Abstract: When an engine power demand Pe* is not greater than a maximum power Pemax, the drive control sets a target rotation speed Ne* and a target torque Te* of an engine according to a reference operation curve obtained in air-fuel ratio control with a stoichiometric air-fuel ratio (step S125). When the engine power demand Pe* exceeds the maximum power Pemax, on the other hand, upon failure of a preset fuel increase prohibition condition, the drive control sets the target rotation speed Ne* to a maximum rotation speed Nemax (step S140) and sets a target air-fuel ratio used for the air-fuel ratio control of the engine to a rich air-fuel ratio based on the engine power demand Pe* (step S150).

Abstract: The engine stop control of the invention uses a correction factor k based on an ambient temperature Tdp in the vicinity of a delivery pipe to set an engine-stop criterion fuel pressure Pref as a fuel pressure of ensuring the sufficient startability of an engine and preventing the vapor generation. The engine stop control stops the operation of the engine after a decrease in fuel pressure Pf in the delivery pipe below the engine-stop criterion fuel pressure Pref. This arrangement effectively prevents the fuel oil-tight leaked from fuel injection valves from being accumulated in cylinders of the engine and thus restrains the poor emission, which may be caused by direct discharge of the fuel accumulated in the cylinders at a restart of the engine. The engine stop control of the invention also reduces the frequency of operation of a relief valve, which works to prevent an excessive increase in fuel pressure Pf in the delivery pipe, thus enhancing the durability of the relief valve.

Abstract: In a vehicle incorporating an internal combustion engine having in-cylinder injectors and intake manifold injectors and performing engine intermittent operation control, at the end of vehicle operation, the fuel pressure is decreased in both a high-pressure delivery pipe and a low-pressure delivery pipe by actuation (opening) of an electromagnetic relief valve and by stop of operation of a low-pressure fuel pump. This prevents deterioration in emission performance at the next engine start attributable to fuel leakage due to degradation in oil tightness of the injectors during the operation stop period. When the engine is temporarily stopped by engine intermittent operation control, while the low-pressure fuel pump is stopped, actuation (opening) of the electromagnetic relief valve is prohibited. At the engine restart after temporary stop, the fuel in the high-pressure delivery pipe having its pressure secured at a certain level is injected to quickly start the engine.

Abstract: A low-pressure delivery pipe provided with intake manifold injectors, a fuel pressure regulator, a high-pressure fuel pump, a high-pressure delivery pipe provided with in-cylinder injectors, and an electromagnetic relief valve are connected in series at the downstream of a low-pressure fuel pump that discharges a fuel within a fuel tank at a prescribed pressure. Since the low-pressure delivery pipe is arranged downstream of the low-pressure fuel pump, the fuel pressure within the low-pressure delivery pipe is lowered upon stop of vehicle operation, in response to stop of the low-pressure fuel pump. The fuel pressure within the high-pressure delivery pipe is also lowered in response to stop of the low-pressure fuel pump, by opening the electromagnetic relief valve upon stop of vehicle operation. Thus, oil tightness of the injectors during the stop of vehicle operation is ensured.

Abstract: In a vehicle incorporating an internal combustion engine having in-cylinder injectors and intake manifold injectors and performing engine intermittent operation control, at the end of vehicle operation, the fuel pressure is decreased in both a high-pressure delivery pipe and a low-pressure delivery pipe by actuation (opening) of an electromagnetic relief valve and by stop of operation of a low-pressure fuel pump. This prevents deterioration in emission performance at the next engine start attributable to fuel leakage due to degradation in oil tightness of the injectors during the operation stop period. When the engine is temporarily stopped by engine intermittent operation control, while the low-pressure fuel pump is stopped, actuation (opening) of the electromagnetic relief valve is prohibited. At the engine restart after temporary stop, the fuel in the high-pressure delivery pipe having its pressure secured at a certain level is injected to quickly start the engine.

Abstract: In a vehicle incorporating an internal combustion engine having in-cylinder injectors and intake manifold injectors and performing engine intermittent operation control, at the end of vehicle operation, the fuel pressure is decreased in both a high-pressure delivery pipe and a low-pressure delivery pipe by actuation (opening) of an electromagnetic relief valve and by stop of operation of a low-pressure fuel pump. This prevents deterioration in emission performance at the next engine start attributable to fuel leakage due to degradation in oil tightness of the injectors during the operation stop period. When the engine is temporarily stopped by engine intermittent operation control, while the low-pressure fuel pump is stopped, actuation (opening) of the electromagnetic relief valve is prohibited. At the engine restart after temporary stop, the fuel in the high-pressure delivery pipe having its pressure secured at a certain level is injected to quickly start the engine.

Abstract: The start control procedure of the invention lags an open-close timing VVT of an intake valve, restricts a throttle opening TH of a throttle valve, and starts cranking an engine with a lower torque Tlow. When a pressure Pf of a fuel supplied to in-cylinder fuel injection valves reaches or exceeds a preset reference value, which is greater than a sum of an in-cylinder compression pressure Pin and a closed valve position-retaining pressure Pcv of the in-cylinder fuel injection valves, the start control procedure cranks the engine with a standard cranking torque Tset. The start control procedure then starts advance of the open-close timing VVT of the intake valve, cancels the restriction of the throttle opening TH, and starts fuel injection from the in-cylinder fuel injection valves.

Abstract: A low-pressure delivery pipe provided with intake manifold injectors, a fuel pressure regulator, a high-pressure fuel pump, a high-pressure delivery pipe provided with in-cylinder injectors, and an electromagnetic relief valve are connected in series at the downstream of a low-pressure fuel pump that discharges a fuel within a fuel tank at a prescribed pressure. Since the low-pressure delivery pipe is arranged downstream of the low-pressure fuel pump, the fuel pressure within the low-pressure delivery pipe is lowered upon stop of vehicle operation, in response to stop of the low-pressure fuel pump. The fuel pressure within the high-pressure delivery pipe is also lowered in response to stop of the low-pressure fuel pump, by opening the electromagnetic relief valve upon stop of vehicle operation. Thus, oil tightness of the injectors during the stop of vehicle operation is ensured.

Abstract: A low-pressure delivery pipe provided with intake manifold injectors, a fuel pressure regulator, a high-pressure fuel pump, a high-pressure delivery pipe provided with in-cylinder injectors, and an electromagnetic relief valve are connected in series at the downstream of a low-pressure fuel pump that discharges a fuel within a fuel tank at a prescribed pressure. Since the low-pressure delivery pipe is arranged downstream of the low-pressure fuel pump, the fuel pressure within the low-pressure delivery pipe is lowered upon stop of vehicle operation, in response to stop of the low-pressure fuel pump. The fuel pressure within the high-pressure delivery pipe is also lowered in response to stop of the low-pressure fuel pump, by opening the electromagnetic relief valve upon stop of vehicle operation. Thus, oil tightness of the injectors during the stop of vehicle operation is ensured.

Abstract: A low-pressure delivery pipe provided with intake manifold injectors, a fuel pressure regulator, a high-pressure fuel pump, a high-pressure delivery pipe provided with in-cylinder injectors, and an electromagnetic relief valve are connected in series at the downstream of a low-pressure fuel pump that discharges a fuel within a fuel tank at a prescribed pressure. Since the low-pressure delivery pipe is arranged downstream of the low-pressure fuel pump, the fuel pressure within the low-pressure delivery pipe is lowered upon stop of vehicle operation, in response to stop of the low-pressure fuel pump. The fuel pressure within the high-pressure delivery pipe is also lowered in response to stop of the low-pressure fuel pump, by opening the electromagnetic relief valve upon stop of vehicle operation. Thus, oil tightness of the injectors during the stop of vehicle operation is ensured.

Abstract: The technique of the invention determines whether input data for driving and controlling a cooling fan have any abnormality (steps S100 and S110), sets an actual drive level F* of the cooling fan to a high level (Hi) in the event of detection of any abnormality (step S130), and controls a fan motor to drive the cooling fan at the set drive level F* (step S140). This arrangement effectively prevents a temperature rise to an abnormally high level in any of an engine and motors even in the event of any abnormality arising in the input data.

Abstract: In hybrid vehicle, when the shift position SP is set to the S position at which a driver is allowed to select any one of the shift positions SP1 to SP6, and it is determined that warm-up of a purifying device has not been completed, the target air-fuel ratio AF* is set based on the S position/low coolant temperature-time target air-fuel ratio setting map. The air-fuel ratio AF* set based on the S position/low coolant temperature-time target air-fuel ratio setting map tends to be richer than the target air-fuel ratio AF* set based on any one of the normal-time target air-fuel ratio setting map and the D position/low coolant temperature-time target air-fuel ratio setting map that are used when the D position is selected.

Abstract: In a hybrid vehicle, when the shift position SP is set to the S position at which a driver is allowed to select any one of the shift positions SP1 to SP6, and it is determined that warm-up of a purifying device has not been completed, the target air-fuel ratio AF* is set based on the S position/low coolant temperature-time target air-fuel ratio setting map. The air-fuel ratio AF* set based on the S position/low coolant temperature-time target air-fuel ratio setting map tends to be richer than the target air-fuel ratio AF* set based on any one of the normal-time target air-fuel ratio setting map and the D position/low coolant temperature-time target air-fuel ratio setting map that are used when the D position is selected.

Abstract: The auto engine start control of the invention regulates a throttle valve to a restricted opening to reduce an air intake flow at an ordinary start of an engine (step S140). When the driver stamps on an accelerator pedal to raise an engine power demand Pe* to or above a preset threshold value Pref, the auto engine start control regulates the throttle valve to a standard opening to ensure the air intake flow corresponding to the engine power demand Pe* (step S150) and thereby cranks the engine. This arrangement desirably dampens potential vibration induced by ignition at the ordinary start of the engine, while ensuring prompt output of the required driving force from the engine under the condition of the higher engine power demand Pe*.

Abstract: In a hybrid vehicle of the invention, in the event of specification that an exhaust treatment catalyst is in a preset adequate state at step S112, combustion control of an engine starts after a decrease of an intake pipe pressure P to a preset reference negative pressure Pref and reduction of an intake air flow into a cylinder of the engine by engine motoring. In the event of specification that the exhaust treatment catalyst is not in the preset adequate state but in an inadequate state at step S112, on the other hand, the combustion control of the engine immediately starts, prior to the decrease of the intake pipe pressure P to the preset reference negative pressure Pref.

Abstract: In a vehicle incorporating an internal combustion engine having in-cylinder injectors and intake manifold injectors and performing engine intermittent operation control, at the end of vehicle operation, the fuel pressure is decreased in both a high-pressure delivery pipe and a low-pressure delivery pipe by actuation (opening) of an electromagnetic relief valve and by stop of operation of a low-pressure fuel pump. This prevents deterioration in emission performance at the next engine start attributable to fuel leakage due to degradation in oil tightness of the injectors during the operation stop period. When the engine is temporarily stopped by engine intermittent operation control, while the low-pressure fuel pump is stopped, actuation (opening) of the electromagnetic relief valve is prohibited. At the engine restart after temporary stop, the fuel in the high-pressure delivery pipe having its pressure secured at a certain level is injected to quickly start the engine.

Abstract: In an engine 5 including an in-cylinder injector, the valve timing of an intake valve is retarded by VVT (Variable Valve Timing) controlled by an engine ECU to decompress in a combustion chamber at engine startup. In accordance with a configuration in which the valve timing of intake valve is advanced in a stepped manner from an initial set value, fuel injection from in-cylinder injector is inhibited during the time when the advance is equal to or below a predetermined standard value, and fuel injection from in-cylinder injector is allowed when exceeding the predetermined standard value, whereby degradation in the exhaust emission level in accordance with start time decompression control can be suppressed.

Abstract: The start control procedure of the invention lags an open-close timing VVT of an intake valve, restricts a throttle opening TH of a throttle valve, and starts cranking an engine with a lower torque Tlow. When a pressure Pf of a fuel supplied to in-cylinder fuel injection valves reaches or exceeds a preset reference value, which is greater than a sum of an in-cylinder compression pressure Pin and a closed valve position-retaining pressure Pcv of the in-cylinder fuel injection valves, the start control procedure cranks the engine with a standard cranking torque Tset. The start control procedure then starts advance of the open-close timing VVT of the intake valve, cancels the restriction of the throttle opening TH, and starts fuel injection from the in-cylinder fuel injection valves.

Abstract: A low-pressure delivery pipe provided with intake manifold injectors, a fuel pressure regulator, a high-pressure fuel pump, a high-pressure delivery pipe provided with in-cylinder injectors, and an electromagnetic relief valve are connected in series at the downstream of a low-pressure fuel pump that discharges a fuel within a fuel tank at a prescribed pressure. Since the low-pressure delivery pipe is arranged downstream of the low-pressure fuel pump, the fuel pressure within the low-pressure delivery pipe is lowered upon stop of vehicle operation, in response to stop of the low-pressure fuel pump. The fuel pressure within the high-pressure delivery pipe is also lowered in response to stop of the low-pressure fuel pump, by opening the electromagnetic relief valve upon stop of vehicle operation. Thus, oil tightness of the injectors during the stop of vehicle operation is ensured.

Abstract: The auto engine start control of the invention regulates a throttle valve to a restricted opening to reduce an air intake flow at an ordinary start of an engine (step S140). When the driver stamps on an accelerator pedal to raise an engine power demand Pe* to or above a preset threshold value Pref, the auto engine start control regulates the throttle valve to a standard opening to ensure the air intake flow corresponding to the engine power demand Pe* (step S150) and thereby cranks the engine. This arrangement desirably dampens potential vibration induced by ignition at the ordinary start of the engine, while ensuring prompt output of the required driving force from the engine under the condition of the higher engine power demand Pe*.