JPS61283749A - Engine control device - Google Patents

Abstract

PURPOSE:To improve the stability and responsiveness of the air-fuel ratio of an engine, by providing a comparing means for comparing the ignition timing with a reference value, and a control amount determining means receiving the output of the comparing means, for changing the control amount of the air-fuel ratio controlled by an air-fuel ratio control means. CONSTITUTION:A comparing means 7 compares the ignition timing of an engine which is controlled by an ignition timing compensating means 6 and a reference value stored in a memory means 8. An air-fuel ratio regulating means 9 regulates the air-fuel ratio so that the ignition timing comes near to the reference value. A control amount determining means 10 receives the output of the comparing means 7 and increases the control amount of the air-fuel ratio such that the larger the difference from the reference value, the larger the control amount is. With this arrangement, the stability during normal operation and the responsiveness during transition may be satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine control device that adjusts and controls ignition timing and air-fuel ratio in response to engine knocking.

(Prior art) Conventionally, in engine control, for example,
As seen in No. 9-200042, highly accurate air-fuel ratio control is performed by feedback control in the air-fuel ratio feedback zone, oven control is performed in the output zone (enrich zone), and knocking is prevented in the high load state of the enrich zone. Since this occurs, there is a technique that eliminates the occurrence of knocking by retarding the ignition timing when this knocking occurs. and,
Eliminating knocking by retarding the ignition timing has problems such as a large output loss and a rise in exhaust temperature, and retarding the ignition timing alone is inefficient, so retarding the ignition timing is used to eliminate knocking. Then, by adjusting the air-fuel ratio, the ignition timing is advanced to minimize output loss and achieve highly accurate engine control. That is, in the above prior art, when knocking occurs, the ignition timing is first retarded to suppress the occurrence of knocking, and then the air-fuel ratio is adjusted so that the retarded ignition timing returns to the optimum ignition timing. This is to advance the ignition timing by adjusting it in a direction that makes it difficult to retard the ignition timing, thereby improving the adverse effects caused by the retardation of the ignition timing, and controlling the engine so that knocking does not occur under optimal conditions.

However, in the above-mentioned engine control, the amount of air-fuel ratio correction and the amount of control of the correction speed after retarding the ignition timing are such that in a steady state, if the amount or speed of air-fuel ratio correction is large, the output fluctuations will occur. In addition, since it is easy to shift to the knocking region and cause a hunting phenomenon, it is better to have a smaller air-fuel ratio correction control weight from the viewpoint of controllability in such a steady state. On the other hand, in transient conditions such as when the load suddenly increases during acceleration, it is necessary to quickly converge the air-fuel ratio to the target value.
The larger the air-fuel ratio correction control amount, the better.

In particular, as mentioned above, the optimum air-fuel ratio obtained by modifying the air-fuel ratio in accordance with the ignition timing is determined as a compromise between exhaust temperature, output, and fuel efficiency, and is determined by operating conditions such as rotation speed, load, engine temperature, and intake air temperature. It depends. For example, in a high-speed range where the exhaust gas temperature increases, the air-fuel ratio is made rich to suppress a rise in exhaust gas temperature in order to avoid heat damage, so the optimum air-fuel ratio is richer than in a low-speed range. Therefore, if the operating conditions change, the air-fuel ratio will be operated at an air-fuel ratio that deviates from the optimal value until the air-fuel ratio converges to the optimal value, resulting in problems such as decreased output, increased exhaust temperature, and worsened fuel efficiency. occurs. Particularly during acceleration, where the engine speed changes over a short period of time, the air-fuel ratio shifts to the lean side, causing heat damage due to a rise in exhaust gas temperature, which becomes a major problem.

Therefore, in order to reduce the air-fuel ratio error when operating conditions change, the air-fuel ratio correction speed can be increased as described above, but while this reduces the air-fuel ratio error when operating conditions change, , which impairs the stability of the air-fuel ratio during steady state.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention aims to improve the stability in steady state and the air-fuel ratio in transient state by adjusting the air-fuel ratio so as to advance the ignition timing after retarding the ignition timing when engine knocking occurs. The present invention relates to an engine control device that satisfies fuel ratio responsiveness.

(Structure of the Invention) The control device of the present invention includes a knocking detection means for detecting engine knocking, and receives the output of the knocking detection means, and corrects the ignition timing to the retarded side when knocking occurs, while correcting the ignition timing to the retarded side when knocking does not occur. ignition timing correction means for correcting the ignition timing to the advanced side; storage means for storing a reference value of the ignition timing set in advance; and ignition timing controlled by the ignition timing correction means and stored in the storage means. a comparison means for comparing the comparison means with the reference value; an air-fuel ratio adjustment means receiving the output of the comparison means and adjusting the air-fuel ratio so that the ignition timing approaches the reference value; This invention is characterized in that it is further provided with a control amount determining means for increasing the amount of control tIl of the air-fuel ratio by the air-fuel ratio adjusting means as the difference between the two becomes larger.

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 an intake system 2.
The air-fuel ratio is controlled by adjusting the fuel injection pulse (fuel supply amount) for the spark plug 4, and the ignition timing is controlled by adjusting the ignition signal for the spark plug 4. Further, the engine 1 is provided with knocking detection and output means 5 using a knocking sensor or the like for detecting the occurrence of knocking from engine vibrations, etc., and the knocking detection signal is outputted to an ignition timing correction means 6.

The ignition timing correction means 6 corrects the ignition signal output timing to the ignition plug 4, that is, the ignition timing, when knocking occurs, and corrects the ignition timing to advance it to the optimum ignition timing when knocking does not occur. It is. That is, as the ignition timing of the engine 1 is advanced, the output of the engine 1 becomes higher and knocking becomes more likely to occur, so the ignition timing is advanced to the limit where knocking does not occur.

The corrected ignition timing signal from the ignition timing correction means 6 is output to the comparison means 7, and this comparison means 7 is connected to the storage means 8.
A preset reference ignition timing signal inputted from the above is compared with the corrected ignition timing signal, and a deviation between the two point hole timings is determined.

The signal from the comparison means 8 is output to an air-fuel ratio adjustment means 9 that adjusts the air-fuel ratio by controlling the fuel injection pulse output to the fuel injection nozzle 3. This air-fuel ratio adjusting means 9 adjusts the air-fuel ratio so that the corrected ignition timing approaches the reference ignition timing. In other words, at the same ignition timing, in general, the richer the air-fuel ratio, the less likely knocking will occur, and conversely, the leaner the air-fuel ratio, the more likely knocking will occur. The timing is advanced to the reference ignition timing by shifting the air-fuel ratio in a direction in which knocking does not occur.

Further, the signal of the comparison means 8 is also output to the control amount determining means 10, and the control amount determining means 10 determines that the larger the deviation between the corrected ignition timing and the reference ignition timing, the more the air-fuel ratio is adjusted by the air-fuel ratio adjusting means 9. A signal is output to this air-fuel ratio adjusting means 9 so as to increase the control amount.

To explain the basic operation along FIG. 2, curve A shows the knocking zone, curve B shows the exhaust temperature limit line, and curve C shows the output curve.

When the ignition timing and air-fuel ratio are adjusted to the optimum point a, high output performance is obtained in a region where knocking does not occur. In this state, if the air-fuel ratio shifts to the lean side due to changes in operating conditions such as during acceleration and enters the knocking zone at point b, knocking will occur, but it takes time to correct the air-fuel ratio to the rich side. Therefore, the occurrence of knocking is resolved by retarding the ignition timing and shifting the operating state to the 0 point.In this state, the output performance is reduced, so the air-fuel ratio is corrected to the rich side. Accordingly, the ignition timing is corrected to the optimum point a.When correcting this air-fuel ratio, the control amount is based on the ignition timing after the 0 point retard and the reference point a. It changes according to the difference Δθ from the ignition timing to improve responsiveness and stability.

(Effects of the Invention) According to the present invention, the occurrence of knocking can be resolved with good responsiveness by retarding the ignition timing, and the air-fuel ratio is adjusted by controlling the magnitude according to the deviation of the ignition RJfJ from the reference value. By controlling the air-fuel ratio, when there is a large deviation from the optimum value of the air-fuel ratio such as during acceleration, and therefore the deviation from the reference value of ignition timing is large, the air-fuel ratio correction speed is increased to quickly adjust the air-fuel ratio to the optimum air-fuel ratio. can be converged to. On the other hand, during steady state, the deviation of the air-fuel ratio from the appropriate quantity value is small, and therefore the deviation from the reference value of the ignition timing is small, so the air-fuel ratio correction speed becomes small and stability can be improved. This makes it possible to satisfy both steady-state stability and transient response.

(Example) The present invention will be described in detail below with reference to the drawings.

As shown in FIG. 3, the intake system 2 of the engine 1 includes, from the upstream side, an air cleaner 12 and an air 70- for measuring the amount of intake air.
A meter 13 and a throttle valve 14 for controlling the amount of intake air are interposed, and a fuel injection nozzle 3 for each cylinder is arranged in the branch passage 2a on the downstream side.

In addition, the engine body 1a is provided with a spark plug 4 for each cylinder, and further includes a knocking sensor 15 for detecting the occurrence of knocking, a rotational output sensor 16 for detecting the engine speed, etc., which monitor the operating state of the engine 1. Various sensors are installed for detection.

The amount of fuel injected from the fuel injection nozzle 3 and the ignition timing by the spark plug 4 are controlled by control signals from a control unit 17 (microcomputer).
Meter 13, knocking sensor 15, rotation output sensor 1
The detection signal from 6 etc. is inputted.

The control unit has the functions of the ignition timing correction means 6, the comparison means 7, the storage means 8, the air-fuel ratio adjustment means 9, and the am limit determination means 10 shown in FIG. The system adjusts the air-fuel ratio and ignition timing, performs learning control in the knock zone, and delays the ignition timing when knocking occurs, but thereafter adjusts the air-fuel ratio and advances the ignition timing.

The operation of the control unit will be explained along the flowchart of FIG. After the start, the engine rotation speed Ne is determined based on the signal from the rotation output sensor 16 in step S1.
is calculated, and an A/D conversion signal of the intake air 11Qa is inputted based on the signal of the air 70-meter 13 in step S2. Step S3 calculates the basic injection amount TI (injection pulse width) from the engine speed Ne and intake air amount Qa, and similarly, in step S4, the basic ignition timing θ1 (advance angle) is calculated from the engine speed Ne and intake air IQa. angle). The calculations in steps 83 and 84 may be calculated from a preset map, and various corrections such as temperature correction may also be performed.

Next, in step S5, it is determined whether the operating state is in the knock zone. This judgment is based on the intake air amount Q per unit rotation speed.
The determination is made based on whether or not a/Ne is in a high load state that is equal to or higher than the set value Kz, and if it is in the low load region (No, which is not in the knock zone), the process proceeds to steps 86 and 87, where the ignition timing correction value θ2 and the injection correction value are determined. After clearing T2, the final ignition timing θ (basic ignition timing θX - correction value θ・2) is calculated in step S8, while the final injection amount T (basic injection amount T1 + correction value T2) is calculated in step S9. Based on this calculation, normal control is performed by outputting an ignition signal at a predetermined ignition timing and injecting fuel to obtain a predetermined air-fuel ratio.

When the operating state is high load and in the knock zone, the determination in step S5 becomes YES and the process proceeds to step 810, where the corresponding learning zone n is calculated from the engine speed Ne. Then, in step S11, it is determined whether or not the learning zone is the same as the previous learning zone. If YES is the same zone, the process directly proceeds to step 514, and if NO is a different zone, step S12. In step S13, the learning register R1 and knock count counter Ck are cleared, and the process proceeds to step S14, where the previous learning zone is updated in the memory.

Subsequently, in step S15, the detection signal from the knocking sensor 15 is A/D converted to determine knock intensity 1. k is input, and based on this, it is determined in step 816 whether or not knocking is currently occurring. No knocking occursN
In the case of O, in order to advance the ignition timing θ, the correction value θ2 is subtracted by a predetermined value dθ in step 817, and then it is determined in step 818 whether learning is completed. Further, when knocking occurs, the determination in step 816 is YES.
S, and in step 819, a predetermined value f·Ik is added to the correction value θ2 in order to retard the ignition timing θ. The retardation addition value f is a constant, and the amount of retardation varies depending on the knock intensity 1, and the amount of retardation increases when large knocking occurs.

Next, in step S20, the knock number counter Ck is incremented, and in step 821, the learning register R1 is added to obtain the average ignition timing, and then in step 822, the degree of knocking is determined, and the knock intensity 1k is set to the set value. Step 81 for small knocking below Io
Proceed to step 8 to determine whether learning is complete, and if the above determination is Y.
When there is a large knock in the ES, the process advances to step 823 to proceed to a routine for changing the air-fuel ratio even in a state where learning has not been completed.

In step 818, the learning is not completed, that is, the knock count counter Ck reaches the set value CO.
In this case, the process proceeds to step 839 where the learning value Tn of the current learning zone n is read and set as the injection amount correction value T2, and then the final ignition timing θ and the final injection amount lower are calculated in steps S8 and S9. Output.

On the other hand, when the learning is completed and the determination in step 818 is YES, or when large knocking is occurring, the average ignition timing θa is calculated from the register value R1 and the count value Ck in step 821 in step S23,
Clear R1 and Ck (824). In step 825, a table of engine speed N13 (for example, the fifth
The reference ignition timing θ0 is calculated from the figure), and in step 326 the deviation Δθ between the reference ignition timing θ0 and the average ignition timing θa is calculated.
Calculate. Then, in step S27, the current deviation Δθ
and the previous deviation Δθ'.

In step 327 above, the current deviation is smaller 1
Δθ1-1Δθ' If 10, the reference ignition timing θ0
Since it is approaching , the process directly advances to step 832. Also, the deviation this time is larger 1Δθl−1Δθ′
If 1>O, in order to change the correction direction, it is determined in step 829 whether the coefficient is positive or not, and if this determination is positive (+1
), the coefficient is set to negative (-1) in step S30.
On the other hand, if the determination is No, step S3
After setting the coefficient to positive (+1) with 1, step 83
Proceed to step 2. Furthermore, the deviation this time is the same as the previous time, 1Δθ1
-1Δθ' 1=0, the coefficient is set to O in step 328 to prohibit air-fuel ratio correction, and step S32
Proceed to.

In step 832, the memory of the previous deviation Δθ′ is updated,
In step 833, an air-fuel ratio correction amount ΔT is calculated from a table of deviations Δθ (for example, FIG. 6), and based on this value, one learning value is corrected in step 834. When the coefficient is positive, the fuel injection amount is increased to correct the air-fuel ratio to the rich side, and the air-fuel ratio correction ff is determined from the table above.
1lΔT1 is set to increase as the deviation 1Δθ1 increases.

Next, it is determined whether or not the modified learning value Tn exceeds the upper limit value T r + nax (534), and if it does not exceed the upper limit (No), it is left as is, and if it exceeds (YES), it is set to the upper limit value (536), l1iIb It is judged whether the corrected learning value Tn is less than the lower limit Tnmtn (837), and if the above is No, it is left as is; if it is less than YES, the lower limit Tnii is set.
Set to n (838). Thereafter, the process proceeds to step 339, where the learned value Tn is set as the injection amount correction value T2 (air-fuel ratio correction control amount), and the final ignition timing θ and injection amount T are calculated and output in steps 88 and 89. .

Note that the basic ignition timing θ1 obtained in step S4 may be used as the reference ignition timing θ0 obtained in step S25.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram to clarify the configuration of the present invention, Fig. 2 is a characteristic diagram to explain the basic operation of control, Fig. 3 is an overall configuration diagram showing a structural example of the invention, and Fig. 4 The figure is a flowchart diagram explaining the operation of the control unit in Figure 3. Figure 5 is a characteristic diagram showing an example of a table of reference ignition timing with respect to engine speed. It is a characteristic diagram which shows an example of a table. 1... Engine 2... Intake system 5... Knocking detection means 6... Ignition timing correction means 7... Comparison means 8... ...Memory means 9...
Air-fuel ratio adjusting means 10...Controlled amount determining means 15...Knocking sensor 17...Control unit Fig. 1 Fig. 2 Progress ← Three major B1v period → Retard angle Engineering 2nd floor moat 3rd floor!j
J

Claims (1)

[Claims] (1) Knocking detection means for detecting engine knocking; receiving the output of the knocking detection means; correcting the ignition timing to the retarded side when knocking occurs, and correcting the ignition timing to the advanced side when knocking does not occur; ignition timing correction means; storage means for storing a preset reference value of ignition timing; and comparison means for comparing the ignition timing controlled by the ignition timing correction means with the reference value stored in the storage means. an air-fuel ratio adjusting means that receives the output of the comparing means and adjusts the air-fuel ratio so that the ignition timing approaches the reference value; and an air-fuel ratio adjusting means that receives the output of the comparing means and adjusts the air-fuel ratio as the difference from the reference value increases. 1. An engine control device comprising: control amount determining means for increasing the control amount of the air-fuel ratio by the means.