Compensating element for a pulling and pressing rod

Joints and connections – Manually releaseable latch type – Spring biased manipulator

Reexamination Certificate

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Details

C403S321000, C403S109100, C403S374100, C074S531000

Reexamination Certificate

active

06193433

ABSTRACT:

BACKGROUND OF THE INVENTION
a) Field of the Invention
The invention relates to an adjusting device for a push-pull rod, in particular to adjust length changes for the push-pull rod in continuous manner.
b) Description of Related Art
Such push-pull rods are used for instance in motor-vehicle transmissions to select and shift gears. In general a drive cable is connected to the push-pull rod and itself leads to a corresponding drive means, for instance a selecting or shifting lever or to the transmission. In order to adjust the length, for instance to compensate for tolerances, it is known with respect to such push-pull rods to adjust the rod's length in steps using a gear and mating gear and additional locking/unlocking elements. This design entails the drawback that adjustment can be carried out only stepwise, i.e., that intermediate positions are precluded. Another drawback of the known push-pull rods is the necessity to deliver them to the site of installation, for instance the assembly line of the automobile manufacturer, assembled to the drive cable. Thereby the drive cable is preset, and as a result most of the time the assembly-line worker must readjust to the precisely required length. Such a procedure frequently incurs substantial labor (unlocking the locking elements, adjusting, closing the locking elements).
SUMMARY OF THE INVENTION
It is the object of the present invention to create an adjusting device for a push-pull rod that overcomes the above cited drawbacks.
These problems are solved in the present invention by an adjusting device assembled in or at the push-pull rod and which directly or indirectly effects clamping between the push-pull rod and the adjusting-device housing or an affixation means.
The clamping, implemented in the invention by a spring, allows, when the spring is compressed, easy insertion of the push-pull rod to the desired depth and, upon releasing the spring, to reliably achieve secure positioning of the adjusting device on the push-pull rod. In this manner, the depth of insertion, i.e. the length adjustment of the cable of the push-pull rod, is reliably kept in the desired position. Using only one hand, the fitter is able to open the adjusting device of the invention, and the insertion of the push-pull rod is carried out with the other hand. In the proper setting, the desired length can be fixed in position by unlocking, by removing a securing means or by releasing the prestressed spring.
In a first embodiment, the adjusting device comprises within its housing a spring-loaded locking bush cooperating by its inside surface with a setting element affixable to the push-pull rod. In this design the locking bush clamps the setting element by spring force and as a result the setting element is irrotational. For the same reason the length of the adjusting device remains constant whether loaded tensively or compressively.
In a preferred embodiment, the inside surface of the locking bush and the cooperating outside surface of the setting element are each conical. The spring presses the conical locking bush against the conical outside surface of the setting element and in this manner reliably prevents said element from rotating. Once the setting element in turn keeps the push-pull rod in the desired position, for instance by screw-tightening, a change in the total length of the component by push or pull no longer is possible. The clamping effect between the locking bush and the setting element can be implemented by ordinary friction between two metal surfaces, by specially matched materials, by fluting, roughening and also for insance non-circular, for instance hexagonal, octagonal or other polygonal designs. It is clear furthermore that the cooperating parts also may be composed of plastic, ceramics or the like.
In a preferred embodiment, the setting element is a setting nut threaded on its inside and cooperating with a thread on the push-pull rod. The threads are made non-interlocking in order that the fitter can easily displace the push-pull rod relative to the setting nut.
In another embodiment, a helical screw is present in the housing with the push-pull rod passing through its inside. The clamping of the invention of the push-pull rod in the adjusting device takes place in that the inside diameter of the unstressed spring is less than the outside diameter of the push-pull rod, or in that the spring forces an element located between it and the push-pull rod on latter. The spring is bent for instance by rotation about its own axis to allow insertion of the push-pull rod. Thereby the spring enlarges its inside diameter and permits inserting the push-pull rod. When the spring is released, it again reduces its diameter and clamps the push-pull rod in position.
Besides the clamping effect of the helical spring, the adjusting device also may comprise one or more clamping elements fitted with ride-on bevels or rest surfaces facing the helical spring.
In a preferred embodiment the push-pull rod is held in place directly by the spring having the smaller inside diameter. If the rod is tensively or compressively loaded, then the spring will be pressed against the ride-on bevels of the clamping elements and as a result the particular spring coil diameter is further reduced In this manner the clamping effect of the adjusting device of the invention is increased even further.
A setting piece may be provided to more easily spread apart the spring, said piece being rigidly joined to the spring or to its ends and extending outward. The fitter is able to easily rotate the setting piece relative to the housing, for instance using the thumb of his hand holding said housing, and then he may insert the push-pull rod to the appropriate length. After the end of the setting procedure, the spring encloses or compresses the push-pull rod which it retains in this intended position and thereby the full drive element is kept at the desired length.
In a further embodiment, spring-loaded clamping elements are present in the housing and comprise conical surfaces (for instance outer surfaces) cooperating in such manner with one or two opposite, for instance inwardly conical, seats in such manner that the push-pull rod inserted in it is clamped in place directly or indirectly. In this design the spring presses conical elements into conical mating surfaces and illustratively a radial clamping force is then exerted by diameter reduction, leading to reliable affixation of the push-pull rod. The adjusting device of the invention may comprise a conical clamping element forced by a spring into a recess, or two clamping elements may be present which are forced by the spring into opposite directions and thereby into two mutually opposite conical recesses. This design offers reliable positional affixation for both tensile and compressive load. Illustratively the clamping elements may comprise a slot to reduce their diameter when being clamped and thereby exerting compression on the push-pull rod, or they may transfer the clamping effect directly or indirectly to the push-pull rod.
The indirect transmission takes place for instance using rollers or balls forced during shifting by the conical recesses against the push-pull rod and thereby automatically increasing clamping.
A securing means may be provided for easy assembly to keep the spring generating the compression in the compressed state in the unassembled state, whereby the clamping elements do not cooperate with the recesses and consequently the push-pull rod can be easily inserted. Once the push-pull rod has been moved into the desired position, the fitter need do no more than remove the securing means. As a result the spring is released and forces the clamping elements against the seats, achieving reliable setting of the push-pull rod to the desired length. The securing means may be in the form of a disposable splint discarded following assembly, or it may be an operating element remaining at the adjusting device to allow easy access to the spring for subsequent readjustments in order to compress said spring and render the push-

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