Expansible chamber devices – Sealed opening in longitudinal wall of chamber for receiving...
Reexamination Certificate
1999-08-03
2001-03-06
Look, Edward K. (Department: 3745)
Expansible chamber devices
Sealed opening in longitudinal wall of chamber for receiving...
C092S169100
Reexamination Certificate
active
06196110
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a linear drive comprising an elongated housing, which possesses a cylinder barrel having a longitudinal slot at one position on its periphery, the interior space of such cylinder barrel being closed at both ends thereof by end caps, of which at least one is designed in the form of a closure plug inserted in the interior space at the end, and further comprising a sealing tape extending in the interior space along the longitudinal slot, such tape axially overlapping at least one closure plug at its exterior periphery.
THE PRIOR ART
A linear drive of this type is for example disclosed in the U.S. Pat. No. 5,701,798. Here it is a question of a linear drive without a piston rod, which comprises a drive part movingly supported in the interior space of the cylinder barrel and which is coupled via an entraining member, which extends through a longitudinal slot in the cylinder barrel, with an external output drive part kinematically. For sealing off the longitudinal slot a sealing tape is provided inside the interior space to extend along the longitudinal slot and is able to rest against sealing faces on the cylinder barrel and arranged adjacent to the flanks of the slot. This sealing tape is terminally secured at the end to the cylinder barrel, it overlapping the closure plug which closes the interior space of the cylinder barrel at the end. The closure plugs are inserted in the interior space for a great part of their length and are fixed in place by externally mounted plate elements.
The known linear drive does suffer from the disadvantage of having a relatively complex fixing means for the closure plugs delimiting the internal space axially. The closure plugs comprise a radially projecting flange and are firstly inserted so far into the internal space that the flange abuts the terminal face of the cylinder barrel. Following this the plate elements are put on and fixed in relation to the cylinder barrel. Finally using clamping screws anchored in the plate elements an axial force is exerted on the closure plugs so that the flange thereof is thrust against the terminal face of the cylinder barrel. Owing to the plate elements so put in place the axial dimensions of the linear drive are unnecessarily increased.
Accordingly one object of the present invention is to provide a linear drive of the initially described type which while ensuring reliable fixing in place of the sealing tape renders possible simple terminal closure of the interior space while ensuring compact longitudinal dimensions.
In order to achieve these and/or other objects appearing from the present specification, claims and drawings, in the present invention the closure plug possesses a flat on the part of its external periphery facing the longitudinal slot, such flat providing a rotational locking effect by engaging the facing internal surface of the sealing tape, the plug being anchored in the cylinder barrel by means of at least one securing pin fitting both into the cylinder barrel and also in the respective closure plug itself, such pin extending athwart the longitudinal direction of the interior space.
In this manner a linear drive is produced, in the case of which no attachment means extending out axially past the cylinder barrel are necessary in order to secure an end plate designed in the form of a closure plug on the cylinder barrel. The closure plug may be completely received in the interior space of the cylinder barrel, at least one securing pin being provided for fixing in position, which pin fits both into the cylinder barrel and also into the closure plug and may be inserted extremely simply without needing much space. In this connection the cooperation of the peripheral flat on the closure plug with the facing internal face of the sealing tape brings about an effect preventing relative rotation of the closure plug so that same may only be inserted with a specific angular alignment into the interior space and therefore automatically assumes a possibly necessary angular alignment for cooperation the securing pin. The angular presetting of position is for example an advantage as well if the interior space is to be supplied through a closure plug with a drive fluid and for this purpose a fluid duct present in the cylinder barrel must assume a position aligned with a fluid duct extending in the cylinder barrel.
Further advantageous developments of the invention are defined in the claims.
It is convenient for an engagement zone provided on the closure plug for the securing pin to be formed by a peripheral groove, which extends over part of the periphery of the closure plug and for example is designed like a notch or a cut. In connection with this it is an advantage if the engagement zone to be located in the peripheral region of the closure plug diametrally opposite the flat. Owing to the measures taken to prevent relative rotation by the cooperation between the flat and the sealing tape it is possible to ensure in this case that the closure plug may only be so inserted in the interior space that the engagement zone provided on it is automatically positioned in the correct setting in relation to the engagement zone, present on the cylinder barrel, for the securing pin. Assembly is now made extremely simple.
In order to be able to position the closure plug, which preferably has no abutment defining the desired depth of insertion, at the desired depth of the penetration in the interior space, it is possible for a recess to be provided on the axial external end of the closure plug, in which recess an assembly tool may be inserted temporarily, and by means of which an axial displacing force may be exerted on the closure plug. It is convenient for such recess to be in the form of a threaded hole such that it may render possible temporary screwing in of the threaded shank provided on the assembly tool, the assembly tool being in the simplest case a commercially available screw.
It is furthermore an advantage for the sealing tape to be fixedly clamped between the flat on the closure plug and at least one clamping face on the cylinder barrel and opposite to the flat for securing the sealing tape to the cylinder barrel. In this respect it is possible the clamping face to be provided on a clamping part fixed externally on the cylinder barrel, such clamping part spanning the longitudinal slot and acting on the external face, turned away from the closure plug radially, of the sealing tape.
In the case of a preferred structure the longitudinal slot has the terminal section, which overlaps the longitudinal slot axially, extending though it completely in the depth direction. In this case the arrangement may be such that the sealing tape projects outward radially to a small extent prior to fitting the clamping part past the cylinder barrel and after fitting the clamping part is acted upon by same and is firmly held between the clamping face and the flat on the closure plug. The clamping part itself may in this case be held by the elastic return force of the sealing tape, which is biased, in position so that it is unnecessary to provide any additional, elaborate measures for fixing the clamping part in place which is more especially plate-like.
A particularly reliable and axially firm means of attachment for the sealing tape is possible if the closure plug has superficial irregularities at its flat, such irregularities being able to come into engagement with the internal face of the sealing tape. This means that it is possible to produce an interlocking connection in addition to the clamping engagement. The superficial irregularities are more especially in the form of teeth.
The linear drive is more particularly a fluid operated structure, an axially moving drive part being arranged in the interior and coupled with an external output drive part, the drive part being in the form of a piston and being coupled with the output drive part via an entraining member extending through the longitudinal slot.
Finally it is to be pointed out that the clamping of the sealing tape between
Festo AG & Co.
Hoffman & Baron LLP
Look Edward K.
Rodriguez Hermes
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