Malfunction detecting device for internal combustion engine

摘要

A malfunction detecting device for an internal combustion engine is mounted on a vehicle and includes an engine and a control unit. The engine is a multi-cylinder engine and is a bi fuel-enabled engine which is capable of switching plural kinds of fuels including a gas fuel and which can use bifuel. The control unit detects, in case of detecting a malfunction with respect to an imbalance of an air fuel ratio among the cylinders at a time of an operation based on the gas fuel, the malfunction based on variation of pressure pulsations of the gas fuel due to a fuel injection.

主权项

1. A malfunction detecting device for an internal combustion engine, comprising:
an engine which includes plural cylinders and which is capable of switching plural kinds of fuels including a gas fuel and a liquid fuel; a gas pressure sensor provided on a passage or in a pipe for supplying the gas fuel to each of the cylinders; an air-fuel ratio sensor provided on an exhaust passage connected to the engine; an injection quantity estimation unit configured to estimate, when there is a request to switch from an operation by the gas fuel to an operation by the liquid fuel and the air-fuel ratio sensor is not activated, an injection quantity of each of the cylinders at a time of the operation by the gas fuel based on a decreasing degree of gas pressure detected by the gas pressure sensor; a malfunction detection unit configured to detect a malfunction with respect to an imbalance of air fuel ratios among the cylinders based on the injection quantity of each of the cylinders estimated by the injection quantity estimation unit; and a switching unit configured to switch from the operation by the gas fuel to the operation by the liquid fuel after detecting the malfunction by the malfunction detection unit.