Wrap Spring Brake Actuator Locking for Compact Parking Brakes
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Solution Overview
Problem
Existing electromechanical vehicle brakes face challenges in efficiently integrating a parking brake function without increasing space requirements or costs, while maintaining a compact design and energy-efficient operation.
Innovation Solution
A brake actuator with a locking assembly using a wrap spring coaxially arranged with the output shaft, which is tightened to block the shaft rotationally, utilizing frictional forces to prevent brake release, eliminating the need for additional mechanical components and allowing for a compact, energy-efficient parking brake mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking mechanism with additional mechanical components (such as locking pawls or carriages) is used to implement parking brake function, then the reliability of brake locking is improved, but the device complexity and space requirements increase
Solution Approach 1:
The invention extracts and eliminates unnecessary mechanical locking components (locking pawls, carriages) from the brake system. The parking brake function is achieved solely through the frictional force of the wrap spring acting on the output shaft, removing complex mechanical locking elements while maintaining reliable brake holding capability.
Solution Approach 2:
The invention replaces traditional mechanical locking mechanisms with a friction-based wrapping spring system. Instead of using mechanical interlocking components, the solution uses the friction between the wrap spring and output shaft to prevent rotation, substituting complex mechanical systems with a simpler friction-based mechanism.
2Strength
If additional mechanical components are added to the locking assembly to ensure secure parking brake engagement, then the strength of locking is improved, but the space requirement and manufacturing costs increase
Solution Approach 1:
The invention merges the parking brake locking function with the existing output shaft and wrap spring components. The wrap spring serves dual purposes: it provides the actuating force for brake engagement and simultaneously provides the frictional locking force for parking brake function, eliminating the need for separate locking components and reducing overall assembly space.
Solution Approach 2:
The output shaft and wrap spring are designed to perform multiple functions: they serve both as the actuating mechanism for service brake engagement and as the locking mechanism for parking brake function. This multi-functionality eliminates the need for additional dedicated locking components, reducing space and cost.
3Reliability
If a complex locking mechanism with multiple mechanical elements is used, then the reliability of preventing brake release is improved, but the energy consumption and operational complexity increase
Solution Approach 1:
The wrap spring system is self-sustaining and requires no external energy input to maintain the locked state. Once the brake is engaged, the frictional force of the wrap spring automatically prevents reverse rotation and brake release without requiring continuous power input or complex control mechanisms, making the system energy-efficient and self-regulating.
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 solution provides a compact, cost-effective, and energy-efficient parking brake function by leveraging the wrap spring's frictional forces, reducing space requirements and operational costs, while ensuring reliable brake engagement and hot retensioning without additional mechanical actuation.
Implementation Method 1
the friction between the windings of the wrap spring and the output shaft increases to a sufficient extent that a rotation of the output shaft is completely prevented
Implementation Method 2
The windings of the wrap spring are radially expanded again until a release position of the wrap spring is reached, in which the frictional forces are sufficiently reduced that the output shaft can freely rotate
Data Source
AI summary
A brake actuator for an electromechanical vehicle brake has a locking assembly (40) for selectively rotationally blocking an output shaft (42) to form a parking brake function. The locking assembly (40) comprises a wrap spring (44) and a drive (70), wherein the windings (46) of the wrap spring (44) are arranged coaxially with the output shaft (42) and the locking assembly (40) is configured and arranged such that the drive (70) can tighten the wrap spring (44) about the output shaft (42) into a locked position in order to block the output shaft (42). After the electromechanical vehicle brake (10) is closed, the wrap spring (44) is tightened into the locked position so that the output shaft (42) is blocked. For a hot retensioning of the vehicle brake, the output shaft (42) is rotated in a rotational direction increasing the brake force, whereby the wrap spring (44) is loosened. The vehicle brake is reset in the rotational direction increasing the brake force and the output shaft (42) is released again, whereby the wrap spring (44) is tightened again.