阅读说明：本技术 降低增压直喷汽油机早燃频次的控制方法 (Control method for reducing pre-ignition frequency of supercharged direct-injection gasoline engine ) 是由 满全平 刘庆波 李儒龙 杜佳正 肖文涛 于 2020-03-31 设计创作，主要内容包括：本发明涉及汽车控制技术领域,具体涉及一种降低增压直喷汽油机早燃频次的控制方法。若所有气缸爆震推迟点火角度平均值SA大于标定阈值SA1且持续时间Δt1超过t1,且任意一个或多个单缸的爆震推迟点火角度SR大于标定阈值SR1且持续时间Δt2超过t2,则对发动机进行限扭处理；若所有气缸爆震推迟点火角度平均值SA大于标定阈值SA3且持续时间Δt5超过t5,且任意一个或多个单缸的爆震推迟点火角度SR大于标定阈值SR3且持续时间Δt6超过t6,则对发动机进行限扭处理,且对单缸进行断油处理。根据爆震控制点火推迟角度反馈信号,降低发动机扭矩,如限扭后发动机爆震程度仍不受控制,则对爆震程度高的气缸进行断油控制。上述两个措施综合作用,可减少后续发生早燃的概率。(The invention relates to the technical field of automobile control, in particular to a control method for reducing the pre-ignition frequency of a supercharged direct injection gasoline engine. If the average SA of the knock retarded ignition angles of all the cylinders is larger than a calibrated threshold SA1 and the duration time Delta t1 exceeds t1, and the knock retarded ignition angle SR of any one or more single cylinders is larger than a calibrated threshold SR1 and the duration time Delta t2 exceeds t2, carrying out torque limiting treatment on the engine; and if the average SA of the knock retarded ignition angles of all the cylinders is greater than a calibrated threshold SA3 and the duration time delta t5 exceeds t5, and the knock retarded ignition angle SR of any one or more single cylinders is greater than a calibrated threshold SR3 and the duration time delta t6 exceeds t6, carrying out torque limiting treatment on the engine and carrying out fuel cut-off treatment on the single cylinder. And controlling an ignition delay angle feedback signal according to the knocking, reducing the torque of the engine, and if the knocking degree of the engine is not controlled after torque limitation, performing oil cut control on the cylinder with high knocking degree. The two measures are combined, so that the probability of the subsequent pre-ignition can be reduced.)

1. A control method for reducing the pre-ignition frequency of a supercharged direct injection gasoline engine is characterized by comprising the following steps: collecting detonation ignition delay angle feedback signals of all cylinders;

entering a first control mode if the average value SA of the knock retarded ignition angles of all the cylinders is greater than a calibrated threshold SA1 and the duration time Deltat 1 exceeds a certain time t1, and the knock retarded ignition angle SR of any one or more single cylinders is greater than a calibrated threshold SR1 and the duration time Deltat 2 exceeds a certain time t 2;

entering a second control mode if the average value SA of the knock retarded ignition angles of all the cylinders is greater than a calibrated threshold SA3 and the duration time Deltat 5 exceeds a certain time t5, and the knock retarded ignition angle SR of any one or more single cylinders is greater than a calibrated threshold SR3 and the duration time Deltat 6 exceeds a certain time t 6;

in the first control mode, only the engine is subjected to torque limiting treatment;

and in the second control mode, carrying out torque limiting treatment on the engine and carrying out oil cut-off treatment on the corresponding one or more single cylinders.

2. The control method for reducing the pre-ignition frequency of the supercharged direct injection gasoline engine according to claim 1, characterized in that: in the first control mode, if the average value SA of the knock retarded ignition angles of all the cylinders is smaller than a calibration threshold SA2 and the duration time Delta t3 exceeds a certain time t3, and the knock retarded ignition angles SR of all the single cylinders is smaller than a calibration threshold SR2 and the duration time Delta t4 exceeds a certain time t4, the first control mode is exited.

3. The control method for reducing the pre-ignition frequency of the supercharged direct injection gasoline engine according to claim 1, characterized in that: in the second control mode, if the average value SA of the knock retarded ignition angles of all the cylinders is smaller than a calibration threshold SA4 and the duration time Delta t7 exceeds a certain time t7, and the knock retarded ignition angles SR of all the single cylinders are smaller than a calibration threshold SR4 and the duration time Delta t8 exceeds a certain time t8, the second control mode is exited.

4. The control method for reducing the pre-ignition frequency of the supercharged direct injection gasoline engine according to claim 1, characterized in that: the calibration threshold SA3 is greater than the calibration threshold SA1, and the calibration threshold SR3 is greater than the calibration threshold SR 1.

5. The control method for reducing the pre-ignition frequency of the supercharged direct injection gasoline engine according to claim 3, characterized in that: the calibration threshold SA4 is smaller than the calibration threshold SA3 and larger than the calibration threshold SA1, and the calibration threshold SR4 is smaller than the calibration threshold SR3 and larger than the calibration threshold SR 1.

6. The control method for reducing the pre-ignition frequency of the supercharged direct injection gasoline engine according to claim 1, characterized in that: the maximum number of single cylinders for carrying out the oil-cut treatment is n2, the total number of the engine cylinders is n1, and n1-1 is not less than n 2.

Technical Field

The invention relates to the technical field of automobile control, in particular to a control method for reducing the pre-ignition frequency of a supercharged direct injection gasoline engine.

Background

With the tightening of emission and oil consumption regulations, the small-displacement pressurization direct injection technology is generally adopted in the current automobile industry, and the probability of pre-ignition is greatly increased while high energy density is realized. Once the gasoline engine has sustained pre-ignition, the damage to the engine body is extremely serious. The explosion pressure and the combustion pressure generated by pre-ignition are large, and the instantaneous heat release rate is high, so that combustion chamber components such as a spark plug, a piston, an air valve and the like are damaged, and the engine is scrapped.

Under normal conditions, the knock sensor can be used for carrying out knock detection and knock control, so that the knocking of the engine caused by normal aging, carbon deposit or low-octane fuel can be effectively controlled. However, conventional knock control functionality does not effectively protect the engine in the event of a failure of the engine internals. For example, a partially cracked spark plug ceramic body may not conduct heat from the center electrode, and even if the knock control function has moved the ignition angle back to its limit, the spark plug may still initiate pre-ignition resulting in severe engine knock. In such a case, if appropriate protective measures are not taken in time, the occurrence of pre-ignition is further aggravated, and eventually, the spark plug and even the engine body are permanently damaged.

Disclosure of Invention

The invention aims to provide a control method for reducing the pre-ignition frequency of a supercharged direct injection gasoline engine aiming at the defects of the prior art, and the control method can still effectively reduce the pre-ignition frequency under the condition of the failure of internal parts of the engine.

The technical scheme of the invention is as follows: comprises that

Collecting detonation ignition delay angle feedback signals of all cylinders;

entering a first control mode if the average value SA of the knock retarded ignition angles of all the cylinders is greater than a calibrated threshold SA1 and the duration time Deltat 1 exceeds a certain time t1, and the knock retarded ignition angle SR of any one or more single cylinders is greater than a calibrated threshold SR1 and the duration time Deltat 2 exceeds a certain time t 2;

entering a second control mode if the average value SA of the knock retarded ignition angles of all the cylinders is greater than a calibrated threshold SA3 and the duration time Deltat 5 exceeds a certain time t5, and the knock retarded ignition angle SR of any one or more single cylinders is greater than a calibrated threshold SR3 and the duration time Deltat 6 exceeds a certain time t 6;

in the first control mode, only the engine is subjected to torque limiting treatment;

and in the second control mode, carrying out torque limiting treatment on the engine and carrying out oil cut-off treatment on the corresponding one or more single cylinders.

Preferably, in the first control mode, if the average value SA of the knock retarded ignition angles of all the cylinders is smaller than a calibrated threshold SA2 and the duration Δ t3 exceeds a certain time t3, and the knock retarded ignition angles SR of all the cylinders is smaller than a calibrated threshold SR2 and the duration Δ t4 exceeds a certain time t4, the first control mode is exited.

Preferably, in the second control mode, if the average value SA of the knock retarded ignition angles of all the cylinders is smaller than the calibration threshold SA4 and the duration Δ t7 exceeds a certain time t7, and the knock retarded ignition angles SR of all the cylinders are smaller than the calibration threshold SR4 and the duration Δ t8 exceeds a certain time t8, the second control mode is exited.

Preferably, the calibration threshold SA3 is greater than the calibration threshold SA1, and the calibration threshold SR3 is greater than the calibration threshold SR 1.

Preferably, the calibration threshold SA4 is smaller than the calibration threshold SA3 and larger than the calibration threshold SA1, and the calibration threshold SR4 is smaller than the calibration threshold SR3 and larger than the calibration threshold SR 1.

Preferably, the number of single cylinders subjected to the fuel cut-off treatment is at most n2, the total number of the engine cylinders is n1, and n2 is not more than n 1-1.

The invention has the beneficial effects that: controlling the engine to reduce the engine torque in a safe mode according to the feedback signal of the ignition delay angle of the knock control, and if the knock degree of the engine is still uncontrolled after torque limitation, performing fuel cut control on the cylinder with high knock degree, thereby avoiding pre-ignition possibly caused by the fault of internal parts of the engine. The two measures are combined, so that the probability of subsequent pre-ignition can be reduced, and the engine is protected. The durability life and NVH performance of the engine can be improved, and the engine has a great advantage of reducing the failure rate of the engine in the market.

Drawings

FIG. 1 is a control logic diagram of a control method for reducing the pre-ignition frequency of a supercharged direct injection gasoline engine according to the present invention.

Detailed Description

The invention will be further described in detail with reference to the following drawings and specific examples, which are not intended to limit the invention, but are for clear understanding.

As shown in FIG. 1, a control method for reducing the pre-ignition frequency of a supercharged direct injection gasoline engine comprises the following steps:

collecting detonation ignition delay angle feedback signals of all cylinders;

entering a first control mode if the average value SA of the knock retarded ignition angles of all the cylinders is greater than a calibrated threshold SA1 and the duration time Deltat 1 exceeds a certain time t1, and the knock retarded ignition angle SR of any one or more single cylinders is greater than a calibrated threshold SR1 and the duration time Deltat 2 exceeds a certain time t 2;

entering a second control mode if the average value SA of the knock retarded ignition angles of all the cylinders is greater than a calibrated threshold SA3 and the duration time Deltat 5 exceeds a certain time t5, and the knock retarded ignition angle SR of any one or more single cylinders is greater than a calibrated threshold SR3 and the duration time Deltat 6 exceeds a certain time t 6;

in the first control mode, only the engine is subjected to torque limiting treatment;

and in the second control mode, the engine is subjected to torque limiting treatment, and one or more corresponding single cylinders are subjected to oil-cut treatment. The fuel cut-off means that ignition fuel injection control is not performed in the cylinder any more, and the possibility of abnormal combustion is eliminated from the source.

Preferably, in the first control mode, if the average value SA of the knock retarded ignition angles of all the cylinders is smaller than a calibrated threshold SA2 and the duration Δ t3 exceeds a certain time t3, and the knock retarded ignition angles SR of all the cylinders is smaller than a calibrated threshold SR2 and the duration Δ t4 exceeds a certain time t4, the first control mode is exited.

Preferably, in the second control mode, if the average value SA of the knock retarded ignition angles of the cylinders is smaller than a calibrated threshold SA4 and the duration time Delta t7 exceeds a certain time t7, and the knock retarded ignition angles SR of all the single cylinders are smaller than a calibrated threshold SR4 and the duration time Delta t8 exceeds a certain time t8, the second control mode is exited.

Preferably, the calibration threshold SA3 is greater than the calibration threshold SA1, and the calibration threshold SR3 is greater than the calibration threshold SR 1.

Preferably, the calibration threshold SA4 is smaller than the calibration threshold SA3 and larger than the calibration threshold SA1, and the calibration threshold SR4 is smaller than the calibration threshold SR3 and larger than the calibration threshold SR 1.

Preferably, the number of single cylinders subjected to the fuel cut-off treatment is at most n2, the total number of the engine cylinders is n1, and n2 is not more than n 1-1.

The ignition angle threshold, the time threshold and the torque limit value can be calibrated according to a three-dimensional table of the rotating speed and the load, in the embodiment, SA1 is 5 degrees, SR1 is 9 degrees, SA2 is 4 degrees, SR2 is 8 degrees, SA3 is 7 degrees, SR3 is 11 degrees, SA4 is 6 degrees, and SR4 is 10 degrees; t1, t2, t5 and t6 are 20ms, t3, t4, t7 and t8 are 12s, n2 is n1-1, and the torque limit value is 40%.

Details not described in this specification are within the skill of the art that are well known to those skilled in the art.