# US 8,571,831 B2 · Determination of the gap size of a radial gap > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,571,831 B2 - Document ID: US8571831B2 - Status: Granted - Kind: B2 - Application number: 12/878,224 - Filed: 2010-09-09 - Published: 2010-12-30 - Granted: 2013-10-29 - Earliest claimed: 2004-07-12 - Assignees: Siemens Aktiengesellschaft - Applicants: Uwe Pfeifer; Michael Zidorn - Inventors: Uwe Pfeifer; Michael Zidorn - Web page: https://patentgrep.com/patent/US8571831B2 ## CPC - G01S 13/58: Velocity or trajectory determination systems; Sense-of-movement determination systems - F01D 11/14: Adjusting or regulating tip-clearance, i.e. distance between rotor-blade tips and stator casing (rotors with blades adjustable in operation F01D7/00) - G01B 15/00: Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons (characterised by the use of optical techniques G01B9/00, G01B11/00) - G01B 17/00: Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations - G01S 13/88: Radar or analogous systems specially adapted for specific applications (electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00) - G01S 15/58: Velocity or trajectory determination systems; Sense-of-movement determination systems {(velocity measurement in imaging systems G01S15/8979)} - F05D 2220/32: in gas turbines - F05D 2260/80: Diagnostics - F05D 2270/309: Rate of change of parameters - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A method for determining the size of a radial gap between rotating and torsion-proof parts, particularly the parts of a turbomachine is provided. According to the method, an original signal emitted by a transmitter device located on the surface of the rotating part is received in a modified manner by a receiver device disposed on the torsion-proof part and is redirected to an evaluation unit. The evaluation device determines and displays the size of the radial gap from the received signal by determining the parameters of the trajectory of the rotating transmitter device. ## Claims ### Claim 1 A method for determining a radial gap size between a rotating component and a stationary component of a continuous-flow machine, comprising: emitting a source signal as a radio wave from a transmitting device arranged on a surface of the rotating component; receiving a modified form of the source signal by a receiving device arranged on the stationary component; transferring the modified source signal to an evaluation device; determining parameters of a path curve of the rotating transmitting device by the evaluation device based on the modified source signal; and determining the gap size of the radial gap via the evaluation device based on the previously determined parameters of the path curve of the rotating transmitting device. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein the signals are radio-frequency electromagnetic waves at a frequency in a range between 0.5 MHz and 100 GHz. ### Claim 3 (depends on 2) The method as claimed in claim 2, wherein the signals are radio-frequency electromagnetic waves at a frequency in a range between 1 GHz and 10 GHz. ### Claim 4 (depends on 1) The method as claimed in claim 1, wherein the evaluation device evaluates a field strength or an intensity of the received signal to determine the parameters of the path curve. ### Claim 5 (depends on 1) The method as claimed in claim 1, wherein the evaluation device evaluates a frequency shift of the received signal due to a Doppler effect. ### Claim 6 (depends on 5) The method as claimed in claim 5, wherein the evaluation device filters out a Doppler frequency from the received signal by frequency demodulation. ### Claim 7 (depends on 6) The method as claimed in claim 6, wherein the radial gap size is determined from a time duration of the Doppler frequency. ### Claim 8 An apparatus for determining a radial gap between a rotating component and a stationary component of a continuous-flow machine, comprising: a transmitting device for emitting a source signal as a radio frequency wave, wherein the transmitting device is arranged on the rotating component; a receiving device for receiving a modified form of the source signal, wherein the receiving device is arranged on the stationary component; and an evaluation device communicatively coupled to the receiving device, and wherein the evaluation device is configured for determining parameters of a path curve of the rotating transmitting device based on the modified source signal, and wherein the evaluation device is further configured for determining the gap size of the radial gap based on the previously determined parameters of the path curve of the rotating transmitting device. ### Claim 9 (depends on 8) The apparatus as claimed in claim 8, wherein the signals are radio-frequency electromagnetic waves at a frequency in a range between 0.5 MHz and 100 GHz. ### Claim 10 (depends on 9) The apparatus as claimed in claim 9, wherein the signals are radio-frequency electromagnetic waves at a frequency in a range between 1 GHz and 10 GHz. ### Claim 11 (depends on 8) The apparatus as claimed in claim 8, wherein the evaluation device evaluates a field strength or an intensity of the received signal to determine the parameters of the path curve. ### Claim 12 (depends on 8) The apparatus as claimed in claim 8, wherein the evaluation device evaluates a frequency shift of the received signal due to a Doppler effect. ### Claim 13 (depends on 12) The apparatus as claimed in claim 12, wherein the evaluation device filters out a Doppler frequency from the received signal by frequency demodulation. ### Claim 14 (depends on 13) The apparatus as claimed in claim 13, wherein the radial gap size is determined from a time duration of the Doppler frequency. ### Claim 15 (depends on 8) The apparatus as claimed in claim 8, wherein the transmitting device is supplied with energy through an inductive coupling with the stationary component. ### Claim 16 (depends on 8) The apparatus as claimed in claim 8, wherein the transmitting device is supplied with energy through a battery, wherein the battery is arranged on the rotating component. ### Claim 17 (depends on 8) The apparatus as claimed in claim 8, wherein the transmitting device and receiving device comprise a transmitting antenna and a receiving antenna respectively, wherein each of the transmitting and the receiving antennas has a point beam or a linear beam characteristic. ### Claim 18 (depends on 8) The apparatus as claimed in claim 8, wherein the rotating component is a rotor of the continuous flow machine, and the stationary component is a free-standing stator blade opposite the rotor.