JPH0726565B2 - Engine fuel supply controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an engine fuel supply control device, and more particularly to a fuel supply control during engine transient operation when engine combustion is controlled to reduce engine vibration. Regarding the improvement of.

(Prior Art) Conventionally, as a technology for reducing engine vibration, as disclosed in, for example, Japanese Patent Laid-Open No. 56-146025, a roughness sensor for detecting the instability of engine combustion (so-called roughness) An engine having combustion instability (hereinafter referred to as roughness) exceeding a predetermined value, provided with combustion adjusting means for controlling combustion of the engine by increasing / decreasing adjustment of fuel supply amount, retarding ignition timing of spark plug, adjusting advance angle, etc. When the vibration is large, the fuel supply amount is corrected and increased by the combustion adjusting means, or the roughness control is performed so as to advance the ignition timing of the spark plug to stabilize the combustion state of the engine, so that the roughness is always set to a predetermined value. It is known that the engine vibration is effectively reduced by keeping the value below the value.

(Problems to be Solved by the Invention) By the way, when the operating state of the engine shifts from a steady operating state to a transient state of decelerating operation or accelerating operation, the fuel supply to the engine normally depends on the combustion state of the engine. When the combustion state in the steady operation state is unstable, the amount of fuel increase is large, for example, during acceleration transient, and conversely, when the combustion state in the steady operation state is stable, the amount of fuel increase is small. It is a thing.

However, in an engine that aims to reduce vibration by the roughness control as described above, if the engine is originally in an unstable combustion state, the combustion state is accelerated because the combustion state is stably maintained by the roughness control. The amount of fuel increase during transition is small, so during engine transient operation where roughness control does not follow, the amount of fuel increase corresponding to the roughness cannot be obtained, and the original combustion instability is exposed and rattling occurs during acceleration. . Similarly, in an engine that cuts fuel during a deceleration transition, the fuel supply is restored at a predetermined engine speed in the vicinity of the idle region, but if the engine has low combustion stability, the misfire limit margin is low. A defect that tends to cause a stop occurs, and drivability is deteriorated.

The present invention has been made in view of such a point, and an object thereof is to increase the amount of fuel supply during acceleration transient of the engine or to supply fuel during deceleration transient in an engine that performs the roughness control as described above. The correction conditions for the fuel supply to the engine, such as the number of revolutions, are not fixed to a predetermined value, but are changed according to the correction amount of the combustion state by the roughness control, so that the fuel correction conditions can be changed to the engine characteristics even during an engine transient. Correspondingly, for example, it is possible to effectively prevent the rattling in the acceleration transient and the engine stall in the deceleration transient to improve the drivability.

(Means for Solving Problems) In order to achieve the above object, the solution means of the present invention detects the instability of combustion of an engine that performs roughness control, that is, the engine 1, as shown in FIG. Combustion instability detection means 50 and combustion adjustment means 11 for adjusting combustion of the engine 1
And a control means 51 for controlling the combustion adjustment means 11 so that the combustion instability detected by the combustion instability detection means 50 becomes a predetermined value or less, and an engine for reducing vibration Is assumed. Then, the fuel correction means 52 that performs fuel correction for the engine 1 during transient operation of the engine 1 and the fuel correction condition of the fuel correction means 52 are set to the correction amount based on the combustion instability of the combustion adjustment means 11. The correction condition changing means 53 that is changed accordingly is provided.

(Operation) According to the present invention, in the present invention, when the roughness of the engine 1 exceeds a predetermined value, the control means 51 controls the operation of the combustion adjusting means 11 to stabilize the combustion state of the engine 1. It becomes smaller and is maintained below a predetermined value at all times, and the vibration of the engine 1 is favorably reduced.

Now, when the engine operating state shifts to the transient state, the roughness control is delayed, and the engine 1 shows the feature of its combustion stability. In this case, the fuel correction condition of the engine 1 is changed by the correction condition changing means 53, and the correction amount of the roughness control is large in an engine having low combustion stability. Therefore, for example, the fuel increase amount is adjusted a lot during acceleration. During the deceleration transition, the fuel return rotational speed after the fuel cut is corrected to a high value, the acceleration wobbling and the engine stall are effectively prevented, and the drivability is improved.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

In FIG. 2, reference numeral 1 is an engine, 2 is a combustion chamber whose volume is formed by a piston 4 slidably fitted in a cylinder 3 of the engine 1, and 5 is connected to the atmosphere through an air cleaner 6 at one end. The other end communicates with the combustion chamber 2 to supply intake air to the engine 1. The intake passage 7 has one end communicating with the combustion chamber 2 and the other end open to the atmosphere for discharging exhaust gas. A throttle valve 10 for controlling the intake air amount in the middle of the intake passage 5, which is an exhaust passage, and a combustion adjustment for injecting and supplying fuel downstream of the throttle valve 10 to adjust the combustion state of the engine 1. Fuel injection valve as a means 11
And an intake valve 12 at the opening of the intake passage 5 to the combustion chamber 2. on the other hand,
An exhaust valve 13 is provided at the opening of the exhaust passage 7 to the combustion chamber 2, and a catalyst device 14 is provided in the middle of the exhaust passage 7.

Reference numeral 15 is an intake air temperature sensor arranged in the air cleaner 6 for detecting the temperature of intake air, 16 is an air flow sensor for detecting the amount of intake air on the upstream side of the throttle valve 10, and 17 is the opening of the throttle valve 10. Opening sensor, 18 a water temperature sensor for detecting the engine cooling water temperature, 19 an exhaust passage 7
The air-fuel ratio sensor for detecting the air-fuel ratio of the air-fuel mixture based on the oxygen concentration component of the exhaust gas on the upstream side of the catalyst device 14, 20 is a distributor as a rotation speed sensor for detecting the engine speed, and each of the sensors 15- The detection signals of 20 are respectively inputted to the controller 21, and the controller 21 adjusts the fuel injection amount from the fuel injection valve 11 in accordance with the operating condition of the engine 1 to adjust and control the fuel condition of the engine 1. I am trying. In the figure, 22 is an igniter and 23 is a vehicle battery.

Next, the internal structure of the controller 21 is shown in FIG. In the figure, 30 receives the intake air amount T _P signal from the air flow sensor 16 and multiplies the intake air amount T _P by an injection pulse width conversion coefficient C _K to obtain a basic pulse width corresponding to the intake air amount T _P. A basic pulse width calculation circuit for calculating (T _P × C _K ), 31 is a high load increase correction coefficient C _EN according to the intake air amount T _P signal from the air flow sensor 16 and the engine speed Ne signal from the distributor 20. Is read from an internal map, 32 is an acceleration correction circuit that calculates an acceleration correction coefficient C _A in accordance with the change in the throttle opening signal from the throttle opening sensor 17, and 33 is the throttle opening sensor as well. An asynchronous pulse width calculation circuit that calculates the asynchronous pulse width during acceleration according to the change in the throttle opening signal from 17 and 34 is the engine speed Ne signal from the distributor 20 and the throttle opening sensor 17 Current engine operating condition at the time of deceleration in accordance with the Le opening signal is the basic fuel cut region determining circuit determines whether there the basic fuel cut region.

35 is the engine speed from the distributor 20.
Rotation fluctuation width calculation circuit that calculates the rotation fluctuation width ΔN _E of Ne, 36
Is a comparator that compares the rotation fluctuation width ΔN _E of the rotation fluctuation width calculation circuit 35 with the reference value N ₁ of the reference value setting circuit 37, and outputs a roughness correction command signal when ΔN _E > N ₁ , 38 is the comparator The roughness correction coefficient C is received in response to the roughness correction command signal from the comparator 36.
_This is a roughness correction circuit that corrects the _RO value.

Further, 39 is a first addition circuit for adding the roughness correction coefficient C _RO of the roughness correction circuit 38 and the acceleration correction coefficient C _A of the acceleration correction circuit 32, and 40 is a coefficient value (C _RO + C _A ) and a high load increase correction coefficient C _{EN of the} load correction circuit 31 are added together by a second adder circuit 41 is provided by the second adder circuit 4
_A multiplier for increasing the basic pulse width (T _P × C _K ) of the basic pulse width arithmetic circuit 30 by the coefficient value (C _RO + _CA + C _EN ) obtained at 0, which is obtained by the multiplier 41. Coefficient value {T _P × C _K
× while being converted into _{(1 + C RO + C A} + C EN)} is the last pulse width T _I in the last pulse width setting circuit 42 sets an asynchronous pulse width computed asynchronously pulse width above asynchronous pulse width computing circuit 33 It is output to the fuel injection valve 11 via the driver 44 at different times together with the asynchronous pulse width of the asynchronous pulse width setting circuit 43.

In addition, 45 is a final fuel cut area determination circuit that determines the final fuel cut area by correcting the basic fuel cut area of the basic fuel cut area determination circuit 34 based on the roughness correction command signal from the comparator 36. .

Next, the operation of the controller 21 will be described with reference to the flowchart of FIG. After starting, in step S ₁ , the intake air amount T _P signal from the air flow sensor 16, the engine speed Ne signal from the distributor 20, and the throttle opening signal Th from the throttle opening sensor 17 are input, and then the step In S ₂ , the load correction circuit 31 calculates the high load increase correction coefficient C _EN .

Thereafter, it is determined whether or not the current engine operation state grasped from the engine speed Ne and the throttle opening Th is in the roughness control region excluding the high-load range, etc. In step S _3, in roughness control region If YES, step S
_{In step 4} , the rotational fluctuation width calculation circuit 35 calculates the rotational fluctuation width ΔN _E of the engine speed Ne, and in step S ₅ , the reference value N ₁ of the rotational fluctuation width corresponding to the unstable combustion state of the engine is set as the intake air amount. After the calculation based on T _P and the engine speed Ne, the comparator 36 compares the rotation fluctuation width ΔN _E with the reference value N ₁ in step S ₆ , and when N _E > N ₁ is YES when combustion is unstable In this case, in order to improve the combustion stability, a small value C ₁ is added to the roughness correction coefficient C _RO in step S ₇ , while in the case of combustion stabilization of NO of ΔN _E ≦ N ₁ ,
Subtracting the minute value C ₁ from the roughness correction coefficient C _RO reversed S _8.

Then, the roughness correction coefficient C _RO (low margin to misfire limit) combustion stability of low engine compares the magnitude and the reference value C ₂ corresponding to the time at step S _9, the combustion stability of C _RO> C ₂ when sex of low, minute value from the fuel cut at the time of deceleration operation in step S ₁₀ the restoration speed N _REC to return the fuel supply
While adding N ₂ to increase the return speed N _REC ,
If the combustion stability of NO for C _RO ≤ C ₂ is good, first, in step S ₁₁ , the return speed N _REC is compared with the reference return speed N _RECO, and if N _REC > N _RECO is YES, _{Reduces the} return speed N _REC by subtracting a small value N ₂ from the return speed N _REC , while in case of NO of N _REC ≤ N _RECO , this reference return N _RECO
Hold and immediately proceed to step S ₁₄ . The engine operating condition at Step S ₃ is not in the roughness control region NO
In case of, the roughness correction coefficient C _{RO is changed} to C _{RO in} step S _13.
= 0 is set and the process proceeds to step S ₁₄ .

Subsequently, after calculating based on the final injection pulse width T _I formula _{T I = {T P × C} K × (1 + C RO + C A + C EN)} in step S _14, ON the idle switch in step S ₁₅ the / OFF state is determined whether deceleration operation in which the throttle valve 10 is fully closed, this in step S ₁₉ in the case of deceleration not during operation nO calculated in step S ₁₄ the final injection pulse width T _I Accordingly, the fuel injection valve 11 is operated and controlled, and the process is ended.

On the other hand, when the throttle valve 10 YES during deceleration operation of fully closed in step S _15, further steps S ₁₆ and S
As shown in FIG. 5, the engine speed Ne at S ₁₇ is the fuel cut speed N _CUT during deceleration operation and the fuel injection return speed N _REC.
Compared with each other, if it is in the fuel cut region of N _E ≧ N _CUT , it ends immediately without fuel injection, while if it is N _REC ≦ N _E ≦ N _CUT between both rotation speeds, further determines whether or not the fuel cut in step S _18, when the YES in the fuel cut is terminated without performing the fuel injection, when the NO doing the fuel injection final injection pulse proceeds to step S ₁₉ The fuel injection is performed in the width T _I , and the process ends. Further, the engine speed Ne at step S ₁₇ is YES in less than the return rotation speed N _REC ends by performing fuel injection in the final injection pulse width T _I proceeds to step S _19.

Therefore, in the operation flow of FIG. 4 above, step S ₄
~ S ₆ constitutes a combustion instability detection means 50 for detecting the combustion instability of the engine 1 by comparing the fluctuation range ΔN _E of the engine speed with the reference value N ₁ in magnitude. , If the combustion instability (rotational fluctuation range ΔN _E ) exceeds the predetermined value (reference value N ₁ ) in steps S ₇ , S ₈ , and S ₁₄ , the roughness correction coefficient C _RO is increased to increase the fuel injection valve 11 The control means 51 is configured to correct the fuel injection valve 11 so that the combustion instability becomes equal to or less than a predetermined value by increasing the final injection pulse width T _I. Further, in step S ₁₅ to S _19, at the time of the throttle valve 10 fully closed deceleration transient, a fuel correction unit 52 so as to return the fuel supply performing fuel corrected by returning less than the rotational speed N _REC after fuel cut is doing. Further, in step S ₉ to S _12, the roughness correction coefficient C value of _RO, i.e. in accordance with the correction amount by the unstable combustion of the fuel injection valve 11 return rotation speed at the time of engine deceleration transient of the fuel correction means 52 N _The correction condition changing means 53 is configured to change the _REC value (fuel correction condition).

Therefore, in the above embodiment, when the combustion fluctuation in which the rotation fluctuation width ΔN _E exceeds the reference value N ₁ is unstable, the roughness correction coefficient C _RO is largely corrected by the control means 51 and the fuel injection valve 1
Since the final injection pulse width T _I of 1 increases, the combustion state of the engine 1 becomes good, the instability of combustion is always kept below a predetermined value, and engine vibration is effectively reduced.

Then, during the engine deceleration transition in which the throttle valve 10 is fully closed, the fuel supply from the fuel injection valve 11 is cut, and then the engine speed drops to the fuel return speed N _REC. It returns and shifts to the idle operation state. In this case, the return speed N _REC (fuel correction condition) of the fuel is corrected by the correction condition changing means 53, and the engine 1
Since the roughness correction coefficient C _RO is large and exceeds the predetermined value C ₂ when the combustion state of the engine is unstable, the return rotational speed N _REC is corrected to be increased, and as a result, the fuel supply is started earlier by that amount. This effectively prevents the engine stall. Therefore, the drivability can be improved.

In the above embodiment, the fuel correction condition is the return speed N _REC of the fuel during the deceleration transient, but of course, it may be the amount of increase in the fuel during the acceleration transient.

(Effects of the Invention) As described above, according to the fuel supply control device for an engine of the present invention, in the engine in which the combustion state is controlled according to the combustion instability of the engine to reduce vibration, during transient operation Since the fuel correction condition of was changed according to the amount of correction of the combustion state due to the above combustion instability and the fuel correction during transient operation was made to correspond favorably to the original combustion state of the engine, for example during acceleration It is possible to effectively prevent rattling and engine stall during deceleration operation that cuts fuel.
The drivability can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 5 show an embodiment of the present invention, FIG. 2 is an overall configuration diagram, FIG. 3 is a block diagram showing an internal configuration of the controller, and FIG. 4 is a flow chart diagram showing the operation of the controller. FIG. 5 is an explanatory diagram showing multi-row control from fuel cut to fuel return during deceleration transition. 1 ... Engine, 11 ... Fuel injection valve, 20 ... Distributor, 21 ... Controller, 50 ... Combustion instability detection means, 51 ... Control means, 52 ... Fuel correction means, 53 ...
Correction condition changing means.

Claims (1)

[Claims] 1. A combustion instability detection means for detecting the combustion instability of the engine, a combustion adjustment means for adjusting the combustion state of the engine, and a combustion instability detected by the combustion instability detection means. A control means for controlling the combustion adjusting means so that is less than or equal to a predetermined value, and in a engine configured to reduce vibration, a fuel correcting means for performing fuel correction on the engine during transient of the engine, Fuel supply control of an engine, comprising: a correction condition changing means for changing a condition of fuel correction of the fuel correction means at the time of engine transition according to a correction amount of the combustion instability of the combustion adjusting means. apparatus.