Air/fuel ratio control device for internal combustion engine

Abstract

The invention discloses an air-fuel ratio control device for an internal combustion engine, which can freely change the oxygen absorption amplitude without changing the period and amplitude of the air-fuel ratio vibration that emphasizes the air-fuel ratio feedback performance and torque variation, so as to adapt to or diagnose catalyst degradation. Equipped with: According to the output value (V1) of the upstream air-fuel ratio sensor (13) and the specified control constant, adjust the air-fuel ratio of the main body (1) of the feeder, and make the air-fuel ratio periodically vibrate in the rich direction and the lean direction. An air-fuel ratio feedback control unit (201); and operate the control constant according to the oxygen absorption amount of the catalyst, so that the average air-fuel ratio obtained after averaging the periodically vibrating air-fuel ratio vibrates toward a rich direction and a lean direction. Vibration unit (203).

Description

technical field [0001] The present invention relates to an air-fuel ratio control device for an internal combustion engine mounted on a vehicle, and more particularly to an air-fuel ratio control device for an internal combustion engine provided with an air-fuel ratio feedback control unit for periodically vibrating the air-fuel ratio supplied to the internal combustion engine in a rich direction and a lean direction. Background technique [0002] On the exhaust passage of the internal combustion engine, it is generally installed to simultaneously purify the harmful components HC, CO, and NO in the exhaust gas. x The three-way catalyst (hereinafter referred to as "catalyst"). In this catalyst, the harmful components HC, CO, NO near the theoretical air-fuel ratio x Both have high purification rates. Therefore, in the air-fuel ratio control device of the internal combustion engine, the O 2 The sensor adjusts the fuel injection amount and performs feedback control on the air...

AI Technical Summary

Problems solved by technology

[0014] Existing air-fuel ratio control devices for internal combustion engines, such as those described in Patent Document 1, have the problem that the amplitude or cycle of air-fuel ratio vibration needs to be greatly changed with the maximum oxygen absorption amount, so the air-fuel ratio feedback performance and Torque fluctuations have a large influence, making the air-fuel ratio control performance poor

[0015] Furthermore, when the amplitude or period of the air-fuel ratio vibration becomes large, there are problems in that the performance of converging to a steady state when disturbance occurs is poor, and the exhaust performance during acceleration or deceleration is poor.

[0016] Torque fluctuations occur due to changes in the air-fuel ratio, and when the amplitude or period changes greatly, the drivability is poor and the marketability is reduced. Therefore, it is difficult to combine the conditions for vibration processing of the oxygen absorption amount with the setting conditions that emphasize feedback performance and those that emphasize torque. Tasks set separately from setting conditions

[0017] In order to adapt to the exhaust gas regulations of various settings in the world, it is necessary to change the catalyst according to the regulations of each country and region, and make various changes in the maximum oxygen absorption. Therefore, it is necessary to set the amplitude or period of air-fuel ratio vibration for each catalyst, and there is an appropriate Topics with high cost

In addition, there are various exhaust gas regulations for diagnosing catalyst deterioration, and there is a problem of adapting the amplitude and cycle of air-fuel ratio vibration according to the regulations of each country and region.

[0018] In addition, in recent years, the awareness of the global environment has increased, so regulations on exhaust gas have been strengthened, and in order to detect relatively slight catalyst degradation (decrease in the maximum oxygen absorption capacity), it is required to set the period or amplitude of the air-fuel ratio vibration to be large. Problems leading to various performance deterioration trends such as poor air-fuel ratio feedback performance and increased torque fluctuations

[0019] Recently, the heat resistance of substances capable of absorbing oxygen is increasing year by year, and the amount of addition to the catalyst may increase. Therefore, the maximum oxygen absorption capacity increases. It is required to set the period or amplitude of the air-fuel ratio vibration as large as possible, so there are problems that may cause Issues related to various performance deterioration trends such as poor air-fuel ratio feedback performance and increased torque fluctuations

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