JP5141673B2 - Idle stop control device for internal combustion engine - Google Patents

Description

The present invention relates to an internal combustion engine idle stop control device which is applied to a combustion control system of an internal combustion engine including an actuator for combustion control of the internal combustion engine, and which performs a process of automatically stopping and restarting the internal combustion engine.

  Conventionally, for example, as shown in Patent Document 1 below, when a predetermined stop condition is satisfied during operation of the internal combustion engine, a process for automatically stopping the internal combustion engine is performed, and then when the predetermined restart condition is satisfied, the internal combustion engine is restarted. A so-called idle stop control for performing a starting process is known. According to the idle stop control, it is possible to obtain the fuel consumption reduction effect of the internal combustion engine.

JP 2007-263047 A

  By the way, the time (starting time) from when the restart of the internal combustion engine is started by the restarting process until the restart of the internal combustion engine is completed becomes longer due to a difference in the internal combustion engine, May vary. In this case, drivability may be reduced, such as being unable to start the vehicle quickly or giving the driver a sense of incongruity. In particular, the drivability may be significantly reduced under conditions where the automatic stop and restart of the internal combustion engine are frequently repeated.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an idle stop control device for an internal combustion engine that can suitably suppress a decrease in drivability.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

Configuration 1 is applied to a combustion control system for an internal combustion engine having an actuator for combustion control of the internal combustion engine, in the idle stop control apparatus for an internal combustion engine causing the engine and treated to restart automatically stopping the said It is characterized by comprising operating means for operating the actuator so as to feedback control a starting time which is a time from when restart of the internal combustion engine is started until it is completed.

  When the operation amount of the actuator is changed, the combustion state of the internal combustion engine changes and the start time changes. In view of this point, in the above invention, the actuator is operated to feedback control the starting time. As a result, it is possible to suppress the occurrence of a situation in which the start-up time becomes long or varies, and thus it is possible to favorably suppress a decrease in drivability.

Configuration 2 is characterized in that, in Configuration 1 , the operation means operates the actuator to the side where the generated torque of the internal combustion engine increases based on the start time exceeding the target value. .

  When the generated torque of the internal combustion engine increases, the engine speed increases and the start-up time is shortened. In view of this point, in the above-described invention, the start time is feedback-controlled to the target value by operating the actuator on the increasing side based on the start time exceeding the target value. Thereby, it is possible to appropriately suppress the occurrence of a situation in which the starting time becomes long, and more appropriately suppress the decrease in drivability.

Configuration 3 is the configuration 2 , wherein the actuator includes a fuel injection valve that supplies fuel to a combustion chamber of the internal combustion engine, and operating the actuator to the increasing side means restarting the internal combustion engine In the period from the start to the completion, the fuel injection valve is operated to increase the fuel injection amount from the fuel injection valve.

  In the above invention, by increasing the fuel injection amount in the period from when restart of the internal combustion engine is started until it is completed (restart period), it is possible to suitably suppress the occurrence of a situation in which the start time becomes longer. .

According to Configuration 4 , in any one of Configurations 1 to 3 , the operation means operates the actuator so that the generated torque of the internal combustion engine decreases based on the start time being less than the target value. It is characterized by being.

  If the operation amount of the actuator is changed to the side where the generated torque of the internal combustion engine decreases, the increase speed of the engine speed decreases and the start time becomes longer. In view of this point, in the above invention, the actuator is operated to the decreasing side based on the fact that the start time is less than the target value. As a result, it is possible to suppress the occurrence of a situation in which the start time varies, and thus more suitably suppress the decrease in drivability.

The configuration 5 further includes calculation means for calculating an increase speed of the engine rotation speed in a period from the start of the restart to the completion in the configuration 4 , and the operation means defines the calculated increase speed. The actuator is operated on the decreasing side based on the fact that the speed is exceeded.

  In the above-described invention, it is possible to accurately determine whether or not excess fuel is supplied to the combustion chamber of the internal combustion engine by referring to the increasing speed of the engine rotation speed. When it is determined that excessive fuel is supplied, the actuator can be operated to the decreasing side.

Configuration 6 is the configuration 4 or configuration 5 , wherein the actuator includes a fuel injection valve that supplies fuel to a combustion chamber of the internal combustion engine, and operating the actuator to the decreasing side means that the internal combustion engine In the period from when the restart of the engine is started to when it is completed, the fuel injection valve is operated to reduce the fuel injection amount from the fuel injection valve.

  In the above invention, by reducing the fuel injection amount during the restart period of the internal combustion engine, it is possible to suitably suppress a situation in which the start time varies, and to reduce the fuel amount required for restarting the internal combustion engine. Further, by reducing the fuel amount, it is possible to suppress an increase in emissions due to the restart of the internal combustion engine.

The system block diagram concerning one Embodiment. The figure which shows the outline | summary of the starting time FB control process concerning the embodiment. The flowchart which shows the starting time FB control process concerning the embodiment. The time chart which shows the starting time FB control processing (increase correction) concerning the embodiment. The time chart which shows the starting time FB control processing (weight reduction correction) concerning the embodiment.

  Hereinafter, an embodiment in which a control device for an internal combustion engine according to the present invention is applied to an in-vehicle engine system will be described with reference to the drawings.

  FIG. 1 shows a system configuration according to the present embodiment.

  The illustrated engine 10 is a compression ignition internal combustion engine (diesel engine). The intake passage 12 of the engine 10 communicates with the combustion chamber 20 defined by the cylinder block 16 and the piston 18 by opening the intake valve 14. In the combustion chamber 20, the tip of the fuel injection valve 22 is disposed so as to protrude. As a result, fuel can be directly injected and supplied to the combustion chamber 20.

  The fuel injected and supplied to the combustion chamber 20 is self-ignited by the compression of the combustion chamber 20 and is used for combustion. The energy generated by the combustion of the fuel is taken out as rotational energy of the output shaft (crankshaft 24) of the engine 10 via the piston 18. Note that the gas used for combustion is discharged as exhaust into the exhaust passage 28 by opening the exhaust valve 26.

  A starter 30 is connected to the crankshaft 24. The starter 30 is started by turning on a starter switch (not shown), and applies initial rotation (cranking) to the crankshaft 24 to start the engine 10.

  The engine 10 is provided with a crank angle sensor 32 that detects the rotation angle of the crankshaft 24 in the vicinity of the crankshaft 24, a water temperature sensor 34 that detects the temperature of cooling water (cooling water temperature) for cooling the engine 10, and the like. . Output signals from these various sensors, the brake sensor 36 that detects the depression amount of the brake pedal, the vehicle speed sensor 38 that detects the traveling speed of the vehicle, and the like are input to an electronic control unit (hereinafter, ECU 40).

  The ECU 40 is mainly composed of a microcomputer including a known CPU, ROM, RAM, and the like. The ECU 40 executes various control programs stored in the ROM based on the input signals from the respective sensors, thereby controlling the combustion of the engine 10 such as the fuel injection control by the fuel injection valve 22 and the start control by the starter 30. Etc.

  In particular, the ECU 40 performs a process (automatic stop process) for automatically stopping the engine 10 by stopping the fuel injection from the fuel injection valve 22 when a predetermined stop condition is satisfied. When established, cranking is performed by starting the starter 30 and fuel injection from the fuel injection valve 22 is started, thereby performing processing (restart processing) for restarting the engine 10 that has been automatically stopped. So-called idle stop control is performed. Thereby, the fuel consumption reduction effect of the engine 10 can be obtained. Here, in the present embodiment, the stop condition is a condition that a logical product of a condition that the brake operation is performed and a condition that the traveling speed of the vehicle becomes 0 is true. On the other hand, the restart condition is a condition that the brake operation is not performed. Here, whether or not the brake operation is performed may be determined based on the output value of the brake sensor 36. Further, the traveling speed of the vehicle may be calculated based on the output value of the vehicle speed sensor 38.

  Further, the ECU 40 performs the fuel injection control in the period (restart period) from the start of the restart process (instruction of restart of the engine 10) by the establishment of the restart condition until the restart is completed (restart period). This is performed by calculating the initial value of the injection amount at the start based on the coolant temperature during the automatic stop of the engine 10 immediately before the restart of the engine is instructed. Specifically, the engine rotation speed detected each time (predetermined time or every predetermined crank angle) until the restart of the engine 10 is completed after the fuel injection valve 22 is operated so as to be the initial value of the injection amount at the start. The initial value is gradually decreased according to the increase. The cooling water temperature may be calculated based on the output value of the water temperature sensor 34. The engine speed may be calculated based on the output value of the crank angle sensor 32.

  By the way, when the restart of the engine 10 is instructed until the restart of the engine 10 is completed (starting time) becomes long or varies, drivability may be deteriorated. Here, the variation in the starting time is caused by the difference in the engine 10 due to the dimensional tolerance of each part of the engine 10 (for example, the crankshaft 24 and the piston 18), the difference in the viscosity of the engine oil, and the like. This is caused by a difference in force on the side that prevents rotation. For example, when the force on the side that prevents the rotation of the crankshaft 24 is increased, the load acting on the starter 30 is increased, so that the increase speed of the rotation speed of the starter 30 is decreased, and thus the start time is increased. . Further, when the force on the side that prevents the rotation of the crankshaft 24 is increased, the increase speed of the engine rotation speed after the torque is generated by the engine 10 is also decreased, and the starting time is increased. If the starting time of the engine 10 becomes long or varies, the drivability may be lowered, such as the vehicle not being able to start quickly or the driver feeling uncomfortable. In particular, in a situation where the automatic stop and restart of the engine 10 are frequently repeated, the drivability may be significantly reduced.

  Therefore, in this embodiment, in order to set a target value for the start time (target start time Ttgt) and to feedback control the start time to the target start time Ttgt, based on the start time and the target start time Ttgt, By performing the process of increasing or decreasing the injection amount (starting time FB control process), it is possible to suppress a decrease in drivability. Hereinafter, the start time FB control process will be described in detail with reference to FIG.

  FIG. 2 shows an outline of the start time FB control process. In the present embodiment, the time when the engine speed NE is equal to or higher than the predetermined threshold Njudge is the time when the restart of the engine 10 is completed.

  In the present embodiment, when the start time (time t1 to t4) is equal to or longer than the target start time Ttgt (time t1 to t3) as shown by the dotted line in the drawing, the start time is different from the target start time Ttgt. Then, the next start-up injection amount is corrected to increase. This is to suppress the occurrence of a situation in which the start time becomes long. That is, as the generated torque of the engine 10 increases due to the increase in the fuel injection amount, the engine speed NE increases at a higher speed (rotational increase speed ΔNE = ΔN / Δt), and the starting time is shortened. Here, the increase correction of the starting injection amount is specifically performed by multiplying the next starting injection amount by a predetermined coefficient (increase correction coefficient β ≧ 1) corresponding to the deviation. The increase correction coefficient β may be set to a larger value as the absolute value of the deviation is larger, for example.

  On the other hand, when the start time (time t1 to t2) is less than the target start time Ttgt and the rotation increase speed ΔNE is equal to or higher than the specified speed α as shown by the solid line in the figure, the rotation increase speed ΔNE and the specified speed α In accordance with the deviation (speed deviation), the next injection quantity at start is reduced and corrected. This is for suppressing variations in the starting time. That is, in view of the fact that when the fuel injection amount is increased, the rotation increase speed ΔNE increases, the rotation increase speed ΔNE is used as a parameter for accurately grasping the degree of excess of the start injection amount. For this reason, the variation in the starting time is suppressed by the above reduction correction based on the rotational increase speed ΔNE. In the present embodiment, the rotation increase speed ΔNE used for the reduction correction is set to the maximum value of the rotation increase speed ΔNE during the restart period of the engine 10. Here, the reduction correction of the starting injection amount is specifically performed by multiplying the next starting injection amount by a predetermined coefficient (a reduction correction coefficient γ, 0 <γ <1) corresponding to the speed deviation. . For example, the decrease correction coefficient γ may be set to a smaller value as the absolute value of the speed deviation increases. The specified speed α is set to a speed realized by an excessive fuel injection amount when the start time is set to be equal to or less than the target start time Ttgt.

  FIG. 3 shows the procedure of the start time FB control process according to the present embodiment. This process is repeatedly executed, for example, at a predetermined cycle by the ECU 40 while the engine 10 is automatically stopped.

  In this series of processes, first, in step S10, it is determined whether or not an instruction to restart the engine 10 is given. Here, whether or not restart is instructed may be determined based on whether or not the restart condition of the engine 10 is satisfied.

  When it is determined in step S10 that the restart of the engine 10 has been instructed, a process (starting time counting process) for measuring the time after it is determined in step S12 that the restart has been instructed is started. This process is a process for measuring the starting time.

  In the subsequent step S14, the start-up injection amount Q is calculated and restart processing is started. In step S16, a rotation increase speed ΔNE is calculated. The rotation increase speed ΔNE may be calculated as a differential calculation value of the engine rotation speed.

  In a succeeding step S18, it is determined whether or not the engine rotational speed NE is equal to or higher than the predetermined threshold value Njudge. This process is a process for determining whether or not the restart of the engine 10 has been completed.

  If it is determined in step S18 that the restart of the engine 10 has not been completed, the process returns to step S14 and the restart process is continued. On the other hand, when it is determined in step S18 that the restart of the engine 10 has been completed, the process proceeds to step S20, and the start time counting process and the restart process are terminated.

  After completion of the process of step S20, it is determined whether or not the start time measured by the start time counting process in step S22 is equal to or greater than the target start time Ttgt.

  If it is determined in step S22 that the start time is equal to or greater than the target start time Ttgt, the process proceeds to step S24, and an increase correction amount for the next start-time injection amount Q according to the deviation between the start time and the target start time Ttgt. (Increase correction coefficient β) is calculated.

  On the other hand, when a negative determination is made in step S22, the process proceeds to step S26, and it is determined whether or not the maximum value of the rotational increase speed ΔNE during the restart period of the engine 10 is equal to or higher than the specified speed α.

  If an affirmative determination is made in step S26, the process proceeds to step S28, and a reduction correction amount (reduction correction coefficient γ) of the next injection quantity Q at the start according to the speed deviation between the maximum value of the rotational increase speed ΔNE and the specified speed α. ) Is calculated.

  When the processes of steps S24 and S28 are completed, the process proceeds to step S30, and the increase correction coefficient β or the decrease correction coefficient γ is stored in the memory of the ECU 40. Thus, when the engine 10 is restarted next time, the starting injection amount Q calculated in the process of step S14 is multiplied by the increase correction coefficient β or the decrease correction coefficient γ stored in the memory, thereby starting the engine. The hour injection amount Q can be corrected to increase or decrease. Here, in order to increase the fuel injection amount from the fuel injection valve 22, the fuel injection time of the fuel injection valve 22 is lengthened, the injection rate of the fuel injection valve 22 and the pressure of the fuel supplied to the fuel injection valve 22 are increased. You can make it higher.

  If a negative determination is made in steps S10 and S26, or if the process of step S30 is completed, this series of processes is temporarily terminated.

  4 and 5 show an example of the start time FB control process in the present embodiment.

  First, referring to FIG. 4, an increase correction mode of the injection quantity Q at start-up is shown. Specifically, FIG. 4 (a) shows the transition of the engine rotational speed NE, FIG. 4 (b) shows the transition of the rotational increase speed ΔNE, and FIG. 4 (c) shows the transition of the starting injection amount Q. 4 (d) shows the transition of the start instruction signal of the engine 10, and FIG. 4 (e) shows the transition of whether or not the start time counting process is executed. In FIG. 4, the response delay time from when the restart of the engine 10 is instructed to when the engine rotational speed NE actually starts to rise is omitted.

  In the example indicated by the dotted line in the figure, at time t1, it is determined that the restart of the engine 10 is instructed by the start instruction signal being switched from Lo to Hi due to the establishment of the restart condition, and the engine speed NE is determined. Begins to rise. Thereafter, it is determined that the restart of the engine 10 is completed when the engine speed NE becomes equal to or higher than a predetermined threshold Njudge at time t3. Here, since it is determined that the starting time (time t1 to t3) is equal to or longer than the target starting time Ttgt, the next starting injection amount Q is corrected to increase as shown by the solid line in the figure. As a result, the next start time (time t1 to t2) can be made shorter than the target start time Ttgt.

  Next, FIG. 5 is used to show a reduction correction mode of the injection quantity Q at the start. Specifically, FIGS. 5A to 5E correspond to FIGS. 4A to 4E.

  In the example indicated by the dotted line in the figure, the start time (time t1 to t2) is shorter than the target start time Ttgt, and the maximum value of the rotational increase speed ΔNE in the restart period (time t1 to t2) is the specified speed α. It is judged that this is the case. For this reason, as shown by the solid line in the figure, the next start-up injection amount Q is corrected to decrease. This makes it possible to bring the next start time (time t1 to t3) closer to the target start time Ttgt.

  Thus, in this embodiment, by performing the start time FB control process, it is possible to suitably suppress the occurrence of a situation in which the start time becomes long or varies, and the start time can be made as uniform as possible. it can.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) When it is determined that the starting time is equal to or longer than the target starting time Ttgt, the next starting injection amount Q is corrected to be increased according to the deviation between the starting time and the target starting time Ttgt. Thereby, it is possible to suitably suppress the occurrence of a situation in which the starting time becomes long, and accordingly, it is possible to suitably suppress a decrease in drivability.

  (2) When it is determined that the start time is less than the target start time Ttgt and the maximum value of the rotational increase speed ΔNE in the restart period is equal to or greater than the specified speed α, the maximum value of the rotational increase speed ΔNE and the specified speed α The injection quantity Q at the next start-up was corrected to decrease according to the speed deviation. As a result, it is possible to suitably suppress the occurrence of a variation in the start time and to reduce the amount of fuel required for restarting the engine 10, thereby appropriately suppressing the decrease in drivability and improving the fuel consumption reduction effect. Can be made. Further, by reducing the fuel amount, it is possible to suppress an increase in emissions resulting from the restart of the engine 10.

(Other embodiments)
The above embodiment may be modified as follows.

  The method for reducing the start injection quantity Q is not limited to the one exemplified in the above embodiment. For example, when it is determined that the start time is less than the target start time Ttgt, the next start-up injection amount Q may be corrected to decrease regardless of the rotation increase speed ΔNE.

  In the above embodiment, the next start injection amount Q is increased or decreased by multiplying the start injection amount Q by the increase correction coefficient β or the decrease correction coefficient γ. However, the present invention is not limited to this. For example, a predetermined correction amount according to the deviation between the start time and the target start time Ttgt is added to the next start injection amount Q to correct the increase, or the speed deviation between the rotational increase speed ΔNE and the specified speed α The amount of correction may be corrected by subtracting the corresponding predetermined correction amount from the next startup injection amount Q.

  The rotation increase speed ΔNE used for the weight reduction correction is not limited to the maximum value of the rotation increase speed ΔNE during the restart period of the engine 10, for example, a predetermined time (for example, after restart is instructed in the restart period) The rotation increase speed ΔNE at a point in time may be used.

  In the above embodiment, the starting point of the start time is set to the time when the restart of the engine 10 is instructed, but is not limited thereto. For example, it may be a time when the engine 10 actually starts (a time when the engine speed exceeds 0).

  The start time FB control process is not limited to the one exemplified in the above embodiment. For example, each time the engine 10 is restarted, the start time measured by the start time counting process (time measuring means) is associated with the cooling water temperature (for example, the cooling water temperature at the start of the time counting) in a situation where the start time is timed. And a memory (storage means) for storing and reading the start time corresponding to the coolant temperature at the time of the current restart from the memory, and at the time of the current start according to the deviation between the read start time and the target start time Ttgt It is good also as processing which corrects injection quantity Q. As a result, it is possible to avoid a decrease in the correction accuracy of the starting injection amount Q due to the difference in the coolant temperature every time the engine 10 is restarted.

  In the above embodiment, the start time is feedback controlled to the target start time Ttgt, but this is not restrictive. For example, feedback control may be performed so that the start time is equal to or less than the target start time Ttgt. In this case, for example, the processing of steps S26 and S28 of FIG.

  In the above embodiment, there may be further provided means for controlling the rotation stop position of the crankshaft 24 to a predetermined position (target stop position) when the engine 10 is automatically stopped. This is to suppress a decrease in the correction accuracy of the starting injection amount Q by suppressing the variation in the starting time caused by the difference in the rotation stop position of the crankshaft 24. That is, if the rotation stop position is different, the stop position of the piston 18 may be different. In this case, the load acting on the starter 30 at the time of cranking is different due to the difference in the compression work by the piston 18 driven along with the cranking, and the starting time varies. Further, instead of not controlling the rotation stop position, the start time measured by the start time counting process every time the engine 10 is restarted, and the rotation stop position of the crankshaft 24 under the situation where the start time is timed. Are stored in association with each other, the start time corresponding to the rotation stop position at the time of the current restart is read from the memory, and the current start time is determined according to the deviation between the read start time and the target start time Ttgt. It is good also as processing which corrects injection quantity Q. Thereby, it can suppress suitably that starting time varies because the rotation stop position of the crankshaft 24 varies for every restart process.

  The actuator for combustion control of the internal combustion engine operated to feedback control the start time to the target start time Ttgt is not limited to the fuel injection valve 22. For example, if the generated torque of the engine 10 can be increased by promoting the atomization of the injected fuel by increasing the pressure (fuel pressure) of the fuel supplied to the fuel injection valve 22 during the automatic stop of the engine 10, The fuel pressure may be adjustable (for example, an electric fuel pump). In this case, for example, the fuel pressure may be increased according to the deviation between the start time and the target start time Ttgt based on the start time being equal to or greater than the target start time Ttgt. Here, the fuel injection amount may not be changed by shortening the fuel injection time.

  -The internal combustion engine is not limited to a compression ignition type internal combustion engine such as a diesel engine. For example, a spark ignition internal combustion engine such as a gasoline engine may be used. In this case, the fuel injection valve 22 is not limited to the one that protrudes into the combustion chamber 20, and is provided in the intake manifold so as to inject and supply fuel near the intake port of each cylinder of the engine 10, for example. Also good.

  The operation amount for feedback control of the start time to the target start time Ttgt is not limited to the fuel injection amount. For example, when the engine 10 is a spark ignition internal combustion engine, the air-fuel ratio of the mixture of intake air and fuel supplied to the combustion chamber 20 may be used as the operation amount. In this case, for example, based on the start time being equal to or greater than the target start time Ttgt, the fuel injection valve 22 and the intake throttle valve are set so that the air-fuel ratio becomes rich according to the deviation between the start time and the target start time Ttgt. Just operate.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 22 ... Fuel injection valve, 30 ... Starter, 32 ... Crank angle sensor, 40 ... ECU (one Embodiment of the control apparatus of an internal combustion engine).

Claims (5)

In an internal combustion engine idle stop control apparatus that is applied to a combustion control system of an internal combustion engine including an actuator for combustion control of the internal combustion engine and performs a process of automatically stopping and restarting the internal combustion engine,
An operating means for operating the actuator to feedback control a start time which is a time from when restart of the internal combustion engine is started until it is completed ;
A calculating means for calculating a maximum value of an increase speed of the engine rotation speed in a period from the start of the restart to the completion thereof;
With
The operating means is configured to perform the internal combustion engine at the next restart of the internal combustion engine on the condition that the start time is less than the target value and the maximum value of the calculated ascending speed is not less than a specified speed. An idling stop control device for an internal combustion engine , wherein the actuator is operated on the side where the generated torque of the engine decreases . The actuator includes a fuel injection valve that supplies fuel to a combustion chamber of the internal combustion engine,
Operating the actuator to the decreasing side means that the fuel injection valve is operated in order to reduce the fuel injection amount from the fuel injection valve in the period from the start of the restart of the internal combustion engine to the completion thereof. The idle stop control device for an internal combustion engine according to claim 1, wherein: The operation means, based on said starting time exceeds the target value, the internal combustion according to claim 1 or 2, wherein the generation torque of the internal combustion engine is to operate the actuator to the increase side Engine idle stop control device. The actuator includes a fuel injection valve that supplies fuel to a combustion chamber of the internal combustion engine,
Operating the actuator to the increasing side means that the fuel injection valve is operated in order to increase the fuel injection amount from the fuel injection valve in the period from the start of restart of the internal combustion engine to the completion thereof. 4. The idle stop control device for an internal combustion engine according to claim 3, wherein The control means for controlling the rotation stop position of the output shaft of the internal combustion engine to a predetermined target stop position at the time of the automatic stop of the internal combustion engine is further provided. Idling stop control device for internal combustion engine.

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