Evaporative Pump Barometric Pressure Inference
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Solution Overview
Problem
Existing methods for inferring barometric pressure in vehicles are unreliable, especially when dedicated sensors fail or are not present, and rely on GPS which may not be available in all areas, leading to inaccurate engine control and diagnostics.
Innovation Solution
The use of an evaporative level check module (ELCM) pump to estimate barometric pressure by drawing a vacuum across a reference orifice, correlating the pump's efficiency with barometric pressure, allowing for rationalization of other sensors and adjustment of vehicle operating parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated barometric pressure sensor is used, then barometric pressure measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The vacuum pump is designed to serve multiple functions: it evacuates the evaporative emissions system for diagnostic purposes and simultaneously infers barometric pressure through efficiency measurements. This eliminates the need for a dedicated barometric pressure sensor while maintaining measurement capability.
Solution Approach 2:
The system uses its own vacuum pump to generate the vacuum conditions needed for both evaporative system diagnostics and barometric pressure inference. The pump's performance characteristics during normal operation provide the data needed to determine barometric pressure without requiring external sensors.
2Device complexity
If barometric pressure is inferred from MAP sensor, then device complexity is reduced, but measurement precision deteriorates due to sensor failure or incorrect inference
Solution Approach 1:
The patent replaces pressure sensor-based measurement with a mechanical performance-based inference method. By measuring the vacuum pump's efficiency (power consumption vs. vacuum level), the system derives barometric pressure information from mechanical performance rather than electrical sensor signals.
Solution Approach 2:
The vacuum pump efficiency serves as an intermediary measurement that indirectly provides barometric pressure information. Instead of directly measuring pressure with a sensor, the system measures the pump's electrical power consumption and vacuum generation capability, then infers barometric pressure from this intermediate data.
3Measurement precision
If GPS is used to determine altitude changes, then barometric pressure can be inferred, but reliability decreases in remote areas without GPS reception
Solution Approach 1:
The patent extracts the barometric pressure inference capability from the vacuum pump's operational characteristics, separating it from GPS-dependent altitude measurement. This allows the system to determine barometric pressure directly through pump efficiency measurement without relying on external GPS signals or altitude data.
4Device complexity
If vacuum pump efficiency is used to infer barometric pressure, then device complexity is minimized, but measurement precision may be affected by pump performance variability
Solution Approach 1:
The system continuously monitors the vacuum pump's electrical power consumption and vacuum level, using this feedback to calculate efficiency and infer barometric pressure. The control module adjusts pump operation based on measured conditions, maintaining accurate inference despite variations in pump performance or environmental conditions.
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 method provides an accurate estimate of barometric pressure, improving engine strategies and diagnostics by rationalizing other sensors and enabling vehicle operation even without functional dedicated barometric pressure sensors, particularly in hybrid electric vehicles.
Implementation Method 1
determining an estimate of barometric pressure as a function of an efficiency of a vacuum pump configured to evacuate or pressurize the fuel system and evaporative emissions control system
Implementation Method 2
drawing a vacuum across a reference orifice of fixed diameter
Data Source
AI summary
Methods and systems are provided for determining barometric pressure. In one example, an onboard vacuum pump is utilized to draw a vacuum at a constant flow rate across a reference orifice, and the resulting vacuum level is converted to a barometric pressure. In this way, other sensors for determining barometric pressure in a vehicle may be rationalized without the use of engine operation, and in an example where the other sensors for determining barometric pressure are not functioning as desired, barometric pressure as inferred from the onboard pump may be utilized to adjust engine operation.