Negative pressure abnormality detection apparatus, and control apparatus for internal combustion engine
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.
1. A negative pressure abnormality detection apparatus, comprising:
a negative pressure sensor configured to output a signal depending on a negative pressure in a negative pressure chamber of a brake booster into which an intake negative pressure of an intake manifold generated by rotation of an internal combustion engine is introduced;
a negative pressure detection unit configured to detect the negative pressure based on the signal from the negative pressure sensor;
an abnormality determination unit configured to determine whether an abnormality occurs with the negative pressure sensor, based on whether the negative pressure detected by the negative pressure detection unit is shifted toward an atmospheric pressure side or a vacuum pressure side with respect to a threshold, when a state continues for a predetermined time or longer during which the internal combustion engine rotates and a negative pressure expending operation expending the negative pressure is not performed on a brake pedal by a driver; and
a threshold change unit configured to change the threshold depending on an opening of a throttle valve disposed in an intake pipe on an upstream side of the intake manifold, while the state continues.
2. The negative pressure abnormality detection apparatus, as claimed in claim 1 , wherein the threshold change unit sets the threshold greater when the opening is less than a predetermined threshold, while the state continues.
3. The negative pressure abnormality detection apparatus, as claimed in claim 1 , wherein the threshold change unit changes the threshold depending on a minimum value of the opening while the state continues.
4. The negative pressure abnormality detection apparatus, as claimed in claim 1 , further comprising:
a time change unit configured to change the predetermined time depending on the opening while the state continues.
5. The negative pressure abnormality detection apparatus, as claimed in claim 4 , wherein the time change unit sets the predetermined time shorted when the opening is less than a predetermined threshold, while the state continues.
6. The negative pressure abnormality detection apparatus, as claimed in claim 4 , wherein the time change unit changes the predetermined time depending on a minimum value of the opening while the state continues.
7. A control apparatus for an internal combustion engine, comprising:
an automatic control unit configured to have the internal combustion engine stop automatically when a predetermined stopping condition is satisfied, and to have the internal combustion engine restart automatically when a predetermined restarting condition is satisfied; and
an automatic stopping inhibition unit configured to inhibit the internal combustion engine from stopping automatically by the automatic control unit when the negative pressure sensor is determined to be in an abnormal state by the abnormality determination unit included in the negative pressure abnormality detection apparatus as claimed in claim 1 .