JP6127903B2 - Control device for turbocharged engine - Google Patents

Description

  The present invention relates to a control device for an engine with a turbocharger mounted on a vehicle, and relates to a countermeasure against a so-called turbo lag.

  Conventionally, it is known that an engine mounted on a vehicle such as an automobile has an output response delay with respect to the operation of the occupant. In particular, when a turbocharger is provided, even if the accelerator pedal operation is performed in an operation region where the exhaust gas flow rate is low, sufficient turbocharging is required until the rotational speed of the turbine becomes higher than a predetermined level due to an increase in the exhaust gas flow rate. Is not performed, and the rise of the engine output is delayed (so-called turbo lag).

  When this happens, the start of the driving force of the vehicle will also be delayed, so the occupant feels that the driving force of the vehicle has not caught up for a while with respect to his accelerator stepping operation, When the boost pressure rises and the driving force rises, the user feels uncomfortable. That is, a step is formed in the rising of the driving force with respect to the accelerator depressing operation, so that the turbo lag is emphasized and an uncomfortable feeling is generated.

  Regarding such a problem of turbo lag, for example, in the control device for an internal combustion engine with a turbocharger described in Patent Document 1, the turbocharger starts to operate after the accelerator stepping operation is performed, and the supercharging pressure increases. In the meantime, the engine torque is reduced in advance by ignition timing retard control or the like. Then, by gradually increasing the engine torque until the supercharging pressure rises, it is difficult to feel the step when the driving force rises as described above.

JP 2008-014281 A

  However, in spite of the accelerator stepping operation being performed as in the conventional example, the purpose of reducing the engine torque is that the increase in the engine torque at the initial stage of acceleration with respect to the accelerator stepping operation is suppressed. In this case, the occupant feels dissatisfied with the acceleration response of the vehicle with respect to his / her accelerator operation.

  In view of this point, the object of the present invention is to reduce the acceleration response to the accelerator depressing operation as much as possible while adjusting the engine output so that the occupant is less likely to feel discomfort due to the so-called turbo lag. There is to be no.

  In order to achieve the above object, the inventor of the present invention does not suppress the increase in the engine output immediately after the accelerator stepping operation, but when the engine output is stagnated by a turbo lag more than a predetermined value, The sudden increase (step difference) was suppressed. For this purpose, when the target driving force in the engine control is once decreased and then gradually increased, the present inventor can determine that the gradual increase rate of the target driving force is appropriately set so that the occupant can drive the driving force. I noticed that it was difficult to feel the level difference.

  That is, the present invention is directed to a control device for an engine with a turbocharger mounted on a vehicle, and the required driving force determined according to at least the accelerator operation amount of the occupant is an actual driving force of the vehicle. Driving force restriction control for reducing the required driving force in order to restrict the increase in the actual driving force when it is determined that the degree of change in the actual driving force is less than or equal to a predetermined value. It is something to execute.

In the present invention as the driving force restriction control, the required driving force is once reduced as described above, and then gradually increased according to the accelerator operation amount. Based on the operation amount and the degree of change in the actual driving force before decreasing once as described above , the gradual increase rate increases as the accelerator operation amount increases and the degree of change in the actual driving force increases. I set it to be.

  According to the specific matter described above, first, when an occupant depresses the accelerator while the vehicle is running, the output of the engine is increased so as to follow the required driving force that is increased accordingly. At this time, since the engine output is not reduced immediately after the accelerator stepping operation as in the control technique of the conventional example (Patent Document 1), the acceleration response immediately after the accelerator stepping operation is not reduced.

  When the increase in engine output is delayed due to the turbo lag, the required driving force deviates from the actual driving force of the vehicle (that is, the deviation of the actual driving force with respect to the required driving force becomes greater than a predetermined value). The degree of change in the actual driving force becomes less than a predetermined level, and the occupant feels the stagnation of the driving force. On the other hand, once the driving force restriction control is started and the required driving force is once reduced, the rapid increase of the actual driving force after the stagnation can be restricted.

  In addition, the actual driving force can be increased smoothly by gradually increasing the required driving force. That is, as the knowledge obtained by the present inventor, when the actual driving force temporarily stagnated by the turbo lag as described above increases again, the stronger the degree of stagnation, the higher the level of the subsequent actual driving force. However, if the degree of stagnation is weak, it is found that it is difficult to feel the step against the subsequent increase in driving force.

  In addition, there is a correlation with the amount of accelerator operation in how to feel the step of the driving force, and the greater the accelerator operation amount, the stronger the will of acceleration, so even if the rising of the driving force after stagnation is somewhat steep, The occupant is difficult to feel the level difference. On the other hand, when the accelerator operation amount is small, the occupant tends to prefer a gentle behavior of the vehicle. Therefore, if the driving force suddenly rises after a stagnation, it is easy to feel a step.

Therefore, the required driving force is once reduced and gradually increased as in the above-mentioned specific matter, and the incremental rate of the required driving force at that time is stagnant (that is, temporarily reduced as described above). Based on the previous degree of change in actual driving force ( the degree of stagnation of actual driving force) and the amount of accelerator operation , the greater the degree of change in actual driving force and the greater the amount of accelerator operation, the gradual increase If the rate is set to be large, it becomes difficult for the occupant to feel the difference in driving force caused by the turbo lag. That is, it is possible to sufficiently reduce the decrease in the acceleration response to the accelerator stepping operation while adjusting the engine output so that the occupant does not feel a sense of incongruity at the step of the driving force.

Note that, as described above, the degree of change in the actual driving force in the determination of the start of the driving force regulation control is equal to or less than a predetermined value, for example, the amount of change or rate of change in the actual driving force over a predetermined period (the amount of change per time ). Similarly, the amount of change and the rate of change may be used for the degree of change in the actual driving force for setting the gradual increase rate of the required driving force. The two “degrees of change ” may be the same parameter or different parameters.

Preferably, as described above, the gradual increase rate of the required driving force determined based on the accelerator operation amount of the occupant and the degree of stagnation (change degree ) of the actual driving force due to the turbo lag, and further, the stagnation time of the actual driving force You may make it change according to. That is, the longer the stagnation time of the actual driving force, the easier it is for the occupant to feel a step with respect to the subsequent increase in driving force. In this case, the gradual increase rate of the driving force may be made smaller.

  In this case, the shorter the stagnation time of the actual driving force, the greater the subsequent increase rate of the driving force.However, if the stagnation time is shorter, the occupant will integrate the increase in the actual driving force after the stagnation, including the stagnation period. It feels like acceleration, so it ’s hard to remember. Note that the decrease change amount of the required driving force that is once reduced with the start of the driving force restriction control may be changed according to the accelerator opening, the degree of stagnation of the actual driving force, or the stagnation time.

  As for the timing of starting the driving force regulation control, the actual driving force is determined not only by considering the stagnation of the actual driving force as described above, but also by considering the followability of the actual driving force with respect to the required driving force. The driving force restriction control may be started when it is considered that the likelihood of following the above is low. If it carries out like this, according to the situation where driving force stagnates, the timing which regulates it can be judged appropriately, and it becomes possible to make change of driving force from stagnation to increase more natural.

According to the control device for an engine with a turbocharger according to the present invention, the actual driving force of the vehicle does not increase sufficiently with respect to the increase in the required driving force due to the accelerator operation of the occupant. When the increase in the driving force is stagnant, the step of the actual driving force can be reduced by once reducing the required driving force. Then, by setting the gradual increase rate of the required driving force thereafter based on the accelerator operation amount and the degree of stagnation (change degree ) of the actual driving force, it is difficult for the passenger to feel the step of the driving force. can do.

  That is, it is possible to prevent the acceleration response from deteriorating to the accelerator stepping operation as much as possible while adjusting the engine output so that the occupant does not feel a sense of incongruity at the step of the driving force caused by the so-called turbo lag.

It is a schematic structure figure showing an example of an engine with a turbocharger concerning the present invention. It is a timing chart figure showing change of demanded driving force, actual driving force, and acceleration of vehicles when not restricting driving force. It is a flowchart figure which shows the procedure of driving force control control. It is explanatory drawing which shows typically the correction | amendment of the request | requirement driving force in driving force control control. It is a figure which shows an example of the map which set the gradual increase rate of the request | requirement driving force according to the accelerator opening and the variation | change_quantity of the actual driving force in a stagnation. FIG. 3 is a view corresponding to FIG. 2 for the case where the driving force restriction control of the present invention is performed. FIG. 5 is a diagram corresponding to FIG. 4 according to another embodiment in which the required driving force is corrected in consideration of the stagnation time of the actual driving force.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. This embodiment demonstrates the case where this invention is applied to the gasoline engine 1 with the turbocharger mounted in a vehicle. First, the schematic configuration of the engine 1 will be described with reference to FIG. 1. The engine 1 is a four-cylinder gasoline engine, and the pistons 1c are housed in four cylinders 1b (cylinders) formed in the cylinder block 1a. Has been. A cylinder head 1d is fastened on the cylinder block 1a to close the upper end opening of the cylinder 1b.

  Although illustration is omitted, the reciprocating motion of the piston 1c in the cylinder 1b is converted into rotation of the crankshaft by the connecting rod. Then, the rotation of the crankshaft, that is, the rotation output of the engine 1 is transmitted to the drive wheels of the vehicle via the transmission and the drive shaft. Further, a signal rotor is attached to the crankshaft, and a known crank position sensor 301 that generates a pulse-like signal (voltage pulse) at every predetermined angle according to its rotation is disposed. The engine speed can be calculated from the output signal of the crank position sensor 301.

  In the cylinder 1b, a combustion chamber is formed between the top surface of the piston 1c and the lower surface of the cylinder head 1d, and an in-cylinder injector 2a is disposed so as to inject fuel toward the combustion chamber. Has been. The in-cylinder injectors 2a of the four cylinders 1b are connected to a common high-pressure fuel delivery pipe 20a, and the fuel supplied from a fuel tank by a fuel pump (not shown) is the high-pressure fuel delivery pipe 20a. Is distributed to the in-cylinder injector 2a of each cylinder 1b.

  A spark plug 3 is disposed in the cylinder head 1d so as to face the combustion chamber in the cylinder 1b, and its ignition timing is adjusted by an igniter (not shown). An intake passage 11 and an exhaust passage 12 are provided so that air is sucked into the combustion chamber of each cylinder 2a and burned gas is discharged. A part of the intake passage 11 is constituted by an intake port (not shown) formed in the cylinder head 1d and an intake manifold 11a. Similarly, a part of the exhaust passage 12 is an exhaust port (not shown). And an exhaust manifold 12a.

  Although not shown, intake and exhaust valves are provided to open and close the intake port and exhaust port, respectively, and the valve operating system that operates these valves is a DOHC type in which the intake side and the exhaust side are independent from each other It is said that. That is, two camshafts are provided to operate the intake valve and the exhaust valve, respectively, and the rotation of the crankshaft is transmitted via a timing chain or the like. Further, a known cam position sensor 302 for detecting the rotational position of the intake side camshaft is provided.

  The intake passage 11 is provided with a throttle valve 5 for restricting the air (intake) sucked into the cylinder 1 b, and the opening degree (throttle opening degree) is adjusted by the operation of the throttle motor 6. The intake passage 11 is provided with an air cleaner 7 for filtering the intake air, an air flow meter 304 for detecting the intake air amount, and a compressor impeller 102 of the turbocharger 100 described later. An intercooler 8 for cooling the intake air that has been compressed and heated is also provided.

  Further, an intake air temperature sensor 307 and an intake manifold pressure sensor 308 are also provided in the intake passage 11, and a port injection injector 2b is also provided so as to inject fuel facing the intake port. Similarly to the in-cylinder injector 2a, the port injector 2b is provided corresponding to each of the four cylinders 1b and connected to a common low pressure fuel delivery pipe 20b. Fuel is distributed in the pipe 20a.

On the other hand, a three-way catalyst 9 for purifying HC, CO, NOx in the exhaust gas is disposed in the exhaust passage 12 on the downstream side of the turbine wheel 101 of the turbocharger 100 (downstream side of the exhaust flow). An air-fuel ratio (A / F) sensor 309 having a linear characteristic with respect to the air-fuel ratio is disposed upstream of the three-way catalyst 9 (upstream of the exhaust flow), and downstream of the three-way catalyst 9 In accordance with the oxygen concentration, an O ₂ sensor 310 showing a steep characteristic in the vicinity of the stoichiometric is disposed.

-Turbocharger-
The turbocharger 100 includes the turbine wheel 101 disposed in the exhaust passage 12 and the compressor impeller 102 disposed in the intake passage 11 as described above, and the turbine wheel 101 and the compressor impeller 102 are connected to the connecting shaft. 103 connected to each other. The turbine wheel 101 in the exhaust passage 12 is rotated by the exhaust flow, and the intake air is compressed by the compressor impeller 102 that rotates integrally therewith, and is supplied to the combustion chamber of each cylinder 1b (supercharging).

  The turbine wheel 101 is accommodated in the turbine housing 110, and the compressor impeller 102 is accommodated in the compressor housing 120. The turbine housing 110 and the compressor housing 120 are attached to both sides of the center housing 130. The compressor impeller 102, the compressor housing 120, and the like constitute a compressor 100B, and the turbine wheel 101, the turbine housing 110, and the like constitute a turbine 100A.

  Further, in the turbocharger 100 of this example, an exhaust bypass passage 104 that communicates the upstream side and the downstream side of the turbine wheel 101 (bypassing the turbine wheel 101), and a wastegate valve that opens and closes the exhaust bypass passage 104 105 is provided. By adjusting the opening degree of the waste gate valve 105 and adjusting the amount of exhaust gas that bypasses the turbine wheel 101, the supercharging pressure can be controlled.

  In the present embodiment, an EGR passage 201 is disposed from the exhaust manifold 12a upstream of the turbine wheel 101 to the intake manifold 11a, and a part of the exhaust gas is introduced into the intake air. An EGR cooler 202 and an EGR valve 203 are disposed in the middle of the EGR passage 201, and the EGR device 200 is configured including these devices.

-ECU-
Although not shown in the figure, ECU 500 is a known unit including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a backup RAM, and the like. The CPU executes various arithmetic processes based on various control programs and maps stored in the ROM. In addition, the RAM temporarily stores calculation results from the CPU, data input from each sensor, and the like, and the backup RAM stores data to be saved when the engine 1 is stopped, for example.

In addition to the crank position sensor 301, the cam position sensor 302, the air flow meter 304, and the throttle opening sensor 305, the ECU 500 detects an operation amount (accelerator opening Acc) of the accelerator pedal 10 by a vehicle occupant. An accelerator opening sensor 306 is also connected. In addition, the intake air temperature sensor 307, the intake manifold pressure sensor 308, the air-fuel ratio sensor 309, and the O ₂ sensor 310 are also connected to the ECU 500.

  Furthermore, a transmission ECU 600 that controls the transmission is also connected to the ECU 500 so that necessary information can be exchanged with the ECU 500. For example, transmission ECU 600 to ECU 500 are provided with vehicle speed information calculated by a signal from an output shaft rotational speed sensor (not shown) of the transmission.

  ECU 500 executes various control programs based on signals from the various sensors and information from transmission ECU 600, thereby controlling fuel injection amount by in-cylinder injector 2a and port injector 2b. Various controls of the engine 1 including control of the ignition timing by the spark plug 3 and control of the intake amount by the throttle valve 5 are executed.

  For example, the ECU 500 calculates the required driving force Preq for the vehicle based on the accelerator opening Acc detected by the accelerator opening sensor 306 and the vehicle speed provided from the transmission ECU 600. In consideration of the gear ratio, the throttle motor 6 of the throttle valve 5, the in-cylinder injector 2a, and the port injector 2b are controlled so that the engine torque corresponding to the required driving force Preq is output. At the same time, the spark plug 3 is energized at a suitable ignition timing according to the operating state of the engine 1.

  In addition, the ECU 500 executes a program for driving force restriction control at the time of acceleration described below. With this, the ECU 500 executes an engine control device that executes the driving force restriction control according to the present invention. It is composed.

-Driving force regulation control-
Next, a description will be given of the driving force restriction control executed by the ECU 500 during acceleration (when the engine 1 is in acceleration transition). In the engine 1 having the turbocharger 100 as in the present embodiment, even if the accelerator pedal operation is performed in the operation region where the exhaust gas flow rate is small, the engine 1 is in a period until the rotation of the turbine wheel 101 starts up due to the increase in the exhaust gas flow rate. Not enough supercharging. For this reason, a response delay (turbo lag) occurs from when the accelerator is depressed until the output of the engine 1 rises.

  As an example, as shown in FIG. 2, when the accelerator pedal is depressed at time t0 (when there is an acceleration request), the required driving force Preq rises stepwise, but there is a delay (turbo lag) in the increase in engine torque. Therefore, the actual driving force Pact of the vehicle does not easily rise. That is, the actual driving force Pact does not increase sufficiently for several seconds even though the occupant continues the accelerator stepping operation (the required driving force Preq is constant after time t1).

  The actual driving force Pact shown in FIG. 2 is a value calculated based on the engine torque in consideration of the transmission gear ratio and the differential reduction ratio. The actual driving force Pact increases until time t2, but thereafter time t3. Until then, it is almost constant (stagnation). At this time, the value of acceleration a representing the driving force actually generated in the vehicle (the differential value of the vehicle speed spd, the detected value by the G sensor, etc.) is also substantially constant, similar to the calculated actual driving force Pact. The occupant who feels this acceleration a feels that the driving force of the vehicle does not catch up with the accelerator depression operation, that is, is stagnant.

  When the supercharging pressure rises at time t3 (not shown in the figure) and the engine torque suddenly rises, the actual driving force Pact rises in steps as shown by the solid line, so that the occupant feels an acceleration shock. become. That is, the driving force (acceleration a) that has been stagnant until then rises in a step shape, so that the turbo lag is emphasized and the passenger feels uncomfortable.

  On the other hand, in the present embodiment, as described above, the actual driving force Pact of the vehicle is stagnant and it is considered that the possibility of following the required driving force Preq is low. This makes it difficult for the occupant to feel uncomfortable (driving force regulation control). At this time, as will be described below, the required driving force Preq is once decreased in response to the stagnation of the actual driving force Pact and then gradually increased β after increasing the required driving force Preq (described later). Is set according to the degree of stagnation of the actual driving force Pact and the accelerator opening Acc.

  Hereinafter, the driving force restriction control executed in the ECU 500 will be specifically described with reference to the flowchart of FIG. The illustrated control routine is repeatedly executed by the ECU 500 at predetermined time intervals (for example, every several tens of msec).

  First, in step ST101, it is determined whether or not the vehicle is accelerating. Specifically, for example, it is determined whether or not the amount of change per unit time of the accelerator opening Acc is equal to or greater than a predetermined acceleration determination threshold value. If the determination result is negative (NO), the process returns. If the determination is affirmative (YES), that is, the amount of change in the accelerator opening Acc is equal to or greater than the acceleration determination threshold. Proceed to

  Note that the acceleration determination threshold value may be set to an appropriate value by experiment / calculation in consideration of the target engine model. For example, the acceleration determination threshold may be set to 20% / sec to 30% / sec to determine whether or not the vehicle is accelerating. However, the present invention is not limited to this value, and other values are adopted. May be. Further, the acceleration may be determined based on other engine operating conditions such as the throttle opening obtained from the output signal of the throttle opening sensor 305, or the acceleration may be determined by other known methods. .

  In step ST102, a calculation is performed to determine whether or not the increase in driving force is stagnating for a predetermined value or more. Specifically, for example, when all of the following stagnation determination conditions are satisfied, it is determined that the stagnation is equal to or greater than a predetermined value. As the stagnation determination condition, first, the deviation amount (absolute value) of the actual driving force Pact with respect to the required driving force Preq is greater than or equal to a predetermined value, and secondly, the change rate of the required driving force Preq is substantially smaller than the predetermined value. Third, the change rate of the actual driving force Pact is also less than a predetermined value and very small.

  The first condition is that the actual driving force Pact deviates from the passenger's request. For example, if the actual driving force Pact stays at 3000N even though the required driving force Preq is 5000N, the absolute value of the deviation is 2000N. Therefore, when the shortage of the actual driving force Pact is 2000N or more It can be determined that the first condition is satisfied. However, the value is not limited to this value, and a suitable value may be set by experiment / calculation in consideration of the target vehicle type or engine model.

  The second condition is that the increase / decrease width of the accelerator opening Acc is small, and it is determined that the occupant is stepping on the accelerator pedal at his / her will. The third condition is nevertheless the actual driving force. It is determined that Pact has not increased so much (the degree of change is not more than a predetermined value). For example, it is determined that the second condition is satisfied when the absolute value (change amount per unit time) of the change rate of the required drive force Preq is 10% / sec or less, and the increase change rate of the actual drive force Pact (per unit time) It may be determined that the third condition is satisfied when the increase change amount) is 15% / sec or less. However, the value is not limited to this value, and a suitable value may be set by experiment / calculation in consideration of the target vehicle type or engine model.

  Even though the accelerator stepping operation is continuously performed, the actual driving force Pact does not increase so much, and the deviation amount (absolute value) of the actual driving force Pact with respect to the required driving force Preq is large. When it remains, it is determined that the stagnation state is equal to or greater than the predetermined value. That is, in step ST103, it is determined whether or not all the first to third conditions are satisfied. If even one of the conditions is not satisfied, a negative determination (NO) is made and the process returns to step ST102. If it is established and the determination is affirmative (YES), the process proceeds to step ST104.

  In step ST104, the stagnation flag for measuring the stagnation time of the driving force (timer counting) is turned on, and the calculation for determining the followability of the driving force is performed as follows. Specifically, for example, a followability determination threshold value for determining the followability to the required drive force Preq based on the increasing change rate of the actual drive force Pact is calculated. That is, if the increase change rate of the actual driving force Pact stagnating is further reduced as described above, it is considered that there is no possibility of following the deviated requested driving force Preq. For example, the increase change rate of the actual driving force Pact may be 10% / sec.

  However, the values are not limited to the above values, and may be set to suitable values by experiments and calculations in consideration of the target vehicle type and engine model. Further, the determination is made not only based on the increasing change rate of the actual driving force Pact but also considering whether the deviation amount (absolute value) from the required driving force Preq at that time is larger than a predetermined value. Also good. Instead of the increasing change rate of the actual driving force Pact, the determination may be made based on the decreasing change rate of the deviation amount (absolute value) between the actual driving force Pact and the required driving force Preq.

  Subsequently, in step ST105, it is determined whether or not the increasing change rate of the actual driving force Pact is equal to or less than the follow-up determination threshold value. If the determination result is negative (NO), the control routine is terminated once, but an affirmative determination (YES) ), That is, the rate of increase in the actual driving force Pact ≦ the follow-up determination threshold value, and if it is determined that there is no prospect of following, the process proceeds to step ST106 to restrict the subsequent increase in the actual driving force Pact. The required driving force Preq is corrected as follows. At this time, the stagnation flag is turned off.

  That is, in this example, it is determined that the required driving force Preq deviates from the actual driving force Pact, the increase change amount of the actual driving force Pact is less than a predetermined value, and the actual driving force Pact is stagnating more than a predetermined value. In addition, when it is determined that the actual driving force Pact is unlikely to follow the required driving force Preq, the required driving force Preq is corrected. Specifically, for example, as shown schematically in FIG. 4, the required driving force Preq is first decreased at a stretch by a predetermined decrease correction amount α and then gradually increased at a predetermined incremental rate β.

  By reducing the required driving force Preq once in this way, it is possible to restrict the actual driving force Pact from increasing in steps, and thereafter the actual driving force Pact corresponding to the gradually increasing required driving force Preq. It can be increased smoothly. Thereby, even if there is a stagnation of the driving force due to the turbo lag, it is possible to realize a sense of acceleration that is integrated with the subsequent increase of the driving force, and to sufficiently relieve the passenger's uncomfortable feeling.

  Specifically, the reduction correction amount α and the gradual increase rate β of the required driving force Preq may be set to values that are adapted through experiments and calculations in consideration of the target vehicle type, engine model, and the like. The amount α is preferably set so that the required driving force Preq is somewhat larger than the actual driving force Pact to prevent control overshoot. Further, as an example, as shown in FIG. 4, the gradual increase rate β is preferably changed according to the degree of stagnation of the actual driving force Pact and the accelerator opening Acc.

  That is, as a result of the prototype of the engine as described above and the actual vehicle evaluation being repeated by the inventors of the present invention, the following knowledge was obtained. First, as described above, when the actual driving force Pact temporarily stagnated due to the turbo lag increases again, the stronger the degree of stagnation, the easier it is to feel a step when the actual driving force Pact increases thereafter. It was found that if the degree of is weak, it is difficult to feel a step in the subsequent increase in the actual driving force Pact.

  In addition, there is a correlation between the ease of feeling of the driving force step and the accelerator opening Acc, and the greater the accelerator opening Acc, the stronger the willingness of acceleration. Even if there is, step is hard to feel. On the other hand, when the accelerator opening degree Acc is small, the occupant tends to prefer a gentle behavior of the vehicle, and if the actual driving force Pact suddenly rises after stopping, it is easy to feel a step.

Based on such knowledge, in the present embodiment, the incremental driving rate β when the target driving force Preq is once decreased and then gradually increased as described above is maintained while stagnating as described above (that is, It is appropriately set based on the degree of change in the actual driving force Pact (before reduction), that is, the degree of stagnation and the accelerator opening Acc. Accordingly, it is possible to make it difficult for the occupant to feel the difference in driving force caused by the turbo lag.

More specifically, as schematically shown in FIG. 4, when the increase change amount ΔPact of the actual driving force Pact during stagnation is small (indicated by a one-dot chain line in the example of the figure), it does not appear in FIG. When the accelerator opening degree Acc is small , the gradual increase rate β is set to a smaller value to restrict the increase in the actual driving force Pact more strongly. On the other hand, when the increase change amount ΔPact of the actual driving force during stagnation is large (indicated by a two-dot chain line in the example in the figure), or when the accelerator opening Acc is large , the gradually increasing rate β is set to a larger value, The driving force is increased relatively quickly.

  In this embodiment, in order to suitably set the gradually increasing rate β of the required driving force Preq in accordance with the increase change amount ΔPact of the actual driving force during the stagnation and the accelerator opening Acc, A suitable value of the gradual increase rate β corresponding to each accelerator opening Acc is adapted by experiment, calculation, etc., and set to a map as shown in FIG. This map is stored in the ROM of the ECU 500 and is referred to when driving force restriction control is performed.

  Thus, when the required driving force Preq once decreased by the decrease correction amount α is gradually increased in the driving force regulation control, the increase change amount of the actual driving force before being decreased (that is, during the stagnation). The gradually increasing rate β of the required driving force Preq is suitably set according to ΔPact and the accelerator opening Acc, and the control target value of the engine torque is changed accordingly, and the throttle opening, the fuel injection amount, and the ignition The timing is controlled.

  As a result, during the acceleration transition of the engine 1, a sudden increase in the engine torque after being temporarily stagnated by the turbo lag is regulated, and the engine torque after the stagnating and thus the actual driving force of the vehicle are smoothly increased. Hereinafter, an example of changes in the required driving force Preq, the actual driving force Pact, the vehicle acceleration a, and the like in such driving force restriction control will be described with reference to the timing chart of FIG.

  First, when the accelerator pedal is depressed at time t0, the required driving force Preq rises stepwise as in the case described above with reference to FIG. 2 (when the driving force restriction control is not performed), but the actual driving of the vehicle Power Pact does not easily rise. From the time t1 to the time t3, the actual driving force Pact does not increase so much and is stagnant, although the required driving force Preq is substantially constant corresponding to the accelerator opening Acc.

  When the increase rate of change in the actual driving force Pact becomes equal to or less than a predetermined value (for example, 15% / sec) (time t2), the deviation (absolute value) of the actual driving force Pact with respect to the required driving force Preq at this time is a predetermined value. (For example, 200 N) or more and the change rate of the accelerator opening degree Acc is a predetermined value (for example, 10% / sec) or less, and therefore, all of the first to third conditions for the stagnation determination are satisfied, and the predetermined value or more (Stagnation flag is on).

  On the other hand, at that time (time t2), the increase change rate of the actual driving force Pact is not yet less than the followability determination threshold (for example, 10% / sec), and the driving force restriction control is not started. Thereafter, when the rate of increase in the actual driving force Pact further decreases and becomes less than the followability determination threshold at time t3, it is determined that the actual driving force Pact is unlikely to follow the required driving force Preq, and the driving force is determined. The regulation control is started. At this time, the stagnation flag is turned off.

  When the control control of the driving force is started, the required driving force Preq is once decreased by the decrease correction amount α, and then gradually increased corresponding to the increase change amount ΔPact of the actual driving force during the stagnation and the accelerator opening Acc. It gradually increases with the rate β, and even if the boost pressure rises, the engine torque does not increase rapidly. As a result, the actual driving force Pact rises smoothly from around time t4 in the example shown in the figure, and the acceleration a of the vehicle rises smoothly without any difference accordingly.

  Therefore, according to the control device for the turbocharged engine according to the present embodiment, the actual driving force Pact deviates from the required driving force Preq that increases when the vehicle is accelerated, and the change in the increase is extremely large. When it is determined that the stagnation state is smaller than a predetermined value, the required driving force Preq is once decreased to restrict the rapid increase in the actual driving force Pact after the stagnation, and then the actual driving force Pact when increasing thereafter. The step can be reduced.

  In addition, the increase rate β of the required driving force Preq, which is once increased and then gradually increased, is increased to indicate the degree of stagnation of the accelerator opening degree Acc representing the occupant's intention to accelerate and the actual driving force Pact. By suitably setting it in correspondence with the amount ΔPact, it is possible to make it difficult to feel the step of the actual driving force Pact.

  That is, according to the present embodiment, the acceleration response to the accelerator stepping operation is reduced as much as possible while the engine 1 is controlled so that the passenger does not feel a sense of incongruity in the step of the actual driving force Pact caused by the so-called turbo lag. Can not be.

-Other embodiments-
The description of the above-described embodiment is merely an example, and is not intended to limit the configuration or use of the present invention. For example, in the above-described embodiment, when it is determined that the actual driving force Pact is more than a predetermined stagnation and it is determined that the actual driving force Pact is not expected to follow the required driving force Preq, the subsequent driving force restriction control is started. However, the present invention is not limited to this. For example, if it is determined that the actual driving force Pact is more than a predetermined stagnation, the driving force regulation control may be started regardless of the likelihood of following the required driving force Preq. Good.

  In the above-described embodiment, the determination of whether the first to third conditions are satisfied is performed in order to determine whether or not the actual driving force Pact is more than a predetermined value. However, the present invention is not limited to this. For example, if it is determined that the second condition, that is, the increase / decrease width of the accelerator opening Acc is small, if both the first and third conditions are satisfied, it is determined that the stagnation is equal to or greater than a predetermined value. Also good.

  Further, in the above-described embodiment, as shown in FIG. 4 and FIG. 5, the gradual increase rate β of the required driving force Preq in the driving force restriction control is set according to the increase change amount ΔPact of the actual driving force Pact during the stagnation. However, this may be changed according to the increasing change rate (the increasing change amount per unit time) of the actual driving force Pact.

  Further, not only the gradual increase rate β of the required driving force Preq but also the decrease correction amount α may be changed according to the degree of stagnation of the actual driving force Pact and the accelerator opening Acc. For example, in consideration of the fact that the longer the stagnation time of the actual driving force Pact is, the more easily the occupant feels uncomfortable with the subsequent increase in the driving force, the decrease correction amount α is increased as the stagnation time is increased. It may be possible to restrict the level of

  In that case, the gradual increase rate β may be changed according to the length of time during which the actual driving force Pact is stagnant. For example, as schematically shown in FIG. 7, it is conceivable to change the decrease correction amount α and the increase correction rate β according to the stagnation time Δt. In the example of FIG. 7, when the stagnation time Δt is long (Δt1 in the example of the figure), the decrease change amount α of the required driving force Preq is increased, the required driving force Preq is decreased to a smaller value, and then gradually increased. The rate β is set to a small value. On the other hand, when the stagnation time Δt is short (Δt2 in the example in the figure), the decrease change amount α of the required driving force Preq is set to a small value, and the gradually increasing rate β thereafter is set to a large value, so that the driving force is relatively fast. To increase. This is advantageous in ensuring acceleration response of the vehicle.

  Furthermore, although the said embodiment demonstrated the case where this invention was applied to a gasoline engine as an example, it is not limited to this, This invention is applicable also to other engines, such as a diesel engine. . Further, the present invention can be applied to an engine of a hybrid vehicle in which an electric motor is mounted in addition to the engine as a driving force source.

  In the present invention, by appropriately regulating the subsequent increase in the driving force against the delay in the response of the driving force of the vehicle due to the turbo lag, it is possible to sufficiently alleviate the passenger's uncomfortable feeling while suppressing the decrease in the acceleration response as much as possible. It is particularly effective when applied to a turbocharged engine mounted on a passenger car.

1 engine (engine with turbocharger)
100 Turbocharger 500 ECU (driving force regulating means)
Acc accelerator opening (accelerator operation amount)
Preq Required driving force β Increasing rate of required driving force Pact Actual driving force ΔPact Increase amount of actual driving force ( degree of change in actual driving force before decrease)

Claims (1)

A control device for an engine with a turbocharger mounted on a vehicle,
If it is determined that at least the required driving force determined according to the accelerator operation amount of the passenger deviates from the actual driving force of the vehicle and the degree of change in the actual driving force is less than or equal to a predetermined value, the subsequent actual driving In order to restrict the increase in force, the driving force restriction control for reducing the required driving force is executed,
After the required driving force is once reduced as the driving force regulation control, the required driving force is gradually increased according to the accelerator operation amount, and the gradually increasing rate of the required driving force is set as the accelerator operation amount. Based on the degree of change in the actual driving force before the decrease , the gradual increase rate is set to increase as the accelerator operation amount increases and the degree of change in the actual driving force increases. An engine control device with a turbocharger.

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