Belt-Driven Starter Generator Slip Detection During Engine Start
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting belt slip in belt-driven integrated starter generator systems are inadequate, particularly due to unreliable detection of belt slip during engine start-up, which leads to reduced fuel efficiency, increased wear, and noise issues.
Innovation Solution
A method that evaluates a belt slip value by determining a change in velocity over time of the starter generator within a defined time window after engine start-up, using a control unit to accumulate slip numbers and compare against a limit value, initiating countermeasures if the slip exceeds the limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If belt tension is kept low to reduce parasitic friction loss, then fuel efficiency is improved, but belt slip occurs reducing reliability
Solution Approach 1:
The patent applies an active two-stage tensioner that dynamically adjusts belt tension between low and high positions based on operating conditions. During normal operation, the tensioner maintains low belt tension to reduce parasitic friction loss and improve fuel efficiency. During engine start-up or high torque demand, the tensioner switches to high tension to prevent belt slip, thereby resolving the contradiction between energy efficiency and reliability through dynamic adaptation.
2Reliability
If belt tension is increased to prevent belt slip, then reliability is improved, but parasitic friction loss increases reducing fuel efficiency
Solution Approach 1:
The active two-stage tensioner dynamically switches between low and high tension positions based on real-time operating conditions. During normal engine operation, the tensioner remains in the low tension position to minimize parasitic friction loss and maximize fuel efficiency. Only when torque demand exceeds a certain threshold or during start-up phases does the tensioner switch to high tension to prevent belt slip, thus maintaining reliability without unnecessary energy loss.
3Reliability
If conventional starter motor is used instead of BISG, then belt slip is eliminated, but fuel efficiency and torque support are reduced
Solution Approach 1:
The patent implements a control unit that continuously monitors belt slip conditions and provides feedback to the tensioner system. When belt slip is detected or predicted based on torque demand, the control unit activates the high tension position or switches to the conventional starter motor. This feedback mechanism allows the system to maintain fuel efficiency by using the BISG under normal conditions while preventing belt slip through active control, resolving the contradiction between energy efficiency and reliability.
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
Effectively detects belt slip, preventing excessive wear and noise by reducing BISG torque or using a conventional starter motor, thereby maintaining system performance and efficiency.
Implementation Method 1
the BISG is also used during engine operation to recuperate energy and support the internal combustion engine (ICE) with the torque from the recuperated energy
Implementation Method 2
the friction between the belt and the individual belt pulleys of the FEAD is not sufficient to transfer the desired torque from one belt pulley to the other
Data Source
AI summary
A method for detecting belt slip in a starter system for starting an internal combustion engine of a motor vehicle, the starter system including a belt-driven integrated starter generator. A control unit of the motor vehicle evaluates a belt slip as detected if a determined belt slip value exceeds a limit value. The belt slip value is determined to belong to a defined time window T, which opens after a start of the internal combustion engine. This determination takes into account at least one change in velocity over time value of the starter generator within the time window T. A motor vehicle with a control unit designed to carry out the method is also included.