US2061770A - Remote control apparatus - Google Patents

Description

Patented Nov. 24, 193% UNH'ELEE .;;i;

REMOTE CONTROL APPARATUS Arthur P. .llackel, Swissvale, Pa., assignor' to Ihe Union Switch & Signal Company, Swissvale,

Pa. a corporation of Pennsylvania Application October 30. 1934, Serial No. 750,657

3 Claims.

My invention relates to remote control apparatus, and particularly to apparatus for use in connection with a remote control system in which a line circuit is employed for signaling by code between a control ofllce and remote stations and in which a portion at least of the line circuit is included in a cable.

The principal object of my invention resides in the provision of means for overcoming or nulliiying certain effects due to storage of energy in a cable and detrimental to the proper operation of a remote control system, so that the extent of territory and the number of stations that can be controlled over a cable line circuit may be increased.

I will describe three forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 illustrates diagrammatically, a typical line circuit for a remote control system including one form of apparatus of my invention. 2 illustrates diagrammatically the line circuits for a remote control system employing three line wires and including another form of the apparatus of my invention. Fig. 3 illustrates a modified form of a portion of the apparatus of Fig. 1.

Similar reference characters refer to similar parts in each of the views.

Referring to the drawing, Fig. 1 shows a line circuit employing a line control wire Y and a common return wire Z extending from a control ofiice, having a line relay OR and a transmitter relay OT, to a remote station, having a line relay R and a transmitter relay T. The line circuit may be traced from one terminal of the line battery LB, through current limiting resistor 6, line relay OR, contact 3 of relay OT, 'li'ne wire Y, relay R, contact 3 of relay T, common return wire Z, to the other terminal of line battery LB. As shown in the drawing, the two line conductors Y and Z are closely spaced to indicate that for a portion of their length at least, they are included together in a cable. As compared with an open wire line, the efiect of a cable is to greatly increase the capacity between conductors, this being of the order of one-tenth to two-tenths microfarad per mile in cables of the types usually employed. One effect of this increased capacity is to permit the flow of a transient charging current of a relatively high value when contact 3 at the ofiice is closed, so that relay OR will pick up in advance of relay R. A transient discharge current similar in form and value will flow when contact 3 at the office is opened, causing relay R to remain energized for a short time after relay OR releases.

While I have, for simplicity, shown but a single field station, it is to be understood that generally the remote control systems of which my inven tion may be applied will include a plurality of stations each having a line relay R and these line relays will be connected in series in the line circuit. When the line circuit includes a plurality of stations, the storage of energy in the line capacity will, of course, be greater because of the additional voltage that must be applied to the line circuit to operate the additional line relays. Furthermore, in remote control systems of the type referred to the same line circuit is usually employed for signaling in both directions, so that there will be in general a plurality of independently controlled transmitter relays, each having a contact 3 in the line circuit. It may readily happen that the two contacts 3 at the opposite ends of the line may be opened at about the same time, leaving the portion of the line circuit including the cable fully charged, and if, as is usually the case, the conductance between conductors Y and Z is negligible, the charge may remain stored in the cable for a time without appreciable loss. If now relay T releases while relay OT is energized, a transient discharge current will flow through relay R to pick up and release this relay without operating relay OR. If, as is usually the case, the remote control system for its proper operation requires relays OR and R to operate repeatedly in unison, this transient current may thus produce an additional relay operation at one end of the line only, and thus interfere with proper operation.

A transient current quite similar in form may at times cause relay OR at the office to pick up and release without operating relay R at the station. This will be the case if relay OT picks up to disconnect battery LB, and relay T picks up subsequently, after the cable has discharged through relay R, the transient current in this instance being that which fiows from battery LB to charge the line when relay OT releases.

In Fig. l, I have illustrated code receiving apparatus controlled by the line relays diagrammatically by a rectangle, it being understood that in general the remote control system will include some sort of stepping apparatus, such for example, as a chain of counting relays. One' form of code receiving apparatus which will operate in the manner intended, is disclosed and claimed in an application for Letters Patent of the United States, Serial No. 373,67 5, filed by L. V.

Lewis, on June 25, 1929, for Remote controlling apparatus, and is described in a book entitled Centralized Traific Control SystemTime Code Scheme, Manual No. 502, dated September 1931, and published by The Union Switch & Signal Company, Swissvale, Pennsylvania. To illustrate my present invention, however, it is suflicient to point out merely that when a line relay such as OR is operated, a circuit for controlling a code receiver will become closed. One such circuit may be traced from one terminal B of a local source of energy, front contact 5 of relay OR to a wire I leading to the code receiver, the circuit being completed over Wire l8 leading from the code receiver to the other terminal C to the same source of energy. When relay OR is deenergized, another circuit for controlling the code receiver will become closed, which is similar to that traced except that it includes back contact 5 of relay OR and wire '5.

To protect the code receivers against false operation due to momentary pick-up of the line relay as a result of a transient impulse due to the cable capacity, I provide a repeating relay, such as OP, having a circuit which may be traced from one terminal B of the local source of energy over back contact of relay OR, relay OP, to the other terminal C of the same source, so that relay OP will pick up each time relay R releases and will release each time relay OR picks up. The release of relay OP, however, will be retarded somewhat by reason of the asymmetric unit II connected in multiple with relay OP which provides a discharge path for the inductive energy of the relay. It follows, therefore, that each time relay OR picks up, front contact I2 of relay OP will remain closed for a brief time interval and the energization of wire I which is normally effected over back contact 5 of relay OR will be maintained over front contacts 5 and i2 and the energization of wire l over front contact 5 will be delayed until relay OP releases, this time being made somewhat greater than the time the line relay will remain picked up on the transient current due to cable capacity, so that wire I is not energized during this transient current time and only becomes energized when the line circuit is closed and relay OR is energized for a longer period in accordance with its intended operation.

As shown in the drawing, a similar relay P at the station controls circuits leading from the front contact 5 of relay R to wires l and l of the code receiver at the station in precisely the same manner.

In considering the operation of the apparatus of my invention, as illustrated in Fig. 1, it may be assumed that the line circuit is closed, that relays OR and R are energized, and that relays T and OT are each adapted to transmit codes of long and short impulses by repeatedly interrupting the line. If it happens that the two transmitter relays pick up at about the same time, the line will be opened at both ends so that relays OR and R will release at substantially the same time, each energizing wire l of its respective receiver. Relays OP and P will then become energized and pick up due to the closing of back contacts 4 of relays OR and R, respectively. If relay T releases first, the energy stored in the capacity of the cable will discharge through relay R, and this relay will be energized by a transient impulse of current to cause it to pick up to close its front contact 5 for a short time period somewhat less than the release time of relay P and to then release to close contact 5 before relay P releases. Contact I! of relay P will therefore remain in its picked-up position and wire I will not become energized by the operation of relay R due to the transient current, which therefore will have no effect whatever upon the code receiver. When relay OT releases and closes contact 3, relay OR will pick up on the rapidly increasing transient current comprising the charging current of the cable, but will remain picked up due to the more slowly increasing line current flowing through relays OR and R, which latter current Will cause relay R to pick up. The closed circuit periods of the code are of a predetermined length and are so adjusted that relays OP and P will release during each closed circuit line impulse to effect the energization of wires i, so that the code receivers will be operated in a normal manner.

Since with a given line circuit it is readily possible to determine the duration of the transient currents, it is evident, therefore, that relays P and OP may be adjusted to suit the characteristics of the line so that the initial portion of each line impulse may be discarded in the manner described so that the two code receivers Will be operated properly step by step in unison by their corresponding line relays and additional operations of one or the other of the line relays by transient currents due to cable capacity will be without effect.

In Fig. 3, I have shown circuits which may be substituted for the circuits associated with relays OP and P of Fig. 1 to illustrate a modified form of the apparatus of my invention. In Fig. 3 relay P is a slow releasing code repeating relay which picks up when relay R releases and closes its front contact i2 to energize wire 7 leading to the code receiver. When relay R picks up relay P remains picked up for a period slightly greater than the duration of a transient impulse and then releases to close its back contact 52 to energize Wire I. If however, relay R is energized momentarily contact IE will remain in its pickedup position and wire I will not become energized. It is evident, therefore, that in the arrangement of Fig. 3 contact l2 controlling the code receiver is non-responsive to the initial portions of the code impulses repeated by the line relay and that this modified form of my apparatus will likewise nullify the effect of transient impulses upon the code receivers.

In Fig. 2, I have shown the line circuits for a remote control system which is known as the Circuit Code system and which is disclosed in a patent application for improvements in Remote control systems, Serial No. 533,380, filed May 18, 1931, by C. S. Snavely, A. B. Miller and R. H. 'Iunell, and is described in a book entitled Centralized Traffic Control System-Circuit Code Scheme, Manual No. 501, dated April 1931, and published by The Union Switch 8; Signal Conn pany, Swissvale Pennsylvania. This system employs two line wires X and Y and a common return wire Z and has two line circuits each of which includes a line relay and transmitter contact at the oiiice and at the station and is like the line circuit of the system of Fig. 1. Each line circuit however, includes contacts of the additional transmitter relays 'IZ and OTZ, which serve to open both line circuits simultaneously. In this system, each code comprises a sequence of code elements designated X. Y or Z, characterized by the opening of one line circuit or the other or both. Another characteristic of the circuit code system is that the transmitter relays at a station that is receiving a code are Operated locally by their associated line relays to hold the line circuits open for a brief period on each step of the code to check or delay the operation of the distant transmitter until the code element is properly registered at the receiving station. It therefore follows that in this system the line circuit will be opened at both ends on each step and the hereinbefore described transient operation of the line relays may occur during any element of the code. As will be clear from Fig. 2 of the drawing, the code receivers in the circuit code system are controlled by the line relays in such a way as to energize one of the wires IX, 8Y or 92, as the case may be, when one or the other or both line relays become deenergized. The code receiver in the form illustrated in the above-mentioned application includes a slow release line check relay which in the case of the station receiver shown at the right in my Fig. 2 is energized over a circuit including a connection from contact l of relay RY to wire 2. To apply my invention to the system I connect contact l of relay RY to my code repeating relay P and then energize wire 2 by front contact [3 of relay P. When receiving a Y or a Z element of a code relay RY will be deenergized and a circuit may be traced from terminal B of the local source of current, back contacts and 1 of relay RY, relay P to the other terminal C of the same source. When receiving an X element of a code, relay RY will be energized but relay RX will be released, and a circuit may be traced from terminal B, front contact 5 of relay RY, back contact 5 of relay RX, front contact 4 of relay RY, relay P to terminal C, so that relay P will be energized when either relay RX or RY is released, and will be released when both RX and RY are energized. The code receiver also has a wire I which is energized over front contacts 5 of relays RX and RY, and in the circuit for energizing wire l, I include back contact l2 of relay P for same purpose of preventing a response of the receiver unless the line circuits remain closed for more than a predetermined time just as in the corresponding circuit already described in connection with Fig. 1. Relay P in Fig. 2 is likewise provided with an asymmetric unit H to retard its release in the same way as in Fig. 1. The circuits for the oifice receiver shown at the left in Fig. 2 differ from those at the station only in that a contact IQ on relay OM is included in the circuit of asymmetric unit ii. In this system, the energization of wire 5 controls the rate of progression of the stepping apparatus, and the addition of the relays P and OP not only slows down the speed of operation as is desirable when the system is used on a cable line, but these relays are arranged so that the operation of a transmitting station is retarded to a somewhat greater extent than that of a receiving station. To attain this end the asymmetric unit l 8 connected across the relay OP at the office is controlled over a front contact Hi of a master relay OM, which relay is energized when sending and deenergized when receiving, and relay OP is also provided with a copper ferrule or the like so as to be slightly slow releasing when its asymmetric unit it is disconnected. The arrangement .is such that when sending from the ofiice to the station, relay OM will be energized and relay OP will release more slowly than relay P at the station, while when the station is sending to the office, relay P at the station will release more slowly than relay OP at the office, thereby providing an additional time factor to insure that the ofiice and station remain in synchronism when the system is operated over a cable line. Since in Fig. 2, each of the line circuits is quite similar to the single line circuit of Fig. 1, it will be clear that the effect of a momentary pickup of either of the line relays due to a transient impulse will be nullified in the same way as in Fig. 1, because relays P and OP in Fig. 2 will be adjusted to hold their back contacts open for a time interval of which the minimum value is sufilcient to prevent energizing wire 8 when a line relay picks up on a transient impulse due to cable capacity.

It follows therefore that in the system of Fig. 2, the relays P and OP will regulate the speed of the transmitting station so as to slow down the speed of transmission by an amount which may be determined according to the characteristics of the line circuits so as to insure that two code receivers will be operated properly step by step in unison by their corresponding line relays, and the initial portion of each line impulse being discarded so that the effect of transient currents due to cable capacity will be nullified, even though these currents are of sufiicient value and duration to operate the linev relays.

Although I have herein shown and described only three forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a remote control system, a line circuit having a portion included in a cable, a transmitter contact at one point in said line circuit for repeatedly connecting a source of energy to said line circuit to produce a code, a second contact at another point in said line circuit operable independently of said first contact to produce a code, a portion at least of said cable being located between said two points, a line relay responsive to said codes and included in said line circuit adjacent said second contact, said line relay being adapted to pick up momentarily due to transient current resulting from the discharge of the energy stored in said cable after said first contact opens if the second contact then becomes closed, a repeating relay, an energizing circuit for said repeating relay including a back contact of said line relay, 2. code receiver having two control circuits adapted to be closed alternately and repeatedly in accordance with the codes delivered by said line relay, means for closing one receiver control circuit comprising a back contact of said line relay, and means for closing the other receiver control circuit comprising in series a front contact of said line relay and a back contact of said repeating relay.

2. In a remote control system provided with a code receiver, a normally closed line circuit including a line relay, a transmitting relay for repeatedly interrupting said line circuit to operate said line relay in accordance with a code, a repeating relay, means controlled by the line relay for energizing the repeating relay each time said line relay releases, a first circuit for controlling said receiver, means for closing said first circuit including a back contact of said line relay, a second circuit for controlling said receiver, and means for closing said second circuit, including a front contact of said line relay and a back contact of said repeating relay.

3. In a remote control system provided with a code receiver, a plurality of normally closed line circuits each including a source of energy and having a portion included in a cable, a plurality of transmitting relays including a group at each end of the cable for repeatedly opening one 01' more of the line circuits to produce a code, a line relay in. each line circuit controlled by said transmitter relays, said line relays being adapted to pick up momentarily on the transient currents due to energy storage in said cable resulting from the operation of said contacts, means controlled by said line relays for controlling said receiver, comprising a repeating relay, means for energizing ARTHUR P. J ACKEL.

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