Accessory Drive Tensioner With Adjustable Pulley for Belt Tolerance
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Solution Overview
Problem
Conventional accessory drives for internal combustion engines with reversible electric machines face issues due to production and assembly tolerances, leading to variable belt tension, which results in higher-than-necessary tension levels, energy losses, and oversized components.
Innovation Solution
The implementation of an adjustable tensioner system with a pulley mounted on a sleeve telescopically coupled to an intermediate bushing, allowing for adjustment of the center distance between pulleys to maintain optimal belt tension, compensating for manufacturing tolerances and reducing tensioner size and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the design value of nominal tension is oversized to ensure minimum tension threshold is maintained under worst-case tolerances, then belt tension reliability is improved, but energy consumption increases and component size increases
Solution Approach 1:
The tensioner incorporates an adjustable mechanism that allows the center distance between pulleys to be modified. This dynamic adjustment capability enables the system to adapt to different belt lengths and tolerance variations, maintaining optimal tension without requiring oversized design margins, thereby reducing energy consumption while preserving reliability
Solution Approach 2:
The invention allows changing the geometric parameters of the drive system by adjusting the center distance between pulleys. This parameter modification enables optimization of belt tension under actual operating conditions rather than relying on conservative oversized design values, reducing both energy consumption and component dimensions
2Reliability
If the design value of nominal tension is oversized to ensure minimum tension threshold is maintained under worst-case tolerances, then belt tension reliability is improved, but component size increases
Solution Approach 1:
The adjustable center distance mechanism allows the tensioner to adapt its geometry to match actual belt dimensions and tolerance variations. This dynamic capability eliminates the need for oversized stationary components, reducing tensioner size and weight while maintaining reliable belt tension through adjustment rather than overdesign
Solution Approach 2:
By enabling modification of the center distance parameter, the system can be optimized for actual operating conditions rather than worst-case scenarios. This reduces the required size of the tensioner and other components while maintaining reliability through parameter optimization
3Device complexity
If production and assembly tolerances are not compensated, then device complexity is reduced, but belt tension variability increases leading to energy losses
Solution Approach 1:
The adjustable center distance mechanism provides a relatively simple dynamic adjustment capability that compensates for tolerance variations. This low-complexity adjustment system enables optimization of belt tension, reducing energy losses without requiring complex control systems or multiple components
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
This solution ensures optimal belt tension is maintained across the lifespan of the belt, reducing energy losses and component size, while maintaining reactivity to instantaneous tension variations, thus enhancing the efficiency and performance of the accessory drive.
Implementation Method 1
a spring (16) acting between the base element (11) and the intermediate element (12) so as to push the tensioner pulleys (14, 15) into contact with the belt (9)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Accessory drive for an internal combustion engine of a vehicle, comprising at least one first pulley (2) mounted on the drive shaft (3), a second pulley (5) mounted on the shaft of the electric machine (6), a belt cooperating with the pulleys (2, 5) and a tensioner comprising a first and a second tensioning pulley (14, 15) and at least one spring (16) adapted to push the tensioning pulleys into contact with respective branches (9a, 9b) of the belt; the drive further comprises an adjustable-position pulley (15, 51, 56) configured to cooperate with the endless drive element to vary the installation tension thereof.