Source: http://www.google.com/patents/US6761528?ie=ISO-8859-1
Timestamp: 2014-07-13 00:10:52
Document Index: 613264158

Matched Legal Cases: ['art 9', 'art 11', 'art 13', 'art 13', 'art 13', 'art 11', 'art 9', 'art 9', 'art 11', 'art 13', 'art 13']

Patent US6761528 - Steam turbine and method of measuring the vibration of a moving blade in a ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsThe invention relates to a steam turbine (3) comprising an optical measuring system (60) for measuring a moving blade vibration. A transmitter (55) produces a light beam (61) which strikes the moving blades (27, 29, 31, 33) and is reflected by these into a receiver (57). By providing that the transmitter...http://www.google.com/patents/US6761528?utm_source=gb-gplus-sharePatent US6761528 - Steam turbine and method of measuring the vibration of a moving blade in a flow passage of a steam turbineAdvanced Patent SearchPublication numberUS6761528 B2Publication typeGrantApplication numberUS 10/169,147PCT numberPCT/EP2001/010599Publication dateJul 13, 2004Filing dateSep 13, 2001Priority dateSep 14, 2000Fee statusPaidAlso published asDE50014498D1, EP1189044A1, EP1189044B1, US20030118442, WO2002023141A1Publication number10169147, 169147, PCT/2001/10599, PCT/EP/1/010599, PCT/EP/1/10599, PCT/EP/2001/010599, PCT/EP/2001/10599, PCT/EP1/010599, PCT/EP1/10599, PCT/EP1010599, PCT/EP110599, PCT/EP2001/010599, PCT/EP2001/10599, PCT/EP2001010599, PCT/EP200110599, US 6761528 B2, US 6761528B2, US-B2-6761528, US6761528 B2, US6761528B2InventorsFrank WoditschkaOriginal AssigneeSiemens AktiengesellschaftExport CitationBiBTeX, EndNote, RefManPatent Citations (15), Non-Patent Citations (1), Referenced by (3), Classifications (8), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetSteam turbine and method of measuring the vibration of a moving blade in a flow passage of a steam turbineUS 6761528 B2Abstract The invention relates to a steam turbine (3) comprising an optical measuring system (60) for measuring a moving blade vibration. A transmitter (55) produces a light beam (61) which strikes the moving blades (27, 29, 31, 33) and is reflected by these into a receiver (57). By providing that the transmitter (55) is separated from the receiver (56), the invention achieves a measuring angle that actually reduces the scattered light effect of the steam enough to enable reliable optical measurements of the blades vibration. The invention also relates to a method for measuring the vibration of a moving blade (33) in a flow channel (19, 21, 23, 25) of a steam turbine (3).
3. The steam turbine as claimed in claim 1, wherein the transmitter and receiver are arranged such that the transmitted light beam and the reflected light beam enclose an angle of reflection of at least 45� with one another.
4. The steam turbine as claimed in claim 3, wherein the angle of reflection is at least 90�.
directing a light beam onto a moving blade, the light beam being reflected from the moving blade at an angle of reflection greater than 45�; directing the reflected light beam to a receiver; and calculating the blade vibration from the received reflected light beam, wherein the light beam is directed onto a reflecting surface on the moving blade, in such a way that the illuminated part of the reflecting surface is less than 50 mm2.
9. The method as claimed in claim 8, wherein the angle of reflection is greater than 90�.
15. The measuring system as claimed in claim 13, wherein the transmitter and receiver are arranged such that the transmitted light beam and the reflected light beam enclose an angle of reflection of at least 45� with one another.
16. The measuring system as claimed in claim 15, wherein the angle of reflection is at least 90�.
This application is the national phase under 35 U.S.C. � 371 of PCT International Application No. PCT/EP01/10599 which has an International filing date of Sep. 13, 2001, which designated the United States of America and which claimed priority on European application No. EP 00120036.9 filed Sep. 14, 2000, the entire contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION The invention generally relates to a steam turbine having a flow passage in which a moving blade is arranged. More preferably, it relates to one including a measuring system for measuring a vibration of the moving blade. The invention also generally relates to a method of measuring the vibration of a moving blade in a flow passage of a steam turbine.
BACKGROUND OF THE INVENTION The technical field of the invention is the measurement of blade vibrations in fluid-flow machines. Moving blades in fluid-flow machines are subjected to high loads. A vibration may be induced in them on account of alternating stresses, this vibration, if it lies in the vicinity of a natural vibration in the respective blade, leading to especially high mechanical stresses of this blade. In order to detect such especially high loads in good time, the vibration states of the blades are measured in different ways.
In the paper �A Review of Analysis Techniques for Blade Tip Timing Measurements�, S. Heath, M. Imregum, ASME publication 97/GT/218, presented at the International Gas Turbine and Aeroengine Congress and Exhibition, Orlando, Fla., USA, May 2, 1997, a method of measuring the blade vibration by means of a laser is described. However, this method relates solely to gas turbines.
SUMMARY OF THE INVENTION Accordingly, an object of an embodiment of the invention is to specify a steam turbine in which the measurement of the vibration of a moving blade is possible in a non-contact and reliable manner largely independent of properties of the moving blade. A further object of an embodiment of the invention is to specify a corresponding method of measuring the vibration of a moving blade.
The transmitter and receiver are preferably arranged in such a way that the transmitted light beam and the reflected light beam enclose an angle of reflection of at least 45� with one another. The angle of reflection is also preferably greater than 90�. In such a large-angled arrangement, a good ratio of light beam reflected directly into the receiver to scattered radiation caused in the steam is obtained, since the proportion of scattered radiation drops with a larger angle.
The moving blade is preferably made of a non-magnetic material. The moving blade is also preferably made of a titanium-based alloy. Here, the expression �non-magnetic� means that the material of the moving blade has no appreciable ferromagnetic properties. Especially in the case of such a material, a simple non-contact measurement by means of magnetic induction is ruled out. Such a material is, for example, a titanium-based alloy, which are used in new generations of steam turbines, in particular when the moving blades of the last stages of low-pressure parts are very large. However, such large blades especially are susceptible to vibration excitation and are loaded to a considerable extent by vibrations. Here, especially, a reliable monitoring system for measuring the blade vibration states must therefore be used. By means of the optical monitoring of the blade vibrations, this is also possible for such blades in a simple and reliable manner.
According to an embodiment of the invention, an object which relates to a method may be achieved by a method of measuring the vibration of a moving blade in a flow passage of a steam turbine, a light beam being directed onto the moving blade and being reflected from the latter at an angle of reflection greater than 45� and directed to a receiver, and the blade vibration being calculated from the signal thus received.
The angle of reflection is preferably greater than 90�. The light beam used is preferably a laser beam.
BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained in more detail by way of example with reference to the drawings. In the drawings, partly schematically and not to scale:
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a steam turbine 3. A high-pressure part 9, an intermediate-pressure part 11 and a double-flow low-pressure part 13 are arranged one behind the other on a common shaft 5 between bearings 7. The double-flow low-pressure part 13 consists of a first low-pressure half 15 and a second low-pressure half 17. The low-pressure part 13 has a low-pressure casing 14. The intermediate-pressure part 11 has an intermediate-pressure casing 12. The high-pressure part 9 has a high-pressure casing 10. The high-pressure part 9 has a high-pressure flow passage 19. The intermediate-pressure part 11 has an intermediate-pressure flow passage 21. The low-pressure part 13 has a first low-pressure flow passage 23 in the first low-pressure half 15 and a second low-pressure flow passage 25 in the second low-pressure half 17. Moving blades 27 are arranged in successive moving-blade rings in the high-pressure flow passage 19. Intermediate-pressure moving blades 29 are arranged in successive moving-blade rings in the intermediate-pressure flow passage 21. Moving blades 31 are arranged in successive moving-blade rings in the low-pressure flow passage 23 of the first low-pressure half 15. Moving blades 33 are arranged in successive moving-blade rings in the low-pressure flow passage 25 of the second low-pressure half 17 of the low-pressure part 13.
FIG. 2 shows a detail of the second low-pressure half 17 of FIG. 1. A measuring system 60 is arranged in the low-pressure casing 14. The measuring system 60 includes a transmitter 55 and a receiver 57. A light beam 61, formed by a laser beam, is directed by the transmitter 55 into the flow passage 25 and onto a moving blade 33. The moving blade 33 has a shroud band 51 which has a bevelled reflecting surface 53 toward the transmitter 55. From the reflecting surface 53, the light beam 61 is directed as reflected light beam 63 to the receiver 57. The transmitter 55 and the receiver 57 are separated from one another in such a way that an angle x greater than 90� is obtained between the incident light beam 61 and the reflected light beam 63. On the reflecting surface 53, the light beam 61 illuminates a part area 65 which is less than 1 mm2.
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