Actuator Spindle Nut Jamming Detection via Current Monitoring
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Solution Overview
Problem
Conventional parking brake systems are inconvenient and pose an accident risk due to manual operation, and there is a need to detect jamming or failure of the nut spindle in electrical parking brake systems to prevent malfunctions.
Innovation Solution
An actuator and drum brake system that includes a motor-driven spindle bolt with a worm gear, spindle nut, pistons, and an O-ring to detect abnormal current patterns, triggering a safety mechanism to prevent spindle nut jamming or failure during release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual parking brake operation is used, then the driver can control the brake, but the driver must manually operate the parking lever which is inconvenient and poses accident risk due to forgetfulness
Solution Approach 1:
The parking brake system operates automatically through motor-driven actuators that engage the brake shoes without requiring driver intervention. The system serves itself by detecting parking conditions and activating the brake mechanism autonomously, eliminating the need for manual lever operation while ensuring reliable brake engagement.
2Extent of automation
If electrical parking brake with motor-driven spindle bolt is used, then automatic braking is achieved, but jamming or failure of the nut spindle cannot be detected in advance
Solution Approach 1:
A detector is integrated into the actuator to monitor the rotational position and operational status of the spindle nut in real-time. The detector provides feedback signals to the control unit, enabling continuous monitoring of the spindle nut's condition. When abnormality is detected, the control unit receives the signal and can take preventive actions, ensuring reliable operation of the automated parking brake system.
3Force
If the spindle nut is designed to engage with the spindle bolt for brake application, then braking force is generated, but the spindle nut may jam or fail during release operation
Solution Approach 1:
The detector continuously monitors the spindle nut's rotational position before release operation occurs. By detecting the precise position in advance, the system can prepare for potential release issues and activate safety mechanisms proactively. This preliminary detection prevents complete failure during the release process by enabling early intervention.
4Reliability
If a detector is added to monitor spindle nut position, then abnormal current patterns can be detected, but the device complexity increases
Solution Approach 1:
The detector serves multiple functions: it monitors the rotational position of the spindle nut, detects abnormal current patterns, and provides feedback for both diagnostic and control purposes. By integrating these multiple functions into a single detection mechanism, the system achieves reliable failure detection without proportionally increasing device complexity. The control unit also handles multiple tasks including receiving detector signals, determining abnormalities, and controlling the motor.
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 detects abnormal current patterns to activate a safety mechanism, preventing spindle nut jamming or failure and ensuring safe operation of the electrical parking brake.
Implementation Method 1
a shaft rotated by a motor and having a worm gear formed thereon
Implementation Method 2
an O-ring disposed between the spindle nut and the wheel gear
Implementation Method 3
a detector capable of detecting jamming or failure of a nut spindle in advance
Data Source
AI summary
An actuator used in a drum brake according to the present embodiment may include a case with a space therein, a shaft rotated by a motor and having a worm gear formed thereon, a wheel gear engaged with the worm gear, a spindle bolt passing through and coupled to the wheel gear and including a head and a column of which an outer circumferential surface is provided with a thread, a spindle nut fastened to the thread of the spindle bolt, a first piston of which one side is in contact with the spindle nut and the other side is in contact with the first brake shoe, a second piston of which one side is in contact with the head of the spindle bolt and the other side is in contact with the second brake shoe, and an O-ring disposed between the spindle nut and the wheel gear.