JP6057745B2 - Internal combustion engine - Google Patents

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, Patent Document 1 increases the inflow air amount after the actual instantaneous peak angular velocity has decreased to the misfire prevention instantaneous peak angular velocity. There is a risk of engine 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.

Further, switching from the feedback control to the open control causes a phenomenon that the engine speed increases at a stretch and becomes a state of being blown away , 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, a rotation sensor capable test known angular velocity of the crankshaft, an electronic throttle that can arbitrarily control the inflow air quantity into the cylinder, a spark plug, the electronic throttle on the basis of a signal from the rotation sensor And a control means for controlling the spark plug (the fuel injection amount is calculated according to the air amount, and when the inflow air amount increases or decreases, the fuel injection amount also increases or 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) Before Symbol detects the instantaneous angular velocity at the start of control by the rotation sensor, when the instantaneous angular velocity at the control start said misfire indication instantaneous angular velocity flame-out prevention instantaneous angular velocity by Ri have higher lower than the inflow air quantity control start causing retarded than at the start of control of the ignition timing causes increase than performs reference steps of,
2) After exceeding the instantaneous angular speed detected by the rotation sensor after the reference step misfire indication instantaneous angular velocity, return inlet air quantity and the ignition timing flow to the state it was in when the control start,
3) When less than the rotation sensor instantaneous angular velocity the flame-out prevention instantaneous angular velocity detected by the after the reference step, is advanced from the ignition timing state when the control starting condition to return or control start,
Control is made.

In the step of returning the inflow air amount and the ignition timing to the state at the start of control when the instantaneous angular velocity detected by the rotation sensor after the reference step exceeds the misfire indication instantaneous angular velocity, the step immediately returns when the misfire indication instantaneous angular velocity is exceeded. it is also possible, in anticipation of safety, preferred state exceeds the misfire indication instantaneous angular velocity that to back or we passed the preset time. The same applies to the return control after the instantaneous angular velocity is lower than the misfiring 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 misfiring prevention instantaneous angular velocity, misfire is predicted and the inflow air amount is increased in advance, and preparations for increasing the torque are made. reaches the flame-out prevention instantaneous angular speed, can increase torque to immediately seat 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. For this reason, the rotational 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, allows the control of the control and the valve timing of the spark plug 14.

  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 Q1 , 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. Q0 is a state where the opening degree is zero.

During control start, but the throttle opening is Q1, instantaneous peak angular velocity, as indicated by a dotted line in FIG. 2 (A), when being lowered to a position higher than R1 lower than R0, 2 ( D) As shown in (E), as a reference step, the throttle opening is increased by Q ' from Q1 at the start of control to increase the inflow air amount , and the ignition timing is slightly increased from that at the start of control . The angle is delayed by the angle t. As a result, it is possible to maintain a state in which the actual torque is not increased while maintaining the torque increase standby state in which the inflow air amount is increased. Therefore, it is necessary to set the increase amount of the inflow air amount and the retard amount of the ignition timing so that the torque fluctuation hardly occurs (if the inflow 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 throttle opening is set to the reference Q1 at the start of control after waiting for the elapse of a preset elapsed time. At the same time, the ignition timing is returned to a reference point with no advance or delay at the start of control . 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, if the instantaneous peak velocity in the fourth peak of (A) is lower than R1 is while maintaining the slot torr opening in Q2, t 'is only advanced from the reference point of the ignition timing. 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 R0 due to the torque increase (that is, the rotational speed increases), after a certain amount of elapsed time (for example, several seconds) has passed, the throttle opening is returned to Q1 and the ignition timing Return 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 for the angular speed of the crankshaft can test knowledge, control for controlling the electronic throttle that can arbitrarily control the inflow air quantity into the cylinder, a spark plug, the electronic throttle and the ignition plug based on a signal from the rotation sensor And a means comprising
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) Before Symbol detects the instantaneous angular velocity at the start of control by the rotation sensor, when the instantaneous angular velocity at the control start said misfire indication instantaneous angular velocity flame-out prevention instantaneous angular velocity by Ri have higher lower than the inflow air quantity control start causing retarded than at the start of control of the ignition timing causes increase than performs reference steps of,
2) After exceeding the instantaneous angular speed detected by the rotation sensor after the reference step misfire indication instantaneous angular velocity, return inlet air quantity and the ignition timing flow to the state it was in when the control start,
3) When less than the rotation sensor instantaneous angular velocity the flame-out prevention instantaneous angular velocity detected by the after the reference step, is advanced from the ignition timing state when the control starting condition to return or control start,
Control is made,
Internal combustion engine.

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