U.S. patent number 3,902,032 [Application Number 05/477,219] was granted by the patent office on 1975-08-26 for electrical switch with improved contact structure.
This patent grant is currently assigned to Illinois Tool Works Inc.. Invention is credited to John A. Koepke.
United States Patent |
3,902,032 |
Koepke |
August 26, 1975 |
Electrical switch with improved contact structure
Abstract
An electrical switch with an improved contact structure of the
type having a depressible plunger with a contact separator for
separating two flexible contacts when the plunger is in one
position and for allowing the contacts to close when the plunger is
in a second position is disclosed. The improved contact structure
consists of two identical bifurcated contacts, one arm of which has
a flat contact surface and the other arm of which has a curved
contact surface. The contacts are positioned so that the curved arm
of each contact engages the flat arm of the other contact when the
switch is closed.
Inventors: |
Koepke; John A. (Des Plaines,
IL) |
Assignee: |
Illinois Tool Works Inc.
(Chicago, IL)
|
Family
ID: |
23895018 |
Appl.
No.: |
05/477,219 |
Filed: |
June 7, 1974 |
Current U.S.
Class: |
200/506; 200/283;
200/533 |
Current CPC
Class: |
H01H
1/26 (20130101); H01H 1/24 (20130101); H01H
15/102 (20130101); H01H 13/10 (20130101); H01H
1/50 (20130101) |
Current International
Class: |
H01H
1/26 (20060101); H01H 13/10 (20060101); H01H
1/12 (20060101); H01H 15/00 (20060101); H01H
13/02 (20060101); H01H 15/10 (20060101); H01H
1/24 (20060101); H01H 1/00 (20060101); H01H
1/50 (20060101); H01h 013/52 (); H01h 001/26 () |
Field of
Search: |
;200/159A,153M,153LA,159R,275,279,283,246,61.19 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schaefer; Robert K.
Assistant Examiner: Smith; William J.
Attorney, Agent or Firm: Beart; Robert W. Bowen; Glenn
W.
Claims
The invention is claimed as follows:
1. In an electrical switch comprising a housing, a depressible
plunger, means for biasing the plunger to its undepressed state and
a separator member which is depressible when said plunger is
depressed; an improved contact structure comprising first and
second contacts secured in said housing each of which comprise an
angled section which provides a bias on said contacts that tends to
force said contacts towards each other, and a bifurcated contact
portion consisting of a first arm on each contact having an arcuate
curved contact surface and a second arm on each contact having a
substantially flat contact surface wherein the curved contact
surface of said first arm of said first contact is positioned so as
to engage the flat contact surface of said second arm of said
second contact and the curved contact surface of said first arm of
said second contact is positioned so as to engage the flat contact
surface of said second arm of said first contact when said first
and second contacts are closed by movement of said separator member
due to depression of said plunger to a position where it no longer
separates said first and second contact members from each other.
Description
BACKGROUND OF THE INVENTION
One particularly simple but effective type of electrical pushbutton
switch is constructed with a depressible plunger which has a
separator member formed on it that is disposed between two
contacts. The contacts are shaped so that they are normally biased
toward each other. When the plunger has not been depressed, the
separator member maintains the contacts separate so the switch is
open; but when the plunger is depressed, the separator member moves
downwardly so it is no longer in contact with the angled contact
arms; and they are thereby allowed to engage each other to close
the switch. In the described type of switch there is a tendency for
the contacts to bounce when the arms contact each other. In
addition, prior contact structures do not generally provide
sufficient wiping action between the two contacts so as to keep the
contact surface adequately clean. The contact structure of the
present invention is designed to increase the reliability of the
described type of switch while reducing the contact bounce problem
and providing for increased wiping action.
It is, therefore, the object of the present invention to provide an
improved contact structure for an electrical switch in which two
contacts are positioned in the switch so that they are normally
biased towards each other, and a plunger with a separator member on
it determines whether or not the two contact members remain
separated or closed, wherein the improved contact structure is
provided by two contacts which are identical and which have
bifurcated ends constructed so that one arm of each contact is flat
and the other arm of each contact is curved with the contacts being
aligned so that the curved arm of each contact engages the flat arm
of the other contact when the switch is closed.
DESCRIPTION OF THE DRAWINGS
The present invention is illustrated by reference to the drawings
in which:
FIG. 1 is a top view of a switch employing the improved contact
structure of the present invention;
FIG. 2 is a perspective view of the improved contact structure of
the present invention removed from the switch of FIG. 1;
FIG. 3 is a cross-sectional view of the switch of FIG. 1 with the
plunger in an undepressed position and the contacts in an open
position; and
FIG. 4 is a cross-sectional view of the switch of FIG. 1 with the
plunger depressed and the contacts in a closed position.
TECHNICAL DESCRIPTION OF THE INVENTION
A switch 10 constructed in accordance with the present invention is
shown in FIGS. 1, 3, 4. The switch 10 comprises a housing 12 which
has an upper panel member 14 formed with a boss 16 that has a
central aperture 18. A plunger 20 is inserted into the central
aperture 18 of the boss 16, which has a rim 21 that surrounds it so
as to engage it to the upper end of a return spring 23. The lower
end of the return spring 23 is retained in the groove 24 formed in
the interior of the housing 12. A pair of contacts 28, 30 are
secured into the housing 12 with the upper contact portion 32 of
the contacts 28, 30 extending into an internal cavity 26 and the
plunger 20. The housing 12 is preferably formed of a plastics, and
the contacts 28, 30 are preferably secured into the housing 12 by
molding the sections 29, 31 of the contacts 28, 30 into the housing
12 when it is formed.
The contacts 28, 30 have angled sections 34, 36 between the contact
portion 32 and the molded in sections 29, 31 which slope towards
each other. The angled sections 34, 36 are biased towards each
other so that they tend to engage each other. The plunger 20 of the
switch 10, however, carries a separator member 27 which contacts
the angled sections 34, 36 of the contacts 28, 30 when the plunger
is not depressed so as to maintain the contacts 28, 30 open, as
shown in FIG. 3. The plunger 20 is preferably formed of plastics
and the separator member 27 is preferably integrally formed on the
plunger 20. When the plunger is depressed, as shown in FIG. 4, the
separator member 27 is lowered below the point where it no longer
contacts the angled sections 34, 36 and the contacts 28, 30 are
thereby allowed to close.
The improved contact structure of the present invention is best
shown by reference to FIG. 2. The contacts 28, 30 are constructed
with a pair of bifurcated arms 42, 44 and 38, 40 respectively. The
bifurcated arms 40, 42 are formed with arcuate curved contact
surfaces on the outer end of the straight segments 46 while the
arms 38, 44 have substantially flat contact surfaces which engage
the opposing curved contact surfaces 42, 40, respectively.
The design of the illustrated contacts 28, 30 provides a contact
structure that has low contact bounce and increased reliability
because of the bifurcated construction of the contact arms. The
manufacturing cost of the contacts of the present invention is
relatively low, since the arms 38, 40, 42 and 44 are integrally
formed on the contacts 28, 30. An additional feature of the contact
structure of the present invention is that while the contacts 28,
30 are designed to be identical, the actual contacts will be
slightly different due to manufacturing tolerances. This slight
difference will provide slightly unbalanced forces that will aid in
providing wiping action between the contact members 38, 42 and the
contact members 40, 44 as they settle to their equilibrium
positions.
* * * * *