CN112112736A - Control method for reducing super detonation frequency - Google Patents

Abstract

The invention discloses a control method for reducing super detonation frequency, which comprises the following steps: 1) judging whether the working condition of the engine is in a super detonation high-frequency area, if so, turning to the step 2); 2) the throttle is controlled to decrease at a set rate until engine operating conditions are in a safe region. The method of the invention can effectively reduce the occurrence of super knock by detecting the working condition of the engine to avoid the super knock high-frequency area, does not generate additional part cost, and can be realized by software.

Description

A control method for reducing superknocking frequency

technical field

The invention relates to automobile control technology, in particular to a control method for reducing the frequency of super knocking.

Background technique

With the gradual tightening of fuel consumption and emission regulations, small-displacement supercharged direct injection engines have been developed and applied by major automobile companies due to their low fuel consumption and strong power. The extremely harmful abnormal combustion phenomenon - super knock, when super knock occurs, the maximum explosion pressure of the engine is much higher than the normal combustion pressure, and a large pressure oscillation occurs, which is very easy to damage the engine.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a control method for reducing the frequency of super knock in view of the defects in the prior art.

The technical scheme adopted by the present invention to solve the technical problem is: a control method for reducing the frequency of super knocking, comprising the following steps:

1) Determine whether the engine operating condition is in the super-knock high-frequency region, if so, go to step 2);

2) Control the throttle to decrease at a set rate until the engine operating conditions are in a safe area.

According to the above scheme, the super knock high frequency region in the step 1) is determined according to the super knock high frequency region that contains most of the super knock operating points and has the smallest range.

According to the above scheme, in the step 1), it is determined whether the engine operating condition is in the high-frequency region of super knocking, and the details are as follows:

1.1) Determine whether the engine speed is in a set interval, and the set interval is the speed range corresponding to the boundary of the high-frequency region of super knock;

1.2) Determine whether the engine load exceeds the set load threshold;

If the above conditions are met at the same time, it is judged that the engine operating condition is in the high frequency region of super knock.

According to the above solution, the load threshold value in step 1.2) is a characteristic curve input with the engine speed, and different engine speeds correspond to different thresholds.

According to the above scheme, the engine load in the step 1.2) is determined according to the engine air charge coefficient when the engine is running.

According to the above scheme, the interval of the engine speed setting in the step 1.1) is 1500 to 3000 rpm.

According to the above scheme, the load threshold in step 1.2) is greater than 1.3.

According to the above solution, in the step 2), according to the engine load, it is judged whether the engine operating condition is in a safe area.

According to the above solution, the engine load threshold for judging whether the engine operating condition is in the safe area in the step 2) is obtained by taking the safety margin for the threshold in the step 1.2).

According to the above solution, the engine load threshold for judging whether the engine operating condition is in the safe area in the step 2) is 0.9 times the threshold value in the step 1.2).

The beneficial effects that the present invention produces are:

The invention can effectively reduce the occurrence of super knock by detecting the engine operating conditions to avoid the high frequency region of super knock, and can be realized by software without generating additional cost of parts.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

Fig. 1 is the method flow chart of the embodiment of the present invention;

2 is a schematic diagram of a high-frequency region of super knocking according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a super knock threshold value according to an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

The occurrence of super knock has obvious characteristics, and it is more likely to occur in the low-speed high-load region, which is called the super-knock high-frequency region. The invention controls the opening degree of the throttle valve so that the engine operating condition does not enter the high frequency region of super knock, so as to achieve the purpose of reducing the frequency of super knock.

As shown in Figure 1, a control method for reducing the frequency of super knocking includes the following steps:

1) Determine whether the engine operating condition is in the super-knock high-frequency region, if so, go to step 2);

The super-knock high-frequency region is determined according to the super-knock high-frequency region that contains most of the super-knock operating points and has the smallest range;

Determine whether the engine operating conditions are close to the high-frequency region of super knock, as follows:

1.1) Determine whether the engine speed is in a set interval, and the set interval is the speed range corresponding to the boundary of the high-frequency region of super knock;

1.2) Determine whether the engine load exceeds the set load threshold;

If the above conditions are met at the same time, it is judged whether the engine operating condition is close to the high frequency region of super knock;

When the engine is running normally, it is judged whether the engine speed is greater than the threshold value A and less than the threshold value B, that is, it is judged whether the engine speed is in a specific range; at the same time, it is judged whether the engine load exceeds the threshold value C, and through this step, it is judged whether the engine operating condition is Near the superknocking high frequency region. The load threshold C is a characteristic curve with the engine speed as the input, and different engine speeds correspond to different thresholds.

For the determination of the boundary of the high-frequency region, that is, the acquisition of the A, B, and C thresholds, a statistical method can be used to sweep the points of the engine under all operating conditions. , the frequency of superknocking at all engine operating points. According to the statistical results of the test, the high-frequency region of super knock can be obtained. The speed range is usually 1500 to 3000 rpm, and the load is usually above 1.3 depending on the speed. The value of the threshold A/B/C is determined according to the boundary of the high-frequency region, and the boundary of the high-frequency region should contain most of the super-knock operating points while the range is the smallest. Among them, the threshold value C is the curve of the corresponding relationship between the rotational speed and the load established according to the characteristic point of the boundary load, as shown in FIG. 3 .

2) Control the throttle to decrease at a set rate until the engine operating conditions are in a safe area.

After judging that the engine operating conditions are close to the super-knock high-frequency region (that is, at or entering the boundary of the super-knock high-frequency region), the engine enters a specific mode, and the system controls the throttle to decrease at a set rate.

When the engine is running, the engine charging coefficient is expressed as the ratio of the fresh gas mass entering the cylinder to the fresh gas mass filling the cylinder under standard atmospheric pressure, which represents the current working load of the engine.

As the throttle valve opening decreases, the air entering the engine cylinder decreases, and the engine load decreases accordingly. The system judges whether the engine load is less than the threshold D, and judges whether the engine operating conditions are far away from the super knock high frequency region. The load threshold D is a characteristic curve with engine speed as input, and different engine speeds correspond to different thresholds. Threshold D is obtained by retaining a certain safety margin on the basis of threshold C, such as multiplying C by 0.9. Figure 2.

The present invention can effectively reduce the occurrence of super knock by avoiding the high frequency region of super knock, without generating extra cost of parts and components, and can be realized by software. The present invention reduces the power and torque of the engine under characteristic operating conditions while reducing the frequency of super-knock, and loses a certain amount of engine power. a solution.

It should be understood that, for those skilled in the art, improvements or changes can be made according to the above description, and all these improvements and changes should fall within the protection scope of the appended claims of the present invention.

Claims (10)

1. a control method for reducing super knock frequency, is characterized in that, comprises the following steps: 1) Determine whether the engine operating condition is in the super-knock high-frequency region, if so, go to step 2); 2) Control the throttle to decrease at a set rate until the engine operating conditions are in a safe area. 2. The control method for reducing the frequency of super knocking according to claim 1, wherein in the step 1), the high frequency region of super knocking is based on the super knocking that contains most of the super knocking operating points and the smallest range at the same time. The high frequency region of the earthquake is determined. 3. The control method for reducing super-knock frequency according to claim 1 and 2, characterized in that, in the step 1), it is determined whether the engine operating condition is in the super-knock high-frequency region, specifically as follows: 1.1) Determine whether the engine speed is in a set interval, and the set interval is the speed range corresponding to the boundary of the high-frequency region of super knock; 1.2) Determine whether the engine load exceeds the set load threshold; If the above conditions are met at the same time, it is judged that the engine operating condition is in the high frequency region of super knock. 4 . The control method for reducing the frequency of super knocking according to claim 3 , wherein the load threshold value in step 1.2) is a characteristic curve input with engine speed, and different engine speeds correspond to different thresholds. 5 . 5 . The control method for reducing the frequency of super knocking according to claim 3 , wherein the engine load in step 1.2) is determined according to the engine air charge coefficient when the engine is running. 6 . 6 . The control method for reducing the frequency of super knocking according to claim 3 , wherein the engine speed setting interval in the step 1.1) is 1500 to 3000 rpm. 7 . 7 . The control method for reducing the frequency of super knocking according to claim 3 , wherein the load threshold value in the step 1.2) is greater than 1.3. 8 . 8 . The control method for reducing the frequency of super knocking according to claim 1 , wherein, in the step 2), it is determined whether the engine operating condition is in a safe area according to the engine load. 9 . 9. The control method for reducing the frequency of super knocking according to claim 3, wherein the engine load threshold for judging whether the engine operating condition is in a safe area in the step 2) is determined by taking a safe threshold for the threshold in step 1.2). The remainder is obtained. 10. The control method for reducing the frequency of super knocking according to claim 3, wherein the engine load threshold for judging whether the engine operating condition is in a safe area in the step 2) is 0.9 times the threshold value in the step 1.2). .

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