Waterproof electric switch assembly

Abstract

A waterproof electric push button switch assembly having a closed compartment and an electric switch housed inside the closed compartment, the electric switch having connected thereto cables coming out of the compartment which is arranged inside a casing with a cavity with two openings, a first opening hermetically sealed by a compressible elastomeric body attached to the casing, and a second opening hermetically sealed by a cover. The elastomeric body extends into the cavity of the casing providing a surface supporting the electric switch and the cover has on its inner face a tubular wall which is inserted into the cavity of the casing and contacts the elastomeric body along the perimeter. The tubular wall completely surrounds the switch and assures its waterproofness.

Claims

1. A waterproof electric push button switch assembly comprising: a closed compartment; and a printed circuit board supporting an electronic push component housed inside said closed compartment, said printed circuit board having connected thereto two insulated electrical conductors coming out of said closed compartment, wherein said closed compartment is defined inside a casing comprising a cavity with two openings, a first opening and a second opening, said first opening being hermetically sealed by a compressible elastomeric body having a portion which is arranged facing said electronic push component, said compressible elastomeric body being attached to said casing, and said second opening is hermetically sealed by a cover, said first opening is arranged opposite to said second opening; said compressible elastomeric body extends partially into said cavity of said casing providing an inner portion with an annular flange which is placed against an inner face of said casing adjacent to said first opening of said casing; said printed circuit board supporting said electronic push component is fitted in a recessed portion of said compressible elastomeric body; and said cover comprises on an inner face at least one tubular wall which is inserted into said cavity of said casing and establishes with a free edge thereof a perimetral interference contact with a surface of said compressible elastomeric body, said tubular wall of said cover completely surrounding said printed circuit board, and wherein said two insulated electrical conductors come out through a side window of said casing which is occupied by an extension of said elastomeric body and through which said insulated electrical conductors pass.

2. The waterproof electric push button switch assembly according to claim 1, wherein said compressible elastomeric body further comprises a tubular wall extending outside of said cavity of said casing until establishing a perimetral interference contact with the inner face of said cover.

3. The waterproof electric push button switch assembly according to claim 2, wherein said tubular walls of said compressible elastomeric body and of said cover are of different widths and fitted together.

4. The waterproof electric push button switch assembly according to claim 2, wherein said casing is rigid, with said first and second openings arranged opposite one another and said compressible elastomeric body has a bend with a flat inner face which is placed against a part of said inner face of said casing surrounding said first opening, said flat inner face of said bend being pressed by said tubular wall of said cover.

5. The waterproof electric push button switch assembly according to claim 4, wherein said tubular wall of said elastomeric body emerges from said flat inner face of said bend.

6. The waterproof electric push button switch assembly according to claim 1, wherein said printed circuit board is fitted in an inner portion of said compressible elastomeric body.

7. The waterproof electric push button switch assembly according to claim 6, wherein said cover has an inner face, said inner face having, in a central area, a projection extending into said cavity of said casing and providing a support for said printed circuit board.

8. The waterproof electric push button switch assembly according to claim 1, wherein said compressible elastomeric body is made of an elastomeric thermoplastic material operative in a temperature range of −85° C. to +85° C.

9. The waterproof electric push button switch assembly according to claim 1, wherein said casing is a rigid casing, with said first and second openings arranged opposite one another, and said compressible elastomeric body attached to said first opening of said casing by overmoulding, comprising said flange providing said surface, said flange being placed against a part of said inner face of said casing surrounding said first opening.

10. The waterproof electric push button switch assembly according to claim 1, wherein said compressible elastomeric body furthermore has attached thereto by overmoulding an outer part configured as a push button.

11. The waterproof electric push button switch assembly according to claim 1, wherein said cover is fixed to said casing by means of an ultrasonic weld bead.

12. The waterproof electric push button switch assembly according to claim 1, wherein said cover is fixed to said casing by a mechanical fastening.

13. The waterproof electric push button switch assembly according to claim 12, wherein said mechanical fastening is provided by side appendages of said cover which are inserted into said cavity of said casing, adjacent to two opposite inner walls, and anchored inside openings of said walls.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing and other advantages and features will be fully understood based on the following detailed description of several embodiments in reference to the attached drawings which must be interpreted in an illustrative and non-limiting manner, in which:

(2) FIG. 1A is a sectioned perspective view of an electric switch assembly of the invention according to a first embodiment.

(3) FIG. 1B is a sectioned perspective view of the casing showing the first opening and second opening of the casing.

(4) FIG. 2 is a perspective view of the electric switch assembly of FIG. 1A through its lower face, with the closure cover having been eliminated, which allows seeing a printed circuit board supporting the electronic switch component or device, and insulated electric cables which are connected to said board.

(5) FIG. 3 is a perspective view of the switch assembly of the two preceding figures, showing the push button portion and the insulated electric cables exiting the casing.

(6) FIG. 4 is a perspective view of the closure cover of the second opening of the casing, showing the tubular wall which is derived from the inner face of this cover and the sealing lip which determines its free edge and will preferably have a rounded cross-section.

(7) FIG. 5 is a sectioned perspective view of an electric switch assembly of the invention according to a second embodiment.

(8) FIG. 6 is a perspective view of the electric switch assembly of FIG. 5 through its lower face, with the closure cover having been eliminated, which allows seeing a printed circuit board supporting the switch, the tubular wall emerging from the elastomeric body surrounding said printed circuit board, and insulated electric cables which are connected to said printed circuit board and extend to the outside, passing through an extension of the elastomeric body which is arranged in a side opening of the casing.

(9) FIG. 7 is a perspective view of the switch assembly of the embodiment of the two preceding figures, showing the push button portion and the insulated electric cable exiting the casing.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

(10) In the first embodiment shown in FIGS. 1 to 3, a structure and/or design of the mentioned electric switch assembly 10 is proposed, said assembly being envisaged to show an external push button element 15, i.e., the button which the user will push and which will subsequently actuate an electronic push component or device 30 encapsulated inside the switch assembly 10.

(11) Said external push button element 15 and the casing 11 are attached by an elastomeric body 12 which is overmolded with respect to both the element 15 and the casing 11, closing one of its openings, such that the entry of water into the casing and said elastomeric body 12 is prevented as long as there exists between both a chemical adhesion resulting from overmolding and chemical compatibility. A closure cover 13, which will be described in detail below, closes a second opening—of the casing 11, directly opposite the first opening. The elastomeric body comprises a portion 12a which is arranged facing a push button part of the electronic push component 30, allowing the actuation thereof upon deformation, acting on the mentioned external push button 15. The part of the elastomeric body 12 which is arranged inside the cavity of the casing furthermore has an annular flange 12b which is placed against an inner face of the casing adjacent to the first opening of the casing 11.

(12) FIG. 2 shows the mentioned switch assembly 10 in which the closure cover 13 has been eliminated, which allows seeing (through the second opening 11b of the casing 11) inside the cavity of the casing 11 a printed circuit board 14 which supports the electronic switch component or device and to which there are attached by welding the ends of insulated electrical conductors 16 or cables passing to the outside through a side window 17 of the casing 11 which is occupied by an extension 12c of the overmolded elastomeric body 12, such that the electrical conductors 16 are embedded through said extension 12c (see FIG. 3), and therefore the watertightness of said passage is assured.

(13) The mentioned second opening is closed by the cover 13 which can be sealed by means of ultrasound, by means of a harpoon-type closure (appendages of the cover which are interlocked in the walls of the casing 11), or even by means of an adhesive, this should be avoided.

(14) According to the proposal of this invention, the mentioned cover 13 comprises on its inner face a tubular wall 18 (in this case having a rectangular cross-section) which is inserted into the cavity of the casing 11 until establishing a perimetral interference contact, with its free edge (advantageously having a rounded transverse profile) pressing on a surface of the elastomeric body (provided by the annular flange 12b attached by overmolding to the inner face of the cavity of the casing 11, adjacent to the first opening, this tubular wall 18 of the cover 13 completely surrounding the mentioned printed circuit board 14 bearing the electronic push component 30 and fitted in an inner portion of the elastomeric body 12, thereby assuring waterproofness.

(15) Assuring that the elastomeric body 12 is pressed, along the perimeter, into the entire contour of the location of the electronic push component 30 is of utmost importance, and for this reason the tubular wall 18 of the cover 13 must adapt to said elastomeric body 12 despite the existence of changes in height caused by interaction with the insulated electrical conductors 16. FIG. 4 shows the terminal profile of said wall 18, where it can be seen that the wall has a perimetral lip or arch-shaped part designed to allow the passage of the cables 16 therethrough.

(16) Furthermore, in the solution of the first embodiment the cover 13 has a projection or partition 19 located in the central part of its inner face, which projection supports the printed circuit board 14, keeping it in place, fitted in the inner portion of the elastomeric body 12 (see FIG. 1), but at the same time prevents the printed circuit board 14 from having a support and opposite reaction force when a force is imparted on the push button part of the electronic push component 30, and the latter on the printed circuit board 14.

(17) FIGS. 5 to 7 show a second embodiment in which the same principle of the invention is applied, although in this case, the elastomeric body 12 does not have to be overmolded, reducing the cost of the manufacturing process as indicated and obtaining similar watertightness conditions.

(18) In this second embodiment, the elastomeric body 12 is introduced in the cavity of the casing 11 with its push button portion emerging through the mentioned first opening 11a and being retained therein by the flat face of a bend 12d being supported on an inner edge of the cavity adjacent to said opening 11a, and the printed circuit board 14 is likewise fitted in the inner portion of this elastomeric body 12, in the area demarcated by the bend 12d.

(19) In this case, the cover 13, in addition to having a tubular wall 18, the free edge of which (having a rounded transverse profile) presses on the mentioned flat face of the bend 12d of the elastomeric body 12, completely surrounding the electronic component or device of the switch, the polymeric body 12 itself has another tubular wall 20 extending towards the outside of the cavity of the casing 11 until establishing a perimetral interference contact with the inner face of said closure cover 13 of the second opening 11b, pressing on said inner face.

(20) As can be seen in FIG. 5, the tubular walls 18 and 20 of the elastomeric body 12 of the cover 13 are of different width, located very close to one another, and fitted together.

(21) The same FIG. 5 shows an example of the cover 13 being attached to the casing 11 by means of an interlocking of grips or appendages 21 of the cover in the side openings 22 of the casing 11. Given the use of the double barrier provided by the mentioned walls 18, 20, the watertightness of the electronic component or device of the switch associated with the mentioned printed circuit board 14 is assured.

(22) FIG. 6 is similar to the view of the mentioned FIG. 2 showing the printed circuit board 14 arranged fitted in the central portion of the elastomeric body 12 which is arranged inside the cavity of the casing 11. The tubular wall 20 which is derived from the elastomeric body 18 and extends to the outside until pressing on the inner face of the cover 13, as explained in reference to FIG. 5, can be seen in this view. The cables 16 exiting through the elastomeric body extending towards a side window made on the casing 11 can also be seen.

(23) FIG. 7 is similar to FIG. 3 and shows the switch assembly with its upper section which works as a push button being seen.

(24) One advantage of this second embodiment is that due to the absence of attachment of the elastomeric body by overmolding, it is not necessary to use elastomers for said elastomeric body which are compatible with the material of the casing, which is usually a polymeric material.

(25) It will be understood that the different parts constituting the invention described in an embodiment can be freely combined with parts described in other different embodiments even though said combination has not been explicitly described, provided that such combination is not detrimental.

(26) Likewise, it must be indicated that the teachings of this invention are applicable for sealing other electrical or electronic components or devices included in a closed compartment from water.