Wrap Spring Clutch for Selective Self-Locking in Electromechanical Brakes
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Solution Overview
Problem
Existing electromechanically actuated motor vehicle brakes often require complex designs with self-locking gear arrangements, limiting their use as both service and parking brakes, and may unintentionally release the parking brake effect due to reaction forces.
Innovation Solution
Incorporating a wrap spring clutch in the power flow between the motor drive and spindle, which allows torque transmission to the spindle for actuation while blocking torque transmission from the spindle to the motor drive, preventing unintentional release and allowing the brake to function as both a service and parking brake without additional switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-locking gear arrangement is used to prevent unintentional release of parking brake effect, then reliability of parking brake is improved, but the brake cannot be used as service brake because it blocks torque transmission in both directions
Solution Approach 1:
The gear arrangement transitions from a static self-locking design to a dynamic system using a wrap spring clutch that automatically adjusts its torque transmission characteristics based on the direction and magnitude of applied torque, enabling the same mechanism to serve both parking brake and service brake functions
Solution Approach 2:
A wrap spring clutch is introduced as an intermediary element between the motor drive and the spindle, serving as a smart coupling that selectively transmits or blocks torque based on operational conditions, thereby resolving the contradiction between reliability and versatility
2Reliability
If a self-locking worm gear is used to maintain parking brake effect, then parking brake reliability is improved, but device complexity increases due to additional blocking devices and switching elements
Solution Approach 1:
The wrap spring clutch is designed to automatically perform the blocking function without requiring external control systems, sensors, or additional switching elements. The clutch engages or disengages based purely on the mechanical torque conditions, making the system self-regulating and eliminating complex control architecture
Solution Approach 2:
The gear arrangement with wrap spring clutch serves multiple functions: it transmits torque during service braking, maintains parking brake effect through automatic blocking, and eliminates the need for separate blocking devices, thereby reducing overall system complexity while enhancing versatility
3Adaptability or versatility
If a wrap spring clutch is used to allow torque transmission from motor drive to spindle while blocking reverse torque, then brake versatility is improved, but manufacturing complexity may increase
Solution Approach 1:
The wrap spring clutch utilizes conventional, easily manufactured components such as coil springs and friction surfaces that are simple to produce and replace, avoiding the need for complex electronic control systems or specialized materials, thereby maintaining ease of manufacture while achieving enhanced functionality
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 wrap spring clutch ensures reliable torque transmission for actuation and blocks reaction forces, enabling the brake to function as both a service and parking brake, preventing unintentional release and reducing the need for additional switching elements.
Implementation Method 1
the wrap spring clutch transmits torque from the motor drive allows to the spindle
Implementation Method 2
the wrap spring clutch is designed to block a torque transmission from the spindle to the motor drive
Data Source
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AI summary
The invention relates to a motor vehicle brake, in particular an electromechanically actuable motor vehicle brake, having an actuator assembly (10) comprising: a housing (12), an actuating element (18), which is movable relative to the housing (12), for displacing a brake lining, a motor drive (22), a movement mechanism arranged between the motor drive (22) and the movable actuating element (18), and a gearbox arrangement (26) assigned to the movement mechanism, wherein the movement mechanism has a ball screw (28) with a spindle (76) which can be driven in rotation and with a nut (86) which is movable linearly in the housing (12), wherein in order to move the actuating element (18), the nut (86) can be moved within the housing (12) by virtue of the spindle (76) being driven in rotation. It is provided in said motor vehicle brake that the gearbox arrangement (26) has a wrap spring coupling (70) which is arranged in the power flow between the motor drive (22) and the spindle (76) in such a way that the wrap spring coupling (70) permits a transmission of torque from the motor drive (22) to the spindle (76) and is designed to block a transmission of torque from the spindle (76) to the motor drive (22).