Patents by Inventor Esa Lehtovirta

Esa Lehtovirta 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 equipment for attenuation of oscillation in a paper machine or in a paper finishing device
    Patent number: 6911117
    Abstract: A method and apparatus for damping vibration in a paper machine. The apparatus having a dynamic damper which includes a weight suspended by a spring. The spring constant of the spring is changed by means of a control device in order to tune the natural frequency of the dynamic damper. The dynamic damper is tuned to a frequency that is substantially equal to a multiple of the rotational frequency of the roll in the paper machine that is being damped.
    Type: Grant
    Filed: April 22, 1998
    Date of Patent: June 28, 2005
    Assignee: Metso Paper, Inc.
    Inventors: Jouko Karhunen, Arto Puranen, Jorma Köliö, Esa Lehtovirta, Erkki Hietamäki
  • Apparatus for preventing vibrations of a roll set
    Patent number: 5915297
    Abstract: An apparatus for reducing or preventing vibrations of a roll set of a paper making apparatus, wherein the roll set comprises at least two rolls of which at least one is a soft roll coated with a compressible coating and comprising a temperature control system. The natural vibrational frequency of the roll set is changed during the operation of the apparatus by changing the temperature of the coating of the at least one soft roll. The changing of the natural frequency prevents resonance on a natural frequency of the roll set.
    Type: Grant
    Filed: December 10, 1997
    Date of Patent: June 29, 1999
    Assignee: Valmet Corporation
    Inventors: Esa Lehtovirta, Jorma Kolio, Markku Salo, Kari Luostarinen
  • Method for preventing vibrations of a roll set
    Patent number: 5768985
    Abstract: A method for reducing or preventing vibrations of a roll set of a paper making apparatus, wherein the roll set comprises at least two rolls of which at least one is a soft roll coated with a compressible coating and comprising a temperature control system. The natural vibrational frequency of the roll set is changed during the operation of the apparatus by changing the temperature of the coating of at least one soft roll. The changing of the natural frequency prevents resonance on a natural frequency of the roll set.
    Type: Grant
    Filed: December 11, 1995
    Date of Patent: June 23, 1998
    Assignee: Valmet Corporation
    Inventors: Esa Lehtovirta, Jorma Kolio, Markku Salo, Kari Luostarinen