Mode transition control scheme for internal combustion engines using unequal fueling
First Claim
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1. A mode transition method for controlling torque produced by an internal combustion engine, the engine having a plurality of cylinders, an exhaust system containing one or more emission aftertreatment devices, and an engine controller operably connected to the engine for controlling the relative air-fuel ratio supplied to the cylinders, the method comprising the steps of:
- operating at least one cylinder at a lean relative air-fuel ratio in response to an indication of desired torque; and
operating at least one other cylinder at a rich relative air-fuel ratio to reduce emissions which would otherwise be caused by operating said at least one cylinder at said lean relative air-fuel ratio.
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Abstract
A control method and system are disclosed for managing torque during a transition in an internal combustion engine. Spark timing and unequal delivery of fuel to engine cylinders both impact torque and are used to provide smooth torque during a transition.
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Citations
20 Claims
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1. A mode transition method for controlling torque produced by an internal combustion engine, the engine having a plurality of cylinders, an exhaust system containing one or more emission aftertreatment devices, and an engine controller operably connected to the engine for controlling the relative air-fuel ratio supplied to the cylinders, the method comprising the steps of:
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operating at least one cylinder at a lean relative air-fuel ratio in response to an indication of desired torque; and
operating at least one other cylinder at a rich relative air-fuel ratio to reduce emissions which would otherwise be caused by operating said at least one cylinder at said lean relative air-fuel ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
computing said desired torque during said mode transition; and
operating said at least one cylinder at said rich relative air-fuel ratio and said at least one other cylinder at said lean relative air-fuel ratio to provide said desired torque during said mode transition.
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5. A mode transition method according to claim 1, comprising the additional steps of:
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computing said desired torque during said mode transition; and
operating said at least one cylinder at said rich relative air-fuel ratio, operating said at least one other cylinder at said lean relative air-fuel ratio, and providing a spark timing which is retarded from a predetermined spark timing to provide said desired torque during said mode transition.
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6. A mode transition method according to claim 5, wherein said predetermined spark timing is a spark timing which provides the maximum torque.
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7. A mode transition method according to claim 2, wherein said desired relative air-fuel ratio is substantially a stoichiometric relative air-fuel ratio.
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8. A mode transition method according to claim 1, wherein the mode transition comprises a reactivation of a portion of the cylinders, wherein the engine is a variable displacement engine.
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9. A mode transition method according to claim 1, wherein the mode transition comprises a deactivation of a portion of the cylinders, wherein the engine is a variable displacement engine.
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10. A mode transition method according to claim 1, wherein the mode transition comprises a change in compression ratio, wherein the engine comprises means to vary compression ratio.
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11. A mode transition method according to claim 1, wherein the mode transition comprises a transition among gears in a transmission coupled to the engine.
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12. A mode transition method according to claim 1, wherein the mode transition comprises a traction control event.
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13. A mode transition method for controlling torque produced by an internal combustion engine, the engine having a plurality of cylinders, an exhaust system containing one or more emission aftertreatment devices, and an engine controller operably connected to the engine for controlling the relative air-fuel ratio supplied to the cylinders, the method comprising the steps of:
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operating at least one cylinder at a lean relative air-fuel ratio to reduce torque; and
operating at least one other cylinder at a rich relative air-fuel ratio to provide a desired relative air-fuel ratio to the aftertreatment device. - View Dependent Claims (14, 15, 16)
computing a desired torque during said mode transition; and
operating said at least one cylinder at said rich relative air-fuel ratio and said at least one other cylinder at said lean relative air-fuel ratio to provide said desired torque during said mode transition.
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16. A mode transition method according to claim 13, comprising the additional steps of:
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computing a desired torque during said mode transition; and
operating said at least one cylinder at said rich relative air-fuel ratio, operating said at least one other cylinder at said lean relative air-fuel ratio, and providing a spark timing which is retarded from a predetermined spark timing to provide said desired torque during said mode transition.
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- 17. A system for controlling torque during a transition of operating mode in an internal combustion engine, the engine having a plurality of cylinders, a throttle valve disposed in an air intake duct, an engine exhaust system containing one or more emission aftertreatment devices, and an engine controller operably connected to the engine for controlling the relative air-fuel ratio to change torque toward a desired torque supplied by the cylinders, wherein said engine controller provides to at least one cylinder a lean relative air-fuel ratio and to at least one other cylinder a rich relative air-fuel ratio to reduce emissions which would otherwise be caused by operating said at least one cylinder at a lean relative air-fuel ratio.
Specification