US2303723A - Time relay system - Google Patents

Description

Dec. l, 1942. E M, CLAYTQR 2,303,723

T IME RELAY SYSTEM Filed Jan. 27, 1959 2 Sheets-Sheet l Dec. 1, 1942. E. M. CLAYTOR 2,303,723

TIME RELAY SYSTEM Filed Jan. 27, 1939 '2 Sheets-Sheet 2 ADL/0577154:-

INVENTOR G4/YJ aff W Pj/ ATTORNEYA,

Patented Dec. 1,1942

UNITED STATES PATENT ori-ICE f TIlHE RELAY SYSTEM Edward M. Claytor, Anderson, Ind., assignorv to General Motors Corporation, Detroit, Mich., a corporation of Delaware v Application January 27, 1939, Serial No. 253,136

2 Claims.

This invention relates to time relays in which a main exciting coil is employed to produce flux causing attraction of the armature toward the core or stationary element of the magnetic cirinvention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodi ment of the present invention is clearly shown.

cuit, and in which a neutralizing coil producing 5 In the drawings: reverse flux is employed to counteract residual Fig. l is a wiring diagram oi an automobile magnetism in the magnetic circuit so that the stop and directional signal system including two armature will move away from the core and time relays embodying the present invention.

thereby control some other circuit. Fig. 2 is a diagram illustrating the operation Heretofore it has been the practice to excite of the time relay. the neutralizing coil continuously to reduce the Fig. 3 is a side view of the time relay partly in residual magnetism to zero. The time which section. elapses between the opening of the circuit to the Fig. 4 is a wiring diagram showing a. modied main coil and the separation of the armature form of the invention. from the core depends on the mass and character li Referring to Fig. 1, L designates a signal of the iron of the core and armature. The greatlight on the left front fender of an automobile. er the mass, the greater will be the lapse of time 2IL designates a direction signal located on the required for the decay of flux. left side of the rear of the automobile. 22L des- The chief aim and object of the present inignates a stop signal lamp also located on the vention is to provide a time relay in which the 20 left of the rear of the automobile. The signal required time delay can be obtained by the use lamps 2BR, 21R. and 22R. designate, respectively, of a relatively small mass of iron and in response the signal lamps which are located on the rightto a predetermined number of intermittent excihand side of the automobile and correspond retations of the neutralizing coil. In this way the spectively with 20L, ZIL and 221.'. 231. designates bulk and cost of the relay is materially reduced-, in its entirety the time relay for controlling the and greater variations in the magnetic properties. signal lamps on the left side of the car; and 23R. of the iron of the core and armature are prdesignates the time relay for controlling the missible. lamps on the right side ci the car. 24 desig Instead of using a large mass of iron, I can hates the blinker unit. 25 designates the signal obtain the desired time lag by the use of a relacontrol switch comprising a movable, resilient tively small mass of soft iron having relatively grounded contact member 26 engageable either low residual magnetism. Instead of using a conwithstationary contact 21 to effect operation of Y tinuously excited neutralizing coil of relatively signals. indicating a turn to the left, or with a great m. m. f., I obtain the lag in reduction of contact-.28 to effect operation of signals indicatresidual flux to zero, by using an intermittently ing a turn to the right. 29 designates a stoplight excited neutralizing coil of relatively small magswitch comprising a movable member 3G engage netomotive force by means of which the residual able with contacts 3l and 32. Switch 29 may@ llux is reduced in stages, the number of which be operated directly by the brake pedal or it will be dependent upon the magnetomotive force may be a pressure fluidA operated switch where a ofthe coil and the lapse of time between succes lo hydraulic brake system is used. sive excitations. The blinker unit 24 which may be of any One of the ways in which my novel time relay conventional form comprises terminals d and l may be used is in a turn signalling system for with which normally engaged contacts 42 and an automobile. In an automobile turn signalling 43 are respectively connected. These contacte system a blinker relay has frequently been used 45 are intermittently opened by the energization of to cause the direction indicating lights to burn a magnet coil 44 which is grounded at o5. intermittently to give a flashing signal. When Storage battery 35 is grounded at and is my time relay is used in such a system, it operconnected by wire 3l with the time relays ISL atesnconjunction with the blinker to determine and 23R and by wire 38 with the stop light the length of time the blinker operates, and the switch 29. Each oi the timer relays 231. or E3B. blinker is so connected with the neutralizing coil includes a relatively soft iron magnetic circuit of the time relay that the time relay opens the comprising an L-shaped member 5E, a core 5! circuit of the signal after a predetermined numattached to member Sil by a screw 52, and an ber of flashes of the signal lamp.. armature 53 hingedly connected with the l...4

Further objects and advantages oi' the present 55 member all by means comprising non-magnetic able hinge plates 54 and 55 attached respectively to amature 53 and member 50. Plate 54 carries a stud 56 which passes loosely through a hole 51 in the plate 55. Stud 56 carries a cross pin 58 and a washer 59. A spring 60 surrounds stud 56 and is located between the washer 59 and the plate 55. Spring 60 is compressed so that it tends to urge the adjacent ends of the hinge plates 54 and 55 closer together thereby tending to separate the armature 53 from the core 5|. The core 5| is surrounded by a main relay energizing coil 6| and a neutralizing coll 62. The armature 53 insulatingly supports movable contacts 63 and 65 engageable respectively with stationary contacts 64 and 66. As shown in Fig. 1, relay contacts 65 and 66 are normally closed and contacts 63 and 64 are normally open. In the normal position of the relay, its armature 53 is separated from the core 5|. In the operating position of the relay the armature 53 is against the core 5| as shown in Fig. 3; and contacts 63 and 64 are engaged while contacts 65 and 66 are separated.

Contacts 64 of time relays 23L and 23R are connected by wire 10. Wire 1| connects coil 6| of relay 23R. with contact 28 of signal control switch 25. Wire 12 connects the magnet coil 6| of relay 23L with contact 21 of signal control switch 25. Wire 13 connects the contacts 63 of the time relays 23L and 23R. Wire 13 is connected by wire 14 with blinker terminal 40. Movable contacts 65 of relays 23L and 23R are connected by wire 15. Wire 15 is connected by vWire 16 with blinker terminal 4|. Wire 16 is connected with the. two neutralizing coils 62 of relays 23L and 23R which are connected in series between wire 16 and ground 11. Contact 66 of relay 23L is connected with wire 80 from which wires 8|, 82 and 83 branch off to lamps 20L, 2|L and 22R respectively. Contact 66 of relay 23R is connected with wire 84 from which branch off wires 85, 86 and 81 leading to lamps 2DR, 2|R and 22L respectively. Lamps 22R, and 22L are grounded. Lamps 20L, 2DR, 2|L and 2|R are connected with wire 16 to which wire 15 is connected.

To indicate a left turn, the switch is operated to close contacts 26 and 21 thereby connecting magnet coil 6| of relay 23L with the battery through the following circuit: battery 35, wire 31, coil 6|, wire 12, contacts 21 and 26, blade 26a and ground return to battery. The energization of magnet coil 6| causescontacts 63 and 64 of time relay 23L to be closed and the contacts 65 and 66 thereof to beseparated as shown in Fig. 3. When this occurs, current will flow from the battery through the blinker to the left turn signal lamps 20L and 2|L through the following circuit: battery 35, wire 31, contacts 64 and 63 of relay 23L, wire 14, blinker contacts 42, 43, wire 16, lamps 20L and 2|L, wire 80, wire 83, stop lamp 22R and ground return to battery. Current will also flow to stop lamp 22L from wire 16, through :vire 15 contacts 65, 66 of time relay 23R., wire 81, stop lamp 22L and ground. Thus, when a turn signal lamp is connected, both stop lamps will also be connected, but the stop signal lamp on the sarne side of the vehicle as the selected turn signal lamp will burn the brighter, because it is energized in parallel with the turn signal lampy while the dimmer stopsignal lamp is in series with the selected turn signal lamp. Lamps 20L and 2 IL will be illuminated to indicate the left turn at front and rear of the to the change about to be made. The blinker 24 will operate intermittently' to separate contacts 42 and 43 through the operation of the magnet coil 44 to separate the contacts against the force of a contact closing spring not shown. Therefore, lamps 20L and 2 IL and both stop lamps are giving an intermittent flashing signal. This flashing signal is produced an instant following the closing of contacts 26 and 21 of switch 25 and will continue for a short period after these contacts have separated. Hence, it is not necessary for the operator to hold the switch blade 26a in contact closing position.

As stated before, the closing of contacts 26 and 21 causes magnet coil 6| of relay 23L to be energized. When this occurs, the armature 53 shown in Fig. 3 is caused to contact with the stationary magnetizable parts 50 and 5|. Due to residual magnetism in the relay iron, the armature 53 does not immediately separate from the parts 50 and 5| when contact 26 is separated from contact 21. There is a certain lag due to hysteresis producing a relatively slow decay in flux. This decay in ux is retarded to a predetermined eX- tent by the operation of neutralizing coil 62 which is energized intermittently by the blinker 24. The blinker 24 may be constructed and adjusted to cause a signal flash once every .5 to 1.5 seconds. The ltime relay may be constructed and adjusted to require a predetermined number of flashes to take place before the time relay separates contacts 63 and 64 and recloses contacts 65 and 66 as will be explained hereinafter. The time relay may be adjusted to require from 5 to 10 excitations of neutralizing coil 62 through the operation of the blinker 24 before the relay opens. If for example, the blinker 24 gives a flash every 1.5 seconds, and the time relay is constructed and adjusted to require 10 excitations of the neutralizing coil 22 before the relay opens, then the flashing will continue for approximately 15 seconds after a contact 26 of switch 25 is separated from contact 21. If blinker 24 is set for causing a flash every .5 second and the relay is constructed and adjusted to require 5 excitations of neutralizing coil 62 before the time relay opens, then the flashing will continue for 2.5 seconds after contacts 26 and 21 of switch 25 are separated. The period of 1'5 'secoridsmaybelonger than necessary for an automobile signal. However, these figures are given to show that the duration control by the time relay may be varied to suit'the requirements of the equipment in which the time relay is used.

To indicate a right turn, switch 25 is operated to close contacts 26 and 28 thereby energizing magnet coil 6| of the time relay 23R to effect the closing of contacts 63 and 64 and the opening of contacts 65 and 66 thereof, while the contacts of relay 23L remain in the condition shown in Fig. 1. When this occurs, the right hand signal lamps will receive current from the battery through the following circuit: battery 35, wire 31, wire 10, contacts 64,and 63 of time relay 23R, wire 13, wire 14, blinker contacts 42 and 43, wire 16, lamps 2BR and 2|R, wire 84, wire 61, stop car and the stop lamps will act to call attention lamp 22L and ground return to battery. The right hand time relay 23R operates in conjunction with blinker 24 in the manner described with respect to left hand time relay 23L.

For the signal switch 25 having a blade 26a movable into two positions from a central position, one may use two push button switches connected in alternate circuits, one of which is used to indicate a left turn and the other a right turn.

These switches may be conventionally mounted on or adjacent a steering wheel of an automobile.

Obviously, when the left signal lamps 20L and ZIL are burning, the right signal lamps 2DR and ZIR do notA burn, because both terminals of each are subjected to the same potential as the wire 16, by means of the closed contacts 65, 66 and wire of the relay 23R. For the same reason the lamps L and 2lL do not burn when the signal lamp 2DR and 2|R are operating.

When the brake is applied, the brake switch 29 is closed to cause both stop lamps 22R and ZZL to be connected to the battery through the flasher 24.

I will now describe in more detail the operation of the time relays 23R and 23L. In Fig. 2 distance horizontally from the right of line y-y represents positive excitation and distance horizontally from the left of line y-y represents opposite or negative excitation. Distance vertically above the line .1J-rl: represents flux in a positive sense and distance vertically below the line :1r- 33 represents flux in the opposite or negative sense. Point O is the intersection of lines .'c-x and y-y. The curve a-b-c-d-a is the hysteresis loop of the time relay. Part a-b is the build-up of flux corresponding to excitation of the main coil 6I when the excitation is measured by the line o-b. The flux is represented by o. Assuming that at point b the magnet coil 6I is disconnected from the current source, the flux will die down slowly as indicated by line b-b' due to the effect of circulating eddy currents whose effect in turn opposes the decay of flux. Due to residual magnetism, there will be flux (t, 4although the excitation of coil 6| is zero. In order that the residual flux may be reduced to zero, 'it has been the practice to use a neutralizing coil which is continuously energized to the extent represented by line O-C. When a continuously energized neutralizing coil-is used, it is necessary to provide the relay with a large mass of iron of prescribed magnetic properties, otherwise the magnetism Would be reduced to zero in too short a time. I havediscovered that I can effect the same time delay through the use of an electromagnet having much less iron in its circuit, if I use a relatively weak neutralizing coil in contrast to a relatively strong energizing coll as used heretofore, and if I intermittently energize the neutralizing coil instead of continuously as heretofore. Therefore, instead of employing a neutralizing coil requiring excitation O--C, I use a smaller one requiring excitation O-C which does not reduce the residual flux from o1 to zero, but from ci to qbz. Then I disconnect the neutralizing coil 62 from the current source when the flux is at point l on the line b--c. The dying away of the negative excitation of coil 62 causes the flux to return along the line l--2. The next excitation of coil 62 causes the flux to die away along the line 2-3 which is below the line b-L Then the second disoonnec-f tion of the coil 62 from the current source results in a return of residual flux to the point 4 on the line yy. Then reenergization of coil 62 causes residual magnetism to follow the line 4 5 and deenergization of coil 62 causes the residual magnetism to return along the line 5 6. This process of demagnetizing continues until the residual magnetism is reduced to zero. Instead of the magnetism falling to zero at point C which would require the continuous excitation of neutralizing coil requiring C-O ampere turns which would produce demagnetism in a relatively short time, I am able to delay demagnetization through the intermittent excitation of the neutralizing: coil 62 requiring a relatively small number ofv ampere turns as represented by line C'O.k This effect is due to the fact that the residual magnetism is alternately opposed and then allowed to build up again as represented by the series of small hysteresis loops such as b'f-l-Z, 2-3-4, 4-5-6, etc. In other words, I provide cycles of magnetomotive force in opposition to residual flux which destroy the flux in steps, each step being represented'by a miniature hysteresis loop which reduces the original residual flux lower and lower until it has finally become zero. The diagram shows that sixr energizations of coil 62 will effect reduction of the flux to zero. Obviously, the number of intermittent excitations of coil 62 as represented by the small hysteresis loops, required to reduce the residual flux to zero can be made to vary according to the construction of the relay. Thus the time relay embodying my principle can be constructed to suit any sort of equipment in which itis possible to use a relay which can be made to control a circuit in response to a predetermined sequence of excitations of the neutralizing coil of the relay. For use with an automobile signalling system a relay which requires ve to ten intermittent excitations of-f'the neutralizing coil is satisfactory.

I have found that instead of using a relatively large mass of iron to provide the required time delay, I am able to obtain satisfactory vresults with a relatively small mass of iron. I find that it is unnecessary to be so careful about the grade of iron used as to its residual magnetism since I do not neutralize residual magnetism in one step, butin a series of small steps.

When using the relay in a circuit subjected to variable voltage, such as in an automobile electrical circuit in which the voltage may vary from 6 to 8.4 volts, it may be that the time of delay of the relay is too short when the voltage is increased. To obtain a longer time where the voltage is not constant, I may employ a short circuiting band of copper or other good conducting material around the core. This tends to stabilize the demagnetizing flux by giving a lower percentage change in demagnetizing flux than the percentage of change in voltage.

To summarize briefly, the principle of my invention is the reduction of residual flux to zero in a predetermined series of small steps as the result of intermittent excitation of a neutralizing coil of relatively low magnitude or ampere turns. The functions of the relay depend in part on the rate of decay of flux, the magnitude of the hysteresis loops, the frequency of the intermittent current impulses through the neutralizing coil and the duration of said current impulses. By using an intermittently operated neutralizing coil I am able to obtain a time delay as great as that heretofore obtained by use of a much larger relay having a relatively massive magnetic circuit and coils of much greater structural dimensions. Furthermore, I am able to control the duration of delay because it is responsive to a predetermined sequence of excitation of the neutralizing coil,

Fig. 4 is a wiring diagram of a circuit in which an adjustable frequency device is employed for controlling the neutralizing coil of the time relay so that the armature of the time relay will drop out a predetermined time after a controlling switch has been closed. The circuit to be con trolled includes a switch comprising contacts and |0|. Contact |00 is carried by the armature A of the time delay relay, the core of which is indicated by letter C. One leg of .the core is surrounded by the main exciting coil M and by the neutralizing c oil N. Coil M is in circuit with a switch S1 and a battery Bi.

The adjustable frequency device which controls the energization of the demagnetizing or neutralizing coil N comprises a magnet core |02 surrounded by an energizing winding |03. When this magnet is energized, an armature |04 is attracted from the position shown in Fig. 4 downwardly. Armature |04 is pivotally supported at |05 and is connected with a lever arm |05 which insulatingly supports a contact arm |01 carrying a contact |08, normally engaging a contact |09 attached to a resilient contact support ||0, the movement of which is obstructed by a stop pin The armature is connected also with a pendulum rod ||2 along which slides an adjustable pendulum bob ||3. The position of the bob ||3 on the rod I I2 determines the frequency of oscillation of the pendulum, armature |04 and contact supporting member |06. The neutralizing winding N and the magnet energizing coil |03 are connected together in parallel and each of these windings is connected in series with a battery B2, a switch Sz and the contacts |08 and |09 of the adjustable frequency device.

It is assumed that the circuit to be controlled is to be controlled by the closing of contacts |00 and |0|. Therefore, initially the Contact |00 is separated from contact |0| by upward movement of the armature A. into contact with the core C of the time relay. This upward movement is effected by the closing of switch S1 which causes current to flow from the current source B1 to the main exciting coil M. Swith S1 is only momentarily closed to cause armature A to engage the core C. Thereafter switch Si is opened. Residual magnetism in the core C maintains the armature A in the attracted position. The adjustable frequency device is set so that the contacts |0| and |00 of the circuit to be controlled will be engaged a predetermined time after the closing of the switch S2. The closing of the switch S2 causes current to flow through the demagnetizing winding N and also through the magnet coil |03 of the adjusting frequency device. The energization of coil |03 causes counterclockwise movement of the armature |04 thereby causing contact |08 to be separated from contact |09, thereby effecting oscillation of the rod ||2 and bob ||3 The oscillatory movement of the rod ||2 effects the intermittent closing of contacts |08 and |09 thereby effecting the inter-- mittent energization of the neutralizing coil N. After a predetermined number of intermittent excitations of the neutralizing coil N have taken place, the residual magnetism in the core O of the time delay relay will be completely neutralized and the armature A will descend by gravity carrying contact |00 into engagement with contact |0|. Since the release of the relay armature A depends on a predetermined nu'mber of impulses of excitations in the coil N, the period of oscillation of the adjustable frequency device will determine the lapse of time between the closing of the switch S2 and the dropping of the armature A.

' The system shown in Fig. 4 is adapted for use in a'ny device where it is desired to effect the operation of some electrically controlled device 9. predetermined time after the closing of a control switch. For example, it may be desirable to effect the detonation of an explosive charge a predetermined time after the closing of an electric circuit. In such case the contacts |00 and |0| would be in the circuit of the electrical means for detonating an explosive charge. The Contact |00 would be held separated from the contact |0| by momentarily exciting the relay magnet winding M by momentarily closing the switch S1. If the neutralizing winding N is effective after six intermittent excitations thereof to neutralize the residual magnetism in core C, and if the frequency device hasbeen adjusted to a frequency of 60 cycles per minute or 1 per second then it follows that, after six seconds have elapsed from the closing of the switch Sz, the armature A will Y drop and carry the contact |00 into engagement with the contact |0| whereupon an explosion will take place.

Another example of use of the system shown in Fig. 4 would be in connection with signalling where it is desirable to effect the operation of signals a fixed time interval after the closing of an electric circuit.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

l. A time relay system comprising a current source, a load to be connected with the source, means for connecting the load with the source and including a relay characterized by relatively high residual magnetism and having a pair of normally open contacts which when closed make an electrical connection between the source and load, an energizing coil on the relay for closing said contacts. a demagnetizing coil on the relay for removing the residual magnetism, means for momentarily connecting the relay energizing coil with the source, and means for connecting the demagnetizing coil with the source and including means set into operation in response to closing i of said relay contacts for intermittently making and breaking connection between the source and demagnetizing coil of the relay, so that the residual magnetism of the relay is reduced by a. plurality of successive impulses.

2. A time relay system comprising a. current source, a load to be connected with the source, means for connecting the load with the source and including a relay characterized by relatively high residual magnetism and having a pair of normally open contacts which when closed make an electrical connection between the source and load, an energizing coil on the relay for closing said contacts, a demagnetizing coil on the relay for removing the residual magnetism, means for momentarily connecting the relay energizing coil with the source, and means for connecting the demagnetizing coil with the source and including means set into operation in response to the closing vof said relay contacts for intermittently making and breaking conn tion between the source and the demagnetizing coil of the relay and between thejs'ource and the load, so that the residual magnetism of the relly is reduced by a series of impulses'coincilient with intermittent energization of the load.,

EQWARD M. CLAYTOR.

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