Electrohydraulic Brake Feedback Current Management
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Solution Overview
Problem
Electrohydraulic vehicle brake systems with electromechanical actuators face challenges in managing feedback currents during multiplex operation, leading to voltage peaks that can harm other electrical consumers and require limiting the maximum permitted feedback current, which can restrict the system's ability to rapidly adjust hydraulic pressure at wheel brakes.
Innovation Solution
The system generates feedback current by operating the electric motor as a generator and selectively supplies this current to electrical consumers, such as valves or resistors, during peak feedback current periods, reducing thermal load and preventing voltage spikes by using pulse width modulation or connecting consumers only when the feedback current exceeds a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback current is limited to protect electrical components, then system safety is improved, but the ability to rapidly adjust hydraulic pressure is restricted
Solution Approach 1:
The patent converts the harmful feedback current into a beneficial resource by using it to power electrical consumers such as heating elements, seat heaters, or other auxiliary systems. This approach eliminates the harmful effect of voltage peaks while simultaneously providing useful functionality, thereby protecting the electrical system without compromising the electromechanical actuator's performance in pressure modulation.
2Adaptability or versatility
If multiple valves are operated simultaneously in multiplex mode, then wheel-specific pressure modulation is achieved, but voltage peaks and feedback current issues occur
Solution Approach 1:
The patent addresses the voltage peak problem by redirecting the feedback current generated during multiplex valve operation into useful electrical consumers. This allows the system to maintain simultaneous multi-valve operation for independent wheel control while converting the harmful voltage fluctuations into beneficial power sources for auxiliary systems.
Solution Approach 2:
The feedback current, which was previously a harmful byproduct, is now utilized to serve multiple functions - powering heating elements, seat heaters, or other electrical consumers. This multi-functional use of the feedback current allows the brake system to maintain its adaptive pressure control capabilities while simultaneously providing additional vehicle functions.
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 reduces feedback current peaks, preventing damage to electrical components and ensuring safe operation by managing feedback currents within the vehicle electrical system, allowing for efficient hydraulic pressure adjustments during multiplex operation.
Implementation Method 1
generating a feedback current by operating an electric motor (134) of the electromechanical actuator (124) as a generator
Implementation Method 2
energizing at least one electrical consumer with the feedback current
Data Source
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AI summary
The invention relates to a technique for operating an electrohydraulic motor vehicle brake system comprising a master cylinder, an electromechanical actuator for generating a hydraulic pressure on a plurality of wheel brakes and a set of electrically actuatable valve arrangements. The set of valve arrangements comprises a first valve arrangement between the master cylinder and every wheel brake. The first valve arrangements can be controlled in the multiplex operation to generate, by means of the electromechanical actuator, the respective brake pressure intended for each of the wheel brakes. According to an aspect of this technique, the method comprises the steps of: generating a feedback current during the multiplex operation by operating an electric motor of the electromechanical actuator as a generator and supplying the feedback current to at least one electrical load.