US3355024A - Magnetic filter - Google Patents

Description

NOV. 28, 19 67 SKOYLES ET AL 3,355,024

MAGNETIC FILTER Filed Jan. 18, 1965 INVENTORJ DEREK R. SKOYLES ARTHUR .1. TYRRELL AGENT United States Patent 3,355,024 MAGNETIC FILTER Derek Robert Skoyles, East Grinstead, and Arthur James Tyrrell, Ashtead', England, assignors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Jan. 18, 1965, Ser. No. 426,137 Claims priority, application Great Britain, Feb. 3, 1964, 4,460/ 64 2 Claims. (Cl. 210-222) ABSTRACT OF THE DISCLOSURE A magnetic filter having a stack of ring magnets between a stack of annular magnets, and clamped together. The outer diameter of the discs is greater than the outer diameter of the rings. The magnets are magnetized axially and arranged so that discs alternate with rings and the adjacent discs form pole pieces of opposite polarity.

The present invention relates to a magnetic filter for filtering ferromagnetic particles from a fluid, for example oil circulating in an internal combustion engine.

In some modern motorcars the transmission oil is combined with the engine oil and there is consequently a need for a magnetic filter which is small and which may be inserted in the oil suction line without leading to a significant pressure drop. It is essential that the filter should be efficient when the oil flows is fast at maximum engine speeds since otherwise the flow of oil may cause cavitation. The filter must be efiicient at maximum flow to hold trapped ferromagnetic material against the flow of oil,

An object of the present invention is to provide an improved magnetic filter. According to the present invention a magnetic filter for removing ferromagnetic particles from a fluid comprises a plurality of spaced annular discs of soft ferromagnetic material, rings of permanent magnetic material interposed between the discs, and means for axially clamping the discs and the rings together, wherein the discs and the rings are arranged to be substantially concentrical withone another wherein the outer diameter of the rings is smaller than the outer diameter of the discs, and wherein the rings are magnetized axially in directions such that adjacent discs form magnetic poles of opposite polarity. Preferably the inner diameter of the rings is larger than the inner diameter of the discs.

The discs of soft ferromagnetic material may be provided with lugs which locate the discs and the rings of permanent magnetic material concentric with one another. Alternatively the discs and permanent magnets may be held concentric with one another by means of non-magnetic bolts which pass through apertures in the discs and which bear against the sides of the magnetic rings.

Suitably the permanent magnets may be made of a ferrite material, for example that sold under the trade name Magnadur.

In order that the invention may be readily carried into effect two embodiments thereof will now be described by way of example with reference to the accompanying diagrammatic drawings in which:

FIGURE 1 is a sectional view of a first embodiment,

FIGURE 2 is a view along the line H-II of FIG- URE 1,

Patented Nov. 28, 1967 FIGURE 3 is a sectional view of a and FIGURE 4 is a view along the line IV-IV of FIG- URE 3.

Referring now to FIGURES 1 and 2, a magnetic filter is located within a housing 1, preferably of non-magnetic material, by any suitable means, not shown. The filter comprises a number of apertured soft ferromagnetic discs 2 spaced apart by rings 3 of permanent magnetic material. The rings 3 are magnetized parallel to their axes in an alternating manner as indicated by the arrows 4. The ends of discs 2 are shaped as shown in FIGURE 2 so that a bolt 5, preferably of non-magnetic material, may serve to clamp the whole assembly together. The discs 2 are provided with lugs 6 which are bent over the rings 3 and which serve to maintain the discs and the rings in a substantially concentric arrangement.

When a fluid passes through the filter it is divided into two streams, one down the center of the discs and the rings and the other around the discs and the rings. The discs 2 act as pole pieces and magnetic fields are produced between adjacent rings, Ferromagnetic particles in the fluid are captured by these magnetic fields and become trapped in the gaps between adjacent rings 2.

The operation of the magnetic filter shown in FIG- second embodiment,

URES 3 and 4 is similar to that of the filter described with reference to FIGURES 1 and 2. In FIGURES 3 and 4 corresponding reference numerals have been used for parts corresponding to those shown in FIGURES 1 and 2. In this embodiment however the discs 2 and the rings 3 are located substantially concentric with one another by means of bolts 7, preferably of non-magnetic material, which also serve to clamp the arrangement longitudinally. Alternatively, rods or rivets may be used instead of the bolts 7.

If the filter is provided with rings and discs having equal internal diameters, a hollow sleeve, preferably of nonmagnetic material such as aluminum, may be inserted through the central bore, the ends of the sleeve being turned over to clamp the assembly longitudinally. The assembly may then be secured in the housing by means of a bolt passing through the sleeve and screwed into a suitable point on the housing. With this arrangement, the fluid will only flow along the outside of the rings and discs and not along the inside.

What is claimed is:

1. A magnetic filter for filtering ferromagnetic material from a flowing liquid comprising a plurality of spaced annular discs of soft ferromagnetic material, a plurality of rings of permanent magnetic material, each ring being interposed between spaced adjacent annular discs to form a stack, and means for axially clamping said discs and rings together, the outer diameter of each of said rings being smaller than the outer diameter of each of said discs, and wherein said rings magnetize said discs axially in directions such that each disc is of a magnetic polarity opposite the adjacent disc, each of the discs in said stack being provided with lugs projecting in opposite directions to thereby clamp said rings on either side thereof and serve to maintain the discs and rings in a substantially concentric stacked arrangement, and whereby a flow path is formed down the center of said stack and around said stack.

2. A magnetic filter as claimed in claim 1 wherein the end discs of said stack are each provided With a collar, and a non-magnetic bolt adapted to pass through said collars and to clamp said discs and rings together.

References Cited UNITED STATES PATENTS 4;, 2,705,563 4/1955 Ide 210223 2,772,778 12/1956 Furey 210-222 3,062,376 11/1962 Davis 210-222 FOREIGN PATENTS 765,495 1/1957 Great Britain.

REUBEN FRIEDMAN, Primary Examiner.

F. MEDLEY, Assistant Examiner.

Claims (1)

1. A MAGNETIC FILTER FOR FILTERING FERROMAGNETIC MATERIAL FROM A FLOWING LIQUID COMPRISING A PLURALITY OF SPACED ANNULAR DISCS OF SOFT FERROMAGNETIC MATERIAL, A PLURALITY OF RINGS OF PERMANENT MAGNETIC MATERIAL, EACH RING BEING INTERPOSED BETWEEN SPACED ADJACENT ANNULAR DISCS TO FORM A STACK, AND MEANS FOR AXIALLY CLAMPING SAID DISCS AND RINGS TOGETHER, THE OUTER DIAMETER OF EACH OF SAID RINGS BEING SMALLER THAN THE OUTER DIAMETER OF EACH OF SAID DISCS, AND WHEREIN SAID RINGS MAGNETIZE SAID DISCS AXIALLY IN DIRECTIONS SUCH THAT EACH DISC IS OF A MAGNETIC POLARITY OPPOSITE THE ADJACENT DISC, EACH OF THE DISCS IN SAID STACK BEING PROVIDED WITH LUGS PROJECTING IN OPPOSITE DIRECTIONS TO THEREBY CLAMP SAID RINGS ON EITHER SIDE THEREOF AND SERVE TO MAINTAIN THE DISCS AND RINGS IN A SUBSTANTIALLY CONCENTRIC STACKED ARRANGEMENT, AND WHEREBY A FLOW PATH IS FORMED DOWN THE CENTER OF SAID STACK AND AROUND SAID STACK.

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