Gearbox Assembly with Reversed Freewheels for Compact Speed Switching
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Solution Overview
Problem
Existing gear arrangements for hand tools face issues with high wear due to mechanical shifting elements, require additional safeguards, and are not compact enough for handheld applications, limiting their ability to operate a single unit with different speeds and requiring significant installation space.
Innovation Solution
A gear arrangement utilizing a planetary gear with two freewheels, where the blocking directions of the freewheels are inversely related to the driving shaft's rotation, allowing for switching between direct drive and transmission modes by reversing the direction of rotation, eliminating the need for additional mechanical switching mechanisms and enabling compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical shifting elements are used to provide switchable gears, then transmission ratio can be changed, but mechanical wear increases and reliability decreases
Solution Approach 1:
The patent replaces mechanical shifting elements with a magnetic field-based switching mechanism. A magnetic field is used to actuate a shifting member that engages or disengages transmission elements, eliminating direct mechanical contact for gear switching. This substitution reduces mechanical wear while maintaining the ability to provide switchable gears with different transmission ratios.
2Adaptability or versatility
If mechanical shifting elements are used, then gear switching is possible, but device complexity increases due to additional safeguards
Solution Approach 1:
The magnetic field-based switching mechanism eliminates the need for complex mechanical safeguards. The magnetic actuation provides inherent control and positioning of the shifting member, removing the need for additional mechanical guards, limit switches, or protective mechanisms that would be required with traditional mechanical shifting systems.
3Reliability
If traditional gear arrangements are used, then transmission functionality is provided, but installation space requirement increases
Solution Approach 1:
The patent employs a compact planetary gear arrangement where planet gears are nested around a sun gear, and the entire planetary assembly is contained within a ring gear. This nested configuration allows multiple transmission elements to occupy a small radial space. The magnetic shifting mechanism further compactes the design by eliminating the need for large mechanical shifting linkages and safeguards, reducing the overall installation footprint while maintaining full transmission functionality.
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 reduces mechanical wear, simplifies operation, enhances safety, and provides a compact, ergonomic design capable of operating a single unit with multiple speeds without additional mechanical components, thus addressing the limitations of prior art.
Implementation Method 1
a planetary gear (16) having a ring gear (38), a sun gear (26) and a planet gear carrier (22) on which a number of planet gears (28) are arranged, which mesh with the sun gear and the ring gear
Implementation Method 2
two freewheels (32, 46), the blocking directions of which are inversely related to one another with respect to the directions of rotation of the driving shaft (12)
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
The assembly (10) has a step-up gear (16) for transmitting input speed of a driving shaft (12) into output speed of a driven shaft (14). A sleeve-shaped freewheel (32) is arranged between the driving and driven shafts. Another sleeve-shaped freewheel (46) is arranged between a housing (48) within which the assembly is partially received and a component of the step-up gear. Locking directions of the freewheels are reversed with respect to rotation directions of the driving shaft. The freewheels switch between two or multiple transmission stages by reversal of the rotation directions. The step-up gear is formed as a spur gear.