Control apparatus for hybrid vehicle

摘要

A control apparatus is applied to a hybrid vehicle including an internal combustion engine that is capable of changing over its combustion state between lean combustion and stoichiometric combustion. The control apparatus executes noise suppression control by limiting the operating point of the internal combustion engine to be upon a noise suppression line for lean combustion or to be upon a noise suppression line for stoichiometric combustion, so that the noise generated by a power transmission mechanism is suppressed. When changing over from lean combustion to stoichiometric combustion during execution of noise suppression control, the control apparatus of the present invention changes the air/fuel ratio after changing the operating point of the internal combustion engine from one point to a point that is more toward the lower torque side of the noise suppression line.

主权项

1. A control apparatus applied to a hybrid vehicle that comprises, as power sources for propulsion, an internal combustion engine that is capable of changing its combustion state while operating between lean combustion and stoichiometric combustion and a motor-generator, and in which engine torque of the internal combustion engine and motor torque of the motor-generator are outputted to a drive wheel via a power transmission mechanism that includes a gear group, comprising:
an electronic control unit (ECU) programmed to: change over the combustion state of the internal combustion engine between the lean combustion and the stoichiometric combustion by performing air/fuel ratio change control in which both a fuel amount and an air amount supplied to the internal combustion engine are changed; execute noise suppression control in which an operating point of the internal combustion engine, as defined by engine rotational speed and engine torque, is limited to be upon one of predetermined noise suppression lines that are based upon advanced testing and stored in a program readable by the ECU, and that are set to correspond both to the lean combustion and to the stoichiometric combustion, so that noise generated by the power transmission mechanism is suppressed; and change over the operating point of the internal combustion engine toward the side of lower torque than the one of the noise suppression lines before the ECU executes the air/fuel ratio change control, when the ECU changes over the combustion state of the internal combustion engine from the lean combustion to the stoichiometric combustion during execution of the noise suppression control.