JP5565279B2 - Engine start control device - Google Patents

Description

  The present invention provides an engine start control having a function of determining whether or not restart is successful when the engine is restarted in response to a restart request during a period when the engine rotation speed when the engine is stopped is decreased. It is an invention related to a device.

  In recent years, in an idle stop system (engine automatic stop / start control device), as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-330813), a period in which the engine rotation speed decreases immediately after the occurrence of an automatic stop request ( In order to enable the engine to be restarted quickly without waiting for the engine to stop when a restart request occurs during the "engine rotation descent period" (hereinafter referred to as the "engine rotation descent period"), a pinion that jumps into the ring gear on the engine side Equipped with a starter that can individually operate the actuator and the motor that rotates the pinion, and when a restart request occurs during the engine rotation drop period immediately after the automatic stop request occurs, energization of the starter motor is started. And rotate the pinion, and the rotation speed of the pinion and the engine rotation speed (ring gear rotation speed) At the timing when the deviation is within the predetermined value, the pinion actuator is operated, the pinion is jumped into the ring gear and meshed, the engine is cranked and restarted, and within a predetermined time from the start of cranking There is one in which it is determined whether or not the restart is successful depending on whether or not the engine rotation speed is equal to or higher than a predetermined start determination rotation speed (see Patent Document 2).

  Although not an idle stop system, as a method for detecting engine start failure, for example, as described in Patent Document 3 (Japanese Patent Application Laid-Open No. 2006-83781), the battery reference voltage when the starter is stopped and when the starter is driven In some cases, it is determined whether or not the engine has been successfully started based on whether or not the voltage difference from the measured battery voltage (battery voltage drop during starter driving) is greater than or equal to a predetermined value.

Japanese Patent Laying-Open No. 2005-330813 JP 2005-113781 A JP 2006-83781 A

  However, as in Patent Documents 1 and 2, in a system that determines whether restart has succeeded based on whether or not the engine rotational speed has become equal to or higher than the start determination rotational speed at restart, within a predetermined time from the start of cranking Since the success / failure of the restart is determined by whether or not the engine speed has exceeded the predetermined start determination rotation speed, it takes a long time to determine the success / failure of the restart. The success / failure judgment cannot be made. For this reason, when restart fails, the next restart cannot be performed quickly.

  Further, as in Patent Document 3, in a system for determining success / failure of restart based on the battery voltage decrease amount during starter driving, the battery voltage decrease amount during starter driving varies depending on the state of charge of the battery. There is a possibility of misjudging the success / failure of the start-up.

  Therefore, the problem to be solved by the present invention is that when restarting the engine in response to the restart request during the engine rotation descent period when stopping the engine, the success / failure determination of the restart is made faster and faster than before. It is an object to provide an engine start control device that can be performed with high accuracy.

In order to solve the above-described problems, the invention according to claim 1 is capable of individually operating a pinion actuator that engages a pinion by jumping into a ring gear connected to the crankshaft of the engine and a motor that rotationally drives the pinion. When a restart request is generated during a period when the engine rotation speed when the engine is stopped with the starter mounted (hereinafter referred to as “engine rotation drop period”), the pinion is jumped into the ring gear and engaged. In addition, in the engine start control device comprising starter control means for cranking and restarting the engine, engine rotation speed detection means for detecting engine rotation speed during the engine rotation drop period, and engine restart control means during the engine rotation drop period. assuming starting failure detection timing of the engine rotational speed detecting means And the engine speed predicting means for predicting the engine rotational speed at, detected by said engine rotational speed detecting means after the restart request occurs when restarting the engine in response to the restart request to the engine rotational descent period A restart success / failure determination means for determining success or failure of restart based on a deviation between an engine rotation speed detection value and an engine rotation speed prediction value predicted by the engine rotation speed prediction means is provided. .

In this configuration, when the engine is restarted in response to the restart request during the engine rotation descent period, the actual engine rotation speed detected value detected after the restart request is generated and the engine speed predicted on the assumption that the restart has failed. If the deviation from the predicted speed value is small, it can be determined that the restart has failed, and the success or failure of the restart can be determined more quickly and accurately than in the past.

In this case, the timing for predicting the engine rotational speed may be set at a predetermined crank angle, but the engine rotational speed decreases while pulsating at a cycle of TDC (compression top dead center) during the engine rotational decrease period. Therefore, as in claim 2, the engine rotation speed is predicted for each TDC during the engine rotation descent period, and restart is performed based on the deviation between the detected engine rotation speed for each TDC and the predicted engine rotation speed for each TDC. The success or failure may be determined. In this way, even if there is a situation in which the engine speed drops while pulsating at the TDC period during the engine speed drop period, the detected engine speed value and the engine speed at a constant timing synchronized with the pulsation. The deviation from the predicted value can be evaluated, and the influence of pulsation can be eliminated.

  Further, the restart success / failure judging means judges the success or failure of the restart by comparing the deviation between the engine rotational speed detection value and the engine rotational speed prediction value with a predetermined judgment threshold value. It is good to do so. In this way, the success or failure of restart can be determined by simple processing.

FIG. 1 is a schematic configuration diagram of an engine start control system according to Embodiment 1 of the present invention. FIG. 2 is a diagram showing a prediction result of the engine rotation descent trajectory predicted on the assumption that the restart has failed. FIG. 3 is a diagram for explaining a prediction calculation method of the engine rotation descending trajectory. FIG. 4 is a diagram illustrating a method for determining pinion drive timing. FIG. 5 is a time chart for explaining the difference between the detected value of the engine speed when the restart is successful and the predicted value of the engine speed when the restart fails. FIG. 6 is a time chart for explaining the behavior in which the detection error of the engine speed increases as the engine speed decreases. FIG. 7 is a flowchart showing the flow of processing of the engine rotation descent trajectory prediction routine of the first embodiment. FIG. 8 is a flowchart showing the flow of processing of the starter control routine of the first embodiment. FIG. 9 is a flowchart illustrating the flow of processing of the restart failure determination routine according to the first embodiment. FIG. 10 is a flowchart illustrating the flow of processing of the restart failure determination routine according to the second embodiment.

  Hereinafter, two embodiments 1 and 2 will be described which are embodied by applying the mode for carrying out the present invention to an engine automatic stop / start control system (idle stop system).

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of an engine automatic stop / start control system will be described with reference to FIG.

  The starter 11 is a so-called pinion push-out starter, and includes a motor 12, a pinion 13 that is rotationally driven by the motor 12, a pinion actuator 14 that pushes out the pinion 13, and the like. And can be operated individually. The pinion 13 is provided so as to be movable in the axial direction. The pinion actuator 14 is provided with a plunger 15 and a solenoid 16 that drives the plunger 15, and the driving force of the plunger 15 is transmitted to the pinion 13 via a lever 17 or the like.

  A relay 19 is provided between the battery 18 and the pinion actuator 14, and the ECU 20 (engine control circuit) turns on the relay 19 to turn on the energization of the pinion actuator 14 to move the plunger 15 in the pinion pushing direction. By moving the pinion 13, the pinion 13 is pushed out and engaged with the ring gear 23 connected to the crankshaft 22 of the engine 21.

  Further, a switching element 24 is provided between the battery 18 and the motor 12, and the ECU 20 controls on / off of the switching element 24 and duty-controls the energization of the motor 12, thereby controlling the rotation speed of the pinion 13. It comes to control.

  The engine 21 is provided with a crank angle sensor 25 (engine rotation speed detecting means) that outputs a crank pulse every time the crankshaft 22 rotates a predetermined crank angle (for example, 30 ° C. A), and based on the output interval of the crank pulse. Thus, the engine speed is calculated and the crank pulse is counted to detect the crank angle.

  The ECU 20 is composed mainly of a microcomputer, and controls the fuel injection amount and ignition timing of the engine 21 according to the engine operating state by executing various engine control programs stored in the built-in ROM.

  Further, the ECU 20 executes engine automatic stop / start control (so-called idle stop control) by executing an engine automatic stop / start control routine (not shown). In this automatic engine stop / start control, when the driver performs a deceleration operation (accelerator fully closed, brake operation, etc.) while the vehicle is running, the vehicle enters a predetermined deceleration state that may cause the vehicle to stop, or the vehicle is stopped. When the brake operation is continued, it is determined that an automatic stop request (idle stop request) has occurred, and combustion (fuel injection and / or ignition) of the engine 21 is stopped to automatically start the engine 21. Stop (idle stop).

  After that, it is determined that a restart request has occurred when the driver performs a preparation operation for starting the vehicle (brake release, operation of the shift lever to the drive range, etc.) or a start operation (depressing the accelerator, etc.). Then, the engine 21 is cranked by the starter 11 and the fuel injection is restarted and restarted. In addition, a restart request may be generated from a control system for in-vehicle devices such as a battery charge control system and an air conditioner.

The restart request may occur during a period in which the engine rotation speed decreases (hereinafter referred to as “engine rotation decrease period”) or may occur after the engine rotation has stopped.
When a restart request is generated after the engine has stopped rotating, the pinion actuator 14 is energized to engage the pinion 13 into the ring gear 23 on the engine 21 side, and then the motor 12 of the starter 11 is energized to the pinion 13. Is rotated to crank the engine 21 to restart and restart fuel injection.

  If no restart request is generated during the engine rotation descent period, the pinion actuator 14 is energized to supply the pinion 13 to the engine 21 in preparation for the next restart immediately before or immediately after the engine rotation is stopped. It is also possible to keep the pinion 13 engaged with the ring gear 23 on the engine 21 side until the next restart is completed.

  On the other hand, when a restart request is generated during the engine rotation drop period, the motor 12 of the starter 11 is energized to rotate the pinion 13, and the rotation speed of the pinion 13 and the engine rotation speed (the rotation speed of the ring gear 23). At a timing when the deviation becomes within a predetermined value, the pinion actuator 14 is operated to cause the pinion 13 to jump into and engage with the ring gear 23 to crank and restart the engine 21.

  At the time of this restart, when it is determined that the restart is completed, the energization to the motor 12 of the starter 11 is stopped, the energization to the pinion actuator 14 is stopped, and the pinion 13 is moved by a return spring (not shown). It is extracted from the ring gear 23 on the engine 21 side and returned to its original position.

  Further, the ECU 20 executes an engine rotation descent trajectory prediction routine shown in FIG. 7 to be described later, thereby predicting a trajectory (hereinafter referred to as “engine rotation descent trajectory”) at which the engine speed decreases when the engine 21 is automatically stopped. Further, by executing a starter control routine of FIG. 8 described later, the drive timing of the pinion 13 is determined based on the predicted data of the engine rotation descending trajectory.

Here, a method for predicting the engine rotation descent trajectory of this embodiment will be described.
In the following description, an example using a crank angle sensor 25 that outputs a crank pulse every 30 ° C. will be described. As a result, during the period when the engine rotation speed decreases during the automatic engine stop, the angular speed ω [rad / sec] is calculated by the following equation for every 30 ° C. when the crank pulse is input from the crank angle sensor 25 to the ECU 20.
ω = 30 × 2π / (360 × tp)
tp: Crank pulse interval [sec]

  From the above equation, the angular velocity ω [0, i-1] at a crank angle of 0 ° A after the TDC of the 180 ° A section [i-1] in the previous time, the angular velocity ω [30, i-1] at a crank angle of 30 ° A , Angular speed ω [60, i-1] with a crank angle of 60 ° C, angular speed ω [90, i-1] with a crank angle of 90 ° C, angular speed ω [120, i-1] with a crank angle of 120 ° C, An angular velocity ω [150, i-1] at an angle 150 ° C. and an angular velocity ω [0, i] at a crank angle 0 ° A after TDC in the current 180 ° A section [i] are calculated.

  Further, loss torque T [0-30, i-1] from crank angle 0 ° C to 30 ° A after TDC of the previous 180 ° C section [i-1], crank angle 30 ° A to 60 ° A Loss torque T [30-60, i-1], loss torque T [60-90, i-1] from crank angle 60 ° C. to 90 ° C., and loss torque T [ 90-120, i-1], loss torque T [120-150, i-1] from crank angle 120 ° C to 150 ° A, after TDC of crank angle 150 ° A to current 180 ° A section [i] The loss torque T [150-0, i-1] up to 0 ° C is calculated.

T [0-30, i-1] = − J · (ω [30, i-1] ² −ω [0, i-1] ² ) / 2
T [30-60, i-1] = −J ・ (ω [60, i-1] ² −ω [30, i-1] ² ) / 2
T [60-90, i-1] = −J · (ω [90, i-1] ² −ω [60, i-1] ² ) / 2
T [90-120, i-1] = − J · (ω [120, i-1] ² −ω [90, i-1] ² ) / 2
T [120-150, i-1] = − J · (ω [150, i-1] ² −ω [120, i-1] ² ) / 2
T [150-0, i-1] = − J · (ω [0, i] ² −ω [150, i-1] ² ) / 2

Here, J is the inertia of the engine 21. The calculated values of the loss torques T [0-30, i-1] to T [150-0, i-1] are updated and stored in the registers (see FIG. 3).
Then, at 30 ° C. A (current time) after TDC of the current 180 ° C. section [i], the angular velocity ω [30, i] is calculated, and the loss torque T [0-30, i] is calculated in the same manner. The loss torque T [0-30, i] is updated and stored in the register.

  After that, as shown in FIG. 3, the current 180 ° C. section [i-1] is used for the current 180 ° torque loss T [30-60, i-1] from the crank angle 30 ° A to 60 ° C. The predicted angular velocity ω ′ [60, i] of the crank angle 60 ° C. after TDC in the ° C interval [i] is calculated, and the predicted arrival time t [30 until the crank angle 30 ° A reaches 60 ° C. -60, i] is calculated, and the loss torque T [60-90, i-1] from the crank angle 60 ° C to 90 ° C in the previous 180 ° A section [i-1] and the predicted angular velocity ω are calculated. '[60, i] is used to calculate the predicted angular velocity ω' [90, i] of the crank angle 90 ° C after TDC in the current 180 ° C section [i] and from the crank angle 60 ° A to 90 ° C. The estimated arrival time t [60-90, i] until reaching ℃ A is calculated, and the loss torque T [from the crank angle 90 ℃ A to 120 ℃ A in the previous 180 ℃ A section [i-1] is calculated. 90-120, i-1] and above Using the predicted angular velocity ω ′ [90, i], the predicted angular velocity ω ′ [120, i] of the crank angle 120 ° C. after the TDC of the current 180 ° A section [i] is calculated, and the crank angle 90 ° C. The engine rotation descent trajectory is predicted by repeating the process of calculating the predicted arrival time t [90-120, i] from A to 120 ° C. A (see FIG. 2).

  This prediction calculation is executed using the time until the next crank pulse is input every time the crank pulse is input (every 30 ° C. A), and the prediction data of the engine rotation orbit is updated each time. If the calculation time until the next crank pulse is input has a margin, the engine rotation descent trajectory until the engine rotation stops is predicted, but if the calculation time is insufficient, the prediction calculation is interrupted halfway, The process proceeds to a new prediction calculation using the actual angular velocity at the next crank angle. It goes without saying that the prediction calculation may be performed by converting the angular velocity into the engine rotation speed.

  In the first embodiment, as shown in FIG. 4, when a restart request is generated during a period when the engine rotation speed when the engine 21 is automatically stopped, the starter 11 is supplied to the motor 12 at that time. The energization is started to rotate the pinion 13 to predict the rotation ascending trajectory of the pinion 13, and the timing at which the difference between the prediction data of the engine rotation descending trajectory and the prediction data of the rotation ascending trajectory of the pinion 13 reaches within a predetermined value Is predicted as the drive timing of the pinion 13.

Here, the method for predicting the rotation rising trajectory of the pinion 13 is, for example, using the following model formula in which the rotation rising trajectory of the pinion 13 is modeled by a first-order lag model of a predetermined time constant τ. Can be predicted.
Np = Npmax {1-exp (-t / τ)}
Np: rotational speed of the pinion 13
Npmax: Maximum rotation speed of the pinion 13
t: Elapsed time

  Furthermore, in the first embodiment, as shown in FIG. 5, assuming that the engine 21 has been restarted during the engine rotation descent period when the engine 21 is automatically stopped, the engine rotation speed (angular speed) is predicted by the above-described method, When restarting in response to a restart request during the engine rotation descent period, the deviation between the engine rotation speed detection value detected based on the output pulse interval of the crank angle sensor 25 and the engine rotation speed prediction value predicted by the above method is calculated. It is determined whether or not the restart has failed by comparing with a predetermined determination threshold value, and as a result, when it is determined that the restart has failed, a control for cranking and restarting the engine 21 again is executed. ing.

  In this case, the timing for predicting the engine rotational speed may be set at a predetermined crank angle, but the engine rotational speed decreases while pulsating at a cycle of TDC (compression top dead center) during the engine rotational decrease period. Therefore, in the first embodiment, when restarting in response to the restart request during the engine rotation descent period, the deviation between the engine rotation speed detection value detected for each TDC and the engine rotation speed prediction value predicted for each TDC. Is compared with a predetermined determination threshold value to determine whether or not the restart has failed. In this way, even if there is a situation in which the engine speed drops while pulsating at the TDC period during the engine speed drop period, the detected engine speed value and the engine speed at a constant timing synchronized with the pulsation. The deviation from the predicted value can be compared with a predetermined determination threshold, and the influence of pulsation can be eliminated.

  In addition, the determination threshold value used for determining the restart failure may be a constant value set in advance for simplification of the arithmetic processing. However, as shown in FIG. 6, the engine rotation speed decreases as the engine rotation speed decreases. Detection error increases, and the deviation between the actual engine speed and the detection value increases.

  Therefore, in the first embodiment, a map for calculating a determination threshold value using the engine speed as a parameter is created in advance based on experimental data, simulation results, and the like, and stored in a nonvolatile storage medium such as a ROM of the ECU 20. In addition, the determination threshold value is calculated from the map based on the detected engine speed. Thereby, the determination threshold value can be appropriately set according to the detection error that increases as the engine speed decreases.

Since the engine speed decreases according to the elapsed time after the restart request occurs, even if the determination threshold is set according to the elapsed time after the restart request occurs, the engine speed decreases. The determination threshold value can be appropriately set according to the increasing detection error.
The restart control according to the first embodiment described above is executed by the ECU 20 according to the routines shown in FIGS. The processing contents of these routines will be described below.

[Engine rotation descent trajectory prediction routine]
The engine rotation descent trajectory prediction routine of FIG. 7 is repeatedly executed at a predetermined cycle during engine operation (during the power-on period of the ECU 20), and serves as engine rotation speed prediction means in the claims. When this routine is started, first, at step 101, it is determined whether or not the idle stop is being performed. If the idle stop is not being performed, the present routine is terminated without performing the subsequent processing.

On the other hand, if it is determined in step 101 that the engine is idling, the process proceeds to step 102, where it is determined whether or not a crank pulse is input to the ECU 20 from the crank angle sensor 25 and waits until the crank pulse is input. To do. Each time a crank pulse is input, the process proceeds to step 103 to calculate an angular velocity ω when the crank pulse is input this time.
ω = 30 × 2π / (360 × tp)
tp: Crank pulse interval [sec]

  Thereafter, the process proceeds to step 104, and the loss torque of the engine 21 stored in the register is read. As this loss torque, the loss torque calculated at the time of crank pulse input before 150 ° C. A and stored in the register is used. Thereafter, the process proceeds to step 105, where the predicted angular velocity ω ′ at the input timing of the next crank pulse is calculated using the loss torque, and the predicted arrival time t until the input timing of the next crank pulse is calculated.

  Thereafter, the routine proceeds to step 106, where it is determined whether or not the prediction of the engine rotation descent trajectory until the engine rotation is stopped is made depending on whether or not the predicted angular velocity ω ′ at the input timing of the next crank pulse is 0 or less. judge. If it is determined in step 106 that the predicted angular velocity ω ′ is not less than or equal to 0, the process proceeds to step 107, the loss torque of the engine 21 is calculated and stored in the register, and the processing of steps 104 and 105 described above is repeated. Using the loss torque and the predicted angular velocity ω ′, the process of calculating the predicted angular velocity ω ′ and the predicted arrival time t at the input timing of the next crank pulse is repeated.

  The predicted angular velocity ω ′ and predicted arrival time t every 30 ° C. are repeated many times, and when the predicted angular velocity ω ′ becomes 0 or less, the engine rotation descent trajectory until the engine rotation is stopped is predicted. When it is determined that the process has been completed, the process returns to step 102 and waits until the next crank pulse is input. Thus, every time a crank pulse is input, a prediction calculation of the engine rotation descent trajectory until the engine rotation is stopped is performed.

  If the calculation time until the next crank pulse is input is shorter than the time required for the prediction calculation of the engine rotation descent trajectory until the engine rotation stops, the prediction calculation is interrupted and the next calculation is interrupted. The process proceeds to a new prediction calculation using the actual angular velocity ω at the crank angle.

[Starter control routine]
The starter control routine of FIG. 8 is repeatedly executed at a predetermined cycle during the power-on period of the ECU 20, and serves as starter control means in the claims. When this routine is started, first, at step 201, it is determined whether or not a restart request has occurred. If no restart request has occurred, this routine is terminated without performing the subsequent processing. To do.

  Thereafter, when a restart request is generated, the process proceeds to step 202 to determine whether or not the engine rotation is decreasing (whether or not the engine rotation is stopped). If it is determined that the pinion actuator 14 is present, the pinion actuator 14 is energized to cause the pinion 13 to jump into the ring gear 23. In the next step 209, the motor 12 is energized after a predetermined delay time and the pinion 13 is energized. Rotate. Thereby, the engine 21 is cranked and restarted.

  On the other hand, if it is determined in step 202 that the engine speed is decreasing, the process proceeds to step 203 to determine whether or not energization of the motor 12 is permitted, for example, if the engine speed is equal to or lower than a predetermined speed. It is determined whether or not there is an electric current, and if energization to the motor 12 is not permitted, the process waits until energization to the motor 12 is permitted. Thereafter, when energization of the motor 12 is permitted, the process proceeds to step 204, where energization of the motor 12 is started and the pinion 13 is rotated.

  Thereafter, the process proceeds to step 205, and the rotation ascending trajectory of the pinion 13 is predicted using a model formula obtained by modeling the rotation ascending trajectory of the pinion 13 with a first-order lag model. Then, in the next step 206, the timing (pinion) at which the difference between the predicted data of the engine rotation descent trajectory calculated by the engine rotation descent trajectory prediction routine of FIG. 13), and waits until the timing is reached. Thereafter, when the timing (the driving timing of the pinion 13) at which the difference between the prediction data of the engine rotation descending trajectory and the prediction data of the rotation ascending trajectory of the pinion 13 reaches a predetermined value (drive timing of the pinion 13) is reached, the process proceeds to step 207. Is energized to cause the pinion 13 to jump into and engage with the ring gear 23, and the engine 21 is cranked and restarted.

  If the restart request is not generated during the engine rotation descent period when the engine 21 is automatically stopped, the noise level when the pinion is engaged is extremely low based on the predicted data of the engine rotation descent trajectory. What is necessary is just to determine the drive timing of the pinion 13 so that the pinion 13 jumps into and engages with the ring gear 23 at the timing when the engine rotation speed decreases to the rotation region.

[Restart failure judgment routine]
The restart failure determination routine of FIG. 9 is repeatedly executed at a predetermined cycle during engine operation (during power-on period of the ECU 20), and serves as restart success / failure determination means in the claims. When this routine is started, first, at step 301, it is determined whether or not the engine speed is decreasing due to idling stop. If the engine speed is not decreasing due to idling stop, the subsequent processing is not performed. This routine ends.

  On the other hand, if it is determined in step 301 that the engine speed is decreasing due to idle stop, the process proceeds to step 302, where it is determined whether a restart request has occurred. This routine is terminated without performing any processing.

  Thereafter, when a restart request is generated, the process proceeds to step 303 where it is assumed that the restart has failed, and using the calculation result of the engine rotation descent trajectory prediction routine of FIG. NEy (n + 1) is calculated.

  Thereafter, the process proceeds to step 304, and a determination threshold value used for determination of restart failure is calculated from a map or the like based on the engine rotational speed detection value NE (n + 1) of the current TDC. Thereafter, the routine proceeds to step 305, where the engine speed detection value NE (n + 1) of the next TDC is calculated based on the output pulse interval of the crank angle sensor 25.

  Thereafter, the process proceeds to step 306, where the deviation between the next engine speed detection value NE (n + 1) of the TDC and the engine speed prediction value NEy (n + 1) of the next TDC is smaller than the determination threshold value. If it is determined that the deviation is smaller than the determination threshold value, the process proceeds to step 307, where it is determined that the restart has failed, and in the next step 308, the starter control routine of FIG. Then, the control for cranking and restarting the engine 21 again is executed.

  On the other hand, in step 306, it is determined that the deviation between the detected engine speed NE (n + 1) of the next TDC and the predicted engine speed NEy (n + 1) of the next TDC is greater than or equal to the determination threshold value. If so, it is determined that the restart has not failed, and this routine is terminated.

  According to the first embodiment described above, the engine rotation speed is predicted for each TDC on the assumption that the engine 21 is automatically restarted during the engine rotation drop period when the engine 21 is automatically stopped, and a restart request is issued during the engine rotation drop period. When the engine is restarted according to the above, the deviation between the engine rotation speed detection value detected based on the output pulse interval of the crank angle sensor 25 and the engine rotation speed prediction value predicted by the above method is compared with a predetermined determination threshold value. Thus, it is determined whether or not the restart has failed. As a result, when it is determined that the restart has failed, the control for cranking and restarting the engine 21 again is executed. Can be performed more quickly and accurately than before, and if the restart fails, the next restart can be performed quickly, improving the recoverability when the restart fails. It can be.

  In the first embodiment, the determination threshold value used for determining the restart failure is set. However, the determination threshold value used for determining the restart success is set, and the engine rotation speed detection value and the engine rotation speed prediction value are set. Whether or not the restart is successful may be determined based on whether or not the deviation is greater than or equal to the determination threshold value.

  The method for predicting the engine rotation descent trajectory is not limited to the method of the first embodiment. For example, based on the history data of the engine rotation speed in the section from the previous TDC to the current TDC, The engine rotation descent trajectory in the section up to the next TDC may be predicted. Also, the engine rotation descent trajectory may be predicted for each section of the timing at which the same crank angle is used instead of the TDC for the engine rotation descent trajectory prediction.

  In the first embodiment, the difference between the detected engine speed and the predicted engine speed is compared with the determination threshold value to determine the restart failure (or success), but the second embodiment of the present invention. Then, by executing the restart failure determination routine of FIG. 10, the engine rotation speed after cranking is started without performing the process of predicting the engine rotation speed on the assumption that the restart has failed during the engine rotation drop period. The restart failure is determined only by the detection amount increase amount (or increase rate). Other matters are the same as those in the first embodiment.

  Hereinafter, the processing content of the restart failure determination routine of FIG. 10 executed in the second embodiment will be described. The restart failure determination routine of FIG. 10 is repeatedly executed at a predetermined cycle during engine operation (during the power-on period of the ECU 20), and serves as restart success / failure determination means in the claims. When this routine is started, first, at step 401, it is determined whether or not the engine speed is being lowered due to idle stop. If the engine speed is not being lowered due to idle stop, the subsequent processing is not performed. This routine ends.

  On the other hand, if it is determined in step 401 that the engine speed is decreasing due to idle stop, the process proceeds to step 402, where it is determined whether a restart request has occurred. This routine is terminated without performing any processing.

  Thereafter, when a restart request is generated, the process proceeds to step 403 to calculate an increase amount ΔNE (or an increase rate) of the engine rotation speed detection value after the cranking starts. It is determined whether or not the increase amount ΔNE (or increase rate) of the engine rotation speed detection value is less than a predetermined determination threshold value, and it is determined that the increase amount ΔNE (or increase rate) is less than the determination threshold value. If so, the process proceeds to step 405, where it is determined that the restart has failed. In the next step 406, the starter control routine of FIG. 8 is executed, and the engine 21 is again cranked and restarted.

  On the other hand, if it is determined in step 404 above that the increase amount ΔNE (or increase rate) of the engine rotation speed detection value after the start of cranking is greater than or equal to the determination threshold value, it is determined that the restart has not failed, and this routine is performed. Exit.

  According to the second embodiment described above, the increase amount ΔNE (or the increase rate) of the engine rotation speed detection value after the start of cranking is compared with the determination threshold value to determine whether or not the restart has failed. Therefore, even if the process for predicting the engine rotation speed is not performed on the assumption that the restart has failed during the engine rotation descent period, the determination of the restart failure is made only by the increase amount ΔNE (or the increase rate) of the engine rotation speed detection value. This can be performed, and the calculation process for determining the restart failure can be greatly simplified.

  In the second embodiment, the determination threshold value used for determining the restart failure is set. However, the determination threshold value used for determining the restart success is set, and the engine rotation speed detection value after the start of cranking is set. Whether the restart is successful may be determined based on whether the increase amount ΔNE (or the increase rate) is equal to or greater than the determination threshold value.

In the first and second embodiments, whether or not the restart is successful may be determined based on whether or not the engine rotation speed detection value exceeds the start completion determination threshold value.
In the first and second embodiments, when a restart request is generated during the engine rotation drop period, the pinion actuator 14 is operated at a predetermined timing while starting the motor 12 of the starter 11 and rotating the pinion 13. Since the pinion 13 jumps into and engages with the ring gear 23, the difference between the pinion rotation speed and the engine rotation speed (ring gear rotation speed) is reduced even in a region where the engine rotation speed is relatively high. Can be surely jumped into the ring gear 23 to engage with each other.

  However, the present invention is not limited to this, and when a restart request is generated during the engine rotation descent period, the motor 12 is started after the pinion 13 jumps into the ring gear 23 and meshes with it or during the meshing. Then, the pinion 13 may be rotationally driven to restart the engine 21. If the engine rotation speed is reduced to some extent, the difference from the engine rotation speed (ring gear rotation speed) is small without rotating the pinion 13, so that the pinion 13 can be engaged with the ring gear 23.

  In this case, for example, when a restart request is generated in a region where the engine rotation speed is equal to or higher than a predetermined rotation speed during the engine rotation drop period, the pinion 13 is started at a predetermined timing while starting the motor 12 of the starter 11 and rotating the pinion 13. When the actuator 14 is operated to cause the pinion 13 to jump into the ring gear 23 and mesh with the pinion 13 to restart the engine 21, on the other hand, when a restart request is generated in a region where the engine rotational speed has fallen below a predetermined rotational speed, the pinion 13 The motor 12 may be started and the pinion 13 may be rotationally driven to restart the engine 21 after jumping into the ring gear 23 and meshing.

  In addition, the present invention is not limited to the first and second embodiments. For example, the present invention can be applied in the same manner even when the interval between the crank pulses output from the crank angle sensor 25 is other than 30 ° C., Needless to say, the present invention can be implemented with various modifications such as being applicable to a vehicle not equipped with an idle stop system.

  DESCRIPTION OF SYMBOLS 11 ... Starter, 12 ... Motor, 13 ... Pinion, 14 ... Pinion actuator, 20 ... ECU (starter control means, engine rotational speed prediction means, restart success / failure judgment means), 21 ... Engine, 22 ... Crankshaft, 23 ... Ring gear 25 ... Crank angle sensor (engine speed detection means)

Claims (3)

A starter capable of individually operating a pinion actuator that engages and engages a pinion into a ring gear connected to an engine crankshaft and a motor that rotationally drives the pinion are mounted, and the engine rotation speed when stopping the engine is Starter control means for restarting the engine by cranking the pinion into the ring gear and engaging it when a restart request is generated during the descent period (hereinafter referred to as “engine rotation descent period”); In the engine start control device provided,
Engine rotation speed detection means for detecting engine rotation speed during the engine rotation descent period;
Engine rotation speed prediction means for predicting engine rotation speed at the detection timing of the engine rotation speed detection means on the assumption of restart failure during the engine rotation drop period;
When the engine is restarted in response to the restart request during the engine rotation drop period, the engine rotation speed detection value detected by the engine rotation speed detection means after the restart request is generated and predicted by the engine rotation speed prediction means An engine start control device comprising: restart success / failure determining means for determining success or failure of restart based on a deviation from the predicted engine rotation speed value. The engine rotation speed prediction means predicts the engine rotation speed for each TDC during the engine rotation drop period,
The restart success / failure determining means determines success or failure of restart based on a deviation between a detected engine rotation speed value for each TDC after the restart request is generated and an estimated engine rotation speed value for each TDC. The engine start control device according to claim 1.   The restart success / failure determining means determines the success or failure of the restart by comparing a deviation between the engine rotation speed detection value after the restart request is generated and the engine rotation speed prediction value with a predetermined determination threshold value. The engine start control device according to claim 1 or 2, wherein

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