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Патент USA US3095969

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July 2, 1963 ,
T. -H. TÓEPPEN
A
INDEXING CLUTCHES
AFiled Feb. 19„,1962
FIGA _
3,095,959
`
2 sheets-sheet 1 '
2j
INVENTOR
Julif 2, 1963
T. H. 'TOEPPEN
INDExING cLuTcHEs
Filed Feb. 19, 1962
ÈÉS
f' l C@
1
-.
3,@95ß59
Patented July 2, 1963
2
In the drawings:
FIG. l is an enlarged, partially-sectioned elevation
3,095,959
INDEXHNG CLUTCHES
Thurston H. Toeppen, Mahopac, N.Y.
(RJ). 3, Lois Lane, Poughkeepsie, N.Y.)
showing the left end of a typical typewriter platen, with
the clutch mechanism in the engaged condition.
FIG. 2 is an enlarged end View showing a section taken
along the plane 2_2 of FIG. l.
FIG. 3A is an enlarged, partially-sectioned elevation
Filed Feb. 19, 1962, Ser. No. 173,986
7 Claims. (Cl. 197-123)
This invention relates to indexing clutches of the type
used to adjust and maintain the angular relationship be
showing the details of the actuating mechanism, with the
clutch in the disengaged condition.
tween a rotatable member and a fixed reference member,
or between two rotatable members, »by means of a slidable
FIG. 3B is similar to FIG. 3A, but shows the clutch in
the engaged condition, as in FIG. 1.
FIG. 4 is a diagrammatic end View showing how a
coaxial control shaft. In the particular embodiment here
in described, it is shown as applied to a typewriter platen
single-point connection between the three primary clutch
clutch for line adjustment of the angular position of the
members will permit excessive play at most points on the
platen with respect to the typing point; however it may
of the ratchet, even though the clutch iS
be used in a variety of other applications for adjusting the 15 ycircumference
engaged.
relative position of a rotatable member accurately and
FIG. 5 is an end View taken along the plane 5_5 of
positively, in very small increments, and by means of a
_FIG. 3A, with the clutch cover shown in partial section
comparatively small actuating force.
to reveal how a second connection-zone may be added to
In the design of typewriter carriages it is customary to
provide the work-holding platen with a coarse-pitch 20 y prevent the excessive play illustrated in FIG. 4.
ratchet wheel which serves both as a means of maintain
Construction
ing the platen in a >given angular position, by means of a
detent member fastened to the supporting frame, and as
a means of rotating the platen to a new position.
In
addition, it is customary to provide a manually-controlled
clutch between the ratchet wheel and the platen itself, for
As shown in FIGS. l `and 2, all of the clutch elements
25 are mounted on an endwise extension of platen body 1.
'The extension is in the form of a cylindrical shell 2,
coaxial with the platen body. Expandable clutch ring 3
llits loosely around Vthe outside of shell 2.
typing point.
Ratchet ring 4 in turn surrounds clutch ring 3. In the
Clutches for the latter purpose are generally operated 30 disengaged condition there is a small clearance between
by a coaxial shaft extending from the left end of the
.them so that the ratchet ring is free to rotate with respect
platen, and although they may be controlled in a variety
,to the clutch ring, but when the clutch ring is expanded
of Ways it is generally accepted that a spring-return push
slighly, in a manner to be described, they become firmly
locked together as in FIG. l.
button control having a short stroke and requiring a com
paratively small operating force is the preferred form.
Expansion and contraction of ring 3 is controlled by the
Clutches of this type may be adjustable either by lixed 35 .operation of crank levers 5 and 6, which are moved sim-ul
increments, usually in steps of about 1/32 inch, or infinitely
taneously by the axial motion of actuator yoke 7, which
variable; that is, adjustable by increments of any desired
is a part of release :shaft 8. Shaft 3 is normally biased in
size. The infinitely-variable type is preferred because of
an outward direction by the pressure of spring 9* against
its greater accuracy and versatility, `but has been used to 40 .terminal button :10, so that spring 9 provides all of the
only a small extent in practice because of the diiiiculty of
force required to cause the engagement of clutch ring 3
r'with ratchet ring 4.
meeting all the necessary performance requirements at a
cost comparable with that of _the incremental clutch.
Cover 11 is fastened to extension shell 2 by means of
more accurate positioning of the work with respect to the
It is an object of this invention to provide an improved
infinitely-variable indexing clutch.
It is also an object of this invention to provide an im
proved platen clutch for typewriter use.
It is also an object of this invention to provide an in
dexing clutch having high torque when engaged, low
four screws 12, and serves to retain and position the other
It is recessed into ratchet wheel 4, and carries an
45 parts.
integral hollow stern 13, which 4supports the platen in the
carriage frame. Stem 13 also serves to guide shaft S, and
supports the inner end of spring 9‘ as well as platen knob
14
torque when disengaged, low force and travel require 50 The two principal problems which have been associated
ments for discriminating between the two conditions, an
with use of an expandable-ring element in clutches of this
infinite number of engagement points, no relative displace
class are (l) providing mechanically eliîcient motion
ment of the clutch surfaces during engagement, and no
transfer from the actuating stem to the ring, and (2) pre
perceptible backlash between the clutching members after
vention of backlash and assurance of dependable opera
engagement.
It is also an object of this invention to provide the de
sired performance characteristics in a compact, durable
and economical form.
Other objects of the invention will be pointed out in the
55 tion without the use of individual adjustments and/ or ex
cessively close tolerances. The way in which these prob
lems have been solved will now be described.
Actuatíng Mechanism
following description and claims and illustrated in the 60
In a typical application, the input motion of the release
accompanying drawings, which disclose, by way of ex
shaft, which may be approximately M1”, must be trans
ample, the principle of the invention and the best mode,
lated radially about 1/2”, rotated 90°, and divided equally
which has `been contemplated, of applying that principle.
between yboth faces of the cut in the clutch ring. In addi
Brieñy, the objects of this invention are accomplished
by the use of a split-ring clutch element which normally 65 tion, the motion must -be reduced by a factor of l5 or
more and the actuating force multiplied to the maximum
possible amount. If there were no frictional losses, the
panded to grip firmly on the inner surface of the platen
force obtained would be inversely proportional to the
ratchet wheel. Novel means are provided for expanding
motion reduction, but since local pressures on some of
the ring in the most eiiicient manner, for anchoring the
tends toward a contracted condition, but which can be ex
ring to the body of the platen without transient displace 70 the bearing surfaces are relatively high, reduction of fric
tion is lamong the key problems. As shown in FIGS. 3A
ment, and for preventing backlash in the clutch after en
` gagement.
and 3B, friction has been reduced to a negligible amount
by use of a pair of rolling-contact cam surfaces 15 and 16,
_
3,095,959
"
,
3
.
.
4
Y
on adjacent end portions of crank levers 5' and 5 respec-
vangles of crank rotation and more favorable dimensional
tively.
relationships.
Cranks 5 and 6, which are of hard material, are supY ported at each end by shell 2 and clutch Aring 3, in such
a way as to permit maximum precision of operation at
minimum cost of construction, as described below
(FIG. 2).
.
The end l17' of crank 5, opposite cam end 15, serves
as the primary anchor point for clutch ring 3, in addition "
tofbeing a simple pivot for crank S. It extends through
holes in shell Zand ring 3, both of which fit end 17 as
closely as possible without binding it. The corresponding
end 18 of crank 5 is also a close fit in ring 3, but passes
through a clearance notch or hole 19 in shell Z; this
Iarrangement positions the ends of both cranks accurately
while eliminating the need Ifor close tolerances in posi
tioning the holes.
The cam surfaces at ends l5 and 16 may be made by
cutting or forging small flat areas on the round wires of
_which cranks 5 and 6 are made; other suitably-shaped
cam surfaces may also be used.
When terminal button lil is fully depressed, in oppo
sition to the force of spring 9, shaft 8 and yoke 7 depress
cranks S and 6 to corresponding Vpositions as shown in
F‘IG. 3A.
In this condition, the cam surfaces are par
allel, the width of slot 20 in clutch ring 3 has contracted
‘to its mini-mum and is in contact with the ñat surfaces
lt will also be noted that :both the crank systems and
clutch ring 3 are laterally symmetrical With respect to a
common centerline midway between cranks S and 6. Con
sequently, expansion of ring 3 takes place equally in both
directions, so that there is no tendency for ratchet ring
4 to be displaced in either direction while the clutch is
engaging.
Backlash Control
The mechanism described above serves to clamp clutch
>ring 3 firmly to ratchet wheel 4, but does not adequately
lock either of -them to shell 2. It has been shown that
crank end 17 provides a precisely-controllable connec
tion between the three elements along a common line
which is nearly radial to the platen axis. However at
all the other points around the ring sufficient space must
be provided to accommodate tolerance variations among
the various parts; consequently, although there may be
very little tangential play between shell 2 and wheel 4
at the anchor point, the ratchet wheel is still lfree to os
cillate about this point as shown in FIG. 4, resulting in
a substantial amount of tangential play at `a point 4’ dia
metrically opposite, and lesser amounts in between, as at
points 4". In addition wheel 4 is free to slide along 4the
pivot axis of crank 5, to the extent permitted by the
various diametral clearances.
These undesirable motions can be suppressed by the
so that it is slightly smaller than the inside diameter of
provision
of la secondary «anchor point, spaced approxi
30
mately 120° from the main one. To this end, clutch
«ratchet ring d.
iIn this condition the clutch is disengaged so that
ring 3 is made wide enough that it projects into a shallow
ratchet ring d can revolve freely with respect to platen
Vrecess 27 in cover lil, as shown in FIGS. 3B and 5.
body 1. When button it? is released, spr-ing '9 reverses
The radius of »this recess is larger than 4the inside di
the loads through the train of parts; as yoke 7 moves out
35 ameter of wheel 4 at all points, except in the immediate
ward, crank end 15 rotates clockwise and end 16 coun
vicinity of the secondary anchor point as shown in FIG.
terclockwise so that they maintain rolling contact with
'5. In this area 2?» the radius is reduced sufficiently that
each other and with both surfaces of slot 20. During
»the thickness of material is equal to or slightly greater
this process they roll from their minimum dimension con
than the distance from the clutching surface 29 of wheel
dition toward their -maximum dimension condition, ex 40 4 to the `cover recess surf-ace 30 of the same part. There
panding slot 2d and ring 3 in the process, until they are
ifore, as clutch «ring 3 is expanded, the small ‘sector 28 of
stopped by the buildup of pressure between rings 3 and
cover 11 (which is effectively a part of shell 2), is
-4. The contact surfaces of slot Ztl must be of hard
clamped firmly between ring 3 and wheel 4, preventing
material; it is not essential that the entire ring be hard
any relative motion at that point without signiñc-antly im
45 pairing the total gripping torque of the clutch and with*
ened.
I-t will be noted that _as the cam surfaces rotate together
out requiring inconvenient tolerance restrictions on the
the crank ends are also translated slightly in the direc
parts. The combination of two »anchor points reduces
tion of yoke movement, as shown in FlGS. 3A and 3B.
backlash to the point where it usually cannot be de
The fit of pivot ends 17 and 1S must allow for this
tected except by instruments.
movement. It is also necessary to provide means for 50
Equalizer 21 land guide hole 23' can serve as index
keeping ends 15 and “i6 in proper phase with each other
points to insure that sector 28 is properly located during
so they do not slide out of position while rolling. This
assembly of the cover.
is done by equalizer 21, which is slipped over the round
While «there have been shown and described ‘and pointed
portions of cranks 5 and 6 just inside of shell 2. The
out the fundamental novel «features of the invention as
lower stem of the equalizer slides in a hole 22 in shell 2, 55 applied to a prefer-red embodiment, it will be under
and the upper stem slides in a hole 23 in cover 11 so that
stood that various omissions and substitutions and changes
‘the equalizer can only move parallel to shaft 8. Since
in the form and details of the device illustrated and in
‘slot 24 is perpendicular to this motion and is a bearing
its operation may be made by those skilled in the art,
tit on the round sections of cranks 5 and 6, it is free to
without departing from the spirit of the invention. It is
move with the rolling motion of the crank ends.
60 the intention, therefore, to be limited only as indicated
In addition, spring 25 maintains a `small inward pres«
by the scope of .the following claims.
-of the cams, and the diameter of ring 3 is at a minimum
sure on the equalizer so that the cams will always move
to the same rest position, against support surface 26,
which is part of shell 2, when the clutch is disengaged.
`This assures that the cams will remain within their de
signed range of travel during operation. Aside from
support surface 26, the opening in shell 2 may be of
any convenient shape so long as it does not interfere
with the motion of the crank ends.
`It »will be noted that the inner pivot axes of cranks 5
and 6 are transposed with respect to the outer axes.
What -is claimed is:
,
.
l. An indexing clutch comprising a principal support
member, an expandable clutch .ring «surrounding said sup
65 port member, a mating external friction ring mounted for
relative rotation with respect to said clutch ring, and
'engaging means for selectively interlocking said clutch
ring, said external ring and said support member, said
engaging means comprising a symmetrical pair of cam
70 elements -in rolling contact with each other and with hat
cooperating surfaces of said clutch ring, means mounting
The principal object of thi-s arrangement is to cause the
'translation of crank ends l5 and i6 to be in the same
direction as the motion of shaft 3. in addition it per
mits longel lever arms for the cams, 4resulting in smaller 75
said cam elements loosely on said support member, a
slidable openating member mounted within said support
member for coaxial movement relative thereto, and means
responsive to the axial movement of said operating mem
3,095,959
ber for simultaneously rolling said cam elements along
said cooperating surfaces of said cintch ring to expand the
clutch ring into frictional engagement with the external
ring.
2. An indexing clutch as in claim 1, in which said pair
of cam elements are in the form of double-ended cranks,
said cranks having cam surfaces at one end in rolling
contact with each other and with said iiat cooperating snr
faees of said clutch ring and cylindrical pivot surfaces at
the other end pivotally engaged in said support member,
6
the crank ends during operation, said positioning and
equalizing means comprising a slidable member having a
transverse slot embracing said crank ends adjacent to said
cam surfaces, and spring means urging said slidable mem
ber and said crank ends toward the disengaged position,
means for limiting the displacement of said clutch ring
with respect to said principal support member, said limit
ing means comprising aligned bearing holes in sai-d support
‘ e axes of the center portions of said cranks being later
member and said clutch ring and wherein fan extension of
the pivot end of at least one of said cranks extends through
ally oiiset from the pivot axes thereof, said center portions
of said cranks operably engaging said means responsive
said aligned holes, and wherein there is provided addi
tional means for limiting the displacement of said clutch
to the axial movement of said operating means to eiiect
a combined pivoting and linear travel of said cam surfaces.
3. An indexing clutch as in claim 2, having means for
ing means comprising a slidable member having a trans
verse slot embracing said crank ends adjacent to said cam
ring relative to said support member after clutch engage
ment, said additional limiting means comprising a small
portion of said support member interposed between said
clutch ring and said external friction ring at a point
»approximately 120° from said crank pivot extension, a
slidable operating member mounted within said support
member for coaxial movement relative thereto, and means
responsive to the axial movement of said operating mem
surfaces, and spring means urging said slidable member
ber for simultaneously rotating said cam elements in
positioning said cam surfaces in the disengaged condi
tion and for equ-alizing the rolling displacements of the
crank ends during operation, said positioning and equaliz
engagement with each other to expand the clutch ring
into frictional engagement with the external ring.
6. In a typewriter platen structure, an indexing clutch
as in claim 1 wherein the principal support member is a
platen core, an end cover disposed in axially spaced
relation to said platen core and connected thereto, and
an external friction ring in the form of a ratchet wheel
tional means for limiting the displacement of said clutch
ring relative to said support member after clutch engage 30 disposed in the space between said platen core and said
end cover and freely mounted for rotation on said end
ment, said additional limiting means comprising a small
cover, said ratchet wheel being in turn adjustable by ûxed
portion of said support member interposed between said
increments with `respect to its carriage frame.
clutch ring and said external friction ring at a point
7. in a typewriter platen structure, an indexing clutch
approximately 120° from said crank pivot extension.
as in claim 5 wherein the principal support member is a
5. An indexing clutch comprising a principal support
platen core, an end cover disposed in Iaxially spaced rela
member, an expandable clutch ring surrounding said sup
tion to said platen core and connected thereto, and an
port member, a mating external friction ring mounted for
xternal friction ring in the form of a ratchet wheel dis
relative rotation with respect to said clutch ring, and
posed in the space between said platen core and said end
engaging means for selectively interlocking said clutch
and said crank ends toward the disengaged position.
4. An indexing clutch as in claim 2, wherein said sup
port member and said clutch ring are provided with
aligned bearing holes and wherein an extension of the
pivot end of at least one of said cranks extends through
said aligned holes and wherein there is provided addi
-ring, said external ring and said support member, said 40 cover and freely mounted for rotation on said :end cover,
said ratchet wheel being in turn adjustable by fixed incre
ments with respect to its carriage frame.
elements in the form of double-ended cranks, said cranks
engaging means comprising a symmetrical pair of cam
having cam surfaces at one end and cylindrical pivot sur
faces at the other, the axes of the center portions of said
References Cited in the iile of this patent
cranks being laterally `o?líset from the pivot axes thereof, 45
means for positioning said cam surfaces in the disengaged
condition and for equalizing the rolling displacements of
UNITED STATES PATENTS
923,016
1,511,776
Carhart ______________ __ May 25, 1909
Roberts ______________ __ Oct. 14, 1924
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