Registers – Package operated – Package operated switch
Patent
1996-03-29
1997-10-28
Gellner, Michael L.
Registers
Package operated
Package operated switch
235 98B, B61L 116, G06M 700
Patent
active
056820259
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to load alternation counting device of an actuation device which is periodically pressure loaded, especially of a hydraulically operated screw driving cylinder. Screw driving cylinders have the function to deliver an exactly preset preclamping force onto a screw bolt in order to be able to fasten or release a nut screwed onto the screw bolt. For this purpose, the screw driving cylinder is threaded onto the thread projecting above a nut and subsequently the screw driving cylinder is loaded with hydraulic pressure. This has the consequence that the screw bolt is tensioned by lengthening. The forces applied to the screw bolt are extremely high so that the screw driving cylinder and its individual parts are subjected to a great load. In order to prevent that these highly loaded individual parts break during tensioning of the screw bolt, because, due to surpassing the number of load alternation permissible for these parts, fatigue fracture occurs, it is desired to exchange individual parts that are at risk for fatigue fracture before such fatigue fracture occurs. This is also true for the timely exchange of other parts subjected to wear, for example, gaskets.
In German published document 35 12 568 a stroke counter for reciprocating parts such as piston rods, press rams etc. is disclosed which comprises a sensor arrangement that senses the moved parts passing it. The sensor arrangement is comprised of two sensors spaced apart in the direction of movement which are both positioned within the stroke length. They cooperate with an evaluation circuit connected thereto which operates such that it allows passage of the initial signal of one of the sensors for counting the strokes but only when the initial signal of the other sensor has been received before.
This arrangement serves to provide a reliable counting of strokes even when the strokes due to variations of the operational conditions of the reciprocating part fluctuate, for example, due to changing frictional conditions or differently sized loads which are driven by the part. For this purpose, the two sensors of the sensor arrangement are arranged at a distance from the two stroke length ends in a range of a working stroke which will be definitely passed even when fluctuations of the operational conditions are present. In this manner no stroke will be lost for counting. Since this known stroke counter does not detect load conditions, but is exclusively designed to count strokes even though the stroke length may vary, strokes without load are also counted with this known stroke counter which, with respect to monitoring fatigue fractures or wear of gaskets, are meaning less. For this reason, the known stroke counter is not very suitable for load alternation counting devices of actuating devices of the aforementioned kind because with this stroke counter more strokes than necessary are counted for monitoring exchanging of highly loaded individual parts in order to prevent fatigue fracture so that when using the known stroke counter an exchange of these parts will be preformed unnecessarily prematurely.
The invention has the object to provide a load alternation counting device which counts only the load conditions which are relevant for exchanging parts that are at risk for fatigue fracture in order to have the possibility to exchange after a preset number of load alternations certain highly loaded parts.
Based on this object, a load alternation counting device is suggested that inventively comprises a cylinder connected to the pressure source of the actuating device for pressure loading, a piston arranged sealingly and displaceably within the cylinder, and a counter which is switched by the axial piston movement. The counter is coupled with the piston by a mechanism which transfers the linear movement of the piston into timed rotational movement of the counter via a spring element that is designed according to the piston diameter and the hydraulic pressure.
The load alternation counting device for an actuation dev
REFERENCES:
patent: 3186311 (1965-06-01), Carlson
patent: 3703629 (1972-11-01), Hanbicki
patent: 3843047 (1974-10-01), Otsuka et al.
patent: 4041282 (1977-08-01), Uchida et al.
patent: 4322966 (1982-04-01), Golabek
patent: 4993259 (1991-02-01), LaFountain
patent: 5538256 (1996-07-01), Rinne
Hohmann Frank
Hohmann Jorg
Chapik Daniel
Gellner Michael L.
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