Open Drip-Proof Machinery Cooling System Using Totally Enclosed Type Bearing Brackets

In the past, housings for rotating electric machinery had utilized a frame and shaft bearing bracket combination to provide an open drip-proof enclosure. In such prior art structures, the frame and shaft bearing brackets were specially designed and suitable only for such open drip-proof applications. A new frame member and new bearing brackets were required when a totally enclosed structure was required. This necessitated a separate inventory of such machinery enclosure parts and resulted in additional cost and complexity for rotating electric machinery manufacturers.

In addition, such open drip-proof structures, particularly in the bearing brackets, had relatively small inlet air apertures, reducing cooling effectiveness. Finally, such prior art inlet apertures conventionally were located below the shaft centerline, often near the base of such machinery when it was mounted for horizontal shaft operation, thus increasing the possibility of contamination of such machinery by dirt or other foreign material resting on the surface on which such machinery was mounted.

The present invention overcomes these disadvantages of the prior art open drip-proof structures by providing for utilization of totally-enclosed type bearing brackets in a new open drip-proof construction which provides for an air inlet aperture permitting the intake of air above the shaft center line. This new construction greatly increases the effective cooling, and reduces the probability of contamination by dirt or other debris resting on the machinery mounting surface in horizontal shaft applications, and reduces the number of parts needed for inventory by allowing the use of totally enclosed bearing brackets in open drip-proof applications. The present invention is useful for any electric machinery which uses cooling air, e.g., motors, generators or electromagnetic clutches or brakes.

FIG. 1A shows a section end view of a shaft bearing bracket of prior art construction.

FIG. 1B shows a side view of a prior art construction partially cut away to show interior air flow.

FIG. 1C shows a section view of the frame member of FIG. 1B illustrating the exhaust path for cooling air in this prior art structure.

FIG. 2A shows a partial cut away side view of an embodiment of the present invention illustrating the features of the inlet air flow passageway structure.

FIG. 2B is an end view of the frame member of FIG. 2A.

FIG. 2C is a section view through the frame member of FIG. 2A showing outlet air pathways.

FIG. 3 is a partial cut away side view of an alternative embodiment of rotating electric machinery illustrating the inlet air flow passageway structure of the present invention.

FIG. 4 is a fragmentary view of a still further alternative embodiment showing a structure suitable for vertical shaft mounting.

Referring now more particularly to FIGS. 1A-C, a prior art open drip-proof motor enclosure 10 may be seen. Enclosure 10 has a frame member 12 and a pair of open drip-proof type bearing brackets 14, 16 each respectively carrying a bearing 18, 20 by which a shaft 22 is mounted for rotation within housing or enclosure 10. Air enters enclosure 10 by way of apertures 24-28 in bracket 14, and by way of apertures 30, 32 in bracket 16. After entering enclosure 10, cooling air passes across rotor mounted fan 34, along stator 36, and exits through ports 38.

Referring now to FIGS. 2A-C, an open drip-proof version of rotating electric machinery utilizing the present invention may be seen. FIG. 2A shows a horizontal shaft electric motor 40. Motor 40 has a shaft 42 mounted for rotation by bearings 44, 46 located in bearing brackets 48, 50. A rotor 52 is mounted on shaft 42 for rotation therewith. Rotor 52 carries fans 54, 56 designed to impel air radially toward a stator 58 located on a frame member 60. Frame member 60 has a pair of air flow or inlet rings 62, 64 mounted at opposite ends thereof. Alternatively, single-ended cooling may be accomplished by using an air flow ring at only one end of the machinery enclosure. Ring 62 may be seen in an end view in FIG. 2B. Frame member 60 further has a plurality of lands or spacers 66 upon which bearing bracket 48 is mounted. Bracket 48 is secured to frame member 60 by bolts 68 secured through lands or bosses 66 which may be formed in one piece with frame 10 or which may be separate pieces. Bearing bracket 50 is secured to frame 60 in a similar fashion. Referring now more particularly to both FIGS. 2A and 2C, a plurality of ports 70 are provided to permit the egress of cooling air from motor 40.

In this embodiment, cooling air enters motor 40 between bearing bracket 48 and ring 62 in a generally axial direction. Cooling air next progresses radially inward between surface 72 of frame member 60 and interior surface 74 of bracket 48. Cooling air next passes between a stator shroud or air deflector 76 (formed as a section of a toroidal surface formed of sheet metal, fiberglass or other suitable material) and interior surface 75 of bearing bracket 48. Fan 54 then receives the cooling air flow and directs it radially outward and then generally axially across stator 58. Finally, the cooling air flow exits at ports 70. It is to be understood that fans 54, 56 provide the motive force for cooling air in this design.

Referring now to FIG. 3, an alternative embodiment may be seen. In this embodiment, an optional shaft-mounted fan 78 may be used to direct air to both stator 80 and rotor 82. Rotor 82 has axial passageways 84 and radial passageways 86 for conducting cooling air through rotor 82. Stator 80 also may have radial passageways 88 aligned with radial passageways 86. A rotor mounted fan 90 may be used in place of or in addition to shaft mounted fan 78.

Referring now to FIG. 4, a still further embodiment suitable for vertical shaft applications may be seen. In this embodiment, ring 62 is omitted from frame member 60'. A drip cover 100 preferably formed of sheet metal may be secured to bracket 48 by drive screws or rivets 102 or, alternatively, may be secured to lands or spacers 66 if desired. Alternatively cover 100 may be cast as a single piece with frame member 60'. In vertical shaft applications the air outlet ports will be made vertically drip-proof by one or more sheltering members such as louvers or awnings, preferably formed of sheet metal in a conventional manner.

The invention is not to be taken as limited to all of the details thereof, as modifications and variations thereof may be made without departing from the spirit or scope of the invention. For example, the air passageway 92 formed between bracket 50 and ring 64 may be made into an air outlet passageway by extending air deflector 94 as shown by the double-dashed lines 96 while at the same time extending fan 56 to the dashed position 98. With such an arrangement ports 70 may be closed off. As a still further alternative ports 70 may be used as air inlets and air passageways 92, 93 as air outlets.