JP2016094825A - Start control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a raw gas from being excessively discharged even when increase in rotating speed is delayed due to deterioration of a battery in motoring for starting.SOLUTION: When start of an internal combustion engine is requested (step 1), motoring by using a motor generator is started (step 2), and fuel injection (step 7) and ignition (step 8) are started when a rotating speed is increased to a target rotating speed (step 4). In a case when the increase of the rotating speed is slow, the fuel injection and the ignition are started at a timing when the lapse of time from the start of motoring reaches a prescribed time (step 3). Thus discharge of a raw gas due to the excessively long motoring can be suppressed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a start control device for an internal combustion engine in a hybrid vehicle including an internal combustion engine and a motor / generator as vehicle drive sources.

  In a hybrid vehicle including an internal combustion engine and a motor / generator as vehicle drive sources, the internal combustion engine is stopped and started according to predetermined stop conditions and restart conditions.

  In Patent Document 1, in such a hybrid vehicle, when starting an internal combustion engine, a motor / generator is used to increase the engine rotational speed to a predetermined rotational speed (for example, a rotational speed corresponding to an idle rotational speed). Therefore, a start control is disclosed in which fuel injection and ignition are started to start combustion.

JP 2009-214704 A

  In the start control in which fuel injection and ignition are started after the engine speed is increased to a predetermined speed as described above, fuel injection and ignition are started almost simultaneously with the start of cranking by the starter motor. Compared to the start control of a general vehicle internal combustion engine, the motoring period until the start of combustion is longer. In particular, in a situation where the torque of the motor / generator cannot be sufficiently obtained due to deterioration of the battery or the like, the time required to increase to a predetermined rotational speed becomes long.

  Thus, when the internal combustion engine is motored for a long time, a negative pressure in the cylinder develops, so that a large amount of so-called raw gas is generated and discharged to the outside from the tip of the exhaust passage. The so-called raw gas is a fuel component in which the fuel dissolved in the oil in the crankcase has evaporated, a volatile component of the oil itself, a fuel component that has oozed out from the nozzle of the fuel injection valve, a blow-by gas or canister introduced into the intake system Is a general term for gas containing unburned components such as purge gas from the exhaust gas, EGR gas introduced from the exhaust system into the intake system, gas flowing backward from the exhaust pipe into the combustion chamber, or gas remaining after incomplete combustion. These gases are exhausted to the outside due to the pumping action associated with motoring. Particularly, when a negative pressure develops due to motoring, the amount of generated gas is increased, which is not preferable. .

The present invention includes an internal combustion engine and a motor / generator as vehicle drive sources, and starts fuel injection and ignition after increasing the engine rotational speed to a predetermined rotational speed by the motor / generator when the internal combustion engine is requested to start. In an internal combustion engine start control device,
A parameter that represents the total amount of gas discharged during motoring by the motor / generator is obtained, and fuel injection and ignition are started when the parameter reaches a predetermined value before the engine speed reaches the predetermined speed. It is characterized by that.

  Examples of the parameters include the number of rotations by motoring (in other words, the number of cycles), the elapsed time from the start of motoring, or the total gas amount calculated from the intake air amount per cycle and the number of rotations by motoring. , Etc. can be used.

  In the above configuration, usually, combustion starts when the motor / generator reaches a predetermined rotational speed, but the parameter is set to a predetermined value before the engine rotational speed reaches the predetermined rotational speed. When it reaches, fuel injection and ignition are started at that stage and combustion is started.

  According to the present invention, when it takes a long time for the engine speed to increase to a predetermined speed due to motoring by the motor / generator due to deterioration of the battery or the like, the engine speed is increased to the predetermined speed. Combustion starts without waiting. Therefore, the release of so-called raw gas to the outside is suppressed. In particular, the production of raw gas accompanying the development of negative pressure due to long-time motoring can be suppressed.

The structure explanatory view showing the basic composition of the hybrid vehicle to which this invention is applied. FIG. The flowchart which shows 1st Example of the starting control of this invention. The flowchart which shows 2nd Example of the starting control of this invention. The flowchart which shows 3rd Example of the starting control of this invention. The time chart which shows the effect | action of 2nd Example.

  FIG. 1 is an explanatory diagram showing a basic configuration of a hybrid vehicle to which the present invention is applied. This hybrid vehicle includes an internal combustion engine 1 and a motor / generator 2 as vehicle drive sources, and a belt-type continuously variable transmission 3 as a transmission mechanism. A first clutch 4 is interposed between the crankshaft 6 of the internal combustion engine 1 and the motor / generator 2, and a second clutch 5 is interposed between the motor / generator 2 and the input shaft 7 of the continuously variable transmission 3. Is intervening. The output shaft 8 of the continuously variable transmission 3 is connected to the drive wheels 10 via a final reduction mechanism 9.

  The internal combustion engine 1 is, for example, an in-cylinder direct injection type spark ignition gasoline engine, which performs start control and stop control based on a control command from the engine controller 12 and opens the throttle valve 13 (see FIG. 2). The degree is controlled and fuel cut control or the like is performed.

  The first clutch 4 provided between the internal combustion engine 1 and the rotor of the motor / generator 2 couples the internal combustion engine 1 to the motor / generator 2 or connects the internal combustion engine 1 in accordance with the selected travel mode. When the internal combustion engine 1 is started, motoring of the internal combustion engine 1 is performed by driving the motor / generator 2 with the first clutch 4 engaged.

  The motor / generator 2 is composed of, for example, a three-phase alternating current synchronous motor / generator, and is connected to a traveling battery 14 via an inverter 15. The motor / generator 2 outputs a positive torque based on a control command from the motor controller 16 (so-called power running), a regenerative operation that absorbs the torque to generate electric power and charges the traveling battery 14; Do both.

  A second clutch 5 provided between the motor / generator 2 and the continuously variable transmission 3 transmits and disconnects power between the vehicle drive source including the internal combustion engine 1 and the motor / generator 2 and the drive wheels 10. The engagement / release is controlled via hydraulic pressure based on a control command from the CVT controller 17.

  The belt-type continuously variable transmission 3 has an input-side primary pulley, an output-side secondary pulley, and a metal belt wound between the two, based on a control command from the CVT controller 17. The belt contact radius and thus the gear ratio of each pulley are continuously controlled by the primary hydraulic pressure and the secondary hydraulic pressure generated by the external hydraulic unit.

  The hybrid vehicle control system includes an integrated controller 18 that performs integrated control of the entire vehicle in addition to the engine controller 12, motor controller 16, and CVT controller 17 described above, and each of these controllers 12, 16, 17, 18 are connected via a CAN communication line 19 capable of exchanging information with each other. Further, an accelerator opening sensor 21 for detecting the opening degree of an accelerator pedal operated by the driver, a crank angle sensor 22 for detecting the rotational speed of the internal combustion engine 1, an air flow meter 23 for detecting the intake air amount of the internal combustion engine 1, A water temperature sensor 24 for detecting the water temperature of the internal combustion engine 1, an intake air temperature sensor 25 for detecting the intake air temperature of the internal combustion engine 1, a collector pressure sensor 26 for detecting the collector pressure of the internal combustion engine 1, a vehicle speed sensor 27 for detecting the vehicle speed, a motor Various sensors such as a motor rotation speed sensor 28 for detecting the rotation speed of the generator 2 are provided, and detection signals of these sensors are individually sent to each controller such as the integrated controller 18 or via the CAN communication line 19. Have been entered.

  The hybrid vehicle configured as described above has travel modes such as an electric vehicle travel mode (EV mode), a hybrid travel mode (HEV mode), and a drive torque control start mode (WSC mode). The optimum travel mode is selected according to the state, the accelerator operation of the driver, and the like. Then, the internal combustion engine 1 is automatically stopped and restarted according to the switching of these modes.

  FIG. 2 is an explanatory diagram schematically showing the configuration of the internal combustion engine 1. A pair of intake valves 32 and a pair of exhaust valves 33 are arranged on the ceiling wall surface of the combustion chamber 31. A spark plug 34 is disposed in the center surrounded by 32 and the exhaust valve 33.

  A fuel injection valve 36 that directly injects fuel into the combustion chamber 31 is disposed below the intake port 35 that is opened and closed by the intake valve 32. An electronically controlled throttle valve 13 whose opening is controlled by a control signal from the engine controller 12 is interposed upstream of the collector portion 38 of the intake passage 37 connected to the intake port 35. An air flow meter 23 for detecting the intake air amount is disposed on the upstream side. The collector section 38 is connected to a gas inlet 39 through which a gas such as blow-by gas scavenged from the crankcase, purge gas from a canister (not shown), or EGR gas from an exhaust system is introduced. The gas inlets 39 are actually provided individually corresponding to the respective gases. The intake air temperature sensor 25 and the collector pressure sensor 26 described above are disposed in the collector unit 38, for example.

  An exhaust passage 41 is connected to the exhaust port 40 that is opened and closed by the exhaust valve 33, and the exhaust passage 41 is provided with a catalyst device composed of a three-way catalyst (not shown).

  Next, FIG. 3 is a flowchart showing a first embodiment of start control of the internal combustion engine 1 executed by the engine controller 12. In this embodiment, both the initial start after the vehicle key is turned on and the automatic restart during operation are processed according to this flowchart. In step 1, it is repeatedly determined whether a request for starting the internal combustion engine 1 has been received from the integrated controller 18. If there is a start request, the routine proceeds to step 2 where the motor / generator 2 is driven by setting the first clutch 4 in the engaged state to perform motoring of the internal combustion engine 1.

  In step 3, it is determined whether or not a predetermined time has elapsed since the start of motoring of the internal combustion engine 1. Until the predetermined time elapses, the process proceeds from step 3 to step 4 to determine whether or not the rotational speed of the internal combustion engine 1 has increased to the target rotational speed by motoring. This target rotational speed is, for example, a value corresponding to the idle rotational speed, may be a fixed value, or may be a value that is variably set according to the vehicle operating conditions at that time. Until this target rotational speed is reached, the process returns to step 3 and motoring is continued.

  When the target rotational speed is reached, it is further determined in step 5 whether or not the collector pressure has reached the target negative pressure, and in step 6 it is determined whether or not the intake air amount has reached the target air amount. In the present embodiment, these determinations in steps 5 and 6 are added as a weighting condition to the rotation speed determination in step 4, but these steps 5 and 6 are not necessarily essential in the present invention.

  When the conditions of Steps 4, 5, and 6 are satisfied, the process proceeds to Steps 7 and 8, where fuel injection is started and ignition is started. Thereby, the combustion of the internal combustion engine 1 is started and the start-up is completed. The motor / generator 2 shifts to normal torque control in, for example, the HEV mode, when the internal combustion engine 1 is started.

  On the other hand, if a predetermined time has elapsed from the start of motoring before the conditions of steps 4, 5, and 6 are satisfied, the process proceeds from step 3 to steps 7 and 8, and fuel injection and ignition are similarly started. That is, if the establishment of the conditions of steps 4, 5, and 6 is delayed due to some reason such as deterioration of the traveling battery 14, combustion is started without waiting for the establishment of these conditions. Therefore, a large amount of raw gas does not flow out of the exhaust system due to long-time motoring.

  In FIG. 2, when the internal combustion engine 1 is started, the throttle valve 13 is basically at the minimum opening, and the negative pressure in the combustion chamber 31 is developed by motoring. Therefore, the gas in the crankcase can easily enter the combustion chamber 31 through the clearance of the piston ring, the fuel remaining in the injection port of the fuel injection valve 36 is vaporized, and the blow-by gas introduced into the collector portion 38 is introduced. Gas flows into the combustion chamber 31. That is, the production amount of raw gas increases due to the development of negative pressure. And these raw gases will be pushed out to the exhaust passage 41 side by the pump action accompanying motoring. In the above embodiment, even when the increase in the rotational speed is delayed due to deterioration of the traveling battery 14 or the like, the combustion starts at the time when a predetermined time elapses, so that the raw gas is not excessively released to the outside.

  Next, FIG. 4 is a flowchart showing a second embodiment of start control according to the present invention. In the second embodiment, the process of step 3A is performed instead of the process of step 3 in the first embodiment shown in FIG. 2, and the other steps are the same as those of the first embodiment. There is no particular change.

  That is, in the second embodiment, as Step 3A, it is determined whether or not the number of rotations of the crankshaft 6 from the start of motoring has reached a predetermined number or more. , Go to step 8. Therefore, when the conditions of steps 4, 5, and 6 are delayed due to deterioration of the traveling battery 14, combustion is started when the crankshaft 6 is rotated a predetermined number of times, and excessive release of raw gas is avoided. Is done. Since the amount of gas flowing from the intake system of the internal combustion engine 1 to the exhaust system through the combustion chamber 31 basically correlates with the number of rotations of the crankshaft 6 (in other words, the number of cycles), it is ensured that excessive raw gas is released. Can be avoided.

  Next, FIG. 5 is a flowchart showing a third embodiment of start control according to the present invention. In the third embodiment, the process of step 3B is performed instead of the process of step 3 in the first embodiment shown in FIG. 2, and the other steps are the same as those of the first embodiment. There is no particular change.

  That is, in this third embodiment, as step 3B, it is determined whether or not the total gas amount that has passed through the combustion chamber 31 from the start of motoring has become a predetermined amount or more, and the total gas amount reaches the predetermined amount. Then, go to Steps 7 and 8. The total amount of gas flowing during motoring can be obtained from the amount of intake air per cycle and the number of rotations of the crankshaft 6 by motoring (in other words, the number of cycles). The intake air amount per cycle may be calculated from the flow rate detected by the air flow meter 23, or the geometric in-cylinder volume at the closing timing of the intake valve 32 is regarded as the intake air amount per cycle. Also good. Further, correction is made to the geometric in-cylinder volume at the intake valve closing timing using the pressure and temperature of the intake air at the closing timing of the intake valve (alternatively, the collector pressure and the intake air temperature at the collector portion 38 can be used). You may do it.

  Therefore, in this embodiment, even when the conditions of steps 4, 5, and 6 are delayed due to deterioration of the traveling battery 14, the maximum amount of raw gas released from the exhaust passage 41 is reliably within a predetermined range. Limited.

  FIG. 6 is a time chart for explaining the operation of the second embodiment as an example. At time t1, a start request for the internal combustion engine 1 is output, and motoring using the motor / generator 2 is started. Thereby, the rotational speed of the internal combustion engine 1 increases, and the collector pressure (cylinder pressure) decreases. Here, the broken line shown as the “comparative example” indicates the characteristic when the driving battery 14 is not deteriorated and the original rotation speed is increased. In this case, the motoring is started at time t1. After that, at time t2, the rotational speed increases to a predetermined target rotational speed, and fuel injection and ignition are started. Accordingly, the raw gas flows out between the times t1 and t2.

  On the other hand, when the traveling battery 14 is deteriorated, as shown by the solid line, the increase in the rotational speed becomes slow, and the target rotational speed is not reached at time t2. Assuming that the motoring is continued as it is, the target rotational speed is reached at time t3 as indicated by a virtual line a. Therefore, the raw gas is continuously released over a long period from time t1 to t3, and the generation of the raw gas is promoted by the negative pressure development in the combustion chamber 31 as described above.

  In such a case, in the second embodiment, fuel injection and ignition are started and combustion is performed at a stage where the crankshaft 6 has rotated a predetermined number of times from the start of motoring, for example, at time t4. Therefore, the raw gas is not released excessively long.

  In the other first and third embodiments, the same operation as the time chart of FIG. 5 is obtained.

  The embodiment in which the present invention is applied to the direct injection internal combustion engine has been described above. However, the present invention is not limited to the direct injection internal combustion engine, and is a port injection internal combustion engine in which a fuel injection valve is provided in the intake port. The same applies to the above.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Motor generator 4 ... 1st clutch 12 ... Engine controller

Claims (6)

Starting an internal combustion engine having an internal combustion engine and a motor / generator as a vehicle drive source, and starting fuel injection and ignition after the engine / generator has increased the engine rotational speed to a predetermined rotational speed when the internal combustion engine is requested to start In the control device,
A parameter that represents the total amount of gas discharged during motoring by the motor / generator is obtained, and fuel injection and ignition are started when the parameter reaches a predetermined value before the engine speed reaches the predetermined speed. A start control device for an internal combustion engine.   2. The start control device for an internal combustion engine according to claim 1, wherein the number of rotations by motoring is used as the parameter, and fuel injection and ignition are started when the number of rotations reaches a predetermined value.   2. The internal combustion engine start control according to claim 1, wherein an elapsed time from the start of motoring is used as the parameter, and fuel injection and ignition are started when the elapsed time reaches a predetermined value. apparatus.   As the parameter, the total gas amount is obtained from the intake air amount per cycle and the number of rotations by motoring, and when the total gas amount reaches a predetermined value, fuel injection and ignition are started. The start control device for an internal combustion engine according to claim 1.   5. The start control device for an internal combustion engine according to claim 4, wherein an intake air amount per cycle is obtained from an in-cylinder volume at the intake valve closing timing.   6. The start control apparatus for an internal combustion engine according to claim 5, wherein the intake air amount per cycle is corrected based on at least one of intake pressure and temperature at the intake valve closing timing.

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