US2205688A - Electromagnetic transmission - Google Patents

Description

June 25, 1940. y J. ELwx-:LL

ELECTROMAGNETIC TRANSMISSION Filed Aug. 26, 1957 OL H M m Nm El my Patented June 25, 1940 UNITED STATES PATENT OFFICE ELECTROMAGNETIC TRANSlWISSION Application August 26, 1937, Serial No. 161,086 In France September 7, 1936 11 Claims.

The present invention relates to a revolving mechanism comprising consumers of electric current, more particularly to lubricated gears having rotating electromagnets, whereby the current is transmitted to said consumers or electromagnets by means of a slip ring and a brush sliding thereon.

When using customary carbon brushes having a rotund or rectangular cross sectional congurav tion, the lubricating oil which cannot be prevented from. reaching the slip ring forms a thin film between the ring and the brush and increases the electric transition resistance considerably. This resistance should be as low as posll sible because, for example in the case of electric motors, the voltage of the exciting current is relatively low. For example in the case of the starter motor in a motor car, the current is supplied by a battery and naturally not much tenl sion is available to overcome high resistances. If the slip ring is protected against oil and held dry, then the brushes are worn out in a short time because, in order to reduce transition resistance, they must be forced to the ring with high presg sure,

It is an object of the present invention to provide a brush which rests on the slip ring carrying an oil film. with a ring shaped surface. With such a configuration of the contact surface of 30 the brush, the electric transition resistance is very low and the life of the brush is long. This may be explained by the fact that the comparatively narrow annular surface presses the oil on a very short path outwardly or inwardly and 35 away from the contact surface of brush and ring without necessitating extraordinary great pressure which would increase the wear on the brush.

In order to insure and control lubrication of the slip ring, the brush, according to the present invention, preferably is of tubular configuration and the lubricating oil is supplied to the interior of the brush. This supply may be carried out through openings in a socket in which the brush is slidably located. Any other lubrication of the 45 slip ring, for example by spray oil, should be prevented.

With the apparatus according to the present invention, lubrication is maintained uniform and is easily controlled, the transition resistance of 50 the electric current is held at a low figure, and the wear of the brushes is small and their life is long.

Further and other objects of the present invention will be hereinafter set forth in the ac- 55 companying specification and claims and shown in the drawing which, by way of illustration, shows what I now consider to be a preferred em.- bodiment of my invention.

In the drawing-- Figure 1 is an axial part cross sectional view of 5 an apparatus according to the present invention.

Figure 2 shows part of what is shown in Figure l in large scale, the brush being shown in section. 10

Figure 3 is a longitudinal sectional View of a brush according to the present invention.

The apparatus shown is particularly suitable for use in motive power equipment.

Like parts are designated by like numerals in all gures of the drawing.

I designates the casing into which shaft 2 extends. To shaft 2 a disc 2| is keyed which is provided with an annular rim 4 which carries a magnet winding l0. Rim 4 serves as electromag- 20 netic coupling ring which, if excited, pulls the axially movable armature ring' 3 towards itself and then rotates it, whereby the rotating power is transmitted by friction. The armature ring 3 may also be attracted by means of an annular 26 electromagnet 5 having windings 8 and being rigidly connected with the casing l.

Armature ring 3 is connected to or forms part of a disc the hub of which carries a spur gear, which constitutes the center wheel of a planetary 30 gear. The outer wheel 'l of said planetary gear is formed by a spur gear which is carried by a member which is carried bythe shaft 2. Said last-mentioned member is connected by means of other electromagnetically controlled planetary gears with the drive shaft; these gears are not shown as they do not form part of the present invention. The planetary gear wheels 6 are connected with a support which is also keyed to shaft 2 and which has a hub on which the afore- 40 mentioned center wheel, which forms one part with the armature 3, is revolvable and slideable in axial direction. If the windings 8 are excited while windings l0 are without current, the center wheel is held stationary. The carrier of the planetary gear wheels 6, which carrier is keyed to the shaft 2, drives then the exterior wheel l. If, however, the windings I0 are excited and windings 8 are without current, the carrier 'l and the center Wheel rotate at the same speed so that planetary wheels 6 do not rotate. The exterior gear connected with carrier 'I is then rotated at the same speed as shaft 2. Current is transmitted to the windings 8 by means of stationary sockets 9 whereas the supply of current to the 85 rotating electromagnets takes place through slip ring and brush.

For this purpose one end of the windings lil is conductively connected with ring 4 whereas the other end is connected with the slip ring Il by means of an insulated conductor I0. Slip ring II is connected to the hub of the disc-shaped electromagnet having the rim il, and isolated therefrom and has a cone-shaped configuration so that oil reaching the slip ring is removed to the left, as seen on Figure l., by means of centrifugal forces. Brush I2 rests on the exterior surface of slip ring II.

As is obvious from Figures 2 and 3, brush I2 consists of a tubular body of conventional material, for example a mixture oi copper and coal; the bore It of said body widens out towards the lower end of the brush whereby an annular surface It is formed which contacts slip ring Il.

The tubular body I2 is axially movable in the lower end of the socket I3 which may be made of metal and the upper end of which is provided with an interior thread for accommodating the adjusting screw I8.

In between screw IS and the tubular body I2 a coil spring I'I is situated, the tension of which can be adjusted by means of the adjusting screw I8 and which presses the brush I2 to the slip ring II. Screw I8 has a rod-like extension which extends into spring Il for holding the windings of the latter in place.

The socket I 3 carries at its upper and its lower end bushings lli and Ifl respectively made of insulating material. Bushing I is inserted into an opening of casing I whereas bushing Il sits in a bore of a ring-shaped flange IS which forms one piece together with the casing l and which serves for covering the slip ring II and protecting it against oil spray. On disc 2l a ring-shaped flange 20 is provided which points outwardly and is provided with an edge 2t which facilitates throwing away of oil by centrifugal forces. Edge 2li is arranged as closely as possible to flange I9 in order to prevent passage of oil towards the slip ring II. v

Above the insulating bushing IQ, socket I3 is provided with radial bores I5.

The operation of the device is as follows: The revolving rim ll and the disc 3 continuously throw oil towards the casing, which oil runs down the interior walls of the casing I as indicated by arrows in Figure 2. The oil also wets the exterior of socket I3 and banks up on the upper face of the insulating bushing III. From there the oil enters the interior of socket I3 through the openings I5 and runs down within socket I3 and into the longitudinal bore Iii of the brush I2. In this manner, the oil reaches the slip ring II within the annular face of the brush. The small amounts of oil which pass outwardly in between the edge of the brush and the contact surface of the slip ring flow to the left, as seen on Figure 2, due to centrifugal forces and are thrown ofi the edge 2li so that the slip ring is uniformly covered by a thin lm of oil.

Due to the funnel shaped coniiguration of the outer end of the bore I6, the part actually contacting the slip ring Il is comparatively small. Experience has shown that thereby a low transition resistance is obtained and wear is reduced. This form of the brush also prevents the undesired revolving of the brush in the socket I3.

The exciting current is transmitted to the screw I8 wherefrom it flows through spring Il, holder or socket I3, brush I2, slip ring II and conduit I0 into the windings I0; therefrom the current flows back through the steel mass of the magnet. The extent of the lubrication depends on and is controlled by size and number of the holes I5.

The oil flowing outwardly from the interior of the brush washes the coal dust mud away and also serves for conducting away the heat caused by thefriction of the brushes on the slip ring.

For the supply of oil to the tubular brush holder I3, an oil conduit 23 may be connected to the holes I5. One or more radial clearances 22 may be provided adjacent to the annular contact surface of the brush for better washing action of the oil, as are shown in Figure 3.

While I believe the above-described embodi-a ments of my invention to be preferred embodiments, I wish it to be understood that I do not desire to be limited to the exact details of process, design, and construction shown and described, for obvious modiiications will occur to a person skilled in the art.

I claim:

l. A revolving mechanism having a rotating slip ring and an electricity conducting brush, said brush having a projecting, comparatively narrow annular surface which amounts to only a small fraction of the brush cross section and which slidingly contacts said slip ring.

2. A lubricated revolving mechanism having in combination a rotating slip ring and an electricity conducting brush, said slip ring having an outer surface which is inclined with respect to the axis of rotation of said ring whereby the throwing ofi by centrifugal forces of lubricant reaching said ring is facilitated, said brush having a protruding and narrow annular surface which amounts to only a small fraction of the brush cross section and which slidingly contacts said inclined outer surface of said slip ring and means associated with said brush for lubricating said annular surface.

3. A revolving mechanism having a rotating slip ring and an electricity conducting brush, said brush having a cavity which widens out at one end whereby a comparatively narrow annular surface is formed which slidingly contacts said slip ring.

1i. A lubricated revolving mechanism having a rotating slip ring, an electricity contacting brush, said brush being of substantially tubular configuration and having at one end an annular surface which slidingly contacts said slip ring, a tubular 1ubricant conduit, said brush being inserted into said conduit and slidingly movable therein, said conduit conducting lubricant into the interior of said brush, wherefrom the lubricant iiows through said annular surface onto said slip ring.

5. A. revolving mechanism having a rotating slip ring and an electricity conducting brush, said brush having a substantially tubular configuration, the interior of said brush being flared outwardly towards one end of the brush whereby a narrow annular surface is formed which slidingly contacts said slip ring.

5. A lubricated revolving mechanism having a rotating slip ring, an electricity conducting hollow brush, a hollow socket slidingly holding said brush in its interior and having openings through which lubricant enters the interior of said socket and therefrom the interior of said brush.

7. A lubricated revolving mechanism having a rotating slip ring, an electricity contacting brush,

said brush beingv of substantially tubular conguration and having at one end an annular surface which slidingly contacts said slip ring, a lubricant conduit connected with said brush adapted to conduct lubricant into the interior of said brush, wherefrom the lubricant fiows through said annular surface onto said slip ring, stationary shielding means adjacent to said brush and revolving shielding means adjacent to said slip ring and to said stationary shielding means, whereby the lubricant is prevented from reaching said slip ring except through said brush.

8. A revolving mechanism having a rotating slip ring and an electricity conducting brush, said brush having an annular surface which slidingly contacts said slip ring, said annular surface being broken, whereby lubrication and ventilation, i. e., cooling of said brush is improved.

9. A lubricated revolving mechanism comprising a revolving electromagnet having windings, a rotating slip ring being electrically connected with said windings, an electricity conducting brush having a bore opening out into a cavity at one end whereby a protruding narrow annular surface is formed which slidingly contacts said slip ring.

l0. A lubricated revolving mechanism comprising a casing which houses said mechanism, a revolving electromagnet within said casing and having windings, a rotating slip ring within said casing and being electrically connected with said windings, an electricity conducting brush within said casing which brush is of substantially tubular configuration and has at one end an annular surface, which slidingly contacts said slip ring, a rsubstantially tubular lubricant conduit connected with said casing and slidingly surrounding and holding said brush and being adapted to conduct lubricant from said casing into the interior of said brush, wherefrom the lubricant flows through said annular surface onto said slip rlng.

11. A lubricated revolving mechanism comprising a casing which houses said mechanism, a revolving electromagnet within said casing and having windings, a rotating slip ring within said casing and being electrically connected with said windings, an electricity conducting brush within said casing which brush is of substantially tubular configuration and has at one end an annular surface, which slidingly contacts said slip ring, a lubricant conduit connected fWith said brush adapted to conduct lubricant ,from said casing into the interior of said brush, Wherefrom the lubricant flows through said annular surface onto said slip ring, stationary shielding means adjacent to said brush and revolving shielding means connected with said electromagnets and being situated adjacent to said slip ring and to said stationary shielding means, whereby the lubricant is prevented from reaching said slip ring except through said brush.

JACQUES ELWELL.

Images