Parking Brake Control Using Motor Current for Pedal Comfort
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Solution Overview
Problem
Existing brake systems using non-electric boosters, such as negative-pressure boosters, fail to effectively suppress uncomfortable feelings towards brake pedal reaction forces when the electric parking brake mechanism is actuated, as they lack the ability to control hydraulic pressure changes.
Innovation Solution
A control apparatus that includes a hydraulic mechanism and a parking brake mechanism with an electric motor, where a control portion acquires physical amounts related to current changes, hydraulic pressure, or brake pedal strokes during application operations, and sets a second physical amount indicating completion to be smaller when the first physical amount exceeds a threshold, determining the completion of the application operation based on these values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an electric booster is used to compensate for hydraulic pressure changes during parking brake actuation, then the uncomfortable feeling toward brake pedal reaction force is suppressed, but the system complexity increases and compatibility with non-electric boosters is lost
Solution Approach 1:
The parking brake mechanism itself generates the signal (current change) that triggers the completion determination, eliminating the need for external sensors or complex control systems. The system uses its own operational characteristics to self-regulate the application process.
Solution Approach 2:
The patent replaces the electric booster's active hydraulic pressure compensation mechanism with a passive control strategy that monitors current changes and adjusts the application completion threshold accordingly, eliminating the need for complex electro-hydraulic control systems.
2Device complexity
If a non-electric booster (negative-pressure booster) is used, then the system structure is simpler, but the ability to suppress uncomfortable feelings toward brake pedal reaction force is lost
Solution Approach 1:
The control portion continuously monitors the current applied to the electric motor and uses this feedback to determine when to complete the application operation. The feedback loop adjusts the application completion threshold based on real-time current changes, enabling comfort optimization without complex hardware.
Solution Approach 2:
The patent dynamically changes the second physical amount (application completion threshold) based on the first physical amount (current change). This parameter adjustment allows the system to adapt to different operating conditions and suppress uncomfortable pedal reactions without requiring a different booster type.
3Reliability
If the application completion threshold is set high, then the parking brake applies fully, but the brake pedal reaction force becomes uncomfortable during actuation
Solution Approach 1:
The application completion threshold is not fixed but dynamically adjusted based on real-time current monitoring. The system transitions from a static threshold approach to a dynamic one, allowing the threshold to change during the application process to balance holding force and comfort.
Solution Approach 2:
The control portion monitors current changes from the beginning of the application operation and uses this information to determine the optimal completion point in advance, rather than using a fixed threshold that causes discomfort. The system prepares for completion determination by continuously tracking current trends.
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 effectively suppresses uncomfortable feelings towards brake pedal reaction forces regardless of the brake system configuration, by reducing the current threshold value when the brake pedal is pressed, thereby maintaining vehicle stoppage without complicating the system configuration.
Implementation Method 1
a parking brake mechanism configured to hold the braking force by an electric motor controlled by a control portion
Implementation Method 2
a hydraulic mechanism configured to provide a braking force to a vehicle by pressing a frictional member against a rotational member rotating together with a wheel based on a hydraulic pressure
Implementation Method 3
pressing a frictional member against a rotational member rotating together with a wheel
Data Source
AI summary
A parking brake control apparatus acquires a first physical amount indicating a change in a current applied to an electric motor (for example, a gradient of a change in a current) at the time of an application operation. The parking brake control apparatus sets a second physical amount indicating completion of the application operation so as to make it smaller when the first physical amount (for example, the gradient of the change in the current) exceeds a predetermined threshold value, compared to when the first physical amount is equal to or smaller than the threshold value. The parking brake control apparatus determines the completion of the application operation when a physical amount indicating the application operation (for example, a current value) reaches the second physical amount.