US 3324434 A
Description (OCR text may contain errors)
June 6, 9 J. A. VASSALOTTI 3,32
ELECTROMAGNETIC RELAY WITH MAGNETIC-PLASTIC HINGE PAD Filed July 29, 1965 I 'I I L I N VEN TOR. Julia/l Yassalafii BY ATTORNEY;
United States Patent 3,324,434 ELECTRQMAGNETIC RELAY WITH MAGNETIC PLASTIC HINGE PAD John A. Vassalotti, Philadelphia, Pa., assignor to Struthers-Dnnn, Inc, Pittman, N.J., a corporation of Pennsylvania 7 Filed July 29, 1965, Ser. No. 475,818 2 (Zlaims. Cl. 335-270) ABSTRACT OF THE DISCLOSURE An electromagnetic relay has a pad of yieldable plastic material between the frame and the armature at the pivot point of the armature. The plastic pad contains finely divided magnetic particles.
This invention relates to an electrical relay capable of undergoing millions of cycles of operation without failure due to wear.
Background and summary of the invention In pivoted armature structures of the prior art, the repeated excursions of the armature has resulted in the development of wear particles which are liberated and, by migrating to the contact area, ultimately tend to cause an open contact, resulting in failure of the relay. It is an object of this invention to overcome this disadvantage and to provide a relay having longer wear.
Relays of the prior art, utilizing electromagnets and metallic frames associated with the flux path of the electromagnet, together with an armature which is reciprocable back and forth about a pivot in the flux path, have been constructed in such a Way that an air gap is introduced in the flux path. This air gap requires an increased power input to produce a given flux density, and the greater power input results in an increased generation of heat thus increasing the temperature of operation of the relay.
It is, accordingly, another object of this invention to provide a relay having an excellent flux density but which is operable at a relatively low power input and at a relatively low temperature. Other objects and advantages of this invention, including the simplicity and economy of the same, and the ease with which it may be applied to relay structures of various types, will further become apparent hereinafter and in the drawings.
Brief description of the drawing FIG. 1 represents a view in side elevation of a specific relay construction embodying features of this invention, with part of the cover shown broken away in order to reveal important internal details;
FIGS. 2, 3 and 4 are sectional views taken as indicated by the lines and arrows IIII, III-III and IV-IV respectively, which appear in FIG. 1;
FIG. 5 is a view in perspective showing the pivot portion of the armature appearing in the relay of the preceding figures;
FIG. 6 is a fragmentary view in prespective, and shown exploded, illustrating the parts that are associated with one another in connection with the pivot structure;
FIG. 7 is a view in perspective showing pivot shoulders at the corners of the armature;
FIG. 8 is an enlarged fragmentary view, shown in side elevation, of the pivot structure appearing in FIG. 1; and
FIG. 9 is an enlarged cross-sectional view of a preferred form of magnetic pad which is incorporated into the pivot structure.
3,324,434 Patented June 6, 1967 Description of the preferred embodiment Turning now to the specific form of the invention selected for illustration in the drawings, the relay shown in FIG. 1 has the usual sets of contacts 20 including spring elements 21 which normally spring-urge an operating plate 22 upwardly away from an electromagnet 23 also located within the housing 24. An armature 25 is mounted within an iron framework 26 for reciprocating rocking or pivoting movement about that frame, in a manner further to be explained hereinafter. The operating member 22 is connected to the end of the armature 25 in such manner that it moves in conjunction with the end of said armature.
Electric means including a wire 30 is provided in order, selectively, to energize and de-energize the electromagnet 23, thus alternately attracting the armature 25 downwardly toward the electromagnet, and releasing the armature for movement upwardly under the influence of the spring-urged operating member 22. In this manner, the relay is caused to open and close circuits passing through the switch contacts 20.
Having reference particularly to FIGS. 3-8 of the drawings, the structure of the pivot as shown in the drawings will be apparent. An upstanding member 35 of the frame 26 is screwed to another upstanding member 36 having an outwardly directed flange 37. The armature 25 is provided with downwardly coined corner sections 40 which contacts a water of yieldable plastic material 41, having novel features in this invention as will further be described. The armature is held in place with respect to the upstanding member 35 by a spring clip 42 extending under a tongue 43 integral with the upstanding member 36.
The wafer 41, the preferred shape of which is shown most clearly in FIG. 6 of the drawings, is preferably composed of thin vinyl plastic thoroughly impregnated with uniformly spaced finely divided particles of ferrous metal, particularly magnetic iron oxide, all as shown in FIG. 9. This wafer has been found to have and to impart to the overall structure the highly advantageous characteristics that have been referred to earlier in this specification.
It has been found that the presence of an air gap in the iron frame results in high reluctance; thus; a thin air gap provides best results but the more air gap is provided the more driving force is needed to produce the same total flux. The fact that the vinyl wear pad is filled with a multiplicity of spaced apart, finely divided particles of magnetic iron provides a reluctance factor which is approximately sixteen times lower than that of air alone. This allows the provision of a thicker vinyl gap between the metallic parts, giving better wear protection but still not greatly increasing the driving force needed to generate a given magnetic field. This is of considerable advantage since, with a given voltage and circuit, a unit having the same driving force runs at a lower temperature, and uses less power to produce the same contact actuating force.
Actually, this invention is so successful that as many as 42,000,000 cycles have been performed in mechanical life tests, and the wear was on the vinyl pad but not on the armature or on the hinge portions of the frame.
This invention is of particular advantage in connection with the wear problem, since the structure is of low load, resulting in minimum vinyl distortion, since the pivot point is approximately at the end of the armature, the spring force is approximately at the other end of the armature, and the magnetic force acts downwardly at a location intermediate the point of application of spring force and the location of the pivot.
Although this invention has been disclosed in conjunction with a specific form thereof, it will be understood that, subject to the limitations expressed above, equivalent elements may be substituted for those specifically disclosed, parts may be reversed, and certain parts may be 3 used independently of others, all without departing from the spirit and scope of this invention as defined in the appended claims.
The following is claimed:
1. A relay comprising an alternating current electromagnet, a metallic frame positioned in the flux path of said electromagnet, a metallic armature arranged across the frame and in the flux path, said armature being swingably mounted upon a supporting portion of said frame for movement back and forth in response to energization and de-energization of said electromagnet, and a piece of yieldable plastic material disposed between said frames and said armature at said supporting portion of said frame, said plastic material containing a multiplicity of spaced apart magnetic particles.
2. A relay comprising an electromagnet, a metallic frame associated with the flux path of said electromagnet, a metallic armature arranged across the frame and in the flux path, said armature being swingably mounted at a location near the end of said armature upon said frame pad of plastic material containing a multiplicity of finely divided magnetic particles disposed between said frame and said armature at said supporting portion of said frame.
References Cited UNITED STATES PATENTS 2,275,924 3/1942 Seely 335-128 2,973,464 2/1961 Wiberg 335-273 3,278,872 10/1966 Maynard 335128 X BERNARD A. GILHEANY, Primary Examiner.
G. HARRIS, JR., Assistant Examiner.