Centrifuge drive arrangement

Nov. 17, 1959 w. wilsmann 2,913,169

CENTRIFUGE DRIVE ARRANGEMENT

Filed Sept. 17, 1956 2 Sheets-Sheet 1

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FIG. I

INVENTOR.

WLHELK WLSMWT

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ATTof^^Eys

Nov. 17, 1959 w. wilsmann 2,913,169

CENTRIFUGE DRIVE ARRANGEMENT Filed Sept. 17, 1956 2 Sheets-Sheet 2

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FIG.2

INVENTOR

WILHELM WILSMANN

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ATTORNEYS

2,913,169

Patented Nov. 17, 1959

United States Patent Office

2,913,169

CENTRIFUGE DRIVE ARRANGEMENT

Wilhelm Wilsmann, Oelde, Westphalia, Germany, assignor to Westfalia Separator A.G., Oelde, Westphalia, Germany, a corporation of Germany

Application September '17,1956, Serial No. 610,277

Claims priority, application Germany September 19,1955

Claims. (Cl. 233—23)

This invention relates to an improved centrifuge drive arrangement. The invention more particularly relates to an improved drive arrangement for centrifuges provided with a vertical drive spindle which is directly driven by an electric motor.

In centrifuges, such as centrifugal separators, which are directly driven by an electric motor, the centrifuge generally has a vertical drive spindle rotatably mounted by means of an upper and lower bearing in a centrifuge frame. The centrifugal bowl is mounted above on the vertical drive spindle, and the electric drive motor is mounted below the drive spindle in axial alignment therewith and directly connected to the drive spindle, as, for example, by means of an elastic coupling. The lower bearing, which is generally developed as a selfaligning swing bearing, supports the weight of the centrifugal drum and the spindle in an axial direction, while the upper bearing is developed with radial elasticity in order to be able to take up the radial oscillations of the spindle during operation. The bearings are generally grease-lubricated bearings, as for example, ball or roller bearings which are packed with grease to assure smooth and easy operation.

In such an arrangement, since the bearings and the drive motor are arranged below the centrifugal drum or bowl, a danger exists that liquid will penetrate into the bearing and into the motor winding if the bowl overflows. This may occur, for example, if the bowl is fully filled before it has reached the full speed of rotation. Thus, for example, when the centrifuges are. used for the separation of cream it is customary to add skimmed milk before the centrifuge is stopped in order to displace the cream out of the bowl. In this connection, the bowl often overflows with the liquid entering the centrifuge frame and penetrating the bearings and the motor. Also, when cleaning the centrifuge, the washing liquid may penetrate the bearings and motor windings. The penetration of the moisture into the bearings tends to reduce the lubricating effect of the grease, and, in instances where the centrifuge stands for a long time without operation, it also tends to promote rust formation. In this way the satisfactory operation of the centrifuge is greatly impaired and the life decreased. The higher frictional resistances caused by the decrease in the lubrication results in a greater temperature rise and a greater wear of the bearings. The penetration of the moisture into the electric motor, besides causing wear of the bearings of this motor, leads to a reduction of the insulation resistance of the winding and thus to a decrease in the life of the motor and often short circuits it.

One object of this invention is a bearing and motor arrangement for a centrifuge of the above-mentioned type which avoids the above-mentioned disadvantages. This, and still further objects will become apparent from the following description read in conjunction with the drawing, which shows a vertical section of an embodi2 ment of a bearing and motor arrangement in accordance with the invention. .

The invention is applicable to cenrtifuges having a vertical drive spindle rotatably mounted by means of 5 an upper and lower grease-lubricated bearing in a centrifuge frame and provided with an electric motor vertically mounted below the drive spindle and directly connected thereto for drive actuation.

In accordance with the invention, the centrifuge 10 frame defines an upper and a, lower chamber surrounding the upper and lower bearing, respectively. These chambers define liquid-retaining troughs at their bottom portion having outlet drain means. The upper bearing, and preferably both the upper and lower bearings, are 15 protected by protective sleeves which surround the same and preferably terminate with. their Upper ends closely adjacent the spindle.

Fig. 1 is a vertical axial section of the structure embodying this , invention. Fig. 2 is a further showing of 20 the same showing the feature of the lever bearing protection from moisture.

Referring to the embodiment shown in the drawing, the drive shaft 1 of the electric drive motor 2 is connected by. the flexible coupling 3 with the vertical drive spindle 25 4 which carries the centrifugal bowl 5. As the construction of the bowl or drum 5 is conventional and the invention solely relates to the mounting of the vertical drive spindle 4 and of the motor 2, the constructional details of the bowl and the Other portions of the 30 centrifuge have been omitted for the sake of clarity.

' The flexible coupling between drive shaft of the motor 1 and the vertical spindle 4 as shown, consists of a rubber disc which is connected on one side to the drive shaft of the motor by one off-set pin and connected to the 35 spindle 4 by a counter-balanced opposed off-set pin.

Such coupling arrangement. is conventional, and any other known or conventional arrangement may be used which will take up the shocks of starting and stopping and during operation, and which will allow a limited 40 flexing of the spindle with respect to the motor during operation.

The vertical spindle 4 is supported in the centrifuge frame 16 by means of an upper grease-lubricated ball bearing 6 and a lower grease-lubricated ball bearing 7. 45 The centrifuge.16 defines an upper chamber 19 and a lower chamber 20, which have the horizontally extending partitions 17 and 18, respectively, which form liquidretaining troughs at the bottom of the chambers and which support the upper and lower bearings, respectively. 50 An outlet drain pipe 22 for liquid leads from the trough of the upper chamber 19 and an outlet drain 25 leads from the trough of the lower chamber 20, so that any liquid falling in these troughs will run out of the same through these drain outlets.

The frame 16 additionally defines an annular, space 26 below the lower bearing 7 and the lower chamber 20. An outlet drain pipe 27 leads from this annular space to the outside, extending through the drain 25.

The lower ball bearing 7 is formed as a self-aligning 60 swing bearing which will allow a limited pivoting of the spindle 4 with this bearing acting as a point of pivot. Surrounding the bearing 7 is a protective sleeve 12, in which the outer race of the bearing is mounted. The sleeve 12 is bell-shaped and mounted in the parti65 tion 18. The upper portion of the protective sleeve 12 closely surrounds the spindle and a labyrinth seal cap 10 is mounted on the spindle, sealing the upper end of the protective sleeve 12 from moisture. The bottom of the protective sleeve 12 is sealed by means of a bottom 70 cover plate 13, which is held in place by the expanded snap ring 15, which fits into an appropriate groove in the inner surface of the sleeve.

2,913,169

The upper bearing 6 has its outer race mounted in a protective sleeve 8, which is bell-shaped and which closely surrounds the spindle at its upper end and which is provided with a cover plate 11 at its lower end maintained in place by an expanded snap ring 14. The protective sleeve 8 is mounted in a second cylindrical sleeve 24, which is secured by means of its upper lip to the partition 17. The second sleeve 24 is of smaller diameter than the opening through the partition 17 and is resiliently maintained in place by springs which allow resilient lateral movement. A labyrinth cap seal 9 surrounds the spindle 4, sealing the upper end of the protective sleeve 8. The cap 9 also co-operates with the flange 23 to form a double labyrinth seal. The flange 23 is screwed to the partition 17 and holds the second sleeve 24 secure from axial movement. The second bearing sleeve 24 is provided with openings in the side wall thereof, so that moisture penetrating the labyrinth seal caused by the cap 9 niay run over the outer surface of the protective sleeve 8 through these openings into the lower chamber 20.

The resilient mounting of the upper bearing in combination with the swing arrangement of the lower bearings allows the limited necessary swing of the spindle 4 during operation.

It is also possible to eliminate the labyrinth cap 10 and to extend the protective sleeve 12 into the second cylindrical sleeve 24.

In operation, the electric motor 2 drives the vertical drive spindle 4 in the conventional manner, which causes rotation of the centrifugal bowl or drum 5. Any liquid over-flowing from the bowl will enter the chamber 19, collect in the trough at the lower portion of this chamber, and will be discharged through the discharge pipe 22. The protective sleeve 8 and the labyrinth cap seal 9 protect the bearing 6 from this liquid. If any moist air or liquid passes through the upper labyrinth seal formed by labryrinth cap 9, the same will merely pass down over the outer surface of the protective sleeve 8 through the opening in the second sleeve 24 and into the lower chamber 20, where the same will collect in the lower trough and drain off through the drain opening 25. This also holds true for moisture which may penetrate the upper labyrinth seal and condense in the lower chamber.

The lower bearing is protected from this moisture by means of its protective sleeve 12 and cap 10. Should, however, any moisture enter through the bottom bearing 7, this moisture will accumulate in the annular space 26 and be discharged through the small pipes 27. The portion where the drive shaft and coupling extend through the annular chamber is protected by a labyrinth cap similar to that used in connection with the bearing.

The bearings and the motor are thus positively protected from the deleterious effects of the liquid which overflows from the bowl and the life of the bearing shaft, and the motor is greatly increased.

While the invention has been described in detail with reference to the specific embodiments shown, various changes and modifications will become apparent to the skilled artisan which fall within the spirit of the invention and scope of the appended claims.