Electromechanical Drum Brake Actuator Stop for Compact Quiet Release
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Solution Overview
Problem
Current electric parking brake systems lack precision in controlling the relative position of mechanical elements during the release phase, leading to bulkier designs and increased noise due to imprecision and dimensional inaccuracies, which affect braking time and driver comfort.
Innovation Solution
Incorporating a mechanical stop within the actuator that allows precise positioning of movable elements, eliminating the need for error margins and allowing for a more compact design by accurately determining the stop position, thereby reducing brake application time and noise duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the brake is designed without a mechanical stop and relies on estimation of component positions, then the design is simpler, but the positioning precision deteriorates and the brake size increases due to required safety margins
Solution Approach 1:
The mechanical stop structure serves dual purposes: it provides the stopping function and simultaneously defines the precise position reference for the piston. The stop is integrated into the actuator body, eliminating the need for separate positioning sensors or complex feedback mechanisms, thereby achieving self-service functionality that improves precision without proportionally increasing complexity
Solution Approach 2:
The mechanical stop is pre-positioned at a known location within the actuator, establishing a predetermined reference point before the braking operation begins. This preliminary positioning allows the control system to know exactly where the piston will be when it contacts the stop, enabling precise calculation of the remaining stroke distance without requiring complex real-time measurement systems
2Reliability
If safety margins are increased to account for positioning inaccuracy, then the reliability improves, but the brake size and application time increase
Solution Approach 1:
The patent replaces the traditional approach of using large mechanical safety margins with a precision mechanical stop that provides exact positioning. The stop mechanically defines the endpoint with high accuracy, allowing the control system to use smaller time and distance margins while maintaining reliability, thus reducing brake application time without sacrificing safety
Solution Approach 2:
The invention changes the critical parameter from an estimated position with large uncertainty bounds to a precisely defined position at the mechanical stop. By controlling the piston movement to stop exactly at the known stop position rather than relying on current/voltage estimates, the system reduces the required safety margins in both time and distance, thereby reducing overall brake application time while maintaining or improving reliability
3Reliability
If the actuator stroke is extended to account for positioning uncertainty, then the reliability improves, but the noise duration increases
Solution Approach 1:
The mechanical stop provides a clear, unambiguous feedback signal to the control system when the piston reaches the predetermined position. This tactile feedback allows the control system to stop the actuator motor precisely at the stop point, eliminating the need to extend the stroke beyond the actual required distance. Consequently, the actuator operates for a shorter duration, reducing noise emission while maintaining reliability through precise positioning
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 solution enhances control precision, reduces the brake's size, shortens the brake application time, and minimizes noise and inconvenience to the driver and passengers by accurately determining the position of movable elements, allowing for optimized actuator dimensions and reduced travel distance.
Implementation Method 1
an actuator with an electric motor is located at least on each rear brake, and causes the brakes to be applied
Implementation Method 2
said actuator comprising at least one mechanical stop, said actuator being controlled in the brake release phase so that at least one of the movable elements of the actuator comes to bear against the stop
Implementation Method 3
apply a braking force to an element integral in rotation with a wheel
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Electromechanical drum brake comprising two brake segments (3, 4) intended to come into contact with a drum, and at least one actuator (110) configured to apply the segments (3, 4) against the drum, and an electric motor (22) configured to activate the actuator (110), the actuator (110) comprising at least one member (18) which is movable upon activation of the actuator (110), the movable member (18) being movable between a braking position and a position beyond a release position, in which the segments are no longer in contact with the drum. The actuator (110) comprises a stop (126) which is arranged only in the actuator and against which the movable element (18) bears when it assumes a position beyond the release position, and the motor powers the actuator until the movable element (18) bears against the stop (126).