations: at the braking start point during normal operation to minimize response time, and can be moved to the brake contact point when electromechanical braking force is demanded. This dynamic positioning strategy optimizes both reliability and response time
2Productivity
If the brake piston is moved closer to the brake contact point, then the time to build up braking force is reduced, but the risk of unintended contact and brake drag increases
Solution Approach 1:
The brake piston is pre-positioned at an optimized braking start point that balances two competing requirements: being close enough to the brake contact point to minimize response time, yet far enough to maintain a safety margin that prevents unintended contact. This preliminary positioning at an intermediate point optimizes both productivity and reliability
3Reliability
If the brake piston remains at the starting position for extended periods, then reliability is maintained, but the system response time to braking demand is increased
Solution Approach 1:
Instead of keeping the brake piston at the traditional starting position for extended periods, the system performs preliminary positioning at the braking start point closer to the brake contact point. This preliminary action maintains system stability while significantly reducing the response time when braking force is demanded, as the brake piston has less distance to travel
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 method reduces the time required to build up electromechanical braking force and ensures reliable, efficient braking by minimizing free travel and preventing unintended contact, enhancing braking system reliability and performance.
Implementation Method 1
the rotational movement of the rotor of the electric brake motor is advantageously transferred into an axial actuation movement of a spindle nut
Implementation Method 2
The hydraulic fluid of the hydraulic vehicle brake also acts on the brake piston in order to produce a braking force during normal brake operation
Data Source
AI summary
A method for providing a brake force in a vehicle with a hydraulic vehicle brake and an electromechanical brake device includes determining a position of a brake piston at a brake contact point on the basis of a state variable of an electric brake motor when the electromechanical brake device is released. The method further includes displacing the brake piston in a positioning operation until reaching a braking start point.