Brake Piston Control for Smooth Single-Pedal Deceleration
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Solution Overview
Problem
In vehicles with a single-pedal function, drivers experience an unexpected increase in counter force when using the secondary actuating element to increase deceleration due to pre-defined hydraulic piston displacement, leading to an unusual and undesirable driving experience.
Innovation Solution
A method that dynamically adjusts the first deceleration value upon detection of the secondary actuating element's actuation, temporarily decreasing it to match the expected counter force, ensuring a consistent driving experience by reducing the counter force required to increase deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the braking force generator is activated to displace the hydraulic piston according to the first deceleration value, then the motor vehicle is decelerated as expected, but the counter force increases excessively when the driver actuates the second actuating element
Solution Approach 1:
The patent dynamically adjusts the first deceleration value based on the actuation state of the second actuating element. When the second actuating element is actuated, the control unit reduces the first deceleration value temporarily, allowing the hydraulic piston displacement to be reduced or reversed. This dynamic adjustment resolves the contradiction by making the deceleration system adaptive to driver input rather than fixed, thereby maintaining reliability while improving ease of operation.
2Productivity
If the hydraulic piston is already displaced by the braking force generator, then deceleration is achieved, but the driver must overcome greater counter force to increase deceleration further
Solution Approach 1:
The control unit continuously monitors the actuation state of the second actuating element and uses this feedback to adjust the first deceleration value in real-time. When the driver actuates the second actuating element, the system detects this input and responds by reducing the first deceleration value, thereby reducing the counter force the driver must overcome. This feedback mechanism resolves the contradiction by creating a responsive system that adapts to driver needs while maintaining deceleration efficiency.
3Reliability
If the first deceleration value is maintained constant, then consistent deceleration control is achieved, but the driving experience becomes unusual and uncomfortable
Solution Approach 1:
The patent changes the parameter of the first deceleration value from a constant to a variable that depends on the actuation state of the second actuating element. By temporarily reducing the first deceleration value when the second actuating element is actuated, the system maintains deceleration consistency during normal operation while improving driving comfort during active braking, thus resolving the contradiction between reliability and ease of operation.
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
The method ensures that the counter force required to increase deceleration aligns with the driver's expectations, providing a more comfortable and familiar driving experience by minimizing the unexpected increase in counter force.
Implementation Method 1
a braking system including an activatable braking force generator and a master brake cylinder, in which at least one hydraulic piston is displaceably mounted
Implementation Method 2
When the hydraulic piston is displaced, a deceleration torque decelerating the motor vehicle is generated
Implementation Method 3
Such a braking force generator includes an electric motor, which is coupled by a gearbox device to the hydraulic piston in such a way that the hydraulic piston is displaceable by the electric motor
Implementation Method 4
The counter force is provided by a spring element, which is compressed during actuation of the second actuating element by the driver
Data Source
AI summary
A method for operating a motor vehicle. The motor vehicle includes a first actuating element, an actuatable second actuating element, and a braking system including an activatable braking force generator and a master brake cylinder, at least one hydraulic piston displaceably mounted in the master brake cylinder and is steplessly displaceable between first and second end positions. A first deceleration value is predefined for the motor vehicle when the instantaneous position of the piston falls short of a change position between the first and second ends. The braking force generator, when the first deceleration value is predefined, is activated in such a way that the hydraulic piston is displaced as a function of a level of the first deceleration value. The first deceleration value is decreased upon detection of the actuation of the second actuating element by the driver.