Sprocketed Drive Assembly Tooth Angle Design
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Solution Overview
Problem
Track-type machines with rotatable bushings are prone to slippage and 'jumping' under heavy loading conditions due to reduced friction, leading to premature wear and control issues, and increasing the size of components to enhance friction increases manufacturing and material costs, as well as weight.
Innovation Solution
A sprocketed drive assembly with teeth having a tooth angle less than 17 degrees, featuring opposing tooth flanks with a substantially flat portion at the top and a curved portion at the base, forming a concave channel to receive a cylindrical pin member, which reduces the likelihood of bushing slippage without increasing component size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width and size of drive sprocket and drive lugs are increased to increase surface area of interaction, then friction force increases and deformation is reduced, but manufacturing and material costs increase and weight increases
Solution Approach 1:
The patent changes the geometric parameters of the tooth flanks by introducing a specific angle (between 10-20 degrees) and a curved profile with defined radius of curvature. This parameter optimization allows the tooth flanks to better conform to the bushing surface, increasing the effective contact area and friction force without increasing the overall size of the drive sprocket, thereby resolving the contradiction between reliability and weight
Solution Approach 2:
The patent applies curvature to the tooth flank surfaces by defining them with a specific radius of curvature. This curved geometry allows for better surface contact with the bushing, increasing the interaction surface area and friction force. The curved profile enables the teeth to wrap around the bushing more effectively, improving grip and resistance to slippage without requiring larger component dimensions
2Duration of action of stationary object
If rotatable bushings are used to decrease friction at the bushing-sprocket interface, then wear from friction is reduced, but slippage and jumping increase under heavy loading
Solution Approach 1:
The patent optimizes the geometric parameters of the tooth flanks, specifically the angle (10-20 degrees) and radius of curvature, to create a profile that better engages with the rotatable bushing. This parameter optimization increases the contact surface area and friction force between the teeth and bushing, providing sufficient grip to prevent slippage and jumping under heavy loading while still allowing the bushing to rotate and reduce wear
Solution Approach 2:
The curved profile of the tooth flanks with defined radius of curvature enables better conformal contact with the cylindrical bushing surface. This curvature allows the teeth to wrap around the rotating bushing more effectively, maintaining engagement and preventing slippage while accommodating the rotational movement of the bushing, thus preserving tracking stability
3Reliability
If component size is increased to increase friction force, then slippage is reduced, but power to weight ratio decreases
Solution Approach 1:
The patent optimizes the tooth flank angle and curvature parameters to maximize the effective contact area and friction force within the existing component size constraints. By carefully selecting the angle (10-20 degrees) and radius of curvature, the design achieves sufficient grip to prevent jumping and slippage without increasing the overall size of the drive sprocket, thereby maintaining the power to weight ratio
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 optimized tooth angle design enhances resistance to slippage and 'jumping' while maintaining a lightweight and efficient drive system, supporting larger loads without the need for increased component size, thus preserving the power-to-weight ratio.
Implementation Method 1
a substantially curved portion located at or near a base of the tooth flank... opposing tooth flanks of successive pairs of teeth form a substantially concave channel... adapted to receive therein a cylindrical pin member
Implementation Method 2
each tooth flank comprising a substantially flat portion located at or near a top portion of the tooth and a substantially curved portion located at or near a base of the tooth flank
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A sprocket assembly (130) for a track-type machine (100) comprises a plurality of teeth (131), radially-disposed about a center of the sprocket assembly, each of the plurality of teeth comprising opposing tooth flanks (131a), wherein successive pairs of teeth defines a substantially concave channel (134) for receiving therein a cylindrical pin member (113) associated with a track link member ( 112) of a continuous track chain (111), each tooth flank having a tooth angle less than about 17 degrees.