JP2005248967A - Stop/start control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restore an internal combustion engine to a drive state without generating delay to a request for start immediately after determination of stop in an internal combustion engine under economy-running control. <P>SOLUTION: Prescribed stop control is executed including control to stop supply of fuel to the internal combustion engine as predetermined stop conditions are satisfied, and start control is executed including control to restart supply of fuel to the internal combustion engine as predetermined start conditions are satisfied in this stop/start control device for an internal combustion engine. A stop control canceling means (step S15) is provided to cancel the stop control in a case where the start conditions are satisfied within a predetermined period after the stop conditions are satisfied and before the internal combustion engine is stopped. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device that automatically stops and starts an internal combustion engine such as a diesel engine or a gasoline engine when a predetermined condition is satisfied.

  Based on demands such as reduction of exhaust gas and improvement of fuel consumption, it is encouraged to stop the engine as much as possible when the vehicle is temporarily stopped and the engine is idling. In this case, the engine is stopped and then restarted, and the driver manually operates the main switch or the ignition switch, and may not be sufficiently driven. Therefore, a control for automatically performing this kind of automatic stop and restart has been developed, and this is so-called eco-run control.

One example thereof is described in Patent Document 1. The device described in this publication is configured to automatically stop and start the engine automatically in a shift state in which the shift lever is set to a travel position such as the D position and torque appears on the output shaft of the transmission. ing. More specifically, the vehicle speed is below a predetermined value close to zero, the foot brake is depressed (ON), the accelerator pedal is released (accelerator OFF), etc. When the stop condition is established, a command to stop the fuel supply to the engine is output. Thereafter, when a starting condition such as depression of the accelerator pedal or return of the brake pedal is satisfied, a command for restarting the engine is output.
JP 2001-88580 A

  This type of eco-run control (or D-range eco-run control) is a control that stops the engine when the vehicle is temporarily stopped by a stop signal or the like in the course of traveling to a predetermined destination. It is required to restart the engine without causing a delay with respect to the start. However, since various types of control are involved from the start of engine stop control until it can be restarted, the conventional control causes a delay in restart, which causes a so-called feeling of stickiness. was there.

  That is, when the engine is stopped, if the supply of fuel is simply stopped, torque is generated at the compression pressure while the engine rotates with inertial force, and as a result, vibration may occur. Such a situation is likely to occur in a diesel engine that performs high-pressure compression. Therefore, in order to smoothly stop the engine rotation, the intake throttle valve and EGR valve (valve for recirculating exhaust gas to the intake side) are closed to throttle the intake air and reduce the amount of air into the cylinder. The actual compression ratio is lowered, and then the fuel supply is stopped.

  Further, even if the supply of fuel is stopped, the rotation of the engine does not stop immediately, but continues to rotate with inertial force, and the rotation speed gradually decreases and finally stops. In order to restart the engine thereafter, cranking that forcibly rotates the engine is required. If this is done with a gear-type starter, the gear can be meshed with the rotation stopped, so the engine stop is judged before meshing the starter-side gear with the engine-side gear. There is a need.

  The stop determination is made based on an electric signal such as a pulse signal obtained by rotation of a rotating shaft such as a crankshaft, for example, but the state of the signal due to the engine stopping and the engine speed are temporarily determined. Since it is necessary to determine the state of the signal due to the decrease, the stop state is determined when the signal state continues for a predetermined time. That is, it takes a certain amount of time to determine whether or not to stop the engine in order to prevent erroneous determination.

  In this way, after it is determined that the engine has been stopped, the starter is operated, and start control such as restarting fuel injection is executed. Therefore, after the stop condition is satisfied, preparatory control for stopping the engine, such as reducing the intake air, is performed, and the fuel supply is stopped to decrease the engine speed, and finally wait for the stop, and then stop. When the time for determination elapses, the engine is restarted.

  Conventionally, when a gear-type starter is used, in order to smoothly engage the gear, the engine is restarted after the engine stop determination is established as described above. Therefore, even if the restart condition such as the accelerator pedal being depressed immediately after the engine stop condition in the eco-run control is satisfied (when the restart is requested), the restart condition After the establishment, the engine start control is executed after the elapse of time for the so-called preparation control and engine stop determination described above, and therefore, the response delay of the engine restart becomes remarkable. After all, conventionally, the responsiveness of the restart is not always good, and when there is a request for restart of the engine immediately after the establishment of the stop condition, there is a possibility that the so-called feeling of stickiness becomes remarkable.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a control device capable of improving the restart responsiveness of an automatically stopped internal combustion engine.

  In order to achieve the above-described object, the present invention provides an internal combustion engine in which a restart request is made during a predetermined state before the internal combustion engine is completely started even when the internal combustion engine stop condition is satisfied. The engine stop control is stopped, and the internal combustion engine is continuously operated without being stopped. More specifically, the invention of claim 1 executes predetermined stop control including control for stopping the supply of fuel to the internal combustion engine when a predetermined stop condition is satisfied, and the predetermined start condition is In a stop / start control device for an internal combustion engine that executes start control including control for resuming fuel supply to the internal combustion engine when established, a predetermined period after the stop condition is satisfied and before the internal combustion engine is stopped And a stop control stopping means for stopping the stop control when the start condition is satisfied.

  According to a second aspect of the present invention, the predetermined period in the first aspect is a period in which stop preparation control is executed prior to stopping the fuel supply and reducing the rotational speed of the internal combustion engine. Is a control device characterized by

  Further, the invention according to claim 3 is characterized in that the stop control stop means according to claim 2 includes return control means for executing return control for returning the internal combustion engine to a predetermined operation state in which self-sustaining rotation is maintained. It is a control device.

  Still further, the invention of claim 4 further comprises restart means for executing start control for starting the internal combustion engine when the internal combustion engine is stopped even if the stop control is stopped. It is the control device characterized by comprising.

  The invention according to claim 5 is the invention according to claim 1, wherein the opening of the flow rate adjustment valve on the intake side, in which the opening is reduced before the fuel supply is stopped, is determined in advance. It is a control device characterized in that it is a period until it drops to a predetermined opening degree.

  On the other hand, according to a sixth aspect of the present invention, in the first aspect, the predetermined period is a period from when the fuel supply is stopped until the rotational speed of the internal combustion engine decreases to the predetermined rotational speed. It is the control apparatus characterized by the above.

  The invention according to claim 7 is the invention according to claim 6, wherein the stop control stopping means increases the opening of the intake side flow rate adjustment valve that has been reduced in opening prior to stopping the fuel supply. A control device configured to execute control for resuming fuel supply.

  Further, the invention of claim 8 is the invention according to claim 7, wherein the rotational speed of the internal combustion engine at the time when the stop control stopping means increases the opening of the intake side flow regulating valve to a predetermined opening is set in advance. The control device is configured to restart the supply of fuel when a predetermined number of revolutions is exceeded.

  According to the first aspect of the present invention, after the condition for stopping the internal combustion engine is established, the accompanying control is started, and the internal combustion engine is started for a predetermined period before the internal combustion engine stops. When the condition is satisfied, the stop control for stopping the internal combustion engine is stopped, so that the internal combustion engine continues to rotate without stopping, and thus a time delay is particularly caused with respect to the satisfaction of the start condition. Therefore, the internal combustion engine is in a driving state, and it is possible to avoid a delay in response of control for starting the internal combustion engine and a so-called feeling of stickiness caused by the response.

  According to the invention of claim 2, although the rotational speed of the internal combustion engine is reduced, the stop control is stopped when the start condition is satisfied while the internal combustion engine is rotating. The engine continuously rotates without stopping, and as a result, the internal combustion engine is in a driving state without causing a time delay with respect to the establishment of the start condition, and the response delay of the control for starting the internal combustion engine or the cause thereof It is possible to avoid the so-called feeling of stickiness.

  Further, according to the invention of claim 3, the same effect as that of the invention of claim 2 can be obtained, and in addition, when the stop control of the internal combustion engine is stopped, the internal combustion engine that has changed by the control up to that point is changed. Since the return control for returning the engine operating state to the state before the start of the stop control is executed, the self-sustaining rotation of the internal combustion engine can be reliably maintained.

  Further, according to the invention of claim 4, the same effect as that of the invention of claim 1 or 2 can be obtained, and the internal combustion engine stop control can be stopped even if the internal combustion engine is stopped while it is rotating. When the engine is stopped, the internal combustion engine is immediately restarted, so that the internal combustion engine is started quickly according to the establishment of the start condition, and as a result, a response delay in the start control is avoided or suppressed. can do.

  According to the fifth aspect of the invention, the same effect as that of the first aspect of the invention can be obtained, and while the opening degree of the flow regulating valve on the intake side is reduced to a predetermined opening degree while supplying fuel. When the start condition is satisfied, the stop control of the internal combustion engine is stopped. Therefore, when the intake of the internal combustion engine is not stopped, the further stop control is stopped, and as a result, the rotation of the internal combustion engine may be continued. Therefore, it is possible to improve the responsiveness of the control for setting the internal combustion engine in the operating state based on the establishment of the start condition.

  On the other hand, according to the invention of claim 6, the same effect as that of the invention of claim 1 can be obtained, and the stop control is executed in accordance with the establishment of the stop condition, and the fuel supply to the internal combustion engine is stopped. Even after this, if the rotational speed of the internal combustion engine is equal to or higher than the predetermined rotational speed, the stop control of the internal combustion engine is stopped, so that the internal combustion engine rotates independently by restarting the supply of fuel to the internal combustion engine, etc. As a result, even after the stop control of the internal combustion engine is started due to the establishment of the stop condition, the opportunity to immediately independently rotate the internal combustion engine with the establishment of the start condition can be increased.

  Further, according to the invention of claim 7, the same effect as that of the invention of claim 6 can be obtained, and when the stop control of the internal combustion engine is stopped, the supply of the already stopped fuel is resumed prior to restarting the supply. Thus, the opening degree of the intake side flow rate adjustment valve is increased, so that the internal combustion engine can be reliably or smoothly rotated independently.

  According to the invention of claim 8, the same effect as that of the invention of claim 7 can be obtained, and when the supply of fuel to the internal combustion engine is resumed when the stop control is stopped, this is executed prior to that. Since the supply of fuel is resumed on condition that the rotation speed at the time when the opening of the flow regulating valve on the intake side is increased is equal to or higher than the predetermined rotation speed, the internal combustion engine under stop control is reliably rotated independently. be able to.

  Next, the present invention will be described based on specific examples. First, an internal combustion engine that is an object of the present invention will be described. The internal combustion engine according to the present invention is an internal combustion engine that can be automatically stopped and automatically restarted by supplying and stopping fuel or air, or by turning ignition on and off. Examples are engines such as diesel engines, gasoline engines, and engines using gas as fuel. FIG. 11 shows a diesel engine as an example of the internal combustion engine (engine) 1, and the example shown here is a so-called direct injection engine that directly injects fuel into the cylinders 2, 3, 4, and 5. An exhaust gas recirculation mechanism for exhaust gas purification is provided.

  That is, each of the cylinders 2, 3, 4, and 5 is provided with injectors 6, 7, 8, and 9 for injecting fuel at a high pressure, and these injectors 6, 7, 8, and 9 provide high-pressure fuel. Is connected to a common rail 10 which is supplied under pressure. Each cylinder 2, 3, 4, 5 is provided with a glow 11, 12, 13, 14 respectively.

  An intake manifold 15 that distributes and supplies intake air to the cylinders 2, 3, 4, and 5 is connected to a compressor 17 in the exhaust supercharger 16. An intake air passage from the compressor 17 to the intake manifold 15 is provided with an intercooler 18 that cools the pressurized intake air whose temperature has risen, and an intake throttle valve 19 that controls the intake air amount. The intake throttle valve 19 is configured to be electrically controlled by an actuator (not shown) such as a motor.

  On the other hand, an exhaust manifold 20 connected to the exhaust port of each cylinder 2, 3, 4, 5 is connected to an exhaust turbine 21 in the supercharger 16. Further, the exhaust turbine 21 is communicated with a catalytic converter 22 provided with an exhaust purification catalyst.

  An exhaust gas recirculation pipe 23 is provided for guiding a part of the combustion exhaust gas generated in each cylinder 2, 3, 4, 5 to the intake manifold 15. The exhaust gas recirculation pipe 23 is provided with an EGR for cooling the exhaust gas. A cooler 24 and an EGR valve 25 that controls the flow rate of the exhaust gas are interposed in the order listed here from the exhaust manifold 20 side. The EGR valve 25 and the intake throttle valve 19 correspond to the intake side flow rate adjusting valve of the present invention.

  The engine 1 is automatically stopped when a predetermined condition such as stopping and being braked is satisfied, and automatically stops when a stop condition such as releasing the braking operation is not satisfied after that. So-called eco-run control can be restarted automatically. An engine electronic control unit (E-ECU) 26 and an eco-run electronic control unit (ECO-ECU) 27 for the control are provided.

  These electronic control units 26 and 27 are configured mainly with a microcomputer, and the engine electronic control unit 26 performs calculation based on the input data to control the operating state of the engine 1. It is configured. Specifically, when a start request is made, a starter (not shown) is driven to mesh the gear with the gear on the engine 1 side, the engine 1 is cranked, and fuel is injected based on the acceleration / deceleration request. The amount is controlled, and the opening degree of the intake throttle valve 19 and the EGR valve 25 is controlled together with the amount if necessary, and further, the supercharging pressure by the supercharger 16 is controlled based on the acceleration / deceleration request. Has been.

  The eco-run electronic control device 27 performs an operation based on the input data, determines whether the stop condition or the start condition of the engine 1 is satisfied, and determines whether the engine electronic control device 26 uses the engine based on the determination result. 1 stop request and start request are output. The stop condition is, for example, that the vehicle speed is determined to be zero and it is determined that the brake is being operated. The start condition is that any of the contents of the stop condition is not satisfied, for example, the brake operation is released. When there is a stop request or a start request, the engine electronic control unit 26 controls the stop or start of the engine 1 according to the request, and when there is no such request, the engine electronic control device 26 sets the accelerator opening. It is configured to control the output (more specifically, the fuel injection amount) of the engine 1 according to the representative drive request amount.

  In order to perform these controls, an accelerator opening sensor 28 and a crank angle sensor 29 are connected to the electronic control unit 26. Although not specifically shown, any appropriate signal such as a vehicle speed signal is input to one of the electronic control devices 26 and 27.

  The crank angle sensor 29 is a sensor that detects a crank angle in order to determine a cylinder that injects fuel. As shown in FIG. 12, an angle plate 30 attached to the output shaft of the engine 1 and an outer peripheral side thereof. And a pickup 31 disposed at a predetermined position. The angle plate 30 is a disk-like or gear-like member having protrusions or teeth formed on the outer peripheral edge at predetermined angles (for example, 10 degrees). On the other hand, the pickup 31 is a so-called electromagnetic pickup, and is configured to output a signal every time the projection or tooth of the angle plate 30 approaches and then leaves.

  In addition, some protrusions or teeth formed on the outer periphery of the angle plate 30 are missing, and the signal at that portion is different from the other portions. Although not specifically shown, a disc having only one protrusion or tooth is attached to another rotating shaft such as a camshaft that rotates once while the crankshaft rotates twice, and the above pickup is mounted on the outer periphery thereof. A pickup similar to 31 is arranged and configured to output a signal in response to a single protrusion or tooth formed on the disk.

  The position of the single protrusion or tooth is related to the position of the predetermined piston (top dead center or bottom dead center). Therefore, the position of the piston in each of the cylinders 2, 3, 4, and 5 is determined based on a signal obtained by rotating the angle plate 30 and the disk or a pulse signal obtained by shaping the signal. The cylinders 2, 3, 4 and 5 to be injected can be discriminated. As a technique for discriminating the angular position of this type of crankshaft and the cylinder that injects fuel based thereon, the technique described in, for example, Japanese Patent Application Laid-Open No. 11-62681 can be employed.

  Next, stop control and restart control of the engine 1 under the so-called eco-run control by the control device of the present invention including the electronic control devices 26 and 27 will be described. FIG. 1 is a flowchart for stop determination executed by the eco-run electronic control device 27, which is repeatedly executed every predetermined short time. In this routine, first, it is determined whether or not the engine 1 is rotating (step S1). If a negative determination is made in step S1 because the engine 1 is stopped, the process returns without performing any particular control.

  On the contrary, if the determination in step S1 is affirmative because the engine 1 is rotating, it is determined whether or not a stop condition for the engine 1 is satisfied (step S2). This determination is performed in a state where the engine 1 is rotating, and the stop condition is established according to the situation of the vehicle on which the engine 1 is mounted. For example, the stop condition is established when the determination that the vehicle speed is zero is established and a braking operation such as depression of the brake pedal is performed.

  If a negative determination is made in step S2, the process returns without performing any particular control. On the other hand, when an affirmative determination is made in step S2, the engine stop request is turned ON (step S3). That is, a stop request for automatically stopping the engine 1 is output to the engine electronic control unit 26.

  FIG. 2 is a flowchart showing an example of engine stop request control executed by the engine electronic control unit 26 based on the engine stop request, and is repeatedly executed every predetermined short time. In this routine, first, it is determined whether or not there has been an engine stop request from the eco-run electronic control device 27 (step S11).

  If the engine 1 has already been stopped or the accelerator pedal has been depressed to some extent and is traveling, the aforementioned stop condition is not satisfied, so a negative determination is made in this step S11. In that case, the process returns without performing any particular control. On the other hand, when an affirmative determination is made in step S11, it is determined whether or not the engine 1 is stopped (step S12).

  As described above, since the output of the engine 1 is normally controlled in accordance with the required drive amount represented by the accelerator opening, etc., the stop condition described above is satisfied, and the determination is positive in step S11. In this case, the engine 1 is idling because the accelerator pedal is returned. However, the engine 1 may stall from an idling state due to some factor such as a mistake in clutch operation of a transmission (not shown). Step S12 is for determining whether such a situation has occurred.

  If the determination in step S12 is affirmative, it is no longer necessary to perform further control for stopping, and the process returns. On the contrary, if a negative determination is made in step S12, that is, if the engine 1 is idling and rotating, it is determined whether or not it is within the preparation period in the stop control of the engine 1 ( Step S13).

  When the engine electronic control device 26 is requested to stop due to the establishment of the stop condition of the engine 1, the engine electronic control device 26 executes stop control of the engine 1 based on so-called eco-run control. In essence, this control is a control for stopping the rotation of the engine 1 by stopping the supply of fuel, and is a control for improving fuel consumption by not performing unnecessary idling. In that case, if the supply of fuel to the rotating engine 1 is suddenly stopped, a high compression force may be generated by intake air or EGR, and torque and vibration may be generated. Such a situation is likely to occur in a diesel engine.

  Therefore, in order to stop the engine 1 smoothly, first, the opening amounts of the intake throttle valve 19 and the EGR valve 25 which are the flow rate adjustment valves on the intake side are reduced, and the amount of air sucked into the cylinders 2, 3, 4 and 5 Is reduced. After the opening of the intake throttle valve 19 and the EGR valve 25 is fully closed, for example, the supply (injection) of fuel to the engine 1 is stopped. Thereafter, although the engine 1 continues to rotate with the inertial force, the rotational speed thereof gradually decreases. In that case, even if the engine 1 rotates after the fuel supply is stopped, since the intake air is cut off, the rotational speed of the engine 1 smoothly decreases.

  The rotational speed of the engine 1 decreases after the fuel supply is stopped, and stops after a predetermined time. The determination of the stop of the engine 1 is detected by the crank angle sensor 29 described above. In this case, in order to avoid erroneous determination due to disturbance, the update state of the pulse signal is monitored for a predetermined time, and if there is no signal change during the predetermined time, the engine stop is determined.

  Therefore, the stop control of the engine 1 based on the stop request is performed until the rotation speed of the engine 1 gradually decreases and the rotation stops until the fuel supply is stopped after the intake side valve opening is reduced. The period for determining whether the engine 1 is stopped prior to meshing the starter gear with the gear on the engine 1 side, and the period until the self-rotating rotation is achieved by cranking by the starter. Completed as each period passes.

  The determination in step S13 is a determination as to whether or not the determination time is in the middle of the stop preparation period. If a negative determination is made in step S13, the process returns. That is, if a negative determination is made in step S13, stop control for automatically stopping the engine 1 has progressed, fuel supply has already been stopped, and the engine speed has started to decrease accordingly. Become. In this case, in order to proceed with the stop control as it is, the process returns without performing any particular control.

  On the other hand, when a positive determination is made in step S13, it is determined whether or not there is a request to stop the stop control (step S14). This stop control stop request is a request output from the eco-run electronic control device 27 when the stop condition described above is not satisfied before the engine 1 is stopped by the stop control. The operation state is requested to return to the state immediately before the start of the stop control, or the drive state is set according to the drive request amount.

  If there is no stop control stop request and a negative determination is made in step S14, the process returns without performing any particular control in order to continue the stop control. On the other hand, if a positive determination is made in step S14 due to a stop request, the engine stop request is turned OFF (step S15). That is, the control for automatically stopping the engine 1 is stopped.

  Specifically, this time point is during the stop preparation period described above and is a period during which the opening degree of the intake throttle valve 19 and the EGR valve 25 is reduced, so that the opening degree increases to the original opening degree. Be made. Therefore, if the stop control stop request is caused by the brake OFF and the accelerator pedal is returned, the engine 1 is returned to the idling state. If the accelerator pedal is depressed, fuel is injected according to the accelerator opening.

  Therefore, in the above control device according to the present invention, even after the stop condition of the engine 1 by so-called eco-run control is established and the stop control is started, during the preparation period for stopping the engine 1 or the intake air If the start condition of the engine 1 is satisfied during the period when the engine is somewhat secured or the fuel is being supplied (when the stop condition is not satisfied), the stop control of the engine 1 is stopped and the engine 1 is returned to the self-rotating state without stopping. That is, the engine 1 enters the self-rotating state without waiting for the above-described preparation period, the period until the engine 1 stops, and the elapse of the period for determining whether to stop. For this reason, the time from when the engine 1 is started to when the engine 1 actually reaches the self-rotating state is shortened, and the control response to the start request is improved.

  As described above, when the stop condition is not established and there is a start request, and the time point of the start request has passed the preparation period, the stop control is continued as it is, and as a result, the engine 1 is forcibly stopped. It is done. In this state, if the start condition is satisfied or there is a start request, the engine 1 is restarted. An example of the control is shown in the flowchart of FIG.

  The routine shown in FIG. 3 is repeatedly executed in the engine electronic control unit 26 every predetermined short time. First, it is determined whether or not the engine 1 is stopped (step S21). If the determination is negative in step S21 because the engine 1 is rotating, it is not necessary to execute the start control, and the routine is exited. On the other hand, if the determination in step S21 is affirmative because the vehicle is stopped, it is determined whether or not the starting condition is satisfied (step S22). As described above, this start condition is a state in which any requirement in the stop condition of the engine 1 is canceled, such as the release of the braking operation, and is thus established by the cancellation of the stop request, or This is established by outputting a predetermined signal from the eco-run electronic control device 27.

  If the determination in step S22 is negative, there is no need to start the engine 1, and the routine returns without performing any particular control. On the other hand, if the determination in step S22 is affirmative, start control of the engine 1 is executed (step S23). The main content of this is to crank the engine 1 with a starter (not shown). At the same time, the opening of the intake throttle valve 19 and the EGR valve 25 is increased, and fuel injection is resumed. The That is, it is control for rotating the engine 1 independently. Therefore, the start control is continued until the engine 1 rotates independently (until affirmative determination is made in step S24), and when the completion of the start is determined in step S24, the routine is terminated. .

  FIG. 4 shows a time chart when the above stop control and start control are performed. When the stop condition of the engine 1 is satisfied after the vehicle stops, the stop request is turned ON at substantially the same time t1. In addition, a signal for validating stop control (cancellation) of the stop control becomes “valid”. This “valid state” continues for the stop preparation period ta. As described above, the stop preparation period ta is a period required to reduce the opening degree of the intake throttle valve 19 and the EGR valve 25 to the fully closed state in order to smoothly stop the rotation of the engine 1.

  If the stop condition is not satisfied at a predetermined time t2 during the preparation period ta and the stop request is turned OFF, the cancel signal is turned ON at the same time. As a result, the intake throttle valve 19 and the EGR valve 25 that have been closed are controlled in the fully open direction, the opening degree thereof is increased to the original state, and the fuel supply is continued. At time t3 when the preparation period ta elapses, the signal for enabling the stop control (cancellation) is returned to the “invalid state”.

  Assuming that the above stop condition is not satisfied does not involve an increase in the required amount of drive such as depression of the accelerator pedal, the rotational speed of the engine 1 is maintained at the idle rotational speed as shown by a thick solid line in FIG. Therefore, if there is a start request, the engine 1 increases the output from the idling state, so that there is no particular delay with respect to the start request, and the control response is good.

  In contrast, in the conventional control, once the stop condition is established and the stop control is started, the engine 1 is restarted after the stop control is completed. The stop request is maintained until the time t4 when the rotation speed reduction accompanying the stop of the injection and the stop determination period tb elapses. Then, during the start control period tc from the time t4, the start control is executed, and the starter starts the engine 1, increases the intake air, and injects fuel.

  For this reason, as indicated by a thin solid line, the engine speed is temporarily stopped and then is in a low speed state until time t5 when the start control is completed. In other words, even if there is a start request at time t2, the completion of the start is delayed until time t5. Such a delay in start-up causes a so-called swaying feeling, which causes a deterioration in drivability or ride comfort.

  When the stop request is turned OFF after the preparation period ta has elapsed (in the case of the thin solid line in FIG. 4), the stop control is continued until the engine 1 is stopped in the above control. Therefore, as indicated by a thin solid line, the engine speed once becomes zero and then increased to the original speed by the start control.

  By the way, in the control shown in FIG. 1 thru | or FIG. 3 mentioned above, it is assumed that the engine 1 will return to a self-sustaining rotation state by stopping the stop control of the engine 1. FIG. However, depending on the stop control stop timing, such as when the opening degree of the intake throttle valve 19 and the EGR valve 25 is almost fully closed, the engine 1 does not return and the engine stalls. There is no possibility of reaching. The control example described below includes control for coping with engine stall (engine stall) in this way.

  The flowchart shown in FIG. 5 is obtained by changing the determination during rotation of the engine 1 in the flowchart shown in FIG. 1 to an engine stall determination process, and the flowchart shown in FIG. 6 is the flowchart shown in FIG. Is added with a process for instructing that stop control has been canceled. First, referring to FIG. 6, after the engine stop request is turned off in step S15, the stop control stop execution flag is turned on (step S16).

  In the flowchart shown in FIG. 5, the engine stall is determined prior to determining whether the stop condition is satisfied. That is, it is determined whether or not the stop control stop execution flag is ON (step S01). If the determination in step S01 is negative, the stop control has not been stopped immediately before, and the engine 1 is rotating normally. Therefore, the process proceeds to step S1, and the stop condition is satisfied. Establishment is determined.

  On the other hand, if an affirmative determination is made in step S01, the stop control is canceled immediately before, so it is determined whether or not a preset engine determination time has elapsed (step S02). The determination of the engine stall is made based on the number of revolutions of the engine 1 after stopping the stop control. Therefore, the determination takes a predetermined time, and in step S02, the passage of the time is awaited. If a negative determination is made in step S02, the process proceeds to step S2.

  On the other hand, if the engine stall determination time has elapsed and a positive determination is made in step S02, it is determined whether an engine stall has occurred (step S03). If the engine 1 fails to return to the self-sustained rotation even though the engine stop control is stopped, the engine 1 is stopped, so that an affirmative determination is made in step S03. In this case, the stop control stop execution flag is turned OFF (step S04).

  In this case, the engine 1 is controlled so as to operate according to the requested drive amount at that time by turning off the stop request, but the engine 1 is actually stalled. Is executed (step S05). For example, the engine 1 is first started by being rotated by a starter so as to be in an operation state corresponding to the required drive amount. The start control is continued until the engine 1 rotates independently and the completion of the start is determined (affirmative determination is made in step S06). After a positive determination is made in step S06, the process returns. That is, since normal start control is executed, even if the engine 1 cannot be returned to the self-sustained rotation by stopping the stop control, the engine 1 can be brought into the self-sustained rotation state.

  If it is determined negative in step S03 because the engine is not stalled, the original state is generated due to stop control stop, and therefore the stop control stop execution flag is turned OFF. (Step S07), the process proceeds to Step S2.

  By the way, in the control example described above, when a stop control stop request is generated within the preparation period ta, the stop control is stopped at that time, and the engine 1 is continuously rotated to return to the original operation state. It was configured to make it. The preparation period ta is a period from when the stop condition is satisfied or when stop control is started until fuel supply to the engine 1 is stopped. The end of the preparation period ta can be defined and determined by stopping the fuel injection. However, in the present invention, it is not necessary that the end of the generation timing of the start request (stop control stop request) for stopping the stop control exactly coincides with the fuel injection stop start time. Even if it is misaligned, there is no particular problem. Therefore, the control when the start request is made after the stop control is started may be executed as follows instead of the control shown in FIGS. 1 to 3 described above.

  FIG. 7 is a flowchart showing an example of the control, and when there is a request to stop the engine 1 (step S31), control for operating the intake throttle valve 19 and the EGR valve 25 to be fully closed is started (step S31). S32). That is, so-called preparation control is started.

  Next, when there is a stop control stop request for stopping the engine 1 (step S33), an elapsed time from the start of the closing operation of the intake throttle valve 19 and the EGR valve 25 (start of control of step S33) is a predetermined reference. Whether the intake throttle opening is equal to or less than a predetermined reference opening Dst (that is, whether the throttle amount of the intake throttle valve 19 is smaller than Dst), or whether the fuel injection stop signal is OFF (fuel) It is determined whether or not the injection signal is ON (step S34).

  The reference time Tst has a time determined based on the time actually measured as the time required until the intake throttle valve 19 and the EGR valve 25 are fully closed, and does not greatly fall below that time. In other words, it is a time that almost coincides with the actual measurement time. Further, the reference opening degree Dst is a throttle amount substantially corresponding to full closing.

  If the determination in step S34 is affirmative, the engine 1 stop request is turned off, and the engine 1 stop control is stopped (step S35). This is the same control as step S15 shown in FIG. 2 described above. Therefore, the engine 1 in the middle of the stop control is returned to the original operation state without being stopped. That is, the engine 1 is continuously operated.

  On the other hand, when a negative determination is made in step S34, the stop control of the engine 1 is continued as it is, and after the engine 1 is stopped, the restart control is executed (step S36). That is, after the determination of the stop of the engine 1 is established, the starter is driven to mesh the gear with the gear on the engine 1 side, and the engine 1 is rotated by the starter in this state, and the intake throttle valve 19 and the EGR valve 25 And start fuel injection.

  Even when the generation timing of the start request during the stop control is determined as described above, a delay occurs particularly when the start request is made immediately after the stop condition is satisfied, as in the control shown in FIGS. Therefore, the output of the engine 1 can be ensured, and as a result, a sense of incongruity such as a so-called feeling of stickiness can be avoided.

  A time chart when the above control is executed is shown in FIG. 8 together with the conventional example. In FIG. 8, when the stop condition (stop request) of the engine 1 is established at time t11, the intake throttle valve 19 and the EGR valve 25 are controlled to be fully closed based on the stop condition. If the start condition (start request) is established at time t12 in the process, the time t12 is before time t13 when the reference time Tst elapses, or time t14 when the intake throttle opening reaches the reference opening Dst. Since it is before or before the time t15 when the fuel injection signal becomes ON, the stop control is immediately stopped. That is, the intake throttle opening is returned to the original value, or the openings of the intake throttle valve 19 and the EGR valve 25 are increased as shown by the broken line in FIG. As a result, as indicated by a broken line in FIG. 8, the engine speed is maintained at the conventional speed, or is increased according to the drive request amount.

  On the other hand, conventionally, the stop control once started is continued until the engine 1 is stopped. Therefore, as shown by the solid line in FIG. 8, the fuel supply is stopped and the engine speed becomes zero t16. At time t17, when the stop determination of the engine 1 is subsequently established, and thereafter at time t18 when the intake throttle opening is reduced and the openings of the intake throttle valve 19 and the EGR valve 25 are increased to the predetermined opening. Start with the starter. Therefore, even if there is a start request immediately after the stop condition is satisfied, the engine 1 is started after the time t18, so that the start response delay becomes significant, and a so-called harsh feeling is generated. End up.

  Still another example of the present invention will be described. As described above, the internal combustion engine targeted by the present invention requires cranking in order to start. In short, the cranking is a state in which the internal combustion engine rotates without depending on the combustion of the fuel, and therefore the cranking is not limited to rotating the internal combustion engine by a starter which is a kind of motor. A state in which the internal combustion engine is rotated by inertial force can also be called a kind of cranking. Therefore, in the present invention, even after the fuel supply is stopped by the stop control, if there is a start request in a state where the engine 1 is rotating with the inertial force, the stop control is stopped and the engine 1 is stopped. Can be controlled to rotate independently.

  FIG. 9 is a flowchart showing an example of the control, and when there is a request to stop the engine 1 (step S41), control for operating the intake throttle valve 19 and the EGR valve 25 to be fully closed is started (step S41). S42). That is, so-called preparation control is started. Then, when the intake throttle valve 19 and the EGR valve 25 are fully closed, fuel injection is stopped (step S43).

  By stopping the fuel injection, the rotational speed of the engine 1 gradually decreases, and it is read that the rotational speed is being reduced (step S44). If there is a stop control stop request (step S45) in the process, it is determined that the engine speed NE at that time can be returned to the self-sustained rotation by performing intake and fuel injection. It is determined whether or not this is the case (step S46).

  If the determination in step S46 is affirmative, the intake throttle valve 19 is controlled to fully open (step S47). Since the engine speed NE further decreases in the process of the fully opening operation, after step S47, the throttle opening amount that can return the engine 1 to the self-sustaining rotation is equal to or less than the predetermined amount Dne that does not cause smoke. It is determined whether or not the engine speed NE at that time is equal to or higher than the second reference speed NEst2 (<NEst1) that can be returned to the self-sustaining rotation by performing fuel injection (step S48). .

  If the determination in step S48 is affirmative, fuel injection is started (step S49). As a result, in a state where the engine 1 is rotated by inertial force, intake air is secured, fuel is supplied, and the rotation speed is sufficient to rotate independently with fuel combustion. From this, the operating state of the engine 1 returns to a state where it rotates independently.

  Thereafter, the stop request of the engine 1 is turned off, and the stop control of the engine 1 is stopped (step S50). The control in step S50 is the same as the control in steps S15 and S35 described above.

  When the engine speed NE at the time when the start request is generated is lower than the first reference speed NEst1, a negative determination is made in step S46, and the intake throttle valve 19 is fully opened. If the engine speed NE at that time is lower than the second reference speed NEst2, a negative determination is made in step S48, the engine 1 is stopped and the engine 1 is temporarily stopped. Then, it restarts using a starter (step S51). This is the same as the conventional restart control.

  FIG. 10 shows a time chart when the control shown in FIG. 9 is performed. At time t21 when the vehicle is stopped, the stop condition of the engine 1 is established and a stop request is generated, and accordingly, the intake throttle opening (the throttle amount of the intake side flow rate adjustment valve) is increased. Thereafter, the engine is fully closed at time t22, and the engine speed starts to decrease.

  When the engine 1 start condition is satisfied and a start request is generated at time t23 when the engine speed is equal to or higher than the first reference speed NEst1, the intake throttle valve 19 and the EGR valve 25 are controlled in the fully open direction to open the intake throttle. The degree is reduced. The opening degree of the intake throttle valve 19 or the EGR valve 25 is increased to such an extent that the intake throttle opening is reduced below the throttle amount Dne, and the engine speed at the time t24 is not less than the second reference speed NEst2. If so, the fuel injection is resumed, and as a result, the engine 1 returns to the self-rotating state.

  Therefore, since the engine 1 enters the self-rotating state at the time t24 immediately after the time t23 when the start request is generated or at the time t25 when a little time has elapsed thereafter, a delay in response to the start request of the engine 1 is avoided. As a result, even if a situation occurs in which the engine 1 is started immediately after the stop condition of the engine 1 in so-called eco-run control is established, the so-called feeling of stickiness can be avoided.

  On the other hand, in the conventional control, even if the start request is generated at the time t23, the starter starts the engine 1 after the time t26 when the engine 1 is stopped and the determination is satisfied. The start of the engine 1 with respect to the engine is greatly delayed, and a feeling of shakiness occurs.

  Here, the relationship between each of the above specific examples and the present invention will be briefly described. The functional means of step S15 shown in FIGS. 2 and 6, the functional means of step S35 shown in FIG. 7, and the step shown in FIG. The functional means of S47 and S49 correspond to the stop control stop means of the present invention, and the functional means of step S04 shown in FIG. 5 corresponds to the restart means of the present invention.

  The present invention is not limited to the specific examples described above. Therefore, the internal combustion engine that is the subject of the present invention may be a diesel engine other than a so-called direct injection type diesel engine, a gasoline engine, or an internal combustion engine that uses gas as fuel. Inhalation type may be used. Further, an internal combustion engine that does not include an exhaust gas recirculation device can be used. In this case, the intake throttle valve or the throttle valve corresponds to the intake side flow rate adjustment valve of the present invention.

It is a flowchart for demonstrating an example of this invention, Comprising: It is a flowchart for generating the stop request | requirement which stops an engine. It is a flowchart for demonstrating the example of control when a starting request | requirement generate | occur | produces during the stop control based on the stop request | requirement. It is a flowchart for demonstrating an example of the starting control of the engine. It is a figure which shows an example of the time chart at the time of performing control of FIG. 1 thru | or FIG. It is a flowchart for generating the stop request | requirement which added the process which performs the confirmation of the engine stall accompanying stop of stop control. FIG. 3 is a flowchart similar to FIG. 2 to which a flag control process indicating that stop control has been canceled is added. FIG. It is a flowchart for stop control stop determination including the process of determining the period replaced with a stop preparation period. It is a figure which shows an example of the time chart at the time of performing control of FIG. It is a flowchart which shows the example of control which stops stop control after the supply of fuel is stopped. It is a figure which shows an example of the time chart at the time of performing control of FIG. It is a block diagram which shows typically the control system of the internal combustion engine made into object by this invention. It is a schematic diagram which shows an example of a crank angle sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 26 ... Electronic control apparatus for engines, 27 ... Electronic control apparatus for eco-runs.

Claims (8)

Execute predetermined stop control including control for stopping fuel supply to the internal combustion engine when a predetermined stop condition is satisfied, and resume fuel supply to the internal combustion engine when a predetermined start condition is satisfied In a stop / start control device for an internal combustion engine that executes start control including control,
An internal combustion engine characterized by comprising stop control stop means for stopping the stop control when the start condition is satisfied within a predetermined period after the stop condition is satisfied and before the internal combustion engine is stopped. Engine stop / start control device. 2. The internal combustion engine according to claim 1, wherein the predetermined period is a period in which stop preparation control is executed prior to stopping the fuel supply and reducing the rotational speed of the internal combustion engine. Stop / start control device. The stop / start control of the internal combustion engine according to claim 2, wherein the stop control stop means includes return control means for executing return control for returning the internal combustion engine to a predetermined operation state in which the internal combustion engine maintains a self-sustaining rotation. apparatus. 3. The internal combustion engine according to claim 1, further comprising restart means for executing start control for starting the internal combustion engine when the internal combustion engine stops even if the stop control is stopped. Engine stop / start control device. The predetermined period is a period until the opening degree of the intake-side flow rate adjustment valve that is reduced in opening degree before the fuel supply is stopped is reduced to a predetermined opening degree. The stop / start control apparatus for an internal combustion engine according to claim 1. 2. The internal combustion engine according to claim 1, wherein the predetermined period is a period until the rotational speed of the internal combustion engine decreases to a predetermined rotational speed after the fuel supply is stopped. Stop / start control device. The stop control stop means is configured to execute control for restarting fuel supply after increasing the opening degree of the intake side flow rate adjustment valve whose opening degree has been reduced prior to stopping the fuel supply. The stop / start control apparatus for an internal combustion engine according to claim 6, wherein The stop control stopping means supplies fuel when the number of revolutions of the internal combustion engine at the time of increasing the degree of opening of the intake side flow regulating valve to a predetermined degree of opening is equal to or higher than a predetermined number of revolutions. 8. The internal combustion engine stop / start control device according to claim 7, wherein the stop / start control device is configured to restart.

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