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Патент USA US2409474

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Oct. 15, 194e.
w. L.' BUTLER
2,409,472
ELECTRIC SWITCH
Filed May 2.9, 1943
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William
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Inventor:
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Oct. 15, 1946.
w41.. BUTLER _
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2,409,472
ELECTRIG swITcH
Inventor:
Wìliiam Lawrence Butler;
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t# His.
2,409,472
Patented Oct. 15, 1946
UNlTED STATES PATENT OFFICE
2,409,472
ELECTRIC SWITCH
William Lawrence Butler, Schenectady, N. Y., as
signor to General Electric Company, a corpora
tion of New York
Application May 29,A 1943, Serial No. 489,021
8 Claims. (C1. 200'--165)
1
My invention relates to electric switches, more
pariicularly to switches especially designed to
2
ating shaft IE pivotally mounted in the sides of
the casing and carrying interiorly of the casing
closing position when subjected to severe vibra
an actuating cam 22 and exteriorly of the casing
an operating lever I8. rI‘he contact base I3 is
tion or the shock of sudden impact. The inven
preferably formed of molded plastic insulating
tion is particularly applicable to control switches
of relatively small capacity, such as limit
switches, selector switches, and the like.
The principal object of my invention is to Dro
material and is bolted inside the casing I0 at the
maintain a desired circuit-opening or circuit
end opposite the operating shaft I6.
Referring first to the switch operating mech
anism, the operating shaft I6 is pivotally mount
vide a new and improved simple, dependable and 10 ed in a pair of bearing'bosses i9 and 29 formed
inexpensive electric switch of the shock-proof
ype.
It is a further object of my invention to pro
'in opposite walls of the casing IE). The shaft I6
extends through one wall of the casing and car
ries on its outer end the operating lever I8 upon
the end of which is mounted a roller 2| for en
vide a switch contact structure arranged to min
imize contact bouncing upon subjection to severe 15 gagement with any movable member whose mo
tion it is desired to limit. Interiorly of the cas
vibration or impact shock.
ing ID and between the upright pillars I5 and
It is a still further object of my invention to
I5@ the operating shaft I6 has centrally connect
provide a switch contact structure arranged to
ed thereto the operating cam 22 upon opposite
minimize relative sliding movement of the con
sides of which is positioned a pair of helical
tacts upon vibration thereof in engaging position.
springs 23 and 24 surrounding the shaft I6. Ad
It is still another object of my invention to pro
jacent the bearing bosses I 9 and 20 and in spaced
vide an electric switch contact structure arranged
relation to the operating cam 22, the shaft I6
to minimize local Contact Vibration in response
has connected thereto a pair of stop members 25,
to impact shock.
rline new and novel features of my invention 25 26 formed to provide axially extending projec
tions 2l' and 28. respectively, preferably molded
or cast integrally therewith, The stop members
25 and 255 are also provided with separate pairs
complete understanding of the invention and a
of radially spaced peripheral bosses 29 and 30,
further appreciation of its objects and advan
tages, reference should now he had to the follow 30 respectively. The bosses 29 and 30 are arranged
for engagement. respectively, with narrow web
ing detailed description taken in conjunction with
portions 3l and 32 formed integrally with the cas
the accompanying drawings in which Fig. 1 is a
ing ID and extending between the bearing bosses
plan view oi an electric switch embodying my in
I9 and 20 and the pillars I5 and IECL, respectively.
vention, the cover being partly broken away to
The peripheral bosses 29 and 30 are positioned
illustrate the switch structure; Fig. 2 is a cross
to engage the webs 3! and 32 to limit rotational
sectional view taken along the line 2_2 of Fig.
movement of the operating shaft I6 and the cam
l; Fig. 3 is a cross-sectional view taken along the
22. The helical springs 23 and 24 are each nro~
line 3-3 of Fig. l; Fig. 4 is an exploded perspec
vided with angularly spaced radially extending
tive View of certain parts of the switch operating
end portions embracing the projections 21 and
mechanism; Fig. 5 is an end elevation of the
2S, respectively.
switch contact assembly; and Figs. 6 and 'I are
Referring now more particularly to Figs. 2 and
detailed views of certain portions of the switch
6, it will be observed that the actuating lever I4
actuating mechanism.
is formed of a pair of parallel plates connected
Referring now to the drawings, I have shown
in parallel spaced relation having forked end
my invention by way of illustration as applied to
will be pointed out with particularity in the
claims appended to this specification. For a more
an electric limit switch mounted in a casing I0
having a cooperating cover II. To render the
switch weatherproof, the cover II is preferably
bolted to the casing and a gasket I2, of rubbery
or the like material, is provided therebetween.
In general, the switch comprises a contact as.
scmbly mounted upon a suitable base I3, a switch
actuating arm It pivotally mounted upon a pair
of upright bosses or pillars I5 and |509 integrally
formed interiorly of the casing I0, and an oper
portions 35 and 36 mounted upon a transverse
pivot pin 'ell'.
The forked end portions of the
plates 35 and` 36 carry therebetween a pair of
cam follower rollers 38 and 39 arranged for en
gagement with angularly spaced peripheral por
tions of the operating cam 22.
A helical com--
-pression spring Ita positioned between the pillars
I5 and Iâa engages at one end the casing I0 and
at the other end the forked end of the actuating
lever I4, thereby to bias the roller 38 into con
2,409,472
3
tinuous following engagement with the surface
of the cam 22. The earn 32 is formed with a pe
ripheral depression 2id adjacent the roller 38
when the cam 22 and operating shaft I5 are in
4
and 5S are formed integrally with the spring
strips 49 and 48, respectively, and extend later
ally and in parallel spaced relation therefrom
in the region of the switch contacts.
their mid-positions normally maintained by the
By reason of the manner of mounting the can
helical springs 23 and 24, In this position a pe
ripheral projection 22D on the cam 22 lies under,
but does not normally engage, the roller 39. The
projection 22h is not necessary to normal switch
operation, but has for its purpose the limitation
of movement of the actuating lever I4 due to vi
bration or impact. The projection 22h is so ar
tilever spring strips 48 and 49 described above,
and because of the design of the spring strips
themselves, their tendency to bounce open or to
slide upon each other when subjected to vibra
tion or shock in engaging position is substan
tially eliminated. As described above, each pair
oi spring strips extends in proximate parallel
ranged that, without rotation of the shaft I6, the
spaced relation through a relatively narrow slot
in the upper side of the base I3. The ñxed ends
depression 22a to open the switch contacts.
15 of each pair of cantilever springs are therefore
The actuating lever I4 is pivotally mounted
mounted upon the base in closely spaced relation
upon the internal pillars I5 and I5a by means of
with respect to the length of the spring strips.
the transverse pin 3l, the opposite ends of which
This brings the theoretical points oi fiexure of
are seated in transverse slots 48 formed in the
the springs very close together. rl‘he cantilever
upper ends of the pillars. The slots 40 are pro 20 springs and the associated switch contacts, be
vided with cover plates 4I and 47. which serve
ing of substantially the same physical propor
both to hold the transverse pivot pin 31 in op
tion, tend to move sideways at substantially the
roller 3B cannot move suiiiciently far out of the
erating position in the slots 40 and to provide
same speed in response to vibration or shock.
fixed stops for the helical springs 23 and 24. As
Since the points of flexure of the springs are very
may be best observed by reference to Figs. 1 and 25 close together, the free ends of the springs swing
2, the cover plates 4| and 42 are each slotted
from substantially the same point so that there
longitudinally to provide a pair of up-turned
is very little, if any, sliding movement between
spring stops 43 and 44 of unequal length engag
the contacts. It has been found that this tend
ing opposite extending ends of the helical springs
ency of the contacts to move together at sub
23 and 24. The stop plate 4I cooperates with .30 stantially the same speed thereby to avoid bounc
the spring 23 and the stop plate 42 cooperates with
ing of the contacts under vibration or shock is
the spring 24, the stçps 43 and 44 upon each
greatly enhanced by spacing apart the theoreti
plate engaging adjacent sides of the angularly
cal points of flexure at the fixed ends of the
spaced extending ends of the associated spring.
springs by substantially the same distance as the
The actuating lever I4 has connected to each 35 centers oi’ gravity of the springs and connected
plate 35 and 36, opposite the forked roller carry
contacts. With such spacing a shock in any di
ing end thereof, a wedge-shaped cam member
rection will produce a turning in the same direc
45. As best illustrated at Figs. 2 and 6, the cam
tion in both contact springs, thereby to produce
members 45 are shown as blocks of molded in
following rather than separating movement o_f
sulating material bolted to the actuating lever 40 the contacts. If the points of flexure were spaced
I4 and arranged for reversal in a manner here
apart substantially farther than the centers oi
inafter to be described, to select either a nor
gravity, an impact along a line between the cen
mally open or a normally closed position of the
ters of gravity would produce opposite turning
associated contacts.
movements thereby to open the contacts.
Referring now to the contact assembly, it will
To further reduce the tendency of the contacts
be observed that the insulating contact base I 3
to bounce apart under shock, the contact closing
is of substantially box-like form and is slotted
bias of each spring strip is sufliciently strong to
on its upper side at 45 and 41 to provide for the
permit it to follow its mate to the limit oi its
suspension therein of a corresponding number of
movement. In this connection, it will be noted
pairs of contact elements. Each contact assem 50 that each pair of spring contacts is positioned in
bly comprises a pair of cantilever spring strips
recess between the side walls and a central
48, 49. Each contact spring has an outturned
boss 69 of the contact base I3. The boss 6I) and
ear at its base end bolted to the top side of the
the side walls of the base provide stops 6I and
base and to an associated terminal block 5B or
E2 for limiting lateral movement of the spring
5I,‘as shown at Fig. l. Each pair of spring strips 55 strips. If, under shock or vibration, either strip
extends through one of the slots 46, 4'I in proxi
of a pair of contact strips is moved against its
mate parallel spaced relation and preferably has
bias and into engagement with the associated
positioned between the fixed ends of the strips an
stop, the closing bias of the cooperating spring
insulating spacer 52.
strip is sufficient to permit it to follow the iirst
The cooperating cantilever spring strips 48 and 60 strip to the limit of its movement, thereby to
49 carry at their free ends a pair of cooperating
maintain the contacts closed. The contact stops
switch contacts 53, and 54, and are formed to
SI and 62 formed upon the base I3 and the boss
provide adjacent the contacts a pair of juxta
6I) are very close to the center of gravity of the
posed carnming portions 55 and 55 for coopera
associated contact elements, so that only slight
tion with the wedge-shaped cam 45. Preferably, 65 lateral vibrational movement is permitted. By
the spring strips 48 and 43 are tapered toward
this close spacing of the contact stops, twisting
their free ends to reduce the mass and inertia of
motion of the contact springs under shock is
the free ends thereby to reduce their vibration.
prevented, thereby to eliminate local vibrational
The spring strips of each pair are biased toward
forces which may be set up by such twisting.
each other to maintain the cooperating contacts 70
The use of the camming extensions 55 and 56
53 and 54 normally in engagement. The asso
on the free ends of the contact strips for cooper
ciated camming portions 55 and 56 are arranged
ation with the wedge-shaped cams 45 has the
to be slightly spaced apart when the contacts
advantage that, when the contacts are separated
are in engagement. In the illustrative embodi
by insertion of the wedge 45, they move apart
ment of the invention, the camming portions 55 75 With a rolling motion, as distinguished from the
2,409,472
straight-line motion which would result from
insertion of the wedges` directly between the
6
stood that I intend in the appended claims to
cover all such modiñcations as fall within the
true spirit and scope of my invention.
contact suriaces. In the illustrated embodiment
What I claim as new and desire to secure by
or" the invention, this rolling motion results» from
Letters Patent of the United States is:
a twisting of the spring strips 48 and 43 caused
l. An electric switch comprising a base, a pair
by exerting the separating force at only one side
of cantilever spring strips mounted at one end
oí the center lines of the strips. The rolling
upon said base in substantially parallel spaced
separating motion has a desirable tendency to
relation and providing at their free ends coop
discourage arcing upon separation of the
erating switch contact portions and separate
contacts.
juxtaposed camming portions extending laterally
As previously mentioned, any pair of contacts
from said spring strips in parallel spaced relation,
may be arranged to be normally open or normally
said spring strips being biased to maintain said
closed by merely reversing the position of the as~
contact portions in engagement and said cam
sociated wedge-shaped cam 45 with respect .to
the actuating lever I4. Referring particularly -to 15 ming portions in proximate spaced relation, and
switch actuating means comprising a wedge
Fig. 2, it will be observed that, if the cams 45 are
shapedA cam movable from a position of disen
gagement to a position between said camming
in the drawings, the widest portion of the cam
portions only, thereby to separate said contact
will normally fall between» the camming portions
55 and 56 of the associated spring strips, thereby 20 portions with a torsional rolling action.
2. An electric switch comprising a base, a pair
normally to maintain the contacts in open posi
of cantilever spring strips mounted at one end
tion. Aotuating movement of the lever I4 in a
upon said base in substantially parallel spaced
counterclockwise direction about the pivot pin
relation, a pair of cooperating switch contacts
31, as viewed at Fig. 2, would then move the nar
mounted upon the free ends of said spring strips,
row portion of the wedge-shaped cams 45 between
said spring strips being biased to maintain said
the spring extensions 55 and 56 to permit closing
contacts in engagement and being provided at
of the contacts. As illustrated in the drawings,
said free ends with juxtaposed camming portions
both pairs of contacts are normally closed.
V
extending laterally from said strips in parallel
It is believed that from the foregoing detailed
spaced relation, and switch actuating means comdescription of the construction and arrange
prising a wedge-shaped cam movable from a po
ment of the various parts of my switch, its mode
sition of disengagement to a position between said
of operation will be easily understood. Brieiiy,
camming portions only, thereby to separate said
it may be noted that separation of the contacts
contacts with a torsional rolling action.
may be effected by either clockwise or counter
3. An electric switch comprising a base, a pair
clockwise movement of theV operating shaft I6, as
of tapered cantilever spring strips mounted at
viewed at Fig. 2. For example, if the shaft I6
their wider ends upon said base at points proxi
is moved in .the clockwise direction, the spring
mately spaced in relation to the length of said
stops 43 hold one end of each of the helical
spring strips and extending in substantially par
springs 23 and 24 stationary and the projections
21 and 28 on ythe stop members 25 and 25, respec 40 allel spacedV relation, a pair of cooperating switch
contacts mounted upon the narrow free ends of
tively, move the opposite ends of the springs in a
said spring strips, said spring strips being pro
clockwise direction against the spring restraining
vided at said free ends with juxtaposed camming
force. Clockwise movement of the operating
shaft is limited by engagement of the upper pe
portions and being biased to maintain said con
ripheral bosses 29 and 30 on the stop members
tacts in engagement and said camming portions
25 and 26 (as viewed at Fig. 2) with -the webs 3|
in proximate spaced relation, fixed vstop means
and 32, respectively, of the casing HJ. The cam
adjacent said free ends of said spring strips for
limiting contact disengaging lateral movement
22, moving in a clockwise direction with the opu
of each of said spring strips, the spacing between
era-ting shaft I6, moves the roller 38 on the ac-tu
ating lever i4 out of the slot 22a thereby to move
said stop means and the adjacent spring strip
being substantially equal to the spacing between
the actuating lever i4 in a counterclockwise di
said spring strips, and switch actuating means
rection, as viewed at Fig. 2, against the bias of
the spring 14a. Counterclockwise movement of
comprising awedge-shaped cam movable from
the actuating lever I4 moves the wide portions
a position of disengagement to a position between
of the wedges 45 between the camming exten
saidv camming means to separate said contacts.
turned around 180° upon a vertical axis as viewed
sions 55 and 56 of the spring strips to separato
_
the contacts. As soon as'the operating lever I2
is released, the helical biasing springs 23 and 24
return the operating shaft I6 to its normal midñ
position as shown in the drawings.
Upon counterclockwise movement of the opern
ating shaft I6, as viewed at Fig. 2, an entirely
to vibration and impact shock comprising a base,
a pair of cantilever spring strips mounted at .one
end upon said base at points proximately spaced
in relation to the length of said spring strips and
similar action takes place, except that the spring
4. .An electric switch adapted for subjection
extending therefrom in substantially parallel
spaced relation, a pair of cooperating switch con
tacts mounted upon the free end of said spring
Stops 44 serve Ito hold stationary theassociated
ends of the helical springs 23 and 24, while the
projections 21 and 28 move the other ends of the
springs in a counterclockwise direction. Counter~
clockwise movement of the cam 22 also raises the
roller 38 out of Ithe slot 22a and produces counter
clockwise movement of the actuating lever Mi to
strips, said spring strips being provided at said
free ends with juxtaposed camming portion and
separate the contacts.
spring strips, the spacing between said stop
While I have shown only one preferred embodi
ment of myinvention by way of illustration, many
other modifications will occur to those skilled in
the art and I, therefore, wish to have it under 75
means and the adjacent spring strip being sub
stantially equal to the spacing between said
spring strips, the contact engaging bias of each
of said spring strips `being suflicient to permit it
being biased to maintain said contacts in engage
ntent and said camming portions in proximate
spaced relation, fixed stop means adjacent said
.free ends of said spring strips for limiting contact
disengaging lateral movement of each of said
2,409,472
7
8
to maintain following engagement with the co
torsionally to stress said spring strips and to
operating spring strip at least until said cooperat
ing spring strip engages its associated stop means
when subjected to vibration or impact, and
switch actuating means comprising a wedge
separate said contacts with a rolling action.
7. An electric switch comprising a slotted base,
a pair of cooperating switch elements each in
cluding a cantilever spring strip carrying at its
shaped cam movable from a position of disen
free end a switch contact, said pair of spring
gagement to a position between said camming
means to separate said contacts.
5. An electric switch comprising a base, a pair
of cantilever spring strips mounted at one end
upon said base at points proximately spaced in
relation to the length of said spring strips and
strips extending in substantially parallel spaced
relation through a slot in said base and be
ing 'mounted upon said base at points spaced
by substantially the same distance as the centers
of gravity of said switch elements, a pair of
juxtaposed camming extensions projecting later
extending in substantially parallel spaced rela
ally from said spring strips adjacent said con
tion, a pair of cooperating switch contacts
tacts, said spring strips being biased to mainmounted upon the free ends of said spring strips, 15 tain said contacts in engagement and said cam
said spring strips being provided at said free
ming extensions in proximate spaced relation,
ends with juxtaposed camming extensions pro
fixed stop means adjacent said free ends of said
jecting laterally from said strips adjacent said
spring strips for limiting contact separating lat
contacts and being biased to maintain said con
tacts in engagement and said camming exten
sions in proximate spaced relation, fixed stop
eral movement of each of said spring strips, the
20 spacing between said stop means and the ad
means adjacent said free ends of said spring strips
for limiting contact disengaging lateral move
ment of each of said spring strips, the spacing
between said stop means and the associated spring 25
strip being substantially equal to the spacing
between said spring strips, a switch actuating
lever carrying at one end a wedge-shaped cam
movable from a position of disengagement to a
jacent spring strip being substantially equal to
the spacing between said spring strips, and switch
actuating means comprising a Wedge-shaped cam
movable from a position of disengagement to a
position between said camming extensions to sep
arate said contacts.
8. An electric switch comprising a slotted base,
a pair of cooperating switch elements each in
cluding a tapered cantilever spring strip carry
position between said camming means to separate 30 ing at its narrow free end a switch contact, said
said contacts, a forked cam follower mounted
spring strips extending through a slot in said
upon the opposite end of said switch actuating
base in substantially parallel spaced relation and
lever, and a rotatable operating cam disposed in
being mounted at their wider ends upon said base
operative relation with respect to said forked cam
at points spaced by substantially the same dis
follower for actuating said switch actuating lever,
tance as the spacing between the centers of
said forked cam follower providing a pair of
gravity of said switch elements, a pair of juxta
members disposed adjacent angularly spaced
posed camming extensions projecting laterally
points of said operating cam thereby positively
from said free ends of said spring strips, said
to maintain continuous following relation there
spring strips being biased to maintain said con
between.
40 tacts in engagement and said camming exten
6. An electric switch comprising a base, a pair
sions in proximate spaced relation, fixed stop
of cooperating switch elements each including a
means adjacent said free ends of said spring
cantilever spring strip carrying at its free end a
strips for limiting contact separating lateral
switch contact, said spring strips extending from
movement of each of said strips, the spacing be
said base in substantially parallel spaced rela 45 tween said stop means and the adjacent spring
tion and being mounted at points spaced by sub
strip being substantially equal to the spacing
stantially the same distance as the centers of
between said spring strips, the contact engaging
gravity of said switch elements, a pair of juxta
bias of each of said spring strips being surfi
posed camming extensions projecting laterally
cient to permit it to maintain following engage
and in parallel spaced relation from said spring 50 ment with the cooperating spring strip at least
strips adjacent said contacts, said spring strips
until said cooperating spring strip engages the
being biased to maintain said contacts normally
associated stop means, and switch actuating
in engagement and said camming extensions in
means comprising a wedge-shaped cam movable
proximate spaced relation, and switch actuating
from a position of disengagement to a position
means comprising a wedge-shaped cam movable 55 between said camming extensions to separate said
from a position of disengagement to a position
contacts.
between said camming extensions only, thereby
WILLIAM LAWRENCE BUTLER.
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