IL132556A - Filter - Google Patents

Abstract

A filter (10) for liquids contaminated with waste particles comprising a generally cylindrical axisymmetric filter body (12) defining a main axis and having an axial inlet (14) and a lateral outlet (16), a coaxial torpedo- like body (20) extending inside and along said filter body and occupying most of its internal volume, said torpedo-like body having a head part (22) of generally axisymmteric shape disposed against and converging towards the axial inlet, and a cylinder part smoothly merging with the head part and extending axially away from said head part, said head part and the filter body defining an annular passage therebetween, a filtering screen (26) of a cylindrical shape positioned inside the filter body coaxially with and around the torpedo-like body, to form an annular gap (28) therebetween and to cross the flowpath towards said lateral outlet; characterized in that an annular array of swirling vanes (34) is placed coaxially at the downstream end of the head part in said annular passage to impart to the flow in said annular gap rotational velocity about the main axis of the filter. 1157 י" ב בסיון התשס" ב - May 23, 2002

Description

Filter Amiad Filtration Systems (1997) Ltd.

C. 118540.4 A FILTER WITH SWIRLING VANES FIELD OF THE INVENTION This invention relates to filters, and more specifically to filters using swirling motion of the filtered liquid.

BACKGROUND OF THE INVENTION Filtering devices for separation of waste particles from liquids have wide use in irrigation systems, fuel and oil feeding systems, etc. Since the contaminant particles usually have specific gravity different from that of the liquid, it is advantageous to use forces of inertia and gravitation for their separation.

US 5,076,942 to Goodman et al. describes a filter with a hollow housing accommodating a cylindrical filtering element and a torpedo-shaped volume reduction device (hereinafter "torpedo") placed in the filtering element and occupying a major portion of the housing volume. The particle-laden liquid passes and accelerates through a narrow annular gap formed between the torpedo head and the housing. The forces of inertia acting on the curved flow contribute to the separation of solid particles from the liquid.

US 5,466,384 to Prevost et al. describes a series of filters wherein the contaminated liquid is passed along a helical path by means of a stationary Archimedes screw placed inside or outside a cylindrical or conical filtering element. The filtrate liquid passes through the filtering element, while contaminating particles are let out with a small portion of the liquid.

SUMMARY OF THE INVENTION In accordance with the present invention it is provided a filter for liquids contaminated with waste particles using the effects of accelerated curvilinear flow both in the annular passage along the head of a torpedo-like body, and in the annular cylindrical gap formed along the rest of the body.

The filter comprises a generally cylindrical axisymmetric filter body defining a main axis and having an axial inlet and a lateral outlet, and an internal volume-reduction axisymmetric torpedo-like body occupying most of the filter body internal volume. The torpedo has a head part of generally ellipsoid or ogive axisymmetric shape disposed against and converging towards the axial inlet, the head part smoothly transiting into a right-cylinder part extending along the axis of the filter body. The filter has a filtering screen of cylindrical shape positioned coaxially around the torpedo-like body, inside the filter body and across the flowpath from the inlet to the outlet, and is characterized in that a circular array of swirling vanes is placed coaxially in the flowpath at the downstream end of the head part to impart to the flow rotational velocity about the main axis of the filter. The relatively short swirling vanes are positioned on the widest part of the head, just upstream of the cylinder part of the torpedo-like body so as not to enlarge the overall diameter of the filtering element, and to create least hydrodynamic drag.

The filter body, the cylinder part of the torpedo and the filtering screen extend axially beyond the lateral outlet and form an annular settling chamber for the waste particles. The filter is therefore adapted to operate with the inlet in upward position and the settling chamber in downward position. A set of draining openings connects the settling chamber with the torpedo interior, and the filter is provided with a drain valve adapted to flush the liquid from the interior into the ambient atmosphere.

The filter of the present invention uses, firstly, the curvilinear meridian flow along the torpedo head and, secondly, the curvilinear helical flow about the cylindrical part of the torpedo for better separation of waste particles from the liquid and is effective in a wide range of flow velocities. The swirling vanes causing the helical motion of the flow are relatively short and more hyrdodynamically effective than an all-length Archimedes screw known in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Fig. 1 is a section elevation of a filter with torpedo and swirling vanes according to the present invention.

Fig. 2 is a cross-sectional view of the filter of Fig. 1 in the plane 2-2.

DETAILED DESCRD7TION OF THE INVENTION Fig. 1 shows a sectional view of a liquid filter 10 for separating solid waste particles from a contaminated liquid. The filter has a generally cylindrical body 12 with top axial inlet opening 14, mid-height lateral outlet opening 16 and bottom drain valve 18. A great portion of the internal volume of the filter body 12 is occupied by a coaxial hollow torpedo-like body 20 (hereinafter "torpedo") comprising a streamlined head 22 having an upstream portion located against and converging towards the inlet opening 14, and a downstream portion smoothly transiting into a cylindrical part 24. The upstream portion of the head 22 forms an annular liquid passage 25 with the filter body 10. A cylindrical filtering screen 26 is disposed around the torpedo defining a second annular liquid passage 27 with the downstream portion of the head 22, and an annular gap 28 with the cylindrical part 24 of the torpedo. A set of swirl-generating skewed vanes 34 encircle the downstream end of the torpedo head 22, occupying the second passage 27 before the entrance of the gap 28. The lower part of the gap 28 constitutes a settling chamber 36. A few peripheral draining openings 38 disposed at the bottom end of the torpedo enable the liquid to flow from the settling chamber 36 into the internal space 40 of the torpedo and the drain valve 18.

The contaminated liquid entering the filter body 12 through the inlet opening 14 accelerates in the annular passage 25 in a generally meridian curvilinear flow along the torpedo head 22. At the end of the head, the liquid flows between skewed vanes 34 and swirls in the annular gap 28 between the cylindrical part 24 of the torpedo 20 and the screen 26. Due to the centrifugal forces, the waste particles with specific gravity greater than water slide close to the screen 26. Particles with specific gravity less than water slide along the torpedo surface and penetrate the internal volume 40 of the torpedo through openings 38. Upon opening of the drain valve 18, all waste matter accumulated in the internal volume 40 of the torpedo 20 is discharged out of the filter. The liquid relieved of contaminating particles passes through the screen 26 and exits through the lateral outlet opening 16.

While there has been shown one embodiment of a filter with torpedo and vanes in accordance with the invention, it is to be understood that many changes may be made therein without departing from the essential spirit of the invention.

Claims (5)

CLAJDMS:

1. A filter for liquids contaminated with waste particles comprising a generally cylindrical axisymmetric filter body defining a main axis and having an axial inlet and a lateral outlet, a coaxial torpedo-like body extending inside and along said filter body and occupying most of its internal volume, said torpedo-like body having a head part of generally axisymmetric shape disposed against and converging towards the axial inlet, and a cylinder part smoothly merging with the head part and extending axially away from said head part, said head part and the filter body defining an annular passage therebetween, a filtering screen of a cylindrical shape positioned inside the filter body coaxially with and around the torpedo-like body, to form an annular gap therebetween and to cross the flowpath towards said lateral outlet; characterized in that an annular array of swirling vanes is placed coaxially at the downstream end of the head part in said annular passage to impart to the flow in said annular gap rotational velocity about the main axis of the filter.

2. A filter according to Claim 1, wherein the upstream end of said filtering screen overlies the downstream end of the head part defining a second annular passage therebetween and the array of swirling vanes occupies said second annular passage.

3. A filter according to Claim 1, operating with the axial inlet in upward direction and with the lateral outlet spaced from said inlet by about a half of the height of the torpedo-like body, wherein the filter body, the right-cylinder part of the torpedo-like body and the filtering screen extend axially down beyond the lateral outlet and form an annular settling chamber for the contaminating particles.

4. A filter according to Claim 3, wherein the torpedo-like body has an internal cavity and draining openings between said cavity and said settling chamber, and the filter body is provided with a drain valve adapted to flush the liquid from said cavity into the ambient atmosphere.

5. A filter according to any one of Claims 1 to 4, wherein the filter body has the shape of two frustum cones joined by their larger bases. For the Applicants