US2525334A

US2525334A - Time-delay relay

Info

Publication number: US2525334A
Application number: US650599A
Authority: US
Inventors: John S Baker
Original assignee: Cook Electric Co
Current assignee: Cook Electric Co
Priority date: 1946-02-27
Filing date: 1946-02-27
Publication date: 1950-10-10
Anticipated expiration: 1967-10-10

Description

Oct. 10, 1950 J. 5. BAKER 2,525,334

TIIIE DELAY RELAY Filed Feb. 27, 1946 &

IN V EN TOR.

71% J. M 3/426, W2 #21144, 4 711 Patented a. 10, 1950 TIME -DELAY RELAY John S. Baken-Chicaio, 111., minor to Cook Electric Company, Chicago, Ill., a corporation of Illinois A plication February 27, 1946, Serial No. 650,599

This application relates to time delay relays and more particularly to time delay relays wherein the time delay is produced by thermally responsive means.

Time delay relays usually include a relay embodying a coil, an armature adapted to be attracted by the coil, and contacts arranged to be operated by the armature along with some mechanism or apparatus eitherelectrical or mechanical to produce a delay in the functioning of the relay whether it is opening the contacts or closing them. Time delay relays operating upon purely electrical principles usually are provided with a short-circuited winding or slug in the relay magnetic circuit,'thereby providing a delay in the increase or decrease of the relay magnetic field, and hence, in the time of operation of the contacts whether opening or closing. Time delay relays operating upon mechanical principles include dash pot devices or escapement mechanisms to delay operation of the relay armature after energization or de-energi'zation has occurred. Such prior expedients have not been completely satisfactory. Only relatively short time delay intervals are obtainable or the additional time delay apparatus combined with the relay renders the relay bulky and subject to mechanical failures. It is an object of the invention to provide an improved time delay relay in which the time delay is produced by thermally responsive means.

It is a further object or the invention to provide an improved time delay relay that is not affected by ambient temperature variations.

It is a further object of the invention to provide an improved thermally responsive time tie- Claims. (Cl. 175-320) I ated by the armature.

lay relay: that is compact in form and simple in design.

In carrying out the invention in, one form, a time delay relay comprising a coil, contacts adapted to be operated thereby, and a thermally responsive element associated with the contacts for controlling the, operation ofthe coil after a time delay, is provided. In another form of the invention, a time delay relay is provided which comprises a coil, contacts adapted to be operated thereby, an energizing circuit for the coil including a normally open pair of the contacts, another energizing circuit for the coil including normally open thermally responsive contacts, along with an electric heater intimately associated with the thermally responsive contacts for controlling closure thereof to energize the coil through the other circuit after a time 'delay,

the heel I5 and lying alongside coil I2.

end of plate I8 opposite to heel I5, the armature thereby to close the normally open pair of contacts to complete the first energizing circuit.

For a more complete understanding of the in-' vention reference should now' be had to the accompanying drawing in which:

Figure 1 is a side elevational view of a relay embodying the invention;

F Fig. 2 is a top plan view of the relay shown in ig. l;

Fig. 3 is an end elevational view of the relay shown in Fig. l;

Fig. 4 is a circuit diagram embodying the relay of Fig. 1 in schematic form;

Fig. 5 is a circuit diagram of another form of the invention;

Fig. 6 is a circuit diagram of a still further form of theinvention; and

Fig. '7 is a circuit diagram of still another form of the invention.

Referring more particularly to the drawing, the invention is shown embodied in a relay I0, including a frame II, a coil I2, an armature I3, and a series of contacts I4 adapted to be oper- The frame II has an 'angularly bent portion or heel I5 to which the coil I2 including an iron core I6 is attached by means of a screw II. The frame II is also provided with a plate I8 extending at right angles to At. the

are provided respectively upwardly and inwardly directed tongues 23 and 24, which tongues rest uponthe top surface of plate I8 in the unenergized condition of coil I2.

Thecontact series I4 comprises two groups 3 springs 26 and 21 also have arc-resistant contacts at one end which are normally open. When the armature I3 is attracted by coil I2, the contacts of contact springs 28 and 23 are opened and the contacts of contact springs 26 and 21 are closed, since the tongue 24 bears against an insulating nipple 32' which is attached to contact spring 28, and the contact spring 21 is provided with an insulating nipple 33 which is engaged by the contact spring 28. Thus, when the armature is pivoted around shaft I3, the tongue 24 moves the contact oi. contact spring 28 away from the contact of contact spring 28 and correspondingly the contact of contact spring 21 is moved into contact with the contact of contact spring 26. The second group of contacts includes the

contact springs

32, 33, 34, 35 and 36 separated from each other by means of insulators 31. The

contact springs

32, 33, 35 and 36 are provided with arc-resistant contacts at one end and referring to Figs. 1 and 3, it will be seen that the contact spring 34 includes a pair of contacts at its forward end, one of which is in normally closed relationship with the contact of contact spring 35, and the other of which is in normally open relationship with the contact of contact spring 36. Thus when the armature I3 is actuated, the tongue 23, acting through an insulating nipple 20 attached to contact spring 36, moves the contact spring 36 into contact with one of the contacts of contact spring 34 to form a closed circuit, and at the same time it forces contact spring 34 away from contact spring 35 to form an open circuit between the contacts of these two contact springs.

The

contact springs

32 and 33 are thermally responsive elements such for example as bimetallic strips and are so disposed with respect to each other that if the two strips are heated equally they will be distorted or' bent in the same direction and thereby always maintain their contacts in the same position, this position being normally open in Fig. 1. Thus changes in ambient temperature, for example, will not change the relative position of

thermal elements

32 and 33. The thermal element 33 is provided with an electric heater 38 which for example may be an electric resistance wire wrapped around this element and insulated from the surroundings by any suitable means, such for example as a coating of shellac or varnish. Referring to Fig. 4 and to Fig. l, the end of thermally responsive strip 32, opposite to the contact end, is connected by means of a conductor 33 to one terminal of coil I2 and by means of conductor 59 to the corresponding end of the contact spring 36. Contact spring 34 issimilarly connected by means of conductors 4i and 58 to the corresponding end of thermally responsive strip 33. One end of electric heater 38 is connected to contact spring 35, and the other end of the heater is connected through a conductor 42 and a variable contact 43 to a resistor 44 and thence through a conductor 45 to one terminal of coil i2.

For an explanation of the operation of the invention reference is directed to Fig. 4. A source of voltage, which for example may be a battery 41, is provided along with a switch 48, both connected in circuit with the relay for obtaining relay operation. While the battery 41, a direct current source, has been shown, it will be understood that other sources of power such for example as alternating current may be used. The circuit shown in Fig. 4 embodies the relay as shown in Fig. 1 and is an arrangement whereacres.

4 by relay coil I2 is energized to operate the relay contacts a certain time interval after switch 43 is closed. Thus the various elements are shownin their normally inoperative positions. On closing switch 48 a circuit is completed through heater 33 as follows: From battery 41 through

conductors

43 and 43, a portion of resistor 44. variable contact 43, conductor 42, heater 38, conductor 53, contact spring 35, contact spring 34, conductor 4I, conductor 55 through switch 48. and conductor 56 to the battery 41. Accordingly, the heater 33 begins to heat the thermally responsive element 33, which, after the incident time delay interval, is distorted to close contact with thermally responsive element 32. At this occurrence a circuit is completed for energizing coll I2 as follows: From battery 41 through conductor 43, through coil I2, conductor 33, thermal element 32, thermal element 33, conductor 58, conductor 55, switch 43, and conductor 56 to the battery 41. Accordingly, the coil I2 is energized, attracts the armature I3, and closes the circuit between the contacts of

contact springs

34 and 36 and opening at the same time the circuit between the contacts of

contact springs

34 and 35. Closing the circuit including the contacts of

contact springs

34 and 36 completes a second circuitfor energizing coil l2 as follows: From battery 41 through conductor 43, coil I2, conductor 53,

contact springs

36 and 34, conductors 4i and 55, switch 48, conductor 56 to battery 41. Opening 'the circuit between the contacts of

contact springs

34 and 35 interrupts the circuit to heater 38 which accordingly allows thermally responsive element 33 to cool, and hence, opens the contacts between

thermal elements

32 and 33. Opening the circuit between these latter two elements interrupts the first energizing circuit for coil I2 and the circuit is in position for repeat operation whenever theswitch 48 is opened. Of course when armature I3 is attracted, the circuits operated by contact springs 28 and 23 are opened and the circuits operated by contact springs 26 and 21 are closed and vice versa when the armature is released.

After switch 48 is closed, coil I2 is energized when thermally

responsive elements

32 and 33 close the circuit between them and these latter elements close the circuit whenever sufl'icient heat is produced by heater 33 to distort the element 33 suiiiciently to close the contacts. Thus the time of energizing coil I2 is controlled by the thermally

responsive elements

32 and 33 and the associated heater 38. Since resistor 44 may have varying portions thereof connected in circuit with heater 38 by the variable contact 43, the amount of current received by heater 38 may of course be controlled, and hence the time elapsed before thermally responsive element 33 closes its contacts with the corresponding element 32 may be controlled.

Fig. 5 illustrates schematically an embodiment of the invention in which the coil I2 of the relay is de-energized after an elapsed time interval from the closing of switch 48. The coil I2 and the contact springs 26, 21, Y28 and 23 correspond to the elements similarly numbered in Fig. 4. Associated with contact springs 26-23 in a manner similar to that illustrated in connection with Figs. 1 and 4 are the contact springs 6| and 62, and thermally responsive elements 63 and '64, a resistance heater 65 being intimately associated with thermally responsive element 64 and connected thereto at one end as shown. In the inoperative position of this circuit, the thermally

ruponsive elements

66 and 64 are in the closed position, and, when the heater 65 is energized, the thermally responsive element 64 after the incident time delay opens the contacts between these elements. The contact springs 6| and 62 including arc-resistant contacts form a normally open circuit.

When switch 46 is closed, an energizing circuit for coil I2 is completed as follows: From the battery 41 through conductor 66, through switch 46, conductor 61, coil |2 to battery 41. Coil |2 immediately attracts armature l3, closes the contacts 01 contact springs 6| and 62 as well as the contacts of contact springs 26 and 21, and opens the circuit between the contacts of contact springs 26 and 26. When contact springs 6| and 62 close the circuit between them, substantially no current is supplied therethrough to the thermally

responsive elements

63 and 64 and the re-v lated elements since switch 48 effectively provides a short circuit. However, when the switch 46 is opened (the time delay of contact operation occurs in this circuit after the switch is opened), a circuit is completed through the heater 65 as follows: From battery 41 through conductor 66, conductor 16, conductor 66, heater 65, thermally

responsive elements

64 and 63, closed contacts of contact springs 62 and 6|, conductor 61, coil |2, and battery 41. Accordingly the heater 65 begins to heat up and after the incident time interval the thermal element 64 opens its contacts with thermal element 63, thereby de-energizing coil 2 which allows the armature to drop out and the various contacts to assume their normally inoperative positions. In this circuit, the heater for supplying heat to the thermally responsive elements is unenergized when the switch 46 is closed and becomes energized only when the switch 48 is opened. Thereafter, the coil I2 is de-energized when the thermally responsive elements open their contacts.

' In order to vary the time interval elapsing between opening of switch 46 and opening of

contacts

63 and 64, the variable resistor 66 is connected to the thermally responsive element 64 and to the heater 65 and through the variable contact 1| to the Junction of the conductors 16 and 66. Thus the heater 65 is in one branch of a parallel circuit and a portion of the resistor 66 is in the other branch, the parallel circuit being in series with coil |2. Varying the value of the resistor 66 then varies the amount of current flowing through the heater 65 as is well understood and hence, varies the time delay before de-energization of coil l2.

Fig. 6 illustrates an arrangement similar to Fig. 5 for producing a time delay between the opening of switch 46 and the de-energization of coil I2. In this arrangement, the resistor 66 for varying the time delay of heater 65 is connected directly in parallel with coil 2 rather than in one branch of a parallel circuit of which the heater 65 is in the other branch. In Fig. 6, when switch 48 is closed, current is supplied to coil l2 through a circuit including battery 41, conv and conductors 14 and 15 to 41, conductor 16, conductor 66, heater 66,

thermal elements

64 and 63, closed contacts 01' contact springs 62 and 6|, conductors 12 and 16, coil |2, battery 41. Thus the heater 65 supplies heat to element 64 which opens its contact with element 66 after the incident time delay to de-energize coil |2. Placing the resistance 66 in parallel to coil |2 places a parallel circuit combination including resistor 66 and coil 2 in series with heater 65 whenever switch 46 is opened. Hence by varying the value of resistor 66, the value of the parallel resistance combination oi resistor 66 and coil I2 is varied, and hence the total current taken by heater 65 is varied. This varies the heating value of heater 65, and hence the time delay pro- ;igced by thermally responsive elements 64 and The circuit of Fig. 7 combines the circuits of Fig. 4 and Fig. 5. Thus the conductors and 56 of Fig. 4 and the conductor 16 and the contact spring 6| of Fig. 5 are connected across the switch-46. In the normally inoperative position of the circuit (switch 48 is open), the contacts of contact springs 6| and 62 are open, the contacts of contact springs 34 and 35 are closed, and the contacts of contact springs 34 and 36 are open. When switch 46 is closed a circuit is completed through heater 38, through the circuit previously described in connection with Fig. 4, and since the contacts of contact springs 6| and 62 are open no energy is supplied to heater 65. After thermal element 33 is heated sufliciently by heater .36, the

thermalelements

33 and 32 close to energize coil |2, also through a circuit previously described, the coil becoming energized and closing contacts of contact springs 34 and 36 while at the same time opening the contacts of contact springs 34 and 35. Opening the circuit of contact springs 34 and 35 de-energizes heater 36. permitting it to cool for a repeat operation. When coil |2 picks up the contact springs 26 and 21 are closed and the contact springs 21 and 26 are opened. Thus the circuit described produces a delay in the energization of coil |2 after closing of switch 48, the amount of the delay being determined by the setting of variable contact 43 on resistor 44.

ductor 10, switch 48, conductor 12, conductor 13, coil |2, conductor 14, and conductor 15 to battery 41. This circuit also supplies current to the resistor 66 which has one side connected to the junction of conductors 14 and 15 and has .its other side connected through the variable contact 1| to the junction of conductors 12 and 13. Energizing coil |2 closes contacts 6| and 62 so that when the switch 48 is opened a circuit for coil I2 is completed extending from battery In the further operation of the circuit of Fig. 7, when coil I2 is energized contact springs 6| and 62 are also closed. However, since; switch 46 'forms a short'circuit around conductor 16 and contact spring 6|, the heater 65 receives substantially no current during this phase of the operation. Subsequently, after switch 46 is opened, a circuit for coil I2 is established as 'follows: From battery 41 through conductor 46,

coil |2, conductor 56, closed contact springs 36 and 34, conductor 55, conductor 16, conductor 68, heater 65,

thermal elements

64 and 63, closed contact springs 62 and 6|, and conductor 56 to battery 41. Accordingly the coil |2 remains energized while at the same time the heater 65 is receiving current and is becoming heated. After the incident time delay interval, the thermally responsive element 64 is distorted sufliciently to asses tions to delay the operation of contact springs 26-29 until the time delay occasioned by the thermally responsive elements 32 and 13, along with the associated heater 38, permit energizetion of coil l2, and after cbil I2 is energized it remains so until switch 48 is opened. After switch 48 is opened the left hand portion of the circuit shown in Fig. '7 maintains the coil l2 energized, thereby maintaining contacts 26-49 in their operative condition until the delay occasioned by the thermallv responsive elements 64 and i3 and the associated heater 65 permit de-energization of coil i2 and the consequent movement of contacts ZS-29 to their inoperative positions. The resistor 44 associated with the right hand portion of circuit of Fig. 7, and the resistor lil associated with the left hand portion thereof, may be adjusted to give the desired time delay interval occasioned by the respective thermally responsive elements.

Without further elaboration, the foregoing will so fully explain the gist of my invention that others may, by applying current knowledge, readily adapt the same for use under varying conditions of service, without eliminating certain features, which may properly be said to constitute the essential items of novelty involved, which items are intended to be defined and secured to me by the following claims.

I claim:

1. A time delay relay comprising a coil, contacts adapted to be operated thereby, closed thermally responsive contacts associated with said contacts, an electric heater intimately associated with said thermally responsive contacts for controlling the opening thereof after a time delay, one circuit for energizing said coil, and a circuit in parallel to said one circuit including a normally open pair of said contacts, said thermally responsive contacts and said electric heater, the energizing of said coil through said one circuit closing said pair of contacts thereby energizing said coil and said electric heater through said parallel circuit when said one circuit is opened and thereafter opening said thermally responsive switch to de-energize said coil after a time delay.

2. A time delay relay comprising a coil, contacts adapted to be operated thereby, thermally responsive contacts associated with said contacts, an electric heater intimately associated with said thermally responsive contacts for controlling the opening thereof after a time delay, time delay varying means associated with said'electric heater, one circuit for energizing said coil, and a a normally open pair of said'contacts, said thermally responsive contacts. and said electric heater, the energizing of said coil through said one circuit closing said pair of contacts thereby energizing said coil and saidelectric heater through said parallel circuit when said one circuit is opened and thereafter open-ingsaid thermally responsive switch to de-energize said coil after a time delay.

3. A time delay relay comprising a coil, contacts adapted to be operated thereby, thermally responsive contacts associated with said contacts, an electric heater intmately associated with said thermally responsive contacts for controlling the opening thereof after a time delay, a resistor associated with said electric heater for varying the time delay of said thermally responsive means,

,one circuit for energizing said coil, and a circuit in parallel to said one circuit including a normally open pair of said contacts, said thermally responsive contacts and said electric heater, the energizing of said coil through said one circuit closing said pair of contacts thereby energizing said coil and said-electric heater through said parallel circuit when said one circuit is opened and thereafter opening said thermally responsive switch to de-energize said coil after a time delay.

4. A time delay relay comprising a. coil, contacts adapted to be operated thereby, one energizing circuit for said coil including a normally open pair of said contacts, a second energizing circuit for said coil including normally open thermally responsive contacts, a first electric heater intimately associated with said thermally responsive contacts for controlling the closing thereof after a time delay, a circuit for energizing said first electric heater including a normally closed pair of said contacts, normally closed thermally responsive contacts, a second electric heater intimately associated with said normally closed thermally responsive contacts, a third circuit for energizing said coil including said normally closed thermally responsive contacts, said second heater and a normally open pair of said contacts, and a switch associated with said circuits, whereby first closing said switch energizes said first heater through the energizing circuit for said first heater to effect energization of said coil after a time delay, thereby closing said pairs of normally open contacts and energizing said coil through said one circuit and opening said normally closed pair of contacts to de-energize said first heater and thereafter opening said switch energizes said coil through said third circuit thereby to open said normally closed thermally responsive contacts after a time dela to 1 de-energize said coil.

5. A time delay relay comprising a coil mounted on a frame, a contact pile mounted on said frame, an armature pivotally mounted on said frame for actuation by said coil, said armature including arms engaging the contacts of said pile for operation of said contacts when said armature is actuated by said coil, closed thermally responsive contact members associated with said contact pile, an electric heater intimately associated with said thermally responsive contact members for controlling the opening thereof after a time delay, one circuit for energizing said coil, and a circuit in parallel to said one circuit including a normally open pair of contacts, said thermall res nsive contact membe circuit in parallel to said one circuit including y m rs and Sam electric heater, the energization of said coll through said one circuit closing said pair of contacts thereby energizing said coil and said electric heater through said parallel circuit when said one circuit is opened and thereafter opening said thermally responsive switch to de-energize said coil after a time delay.

JOHN s. BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

v UNITED STATES PATENTS Number Name 7 Date 1,746,827 Fry Feb. 11, 1930 1,9a3,5oe Willing Dec. 4, 1934 2,057,384 Lamb Oct. 1a, 1930 2,194,634

Betz Mar. 26, 1940