Electric Disk Brake Parking Lock Plunger Abnormality Detection
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Solution Overview
Problem
Existing electric disk brakes with parking brake mechanisms face challenges in determining abnormalities while the brake is in operation, leading to potential unintended release of the parking brake due to mechanical lock malfunctions, especially when temperature changes affect brake pad and rotor expansion.
Innovation Solution
Incorporating a solenoid-operated plunger mechanism within the parking brake system that allows for abnormality determination by monitoring the movement of the plunger, either through electric current changes or inductance variations, to assess the solenoid and motor functionality, thereby preventing re-clamp operations during abnormal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the parking brake mechanism is re-actuated after temperature changes while the vehicle is parked, then brake force consistency is maintained, but the risk of unintended release increases due to mechanical lock malfunctions
Solution Approach 1:
The system performs preliminary abnormality determination before re-actuating the parking brake mechanism. The control apparatus checks whether the mechanical lock is functioning properly by attempting to move the plunger while the lock is engaged. Only if no abnormality is detected does the system proceed with re-actuation, thereby preventing unintended release while maintaining brake force consistency.
Solution Approach 2:
The control apparatus monitors the movement of the plunger during the locked state to detect abnormalities in the mechanical lock mechanism. This feedback mechanism allows the system to identify potential failures before they cause unintended release, enabling safe re-actuation only when the mechanical lock is confirmed to be functioning properly.
2Device complexity
If abnormality determination is performed while the brake is not in operation, then the system is simpler, but abnormality detection capability is lost during parking
Solution Approach 1:
The abnormality determination function operates continuously during the parking brake's operational state. The control apparatus continuously monitors plunger movement while the mechanical lock is engaged, ensuring abnormality detection capability is maintained throughout the parking period rather than being limited to non-operational states only.
3Measurement precision
If the plunger is constrained to prevent movement during locked state, then false abnormality detection is prevented, but solenoid malfunction detection becomes difficult
Solution Approach 1:
The system allows localized movement of the plunger specifically in the axial direction while preventing movement in other directions that would cause false abnormality detection. This selective freedom of movement enables solenoid malfunction detection through controlled plunger displacement without compromising detection accuracy, as the plunger's axial movement is monitored to identify solenoid issues.
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
Enables real-time abnormality detection and prevention of unintended parking brake releases, maintaining brake force consistency and safety by prohibiting re-clamp operations when mechanical issues are detected, thus ensuring the parking brake mechanism operates reliably.
Implementation Method 1
a parking brake mechanism operable to hold a generated brake force by causing a solenoid to move a plunger so as to actuate a lock mechanism
Implementation Method 2
The movement of the plunger may be detected based on an electric current supplied to the solenoid
Implementation Method 3
The movement of the plunger may be detected based on a change in an inductance of the solenoid
Implementation Method 4
the brake pad and the disk rotor thermally-expanded under the high temperature may be contracted due to a reduction in the temperature after a certain time has passed
Data Source
AI summary
An electric disk brake is capable of determining an abnormality of a parking brake mechanism while the parking brake mechanism is in operation. A brake force is generated in the following manner. A rotation of an electric motor is slowed down by a differential speed reducing mechanism, and is converted into a linear motion by a ball ramp mechanism so as to advance a piston, which then presses a brake pad against a disk rotor to generate a brake force. A parking brake mechanism can lock a rotation of a rotor of the electric motor and maintain a braked state by rotating an engagement pawl through a plunger of a solenoid and causing the engagement pawl to be engaged with a ratchet wheel coupled to the rotor of the electric motor. A play is provided at a coupling portion of the engagement pawl and the plunger. The play enables the plunger to move within the range of the play while the engagement pawl is engaged with the ratchet wheel, thereby enabling the determination of whether the parking brake mechanism operates normally or abnormally based on whether the plunger moves or not upon application of an electric current to the solenoid while the parking brake mechanism is in an actuated state.