Negative pressure abnormality detection device and internal combustion engine control device

Abstract

A negative pressure abnormality detection apparatus includes a negative pressure sensor to output a signal representing negative pressure in a negative pressure chamber of a brake booster into which intake negative pressure of an intake manifold generated by rotation of an engine is introduced; a negative pressure detection unit to detect the negative pressure based on the signal; an abnormality determination unit to determine whether an abnormality occurs with the negative pressure sensor, based on whether the negative pressure is shifted toward atmospheric or vacuum pressure relative to a threshold, when a state continues for a predetermined time or longer during which the engine rotates and a negative-pressure-expending braking operation is not performed; and a threshold change unit to change the threshold depending on opening of a throttle valve in an intake pipe connected with the intake manifold, while the state continues.

Description

technical field [0001] The invention relates to a negative pressure abnormal detection device and a control device for an internal combustion engine. Background technique [0002] Conventionally, there is known a negative pressure abnormality detection device that determines that a negative pressure sensor is abnormal (for example, refer to Patent Document 1). Such an abnormality detection device includes a negative pressure sensor that outputs a signal corresponding to the negative pressure, and detects the negative pressure based on the signal from the negative pressure sensor. Then, based on the result of the negative pressure detection, it is determined whether or not there is an abnormality in the negative pressure sensor. Specifically, the negative pressure sensor is determined to be in an abnormal state when the signal from the negative pressure sensor has been deviated from a desired normal range for a predetermined time or longer due to disconnection, short circuit...

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Problems solved by technology

[0008] Therefore, if the negative pressure threshold value used to determine whether the above-mentioned negative pressure sensor has a deviation abnormality is fixed to a constant value independent of the throttle opening, for example, when the throttle opening is relatively large, although the negative pressure sensor does not cause atmospheric pressure The deviation of the negative pressure sensor is abnormal, but since the detected negative pressure is smaller than the fixed threshold, there is a possibility that the negative pressure sensor may be misjudged as being in an abnormal state.

And, conversely, when the throttle opening is relatively small, although the negative pressure sensor causes an abnormal deviation to the atmospheric pressure side, since the detected negative pressure is larger than the fixed threshold value, there is a possibility that the abnormality cannot be determined.

Also, when the throttle valve opening is relatively large, although the negative pressure sensor causes a deviation abnormality toward the vacuum pressure side, since the detected negative pressure is smaller than the threshold value, there is a possibility that the abnormality cannot be determined.

And, conversely, when the throttle opening is relatively small, although the negative pressure sensor does not cause a deviation abnormality to the vacuum pressure side, since the detected negative pressure is larger than the threshold value, there is a possibility that the abnormality judgment is erroneous.

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