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April 7, 1959 'A. C.QB`ERNSTEIN `2,881,365
NEUTRAL RELAY '
Filed Nov. 4, 1955
Zuj
INVENTOR
ALLAN C`. BERNSTE/N
I BY TM
ATTORNEY
United States Patent "a C6 2,881,365
Patented Apr. 7, 1959
1 2 .
relay of high sensitivity and magnetic e?iciency. These,
and still further objects, will become apparent from
2,881,365 the following description read in conjunction with the
drawings in which: .
NEUTRAL RELAY Figure 1 is a perspective view, partially exploded, of
Allan 'C. Bernstein, Kings Point, N.Y., assignor of one an embodiment of a relay in accordance with the inven
third to Nathaniel A. Karr, Kew Gardens, and one tion;
third to Philip H. Seaman, Bronxville, N.Y. Figure 2 is a side elevation of the relay shown in Fig
ure 1;
Application November 4, 1955, Serial No. 545,012 10 Figure 3 is a diagrammatic representation showing the
20 Claims. (Cl. 317-171) magnetic circuits of the relay shown in Figures 1 and 2,
and
Figure 4 is a diagrammatic representation showing the
magnetic circuits of a further embodiment of a relay in
This invention relates to a magnetically biased electro 15 accordance with the invention. 7
magnetic neutral relay. The neutral relay in accordance with the invention,
Neutral relays have conventionally been constructed has a ?rst magnetic circuit and a second magnetic circuit.
with a movable armature of magnetic material which is Permanent magnet means are positioned outside these
normally spring-biased to an open position and may be magnetic circuits and form a third magnetic circuit having
magnetically attracted to a closed position against the 20 a portion thereof common with the ?rst magnetic circuit.
spring force by energizing an electro-magnet constituting The magnetic circuits include an armature normally
part of the relay. biased to a ?rst position by the magnetic ?ux produced
The flux produced by the electro-magnet must produce by the permanent magnet in the third magnetic circuit.
a suf?cient force to overcome the inertia and frictional The armature is movable to its second position by ener
resistance of the armature and the elastic force of the 25 gization of the second magnetic circuit and means are
biasing spring; provided for electro-magnetically energizing the ?rst and
The use of the biasing spring is not completely satis second magnetic circuits with a magnetic ?eld opposing
factory as the same may be subject to breakdown after the magnetic ?eld caused by the permanent magnet in
extended use. The magnetic force created by the ener the portion of the ?rst magnetic circuit common with the
gizing coil in the relay must not only perform the useful 30 third magnetic circuit, whereby the armature will be
work of moving the armature and maintaining the same moved to its second position.
closed with su?icient contact pressure, but must, addi Referring to the embodiment shown in Figures 1, 2 and
tionally overcome the force of the biasing spring, which 3 of the drawing, the relay has two U- or horse-shoe
in connection with relays in which the spring effects the shaped magnetic cores 1 and 2 of magnetic material such
contact pressure on the back contacts, is not insigni?cant. 35 as soft iron or the like. The two U-shaped cores 1 and
A neutral relay is described in my United States Patent 2 are positioned side by side to form a substantially E
2,702,841 of February 22, 1955, which overcomes the shaped unit. Shims 26 of non-magnetic material are
disadvantages of the spring biased relays. positioned on the ends of the outer legs of the unit in
` The neutral relay as described in my said United States the conventional manner.
patent is a magneticaly biased relay in which the flux 40 'An armature 3 of magnetic material such as soft iron
caused by a permanent magnet maintains the armature is pivotally mounted on the pivot joint 4 supported by
of the relay in one of its two positions, and the magnetic the pivot posts 5 above the central legs of the E-shaped
?ux of the relay coil upon energization, at least par unit. The pivot joint 4 is preferably positioned directly
tially neutralizes the biasing force of the permanent mag above the inner leg of the U-shaped core 2 which is made
net while, at the same time, magnetically urging the 45 longer than the other legs to provide a minimum air
armature to its other position. gap between this leg and the armature. The pivot joint
While the neutral relay of my said United States patent may advantageously extend through the end of this leg.
completely overcomes disadvantages of the old spring The armature is pivotally movable to a ?rst position as
biased relays, the same has been found to have certain shown in Figure 2 with one end in contact with the outer
disadvantages in use. The permanent magnet is posi 50 leg of the U-shaped magnetic core 1 and a second posi
tioned directly in the magnetic vcircuit of the electro tion in which its opposite end is pivoted in contact with
magnet so that when the electro-magnet is energized, the the outer leg of the U-shaped core 2. The second posi
same has a strong demagnetizing effect upon the per tion is shown by dotted lines diagrammatically in Fig
manent magnet which may tend to permanently demagnet ure 3.
ize the same so that after a period of use, the relay may 55 An energizable coil 6 is positioned around the central
change its operating characteristics by requiring a smaller legs of the E-shaped unit. A plate of insulating ma
operating current and also developing less contact pres terial 7 is mounted on top of the armature 3 and has
sure on the back contacts when de-energized. connected to its upper portions a further plate 8 of in
Due to this possible permanent demagnetizing effect sulating material which has the electric contact 9 at one
of the electro-magnet upon the permanent magnet, the 60 end and the electric contact 10 at the other end. The
current supply for energizing the electro-magnet, must be ends of the plate 8 which bear the contacts and extend
carefully controlled, and if much larger amounts of` past the under plate 7 are somewhat ?exible.
energizing current are used than are required to operate A cover plate 11 is secured across the top of the relay
the relay, the detrimental demagnetization of the per by means of the support plates 21 which are screwed to
manent magnet will occur, and the relay operating charac 65 the outer legs of the U-shaped cores 1 and 2 respectively,
teristics will change. by the screws 22. The support plates have tabs 16 which
' One object of this invention is an electro-magnetic extend through the corresponding holes 17 of the cover
relay, of the type described above, which has permanent plate and secure the same in place.
magnetic biasing means which are not subjected to a The cover plate 11 is of an electrically insulating
strong permanent demagnetization e?fect by action of the 70 material and has four electric contacts 12, 13, 14 and 15
electro-magnet. thereon. The contacts 12 and 15 are electrically con
A further object of this invention is an electromagnetic nected to the terminal 19 whereas the contact 13 is con
` 2,881,365
1
a
nected tov the terminal 20 and the contact 14 to the ter In the embodiment shown, the magnetic ?ux from the
minal 18. permanent magnet 23 will follow the course shown by
The contacts and their connections to the terminals the solid arrows and normally bias the armature 3 to its
may be formed on the cover plate 11 by the known printed ?rst position in contact with the outer leg of the core 1.
circuit technique allowing for economical production and, Even if the armature 3 is moved to its second position
in conjunction with the extreme efficiency of the relay as shown by the dotted lines, the major portion of the
as a whole, for a remarkably small unit. magnetic ?ux from the permanent magnet will pass
The contacts 14 and 15, i.e. the back contacts, are: through the outer leg of the core 1 to the armature 3,
so.positioned that they will be short-circuited by the magnetically attracting the armature 3 to its ?rst posi--
contact 9 when the armature is in its ?rst position and 10 tion. '
the contacts 12 and 13 are so positioned that they will `In place of providing the largest air gap between the
be short-circuited by the contact 10 when the armature armature and the inner leg of the magnetic core 1, the
is in its second position. - greater reluctance of this path ,may be established in a
Due to the resiliency of the insulating plate 8 at its diiferent manner, as, for example, by inserting a body of
end, the contacts 9 and 10 may be resiliently pressed in 15 non-magnetic material at this end of the magnetic core,
contact position, allowing for a positive contact and easing etc.
the manufacturing tolerance requirements. With the armature 3 biased to its ?rst position, the
A` ?attened permanent magnet 23 is positioned be ' contact 9 short circuits the back contacts 14 and 15 where
tween the inner legs of the U-shaped cores 1 and 2 re as the contact 10 is in spaced relation- from the contacts
spectively. This magnet has its opposed polar surfaces 20 12 and 13, leaving these contacts insulated from each
on the opposed surfaces of the largest area so that the other.
same face the inner legs of U-shaped cores 1 and 2 as When a direct current is passed through the coil 6
may best be seen in Figure 3. The lines of magnetic > the magnetic cores 1 and 2 will be electro-magnetically
?ux through the permanent magnet 23 therefore run trans activated and with a suitable selection of the direction'
verse to the direction of the legs of the U-shaped units. 25 of DC. current, the magnetic ?ux will pass through the
[It has been found preferable to use a ferromagnetic ?rst and secondmagnetic circuits in a direction of the
ferrite magnet as the permanent magnet 23 though per dotted arrows so that the magnetic ?eld in the portion of
manent magnets constructed of other conventionally the magnetic circuits cornmonvto the ?rst and third cir
known magnetic material may be used for this purpose. cuits, will oppose the ?eld produced by the permanent
The support posts 5 of the pivot joint 4 may, as men 30 magnet, at least partially neutralizing the same.
tioned, be constructed as part of the inner leg of the core Due to the activation of the second magnetic circuit,
2 or may constitute separate posts positioned on either and the at least partial neutralization'of the portion
side of this leg or the permanent magnet. 1 of the circuit common to the ?rst and third magnetic cir
As may best be seen in the diagrammatic showing of cuits, with enough current passing through the coil, the
Figure 3, the U-shaped magnetic core 1 along with the 35 armature 3 will be moved to its second position, causing
portion of the armature 3 above it, forms a ?rst magnetic the contact 10 to short-circuit the contacts 12 and 13
circuit the path of which is shown by the dotted arrows and separating the contact 9 from the contacts 14 and
in the drawing. The other U-shaped core 2 forms `a sec l 15. As long as the energizing current is applied to the
ond magnetic circuit with the portion of the armature 3 coil 6, the armature will remain in this position and as
above it, the path of which may also be seen from the` 40 soon as the current is shut on", the biasing effect of the
dotted arrows. permanent magnet, will move the armature 3 back to
A third magnetic circuit is formed from the permanent its ?rst position and maintain the same in that position
magnet 23 and a portion of the other magnetic circuits. until further current is supplied to the coil 6.
The path of this third magnetic circuit is represented by With the pivot point 4 on the inner leg of the core
the `solid arrows and extends through the permanent mag
net 23 in its polar direction through the U-shaped mag 45 2 as shown in the embodiment in Figures l-3, the arma
ture 3 will notbe pivoted about its center. In order to
netic core 1 through the armature 3 to the inner leg of assure even contact pressure between both sets of con
the U-shaped magnetic core 2 and through this inner leg tacts with this arrangement, the contacts themselves may
back to the permanent magnet. be arranged on the armature equidistant from the pivot
It'should be noted that the inner leg of the U-shaped 50 point 4; the contacts 12 and 13 may be positioned in a
core 1 is shorter than the other legs of the cores so that somewhat higher plane than the contacts 14 and 15, the
the air-gap between the end of this inner leg of the core 1 spacing between the legs of the U-shaped core 2 may
and the armature 3 is greater, in any position of opera be larger than the spacing between the legs of the U
tion of the armature, than the air-gap between the arma shaped core 1 so that the armature is pivoted at its center,
ture and the other legs of the core. As a result of this, 55 etc. Furthermore, the armature should preferably be
the reluctance of the magnetic path between the armature dynamically balanced.
and the end of the inner leg of the core 1 is greater Since the permanent magnet 23 is positioned outside
than the reluctance between the armature and the other the main magnetic circuits formed upon energization
legs of the cores 1 and 2. Due to these differences in_ of the coil 6, and since the same is centrally positioned
reluctance, the flux from the permanent magnet will flow 60 in the coil with its polar direction extending substantially
through the outer of the core 1 through a portion of the normal to the polar direction of the coil, the same is
armature to the inner `leg of the core 2 thus normally subjected to a very low demagnetization effect as com
biasing the armature to its ?rst position. pared with the strength of the ?elds effected in the ?rst
Within the broad scope of the invention, it is only and second magnetic circuits. It is therefore easy to
necessary that the reluctances of the magnetic paths be
65 design the magnet so that the energization of the coil 6
tween the ends of the legs of the cores and the armature will have no permanent demagnetization effect thereon
be so chosen that the reluctance of the magnetic path to even when the current load exceeds that normally in
the ?eld of the permanent magnet is less with the arma tended for the relay, within limits likely to be encountered
ture in its ?rst position than with the armature in its in normal practice.
second position so that the armature will, when the coil It is not necessary that the permanent magnet be posi
is de-energized, always normally assume ?rst position. 70
tioned directly between the inner legs of the E-shaped
Preferably the reluctance of the magnetic path to the unit as shown in Figures 1-3. Within the broad scope
?eld of the permanent magnet should progressively de of the invention, the permanent magnet may be posi-l
crease upon the movement of the armature from the sec tioned anywhere outside the main ?ux paths caused upon.
ond position tothe ?rst position. 75 energization of the `coil. 6, provided that the same forms
2,881,365
5 6
a third magnetic circuit having a portion common with extension of the magnet 23 and is positioned in a plati◦ Jabse Service Manual Search 2024 ◦ Jabse Pravopis ◦ onTap.bg ◦ Other service manual resources online : Fixya ◦ eServiceinfo