Toyota Jidosha Kabushiki Kaisha

Tomomi Onishi

Shigeki Nakayama

Tomihisa Oda

Hiroki Murata

Akio Matsunaga

Takeru Shirasawa

Masahiro Nagae

Hajime Shimizu

Bungo Kawaguchi

Satoshi Kobayakawa

Masaaki Sato

Akira Yamashita

Isao Matsumoto

Tomoyuki Ono

Takao Fukuma

Satoshi Yamazaki

Teruhiko Miyake

Hiroyuki Haga

Shuichi Kubo

Akiyuki Iemura

Masaaki Satou

Yoshiki Takatori

The present invention discloses an exhaust gas purification system for an internal combustion engine, which is provided with: a low pressure EGR mechanism that is equipped with a low pressure EGR passage and a low pressure EGR valve; a selective reduction type catalyst that is arranged in a portion of the exhaust passage downstream; a supply device which serves to supply an ammonia derived compound to said selective reduction type catalyst; and a control unit that causes said supply device to supply the ammonia derived compound when said low pressure EGR valve is in a valve open state, makes the amount of the ammonia derived compound supplied from said supply device larger in cases where an amount of the low pressure EGR gas flowing through said low pressure EGR passage is large, in comparison with the case where it is small.

Exhaust gas purification system for an internal combustion engine

A soot discharge amount is calculated by multiplying a 'steady discharge amount' by a 'transient correction value.' The steady discharge amount is a Soot discharge amount in a steady operation state, and is acquired through table search. For each of a plurality of factors which affect the Soot discharge amount, a steady value (value obtained through table search) of the factor and a transient value (current value) of the factor are substituted for a characteristic equation which represents a change in the Soot discharge amount with the value of the factor, whereby a steady characteristic value and a transient characteristic value are acquired. The &#x201c;ratio between the steady characteristic value and the transient characteristic value&#x201d; is then calculated for each factor. The transient correction value is obtained by multiplying together all values of the &#x201c;ratio between the steady characteristic value and the transient characteristic value&#x201d; obtained for the factors.

Soot discharge estimating device for internal combustion engines

An exhaust gas purification system for an internal combustion engine, which is provided with: a selective reduction type catalyst arranged in an exhaust passage of the internal combustion engine; a low pressure EGR mechanism that is equipped with a low pressure EGR passage for introducing a part of an exhaust gas flowing through a portion of the exhaust passage downstream of a turbine of a centrifugal supercharger to a portion of an intake passage upstream of a compressor as a low pressure EGR gas, and a low pressure EGR valve for changing a channel cross section of the low pressure EGR passage; a supply device.

An exhaust gas recirculation device of an internal combustion engine () including a low-pressure EGR passage (), a high-pressure EGR passage (), a low-pressure EGR valve () and a high-pressure EGR valve () further includes an air-fuel ratio sensor () that is disposed in the exhaust passage () upstream of the position of its connection with the low-pressure EGR passage (). In the case where a predetermined fuel-cut condition is satisfied, an ECU () estimates the flow amounts of exhaust gas flowing in the low-pressure EGR passage () and the high-pressure EGR passage (), on the basis of the oxygen concentrations acquired by the air-fuel ratio sensor () at timings at which the exhaust gases recirculated into the intake passage () via the low-pressure EGR passage () and via the high-pressure EGR passage () reach the air-fuel ratio sensor (), respectively.

Exhaust gas recirculation device of internal combustion engine, and control method for the device

An exhaust gas recirculation device of an engine () of the invention comprises a first exhaust gas recirculation passage () for connecting an exhaust passage () and an intake passage () to each other and introducing into the intake passage an exhaust gas discharged from a combustion chamber () to the exhaust passage, and a second exhaust gas recirculation passage () for connecting the exhaust passage upstream of a part of the exhaust passage connected to the first exhaust gas recirculation passage and the intake passage downstream of a part of the intake passage connected to the first exhaust gas recirculation passage to each other and introducing into the intake passage the exhaust gas discharged from the combustion chamber to the exhaust passage. The amount of the exhaust gas introduced into the intake passage via the first exhaust gas recirculation passage is controlled to a first target exhaust gas recirculation amount and the amount of the exhaust gas introduced into the intake passage via the second exhaust gas recirculation passage is controlled to a second target exhaust gas recirculation amount. The amount of exhaust gas introduced into the first and second exhaust gas passages is controlled in accordance with an allowable upper flame temperature.

Exhaust gas recirculation device of engine

An exhaust gas control system for an internal combustion engine includes a turbocharger that includes a compressor arranged in an intake passage, and a turbine arranged in an exhaust passage; a low-pressure EGR unit that recirculates a portion of exhaust gas back to the internal combustion engine through a low-pressure EGR passage that provides communication between the exhaust passage, at a portion downstream of the turbine, and the intake passage, at a portion upstream of the compressor; a low-pressure EGR valve that is provided in the low-pressure EGR passage, and that changes the flow passage area of the low-pressure EGR passage; and a valve control unit that executes an opening/closing control over the low-pressure EGR valve. When it is determined that the internal combustion engine is under a predetermined low-temperature environment, the low-pressure EGR valve is kept closed while the internal combustion engine is in the fuel-supply cutoff operation mode.

Exhaust gas control system for internal combustion engine and method for controlling the same

A soot discharge amount is calculated by multiplying a 'steady discharge amount' by a 'transient correction value.' The steady discharge amount is a soot discharge amount in a steady operation state, and is acquired through table search. For each of a plurality of factors which affect the soot discharge amount, a steady value (value obtained through table search) of the factor and a transient value (current value) of the factor are substituted for a characteristic equation which represents a change in the soot discharge amount with the value of the factor, whereby a steady characteristic value and a transient characteristic value are acquired. The &#x201c;ratio between the steady characteristic value and the transient characteristic value&#x201d; is then calculated for each factor. The transient correction value is obtained by multiplying together all values of the &#x201c;ratio between the steady characteristic value and the transient characteristic value&#x201d; obtained for the factors.

An EGR system includes a high-pressure EGR unit and a low-pressure EGR unit. During the steady operation of an internal combustion engine, the high-pressure EGR gas and the low-pressure EGR gas are mixed with each other at a mixture ratio, in which the ratio of the high-pressure EGR gas amount to the entire EGR gas amount is higher than that in a known mixture ratio, and then recirculated back to the internal combustion engine. In the engine speed-up transitional operation period, the opening amount of a high-pressure EGR valve is adjusted to the opening amount that is much smaller than the target opening amount corresponding to the target operation mode. Thus, it is possible to suppress occurrence of the situation where the entire EGR gas amount is excessive in the period in which the low-pressure EGR gas amount does not decrease by a sufficient amount.

EGR system for internal combustion engine and method for controlling the same

An exhaust gas recirculation system includes a high-pressure EGR unit; a low-pressure EGR unit; a high-pressure EGR valve; a low-pressure EGR valve; and an EGR control unit that adjusts the opening amount of the high-pressure EGR valve to a required value for achieving the target EGR rate based on the characteristics of the exhaust gas in the low-pressure EGR passage before the operation mode is changed, and that maintains the required value during a period from when the operation mode is changed until when the low-pressure EGR gas is changed to the exhaust gas discharged from the internal combustion engine in the post-change operation mode.

Exhaust gas recirculation system for internal combustion engine and method for controlling the same

A technique is provided which, in an exhaust gas recirculation apparatus for an internal combustion engine, can calculate a low-pressure EGR rate and a high-pressure EGR rate in an accurate manner, and control the flow rates of both a low pressure EGR passage and a high pressure EGR passage in a closed-loop control manner, thereby to make the temperature of intake air and a supercharging pressure stable and to suppress the deterioration of exhaust emissions as well as the deterioration of power performance. The low pressure EGR rate, representative of the proportion of an amount of low pressure EGR gas to an amount of intake air sucked into the internal combustion engine, and the high pressure EGR rate, representative of the proportion of an amount of high pressure EGR gas to the amount of intake air, are calculated by using a COconcentration in an intake passage at a location downstream of a connection portion of the low pressure EGR passage and upstream of a connection portion of the high pressure EGR passage, a COconcentration in the intake passage at a location downstream the connection portion of the high pressure EGR passage, and a COconcentration of an exhaust gas discharged from the internal combustion engine (S). The low pressure EGR rate and the high pressure EGR rate to be calculated are controlled to individual target values, respectively (S).

Exhaust gas recirculation apparatus for an internal combustion engine

In an exhaust gas recirculation system for an internal combustion engine, which includes a turbocharger; a high-pressure EGR unit; a low-pressure EGR unit; a high-pressure EGR valve; and a low-pressure EGR valve, first, the opening amount of the high-pressure EGR valve is controlled in a feedback manner, and, then, the opening amount of a low-pressure EGR valve is controlled in a feedback manner in a transitional operation period in which the operation mode of the internal combustion engine is changing. In this way, the intake air amount is promptly adjusted to the target intake air amount without causing hunting.

A soot generation amount estimation apparatus obtains a generation speed of a precursor of soot (accordingly, the concentration of the precursor) in consideration of formation of the precursor from fuel, thermal decomposition of the formed precursor, and formation of soot from the formed precursor, and estimates a generation speed of soot (accordingly, the concentration of soot (the generation amount of soot)) in consideration of formation of soot from the precursor, which depends on the concentration of the precursor, and oxidation of the formed soot. The apparatus employs a reaction model in which the reaction process in which soot is generated from fuel is divided into two steps; i.e., a reaction process in which a precursor is generated from fuel and a reaction process in which soot is generated from the precursor. Thus, phenomena, such as a 'delay in soot generation' in the reaction process in which soot is generated from fuel, can be accurately simulated.

Soot generation amount estimation apparatus for internal combustion engine

This apparatus equally divides an injection period TAU into three periods; i.e., front, intermediate, and rear periods, and assumes that first injection (mass Q()) corresponding to the 'front period' is executed at one time at a fuel injection start timing, second injection (mass Q()) corresponding to the 'intermediate period' is executed at one time when &#x2153; TAU has elapsed after the first injection, and third injection (mass Q()) corresponding to the &#x201c;rear period&#x201d; is executed at one time when &#x2153; TAU has elapsed after the second injection. A first gas mixture based on the first injection, a second gas mixture based on the second injection, and a third gas mixture based on the third injection are individually handled, and the excess air ratio of gas mixture, the state (temperature, etc.) of gas mixture, and the emission generation amounts in gas mixture are estimated for each gas mixture.

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Susono, Japan

Tomomi Onishi