U.S. patent number 3,904,999 [Application Number 05/477,430] was granted by the patent office on 1975-09-09 for switching device.
This patent grant is currently assigned to Inflo Systems, Inc.. Invention is credited to Donald S. Rich, Norman Rudnick.
United States Patent |
3,904,999 |
Rich , et al. |
September 9, 1975 |
Switching device
Abstract
Disclosed is a switch housing having a generally cylindrical
shape. Cylindrically shaped magnetically permeable and electrically
conductive end members or caps are joined to one another by a
cylindrically shaped, electrical nonconductive, magnetically
impermeable sleeve. The end members or caps and sleeve enclose a
cylindrically shaped cavity. One end member or cap, within the
cavity, has a substantially hemispheric depression. In registry
with the cap hemispheric depression and movable relative thereto is
the hemispheric depression of a magnetically responsive,
cylindrically shaped, substantially electrically non-conductive
armature. Communicating with the armature hemisphere and extending
axially therefrom and within the armature is a frusto-conically
shaped recess. A cylindrical aperture provides an opening from the
frusto end of the cone to the end of the armature opposed to the
hemispheric end. A first electrical contact is defined by the
axially aligned end cap having the hemispheric recess therein. The
recess may be selectively wetted to effect electrical contact with
mercury disposed in the sphere defined by the armature and housing
recesses. A second electrical contact is an integral part of the
second end cap and includes an axially extending portion within the
cavity which projects into the cylindrical aperture of the
armature.
Inventors: |
Rich; Donald S. (Flanders,
NJ), Rudnick; Norman (Piscataway, NJ) |
Assignee: |
Inflo Systems, Inc. (Chester,
NJ)
|
Family
ID: |
23895883 |
Appl.
No.: |
05/477,430 |
Filed: |
June 7, 1974 |
Current U.S.
Class: |
335/52; 335/56;
200/209 |
Current CPC
Class: |
H01H
50/20 (20130101); H01H 29/18 (20130101) |
Current International
Class: |
H01H
50/16 (20060101); H01H 50/20 (20060101); H01H
29/00 (20060101); H01H 29/18 (20060101); H01h
029/02 () |
Field of
Search: |
;335/49,50,51,52,53,55,56 ;200/191,195,175,209,214 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Broome; Harold
Attorney, Agent or Firm: Furgang; Philip
Claims
What is claimed is:
1. A switch comprising:
a. housing means having a cavity therein;
b. an electrically conductive liquid within said cavity;
c. an armature means within said cavity and movable relative to
said housing;
said armature means and said housing defining within said cavity a
chamber;
said chamber comprises at least a first and second part;
said first part of said chamber being joined to said second part at
a common port;
the volume of said first part of said chamber being dependent upon
said relative position of said armature means such that with said
armature means in a first position, said liquid conductor is
retained substantially within said first part of said chamber; with
said armature means being at least in a second position, said
armature means displaces at least a part of said liquid conductor
from said first part into said second part of said chamber; said
port being so dimensioned such that, with said armature means being
in said first position, said volume of said first part in
combination with the forces of surface tension upon said liquid
conductor and the volume of said liquid conductor within said first
part, thereby resulting in said liquid conductor being retained
substantially in said first part; upon said armature means moving
relative to said housing to and from said second position, said
port admitting said displaced liquid conductor between said first
and second parts of said chamber; said first part being defined by
at least walls of said housing and said armature means; said second
part comprises walls of said armature means exclusive of said
housing walls;
d. at least first and second electrical contacts communicating with
said chamber from without said housing; said armature means in at
least one of said relative positions, causing said liquid conductor
to couple said electrical contacts and, in another of said relative
positions said liquid conductor not coupling said contacts; and
e. means for moving said armature means relative to said housing
thereby coupling or uncoupling said contacts to operate said
switch.
2. A switch as recited in claim 1, wherein said first part
comprises said housing having a recess therein for receiving said
liquid conductor.
3. A switch as recited in claim 2, wherein said armature means
comprises a member having a first recess therein; said armature
recess in combination with said housing recess and said housing
walls define said first part.
4. A switch as recited in claim 3, wherein said armature means
further comprises a second recess in communication with said first
recess, said communication being defined by said port, said second
recess comprises said second part of said chamber.
5. A switch as recited in claim 4, wherein said first recess in
said armature member and said housing means recess define, with
said armature in said first position, a sphere; said armature
member first recess and said housing recess each being a segment of
a sphere less than a hemisphere.
6. A switch as recited in claim 5, wherein said armature member
second recess is defined by walls lying in at least three
intersecting planes; said port being opposed to the apex formed by
said intersecting planes.
7. A switch as recited in claim 6, wherein said second electrical
contact extending from said housing and into said second part of
said chamber and said armature member moves relative to said first
and second contacts.
8. A switch as recited in claim 7, further comprises a gas within
said cavity; said armature means having an aperture communicating
with said second recess and said cavity; said second contact
passing freely through said aperture so as to come into electrical
contact with said liquid conductor with said armature means being
in said second position; said second contact and said aperture
defining therebetween a space of sufficiently small cross-sectional
dimension as to inhibit the flow of said liquid conductor and to
pass therebetween said gas so as to vent said chamber of said gas
as said liquid conductor moves into and out of said second
part.
9. A switch as recited in claim 8, wherein said armature means in
combination with said housing defines therebetween a passageway
between said armature means aperture and said first part of said
chamber to recirculate any of said liquid conductor passing between
said second electrical contact and said aperture, out of said
chamber, and within said cavity.
10. A switch as recited in claim 9, wherein said armature means
second recess is substantially frusto-conically shaped, said
aperture being substantially cylindrically shaped and extending
from the frusto end of said cone, said second contact being
substantially cylindrically shaped.
11. A switch as recited in claim 10, wherein said housing cavity is
substantially rod-shaped and said armature means relative movement
being coaxial with the principal axis of said housing; said means
for moving said armature means relative to said housing comprises
magnetic means; said armature means comprises magnetically
responsive means.
12. A switch as recited in claim 11, wherein said housing comprises
a hollow cylindrical body, closed at opposed ends by first and
second radially extending planar walls, said cavity being
substantially cylindrically shaped, said armature means being
substantially cylindrically shaped and complementing the
cylindrical walls of said housing defining said housing cavity;
said housing hemispherical recess residing in said first planar
radially extending end of said cavity; said hemispherical recess of
said armature being within a planar and radially extending end of
said armature; said frusto-conical recess and cylindrical aperture
extending axially from said armature hemisphere.
13. A switch as recited in claim 12, wherein said armature member
comprises a magnetically responsive cylindrical sleeve enclosing an
electrically non-conductive body portion; said armature having
flattened portions along the length thereof; said flattened portion
comprises said passageway; said armature having a planar radially
extending end opposed to said end having said hemisphere therein;
said planar end of said armature abutting said second planar end
surface of said housing with said armature in said first position;
said ends of said cylindrical housing being magnetically
responsive; said one contact extending axially from said second end
surface; insulating means affixed to said second planar end surface
of said housing so as to inhibit electrical contact between said
armature and said housing end.
14. A switch as recited in claim 13, wherein said housing ends
comprise first and second end members and a cylindrical
nonmagnetic, magnetically impermeable sleeve member; said first
housing end member being electrically conductive; said first
electrical contact comprises said first end member thereby forming
an axially extending electrical contact.
15. A switch as recited in claim 14, wherein at least a portion of
said hemispheric base recess being wettable by said liquid
conductor, thereby comprising a part of said first electrical
contact, said second contact being wettable by said liquid
conductor.
16. A switch as recited in claim 15, wherein said sleeve member is
an electrically conductive material affixed to said end members and
electrically insulated from at least one of said end members.
17. A switch as recited in claim 16, wherein said sleeve member is
electrically nonconductive material and affixed to said end
members.
18. A switch as recited in claim 15, wherein said second contact
comprises an integral part of said second end member.
19. A switch as recited in claim 18, wherein said first and second
end members each comprise first exterior electrical contact
portions of electrically conductive material and having a
cylindrical shape and a second, larger diameter axially aligned
electrically conductive cylindrically shaped body portion; one of
said body portions having extending therefrom a cylindrically
shaped axial extension terminating in said hemispheric recess end;
the other of said body portions having extending therefrom a
cylindrically shaped axial extension terminating in said second
contact; said sleeve having an inner diameter sufficient to
envelope said extensions and be secured thereto to form in
combination therewith said housing; said sleeve having an outer
diameter equal to the diameter of said body part outer diameters;
said liquid conductor is mercury; said magnetic means is a
coil.
20. A switch comprising:
a. a housing having a cavity therein and defined at least by a
principal axis extending substantially the length thereof;
b. an electrical conductive liquid within said cavity;
c. armature means within said cavity and movable relative
thereto;
said armature means and said housing defining within said cavity a
chamber;
said chamber comprises a first and second part;
said first part of said chamber retaining therein said liquid
conductor;
said first and second parts being conjoined at a common port;
said port being capable of permitting said liquid conductor to pass
freely between said parts in dependence upon said relative position
of said armature means;
d. at least a first and second electrical contacts communicating
with said chamber from without said housing and disposed
substantially along an axis, said axis being substantially parallel
to said principal axis; said armature means in at least one of said
respective positions, causing said liquid conductor to couple said
contacts and in another of said relative positions of said armature
means said liquid conductor not coupling said contacts; and
e. means for moving said armature means relative to said housing
thereby coupling and uncoupling said contacts so as to operate said
switch.
21. A switch as recited in claim 20, wherein said housing cavity
having rod-like shape.
22. A switch as recited in claim 21, wherein said first contact
communicates with said first part and said second contact
communicates with said second part of said chaamber.
23. A switch as recited in claim 22, wherein said volume of said
first part of said chamber being dependent upon said relative
position of said armature means such that with said armature means
in a first position, said liquid conductor being retained
substantially within said first part of said chamber; with said
armature means being at least in a second position, said armature
means displaces at least a part of said liquid conductor from said
first part into said second part of said chamber; said port being
so dimensioned such that, with said armature means being in said
first position, said volume of said first part in combination with
the surface tension of said liquid conductor and the volume of said
liquid conductor within said first part of said chamber, thereby
resulting in said liquid conductor being retained substantially in
said first part; and with said armature means moving relative to
said housing to and from said second position, said port admitting
said liquid conductor to between said first and second parts of
said chambers said movement of said displaced liquid conductor
being substantially in a path along said parallel axis.
24. A switch as recited in claim 23, wherein said parallel axis
being coincident with said principal axis and said principal axis
defining the principal axis of said rod-like cavity.
25. A switch as recited in claim 24, wherein said first part
comprises walls of said housing and said armature means and said
second part comprises walls of said armature means exclusive of
said housing walls.
26. A switch as recited in claim 25, wherein said first part of
said chamber being defined by at least a recess within said housing
and said second part being defined by a recess within said armature
means; said second contact being in communication with said second
part such that upon said armature means displacing at least a part
of said liquid conductor into second part said contacts being
coupled.
27. A switch as recited in claim 26, wherein said first and second
contact ends are spaced axially from one another.
28. A switch as recited in claim 27, wherein said armature means
having a recess which in combination with said housing recess and
said housing walls defines said first part of said chamber.
29. A switch as recited in claim 28, wherein said housing cavity is
substantially cylindrical, said armature means comprises a
magnetically responsive member, cylindrical in shape complementing
said cylindrical cavity; said means for moving said armature means
comprises a coil about the exterior of said housing; said armature
means moving in response to magnetic flux provided by said coil;
said recess in said housing comprising a segment of a sphere
substantially approximating a hemisphere, said armature having in a
planar radially extending surface in registry with said housing
hemisphere and having a recess therein of substantially the same
dimensions as said hemisphere housing recess so that in said first
position of said armature said hemisphere recesses in combination
with a space therebetween define a sphere; said second part
comprising a frusto-conical portion with the base thereof
intersecting said armature hemisphere and a cylindrical aperture
extending axially and receiving therein said second contact; a gas
within said cavity; said second contact and said aperture defining
therebetween a space for venting said gas; said armature having in
the cylindrical surface, axially extending flattened portions to
form passageways for recirculation of liquid conductor between said
aperture and said first part of said chamber; said housing
cylindrical wall about said cavity being substantially nonmagnetic
and at the opposed ends of said cavity, said housing walls being
magnetically impermeable.
Description
BACKGROUND OF THE INVENTION
This invention relates to switches and, more particularly,
electrical switches employing a liquid conductor.
Electrical switches employing a liquid conductor as a "throw" are
well known. A discussion of prior art of liquid conduuctive
switches will be found in copending applications for United States
Letters Patent for SWITCHES, Ser. No. 345,358 by Donald S. Rich,
filed Mar. 27, 1973; and for SWITCH MECHANISMS, Ser. No. 474,038 by
Donald S. Rich and Norman Rudnick and filed May 28, 1974, both
assigned to the same assignee as herein.
It will be understood that the invention herein represents an
improvement as compared with the prior devices disclosed by Schmid
in U.S. Pat. No. 3,358,109; Lanctot in U.S. Pat. No. 3,184,693, and
Ubukata et al. in U.S. Pat. No. 3,377,445. A more complete
discussion of the devices disclosed in these U.S. patents and their
deficiencies will be found in the aforementioned applications for
United States Letters Patent and is included herein by
reference.
Thus, the prior art devices exhibit certain disadvantages. The flow
of mercury or any other liquid conductor is achieved only at the
expense of either being position-sensitive (Lanctot and Ubukata et
al.) or work against gases compressed by the flow of the liquid
conductor (Schmid and Lanctot).
Of additional interest is the device disclosed by Lowry in U.S.
Pat. No. 3,673,524. In that device, a piston is in the form of a
donut and is movable within a cavity. Mercury in the cavity is
channeled from one end of the cavity to the other through the hole
in the donut. Thus, the donut acts as a conduit for the mercury
rather than as a chamber to receive the mercury.
None of the prior art devices discloses a configuration in which
contacts may be aligned along an axis of the housing. Thus, the
prior art switch devices may not be conveniently disposed for use
as a relay or other switch in which the contacts are axially
aligned.
The spacing of contacts along an axis makes for greater distances
and thereby reduces the effect of arcing. Thus, in relays of the
reed type, the contact spacing for a given voltage and current load
is often critical and arcing serves to wear the contact point.
Thus, it becomes desirable to seek a maximum amount of spacing
between contact. In reed type relays, this is often inhibited since
the contacts are spaced radially rather than axially spaced
(although the contacts do extend axially).
SUMMARY OF THE INVENTION
An object of this invention is to provide a liquid conductive
switch which will operate and be substantially insensitive to the
forces of shock and vibration and orientation.
It is another object of this invention to provide a switch which
exhibits bounce-free characteristics.
It is another object of this invention to provide liquid conductive
switch which efficiently employs a minimum number of parts, is
economic to manufacture, and simple and efficient in use.
It is still another object of this invention to provide a liquid
conductive switch in which the conductors may be conveniently
aligned and spaced along an axis for use as in a relay.
In accordance with the teachings of this invention, there is
provided a housing having a cavity therein. An armature is within
the cavity and movable relative to the housing. The armature and
the walls of the cavity define a chamber in the cavity. The chamber
comprises a first and second part. A liquid conductor is
substantially within the first part. The first part is joined to
the second part by a common port. The volume of the first part is
dependent upon the relative position of the armature means such
that with the armature in a first position, the liquid conductor is
retained substantially within the first part of the chamber. The
armature in a second position displaces at least a part of the
liquid conductor from the first part into the second part of the
chamber. The port between the parts of the chamber is dimensioned
such that with the armature means being in the first position, the
volume of the first part and the surface tensions of the liquid
conductor result in the liquid conductor being retained in the
first part. Displaced liquid conductor passes through the port. The
first part is defined by walls including walls of the housing and
armature. The second part is defined by walls of the armature
exclusive of the housing walls. There are provided at least two
electrical contacts communicating with the chamber from without the
housing. The armature means in at least one of the respective
positions within the housing causes the liquid conductor to couple
the contacts and in another of the respective position of the
armature means, the liquid conductor does not couple the contacts.
Finally, there is provided means for moving the armature means with
respect to the housing.
In another aspect of this invention, there is provided an armature
means within the cavity of a housing. The housing has a principal
axis extending along the length thereof. The liquid conductor is
found within the chamber defined by the armature and the walls of
the housing. The chamber is in two parts joined by a common port
through which the liquid conductor may pass between the first and
second part in dependence upon the position of the armature. There
are at least two electrical contacts communicating with the chamber
from without of the housing. The electrical contacts are disposed
along an axis. This axis is at least in parallel with the principal
axis of the housing. The armature means of at least one of the
respective positions causes the liquid conductor to couple the
contacts and in another respective position of the armature, the
liquid conductor does not couple the contacts. There is also
provided means for moving the armature means with respect to the
housing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic view of a switch constructed in accordance
with the teachings of this invention and showing the armature in a
first position;
FIG. 2 is a schematic view of the switch of FIG. 1 with the
armature in a second position;
FIG. 3 is a partial sectional plan view of an end of the housing of
the switch of FIG. 1;
FIG. 4 is a partial sectional plan view of another end of the
housing of the switch of FIG. 1;
FIG. 5 is a sectional plan view of the armature of FIG. 1; and
FIG. 6 is a front plan view of the armature of FIG. 5 taken along
lines 6--6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now to the drawing, there is disclosed (FIGS. 1-6) a switch
10 and components thereof. The switch mechanism may take any
convenient shape. Thus, the housing 12 has a preferably cylindrical
shape. However, the housing 12 may take any other elongated,
rod-like shape such as that having a rectangular, elliptical, or
other cross section.
The housing 12 may comprise two opposed end members 14 and 16. Each
end member 14 and 16 define therebetween the axial length of a
cavity 18 to be further defined hereinafter. It is to be understood
that the switch mechanism 10 of this invention may have any
applicable use. As disclosed herein, one preferred use is that of a
relay mechanism which is intended to be magnetically responsive. As
is well known in relay devices, the housing ends 14 and 16 may be
made of any magnetically responsive material, such as
electro-magnetic steel or the like, to provide a low reluctance
path for the flux generated for the operation of the relay. In
addition, the housing ends 14 and 16 may also serve as electrical
contacts, as will be more fully discussed hereinafter. Thus, the
ends 14 and 16 may be electrically conductive. In the alternative,
the end members 14 and 16 may be insulated from the electrical
contacts which pass therethrough into the cavity. The end members
14 and 16 may be each defined by cylindrically shaped body portions
20 and 22, respectively. Extending from planar, radially extending
ends 15 and 17 of the body portion 20 and 22 may be smaller
diameter, cylindrically shaped electrical contact members 24 and
26, respectively. Clearly, these contact members 24 and 26 may take
any other convenient shape and may, in the alternative, be the
exposed ends of contacts insulated from the body portion 20 and 22.
These contacts 24 and 26 extend in opposite directions from one
another and are intended to be coupled to electrical circuitry (not
shown).
Extending from planar radially extending axial ends 19 and 21 of
the body portions 20 and 22, respectively, and opposed to the
electrical contacts 24 and 26, may be cavity housing portions 28
and 30, respectively. Each cavity housing portion 28 and 30, which
may preferably form an integral part of the body portions 20 and
22, respectively, may be generally cylindrical in shape, extend
coaxially therewith, and have a smaller diameter than the body
portions 20 and 22. As previously indicated, the cavity housing
portions 28 and 30 may have any convenient shape. The first of the
cavity housing portions 28 may, as indicated, be cylindrical in
shape and extend coaxially from the body portion 20 of the first
end member 14. In the exposed, planar, radially extending end 31 of
the body portion 20, may be a depression 32 (FIG. 3). The
depression 32 may be, for example, a segment of a sphere.
Preferably, this segment 32 may approach but be less than a
hemisphere (hereinafter referred to as a hemisphere). The other
cavity housing part 30 of the second end member 16 may also
comprise a substantially cylindrical member extending coaxially
from the second body portion 22 and terminate in a planar radially
extending end 34. Extending from that radial end 34 may be a
smaller, wire-like axially aligned stub 36. The wire stub 36 of the
second end member 16 is opposite the hemispheric end 32 and spaced
therefrom by a cylindrical sleeve 38. This stub 36 serves as a
second electrical contact. A cylindrical sleeve 38 may be so
dimensioned as to fit snugly about the cavity parts 28 and 30 and
space them from one another. The sleeve 38 may be so dimensioned so
that the inner diameter thereof fits snugly about and may be
secured to the housing portions 28 and 30. The sleeve 38 preferably
has a low magnetic permeability. The sleeve 38 can be electrically
nonconductive. In such an instance, it may be made of glass,
plastic, or the like and be secured to the steel body portion 28
and 30 in a manner well known in the art. If good heat dissipation
is desired, the sleeve 38 may be an electrical conductor and
insulated at least from one of the end members 12 or 14.
Within the sleeve 38 and between the hemispherical depression 32 of
the first body part 28 and the radially extending wall 34 and its
axially projecting stub 36 of the second body part 30 may be a
substantially cylindrically shaped cavity 18. Within the cavity 18
and movable with respect to the housing 12, is an armature 42
(FIGS. 1, 2, 5, and 6). The armature 42 may have a generally
cylindrical configuration (or any other shape which conforms to the
shape of the cavity 18) with the principal axis of the cylinder
thereof coaxially aligned with the axis of the body parts 20 and
22.
A radial extending end 44 of the armature 42 faces the hemispheric
end 32 of the first body part 28 and has formed therein depression
46 which may take the form of, for example, a segment of the
sphere. Preferably, this segment 46 may be approximately a
hemisphere of substantially the same configuration as the
hemisphere 32 in the cavity housing part 28. The armature
hemisphere 46 may be intersected by a frusto-conically shaped
depression 48. The base 50 of the cone 48 intersects the hemisphere
46 forming a port 50 which may be substantially perpendicular to
the axis of the housing 12. The orientation of the cone 48 and
intersection or port 50 is not considered significant. The port 50
and configuration of the cone 48 are selected, however, to receive
a liquid conductor displaced by the armature, as will be more fully
discussed hereinafter. The frusto-conical depression 48 may be
symmetrical about the axis and the frusto end 52 thereof may also
be perpendicular to the axis.
An aperture 54 which may take any convenient shape, such as
cylindrical, communicates with the frusto end 52 of the cone 48 and
the opposed radially extending end 56 of the armature 42. Thus,
there is a cylindrical armature 42 having an axially extending
opening therethrough which may be defined, proceeding axially, as a
hemisphere 46 communicating with a frusto cone 48 joined to a
cylindrical aperture 54. The end 56 of the armature 48 having the
aperture 54 therein is disposed within the cavity 40 such that the
stub 36 extends into the armature 42 by way of the cylindrical
opening 54.
The armature 42 may be made of any magnetically permeable material
so as to be capable of moving in response to an applied magnetic
field. In addition, it is important that the liquid conductor
placed within the cavity 18 not electrically short the armature 42
to the contacts 32 or 28. Thus, the body 64 of the armature 42 may
be preferably made of a plastic or other electrical insulator while
the exterior thereof may comprise a cylindrical collar 66 of a
magnetically responsive material such as steel. In this respect,
the exterior configuration of the armature 42 is similar to the
armatures of the aforementioned application by Donald S. Rich and
Norman Rudnick.
A liquid conductor 58 (FIGS. 1 and 2) is disposed within the cavity
18. More particularly, the armature 42 is withdrawn to a first
quiescent position, such that its radial end 56 abuts the radial
end 34 of the cavity housing part 30 so that the substantially
hemispheric depressions 32 and 46, together with the space
therebetween, define a sphere. The liquid conductor, which may be,
for example, mercury 58, is placed within the sphere so as to
completely or substantially fill the sphere (FIG. 1).
It will be observed that the armature 42 has in the cylindrical
side flattened portions 62 (FIG. 6). The purpose of the flats 62 in
the cylindrical side of the armature 42 will be more fully
discussed hereinafter.
The armature 42 may be made of a magnetically responsive material.
Thus, as previously indicated, the armature 42 may comprise a
plastic body portion 64 enclosed by the collar or shell of a
magnetically responsive material such as steel 66. As previously
indicated, the end body portions 20 and 22, as well as the cavity
housing parts 28 and 30, may be made of a magnetically responsive
material such as, for example, steel. An insulating film 68 may be
disposed on the radial planar end surface 34 of the housing cavity
part 30, which has the stub 36 extending therefrom. The function of
the insulating film 68 will be more fully discussed
hereinafter.
In operation, it will be observed that the armature 42 will move
toward the hemispheric depression 32, thereby decreasing the volume
of that first part of a chamber defined by the hemispheric
depressions 32 and 42 and cone 48. The mercury 58 within the sphere
is displaced into the frusto-conical portion 48. It should be
observed that the port 50 which substantially defines the
intersection between the frusto cone 48 and the hemispheric
depression 46 of the armature 42 is so dimensioned such that with
the armature 42 fully withdrawn to the first position, the surface
tension of the mercury 58 is great enough to prevent the mercury 58
from entering into the conical portion 48. With the mercury
displaced by the armature 42 into the cone 48, the walls act upon
the displaced mercury 58 so that upon moving the armature 42 from
its second quiescent position (FIG. 2) to the first position (FIG.
1), the displaced mercury 58 returns to the main pool of mercury 58
in the spherical part of the chamber. The principles involved are
those as more fully discussed in the aforementioned applications
for United States Letters Patent by Rich and Rich and Rudnick. The
substantially hemispheric portions 32 and 46 come together reducing
the overall volume, and the armature 42 overcomes the surface
tension of the mercury 58.
It is noteworthy that differing from prior art devices, the portion
of the switch 10 which receives the displaced mercury 58 is solely
within the armature 42. The displaced mercury 58 is thus not
confined either solely in a housing or between an armature and a
wall of the housing. As a result, there is derived a significant
saving of space and improved symmetry, thereby simplifying the
shape of the various components and permitting a significant
reduction in space. This is a significant difference from prior art
devices.
Still another difference is that the electrical conductors are
disposed along an axis. The stub 36 is one of the electrical
contacts; the base hemispheric depression 32 in the cavity housing
part 28 is the other contact. Thus, when the mercury 58 is
displaced by the armature 42, electrical contact is made in an
axial direction. In order to insure complete electrical contact, a
portion of the hemispheric depression 32 in the cavity housing
portion 28 and the stub 36 may be wetted.
Venting of the gases and the recirculation of any mercury droplets
within the cavity 18 may be accomplished by permitting the gas to
move freely between the stub 36 and cylindrical aperture 54.
Mercury droplets that enter between the contact 36 and the aperture
54 may be recirculated by passing between the radial ends 56 and 34
and recirculate through the flats 62 of the armature 42 to the
spherical part of the chamber, thereby forming a complete
system.
It is essential that the mercury 58 not be permitted to prematurely
short the switch 10. Thus, as previously indicated, the armature 42
should be electrically nonconductive, while being magnetically
responsive. An alternative to the preferred magnetically responsive
sleeve 64 and electrically nonconductive body 62 may be an
electrical insulated ceramic of high magnetic permeability.
The insulating of the surface 34 of the cavity housing 30 with film
68 is intended to insure against premature shorting by any mercury
lodged therein that had passed between the cylindrical portion 54
and stub 36 to between the armature 42 and the end portion 30.
The hemispherical ends 32 and 46 form a sucking effect as discussed
in the aforementioned application by Rich and Rudnick which adds to
the recirculatory effect. It should be further understood that
channels for venting gases may be disposed in the frusto-conical
portion 48.
It should be observed that the electrical contacts 32 and 36 of
this switch 10 are axially disposed making this device suitable for
use as a relay. On the other hand, the coil 60 might be replaced by
a toroidal magnet (not shown) for moving the armature 42 from one
position to another, as with a push button.
A comparison between the device disclosed herein and the well known
reed relay is instructive. Here it will be observed that the
distance from the first contact 36 to the second contact 32 (which
may also comprise the pool of mercury 58) is (in FIG. 1) a
substantially larger distance than it would be for an equivalently
dimensioned reed relay where contacts are spaced radially. Thus,
there is a longer arc distance between contacts. Reed relays very
often require an inert gas under high pressure to reduce the arcing
between such contacts. For the same configuration, voltages and
current, it is clear that a lesser gas pressure will be required
for the switch 10. Further, because of the separation of the
contacts, the deletorious effect of arcing is substantially
reduced. In addition, the narrowing passageway between the
hemisphere and into the conical section 48 of the armature 42
creates a hydraulic working advantage. Thus, for small movements of
the armature, the mercury volume is displaced a long distance,
thereby providing an operational working advantage. The principles
of operation including the displacement of the mercury into the
conical section 48 and the removal therefrom, have been more fully
discussed in connection with the aforementioned applications by
Rich and Rich and Rudnick and the applicable portions are included
herein by reference.
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