Two-Armed Tensioner with Stop Surface for Hybrid Drive
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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 configurations, which existing technologies have not adequately addressed.
Innovation Solution
An endless drive arrangement with a tensioner system featuring pivotable arms, pulleys, and a biasing member that applies preload torque to maintain engagement with a stop surface under specific operating conditions, managing belt tension and reducing component wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional single-armed tensioner is used in a hybrid vehicle, then the device complexity is low, but the operating life of drive components is reduced due to higher stresses from varying power transfer configurations
Solution Approach 1:
The tensioner is divided into two separate arms (first tensioner arm and second tensioner arm), each independently pivotable about its own pivot axis. Each arm has its own pulley that can engage with different spans of the endless drive member, allowing the system to segment the stress management function across multiple independent components rather than relying on a single complex mechanism.
Solution Approach 2:
The invention introduces a second dimension of tensioner arm movement by adding the second tensioner arm that can pivot independently about a second arm pivot axis. This creates a two-dimensional plane of tensioner arm movements, enabling the system to manage stresses from varying power transfer configurations more effectively by distributing loads across multiple angular positions and spans.
2Loss of energy
If the second tensioner arm is allowed to move freely without a stop surface, then the ease of operation is improved, but parasitic losses increase due to excessive movement and component wear
Solution Approach 1:
The second tensioner arm stop surface is positioned to limit the movement of the second tensioner arm before excessive movement can occur. This preliminary constraint prevents the arm from traveling beyond the optimal engagement position, thereby preventing parasitic losses from excessive movement and component wear while still allowing sufficient freedom of operation for the tensioner to function effectively.
3Stability of the object's composition
If the preload torque on the second tensioner arm is increased beyond 15 Nm, then the stability of the tensioner arm engagement is improved, but the energy wastage increases due to excessive biasing force
Solution Approach 1:
The invention specifies an optimal range for preload torque (between about 1 Nm and about 15 Nm) rather than using a fixed high value. This parameter optimization ensures sufficient stability of the second tensioner arm engagement with the stop surface while minimizing energy wastage from excessive biasing force. The predetermined range balances engagement stability with energy efficiency.
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 extends the operating life of front engine accessory drive components by stabilizing tensioner arms, reducing parasitic losses, and minimizing energy wastage, while maintaining efficient power transmission.
Implementation Method 1
a tensioner biasing member that is positioned to apply a tensioner biasing force to bias the first and second tensioner arms in respective first and second free arm directions
Implementation Method 2
Under static equilibrium, the second tensioner arm has a preload torque from at least the endless drive member and the tensioner biasing member, wherein the preload torque urges the second tensioner arm into engagement with the second tensioner arm stop surface
Data Source
Figure 1
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Figure 4
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.