Electric Parking Brake Inclination Detection
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Solution Overview
Problem
Conventional electric parking brake systems face challenges in accurately determining road inclination, leading to delayed activation of the hill hold function, especially in low-speed scenarios, which can result in inadequate braking force settings, particularly on slopes and during engine stalls.
Innovation Solution
An electric parking brake control apparatus that includes an inclination determination unit using vehicle speed changes and an acceleration sensor to set appropriate braking forces, activating the hill hold function with a slope braking force even without immediate inclination determination, and switching to flat ground braking when accuracy is established, ensuring adequate braking force settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a G sensor is used to detect inclination for hill hold function, then the braking force can be adjusted according to road slope, but the inclination determination accuracy deteriorates during vehicle deceleration due to deceleration G interference, causing a time lag of about 2 seconds before accurate inclination can be determined after stopping
Solution Approach 1:
The system performs preliminary action by determining inclination during the vehicle running state (when vehicle speed is not zero) using the relationship between vehicle speed change and longitudinal G, and stores this determined inclination value for use after the vehicle stops, avoiding the need to determine inclination again after stopping when measurement accuracy would be poor
Solution Approach 2:
The system dynamically switches between two inclination determination methods: during running state, it uses the dynamic method based on vehicle speed change and longitudinal G; after stopping, it uses the stored inclination value from the running state. This dynamic switching resolves the contradiction by using the appropriate method for each operational phase
2Loss of time
If the vehicle speed sensor is used to determine inclination by comparing vehicle speed change with longitudinal G, then inclination can be determined quickly after stopping, but it becomes impossible to determine inclination accurately when the vehicle stops again after running only in low-speed range without experiencing no low-speed running
Solution Approach 1:
The system performs preliminary action by determining inclination during the vehicle running state (when vehicle speed is not zero) using the relationship between vehicle speed change and longitudinal G, and stores this determined inclination value for use after the vehicle stops, avoiding the need to determine inclination again after stopping
Solution Approach 2:
The system provides beforehand cushioning by having a backup mechanism: when the dynamic determination method cannot be used (vehicle stopped without prior running), the system can determine inclination after a predetermined time has elapsed since stopping, cushioning against the inability to determine inclination in low-speed stop scenarios
3Reliability
If a large braking force is set to prevent vehicle movement on steep slopes, then the hill hold function can effectively prevent unintentional movement, but the load on the electric parking brake apparatus and energy consumption increase
Solution Approach 1:
The system changes the braking force parameter dynamically based on the determined road inclination: on steeper slopes, a larger braking force is applied; on gentler slopes, a smaller braking force suffices. This parameter adaptation resolves the contradiction by optimizing braking force to the minimum necessary for each specific slope condition
Solution Approach 2:
The system dynamically adjusts the braking force according to the determined inclination angle, making the braking force adaptive to the actual road conditions rather than using a fixed large braking force, thereby reducing unnecessary energy consumption while maintaining hill hold effectiveness
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 system effectively activates the hill hold function more accurately and reliably, even in conditions where inclination determination is uncertain, optimizing braking force settings and enhancing vehicle safety on slopes and during engine stalls.
Implementation Method 1
an acceleration (G) sensor as an inclination sensor for detecting the inclination of a road surface
Implementation Method 2
a vehicle speed sensor, and a relationship between a change of the vehicle speed and a longitudinal G is determined
Data Source
AI summary
An electric parking brake control apparatus for controlling an electric actuator for driving a parking brake is provided with: an inclination determination unit for determining an inclination of a road surface based on at least a change of a vehicle speed; and a braking force setting unit. The braking force setting unit sets a braking force of the parking brake to a slope braking force which is larger than a flat ground braking force set when the vehicle is stopped on a flat ground, according to an inclination of the road surface which is determined by the inclination determination unit. Moreover, in the event that the vehicle is stopped again without experiencing a running over a predetermined vehicle speed after braking with the slope braking force has been cancelled, the braking force setting unit sets the braking force to the slop braking force.