Apparatus and method for diagnosis of catalyst performance
First Claim
1. A method comprising the steps of:
- passing a stream of fluid containing at least one fluctuating parameter through a unit operation comprising at least one of a catalyst, a reactor and an absorber, said unit operation affecting the one fluctuating parameter;
sensing, downstream of said unit operation, at least one parameter value as a function of time of said at least one fluctuating parameter having a frequency in the fluid stream;
determining at least one frequency parameter as a function of said at least one parameter value and the frequency, and a first control value based on said frequency parameter;
determining a second control value correlated to the frequency of said fluctuating parameter independently of said first control value; and
generating a control signal based on a comparison of the first and second control values.
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Accused Products
Abstract
A method and apparatus that converts time-resolved sensor signals into frequency domain signals using Fast Fourier Transforms and power spectral densities. A signal, as a means to assess catalyst performance such as a signal based on sensing oxygen concentration in motor vehicle exhaust in accordance with the present invention is in the time domain and has multiple components at different frequencies. The use of Fast Fourier Transforms isolates the various spectral density which arise from different frequency components of the complex time domain signal. The analysis has been found to be substantially independent of operating conditions. The power spectral density has found to be a precise indication of oxygen storage and release of the catalyst and catalyst performance. The catalyst performance can be signaled to the vehicle operator for on board diagnostics (OBD) of the catalyst.
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Citations
52 Claims
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1. A method comprising the steps of:
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passing a stream of fluid containing at least one fluctuating parameter through a unit operation comprising at least one of a catalyst, a reactor and an absorber, said unit operation affecting the one fluctuating parameter; sensing, downstream of said unit operation, at least one parameter value as a function of time of said at least one fluctuating parameter having a frequency in the fluid stream; determining at least one frequency parameter as a function of said at least one parameter value and the frequency, and a first control value based on said frequency parameter; determining a second control value correlated to the frequency of said fluctuating parameter independently of said first control value; and generating a control signal based on a comparison of the first and second control values. - View Dependent Claims (2, 3, 4)
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5. A method comprising the steps of:
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sensing a parameter value as a function of time of a fluctuating parameter having a frequency in a gaseous stream; determining a cumulative spectral density for a frequency range, and a control value based on the frequency parameter; comparing the cumulative spectral density to a preset value to obtain a control value; and generating a control signal based on the control value, wherein the gaseous stream is a stream comprising hydrocarbons and oxygen and the fluctuating parameter is the concentration of oxygen. - View Dependent Claims (6)
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7. A method comprising the steps of:
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sensing an upstream parameter value as a function of time of an upstream fluctuating parameter having an upstream frequency in a gaseous stream upstream of a unit operation; determining an upstream cumulative spectral density of the upstream fluctuating parameter for an upstream frequency range, and an upstream control value based on the upstream cumulative parameter value; generating an upstream control signal based on the upstream control value; sensing the downstream parameter value as a function of time of a downstream fluctuating parameter having a downstream frequency in the gaseous stream downstream of a unit operation; determining a downstream cumulative spectral density for a downstream frequency range, and a downstream control value based on the downstream cumulative spectral density; generating a downstream control signal based on the downstream control value; and adjusting the downstream control signal as a function of the upstream control signal, wherein the gaseous stream is a stream comprising hydrocarbons and oxygen and the upstream fluctuating parameter is the concentration of oxygen at an upstream location and the downstream fluctuating parameter is the concentration of oxygen at a downstream location downstream of the upstream location. - View Dependent Claims (8, 9)
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10. A method comprising the steps of:
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sensing a downstream gas component, selected from oxygen and hydrocarbon concentration as a function of time and said gas component concentration having a downstream frequency in a gaseous exhaust stream, comprising hydrocarbons and oxygen, in an exhaust conduit downstream of a hydrocarbon oxidation catalyst located in the exhaust conduit; determining a downstream frequency parameter as a function of anyone of the downstream oxygen and hydrocarbon concentration and downstream frequency; comparing the downstream frequency parameter to an downstream preset value to obtain an downstream control value; generating a downstream control signal based on the downstream control value; assessing the performance of the hydrocarbon oxidation catalyst as a function of the downstream control signal; and signaling, with the control signal, the performance of the hydrocarbon oxidation catalyst. - View Dependent Claims (11, 12, 17, 18)
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13. A method comprising the steps of:
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sensing an upstream gas component, selected from oxygen and hydrocarbon concentration, as a function of time and said gas component concentration, the gas component concentration having an upstream frequency in a gaseous exhaust stream comprising hydrocarbons and oxygen, in an exhaust conduit upstream of a hydrocarbon oxidation catalyst located in the exhaust conduit; determining an upstream frequency parameter as a function of anyone of the upstream oxygen and hydrocarbon concentration and upstream frequency, and an upstream control value based on the upstream frequency parameter; generating an upstream control signal based on the upstream control value; sensing a downstream gas component, selected from oxygen and hydrocarbon concentration as a function of time and said gas component concentration having a downstream frequency in the gaseous exhaust stream, in the exhaust conduit downstream of the hydrocarbon oxidation catalyst; determining a downstream frequency parameter as a function of anyone of the downstream oxygen and hydrocarbon concentration and downstream frequency, and a downstream control value based on the downstream frequency parameter; generating a downstream control signal based on the downstream control value; adjusting the downstream control signal as a function of the upstream control signal; assessing the performance of the hydrocarbon oxidation catalyst as a function of the adjusted downstream control signal; and signaling the performance of the hydrocarbon oxidation catalyst. - View Dependent Claims (14, 15, 16)
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19. An apparatus comprising:
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a conduit; a unit operation in communication with the conduit; a sensor located downstream of the unit operation, the sensor comprising a means to measure a downstream parameter value as a function of time of a fluctuating downstream parameter having a downstream frequency in a gaseous or liquid stream; means to determine a frequency parameter as a function of the downstream parameter value and downstream frequency; means to compare the downstream frequency parameter to a preset downstream frequency parameter value to obtain a downstream control value; and means to generate a downstream control signal based on the downstream control value wherein the unit operation is selected from the group of a catalyst, reactor and adsorber.
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20. An apparatus comprising:
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a conduit; a catalyst in communication with the conduit; an upstream sensor located upstream of the catalyst, the upstream sensor comprising a means to measure an upstream parameter value as a function of time of a fluctuating upstream parameter having an upstream frequency in anyone of a gaseous and liquid stream; means to determine an upstream frequency parameter as a function of the upstream parameter value and upstream frequency, and an upstream control value; means to generate an upstream control signal based on an upstream control value; a downstream sensor located downstream of the catalyst, the downstream sensor comprising a means to measure a downstream parameter value as a function of time of a fluctuating downstream parameter having a downstream frequency in a anyone of gaseous and liquid stream; means to determine a downstream frequency parameter as a function of the downstream parameter value and frequency, and a downstream control value, based on the downstream frequency parameter; means to generate a downstream control signal based on a downstream control value; and means to adjust the downstream control signal as a function of the upstream control signal. - View Dependent Claims (21, 22, 23, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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24. An apparatus comprising:
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a conduit; a hydrocarbon oxidation catalyst located in the conduit catalyst; an upstream sensor selected from an oxygen sensor and a hydrocarbon sensor located in communication with the conduit upstream of the catalyst, the upstream sensor comprising means to sense upstream gas component, selected from oxygen and hydrocarbon concentration as a function of time and said gas component having an upstream frequency, in the exhaust conduit upstream of the upstream of the hydrocarbon oxidation catalyst; means to determine an upstream frequency parameter as a function of the upstream gas component concentration and upstream frequency, and an upstream control value, based on the upstream frequency parameter value; means to generate an upstream control signal based on an upstream control value; a downstream sensor selected from an oxygen sensor and a hydrocarbon sensor located downstream of the catalyst, the downstream sensor comprising means to sense a downstream gas component, selected from oxygen and hydrocarbon concentration as a function of time and said gas component having a downstream frequency, in the exhaust conduit downstream of the hydrocarbon oxidation catalyst; means to determine a downstream frequency parameter as a function of the downstream gas component concentration and downstream frequency, and a control value based on the downstream frequency parameter value; means to generate a downstream control signal based on a downstream control value; means to adjust the downstream control signal as a function of the upstream control signal; means to assess the performance of the hydrocarbon oxidation catalyst as a function of the adjusted downstream control signal and generate a performance signal; and an indicator to indicate catalyst performance. - View Dependent Claims (25, 26, 27)
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39. An apparatus comprising:
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a conduit; a unit operation in communication with the conduit, the unit operation including a catalyst which comprises at least one catalytic component and at least one oxygen storage component; a sensor located downstream of the unit operation, the sensor comprising a means to measure a downstream parameter value as a function of time of a fluctuating downstream parameter having a downstream frequency in a gaseous or liquid stream; means to determine a frequency parameter as a function of the downstream parameter value and downstream frequency; means to compare the downstream frequency parameter to a preset downstream frequency parameter value to obtain a downstream control value; and means to generate a downstream control signal based on the downstream control value. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46)
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47. An apparatus comprising:
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a conduit; a unit operation in communication with the conduit; a sensor located downstream of the unit operation, the sensor comprising a means to measure a downstream parameter value as a function of time of a fluctuating downstream parameter having a downstream frequency in a gaseous or liquid stream; means to determine a frequency parameter as a function of the downstream parameter value and downstream frequency; means to compare the downstream frequency parameter to a preset downstream frequency parameter value to obtain a downstream control value; means to generate a downstream control signal based on the downstream control value; and means to determine the frequency parameter over a range of from 0 to 1.5. - View Dependent Claims (48)
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49. A method for controlling at least one of and monitoring a function of a vehicle having an internal combustion engine by sensing a fluctuating parameter of a fluid in a conduit affecting the operation of the engine, said method comprising the steps of:
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a) providing a unit operation which affects the fluctuating parameter of the fluid; b) passing the fluid in the conduit through the unit operation; c) providing a downstream sensor sensing the fluctuation parameter downstream of the unit operation; d) obtaining a plurality of time history signals from the downstream sensor; e) converting each time history sensor signal in the time domain to a plurality of frequency signals in the frequency domain for a set frequency range; f) summing the signal output for all the frequency signals in the set frequency range for a plurality of sensor signals to generate a first control value; g) computing a control signal for use by the vehicle based on the relationship of the first control value relative to a second control value correlated to the first control value. - View Dependent Claims (50, 51, 52)
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Specification