Knock suppressing apparatus and method

Claim 2

A knock suppressing apparatus for an internal combustion engine comprising: a knock sensor for generating a knock signal indicative of engine virbrations; a variable gain amplifier connected to the knock sensor for amplifying the knock signal and generating an output signal; means for generating a vibration level signal indicative of the level of the amplifier output signal; means for generating a threshold signal indicative of the level of the vibration level signal; a comparator for comparing the vibration level signal and the threshold signal; engine control means responsive to the comparator for controlling an engine operating parameter so as to suppress knocking based on the result of comparison by the comparator; and gain control means for varying the gain of the amplifier based on the threshold signal, wherein the gain control means comprises means for changing the gain in a step-wise manner between at least two different levels, with hysteresis.

Claim 3

An apparatus as claimed in claim 1 wherein the gain control means comprises means for maintaining the threshold signal within a prescribed range.

Claim 4

An apparatus as claimed in claim 1 wherein the gain control means comprises means for decreasing the gain when the threshold signal becomes greater than or equal to an upper limit.

Claim 5

An apparatus as claimed in claim 1 wherein the gain control means comprises means for increasing the gain when the threshold signal becomes less than or equal to a lower limit.

Claim 6

An apparatus as claimed in claim 1 wherein the gain control means comprises means for controlling the ignition timing of the engine.

Claim 7

An apparatus as claimed in claim 1 wherein the means for generating a vibration level comprises a peak hold circuit connected in series with the amplifier.

Claim 8

A knock suppressing method for an internal combustion engine comprising: generating a knock signal indicative of engine vibrations; amplifying the knock signal with an amplification gain; generating a vibration level signal indicative of the level of the amplified knock signal over a first period; generating a threshold indicative of the level of the vibration level signal over a second period; comparing the vibration level signal with the threshold signal; controlling an engine operating parameter based on the result of comparison so as to suppress knocking; and controlling the amplification gain based on the level of the threshold signal, wherein controlling the gain comprises: decreasing the gain when the threshold becomes greater than or equal to an upper limit; measuring an upper rotational speed of the engine corresponding to the upper limit; determining a lower rotational speed smaller than the upper rotational speed; increasing the gain when the threshold becomes less than or equal to the lower rotational speed.

Claim 9

A knock suppressing method for an internal combustion engine comprising: generating a knock signal indicative of engine vibrations; amplifying the knock signal with an amplification gain; generating a vibration level signal indicative of the level of the amplified knock signal over a first period; generating a threshold indicative of the level of the vibration level signal over a second period; comparing the vibration level signal with the threshold signal; controlling an engine operating parameter based on the result of comparison so as to suppress knocking; and controlling the amplification gain based on the level of the threshold signal, wherein controlling the gain comprises: decreasing the gain when the threshold becomes greater than or equal to an upper limit; measuring an upper rotational speed of the engine corresponding to the upper limit; determining a lower rotational speed smaller than the upper rotational speed; increasing the gain when the threshold becomes less than or equal to the lower rotational speed.

Claim 10

A method as claimed in claim 7 wherein controlling the amplification gain comprises varying the amplification gain so as to maintain the threshold signal within a prescribed range.

Claim 11

A method as claimed in claim 7 wherein controlling the gain comprises changing the gain in a step-wise manner along at least two levels.

Claim 12

A knock suppressing apparatus for an internal combustion engine comprising: a knock sensor for generating a knock signal indicative of engine vibrations; a variable gain amplifier connected to the knock sensor for amplifying the knock signal and generating an output signal; means for generating a vibration level signal indicative of the level of the amplifier output signal; means for generating a threshold signal indicative of the level of the vibration level signal; a comparator for comparing the vibration level signal and the threshold signal; engine control means responsive to the comparator for controlling an engine operating parameter so as to suppress knocking based on the result of comparison by the comparator; and gain control means for varying the gain of the amplifier based on the threshold signal, further comprising a speed sensor for sensing an engine operating condition indicative of the engine rotational speed and generating a corresponding output signal, wherein the gain control means comprises: means for decreasing the gain when the threshold signal is greater than or equal to an upper limit; means responsive to the speed sensor for determining an upper engine rotational speed corresponding to the upper limit; means for calculating a lower engine rotational speed smaller than the upper engine rotational speed; and means for increasing the gain when the engine rotational speed becomes less than or equal to the lower engine rotational speed.

Claim 13

A knock suppressing apparatus for an internal combustion engine comprising: a knock sensor for generating a knock signal indicative of engine vibrations; a variable gain amplifier connected to the knock sensor for amplifying the knock signal and generating an output signal; means for generating a vibration level signal indicative of the level of the amplifier output signal; means for generating a threshold signal indicative of the level of the vibration level signal; a comparator for comparing the vibration level signal and the threshold signal; engine control means responsive to the comparator for controlling an engine operating parameter so as to suppress knocking based on the result of comparison by the comparator; and gain control means for varying the gain of the amplifier based on the threshold signal, further comprising a speed sensor for sensing an engine operating condition indicative of the engine rotational speed and generating a corresponding output signal, wherein the gain control means comprises: means for decreasing the gain when the threshold signal is greater than or equal to an upper limit; means responsive to the speed sensor for determining an upper engine rotational speed corresponding to the upper limit; means for calculating a lower engine rotational speed smaller than the upper engine rotational speed; and means for increasing the gain when the engine rotational speed becomes less than or equal to the lower engine rotational speed.

Claim 14

A knock suppressing method for an internal combustion engine comprising: generating a knock signal indicative of engine vibrations; amplifying the knock signal with an amplification gain; generating a vibration level signal indicative of the level of the amplified knock signal over a first period; generating a threshold indicative of the level of the vibration level signal over a second period; comparing the vibration level signal with the threshold signal; controlling an engine operating parameter based on the result of comparison so as to suppress knocking; and controlling the amplification gain based on the level of the threshold signal in a step-wise manner between at least two different levels, with hysteresis.

Claim 15

A knock suppressing method for an internal combustion engine comprising: generating a knock signal indicative of engine vibrations; amplifying the knock signal with an amplification gain; generating a vibration level signal indicative of the level of the amplified knock signal over a first period; generating a threshold indicative of the level of the vibration level signal over a second period; comparing the vibration level signal with the threshold signal; controlling an engine operating parameter based on the result of comparison so as to suppress knocking; and controlling the amplification gain based on the level of the threshold signal in a step-wise manner between at least two different levels, with hysteresis.

Claim 16

A method as claimed in claim 11 wherein controlling the amplification gain comprises decreasing the gain when the threshold becomes greater than or equal to an upper limit.

Claim 17

A method as claimed in claim 11 wherein controlling the amplification gain comprises increasing the gain the threshold becomes less than or equal to a lower limit.