JPH0615839B2 - Engine controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device that adjusts and controls an air-fuel ratio in response to engine knocking.

(Prior Art) Conventionally, in engine control, for example, Japanese Patent Laid-Open No.
As shown in No. 9-200042, in the feedback zone of the air-fuel ratio, highly accurate air-fuel ratio control is performed by feedback control, open control is performed in the output zone (enrich zone), and knocking is performed in the high load state of the enrich zone. Therefore, there is a technique in which the occurrence of knocking is eliminated by retarding the ignition timing when the knocking occurs. The elimination of knocking due to the retard of the ignition timing has a problem such as a large output loss and a rise in the exhaust temperature, and since the retardation of the ignition timing alone is inefficient, knocking is delayed by the retard of the ignition timing. After elimination, the ignition timing is advanced by adjusting the air-fuel ratio to minimize output loss and obtain highly accurate engine control. That is, in the above-described prior art, when knocking occurs, first, the ignition timing is retarded to suppress the occurrence of this knocking, and thereafter, the air-fuel ratio is knocked so that the retarded ignition timing is returned to the optimum ignition timing. The ignition timing is advanced by adjusting the ignition timing so that the ignition timing is advanced, the adverse effect of the ignition timing retard is improved, and control is performed so that knocking does not occur in an optimal state.

However, in the engine control as described above, the correction of the air-fuel ratio due to the occurrence of knocking is to shift to a direction in which knocking is less likely to occur, but the correction direction is the air-fuel ratio of the supply air-fuel mixture at that time. It depends on what you are doing. That is, in the state where the excess air ratio λ = 1 and the air-fuel ratio is the stoichiometric air-fuel ratio, the ignition timing at the knock limit is in the retarded state with the smallest advance amount because the combustion speed is fast. In the region on the side, the ignition timing at the knock limit is advanced. Then, when operating in the lean region, corrective shift of the air-fuel ratio to the rich direction according to the occurrence of knocking, because the air-fuel ratio shifts to the stoichiometric air-fuel ratio direction and the combustion speed becomes faster, Knocking is likely to occur and knocking cannot be suppressed. Further, when the air-fuel ratio is in the rich region, the air-fuel ratio can be shifted to the lean side with respect to the occurrence of knocking, which makes knocking more likely, and thus the direction of correcting the air-fuel ratio must be changed according to the operating state. , Knocking may not be surely suppressed.

(Object of the Invention) In view of the above circumstances, the present invention provides a control device for an engine, in which the air-fuel ratio is corrected when knocking of the engine occurs, and the correction direction is a direction for suppressing the occurrence of knocking so as to surely suppress knocking. It is intended to provide.

(Structure of the Invention) The control device of the present invention includes knocking detection means for detecting knocking of the engine, air-fuel ratio adjusting means for receiving an output of the knocking detection means, and correcting the air-fuel ratio when knocking occurs, and When the air-fuel ratio determines whether the air-fuel ratio is in the rich region or the lean region and a signal from the air-fuel ratio determination device, the air-fuel ratio is in the rich region in the rich direction, and in the lean region when the knock occurs in the lean direction. A correction direction determining means for determining a correction direction of the air-fuel ratio by the air-fuel ratio adjusting means is provided.

FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention.

The engine 1 includes a fuel injection nozzle 3 arranged in the intake system 2.
The air-fuel ratio is controlled by adjusting the fuel injection pulse (fuel supply amount) for Further, the engine 1 is provided with a knocking detection means 4 such as a knocking sensor for detecting the occurrence of knocking from the vibration of the engine, and the knocking detection signal indicates the air-fuel ratio by controlling the fuel injection pulse output to the fuel injection nozzle 3. It is output to the air-fuel ratio adjusting means 5 for adjusting.

The air-fuel ratio adjusting means 5 corrects the fuel supply amount when knocking occurs, and corrects and shifts the air-fuel ratio supplied to the engine 1 in the direction of suppressing the occurrence of knocking.

Further, the signal of the knocking detection means 4 is output to the air-fuel ratio determination means 6, and whether the air-fuel ratio at the time of knocking occurrence is in the rich region or the lean region is determined by, for example, the fuel injection pulse from the air-fuel ratio adjusting device 5. Judgment based on
The signal of the air-fuel ratio determination means 6 is output to the correction direction determination means 7, and when the air-fuel ratio is in the rich region, the supply air-fuel ratio is corrected and transferred in the rich direction, and when it is in the lean region, the supply air-fuel ratio is changed in the transfer direction. Is determined and a signal in the transition direction is output to the air-fuel ratio adjusting means 5 to correct the air-fuel ratio in the direction in which knocking is suppressed.

That is, in the same filling state, as shown in FIG. 2, in the knock region (knock limit ignition advance), the air-fuel ratio is the most retarded (the advance amount is the smallest when the stoichiometric air-fuel ratio (air excess ratio λ = 1)). ), Knocking is likely to occur.
The rich region I on the rich side from the region near the theoretical air-fuel ratio
Then, the richer it becomes, the less knocking will occur,
On the other hand, in the lean region II on the lean side, the leaner the tendency, the less likely it is that knocking will occur, and the air-fuel ratio at the time of occurrence of knocking is determined and the air-fuel ratio is shifted to the direction in which knocking does not occur.

(Effect of the Invention) According to the present invention, when the air-fuel ratio is shifted and corrected in a direction in which knocking is less likely to occur in response to the occurrence of knocking, the correction direction changes depending on the air-fuel ratio. By determining the air-fuel ratio when knocking occurs by the fuel ratio determining means and the correction direction determining means and adjusting and controlling the air-fuel ratio in the direction of suppressing knocking, knocking can be reliably suppressed. .

(Examples) Examples of the present invention will be described below with reference to the drawings. In this embodiment, when knocking occurs, the ignition timing is first retarded to suppress knocking with good responsiveness, and then the air-fuel ratio is corrected and controlled so that knocking is less likely to occur, and the retarded ignition timing is optimally ignited. This is an example of controlling so as to proceed in time.

As shown in FIG. 3, the intake system 2 of the engine 1 is provided with an air cleaner 12, an air flow meter 13 for measuring the intake amount, and a throttle valve 14 for controlling the intake amount from the upstream side, respectively. A fuel injection nozzle 3 for each cylinder is arranged in the passage 2a.

In addition, an ignition plug 9 is provided for each cylinder in the engine body 1a, and the operating state of the engine 1 such as a knocking sensor 15 that detects the occurrence of knocking and a rotation output sensor 16 that detects the engine speed is displayed. Various sensors for detection are installed.

The fuel injection amount from the fuel injection nozzle 3 and the ignition timing by the ignition plug 9 are controlled by a control signal from a control unit 17 (microcomputer), and the control unit 17 includes the air flow meter 13, the knocking sensor 15, A detection signal from the rotation output sensor 16 or the like is input.

The control unit 17 has the functions of the air-fuel ratio adjusting means 5, the air-fuel ratio determining means 6, and the correction direction determining means 7 shown in FIG. 1, and adjusts the air-fuel ratio and the ignition timing according to the detection signals of various sensors. However, learning control is performed in the knock zone, and the ignition timing is delayed when knocking occurs, while thereafter the air-fuel ratio is adjusted and the ignition timing is advanced.

The operation of the control unit will be described with reference to the flowchart of FIG. After the start, in step S1, the engine speed Ne is determined based on the signal from the rotation output sensor 16.
And the A / D conversion signal of the intake air amount Qa is input based on the signal of the air flow meter 13 in step S2. In step S3, the basic injection amount T ₁ (injection pulse width) is calculated from the engine speed Ne and the intake air amount Qa, and similarly in step S4, the basic ignition timing θ ₁ is calculated from the engine speed Ne and the intake air amount Qa. (Advance speed) is calculated. The calculations in steps S3 and S4 may be obtained from a preset map, and various corrections such as temperature correction are also performed.

Next, in step S5, it is determined whether the operating condition is in the knock zone. This determination is based on the intake air amount Q per unit speed.
a / Ne is determined by whether or not the engine is in a high load state equal to or higher than the set value Kz, and in the low NO load range not in the knock zone, the process proceeds to steps S6 and S7 to correct the ignition timing correction value θ ₂ and the injection amount correction. After clearing the value T ₂ , the final ignition timing θ (basic ignition timing θ ₁ -correction value θ ₂ ) is calculated in step S8, while the final injection amount T (basic injection amount T ₁ + correction value T ₂ is calculated in step S9. ) Is calculated, and based on this calculation, an ignition signal is output at a predetermined ignition timing, and fuel injection is performed to perform a normal control for obtaining a predetermined amount of air-fuel ratio.

When the operating condition is high load and is in the knock zone, the determination in step S5 is YES and the process proceeds to step S10. Last time, it is determined whether or not it is the knock zone. If NO is the first knock zone, in step S11. The initial air-fuel ratio correction amount T ₀ is calculated from the table of the engine speed Ne to obtain the correction value T ₂ . This initial air-fuel ratio correction amount T ₀ is, for example, 1300 to 1500 rpm with respect to the engine speed.
The range is set to the stoichiometric air-fuel ratio range, the rotation range of 1300 rpm or less is set to the lean range, and the rotation range of 1500 rpm or more is set to the rich range.

Then, in step S12, the knock number counter Ck, the learning register R ₁ and the cumulative knock strength Rk are cleared, and the process proceeds to step S13. In addition, the step S10
When the result is YES in the knock zone last time, the process directly proceeds to step S13.

In step S13, the detection signal from the knocking sensor 15 is A / D converted and the knocking intensity Ik is input. Based on this, it is determined in step S14 whether knocking is currently occurring. If NO in which knocking has not occurred, the correction value θ ₂ is subtracted by a predetermined value dθ to advance the ignition timing θ in step S15, and then it is determined in step S20 whether learning has been completed.

Further, when knocking occurs, the determination in step S14 is YES, and in step S16, the predetermined value f · Ik is added to the correction value θ ₂ to retard the ignition timing θ. The retard angle addition value f is a constant, and the retard angle amount varies depending on the knock intensity Ik, and the retard angle amount increases when a large knock occurs. Then, in step S17, the knock number counter Ck is incremented, and in step S18, the learning register R ₁ is added to obtain the average of the ignition timings. Then, in step S19, the knock intensity Ik is added to calculate the cumulative value Rk. Then, the process proceeds to step S20.

In the state where learning is not completed in step S20, that is, NO until the knock number counter Ck reaches the set value C _0.
In this case, the final ignition timing θ and the final injection amount T are calculated and output in steps S8 and S9.

On the other hand, when the learning is completed and the determination in step S20 is YES, the average ignition timing θa is calculated from the register value R ₁ and the count value C _{0 in} step S18 in step S21.
And the average knock intensity Ia are calculated in step S22, and the register values R ₁ , Rk and the count value Ck are cleared (S23). In step S24, the reference ignition timing θ ₀ is calculated from the table of the engine speed Ne. The reference ignition timing θ ₀ is set so that the advance amount increases as the engine speed increases. Next, in step S25, the air-fuel ratio correction amount ΔT is calculated from the table of the product of the deviation between the reference ignition timing θ ₀ and the average ignition timing θa and the average knock intensity Ia obtained in step S22. This air-fuel ratio correction amount ΔT is the deviation (θ ₀ −θa
= Δθ) is a positive value and a negative value is a negative value, and the magnitude | ΔT | is set to increase as the deviation | Δθ | increases.

Then, in steps S26 to S30, the supply air-fuel ratio is determined and the correction direction is determined. That is, in step S26, it is determined whether the engine speed is 1300 rpm or less, and YE
Since the current air-fuel ratio is in the lean region when the engine speed is low at 1300 rpm or less at S, the coefficient D is set to negative (-1), that is, to the lean direction at step S27, and then step S3 is performed.
Go to 1. On the other hand, when the determination in step S26 is NO and the engine speed exceeds 1300 rpm, it is further determined in step S28 whether the engine speed is less than 1500 rpm, and if this determination is YES, 1300 to 1500 rpm.
Since the engine is in the stoichiometric air-fuel ratio region during rotation, the coefficient D is set to 0 in step S29, the correction of the air-fuel ratio is prohibited, and the process proceeds to step S31. On the other hand, if the above determination is NO, 15
Since it is in the rich region at a speed of 00 rpm or more, the coefficient D is set to positive (+1), that is, the rich direction in step S30, and the process proceeds to step S31.

In step S31, the learning correction value T ₂ is corrected based on the value of the air-fuel ratio correction amount ΔT obtained in step S25. When the coefficient D is positive, the fuel injection amount is increased to correct the air-fuel ratio to the rich side, and the final ignition timing θ and the injection amount T are calculated and output in steps S8 and S9. Therefore, when the air-fuel ratio is in the rich region corresponding to the current engine speed, the air-fuel ratio is further shifted to the rich side and corrected, while when it is in the lean region, further shifted to the lean side and corrected to knock. The ignition timing is advanced with the stop of knocking.

The reference ignition timing θ ₀ obtained in step S24 may be the basic ignition timing θ ₁ obtained in step S4.

The flowchart of FIG. 5 shows a modified example, and the determination of the air-fuel ratio and the determination of the correction direction are different from the example of FIG. The processing from step S1 to step S25 is the same as in the previous example. After obtaining the air-fuel ratio correction amount ΔT in step S25, the deviation Δθ in ignition timing is obtained in step S26. And
In step S27, the current deviation Δθ and the previous deviation Δθ ′ are compared.

If YES at step S27, in which the deviation Δθ is smaller this time, the air-fuel ratio is corrected so that knocking is suppressed, that is, when the air-fuel ratio is in the rich region, in the rich region, in the lean region. since that is fixed respectively to the lean direction when in, proceed to clear the flag F in step S28 to step S35, performs the same modified learning correction value T ₂ and FIG. 4 step S31 in.

If the determination in step S27 is NO, it is determined in step S29 whether or not the flag F has been cleared. If NO in step S27, the coefficient D is set to 0 in step S30. After setting and stopping the air-fuel ratio correction, the process proceeds to step S35. On the other hand, if the determination in step S29 is YES and the flag F has been cleared, the air-fuel ratio has not been corrected in a direction that suppresses knocking. Therefore, after the flag F is set in step S31, the correction direction is changed. In order to change it, it is determined in step S32 whether or not the coefficient D is positive, and if this determination is YES and positive (+1), the coefficient D is negative (-
On the other hand, when the determination is NO and negative (-1), the coefficient D is set to positive (+1) in step S34, and then the process proceeds to step S35.

Therefore, also in this example, when the air-fuel ratio is in the rich region, while the air-fuel ratio is further corrected to shift to the rich side,
When it is in the lean area, it is moved to the lean side and corrected.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention, FIG. 2 is an explanatory diagram for explaining basic characteristics of air-fuel ratio correction, and FIG. 3 is an overall configuration diagram showing a structural example of the present invention, FIG. 4 is a flow chart for explaining an operation example of the control unit, and FIG. 5 is a flow chart for showing another example. 1 ... Engine, 2 ... Intake system 4 ... Knocking detecting means 5 ... Air-fuel ratio adjusting means, 6 ... Air-fuel ratio determining means 7 ... Correction direction determining means 15 ... Knocking sensor 17 ... Control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoji Rikitake 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (56) References JP-A-60-62644 (JP, A) 44 (JP, U)

Claims (1)

[Claims] 1. Knocking detection means for detecting engine knocking, and air-fuel ratio adjustment means for receiving the output of the knocking detection means and correcting the air-fuel ratio when knocking occurs.
When the air-fuel ratio at the time of knocking occurrence is a rich region or a lean region, the air-fuel ratio determining means and a signal of the air-fuel ratio determining means are received, and when the air-fuel ratio is in the rich region, in the rich direction,
An engine control device comprising: a correction direction determining unit that determines a correction direction of the air-fuel ratio by the air-fuel ratio adjusting unit when knocking occurs in the lean direction when in the lean region.