Title of Invention

A SPEED REDUCER

Abstract A speed reducer comprises at least a first (3), a second (4), and a third reduction stage (5), arranged in cascade, the first stage (3) comprising a pair of gears (6, 7) with perpendicular axes, the second stage (4) comprising an epicyclic reduction unit with a sun gear (10) and respective planetary gears (11) kinematically connected thereto, the third stage comprising a pair of gears (15, 16) with parallel axes, the drive-input shaft (9) of the first stage (3) and the drive-output shaft (17) of the third stage (5) constituting the drive-input and drive-output shafts of the reducer, respectively, and having respective perpendicular axes. The drive-input shaft (14) of the third stage (5) is hollow and houses coaxially the drive-input shaft (8) of the second, epicyclic reduction stage (4); the first reduction stage comprises a bevel-gear/pinion pair (6, 7), the bevel gear (6) being fixed firmly for rotation with the drive-input shaft (8)of the second stage, at the end axially remote from the position of mounting of the second reduction stage, the bevel gear (6) being supported rotatably in the reducer at a pair of support points. Bearing-type support means (18) are provided at one of the support points, the bevel gear (6) being supported at the other support point by the self-centring supporting effect produced on the sun gear (10) by the epicyclic reduction unit, the sun gear (10) being restrained coaxially on the drive-input shaft (8) of the second stage, at the end axially remote from the position of mounting of the bevel gear (6).
Full Text A SPEED REDUCER
Technical field
The present invention relates to a speed reducer and more specifically to a speed reducer
having at least a first, second and a third reduction stage arranged in a cascade.
Technological background
The invention applies particularly to the specific field of speed reducers comprising at least
three reduction stages of which the first is constituted by a pair of perpendicular gears, the second by
an epicyclic reduction unit, and the third by a pair of parallel annular gears, the whole forming a
reducer with an input and an output which are perpendicular to one another.
The term "reducer" is used in this context in its most general meaning of a transmission
member which can operate both in a multiplying condition and in a reducing condition between a
main drive-input shaft and a main drive-output shaft.
In the specific constructional implementation of reducers of the type indicated, the drive is
brought to the sun gear of the epicyclic reduction unit by means of a shaft which extends through the
hollow pinion of the final pair of annular gears. This particular configuration is not the subject of
this patent since it is already known and described in Italian patent No. 1307377.
Disclosure of the invention
The main object of the present invention is to provide a reducer with perpendicular axes
which has particularly small transverse dimensions and which at the same time involves greater
constructional simplification than known solutions.
This object is achieved by the invention by means of a speed reducer of the above-mentioned
type. Accordingly, the present invention provides a speed reducer comprising at least a first, a
second, and a third reduction stage, arranged in cascade, the first stage comprising a pair of gears
with perpendicular axes, the second stage comprising an epicyclic reduction unit with a sun gear and
respective planetary gears kinematically connected thereto, the third stage comprising a pair of gears
with parallel axes, the drive-input shaft of the first stage and the drive-output shaft of the third stage
constituting the drive-input and drive-output shafts of the reducer, respectively, and having respective
perpendicular axes, the drive-input shaft of the third stage being hollow and housing coaxially the
drive-input shaft of the second, epicyclic reduction stage, the first reduction stage comprising a
bevel-gear/pinion pair, the bevel gear being fixed for rotation with the drive-input shaft of the
second stage, at the end axially remote from the position of mounting of the second reduction stage,
the bevel gear being supported rotatably in the reducer at a pair of support points, characterized in
that bearing support is provided at one of the support points, the bevel gear being supported at the
other support point by the self-centring supporting effect produced on the sun gear by the epicyclic
reduction unit, the sun gear being restrained coaxially on the drive-input shaft of the second stage, at
the end axially remote from the position of mounting of the bevel gear.
Brief description of the accompanying drawings
The characteristics and the advantages of the invention will become clearer from the detailed
description of two preferred embodiments thereof which are described by way of non-limiting
example with reference to the accompanying drawings, in which:
- Figure 1 is a schematic view, in axial section, of a speed reducer formed in accordance with
a first embodiment of the present invention, and
- Figure 2 is a schematic view, in axial section, of a second embodiment of the reducer
according to the invention.
Preferred embodiments of the invention
With initial reference to Figure 1, a speed reducer formed in accordance with the invention
and generally indicated 1 comprises a housing 2 inside which a first, a second, and a third reduction
stage, indicated 3, 4 and 5, respectively, are housed at least partially.
The housing 2 comprises structurally independent portions 2a, 2b and 2c which can be
connected to one another releasably to define the housing 2 for containing the reduction stages.
The first reduction stage 3 comprises a pair of gears 6, 7 which have perpendicular axes
arranged on axes Y, Z, respectively, and which are advantageously produced in the form of a bevel
gear and a pinion, respectively, meshed with one another and keyed to respective shafts 8, 9.
The shaft 9 constitutes the main drive-input shaft of the reducer 1 and is supported by
bearings 9a, 9b.
The bevel gear 6 is fixed for rotation with the shaft 8 about the axis Y by
means of a firm coupling, for example, an interference coupling, at one
end 8a of the shaft 8. The shaft 8 is also arranged to be rendered perfectly
coaxial with the bevel gear 6 by suitable centring means formed in the
mutually coupled members.
The shaft 8 constitutes the drive-input shaft of the second reduction
stage 4. This stage comprises an epicyclic reducer with a sun gear 10 which
is fixed firmly to the end 8b of the shaft 8 axially remote from the end 8a, for
example, by being produced integrally therewith or by keying. The sun gear
10 is meshed with a plurality of planetary gears 11 which are mounted on a
spider 12 in conventional manner and also mesh with a ring gear 13 fixed to
the housing 2. The spider 12 in turn is coupled for rotation with a drive-input
shaft 14 of the third stage. The shaft 14 is supported in the housing 2 by
bearings 14a, 14b provided at its opposite axial ends. A pinion 15 is fixed for
rotation with the shaft 14, for example, by being produced integrally
therewith. The pinion 15 in turn meshes with an annular gear 16 keyed to a
respective shaft 17. The shaft 17 is supported for rotation in the housing 2
about its own axis of rotation X by means of respective bearings 17a, 17b. It
constitutes the main drive-output shaft of the reducer 1 and is hollow to
permit hollow-shaft coupling with the driven shafts disposed downstream of
the reduction unit, if desired.
It is pointed out that the shaft 14 is hollow axially and the drive-input
shaft 8 of the second epicyclic reduction stage is housed therein with ample
radial clearance.
According to a principal characteristic of the invention, the bevel gear 6
is supported rotatably in the housing 2 at a pair of support points at the first
of which, in the region of the end 8a of the shaft 8, a bearing 18, preferably
of the rolling type, is provided. The second support point of the gear 6,
together with the shaft 8, is formed by the self-centring supporting effect
produced on the sun gear 10 by the planetary gears 11 that are meshed with
the sun gear. By virtue of this self-centring supporting effect, which is typical
of epicyclic reduction units, the second support point in the region of the end
8b of the shaft 8 does not require the provision of any bearing-type support
means or a respective housing seat in the housing 2; this has the advantage
of a reduced transverse dimension and a considerable constructional
simplification. To ensure adequate support of the bevel gear 6, this gear 6 is
arranged to be connected rigidly to the shaft 8, for example, by the
interference fixing described above.
Figure 2 shows a second embodiment of a reducer according to the
present invention. The reducer of the second embodiment is generally
indicated 20 and details similar to those of the previous embodiment are
marked by the same reference numerals.
The reducer 20 differs from the reducer 1 of the first embodiment in
that the bevel gear 6, together with the drive-Input shaft 8 of the epicyclic
reduction stage, is further supported at a third point by a support, preferably
of the rolling type, in which a bearing 21 is provided. The bearing 21 is
arranged axially in a position between the bearing 18 and the support zone in
the region of the sun gear 10.
Moreover, the bearing 21 is interposed radially between the hollow
shaft 14 and the shaft 8 and is preferably housed in the axiai cavity defined
inside the shaft 14. This solution can advantageously be adopted when the
self-centring effect of the sun gear 10 is not of sufficient magnitude.
In this variant of the invention, the bevel gear 6 is also advantageously
arranged to be fixed for rotation with the shaft 8 about the axis Y by means
of a torsional coupling, for example, of the type with a spiined profile 22 and
in any case such as to ensure the concentricity of the coupling. This coupling
is formed in the axial portion that is disposed between the support bearings
18 and 21. The bearing 21 advantageously comprises rolling bodies of the
needle type 23 and, again in order to reduce transverse dimensions, the
needle races may be formed directly on (facing) internal and external surface
portions of the shafts 14 and 8, respectively.
The concentric arrangement of the bearings 21 and 14a is also pointed
out. In practice, the shaft 8 is supported by the stationary portion of the
housing 2 by means of the pair of concentric bearings 14a, 21, As a result,
the bevel gear 6 is also supported at: a pair of opposed points located in the
regions of the bearings 18 and 21. This supporting effect advantageously
allows the bearing 18 to be of small dimensions since it is assisted by the
bearing 21, acting as a second support. Moreover, since the bearing 21 is
housed inside the pinion 15, the transverse dimensions are significantly
reduced and considerably less than they would be if a second bearing were
provided, mounted conventionally with a suitable housing formed in the
stationary structure of the reducer housing. The advantage connected with
greater simplification of construction (and of the number of components) in
comparison with conventional configurations should also be noted.
The invention thus achieves the object proposed, affording the
advantages indicated over known solutions.
WE CLAIM:
1. A speed reducer comprising at least a first (3), a second (4), and a third (5) reduction stage,
arranged in cascade,
- the first stage (3) comprising a pair of gears (6, 7) with perpendicular axes,
- the second stage (4) comprising an epicyclic reduction unit with a sun gear (10) and
respective planetary gears (11) kinematically connected thereto,
- the third stage (5) comprising a pair of gears (15,16) with parallel axes,
the drive-input shaft (9) of the first stage (3) and the drive-output shaft (17) of the third stage (5)
constituting the drive-input and drive-output shafts of the reducer, respectively, and having respective
perpendicular axes,
the drive-input shaft (14) of the third stage (5) being hollow and housing coaxially the drive-input
shaft (8) of the second, epicyclic reduction stage (4),
the first reduction stage (3) comprising a bevel-gear/pinion pair (6, 7), the bevel gear (6) being fixed
for rotation with the drive-input shaft (8) of the second stage, at the end axially remote from the
position of mounting of the second reduction stage, the bevel gear (6) being supported rotatably in
the reducer at a pair of support points, characterized in that bearing support (18) is provided at one of
the support points, the bevel gear (6) being supported at the other support point by the self-centring
supporting effect produced on the sun gear (10) by the epicyclic reduction unit, the sun gear (10)
being restrained coaxially on the drive-input shaft (8) of the second stage, at the end axially remote
from the position of mounting of the bevel gear (6).
2. A reducer as claimed in Claim 1, in which the bevel gear (6) of the first reduction stage (3) is
fixedly connected to the drive-input shaft (8) of the second, epicyclic reduction stage (4).
3. A reducer as claimed in Claim 1, in which the bevel gear (6), together with the drive-input
shaft (8) of the second reduction stage (4), is further supported at a third support point at which
second bearing-type support means (21) are provided, interposed between the drive-input shaft (8) of
the second reduction stage (4) and the hollow drive-input shaft (14) of the third reduction stage (5).
4. A reducer as claimed in Claim 3, in which the second support means (21) are disposed axially
in a position between the first support means and the support point in the region of the sun gear (10).
5. A reducer as claimed in Claim 3 or Claim 4, in which the second bearing-type support means
(21) are housed in the axial cavity of the hollow drive-input shaft (14) of the third reduction stage (5).
6. A reducer as claimed in one or more of Claims 3 to 5, in which respective portions of the
outer surface of the drive-input shaft (8) of the second stage (4) and of the internal surface of the
hollow drive-input shaft (14) of the third reduction stage (5), which face one another, constitute
respective races for rolling bodies of the second bearing-type support means (21).
7. A reducer as claimed in Claim 6, in which the second support means (21) comprise rolling
bodies (23) of the needle type.
8. A reducer as claimed in one or more of Claims 3 to 7, in which the drive-input shaft (8) of the
second reduction stage (4) is fixed firmly for rotation with the bevel gear (6) by torsional coupling
means.
9. A reducer as claimed in Claim 8, in which the torsional coupling means comprise a coupling
with a splined profile (22).
10. A reducer as claimed in Claim 9, in which the coupling with a splined profile (22) is provided
axially in a position between the support points relating to the first (18) and second support means
A speed reducer comprises at least a first (3), a second (4), and a third reduction stage (5),
arranged in cascade, the first stage (3) comprising a pair of gears (6, 7) with perpendicular axes, the
second stage (4) comprising an epicyclic reduction unit with a sun gear (10) and respective planetary
gears (11) kinematically connected thereto, the third stage comprising a pair of gears (15, 16) with
parallel axes, the drive-input shaft (9) of the first stage (3) and the drive-output shaft (17) of the third
stage (5) constituting the drive-input and drive-output shafts of the reducer, respectively, and having
respective perpendicular axes. The drive-input shaft (14) of the third stage (5) is hollow and houses
coaxially the drive-input shaft (8) of the second, epicyclic reduction stage (4); the first reduction
stage comprises a bevel-gear/pinion pair (6, 7), the bevel gear (6) being fixed firmly for rotation with
the drive-input shaft (8)of the second stage, at the end axially remote from the position of mounting
of the second reduction stage, the bevel gear (6) being supported rotatably in the reducer at a pair of
support points. Bearing-type support means (18) are provided at one of the support points, the bevel
gear (6) being supported at the other support point by the self-centring supporting effect produced on
the sun gear (10) by the epicyclic reduction unit, the sun gear (10) being restrained coaxially on the
drive-input shaft (8) of the second stage, at the end axially remote from the position of mounting of
the bevel gear (6).

Documents:

2685-KOLNP-2005-CORRESPONDENCE 1.1.pdf

2685-KOLNP-2005-CORRESPONDENCE.pdf

2685-KOLNP-2005-FORM 27 1.1.pdf

2685-KOLNP-2005-FORM 27.pdf

2685-KOLNP-2005-FORM-27.pdf

2685-kolnp-2005-granted-abstract.pdf

2685-kolnp-2005-granted-claims.pdf

2685-kolnp-2005-granted-correspondence.pdf

2685-kolnp-2005-granted-description (complete).pdf

2685-kolnp-2005-granted-drawings.pdf

2685-kolnp-2005-granted-examination report.pdf

2685-kolnp-2005-granted-form 1.pdf

2685-kolnp-2005-granted-form 13.pdf

2685-kolnp-2005-granted-form 18.pdf

2685-kolnp-2005-granted-form 3.pdf

2685-kolnp-2005-granted-form 5.pdf

2685-kolnp-2005-granted-gpa.pdf

2685-kolnp-2005-granted-letter patent.pdf

2685-kolnp-2005-granted-reply to examination report.pdf

2685-kolnp-2005-granted-specification.pdf


Patent Number 222908
Indian Patent Application Number 2685/KOLNP/2005
PG Journal Number 35/2008
Publication Date 29-Aug-2008
Grant Date 27-Aug-2008
Date of Filing 23-Dec-2005
Name of Patentee PIV POSIPLAN S.R.L.
Applicant Address VIA DEL LAGHETTO, 431/A, I-45021, BADIA POLESINE
Inventors:
# Inventor's Name Inventor's Address
1 CASAROTTO, GIORGIO VIA COATELLE, 426/B, I-45021, BADIA POLESINE
PCT International Classification Number F16H 3/74
PCT International Application Number PCT/EP2004/006473
PCT International Filing date 2004-06-16
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 PD2003A000151 2003-07-03 Italy