EPS Current Sensor Delays Engine Stop During Parking
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Solution Overview
Problem
Engine controllers in vehicles often inadvertently shut off the engine during parking maneuvers, reducing drivability and increasing fuel consumption and emissions, as they rely on steering angle sensors that are costly to maintain and replace.
Innovation Solution
An engine control module with an auto-start/stop module that uses a current sensor to monitor the electric power steering system's current, delaying engine shutdown during low-speed maneuvers like parking, thereby improving drivability and reducing maintenance and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steering angle sensor is used to detect parking maneuvers, then engine auto start/stop can prevent shutdown during parking, but maintenance and replacement costs increase
Solution Approach 1:
The patent uses EPS current as an intermediary indicator to detect parking maneuvers indirectly. Instead of directly monitoring steering angle through expensive sensors, the system monitors the current drawn by the EPS system, which increases during steering operations. This intermediary measurement provides sufficient information to detect parking maneuvers while avoiding the cost and complexity of dedicated steering angle sensors.
Solution Approach 2:
The patent replaces the mechanical/electrical steering angle sensing system with an electrical current monitoring system. By substituting the steering angle sensor with a current sensor that monitors EPS system draw, the invention eliminates the need for complex mechanical steering angle detection while maintaining the ability to identify parking maneuvers through the characteristic current patterns.
2Loss of energy
If engine shuts off during parking maneuvers, then fuel consumption and emissions are reduced, but drivability deteriorates
Solution Approach 1:
The patent implements dynamic engine control that adapts to driving conditions. The auto start/stop system dynamically adjusts its behavior based on real-time detection of maneuver type (parking vs. normal stop). During detected parking maneuvers, the engine remains running to maintain drivability, while during normal stops, the engine shuts off to reduce fuel consumption. This dynamic adaptation resolves the contradiction by making the system context-aware.
Solution Approach 2:
The system uses feedback from EPS current monitoring to continuously assess whether the vehicle is undergoing a parking maneuver. This feedback loop allows the engine control module to make real-time decisions about whether to permit engine shutdown, ensuring that fuel savings are achieved only when appropriate while maintaining drivability when needed.
3Measurement precision
If steering angle sensor is integrated with EPS system, then parking maneuver detection is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the parking maneuver detection function from the steering angle sensing system and implements it separately through EPS current monitoring. By taking out the detection function and implementing it through a different mechanism (current sensing rather than angle sensing), the invention avoids the need for expensive integrated sensors while maintaining detection capability.
Solution Approach 2:
The patent makes the EPS current sensor serve multiple functions: it continues to monitor EPS system performance while also enabling parking maneuver detection. This multi-functionality eliminates the need for separate dedicated sensors, reducing manufacturing costs while maintaining measurement precision for the primary EPS function and adding the secondary parking detection capability.
Data Source
AI summary
A vehicle includes an electric power steering (EPS) system coupled to a steering wheel of a vehicle. A current sensor senses EPS current drawn by the EPS system. A engine control module controls operation of an engine of the vehicle and includes an auto start/stop module to selective y start and stop the engine independent from user input to start and stop the engine. The auto start/stop module selectively delays an auto engine stop based on the EPS current.