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Патент USA US3046430

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July 24, 1962
Filed Dec. 31, 1958
_ .£
Bruce A . Rifzenfhaler
United States * aten
Patented July 24, 1962
Bruce Allen Ritzenthaler, Chicago, Ill., assignor to Stand
ard Oil Company, Chicago, Ill., a corporation of
Filed Dec. 31, 1958, Ser. No. 784,311
7 Claims. ((11. 307-132)
relay coil through this resistance also increases the con
tact pressure between the armature and the normally
open contact so that arcing at the latter is similarly mini
The invention will be more fully described with refer
ence to the attached ?gure.
The relay pulsing circuit of the instant invention which
activates armature 13 may be supplied with either alter
This invention relates to relay pulsing circuits, and
nating or direct current. In the drawing as shown, the
more particularly is concerned with providing means for 10 current supply is 115 volts A0. at 60 cycles per second
generating a cyclically repetitive pulse with apparatus
supplied through connections 1 and 2. Switch S-1 turns
which is characterized in having extremely long compo~
the unit on or off.
nent life.
selenium type half wave recti?er 3 is provided, along
with a series current-limiting resistor R1 and condenser
In certain electrical testing and measuring applications
To rectify this alternating current a
it is desired to produce a pulsating on-off current with the 15 C1 in shunt across the power line at connections 4 and
pulsations occurring at a frequency in the range of about
10. Current to energize relay coil 5 ?ows through the
0.1 to about 60 cycles per second. This frequency range
circuit comprising ?xed resistor R2, variable resistor R3,
is, in general, too low to permit the use of electron tube
line 19, normally closed contact 8, spring biased arma
vibrators, and as a consequence it becomes necessary to
ture 7, connection 18, and thence through coil 5. Relay
rely on conventional electromechanical relay pulsing 20 coil 5 desirably has a centrally disposed low-hysteresis
circuits. These circuits employ an armature which func
tions as an interrupter in the power line of a relay coil.
A capacitance is in shunt around the coil to prevent high
voltage arcing at the contacts. With relay pulsing circuits
iron core 6 by means of which magnetic ?ux created by
coil 5 is concentrated and acts to drive armatures 7 and
13. Condenser C2 is in shunt around relay coil 5. Re
sistor R5 is connected from connection 10 to normally
however, the requirement that the armature have a short 25 open contact point 9, while resistor R6 is connected from
period of vibration, or in other words be small in size and
connection 18 at armature 7 to line 19. It will be ob
light in Weight, frequently mitigates against extended life
served that when armature 7 is in normally closed posi
of the armature and the contact points. Since these cir
tion, power supplied to relay coil 5 is shorted around re
cuits often must operate over many millions of cycles, it
sistance R6 and hence the full current is applied to the
is evident that suitable means must be provided for se 30 coil. When armature 7 is in normally open position,
curing adequate component life.
resistance R5 is then connected in parallel with relay coil
It is well known that a condenser in series with a resist
5 and with condenser C2 so as to cause the latter to dis
ance bridged about a contact is an effective method for
charge through R5.
eliminating or reducing high temperature arcs formed up
An external load circuit in which pulsations may also
on making or breaking an electrical contact. It has also 35 be formed is represented by terminals 16 and 17 or 17
been proposed heretofore that various other combinations
of condensers and resistances may be employed for this
service. Unfortunately, the protective networks in the
and 20. When armature 13 is in the normally-closed
position no current can ?ow through the former load cir
cuit, while when armature 13 is in the normally open
prior art are not suitable for use with relay pulsing cir
position, i.e. at contact point 15, current is permitted to
cuits in which a capacitance is in shunt with the relay 40 flow in this circuit.
coil, since the circuit is already capacitive and high volt
age arcing is therefore not a problem.
The cause of arc
ing in these circuits is low contact pressure and slow arma
ture travel.
It is therefore an object of the instant invention to pro
vide an improved relay pulsing circuit having high contact
pressures and rapid armature travel to reduce arcing and
To provide an optional but highly desirable visual sig
nal to indicate each pulsation, a neon bulb 21 is con
nected in parallel with resistor R4, both of these being
nected in parallel with resistor R7. This circuit is con
45 nected between connections 4 ‘and 18.
The operation of the present relay pulsing circuit may
be described as follows.
When switch 8-1 is closed so
furnish exceptionally long contact life. A further object
as to supply power to the relay pulsing circuit, con
is to provide a simple and rugged pulsing circuit in which
denser C1 charges through selenium recti?er 3 and through
means are provided for regulating the pulse frequency. 50 current limiting resistor R1 to about 150-160 volts DC.
An additional object is to- provide a relay pulse circuit for
This ‘direct current is ultimately applied to relay coil 5.
generating pulses in the 0.1-60 cycles per second range.
Positive current ‘at connection 4 flows through ?xed re
Yet another object is to provide a relay pulsing circuit
sistor R2 and variable resistor or potentiometer R3 and
with ?xed or variable control over the portion of time
thence through normally closed contact 8, armature 7,
during which the relay remains open or closed. Other 55 and connection 8 to shunt-connected relay coil 5 and con
and more particular objects will become evident as the
description of the invention proceeds.
In accordance with the objects above, a relay pulsing
denser C2. The rate at which current is supplied to this
latter shunt combination may be varied by appropriate
adjustment of variable resistor R3; reducing the value of
resistance across resistor R3 increases the pulse generation
circuit having a conventional capacitance shunted around
the relay coil is provided with a low-resistance discharge 60 rate. Resistor R2 is provided to insure that an exces'
' path to discharge the capacitance when the armature is in
sive pulse rate is not attained.
the normally-open position, and with a high resistance
When the voltage across condenser C2 reaches about 50
path bridged across the normally-closed contact position.
volts, the current through relay coil 5 is then sutlicient to
energize armature 7 and move it from normally closed
The low-resistance discharge path, by governing the rate
at which the capacitance discharges, controls the time 65 contact 8 to normally open contact 19‘. Immediately upon
disengagement of armature 7 from normally closed con
during each cycle when the relay is closed. The high re
tact 8, and before normally open contact 9 is contacted,
sistance path which is bridged across the normally-closed
condenser C2 commences to discharge back through relay
contact provides additional current in the relay coil to
assure that the normally-closedcontact is broken so 70 coil 5. This discharge action serves to rapidly remove the
magnetic ?eld created by coil 5 and iron core 6. When,
rapidly that the tendency of the normally-closed contact
points to are is greatly reduced. Current ?owing to the
after a period of a few milliseconds, armature 7 contacts
normally open contact 9, an additional discharge path for
condenser C2 is provided by way of resistance R5. Resist
ance R5 is connected to normally open contact 9 and
external load circuit via terminals 16 and 17 or 17 and
it so that armature 13 follows the positioning of armature
7 and thereby opens and closes the second armature 13 in
synchronization with ?rst armature 7.
The relay pulsing circuit described herein has numerous
applications either by itself or in combination with other
electrical apparatus. It may for example be employed as
a pulse generator for stepper-relay sampling systems; as a
bridged about condenser C2. It is apparent, then, that
when normally open contact 9 is engaged, condenser C2
discharges more rapidly than during the brief period when
armature 7 is being repositioned.
The fraction of time during which normally open con
tact 9 is engaged is regulated by the value of resistance
pulse generator‘for testing nuclear decade-type counters,
R5. Resistance R5 may be a ?xed resistor, in which event
the relay “closed time” is relatively constant at all pulse 10 linear ampli?ers and counting rate meters; for standard
izing timing apparatus; and for other applications in which
frequency rates. However, where it is desired to vary
an intermittent circuit (with or without variable rate)
the time during each cycle when the relay is in normally
is desired. The circuit may also be used Without making
or breaking electrical load circuits, and an illustration of
employment of resistor R5, a cyclic relay pulse rate of 15 this is an electrical metronome where the audible click of
armature 7 provides the necessary sound. It has been
only 2 to about a maximum of about 10 cycles per second
open (or normally closed) position, resistor R5 may com
prise a variable resistor or potentiometer. Without the
can be attained, while with the additional capacitance
found that the relay pulse ‘circuit has been especially effec
discharge circuit provided by resistor R5 the maximum
tive in testing “wild ping” counters. “Wild ping” is a
phenomenon which occurs in internal combustion engine
cyclic rate is increased to about 60 or more cycles per
When the voltage across condenser C2 falls to about 11
volts, a spring or (less desirably) gravity bias on armature
7 exerts a physical force which, at the low voltage, is
effective to return armature 7 from normally open contact
9 to normally closed contact 8.
The above completes one cycle of operation. Another
cylinders by combustion chamber deposits randomly ignit
ing the gas-fuel mixture before the spark plug ?res. Wild
ping counters are somewhat sensitive and must be calibrat
ed frequently; the instant relay pulsing circuit is used for
generating a standard frequency pulse which is fed to
the input of wild ping counter while a visible comparison
is made of blinking lights on the relay pulse circuit and on
cycle begins immediately since condenser C2 begins charg
the counter.
ing as soon as armature 7 returns to normally closed
contact 8.
tion, the following speci?c values of resistances and
The circuit as described above, without resistance R8,
is eifective in generating relay pulses without further
modi?cation. However, it has been found experimentally
that apparatus lacking resistance R6 will function for only
a few thousand cycles, whereupon pitting occurs where
armature 7 touches normally open contact 9 and normally 35
closed contact 8. It has been discovered in further ac
cordance with the invention that the high-resistance R6
circuit bridged around normally closed contact 8 not only
increases contact life ‘well beyond several million cycles,
but also provides additional ?ow-in current for coil 5 to
assure that normally closed contact 8 is broken swiftly. It
also reduces the “in transit” time for armature 7 to travel
between normally-closed contact 8 and normally open
contact 9. Lastly, it establishes greater contact pressure
between armature 7 and normally open contact 9 These
three conditions contrive to make and break the respective
contacts very rapidly and assure strong contact pressures,
thus providing extraordinarily long contact life.
As an example of a relay pulser according to the inven
capacitances for a suitable pulse circuit are listed below.
R1_.._- ____________________________ .._
R2 _______________________________ __
R, _______________________________ _.
R, _______________________________ _R5 _______________________________ _.
R6 _______________________________ __
22 ohms 1/2 w.
470 ohms 1 w.
20 k. 2 w.
56 k. 1 w.
200 k. 10 w.
2.7 k. 1 w.
C1 ___________________ -30 microfarad, 150 volt
C2 ___________________ _.40 microfarad, 150 volt D.C.
From the above description, it is manifest that a relay
pulsing device according to the above description fully
satis?es the objects of the invention. With this device,
Resister R6 functions in the ‘circuit when the voltage
pulse frequencies in the range of about 0.1 to 60 or more
across condenser C2 reaches about 50 volts and relay coil 50 cycles per second may be conveniently established while
5 starts to reposition armature 7 from normally closed
component life—especially contact point life—is increased
contact 8 to normally open contact 9. During the “in
from the 5000 or 6000‘ cycles heretofore obtainable to
transit” time when neither contact is engaged, in the
an inde?nite life in excess of 5 million cycles. The pro
absence of resistance R6 the only current ?owing through
vision of a low resistance discharge path connected to
relay coil 5 would be the current provided by discharging 55 normally open contact 9 permits higher pulse frequencies
condenser C2. However, with the high resistance circuit
than can be attained without this path. Moreover, the
provided by resistance R6, additional current from the
inclusion of a high resistance path bridged about normally
power source is applied to coil ‘5 so as to increase its
closed contact 8 serves to rapidly make and break electri
cal contacts between armature 7 and the respective contact
provides a clean swift break of normally closed contact 8 60 points 8 and 9.
and in addition provides greater normally-open contact
It is also apparent that many variations of the inventive
9 pressure during the initial heavy current discharge of
circuit may be made within the scope of the appended
magnetic strength. This increased power to relay coil 5
condenser C2.
As shown in the drawing, the relay pulse circuit may
claims. For example, resistance R5 may be responsive
to an independent variable, such as a thermistor respon
be operatively connected to a second armature, armature 65 sive to ambient temperature, and thereby furnish a pluse
13, which is alternately positionable between normally
closed contact 14 and normally open contact 15 in a circuit
which is preferably independent electrically but dependent
cycle having a dependently variable normally-open or
normally-closed time. Similarly, resistance R3 may be
used to regulate the pulse rate in response to, say, the
magnetically on the relay pulse circuit. Dashed line 12
wiper position of a temperature or pressure indicator.
illustrates this magnetic dependency. In the same manner 70 I claim:
dashed line 11 represents the magnetic dependency of the
1. An improved electromagnetic relay pulsing circuit
?rst armature 7 at coil 5 and core 6. Armatures 7 and
which comprises: a relay coil and means for supplying
13 may be either mechanically dependent or independent
power thereto, a ?rst armature driven by said coil and
being alternately movable between normally-open and
of each other provided they both are driven by the action
of coil 5. The second armature 13 is connected into an 75 normally-closed contacts in the power supply means, a
second armature driven by said coil and connected in a
in circuit with, and actuated by, said relay coil, said arma
,load circuit, capacitance means in shunt around said coil,
ture being alternately movable between normally-open
a ?rst discharge path including a low resistance con
and normally-closed contacts, and capacitance means in
nected to discharge said capacitance means through said
shunt relationship with said relay coil, the improvement
normally-open contact whereby the portion of time when 5 comprising a low resistance discharge path connected to
the ?rst armature is engaged with the normally-closed
discharge said capacitance means through the normally
contact is controlled, and a second discharge path includ
open contact and thereby control the portion of time when
ing a high resistance bridged across the normally-closed
said armature is in the normally-closed position.
contact to- permit the application of power to said relay
6. Circuit of claim 5 including a high resistance path
coil when said ?rst armature is in the normally-open posi 10 connected through the normally-open contact to provide
tion and thereby provide rapid opening of the normally
rapid opening of the normally-closed contact and to in
closed contact and increase the contact pressure at the
normally¢open contact.
crease contact pressure at the normally-open contact,
whereby improved contact life is achieved.
2. Circuit of claim 1 including means for adjusting the
7. In an electromagnetic relay pulsing circuit having a
power supplied to said relay coil.
15 relay coil, an interrupter in the power supply to said coil,
3. Circuit of claim 1 including means for indicating
said interrupter being alternately movable between nor
each pulsation of the circuit.
mally-open and normally-closed contacts, and capacitance‘
4. An improved electromagnetic relay pulsing circuit,
means in shunt around said coil, and improvement char
such circuit having a relay coil, a capacitance in shunt
acterized by reduced contact arcing which comprises: a
with said coil, power supply means and an interrupter 20 ?rst discharge path including a low resistance connected
armature in said circuit, said interrupter armature being
to discharge said capacitance means through said normal
movable ‘between normally open and normallly closed
ly-open contact whereby .the portion of time when the
contacts, the circuit comprising in combination means
interrupter is engaged with the normally-closed contact
varying said power supply to produce pulses in the range
is controlled, and a second discharge path including a
of about 0.1 to about 607 cycles/sec, a low resistance path 25 high resistance bridged across the normally-closed contact
discharging the capacitance through said normally open
to permit the application of power from said power sup
contact whereby the portion of time when the armature
ply to said relay coil When the interrupter is in the nor
is engaged with the normally closed contact is controlled,
mally-open position to thereby provide rapid opening of
and a high resistance path bridged across the normally
the normally-closed contact and to increase contact pres
closed contact to provide rapid disengagement from the 30 sure at the normally-open contact.
normally closed contact, said high resistance path permit
ting the application of power from said power supply
References Cited in the ?le of this patent
means to said coil when said interrupter armature is in
the normally open position whereby contact pressure is
increased at the normally open contact.
35 2,307,576
De Groce _____________ .._ Ian. 5, 1943
5. In a circuit comprising a relay coil, an armature
Thompson et a1 _______ .. Nov. 27, 1951
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