Motorised Belt Tensioning Device with Eccentric Mounting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power tools with belt drives face issues with belt overstretching due to complex tensioning devices that require multiple steps and can lead to incorrect operation, potentially causing belt drive failure.
Innovation Solution
A simplified tensioning device that allows pulleys to transition between eccentric and concentric arrangements using a mounting element with an eccentric, eliminating the need for complex structural designs and spring-loaded tensioning, ensuring the belt is not permanently under tension and preventing overstretching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex tensioning device based on eccentric cam principle is used to maintain belt tension, then the belt can be kept under tension, but the device becomes complex and prone to incorrect operation
Solution Approach 1:
The patent removes the complex eccentric cam mechanism and spring elements from the tensioning device. Instead, it uses a simple mounting element with an eccentric that allows the pulley to be positioned eccentrically during installation, after which the pulley returns to concentric position under belt tension, maintaining reliable belt tension without complex components
Solution Approach 2:
Instead of using a mechanism that actively maintains tension through complex components, the invention inverts the approach by using the belt's own tension to return the pulley to its concentric position. The mounting element with eccentric allows temporary eccentric positioning for installation, but the belt tension itself drives the return to concentric position, eliminating the need for complex tension-maintaining mechanisms
2Reliability
If a tensioning device with multiple work steps is used to tension the belt, then the belt can be tensioned, but the operation becomes difficult and error-prone
Solution Approach 1:
The mounting element with eccentric is designed to automatically guide the pulley into the correct concentric position once the belt is installed and tension applied. The eccentric geometry pre-determines the return path, eliminating the need for multiple manual adjustment steps and reducing operational complexity while ensuring reliable belt tensioning
3Reliability
If the belt is permanently spring-loaded by a self-tensioning device, then the belt remains under tension, but progressive elongation of the elastic belt occurs
Solution Approach 1:
The patent implements periodic tensioning action rather than continuous spring loading. The mounting element with eccentric allows the pulley to be positioned eccentrically during installation, then the belt tension periodically returns the pulley to concentric position. This periodic action maintains belt tension without continuous spring force, preventing progressive elongation of the elastic belt
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 provides a straightforward and reliable belt tensioning mechanism that maintains constant pulley distance, reducing the risk of belt damage and simplifying the power tool's structural design, ensuring efficient operation without progressive elongation of the elastic belt.
Implementation Method 1
at least one of the pulleys can be brought into an arrangement eccentric to its receiving axis and that a mounting element is provided which is rotatably accommodated around the tool axis and has an eccentric, by means of which the pulley can be loosened by turning the mounting element around the tool axis
Implementation Method 2
an elastic belt is stretched between the pulleys. A tensioning device is provided and designed in such a way that the tension in the elastic strap is maintained by the elasticity of the strap itself
Data Source
Figure 1
Figure 2a~2c
Figure 3a~5
AI summary
The engine-operated device (100) has a motor (10), and a tool (12) that is driven by the motor via a belt drive unit (11). The belt drive unit is provided for rotating a drive-side pulley (14) about a drive axis (13), and tool-side pulleys (16) about a tool axis (15). A belt (17) is tensioned over the drive-side and tool-side pulleys. A mounting structure (18) is provided such that an eccentric arrangement is recyclable with respect to the pulleys driven about the drive and tool axes. An independent claim is included for method for assembling belt between engine and tool.