JP3673909B2 - Internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine (hereinafter referred to as an engine) mounted on a vehicle.
[0002]
[Related background]
Conventionally, in order to reduce an acceleration shock (abrupt change in the vehicle front-rear G) caused by a driver's careless accelerator operation, control for suppressing a sudden increase in engine torque during acceleration has been performed. For example, FIG. 6 shows a case where the engine torque is adjusted by controlling the fuel injection amount based on the target average effective pressure Pe set from the engine speed, throttle opening, etc. As shown in FIG. When the accelerator is stepped on while the vehicle is decelerating and shifts to acceleration (when the idle switch is turned off), the target average effective pressure Pe that rapidly increases as indicated by the broken line together with the accelerator operation amount is normally shown by a solid line In this way, the acceleration shock is reduced gradually.
[0003]
[Problems to be solved by the invention]
However, the start timing of the tailing process described above may not be appropriate depending on the driving situation of the vehicle. That is, for example, when the vehicle decelerates, the automatic transmission is shift-controlled to the downshift side for the purpose of ensuring the engine braking action and keeping the engine speed within the fuel cut rotation range. When the downshift is started immediately before the driver depresses the accelerator, the tailing process is started before the shift is completed (the shift period T elapses).
[0004]
As is well known, since the automatic transmission during shifting does not exhibit a torque transmission action, torque transmission is suddenly performed based on the target average effective pressure Pe already increased to a certain value ΔPe by tailing at the time of completion of shifting. On the contrary, there was a case where the acceleration shock was strengthened. In order to avoid such a problem, it is conceivable to reduce the tailing gain to make the target average effective pressure Pe increase more slowly. In this case, however, the acceleration responsiveness deteriorates. Problems arise.
[0005]
An object of the present invention is to provide an internal combustion engine that can reduce acceleration shock when acceleration is started during shift of an automatic transmission while avoiding deterioration of acceleration response.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, there is provided a fuel control means for gradually increasing the amount of fuel supplied to the internal combustion engine to the required fuel amount during acceleration, and an automatic transmission when a predetermined operating state is detected. Shift control means for executing the shift control, and stop means for stopping the operation of the fuel control means until a predetermined period before the shift is completed when there is an acceleration request during the shift control by the shift control means. Therefore, for example, when the downshift control is started as the vehicle decelerates and the driver depresses the accelerator before the downshift is completed, the increase in the amount of fuel supplied to the internal combustion engine is delayed until the downshift is completed. Thus, the increase in the fuel supply amount is started at an appropriate timing synchronized with the resumption of torque transmission interrupted during the downshift. In addition, since the timing is appropriate as described above, it is not necessary to moderately increase the fuel supply amount more than necessary.
[0007]
According to a second aspect of the present invention, fuel control means for gradually increasing the amount of fuel supplied to the internal combustion engine to the required fuel amount during acceleration, and shift control of the automatic transmission is executed when a predetermined operating state is detected. Shift control means, and when there is an acceleration request during shift control by the shift control means, the stop means for stopping the operation of the fuel control means until a predetermined period before the shift is completed, and the shift is completed from the time of the acceleration request And a fuel supply means for supplying less fuel than the required fuel amount of the internal combustion engine by a predetermined period . Therefore, since the fuel supply amount is increased in advance by a predetermined period when the shift is completed, the acceleration can be started promptly when the shift is completed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in an in-cylinder injection type gasoline engine will be described.
In the overall configuration diagram of FIG. 1, reference numeral 1 denotes an engine, and a combustion chamber 2 and an intake system are designed exclusively for in-cylinder injection. The cylinder head 3 of the engine 1 is provided with an electromagnetic fuel injection valve 5 together with a spark plug 4 for each cylinder, and high-pressure fuel supplied from a fuel pump (not shown) is supplied from the fuel injection valve 5 to the combustion chamber 2. It is designed to be injected directly into the inside.
[0009]
An intake port 6 is formed in the cylinder head 3 in a substantially upright direction, and an intake passage 7 is connected to the intake port 6. The intake passage 7 is provided with a throttle valve 8 for adjusting the amount of intake air, and is opened and closed according to the driver's accelerator operation. The intake air taken in from the intake passage 7 is introduced into the combustion chamber 2 from the intake port 6 through the throttle valve 8 as the intake valve 9 is opened, and fuel is injected from the fuel injection valve 5 into the intake air. Then, it burns by ignition of the spark plug 4.
[0010]
An exhaust port 10 is formed in the cylinder head 3 in a substantially horizontal direction, and an exhaust passage 11 is connected to the exhaust port 10. The exhaust gas after combustion is discharged into the atmosphere from the combustion chamber 2 through the exhaust port 10, the exhaust passage 11, a catalyst and a silencer (not shown) as the exhaust valve 12 is opened.
On the other hand, the engine 1 is combined with a 5-speed automatic transmission 13. The automatic transmission 13 has a general configuration including a torque converter 14, a lockup clutch 15 for directly connecting the torque converter 14, and a planetary gear mechanism 16. As is well known, the operation state of the planetary gear mechanism 16 is changed. By switching according to the engagement of the friction engagement element, the rotation from the engine 1 is changed and transmitted to the drive wheel (not shown).
[0011]
In the vehicle compartment, an input / output device (not shown), a storage device (ROM, RAM, BURAM, etc.) used for storing control programs and control maps, an ECU (engine) equipped with a central processing unit (CPU), a timer counter, etc. Control unit) 21 and AT-CU (transmission control unit) 22 are installed, ECU 21 performs overall control of engine 1, and AT-CU 22 performs overall control of automatic transmission 13.
[0012]
On the input side of the ECU 21, there are a throttle sensor 23 for detecting the opening θTH of the throttle valve 8, an idle switch 24 for detecting the fully closed state of the throttle valve 8, an engine speed sensor 25 for detecting the rotational speed Ne of the engine 1, Various sensors such as an accelerator sensor 26 for detecting the accelerator pedal operation amount Acc by the driver, a vehicle speed sensor 27 for detecting the vehicle speed V, and a shift position sensor 28 for detecting the shift position of the automatic transmission 13 selected by the driver. Are connected, and their detection information is input. The ignition plug 4 described above is connected to the output side of the ECU 21 via an igniter 31 and an ignition coil 32, and a fuel injection valve 5 is connected.
[0013]
Various sensors such as the vehicle speed sensor 27 and the shift position sensor 28 are connected to the input side of the AT-CU 22, and the friction engagement element and the lockup clutch 15 of the automatic transmission 13 are connected to the output side. A hydraulic solenoid 33 for operation is connected.
The ECU 21 executes fuel injection control and ignition timing control of the engine 1 based on detection information from each sensor. With respect to the fuel injection control, the fuel injection valve 5 is driven and controlled based on the target air-fuel ratio and the fuel injection mode (representing the stroke in which fuel injection is executed). In the in-cylinder injection type engine 1 of the present embodiment, the target average effective pressure Pe representing the engine load is used as a parameter for executing the fuel injection control, and based on the throttle opening θTH and the engine speed Ne. The target average effective pressure Pe is calculated from a map (not shown), and the target air-fuel ratio, fuel injection mode, and the like are set according to another map from the target average effective pressure Pe and the engine speed Ne. The fuel injection mode is a mode peculiar to a direct injection type engine that can inject fuel not only in the intake stroke but also in the compression stroke. In a region where the target average effective pressure Pe and the engine speed Ne are relatively low, the fuel injection mode is stratified by the compression stroke injection. Super lean operation is realized by executing combustion, and in a region beyond that, normal intake stroke injection is executed to ensure torque by uniform combustion.
[0014]
As for the ignition timing control, various correction amounts are added to the basic ignition timing determined from the engine speed Ne and the volumetric efficiency EV to obtain the ignition timing, and the igniter 31 is driven to control the actual ignition timing. . The volumetric efficiency EV is obtained from the target average effective pressure Pe and the engine speed Ne.
On the other hand, in the present embodiment, the AT-CU 22 functions as a shift control unit, and executes shift control and lockup clutch control of the automatic transmission 13 based on detection information from each sensor. For example, when a travel range such as D (drive) is detected by the shift position sensor 28, the gear position is determined according to a map (not shown) from the target average effective pressure Pe, the vehicle speed V, and the like, and the hydraulic solenoid 33 performs frictional engagement. The combination element is actuated to achieve the gear position. Also, in the coupling region of the torque converter 14, when the vehicle is in a traveling state that does not require a torque increasing action, such as during constant speed traveling, the lockup clutch 15 is directly connected by the hydraulic solenoid 33 to improve fuel efficiency. Then, the AT-CU 22 outputs the shift start timing and the operating state of the lockup clutch 15 to the ECU 21, and as described later, these pieces of information are used for engine control on the ECU 21 side.
[0015]
Next, control executed by the ECU 21 when the vehicle shifts from deceleration to acceleration will be described.
When the accelerator is depressed and the vehicle shifts to acceleration while the vehicle is decelerating, the target average effective pressure Pe (hereinafter referred to as a map value Pe map) obtained from the map as described above rapidly increases as shown by a broken line in FIG. To increase. Here, in the present embodiment, when a predetermined condition is satisfied, the target average effective pressure Pe is tailored in two stages for the purpose of reducing acceleration shock and ensuring acceleration responsiveness, and the details thereof will be described below. .
[0016]
The ECU 21 executes the acceleration tailing routine shown in FIG. 2 at a predetermined control interval, and first determines whether or not a tailing start condition preset in step S2 is satisfied. In the present embodiment, the following two requirements are defined as the start condition, and it is determined that the start condition is satisfied when both of these requirements are satisfied.
[0017]
1) The vehicle speed V is equal to or higher than the predetermined value V01. 2) Since the idle switch is switched from on to off, that is, the start time (vehicle speed V≈0) is excluded due to the vehicle speed requirement of 1). The start condition is satisfied when the driver depresses the accelerator during deceleration. Except for when starting, the shock when shifting from deceleration to acceleration changes the slip amount of the torque converter 14 that was a negative value during deceleration to a positive value as described later. Because of the delay until transmission is started, or when the automatic transmission 13 is downshifting at the start of acceleration, the delay until the transmission is completed and the power transmission is restarted is the cause. This is because the tailing process is not necessary in a situation where the slip amount is not a negative value and the downshift is not executed.
[0018]
When the determination in step S2 is NO (No), the routine ends. Therefore, in this case, in the fuel injection control executed in a separate routine, the map value Pe map is applied as the target average effective pressure Pe as usual, and the engine torque is controlled according to the accelerator operation without performing tailing. Is done.
Further, when the determination in step S2 is YES (positive), the process proceeds to step S4 to set each parameter applied to the tailing process. This setting process is based on the shift stage (1st to 5th speed) of the automatic transmission 13 immediately before the start condition is satisfied, the operating state of the lockup clutch 15 (directly connected or not directly connected), and the predetermined value Ne0. Is performed according to the level of the engine speed Ne (Ne ≧ Ne0 or Ne <Ne0), and as shown in the explanatory diagram of FIG. 3, in the primary tailing gain G1, the secondary tailing gain G2, and the primary tailing The hold value Pe hold for limiting the upper limit of the target average effective pressure Pe, and the secondary tailing start time Tstart (starting when the start condition is satisfied) are set as parameters.
[0019]
In step S4, a secondary tailing end time Tend (starting from when the start condition is satisfied) and a downshift predicted required time Tshift (starting from the start of shifting to the downshift side) are set. . The end time Tend is the automatic transmission immediately before the start condition is satisfied so that the secondary tailing ends when the target average effective pressure Pe increasing by tailing reaches the map value Pe map as described later. It is set according to 13 shift speeds (1st to 5th) and whether or not the fuel cut caused by the deceleration is restored at that time. Further, since the estimated required time Tshift from the start to the completion of the shift to the downshift side varies depending on the shift stage, for example, every shift stage such as the third speed to the first speed or the second speed to the first speed. Is set.
[0020]
When the setting process in step S4 is completed, primary tailing of the target average effective pressure Pe is executed in subsequent steps S6 to S10. First, in step S6, a tailing value Petail1 is calculated based on the primary tailing gain G1 according to the following equation (1).
Pe tail1 = Pe (n-1) + G1 (1)
Here, Pe (n-1) is the target average effective pressure Pe one cycle before applied to the fuel injection control. Next, in step S8, the minimum value is selected from the hold value Pe hold, tailing value Pe tail1, and map value Pe map described above, and that value is set as the final target average effective pressure Pe. Thereafter, in step S10, it is determined whether or not the secondary tailing start time Tstart has elapsed. If it has not yet elapsed, the process returns to step S6. Therefore, until the secondary tailing start time Tstart elapses, the processes of step S6 and step S8 are repeated, and the target average effective pressure Pe selected as the minimum value is applied to the fuel injection control.
[0021]
Here, the map value Pe map and the tailing value Pe tail1 increase together with the target average effective pressure Pe (= map value Pe map) immediately before the accelerator depression, but the map value Pe map is used for accelerator operation. The tailing value Pe tail1 increases according to the first-order tailing gain G1, while increasing depending on it. Then, since the smaller side of the map value Pe map and the tailing value Pe tail1 is selected as the target average effective pressure Pe, the target average effective pressure Pe increases while being restricted with the primary tailing gain G1 as the upper limit, and then When the target average effective pressure Pe reaches the hold value Pe hold, the target average effective pressure Pe is kept at that value. Since a relatively large value is set as the primary tailing gain G1, the target average effective pressure Pe increases considerably abruptly even when the restriction is imposed. In addition, the target average effective pressure Pe may be increased to the hold value Pe hold according to the map value Pe map without providing the restriction by the primary tailing gain G1.
[0022]
When the secondary tailing start time Tstart elapses and the determination in step S10 is YES, it is determined in step S12 whether or not the estimated required time Tshift has elapsed since the start of the downshift. This process is performed based on the shift start timing input from the AT-CU 22, and when information on the shift start timing is input along with the downshift at the time of deceleration, the ECU 22 requires the prediction required corresponding to the downshift gear stage. The time Tshift is selected, and the estimated required time Tshift is measured starting from the shift start timing. When the estimated required time Tshift has not elapsed, the process returns to step S6, and the processes from step S6 to step S10 are repeated.
[0023]
When the estimated required time Tshift has elapsed, the routine proceeds to step S14, where the tailing value Petail2 is calculated based on the secondary tailing gain G2 according to the following equation (2). The smaller side of the map value Pe map obtained from the operation state at the time is selected, and that value is set as the final target average effective pressure Pe.
[0024]
Pe tail2 = Pe (n-1) + G2 (2)
Thereafter, it is determined in step S18 whether a preset tailing termination condition is satisfied. In the present embodiment, the following five requirements are defined as termination conditions, and it is determined that the termination condition is satisfied when any of the requirements is satisfied.
3) End time Tend has elapsed since the start of control 4) The idle switch has been switched on again 5) Vehicle speed V has become less than the predetermined value V02 (hysteresis setting) 6) Shift position switched to N range 7) The requirement that the map value Pe map is equal to or greater than the predetermined value Pe0 continues for the predetermined time T0 is that the secondary tailing has been completed to the end by the lapse of the end time Tend (target average during tailing) This means that the effective pressure Pe has reached the map value Pe map). In addition, each requirement after 4) means that it is no longer necessary to continue the secondary tailing due to a change in the operating state. For example, in the requirement 4), the map value Pe map rapidly decreases due to the suspension of the accelerator operation. As a result, the secondary tailing is interrupted because it falls below the target average effective pressure Pe during tailing.
[0025]
Until the tailing end condition is satisfied in step S18, the processing of step S14 and step S16 is repeated, and when the end condition is satisfied, the routine is ended. Thus, as in the case of the primary tailing described above, the smaller side of the map value Pe map and the target tailing value Pe tail2 is selected as the target average effective pressure Pe, so even if the accelerator depression speed is abrupt, The target average effective pressure Pe is restricted from increasing rapidly with the secondary tailing gain as an upper limit. Here, since the secondary tailing gain is set to a smaller value than the primary tailing gain (G2 <G1), the increase in the target average effective pressure Pe during tailing becomes moderate.
[0026]
And in this embodiment, ECU21 when performing the process of the above step S14 and step S16 functions as a fuel control means, and ECU21 when performing the process of step S12 functions as a stop means. Moreover, ECU21 when performing the process of step S6 and step S8 functions as a fuel supply means.
[0027]
Next, the control state of the target average effective pressure Pe by the above-described processing of the ECU 21 will be described according to the time charts of FIGS. Here, the time chart of FIG. 4 shows a case where the secondary tailing starts immediately after the secondary tailing start time Tstart elapses, and the time chart of FIG. 5 shows that the secondary tailing start time Tstart elapses, Furthermore, the case where the start of the secondary tailing is delayed until the estimated required time Tshift elapses is shown.
[0028]
First, the case of FIG. 4 will be described. When the driver depresses the accelerator while the vehicle is decelerating, the idle switch 24 is turned off, the start condition is established (step S2), and the tailing process is started. In this example, the lockup clutch 15 is not directly connected immediately before the start condition is satisfied, the engine speed Ne is lower than the predetermined value Ne0, and the gear position is 2nd. Therefore, each parameter corresponding to these conditions is It is set (step S4).
[0029]
In this example, since the accelerator is stepped on more rapidly than the speed corresponding to the primary tailing gain G1, the target average effective pressure Pe is 1 slightly less than the map value Pe map indicated by the broken line. After increasing according to the next tailing gain G1, the hold value Pe hold is maintained. Since the primary tailing gain G1 is set as a relatively large value as described above, the target average effective pressure Pe increases considerably abruptly even when the restriction is imposed, and accordingly the engine speed Ne. Rises quickly. As a result, the slip amount of the torque converter 14 that was a negative value (non-driving state) at the time of deceleration is quickly changed to a positive value (driving state).
[0030]
The secondary tailing start time Tstart is set in the process of step S4 so as to coincide with the timing at which the slip amount turns to a positive value. Accordingly, when the slip amount turns to a positive value, the secondary tailing start time Tstart elapses almost simultaneously (step S10), and the target average effective pressure Pe increases according to the secondary tailing gain G2. Since the secondary tailing gain G2 is set to a smaller value than the primary tailing gain G1, the increase in the target average effective pressure Pe is moderate. Thereafter, in this example, it is assumed that the end time Tend has elapsed, the end condition is established based on the requirement 3) above (step S18), the secondary tailing is ended, and the control shifts to the normal map value Pe map. As described above, since the end time Tend is set to end when the target average effective pressure Pe during tailing reaches the map value Pe map, the control is performed from the secondary tailing to the control based on the map value Pe map. The step of the target average effective pressure Pe at the time of transition (that is, the step of the engine torque) is extremely small and does not cause an acceleration shock.
[0031]
On the other hand, the case of FIG. 5 will be described. In this example, the downshift from the 3rd speed to the 1st speed is started immediately before the start condition is satisfied, and even when the secondary tailing start time Tstart has elapsed, the prediction is still required. The case where time Tshift has not passed is shown. As described above, the estimated required time Tshift is a required time from the start to the completion of the shift, and thus means that the planetary gear mechanism 16 is shifting until the estimated required time Tshift elapses. At this time, even after the elapse of the secondary tailing start time Tstart (step S10), the target average effective pressure Pe continues to be held at the hold value Pe hold, that is, when the estimated required time Tshift has elapsed, that is, the shift is completed and the drive side When the torque transmission to is resumed, the secondary tailing is started (step S12), and the target average effective pressure Pe is increased according to the secondary tailing gain G2.
[0032]
As described above, in the internal combustion engine of the present embodiment, the start of the secondary tailing is delayed until it is estimated that the downshift is completed as the predicted required time Tshift elapses. Therefore, since the secondary tailing is started at an appropriate timing synchronized with the resumption of torque transmission that was interrupted during the shift, the acceleration can be started without generating a shock.
[0033]
Moreover, since the start timing of the secondary tailing is appropriate as described above, the acceleration shock is suppressed even if the secondary tailing gain G2 is somewhat large, and the acceleration response when the tailing gain is reduced more than necessary as in the conventional example. Sexual deterioration can be avoided in advance. In addition, since the fuel injection amount together with the target average effective pressure Pe is controlled in advance by the primary tailing until the estimated required time Tshift elapses after the accelerator is depressed, secondary tailing is started. Thus, acceleration can be started immediately, and the above-described deterioration in acceleration response can be avoided more reliably. As described above, the reduction in acceleration shock and the securing of acceleration responsiveness can be achieved at a very high level, thereby improving the commercial value of the vehicle.
[0034]
This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above-described embodiment, the present invention is embodied as the in-cylinder injection type gasoline engine 1, but may be embodied as a normal intake pipe injection type gasoline engine or a diesel engine.
In the above embodiment, the target average effective pressure Pe is subjected to the primary tailing before the estimated required time Tshift elapses. However, the primary tailing is not necessarily performed. Even in this case, since the start timing of the secondary tailing is appropriate as described above, it is not necessary to reduce the gain G2 more than necessary, and deterioration of acceleration response can be avoided.
[0035]
Furthermore, in the above-described embodiment, the completion of downshift is estimated based on the preset required time Tshift. This is because only the shift start timing information is input from the AT-CU 22 to the ECU 21 side, but when the shift completion timing information is also input, the secondary tailing is started in synchronization with the timing. May be.
[0036]
On the other hand, in the above embodiment, assuming that acceleration is started during the shift to the downshift, the start of the secondary tailing is delayed until the shift is completed. However, the shift direction is not limited to this, and the shift to the upshift is performed. Assuming that acceleration is started during the gear shift, a process of delaying the start of the secondary tailing until the gear shift is completed may be performed.
[0037]
【The invention's effect】
As described above, according to the internal combustion engine of the present invention, it is possible to reduce acceleration shock when acceleration is started during shifting of the automatic transmission while avoiding deterioration of acceleration response.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an in-cylinder injection type gasoline engine of an embodiment.
FIG. 2 is a flowchart showing an acceleration tailing routine executed by an ECU.
FIG. 3 is an explanatory diagram showing a setting state of each parameter applied to tailing processing.
FIG. 4 is a time chart when secondary tailing is started at a timing when the slip amount turns positive.
FIG. 5 is a time chart when the secondary tailing is started at the timing when the downshift is completed.
FIG. 6 is a time chart showing a tailing process of a conventional example.
[Explanation of symbols]
1 engine (internal combustion engine)
21 ECU (fuel control means, stop means, fuel supply means)
22 AT-CU (shift control means)

Claims (2)

Fuel control means for gradually increasing the amount of fuel supplied to the internal combustion engine during acceleration to the required fuel amount;
Shift control means for executing shift control of the automatic transmission when a predetermined driving state is detected;
When there is an acceleration request during down-shift control by the shift control means, the internal combustion engine, characterized in that a stop means for stopping the operation of said fuel control means to a predetermined period before the downshift is completed. Fuel control means for gradually increasing the amount of fuel supplied to the internal combustion engine during acceleration to the required fuel amount;
Shift control means for executing shift control of the automatic transmission when a predetermined driving state is detected;
Stop means for stopping the operation of the fuel control means until a predetermined period before the shift is completed when an acceleration request is made during shift control by the shift control means
Fuel supply means for supplying less fuel than the required fuel amount of the internal combustion engine from the time of the acceleration request to a predetermined period in which the shift is completed;
An internal combustion engine comprising:

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