US2408210A - Commutator construction - Google Patents

Description

A. E=AEDDLEE5N ET AL COMMUTATOR CONSTRUCTI ON Filed Feb. 27, 1945 INVENTORS ATTORNEY WH'NESSES:

Patented Sept. 24, 1946 COMMUT-ATOR CONSTRUCTIQN' FredA; Heddleson and Andrew C. Weieri'ch, Lima,

Ohio; assignors t Westinghouse ElectricCorporatiomEast Pittsburgh, Par, a.corpcration...of,f

Pennsylvania Application February 27, 1945, Serial No. 579,972

(Cl. El -320') 61 Claims. 1.

The present' invention relates to oommutators and; more particularly, to-a double commutator construction for multi commutator dynamm electric machines There are certain types of dynamo-electric machines, such: as dynamotors; which have two or more commutators, connected to different windings on the armature. Inthe usual construction of'these machines, the individual com" mutators aremounted on the shaft, and where it is necessary to have two commutators on the same side of the armature; as in the case of machines with a total of three or more cornmutators; the two commutators on one side of the armature have been placed side by side on the shaft. With this arrangement, the problem of carrying the leads from the armature winding to the outsidecommutatoris quite difiicult. The most usual practiceis to'mount the inside commutator on a spider which has axial openings through it, and to threadthe leads for the outside commutator through these openings; This is a relatively difficult and time-consuming operation and is, therefore, undesirable. Furthermore, placing two commutators side by side on the shaft makes the machine undesirably long for many applications; 7

The principal object of the present invention isto provide a construction in which two com mutators' are mounted together on the shaft of a dynamo-electric machine in such a manner that the leads can readily be connected to both commutators.

Another object of the invention is to, provide a double commutator construction in which two commutators are combined into a single assembly of smaller size and lighter Weight than two separate commutators.

A more specific object of theinvention is to provide a double commutator construction in which one commutator is mounted on the shaft and a second commutator surrounds and is mounted on the first commutator so that the leads can be connected to both commutators with equal facility and a simple and compact arrangement is provided.

Other objects and advantages of the invention will be apparent from the following detailed description, taken in connection With the accompanying drawing, in which:

Figure 1 is a side elevation, partly in longitudinal section, of a double commutator embodying the invention;

Fig. 2 is a fragmentary end viewof the double commutator of Fig. 1;

- in desired manner;

V"-groove' 3 formed in it at one end. The lower or inner commutator consists'of a plurality of' Fig; Sis a' partial'longitudinal seetionalview-of a dynamo-electric machine with'asightlymodi fiedformof'doublecommutator;

Fig: i isa longitudinal sectional view showing a modified embodiment-oftheinvention;

Fig; 5- is aview similarto Fig. 4: showing afurther'modification; and

Fig.- 6 is a fragmentary end viewof the commutator of Fig-.- 5;

Fig. 1 shows a double commutator assembly mounted on the shaft lof a dynamo-electric machine; shaft l by means cf-asleeveor bushing 2-, which may be pressedcn the-shaft or securedto the shaft commutator bars 4 which are-assembled to form acommutator cylinder the bars 4 being: wedgeshaped in cross section to forma cylindrical as sembly, and'being insulated from each other by mica orother suitable insulation the usual:

manner. The bars 4 are shaped at one end to engage in the -groove 3- of thebushingZ, and the bars haveV-grooves 5. at the other end. A V-ring Eengages-in the-V-grooves 5 of the commutatorbars 4, and the bars are insulated: from the'bu-shing- 2 and ring 6 by means of EtLShSQt of:

mica" 1', or other; suitable insulating. material.

The V-ring 6 ;may. be, retained in place by. rollingor: peening over azportionof the end ofsthe bushing 2, asindlcatedi at 8, or in any other suitable manner,. to clamp the. commutator bars 4 into in their upper surface for securing; the upperor outercommutator cylinder in place.

The outer commutator cylinder consists of a plurality of commutator bars; H! which are assembled into a cylinder in the usual manner the bars being insulated from each other by. mica insulation. The bars l2 have straight upper edges which form a cylindrical brush engaging surface l3.

V-grooves I 5 formed: in their lower portions and; the bars are retained in assembled position; and

The commutator is mounted on the- The-bushing 2 has a As shownv in- Fig. l, the bars :i, also have a pair of opposing V-grooves i 5 formed Each of: the bars, !2 a neck or riser 14 at one. end for connection of the leads, from the armature Winding; The bars 12- have,

secured to the bars" 9 of the lower commutator by means of a retaining ring member It. The ring I6, which may be made of steel, is formed with V-ring portions l1 and I8 at one side which are adapted to engage in the V-grooves l and II, respectively. V-rings l9 and are placed at the other end of the assembly engaging in the V-grooves H and H5 at the other ends of the commutator bars, and the rings l9 and 20 are held in position to clamp the bars in place in any suitable manner, as by rolling over or peening over portions 2| of the retaining ring H3. The ring I6 is insulated from the commutator bars by mica V-rings 22. Thus a simple and compact double commutator assembly is provided with an inner commutator mounted on the shaft and an outer commutator surrounding and mounted on the inner commutator.

In the assembly shown in Fig. 1, there is one cylindrical brush-engaging surface and one radial brush-engaging surface. Thus, the brushes for engagement with the outer commutator would be disposed radially while those which engage the inner commutator should be disposed axially. In most cases, however, space limitations would make it impossible, or at least undesirable, to arrange the brushes for the inner commutator axially, and they would have to be disposed at an angle to the shaft. This would give a larger area of contact for the brushes but might involve diiliculties in maintaining proper brush contact pressure throughout the life of the brush, and in obtaining good commutation.

A modified form of the invention which overcomes this difficulty is shown in Fig. 3 mounted in position in a typical multi-commutator dynamo-electric machine, such as a dynamotor. The machine shown in Fig. 3 has a shaft on which is mounted a rotor or armature member 26 provided with suitable windings 21. The stator member includes a frame 28 on which are mounted field poles 29 with field windings 30. The end of the frame 28 is closed by an end bracket 3| in which is mounted a bearin 32 for the shaft 25. The double commutator is mounted on the shaft 25 within the end bracket 3| and is shown as being identical with the commutator shown in Fig. 1 except that the bars 4 of the inner commutator are extended beyond the outer commutator at the side opposite the armature, and are shaped to provide a brush-engaging surface 33 at an angle to the shaft. Thus, brush holders 35 for the brushes 35 which engage the inner commutator can be mounted in the end bracket 3| at an angle to the shaft, and a considerable saving in space is effected over what would be required if the brush holders 35 had to be mounted axially. Radially disposed brush holders 31 for brushes 38 are mounted in the .end bracket 3| in position for the brushes 38 to engage the cylindrical surface of the outer commutator. The end of the machine may be enclosed by a cover 39.

Figs. 4, 5 and 6 show a further modification of the invention which provides a double commutator of minimum size and great simplicity. In this construction, as shown for example in Figs. 5 and 6, the lower commutator is mounted on a shaft 40 by means of a bushing or sleeve 4|. The bushing 4| may be similar to the bushing 2 previously described, and the commutator bars 42 of the lower commutator have V-grooves engaged by a V-rin formed on the bushing-4| and by a retaining ring 43 in the same manner as described in connection with Fig. 1. The bars 42 are insulated from the bushin 4| and retaining ring 43 by mica insulation 44. In this embodiment of the invention, the commutator bars 42 have a single V-groove 45 in their upper periphery. The bars 46 of the outer commutator may have the same shape as the bars I 2 previously described, and the V-grooves at one end of the bars 46 engage in the V-grooves 45 of the lower commutator bars 42, as clearly shown in Fig. 5, the bars being separated from each other by mica insulation 41. The bars 46 are clamped in position by means of a clamping ring 48 which fits in the V-grooves at the opposite end of the bars 46 to clamp them into the grooves 45. The rings 48 are insulated from the lower bars 42 by mica insulation 49 and may be retained in position in an suitable manner. As shown in Figs. 4 and 5, one simple and convenient manner of clamping the rings 48 in place consists in initially forming the bars 42 with a bifurcated end. The lower fork 50 extends out for connecting the armature leads to the commutator bar, while the other fork 5| of the bifurcated end is rolled over or peened over to engage the mica insulation 49 and clamping ring 48 to clamp the ring in place. After completion of this operation, a, saw may be passed radially between the rolled over portions 5| of the bars 42 to prevent short-circuits.

In this embodiment of the invention, the brushengaging surface 52 of the lower commutator may be disposed at an angle to the shaft 40, as shown in Fig. 5, for use with an angularly inclined brush holder in a manner similar to the assembly of Fig. 3, or, if desired, the bars 42 may have a rectangular shape and may be extended beyond the upper commutator so as to provide a cylindrical brush-engaging surface 53, as shown in Fig. 4, the construction shown in Fig. 4 being otherwise the same as that of Figs. 5 and 6. It will be understood, of course, that a cylindrical surface might be provided in the same manner on the lower commutator when a retaining ring is used between the commutator cylinders as in Figs. 1 and 3.

It should now be apparent that a double commutator construction has been provided in which by side, and thus makes possible a shorter machine. The double commutator is also lighter than two separate commutators, so that by using this construction a smaller and lighter dynamotor or other machine is made possible. This is an important consideration in the case of aircraft equipment, which is one of the important applications for machines of this kind.

The modified construction of Figs. 4, 5 and 6 has the same advantages as the construction of Figs. 1 to 3, with the additional advantage of being smaller in diameter and of simpler construction. This modification, however, has less mechanical strength and rigidity than the form of the invention shown in Figs. 1 and 3, but is very desirable in cases where the necessary strength can be obtained with this construction.

Certain preferred embodiments of the invention have been shown and described for the purpOSe of illustration, but it will be apparent that the invention is capable of various modifications and other embodiments, and it is not restricted to the particular details of construction shown. It is to be understood, therefore, that the invention includes all equivalent modifications and embodiments which come within the scope of the appended claims.

We claim as our invention:

1. A double commutator assembly for mounting on the shaft of a dynamo-electric machine, said assembly comprising a plurality of cornmutator bars disposed in a first commutator cylinder, means for holding said bars in assembled relation and for mounting said commutator cylinder on a shaft, said first commutator cylinder having a V-groove in peripheral surface, a plurality of commutator bars disposed in a second commutator cylinder surrounding said first commutator cylinder, said second commutator cylinder being secured to the first commutator cylinder by means of said V-groove.

2. A double commutator assembly for mount ing on the shaft of a dynamo-electric machine, said assembly comprising a plurality of commutator bars disposed in a first commutator cylinder, means for holding said bars in assembled relation and for mounting said commutator cylinder on a shaft, said first commutator cylinder having a v-groo-ve in its peripheral surface and having a brush-engaging surface at one side of said V- groove, a plurality of commutator bars disposed in a second commutator cylinder surrounding said first commutator cylinder, said second commutator cylinder being secured to the first commutator cylinder by means of said v groove.

3. A double commutator assembly for mounting on the shaft of a dynamo-electric machine, said assembly comprising a plurality of commutator bars disposed in a first commutator cylinder, means for holding said bars in assembled relation and for mounting said commutator cylinder on a shaft, said first commutator cylinder having a V-groove in its peripheral surface, a plurality of commutator bars disposed in a second commutator cylinder surrounding said first commutator cylinder, and means engaging said second commutator cylinder to hold the bars thereof in assembled relation, said means also engaging the V-groove of the first commutator cylinder to secure the second commutator cylinder thereto.

4. A double commutator assembly for mounting on the shaft of a dynamo-electric machine, said assembly comprising a plurality of commutator bars disposed in a first commutator cylinder, means for holding said bars in assembled relation and for mounting said commutator cylinder on a shaft, said first commutator cylinder having opposed V-grooves in its peripheral surface and having a brush-engaging surface at one side of one of said V-grooves, a plurality of commutator bars disposed in a second commutator cylinder surrounding said first commutator cylinder, and retaining means engaging said V-grooyes and also engaging said second commutator cylinder to hold the bars thereof in assembled relation.

5. A double commutator assembly for mounting on the shaft of a dynamo-electric machine, said assembly comprising a plurality of commutator bars disposed in a first commutator cylinder, means for holding said bars in assembled relation and for mounting said commutator cylinder on a shaft, said first commutator cylinder having a V-groove in its peripheral surface, a plurality of commutator bars disposed in a second commutator cylinder surrounding said first commutator cylinder, the bars of said second commutator cylinder having a V-groove therein adapted to be engaged in the .l-groove of the first commutator cylinder, means for retaining the second commutator cylinder in engaging relation with the V-groove of the first commutator cylinder, and means for insulating the two commutator cylinders from each other.

6. A double commutator assembly for mounting on the shaft of a dynamo-electric machine, said assembly comprising a plurality of commutator bars disposed in a first commutator cylinder, means for holding said bars in assembled relation and for mounting said commutator cylinder on a shaft, said first commutator cylinder having a V-groove in its peripheral surface, and having a brush-engaging surface at one side of said V-groove, a plurality of commutator bars disposed in a second commutator cylinder surrounding said first commutator cylinder, the bars of said second commutator cylinder having a V-gro-ove therein adapted to be engaged in the V-groove of the first commutator cylinder, means for retaining the second commutator cylinder in engaging relation with the V-groove of the first commutator cylinder, and means for insulating the two commutator cylinders from each other.

FRED A. HEDDLESON.

ANDREW C. WEIERICH.

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