Fixation detecting apparatus to prevent audible sound from emanating from oil pump during oil pump operation state determination

An oil pump fixation detecting apparatus for determining an operational discharge state of an oil pump by operational fixation determination of the oil pump, the oil pump fixation detection apparatus comprising:

• the oil pump configured to raise a pressure of oil sucked in through an intake port and discharge the oil through a plurality of discharge ports;
• a high-pressure oil passage;
• and
• a processor coupled to a memory storing instructions, the processor being configured to:
• switch the discharge state of the oil pump between a full-discharge state and a partial-discharge state, all ports of the plurality of discharge ports communicating with the high-pressure oil passage in the full-discharge state, one or more ports of the plurality of discharge ports communicating with the high-pressure oil passage and another one or more ports of the plurality of discharge ports communicating with the intake port of the oil pump in the partial-discharge state;
• set a diagnostic target oil pressure directed to determining whether the oil pump is fixed in one of the full-discharge state and the partial-discharge state;
• regulate an oil pressure in the high-pressure oil passage to allow the oil pressure in the high-pressure oil passage to coincide with the diagnostic target oil pressure;
• and
• carry out a fixation determination as to whether the oil pump is fixed in one of the full-discharge state and the partial-discharge state on a basis of the oil pressure regulated by the processor,
• wherein, as full-discharge switching, the processor controls the discharge state of the oil pump in the full-discharge state, when the processor carries out the fixation determination,
• as target oil pressure setting, the processor sets, as the diagnostic target oil pressure, a value higher than a maximum pressure in the partial-discharge state, when the processor carries out the fixation determination,
• as oil pressure regulation, the processor regulates the oil pressure in the high-pressure oil passage to allow the oil pressure in the high-pressure oil passage to coincide with the diagnostic target oil pressure, when the processor carries out the fixation determination,
• the processor performs control of switching the discharge state of the oil pump from the full-discharge state to the partial-discharge state, after the full-discharge switching, the target oil pressure setting, and the oil pressure regulation have been performed,
• the processor determines that the oil pump is not operationally fixed in the full-discharge state in a case where the oil pressure in the high-pressure oil passage has dropped by a predetermined value or more within a predetermined time after the control of switching the discharge state of the oil pump from the full-discharge state to the partial-discharge state has been performed, and
• the processor determines that the oil pump is operationally fixed in the full-discharge state in a case where the oil pressure in the high-pressure oil passage does not drop by the predetermined value or more within the predetermined time after the control of switching the discharge state of the oil pump from the full-discharge state to the partial-discharge state has been performed.