Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TRANSMITTING UNIT
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transmitting unit, and more particularly to
a
transmitting unit using bearings and the eccentric principle to reduce or
increase the
rotational speed.
2. Description of the Prior Art
Conventionally, a transmitting unit reducing the rotational speed, which has
been
industrially used, reduces or increases the rotational speed of the input
shaft mainly by
disposing gears. The transmitting unit mainly uses worm gears or epicyclical
trains, and
examples of the transmitting unit are disclosed in Japanese Patent Laid-open
No. Sho
60-91043 and Japanese Patent Laid-open No. Sho 63-214542 for further details.
However, since the aforementioned transmitting unit uses relative movement of
meshed gears, much power is lost and much noise and vibration is generated.
Beyond
that, the transmitting unit is mainly used for heavy load. Furthermore, the
structure of
the transmitting unit is so complicated that it is hard to install the unit,
and an output
shaft is reversibly rotated when an input shaft is rotated.
In order to settle the aforementioned problems, U.S. Patent No. 4,736,654
allowed to Zhu S. Ren and entitled "transmitting unit" discloses a
transmitting unit
reducing speed that uses bearings.
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According to the transmitting unit of Ren, an eccentric sleeve and bearings
are
rotated to push transmitting rods, when an input shaft is rotated. In
addition, rolling
members that are linearly moved in a radial direction on the outer sides of
the
transmitting rods are moved along the waves of an outer race.
By the aforementioned operation, the rotational speed of an output shaft
mounted to the transmitting race is reduced, and the output shaft is rotated
in the same
rotational direction as that of the input shaft.
However, the structure of the transmitting unit has a disadvantage in that it
is
complicated and many parts are required to assemble the transmitting unit.
Furthermore, the transmitting unit cannot be easily manufactured. Namely, the
transmitting unit is rather an ideal unit.
SUMMARY OF THE INVENTION
The present invention has been made to solve the aforementioned problem, and
accordingly it is an object of the present invention to provide a transmitting
unit that has
an integrally formed transmitting race, an integrally formed outer race, and
an input
shaft in which an eccentric portion is integrally formed therewith, without
using a
separate eccentric sleeve so as to increase the strength of the unit and
minimize the
unit.
It is another object of the present invention to provide a transmitting unit
that is
precisely maintained and decreases the noise and the vibration thereof during
the
operation of the unit.
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In order to achieve the aforementioned objects of the present invention, the
present invention provides a transmitting unit comprising an input shaft
driven by a
driving device; a sleeve driven together with the input shaft when the input
shaft is
driven and having a first concentric portion, a second concentric portion, and
an
eccentric portion; a first bearing assembled along the outer periphery of the
first
concentric portion; a second bearing assembled along the outer periphery of
the
second concentric portion; a third bearing assembled along the outer periphery
of the
eccentric portion and strangely enough moving when the input shaft is driven;
an
integrally formed transmitting race having a first flange surrounding the
outer periphery
of the first bearing, a second flange surrounding the outer periphery of the
second
bearing, and a third flange surrounding the outer periphery of the third
bearing and
integrally formed with the first and second flanges, the third flange having a
plurality of
radial holes spaced apart at a predetermined distance; the same plurality of
transmitting
rods respectively inserted into the radial holes of the third flange of the
transmitting
race; an integrally formed outer race located out of the transmitting race and
having a
plurality of wave grooves on the inner periphery thereof; and the same
plurality of balls
respectively provided between the transmitting rods and the wave grooves of
the outer
race in order to rail on the wave grooves.
According to one aspect of the present invention, the sleeve is integrally
formed
with the input shaft.
According to the other aspect of the present invention, the first to third
bearings
are ball bearings, and the transmitting rod has a circular cross-section.
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Preferably, a semi-spherical recess is formed on one side of each transmitting
rod so that the corresponding ball is positioned in the recess.
Preferably, the same plurality of rollers are respectively provided between
the
third bearing and the transmitting rods, and a groove is formed on one side of
each
transmitting rod so that the corresponding roller is positioned in the groove.
Preferably, a pair of fourth bearings is provided between the outer race and
the
transmitting race, and the fourth bearings are respectively assembled around
the first
and second flanges of the transmitting race.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects and advantages of the present invention will get
readily apparent with reference to the following detailed description when
considered in
conjunction with the accompanying drawings wherein:
FIG. 1 is an exploded perspective view showing a transmitting unit according
to a
preferred embodiment of the present invention;
FIG. 2 is a cross-sectional view showing the transmitting unit according to
the
preferred embodiment of the present invention; and
FIG. 3 is a cross-sectional view that is taken along the line A-A of FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Hereinafter, preferred embodiments of the present invention will be explained
in
detail with reference to the attached drawings.
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FIG. 1 is an exploded perspective view showing a transmitting unit according
to a
preferred embodiment of the present invention. FIG. 2 is a cross-sectional
view for
showing the transmitting unit according to the preferred embodiment of the
present
invention, and FIG. 3 is a cross-sectional view that is taken along the line A-
A of FIG. 2.
Referring to FIGs. 1 and 2, a transmitting unit according to a preferred
embodiment of the present invention includes an input shaft 110 driven by a
driving
device 100, a transmitting race 130, and an outer race 150.
The input shaft 110 has a conventional key groove 112, and as shown in FIG. 2,
the driving device 100 is assembled to the input shaft 110 by a key (not
shown).
i p A sleeve 120 is integrally formed with the input shaft 110, and has a
first
concentric portion 122, a second concentric portion 124, and an eccentric
portion 126.
As shown in FIG. 1, the first and second concentric portions 122 and 124 and
the
eccentric portion 126 are integrally formed.
If the sleeve 120 is integrally formed with the input shaft 110 as in the
present
15 invention, a separate sleeve is not needed. Thus, the number of parts of
the unit is
decreased and the unit can be minimized.
A first bearing 142 is assembled along the outer periphery of the first
concentric
portion 122, and a second bearing 144 is assembled along the outer periphery
of the
second concentric portion 124. And, a third bearing 146 is assembled along the
outer
20 periphery of the eccentric portion.
The first and second bearings 142 and 144 support the third bearing 146, and
reduce the frictional speed when the transmitting race 130. The third bearing
146 is
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eccentrically moved when the input shaft 100 is driven.
According to the present invention, ball bearings are used as the first to
third
bearings 142, 144, and 146 in a transmitting unit for light load, and ball
bearing are
used as the first and second bearings 142 and 144 and a roller bearing is used
as the
third bearing 146 in a transmitting unit for heavy load. But, roller bearings
may be used
as the first to third bearings 142, 144, and 146.
The integrally formed transmitting race 130 is installed on the outer
peripheries
of the first and second bearings 142, 144, and 146. The transmitting race 130
has a first
flange 132, a second flange 134, and a third flange 136. According to an
aspect of the
present invention, the transmitting race 130 is integrally formed.
The first flange 132 surrounds the outer periphery of the first bearing 142,
and
the second flange 134 surrounds the outer periphery of the second bearing 144.
The
third flange 136 surrounds the third bearing, and is integrally formed with
the first and
second flanges 132 and 134. As shown in FiG. 1, the third flange 136 has a
plurality of
l5 radial holes that are spaced apart by a predetermined distance.
Transmitting rods 140 are inserted into the radial holes 137 of the third
flange
136 of the transmitting race 130, respectively. The transmitting rods 140 are
movable in
a radial direction in the radial holes 137, and have a circular cross-section.
As shown in FIG. 1, a plurality of engagement holes 135 are formed on the
front
surface of the second flange 134. An output shaft (not shown) is assembled to
the
engagement holes 135 by a flange-type engaging appliance (not shown).
The outer race 150 surrounds the outer periphery of the transmitting race 130,
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and has a plurality of wave grooves 152 on the inner periphery thereof, as
shown in FIG.
3.
According to the preferred embodiment of the present invention, the wave
grooves 152 are disposed in a row, but may be disposed in a pair of rows.
Balls 160 are provided between the transmitting rods 140 and the wave grooves
152 of the outer race 150 and roll on the wave groove 152. A semi-spherical
recess 143
is formed on one side of each transmitting rod 140 so that the corresponding
ball 160 is
positioned in the recess 143.
According to the present invention, the balls ~ 60 roll between the
transmitting
l0 rods 140 and the outer race 150, which reduces the frictional forces,
compared to the
case rollers roll between them. On top of that, the balls can endure axial
loads.
The wave groove 152 is designed such that the balls 160 make surface contact
with the wave grooves 152 when rolling on the wave grooves 152. Therefore, the
contact stress in the balls 160 during the operation of the unit is given out,
and thus the
! 5 lives of the balls are prolonged.
Rollers 147 are provided between the third bearing 146 and the transmitting
rods
140 respectively, a groove 145 is formed on one side of each transmitting rod
140 so
that the corresponding roller 147 is positioned in the groove 145.
The outer race 150 is integrally formed, and a pair of fourth bearings 170 are
20 provided between the transmitting race 130 and the outer race 150. As shown
in FIG. 2,
the fourth bearings 170 are assembled around the first and second flanges 132
and
134 of the transmitting race 130. In the preferred embodiment of the present
invention,
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bail bearings are used as the fourth bearings 170.
The fourth bearings 170 support the loads of the transmitting race 130 during
the
transmission on both sides of the transmitting race 130, and thus minimize the
deformation of the input shaft 110. Therefore, the precision of the assembly
maintained
even during the operation of the unit, and the vibration and the noise are
minimized.
Hereinafter, the operation of the above-mentioned transmitting unit will be
explained with reference to FIGs. 2 and 3.
Firstly, after the input shaft 110 of the transmitting unit according to the
present
invention is assembled to the driving device 100, the driving force is
transferred to the
input shaft 110 from the driving device 100. When the driving force rotates
the input
shaft 110, the rotational force is transferred to the first to third bearings
142, 144, and
146.
When the input shaft 110 is rotated, the eccentric portion 126 of the sleeve
120
integrally formed with the input shaft 110 is rotated, moving between a and b
of FIG. 3.
Therefore, the driving force of the input shaft 110 and the rotational force
of the
eccentric portion 126 are transferred to the third bearing 146.
As mentioned above, the third bearing 146 is eccentrically rotated, and thus
the
transmitting rods 146 are reciprocated in the holes 137.
The ball 160 provided on one side of each transmitting rod 140 rolls along the
wave groove 152 of the outer race 150, and simultaneously the transmitting rod
140
rotates the transmitting race 130.
Then, since the transmitting rods are symmetrical with reference to the
central
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point of the input shaft 110. as shown in FIG. 3, when the ball 160 of the
transmitting
rod 140 which is located on the upper side of the unit is located at a highest
point 152A
of the wave groove 152, the ball 160 of the transmitting rod 140 which is
located on the
lower side of the unit is located at a lowest point 1528 of the wave groove
152.
According to the operation of the unit, if the input shaft 110 is rotated, the
output
shaft (not shown) assembled to the transmitting race 130 is rotated at a
reduced
rotational speed.
As stated above, preferred embodiments of the present invention are shown and
described. Although the preferred embodiments of the present invention have
been
IO described, it is clearly understood that the present invention should not
be limited to
these preferred embodiments but a variety of changes and modifcations can be
made
by one skilled in the art within the spirit and scope of the present invention
as
hereinafter claimed.
15 INDUSTRIAL APPLICABILITY
As described above, the transmitting unit based on the present invention has
an
integrally formed transmitting race, an integrally formed outer race, and an
input shaft in
which an eccentric portion is integrally formed, without using a separate
eccentric
sleeve, and thereby the causes of the assembly tolerances are basically
settled.
?0 Therefore, since the unit is precisely maintained, the operation of low
vibration and low
noise can be easily achieved. Furthermore, according to the unit of the
present
invention, the life of the unit becomes prolonged, and the strength of the
unit is
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maintained. Since the number of parts becomes remarkably reduced, the
manufacturing cost of the unit could be reduced.
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