JP4802860B2 - Internal combustion engine stop position control system - Google Patents

Description

  The present invention relates to a technique for stopping a crankshaft at a desired position when the operation of an internal combustion engine is stopped.

  In recent years, in order to improve the restartability of an internal combustion engine mounted on a vehicle or the like, development of a technique for stopping the crankshaft in a desired target crank angle range has been advanced. As this kind of technology, after stopping the operation of auxiliary machinery and retarding the ignition timing, the engine speed is reduced by adjusting the throttle opening, and the engine speed is reduced to a predetermined speed range. A technique for stopping fuel injection at a point in time is known (see, for example, Patent Document 1).

In addition, a technique for stopping fuel injection after adjusting the rotational speed of an internal combustion engine to a desired rotational speed by a motor generator has been proposed (see, for example, Patent Document 2).
JP 2004-293444 A JP 2004-263666 A

  An object of the present invention is to provide a motor generator and the like in a stop position control system for an internal combustion engine that stops combustion of the internal combustion engine when the engine speed is in a predetermined speed range in order to stop the crankshaft within a target crank angle range. The present invention provides a technique capable of optimizing the stop position of the crankshaft without relying on the external power of the engine.

The present invention employs the following means in order to solve the above-described problems. That is, the present invention relates to a stop position control system for an internal combustion engine that stops the crankshaft in a target crank angle range by stopping combustion of the internal combustion engine when the engine speed is in a predetermined speed range. Holding means for holding the throttle opening at a predetermined opening when the stop condition is satisfied, and the engine speed is first retarded by a predetermined amount or more when the operation stop condition of the internal combustion engine is satisfied. It is lower than the rotational speed range, followed by the engine speed to execute a rotational speed control for advancing the ignition timing in order to converge the engine rotational speed when the below said predetermined speed range to said predetermined speed range control means And so on.

  The stop position of the crankshaft works to maintain the crankshaft rotational resistance (force against the crankshaft rotation) and the inertial energy of the crankshaft when the combustion of the internal combustion engine stops (crankshaft rotation state). It depends on the size of the energy.

  The rotational resistance described above includes internal friction resistance of internal combustion engine, compression reaction force, intake / exhaust resistance, driving loss of auxiliary equipment (such as an alternator and an air conditioner compressor), and the like.

  The magnitude of the inertia energy correlates with the engine speed at the time of combustion stop (hereinafter referred to as “combustion stop speed”). For this reason, when the magnitude of the rotational resistance is stable, the stop position of the crankshaft is correlated with the combustion stop rotational speed.

Therefore, the combustion stop rotational speed range (predetermined rotational speed range) in which the stop position of the crankshaft falls within the target crank angle range can be experimentally obtained in advance. As a result, the crankshaft can be stopped in the target crank angle range by stopping the combustion of the internal combustion engine when the engine speed has converged to the predetermined speed range.

  Examples of a method for converging the engine speed to the predetermined speed range include a method for increasing or decreasing the intake air amount of the internal combustion engine by adjusting the opening of the throttle valve. However, there is a response delay due to a delay in transport of intake air from when the opening of the throttle valve (hereinafter simply referred to as “throttle opening”) is changed until the intake air amount of the internal combustion engine changes. For this reason, there is a possibility that the required time from when the operation stop condition is satisfied to when the operation is actually stopped becomes longer.

  Further, when the throttle opening changes, the intake pipe negative pressure changes accordingly. When the intake pipe negative pressure changes, the magnitude of the rotational resistance also changes. Therefore, even if the combustion stop rotational speed is within the predetermined rotational speed range, the stop position of the crankshaft may be far from the target crank angle range.

  On the other hand, the control means of the present invention controls the engine speed (rotational speed control) by adjusting the ignition timing when the combustion stop rotational speed is converged to a predetermined rotational speed range. Since the change in the ignition timing is immediately reflected in the engine speed, the time required for the engine speed to converge to the predetermined speed range can be shortened. Further, if the throttle opening at that time is fixed at a constant opening, the rotational resistance becomes substantially constant. Therefore, if the combustion is cut when the engine speed converges to a predetermined speed range, the crankshaft It becomes easy to stop in the target crank angle range.

  If the ignition timing is retarded in the above-described rotation speed control, the internal combustion engine is likely to misfire. In particular, if the throttle opening at that time is relatively small, misfire of the internal combustion engine is more likely to occur due to a synergistic effect with the retard of the ignition timing.

  Accordingly, the stop position control system for an internal combustion engine according to the present invention holds the throttle opening at a relatively large predetermined opening by the holding means when the rotational speed control is performed by the control means.

  As such a predetermined opening, an opening larger than the throttle opening when the internal combustion engine is idling can be exemplified.

  In this case, the combustion stop rotational speed can be converged to a predetermined rotational speed range without inducing a misfire of the internal combustion engine. As a result, the stop position of the crankshaft can be optimized without depending on external power such as a motor generator.

Further, in the stop position control system for an internal combustion engine according to the present invention, the control means, before executing the rotational speed control, a predetermined amount or more retarded point fire timing so that the engine speed is lower than a predetermined rotational speed range Ru is.

  In this case, since the engine speed rapidly decreases, the time required for the engine speed to converge to the predetermined number of times can be shortened. As a result, the time required from when the operation stop condition is satisfied to when the operation is actually stopped is shortened.

  In the stop position control system for an internal combustion engine according to the present invention, the control means may maintain a state where the ignition timing is retarded by a predetermined amount or more for a predetermined time. This is based on the knowledge that when the state where the ignition timing is retarded by a predetermined amount is continued for a certain period of time, the engine speed is stabilized in a state lower than the predetermined speed range.

  In the stop position control system for an internal combustion engine according to the present invention, the control means acquires a maximum value of the engine speed in the expansion stroke of the cylinder, and the engine speed so that the acquired maximum value converges in the predetermined speed range. Control may be performed.

  The maximum value of the engine speed in the expansion stroke of the cylinder corresponds to the engine speed when the combustion pressure of the cylinder reaches a peak. For this reason, if the rotational speed control is performed so that the maximum value converges in a predetermined rotational speed range, the crankshaft is likely to stop within the target crank angle range.

  By the way, when the rotational speed control is performed so that the local maximum value converges in the predetermined rotational speed range, it is preferable to immediately stop the combustion of the internal combustion engine when the local maximum value converges in the predetermined rotational speed range. However, if the timing at which the engine speed reaches the maximum value is delayed due to the retard of the ignition timing, there is a possibility that the ignition and / or fuel injection of the subsequent cylinder cannot be stopped.

  Therefore, the control means may limit the adjustment range of the ignition timing in the rotation speed control within a predetermined range. In this case, since the timing at which the engine speed reaches the maximum value is not excessively delayed, it becomes possible to immediately stop the combustion of the internal combustion engine when the maximum value has converged to the predetermined speed range.

  If the ignition timing is limited to a predetermined range, it may be assumed that the engine speed does not converge to the predetermined speed range. In such a case, the holding means may correct the throttle opening (predetermined opening). If the rotational speed control is performed again after the throttle opening is corrected, the engine rotational speed can be reliably converged to a predetermined rotational speed range.

  In the stop position control system for an internal combustion engine according to the present invention, the control means is configured to perform the internal combustion engine control when the rotation time control execution time or the elapsed time from when the operation stop condition of the internal combustion engine is satisfied exceeds a predetermined time. The operation of the engine may be stopped immediately.

  Excessive time from when the internal combustion engine stop request is generated until the engine speed converges to the predetermined speed range may give the driver a sense of incongruity, but there is a limit on the execution time of the speed control. The occurrence of the above-described problems can be avoided.

  An internal combustion engine stop position control system according to the present invention estimates an amount of crankshaft rotational resistance, and corrects the predetermined rotational speed range based on the rotational resistance estimated by the estimation unit. And a correction unit.

  The magnitude of the rotational resistance of the crankshaft varies depending on dimensional tolerances and assembly tolerances of components constituting the internal combustion engine, and may vary depending on changes over time of the internal combustion engine. When the magnitude of the rotational resistance of the crankshaft changes, the predetermined rotational speed range suitable for stopping the crankshaft at a desired position also changes.

  On the other hand, when the predetermined rotational speed range is corrected according to the magnitude of the rotational resistance of the crankshaft, even if the magnitude of the rotational resistance changes due to individual differences or changes over time of the internal combustion engine, Can be stopped within the target crank angle range.

  At that time, the estimation means estimates the magnitude of the rotational resistance based on the engine speed in a predetermined crank angle range after the combustion of the internal combustion engine is stopped (fuel injection stop and / or ignition stop). Also good.

After the combustion of the internal combustion engine is stopped, fuel is not combusted in the cylinder, so that the engine speed is reduced only by the influence of the rotational resistance. For this reason, the engine speed in the predetermined crank angle range (hereinafter referred to as “the engine speed after combustion stop”) decreases as the rotational resistance increases, and increases as the rotational resistance decreases. Therefore, it can be estimated that the rotational resistance of the crankshaft increases as the engine speed after the combustion stops decreases and decreases as the engine speed after the combustion stops increases.

  According to the present invention, in a stop position control system for an internal combustion engine that stops combustion of the internal combustion engine when the engine speed is in a predetermined speed range, the stop position of the crankshaft is not dependent on external power such as a motor generator. Can be optimized.

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

<Example 1>
First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied.

  An internal combustion engine 1 shown in FIG. 1 is a 4-stroke cycle spark ignition internal combustion engine (gasoline engine) having a plurality of cylinders 2. An intake passage 3 and an exhaust passage 4 communicate with the cylinder 2 of the internal combustion engine 1.

  A fuel injection valve 5 that injects fuel into the cylinder 2 is provided in the intake passage 3. Further, the intake passage 3 is provided with a throttle valve 6 that controls the amount of air flowing through the intake passage 3 and an air flow meter 7 that outputs an electrical signal corresponding to the amount of air flowing through the intake passage 3. It has been.

  Further, the internal combustion engine 1 is provided with an intake valve 8 that opens and closes an open end of the intake passage 3 facing the cylinder 2 and an exhaust valve 9 that opens and closes an open end of the exhaust passage 4 facing the cylinder 2. The intake valve 8 and the exhaust valve 9 are driven to open and close by an intake camshaft 10 and an exhaust camshaft 11, respectively.

  A spark plug 12 for igniting the air-fuel mixture flowing into the cylinder 2 is disposed at the upper part of the cylinder 2. A piston 13 is slidably provided in the cylinder 2. The piston 13 is connected to the crankshaft 15 via a connecting rod 14. A crank position sensor 16 that detects a rotation angle of the crankshaft 15 is disposed in the internal combustion engine 1 in the vicinity of the crankshaft 15.

  The internal combustion engine 1 configured as described above is provided with an ECU 17. The ECU 17 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like. The ECU 17 is input with measured values of various sensors such as the air flow meter 7 and the crank position sensor 16 described above.

  The ECU 17 controls the fuel injection valve 5 and the spark plug 12 based on the measurement values of the various sensors described above. For example, the ECU 17 performs stop position control for stopping the crankshaft 15 in a desired target crank angle range when the operation stop condition of the internal combustion engine 1 is satisfied.

  Hereinafter, stop position control in the present embodiment will be described.

  The stop position of the crankshaft 15 is determined according to the magnitude of the rotational resistance acting on the crankshaft 15 and the magnitude of the inertia energy that the crankshaft 15 has when the combustion of the internal combustion engine 1 is stopped.

  The magnitude of the inertia energy correlates with the combustion stop rotational speed. Therefore, if the magnitude of the rotational resistance is constant, the stop position of the crankshaft 15 correlates with the combustion stop rotational speed as shown in FIG.

  Therefore, when the combustion of the internal combustion engine 1 is stopped when the engine speed is in a specific range (for example, A1 and A2 in FIG. 2), the crankshaft 15 has a substantially constant crank angle range (for example, in FIG. 2). Stop at B).

  There may be a plurality of combustion stop rotational speed ranges corresponding to the target crank angle range. In such a case, the lowest combustion stop rotational speed range (in the example of FIG. 2) as long as the internal combustion engine 1 can operate independently. Then, it is preferable that A1) is selected. This is because the accuracy of the stop position of the crankshaft 15 increases as the combustion stop rotational speed decreases.

  As a method of converging the engine speed to a desired combustion stop speed range (hereinafter referred to as “target combustion stop speed range”), the intake air amount of the internal combustion engine 1 is increased or decreased by adjusting the opening of the throttle valve 6. Although there is a method, it is not preferable because the stop position control execution time (the time required until the rotation of the crankshaft 15 is stopped after the operation stop condition is satisfied) may be prolonged or the rotation resistance may be changed. .

  Therefore, in the stop position control of the present embodiment, the ECU 17 adjusts the ignition timing while fixing the opening degree of the throttle valve 6 to a constant opening degree so as to converge the engine speed to the target combustion stop speed range. Control was done.

  FIG. 3 is a timing chart showing the execution procedure of the rotational speed control of this embodiment. When the operation stop condition of the internal combustion engine 1 is satisfied (t1 in FIG. 3), the ECU 17 sets the auxiliary machine (the alternator, the compressor of the air conditioner, or the power to make the rotation resistance of the crankshaft 15 constant). The operation of the steering hydraulic pump or the like is stopped, and the opening of the throttle valve 6 is fixed at a constant opening α.

  When the operation of the auxiliary machine is stopped, the load on the internal combustion engine 1 is reduced, and the engine speed increases. At this time, if the opening degree of the throttle valve 6 is fixed at a constant opening degree α, the idle speed control (ISC) does not work, so the engine speed remains increased.

  Therefore, in order to quickly reduce the engine speed to the target combustion stop speed range, it is necessary to rapidly decrease the engine speed by adjusting the ignition timing. Therefore, the ECU 17 significantly retards the ignition timing before starting the execution of the rotational speed control.

  Specifically, the ECU 17 sets the ignition timing simultaneously with stopping the operation of the auxiliary machine and fixing the opening of the throttle valve 6 when the operation stop condition of the internal combustion engine 1 is satisfied (t1 in FIG. 3). Quantitative Δ Ti retarded.

  The predetermined amount ΔTi is a fixed value determined so that the engine speed is lower than the target combustion stop rotational speed range A, and is obtained experimentally in advance.

  Further, since the internal combustion engine 1 is likely to misfire if the ignition timing is significantly retarded, the above-described constant opening α may be set larger than the throttle opening when the internal combustion engine 1 is in the idling operation state. preferable.

When the ignition timing is retarded by a predetermined amount ΔTi by the above-described procedure, the engine speed is rapidly reduced while the misfire of the internal combustion engine 1 is suppressed. When the engine rotational speed falls below the target combustion stop rotational speed range A (t2 in FIG. 3), the ECU 17 starts the rotational speed control so as to converge the engine rotational speed to the target combustion stop rotational speed range. Specifically, when the ECU 17 detects that the engine rotational speed has fallen below the target combustion stop rotational speed range A, the ECU 17 gradually advances the ignition timing of the cylinder 2 where ignition is performed thereafter.

  When the engine speed enters the target combustion stop rotational speed range by the rotational speed control (t3 in FIG. 3), the ECU 17 fixes the ignition timing. However, the combustion stability of the internal combustion engine 1 increases as the ignition timing approaches the normal ignition timing Tib. Therefore, even after the engine speed enters the target combustion stop speed range, the engine speed remains within the target combustion stop speed range. The advance of the ignition timing may be continued within a range that does not deviate.

  By the way, a method of immediately stopping the combustion of the internal combustion engine 1 when the engine speed enters the target combustion stop speed range (t3 in FIG. 3) is also conceivable. However, when the engine speed enters the target combustion stop rotational speed range from the middle to the second half of the expansion stroke of a certain cylinder 2, the fuel injection and ignition of the next cylinder 2 cannot be stopped. For this reason, there may be a time lag from the time when it is determined that the engine speed has converged to the target combustion stop speed range until the combustion of the internal combustion engine 1 is actually stopped.

  At this time, if the engine speed is in a transient state as shown in FIGS. 4 and 5, the engine speed when combustion of the internal combustion engine 1 is actually stopped deviates from the target combustion stop speed range, There is a possibility that the stop position of the shaft 15 is greatly separated from the target crank angle range.

  On the other hand, when the engine speed has converged to the target combustion stop speed range without interruption (hereinafter referred to as “stabilization time”) becomes equal to or longer than a predetermined time Δt (in FIG. 3). At t4), the combustion of the internal combustion engine 1 is stopped. When the combustion of the internal combustion engine 1 is stopped by this method, the engine speed when the combustion of the internal combustion engine 1 is actually stopped does not deviate greatly from the target combustion stop rotational speed range. It becomes easy to stop in the target crank angle range.

  Next, the flow of stop position control in this embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing a stop position control routine in the present embodiment. The stop position control routine is a routine stored in advance in the ROM of the ECU 17 and is repeatedly executed by the ECU 17 at predetermined intervals.

  In the stop position control routine of FIG. 6, the ECU 17 first determines in S101 whether or not an operation stop condition for the internal combustion engine 1 is satisfied. Examples of the operation stop condition of the internal combustion engine 1 include a manual stop condition (manual operation of turning off the ignition switch) and establishment of an idle stop condition.

  If a negative determination is made in S101, the ECU 17 resets the counter value C to “0” in S116, and temporarily ends the execution of this routine. The counter counts the time during which the engine speed Ne continuously converges to the target combustion stop speed range A.

  If an affirmative determination is made in S101, the ECU 17 proceeds to S102. In S102, the ECU 17 determines whether or not “1” is set in the rotation speed control flag. The rotation speed control flag is a storage area set in advance in the RAM or backup RAM of the ECU 17, and is set to “1” when the execution of the rotation speed control is started and reset to “0” when the execution of the rotation speed control is completed. Is done.

If a negative determination is made in S102 (rotational speed control flag = 0), the ECU 17 regards that rotational speed control has not yet started, and proceeds to S103. In S103, the ECU 17 stops the operation of the auxiliary machine. Subsequently, the ECU 17 fixes the opening of the throttle valve 6 to a constant opening α in S104, and retards the ignition timing Ti of the spark plug 12 by a predetermined amount ΔTi in S105.

  The processing order of S103 to S105 described above is not limited to the example of FIG. 6, but since the responsiveness of the ignition timing is higher than the responsiveness of the throttle valve 6, the process of S105 is the process of S104. It is preferred to be performed later.

  In S106, the ECU 17 determines whether or not the engine speed Ne is lower than a lower limit value Nemin of the target combustion stop speed range A. If a negative determination is made in S106, the ECU 17 once ends the execution of this routine after executing the process of S116.

  If an affirmative determination is made in S106, the ECU 17 proceeds to S107 and sets "1" to the above-described rotation speed control flag.

  In S108, the ECU 17 starts executing the rotation speed control. That is, the ECU 17 advances the ignition timing Ti by a small amount in S108. When the ECU 17 finishes executing the process of S108, the ECU 17 once ends the execution of this routine after executing the process of S116.

  Thereafter, when a certain period of time elapses, the ECU 17 executes this routine again. In that case, the ECU 17 makes a positive determination in S102. If an affirmative determination is made in S102, the ECU 17 proceeds to S109.

  In S109, the ECU 17 determines whether or not the engine speed Ne is within the target combustion stop speed range A, in other words, the engine speed Ne is equal to or higher than the lower limit value Nemin of the target combustion stop speed range A and the target combustion stop speed. It is determined whether or not the upper limit value Nemax of the numerical range A is not more than.

  If a negative determination is made in S109, the ECU 17 proceeds to S110, and determines whether or not the engine speed Ne is higher than the upper limit value Nemax. If a negative determination is made in S110, the engine speed Ne is lower than the lower limit value Nemin. Therefore, the ECU 17 once ends the execution of this routine after executing the processes of S108 and S116 described above.

  If an affirmative determination is made in S110 (Ne> Nemax), the engine speed Ne has increased too much, so the ECU 17 proceeds to S116 after retarding the ignition timing Ti by a small amount in S111.

  When such speed control is repeatedly executed, the engine speed Ne converges to the target combustion stop speed range A. As a result, the ECU 17 makes a positive determination in S109.

  If an affirmative determination is made in S109, the ECU 17 proceeds to S112 and increments the value C of the counter by one.

  In S113, the ECU 17 determines whether or not the counter value C has reached a predetermined value Cb or more. The predetermined value Cb is a value determined based on the predetermined time Δt in FIG.

If a negative determination is made in S113 (C <Cb), the ECU 17 once terminates execution of this routine. On the other hand, when an affirmative determination is made in S113 (C ≧ Cb), the ECU 17 proceeds to S114.

  In S114, the ECU 17 stops the operation of the fuel injection valve 5 and the spark plug 12 to stop the combustion of the internal combustion engine 1.

  Subsequently, the ECU 17 resets the rotation speed control flag and the counter value C to “0” in S115 and S116, respectively, and ends the execution of this routine.

  As described above, when the ECU 17 executes the stop position control routine, the control means and the holding means according to the present invention are realized.

  Therefore, in the stop position control of the present embodiment, the engine speed is converged to the target combustion stop speed range A by adjusting the ignition timing while fixing the throttle opening to a constant opening α. For this reason, compared with the case where the engine speed is converged to the target combustion stop speed range A by adjusting the throttle opening, stop position control with high responsiveness and high accuracy can be realized.

  Further, since the stop position control of the present embodiment greatly reduces the ignition timing before the execution of the rotational speed control, the time required until the engine rotational speed converges to the target combustion stop rotational speed range A can be shortened. Is possible.

  Further, the stop position control of the present embodiment stops the combustion of the internal combustion engine 1 when the engine speed is stable in the target combustion stop speed range A. Therefore, the actual combustion stop speed is set to the target combustion stop speed. It is possible to prevent a large deviation from the numerical range A.

  Therefore, according to the stop position control of the present embodiment, it is possible to optimize the stop position of the crankshaft without depending on external power such as a motor generator.

<Example 2>
Next, a second embodiment of the present invention will be described with reference to FIGS. Here, a configuration different from that of the first embodiment will be described, and description of the same configuration will be omitted.

  In the stop position control of the first embodiment described above, the engine speed Ne is decreased from the target combustion stop speed range A by retarding the ignition timing Ti by a predetermined amount ΔTi before the start of execution of the speed control. However, the amount of decrease ΔNe of the engine speed Ne required at that time varies depending on the intake air amount when the operation stop condition is satisfied (hereinafter referred to as “reference intake air amount”).

  For this reason, when the predetermined amount ΔTi is set to a fixed value, it is necessary to set the predetermined amount ΔTi to a relatively large value. When the predetermined amount ΔTi is fixed to a relatively large value, the engine speed Ne may be lower than necessary with respect to the target combustion stop rotational speed region A when the reference intake air amount is relatively small. .

  Therefore, in the stop position control of this embodiment, the predetermined value ΔTi is changed according to the reference intake air amount. At this time, since the decrease amount ΔNe increases as the reference intake air amount increases, the predetermined amount ΔTi is determined to increase as the reference intake air amount increases as shown in FIG.

Thus, when the predetermined amount ΔTi is changed according to the reference intake air amount, the engine speed Ne is prevented from being excessively lower than the target combustion stop speed range A. In other words, when the ignition timing Ti is the predetermined amount ΔTi, the engine speed Ne is not greatly separated from the target combustion stop speed range A. As a result, in the subsequent rotational speed control, the engine rotational speed Ne quickly converges to the target combustion stop rotational speed range A, so that the execution time of the rotational speed control can be shortened.

  Hereinafter, the flow of the stop position control in the present embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing a stop position control routine in the present embodiment. In the stop position control routine of FIG. 8, the same processes as those of the stop position control routine (see FIG. 6) of the first embodiment are denoted by the same reference numerals.

  In the stop position control routine of FIG. 8, if the ECU 17 makes an affirmative determination in S <b> 101, the ECU 17 proceeds to S <b> 201 and acquires the reference intake air amount Ga <b> 0 via the air flow meter 7.

  In S202, the ECU 17 calculates a predetermined amount ΔTi based on the reference intake air amount Ga0 acquired in S201 and the relationship shown in FIG.

  When the ECU 17 finishes executing the process of S202, the ECU 17 proceeds to S102. The processing of S102 to S105 is the same as the stop position control routine (see FIG. 6) of the first embodiment described above.

  When the ECU 17 finishes executing the process of S105, the ECU 17 proceeds to S203 and activates the timer T. This timer T is a timer that measures the elapsed time from the time when the ignition timing Ti is retarded by a predetermined amount ΔTi.

  In S204, the ECU 17 determines whether or not the measurement time of the timer T has reached a certain time Tb or more. The fixed time Tb corresponds to the time required for the engine speed Ne to become lower than the target combustion stop speed range A, and is obtained experimentally in advance.

  If an affirmative determination is made in S204, the ECU 17 regards the engine speed Ne as being lower than the target combustion stop speed range A, and executes the processes of S107 and S108.

  Subsequently, the ECU 17 stops the operation of the timer T in S205 and resets the measurement time of the timer T to “0”.

  As described above, when the ECU 17 executes the stop position control routine of FIG. 8, the predetermined amount ΔTi is determined according to the reference intake air amount, so that the engine rotation occurs when the ignition timing Ti is retarded by the predetermined amount ΔTi. The number Ne is not greatly separated from the target combustion stop rotation speed range A. As a result, the time required for the subsequent rotation speed control can be shortened.

<Example 3>
Next, a third embodiment of the present invention will be described. Here, configurations different from those of the first and second embodiments described above will be described, and description of similar configurations will be omitted.

  In the first and second embodiments described above, the stop position control is executed until the engine speed Ne converges to the target combustion stop speed range A. However, the execution time of the stop position control is excessively long. Then, there is a possibility that the driver of the vehicle is uncomfortable or the effect of the idle stop control cannot be obtained sufficiently.

  Therefore, in the stop position control of the present embodiment, the ECU 17 measures the elapsed time from the time when the operation stop condition of the internal combustion engine 1 is satisfied or the elapsed time from the start of execution of the rotational speed control, and the elapsed time is a fixed time. When the value exceeds the value, the combustion of the internal combustion engine 1 is immediately stopped.

  In this case, since the execution time of the stop position control is not excessively prolonged, it is possible to prevent the vehicle driver from feeling uncomfortable or preventing a contradiction such as insufficient effect of the idle stop control. it can.

<Example 4>
Next, a fourth embodiment of the present invention will be described with reference to FIGS. Here, a configuration different from that of the first embodiment will be described, and description of the same configuration will be omitted.

  In the present embodiment, an example will be described in which a restriction is provided in the adjustment range of the ignition timing Ti in the rotational speed control. The rotational speed control is preferably performed such that the maximum value of the engine rotational speed in the expansion stroke of each cylinder 2 converges to the target combustion stop rotational speed range A.

  Since the above-mentioned maximum value corresponds to the engine speed when the combustion pressure of each cylinder 2 reaches the peak, combustion of the internal combustion engine 1 stops when the maximum value converges to the target combustion stop speed range A. Then, it becomes easy to stop the crankshaft 15 in the target crank angle range.

  By the way, the timing at which the engine speed reaches the maximum value in the expansion stroke of each cylinder 2 (hereinafter referred to as “peak timing”) varies according to the ignition timing Ti. For example, as shown in FIG. 9, the peak timing tends to be delayed as the ignition timing Ti is delayed.

  However, if the peak timing is excessively delayed due to the retard of the ignition timing Ti, the ignition and / or fuel injection of the subsequent cylinder 2 may not be stopped when the maximum value of the engine speed is detected.

  Further, when the ignition timing Ti is advanced, the peak timing is advanced, but the ignition timing Ti of the subsequent cylinder 2 is advanced, so that the subsequent cylinder 2 is detected when the maximum value of the engine speed is detected. It may be difficult to stop the ignition.

  Therefore, in the rotational speed control of the present embodiment, the ECU 17 can limit the adjustment range of the ignition timing Ti in the rotational speed control to a predetermined range so that the combustion of the subsequent cylinder 2 can be stopped at the peak timing. did.

  If the adjustment range of the ignition timing Ti is limited in this way, the combustion of the internal combustion engine 1 can be stopped immediately when the maximum value of the engine speed converges to the target combustion stop speed range A. It is possible to shorten the execution time of the rotational speed control.

  Hereinafter, the flow of the stop position control of the present embodiment will be described with reference to FIG. FIG. 10 is a flowchart showing a stop position control routine in the present embodiment. In the stop position control routine of FIG. 10, the same processes as those of the stop position control routine (see FIG. 6) of the first embodiment described above are denoted by the same reference numerals.

  In the stop position control routine of FIG. 10, in S301, the ECU 17 determines whether or not the ignition timing Ti advanced in S108 is earlier than the advance side guard value Tiad.

  If an affirmative determination is made in S301, the ECU 17 proceeds to S302 and sets the advance side guard value Tiad as the ignition timing Ti. On the other hand, if a negative determination is made in S301, the ECU 17 skips S302 and operates the spark plug 12 according to the ignition timing Ti set in S108.

In S303, the ECU 17 determines whether or not the ignition timing Ti retarded in S111 is later than the retard-side guard value Tire.

  If an affirmative determination is made in S303, the ECU 17 proceeds to S304, and sets the retard-side guard value Tire as the ignition timing Ti. On the other hand, if a negative determination is made in S303, the ECU 17 skips S304 and operates the spark plug 12 according to the ignition timing Ti set in S111.

  As described above, when the ignition timing adjustment range in the rotational speed control is limited, it is determined that the maximum value of the engine rotational speed has converged to the target combustion stop rotational speed range A (for example, FIG. 10). When an affirmative determination is made in S113, the combustion of the internal combustion engine 1 can be stopped immediately. As a result, the execution time of the rotational speed control can be shortened.

  It should be noted that if the ignition timing adjustment range is limited, the maximum value of the engine speed may not converge to the target combustion stop speed range A. In such a case, the ECU 17 may perform the rotational speed control again after correcting the opening of the throttle valve 6 (constant opening α).

  In this case, although there is a possibility that the execution time of the stop position control becomes long, the crankshaft 15 can be stopped in the target crank angle range almost certainly.

<Example 5>
Next, a fifth embodiment of the present invention will be described with reference to FIGS. Here, a configuration different from that of the first embodiment will be described, and description of the same configuration will be omitted.

  The magnitude of the rotational resistance acting on the crankshaft 15 varies depending on dimensional tolerances and assembly tolerances of parts constituting the internal combustion engine 1 and may vary depending on changes over time of the internal combustion engine 1. When the magnitude of the rotational resistance acting on the crankshaft 15 changes, the target combustion stop rotational speed range A also changes.

  Therefore, in this embodiment, the ECU 17 corrects the target combustion stop rotational speed region A based on a physical quantity that correlates with the magnitude of the rotational resistance acting on the crankshaft 15.

  Specifically, the ECU 17 has a predetermined crank angle range after the combustion of the internal combustion engine 1 is stopped (for example, 30 to 60 ° CA after the expansion stroke top dead center of the cylinder 2 that reaches the expansion stroke first after the combustion is stopped). The magnitude of the rotational resistance is estimated based on the engine speed at (the engine speed after combustion is stopped).

  After the combustion of the internal combustion engine 1 is stopped, fuel is not burned in the cylinder 2, so that the engine speed is reduced only by the influence of the rotational resistance. Therefore, it can be considered that the rotational resistance increases as the engine speed after combustion stops decreases, and decreases as the engine speed increases after combustion stops.

  However, the engine speed after the combustion is stopped varies depending on factors other than the magnitude of the rotational resistance. For example, the engine speed after the combustion is stopped varies depending on factors such as variations in ignition energy, variations in the combustion state of the air-fuel mixture, or changes in ignition timing due to rotation speed control.

  Therefore, a range (hereinafter referred to as “allowable engine speed region”) B that can be taken by the engine speed after the combustion is stopped due to the above-described factors is obtained in advance, and the change in the engine speed after the combustion stops is the change in the rotational resistance. It is preferable to determine whether or not it depends on.

  FIG. 11 is a flowchart showing a correction control routine for the target combustion stop rotational speed range A. This correction control routine is a routine that is stored in advance in the ROM of the ECU 17, and is a routine that the ECU 17 executes after the execution of the stop position control routine is completed.

  In the correction control routine of FIG. 11, the ECU 17 first obtains the post-combustion engine speed Neaf and the actual stop position Pca of the crankshaft 15 in S401. The post-combustion engine speed Neaf and the stop position Pca are acquired during the execution of the stop position control routine.

  In S402, the ECU 17 determines whether or not the engine speed Neaf after combustion stop is higher than the allowable speed range. Specifically, in FIG. 12, the ECU 17 determines whether or not a point determined by the post-combustion engine speed Neaf and the stop position Pca belongs to a region R1.

  If an affirmative determination is made in S402, the ECU 17 proceeds to S403 and corrects the allowable rotation speed region to be high.

  On the other hand, if a negative determination is made in S402, the ECU 17 skips S403 and proceeds to S404. In S404, the ECU 17 determines whether or not the engine speed Neaf after combustion stop is lower than the allowable speed range. Specifically, in FIG. 12, the ECU 17 determines whether or not a point determined by the post-combustion engine speed Neaf and the stop position Pca belongs to a region R2.

  If an affirmative determination is made in S404, the ECU 17 proceeds to S405 and corrects the allowable rotation speed region to be low.

  On the other hand, if a negative determination is made in S404, the ECU 17 skips S405 and proceeds to S406. In S406, the ECU 17 determines whether or not the actual stop position Pca of the crankshaft 15 is within the target crank angle range.

  If an affirmative determination is made in S406, the ECU 17 ends the execution of this routine. On the other hand, if a negative determination is made in S406, the ECU 17 proceeds to S407.

  In S407, the ECU 17 determines whether or not the post-combustion engine speed Neaf belongs to an allowable speed range. Specifically, the ECU 17 determines whether or not a point determined by the post-combustion engine speed Neaf and the stop position Pca in FIG. 12 belongs to an allowable speed range.

  If a negative determination is made in S407, the ECU 17 ends the execution of this routine. On the other hand, when an affirmative determination is made in S407, the ECU 17 proceeds to S408.

  In S408, the ECU 17 determines whether or not the stop position Pca is before the target crank angle range. Specifically, the ECU 17 determines whether or not a point determined by the post-combustion engine speed Neaf and the stop position Pca in FIG. 12 belongs to the region R3.

  If an affirmative determination is made in S408, the ECU 17 proceeds to S409 and corrects the target combustion stop rotational speed range to be higher.

On the other hand, if a negative determination is made in S408 (that is, if the point determined by the engine speed Neaf after combustion stop and the stop position Pca in FIG. 12 belongs to the region R4), the ECU 17 proceeds to S410, Correction is made so that the target combustion stop rotational speed range is lowered.

  As described above, when the ECU 17 executes the correction control routine of FIG. 11, the estimation means and the correction means according to the present invention are realized. As a result, it is possible to stop the crankshaft 15 in the target crank angle range even when the magnitude of the rotational resistance changes due to individual differences of the internal combustion engine 1 or changes with time.

1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. It is a figure which shows the correlation with the combustion stop rotation speed when the rotation resistance of a crankshaft is constant, and the stop position of a crankshaft. 3 is a timing chart illustrating an execution procedure of rotational speed control in the first embodiment. It is a figure which shows the 1st example from which a combustion stop rotation speed deviates from a target combustion stop rotation speed area when an engine speed is in a transient state. It is a figure which shows the 2nd example from which a combustion stop rotation speed deviates from a target combustion stop rotation speed area when an engine speed is in a transient state. 3 is a flowchart illustrating a rotation speed control routine according to the first embodiment. It is a figure which shows the relationship between reference | standard intake air amount and predetermined amount (DELTA) Ti. 7 is a flowchart showing a rotation speed control routine in Embodiment 2. It is the figure which showed a mode that peak timing changed with ignition timing. 10 is a flowchart illustrating a rotation speed control routine according to a fourth embodiment. FIG. 10 is a flowchart showing a correction control routine for a target combustion stop rotation speed range in Embodiment 5. FIG. It is a figure which prescribed | regulated the correction | amendment area | region defined from the engine speed after a combustion stop, and the stop position of a crankshaft.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 6 ... Throttle valve 7 ... Air flow meter 12 ... Spark plug 15 ... Crankshaft 16 ... Crank position sensor 17 ... ECU

Claims (8)

In the stop position control system for an internal combustion engine that stops the crankshaft in a target crank angle range by stopping the combustion of the internal combustion engine when the engine speed is in a predetermined speed range,
Holding means for holding the throttle opening at a predetermined opening when the internal combustion engine operation stop condition is satisfied;
When the internal combustion engine operation stop condition is satisfied, first, the ignition timing is retarded by a predetermined amount or more to lower the engine rotational speed from the predetermined rotational speed range, and then the engine rotational speed falls below the predetermined rotational speed range. and control means for executing the rotational speed control for advancing the ignition timing to at the engine speed to converge to the predetermined speed range,
An internal combustion engine stop position control system comprising:   2. The stop position control system for an internal combustion engine according to claim 1, wherein the control means maintains a state where the ignition timing is retarded by a predetermined amount or more for a predetermined time.   3. The control means according to claim 1, wherein the control means acquires a maximum value of the engine speed in an expansion stroke of the cylinder and performs the rotation speed control so that the acquired maximum value converges in the predetermined speed range. A stop position control system for an internal combustion engine.   4. The stop position control system for an internal combustion engine according to claim 3, wherein the control means limits an ignition timing during execution of the rotational speed control within a predetermined range.   5. The internal combustion engine stop according to claim 4, wherein the holding means corrects the predetermined opening when the engine speed does not converge to the predetermined speed range by adjusting the ignition timing within the predetermined range. Position control system.   6. The stop position of the internal combustion engine according to claim 1, wherein when the execution time of the rotation speed control exceeds a predetermined time, the control means immediately stops the operation of the internal combustion engine. Control system. In any one of Claims 1-6, the estimation means which estimates the magnitude | size of the rotational resistance of the said crankshaft,
Correction means for correcting the predetermined rotational speed range based on the magnitude of the rotational resistance estimated by the estimation means;
A stop position control system for an internal combustion engine, further comprising:   8. The stop position of the internal combustion engine according to claim 7, wherein the estimation means estimates the magnitude of the rotation resistance based on an engine speed in a predetermined crank angle range after combustion of the internal combustion engine is stopped. Control system.

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