Mechanical Reduction Gearing With Eccentric Cam Torque Transfer
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Solution Overview
Problem
Existing mechanical reduction gearing systems face challenges in achieving a high reduction ratio in a small footprint while efficiently transmitting output torque and maintaining low production costs, particularly in applications like motor vehicle wiper systems where a small diameter is required.
Innovation Solution
A mechanical reduction gearing system comprising a sun gear, planet carrier with planet shafts, cams, planet gears, and a peripheral ring gear with involute teeth, featuring two toothed wheels with eccentric cam portions and a specific tooth count configuration to achieve a high reduction ratio and efficient torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a trochoidal mechanical reduction gearing is used to obtain a high reduction ratio in a small space, then the footprint is reduced, but the production cost increases and output torque transmission becomes difficult
Solution Approach 1:
The cam component serves multiple functions: it acts as both a trochoidal reduction element and a torque transmission element. The cam profile is designed with a first portion for trochoidal reduction and a second portion for direct torque transmission, eliminating the need for separate components and simplifying manufacturing.
Solution Approach 2:
The toothed wheel acts as an intermediary between the cam and the peripheral ring gear. It receives rotational motion from the cam's second portion and transmits it through meshing with the peripheral ring gear, enabling efficient torque transmission while maintaining the compact trochoidal reduction mechanism.
2Area of stationary object
If a trochoidal mechanical reduction gearing is used to obtain a high reduction ratio in a small space, then the footprint is reduced, but the output torque transmission becomes difficult
Solution Approach 1:
The toothed wheel acts as an intermediary between the cam and the peripheral ring gear. It receives rotational motion from the cam's second portion and transmits it through meshing with the peripheral ring gear, enabling efficient torque transmission while maintaining the compact trochoidal reduction mechanism.
Solution Approach 2:
The cam is designed with portions extending in different axial directions (first and second axial portions) relative to the planet shaft. This three-dimensional configuration allows the cam to perform both reduction and torque transmission functions simultaneously, overcoming the limitation of planar trochoidal mechanisms.
3Area of stationary object
If a trochoidal mechanical reduction gearing is used to obtain a high reduction ratio in a small space, then the footprint is reduced, but the device complexity increases
Solution Approach 1:
The invention merges the trochoidal reduction function and the torque transmission function into a single cam component. The cam's first axial portion handles reduction while the second axial portion handles torque transmission, reducing the number of separate components and simplifying the overall device structure.
Solution Approach 2:
The cam component serves multiple functions: it acts as both a trochoidal reduction element and a torque transmission element. The cam profile is designed with a first portion for trochoidal reduction and a second portion for direct torque transmission, eliminating the need for separate components and simplifying manufacturing.
4Ease of manufacture
If standard involute teeth are used in the peripheral ring gear and toothed wheel, then the production cost is reduced and manufacturing is simplified, but the reduction ratio precision may be affected
Solution Approach 1:
The invention specifies that the difference in the number of teeth between the peripheral ring gear and the toothed wheel is at least three teeth. This parameter change ensures proper meshing and torque transmission while allowing the use of standard involute teeth, balancing manufacturing simplicity with functional precision.
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 system enables efficient torque transmission and reduced production costs by using standard involute teeth, allowing for a high reduction ratio in a compact design suitable for small footprints, such as in motor vehicle wiper systems.
Implementation Method 1
at least one cam positioned around the planet shaft and comprising a first axial portion concentric with the planet shaft and at least a second axial portion that is eccentric
Implementation Method 2
at least one toothed wheel suitable for meshing with the internal teeth of the peripheral ring gear and comprising at least one through-orifice offset relative to the center of the toothed wheel and configured to interact with the second axial portion of the cam so that the rotation of the cam causes the toothed wheel to mesh positively with, and therefore roll against, the peripheral ring gear
Implementation Method 3
in which the teeth of the peripheral ring gear and of the at least one toothed wheel are involute teeth as known in the field of gears
Implementation Method 4
at least one planet gear rotatably coupled to the cam on its concentric first axial portion and configured to mesh with the sun gear
Data Source
AI summary
The present invention relates to a mechanical reduction gearing (1) comprising: —an input shaft (3), —a sun gear (5) coupled in rotation to the input shaft (3), —a planet carrier (7) rotatable with respect to the input shaft (3) and supporting an output shaft (74) coaxial with the input shaft (3), said planet carrier (7) comprising at least one planet shaft (s1, s2, s3) extending parallel to the input shaft (3), —at least one cam (13) arranged around the planet shaft (s1, s2, s3) and comprising a first axial portion (p1) concentric to the planet shaft (s1, s2, s3) and at least one second eccentric axial portion (p2, p3), said at least one planet shaft (s1, s2, s3) being mounted rotatably with respect to the planet carrier (7) and/or said at least one cam (13) being mounted rotatably with respect to the associated planet shaft, —at least one planet gear (15) coupled in rotation to the cam (13) at its first concentric axial portion (p1) and configured to engage with the sun gear (5), —a peripheral annulus (17) arranged concentrically to the input shaft (3) and comprising an inner toothing, —at least one toothed wheel (r1, r2) intended to engage with the inner toothing of the peripheral annulus (17) and comprising at least one through-orifice offset with respect to the centre of the toothed wheel (r1, r2) and configured to cooperate with the second axial portion (p2, p3) of the cam (13) such that the rotation of the cam (13) causes the toothed wheel (r1, r2) to roll against the peripheral annulus (17), said rolling movement of the toothed wheel (r1, r2) being accompanied by the rotation of the planet carrier (7) with respect to the input shaft (3), and wherein the toothings of the peripheral annulus (17) and of the at least one toothed wheel (r1, r2) are toothings in the form of an involute to a circle.