Eccentric orbiting type speed reducer and joint for...

Details Eccentric orbiting type speed reducer and joint for... Eccentric orbiting type speed reducer and joint for...

2001-05-03

2003-02-11

Estremsky, Sherry (Department: 3681)

Planetary gear transmission systems or components

Planet periphery surrounds axis of interacting gear

C475S178000, C475S179000

Reexamination Certificate

active

06517460

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an eccentric orbiting type speed reducer for use with the industrial machine such as an industrial robot or machine tool, and a joint of the industrial machine equipped with the eccentric orbiting type speed reducer, and more particularly to an eccentric orbiting type speed reducer having a plurality of crankshafts in which a rotational force is applied to one of the plurality of crankshafts, and a joint of the industrial machine equipped with the eccentric orbiting type speed reducer.
Conventionally, the joint of the industrial machine equipped with the speed reducer is well-known in which a rotational driving force output from a servo motor is input into a plurality of crankshafts of the speed reducer via a gear supported with the rotational axis on the same straight line as the rotational axis of the speed reducer, as described in JP-A-7-108485, for example.
Referring now to
FIGS. 10 and 11
, a joint
800
of the industrial machine as described in JP-A-7-108485 will be described below.
If a rotational driving force is output from a servo motor
801
, the rotational driving force output from the servo motor
801
is input via a gear
802
into the gears
806
and
807
supported by the bearings
804
and
805
so that the rotational axis may be on the same straight line as the rotational axis of a speed reducer
803
. The rotational driving force input into the gears
806
and
807
is input via a plurality of gears
808
,
809
,
810
and
811
disposed to be mated with a gear
807
into a plurality of crankshafts
803
a
,
803
b
,
803
c
and
803
d
of the speed reducer
803
.
In
FIG. 10
, though the details of the speed reducer
803
are not shown, the speed reducer
803
rotates a body of rotation
820
with respect to an anchor block
830
secured in the floor in accordance with a rotational driving force input into the plurality of crankshafts
803
a
,
803
b
,
803
c
and
803
d
, if the rotational driving force is input into the plurality of crankshafts
803
a
,
803
b
,
803
c
and
803
d.
As described above, the joint
800
of the industrial machine rotates the body of rotation
820
with respect to the anchor block
830
secured in the floor, if the rotational driving force output from the servo motor
801
is input into the plurality of crankshafts
803
a
,
803
b
,
803
c
and
803
d
of the speed reducer
803
.
Also, another joint of the industrial machine equipped with the speed reducer is well-known in which a rotational driving force output from the servo motor is input into a specific crankshaft of the speed reducer, and the remaining crankshafts of the speed reducer via a gear disposed at the top end of the crankshaft having the rotational driving force input and a gear supported so that the rotational axis may be on the same straight line as the rotational axis of the speed reducer, as described in JP-A-9-57678, for example.
Referring now to
FIGS. 12 and 13
, a joint
900
of the industrial machine as described in JP-A-9-57678 will be described below.
If a rotational driving force is output from a servo motor
901
, the rotational driving force output from the servo motor
901
is input via the gears
902
and
903
into a specific crankshaft
905
of a speed reducer
904
, and input into the remaining crankshafts
910
of the speed reducer
904
via a gear
903
disposed at the top end of the crankshaft
905
, a gear
908
supported by the bearings
906
and
907
so that the rotational axis maybe on the same straight line as the rotational axis of the speed reducer
904
, and a gear
909
.
The speed reducer
904
rotates the body of rotation
920
with respect to an anchor block
930
secured in the floor in accordance with a rotational driving force input into the crankshafts
905
and
910
, if the rotational driving force is input into the crankshafts
905
and
910
.
As above described, the joint
900
of the industrial machine rotates the body of rotation
920
with respect to the anchor block
930
secured in the floor, if a rotational driving force output from the servo motor
901
is input into the plurality of crankshafts
905
and
910
of the speed reducer
904
.
Accordingly, in the joint of the conventional industrial machine, since the rotational driving force output from the servo motor is input in equal quantity into the plurality of crankshafts of the speed reducer, it is possible to prevent the life of the speed reducer, particularly, the life of the crankshafts from being shorter.
However, in the joint of the conventional industrial machine as described above, since a rotational driving force output from the servo motor was input in equal quantity into the plurality of crankshafts for the speed reducer, it was required to have a gear supported with the rotational axis on the same straight line as the rotational axis of the speed reducer, and a bearing for supporting the gear. Therefore, there was the problem that the manufacturing costs were increased due to the increased number of parts. That is, in the joint
800
of the industrial machine as shown in
FIGS. 10 and 11
, it is required to have the gears
806
and
807
supported so that the rotational axis may be on the same straight line as the rotational axis of the speed reducer
803
, and the bearings
804
and
805
for supporting the gears
806
and
807
. In the joint
900
of the industrial machine as shown in
FIGS. 12 and 13
, it is required to have the gear
908
supported so that the rotational axis may be on the same straight line as the rotational axis of the speed reducer
904
, and the bearings
906
and
907
for supporting the gear
908
.
SUMMARY OF THE INVENTION
It is an object of this invention to provide an eccentric orbiting type speed reducer that can be manufactured at low costs by preventing an increase in the number of parts, and a joint of the industrial machine equipped with the eccentric orbiting type speed reducer.
According to the present invention, there is provided an eccentric orbiting type speed reducer comprising an internal tooth member having the internal teeth formed on the inner circumference, a first rotational member with a plurality of circular grooves formed inside that is carried rotatably by the internal tooth member, while keeping a coaxial relation with the internal tooth member, a second rotational member with a plurality of circular grooves formed inside, the plurality of circular grooves being opposed respectively to the plurality of circular grooves for the first rotational member, the second rotational member being carried rotatably by the internal tooth member, while keeping a coaxial relation with the internal tooth member, an external gear having the external teeth formed on the outer circumference, with a plurality of through holes formed inside, the external teeth meshing with the internal teeth of the internal tooth member, the external gear being carried between the first rotational member and the second rotational member, a plurality of crankshafts having the first insertion portions to be inserted respectively into the plurality of pairs of opposed circular grooves for the first rotational member and the second rotational member, and the second insertion portions to be inserted respectively into the plurality of through holes for the external gear and orbiting eccentrically the external gear, a plurality of pairs of first bearings for holding the first insertion portions of the crankshafts rotatably with respect to the first rotational member and the second rotational member, respectively, and a plurality of second bearings for holding the second insertion portions of the crankshafts rotatably with respect to the external gear, characterized in that the basic radial load rating of the first bearing into which the first insertion portion of one of the plurality of crankshafts is inserted is greater than the basic radial load ratings of the first bearings into which the first insertion portions of the remaining crankshafts among the plurality of crankshafts ar

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