Dual-arm tensioner with stop for hybrid drive stability
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Solution Overview
Problem
Hybrid vehicles experience increased stresses on front engine accessory drive components, leading to reduced operating life due to varying power transfer demands, which existing tensioner systems fail to adequately address.
Innovation Solution
A tensioner system with first and second tensioner arms and pulleys, biased in free arm directions, and a second tensioner arm stop to limit movement, ensuring engagement with the endless drive member across selected operating conditions, incorporating damping structures and a C-shaped base for improved stability and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-armed tensioner is used in a hybrid vehicle accessory drive, then the device complexity is low, but the reliability and operating life of belt components are reduced due to higher and varying stresses
Solution Approach 1:
The tensioner is divided into two separate arms (first tensioner arm and second tensioner arm) that can move independently. Each arm has its own pulley (first tensioner pulley and second tensioner pulley) that engages with different spans of the endless drive member. This segmentation allows each arm to independently respond to tension variations in its respective belt span, providing better stress distribution and improved reliability without excessive complexity.
Solution Approach 2:
Both tensioner arms are designed to be movable rather than fixed, allowing dynamic adjustment to varying belt tensions. The first tensioner arm is biased in a first direction and the second tensioner arm is biased in a second direction, enabling each arm to dynamically respond to changing operating conditions in hybrid vehicles, thereby improving reliability under varying power transfer demands.
2Reliability
If the second tensioner arm stop is positioned to engage throughout a selected range of operating conditions, then the stability and reliability are improved, but the device complexity increases
Solution Approach 1:
The second tensioner arm stop is pre-positioned to define a specific range of motion for the second tensioner arm. This preliminary positioning ensures that during selected ranges of operating conditions, the second tensioner arm remains engaged with the stop, maintaining stable tension without requiring complex active control systems. The stop is designed in advance to handle anticipated operating variations.
3Duration of action of moving object
If damping structures are added to reduce wear and stabilize the tensioner, then the operating life is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
Damping structures are incorporated into the tensioner design to cushion and absorb shocks and vibrations before they can cause damage to belt components and tensioner parts. This beforehand cushioning reduces wear and extends operating life by protecting components from high-stress events during hybrid vehicle operation, while maintaining relatively simple manufacturing through integrated damping elements.
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 tensioner system enhances the operating life of front engine accessory drive components by stabilizing the second tensioner arm against a stop, reducing spikes in belt tension, and minimizing wear on damping structures, while maintaining stability during torsional vibrations.
Implementation Method 1
a tensioner biasing member positioned to apply a tensioner biasing force to the first and second tensioner arms to minimize movement of the first and second tensioner arms in respective first and second directions opposite the first and second free arm directions throughout a selected range of operating conditions
Implementation Method 2
a damping structure positioned to dampen movement of the second tensioner arm
Data Source
Figure 1
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AI summary
In an aspect, a tensioner is provided for tensioning a belt and includes first and second tensioner arms having first and second pulleys respectively. The first and second pulleys are configured for engagement with first and second belt spans, and are biased in first and second free arm directions respectively. A second tensioner arm stop is positioned to limit the movement of the second tensioner arm in a direction opposite the second free arm direction. The second tensioner arm stop is positioned such that, in use, the second pulley is engaged with the endless drive member while the second tensioner arm is engaged with the second tensioner arm stop throughout a first selected range of operating conditions.