Electromechanical Brake Actuator Pressure Control
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Solution Overview
Problem
Existing brake systems for motor vehicles, particularly in 'brake-by-wire' modes, face challenges in dynamically building up brake pressure at low or medium pressure setpoints, and fail to efficiently consider large brake lining clearances, leading to suboptimal pressure build-up dynamics.
Innovation Solution
A control method and device that utilize an electromechanical actuator in a cylinder-piston arrangement, with a pressure controller and speed controller, to rapidly set and adjust pressure in the brake system, incorporating a model-based approach to enhance pressure build-up dynamics and account for varying brake lining clearances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional pressure supply device with a cylinder-piston arrangement is used, then the brake system can be actuated electrically, but the pressure build-up dynamics are insufficient at low or medium pressure setpoints
Solution Approach 1:
The control method segments the pressure build-up process into different phases: an initial phase with a first, higher actuator speed to overcome large brake lining clearances, and a subsequent phase with a second, lower actuator speed for precise pressure regulation. This segmentation allows the system to achieve fast pressure build-up dynamics while maintaining control precision, resolving the contradiction between speed and complexity.
Solution Approach 2:
The invention implements dynamic actuator speed adjustment by switching between different speed levels based on the current pressure build-up stage. The actuator speed is not fixed but adapts dynamically: high speed initially to rapidly close the brake lining clearance, then transitioning to lower speed for fine pressure control. This dynamic approach improves pressure build-up performance without requiring a fundamentally more complex device structure.
2Loss of time
If the actuator speed is increased to improve pressure build-up dynamics, then the response time is reduced, but the control precision deteriorates
Solution Approach 1:
The control method employs periodic or phased action by alternating between high-speed actuation phases and low-speed regulation phases. During the initial phase, high actuator speed is applied to rapidly reduce the brake lining clearance and build up pressure quickly. Once the desired pressure level is approached, the system transitions to a second phase with lower actuator speed to achieve precise pressure control. This periodic switching between speed levels resolves the contradiction between response time and control precision.
Solution Approach 2:
The invention implements dynamic actuator speed adjustment by switching between different speed levels based on the current pressure build-up stage. The actuator speed is not fixed but adapts dynamically: high speed initially to rapidly close the brake lining clearance, then transitioning to lower speed for fine pressure control. This dynamic approach improves pressure build-up performance without requiring a fundamentally more complex device structure.
3Speed
If a high actuator speed is used throughout the pressure build-up process, then the response time is reduced, but the energy consumption increases
Solution Approach 1:
The control method employs periodic or phased action by alternating between high-speed actuation phases and low-speed regulation phases. During the initial phase, high actuator speed is applied to rapidly reduce the brake lining clearance and build up pressure quickly. Once the desired pressure level is approached, the system transitions to a second phase with lower actuator speed to achieve precise pressure control. This periodic switching between speed levels resolves the contradiction between response time and control precision.
Solution Approach 2:
The invention implements dynamic actuator speed adjustment by switching between different speed levels based on the current pressure build-up stage. The actuator speed is not fixed but adapts dynamically: high speed initially to rapidly close the brake lining clearance, then transitioning to lower speed for fine pressure control. This dynamic approach improves pressure build-up performance without requiring a fundamentally more complex device structure.
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 faster and more precise setting of desired pressure values in the brake system, improving pressure build-up dynamics, especially for small and medium pressure requirements, and effectively managing large brake lining clearances, thus enhancing the overall control behavior and response time.
Implementation Method 1
The pressure supply device is formed by a cylinder-piston arrangement, the piston of which can be actuated by an electromechanical actuator
Implementation Method 2
A position of the pressure supply device is preferably understood to mean a variable which is characteristic of a position or location or setting of the electromechanical actuator or of the piston of the pressure supply device
Data Source
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AI summary
The invention relates to a method for controlling a braking system for motor vehicles comprising a hydraulically actuatable wheel brake which can be actuated by an electronically controllable pressure supply device that comprises a cylinder-piston arrangement with a hydraulic pressure chamber, the piston of which can be displaced by an electromechanical actuator such that a pre-defined desired pressure value can be adjusted in the hydraulic pressure chamber, a position of the pressure supply device being detected, and an actual pressure (Pv, Ist) of the pressure supply device being determined by means of a measurement device. In order to allow braking pressure to build dynamically at low or medium desired pressure values, manipulated variables (ωAkt, soll, MAkt, soll) are formed for the electromechanical actuator (1) on the basis of the pre-defined desired pressure value (Pv, soll) and of an actual pressure value (Pv, Dach), the actual pressure value (Pv, Dach) being determined on the basis of the desired pressure value (Pv, soll) by weighted addition of the actual pressure (Pv, Ist) and of a model pressure (Pv, Mod) calculated from a current position (XAkt) of the pressure supply device.