Expansible chamber devices – Sealed opening in longitudinal wall of chamber for receiving...
Reexamination Certificate
1998-11-23
2001-02-13
Lopez, F. Daniel (Department: 3745)
Expansible chamber devices
Sealed opening in longitudinal wall of chamber for receiving...
Reexamination Certificate
active
06186049
ABSTRACT:
The invention relates to a piston rod-less (herein referred to as a rod-less) linear drive comprising a housing, which delimits a interior space extending in the longitudinal direction, in which a drive part is arranged for longitudinal movement and which has a slot-like longitudinal opening directed into the said housing interior space, such opening being flanked in the longitudinal direction on either side by a housing limb which is constituted respectively by a portion of the housing, an entraining part being arranged on the drive part, such entraining part extending outward through the longitudinal opening, such entraining part being kinematically coupled with a slide outside the housing, such slide being guided by means of a guide means for movement in the longitudinal direction in relation to the housing and being supported in the transverse direction.
Such a rod-less linear drive is for example disclosed in the European patent publication 0 540 015 B1. In the case of this drive the guide means arranged on the outer side of the housing limb, which is to the top in the preferred position of use of the linear drive, such limb being straddled by the slide cooperating with the guide means. On the top side of the section, which straddles the housing limb, of the slide a carrying face is provided which serves for the attachment of the load to be conveyed. In order to reduce the effect, due to the force of the weight of the load to be conveyed, on the housing the slide is additionally supported by a wheel running on a support face arranged on the other housing limb. Despite this supporting action there is however still the danger of slight deformation of the housing limb having the guide means in the case of extremely heavy loads to be conveyed, something which leads to a reduction in the width of the longitudinal opening and hence which may cause the development of wear promoting friction between the flanks of the longitudinal opening and the entraining part. The deformation furthermore impairs the accuracy of alignment of the slide, which may then run slightly skew. The same disadvantageous effective will occur, if the housing expands owing to internal pressure, in which case it may even happen that the slide lifts clear of the additional support face.
Therefore it is one object of the present invention to provide a rod-less linear drive, which, independently of the load to be conveyed, runs extremely accurately with little wear while at the same time having a compact structure.
In order to achieve this object in the invention one of the two housing limbs is extended in the depth direction of the longitudinal opening past same and on the side facing the other housing limb, of its extension section bears the guide means with the slide, this other housing limb being uncoupled from the slide as regards loads.
In the device of the invention independently of the size of the load to be conveyed by the slide deformation of the interior space in the housing and of the longitudinal opening is prevented. At the same time there is always an extremely high accuracy of guiding as regards the slide to be moved. If the linear drive is operated in its preferred position of use, wherein the side bearing the guide means faces upward, all forces necessary for guiding and support are taken up by the extended housing limb. The other shorter housing limb is decoupled from the slide and consequently is not acted upon by the load to be conveyed. Accordingly there is no possibility of constriction of the longitudinal opening due to the weight force of the load to be conveyed and accordingly no wear resulting from this. Moreover the accuracy of guiding will not suffer because of a splaying out, caused by a high internal pressure, of the housing, since the housing limb, decoupled from the slide, may deform without acting on the guide means or the slide.
Although the European patent publication 0 711 928 A2 discloses a rod-less linear drive, in the case of which the guide means is so arranged on the one housing limb that it is placed in the preferred position of use adjacent to the interior space of the housing and the danger of deformation of the housing is banished, this is only possible at the sacrifice of having the guide means arranged with a transverse clearance laterally adjacent to the longitudinal opening and of the having to have the slide fitting over the housing part with the interior space in the housing so that as measured in the depth direction of the longitudinal opening there is a i substantial overall height. On the other hand the configuration of the invention renders possible an arrangement, in the case of which the housing part having the interior housing space and the slide are placed alongside one another with only a small overall height, since because of the entraining part and owing to the alignment, facing the guide means, of the longitudinal opening there is a direct connection by the drive part and the slide.
Further advantageous developments of the invention are defined in the dependent claims.
It is convenient for the slide to be arranged in a receiving region of the housing, which in the depth direction of the longitudinal opening adjoins the longitudinal opening and at one side is delimited by the extension section. It is in this manner that it is possible to have particularly small dimensions in the height direction.
It is an advantage if on the side opposite to the extension section the slide bears a carrying face serving for the attachment of a load to be moved, and generally aligned parallel to the extension section, such carrying face being adjacent to the short housing limb. More particularly the carrying face can be arranged at the same level as the outer face of the short housing limb in order to provide a particularly low overall arrangement. In this respect there may be a provision such that the above mentioned outer face is slightly exceeded in level by the carrying face in order to ensure that a load with a large surface area arranged on the carrying face can extend past the carrying face in the transverse direction without then being obstructed by the housing.
It is furthermore convenient for the guide means to comprise a guide rail extending in the longitudinal direction of the housing and provided on the extension section, and furthermore a guide body provided on the slide, the guide body being mounted on the guide rail for motion in the longitudinal direction thereof while at the same time being supported in the transverse direction. Owing to the guide means, which can be produced without any great expense, a satisfactory guiding action in the longitudinal direction is ensured, which simultaneously is able to withstand the transverse forces occurring.
Because an anti-friction bearing arrangement is placed between the guide body and the guide rail, for instance in the form of a recirculating ball slide, it is possible for the frictional forces between the guide body and the guide rail to be substantially reduced so that even in the case of heavy loads it is possible to ensure free running properties of the guide body along the guide rail.
In a further convenient embodiment the drive part is constituted by a fluid operated piston, a flexible sealing tape being provided effectively adjacent to the inner side of the longitudinal opening in order to seal off such opening. Such so-called slotted cylinders are in practice highly satisfactory for linear drives, particularly when high accelerations of the slide are required.
REFERENCES:
patent: 4664020 (1987-05-01), Kaiser
patent: 5330272 (1994-07-01), Stoll
patent: 5555789 (1996-09-01), Rosengreen et al.
patent: 5701798 (1997-12-01), Noda
patent: 804 632 (1951-04-01), None
patent: 0 370 157 A1 (1988-11-01), None
patent: 0 540 015 A2 (1992-10-01), None
patent: WO 92/17321 (1992-10-01), None
Angue Eric
Stoll Kurt
Festo AG & Co.
Hoffman & Baron LLP
Lopez F. Daniel
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