JP2011017255A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of achieving favorable drivability suitable to a plurality of operation conditions in the case that the supply of fuel is stopped when engine speed reaches an upper limit.SOLUTION: The control device 1 of the engine 3 performs fuel cut when engine speed NE reaches F/C engine speed NEFC, and restarts the supply of the fuel when the engine speed NE is lower than recovery engine speed NERTN. When a shifting mode is an S mode, the torque of the engine 3 is controlled so that the engine speed NE is target engine speed NELMTCM after the supply of fuel is restarted after performing the fuel cut (steps 34-37, 83). When the shifting mode is an N mode, the torque of the engine 3 is limited before the engine speed NE reaches the F/C engine speed NEFC, and the engine speed NE is controlled to be the target engine speed NELMTCM (steps 38-41, 83).

Description

  The present invention relates to a control device for an internal combustion engine in which fuel supply is stopped when the rotational speed of the internal combustion engine reaches a predetermined upper limit rotational speed.

  As a control device for a conventional internal combustion engine, for example, one disclosed in Patent Document 1 is known. In this control device, when the rotational speed of the internal combustion engine mounted on the vehicle (hereinafter referred to as “engine rotational speed”) reaches a predetermined upper limit rotational speed, the throttle valve opening degree is independent of the accelerator pedal opening degree. Is set to a predetermined small opening, and the engine speed is limited by stopping the fuel supply to the internal combustion engine (fuel cut).

Japanese Patent No. 4100032

  As described above, in this conventional control device for an internal combustion engine, when the engine speed reaches the upper limit speed, the throttle valve is always set to a small opening and fuel cut is executed. For this reason, when the upper limit rotational speed is reached, the output of the internal combustion engine (hereinafter referred to as “engine output”) and the engine rotational speed rapidly decrease due to fuel cut, resulting in a deterioration in drivability. In order to avoid such a situation, when control is performed to limit the engine output before the engine speed reaches the upper limit speed, the drivability desired by the driver may be obtained depending on the driving conditions. It may not be obtained. For example, in driving conditions such as sports mode where driving performance is important, the maximum output is more important than the smooth change in engine output and engine speed. If this happens, the driver's request cannot be met.

  The present invention has been made to solve the above-described problems, and is suitable for each of a plurality of operating conditions when fuel supply is stopped when the engine speed reaches the upper limit speed. Another object of the present invention is to provide a control device for an internal combustion engine that can achieve high drivability.

  In order to achieve the above object, the invention according to claim 1 of the present application is such that the engine speed (the engine speed NE in the embodiment (hereinafter the same in this section)) that is the speed of the internal combustion engine 3 is the upper limit speed. Internal fuel that stops supplying fuel when (fuel cut speed NEFC) is reached, and then resumes fuel supply when the engine speed falls below a predetermined return speed NERTN that is smaller than the upper limit speed The engine control device 1 is an engine speed detecting means (crank angle sensor 22) for detecting the engine speed, and after the fuel supply is resumed after the engine speed reaches the upper limit speed, the engine speed First rotation speed control means (ECU 2, steps 34 to 37 in FIG. 4) for controlling the output of the internal combustion engine 3 so that the number of rotations becomes a first target rotation speed (target rotation speed NELMTCM) smaller than the upper limit rotation speed. 7) and after the detected engine speed exceeds a predetermined engine speed (NE limit start engine speed NELMTH) smaller than the upper engine speed, the engine engine speed is between the upper engine speed and the predetermined engine speed. Second rotational speed control means (ECU 2, steps 38 to 41 in FIG. 4, step 83 in FIG. 7) for controlling the output of the internal combustion engine 3 so as to be the second target rotational speed (target rotational speed NELMTCM), Selecting means (ECU 2, steps 31 to 33 in FIG. 4) for selecting one of the first rotational speed control means and the second rotational speed control means in accordance with the operating condition (transmission mode) of the internal combustion engine 3; It is characterized by.

  According to the control device for an internal combustion engine, when the engine speed reaches the upper limit speed, the fuel supply is stopped, and when the engine speed falls below a predetermined return speed that is smaller than the upper limit speed. Restart the fuel supply. According to this configuration, since the fuel supply is stopped when the engine speed reaches the upper limit speed, the fuel is not burned and the engine speed is reduced. Thereby, the overrev of the internal combustion engine is avoided and the internal combustion engine is protected. Further, the fuel supply is resumed when the engine speed falls below a predetermined return speed smaller than the upper limit speed.

  The control device also includes first and second rotation speed control means as engine rotation speed control means, and selects one of them according to the operating condition of the internal combustion engine. The first rotational speed control means is configured to cause the internal combustion engine to have a first target rotational speed that is smaller than the upper limit rotational speed after the fuel supply is resumed after the engine rotational speed reaches the upper limit rotational speed. Control the output of. As described above, the output of the internal combustion engine is not limited until the engine speed reaches the upper limit engine speed, so that the maximum output of the internal combustion engine can be obtained. Accordingly, drivability suitable for driving conditions such as sports mode where driving performance is important can be obtained. Further, the output of the internal combustion engine is controlled so that the engine speed becomes the first target speed smaller than the upper limit speed after the fuel supply is resumed after the engine speed reaches the upper limit speed. Thereafter, the overrev of the internal combustion engine can be prevented.

  On the other hand, after the engine speed exceeds a predetermined speed smaller than the upper limit speed, the second speed control means sets the engine speed to a second target speed between the upper limit speed and the predetermined speed. Thus, the output of the internal combustion engine is controlled. Thus, since the output of the internal combustion engine is limited before the engine speed reaches the upper limit speed and the engine speed is controlled to the second target speed, the fuel when the engine speed reaches the upper limit speed is controlled. It is possible to avoid fluctuations in the output of the internal combustion engine due to supply stop and restart. As a result, the output and the rotational speed of the internal combustion engine change smoothly, and as a result, drivability suitable for it can be obtained under operating conditions where smoothness is important.

  As described above, according to the present invention, drivability suitable for each of a plurality of operating conditions is obtained by selecting one of the first and second rotational speed control means according to the operating conditions of the internal combustion engine. be able to.

  According to a second aspect of the present invention, in the control device 1 for an internal combustion engine according to the first aspect, the predetermined rotational speed is set to a smaller value as the increase speed of the engine rotational speed (an increase amount NE of the engine rotational speed NE) is larger. It is further characterized by further comprising a predetermined rotational speed setting means (ECU 2, step 38 in FIG. 4).

  As described above, the predetermined rotational speed is the engine rotational speed at which the second rotational speed control means starts control for limiting the engine rotational speed to the second target rotational speed lower than the upper limit rotational speed. According to the present invention, as the increasing speed of the engine speed increases, the predetermined speed is set to a smaller value, so that the control for limiting the engine speed to the second target speed starts from a lower engine speed. Is done. Therefore, even when the increase speed of the engine speed is large, the engine speed does not greatly overshoot the second target speed, so that the convergence to the second target speed can be improved and the engine speed is increased. It is possible to avoid the number from reaching the upper limit rotational speed, and thereby, smooth drivability can be more reliably realized when the second rotational speed control means is selected.

  According to a third aspect of the present invention, in the internal combustion engine control apparatus 1 according to the first or second aspect of the invention, the second rotational speed control means is an internal combustion engine 3 for controlling the engine rotational speed to the second target rotational speed. A feedforward term calculation means (ECU2, steps 4 and 15 in FIG. 3) for calculating a feedforward term (current torque TRQNELMFF) of the target output (NE limit control torque TRQNELMT), a second target rotational speed and an engine rotational speed According to the deviation (NE deviation DNELCMM), it has feedback term calculation means (ECU2, steps 12 to 14 in FIG. 3) for calculating a feedback term (P term TRQNELMP, I term TRQNELMI) of the target output, After the engine speed exceeds the predetermined speed, until a predetermined time TMDLYNELM elapses (step 9: N in FIG. 3) ), Using the feedforward term (ECU2, steps 10 and 16 in FIG. 3), and after a predetermined time TMDLYNELM has elapsed (step 9: YES in FIG. 3), using the feedforward term and the feedback term. (ECU 2, steps 11 and 16 in FIG. 3).

  According to this configuration, the target output of the internal combustion engine for controlling the engine speed to the second target speed is calculated using the feedforward term and the feedback term. Immediately after starting the control to the second target speed as the engine speed exceeds the predetermined speed, the deviation between the second target speed and the engine speed is still large. If the target output is calculated using the feedback term calculated according to the deviation, the output of the internal combustion engine fluctuates abruptly, resulting in deterioration of the convergence of the engine speed to the second target speed. According to the present invention, the target output is calculated using the feedforward term until the predetermined time elapses after the engine speed exceeds the predetermined speed, and after the predetermined time has elapsed, the feedforward term and Since the calculation is performed using the feedback term, the engine speed can be accurately controlled with high responsiveness and convergence to the second target speed while avoiding sudden fluctuations in the output of the internal combustion engine. When the number control means is selected, smooth drivability can be realized even better.

  According to a fourth aspect of the present invention, in the internal combustion engine control apparatus 1 according to the first aspect, the first rotational speed control means controls the target output of the internal combustion engine 3 for controlling the engine rotational speed to the first target rotational speed. According to the feedforward term calculation means (ECU 2, steps 94 and 107 in FIG. 9) for calculating the feedforward term and the deviation between the first target speed and the engine speed (NE deviation DNELCMM). It has feedback term calculation means (ECU2, steps 104 to 106 in FIG. 9) for calculating the terms (P term TRQNELMP, I term TRQNELMI) and supplies the target output after the engine speed reaches the upper limit speed. Until the predetermined time TMDLYNELM has elapsed (step 99 in FIG. 9: NO), calculation is performed using the feedforward term (FIG. 9). Step 102, 108 in FIG. 10) After a predetermined time TMDLYNELM has elapsed (step 99 in FIG. 9: YES), calculation is performed using the feedforward term and the feedback term (step 103 in FIG. 9, 108 in FIG. 10). It is characterized by.

  According to this configuration, the target output of the internal combustion engine for controlling the engine speed to the first target speed is calculated using the feedforward term and the feedback term. Immediately after the fuel supply is resumed after the fuel cut, the deviation between the first target engine speed and the engine speed is still large. In this state, the target output is calculated using the feedback term calculated according to this deviation. When calculated, the output of the internal combustion engine fluctuates abruptly, resulting in deterioration of the convergence of the engine speed to the first target speed. According to the present invention, the target output is calculated using the feedforward term until a predetermined time elapses after the fuel supply is resumed after the engine speed reaches the upper limit engine speed. Since the calculation is performed using the feedforward term and the feedback term after the passage of time, it is possible to avoid the start of feedback control during the fuel cut, and to avoid the sudden fluctuation in the output of the internal combustion engine and to reduce the engine speed. The first target rotational speed can be controlled with high responsiveness and convergence.

It is a figure which shows roughly the control apparatus by embodiment of this invention with the internal combustion engine to which this is applied. It is a figure which shows a shift up switch and a shift down switch. It is a flowchart which shows the calculation process of NE limit control torque. It is a flowchart which shows the execution determination process of NE limit control. It is a flowchart which shows the calculation process of a feedforward term. It is a flowchart which shows the calculation process of the present torque. It is a flowchart which shows the calculation process of the final target torque. It is a timing chart which shows the operation example obtained by NE limit control processing for every shift mode. It is a flowchart which shows the calculation process of NE limit control torque by a modification. 10 is a flowchart showing the remaining part of the NE limit control torque calculation processing of FIG. 9.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a control device 1 for an internal combustion engine of the present invention. As shown in the figure, the control device 1 includes an ECU 2, which performs various control processes of an internal combustion engine (hereinafter referred to as “engine”) 3 as will be described later.

  The engine 3 is a gasoline engine having a plurality of cylinders (not shown) mounted on a vehicle (not shown). A fuel injection valve (hereinafter referred to as “injector”) 4 is attached to an intake manifold (both not shown) of the intake pipe of the engine 3, and fuel is injected from the injector 4 into the intake pipe. The opening / closing of the injector 4 is controlled by a control signal from the ECU 2, whereby the fuel injection timing corresponding to the valve opening timing and the fuel injection amount QINJ corresponding to the valve opening time are controlled.

  An input shaft (not shown) of the automatic transmission 6 is connected to a crankshaft (not shown) of the engine 3. The automatic transmission 6 is a gear-type stepped transmission having six forward speeds and one reverse speed. The shift stage of the automatic transmission 6 is detected by a shift stage sensor 24, and the detection signal is output to the ECU 2. Based on this detection signal, the ECU 2 assigns 1 to 6 shift speed values NGR to the 1st to 6th shift speeds.

  A shift lever (not shown) is shifted to one of six shift positions “P”, “R”, “N”, “D”, “S (sports)”, and “L”. The shift position is detected by the shift position sensor 25, and the detection signal is output to the ECU 2.

  The shift mode of the automatic transmission 6 is set to the normal mode (hereinafter referred to as “N mode”) when the shift position is “D”, and the sports mode (hereinafter referred to as “S mode” when the shift position is “S”. ”). In the S mode, the automatic transmission 6 is set to a higher gear ratio than in the N mode.

  As shown in FIG. 2, the steering wheel H is provided with a shift up switch (SW) 31 and a shift down switch (SW) 32, which are arranged on the left and right of the steering wheel H, respectively.

  Depending on the operation state of the shift up switch 31 and the shift down switch 32, the shift mode of the automatic transmission 6 is an automatic shift mode (hereinafter referred to as "AT mode") that automatically sets the shift stage according to the driving state of the vehicle. And a manual shift mode (hereinafter referred to as “MT mode”) in which the gear position is set according to the driver's intention to shift.

  On the other hand, the crankshaft is provided with a crank angle sensor 22 composed of a magnet rotor and an MRE pickup (both not shown). The crank angle sensor 22 outputs a CRK signal and a TDC signal that are pulse signals as the crankshaft rotates.

  The CRK signal is output every predetermined crank angle (for example, 30 °). The ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston (not shown) of the engine 3 is in a predetermined crank angle position near the TDC (top dead center) at the start of the intake stroke in any cylinder.

  The intake pipe of the engine 3 is provided with a throttle valve (not shown) upstream of the injector 4, and an actuator 5 is connected to the throttle valve. The opening degree of the throttle valve is controlled by controlling the actuator 5 by the ECU 2, thereby controlling the amount of intake air taken into the engine 3.

  Further, the ECU 2 receives from the vehicle speed sensor 21 a detection signal indicating the vehicle speed VP, which is the vehicle speed, from the accelerator opening sensor 23 to an opening of an accelerator pedal (not shown) operated by the driver (hereinafter, “ Detection signals indicating AP) (referred to as “accelerator opening”) are respectively output.

  The ECU 2 includes a microcomputer (not shown) including a CPU, a RAM, a ROM, an input / output interface (all not shown), and the like. The detection signals of the above-described sensors 21 to 25 are respectively input to the ECU 2, A / D converted and shaped by the input interface, and then input to the CPU. In accordance with these input signals, the CPU determines the operating state of the engine 3 according to a control program stored in the ROM, etc., and executes control of the engine 3 including fuel injection control according to the determined operating state. .

  In this fuel injection control, in order to protect the engine 3 when the engine speed NE is equal to or higher than a predetermined fuel cut speed (hereinafter referred to as “F / C speed”) NEFC (for example, 7000 rpm), A fuel cut for stopping fuel injection is executed, and thereafter, when the engine speed NE falls below a return speed NERTN (for example, 6500 rpm), the fuel cut is terminated and the supply of fuel from the injector 4 is resumed. Further, NE limit control for controlling the engine speed NE to the target speed NELMTCM is executed in the vicinity of the F / C speed.

  In the present embodiment, the ECU 2 corresponds to first rotation speed control means, second rotation speed control means, selection means, predetermined rotation speed setting means, feedforward term calculation means, and feedback term calculation means.

  Next, the above-described limit control process for the engine speed NE will be described with reference to FIGS. This process is executed every predetermined time.

  FIG. 3 shows a calculation process of the NE limit control torque TRQNELMT according to the present invention. This NE limit control torque TRQNELMT is a torque for controlling the engine speed NE to the target speed NELMTCM. In this process, first, in step 1 (illustrated as “S1”, the same applies hereinafter), NE limit control execution determination processing is performed.

  FIG. 4 shows an execution determination process for this NE limit control. This process determines whether or not to perform NE limit control and sets various threshold values for the engine speed NE used for NE limit control. In this process, first, in step 31, it is determined whether or not the speed change mode is the AT mode. If this answer is NO and the shift mode is the MT mode, the routine proceeds to step 32.

  On the other hand, if the answer to step 31 is YES and the shift mode is the AT mode, it is determined in step 33 whether or not the shift stage value NGR is 6. If the answer to this question is YES and the gear position of the automatic transmission 6 is set to the maximum 6-speed, the routine also proceeds to step 32.

  In step 32, it is determined whether or not the speed change mode is the S mode. If the answer is YES and the speed change mode is the S mode, various threshold values of the engine speed NE for the S mode are set in steps 34 to 37 (see FIG. 8A). First, at step 34, an NE increase correction value DNELMTTTT described later is set to zero.

  Next, in step 35, a target rotational speed NELMTCM (= NEFC-NEREF1) in NE limit control is calculated by subtracting a first predetermined value NEREF1 (for example, 200 rpm) from the F / C rotational speed NEFC. The first predetermined value NEREF1 corresponds to a margin from the target rotational speed NELMTCM to the F / C rotational speed NEFC.

  Next, at step 36, the NE limit start rotational speed NELMTH is set to the F / C rotational speed NEFC. That is, when the speed change mode is the S mode, the NE limit start rotational speed NELMTH is equal to the F / C rotational speed NEFC and is larger than the target rotational speed NELMCM.

  Next, in step 37, the NE limit start rotational speed NELMTL (= NELMTH−DNELMHYSS) for the S mode is calculated by subtracting the hysteresis constant DNELMHYSS (for example, 700 rpm) for the S mode from the NE limit start rotational speed NELMTH. Then, the process proceeds to step 42 described later. This hysteresis constant DNELMHYSS is set so that the NE limit end rotational speed NELMTL for the S mode is smaller than the return rotational speed NERTN and the target rotational speed NELMCM.

On the other hand, if the answer to step 32 is NO and the speed change mode is the N mode, various threshold values for the engine speed NE for the N mode are set in steps 38 to 41 (see FIG. 8B). . First, at step 38, the NE increase correction value DNELMTSTT is calculated by the following equation (1) using the current value NE (n) and the previous value NE (n-1) of the engine speed NE.
DNELMTTTT = {NE (n) −NE (n−1)} · KDNEGAIN (1)
Here, {NE (n) −NE (n−1)} represents an increase amount ΔNE of the engine speed NE, and KDNEGAIN is a predetermined correction gain. As described above, the NE increase correction value DNELMTTTT is set to a larger value as the increase amount ΔNE of the engine speed NE is larger. The NE increase correction value DNELMTSTT is set to a value of 0 when the increase amount ΔNE is 0 or less and the engine speed NE is not increasing.

  Next, in step 39, as in step 35, the target rotational speed NELMTCM (= NEFC-NEREF1) is calculated by subtracting the first predetermined value NEREF1 from the F / C rotational speed NEFC.

Next, at step 40, the NE limit start rotational speed NELMTH is calculated by the following equation (2) using the F / C rotational speed NEFC, the second predetermined value NEREF2, and the calculated NE increase correction value DNELMTTTT.
NELMTH = NEFC-NEREF2-DNELMTSTT (2)

  The second predetermined value NEREF2 is larger than the first predetermined value NEREF1 (for example, 400 rpm), and the NE increase correction value DNELMTTTT ≧ 0. Therefore, when the speed change mode is the N mode, NE limit start rotational speed NELMTH is set to a value smaller than target rotational speed NELMCM. Further, as described above, the NE increase correction value DNELMTSTT is set to a larger value as the increase amount ΔNE of the engine speed NE is larger. Therefore, the NE limit start rotation speed NELMTH is increased by the engine speed NE. A larger value ΔNE is set to a smaller value.

  Next, in step 41, an N-mode NE limit end rotational speed NELMTL (= NELMTH-DNELMHYSN) is calculated by subtracting an N-mode hysteresis constant DNELMHYSN (for example, 300 rpm) from the NE limit start rotational speed NELMTH. , Go to step 42.

  In step 42 following step 37 or 41, it is determined whether or not the NE limit flag F_NELMTA is “1”. If the answer is NO and the NE limit control is not being executed, the NE limit determination value NELMT is set to the NE limit start rotational speed NELMTH (step 43). On the other hand, if the answer to step 42 is YES and the NE limit control is being executed, the NE limit determination value NELMT is set to the NE limit end rotation speed NELMTL (step 44).

  Next, in step 45, it is determined whether or not the engine speed NE is greater than or equal to the NE limit determination value NELMT. If the answer is YES and NE ≧ NELMT, the NE limit control should be started, the NE limit flag F_NELMTA is set to “1” (step 46), and this process is terminated.

  On the other hand, if the answer to step 45 is NO and NE <NELMT, the NE limit control should be terminated, the NE limit flag F_NELMTA is set to “0” (step 51), and the present process is terminated.

  Further, as described above, the hysteresis by the hysteresis constant DNELMHYS is set between the NE limit start rotational speed NELMTH and the NE limit end rotational speed NELMTL. Therefore, when the engine speed NE is between these engine speeds, the NE limit control execution / non-execution state up to that time is maintained, thereby preventing control hunting.

  On the other hand, when the answer to step 33 is NO, that is, when the speed change mode is the AT mode and the gear position of the automatic transmission 6 is not the highest speed, the NE limit control is not executed. This is because in this situation, as the engine speed NE increases, the gear position of the automatic transmission 6 shifts up and the engine speed NE does not reach the F / C speed NEFC. .

  Therefore, when the answer to step 33 is NO, the NE increase correction value DNELMTTTT is set to 0 (step 47), and in steps 48 to 50, the target rotational speed NELMTCM, the NE limit start rotational speed NELMTH, and the NE limit end rotational speed are set. The number NELMTL is set to a very large predetermined value NELRG, respectively. In step 51, the NE limit flag F_NELMTA is set to “0”, and this process is terminated.

  Returning to FIG. 3, in step 2 following step 1, it is determined whether or not the NE limit flag F_NELMTA is “1”. If the answer is NO and the NE limit control is not executed, the I term TRQNELMI of the feedback term (hereinafter referred to as “F / B term”) of the NE limit control torque TRQNELMT is reset to 0 (step 3).

  Next, in step 4, a feedforward term (hereinafter referred to as “F / F term”) of the NE limit control torque TRQNELMT is calculated.

  FIG. 5 shows the calculation process. In this process, first, in step 61, it is determined whether or not the shift position flag F_ATNPAC is “1”. This shift position flag F_ATNPAC is set to “1” when the shift position is “N” or “P”.

  If the answer is YES and the torque of the engine 3 is not transmitted from the automatic transmission 6 to the wheel side, the target torque TRQNELMFT is set to 0 (step 62), and the torque gradually decreasing amount DTRQNELMFF is set to a predetermined value DTRQNELFF ( After step 63), the process proceeds to step 68 described later.

  On the other hand, when the answer to step 61 is NO and the shift position is other than “N” and “P”, a predetermined table (not shown) is searched according to the detected vehicle speed VP to obtain the target torque. A basic value TRQNELVP is calculated (step 64). In this table, the basic value TRQNELVP is set to a larger value as the vehicle speed VP is higher.

  Next, at step 65, a gear ratio correction coefficient KGRNELM is calculated by searching a predetermined table (not shown) according to the gear position value NGR of the automatic transmission 6. In this table, the gear ratio correction coefficient KGRNELM is set to a larger value as the gear position value NGR is larger, that is, as the gear position of the automatic transmission 6 is set to the higher speed side.

  Next, at step 66, the target torque TRQNELMFT is calculated by multiplying the basic value TRQNELVP by the gear ratio correction coefficient KGRNELMN. Therefore, the target torque TRQNELMFT is set to a larger value as the vehicle speed VP is higher and as the gear position of the automatic transmission 6 is set to the higher speed side.

  Next, at step 67, a torque gradual reduction amount DTRQNELMFF is calculated by searching a predetermined table (not shown) according to the gear position value NGR. In this table, the torque gradually decreasing amount DTRQNELMFF is set to a larger value as the gear stage value NGR is larger and the gear stage of the automatic transmission 6 is set to the higher speed side.

  In step 68 following step 63 or 67, the current torque TRQNELMFF is set to the torque requested by the driver (hereinafter referred to as “DRV required torque”) TRQTGDRV, and this process is terminated. The DRV required torque TRQTGDRV is calculated by searching a predetermined map (not shown) according to the engine speed NE and the accelerator pedal opening AP.

  Returning to FIG. 3, in step 5 following step 4, a difference (= TRQNELMFF−TRQNELMFT) between the current torque TRQNELMFF and the target torque TRQNELMFT is calculated as a torque deviation DTRQNELMF.

  Next, in step 6, a value of a down-count delay timer (hereinafter referred to as “F / B delay timer value”) TDLYNELM is set to a predetermined time TMDLYNELM. The predetermined time TMDLYNELM is calculated by searching a predetermined map (not shown) according to the calculated torque deviation DTRQNELMF and the engine speed NE. In this map, the predetermined time TMDLYNELM is set to a larger value as the torque deviation DTRQNELMF is larger and as the engine speed NE is smaller. This is because the greater the torque deviation DTRQNELMF, the greater the amount of operation of the throttle valve until the current torque TRQNELMFF approaches the target torque TRQNELMFT, and the lower the engine speed NE, the lower the intake air flow rate and the more the throttle valve opens. This is because the delay from when the degree is changed until the intake air reaches the engine 3 increases.

  Further, as described above, the NE limit control is started when the engine speed NE becomes equal to or higher than the NE limit start speed NELMTH. Therefore, the predetermined time TMDLYNELM actually used for the NE limit control is equal to the NE limit start speed. It is calculated according to the engine speed NE substantially equal to the number NELMTH. Therefore, the predetermined time TMDLYNELM calculated as described above is a value reflecting the NE limit start rotational speed NELMTH.

  Next, in step 7, a torque non-limit flag F_TRQNELMS, which will be described later, is set to “0”, and the NE limit control torque TRQNELMT is set to the DRV request torque TRQTGDRV (step 8), and then this process ends.

  On the other hand, if the answer to step 2 is YES and the NE limit control is being executed, it is determined whether or not the F / B delay timer value TDLYNELM is 0 (step 9). If the answer is NO and the predetermined time TMDLYNELM has not elapsed since the start of NE limit control, the NE deviation DNELCM, which is essentially the difference between the engine speed NE and the target speed NELMMTCM, is set to 0 ( Step 10). As a result, the F / B term calculated in steps 12 to 14 to be described later becomes 0 based on the NE deviation DNELCMM.

  On the other hand, if the answer to step 9 is YES and a predetermined time TMDLYNELM has elapsed since the start of NE limit control, the difference between the detected actual engine speed NE and the target engine speed NELMTCM (= NE−NELMMTCM) Is calculated as the NE deviation DNELCMM (step 11).

  In step 12 following step 10 or 11, the P term TRQNELMP of the F / B term and the I term addition value DTRQNEL are calculated. The calculation of the P term TRQNELMP is performed by searching a predetermined table (not shown) according to the NE deviation DNELCMM. In this table, the P term TRQNELMP is set to a larger value as the NE deviation DNELCMM is larger.

  Further, the I term addition value DTRQNEL is calculated by searching a predetermined table (not shown) according to the NE deviation DNELCMM. In this table, the I-term added value DTRQNEL is set to a larger value as the NE deviation DNELCMM is larger.

  Next, in step 13, it is determined whether or not the torque non-limit flag F_TRQNELMS is “1”. As will be described later, the torque non-limit flag F_TRQNELMS is set to “1” when the torque limit by the NE limit control torque TRQNELMT is not substantially performed. When the answer to step 13 is NO and torque limitation by the NE limit control torque TRQNELMT is performed, the I term addition value DTRQNEL calculated in step 12 is added to the I term TRQNELMI calculated so far. The current I term TRQNELMI is calculated (step 14), and the process proceeds to step 15.

  On the other hand, if the answer to step 13 is YES and the torque limit by the NE limit control torque TRQNELMT is not performed, step 14 is skipped and the process proceeds to step 15.

  In step 15, the current torque TRQNELMFF is calculated as an F / F term. FIG. 6 shows a process for calculating the current torque TRQNELMFF. In this process, first, in step 71, the current torque calculation value trqnelmff is calculated by subtracting the torque decrease amount DTRQNELMFF calculated in step 63 or 67 of FIG. 5 from the previous current torque TRQNELMFF.

  Next, in step 72, it is determined whether or not the current torque calculation value trqnelmff is smaller than the target torque TRQNELMFT calculated in step 62 or 66 in FIG. If the answer is NO and trqnelmff ≧ TRQNELMFT, the current torque TRQNELMFF is set to the current torque calculated value trqnelmff (step 73), and this process is terminated. As the steps 71 to 73 are repeatedly executed in this way, the current torque calculation value trqnelmff and the current torque TRQNELMFF gradually decrease by the torque gradually decreasing amount DTRQNELMFF.

  On the other hand, if the answer to step 72 is YES and the gradually reduced current torque calculated value trqnelmff becomes smaller than the target torque TRQNELMFT, the current torque TRQNELMFF is set to the target torque TRQNELMFT (step 74), and this process ends.

  Returning to FIG. 3, in step 16 following step 15, the P term TRQNELMP and the I term TRQNELMI of the F / B term are added to the current torque TRQNELMFF as the F / F term calculated in step 73 or 74. Thus, the provisional value TRQNELMTBS of the NE limit control torque is calculated.

  Next, in step 17, it is determined whether or not the provisional value TRQNELMTBS is smaller than the DRV request torque TRQTGDRV. If the answer is YES and TRQNELMTBS <TRQTGDRV, the torque non-limit flag F_TRQNELMS is set to “0” (step 18) and the NE limit control torque TRQNELMT is set to the provisional value TRQNELMTBS (step 19). finish.

  On the other hand, when the answer to step 17 is NO and TRQNELMTBS ≧ TRQTGDRV, it means that the torque required by the driver is smaller than the torque to be limited, and it is not necessary to limit the torque by the NE limit control torque TRQNELMT. To do. Therefore, in order to express this, the torque non-limit flag F_TRQNELMS is set to “1” (step 20), and the NE limit control torque TRQNELMT is set to the DRV request torque TRQTGDRV (step 21), and this process is terminated. To do.

  FIG. 7 shows a process for setting the final target torque TRQTGTNES, which is the final target of the torque output by the engine 3. In this process, first, in step 81, it is determined whether or not the NE limit flag F_NELMTA is “1”.

  If the answer is NO and the NE limit control is not being executed, the final target torque TRQTGTNES is set to the DRV request torque TRQTGDRV (step 82), and this process ends.

  On the other hand, if the answer to step 81 is YES and the NE limit control is being executed, the final target torque TRQTGTNES is set to the NE limit control torque TRQNELMT (step 83), and this process ends.

  FIG. 8 shows an example of operation obtained by the NE limit control processing described so far for each shift mode. When the speed change mode shown in FIG. 5A is the S mode, as described above, the NE limit start rotational speed NELMTH is set to a value equal to the F / C rotational speed NEFC (step 36 in FIG. 4). ). In this example, the DRV required torque TRQTGDRV increases and the engine speed NE increases with time t1, but the engine speed NE increases to the F / C speed NEFC and the NE limit start speed NELMTH. Since the fuel cut and the NE limit control are not executed, the final target torque TRQTGTNES is set to the DRV request torque TRQTGDRV (step 82 in FIG. 7).

  When the engine speed NE reaches the F / C speed NEFC and the NE limit start speed NELMTH (t1), the fuel cut flag F_FC is set to “1”, and fuel cut is started. At the same time, the NE limit flag F_NELMTA is set to “1” and the NE limit control is started (steps 45 and 46 in FIG. 4), whereby the final target torque TRQTGTNES is set to the NE limit control torque TRQNELMT. (Step 83 in FIG. 7).

  As a result of the fuel cut being executed, the engine speed NE is decreased. Thereafter, when the engine speed NE falls below the return speed NERTN (t2), the fuel cut is completed, and the fuel from the injector 4 is discharged. The supply is resumed, and the engine speed NE increases again accordingly. Thereafter, NE limit control for setting the final target torque TRQTGTNES to the NE limit control torque TRQNELMT is continuously executed, whereby the engine speed NE is controlled to the target speed NELMTCM (after t3). In FIG. 9A, the target rotational speed NELMTCM is set to a value larger than the return rotational speed NERTN, but may be set to a value smaller than the return rotational speed NERTN.

  On the other hand, when the speed change mode shown in FIG. 5B is the N mode, as described above, the NE limit start rotational speed NELMTH is obtained from the F / C rotational speed NEFC in accordance with the increase amount ΔNE of the engine rotational speed NE. Is also set to a small value (step 40 in FIG. 4). In this example, the DRV request torque TRQTGDRV increases and the engine speed NE increases accordingly until the time t4, but the engine speed NE has not reached the NE limit start speed NELMTH. Neither the NE limit control nor the final target torque TRQTGTNES is set to the DRV request torque TRQTGDRV (step 82 in FIG. 7).

  When the engine speed NE reaches the NE limit start speed NELMTH (t4), the NE limit flag F_NELMTA is set to “1”, and NE limit control is started (steps 45 and 46 in FIG. 4). The final target torque TRQTGTNES is set to the NE limit control torque TRQNELMT (step 83 in FIG. 7). By this NE limit control, the engine speed NE is controlled to the target speed NELMTCM (after t5).

  As described above, according to the present embodiment, when the speed change mode is the S mode, the torque limit by the NE limit control is not performed until the engine speed NE reaches the F / C speed NEFC. In the S mode in which driving performance is important, drivability suitable for it can be obtained. In addition, since the fuel injection from the injector 4 is resumed after the engine speed reaches the F / C speed NEFC, the engine speed NE is controlled to a target speed NELMTCM smaller than the F / C speed NEFC. Thereafter, overreving of the engine 3 can be prevented.

  On the other hand, when the speed change mode is the N mode, the torque is limited by NE torque limit control before the engine speed NE reaches the F / C speed NEFC, and the engine speed NE is controlled to the target speed NELMTCM. It is possible to avoid the torque fluctuation of the engine 3 due to the execution of fuel cut and the resumption of fuel supply when the rotational speed NE reaches the F / C rotational speed NEFC. As a result, the torque of the engine 3 and the engine speed NE change smoothly, so that drivability suitable for the smoothness can be obtained in the N mode where smoothness is important.

  Further, when the speed change mode is the N mode, the NE limit start rotation speed NELMTH is set to a smaller value as the increase amount ΔNE of the engine rotation speed NE is larger, and the NE limit control is started from a lower engine rotation speed NE. Therefore, even when the increase amount ΔNE of the engine speed NE is large, the engine speed NE does not greatly overshoot the target speed NELMTCM, so that the convergence to the target speed NELMTCM can be improved, and the engine It is possible to avoid the rotational speed NE from reaching the F / C rotational speed NEFC, whereby smooth drivability can be more reliably realized when the shift mode is the N mode.

  Further, the NE limit control torque TRQNELMT is set so that the engine speed NE exceeds the NE limit start speed NELMTH and the NE limit control is started and then the F / B term (P term TRQNELMP and Pterm) until the predetermined time TMDLYNELM has elapsed. I term TRQNELMI) is set to 0 (steps 10 and 12), calculation is performed using only the F / F term (current torque TRQNELMFF) (steps 9 and 10 in FIG. 3, steps 101 and 102 in FIG. 9), and thereafter After the predetermined time TMDLYNELM has elapsed, calculation is performed using the F / F term and the F / B term (steps 9 and 11 in FIG. 3 and steps 101 and 103 in FIG. 9). Therefore, in the NE limit control, the engine speed NE can be accurately controlled with high responsiveness and convergence to the target speed NELMTCM while avoiding sudden fluctuations in the torque of the engine 3 and the engine speed NE. Smooth drivability can be achieved even better.

  9 and 10 show the NE limit control torque TRQNELMT calculation process according to a modification. This process is also executed every predetermined time. In this modification, steps 99 and 100 are added to the calculation processing of FIG. 3 according to the above-described embodiment.

  In this process, first, in steps 91 and 92, the same processes as in steps 1 and 2 of FIG. 3 are performed. When the answer to step 92 is YES and the NE limit control is being executed, it is determined whether or not the fuel cut flag F_FC is “1” (step 99). If the answer is YES and the fuel cut is being executed, the F / B delay timer value TDLYNELM is set to a predetermined time TMDLYNELM (step 100), and the process proceeds to step 101.

  On the other hand, if the answer to step 99 is NO and fuel cut is not being executed, step 100 is skipped and the routine proceeds to step 101. In Steps 101 to 113, the same processing as Steps 9 to 21 in FIG. 3 is performed, and this processing is terminated.

  On the other hand, if the answer to step 92 is NO and the NE limit control is not being executed, the same processing as steps 3 to 8 in FIG. 3 is performed in steps 93 to 98, and this processing is terminated.

  As described above, in this modified example, when steps 99 and 100 are added, when the shift mode is the S mode, the NE limit control torque TRQNELMT is set to a predetermined time after the fuel supply is resumed after the fuel cut. Until TMDLYNELM elapses, the F / B term is set to 0 and is calculated using only the F / F term. After a predetermined time TMDLYNELM elapses, the F / F term and the F / B term are used for calculation. . Therefore, starting of feedback control during fuel cut can be avoided, and the engine speed NE is made highly responsive to the target speed NELMTCM while avoiding sudden fluctuations in the torque of the engine 3 and the engine speed NE. The convergence can be controlled with high accuracy.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the embodiment, the target rotational speed NELMTCM is set to the same value between the S mode and the N mode, but may be set to a different value.

  Further, the NE limit start rotational speed NELMTH when the speed change mode is the N mode is calculated by subtracting the second predetermined value NEREF2 and the NE increase correction value DNELMTSTT from the F / C rotational speed NEFC. Instead, it may be calculated by subtracting the predetermined value and the NE increase correction value DNELMTSTT from the target rotational speed NELMTCM. Thus, the NE limit start rotational speed NELMTH is set to be surely smaller than the target rotational speed NELMMTCM, so that the NE limit control can be started from an engine rotational speed NE smaller than the target rotational speed NELMTCM.

  Further, the predetermined time TMDLYNELM is calculated in accordance with the torque deviation DTRQNELMF and the engine speed NE, but it is sufficient if it reflects a delay until the engine speed NE approaches the target speed NELMTCM. Instead of the rotational speed NE, the NE limit start rotational speed NELMTH or the F / C rotational speed NEFC may be used.

  Further, although the F / C rotational speed NEFC is a fixed value, it may be calculated according to, for example, an increase amount ΔNE of the engine rotational speed NE. In the embodiment, the F / C speed NEFC is set to a large value for protecting the engine 3, but is set to a smaller value for limiting the engine speed NE during the fail-safe action. Alternatively, NE limit control may be performed in the vicinity of the F / C rotational speed NEFC set in such a manner.

  The embodiment is an example in which the present invention is applied to a gasoline engine mounted on a vehicle, but the present invention is not limited to this, and may be applied to various engines such as a diesel engine other than a gasoline engine. Also, the present invention can be applied to engines other than those for vehicles, for example, engines for marine propulsion devices such as outboard motors having a crankshaft arranged vertically. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 ECU (1st rotation speed control means, 2nd rotation speed control means, selection means,
Predetermined rotation speed setting means, feedforward term calculation means,
Feedback term calculation means)
3 Engine (Internal combustion engine)
22 Crank angle sensor (engine speed detection means)
NE engine speed (engine speed)
NEFC fuel cut speed (upper limit speed)
NERTN Return speed NELMTH NE limit start speed (predetermined speed)
NELMTCM target speed (first target speed, second target speed)
ΔNE Engine speed increase (engine speed increase speed)
TRQNELMFF Current torque (feed forward term)
TRQNELMP P term (feedback term)
TRQNELMI I term (feedback term)
TRQNELMT NE limit control torque (target output)
DNELCMM NE deviation (deviation)
TMDLYNELM Predetermined time

Claims (4)

When the engine speed, which is the speed of the internal combustion engine, reaches the upper limit speed, the fuel supply is stopped, and then the engine speed falls below a predetermined return speed smaller than the upper limit speed. A control device for an internal combustion engine for resuming fuel supply,
Engine speed detecting means for detecting the engine speed;
After the fuel supply is resumed after the engine speed reaches the upper limit speed, the output of the internal combustion engine is set so that the engine speed becomes a first target speed smaller than the upper limit speed. First rotational speed control means for controlling;
After the detected engine speed exceeds a predetermined speed smaller than the upper limit speed, the engine speed becomes a second target speed between the upper limit speed and the predetermined speed. Second rotational speed control means for controlling the output of the internal combustion engine;
Selection means for selecting one of the first rotation speed control means and the second rotation speed control means in accordance with the operating conditions of the internal combustion engine;
A control device for an internal combustion engine, comprising:   2. The control device for an internal combustion engine according to claim 1, further comprising predetermined rotation speed setting means for setting the predetermined rotation speed to a smaller value as the speed of increase of the engine rotation speed is larger. The second rotational speed control means includes
Feedforward term calculating means for calculating a feedforward term of the target output of the internal combustion engine for controlling the engine speed to the second target speed;
Feedback term calculating means for calculating a feedback term of the target output according to a deviation between the second target engine speed and the engine speed;
The target output is calculated using the feedforward term until a predetermined time elapses after the engine speed exceeds the predetermined speed, and after the predetermined time has elapsed, the feedforward term and The control apparatus for an internal combustion engine according to claim 1, wherein the calculation is performed using the feedback term. The first rotation speed control means includes
Feedforward term calculating means for calculating a feedforward term of the target output of the internal combustion engine for controlling the engine speed to the first target speed;
Feedback term calculation means for calculating a feedback term of the target output according to a deviation between the first target rotation speed and the engine rotation speed;
The target output is calculated using the feedforward term until a predetermined time elapses after the supply of fuel is resumed after the engine speed reaches the upper limit speed, and the predetermined time elapses. 2. The control apparatus for an internal combustion engine according to claim 1, wherein calculation is performed using the feedforward term and the feedback term.

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