U.S. patent number 3,676,626 [Application Number 05/046,390] was granted by the patent office on 1972-07-11 for pushbutton switch with liquid drainage facilitating cage body, and diaphragm sealing and actuating means.
This patent grant is currently assigned to TRW Inc.. Invention is credited to Edward B. Mitchell.
United States Patent |
3,676,626 |
Mitchell |
July 11, 1972 |
PUSHBUTTON SWITCH WITH LIQUID DRAINAGE FACILITATING CAGE BODY, AND
DIAPHRAGM SEALING AND ACTUATING MEANS
Abstract
This is a switch which includes a flexible diaphragm adapted to
flex when actuated by a plunger spring thereby providing both a
water-proof seal and part of the actuating system of the switch.
The switch body is formed of an upper circular member having an
axial hole formed therethrough and a lower circular member having
an axial hole formed therethrough, the two members connected by a
pair of legs which are in-spaced opposed relation to each other
provoding an open cage like configuration which will allow water to
drain outwardly and assist in waterproofing the switch.
Inventors: |
Mitchell; Edward B. (Belmont,
MA) |
Assignee: |
TRW Inc. (Cleveland,
OH)
|
Family
ID: |
21943194 |
Appl.
No.: |
05/046,390 |
Filed: |
June 15, 1970 |
Current U.S.
Class: |
200/534;
200/302.2 |
Current CPC
Class: |
H01H
13/06 (20130101); H01H 13/14 (20130101); F25D
2500/02 (20130101); F25D 29/005 (20130101) |
Current International
Class: |
H01H
13/06 (20060101); H01H 13/04 (20060101); H01H
13/14 (20060101); F25D 29/00 (20060101); H01h
013/06 () |
Field of
Search: |
;200/159R,159A,159B,168G,172A,153V,83N,83B |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
620,958 |
|
Apr 1949 |
|
GB |
|
1,306,689 |
|
Sep 1961 |
|
FR |
|
1,116,030 |
|
Jun 1968 |
|
GB |
|
1,073,267 |
|
Sep 1954 |
|
FR |
|
1,463,231 |
|
Dec 1968 |
|
DT |
|
1,162,909 |
|
Feb 1964 |
|
DT |
|
Primary Examiner: Schaefer; Robert K.
Assistant Examiner: Vanderhye; Robert A.
Claims
I claim:
1. A switch comprising an open cage body, having a series of
unrestricted openings around its periphery, the body having an
upper plunger holder, an intregal leg extending from each side of
the plunger holder, the legs being spaced from each other providing
the unrestricted openings and in spaced parallel opposed relation
to each other and to the axis of the switch and having an end and
each of said legs having a transversely arced inner surface and
said ends being joined by an intregal ring portion, a plunger
movably associated with the body, between said legs, and having a
plunger spring associated therewith, a contact assembly including a
case, a contact spring engaged with the case and with a movable
contact, at least one fixed contact, a flexible diaphragm directly
engaged with the plunger spring and the movable contact and
interposed therebetween, the case engaged to the body.
2. A switch as set forth in claim 1 wherein the diaphragm includes
a disc portion having an inner wall extending upwardly therefrom
and an outer wall extending from the inner wall forming an angle
therewith, and a tab portion extending from the outer wall on
substantially the same plane as the disc portion.
3. A switch as set forth in claim 2 wherein the disc portion has a
rod portion extending from one side and post portion extending from
the opposite side of the disc portion, the rod portion
circumscribed by the plunger spring and the post portion
circumscribed by the contact spring.
4. A switch as set forth in claim 3 wherein the plunger spring
abutts the disc portion of the diaphram and the movable contact has
an aperture formed therethrough and the post portion extends into
the aperture in the movable contact.
Description
BACKGROUND OF THE INVENTION
This invention is directed at door switches for refrigerators or at
switches which operate in a humid or somewhat damp environment.
Frequently, when a housewife cleans a refrigerator, she will take a
damp cloth and pass it over the switch which is set in the door and
which actuates the light in the refrigerator cabinet. This use of
water would cause ordinary switches to short circuit thereby giving
the person who is holding the cloth or sponge a shock.
DESCRIPTION OF PRIOR ART
The problem of short circuiting due to moisture has in the past
been solved in two ways. Either by the use of gaskets or 0-rings or
by the use of an external boot or cover diaphragm.
The use of a gasket to water-proof a switch is shown in the patent
to Long, U. S. Pat. No. 3,249,726. One of the difficulties in the
use of gaskets is that they require extra spring force which may
not be acceptable to refrigerator manufacturers because the extra
force may push the door open or may cause the switch plunger to
penetrate through thin door panels. Also in many switches using the
gasket approach, the plunger spring carries current and may
therefore be dangerous to a person using same.
Examples of the use of an external boot are shown in the patents to
Cooper, U. S. Pat. No. 3,146,329, West, U. S. Pat. No. 3,204,069,
and Miachon, U. S. Pat. No. 3,238,344. The use of the boot reduces
the plunger stroke to one of less than a half inch. Also the boot
takes up space and requires the use of more plunger force.
SUMMARY OF THE INVENTION
The applicant's water-proof switch utilizes an open cage
construction which guides the flow of moisture along the arms
causing the water to drip off away from the electrical mechanisms
due to the pull of gravity. As to moisture which flows along the
spring, this moisture is blocked by the diaphragm. The pull of
gravity is utilized by having the axis of the switch at right
angles to the pull.
An object of the present invention is to provide a switch which is
capable of preventing short circuiting by moisture.
A further object of the present invention is to provide a
water-proof switch which gains its ability to avoid short
circuiting through the use of a diaphragm and an open cage
construction.
A still further object of this invention is to provide a switch in
which the plunger spring is insulated from the current carrying
member.
Another object of the invention is to provide a switch having its
contacts set in a compartment separate from the plunger
compartment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded view of the switch.
FIG. 2 is a plan view of the contact assembly of the switch shown
in FIG. 1.
FIG. 3 is a perspective of the diaphragm.
FIG. 4 is a section of the switch.
FIG. 5 is a section of the switch with the plunger depressed.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The switch 10 comprises a plunger 12, a plunger spring 14, a body
16, a rubber diaphragm 18, a movable contact 22, a pair of fixed
contacts 24, a contact spring 26, and a case 20.
The body 16 includes a cylindrical plunger holder or upper portion
28 having a top surface and an annular flange 30 extending radially
from an end and forming a right angle with the plunger holder 28.
An aperture 32 is formed axially and centrally through the plunger
holder 28. A cavity is formed within the plunger holder 28 of
greater diameter than the aperture 32 and into which the aperture
32 opens. An integral leg 34 extends from each side of the plunger
holder 28. The legs 34 are in opposed relation to each other, in
spaced, parallel relation to the axis of the switch, and are spaced
from each other for the major portion of their length. Each of the
legs 34 has transversely arced inner and outer surfaces. An
integral ring portion 36 joins the legs 34 and provides a plane
which is spaced in parallel relation to the annular flange 30. Two
arms 38 extend from the ring portion 36 toward the flange 30. The
arms 38 are in spaced opposed relation to each other, with a leg 34
between them on each side, and each has a free terminal end as well
as a knuckle. Each of the legs 34 is continued beyond the ring
portion 36 by a thinned extension 40 having a rectangular opening
41 and the ring portion 36 is continued for the rest of its
circumference by a thinned skirt portion 42. The extension 40 and
the skirt portion 42 form an internal shoulder 44 with the ring
portion 36.
The plunger 12 comprises a tubular portion closed at one end and
having an annular flange 46 extending radially adjacent to the
other end which is open. The annular flange 46 has a skirt portion
extending therefrom, and the tubular portion has a diameter less
than the diameter of the aperture 32.
The diaphragm 18 includes a disc portion having a centrally located
rod portion 48 extending axially from one side and a cylindrical
post portion 50 extending axially from the other side. An inner
wall 52 extends upwardly and outwardly from the circumference of
the disc portion in spaced circumscribing relation to the rod
portion 48. An outer wall 54 extends from the far edge of the inner
wall 52 in angular relation therewith. The inner wall 52 and the
outer wall 54 provide a V-shaped aspect in cross-section. A tab
portion 56 extends from the free end of the outer wall 54 on the
same plane as the disc portion in right angle relation to the axis
of the diaphragm 18.
The contact assembly includes the case 20, the fixed and movable
contacts and the contact spring 26. The case 20 comprises a base
portion 58 having a circular wall 60 extending therefrom forming a
well or cavity. The wall 60 has a slot formed on each side to
accept a fixed contact 24. A projection 66 extends from the
external surface of opposed sides of the wall 60. The fixed contact
24 comprises a terminal portion and a contact portion which is a
continuation of the terminal portion having a contact 62 formed
therefrom and bent in an angular relation therewith. The movable
contact 22 is dome-shaped and has an opening 64 formed through its
apex. The contact assembly is put together by placing one terminal
end of the contact spring 26 against the base portion 58 of the
case 20. A protuberance or projection extending from the base
portion 58 will prevent the contact spring 26 from slipping
sidewards and will help center it when it is first placed within
the case 20. The movable contact 22 is placed over the contact
spring 26 with its apex directed away from the base portion 58. The
fixed contact will engage in the slot formed in the wall 60 with
each of the contacts 62 abutting in superimposed relationship a
portion of the movable contact 22.
The switch 10 is assembled by passing the tubular portion of the
plunger 12 through the aperture 32 in the body 16 until the annular
flange 46 butts against the portion of the plunger holder 28
adjacent the aperture 32. The plunger spring 14 is placed within
the tubular portion of the plunger 16 and extends axially
therefrom. The diaphragm 18 is placed over the case 20 with the
post portion 50 extending through the hole 64 in the movable
contact 22. The rod portion 48 is engaged to a terminal end of the
plunger spring 14 by placing the terminal end of the plunger spring
14 into the well formed by the disc portion and the inner wall 52
and into circumscribing relation with the rod portion 48.
The body assembly is engaged to the contact assembly by placing the
extensions 42 against the outer surface of the case 20 with the
skirt portion 44 circumscribing a portion of the case 20. An
external shoulder can be formed on the case 20 to act as a stop for
the free edge of the skirt portion 44. The projections 61 will
engage against the walls of the rectangular openings 41.
If an axial force is applied to the plunger 12, the plunger 12 and
the plunger spring 14 will move as a unit flexing the outer wall 54
of the diaphragm 18 downwardly toward the base 58. This movement
will force the movable contact 22 against the contact spring 26
which compresses breaking the engagement between the fixed contacts
24 and the movable contact 22. The plunger spring 14 requires more
force to compress than the contact spring 26. Once the contact
spring 26 has built up sufficient resistance, the plunger spring 14
will compress providing overtravel.
With reference to the foregoing description it is to be understood
that what has been disclosed herein represents an embodiment of the
invention and is to be construed as illustrative rather than
restrictive in nature and that the invention is best described by
the following claims:
* * * * *