Patents by Inventor Christoph Liebtrau

Christoph Liebtrau has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method and apparatus for testing an elevator speed limiter
    Patent number: 5717175
    Abstract: An apparatus for testing a speed limiter in an elevator installation includes a drive wheel engaging a cable groove of a cable guide roller in the speed limiter. The drive wheel is rotated by rotational device having a speed control for linearly increasing the speed of rotation of the cable guide roller until the speed limiter is triggered. The rotation of the drive wheel is detected by an evaluating device attached to the rotational device and having an opti-electronic system for generating a light beam toward reflectors on the drive wheel and detecting reflected light beams. The triggering instant of the speed limiter is detected by an acceleration sensor connected to the evaluating device which then calculates the triggering speed from the speed of the drive wheel at the triggering instant.
    Type: Grant
    Filed: March 6, 1996
    Date of Patent: February 10, 1998
    Assignee: Inventio AG
    Inventors: Christoph Liebtrau, Hanspeter Mattli