Liquid purification or separation – Flow – fluid pressure or material level – responsive – Fluid pressure responsive by-pass
Patent
1995-09-26
1997-08-26
Savage, Matthew O.
Liquid purification or separation
Flow, fluid pressure or material level, responsive
Fluid pressure responsive by-pass
2104331, 210436, 210453, 2104932, 55421, 55498, 55505, B01D 3501
Patent
active
056607261
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a return filter for fluids, in particular, hydraulic fluid.
2. The Prior Art
Such return filters (DE-22 35 246 C3) have been in use for a long time for the filtration of hydraulic fluids, in particular, hydraulic oils. Disadvantages of these return filters are, firstly, that they consist of metal and their manufacture, therefore, involves considerable effort and expense, secondly, that connection lines for the returning fluid, bore holes and elaborate, threaded inserts for reception of the return line have to be provided in the filter head, and, thirdly, that the design of the ventilation holes of these filters is complicated and expensive, as such ventilation holes have an essentially circular-cylindrical connection piece arranged in the filter head which is usually closed by a cover of larger diameter than that of the connection piece, which produces between cover and connection piece an annular gap for the passage of air therethrough. The cover is held on the connection piece by a wire bracket. It can also prove disadvantageous that in return filters used in the open air, rain water, for example, or cleaning liquids or the like can penetrate through the annular gap which is open on all sides into the ventilation filter of the return filter and cause contamination of the ventilation filter or the filtered hydraulic fluid.
SUMMARY OF THE INVENTION
The object of the invention is to eliminate the aforementioned disadvantages and to create a return filter for fluids, in particular, hydraulic fluid, which can manufactured easily and at reasonable cost and which is easy to handle. In particular, the return filter should be light in weight and easy to integrate into existing liquid circuits.
The object is accomplished in a generic return filter for fluids by having a hose nipple integrally formed with the filter head to provide an inlet for returning fluid. The vent cover supports a ventilation filter. Slots formed in the lower wall of the vent housing open in the direction of the vent cover. The slots allow air to enter the vent opening with the vent cover being releasably clipped to the slots.
A particular advantage of this solution is that the filter head, the filter pot or casing and the filter cover consist of plastic. This simplifies manufacture in comparison with known return filters made of metal and reduces the manufacturing costs considerably.
It is also particularly advantageous that both the hose nipple and the housing for the ventilation hole are designed as integral parts of the filter head so that both can be manufactured together with the filter head and, therefore, no additional steps, no additional material and, consequently, also no additional costs are required for their manufacture.
From German Utility Model 87 14 819, it is known, in principle, in another filter assembly, to make the filter head, the filter pot and the filter cover of plastic. DE 30 19 141 shows in a filter, again, of a different type, a hose nipple for connecting a return line. Finally, a filter for fluids wherein a further connection is provided for connecting, for example, a manometer is described in DE 35 42 449 C1.
A filter assembly wherein connection pieces are closable by closure caps is known from U.S. Pat. No. 4,361,483.
BRIEF DESCRIPTION OF THE DRAWINGS
The following description of preferred embodiments of the invention serves to explain the invention in greater detail in conjunction with the attached drawings, in which:
FIG. 1 is a partly sectional side view of a return filter for fluids;
FIG. 2 is a partly sectional representation of a filter head taken along line 2--2 in FIG. 1;
FIG. 3 is a bottom view of a filter head; and
FIG. 4 is a sectional representation of a filter head taken along line IV--IV in FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIG. 1, a return filter 1 for fluids comprises an essentially circular-cylindrical filter head 2 with a likewise circular-cylindrical filter pot 3 arranged on one
REFERENCES:
patent: 3288291 (1966-11-01), Rosaen
patent: 4361483 (1982-11-01), Pall
ARGO GmbH fur Fluidtechnik
Savage Matthew O.
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