US2787756A

US2787756A - Electric control means

Info

Publication number: US2787756A
Application number: US270488A
Authority: US
Inventors: Feinte Henri
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-02-07
Filing date: 1952-02-07
Publication date: 1957-04-02
Anticipated expiration: 1974-04-02

Description

Ap 2, 1957 H. FEINTE ELECTRIC CONTROL. MEANS 2 Sheets-Sheet 1 Filed Feb. 7, 1952 g PRIOR ART April 2, 1957 FEINTE ELECTRIC CONTROL. MEANS 2 Sheets-Sheet 2 Filed Feb. 7, 1952 Mrzn TOR ATroR/YEY United States Patent ELECTRIC CG'NTROL MEANS HenrilFeinte, Laval, France Application February 7, 1952, Serial No. 270,488

1 Claim. (,Cl. 323-86) My present invention is in part a continuation. of my copending specification Ser. No. 87,712,. filed on. April 15, 1949, now abandoned. It has for its object a control system for the selective operation of one or a small number of electrical apparatuses out of a plurality of apparatuses, said system resorting to the well-known connections including a series of. resistances in parallel;

associated each with a stationary contact-piece while a. sliding elongated contact-piece is adapted to provide progressively the energization of the stationary contactpieces starting from one end of the line of said station'- ary' contact-pieces over a. supply of current so as to" short-circuit an increasing number of resistances, the sliding. elongated contact-piece being constituted. for in stance by a mass of mercury adapted: to extend over a variable number of." stationary contact-pieces. starting from one end of the series of such contact piec'es.

Now, according" to my invention, I obtain, through the novel: association oi L-type networks with a system of. the type referred to and including switches adapted to close corresponding short circuits in succession through the progression of any movable member, such as a column of mercury in? a tube or oi a train along its rails, the selective operation of. relays or the like apparatuses inserted in the series arms of the successive L networks. Such networks are well-known and their properties areresorted to in order to provide for a reduction underneath a predetermined threshold of the current feeding them, except one or a few networks fed by the last switch or switches that are being engaged by the movable member. The formulae of: calculation of such networks allow selecting the' value of the different imp'ed'- ances, whether those arranged in parallel or those arranged in series, or at the end of the line of networks,

i. e. the so-called iterative impedance's, in a manner" such that it is ossible to obtain: predetermined drops in" voltage that gradually decrease from one energized series impedance to the next, the short-circuited impedances having obviously no action on the relays or apparatuses to be controlled.

My present invention resorts to the modifications in the characteristic values of the currents flowing through successive series impedances of a chain or such L type networks when the chain: is fed through a varying number of its apices, each apex being constituted by the connection point between two successive series impedanees and the associated parallel impedance.

in order to obtain the desired selective operation, I resort to electric relays or apparatuses that are adapted to become operative as soon as the intensity flowing through them rises above a predetermined minimium value or threshold. When no current passes through them or when the intensity of current flowing through them is smaller than this threshold, the apparatus remains or becomes inoperative. Apparatusesof this kind are constituted by relays adaptedto be energized only for a predetermined number of ampere-turns, incandescent bulbs that are illuminated only for a drop in voltage Patented. Apr. 2, 195 7 "ice above a predetermined value and, generally speaking, all devices used for signalling or relaying purposes and operating' above a predetermined intensity oficurre'nt,

My invention covers a method and means for the selec' tive operation of one or more of a plurality of appa ratuses provided with such a threshold operation, which apparatuses are inserted in the series arms of the chain, fed through one or more of its apiceas, the distribution: of which is selected in accordance with the type of apparatuses to be considered while the Values or the imped ances of the chain are selected in a manner such that the currents passing through the different series impedances rise above the thresholds of the corresponding apparatuses only in a predetermined number of' networks or cells lyingv to one side of the last apex or ap'i'ces that arefed, according to the number of apparatuses to be simultaneously operated through such an apex or apices.

The execution of my invention is thus provided chiefly by a chain of impedances constituted by a number of L cells wherein the series impedances' are constituted at least partly by the apparatuses that are to be oper atcd selectively while the free ends of the parallel impedances are connected on one hand with one terminal of a common supply of current and on the other hand with one of a succession of stationary contact-pieces that are thus electrically connected with the" apices of the chain for cooperation with a slidingly movable contact-piece connected with the other terminal of' said supply and engaging, a variable number of stationary contact-pieces. The sliding contact-piece may thus cooperate with all the stationary contact-pieces between one: end of the chain and a predetermined selected contact-piece, or else with a group of successive contact-pieces, or again with one, two or more contact-pieces, in which latter case the contact-pieces cooperating with the sliding contact-piece are separated from: one: another by a constant or variable number of intermediary contact-pieces;

The values of the impedances' of the chain are chosen in a manner such as to allow the selective high energization' of one or more of the apparatuses inserted in one or more of the series arms of the ll. network's, said apparatuses being each directly connected with an apex corresponding with a contact-piece engaged by the sliding contact so as to be fed with a higher electric energy when the apex corresponding to the apparatus considered is about to be reached or is the last to be reached" by the moving sliding-contact-piece. nently closed circuit is used, it is possible' to make the drop potential. between the terminals of aseries impedance provide for control without it being necessary to take into account the fact that the last contact-piece cooperating with the sliding contact piece corresponds withv one end of the series impedance or with the other end.

It is also possible to cut out the" presence of any controlled. apparatus from a certain: number of series impedances and again it is possible to insert further appa ratuses in the parallel impedances of the chain, for' instance when it is desired for an apparatus to become operative as soon and as long as the sliding contact engages a contact-piece corresponding to the apex to be'-- When a perma Fig. 6 is a modified diagram of a control device indicating the degree of filling of a boiler with the simultaneous operation of two apparatuses.

Fig. 7 is a wiring diagram provided in accordance with the invention for the control of the signalling means on a railway line.

Turning to Figs. 1 and 2, the arrangements illustrated provide for the operation of meters recording the modifications in the level of a mercury column 1 inside a tube 2 respectively, in accordance with known art and with the present invention.

In accordance with the previously known arrangements as illustrated in Fig. 1, the tube 2 filled with a mass of mercury 1 contains a number of contact-pieces 3 at different levels inside said tube. Each of said contact-pieces is connected with one of the terminals of an electromagnetic meter illustrated in the present case by a winding 4. The second terminal of each meter is connected through a return wire 5 with one of the terminals of a supply of energy 6, the other terminal of which is connected with a contact-piece 7 in permanent electric contacting relationship with the mercury column, a protective switch operating periodically and illustrated diagrammatically at 8 being inserted between the supply 6 and the contact-piece 7. This arrangement provides for the operation, each time the switch 9 closes, of all the meters 4 simultaneously, the contact-pieces 3 associated with which are bathed by the mercury column at the time considered, whereby each of said meters receives an impulse.

If it is supposed the switch 8 closes once per second, it is sufiicient, in order to ascertain how long the level of the mercury column has remained between two successive stages corresponding to two successive contact-pieces, to deduct from the value indicated by the meter connected with the lower contact-piece the value indicated by the meter connected with the upper contact-piece considered.

The problem to be solved in the case considered consists in designing the arrangement in a manner such that each meter may indicate the number of seconds during which the level of the liquid reaches a predetermined position i. e. during which it lies between two successive superposed contact-pieces.

The prior arrangement as illustrated in Fig. 1 shows also a drawback from a mechanical standpoint by reason of the fact that the meter corresponding to the lowermost level operates permanently and is thereby submitted to a heavy duty. This leads to the risk of errors without it being possible to ascertain the magnitude of such errors because it is impossible to determine whether all the meters have actually worked uninterruptedly during the period of recording.

Now, my improved arrangement as illustrated in Fig. 2 includes also a number of contact-pieces 10a, 10b, 100, etc., that are distributed throughout the height of the tube 1 in the same manner as the contact-pieces 3 in Fig. 1. Similarly, a predetermined number of impulse meters 11a, 11b, 110, etc., are provided, but in contradistinction with the prior arrangement of Fig. 1 they are inserted between the ends of the parallel impedances 12a, 12b, 12.5, the free ends of which are connected with one terminal of a source of electrical energy 14.

In a preferred embodiment, the meters may assume a. resistance of 500 ohms and they may operate when fed by a current of 40 milliamperes passing through them while they return to inoperativeness when the current drops down to 28 milliamp eres.

As disclosed, these meters are inserted in the series arms of the successive L type networks of the chain, which networks include also the parallel impedances 12a, 12b, 120, etc. The apices of this chain of impedances are connected with the corresponding contact-pieces, 10a, 10b, 10c, etc. The parallel impedances 12a, 12b, 12c have e. g. a resistance of 500 ohms, while the impedance 13 forming the iterative impedance at the end of the chain has a resistance of 309 ohms. These values are ascertained through the well-known formulas governing such L type networks. The second terminal of the supply of energy 14 is connected again through a contact-piece 15 with the foot of the mercury column with the insertion, between said contact-piece 15 and last mentioned terminal, of a periodically operating switch illustrated diagrammatically at 16. The source of energy 14 is chosen so as to produce a permanent voltage of 36 volts.

It is apparent that any of the meters 11, having its terminalsconnected with two contact-pieces that are both in contact with the mercury column, is short-circuited and produces no impulse when the periodically operating switch 16 closes. The meter 11d of Fig. 2 for which only the lower corresponding contact-piece 10d is in contact with the mercury column while the next highest contactpiece 102 is free from such a contact, is fed in the case considered with the comparatively large current while the meter 11c and the following meters that lie higher than the meter 112 are fed with currents, the intensities of which decrease for meters at increasingly high locations. It is therefore apparent that when the contact-piece 16 is closed, only the meter 11d is fed with current of an intensity that is sufiicient for it to be operative while the higher meters 11c and 11] remain inoperative by reason of the passage of weak currents that are underneath the threshold intensity of 28 milliamperes.

It should be remarked that it is possible to check whether the meters are operating reliably because the total number of impulses recorded should be equal to the number of times the periodically operated switch 16 closes, each closing of last mentioned switch providing for one impulse and only one, said impulse being provided by the meter inserted in the impedance that at the moment considered is inserted between two contact-pieces 10 of which one is bathed and the other is not bathed by the mercury column.

In the further embodiment illustrated by way of example in Fig. 3, the general wiring diagram is similar in its principle to that illustrated in Fig. 2 and is adapted for controlling a pump feeding a container 17, which latter is to be filled with water or the like conductive liquid. The conductive wall of the container carries two contact pieces 19 and 20 that are carried in insulating sleeves. The contact-piece 19 is located in register with the minimum level of the liquid, beneath which the liquid level should not sink. The contact-piece 20 registers with the maximum level beyond which the liquid should not rise. The L networks includes series arms constituted by a relay 21 which is inserted in series between an illuminating bulb 22 and its associated impedance 23 on one hand and a second incandescent bulb 25 and its associated impedance 25, on the other hand. The chain is completed through the parallel impedances 26a, 26b, and the terminal iterative impedance 27.

The apex of the chain that corresponds to the impedance 26a is connected with the contact-piece 19 and the apex corresponding to the impedance 26b is connected with the contact-piece 20. The free ends of the

impedances

26a, 26b and 27 are connected with one terminal of the supply of energy 28, the other end of which is grounded through the body of the container at the point 29 forming part of a first network and connected with the end of the series impedance constituted by the incandescent bulb 2 4 and the associated impedance 25. The relay 21 provides for the energization of a motor 30 controlling the pump. The operation of the wiring diagram illustrated is the same as in the case of Fig. 2; it is timed with reference to the operation of the relay 21 in a manner such that said relay closes a switch in the circuit of the motor 30 when the level of liquid lies between the contact pieces 19 and 26 so that said relay may receive a sufliciently' high intensity for it to operate. As soon as the contact-piece 20 is bathed by the liquid, the relay 21 is short-circuited, the corresponding switch opens and deenergizes the motor 30.

The values of the

auxiliary impedances

23 and 25 are calculated in a manner such that the total impedance of each

incandescent bulb

22 or 24 together with that of the associated

impedance

23 or 25 is equal to the impedance of the relay 21 and it is also such that the drop in voltage inside the bulb 22 is not sufficient for illuminating said bulb when the connection is provided through the contact-piece alone. As soon in fact as the liquid level lies between the contact-pieces 19 and 20 and the motor 30 is energized, the intensity of the current passing through the bulb 22 and the associated impedance 23 is not sufli cient for said bulb to be illuminated; in contradistinction, when the liquid level reaches the contact-piece 20, the relay 21 is short-circuited and opens so that the bulb 22 receives a sutficient electrical energy and is illuminated to show the highest allowed liquid level is reached. If, on the other hand, the liquid level drops underneath the contact-piece 19 by reason of any faulty operation, for instance it the pump sucks no liquid any more or if substantial leakages appear in the container, the bulb 24 is illuminated so as to show an abnormal liquid level and an abnormal operation have been reached; at the same time, the relay 21 that is fed with current of an intensity that is less than the operative value opens so that the motor is no longer operative. From this moment onwards, the whole arrangement is completely stopped and can be started again only through manual interference. This cuts out any abnormal operation such as that wherein the pump rotates without sucking any liquid.

Fig. 4 shows the same wiring diagram and the same references as in Fig. 3 with the difference that the parallel impedance 26 is constituted by a relay 31 which is inserted exactly in the same manner as the meters 4 in the case of Fig. l, i. e. in accordance with the prior arrangemerits, the operation being exactly the same when current is passing through the contact-piece 19. This arrangement may serve for controlling the opening of slide valves whenever the level of liquid rises above the minimum level. The slide valves being thus open close when for any reason whatever, the level of liquid drops underneath said minimum level.

The arrangement illustrated in Fig. 5 shows the wiring diagram of a control system for the feeding of a boiler.

The water chamber in the boiler is shown diagrammatically at 32. In the walls of said Water chamber are provided insulated contact-

pieces

33, 34, 35, 36, 37 and 38. This arangement provides in direct relationship with the location of the varying water level in the chamber the execution of the following steps:

(a) The operation of an acoustic alarm and the opening of a-release of exhaust slide valve when the water level rises beyond a predetermined maximum location.

(b) The illumination of a signal while the water level is normal.

(0) The starting of a pump having a small capacity for equilibrating the losses when the boiler lies under pressure without any steam being used.

(d) The starting of a medium capacity pump which should be operated in the case of normal utilization of the steam.

(e) The starting of a pump of large capacity in order to make up for a large consumption of steam.

(f) .The operation of an accoustic alarm device simultaneously with the closing of the slide valve controlling the feeding of the boiler when, for any reason whatever, the water level drops underneath the minimum safety level.

The contact-pieces 33 to 38 are distributed throughout the height of the boiler and are located at different levels corresponding to the control of the different operations. The chain includes a relay 39 providing for the control of the operation of the acoustic alarm device and for the closing of the fuel slide valve, a relay 40 controlling the operation of the motor driving the pump of large capacity, arelay 41 controlling the motor driving the pump of medium capacity, a relay 42 controlling the motor driving the pump of small capacity, an incandescent bulb 43 mounted in series with an associated impedance 44, which incandescent bulb is operative as an indicator when the water level is normal and a relay 45 controlling the acoustic alarm device and the exhaust-controlling slide valve.

The L networks are completed by the

parallel impedances

46a, 46b, 46c, 46d, 46c and by the iterative impedance 47. The free ends of the parallel impedances and of the iterative impedance are connected through a return wire 48 with one terminal of a source of energy 49, the other terminal of which is grounded through the wall of the water chamber 32. The values of the impedances 46 and of the impedance 47 are calculated in accordance with the usual formulae of L networks, taking into account the impedances of the relays and of the signalling means such as 45 and also the maximum and minimum intensities that are required for starting the relays and for closing them in a manner such that when the circuit is closed between the liquid in the water chamber 32 and one or more of the contact-pieces 33 to 38, only the first relay beyond the contact-piece immediately below the water level receives suflicient current for ensuring its operation.

Consequently, it is necessary to provide, in accordance with the location of the water level in the chamber of the container 32, a closing of the circuit between the body of the grounded container 32 and the difierent contact-pieces 33 to 38 including all those contact-pieces that are bathed by the liquid and no other.

By reason of this insertion of the relays in the chain, the apices of which are connected with different contactpieces, only the relay or the signalling means lying be tween the last contact-piece bathed by the liquid and the first contact-piece that is not bathed receives a current of sufiicient intensity for it to become operative.

Supposing the water level lies above the uppermost contact-piece 38, the relay 45 alone is energized and the corresponding acoustic alarm device becomes operative and warns of the arrangement operating in some faulty manner; at the same time, the exhaust slide valve opens and produces consequently a lowering of the water level until said exhaust slide valve closes again upon the water level dropping underneath the contact-piece 38. At this moment, the incandescent bulb 48 is fed in its turn with' a sufiiciently high current and becomes illuminated, which indicates the water level is normal. When however the water level sinks by reason of losses of fluid underneath the next contact-piece 37, the signalling bulb 43 that receives no more current of suificient intensity is extinguished and the relay 42 forming the next series impedance closes and produces operation of the pump of low capacity. It further and larger losses of water are produced through a large consumption of steam or the like reasons and the water level sinks further so that the contact-piece 36 is no longer bathed by the liquid, the relay41 closes and starts the pump of medium capac ity into operation. Normally, such a pump of medium capacity is sufiicient for ensuring a normal feed of water into the boiler. If, for any reason whatever, the consumption of water rises above normal, the water level drops underneath the next contact-piece 35. At this moment, the relay 40 closes while the deenergized relay 41 opens and this produces the operation of the pump of large capacity while the pump .of medium capacity stops operation. Upon still further dropping of the water level, as a consequence of some leakage or by reason of a .failure of the pump, said level sinking then underneath the contact-pieceStl, .the next relay 3,9 closes, theacoustic alarm device isstarted and the-fuel slide valve closes. .Erom this moment onwards the whole arrangement is at a standstill and .can .be started again .only by hand. This prevents cold water from entering .a superheated boiler which might lead to serious damage.

In the modification illustrated in iliig. .6, the water chamber is again shown at :32 while the contact-pieces 50 are providedina mannersimilar to thecontact pieces 33 to 38 of .Fig. 5. -In this embodiment, .the following operations .may be obtained in succession.

(a) The operation ofan :acoustic signal-and the opening of an exhaust slide valve whenever the water level rises above a maximumlevel;

.(b) The operation of .a =signal when :the :upper limit of normal water levelis reached;

The simultaneous operation of two signals corresponding .to the upper and lower limits .allowed -for the water level, in case the water level .actually lies between .two predetermined limits;

(d) The .operation .of .the signal corresponding to the lower-limit of the water .leveh-together =with.the starting of a pumpof small capacity when the water level in the chamber .32 is suflicient but sinks -as -a consequence of losses underneath an intermediary level between the extreme levels allowed;

(e) Theoperationofa pump of small capacity .and .of a pump of medium capacity when, .as .asconseguence of the consumption of water, .the water .level sinks under its normal lowerlimit;

(f) The operation of two pumps of mediumcapacity when, .for any .reason whatever, the water level sinks too much;

(g) The operation ofa signal indicating a lack-of water together with theclosing of the fuel slide valve whenever the water level .sinks'underneath a .critical value, whereby a reduction in the production of steam provides again a return to normal level.

(h) Lastly, in case the operation of the medium capacity pump is.not sufiicient formaintainingthe water-level while the production of steam is completely cut-out and if .the .water level continues sinking asa consequence-of a leakage, all the water feeding means are closed while the signalcorresponding to a lack of watercontinues operating and the fuel slide valve isclosedand-the .whole arrangement comes simultaneously to a standstill.

in the caseof thevabovementioned stages of operation, itlis to bevremarked that, .in the majorityof cases ,two groups of apparatuses operates simultaneously, each group being connected so .as to operate selectively with the preceding apparatus .or with the following apparatus.

In order -.to achieve this .result, the successive series impedancesare constituted by the ;r elays ,51, :the incandescent bulbs 52 associated inseries each with -an auxiliary impedance 53 andinoperative impedances 54 while the paralle'ljimpedances 55 connected with the connecting pointsprovided between the successiveseries impedances form with the latter thedesired .L networks. The chain ofL networksis fedhya supply of energy 56 the terrriinalsof whichare connected respectively with the free ends oi'the impedances .55 and with the grounded-mass of the container 3.2.

In .order to provide the -desired successsion of the above-listed steps of operation, the chain of L typenetworks includesin series-an'inopera'tive impedance 54 inserted'betweenthe second terminal of thersupply 56 and the connecting point or apex of the L network that is connected with the lowermost contact-piece 50, a first relay 51 controlling the signal corresponding tolack of water and to the closing of the slide valve, a second relay 51 controlling the motor dr ng he pump of medium capac ty, a third relay 51 providing for the operation of a second pump of medium capacity, .a tqurth relay .51 controlling the motqrdriving the pump o small p y. an incandescent bu 52 f rming th signal c r responding .to the lower limit allowed for the normal water level, a second incandescent .bulb 52 providing .a signal corresponding to the upper limit of normal water level, .an inoperative impedance S4 and a last relay 51 forminga signal corresponding to a water "level that is too high and to the operation of theexhaustslide-valve. Taking into account the fact that the values worked out vfor the impedances are .such that, as soon as a contact-piece 59 is bathed .by the liquid and the following contact-piece lies above the water level, the two impedances extend.- ing in series above the :apex connected with the vfirst mentioned liquid-bathed contact-piece, are the only ones to be fed with a current of sufiicient intensity either for energizing-the relayscorresponding theretoorelse for illuminating the incandescent .bulb inserted in the correspondingmemberof the chain, itiis consequentlycbvious that the .abovedefined conditions of operation are satisfied.

Figs. 7 shows two railroad -rails.60..-61,forming a track over which one, twoor more trains aremoving. The sliding contacgpiece .is constituted by the actual train running overrthe track. .lt.-is supposed -,that,the train runs only in one direction, which direction is in the example considered-that from .the right handside to the left hand side of Fig. -7. The .rail .6-1 is adapted throughout its length to be energizedthroughconnection with one terminal .of a source of energy, .intthe case illustratedthe pcsiti-veterminal. ,TheJail-considered from right toleft includes a

successionof sections

61a, 61b, 61c, 61d, the lengths of which are definedin accordance with the ;requirements-of trafiic. The single sections are insulated electricallywith reference to one another and the rails in each section are :electrically interconnected so that each section maybe energized throughout its length. Each end of a sectionisconnected with the end of the next section through a polarised relay-.62. The relays 62 are all similar-to one another and are designated by the reference numbers 62a, 62b, 620 etc., and they assume for instance a resistance-of 200 ohms-each. Their threshold of operation-lies in the vicinity of milliamperes and itis ascertained that with a sufficient safety margin, their operation is perfectly reliable for milliamperes while their inoperativeness is also reliably obtained for 65 millianiperes. They are adapted to provide for the passage of a current of 250 milliamperes without any substantial heat being evolved. vSuch relays are stable and are .easy to execute. Each of these relays is associated with a signal through an arrangement providing for :the signals, operating with the conventional red and green lights, to remain red whilethe green light is extinguished or dimmed whenever the relay is inoperative. When the relay is actuated and the contact-piece thereon is shifted towards the right handside of Fig. 7,,the r ed light is extinguished or dimmedin its turn while the green light is.illuminated orreturned to normal intensity which shows that the track is free. The contact-piece on the .left hand side of Fig. 7 is not used in the arrangement considered.

It has been believed unnecessary to overload the drawing and description with the coutrolrmeans for the sig nal, 1still less-with the actual signal. :The latter needs not be located exactly at the point at which two-sections meet and it can stand at ;a predetermined distancethereof in conformity with themequirements of traflic. Itmay also be connected with other--signals such-toninstance as signals for half-track or -stop signals.

Alongside of the track, there-extendsyawire 63.connected with the positive terminal of the supply of .current ,fi4producing a 50-voltcurrent. Eachgsection of the rail 61 is separatelyconnected with the wire.63 :through aresistance 64 of :3 00-;Ql1ms. {Eheseyresistances zarerdesigna'ted individually by the reference numbers 6411,6411, 64c, 64d, etc., and form with the impedances of the relays 61 a chain of networks.

It may be assumed that the resistance of the lateral wire 63 and also that of the track rails may be neglected. If, however, this is not the case, it is possible to make up for this by inserting aplurality of auxiliary supplies of current in parallel with the first mentioned supply at different points of the track or else these further resistances are taken into account in the calculation of the wiring diagram.

In the case of the example considered, it is necessary that the iterative or terminal resistance 65 of the network should assume a value of 65 ohms.

1st casefidupposing there is no train running over the track, all the relays are inoperative and all the signals are closed.

2nd cam-There is a single train on the track; said 'train running for instance entirely over the section ole,

we will consider to the front thereof two L-networks and the same number to the rear of the train. The relay 62b behind the train is fed with a current of 137 milliamperes in a direction such as will urge the movable contactpiece against the stationary contact-piece to the left thereof. The signal remains thus closed. The relay 62a is fed with only 62 milliamperes and remains inoperative so that the corresponding signal also remains closed. As the train continues its travel over the section 61c, the

relay 62s is fed with 137 milliamperes in a direction such as will urge the corresponding contact piece to the right, which opens the signal controlled by said relay. The relay 62d, in contradistinction, is fed only with 62 milliamperes and remains inoperative so that the corresponding signal closed. As readily apparent, the conditions of operation for 62s and the subsequent relays are similar.

The signal corresponding to the relay 620 is now open and the train may enter the section 61d. When its forward end enters the next section 61d While its rear end is still on the section 610, the relay 620 is short-circuited and becomes inoperative so that the corresponding signal closes behind the driver. At the same time, the relay 62d opens its signal and permits the entrance of the train into the section 610. When the last axle of the train has entered the section era, the contact-piece of the relay 620 is energiz d in a direction opposed to its prior energization so that its contact-piece is urged towards the left and the corresponding signal remains closed.

Thus if only one train is running over the track, all the signals in front of it are closed except one. When the train progresses from one section to the next, it provides for the opening of a single signal in front of it and it may thus travel through the entire track without stopping.

I will now disclose the operation of the signal when the track is occupied by a second train.

3rd case-There are two trains on the track considered. Having elucidated the problem of the presence of two trains on the same track, this solves immediately the problem of operation for any number of trains simultaneously occupying the track.

A train having entered the section 61d and assuming in accordance with a hypothetical supposition, that there is another train ahead of it in the section 612, the relay 62d is short-circuited and is therefore inoperative and provides for the closing of the corresponding signal. This closes the entrance into the section file and protects the train in last-mentioned section. It may be objected that the last axle of one train has perhaps already entered the section 61c when the first axle of the next train has on tered the section 61d, which would unavoidably lead to a collision. However, this objection does not hold, in the first place because, as already disclosed hereinabove, the signal is not necessarily located located at the meeting point between two sections and moreover because no train is so to speak set over a section and the arrangement defined provides the necessary safety with a completely free intermediary section as will appear from the fol lowing disclosure:

in actual practice, the train lying in the section 61a cannot move any further while the track in front of the train in the section die is free and last-mentioned train may enter the next section elf. When the first axle of the train has entered said section 61!, the relay 62a is sh'ort-circuited and becomes inoperative so that the corresponding signal closes. The train that is in section 61d has therefore in front of it two closed signals as the relays 62d and 622 are both short-c-ircuited and consequently inoperative, and therefore said first train is constrained to remain in the section did.

When the last axle of the running train enters the sec tion 61 the relay 622 will remain inoperative as it is fed with only 62.5 milliamperes and the corresponding signal remains closed. At the same time, the relay 62s is also fed with 62.5 milliamperes and the corresponding signal remains closed. The train held fast in the section'fld cannot continue running as there are two closed signals in front of it.

When the train in the section 61] continues moving, this produces a novel position for the relays and the signals which I will now examine. When the front axle enters the section dig, the relay 62] becomes inoperative and the corresponding signal closes. Furthermore, there is no modification in the relays 62s or 62d nor in the signals associated therewith. The running train is thus protected by three closed signals. When the last carriage of the running train enters the said track section 61g, the relay 62f is fed with milliamperes and shifts its contact-piece towards the left so as to keep the corresponding signal closed. The relay 626 receives no current and remains closed. The relay 62d is fed with 100 milliamperes in the operative direction so that its contact-piece is shifted towards the right so as to re-open the track for the train lying in the section did. This latter train may therefore enter the section 61c.

As concerns this latter case, it is possible to show that when the number of sections and'of relays between the trains increases:

1. The relays lying between two trains are fed with current of constant direction and the intensity of which ranges between 100 and 137 milliamperes, which latter value is reached only when the track is completely free and for such a range ofintensities the corresponding signals open in fncnt of any train and close when it has passed.

2. The current in the relays preceding and following the relays considered increases from 0 to 62 milliamperes which latter value is only reached when the train is very far away, the corresponding signals being closed for such intensities flowing throughthe relays.

3. The current passing through the relays other than those considered hitherto is still weaker so that said relays are all inoperative and the corresponding signals are closed.

It is possible to develop these facts in a similar manner for any number of trains on the track and there is found that this leads to a system wherein:

1. In the absence of any train on the track, all the signals are permanently closed.

2. The trains control the opening of the track, said opening being provided automatically and only for one signal at a time as soon as the track is free. If, on the contrary, the track is occupied, the train is automatically stopped.

3. All the trains are protected by at least two signals while the protected minimum distance between the rear of one train and the front of the next train corresponds to an entire section increased by the dilference between the controlling point and the actual signal. The maximum distance that is protected includes two sections plus the distance between the point of abutment between two sections and the actual location of the signal controlled through the relay connected across said point of abutment.

4. Safety is also obtained where there is no current flowing through the relays or when an unexpected breaking appears at any point of the connections. The only possible causes of a disturbance as far as safety is concerned are constituted by an abnormal increase in the voltage of the supply or else by a short-circuit affecting the resistances 64. It is sufiicient to resort to very simple protective steps in order to remove these two objectionable possibilities.

In the first place, for instance, it is possible to use as a supply a storage battery or a system of dry cells. As to the second cause of failure, it is possible to give the resistances 64 a suitable shape and a suitable location, for instance they may be subdivided into a plurality of elements that are at a distance from one another am. that are suitably protected.

In the above disclosure, 1 have not considered how the contact-pieces on the left hand side of the relays of Fig. 7 may be used nor how it is possible to return them into their inoperative position. Now these contact-pieces may serve for the connection of complementary signals, acoustic signals, alarm devices or the like arrangements, for instance arrangements providing a breaking of the current in such or such a section, and they may also serve for any purpose that may be useful.

I may mention as an example that the left hand contact-pieces may serve for controlling further signals and for the protection of trains running in the opposite direction over the track, i. e. from the left to the right of Fig. 7.

It is apparent that the problem of traffic on a single track or on a double track may be solved in a similar manner. These problems are also similar to the problems of the movement of a plurality of lifts in a common shaft.

What I claim is:

In an electrical control means comprising a plurality of electrical apparatus, selected from a group consisting of relays, signals, meters, valves and pumps, connected for operation and interruption of operation at least one at a time in sequence depending on the direction of movement of a movable contact means, the said plurality of electrical apparatus being connected in series, a plurality of taps insulated from each other and spaced along the line of movement of said contact means, the said contact means having electrical connection with a terminal of a source of electrical current at one end of said line of movement of said contact means, each of the connecting means between said apparatus having electrical connection with one of said taps for operation in said sequence, each of said connecting means between the apparatus having electrical connections with an impedance, and each impedance having electrical connection with a common lead connected to the other terminal of said source of electrical current.

References Cited in the file of this patent UNITED STATES PATENTS 1,613,422 Wegel Jan. 4, 1927 2,462,076 Dryden Feb. 22, 1949 2,566,260 Thomson Aug. 28, 1951 2,645,749 Labino et al. July 14, 1953 FOREIGN PATENTS 511,067 Great Britain Aug. 14, 1939 917,077 Germany Aug. 23, 1954