ONBOARD DEVICE AND METHOD FOR ANALYZING FLUID IN A HEAT ENGINE

• US 20150346085A1
• Filed: 12/04/2013
• Published: 12/03/2015
• Est. Priority Date: 12/07/2012
• Status: Active Grant

• Current Assignee: SP3H
• Original Assignee: SP3H
• Inventors: OBERTI, Sylvain, FOURNEL, Johan
• Granted Patent: US 9,562,850 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 2021/3181 using LEDs
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 2201/062 LED's
• CPC Class Codes: G01N 2201/0624 Compensating variation in output of LED source
• CPC Class Codes: G01N 2201/121 Correction signals
• CPC Class Codes: G01N 2201/1211 for temperature
• CPC Class Codes: G01N 2201/124 Sensitivity
• CPC Class Codes: G01N 2201/1242 Validating, e.g. range invalidation, suspending operation
• CPC Class Codes: G01N 2201/1247 Thresholding
• CPC Class Codes: G01N 2201/127 Calibration; base line adjustment; drift compensation
• CPC Class Codes: G01N 2201/12723 Self check capacity; automatic, periodic step of checking

Abstract

A method for controlling a spectrometer for analyzing a product includes steps of: acquiring a measurement representative of the operation of a light source, determining, depending on the measurement, a value of supply current of the light source, and/or a value of integration time of light-sensitive cells of a sensor, disposed on a route of a light beam emitted by the light source and having interacted with a product to be analyzed, and if the integration time and/or supply current value is between threshold values, supplying the light source with a supply current corresponding to the determined supply current value, adjusting the integration time of a light-sensitive cell to the determined integration time value, and acquiring light intensity measurements supplied by the sensor, enabling a spectrum to be formed.

Claims

1. A method for controlling a spectrometer for analyzing a product, comprising steps of sending a light beam from a light source of the spectrometer, of transmitting the light beam to a product to be analyzed with which it interacts, and of acquiring light intensity measurements enabling a spectrum to be formed, by means of a sensor of the spectrometer, disposed on a route of the light beam after it has interacted with the product to be analyzed,

the acquisition of light intensity measurements comprising steps of:

acquiring in the presence of the product to be analyzed measurements representative of the operation of the light source and independent of the product to be analyzed, the operation measurements comprising a measurement of the temperature of the light source, and

determining, depending on the operation measurements, a value of supply current of the light source, and if the supply current value is within an ideal operating range, supplying the light source with a supply current corresponding to the determined supply current value, and/or

determining, depending on the operation measurements, a value of integration time of light-sensitive cells of the sensor, and if the integration time value is between threshold values, adjusting the integration time of the light-sensitive cells to the determined integration time value.

2. Method according to claim 1, wherein a new value of the supply current of the light source is determined and a supply current corresponding to the determined supply current value is supplied to the light source, as long as an integration time value of light-sensitive cells of the sensor is not between the threshold values.

3. Method according to claim 1, wherein the measurements representative of the operation of the light source comprise a measurement of light intensity directly produced by the light source, and/or a measurement of the light source supply current intensity and/or voltage.

4. Method according to claim 1, comprising self-diagnosis test steps comprising at least one of the following comparisons:

comparisons to determine whether the measurements representative of the operation of the light source are consistent with each other, and comparisons of supply current supplied to the light source with minimum and maximum values, and if one of the comparisons reveals a defect, the spectrometer is switched to a degraded or default operating mode.

5. Method according to claim 1, comprising a step of correcting the light intensity measurements taking account of a difference between the temperature of the product to be analyzed and/or between the temperature of the sensor with a reference temperature, so as to obtain corrected light intensity measurements resulting from measurements taken at the reference temperature, the corrected measurements forming a corrected spectrum.

6. Method according to claim 1, wherein the light source comprises several light-emitting diodes having distinct spectra covering an analysis wavelength band, the method comprising successive steps of switching on each of the light-emitting diodes, of obtaining a corrected spectrum for each diode, and of summing the corrected spectra obtained while applying weighting factors, to obtain a resulting spectrum.

7. Method according to claim 6, comprising a step of averaging several resulting spectra, the number of averaged spectra being increased when an operating mode of the spectrometer switches from a normal to a degraded state.

8. Method according to claim 1, including a calibration of the spectrometer, comprising:

steps of determining minimum and maximum match values for matching measurements of light intensity directly produced by the light source with supply current setpoint values of the light source and/or with the temperature of the light source, and/or

steps of determining minimum and maximum supply current setpoint values of the light source, and/or

steps of determining minimum and maximum values of integration time of the light-sensitive cells of the sensor, and/or

steps performed in the presence of one or more reference products, of determining a function supplying an optimal integration time of a light-sensitive cell of the sensor according to a light intensity produced by the light source, and/or

steps performed in the presence of one or more reference products, during which the temperature of the light source and/or the temperature of the sensor and/or the temperature of the reference product is caused to vary independently, light intensity measurements supplied by the sensor, the supply current setpoint values of the light source, the integration times of the sensor, and temperature measurements are collected, and a function supplying a corrected light intensity measurement corresponding to a reference temperature is determined, according to the measurements collected.

9. A spectrometer comprising a light source emitting a light beam, a sensor comprising light-sensitive cells disposed on a route of the light beam after it has interacted with a product to be analyzed, and a control device controlling a supply current of the light source, and an integration time of the light-sensitive cells,

wherein the control device is configured to implement the method according to claim 1.

10. Spectrometer according to claim 9, wherein the light source comprises several light-emitting diodes having different emission spectra to cover an analysis wavelength band, and a photodiode to measure the light intensity of the light beam emitted by the light-emitting diodes before the light beam interacts with the product to be analyzed.

11. Spectrometer according to claim 10, wherein the light source is configured to supply the control device with voltages and/or currents for supplying the light-emitting diodes.

12. Spectrometer according to claim 10, wherein the light-emitting diodes are integrated into a same electronic component.

13. Spectrometer according to claim 9, comprising a temperature sensor supplying measurements of the temperature of the light source, and/or a temperature sensor supplying measurements of the temperature of the sensor, and/or a temperature sensor supplying measurements of the temperature of the product to be analyzed.

14. Spectrometer according to claim 9, comprising a measurement cell in which a product to be analyzed interacts with the light beam, an optical collimating element to shape the beam at output of the light source and transmit it to the measurement cell, a wavelength filter configured to spatially spread the different wavelengths of the light beam at output of the measurement cell and transmit them to different light-sensitive cells of the sensor, the light source, the optical element, the measurement cell, the filter and the sensor being assembled so as not to form any air zone susceptible of being passed through by the light beam between the light source and the sensor.