U.S. patent number 3,893,055 [Application Number 05/351,683] was granted by the patent office on 1975-07-01 for high gain relays and systems.
This patent grant is currently assigned to Texas Instruments Incorporated. Invention is credited to Ernest M. Jost, Lyle E. McBride, Jr., Teuvo J. Santala.
United States Patent |
3,893,055 |
Jost , et al. |
July 1, 1975 |
High gain relays and systems
Abstract
High gain electrical relays are operable at very low power
levels and which, when arranged in a relay system with impedance
matching to an energizing power source, are operable at the low
power levels used in energizing integrated circuits. The relays
utilize nickel-titanium alloy wires which are conditioned and
arranged to display sharp, reversible changes in shape and modulus
of elasticity as the wires are heated and cooled through a
temperature transition range, the alloy wires being disposed,
preferably with impedance matching means between the wires and
energizing power sources, to be heated through the noted transition
temperature range by directing current from such low power sources
through the wires, thereby to initiate relay operation. The relay
construction provides unusually high gain so that relay operation
from such low power sources is effective for regulating operation
of various types of components used in electrical apparatus.
Inventors: |
Jost; Ernest M. (Plainville,
MA), McBride, Jr.; Lyle E. (Norton, MA), Santala; Teuvo
J. (Attleboro, MA) |
Assignee: |
Texas Instruments Incorporated
(Dallas, TX)
|
Family
ID: |
27502821 |
Appl.
No.: |
05/351,683 |
Filed: |
April 16, 1973 |
Current U.S.
Class: |
337/140 |
Current CPC
Class: |
H01R
4/01 (20130101); H01H 61/0107 (20130101) |
Current International
Class: |
H01H
61/01 (20060101); H01H 61/00 (20060101); H01R
4/01 (20060101); H01h 061/06 () |
Field of
Search: |
;337/140 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Broome; Harold
Attorney, Agent or Firm: McAndrews; James P. Haug; John A.
Baumann; Russell E.
Claims
We claim:
1. A relay comprising an electrically insulating base, stationary
contact means mounted on said base, movable contact means mounted
on said base for movement between a closed circuit position
engaging said stationary contact means and an open circuit position
spaced from said stationary contact means, spring means mounted on
said base biasing said movable contact means from one of said
positions to the other of said positions, and a metal wire secured
between said movable contact means and said base, said wire being
of a selected metal alloy to be deformed from an original length to
a second length by said spring bias as said movable contact means
is moved from said one position to said other position by said
spring bias while said alloy displays a relatively low modulus of
elasticity below a transition temperature and to abruptly return to
said original length and to display a relatively higher modulus of
elasticity to move said movable contact means back to said one
position against said spring bias with a force of at least 15 grams
when said wire is heated to said transition temperature, said wire
having a selected cross-sectional size and length to be heated from
room temperature to said transition temperature by passing
electrical current through said wire with a power input of less
than about 2 watts for permitting operation of said relay with a
gain of at least about 500 to 1 at power levels used in energizing
integrated circuits.
2. A high gain relay as set forth in claim 1 wherein said wire has
a diameter of less than about 0.004 inches.
3. A high gain relay as set forth in claim 2 wherein said wire has
a length of at least about 4 inches.
4. A high gain electrical relay operable at the low power levels
used in energizing integrated circuits comprising an insulating
base, a pair of stationary electrical contact means mounted on said
base to stand above said base in electrically insulated relation to
each other, movable electrical contact means movable between a
closed circuit position engaging and bridging said stationary
contact means and an open circuit position spaced from said
stationary contact means, spring means mounted on said base biasing
said movable contact means away from said base to said open circuit
position, electrically insulating cap means movably secured to said
base and in engagement with said movable contact means for limiting
movement of said movable contact means away from said base in
response to said spring bias, and a wire of a selected
nickel-titanium alloy secured between said cap means and base to be
deformed from an original length to a greater length by said spring
bias as said movable contact means is moved to said open circuit
position by said spring bias while said alloy displays a low
modulus of elasticity below a transition temperature and to
abruptly return to said original length and to display a relatively
higher modulus of elasticity to move said movable contact means to
said closed circuit position against said spring bias with a force
of at least about 15 grams when said wire is heated to said
transition temperature, said wire having a diameter less than about
0.004 inches to be heated from room temperature to said transition
temperature by directing electrical current through said wire with
a low power input of less than about 2 watts for permitting
operation of said relay with a gain of at least about 500 to 1.
5. A relay as set forth in claim 4 wherein said stationary contact
means have terminal portions extending from the bottom of said base
and wherein said wire has its opposite ends secured to additional
terminals mounted on said base, said additional terminals having
portions thereof extending from the bottom of said base.
6. A relay as set forth in claim 5 wherein said additional
terminals are formed of deformable, electrically conductive metal
material and are deformable for adjusting contact pressure between
said movable contact means and said stationary contact means in
said closed circuit position.
7. A relay as set forth in claim 6 wherein said cap means are
adjustably mounted on said base for adjusting spacing between said
movable contact means and said stationary contact means in said
open circuit position.
8. A relay as set forth in claim 6 wherein said movable contact
means comprises an electrically conductive bridging contact arm
having electrical contacts mounted on opposite ends of said arm and
wherein said cap means comprises a body of insulating material
having a surface engaging said movable contact arm, and a threaded
member extending through said insulating body into threaded,
adjustable engagement with said base.
9. A relay as set forth in claim 8 having multiple lengths of said
wire extending between said additional terminals and bosses on said
base and bosses on said insulating body of said cap means.
10. A high gain electrical relay operable at the low power levels
used in energizing integrated circuits comprising an insulating
header, a stationary contact member cantilever mounted on said
header to support a stationary contact at the distal end thereof, a
spring contact member cantilever mounted on said header to support
a movable contact at the distal end thereof and to bias said
movable contact to closed circuit position engaging said stationary
contact, and a wire of a selected nickel-titanium secured between
said distal end of said spring contact member and said header to be
deformed from an original length to a greater length by said spring
member bias as said spring member moves said movable contact to
said closed circuit position while said alloy displays a relatively
low modulus of elasticity below a transition temperature and to
abruptly return to said original length and to display a relatively
higher modulus of elasticity to move said movable contact out of
engagement with said stationary contact to an open circuit position
against said spring member bias with a force of at least about 15
grams when said wire is heated to said transition temperature, said
wire having a diameter less than about 0.004 inches to be heated
from room temperature to said transition temperature by directing
electrical current through said wire with a low power input of less
than about 2 watts for permitting operation of said relay with a
gain of at least about 500 to 1.
11. A relay as set forth in claim 10 wherein said spring contact
member comprises a blade spring.
12. A relay as set forth in claim 10 wherein said spring contact
member comprises a metal member having a dished portion
intermediate its ends having one end of said member fixed to said
header and having said movable contact mounted at its opposite end
so that said spring member biases said movable contact into and out
of engagement with said stationary contact with snap action.
13. A relay as set forth in claim 10 having a pair of terminals
mounted on said header, having an insulating member secured to said
distal end of said spring contact member, having said wire of said
nickel-titanium alloy with one end secured to one of said terminals
and its other end secured to said insulating member, and having a
flexible wire conductor connected at one end to said other end of
said nickel-titanium alloy wire and at its opposite end to said
other terminal.
14. A relay as set forth in claim 10 having a pair of terminals
mounted on said header, having an insulating member secured to said
distal end of said spring contact member, and having said wire of
said nickel-titanium alloy secured at its opposite ends to said
respective terminals and secured intermediate its ends to said
insulating member.
15. A relay as set forth in claim 14 having a boss secured to said
header and having multiple lengths of said wire extending between
said terminals, said boss and said insulating member.
Description
Various types of electrical apparatus could be provided with
compact and inexpensive but highly sophisticated control systems
through the use of integrated circuits which incorporate a number
of circuit elements in a single integrated circuit chip. However,
because such integrated circuits are conventionally operated at
very low power levels, integrated circuit control systems as
previously contemplated would often be effective in regulating such
apparatus only where the control systems were provided with many
additional and expensive circuit elements for amplifying control
signals and for supplying the additional power required to operate
the relatively large relays which have been conventionally used in
regulating the operation of various components in such electrical
apparatus.
It is an object of this invention to provide novel and improved
electrical relays and relay systems; to provide such relays which
are operable at very low power levels; to provide such relays
which, when impedance matched to an energizing power source, are
operable at the power levels used in energizing integrated
circuits; to provide such relays and relay systems which display
unusually high gain; to provide such relays which are operable at
such low power levels but which display sufficiently high gain for
economically regulating operation of a variety of electrical
components in conventional electrical apparatus; to provide
corresponding control devices of various types which are operable
at such low power levels; and to provide such relays and devices
which are of simple, economical and reliable construction.
Briefly described, the novel and improved relay of this invention
employs a wire of a nickel-titanium alloy which has been
conditioned and arranged so that the wire displays a sharp but
reversible change in length and a sharp or abrupt increase in
modulus of elasticity as the wire is heated to a relatively low
transition temperature. The wire is provided with significant
length and with a very fine cross-sectional size and is arranged
within the relay so that wire is adapted to be heated to its
transition temperature with a very small input of electrical energy
and so that, as the wire is heated to its transition temperature,
the wire is adapted to display its change of length and increase in
modulus of elasticity and to apply a very substantial force and
motion to a switching element, thereby to achieve unusually high
gain to effect switching of sufficient power for economically
regulating operation of various types of components in an
electrical apparatus. In preferred embodiments of the invention,
the high gain relay is combined with means matching the impedance
of the fine alloy wire to a low power source such as is used in
energizing integrated circuits.
Other objects, advantages and details of construction of the high
gain relays and systems of this invention appear in the following
detailed description of preferred embodiments of the invention, the
detailed description referring to the drawings in which:
FIG. 1 is a plan view of a preferred embodiment of the high gain
relay provided by this invention;
FIG. 2 is a side elevation view of the high gain relay shown in
FIG. 1 and including diagrammatic illustration of use of the relay
in a relay system;
FIG. 3 is a section view along ling 3--3 of FIG. 1;
FIG. 4 is a section view along the central axis of another
alternate embodiment of the relay of this invention;
FIG. 5 is a section view similar to FIG. 4 illustrating another
alternate embodiment of the relay of this invention;
FIG. 6 is a section view similar to FIG. 4 illustrating another
alternate embodiment of the relay of this invention;
FIG. 7 is a schematic diagram illustrating use of the relay of this
invention as a relay system of this invention;
FIGS. 8-16 are schematic diagrams similar to FIG. 7 illustrating
uses of relays of this invention in other alternate embodiments of
relay systems of this invention; and
FIG. 17 is a schematic diagram illustrating use of the relays of
this invention in an appliance timer relay system.
Referring to FIGS. 1-3 of the drawings, a preferred embodiment of
the high gain relay 10 of this invention is shown to include a base
member 12 which is formed of a rigid, strong, electrically
insulating material such as a molded phenolic resin and which has a
central bore 12.1 extending through the base member. The base
member is provided with four bosses 12.2 of hook-like configuration
spaced on the upper surface of the base member as shown. An
upstanding rod 14 of the same insulating material is then secured
within the base member bore 12.1 in any conventional manner along
with a pair of upstanding, L-shaped, electrically-conductive
contact arms 16, each of which has a terminal portion 16.1
extending from the bottom of the base member and each of which
extends upwardly to support a fixed contact 18 above the base
member. Preferably, as indicated at 16.2 in FIG. 2, each of the
contact arms 16 has wing portions fitted around the rod 14 for
securing the contact arms in spaced, electrically insulated
relation to each other.
With the rod 14 internally threaded as indicated at 14.1 and
provided with a counterbore 14.2, a helical coil compression spring
20 is fitted within the counterbore, and a movable, bridging
contact arm 22 formed of electrically conductive material is
disposed on top of the compression spring to support a pair of
movable contacts 24 to be engaged and disengaged with respective
fixed contacts 18. A relay cap member 26 of the previously noted
insulating material is positioned as shown in the drawings to bear
against the movable contact arm 22 and a threaded bolt 28 is fitted
through an aperture 26.1 in the relay cap member and through an
aperture 22.1 in the movable contact arm to extend through the
counterbore 14.2 into threaded engagement with the rod 14.
The relay cap member 26 is also provided with a pair of bosses 26.4
disposed on opposite sides of the cap member. A pair of input or
energizing terminals 30 are secured in any conventional manner
within respective slots 12.3 in the relay base member. Each of the
terminals 30 is formed of a stiff but deformable, electrically
conductive metal material and is provided with a terminal portion
30.1 extending from the bottom of the relay base member and with a
tang portion 30.2 extending above the base member. Both terminal
portions 30.1 of the input terminals are shown in FIG. 2 for
clarity of illustration. A thermally responsive metal actuator wire
32 is then secured at one end to a tang 30.2 of one of the input
terminals and is arranged to extend tautly over the bosses 12.2 on
the relay base member and over the bosses 26.4 on the cap member as
shown in FIG. 3 to be attached at its other end to the tang 30.2 of
the other input terminal. Preferably, a metal relay cover 33 or the
like (shown only in FIG. 2) having an adjusting aperture 33.1 is
mounted on the relay base.
In the relay of this invention, the thermally responsive wire 32 is
formed of a nickel-titanium alloy commonly called Nitinol, the
alloy preferably having a composition, by weight, of from about 54
to 56 percent nickel and the balance titanium. As is well known,
this material is characterized in that, as the material is heated
through a short transition temperature range, the material
undergoes a crystalline transformation and displays a very sharp or
abrupt change in physical properties including a very substantial
increase in modulus of elasticity, these changes being reversible
as the material is again cooled below its transition temperature
range. When properly conditioned in well known manner, the material
is also adapted to display remarkable shape memory properties as
the material is heated through its transition temperature range.
For example, when the alloy material of the wire 32 is deformed
while below its transition temperature by drawing the wire to
increase the wire length up to about 8 percent, the wire is adapted
to subsequently display remarkable shape memory and to sharply
shorten in length when the wire is thereafter heated above its
transition temperature. After subsequent cooling of the wire below
its transition temperature, the wire is again easily deformed by
drawing or stretching to again prepare the wire for displaying its
shape memory. Typically, for example, the wire 32 is formed of a
nickel-titanium alloy comprising about 55 percent nickel, by
weight, and the balance titanium, this alloy having a transition
temperature at about 60.degree.C. and having other physical
properties as follows: Ultimate tensile strength 125,000 psi
Density 6.5 g./cc. Heat capacity 0.077 cal./degree C./g.
Resistivity 80 .times. 10.sup..sup.-6 ohm-centimeters Young's
Modulus (below transition temperature) 3 .times. 10.sup..sup.-6 psi
Young's Modulus (above 12 .times. 10.sup..sup.-6 psi transition
temperature)
In this arrangement of the relay 10 of this invention, the
compression spring 20 is selected so that, with the material of the
wire 32 below its transition temperature, the compression spring
applies sufficient force to the wire to deform the wire to increase
the wire length, preferably by at least about 4 percent, and to
normally bias the movable contact arm 22 to the position shown in
FIGS. 1-3 to hold the movable contacts 24 disengaged from the fixed
contacts 18 of the relay. However, electrical current is adapted to
be directed through the wire 32 between the input terminals 30 for
electrically self-heating the material of wire 32 above its
transition temperature so that the wire is sharply shortened in
length and sharply increased in modulus of elasticity for moving
the relay cap member 26 and the bridging contact arm 22 against the
bias of the compression spring 20 to engage the movable contacts 24
with the fixed contacts 18 for closing a circuit between the fixed
contacts. As will be understood, when the material of the wire 32
is thereafter permitted to cool below its transition temperature,
whereby the modulus of elasticity of the wire material is returned
to its low initial level, the compression spring 20 again deforms
the wire 32 to increase the wire length and to return the bridging
contact arm to its open circuit position as shown in FIGS. 1-3. The
threaded bolt 28 is adjustable for varying the spacing between the
movable and fixed contacts in the relay when the contact arm 22 is
in open circuit position. The input terminals 30 are also adapted
to be deformed for adjusting tension in the wire 32 for adjusting
contact pressure between the fixed and movable contacts when the
contact arm 22 is in closed circuit position. Preferably the relay
cap member 26 has sloping surfaces 26.2 and has flange portions
26.3 extending on either side of the contact arm 22 for assuring
that the movable contact arm is maintained in proper alignment to
bridge the fixed contacts 18.
In accordance with this invention, the nickel-titanium material of
the wire 32 is adapted to display very high strength when the wire
is above its transition temperature and, accordingly, the wire used
in the relay 10 is of very small cross-sectional area on the order
of 1.5 .times. 10.sup.-.sup.5 square inches or less. On the other
hand, the wire is provided with a relatively very long length.
Typically, for example, the wire has a diameter of about 0.002
inches and a length of about 4 inches. In this arrangement, the
material of the wire is adapted to be heated to its transition
temperature with a very small input of electrical energy at low
current levels and the wire is adapted to be heated to its
transition temperature from a very low power source and, in
preferred embodiments of this invention, the wire is proportioned
as described so that the relays are operable at power levels of
about 2 watts or less or even at about 0.5 watts or less. However,
a number of lengths of the wire 32 are preferably arranged between
the base and cap members of the relay so that, when the wire is
heated to its transition temperature, substantial force is
developed in the wire in the high strength state of the wire and a
significant multiple of the force, at least about 15 grams and
preferably on the order of 160 grams, is applied to the relay cap
so that the relay contacts are held together with substantial
contact pressure and are adapted to switch very substantial
currents. In preferred embodiments of this invention, the relays of
the invention are adapted to provide a gain of at least about 500
to 1 so that, although operable at the low power levels described
above, are adapted to regulate operation of conventional components
in various types of electrical apparatus. For example, where the
alloy wire 32 has a diameter of 0.002 inches and a length of 4
inches as above described, the wire is adapted to be heated through
its transition temperature in less than a second with 100
milliamperes of current at 5 volts whereas the relay 10 is adapted
to switch 50 amperes at 120 volts between the terminals indicated
at 34 in FIG. 2. As a result, the relay is adapted to be operated
from low power sources such as are used in energizing conventional
bipolar integrated circuits and, with suitable impedance matching,
is adapted to be powered from sources used in energizing the very
low powered MOS integrated circuits. However, the gain achieved by
the relay is on the order of ten thousand-to-one and the relay is
adapted to directly regulate operation of a variety of components
used in various types of electrical apparatus.
Preferably, as is best illustrated in FIG. 2, the relay 10 of this
invention is utilized in a relay system with impedance matching
means 36 between the input terminals 30 of the relay and the relay
energizing source 38. For example, in a preferred embodiment of the
invention, the impedance matching means 36 comprises a transformer
40 arranged with its secondary winding 40.2 connected across the
relay input terminals and with its primary winding 40.1 connected
to an alternating current, relay energizing, power source
represented in FIG. 2 by the integrated circuit device 42, (or to
the power source used in energizing the integrated circuit device),
thereby to match the impedance of the integrated circuit to the
wire 32 in the relay.
Another preferred embodiment of the high gain power relay of this
invention is illustrated at 44 in FIG. 4. This relay 44 includes a
movable spring contact assembly 46 which is cantilever mounted at
one end to an electrically insulating header 48 and which carries a
movable relay contact 50 at its opposite end. The relay also
includes a similarly mounted spring contact assembly 52 supporting
a stationary contact 54 for engagement with the movable contact to
close a relay input circuit. In accordance with this invention, an
insulator 56 is also mounted at the distal end of the contact
assembly 46 and a thermally-responsive actuator wire 58 is
connected at one end to the insulator 56 and at its opposite end to
an input or energizing terminal 60 mounted on the header 48. In
addition, a flexible wire conductor 62 is connected to the actuator
wire and to a second input terminal 62 as shown. The relay is then
encased in an inert-gas-filled tube 66 hermetically sealed to the
header, the input terminals 60 and 64 as well as terminal portions
of the two spring contact assemblies also being hermetically sealed
to the header in passing to the exterior through the header. In
this arrangement, the input terminals and the wires 58 and 62 form
a relay energizing circuit for receiving power from the secondary
of an impedance matching transformer 68. The actuator wire used in
the relay 44 has been conditioned to display characteristics
similar to the wire 32 discussed with reference to FIGS. 1-3 and
the transformer 68 allows direct interface of the relay energizing
circuit with an alternating current, integrated circuit power
output or the like as previously discussed.
In operation, the contact spring assembly 46 is normally biased for
engaging the fixed and movable relay contacts while the material of
the actuator wire 58 is below its transition temperature and under
stress applied by the spring assembly. However, when sufficient
current appears at the secondary of the transformer, the wire 58 is
heated to its transition temperature so that the wire abruptly
shortens in length and pulls the contact assembly 46 upwardly to
open the relay output circuit.
Referring now to FIG. 5, another practical embodiment of the relay
of this invention is illustrated at 70. In this relay, which is
otherwise similar to the relay 44 previously described with
reference to FIG. 4, the spring contact assembly 72 is formed in a
monometallic snap-acting disc configuration so that, when the
contact 74 carried by this spring assembly is disengaged and
engaged with the stationary contact 76 carried by the other spring
assembly 78, the contact separation or engagement occurs with
improved snap-action. Further, the thermally responsive actuator
wire 80 formed of the nickel-titanium alloy previously described is
attached at one end to the input terminal 82 and at its opposite
end to the input terminal 84, the wire extending from the input
terminals through a hook-shaped insulator 86 on the spring assembly
72 and through a similar hook-shaped boss 88 mounted on the header
90. In this arrangement, the wire displays greater electrical
resistance and is adapted to apply substantially greater force in
moving the spring assembly 72 when the wire is heated to its
transition temperature.
In another embodiment of this invention illustrated at 92 in FIG.
6, a spring contact assembly 94 carrying a movable contact 96 for
engagement with a stationary contact 98 carried by a second spring
assembly 100 has its distal end secured in electrically conductive
relation to a thermally responsive actuator wire 102 of the noted
nickel-titanium alloy, the opposite end of the actuator wire being
attached to an input terminal 104. In this arrangement, current in
the relay output circuit formed by the two contacts and spring
assemblies is also directed through the actuator wire 102. As a
result, when the wire is heated to the transition temperature of
the wire material, the wire shortens in length to open the output
circuit and to also deenergize the actuator wire. Upon cooling of
the wire, the spring contact assemblies again closes both the relay
output circuit and the circuit which heats the actuator wire.
The embodiment of this invention shown in FIG. 7 comprises a
control system 106 for an electric blanket or the like utilizing a
switching device 108 having a physical structure generally
corresponding to the device 92 previously described with reference
to FIG. 6 and utilizing current-regulating temperature-sensing
elements that are particularly compatible with the switching
device. As is diagrammatically illustrated in FIG. 7, the control
106 includes a variable resistor 110 and a resistance heater 112
arranged in series across terminals 114 and 116. The terminal 114
is also connected through the normally closed relay contacts 118 of
the switching device 108 to the load 120. In addition, the
thermally-responsive actuator wire 122 in the switching device 108
is arranged in series with a resistor 124 of negative temperature
coefficient of resistivity (NTC) and with a resistor 126 of
positive temperature coefficient of resistivity (PTC) as shown in
FIG. 7, the NTC resistor being disposed in heat-transfer to the
load 120 as indicated by the broken line 128 and the PTC resistor
being in heat-transfer relation to the resistance heater 112 as
indicated by the broken line 130.
In this arrangement, application of a voltage across the terminals
114 and 116 energizes the load 120 through the normally closed
relay contacts 118 and energizes the resistance heater 112 in
accordance with the setting of the variable resistor 110, the NTC
resistor normally preventing sufficient current flow in the
actuator wire 122 of the switching device. Then, the NTC resistor
becomes heated as heat is generated by the load 120, and lowers in
resistance, whereby the actuator wire 122 is heated to its
transition temperature for opening the relay contacts to deenergize
the load 120. After a cooling period, the NTC resistor increases in
resistance to again reduce current in the actuator wire 122 until
the relay contacts again close as will be understood. As will also
be understood, adjustment of the variable resistor 110 adjusts
heating of the resistance heater 112 which through heat-transfer to
the PTC resistor 126 adjusts the cycling rate of control system
106.
Referring now to FIG. 8, there is shown a second embodiment 105 of
a control device similar to the device as set forth in FIG. 7,
corresponding elements being identified by the reference numerals
used with regard to FIG. 7. Here again the switch 108 is normally
closed and supplies current to load 120. Current also passes
through the series circuit of actuator wire 122, variable resistor
132 and NTC resistor 134. As the load 120 heats up it heats up NTC
resistor 134 as indicated by the broken lines 136, thereby
increasing the current through wire 122 until the wire lengthens
and opens switch contacts 118. Cooling of load 120 reverses the
cycle. The point at which switch 108 opens and closes is determined
by the setting of variable resistor 132. This embodiment of the
invention could be utilized, for example, as a fry pan control.
Referring now to FIG. 9, there is shown a third embodiment 107 of a
control device similar to the devices as set forth in FIGS. 7 and
8. Here again the switch 108 is normally closed. Current therefore
passes through switch 108 and load 120 and through the series
circuit of actuator wire 122, the additional series resistor 137
incorporated in the switch 108, and variable resistor 138 as well
as through PTC resistor 140 and the resistor 142. When the
temperature at the load increases, it heats resistor 140 as
indicated at 144, thereby increasing the resistance and passing
less current through the PTC resistor. This causes more current to
pass through wire 122 until the wire shortens and opens switch
contacts 118. As the load 120 cools, the resistance of PTC resistor
140 decreases and diminishes the current passing through wire 122
so that the wire cools to the temperature where it lengthens and
allows closing of the switch contacts 118. The setting of variable
resistor 138 determines the temperature of operation of the switch
108. This embodiment of this invention could be used in an oven
control.
Referring now to FIG. 10, there is shown a fourth embodiment 146 of
a control device similar to the devices as set forth in FIGS. 7 to
9. Here the switch 108 incorporating the additional resistor 137 is
normally open. In the device, as the temperature of a compartment
indicated at 148 decreases, the resistance of the PTC resistor 150
decreases while the resistance of the NTC resistor 152 increases.
This causes more current to pass through the actuator wire 122 and,
upon reaching the transition temperature, closes the switch
contacts 118 and connects power to the load 120. Increase of
temperature now causes more current to be shunted through resistor
142 and NTC resistor 152 and less current through resistor 150,
thereby causing the switch 108 to open due to lengthening of wire
122. A device of this type has application as a refrigerator
defrost control wherein buildup of ice causes the switch 108 to
close and connect power to a heater, thereby allowing the
refrigerator to defrost until sufficient frost is removed from the
refrigerator to alter the cooling rate of resistors 150 and 152 and
thus to change the cycle.
Referring now to FIG. 11, there is set forth a circuit system 154
for utilizing a low power relay such as the relay 10 previously
described with reference to FIGS. 1-3 with a high voltage-low
current source such as an MOS type of integrated circuit device 156
without requiring use of a transformer.
In accordance with this embodiment of this invention, the MOS
integrated circuit device 156, which typically has an output of
about 3 milliamps at 30 volts, is arranged to charge the capacitor
158 in about 60 milliseconds, for example, while the MOS integrated
circuit device is arranged to apply a control pulse to the
transistor 160 after the capacitor is charged for discharging the
capacitor 158 through the actuator wire 32 of the relay 10
previously described. In this arrangement, the current directed
through the wire 32 at 30 volts during capacitor discharge is
adequate to heat the wire to its transition temperature for opening
the contacts of the relay as indicated at 162. The relay may then
be latched open in any conventional manner, or, if desired, the
control pulses are applied to the transistor 160 by the integrated
circuit device at selected intervals for providing the relay with a
selected duty cycle as will be understood. In this arrangement, the
very low power MOS type of integrated circuit is arranged to
operate the low power high gain relay of this invention.
Referring now to FIG. 12, there is set forth another alternate
embodiment 164 of this invention similar to the circuit system 154
described above. In this embodiment 164 of this invention, the MOS
integrated circuit device 156 is arranged as shown in FIG. 12 to
charge capacitors 166 and 168 while also being adapted to
periodically apply control pulses to the transistor 170 and to the
transistor 172 for periodically rendering the transistors
conductive to discharge the capacitors through respective actuator
wires 174 and 176 in a relay 178. In this embodiment of this
invention, the relay 178 comprises a single-pole, double-throw
latching type of relay otherwise similar to the relays of this
invention as previously described, having any conventional means
releasably retaining the relay contacts in either of its two stable
positions. That is, the relay 178 typically has one pair of relay
contacts 180 which are normally closed and another pair of normally
open relay contacts 182. In this arrangement of system 164,
electrical energy accumulated in the capacitor 166 is periodically
applied to an actuator wire 174 in the relay 178 in response to a
control pulse from the integrated circuit device 156 for opening
the relay contacts 180 and closing the relay contacts 182 for
moving the relay from one of its stable positions to its second
stable position as will be understood. A subsequent control pulse
from the integrated circuit device is then adapted to discharge the
capacitor 168 through the other actuator wire 176 in the relay for
returning the relay to its original stable position.
In another alternate embodiment of this invention illustrated in
FIG. 13, the circuit system 184 is generally similar to the circuit
system 154 except that the capacitor 158 is charged from the power
source, indicated by terminals 186 and 188 in FIG. 13, used in
energizing the integrated circuit device 156.
In another alternate embodiment of the circuit system of this
invention, as illustrated at 190 in FIG. 14, a relay 10 such as has
been previously described with reference to FIGS. 1-3, and which is
preferably energized from a 6 volt source, is arranged to be
operated from a 30 volt power source or the like such as is used in
energizing the MOS integrated circuit device for operating the
relay without excessive power loss. In this arrangement, the
integrated circuit device 192 is adapted in any conventional manner
to provide a series of control pulses to the transistor 194 so that
current from the 30 volt power source or the like indicated by the
line terminals 196 and 198 is rapidly switched on and off to
provide an effective (rms.) voltage of about 6 volts to the wire 32
in the relay 10 for heating the wire to its transistion temperature
for opening the relay contacts. While this circuit system is
adapted for use with various line voltages, greatest economy and
efficiency is achieved where the line voltage is on the order of 24
to 30 volts.
In another alternate embodiment of this invention as indicated at
200 in FIG. 15, the circuit system is arranged to match the
impedance of a higher voltage power source such as a 110 volt a.c.
line as indicated by the terminals 202 and 203 to the relay 10 by
phase modulation. That is, the MOS integrated circuit device 204 is
arranged to be energized from a 30 volt a.c. power source indicated
by the terminals 206 and 208 which is synchronized with the 110
volt source, the integrated circuit device being adapted in any
conventional manner to apply gating pulses to the SCR 210 only as
the alternating line voltage and current approach zero, thereby to
reduce the rms voltage applied to the actuator wire 32 in the relay
10 to about one-fifth of line voltage as required for heating the
wire 32 to its transition temperature for opening the contacts of
the relay 10. In this arrangement, a relatively inexpensive circuit
component 210 is adapted to be used even though the relay is being
impedance matched to a 110 volt line. As will be understood, a
triac can be substituted for the SCR 210 for providing operation
during both halves of the circuit cycle.
In another alternate embodiment of this invention as illustrated at
212 in FIG. 16, the relay 10 of this invention is impedance matched
to a d.c. power source by use of an inductance coil 214. That is,
as is shown in FIG. 16, an inductance coil 214 is arranged in
series with the actuator wire 32 of the relay 10 and with a 30 volt
d.c. power source or the like indicated by the terminals 216 and
218 whereas an MOS integrated circuit device 220 is adapted in any
conventional manner to apply brief control pulses to the transistor
222 for periodically rendering the transistor conductive. In this
arrangement, the inductive coil is selected to provide a selected
phase relationship as the transistor is being briefly rendered
conductive, thereby to apply significantly less than peak line
current and voltage to the actuator wire 32 as required for heating
the wire to its transition temperature for opening the contacts of
the relay 10.
In another embodiment of this invention indicated at 224 in FIG.
17, the high gain relays 10 of this invention as previously
described are arranged for use with a low voltage, low power
appliance timer 226 of otherwise conventional design, whereby the
timer contacts are adapted to be of very light construction while
displaying a long service life. That is, as is shown in FIG. 17, a
low voltage low power appliance timer of conventional design is
shown to include a synchronous motor 228 which rotates a drum 232
on a shaft 230 so that timer contacts 234 disposed at different
locations on the surface of the drum 232 are sequentially engaged
with respective wiping contacts 236. As will be understood, a slide
238 is typically arranged for moving the wiping contacts 236 to
engage other sets of timer contacts 240 or 242 for changing the
program provided by the drum. As will be understood, a 110 volt
a.c. power supply indicated by the terminals 244 and 246 is
arranged to energize various electrical components such as the
solenoids 248, 250 and the motor 252 through contacts of the
respective relays 10.
In accordance with this invention, a transformer 254 is connected
across the line terminals and the transformer secondary 254.1 is
arranged to energize a timer motor 228 at 12 volts for example. The
actuator wires 32 of the relays 10 are then arranged to be
sequentially connected to the transformer secondary through the
timer drum contacts 234 and the wiping contacts 236 as the timer
drum is rotated as will be understood. In this way, using the high
gain relays 10 of this invention, it is possible to utilize a low
voltage low power timer mechanism 226 which can be of very light
construction in sequentially operating a variety of electrical
components such as the solenoids 248, 250 and the motor 252. Where
desired, a resistor 256 of negative temperature coefficient of
resistivity is arranged in series with the wire 32 to serve as a
limit control.
It should be understood that although various embodiments of this
invention have been described above by way of illustration, this
invention includes all modifications and equivalents of the
described embodiments falling within the scope of the appended
claims.
* * * * *