close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2135530

код для вставки
Nov. ,s, 1938.‘
2,135,530
W. H. REICHARD
TRACK CIRCUIT FOR RAILROADS
7 Filed May '26, 1934
S
lq_______'__________l
m
.
(r)
IINVE TO
w. A
)
"44m’
?y ATTORNEY
2,135,53e
Patented Nov. 8, 1938
PATENT OFFICE
2,135,530
TRACK CIRCUIT FOR RAILROADS"
Wade H. Rei'chard, Rochester,v N. Y., assignor to
General Railway Signal’ Company, Rochester,
N. Y,
Application May 26,. 1934,. Serial No.. 727,691.
11' Claims.‘ (Cl. 246-41)"
Thisjinvention relates in general. to track. cir
cuits vsuch asused inrailway signaling practice
and has more particular referencetomeans. for.
automatically. discriminating between current.
changes in :the, track circuit due. tothe. occupied.
condition' of. the . track and- due. to. leakage. cur
rents resulting frompoor ballast: conditions.
In railway operation it‘ is quite. essential that
the. usual track relay connectedacross the track
110‘: sectionat. oneend of: a. signaling block be su?i~
ciently energized when the blockv is» unoccupied.
to. pick upand holduprwith certainty. It-is like
wise essential that the. occupancy. of the track
featuresof. theinvention will appear as the de
scription progresses, reference. being made to the
accompanying. drawing. showing by way of ex
ample-.oneform. which the invention may assume.
The. Single ?gure. diagrammatically illustrates 5
one form of the present invention applied to a
singlestretch of track.
Apparatus-Referring to- the drawing, a sec
tion of railway track including rails l is shown
separated from; the adjacent track sections by 10
insulated jointsZ. Atrackbattery IB and a lim
iting resistance R. are shown‘ connected to the
trackrails atthe right-hand end of the illustrated
track section.
As. typical-of-the control exercised by the track
relay
that
it
will
bepositivelyreleased.
For
ex-'
15?
ample, in the usual track circuitsif the normal relay, asemaphore signal SG is illustrated at the
holding currenttis. too~high, shunting may not be. left handend-of the. track section. A track relay
effective todrop the. relay and‘ if the normal hold--~ T, havingtwocoils is‘ illustrated, the control of
ing current is so low-7 that shunting will be more which’. will be. explained. in detail. A Pliotron or
positive it is. possible that at timestheholding ampli?er: tube R0 of any well known type is used,
and‘ as illustrated, is adaptedto control, by means
current may. be insumcient.
Taking theabove intoiconsiderationlit will be of. the voltage generated in. the secondary of
seen that the usual variation -in>ballast resistance transformer TR, the current for operating select
encounteredin practice, .dueprimarily tochanges ing relay. IS.
Associated withPliotron RC is theusual plate
in
weather conditions, may operate to interfere
25
source of current which may be, a battery 2B
with the proper operation of the’ track relay un
less some means is provided for discriminating andthe usual filament‘.- source: of current which
between changes due to ballast resistance and may be abattery A; Bias. resistor BR is adjust
ably connectedlto thegrid. circuit of the ampli?er
track occupancy.
in
order toprovide a normal biasto the in-put of
Asthe ballast resistance. increases, the leakage
30
section will so effectively shunt. or condition. the
current between‘ the rails. decreases so‘ that the
voltage across the terminals of the. track relay
connected to the track circuit increases; Con-
versely, as therballast resistance decreases,» ballast
leakage increases- and the terminal voltage- at the
relay decreases.
The relay current will vary. over a considerable
range and ‘cover a range at times which will pre-4
vent proper response of the relayeunder‘ occupied
v or unoccupied conditions of'the track section.
It is proposed in accordance with this inven
tion to-provide means, associated. with. the track
relay for discriminating, or detecting a‘ change
due to track occupancy and. unoccupancy' and.v
45 changes due to leakage currents caused by varia
tion in ballast resistance between thelrails ofv the:
track. In. accordance. with: the present» invention
it is proposed to improve theshunting e?iciency'
of'the trackcircuit and for this purpose. a; dis
r 5.0
, criminating arrangement 'is‘vincluded-in thecir
cuit of the track relay which discriminates be-'
tween a slow change intrack. shunt due to track‘
ballast and'a rapid change in‘. track shuntdueto
train . occupancy. .
55..
Further objects, purposes and. characteristic
theetube-for. a purpose that will .be later. described.
Slow actingselecting relays2S and 38 are pro
vided and these relays in cooperation with relay
IS-insertresistances IR, 2Rand BB. in the track
circuit under certain conditions-in a manner and
for a purpose that .will be explained in detail.
Normal conditions.-—With the circuit in its nor
malicondition as illustrated in the ?gure, track
relay T is normally picked up over a circuit ex
tendingfromthe (——) terminal of battery lB, re
sistance R, lower track. rail; lower winding and
upper winding of relay T in series, primary wind
ing of transformer TR,.front contacts ll, l2 and
i3 of relays. IS, 28 and 3S respectively and upper
track railjto the (+) terminallofbattery IB. The
constants.of.the described energizing circuit for
relayv T‘areof such'a value that su?icient current
flowsunder the worst ballast conditions (maxi
mum‘leakage betweenv track rails) to maintain
the contacts oi'relay T' picked up. The best bal 50
last conditions. (minimum leakage between track
rails) allows more. current to?ow over the above
described circuit‘. including relay T which of
course will‘maint'ain. its-contactsin their picked
up. positions.
2
2,135,530
Any change in current ?ow over the above de
inserted in the track relay circuit relays 2S and
3S may be omitted. When the selecting relays
scribed circuit takes place through the primary
winding of transformer TR but such a change
due to a change in ballast conditions takes: place
insert enough resistance in the circuit to drop re
lay Ta stick circuit is provided topreve'nt other’
selector relays being dropped, which circuit ex
tends from (+), back contact I 5 of relay T, front
contact I‘! and winding of relay 2S, to (—). The
quite slowly, so that there is no appreciable effect
on the secondary winding of transformer TR due
to such a change.
-
-
Adjustable bias resistor BB is so adjusted that
stick circuit is also e?ective to stick relay 3S over
the grid of ampli?er RC is normally sufficiently
a'circuit including its front contact I8 and its
positive with respect to the ?lament that sur?
winding, to (—).
cient current ?ows from the (+) terminal of bat
tery 2B, winding of relay IS, plate ?lament cir
cuit of the ampli?er and resistor BR to the (—)
terminal of battery 23, for maintaining relay IS
in its picked up condition. Since slow changes in
the track circuit current ?ow have no appreciable
effect on the grid circuit of ampli?er RC, this
bias is maintained substantially constant so that
relay IS is not affected by such changes.
20
Relay 2S is normally energized over a circuit
extending from (-|‘-) ;_front contact I4 of relay IS
and winding of relay 28, to (-—). Relay 3S is nor
mally energized over a circuit extending from
(+), front contact I5 of relay 2S and winding of
relay 38, to (—). 'With relays IS,‘ 2S and 3S
picked up, resistances IR, 2R and 3R are short
relay.
30
Track occupancy.—When the illustrated‘track
section is occupied the shunt across thetrack
rails, due to the wheels‘and, axles of the train,
causes a sudden decrease in the current ?owing
through the windings of relay '1'. This sudden
decrease inthe current flow through the circuit
including the primary winding’ of transformer TR,
which is in series with the track relay windings,
sets up» a potential across the secondary Winding
of transformer TR in such a direction that the
terminal connected to the grid of ampli?er RC'
becomes more negative with respect to the ?la
ment to such an extent that the current flow
through the plate circuit of the ampli?er is re
duced to a value which causes relay IS to drop its
contacts. Even though thisrpotential is only mo
mentary, relay IS has time to drop its contact-s
and after the grid circuit returns to its normal
‘state, with normal current flowing through the
plate circuit of the vacuum tube, this current
is insu?icient to pick up relay IS after it has
~ dropped its contacts. This is due'to the fact that
the pick up current'for the relay is considerably
higher than its holding current.
The dropping of front contact II removes; the
cuits of signal SG or for any other purpose re
~
quired by the usual practice in connection with
track relay circuits. Front contact 22 of relay 25
SS is not shown connected to any circuit but this '
contact is included to indicate that another se
lecting relay can be provided when desired and‘
connected to front contact 22 of relay 3S in a
similar manner to. which relay 3S is connected to 30
front contact I5 of relay 2S. _
.
I
Track 'unoccupcmcu-When' the ‘train leaves
the track section, the quick removal of the shunt
across the'track railscauses a sudden increase in
current ?ow through the track circuit including
the primary winding of transformer TR andthe
windings of the track relay in series, This sud
den increase in current ?ow sets up a potential
across the secondary winding of the transformer
in an opposite sense to thatpreviously explained
so that the grid of ampli?er RC
7
7 ,more'
becomes
positive with respect tothe ?lament. This'posi
tive potential on the grid'permits su?i'cient cur
rent to flow through the plate ?lament, circuit
for picking up relay IS. ~Relay IS removes re
sistor IR from the track circuit and closes a cir
cuit at its front contact I4 for picking up relay.
2S. Relay 2S removes resistor 2R from the track
circuit and, closes a circuit at its front contact I5
for picking up relay is. Relay 3Sremoves re-V
sistor 3R from the track circuit. It will be under 50'
stood that in the event that'relay 3S or 28 were
not dropped under the previous condition, then'
when the track becomes unoccupied ‘relay IS will
shunt from resistor IR so that this resistor is
inserted in the circuit. of relay T. This further
pick up to remove resistor IR which under this ,
reduces the currentc?ow through the windings, of
With relays IS, 2S and 3S picked up, the cir
relay
when
60 Relay
tion.
T so that'it has less holding power than
the track rails were shunted by the train.
T may or may not release under thiscondi
If it does not release within a predeter
mined time, relay 2S will drop its contacts be
cause front contact I4 of relay lS deenergizes the
65
10
after which those relays (if any) which were not
released will be stuck up through a back, contact 15
of the track relay.i Since the stick circuits of
the 2S and 3S relays are opened at their own
front contacts, after the track relay is dropped I
the selector relays are not againpicked up until
the track becomes unoccupied as will be described. 20
Contact 2| of relay T and contact 3I of relay
IS in series may be used to control the signal cir
15
circuited at front contacts II, I2 and I3 so that
they are not included in the circuit of the ‘track
>
It will thus be observed that relays IS, 28 and
3S function to sequentially insert resistance in
the circuit of the track’ relay until it releases,
winding of relay 2S. Relay 2S inserts resistance
2R in the circuitincluding relay T, by dropping its
front contact I2. Relay’ '1' may or may not re
lease under this condition. If it does not re
lease after 'a predetermined interval of time, cre
lay SS is, dropped because its energizing circuit
conditionis the only one included.
7
cuits are in condition for maximum current flow ‘
through the windings of relay TV which causes "
this relay to be picked up; The circuits are now 60'
in normal condition.
It will be clear from the above description that,‘
this invention provides means whereby there is a' a -
positive discrimination between the track circuit '
conditions due to track occupancy and due to
ballast
leakage.
,
,_
'
_
s
r
'
.
The above rather speci?c description of one
form of the present invention has been given
solely by way of illustration and is not intended
is open at front contact I5 of relay 2S; .Relay3S
then inserts resistance 3R in the track relay cir
in any manner whatsoever in a limiting sense.
cuit by dropping its front contact I3. .
. It will be understood that additional selecting _
relays may be provided if required, or if 1 ,condi—
herein disclosed maybe embodied in ,manynther
organizations widely di?erent, from that illus
trated without .departingfrom, the spirit of the
75 tions are such that only one resistor“IR need be
It will be obvious that the general principles
invention as de?ned in the'followlng claims.
.
3
amass-o
‘1. "In 'a‘itrack circuit, an ‘insulated ‘section or
said ~energizinglcircu‘it supplying the 'in-put ‘cir
cuit-of saidithermionic device ‘with alnormal bias
track, 'a source of current connected?‘to said
track, a track relay "connected ‘to said track and
55
energized in slowly varying degrees in accord
ance with the slowly changing current values
due to variations in ballast resistance, the en
trance ‘of a ‘train into said section of track gpro
vducing a'rapid reduction 2in the current in ‘the
10 circuit ‘of said relay, and means responsive ‘only
to said rapid reduction of current for ‘sequen
tially-inserting resistance units in the circuit of
said relay until the resistance of the circuit in
cluding said relay has increased to a value where
15 said relay releases.
2. In a track circuit, in combination with an
insulated stretch of track, a source of current
connected across one end of said track, a track
relay connected across the other end of said
20 track, an energizing circuit for said track relay
including the track rails, a thermionic device, a
transformer having its primary winding con
nected in series with said track relay and its
secondary winding connected to the in-put cir
25 cuit of said thermionic device, a control relay
connected in the out-put circuit of said therm
ionic device, the resistance voltage drop across
a portion of said energizing circuit supplying
the in-put circuit of said thermionic device with
30 a normal bias which maintains said control relay
picked up irrespective of changes in the ballast
condition of said stretch of track, and‘ the volt
age induced in the secondary winding of said
transformer due to the entrance of a train into
35 said stretch of track being suf?cient to over
come said bias to cause said control relay to re
lease, and means responsive to the release of
said control relay for effecting a control of said
track relay.
3. In a track circuit, in combination with an
40
insulated stretch of track, a source of current
connected across one end of said track, a track
relay connected across the other end of said
track, an energizing circuit for said track relay
including the track rails, a thermionic device, a
45
transformer having its primary winding con
nected in series with said relay and its secondary
winding connected to the in-put circuit of said
thermionic device, a control relay connected in
the out-put circuit of said thermionic device,
the resistance voltage drop across a portion of
said energizing circuit supplying the in-put cir
cuit of said thermionic device with a normal bias
55
which maintains said control relay picked up ir
respective of changes in the ballast condition of
said stretch of track, the voltage induced in the
secondary winding of said transformer due to
the entrance of 'a train into said stretch of track
sufficiently changing said bias to cause said con
trol relay to release, and means controlled by
said control relay for gradually inserting resist—
ance in said track circuit until and only until
said track relay is released.
4. In a track circuit, in combination with an
65 insulated stretch of track, a source of current
connected across one end of said track, a track
relay connected across the other end of said
track, an energizing circuit for said track relay
including the track rails, a thermionic device, a
transformer having its primary winding con
70
nected in series with said relay and its second
ary winding connected to the in-put circuit of
said thermionic device, a control relay connected
to the out-put circuit of said thermionic device,
the resistance voltage drop across a portion of
75
which maintains said control relay picked up ir
respective of changes in =theiballast condition of
said {stretch of track,‘ the voltage induced in the
secondary winding of said-transformer due to the
entrance of a ‘train into said stretch of track
su?iciently' changing said bias to cause said con
trol relay *to release, means controlled by said
'control relay for ‘gradually ‘inserting’ resistance 10
in said track circuit until and only until said
‘track relay’is released, “and means controlled by
the ‘exit \ of the -tr'ain*'fromsaidstretch of track for
sufliciently changing said bias to cause said con
trol relay to pick up.
15
5. A track circuit comprising an insulated
track section; a track relay; a resistance nor
mally excluded from the circuit of said track
relay; discriminating means including a therm
ionic relay; means responsive to the occupancy 20
of said section for operating said discriminating
means; means responsive to the operation of
said discriminating means for including said re
sistance in the circuit of said track relay; and
means controlled by said track relay for con 25
trolling the amount of resistance included in its
circuit.
6. In a track circuit, an insulated section of
track, a source of current and a track relay con
nected to said track, a plurality of resistance 30
units, slow-acting means for slowly and sequen
tially inserting said resistance units in series
with said track relay until it releases, means in—
cluding an impulse actuated device for starting
the operation of said slow-acting means, and 35
means controlled by the release of said track re
lay for stopping the operation of said slow-acting
means.
7. In combination, a section of railway track,
a source of current connected across the rails of 40
said section, a relay receiving energy from the
rails of said section and responsive to the steady
value of current with which it is supplied, a
transformer also receiving energy from the rails
of said section, and means energized from said 45
transformer and responsive to a change in the
energization of the transformer occurring upon
the entrance of a train into said section for
decreasing the energization of said relay where
by said relay will release.
50
8. In combination, a section of railway track,
a source of current connected across the rails of
said section, a relay receiving energy from the
rails of said section and responsive to the steady
value of current with which it is supplied, a 55
transformer having a winding included in the
energizing circuit for said relay, and means en
ergized from a winding of said transformer and
responsive to a change in the energization of
the transformer occurring upon the entrance of 60
a train into said section for decreasing the ener
gization of said relay whereby said relay will
release.
9. In a track circuit for railroads, the com
bination with a section of railway track having 65
a track relay and a source of uni-directional
current connected thereto, an auxiliary relay
separate from said track relay and effective when
operated to decrease the current through said
track relay and thereby cause release of its ar 70
mature, and means including a transformer for
causing operation of said auxiliary relay in re
sponse to the relatively quick change in the
current in said track circuit caused by the
entrance of a train into said section.
75
2,155,530
'10.. A track circuit for railroads comprising, a
track relay, a source of unidirectionalcurrent
for energizing said track relay, an inductive de
vice, and means receiving energy from the track
circuit through said inductive device and oper
ating in responseto the relatively high rate of
change in the current in said track circuit pro
duced by the entranceof a train upon said track
circuit for decreasing the current through said
10 track relay and thereby causing release of its
armature.
11.‘ In combination, a section of railway track,
a source of current connected across the rails of
said section, a ?rst relay receiving energy from
the rails of said section and responsive to the
steady value of current with which it is vsupplied, V I
a second relay, means for controlling said second
relay in accordance with the-rate of change of 5'
current ?ow'in said ?rst relay when the value,
of current through said ?rst relay is quickly de
creased due to the entrance of a train into said
section, and means controlled by said second
relay for‘ decreasing the energization of said 10
?rst relay.
7
WAD/EV
s
>
.
BEI‘CI-IARDL
Документ
Категория
Без категории
Просмотров
0
Размер файла
633 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа