US3443253A

US3443253A - Armature damping structure

Info

Publication number: US3443253A
Application number: US598988A
Authority: US
Inventors: James E Grimes; Michael Muller
Original assignee: Babcock Electronics Corp
Current assignee: Babcock Electronics Corp
Priority date: 1966-12-05
Filing date: 1966-12-05
Publication date: 1969-05-06
Anticipated expiration: 1986-05-06
Also published as: GB1150498A; DE1589557A1

Description

Maya, 1969 J, E. GRIMES ET AL 3,443,253

ARMATURE DAMPING STRUCTURE Filed Dec. 5, 1966 Sheet I INVENTORS 47 JflMEZS E. 659/4455 y 1969 J. E. GRIMES ET AL 3,443,253

ARMATURE DAMPING STRUCTURE Filed DEC. 5, 1966 Sheet 2 of2 v I! 6/ V 3 l r i "69 INVENTORS. 779M615 f. G/Q/MES 19d? Arrows/5r United States Patent US. Cl. 335-157 10 Claims ABSTRACT OF THE DISCLOSURE An electromagnetically actuated relay having a moveable armature pivoted on a base, means on said base for dissipating as heat the kinetic energy of said armature including first and second shock dampers each having an inclined surface to engage opposite ends of said armature.

This invention relates to improvements in relays and more specifically to the prevention of armature bounce or rebounce.

The invention is applicable to relays, contactors and electromagnetically actuated devices, however named, which employ an armature whose movement is rotational and which it is desirable to keep from bouncing at the end of its stroke.

While the invention has a wide application, some of its advantages are especially apparent when applied to small and sensitive relays intended for mass production. Two such embodiments are shown in the accompanying drawings. It is to be understood that various modifications may be made in these embodiments and that other embodiments are possible without departing from the invention.

In the drawings:

FIGURE 1 is a view in front elevation of a portion of a relay embodying the invention;

FIGURE 2 is a view in side elevation of the relay portion shown in FIGURE 1;

FIGURE 3 is a top plan view taken on line 3-3 of FIGURE 2 of a fragment of the relay armature and base plate;

FIGURE 4 is a cross sectional view, taken on line 44 of FIGURE 3;

FIGURE 5 is a cross sectional view, taken on line 5-5 of FIGURE 1, showing the top of the base plate and armature;

FIGURE 6 shows the base plate in perspective;

FIGURE 7 is a top plan view of a relay embodying another form of the invention;

FIGURE 8 is a side view of the relay shown in FIG- URE 7;

FIGURE 9 is a front view of the relay shown in FIG- URE 7;

FIGURE 10 is a cross sectional view, taken on line 10-10 of FIGURE 7; and

FIGURE 11 is a perspective view of the base plate employed in the relay of FIGURE 7.

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

The relay shown in FIGURE 1 includes a contact assembly 15, a frame or base 16, actuating coils 17 and an armature 18. The contact assembly is shown in FIGURES 1 and 2 to comprise a bottom plate 19 to which a number of terminal posts 20 are fixed with insulating glass, not shown. The terminal posts extend through the bottom plate 1 9. The contacts, both fixed and movable, are formed of strips of spring material secured at one end to respectively associated ones of said terminal posts above the bottom plate. The contacts are designated by the nu- 3,443,253 Patented May 6, 1965 meral 20. Two of the terminal posts 21 are connected t( the coil 17.

The armature 18 is pivotally mounted on the frame 16 The frame comprises a pair of

side arms

22 and 23 whicl are connected at their lower ends to the bottom header plate 19. The side arms extend parallel to one anothel to a juncture above coils 17 with the magnetic core around which the coils 17 are wound. The core is C-shaped and its arms, or

pole pieces

24 and 25, extend down parallel to one another and to

side arms

22 and 23 of the frame. The plane which contains the parallel pole pieces is perpendicular to the plane which contains the parallel legs of the frame. A pivot pin is located at the intersection of the two planes. The pin is fixed at its upper end to the C-core and frame 16 and it extends downwardly on the vertical centerline of the relay. The lower end 26 has reduced diameter and extends through the pivot hole 27 of the armature. Except that the lower end 26 is shown in cross section in FIGURE 5, the pivot pin is obscured from view in the drawings. The lower tip of the pivot pin has a further reduced diameter which fits into the centering hole 28 in the center of the base plate 30 of frame 16. The centering hole is shown in FIGURE 6.

The base plate is part of the frame 16. It comprises a generally flat member. However, it has a pair of

tabs

31 and 32, one in front and one in back, which are bent down to form brackets by which the base plate is secured, as by welding, to

arms

22 and 23, respectively. The relay is assembled starting with the C-core and frame assembly. The coils 17 are assembled on the

pole pieces

24 and 25 of the core and the armature 1 8 is placed on the reduced diameter end 26 of the pivot pin. Then the base plate 30 is placed between

frame legs

22 and 23. The base plate is moved toward the armature 18 and the lower ends of the

pole pieces

24 and 25 until the pole pieces enter cutouts 34 and 35 of the base plate, and the lower tip of the pivot pin seats in centering hole 26 of the base plate. In this position the base plate lies in a plane perpendicular to the pivot pin, frame legs, and pole pieces and parallel to the plane of rotation of the armature 18. The

tabs

31 and 32 are then fixed to

legs

22 and 23. The contact assembly 15 lies below the base plate 30- and its contacts are actuated by

arms

36 and 37 which are fixed to the ends of armature 18 and extend down to the contact level where they terminate in glass beads 38 and 39' which engage the movable contacts. The upper ends of

arms

36 and 37 are flattened and secured, as by welding, to the

end flats

40 and 41, respectively, of the armature 18.

The armature 18 and the C-core including

pole pieces

24 and 25 are constructed of magnetic material. The frame 16, including the base plate 30 is advantageously formed, and in the embodiment shown is formed of nonmagnetic material. Means are provided for biasing the armature out of engagement with the

pole pieces

24 and 25. In the embodiment selected for illustration, this means comprises a leaf spring 42 and an L-shaped stop 43 formed integrally with the base plate 30 at its front edge and bent upward into a plane parallel with the

legs

22 and 23. One end 44 of leaf spring 42 is fixed, as best shown in FIGURE 5, to the side of armature 18 at the right of the pivot pin hole 27 in FIGURE 5. The other end of spring 42 bears against the stop 43 urging armature 18 out of engagement with

pole pieces

24 and 25 when they are not magnetized. The spring biases the armature into engagement with

dampers

46 and 47 located at diagonally opposite corners of base plate 30.

When coils 17 are energized,

pole pieces

24 and 25 are magnetized and attract the armature '18. Pole piece 25 attracts the right end and pole piece 24 attracts the left end, in FIGURE 5, and the armature 18 rotates counterclockwise in a plane of armature rotation perpendicular to the pivot 26. The armature rotates against the bias of spring 42 until it engages both pole pieces. The latter are placed relative to the pivot pin so that both are engaged by the armature. This rotation of the armature carries

arms

36 and 37, and particularly their glass switch actuating beads 38 and 39 into engagement with the movable contacts of the contact assembly 15. When the armature is sealed against its pole pieces the movable contacts are engaged with the normally open contacts of the relay.

When the coils 17 are de-energized, the

pole pieces

24 and 25 are demagnetized and lose their attraction for the armature. Spring 42 then rotates the armature clockwise out of engagement with the pole pieces and until the

switch actuating arms

36 and 37 and beads 38 and 39 are moved out of engagement with the movable contacts of switch assembly 15. It is required that the armature come to rest not far distant from the pole piece so that the electromagnetic force required to attract the armature is not excessive. The switch contacts must open sufficiently to prevent arcing and to insure that they will not be closed under some specified level of vibration. The armature must be retracted enough to permit that minimum switch opening. Also in the case of a relay having both normally open and normally closed contacts, such as the relay shown in the drawings, the armature must retract sufliciently to enable the movable contact to engage and seal with the normally closed contact. Thus, the armature must retract until the glass beads 38 and 39 separate from the movable contacts. Means are provided in the invention for limiting the degree of armature retraction so that spacing of the contacts and the bead actuator insures against switch actuation incident to vibration and shock but so that the air gap between the armature and its poles is not excessive. In this embodiment that means comprises the

dampers

46 and 47.

The dampers act as stops to limit armature retraction and they also serve to dissipate the kinetic energy of the retracting armature so that it does not rebound and reactuate the relay contacts. Advantageously, as shown, the stops or

dampers

46 and 47 are formed integrally with the base plate. They extend up into the plane of rotation of the armature and are formed with a sloping surface which extends through said plane. In the embodiment shown in FIGURE 4 the sloping surface 48 of stop or damper 46 slopes outward from the plane of base plate 30 and upward at an angle of about forty-five degrees. The armature 18 is rectangular in cross section and, as it retracts, its lower leading edge 49 strikes surface 48. The momentum of the armature forces it to deflect, and slide up surface 48 until the armature binds on the shoulder of its pivot pin at the top of the reduced diameter section 26 of the pivot pin. The effect is that the armature rubs against and up surface 48 and against the pivot pin shoulder so that its kinetic energy is dissipated as heat caused by friction. The two

dampers

46 and 47 are located at opposite ends and on opposite sides of the armature. Their respective sloping surfaces slope oppositely and are engaged substantially simultaneously by the armature. The tendency of the armature to be tipped by its impact with one stop is opposite to then tendency to be tipped by the other stop. The forces are balanced so the impact imposes no twisting force on the pivot pin.

In this embodiment the armature 18 has reduced width at its ends in that end portions are cut away to form the

flats

40 and 41. The shoulders that are thus formed at the juncture of the flats with the main body of the armature have surfaces 50, adjacent to flat 40, and 51, adjacent to flat 41. These surfaces lie in vertical planes that make an obtuse angle with the adjacent surface of the flats. Stated another way, the two surfaces 50 and '51 are substantially parallel to one another and they form oblique angles with a line or plane which extends through them and through the axis of pivot 26. The sloping surfaces of the dampers are oriented so that vertical projections of those surfaces lie in planes parallel to the planes of surfaces 50 and 51 when the armature is retracted back 4 against the dampers. To reiterate, the sloping surfaces of the dampers and surfaces '50 and 51 when engaged with the dampers are inclined to the plane of armature rotation in a direction intermediate the directions longitudinal and transverse to the length of the armature.

Examination of FIGURES 3 and 5, together with FIG- URE 4 shows that the dampers are engaged by a lower edge of a portion of the armature along a line which is not perpendicular to the arc of motion of the armature but lies at an angle to that arc. The two lines of contact are parallel. It was described above that the impact of the armature against one damper was balanced by impact with the other so that the net force tending to bend the pivot was zero. In the embodiment described, much of the impact momentum is directed along the armature from each end toward the other so it is converted to compression of the armature. When the armature reacts by expanding, it tends to rub up the sloping surfaces of the dampers and the energy is dissipated as heat. This arrangement in which the damping surface slopes obliquely across the plane of armature rotation damps part of the armature rotational momentum on impact and converts the remainder as compression in the armature. The latter is damped as the armature expands. Thus, the damping action is divided into two damping actions.

It is preferred that the

dampers

46 and 47 exhibit very little or no resilience. To this end the damper is advantageously formed as shown as a pyramidal boss or extrusion in which the base plate is creased along two lines extending from a point near a corner of the base plate one to one edge of the plate and the other to the adjacent edge. A third crease joins the corner with the intersection of the other two. The creases are arranged so the first two form inside corners and the third forms an outside or reentrant corner when the base plate is viewed from above as in FIGURE 5. Thus formed, one surface of the damper engages the armature and damps its motion as described and the other serves as a stiffening gusset.

Another embodiment of the invention is shown in FIGURES 7 through 11. The relay shown in these drawings comprises a contact assembly 60, a base or frame 61, an actuating coil 62, an armature 63, and a damper 64. The contact assembly includes a bottom header plate 65, connector posts 66 which extend through glass insulators, not shown, in the header plate to serve as solder terminals below and contact supports above the header plate The fixed and movable contacts 67 are fixed as by hard soldering or welding to the connector posts. Two of the posts serve as connector points for the coil 62 which in this relay is parallel with the header plate. The frame or base is generally U-shaped. It straddles the header plate and its

legs

68 and 69 are welded to the plate at points 70.

The coil 62 is lodged between

legs

68 and 69 and up against to top portion 71 of the frame. The frame is made of magnetic material and the top portion has

extensions

73 and 74 continuing from diagonal corners. Generally cubical,

magnetic pole pieces

75 and 76 are welded to the underside of these extensions, respectively. The magnetic circuit is completed by armature 63 which extends through coil 62 and is pivoted at its centerpoint on a vertical (in FIGURES 8 and 9) pivot not shown in the drawings.

When coil 62 is energized, the armature rotates about its pivot in a plane parallel to the top portion 71 of frame 61 until its ends engage the

pole pieces

75 and 76. Glass switch actuating beads 77 and 78, carried by

arms

79 and 80, actuate the relay contacts. The

arms

79 and 80 are fixed to the end of the armature 63 and extend down to the level of the contacts where they end in the glass mature. When it is retracted from its pole pieces, the armature strikes the damper.

The armature, which may be rectangular in cross section as shown, strikes along an upper edge against arm 81 and tends to be deflected downward rubbing along the surface of the arm. Friction in this action dissipates kinetic energy of the armature as heat energy. Almost simultaneously the armature strikes along its lower edge against the damper arm 82 and tends to be deflected upward rubbing along the surface of the arm dissipating kinetic energy as heat. Whether initial net deflection is up or down the impact and rubbing is repeated when the armature strikes the other arm the process of converting kinetic energy to heat is repeated. Which arm is first contacted by the armature is a function of tolerance and fit in manufacture and environmental conditions such as vibration, acceleration, magnetic and gravitational fields and so on. It is not material which arm is first struck or whether they are struck simultaneously.

Advantageously the damper exhibits little or no resilience. Accordingly, it is fixed to a bracket 87 formed integrally with frame 61 and bent into position to hold the stop or damper 64 in the plane of rotation of the armature 63, and to limit armature retraction to a point at which the glass beads clear the movable relay contacts. The armature is biased to its retracted position by a leaf spring 88 which is fixed to the armature near its midpoint and has its outer end trapped behind the damper bracket 87.

Although we have shown and described certain specific embodiments of our invention, we are fully aware that many modifications thereof are possible. Our invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

We claim:

1. In a relay, an electromagnetic actuator comprising a base, an armature pivotally mounted on said base, electromagnetic means for rotating said armature in a plane from one position to another, means for biasing said armature to said one position, and means for dissipating as heat the kinetic energy of said armature including first and second shock dampers secured relative to said base at said one position and each having a sloping surface extending across said plane in a direction tending to deflect said rotating armature from said plane, the surfaces of said dampers being sloped oppositely whereby the tendency of each to deflect said armature is opposed by the other.

2. The invention defined in claim 1 in which said armature is pivotally mounted at its midpoint and said dampers are disposed to engage the opposite ends of said armature, respectively.

3. The invention defined in claim 2 in which said dampers are formed integrally with said base and are relatively nomresilient.

4. The invention defined in claim 1, in which sai base is formed of sheet metal and said dampers are forme as portions bent out of the plane of said sheet.

5. The invention defined in claim 1, in which said slop ing surfaces of the dampers are inclined to said plane 0 movement of the armature in a direction intermediate th directions longitudinal and transverse to the armature whei in said one position.

6. The invention defined in claim .1 in which sair dampers comprise the arms of a V-shaped membe secured to said base and disposed to engage one end 0: said armature between them.

7. In a relay, an armature, means mounting said arma ture for rotation in a plane about a central axis of S21l( armature, and means for limiting rotation of said arma ture in one direction while dissipating its kinetic energy comprising a pair of stops each having a sloping surface inclined to said plane, said inclined surfaces being disposed to engage opposite ends of said armature and having opposite inclination relative to said plane whereby the tendency of each to deflect the armature from said plane is opposed by the other. 1

8. The invention defined in claim 7, in which the portions of said armature engageable with said stops are formed with edges parallel each to the other on a line which forms an oblique angle with a line extending through said axis and intersecting said edges, and the sloping surfaces of said stops being inclined to engage said armature along said edges.

9. The invention defined in claim 7, including a base plate disposed parallel to said plane, said stops being formed as surfaces of said base plate extending across said plane.

10. The invention defined in claim 8, including a base plate disposed parallel to said plane, said stops being formed as pyramidal bosses bent to have one surface sloped and inclined to engage the armature along said edges and to have another surface extending in another direction and joining said one surface of said tab with said plate whereby to reinforce said one surface against resiliently yielding to impact of said armature.

References Cited UNITED STATES PATENTS 2,863,103 12/1958 Tancred 335277 3,147,349 9/1964 Welch 335- 3,283,272 11/1966 Garratt 335-193 BERNARD A. GILHEANY, Primary Examiner. H. BROOME, Assistant Examiner.

US. Cl. X.R. 335-193, 277