US Patent 7444220 Power output apparatus for hybrid vehicle

Under a switchover operation of an EGR valve from OFF to ON or from ON to OFF, the control procedure of the invention keeps an engine power demand Pe*, which is to be output from an engine and is set corresponding to a torque demand Tr* to be output to a drive shaft, unchanged to a previous level (Previous Pe*) set immediately before the switchover operation of the EGR valve (step S120). A torque command Tm2* of a motor MG2 is set to ensure output of the torque demand Tr* to the drive shaft (step S126). The engine and motors MG1 and MG2 are then driven and controlled with preset target values and torque commands. Such control desirably prevents a variation in load of the engine simultaneous with the switchover operation of the EGR valve and accordingly ensures favorable emission control performance, while attaining output of the torque demand Tr* to the drive shaft.