US2038731A - Driving mechanism - Google Patents

Description

April 28, 1936. G. E. GUNDERSON I DRIVING MECHANISM Filed Sept. 13, 1935 am Q I meme Apr. 28, 1936 mar-r131) STATES PATENT OFFlCE 2,038,131 4 DRIVING LIECHANISM Gunner E. Gunderscn, Chicago, Ill., assignor to Foote Gear Works, Inc., Chicago, 111., a corporation of Illinois Application September s, 1933, Serial No. 689,202 1 Claim. (01. 74-425) The present invention relates generally to drlvvices, and comprises an electric motor and speedreducing means in the form of worm gearing .which is driven by the motor and consists of a worm on one end of the armature shaft of the motor and a worm wheel in mesh with the worm.

Heretofore, it has been customary in the manufacture of driving mechanism of this type, to mount the worm gearing in a. housing atone end of the motor housing and to secure the worm to the armature shaft of the motor by means of a-transverse driving pin, a set screw or any other type of rigid driving connection. In practice it has been found that with a connection of this character between the worm and the armature shaft, the life of the motor is comparatively short due to the fact that the armature shaft is subjected to a certain amount of strain and end thrust from the worm, and is not free so that the armature can float within, and-center itself with respect to, the field windings of the motor.

One object of the invention is to provide driving mechanism of the type under consideration which is generally animprovement upon, and is i more efllcient in operation than, previously designed driving mechanisms of the same general character, by virtue of the fact that the worm is' supported at the ends'thereof by ball bearings in the housing for the worm gearing'and is connected to the armature shaft of the motor by a key and groove connection which eliminates end thrust on the shaft, absorbs strain and permits,

the armature to float and center itself with respect to the field windings of the motor.

Another object of the invention is toprovide driving mechanism of the aforementioned char-- acter in which the housing for. the worm gearing is formed integrally with the housing for the electric motor and embodies a simple and im'-" proved bearing arrangement for the worm and novel means for lubricating the key and groove connection which serves as the driving medium for the worm and permits the armature to float and center-itself with respect to the field windings of the motor. 5 v 'A further object oftheinvention is to pro- .vide. driving mechanism of-the electric, motor,

. and worm gear type which is eflicient and reasonable cost: I

in operation and may be manufactured in low advantages and characteristics of the present construction of driving mechanism will be apparentfrom a consideration of the following detailed description.

I The invention consists in the several novel fea-- 5 tures which are hereinafter set forth and are more particularly defined by the claim at the conclusion hereof.

In the drawing which accompanies and forms which like numerals of reference denote corresponding parts throughout the several views:

Figure l is a view partly in side elevation and partly in longitudinal section of driving mechanism embodying the invention; and 15 Figure 2 is a transverse section taken on the line 2-2 of Figure 1 and illustrating in detail the manner in which .the worm wheel is supported in. the housing for the worm gearing. The driving mechanism which forms the sub- 20 ject matter of the invention is adapted for use in connection with any apparatus or mechanical device requiring a power unit with speed reducing means. It is essentially a unitary structure and consists of an electric motor 3 and worm gearing 25 4. The motor is adapted to be supported on a rounds the fieldwindings and the armature, as,,

shown in Figure 1 of the drawing,'and consists of 30 a cylindrical side member 9 and a pair of cast metal end members In and i I. The end member in embodies at the centralpart thereof a bearing l2 and fits against one end of the side member 9;

The end member ll fits against the other end of the side member of the motor housing and is provided with a central aperture l3. Bolts ll extend between the end members Ill and l I and serve to hold the latter in clamped relation with respect to the cylindrical side member 9. The field wind- 40 ings I are centrally positioned in the cylindrical side wall 9 of the motor housing and are supported by bolts or pins which extend longitudinally of the motor housing and are supported at the ends thereof by bosses' i5 which are formed 45 integrally with, and project inwardly from, the end members l0 and II. Thearmature 8 is disposed within the field windings I and embodiesa shaft it. One. end of the shaft is joumalled in the bearing l2 at the central portion-of the end 50 member L The other end of the shaft extends through the aperture ii in the central portion of the end member II and is supported, as hereinso that the armature is free to 'rotate'inrc'aponaetoiiowof current or electrical I energy through the field windings I. An oil seal fits within the aperture l3 and around the armature shaft, and prevents oil from entering the motor housing via the aperture. This seal is held in place between an inwardly extending flange I! at one side of the aperture l3 and fiber spacing rings H at the other side of the aperture.

integrally with the end member ll of the motor housing 6 and comprises a semi-cylindrical top wall 23, a bottom wall 24 and an outer end wall .25. The top wall I3 of the housing for the worm gearing surrounds the end of the armature shaftwhich projects through the aperture l3, and is joined at the inner end thereof. to the central The outer end portion of the end member ll. of the semi-cylindrical top wall 23 is closed by-a cap 26 which is removablyheld in place by means of cap screws 21 and embodies an inwardly ex tending annular fiange 23. I This flange, as shown in Figure 1 of the drawing, fits slidably within, the

outer end of the semi-cylindrical top Wall 23 of the housing for the worm gearing. The bottom wall 24 is arcuate andis joined to the lower portion of theend member H of the, motor housing and the lower end of the outerend wall 25. The lower portion of the end member I] formsthe inner side wall of the housing for theworm gearing and defines with the bottom wall 24 and the outer 'end wall 25, a substantially cylindrical, transversely extending compartment 29 for the worm wheel 2|. The sides of the housing 22 are closed by a pair of circular side plates 30 and 3|. These plates close the ends of the compartment 29 for the worm wheel 2| and are removably secured in place by means of cap screws 32.

bore 20 through which extends the end of the armature shaft that projects through the aperture l3 and is surrounded by the semi-cylindrical top wall 23 of the housing 22. The bearing 33 is associated with a vertically extending, centrally apertured'pa'rtition 35 in the end of the top wall 23 adjacent to the end member H of the motor housing 6, and consists of an outer race 33, an inner race 33' and an annular series of balls 33 between the two' races. The partition 35 is formed integrally with the top wall of the housing for the worm gearing and extends around the projecting end of the armature shaft. The outer race of the ball bearing 33 is connected by'a drive fit to the portion of the partition that forms the central aperture. The inner race 33 is shrunk or otherwise secured around a reduced stem 36 on the inner end of the worm 20, that is,-the.end

adjacent to the electric motor 6. The ball bearing 34 is associated with the removable cap 26 at the outer end of the top wall of the housing 22 and consists of an outer race 34*, an inner race 34 and an annular series of balls 34 between the two races. The outer race 34 is driven into connected relation with the inner periphery of the inner end of the annular flange 28 of the cap 26. The inner race 34 is shrunk or otherwise secured around a reduced stem 31 on the outer end of the worm 20. Byemploying the bearings 33 and 34, the worm 2D is supported independently of the projecting end of the armature shaft and is held or confined against longitudinal movement in the housing 22 for the worm gearing. The worm is driven by the armature shaft through the me- The worm 20 is journalled in a pair of ballbearings 33 and 34, has a longitudinal central diumof a longitudinally extending key 33. The latteris secured to, and extends longitudinally of, the projectingend 'or the armature shaft and worm. As aresult of this arrangement and by supporting the worm in gearings independently of the armature shaft, the armature is not subjected to any end thrust from the worm and is free to fioat within and center itself with respect to the field windings 1. In addition, there is a complete absorption of any and all strain resulting during operation of the driving mechanism and the life of the electric motor is thereby prolonged or increased. The key and groove connection between the projecting end of the armature shaft and the worm exemplifies a simple driving connection whereby the worm is driven from the armature shaft and at the same time,. the armature, shaft is permitted to slide longitudinally of the worm so that the armature may float within and adjust itself to the field windings, as previously pointed out. I

The worm wheel 2| meshes with, and is driven by, the worm 20 and is keyed or otherwise fixedly secured to a transversely extending drive shaft 39. This shaft is journalled in a pair ,of ball bearings 40 and 4| and is arranged so that one end thereof extends through a central aperture 42 in the side plate 3|. The ball bearing 40'is associated with a side plate 30 and is carriedby an annular, inwardly extending flange 43 in the central portion of said side plate. The ball bearing 4| is associated with the side plate 3| and is carried by an annular flange 44. The latter, as shown in Figure 2 of the drawing, is formed in-:

46. This hole, as'shown in the drawing, is normally closed by a screw plug 41. When the hous-; ing 22 is filled with. lubricant, the drive connection between the projecting end of the azmas ture shaft and the worm is lubricated by reason of the fact that a. certain portion of the lubricant flows into the space within the annular flange 28 of the cap 26 via the channel between the inner aridouter races of the ball bearing 34, and then passes into contact with the key 38 in the groove 20".

When current or electrical ,energy'is supplied to the field windings of the motor, the armature is rotated and efi'ects drive of I the shaft 39 through the medium of the worm 20 and the worm wheel 2| whichconstitute speed reducing means and cause the shaft to rotate at a reduced speed with respect to the armature shaft. During operation. of the driving mechanism, the worm 20 is held or confined against end thrust by the ball bearings 33 and 34, and the armature is allowed to float, that is, move longitudinally relatively to the field windings, by reason of the key and groove driving connection projecting between the end of the amature shaft and the worm. When it is desired to remove the worm 20 from the housing 22, it is only necessary to tegrally with, and extends inwardly from, the

remove the cap 26 and to withdraw the worm together with the bearings 33 and 84 through the outer end of the semi-cylindrical top wall 23 of the gearing housing.

The herein described driving mechanism consists of but a comparatively small number of parts and hence may be produced at a low and reasonable cost. It is exceedingly emcient due to the specific manner in which the worm is journailed in the gear housing and thearmature shaft is connected to drive the worm, and incorporates a construction whereby ready accessibility is derived to all the operating parts.

The invention is not to be understood as restricted to the details set forth, since these may be modified within the scope of the appended claim, without departing from the spirit and scope of the invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is:

In driving mechanism of the character de-- scribed, thecombination of an electric motor embodying a housing with an/ aperture in one end wall thereof and comprising windings fixed in the housing, a rotatable armature within the -windings and rotatable on an horizontal axis and a shaft for the armature with one end there of projecting outwardly through the aperture in said one end wall of the housing, a second housing located adjacent to said one end wall of the motor housing and comprising a pair of sides, a substantially semi-cylindrical top wall around the projecting end of thearmature shaft, having-one end thereof formed integrally-withsaid one end wall of the motor housing and embodying a depending centrally apertured partition around the projecting end of the armature shaft and spaced inwardly from the apertured end wall of the motor housing, and a removable cap at the other end oi the semi-cylindrical top wall and in alignment with thearmature shaft, a worm disposed in said semi-cylindrical top wall between the partition andthe cap and having reduced cylindrical ends and a longitudinal bore therethrough through whichthe projecting end of the armature shaft extends, means for supporting the worm independently of the armature shaft comprisinga pair of ball bearings carried by the partition and cap respectivelyland applied to the reduced cylindrical ends of the worm so that the worm is held against axialdlsplacement in said second housing, a loose key and groove connection between said projecting end of the armature shaft and the worm whereby the shaft serves to drive the worm in response to rotation of the armature but is free to slide longitudinally relatively to the worm and thus permits the armature to float, a worm wheel mounted in the second housing between the sides and arranged so that it meshes with and is driven end wall of the motor housing for preventing oil from passing from said second housing into the motor housing while at the same time permitting of longitudinal movement of the armature shaft.

GUNNER E; GUNDERSON.

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