Negative Pressure Sensor Deviation Detection for Engine Stop-Start
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Solution Overview
Problem
Existing negative pressure abnormality detection systems for internal combustion engines cannot detect deviation abnormalities in negative pressure sensors, such as gain or offset deviations, unless the output signal falls outside a predetermined normal range, leading to potential undetected issues during automatic engine stopping and restarting.
Innovation Solution
A negative pressure abnormality detection apparatus that includes a sensor to detect negative pressure and an abnormality determination part which determines if the sensor is in an abnormal condition based on the detected pressure being out of range near atmospheric pressure to vacuum pressure, even when the engine is stopped or rotating slowly, by monitoring the number of brake operations, their duration, or total operation amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the negative pressure sensor output signal is monitored only when it falls outside a predetermined normal range, then wire disconnection and short circuit failures can be detected, but deviation abnormalities such as gain or offset deviations cannot be detected
Solution Approach 1:
The patent changes the detection parameter from binary (in-range/out-of-range) to continuous monitoring of negative pressure values. By monitoring the actual negative pressure values generated during engine operation and comparing them against expected ranges, the system can detect deviation abnormalities such as gain or offset deviations in the sensor, not just complete failures.
Solution Approach 2:
The system implements feedback by continuously monitoring the negative pressure sensor output and comparing it against expected values based on engine operating conditions. When the monitored negative pressure deviates from the expected range, the system provides feedback to the control unit, which then takes corrective action such as inhibiting automatic stopping or notifying the driver.
2Reliability
If automatic engine stopping is inhibited when sensor abnormalities are detected, then engine operation reliability is maintained, but fuel consumption increases due to unnecessary engine restarts
Solution Approach 1:
The patent applies partial action by implementing a staged response to sensor abnormalities. Instead of immediately inhibiting automatic stopping for any abnormality, the system first determines whether the abnormality is severe (affecting brake operation) or mild (affecting only negative pressure generation). Only severe abnormalities trigger engine restart inhibition, while mild abnormalities allow automatic stopping to continue, thus avoiding unnecessary fuel consumption.
Solution Approach 2:
The system changes the decision parameter from binary (abnormality detected/not detected) to a graded assessment of abnormality severity. By evaluating the type and impact of the sensor abnormality on different engine functions (brake operation vs. negative pressure generation), the system dynamically adjusts whether to inhibit automatic stopping, optimizing the balance between reliability and fuel efficiency.
3Measurement precision
If the negative pressure sensor is monitored continuously during engine operation, then deviation abnormalities can be detected, but false abnormalities may be detected due to transient pressure changes during brake operations
Solution Approach 1:
The patent applies preliminary action by anticipating transient pressure changes during brake operations and preemptively excluding these periods from abnormality detection. The system identifies when brake operations are occurring (through sensor signals or other indicators) and temporarily suspends abnormality detection during these known transient periods, preventing false positives while maintaining detection accuracy during normal operation.
Solution Approach 2:
The system implements dynamic detection by adjusting the abnormality detection criteria based on engine operating conditions. Rather than using fixed thresholds, the system adapts the detection parameters according to the current operating state, such as engine speed, load, and brake operation status, thereby distinguishing between normal transient variations and actual sensor abnormalities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for the detection of vacuum-pressure-side deviation abnormalities in negative pressure sensors, preventing unnecessary automatic engine stopping and ensuring proper engine operation by inhibiting or restarting the engine based on abnormal sensor readings, thus improving operational reliability and reducing fuel consumption.
Implementation Method 1
a negative pressure sensor (46) that outputs a signal corresponding to a negative pressure that a negative pressure generation part generates through rotation of an internal combustion engine (12)
Data Source
AI summary
A negative pressure detection part detects a negative pressure from a signal of a negative pressure sensor detecting a negative pressure generated due to rotation of an internal combustion engine. The negative pressure is used to assist a vehicle driver's braking operation. An abnormality determination part determines, during continuation of the internal combustion engine stopped state, that the negative pressure sensor is in an abnormal condition if the detected negative pressure is out of a normal range near an atmospheric pressure to a vacuum pressure side when an operation of decreasing the negative pressure is performed on a brake pedal greater than or equal to a predetermined number of times or greater than or equal to a predetermined period of time or when a total operation amount of the decreasing operation is greater than or equal to a predetermined amount.