Note: Descriptions are shown in the official language in which they were submitted.
2167889
--AN OUTPUT MEMBER OF A LINEAR DRIVE--
The invention relates to an output member of a linear
drive arranged between the two ends of a traction means, as for
example a toothed belt, trained around reversing elements and adapt-
ed in operation to perform a linear movement caused by the
driven traction means in the longitudinal direction of the
housing of the linear drive, ends of the two traction means
ends being respectively attached to the output member by means
of a connecting device.
The German patent publication 4,016,867 A1 discloses a
linear drive, which comprises a toothed belt running around
bend elements in the form of gear wheels and having ends se-
cured by means of connecting device in the form of screw fas-
tening means to a drive output member, which can be coupled
with a load to be moved. The necessary preliminary tension of
the toothed belt functioning as the traction means is set by
the connecting devices, which possess chocks engaged with the
toothed belt and able to be set with the aid of screws in rela-
tion to the output member.
The adjustment of the tension of the traction means is a
comparatively elaborate operation in the known linear drive.
For this purpose a screwdriver must be used between the runs of
the toothed belt. Furthermore the known design of an output
drive member is hardly able to be designed as a component em-
ployed in very small linear drives, since the limits of minia-
turization are rapidly reached.
Accordingly it is one object of the present invention to
provide an output drive member of the type initially mentioned,
which also renders possible a presetting of the desired tension
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of the traction means even in the case of small sizes of
equipment.
According to the present invention there is provided an
output member of a linear drive arranged between the two ends
of a traction means trained around reversing elements and
adapted in operation to perform a linear movement caused by
the traction means in the longitudinal direction of a housing
of the linear drive, two ends of the traction means ends being
respectively attached to the output member by means of a
connecting device, wherein said output member is designed in
the form of a tensioning and connecting link for the traction
means and for this purpose is divided into two link elements
respectively associated with one of the ends of traction means
and able to be locked in a closed setting against one another
corresponding to a desired degree of tension of the traction
means, the link elements respectively possess a guide section
extending within a longitudinal recess, open on the
longitudinal side, in the housing and connected by means of
one of the connecting devices with one of the ends of the
traction means and also possess a closure section arranged
clear of the longitudinal recess, the link elements
overlapping at least at their closure sections laterally in
the longitudinal direction, for steplessly adjusting the
tension of the traction means, the link elements are coupled
together in a longitudinally sliding fashion using
longitudinal guides, and the link elements are able to be
fixed together, in order to set them in the closed setting, at
the overlapping parts of the closure sections.
It is in this manner that the invention provides an
output member which prior to assembly is in two parts, each of
such parts termed link elements being able to be fixed to one
end of the respective traction means. It is then only
necessary to place the traction means, fitted with the link
element in this manner, in the linear drive and to unite the
tensioning and connecting link by attachment together of the
link elements. In this respect the variable closed setting of
the link is an advantage because it renders possible the
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preset of the different degrees of tension in the traction
means or can be employed to allow for inaccuracies in
manufacture. The link elements mating with each other by
means of the longitudinal guides, may be slid together until
the desired value of a preset tension is reached in order to
then lock the closed setting, arrived in this manner, using
suitable fastening means acting between overlapping portions
of the closure sections. Since the zone of locking may be
placed clear of the longitudinal recess, it
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is conveniently accessible so that the tensioning and connect-
ing link is simple to manipulate. The design in accordance
with the invention of the output drive member renders possible
the production of links with a small overall size, this being
something facilitating miniaturization.
Further advantageous developments of the invention are
defined in the claims.
It is preferred for the longitudinal guides to be groove
and tenon arrangements which are simple to manufacture.
The operation of closing the novel connecting and
tensioning link is simplified if at least during the terminal
part of the sliding movement the link elements bear against one
another in all transverse directions. In this case it is suf-
ficient to subject the link elements to a suitable compression
force, there being no necessity for lateral support owing to
the integrated transverse supporting effect.
For the mutual fastening together of the link elements a
screw or pin connection system may for example be provided,
which comprises at least one bolt-like transverse member, which
simultaneously fits in the two overlapping parts of the closing
sections, more particularly by extending through same. The
recesses serving to accommodate the transverse member are pref-
erably arranged in the closing sections, when the desired
closed setting has been reached.
Advantageous further possibilities for fixing the two link
elements in place reside in the production of adhesive and/or
welded joints.
The guide section, cooperating in use with the housing of
the linear drive, of the output drive member is preferably con-
stituted by guide pistons provided on the two link elements,
such pistons being connected with the closure sections by means
of narrow guide ribs.
It is preferred for the two link elements to be identical
in configuration, same expediently being single-piece compo-
nents consisting of plastic.
In what follows the invention will be described with ref-
erence to the accompanying drawings in more detail.
Figure 1 shows a partly broken away view of a first
design of the output drive member in accor-
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dance with the invention together with a
linear drive equipped with it.
Figure 2 is a longitudinal section taken through
the arrangement illustrated in figure 1
looking in the direction of the arrow II
in figure 1.
Figure 3 is a separate lateral elevation of the
drive output member in accordance with
figures 1 and 2, the closure section of
the right element being shown broken away
so that the reader is free to partly see
the overlapping portion of the left link
element.
Figure 4 is a cross section taken through the
output drive member of figure 3 taken on
the section line IV - IV.
Figure 4 shows a cross section taken through the
output drive member of figure 3 on the
section IV - IV.
Figure 5 shows the output drive member in a
separate view in which the link elements
are still separate in the disconnected
state prior to fastening the output drive
member functioning as a connecting and
tensioning link.
In figures 1 and 2 the reader will perceive an electric
motor driven linear drive 1. It possesses an elongated
housing 2 with a suitably designed cross section, which at the
ends is provided with a respective cover 3 and 3'. In each
cover there is a reversing or bend element 4 and 4', here in
the form of a rotatably mounted gear wheel. The one bend
element 4 is mounted for free rotation. The other bend
element 4' is drivingly connected with an electric motor 5,
which is more particularly flange mounted on the side of and
on the associated cover 3.
A filamentary traction means 6 is trained around the bend
elements 4 and 4'. It is able to yield in the transverse
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direction and in the present case is in the form of a toothed
belt, which meshes with the two bend elements 4 and 4'.
Instead of such traction element it would be possible to
utilize a means in the form of links, as for instance a chain,
or some other
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~- 216789
element in the form of a band or tape.
The traction means 6 possesses two runs 7 and 8, which
extend parallel to one another and are both aligned in the lon-
gitudinal direction of the housing 2. The one run 7, which is
lower down in terms of figure 2, is continuous and extends in a
groove-like recess 13, running in the longitudinal direction
12, in the housing 2. It is accordingly sunken in the housing
2. The longitudinally extending mouth of the recess 13 can be
covered by a rail-like cover 14. The entry of the first run 7
in the two covers 3 and 3' to reach the two bend elements 4 and
4' is through suitable openings in the covers 3 and 3".
The second run 8 of the traction means 6 is interrupted.
The two ends 15 and 15', produced by having such interruption,
of the traction means are secured to an intermediately placed
output drive member 16 so that in all there is a loop-like or
continuous arrangement around the bend elements 4 and 4'.
The output drive member 16 possesses a coupling section 17
to the side of and outside the housing 2 and which is adapted
for coupling with a load to be moved. This load, which is not
shown in detail, may be secured to the coupling section 17 di-
rectly or with suitable intermediate connecting elements. For
instance it is possible for the load to be moved to be attached
to a guide carriage, not illustrated, which is connected with
the coupling section 17 and bears against an external longitu-
dinal guide.
During operation of the linear drive 1 the traction means
6 is driven With the aid of the electric motor 5 to perform a
circulating movement, which results in a linear movement of the
output drive member 16 in either of two possible directions of
motion along the longitudinal axis 12. The load coupled with
the output drive member 16 will move accordingly.
In the case of a further possible embodiment, not illus-
trated here, the drive force is supplied by the action of a
fluid on a piston driven to perform a movement, such piston
being arranged intermediately in the first run 7.
In order to ensure a certain amount of lateral guiding
action for the output drive member 16 the same has a guide part
18 thereof running in a longitudinal recess 23, open on the
longitudinal side toward the external surface 22 of the hous-
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2167889
ing, in the housing 2. The second run 8 of the traction means
6 extends in the interior of this longitudinal recess 23 in
parallelism to same. The ends 15 of the traction means are
attached to the guide part 18.
The longitudinal recess 23 in the present instance pos-
sesses a transversely widened section 24, which is placed at a
lower level than the external surface 22 of the housing, such
section 24 preferably having a circular cross section. It is
for example cylindrical in form. The connection with the ex-
ternal surface 22 of the housing is also in the form of a slot-
like, narrow section 25 extending also in the longitudinal di-
rection i2. This section 25 is covered over from the outside
by a cover tape 26, which prevents ingress of dirt and at the
end is secured to the two covers 3 and 3'. The output drive
member 16 comprises an axially continuous opening 27, which has
the cover tape 26 extending through it and possesses the curved
form as shown in figure 3, which means that during longitudinal
motion of the output drive element 16 the cover tape 26 is lo-
cally lifted clear of the slot-like section 25 adjacent to the
output drive member.
The output drive member 16 serves not only to transmit
force to the outside, but also constitutes a connecting and
tensioning link for the traction means 6. The output drive
member 16 is employed during assembly of the traction means 6
in order to connect together the two ends 15 and 15' of the
traction means 6 to form a closed loop thereof.
As is more particularly indicated in figure 5, the output
drive member or connecting and tensioning link 16 is composed
of two link elements 28 and 28', in the case of which it is a
question of separate components in the undone or open position
illustrated here. The two link elements 28 and 28' are, in
accordance with an advantageous design, made integral, and are
more particularly in the form of injection molded synthetic
resin parts. Both the link elements 28 and 28' are furthermore
made identical, something which reduces costs.
The two ends 15 and 15' of the traction means are respec-
tively secured to the respective ends of the link elements 28
and 28', more particularly in a detachable manner. In the case
of the connecting means 32 employed in the present case it is
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2167889
preferred not to employ screw connecting means as they would
hinder miniaturization.
Each link element 28 and 28' possesses a guide section 33,
which is received within the longitudinal recess 23 allowing
longitudinal movement. The same comprises in the present em-
bodiment a guide piston 34 running in the widened section 24
and a narrower guide rib 35 adjoining same radially outward.
The guide rib 35 extends through the slot-like section 25. It
is adjoined by a closure section 36 and 36' placed outside the
longitudinal recess 23.
The ends 15 and 15' of the traction means are respectively
connected by a connecting means 32 with the one guide piston 34
permanently. The connecting means 32 in the present embodiment
possesses a slot-like recess 37, running in the plane of the
traction means 6, which is open on one longitudinal side (at
44) and toward the rear end surface 38 of the guide piston 34.
For the example the lower internal surface, which faces the
closure section 36 and 36', bears a linear toothed structure
43, which is complementary to the toothed structure of the
traction means 6. The height of the recess 37 is generally
equal to the thickness of the traction means 6, which by way of
the longitudinal side opening 44 (arranged on the cylindrical
surface of the guide piston 34) is thrust sideways into the
recess 37. The traction means 6 has its full width within the
guide piston 34, while at the rear end surface 38 its section
leading to the first run 7 it projects outward. It is in this
manner that the respective end 15 and 15' of the traction means
is positively and grippingly held on the respective link ele-
ment 28 and 28'. In order to lock the connection it is possi-
ble as well to provide a securing or locking ring 45 on a ter-
minal collar on the guide piston 34, which holds together the
piston sections divided by the recess 37 and furthermore sur-
rounds the traction means 6. There is accordingly a very sim-
ple connecting means 32, not requiring the use of screws, which
may also be employed on output drive members 16 of small over-
all size.
In order to apply the tension to the traction means 6,
slung around the bend elements 4 and 4' as is necessary for
operation, it is unnecessary, and indeed impossible, to perform
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2167889
any adjustment to the connecting means 32. The desired tension
of the traction means is set by a greater or lesser axial move-
ment together of the two link elements 28 and 28', into which
the output drive member 16 is subdivided. During assembly of
the traction means 6 on the linear drive 1 the link elements 28
and 28' attached to the ends 15 and 15' of the traction means
are shifted from the initial open position into a closed posi-
tion as indicated in figures 1 through 4, in which same are
fixedly joined together. In this state they complement each
other to form the output drive member 16.
On closing the connecting and tensioning link 16 the link
elements 28 and 28' are slid together linearly as indicated by
the arrows 46 with their front sides leading. The farther the
link elements 28 and 28' are thrust together, the greater the
tension in the connected traction means 6. It is convenient if
the link elements 28 and 28' are thrust together using a suit-
able measuring device until the desired tension has been
reached. In this position of sliding, referred to as the
closed position, larger or smaller axial intermediate spaces 47
may be present between the axially facing surfaces of the link
element 28 and 28'.
The arrangement illustrated by way of example is so de-
signed that the guide sections 33 do not overlap in the closed
position. The two guide pistons 34 and the two guide ribs 35
adjoin each other in an aligned fashion, forming the above men-
tioned guide part 18, which is only divided axially at an in-
terruption 48, such interruption possibly comprising an inter-
mediate space 47.
The closure sections 36 and 36' are so designed that in
the closed position they overlap each other laterally in the
longitudinal direction 12 which coincides with the direction 46
of sliding. The closure sections 36 and 36' are generally
elongated in form, same extending from the rear side of a re-
spective link element 28 and 28', i. e. from the vicinity of
the rear end surface 28 linearly forward, a front part 49
thereof extending axially past the front side of the associated
guide piston 34. For instance each respective closure section
36 and 36' is approximately twice as long as a respective guide
section 33.
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The two closure sections 36 and 36~ complement one another
in the closed position to give the coupling section 17. In
this respect the overlapping parts 53, which are in the form of
rails, overlap, same resting laterally against each parting
plane 52 extending in the longitudinal direction 12 between the
overlapping parts 53 which extend in parallelism to the plane
of circulation of the traction means 6 and preferably centrally
as well. The front end surface 54 of a respective overlapping
part 52 will then be opposite to a limiting surface 55, which
is provided on a part 56, preferably acting as an abutment por-
tion, formed by a rear end region of the respectively other
closure section 36 and 36'. Between the surfaces 54 and 55
extending athwart the longitudinal direction 12 the said inter-
mediate spaces 47 may be located, although it is to be noted
that the two link elements 28 and 28' may also be in direct
contact with one another given a suitable closed position adja-
cent to the intermediate spaces 47.
In plan view and looking from an external point toward the
output drive member 16, each closure section 36 and 36' as
shown in the present embodiment, will be seen to possess an L-
like configuration, the longer L limb forming the overlapping
part 53, which is aligned in the longitudinal direction 12 and
the shorter L limb forming the abutment part 56 extending in
the transverse direction.
In order to ensure that the adjustment of the tension in
the traction means may be performed simply, the link elements
28 and 28' are connected together by means of cooperating lon-
gitudinal guides 57 and 57' while allowing longitudinal sliding
motion. The gresent embodiment possesses two pairs of posi-
tively cooperating longitudinal guides 57 and 57', which are
preferably in the form of interlocking groove and tenon ar-
rangements 58. On the lower edge of the front part 49 each
overlapping part 53 possesses an inwardly open guide groove 59
into which there fits a guide rib 60 arranged on the other link
element in the transition part between the guide section 33 and
the closure section 36 and 36'
During the first part of the displacement of the guide
contact the link elements 28 and 28' can be lifted clear of
each other without any difficulty. As soon as however they are
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21678~~9
drawn together a certain extent, further cooperating longitudi-
nal guides 61 and 61~ become effective, which are responsible
for a transverse supporting action right the way round so that
there is now only one degree of freedom, i. e. freedom of axial
shift.
In the illustrated working embodiment of the invention the
longitudinal guides 61 and 61' serving for transverse support
comprise bolt-like spurs 62 and recesses 63 cooperating togeth-
er in pairs. On the front end 54 of a respective overlapping
part of a respective overlapping part 53 a lug 62, which may
also be termed a spur, is arranged which projects axially, it
being opposite to a recess 63 provided on the part 56 of the
respectively other link elements 28 arid 28'. On sliding the
link elements 28 and 28' together during the last part of move-
ment one respective lug 62 of the one link element 28 and 28'
will fit axially into a complementary recess 63 in the other
link element 28' and 28. With the exception of the axial di-
rection the link elements are accordingly locked and unmovable.
The abutment part 56 present in the path of displacement
of a respective overlapping part 53 may also contribute to pre-
venting excessive stretch during the tensioning operation.
This protective function may however also be assumed by the
facing front end surfaces 54 of the guide sections 33, in which
case the abutment part 56 may simply have the purpose of making
available a locking recess 63 for the lugs 62 and the trans-
verse locking, caused thereby, of the two link elements 28 and
28'
It would be feasible to provide longitudinal guides simul-
taneously performing a transverse supporting action. Thus the
link elements 28 and 28' could for example be coupled together
by means of longitudinally extending dovetail guides. In the
illustrated working embodiment it would be feasible furthermore
to dispense with the groove and tenon arrangements 58 and only
to provide the further longitudinal guides 61 and 61' to have a
sliding guiding action for the link elements 28 and 28~.
In order to arrest the link elements 28 and 28' in the
set, closed position, certain attachment means are provided
between the overlapping parts 53. In the embodiment of the in-
vention the attachment means involves the production of a pin
21~~88~
connection 66, in which at least one pin transverse member 67
simultaneously interlockingly fits into both overlapping parts
53. This provision is preferably made by holding the two over-
lapping part 53 after reaching the closed setting and jointly
drilling through the same so that two aligned openings 68, in-
dicated in broken lines in figure 5, are obtained, into which
the transverse member 67 may then be inserted or pressed.
Instead of having a pin connection 66 it would also be
feasible to have a screw or rivet joint, a releasable joint
offering the advantage of it being possible to readily replace
the traction means 6 after failure thereof.
In the case of a further embodiment, not illustrated, the
attachment means between the two link elements 28 and 28' could
be a bond or a welded joint, preferably an ultrasonic weld.
The bonded or welded surfaces would then conveniently be the
lateral surfaces, facing one another in the parting plane 52 ,
of the overlapping parts 53.
Preferably the positions of separation of the two link
elements 28 and 28' are so placed that for the entire length
thereof there is a longitudinal division of the opening 27,
through which the covering tape 26 extends, such that the open-
ing 27 is longitudinally open in the open position of the con-
necting and tensioning link. Both link elements 28 and 28'
possess limiting surfaces 69 and 69', which in the fitted to-
gether state of the link elements 28 and 28' cooperate together
to form the inner surface of the opening 27. In the illustrat-
ed working embodiment the opening 27 extends adjacent to the
two closure sections 36 and 36', whose overlapping parts 53
constitute the lateral surfaces of the opening 27. The base
surface 73 of the opening is preferably predetermined on the
guide section 33.
In the illustrated working embodiment the coupling section
17 possesses a plurality of transverse holes 70, which render
possible the attachment of a load to be moved. For the same
reason the pin-like transverse member 67 is designed in the
form of a sleeve.
At least one of the guide pistons 34 may possess a recess
71, in which a magnet part 72 is rotatably mounted belonging to
a position detecting device of the linear drive 1.
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2167889
Since the two closure sections 36 and 36' assume positions
outside the longitudinal recess it is readily possible to take
hold of them, clamp them and attach them to one another. Ac-
cordingly it is unnecessary for the user to place his hand in
the close vicinity of the traction means.
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