Integrated Parking Brake Pressure Modeling After Release
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Solution Overview
Problem
The hydraulic dependency between the parking brake and the electrohydraulic brake system causes incorrect pressure modeling, leading to overbraking, noise, and vibration issues due to the displacement of brake fluid volume by the integrated parking brake, which is not accounted for in existing systems.
Innovation Solution
A method that considers the displaced brake fluid volume by the integrated parking brake, adjusting the brake system operation to compensate for this excess volume by advancing the pressure piston's standby position and incorporating it into the pressure model, thereby avoiding unnecessary fluid drainage and correcting pressure imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the integrated parking brake is released, then the brake linings are released and the parking brake function is completed, but additional brake volume is moved into the wheel causing overbraking and potential locking
Solution Approach 1:
The pressure model is updated in advance to account for the volume displacement that will occur when the parking brake is released. The controller anticipates the volume change and adjusts the pressure control accordingly, preventing overbraking before it occurs by pre-correcting the pressure model parameters
Solution Approach 2:
The system continuously monitors the state of the parking brake and the resulting volume displacement, feeding this information back to the pressure model. The controller adjusts the pressure control based on the detected volume change, creating a closed-loop system that maintains accurate pressure control despite the parking brake's volume displacement
2Device complexity
If the pressure model does not account for the integrated parking brake, then the pressure control is simplified, but incorrect pressure values are calculated leading to overbraking
Solution Approach 1:
The pressure model parameters are dynamically adjusted based on the parking brake state. When the parking brake is activated or released, the volume displacement parameter is modified in the pressure model, allowing the same basic model structure to accurately reflect different operational conditions without requiring a completely different model
3Reliability
If the outlet valves are opened to dissipate residual pressure, then the pressure balance is corrected, but noise and vibration occur irritating the driver
Solution Approach 1:
Instead of allowing residual pressure to build up and then dissipating it (which causes noise), the system takes preliminary action by adjusting the pressure model to account for the incoming volume. This prevents the pressure imbalance from occurring in the first place, eliminating the need for noisy pressure dissipation
Solution Approach 2:
The volume displacement that would normally be harmful (causing overbraking and noise) is converted into useful information. The controller uses the knowledge of the impending volume change to proactively adjust pressure control, transforming a potential problem into a controlled parameter
4Adaptability or versatility
If the isolation valves are closed to isolate the pressure supply device, then the system operates independently, but the displaced volume cannot be depleted causing pressure imbalances
Solution Approach 1:
The pressure model acts as an intermediary that mediates between the isolated pressure supply device and the wheel brakes. Even when isolation valves are closed, the pressure model accounts for the volume displacement caused by the parking brake, allowing the isolated system to maintain accurate pressure control through computational compensation rather than physical fluid communication
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 approach prevents overbraking, reduces noise and vibration, and maintains accurate pressure control by accounting for the displaced volume, ensuring smooth operation and compliance with driver demands.
Implementation Method 1
brake pressure is actively built up in the wheel brakes by means of the pressure supply device
Implementation Method 2
The brake fluid volume is enclosed in the corresponding wheel brakes until the parking brake is released
Implementation Method 3
the brake fluid volume in at least two wheel brakes by conveying brake fluid, and thereby increases the wheel brake pressure
Implementation Method 4
A depletion of residual pressure via normally closed outlet valves of the wheel brakes
Data Source
AI summary
A method for operating a brake system, which comprises hydraulically actuatable wheel brakes with brake linings; a brake fluid reservoir; a master brake cylinder; a pressure supply device with a pressure piston that can be moved into a pressure chamber; an integrated parking brake, wherein, in a normal operating mode, brake pressure is actively built up in the wheel brakes by means of the pressure supply device, and wherein, in a parking operating mode, the integrated applies the brake linings of at least two wheel brakes, and wherein, when the integrated parking brake is released, the application of the linings is withdrawn again, wherein after the integrated parking brake has been released, the brake fluid volume displaced by the integrated parking brake is taken into consideration for the subsequent operation in the normal operating mode.