Electromechanical Brake Booster Position Control
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Solution Overview
Problem
The control quality of electromechanical brake boosters is compromised due to fluctuations in brake pressure at vehicle wheels, which are influenced by various parameters such as disc runout, temperature, and actuation speed, leading to excessive pressure differences and unsatisfactory support force delivery.
Innovation Solution
Implementing a device with an electrical actuating device, such as a servomotor, that uses motor position control instead of conventional pressure control, combined with sensors to determine the absolute operating position, allowing for precise determination of the braking state variable and application of assisting force, thereby improving control quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure control is used for electromechanical brake booster regulation, then the brake pressure can be monitored, but the control quality deteriorates due to pressure fluctuations caused by disc runout, temperature, and actuation speed
Solution Approach 1:
The patent replaces pressure-based control (hydraulic/mechanical measurement) with motor position control (electrical measurement). The control unit determines the actual braking state variable from the motor position and characteristic curve instead of relying on pressure sensor readings, thereby eliminating the harmful effects of pressure fluctuations while maintaining measurement capability
Solution Approach 2:
The patent introduces a characteristic curve as an intermediary relationship between motor position and braking state variable. This characteristic curve, which can be pre-determined through calibration, allows the system to translate motor position measurements into accurate braking state information without being affected by pressure fluctuations
2Device complexity
If ESP admission pressure is used as actual value for controlling electromechanical brake booster, then the control system is simplified, but excessive pressure differences occur between measured and actual pressure at vehicle wheels
Solution Approach 1:
The patent replaces hydraulic pressure measurement (ESP admission pressure) with electrical motor position measurement. The motor position provides a direct, fluctuation-free measurement of the actuator state, which is then correlated to the braking state variable through a characteristic curve, eliminating the indirect and fluctuating pressure measurement approach
Solution Approach 2:
The patent establishes a feedback loop where the control unit continuously monitors motor position, determines the actual braking state variable from the characteristic curve, and uses this information to regulate the electromechanical brake booster. This feedback mechanism provides accurate, real-time control without the delays and inaccuracies of pressure-based feedback
3Reliability
If motor position control is implemented instead of pressure control, then control quality is improved, but additional sensors and computing means are required
Solution Approach 1:
The patent makes the control unit multi-functional by having it perform both motor position measurement and braking state variable determination. The control unit serves as the sensor, signal processor, and regulator, eliminating the need for separate dedicated components and reducing overall system complexity despite the enhanced control functionality
Solution Approach 2:
The electromechanical brake booster system serves itself by using its own motor position information to determine the braking state variable. The motor that actuates the brake mechanism also provides the measurement signal, eliminating the need for separate sensing systems and reducing component complexity
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 enhances the control quality of electromechanical brake boosters by accurately determining the braking state and applying the necessary assisting force, leading to improved braking performance and stability.
Implementation Method 1
an electric motor with a stator and a rotor, which are arranged concentrically around the piston rod
Data Source
Figure 1
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AI summary
The invention relates to a device and method for electromechanical brake servo assistance on vehicles, comprising an operating means (2) which a driver may affect, operationally connected to at least one brake cylinder (3), and an electrical actuator (1), provided for operation of the at least one brake cylinder in at least one direction, whereby a servo assistance force is determined by at least one computer means (23), the servo force is applied by means of the electrical actuator, a first sensor (20) is provided for generation of a quantitative signal relating to the relative operating position of the electrical actuator, a second sensor (18) is provided for generation of a qualitative signal for the approximate operational position of the electrical actuator and the instantaneous absolute operational position of the electrical actuator may be determined by the computing means from the quantitative and the quantitative signals and hence the brake status parameter (F1) may be derived, corresponding to an actual condition of a braking process.