US1578575A - Electromagnetic brake - Google Patents

Description

March 30 1925. 1,578,575

E- M. BOUTON ET AL ELECTROMAGNETIC BRAKE Filed Sept. 8,1919

I VENTOR Patented Mar. 30, 1926.

UNITED STATES PATENT OFFICE.

EDGAR M. BOUTON,-OF WILKINSIBURG, AND MILTON G. THOMPSON, OF ARDMOIR-E, BRADDOCK TOWNSHIP, ALLEGHENY COUNTY, PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTROMAGNETIC BRAKE.

Application filed September 8, 1919. Serial No. 322,316.

To all whom it may concern:

Be it known that we, EDGAR M. BoU'roN, a citizen of the United States, and a resident of l'Vilkinsburg, in the county-of Allegheny and State of Pennsylvania, and MILTON Gr. THOMPSON, a citizen of the United States, and a resident of Ardmore,

Braddock Township, in the county of Allegheny and State of Pennsylvania,l1ave invented a new and useful Improvement in Electromagnetic Brakes, of which the following is a specification.

Our invention relates to electromagnetic brakes and it has particular relation to such brakes as are operated in connection with alternating-current systems.

The object of our invention is to provide a brake of the character indicated above that shall be simple in construction and efficient in operation to prevent the noises and chattering that are usually incident to the operation of brakes of a similar character.

Brakes that are actuated by alternatingcurrent magnets possess the defect, to a greater or less degree, of producing noises that are caused by the vibration or chattering of the movable armature with respect to the ends of the pole facesof the stationary core member. This condition results from the variation in. the forces applied to the armature by reason of the alternations of the electric current and the consequent increase and decrease in the pulls of the re spective pole pieces.

' Various devices have been suggested heretofore for remedying the condition de' scribed above, such, for example, as secondary coilsor shading coils that assist in maintaining the pulls of the several pole pieces more nearly constant. Such coils have modified the unsatisfactory conditions obtaining in connection with the operation of alternating-current magnets. but it has been found that electromagnets constructed under apparently identical conditions have produced widely varying results in practice. Investigation has proved that it is impossible to manufacture pole faces for armatures in such manner that the armatures will always be properly seated when brought into engagement with the faces of the pole pieces. The chattering of such magnets increases with the degree'of improper seating of the armature upon the pole pieces, notwithstanding the use of shading coils and other devices tending to. insure quiet operation of the magnets.

Our invention provides an arrangement whereby the armature is permitted to adjust itself to the faces of the pole pieces in such manner that it is always properly seated upon them. It has beenfound, in practice, that the engagement of substantially the entire faces of the coacting parts insures operation of a morenearly quiet character than is possible with any of the arrangements proposed heretofore. In order to permit the adjustment of the engaging parts, we secure the armature of the magnet to the lever arm of the brake by means of bolts and springs which tend to maintain these parts in fixed relation but permit of relative movements in order that the armature may adjust itself to the faces of the pole pieces in the manner described above.

In the accompanying drawings, Fig. 1 is a sideview, in elevation, of a portion of the frameof an electric motor and an elec tromagnet secured thereto; and Fig. 2 is a view, similar to that of Fig. 1, but taken at right angles thereto.

A frame 1, which may be that of a friction brake, an electric motor or other suitable machine, supports an electromagnetQ.

The electromagnet consists of a laminated.

core structure 3 and magnetizing coils 4: which may be connected in any suitable manner (not shown) with a source of alternating current. An armature member 5 of magnetizable material is yieldingly secured to a lever 6, only a portion ofwhich is shown, by bolts 7 and springs 8. The lever arm 6 may be, for example, that of a brake for controlling the rotatable part of an electric motor or similar part of any machine. The pole pieces of the magnetizable core member 3 are provided with the usual and well-known shading coils 9.

Referring particularly to Fig. 2, it will be noted that the bolts 7 have a rigid connection with the armature 5. Sufficient clearance is, however provided in the holes 10 in the lever arm 6 to ensure-that relative movement may occur under conditions to be later described. The springs 8 are positioned between the arm 6 and the heads of the bolts 7 and tend to maintain the engagement of the armature 5 with the arm 6. The forces exerted by the springs for this purpose may be varied by adjusting the bolts 7 to correspondingly vary the degree of compression of the springs. The bolts 7 are maintained in their adjusted position by suitable cotter pins 11.

It may be assumed, that the magnet is in its open position to release the lever 6. Upon the closing of the circuit of the coils 4 in any usual or well-known manner, the core 3 is energized to draw the armature 5 and the lever 6 to their respective positions illustrated in Fig. 2. In case the faces of the pole pieces of the core member 3 are exactly parallel to the face of the armature 5, the coacting surfaces of these parts will be in engagement and no relative movement of the armature 5 with respect to the lever 6 will occur. 7

If, however, due to imperfect construction and assembling of the several parts or for other reasons, the coacting surfaces do not engage each other properly, the springs 8 permit movement of the armature 5 relatively to the lever 6 until the armature is properly seated upon the pole faces. The magnet then operates quietly 1f the proper adjustments have been made.

If, however, the tensions of the several springs are not such that the freedom of movement of the armature member is adapted to the characteristics of the magnet employed and the latter is noisy in operation, the cotter pinsll are removed, the nuts 7 are adjusted until the chattering is reduced to a minimum and the cotter pins are then replaced to lock the nuts 7 in their respective adjusted positions.

Our invention provides a simple and effective means for insuring the quiet operation of electromagnets of the alternatingcurrent type, regardless of imperfections and lack of uniformity in the manufacture and assembling of the various parts. The perfect seating of the armature upon the pole faces is secured at all times, and the satisfactory operation of the device is not affected by the disturbance of the adjustment of the relatively movable parts incident to wear.

N e claim as our invention:

1. The combination with a magnet having substantially plane pole faces and a magnetizable member actuated thereby and having substantially plane portions for coactingwith said pole faces, of a supporting element fors'aid member yieldingly secured thereto whereby limited universal movement of saidmagnetizable member is permitted.

2. The combination with a magnet and a magnetizable member actuated thereby said magnet and said member having relatively movable engaging surfaces, of a movable element, and means for yieldingly securing said element to said member to permit relative adjustment of said surfaces.

3. The combination with a' pair of coacting magnetizable members having substantially plane engaging surfaces and means for energizing one of said members, of a movable element for supporting the other of said members, and means for yieldingly securing said movable element to said other member to permit relative adjustment of said surfaces upon the engagement of said members.

4. The combination with a pair of coacting magnetizable members having relatively movable engaging portions and means for energizing one of said members, of an element for supporting one of said members and yielding means for securing said sup ported member to said element for movement relatively thereto'to permit conformation of said engaging portions.

5. The combination with a pair of relatively movable magnetizable members having coacting surfaces of a movable element for supporting one of said members, and

means comprising a spring for securing said element to said one member but permitting movement relatively thereto for insuring parallelism of said surfaces upon the engagement of said members.

6. The combination With a pair of mag netizable members, one of which is movable into and out of engagement with the other, of means for insuring the seating of said movable member when in engagement with the other, said means comprising a supporting member for said movable member yieldingly connected thereto.

7. The combination with a stationary core member and'a movabl'e'armature member, of'yielding means for supporting said armature member and for permitting said movable member to adjust its position to that of said stationary member When said members are in engagement.

8. The combination with a stationary core member, means for energizing said member,

and a movable armature member having a' surface for engaging a corresponding surface of said core member, of a member for supporting said movable member, and means comprising a resilient element for connecting said movable member to said supporting member, but permitting the relative adjustment of said engaging surfaces.

9. The combination with a stationary core member, means for energizing said member, and a movable armature member having a portion for engaging the core member, of a member for supporting said movable memher, and means comprising a plurality of springs for connecting said movable mem her to said supporting member and for yieldingly maintaining the relative positions of the connected members.

10. The combination with a stationary core member, means for energizing said member, and a movable armature member, of a member for supporting said armature member, means comprising a plurality of springs symmetrically disposed with respect to said armature member for connecting said armature member to said supporting member, and for yieldingly maintaining the relative positions of the connected members,

and means for adjusting the tension of said springs.

11. The combination with a stationary core member and a magnetizable member, said members having coacting engaging portions, of means comprising a secondary coil for magnetizing said core member, and means comprising a movable member for yieldingly and movably supporting said magnetizable member to permit limited universal movement thereof relatively to said movable member.

12. The method of preventing the chattering of alternating-current magnets which consists in resiliently supporting the armature member, adjusting the armature member to such degree of yielding as to stop the chattering and then looking the adjusting means. i a

18. In an alternating-current magnet, a core member having a pole-face, an armature member, supporting means for the respective members and a Winding for drawing the armature member against the poleface, one of the members being biased to one position on its supporting means but yieldable relatively thereto so that the pole-face and armature mayautomatically come into parallelism with each other upon engagement of the armature with the pole-face, and

means for l1m1t1ng the movement of one of the members.

14- The method of preventing the armature and core members of alternating-current'electromagnets from chattering which consists in biasing onerof the members to one position on its supporting means, adjusting said member to such freedom of movement as to stop the chattering and then limitingthe adjusted member to such freedom of movement.

15. The combination with a stationary core member having substantially plane pole faces and an energizing coil therefor, of an armature member for coacting with said pole faces, a movable member for carrying said armature member and means comprising a plurality of adjustable members and a corresponding number of springs for con necting said armature member to said movable member for limited universal movement relatively thereto whereby said armature member may conform to the plane of said pole faces.

In testimony whereof, we have hereunto subscribed our names this 30th day of Aug,

I EDGAR M. BOUTON.

MILTON Gr. THOMPSON.

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