JP2012007486A - Internal combustion engine control apparatus - Google Patents

Abstract

[PROBLEMS] To suppress fluttering of a throttle valve in an unstable engine speed at start-up.
The control apparatus for an internal combustion engine detects a start state of the internal combustion engine and an engine speed of the internal combustion engine, calculates a target throttle opening for realizing a target torque of the internal combustion engine, and also sets a target throttle. When calculating the opening, the air response delay is compensated based on the air response delay compensation amount corresponding to the engine speed. Further, the control device for the internal combustion engine determines whether or not the engine speed is unstable based on the change in the engine speed, detects the starting state of the internal combustion engine, and the engine speed is not correct. If it is determined to be stable, the air response delay compensation amount is limited.
[Selection] Figure 2

Description

  The present invention relates to a control device for an internal combustion engine.

  In Patent Document 1, when a target throttle opening for obtaining a target torque is obtained, a discrete engine speed obtained by discretizing an actual measured value of the engine speed of the internal combustion engine with a predetermined step width is obtained. It is disclosed that the target throttle opening is calculated according to the engine speed and the target torque.

JP 2008-286074 A JP 2008-280984 A JP 2008-095630 A JP 2007-071047 A

  In the above prior art, the target throttle opening is calculated by compensating for the air delay. Here, the response delay compensation amount of air is calculated according to the engine speed. Therefore, when response delay compensation is performed when the engine speed at the time of starting is unstable, it is conceivable that the throttle valve flutters due to a sudden change in the engine speed. The fluttering of the throttle valve is not preferable because it can reduce the durability of the throttle.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an improved control device for an internal combustion engine that can suppress fluttering of the throttle valve even when the engine speed at the time of starting is unstable. .

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
Engine speed detecting means for detecting the engine speed of the internal combustion engine;
Throttle opening calculation means for calculating a target throttle opening for realizing the target torque of the internal combustion engine;
Response delay compensation means for compensating for an air response delay based on an air response delay compensation amount according to the engine speed when calculating the target throttle opening;
A starting state detecting means for detecting a starting state of the internal combustion engine;
Engine speed determining means for determining whether the engine speed is unstable based on the change in the engine speed;
A response delay compensation limiting means for limiting a response delay compensation amount of the air when a starting state of the internal combustion engine is detected and it is determined that the engine speed is unstable;
Is provided.

According to a second invention, in the first invention,
An air flow rate detecting means for detecting an air flow rate introduced into the internal combustion engine;
Correction means for correcting the target throttle opening according to the air flow rate;
Water temperature detecting means for detecting the water temperature of the internal combustion engine;
Water temperature determining means for determining whether or not the water temperature is lower than a reference temperature;
A correction limiting means for limiting the correction of the target throttle opening according to the air flow velocity when it is determined that the water temperature is lower than a reference temperature;
Is further provided.

  According to the first aspect of the invention, the air response delay compensation amount is calculated according to the engine speed, and the throttle opening that compensates for the response delay can be calculated accordingly. Here, for example, when the engine speed is not stable, such as when the internal combustion engine is started, the response delay compensation amount calculated according to the engine speed greatly changes. If the throttle opening is compensated for the response delay based on such a response delay compensation amount, the fluctuation of the throttle opening becomes large and the throttle valve flutters. In this regard, according to the first invention, it is determined whether or not the engine speed is unstable. If it is determined that the engine speed is unstable, the amount of air response delay compensation can be limited. Therefore, it is possible to prevent the throttle valve from fluttering when the engine speed is unstable.

  According to the second aspect of the invention, the target throttle opening can be corrected according to the air flow rate introduced into the internal combustion engine. Here, when the water temperature of the internal combustion engine is low, it is expected that the startability of the internal combustion engine is low and the fluctuation of the air flow rate becomes large. In this regard, in the second invention, when the water temperature of the internal combustion engine is lower than the reference temperature, the correction according to the air flow rate can be limited. As a result, it is possible to limit the correction of the throttle opening in accordance with the air flow rate having a large fluctuation, and to suppress the fluttering of the throttle valve.

It is a schematic diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a flowchart for demonstrating the control routine which a control apparatus performs in Embodiment 1 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10 mounted on a vehicle. The number of cylinders and the cylinder arrangement of the internal combustion engine 10 are not particularly limited. Each cylinder of the internal combustion engine 10 is provided with a piston 12. An intake passage 14 and an exhaust passage 16 communicate with each cylinder.

  A throttle valve 20 is provided in the intake passage 14. The throttle valve 20 is an electronically controlled valve that is driven by a throttle motor 22. A throttle position sensor 24 for detecting the opening of the throttle valve 20 (hereinafter referred to as “throttle opening”) is provided in the vicinity of the throttle valve 20. An air flow meter 26 that detects the amount of intake air is disposed upstream of the throttle valve 20 in the intake passage 14.

  A crank angle sensor 30 for detecting the rotation angle of the crankshaft 28 is installed in the vicinity of the crankshaft 28 of the internal combustion engine 10. According to the output of the crank angle sensor 30, the rotational position of the crankshaft 28, the engine speed NE, and the like can be detected. An accelerator position sensor 32 for detecting the accelerator opening is provided in the vicinity of the accelerator pedal.

  This system includes an ECU (Electronic Control Unit) 40. The ECU 40 is electrically connected to various sensors such as the throttle position sensor 24, crank angle sensor 30, and accelerator position sensor 32, and various actuators such as the throttle motor 22 described above.

  In this system, the control executed by the ECU 40 as the control device includes calculation of the throttle opening and control of the throttle valve 20 in accordance with the calculated opening. In calculating the throttle opening, first, a plurality of required torques are calculated. The required torque includes a required torque calculated based on the accelerator opening, an auxiliary machine drive required torque required to drive the auxiliary machines, an ABS (anti-lock brake system) required torque, a VSC (Vehicle) Stability control) required torque.

  The ECU 40 calculates the target torque by collecting and arbitrating the plurality of required torques. Further, the ECU 40 calculates a target throttle opening in order to realize the target torque.

  Specifically, in calculating the target throttle opening, first, the target torque is converted into the target intake air amount according to a predetermined map or function. Next, the target intake air amount is compensated for response delay, and the target throttle opening is calculated. The response delay compensation includes air response delay compensation due to intake valve response delay and intake passage volume (surge tank and intake manifold volume), and throttle valve response delay compensation. The compensation amount for compensating for the response delay of air is a value corresponding to the engine speed. The ECU 40 stores the relationship between the air response delay compensation amount and the engine speed as a map. When calculating the air response delay compensation amount, the engine speed is input, and a value corresponding to the engine speed is calculated. The

  The throttle opening in which the air response delay compensation and the throttle valve response delay compensation have been performed is corrected by a correction value corresponding to the air flow velocity. Here, the ECU 40 stores the relationship among the rotation rate, the load factor, and the air flow rate as a map, and calculates the air flow rate from the map. A correction value is calculated according to the calculated air flow velocity calculated value and the actual measured flow velocity value (actual flow velocity), and is reflected in the throttle opening.

  During normal operation of the internal combustion engine 10, the ECU 40 calculates the throttle opening (hereinafter referred to as “normal throttle opening TAISCRQ”) by the above-described method, and controls the throttle valve 20 according to this.

  On the other hand, when the engine speed and the air flow rate at the time of starting the internal combustion engine 10 are unstable, the engine speed fluctuates greatly. For this reason, if the throttle opening with the response delay compensation of air is calculated by the above-described method in an unstable state at the start of the internal combustion engine 10 and the control corresponding to this is performed, the throttle valve 20 can be operated for a short time. And the throttle valve 20 may flutter. Therefore, in the system of the present embodiment, the response delay compensation of air is limited when the internal combustion engine 10 is started.

  Further, for example, when the start is performed in a low temperature environment and the friction is large, if the correction is performed according to the air flow velocity, the change in the throttle opening is further increased and the flutter of the throttle valve 20 is increased. Therefore, when starting at a low temperature, the flow rate correction is further limited.

  Specifically, during normal operation, the air response delay compensation amount is obtained according to the engine speed. However, since the engine speed fluctuates greatly at the start, the air response compensation amount is limited to a fixed value. The fixed value is an appropriate value obtained by experiments and the like in consideration of the average engine speed at the time of starting, etc., and is stored as a fixed value in the ECU 40 and used for calculation of the throttle opening at the time of starting.

  Further, during normal operation, the correction value corresponding to the air flow rate is a value set according to the difference between the actual air flow rate and the flow rate calculated by the map. However, since the fluctuation of the air flow rate is large at the time of cold start, the flow velocity correction value is limited as a fixed value. The fixed value is an appropriate value obtained by an experiment or the like in consideration of an average air flow rate change at the time of low temperature start, and is stored as a fixed value in the ECU 40 and used for calculation of the throttle opening at the start.

  In the system according to the present embodiment, a normal throttle is determined based on the throttle opening (hereinafter referred to as “restricted throttle opening TASTA”) in which the response compensation amount at the start and the flow velocity correction are limited. The switching to the opening is made when the normal throttle opening TAISCRQ calculated by the normal operation method becomes equal to or greater than the limit throttle opening TASTA.

  FIG. 2 is a flowchart for illustrating a control routine executed by the ECU in the present invention. The routine of FIG. 2 is a routine that is periodically and repeatedly executed. In this routine, first, the engine speed NE is detected (S102). The engine speed NE is detected by the ECU 40 using the output of the crank angle sensor 30 installed in the vicinity of the crankshaft as input information. Next, the actual flow rate is detected (S104). The actual flow velocity is detected by the ECU 40 using the output of the air flow meter 26 as input information.

  Next, the normal throttle opening degree TAISCRQ is calculated (S106). The normal throttle opening degree TAISCRQ calculated here is a value subjected to normal response compensation and flow rate correction. Specifically, the target intake air amount with respect to the target torque set according to the accelerator opening detected as described above, the air response delay compensation amount according to the engine speed NE, and the throttle valve response delay compensation The amount and the flow velocity correction value corresponding to the actual flow velocity are calculated according to the maps, and the throttle opening degree TAISCRQ is calculated accordingly.

  Next, it is determined whether or not the flag F is ON (S108). The flag F is a flag that is turned on when a predetermined condition is satisfied in the processing that will be described later in this routine, and is reset and turned off each time the internal combustion engine 10 is stopped.

  If it is not determined in step S108 that the flag F is ON, it is next determined whether or not the internal combustion engine 10 is currently being started and the engine speed NE is stable (S110). Specifically, here, whether or not the engine speed NE is stable is set in advance, such as whether or not the difference between the previous engine speed NE and the currently detected engine speed NE is within a predetermined value. Judgment is made based on whether or not the specified condition is satisfied.

  In step S110, when the engine speed NE is not stable after the internal combustion engine 10 is started, the air response delay compensation amount is first limited (S112). Specifically, the air response delay compensation amount used in the calculation of the throttle opening is a fixed value stored in advance in the ECU 40.

  Next, the water temperature is detected (S114). Here, the water temperature is detected by the ECU 40 using the output of a water temperature sensor (not shown) set near the internal combustion engine 10 as input information. Next, it is determined whether or not the water temperature is equal to or higher than a reference temperature (S116). Here, the reference temperature is a value set in advance as a reference value for determining whether or not the internal combustion engine 10 is at a low temperature and stored in the ECU 40.

  In step S114, when it is not recognized that the temperature is equal to or higher than the reference temperature, the flow velocity correction is limited (S118). Specifically, the flow velocity correction value is a fixed value of the flow velocity correction value at the time of low temperature start stored in the ECU 40 in advance.

  Next, the limited throttle opening is calculated (S120). Specifically, the limited throttle opening degree TASTA is calculated in the same manner as the normal throttle opening degree TAISCRQ. However, the air response delay compensation amount is not a value corresponding to the engine speed NE but a fixed value. Further, as the flow velocity correction value, when the establishment of the water temperature ≧ the reference temperature is recognized in step S116, the flow velocity correction value obtained according to the detected actual flow velocity is used, and the establishment of the water temperature ≧ the reference temperature is recognized. If not, the flow velocity correction value is fixed in advance stored in the ECU 40.

  Next, it is determined whether or not the normal throttle opening degree TAISCRQ calculated in step S106 is greater than or equal to the limited throttle opening degree TASTA calculated in step S120 (S122). Here, when the establishment of TAISCRQ ≧ TASTA is not recognized, the throttle opening is set to the opening TASTA limited in response compensation and flow velocity compensation depending on the case (S124). Thereafter, the flag F is turned off (S126), and the current process is terminated.

  On the other hand, if it is determined in step S108 that the flag F = ON, if the engine speed NE is stabilized after starting in step S110, or if TAISCRQ ≧ TASTA is confirmed in step S122. If this is the case, the throttle opening is set to the normal throttle opening TAISCRQ (S128). The normal throttle opening degree TAISCRQ is a value calculated in step S106, and is an opening degree after normal response delay compensation, flow velocity correction, and the like.

  Thereafter, the flag F is set to ON (S130), and the current process ends. After the flag F = ON for the first time in step S130, the throttle opening calculated in this routine is switched from the limited throttle opening TASTA to the normal throttle opening TAISCRQ until the internal combustion engine 10 is stopped. The opening degree is the air response delay compensation according to the engine speed NE and the flow velocity correction according to the actual flow velocity.

  As described above, according to the present embodiment, it is possible to limit the air response delay compensation when the engine speed at the time of starting is unstable, and further limit the flow velocity correction at low temperatures. . Accordingly, it is possible to prevent the throttle valve from fluttering due to fluctuations in engine speed and flow speed fluctuations at the time of starting.

  In this embodiment, the case where a fixed value is used when limiting the response delay of the air at the start has been described. However, the limiting method is not limited to this in the present invention. For example, when calculating the air response delay compensation amount using a map that uses valve timing as a parameter in addition to the engine speed, the engine speed NE is a fixed value, and the engine speed NE (fixed value) is included in the map. Besides, other necessary parameters can be input to calculate and use the response compensation amount limit value at the time of starting. Further, for example, it may be prohibited without performing response delay compensation.

  Similarly, when obtaining a flow velocity correction value from a map that includes other parameters, the flow velocity correction is performed by inputting only the flow velocity (fixed value) and other parameters to the map. It may be calculated and used. Further, for example, it may be prohibited without correcting the flow velocity. Further, the flow velocity correction may be performed by feedback control.

  Further, in the present embodiment, when it is recognized that the normal throttle opening degree TAISCRQ is equal to or larger than the limit throttle opening degree TASTA, the normal throttle opening degree TAISCRQ is used thereafter. However, in the present invention, the transfer timing to the normal throttle opening degree TAISCRQ is not limited to this. For example, after starting, until the stability of the engine speed NE is recognized, the limited throttle opening TASTA is used, and when the engine speed NE is stable, the engine is switched to the normal throttle opening TAISCRQ. Also good.

  Further, in the present embodiment, it has been described that the above control is performed when the internal combustion engine 10 is being started and the engine speed is unstable. However, the present invention is not limited to this, and the same control may be performed when the engine speed greatly fluctuates in a short time after the internal combustion engine 10 is started.

  In the present embodiment, the case where the normal throttle opening TAISCRQ is calculated according to the response delay compensation amount calculated from the map of the air response delay compensation amount and the engine speed has been described. However, the method of calculating the normal throttle opening degree TAISCRQ in the present invention is not limited to this, and may be calculated according to a map or function including other parameters such as valve timing in addition to the engine speed. it can.

  Similarly, in the present embodiment, a case has been described in which the correction value corresponding to the air flow velocity is obtained according to the air flow velocity calculation value and the actual flow velocity. However, in the present invention, the correction value calculation method is limited to this. is not. For example, the correction value may be calculated according to only the air flow rate calculation value without detecting the actual flow rate.

  In addition, when referring to the number of each element in this embodiment, such as the number, quantity, quantity, range, etc., unless otherwise specified or clearly specified in principle, The invention is not limited to the number mentioned. Further, the structure and the like described in this embodiment are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

  In the present embodiment, the “engine speed detecting means” of the present invention is realized by executing the process of step S102, and the “throttle opening calculating means” is executed by executing the process of step S106. And “response delay compensation means” is realized, and the processing in step S110 is executed, so that “starting state detection means” and “engine speed determination means” are realized, and the processing in step S112 is executed. "Response delay compensation limiting means" is realized.

  In the present embodiment, the “air flow rate detecting means” and the “correcting means” of the present invention are realized by executing the process of step S106, and the “water temperature detection” is executed by executing the process of step S114. "Means" is realized, and the "water temperature determining means" is realized by executing the process of step S116, and the "correction limiting means" is realized by executing the process of step S118.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 14 Intake passage 20 Throttle valve 22 Throttle motor 24 Throttle position sensor 26 Air flow meter 30 Crank angle sensor

Claims (2)

Engine speed detecting means for detecting the engine speed of the internal combustion engine;
Throttle opening calculation means for calculating a target throttle opening for realizing the target torque of the internal combustion engine;
Response delay compensation means for compensating for an air response delay based on an air response delay compensation amount according to the engine speed when calculating the target throttle opening;
A starting state detecting means for detecting a starting state of the internal combustion engine;
Engine speed determining means for determining whether the engine speed is unstable based on the change in the engine speed;
A response delay compensation limiting means for limiting a response delay compensation amount of the air when a starting state of the internal combustion engine is detected and it is determined that the engine speed is unstable;
A control device for an internal combustion engine, comprising: An air flow rate detecting means for detecting an air flow rate introduced into the internal combustion engine;
Correction means for correcting the target throttle opening according to the air flow rate;
Water temperature detecting means for detecting the water temperature of the internal combustion engine;
Water temperature determining means for determining whether or not the water temperature is lower than a reference temperature;
A correction limiting means for limiting the correction of the target throttle opening according to the air flow velocity when it is determined that the water temperature is lower than a reference temperature;
The control apparatus for an internal combustion engine according to claim 1, further comprising:

Images