JP2008180093A - Engine starting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine starting device capable of surely keeping stopping position of the piston of a start starting cylinder within a range in which an engine can be started by itself without requiring an additional mechanism and an additional sensing system. <P>SOLUTION: In this engine starting device which is equipped with fuel supply means 7A, 7B to directly inject and supply fuel to the inside of a combustion chamber, and spark ignition performing means 8A, 8B to perform spark ignition of mixed air in the combustion chamber, and which restarts the engine without assistance of a starter motor by injecting and supplying fuel to the cylinder in an expansion stroke after the engine stops and performing spark ignition by using these means, a combustion chamber pressure adjusting means 2 to adjust a fuel combustion chamber pressure when the engine stops so that the engine restricts the stopping position of a crank shaft within the range in which the engine can start by itself is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine (internal combustion engine) starter, and more particularly to an improvement in start-up technology for a direct injection gasoline engine.

A fuel injection valve that directly injects fuel into the combustion chamber and an ignition plug that performs spark ignition on the air-fuel mixture in the combustion chamber. These fuel injection valves and the ignition plug are used for the expansion stroke after the engine is stopped. A so-called ignition start engine has been proposed in which fuel is injected into a cylinder and spark ignition is performed to restart the engine without the help of a starter motor (see Patent Document 1).
JP 2002-39038 A

  By the way, in an ignition start engine, when the engine is stopped, it is essential to stop the piston position of the start cylinder within a range from 5 ° after top dead center to 110 ° after top dead center, that is, within a range where self-start is possible. It becomes the condition of.

  However, since the piston stop position of the start start cylinder generally varies widely, the technique of Patent Document 1 cannot always stop the piston stop position of the start start cylinder within a self-startable range. I have a lot of ingenuity.

  (1) A mechanical brake mechanism is provided to stop the crankshaft 12 at a position where the self-start can be performed when the engine is stopped, and the piston stop position of the start-start cylinder can be self-started mechanically by this brake mechanism. Within a range (10 ° after top dead center to 140 ° after top dead center).

  (2) A starter motor is provided in the same manner as in the conventional engine, and when the piston stop position of the start start cylinder is not within the self-startable range, the starter motor can be driven to self-start the piston stop position of the start start cylinder. Move into the correct range.

  (3) Since it is necessary to calculate the fuel injection amount according to the amount of intake air in the combustion chamber of the start cylinder at the time of self-start, a configuration for accurately detecting the stop crank angle including the engine swing-back phenomenon immediately before the engine is stopped, That is, a sensing system is added that can detect forward / reverse rotation and detect whether or not the rotational speed is zero.

  Thus, according to the technique of Patent Document 1, a complicated sensing system that adds a brake mechanism, detects forward / reverse rotation of the engine, and detects whether or not the rotational speed becomes zero is added. And the time until self-starting becomes long (self-starting becomes slow).

  Therefore, the present invention provides an engine starter that can reliably fit the piston stop position of a start start cylinder within a self-startable range without requiring an additional mechanism or an additional sensing system. Objective.

  The present invention includes fuel supply means for directly injecting and supplying fuel into a combustion chamber, and spark ignition execution means for performing spark ignition on an air-fuel mixture in the combustion chamber, and using these means, an expansion stroke is performed after the engine is stopped. In the engine starter that restarts the engine without the help of the starter motor by injecting fuel into the cylinders at the same time and performing spark ignition, the engine can self-start the crankshaft stop position. Combustion chamber pressure adjusting means for adjusting the combustion chamber pressure when the engine is stopped is provided.

  According to the present invention, the starter motor is assisted by using the fuel supply means and the spark ignition execution means to inject and supply fuel to the cylinders in the expansion stroke after the engine stops and to execute the spark ignition. In the engine starter that restarts the engine without any change, the combustion chamber pressure at the time of engine stop is adjusted so that the engine keeps the crankshaft stop position within the self-startable range. It is not necessary to add a complicated sensing system that can provide a brake mechanism, detect forward / reverse rotation of the engine, and detect whether the rotational speed has become zero, and the time until self-starting An optimal ignition start position can always be obtained in the start-start cylinder without being long (self-start is delayed).

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of an engine according to an embodiment of the present invention, FIG. 2 is a schematic plan view of the engine, and FIG. 3 is a control block diagram of the engine control system. The engine here is a V type 6 cylinder direct injection gasoline engine.

  1 and 2, reference numeral 1 denotes an engine body having left and right banks 1A and 1B. An upstream side of the intake passage 3 includes an electric throttle device 2 including a throttle valve 2a and a throttle motor 2b. The throttle motor 2b receives the throttle motor control signal from the engine controller 21 and drives the throttle valve 2a to open and close. The intake air metered by the butterfly throttle valve 2a is temporarily stored in the intake manifold collector 4 via the intake passage 3, and from the collector 4 through the intake manifold 5 to the cylinders belonging to one bank 1A. It flows into the combustion chamber 6A and into the combustion chamber 6B of each cylinder belonging to the other bank 1B.

  Fuel injection valves 7A and 7B (fuel supply means) and spark plugs 8A and 8B (spark ignition execution means) are provided for each cylinder facing the combustion chambers 6A and 6B. The fuel injection valves 7A and 7B are opened at a predetermined time by a fuel injection signal from the engine controller 21, and fuel is supplied to each combustion chamber 6A of the cylinder belonging to one bank 1A or to each combustion chamber of the cylinder belonging to the other bank 1B. The spark plugs 8A and 8B are injected directly into the 6B, and the spark plugs 8A and 8B are supplied to the air-fuel mixture in the combustion chambers 6A of the cylinders belonging to one bank 1A at the predetermined timing by the ignition signal from the engine controller 21 Spark ignition is performed on the air-fuel mixture in the combustion chambers 6B of the cylinders belonging to the bank 1B.

  The air flowing into the combustion chambers 6A and 6B is vaporized while being mixed with the fuel spray from the fuel injection valves 7A and 7B to form a combustible air-fuel mixture, which is burned by the spark plugs 8A and 8B. It expands and the pressure in each combustion chamber 6A, 6B is rapidly increased. In response to this sudden increase in pressure, the pistons 10A and 10B that reciprocate in the cylinders 9A and 9B of each cylinder descend, and the linear motions of these pistons 10A and 10B are equalized via the connecting rods 11A and 11B, respectively. It is converted into the rotational motion of the crankshaft 12 of the book.

  A crank pulley 13 connected to the crankshaft 12 can be seen on the lower side as shown in FIG. Cylinder numbers are assigned to six cylinders as one cylinder. In this embodiment, the ignition order of the six cylinders is No. 1-No. 2-No. 3-No. 4-No. 5-No. Since the order is 6, each of the six cylinders reaches each stroke as shown in FIG.

  The burned gas is discharged into the exhaust pipes 14A and 14B when the exhaust valves of the respective cylinders are opened at a predetermined timing. Each exhaust pipe 14A, 14B is provided with two catalysts 15A, 15B, 16A, 16B in series, and the exhaust pipes downstream of the two catalysts are grouped downstream.

  As shown in FIG. 3, the signal from the POS sensor (position sensor) 22, the PHASE sensor (phase sensor) 23, the signal of the intake air flow rate from the air flow meter 24, and the signal of the engine cooling water temperature from the water temperature sensor 25 are The signal is input together with a signal from an ignition switch (not shown), an accelerator opening signal from the accelerator sensor 26, a signal indicating whether or not the brake pedal is operated from the brake sensor 27, and a vehicle speed signal from the vehicle speed sensor 28. Based on these signals, the engine controller 21 controls the throttle opening (the opening of the throttle valve 2a), the fuel injection control for each cylinder through the fuel injection valves 7A and 7B, and the ignition plugs 8A and 8B. Ignition timing control for every cylinder. In the control of the throttle valve opening, the target intake air amount is calculated based on the accelerator opening and the engine speed, the target throttle opening is calculated based on the target intake air amount, and the target throttle opening is obtained. As a result, the throttle motor 2b is driven. In fuel injection control, the operating conditions (determined from the engine load and rotation speed) are in the stratified combustion zone or the homogeneous combustion zone (provided on the higher load side or higher rotation side than the stratified combustion zone) after engine startup. When the operating condition is in the stratified combustion region, fuel is injected into the combustion chamber in the compression stroke using the fuel injection valves 7A and 7B, and the fuel spray from the injected fuel injection valve The mixture is used to guide the spark plugs 8A and 8B while making the air-fuel mixture, and the fuel injection timing and the gas flow are controlled so as to be in the vicinity of the spark plugs 8A and 8B at the ignition timing (combustion combustion). The air-fuel ratio of the entire combustion chamber is leaner than the stoichiometric air-fuel ratio, and when the operating conditions are in the homogeneous combustion zone, the entire combustion chamber is filled with a homogeneous mixture and the air-fuel ratio is the stoichiometric air-fuel ratio. Each such that a ratio for controlling the fuel injection amount and fuel injection timing.

  A vehicle having an engine capable of performing such stratified combustion has a function of automatically stopping and restarting the engine incorporated in the engine controller 21. This will be described with reference to FIG. 5. FIG. 5 shows the brake command (detection signal of the brake sensor 27), vehicle speed, engine speed, and throttle opening degree from the automatic stop of the vehicle to the standby state for restart. It shows how it changes. When the driver removes his / her foot from the accelerator pedal for deceleration of the vehicle at t1, the throttle valve 2a is returned in conjunction with this, and the throttle valve 2a is returned to the initial position at the timing of t2 (the throttle opening is zero). Even when the throttle opening becomes zero, the intake air amount that can maintain the rotational speed during idling actually flows through the gap of the throttle valve 2a.

  When the brake pedal is depressed at the timing t3, the brake command is switched from OFF to ON, and both the vehicle speed and the rotational speed are decreased from the timing t4 slightly delayed (deceleration state). At t5, the vehicle stops (the vehicle speed is zero) and the engine is in an idle state. Since the engine controller 21 knows that the vehicle has been stopped based on the signal from the brake sensor 27 and the vehicle speed signal from the vehicle speed sensor 28, the timing is t6 when a predetermined time T1 has elapsed from the timing t5. In order to automatically stop the engine, the engine controller 21 stops all fuel injection by the fuel injection valves 7A and 7B and stops all spark ignition by the spark plugs 8A and 8B. As a result, the engine speed decreases toward zero from the timing of t6, and is zero at the timing of t7, that is, the engine is stopped.

  When the driver releases the brake pedal to restart the vehicle at the timing of t8 after the automatic engine stop, the brake command is switched from ON to OFF. In response to this, the engine controller 21 enters an operation of automatic engine restart. That is, the fuel injection for each cylinder by the fuel injection valves 7A and 7B is restarted at the timing t9 when the predetermined time T2 has elapsed from the timing t8 when the brake pedal is released, and the spark for each cylinder by the spark plugs 8A and 8B. Ignition and restart the engine. When the engine is restarted, the engine settles into an idle state at timing t10.

  In FIG. 5, the throttle valve 2a is opened in the range from t6 to t8, which is a part according to the present invention and will be described later. In the conventional engine, the throttle opening is zero in the range from t6 to t8.

  As described above, in an engine having a function of automatically stopping and restarting the engine, if the crankshaft 12 is cranked using the starter motor every time the engine is restarted, the frequency of use of the starter motor becomes extremely high. In other words, there is a problem that the battery power consumption increases due to frequent current supply to the starter motor. Therefore, a so-called ignition start engine that attempts to start the engine without the starter motor has been proposed. Open 2002-39038). In the prior art in this ignition start engine, the piston position of the start start cylinder (for example, the first cylinder) when the engine is stopped in the 4-cylinder serial injection engine is within a range from 5 ° after top dead center to 110 ° after top dead center, that is, By stopping the engine within the self-startable range and igniting after the fuel injection valve injects fuel according to the amount of intake air in the combustion chamber when starting the engine. I try to start it.

  However, since the piston stop position of the start start cylinder generally varies widely, the prior art in such an ignition start engine cannot always stop the piston stop position of the start start cylinder within a self-startable range. I am devised like this.

  (1) A mechanical brake mechanism is provided to stop the crankshaft 12 at a position where the self-start can be performed when the engine is stopped, and the piston stop position of the start cylinder can be mechanically self-started by this brake mechanism. Stop within the range (10 ° -140 ° after top dead center).

  (2) A starter motor is provided in the same manner as the conventional engine, and when the piston stop position of the start start cylinder does not fall within the self-startable range, the start stop motor can self-start the piston stop position of the start start cylinder. Move into range.

  (3) Since it is necessary to calculate the fuel injection amount according to the amount of intake air in the combustion chamber of the start cylinder at the time of self-start, a configuration for accurately detecting the stop crank angle including the engine swing-back phenomenon immediately before the engine is stopped, That is, a sensing system is added that enables detection of forward / reverse whether the engine is rotating forward or reverse and whether the rotational speed is zero.

  However, it is expensive to provide the brake mechanism (1) or add a complicated sensing system as described in (3). Further, according to the configuration (2), the time until self-starting becomes long (self-starting becomes slow), so that drivability is deteriorated, sound vibration performance is deteriorated, and cost is increased.

  Therefore, the present inventor tried to change the way of thinking with respect to the conventional way of thinking in an ignition start engine. In other words, since the piston stop position (= stop position of the crankshaft 12) of the start start cylinder has a large variation in the first place, an operation for keeping the piston stop position of the start start cylinder within the self-startable range is necessary. If there is, the idea is that the piston stop position of the start cylinder can be kept within the self-startable range. Based on this idea, the piston stop position of the starting cylinder is determined by the pressure balance acting on the crankshaft 12, and the factor affecting this pressure balance is mainly the pressure in the combustion chamber with the intake and exhaust valves closed. As a result, various experiments were conducted by changing the pressure in the combustion chamber with the intake and exhaust valves closed, and after the engine stop command was received and the fuel injection and spark ignition were stopped, the engine rotated by inertia. In the meantime, by introducing the atmospheric pressure to the combustion chambers 6A and 6B, the piston stop position of the start-start cylinder was successfully kept within the range where self-start was possible.

  FIG. 6 shows the experimental results obtained by the present inventors. In FIG. 6, the horizontal axis indicates the piston stop position (= stop position of the crankshaft 12) of the start cylinder, and the vertical axis indicates frequency. In the case of a conventional engine (indicated by “no V6 device” in the figure), the piston stop position of the starting cylinder varies in a wide range from 40 ° after top dead center to 90 ° after top dead center as shown by the broken line. On the other hand, after applying the present invention to stop the fuel injection and spark ignition upon receiving the engine stop command, the atmospheric pressure is induced in the combustion chambers 6A and 6B while the engine is rotating by inertia. In the case of the engine (described with “with V6 device” in the figure), as shown by the solid line, the piston stop position of the starting cylinder is very narrow from 50 ° after top dead center to 65 ° after top dead center. It can be seen that almost all are stopped in the range.

  The reason for this is that the intake pressure downstream of the throttle valve 2a is brought close to atmospheric pressure (induced to atmospheric pressure), and the pump work of each piston 10A, 10B in the compression stroke and expansion stroke is increased to increase the compression stroke and expansion stroke. The reaction force of each of the pistons 10A and 10B is increased, and the increased reaction force seems to narrow the range of variation in the piston stop position of the start cylinder.

  In this way, when an engine in which the piston stop position of the starting cylinder remains within the self-startable range is provided, the brake mechanism (1) is provided as in the prior art in the ignition starting engine, It is not necessary to add a complicated sensing system as in (3). In addition, as described in (2) above, the time until self-starting is not prolonged (self-starting is delayed). This is because, according to the present invention, the piston stop position of the start-start cylinder is within a range in which the engine can be started by the action of the engine itself without any action when the engine is stopped or after the engine is stopped. To stay in.

  In FIG. 4, the start start cylinder may be any of the six cylinders. Assuming that one cylinder is a start start cylinder, self-start is performed by performing fuel injection from the fuel injection valve and spark ignition by the spark plug in the expansion stroke of the start start cylinder. In this case, no. The expansion stroke of one cylinder and the next cylinder No. No. 4 cylinder compression stroke overlaps in the entire range. No. 1 cylinder expansion stroke, 2-cylinder, no. 3 cylinder, no. 5-cylinder and no. The compression strokes of the six cylinders overlap in a certain range. Therefore, no. In order for self-starting to be performed with the torque generated by one cylinder, no. The generated torque of one cylinder needs to be larger than the sum of the compression torques of the remaining five cylinders (No. 2 cylinder to No. 6 cylinder). If this condition is not satisfied, no. When the generated torque of one cylinder (starting cylinder) is smaller than the total compression torque of the remaining five cylinders (No. 2 cylinder to No. 6 cylinder) (or the generated torque of the No. 1 cylinder remains 5 cylinders) In order to ensure that it is greater than the total compression torque of No. 2002-39038), a known method disclosed in Japanese Patent Application Laid-Open No. 2002-39038 is used. Measures may be taken so that the generated torque of one cylinder (starting start cylinder) becomes larger than the total compression torque of the remaining five cylinders (No. 2 cylinder to No. 6 cylinder). Since the present invention relates to the piston stop position of the start start cylinder, the relationship between the generated torque of the start start cylinder and the compression torque of the next cylinder is out of scope and will not be described. Therefore, in the present invention, if fuel injection supply and spark ignition are performed on the start start cylinder in the expansion stroke, the self start is always performed by the torque generated by the start start cylinder.

  In order to induce atmospheric pressure to the combustion chambers 6A and 6B, the engine control unit 21 that satisfies the engine automatic stop condition and receives the engine automatic stop command performs the fuel injection supply by the fuel injection valves 7A and 7B and the spark plug 8A, After the spark ignition by 8B is interrupted, the throttle valve 2a provided in the upstream position of the intake passage 3 may be opened during the engine rotation until the engine stops due to inertia due to inertia. Returning to FIG. 5, since the inertial rotation until the engine stops is a period from t6 to t7, during the period from t6 to t7, the throttle valve 2a is set as shown in the fourth stage of FIG. For example, it opens from the fully closed position to the fully open position.

  However, the opening method of the throttle valve 2a performed during inertial rotation (period t6 to t7) until the engine stop shown in the fourth stage in FIG. 5 is not limited to this, and various modes are conceivable. . This is collectively shown in FIG. FIG. 7 shows the engine rotation speed and the throttle opening during inertial rotation until the engine stop in FIG. 5 and shows the same timing as in FIG. More specifically, FIG. 7B shows the throttle opening from the fully closed position to the fully opened position at t6, which is the engine rotation stop start timing, and FIG. 7C shows t6, which is the engine rotation stop start timing. The throttle opening is increased stepwise from a fully closed position to a predetermined opening that is not fully open.

  On the other hand, FIG. 7D shows that the throttle opening is increased at a constant speed from t6, which is the engine rotation stop start timing, and the fully open position is t7, which is the engine stop timing at which the engine rotation speed becomes zero. FIG. 7E shows the engine stop timing t7 when the engine rotation speed becomes zero by gradually increasing the throttle opening at a constant speed from t6 that is the engine rotation stop start timing. Thus, a predetermined opening which is not the fully open position is reached. When the throttle opening is increased stepwise, that is, when the throttle valve 2a is suddenly opened, the pump work changes greatly before and after the valve is opened to increase engine vibration, or intake air generated when the throttle valve 2a is opened. Although the sound becomes louder, by gradually increasing the throttle opening from zero in this way, engine vibration due to pumping work can be reduced compared to opening the throttle valve 2a suddenly, and the throttle valve 2a is opened. Intake air sound generated at the time can be reduced.

  The throttle valve 2a may be opened in a range from t6 (when fuel injection and spark ignition are stopped) to t7 (when the engine is completely stopped), and therefore the throttle valve 2a is shown in FIGS. 7 (d) and 7 (e). As shown in FIG. 7 (f), the timing for increasing the throttle opening is the timing immediately before the engine stop timing t7, as shown in FIG. 7 (f). Delay until t11 (predetermined time T3 before the time when the engine is completely stopped) so that the fully open position is reached at t7 which is the engine stop timing, and the throttle opening is increased as shown in FIG. 7 (g). Is delayed until t11, which is a timing immediately before the engine stop timing t8, and becomes a predetermined opening that is not the fully open position at the engine stop timing t7. It can be so.

  Next, engine automatic stop / restart control executed by the engine controller 21 will be described with reference to the flowchart of FIG. The flow of FIG. 8 shows a time-series procedure. However, the throttle valve 2a is assumed to be opened stepwise from the fully closed position to the fully open position at a predetermined timing (t6) as shown in FIG. 7B.

  In step 1, it is checked whether or not the vehicle speed detected by the vehicle speed sensor 28 is zero. If the vehicle speed is not zero, the vehicle has not stopped, so it waits as it is.

  If the vehicle speed is zero, the process proceeds to step 2 to see if the brake pedal is depressed. When the brake pedal is not depressed, the brake sensor 27 is OFF, and when the brake pedal is depressed, the brake sensor 27 is turned ON. Therefore, if the brake pedal is not depressed, it is determined that the vehicle has not stopped reliably and the process returns to step 1.

  When the brake pedal is depressed, the routine proceeds from step 2 to step 3, and a certain time T1 (see FIG. 5) has elapsed since the vehicle is in a state of being almost stopped (after satisfying the requirements of steps 1 and 2). See if you are doing it. If the predetermined time T1 has not elapsed, it is determined that the vehicle has not stopped reliably, and the process returns to step 1.

  If the predetermined time T1 has elapsed since the vehicle is almost stopped, it is determined that the vehicle has stopped reliably, and the process proceeds from step 3 to steps 4 and 5, and the operations in steps 4 and 5 are performed. Let them be done at the same time. That is, all fuel injections from the fuel injection valves 7A and 7B are interrupted, and all spark ignition by the spark plugs 8A and 8B is cut. As a result, the engine does not generate torque, and the engine turns to inertia while rotating by inertia.

  In step 6, the throttle valve 2a is opened stepwise to the fully open position by an operation performed almost simultaneously with the operations of steps 4 and 5. As a result, the intake air at substantially atmospheric pressure is introduced (guided) into the combustion chambers 6A and 6B of each cylinder while the engine rotation is rotating inertially and toward the engine stop state.

  In the following step 7, it is determined whether or not the engine has stopped based on signals from the crank angle sensors (22, 23). If the engine is not stopped, it waits as it is. If the engine stops before long, the routine proceeds from step 7 to step 8 to see if the brake pedal is depressed. If the brake pedal is still depressed, it waits as it is.

  In this case, in the present invention, since the “function to keep the stop position of the crankshaft 12 within a self-startable range” is given to the engine, the piston of the starting cylinder (for example, No. 1 cylinder) is operated by the engine itself. The stop position remains within a range where self-starting is possible.

  When the brake pedal is released, it is predicted that the vehicle will start, and the routine proceeds to step 9, where the throttle valve 2a is returned to the initial position (fully closed position) stepwise.

  In Step 10, it is checked whether or not a certain time T2 (see FIG. 5) has elapsed since the release of the brake pedal (after satisfying the requirements of Step 8). If the predetermined time T2 has not elapsed, the process waits as it is.

  If the predetermined time T2 has elapsed since the release of the brake pedal, the process proceeds to steps 11 and 12, and the operations of steps 11 and 12 are performed simultaneously. That is, fuel injection from the fuel injection valves 7A and 7B is resumed, and spark ignition is performed by the spark plugs 8A and 8B. This restarts the engine and prepares for vehicle start.

  Here, according to the present invention, the piston stop position of the start start cylinder remains in a narrow range within the self-startable range as shown in FIG. 6, and therefore, the start start cylinder from the piston stop position of the start start cylinder. The amount of intake air in the combustion chamber can be known in advance. That is, unlike the prior art in the ignition start engine, it is not necessary to calculate the fuel injection amount according to the intake air amount of the combustion start cylinder in the start start cylinder at the time of self start. What is necessary is just to give the fuel injection amount of a fixed value.

  Here, the effect of this embodiment is demonstrated.

  According to this embodiment (the invention described in claim 1), the fuel injection valves 7A and 7B (fuel supply means) for directly injecting fuel into the combustion chambers 6A and 6B, and the combustion chambers 6A and 6B Spark plugs 8A and 8B (spark ignition execution means) for spark-igniting the air-fuel mixture, and using these fuel injection valves 7A and 7B and spark plugs 8A and 8B, the cylinders in the expansion stroke after the engine is stopped In an engine starter that restarts the engine without the help of a starter motor by injecting fuel and performing spark ignition so that the engine keeps the stop position of the crankshaft 12 within a self-startable range. Is provided with combustion chamber pressure adjusting means for adjusting the combustion chamber pressure when the engine is stopped (see steps 4, 5, and 6 in FIG. 6). Thus, it is not necessary to add a complicated sensing system that can detect the forward / reverse rotation of the engine and whether or not the rotational speed becomes zero, and to provide self-starting. An optimal ignition start position can always be obtained in the start-up cylinder without increasing the time (self-starting is delayed).

  According to the present embodiment (the invention described in claim 2), the combustion chamber pressure adjusting means is a throttle valve 2a that is controlled to a fully closed position at the time of idling, and a fuel by the fuel injection valves 7A and 7B in response to an engine stop command. After stopping the spark ignition by the injection and spark plugs 8A, 8B, the throttle valve 2a is opened (see steps 4, 5, and 6 in FIG. 6) while the engine is rotating by inertia. And the atmospheric pressure induction means for inducing the intake pressure to the atmospheric pressure, the pump work of the pistons 10A and 10B in the compression stroke and the expansion stroke becomes large, and the reaction force of the pistons 10A and 10B in the compression stroke and expansion steps The range of variation in the stop position of the crankshaft 12 can be narrowed. This improves the starting rate of the ignition start engine.

  FIG. 9 shows a schematic configuration diagram of an intake system of the second embodiment. In the second embodiment, an auxiliary air passage 31 that bypasses the throttle valve 2 a is provided, and an electromagnetic valve (intake flow control valve) 32 that can variably control the opening area of the auxiliary air passage 31 is interposed in the auxiliary air passage 31. The electromagnetic valve 32 causes a change similar to the change in each throttle opening shown in FIGS. 7B to 7G. That is, in FIG. 7B to FIG. 7G, the vertical axis represents the throttle opening, but the second embodiment may be applied by replacing the vertical axis with the opening area of the electromagnetic valve 32. For example, when the change in the opening area of the electromagnetic valve 32 corresponding to the change in the throttle opening shown in FIG. 7 (c) is shown in FIG. 10 (a), the electromagnetic valve at the timing t6, which is the engine rotation stop start timing. The opening area of the flow control valve 32 is switched stepwise from state 1 to state 2. Here, the state 1 is a state where the opening area of the electromagnetic valve 32 is zero (minimum value) as shown on the left side of FIG. 10B, and the state 2 is a flow rate control as shown on the right side of FIG. 10B. This is a state in which the opening area of the valve 32 is at a predetermined value (for example, a maximum value) that is not zero.

  In this way, the second embodiment can achieve the same operational effects as the first embodiment.

  In the second embodiment, the electromagnetic valve 32 is provided in the auxiliary air passage 31, but is not limited thereto. For example, a butterfly-type second throttle valve is provided in place of the electromagnetic valve, and each throttle opening shown in FIGS. 7B to 7G is changed by the second throttle valve. It doesn't matter. At this time, for example, state 1 and state 2 shown in FIG. 10A are as shown in FIG. Further, a mechanical valve may be used instead of the electromagnetic valve.

  In the embodiment, only the V-type 6-cylinder direct injection engine is examined, but the V-type 8-cylinder direct-injection engine and the in-line direct-injection engine are not examined. However, it seems to be applicable to V-type 8-cylinder direct injection engines and in-line direct injection engines.

1 is a schematic configuration diagram of an engine according to a first embodiment of the present invention. FIG. The control block diagram of an engine control system. The stroke diagram of a V type 6 cylinder engine. The wave form diagram which shows the motion from the automatic stop of a vehicle to the standby state for a re-start. The characteristic view which shows frequency distribution with respect to the stop position of a crankshaft. The wave form diagram which shows the valve-opening method of the throttle valve performed during inertial rotation until an engine stop. The flowchart for demonstrating control of an engine automatic stop and restart. The schematic block diagram of the intake system of 2nd Embodiment. The wave form diagram which shows the valve opening method of the throttle valve performed during inertial rotation until the engine stop of 2nd Embodiment.

Explanation of symbols

1 Engine body 2a Throttle valve 6A, 6B Combustion chamber 7A, 7B Fuel injection valve (fuel supply means)
8A, 8B Spark plug (spark ignition execution means)
12 Crankshaft 21 Engine controller

Claims (8)

Fuel supply means for directly injecting and supplying fuel into the combustion chamber;
Spark ignition executing means for performing spark ignition on the air-fuel mixture in the combustion chamber,
In the engine starting device for restarting the engine without the help of the starter motor by injecting fuel to the cylinder in the expansion stroke after stopping the engine using these means and executing spark ignition,
An engine starting device comprising combustion chamber pressure adjusting means for adjusting a combustion chamber pressure when the engine is stopped so as to keep a stop position of the crankshaft within a range where self-starting is possible. The combustion chamber pressure adjusting means includes
A throttle valve that is controlled to a fully closed position during idling,
And an atmospheric pressure guiding means for guiding the intake pressure downstream of the throttle valve to the atmospheric pressure while the engine is coasting and rotating after stopping the fuel injection and spark ignition in response to the engine stop command. The engine starting device according to claim 1.   3. The engine starting device according to claim 2, wherein the atmospheric pressure guiding means is valve opening means for opening the throttle valve from the fully closed position. An auxiliary air passage that bypasses the throttle valve;
An intake flow control valve capable of adjusting the area of opening the auxiliary air passage,
The engine starter according to claim 2, wherein the atmospheric pressure guiding means is a valve opening means for opening the intake flow rate control valve.   4. The engine starting device according to claim 3, wherein the throttle valve is opened in a range from a time point when the fuel injection and spark ignition are stopped to a time point when the engine is completely stopped.   The engine starter according to claim 4, wherein the intake flow rate control valve is opened in a range from a time point when the fuel injection and spark ignition are stopped to a time point when the engine is completely stopped.   6. The engine starting device according to claim 5, wherein the throttle valve is opened stepwise when the fuel injection and spark ignition are stopped.   The engine starter according to claim 6, wherein the intake flow control valve is opened stepwise when the fuel injection and spark ignition are stopped.