Engine control system for hybrid vehicle

Claim 1

An engine control system for a hybrid vehicle having an internal combustion engine and an electric motor as driving force sources, for permitting stopping and starting of said engine in accordance with predetermined drive conditions, comprising: brake booster for receiving negative pressure supplied by an operation of said engine; pressure detector for detecting a pressure supplied to said brake booster; throttle-opening-state detector for detecting a throttle opening state; and engine-operation enable/disable determining device for determining whether or not to operate said engine when said engine is stopped, based on said throttle opening state detected by said throttle-opening-state detector and said pressure detected by said pressure detector, wherein said engine-operation enable/disable determining device: permits said engine to operate when said throttle opening state is other than completely closed; causes said engine to stop when said throttle opening state is completely closed and said pressure detected by said pressure detector is equal to or less than a predetermined negative pressure which is equal to or less than an atmospheric pressure; and permits said engine to operate when said throttle opening state is completely closed and said pressure detected by said pressure detector is closer to the atmospheric pressure than the predetermined negative pressure which is equal to or less than the atmospheric pressure.