Driver Selectable Low Speed Mode for Stop/Start Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing stop/start systems in internal combustion engines do not allow vehicles to move at low speeds without frequent engine shutdowns, which can be inconvenient during parking maneuvers and compromise fuel economy when disabled.
Innovation Solution
A driver-selectable low speed mode that disables stop/start technology at limited speeds, allowing vehicles to move without frequent engine shutdowns while maintaining fuel efficiency during normal operation, implemented through an additional shifter detent or button, with audible and visual cues to reengage standard drive mode above a threshold speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If stop/start technology is enabled to improve fuel economy, then fuel efficiency is improved, but the vehicle cannot move smoothly at low speeds without frequent engine shutdowns
Solution Approach 1:
The system dynamically adjusts stop/start functionality based on vehicle speed. A low-speed mode is activated when vehicle speed falls below a threshold (e.g., 6 mph), disabling engine shutdowns during low-speed operation while maintaining them during normal operation. This dynamic adaptation resolves the contradiction by making the system behavior flexible rather than fixed.
Solution Approach 2:
The system changes the operational parameter of engine shutdown eligibility based on vehicle speed conditions. When speed drops below the threshold, the parameter governing engine shutdown is modified to prevent shutdowns, allowing smooth low-speed movement while preserving fuel economy benefits at higher speeds.
2Ease of operation
If stop/start technology is completely disabled to allow smooth low-speed movement, then ease of operation is improved, but fuel economy benefits are compromised
Solution Approach 1:
The driving operation is segmented into different speed zones: low-speed mode (below threshold) and normal mode (above threshold). Stop/start technology is applied selectively to each segment - disabled in low-speed segment to ensure smooth operation, and enabled in normal segment to maximize fuel economy. This segmentation allows both contradictory requirements to be satisfied in their respective operating domains.
Solution Approach 2:
The system dynamically switches between two operational states based on speed threshold crossing. When vehicle speed exceeds the threshold, stop/start functionality is re-enabled, automatically transitioning from the low-speed mode. This dynamic state change ensures fuel economy benefits are captured during normal driving without sacrificing low-speed operability.
3Ease of operation
If a driver switch is added to disable stop/start functionality, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The system provides self-service by automatically detecting low-speed conditions and activating the appropriate mode without requiring driver intervention. The engine control unit monitors vehicle speed and autonomously disables stop/start functionality when the threshold is exceeded, eliminating the need for manual switches or buttons while maintaining driver convenience.
Solution Approach 2:
The system implements feedback through speed threshold monitoring. The engine control unit continuously receives speed signals and uses this feedback to automatically adjust stop/start system operation. When speed feedback indicates low-speed operation, the system responds by disabling engine shutdowns, creating a closed-loop control that simplifies the overall system architecture.
Data Source
AI summary
A driver controllable low speed mode for a stop/start technology-equipped vehicle. The vehicle comprises an internal combustion engine with stop/start technology having an engine controller, a transmission connected to the internal combustion engine, and a shifter connected to the transmission and the engine controller. The shifter is operable to place the transmission into one of a plurality of operating modes, the operating modes including at least a low speed mode wherein stop/start technology is disabled. The engine controller is operable to detect vehicle operation above a speed or acceleration threshold and cause an audible chime or message to be played or a visual cue displayed to prompt the driver to deactivate the low speed mode. The engine controller is further operable to detect a sustained acceleration attempt when the transmission is in low speed mode and to disable low speed mode for a predetermined period of time upon this detection.