JPH0351903B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine ignition timing control device that controls ignition timing in each cylinder of an engine according to the operating state of the engine.

(Prior Art) Conventionally, as a technology related to engines installed in automobiles, etc., for example, when the engine speed is above a predetermined value and the throttle valve linked to the accelerator pedal is in a substantially fully closed state (idling opening state), ), the fuel supply is stopped, so-called deceleration fuel cut, and when the engine speed becomes less than a predetermined value after such deceleration fuel cut, or when the throttle valve is opened from a substantially fully closed state, the fuel supply is stopped. It is known to improve fuel efficiency and reduce harmful components contained in exhaust gas by restarting the supply of fuel, so-called fuel restoration.

Further, in connection with an engine in which deceleration fuel cut is performed under operating conditions that satisfy predetermined conditions, and then fuel restoration is performed,
For example, as shown in Japanese Unexamined Patent Publication No. 55-25594, a device is attached to such an engine to shift the ignition timing set according to the engine operating state to the delayed side when the fuel is restored. Accordingly, an ignition timing control device has been proposed which aims to reduce the torque shock when the fuel is restored.

(Problems to be Solved by the Invention) However, in an engine in which the deceleration fuel is cut and the fuel is then returned as described above, when the deceleration fuel is cut off, the fuel adheres to and remains in the intake passage. A portion of the fuel supplied before the deceleration fuel is cut will evaporate, but the air-fuel mixture formed by this evaporated fuel will not be exhausted in the combustion chamber and will be discharged to the exhaust passage and will remain in the exhaust passage. However, when the fuel is subsequently restored, the unburnt air-fuel mixture remaining in the exhaust passage is ignited by the high-temperature combustion gas that is burned in the combustion chamber and discharged to the exhaust passage, causing rapid combustion in the exhaust passage, resulting in so-called , there is a risk that afterburn will occur. The occurrence of such afterburn not only reduces the operating performance of the engine, but also causes problems in that it reduces the durability of various parts forming the exhaust system of the engine.

In view of these points, the present invention is designed to improve fuel efficiency and purify exhaust gas by cutting fuel for deceleration and then returning the fuel under operating conditions that satisfy predetermined conditions. This device is attached to the engine, and by shifting the ignition timing at the time of fuel recovery to the advance side from the normal ignition timing set according to the engine operating condition, a part of the fuel supplied before the deceleration fuel is cut is left unburned. An object of the present invention is to provide an ignition timing control device for an engine that can suppress afterburn that occurs when fuel is returned due to the mixture remaining in an exhaust passage.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the engine ignition timing control device according to the present invention, as shown in the basic configuration in FIG. A driving state detecting means, which is provided in the engine to which fuel supply is stopped when the state satisfies a predetermined condition, detects the operating state thereof, and an ignition timing of the engine is set based on a detection output from the operating state detecting means. ignition timing setting means; and when fuel supply to the engine is stopped by the fuel supply control means and then restarted, ignition is set by the ignition timing setting means for a predetermined period based on a detection output from the operating state detection means; The ignition timing correction means is configured to perform control to shift the ignition timing to the advanced side by an amount that increases as the period during which fuel supply is stopped is increased.

(Function) In the engine ignition timing control device according to the present invention configured as described above, the fuel supply to the engine is stopped by the action of the fuel supply control means, and when the fuel supply is restarted thereafter, the fuel Resumption of supply, ie, return of fuel, is detected by the operating state detection means. When the fuel is restored, the ignition timing correction means adjusts the ignition timing set by the ignition timing setting means for a predetermined period based on the detection output obtained from the operating state detection means during the period during which the fuel supply was stopped. The shorter the value, the larger the amount of transition, and the transition is made to the advance side. As a result, during a predetermined period when the fuel is restored, the combustion temperature of the air-fuel mixture combusted in the cylinders of the engine is lowered, and the temperature of the combustion gas discharged into the exhaust passage becomes relatively low.As a result, the fuel Even if unburned air-fuel mixture remains in the exhaust passage when supply is stopped, the occurrence of afterburn can be avoided, and when fuel is restored, the air-fuel ratio changes due to the influence of unburned fuel adhering to the intake passage. The ignition timing is set to take an advance value corresponding to the combustion temperature, and combustion temperature can be managed more accurately.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 shows an example of an engine ignition timing control device according to the present invention, together with the main parts of an engine to which the device is applied.

In FIG. 2, an engine body 10 consisting of a cylinder head 11 and a cylinder block 13 is provided with a cylinder 14. A piston 16 is fitted into the cylinder 14, and a piston 16 is inserted into the cylinder 14 through an intake valve 18 and an exhaust valve 19. An intake passage 20 and an exhaust passage 22 are connected to each other. Also, inside the cylinder 14 are a cylinder head 11, a cylinder block 13,
A combustion chamber 24 is formed surrounded by the piston 16, the intake valve 18, the exhaust valve 19, etc.
A spark plug 26 is provided temporarily.

The intake passage 20 includes, from the upstream side, an air filter 28 that purifies intake air, an air flow meter 30 that detects the amount of intake air, a throttle valve 32 that opens and closes the intake passage 20 in conjunction with the accelerator pedal, and a throttle valve 32 that opens and closes the intake passage 20 in conjunction with the accelerator pedal. An idle switch 34 that is turned on when the valve is in a substantially fully closed state (idling opening state), and an intake negative pressure that detects the intake negative pressure (pressure inside the intake passage) in the downstream side of the throttle valve 32 in the intake passage 20. The sensor 35 and the fuel fed under pressure from the fuel supply section are connected to the intake passage 2.
Fuel injection valves 36 are respectively provided for injecting fuel toward an intake port portion forming a downstream portion of the engine. The exhaust passage 22 is sequentially provided with a catalytic converter 38 for purifying exhaust gas and a silencer 39 for muffling exhaust noise from the upstream side.

Further, a distributor 44 whose rotating shaft is rotationally driven by the crankshaft is attached to the engine body 10. A rotation speed sensor 46 is provided to detect the engine rotation speed. An ignition coil section 42 that is integrated with the ignition timing control section 40 is connected to the distributor 44 .

Furthermore, in addition to this configuration, a control unit 100 is provided for controlling the ignition timing by the spark plug 26 and the fuel injection by the fuel injection valve 36, respectively.

The control unit 100 receives a detection signal Sa corresponding to the amount of intake air obtained from the air flow meter 30 and a detection signal St corresponding to the open/closed state of the throttle valve 32 obtained from the idle switch 34.
and the intake negative pressure obtained from the intake negative pressure sensor 35,
Therefore, the detection signal Sb according to the engine load,
A detection signal Sn corresponding to the engine rotation speed obtained from the rotation speed sensor 46 is supplied.

The control unit 100 calculates the fuel injection amount based on the detection signal Sa and the detection signal Sn out of the various detection signals described above, and generates an injection pulse signal having a pulse width corresponding to the calculated fuel injection amount.
Cp is formed and supplied to the fuel injection valve 36 at a predetermined timing. At the same time, based on the detection signal Sn and the detection signal St, a deceleration operation state in which the engine rotation speed is equal to or higher than a predetermined rotation speed and the throttle valve 32 is in a substantially fully closed state is detected, and the deceleration operation is performed. Fuel injection valve 36 in the state
The fuel supply to the engine is stopped by stopping the supply of the injection pulse signal Cp to the engine, that is, the deceleration fuel is cut off, and then, based on the detection signal Sn, a state in which the engine rotation speed is lower than a predetermined value is detected and A transition from a substantially fully closed state to an open state in the throttle valve 32 is detected based on the detection signal St, and when any of these is detected, an injection pulse signal is sent to the fuel injection valve 36.
By restarting the supply of Cp, the fuel supply to the engine is restarted, that is, the fuel is restored.

Furthermore, the control unit 100 sets the ignition timing (normal ignition timing) according to the operating state of the engine based on the detection signal Sn and the detection signal Sb, that is, based on the engine rotation speed and the engine load. The ignition control signal Cq corresponding to this normal ignition timing is supplied to the ignition timing control section 40, and when fuel is restored after deceleration fuel cut is performed, that is, at the time of fuel restoration, During a predetermined period after the fuel return is started, an ignition timing corrected to shift the above-mentioned normal ignition timing to the advanced side (corrected ignition timing) is set,
The ignition control signal Cq is changed to correspond to this corrected ignition timing and is supplied to the ignition timing control section 40. The ignition timing control section 40 controls the timing of the secondary side high voltage pulse obtained from the ignition coil section 42 based on the ignition control signal Cq from the control unit 100.
A secondary high voltage pulse obtained from the ignition coil unit 42 and having a timing corresponding to the ignition control signal Cq is supplied to the ignition plug 26 via the distributor 44. As a result, the ignition timing by the ignition plug 26 is made to correspond to the ignition control signal Cq, and the ignition plug 26 emits a spark in accordance with the normal ignition timing or corrected ignition timing set by the control unit 100, and the ignition timing is set in the combustion chamber 24. ignite the mixture.

Control unit 1 that performs control as described above
00 is configured using, for example, a microcomputer, and an example of a program executed by the microcomputer in such a case will be described with reference to the flowchart shown in FIG.

This program starts when the engine is started, and after the start, initial settings are performed in process 101, and the detection signals Sa, St, Sb and
Process 1 that reads the content represented by Sn and continues
In step 02, the normal ignition timing is set based on the engine rotational speed N represented by the detection signal Sn and the intake negative pressure (engine load) represented by the detection signal Sb. This normal ignition timing setting is based on the ignition timing control map related to the engine speed and intake negative pressure and the engine speed at that time, as shown equivalently in FIG. 4, which is stored in the built-in memory. This is done by comparing N and intake negative pressure and setting the ignition advance value θig corresponding to the engine speed N and intake negative pressure at that time.

Next, the process proceeds to decision 103, where the detection signal St
Based on this, it is determined whether the idle switch 34 is in the on state, that is, whether or not the throttle valve 32 is in the substantially fully closed state. move on. In decision 104, it is determined whether or not the engine rotational speed N at that time is equal to or greater than a predetermined value No. If it is determined that it is equal to or greater than the predetermined value No, the process proceeds to process 105 to stop fuel injection control. As a result, the supply of the injection pulse signal Cp to the fuel injection valve 36 is stopped, the fuel supply to the engine is stopped, and deceleration fuel cut is performed.

Next, in decision 106, it is determined whether the built-in timer I to measure the deceleration fuel cut period is measuring the deceleration fuel cut period (timer ON), and the timer I measures the deceleration fuel cut period. If it is determined that it is not, in process 107, timer I is made to start measurement (timer I is set), and the process proceeds to process 108.
On the other hand, if it is determined in decision 106 that timer I is measuring the deceleration fuel cut period, the process proceeds to process 108 without passing through process 107. Then, in process 108, the ignition advance value θig set in process 102 is
The ignition timing controller 4 generates an ignition control signal Cq that corresponds to the ignition timing controller 4.
Supply to 0 and return to normal.

Further, if the decision 103 determines that the idle switch 34 is not in the on state, that is, the accelerator pedal is depressed,
Proceeding to decision 109, it is determined whether or not a built-in timer is measuring the elapsed time to measure the elapsed time after the fuel is restored. The timer is
A predetermined time T _B is loaded in advance before the fuel is restored, and the remaining time is calculated as time passes after the fuel is restored.
It is said that measurements are performed to reduce T _B ′.
If it is determined in decision 109 that the timer is not measuring the elapsed time, the process proceeds to process 110 where the timer starts measuring (setting the timer), and the process proceeds to process 111. In process 111, the measurement time of the timer set in process 107, that is, the deceleration fuel cut period _TA , is read, and in the following process 112, the timer is returned to its initial state (the timer is reset), and the process proceeds to process 113. .

In process 113, the fuel injection amount is calculated based on the engine rotation speed N represented by the detection signal Sn and the intake air amount represented by the detection signal Sa,
An injection pulse signal Cp having a pulse width corresponding to the calculated fuel injection amount is formed and supplied to the fuel injection valve 36. As a result, an amount of fuel corresponding to the operating state of the engine is injected from the fuel injection valve 36, fuel is supplied to the engine, and fuel injection control is performed. Subsequently, process 108
Then, in the same manner as described above, the ignition control signal Cq corresponding to the ignition advance value θig set in process 102 is supplied to the ignition timing control section 40, and the process returns to the original state. As a result, the air-fuel mixture in the combustion chamber 24 is ignited and combusted, and the combustion gas is transferred to the exhaust passage 24.
2.

On the other hand, if it is determined in decision 109 that the timer is measuring the elapsed time, that is, that the predetermined time T _B has not yet elapsed after the fuel was restored, the remaining time T _B ' of the timer is read in process 114. After that, the process proceeds to process 115.
In process 115, a corrected advance value Δθ for shifting the normal ignition timing to the advance side is determined by Δθ=K・θ _A・
It is calculated based on the relationship θ _B (where K is a constant and θ _A and θ _B are correction values). Here, the correction value θ _A is assumed to take a smaller value as the deceleration fuel cut period T _A becomes longer, as shown equivalently in FIG. 5, and is stored in the built-in memory. , the one corresponding to the deceleration fuel cut period T _A read in process 111 is read out.
In addition, the correction value θ _B takes a smaller value as the remaining time T _B ' of the timer becomes shorter. The one corresponding to _B ′ is read out. Therefore, the correction advance value Δθ becomes larger as the deceleration fuel cut time _TA read in process 111 becomes shorter, and as the remaining time T _B ' of the timer read in process 111 becomes smaller, the correction advance value Δθ becomes larger. In other words,
It becomes smaller as time passes after the fuel is restored. The reason why the correction advance value Δθ is set to be smaller as the deceleration fuel cut period _TA is longer is that when the deceleration fuel cut period _TA is long, most of the fuel adhering to the intake passage 20 is This is because a relatively thin air-fuel mixture will be supplied to the combustion chamber 24 when the fuel is restored, and if the ignition timing is moved significantly to the advanced side, there is a risk that the engine will stop. In addition, the correction advance angle value Δθ is set to become smaller as the remaining time T _B ' of the timer becomes shorter, in order to alleviate the torque shock when the engine is brought back to normal operation after returning to fuel. It's for a reason.

After the corrected advance value Δθ is calculated as described above, in process 116, the corrected advance value Δθ calculated in process 115 is added to the ignition advance value θig set in process 102, and a new ignition is performed. The lead angle value θig is set, and then, in process 113, fuel injection control is performed in the same manner as described above. In this case, since the throttle valve 32 is in the open state after the deceleration fuel is cut, the fuel is returned in an accelerated state. next,
Proceeding to process 108, in process 108, the value corresponding to the ignition advance value θig, which represents the corrected ignition timing that is shifted to the advanced side by the corrected advance value Δθ from the normal ignition timing, is set in process 116. The ignition control signal Cq thus obtained is supplied to the ignition timing control section 40, and the process returns to the original state.

Further, if it is determined in the decision 104 that the engine rotation speed N at that time is not equal to or higher than the predetermined rotation speed No, the process proceeds to a process 112;
Hereinafter, as described above, processes 112,
The operations at 113 and 108 are performed in sequence, and the process returns to the beginning. In this case, the fuel will be restored during idling after deceleration fuel is cut, but in such a case, there is little risk of afterburn occurring, and the ignition timing can be shifted to the advanced side. Since there is a risk of non-negligible torque fluctuations caused by
This is performed in accordance with the ignition advance value θig, which is set as the normal ignition timing in step 02.

While fuel injection control and ignition timing control are being performed by the control unit 100 according to the program as described above, for example, the idle switch 34 operates as shown in FIG. 6A.
turned on (ON) and off (OFF),
Accordingly, if the engine speed N is changed as shown in FIG. 6B, the fuel injection amount and the ignition advance value θig,
It changes as shown in Figures C and D.

That is, if the throttle valve 32, which was open before time _t1 , is brought to a substantially fully closed state at time _t1 , and the idle switch 34 is accordingly turned on at time _t1 , then at time _t1 , The engine is transferred from a normal operating state to a deceleration operating state. At this time, since the engine speed N is greater than or equal to the predetermined value No, deceleration fuel cut is performed and the fuel injection amount is made zero. As a result, the engine speed N gradually decreases after time _t1 .

Then, at time _t2, the engine speed N is set to a predetermined value.
If the value is less than No, the fuel is restored, but in this case, as mentioned above, the fuel is restored during idling, so the ignition advance value is not corrected and the ignition timing is adjusted to match the engine speed N. This is the normal ignition timing set based on the intake negative pressure. Next, at time _t3 , the throttle valve 32 is opened.
When the idle switch 34 is switched from the on state to the off state, the engine speed N, the fuel injection amount, and the ignition advance value are all increased.

Subsequently, at time _t4 , the throttle valve 32 is again brought into a substantially fully closed state, the idle switch 34 is turned on, and the engine is shifted to a deceleration operating state. No
Because of the above, deceleration fuel cut is performed and the fuel injection amount is made zero. This deceleration fuel cut continues until time _t5 when the throttle valve 32 is then opened and the idle switch 34 is turned off, and the deceleration fuel cut period _TA at this time is the time _t4.
to time t ₅ . Then, at time _t5 , the throttle valve 32 is depressed, the idle switch 34 is switched from the on state to the off state, and the fuel is restored under the acceleration state. At this time, during the period from time t ₅ to time t ₆ when the predetermined time T _B loaded into the timer has elapsed, the ignition advance value θig is set as the normal ignition timing based on the engine speed N and intake negative pressure. The ignition advance value is corrected by adding the corrected advance value Δθ to the ignition timing.
The corrected ignition timing is shifted to the advanced side from the normal ignition timing, which is set based on the engine speed N and the intake negative pressure. At that time, the deceleration fuel cut time T _A
The shorter the remaining time T _B ′ of the timer, the longer the ignition advance value θig (6th
The corrected advance angle value Δθ (shown with hatching in FIG. 6D) added to the lead angle value Δθ (shown with a hatched line in FIG. 6D) is set to be large. Therefore, during the period from time _t5 , which is the fuel return point, to time _t6 , at which the predetermined time T _B has elapsed, the ignition timing is moved to the advance side of the normal ignition timing, and the ignition timing is shifted to the advance side. The amount will be gradually reduced.

In this way, when fuel is restored under accelerated driving conditions after deceleration fuel is cut,
By shifting the ignition timing to the advanced side from the normal ignition timing, the temperature of the combustion gas discharged into the exhaust passage 22 when the fuel is restored is lowered, and as a result, the unburned air-fuel mixture remaining in the exhaust passage 22 is combusted. The occurrence of afterburn, where gas ignites and causes rapid combustion, can be avoided.

(Effects of the Invention) As is clear from the above description, according to the engine ignition timing control device according to the present invention, deceleration fuel cut and subsequent fuel return are performed in order to improve fuel efficiency and promote exhaust gas purification. In engines where deceleration fuel cut is performed, the normal ignition timing, which is set according to the operating state of the engine, is corrected for a predetermined period corresponding to the time of fuel restoration, and the shorter the period in which deceleration fuel was performed, the greater the Therefore, the temperature of the exhaust gas discharged into the exhaust passage immediately after the fuel is restored is lowered, and therefore, the unburned mixture discharged into the exhaust passage when the deceleration fuel is cut is Even if Qi stagnates, the occurrence of afterburn is effectively suppressed, and
The ignition timing is set to take an advance value that corresponds to the change in the air-fuel ratio due to the influence of unburned fuel adhering to the intake passage when the fuel is restored, so that combustion temperature can be managed more accurately. Therefore, in an engine to which the engine ignition timing control device according to the present invention is applied, which performs deceleration fuel cut and subsequent fuel return, the operational performance is improved, and in particular, the engine ignition timing control device of the present invention is improved. This will prevent the durability of each part from decreasing.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of an engine ignition timing control device according to the present invention in accordance with the claims, and FIG. 2 is a diagram showing an example of the engine ignition timing control device according to the present invention to which it is applied. FIG. 3 is a schematic configuration diagram shown together with the engine shown in FIG. FIG. 5 is a diagram used to explain the operation of the example shown in FIG. 2, and FIG. 6 is a time chart used to explain the operation of the example shown in FIG. In the figure, 20 is an intake passage, 22 is an exhaust passage, 26
is a spark plug, 30 is an air flow meter, 34 is an idle switch, 35 is an intake negative pressure sensor, 36
40 is a fuel injection valve, 40 is an ignition timing control section, 42 is an ignition coil section, 44 is a distributor, 46 is a rotational speed sensor, and 100 is a control unit.

Claims (1)

[Scope of Claims] 1. Operating state detection means for detecting the operating state of an engine which is provided with a fuel supply control means and stops the fuel supply when the operating state satisfies a predetermined condition by the fuel supply control means; ignition timing setting means for setting the ignition timing of the engine based on a detection output obtained from the operating state detecting means; and when fuel supply to the engine is stopped by the fuel supply control means and then resumed, the operating state Based on the detection output obtained from the detection means, the ignition timing is set by the ignition timing setting means for a predetermined period with a shift amount that is larger as the period during which the fuel supply is stopped is shorter; An ignition timing control device for an engine, comprising: ignition timing correction means for performing control to shift the ignition timing to the advance side;