Method of and apparatus for measuring small gaps
AssigneeRenold Power Transmission Ltd.
InventorsChristopher S. Holmes, Robert G. Munro, Stanley Eastwood
Life of this patent
Estimating the term…
Abstract
A technique for measuring a small gap, in particular the clearance gap between the lobes of the rotors of a screw compressor. Light is directed through the gap, and the amount of paraxial light passing through the gap is measured, with the gap width being related to the measured amount of light. The light is directed at the pitch line helix angle into the rotor clearance gap, and the paraxial light is measured by means of an area scan camera.
Claims28
A method of measuring a gap comprising the steps of:
- (a) focusing a beam of light on the gap, which is less than 100 microns in width,
- (b) substantially eliminating non-paraxial light passing through the gap by means of telecentric filtering,
- (c) measuring the amount of substantially only paraxial light passing through the gap,
- (d) and determining the width of the gap from the measured amount of paraxial light.
A method of measuring a gap between a pair of engaged conjugate helicoids having a pitch line helix angle, said method comprising the steps of:
- (a) directing a beam of light through said gap between the pair of engaged conjugate helicoids and parallel to the pitch line helix angle,
- (b) measuring the amount of light passing through the gap, and
- (c) determining the width of the gap from the measured amount of light.
Apparatus for measuring a gap which is less than 100 microns in width, comprising:
- (a) a light projector means for generating a beam of light and focusing it on said gap which is less than 100 microns in width,
- (b) a detector system including detector means for measuring the amount of substantially only paraxial light from said light projector means falling thereon,
- (c) telecentric filtering means for intercepting non-paraxial light before it reaches the detector, and
- (d) means for determining from the measured amount of substantially only paraxial light the width of the gap located between the projector means and the detector system, the detector system including means for focusing an image of the gap on the detector means.
An apparatus for measuring a gap between a pair of engaged conjugate helicoids having a pitch line helix angle, comprising:
- (a) means for directing a beam of light through said gap between the pair of engaged conjugate helicoids and parallel to the pitch line helix angle,
- (b) means for measuring the amount of light passing through said gap, and
- (c) means for determining the width of said gap from the measured amount of light.
Apparatus for measuring a gap which is less than 100 microns in width, comprising:
- a light projector means for generating a beam of light and directing it through said gap which is less than 100 microns in width, a detector system including a detector means for measuring the amount of substantially only paraxial light from said light projector means falling thereon, and means for determining from the measured amount of paraxial light the width of said gap located between the projector means and the detector system, the detector system including means for focusing an image of the gap on the detector means;
- means for mounting a pair of engaged conjugate helicoids having a pitch line helix angle;
- means for mounting said light projection means to one side of the gap between the pair of said engaged conjugate helicoids;
- means for mounting the detector system on the other side of said gap, on a common axis with the projector means;
- and
- means for adjusting the common axis to be parallel to the pitch line helix angle of said helicoids.
Dependencies are inferred from the claim text.