MALFUNCTION DIAGNOSIS DEVICE AND MALFUNCTION DIAGNOSIS METHOD FOR KNOCK SENSOR

摘要

To enable, with a simple control, a malfunction of a type wherein the output from a knock sensor becomes excessively large to be detected, a knock-sensor malfunction diagnosis device includes a control section configured to determine that knocking has occurred when the magnitude of a knocking vibration frequency component derived from an output signal from a knock sensor exceeds a first threshold value, and diagnose the knock sensor as malfunctioning when a prescribed diagnostic condition wherein knocking cannot occur is satisfied and the magnitude of the knocking vibration frequency component derived from the output signal from the knock sensor exceeds a second threshold value. The control section is further configured to determine that the diagnostic condition is satisfied for a time interval from a time when a predetermined time period has expired after fuel-cutoff has started to a time when the fuel-cutoff ends, during execution of the fuel-cutoff.

主权项

1. A knock-sensor malfunction diagnosis device, comprising:
a knock sensor for detecting a vibration of an internal combustion engine; a control means for determining that knocking has occurred when a magnitude of a knocking vibration frequency component derived from an output signal from the knock sensor exceeds a first threshold value, and the control means configured to: determine whether a prescribed diagnostic condition wherein knocking cannot occur is satisfied, diagnose the knock sensor as malfunctioning when the diagnostic condition is satisfied and the magnitude of the knocking vibration frequency component derived from the output signal from the knock sensor exceeds a second threshold value, and determine that the diagnostic condition is satisfied for a time interval from a point of time when a predetermined time period has expired after fuel-cutoff has started to a point of time when the fuel-cutoff ends, during execution of the fuel-cutoff.