Variable Pressure Thresholds for Regenerative Brake Pump Control
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Solution Overview
Problem
In vehicles with regenerative brake systems, using a low-pressure pump as the sole supplier results in a lower overload point for the brake force booster, reducing the ability to generate adequate brake force, especially at critical braking speeds, compared to systems with an internal combustion engine.
Innovation Solution
The first and second predefined low-pressure levels in the low-pressure chamber are adjusted based on vehicle speed, with the motor pump unit being activated or deactivated accordingly, allowing increased pressure at critical braking speeds to match the performance of an internal combustion engine-based system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a low-pressure pump is used as the sole low pressure supplier in regenerative brake systems, then the system can operate without an internal combustion engine, but the overload point of the brake force booster becomes much lower, reducing brake force generation capability
Solution Approach 1:
The patent applies dynamics by making the switch-on and switch-off pressure levels variable rather than fixed. The electronic control unit adjusts these pressure thresholds dynamically based on vehicle operating conditions, allowing the system to optimize brake force booster performance across different driving scenarios while maintaining adequate brake force generation capability.
Solution Approach 2:
The patent changes the pressure parameters (switch-on and switch-off levels) adaptively based on vehicle speed and operating conditions. By modifying these critical parameters, the system compensates for the lower overload point limitation and maintains adequate brake force generation capability across different operating regimes.
2Force
If the motor pump unit is activated frequently to maintain pressure, then adequate brake force is maintained, but the service life of the motor pump unit is reduced
Solution Approach 1:
The patent modifies the pressure threshold parameters (switch-on and switch-off levels) based on vehicle speed and operating conditions. By raising the switch-off pressure level at higher speeds, the system reduces the frequency of pump activation cycles, thereby extending motor pump unit service life while maintaining adequate brake force output when needed.
Solution Approach 2:
The patent implements a periodic control strategy where the motor pump unit operates in cycles based on pressure thresholds. By adaptively adjusting these thresholds, the system optimizes the periodic action to balance brake force maintenance with reduced pump wear and extended service life.
3Force
If the low-pressure level is increased at critical braking speeds, then the overload point matches that of internal combustion engine systems, but the motor pump unit experiences higher load cycles
Solution Approach 1:
The patent applies dynamics by making the pressure thresholds variable based on vehicle speed. At critical braking speeds, the system raises the switch-off pressure level to maintain high overload point performance. The dynamic adjustment ensures that increased load cycles occur only when necessary for safety, balancing performance requirements with energy consumption.
Solution Approach 2:
The patent changes the pressure parameters adaptively based on vehicle operating conditions. By raising the switch-off pressure level at higher speeds, the system maintains adequate brake force generation capability while minimizing unnecessary pump operation and associated energy consumption during normal driving conditions.
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 ensures the brake force booster's overload point is maintained at levels comparable to systems with an internal combustion engine, reducing the load cycles and overall running time of the motor pump unit, while preventing continuous operation and extending its service life.
Implementation Method 1
a pneumatic motor pump unit for creating the low pressure in the low-pressure chamber, which motor pump unit includes a low-pressure pump
Implementation Method 2
a low-pressure level in the low-pressure chamber or a pressure difference between the low-pressure chamber and the working chamber being detected by means of a sensor
Data Source
AI summary
A method for creating low pressure in a brake activation device of a motor vehicle brake system, comprising a pneumatic brake force booster the interior of which is divided into at least one low-pressure chamber and one working chamber, a brake master cylinder and a pneumatic motor pump unit for creating the low pressure in the low-pressure chamber, which motor pump unit comprises a low-pressure pump and a motor driving the low-pressure pump, a low-pressure level in the low-pressure chamber or a pressure difference between the low-pressure chamber and the working chamber being detected by a sensor and the motor pump unit being activated by an electronic control unit if the pressure falls below a first predefined, lower low-pressure level Pe in the low-pressure chamber and being deactivated if a second predetermined, upper low-pressure level Pa is reached.