Dual mode hybrid control for electronic fuel injection system
First Claim
1. A dual mode hybrid control system for controlling the operation of an electronic fuel management system which regulates the air/fuel ratio of an internal combustion engine, the engine operable at different rotational speeds and having a catalytic converter for reducing exhaust gas emissions, said hybrid control system comprising:
- means for generating an electrical signal for controlling the operation of said electronic fuel management system;
closed loop comparator means coupled to said signal-generating means for establishing a closed loop control mode for enabling said signal-generating means to normally operate said electronic fuel management system at air-fuel ratios within a conversion window of maximum efficiency for the converter while said engine operates within a predetermined range of driving speeds to achieve optimal reduction of engine emissions, said range of speeds including those engine conditions at which the level of NOx formation is detrimental and should be converted by said converter; and
open loop comparator means coupled to said signal-generating means and responsive to the attainment of a driving speed outside of said predetermined range for switching to an open loop control mode for clamping the output of said signal-generating means to a predetermined air/fuel ratio value to operate said electronic fuel management system at a relatively lean air/fuel ratio not within said conversion window for improved fuel economy.
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Accused Products
Abstract
A dual mode control system for operating an electronic fuel injection system for an internal combustion engine so as to achieve an optimal compromise between engine emissions, fuel economy and driveability. A closed loop control circuit is provided which senses the amount of oxygen in the engine exhaust and normally drives an integrator in a closed loop mode of operation to operate the electronic fuel injection system at the stoichiometric air/fuel ratio at which the best conversion efficiency of hydrocarbons, carbon monoxide and nitrous oxides occur. An open loop control circuit senses high speed operation where hydrocarbons and carbon monoxide conversion are normally high and where nitrous oxide emission is not critical and clamps the output of the integrator to a predetermined value which operates the electronic fuel injection system at a nonstoichiometric, relatively lean, air/fuel ratio for improved fuel economy. Further open loop control circuitry may be provided to sense very low speed, low engine load operation where nitrous oxide emission is negligible for similarly switching to an open loop mode of operation with the integrator output clamped. An override circuit may be provided which senses engine acceleration which normally requires a relatively rich air/fuel ratio for good driveability and overrides the clamped integrator output to restore the closed loop mode of operation regardless of the engine speed thereby achieving an optimal compromise between engine emissions, fuel economy and drivability.
23 Citations
30 Claims
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1. A dual mode hybrid control system for controlling the operation of an electronic fuel management system which regulates the air/fuel ratio of an internal combustion engine, the engine operable at different rotational speeds and having a catalytic converter for reducing exhaust gas emissions, said hybrid control system comprising:
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means for generating an electrical signal for controlling the operation of said electronic fuel management system; closed loop comparator means coupled to said signal-generating means for establishing a closed loop control mode for enabling said signal-generating means to normally operate said electronic fuel management system at air-fuel ratios within a conversion window of maximum efficiency for the converter while said engine operates within a predetermined range of driving speeds to achieve optimal reduction of engine emissions, said range of speeds including those engine conditions at which the level of NOx formation is detrimental and should be converted by said converter; and open loop comparator means coupled to said signal-generating means and responsive to the attainment of a driving speed outside of said predetermined range for switching to an open loop control mode for clamping the output of said signal-generating means to a predetermined air/fuel ratio value to operate said electronic fuel management system at a relatively lean air/fuel ratio not within said conversion window for improved fuel economy. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A dual mode control circuit for controlling the operation of an electronic fuel injection system for an internal combustion engine operable at various engine speeds and having an engine exhaust with a catalytic converter for reducing emissions from said exhaust, said control circuit comprising:
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integrator means whose output controls the operation of said electronic fuel injection system; means for sensing the amount of oxygen present in the engine exhaust and generating an electrical signal indicative thereof; first comparator means establishing a closed loop between said oxygen sensing means and said integrator means and responsive to said oxygen-indicative electrical signal for normally causing the output of said integrator means to vary as the quantity of oxygen in said engine exhaust varies so as to maintain an optimum air/fuel ratio window near stoichiometric for minimal engine emissions, said optimum air/fuel ratio being within the maximum conversion efficiency window of said converter; speed sensing means for generating signals indicative of engine speed; and second comparator means coupled between said speed sensing means and said integrator means and responsive to said engine speed having exceeded a predetermined limit for clamping the output of said integrator means at a predetermined limit for clamping the output of said integrator means at a predetermined level effective to operate said fuel injection system at a predetermined, non-stoichiometric, relatively lean air/fuel ratio outside said conversion window for improved fuel economy, said predetermined limit corresponding to a driving speed where the conversion of the NOx component of the emissions of the engine exhaust is not critical to emission control.
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8. A dual mode control circuit for controlling the operation of an electronic fuel injection system for an internal combustion engine operable at various engine speeds comprising and having a catalytic converter for the reduction of exhaust gas emissions:
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closed loop means including an integrator whose output normally varies to maintain the operation of said electronic fuel injection system at near the stoichiometric air/fuel ratio which is within the window of maximum conversion efficiency for said converter; and means for establishing a range of driving speeds within which said closed loop means is operable to maintain said near stoichiometric air/fuel ratio to obtain optimal conversion of hydrocarbons, carbon monoxide and nitrous oxides, said range-establishing means being responsive to driving speeds outside of said range for clamping the output of said integrator in an open loop mode of operation to operate said electronic fuel injection system at a relatively lean air/fuel ratio for improved fuel economy since at speeds below said established range, hydrocarbons and carbon monoxide conversion is normally high and nitrous oxide emissions are negligible when engine loads are low and since at speeds above said established range nitrous oxide emissions are not usually critical in areas where high speed driving is permitted.
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9. In an internal combustion engine operable at various rotational speeds and having an engine exhaust with a catalytic converter for the reduction of emissions and an electronic fuel injection system for controlling the quantity of fuel supplied to the engine, a dual mode control for operating the electronic fuel injection system comprising:
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means for generating signals indicative of the oxygen present in the engine exhaust; means coupled between said means for generating signals indicative of the oxygen present in the engine exhaust and said electronic fuel injection system for establishing a closed loop control mode of operation and including an integrator whose output varies as the oxygen in the engine exhaust varies for normally maintaining said engine operating at optimal emission-reducing air/fuel ratios near stoichiometric for maximum conversion efficiency of said converter; means for generating signals indicative of the speed of the engine; means coupled between said means for generating speed indicative signals and said integrator and responsive to the engine speed having passed a threshold corresponding to a predetermined driving speed for switching to an open loop mode of operation and clamping the output of said integrator to a predetermined value to operate said engine at a predetermined leaner air/fuel ratio for improved fuel economy; means for generating a signal indicative of the acceleration of said engine; and means responsive to a predetermined acceleration for unclamping said integrator output and restoring said closed loop mode of operation.
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10. A dual mode hybrid control system for controlling the operation of an electronic fuel management system which regulates the air/fuel ratio of an internal combustion engine, the engine operable at different rotational speeds and having a catalytic converter for reducing exhaust gas emissions, said hybrid control system comprising:
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means for generating an electrical signal for controlling the operation of said electronic fuel management system; means for generating electrical signals indicative of the speed of the engine; closed loop comparator means coupled to said signal-generating means for establishing a closed loop control mode for enabling said signal-generating means to normally operate said electronic fuel management system at air-fuel ratios within a conversion window of maximum efficiency for the converter while said engine operates within a predetermined range of driving speeds to achieve optimal reduction of engine emissions, said range of speeds including those engine conditions at which the level of NOx formation is detrimental and should be converted by said converter; open loop comparator means coupled to said signal-generating means and responsive to the attainment of a driving speed outside of said predetermined range for switching to an open loop control mode for clamping the output of said signal-generating means to a predetermined air/fuel ratio value to operate said electronic fuel management system at a relatively lean air/fuel ratio not within said conversion window for improved fuel economy; and said open loop comparator means including a comparator having first and second inputs and a comparator output, said first comparator input being coupled to means for establishing a predetermined threshold level indicative of a driving speed and said second input being coupled to said source of speed indicative signals such that the output of said comparator means will normally allow said signal-generating means to operate in said closed loop control mode so long as said engine speed is below said predetermined threshold level but will switch the operation of said signal-generating means to said predetermined value for effecting said relatively lean air/fuel ratio whenever said predetermined threshold level of driving speed has been exceeded.
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11. A dual mode hybrid control system for controlling the operation of an electronic fuel management system which regulates the air/fuel ratio of an internal combustion engine, the engine operable at different rotational speeds and having a catalytic converter for reducing exhaust gas emissions, said hybrid control system comprising:
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means for generating an electrical signal for controlling the operation of said electronic fuel management system; means for generating electrical signals indicative of the speed of the engine; closed loop comparator means coupled to said signal-generating means for establishing a closed loop control mode for enabling said signal-generating means to normally operate said electronic fuel management system at air-fuel ratios within a conversion window of maximum efficiency for the converter while said engine operates within a predetermined range of driving speeds to achieve optimal reduction of engine emissions, said range of speeds including these engine conditions at which the level of NOx formation is detrimental and should be converted by said converter; open loop comparator means coupled to said signal-generating means and responsive to the attainment of a driving speed outside of said predetermined range for switching to an open loop control mode for clamping the output of said signal-generating means to a predetermined air/fuel ratio value to operate said electronic fuel management system at a relatively lean air/fuel ratio not within said conversion window for improved fuel economy; and
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- 12. said open loop comparator means including first and second comparators each having one input coupled to said source of speed indicative signals, the other input of one of said comparators being coupled to means for establishing a predetermined low speed driving threshold and the second input of the other of said comparators being coupled to means for establishing a predetermined high speed driving threshold such that so long as the engine operates between said low threshold and said high threshold, the outputs of said first and second comparators enable said signal-generating means to operate in said closed loop control mode, but whenever the engine speed falls below said low threshold or exceeds said high threshold of driving speed the output of one of said comparators switches said signal-generating means to operate in said open loop control mode by clamping the output of said signal-generating means to said predetermined value to operate said electronic fuel management system at said relatively lean air/fuel ratio.
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13. A dual mode hybrid control system for controlling the operation of an electronic fuel management system which regulates the air/fuel ratio of an internal combustion engine, the engine operable at different rotational speeds and having a catalytic converter for reducing exhaust gas emissions, said hybrid control system comprising:
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means for generating an electrical signal for controlling the operation of said electronic fuel management system; means for generating electrical signals indicative of engine speed; means for sensing the quantity of oxygen present at the exhaust of said engine and for generating an electrical signal indicative thereof; closed loop comparator means coupled to said signal-generating means for establishing a closed loop control mode for enabling said signal-generating means to normally operate said electronic fuel management system at air-fuel ratios within a conversion window of maximum efficiency for the converter while said engine operates within a predetermined range of driving speeds to achieve optimal reduction of engine emissions, said range of speeds including those engine conditions at which the level of NOx formation is detrimental and should be converted by said converter; open loop comparator means coupled to said signal-generating means and responsive to the attainment of a driving speed outside of said predetermined range for switching to an open loop control mode for clamping the output of said signal-generating means to a predetermined air/fuel ratio value to operate said electronic fuel management system at a relatively lean air/fuel ratio not within said conversion window for improved fuel economy; wherein said electrical signal-generating means comprises an electrical integrator circuit including an operational amplifier having first and second inputs and an integrator output, the output of said closed loop comparator means being coupled to the first input of said operational amplifier and resistive means for establishing said predetermined value of clamped voltage outputted during the open loop mode of operation being coupled to the second input of said operational amplifier, capacitive means being coupled between the first input of said operational amplifier and said integrator output, and a series combination including a resistor and a transistor switch being connected in parallel across said capacitive means such that the control electrode of said transistor switch is coupled to the output of said open loop comparator means to operate said switch for selectively clamping or unclamping the output of said integrator; wherein said closed loop comparator means includes a comparator having first and second inputs and a comparator output, the first comparator input being coupled to said means for generating electrical signals indicative of the quantity of oxygen present at said engine exhaust, the second comparator input being coupled to resistive means for establishing a reference level about which the oxygen level will vary for maintaining the stoichiometric air/fuel ratio during the closed loop mode operation, and said comparator output being coupled to the first input of said operational amplifier of said integrator circuit to complete a closed loop between the oxygen sensing means and the electronic fuel management system; and wherein said open loop comparator means includes a second comparator having first and second inputs and a comparator output, the first input of said second comparator being coupled to said means for generating speed indicative signals and the second input of said second comparator being coupled to resistive means for establishing a predetermined speed threshold below which the output of said second comparator will be maintained at a first value and above which the output of said second comparator will attain a second value, the output of said second comparator means being coupled to the control electrode of said switching transistor of said integrator circuit such that when the output of said second comparator means is in said first state, said switching transistor remains in a normally non-conductive state and said integrator circuit operates in said closed loop control mode, but when the output of said second comparator attains said second state said switching transistor is switched to a conductive state to clamp the output of said integrator circuit at said predetermined value established by the resistive means coupled to the second input of said operational amplifier thereby switching the operation of said integrator circuit to said open loop control mode to operate said electronic fuel management system to maintain said relatively lean air/fuel ratio.
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16. A dual mode hybrid control system for controlling the operation of an electronic fuel management system which regulates the air/fuel ratio of an internal combustion engine, the engine operable at different rotational speeds and having a catalytic converter for reducing exhaust gas emissions, said hybrid control system comprising:
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means for generating an electrical signal for controlling the operation of said electronic fuel management system; means for generating electrical signals indicative of engine speed; means for sensing the quantity of oxygen present at the exhaust of said engine and for generating an electrical signal indicative thereof; closed loop comparator means coupled to said signal-generating means for establishing a closed loop control mode for enabling said signal-generating means to normally operate said electronic fuel management system at air-fuel ratios within a conversion window of maximum efficiency for the converter while said engine operates within a predetermined range of driving speeds to achieve optimal reduction of engine emissions, said range of speeds including those engine conditions at which the level of NOx formation is detrimental and should be converted by said converter; open loop comparator means coupled to said signal-generating means and responsive to the attainment of a driving speed outside of said predetermined range for switching to an open loop control mode for clamping the output of said signal-generating means to a predetermined air/fuel ratio value to operate said electronic fuel management system at a relatively lean air/fuel ratio not within said conversion window for improved fuel economy; wherein said electrical signal-generating means comprises an electrical integrator circuit including an operational amplifier having first and second inputs and an integrator output, the output of said closed loop comparator means being coupled to the first input of said operational amplifier and resistive means for establishing said predetermined value of clamped voltage outputted during the open loop mode of operation being coupled to the second input of said operational amplifier, capactive means being coupled between the first input of said operational amplifier and said integrator output, and a series combination including a resistor and a transistor switch being connected in parallel across said capacitive means such that the control electrode of said transistor switch is coupled to the output of said open loop comparator means to operate said switch for selectively clamping or unclamping the output of said integrator; wherein said closed loop comparator means includes a comparator having first and second inputs and a comparator output, the first comparator input being coupled to said means for generating electrical signals indicative of the quantity of oxygen present at said engine exhaust, the second comparator input being coupled to resistive means for establishing a reference level about which the oxygen level will vary for maintaining the stoichiometric air/fuel ratio during the closed loop mode operation, and said comparator output being coupled to the first input of said operational amplifier of said integrator circuit to complete a closed loop between the oxygen sensing means and the electronic fuel management system; and wherein said open loop comparator means includes second and third comparators each having first and second inputs and a comparator output, the first input of each of said second and third comparators being coupled to said means for generating speed-indicative pulses, the second input of said second comparator being coupled to resistive means for establishing a predetermined low speed threshold, the second input of said third comparator being coupled to resistive means for establishing a predetermined high speed threshold, and the outputs of said second and third comparator being resistively coupled to the control electrode of said switching transistor of said integrator circuit such that when the speed of said engine is between said low speed threshold and said high speed threshold, the signal outputted from said second and third comparators will enable said integrator circuit to operate in said closed loop control mode, but when the engine speed falls below said low speed threshold or exceeds said high speed threshold the outputs from said second or third comparator will switch said switching transistor to a conductive state thereby operating said integrator circuit in said open loop control mode and clamping the output of said integrator circuit to said predetermined value to operate the electronic fuel management system at said relatively lean air/fuel ratio.
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19. A dual mode control circuit for controlling the operation of an electronic fuel injection system for an internal combustion engine operable at various engine speeds and having an engine exhaust with a catalytic converter for reducing emissions from said exhaust, said control circuit comprising:
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integrator means whose output controls the operation of said electronic fuel injection system; means for sensing the amount of oxygen present in the engine exhaust and generating an electrical signal indicative thereof; first comparator means establishing a closed loop between said oxygen sensing means and said integrator means and responsive to said oxygen-indicative electrical signal for normally causing the output of said integrator means to vary as the quantity of oxygen in said engine exhaust varies so as to maintain an optimum air/fuel ratio window near stoichiometric for minimal engine emissions, said optimum air/fuel ratio being within the maximum conversion efficiency window of said converter; speed sensing means for generating signals indicative of engine speed; second comparator means coupled between said speed sensing means and said integrator means, responsive to said engine speed having exceeded a predetermined limit for clamping the output of said integrator means at a predetermined level effective to operate said fuel injection system at a predetermined, non-stoichiometric, relatively lean air/fuel ratio outside said conversion window for improved fuel economy, said predetermined limit corresponding to a driving speed where the conversion of the NOx component of the emissions of the engine exhaust is not critical to emission control; and means responsive to a predetermined engine acceleration for disabling said second comparator means to unclamp the output of said integrator means and restore closed loop operation in said window near the stoichiometric air/fuel ratio.
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21. A dual mode control circuit for controlling the operation of an electronic fuel injection system for an internal combustion engine operable at various engine speeds and having an engine exhaust with a catalytic converter for reducing emissions from said exhaust, said control circuit comprising:
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integrator means whose output controls the operation of said electronic fuel injection system; means for sensing the amount of oxygen present in the engine exhaust and generating an electrical signal indicative thereof; first comparator means establishing a closed loop between said oxygen sensing means and said integrator means and responsive to said oxygen-indicative electrical signal for normally causing the output of said integrator means to vary as the quantity of oxygen in said engine exhaust varies so as to maintain an optimum air/fuel ratio window near stoichiometric for minimal engine emissions, said optimum air/fuel ratio being within the maximum conversion efficiency window of said converter; speed sensing means for generating signals indicative of engine speed; second comparator means coupled between said speed sensing means and said integrator means, responsive to said engine speed having exceeded a predetermined limit, for clamping the output of said integrator means at a predetermined level effective to operate said fuel injection system at a predetermined, non-stoichiometric, relatively lean air/fuel ratio outside said conversion window for improved fuel economy, said predetermined limit corresponding to a driving speed where the conversion of the NOx component of the emissions of the engine exhaust is not critical to emission control; and wherein said integrator means includes an operational amplifier having one input coupled to the output of said first comparator means, a second input coupled to variable resistive means for selecting said predetermined level of voltage outputted from said integrator means when its output is clamped during open loop operation for determining said predetermined, non-stoichiometric, relatively lean air/fuel ratio for improved fuel economy and an integrator output for supplying control signals to operate said electronic fuel injection system, a capacitive means coupled between the first input of said operational amplifier and said integrator output, and a series path connected in parallel across said capactive means, said series path including a resistor and a switching transistor, said switching transistor having a control electrode coupled to the output of said second comparator means such that while said switching transistor is maintained in its normally non-conducting state, said integrator means operates in said closed loop mode to maintain said stoichiometric air/fuel ratio, but when said switching transistor is triggered to a conductive state, the output of said operational amplifier is clamped to a level determined by the resistive means at the second input of said operational amplifier to operate said integrator means in said open loop mode thereby operating said electronic fuel injection system at said predetermined non-stoichiometric relatively lean air/fuel ratio. - View Dependent Claims (23, 24)
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26. A dual mode control circuit for controlling the operation of an electronic fuel injection system for an internal combustion engine operable at various engine speeds comprising and having a catalytic converter for the reduction of exhaust gas emissions:
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closed loop means including an integrator whose output normally varies to maintain the operation of said electronic fuel injection system at near the stoichiometric air/fuel ratio which is within the window of maximum conversion efficiency for said converter; means for establishing a range of driving speeds within which said closed loop means is operable to maintain said near stoichiometric air/fuel ratio to obtain optimal conversion of hydrocarbons, carbon monoxide and nitrous oxides, said range-establishing means being responsive to driving speeds outside of said range for clamping the output of said integrator in an open loop mode of operation to operate said electronic fuel injection system at a relatively lean air/fuel ratio for improved fuel economy since at speeds below said established range, hydrocarbons and carbon monoxide conversion is normally high and nitrous oxide emissions are negligible when engine loads are low and since at speeds above said established range nitrous oxide emissions are not usually critical in areas where high speed driving is permitted; and wherein said means for establishing the range of driving speeds includes a first comparator having a first input coupled to said means for generating speed indicative signals, first threshold determining means for generating an electrical signal indicative of the predetermined low speed limit of said range coupled to the second input of said comparator such that the output of said first comparator will go "low" whenever the speed is above said predetermined low speed threshold limit established by said first threshold means and will go "high" whenever the speed drops below said low speed threshold level, a second comparator having a first input coupled to said means for generating speed indicative signals, a second threshold determining means for generating an electrical signal indicative of the predetermined high speed limit of speed range coupled to the second input of said second comparator such that the output of said second comparator will go "low" whenever the speed is below said predetermined high speed threshold limit established by said second threshold means and the output of said second comparator will go "high" whenever the speed exceeds said high speed threshold limit, means for coupling the outputs of said first and second comparators to said integrator, said integrator being responsive to the presence of a "low" signal for maintaining a closed loop mode of operation but being responsive to the presence of a "high" signal for switching to an open loop mode of operation and clamping the output of said integrator to a predetermined voltage for operating said electronic fuel injection system at a non-stoichiometric relatively lean air/fuel ratio in the range of from 15 to 1 to 19 to 1 for improved fuel economy. - View Dependent Claims (28, 29, 30)
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Specification