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Патент USA US3019322

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Jan. 30, 1962
H, G, LEUPOLD
' 3,019,312
SNAP ACTION ELECTRICAL SWITCH
Filed Sept. 5, 1959
.
INVENTOI".
?ery 6. £02400”
BY
cgfiwéw
147775
United States Patent 0 " 1C6
3,919,312
Patented Jan. 30, 1952
1
2
3,019,312
element without requiring that the operating pin be re
strained r'rom rotation.
Further objects of the present invention are to provide
a switch of extreme sensitivity which will incorporate a
SNAP ACTION ELECTRICAL SWITCH
Henry G. Leupold, Arlington, Mass, assignor to United
Eleetric Controls Company, Watertown, Mass, a cor
poration of Massachusetts
force-transmitting mechanism of simple and inexpensive
construction including an operating pin of circular cross
Filed Sept. 3, 1959, Ser. No. 837,974
8 Claims. (Cl. 200-67)
section.
.
According to the present invention the operating pin
bears pivotally upon a transverse force-transmitting mem
This invention pertains to electrical switches of the
snap action type and more especially to improvements in 10 ber which, in turn, bears pivotally upon the arms of the
tensioning element. In a transverse plane, this force
the type of switch illustrated and described in the patent
transmitting element acts as a beam balance, distributing
to Frederick J. Broch, No. 2,729,715, dated January 3,
the force applied by the operating pin to each of the arms
1956.
of the tensioning element equally. By the nature of this
Such switches employ an unstable spring and linkage
mechanism constrained so that a free end of the spring 15 balancing action the forces applied to the two arms are
equal despite any relative vertical displacement and de
can move only a relatively short distance in either direc
spite any inequality in the de?ections of the arms as the
tion from the balanced position. In operation, a pivot
force is applied.
is moved until the system is unbalanced in a direction in
In the preferred embodiment the transverse force-trans
which motion is possible. The free end of the spring then
suddenly snaps in that direction and remains in that posi 20 mitting and distributing element is not attached either to
the actuating pin or to the arms of the tensioning element,
tion until the pivot is moved into the complementary un-'
but is loosely connected to the body of the switch only,
balanced position.
at a point spaced somewhat from the actuating pin, and
In the Broch switch the movable pivot and the linkage
is free to pivot and tilt transversely about this point ex
are combined in a tensioning element consisting of a piece
of thin ?exible sheet metal of generally rectangular con 25 cept as restrained laterally by the sides of the cover to
the switch and as restrained vertically by the arms of
tour having a large elongate central opening thereby de
the tensioning element below and the actuating pin above.
?ning a pair of transversely narrow, generally parallel
For the purpose of illustration, a typical embodiment
arms connected at their ends by transverse web portions.
the invention is shown in the accompanying drawings
One of the transverse webs includes hinge means for at
tachment to the free end of the spring and the other such 30 in which:
FIG. 1 is a side elevation;
FIG. 2 is a plan view with the cover removed and
with parts broken away.
FIG. 3 is a side elevation with the cover in vertical
web is secured to the switch case.
The switch also comprises an externally accessible mov
able part as, for example, an axially movable pin and
means for transmitting the motion of the pin to the arms
of the tensioning element.
35
section;
FIG. 4 is a fragmentary vertical section through the
cover, showing a modi?cation of the actuating pin;
FIG. 5 is a plan view of the transverse balancing ele—
greatest possible length for the tensioning element in a
case of standard dimensions. The movable contact is ac
ment;
FIG. 6 is a plan view of the tensioning element to
cordingly attached to one side of the tensioning element 40
smaller scale than FIG. 2;
and located between vertically spaced ?xed contacts at
In a snap switch of this type it is desirable that the
switch contacts be placed o?E-center so as to obtain the
FIG. 7 is a section on the line 7-7 of FIG. 6;
FIG. 8 is a section, to larger scale, on the line 8-8 of
tached t0 the base of the switch. In such an arrangement,
where the contacts are located unsymmetrically, there
is a ‘tendency for the tensioning element to warp slightly
due to the normal pressure of the movable contact against
FIG. 3; and
the upper ?xed contact, and thus one arm of the tension
scale, showing, in exaggerated position, the force-transmit
FIG. 9 is a fragmentary transverse section, to larger
ting member and the arms of the tensioning element.
Referring to the drawings, and particularly FIGS. 1-3,
the actuating force is then applied to the arms by a trans
the base 1 of the switch consists of a generally rectangular
verse element rigidly connected to the operating pin, some
of the work energy available to operate the switch may be 50 substantially rigid block of an appropriate dielectric mold
able material such as Bakelite, its external dimensions
wasted in restoring the tensioning element to a horizontal
preferably being those which have become a standard for
plane, thus causing a loss of sensitivity.
snap switches of this general type, for instance, of a
A further objection to having the operating force ap
length of 11%;”, a width of 11/16”, and a depth, with
plied to the ‘arms by a transverse element rigidly con
nected to the operating pin is that, in order to preserve 55 cover, of 1%6", with the axis of the actuating pin at a
distance of approximately 1/2” from one end.
the point of contact between the transverse element and
At the right-hand end of the base, ‘as viewed in FIGS.
the arms of the tensioning element, it is necessary to pre
2 and 3, are two vertically spaced contacts 2 and 3, the
vent any rotation of the operating pin. The Broch pat~
ing element may normally be higher than the other. If
upper contact 2 being supported directly above the lower
ent proposes to accomplish this, either by making the
operating pin of non-circular cross-section or by provid 60 contact 3 by bracket means 4.
An abutment 5, carried by the base, has at its right
ing the transverse element with laterally projecting lugs
hand end, a V-shaped groove for receiving the stationary
for engagement with vertical grooves in the inner surface
end 6a of the compression spring 6. The left-hand end
of the side walls of the cover. Both of these methods
of the abutment has an opening therethrough for a screw
are expensive and both have a tendency to cause binding
in the travel of the operating pin.
65 7 whereby the abutment is secured to the base 1.
Accordingly, objects of the present invention are to pro
vide means for distributing an operating force equally
between the two arms of the tensioning element without
regard to their relative vertical disposition or to any in
equality in their de?ections as the force is applied and 70
The tensioning element E (FIGS. 3 and 6) consists of
a piece of very ?exible sheet material, for example cop
per-beryllium alloy of the order of 0.006 inch in thick~
ness, of generally rectangular shape having a large elon
to render determinate and invarying the point of appli
generally parallel arms 9 connected at their ends by trans
verse web portions 11 and 12 (FIG. 6). The left-hand
cation of the operating force to the arms of the tensioning
gate central opening thereby de?ning a pair of spaced,
3
4
web portion 11 has an opening therethrough for the
screw '7; and underlies the end of the abutment 5 furthest
from the compression spring, and is thereby clamped to
the base 1. The right-hand web portions 12 carries a
movable contact 13 interposed between the ?xed con
compression spring, a tensioning element comprising a
tracts 2 and 3.
A hinge means 14 for receiving the mov
pair of narrow, generally parallel arms connected at their
ends by transverse webs, means ?xing one of said webs
to said base, hinge means connecting that end of the
tensioning element which is remote from the ?xed web
to the free end of the compression spring, a movable
‘able end of the compression spring 6, is also carried by
contact interposed between said ?xed contacts, means for
the right-hand web 11 at a point spaced from the con
transmitting motion from the free end of the compression
tact 13.
spring to said movable contact, and an actuating pin, in
Intermediate the ends of the tension element 8, but 10 combination, means operative to distribute operative
nearer to clamped web 11 than to the hinge means 14,
force, applied to the actuating pin, equally bett can the
each arm 9 has an integral downwardly directed elon
arms of the tensioning element without regard to their
‘gate ?ange 15 at right angles to the arm proper, these
?anges stiffening that part of the tensioning element to
relative vertical disposition.
which the operating force is applied.
tributing operative force equally between the arms of
the tensioning element comprises a rigid balancing ele
The cover 16 of the switch has a cylindrical guide
2. A switch as in claim 1 wherein the means for dis
bore for the actuating pin 13. The axis of the actuating
pin is substantially vertical. Desirably the lower end of
the guide here is ?ared and the head 13a of the pin is
correspondingly beveled, so that in the idle position the
head of the pin occupies but little space within the casing
ment which is freely tiltable about an axis parallel to
and is not cramped between the inner surface of the cas
axis.
the length of the tensioning element, and wherein the
lower end of the actuating pin contacts the balancing ele
ment at a point intermediate the lateral edges of the latter,
and the actuating pin is free to rotate around its own
ing and the balancing element upon which it rests. The
3. A switch as in claim 1 wherein the means for dis
convex head 18a of the pin 18 bears freely and pivotally
tributing operative force equally between the arms of the
upon the transverse balancing element 19 (FIG. 5) which ' tensioning element comprises a rigid balancing element
in turn rests upon dimples 2i} (FIGS. 6 and 8) struck up
which is freely tiltable about an axis parallel to the length
from the arms % of the tensioning element E.
of the tensioning element, and wherein the arms of the
While in the preferred embodiment depicted, the up
tcnsioning element have upstanding projections upon
standing dimples Ztl on the arms 9 of the tensioning ele
which the balancing element bears.
‘ '
ment are shown as being directly opposite one another, 30
4. A switch as in claim 3 wherein the means for dis
it is to be understood that they may be shifted laterally
tributing operative ‘force equally between the arms of the
with respect to each other or to the operating pin so as
to compensate for any otherwise unbalanced forces exist
ing in the switch without departing from the essential
spirit of the present invention.
The transverse balanc~
ing or force-distributing element 19, as here illustrated
comprises a generally triangularly shaped, rigid, ?at piece
of dielectric material, one corner of which has an open
ing through which loosely passes a screw 21 (FIGS. 2
and 3) by which the element 19 is connected to the base
1 of the switch. The same screw 21 also secures the
cover 16 to the base.
tensioning element comprises a rigid balancing element
which is freely tiltable about an axis parallel to the length
of the tensioning element, and wherein the upstanding
projections on the ‘arms of the tensioning elements are
dimples struck up from the material of the tensioning ele
ment and integral therewith.
5. A switch as in claim 3 wherein the means for dis
tributing operative force equally between the arms of the
tensioning element comprises a rigid balancing element
which is freely tiltable about an axis parallel to the length
of the tensioning element, and wherein the balancing ele
As suggested in FIG. 9, the attachment of the trans
ment is connected to the base only and is free to move
verse balancing element 19 to the base 1 is loose enough
relatively to the base except as restrained laterally .by the
to allow said element to tilt freely in the transverse di 45 side walls of the cover and vertically by the actuating pin
rection, that is to sa‘ , about an axis which is parallel to
the length of the tensioning element, thereby to adapt
above and the arms of the tensioning element below.
6. A switch as in claim 3 wherein the means for dis
itself to any ditference in the relative heights of the arms
tributing operative kforce equally between the arms the
? of the tensioning element, whereby force, applied to
tensioning
element comprises a rigid balancing element
50
the actuating pin 18, will be distributed equally and simul~
which is freely tiltable about an axis parallel to the length
taneously to both of the arms 7.
'
of the tensioning element, and wherein the balancing ele
The transverse balancing element 19 is restrained from
ment
comprises a flat piece of insulating material'iof a
moving unduly, in the lateral direction, by the side walls
generally triangular shape and has an aperture near one
22 of the cover 16.
In the modi?cation shown in FIG. 4 the hole in the 55
cover for the reception of the operating pin 26a is made
corner, and a screw, passing loosely through said aper-v
ture, connects the balancing element to the base, said
screw fastening the cover to the base.
7. A snap action electrical switch of the kind which
comprises a base, a compression spring, a normally ?xed
made to the “right” and “left-hand” ends of the switch
base and of certain parts ‘of the switch, but it is to be 60 abutment for one end of the compression spring,'a ten
understood that these terms are only used with reference
sioning element comprising a pair of narrow, generally
to the accompanying drawing and are not to be consid
parallel arms connected at their ends 'by transverse webs,
ered as in any way limiting the position in which the
means ?xing one of said webs to said base, hinge means
switch may be used.
connecting that end of the tensioning element, which is
It should also be understood that this disclosure is for 65 remote from the ?xed web, to the free end of the com
the purpose of illustration only and that this invention
pression spring, and an actuating pin, in combination,
airtight by a ?exible seal '27.
For convenience in description reference has been
includes all modi?cations andequivalents which fall with
means operative to distribute operative force, applied to
in the scope of the appended claims.
the actuating pin, equally between the arms of the tension
I claim:
70 ing element without regard to their relative dispositions,
1. In a snap action electrical switch of the kind which
the tensioning element having integral, transversely spac
comprises a rigid base and a removable cover, both of
ed, upstanding projections to which actuating force is
insulating material, opposed vertically spaced ?xed con
applied by the distributing means.
tacts adjacent to one end of the base, a compression
8. A snap action electrical switch of the kind which
spring, a normally ?xed abutment for one end of the 75 comprises a compression spring, the movable end of
3,019,312
6
which is constrained by a tensioning element comprising
two narrow, generally parallel arms joined at their ends
by transverse webs, said tensioning element being ar
ranged so that the switch will snap when a force is ap
plied to both of said arms, and an actuating pin, char
acterized in having an upstanding integral projection on
each of said arms, and means operative to distribute 0p
erative force, applied to the actuating pin, equally between
said upstanding projections regardless of the relative ver
tical disposition of said arms.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,511,526
2,614,189
2,729,715
2,769,048
2,854,540
Bugge _______________ .. June
Mosley ______________ __ Oct.
Broch ______________ __ Jan.
Harrold ______________ __ Oct.
Cunningham ________ __ Sept.
13,
14,
3,
30,
1950
1952
1956
1956
30, 1958
FOREIGN PATENTS
122,338
Sweden ______________ __ July 27, 1948
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