Cable-Pull Parking Brake Release via Motor Current Feedback
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Solution Overview
Problem
Existing cable-pull systems for parking brakes lack precise identification of the release maneuver completion, often resulting in unsafe and slow release operations due to residual torques, especially in electrically controlled systems.
Innovation Solution
A cable-pull actuation system with a body housing an electric motor, a rod, transmission means, and pre-loading means, including a control unit that monitors current absorption to suspend power supply when a defined limit is exceeded, ensuring precise release and preventing residual torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors are used to control the release operation, then the release operation becomes slower, but the identification of release completion becomes more precise
Solution Approach 1:
The patent replaces position sensors with a current-based detection system. The control unit monitors current absorption of the electric motor during the releasing step, and suspends power supply when a predefined current limit is exceeded, indicating release completion. This substitutes the mechanical/electrical sensing system with an electrical current monitoring system, achieving both precision and speed.
2Productivity
If the electric motor continues to supply current during the releasing step, then the release maneuver can be completed, but residual torque may remain causing safety issues
Solution Approach 1:
The control unit continuously monitors the current absorption of the electric motor during the releasing step. When the current exceeds a predefined limit value, the control unit suspends power supply to the motor, precisely identifying the end of the release maneuver. This feedback mechanism ensures complete brake disengagement without residual torque by dynamically adjusting motor operation based on real-time current measurements.
3Device complexity
If pre-loading means are not provided, then the system structure is simpler, but load variations and thermal overload conditions cannot be compensated
Solution Approach 1:
The pre-loading means are pre-loaded by a pusher to exert a pre-load traction on the rod before operation begins. This preliminary action compensates for load variations and thermal overload conditions during parking brake operation, ensuring reliable performance across different operating conditions without requiring complex active control systems.
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 enables quick, effective, and reliable release of the parking brake, ensuring safety by precisely identifying the end of the release maneuver and preventing residual torque, with the pre-loading means compensating for load variations and thermal overload conditions.
Implementation Method 1
pre-loading means, which are compressively pre-loaded by a pusher so as to exert a pre-load traction on the rod to offset variations of load on the rod
Implementation Method 2
body which houses electric motor means
Implementation Method 3
transmission means, which operatively connect the electric motor means to a second end of the rod which is translationally integral with a screw having a thread, in which said screw is engaged, by means of the thread, with a nut screw
Data Source
AI summary
A cable-pull actuation system for a parking brake may have a body which houses an electric motor device. A rod, adapted to operate along an actuation direction, at a first end thereof, an actuation member of a drum brake and/or of a parking brake. A transmission device may operatively connect the electric motor device to a second end of the rod which is translationally integral with a screw. The screw may be engaged with a nut screw rotationally actuated by the transmission device. A pre-loading device may act in contrast on the screw. The pre-loading device may be compressively pre-loaded to exert a pre-load traction on the rod to offset variations of load on the rod. The pre-loading device may be configured to exert a thrust action on the rod following the annulment of axial clearances for an incremental compression of the pre-loading device with respect to the pre-load value.