JP2014148898A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain torque increase with good responsiveness without causing a racing phenomenon when an instant angular speed is rapidly reduced due to some factors during idling.SOLUTION: A flameout prediction instant peak angular speed R2 higher than a flameout prevention instant peak angular speed 1 is set, and when an instant peak angular speed is lower than the flameout prediction instant peak angular speed R2, an inflow air amount is increased at first, and ignition timing is retarded from a reference point. Thus, a standby state can be achieved without causing racing. The inflow air amount and the ignition timing are returned to the original state when the instant angular speed is returned to the original speed, and the ignition timing is advanced when the instant angular speed is decreased to the flameout prevention instant peak angular speed. The inflow air amount is increased, and therefore, torque can be instantly increased by advancing the ignition timing. Accordingly, an engine stall can be surely prevented while keeping idling engine speed as low as possible.

Description

  The present invention relates to a spark ignition internal combustion engine characterized by idling control, and in particular, a vehicle internal combustion engine is a suitable target.

  In an internal combustion engine for a vehicle, the idling rotational speed is feedback-controlled to improve fuel efficiency. In other words, although the set value of the idling speed is set, the actual speed varies depending on various factors. Therefore, the actual speed is set by detecting the actual speed and feeding back the information. The inflow air amount (and the fuel injection amount) and the ignition timing are adjusted so as to coincide with the rotation speed (ICS: idle control system).

  However, the rotational speed may decrease instantaneously for some reason. In this case, the feedback control may not be able to respond instantaneously, leading to engine stall. In particular, recent internal combustion engines for vehicles tend to set the idling engine speed low in order to improve fuel efficiency, and therefore an instantaneous decrease in engine speed tends to lead to an engine stall.

  Therefore, as described in Patent Document 1, for example, when the instantaneous peak angular velocity of the crankshaft is detected and the instantaneous peak angular velocity is reduced to the misfire-preventing instantaneous peak angular velocity that causes engine stall, feedback control with the set value as a target is performed. It has been proposed to switch to open control for the purpose of improving the output to increase the amount of air flowing into the cylinder, increase the fuel injection amount, and advance the ignition timing to increase the torque.

JP 2006-46263 A

  Increasing the amount of air flowing into the cylinder and the fuel is an indispensable countermeasure to increase the engine output, but there is a certain distance from the electronic throttle (throttle valve) to the cylinder. There is a slight time lag until the rotational speed actually increases (torque increases) after opening. In addition to such a time lag, in Patent Document 1, since the instantaneous peak angular velocity is reduced to the misfire prevention instantaneous peak angular velocity, the inflowing air amount is increased. There is a risk of stalling.

  That is, in Patent Document 1, since it is a response immediately before the engine stalls, not only the measures for preventing misfire are slow, but also there is a time lag between the opening of the electronic throttle and the combustion, so the response is poor in a double sense As a result, it can be said that it is difficult to accurately prevent engine stalls caused by external disturbance factors.

  In addition, switching from feedback control to open control causes the rotational speed to increase at a stretch, resulting in a racing phenomenon such as idling, which may cause discomfort and anxiety to the driver and passengers.

  The present invention has been made to improve the current situation.

  The internal combustion engine of the present invention includes a rotation sensor capable of finely detecting the angular velocity of the crankshaft, an electronic throttle capable of arbitrarily controlling the amount of air flowing into the cylinder, a spark plug, and the electronic sensor based on a signal from the rotation sensor. And a control means for controlling the throttle and the spark plug (the fuel injection amount is calculated according to the air amount, and the fuel injection amount increases and decreases when the inflow air amount increases and decreases).

And, an instantaneous angular velocity that is lower than a safe instantaneous angular velocity that does not cause a stall and higher than a misfire preventing instantaneous angular velocity for preventing a stall is set in advance as a misfiring predictive instantaneous angular velocity, and by the control means,
1) As a reference step, when the instantaneous angular velocity detected by the rotation sensor is lower than the misfire sign instantaneous angular velocity and higher than the misfire prevention instantaneous angular velocity, the inflow air amount is increased by the electronic throttle and the ignition timing is retarded. To
2) If the instantaneous angular velocity detected by the rotation sensor after the reference step exceeds the misfire-predictive instantaneous angular velocity, then return the inflow air amount and the ignition timing.
3) If the instantaneous angular velocity detected by the rotation sensor after the reference step is lower than the misfire prevention instantaneous angular velocity, the ignition timing is advanced to a state before the reference step or higher.
Control is made.

  In the step of returning the inflow air amount and the ignition timing when the instantaneous angular velocity detected by the rotation sensor after the reference step exceeds the misfire indication instantaneous angular velocity, it is possible to return immediately when the misfire indication instantaneous angular velocity is exceeded. However, in anticipation of safety, it is preferable to return to the original state after a preset time has elapsed after the misfire sign instantaneous angular velocity has been exceeded. The same applies to the return control after the instantaneous angular velocity is lower than the misfire prevention instantaneous angular velocity and the inflow air amount is increased and the ignition timing is advanced.

  The angular velocity is an angle at which the crankshaft rotates per unit time, which is synonymous with the number of rotations. That is, the rotation speed is defined as the rotation amount of the shaft per unit time, but if the rotation amount is regarded as an angle, it becomes an angular velocity. The rotation sensor is fixed to the engine body, and the angular speed (or the number of rotations) of the crankshaft is detected by detecting protrusions formed at predetermined intervals on the outer periphery of a disk-shaped rotor fixed to the crankshaft. However, since the outer diameter of the rotor is constant, the angular speed of the rotor is synonymous with the peripheral speed of the rotor. Accordingly, in the present invention, both the rotational speed and the peripheral speed are substantially included in the angular speed.

  Further, according to the present invention, when viewed in relation to the rotational posture of the crankshaft (or the position of the piston), the detection position of the safe instantaneous angular velocity, the misfire prevention instantaneous angular velocity, and the misfire sign instantaneous angular velocity can be based on an arbitrary position. When the instantaneous peak angular velocity is used as a reference, as in the embodiment, there is an advantage of excellent accuracy and responsiveness, which is preferable.

  In the present invention, before the instantaneous angular velocity reaches the misfire-preventing instantaneous angular velocity, misfire is predicted and the inflow air amount is increased in advance to prepare for torque increase. When the angular velocity is reached, the torque can be increased immediately by advancing the ignition timing.

  In other words, since the ignition timing can be controlled immediately, when a tendency (sign) of a decrease in the instantaneous angular velocity appears, preparation for torque increase is made by increasing the amount of inflow air, and the instantaneous angular velocity is reduced to the misfiring prevention instantaneous angular velocity. The case can be handled instantly. For this reason, it is possible to accurately prevent the engine stall from occurring due to an external factor while improving the fuel consumption by reducing the idling rotational speed as much as possible.

  In the present invention, when the misfire-predictive instantaneous angular velocity is reached, the ignition timing is retarded even if the inflow air amount is increased, so that the phenomenon that the torque (output) increases at a stretch does not occur. For this reason, the phenomenon of racing is not generated, and in the case of a vehicle, there is no discomfort to the driver and passengers.

1 is a schematic diagram of an internal combustion engine according to an embodiment. It is a graph for demonstrating an effect | action.

(1) Description of Structure Next, an embodiment of the present invention will be described with reference to the drawings. First, the structure will be described with reference to FIG. FIG. 1 schematically shows the components of the internal combustion engine. The internal combustion engine of the present embodiment has three cylinders. Three cylinders 2 are formed in the cylinder block 1, and pistons 3 are slidably fitted in the respective cylinders 2. The reciprocating motion of each piston 3 is converted into the rotational motion of the crankshaft 5 via the connecting rod 4.

  A cylinder head 6 is overlapped and fixed to the cylinder block 1. An intake port 7 is opened for each cylinder 2 in the cylinder head 6, and an intake manifold 8 is fixed to each intake port 7. An intake passage 10 starting from an air cleaner 9 is connected to the intake manifold 8. An electronic throttle (slot valve) 11 and a surge tank 12 whose opening degree is electronically controlled are inserted in the intake passage 10. Yes.

  The electronic throttle 11 is disposed on the upstream side of the surge tank 12, and in this embodiment, an electronically controlled fuel injection pump 13 is provided in the surge tank 12 (the fuel injection pump 13 includes the intake manifold 8 and the It may be provided in each intake port 7). The cylinder head 2 is provided with a spark plug 14 corresponding to each cylinder 2. Actually, each cylinder head 2 is formed with a tapered recess (combustion chamber) opened to the cylinder, and a spark plug 14 is provided at the apex of the recess. Not displayed.

  The crankshaft 5 protrudes greatly from one side 1a of the cylinder block 1 and a sprocket 16 for driving the valve mechanism is fixed to the protruding portion, and a timing chain 17 is wound around the sprocket 16. The timing chain 17 is covered with a chain cover 18 from the outside, and a gear-like rotational speed detection rotor 19 is fixed to the outer side of the chain cover 18 of the crankshaft 5, and an accessory driving pulley 20 is provided on the outside thereof. It is fixed.

  A rotation sensor 21 is disposed on the outer surface of the chain cover 18 so as to face the outer periphery of the rotation speed detection rotor 19. By detecting the teeth (protrusions) of the rotation speed detection rotor 19 with the rotation sensor 21, the angular velocity can be detected finely. That is, since the piston 3 moves downward while decelerating in the explosion stroke, the angular speed (the number of revolutions or the peripheral speed) of the crankshaft 5 changes when viewed in detail, but the instantaneous angular speed of the crankshaft 5 changes. Can be detected by the rotation sensor 21.

  The rotational speed detection rotor 19 is provided with an origin portion by increasing the width of the teeth or increasing the groove width of the notch. Therefore, the rotation posture of the crankshaft 5 and the reciprocation of each piston 3 are provided. The relationship with the moving position can be grasped. As a result, it is possible to control the spark plug 14 and the valve timing.

  The internal combustion engine includes an ECU (engine control unit) 22 as control means, and the rotation sensor 21, each spark plug 14, the electronic throttle 11, and the fuel injection pump 13 are electrically connected to the ECU 22. Therefore, it goes without saying that the ECU 22 is responsible for controlling the ignition timing of the spark plug 14, controlling the opening of the electronic throttle 11, and controlling the fuel injection timing and fuel injection amount by the fuel injection pump 13.

(2). Control Mode Next, a control mode during idling will be described with reference to FIG. Control of the rotational speed at idling is basically performed by feedback control that brings the actual rotational speed close to the target rotational speed. For example, foreign matter enters the intake passage and bites into the valve of the electronic throttle 11. Due to the external factors, the instantaneous angular velocity may drop rapidly. For this reason, if idling is set to a value close to the limit, engine stall may occur. Therefore, the instantaneous angular velocity is always monitored in the idling state, and when the instantaneous peak angular velocity drops to the set value, the engine stall prevention control is executed in a manner that interrupts the feedback control.

  In FIG. 2A, the rotational fluctuation (angular speed fluctuation) of the crankshaft 5 is displayed. Since the internal combustion engine of the present embodiment is a four-cycle three-cylinder, the explosion stroke is the rotational angle of the crankshaft 5 every 270 °. Get up. For this reason, a peak appears in the angular velocity of the crankshaft 5 at a cycle of 270 °. That is, the cycle is repeated in which the angular velocity decreases rapidly from the peak (near top dead center), continues in a low steady state, and then increases rapidly toward the peak.

  The instantaneous peak angular velocity R0 that can stably maintain the idling state is set as the safe instantaneous peak angular velocity R0, and the instantaneous peak angular velocity that is likely to cause misfire as it is is set as the misfire prevention instantaneous peak angular velocity R1. A misfire-predictive instantaneous peak angular velocity R2 is set as an instantaneous peak angular velocity between the peak angular velocity R0 and the misfire prevention instantaneous peak angular velocity R1. R2 may be a numerical value approximately between R0 and R1, or may be a numerical value closer to R0 or R1.

  FIGS. 2B and 2C show the electronic throttle 11 and the ignition timing in a state where the instantaneous peak angular velocity of the engine is stable in the vicinity of the safe instantaneous peak angular velocity R0. The throttle opening is Q0, the ignition timing is neither retarded nor advanced from the reference point, and the deviation angle from the reference point is zero. The reference point of the ignition timing can be a position where the piston 3 is slightly lowered from the top dead center, for example.

  When the instantaneous peak angular velocity is lowered to a position lower than R2 and higher than R2 as indicated by a dotted line in FIG. 2A, the opening degree of the electronic throttle 11 is changed to Q as shown in FIGS. The amount of inflow air is increased by Q 'from Q0 to Q1, and the ignition timing is retarded by a slight angle t from the reference position. Thereby, it is possible to maintain a state in which the actual torque is not increased while maintaining the increased torque standby state in which the inflow air amount is increased. Therefore, the increase amount of the inflowing air amount and the retardation amount of the ignition timing must be set so as to hardly cause torque fluctuation (if the inflowing air amount is excessively increased, the ignition timing is retarded). However, the torque will rise rapidly.)

  When the instantaneous peak angular velocity rises above the misfire-predictive instantaneous peak angular velocity R0 due to the increase of the inflow air amount and the retard of the ignition timing, the electronic throttle 11 is returned to Q0 after the elapse of a preset time, and the ignition timing is changed. Return to the reference point. The elapsed time may be fixed, such as how many seconds, or may be variable. In the case of the variable type, for example, according to the frequency at which the misfire-predictor instantaneous peak angular velocity R2 appears, it is possible to set the elapsed time to be longer when the appearance frequency per unit time is high. The return mode of the inflow air amount and the ignition timing may be returned at once, or may be returned in several steps.

  For example, when the instantaneous peak angular velocity is lower than R1 at the fourth peak in (A), the ignition timing is advanced by t ′ from the reference point while maintaining the inflowing air amount Q2. Thereby, a torque can be raised instantaneously and an engine stall can be prevented. Even if the ignition timing is returned to the reference point, the torque increases, but if the angle is further advanced than the reference as in the embodiment, the torque increasing effect is remarkably exhibited. Even if the ignition timing is advanced, ignition is not performed in a state where the piston 3 is positioned before the top dead center.

  When the instantaneous peak angular velocity returns to the safe instantaneous peak angular velocity R1 by increasing the torque (that is, the rotational speed increases), after a certain amount of elapsed time (for example, several seconds) has elapsed, the inflow air amount is returned to Q0 and the spark plug 14 is returned to the reference point. Also in this case, the elapsed time may be fixed or variable.

  When the instantaneous peak angular velocity is repeatedly reduced, the safe instantaneous peak angular velocity R0, the misfire-predictive instantaneous peak angular velocity R2, and the misfire-preventing instantaneous peak angular velocity R1 can be increased. That is, in the present invention, the safe instantaneous peak angular velocity R0, the misfire-predictive instantaneous peak angular velocity R2, and the misfire-preventing instantaneous peak angular velocity R1 do not have to be fixed, and can be changed according to the actual operating state. It is also possible to change the idling rotation target value of feedback control based on the appearance rate of the misfire precursor instantaneous peak angular velocity.

  In the above embodiment, the safe instantaneous angular velocity, the misfire-predictive instantaneous angular velocity, and the misfire-preventing instantaneous angular velocity are based on the instantaneous peak angular velocity, but are fixed based on the instantaneous bottom angular velocity or the number of times from the top dead center. It is also possible to use the instantaneous angular velocity of the rotational position as a reference.

  The present invention is actually applicable to an internal combustion engine. Therefore, it can be used industrially.

DESCRIPTION OF SYMBOLS 1 Cylinder block 3 Piston 5 Crankshaft 6 Cylinder head 8 Intake manifold 10 Intake passage 11 Electronic throttle 13 Fuel injection pump 14 Spark plug 19 Rotation speed detection rotor 21 Rotation sensor 22 ECU

Claims (1)

A rotation sensor capable of finely detecting the angular velocity of the crankshaft, an electronic throttle capable of arbitrarily controlling the amount of air flowing into the cylinder, an ignition plug, and the electronic throttle and the ignition plug based on a signal from the rotation sensor And a control means,
An instantaneous angular velocity lower than a safe instantaneous angular velocity that does not cause a stall and higher than a misfire preventing instantaneous angular velocity for preventing a stall is set in advance as a misfire-predictive instantaneous angular velocity, and by the control means,
1) As a reference step, when the instantaneous angular velocity detected by the rotation sensor is lower than the misfire sign instantaneous angular velocity and higher than the misfire prevention instantaneous angular velocity, the inflow air amount is increased by the electronic throttle and the ignition timing is retarded. To
2) If the instantaneous angular velocity detected by the rotation sensor after the reference step exceeds the misfire-predictive instantaneous angular velocity, then return the inflow air amount and the ignition timing.
3) If the instantaneous angular velocity detected by the rotation sensor after the reference step is lower than the misfire prevention instantaneous angular velocity, the ignition timing is advanced to a state before the reference step or higher.
Control is made,
Internal combustion engine.

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