Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
2001-01-19
2002-10-29
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
C292S081000, C292S083000, C384S026000, C074S089320, C074S089360
Reexamination Certificate
active
06472778
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a linear motion unit with a runner that is arranged so as to be movable back and forth along a rod, wherein there is provided in front of and/or behind the runner, in the runner's direction of travel, at least one support unit that supports the rod relative to an essentially rigid counter-element. There is provided on the runner or a unit connected thereto a catch that can be brought into latched engagement with each support unit. The support unit comprises a base body that is longitudinally slidable relative to both the rod and the counter-element in the direction of motion yet is guided in a nonrotating manner with respect to the direction of travel, upon which base body is mounted a control member that can be moved between at least one latched position and at least one released position by means of a control track provided on the counter-element.
The aforementioned support units are usually used with linear motion units of this type in order to prevent sagging or bending of the rod when the length of the rod exceeds a maximum dimension that is a function of its diameter, its construction and the operating conditions to which it is subjected, among other factors. Naturally, the rod is subject to gravity regardless of the precise embodiment of the linear motion unit. In the case of linear drives in which the rotation of a rod embodied as a threaded spindle is translated into a linear motion of a runner including a threaded nut, there are also centrifugal forces acting on the threaded spindle that result from its rotation. Through the use of the support units mentioned, it is possible to keep the unsupported lengths of rod short enough that the sagging and/or bending of the rod between two adjacent support points does not exceed a tolerable amount.
Naturally, the support units must not hinder the movement of the runner. It must therefore be possible for the runner, as it moves in a given direction, to progressively “pick up” the support units located in front of it in its direction of motion. In addition, however, it must also be possible, after the runner reverses its direction of motion, for it to “drop off” the previously collected support units at their intended support locations.
To this end, a type of linear drive has been proposed in EP 0 327 705 B1 in which the support units lock with the counter-element at their intended support positions. To this end, the support units are comprised of a base body that is in supportive engagement with both the rod, which is embodied as a threaded spindle, and the counter-element, which is embodied as a guide rail, and are also comprised of a control slide that is mounted in the base body so as to be movable orthogonally to the longitudinal direction of the threaded spindle. Here, the control slide is spring-preloaded with respect to the base body such that a latch provided on it is pressed against a slideway in which corresponding latch recesses are provided at the predefined support positions. In addition, a catch pin is arranged on the control slide. If the support unit is located in the region of a slide section of the slideway, the catch pin projects upward out of the support unit and engages a catch rail on the runner that carries the support unit along which the runner moves. In contrast, if the support unit is located in the region of a latch recess of the slideway, the latch falls into the latch recess as a result of the spring preloading of the control slide. The catch pin is thereby withdrawn from the catch rail of the runner, so that the latched engagement between the support unit and the catch rail is released.
A disadvantage of this solution is that when a plurality of support units are used, not only does the latch of the last support unit in the current direction of travel fall into the latch recess on the slideway provided for it, but in addition the latches of the support units arranged ahead of it do so as well when they pass by. Of course, the locking of those support units that have not yet reached their predefined positions is released by the support units that follow and are still in latched engagement with the catch rail. This ongoing latching and unlatching not only results in increased wear on the catches and latch recesses, but also leads to increased noise emission from the linear motion unit.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a linear motion unit in accordance with the class that is distinguished by reduced wear and noise emission.
This object is attained in accordance with the invention by a linear motion unit of the aforementioned type in which the control element has at least one control recess extending essentially orthogonal to the direction of motion, and wherein the control track includes in at least one predetermined position a control projection that can be brought into engagement with the control recess and is arranged at an angle to the direction of motion so that, when the support unit moves, the control projection moves the control element essentially perpendicular to both the direction of motion and the direction of extension of the control recess. The primary difference with respect to the above-described solution per EP 0 327 705 B1 is that the direction of motion of the control element and the direction of extension of the control recess, in other words the latch recess in the case of EP 0 327 705 B1, are not essentially parallel to one another, but rather the motion of the control element resulting from engagement with the control projection is perpendicular to the direction of extension of the control recess of the control element. The control projection thus pushes the control element to the side, which only requires a low-noise and low-wear sliding engagement between the control projection and the parts of the control element surrounding the control recess.
It must be mentioned at this point that a “motion of the control element perpendicular to the direction of extension” must be understood to include not only an orthogonal motion of the control element essentially perpendicular to both the direction of extension and to the direction of motion, but also a circumferential motion about an axis essentially parallel to the direction of motion of the runner and/or the longitudinal axis of the rod.
Accordingly, the control element can be a control disk arranged to be rotatable on the base body about an axis essentially parallel to the longitudinal axis of the rod. However, it is also possible that the control element can be a control slide that is arranged to be movable on the base body in a direction essentially orthogonal to the longitudinal axis of the rod. In both embodiments, the control element can be held by a cover element in a recess formed between the cover element and a shoulder of the base body, which facilitates a simple design option for arranging the control element on the base body.
The latched engagement between the support unit and the runner and/or the unit attached thereto can be implemented in a simple fashion if the catch has a hook element. Moreover, an additional catch can be arranged on the base body to latch an adjacent support unit. This, as well, simplifies the design of the linear motion unit, because when a number of support units are used it is not necessary for all catches for these support units to be arranged on the runner, but instead each support unit can be brought into latched engagement with its neighboring support unit. The unit mentioned above in connection with the latched engagement that is attached to the runner can thus be a support unit that is in latched engagement with the runner, or a plurality of support units that are in latched engagement with one another and with the runner.
In order to establish and release the latched engagement, the hook element can interlock with a latch surface of the control element, and there can be provided in the latch surface at least one release recess that aligns with the hook element in the corresponding release
Baker & Botts LLP
Jones Judson H.
Ramirez Nestor
Rexroth Star GmbH
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