US3390361A - Variable time delay reed relay having a movable core - Google Patents

Description

June 25, 1968 c. A. BODGE 3,390,361

VARIABLE TIME DELAY REED RELAY HAVING A MOVABLE CORE Filed Aug. 17. 1966 5 Sheets-Sheet 1 F l G1.

35 H7 37 Iv //////y////////// 7r: I I :5 36 29 v June 25. 1968 c. A. BODGE 3,390,331

VARIABLE TIME DELAY REED RELAY HAVING A MOVABLE CORE Filed Aug. 17. 1966 3 Sheets-Sheet 2 Jun 25, 1968 .'A. BODGE 3,390,361

VARIABLE TIME DELAY REED RELAY HAVING A MOVABLE CORE Filed Aug. 17. 1966 5 Sheets-Sheet 3 \\1 74\ y -91 W P 75 I a? 4 1 i I 79 3 I ll \V "vs? 8 85 W 7 s' United States Patent 3,390,361 VARIABLE TIME DELAY REED RELAY HAVING A MOVABLE CORE Clifford A. Bodge, Attleboro, Mass., assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed Aug. 17, 1966, Ser. No. 572,947 12 Claims. (Cl. 335-152) This invention relates to improved electric 'elay switches.

Among the several objects of the invention may be noted the provision of a sensitive and low-cost electric relay switch which may be constructed for time-delay action, or without it; the provision of a switch of the class described in which the time delay may be made variable; the provision of a switch of the class described which, although employing sensitive electrically sealed switch contacts for reliable operation in unsafe atmospheres, may be constructed to operate in response to heavy load currents to be sensed; the provision of a switch of this class which may be compactly constructed for gang operation; and the provision of such a switch which may be operated in any position without excessive variation in calibration. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which several of various possible embodiments of the invention are diagrammatically illustrated.

FIG. 1 is an axial section through a switch made according to one form of the invention;

FIG. 2 is an axial section of a switch made according to a second form of the invention;

FIG. 3 is an axial section illustrating a third form of the invention;

FIG. 4 is a right-hand end view on a reduced scale of FIG. 3;

FIG. 5 is an axial section showing a fourth form of the invention; and

FIG. 6 is a diagram of a reed switch having normally closed contacts.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

There is known in the switching art a so-called reed switch which comprises a pair of cantilevermounted springy blades of magnetizable material in ribbon or like form. The blades are hermetically sealed in containers of glass or other substantially nonma-gnetizable material. The ends of the blades overlap but are normally sprung open or separated in their containers. In the case of a normally open switch, both blades may carry current. In the case of a normally closed reed switch the blades operate an auxiliary normally closed switch in the container. Upon sufficient magnetization the overlapped ends become oppositely polarized and attract one another to close a normally open switch or to open a normally closed switch. The glass containers have air excluded therefrom and to that end may be evacuated or infilled with a protective atmosphere such as hydrogen or nitrogen. The blades of such switches have little inertia so that they operate very sensitively over a time interval on the order of a millisecond or so, unless time-delay means are provided. These switches involve no wearing sliding parts, bearings or the like. In the following description the invention is described in connection with single-pole, single throw, reed switches which have normally open current-carrying con- 3,390,361 Patented June 25, 1968 tact-s. However, as will be clear to those skilled in the art, it has utility by use also of reed switches having auxiliary normally closed circuit-carrying contacts, and being of the single-pole, double-throw variety. The latter are shown diagrammatically in FIG. 6, to be described below.

Referring now more particularly to FIG. 1 of the drawings, there is shown at numeral 1 a reed switch such as above referred to comprising two springy ribbons 3 of magnetizable material such as a ferrous material. In the present example, the blades are located in glass container 5 with their inner ends overlapping but normally spaced from one another in switch-open positions, as indicated at 7. The outer ends of the blades extend through the ends to the container, in which they are hermetically sealed, so as to form terminals 9. As above stated, the container may be evacuated or filled with protective atmosphere such as hydrogen or nitrogen.

In the FIG. 1 form of the invention the reed switch 1 is located on the central axis of a cup-shaped cylindrical steel container'll. The bottom 13 of the container 11 may be electrically connected to one blade terminal 9, as shown by the solder connection 15. Locate-d within one end of the container 11 is an insulating spool 17, composed of nylon or the like, around which is wound an annular field coil 19. In the other end of he container 5 and surrounding a portion of it is a bobbin of insulation 21. Between the spool 17 and the bobbin 21 is a magnetizable (steel, for example) washer 23. Insulated conductive leads 25 extend from the coil 19 through the spool 17, washer 23 and insulation 21. At numeral 27 is a header which is soldered to the container 11. The header contains glass seals 29 and 31. The conductors 25 extend through the seals 29, and one terminal 9 of switch 1 extends through the other seal 31.

Surrounding the cylindrical reed switch 1 is a magnetizable (steel) sleeve 33. The sleeve 33 is slidable within the spool 17, washer 23 and a recess 37 in the bobbin 21. One end of recess 37 forms a stop for movement of the sleeve 33. The sleeve 33 has a loose fit around the container 5 and within the spool 17, washer 23 and recess 37. It is biased by a spring 35 to the limiting stop position in the recess, as shown in FIG. 1. The sleeve 33 is movable against the bias of return spring 35 located in the space between the glass container 5 and the spool 17. This space is filled with a damping fluid which may be silicone oil, for example. The sleeve 33 in its spring-biased position such as shown in FIG. 1 surrounds the overlapped ends of the reeds 3. This is its position when the coil 19 is deexcited.

Upon excitation of the coil 19, a toroidal flux field will be initiated and build up around the coil. This will in part extend through the magnetic gap 36 around the extended spring 35. This gap 36 has a substantial reluctance. At this stage very little flux reaches the lapped portion of blades 3, because the whole length of the sleeve surrounds the lap 7. Hence for a time the reed switch 1 remains open. When the coil 19 is fully excited the sleeve 33 will be magnetically attracted to the left from its righthand position around the overlap 7. As the gap 36 becomes smaller, the reluctance in the magnetic circuit decreases. As a result, the increased magnetic pull upon the sleeve 33 increases against reaction from the spring 35. The oil gradually escapes from the left end of the sleeve 33 to its right end through the loose fit of the sleeve 33 in its containing space. This effects a considerable time delay in complete movement to the left, of sleeve 33 after initial excitation of the coil 19. Upon complete movement of the sleeve 33 to the left, the reluctance in the flux path is small. Thus the flux field is strong. Moreover, the lap 7 between blades 3 is no longer surrounded by sleeve 33 and becomes exposed to leakage flux forming part of the flux circuit. This flux oppositely polarizes the portions of blades 3 at lap 7, whereupon they attract one another. This closes the switch 1, with time delay. Upon deexcitation of coil 19 the switch 1 opens immediately.

Referring now more particularly to FIG. 2, there is shown a second form of the invention. In this case the operating parts are encased in a suitable insulating housing illustrated by the dotted lines 39. The parts contained within and supported by the housing comprise line terminals 41 having conductive leads 43 which extend to an annular field coil 45 wounnd on an insulating spool 47. The spool 47 is carried upon a nonmagnetic (copper, for example) container 49 having an enclosing cap 51. In the container is an infilling in gap 52 of hydraulic damping fluid. Two loosely fitting magnetizable cores 53 in container 49 are biased apart by a spring 55. The container 49 is mounted between two ferrous supports 57. Carried on the supports 57 and outside of the field coils 45 is a reed switch 59 similar to the one described in connection with the description of FIG. 1. Its blades 61 are connected to quick-connect conductive terminals 63- for connection to a circuit to be cont-rolled.

The path of the toroidal fiux field established by coil 45 when excited includes blades 61, supports 57, the cores 53 and the initially large gap between the core 53. Upon excitation, the cores 53 are drawn together against the compression of spring 55 and with time delay, due to the action of the fluid as it transfers from between the cores 53 to their outsides through the loose fit that they have in the container 49. As the gap and its reluctance decrease, the magnetization of the blades 61 increases until the lapped ends of the blades become sufliciently polarized to attract one another into contact, thus closing the switch 59. The advantage of having a pair of core plungers such as 53 is that the device as a whole may be mounted in any one of various angular positions in gravity or accelerating force fields and have less variation in the time-delay action than when a single core plunger is used, as in FIG. 1, or in FIG. to be described. Upon deexcitation of coil 45 the switch 59 opens immediately.

In FIGS. 3 and 4 is shown another form of the invention for gang operation, in which numeral 65 indicates an annular field coil wound around an insulating spool 67. Spool 67 surrounds and is carried upon a time-delay assembly 68 like that shown in FIG. 2 and in which like numerals designate like parts. Supported between the flanges of the spool 67 and outside of the coil 65 are plurality of reed switches 69 of the same type as reed switches 1 and 59, above described, having end-lapped blades 70. Threaded through one flange of the spool 67 adjacent each reed switch 69 is a magnetizable calibrating screw 71 (see FIG. 4). Numeral 72 indicates magnetizable supports. Each screw forms a variable magnetic shunt for the blades of its adjacent reed switch. Thus this form of the invention illustrates the possibility of gang operation of several reed switches and means for individually calibrating the reed switches for different closing times or coil current levels.

In FIG. 5 is shown another form of the invention in which an annular field coil 73 wound on an insulating spool 74 is positioned around a time-delay assembly 75 and carried in a magnetizable cup 77. The timedelay assembly 75 is constituted by a container 79, capped as shown at 81 and within which is a single movable magnetizable core 83 biased toward the left end of the container 79 by a compression spring 85. The core 83 has a loose fit in the container and the container is filled with a damping fluid. Mounted crosswise within a groove in the magnetizable cap 81 is a reed switch 87 such as above described. Epoxy resin may be used for attachment. When excitation of the coil 73 is initiated there is at first a high-reluctance gap 80 in the time-delay assembly 75 which weakens the part of the field which passes through cap 81. In this event the leakage flux reaching the blades 82 of switch 87 is small. As the core 83 with time delay is drawn to the right, the gap and its reluctance decrease, thus increasing the strength of the magnetic field at lap 92. This subjects the blades 19 to increased leakage flux, thereby closing them at their overlap 92. FIG. 5 illustrates that the position of a reed switch or switches need not be parallel to the axis of the annular exciting coil.

It will be understood that the variable calibrating features, such as by the screws 71 (FIGS. 3 and 4) or their equivalent, may be employed with the reed switches of the other forms of the invention shown in FIGS. 1-4.

It will also be understood that a field coil such as 25, 41, 65 or 73 may be made current-sensitive by using a small number of winding turns and connecting the coil in series with a circuit to be sensed; or voltage-sensitive by using a large number of winding turns and connecting the coil in parallel in a circuit to be sensed. In the former case large currents can be sensed, as for example 100 amperes in the coil, without damage to the contacts of the sensitive reed switch or switches.

In all forms of the invention the time-delay feature may be practically eliminated by removing any damping fluid from the space containing the slidable cores such as 33, 53 or 83 and providing suitable openings from such space to the atmosphere, as will be obvious to those skilled in the art.

It will be seen that the sensitive reed switches function by increasing polarization at the lapped portions of their blades until such portions attract one another to operate the switch. FIG. 6 illustrates diagrammatically a single-pole, double-throw reed switch which may be substituted for the single-pole, single-throw reed switches above described.

Referring to FIG. 6, numeral 93 indicates the glass or like container in which magnetizable blades 95 and 97 are hermetically sealed. An auxiliary contact 99 is hermetically sealed into the container 93 and is normally engaged by blade 95 to close a circuit across leads 101 which is to be controlled. When the magnetizable blades 95 and 97 are magnetized they are drawn into contact and the endof blade 95 is withdrawn from the contact 99, thus opening the circuit through leads 101. If desired, an additional circuit to be controlled may be connected to the blades 95 and 97.

In the illustrated forms of the invention the circuits to be sensed are connected to the magnetizing field coils and the circuit or circuits to be controlled are connected to the reed switches. It will be understood that the field coils can be interconnected with the reed switches to perform other functions.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A relay comprising a sealed reed switch having magnetizable contact-operating blades, an electric coil for establishing when excited a magnetic field throughout a certain path, said path including a magnetizable part and said blades, a movably mounted core piece positioned in said path and movable to and from said magnetizable part, resilient means biasing said core-piece to establish a comparatively large space with respect to said part in said path when the coil is deexcited, said core piece being magnetically drawn toward said part against the bias of said biasing means to reduce said space upon substantial excitation of the coil, whereby said magnetic field is strongly enough established throughout said path to magnetize said blades for operation thereof.

2. A relay comprising an assembly of cantilever-mounted magnetizable spring blades in a hermetically sealed container, terminals outside of said container and conductively connected with said blades through insulating hermetic seals;

said blades including in the container contactable portions, said portions having normal first circuit-controlling positions relative to one another, an electric coil for establishing a magnetic field, a movable mounted magnetizable core piece positioned in said magnetic field when the latter is established,

means biasing said core piece to establish a magnetic gap of comparatively high reluctance in the field when the coil is deexcited, said core piece being magnetically attached against bias from said biasing means to reduce said gap upon substantial excitation of the coil, whereby said reluctance is decreased and said magnetic field is increased,

said assembly being mounted relative to the coil in a position wherein change of polarization of said magnetizable spring blades will be effected by said field when the field is substantially increased and said blades in response to said change in polarization will assume a second circuit-controlling position relative to one another.

3. A relay switch comprising an annular field coil wound about an axis and forming a toroidal flux field when the coil is excited, a container in the coil extending along its axis, damping means in the container, a core movable in the container and subject to said damping means to close a high reluctance gap in the flux field, said core being moved by the flux field coil when excited to decrease said gap and reluctance, a reed switch of cylindrical form containing switch blades extending substantially along its axis, said reed switch being positioned in said flux field when the coil is excited, the axis of the reed switch and that of the coil being substantially parallel.

4. A relay switch according to claim 3, wherein the axis of the reed switch lies within the annular coil.

5. A relay switch according to claim 3, wherein the axis of the reed switch is located outside the periphery of the coil.

'6. A relay comprising an electric coil wound annularly around an axis, an elongate reed switch extending into the coil along said axis and having lapped magnetizable switching blades extending substantially parallel to said axis, means at one end of the switch and within the coil-forming space to provide substantial magnetic reluctance and containing damping means, spring means in said space, a magnetizable sleeve around the reed switch, said sleeve when the coil is deexcited being biased by said spring means into position surrounding said lapped portions of the blades to shunt magnetism therefrom and being magnetically drawn into said space against the action of said spring and the damping means when the coil is excited to decrease said space and reluctance while exposing the lapped portions of said blades to the increasing magnetic flux generated by the coil, whereby the blades are activated to eifect switching.

7. A relay comprising an electric coil formed annularly around an axis to produce a toroidal magnetic field, means forming space of relatively high reluctance in the field within the coil and containing damping means, a magnetizable core means movable in said space to reduce the reluctance when the coil is excited, and an elongate magnetizable reed switch positioned relative to the coil for magnetic operation by the field from said coil when the reluctance is reduced.

8. A relay according to claim 7, wherein the length of the reed switch is at a substantial angle to the axis of the coil.

9. A relay according to claim 8, wherein said angle is approximately 10. A relay according to claim 7, including adjustable magnetizable means associated with the reed switch for adjustably shunting a part of the toroidal field from its blades.

11. A relay switch comprising an annular field coil wound about an axis and forming a toroidal flux field when the coil is excited, a cylindrical container in the coil extending along its axis, a high-reluctance gap and damping means in the container, at least one core in the container movable to reduce said gap and reluctance when the coil is excited, a plurality of reed switches of generally elongated forms containing magnetizable switch blades extending substantially along the lengths of the reed switches, said reed switches being located in a series around said field coil.

12. A relay switch according to claim 11, including adjustable magnetizable means associated with each reed switch for adjustably shunting a part of the toroidal field from it.

References Cited UNITED STATES PATENTS 3,184,563 5/1965 Myatt 335-153 BERNARD A. GILHEANY, Primary Examiner.

R. N. ENVALL, JR., Assistant Examiner.

Claims (1)

1. A RELAY COMPRISING A SEALED REED SWITCH HAVING MAGNETIZABLE CONTACT-OPERATING BLADES, AN ELECTRIC COIL FOR ESTABLISHING WHEN EXCITED A MAGNETIC FIELD THROUGHOUT A CERTAIN PATH, SAID PATH INCLUDING A MAGNETIZABLE PART AND SAID BLADES, A MOVABLY MOUNTED CORE PIECE POSITIONED IN SAID PATH AND MOVABLE TO AND FROM SAID MAGNETIZABLE PART, RESILIENT MEANS BIASING SAID CORE PIECE TO ESTABLISH A COMPARATIVELY LARGE SPACE WITH RESPECT TO SAID PART IN SAID PATH WHEN THE COIL IS DEEXCITED, SAID CORE PIECE BEING MAGNETICALLY DRAWN TOWARD SAID PART AGAINST THE BIAS OF SAID BIASING MEANS TO REDUCE SAID SPACE UPON SUBSTANTIAL EXCITATION OF THE COIL, WHEREBY SAID MAGNETIC FIELD IS STRONGLY ENOUGH ESTABLISHED THROUGHOUT SAID PATH TO MAGNETIZE SAID BLADES FOR OPERATION THEREOF.

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