U.S. patent number 3,649,787 [Application Number 05/063,740] was granted by the patent office on 1972-03-14 for disturbance sensitive switch.
This patent grant is currently assigned to Raytheon Company. Invention is credited to Joseph A. Kasabian.
United States Patent |
3,649,787 |
Kasabian |
March 14, 1972 |
DISTURBANCE SENSITIVE SWITCH
Abstract
A disturbance sensitive device comprising an electrical switch
having resilient means for supporting a movable contact member in
normally open relationship with a stationary contact member, and
structured to provide prolonged closure when the device is
disturbed. A further improvement includes a second resilient means
which is carried on the movable contact member for reducing the gap
between the contacting members and increasing the closure time
interval.
Inventors: |
Kasabian; Joseph A.
(Newtonville, MA) |
Assignee: |
Raytheon Company (Lexington,
MA)
|
Family
ID: |
22051179 |
Appl.
No.: |
05/063,740 |
Filed: |
August 14, 1970 |
Current U.S.
Class: |
200/61.45R;
200/80R; 340/683; 340/566 |
Current CPC
Class: |
H01H
35/144 (20130101) |
Current International
Class: |
H01H
35/14 (20060101); H01h 035/14 () |
Field of
Search: |
;200/61.45-61.53,8R
;340/261,262 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schaefer; Robert K.
Assistant Examiner: Ginsburg; M.
Claims
I claim:
1. A disturbance sensitive switch comprising:
a stationary conductor and a movable conductor disposed in
operative relationship with one another; and
resilient means secured to the movable conductor for entirely
supporting the movable conductor and having orthogonally directed
helical and spiral components with respect to the stationary
conductor for maintaining the movable conductor in operative spaced
balanced relationship with the stationary conductor independently
of the orientation in any direction of the switch in the static
state.
2. A disturbance sensitive switch as set forth in claim 1 wherein
the movable conductor is hollow and disposed in encircling
relationship with the movable conductor, the helical component is
disposed in coaxial relationship with the stationary conductor and
the spiral component comprises continuous filamentary turns having
progressively decreasing radii and extending radially inward from
the helical component toward the stationary conductor.
3. A disturbance sensitive switch as set forth in claim 1 wherein
the stationary conductor is hollow and disposed in encircling
relationship with the movable conductor, the helical component is
disposed in coaxial relationship with the stationary conductor and
the spiral component comprises continuous filamentary turns having
progressively increasing radii and extending radially outward from
the helical component toward the stationary conductor.
4. A disturbance sensitive switch comprising:
an elongated stationary conductor;
a cylindrical conductor disposed in normally spaced coaxial
relationship with the stationary conductor; and
resilient means for entirely movably supporting the cylindrical
conductor and having orthogonally directed, helical and spiral
components with respect to the stationary conductor for minimizing
contact bounce and maintaining the cylindrical conductor in
prolonged contact with the stationary conductor when the switch is
disturbed,
the helical component extending coaxially with the stationary
conductor and the spiral component comprising continuous
filamentary turns of progressively varying radius extending
radially from the helical component toward the stationary
conductor.
5. A disturbance sensitive switch as set forth in claim 4 wherein
the supporting resilient means is a volute spring.
6. A disturbance sensitive switch as set forth in claim 4 wherein
the supporting resilient means is a stepped cylindrical spring.
7. A disturbance sensitive switch as set forth in claim 4 wherein
said cylindrical conductor includes radially protruding yieldable
means for reducing the normal space between the cylindrical
conductor and the stationary conductor.
8. A disturbance sensitive switch as set forth in claim 7 wherein
the yieldable means comprises a flat spiral spring carried on the
cylindrical conductor.
9. A disturbance sensitive switch comprising:
a support;
two electrical terminals affixed to the support and electrically
insulated from one another;
an elongated conductor having one end affixed to the support and
electrically connected to one of said terminals;
a hollow conductor disposed in encircling relationship with a
portion of the elongated conductor and electrically connected to
the other of said terminals; and
resilient means for entirely movably supporting the hollow
conductor and having a helical component directed longitudinally
and a spiral component directed transversely with respect to the
elongated conductor for maintaining the hollow conductor in
normally spaced balanced relationship with the elongated conductor
independently of the orientation of the switch in the static
state.
10. A disturbance sensitive switch as set forth in claim 9 wherein
the resilient means comprises a spring having a helical component
disposed in normally spaced coaxial relationship with the elongated
conductor and a spiral component comprising continuous filamentary
turns of progressively decreasing radius extending radially inward
from the helical component toward the elongated conductor.
11. A disturbance sensitive switch as set forth in claim 10 wherein
the spring is a volute spring disposed in surrounding relationship
with the elongated conductor and electrically insulated therefrom,
said spring having a larger diameter end affixed to the support and
an opposing smaller diameter end secured to the hollow
conductor.
12. A disturbance sensitive switch as set forth in claim 10 wherein
the hollow conductor comprises a conductive ring carried on the
smaller diameter end of the volute spring.
13. A disturbance sensitive switch as set forth in claim 12 wherein
the hollow conductor further comprises a flat spiral spring carried
on the ring and having an inner diameter less than the inner
diameter of the ring but sufficiently large to be spaced from the
elongated conductor when the switch is undisturbed.
14. A disturbance sensitive switch as set forth in claim 10 wherein
the spring is a stepped cylindrical spring disposed in spaced
surrounding relationship with the elongated conductor, the spring
having a larger diameter end affixed to the support and an opposing
smaller diameter end secured to the hollow conductor.
15. A disturbance sensitive switch as set forth in claim 14 wherein
the hollow conductor is a conductive cup disposed in enveloping
relationship with the distal end of the elongated conductor and
secured to the smaller diameter end of the spring.
16. A disturbance sensitive switch comprising:
a cup-shaped conductor defining a cavity;
a conductive support disposed adjacent the opening of the
cup-shaped conductor and insulatingly attached to the wall
thereof;
a conductive mass disposed within the cavity in the conductor;
and
resilient means for entirely supporting the conductive mass and
having orthogonally directed helical and spiral components with
respect to the wall of the conductor for maintaining the conductive
mass in normally spaced balanced relationship with the surrounding
wall of the cavity independently of the orientation of the switch
in the static state and for maintaining the conductive mass in
prolonged contact with said wall when the switch is disturbed,
the helical component of the resilient means being disposed
coaxially within the cup-shaped conductor and the spiral component
comprising continuous filamentary turns of progressively increasing
radius extending radially outward from the helical component toward
the wall of the conductor.
17. A disturbance sensitive switch as set forth in claim 16 wherein
the resilient means comprises an inverted volute spring axially
disposed within and normally spaced from the surrounding wall of
the cavity, the spring having a smaller diameter end affixed to the
conductive support and an opposing larger diameter end secured to
the conductive mass.
18. A disturbance sensitive switch as set forth in claim 17 wherein
the conductive mass is a disc transversely disposed in the cavity
and carried on the larger diameter end of the volute spring.
Description
BACKGROUND OF THE INVENTION
This invention is related, generally, to control devices and is
concerned, more particularly, with a sensitive spring-type
electrical switch having a prolonged closure time when mechanically
disturbed.
One type of disturbance responsive device comprises a motion
sensitive, electrical switch which is generally maintained in the
"open" position and, when disturbed, closes to complete an
associated electrical circuit. Usually, the circuit includes a
source of electrical energy, such as a battery, for example; and
the resulting flow of electrical current through the switch is an
indication that the switch has been disturbed by motion, physical
shock, vibration or the like. This flow of current may energize a
simple-indicating device, such as an alarm, for example, in the
circuit associated with the switch; or it may actuate more
sophisticated telemetry equipment, such as recording devices, for
example, in a connecting auxiliary circuit. Typically, disturbance
sensitive switches may be attached to parts of machinery to
indicate the presence of vibration when a malfunction occurs or a
change in position of the switch support when movement thereof
occurs. However, these sensitive electrical devices also are used
in burglar alarm systems or other protective apparatus of that
nature to sound an alarm.
A disturbance switch basically comprises a housing having therein a
movable conductive member which is adapted to engage a stationary
conductive member affixed to the housing. Numerous prior art
switches of this type utilize a pivotally supported pendulum as the
movable conductive member. In some instances, the pendulum is
caused to oscillate and thereby engage the stationary conductive
member. In other instances, the switch housing rotates around the
free-hanging pendulum thereby bringing the affixed conductive
member into contact with the pendulum. In each instance, however,
this type of disturbance switch is dependent upon the force of
gravity for its proper operation. Thus, if a disturbance switch of
the described type is inverted, it will not function as a switch at
all. This limitation on the use of disturbance switches of the
pendulum type is a serious disadvantage when a plurality of
disturbance switches are placed at random over a wide area.
Situations of this nature require disturbance sensitive switches
which are not dependent on orientation in order to operate
properly.
Some types of disturbance switches shown in the prior art have
movable conductive members which strike stationary conductive
members and rebound, thereby closing associated electrical circuits
only momentarily. The resulting low value of current flow through a
switch of this type may be adequate for activating a simple
indicating device, such as a flashing light, for example. However,
more complex telemetry devices require a stronger flow of current
through the switch and, therefore, a longer closure time interval.
Consequently, some disturbance switches of the prior art are
provided with mechanical latching means for locking a movable
conductive member into steady-state engagement with a stationary
conductive member after contact is made. However, switches of the
mechanical latching type, generally, require manual resetting in
order to return the movable member to its initial operating
condition. Consequently, there is a definite need for a disturbance
switch having a prolonged closure time interval and which returns,
automatically, to its initial operation condition when the closure
interval is completed.
SUMMARY OF THE INVENTION
Accordingly, this invention provides a disturbance sensitive switch
comprising an elongated stationary conductor disposed in spaced
coaxial relationship with a conductive mass which is movably
supported by resilient means. The resilient supporting means
includes axial and transverse resilient components, relative to the
stationary conductor, which components counteract the force of
gravity acting on the conductive mass, regardless of the
orientation of the switch. Thus, in the static state, the axial and
transverse components of the resilient supporting means hold the
conductive mass in balanced spaced relationship with the stationary
conductor, thereby maintaining the switch in a normally "open"
position.
In operation, the slightest disturbance will jar the conductive
mass out of its balanced equilibrium condition and cause it to move
transversely with respect to the stationary conductor. As a result,
the resilient supporting means will be distorted out of its natural
state, and a portion of the conductive mass will come into contact
with the stationary conductor. The contacting portion of the
conductive mass will be pressed resiliently against the interfacing
portion of the stationary conductor by the transverse component of
the resilient supporting means, thereby minimizing the possibility
of contact bounce. The axial component of the supporting means will
yield resiliently to allow the conductive mass to pivot and thereby
bring a larger area of the mass into contact with the stationary
conductor. Thus, the closure time of this inventive disturbance
switch will be prolonged until the elastic recovery action of the
resilient supporting means draws the conductive mass away from the
stationary conductor. In the absence of continued disturbance, the
resilient supporting means will return to its static rest position,
and the conductive mass will again be supported in spaced, coaxial
relationship with the stationary conductor. Thus, the disturbance
switch of this invention is restored automatically to its normally
"open" position, after the prolonged closure time interval is
completed.
One exemplary embodiment of this inventive switch comprises a
frustoconical spring having a fixed, large diameter end and a free,
smaller diameter end which supports a conductive ring in normally
spaced, encircling relationship with a conductive center post. The
ring and supporting spring constitute the movable member of the
switch and the center post constitutes the stationary member. The
frustoconical spring, commonly called a "volute spring," is
essentially a cylindrical helical spring in the axial direction and
a flat spiral spring in the transverse direction. The resiliency of
the volute spring is predetermined to counteract the force of
gravity acting on the ring, regardless of the orientation of the
switch.
An alternative embodiment of this novel disturbance switch
comprises an inverted volute spring having a fixed, small diameter
end and a free, larger diameter end which supports a conductive
disc in normally spaced, coaxial relationship with a surrounding,
conductive wall of the switch enclosure.
Another alternative embodiment of this inventive switch comprises a
stepped, cylindrical spring supporting a conductive cup in normally
spaced, enveloping relationship with the distal end of a conductive
center post. The stepped, cylindrical spring is, essentially, a
helical spring having one end connected to an axially aligned,
helical spring of larger diameter by a transversely disposed,
spiral spring.
A third alternative embodiment, which constitutes an improvement on
the first-mentioned exemplary embodiment, comprises a volute spring
supporting a conductive ring in normally spaced, encircling
relationship with a conductive center post, the ring carrying a
parallel disposed, spiral spring of smaller inner diameter than the
ring. Thus, the spiral spring reduces the annular gap between the
inner diameter of the ring and the periphery of the center post,
thereby rendering the switch more sensitive to slight disturbances.
When the ring moves transversely with respect to the center post,
the inner diameter of the spiral spring will contact the center
post before the ring and will yield resiliently to allow a radially
aligned portion of the ring to come into contact with the center
post. When the contacting portion of the ring is drawn away from
the center post, as previously described, the spiral spring will
retain contact with center post for a short time thereafter.
Consequently, the spiral spring carried on the ring will increase
the closure time of the switch.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention,
reference is made to the accompanying drawings wherein:
FIG. 1 is an axial sectional view of a disturbance switch embodying
this invention disposed in an upright position and including a
schematic diagram of a typical connecting circuit;
FIG. 2 is an axial sectional view of a disturbance switch of the
prior art with a schematic diagram of a typical connecting
circuit;
FIG. 3 is an axial sectional view of the disturbance switch in FIG.
1 disposed in a prone position;
FIG. 4 is a cross-sectional view of the switch shown in FIG. 3,
taken along the line 4--4, looking in the direction of the
arrows;
FIG. 5 is an axial sectional view of the disturbance switch shown
in FIG. 1 at the instant of closing;
FIG. 6 is an axial sectional view of the disturbance switch shown
in FIG. 5 just after the instant of closing;
FIG. 7 is an axial sectional view of an alternative embodiment of
this invention;
FIG. 8 is an axial sectional view of another alternative embodiment
of this invention;
FIG. 9 is an axial sectional view of a third alternative embodiment
of this invention; and
FIG. 10 is a cross-sectional view of the switch shown in FIG. 9
taken along the line 10--10 looking in the direction of the
arrows.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring more particularly to the drawings wherein like characters
of reference designate like parts throughout the several views,
there is shown in FIG. 2 a disturbance switch 11 of the prior art.
The switch 11 comprises a generally cylindrical housing 12 having
an enclosing cap portion 14 which is peripherally sealed, as by
welding, for example, to a circular base portion 16. The cap and
base portion 14 and 16 are made of conductive material, such as
kovar, for example, and the base 16 is provided with a centrally
disposed aperture 18 having a predetermined diameter. An axial
center post 20 of conductive material extends insulatingly through
the aperture 18 and is circumferentially sealed to the periphery
thereof. A rod 24 of conductive material is fixedly attached at one
end to the exterior surface of the base 16 and extends outwardly
therefrom in spaced relationship with the exterior portion 26 of
center post 20. The rod 24 and the exterior portion 26 of center
post 20 serve as respective terminals of the switch 11.
Disposed on the interior surface of the base 16 is a freely
rollable ball 30 of conductive material. The ball 30 has a diameter
such that it will span the dielectric bead 22 when contacting the
center post 20. Thus, the contacting ball 30 will electrically
connect the center post 20 to the base 16, thereby closing the
switch 11. Also, the distal end of the center post 20 is disposed
at a distance from the closed end of cap 14 which is less than the
diameter of the ball. Thus, when the housing 12 is inverted the
ball 30 will contact the post and will consequently close the
switch 11 by electrically connecting the post 20 to the cap 14.
However, the switch 11 will not function properly when the housing
12 is disposed on its side.
A typical circuit 32 for use with the switch 11 comprises a
charging resistor 34 and a capacitor 36 connected in series across
a battery 38, the resistor 34 being connected to the positive side
of the battery. A resistor 40 and a silicon control rectifier 42
are connected in series across the capacitor 36, the anode terminal
of the rectifier being connected to the positively charged side of
the capacitor and the base terminal being connected to the resistor
40. The terminal rod 24 is connected to the gate of the silicon
control rectifier 42 and the terminal 26 is connected to the
positive side of the battery 38. The values of the resistor 34 and
the capacitor 36 determine the time required for the battery 38 to
store a charge on the capacitor. Since the rectifier 42 is in a
normally nonconductive state, the charge remains stored on
capacitor 36 until the switch closes.
In operation, when a force moves the housing 12, the ball 30
strikes the center post 20 and rebounds, thereby closing the switch
momentarily. A typical closure time interval for this type of
switch is about 10 microseconds. The resulting low current signal
passing through the switch 11 is sufficient to trigger the gate of
the silicon control rectifier 42, thereby rendering it conductive.
Consequently, the capacitor 36 discharges through the silicon
control rectifier 42 and the load resistor 40. Thus, the load
resistor 40 may serve as a voltage source for a connecting
auxiliary circuit having telemetry devices therein which will be
activated by the current passing through the resistor 40. When the
capacitor is discharged, the rectifier returns to its initial
nonconductive state. The purpose of the rectifier in the circuit is
to provide a conductive path for discharging the capacitor through
the resistor even after the switch has reopened. Thus, a
sufficiently strong current will flow through the resistor to
activate complex telemetry devices in a connecting auxiliary
circuit (not shown). However, if the switch remained closed for a
sufficient length of time to discharge the capacitor through the
load resistor, the rectifier would not be required.
As shown in FIG. 1, the mechanical disturbance switch 50 of this
invention comprises a generally cylindrical housing 52 having an
enclosing cap portion 54 peripherally sealed, as by welding, for
example, to a circular base portion 56. The cap and base portions
are made of conductive material, such as kovar, for example. An
axial center post 60 of conductive material, such as gold plated
steel, for example, extends insulatingly through a centrally
disposed aperture 58 in the base portion 56, and is
circumferentially sealed to the periphery of aperture 58 by means
of intervening dielectric material, such as glass bead 62, for
example. A rod 64 of conductive material, such as gold plated
steel, for example, is fixedly attached at one end, as by brazing,
for example, to the exterior surface of the base 56 and extends
outwardly therefrom in spaced relationship with the exterior
portion 66 of center post 60. The rod 64 and the exterior portion
66 of the center post 60 serve as respective terminals of the
switch 50.
Within the housing 52, a frustoconical coil spring 70, commonly
called a "volute spring," is disposed in spaced surrounding
relationship with the interior portion of the center post 60. The
large end portion of spring 70 encircles a cylindrical landing 72
on the interior surface of the base 56 and is fixedly attached
thereto, as by welding, for example. The small end of spring 70 is
free to oscillate and carries a conductive ring 74 which may be
made of gold plated steel, for example. The ring 74 is provided
with a shank portion 73 which is press-fitted into the small end of
spring 70 and may be fixedly attached thereto by conventional
means, such as metallic bonding cement, for example. The spring 70
is made of resilient material, such as stainless steel, for
example, and is provided with sufficient tensile strength to
counteract the force of gravity acting on the ring, regardless of
the orientation of the housing 52. Thus, in the undisturbed state,
the ring 74 is supported in spaced coaxial relationship with the
center post 60.
The volute spring 70 functions as a cylindrical helical spring in
the axial direction and as a flat spiral spring in the transverse
direction, with respect to center post 60. As shown in FIG. 1, when
the switch 50 is disposed in the upright position, the helical
component of spring 70 counteracts the force of gravity acting on
the ring 74 and determines the axial position of the ring relative
to the center post. The spiral component of spring 70 positions the
ring 74 transversely in relation to the center post 60 and
maintains the ring in spaced coaxial relationship with the center
post when the switch 50 is in the static state. In practice, when
the ring is mounted on the small end of spring 70, the helical
component of the spring yields resiliently, in the axial direction,
until the elastic force generated by spring 70 equals the force of
gravity acting on the ring 74. As a result, the coil turns of
spring 70 adjacent the ring 74 are slightly compressed in the axial
direction. However, the other coil turns of spring 70 remain
helically spaced apart and support the ring 74 resiliently in the
axial direction. Thus, in the undisturbed state, the ring 74 is
maintained in balanced spaced relationship with the center post
60.
It also may be seen in FIG. 1 that when the switch housing 50 is
inverted, the helical component of spring 70 will yield resiliently
in the axial direction until an opposing elastic force generated by
the spring equals the force of gravity acting on the ring. In this
instance, the coil turns of spring 70, adjacent the ring 74, will
be helically spaced apart a greater distance than the coil turns
adjacent the base 56. However, the spring 70 is provided with
sufficient tensile strength to retain the ring 74 in coaxial
relationship with the center post 60 when the switch housing 50 is
in the inverted position. On the other hand, if the tensile
strength of spring 70 is excessive, the sensitivity of switch 50
will be adversely affected.
In FIGS. 3 and 4, it may be seen that when the switch housing 52 is
in the prone position, the helical component of spring 70 positions
the ring 74 axially with respect to center post 60. However, the
spiral component of spring 70 counteracts the force of gravity
acting on the ring 74 and determines the transverse position of the
ring with respect to the center post 60 when the switch 50 is in
the static state. When the switch 50 is placed in the prone
position, the spiral component of spring 70 yields resiliently
until the elastic force generated by the spring equals the force of
gravity acting on the ring. Consequently, an arcuate portion of the
spiral component is compressed slightly and an opposing arcuate
portion is expanded correspondingly. In effect, as shown in FIG. 3,
the coil turns of spring 70 move more nearly into overlying
alignment on one side of the spring 70 and further out of overlying
alignment on the diametrically opposing side of the spring.
However, the spring 70 is provided with sufficient tensile
strength, in the transverse direction, to counteract the force of
gravity acting on the ring 74 and to maintain the ring in spaced
eccentric relationship with the center post 60, when the switch 50
is in the undisturbed state.
When the housing 52 is in an oblique position, the helical and the
spiral components of spring 70 cooperate in counteracting the force
of gravity acting on the ring 74 and in maintaining the ring in
spaced eccentric relationship with the center post 60. Thus, the
ring 74 is supported in balanced spaced relationship with the
center post 60 regardless of the orientation of the switch housing
52.
When the switch 50 is disturbed, as shown in FIG. 5, the ring 74 is
jarred out of the balanced equilibrium state and impelled in the
transverse direction relative to the center post 60. As a result,
the attached, smaller diameter end of spring 70 is drawn away from
its static rest position and an inner peripheral edge portion of
the ring 74 at the end remote from the spring comes into contact
with the center post 60. This initial contact portion or point is
indicated by numeral 75. Due to the corresponding distortion of
spring 70, the spiral component of the spring presses the
contacting portion 75 against the center post, thereby minimizing
the possibility of the ring striking the center post and rebounding
therefrom. The helical component of the spring 70 yields
resiliently in the axial direction and pivots the ring 74 about its
initial contacting area 75. Thus, the linear portion of ring 74 in
axial alignment with the contacting peripheral edge area 75 is
brought into interfacing relationship with a corresponding linear
surface area of the center post, as shown in FIG. 6. As a result,
the closure time of this novel disturbance switch is prolonged
until an elastic recovery force, developed by the correspondingly
distorted spring 70, draws the ring 74 away from the center post
60. Subsequently, the ring 74 and the free, smaller diameter end of
the spring 70 may oscillate for a short interval of time. However,
if the initiating disturbance has ceased, the spring will return to
its static rest position whereupon the ring 74 will be again
supported by the spring 70 in spaced coaxial relationship with the
center post 60, and the switch 50 will be restored to its normally
"open" position.
Referring again to FIG. 1, the disturbance switch 50 is shown
connected to a circuit 32a which is somewhat similar to the circuit
32 shown in FIG. 2. In circuit 32a, a charging resistor 34a and a
capacitor 36a are connected in series across a battery 38a, the
resistor 34a being connected to the positive side of the battery. A
load resistor 40a and switch 50 are connected in series across the
capacitor 36a, the load resistor 40a being connected to the
negative side of the capacitor 36a. For example, the terminal rod
64 of switch 50 may be connected to the resistor 40a and the center
post terminal 66 may be connected to the positive side of the
capacitor 36a. Thus, the switch 50 is connected in circuit 32a in
place of the silicon control rectifier 42 which is required for
proper operation of circuit 32 shown in FIG. 2.
In operation, when the switch 50 is in the normally "open" or
static condition, the battery 38a stores a charge on the capacitor
36a. Subsequently, a slight disturbance is sufficient to upset the
balanced equilibrium of ring 74 in switch 50 and cause it to engage
the center post 60 for a prolonged interval of time, as previously
described. The resulting current passing through load resistor 40a
is sufficient to trigger complex telemetry devices in an auxiliary
circuit (not shown) which may be connected across load resistor
40a. Thus, due to the prolonged closure time provided by the switch
50, the silicon control rectifier 42, shown in FIG. 2, is not
required in circuit 32a. To obtain the desired current flow from
capacitor 36a to load resistor 40a, the closure time interval of
switch 50 may be adjusted by varying the outer diameter of center
post 60, the inner diameter of ring 74 and the diameter of the wire
forming the volute coil spring 70.
FIG. 7 illustrates an alternative embodiment 78 of this inventive
disturbance switch comprising a generally cylindrical housing 80
having a cup-shaped cap portion 82 and a transversely disposed base
portion 84 which are made of conductive material, such as gold
plated kovar, for example. The base 84 is inserted into the open
end of cap 82 and peripherally sealed to the surrounding wall
thereof by an intervening annulus 86 of dielectric material, such
as glass, for example. Cap 82 and base 84 are provided with
exterior projecting portions 88 and 90, respectively, which serve
as respective terminal members of the switch.
Axially disposed within the housing 80 is an inverted volute spring
92 having a small diameter end encircling a cylindrical landing 85
on the interior surface of base 84 and secured thereto, as by
welding, for example. The opposing large diameter end of spring 92
is free to oscillate and carries a transversely disposed disc 94 of
conductive material, such as gold plated steel, for example. The
disc 94 is provided with a reduced diameter shank portion 95 which
is press-fitted into the open, large end of spring 92 and may be
affixed thereto by conventional means, such as metallic bonding
cement, for example.
The spring 92 functions as a cylindrical helical spring in the
axial direction and a flat spiral spring in the transverse
direction with respect to the cap 82. Thus, the helical component
of spring 92 positions the flat, exposed surface of disc 94 in
spaced parallel relationship with the closed end of cap 82, and the
spiral component of spring 92 positions the peripheral rim of disc
94 in spaced coaxial relationship with the surrounding wall of cap
82. The helical and spiral components of spring 92 cooperate to
maintain the disc 94 in balanced spaced relationship with the cap
when the switch is in the static state. Therefore, the spring 92 is
provided with sufficient tensile strength to counteract the force
of gravity acting on the disc 94, regardless of the orientation of
the switch housing 80.
In operation, the switch 78 functions in a similar manner to the
switch 50 shown in FIG. 1. A slight disturbance upsets the balanced
equilibrium state of the disc and causes it to move axially and/or
transversely with respect to the cap 82. As a result, an edge
portion of the disc 94 comes into initial contact with a portion of
the surrounding wall of cap 82 or with a portion of the closed end
of cap 82. In each instance, the helical and spiral components of
the spring 92 cooperate to press the contacting portion of the disc
94 resiliently against the interfacing portion of the cap 82
thereby minimizing the possibility of contact bounce occurring.
Also the helical and spiral components of the spring 92 cooperate
in pivoting the disc 94 about its initial contacting area, thereby
bringing a larger area of the disc into engagement with the cap 82.
Thus, the switch 78 will close for a prolonged interval of time and
will return automatically to a normally "open" position in a manner
similar to the switch 50 shown in FIG. 1.
FIG. 8 illustrates a second alternative embodiment of this
invention. The switch 96, shown in FIG. 8, is structurally similar
to the switch 50, shown in FIG. 1, with the exception of the
movable conductive members. In switch 96, the distal end of center
post 60 extends axially into the open end of a conductive cup 98
which is movably supported by a stepped, cylindrical spring 100.
The spring 100 is disposed in spaced coaxial relationship with the
center post 60 and comprises an axially disposed helical portion
102 which is integrally joined to an axially aligned helical
portion 106 of larger diameter by an intervening, transversely
disposed, spiral portion 104. The helical portion 106 encircles the
cylindrical landing 72 on the interior surface of base 56 and
resiliently supports the spiral portion 104 which, in turn,
resiliently supports the helical portion 102. The free end of
helical portion 102 supports and may be affixed to the cup 98 by
conventional means, such as metallic bonding cement, for example.
When the cup 98 is mounted on the free end of helical portion 102,
the spiral portion 104 may sag slightly in the axial direction with
respect to the center post 60. This sagging does not adversely
affect the operation of switch 96, but if it is found
objectionable, the sagging may be minimized by providing the spiral
portion 104 with a volute configuration.
The switch 96 clearly demonstrates the helical and spiral
components of the supporting spring required in practicing this
invention. The helical portions 102 and 106, respectively, position
the cup 98 in the axial direction, and the spiral portion 104
positions the cup 98 in the transverse direction with respect to
the center post 60. The spring 100 is provided with sufficient
tensile strength to counteract the force of gravity acting on the
cup 98, regardless of the orientation of the housing 52. Thus, the
cup is supported in balanced spaced relationship with the center
post 60 when the switch 96 is in the static state. When a
disturbance upsets the balanced equilibrium of the cup 98, the
switch 96 operates in similar fashion to the switch 50 shown in
FIG. 1, thereby minimizing the possibility of contact bounce and
achieving prolonged closure time.
A third alternative embodiment of this invention, shown in FIGS. 9
and 10, comprises a disturbance switch 110 which is structurally
similar to the switch shown in FIG. 1, with the exception of the
resiliently supported, movable contact member. The volute spring 70
in switch 110 resiliently supports a conductive ring 74a which has
an annular cavity 112 disposed in the planar surface of the ring
remote from the spring, adjacent the inner diameter thereof. A
flat, yieldable spiral spring 114 having an outer diameter slightly
larger than the outer diameter of cavity 112 is disposed in
parallel relationship with the ring 74a and press-fitted into
cavity 112. If necessary, an outer peripheral portion of spring 114
may be affixed to the curved wall of cavity 112 by conventional
means, such as metallic bonding cement, for example. The spring 114
is made of resilient material, such as stainless steel, for
example, and is provided with an inner diameter which is less than
the inner diameter of ring 74a but greater than the diameter of
center post 60. Thus, the spiral spring reduces the annular gap
between the ring 74a and the center post 60, thereby rendering the
switch 110 even more sensitive to slight disturbances than the
switch 50, shown in FIG. 1.
In operation, the spiral spring is supported, by the ring 74 and
volute spring 70, in spaced coaxial relationship with the center
post 60, when the switch 110 is in the static state. However, when
a slight disturbance occurs, the ring 74 is jarred out of its
balanced equilibrium state and moves transversely with respect to
the center post 60. As a result, the inner diameter of spiral
spring 114 comes into contact with the center post 60 and yields
resiliently as a radially aligned, arcuate portion of ring 74a
continues to travel toward the center post 60. Thus, the switch 110
is closed by the spiral spring 112 before the ring 74a engages and
makes prolonged contact with the center post 60, as previously
described. When the elastic recovery force, generated by the
distorted volute spring 70, draws the ring 74a away from the center
post 60, the spiral spring 114 retains contact with the center post
until it also eventually is drawn away by the supporting ring 74a.
Thus, the switch 110 remains closed for a short time after the
conductive ring 74a moves away from the center post 60. As a
result, the prolonged closure time provided by the switch 50, shown
in FIG. 1, is increased by having the spiral spring 114 mounted on
the conductive ring, as shown in FIGS. 9 and 10. Furthermore, in
addition to the previously mentioned variable parameters, the
closure time of switch 110 also may be varied by changing the inner
diameter of the spiral spring 114 or the diameter of the wire used
in forming the spiral spring 114 or both.
Thus, there has been disclosed herein a novel disturbance switch
which is not dependent on the force of gravity for its proper
operation, which provides a prolonged closure time and which
returns, automatically, to its initial state of readiness after
completion of the required closure interval. The disturbance switch
of this invention, essentially, comprises a stationary contact
member disposed in coaxial, normally, spaced, relationship with a
movable contact member which is supported by resilient means having
axially and transversely directed components with respect to the
stationary contact member. The orthogonally directed components of
the resilient means cooperate in counteracting the force of gravity
acting on the movable contact member, regardless of the switch
orientation, and in supporting the movable contact member in
balanced spaced relationship with the stationary contact when the
switch is in the static state. As a result, even the slightest
disturbances will jar the movable contact member out of the
balanced equilibrium state and cause it to contact the stationary
contact member, thereby closing the switch for a prolonged interval
of time.
Although this novel switch has been illustrated herein as a
disturbance sensitive device, it also may be applied to other
fields, such as centrifugal force indicators, for example. Thus,
the tensile strength of the resilient means may be adjusted to
allow the switch to close only when the switch is spinning at a
preselected angular velocity. For example, the diameter and
material of the wire forming the volute spring 70 may be so chosen
that the conductive ring 74 will move transversely with respect to
the center post 60 only when acted upon by a predetermined
centrifugal force. The switch then may be mounted offcenter on a
spinning object and closure of the switch will indicate when the
attached object has attained the preselected angular velocity.
From the foregoing, it will be apparent that all of the objectives
of this invention have been achieved by the structures shown and
described. It also will be apparent, however, that various changes
may be made by those skilled in the art without departing from the
spirit of the invention as expressed in the appended claims. It is
to be understood, therefore, that all matter shown and described is
to be interpreted as illustrative and not in a limiting sense.
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