Method and system for vacuum control
AssigneeFord Global Technologies, LLC
InventorsJoseph Norman Ulrey, Thomas G. Leone, William Charles Ruona, Gopichandra Surnilla, Ross Dykstra Pursifull, John D. Russell
Life of this patent
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Abstract
Methods and systems are provided for controlling and coordinating control of a post-catalyst exhaust throttle and an EGR valve to expedite catalyst heating. By closing both valves during an engine cold start, an elevated exhaust backpressure and increased heat rejection at an EGR cooler can be synergistically used to warm each of an engine and an exhaust catalyst. The valves may also be controlled to vary an amount of exhaust flowing through an exhaust venturi so as to meet engine vacuum needs while providing a desired amount of engine EGR.
Claims20
A method for an engine, comprising:
- while recirculating an amount of exhaust gas to an engine intake,
- closing a post-catalyst exhaust throttle to increase vacuum generation at an exhaust ejector;
- and
- closing an EGR valve to maintain the amount of exhaust gas recirculation.
A method for an engine, comprising:
- operating the engine with exhaust gas recirculation;
- and
- in response to a vacuum requirement,
- reducing an opening of each of a post-catalyst exhaust throttle and an EGR valve to increase exhaust flow through an EGR cooler and then through an exhaust ejector;
- and
- drawing vacuum at the ejector.
An engine system, comprising:
- an engine including an intake and an exhaust;
- a throttle downstream of a catalyst in the engine exhaust;
- an exhaust gas recirculation (EGR) system including an EGR take-off for recirculating catalyst-treated exhaust gas from upstream of the exhaust throttle to the engine intake, the EGR take-off including an EGR cooler upstream of an EGR valve, and a bypass passage coupling an outlet of the EGR cooler with the engine exhaust, downstream of the exhaust throttle, the bypass passage including an ejector;
- and
- a controller including a non-transitory computer-readable medium with instructions for:
- operating the engine system in a first EGR mode with the exhaust throttle more open to recirculate a portion of exhaust gas to the engine intake while directing a first, smaller amount of exhaust gas through the EGR cooler and then through the ejector;
- and
- operating the engine system in a second EGR mode with the exhaust throttle more closed to recirculate the portion of exhaust gas to the engine intake while directing a second, larger amount of exhaust gas through the EGR cooler and then through the ejector.
Dependencies are inferred from the claim text.