START CONTROLAPPARATUS FOR INTERNAL COMBUSTION ENGINE

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a start control apparatus for an internal combustion engine including a fuel injection valve provided in an intake port, which starts the internal combustion engine by combusting fuel in a cylinder that is stopped in an intake stroke. 2. Description of the Related Art

[0002] Japanese Patent Application Publication No. 2004-36561 (JP-A-2004-36561) describes an automatic stop-start apparatus for an in-cylinder injection internal combustion engine. When a predetermined stop condition is fulfilled, the automatic stop-start apparatus executes an idling stop control that automatically stops the internal combustion engine. When a predetermined restart condition is fulfilled, the automatic stop-start apparatus executes a control so that fuel is injected into a cylinder in an intake stroke.

[0003] In general, intake air amount, which is initially taken into an intake stroke cylinder (i.e., a cylinder in which a piston is stopped in an intake stroke when an internal combustion engine is stopped) at the time of start of the engine, varies depending on a position at which the piston is stopped. That is, the position at which the piston is stopped becomes closer to a bottom dead center, the amount of intake air that is initially taken into the intake stroke cylinder becomes smaller. Therefore, when the above-described automatic stop-start apparatus starts the internal combustion engine by injecting fuel into the intake stroke cylinder at the time of start of the internal combustion engine, if the piston is stopped at a position near the bottom dead center, the amount of intake air taken into the intake stroke cylinder is small, and therefore, combustion may be unstable, and a misfire may occur. In a port injection internal combustion engine in which fuel is injected into an intake port, if the piston in the intake stroke cylinder is

stopped at a position near the bottom dead center, a period in which the first intake stroke is performed is short. Therefore, fuel may not be sufficiently supplied to the intake stroke cylinder, combustion may be unstable, and a misfire may occur. Further, if a misfire occurs at the time of start of the internal combustion engine, the time required to start the internal combustion engine may increase.

SUMMARY OF THE INVENTION

[0004] The invention provides a start control apparatus for an internal combustion engine, which improves combustion in a cylinder in which a piston is stopped in an intake stroke at a time of start of the internal combustion engine, and thus, promptly starts the internal combustion engine.

[0005] A first aspect of the invention relates to a start control apparatus for an internal combustion engine that includes cylinders, and fuel injection valves provided in intake ports for the respective cylinders. The start control apparatus starts the internal combustion engine by supplying fuel to an intake stroke cylinder in which a piston is stopped in an intake stroke, using the fuel injection valve for the intake stroke cylinder, when a predetermined start condition is fulfilled. The start control apparatus includes flow speed changing means, position determination means, and control means. The flow speed changing means changes a flow speed of intake air in the intake port for the intake stτoke cylinder. The position determination means determines whether the piston in the intake stroke cylinder is stopped in a predetermined crank angle range set to correspond to a latter stage of the intake stroke, when the predetermined start condition is fulfilled. The control means controls the flow speed changing means to increase the flow speed of the intake air in the intake port for the intake stroke cylinder, and then, starts the internal combustion engine, when the position determination means determines that the piston in the intake stroke cylinder is stopped in the predetermined crank angle range.

[0006] According to the above-described aspect, when the piston in the intake stroke cylinder is stopped in the predetermined crank angle range set to correspond to, for

example, the latter stage of the intake stroke, that is, the predetermined crank angle range set to be near the bottom dead center, the flow speed of the intake air in the intake port for the intake stroke cylinder is increased at the time of start of the internal combustion engine. Therefore, the fuel is promptly supplied to the intake stroke cylinder together with the intake air. Also, by increasing the flow speed of the intake aii, it is possible to increase the strength of an airflow formed in the intake stroke cylinder, such as a swirl flow or a tumble flow. Therefore, an appropriate amount of the fuel is supplied to the intake stroke cylinder, and combustion in the intake stroke cylinder is improved, at the time of start of the internal combustion engine. Thus, the internal combustion engine is promptly started.

[0007] In the above-described aspect, the flow speed changing means may include a valve provided in the intake port for each of the cylinders at a position upstream of the fuel injection valve. A position of the valve is switchable between a closing position in which the valve decreases a flow passage sectional area of the intake port, and an opening position in which the valve fully opens the intake port. If the position determination means determines that the piston in the intake stroke cylinder is stopped in the predetermined crank angle range when the predetermined start condition is fulfilled, the control means may switch the position of the valve provided in the intake port for the intake stroke cylinder to the closing position, and then, may start the internal combustion engine. Thus, by decreasing the flow passage sectional area of the intake port by switching the position of the valve to the closing position, the flow speed of the intake air ^• in the intake port is increased.

[0008] In the above-described aspect, the flow speed changing means may include air supply means for supplying air to the intake stroke cylinder when the internal combustion engine is stopped. If the position determination means determines that the piston in the intake stroke cylinder is stopped in the predetermined crank angle. range when the predetermined start condition is fulfilled, the control means may operate the air supply means, and then, may start the internal combustion engine. Thus, by supplying air in advance to the intake stroke cylinder using the air supply means before the internal

combustion engine is started, an appropriate amount of air is supplied to the intake stroke cylinder. Also, because a airflow into the intake stroke cylinder is forcibly generated by supplying air to the intake stroke cylinder using the air supply means, the fuel is introduced into the intake stroke cylinder by the airflow. Further, at the time of start of the internal combustion engine, air is supplied to the intake stroke cylinder using the air supply means, in addition to the air taken into the intake stroke cylinder by moving the piston downward. Therefore, the flow speed of the intake air in the intake port is increased.

[0009] In the above-described aspect, the air supply means may include a pump that supplies air into an intake passage. The internal combustion engine may include a supercharger that is driven by an electric motor. The air supply means may be the supercharger. Thus, air may be supplied to the intake stroke cylinder by supplying air into the intake passage using the pump, or air may be supplied to the intake stroke cylinder by driving the supercharger using the electric motor. [0010] In the above-described aspect, the start control apparatus may further include a variable valve operating mechanism. A state of an exhaust valve for each of the cylinders of the internal combustion engine is switchable to an open state by the variable valve operating mechanism when the internal combustion engine is stopped

When the predetermined start condition is fulfilled, the control means may control the variable valve operating mechanism to switch the state of the exhaust valve for the intake stroke cylinder to the open state, before operating the air supply means. Thus, by opening the exhaust valve for the intake stroke cylinder before the air supply means is operated, the strength of the airflow into the intake stroke cylinder is increased.

Therefore, the fuel is introduced into the intake stroke cylinder more promptly. [0011] In the above-described aspect, the start control apparatus may further include a variable valve operating mechanism. A state of an exhaust valve for each of the cylinders of the internal combustion engine is switchable to an open state when the internal combustion engine is stopped. The flow speed changing means may include a suction pump that sucks air from an exhaust passage for the internal combustion engine.

If the position determination means determines that the piston in the intake stroke cylinder is stopped in the predetermined crank angle range when the predetermined start condition is fulfilled, the control means may control the variable valve operating mechanism to switch the state of the exhaust valve for the intake stroke cylinder to the open state, and then, may operate the suction pump, and then, may start the internal combustion engine. Thus, by opening the exhaust valve for the intake stroke cylinder, and sucking air from the exhaust passage using the suction pump, the airflow into the intake stroke cylinder is forcibly generated. Also, at the time of start of the internal combustion engine, the flow speed of the intake air in the intake port for the intake stroke cylinder is increased by the airflow generated by the suction pump, and air taken into the intake stroke cylinder by moving the piston downward. Therefore, the fuel is promptly introduced into the intake stroke cylinder,

[0012] In the above-described aspect, the start control apparatus for an internal combustion engine may further include an exhaust throttle valve provided in the exhaust passage at a position downstream of a connection position at which the suction pump is connected to the exhaust passage. A position of the exhaust throttle valve is switchable to a fully closing position in which the exhaust throttle valve fully closes the exhaust passage. When the predetermined start condition is fulfilled, the control means may switch the position of the exhaust throttle valve to the fully closing position, before operating the suction pump. Thus, by switching the position of the exhaust throttle valve to the fully closing position, an amount of air sucked from the intake stroke cylinder is increased. Therefore, the strength of the flow of the intake air into the intake stroke cylinder is further increased. Accordingly, the fuel is introduced into the intake stroke cylinder more promptly. [0013] A second aspect of the invention relates to a start control apparatus for an internal combustion engine that includes cylinders, and fuel injection valves provided in intake ports for the respective cylinders. When a predetermined stop condition is fulfilled, the start control apparatus stops the internal combustion engine, and then, when a predetermined start condition is fulfilled, the start control apparatus starts the internal

combustion engine. The start control apparatus includes cylinder identification means, position determination means, preliminary injection means, and start control means.

The cylinder identification means estimates a position at which a piston in each of the cylinders is to be stopped when the internal combustion engine is stopped, during a stop process period from when the predetermined stop condition is fulfilled until when the internal combustion engine is stopped, and identifies an intake stroke cylinder in which the piston is to be stopped in an intake stroke, based on the estimated position at which the piston in each of the cylinders is to be stopped. The position determination means determines whether the piston in the intake stroke cylinder identified by the cylinder identification means is to be stopped in a predetermined crank angle range set to correspond to a latter stage of the intake stroke. If the position determination means determines that the piston in the intake stroke cylinder is to be stopped in the predetermined crank angle range, the preliminary injection means causes the fuel injection valve for the intake stroke cylinder to inject fuel during the stop process period so that the fuel remains in the intake stroke cylinder when the internal combustion engine is stopped.. When the predetermined start condition is fulfiljed, and the preliminary injection means has caused the fuel injection valve for the intake stroke cylinder to inject the fuel during the stop process period, the start control means starts the internal combustion engine by combusting the fuel that remains in the intake stroke cylinder. [0014] According to the above-described aspect, when the internal combustion engine is to be stopped, the position, at which the piston in the intake stroke cylinder is to be stopped, is estimated. When it is determined that the piston is to be stopped in the predetermined crank angle range, the fuel is supplied to the intake stroke cylinder in advance before the internal combustion engine is stopped. Therefore, by combusting the fuel, the combustion in the intake stroke cylinder is improved at the time of start of the engine. Thus, the internal combustion engine is promptly started.

[0015] In the above-described aspect, when the preliminary injection means has caused the fuel injection valve for the intake stroke cylinder to inject the fuel during the stop process period, the start control means may prohibit the fuel injection valve for the

intake stroke cylinder from injecting the fuel at a time of start of the internal combustion engine.

[0016] In the above-described aspect, the predetermined crank angle range may be a range up to a crank angle at which the piston in the intake stroke cylinder reaches a bottom dead center of the intake stroke.

[0017] In the above-described aspect, the predetermined crank angle range may be a range up to a αank angle at which an intake valve is closed.

[0018] In the above-described aspect, ignition may be performed in the intake stroke cylinder first among all the cylinders at a time of start of the internal combustion engine.

[0019] A third aspect of the invention relates to a start control apparatus for an internal combustion engine that includes cylinders, and fuel injection valves provided in intake ports for the respective cylinders. The start control apparatus starts the internal combustion engine by supplying fuel to an intake stroke cylinder in which a piston is stopped in an intake stroke, using the fuel injection valve for the intake stroke cylinder, when a predetermined start condition is fulfilled. The start control apparatus includes a protruding portion provided in the intake port for each of the cylinders at a position upstream of the fuel injection valve to protrude into the intake port so that a flow passage sectional area of the intake port at the position at which the protruding portion is provided is smaller than a flow passage sectional area of the intake port at positions upstream and downstream of the protruding portion in a direction in which intake air flows.

[0020] According to the above-described aspect, the flow passage sectional area of the intake port is decreased at the position at which the protruding portion is provided. Therefore, the flow speed of the intake air is increased at this position. Therefore, the fuel is promptly supplied to the intake stroke cylinder together with the intake air. Also, the strength of the airflow formed in the intake stroke cylinder is increased by the intake air. Accordingly, an appropriate amount of the fuel is supplied to the intake stroke cylinder at the time of start of the internal combustion engine, and the combustion in the intake stroke cylinder is improved. Thus, the internal combustion engine is promptly

started.

[0021] As described above, the start control apparatus according to the invention supplies an appropriate amount of the fuel to the intake stroke cylinder, and improves the combustion in the intake stroke cylinder, even when the piston in the intake stroke cylinder is stopped at a position near the bottom dead center. Thus, the internal combustion engine is promptly started.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The foregoing and further objects, features and advantages of the invention will become apparent from the following description of embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:

FIG 1 is a diagram showing an example of an internal combustion engine provided with a start control apparatus according to a first embodiment of the invention; FIG 2 is a diagram schematically illustrating a method in which an ECU in FIG 1 restarts the engine;

FIG 3 is a diagram illustrating a predetermined crank angle range;

FIG 4 is a flowchart showing a restart control routine executed by the ECU in FIG i; FIG 5 is a diagram showing a start control apparatus according to a modified example of the first embodiment;

FIG 6 is a diagram showing an example of an internal combustion engine provided with a start control apparatus according to a second embodiment of the invention;

FIG 7 is a flowchart showing a restart control routine executed by an ECU in FIG 6; FIG 8 is a portion of a flowchart showing a restart control routine according to a modified example of the second embodiment;

FIG 9 is a portion of the flowchart following the portion of the flowchart in FIG 8;

FIG 10 is a diagram showing a start control apparatus according to a modified example of the second embodiment;

FIG U is a diagram showing an example of an internal combustion engine provided with a start control apparatus according to a third embodiment of the invention;

FIG 12 is a portion of a flowchart showing a restart control routine executed by an ECU in FIG 11; FIG 13 is a portion of the flowchart following the portion of the flowchart in FIG

12;

FIG 14 is a diagram showing an example of an internal combustion engine provided with a start control apparatus according to a fourth embodiment of the invention;

FIG 15 is a flowchart showing a preliminary injection control routine executed by an ECU in FIG 14; and

FIG 16 is a flowchart showing a restart control Toutine executed by the ECU in FIG 14.

DETAILED DESCRIPηQN OF EMBODIMENTS [0023] [First embodiment] FIG 1 is a diagram schematically showing an internal combustion engine provided with a start control apparatus according to a first embodiment of the invention. In FIG 1, an internal combustion engine (hereinafter, simply referred to as "engine") 1 is provided in a vehicle as a power source for driving the vehicle. The engine 1 includes four cylinders 2 (only one cylinder 1 is shown in FIG 1), and an intake passage 3 and an exhaust passage 4 that are connected to each cylinder 2.

[0024] A piston 5 is inserted in each cylinder 2 to reciprocate in the cylinder 2. In each cylinder 2, a combustion chamber 6 is formed by the piston 5 and a wall surface of the cylinder 2. Each piston 5 is connected to a crankshaft 9 by a connecting rod 7 and a crank arm 8. The phases of the pistons 5 in each pair of the cylinders 2 differ from each other by a crank angle of 180 degrees. An ignition plug 10, an intake valve 11, and an exhaust valve 12 arc provided for each cylinder 2. The ignition plug 10 is disposed on a substantially center line of the cylinder 2 in a manner such that an electrode portion protrudes into the cylinder 2. The intake valve 11 opens/closes an intake port 3a that

forms a part of the intake passage 3. The exhaust valve 12 opens/closes an exhaust port 4a that forms a part of the exhaust passage 4.

[0025] An injector 13, which may be regarded as a fuel injection valve, is provided in each intake port 3a. Thus, the engine 1 is configured as a port injection engine. In the intake passage 3, an air cleaner 14, a throttle valve 15, and a surge tank

16 are provided. The air cleaner 14 filters the intake air. The throttle valve 15 adjusts the intake air amount. The surge tank 16 suppresses pulsations of the intake air. As shown in FIG 1, the engine 1 is provided with a starter motor 17 that starts the engine 1 by rotating the crankshaft 9, The configuration of the engine 1 is the same as that of a known engine, and therefore, the detailed description thereof will be omitted.

[0026] A throttle valve 20 and an actuator 21 are provided for the intake port 3a for each cylinder 2. The throttle valve 20 may be regarded as the valve means. The position of the throttle valve 20 is switchable between a closing position Pl and an opening position P2. When the throttle valve 20 is in the closing position Pl, the throttle valve 20 protrudes into the intake port 3a, thereby decreasing a flow passage sectional area of the intake port 3a. When the throttle valve 20 is in the opening position P2, the throttle valve 20 fully opens the intake port 3a. The actuator 21 drives the throttle valve 20 between the closing position Pl and the opening position P2. As

$hown in FIG 1, the throttle valve 20 is disposed in the intake port 3a at a position upstream of the injector 13.

[0027] The operation of the actuator 21 is controlled by an engine control unit (ECU) 30. The ECU 30 is configured as a computer that includes a microprocessor, and peripheral devices required for the operation of the microprocessor, such as a RAM and a ROM. The ECU 30 executes processes required for controlling the operating state of the engine 1 according to programs stored in the ROM. For example, the ECU 30 detects a rotational speed and an intake air amount of the engine 1 based on signals output from predetermined sensors, and controls an amount of fuel injected from the injector 13 so that an actual air-fuel ratio becomes equal to a predetermined air-fuel ratio. When the ECU 30 executes the control, the ECU 30 refers to the signals output from the

sensors provided in the engine 1. For example, the ECU 30 refers to the signals output from a crank angle sensor 31 and an airflow meter 32. The crank angle sensor 31 outputs a signal corresponding to the phase (crank angle) of the crankshaft 9, and the airflow meter 32 outputs a signal corresponding to the intake air amount. Although not shown in the figures, other sensors, are connected to the ECU 30.

[0028] When a predetermined stop condition is fulfilled, the ECU 30 stops fuel injection to the engine 1 to stop the operation of the engine 1. When a predetermined restart condition is fulfilled, the ECU 30 restarts the engine 1. That is, the ECU 30 executes a so-called idling stop control for the engine 1. The predetermined stop condition is fulfilled, for example, when a brake pedal continues to be operated, and the vehicle speed continues to be 0 for a predetermined period.' If the vehicle includes an automatic transmission, the restart condition is fulfilled, for example, when the brake pedal is released. If the vehicle includes a manual transmission, the restart condition is fulfilled, for example, when a shift lever is moved from a neutral position to a first gear position, and a clutch pedal is depressed. The stop condition and the restart condition may be set in the same manner as in known technologies relating to idling stop control.

[0029] An outline of a method in which the ECU 30 restarts the engine 1 will be described with reference to FIG 2. When the restart condition is fulfilled at time TO, the ECU 30 causes the starter motor 17 to rotate the crankshaft 9, that is, to perform so-called cranking.

[0030] Next, at time Tl, the ECU 30 operates the injector 13, which is provided in the intake port 3a for the cylinder (intake stroke cylinder) 2 in which the piston 5 is stopped in an intake stroke when the engine 1 is stopped, to inject fuel. The piston 5 in the intake stroke cylinder moves to a top dead center of a compression stroke second among the pistons 5 in all the cylinders 2, when the engine 1 is restarted. Therefore, hereinafter, the intake stroke cylinder will be referred to as "second TDC cylinder". In the second TDC cylinder, the piston 5 may be stopped at a position near a bottom dead center (BDC) at the time of start of the engine 1. In this case, an intake air amount taken into the second TDC cylinder at the time of start of the engine 1 may be decreased,

as described later. Also, the cylinder, in which the piston 5 moves to the top dead center of the compression stroke first among the pistons 5 in all the cylinders, will be referred to as "first TDC cylinder". The cylinder, in which the piston 5 moves to the top dead center of the compression stroke third among the pistons 5 in all the cylinders, will be referred to as "third TDC cylinder".

[0031] Then, the ECU 30 operates the ignition plug 10 for the second TDC cylinder so that the fuel is combusted, at time T2 at which the piston 5 in the second TDC cylinder reaches the top dead center of the compression stroke. That is, in the second TDC cylinder, ignition is performed first, when the engine 1 is restarted. Then, the ECU 30 executes a known control that operates the injector 13 and the ignition plug 10 for each cylinder 2 so that combustion is performed in each cylinder 2. By executing this control, the engine 1 is restarted.

[0032] As shown in FlG 3, if the piston 5 in the second TDC cylinder is stopped in a predetermined crank angle range θ set to correspond to the latter stage of the intake stroke, that is, the predetermined crank angle range θ set to be near the bottom dead center (BDC) when the engine 1 is restarted, the piston 5 in the second TDC cylinder is hardly moved during the intake stroke when the engine 1 is restarted. Therefore, the amount of intake air taken into the second TDC cylinder is decreased. Also, as shown in FIG 3, a valve open period (intake period), in which the intake valve 11 is open, is decreased. Therefore, fuel injected from the injector 13 is less likely to enter the second

TDC cylinder. In the embodiment, the intake stroke cylinder is identified, and the predetermined crank angle range is set to a predetermined range from the bottom dead center. However, the predetermined orank angle range may be set to a predetermined range from the timing at which the intake valve is closed. [0033] In this case, the ECU 30 switches the position of the throttle valve 20 to the closing position Pl when the engine 1 is restarted. As a result, a flow speed of the intake air in the intake port 3a is increased, and fuel is supplied to the cylinder 2 using the intake air. Therefore, even when the piston 5 in the second TDC cylinder is stopped in the predetermined crank angle range θ, the intake air and fuel are appropriately supplied

to the second TDC cylinder when the engine 1 is restarted. Thus, the throttle valve 20, which inσeases the flow speed of the intake air in the intake port 3a, may be regarded as the flow speed changing means according to the invention.

[0034] FIG 4 shows a restart control routine. The ECU 30 repeatedly executes the restart control routine at predetermined time intervals, to restart the engine 1 in the above-described manner when the engine 1 is stopped by the idling stop control. The

ECU 30, which executes the control routine, may be regarded as the control means according to the invention. In the control routine in FIG 4, first, in step SIl, the ECU

30 determines whether the above-described predetermined restart condition is fulfilled. When the ECU 30 determines that the restart condition is not fulfilled (NO in step SIl), the ECU 30 ends the current control routine.

[0035] When the ECU 30 determines that the restart condition is fulfilled (YES in step SIl), the routine proceeds to step S12. In step S12, the ECU 30 determines a position at which the piston 5 in each cylinder 2 is stopped, by referring to the signal output from the crank angle sensor 31. The ECU 30 identifies the second TDC cylinder (intake stroke cylinder) based on the determined position at which the piston 5 in each cylinder 2 is stopped. As is generally known, the crank angle is determined using a reference crank angle when the pistons 5 in the four cylinders 2 are in predetermined positions (for example, when the piston 5 in one of the cylinders 2 is at a top dead center of the intake stroke). Therefore, it is possible to determine the position at which the piston 5 in each cylinder 2 is stopped, based on the crank angle when the engine 1 is stopped.

[0036] Then, the ECU 30 identifies the second TDC cylinder based on the determined position at which the piston 5 in each cylinder 2 is stopped. Subsequently, in step S13, the ECU 30 determines whether the piston in the second TDC cylinder is stopped in the predetermined crank angle range θ shown in FlG 3. When the ECU 30 executes this process, the ECU 30 may be regarded as the position determination means. When the ECU 30 determines that the piston 5 in the second TDC cylinder is stopped outside the predetermined crank angle range θ (NO in step S13), the routine skips step

S14, and proceeds to step S 15. When the ECU 30 determines that the piston 5 in the second TDC cylinder is stopped in the predetermined crank angle range θ (YES in step S13), the routine proceeds to step S14. In step S14, the ECU 30 operates the actuator 21 to switch the position of the throttle valve 20 to the closing position Pl. [0037] Subsequently, in step S15, the ECU 30 operates the starter motor 17 to start cranking. If the starter motor 17 is being operated, the ECU 30 maintains the starter motor 17 in the operated state.

[0038] Next, in step S16, the ECU 30 determines whether the injector 13 for the second TDC cylinder needs to inject fuel. The fuel injection riming is set according to a known setting method so that fuel is appropriately supplied to the cylinder. When the

ECU 30 determines that the injector 13 for the second TDC cylinder does not need to inject fuel (NO in step S16), the routine skips step S17, and proceeds to step S18. When the ECU 30 determines that the injector 13 for the second TDC cylinder needs to inject fuel (YES in step S16), the routine proceeds to step S17. In step S17, the ECU 30 causes the injector 13 for the second TDC cylinder to inject fuel.

[0039J Subsequently, in step S18, the ECU 30 determines whether the ignition plug 10 for the second TDC cylinder needs to be operated to ignite an air-fuel mixture in the second TDC cylinder. When the ECU 30 determines that the ignition plug 10 for the second TDC cylinder does not need to be operated for ignition (NO in step S 18), the routine skips step S 19, and proceeds to step S20. When the ECU 30 determines that the ignition plug 10 for the second TDC cylinder needs to be operated for ignition (YES in step S18), the routine proceeds to step S19. In step S19, the ECU 30 operates the ignition plug 10 for the second TDC cylinder so that the ignition plug 10 ignites the air-fuel mixture in the second TDC cylinder. [0040] Next, in step S20, the ECU 30 determines whether a process of starting the engine 1 is completed. The ECU 30 determines whether the process of starting the engine 1 is completed, for example, based on the rotational speed of the engine 1. In this case, when the rotational speed of the engine 1 is higher than the rotational speed at which the self-sustaining operation of the engine 1 is started, the ECU 30 determines that

the process of starting the engine 1 is completed. When the ECU 30 determines that the process of starting the engine 1 is incomplete*! (NO in step S20), the ECU 30 ends the current control routine. When the ECU 30 determines that the process of starting the engine 1 is completed (YES in step S20), the routine proceeds to step S21. In step S21, the ECU 30 stops the starter motor 17.

[0041] Subsequently, in step S22, the ECU 30 operates the actuator 21 to switch the position of the throttle valve 20 to the opening position P2. Then, the ECU 30 ends the current control routine.

{0042] By executing the control routine in FIG 4, the ECU 30 switches the position of the throttle valve 20 to the closing position Pl when the piston S in the second

TDC cylinder is stopped in the predetermined crank angel range θ set to be near the bottom dead center (BDC). Thus, the start control apparatus increases the flow speed of the intake air in the intake port 3a, and promptly delivers fuel into the second TDC cylinder by increasing the flow speed. Also, by increasing the flow speed of the intake air in the intake port 3a, the start control apparatus increases the strength of an airflow formed in the second TDC cylinder, such as a swirl flow or a tumble flow. This improves the combustion in the second TDC cyb'nder at the time of start of the engine 1.

Because the start control apparatus suppresses a misfire in the second TDC cylinder at the time of start of the engine 1, the engine 1 is promptly started. [0043] [Modified example of the first embodiment] FIG 5 shows a start control apparatus in a modified example of the first embodiment. The modified example in FIG

5 is the same as the first embodiment in FIG 1, except that a protruding portion 40 is provided in the intake port 3a for each cylinder at a position upstream of the injector 13 to protrude into the intake port 3a, instead of providing the throttle valve 20. Therefore, in FIG 5, the same and corresponding portions as those in FIG 1 are denoted by the same reference numerals, and the description thereof will be omitted. The protruding portion

40 is provided to protrude into the intake port 3a. Thus, the flow passage sectional area of the intake port 3a at the position at which the protruding portion 40 is provided is smaller than the flow passage sectional area of the intake port 3a at positions upstream

and downstream of the protruding portion 40 in a direction in which the intake air flows. That is, the protruding portion 40 may be regarded as being substantially the same as the throttle valve 20 fixed in the closed position Pl shown in FIG 1.

[0044] In the modified example shown in FIG 5 as well, the start control apparatus increases the flow speed of the intake air in the intake port 3a using the protruding portion 40. Therefore, it is possible to promptly deliver fuel into the second

TDC cylinder using the intake air. Also, the start control apparatus increases the strength of the airflow formed in the second TDC cylinder, such as a swirl flow or a tumble flow. Thus, the start control apparatus improves the combustion in the second TDC cylinder at the time of start of the engine 1, and promptly starts the engine 1.

[0045] [Second embodiment] FIG 6 is a diagram showing an example of an internal combustion engine provided with a start control apparatus according to a second embodiment of the invention. In FlG 6, the same and corresponding portions as those in FIG 1 are denoted by the same reference numerals, and the description thereof will be omitted. As shown in FIG 6, in the start control apparatus according to the second embodiment, an air pump 50 and an air introduction passage 51 are provided. The air pump 50 may be regarded as the pump according to the invention. The air introduction passage 51 introduces air discharged from the air pump 50 into a portion of the intake port 3a for each cylinder 2, which is upstream of the injector 13. In the air introduction passage 51, an opening/closing valve 52, which opens/closes the air introduction passage

51, is provided. Also, a variable valve operating mechanism 60 is provided. The variable valve operating mechanism 60 opens/closes at least the exhaust valve 12 regardless of a rotational speed of the crankshaft 9, A known variable valve operating mechanism is used as the variable valve operating mechanism 60. For example, an electromagnetic operating mechanism that opens/closes the exhaust valves 12 using an electromagnetic coil, or a valve operating mechanism that operates a cam for opening/closing the exhaust valves 12 using an electric motor may be used as the variable valve operating mechanism 60.

[00461 The ECU 30 in the second embodiment also executes the idling stop

control for the engine 1. The ECU 30 uses the air pump SO to supply air to the second TDC cylinder, thereby improving the combustion at the time of restart of the engine 1. Thus, the engine is promptly restarted. FIG 7 shows a restart control routine. The ECU 30 in FIG 6 repeatedly executes the restart control routine at predetermined time intervals to restart the engine 1 when the engine 1 is stopped by the idling stop control. The control routine in FIG 7 is the same as the control routine in FIG 4, except that step S31 is provided instead of step S14, and step S32 is provided instead of step S22. Therefore, in FIG 7, the same processes as those in FIG 4 are denoted by the same reference numerals, and the description thereof will be omitted. [0047] In the control routine in FTG 7, in steps SIl to S13, the ECU 30 executes the same processes as those in steps SIl to S13 in FIG 4. When the ECU 30 determines that the piston 5 in the second TDC cylinder is stopped outside the predetermined crank angle range θ in step S13 (NO in step S13), the routine skips step S31, and proceeds to step S15. When the ECU 30 determines that the piston S in the second TDC cylinder is stopped in the predetermined crank angle range θ (YES in step S 13), the routine proceeds to step S31. In step S31, the ECU 30 starts the air pump 50, and opens the opening/closing valve 52. If the air pump 50 is being operated, and the opening/closing valve 52 is in the open state, the ECU 30 maintains the air pump 50 in the operated state, and maintains the opening/closing valve 52 in the open state. [0048] Then, the routine proceeds to step S15. In steps S15 to S21, the ECU 30 executes the same processes as those in steps S 15 to S21 in FIG 4. After the ECU 30 stops the starter motor 17 in step S21, the routine proceeds to step S32. In step S32, the ECU 30 stops the air pump 50, and closes the opening/closing valve 52. Then, the ECU 30 ends the current control routine. [0049J When the piston 5 in the second TDC cylinder is stopped in the predetermined crank angle range θ, the start control apparatus according to the second embodiment introduces air into the intake port 3a for the second TDC cylinder by operating the air pump 50. Therefore, appropriate amount of air required to combust fuel is suppb ^' ed to the second TDC cylinder. Also, the start control apparatus forcibly

generates (he airflow in the intake port 3a. Therefore, it is possible to introduce fuel into the second TDC cylinder using the airflow. Further, the start control apparatus supplies air to the second TDC cylinder using the air pump SO, in addition to the air taken into the second TDC cylinder by moving the piston 5 downward. Therefore, the flow speed of the intake air in the intake port 3a is increased. Thus, the start control apparatus delivers fuel into the second TDC cylinder, and increases the strength of the airflow formed in the second TDC cylinder, thereby improving the combustion in the second TDC cylinder at the time of restart of the engine 1. Accordingly, the start control apparatus promptly restarts the engine 1. The air pump SO, which supplies air into the intake port 3a for the second TDC cylinder, may be regarded as the air supply means and the intake flow speed changing means according to the invention.

[0050] [Modified example 1 of the second embodiment] FIQ 8 and FIG 9 show a modified example of the restart control routine executed by the ECU 30 in FIG 6. FIG 9 shows a portion of a flowchart following a portion of the flowchart shown in FIG 8. The modified example of the routine in FIG 8 and FIG 9 is the same as the routine in FIG 7, except that step S41 is provided between step S 13 and step S31, and steps S42 and S43 are provided between step S17 and step S18. Therefore, in FIG 8 and FIG 9, the same processes as those in FIG 7 are denoted by the same reference numerals, and the description thereof will be omitted. [0051] In the control routine in FIG 8, in steps SIl to S13, the ECU 30 executes the same processes as those in steps SIl to S 13 in FIG 7. When the ECU 30 determines that the piston S in the second TDC cylinder is stopped outside the predetermined crank angle range θ in step S13 (NO in step S13), the routine skips steps S41 and S31, and proceeds to step SlS. When the ECU 30 determines that the piston S in the second TDC cylinder is stopped in the predetermined crank angle range θ (YES in step S13), the routine proceeds to step S41. In step S41, the ECU 30 executes a forcible valve opening control that forcibly opens the exhaust valve 12 for the second TDC cylinder, by controlling the variable valve operating mechanism 60. Subsequently, in step S31, the

ECU 30 starts the air pump SO, and opens the opening/closing valve 52. Then, the

routine proceeds to step S15. In steps S15 to S17, the ECU 30 executes the same processes as those in steps S 15 to S17 in FIG 7.

[0052] When the ECU 30 determines that the injector 13 for the second TDC cylinder does not need to inject fuel in step S 16, or when the ECU 30 causes the injector 13 for the second TDC cylinder to inject fuel in step S17, the routine proceeds to step S42.

In step S42, the ECU 30 determines whether the exhaust valve 12 for the second TDC cylinder needs to be closed. If the exhaust valve 12 for the second TDC cylinder is not closed during the compression stroke, the air-fuel mixture in the second TDC cylinder is not compressed during the compression stroke. Therefore, for example, the timing at which the exhaust valve 12 for the second TDC cylinder is closed is set to a timing at which the compression stroke of the second TDC cylinder is started.

[0053] When the ECU 30 determines that the exhaust valve 12 for the second

TDC cylinder does not need to be closed in step S42 (NO in step S42), the routine skips step S43, and proceeds to step S18. When the ECU 30 determines that the exhaust valve 12 for the second TDC cylinder needs to be closed (YES in step S42), the routine proceeds to step S43. In step S43, the ECU 30 executes a valve closing control that closes the exhaust valve 12 for the second TDC cylinder, by controlling the variable valve operating mechanism 60. Then, the routine proceeds to step S18 in FIG 9. In subsequent steps, the ECU 30 executes the same processes as those in FIG 7. [0054] When ah" is introduced into the second TDC cylinder using the air pump

50, the start control apparatus in the modified example opens the exhaust valve 12 for the second TDC cylinder. Therefore, air flowing from an intake side to an exhaust side is formed in the second TDC cylinder. Thus, the start control apparatus increases the strength of the flow of the intake air into the second TDC cylinder, as compared to when the exhaust valve 12 is maintained in a closed state. Thus, the start control apparatus introduces fuel into the second TDC cylinder more promptly. Accordingly, the start control apparatus delivers fuel into the second TDC cylinder, and increases the airflow formed in the second TDC cylinder, thereby improving the combustion in the second

TDC cylinder at the time of restart of the engine 1.

[00551 [Modified example 2 of the second embodiment] FIG 10 shows a start control apparatus in a modified example 2 of the second embodiment. In this modified example, the engine 1 includes a supercharger 70 that is driven by an electric motor 71. When the piston 5 in the second TDC cylinder is stopped in the predetermined crank angle range θ at the time of restart of the engine 1, a turbine 70a of the supercharger 70 is driven by the electric motor 71 to introduce air into the second TDC cylinder.

[0056] By introducing air into the second TDC cylinder using the supercharger 70, the start control apparatus in the modified example 2 of the second embodiment increases the flow speed of the intake air in the intake port 3a for the second TDC cylinder, as well as the start control apparatus shown Ln FIG 6. Thus, the start control apparatus in the modified example 2 of the second embodiment improves the combustion in the second

TDC cylinder at the time of restart of the engine 1, and to promptly start the engine 1.

Also, the start control apparatus in the modified example 2 shown in FIG 10 increases the flow of the intake air flowing into the second TDC cylinder, by maintaining the exhaust valve 12 for the second TDC cylinder in the open state when the supercharger 70 is operated at the time of restart of the engine 1. Therefore, the start control apparatus further improves the combustion in the second TDC cylinder. In this case, the supercharger 70 may be regarded as the air supply means and the intake flow speed changing means according to the invention. [0057] [Third embodiment] FIG 11 shows an example of an internal combustion engine provided with a start control apparatus according to a third embodiment of the invention. In FIG 11, the same and corresponding portions as those in FIG 1 and FIG 6 are denoted by the same reference numerals, and the description thereof will be omitted. As shown in FIG 11, in the start control apparatus according to the third embodiment, a vacuum pump 80 and an air discharge passage 81 are provided. The vacuum pump 80 may be regarded as a suction pump. The air discharge passage 81 connects the exhaust port 4a for each cylinder 2 to the vacuum pump 80. In the exhaust passage 4, an exhaust gas purification catalyst 82 and an exhaust throttle valve 83 are provided. The position of the exhaust throttle valve 83 is switchable to. a fully closing

position in which the exhaust throttle valve 83 fully closes the exhaust passage 4. The exhaust throttle valve 83 may be regarded as the exhaust throttle valve means. Further, the engine 1 is provided with the variable valve operating mechanism 60 that opens/closes at least the exhaust valves 12, regardless of the rotational speed of the crankshaft 9.

[0058] The ECU 30 in the third embodiment also executes the idling stop control for the engine 1. The ECU 30 uses the vacuum pump 80 to supply air into the second

TDC cylinder at the time of restart of the engine 1, thereby improving the combustion, and promptly restarting the engine 1. FIG 12 and FIG 13 show a restart control routine. The ECU 30 in FIG 11 repeatedly executes the restart control routine at predetermined time intervals to restart the engine 1 when the engine 1 is stopped by the idling stop control. FIG 13 shows a portion of a flowchart following a portion of the flowchart shown in FIG 12. The control routine in FIG 12 and FIG 13 is the same as the control routine in FIG 4, except that steps S51 and S41 are provided between step S13 and step S15, and steps S42, S43, and S52 are provided between step 17 and step 18. Therefore, in FIG 12 and FIG 13, the same processes as those in FIG 4 and FIG 7 to FIG 9 are denoted by the same reference numerals, and the description thereof will be omitted.

[0059] In the control routine in FIG 12, in step SIl to step S13, the ECU 30 executes the same processes as those in step SIl to step 13 in FIG 4. In step S13, when the ECU 30 determines that the piston 5 for the second TDC cylinder is stopped outside the predetermined αank angle range θ (NO in step S13), the routine skips steps S51 and

S41, and proceeds to step S15. When the ECU 30 determines that the piston 5 for the second TDC cylinder is stopped in the predetermined crank angle range θ (YES in step

S13), the routine proceeds to step S51. In step S51, the ECU 30 starts the vacuum pump 80. If the vacuum pump 80 is being operated, the ECU 30 maintains the vacuum pump

80 in the operated state.

[0060] Subsequently, in step S41, the ECU 30 executes the forcible valve opening control that forcibly opens the exhaust valve 12 for the second TDC cylinder, by controlling the variable valve operating mechanism 60. Then, the routine proceeds to

step S15. In steps S15 to S 17, the ECU 30 executes the same processes as those in steps S15 to S17 in FIG 7.

[0061] When the ECU 30 determines that the injector 13 for the second TDC cylinder does not need to inject fuel in step Sl 6 (NO in step S 16), or when the ECU 30 causes the injector 13 for the second TDC cylinder to inject fuel in step S17, the routine proceeds to step S42. In step S42, the ECU 30 determines whether the exhaust valve 12 for the second TDC cylinder needs to be closed When the ECU 30 determines that the exhaust valve 12 for the second TDC cylinder does not need to be closed (NO in step S42), the routine skips steps S43 and SS2, and proceeds to step S 18. When the ECU 30 determines that the exhaust valve 12 for the second TDC cylinder needs to be closed (YES in step S42), the routine proceeds to step S43. In step S43, the ECU 30 executes the valve closing control that closes the exhaust valve 12 for the second TDC cylinder, by controlling the variable valve operating mechanism 60.

[0062] Subsequently, in step S52, the ECU 30 stops the vacuum pump 80. Then, the routine proceeds to step S18 in FIG 13. In steps S18 to S21, the ECU 30 executes the same processes as those in steps S18 to S21 in FIG 4. Then, after the ECU 30 stops the starter motor 17 in step S21, the ECU 30 ends the current control routine.

[0063] When the piston 5 for the second TDC cylinder is stopped in the predetermined crank angle range θ, the start control apparatus according to the third embodiment opens the exhaust valve 12 for the second TDC cylinder, and sucks air from the exhaust port 4a using the vacuum pump 80. Thus, air is discharged from the second

TDC cylinder, and thus, the airflow from the intake passage 3 to the second TDC cylinder is formed. Also, the start control apparatus increases the flow speed of the intake air in the intake port 3a. Thus, the start control apparatus forcibly generates the airflow in the second port 3a for the second TDC cylinder, thereby introducing the fuel into the second

TDC cylinder using the airflow. Therefore, the start control apparatus delivers fuel into the second TDC cylinder, thereby improving the combustion in the second TDC cylinder at the time of restart of the engine 1. Accordingly, the start control apparatus promptly restarts the engine 1. Thus, the vacuum pump 80, which sucks air from the second TDC

cylinder, thereby increasing the flow speed of the intake air in the intake port 3a for the second TDC cylinder, may be regarded as the flow speed changing means according to the invention.

[0064] In the start control apparatus according to the third embodiment, the exhaust throttle valve 83 may be placed in a fully closing position during a period in which the vacuum pump 80 is operated to suck air from the exhaust port 4a. By placing the exhaust throttle valve 83 in the fully closing position in the above-described manner, it is possible to prevent a reverse airflow in the exhaust passage 4. This increases the amount of air sucked from the second TDC cylinder. Thus, the start control apparatus further increases the strength of the flow of the intake air into the second TDC cylinder.

Accordingly, the start control apparatus introduces the fuel into the second TDC cylinder more promptly.

[0O65J [Fourth embodiment] FIG 14 shows an example of an internal combustion engine provided with a start control apparatus according to a fourth embodiment of the invention. In FIG 14, the same and corresponding portions as those in FIG 1 are denoted by the same reference numerals, and the description thereof will be omitted. The ECU 30 in the fourth embodiment also executes the idling stop control for the engine 1. As well as the ECU 30 in the other embodiments, the ECU 30 in the fourth embodiment restarts the engine 1 by executing the control so that the combustion is performed in the second TDC cylinder first among all the cylinders at the time of restart of the engine 1. The fourth embodiment differs from the other embodiments as follows. In the fourth embodiment, the position at which the piston 5 in each cylinder 2 is to be stopped when the engine 1 is stopped is estimated during a period from when the predetermined stop condition is fulfilled until when the engine 1 is stopped. Based on the estimated position at which the piston 5 in each cylinder 2 is to be stopped, it is determined whether the piston 5 in the second TDC cylinder is to be stopped in the predetermined crank angel range θ. When it is determined that the piston 5 in the second TDC cylinder is to be stopped in the predetermined crank angel range θ, a preliminary injection control is executed to supply fuel into the second TDC cylinder

before the engine 1 is stopped, so that the fuel remains in the second TDC cylinder when the engine 1 is stopped.

[0066] FIG 15 shows a preliminary injection control routine. The ECU 30 repeatedly executes the preliminary injection control routine at predetermined time intervals during the operation of the engine 1 to execute the preliminary injection control when the engine 1 is to be stopped. FlG 16 shows a restart control routine. The ECU 30 repeatedly executes the restart control routine at predetermined time intervals to restart the engine 1 when the engine 1 is stopped by the idling stop control. When the ECU 30 executes the preliminary injection control routine, the ECU 30 may be regarded as the preliminary injection means according to the invention. When the ECU 30 executes the restart control routine in FIG 16, the ECU 30 may be regarded as the start control means. [0067] First; the preliminary injection control routine in FIG 15 will be described. In the control routine in FIG 15, first, in step S61, the ECU 30 determines whether the predetermined stop condition is fulfilled. When the ECU 30 determines that the predetermined stop condition is not fulfilled (NO in step S61), the ECU 30 ends the current control routine. When the ECU 30 determines that the predetermined stop condition is fulfilled (YES in step S61), the routine proceeds to step S62. In step S62, the ECU 30 performs fuel restriction to stop fuel supply to each cylinder 2 by stopping the injector 13 for each cylinder in a closed state. Subsequently, in step S63, the ECU 30 estimates the position at which the piston 5 in each cylinder 2 is to be stopped when the engine 1 is stopped. Based on the estimated position at which the piston 5 in each cylinder 2 is to be stopped, the ECU 30 identifies the second TDC cylinder. For example, a relation between the rotational speed of the crankshaft 9 after the fuel restriction is performed and a crank angle at which the crankshaft 9 is to be stopped when the engine 1 is stopped (hereinafter, this crank angle will be referred to as "estimated stop angle") is obtained in advance through experiment or the like, and a map indicating the relation is stored in the ROM of the ECU 30. The position, at which the piston 5 in each cylinder 2 is to be stopped when the engine 1 is stopped, is estimated by referring to the map. By determining the estimated stop angle, the ECU 30 estimates the position at

which the piston S in each cylinder 2 is to be stopped, based on the estimated stop angle. Then, based on the estimated position at which the piston 5 in each cylinder 2 is to be stopped, the ECU 30 identifies the second TDC cylinder (intake stroke cylinder). When the ECU 30 executes the process, the ECU 30 may be regarded as the cylinder identification means according to the invention.

[0068] Next, in step S64, the ECU 30 determines whether the estimated position, at which the piston 5 in the second TDC cylinder is to be stopped, is in the predetermined crank angle range θ. When the ECU 30 determines that the estimated position, at which the piston 5 is to be stopped, is outside the predetermined crank angle range θ (NO in step S64), the ECU 30 ends the current control routine. When the ECU 30 determines that the estimated position, at which the piston 5 is to be stopped, is in the predetermined crank angle range θ (YES in step S64), the routine proceeds to step S65. In step S65, the ECU 30 determines whether the injector 13 for the second TDC cylinder needs to inject fuel. In this embodiment, when it is determined that the piston 5 in the second TDC cylinder is to be stopped in the predetermined crank angle range θ (YES in step

S64), it is necessary to make the fuel remain in the second TDC cylinder when the engine

1 is stopped. Therefore, the timing at which the injector 13 for the second TDC cylinder injects fuel is set to, for example, a last opening timing of the intake valve 11 for the second TDC cylinder during a period from when the predetermined stop condition is fulfilled until when the engine 1 is stopped. When the ECU 30 determines that the injector 13 for the second TDC cylinder does not need to inject fuel, the ECU 30 ends the current control routine.

[0069] When the ECU 30 determines that the injector 13 for the second TDC cylinder needs to inject the fuel, the routine proceeds to step S66. In step S66, the ECU 30 executes the preliminary injection control so that the injector 13 for the second TDC cylinder injects fuel. Subsequently, in step S67, the ECU 30 turns on a preliminary injection flag indicating that the preliminary injection control has been executed. Then, the ECU 30 ends the current control routine.

10070] Next, the restart control routine in FIG 16 will be described. In FIG 16,

the same processes as those in FIG 4 are denoted by the same reference numerals, and the description thereof will be omitted. In the control routine in FIG 16, first, in step

SIl, the ECU 30 determines whether the restart condition is fulfilled. When the ECU

30 determines that the predetermined restart condition is not fulfilled (NO in step SIl), the ECU 30 ends the current control routine. When the ECU 30 determines that the restart condition is fulfilled (YES in step SIl), the routine proceeds to step S71. In step

S71,- the ECU 30 determines whether the preliminary injection flag is on. When the

ECU 30 determines that the preliminary injection flag is off (NO in step S71), the routine skips step S72, and proceeds to step S73. When the ECU 30 determines that the preliminary injection flag is on (YES in step S71), the routine proceeds to step S72. In step S72, the ECU 30 prohibits the injector 13 for the second TDC cylinder from injecting fuel first among the injectors 13 for all the cylinders at the time of restart of the engine 1. That is, in this case, the injector 13 for the third TDC cylinder injects fuel first among the injectors 13 for all the cylinders. Next, in step S73, the ECU 30 executes a start control that starts the engine 1. In the start control, for example, the ECU 30 executes a cranking control using the starter motor 17, a control of fuel injection from each injector 13, and a control of ignition of the air- fuel mixture in each cylinder using each ignition plug 10 at known appropriate timings.

[0071] Next, in step S20, the ECU 30 determines whether a process of starting the engine 1 has been completed. When the ECU 30 determines that the process of starting the engine 1 has not been completed (NO in step S20), the ECU 30 ends the current control routine. When the ECU 30 determines that the process of starting the engine 1 has been completed (YES in step S20), the routine proceeds to step S21. In step S21, the ECU 30 stops the starter motor 17. Subsequently, in step S74, the ECU 30 turns the preliminary injection flag off. Then, the ECU 30 ends the current control routine.

[0072] The start control apparatus according to the fourth embodiment determines the estimated position at which the piston 5 in the second TDC cylinder is to be stopped when the engine 1 is stopped. When the start control apparatus determines that the piston 5 is to be stopped in the predetermined crank angle range θ, fuel is supplied to the

second TDC cylinder before the engine 1 is stopped Therefore, fuel is combusted at the time of restart of the engine. Thus, the start control apparatus improves the combustion in the second TDC cylinder at the time of restart of the engine 1. Accordingly, the start control apparatus promptly restarts the engine 1. [0073] Further, the start control apparatus according to the fourth embodiment may execute at least one of the controls relating to the intake air in the first to third embodiments, thereby further improving the combustion, and promptly restarting the engine 1.

[0074] The invention is not limited to the above-described embodiments, and the invention may be realized in various embodiments. For example, the engine to which the invention is applied is not limited to the four-cylinder engine. For example, the invention may be applied to engines with three, six, eight, ten, and twelve cylinders.

The arrangement of the cylinders is not limited to a specific arrangement. For example, the invention may be applied to an in-line internal combustion engine, or a V-engine. The invention need not necessarily be applied to the case where the engine is stopped and started by the idling stop control. The invention may be applied to .the case where the engine is stopped by turning an ignition switch off. Accordingly, the invention need not necessarily be applied to the engine for which the idling stop control is executed. The invention may be applied to the case where an engine, for which the idling stop control is not executed, is started.

[0075] The invention need not necessarily be applied to the engine in which the combustion is performed in the second TDC cylinder first among all the cylinders at the time of start of the engine. The invention may be applied to an engine in which the combustion is performed in the first TDC cylinder first among ail the cylinders at the time of start of the engine.

[0076] While the invention has been described with reference to example embodiments thereof, it is to be understood that the invention is not limited to the described embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various

elements of the disclosed invention are shown in various example combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the scope of the appended claims.