Patent US4346383A successfully refreshed from Google Patents.
US4346383A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Checking the location of moving parts in a machine
Assignee: EMI Ltd
•
Filing: 1980-08-01
•
Granted: 1982-08-24
•
Expires: 2000-08-01
Abstract
Abstract In order to monitor the clearance between turbine blades and the casing of a turbine engine millimetric microwave radiation of wavelength λ is propagated along a waveguide and through an aperture to a turbine blade. The aperture is small in relation to the area of the blade facing the aperture, and the aperture has a spacing of λ/4 or less from the blade. A balanced mixer compares the phase of the wave reflected from the blade with a reference pulse to provide a measure of the clearance. Circuits may be provided for monitoring the spacings between blades, and to indicate blades which are damaged.
Inventors
- 👤 Sydney C. Woolcock
- 👤 Edwin G. Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:17
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/88
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
178 words
In a turbine engine comprising a set of turbine blades extending radially of an axis of rotation and a casing surrounding the set, the improvement of means for monitoring the clearance between the blades and the casing comprising: means for producing electromagnetic waves of millimetric wavelength λ having a reference phase, a waveguide fixed relative to the casing and having an aperture facing the said set of turbine blades, and spaced therefrom by λ/4 or less, the area of the aperture being small in relation to the radially facing cross-sectional area of any one of the said blades, the waveguide and aperture being dimensioned to allow the said waves to propagate from the producing means through the aperture, a phase detector coupled to the producing means and the waveguide to produce a signal, dependent on the phase difference between the said reference phase and the phase of the reflected waves, and further means for producing a further signal representing the amplitude of the reflected waves, thereby to indicate the presence of a blade in proximity to the waveguide.
Claim 2
Dependent Claim
178 words
In a turbine engine comprising a set of turbine blades extending radially of an axis of rotation and a casing surrounding the set, the improvement of means for monitoring the clearance between the blades and the casing comprising: means for producing electromagnetic waves of millimetric wavelength λ having a reference phase, a waveguide fixed relative to the casing and having an aperture facing the said set of turbine blades, and spaced therefrom by λ/4 or less, the area of the aperture being small in relation to the radially facing cross-sectional area of any one of the said blades, the waveguide and aperture being dimensioned to allow the said waves to propagate from the producing means through the aperture, a phase detector coupled to the producing means and the waveguide to produce a signal, dependent on the phase difference between the said reference phase and the phase of the reflected waves, and further means for producing a further signal representing the amplitude of the reflected waves, thereby to indicate the presence of a blade in proximity to the waveguide.
Claim 3
Dependent Claim
15 words
A turbine engine according to claim 1, wherein the phase detector comprises a balanced demodulator.
Claim 4
Dependent Claim
49 words
A turbine engine according to claim 1 or claim 2, wherein the phase detector comprises a hybrid T junction having a shunt arm connected to the waveguide to receive the reflected waves and a series arm connected to the producing means to receive the wave having the reference phase.
Claim 5
Dependent Claim
139 words
Apparatus for monitoring the clearance between a set of turbine blades extending radially of an axis of rotation and a casing in a turbine engine, comprising: means for causing electromagnetic waves of millimetric wavelength λ to propagate from a datum position fixed relative to the casing to the zone occupied by the blades, and means for deriving a measure of the clearance from the propagating waves reflected by the blades and from an electromagnetic wave of the said wavelength and having a reference phase, wherein the casing comprises a waveguide having an aperture which is small in relation to the radially facing cross-sectional area of any one of the turbine blades, and wherein further means are connected for receiving the reflected waves and producing therefrom blade pulses indicative of the presence of blades in the proximity of the aperture.
Claim 6
Dependent Claim
139 words
Apparatus for monitoring the clearance between a set of turbine blades extending radially of an axis of rotation and a casing in a turbine engine, comprising: means for causing electromagnetic waves of millimetric wavelength λ to propagate from a datum position fixed relative to the casing to the zone occupied by the blades, and means for deriving a measure of the clearance from the propagating waves reflected by the blades and from an electromagnetic wave of the said wavelength and having a reference phase, wherein the casing comprises a waveguide having an aperture which is small in relation to the radially facing cross-sectional area of any one of the turbine blades, and wherein further means are connected for receiving the reflected waves and producing therefrom blade pulses indicative of the presence of blades in the proximity of the aperture.
Claim 7
Dependent Claim
63 words
Apparatus according to claim 4, further comprising means having an input for receiving timing signals indicative of the period of rotation of the said set of turbine blades, and another input for receiving the said blade pulses, the means being adapted to compare an interval between successive ones of the said blade pulses with a predetermined fraction of the said period of rotation.
Claim 8
Dependent Claim
40 words
Apparatus according to claim 5, comprising a reference pulse generator having an input for receiving the timing signals, and adapted to produce reference pulses having a repetition rate which is a preselectable multiple of the period of the timing signals.
Claim 9
Dependent Claim
32 words
Apparatus according to claim 6, further comprising means responsive to the blade pulses and the reference pulses to produce signals indicative of the differences in timing of the blade and reference pulses.
Claim 10
Dependent Claim
27 words
Apparatus according to claim 7, further comprising means for selecting those signals indicative of differences in timing of the blade and reference pulses exceeding a selectable amount.
Claim 11
Dependent Claim
29 words
Apparatus according to claim 4, 5, 6, 7 or 8, further comprising means for producing a gating pulse at a selectable time after the reception of a timing signal.
Claim 12
Dependent Claim
48 words
Apparatus according to claim 9, further comprising means responsive to the blade pulses, the reference pulses and the gating pulses to produce a signal indicative of the time interval between the occurrence of a blade pulse and a reference pulse occurring within the duration of the gating pulse.
Claim 13
Independent Claim
125 words
A method of monitoring the clearance between turbine blades and a casing in a turbine engine comprising propagating electromagnetic waves of millimetric wavelength λ from a datum position fixed relative to the casing to the zone occupied by the blades and deriving a measure of the clearance from the propagating waves reflected by the blades and from an electromagnetic wave of the said wavelength and having a reference phase, wherein the waves are propagated via a waveguide having an aperture facing the blades, which is small in relation to the cross-sectional area facing the aperture of any one of the blades when adjacent the aperture, and producing, from the reflected waves, blade pulses indicative of the presence of blades in the proximity of the aperture.
Claim 14
Independent Claim
125 words
A method of monitoring the clearance between turbine blades and a casing in a turbine engine comprising propagating electromagnetic waves of millimetric wavelength λ from a datum position fixed relative to the casing to the zone occupied by the blades and deriving a measure of the clearance from the propagating waves reflected by the blades and from an electromagnetic wave of the said wavelength and having a reference phase, wherein the waves are propagated via a waveguide having an aperture facing the blades, which is small in relation to the cross-sectional area facing the aperture of any one of the blades when adjacent the aperture, and producing, from the reflected waves, blade pulses indicative of the presence of blades in the proximity of the aperture.
References Cited (Backward Citations)
US3199103A
Cited
GB1277748A
Cited
US3973259A
Cited
US4045727A
Cited
GB1545656A
Cited
US4200921A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-08-23 | 1986-02-22 | 1986-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-08-23 | 1990-02-22 | 1990-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-08-23 | 1994-02-22 | 1994-08-24 | $7700.00 | Window Closed / Lapsed |