JP2010281286A - Start control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a start control device for an internal combustion engine capable of securing good engine startability even under a low temperature condition. <P>SOLUTION: An ECU executes motoring in a step S10, and obtains a target suction air amount corresponding to the engine speed of an internal combustion engine when motoring is being performed in a step S13. Thereafter, in a step S14, the ECU compares the detected suction air amount with the target suction air amount obtained in the S13, and determines whether a flow passage resistance in an intake manifold or a surge tank is increased or not. In the case wherein a determination that the flow passage resistance is increased is done, the ECU starts the suction air amount correction for correcting the suction air amount by increasing throttle opening of a throttle valve. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a start control device for an internal combustion engine provided with an EGR device.

  Patent Document 1 discloses an exhaust gas recirculation device (hereinafter referred to as an EGR (Exhaust Gas Recirculation) device) that recirculates part of exhaust gas flowing through an exhaust passage through an exhaust gas recirculation passage that communicates the exhaust passage and the intake passage. )) Is described. An internal combustion engine start control device described in Patent Document 1 is mounted on a hybrid vehicle including an internal combustion engine and an electric motor as a drive source of the vehicle. For example, when the vehicle can run only with the power of the electric motor, the internal combustion engine Is automatically stopped, and thereafter, when the power of the internal combustion engine is required, the internal combustion engine is restarted. Further, even if the vehicle is not mounted on a hybrid vehicle as in Patent Document 1, for example, the internal combustion engine is stopped when the vehicle temporarily stops at a signal or the like, and the internal combustion engine is started when the vehicle starts. Some are restarted.

JP 2008-155813 A

  By the way, in an internal combustion engine equipped with an EGR device, the EGR gas recirculated through the exhaust gas recirculation passage is cooled and condensed by, for example, an EGR cooler or an intercooler, and the condensed water becomes an intake manifold or surge as an intake passage. May stay in tank. If the condensed water stays at a low temperature, the condensed water freezes on the inner wall of the intake manifold and surge tank, and as a result, the flow path resistance increases in the intake manifold and surge tank. Resulting in.

  Even if the flow path resistance increases due to the freezing of the condensed water, if the internal combustion engine is in steady operation, a predetermined intake air amount correction control is performed and the operation of the internal combustion engine is continued. However, at the time of starting, the internal combustion engine cannot take in a sufficient amount of air, which causes a problem that startability deteriorates. In particular, in an internal combustion engine that is frequently stopped and started as described in Patent Document 1, the start control of the internal combustion engine described in Patent Document 1 is greatly affected by the deterioration of engine startability. In the apparatus, no countermeasure has been taken against the problem caused by the condensation water freezing as described above, and there is room for improvement.

  The present invention has been made in view of such circumstances, and an object of the present invention is to start an internal combustion engine that can ensure good engine startability even at low temperatures in an internal combustion engine equipped with an EGR device. It is to provide a control device.

  In order to achieve the above object, an invention according to claim 1 is an internal combustion engine start control device including an EGR device that recirculates a part of exhaust gas flowing through an exhaust passage as EGR gas to an intake passage. The reduction of the intake air amount caused by the condensation water contained in the gas freezing on the inner wall of the intake passage is compensated by increasing the throttle opening, and the reduction of the intake air amount is compensated. The gist of the invention is that it includes start control means for starting the engine.

  According to this configuration, even if the condensed water contained in the EGR gas freezes on the inner wall of the intake passage, thereby increasing the flow resistance of the intake passage and reducing the intake air amount, the reduction is throttled. Compensation is performed by increasing the opening degree, and the engine is started under the compensated condition. Therefore, good engine startability can be ensured even at low temperatures.

  According to a second aspect of the present invention, in the first aspect of the present invention, the intake air amount detecting means for detecting the intake air amount of the internal combustion engine, and the internal combustion engine stopped by a motor when a predetermined start condition is satisfied. Pre-driving means for pre-driving the engine, and permitting means for permitting the correction correction of the throttle opening by the start control means on the condition that the intake air amount of the internal combustion engine is reduced during the pre-driving, The main point is that

  Even if the flow passage resistance of the intake passage increases due to freezing in the intake passage during steady operation, the frozen material melts while the internal combustion engine is stopped, and the flow of the intake passage is Road resistance may decrease. Therefore, if the increase in the throttle opening by the start control means is performed based on the intake air amount during steady operation, and the flow path resistance is reduced at the subsequent engine start, There is concern that the engine speed will increase.

  In this respect, in the above-described invention, the permitting means permits the increase correction of the throttle opening on the condition that the intake air amount is reduced during the preliminary driving of the internal combustion engine. The engine can be started immediately after correction. Therefore, the engine can be started with an appropriate intake air amount.

  According to a third aspect of the present invention, in the second aspect of the present invention, the storage unit stores a map that defines a target intake air amount based on the engine speed, and the permission unit is a reserve for the internal combustion engine. On the condition that the intake air amount at the time of driving is smaller than the target intake air amount based on the engine rotational speed at the time of preliminary driving, the start control means permits the throttle opening increase correction, and the start control means The gist is to increase the throttle opening so that the intake air amount of the internal combustion engine approaches the target intake air amount.

  In this invention, the start control means can correct the throttle opening to increase and start the internal combustion engine after the intake air amount of the internal combustion engine is brought close to the target intake air amount, thereby ensuring good engine startability. Will be able to.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the start control means is configured such that the throttle according to a difference between the intake air amount during the preliminary driving of the internal combustion engine and the target intake air amount. The gist is to perform an increase correction of the opening.

  In the present invention, the air flowing in through the throttle valve can be increased as the reduction amount of the intake air amount of the internal combustion engine is larger than the target intake air amount during the preliminary drive. For this reason, when the internal combustion engine is started, the intake air amount of the internal combustion engine can be kept from being excessive or insufficient with respect to the target intake air amount, and better engine startability can be secured.

  According to a fifth aspect of the present invention, in the first aspect of the invention, the EGR device includes an EGR valve that varies an amount of the EGR gas that is recirculated to the intake passage, and supplies fuel to the internal combustion engine. Fuel cut control means for executing fuel cut control to be interrupted, valve control means for forcibly opening and closing the EGR valve during execution of fuel cut control by the fuel cut control means, and the above-mentioned when the EGR valve is opened and closed And a permitting means for permitting an increase correction of the throttle opening by the start control means on the condition that the pressure transition in the intake passage is different from a preset pressure transition for determination. .

  In the present invention, it is possible to decide whether or not to perform the increase correction of the throttle opening based on the pressure transition of the intake passage that changes in accordance with the magnitude of the flow passage resistance of the intake passage, and to ensure good engine startability. .

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the permission unit may be configured such that the EGR valve is closed after the forced close command is output to the EGR valve or the EGR valve is closed. On the condition that the pressure transition in the intake passage after the EGR valve is opened after the forced valve opening command is output is different from the pressure transition for determination, the throttle opening degree of the start control means The gist is to allow increase correction.

  Here, when the EGR valve transitions from the open state to the closed state or from the closed state to the open state, the pressure change in the intake passage is large, and when the condensed water is frozen or not The difference in pressure change between the two is also remarkable. Therefore, in the present invention, by comparing the pressure transition in the intake passage during the transition of the EGR valve with the pressure transition for determination, it is determined whether or not the increase correction of the throttle opening is permitted. More appropriate start-up can be performed according to the road resistance.

  According to a seventh aspect of the present invention, in the sixth aspect of the present invention, during the time when the EGR valve is closed after the forced valve closing command is output to the EGR valve, or the EGR valve has a forced valve opening command. A calculating unit that calculates a pressure change amount per unit time based on a pressure transition of the intake passage while the EGR valve is opened after being output; and the permission unit is calculated by the calculating unit The gist is to allow the start control means to correct the increase in the throttle opening on the condition that the pressure change amount is different from the pressure change amount obtained from the determination pressure transition.

  Here, the period in which the valve opening state of the EGR valve is in a transitional state changes depending on the operating state of the internal combustion engine. Therefore, based on the pressure value in the intake passage a predetermined time after the valve closing command or valve opening command is output to the EGR valve, it is determined whether or not the permission means permits the throttle opening increase correction. In this case, depending on the operating condition of the internal combustion engine, it is determined whether or not to permit the increase correction of the throttle opening based on the pressure value in the intake passage after the EGR valve is closed or opened. It will be. However, in such a case, the difference between when the condensate freezes and when it does not occur hardly appears, so the permission means can accurately make a determination according to the magnitude of the flow path resistance of the intake passage. There is concern about disappearing.

  In this regard, in the above invention, the amount of pressure change in the intake passage per unit time from the time when the forced valve closing command or forced valve opening command is output is calculated, and the amount of pressure change can be obtained from the pressure transition for determination. By comparing with the pressure change amount, the permission means determines whether or not to permit the increase correction of the throttle opening by the start control means. Further, since it is not determined whether to permit the increase correction of the throttle opening based on a pressure value for a certain arbitrary time, an appropriate start according to the state of the intake passage regardless of the operating state of the internal combustion engine. It can be performed.

  The invention according to claim 8 is an idling stop vehicle according to claim 1, wherein only the internal combustion engine is used as a travel drive source, and the idling stop vehicle is started by cranking the temporarily stopped internal combustion engine. And an intake air amount detection means for detecting the intake air amount of the internal combustion engine, and a throttle opening correction means for correcting the throttle opening according to the detection result of the intake air amount detection means during steady operation. The start control means executes the increase correction of the throttle opening when the throttle opening correction means performs the increase correction of the throttle opening to compensate for the decrease in the intake air amount during the steady operation. And

  In the idling stop vehicle, if the cranking is performed for a long time when starting the internal combustion engine, the driver feels uncomfortable, so the cranking time is limited. If cranking cannot be performed for a long time, it is difficult to secure a flow rate necessary for the intake air amount detection means to detect the flow rate during cranking. Therefore, when the intake air amount detection means detects the intake air amount at the time of cranking and determines whether or not to increase the throttle opening based on the detected intake air amount, the flow passage resistance of the actual intake passage is determined. There is a risk that the corresponding start-up cannot be performed accurately.

  In this regard, in the above invention, the start control means corrects the increase in the throttle opening according to whether or not the throttle opening correction means has corrected the increase in the throttle opening during steady operation where a sufficient flow rate can be secured in the intake passage. Decide whether to do it. Therefore, the start control means determines whether or not to perform the increase correction of the throttle opening according to the correction mode of the throttle opening correction means during the steady operation, and therefore regardless of the flow rate of the air flowing through the intake passage at the time of cranking. Thus, it is possible to perform an appropriate start according to the flow path resistance of the intake passage.

1 is a schematic configuration diagram showing a vehicle on which an internal combustion engine to which the internal combustion engine is applied in a first embodiment that embodies an internal combustion engine start control device according to the present invention; The schematic block diagram which shows the internal combustion engine of the same embodiment, and its periphery structure. The flowchart which shows the process sequence of restart control in the embodiment. The graph which shows the relationship between the difference of the intake air amount with respect to target intake air amount, and the correction coefficient which correct | amends throttle opening. The timing chart which shows the change aspect of intake air amount and throttle opening when restart control is performed. The flowchart which shows the process sequence of restart control in 2nd Embodiment. The graph which shows the pressure transition of the intake pipe pressure from the time of outputting valve closing instruction | command in the same embodiment, and the pressure transition for determination. The graph which shows the relationship between the difference of the intake pipe pressure value with respect to the intake pipe pressure value for determination, and the correction coefficient which correct | amends throttle opening. The graph which shows the pressure transition of the intake pipe pressure from the time of outputting valve closing instruction | command in 3rd Embodiment, and the pressure transition for determination. 4 is a graph showing the relationship between the difference in the amount of change in the intake pipe pressure with respect to the amount of change in the pressure for determination in the embodiment and the correction coefficient for correcting the throttle opening. In 4th Embodiment, the schematic block diagram which shows a part of vehicle by which the internal combustion engine to which the starting control apparatus of 4th Embodiment is applied is mounted. (A) is a flowchart which shows the process sequence of the intake air amount correction | amendment control performed during a steady driving | operation of an internal combustion engine, (b) is a flowchart which shows the process sequence of restart control.

(First embodiment)
Hereinafter, a first embodiment of a start control device for an internal combustion engine according to the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the vehicle 11 is a hybrid vehicle having an internal combustion engine 12 and an electric motor 13 as drive sources. The power output by the internal combustion engine 12 and the electric motor 13 is transmitted to the drive wheels 15 via the transmission 14.

  The power output from the internal combustion engine 12 is distributed to power transmitted to the drive wheels 15 and power transmitted to the motor generator 18 by a power distribution mechanism 16 connected to the engine 12. The electric power generated by the motor generator 18 based on the power transmitted from the internal combustion engine 12 in this way is supplied to the battery 20 via the power converter 19. When the internal combustion engine 12 is started, the motor generator 18 functions as a starter by supplying electric power from the battery 20.

  The electric motor 13 outputs power by being supplied with electric power stored in a battery 20 that is a power storage device. The electric motor 13 generates electric power using the rotational force received from the drive wheels 15 when the vehicle 11 is decelerated or braked. The generated power is output to the power converter 19 and supplied to the battery 20 via the power converter 19.

  The power conversion unit 19 includes an inverter, a converter, and the like. The power conversion unit 19 converts AC power input from the motor 13 and the motor generator 18 into DC power and converts the voltage into a voltage level of the battery 20 to convert the battery 20. Output to. Further, the DC power supplied from the battery 20 is converted into AC power and boosted, and the same power is supplied to the motor 13 or the motor generator 18.

  The battery 20 is a chargeable / dischargeable power storage device, and is composed of, for example, a secondary battery such as nickel metal hydride or lithium ion. The battery 20 supplies power to the motor 13 and the motor generator 18 via the power converter 19 and is charged from the motor 13 and the motor generator 18 via the power converter 19. Specifically, the electric power generated by the motor 13 and the motor generator 18 and output to the power converter 19 is charged. A battery sensor 20 a for detecting a state of charge (SOC) of the battery 20 is attached to the battery 20.

Next, the internal combustion engine 12 and its peripheral configuration will be described with reference to FIG.
As shown in FIG. 2, a piston 21 is accommodated in the cylinder of the internal combustion engine 12 so as to be able to reciprocate. A combustion chamber 22 is defined by the top surface of the piston 21 and the inner peripheral surface of the cylinder. ing. An intake passage 23 that supplies intake air to the combustion chamber 22 and an exhaust passage 24 that exhausts exhaust gas from the combustion chamber 22 are connected to the combustion chamber 22.

  The combustion chamber 22 is provided with a fuel injection valve 25 that injects fuel into the combustion chamber 22 and an ignition plug 26 that ignites a mixture of air and fuel in the combustion chamber 22. The piston 21 is connected to a crankshaft 27 that is an output shaft of the internal combustion engine 12. The crankshaft 27 rotates as the piston 21 reciprocates due to combustion of the air-fuel mixture in the combustion chamber 22. As described above, the rotation of the crankshaft 27 is transmitted to the drive wheels 15 (see FIG. 1) of the vehicle 11 via the transmission 14 (see FIG. 1).

  The intake passage 23 is provided with a throttle valve 28 for adjusting the amount of intake air (intake air amount) flowing through the passage 23 and a throttle actuator 29 for adjusting the opening degree of the valve 28. Further, a throttle valve opening sensor 30 that outputs a signal corresponding to the opening degree of the valve 28 is attached to the throttle valve 28. An intake pipe 23a that is a part of the intake passage 23 and has a downstream portion branched for each cylinder is provided downstream of the throttle valve 28.

  The intake pipe 23a is integrally formed with a surge tank 23b which is a calming tank for suppressing intake pulsation. The downstream portion of the intake pipe 23a is connected to the combustion chamber 22 of each cylinder via an intake port. The intake pipe 23a is provided with an intake air temperature sensor Tu for detecting the wall surface temperature downstream of the surge tank 23b.

The internal combustion engine 12 is provided with an exhaust gas recirculation (hereinafter referred to as “EGR”) device 32 that recirculates part of the exhaust gas flowing through the exhaust passage 24 to the intake passage 23.
The EGR device 32 includes an EGR passage 33 that communicates the exhaust passage 24 and the intake passage 23, and an EGR valve 34 that adjusts the amount of exhaust gas flowing through the EGR passage 33. The EGR passage 33 branches from the middle of the exhaust passage 24 and is connected to the surge tank 23b. The EGR valve 34 is provided with an EGR actuator 35 that adjusts the opening of the valve 34 and an EGR valve opening sensor 36 that outputs a signal corresponding to the opening of the EGR valve 34. When the EGR valve 34 is opened through driving of the EGR actuator 35, a part of the exhaust gas in the exhaust passage 24 is introduced into the surge tank 23 b and recirculated to the combustion chamber 22.

  The EGR passage 33 is provided with an EGR cooler 37 that cools the exhaust gas flowing through the EGR passage 33. The EGR cooler 37 cools the exhaust gas by exchanging heat between the exhaust gas flowing through the EGR passage 33 and the engine cooling water. In addition to such a water-cooled EGR cooler, an air-cooled EGR cooler may be adopted.

  In addition to the various sensors described above, the internal combustion engine 12 and the vehicle 11 are further provided with various sensors. As such sensors, for example, a rotational speed sensor 38 for detecting the engine rotational speed, an engine water temperature sensor 39 for detecting the temperature of the engine cooling water, and the pressure of the intake air downstream of the throttle valve 28 in the intake passage 23 ( Hereinafter, an intake pipe pressure sensor 41 for detecting “intake pipe pressure”), an air flow meter 31 as intake air quantity detection means for detecting the intake air quantity GA of the internal combustion engine 12, and the like are provided.

  The output signals of these sensors are input to an electronic control unit (hereinafter referred to as “ECU”) 40. The ECU 40 includes a central processing unit (CPU) that executes various arithmetic processes, a memory that stores various control programs, arithmetic maps, data calculated when the control is executed, an A / D converter, an input / output interface, and the like (All are not shown). Further, the ECU 40 as the storage means stores a map that defines the target intake air amount Gb according to the rotational speed of the internal combustion engine 12. And ECU40 grasps | ascertains the state of various apparatuses, such as the driving state of the vehicle 11, the driving | running state of the internal combustion engine 12, based on the input signal, and performs various controls. For example, the ECU 40 controls the fuel injection control for injecting an appropriate amount of fuel from the fuel injection valve 25 at an appropriate timing, the ignition timing control for adjusting the ignition timing of the ignition plug 26, and the opening of the throttle valve 28. Throttle control for driving the throttle actuator 29 is appropriately executed for adjustment. In addition, the ECU 40 detects the state of charge (SOC) of the battery 20 based on a signal from the battery sensor 20a, and appropriately executes charge / discharge control of the battery 20 that keeps the SOC within a predetermined range.

  Further, the ECU 40 executes EGR control for recirculating a part of the exhaust gas to the combustion chamber 22 through the EGR passage 33 in order to reduce the emission amount of nitrogen oxides (NOx) and improve the fuel consumption. . The EGR control is executed when a predetermined condition is satisfied during operation of the internal combustion engine 12. In the EGR control, the operating state of the internal combustion engine is grasped based on the engine rotation speed detected by the rotation speed sensor 38, the intake air amount GA detected by the air flow meter 31, and the like. Then, the opening degree of the EGR valve 34 is adjusted through driving of the EGR actuator 35 so that the exhaust amount suitable for the grasped engine operating state is recirculated to the combustion chamber 22 through the EGR passage 33. The exhaust gas that has flowed into the EGR passage 33 by the EGR control is cooled in the above-described EGR cooler 37 and then recirculated to the combustion chamber 22.

  Further, the ECU 40 may execute fuel cut control for interrupting fuel injection from the fuel injection valve 25 while the vehicle 11 is traveling, and may perform control for forcibly opening and closing the EGR valve 34. For example, as such control, there is abnormality diagnosis control that is performed to diagnose the presence or absence of abnormality of the EGR device 32 while the vehicle 11 is traveling at a reduced speed. In the abnormality diagnosis control, a pressure change amount of the intake pipe pressure accompanying opening / closing of the EGR valve 34 is obtained, and the presence / absence of an abnormality of the EGR device 32 is diagnosed based on the pressure change amount. The fuel cut control means is constituted by the ECU 40. Further, the valve control means is constituted by an ECU 40 and an EGR actuator 35.

  Further, the ECU 40 calculates the output required for both the internal combustion engine 12 and the electric motor 13 in consideration of the required driving force of the vehicle 11, the required load of the internal combustion engine 12, the SOC of the battery 20, and the like. The internal combustion engine 12 and the electric motor 13 are controlled so that the output to be obtained is obtained.

  Specifically, when the ECU 40 determines that the required driving force of the vehicle 11 is obtained only by the power of the electric motor 13 and determines that the SOC of the battery 20 is within a predetermined range, the “stop” of the internal combustion engine 12 is performed. It is determined that “condition” is satisfied. At this time, the ECU 40 executes the automatic stop control of the internal combustion engine 12 to place the internal combustion engine 12 in a stopped state and cause the vehicle 11 to travel using only the power of the electric motor 13.

  On the other hand, if the ECU 40 determines that the power of the internal combustion engine 12 is necessary to obtain the required driving force of the vehicle 11, or if it is determined that the SOC of the battery 20 is below a predetermined value, the internal combustion engine Therefore, it is determined that the “start condition” of the internal combustion engine 12 is satisfied. At this time, the ECU 40 performs a restart control for restarting the internal combustion engine 12.

  When the internal combustion engine 12 is started, the vehicle 11 is in a traveling state by the power of both the internal combustion engine 12 and the electric motor 13. That is, the vehicle 11 of the present embodiment is configured so that the internal combustion engine 12 is intermittently operated by repeatedly stopping and restarting the internal combustion engine 12.

Next, with reference to FIG. 3, the processing procedure of the restart control will be described.
First, when restart control is started, it progresses to S10 and a motoring process is performed. In this motoring process, the power of the motor generator 18 is transmitted to the internal combustion engine 12 so that the internal combustion engine 12 is preliminarily driven. Then, the ECU 40 proceeds to S11 and determines whether or not the intake air temperature is lower than 0 ° C., that is, whether or not the outside air temperature is below freezing point, based on the detection result of the intake air temperature sensor Tu. At this time, if the determination is negative, it is unlikely that the condensed water will freeze, so the routine proceeds to S12 and normal engine start is executed. When the normal engine start is executed, predetermined fuel injection control and predetermined ignition timing control are executed with the throttle opening set to the closed side. As a result, the internal combustion engine 12 comes to operate autonomously.

  On the other hand, if the ECU 40 makes a positive determination in S11, the process proceeds to S13. In S13, the ECU 40 reads a target intake air amount Gb corresponding to the rotational speed of the internal combustion engine 12 during motoring from the map. Thereafter, the process proceeds to S14. In S14, the target intake air amount Gb read from the map is compared with the actual intake air amount obtained from the detection result of the air flow meter 31. When the intake air amount and the target intake air amount Gb are equal, the ECU 40 determines that the condensed water is not frozen and the flow path resistance of the intake pipe 23a and the surge tank 23b is small, and the process proceeds to S12. On the other hand, when the intake air amount is smaller than the target intake air amount Gb, the ECU 40 determines that there is a large amount of condensed water frozen and the flow path resistance of the intake pipe 23a and the surge tank 23b is increased, and the process proceeds to S15. move on.

  In S15, the difference α between the target intake air amount Gb and the intake air amount is calculated, and after increasing the throttle opening degree TA based on the calculation result, the engine is started. Specifically, the ECU 40 reads the correction coefficient corresponding to the difference α between the target intake air amount Gb and the intake air amount GA with reference to the map shown in FIG. The target throttle opening degree Ta is calculated by multiplying the correction coefficient. As shown in FIG. 4, the relationship between the difference α of the intake air amount with respect to the target intake air amount Gb and the correction coefficient is a proportional relationship, and the difference α between the target intake air amount Gb and the intake air amount is In the case of 0, the correction coefficient is 1, and the correction coefficient increases as the difference α between the target intake air amount Gb and the intake air amount increases. In S15, the ECU 40 performs control so that the throttle opening of the throttle valve 28 is increased stepwise, and finally opens to the target throttle opening Ta. Thereafter, the ECU 40 executes fuel injection control and ignition timing control of the spark plug 26 to bring the internal combustion engine 12 into an autonomous operation state. Note that in the fuel injection control performed by the ECU 40 in S12 and S14, the fuel injection amount is increased as compared with the steady operation of the internal combustion engine 12. The processes of S10, S14, and S15 correspond to the processes of the preliminary drive unit, the permission unit, and the start control unit, respectively. The ECU 40 corresponds to a preliminary drive unit that performs preliminary drive of the internal combustion engine 12 by motoring and a start control unit that starts the internal combustion engine 12.

Next, transition of the throttle opening and the intake air amount when the ECU 40 executes the restart control will be described with reference to the timing chart shown in FIG.
In FIG. 5, at time t1, motoring of the internal combustion engine 12 is started by the motor generator 18, and the internal combustion engine 12 starts to suck air. Here, since the throttle opening degree TA of the throttle valve 28 is set to the closed side, if the condensed water is frozen, the intake air amount of the internal combustion engine 12 does not reach the target intake air amount Gb, but the target intake air amount Gb. It changes in a state where it is smaller than the intake air amount Gb. However, after that, at time t2, the ECU 40 starts correction for increasing the throttle opening, so that the throttle opening TA of the throttle valve 28 gradually increases after time t2. At time t3, the throttle opening degree TA of the throttle valve 28 reaches the target throttle opening degree Ta, and thereafter, the throttle valve 28 is held open to the target throttle opening degree Ta. Therefore, after time t3, the intake air amount is held at the target intake air amount Gb, and when the fuel injection control and the ignition control of the spark plug 26 are executed in this state, the internal combustion engine 12 comes to operate autonomously.

Next, the control content of the start control device for the internal combustion engine in the present embodiment will be described.
In the vehicle 11, EGR control for recirculating exhaust gas to the combustion chamber 22 may be executed during traveling in order to reduce the combustion temperature in the combustion chamber 22. Therefore, in the vehicle 11, it is possible to improve the efficiency of filling the exhaust gas into the combustion chamber 22 and to reduce the combustion temperature in the combustion chamber 22, thereby more effectively reducing NOx and improving fuel consumption. Will be able to.

  In the vehicle 11, when exhaust gas is recirculated to the combustion chamber 22, condensed water may be generated by cooling the exhaust gas by the EGR cooler 37. In this situation, when the vehicle 11 travels from the power of both the internal combustion engine 12 and the electric motor 13 and shifts to a state where the operation of the internal combustion engine 12 is stopped and the motor 13 travels only by the power, the condensed water is taken in. It stays in the pipe 23a and the surge tank 23b. In particular, the vehicle 11 according to the present embodiment frequently stops and starts the internal combustion engine 12, so the internal combustion engine 12 has many opportunities to be stopped, and the condensed water stays well. When the vehicle 11 according to this embodiment is below freezing, the condensed water staying in the intake pipe 23a and the surge tank 23b is frozen on the inner wall of the intake pipe 23a and the surge tank 23b. As a result, the flow path resistance increases in the intake pipe 23a and the surge tank 23b. If the restart control of the internal combustion engine 12 is executed in this state, the intake air amount of the internal combustion engine 12 may be insufficient and the startability of the internal combustion engine 12 may be deteriorated. However, in this embodiment, the throttle opening is increased. By performing the correction, the amount of air flowing in through the throttle valve 28 is increased, and the decrease in the intake air amount of the internal combustion engine 12 is compensated. For this reason, the intake air amount of the internal combustion engine 12 at the time of restart is not insufficient, and the internal combustion engine 12 starts well even when it is below freezing.

According to this embodiment, the following effects can be obtained.
(1) When the internal combustion engine 12 is below freezing, the condensed water in the intake pipe 23a and the surge tank 23b is frozen and the flow path resistance increases in the intake pipe 23a and the surge tank 23b. When the engine 12 is started, the throttle opening of the throttle valve 28 is corrected to be increased to compensate for a decrease in the intake air amount of the internal combustion engine 12. Therefore, even when the temperature is below freezing, the amount of intake air required at the time of starting can be secured, and the good startability of the internal combustion engine 12 can be secured.

  (2) During steady operation of the internal combustion engine 12, even if there is frozen material in the surge tank 23b or the intake pipe 23a and the flow path resistance increases, the outside air temperature rises and freezes while the internal combustion engine 12 is stopped. When the object melts, the flow path resistance of the surge tank 23b and the intake pipe 23a may decrease at the start. For this reason, if a method of correcting the opening of the throttle valve 28 at the time of restart based on the learning value obtained by the intake air amount correction control performed at the time of steady operation is employed, the internal combustion engine 12 is started after the steady operation. If the flow path resistance is low, the intake air amount of the internal combustion engine 12 becomes excessive, and the rotational speed of the internal combustion engine 12 may rise. On the other hand, in the present embodiment, the increase in throttle opening is corrected on the condition that the intake air amount of the internal combustion engine 12 during motoring immediately before the internal combustion engine 12 is started is smaller than the target intake air amount. Therefore, the engine can be started immediately after the increase in the throttle opening is corrected. Therefore, the engine can be started with the intake air amount being appropriate.

  (3) When the ECU 40 executes the intake air amount correction start in S14, the correction coefficient according to the difference α between the intake air amount of the internal combustion engine 12 during motoring and the target intake air amount Gb stored in the map And the target throttle opening Ta is calculated by multiplying the reference throttle opening by the correction coefficient. Then, the throttle opening degree TA is increased to the target throttle opening degree Ta to compensate for the reduction of the intake air amount. Accordingly, the larger the difference α of the actual intake air amount of the internal combustion engine 12 with respect to the target intake air amount Gb, the greater the amount of air that can flow through the throttle valve 28, and the intake air of the internal combustion engine 12 at the time of start-up. Since the amount can be in a state where there is no excess or deficiency with respect to the target intake air amount, better engine startability can be secured.

  (4) In the fuel injection control performed at the time of starting, the fuel injection amount is increased from that at the time of steady operation. Therefore, when the amount of intake air decreases at the time of starting, the fuel injected at the time of starting covers the spark plug 26. There are concerns. However, in this embodiment, since the decrease in the intake air amount at the time of starting below the freezing point is compensated, the amount of intake air at the time of starting the internal combustion engine 12 is insufficient, so that the fuel injected at the start becomes excessive and ignition occurs. Covering the plug 26 can be suppressed.

  (5) Even if the condensed water contained in the EGR gas freezes and becomes solid, and therefore the intake air amount of the internal combustion engine 12 at the time of start-up decreases, the increase in throttle opening is corrected to correct the internal combustion engine 12 Since the reduction of the intake air amount is compensated, it is possible to ensure good startability of the internal combustion engine 12 regardless of the phase state of the EGR gas.

  (6) Even when the vehicle 11 is below freezing, the ECU 40 can perform EGR control on the EGR device 32 to recirculate part of the exhaust. Therefore, in the start control device for the internal combustion engine of the present embodiment, compared with the case where the control for interrupting the recirculation of the exhaust gas is performed when the outside air temperature is below the freezing point in order to avoid the freezing of the condensed water of the EGR gas, Opportunities for control can be increased. Therefore, it can contribute to the improvement of the fuel consumption of the internal combustion engine 12.

  (7) Each time the restart control is executed, the ECU 40 determines whether or not the flow path resistance is increased based on the intake air amount when the internal combustion engine 12 is motored. That is, each time restart control is performed, it is determined whether or not the flow path resistance is increased. Therefore, the flow path resistance of the intake pipe 23a or the surge tank 23b may change before the engine is started. The engine can be started according to the actual flow path resistance.

  (8) The ECU 40 executes the automatic stop control of the internal combustion engine 12 when it is determined that the “stop condition” that the operation of the vehicle 11 using only the power of the electric motor 13 is possible is satisfied. According to the present embodiment, since the good restartability of the internal combustion engine 12 is ensured, even if the internal combustion engine 12 is frequently started by performing the intermittent operation of the internal combustion engine 12, the vehicle 11 is in trouble. It can run without.

(Second Embodiment)
Next, a second embodiment of the internal combustion engine start control device according to the present invention will be described with reference to FIGS. In the present embodiment, the restart control process described above is changed and executed in the process shown in FIG. In the first embodiment, the determination process is performed as to whether the flow path resistance of the intake pipe 23a and the surge tank 23b is increased based on the intake air amount of the internal combustion engine 12 during motoring. In the present embodiment, the intake pipe pressure during steady operation is detected, and determination processing is performed as to whether or not the flow path resistance of the intake pipe 23a and the surge tank 23b is increased based on the pressure transition of the intake pipe pressure. Is different. Hereinafter, such differences will be mainly described.

  First, the ECU 40 forcibly activates the EGR valve 34 during the fuel cut control in which the fuel injection from the fuel injection valve 25 is interrupted by executing, for example, abnormality diagnosis control during steady operation. The intake pipe pressure is detected at that time. The ECU 40 is configured to store the detected intake pipe pressure as a pressure transition in association with the time since the start of the abnormality diagnosis control. Note that the intake pipe pressure at an arbitrary time detected by the ECU 40 is an average value calculated by reading a value in a predetermined period immediately before that. Further, the ECU 40 stores in advance the pressure transition for determination that is the same as the pressure transition that can be considered that the flow path resistance in the intake pipe 23a and the surge tank 23b is small. This pressure transition for determination is obtained in advance by calculation or experiment. Here, while the EGR valve 34 is closed after the valve closing command is input to the EGR valve 34, that is, during the transition of the EGR valve 34, the negative pressure state of the intake pipe pressure increases with time. When the intake pipe 23a and the surge tank 23b are frozen, the volume of the intake passage 23 is reduced, so the rate at which the intake pipe pressure becomes negative per unit time increases. For this reason, when there is a frozen object in the intake pipe 23a or the surge tank 23b, the pressure transition of the intake pipe pressure is different from the pressure transition for determination, and the pressure transition of the intake pipe pressure is compared with the pressure transition for determination. For example, it can be determined whether or not there is frozen material in the intake pipe 23a or the surge tank 23b.

Next, with reference to FIG. 6, the process sequence of the restart control which ECU40 performs in this embodiment is demonstrated.
When this control is executed, the ECU 40 executes the processes of S20 and S21, which are the same processes as S10 and S11. If a negative determination is made in S21, the process proceeds to S22, and normal engine start is executed. If an affirmative determination is made in S21, the process proceeds to S23, and the pressure transition of the intake pipe pressure stored in the ECU 40 is read. Thereafter, the process proceeds to S24. In S24, the pressure transition of the read intake pipe pressure is compared with the determination pressure transition stored in the ECU 40, and whether the flow path resistance in the surge tank 23b or the intake pipe 23a is increased. Processing to determine whether or not. Here, the change in the intake pipe pressure is large during the transition of the EGR valve 34 from the open state to the closed state, and the difference in pressure change between when the condensate water freezes and when it does not occur is significant. is there. Therefore, in S24, the intake pipe pressure value H2 at a time T1 when a predetermined time has elapsed from the time when the valve closing command is output to the EGR valve 34 is grasped from the intake pipe pressure transition, and the determination is made based on the grasped intake pipe pressure value H2. Process. That is, at time T1, the intake pipe pressure value H2 that can be grasped from the intake pipe pressure transition is compared with the determination intake pipe pressure value H1 that can be grasped from the determination pressure transition. The time T1 is set to be the time before the EGR valve 34 is closed.

  Therefore, in S24, when the intake pipe pressure value at the time T1 after the valve closing command is output to the EGR valve 34 and the determination intake pipe pressure value are equal, the condensed water is not frozen, It determines with channel resistance being small, and progresses to S22. On the other hand, in S24, the ECU 40 shows that the pressure transition of the intake pipe pressure indicated by the A line in FIG. 7 is different from the pressure transition for determination indicated by the B line in FIG. When the difference β occurs between the value H1 and the value H1, it is determined that the flow path resistance is increased due to the freezing of the condensed water, and the process proceeds to S25. In S24, when there is a difference β between the intake pipe pressure value H2 and the determination intake pipe pressure value H1 at time T1, the ECU 40 determines that the intake pipe pressure value H2 and the determination intake pipe pressure value H1 Is temporarily stored. In S24, the ECU 40 refers to a map stored in advance, and performs an increase correction of the throttle opening degree TA based on the difference β between the intake pipe pressure value H2 and the determination intake pipe pressure value H1. Specifically, the ECU 40 reads the correction coefficient corresponding to the difference β between the intake pipe pressure value H2 and the determination intake pipe pressure value H1 with reference to the map shown in FIG. The target throttle opening degree Ta is calculated by multiplying the correction coefficient determined for the target throttle opening degree Ta. As shown in FIG. 8, the relationship between the difference β between the intake pipe pressure value H2 and the determination intake pipe pressure value H1 at time T1 after the closing command is output to the EGR valve 34, and the correction coefficient is as follows. The relationship between the difference α of the intake air amount GA with respect to the target intake air amount Gb of the first embodiment and the correction coefficient is equal.

  In S25, the throttle opening of the throttle valve 28 is controlled to increase stepwise, and the throttle valve 28 is opened to the target throttle opening Ta. In addition, the ECU 40 executes fuel injection control and ignition timing control of the spark plug 26 to bring the internal combustion engine 12 into a self-sustaining operation state. Note that the processes of S20, S24, and S25 correspond to the processes of the preliminary drive unit, the permission unit, and the start control unit, respectively.

According to this embodiment, in addition to the effects (1) and (4) to (8) described in the first embodiment, the following effects can be obtained.
(9) The ECU 40 opens and closes the EGR valve 34 during execution of fuel cut control for interrupting fuel injection, and stores the pressure transition of the intake pipe 23a at that time. Then, the ECU 40 compares the pressure transition of the intake pipe 23a and the determination intake pipe pressure transition during execution of the restart control, and the condition that the pressure transition of the intake pipe 23a is different from the determination pressure transition. Then, it is determined to perform an increase correction of the throttle opening. Therefore, when the flow path resistance in the intake pipe 23a and the surge tank 23b is increased, the throttle opening is increased, and good engine startability can be ensured.

  (10) The ECU 40 refers to the stored pressure transition in the intake pipe 23a, and the pressure value in the intake pipe 23a at time T1 is more negative than the preset intake pipe pressure value H1 for determination. In addition, it is determined that the flow path resistance has increased. The ECU 40 compares the intake pipe pressure value H2 when the EGR valve 34 transitions from the open state to the closed state with the determination intake pipe pressure value H1 at the same time T1, thereby correcting the increase in the throttle opening. Decide whether to do it. Therefore, a more appropriate engine start can be executed according to the flow path resistance in the intake pipe 23a and the surge tank 23b.

(Third embodiment)
Next, a third embodiment of the internal combustion engine start control device according to the present invention will be described with reference to FIGS. In the present embodiment, the method for determining whether or not the flow path resistance is increased in S24 of the second embodiment is different from that of the second embodiment. explain.

  In this embodiment, when the ECU 40 executes the restart control, in S24, the determination per unit time based on the pressure change amount of the intake pipe pressure per unit time based on the intake pipe pressure transition and the determination pressure transition. Calculate the amount of change in working pressure. Here, the pressure change amount of the intake pipe pressure is calculated based on the pressure transition of the intake pipe 23a from when the valve closing command is output until the EGR valve 34 is closed. Further, the pressure change amount of the determination pressure is calculated based on the determination pressure transition corresponding to the time from when the valve closing command is output until the EGR valve 34 is closed. Here, when there is frozen material in the intake pipe 23a or the surge tank 23b, the volume of the intake passage 23 is reduced. Therefore, the pressure transition of the intake pipe 23a is as shown by line D in FIG. It shifts to the side where the pressure change amount of the intake pipe pressure increases rather than the pressure transition for determination indicated by the C line of 9. Therefore, in S24, the pressure change amount of the intake pipe pressure is compared with the pressure change amount of the determination pressure transition, and when the difference γ between them is smaller than a predetermined value, the ECU 40 does not freeze the condensed water. Then, it is determined that the flow path resistance is small, and the process proceeds to S22. On the other hand, in S24, the ECU 40 compares the pressure change amount of the intake pipe pressure with the pressure change amount of the determination pressure, and determines that the flow path resistance is increased when the difference γ between the two is equal to or greater than a predetermined value. The difference γ between the two is temporarily stored.

  In S25, the correction coefficient is determined from the difference γ between the pressure change amount of the intake pipe pressure and the pressure change amount of the determination pressure with reference to the map stored in the ECU 40. In S25, the target throttle opening degree Ta is calculated by multiplying the correction coefficient determined with respect to the preset reference throttle opening degree. In S25, the throttle opening of the throttle valve 28 is increased stepwise to open the throttle valve 28 to the target throttle opening Ta. In addition, the ECU 40 executes fuel injection control and ignition timing control of the spark plug 26 to place the internal combustion engine 12 in a self-sustaining operation state. The process of S24 corresponds to the process of the calculation unit.

According to this embodiment, in addition to the effects (1) and (4) to (9) described in the first embodiment and the second embodiment, the following effects can be obtained.
(11) Here, the period during which the EGR valve 34 is in a transitional state from when the valve closing command is input to the EGR valve 34 to when the EGR valve 34 is closed varies depending on the operating state of the internal combustion engine. Therefore, when it is determined whether the flow resistance is increased from the pressure value in the intake pipe 23a when the time T1 has elapsed since the valve closing command was input to the EGR valve 34 as in the second embodiment, the internal combustion engine Depending on the operating condition of the engine 12, it is determined whether or not to increase the throttle opening based on the pressure value in the intake pipe 23a after the EGR valve 34 is closed. However, in such a case, it is difficult for the difference between the case where the condensed water is frozen and the case where the condensed water does not occur, so the ECU 40 may not be able to accurately determine the flow path resistance. Concerned. In this regard, the ECU 40 of the present embodiment refers to the stored pressure transition in the intake pipe 23a, and the amount of pressure change in the intake pipe 23a per unit time after the valve closing command is output to the EGR valve 34 is previously determined. When it is different from the set determination pressure change amount, it is determined that the flow path resistance is increased. Therefore, an accurate determination can be made regardless of the operating condition of the internal combustion engine 12.

(Fourth embodiment)
Next, a fourth embodiment that embodies the start control device for an internal combustion engine according to the present invention will be described with reference to FIGS. 11 and 12, focusing on differences from the first to third embodiments. To do. In the present embodiment, the start control device for an internal combustion engine according to the present invention is mounted on a vehicle 11 using only the internal combustion engine 12 as a travel drive source, and based on the intake air amount change during steady operation of the internal combustion engine 12. Thus, the main difference is that the determination processing is performed as to whether or not the channel resistance is increased.

  The vehicle 11 of the present embodiment is an idling stop vehicle. As shown in FIG. 11, the internal combustion engine 12 has a crankshaft 27, which is an engine output shaft thereof, without the power distribution mechanism 16 and the transmission 14. It is connected. The output of the internal combustion engine 12 is transmitted by a transmission 14 and then transmitted to a wheel shaft (not shown). Further, a starter motor 52 that is an electric motor for starting the engine is fixed to the internal combustion engine 12. The starter motor 52 is drivingly connected to the crankshaft 27. That is, the starter motor 52 is configured to be able to transmit a rotational force to the crankshaft 27 via the gear mechanism 53.

  Before starting the internal combustion engine 12, the ECU 40 performs cranking as a preliminary drive that drives the starter motor 52 to rotate the internal combustion engine 12 at a predetermined speed (for example, about 250 rpm). The ECU 40 performs fuel injection control and ignition timing control with the internal combustion engine 12 cranked, thereby causing the internal combustion engine 12 to operate autonomously.

  Further, the ECU 40 stores a map showing the relationship between the rotational speed and load of the internal combustion engine 12 and the target intake air amount Gb. The ECU 40 determines the difference between the actual intake air amount and the target intake air amount Gb corresponding to the rotational speed and load of the internal combustion engine 12 during steady operation of the internal combustion engine 12. Correction control for compensation is executed at a predetermined control cycle. Further, the ECU 40 is configured to temporarily store the learned value obtained by the correction control during the steady operation of the internal combustion engine 12.

Next, the correction control processing procedure will be described with reference to FIG.
First, in S30, the ECU 40 obtains the intake air amount based on the detection result of the air flow meter 31, and proceeds to S31. In S31, the target intake air amount Gb corresponding to the rotational speed and load of the internal combustion engine 12 during steady operation is read from the map, and a correction value is obtained based on the difference between the target intake air amount Gb and the intake air amount obtained in S30. . Then, based on the correction value, the throttle opening of the throttle valve 28 is corrected to correct the intake air amount. Then, the process proceeds to S32, and in S32, the correction value obtained in S31 is temporarily stored as a learning value, and the correction control is terminated. Note that S31 corresponds to the processing of the throttle opening correction means.

Next, with reference to FIG. 12B, a restart control processing procedure executed by the ECU 40 when restarting the temporarily stopped internal combustion engine 12 in the present embodiment will be described.
When this control is executed, the ECU 40 cranks the internal combustion engine 12 by driving the starter motor 52 in S30. In S41, the ECU 40 reads the learning value stored in the ECU 40, and then proceeds to S42. In S42, the target throttle opening degree Ta is calculated using the learning value stored in S32. At this time, if the condensed water freezes during the steady operation of the internal combustion engine 12 and the intake air amount decreases, the learning value is a value for increasing the throttle opening. Therefore, in S42, when the amount of intake air decreases due to the freezing of condensed water, an increase correction is made to compensate for the decrease, and the throttle opening of the throttle valve 28 is increased stepwise. Thereafter, the ECU 40 executes fuel injection control and ignition timing control of the spark plug 26 to bring the internal combustion engine 12 into a self-sustaining operation state. Note that the processes of S40 and S42 correspond to the processes of the preliminary drive means and the start control means, respectively.

Next, the control content of the start control device for the internal combustion engine in the present embodiment will be described.
While the vehicle 11 is traveling, the internal combustion engine 12 is in steady operation, and at this time, the learning value obtained when the intake air amount of the internal combustion engine 12 is corrected is stored. From this state, when the vehicle 11 is temporarily stopped, such as when waiting for a signal, the internal combustion engine 12 automatically stops. When the vehicle 11 starts traveling from this state, even if the condensed water is frozen because the internal combustion engine 12 is below freezing point, in that case, the throttle opening TA is increased using the learning value. Since the correction is performed, the internal combustion engine 12 can be restarted without any trouble, and the vehicle 11 starts to travel. Further, in the restart control performed by the ECU 40, since the increase in the throttle opening degree TA is corrected using the learning value during steady operation, the vehicle has only the internal combustion engine 12 as a drive source, and the intake passage at the time of cranking When at least the flow rate of the air 23 is increased due to freezing of the condensed water, the increase in the throttle opening degree TA is corrected to ensure good engine startability of the internal combustion engine 12. .

According to this embodiment, in addition to the effects (1) and (4) to (7) described in the first embodiment, the following effects can be obtained.
(12) Here, in the idling stop vehicle, when cranking by the starter motor 52 is performed for a long time when the internal combustion engine 12 is started, the driver feels uncomfortable, so the time of cranking performed by the starter motor 52 Has a limit. However, if cranking cannot be performed for a long time, it is difficult to secure a flow rate necessary for the air flow meter 31 to detect the flow rate during cranking, and the throttle opening is increased based on the intake air amount detected by the air flow meter 31. When determining whether or not to correct, there is a possibility that the start according to the actual flow path resistance cannot be performed with high accuracy. In this regard, in this embodiment, the increase in the throttle opening degree TA is corrected in order to compensate for the decrease in the intake air amount at the time of restart using the learning value during steady operation. Therefore, even if the vehicle 11 uses only the internal combustion engine 12 as a travel drive source, the ECU 40 performs appropriate engine start according to the flow path resistance of the intake passage regardless of the flow rate of the intake passage during cranking. It can be carried out.

  (13) During the steady operation, the ECU 40 determines a correction value according to the difference between the intake air amount of the internal combustion engine 12 during the steady operation and the target intake air amount Gb stored in the map, and learns the correction value. Value. At the time of restart control, the learning value is used to increase the throttle opening degree TA. Therefore, the larger the difference between the actual intake air amount of the internal combustion engine 12 and the target intake air amount Gb during steady operation, the more air can flow through the throttle valve 28 during restart. Therefore, when the internal combustion engine 12 is started, the internal combustion engine 12 can inhale air without excess or deficiency, and better startability can be ensured.

The embodiment described above can also be implemented in a form appropriately modified as follows.
In the first embodiment, the method for obtaining the target intake air amount to be compared with the intake air amount of the internal combustion engine 12 calculated in S14 is not particularly limited, and a well-known method may be adopted as appropriate. For example, the intake system may be divided into elements such as a throttle valve, an intake pipe, and an intake valve of an internal combustion engine, and the intake air amount may be calculated using an air model expressed by a mathematical expression by modeling each physical characteristic. . Then, the calculated intake air amount may be stored in advance in the ECU 40 as the target intake air amount in association with the rotation speed of the internal combustion engine 12, the accelerator opening, and the detection result of the air flow meter 31. In this case, during restart control, the target intake air amount calculated using the air model is compared with the intake air amount calculated from the detection result of the air flow meter 31 in S14. When the intake air amount is smaller than the target intake air amount, the difference between the target intake air amount and the intake air amount is calculated, and a correction coefficient corresponding to the difference is determined to correct the throttle opening increase. I do.

  -In 2nd Embodiment, you may change the content of the comparison process performed by S24. For example, the ECU 40 compares the intake pipe pressure transition when a predetermined time has elapsed after outputting the valve opening command to the EGR valve 34 in S24 with the determination intake pipe pressure transition, and whether the flow path resistance has increased. It may be determined whether or not. In this case, the ECU 40 calculates the amount of change in the intake pipe pressure per unit time based on the intake pipe pressure transition during the period when the EGR valve 34 is opened after the valve opening command is output to the EGR valve 34. Further, the ECU 40 calculates the pressure change amount of the determination pressure based on the determination pressure transition corresponding to the time from when the valve opening command is output until the EGR valve 34 is opened. The ECU 40 determines that the condensed water is not frozen and the flow path resistance is small when the calculated pressure change amount of the intake pipe pressure is equal to the pressure change amount of the determination intake pipe. When the pressure change amount differs from the pressure change amount of the determination intake pipe, it is determined that the flow path resistance has increased. If it is determined whether or not the flow path resistance is increased by such a method, an appropriate start according to the flow path resistance of the intake passage 23 can be performed.

  -In 4th Embodiment, you may make it perform the process which determines whether the increase correction of throttle opening is performed. That is, it is only necessary to perform processing for determining whether or not the flow path resistance is increased based on the learning value obtained during the correction control during steady operation. For example, when it is determined that the flow path resistance is increased using the learning value, the intake air amount correction start is turned on, while when it is determined that the flow path resistance is small, the normal start is turned on. To. When the restart control is performed with the intake air amount correction start being ON, the processes of S40 to S42 are executed. When the restart control is performed with the normal start being ON, the normal start is performed. Just do it.

  The process for determining whether or not to perform the increase correction of the throttle opening need not be performed during the execution of the restart control. For example, in the second embodiment, it may be performed during steady operation. In this case, during steady operation, a process of comparing the pressure transition of the intake pipe pressure and the pressure transition for determination may be performed to determine whether or not the flow path resistance has increased. If the ECU 40 determines that the flow path resistance has increased, the intake air amount correction start is turned ON during steady operation, while the ECU 40 determines that the flow path resistance is low during steady operation. Set normal start to ON. Then, when the restart control is performed with the intake air amount correction start being ON, the processes of S23 and S25 are executed, and when the restart control is performed with the normal start being ON, the process of S22 is performed. If executed, good startability of the internal combustion engine 12 can be secured.

  -You may change the content of the process which determines whether channel resistance is increasing. For example, the process of S14 in the first embodiment is omitted, and in S11, the ECU 40 determines whether or not the intake air temperature is lower than 0 ° C. If the intake air temperature is 0 ° C. or higher, the condensed water is frozen. It may be determined that no flow has occurred and the flow path resistance is small, and the process may proceed to S13.

  -The EGR valve opening sensor 36 may be omitted. For example, if the EGR actuator 35 is constituted by a stepper motor, the opening degree of the EGR valve 34 can be increased without providing a sensor for detecting the opening degree of the EGR valve 34 in addition to the EGR actuator 35. Since it can be detected, the EGR valve opening sensor 36 may be omitted.

  The engine start performed by the start control device of the present embodiment is not limited to a state in which the internal combustion engine 12 mounted on the hybrid vehicle or the idling stop vehicle is temporarily stopped, and the driver presses the key switch. It may be executed when turned on.

  DESCRIPTION OF SYMBOLS 11 ... Vehicle, 12 ... Internal combustion engine, 18 ... Motor generator, 23 ... Intake passage, 23a ... Intake pipe, 23b ... Surge tank, 24 ... Exhaust passage, 28 ... Throttle valve, 29 ... Throttle actuator, 31 ... Air flow meter 32 ... EGR device, 33 ... EGR passage, 34 ... EGR valve, 35 ... EGR actuator, 40 ... permission means, start control means, preliminary drive means, fuel cut control means, calculation means, and throttle opening correction means ECU 41. Intake pipe pressure sensor 52. Starter motor.

Claims (8)

An internal combustion engine start control device including an EGR device that recirculates a part of exhaust gas flowing in an exhaust passage as EGR gas to an intake passage,
A situation in which the decrease in the intake air amount caused by the condensation water contained in the EGR gas frozen on the inner wall of the intake passage is compensated by increasing the throttle opening, and the decrease in the intake air amount is compensated An internal combustion engine start control device comprising start control means for executing engine start under the control of the internal combustion engine. Intake air amount detection means for detecting the intake air amount of the internal combustion engine;
Preliminary drive means for preliminarily driving the internal combustion engine stopped by the electric motor when a predetermined start condition is established;
2. The internal combustion engine according to claim 1, further comprising permission means for permitting the start control means to correct the increase in the throttle opening on the condition that the intake air amount of the internal combustion engine is reduced during the preliminary drive. Engine start control device. Storage means for storing a map for defining a target intake air amount based on the engine rotational speed;
The permission means increases the throttle opening by the start control means on the condition that the intake air amount at the time of preliminary driving of the internal combustion engine is smaller than the target intake air amount based on the engine rotational speed at the time of preliminary driving. Allow corrections,
The start control device for an internal combustion engine according to claim 2, wherein the start control means corrects the throttle opening to increase so that the intake air amount of the internal combustion engine approaches the target intake air amount. The start control of the internal combustion engine according to claim 3, wherein the start control means performs an increase correction of the throttle opening according to a difference between the intake air amount during the preliminary drive of the internal combustion engine and the target intake air amount. apparatus. The EGR device includes an EGR valve that makes the amount of the EGR gas recirculated into the intake passage variable.
Fuel cut control means for executing fuel cut control for interrupting fuel supply to the internal combustion engine;
Valve control means for forcibly opening and closing the EGR valve during execution of fuel cut control by the fuel cut control means;
Permission means for permitting the start control means to correct the increase in the throttle opening on the condition that the pressure transition in the intake passage when the EGR valve is opened and closed is different from a preset pressure transition for determination; The start control device for an internal combustion engine according to claim 1. The permitting unit is configured to output the EGR valve after the compulsory closing command is output to the EGR valve, or between the compulsory opening command output to the EGR valve and the EGR valve to be opened. The start control device for an internal combustion engine according to claim 5, wherein the start control means permits an increase correction of the throttle opening, on the condition that the pressure change in the intake passage is different from the pressure change for determination. The pressure in the intake passage between the time when the EGR valve is closed after the forced valve closing command is output to the EGR valve or the time when the EGR valve is opened after the forced valve opening command is output to the EGR valve A calculation means for calculating the amount of pressure change per unit time based on the transition,
The permission means permits the increase correction of the throttle opening by the start control means on the condition that the pressure change amount calculated by the calculation means is different from the pressure change amount obtained from the determination pressure transition. The start control device for an internal combustion engine according to claim 6. It is mounted on an idling stop vehicle that uses only the internal combustion engine as a travel drive source and starts by cranking the internal combustion engine that is temporarily stopped,
Intake air amount detection means for detecting the intake air amount of the internal combustion engine;
Throttle opening correction means for correcting the throttle opening according to the detection result of the intake air amount detection means during steady operation,
The start control means performs an increase correction of the throttle opening when the throttle opening correction means performs an increase correction of the throttle opening to compensate for a decrease in the intake air amount during steady operation. A start control device for an internal combustion engine as described.

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