Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Reexamination Certificate
1999-10-12
2001-05-22
Green, Mary Ann (Department: 3682)
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
C074S436000
Reexamination Certificate
active
06234047
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an intermittent transmission mechanism for converting a continuous rotational displacement into an intermittent rotational displacement for transmission.
2. Description of the Prior Art
As an example of intermittent transmission mechanism of this type, a Geneva drive mechanism has been proposed which is disclosed in Japanese Utility Model Publication Kokai H6-40507. As shown in
FIG. 8
of this reference, this apparatus includes a driven rotor
03
having engageable elements in the form of a plurality of slots
02
opening radially outwardly. The plurality of slots
02
and a plurality of recesses
01
are arranged alternately at predetermined intervals peripherally of the driven rotor
03
. Further, a driving rotor
06
has an engaging element in the form of an engaging roller
04
for sequentially engaging the plurality of slots
02
of driven rotor
03
to rotate the driven rotor
03
intermittently by a predetermined angle. The driven rotor
03
has also a plurality of freely rotatable rotating rollers
05
attached thereto for contacting arcuate surfaces
01
a
of the recesses
01
of driven rotor
03
when the driven rotor
03
stops with the engaging roller
04
disengaged from the slots
02
.
In the Geneva drive mechanism having the above construction, the number of slots
02
formed in the driven rotor
03
corresponds to the number of intermittent rotations (hereinafter called dividing number) per complete rotation of driven rotor
03
. When the driving rotor
06
rotates to engage the engaging roller
04
in one of the slots
02
of driven rotor
03
, the driven rotor
03
is rotated until the engaging roller
04
becomes disengaged from the slot
02
. The rotation of driven rotor
03
is stopped until the engaging roller
04
engages a next slot
02
disposed upstream in the direction of rotation of the slot
02
from which the engaging roller
04
is disengaged
When the rotation of driven rotor
03
is stopped, the rotating rollers
05
of driving rotor
06
rotate in contact with the arcuate surface
01
a
of non-drive recess
01
of driven rotor
03
, and move with the driving rotor
06
along the arcuate surface
01
a.
With the conventional intermittent transmission mechanism in the form of a Geneva drive mechanism, when the driven rotor
03
is stopped, an excessive workload on an output line of driven rotor
03
may be transmitted back to the driven rotor
03
as a strong torque. This strong torque reaction concentrates on support axes
05
a
of the rotating rollers
05
of driving rotor
06
contacting the arcuate surface
01
a
of non-drive recess
01
of driven rotor
03
, or concentrates on a proximal portion of driven rotor
03
lying between the slots
02
adjacent each other in the direction of rotation and having a minimum width W in the direction of rotation. The support axes
05
a
or the proximal portion with the minimum width could be broken.
When the driven rotor
03
is rotated intermittently and the excessive workload on the output line of driven rotor
03
acts as a strong reaction on the driven rotor
03
, the reaction concentrates on a support axis
04
a
of the engaging roller
04
of driving rotor
06
engaged in a slot
02
of driven rotor
03
. Thus, the support axis
04
a
could be broken.
Therefore, in case a great workload occurs on the output line of driven rotor
03
, the support axis
04
a
of engaging roller
04
may be formed with an increased diameter to increase the maximum permissible stress of support axis
04
a
. In this case, however, where only the diameter of support axis
04
a
is simply enlarged, the diameter of engaging roller
04
also is inevitably enlarged. As a result, the slots
02
have an enlarged opening width in the direction of rotation, and the minimum width W of the proximal portions becomes correspondingly small. Actually, therefore, it is necessary to enlarge both a maximum radius R of driven rotor
03
and a distance r from a rotational axis of driving rotor
06
to a center axis of engaging roller
04
. This has resulted in the enlargement of the intermittent transmission mechanism.
In addition, an increase in the number of slots
02
formed in the driven rotor
03
, i.e. the dividing number, reduces an angle of rotation from engagement to disengagement of engaging roller
04
into/from a slot
02
and an engaging depth radially of the direction of rotation. This results in an increase in the maximum radius R of driven rotor
03
, thereby enlarging the intermittent transmission mechanism. Conversely, a decrease in the dividing number increases the angle of rotation from engagement to disengagement of engaging roller
04
into/from a slot
02
and the engaging depth radially of the direction of rotation. This reduces the width of the minimum width proximal portions of the driven rotor, which may cause breakage as noted hereinbefore.
This invention has been made having regard to the state of the art noted above, and its object is to provide an intermittent transmission mechanism, with a devised transmission structure of a driving rotor and a driven rotor, for allowing the dividing number to be set as desired while ensuring improved strength to withstand a workload and a compact construction, and for stopping rotation of the driven rotor with increased precision.
SUMMARY OF THE INVENTION
To fulfill the above object, an intermittent transmission mechanism according to this invention comprises a driving rotor supported to be rotatable about an axis of an input shaft, and a driven rotor supported to be rotatable about an axis of an output shaft parallel to said axis of the input shaft, said driven rotor including a member defining arcuate recesses, and an engageable element, said driving rotor including an engaging element for engaging said engageable element of the driven rotor to rotate said driven rotor intermittently by a predetermined angle, and a cam with a rotation regulating surface movable relative to and along arcuate surfaces of said recesses when said driven rotor is stopped; which is characterized in that said engaging element of the driving rotor is displaced relative to the rotation regulating surface axially of said input shaft, and said engageable element of the driven rotor is displaced relative to said member defining said recesses axially of said output shaft, said engageable element of the driven rotor being in form of a gear defining teeth arranged at predetermined intervals throughout a circumference thereof, and said engaging element of the driving rotor being in form of a partial gear having teeth for meshing with said gear.
According to the above characteristic construction, the partial gear acting as the engaging element of the driving rotor and the partial gear acting as the engageable element of the driven rotor meshed with each other rotate the driven rotor intermittently by a predetermined angle. The two gears mesh in a fixed range radially of the direction of rotation even when the circumferential length of the partial gear (number of teeth) is varied according to the dividing number. Moreover, only the thickness in the direction of the rotational axes has to be considered to assure strength of the teeth. There is no possibility, as in the case of a conventional Geneva drive mechanism, of the strength varying with variations in the radial length of slots resulting from variations in the dividing number, or no need to increase the diameters of the driving rotor and driven rotor for securing strength.
Moreover, since the rotation regulating surface of the driving rotor and the non-driven recesses of the driven rotor are displaced in the direction of the rotational axes from the partial gear acting as the engaging element of the driving rotor and the gear acting as the engageable element of the driven rotor, the meshing between the two gears never adversely affects the intermittent rotation even where the non-driven recesses have a maximum outside diameter of the driven rotor is larger than the outsi
Green Mary Ann
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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