Play measuring sensor by multiple depth abrasion

• US 6,717,420 B2
• Filed: 08/01/2002
• Issued: 04/06/2004
• Est. Priority Date: 07/06/2000
• Status: Expired due to Term

• Current Assignee: Safran Aircraft Engine Company
• Original Assignee: Snecma Moteurs
• Inventors: Patrone, Franck, Eyraud, Jean-Louis
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Nguyen, Vincent Q.
• Application Number:
  US10/069,942
• Publication Number:
  US 20030020496A1
• Time in Patent Office: 614 Days
• Field of Search: 73/7, 731/16, 324/158.1, 324/691, 324/701, 324/713, 324/714, 324/715, 324/716, 324/207.11, 324/207.25, 832/71
• US Class Current: 324/701
• CPC Class Codes: F01D 11/122 with erodable or abradable material blades having cutting or grinding tips F01D5/20
• CPC Class Codes: F01D 17/02 Arrangement of sensing elements
• CPC Class Codes: G01B 7/144 Measuring play on bearings

Abstract

A device for measuring a clearance between tips of blades of a ring of blades and an interior wall of a casing surrounding the ring of blades in a turbomachine includes a probe which is mounted radially on the casing. The probe has an end made of a material that can be abraded by the tips of blades as they rotate. The device also includes a printed circuit arranged in a mid-plane of the probe. The probe contains an axis of rotation of the ring of blades. Further, the printed circuit includes a number of adjacent U-shaped electrical circuits that have bases arranged in a probe end likely to be abraded by the tips of blades. The bases lie at different depths from a reference level defining the interior wall of casing. The printed circuit also includes a recognizer for determining which U-shaped electrical circuits have been broken by abrasion and which U-shaped electrical circuits are intact.

Claims

1. A device for measuring a clearance between tips of blades of a ring of blades and an interior wall of a casing surrounding said ring of blades in a turbomachine, comprising:

a probe which can be mounted radially on the casing and at least one end of which is made of a material that can be abraded by the tips of blades as they rotate; and

a printed circuit arranged in a mid-plane of said probe, said probe containing an axis of rotation of said ring of blades,

wherein the printed circuit comprises a plurality of adjacent U-shaped electrical circuits having bases which are arranged in a probe end likely to be abraded by the tips of blades and lie at different depths from a reference level defining the interior wall of casing, and means for recognizing which U-shaped electrical circuits have been broken by abrasion and which U-shaped electrical circuits are intact.

2. The device as claimed in claim 1, wherein two adjacent U-shaped electrical circuits have a common branch.

3. The device as claimed in claim 2, wherein the depths of the bases increase by a predetermined step between a shortest lateral U-shaped electrical circuit and a longest lateral U-shaped electrical circuit.

4. The device as claimed in claim 3, wherein an outer branch of the shortest lateral U-shaped electrical circuit is connected to a first electrical terminal, and the other branches of the U-shaped electrical circuits are connected to a common second electrical terminal via a respective one of a plurality of resistors.

5. The device as claimed in claim 4, wherein the plurality of resistors have practically the same resistance.

6. The device as claimed in either of claims 4 and 5, wherein said terminals are connected to an electrical circuit external to the probe which comprises means for measuring an equivalent impedance of the resistors of the intact circuits.