Oil Pump Fixation Detection With Fast Pressure-Drop Diagnosis
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Solution Overview
Problem
Existing oil pump fixation detection methods, such as those disclosed in Japanese Unexamined Patent Application Publication (JP-A) No. 2017-106581, can cause discomfort to vehicle occupants due to strange sounds during diagnosis, particularly when switching to the half-discharge state, and may extend the duration of these sounds.
Innovation Solution
An oil pump fixation detecting apparatus and method that switch the oil pump's discharge state between full-discharge and partial-discharge states by setting a diagnostic target oil pressure higher than the maximum pressure in the partial-discharge state, regulating the oil pressure to match this target, and determining if the pump is fixed by observing the pressure drop after switching, thereby reducing the time in the half-discharge and high-pressure state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the oil pump is switched to the half-discharge state for fixation diagnosis, then the detection accuracy is improved, but strange sounds occur causing discomfort to occupants
Solution Approach 1:
The system performs preliminary pressure regulation to reach a diagnostic target oil pressure higher than the maximum pressure in the half-discharge state before switching. This preliminary action ensures that when the pump switches to half-discharge state, the pressure drop is maximized and the time spent in the problematic high-pressure half-discharge state is minimized, thereby reducing strange sounds while maintaining detection accuracy
Solution Approach 2:
The system rapidly switches the oil pump from full-discharge to half-discharge state after pressure regulation, minimizing the duration of the half-discharge high-pressure state that causes strange sounds. The quick transition allows accurate detection while reducing the time occupants are exposed to discomfort-causing noises
2Measurement precision
If the oil pressure is regulated to a high diagnostic target pressure, then the fixation detection accuracy is improved, but the time in high-pressure state increases causing strange sounds
Solution Approach 1:
The pressure regulator performs preliminary regulation to reach a diagnostic target oil pressure higher than the maximum pressure in the half-discharge state before the switching solenoid valve changes state. This ensures that when switching occurs, the pressure differential is maximized, enabling accurate detection while the subsequent rapid pressure drop minimizes the duration of the problematic high-pressure state
Solution Approach 2:
The system uses feedback from the pressure regulator and switching control to monitor and adjust the oil pressure dynamically. By regulating the pressure to a specific diagnostic target and then switching states, the system achieves accurate detection while the feedback mechanism ensures the high-pressure state does not persist longer than necessary, reducing strange sounds
Data Source
AI summary
An oil pump fixation detecting apparatus includes an oil pump, a discharge state switching unit, a target oil pressure setting unit, a pressure regulator, and a fixation determining unit. The discharge state switching unit performs control of switching a discharge state of the oil pump from a full-discharge state to a partial-discharge state. The fixation determining unit determines that the oil pump is not fixed in the full-discharge state in a case where oil pressure in a high-pressure oil passage has dropped by a predetermined value or more within a predetermined time, and determines that the oil pump is 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.