Drum Brake Linear Actuator Stop Ring for Early Torque Detection
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Solution Overview
Problem
Existing linear drum brake actuators face challenges in reducing the time during which the motorization exerts torque after the nut has reached the stop position, potentially causing damage due to the reaction time of the computer system.
Innovation Solution
A linear drum brake actuator design featuring a movable ring with an elastic member that cooperates with protrusions on the fixed stop, allowing the computer to detect resistive torque variations earlier and initiate stopping before the nut abuts, thereby reducing the duration of motorization action at the stop position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the computer waits to detect the stop position by monitoring current fluctuations until the nut reaches the stop position, then the detection is accurate, but the reaction time causes the motorization to continue exerting torque and potentially damage components
Solution Approach 1:
The elastic member is positioned to contact the stop position before the nut reaches it, creating an early warning signal through current fluctuation. This preliminary action allows the computer to detect the approaching stop position in advance and initiate reverse rotation before the nut makes harmful contact, thus resolving the contradiction between accurate detection and timely response.
2Loss of time
If the elastic member contacts the stop position early to provide warning, then the reaction time is reduced, but the duration of motorization action at the stop position is still insufficiently reduced
Solution Approach 1:
The protrusion on the stop position creates an even earlier contact point with the elastic member, providing a second stage of preliminary warning. This allows the computer to initiate stopping action before the elastic member even contacts the main stop surface, further reducing the duration of harmful motorization action and improving reliability.
3Reliability
If the computer initiates stopping immediately upon detecting elastic member contact, then the component damage risk is reduced, but the stopping action may occur before the nut is close enough to the stop position
Solution Approach 1:
The system uses continuous monitoring of current fluctuations as feedback to track the nut's approach to the stop position. The computer integrates this feedback information with the timing of elastic member contact to determine the optimal moment to initiate reverse rotation, ensuring both component protection and accurate stop position achievement.
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 design enables more precise anticipation and prevention of nut abutment, minimizing the time the motorization exerts torque after reaching the stop position, thus reducing the risk of component damage.
Implementation Method 1
the elastic member (46) cooperates with an associated portion (38) of the fixed abutment (22) when the ring (24) is located in an actuation position located axially between the abutment position and a predefined actuation position, to produce an opposing resistive torque
Data Source
Figure 1~3
Figure 4A~4B
Figure 5~6A
AI summary
The invention proposes a linear actuator for a drum brake of a vehicle, in particular a motor vehicle, which comprises an electric drive; and a stop device (20) comprising a fixed stop (22) and a movable ring (24) which bears an elastic member (46) which cooperates with an associated portion (38) of the fixed stop (22), in which the electric drive comprises a computer for detecting variations in the electric current supplying the electric drive as a function of the value of said resistant torque, the fixed stop (22) comprising at least one protuberance (52) with which the elastic member (46) cooperates when the ring (24) is in at least one other predefined actuating position situated at a distance from and upstream of the predefined actuating position in order to produce a variation in a resistant torque when said at least one protuberance (52) is crossed by the elastic member (46).