JP2009244168A - Optical pyrometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pyrometer capable of performing temperature correction of a photodiode in a wide environmental temperature range. <P>SOLUTION: The pyrometer is provided with the photodiode 3 provided on the other end of an optical fiber 2 whose one end faces turbine blades, for detecting light intensity, a current-output type of temperature sensor 4 for detecting the temperature of the photodiode 3, a light intensity temperature conversion table 7 with temperature correction wherein the relation between the temperature of the turbine blades and the detection signal of the photodiode 3 is set beforehand with the temperature of the photodiode 3 used as a parameter, and an operation part 8 for finding the temperature of the turbine blades from the table 7 based on the temperature of the photodiode 3 and the detection signal of the photodiode 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical pyrometer capable of correcting the temperature of a photodiode in a wide environmental temperature range.

  An example of a pyrometer that measures the temperature of an aero engine turbine blade is an optical pyrometer that measures the temperature of the turbine blade by receiving infrared rays emitted from the turbine blade.

  An optical temperature sensor such as an optical pyrometer incorporates a photoelectric conversion element. The photoelectric conversion element converts the intensity of light (infrared rays) into a voltage signal, and is, for example, a photodiode. A photoelectric conversion element such as a photodiode has temperature dependence, and the sensitivity (the rate of change of the voltage signal with respect to the light intensity) varies depending on the temperature of the photoelectric conversion element. For this reason, the temperature of the measured object varies depending on the environmental temperature where the optical temperature sensor is placed. This is called temperature drift.

  In order to prevent this fluctuation, a temperature correction circuit using a temperature correction element is added to a general optical temperature sensor.

  As shown in FIG. 5, a conventional optical temperature sensor 41 includes a photodiode 42 that detects the light intensity of an object (not shown), and a current / voltage conversion of a detection signal of the photodiode 42 to convert the object. A current / voltage converter 43 for outputting a voltage signal representing the temperature of the object, a current output type temperature sensor 44 thermally coupled to the photodiode 42, and the current / voltage conversion via the current output type temperature sensor 44. And a gain adjusting amplifier 45 for adjusting the gain by inputting the voltage of the device 43.

  The current output type temperature sensor 44 is, for example, a thermistor.

  As described above, the temperature of the photodiode 42 is detected by the current output type temperature sensor 44 and the gain is adjusted to correct the temperature-dependent output of the photodiode 42, thereby correcting the temperature dependence of the photodiode 42. The temperature can be determined.

JP-A-11-72390

  By the way, the optical pyrometer for measuring the temperature of the turbine blade is used in a severe environmental temperature range of −54 ° C. to + 200 ° C.

  The optical temperature sensor 41 used in general factories or homes has an ambient temperature at or near normal temperature. In such a narrow temperature range, the output fluctuation due to the temperature dependence of the photodiode 42 is small, and the temperature-dependent output can be sufficiently corrected by the circuit of FIG.

  However, the optical pyrometer that measures the temperature of the turbine blade has a wide temperature range of the environmental temperature. In such a wide environmental temperature range, the temperature dependence of the photodiode is very large. Therefore, even if the circuit of FIG. 5 is applied to an optical pyrometer that measures the temperature of the turbine blade, the temperature-dependent output cannot be corrected.

  As described above, in the field of aero engines, a new optical pyrometer is desired because the ambient temperature is not found in equipment used in general factories and homes.

  On the other hand, since an optical pyrometer is mounted on an aircraft, it needs to be small and light, and a complicated one or a heavy one cannot be adopted. Therefore, it is not preferable that the circuit for correcting the output fluctuation due to the temperature dependency of the photodiode is complicated.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical pyrometer capable of solving the above problems and capable of correcting the temperature of a photodiode in a wide environmental temperature range.

  To achieve the above object, the present invention provides an optical fiber having one end facing an aero engine turbine blade, a photodiode provided at the other end of the optical fiber for detecting the light intensity of the turbine blade, A current output type temperature sensor provided along with the photodiode for detecting the temperature of the photodiode, an A / D converter for digitizing the detection signal of the photodiode, and a detection signal of the current output type temperature sensor. A / D converter that digitizes the temperature of the photodiode, and light intensity temperature conversion with temperature correction in which the relationship between the temperature of the turbine blade and the detection signal of the photodiode is set in advance using the temperature of the photodiode as a parameter Based on the table, the temperature of the photodiode and the detection signal of the photodiode By referring to the temperature compensation with light intensity temperature conversion table, in which an arithmetic unit for determining the temperature of the turbine blades.

  The two A / D converters, the light intensity temperature conversion table with temperature correction, and the calculation unit may be formed in a one-chip LSI.

  In the light intensity temperature conversion table with temperature correction, the relationship between the temperature of the turbine blade and the detection signal of the photodiode in the ambient temperature range when the temperature of the photodiode is mounted on the aircraft engine may be set.

  The present invention exhibits the following excellent effects.

  (1) The photodiode temperature can be corrected over a wide environmental temperature range.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, an optical pyrometer 1 according to the present invention includes an optical fiber 2 having one end facing a turbine blade (not shown) of an aircraft engine (see FIG. 2), and other optical fibers 2. A photodiode 3 provided at the end for detecting the light intensity of the turbine blade; a current output temperature sensor 4 provided along with the photodiode 3 for detecting the temperature of the photodiode 3; and the photodiode 3 The A / D converter 5 that digitizes the detection signal of A, the A / D converter 6 that digitizes the detection signal of the current output type temperature sensor 4 as the temperature of the photodiode 3, and the photodiode 3 Light intensity temperature conversion table with temperature correction in which the relationship between the temperature of the turbine blade and the detection signal of the photodiode 3 is set using temperature as a parameter. (Referred to as a parameter table) 7, and a calculation unit for obtaining the temperature of the turbine blade by referring to the temperature-corrected light intensity temperature conversion table 7 based on the temperature of the photodiode 3 and the detection signal of the photodiode 3. 8 and so on.

  In the present embodiment, the two A / D converters 5, 6, the light intensity temperature conversion table 7 with temperature correction, and the calculation unit 8 are formed in a one-chip LSI 9. The LSI 9 forms the arithmetic unit 8 by having a CPU and memory on which desired software can be mounted, or a digital arithmetic processing circuit network that can be customized to a desired circuit configuration. The LSI 9 includes a plurality of channels of A / D converters and a plurality of channels of D / A converters. This built-in A / D converter is used as A / D converters 5 and 6. One of the built-in D / A converters is used as a D / A converter 10 for outputting the temperature (numerical value) of the turbine blade obtained by the calculation unit 8 to the outside as an analog temperature output signal. Yes. As LSI 9, PSoC (registered trademark) of Cypress Semiconductor, which is a one-chip microcomputer incorporating an A / D converter and a D / A converter, may be used.

  The photodiode 3 is connected to the input terminal of the current / voltage converter 11, and the output terminal of the current / voltage converter 11 is connected to the A / D converter 5. The current output type temperature sensor 4 is connected to the input terminal of the current / voltage converter 12, and the output terminal of the current / voltage converter 12 is connected to the A / D converter 6.

  As shown in FIG. 2, the optical pyrometer 1 according to the present invention includes a sensor head portion 21 and a circuit portion 22. One end of the optical fiber 2 is accommodated in the sensor head portion 21. The sensor head unit 21 is inserted into the aircraft engine 23 from the outside of the aircraft engine 23. The sensor head unit 21 is fixed inside the aero engine 23 with one end of the optical fiber 2 facing a turbine blade (not shown).

  The optical fiber 2 is routed outside the aircraft engine 23 and wired to the circuit unit 22. The other end of the optical fiber 2 is fixed in the circuit unit 22. The circuit unit 22 accommodates the photodiode 3, the current output temperature sensor 4, the LSI 9, and the like shown in FIG. The circuit unit 22 is attached to the outer wall of the aircraft engine 23.

  FIG. 3 shows a processing flow in the LSI 9 of the optical pyrometer 1.

  In step S1, the output X of the photodiode 3 is captured. The output X is, for example, an analog amount that changes in the range of 0 to 5V. In step S2, the output X is converted into a physical quantity x. The physical quantity x is a digital quantity of current expressed in units of μA, for example.

  On the other hand, in step S3, the temperature Y of the photodiode 3 (the temperature of the current output type temperature sensor 4) Y is captured. The temperature Y is an analog amount that varies within a range of 0 to 5 V, for example. In step S4, the temperature Y is converted into a physical quantity y. The physical quantity y is a digital quantity of temperature expressed in units of K, for example.

  In step S5, the light source temperature (turbine blade temperature) f (x, y) is calculated. The light source temperature f is a digital quantity of temperature expressed in K units, for example. In step S6, output unit conversion is performed. For example, the output F is an analog amount obtained by converting the light source temperature f into a voltage (unit: V).

  In step S7, an offset voltage Z is prepared. The offset voltage Z is, for example, an analog amount of unit V. In step S8, the output F and the offset voltage Z are added.

  In the processing flow of FIG. 3, the calculation performed in step S5 may use an arithmetic expression representing the temperature dependence characteristic of the photodiode 3, or based on this temperature dependence characteristic, the physical quantity x, the physical quantity y, A map in which the light source temperature f is associated may be prepared in advance in the light intensity temperature conversion table 7 with temperature correction, and the light source temperature f may be obtained by searching this map with the physical quantity x and the physical quantity y.

  FIG. 4 is a graph showing the relationship between the temperature of the turbine blade and the detection signal (current) of the photodiode 3 using the temperature of the photodiode 3 as a parameter. The current value was 1 when the turbine blade temperature was 1000 ° C. and the photodiode temperature was 25 ° C. This graph is digitized (discretized) and set in the light intensity temperature conversion table 7 with temperature correction. The temperature range of the photodiode 3 as a parameter is preferably the environmental temperature range on the outer wall of the aircraft engine 23 in which the circuit unit 22 is installed.

  The operation of the optical pyrometer 1 of the present invention will be described.

  One end of the optical fiber 2 accommodated in the sensor head portion 21 faces the turbine blade inside the aircraft engine 23. Radiated light whose light intensity varies with temperature is emitted from the turbine blade, and the emitted light is incident on the optical fiber 2. The emitted light transmitted through the optical fiber 2 is incident on the photodiode 3 of the circuit unit 22 attached to the outer wall of the aircraft engine 23.

  The photodiode 3 generates electric power that is substantially proportional to the light intensity of incident light (however, it depends on temperature). The current is converted into a voltage by the current / voltage converter 11 and becomes a received light output voltage, that is, a detection signal indicating the light intensity of the turbine blade. This detection signal is input to the LSI 9. The detection signal of the light intensity of the turbine blade is digitized by the A / D converter 5 in the LSI 9 and the numerical value is temporarily stored in the calculation unit 8.

  On the other hand, the current output type temperature sensor 4 generates a current that varies depending on the temperature of the photodiode 3. The current is converted into a voltage by the current / voltage converter 12 and becomes a detection signal indicating the temperature of the photodiode 3. This detection signal is input to the LSI 9. The detection signal of the temperature of the photodiode 3 is digitized by the A / D converter 6 in the LSI 9 and the numerical value is temporarily stored in the arithmetic unit 8.

  In the calculation unit 8, the light intensity temperature conversion table 7 with temperature correction is referred to based on the temperature of the photodiode 3 and the detection signal of the photodiode 3 (detection signal indicating the light intensity of the turbine blade).

  In the light intensity temperature conversion table 7 with temperature correction, the relationship between the temperature of the turbine blade and the detection signal of the photodiode 3 in the environmental temperature range when the temperature of the photodiode 3 is installed in the aircraft engine is set in advance as a numerical value. Yes. Therefore, when the calculation unit 8 refers to the light intensity temperature conversion table 7 with temperature correction based on the temperature of the photodiode 3 and the detection signal of the photodiode 3, the temperature of the turbine blade is obtained.

  The turbine blade temperature value output from the calculation unit 8 is converted into an analog temperature output signal by the D / A converter 10 and output to the outside.

  According to the present invention, the current output type temperature sensor 4 is arranged in the vicinity of the photodiode 3, the output of the photodiode 3 and the output of the current output type temperature sensor 4 are digitized, and the numerical value based on the temperature dependence of the photodiode 3. Therefore, the temperature of the turbine blade is measured without depending on the environmental temperature.

  Further, according to the present invention, the arithmetic unit 8 is realized by a one-chip microcomputer with an A / D converter and a D / A converter, so that the circuit configuration is simplified and the weight is reduced, which is suitable for an aircraft. A small and light optical pyrometer 1 is provided.

  In addition, according to the present invention, since the calculation unit 8 is realized by a one-chip microcomputer, even when using photodiodes having different temperature dependencies, fine adjustment (calibration) can be performed by software partial change or light intensity with temperature correction. This can be easily handled by rewriting the temperature conversion table 7.

  In addition, according to the present invention, since the data of the wide ambient temperature range when the temperature of the photodiode 3 is mounted on the aero engine is written in the light intensity temperature conversion table 7 with temperature correction, it is applied to an aero engine having a wide environmental temperature range. can do.

It is a block diagram of the optical pyrometer which shows one Embodiment of this invention. It is the side view which showed the one side of the centerline of the aircraft engine which attached the optical pyrometer of FIG. 2 is a flowchart of processing executed by the LSI of the optical pyrometer of FIG. It is a characteristic graph which shows the temperature dependence of a photodiode. It is a block diagram of the conventional optical temperature sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical pyrometer 2 Optical fiber 3 Photodiode 4 Current output type temperature sensor 5, 6 A / D converter 7 Light intensity temperature conversion table with temperature correction 8 Arithmetic unit 9 LSI
DESCRIPTION OF SYMBOLS 10 D / A converter 11 Current / voltage converter 12 Current / voltage converter 21 Sensor head part 22 Circuit part 23 Aviation engine

Claims (3)

  An optical fiber having one end facing the turbine blade of an aircraft engine, a photodiode provided at the other end of the optical fiber for detecting the light intensity of the turbine blade, and the photodiode provided along with the photodiode A current output temperature sensor for detecting the temperature of the photodiode, an A / D converter for digitizing the detection signal of the photodiode, and an A / D for digitizing the detection signal of the current output temperature sensor as the temperature of the photodiode. A D converter, a light intensity temperature conversion table with temperature correction in which the relationship between the temperature of the turbine blade and the detection signal of the photodiode is set in advance using the temperature of the photodiode as a parameter, the temperature of the photodiode, and the photo Light intensity temperature conversion table with temperature correction based on diode detection signal By reference to a optical pyrometer, characterized in that an arithmetic unit for determining the temperature of the turbine blades.   2. The optical pyrometer according to claim 1, wherein the two A / D converters, the light intensity temperature conversion table with temperature correction, and the calculation unit are formed in a one-chip LSI.   In the light intensity temperature conversion table with temperature correction, the relationship between the temperature of the turbine blade and the detection signal of the photodiode in the ambient temperature range when the temperature of the photodiode is installed in the aircraft engine is set. The optical pyrometer according to claim 1 or 2.

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