US3699521A

US3699521A - Decoding system having plural frequency channels

Info

Publication number: US3699521A
Application number: US61209A
Authority: US
Inventors: J Donald Hughson
Original assignee: General Signal Corp
Current assignee: SPX Corp
Priority date: 1970-08-05
Filing date: 1970-08-05
Publication date: 1972-10-17
Anticipated expiration: 1989-10-17
Also published as: JPS5332124B1; BR7105050D0; CA941056A; FR2104031A5; NL7110829A; DE2139294A1; GB1334259A

Abstract

A vehicle control decoding system has been provided having a plurality of filters tuned to detect code rates for selectively actuating output relays. The decoding system includes first checking means controlled by the outputs of the filters for delivering an output in accordance with only the most restrictive code rate output of the filters and a second checking means governed by the output of the first checking means and contacts of the relays for manifesting that only one of the relays is energized at a time.

Description

United States Patent Fl LTER 8. AMP- LIFI ER Hughson [4 1 Oct. 17, 1972 [54] DECODING SYSTEM HAVING PLURAL 3,302,113 1/1967 Clay ..340/17l A FREQUENCY CHANNELS 3,396,370 8/1968 Agnew ..340/ 171 X 72 l t D ld h 1 or J mm Hug Macedon N Y Primary Examiner-Harold l. Pitts AS81811; g g" N Y Corporation, Attorney-Harold S. Wynn and Milton E. Kleinman 0c ester, a 22 Filed: Aug. 5, i970 [57] ABSTRACT [2]] App]. NOJ 61,209 A vehicle control decoding system has been provided having a plurality of filters tuned to detect code rates for selectively actuating output relays. The decoding [52] 1.1.8. C1. ..340/171 A, 340/171 R system includes first checking means controlled by the F112;; ..A04q1/45 outputs of the filters for delivering an output in 1 "340/171 A cordance with only the most restrictive code rate out- [56] R f Ct d put of the filters and a second checking means e erences governed by the output of the first checking means UNITED STATES PATENTS and contacts of the relays for manifesting that only 2 MI 551 12/1938 PH 340/171 A one of the relays is energized at a time.

lnney 2,784,393 3/1957 Schultheis ..340/171 A 5 Claims, 1 Drawing Figure TO VEHICLE BRAKE CONTROL 1 DECODING SYSTEM HAVING PLURAL FREQUENCY CHANNELS BACKGROUND OF INVENTION This'invention relates to decoding systems and in 5 virtually immune from danger of failure due to contact welding or a stuck armature due to high current surges. These relays by virtue of their ability to operate under such adverse conditions are manufactured by heavy duty components and are rather cumbersome in their construction. In addition to these factors their cost as compared to non-safety relays is greatly increased.

In order to save space, weight and reduce costs substantially, it would be desirable to use non-safety type relays having characteristics such that a failure would not result in an unsafe condition.

It is therefore an object of the present invention to provide an arrangement which substantially obviates one or more of the limitations and disadvantages of the described prior arrangements.

It is also another object-of the present invention to provide a fail-safe arrangement for controlling vital functions of a railroad vehicle without the use of safety relays.

SUMMARY or INVENTION There has been provided a decoding system having a plurality of filters tuned to detect code ratesfor selectively activating output'relays. The system comprises a first checking means controlled by outputs of the filters for delivering an output in accordance with only the most restrictive code rate output of the filters in case filters for a plurality of code rates should deliver outputs contemporaneously and a second checking means governed by the input of the first checking means and contacts of the relays for manifesting that only one of the relays is energized at a time.

For a better understanding of the present invention, together with other and further objects thereof, reference is bad to the following description taken in connection with the accompanying drawing, while its scope will be pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic diagram employing the apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 0 Code rates for associated ranges of vehicle speed;

namely, low, medium and high are coupled through the rails R to pick-up coils 11 carried on the vehicle such as the control car on a rapid transit system or a railway locomotive. The signals received by the coils 11 are transmitted to filter and amplifier apparatus 12 for filtering of all but a specific range of desired frequencies and amplification of the resultant signal. The signals are then coupled to a network of filters each tuned to an appropriate code rate frequency different from the others for discriminating one code rate from the others. Each rate filter includes an inductor L and an associated series connected capacitor C. It is to be understood that each LC combination shown in the drawing' is different from the other for purposes of discriminating one code rate from the other. An amplifier A is serially connected to the output of the filter and increases the output of the filter LC for driving its as sociated relay. The relays L, M and H are output relays for manifesting which of the respective low, medium and high code rate signals have been received and discriminated. This manifestation is represented by the energization of

associated contacts

13, 14 or 15, each coupled to a speed control apparatus (not shown), which in turn governs the operation of the vehicle. This is essentially what occurs when safety relays are used to govern the operation of the input contacts to the speed control apparatus. In the present system, however, the relays'L, M and H controlling the inputs to the

speed control

13, 14 and 15 respectively are not safety relays and a failure of any one of the relays would result in an unsafe condition.

A first checking circuit has been incorporated into the system in order to assure that only the most restrictive code rate output of the filters LC associated with its respective relay L, M or H may be delivered to an output. The output is used to drive all rate relay AR.

If a signal representative of a medium speed characteristic is transmitted and received through the pickup coils l1 and amplifier and filter 12, the LC combination associated with the relay M passes the signal and produces at-itsoutput, energy for activating the associated relay M through driver A. In addition to this, a lead from the input of the driver A is connected to a front contact 17 of the relay M. The energization of relay M as a result of the medium rate code signal passed by the associated LC combination and the signal present at the front contact of contact 17 is coupled through the lead to a back contact 16 of the relay L. The signal is then coupled through the driver A as sociated with all rate relay AR, which when energized by the signal, picks up contacts 19 and 20. If, for some reason, the relay L is also energized during this period, relay AR becomes deenergized because there is no low rate signal present at the output of the LC combination .associated with the relay L. On the other hand, if the relay H becomes energized during the same time when the relay M is energized, there is no effect on the all rate relay AR because the open back contact 17 of relay M is irresponsive to the condition of relay H.

This first checking circuit including the

contacts

16, 17 and 18 of relays L, M and H provide one phase of the security necessary for rendering the system failsafe.

A second checking circuit includes the contacts 21 associated with relay L, 22 and 23 for relay M, 24 and 25 for relay H and 19 and 20 as previously described for relay AR.

In describing the first checking circuit, it was noted that the energization of two relays simultaneously may go undetected if a code rate appears at the output of a filter LC having the most restrictive code rate of the two. Such a condition, while not unsafe in itself, might be unsafe with other possible failures. It is thus necessary to detect and correct the failure at the earliest possible time. Relay H might be in the energized position for a number of reasons, for example, a frozen or welded contact or possibly a malfunction in" the associated driver A which in turn could provide energy for holding the relay AR.

The second checking circuit, therefore, has for one of its purposes to detect when one or more of the relays L, M or H is energized at any one time. It can be seen that a path of energy for holding the check relay CR must be maintained at all times. This is required in order to maintain the contact 26 in a forward or closed position for maintaining the vehicle brake control (not shown) in a-standby condition. If the relay CR drops its contact 26, the brakes of the vehicle are automatically actuated. The resistor-capacitor combination RC across relay CR provides a slow release characteristic to the relay CR for permitting switching time of the other relay contacts of the system.

The drawing shows the vehicle in a stop position receiving no code rates from the wayside-Therefore, the relays L, M and H are deenergized and their associated contacts 21; 22, 23; and 24, 25 are all in the back contact positions. Energy is therefore supplied through the

back contacts

21, 23, 25 and back contact 20 of relay AR to maintain relay CR energized. If a medium speed code signal is received through the rails R and coupled through the coils 11 and amplifier and filter 12 to the'inputs of the filters LC, then the filter LC and driver A associated with relay M would provide a signal for energizing the relay and coupling a signal through from contact 17 and back contact 16 to energize relay AR. The

contacts

22 and 23 associated with the relay M are switched to the front position and the contacts 19 and 20 for relay AR are likewise switched. A path of energy is still maintained, however, for holding the relay CR energized. This path of energy is from energy plus back contact 21, front contact 23, back contact 24 and front contact 19 to the relay CR. If now a signal representative of a low speed code is received and the mid-range signal is removed, the relay M should be deenergized and relay L should pick up its contact 16. However, if some malfunction occurs such that relay M remains energized, an improper condition exists. The low rate signal coupled through front contact 16 of relay L will hold the relay AR energized because the most restrictive signal is present and is therefore transmitted for holding up the relay AR. However, since two relays L and M are simultaneously energized, the second checking circuit opens the energy path to relay CR namely closed front contact 21 and open contact 22.

A similar condition would exist if the relays M and H were also simultaneously energized or H and L, in addition, if the relays H and L were simultaneously energized and a high rate were being received, the closed front contact 16 of relay L would prevent energy from the high rate filter LC from being transmitted through relay is energized and closes front contact 17 providing an energy path through back contact 16 for energizing relay AR and its associated contacts 19 and 20. In addition to this, the

contacts

22 and 23 of relay M shift to the front position providing an energy path for the relay CR through back contact 21, front contact 23, back contact 24 and front contact 19 to CR. If, however, some malfunction occurs which causes the relay H to energize also, the path of energy to the relay CR is opened because the previously closed backcontact 24 shifts to the forward position and opens circuit to relay CR. On the other hand, if the relay L becomes energized simultaneously with the energization of relay M, the relay AR would drop out because of the opened back contact 16. This alone would be sufficient to drop the relay CR. However, the back contact 21 opens also providing a second open circuit to the relay CR.

The system of the present invention therefore provides for checking of the received code rate such that only the most restrictive code rate signal received is capable of energizing the all rate relay AR and the energization of which is used in a second checking circuit which provides for a check that the only one of the code rate relays L, M or H is energized at any one time.

While there has been described what is at present said to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made herein without departing from the invention, and it is therefore aimed in the appended claims to cover all such changes and modifications that fall within the true spirit and scope of the invention.

What is claimed is:

1. A vehicle control decoding system for selectively actuating output switching circuits in accordance with a plurality of coded input signals, comprising:

a first, second and third input signal included in the plurality of coded input signals with the first input signal corresponding to more restrictive vehicle operation than either the second and third input signal and the second input signal corresponding to more restrictive vehicle operation than the third input signal;

a first, second and third switching circuit responsive to said first, second and third input signal, respectively, for switching circuit signals in accordance with the status of said first, second and third input signals;

first checking means controlled by said first, second and third switching circuits for delivering an output in accordance with only a one of said first, second and third switching circuits that has been actuated and selected to correspond to one of said first, second and third input signals present that is related to the most restrictive vehicle operation;

second checking means controlled by said first, second and third switching circuits for delivering an output signal when at least two of said first, second and third switching circuits are actuated at the same time; and

interlock means connecting said first and second checking means so that said second checking means is activated by an output 'signalfrom said first checking means indicating that at least one of said first, second and third switching circuits has been actuated.

2. The decoding system of claim 1 wherein:

said first, second and third switching circuits each include a relay actuated by said first, second and third input signals; and

said first checking means includes a pair of frontposition and back-position relay contacts from the relays, in each of said first, second and third switching circuits, the front-position contacts of each pair of relay contacts coupled to corresponding input signals and the back-position contacts coupled to relay contacts in switching circuits related to successively less restrictive input signals than the input signals connected to the respective front-position contacts to provide the selected output signal from said first checking means to activate said interlock means.

3. The vehicle control decoding system of claim 2 wherein said interlock means includes an interlock relay coupled to the relays of said first, second and third switching circuits for actuating said interlock relay when any one of the relays in said first, second and third switching circuits are actuated by a corresponding one of said first, second and third input signals. 7

4. The vehicle control decoding system of claim 1 wherein:

said first, second and third switching circuits each include a relay actuated by said first, second and third input signalsv and contacts of each relay are interconnected so that only a single output signal is produced corresponding to the actuated one of said first, second and third switching circuits that is related to the most restrictive one of said first, second and third input signals present.

5. The vehicle control decoding system of claim 1 including a plurality of filters tuned to detect code rates for associated ranges of vehicle speed and said first, second and third input signals are produced by said filters.

Claims

1. A vehicle control decoding system for selectively actuating output switching circuits in accordance with a plurality of coded input signals, comprising: a first, second and third input signal included in the plurality of coded input signals with the first input signal corresponding to more restrictive vehicle operation than either the second and third input signal and the second input signal corresponding to more restrictive vehicle operation than the third input signal; a first, second and third switching circuit responsive to said first, second and third input signal, respectively, for switching circuit signals in accordance with the status of said first, second and third input signals; first checking means controlled by said first, second and third switching circuits for delivering an output in accordance with only a one of said first, second and third switching circuits that has been actuated and selected to correspond to one of said first, second and third input signals present that is related to the most restrictive vehicle operation; second checking means controlled by said first, second and third switching circuits for delivering an output signal when at least two of said first, second and third switching circuits are actuated at the same time; and interlock means connecting said first and second checking means so that said second checking means is activated by an output signal from said first checking means indicating that at least one of said first, second and third switching circuits has been actuated.

2. The decoding system of claim 1 wherein: said first, second and third switching circuits each include a relay actuated by said first, second and third input signals; and said first checking means includes a pair of front-position and back-position relay contacts from the relays, in each of said first, second and third switching circuits, the front-position contacts of each pair of relay contacts coupled to corresponding input signals and the back-position contacts coupled to relay contacts in switching circuits related to successively less restrictive input signals than the input signals connected to the respective front-position contacts to provide the selected output signal from said first checking means to activate said interlock means.

3. The vehicle control decoding system of claim 2 wherein said interlock means includes an interlock relay coupled to the relays of said first, second and third switching circuits for actuating said interlock relay when any one of the relays in said first, second and third switching circuits are actuated by a corresponding one of said first, second and third input signals.

4. The vehicle control decoding system of claim 1 wherein: said first, second and third switching circuits each include a relay actuated by said first, second and third input sigNals and contacts of each relay are interconnected so that only a single output signal is produced corresponding to the actuated one of said first, second and third switching circuits that is related to the most restrictive one of said first, second and third input signals present.