JP2006207538A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to always ignite at ideal timing even under a situation of large rotation speed fluctuation in relation to an ignition timing control device for an internal combustion engine. <P>SOLUTION: This device acquires information relating to an operation condition of the internal combustion engine including rotation speed at intake valve closing timing or predetermined timing after valve closure, and calculates torque acting on a crank shaft of the internal combustion engine at information acquisition timing based on acquired operation condition information. Change of rotation speed from information acquisition timing to predetermined virtual ignition timing is estimated based on acquired operation condition information and torque calculated based on the same. Target ignition timing is established based on estimated rotation speed at virtual ignition timing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly, to a control device suitable for use in controlling ignition timing in a situation where the fluctuation of the rotational speed is large, such as idling, sudden acceleration / deceleration, and shift change.

  In conventional ignition timing control of an internal combustion engine, a target ignition timing is determined from an operating state including the engine speed at the initial stage of the compression stroke, and a timer set time (absolute time) from a predetermined reference time is determined from the determined target ignition timing. ) Is calculated. Then, the ignition timer is started at the reference time, and ignition by the spark plug is performed when the calculated timer set time has elapsed. Although the above timer setting time depends on the engine speed, in the conventional ignition timing control, the timer setting time is calculated while being fixed to the engine speed at the time of determination of the target ignition timing.

  According to the above-described conventional ignition timing control, an accurate target ignition timing can be set in a steady state where the engine speed fluctuation is small, and the ignition plug is ignited according to the set target ignition timing. be able to. However, in a situation where the engine speed fluctuation is large, such as during idling, the engine speed after the calculation of the timer setting time is not constant, so the actual ignition timing and target ignition timing controlled by the timer setting time There may be a gap between the two. That is, in the conventional ignition timing control, there is a possibility that the ignition cannot be performed according to the target ignition timing depending on the fluctuation state of the engine speed.

  Further, in a situation where the engine speed varies greatly, there may be a deviation between the engine speed at the actual ignition timing and the engine speed at the time when the target ignition timing is set. Since the target ignition timing is set based on the engine speed before the fluctuation, even if it can be ignited according to the target ignition timing, it cannot be ignited at an ideal ignition timing according to the engine speed. .

  As described above, in the conventional ignition timing control, the target ignition timing is set based on the engine speed at a time earlier than the ignition timing, and the timer setting time for igniting the spark plug is determined. In the situation where the rotation speed fluctuated, ignition could not be performed at an ideal ignition timing. Deviation from the ideal ignition timing leads to a decrease in generated torque, which may lead to engine stall during idling. Therefore, there is a need for an ignition timing control technique that can always perform ignition at an ideal ignition timing even when the engine speed is fluctuating during idling or the like.

Conventionally, various control techniques have been proposed for techniques for predicting changes in the rotational speed and controlling the ignition timing based on the predicted rotational speed. For example, in the control device described in Patent Document 1, a change in engine rotation is predicted using the current rotation cycle and a cycle change rate obtained from the previous rotation cycle, and this corresponds to the next ignition timing based on the prediction. The rotational speed at the crank angle position is estimated. Then, the target ignition timing is set based on the estimated rotation speed, and the time until the ignition plug is ignited from a predetermined crank angle position is calculated backward based on the set target ignition timing.
Japanese Patent No. 2832264

  However, the engine speed does not always change at the same cycle change rate as the past cycle change rate. For example, when a load of an auxiliary machine such as an alternator is suddenly turned on, the engine speed decreases regardless of the past cycle change rate. For this reason, with the technique described in Patent Document 1, the target ignition timing cannot be set based on accurate prediction of the engine speed, and the ignition plug can be ignited according to the set target ignition timing. It may not be possible. That is, even when the technique described in Patent Document 1 is used, it is difficult to perform ignition at an ideal ignition timing in a situation where the fluctuation of the engine speed is large.

  The present invention has been made in order to solve the above-described problems, and is an internal combustion engine that can always perform ignition at an ideal ignition timing even in a situation where fluctuations in engine speed are large. An object is to provide an ignition timing control device.

In order to achieve the above object, a first invention is an ignition timing control device for an internal combustion engine,
Information acquisition means for acquiring information related to the operating state of the internal combustion engine including the number of revolutions at the time of closing of the intake valve or a predetermined time after closing;
Torque calculating means for calculating torque acting on the crankshaft of the internal combustion engine at the time of information acquisition based on the acquired operating state information;
A rotation speed prediction means for predicting a change in the rotation speed from the information acquisition time point to a predetermined virtual ignition timing based on the acquired operating state information and the torque calculated by the torque calculation means;
Target ignition timing setting means for setting a target ignition timing based on the number of revolutions predicted in the virtual ignition timing;
It is characterized by having.

According to a second invention, in the first invention, a timer set time from a predetermined reference time to ignition by a spark plug is calculated from the change in the rotation speed predicted by the rotation speed prediction means and the target ignition timing. Timer setting time calculating means to perform,
Spark plug driving means for performing ignition by the spark plug when the timer set time has elapsed from the reference time;
It is characterized by having.

A third invention is an ignition timing control device for an internal combustion engine in order to achieve the above object,
Information acquisition means for acquiring information related to the operating state of the internal combustion engine, including the number of revolutions at the time of closing of the intake valve or at a predetermined time after closing;
Torque calculating means for calculating torque acting on the crankshaft of the internal combustion engine at the time of information acquisition based on the acquired operating state information;
A rotation speed prediction means for predicting a change in the rotation speed from the information acquisition time point to a predetermined target ignition timing based on the acquired operating state information and the torque calculated by the torque calculation means;
Timer setting time calculation means for calculating a timer setting time from a predetermined reference time point to ignition by an ignition plug from the change in the rotation speed predicted by the rotation speed prediction means and the target ignition timing;
Spark plug driving means for performing ignition by the spark plug when the timer set time has elapsed from the reference time;
It is characterized by having.

  In a fourth aspect based on any one of the first to third aspects, the rotational speed prediction means initially sets the rotational speed acquired by the information acquisition means and the torque calculated by the torque calculation means. And a change in the number of revolutions after the information acquisition time is predicted based on the correlation between the number of revolutions and the torque acting on the crankshaft.

  According to the first aspect of the present invention, it is possible to accurately predict a change in the rotational speed from the information acquisition time point to the virtual ignition timing from the information regarding the operating state of the internal combustion engine including the rotational speed and the torque acting on the crankshaft. . Since the target ignition timing is set based on this accurate prediction of the rotational speed, the target ignition timing can be set to an ideal ignition timing according to the rotational speed even in a situation where the rotational speed varies greatly. It becomes possible.

  Furthermore, according to the second aspect of the invention, since the timer set time from the reference time point to the ignition by the spark plug is set based on the accurate prediction of the change in the rotation speed, even if the fluctuation of the rotation speed is large, Thus, it is possible to prevent the actual ignition timing from deviating from the target ignition timing, and it is possible to always perform ignition at an ideal ignition timing corresponding to the rotational speed.

  According to the third aspect of the invention, it is possible to accurately predict a change in the rotational speed from the information acquisition time point to the virtual ignition timing based on the information related to the operating state of the internal combustion engine including the rotational speed and the torque acting on the crankshaft. Can do. Since the timer setting time from the reference time to ignition by the spark plug is set based on this accurate prediction of the rotational speed, the actual ignition timing deviates from the target ignition timing even in a situation where the rotational speed varies greatly This can be prevented, and ignition can always be performed at the target ignition timing.

  According to the fourth aspect of the invention, since the change in the rotation speed is predicted based on the correlation between the rotation speed and the torque acting on the crankshaft, the change in the rotation speed can be achieved even in a situation where the rotation speed is likely to fluctuate greatly. Can be predicted very accurately.

Hereinafter, embodiments 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 (hereinafter simply referred to as an engine) to which an ignition timing control device as Embodiment 1 of the present invention is applied. The present invention can be applied to, for example, a spark ignition type four-cylinder engine. The engine according to the present embodiment includes a cylinder block 6 in which a piston 8 is disposed, and a cylinder head 4 assembled to the cylinder block 6. A space from the upper surface of the piston 8 to the cylinder head 4 forms a combustion chamber 10, and an intake port 18 and an exhaust port 20 are formed in the cylinder head 4 so as to communicate with the combustion chamber 10. An intake valve 12 for controlling the communication state between the intake port 18 and the combustion chamber 10 is provided at a connection portion between the intake port 18 and the combustion chamber 10, and an exhaust gas is provided at a connection portion between the exhaust port 20 and the combustion chamber 10. An exhaust valve 14 for controlling the communication state between the port 20 and the combustion chamber 10 is provided. A spark plug 16 is attached to the cylinder head 4 so as to protrude from the top of the combustion chamber 10 into the combustion chamber 10.

  An intake passage 30 for introducing fresh air into the combustion chamber 10 is connected to the intake port 18 of the cylinder head 4. An air cleaner 32 is provided at the upstream end of the intake passage 30, and fresh air is taken into the intake passage 30 via the air cleaner 32. An air flow meter 56 for detecting the intake amount of fresh air is disposed downstream of the air cleaner 32. A downstream portion of the intake passage 30 is branched for each cylinder (for each intake port 18), and a surge tank 34 is provided at the branched portion. An electronically controlled throttle valve 36 is disposed upstream of the surge tank 34 in the intake passage 30. The throttle valve 36 is provided with a throttle sensor 54 for detecting the opening degree. Although not shown, the throttle valve 36 is provided with an ISC valve for adjusting the intake air amount during idling. In the vicinity of the intake port 18 of the intake passage 30, an injector 38 for injecting fuel is provided for each cylinder.

  The engine according to the present embodiment includes an ECU (Electronic Control Unit) 50 as a control device. Various devices such as the injector 38, the throttle valve 36, and the spark plug 16 are connected to the output side of the ECU 50. In addition to the air flow meter 56 and the throttle sensor 54 described above, various sensors such as a crank angle sensor 52 that detects the rotation angle of the crankshaft 24 are connected to the input side of the ECU 50. The crank angle sensor 52 is a sensor that outputs a signal every time the crankshaft 24 rotates by a certain angle. The ECU 50 drives each device according to a predetermined control program based on the output of each sensor.

  FIG. 2 is a flowchart showing the contents of engine ignition timing control executed by the ECU 50 in the present embodiment. The ignition timing control routine shown in FIG. 2 is executed for each cycle of each cylinder. For example, when the engine according to this embodiment is a four-cylinder engine, this routine is periodically executed every 180 ° CA.

  In the first step 100 of this routine, it is determined whether or not the ignition switch is on. If the ignition switch is still off, this routine is not started. Further, when the ignition switch is turned off during execution of this routine, this routine ends. If the ignition switch is on, in step 102, the engine speed (the number of revolutions per minute) Ne is acquired. The engine speed Ne can be calculated by processing the crank angle signal from the crank angle sensor 52.

  In the next step 104, it is determined whether or not the acquired engine speed Ne is zero. If the engine speed Ne is not zero, it can be determined that the engine has started. When the engine is started, the routine proceeds to step 106, where the throttle opening degree TA detected by the throttle sensor 54 is acquired.

  In the next step 108, it is determined whether or not the throttle opening degree TA is zero. In the engine according to the present embodiment, the amount of intake air during idling is adjusted by an ISC valve (not shown). For this reason, when the throttle opening degree TA is zero in a state where the engine is started, it can be determined that the engine is in an idling state. In the idling state, the engine rotational speed Ne is likely to fluctuate greatly, and it has been difficult to obtain an ideal ignition timing according to the rotational speed in the conventional ignition timing control. Therefore, in this routine, the target ignition timing is set by the processing after step 110 and the spark plug 16 is operated so that ignition can be performed at an ideal ignition timing even during idling. Yes.

  First, at step 110, the crank angle CA is acquired from the crank angle signal from the crank angle sensor 52. In the next step 112, it is determined whether or not the acquired crank angle CA is a crank angle θivc corresponding to the closing timing of the intake valve 12 of the cylinder. When the intake valve 12 is provided with a variable valve timing mechanism, θivc is changed in accordance with a change in valve timing. Until the crank angle CA reaches θivc, the processing of steps 100 to 112 is repeatedly executed.

  If the crank angle CA coincides with θivc, various information relating to the engine operating state is acquired at step 114. Specifically, the engine speed Neivc at θivc, the current load factor KL, the air-fuel ratio AF, the load factors α of the auxiliary machinery, the ignition timing SA, and the like. The load factor KL is obtained from the intake air amount detected by the air flow meter 56. The air-fuel ratio AF is a target air-fuel ratio, and a value obtained by dividing the intake air amount by the air-fuel ratio AF is the fuel injection amount from the injector 38. Examples of the auxiliary machines include an air conditioner, an alternator, a torque converter, and a power steering. Each load factor α of these auxiliary machines is obtained from the required output of each auxiliary machine. As the ignition timing SA, the target ignition timing set at the present time is read.

  In the next step 116, the value Tiivc of the indicated torque Ti acting on the crankshaft 24 at θivc is obtained. Here, it is assumed that the indicated torque at each crank angle is approximated by an average value of indicated torque from BDC to TDC (hereinafter referred to as average indicated torque). The average indicated torque Ti changes using the engine speed Ne, the load factor KL, the air-fuel ratio AF, and the ignition timing SA as parameters. The relationship between the average indicated torque Ti and each parameter is obtained in advance by calculation or the like, and is stored as a four-dimensional map with each parameter as an axis. Each graph (A) to (D) in FIG. 4 shows the relationship between the average indicated torque Ti and each parameter in the four-dimensional map. In step 116, the average indicated torque Tiivc corresponding to each parameter (engine speed Neivc, load factor KL, air-fuel ratio, ignition timing SA) at θivc is acquired from the above four-dimensional map.

  In step 118, the value Tfrivc of the mechanical friction Tfr of the engine body acting on the crankshaft 24 at θivc is obtained. The mechanical friction Tfr depends on the engine speed Ne. The relationship between the mechanical friction Tfr and the engine speed Ne is obtained in advance by calculation or the like, and is stored as a one-dimensional map with the engine speed Ne as an axis. FIG. 5 is a graph showing the relationship between the mechanical friction Tfr and the engine speed Ne in the one-dimensional map. In step 118, the mechanical friction Tfrivc corresponding to the engine speed Neivc at θivc is acquired from the one-dimensional map.

  In step 120, the value Tfrexivc of the load torque Tfrex of the auxiliary machines acting on the crankshaft 24 at θivc is obtained. The auxiliary machine load torque Tfrex changes using the engine speed Ne and the auxiliary machine load factor α as parameters. The relationship of the auxiliary machine load torque Tfrex to each parameter is obtained in advance by calculation or the like, and is stored as a two-dimensional map with each parameter as an axis. Each graph (A) and (B) in FIG. 6 shows the relationship between the auxiliary machine load torque Tfrex and each parameter in the two-dimensional map. In step 120, the accessory load torque Tfrexivc corresponding to each parameter (engine speed Neivc, accessory load factor α) at θivc is acquired from the two-dimensional map.

  The average indicated torque Ti, the mechanical friction Tf, and the auxiliary machine load torque Tfrex are all torques acting on the crankshaft 24, and the engine speed Ne is changed by the action of these torques. Further, as the engine speed Ne changes, the torques Ti, Tfr, Tfrex acting on the crankshaft 24 also change. In step 122, changes in the engine speed Ne and the torques Ti, Tfr, and Tfrex after θivc are predicted based on the correlation between the engine speed Ne and the torques Ti, Tfr, and Tfrex acting on the crankshaft 24. Finally, the engine rotational speed Netdc at the TDC is obtained.

  FIG. 3 is a flowchart showing a subroutine executed in step 122. In the first step 200 of the subroutine shown in FIG. 3, the average indicated torque Tiivc, the mechanical friction Tfrivc, and the auxiliary load torque Tfrexivc obtained in steps 116 to 120 are obtained as the average indicated torque Ti, the mechanical friction Tfr, and the auxiliary load torque, respectively. It is read as each initial value of Tfrex. Further, the engine speed Neivc at θivc is read as the initial value of the predicted engine speed Nepr, and θivc is also read as the initial value of the predicted crank angle θpr.

In the next step 202, the predicted engine speed Nepr after a minute time Δt is calculated from θivc by the following equation (1).
Nepr (k) = Nepr (k-1) + dNe / dt × Δt (1)
In the above equation (1), k is a counter indicating the number of executions of this step. Nepr (k) on the left side is a newly predicted engine speed predicted value Nepr this time, and Nepr (k-1) on the right side is the previous predicted engine speed Nepr. At the first execution of this step, the engine speed Neivc at θivc, which is the initial value of Nepr, is read as Nepr (k−1).

In the above formula (1), dNe / dt represents the rotational acceleration of the crankshaft 24. dNe / dt can be expressed by using the torque acting on the crankshaft 24 by the equation of motion shown in the following equation (2).
J × dNe / dt = Ti−Tfr−Tfrex (2)
In the above formula (2), J represents the moment of inertia (acquired value) of the engine crank / connecting rod system.

  By substituting the initial values of the average indicated torque Ti, mechanical friction Tfr and auxiliary load torque Tfrex read in step 200 into the above equation (2), the rotational acceleration dNe / of the crankshaft 24 after Δt from θivc dt can be calculated. Then, by substituting the calculated dNe / dt value into Equation (1), the predicted engine speed Nepr after a minute time Δt can be obtained from θivc. The above equation (2) represents the correlation between the engine speed Ne and the torques Ti, Tfr, Tfrex acting on the crankshaft 24.

In the next step 204, a predicted crank angle θpr after a minute time Δt is calculated from θivc by the following equation (3).
θpr (k) = θpr (k-1) + 360/60 × {Nepr (k) + Nepr (k-1)} / 2 × Δt (3)
In the above equation (3), θpr (k) on the left side is the newly predicted crank angle predicted value θpr this time, and θpr (k−1) on the right side is the previous crank angle predicted value θpr. At the first execution of this step, θivc, which is the initial value of θpr, is read as θpr (k−1). {Nepr (k) + Nepr (k-1)} / 2 on the right side shows the average engine speed from θpr (k-1) to θpr (k), and 360/60 multiplied by this is the engine It is a coefficient for converting the number of rotations to angular velocity. According to the above equation (3), the change in the engine rotation speed Ne predicted by the above equations (1) and (2) is reflected in the crank angle θ, so that the change in the crank angle θ after θivc is reflected. It can be predicted accurately. After execution of the process of step 204, the value of the counter k is incremented by one.

  In step 206, it is determined whether the predicted crank angle θpr calculated in step 204 has reached 0 deg., That is, whether the rotational position of the crankshaft 24 is TDC (compression TDC). If the predicted crank angle θpr has not reached 0 deg., The processing of steps 208, 210 and 212 is executed.

  In step 208, the predicted indicated engine speed Nepr calculated in step 202 and the average indicated torque Ti corresponding to the load factor KL, air-fuel ratio AF, and ignition timing SA acquired in step 114 are obtained from the aforementioned four-dimensional map. To be acquired. In step 210, the mechanical friction Tfr corresponding to the predicted engine speed Nepr calculated in step 202 is acquired from the one-dimensional map. In step 212, an auxiliary machine load torque Tfrex corresponding to the predicted engine speed Nepr calculated in step 202 and the auxiliary machine load factor α obtained in step 114 is obtained from the above-described two-dimensional map. In these steps 208, 210, and 212, values of torques Ti, Tfr, and Tfrex acting on the crankshaft 24 after a minute time Δt from θivc are calculated.

  After the processes of steps 208, 210, and 212, the process of step 202 is executed again. In step 202, the rotational acceleration dNe / dt of the crankshaft 24 is newly calculated by substituting the values of the torques Ti, Tfr, and Tfrex calculated in steps 208, 210, and 212 into the above equation (2). The Then, by substituting the calculated dNe / dt into the equation (1), the predicted engine speed Nepr after the minute time Δt has elapsed from the previous time (2 × Δt after θivc) is calculated.

  In step 204, the previous engine speed predicted value Nepr (k) newly calculated in step 202 and the predicted value Nepr (k-1) calculated in previous step 202 are calculated according to the above equation (3). The crank angle prediction value θpr after a lapse of a minute time Δt is calculated. Then, in step 206, it is determined whether or not the crank angle predicted value θpr calculated this time has reached 0 deg. If the predicted crank angle θpr has not yet reached 0 deg., The processing of steps 208, 210 and 212 is executed again.

  Until the crank angle predicted value θpr reaches deg., That is, until the rotational position of the crankshaft 24 reaches TDC, a loop including steps 202, 204, 206, 208, 210, and 212 is repeatedly executed. During this time, the values of the torques Ti, Tfr, Tfrex are calculated according to the predicted engine speed Nepr, and the predicted engine speed Nepr after a minute time Δt is calculated according to the values of the torques Ti, Tfr, Tfrex. The That is, based on the correlation between the engine speed Ne and the torques Ti, Tfr, Tfrex acting on the crankshaft 24, changes in the engine speed Ne and the torques Ti, Tfr, Tfrex are predicted every minute time Δt. To go.

  As a result of the determination in step 206, when the crank angle predicted value θpr has reached deg., That is, when the rotational position of the crankshaft 24 has reached TDC, the processing in step 214 is executed. In step 214, the predicted engine speed Nepr when the predicted crank angle θpr reaches deg. Is set as the engine speed Netdc at TDC. When step 214 is executed and the engine speed Netdc at TDC is obtained, step 122 of the ignition timing control routine shown in FIG. 2 ends.

  In the next step 124, the target ignition timing SAt is obtained based on the engine speed Netdc at TDC obtained in step 122. That is, in this routine, TDC is set as the virtual ignition timing, and the target ignition timing SAt is obtained based on the engine speed at this virtual ignition timing. Since the virtual ignition timing TDC and the actually set target ignition timing SAt are not far apart, the change in the engine speed from the TDC to the target ignition timing SAt can be regarded as small.

  The ECU 50 sets the target ignition timing SAt from a three-dimensional map with the engine speed Ne, the load factor KL, and the air-fuel ratio AF as axes. In this three-dimensional map, each relationship between the target ignition timing SAt and the engine speed Ne, the load factor KL, and the air-fuel ratio AF is stored in advance. Each graph (A) to (C) in FIG. 7 shows the relationship among the target ignition timing SAt, the engine speed Ne, the load factor KL, and the air-fuel ratio AF in the three-dimensional map. In step 124, the target ignition timing SAt corresponding to the engine speed Netdc obtained in step 122 and the load factor KL and air-fuel ratio AF obtained in step 114 is obtained from the above three-dimensional map.

  In the next step 126, the set time TM of the ignition timer that determines the actual ignition timing of the spark plug 16 is calculated. In the present embodiment, the ignition timer is started with a predetermined crank angle (for example, 30 ° BTDC or the like) as a reference time point, and ignition by the spark plug 16 is performed when the timer set time TM has elapsed. When predicting a change in engine speed Ne from θivc to TDC, a change in crank angle θ from θivc to TDC is also predicted every minute time Δt. Set the timer so that the actual ignition timing matches the target ignition timing SAt by calculating back the time from the change in the crank angle θ every minute time Δt until the crank angle reaches the target ignition timing SAt. Time TM can be set.

  In step 128, the elapsed time from the reference time is measured by the ignition timer, and it is determined whether or not the elapsed time has reached the timer set time TM set in step 126. When the elapsed time reaches the timer set time TM, ignition by the spark plug 16 is performed.

  According to the ignition timing control routine described above, on the basis of the correlation between the engine speed Ne and the torques Ti, Tfr, Tfrex acting on the crankshaft 24, θivc and later after obtaining information on the engine operating state is obtained. It is possible to accurately predict changes in the engine speed Ne. Since the target ignition timing SAt is set based on this accurate prediction of the engine speed Ne, even if the engine speed fluctuates significantly as during idling, an ideal ignition according to the engine speed is required. The target ignition timing SAt can be set as the timing.

  Furthermore, since the set time TM of the ignition timer is set based on the change of the engine speed Ne accurately predicted as described above, even when the engine speed fluctuates greatly during idling, It is possible to prevent the actual ignition timing from deviating from the target ignition timing SAt, and it is possible to always perform ignition at an ideal ignition timing corresponding to the rotational speed.

  In the above embodiment, the “information acquisition means” of the first and third inventions is realized by the execution of the process of step 114 by the ECU 50, and the execution of the processes of steps 116, 118, and 120 The “torque calculation means” of the first and third aspects of the invention is realized. Further, the “rotational speed predicting means” of the first and third aspects of the present invention is realized by the execution of the process of step 122 by the ECU 50, that is, the execution of the subroutine of FIG. Further, the “target ignition timing setting means” according to the first aspect of the present invention is realized by the execution of the processing of step 124 by the ECU 50. Further, the “timer set time calculation means” of the second and third inventions is realized by the execution of the process of step 126 by the ECU 50, and the second and third inventions are realized by the execution of the processes of steps 128 and 130. The “ignition plug driving means” is realized.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the above embodiment, the engine load factor KL is obtained from the amount of intake air detected by the air flow meter 56. However, when an intake pipe pressure sensor for detecting the pressure (intake pipe pressure) in the intake passage 30 is provided. May use the intake pipe pressure instead of the load factor KL.

  In the above embodiment, the indicated torque at each crank angle is approximated by the average indicated torque from BDC to TDC, but the change in indicated torque from BDC to TDC is determined using parameters (engine speed Ne, load factor KL, empty It may be determined for each fuel ratio and ignition timing (SA) and stored in a map, and the indicated torque may be determined for each crank angle.

  In the above embodiment, the target ignition timing SAt is set according to the engine speed Netdc at the TDC which is the virtual ignition timing. However, the average engine speed from a predetermined time (for example, 10 ° BTDC) to the TDC is set. The target ignition timing SAt may be determined according to the above. Further, the virtual ignition timing may not be TDC and may be within a crank angle range in which the target ignition timing may be actually set.

  Further, the target ignition timing SAt may be fixed to a predetermined crank angle (for example, TDC) regardless of the engine speed Ne. In this case as well, since the ignition timer setting time TM can be set based on the accurately predicted change in the engine speed Ne, it is possible to prevent the actual ignition timing from deviating from the target ignition timing SAt. The ignition can always be performed according to the target ignition timing SAt.

  In the above embodiment, the ignition timing of the spark plug 16 is controlled by the ignition timer. However, when the disassembly capability of the crank angle sensor 52 is high, the crankshaft 24 is detected from the crank angle signal of the crank angle sensor 52. The rotational position may be obtained, and the spark plug 16 may be ignited when the rotational position of the crankshaft 24 coincides with the target ignition timing SAt.

  In the above embodiment, the valve closing time θivc of the intake valve 12 is set as the information acquisition time, but a predetermined time after θivc may be set as the information acquisition time. The information acquisition time may be before the crank angle range in which the target ignition timing SAt is set (advanced side). Further, when the ignition timing is controlled by the ignition timer as in the above embodiment, it may be before the reference time of the timer set time TM.

  Furthermore, in the above embodiment, the present invention is applied to ignition timing control at idling. However, the present invention has large fluctuations in engine speed not only during idling but also during sudden acceleration / deceleration or shift change. The control of the ignition timing in the situation is widely applicable. Whether or not the fluctuation of the engine speed is large can be determined, for example, by comparing the rate of change {Ne (t + Δt) / Ne (t)} of the engine speed with a predetermined reference value. By applying the present invention to the control of the ignition timing in such a situation, it becomes possible to always perform ignition at an ideal ignition timing, and it is possible to operate the engine with high efficiency.

1 is a schematic configuration diagram of an engine system to which an ignition timing control device for an internal combustion engine as an embodiment of the present invention is applied. It is a flowchart of the ignition timing control routine executed in the embodiment of the present invention. 3 is a flowchart of a subroutine executed in an ignition timing control routine shown in FIG. 4 is a graph showing the relationship between average indicated torque Ti, engine speed Ne, load factor KL, air-fuel ratio, and ignition timing SA. 5 is a graph showing the relationship between mechanical friction Tf and engine speed Ne. It is a graph which shows each relationship between auxiliary machine load torque Tfrexivc, engine speed Ne, and auxiliary machine load factor (alpha). 4 is a graph showing each relationship between a target ignition timing SAt, an engine speed Ne, a load factor KL, and an air-fuel ratio AF.

Explanation of symbols

10 Combustion chamber 12 Intake valve 14 Exhaust valve 16 Spark plug 18 Intake port 20 Exhaust port 24 Crankshaft 30 Intake passage 36 Throttle valve 38 Injector 50 ECU
52 Crank angle sensor 54 Throttle sensor 56 Air flow meter

Claims (4)

Information acquisition means for acquiring information related to the operating state of the internal combustion engine, including the number of revolutions at the time of closing of the intake valve or at a predetermined time after closing;
Torque calculating means for calculating torque acting on the crankshaft of the internal combustion engine at the time of information acquisition based on the acquired operating state information;
A rotation speed prediction means for predicting a change in the rotation speed from the information acquisition time point to a predetermined virtual ignition timing based on the acquired operation state information and the torque calculated by the torque calculation means;
Target ignition timing setting means for setting a target ignition timing based on the number of revolutions predicted in the virtual ignition timing;
An ignition timing control device for an internal combustion engine, comprising: Timer setting time calculation means for calculating a timer setting time from a predetermined reference time point to ignition by an ignition plug from the change in the rotation speed predicted by the rotation speed prediction means and the target ignition timing;
Spark plug driving means for performing ignition by the spark plug when the timer set time has elapsed from the reference time;
The ignition timing control device for an internal combustion engine according to claim 1, further comprising: Information acquisition means for acquiring information related to the operating state of the internal combustion engine, including the number of revolutions at the time of closing of the intake valve or at a predetermined time after closing;
Torque calculating means for calculating torque acting on the crankshaft of the internal combustion engine at the time of information acquisition based on the acquired operating state information;
A rotation speed prediction means for predicting a change in the rotation speed from the information acquisition time point to a predetermined target ignition timing based on the acquired operating state information and the torque calculated by the torque calculation means;
Timer setting time calculation means for calculating a timer setting time from a predetermined reference time point to ignition by an ignition plug from the change in the rotation speed predicted by the rotation speed prediction means and the target ignition timing;
Spark plug driving means for performing ignition by the spark plug when the timer set time has elapsed from the reference time;
An ignition timing control device for an internal combustion engine, comprising: The rotational speed prediction means uses the rotational speed acquired by the information acquisition means and the torque calculated by the torque calculation means as initial values, and based on the correlation between the rotational speed and the torque acting on the crankshaft. The ignition timing control device for an internal combustion engine according to any one of claims 1 to 3, wherein a change in the rotation speed after the information acquisition time point is predicted.

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