US3248499A

US3248499A - Electro-mechanical actuator with permanent magnet

Info

Publication number: US3248499A
Application number: US223331A
Authority: US
Inventors: Edward J Young
Original assignee: DIGITAL ANALOG TECHNICAL ASSOC
Current assignee: DIGITAL ANALOG TECHNICAL ASSOC; DIGITAL ANALOG TECHNICAL ASSOCIATES Inc
Priority date: 1962-09-13
Filing date: 1962-09-13
Publication date: 1966-04-26
Anticipated expiration: 1983-04-26

Description

April 26, 1966 E. J. YOUNG 3,248,499

ELECTRO-MECHANICAL ACTUATOR WITH PERMANENT MAGNET Filed Sept. l5, 1962 5 Sheets-Sheet 2 April 26, 1966 E. J. YOUNG 3,248,499

ELECTRO-MECHANICAL ACTUATOR WITH PERMANENT MAGNET Filed Sept. 13, 1962 3 Sheets-Sheet 5 Ff. y 132 156 "42 lf2 .X24 15.5

United States Patent O 3 248,499 ELECTRO-MECHACAL ACTUATR WITH PERMANENT MAGNET Edward l. Young, Hawthorne, Calif., assignor to Digital Analog Technical Associates, Inc., El Segundo, Calif.,

a corporation of Caiifornia Filed Sept. 13, 1962, Ser. No. 223,331 17 Ciaims. (Cl. 20d- 93) This invention relates to an actuator employing magnetic force and, more particularly, pertains to such a device which employs a movable armature for an actuator and incorporates permanent magnet means for releasably maintaining the armature at one of its two alternate positions. Such an actuator may be used for various purposes including the remote operation of valves but has special usefulness in switch mechanisms.

Gne of the appli-cations of the invention wherein it has special utility is an electromagnet binary relay capable of :operation at much higher speeds than conventional relays. The invention is also applicable to the construction of a monostable relay. In addition, certain principles of the invention may be embodied in a push button switch, which switch may, if desired, be adapted for remote actuation as well as manual actuation.

With reference to the embodiment of the invention as an electromagnetic binary relay, it is well known that an electromagnetic relay with a movable armature, as distinguished from a purely electronic relay with no moving parts, is desirable for many uses because such a relay may be of rugged construction and may operate in a positive manner with substantial actuation force. Conventional electromagnetic relays, however, are bulky, relatively expensive and inherently slow in operation. While no mechanical electromagnetic relay with a movable armature can operate in microseconds to compete in speed with purely electronic relays, nevertheless, there is a definite need for an electromagnetic relay such as a binary relay, that can operate in microseconds. The present invention meets this demand with a highly reliable binary relay that is of miniature size, of simple inexpensive construction, immune to shock and vibration, and is capable of operation at a rate of 2,00() or more times per second.

Generally described, the binary relay of the invention has a ferromagnetic structure including permanent magnet means and two spaced confronting pole pieces with an armature movably mounted in the gap between the confronting pole pieces. The permanent magnet means creates a normal magnetic field in the ferromagnetic structure with concentrated iiux across the gap and through the armature to cause the armature to adhere magnetically to whichever pole piece it may abut. The use of an armature of small mass in a high concentration of magnetic flux causes the armature to be latched at its two opposite stable positions with a latching force capable of withstanding exceedingly high shock forces along its operating axis.

Associated with the ferromagnetic structure is an electromagnetic coil means capable of overcoming the normal magnetic field created by the permanent magnet means. Remotely controlled means energizes the electromagnetic coil means reversibly to shift the armature reversibly across the gap between the two pole pieces.

Preferably, a concentric arrangement is used with the two pole pieces and the intervening armature aligned along an axis and surrounded by two substantially coextensive annular means, one annular means being the permanent magnet means and the other annular means being the electromagnetic coil means. The permanent magnet means must be outermost.

"ice

In the preferred practice of the invention the fer-romagnetic structure includes two aligned oppositely polarized cylindrical permanent magnets which may be termed right hand and left hand magnets and two corresponding left hand and right hand coils inside the cylindrical magnets with two corresponding right hand and left hand axial pole pieces inside the two coils respectively. The two cylindrical permanent magnets create two opposite toroidal magnetic fields with concentrated flux in the region of the armature and the two coils act as `one coil and are reversible to create a reversible controlling magnetic field. Current iiow in one direction through the two coils weakens or nullities the field of the right hand magnet and simultaneously reinforces the field of the lefthand magnet to cause the armature to shift with a snap action from the right pole piece to the left pole piece. In like manner reverse current iiow weakens or nullifies the iield of the left hand magnet and augments the lield of the right hand magnet to shift the armature from its left hand position to its right hand position.

In a second embodiment of the binary relay, at least one cylindrical permanent magnet is provided to create a single toroidal magnetic field through the two confronting axial pole pieces to latch the armature at its two positlons. Two opposed annular coils are provided to create two `opposite control fields, the coil current iiow being reversible to reverse the two bucking control fields for shifting lthe karmature selectively in its two opposite directions.

As will be explained, a feature of the invention is the employment of resilient switch arm means that is stressed in iiexure for creating desirable contact pressure. Preferably associated inclined cam surfaces are provided for urging and holding the switch arm means against th cooperating contact means.

With reference to the utility of the invention in the construction of push button switches, one such switch described hereinafter employs a permanent magnet to maintain a movable switch member in a normal position and the switch member is shifted to its alternate position by a manually operable push button. In the selected embodiment of the invention, electromagnetic vmeans under remote control may also be available to shift the switch member to its alternate position.

In a second embodiment of a push button switch, two permanent magnets releasably latch a switch member at whichever of its two alternate positions it may be placed. 'Two switch buttons are adapted to shift the switch member mechanically to its two alternate positions respectively and, in addition, remotely controlled elec-r tromagnetic means may be provi-ded to shift the switch member to its two alternate positions respectively.

The features and advantages of the invention may be understood from the following detailed description and the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative:

FIG. l is a longitudinal sectional view of the presently preferred embodiment of the invention with the switch structure omitted for clarity;

FIG. 2 is an exploded view of the functional parts shown in FIG. l;

FIG. 2a is a diagrammatic View showing the configuration of the magnetic fields created in the operation of the binary relay;

FIG. 3 is a side elevation of the binary relay on a reduced scale with the sealed housing or casing for the relay shown in phantom;

FIG. 4 is an end elevation of the binary relay on a somewhat enlarged scale asseen along the line 4--4 of FIG. 3 showing the switch structure;

FIG. 5 is a greatly enlarged View, partly in section and partly in side elevation, of the structure of the stationary contacts of the double pole switch, the section being taken along the angular line 5-5 of FIG. 4;

FIG. 5a is a fragmentary sectional view showing how two opposite cam surfaces cooperate with a spring wire switch arm;

FIG. 6 is a simplified sectional view of a second embodiment of the invention; A

FIG. 6a is a diagram showing the configuration of the magnetic fields that are involved in the operation of the second embodiment of the invention;

FIG. 7 is a simplified sectional View of a third embodiment of the invention in the form of a relay;

FIG. 8 is a longitudinal sectional view showing how the principles of the invention may be embodied in a push button switch which is adapted for operation also by remote control; and

FIG. 9 is a view partly in side elevation and partly in section showing how the principles of the invention may be embodied in a double acting push button switch which is adapted for operation also by remote control.

The first embodiment of the invention comprises a cylindrical functional assembly which is mounted in a sealed casing. As indicated in FIGS. 1 and 3, the cylindrical functional assembly includes: a central axial tube 10 of a suitable smooth plastic such as Teflon or other nonmagnetic material; a spaced pair of coaxial coils comprising a left hand coil 12 and a right hand coil 13 surrounding the tube 10; a central ferromagnetic disk 14 with a central aperture 15 to receive the tube 10; a pair of cylindrical permanent magnets abutting the opposite faces of the disk 14 comprising a left hand magnet 16 and a right hand magnet 18; a left hand pole piece 20 having an axial extension 22 in the tube 10; aright hand pole piece 24 in the form of a disk having an axial extension 25 in the tube 10, the two axial extensions of the two pole pieces being spaced apart to form a gap or working space between the two pole pieces; an actuating armature 26 slidingly mounted in the gap between the two pole pieces; and an operating member 28 in the form of a push-pull rod which extends through an axial bore or passageway 30 in the right hand pole piece 24. The operating member 28may comprise a piece of piano wire having a high resistance to magnetic fiux.

It is apparent that the central disk 14, the two

cylindrical magnets

16 and 18, and the two

pole pieces

20 and 24 form a compact cylindrical ferromagnetic structure for creating a high concentration of magnetic fiux in the region of the armature 26. The normal magnetic pattern created by the two magnets comprises two opposite toroidal fields and it is apparent that the central disk 14 has the important function of concentrating the flux of both fields in the region of the armature 26.

In this particular embodiment of the invention the armature 26 acting through the operating member 28 actuates a double-pole, double-throw switch. For this purpose two spaced

switch arms

32 and 34 in the form of reresilient wires (FIGS. 1 and 4) are actuated by an operating head 35 on the outer end of the operating member 28, each of the two switch arms cooperating with two spaced

fixed switch contacts

36 and 38 which are shown in FIG. 5. In the construction shown the components of the double pole switch are mounted on four screws 40 which extend longitudinally outward from the right hand pole piece 24.

The described parts of the ferromagnetic structure fit together metal to metal in a compact assembly which in the course of the assembly procedure is confined inside a sleeve 42 made of nonmagnetic material which may be aluminum. One end of the aluminum sleeve 42 is swaged to form an inner circumferential bead 44 in engagement with one end of the ferromagnetic structure and a second similar swaged bead 45 engages the other end of the ferromagnetic structure. As may be seen in FIG. l, a portion of the aluminum sleeve 42 extends beyond the inner bead 45 to enclose the double pole switch, this end portion of the aluminumsleeve being provided with two opposite windows or apertures 46. The two ends of the sleeve 42 are closed by aluminum headers 48 which may be brazed thereto, one header having electrical terminals 50 mounted therein in a sealed manner for connection to the two coils, the other header having additional electrical terminals for the switch contacts. A cylindrical housing 52 made of non-magnetic metal such as aluminum completely encloses both the sleeve 42 and the two headers 48 and is brazed or otherwise bonded at itsv ends to the two headers.

As indicated in FIGS. 3 and 4 the two

resilient wires

32 and 34 which form the two switch arms of the switch are rigidly mounted at their fixed ends between two blocks 62 of insulating material. The two blocks 62 are mounted on the outer surface of the right hand pole piece 24 by two of the four screws 46, the two blocks being clamped together by means of nuts 66 on the screws. As shown in FIG. 1, the operating head 35 is of circular construction with a circumferential groove of V-shaped configuration that provides two opposite conical cam surfaces 65 and 66 for acting on the two

wire'switch arms

32 and 34.

The two pairs of fixed

contacts

36 and 38 to cooperate with the two

wire switch arms

32 and 34 respectively, are mounted on the remaining two screws 40 in the manner shown in FIGS. 4 and 5. Each of the two screws is surrounded by'a thin insulating sleeve 71. An inner block 68 of insulating material and a similar outer block '70 are mounted on the two sleeves 71 with two Contact assemblies sandwiched between the two blocks on each of the two sleeves. Each of the two contact assemblies comprises a fiat wiring terminal 72, a previously mentioned contact 38, an insulating washer 74, a previously mentioned contact 36 and a second fiat wiring terminal 75, all of which have apertures or bores that are oversized to permit lateral adjustment of the parts of the assembly in the screw. When the two contact assemblies are properly adjusted, nuts 64 are tightened on the two screws to clamp the parts in a rigid manner.

It is apparent that thetwo contact assemblies comprising the two contacts 36, the two contacts 38 and the two intervening insulating washers 74 constitute. two guide structures for the two resilient wire switch

arms

32 and 34. These two guide structures, which include the fixed contacts, straddle the two resilient wire switch arms and the two switch arms, in turn, straddle the operating head 35. The two guide structures are adjusted eccentrically of the corresponding screws 46 to crowd and flex the two switch arms against the operating head.

As shown in FIG. 5, the inner insulating block 68 is formed with an outwardly extending tapered boss 76 that provides a conical cam surface or guide surface 78 adjacent the two inner fixed contacts 38 and in like manner extending tapered boss 80 that provides a conical cam surface or guide surface 82 adjacent the two outer fixed contacts 36.

The manner in which the described invention serves its purpose may be readily understood from the foregoing description. Normally the two

coils

12 and 13 are deenergized and the normal iiux pattern created by the two

permanent magnets

16 and 18 consists of two opposite toroidal magnetic fields. FIG. 2a shows two sets of circular arrows 84 representing the left hand toroidal magnetic field created by the left hand magnet 16 and shows two sets of arrows 85 representing the right hand toroidal magnetic field created by the right hand permanent magnet 18.

When the two

coils

12 and 13 are energized to shift the armature 26 from its right hand position shown in FIG. 1 to its alternate left hand position, the current fiow which is in the same direction through the two coils creates a single overall toroidal control field indicated by the arrows 86 in FIG. 2a. It is apparent that the control field indicated by the arrows 86 is opposed to the 'right hand normal field 85 to weaken if not completely cancel the attraction force between the armature 26 and the right hand pole piece 24. It is further apparent that af the same time the arrows S6 representing the overall control field are in the same direction as the left hand arrows 84 representing the left hand normalfield. Thus, the overall control field is additive with respect to the left hand normal field represented by the arrows 84 and greatly augments the left hand normal field to cause the armature 26 to be attracted with a snap action to the left hand pole piece 20. In like manner, energizing the two

4control coils

12 and 13 in the opposite respect weakens if not cancels out the left hand normal field represented by the arrows 8d and augments the right hand normal field represented by the arrows 85 to cause the armature to snap over to the right hand pole piece 24.

When the armature 26 is at its right hand position as viewed in FIG. l, the two

wire switch arms

32 and 34 are in the position shown in solid lines in FIG. 5. In FIG. 5 it is apparentthat the conical cam surface 82 of the boss 8l) wedges the

wire spring arms

32 and 34 snugly against the corresponding switch contacts 36. FIG. 5a shows how at this time the conical surface 66 of the operating head 35 cooperates with the conical cam surface 32 of the boss 80. Itis to be noted in FIG. 5a that the switch arm 32 is not in the bottom of the recess that forms the two

cam surfaces

65 and 66 of the operating head 35. The wire switch arm 32 is flexed laterally by the cam surface 66 of the operating head. Thus the operating head by its cam surface 66 tends to spread the two

wire switch arms

32 and 34 apart and in doing so liexes the wire switch arms to cause them to exert pressure against the two lfixed switch contacts 36. In like manner when the armature 26 abuts the left hand pole piece 20, each of the two

wire switch arms

32 and 34 is forced by the second cam surface 65 of the operating head 35 into wedging position between the cam surface 78 of the boss 76 and the corresponding fixed contacts 38.

Even without the two bosses 76 and 80, the two

wire switch arms

32 and 34 would exert pressure against the fixed

contacts

36 and 38 by virtue of the two conical surfaces and 66 of the operating head 35 and especi-ally so because the fixed

contacts

36 and 38 and the intervening insulating washers 74 are adjusted to flex the two wire switch arms against the operating head. It is to be noted that the two wire switch arms cannot lie at the bottom of the recess that forms the two

cam surfaces

65 and 66 of the operating head 35 unless the two wire switch arms are perpendicular to the taxis of the operating head and this condition occurs only momentarily as the two wire switch arms swing between their limit positions. At their limit positions the two wire switch arms are nonperpendicular to the axis of the operating head 35 and therefore are out of the bottom of the recess, the two wire switch arms being thus flexed by the operating head for increased contact pressure.

To achieve the desired high operating speed, the mass of the armature 26 is relatively small, the range of travel of the armature is relatively short and Ithe magnetic iiux is highly concentrated in the region of armature travel. In one successful embodiment of the invention the armature 26 combined with the operating rod 28 and the operating head 35 has a total weight of only 1A gram, the travel of the armature between i-ts two opposite lim-it positions is only .010 inch and the magnetic force that holds the armature against a pole piece is on the order of 300 grams. This holding force is sufficient t-o withstand a force of over 1200 G along the axis of movement of the armature and the armature is immune to G forces that are exerted transversely of its axis of movement.

Reliability over an extended service period of a high number of cycles requires that the two switch arms maintain continuous contact with the fixed

contact elements

36 and 38 whenever the switch arms are moved into the range of the fixed contact elements. If continuous contact is not maintained, spark erosion will develop and -the galled metal wiil then cause 4the switch arms to jump with consequent interrupting of the current. Plating or alloying the fixed contacts and/ or switch arms with a noble metal is helpful for preventing oxide formation or other insulating films, but of equal importance are the described mechanical provisions for causing the two resilient wire switch arms to exert wiping pressure against the fixed contacts.

The second embodiment of the invention shown diagrammatically in FIG. 6 is largely similar to the first embodiment of the invention 4as indicated by the use of corresponding numerals to indicate corresponding parts. Here again a left hand permanent magnet 16a and a right hand permanent magnet 18a cooperate with two pole pieces 20a and 24a to form a ferromagnetic structure to yieldingly hold an armature 26a to two opposite lim-it positions. The two magnets are sho-wn separately by a ferromagnetic ring which corresponds to the previously mentioned disk 14. Inside of the two permanent'

magnets

16a and 13a are corresponding

coils

12a and 13a.

The second embodiment of the invention differs from the first in that the two permanent magnets y16a and 18a cooperate to form a single toroidal magnetic field instead of two opposite magnetic fields and the two

coils

12a and 13a create two opposite toroidal control Ifields instead of a single overalll control field. In FIG. 6a the outer arrows `92 indicate the normal overall magnetic field created by the two

permanent magnets

16a and 18a. gized in one respect they create two opposite toroidal control fields of flux indicated by the inner arrows 94 and -95 respectively. it `will be noted that the right hand control field indicated 'by the arrows 95 augments the portion of the normal ttield that is created by the right hand permanent magnet 18a while the left hand control field indicated by vthe arrows A94- diminishes or nullifies the portion of the normal eld that is created by the left hand permanent magnet 16a. Consequently, the armature y26a is shifted from its left hand position to its right hand position. It is apparent that if the current ilow through the two coils is reversed the two control fields are reversed to cause the armature to shift to the right by weakening the portion of the normal field that is created by the left 'hand' permanent magnet and augmenting the port-ion of the normal eld that is created by the right hand permanent magnet. It is apparent that, if desired, the central spacer ring 90 may be omitted with a single cylindrical electromagnet substituted for the pair of cylindrical electromagnets.

It is to be noted that in -both of the described embodiments of the invention, the actuating armature is latched in its two alternate llimit positions by the magnetic force created by the permanent magnets. Thus no outside power is required for holding the armature.

It Iwill be readily appreciated by lthose skilled in the art that either of the two described bistable devices may be employed las -a chopper. Special advantages of such a chopper are minimum noise and absence of bounce.

IFIG. 7 indicates the manner in which the principles of the inventon may be incorporated in a -monostable device. In thi-s instance the monos-table device may be Ia relay with the previously described contact arrangement or with any other desired contact arrangement.

The cylindricatl assembly shown in fF-IG. 7, which may be suitably encased as previously described, includes: the usual central axial tube of a Suitable smooth plastic such as Teon; a spaced pair of coaxial coils cornprising a left hand coil 112 and a right hand coil |113 both surrounding the tube 110; a central ferromagnetic disk 1114 with a central aperture to receive the tube When the

Atwo control coils

12a and 13a are ener- 110; a single right hand cylindrical permanent magnet 116; a spacer sleeve 118 of non-magnetic material such as aluminum or brass; a left hand pole piece 120 having `an axial extension 122 in the tube 111i; a right hand pole piece '124 having an axial extension 125 in the tube 110, the two axial extensions of the two pole pieces being spaced apart to form a gap or working space between the two pole pieces; an actuating armature 126 slidingly mounted inthe gap between the two pole pieces; and an operating member 128 which extends through an axial bore `130 in the right hand pole piece `124 and which operates a switching mechanism in the previously described manner.

In the absence of energization of the two

coils

112 and 113 the normal toroidal magnetic field created by the single permanent magnet `116 attracts the armature 126 and holds the armature `126 at its normal right hand position as shown in FIG. 7. When the two coils i112 and 113 are energized, `the right hand coil i113 Iweakens or cancels the normal magnetic field created by the permanent magnet l116 yand the left hand coil 112 creates a toroidal magnetic field to attract the armature 126 out of lits normal position to Vits left hand limit position. When the current flow through the two coils terminates, the armature 126 snaps back to its normal right hand position.

FIG. 8 shows how the principles of the invention may be applied to the construction of a push button switch. The structure shown in FIG. 8 is in large part similar to the construction of the mono-stable device or relay shown in FIG. 7, as indicated by the use of corresponding numerals to indicate corresponding parts. It may be seen in FIG. 8 that an actuating armature 126 is mounted in the previously described manner in a ferromagnetic structure that includes the two pole pieces 1211 and 124. The operating member 128 that extends through `the bore 131) in the pole piece 1241 functions in the previously described manner to control at least one switch arm. FIG. 8 shows the operating member 128 carrying a previously described operating head to control two

switch arms

32 and 34.

The ferromagnetic structure in FIG. 8 is mounted in a. casing comprising a cylindrical shell 132 and two

end walls

134 and 135 in the form of discs. The cylindrical casing provides a compartment 136 for the switch mechanism including the two

switch arms

32 and 34. The operating member 12S that carries the operating head 35 extends beyond the operating head through a bore in the end wall 135 to an exterior push button 138. The push button 13S is normally held at an outer position by a concealed coil spring 140 and is retained by a radially inward flange 142 of the cylindrical shell 132. The flange 142 extends into an outer circumferential groove 144 of the push button, the groove being substantially wider than the thickness of the flange to permit the required range of axial movement of the push button.

The push button switch shown in FIG. 8 includes the previously described

coils

112 and 113. When the two

coils

112 and 113 are energized, the right hand coil 113 weakens or cancels the normal magnetic field created by the permanent magnet 116 and the ,left hand coil 112 creates a toroidal magnetic field to attract the armature 126 out of its normal position to its left hand limit position. When the current flow through the two coils terminates, the armature 126 is snapped back to its normal right hand position by the magnetic field of the permanent magnet 116. The push button 138 may be manually depressed as an alternate means for shifting the armature 126 out of its normal position to its left hand position.

In FIG. 9 illustrating the application of the invention to the construction of a dual push button switch the construction is largely similar to the previously described construction shown in FIG. l, as indicated by the use of corresponding numerals to indicate corresponding parts. The structure mounted in the cylindrical housing 52a differs in only two respects from the structure mounted in the cylindrical housing 52 in FIG. l. One difference is that the axial extension 22 of the left hand pole piece 20 is provided with an axial bore 145 to receive in a sliding manner an operating member 146 which is of the same character as the operating member 28 in FIG. l. The second difference is that the operating member 146 which carries the operating head 35 extends at both of its ends through bores in the two headers 48 with substantial end portions of the operating member exposed outside the two ends of the cylindrical housing.

The cylindrical housing 52a is adapted by suitable means (not shown) for support adjacent a panel 148 which has two spaced apertures 150 to clear two push buttons 152 and 154. The two push buttons are mounted on the opposite ends respectively of a yoke 155 that has two

arms

156 and 158 overhanging the opposite ends of the operating member 146. The yoke 155 is pivotally mounted on a bracket 159 on the cylindrical housing 52a and is normally held at an intermediate or neutral position by the two arms of a leaf spring 160.

In the previously described manner, the two

coils

12 and 13 may be energized selectively by remote control to cause the armature 26 to shift to its two alternate positions selectively but the armature 26 may also be shifted by manual operation of the two push buttons. With the parts positioned as shown in FIG. 9, depression of the switch button 154 rocks the yoke 155 to cause the yoke arm 153 to shift the operating member 146 to the left, thereby to shift the armature 26 from its'right hand limit position to its left hand limit position. Subsequently the switch button 152 may be depressed to shift the armature 26 back to its right hand position. Thus, two switch

arms

32 and 34 associated with the operating head 35 may be actuated either by remote controlv or by manual push button control.

If desired, the

coils

112 and 113 may be omitted from the push button structure shown in FIG. 8 and the

coils

12 and 13 may be omitted from the push button structure shown in FIG. 9. Thus both of these embodiments of the invention may beadapted to serve as simple manual controls only.

My description in specific detail of the selected practices of the invention will suggest various changes, substitutions and other departures from my disclosure without departing from the spirit and scope of the appended claims. l

I claim:

1. In an actuator of the character described, the combination of:

ferromagnetic means including two opposite pole pieces having confronting spaced axially aligned portions forming a working gap;

an armature to serve as an actuator, said armature being mounted in said gap for movement between two alternate limit positions against said two pole .pieces respectively;

two coils surrounding said portions of the two pole pieces respectively; and

two cylindrical permanent magnets surrounding said two coils respectively, to create two opposed magnetic fields to cause said armature to be held magnetically against whichever pole piece it may be positioned, said two coils being cooperative to form a single controlling magnetic field, said two coils being adapted for energization in opposite respects selectively to shift said armature across said gap against the two pole pieces selectively, said two permanent magnets carrying the outermost flux paths in the operation of the device.

2. In an actuator of the character described, the combination of:

an armature to serve as an actuator, said armature being mounted in said gap for movement between two alternate limit positions against said two pole pieces respectively; l

two coils surrounding said portions of the two pole pieces respectively; and

two cylindrical permanent magnets surrounding said two coils respectively to hold said armature against whichever pole piece it may be placed, said permanent magnets being of the same polarity to create a single magnetic field, said two coils being opposed for energization in two respects selectively to shift said armature across the gap to the two pole pieces selectively.

3. In an actuator of the character described, the combination of:

an armature to serve as an actuator, said armature `being mounted in said gap for movement between two alternate limit positions against said two pole pieces respectively;

two coils surrounding said two portions of the two pole pieces respectively; and

a cylindrical permanent magnet surrounding one of said coils to -create a normal magnetic field for normally holding said armature against the corresponding pole piece, said two coils being opposed for energization in one respect to cause the coil surrounded by the permanent magnet to o-ppose said magnetic field to reduce the attraction of said corresponding pole piece for the armature land to create a second magnetic field associated with the other pole piece to attract the armature to the other pole piece.

4. In a device of the character described, the combination of:

an armature reciprocative between two alternate limit po-sitions;

ferromagnetic means including two spaced confronting pole pieces forming a working gap;

permanent magnet means magnetically linked with at least one of said two pole pieces to yieldingly hold the armature against said one pole piece;

electromagnetic means to shift the armature across the working gap;

an operating member mechanically connected to said armature to move between two corresponding limit positions, said operating members having a peripheral recess with one side of the recess forming a cam surface;

a fixed contact;

a swingable switch arm cooperative with said contact to open and close a circuit, said switch arm extending into said recess for movement of the switch arm by the operating member between two corresponding limit positions, said contact being on the side of the switch arm opposite from the operating member and said cam surface of the operating mem- Iber being positioned to cam the switch arm against said contact at one of the two limit positions of the switch arm.

5. A combination as set forth in claim 4 which includes means providing a fixed guide surface in convergent relation to said contact and in the path o-f the movement of the switch arm for additionally camming the switch arm against the contact.

6. In a device of the character described, the com bination of:

an armature reciprocative between two alternate limit positions; ferromagnetic means including two spaced confronting pole pieces forming a workin-g gap; permanent magnet means magnetically linked with at least one of said two pole pieces to yieldingly hold the armature against said one pole piece;

electromagnetic means to shift the armature across the working gap;

an operating member mechanically connected to said armature to move between two corresponding limit positions;

a fixed contact;

a swingable switch arm cooperative with said contact to open and close a circuit, said switch arm being operatively connected to said operating member for movement of the switch arm by the operating member between two c-orresponding limit positions, one of said limit positions `of the switch arm being at said fixed contact; and

means providing a fixed guide surface in convergent relation to said fixed contact and in the path of movement of the switch arm for camming the switch arm' against the contact.

7. In a device of the character described, the `combination of:

anarmature reciprocative between two alternate limit positions;

electromagnetic means to shift the armature across the working gap;

an operating means mechanically connected to said armature to move between two corresponding positions, saidoperating means having a pair of opposite surfaces;

a pair of swingable resilient switch arms loperatively connected to said operating means for movement thereby to corresponding limit positions; and

fixed 'guide struct-ure having a pair of guide surfaces :for said switch arms, said guide structure including yfixed contacts for cooperation with the switch arms `at limit positions of the switch arms, said pair lof guide surfaces straddling the pair of switch arms and the switch arms straddling the pair of opposite surfaces of the operating means, at least one of the two lpair of surfaces being inclined for fiexure of the switch arms into pressure contact with the guide structure.

8. A combination as set forth in claim 7 in which said operating means has recesses on its opposite sides receiving the switch arms for operation thereof, said recesses being tapered for cam action against the switch arms at limit positions of the switch arms.

9. A combination as set forth in claim -in which the pair o-f guide surfaces of .the guide structure are also inclined to cam the switch arms against the contacts as the switch arms approach the contacts.

l10. In an actuator of the character described, the combination of:

an armature to serve as actuator means, said armature being reciprocative between two limit positions; magnetic means having two confronting poles at the two limit positions respectively of the armature to yieldingly hold the armature at whichever of the two limit positions it may occupy;

electromagnetic control means to create two opposite controlling magnetic fields :selectively to selectively cooperate with the permanent magnetic fields to shift the armature to its two limit positions selectively;

a switch arm operatively connected to said operating means for movement thereby to corresponding limit ipositions;

a fixed contact for cooperation with said switch arm at a limit position thereof; `and a fixed cam adjacent said fixed contact to cam the .switch said ferromagnetic structure enclosing the two coilsand a portion of the ferromagnetic structure extending radially inwardly between the two coils to said gap; and two cylindrical permanent magnets in said ferromag netic structure surrounding the two coils respectively to hold said armature against whichever pole it may be placed,

said two coils being adapted for energization in opposite respects selectively to shift said armature Iacross said gap to its two limit `positions selectively,

said two :permanent magnets enclosing the outermost paths of magnetic llux of the device, said two pole pieces extending axially a substantial distance inward into the interiors of the corresponding coils to reduce the axial dimension of said gap,

said armature being` correspondingly reduced in axial dimension to reduce the mass of the armature and thereby reduce the inertia of the armature to permit the armature to shift between its alternate limit positions in a time interval of less than IAOOO of a second.

12. A combination as set forth in claim .11 in which said two permanent magnets are of opposed polarity and in which said two coils are cooperative in their effect on the armature.

13. A combination as set forth in claim 11 in which said two permanent magnets are of the same polarity to create a single magnetic -eld and in which said two coils are opposed.

14. A combination as set forth in claim 11 which includes manual means to shift said armature from one `of said pole pieces to the other.

15. A ycombination as set forth in claim 14 in which said manual means comprises a .push button operatively connected to said armature to shift the armature from one limit position to the other in opposition to the holding magnetic uX.

`16. A combination as set forth in claim 14 in which said manual means comprises two tpush buttons operative to shift said armature in its opposite directions respectively.

17. A combination as set forth in claim 11 which includes:

a 4plastic .sleeve enclosing said gap, said sleeve slidingly embracing said arma-ture to guide the armature with low frictional resistance.

References Cited by the Examiner UNITED STATES PATENTS 1,572,708 2/ 1926 Eaton 200-87 2,505,904 5/1950 Matthias et al 317-172 2,591,336 4/1952 Bordelon 200-87 2,769,103 10/ 1956 Kristiansen 317-172 2,919,324 12/ 1959 Schuessler 200-93 3,017,476 1/ 1962 Becka 200-153 3,022,450 2/196'2 Chase 317-171 3,030,469 4/1962 -Lazich 317-171 X 3,040,217 6/1962 Conrad 317-172 3,070,730 12./1962 Gray et al 317-171 3,105,925 10/1963 Musgrave 317-171 3,119,940 1/1964 Pettit et al 317-171 X BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

Claims

1. IN AN ACTUATOR OF THE CHARACTER DESCRIBED, THE COMBINATION OF: FERROMAGNETIC MEANS INCLUDING TWO OPPOSITE POLE PIECES HAVING CONFRONTING SPACED AXIALLY ALIGNED PORTIONS FORMING A WORKING GAP; AN ARMATURE TO SERVE AS AN ACTUATOR, SAID ARMATURE BEING MOUNTED IN SAID GAP FOR MOVEMENT BETWEEN TWO ALTERNATE LIMIT POSITIONS AGAINST SAID TWO POLE PIECES RESPECTIVELY; TWO COILS SURROUNDING SAID PORTIONS OF THE TWO POLE PIECES RESPECTIVELY; AND TWO CYLINDRICAL PERMANENT MAGNETS SURROUNDING SAID TWO COILS RESPECTIVELY, TO CREATE TWO OPPOSED MAGNETIC FIELDS TO CAUSE SAID ARMATURE TO BE HELD MAGNETICALLY AGAINST WHICHEVER POLE PIECE IT MAY BE POSITIONED, SAID TWO COILS BEING COOPERATIVE TO FORM