Bi-Stable Wrap Spring Actuator for Power-Failure Locking
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Solution Overview
Problem
Traditional park brake systems require regular maintenance due to wear and contamination, and electric motor actuators for braking systems face challenges in maintaining a stable locking mechanism without continuous power supply.
Innovation Solution
A bi-stable electric motor actuator with a wrap spring park brake system that uses a combination of magnets, a stator, and a rotor cup to create a magnetic reluctance torque, allowing for a self-locking mechanism that reduces load on the actuator and maintains the brake engaged even without power, utilizing a control unit to manage the engagement and disengagement of the park brake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional spring-based park brake system is used, then the brake can be engaged and disengaged through mechanical manipulation, but the system requires regular maintenance due to wear and contamination
Solution Approach 1:
The patent replaces the traditional mechanical spring-based park brake system with an electromagnetic actuator system. The electromagnetic actuator uses magnetic fields to engage and disengage the park brake, eliminating mechanical wear components like springs and friction-based mechanisms. This substitution of mechanical systems with electromagnetic systems directly addresses the maintenance issue while managing the complexity through integrated design.
2Reliability
If an electric motor actuator is used to replace the park brake system, then maintenance needs are reduced, but the actuator requires continuous power supply to maintain the locking mechanism
Solution Approach 1:
The electromagnetic actuator is designed to consume power only periodically during engagement and disengagement operations, rather than continuously. Once the park brake is engaged, the mechanism maintains its locked state through mechanical self-locking features, allowing the actuator to remain unpowered. This periodic action principle reduces energy consumption significantly compared to continuous power requirements.
Solution Approach 2:
The park brake system incorporates self-locking mechanical features that maintain the engaged state without requiring continuous external power or active control. The system uses its own mechanical structure to sustain the locked position, making it self-sufficient after the initial engagement action, thereby eliminating ongoing energy consumption.
3Reliability
If a bi-stable wrap spring park brake system is used, then the brake remains engaged without power and maintenance is reduced, but the system occupies more space and mass
Solution Approach 1:
The patent combines the electromagnetic actuator with the wrap spring park brake mechanism into an integrated assembly. By merging these components, the design achieves stable locking without continuous power while minimizing the overall mass and space occupation. The combined system leverages the strengths of both electromagnetic actuation and mechanical self-locking without requiring separate, redundant components.
Solution Approach 2:
The design employs a nested arrangement where the electromagnetic actuator is positioned within or adjacent to the wrap spring mechanism, and components are arranged concentrically or in space-efficient configurations. This nesting approach minimizes the overall footprint and mass of the stationary object while maintaining the bi-stable locking capability.
4Device complexity
If a traditional friction-based park brake is used, then the system is simple in structure, but it is susceptible to wear and contamination affecting performance
Solution Approach 1:
The patent replaces friction-based mechanical components with electromagnetic actuation mechanisms. The electromagnetic actuator uses magnetic fields to generate force, eliminating the need for friction-based engagement and disengagement. This substitution removes the friction surfaces that are susceptible to wear and contamination, directly addressing the harmful factors while managing structural complexity through the electromagnetic system.
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 cost-effective, reliable, and compact bi-stable locking system that reduces maintenance needs and occupies less space and mass compared to traditional systems, while ensuring the brake remains engaged when power is not available, thus enhancing operational efficiency and safety.
Implementation Method 1
uses a combination of magnets, a stator, and a rotor cup to create a magnetic reluctance torque
Implementation Method 2
bi-stable wrap spring park brake system that uses a combination of magnets, a stator, and a rotor cup to create a magnetic reluctance torque, allowing for a self-locking mechanism
Data Source
Figure 1A
Figure 1B~1D
Figure 2
AI summary
An electric motor actuator (10), comprising a shaft (16); a spring (60) installed around the shaft (16), the spring (60) comprising a first spring tang (62) and a second spring tang (64); a rotor cup (40) rotatably installed about at least a portion of the shaft (16), the rotor cup (40) configured to receive the second spring tang (64); a magnet (30) coupled to the rotor cup (40); a stator (20) comprising a coil (22), wherein the rotor cup (40) rotates in response to the coil (22) biasing the magnet (30), and wherein the spring (60) tightens on the shaft (16) in response to the rotor cup (40) rotating.