SAFETY MECHANISM FOR BALL SCREW IN MEDICAL IMAGING SYSTEMS
Publication Date: 2017-May-10
The IP.com Prior Art Database
A safety mechanism for ball screw in medical imaging systems comprises a safety key, a mechanical fuse and a customized integrated key on gear hollow shaft, or a safety trapped nut component that reacts in case of fractured ball screw shank, and limits the free rotation to a small range.
The present disclosure relates generally to medical imaging, and more particularly to mechanical safety in medical imaging systems.
In normal operation, shearing of a ball screw of medical imaging systems can create condition in which heavy load (detector head) can impact patient.
Therefore, there exists a need for a technique to make available the information relating to air traffic situation implementable in a short time frame, in an inexpensive manner.
BRIEF DESCRIPTION OF DRAWINGS
FIGS. 1 and 2 depict a mechanical fuse on a gear hollow shaft according to a first embodiment.
FIGS. 3-6 depict a safety trapped nut component that reacts in case of fractured ball screw shank according to a second embodiment.
The present disclosure provides a safety mechanism for a situation in which ball screw shank has been subjected to rotational bending, which may result in fatigue fracture. A first embodiment (FIGS. 1 and 2) includes a safety key, a mechanical fuse and a customized integrated key on gear hollow shaft. A second embodiment (FIGS. 3-6) includes a safety trapped nut component that reacts in case of fractured ball screw shank, and limits the free rotation to a small range.
In the first embodiment, during normal operation, the first key transfers the moment from gear hollow shaft to a ball screw. The second safety key is positioned distal to the mechanical fuse (FIG. 1), and is not engaged during normal operation. When the ball screw is subjected to rotational bending which results in fatigue fracture, the crack due to the fracture initiates from the mechanical fuse, until the fracture is complete.
The fracture load will drive the sheared lead screw until the safety key is engaged to the hollow shaft integrated key, thereby preventing the detector load from falling on a patient. This event, also referred to as a safety event, is detected by monitoring discrepancies between motor encoder and load encoder. Upon detecting the occurrence of the safety event, the system gen...