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Jan. '7, 1947.
C. E. MILLER
2,413,882
. ACTUATOR
Filed Oct. 50. 1944
INVENTOR.
CHARLES E. MULLER
‘2,413,882
Patented Jan. 7, 1947
UNITED STATES PATENT OFFICE
2,413,882
ACTUATOR
Charles E. Miller, Pasadena, Calif., assignor to
Bendix Aviation Corporation, South Bend, Ind,
a corporation of Delaware
Application October 30, 1944, Serial No. 561,141
2 Claims. (Cl. 264-15)
2
1
in the switch mechanism. It is preferable in
such devices that the actuator mechanism be
completely out of contact with the control switch
when the actuator is rotating, to eliminate any
friction between the parts.
In the drawing:
This invention relates to centrifugal actua
tors such as may be employed on motor shafts
to open or close switches in response to rotation
of the shaft above a certain speed.
An object of the invention is to provide a par
ticularly simple, inexpensive, and reliable actu
ator of the type referred to.
Fig. 1 is a view showing an actuator in ac
cordance with the invention mounted on the end
of a motor shaft for actuating the plunger of a
Another object is to provide an actuator the
parts of which can be very easily and quickly
assembled and disassembled.
>
10
switch;
Fig. 2 is a view of the actuator similar to the
Still another object is to provide a centrifu
View of Fig. 1, but showing the position of the
gal actuator which is substantially immune to in
actuator when rotating.
jury or damage by rotation at excessive speeds.
Fig. 3 is a cross section taken substantially in
Other more speci?c objects and features of
the invention will appear from the detailed de 15 the plane III—III of Fig. 1; and
Fig. 4 is a detail section taken in the section
scription to follow of a particular embodiment of
IV-IV of Fig. .3.
the invention.
Referring first to Fig. 1, there is shown a mo
Brie?y, the invention comprises, in its pre
tor In, of any desired construction, having a
ferred form, an open-ended cup-shaped body or
frame mounted on the end of the shaft to be 20 shaft H on the outer end of which is mounted
an actuator 12 in accordance with the present
rotated, and containing an axial shiftable pin
invention, for actuating the plunger l3 of a‘
which is adapted to engage the switch plunger
switch 14.
or other member to be actuated. When the cup
The actuator l2 comprises a tubular body, or
is not rotating, the pin is maintained in an outer,
or projected position, by a spring. Adjacent its . frame, I5 having a central bore iii therein. The
rear end of this bore [6 receives the outer end
open end, the cup-shaped frame has diametrically
of the motor shaft II, and the body l5 may be
opposite slots that extend radially and longitudi
secured to the shaft for rotation therewith by a
nally and guide a pair of bellcrank levers, the
pin H.
levers being fulcrumed on, a spring wire ring
The bore l6 extends forwardly for a substan
which is expanded into an annular groove in the tial distance beyond the end of the motor shaft
inner surface of the cup-shaped frame. Each
II and serves as a guide for a plunger or pin IB
bellcrank lever has a long arm extending sub
having a head I9 on its outer or front end. A
stantially parallel to the axis of rotation and a
helical compression spring 20 surrounds the pin
short arm extending radially inwardly into con
l8 and is compressed between the body member
tact with the front end of the axially shiftable
and the head I9 of the pin, to constantly urge
pin, to oppose the force of the spring. When the
the latter axially to the right out of the bore
device is at rest, there are no centrifugal forces
l6. Outward movement of the pin [8 by the
involved, and the spring maintains the pin in
spring 20 is limited by a plurality of bellcrank
an outer position in which the long arms of the
lever elements 22 which are guided for move
levers are approximately parallel to the shaft
ment in radial slots l5a provided therefor in the
and are largely contained within the slots in the
frame l5. Each lever element 22 has a long
frame. However, when the shaft bearing the
arm 23 extending substantially parallel to the
actuator is rapidly rotated, the centrifugal force
axis of the body 15, and a short arm 24, which is
developed in the long arms of the levers swings
substantially normal to the long arm 23 and ex
them outwardly about their fulcrums, and the
short arms of the levers force the axially shift- "
able pin inwardly, overcoming the force of the
spring. The device is most commonly used to
tends inwardly into engagement with the front
face of the head l9 of pin 18.
All of the lever elements 22 are fulcrumed on
a spring wire ring 25 which is positioned in an
actuate a controlled element of a switch, which
controlled element is in contact with the end of 50 annular groove 26 formed within the skirt por
the axially movable pin and, is depressed by the
pin when the actuator is stationary. When the
actuator rotates at su?icient speed, the pin there
in is retracted by the levers, permitting the
plunger of the switch to be ejected by a spring 55
tion of the body l5, each lever element having
an aperture 21 for receiving the wire 25. As best
shown in Figs. 3 and 4, the wire ring 25 is not
continuous but is split and originally shaped to
a larger diameter than the groove 26 in which it
2,413,882
3
4
is mounted, so that it can ‘be readily assembled
and expands into the groove. The resilience of
amples of changes that can be made, more than
two levers 22 may be employed where greater
force is required. It is desirable, however, in
order to produce'a balanced structure, that the
lever arms be symmetrically positioned about the
axis of rotation.
I claim:
1. A centrifugal actuator of the type described
the wire ring always maintains it in position
within the groove because all forces applied to
the ring by the lever elements act either out
wardly or longitudinally, never inwardly. One
end of the ring is preferably turned in as indi
cated at 28 to prevent the ring from shifting in
the groove and releasing the lever elements, al
though in use there‘ is little or no tendency for
comprising: a tubular frame member supported
for rotation about its axis and adapted to be ro
the ring to shift.
tated; a controlled element axially aligned with
The device can be very readily assembled and 7 said axis and supported for axial movement with
disassembled by virtue of the fulcrum structure
respect to said frame member; spring means urg
involving the ring 25 in the groove 26. Thus, the
ing said controlled member axially in one direc
procedure for assembling the parts of the actu 1.5 tion with respect to said frame member; a plu
ator together is to ?rst place the helical com
rality of bellcrank lever elements fulcrumed to
pression spring 26 about the pin “3 and insert
said frame member for movement in radial
the latter in the bore 5 8 far enough to fully com
planes, each lever element having a ?rst arm
press the spring. Thereafter, the lever elements
normally extending approximately parallel to
22 are threaded on to the fulcrum ring 25, and 20 said axis and a second arm approximately normal
the levers and ring are assembled on the body
to the ?rst arm and extending inwardly into en
22 by sliding the long arms 23 of the lever ele
gagement with said controlled element for mov
ments longitudinally into the radial slots in the
ing the latter against the force of said spring
body while at the same time squeezing the ring
means in response to outward movement of said
25 radially (with the ends of the ring in over 25 first arm; said tubular frame member compris
lapping relation) to enter the ring into the open
ing an annular skirt surrounding said controlled
end of the skirt of the body. As soon as the ring
element and said skirt having an annular groove
in its inner surface and having radial longitudinal
slots intersecting said annular groove for slid
has been entered into the ‘skirt, it is retained
against expansion by the skirt; the ring and the
lever elements are then pressed axially until the
ring vreaches the groove 26 and snaps into it.
Thereafter, the pin I8 will be prevented from
escaping from the bore l6 by engagement of the
head of the pin against the short arms 243 of th
and a ring in said groove and extending through
said bearing holes in said lever elements for rule
crumil'lg said lever elements on said frame
lever elements.
member.
'
ably receiving said lever elements; said lever ele
ments having transverse bearing holes therein;
-
As shown in Fig. 1, the plunger I3 of the switch
Ill is engaged by the head I 9 of pin 13 and slightly
depressed thereby, in which position the contacts
2. A centrifugal actuator of the type described
comprising: a tubular frame member supported
for rotation about its axis and adapted to be ro
of the switch M will be either open or closed
tated; a controlled element axially aligned with
according to thedesign of the switch. However, 40 said axis and supported for axial movement With
when the actuator is rotated above a predeter
respect to said frame member; spring means urg
mined speed, the centrifugal force developed in
ing said controlled member axially in one direc
the long arms 23 of the levers 22 throws them
tion with respect to said frame member; a plu
outwardly as shown in Fig. 2, in which position
rality of bellcrank lever elements fulcrumed to
the short arms 21% of the lever element's depress
said frame member for movement in radial
the pin l8, permitting the plunger iii of the
planes, each lever element having a ?rst arm nor
switch to be lifted by a spring (not shown) With
mally extending approximately parallel to said
in the switch It and close or open the contacts
axis and a second arm approximately normal to
within the switch, depending upon the construc
the ?rst arm and extending inwardly into engage
tion of the latter. Switches of the type shown are
ment with said controlled element for moving
old and well-known and do not constitute a part
the latter against the force of said spring means
of the present invention. Preferably, the move
in response to outward movement of said ?rst
ment of the pin l8 by the lever elements 22 is
arm; said tubular frame member comprising an
sufficient to disengage the head It of the pin
annular skirt surrounding said controlled element
from the vswitch plunger i3 so that there ‘is no
and said skirt having an annular groove in its
friction therebetween during rotation of the ac 55 inner surface and having radial longitudinal slots
tuator, after the motor has come up to speed.
intersecting said annular groove for slidably re
As shown in Fig. 2, depression of the pin i8
ceiving said lever elements; said lever elements
and outward movement of the long arms 23 of
having transverse bearing holes therein; and a
the lever elements is limited by contact between
split spring wire ring positioned in said groove
the end of the neck 39 of the body at the outer 60 and extending through said bearing holes in said
end of bore it and the head it.
lever ‘elements for fulcruming said lever elements
‘Various departures from the exact construction
on-said frame member; said ring being originally
shown can be made without departing from the
of larger diameter than said annular groove
invention which is to be limited only to the ex
whereby it is resiliently retained in said ‘groove.
tent set forth in the appended claims. As ex 65
CHARLES E. 'MILLER.
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