US3470504A

US3470504A - Polarized electrical relay

Info

Publication number: US3470504A
Application number: US668050A
Authority: US
Inventors: Henry Rogers Mallory; Alexander C Wall
Original assignee: ALEXANDER C WALL
Current assignee: ALEXANDER C WALL
Priority date: 1967-09-15
Filing date: 1967-09-15
Publication date: 1969-09-30
Anticipated expiration: 1986-09-30

Description

Sept. 30, 1969 POLARI ZED ELECTRICAL RELAY Filed Sept. 15, 1967 2 Sheets-Sheet 1 36 I 24 4 38 33 32 26 um I N /174 3 7 39 3 I9 2| 35 34 I7 le 2s 30 .33 29 40 l5 l6 I 4 Illll l6 |3 3| IS m I Q 4| 333 29 4O v 44 2| V v v v 37 2s-\ 1 IIIIIIIIHH S 36 l6 I M l4 i 30 M Y 40 '5 l I INVENTORS HENRY R. MALLORY ALEXANDER C. WALL ATTORNEY Sept. 30, 1969 H. R. MALLQRY ET POLARIZED ELECTRICAL RELAY Filed Sept. 15. 1967 2 Sheets-Shae L .2

IIIIII Fla-a INVENTORS HENRY R. MALLORY ALEXANDER c. WALL BY I v ATTORNEY 1 United States Patent 3,470,504 POLARIZED ELECTRICAL RELAY Henry Rogers Mallory, Winding Lane, Greenwich, Conn. 06830, and Alexander C. Wall, Beach Drive, Darien, Conn. 06820 Filed Sept. 15, 1967, Ser. No. 668,050 Int. Cl. H01h 51/22 US. Cl. 335-78 3 Claims ABSTRACT OF THE DISCLOSURE A dipole magnet moves longitudinally under the influence of a surrounding solenoid electromagnetic coil. The magnet is latched in position at either end of its travel by a magnetic element after deenergization of the coil. The magnet is mechanically coupled to a set of movable contacts for control of a load circuit. Further control over the motion of the magnet may be obtained by the use of compressible bumpers or pneumatic pressure. The magnet may be self-induced or exteriorly induced.

The present invention concerns a novel polarized relay, and more particularly one well suited to the control of primary branch electrical circuits for lighting and power purposes in houses, business establishments and industry. Several types of such circuits utilize a momentary control switch which allows half-cycles of one polarity to pass when the switch is turned on and which passes halfcycles of an opposite polarity when the switch is turned off; when the momentary switch is released from either position, no control current may pass therethrough. Therefore, a control relay for such a system must be polarity-sensitive and must latch in either the open or closed position, so that the power-controlling contacts remain in the open or closed position after the remotely operated momentary switch has been released. Relays used in conventional low-voltage control systems have been equipped with an over-center spring member for latching, a complicated ratchet or sequencing device, or a complex and somewhat inefiiicient magnet and spring assembly. Furthermore, many of the conventional relays for these applications incorporate either two separate coils or a double-winding coil to provide the necessary polarity discrimination. The present relay has a single coil with only two terminals.

The present invention provides a simple and economical relay having a small number of easily manufactured parts. In addition, the high-voltage contacts are well insulated from the low-voltage portion of the relay. Furthermore, the present relay is inherently rugged and is subject to significantly less wear in operation than are conventional relays. Briefly, the present relay accomplishes these and other objects by incorporating a housing, a single-coil solenoidal electromagnetic coil and an elongated magnet having a pole at each end and longitudinally movable within the coil. A latching element made of a magnetizable material is then located adjacent each end of the magnet at its limits of longitudinal travel for retaining the magnet at one or the other of these positions. The magnet is mechanically coupled to a movable contact arm for engagement with a fixed contact arm attached to the housing.

Other objects and advantages of the present relay, as well as modifications obvious to those skilled in the applicable arts and Within the scope of the appended claims, will become apparent from the following description of several preferred embodiments thereof, taken in conjunction with the accompanying drawing, in which:

ice

FIGURE 1 is a side view in cross section of a first form of relay according to the invention;

FIGURE 2 is a side view in cross section of a second form of relay;

FIGURE 3 is a cross-sectional view of a third form of relay;

FIGURE 4 shows a cross section of a fourth form of relay; and

FIGURE 5 illustrates, partly in elevation and partly in schematic, a relay according to the invention with its associated load and control circuits.

Referring more particularly to the drawing, FIGURE 1 shows a relay with a housing 10 having a low-voltage or control portion 11, preferably made of a material which is both magnetic and electrically conductive, and a highvoltage or load portion 12, preferably of an insulating material such as plastic. Situated within the control portion 11 of the housing 10 is a solenoid electromagnetic coil 13 wound on a bobbin 14. The coil 13 has a pair of cointrol leads 15 extending through apertures 16 in the rear wall 17 of the control portion 11. Along the axis of the coil 13 lies a magnet 18 which moves longitudinally within the cylindrical passage 19 of the bobbin 14. The magnet 18 forms the armature of the relay. Since this magnet is positioned asymmetrically along the axis of the coil 13, the coil exerts more force upon the end pole 20 than it does upon the opposite end pole 21. Therefore, energization of the coil by current flowing therethrough with one polarity will urge the magnet 18 toward the rear wall 17, while current of opposite polarity will constrain the magnet 18 to move in the opposite direction, by the dipole magnetic field set up when current flows in a solenoidal coil. Fabricating the control portion 11 of the housing 10 of a magnetic material such as steel enhances the effectiveness of the coil 13 by concentrating its field within the enclosure; it also shields the magnet 18 from the influence of stray magnetic fields outside the relay, such as may be caused by nearby power wiring.

In the applications primarily contemplated for the relay, the coil 13 will be energized momentarily to move the magnet 18 selectively to one end or the other of its travel; thereafter it is desired that the magnet be latched in position until moved by further activation of the coil by its remote control means. To this objective, magnetic elements 22 and 23 are placed adjacent the ends of travel of the magnet 18. Element 22 is an elongated magnetic body; it may conveniently be a steel screw threaded through an aperture 24 in the rear wall 17 and provided with a jam-nut 25 for locking it in a desired longitudinal position. The slot 26 provides for simple screwdriver adjustment of the screw 22 to insure its correct positioning within the passage 19. Additionally, a bumper 27, made of a compressible material such as rubber, will cushion the end 20 and will prevent noise from the relays operation. Magnetic attraction between the magnet end pole 20 and the magnetic element 22 will thus hold the magnet 18 latched at one limit of its travel after it has been drawn there by current of a first polarity passing through the coil 13. Current of an opposite polarity through the coil 13 will then overcome the attraction between the end pole 20 and the element 22, and will move the magnet 18 toward the element 23, because of the formers asymmetrical longitudinal extent along the axis of the coil 13. The element 23, here shown as a steel plate, will now attract the end pole 21 sufficiently to latch the magnet 18 in the position shown in FIGURE 1 until this attraction in turn is overcome by further energization of the coil 13 with current of the first polarity. A compressible bumper 28 is provided to deaden switching noise. The element 23 also extends to contact the control portion 1 1 of the housing in order more completely to shield the magnet 18 aginst stray fields and in order further to enhance the effectiveness of the coil 13.

The load portion 12 of the housing 10 may contain any one of a number of conventional contact assemblies. Here, two fixed arms 29 carry a pair of contacts 30 and are affixed to the housing by a pair of molded bosses 31.

' A movable bridging contact arm 32 carrying a pair of contacts 33 on a conductive member or disc 34 makes contact between the fixed arms 29 when the insulating actuator rod 35 is drawn inward by the magnet 18. The actuator rod 35 may have threaded portions 36 for the mechanical coupling of the motion of the magnet 18 to the assembly 32; its shank 37 passes through an aperture 38 in the element 23 and through a coaxial aperture 39 in the load portion 11 of the housing 10. The high-voltage wiring 40 to the load is then attached to the arms 29 for the selective operation of the load by momentary, lowvoltage signals of proper polarity entering upon the wires 15. Complete electrical separation between the low-voltage and high-voltage portions of the relay is achieved through the use of a plastic, or insulating, actuator rod 35 and through isolation of the magnet 18 from the coil 13 by the plastic bobbin 14 and the rubber bumpers 27 and 28; shock hazard from high voltages ap pearing on the control wires is thus elfectively eliminated with a minimum of complexity and expense.

FIGURE 2 shows a variation of the relay of FIGURE 1, and shows the contact assembly 32 in a closed position with respect to the fixed contact arms 29. The magnet 18 is here mounted with a close sliding fit in an axial tube 41, which is in turn fitted into the plastic coil bobbin 14. The tube 41 fits snugly against the rear wall 42 of the housing portion 43, and is provided with a pneumatic relief hole 44. The resulting restriction of air flowing into or out of the chamber 45 thus formed between the end pole and the tube 41 slows the motion of the magnet 18 sufliciently to deaden switching noise and to eliminate contact bounce. A lubricant may be applied between the tube 41 and magnet 18 if necessary. Fabricating the tube 41 from a relatively soft metal such as brass or aluminum is advantageous in several respects. Being softer than the magnet 18 will enhance its sliding fit with the tube; and the tubes electrical conductivity will short-circuit eddy currents produced by the coil 13.

The pneumatic damping afforded by the tube 41 elim1- nates the need for bumpers on the

magnetic latching elements

46 and 47. It is still desirable, however, for a thin, nonmagnetic coating to be applied to areas of the

elements

46 and 47 adjacent the

end poles

20 and 21 of the magnet 18, in order to control the attraction therebetween, so the coil may break it on subsequent energ-ization. Alternatively, controlled latching attraction may be achieved by controlling the area of the

elements

46 and 47 which are in contact with the magnet =18. The element 47 may be an integral part of an electrical enclosure or connection box 48, the

housing portions

43 and 49 then being fastened together as at 50. Should high voltage from the wires 40 penetrate the insulating actuator rod 35, it will be harmlessly grounded through the

elements

46 or 47, or through the conductive tube 41; a possible short circuit between the coil 13 and the housing portion 43 likewise presents no hazard, since the portion 43 is grounded to the enclosure 48.

In FIGURE 3, the plastic coil bobbin 51 is fabricated to include a tubular extension 52 which carriers and guides the magnet 18. The extension 52 also positions the bobbin 51 within the low-voltage housing portion 53 so that no mechanical fastening is required to maintain the correct longitudinal relationship between the magnet 18 and the coil 13. This arrangement also provides a pneumatic chamber 54 for cushioning the movement of the magnet. Because of the type of contacts used in this embodiment of the relay, exact positioning of the limits of travel of the magnet is not required. Therefore, the magnetic latching element 55 may be a simple non-adjustable steel bottoming pin mounted by press fitting or welding through an aperture 56 in the rear Wall 57 of the housing portion 53. The magnetic element 48 is a steel disc having a diameter substantially equal to the diameter of the housing portion 53 at its open end 59. The element 58 carries a series of spaced, circumferential cars 60 which are folded to provide mounting means for the relay. The open end 59 of the housing portion 53 has a series of spaced, projecting ears 61 which fit over the circumference of the element or disc 58 and through a corresponding series of slots 62 in the high-voltage housing portion '63. When the ears 61 are bent as shown, the

housing portions

53 and 63 are locked together, so that the magnetic element 58 and the relay mounting lugs 60 "are drawn into place and the coil 13 is correctly positioned with respect to the magnet 18 by means of the tubular extension 52.

The high-voltage housing portion 63 contains a pair of bosses 64 and 65 for mounting a resilient fixed contact arm 67 and a resilient movable contact arm 66, to which the load wires 40 are afiixed. The

arms

66 and 67 are secured to the bosses 64 and 65 by means of rivets 68, fitted into recesses 69 in order to avoid shock hazard. Recesses 69 may of course be filled with an insulator such as epoxy further to reduce short circuits. The insulating actuator member 70 has a shank 71 extending through the

apertures

38 and 39 and secured at one end 72 to the magnet 18 by the spring bias of the arm 66. A head 73 then couples the motion of the magnet 18 to the resilient contact arm by means of the mechanical force exerted by the resilient arm 67 on the head 73. The wall of the aperture 39 restrains the actuator rod 70 against lateral movement.

FIGURE 4 illustrates a variation of the relay of FIG- URE 3 with the contact 74 of the arm 66 engaging the contact 75 of the stationary arm 67. It is the resiliency of the arm 67 which makes noncritical this limit of travel of the actuator member 70. The movable magnet 76 of this variation is not itself a permanent magnet, as is the magnet 18. Instead, it is a bar of magnetic material, such as soft iron, which is capable of an induced magnetic polarization. The necessary end poles in the magnet 76 are supplied exteriorly by a surrounding annular ceramic permanent magnet 77 secured to and gapped from the member 76 by the tubular extension 52 of the coil bobbin 51. This inexpensive dipole magnet 77, having

poles

78 and 79, may be held in place by a press fit, an adhesive, or a collar 80 slipped over the tubular extension 52. Thus, the magnet of the invention may be either a selfinduced permanent magnet such as that designated by the numeral 18, or an exteriorly-induced magnet such as that designated by 76. The only requirement is that it be magnetically polarized to move selectively under the influence of the polarity of current bowing through the coil 13.

FIGURE 5 depicts a relay according to the invention with suitable control and load circuits. The relay 81 may easily be fabricated to fit a standardized knock-out in a conventional electrical junction box 82. It is then held in the knock-out by the mounting lugs or ears 60 so that the entire high-voltage housing portion 63 is inside the box 82 and the low-voltage section, enclosed by the metallic housing portion 53 is outside the 'box 82 but in electrical contact with it. Since such junction boxes are commonly grounded, the housing portion 53 is also grounded, so that shock and fire hazard is eliminated even for a fault in the low-voltage control wiring within the relay 81. One high-voltage wire 40 from the relay is con-.

assembly 89. When the momentary switch lever 90 is pushed to the ON position, the contact 91 closes and negative half-cycles of the AC. waveform are passed to the relay 81 by means of the diode 92. The relay load contacts then connects the wires 40 together to energize the load 84. When the lever 90 is released, it returns to its center position as shown, but the latching action of the relay maintains the load in an energized condition. Subsequent momentary action of the lever 90 to the OFF position closes the contact 93 and thus passes positive half-cycles of the A.C. control voltage to the relay through the diode 94, which unlatches the relay, opens the connection between the wires 40, and relate hes the relay in this open condition. Releasing the lever 90 to its center position then retains the latched-open condition of the relay 81.

Having described in detail several embodiments of our novel polarized relay by way of illustration rather than by way of limitation, and also desiring to secure as our invention the novel means and instrumentalities thereof, whether or not they be used in the same fields or for the same principal objects, we claim:

1. A two-wire polarized electrical relay, comprising a single solenoidal electromagnetic coil,

a single elongated permanent magnet having a pair of end poles, said magnet being positioned axially, and longitudinally asymmetrically, within said coil for longitudinal movement with respect thereto, said magnet being drawn to a first position by a first current polarity in said coil and to a second position by an opposite polarity in said coil;

a first magnetic element adjacent a first of said end poles for latching said magnet in said first position after cessation of said first current polarity in said coil, said first magnetic element longitudinally adjustable with respect to said coil,

a second magnetic element adjacent a second of said end poles for latching said magnet in said second position after cessation of said second current polarity in said coil;

a contact assembly including a fixed contact arm and a movable contact arm, the latter being coupled to said magnet by an actuator rod, whereby movement of said magnet to one of said positions establishes an electrical connection between said contact arms, and whereby movement of said magnet to the other of said positions breaks said connect-ion and a housing having a first portion containing said contact assembly and fastened to a second portion containing said coil, magnet and magnetic latching elements, said actuator rod extending between said housing portions.

2. An electrical relay according to claim 1, wherein said first and second magnet elements each carry a bumper means for cushioning the movement of said magnet.

3. An electrical relay according to claim 2, wherein said first portion and said second portion are fastened together by cars on one of said portions fitted through slots on the other said portion and bent thereover.

References Cited UNITED STATES PATENTS 1,226,748 5/ 1917 *Burnham 335-257 1,909,665 5/ 1933 Douglas.

2,077,295 4/1937 Whitney 33561 2,212,815 8/1940 Schellenger.

2,454,973 11/1948 Mason 335-234 2,905,788 9/1959 Harrison 335187 2,919,324 12/ 1959 Schuessler 335-179 3,091,725 5/ 1963 Huston 335-230 3,202,886 8/1965 Kramer 335-234 3,217,124 11/1965 Terry 335l87 FOREIGN PATENTS 633,786 2/ 1962 Italy.

BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner