U.S. patent number 3,656,082 [Application Number 05/075,924] was granted by the patent office on 1972-04-11 for positioning device.
This patent grant is currently assigned to International Telephone and Telegraph Corporation. Invention is credited to Roland D. Beck.
United States Patent |
3,656,082 |
Beck |
April 11, 1972 |
POSITIONING DEVICE
Abstract
A thermostat for supplying natural gas to a gas fired furnace or
the like at two different rates, depending upon the difference
between the temperature setting of the thermostat and the ambient
temperature. The thermostatic switch has a ferromagnetic armature
which is normally attracted by a fixed magnet and is selectively
attracted by a movable magnet fixed to a bimetal. A cantilever
spring wire makes it possible for the magnet to close two pairs of
contacts in the switch at different times. Both pairs of contacts
are closed with a snap action even though only one pair of movable
ferromagnetic bodies are employed.
Inventors: |
Beck; Roland D. (La Crescenta,
CA) |
Assignee: |
International Telephone and
Telegraph Corporation (New York, NY)
|
Family
ID: |
22128790 |
Appl.
No.: |
05/075,924 |
Filed: |
September 28, 1970 |
Current U.S.
Class: |
337/366; 335/205;
335/154 |
Current CPC
Class: |
H01H
37/66 (20130101); H01H 36/00 (20130101) |
Current International
Class: |
H01H
37/00 (20060101); H01H 36/00 (20060101); H01H
37/66 (20060101); H01h 001/66 (); H01h 037/66 ();
H01h 037/68 () |
Field of
Search: |
;337/54,90,134,340,344,366 ;335/145,153,205,206,207 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
7,133 |
|
May 1927 |
|
AU |
|
987,935 |
|
Mar 1965 |
|
GB |
|
Primary Examiner: Gilheany; Bernard A.
Assistant Examiner: Morgan; Dewitt A.
Claims
What is claimed is:
1. A multiple positioning device comprising: a base, a stop fixed
relative to said base; a main member movable relative to said base
toward said stop; second means including an auxiliary member
carried by said main member, said auxiliary member projecting from
said main member in a direction toward said stop; first means to
apply a first force to said main member to move it and said
auxiliary member to a first position in which said auxiliary member
contacts said stop and said main member is spaced from said stop;
said second means applying a second force to said main member to
resist movement of said main member relative to said auxiliary
member in a direction toward said stop when said auxiliary member
first lies in contact with said stop as aforesaid; and third means
for increasing said first force to overcome said second force to
cause movement of said main member into engagement with said
stop.
2. The invention as defined in claim 1, wherein said main member
including a first movable magnetic body, a second movable magnetic
body, at least one of said first and second bodies being adapted to
produce a magnetic field, bias means to resist movement of said
second body toward said first body, said third means being adapted
to move said first body to a position such that the force of
attraction between said bodies first moves said first body toward
said stop with a snap action and holds said auxiliary member
against said stop, said snap action being created by the increasing
of the said force of attraction approximately inversely with the
distance squared between said bodies, said third means also causing
a second further movement of said first body to a position in
contact with said stop, said second movement being with a snap
action when the sum of the forces separating said bodies falls
below said force of attraction due to the same said square law.
3. The invention as defined in claim 2, wherein said second means
is a first spring.
4. The invention as defined in claim 3, wherein said auxiliary
member is an integral end portion of said first spring, said bias
means being a second spring, said first spring being prestressed so
as to take no substantial deflection when it first comes to rest on
said stop, both of said first and second springs being cantilever
springs, said second spring being a leaf spring, said first spring
being a wire, a bimetal fixed to one side of said first body
opposite the side thereof on which said stop is located, a first
hole in said bimetal, a second hole in said first body, said first
and second holes lying in registration, said wire having a portion
fixed to the back of said bimetal, said wire being generally
L-shaped having a first length tying flush to and in pressure
contact with the bimetal back and a second length perpendicular
thereto extending through said registering holes, said wire
extending closer to said stop than said first body at least when
neither wire nor first body contact said stop.
5. The invention as defined in claim 2, wherein said bias means is
a first cantilever leaf spring, second and third cantilever leaf
springs disposed successively closer to said first body from said
first leaf spring, said first movement causing said first leaf
spring to contact said second leaf spring without causing said
second leaf spring to contact said third leaf spring, said second
movement causing said first leaf spring to remain in contact with
said second leaf spring and, at the same time, causing said first
leaf spring to move said second leaf spring into contact with said
third leaf spring.
6. The invention as defined in claim 5, wherein said first body is
a first permanent magnet, and a second permanent magnet fixed
relative to said stop on the side of said second body opposite that
on which said first body is located.
7. The invention as defined in claim 6, wherein said second and
third leaf springs do not contact each other when said magnets are
removed, said first and second leaf springs being mounted to
contact each other when said magnets are removed.
8. The invention as defined in claim 3, wherein said spring is
prestressed.
9. The invention as defined in claim 8, wherein a temperature
sensitive element is provided, said first body being fixed to said
element, said spring being a cantilever leaf spring having one end
fixed to said element, the other end of said spring being adapted
to be held stationary by said stop while said element moves toward
said stop so as to deflect said spring in a predetermined
direction, limit means to limit movement of said spring in a
direction opposite said predetermined direction, said spring having
a bend therein when unstressed, said bend being located between
said one spring end and said limit means, said spring lying in
pressure contact with said limit means when said spring is spaced
from said stop.
10. The invention as defined in claim 1, wherein said device is a
thermostat, a switch, said switch including first, second and third
leaf spring conductors, an envelope surrounding said conductors,
said envelope providing dust protection for said conductors and, at
the same time, acting as said stop, means mounting one end of each
conductor in a predetermined position adjacent the others inside
said envelope, said second conductor being positioned in between
said first and third conductors, said conductors being made of thin
metal strips, said strips being approximately parallel, said second
conductor having first and second electrical contacts fixed on each
side thereof, respectively, at the same position along the length
thereof, said first conductor having a third contact fixed thereto
to engage said first contact, said third conductor having a fourth
contact to engage said second contact, said third conductor having
an extension at its free end above said fourth contact, said
extension being fixed to said third conductor, an armature fixed to
the upper end of said extension, said armature being made of a
magnetic material, said switch being made of all non-magnetic
materials except said armature, a permanent magnet fixed relative
to said envelope on one side thereof opposite the side on which
said main member is positioned, said main member including a spiral
wrapped bimetal having one straight outer extremity tangent to the
spiral, said base having a hole therethrough, a shaft rotatable in,
but axially fixed in, said base hole, the inner end of said bimetal
being fixed to said shaft, said bimetal spiralling about the axis
of said shaft, said bimetal having a uniform width along its
length, the side edges of said bimetal lying in parallel planes
perpendicular to said axis, a movable permanent magnet positioned
adjacent to said bimetal extremity between said extremity and said
envelope, first and second holes in said extremity, a hole in said
movable magnet in registration with said first bimetal hole, a
first eyelet extending through said movable magnet hole and said
first bimetal hole holding said movable magnet in a fixed position
relative to said extremity, said auxiliary member being a spring
wire having a loop in a predetermined plane at one end thereof, a
second eyelet extending through said second bimetal hole and the
hole in said loop holding said one wire end in a fixed position in
flush contact with the rear side of said extremity opposite the
side on which said movable magnet is fixed, said wire being
substantially L-shaped in a plane perpendicular to said
predetermined plane, the leg of the L being bent at its juncture
with the loop so as to be held in pressure contact with the rear
side of said extremity, the base portion of the L extending through
said first eyelet, said base portion having a length sufficiently
great that when said base portion does not touch said envelope, the
end of said base portion lies closer to said envelope than does
said movable magnet, and means to turn said shaft.
Description
BACKGROUND OF THE INVENTION
This invention relates to sequencing devices, and more
particularly, to an arrangement for dividing the movement between
two magnetic bodies into two successive, discrete movements, each
of which two movements may take place over an extremely short time
in comparison to the time interval between the movements.
Although the device of the present invention will have broad
application and should not be limited to those applications
disclosed herein, the invention has been found to have exceptional
utility in a permanent magnet operated switch for providing low
fire and high fire in a gas furnace. That is, the invention may be
employed in a thermostat.
Permanent magnet operated thermostat switches are not broadly new
in the art. For example, see my abandoned application, Ser. No.
617,191 filed Feb. 20, 1967, for Magnetically Operable Reed Switch,
and the prior art patents and other prior art made of record in
said application including, but not limited to, that made of record
by me through my attorney.
In the past, a magnetically operated switch could not provide more
than one switching function in one switching direction. This was
true because once a permanent magnet became attracted to a
ferromagnetic armature and vice versa, the magnet and the armature
would accelerate toward each other until they were as close as
possible. This motion was uninterrupted. Prior art magnetically
operated switches have thus not been employed for both low fire and
high fire control.
Notwithstanding the foregoing, a magnetically operable switch is
highly reliable and may cycle several hundred thousand times
without failure. Although to the present time there has been no low
fire/high fire type magnetically operable switch, the need,
however, does in fact exist for such a device because of its high
reliability.
SUMMARY OF THE INVENTION
In accordance with the device of the present invention, the
above-described and other disadvantages of the prior art are
overcome by providing a two position switch utilizing a biased
member, the biasing force of which can be overcome.
According to one feature of the invention, a fixed magnet is used
with a movable magnet on the thermostat bimetal, and a cantilever
wire spring prevents the movable magnet from touching the glass
member of the switch when a first pair of contacts are engaged
therein. The bimetal then either releases some of its restraining
force on the fixed magnet or, in fact, applies some thereto to move
it toward the member. Thus, when the cantilever wire spring force
is overcome, the permanent magnet, in a snap action, moves against
the glass member.
It is an outstanding feature of the invention that the permanent
magnet moves with a snap action in two stages, each stage of which
may be separated by an interval of time much greater than the time
during which the snap action takes place. Thus, the switch contacts
are made positively without bounce, and arcing and welding are
avoided.
Another feature of the invention resides in the use of three leaf
springs in the switch, one leaf spring on one side carrying a
ferromagnetic armature. Movement of the armature toward the other
two leaf springs provides successive valve actuation to admit
combustible gas first at a first rate and second at a higher
rate.
The above-described and other disadvantages of the present
invention will be better understood from the following detailed
description when considered in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings which are to be regarded as merely
illustrative:
FIG. 1 is a rear elevational view of a thermostat constructed in
accordance with the present invention;
FIG. 2 is a vertical sectional view through the thermostat switch
taken on the line 2--2 shown in FIG. 3;
FIG. 3 is a transverse sectional view of the thermostat switch
taken on the line 3--3 shown in FIG. 2;
FIG. 4 is a transverse sectional view of the thermostat switch
taken on the line 4--4 shown in FIG. 2;
FIG. 5 is an enlarged longitudinal sectional view through a portion
of a bimetal strip with several structures fixed thereto;
FIG. 6 is a side elevational view of a spring wire shown in FIG.
5;
FIG. 7 is a bottom plan view of the wire;
FIG. 8 is a sectional view through the thermostat showing an
adjustment for the bimetal position;
FIG. 9 is a diagrammatic view of a heating system in which the
thermostat of the invention may be employed; and,
FIGS. 10, 11 and 12 are side elevational views of the thermostat,
partly in section, illustrating the operation thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In FIG. 1, the thermostat of the present invention is indicated at
20 including a housing portion 21 having a bimetal strip 22 mounted
thereon. A shaft 23 is rotatable with respect to housing portion 21
but is fixed axially with respect thereto with a flange 24 integral
with shaft 23, and a sector-shaped gear 25 fixed to shaft 23, as
shown in FIG. 8. A gear 26 meshes with gear 25 and is fixed to a
shaft 27 that has an integral flange 28. Shaft 27 is thus also
rotatable with respect to housing portion 21 but is axially fixed
with respect thereto. A neural control knob 29 is fixed to shaft
27. When it is desired to adjust the temperature in a room in a
building where a conventional natural gas fired furnace is used,
the rotatable position of knob 29 is adjusted.
All of the structures shown in FIG. 8 may be entirely
conventional.
From FIG. 1, it appears from the drawing that bimetal 22 is made of
a single piece of metal. However, this view is quite small, and the
separation between the two metal pieces, to be described in FIG. 5,
is not shown in FIG. 1 for clarity.
One end 30 of bimetal 22 is fixed to shaft 23, as shown in FIG. 1.
The other end of bimetal 22 is indicated at 31, and is relatively
long, flat and straight. As is conventional, bimetal 22 may have a
uniform width throughout its length equal to that shown in FIG. 8.
The side edges of the bimetal which can be seen in FIG. 1 lie in
substantially a single plane, as do the opposite edges thereof, not
shown in FIG. 1.
As shown in FIG. 1, bimetal 22 has an L-shaped cantilever spring
wire 32 fixed thereto by an eyelet 33. A movable permanent magnet
34 is fixed to bimetal 22 by means including an eyelet 35. As will
be described, wire 32 has an end portion which projects through the
hole in eyelet 35. Although magnet 34 is fixed relative to bimetal
22, when bimetal 22 moves, magnet 34 moves with it.
Housing portion 21 has four rectangular integral projections 36,
37, 38, and 39 which help support a switch 40. Switch 40 includes
an envelope 41 which may be sealed, as desired. Although the seal
does not have to be hermetic, it may be advantageous to employ a
hermetic seal, and fill the envelope with an inert gas such as
nitrogen.
A permanent magnet 42 is held in a fixed position relative to
envelope 41 by a spring clip 43. Spring clip 43 may be U-shaped
having a back portion 44 and two identical side portions 45. The
side portions 45 may be spaced a distance slightly smaller than the
vertical dimension of envelope 41 in FIG. 3 so as to grip the
envelope 41.
In calibration, envelope 41 may be moved upwardly and/or
downwardly, as viewed in FIG. 1, between projections 36-39. At the
same time, magnet 42 may be adjusted upwardly and/or downwardly by
moving spring clip 43 along envelope 41.
Switch 40 includes a ferromagnetic armature 46, shown in FIG. 2.
After the thermostat 20 is calibrated, magnet 42 does not move. It
is, thus, necessary for magnet 34 to attract armature 46 out of the
influence of magnet 42. The influence of magnet 42 on armature 46
must, thus, be less than that of magnet 34. One way in which to
reduce the influence of magnet 42 is to move it downwardly, as
viewed in FIG. 1. This reduces the torque on a leaf spring 47 to
which armature 46 is fixed by a rivet 48, as shown in FIG. 2.
After calibration, envelope 41 may be fixed to projections 36-39 by
sealing wax or other cementing compounds indicated at 49. Magnet 42
may similarly be fixed to clip 43 at 50, and clip 43 may be fixed
to envelope 41 and 51 and 52.
In FIG. 2 the structures outside envelope 41 have been omitted for
clarity. If such structures were shown in elevation in FIG. 2, they
would be in a position identical to that shown in FIG. 1. However,
in FIG. 2, the switch 40 has been greatly enlarged and the said
structures would, of course, be larger in proportion.
In FIG. 2, leaf springs 53 and 54 are provided in addition to leaf
spring 47. Electrical leads 55, 56 and 57 are electrically
connected to leaf springs 47, 53 and 54, respectively. If desired,
envelope 41 may be made of glass and hermetically sealed to and
around all three of the leads 55, 56 and 57.
Leaf spring 54 is substantially thicker than leaf springs 47 and
53. Leaf spring 54 may take some deflection, if desired, but may
take little or no deflection in many cases.
Leaf springs 47, 53 and 54 are fixed relative to each other at
their lower ends by a metal spring clip 58 which is integral with
leaf spring 54. Insulator strips 59 keep the leaf springs insulated
from each other. Projections 60, integral with clip 58, hold all
the leaf springs and insulators in compression to firmly mount the
lower ends of the leaf springs relative to each other.
A pair of projections 60 are provided at each of the upper and
lower ends of clip 58. A center pair of projections 61 may be bent
outwardly, when unstressed, so that they hold the lower ends of the
leaf springs in a fixed vertical position, as viewed in FIG. 2, by
causing a tight fit between U-shaped channels 62 and projections 61
with envelope 41 when mounted in the envelope, as shown in FIG. 2.
That is, a projection 61 may have a position 61', shown in FIG. 4,
before insertion into envelope 41. The same is true of both
projections 61.
Envelope 41 is non-magnetic. Further, none of the structures inside
envelope 41 are magnetic except armature 46. However, rivet 48 may
or may not be made of a magnetic or ferromagnetic material, as
desired.
If desired, each of the leaf prings may have equal widths, as
shown. The relative proportions are indicated in FIGS. 2, 3 and 4.
The leaf springs may have a uniform width throughout their entire
lengths. Armature 46 may have a width equal to that of leaf spring
47. Rivet 48 may be located mid-way between the side edges of leaf
spring 47.
Leaf spring 54 has a concave portion 63 over which a layer 64 is
fixed. Layer 64 may be an entirely conventional contact
material.
Contact buttons 65 and 66 are disposed through holes in springs 47
and 53, respectively. The holes through which buttons 65 and 66 are
located may be centrally located across the widths of the
corresponding springs and be of a size relative to the widths, as
shown in FIGS. 2, 3 and 4. Buttons 65 and 66 may also be made of an
entirely conventional electrical contact material as is layer 64 on
leaf spring 54.
Note will be taken that leaf spring 47 is substantially longer than
leaf springs 53 and 54. Note that button 66 does not appear to
contact layer 64, but does appear to contact button 65. This may be
the case when both of magnets 34 and 42 are removed from a position
in proximity to envelope 41.
As shown in FIG. 5, bimetal 22 may include two strips of metal 68
and 69 bonded or fixed together in the conventional way.
As stated previously, wire 32 is L-shaped and has a portion 70
which projects through the hole in eyelet 35, as shown in FIG. 5.
Portion 70 has an outer extremity 71 which projects beyond the
right side of end of magnet 34 and eyelet 35, respectively, to keep
magnet 34 from engaging envelope 41 under conditions to be
described. Extremity 71 is also shown in FIG. 5.
In FIG. 5, the manner in which wire 32 is fixed to bimetal 22 is
shown including eyelet 33. Spring 32 has a circular portion 72
which fits contiguous around the periphery of eyelet 33 and is
clamped to bimetal 22 by an eyelet flange 73. Eyelet 33 is fixed
relative to bimetal 22 by another flange 74 at its opposite
end.
Wire 32 is shown again in FIGS. 6 and 7. The shape of the wire will
be understood from FIGS. 6 and 7. A top plan view of the wire 32
will be identical to FIG. 7; however, portion 70 thereof would then
be hidden. Although the precise construction of the wire 32 need
not be used, if desired, it may have a circular cross-section
uniform throughout its entire length including the entire length of
loop 72 and the entire length of portion 70, as well as the
straight portion connecting loop 72 and portion 70.
When unstressed, wire 32 appears as shown in FIG. 6. Note in FIG. 6
that a plane tangent to the upper surface of loop 72 in FIG. 6 and
perpendicular to the paper would pass through a line 75. Note, too,
that line 75 is disposed at an angle A relative to the lower most
surface of the portion of wire 32 connecting loop 72 and portion
70.
The bend in the wire which creates angle A puts a prestress in
wires 32 when mounted in FIG. 5. This, and other features, are
provided in accordance with the device of the present invention.
However, it is to be noted that each feature of the invention may
be employed by itself or in combination with any one or more or all
of the other features without departing from the invention.
The invention has three modes of operation. These three modes are
illustrated in FIGS. 10, 11 and 12, respectively. In FIG. 10, note
will be taken that buttons 65 and 66 are spaced from each other,
and that button 66 is spaced from layer 64. Thus, no circuit is
made. Note that even though buttons 65 and 66 are in contact in
FIG. 2 when fixed magnet 42 is appropriately positioned, the
armature 46 and leaf spring 47 is pulled over to separate button 65
from button 66. At this time, bimetal 22 has not brought magnet 34
close enough to armature 46 to pull it, by the magnetic force of
attraction therebetween, out of the influence of fixed magnet
42.
When bimetal 22 brings magnet 34 close enough to envelope 41, at a
certain position, with spring extremity 71 still out of contact
with envelope 41, the magnetic force of attraction between movable
magnet 34 and armature 46 will exceed the opposite force created on
magnet 34 by bimetal 22 combined with the additive force of leaf
spring 47, and magnet 34 will move abruptly with a snap action
toward envelope 41 and armature 46 therein. At the same time,
armature 46, and leaf spring 47, will move toward magnet 34 until
leaf spring 47 reaches a final resting position, shown in FIG. 11.
Movable magnet 34 will also move to the position shown in FIG. 11
relative to envelope 41 with the extremity 71 of wire 31 in
abutment with envelope 41. In this position, wire 32 takes no
substantial deflection because of the prestress. Note, too, that in
FIG. 11, movement of leaf spring 47 toward leaf spring 53 causes
button 65 to make electrical contact with button 66, but that the
restraining forces on leaf spring 47, due to the spring force on
leaf spring 53 and the spring force of leaf spring 47, itselves,
prevent button 66 from making electrical contact with layer 64, as
shown in FIG. 11.
The change in operation from FIG. 11 to FIG. 12 may take place a
number of ways. As the bimetal 22 cools down further, it will
unwind to lessen the restraining force on movable magnet 34.
Another way is that if the spring force constant of wire 32 is
sufficiently high, it may in fact be necessary to place the outside
layer 68 in the spiral in FIG. 1 in tension to overcome the
restraining force of wire 32. In the former case, the magnetic
force of attraction between movable magnet 34 and armature 46 may
be adequate to pull these bodies together, as shown in FIG. 12. In
the latter case, such is not necessary. In either case, when the
force on magnet 34 to the left, as viewed in FIG. 11, is less than
that to the right, magnet 34 will snap from the position shown in
FIG. 11 to that shown in FIG. 12. That is, the movement of magnet
34 will be abrupt.
The snap action in each case i.e., from FIG. 10 to FIG. 11 and from
FIG. 11 to FIG. 12, is due to the inherent unstable character of
magnetically attracted bodies which either do not move at all or
which will rapidly accelerate toward each other until they contact
each other.
Note will be taken in FIG. 12 that leaf spring 47 is moved so far
to the left that not only does button 65 lie in electrical contact
with button 66, but also that button 66 lies in electrical contact
with layer 64.
In accordance with an outstanding feature of the present invention,
the operation is, as described previously, in connection with FIGS.
10, 11 and 12. Another outstanding feature of the invention is that
the steps are reversible and, in general, identical. That is, as
the bimetal 22 winds to a first extend, it will pull movable magnet
34 away from envelope 41 from the position shown in FIG. 12 to the
position shown in FIG. 11 with a snap action.
Conversely, as before, a further winding of, i.e., heating of,
bimetal 22 will cause movement of magnet 34 abruptly from the
position shown in FIG. 11 to the position shown in FIG. 10.
The device of the present invention will have a great many
applications and should not be limited to that disclosed herein.
However, the thermostat may be used with an otherwise entirely
conventional gas furnace used in dwellings or the like. The manner
of such use is indicated in FIG. 9 wherein a main burner 76 is
supplied with natural gas from an inlet 77 through two gas valves
78 and 79. Switch 40 may thus energize valves 79 and 78 in
succession, respectively, as room temperature drops. Main burner 76
may then, when ignited, provide heat at two rates. That is, heat
may be provided by burner 76 at a lower rate when only valve 79 is
energized, and at a higher rate when both valves 79 and 78 are
energized. What is known in the art as "low fire" and "high fire"
is, thus, provided.
Note will be taken that housing portion 21 acts as a base. Envelope
41, or the left side thereof as viewed in FIGS. 10, 11 and 12,
provides a stop against which the right side of eyelet 35 may abut.
Further, the said left side of envelope 41 also can act as a stop
for magnet 34 and the right end of extremity 71, as viewed in FIG.
5.
The upper end 31 of bimetal 22, shown in FIGS. 1 and 5, may be
described as a "main member." Wire 32 may be described as an
"auxiliary member." Extremity 71 thus is a portion which projects
from the "main member" as described above, in a direction toward
the said left side of envelope 41.
The phrase "first means to apply a first force to said main member
to move it" may be employed to describe magnet 34 and armature
46.
The phrase "second means between said members to apply a second
force to said main member" may include wire 32.
The phrase "third means for increasing said first force" may be
employed to describe the entire length of bimetal 22 with the
exception of end 31.
* * * * *