US2747036A - Fluid-tight electric switches and waterproof separable conductor connecting means therefor - Google Patents

Description

y 2. 1956 H. N. BRODS ETAL 7,036

FLUID-TIGHT ELECTRIC SWITCHES WATERPROOF SEPARABLE CONDUCTOR CONNECTING MEANS THEREFOR Filed April 1 1954 FLUID-TIGHT ELECTRIC SWITCHES AND WATER- PROOF SEPARABLE CONDUCTOR CONNECT- ING MEANS THEREFOR Harry N. Brodsky and Blair H. Chamberlin, Detroit,

Mich.; said Brodsky assignor to Riverside Mfg. & Electrical Supply Co., Inc., Dearborn, Mich., a corporation of Michigan, and said Chamberlin assignor to Cutler- Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application April 12, 1954, Serial No. 422,563 Claims. (Cl. 200-51) This invention relates to fluid-tight electric switches and waterproof separable conductor connecting means therefore.

Our Patent No. 2,740,872, granted April 3, 1956, discloses and claims improved forms of fluid-tight electric switches and methods of making the same. The present invention constitutes an improvement thereon in respect of providing conductor connecting means, which are in part carried in the molded mass of electrical insulating material, in which the switch casing is embedded, and which are waterproof and readily separable.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates a preferred embodiment of the invention and various method steps in making the same, which will now be described in detail, it being understood that the embodiment illustrated and the steps used in making the same can be modified in respect of details without departing from the scope of the appended claims.

In the drawings:

Figure 1 is a view in side elevation showing certain initial steps in the process of making a fluid-tight electric switch in accordance with the invention.

Fig. 2 shows the assembly of Fig. I mounted in one part of a molding die preparatory to a molding step.

Fig. 3 shows in detail a core member used in connection with the die of Fig. 2.

Fig. 4 is a perspective view of a completed fluid'tight electric switch and connected conductor,

Fig. 5 is a fragmentary cross-sectional view taken along the line 5-5 of Fig. 4, and

Fig. 6 is an enlarged view of a plug-in connector shown in Figs. 4 and 5.

Referring to Fig. 1, it shows a switch 10 having a metal casing 11 for the commutating mechanism (not shown), a toggle lever actuator 12, a top metal mounting plate 13 which is riveted to the casing by rivets (not shown), and a bottom insulating plate 14. While not shown, it may be assumed that fluid-tight sealing means are provided for actuator 12 interiorly of casing 11 within the opening through which the actuator projects, or alternatively by sealing means extending about the actuator exteriorly of the casing as disclosed in our aforementioned patent. Switch 10 is provided with outwardly extending end terminal lugs 15 and 16 and a center terminal lug 17. Each of said terminal lugs is provided with a threaded opening extended therethrough, and as an initial step, assemblies, each comprising a brass male terminal stud 18, a brass disc washer 19, and a molded rubber female connector boots are secured to each terminal lug. The boots 20 are provided with bosses 20 having openings extending therethrough, and threaded end portions of studs 18, penetrating the openings in the washers and bosses 20 take into the threaded opening, to secure such assemblies in place as depicted in Fig. 1. Each of the boots is provided with a resilient hollow cylindrical pornited States Patent O l 2,747,036 Patented May 22, 1956 tion 20 which at its outer end is provided with an inwardly projecting circumferential lip portion 20.

After attachment of the aforementioned assemblies to each of the terminal lugs, the assembly thus elfected is subjected to cleaning, as by, bufling, grit blasting or by use of emery paper on the under side of plate 13, the casing 11, the plate 14 and the outer surfaces of the boots 20. Then the lower surface of plate 13, the casing 11, terminal lugs 15, 16 and 17 and plate 14 are coated with a suitable rubber-to-metal adhesive, and the outer surfaces of boots 20 are coated with a suitable rubber-to-rubber adhesive, and such coatings are then permitted to air dry at room temperature.

As shown in Fig. 2, internally threaded lock nuts 21, having flange portions 21, upper cylindrical portions 21 and a transversely slotted lower cylindrical portion 21 are inserted through the mounting holes 13 and 13 in top plate 13, with the flange 21 thereof seating against the lower side of plate 13 and the cylindrical portions 21 extending above the upper surface of plate 13. The assembly is then placed in the bottom part 22 of a molding die 22. The die 22 is similar to a molding die shown and described in connection with our aforementioned patent, but differs therefrom in having case hardened metal cores 23 for the boots 20, which retain the normal shape of the boots and proper placement of the same in the die during the molding operation. The cores 23, which are preferably of the form best shown in Fig. 2, are provided with lower cylindrical portion 23* having peripheral flanges 23 and upper cylindrical portion 23 of reduced diameter having an annular recess 23 and an axial recess 23 to accommodate a stud 18.

A core 23 is inserted into the open end of each boot 20 until the upper end of its cylindrical portion 23 seats against a washer 19, and the assembly is then placed in die part 22 as shown in Fig. 2, with the lower cylindrical portions 23 and peripheral flanges fitting into complementary semi-circular recesses 22 and 22 of die part 22.

Temporary securing screws 24 take into the nuts 21, and together with washers 25 underlying the heads of the screws are used to secure switch 10 in place in die part 22*. With the other half of die 22 (not shown) closed on the upper surface 22 of die part 22, the assembled die is then placed in a suitable molding fixture, and the same subjected to the injection or extrusion of plasticized rubber into the die casting as shown and described in our aforementioned patent; to which reference should be made for the details of the steps and means utilized for molding a mass of flexible rubber material about the switch casing and portions of the outer surfaces of the connector boots.

Following the molding and curing steps, and cutting-off of all excess rubber which extruded through relief openings in die 22, etc., the switch casing, terminal lugs and the greater part of the connector boots will be embedded in and intimately bonded with a substantially rectangular block of rubber 26, as depicted in Fig. 4. As will be seen from Fig. 4, portions 20 of the connector boots extend beyond one surface of the rubber block 26.

As shown in Figs. 4, 5 and 6, conductor leads, such as the flexible insulated leads 30, are adapted to be connected to the terminal studs 18, through the medium of plug-in connector assemblies generally designated 31. Each connector assembly comprises a longitudinally split metal, female connector 32, to which a conductor lead is attached, and into which a terminal stud 18 fits for electrical connection therewith. A hard plastic ferrule or sleeve 33 is fitted about connector 32 and sleeve 33 fits within the bore of a molded flexible rubber male plug 34. Plug 34 is provided with a cylindrical portion 34 which is slightly larger in diameter than the inside diameter of 's) portion 20 of boot 20 so as to elastically engage in a force fit therewith, and portion 34 is provided with a semi-circular annular groove 34 into which the lip portion 20 of boot 20 fits when plug 34 is pushed into engagement with the washer 18. At their lower ends the plugs 34 are provided with bosses 34 having openings through which conductor leads 30 extend in tight elastic fitting engagement.

The aforedescribed plug-in connectors 31 when fitted to flexible conductor leads permit ready making and breaking of electrical connection between the leads and switch terminals, which connections are of the self-sealing waterproof type which can be made and broken repeatedly.

'We claim:

1. A fluid-tight electric switch unit'comprising, a switch including'a'case for the 'commutating mechanism and an actuator extending through an opening in said case and a pluralityof external terminals, sealing means for said opening in said case constructed to'permit free operation of said actuator, a plurality of assemblies each of which is associated'with a respective terminal and comprises a hollow flexible rubber boot and a male connector stud electrically connected to its associated terminal and disposed concentrically within the bore of a boot, and a molded mass of elastic and moisture impervious insulating material in which said case, said terminals and a greater portion of the outer surfaces of said boots are embedded in bonded and sealed relation, said assemblies constituting built-in receptacle portions of separable connectors into which complementary plug-in portions may be waterproolly fitted to effect connection between said switch unit and conductor leads.

2. The combination according to claim 1 wherein said boots are secured to their associated terminals by said studs.

3. The combination according to claim 1 wherein said boots are substantially cylindrical in form and extend outwardly beyond the surface of said molded mass of insulating material to their open ends.

4. The combination according to claim 3 wherein said boots at their open ends are provided with inwardly projecting annular lips adapted to fit within complemental grooves in plug-in connectors fitted into said boots to facilitate waterproofing therebetween. t

5. In combination, a fluid-tight electric switch unit comprising a switch including a case for the commutating mechanism and an actuator extending through an opening in said case, and a plurality of external terminals, sealing means for said opening affording free operation of said actuator, a plurality of assemblies each of which is associated with a respective terminal and comprises a hollow flexible rubber boot and a male connector stud electrically connected to its associated terminal and disposed concentrically within'the bore of a boot and a molded mass of elastic and moisture impervious insulating material in which said case, said terminals and a greater portion of the outer surfaces of said boots are embedded in bonded and sealed relation, and at least one plug-in assembly comprising a hollow, substantially cylindrical member formed of elastic material fitted into and engaging the inner wall of such boot with an elastic forcefit, a female electrical connector concentrically disposed in said member which interfits with the connector stud associated with-such boot, and a conductor lead connected to said female connector and extending through an opening in a substantially closed end of said member with an elastic force-fit.

References Cited in the file of this patent UNITED STATES PATENTS 2,377,628 Hallett June 5, 1945 2,379,942 Webber July 10, 1945 2,400,849 Stearns .a May 21, 1946 2,416,143 Borgerd et al Feb. 18, 1947 2,633,510 Schellman Mar. 31, 1953 2,644,061 Dietrich June 30, 1953 FOREIGN PATENTS 329,447 Great Britain May 22, 1930

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