Fluid handling – With cleaner – lubrication added to fluid or liquid sealing... – Cleaning or steam sterilizing
Reexamination Certificate
1999-10-29
2001-10-23
Walton, George L. (Department: 3753)
Fluid handling
With cleaner, lubrication added to fluid or liquid sealing...
Cleaning or steam sterilizing
C073S29000R, C137S386000, C137S392000, C137S558000, C222S064000
Reexamination Certificate
active
06305404
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a device for checking the contents of a container for a non-self-leveling supply substance, such as lubricant, grease or the like. The container includes a stirring blade that is movable about an axis of rotation for delivering the supply substance to a consuming receiver, for example the suction chamber of a lubrication pump, and for freeing the supply substance of air inclusions. If appropriate the container is provided with an associated scraper for scraping the supply substance from the container wall and from the stirring blade. The container is also provided with a measuring unit for measuring the level of the supply substance contained therein.
In checking, in particular of low level monitoring, of the contents of containers for highly viscous supply substances, such as lubricant, grease or the like, such as for example are used in connection with central lubricating pumps, problems arise due to the high rigidity of the supply substances since it no longer behaves in a self-leveling manner. This applies inter alia in particular to greases starting at Class 2 of the consistency classification of the National Lubricating Grease Institute (NLGI) or DIN 51 818. In the case of a supply of these substances, it cannot be readily assumed that a flat surface is present in the container which could serve for measuring the level of fill.
Conventionally a rotating stirring blade is used to free the supply substance of air inclusions and supply the substance to the suction chamber of the receiving device. On the surface of the supply substance, peak and valley-like formations are generated because the rotational movement of the stirring blade always pushes the supply substance ahead of itself. The formation of the peaks and valleys, under some circumstances, may even be augmented through the measures for scraping off the supply substance from the stirring blade. The conditions are similar in the case of a rotating scraper for scraping the supply substance from the container wall. Therefore, the use of measuring units, which are known per se, and rely on the principle of reflection, is not possible. Solutions of this problem by use of a follower plate disposed on the surface of the supply substance for the purpose of leveling it, have the disadvantage that a portion of the useful contents is lost. Furthermore, with such a level-smoothing solutions, the expenditures in terms of construction and the other costs generated thereby are relatively high.
DE 44 33 170 A1 discloses a unit for monitoring low levels in a lubrication supply container. The unit comprises a stirring blade with a holder, pivotably articulated thereon for a position transmitter. The principle of monitoring in this unit is that, by means of a position sensor, the position of the position transmitter is acquired depending on whether or not a direct mechanical reciprocal interaction exists between the position transmitter and the supply substance.
SUMMARY OF THE INVENTION
The object of the present invention is to create an improved device of the above described type, wherein a contents check with a measuring unit is possible, which presupposes a smooth surface, such as is the case with self-leveling supply substances.
This object is achieved according to the present invention through providing at least one radial stationary flank member in the region of the container bottom, which has a plurality of openings for the transfer of the supply substance in the direction toward the receiver. The at least one radial stationary flank member is spaced apart from the container bottom at least in the region of the container center such that a stirring blade can be rotated, at least partially, under the stationary flank, i.e. under a portion of its length.
The configuration of the stationary flank, stirring blade and scraper permit the smoothing of the surface of the supply substance such that a reliable measurement of the level of the surface of the supply-substance in the container can take place even if the supply substance has a high rigidity or viscosity and is not self-leveling. Thus, the build-up of peak and valley formations on the surface of the supply substance is effectively prevented.
In preferred embodiments of the present invention the measuring unit comprises a signal transmitter/sensor combination, for example for sound or light signals, in particular in the upper container region in the center of the container, with signal emission taking place preferably symmetrically with respect to the rotational axis of the stirring blade. This avoids, or at least reduces, error reflections which could be caused by the scraping means of the stirring blade as well as errors caused by the absence of reflections which, are the result of a funnel formation in the container center during the emptying of a full container. Also avoided are errors caused by a level increase in the container center when filling the container from below.
If the signal transmitter/sensor combination is disposed on a preferably detachable container cover comprising, if appropriate, a signal opening, an especially simple mounting of the signal transmitter/sensor combination with ready accessibility of the interior of the container is ensured.
In order to decrease the danger of contamination of the signal transmitter/sensor combination, it is disposed so as to be recessed in a cavity of the measuring unit with the cavity being aligned with the signal opening.
An especially simple and functionally reliable structure of the device according to the present invention is attained if the axis of rotation of the stirring blade is disposed in parallel, preferably coaxially, with respect to the center axis of the container.
In a device according to the present invention, the stationary flank comprises a fastening part disposed in a peripheral region in the container as well as a resistance part extending tongue-like in the direction of the container center. The parts are matched to the shape of the stirring blade.
In a further preferred embodiment the particular radial stationary flank is implemented as a right-angled profile with upper surfaces and lower surfaces extending in parallel to the container bottom, which offers special efficiency as a scraping means.
A secure and simple fastening of the particular stationary flank in the container is attained so that the fastening part is detachably or nondetachably secured on the container bottom and/or on to the container wall.
A further improved smoothing of the supply substance surface is achieved by providing two or more stationary flanks that are disposed symmetrically with respect to the axis of rotation of the stirring blade. In the case of two stationary flanks, the flanks are offset, preferably by 180°, with respect to one another.
An even further improvement of the smoothing of the supply substance surface is attained by providing the scraping means with vertical and horizontal strap segments that are matched to the particular stationary flank and, if appropriate, to the container wall.
Increased functional reliability is additionally achieved by providing the measuring unit with a control and evaluation module with which a time-averaged value formation can take place over a number of discrete measurements. If the device is operated in such a manner, the effect of error measurements, due to an incomplete planar supply substance surface, can be corrected.
The signal sensors comprise a switching hysteresis in order to prevent the output signal from switching on and off about the switching point.
In order to achieve a supply substance surface of the greatest possible planarity even when the container is being filled and emptied, a plurality of openings are provided in the container bottom for filling and emptying.
Further goals, characteristics, advantages and application possibilities of the present invention will be evident based on the following description of exemplary embodiments in conjunction with the drawing. Therein all described and/or graphi
Lincoln GmbH
Walton George L.
Wenderoth , Lind & Ponack, L.L.P.
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