Switchable Belt Tensioning for Starter-Generator Drives
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Solution Overview
Problem
Existing belt tensioning devices for internal combustion engines with starter generators require increased belt force to prevent slippage, leading to higher fuel consumption due to increased contact pressure.
Innovation Solution
A belt tensioning device with adjustable spring arms and an actuating element, such as electromechanical or hydraulic, that enhances spring force during starting or full-load operations, allowing for reduced contact pressure during normal operation by activating additional spring arms to support or release tension, thereby optimizing fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If increased belt force is applied to prevent slippage during starting or full-load operation, then reliability of belt drive is improved, but fuel consumption increases due to higher contact pressure
Solution Approach 1:
The belt tensioning device transitions from a static spring-based tensioning system to a dynamic system that can adjust belt force in real-time. The actuating element responds to operational conditions (starting, full-load) by activating additional spring arms only when high belt force is needed, making the tensioning system adaptive rather than continuously high-force
Solution Approach 2:
The system applies high belt force periodically or intermittently only during specific operational phases (starting or full-load operation) rather than continuously. The actuating element activates additional spring arms temporarily during these high-demand periods, then releases them during normal operation to reduce contact pressure and fuel consumption
2Force
If additional spring arms are activated to increase spring force, then belt tensioning capability is improved, but device complexity increases
Solution Approach 1:
The actuating element integrates multiple functions into a single component: it detects operational conditions, controls the engagement of additional spring arms, and adjusts belt tension accordingly. This merging reduces the need for separate control systems while achieving the desired force enhancement
Solution Approach 2:
The belt tensioning device monitors its own operational state and automatically activates or deactivates additional spring arms as needed. The actuating element responds to load conditions without external intervention, making the system self-regulating and reducing the need for complex external control mechanisms
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
The solution allows for increased spring force when needed, reducing fuel consumption by minimizing contact pressure during normal engine operation, while maintaining effective belt tensioning.
Implementation Method 1
the spring arms (4, 5) being supported by spring forces of first and second further spring arms (11, 12), which can be adjusted by an adjusting element (13) in such a way that their spring forces either support the spring forces of the spring arms (4, 5) on the endless belt or not
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a belt-tensioning device for a belt drive of an internal combustion engine, comprising an electric machine having a drive belt pulley, which can be driven by a drive shaft about a drive axis, and having at least one further drive belt pulley, wherein an endless belt wraps around the drive belt pulley and the further drive belt pulley, wherein the belt-tensioning device has a housing in which a first and a second spring arm are mounted so as to be pivotable about a common pivot axis, in each of which spring arms a tension roller having axes of rotation which are parallel to the drive axis is rotatably mounted, wherein the spring arms are supported against one another and press the endless belt together via the tension rollers in the region of the drive belt pulley, wherein a first and a second further spring arm are provided adjacent to the spring arms which are adjustable by an adjustment element in such a way that the spring forces of said further spring arms either do or do not support the spring forces of the spring arms acting on the endless belt. The design of the belt-tensioning device according to the invention permits switching of the belt tension according to operating mode when a crankshaft starter-generator is used.