US2823803A - Magnetic filter - Google Patents

Description

Feb. 18, 1958 Filed Sept. 12, 1955 Fig. l

2 Sheets-Sheet 1 l7 l2 1 I Edward H. Sinclair Grover H. Curtis I4 Inventors Attorney Feb. 18, 1958 E. H. SINCI AIR ETAL 2,823,803

MAGNETIC FILTER Filed Sept. 12, 1955 2 Sheets-Sheet 2 7 2| l0 20 A 'I j i f 25 i r \\v 2| 2 24 Fig.5

Fig. 3

Edwclrd H. Sinclair Grover H. Curtis Inventors Attorney United States Patent" MAGNETIC FILTER Edward H. Sinclair, Windsor, and Grover H. Curtis, Hartland, Vt., assignors to Sinclair Machine Products, Inc., Windsor, Vt., a corporation of Vermont Application September 12, 1955, Serial No. 533,726

3 Claims. (Cl. 210-222) This invention relates to filters, and in particular to oil filters for use on machine tools, although it may be used for other purposes. Oil or other coolant coming from the cutting tols of automatic screw machines, lathes, drills, milling machines and the like carries with it a quantity of chips which it is necessary to remove before the oil is recirculated. This is ordinarily done by passing the oil through a mechanical filter having a screen or a replaceable cartridge which is cleaned or thrown away after it has become clogged. Where the metal being cut is magnetic, as iron or steel, it has been proposed to employ magnets to which the chips will adhere, but the more efiicient such a filter may be the greater will be the adherence between the chips and the magnets, causing great trouble in removing them from the magnets when it is necessary to clean the filter.

It is one object of the present invention to provide a magnetic filter in which the adherence between the magnets and the chips can be terminated at will by shortcircuiting the magnetic flux. A further object is to provide means for reversing the polarity of the magnets so that chips of hardened steel which have become permanently magnetized through their contact with the magnets will be repelled rather than attracted. A further object is to provide an oil filter which can be disassembled for cleaning without the use of tools. A further object is to provide an oil filter having no disposable element to cause expense and difiiculty in handling. Additional objects will appear from the following description and claims.

Referring to the drawings,

Fig. 1 is an exploded view of a filter constructed in accordance with our invention, partly broken away in median section;

Fig. 2 is a top view on a reduced scale;

Fig. 3 is a side view on the same scale as Fig. 2;

Fig. 4 is a top plan of the filter with the magnet poles indicated by hatching to show their relationship with the soft iron magnets which dip into the oil; the magnet poles being shown in the positions which they occupy during filtering; and

Fig. 5 is a view similar to Fig. 4 showing the magnet poles rotated so that they are short-circuited by the soft iron magnets.

The filter, in accordance with the preferred embodiment, has a body provided with a cylindrical cavity 11 in its upper surface, and a downwardly extending flange 12 interiorly threaded at 13. A bowl 14, having a flange 15 at its upper edge, fits within the cavity 16 inside the threaded flange 12, and bears against a ring packing 17. The flange 15 is pressed against the packing 17 by a gland 18 threaded at 19 to engage the threads 13, and having a hand grip 20 by which the bowl can be removed or replaced without the necessity of using tools. The bowl may be provided with threads if desired and the gland omitted.

A plurality of soft iron rods 21 are threaded or otherice wise secured to the head 10 with their upper ends flush with the bottom of the cavity 11 and their lower portions extending nearly to the bottom of the bowl 14. A cylindrical magnet 22, having a central aperture 23 and its walls cut away to form alternating pole pieces 24 and 25, is secured by a screw 26 and a spacer 27 to the interior of a cap 28 which fits rotatably over the upper portion of the body 10. When the cap is in position a pin 29 is driven through it so as to pass through a slot 30 in the upper portion of the body 10 and into a hole 31 in the permanent magnet 22. The pin is preferably filed off flush with the outer surface of the cap to prevent its unauthorized removal for the purpose of taking away the relatively expensive magnet.

The slot 30 permits a limited rotation of the cap 28 and the permanent magnet 22 relative to the rods 21, preferably enough to carry each permanent magnet pole from one soft iron rod to the next. The permanent magnet poles 24 and 25 are alternately north and south, so that this amount of rotation will reverse the polarity of the soft iron temporary magnet rods. If a hard steel chip has adhered to one of the rods it will itself become permanently magnetized, and by reversing the polarity of the temporary magnet rod it will be repelled rather than attracted and left free to drop off. Ifthe permanent magnet poles are rotated to the intermediate position of Fig. 5 they will be short-circuited through the soft iron tops of the rods and the latter will be left unmagnetized. Temporarily magnetic chips such as those of soft steel, will thus fall oil? into the bowl 14 and can be removed. Any chips still adhering to the rods can be readily wiped off with the magnet 22 in the off position of Fig. 5.

The body 10 is provided with passages 32, one at each side, connecting by short bores 33 with the cavity 16, so that as shown in Figs. 2 and 3 the filter can be connected in the oil line 34.

What we claim is:

l. A magnetic filter comprising a vessel through which the liquid to be purified passes, a plurality of soft iron rods extending into the interior of the vessel in a circular series, and a cylindrical permanent magnet having spaced poles equal in number to the number of rods and extending parallel to the axis of the cylinder into contact with one end of the series of rods, and means for mounting the permanent magnet for rotation from a position in which each pole contacts the end of one rod to a position in which each pole makes contact with two adjacent rods.

2. A magnetic filter having a body portion provided with entrance and exit ports for the liquid to be purified, a vessel detachably secured to the body portion and bridging the ports so that the liquid may flow through said vessel, a circular series or" soft iron rods passing through the body portion and extending at one end into the vessel, a cylindrical permanent magnet having spaced poles equal in number to the number of rods and extending parallel to the axis of the cylinder into contact with that end of the series of rods remote from the vessel, and means for mounting the magnet for rotation about the axis of the circular series of rods an amount equal to one-half the angular distance between adjacent rods, whereby the magnet may be located with each pole in contact with one of the rods or in a position in which each pole bridges across a pair of adjacent rods.

3. A magnetic filter having a body portion provided with entrance and exit ports for the liquid to be purified, a vessel detachably secured to the body portion and bridging the ports so that the liquid may flow through said vessel, a circular series of soft iron rods passing through the body portion and extending at one end into the vessel, a cylindrical permanent magnet having spaced poles equal in number to the number of rods and extending parallel to the axis of the cylinder into contact with that end of the series of rods remote from the vessel, and means for mounting the magnet for rotation about the axis of the circular series of rods an amount equal to the angular distance between adjacent rods, whereby the magnet may 5 be located with each pole in contact with either of two adjacent rods or in an intermediate position in which each pole bridges across a pair of adjacent rods.

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