Note: Descriptions are shown in the official language in which they were submitted.
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Fleld of the Invention.
~, The present invention relates to a motion transmission
~ystem, and more particularly.to a planetary gear system, ln
whlch the sun.wheel ant the annulus are operatively coupled
by a planet wheel located on a cage structure whlch ha~ a
pro~ectlng arm.
Background.
The referenced technlcal llterature deæcrlbes
a planetary gear ln whlch a cage element 18 formed as a single
arm on whlch a planetary wheel 1B Journalled, ln engagement with
the sun gear and an internal gear of the annulus. Slnce the
sun gear and the annulus have gear teeth which mesh *lth the
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plahe~arygear~ lubrication at the engagement polnts of the
gear teeth is necessary. If the shafts carrying the sun gear
and the annulus are not ln precise alignment, difficulties
arise and any misalignment can only be within the range of play
between the respective gears on the planetay wheel, the sun
and the annulus.
The Invent io n .
It is an ob~ect to provide a planetary gearing which
requires little maintenance or service, little lubrication, and
which permits misalignment of the shaft carrying the
sun gear with the shaft carrying the annulus to a greater
extent than heretofore posslble, while providing for better
synchroni~ed operation of the respective gears.
Briefly, a flexible belt is coupled between the
i~ternal gearing of the annulas and the external gearing of the
sun wheel, the flexible belt being held:in engagement with the
internal gear of the sun wheel by an engagement wheel which forms
the planet wheel, carried by an arm of the cage. The belt
i~ formed as a positive drive element, for example as a toothed
or ribbed belt, to mesh with the internal gear of the annulus
and the external gear of the sun wheel, or may be formed as a
sprocket chain, with the respective gear teeth meshin8 or
engaging with the sprocket elements of the sprocket chain;
equivalent other structures may also be used.
By using a flexible coupling element to transfer
power between the sun wheel, the cage, and the annulus, the
advantages of a planetary gear system can be obtained coupled
with the aduan~ages of a flexible belt or chain drive.
These advantages, as far as the gear are concerned, are compact
construction, and a wide spectrum of transmission possibilities
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due to the varlous combinations possible in drives of the
planet gear systems; and, with respect to the flexible
transmlssion belt system, high reliability wlth low service
or maintenance requirements, essential insensitlvity to offsets
S between shafts, or non-concentric placement of bearings,
low noise, and the li~e.
Drawings:
Fig. l is a highly schematlc side view of the planet
gear system in accordance with the present invention;
Fig. 2 is a schematic side view of the system of
Fig. l, taken along the section line II-II of Fig. l;
Fig. 3 is a ~chematic side view similar to Fig. 2, and
i` illustrating a variation of the system; and
;i Fig. 4 is a schematic front view, similar to Fig. l,
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and illustrating another embodiment.
Detailed Deicription.
Referring first æO Figa. l and 2- A first main
i shaft l carries the sun gear 2, to rotate with the shaft l.
; The sun gear 2 has an external gearlng 3 thereon.
A second main shaft 4 is positioned essentially
coaxially with respect to the first main shaft l. The second
shaft 4 carries an annulus 5, for rotation therewith. The
~'r annulus 5 has an lnternal gearing 6, and a substantially larger
diameter than the ~un gear 2, being spaced therefrom by a
~ 25 dlstance 7 (Fig. l).
- In accordance with the present invention, the sun
i~ gear 2 and the annulus 5 are ~coupled by a flexible endless belt
or chain element 15. The belt element 15 which, or exam~le, -~
` is a toothed belt or gear belt, is held in engagement with
-- 30 gearing 6 of the annulus 5 by planet wheels l2, l3, l4 which,
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in turn, are located on a cage structure 8, termlnating in
three arms 9, 10, 11. The planet wheels 12, 13, 14 are
positioned essentially at the ends of the arms 9, 10, 11.
The cage structure is rotatable about the second shaft 4,
although it could be rotatable about shaft 1 as ~ell, and
~ournalled thereon.
The periphery of the respective engagement or planet
rollers 12, 1~, 14 i8 close to the inner gearing 6 of the annulus,
~ust far enough therefrom to permit passage of the flexible
endless b-elt element 15 therebetween.
The belt element 15, as shown in Fig. 1, is an
externally geared belt, although it could be replaced by a
chain, sprocket chain or the like. The belt element 15 i8
carrled between the planet wheels 12, 14 about the sun -~
; 15 wheel 2 in form of a reverse loop, such that the external
gearing on the belt 15 is in engagement wlth the teeth 3 of
the sun gear 2.
In accordance with a preferred embodiment of the
invention, a resilient or ad~ustable tensioning roller 18 i8
in engagement with the inside of the belt 15. It i8 held on an
arm 17, pro~ecting from arm 10 of the cage element, and spring-
loaded by a spring 181, shown only schematically, to
provide the appropriate operating ten6ion for the belt 15.
Spring 18' preferably is ad~ustably positioned on the arm 17 or
arm 10, respectively, as shown by double arrow 17'.
The drive in accordance with the present invention permits a
wide variety of choices between driving elements and driven
element~, in dependence upon which one of the shafts are the
driving or driven shaft and if the cage 8, 9, 10, 11 is held
in flxed position or not. The referenced literature as well
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201 ~232
as many other technological dictionaries describe the
various combinations of the chain of drive transmissions
possible in such a system. Table l on page 593 of the
referenced literature lists 12 different variations,
in dependence on which one of the gear elements, the sun gear,
the cage, or the annulus, form the driv~ing portion or the driven
portion, or are msintained in fixed position, to thereby
provide transmissions of different transmission ratios,
locked transmission, or branching of rotary power.
Fig. 3, in schematic representation, illustrates an
arrangement in which the cage elemant 8' is coupled to a third
shaft 4', which is surrounded by a hollow shaft 19, coupled to
the annulus 51. Thus, either the sun wheel 2 ', the annuluæ 5',
or the cage 8' can be used, selectively, as a drive shaft, a
driven shaft, or as a fixed element about which the sun and
annulus will rotate. Suitable coupling elements to the shafts
; l', 4', l9 are shown only echematically since they are well known.
The structure shown in Figs. l and 3 cen be used
with one, two or three engagement or planet rollers 12, 13, l4;
of course, more such rollers can be used, and the cage
structure 8 can hav~ four or more arms, each one retaining a
respective pressure roller planet wheel. This provides for
additlonal power transfer positions between the respective
`` belts l5, 15 ' (Fig. 3), the sun gear, and the annulus.Fig. 4 il~ustrates another variation of the planetary
gear in accordance with the present invention. The cage l08
includes a slngle arm 109~ at the end thereof an engagement
planet roller 1 ] 2 is rotatably secured. The sun gear 102
has an outer gearing l03, and it is surrounded by an annulus
: 30 105 with an internal gearing ]06. The planet roller 112 is
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positioned so that it i8 spaced sllghtly from the gearing
106. The arm 109 of the cage 108 additionally includes a
pro;ecting link or lever 112 which carries a roller 118, to
form a tension roller for the flexible transmission element 115.
~;~ 5 The roller 118 can be movably positioned on arm 117, for
example by a spring or by a fixed ad~ustment element, for
adjustment in accordance with the arrow 118'.
The flexible power transfer element 115 has inter- ;~
engaging coupllng elements on both sides, for example by
`~ 10 being formed as a double-sided toothed or gear belt, or a
sprocket chain. The belt 115 is in engagement ~ith its internal
gearing or ~ith the inner portion of the sprocket chain with the
outer gearing 103 of the sun wheel 102 and, with its outside,
is in engagement with the inner gearing 106 of the annulus 105,
.~ 15 engagement pressure being maintained by the engagement or planet
wheel 1 12 .
Various arrangements are possible, to vary the
use of the respective wheels as drive elements, driven elements
or fixed elements, and, likewise, to use the cage element 108
~i, 20 with the planet 112 thereon as a driving, driven, or fixed
~:' element.
The shafts ],-4 or l', 4', 19', and similar shafts
coupled to the respec~ive wheels and elements of Fig. 4, and
not shown therein for simplicity of the drawing, can be in
alignment; the flexible belt 15, 15', 115, however, permits
some misalignment of the respective ~haft~ which may be
greater than the mlsalignment possible when planet gears
-` are in engagement with the sun gear and the internal gear of
.i; the annulus. Thus, although the~shaftsshould be aligned, it is
sufficient that they are in essential alignment, the gearing
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system having the advantage of low maintenance, low noise
and compact constructlon,with the additional advantage of
requiring lesser tolerances in manufacture and tolerance
of misalignment of shafts which ought to be aligned, coupled
S with the advantages of flexibility regarding which one of the
elements of the planetary system are ~he driving, driven
or fixed portions.
: Various changes and modifications may be made, and
any features descrlbed herein may be used with any others,
within the scope of the inventive concept.
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