CA1174334A - Statistical air fuel ratio control - Google Patents
Statistical air fuel ratio controlInfo
- Publication number
- CA1174334A CA1174334A CA000376948A CA376948A CA1174334A CA 1174334 A CA1174334 A CA 1174334A CA 000376948 A CA000376948 A CA 000376948A CA 376948 A CA376948 A CA 376948A CA 1174334 A CA1174334 A CA 1174334A
- Authority
- CA
- Canada
- Prior art keywords
- fuel ratio
- air fuel
- engine
- rich
- lean
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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
- F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
- F02D41/26—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor
- F02D41/263—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor the program execution being modifiable by physical parameters
-
- 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
- F02D41/1477—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation circuit or part of it,(e.g. comparator, PI regulator, output)
- F02D41/1481—Using a delaying circuit
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
ABSTRACT
This specification discloses an apparatus and method for controlling the air fuel ratio in an internal combustion engine in response to a feedback signal from an exhaust gas oxygen sensor. The sensor output signal is sampled periodically. After a given number of samples, a decision is made to change the air fuel ratio in either a rich or lean direction or to leave the fuel metering unchanged. Biasing, or non-stoichiometric air fuel operation, can be achieved by logic requiring a pre-determined number of samples to be either lean or rich.
This specification discloses an apparatus and method for controlling the air fuel ratio in an internal combustion engine in response to a feedback signal from an exhaust gas oxygen sensor. The sensor output signal is sampled periodically. After a given number of samples, a decision is made to change the air fuel ratio in either a rich or lean direction or to leave the fuel metering unchanged. Biasing, or non-stoichiometric air fuel operation, can be achieved by logic requiring a pre-determined number of samples to be either lean or rich.
Description
33~
- STATISTICAL AIR FUEL RATIO CONTROL
This invention relates to engine fuel control systems which incorporate an air/fuel ratio feedback control.
Various fuel control systems are known in the prior art in which the quantity of fuel fed to the engine is controlled by sensors in the exhaust gas which give an indication of the air fuel ratio. Nevertheless, it remains extremely di~ficult to compensate for the ever changing operating conditions of the engine, the varia-tions among different engines and so on as to alwaysoperate the engine with a predetermined air fuel ratio.
This drawback may become critical when the engine is equipped with a catalytic converter for reducing un~esirable components of the exhaust gases.
A widely used technique to control the air fuel ratio in stoichiometric feedback controlled fuel metering systems is limit cycle integral control. In this technique, there is a constant movement of a fuel metering camponent in a direction that always tends to counter the instantaneous air fuel ratio indication given by a typical two state exhaust gas oxygen (EG0) sensor. For example, every time an EG0 sensor indicates a switch from a rich to a lean air fuel ratio mode of operation, the direction of motion of a typical carburetor's metering rod reverses to create a richer air fuel ratio condition until the sensor indicates a change from a lean to rich air fuel ratio condition. Then, the direction of motion of the metering rod is reversed again this time to achieve a leaner air fuel ratio condition.
Referring to Figs. la and lb, step like changes in the sensor output voltage initiate ramp like changes in the actuator control voltage. When using the limit cycle integral control, the desired air fuel ratio can only be attained on an average basis since the actual air fuel ratio is made to fluctuate in a controlled manner about the average value. The limit cycle integral control system can be characterized as a two state controller with the mode of operation being either rich ~ 3 ~
or lean. The average deviation from the desired value is a strong function of a parameter called engine transport delay time, tau. This is defined as the time it takes for a change in air fuel ratio, implemented at the fuel metering mechanism, to be recognized at the EGO sensor, after the change has taken place.
The engine transport delay time is a function of the fuel metering system's design, engine speed, air flow, and EGO sensor characteristics. Because of this delay time, a control system using a limit cycle technique always varies the air fuel ratio about a mean value in a cyclical manner, a rich aix fuel ratio time regime typically followed by a lean air fuel ratio time regime. The shorter the transport delay time is, the higher will be the frequency of rich to lean and lean to rich air fuel ratio fluctuation and the smaller will be the amplitudes of the air fuel ratio overshoots. It can be appreciated that a system with no engine transport delay time is the ideal. These are some of the problems ~his invention overcomes.
This inve~tion recoynizes that the use of a three state controller can Lmprove the operation of a feedback controlled fuel flow system in an internal combustion ~ngine. The ~ontrol in a three state system has the ability to go rich or to go lean, and in addition, a third stat~ of operation is possible, a do nothing state.
In- accordance with the present invention, there is provided an air fuel ratio feedback type fuel supply system for an internal combustion engine comprising: sensing means for sensing the quantity of oxygen within the exhaust emission of the engine at a given repetition rate, the time interval between successive oxygen-sensing samples being at least as small as the time interval between succes-sive cylinder firings of the internal combustion engine;
control means coupled to receive the output of the sensing means for controlling the rate of supply of fuel to the engine as a function of the quantity of oxygen sensed by the sensing means, any change in the rate of supply ~1 ~ 3~
of fuel to the engine being accomplished by a step change, the size of the step being a function of a parameter descri-bing engine operationi and control means responding to the sampled output so that there are three decision states which act to make the air fuel ratio richer, make the air fuel ratio leaner and not alter the air fuel ratio, thereby reducing oscillation and magnitude of variations of the commanded air fuel ratios about the desired air fuel ratio, the control means determining that a stoichiometric air fuel ratio has been achieved and there is no need to alter the air fuel ratio command when sensing a rapid fluctuation in rich and lean stoichiometry indications due to cylinder to cylinder variation in air fuel ratio corresponding to a state of average cylinder stoichiometry.
The invention is described further, by way of illustration, with reference to the accompanying drawings, in which:
Fig. la is a graphical representation of the EGO sensor output voltage with respect to time in accordance with a prior art limit cycle controlled technique;
Fig. lb is a graphical representation of the actuator control voltage with respect to time correspond-ing to ths prior art sensor output vo'tage of Fig. la;
Pig. 2a is a sensor output voltage with respect to time in accordance with an embodiment of this invention;
Fig. 2b is a graph representation of an actuator control voltage with respect to time related to Fig. 2a and including an indication of the sampling times; and Fig. 3 is a block diagram of logic flow in accordance with an embodiment of this invention; and ~ ig. 4 is a partly schematic and partly block diagram of the connection of an engine fuel control 35 system which incorporates an air fuel ratio feedback control in accordance with an embodiment of this invention.
In accordance with an embodiment of this ~nvention, the EGO sensor signal is statistically sampled ~ 3'-~
and the fuel metering system is adjusted to produce the open loop-like stoichiometric air fuel ratio calibration. ~hus, this mode of operation is essentially totally independent of engine transport S delay time. Specifically, as shown in Figs. 2a and 2b, the EGO sensor signal could be sampled for rich and lean air fuel ratio indication every 30 milliseconds. Then after ten samples, taking 0.3 second to accumulate, a decision is made using the following criteria. If two or 1;0 less out of 10 indications were rich, the controller changes the air fuel ratio in the rich direction one step. If two or less out of ten indications were lean, the controller changes the air fuel ratio in the lean direction one step. If the lean or rich air fuel indications are between three and seven out of ten indications then nothing is done. This latter state would approximate the open loop calibration condition.
Such a decision pattern for three state control operation represents a stoichiometric air fuel ratio calibration.
If a nonstoichiometric air fuel ratio calibra-tion is desired, the condition for changing in the rich or lean air fuel ratio direction can be made asymmetrical.
That is, if two or less out of ten indications are rich, ma~e the controller change the air fuel ratio in the rich direction as before. In contrast, however, we can require that for a change in the lean direction four out of ten indications be required to be lean. Note that the frequency of EGO sensor fluctuations in Fig. 2a is much higher than the case in Fig. la due to the fact that the cylinder to cylinder fluctuations control the switching rather than the limit cycle mode of operation. In addition, a technique in accordance with an embodiment of this invention could show added benefit of operating engines at higher catalyst efficiencies by approximating a perfect open loop calibration more closely.
- 5 ~ 7~33~
Referring to Fig. 3, a logic control flow chart in accordance with an embodiment of this invention begins with a block 31 at which a sample of an output of an exhaust gas oxygen sensor is taken. A typical rate S at which these samples are taken is, for example, every 30 milliseconds. Of course, this rate may be varied depending upon the particular engine control strategy selected.
~ - - At block 32, the sample taken at block 31 is added to previous samplings thereby forming a chain or train of samples. At block 33, a decision is made as to whether or not there are enough samples in the train of samples to make a decision. For example, the decision level may be ten samples and, if ten samples have not been accumulated, the logic goes to bloc~ 34 to wait for the next exhaust gas oxygen sensor sample. On the other hand, if 10 samples have been accumulated, a calculation is made at block 35 to determine the number of rich ~amples versus lean samples. At block 36 a decision is made whether the fraction of rich to lean indications is in the range requiring action. If no action is required, the logic flows to block 37 and the procedure is to wait for the next set of exhaust gas oxygen sensor indications.
On the other hand, if action is re~uired, a decision is made at block 38. If the indication is too rich, such as, for example, there are more than 7 out of 10 samples indicating rich air fuel ratio condition, the process goes to block 39. At block 39 there is a calculation of the air fuel ratio step size. That the size of the change in the air fuel ratio if a change is indicated. The step size can be based on an engine parameter. Fox example, the engihe parameter may be the rate of change of manifold absolute pressure. After calculation of the air fuel ratio step size at block 39, 35 an implementation at block 41 changes the air fuel ratio in the lean direction. Returning to block 38, if the .
- 6 ~ 334 indication is more than 7 out of 10 samples indicates lean air fuel ratio condition, a calculation is done at block 40 to determine the air fuel ratio step size. ~s in the calculation at block 39, this calculation is s based upon an engine parameter such as the rate of change of manifold absolute pressure. After the calculation of the step size at block 40, there is an implementation of the step in the air fuel ratio so that the air fuel ratio is changed in the rich direction at block 42.
- -Referring to Fig. 4, in accordance with an embodiment of this invention, an engine 50 has fuel flow control sub-system 51 for physically controlling the amount of fuel flowing. An exhaust gas oxygen sensor 52, a manifold absolute pressure sensor 53, and a throttle position sensor 54 provide inputs to a micro-processor based controller 55 for determining the desired air fuel ratio for engine 50. The desired air fuel ratio is implemented by fuel flow control sub-system 51 in response to an output provided by controller 55.
Various modifications and variations will no doubt occur to those skilled in the art to which this invention pertains. For example, the particular number of samples or frequency o~ samples may be varied from ~hat disclosed herein. These and all other variations which basically rely on the teachings through which this disclosure has advanced the art are properly considered within the scope of this invention.
.
- STATISTICAL AIR FUEL RATIO CONTROL
This invention relates to engine fuel control systems which incorporate an air/fuel ratio feedback control.
Various fuel control systems are known in the prior art in which the quantity of fuel fed to the engine is controlled by sensors in the exhaust gas which give an indication of the air fuel ratio. Nevertheless, it remains extremely di~ficult to compensate for the ever changing operating conditions of the engine, the varia-tions among different engines and so on as to alwaysoperate the engine with a predetermined air fuel ratio.
This drawback may become critical when the engine is equipped with a catalytic converter for reducing un~esirable components of the exhaust gases.
A widely used technique to control the air fuel ratio in stoichiometric feedback controlled fuel metering systems is limit cycle integral control. In this technique, there is a constant movement of a fuel metering camponent in a direction that always tends to counter the instantaneous air fuel ratio indication given by a typical two state exhaust gas oxygen (EG0) sensor. For example, every time an EG0 sensor indicates a switch from a rich to a lean air fuel ratio mode of operation, the direction of motion of a typical carburetor's metering rod reverses to create a richer air fuel ratio condition until the sensor indicates a change from a lean to rich air fuel ratio condition. Then, the direction of motion of the metering rod is reversed again this time to achieve a leaner air fuel ratio condition.
Referring to Figs. la and lb, step like changes in the sensor output voltage initiate ramp like changes in the actuator control voltage. When using the limit cycle integral control, the desired air fuel ratio can only be attained on an average basis since the actual air fuel ratio is made to fluctuate in a controlled manner about the average value. The limit cycle integral control system can be characterized as a two state controller with the mode of operation being either rich ~ 3 ~
or lean. The average deviation from the desired value is a strong function of a parameter called engine transport delay time, tau. This is defined as the time it takes for a change in air fuel ratio, implemented at the fuel metering mechanism, to be recognized at the EGO sensor, after the change has taken place.
The engine transport delay time is a function of the fuel metering system's design, engine speed, air flow, and EGO sensor characteristics. Because of this delay time, a control system using a limit cycle technique always varies the air fuel ratio about a mean value in a cyclical manner, a rich aix fuel ratio time regime typically followed by a lean air fuel ratio time regime. The shorter the transport delay time is, the higher will be the frequency of rich to lean and lean to rich air fuel ratio fluctuation and the smaller will be the amplitudes of the air fuel ratio overshoots. It can be appreciated that a system with no engine transport delay time is the ideal. These are some of the problems ~his invention overcomes.
This inve~tion recoynizes that the use of a three state controller can Lmprove the operation of a feedback controlled fuel flow system in an internal combustion ~ngine. The ~ontrol in a three state system has the ability to go rich or to go lean, and in addition, a third stat~ of operation is possible, a do nothing state.
In- accordance with the present invention, there is provided an air fuel ratio feedback type fuel supply system for an internal combustion engine comprising: sensing means for sensing the quantity of oxygen within the exhaust emission of the engine at a given repetition rate, the time interval between successive oxygen-sensing samples being at least as small as the time interval between succes-sive cylinder firings of the internal combustion engine;
control means coupled to receive the output of the sensing means for controlling the rate of supply of fuel to the engine as a function of the quantity of oxygen sensed by the sensing means, any change in the rate of supply ~1 ~ 3~
of fuel to the engine being accomplished by a step change, the size of the step being a function of a parameter descri-bing engine operationi and control means responding to the sampled output so that there are three decision states which act to make the air fuel ratio richer, make the air fuel ratio leaner and not alter the air fuel ratio, thereby reducing oscillation and magnitude of variations of the commanded air fuel ratios about the desired air fuel ratio, the control means determining that a stoichiometric air fuel ratio has been achieved and there is no need to alter the air fuel ratio command when sensing a rapid fluctuation in rich and lean stoichiometry indications due to cylinder to cylinder variation in air fuel ratio corresponding to a state of average cylinder stoichiometry.
The invention is described further, by way of illustration, with reference to the accompanying drawings, in which:
Fig. la is a graphical representation of the EGO sensor output voltage with respect to time in accordance with a prior art limit cycle controlled technique;
Fig. lb is a graphical representation of the actuator control voltage with respect to time correspond-ing to ths prior art sensor output vo'tage of Fig. la;
Pig. 2a is a sensor output voltage with respect to time in accordance with an embodiment of this invention;
Fig. 2b is a graph representation of an actuator control voltage with respect to time related to Fig. 2a and including an indication of the sampling times; and Fig. 3 is a block diagram of logic flow in accordance with an embodiment of this invention; and ~ ig. 4 is a partly schematic and partly block diagram of the connection of an engine fuel control 35 system which incorporates an air fuel ratio feedback control in accordance with an embodiment of this invention.
In accordance with an embodiment of this ~nvention, the EGO sensor signal is statistically sampled ~ 3'-~
and the fuel metering system is adjusted to produce the open loop-like stoichiometric air fuel ratio calibration. ~hus, this mode of operation is essentially totally independent of engine transport S delay time. Specifically, as shown in Figs. 2a and 2b, the EGO sensor signal could be sampled for rich and lean air fuel ratio indication every 30 milliseconds. Then after ten samples, taking 0.3 second to accumulate, a decision is made using the following criteria. If two or 1;0 less out of 10 indications were rich, the controller changes the air fuel ratio in the rich direction one step. If two or less out of ten indications were lean, the controller changes the air fuel ratio in the lean direction one step. If the lean or rich air fuel indications are between three and seven out of ten indications then nothing is done. This latter state would approximate the open loop calibration condition.
Such a decision pattern for three state control operation represents a stoichiometric air fuel ratio calibration.
If a nonstoichiometric air fuel ratio calibra-tion is desired, the condition for changing in the rich or lean air fuel ratio direction can be made asymmetrical.
That is, if two or less out of ten indications are rich, ma~e the controller change the air fuel ratio in the rich direction as before. In contrast, however, we can require that for a change in the lean direction four out of ten indications be required to be lean. Note that the frequency of EGO sensor fluctuations in Fig. 2a is much higher than the case in Fig. la due to the fact that the cylinder to cylinder fluctuations control the switching rather than the limit cycle mode of operation. In addition, a technique in accordance with an embodiment of this invention could show added benefit of operating engines at higher catalyst efficiencies by approximating a perfect open loop calibration more closely.
- 5 ~ 7~33~
Referring to Fig. 3, a logic control flow chart in accordance with an embodiment of this invention begins with a block 31 at which a sample of an output of an exhaust gas oxygen sensor is taken. A typical rate S at which these samples are taken is, for example, every 30 milliseconds. Of course, this rate may be varied depending upon the particular engine control strategy selected.
~ - - At block 32, the sample taken at block 31 is added to previous samplings thereby forming a chain or train of samples. At block 33, a decision is made as to whether or not there are enough samples in the train of samples to make a decision. For example, the decision level may be ten samples and, if ten samples have not been accumulated, the logic goes to bloc~ 34 to wait for the next exhaust gas oxygen sensor sample. On the other hand, if 10 samples have been accumulated, a calculation is made at block 35 to determine the number of rich ~amples versus lean samples. At block 36 a decision is made whether the fraction of rich to lean indications is in the range requiring action. If no action is required, the logic flows to block 37 and the procedure is to wait for the next set of exhaust gas oxygen sensor indications.
On the other hand, if action is re~uired, a decision is made at block 38. If the indication is too rich, such as, for example, there are more than 7 out of 10 samples indicating rich air fuel ratio condition, the process goes to block 39. At block 39 there is a calculation of the air fuel ratio step size. That the size of the change in the air fuel ratio if a change is indicated. The step size can be based on an engine parameter. Fox example, the engihe parameter may be the rate of change of manifold absolute pressure. After calculation of the air fuel ratio step size at block 39, 35 an implementation at block 41 changes the air fuel ratio in the lean direction. Returning to block 38, if the .
- 6 ~ 334 indication is more than 7 out of 10 samples indicates lean air fuel ratio condition, a calculation is done at block 40 to determine the air fuel ratio step size. ~s in the calculation at block 39, this calculation is s based upon an engine parameter such as the rate of change of manifold absolute pressure. After the calculation of the step size at block 40, there is an implementation of the step in the air fuel ratio so that the air fuel ratio is changed in the rich direction at block 42.
- -Referring to Fig. 4, in accordance with an embodiment of this invention, an engine 50 has fuel flow control sub-system 51 for physically controlling the amount of fuel flowing. An exhaust gas oxygen sensor 52, a manifold absolute pressure sensor 53, and a throttle position sensor 54 provide inputs to a micro-processor based controller 55 for determining the desired air fuel ratio for engine 50. The desired air fuel ratio is implemented by fuel flow control sub-system 51 in response to an output provided by controller 55.
Various modifications and variations will no doubt occur to those skilled in the art to which this invention pertains. For example, the particular number of samples or frequency o~ samples may be varied from ~hat disclosed herein. These and all other variations which basically rely on the teachings through which this disclosure has advanced the art are properly considered within the scope of this invention.
.
Claims (7)
1. An air fuel ratio feedback type fuel supply system for an internal combustion engine comprising:
sensing means for sensing the quantity of oxygen within the exhaust emission of the engine at a given repetition rate, the time interval between successive oxygen-sensing samples being at least as small as the time interval between successive cylinder firings of said internal combustion engine;
control means coupled to receive the output of said sensing means for controlling the rate of supply of fuel to the engine as a function of the quantity of oxygen sensed by said sensing means, any change in the rate of supply of fuel to the engine being accomplished by a step change, the size of the step being a function of a parameter describing engine operation; and control means responding to said sampled output so that there are three decision states which act to make the air fuel ratio richer, make the air fuel ratio leaner and not alter the air fuel ratio, thereby reducing oscillation and magnitude of variations of the commanded air fuel ratios about the desired air fuel ratio, said control means determining that a stoichiometric air fuel ratio has been achieved and there is no need to alter the air fuel ratio command when sensing a rapid fluctuation in rich and lean stoichiometry indications due to cylinder to cylinder variation in air fuel ratio corresponding to a state of average cylinder stoichiometry.
sensing means for sensing the quantity of oxygen within the exhaust emission of the engine at a given repetition rate, the time interval between successive oxygen-sensing samples being at least as small as the time interval between successive cylinder firings of said internal combustion engine;
control means coupled to receive the output of said sensing means for controlling the rate of supply of fuel to the engine as a function of the quantity of oxygen sensed by said sensing means, any change in the rate of supply of fuel to the engine being accomplished by a step change, the size of the step being a function of a parameter describing engine operation; and control means responding to said sampled output so that there are three decision states which act to make the air fuel ratio richer, make the air fuel ratio leaner and not alter the air fuel ratio, thereby reducing oscillation and magnitude of variations of the commanded air fuel ratios about the desired air fuel ratio, said control means determining that a stoichiometric air fuel ratio has been achieved and there is no need to alter the air fuel ratio command when sensing a rapid fluctuation in rich and lean stoichiometry indications due to cylinder to cylinder variation in air fuel ratio corresponding to a state of average cylinder stoichiometry.
2. An air fuel ratio feedback type fuel supply system as recited in claim 1 wherein said control means includes:
a biasing means for counting a predetermined number of inputs to said control means describing a first type of air fuel ratio with respect to stoichiometry in comparison to the total number of inputs and generating an output so that the air fuel ratio established by the fuel supply system is of said first type and offset from stoichiometry.
a biasing means for counting a predetermined number of inputs to said control means describing a first type of air fuel ratio with respect to stoichiometry in comparison to the total number of inputs and generating an output so that the air fuel ratio established by the fuel supply system is of said first type and offset from stoichiometry.
3. An air fuel ratio feedback type fuel supply system as recited in claim 2 further comprising:
a throttle position sensor and a manifold absolute pressure sensor, both coupled to said control means, for providing information characterizing the parameter describing engine operation used in determining the step size of a change in the rate of supply of fuel.
a throttle position sensor and a manifold absolute pressure sensor, both coupled to said control means, for providing information characterizing the parameter describing engine operation used in determining the step size of a change in the rate of supply of fuel.
4. An air fuel ratio feedback type fuel supply system as recited in claim 3 wherein:
said sensing means is adapted to sense every 30 milliseconds the quantity of oxygen within the exhaust emission of the engine; and said control means is adapted to change the air fuel ratio in the rich direction if two or less out of ten samples are rich, change the air fuel ratio in the lean direction if two or less out of ten samples are lean, and not change the air fuel ratio if the lean or rich air fuel indications are between three and seven out of ten indications.
said sensing means is adapted to sense every 30 milliseconds the quantity of oxygen within the exhaust emission of the engine; and said control means is adapted to change the air fuel ratio in the rich direction if two or less out of ten samples are rich, change the air fuel ratio in the lean direction if two or less out of ten samples are lean, and not change the air fuel ratio if the lean or rich air fuel indications are between three and seven out of ten indications.
5. A method of controlling the air fuel ratio of an internal combustion engine including the step of:
sampling the quantity of oxygen within the exhaust emission of the engine;
sensing parameters characterizing engine opera-tion; and controlling the rate of supply of fuel to the engine by steps in accordance with at least one of the parameters sensed the direction of the steps being such that a first given percentage or less of rich samples causes the air fuel ratio to be driven rich; a second given percentage or less of lean samples causes the air fuel ratio to be driven lean and an intermediate percentage causes no change in the air fuel ratio.
sampling the quantity of oxygen within the exhaust emission of the engine;
sensing parameters characterizing engine opera-tion; and controlling the rate of supply of fuel to the engine by steps in accordance with at least one of the parameters sensed the direction of the steps being such that a first given percentage or less of rich samples causes the air fuel ratio to be driven rich; a second given percentage or less of lean samples causes the air fuel ratio to be driven lean and an intermediate percentage causes no change in the air fuel ratio.
6. A method of controlling the air fuel ratio as recited in claim 5 further comprising the step of biasing the operating point of the internal combustion engine by:
increasing the number of samples of the type either rich or lean, in which direction the engine operation is being biased with respect to samples of the either type; and changing the size of the air fuel ratio step by amounts related to other engine parameters such as, for example, the rate of change of manifold absolute pressure and engine coolant temperature to provide air fuel ratio control during transient engine operating conditions.
increasing the number of samples of the type either rich or lean, in which direction the engine operation is being biased with respect to samples of the either type; and changing the size of the air fuel ratio step by amounts related to other engine parameters such as, for example, the rate of change of manifold absolute pressure and engine coolant temperature to provide air fuel ratio control during transient engine operating conditions.
7. A method of controlling the air fuel ratio as recited in claim 6 further comprising the step:
varying the rate of sampling the quantity of oxygen within the exhaust emission of the engine thereby varying the frequency with which corrections can be made to the air fuel ratio.
varying the rate of sampling the quantity of oxygen within the exhaust emission of the engine thereby varying the frequency with which corrections can be made to the air fuel ratio.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US16040880A | 1980-06-17 | 1980-06-17 | |
| US160,408 | 1980-06-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1174334A true CA1174334A (en) | 1984-09-11 |
Family
ID=22576786
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000376948A Expired CA1174334A (en) | 1980-06-17 | 1981-05-06 | Statistical air fuel ratio control |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5735140A (en) |
| CA (1) | CA1174334A (en) |
| DE (1) | DE3123260C2 (en) |
| GB (1) | GB2077962B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58172446A (en) * | 1982-04-02 | 1983-10-11 | Honda Motor Co Ltd | Operating state control device of internal-combustion engine |
| DE3303757C1 (en) * | 1983-02-04 | 1984-08-02 | Daimler-Benz Ag, 7000 Stuttgart | Method for controlling the fuel-air ratio for an internal combustion engine |
| DE3327156A1 (en) * | 1983-07-28 | 1985-02-07 | Robert Bosch Gmbh, 7000 Stuttgart | METHOD AND DEVICE FOR (LAMBDA) CONTROL OF THE FUEL MIXTURE FOR AN INTERNAL COMBUSTION ENGINE |
| DE3405916A1 (en) * | 1984-02-18 | 1985-08-22 | Robert Bosch Gmbh, 7000 Stuttgart | MIXING METERING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE |
| DE19510642C2 (en) * | 1994-12-02 | 1997-04-10 | Volkswagen Ag | Method for reducing pollutants in the exhaust gas of an internal combustion engine having multiple cylinders |
| US6260547B1 (en) * | 2000-02-01 | 2001-07-17 | Michael Spencer-Smith | Apparatus and method for improving the performance of a motor vehicle internal combustion engine |
| US6837233B1 (en) | 2002-11-04 | 2005-01-04 | Michael Spencer-Smith | System for enhancing performance of an internal combustion engine |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL156787B (en) * | 1969-03-22 | 1978-05-16 | Philips Nv | DEVICE FOR THE AUTOMATIC REGULATION OF THE AIR-FUEL RATIO OF THE MIXTURE FEEDED TO AN COMBUSTION ENGINE. |
| JPS5028563B1 (en) * | 1969-12-29 | 1975-09-17 | ||
| JPS4972524A (en) * | 1972-11-17 | 1974-07-12 |
-
1981
- 1981-05-06 CA CA000376948A patent/CA1174334A/en not_active Expired
- 1981-06-12 DE DE19813123260 patent/DE3123260C2/en not_active Expired
- 1981-06-15 GB GB8118295A patent/GB2077962B/en not_active Expired
- 1981-06-16 JP JP9292081A patent/JPS5735140A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE3123260A1 (en) | 1982-04-08 |
| JPS5735140A (en) | 1982-02-25 |
| GB2077962B (en) | 1984-03-14 |
| GB2077962A (en) | 1981-12-23 |
| DE3123260C2 (en) | 1986-10-30 |
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