Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Reexamination Certificate
1999-05-19
2001-08-28
Estremsky, Sherry (Department: 3681)
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
C074S096000, C074S089390, C384S007000, C092S00500L, C092S068000
Reexamination Certificate
active
06279411
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a linear drive comprising a rod-like rotationally locked output drive part guided for axial movement in relation to a housing using a bearing means cooperating with its outer periphery, said bearing means being provided in a bearing portion of said housing, at least one position preset element, extending to the side, being provided on the output drive part, such preset element being shifted on axial movement of the output drive part along a position preset space extending alongside the output drive part.
2. Description of the Prior Art
Linear drives of this type are predominantly utilized in assembly and handling operations and are disclosed for instance in the European patent publication 0 219 439 A1. In this known case an output drive part adapted to be driven by the action of fluid to perform a linear movement is provided, which in a bearing portion lying in the front section of a housing, is encircled by a bearing means and is therefore is guided for movement in the longitudinal direction with lateral support. In order to be able to position the output drive part in a predetermined axial position a laterally projecting position preset element is provided laterally projecting from the output drive part, which runs along a lead screw, which is arranged in a position preset space arranged adjacent to the output drive part. Moreover several sensors are arranged in the position preset space adapted to respond to the position preset element and which cooperate with a brake means associated with the lead screw. If during the axial movement of the output drive part the position preset element draws close to one of the sensors, the brake means will be operated by a brake signal so that the lead screw is locked against rotation and a further axial movement of the position preset element and of the output part connected with same will be prevented.
The section, projecting from the housing, of the output drive part is extremely frequently subjected to high transverse forces during operation. For instance the output drive part may be provided with a gripping means, which is to convey heavy loads. It is furthermore possible for further linear drives to be mounted in order to produce a multi-axial handling system. It is therefore necessary to guide the output drive part in relation to the housing along a relatively long bearing portion and to support it in the transverse direction. This leads to a correspondingly larger overall size of the housing.
OBJECTS AND SUMMARY OF THE INVENTION
One object of the present invention is to provide a linear drive of the type initially mentioned, which while ensuring reliable bearing of the positionable output drive part has a compact overall length.
In order to fulfil this object there is a provision such that the bearing means extends for at least one section of its overall length over part of the periphery of the output drive part and the output drive part is exposed in the bearing portion along a section of the periphery not cooperating with the bearing means so that in the bearing portion to the side adjacent to the output drive part there is a free space extending in its longitudinal and peripheral direction, such free space constituting a component, which is available for motion of the position preset element, of the said position preset space.
This means that there is a linear drive, in the case of which the axial shift path available for the position preset element extends into the bearing portion. The axial movement of the position preset element is hence no longer limited by the start of the bearing portion. The position preset space, into which the position preset element extends, and along which such position preset element is moved during the linear movement of the output drive part, is now at least partly extended to include the bearing portion, because the bearing means provided there only extends over a part of the periphery of the output drive part and the output drive part is exposed along a section of the periphery located in the path of movement of the position preset element so that there is a free space in the bearing portion, wherein the position preset element may move without hinderance. The position preset element may therefore be shifted past the effective bearing means into the bearing portion. There is accordingly the possibility of selecting a comparatively long axial bearing portion without thereby overly increasing the overall length of the position preset space, since the position preset space and the bearing means may overlap axially without impeding each other.
Further advantageous developments of the invention are defined in the dependent claims.
If the bearing means extends for its entire overall length over only a part of the periphery of the output drive part, it is possible for a free space increasing the overall length of the position preset space to be provided, which occupies the entire length of the bearing portion.
The bearing means is preferably constituted by at least two diametrally oppositely placed and for instance cassette-like bearing units, which on sides, which are diametrally opposite as related to the longitudinal axis of the output drive part, cooperate with the outer periphery of the output drive part for bearing same. Several such pairs of bearing units can be set in positions distributed in the longitudinal direction of the output drive part on the housing.
Preferably the bearing means simultaneously serves for preventing rotation of the output drive part. If diametrally oppositely placed bearing units are present, the output drive part will preferably have a longitudinally extending guide groove in each of the corresponding potions, into which the respectively associated bearing unit fits in an interlocking manner.
The housing of the linear drive is preferably so designed that in cross section it possesses a rectangle-like configuration. In order in this respect to make optimum use of the overall volume, it is an advantage for the free space for the position preset element to move in is so placed in relation to the transverse and vertical axis of the housing that it has an oblique alignment, it facing obliquely to the side and at the same time downward or upward.
Preferably the bearing means is set on a covering body connected with the base.
It is convenient for the bearing means to be set on main body, having a generally L-shaped cross section, of the housing, the peripheral part of the output drive part facing away from the two L-limbs forming the free space, which is preferably covered over by a cover body connected with the main body, such cover body furthermore covering over the position preset space.
In accordance with a convenient form of the invention the position preset element is designed in the form of an abutment, which cooperates with at least one counter-abutment for presetting the position, such counter-abutment being a component of a position preset means arranged in the position preset space. For position presetting the abutment runs up against a counter-abutment arranged in its path of motion.
The counter-abutments present are conveniently arranged on a holding rod extending in the position preset space in parallelism to the longitudinal axis of the output drive part.
Conveniently the counter-abutments are adapted to be adjusted in the longitudinal direction in order to be able to preset the position as required. In order to ensure optimum centering of the acting force, the abutment is preferably so designed that it at least partly fits around the holding rod more particularly in the manner of a fork.
A modification of the position preset is possible without axially resetting the counter-abutments, if the position preset means has at least one counter-abutment, which may be switched over, using an associated switch-over means, between an active position extending into the path of travel of the abutment and an inactive position located clear of such path of travel of the abutment. It is preferred
Feyrer Thomas
Stoll Kurt
Estremsky Sherry
Festo AG & Co.
Hoffmann & Baron , LLP
Lewis Tisha D.
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