Two-Stage Rack-and-Pinion Gear for High-Thrust Compact Window Drives
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Solution Overview
Problem
Existing multi-stage rack and pinion gear systems for window drives are bulky and visually unappealing due to the large number of gear stages required to achieve high thrust forces, which complicates the operation and aesthetics of window systems.
Innovation Solution
A two-stage rack and pinion gear system is proposed, featuring a worm gear stage as the first gear stage and a spur gear stage with a gear having a single tooth (Z=1) as the driving member, which engages directly with the rack, allowing for high gear ratios and compact dimensions by reducing the number of gear stages and enabling self-locking for secure operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If multiple gear stages (5-8 stages) are used to achieve high thrust forces, then the required thrust force is met, but the overall dimensions and visual appearance are negatively impacted
Solution Approach 1:
The patent combines multiple gear stages into a single integrated stage by using a multi-tooth pinion that simultaneously engages with multiple spur gears. This merging approach achieves the equivalent of 5-8 gear stages in one compact unit, delivering high thrust force while maintaining small overall dimensions and avoiding visual obtrusiveness.
Solution Approach 2:
The invention transitions from a sequential multi-stage arrangement (one gear after another along a linear path) to a parallel multi-tooth engagement system where a single pinion engages multiple gears simultaneously. This dimensional reorganization compresses the gear train volume while preserving the cumulative gear ratio and thrust force multiplication.
2Speed
If multiple gear stages are used to achieve high gear ratio, then the required speed reduction is achieved, but the number of bearing points and device complexity increase
Solution Approach 1:
The patent merges multiple sequential gear stages into a single integrated gear stage where a multi-tooth pinion simultaneously engages with multiple spur gears. This consolidation achieves the equivalent speed reduction of 5-8 stages while reducing device complexity and the number of bearing points to just one rotating bearing at the pinion center.
3Speed
If a single-tooth gear (Z=1) is used in the final stage, then high gear ratio is achieved with compact dimensions, but the torque transmission requirement becomes more demanding
Solution Approach 1:
The patent segments the torque transmission function across multiple parallel gear engagements. The multi-tooth pinion simultaneously transmits torque to multiple spur gears, distributing the load and reducing the mechanical stress on each individual tooth. This segmentation allows the final single-tooth gear stage to achieve high gear ratio while maintaining adequate torque transmission capability through the combined strength of multiple engagement points.
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 configuration achieves high gear ratios, reduces the overall size of the gearbox, allows for more compact motor design, and provides self-locking to prevent reverse rotation, enhancing operational reliability and reducing noise, while maintaining high thrust force transmission capabilities.
Implementation Method 1
The first gear stage (5) is a worm gear stage, wherein the worm (6) is non-rotatably connected to the drive shaft (3)
Implementation Method 2
a gear (1) with the number of teeth Z=1, which engages directly with the teeth of the rack (2) at the gear output
Data Source
Figure 1a~1c
Figure 2
Figure 3
AI summary
The invention relates to a multi-stage rack-and-pinion gear which converts a rotary movement of a driveshaft at a gear input into a linear movement of a rack at a gear output. In order to create a multi-stage rack-and-pinion gear of this kind, in particular for use in window drives, which can transmit high shear forces at a high ratio with more compact dimensions (as compared to the prior art), a rack-and-pinion gear having at most four gear stages is proposed, wherein the last gear stage comprising the rack has, as a drive wheel, a gearwheel with a number of teeth Z=1, and the transmission ratio of each gear stage for which the driving and driven gear members are designed as wheels is determined in such a way that the rotational speed of the driven wheel is slower than the rotational speed of the driving wheel.