GB2399178A - Method of accurately estimating air to fuel ratio - Google Patents
Method of accurately estimating air to fuel ratio Download PDFInfo
- Publication number
- GB2399178A GB2399178A GB0305115A GB0305115A GB2399178A GB 2399178 A GB2399178 A GB 2399178A GB 0305115 A GB0305115 A GB 0305115A GB 0305115 A GB0305115 A GB 0305115A GB 2399178 A GB2399178 A GB 2399178A
- Authority
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- United Kingdom
- Prior art keywords
- exhaust
- treatment device
- afr
- oxygen
- storage capacity
- Prior art date
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- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 18
- 239000000446 fuel Substances 0.000 title claims abstract description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 66
- 239000001301 oxygen Substances 0.000 claims abstract description 66
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 66
- 239000007789 gas Substances 0.000 claims abstract description 17
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 6
- 238000012935 Averaging Methods 0.000 claims description 4
- 239000000203 mixture Substances 0.000 description 19
- 239000003054 catalyst Substances 0.000 description 7
- 238000005259 measurement Methods 0.000 description 6
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 238000011144 upstream manufacturing Methods 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000779 depleting effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000003094 perturbing effect Effects 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000009738 saturating Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
- F02D41/1458—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio with determination means using an estimation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
- F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
- F02D41/1456—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio with sensor output signal being linear or quasi-linear with the concentration of oxygen
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
- F02D41/187—Circuit arrangements for generating control signals by measuring intake air flow using a hot wire flow sensor
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
A method is disclosed for accurately estimating the air to fuel ratio (AFR) in the feedgas supplied by an engine 10 to an exhaust after-treatment device 20. The method comprises the steps of: <SL> <LI>a) measuring the mass flow rate through the exhaust after-treatment device 20, <LI>b) providing an oxygen sensor 30 downstream of the exhaust after-treatment device 20, <LI>c) operating the engine 10 with an estimated average value of AFR for a sufficient length of time to cause the exhaust after-treatment device 20 to change between an oxygen saturated state and an oxygen depleted state as detected by the downstream oxygen sensor 30, and <LI>d) determining an improved estimation of the AFR of the feed-gas supplied to the exhaust after-treatment device 20 from an estimated or otherwise measured or calculated value of the oxygen storage capacity of the exhaust after-treatment device 20 and the time integral of the measured mass flow rate over the duration of an interval between consecutive changes in state of the exhaust after-treatment device 20. </SL>
Description
METHOD OF ACCURATELY ESTIMATING AIR TO Curl RATIO The present invention
relates to a method of accurately estimating the air to fuel ratio (AFR) in the feedgas supplied by an engine to an oxygen storing exhaust aftertreatment device, such as a catalytic converter or a NOX trap. The measurement used herein for AFR will be AFR normalised with stoichiometric AFR, usually termed X, which has no units and value of 1 at stoichiometry.
Precise control of AFR bias is essential for minimising emissions on current technology exhaust after-treatment devices. Very small differences in bias (perhaps as little as 0.0017) can have a significant effect on tailpipe emissions.
Control of the air-to-fuel ratio (AFR) of the exhaust gases leaving the engine and entering the exhaust system, normally termed the feed-gas, is typically effected using a two-state exhaust gas oxygen (EGO) sensor mounted in the exhaust manifold upstream of the after treatment device to indicate whether the feed-gas AFR is rich (<1) or lean (>1) of stoichiometry. When the feed-gas AFR is lean more fuel is supplied to the engine and when it is rich less fuel is supplied to the engine so that the output signal of the EGO sensor constantly switches between the two states. The asymmetry of the fuelling supply waveform produced using this technique can be adjusted to achieve a desired variation from stoichiometry, termed the bias. As the only exhaust gas AFR reference is the EGO sensor switch point, control of the bias is essentially feedforward. The closed loop bias is calibrated to achieve a trade off between HO, CO and NOX emissions at a given engine speed and load.
Due to the sensitivity of emissions to bias and the susceptibility of the EGO sensor to errors due to sensor deterioration with age and poor cylinder-to-cylinder mixture distribution across the sensor, a feedback control system - 2 - has been in use for some time which employs an additional HEGO sensor positioned downstream of the after-treatment device. A known system, known by the acronym FAOSC (Fore-Aft Oxygen Sensor Control), trims the bias based on the output of this downstream sensor. As the sensor has a limited range of useful operation (the gain drops off sharply away from stoichiometry), the range of bias that can be usefully controlled is limited. Additionally the sensor characteristics are less predictable away from the switch point, because of variation between sensors and the influence of changes in temperature, resulting in a range of sensor output at a given AFR. This further limits the range of biases that can be reliably controlled when using the FAOSC system.
It has been found when optimising engine calibration to minimise emissions using current technology catalysts and NOX traps that it is necessary to set the bias with an accuracy outside the reliable range of the current FAOSC system.
In addition to these robustness issues, further tightening of emissions standards and greater emphasis on optimal use of catalyst volume may require the use of a strategy based on a real-time oxygen storage model. This would ideally include assessment of total oxygen storage capacity as well as an instantaneous estimation of stored oxygen. For any estimation of currently stored oxygen, the oxygen/reductant flow rate into the catalyst must be known with a high degree of accuracy. Small errors in the AFR estimation would affect the calculation of stored oxygen level in the oxygen storage model. The current downstream sensor signal could be utilised providing the AFR associated with a given sensor output could be accurately predicted. This however is limited in its useful range, for the reasons discussed earlier. - 3 -
An alternative method of determining feed-gas AFR, which would satisfy the requirements of the FAOSC system and the oxygen storage model, would be to measure how long it takes for an exhaust after-treatment device of known oxygen capacity to go from fully saturated with oxygen to fully depleted or vice versa as sensed by the downstream HEGO sensor. This however requires a knowledge of the oxygen storage capacity of the exhaust after-treatment device, which itself is not constant.
According to a first aspect of the invention, there is provided a method of accurately estimating the air to fuel ratio (AFR) in the feedgas supplied by an engine to an exhaust after-treatment device, comprising the steps of: a) measuring the mass flow rate through the exhaust after treatment device, b) providing an oxygen sensor downstream of the exhaust after-treatment device, c) operating the engine with an estimated average value of AFR for a sufficient length of time to cause the exhaust aftertreatment device to change between an oxygen saturated state and an oxygen depleted state as detected by the downstream oxygen sensor, and d) determining an improved estimation of the AFR of the feed-gas supplied to the exhaust after-treatment device from an estimated or otherwise measured or calculated value of the oxygen storage capacity of the exhaust after-treatment device and the time integral of the measured mass flow rate over the duration of an interval between consecutive changes in state of the exhaust after-treatment device.
In step c), the engine can be operated with a fixed AFR but it may alternatively be switched alternately between rich and lean settings to achieve an estimated average AFR value or bias. À 4
The Applicants have earlier proposed in EP 1177371 perturbing the closed loop AFR bias between slightly rich and slightly lean in order to expose more of the catalyst to both rich and lean AFR - essentially exercising the catalyst in order to remove poison(s). The present invention can be used in conjunction with such a method of prolonging the life of a exhaust after-treatment device to arrive at a more accurate measure of the AFR.
lo Following steps a), b) and c), the method may comprise the further steps of: cl) deriving an estimate of the oxygen storage capacity of the exhaust after-treatment device from the estimated value of AFR and the integral of the measured mass flow rate over the time taken by the exhaust after-treatment device to change between the two states, c2) repeating steps c) and cl) with different estimated average values of AFR to derive different estimates of the oxygen storage capacity, and c3) averaging the different estimates of the oxygen storage capacity to arrive at a truer value of the storage capacity of the exhaust after- treatment device, Wherein the truer value of the oxygen storage capacity of the exhaust after-treatment device derived from step c3) is used in step d) to determine the improved estimation of the AFR of the feed-gas supplied to the exhaust after-treatment device.
If in steps c) and cl), the engine is operated in a rich mode, then the oxygen storage capacity can be estimated from the time it takes for the exhaust after-treatment device to be fully depleted of oxygen (reductant break through to the downstream sensor) after a period in which the exhaust after-treatment device has been fully saturated with oxygen.
If, on the other hand, the engine is operated in a lean mode, then it is the total mass flow required to fully saturate the exhaust aftertreatment device after a period - 5 of reductant break through to the downstream sensor that needs to be measured. t The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of an engine with its intake and exhaust systems) Figure 2 shows the output waveform of the upstream exhaust lo gas oxygen sensor in the engine of Figure 1; and Figure 3 shows the output waveform of the downstream exhaust gas oxygen sensor drawn to a different time scale.
In Figure 1, there is schematically represented an engine 10 having an intake system 12 and an exhaust system 14. Within the intake system, intake air flows through a meter 16 which measures the mass air flow and a throttle 18 which sets the engine load. Fuel is added to the intake air by means of injectors 22 controlled by a fuel system 24.
In the exhaust system 14, the exhaust gases from the engine pass through a exhaust after-treatment device 20, which may I for example be a three- way catalyst, before being discharged to atmosphere. Exhaust gas oxygen sensors 28 and 30 are located respectively upstream and downstream of the exhaust after-treatment device 20.
An electronic engine control unit 26 receives signals from the engine 10, the mass air flow meter 16 and two EGO sensors 28 and 30, as well as signals indicative of other engine operating parameters such as load and temperature. I Based on these signals the control unit determines the quantity of fuel supplied to the engine through the injectors 22 from the fuel system.
To set a mixture strength that is near stoichiometric, it is possible to rely on the output of the EGO sensor 28. If - 6 oxygen is sensed by the sensor 28, then the mixture is immediately made richer and conversely if no oxygen is sensed by the sensor 28 then the mixture is made leaner. The net result is that the mixture strength will then oscillate as illustrated by each of the sections A, B and C of the waveform shown in Figure 1. The value of the mixture strength will approximate to stoichiometry but will differ from stoichiometry by an amount that is referred to herein as the bias. As is shown in Figure 2, the bias is determined lo by the asymmetry of the waveform being dependent upon the relative amplitude and duration of the rich and lean excursions. In the case of sections A and C, the mixture has a rich bias MA and ic whereas in section B the mixture has a lean bias JOB. Stoichiometry is defined as having the value :5 = 1 and if the ratio measured is air to fuel (AFR) then a lean mixture with excess air will have a value of > 1 and a rich mixture a value of < 1.
It is desirable to know the bias with a high degree of accuracy and this has hitherto been difficult to establish because such parameters as the switching point of the exhaust gas oxygen sensor 28 will vary with age and from one sensor to another.
2s It would be possible to assess the value of the bias if one could determine with accuracy the oxygen storage capacity of the exhaust aftertreatment device 20. It is well known that three way catalysts (and NOX traps) store oxygen during lean periods and that this stored oxygen is used to react with surplus reductant (predominantly carbon monoxide and hydrocarbons but possible also hydrogen) in the feedgas during rich periods. If one starts by running the engine with a constantly rich mixture or with a mixture having a rich bias, a point will be reached when all the oxygen previously stored in the exhaust after-treatment device has been depleted, whereupon reductant will break through the exhaust after-treatment device 20 and will be detected by - 7 - the downstream sensor 30. If at this point the mixture is immediately switched to a lean mixture, the exhaust after- treatment device 20 will slowly fill up with oxygen once again until the point is reached when oxygen breaks through the exhaust after-treatment device and is detected by the downstream sensor 30. If the oxygen storage capacity of the exhaust after-treatment device is known, then the AFR of the mixture or the bias can be determined from the total mass air flow during the period between the two switching states lo of the downstream sensor 30.
In accordance with the present invention, the storage capacity of the exhaust after-treatment device may be estimated or otherwise measured or calculated.
Unfortunately, the storage capacity of the exhaust after- treatment device may not be accurately known because it too varies with temperature and from one exhaust after-treatment device to another. It is also affected by ageing of the exhaust after-treatment device.
In the present invention, this problem may be overcome by obtaining several estimates of the storage capacity of the exhaust after-treatment device based on different assumed values of AFR or bias and these estimates are averaged to arrive at a truer value. After arriving at a truer value of the storage capacity, this value can be to correct errors in the assumed values of the AFR or bias, and thereby to calibrate the AFR or bias.
The flow rate of oxygen into the exhaust after-treatment device when running with mixture have an assumed constant or mean value of AFR equal to HA iS given by the equation: (AM _ tAM i: 23.2 Eq. 1 where AM is the measured mass air flow rate and 23.2 is the percentage of oxygen in air by weight. - 8
If it takes from time Tl to time T2 for the exhaust after- treatment device to go from full depletion to saturation (as indicated by a change in the output signal of the sensor 30 illustrated in Figure 3), then a first estimate of the oxygen storage capacity of the exhaust aftertreatment device is given by the equation: CaPacityA= (AM ( JA j) 1OO Eq. 2 The process of fully saturating the exhaust after-treatment device with oxygen, or fully depleting it, is repeated with different values of X, to arrive at different estimates of the oxygen storage capacity of the exhaust after-treatment device. A truer estimate of the capacity, CapacityReal, is then obtained by averaging the individual estimates.
CapacityReal = 1/n(CapacityA + CapacityB CapacityN) Once CapacityReal has been evaluated, then its value can be substituted for CapacityA in Equation 2 to arrive at a more accurate value of A In order to arrive at a truer estimate of the oxygen storage capacity, it is possible to use one value of that is richer than stoichiometry and another that is leaner. In this case, one integrates over two periods, one to saturate the exhaust after-treatment device with oxygen and the other to deplete it fully.
It is not however essential to use values of on opposite sides of stoichiometry, and one can arrive at different estimates of the storage capacity based on values of that are all rich or all lean provided that the after-treatment device changes from a saturated to a depleted state, or vice versa. - 9
It would naturally be obtrusive to switch the engine to a lean setting for a prolonged period and then to a lean setting for a prolonged period purely for the purpose of calibrating the assumed values of AFR. This however is not necessary as the measurement of the oxygen storage capacity need only be done infrequently. It is therefore possible for the oxygen storage capacity to be carried out as and when the correct conditions arise naturally. For example when driving up a long hill, the engine may naturally operate lo under high load conditions for a sufficient length of time to deplete the oxygen stored in the exhaust after-treatment device. Conversely when driving down a long hill, the engine will operate with a weak mixture for long enough to saturate the exhaust after-treatment device with oxygen.
Furthermore, a relatively small degree of bias is sufficient to enable the oxygen storage capacity to be evaluated and the effect of changing mixture strength need not be so great as to affect the engine performance significantly. It is of course also possible to vary the spark timing in conjunction with the changes in the setting of the mixture strength to avoid changes in engine output power.
It has been previously proposed by the Applicants, to run alternately with rich and lean values of bias in order to prevent degradation of the exhaust after-treatment device - and the present invention can take advantage of such cycling of the bias in order to correct fuelling errors.
A truer value of storage capacity can be arrived at by averaging only two measurements but iteration of the - procedure will cause ever more accurate calibration. It is therefore possible to form a rolling average of several measurements and to apply weighting factors to attach greater importance to more recent measurements. -
It is an advantage of the invention that the measurement of the oxygen storage capacity of the exhaust after-treatment device is itself a useful parameter indicative of its condition and it is desirable to issue a warning when the evaluated capacity of exhaust after-treatment device drops below a threshold value. Such a warning signal may be used to initiate desulphation or to warn that the converter is in need of replacement.
Claims (5)
1. A method of accurately estimating the air to fuel ratio (AFR) in the feedgas supplied by an engine to an exhaust after-treatment device, comprising the steps of: a) measuring the mass flow rate through the exhaust after treatment device, b) providing an oxygen sensor downstream of the exhaust after-treatment device, lo c) operating the engine with an estimated average value of AFR for a sufficient length of time to: cause the exhaust after-treatment device to change between an oxygen saturated state and an oxygen depleted state as detected by the downstream oxygen sensor, and d) determining an improved estimation of the AFR of the feed-gas supplied to the exhaust after-treatment device from an estimated or otherwise measured or calculated value of the oxygen storage capacity of the exhaust after-treatment device and the time integral of the measured mass flow rate over the duration of an interval between consecutive changes in state of the exhaust after-treatment device.
2. A method as claimed in claim 1, wherein, in step c), the engine is operated with a fixed AFR.
3. A method as claimed in claim 1, wherein, in step c), the engine is switched alternately between rich and lean settings to achieve an estimated average bias.
4. A method as claimed in any preceding claim, wherein, following steps a) , b) and c), the method comprises the further steps of: cl) deriving an estimate of the oxygen storage capacity of the exhaust after-treatment device from the estimated value of AFR and the integral of the measured mass flow rate over the time taken by the exhaust after-treatment device to change between the two states, - 12 c2) repeating steps c) and cl) with different estimated average values of AFR to derive different estimates of the oxygen storage capacity, and c3) averaging the different estimates of the oxygen storage capacity to arrive at a truer value of the storage capacity of the exhaust after-treatment device, Wherein the truer value of the oxygen storage capacity of the exhaust after-treatment device derived from step c3) is used in step d) to determine the improved estimation of the lo AFR of the feed-gas supplied to the exhaust after- treatment device.
5. A method as claimed in claim 4, wherein a warning signal is generated when the truer value of the storage capacity drops below a preset threshold.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0305115A GB2399178B (en) | 2003-03-06 | 2003-03-06 | Method of accurately estimating air to fuel ratio |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0305115A GB2399178B (en) | 2003-03-06 | 2003-03-06 | Method of accurately estimating air to fuel ratio |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0305115D0 GB0305115D0 (en) | 2003-04-09 |
| GB2399178A true GB2399178A (en) | 2004-09-08 |
| GB2399178B GB2399178B (en) | 2006-06-07 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0305115A Expired - Fee Related GB2399178B (en) | 2003-03-06 | 2003-03-06 | Method of accurately estimating air to fuel ratio |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2399178B (en) |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4211116A1 (en) * | 1992-04-03 | 1993-10-07 | Bosch Gmbh Robert | On-board detection of state of IC engine exhaust catalyser - increasing lean-rich cycle until exhaust gas probe signal indicates noticeable change to determine oxygen@ storage capacity |
| US5901552A (en) * | 1996-02-23 | 1999-05-11 | Robert Bosch Gmbh | Method of adjusting the air/fuel ratio for an internal combustion engine having a catalytic converter |
| US6076348A (en) * | 1998-06-26 | 2000-06-20 | Ford Motor Company | Engine operating system for maximizing efficiency and monitoring performance of an automotive exhaust emission control system |
| JP2000303880A (en) * | 1999-04-26 | 2000-10-31 | Unisia Jecs Corp | Oxygen storage quantity control device for catalytic converter rhodium |
| WO2000068551A1 (en) * | 1999-05-05 | 2000-11-16 | Ford Global Technologies, Inc. | Engine management system |
| EP1128046A2 (en) * | 2000-02-24 | 2001-08-29 | Nissan Motor Co., Ltd. | Engine exhaust purification device |
| EP1128043A2 (en) * | 2000-02-23 | 2001-08-29 | Nissan Motor Co., Ltd. | Air-fuel ratio control of engine |
| EP1130239A2 (en) * | 2000-02-17 | 2001-09-05 | Nissan Motor Co., Ltd. | Engine exhaust purification device |
| EP1167726A2 (en) * | 2000-06-26 | 2002-01-02 | Toyota Jidosha Kabushiki Kaisha | Air-fuel ratio control apparatus of internal combustion engine |
| US20020152743A1 (en) * | 2000-02-16 | 2002-10-24 | Takeshi Nakamura | Engine exhaust purification device |
| US20020157381A1 (en) * | 2000-02-25 | 2002-10-31 | Masatomo Kakuyama | Engine exhaust purification arrangement |
| US20020157380A1 (en) * | 2000-02-24 | 2002-10-31 | Masatomo Kakuyama | Engine exhaust purification device |
-
2003
- 2003-03-06 GB GB0305115A patent/GB2399178B/en not_active Expired - Fee Related
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4211116A1 (en) * | 1992-04-03 | 1993-10-07 | Bosch Gmbh Robert | On-board detection of state of IC engine exhaust catalyser - increasing lean-rich cycle until exhaust gas probe signal indicates noticeable change to determine oxygen@ storage capacity |
| US5901552A (en) * | 1996-02-23 | 1999-05-11 | Robert Bosch Gmbh | Method of adjusting the air/fuel ratio for an internal combustion engine having a catalytic converter |
| US6076348A (en) * | 1998-06-26 | 2000-06-20 | Ford Motor Company | Engine operating system for maximizing efficiency and monitoring performance of an automotive exhaust emission control system |
| JP2000303880A (en) * | 1999-04-26 | 2000-10-31 | Unisia Jecs Corp | Oxygen storage quantity control device for catalytic converter rhodium |
| WO2000068551A1 (en) * | 1999-05-05 | 2000-11-16 | Ford Global Technologies, Inc. | Engine management system |
| US20020152743A1 (en) * | 2000-02-16 | 2002-10-24 | Takeshi Nakamura | Engine exhaust purification device |
| EP1130239A2 (en) * | 2000-02-17 | 2001-09-05 | Nissan Motor Co., Ltd. | Engine exhaust purification device |
| EP1128043A2 (en) * | 2000-02-23 | 2001-08-29 | Nissan Motor Co., Ltd. | Air-fuel ratio control of engine |
| EP1128046A2 (en) * | 2000-02-24 | 2001-08-29 | Nissan Motor Co., Ltd. | Engine exhaust purification device |
| US20020157380A1 (en) * | 2000-02-24 | 2002-10-31 | Masatomo Kakuyama | Engine exhaust purification device |
| US20020157381A1 (en) * | 2000-02-25 | 2002-10-31 | Masatomo Kakuyama | Engine exhaust purification arrangement |
| EP1167726A2 (en) * | 2000-06-26 | 2002-01-02 | Toyota Jidosha Kabushiki Kaisha | Air-fuel ratio control apparatus of internal combustion engine |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0305115D0 (en) | 2003-04-09 |
| GB2399178B (en) | 2006-06-07 |
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