Knock detecting method

A method for detecting knocking in an internal combustion engine having a plurality of cylinders, said method comprising the steps of:

• generating a knocking signal related to the level of vibration during a predetermined period around the top dead center of each of said cylinders;
• generating an individual-cylinder frequency signal for each of said cylinders, each said individual-cylinder frequency signal being related to the number of times said knocking signals for a corresponding one of said cylinders exceed a predetermined threshold;
• generating an all-cylinder frequency signal related to the number of times all of said knocking signals exceed a second predetermined value;
• and
• determining that knocking exists when at least one of said all-cylinder frequency signal and said individual-cylinder frequency signal of at least one of said cylinders is greater than third and fourth predetermined values, respectively, and thereby generating an output.

A device for detecting knocking in an internal combustion engine having a plurality of cylinders comprising:

• means for detecting vibrations produced by a combustion engine in each of the cylinders of said engine to generate an analog vibration output corresponding to said vibration;
• means for sampling and holding a peak value of said analog vibration output generated during a predetermined period around the top dead center of each said cylinders;
• means for converting said peak value into a digital quantity;
• means for storing said digital quantity output a predetermined number of times for each of said cylinders, producing an average value of said output data stored for each of said cylinders, determining a proportion of those of said stored output data of each said cylinder which are greater than said average value by predetermined times to obtain an individual-cylinder frequency rate, and producing an average value of said individual-cylinder frequency rates by the number of said cylinders to obtain an all-cylinder frequency rate;
• and
• means for determining that there exists knocking when said individual-cylinder frequency rate of at least one of said cylinders is greater than a first predetermined value or when said all-cylinder frequency rate is greater than a second predetermined value and thereby generating an output.

A device for detecting knocking in an internal combustion engine having a plurality of cylinders, said device comprising:

• means for generating a knocking signal related to the level of vibrations during a predetermined period around the top dead center of each said cylinder;
• means for generating an individual-cylinder frequency signal for each of said cylinders, each said individual-cylinder frequency signal being related to the number of times said knocking signals for a corresponding one of said cylinders exceeds a first predetermined value, and generating an all-cylinder frequency signal related to the number of times all of said knocking signals exceed a second predetermined value;
• and
• means for determining that knocking exists when at least one of said all cylinder frequency signal and said individual-cylinder frequency signals of at least one of said cylinders is greater than third and fourth predetermined values, respectively, and thereby generating an output.