Machine element or mechanism – Gearing – Plural power paths to and/or from gearing
Patent
1979-09-04
1984-07-17
Braun, Leslie A.
Machine element or mechanism
Gearing
Plural power paths to and/or from gearing
74785, 74801, F16H 344, F16H 5710, F16H 128
Patent
active
044598769
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to gear assemblies and in particular to planetary gear systems.
2. Background Art
In the conventional planetary gear system, the planet gears are mounted to a carrier requiring the use of planet bearings.
As described by Nicholas P. Chironis in a publication entitled "Clusters of Rollers Boost Ratios in Friction Drives", a planetary roller drive is disclosed having a plurality of rows of planet rollers. In one form, the drive was arranged so that a substantial portion of the rolling surface was replaced by gear teeth with the rolling surface functioning as a bearing to keep the roller gear in its correct position in the cluster.
DISCLOSURE OF INVENTION
The present invention comprehends an improved gear assembly wherein a plurality of planet gears are arranged to float in the system eliminating the need for the planet gear carrier and bearings. The planet gears are positioned by gear mesh only in the assembly.
In the illustrated embodiment, the gear assembly includes an inner sun gear, an outer ring gear disposed coaxially of the sun gear, a plurality of planet gears having first teeth meshing with the sun gear and second teeth meshing with the ring gear, and an output ring gear meshing with the first teeth coaxially of the sun gear.
The sun gear may have axially spaced, similar sets of teeth and the planetary gears have correspondingly axially spaced sets of first teeth with the output ring gear meshing with one set only of the first teeth.
In the illustrated embodiment, the second teeth of the planet gears are disposed axially between the sets of the first teeth for engagement with the outer ring gear.
The output ring gear meshes with the planetary gear first teeth radially outwardly concentrically of the meshing of the planetary gear first teeth with the sun gear.
More specifically, the sets of planetary gear first teeth may have different axial extents.
One set of the planet gear first teeth may have an axial extent substantially equal to the axial extent of the set of second teeth.
The outer ring gear may comprise a helical gear.
Meshing teeth in the assembly may be arranged to have a partially roller contact at the pitch diameter.
A relatively large number of planet gears may be utilized, and in the illustrated embodiment, eight planet gears are utilized.
The gear assembly of the present invention is extremely simple and economical of construction while providing improved power transmission, improved load equalization, low cost manufacture, facilitated reversibility of the design, and very high reduction ratios as desired.
The gear assembly provides an increased efficiency and low maintenance.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a fragmentary diametric section of a gear assembly embodying the invention; and
FIG. 2 is a pitch diameter detail illustration of the gear assembly.
BEST MODE FOR CARRYING OUT THE INVENTION
In the exemplary embodiment of the invention as disclosed in the drawing, a gear assembly generally designated 10 is shown to include an inner sun gear generally designated 11 carried on a drive shaft 12.
As shown in FIG. 1, the sun gear may include a first set of teeth 13 and a second set of teeth 14 spaced axially from teeth 13. Teeth 14 are accurately axially aligned with teeth 13, and in the illustrated embodiment, have an axial extent approximately twice the axial extent of teeth 13.
The gear assembly further includes a plurality of planet gears each generally designated 15 having first teeth 16 and 17 which, in the illustrated embodiment, comprise axially spaced sets of teeth with a second set of teeth 18 disposed intermediate teeth set 16 and 17 and meshing with an outer ring gear 19. In the illustrated embodiment, outer ring gear 19 is fixed concentrically of shaft 12.
An output ring gear 20 meshes with planet gear teeth 17 and is mounted to an output drive shaft 21 extending coaxially of drive shaft 12.
As shown in FIG. 2, in the illustrated embodiment, eight planet gears 15 are provided equiangularly spaced abo
REFERENCES:
patent: 1633052 (1927-06-01), Watts
patent: 1799740 (1931-04-01), Felton
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patent: 3015973 (1962-01-01), Doerrtes
patent: 3240083 (1966-03-01), Stoddard
patent: 3686978 (1972-08-01), Knoblach et al.
patent: 4095323 (1978-06-01), Silvesti
patent: 4116293 (1978-09-01), Fukui
"Clusters of Rollers Boost Ratios in Friction Drives", Nicholas P. Chironis, pp. 330-332.
Eichorst, Jr. John H.
Kohler Ramon C.
Braun Leslie A.
Caterpillar Tractor Co.
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