U.S. patent number 3,790,727 [Application Number 05/314,609] was granted by the patent office on 1974-02-05 for inertia switch with resilient conductive support arm immersed in silicone base viscous fluid medium.
This patent grant is currently assigned to Sealectro Corporation. Invention is credited to Harvey Feinman, Stephen G. Glatzer, Gregory L. Laserson, Rocco Scappatura, Mille Stand.
United States Patent |
3,790,727 |
Laserson , et al. |
February 5, 1974 |
INERTIA SWITCH WITH RESILIENT CONDUCTIVE SUPPORT ARM IMMERSED IN
SILICONE BASE VISCOUS FLUID MEDIUM
Abstract
A force actuated electrical switch which discriminates between
forces having varying time duration. A pendulum, including a
conductive wire secured at one end and fastened to a conductive bob
at the other end. The pendulum is enclosed in a cylindrical
insulator containing a thick viscous fluid. At the lower end of the
cylinder a metal ring is positioned adjacent to the bob and
surrounding it. Under normal conditions the bob remains at the
center of the ring and there is no contact. When the cylinder is
moved in a horizontal direction for an extended time interval,
contact is made between the bob and the ring and the switch is
closed.
Inventors: |
Laserson; Gregory L.
(Scarsdale, NY), Feinman; Harvey (Bronx, NY), Stand;
Mille (New York, NY), Glatzer; Stephen G. (New Rochelle,
NY), Scappatura; Rocco (Mount Vernon, NY) |
Assignee: |
Sealectro Corporation
(Mamaroneck, NY)
|
Family
ID: |
23220643 |
Appl.
No.: |
05/314,609 |
Filed: |
December 13, 1972 |
Current U.S.
Class: |
200/61.49;
200/61.51 |
Current CPC
Class: |
H01H
35/02 (20130101) |
Current International
Class: |
H01H
35/02 (20060101); H01h 035/02 () |
Field of
Search: |
;200/61.48,61.52 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Scott; James R.
Attorney, Agent or Firm: Heilman; James M. Heilman; William
O.
Claims
The embodiments of the invention in which an exclusive property
or
1. An inertia actuated electrical switch comprising; a hollow
cylindrical insulative container for supporting all the switch
components; a pendulum including a conductive suspension and a
metal bob, the suspension secured to one end of the container and
forming one of the switch terminals, the bob formed with an annular
knife edge and normally in axial alignment with the cylinder; an
annular contact ring also mounted in the container adjacent to the
bob and having a serrated inwardly extending surface for contact by
the knife edge of the bob when the switch is actuated; a quantity
of viscous fluid positioned in the container and covering the
pendulum bob and the contact ring; and a stoppered conductive tube
being disposed within the container and connected to the contact
ring for filling the container with fluid, said conductive tube
forming the other
2. A switch according to claim 1 wherein the container is made of
plastic.
3. A switch according to claim 1 wherein the suspension is secured
to the
4. A switch according to claim 1 wherein the serrated contact ring
is part of a tubular insert, force-fitted into the lower portion of
the container.
5. A switch according to claim 1 wherein the suspension is made
of
6. A switch according to claim 1 wherein the conductive tube is
closed by a
7. A switch according to claim 1 wherein the viscous fluid is a
fluid
8. A switch according to claim 7 wherein the viscous fluid consists
of three types of silicone fluid, neither of which comprises more
than 50
9. A switch according to claim 7 wherein the viscous fluid consists
of two types of silicone fluid, neither of which comprises more
than 65 percent
10. A switch according to claim 1 wherein the viscous fluid
consists of two types of silicone fluid and bromo-fluoro-carbon
oil.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to inertia or tilt switches which
are not actuated or closed when at rest or when acted upon by
forces of short duration. Continuous forces alternating in
direction at a frequency above a predetermined rate will also fail
to close the switch. The switch is closed only by a continuous
force acting in a single direction for a stated time interval.
A pendulum type arrangement is used having a conductive wire
suspension and a pendulum bob as one of the switch terminals. A
spaced ring within an enclosing hollow cylinder is the other
terminal. A thick viscous fluid covers the bob and the ring and
slows the action of the bob to prevent contact and closure of the
switch for a designed time interval after the application of a
closing force.
Pendulum type contact switches are well known in the art but they
have been used without the addition of a viscous fluid and they
have responded to vibrational forces having a frequency which is
too high to make the switch available as an alarm signal on a
moving vehicle.
One of the features of the invention is the combination of a heavy
pendulum bob to provide inertia and a thick fluid of high viscosity
surrounding the bob to provide mechanical resistance to the
switch.
Another feature of the invention is the ability of the switch to be
operated by any low frequency force providing the force has a
component which is perpendicular to the longitudinal axis of the
pendulum.
Another feature of the invention is the ability of the switch to
maintain its specified performance characteristics over a wide
temperature range and at all values of air pressure.
The inertia switch comprises a cylindrical insulator, closed at its
lower end by a conductive cup which acts as one of the switch
terminals. A pendulum is positioned in axial alignment with the
cylinder and comprises a conductive wire, secured to the top end of
the cylinder, and a metal bob at the lower end of the wire so that
the bob normally is concentric with the brim of the cup. A viscous
fluid fills the cup.
Other features and additional details of the invention will be
disclosed in the following description, taken in connection with
the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a cross sectional view of the inertia switch showing the
bob in its axial or normal position.
FIG. 2 is a cross sectional view similar to FIG. 1 but showing the
bob in contact with the ring and a fluid in the cylinder.
FIG. 3 is a cross sectional view of the bob.
FIG. 4 is a top view of the inertia switch.
FIG. 5 is a cross sectional view, to an enlarged scale, of the
switch shown in FIG. 1 and is taken along line 5--5 of that
figure.
FIG. 6 is a cross sectional view, also to an enlarged scale, of the
closed switch shown in FIG. 1 and is taken along line 6--6 of that
figure.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the figures, the switch comprises an outer
cylinder 10 made of insulator material preferably Delrin, a
polyacetal resin of formaldehyde. Other insulating materials may be
used provided they are good insulators and have the required
mechanical strength. The cylinder 10 has an integral top closure
disk 11 formed with a small hole 12 in the axial position. The
remainder of the cylinder 10 is hollow, having a smooth inner
surface 13. A suspension wire 14 is positioned in hole 12 and is
sealed in position by a small amount of plastic 15. The end of wire
14 which extends above the cylinder is used as one terminal of the
switch.
A heavy metal bob 16 is fastened to the lower end of the suspension
wire 14. The wire 14 is pushed into a central hole and soldered in
place by a small drop of solder 17. The bob is generally
cylindrical but there is an annular sharp ridge or knife edge 18
formed near its lower end. The bottom portion is cone shaped. The
knife edge 18 makes the electrical contact which closes the
switch.
A hollow cylindrical plug 20 forms the second terminal of the
switch. It is force-fitted into the lower portion of cylinder 10
and is fitted to a metal plug 21 which includes a disk 22, a tube
23, and a flanged terminal 24. An inwardly extending rim 25 is
formed opposite the knife edge 18, and its inner face is serrated
by the formation of a plurality of saw-toothed edges. The edges
make contact with the knife edge 18 on the bob 16 to make the
contact. The two edged portions positively cut through the film of
the heavy fluid in the cylinder and assure a firm conductive
contact whenever the bob is forced against the rim 25.
The switch is assembled by first placing the bob 16 and its
suspension wire 14 in position and adding the plastic cement 15.
Then the plug assembly 20, 21 is pressed into place. The switch is
next turned upside down, and a viscous fluid 26 is poured into the
switch through the hollow tube 23. When filled, the switch is
stoppered by the addition of a cork 27 of self-setting plastic
material (see FIG. 2). The switch is now ready for use, tube 23 or
flange 24 serving as the second electrical terminal.
A sustained motion in any horizontal direction will not close the
switch. It is necessary to apply a sustained force which will
result in a steady acceleration or steady increase in velocity to
move the bob 16 through the viscous fluid and establish electrical
contact. A sustained deceleration or steady decrease in velocity
will give the same results. The switching action may be varied over
a wide range by cnanging the composition of the fluid which
surrounds the bob 16. The fluid used must have certain basic
characteristics such as: small temperature coefficient of
viscosity; be non-corrosive; and chemically stable. Two or more
fluids may be mixed to obtain the desired viscosity value, provided
they are compatible and operate in a single phase over the required
temperature range. Many materials are available from which to
choose, such as halogenated hydrocarbons, silicones, and solutions
of polymers. Three satisfactory mixtures are shown below;
percentages in volume.
EXAMPLE I
Silicone Fluid SF-96-200 18. % Silicone Fluid SF-96-350 50. %
Silicone Fluid DC-210-1000 32. % EXAMPLE II Silicone Fluid
DC-200-100 41.6 % Silicone Fluid DC-210-1000 57.4 %
Bromo-Fluorocarbon Oil 1.0 %
EXAMPLE III
Silicone Fluid SF-96-200 36. % Silicone Fluid DC-210-1000 64. %
The above described switch has been found useful as a safety device
in all types of moving vehicles and can be used as a signalling
device on an airplane when the vehicle crashes, sending out a
distress signal which can aid in locating the wrecked plane.
* * * * *