Robot Joint Brake Star Geometry for Fast Stops Without Tooth Failure
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Solution Overview
Problem
Existing braking devices for robot arms, particularly in lightweight articulated robots, face issues with material failure due to high impact forces during emergency stops, leading to reduced service life and reliability.
Innovation Solution
A braking device with a brake star and bolt configuration, where the bolt engages with a radially inwardly dished impact surface on the brake star, distributing forces to reduce leverage and elastic deformation, and featuring equidistant holes to divert forces, ensuring effective energy dissipation and minimizing material fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a spring-actuated head bolt engages with radially protruding teeth of a brake star during emergency stop, then the rotor can be stopped quickly, but the high impact forces cause pronounced elastic deformation and material failure of the teeth
Solution Approach 1:
The patent applies curvature by designing the impact surface of the brake star teeth with a spherical or curved geometry that matches the bolt head. This curved surface allows the bolt to engage smoothly and distribute impact forces across a larger area, reducing stress concentration and elastic deformation during emergency braking operations.
2Power
If the impact forces between the headed bolt and the teeth are high to achieve quick stopping, then emergency brake effectiveness is improved, but this leads to pronounced elastic deformation and potential material failure
Solution Approach 1:
The patent applies preliminary action by pre-shaping the impact surface of the brake star teeth with a specific curvature radius that is at least equal to the radius of the bolt head. This preliminary geometric configuration ensures that when the bolt engages during braking, the forces are automatically distributed in a optimal pattern that maintains both high braking power and protects the tooth strength from excessive deformation.
3Reliability
If the radius of the impact surface is at least equal to the radius of the bolt to distribute forces, then elastic deformation is reduced, but the design complexity of the brake star increases
Solution Approach 1:
The patent applies parameter changes by specifying that the curvature radius of the impact surface should be at least equal to the radius of the bolt head. This parameter relationship creates an optimal force distribution geometry that enhances reliability without requiring complex additional structures. The solution transforms a geometric parameter (curvature radius) to achieve the desired force distribution and reduce elastic deformation.
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 significantly increases the service life of the braking device by reducing the risk of mechanical failure and enabling faster deceleration during emergency stops, while maintaining a lightweight and compact design suitable for human-robot collaboration.
Implementation Method 1
the forces in the web are distributed in such a way that an elastic energy dissipation takes place, which, viewed in the radial direction, exerts a reduced leverage effect on the web
Implementation Method 2
When the impact surface of the web hits the stationary bolt, the forces in the web are distributed
Implementation Method 3
a friction ring is mounted coaxially with the motor shaft, with which a pin of a locking device cooperates, in that in an emergency the pin engages radially with the friction ring
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The present invention relates, inter alia, to a brake assembly for a drive device for an articulated joint between two elements of a robot arm, which assembly comprises a brake activation device (1) and a locking element (2), wherein the brake activation device (1) is designed to bring the locking element (2) into engagement with a rotor (4) of the drive device as required to halt rotation of the rotor (4), the locking element being designed as a bolt (2) and the braking element being designed as a braking star (5) with webs (7) which have a defined impact surface (9) for the bolt (2).