US2628272A - Electromagnetic actuator - Google Patents

Description

Patented Feb. 10, 1953 ELECTROMAGNETIC AC'IUATOlP` Willis H. Gille, St. Paul, Minn., assigner to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a. corporation of Delaware Application March 27, 1950, Serial N o. 152,053

5 Claims. 1 This invention relates to an improved electromagnetic actuator and more particularly to an improved actuator of the polarized type. Polarized actuators as developed in the past have `possessed certain disadvantages in that they do not readily lend themselves to rotary type of output movement and require special apparatus such as springs or gravity sensing means to return the actuator to a neutral position with generally unstable results. Further, the prior art devices tend to be complex structures which failed to combine sensitivity of loperation with speed of response and sullicient output torque to satisfactorily perform controlling functions.

It is' therefore an object of this invention to provide an improved polarized actuator which is highly sensitive, with a rapid rate `of response yet having sufficient torque to perform desired controlling functions. Itis also an object of this invention to provide in a polarized actuator an arrangement which permits the polarizing winding to provide a magnetic or biasing action or effect. It is further an object of this invention to provide an improved polarized actuator which is simple in design and economical to manufacture.

These and other objects of this invention will become apparent as the following specification is read in the'light of Vthe accompanying drawings in which:

Figure l is a plan view of the improved polarized actuator,

Figure 2 is a side elevation view of the actuator of Figure 1 in section taken along the lines 2--2 of Figure 1,

Figure 3 is aplan view of the actuator with the end plates and rotor omitted,

Figure 4 is a side elevation view of the' structure of Figure 3 with the polarizing core members and windings omitted,

Figure 5 is a schematic view'of the actuator showing the controlling and polarizing windings thereon, and

Figure 64 isan exploded perspective view of the structure of Figure 4.

My improved polarized actuator, as shown in the drawings, includes a frame and pole assembly7 indicated at is 'having an aperture I I therein in which is positioned'a bar type rotor element of magnetic material I2. The frame and pole assembly IG is magnetized by means of polarizing core members indicated at I3 and controlling core members I4 which combine to vary the polarity of its pole shoes I5 and attract the rotor into a plurality of operating positions.

The pole and frame assembly IIJ, as best seen in Figures 3, 4 and 5, is generally of rectangular form being composed of four groups of laminations forming the pole shoes I5 which are held together in assembled relationship by solid nonmagnetic end plates I5 comprising the frame. The end plates and pole pieces are held in assembled relationship by any suitable means such as rivets Il and are so formed to provide the centrally located aperture I I wherein the rotor I2 is positioned.

Pole pieces or shoes I5 are generally L-shaped in form each having a curved surface indicated at Zil adjacent the aperture II designed to conform thereto. In this manner, they define in part the air gap in which rotor I2 is positioned and adapted to be rotated.

Although aperture II extends through the pole and frame assembly Iii, rotor I2 is constructed to have a width substantially equal to the stack of lamina-tions forming the pole shoes I5 and is designed to be positioned in the same plane therewith. Rotor I2 is of the bar type being rectangular in form and having curved outer eXtremities which are designed to conform with the curved surfaces 2t of the pole pieces I5 maintaining a minimum air gap therebetween. For purposes to be later noted, the rotor I2 is made of a magnetic material preferably of a soft iron, and is mounted on a shaft 2I by any suitable means such as press fitting. The shaft is journaled in a pair of end plates 22, 23 mounted on each end of the pole and frame assembly II) and covering Vthe aperture I in which the rotor is positioned.

Shaft EI is also made of a nonmagnetic material and is journaled in the end plates by suitable means not shown. End plates 22, 23 are attached to the frame and pole piece assembly by means of screws Z4.

The polarizing cores I3 of the actuator are mounted in abutting relationship against an end surface 25 of the L-shaped pole piece members I5 and are maintained in this position by means to be later described. The polarizing cores I3 are formed of laminated magnetic material barshaped in form and are held together by rivets Y indicated at 2t. Surrounding the polarizing cores formed by the lamina-tions are a pair of polarizing windings indicated at 2T which windings are adapted to be energized from a direct current source of power to magnetize the respective pole pieces I5 with opposite magnetic polarities. In assembled relationship, the polarizing cores I 3 fit against the end surface of the pole and frame assembly to which the surfaces 25 of pole pieces i5 are common and the windings 27 thereon t in part within the apertures formed by the end plate i6 and pole piece laminations I5 as can be seen in Figures 2 and 3. In this manner, a magnetic circuit is formed between the respective pole pieces I5 and the polarizing cores I3 such that the magnetic windings 21 may magnetize the pole pieces with a predetermined magnetic polarity. With the rotor positioned in the air gap or aperture I I in the frame and pole piece assembly, the pole pieces exert a magnetizing or attracting force upon the rotor I2 since the polarizing flux flows from the pole pieces through the tips or extremities of the rotor I2. The extent of rotor I2 is substantially free of this polarizing flux and hence does not approach a saturated condition. The windings 2 of polarizing core members are so connected to the D. C. source of power that diametrically opposed pole pieces will be magnetized from the polarizing cores I3' by opposite magnetic polarity as can be seen in Figure 5. In

this manner, the attraction of rotor I2 due to the magnetization of the pole pieces I5 from the polarizing cores I3 will be such that the rotor will be centrally located between the extremities of the pole piece members I5 being equally influenced by the respective pole pieces.

The controlling core members are positioned on the frame and pole piece assembly such as to contact a surface SII of the pole piece members in a direction normal to the contact between the polarizing core members and pole piece members I5. The controlling core members I4 are similarly made of stacks of laminated magnetic material held together by suitable means such as rivets 29. Each of the controlling core members mount a pair of control windings indicated at -3I, 32, and 33, 34. As can be seen in Figures l and 5, the controlling core members I4 are common to pairs of pole pieces I5 which have like polarities due to the magnetization of the polarizing core members I3 or which are not common to the same polarizing core member I3. Although the pairs of windings 3|, 32 and 3'3, 34 are each mounted on the same core respectively they are wound in opposition to one another such that current ilow through the windings 3I and 32 and 33 or 34 will reverse the respective magnetic polarities to be applied to the pole piece members I5. As can be seen in Figure 5, the windings 3i connected in series with winding 34 by conr ductor 44 and winding 32 is connected in series with winding 33' by conductor 45. The free ends of windings 3| 32 are connected together at a common point 46 which is adapted to be attached to the plus or positive side of the D. C. source of power. The free ends of windings 33, 34 are adapted to be connected to a pair of control devices 5G respectively, such as vacuum tubes which in turn are connected to a source of power, that is the grounded side of the D. C. supply to give selective and variable D. C. energization to the windings 3|, 34 or 32, 33. The tubes or control devices 53 form no part of this invention and are consequently shown schematically without controlling connections. It is to be understood, however, that the tubes 5I! are so connected and energized that only one will be conducting at a single instant with an output determined by its controlling circuit and therefore only one circuit through the windings 3'I, 34 or 32, 33 will be made at the same time. In this manner, the magnetic polarities cf the extremities of the controlling core members I4 will reverse and vary in magnitude depending upon which of the control devices 55 is operated and how it is energized. As

noted above the controlling core members I4 are held in abutting relationship with the frame and pole pieces of assembly lil at the surfaces 33 of the pole pieces I5 to thereby provide a magnetic circuit through the respective core members to the pole pieces I5, but fluX lines from the controlling core members must pass through the extent of rotor I2 to complete their magnetic circuit. These core members are similarly held in position against the respective pole piece members of the pole and frame assembly with portions of the windings thereon itting in apertures formed between the end plates and the pole pieces. It has -been found that a non-magnetic strap 52 inserted between the respective windings and the laminations of the core members and secured by a catch will satisfactorily hold the polarizing and controlling core members in an assembled relationship on the pole and frame assembly II), as can be seen in Figure l. However, any other suitable means may be used to maintain this relationship.

In operation, the subject polarized actuator differs from the prior art devices in that it has a Vneutral or rest position which is not fixed or determined through the aid of auxiliary spring devices or the like, Rotor I2 of the actuator is designed to rotate within the aperture II of the pole and frame assembly Ii) in a limited rotary type of movement. As shown schematically in Figure 5, the shaft 2l of rotor I2 is adapted to be connected to a variable load such as a cam 60 of a switching mechanism 6I whose contact blades 62 are operated as the rotor I2 and hence the cam 5G are rotated. My copending application Serial No. 180,626, dated August 2l, 1950, on Servo Systems, discloses the details of this variable load type switching device and its use with the subject actuator in a control system.

The polarizing core members I3 with the wind- S ings 27 thereon when energized from a D. C.

Y source of power magnetize the pole pieces I5 to attract the rotor I2 in an equal degree such that the rotor maintains a rest or no load position in which the rotor I2 is common to or adjacent to all of the pole pieces I5 and intermediate thereof. Since the rotor I2 is made of a magnetic material such as soft iron, it is attracted to and magnetized vby the magnetic polarities possessed by the pole pieces i5 and its extremities are traversed by this polarizing flux. The controlling core members I4 are so positioned to be common to pole pieces not common to the same polarizing cores and are designed to be selectively and variably magnetized by the windings 3l 34 or 32. 33 depending upon which of the controlling tubes 53 are conducting. In this manner the respective poles I 5 which have been magnetized by the polarizing core members I3 will have variable magnetic fields set up by the`controlling core members I4impressed thereon to add or detract from the existing polarity of the pole faces'ZIJ with the controlling iux lines traversing the extent of the rotor. However the rotor does not reach a saturated condition because only the controlling ux passes therethrough and hence is much more sensitive to a controlling signal. As can be seen in Figure 5, when the winding 3|, 34 are energized, one of the pole pieces I5 which is common to the north end of one of the polarizing core memberswill have a north pole added thereto while the opposite pole pieces I5 common to the same north polarity end of the other polarizing core will have a south polarity field added thereto. Similarly Ythe pole pieces I5 common to the south polarity ends of the polarizing core members |31'-willhave'impressed thereon due to the'energization ofV coil 34 .in-.north polarity and south polarity whichfwilltend to aid in the magnetization of one of the pole pieces and detract from the other. The'` core members and coils are so arranged that the pole pieces I5 in which the magnetic polaritiesadd are located in diametrically opposite relationship and vconsequently the pole pieces in whichtheelds of polarities subtract are also diametrically opposite from one another. In thismanner rotor I2 will be urged in a clockwise direction with a variable torque as seen in Figure 5 being attracted toward the polepieces I5 in which the fields from the controlling and polarizing core members add. With windings 32, 33 energized and windings 3I, 34 unenergized, rotor I2 will be rotated counterclockwise with a variable force toward the pole pieces I5 which are located diametrically opposite one another. With reference to Figure 5, the lower left hand pole piece will be magnetized with additive south polarity flux fields from the polarizing and controlling core members and the upper right hand pole piece will be magnetized with north polarity iiux field from the same respective pole pieces. Rotor I2 will therefore be attracted toward these respective pole pieces since they afford the greater attraction toward the rotor. By varying the degree of energization of the respective windings, the force with which the rotor will rotate in such aligned positions will be increased and similarly the speed of response is increased. It should also be noted that the polarizing eiect of the polarizing core members I3 upon the pole pieces I5 aids in the magnetization of the respective pole pieces thereby increasing the strength of the respective magnetic fields found in the pole pieces and the speed at which such fields is built up.

In considering this invention it should be kept l in mind that the present disclosure is intended to be illustrative only and the scope of the invention is to be determined only by the appended claims.

I claim as my invention:

l. In a device of the class described, in a magnetic frame member, a plurality of pole piece members of magnetic material mounted in said frame members each having curved pole faces to form a circular gap, a pair of polarizing core members with polarizing windings thereon each mounted to be common with a pair of said pole piece members, a pair of controlling core members each mounted to be common with a pair of said pole piece members not common to the same polarized core member, a pair of control windings each mounted in part on both of said controlling core members, and adapted to be selectively and independently energized with D. C. power, and a bar type rotor positioned within said air gap with its extremities located adjacent to the pole piece members common to the same polarizing core member.

2. In a device of the class described, a nonmagnetic frame member, four pole piece members mounted in said non-magnetic frame member each having curved pole faces to form a circular air gap, a pair of polarizing core members with polarizing windings thereon, each mounted to be common with a pair of said pole piece members, a pair of controlling core members each mounted to be common with a pair of said pole piece members not common to the same polarizing core member, and a pair of control windings each mounted in part on both of said controlling core members andV adapted tov be. selectively and` variably energized withVD. C. power, and a. rotor of magnetric material having salientv portions adjacent respectively to the pole piece members common to the same polarizing core member positioned within said air gap and adapted to be attracted between diametrically opposed pole pieces.

3. Ina'device of the lclass described, a nonmagnetic frame member, a plurality of pole piece members mounted thereon each having pole faces to forman opening therebetween, a pair of polarizing core members with polarizing windings thereon each mounted to be common witha pair of said pole piece members, said polarizing windings being adapted to be energized from the constant source of DIC. power, a pair of controlling core members each mounted to be common with a pair of said pole piece members not common to the same polarizing core member. a pair of control windings each mounted in part on both of said controlling core members and each adapted to be selectively and variably energized from a variable source of D. C. power, a rotor of magnetic material having salient portions adjacent respectively to the pole piece members common to the same polarizing core member and positioned within said opening, said pole piece members being magnetized differentially from said polarizing and control core members to rotate said rotor between a pair of limit positions deiined by diametrically opposed pole pieces, and nonmagnetic means encircling said polarizing and controlling core members and adapted to hold them in assembled relationship on said frame member.

4. In a device of the class described, a nonmagnetic frame member, a plurality of pairs of pole piece members of magnetic material mounted in said frame member and having pole faces disposed to form a circular air gap, a pair of magnetic members of Xed polarity each mounted on said frame member so as to cooperate with said pole piece members of one of said pairs and to cause the pole piece members of each pair to assume opposite magnetic polarities, a pair of controlling the core members each mounted to be common with a pair of said pole piece members not common to the same magnetic members, a pair of control windings mounted on each of said controlling core members, one winding of each pair on said controlling core members being connected to a winding of said pair on the other of said controlling core members, means for independently and selectively energizing said interconnecting windings on said controlling core members to selectively magnetize said controlling core members with different magnetic polarities, and a rotor of magnetic material positioned within said opening and having salient portions positioned adjacent respectively to the pole piece members common to the same magnetic member, said pole piece members being differentially magnetized by said magnetic and said controlling core members to rotate said rotor with a variable torque between a pair of limit positions dened by said diametrically opposed pole pieces of said pairs.

5. In a device of the class described, a nonmagnetic frame member, a plurality of pairs of pole piece members of magnetic material mounted in said frame member with pole faces disposed about a circular air gap, a pair of magnetic members of fixed polarity each mounted so as to cooperate with said pole piece members of one of said pairs and to cause the pole piece members 7 of each pair to assume opposite magnetic polarities, a pair of core members each extending between the pole piece members of like polarity of said pairs, a pair of control windings mounted on each of said core members, one winding of each pair on said core members being connected to a winding of said pair on the other of said core members, means for independently and selectively energizing said interconnected windings on said core members to selectively polarize said pole piece members with diierent magnetic polarities, and a rotor of magnetic material positioned within said circular air gap and having salient portions positioned adjacent respectively to the pole piece members common to the same magnetic member.

WILLIS H. GILLE.

8 REFERENCES CITED The following references are of record in the .le of this patent:

' UNITED STATES PATENTS Number Name Date 1,252,312 Warren Jan. 1, 1918 1,572,452 Thomas Feb. 9, 1926 1,784,517 Farrand Dec. 9, 1930 l U FOREIGN PATENTS Number Y YCountry Date 123,049 Switzerland Oct. 17, 1927

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