US2896100A - Electrodynamic machine - Google Patents

Description

July 21, 1959 J. S.-AXELSON ELECTRODYNAMIC MACHINE Filed Dec. 9, 1957 [ht/677:0)", Jahri Axe/$027, y %W./% m

. [791$ Attqr'wey.

United States Patent C) ELECTRODYNAMIC MACHINE John S. Axelson, Erie, Pa., assignor to General Electric Company, a corporation of New York Application December 9, 1957, Serial No. 701,532

4 Claims. (Cl. 310-51) are laid in slots provided in the armature core'and are held in place by wedges of wood or other suitable material. On larger machines, the windings and wedges are further held in place by overlying binding or retaining bands, the latter being provided at one or more places over the periphery of the central portion of the armature, as well as at the ends of the armature where the individual windings are connected together and to the commutator. The binding bands are required to prevent the wedges and individual windings from flying out of their slots under the influence of centrifugal force when the armature is rotating, as well as to keep the end portions of the windings and their connections in place under such conditions. For some time, metal bands or wires were employed to bind the windings in place in the armature core, and any dynamic balancing of the armature required was performed by rotating the armature in any of the well-known dynamic balancing devices, and applying metal solder or molten metal to the metal bind ing bands, preferably the end bands which are usually at reduced portions of the armature and are not critical in so far as clearance with the stator or other parts of the machine is concerned. The metal so applied was then adjusted and trimmed as required to achieve perfect dynamic balancing of the armature. While such metal binding bands serve their purpose, they are undesirable from some points of view. Extreme care must be taken during installation of such bands both to insure that they are tight enough and also to insure that they do not cut into the winding insulation, particularly at the end portions where they are laid directly over the windings. Any such metal binding bands that Work loose because of improper fitting or which because of sharp edges or for other reasons cut into the insulation, induce failure of the machine. The use of solder or other relatively low melting point metal on such metal bands as a balancing medium involves the removal of insulating varnish from the band, cleaning, and the application of flux. Furthermore, should the rotor overheat, such heat is quite readily and directly transmitted to the solder through the metal bands, causing early melting and subsequent failure of the machine.

An improvement in armature or rotating part binding bands was brought about when resin-impregnated tape or roving was introduced for this purpose, the tape being wound tightly around the armature under tension, and cured to form a unitary band, which was both easier to apply than metal and much less likely to cut into the insulation. Furthermore, as the tape was cured in place,

location on the band determined.

Patented July 21, 1959 varnish. Tape of glass fiber cloth of various weaves or of essentially parallel filament glass roving or tape are generally preferred for such binding bands, although when the stress conditions are not as stringent, other fabrics or fibers such as of paper, cellulose, asbestos, or parallel filament constructions, etc. can be used. However, despite the many advantages of resin-impregnated binding bands, there has been no convenient way of attaching to them a weighting material which would permit the ready balancing of armatures or rotating parts to which they are mounted since the conventional use of solder is not applicable to resin-impregnated bands. As a result, even where resin-impregnated binding bands are used, the end bands are normally still of metal and the balancing of the armature is accomplished by means of solder or similar metal applied to such metal bands.

A principal object of this invention is to provide ready means for balancing armatures or other rotating parts of electrodynamic machinery wherein resin-impregnated binding bands are employed.

Briefly, the invention comprises means for balancing rotatable members of electrodynamic machinery having resin-impregnated binding bands wherein a material comprising a metal-filled resin or one which is filled with other high density material and which is compatible with that of the resin in the binding band is employed. In balancing an armature or similar part in accordance with this invention, the part is simply placed in any well known balancing device, rotated, and the amount of balancing material necessary for balancing and its proper .Then the spot on the binding band where the balancing material is to be applied is cleaned, as with a solvent, and the proper amount of metal-filled resinous material applied thereto and cured in place.

- balancing material is readily accomplished by abrading it bonded tightly to the underlying resin of the insulating or scraping excess material from the main body of balancing material or, conversely, by adding more of the metal-filled material to the same or other spots on the binding band.

Those features of the invention which are believed to be novel are set forth with particularity in the claims appended hereto. The invention, along with its method of operation, will, however, be better understood from a consideration of the following description and the drawing, in which the single figure is a perspective view of an armature member illustrating the invention.

Any of the usual thermosetting resins can be used in conjunction with the invention so long as the resin used will adhere to the binding band and its impregnant. Dependent upon this condition, phenolic type resins can be used as can polyesters and silicone resins, as well as urea and melamine-formaldehyde type resins, among others. Those resins known as epoxide, ethoxyline or epoxy resins are particularly well adapted to the present use since they are compatible with most other resins and will adhere tenaciously thereto. Generally, such epoxy resins comprise a polyether derivative of a polyhydric organic compound, said derivative containing 1,2 epoxy groups, the compound being selected from the class consisting of polyhydric alcohols and phenols containing at least two phenolic hydroxy groups. For example, US. Patent 2,324,483 to Castan discloses epoxy resin compositions comprising the reaction product of phenols having at least two phenolic hydroxy groups and an epihalogenohydrin such as epichlorohydrin, the product having at least two epoxy groups and being cured to a thermoset, infusible mass by the use of a carboxylic or polybasis acid or acid anhydride such as phthalic anhydrides. Other acid type curing agents for epoxy resins include hexachloroendomethylenetetrahydrophthalic anhydride, maleic anhydride and pyromellitic dianhydride. The use of Any further adjustment 'of the organic nitrogen base or amine type materials to cure epoxy resins is also well known as set forth, for example, in Patent 2,444,333, such materials often giving a rapid cure at room temperature. The use of boron trifiugrideamine complex materials as epoxy resin curing agents is also well known as disclosed, for example, in Greenlee Patent 2,717,885. United States Patents 2,494,295; 2,500,600 and 2,511,913 describe further ethoxyline resins which can be used in conjunction with this invention and the above patents are all hereby incorporated by reference in this application.

The ethoxyline resins preferably used herein have more than one epoxy group per molecule. They can be prepared by reacting a polyhydroxy alcohol or phenol, such as hydroquinone, resorcinol, glycerin and condensation products of phenols with ketones, for example, bis- (4-hydroxy phenyl)-2,2-propane with epichlorohydrin. The reaction of epichlorohydrin with bis-(4-hydroxy phenyl) 2,2propane is as follows:

able. When cured, the putty is readily trimmed by filing or by other methods.

Example 2 To 80 parts of Epon 828 and parts of Epi-Rez 507 there were added 850 parts of powdered lead and about 5 parts of glass fibers having an average length of about inch, and parts pyromellitic dianhydride. The conconsistency of this material again was about that of a iers p t Shown in the drawing is armature 1 which is typical of the rotatable parts which can be dynamically balanced according to this invention. Mounted upon shaft 2 are laminations which make up armature core 3 having longitudinal slots 4 in which are mounted coils 5 held in place in the slot portions by wedges 6. Commutator 7 mounted toward one end of the shaft 2 serves as a curent coll tor. A u e p r phery of h m t co e prep r i m un ed at least e, and pr fe a ly, as

where n has an average value ranging from 0 to about 10. Such ethoxyline resins are sold under the name of Epon by Shell Chemical Corporation, under the name Araldite by the Ciba Company, as Epi-Rez resins by Devoe-Raynolds Company, and ERL resins by the Bakelite Company. The data given below for such resins is representative.

Any high density filler can be used in conjunction with the resinous material. Generally, a material such as lead is preferred because it will afford the greatest weight per unit volume and permit the use of smaller amounts of balancing material. However, it is to be understood that this does not preclude the use of other metals in connection with the present invention provided they do not melt at the operating temperature under the operating temperature of the device. Other high density materials can be used, such as red iron oxide, etc.

The following examples are illustrative of a composition which is useful in connection with the invention and are not to be taken as limiting. All parts are by weight.

Example 1 With 25 parts of Epon 828 there were mixed about 227 parts by weight of powdered lead resulting in a mixture having the consistency of glaziers putty. There were mixed with this material two parts of diethylenetriamine as a curing agent. The cure time for this resin is from about 1 to 3 minutes under an infrared heat lamp of the usual type. For example, a five hundred watt lamp held at a distance of 2 to 3 inches from the band is suitsuitable tool.

shown, a plurality of binding or retaining bands 8 which serve to retain wedges 6 and windings 5 in place in the core slots when the armature is rotating at high speeds. Additional binding bands are provided at the ends of the armature core where the windings 5 are drawn together for'interconnecting as at 9 and at 10 where they are attached to the commutator. As pointed out above, it has been found that resin impregnated fibrous material makes an economical band which is as strong as metal bands and does not have the disadvantages of; the latter.

In carrying out the invention, the armature, including the binding bands after assembly, is placed in a dynamic balancing machine of any well known type and rotated. When the point at amount of unbalance is determined, the surface of one or both ofthe end binding bands as indicated is cleaned and the filled resin with curing agent as described above applied thereto and more or less flattened out as shown in 11 or 12 with a spatula or other The resin is cured in any convenient mannor, for example, by placing an infrared lamp near the resin. The resin of Example 1 will cure to a hard thermoset state in about two minutes under such treatment and the resin of Example 2 takes about three minutes to cure under like conditions. Other means of curing may be used, such as oven treatment, etc.

'When the filled resin balancing weight has been cured, the armature is once again placed in the dynamic bal ancing apparatus and tested. If the weight added is too great, it may be readily trimmed down to proper weight as byfiling. More weight, if indicated, is added as above.

{Ilhere are provided by this invention means and methods for balancing the armatures or other rotating parts of electrodynamic or other machinery which utilize resin impregnated binding or retaining bands for retaining the rotating assembly in place against the action of centrifugal force. It will be realized, of course, that the present balancing means can also be used for metal bands as well as when the base is a material such as an epoxy resin, etc, which readily adheres to metal. The use of high temperature resistant resin, such as that of Example 2, using -a pyromellitic dianhydride cured epoxy resin, perrrritsthe operation of machinery at temperatures up to the order of about C. without disrupting the balance ofthe armature. In the practice of the present invention,

the resin acts as an insulation and retainer for the high density metal or other filler so that it does not melt even under the most stringent operating conditions in which the temperature might actually exceed the melting point of the filler.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A rotating member for an electrodynamic machine having at least one resin-impregnated band therearound, at least one of said bands having adherent thereto a resin material filled with a relatively high density filler.

2. A rotating member for an electrodynamic machine having at least one resin-impregnated binding band therearound, at least one such binding band having adherent thereto an epoxy resin filled with a relatively high density material for balancing purposes.

3. The process of dynamically balancing a rotating part for an electrodynamic machine, said part having at least one resin reinforced binding band, which process comprises applying to at least one such binding band a resin filled with a relatively high density material in such quantity and at such point which balances said rotating part.

4. The process of dynamically balancing a rotating member for an electrodynamic machine, said machine having at least one resin reinforced binding band, which process comprises applying to at least one such band an epoxy resin filled with a relatively high density material to balance said member.

References Cited in the file of this patent Glass Tape for Armature Banding, from Railway Locomotives and Cars, December 1957, pp. 38 and 39.

Images