JP6812065B2 - Internal combustion engine control device - Google Patents

Description

The present invention relates to a control device that controls the operation of the internal combustion engine, and more particularly to a control device that controls the timing of ignition of the air-fuel mixture immediately after the start of the internal combustion engine.

When starting a stopped internal combustion engine, the crankshaft, which is the output shaft of the internal combustion engine, is rotationally driven by an electric motor, and fuel is injected from the injector to burn it in the cylinder to accelerate the rotation of the crankshaft. Crank. Cranking is performed when the internal combustion engine goes from the initial explosion to the continuous explosion and the rotation speed of the crankshaft, that is, the engine speed exceeds the threshold value determined according to the cooling water temperature of the internal combustion engine (assuming that the explosion is complete). )finish.

Immediately after the start of the internal combustion engine, that is, immediately after the end of cranking, the gap between the electrodes of the spark plug is widened, deposits are accumulated in the combustion chamber of the spark plug and cylinder, and the intake air leaks from the cylinder during the compression stroke. Due to the disturbance factor, the combustion state of the air-fuel mixture may be deteriorated, the output torque of the internal combustion engine may be reduced, and the engine speed may be lowered without being appropriately increased.

In order to suppress such a decrease in engine speed, for example, as disclosed in the following patent documents, the engine speed is less than a predetermined set speed, and the rate of decrease in engine speed (per unit time). When the amount of decrease) exceeds the set value, it is conceivable to carry out correction control to increase the fuel injection amount to increase the engine torque.

However, with the above method, there is a concern that the control may be delayed and the engine speed may fluctuate significantly, causing vibration and noise to give the user a sense of discomfort. In the worst case, the risk of engine stall cannot be completely eliminated.

Jikkenhei 03-051154

An object of the present invention is to appropriately suppress a decrease in engine speed immediately after the start of an internal combustion engine.

It controls the timing of ignition of the air-fuel mixture immediately after the start of the internal combustion engine, and the rotation speed of the crankshaft based on the time required for the crankshaft to rotate by a predetermined angle and the crankshaft by the predetermined angle. The difference from the crankshaft rotation speed based on the time required to rotate at a larger angle is obtained, and the difference is compared with the judgment value to determine whether the engine rotation speed is accelerating properly. If it is determined that the engine speed is not accelerating properly, it is determined that the engine speed is accelerating properly from the time of such judgment to the time when the cylinder of the internal combustion engine is ignited a predetermined number of times. A control device for an internal combustion engine is configured in which the minimum advance amount of the ignition timing is increased as compared with the case where the ignition timing is performed, and the minimum advance amount of the ignition timing is restored after a predetermined number of ignitions are performed .

More specifically, the amount of advance of the ignition timing is adjusted so as to reduce the deviation between the measured engine speed and the target idle speed immediately after the cranking for starting the internal combustion engine is completed. The feedback control is performed, and the minimum advance amount is the minimum amount of the advance angle of the ignition timing adjusted through the feedback control .

Further, the ignition timing at the time immediately after the start of cranking is delayed as compared with the ignition timing during cranking for starting the internal combustion engine .

According to the present invention, it is possible to appropriately suppress a decrease in the engine speed immediately after the start of the internal combustion engine.

The figure which shows the schematic structure of the internal combustion engine for a vehicle and the control device in one Embodiment of this invention. The figure which shows the structure of the drive system of the vehicle in the same embodiment. A timing diagram showing the transition of the increase in engine speed and the stroke of each cylinder in the period immediately after the start of the internal combustion engine. The timing diagram which shows the pattern of the control of the ignition timing by the control device of the same embodiment.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle according to the present embodiment. The internal combustion engine of the present embodiment is a spark-ignition type 4-stroke engine, and includes a plurality of cylinders 1 (for example, three cylinders, one of which is illustrated in FIG. 1). An injector 11 for injecting fuel is provided for each cylinder 1 in the vicinity of the intake port of each cylinder 1. Further, a spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives the application of the induced voltage generated by the ignition coil and induces a spark discharge between the center electrode and the ground electrode. The ignition coil is integrally built in the coil case together with the igniter which is a semiconductor switching element.

The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. An air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream on the intake passage 3.

The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 to the outside from the exhaust port of each cylinder 1. An exhaust manifold 42 and a three-way catalyst 41 for purifying exhaust gas are arranged on the exhaust passage 4.

The exhaust gas recirculation device 2 realizes a so-called high-pressure loop EGR, and is an external EGR that communicates the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3. The elements are a passage 21, an EGR cooler 22 provided on the EGR passage 21, and an EGR valve 23 that opens and closes the EGR passage 21 and controls the flow rate of EGR gas flowing through the EGR passage 21. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined position downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined position downstream of the throttle valve 32 in the intake passage 3, particularly a surge tank 33.

FIG. 2 shows an example of a drive system included in the vehicle. This drive system includes a torque converter 7 and automatic transmissions 8 and 9. In particular, in the present embodiment, as the components of the automatic transmissions 8 and 9, a forward / backward switching device 8 using a planetary gear mechanism and a belt-type CVT (Continuously Variable Transmission) 9 which is a kind of continuously variable transmission are adopted. doing.

The rotational torque output by the internal combustion engine is input from the crankshaft, which is the output shaft of the internal combustion engine, to the pump impeller 71 on the input side of the torque converter 7, and is transmitted to the turbine runner 72 on the output side. The rotation of the turbine runner 72 is transmitted to the drive shaft 94 of the CVT 9 via the forward / backward switching device 8, and the driven shaft 95 is rotated through the shift in the CVT 9. The rotation of the driven shaft 95 is transmitted to the output gear 101. The output gear 101 meshes with the ring gear 102 of the differential device, and rotates the axle 103 and thus the drive wheels via the differential device.

The torque converter 7 includes a lockup mechanism. The lockup mechanism is known in this field, and is an operation for disconnecting and switching between a lockup clutch 73 that engages the input side and the output side of the torque converter 7 so as not to rotate relative to each other and the lockup clutch 73. The element is a lock-up solenoid valve that controls hydraulic pressure (flood control). The lockup solenoid valve is a flow rate control valve that receives a control signal o and changes its opening degree.

In a vehicle equipped with the CVT 9, the torque converter 7 is almost always locked up when the vehicle speed is equal to or higher than a predetermined value (for example, 10 km / h). When the vehicle speed falls below a predetermined value, the lockup of the torque converter 7 is released.

The forward / reverse switching device 8 has a sun gear 81 in contact with the turbine runner 72 and a ring gear 82 in contact with the drive shaft 94. A forward brake 84, which is a hydraulic clutch that can be switched between disconnection and disconnection, is interposed between the planetary carrier 83 that supports the planetary gear 831 and the transmission case. Further, a reverse clutch 85, which is a hydraulic clutch that can be switched between disconnection and disconnection, is also interposed between the planetary carrier 83 and the sun gear 81 (or the output side of the torque converter 7).

In the D range of the traveling range, the forward brake 84 is engaged and the reverse clutch 85 is disengaged. As a result, the rotation of the output shaft of the torque converter 7 is reversed and decelerated and transmitted to the drive shaft 94, resulting in forward traveling. On the other hand, in the R range, the reverse clutch 85 is engaged and the forward brake 84 is disengaged. As a result, the sun gear 81 and the planetary carrier 83 rotate integrally, and the output shaft of the torque converter 7 and the drive shaft 94 are directly connected to each other to drive in reverse. The solenoid valve that controls the hydraulic pressure for disconnecting and switching the forward brake 84 or the reverse clutch 85 is a flow control valve that receives a control signal p and changes its opening degree.

In the N range and P range, which are non-traveling ranges, both the forward brake 84 and the reverse clutch 85 are disengaged.

The CVT 9 includes a drive pulley 91 and a driven pulley 92, and a belt 93 wound around both pulleys 91 and 92 as elements. The drive pulley 91 is arranged on the back of the fixed sheave 911 fixed to the drive shaft 94, the movable sheave 912 supported on the drive shaft 91 so as to be displaced in the axial direction via a roller spline, and the movable sheave 912. It has a hydraulic servo 913, and the gear ratio can be changed steplessly by operating the hydraulic servo 913 to displace the movable sheave 912. Further, the driven pulley 92 is arranged on the rear back of the fixed sheave 921 fixed to the driven shaft 95, the movable sheave 922 supported on the driven shaft 95 so as to be displaced in the axial direction via a roller spline, and the movable sheave 922. It has the hydraulic pressure servo 923 provided, and gives the belt thrust necessary for torque transmission by operating the hydraulic pressure servo 923 and displacing the movable sheave 922.

The ECU (Electronic Control Unit) 0, which is a control device for an internal combustion engine of the present embodiment, is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

The input interface of ECU0 includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from a crank angle sensor that detects the rotation angle of the crank shaft and the engine rotation speed, and an accelerator pedal. Accelerator opening signal c output from a sensor that detects the amount of depression or the opening of the throttle valve 32 as the accelerator opening (so to speak, the required engine load), the intake passage 3 connected to the cylinder 1 (particularly, the surge tank 33). ), The intake air temperature / intake pressure signal e output from the temperature / pressure sensor that detects the intake air temperature and the intake pressure, and the cooling water temperature signal f that is output from the water temperature sensor that detects the cooling water temperature that suggests the temperature of the internal combustion engine. To know the battery current / voltage signal g output from the sensor that detects the terminal current or terminal voltage of the vehicle-mounted battery, and the range (running range or non-running range) of the shift lever (select lever) of the vehicle. The shift range signal h and the like output from the sensor for this purpose are input.

From the output interface of ECU 0, the ignition signal i is for the igniter attached to the ignition plug 12, the fuel injection signal j is for the injector 11, the opening operation signal k is for the throttle valve 32, and the EGR valve 23 is open. Degree operation signal l, opening control signal for the lockup solenoid valve for switching the disconnection / disconnection of the lockup clutch 73 o, opening control signal for the solenoid valve for switching the disconnection / disconnection of the forward brake 84 or the reverse clutch 85 The gear ratio control signal q and the like are output to p and CVT9.

The processor of ECU 0 interprets and executes a program stored in the memory in advance, calculates an operation parameter, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for the operation control of the internal combustion engine via the input interface, obtains the engine speed, and fills the cylinder 1. Estimate the amount of intake air. Then, based on the engine speed and intake amount, the required fuel injection amount, fuel injection timing (including the number of fuel injections per combustion), fuel injection pressure, ignition timing, required EGR rate (or EGR). Amount), whether or not to lock up the torque converter 7, and various operating parameters such as the gear ratio of the CVT 9 are determined. The ECU 0 applies various control signals i, j, k, l, o, p, and q corresponding to the operation parameters via the output interface.

Further, the ECU 0 controls to operate the electric motor (starter motor or ISG (Integrated Starter Generator)) when the internal combustion engine is started (it may be a cold start or a return from the idling stop). The signal n is input to the electric motor, and the electric motor performs cranking to rotate the crankshaft. The cranking for starting the internal combustion engine ends when the internal combustion engine goes from the first explosion to the continuous explosion and the engine speed, that is, the rotation speed of the crankshaft exceeds the threshold value (assuming that the explosion is complete). .. The threshold value of the engine speed, which is the end condition of cranking, may fluctuate according to the temperature of the internal combustion engine or the like. Specifically, the lower the cooling water temperature of the internal combustion engine, the higher the setting, but it is about 500 rpm.

In the ECU 0 of the present embodiment, the air-fuel mixture filled in the cylinder 1 is charged in the period immediately after the start of the internal combustion engine, in other words, in the period from the end of cranking to the convergence of the engine speed to the required target idle speed. The timing of spark ignition to the engine is controlled, and the decrease in engine speed is appropriately suppressed.

As shown in FIG. 4, the ignition timing until the end point of cranking t ₀ , that is, during cranking, is a relatively advanced constant timing, for example, 5 ° CA (crank) from the compression top dead center of cylinder 1. Angle) It is fixed at an early timing. Then, after t ₀ when the internal combustion engine is completely detonated and cranking is completed, the ignition timing is adjusted according to the current engine speed, the cooling water temperature of the internal combustion engine, and the like. For example, the deviation between the current measured engine speed and the target idle speed is calculated, and the amount of advance of the ignition timing and thus the magnitude of the engine torque are adjusted so as to reduce the deviation. Incidentally, in the feedback control that makes the measured engine speed follow the target idle speed, the opening degree of the throttle valve 32 is operated to increase or decrease the amount of intake air charged in the cylinder 1 according to the deviation between the two, or the injector 11 The valve opening time may be adjusted to increase or decrease the fuel injection amount. Further, the lower the cooling water temperature of the internal combustion engine, the more the ignition timing is advanced to stabilize the combustion of the air-fuel mixture in the combustion chamber of the cylinder 1.

As a result of these, the ignition timing after t ₀ at the end of cranking is delayed from the ignition timing during cranking. However, the advance amount of the ignition timing of the air-fuel mixture must be set to be equal to or more than the minimum retardation amount. That is, there is a limit to delaying the ignition timing.

Immediately after the start of the internal combustion engine, disturbance factors such as expansion of the gap between the electrodes of the spark plug 12, accumulation of deposits in the combustion chamber of the spark plug 12 or cylinder 1, leakage of intake air from cylinder 1 during the compression stroke, etc. When the combustion state of the air-fuel mixture deteriorates, the output torque of the internal combustion engine decreases and the engine speed rises appropriately toward the target idle speed, coupled with the delay of the ignition timing due to the end of cranking. There is a risk that it will drop without doing so.

In order to appropriately suppress such a decrease in the engine speed, the ECU 0 determines the rotation speed of the crankshaft based on the time required for the crankshaft to rotate by a predetermined angle and the angle at which the crankshaft is larger than the predetermined angle. By obtaining the difference from the rotation speed of the crankshaft based on the time required for rotation and comparing the difference with the judgment value, it is judged whether or not the engine speed is accelerating properly, and the judgment result is obtained. Correction control is performed to change the ignition timing according to the above.

FIG. 3 illustrates the transition of the increase in the engine speed immediately after the start of the internal combustion engine. FIG. 3 shows an example of a three-cylinder engine that explodes at equal intervals. In FIG. 3, the scale along the crank angle on the horizontal axis is attached every 30 ° CA. The black-filled square plot points are the most recently measured engine speeds based on the time required for the crankshaft to rotate 30 ° CA. This can also be seen as the moving average value of the engine speed during the period when the crankshaft rotates 30 ° CA. As is clear from FIG. 3, the engine speed based on the time required for the crankshaft to rotate by 30 ° CA fluctuates depending on which stroke each cylinder 1 of the internal combustion engine is currently in.

On the other hand, the plot points with unfilled circles located on the one-point chain line indicate that the crankshaft rotates 240 ° CA (720 ° CA divided by the number of cylinders of the internal combustion engine), which was measured most recently. It is the engine speed based on the time required. This can also be seen as the moving average of the engine speed during the period when the crankshaft rotates 240 ° CA. The engine speed based on the time required for the crankshaft to rotate 240 ° CA is smoothed with less vertical vibration than the engine speed based on the time required for the crankshaft to rotate 30 ° CA.

The ECU 0 has the same timing as the engine speed based on the time required for the crankshaft rotation for the nearest 30 ° CA of the timing T each time the timing T of 120 ° CA comes after the compression top dead point of each cylinder 1. The difference from the engine speed based on the time required for the crankshaft rotation for the latest 240 ° CA of T is obtained. This difference is, so to speak, the distance between the plot points of the quadrangle and the plot points of the circles located on the scale of the timing T in FIG.

The determination timing T is a time when any of the cylinders 1 has reached the expansion stroke and the engine speed accelerates. Therefore, if the engine speed is properly accelerating toward the target idle speed, the former engine speed based on the time required for the crankshaft to rotate 30 ° CA will be 240 ° CA for the crankshaft. It should exceed the latter engine speed based on the time required to rotate, and the difference between the two should be larger than a certain amount. Therefore, when the difference obtained by subtracting the latter engine speed from the former engine speed is equal to or greater than the judgment value, the ECU 0 determines that the engine speed is accelerating appropriately, and the difference is lower than the judgment value. In this case, it is determined that the engine speed is not accelerating properly.

It should be noted that the time required for the crankshaft to rotate 240 ° CA and the time required for the crankshaft to rotate 30 ° CA measured immediately before the determination timing T (from the former required time to the latter required). The difference (obtained by subtracting the time) is calculated, and if the difference is greater than or equal to the judgment value, it is determined that the engine speed is accelerating appropriately, and if the difference is less than the judgment value, the engine speed is appropriate. It may be determined that the vehicle is not accelerating. The difference is effectively the difference between the engine speed based on the time required for the crankshaft to rotate 30 ° CA and the rotation speed of the crankshaft based on the time required for the crankshaft to rotate 240 ° CA. Corresponds to.

Therefore, when the ECU 0 determines that the engine speed is not properly accelerating, the minimum advance amount of the ignition timing is increased as compared with the case where it is determined that the engine speed is properly accelerating. Do more. That is, when it is determined that the engine speed is not accelerating properly, the limit of retarding the ignition timing is raised as compared with the case where it is not, and the state in which the ignition timing is further advanced is maintained. In FIG. 4, the time point t ₁ is the time point when it is determined that the engine speed is not accelerating properly. The time point t ₁ coincides with any determination timing T. Then, while the transition of the advance angle amount of the ignition timing when it is determined that the engine speed is not accelerating properly is represented by a thick broken line, the ignition timing when it is determined that the engine speed is accelerating properly The transition of the amount of advance angle is represented by a thin solid line.

When it is determined that the engine speed is not accelerating properly, the minimum advance amount of the ignition timing is set to be larger, that is, the period for raising the limit of retarding the ignition timing is the time when such a determination is made. It is from t ₁ to the time point t ₂ when a predetermined number of times (for example, about 7 to 8 times) of ignition is performed in the cylinder 1 of the internal combustion engine. After the ignition has been executed a predetermined number of times, the minimum advance amount of the ignition timing is reset to the original value, that is, the limit of the retarding of the ignition timing that has been raised is restored.

However, it is based on the time required for the crankshaft to rotate 30 ° CA at the judgment timing T visited during the period when the limit of retarding the ignition timing is raised (from time point t ₁ to time point t ₂ ). If it is determined that the difference between the engine speed and the engine speed based on the time required for the crankshaft to rotate 240 ° CA is greater than or equal to the judgment value and the engine speed is accelerating properly, it is still predetermined. Even if the number of ignitions is not executed, the limit of retarding the ignition timing that has been raised is restored.

The judgment value to be compared with the difference in the engine speed at the judgment timing T is changed according to the engine speed at that time and the cooling water temperature of the internal combustion engine. As already described, after the cranking for starting the internal combustion engine is completed, as a general rule, feedback control is carried out to make the engine speed follow the target idle speed. According to this feedback control, the smaller the deviation between the actually measured engine speed and the target idle speed, the smaller the acceleration of the engine speed. Therefore, the difference between the engine speed based on the time required for the crankshaft to rotate 30 ° CA and the engine speed based on the time required for the crankshaft to rotate 240 ° CA is also small. Therefore, the judgment value to be compared with the difference in the engine speed at the judgment timing T is 240 for the crankshaft even if it is based on the current engine speed (the time required for the crankshaft to rotate 30 ° CA). It is preferable to set the value so that the deviation between ° CA rotation (which may be based on the time required for rotation) and the target idle speed is reduced.

In addition, the target idle speed is affected by the current cooling water temperature of the internal combustion engine and the shift range of the vehicle. Specifically, the lower the cooling water temperature, the higher the target idle speed is set. The basic value of the target idle speed is about 750 rpm, but this is increased to 800 rpm to 1000 rpm under the condition that the temperature of the internal combustion engine is low and the friction loss is large. Further, the traveling range in which the crankshaft and the axle of the internal combustion engine are connected (the clutch 8 interposed between them is engaged) and the non-traveling in which the crankshaft and the axle are separated (the clutch 8 is released) A different target idle speed is set for the range. As the target idle speed fluctuates, the magnitude of the deviation between the actually measured engine speed and the target idle speed also changes, and as a result, the judgment value to be compared with the difference in the engine speed at the judgment timing T also changes. It will be.

In the present embodiment, the timing of ignition of the air-fuel mixture in the period immediately after the start of the internal combustion engine is controlled, and the crank based on the time required for the crankshaft to rotate by a predetermined angle (for example, 30 ° CA). A crankshaft based on the rotational speed of the shaft (which is also the moving average of the rotational speeds over a period of 30 ° CA) and the time it takes for the crankshaft to rotate by an angle greater than the predetermined angle (eg 240 ° CA). The difference from the rotation speed (which is also the moving average of the rotation speed during the period of 240 ° CA) is obtained, and the difference is compared with the judgment value to judge whether the engine speed is accelerating properly and the engine. The control device 0 of the internal combustion engine that changes the ignition timing according to the determination result of whether or not the rotation speed is appropriately accelerated is configured.

According to the present embodiment, a decrease in the rotational speed of the crankshaft is quickly detected when the ignition timing is switched from a fixed timing during cranking to a timing determined by calculation immediately after the start of the internal combustion engine. Then, the ignition timing can be corrected. Therefore, it is possible to appropriately suppress a decrease in the engine speed. It is possible to prevent the engine speed from fluctuating due to the delay in control, and to solve the problem that vibration and noise are generated and give the user a sense of discomfort. In addition, engine stall can be reliably prevented immediately after the start of the internal combustion engine.

Then, when it is determined that the engine speed is not accelerating properly, the minimum advance amount of the ignition timing is increased as compared with the case where it is determined that the engine speed is accelerating properly. This does not prevent the ignition timing from being advanced when it becomes necessary to further advance the ignition timing and increase the engine torque due to a disturbance factor.

In addition, since the determination value is changed according to the current engine speed and the cooling water temperature of the internal combustion engine, it is possible to correctly determine whether or not the engine speed is accelerating appropriately. The present invention is not limited to the embodiments described in detail above. The specific configuration of each part, the content of the process, and the like can be variously modified without departing from the spirit of the present invention.

The present invention can be applied to the control of an internal combustion engine mounted on a vehicle or the like.

0 ... Control device (ECU)
1 ... Cylinder 12 ... Spark plug b ... Crank angle signal f ... Cooling water temperature signal h ... Shift range signal i ... Ignition signal n ... Electric motor control signal for cranking

Claims (3)

It controls the timing of ignition of the air-fuel mixture immediately after the start of the internal combustion engine.
Obtain the difference between the rotation speed of the crankshaft based on the time required for the crankshaft to rotate by a predetermined angle and the rotation speed of the crankshaft based on the time required for the crankshaft to rotate by an angle larger than the predetermined angle. By comparing the difference with the judgment value, it is judged whether the engine speed is accelerating properly.
When it is determined that the engine speed is not accelerating properly, it is determined that the engine speed is accelerating properly from the time when such a judgment is made to the time when the cylinder of the internal combustion engine is ignited a predetermined number of times. A control device for an internal combustion engine that increases the minimum advance amount of ignition timing as compared with the case where the ignition timing is performed, and restores the minimum advance amount of ignition timing after a predetermined number of ignitions have been performed . Immediately after the cranking for starting the internal combustion engine is completed, feedback control is performed to adjust the amount of advance of the ignition timing so as to reduce the deviation between the measured engine speed and the target idle speed. And
The control device for an internal combustion engine according to claim 1 , wherein the minimum advance amount is a minimum amount of advance angle of ignition timing adjusted through the feedback control . The control device for an internal combustion engine according to claim 1 or 2 , wherein the ignition timing at the time immediately after the start of cranking is delayed as compared with the ignition timing during cranking for starting the internal combustion engine.

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