US2589766A - Magnetic oil seal construction - Google Patents

Description

NOW BY JUDICIAL CHANGE OF NAME WlLB N F. BRADLEY MAGNETIC SEAL CONSTRUCTION Filqd May 4. 1945 l l I//JV//I//A i t 7 9 @l INVENTOR.

. Y WILBURN F. BAERNSTEIN,NOW 'BY JUDICIAL CHANGE NAME,W|LBURN F. BRADLEY Patented Mar. 18, 1952 MAGNETIC OIL SEAL CONSTRUCTION Wilburn F. Bernstein, Hollywood, Ill., now by judicial change of name Wilburn F. Bradley; f Evelyn Bradley administratrix of said Wilburn F. Bradley, deceased Application May 4, 1945, Serial No. 591,980

- 2 Claims.

1 The present invention relates generally to improvements in permanent magnetic materials, and has 'reference particularly to a new and improved oil seal comprising a flexible composition of matter having a high degree of magnetic retentivity. v

Permanent artificial magnets are `commonly made of solid materials, such for example as hard steel or steel alloys, and are provided in a large variety of forms to serve different useful purposes. However, because of their rigidity of form and other limiting physical characteristics, these materials have restricted the use of magnets primarily to electrical devices and appliances, and have necessitated comparatively expensive methods of manufacture to produce magnets of the desired form for each individual purpose.

An object of the present invention is to provide a new and improved oil sea1 comprising a flexible lip incorporating a magnet or magnetized material capable of exerting a tractive eiort. and operable by reason of its capacity of flexure or deformation in response to magnetic stress to y maintain close bearing contact with a relatively movable part Vof magnetic material, i. e., a material subject to magnetic attraction.

A further and more general object is to provide a new and improved flexible magnet or magnetized material which is adapted for use in a seal construction and which is simple and inex pensive to produce either in large stock lots for subsequent fabrication, or in special molded or formed shapes, and which is readily deformable under magnetic stress to conform closely and intimately to the surface of a contacting member of magnetic material.

Other objects and advantages will become apparent as the description proceeds.

In the accompanying drawing, L

Figure l is a fragmentary longitudinal sectional view on an enlarged scale through a yieldable bar magnet embodying the features of the present invention. y Fig.' 2 is a diagrammatic view of the bar magnet illustrating the orientation of the magnetic axes of the internal elementary magnets.`

Fig. 3 is a fragmentary axial sectional view of an oi1 seal packing illustrating one use of the yieldable permanent magnet.

The ilexible magnet or magnetic material, which is contemplated by the present invention, in general comprises a body or matrix I of any suitable flexible or resilient base stock deformable in response' to magnetic stress, and any suitable magnetic material having a high degree of magnetic retentivity and being divided into particles 2 embedded in and interspersed through the matrix.

The base stock, which serves as the bonding medium for the magnetic particles and defines the external form of the magnet, Vis flexible and preferably resilient in character, and mayconrubber composition or other rubber-like material. Included in the class of materials that may be used are, by way of illustration but not limitation, Buna N, Buna S, butyl rubber, a product known in the trade as Neoprene and comprising polymerized chloroprene, and another product known in the trade as 'I'hiokol and comprising organic polysulphide. The rubber-like material may be compounded with various other ingredients, as is customary in the rubber art, affecting vulcanization, plasticity, tensile strength, weight and resistance to abrasion, etc., and in general to obtain themost desirable characteristics for a particular intended use. As one typical illustration, the base stock may comprise a suitably treated composition of the following 'ingredients in the following proportions by weight:

Parts Buna N 100 Carbon black 20 A softener, such as coumarone indene resin 10 Zinc oxide 5 An anti-oxidant, such as phenol beta naphthalene 2 Sulphur 1 An accelerator, such as di-butyl amine 0.5

The magnetic particles 2, which are bonded in the base stock l, may comprise any suitable material which can be permanently magnetized by induction upon being introduced into a proper magnetic field. Thus, the particles 2 may consist of crushed or comminuted iron, steel or any one of various ferrous alloys, such for example as a number of aluminum-nickel-iron alloys ,known in the trade as Alnico,,Alnic and Nipermag."

A'Although the magnetic material 2 should be finely divided, and preferably is used in pulver- Y ant form, the degree of neness is not closely critical. It is desirable, however, that the particles 2 be as small as practicable so as to permitw of close and Substantially uniform interspersion thereof, and to obtain greater continuity of the ch a'ra'cteristics that are desired in the resultant product. In general, as the amount of the magnetic material 2 in the composition is increased.

` the resultant product experiences a correspond- -ing increase in magnetic strength and decrease in.; flexibility or resiliency.

If a comparatively stiff'magnet 'is desired, themagnetic material 2 sist for example of natura-l or synthetic rubber,

may be added to the mixture in amounts up to by weight as maximum limit With'satis- ,processing of rubber.

is crushed or comminuted to the desired degree.V

,Y 3 factory results. If. this. limit is exceeded, the magnet will be too rigid for many purposes, and

Where a strong magnetic flux is unnecessary, and a high degree of flexibility is desired, the magnetic material may be added to the mixture in amounts down to as a mim'mum limit. The optimum proportions for most purposes comprise by Weight approximately '75% of the divided magnetic material and of the rubber or rubber-like bonding material.

The permanent magnet or magnetic material may be advantageously made by a method which comprisesprocessing the flexible resilient nonmagnetic bonding material asis well understoodv in the art. Thus, the main or base ingredientv is` compounded in suitable conventional equip-I mentwith other modifying substances. inthe same manner as is commonly employed, in the.

The magnetic material 2 Y Will lack physical strength. On the other hand,

of fineness, and is then added in the. desiredl y particles substantially uniformly throughout'theA bonding. material' I. After the mixing operation, the composition may be further processed in the same manner as if the magnetic particles were not present to. cure the `bonding material, and to produce the resultant or finished product in the desired form. 'I'he resultant product is now permanently magnetizedv in any suitable manner,

as for example by introduction into a strongl magnetic eld until permanent magnetization of the magnetic'particles 2 isY effected'. According to'the molecular theory, the elementary' magnet elements are thereupon arranged with their' magnetic. 'axes parallel to the direction-of niag-y netization as illustrated in Fig. 2, thus establish ing north` and south poles N and S. at opposite ends of the bar. It will be understood that the direction of polarity 'mayl be controlled by dis-- position of the magnet within the magnetizing iield.

The magnetized material, in the course of pro-L duction, may be molded or otherwise shaped inv stock lengths' to be' subsequently cut or fabricatedsinto` individual magnets of any desired form, or alternatively may be initially shaped in-4 Vto the desired form of the finished magnets.

The material. being readily severable by a knife, can be quickly and economically shaped into variousA complex magnet forms.

comprises. an outer shell 4 mounted within a counterbore 5 in a housing lIi through which the shaft extends. The shell 4 comprises a side wal] 'i and a peripheral wall 8 in which a packing 9 in the form of a U-shaped resilient diaphragm is inserted. A retaining Washer I0 is secured against the outer leg`of the diaphragm 9. The inner leg of. the diaphragm constitutes a yieldable sealing lip I I which is flexed outwardly to engage the surface of the shaft 3 With deformation pressure. Molded within the sealing lip II is a flexible magnet I2 embodying the present invention. Due to the magnetic attraction between the Vshaft. .3 and the magnet. I I, the sealing lip II is held closely against the shaft to provide a fluid-l:v tight seal regardless of `,rubber fatigue and withoutfrequiring the use of any additional pressure element, such as the commonly-employed garter spring (not shown).- 'Ihe sealing pressure created by the magnet I2I is uniform throughout the pe-V riphery of the shaft 3, and not subject to impair.-`

ment. Y

I claim as my invention:

l. An oil-seal fora rotating shaft comprising, in` combination, a yieldable. packing having an annular sealing lip of rubber-like material adapted for engagement under iiexure with the.

periphery of said shaft, comminuted particles of permanently magnetized material embedded in said lip and interspersed therein, said particles being arranged to define in said lip points of free opposite polarity producing external` magnetic flux to maintain said lip in sealing contact with said shaft. Y

2., An, oil seal for a rotating shaft comprising,A

in combination, a, yieldable packing, having an ,annular sealing lip of rubber-like material adapted for circumferential engagement. Vunder flexure. with theperipheral surface of saidshaft, and an annular permanent magnet molded With-.- in said. lip and, fully enclosed therein in position l toV encircle said shaft, said magnet comprising a matrix.

Magnets of the present invention, because of their fiexibility or resiliency, will deform or vflex through an air gap under magnetic stress to con-` form to and maintain close contact with a con-4 tiguous surfaceof magnetic attractive material. Thus, Vthe Vfiexible magnet is especially advan tageous in oil seals for maintaining close contact of the sealing member With .a relatively movable element such as a rotating shaft. One form of oil, seal, utilizing a iiexible magnet embodying the present invention, is shown in Fig. 3. Except, for the `use vof the magnet, this oil seal is of conventional construction.

The cil seal is for a revolving steel shaft 3, and" matrix of rubber-like resilient material and a; quantity of finely divided permanently mag,-A netized material of high magneticV retentivity molded with and disbursedv throughout said VILBURN. F, BERNSTEIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,790,704 Harris Y Feb1 3, 1931 1,872,182 Pohl Aug. 16,.-1932V 1,889,380 Ruben Nov. 29, 1932, 1,940,228 Polydoiol Dec. 19, 1933 1 994,534. RobinsonV Mar. 19, 1935 2,062,938 Ruppe Dec. 1, 1936 2,188,091 Baermann, Jr Jan. 23, 1940 2,199,525 McCoWen, May '7,y 1940 2,205,611 Wassermann June 25, 1940 2,254,933 Bryce Sept. 2, 1941 2,283,925 Harvey e May 26, 1942 2,289,607 Victor July 1.4 1942 2,318,415 Patzschke et al. May 4, 1943 2,391,553 Goldberg V Dec. 25, 1,945

FOREIGN PATENTS Number l, Country p Date 333,154 Great Britain Aug. 5, V19.30 155,805'- .l Great Britain O Ct. 28, V1936' 538,226"v4 'Great Britain July 25, 1951112

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