US 2990465 A
Description (OCR text may contain errors)
J 1961 w. E. DUMKE ET AL 2,990,465
' SWITCH STACK ASSEMBLY Filed March 30, 1959 FIGB JAMES R. BAILEY WILLIAM E. DUMKE INVENTORS U wam P fi I 2,990,465 7 I SWITCH STACK ASSEMBLY William E. Dumke and James R. Bailey, Chicago, Ill.,
assignors to Switchcraft, Inc, Chicago, 111., a corporation of Illinois Filed Mar. 30, 1959, Ser. No. 802,743 3 Claims. (Cl. 200-166) This invention relates to the assembly of switches of theftype where the switching elements are arranged alternately with insulating wafers therebetween.
For convenience, an item of the class described may be made as a partly completed assembly and may consist of such alternately arranged switching and insulating elements held inan assembly to insulating tubing or sleeves. Such partly completed assembly can later be attached by mounting screws or rivets to any permanent fixture.
One of the problems attendant upon fabrication and storage of such assemblies has been that of the insulating spacers.- By reason of their organic compositions their dimensions change with time, and a snugly assembled stack becomes loose, the component parts sometimes being disassembled. In those cases where the assembly has a certain degree of looseness initially, the assembly becomes more loose withthe passage of time.
The invention herein overcomes the difiiculties in maintaining the switch stacks in assembled relationship, and in a manner appreciably I lessening the manufacturing costs.
According .to. the. present invention, the insulating sleeves and spacers are so related as to have an interfe'renc'e fit." mime 'prior'art it'was entirely possible to have an insulating sleeve having an interference fit with the spacer, the difference in the diameter of each causing the interference. Where, for example the CD. of the sleeve was .001" greater than the ID. of the spacer, the interference was not excessive provided the sleeve was not of too great a length, but where a relatively high stack was assembled, the pressure to complete stacking could in some cases cause crushing of the insulating sleeve.
In practicing the invention herein, the spacers have openings with major and minor diameters, these being so as to provide deformable portions in interference engagement with the insulating sleeve. There thus is provided on the sleeve, one or more such deformable portions having such interference fit, and these deformable portions may be spaced equiangularly on the spacer, or otherwise as desired.
The insulating sleeves are related so that the deformation takes place only on the insulating spacer, and all interference takes place between the minor diameter portions and the major diameter portions thereof. The sleeve is accordingly made so that its CD. is greater than the minimum ID. of the spacer and not greater than the maximum ID. of the spacer.
With the foregoing considerations in mind it is a principal object of the invention to construct a switch assembly in assembled condition for purposes of handling and shipping without the need for accessories to maintain the assembled relationship which would add to the manufacturing costs.
A further object is the provision of means for maintaining a switch assembly in condition for handling and the like, said means including the provision of insulating wafers or separators cooperating with insulating sleeves, said insulating wafers being specifically configured to maintain the assembled relationship and to prevent the components from becoming disassembled prior to a permanent installation.
Other objects and important features of the invention will become apparent from a study of the specification taken with the drawing which together describe and illustrate a number of preferred embodiments of the invention and what are now considered to be the best modes of practicing the principles thereof. Other embodiments may be suggested to those having the benefit of the teachings herein, and such other embodiments are intended to be reserved especially as they fall within the scope and purview of the subjoined claims.
In the drawing:
FIG. 1 is a perspective view of one form of an insulating spacer adapted for use with an improved switch assembly according to the present invention;
FIG. 2 is a plan view thereof;
'FIG. 3 is a section taken along the 'line 33 of FIG. 2 looking in the direction of the arrows;
FIG. 4 is a perspective view of a partly assembled switch stack showing themanner in which the improved insulating spacer is assembled thereto;
FIG. 5 is a section taken along the line 5-5 of FIG. 4 looking in the direction of the arrows;
FIG. 6 is a section similar to FIG. 5, and showing how the switch stack assembly can be permanently secured in place;
FIG. 7 .is a plan view of an insulating spacer according to another embodiment of the invention; and
FIG. 8 is a section taken along the line 8--8 of FIG. 7 looking in the direction of the arrows.
Referring now particularly to FIG. 1 of the drawings, an improved insulating spacer is referred to generally by the reference numeral 10 and comprises a wafer 11 made of insulating material and having a plurality of spaced punchedv out openings. 12 therein. As seen in FIG. 2,
each of these openings 12' has a principal or major diameter d corresponding to the outside diameter of an insulating sleeve 13 seen in FIGS. 4 and 5.
As seen in FIG. 2, each of the openings 12 is formed with chordal portions 0, each of the chordal portions 0 being tangent to a circle of smaller diameter a In the desired case the difference between the two diameters d and d should afford an interference fit between the spacer and the insulating sleeve, the difference in the diameters being varied according to the diameter of the sleeve, the material of the sleeve and the spacer, and the thickness of the spacer. Each of the chordal portions c may preferably be disposed equiangularly apart so that the spacers will be properly centered on the sleeve 13.
Referring now to FIG. 4, each of the insulating spacers 11 alternates with a switch element indicated generally by the reference numeral 14. As seen also in FIG. 4, a pair or more of such spacer elements 11 may separate a pair of switch elements 14. In assembling the elements into a switch stack, the sleeves 13 are placed in position as seen in FIGS. 4 and 5 into the opening 12 in the insulating spacer 11. The various components making up the assembly, i.e., the insulating spacers 11 and the switch elements 14 are stacked as seen in FIGS. 4 and 5. In so doing, each of the insulating spacers 11 is in an interfering fit with the sleeve 13, and is distorted a slight amount at its chordal surface as indicated at 0 in FIG. 5. This distortion enables the spacers 11 to grip the insulating sleeve 13 very tightly. All of the elements may be held in tightly assembled relationship and thereafter secured permanently as to a mounting base 16, a mounting screw 17 passing through the insulating sleeve 13 and being threaded into the mounting base 16. A top pressure plate 18 is interposed between the screw 17 and the top of the stack assembly as seen.
The completed assembly shown in 'FIG. 6 can be operated by any sort of a device such as a plug, plunger, lifter, cams, or the like. The precise form of the operator for the switch arms 14 forms no part of the present invention.
Referring now to FIGS. 7 and 8, there is shown another t i Patented J 27,1961:-
form of insulating spacer indicated generally by the reference numeral 21. In this form of the invention the spacer has punched out circular openings 22 therein, there being tangs t tangent to a circle of smaller diameter than the diameter of the opening 22; As inthe embodiment disclosed in FIG. 2, such tangs t should preferably be tangent to a circle having a diameter whichis less than the outer diameter of circular opening 22, the major diameter of opening 22 being not less than the diameter of sleeve 13, the selection of the diameter being in accordance with the sleeve diameter and the thickness and the material of the spacer.
In either form of the invention, whether it be by the tangs seen in FIGS. 7 and 8 or by'the chordal surfaces seen in FIGS. 2 and 3, it is possible to maintain the assembly in assembled relationship for a relatively long period of storage time if necessary. In the usual case, and where the assemblies are not constructed as disclosed. as in this application, the loss of plasticizer in theinsulating members causes their dimension to change. Such change in dimension would, without the provision ofthe assembly securing means described herein, cause the assembly to become loosened particularly after periods of storage.
It will be noted that the insulating spacers are not characterized by slots extending from the edges toward the insulating sleeves. Such slots give rise to creep voltages across adjacent switching members, but a construction as disclosed herein greatly minimizes such an occurrence.
While the invention has been described in terms of a number of preferred embodiments thereof, its scope is intended to be limited only by the claims here appended.
'We claim as our invention:
1. In a switch stack assembly, an insulator spacer having at least one hole to accommodate an insulating sleeve, said hole being defined by a major diameter not less than the outside diameter of said insulating sleeve, and portions of slightly smaller diameter than said insulating sleeve comprising chordal portions tangent to a circle of minor diameter, each of said chordal portions being spaced angularly from each other, said chordal portions being adapted to be deformed when being placed on said sleeve so as to hold thespacer tightly to said sleeve in assembled relationship.
2. In a switch stack assembly, an insulator spacer having at least one hole to accommodate an insulating sleeve, said hole being defined by a principal diameter not less than the outside diameter of said insulating sleeve, and portions of slightly smaller diameter than said insulating sleeve, comprising tang portions tangent to. a circle of smaller diameter, said tang portions being adapted to be deformed when being'placed on said sleeve and hold the spacer andsleeve tightly. together in assembled relationship.
3. In a switch stack assembly, an insulator spacer having at least one hole to accommodate an insulating sleeve, said hole being defined by a principal diameter not less than the outside diameter of said insulating sleeve,
and portions of slightly smaller diameter than said insulating sleeve, comprising tang portions tangent to a circle of smaller diameter, each of said tang portions be.
ing spaced angularly from each other, said tang portions being adapted to be deformed when being placed on said sleeve and hold the spacer and sleeve tightly together in assembled relationship.
References Cited in the file of this patent UNITED STATES PATENTS 2,242,971 Glennon May 20, 1941'