Coast stop vehicle and control method thereof

A control method of a coast stop vehicle, in which a coast stop control for stopping an engine during travel of a vehicle is executed, the control method comprising:

• calculating a first deceleration, which is rotation deceleration of a rotation shaft on a driving wheel side of a frictional engagement element provided between the engine and a driving wheel;
• detecting an engine rotation speed;
• calculating a second deceleration, which is engine rotation deceleration;
• and
• controlling an engagement state of the frictional engagement element such that a decrease of the engine rotation speed is suppressed based on the first deceleration and the second deceleration, while the coast stop control is executed,
• wherein the frictional engagement element is released if the engine rotation speed is smaller than a first predetermined speed at which the engine is re-startable by re-injection of fuel, and the second deceleration is larger than the first deceleration, and
• wherein the frictional engagement element is engaged if the engine rotation speed is smaller than the first predetermined speed, and the second deceleration is equal to or less than the first deceleration.

A coast stop vehicle which executes a coast stop control for stopping an engine during travel of the vehicle, comprising:

• a frictional engagement element provided between the engine and a driving wheel;
• first deceleration calculating means for calculating a first deceleration, which is rotation deceleration of a rotation shaft on a driving wheel side of the frictional engagement element;
• an engine rotation speed detecting means for detecting an engine rotation speed;
• a second deceleration calculating means for calculating a second deceleration, which is engine rotation deceleration;
• and
• engagement-state control means for controlling an engagement state of the frictional engagement element such that a decrease of the engine rotation speed is suppressed based on the first deceleration and the second deceleration while the coast stop control is executed,
• wherein the engagement-state control means releases the frictional engagement element if the engine rotation speed is smaller than a first predetermined speed at which the engine is re-startable by re-injection of fuel, and the second deceleration is larger than the first deceleration, and
• wherein the engagement-state control means engages the frictional engagement element if the engine rotation speed is smaller than the first predetermined speed, and the second deceleration is equal to or less than the first deceleration.