EGR control device
AssigneeToyota Jidosha Kabushiki Kaisha
InventorMasayoshi Nakagawa
Life of this patent
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Abstract
An internal combustion engine includes a supercharger having a compressor and a turbine and an EGR apparatus having an exhaust recirculating pipe, an upstream EGR valve and a downstream EGR valve. An electronic control unit fully opens the upstream EGR valve and controls an EGR amount by the downstream EGR valve when a peak value of an exhaust pressure increases excessively. The resulting increase in exhaust volume causes the peak value of the exhaust pressure to fall, and damage to parts of an exhaust system can be avoided. The electronic control unit fully opens the downstream EGR valve and controls the EGR amount by the upstream EGR valve when the peak value of the exhaust pressure decreases excessively. The resulting decrease in the exhaust volume causes the peak value of the exhaust pressure to rise, enabling supercharging.
Claims5
An EGR control device applied to an internal combustion engine which comprises a supercharger having a turbine disposed in an exhaust passage of the internal combustion engine and a compressor disposed in an air intake passage of the internal combustion engine, the EGR control device comprising:
- an EGR passage constitution part which connects an upstream part that is a part of said exhaust passage on an upstream side of said turbine with said air intake passage,
- an upstream EGR valve which is disposed at a first position of said EGR passage constitution part and configured to change upstream passage cross-sectional area that is cross-sectional area of a channel in the first position of said EGR passage constitution part in response to a change of opening of the upstream EGR valve,
- a downstream EGR valve which is disposed at a second position of said EGR passage constitution part, which is on a downstream side of said first position in a flow of an EGR gas that is an exhaust gas flowing through said EGR passage constitution part, and configured to change downstream passage cross-sectional area that is cross-sectional area of a channel in the second position of said EGR passage constitution part in response to a change of opening of the downstream EGR valve, and
- a control part comprising a central processing unit programmed to perform instructions stored in a non-transitory computer-readable medium to control each of the openings of said upstream EGR valve and said downstream EGR valve, and
- said control part being configured to:
- switch an EGR control mode between a first mode and a second mode, wherein the control part controls each of the openings of said upstream EGR valve and said downstream EGR valve such that said upstream passage cross-sectional area is smaller than said downstream passage cross-sectional area and an EGR amount that is a flow rate of said EGR gas is increased or decreased according to the opening of said upstream EGR valve in said first mode, and the control part controls each of the openings of said upstream EGR valve and said downstream EGR valve such that said downstream passage cross-sectional area is smaller than said upstream passage cross-sectional area and said EGR amount is increased or decreased according to the opening of said downstream EGR valve in said second mode,
- switch said EGR control mode to said second mode when an operational state of said internal combustion engine becomes a first operational state in which a peak value of an exhaust pressure accompanied by exhaust pulsation on an upstream side of said turbine is a first threshold or more, in a case where said EGR control mode is said first mode, and
- switch said EGR control mode to said first mode when an operational state of said internal combustion engine becomes a second operational state in which a peak value of said exhaust pressure is less than a second threshold that is said first threshold or less, in a case where said EGR control mode is said second mode.
Dependencies are inferred from the claim text.