Abstract: An exhaust gas recirculation device of an internal combustion engine (1) including a low-pressure EGR passage (20), a high-pressure EGR passage (21), a low-pressure EGR valve (23) and a high-pressure EGR valve (24) further includes an air-fuel ratio sensor (12) that is disposed in the exhaust passage (4) upstream of the position of its connection with the low-pressure EGR passage (20). In the case where a predetermined fuel-cut condition is satisfied, an ECU (30) estimates the flow amounts of exhaust gas flowing in the low-pressure EGR passage (20) and the high-pressure EGR passage (21), on the basis of the oxygen concentrations acquired by the air-fuel ratio sensor (12) at timings at which the exhaust gases recirculated into the intake passage (3) via the low-pressure EGR passage (20) and via the high-pressure EGR passage (21) reach the air-fuel ratio sensor (12), respectively.

Abstract: In a feedback control system in which a base gain having a constant value or a variable gain is set as a feedback gain in accordance with the state of the system and an input value is calculated based on a function having, as variables, a proportional term and an integral term, the integral term is recalculated when a discriminant value obtained by substituting a base proportional term calculated using the base gain for the proportional term and a normal integral term calculated using the feedback gain for the integral term in the function is larger than an upper limit value. The integral term is recalculated in such a way that a value obtained by substituting the base proportional term for the proportional term and the recalculated integral term for the integral term in the function becomes equal to or smaller than the upper limit value.

Abstract: In a gas-mixture-nonuniformity acquisition apparatus for an internal combustion engine, the nonuniformity of fuel concentration within a gas mixture is acquired under the assumption that, in a process in which a cylinder interior gas taken into a combustion chamber of the engine and fuel injected into the combustion chamber mix together to form a gas mixture, a collision reaction repeatedly takes place within the gas mixture in such a manner that, due to collision of two gas volumes having different fuel mass ratios, respective portions of the two gas volumes mix together, and the mixed portions separate from the corresponding gas volumes and form a portion or the entirety of another gas volume having a fuel mass ratio different from those of the two gas volumes.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: In a gas mixture temperature estimation method for an internal combustion engine, before a forefront portion of a gas mixture reaches an inner wall surface of the combustion chamber, the gas mixture temperature is calculated in accordance with a predetermined equation which is based on the assumption that no head exchange occurs between the gas mixture and cylinder interior gas which exists around the gas mixture without mixing with fuel. After the gas mixture forefront portion reaches the inner wall surface of the combustion chamber, the gas mixture temperature calculated in accordance with the equation is corrected in consideration of the quantity of heat transfer between the gas mixture and the cylinder interior gas and the quantity of heat transfer between the gas mixture and the wall.

Abstract: In a gas mixture temperature estimation method for an internal combustion engine, before a forefront portion of a gas mixture reaches an inner wall surface of the combustion chamber, the gas mixture temperature is calculated in accordance with a predetermined equation which is based on the assumption that no head exchange occurs between the gas mixture and cylinder interior gas which exists around the gas mixture without mixing with fuel. After the gas mixture forefront portion reaches the inner wall surface of the combustion chamber, the gas mixture temperature calculated in accordance with the equation is corrected in consideration of the quantity of heat transfer between the gas mixture and the cylinder interior gas and the quantity of heat transfer between the gas mixture and the wall.

Abstract: 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(1)) corresponding to the “front period” is executed at one time at a fuel injection start timing, second injection (mass Q(2)) corresponding to the “intermediate period” is executed at one time when ? TAU has elapsed after the first injection, and third injection (mass Q(3)) corresponding to the “rear period” is executed at one time when ? 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.

Abstract: The present apparatus calculates a mass ma (mass ratio ma/mf) of mixing-gas-forming cylinder interior gas, which is a portion of cylinder interior gas to be mixed with a forefront portion of injected fuel vapor having a mass of mf, on the basis of a predetermined empirical formula. Subsequently, under the assumption that heat exchange with the outside does not occur, the apparatus calculates an adiabatic gas mixture temperature Tmix of the gas mixture forefront portion on the basis of the heat quantity of the fuel vapor having a mass of mf and the heat quantity of the mixing-gas-forming cylinder interior gas having a mass of ma. Subsequently, in consideration of an amount of heat that the gas mixture forefront portion receives from peripheral cylinder interior gas mainly via a circumferential surface thereof, the apparatus estimates a final gas mixture temperature Tmixfin of the gas mixture forefront portion (i.e.

Abstract: This control apparatus obtains a relation (trade-off line) between NOx generation amount and PM generation amount with EGR ratio serving as a parameter from an NOx generation amount estimation model which calculates the NOx generation amount on the basis of the oxygen mole concentration of intake gas and a PM generation amount estimation model which calculates the PM generation amount on the basis of an excess air factor. Further, the control apparatus obtains a straight line (ratio determination line) which passes through a point (appropriate point A) corresponding to a combination of steady-condition appropriate values of the NOx generation amount and the PM generation amount under the present operating conditions and which has a slope K determined in consideration of a regulation value based on a law relating to emission control.

Abstract: A gas-mixture-ignition-time estimation apparatus for an internal combustion engine estimates the temperature of a premixed gas mixture for PCCI combustion (i.e., cylinder interior temperature Tg), while relating it to the angle CA, on the basis of a state quantity of the cylinder interior gas at the time of start of compression (CAin) (heat energy of the cylinder interior gas at the time of start of compression), the amount of a change in the state quantity of the cylinder interior gas attributable to compression in a compression stroke (minute piston work), and the heat generation quantity of a cool flame generated in PCCI combustion prior to autoignition (hot flame) (cool flame heat generation quantity Aqlto). A time when the cylinder interior temperature Tg reaches a predetermined autoignition start temperature Tig is estimated as an autoignition start time (Caig) of the premixed gas mixture related to PCCI combustion.

Abstract: This control apparatus obtains a relation (trade-off line) between NOx generation amount and PM generation amount with EGR ratio serving as a parameter from an NOx generation amount estimation model which calculates the NOx generation amount on the basis of the oxygen mole concentration of intake gas and a PM generation amount estimation model which calculates the PM generation amount on the basis of an excess air factor. Further, the control apparatus obtains a straight line (ratio determination line) which passes through a point (appropriate point A) corresponding to a combination of steady-condition appropriate values of the NOx generation amount and the PM generation amount under the present operating conditions and which has a slope K determined in consideration of a regulation value based on a law relating to emission control.

Abstract: In an NOx discharge quantity estimation method for an internal combustion engine equipped with an EGR apparatus, the gas components (e.g., oxygen molecules and NOx) of intake gas taken into a combustion chamber are assumed to be uniformly distributed throughout the entire region of the combustion chamber. Under such assumption, the combustion chamber is divided into a combustion region (region B) and a non-combustion region (region A) by making use of the ratio of the “mass of oxygen consumed as a result of combustion” to the “total mass of oxygen taken in the combustion chamber.

Abstract: A gas-mixture-ignition-time estimation apparatus for an internal combustion engine estimates the temperature of a premixed gas mixture for PCCI combustion (i.e., cylinder interior temperature Tg), while relating it to the angle CA, on the basis of a state quantity of the cylinder interior gas at the time of start of compression (CAin) (heat energy of the cylinder interior gas at the time of start of compression), the amount of a change in the state quantity of the cylinder interior gas attributable to compression in a compression stroke (minute piston work), and the heat generation quantity of a cool flame generated in PCCI combustion prior to autoignition (hot flame) (cool flame heat generation quantity Aqlto). A time when the cylinder interior temperature Tg reaches a predetermined autoignition start temperature Tig is estimated as an autoignition start time (Caig) of the premixed gas mixture related to PCCI combustion.

Abstract: The present apparatus calculates a mass ma (mass ratio ma/mf) of mixing-gas-forming cylinder interior gas, which is a portion of cylinder interior gas to be mixed with a forefront portion of injected fuel vapor having a mass of mf, on the basis of a predetermined empirical formula. Subsequently, under the assumption that heat exchange with the outside does not occur, the apparatus calculates an adiabatic gas mixture temperature Tmix of the gas mixture forefront portion on the basis of the heat quantity of the fuel vapor having a mass of mf and the heat quantity of the mixing-gas-forming cylinder interior gas having a mass of ma. Subsequently, in consideration of an amount of heat that the gas mixture forefront portion receives from peripheral cylinder interior gas mainly via a circumferential surface thereof, the apparatus estimates a final gas mixture temperature Tmixfin of the gas mixture forefront portion (i.e.

Abstract: A hydrogen storage alloy is provided which has an extremely low Co content, and can maintain the drain (power) performance (especially pulse discharge characteristics), activity (degree of activity), and life performance at high levels. The hydrogen storage alloy is manufactured by weighing and mixing every material for the hydrogen storage alloy so as to provide an alloy composition represented by the general formula MmNiaMnbAlcCod or MmNiaMnbAlcCodFee, and controlling the manufacturing method and manufacturing conditions so that both the a-axis length and the c-axis length of the crystal lattice are in a predetermined range. Although it is sufficient if the a-axis length of the crystal lattice is 499 pm or more and the c-axis length is 405 pm or more, by further specifying the a-axis length and c-axis length depending on the values of ABx, a hydrogen storage alloy having high durability can be provided.

Abstract: In an NOx discharge quantity estimation method for an internal combustion engine equipped with an EGR apparatus, the gas components (e.g., oxygen molecules and NOx) of intake gas taken into a combustion chamber are assumed to be uniformly distributed throughout the entire region of the combustion chamber. Under such assumption, the combustion chamber is divided into a combustion region (region B) and a non-combustion region (region A) by making use of the ratio of the “mass of oxygen consumed as a result of combustion” to the “total mass of oxygen taken in the combustion chamber.