US790352A - Shaft-packing. - Google Patents

Description

' PATENTED MAY 23, 1905, W. L. R. EMM T, Y

SHAFT PACKING. APPLIGATION FILED SEPT. 6, 1904'- 2 SHEETS-SHEET .1.

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-m.790.s52. v PATENTED MAY 23,1905.

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SHAFT PACKING.- APPLICATION FILED SEPT. e. 1904.

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WILLIAM L. R. EMMET, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEWV YORK.

SHAFT-PACKING- SPECIFICATION forming part of Letters Patent No. 790,352, dated May 23, 1905.

' Application filed September 6, 1904:. Serial No. 223,383.

To all whom, it may concern:

Be it known that I, WILLIAM L. R. EMMET, a citizen of the United States, residing at Schenectady, in the county of Schenectady and State of New York, have invented certain new and useful Improvements in Shaft-Packings, of which the following is a specification.

This invention relates to packing for arotating shaft at the point where it emerges from a casing containing an elastic fluid under pressure. It has especial reference to making a steam-tight joint where the shaft of a steam-turbine passes out of the casing containing the bucket-wheels, and for the sake of simplicity it will be described in thatconnection only.

The invention consists in a certain construction and arrangement of packing-rings with means for supplying and conveying away steam Whose tension keeps the rings tightly pressed against the surfaces of the joint, all as hereinafter set forth and claimed.

1n the accompanying drawings, Figure 1 is a longitudinal section of a portion of a turbine embodying my invention. Fig. 2 is an enlarged view of the packing. Fig. 3 is a plan view of the same, partly in section; and Fig. 4 is a section through the check-valve.

The turbine selected for illustration is of the vertical (Curtis) type. The upright shaft 1 is centrally arranged in a casing 2, divided into stages by diaphragms 3. On the shaft are mounted the bucket-wheels 4:, carrying buckets 5, to which steam is supplied through nozzles 6, the upper one communicating with the valve-chest 7 and the others each receiving steam from the preceding stage. The ab solute pressures in the several stages decrease from the upper to the lower. My invention relates to the packing which makes a steamtight joint where the shaft passes out of the upper stages through the top 8 of the casing. A shoulder 9 is formed in said top concentric with the shaft and transverse thereto, and a ring 10, of packing material, is supported on said should er. -The preferred material is gascarbon .containing. a certain percentage of graphite. It is molded in segments of firing, Which does not quite touch the shaft, and is held in a flanged annular metal holder 11, made in halves, fastened together by bolts 12. A suitable distance above the shoulder 9 is an annular plate 13, supported on the top 8 with its inner edge close to but not touching the shaft. The under surface of this plate affords a bearing-surface transverse to the shaft for a packing-ring 14, similar to the ring 10 and held in a holder 15. Between the two holders is a shallow space in which are located springs 16 to keep the rings seated on their respective bearing-surfaces on the shoulder 9 and plate 13.

If desired, auxiliary packing-rings and bearing-plates may be piled up on top of the plate 13. The drawings show one such plate 17 resting on the plate 13 and affording a bear ing-surface for a packing-ring 18, received in a flanged annular holder 19 and kept up to its seat by springs 20.

The segments of the packing-rings are held firmly together by resilient bands, such as the I endless helical springs 21, lying in circumferential grooves in said rings. Should the segments get loose in the holders, owing to the unequal expansion of the carbon rings and the metal holders, the springs retain the rings in shape.

There is a constant slight leakage of steam from the casing into the space between the two rings 10 14, and this serves to keep them, and especially the latter, forced to their seats, so that very little, if any, of the steam can escape. Should it pass the ring 14, it will be checked by the ring 18, and in order to lead away any such steam a pipe 22 is run from the space below the ring 18 to one or more of the lower stages of the turbine. A valve 23 is provided to direct the steam into the proper stage, depending on its pressure. This may be a three-way hand-valve or an automatic pressure-controlled valve. An automatic valve 24: may be inserted in the pipe to prevent the suction of air in past the ring 18 in case the steam-pressure in the pipe falls below the atmospheric pressure. 4

The leakage of steam under the lower ring 10 may be objectionable under some circumstances, tending to roughen the ring and shift it on its seat. To avoid this, a small duct 25 may be made in the top of the casing con-necting the first stage with the space between the rings 10 14:. An adjustable check-valve 26 is introduced to govern the flow of steam through this duct.

Instead of taking steam from the first stage it,may be supplied to the space between the rings direct from the boiler, if desired.

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

1. A shaft packing, comprising annular bearing-surfaces adjacent and transverse to the shaft, packing-rings of suitable material encircling said shaft and bearing on said surfaces, and means for admitting elastic-fluid pressure between said rings.

2. A shaftpacking, comprising annular bearing-surfaces adjacent and transverse to said shaft, packing-rings of suitable material concentric with said shaft and bearing on said surfaces, flanged annular holders for 'said rings, springs to force said holders apart, and means for admitting steam between said holders.

3. A shaft packing, comprising annular bearing-surfaces adjacent and transverse to said shaft, segmental packing-rings concentric With said shaft and bearing on said surfaces, a resilient band around each ring, a flanged annular holder for each ring, and means for admitting steam between said holders.

4. The combination with a shaft, of a casing having a shoulder concentric with said shaft, a plate secured to the casing a short distance from said shoulder, shaft-packing rings bearing against said shoulder and plate, one or more auxiliary bearing-plates secured to the aforesaid plate, one or more auxiliary packing-rings cooperating with said plate or plates, and means for supplying steam to press the rings against said shoulder and plates.

5. A packing for a steam-turbine shaft, comprising carbon packing-rings concentric with said shaft, bearing-surfaces cooperating with said rings, a turbine-casing having a duct leading from inside the casing to the space between said rings, and a check-valve controlling said duct.

6. The combination with a steam-turbine, of packing-rings for the shaft, means for admittin g steam to the space between said rings, and an escape-pipe leading to one or more of the lower stages of the turbine.

7. The combination with a steam-turbine, of packing-rings for the shaft, means for admitting steam to the space between said rings, an escape-pipe leading to one or more of the lower stages of the turbine, and a valve for determining to which stage the exhaust-steam will be admitted.

8. The combination with a steam-turlfine, of packing-rings for the shaft, means for admitting steam to the space between said rings, an escape-pipe leading to one or more of the lower stages of the turbine, and an automatic valve for closing said pipe when the steampressure in it falls below the atmospheric pressure.

In witness whereof I have hereunto set my hand this 2d day of September, 1904.

\VILLIAM L. R. EMMET.

Witnesses:

BENJAMIN B. HULL, HELEN ORFoRD.

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