US2814703A - Sealed switch - Google Patents

Description

1957 w. A. MARTIN 2,814,703

SEALED swncn Filed July 18. 1955 INVENTOR. WILBERT A. MARTIN @MUZM ATTORAE Y United States 3mm P SEALED SWITCH Wilbert A. Martin, Denver, Colo., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn a corporation of Delaware Application July 18, 1955, Serial No. 522,658

9 Claims. (Cl. 200-168) This invention relates :to sealed switches and more particularly to means :for providing movement through'the seal for actuating the'switch.

In many switch applications it is necessary to isolate the switching mechanism from its environment to :assure reliable switch operation. The problem revolves largely around the structure to be employed to transmitmovement to the switching mechanism. In the present invention a standard plunger actuated unitary switchis enclosed by a housing and a flexible seal closing an opening in the housing over the switch plunger has the additional function of forming a seal between the housing .and'the'switch case. The space between the switch case and :the housing is filled with a potting material, but the potting material is isolated from the space surrounding the plunger by the flexible seal. Hence, the switch is .sealed to a degree closely approaching a true hermetic seal, while avoiding the necessity of employing the costly structure and manufacturing procedures necessary to attain a 'true hermetic seal.

The object of the invention is to provide a sealed switch that is adapted .formanufacture insmall sizes, that is-economical to manufacture and is of rugged construction.

Other objects will be evident from the specification and claims and from the drawing in which Figure 1 is a sectional elevation of asealed switch incorporating the invention, and

'FigureZ is a fragmentary section taken 01111116 22 of Figure l.

A unitary snap action switch 11) including a plastic base 11 and a plastic cover 12 is disposed within a drawn sheet metal housing 15. The switch is provided with mounting holes 16 and 17 which are aligned with corresponding holes in the housing 15. Switch 10 has an actuating plunger 19 surrounded by a boss 20 formed in the cover 12. Terminals 21 extend from the base 11 and suitable lead wires 22 are connected thereto. The switch 10 may be of the type disclosed in my Patent 2,644,052 which, as manufactured, has a thickness of A of an inch and a length of of an inch.

The housing is formed with a circular opening therein concentric with the plunger 19, the rim of the housing at the opening being of toroidal configuration and spaced uniformly from boss on the case of the switch 10. This opening in housing 15 is closed by -a sealing member which comprises a cup shaped portion 26 of silicone rubber and a metal insert 27, the portion 26 being moulded to the insert 27 to form a unitary impervious sealing member. The insert 27 has a downwardly extending projection 27a that is received in a complementary recess in the plunger 19 so that the insert is, in effect, an extension of the plunger. The rim of the cup shaped portion 26 of member 25 is compressed between the rim of the housing 15 and the boss 20 on the switch case and may also engage a portion of the upper surface of the switch cover surrounding the boss 20. The annular part of cup shaped portion 26 intermediate its rim and the 2,814,703 Patented Nov. 26, 1957 2 insert "27 is adapted to act as adiaphragm to permit actuationo'f the switch plunger.

'An epoxy resin 30 is used as potting material and fills the space between the housing '15 and the switch case 10 with the exception of the annular area around plunger 19 dammed off by the sealing member 25. A suitable sealing material is applied to-the juncture between base 11 and cover 12 of switch 10 to prevent entry of the epoxy resin within the switch case prior toits solidification. The epoxy resin, inaddition tocomp'letely sealing the switch case, also seals the periphery of the sealing member 25, thus preventing passage of foreign material from outside the housing to the plunger-opening in the switchcase.

I-claim:

1. Ina sealed switching device, aswitch unit comprising a case and an actuatingplungerextending throughsaid case, a housing enclosing said switch unit, said housing having an opening therein :at said plunger, means closing the opening includinga first portion engaging said housing in an annular area aroundthe opening, a second portion overlying said plunger, a third portion intermediate said first and second portions adapted to act as a-diaphragm to permit movement of saidsecond portionto actuate'said=switch, and a fourth portion-engaging the switch case-in a continuous area spaced fromand encompassing said plunger.

"2. in escaled switching device, a switch unit comprising a-"case and-anactuating plungerextending through said case, a housing enclosing said switch unit, said housing having an opening therein'zat said plunger, means closing the opening including a first portion engaging said housingin an annular areaaround the opening, a second portion overlying said plunger, a third portion intermediate said first and second portions adapted to act as a diaphragm to permit movement of said second portion to actuate said switch, and a fourth portion engaging the switch case in a-continuous area spaced from and encompassing said plunger, the first, third and fourth portions of said closing means being a unitary body of resilientelas'tomer. d

3. ina :sealed switching device, a switch unit comprising a case and an actuating plunger extending through said case, a housing enclosing said switch unit, said housing having an opening therein at said plunger, means closing the opening including a first portion engaging said housing in an annular area around the opening, a second portion overlying said plunger, a third portion intermediate said first and second portions adapted to act as a diaphragm to permit movement of said second portion to actuate said switch, and a fourth portion engaging the switch case in a continuous area spaced from and encompassing said plunger, said closing means and said switch case cooperating to provide a space surrounding said plunger beneath the third or diaphragm portion of said means.

4. In a sealed switching device, a switch unit comprising a case and an actuating plunger extending through said case, a housing enclosing said switch unit, said housing having an opening therein at said plunger, means closing the opening including a first portion engaging said housing in an annular area around the opening, a second portion overlying said plunger, a third portion intermediate said first and second portions adapted to act as a diaphragm to permit movement of said second portion to actuate said switch, and a fourth portion engaging the switch case in a continuous area spaced from and encompassing said plunger and potting material within said housing embedding said switch case in said housing with the exception of the portion thereof adjacent said plunger dammed oil by said closing means.

5. In a sealed control device, a control unit comprising a case and an actuator extending through said case, a housing enclosing said control unit, said housing having an opening therein at said actuator, means closing the opening including a first resilient elastorner portionem gaging said housing in an area aroundthe opening, a second portion adapted to move-said actuator, a third resilient elastomer portion intermediate said =first andsecond portions adapted topermit relative motion of said first and second portions, and a fourth resilient elastomer portion engaging said case in a continuous area spaced from and encompassing said actuator.

6. In a sealed control device, a control unit comprising a case and an actuator extending through said. case, a housing enclosing said control unit, said housing having an opening therein at said actuator, means closing the opening including a first resilient elastomer portion engaging said housing in an area around the opening, a second portion adapted to'move said actuator, a third resilient elastomer portion intermediate said first and second portions adapted to permit relative motion of said first and second portions, and a fourth resilient elastomer portion engaging said case in a continuous area spaced from and encompassing said actuator, and potting'material within said housing embedding said case in said housing with the exception of the portion thereof enclosed by said closing means.

7. In a sealed switching device, a switch unit comprising a case and an actuating member movable in said case,

a housing enclosing said switch unit, said housing having an opening therein aligned with 'said actuating member, sealing means closing the opening including a portion engaging said housing in an annular area around the opening, a portion operatively engaging said actuating member and movable to actuate the switch, a portion intermediate said first two mentioned portions adapted to act as 21 diaphragm to permit movement of said actuating member, and a further portion engaging the switch case in a continuous area spaced from and encompassing said actuating member.

8. In a sealed switching device, a switch unit comprising a case and an actuating member extending through said case, said case having a portion surrounding said actuating member presenting an abutment surface facing outwardly from and surrounding said actuating member, a housing enclosing said switch case and spaced therefrom, said housing having an opening therein aligned with said abutment surface on said case, sealing means closing the opening including a portion engaging said housing in an area around the opening, a portion operatively engaging said actuating member and movable to actuate the switch, a portion intermediate said first two mentioned portions adapted to flex to permit movement of said actuating member, and a further flexible portion engaging the abutment surface of said switch in a continuous area encompassing said actuating member, and potting material within said housing embedding said switch case in said housing with the exception of the portion of said case adjacent said actuating member dammed ofi by said sealing means.

9. In a sealed switching'device, a switch unit comprising a case and an actuating member extending through said case, said case having a portion surrounding said actuating member presenting an abutment surface facing outwardly from and surrounding said actuating member, a. housing enclosing said switch case and spaced therefrom, said housing having a plurality of apertures disposed in opposite spaced portions thereof in aligned pairs, said switch case having apertures therein each aligned with an aligned pair of apertures in said housing, sealing means closing the opening including a portion engaging said housing in an area around the opening, a portion operatively engaging said actuating member and movable to actuate vthe'switch, a portion intermediate said first two mentioned portions adapted to flex to permit movement of said actuating member, and a further flexible portion engaging theabutment surface of said switch in a continuous area encompassing said actuating member,

3 and potting material Within said housing embedding said switch case in said housing with the exception of the portion of said case adjacent said, actuating member dammed ofi by said sealing means, said potting material having apertures therein in alignment with corresponding aper- 1 tures in said housing and said switch case, and cooperating therewith to provide continuous apertures through the device.

References Cited in the file of this patent UNITED STATES PATENTS 2,740,872 Brodsky et al. Apr. 3, 1956

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