U.S. patent number 3,828,893 [Application Number 05/308,652] was granted by the patent office on 1974-08-13 for servo-drive positioning device.
This patent grant is currently assigned to The National Cash Register Company. Invention is credited to Thomas R. Clark.
United States Patent |
3,828,893 |
Clark |
August 13, 1974 |
SERVO-DRIVE POSITIONING DEVICE
Abstract
A linkage connects an off-center point of a motordriven assembly
to a pivot point on a reference or frame member and is used for
holding a movable member in a fixed position relative to the
reference member. The linkage includes a double-locking clutch with
two sets of springloaded washers carried on a shaft in canted
manner, and a pair of opposed plungers positioned between the sets
of washers to maintain position of the washers on the shaft. A
small force applied to a trigger sleeve, which encloses the clutch,
unlocks one set of the washers to release a locking sleeve to move
in the direction of the applied force and thereby adjust the
position of the locking sleeve in relation to the reference member,
and when the force is removed, the locking sleeve is locked on the
shaft in a self-centering position.
Inventors: |
Clark; Thomas R. (Utica,
MI) |
Assignee: |
The National Cash Register
Company (Dayton, OH)
|
Family
ID: |
23194844 |
Appl.
No.: |
05/308,652 |
Filed: |
November 22, 1972 |
Current U.S.
Class: |
188/67;
248/354.1; 74/531 |
Current CPC
Class: |
B41J
15/02 (20130101); Y10T 74/2066 (20150115) |
Current International
Class: |
B41J
15/02 (20060101); B65h 059/10 () |
Field of
Search: |
;188/67 ;248/355 ;74/531
;254/105,106 ;403/104 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Halvosa; George E. A.
Attorney, Agent or Firm: Cavender; J. T. Hawk, Jr.; Wilbert
Muckenthaler; George J.
Claims
What is claimed is:
1. A positioning device comprising a shaft and journal means
therefor, said shaft being connected to a reference member, locking
means including a sleeve slidable on the shaft and a
plurality of elements spaced along and cantably carried on said
shaft for gripping thereof and securing said sleeve thereon,
resilient means diametrically positioned for urging said plurality
of elements into a locked position on said shaft,
means for releasing said plurality of elements from their locked
position and permitting movement of said locking sleeve and said
elements along said shaft, said releasing means including an
actuating sleeve operably associated with said locking sleeve for
moving thereof along said shaft to a new position in relation to
said reference member, and
means for centering said releasing means in relation to said
locking means upon movement of said locking sleeve to said new
position, said means for centering including a lost-motion
connection between said locking sleeve and said actuating sleeve
and opposing resilient means for urging said actuating sleeve to a
centered position in relation to said locking sleeve.
2. The device of claim 1 wherein said lost-motion connection
includes elongated apertures in said actuating sleeve for
permitting said opposing resilient means to move said actuating
sleeve to its centered position.
3. A positioning device for a servo-assembly, said device
comprising a
shaft and journal means therefor, said shaft being connected to a
reference member,
locking means slidably carried on the shaft and including a sleeve
and a plurality of washer elements,
resilient means including a plurality of springs on opposite sides
of the shaft and positioned to urge said washer elements into a
canted position to lock said sleeve and said elements on said
shaft,
means for releasing said locking means from said shaft, said
releasing means including an actuating sleeve encircling said
locking means, and yoke means connected with said locking sleeve
and engageable with said actuating sleeve for movement thereof,
and
means for centering said actuating sleeve in relation to said
locking sleeve, said centering means including a lost-motion
connection operably associating said actuating sleeve and said
locking sleeve and spring urged plungers positioned to center said
actuating sleeve in relation to said locking sleeve after movement
of said locking sleeve to a new position.
4. The device of claim 3 wherein said lost-motion connection
includes elongated apertures in said actuating sleeve for
permitting said plungers to move said actuating sleeve to its
centered position.
5. Means for adjusting and retaining position of a servo-assembly
in relation to a reference member on a business machine, said means
comprising a shaft pivotally connected to said reference
member,
clutch means including a locking sleeve having opposed sets of
washer elements spaced along the shaft and lockable thereon,
means for resiliently urging the opposed sets of washer elements
into locking engagement on said shaft, said resilient urging means
including a plurality of springs diametrically positioned adjacent
said shaft,
means for releasing the opposed sets of washer elements from
locking engagement with the shaft to thereby permit pivoting of
said servo-assembly and movement of said locking sleeve to a new
position on said shaft, said releasing means including a trigger
sleeve with end mounted elements and yoke means connected with said
locking sleeve and engageable with said trigger sleeve for movement
thereof, and
means for centering of said trigger sleeve in relation to said
locking sleeve, said centering means including a lost-motion
connection between said locking sleeve and said trigger sleeve and
a pair of opposed spring loaded plungers connected between the end
mounted elements for centering of said trigger sleeve in relation
to said locking sleeve after adjustment of the locking sleeve to a
new position.
6. The subject matter of claim 5 wherein said lost-motion
connection includes elongated apertures in said actuating sleeve
permitting said pair of spring loaded plungers to move said trigger
sleeve to its centered position.
Description
BACKGROUND OF THE INVENTION
In the matter of positioning and retaining the position of
mechanical devices, which are subject to forces not contemplated
within a system, there have been ways and means for controlling the
position of one member relative to another member. In this respect,
the use of springs, plungers, and like devices have been used for
maintaining various elements in adjustment where such devices can
be used in an assembly. The spring loading feature and associated
structure, as well as hydraulic or dash-pot devices, may also be
utilized in similar circumstances to control or to adjust one
element in relation to another. Normally, such structure takes on
the concept of providing means for maintaining position of a
movable member relative to a fixed member, while permitting
adjustment of the movable member under certain conditions.
Closer to the present invention is the concept of a rod carrying a
slidable member abutting a cylinder wherein the slidable member
assumes a canted position to retain the cylinder along the rod,
such as is commonly used in door closers.
SUMMARY OF THE INVENTION
The present invention relates to positioning devices and more
particularly to a linkage mechanism connected to a reference member
and to an assembly for adjusting certain parts of the assembly in
relation to the reference member. The linkage mechanism
incorporates a double-locking clutch with two sets of spring-loaded
washers carried on a shaft in canted manner and a pair of opposed
plungers positioned between the sets of washers to maintain
position thereof. A slidable locking sleeve encircles the washers
and a portion of the shaft, and the washers, when in the canted
position, prevent relative motion between the locking sleeve and
the shaft, except when it is desired to make an adjustment.
A small force is applied in one direction to a trigger or actuating
sleeve and thereby releases one set of the locking washers from the
shaft to permit movement of the locking sleeve along the shaft to a
new position. The locking sleeve follows the motion of the trigger
sleeve in the direction of the applied force and when once the
force is stopped, the locking sleeve will be locked on the shaft
with the trigger sleeve recentering itself in relation to the
locking sleeve. The construction of the present invention and the
action obtained therefrom permit a self-centering of the trigger
sleeve when the new adjustment position is reached.
In line with the above discussion, the principal object of the
present invention is to provide a positioning device which performs
fine-tuning adjustment.
Another object of the present invention is to provide a linkage
mechanism for connecting a servo assembly to a reference member for
remote control of adjustment.
An additional object of the present invention is to provide a
positioning device for adjusting printing mechanism along a print
line.
A further object of the present invention is to provide spring
loaded plungers and sets of washers for locking of a cylinder along
a shaft.
Another object of the present invention is to provide resilient
means between the several members for recentering of the actuating
member after adjustment of the positioning device.
Additional features and advantages will become apparent from a
reading of the following specification taken together with the
annexed drawings, in which:
FIG. 1 is a side elevational view of a portion of servo mechanism
incorporating the subject matter of the present invention;
FIG. 2 is a sectional view taken on the line 2--2 of FIG. 1;
FIG. 3 is an enlarged sectional view of a portion of FIG. 2;
FIG. 4 is an end view of the positioning device;
FIG. 5 is a sectional view taken on the line 5--5 of FIG. 4;
FIG. 6 is a sectional view taken on the line 6--6 of FIG. 4;
FIG. 7 is a sectional view taken on the line 7--7 of FIG. 4;
FIG. 8 is a sectional view similar to FIG. 6 and showing a slightly
different position of the parts thereof; and
FIG. 9 is an enlarged view taken on the line 9--9 of FIG. 3.
Referring now to FIGS. 1 and 2 of the drawings, there is shown
certain structure including a motor shaft for a servo assembly
which assembly has one application for positioning and controlling
the position of printing mechanism when printing on form paper or
the like. As is well known, continuous form paper is used in high
speed printing apparatus, the form paper being driven by tractor
mechanism past a print station wherein character or other indicia
printing may be accomplished in line manner. As is also well know,
it is extremely important that the printing position on the paper
be controlled to the extent that, because of pre-printed lines on
the paper, the printed characters or other indicia are maintained
evenly spaced and in a straight format across the paper.
Additionally, after certain periods of operation, there may be a
tendency for the paper to inch ahead or fall behind during the
travel thereof in relation to the printing mechanism. This becomes
even more important when the paper includes such pre-printed lines
thereon and it is desired to print in precise manner between the
lines. Of course, should the paper have the tendency to become
slightly displaced in relation to the printing mechanism, there
must be provided means for adjusting the line of print so as to
maintain an exact format of line printing.
The present invention is considered important as a part of a drive
assembly which performs a stepping operation by driving the paper a
line at a time. In this respect a servo mechanism drives the paper
forward in stepping manner so that the paper is successively
positioned for printing on each succeeding line.
The present invention is directed to means for re-positioning or
adjusting the drive mechanism in those instances when the drive
line veers from a correct position and such drive mechanism
includes a motor shaft 10 driven by a servo motor 12 supported from
machine framework in the nature of a flange, the major portion of
surrounding framework being omitted from the drawing for reason of
clarity. Shaft 10 is carried in bearings located inside the motor
in conventional manner, and the shaft carries a pivotable casting
40 upon bearings 16 and 18, and within such casting carries a gear
cluster 20 for meshing with a second gear cluster 22 on a shaft 24
parallel to shaft 10, the shaft 24 being supported in suitable
bearings in the casting 40. In other words, the casting 40 is
solely supported from the shaft 10, which extends from and is
supported from the motor 12, which, in turn, is flange mounted to
the machine frame. The purpose of the gear clusters 20 and 22 is to
provide for the printing of either 6 lines or 8 lines per inch,
with the gears shown in the 6 lines per inch position. One end of a
bowden wire 26 is for the purpose of changing the line spacing from
6 to 8 lines. Gear cluster 22 has connected thereto an optical disk
28 used in the control system, which is not a part of the present
invention.
The shaft-supported casting 40 furthermore has legs 42 and 44 (FIG.
2) extending downwardly and connected to a positioning device 50
carried on a rod or shaft 52 pivotally supported at one end thereof
to a clutch anchor pivot 54 connected to a framework 56 so as to
provide a reference member for the device 50. The device 50 is
constructed to be slidable along the rod 52 in relation to the
reference member 56 in operation of which will be further
described. Sliding movement of the device 50 along the rod 52 is
accomplished by means of a link or arm 58 connected to the device
50 and extending to a control lever (not shown).
In FIG. 3 is shown an enlarged sectional view of the positioning
device 50 with the rod or shaft 52 in the center thereof, and the
legs 42 and 44 connected to the device by means of studs or
shoulder screws 60 and 62 threaded into the body of the device
midway between the ends thereof. It is thus seen that the location
of device 50 on shaft 52 determines the angular position of casting
40 about its support shaft 10, within desired adjustment limits.
FIG. 4 shows an end view of the positioning device with certain
parts similar as FIG. 3. The link 58 connects to a shoulder 70 on
the device 50 and the other end connects to the manually
positionable control lever, not shown. A washer 71 is disposed
between the leg 42 and the exterior surface of the device 50.
Referring now to FIG. 5, the positioning device 50 is carried by
the shaft 52 and includes a locking sleeve 72 adjacent the shaft,
the sleeve assuming the shape of a "T" in cross-section thereof and
providing a recess 74 in the vicinity of each end for reception of
a set of washers 76 and a set 78. The two sets of washers are
positioned on the rod 52 in such manner as to be capable of being
slightly canted thereon for purposes to be described. The support
for the shaft 52 in the device 50 is derived from a pair of hubs 80
and 82 over the ends of which are cover plates 84 and 86,
respectively, the plates being retained in position by means of
coil springs 90 attached to the cover plate at each end of a
cylinder 92 and stretched along the periphery thereof. The cylinder
92, which generally comprises a sleeve, encloses the parts in
compact manner with screws 94 securing the shaft support hubs 80
and 82 with the locking sleeve 72. Additionally, a pair of
adjusting screws 98 and 100 (FIG. 6) are threaded into the
respective cover plates 84 and 86 and through respective openings
101 and 102 in the hubs 80 and 82 to position the ends of the
screws adjacent the sets of washers 76 and 78. A nut 103 is carried
by the screw 98 to be disposed against the cover plate 84 and a
similar nut 104 is on screw 100 and against plate 86 to provide for
the adjusting action of the ends of the screws in relation to the
sets of washers.
The two sets of washers 76 and 78 are position controlled along the
shaft 52 by means of four spring-loaded locking plungers 110,
(FIGS. 6 and 8) a pair of which are axially aligned and
diametrically opposite from a second pair, also axially aligned,
and engaging the sets of washers on one side thereof in opposing
manner by a pair of springs 109. A pair of stop pins 111 and 112
are secured in the support hubs 80 and 82 in position directly
opposite the adjusting screws 98 and 100.
An additional feature of the present invention provides for
self-centering of the trigger sleeve 92 in relation to the locking
sleeve 72 after the adjusting action is completed. This is
accomplished by means of a pair of centering plungers 115 and 116
loaded by a spring 117 and having stems 118 and 119 engageable with
the cover plates 84 and 86, respectively (see FIGS. 6 and 8). This
structure, in effect, provides a self-centering concept in the
design to bring the trigger sleeve 92 to a new home position in
relation to the locking sleeve 72. This is an important feature in
that it maintains, while the device is in a holding condition, a
finite gap between screw 100 and washers 78 and between screw 98
and washers 76 so that minute machine vibrations will not cause
gradual loss of position due to "creep" (see FIG. 6). As seen in
FIG. 9, the trigger sleeve 92 includes an elongated slot 125
through which extends the shank 126 of stud or screw 60. A similar
slot 127 on the opposite side of the sleeve 92 from the slot 125
accommodates the shank 128 of stud 62 (FIG. 7) so as to permit
clearance for the self-centering featured parts. The screws 126 and
128 fit tightly in the locking sleeve 72 but freely pivot in the
casting bosses 42, 44, as shown.
In the operation of the device, wherein a typical application is in
a line printer wherein it is desired to maintain registration of
the line of print hammers with the pre-printed lines on continuous
form paper or the like, the normal stepping action of the paper
advancing mechanism can be position adjusted at any point in time.
Once the paper has started through the printer, it is extremely
difficult to advance or retard the continuous form, so it is
necessary to pivot the movable assembly in relation to the machine
frame. Since, as mentioned above, the servo-drive assembly is
supported by bearings 16 and 18 on the motor shaft 10 or an
extension thereof, te assembly must be restrained against rotation
during advancement of and stopping of the motor because of the
torque and counter torque action. Additionally, the motor is
prevented from a reversing or backing action against a one-way
clutch (not shown) to maintain position of the drive mechanism. In
the present instance, it may be necessary to pivot the servo-drive
assembly up to 22.degree. in either direction by means of the
remote control handle, in order to adjust the line of character or
other indicia printing to register with the pre-printed lines on
the paper. The positioning device 50 is intended to hold the
movable servo-assembly at a fixed position in relation to the
machine frame, and therefore the relative paper stopping point, and
to resist any forces tending toward relative motion of the movable
assembly; however, when so desired, the assembly may be moved to a
new "fixed" position and thereheld in the new position against all
forces tending to act thereon.
The device acts as a link connecting the off-center point on the
movable assembly to the pivot point on the machine frame, and
therefore the locking sleeve 72 must not slide on the shaft 52. It
must resist forces tending to make the link longer or shorter,
except when an adjustment is required. When a small force is
applied to the trigger sleeve 92, a slight relative lost motion
occurs between the trigger sleeve 92 and the locking sleeve 72, by
reason of the elongated slots 125 and 127 in the trigger sleeve,
which motion permits the locking sleeve 72 to be unlocked and to
move freely along the shaft 52. This establishes a new length for
the link and a new annular position for the movable assembly. When
the small force is removed from the link by stopping movement of
the control handle, the locking sleeve is bi-directionally locked
in the new position.
The principle is based upon the sets of wasers being canted on the
shaft and retained in position by the spring loaded plungers, the
stop pins and the adjusting screws. In FIG. 6 is shown the locked
position of the device with the sets of washers 76 and 78 being
held in the canted position on the shaft 52. A small force on the
arm or link 58, say to the right in FIG. 6, acts on the hub 70 to
move the locking sleeve 72 to the right. This movement straightens
the washers 78 on the shaft and permits such washers to be moved
therealong, while at the same time the movement of the locking
sleeve 72, along with the action of the plungers 110, straightens
the washers 76 by reason of the frictional effect of the washers 76
against the shaft 52. When the new position is reached, the control
handle is released and the locking sleeve 72 is again locked on the
shaft 52 and the washers 76, 78 are urged to the canted position.
The self-centering plungers 115, 116 then return the trigger sleeve
92 to the new home position so that no forces can prevail against
the locking sleeve 72 until the next adjustment is made.
It is therefore seen that herein shown and described is a
positioning device which utilizes canted washers on a shaft, and is
controlled by spring-loaded plungers to effect adjustment of
position of the locking sleeve along the shaft. The trigger sleeve
centers itself in the new position so that the locking sleeve is
not affected by forces derived from operation of the drive means
for the stepping action, and so that vibrations of the trigger
sleeve related linkage are not communicated to the locking washers.
The apparatus enables the accomplishment of the objects and
advantages mentioned above, and while only one embodiment of the
invention has been disclosed herein, certain variations may occur
to those skilled in the art. It is contemplated that all such
variations, not departing from the spirit and scope of the
invention, are to be construed in accordance with the following
claims.
* * * * *