Toyota Jidosha Kabushiki Kaisha

Kenji Inoshita

Norihisa Nakagawa

Shogo Tanaka

Masanao Idogawa

Shuntaro Okazaki

Yuji Miyoshi

Koji Miwa

Takeru Yoshida

Isao Chinzei

Kazuya Suzuki

Takahiro Tsukagoshi

Koichi Kitaura

Kaoru Otsuka

An engine controller performs air-fuel ratio sub-feedback control in which a target air-fuel ratio is switched from a rich air-fuel ratio to a lean air-fuel ratio when a rear air-fuel ratio detected by an air-fuel ratio sensor becomes less than or equal to a rich determination value, and the target air-fuel ratio is switched from the lean air-fuel ratio to the rich air-fuel ratio when the rear air-fuel ratio becomes greater than or equal to a lean determination value. To perform the sub-feedback control, the controller variably sets the lean determination value to a value indicating a leaner air-fuel ratio when an amount of overshoot of the rear air-fuel ratio to a richer value than a stoichiometric air-fuel ratio after switching the target air-fuel ratio from the rich air-fuel ratio to the lean air-fuel ratio is relatively large than when the amount of overshoot is relatively small.

Engine controller

An engine device includes: an engine; and a control device that executes a return rich control that controls the engine so that an air-fuel ratio becomes rich over a predetermined period after the engine returns from the fuel cut. When the engine is intermittently stopped during the execution of the return rich control, the return rich control is executed for a period shorter than the predetermined period after the engine is restarted. Thus, when the engine is intermittently stopped during the execution of the return rich control and the engine is restarted thereafter, it is possible to suppress a total period of the return rich control from becoming long. As a result, it is possible to suppress an increase in the amount of hydrocarbons in the exhaust gas and suppress deterioration of emissions.

Engine device

The controller includes a fuel amount control unit adjusting amount of fuel supplied to a cylinder through feedback control with an air-fuel ratio deviation as input, a target air-fuel ratio adjustment unit alternately repeating a lean period process and a rich period process, and a learning value correction unit updating a learning value to compensate for a steady deviation in an air-fuel ratio. If an absolute value of an oxygen amount deviation is less than a determination value, the learning value update unit updates a learning value only when one of the lean period process and the rich period process is switched to the other one. If the absolute value of the oxygen amount deviation is greater than or equal to the determination value, the learning value is updated both when one of the processes is switched to the other one and when the switching is reversed.

Controller for internal combustion engine and method for controlling internal combustion engine

The exhaust purification system of an internal combustion engine has: exhaust purification catalystsarranged in an exhaust passage and able to store oxygen; and a control devicefor calculating an EGR rate of intake gas supplied to combustion chambersand for controlling an air-fuel ratio of the exhaust gas flowing into the catalysts. The control device alternately switches the air-fuel ratio between a rich air-fuel ratio and a lean air-fuel ratio, and controls the air-fuel ratio so that the air-fuel ratio is switched from the lean air-fuel ratio to the rich air-fuel ratio when the oxygen storage amount of the catalyst is greater, when the calculated EGR rate is relatively high, compared to when it is relatively low.

Exhaust purification system of internal combustion engine

A vehicle includes an internal combustion engine including an exhaust passage, a catalyst provided in the exhaust passage, and an electronic control unit. When the engine stop condition is established, the electronic control unit stops fuel injection and increases a catalyst inflow oxygen amount that is an amount of oxygen flowing into the catalyst by a specified oxygen increase amount. The engine stop condition is a condition for stopping operation of the internal combustion engine. The specified oxygen increase amount is larger than an increased part of the catalyst inflow oxygen amount that is increased by the stop of the fuel injection.

Vehicle and control method for vehicle

An exhaust purification system of an internal combustion engine comprises an air-fuel ratio control device controlling an air-fuel ratio of the inflowing exhaust gas to a target air-fuel ratio. If a first judged condition wherein an estimated amount of change of an oxygen storage amount of the catalyst when the target air-fuel ratio is maintained at the first set air-fuel ratio is equal to or greater than a first reference amount, and a second judged condition wherein a difference of an air-fuel ratio detected by the upstream side air-fuel ratio sensor and a stoichiometric air-fuel ratio is equal to or greater than a difference of a second judged air-fuel ratio and a stoichiometric air-fuel ratio are satisfied, the air-fuel ratio control device switches the target air-fuel ratio from the first set air-fuel ratio to the second set air-fuel ratio when the first judged condition and second judged condition are satisfied.

An exhaust purification system comprises a catalystan upstream side air-fuel ratio sensora downstream side air-fuel ratio sensorand an air-fuel ratio control device. The air-fuel ratio control device alternately switches a target air-fuel ratio between a rich set air-fuel ratio and a lean set air-fuel ratio, calculates an oxygen storage amount and an oxygen discharge amount, updates a learning value, and corrects an air-fuel ratio-related parameter based on the learning value. The air-fuel ratio control device changes a condition for switching the target air-fuel, stores the learning value at the time when the operating state of the internal combustion engine changes from the first state to the second state as a first state value, and updates the learning value to the first state value when the operating state of the internal combustion engine returns from the second state to the first state.

An exhaust purification system comprises an air-fuel ratio control device. If the air-fuel ratio detected by the downstream side air-fuel ratio sensorreaches a second judged air-fuel ratio, the air-fuel ratio control device sets the target air-fuel ratio to a third set air-fuel ratio when the air-fuel ratio reaches the second judged air-fuel ratio, and switch the target air-fuel ratio from the third set air-fuel ratio to the second set air-fuel ratio when the air-fuel ratio becomes a value at the stoichiometric air-fuel ratio side from the second judged air-fuel ratio. The first set air-fuel ratio, the first judged air-fuel ratio and the second judged air-fuel ratio are an air-fuel ratio in the first region. The second set air-fuel ratio and the third set air-fuel ratio are an air-fuel ratio in a second region at an opposite side from the first region.

A control device for an internal combustion engine is provided with a target air-fuel ratio setting part including a first setting control part performing normal control alternately switching a target air-fuel ratio between a predetermined first lean air-fuel ratio and a predetermined first rich air-fuel ratio and a second setting control part performing control for restoration of the storage amount stopping normal control and increasing the oxygen storage amount of a second catalyst when an output air-fuel ratio of a third air-fuel ratio sensor becomes a predetermined rich judgment air-fuel ratio or less. Further, the second setting control part is configured to set the target air-fuel ratio to a predetermined second lean air-fuel ratio larger than the first lean air-fuel ratio at the time of start of the control for restoration of the storage amount and set the target air-fuel ratio to a predetermined third lean air-fuel ratio smaller than the second lean air-fuel ratio after an exhaust with a larger air-fuel ratio than the stoichiometric air-fuel ratio flows out from the first catalyst in the time period of setting the target air-fuel ratio to the second lean air-fuel ratio.

Growing community of inventors

Okazaki, Japan

Kenji Inoshita