Patent claim: An engine system 200 comprising an engine unit EU that includes an engine 10 and a rotation driver 14 an intake passage 22 arranged to lead air to the engine 10 a flow rate adjuster TV IV configured to adjust a flow rate of air in the intake passage 22 and a controller 6 configured to control the engine unit EU and the flow rate adjuster TV IV wherein the engine 10 includes a cylinder 31 a fuel injection device 19 arranged to inject fuel into the intake passage 22 at a downstream of the flow rate adjuster TV IV an ignition device 18 configured to ignite a fuelair mixture in a combustion chamber 31a and a valve driver 17 configured to respectively drive an intake valve 15 for opening and closing an intake port 21 and an exhaust valve 16 for opening and closing an exhaust port 23 the rotation driver 14 configured to drive a rotation of a crankshaft 13 of the engine 10 in a forward direction R1 or a reverse direction R2 the valve driver 17 configured to drive the intake valve 15 such that the intake port 21 is opened when a crank angle is in a predetermined startup intake range A21A22 during the rotation of the crankshaft 13 in the reverse direction R2 and the controller 6 configured to control the flow rate adjuster TV IV such that air flows in the intake passage 22 and the combustion chamber 31a and control the fuel injection device 19 and the ignition device 18 such that the crankshaft 13 is rotated in the forward direction R1 by inertia without combustion of the fuelair mixture in the combustion chamber 31a at a time of stop operation of the engine 10 and control the rotation driver 14 such that the crankshaft 13 is rotated in the reverse direction R2 until the crank angle goes over the startup intake range A21A22 and reaches a predetermined startup ignition range A31 control the fuel injection device 19 such that the fuelair mixture is introduced into the combustion chamber 31a through the intake port 21 when the crank angle is in the startup intake range A21A22 and control the ignition device 18 such that the fuelair mixture in the combustion chamber 31a is ignited when the crank angle is in the startup ignition range A31 at a time of startup operation of the engine 10.

Related passage: Thus if the piston 13 of the stoppedstate expansionstroke cylinder can be stopped within a given range R slightly on the side of BDC relative to a position corresponding a crank angle after compression TDC of 90CA for example at a position where the crank angle after compression TDC is in a range of 100CA to 120CA a given volume of air will be ensured in the stoppedstate compressionstroke cylinder to obtain combustion energy from the initial combustion to an extent allowing the crankshaft 3 to be reversely rotated by a small angle.In addition a large volume of air can be ensured in the stoppedstate expansionstroke cylinder so that combustion energy for normally rotating the crankshaft 3 can be sufficiently generated toreliably restart the engine.The above range R will hereinafter be referred to as adequate stop range R.From this point of view the ECU 2 is designed to perform an automatic engine stop control process for example of adjusting an opening degree of the throttle valve 23 so as to stop the piston 13 within the adequate stop range R.