US2061821A - Commutator - Google Patents

Description

NOV. 24, 1936. V. G APPLE 2,061,821

COMMUTATOR V. G. APPLE COMMUTATOR Filed April 27, 1935 2 Sheets-Sheet 2 Nov. 24, 1936.

Patented Nov. 24, 1936 UNITED STATES- 24,061,821 COMMUTATOB.

Vincent G. Apple, deceased, late of Dayton, Ohio, by Gourley Dan-och, executor, Dayton, Ohio Application April 27, 1935, Serial N0. 18,528

10 Claims. (VCL 171-321) This invention relates to commutators and an improved process for making them, and particularly to commutators of the molded type.

Molded commutators in very small sizes have met with considerable commercial success, and

these for the most part have been made by imbedding the metal segments in a core of molding compound, usually comprising synthetic resin.

But for the larger sizes of commutators the molding process has come into disfavor, one rea'- son being that the volume of the insulating compound necessary to make a commutator core, as molded commutators have heretofore been made, is considerable, as compared with thevolume of mica in the older type commutator Where there is a metal core with just enough sheet mica between metal parts to properly insulate them.

Another and perhaps the greatest factor which hinders the success of the molded commutator of large size as at present made. is that cores of the commercial molding compounds used are not stable, but change in size and shape from the continued heating and cooling to which commutators are subjected, and this instability becomes more pronounced and objectionable as the volume of material in the core is larger.

It is therefore the object of this invention to make a better commutator at less cost than may be made from the materials and by the methods at present employed, by using an insulating core material which is more stable under temperature variation than the materials now used for commutator cores, and by using it in as small a volume and in as thin sections as may be practicably molded and as will sufciently insulate the several parts.

This. object is attained in the structure, with the materials, and by the process hereinafter described and illustrated in the drawings wherein,

Fig. 1 is a transverse section, taken at I-I of Fig. 2, through a mold which I employ in my process.

Fig. 2 is an axial section through the same mold taken at 2-2 of Fig. 1.

Fig. 3 is a transverse section, taken at 3-3 of Fig. 4, through a second mold used in my process.

Fig 4 is an axial section through thej second mold taken at 4--4 of Fig. 3.

Fig. 5 is a side view of one of the commutator segments.

Fig. 6 is an end view of the commutator segment Fig. 5. f

Fig. 'I is an axial section through one .of the reinforcing members.

Fig. 8 is an end view of the reinforcing member Fig. 7.

Fig. 9 is an end viewof a second reinforcing member.

Fig. 10 is an axial section through the reinforcing member Fig. 9.

Similar numerals refer to throughout the several views.

In lcarrying out this invention the mold II, Figs. 1 and 2, is first provided. In mold II the base I2 is reduced in diameter at the upper end to receive the operating ring I3 which is rotatable thereon. Operating ring I3 has bevel gear teeth I4 on its lower side and a scroll I6 on its upper side. A key wrench I'I has a bevel pinion I8 on its inner end and rotation of the key wrench similar parts turns the operating ring.

A mold ring I9 is secured to the top of the base I2 by screws 2l. Mold ring I9 has a plurality of radial slots in its lower side. The radially movable jaws 22 are slidably iltted to these slots. There are scroll teeth 23 in the lower edges of the jaws which extend into the scroll I6 on the upper surface of the operating ring I3, whereby rotation of the operating ring I3 by the key wrench I1 simultaneously moves all of the jaws 22 in a radial direction.

Jaws 22 have spacing tangs 24 at their inner ends. The spaces between circumferentially adjacent tangs 24 comprise a series of keystone shaped pockets for receiving the metal commutator segments 26, shown separately in Figs. 5 and 6. Movement of the jaws 22 radially inward decreases the size of these pockets, While moving them radially outward increases them.

A stock ring 2'I rests on the upper side of the mold ring I9 and a plunger 28 is vertically slidable therein. An ejector plug 29 is slidable in the base I2 and a center stud 3| is slidable in the plug 29.

In order that the commutator may be required to depend as little as possible for its resistance to centrifugal force upon the insulation used in the core, the special metal reinforcing sleeves 32 and 33, Figs. 'l to 10, are provided. Sleeve 32 fits closely over the sleeve 33, and they are flanged at 34 and 36 respectively. Flanges 34 and 36 are perforated as at 31 and 38 while the sleeves 32 and 33 have radial perforations 39 and 4I respectively. When the sleeve 32 is in place in the commutator over the sleeve 33, the radial perforations 39 and 4I are in alignment. The operation of mold II is as followsz I'he stock ring 21 is removed from the mold and a sleeve 33 is placed over the stud 3| with the flange 36 downward. The key l1 is'then turned until the pockets between the spacing tangs 24 are large enough to flt the segments 26 freely. A set of segments is then placed in the pockets and the key Il is turned until the segments are all gripped firmly in the pockets between adjacent spacing tangs 24. A sleeve 32 is' then pressed downward over the sleeve 32 with the perforations 39 and 4I in alignment. is now put into place on the mold, the proper amount of insulating compound put into the ring, the plunger 26 inserted and pressed home as shown in Fig. 2 with a pressure of several tonsI per square inch.

The nature ofthe insulating compound employed in the process may differ materially from the compounds commonly used for this purpose. For example a suitable compound may comprise a flller of powdered mica and/or powdered asbestos and/or other powdered silicates, with a flux comprising lead salts, lead borates, boro silicates or kindred materials, the dry ingredients being mixed with sufllcient liquid to make a somewhat plastic paste.

With the heavy pressure still on the mold, heat is applied in such degree as will expel the liquid froml the compound, after which the stock ring 21 and the plunger 26 are laid aside, the key I'l turned to withdraw the spacing tangs 24 from between the segments 26, the ejector plug 29 forced upwardly, and the commutator pressed from the mold.

Where an undercut commutator is desired, no further molding operation is necessary, but inasmuch as there are many instances where an undercut commutator is unsuitable, the further operation of filling the open spaces left by the withdrawal of the spacing tangs 24 from between the segments 26 is shown. To this end the commutator is placed in the mold 42, Figs. 3 and 4, and a second molding operation performed to fill these spaces.

Mold 42 comprises a body 43, a stock ring 44, a plunger 46, an ejector plug 41 and a center stud 48. The commutator, as it comes from the mold Ii, is placed in the mold 42, a small volume of the molding compound placed under the plunger 46 and forced home by heavy pressure as in the first molding operation.

The 'insulating compound used in the second molding operation may be the same as that used in the first, or it may differ somewhat. For instance, the arc resisting Aproperty of the insulation at the outer surface of the commutator where brush arcing sometimes takes place may be increased by taking a compound such as is used in the first molding operation and modifying it by adding a small percentage of zirconium oxide and using this for the second molding operation.

While the mold 42 is held closed by heavy pressure, heat is again applied to dry the molding compound after which the commutator is removed from the mold and red in a separate furnace at a temperature of about 1400 degrees Fahrenheit for a length of time sufficient to vitrify the compound, this length of time varying of course with the size of the commutator being made. At 1400 F. the metal parts are sufciently plastic to cause the vitreous material and the metal to fuse together so as to be afterwards inseparable, and to this end the metal parts may comprise alloys or undergo surface treatments as in common practice in applying vitreous enamels to metal surfaces.

It will be seen that a nished commutator made The stock ring 21` as hereinbefore described is capable of withstanding a high degree of heat because of the nature of the insulation used. It is capable of withstanding high speed because it does not depend on the insulation but on the metal parts of the core to bind it together. And it will not readily distort, because the vitreous core material is more permanent than materials commonly used for this purpose and because the insulation is applied in thin sections between layers of metal.

It will be noticed that the metal ange I6, Fig. i0 projects from the insulation as at 49, Fig. 4 to form an end-thrust bearing for the commutator when it is in operation. At the opposite end a short hub 5| of insulation is formed to keep separate the metal parts of the commutator from a winding to which it will be adjacent in operation.

Having described the invention what is claimed 1. In a commutator, a cylinder of circumferentially spaced apart metal segments, and a continuous layer of vitreous insulation extending around the inside of the cylinder and between the segments, said insulation and metal segments being fused together at their contacting to the surfaces.

2. In a commutator, a cylinder of circumferentially spaced apart metal segments, a metal reinforcing member overlying portions of said segments, and a continuous layer of vitreous insulation extending between the several segments, and between said segments and said reinforcing member, said insulation being fused to said segments and to said reinforcing member where it comes in contact therewith.

3. A commutator comprising a plurality of circumferentially spaced apart metal segments imbedded in a core of vitreous insulation comprising a filler of powdered silicates dispersed in a metallic flux compressed between and about the segments and vitrifled in situ. the insulation and the metal parts being fused together where they ioin.

4. In a commutator, a cylindrical row of circumferentially spaced apart metal segments having a continuous layer of vitreous insulation comprising powdered silicates dispersed in a flux containing the oxides of lead compressed between and about the segments and vitrifled and fused thereto.

5. In a commutator, a plurality of metal segments in cylindrical formation, an annular metal reinforcing member having a part overlying end portions of said segments, and a layer of compressed powdered silicates dispersed in a flux containing the oxides of boron within the spaces between the several segments and the space between the segments and the reinforcing member fused to the surfaces of said segments and said reinforcing member.

6. A commutator comprising a plurality of circumferentially spaced apart metal segments imbedded in a core of vitreous insulation comprising mica dust dispersed in a ux containing the oxides of lead tightly compacted between and about the said segments fused thereto and vitrifled in situ.

'7. In a commutator, a metal cylinder comprising a plurality of spaced apart segments, and a single mass of vitreous insulation comprising mica dust dispersed in lead borate extending in a compact layer around the inner portions of the cylinder and between the segments, said mass being fused to said cylinder.

8. In a commutator, a cylinder composed ot metal segments with spaces therebetween a reinforcing sleeve having the end anged over axially extending parts oi said segments leaving space between the segments and the sleeve, and a layer of mica dust dispersed in lead borate compressed into the said spaces, vitried in situ, and fused to the surfaces of the metal parts.

9. In a commutatox, a metal cylinder comprising a series of circumferentially spaced apart segments imbedded and held in a core of vitreous insulation comprising a iler of powdered mica and powdered asbestos dispersed in a ilux containing the oxides of lead, said core extending in a closely compressed state between the metal segments and being vitried in situ.

10. In a commutator, a plurality of separated metal parts imbedded in and fused to a compressed mass of vitreous insulation comprising a iller of powdered mica and powdered asbestos dispersed in a flux containing the oxides of lead and boron.

GOURLEY DARROCH. Ezecutor of Vincent G. Apple, deceased;

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