US1006714A - Elastic-fluid turbine. - Google Patents

Description

T. BELL. ELASTIC FLUID TURBINE.

APPLICATION FILED APR.15, 1910. 1,006,714. Patented 0@1.24,1911.

UNITED STATEfl PATENT OFFIQE.

THOMAS BELL, OF CLYDEBANK, SCOTLAND, ASSIGNOR T0 GENERAL ELECTRIC COM- PANY, A CORPORATION OF NEW YORK.

ELASTIC-FLUID TURBINE.

Specification of Letters Patent.

Patented Oct. 241, 1911.

Application filed April 15, 1910. Serial No. 555,756.

To all whom itmay concern:

Be it known that I, THOMAS BELL, a subject of the King of Great Britain, residing at Olydebank, county of Dumbarton, Scotland, have invented certain new and useful Improvements in Elastic-Fluid Turbines, of which the following is a specification.

The present invention relates to elastic fluid turbines and more especially to turbines ofthe impulse type, wherein a plurality of wheels is provided that are located within a suitable casing and are separated from each other by partitions or diaphragms through which the shaft carrying the wheels passes. The partitions are supported by the Wall of the casing. Between the wheel compartments or stages are noz- Zles that convert a certain portion of the pressure of the motive fluid into velocity and discharge it against one or more rows of vanes or buckets carried by the adjacent wheel. Since there is a conversion of pressure into velocity it follows that a pressure difference must be maintained between one wheel compartment and the next. This means that steam will tend to lead through the shaft opening in the diaphragm from one compartment to the next, which steam is lost to the compartment from which it leaks. It is the practice to provide packing rings or leakage reducing devices to prevent this leakage. These packings may be and sometimes are the source of a very great deal of trouble and loss in efficiency of the turbines owing to their failure to 'function properly. Inasmuch as they are located within the turbine casing where they are out of sight and also inaccessible, there is no satisfactory way of telling whether any particular packing is operating satisfactorily or not after it is installed without taking down the machine and making careful measurements. Owing to the fact that changes in temperature brought about by load changes frequently cause unequal expansion and contraction of the parts, provision must be made to compensate therefor and also to compensate for the whipping of the shaft which sometimes takes place.

By means of my improved construction, I am able to overcome the objectionable effects of expansion and contraction and of whipping and to provide a packing or leakage reducing device which is simple and rugged in construction, is not liable to get out of order, will expand and contract freely with its associated parts, will maintain the predetermined minimum clearance with the rotor, and may be repaired at a small expense in case of injury or wear.

In the accompanying drawing which illustrates one of the embodiments of my inven tion, Figure 1 is a sectional view of a part of a diaphragm and packing ring; Fig. 2 is a view partly in elevation and partly in section of a packing ring; Fig. 3 is an enlarged detailed view showing the serrations in the bore of the packing ring, and Fig. 4: is a detailed view showing a joint between two segments of the ring.

1 indicates the diaphragm or partition which separates one wheel compartment or stage from another in a multistage elastic fluid turbine. This diaphragm has a central bore 2 through which the wheel-carrying shaft 3 extends. This shaft is made of steel and may be made hollow or solid depending upon the character of the turbine. In marine work it is usually made hollow and of large diameter with the result that the packing problem presents more difliculties than with machines of corresponding size used for a land purpose where the speed is greater and the shaft is smaller in diameter. Located in the bore of the partition is a holder comprising a flange 1 that is bolted or otherwise secured to the diaphragm and an annular portion 5 that contains an annular recess to receive the segmental packing ring as will appear later. The holder is split in an axial plane. The annular portion 5 of the holder is connected with the flange 4: by a portion 6 that is restricted in its cross-sectional area to render it somewhat flexible so as to permit the member 5 to yield radially outward in the event that the packing is struck by the shaft or some part revolving therewith. In other words, when the shaft whips, the holder, instead of breaking, will yield. It is to be noted that the port-ion 5 is located at one side of the diaphragm so that its movements are not confined or restricted by the wall of its bore. The holder is preferably made either of cast iron or steel so that it will expand and contract in the same ratio as the shaft 3, and thus the clearance between the adjacent surfaces will tend to remain the same under all circumstances.

In the groove or recess inthe bore of the holder is mounted a segmental packing ring 7 made up of a number of parts, six being shown in the present embodiment. The ring is preferably made of brass or other suitable comparatively soft metal, or metallic composition, so that in case the shaft rubs it will be worn away and not injure the shaft. The packing ring, as above stated, is made up of segments 8, the ends of which are pro- 1 vided with a tongue and groove joint, the abutting ends of the parts being separated by the clearance 9,. so that the segments can freely expand and contract and in so doing slide one upon the other. It is, of course, to be understood that this movement isvery slight, but, nevertheless, it is of very great importance to make provision for it, since otherwise the ring might seize the shaft and cause injury. By using a tongue and groove joint there is no direct passage for the steam to leak through. The segments of the ring are supported in a peculiar manner which permits of the parts expanding and contracting at will without the strain of one part or portion beingv transferred to another part or portion. They are also prevented from rotating with the shaft, or from moving so that the end clearances would be all at one point instead of distributed as shown. As shown, the segments are comparatively short and on that account, a relatively small number of securing means is provided. In the illustration, three screws are provided for each segment. The center screw 10 makes a snug fit in the holder and also in the ring and forms an anchor, while the screws 11 make a snug fit in the ring and a loose fit in the holder. Inasmuch as the heads of the screws are larger than the body, said heads will serve to prevent any of the segments from moving toward or away from the shaft but will not interfere with the segment when it expands or contracts in a circumferential direction. Owing to the fact that the segments are located in a circumferential groove or recess, the sides of which engage the ring, they are prevented from twisting or moving axially. The same arrangement is provided for each of the segments and the several segments are united at their ends with a tongue and groove joint. I have only shown one diaphragm andpacking ring but it is to be understood that they may be duplicated at will, depending upon the number of stages in the turbine. As a fur ther means of preventing in ury to the shaft and packing and also to provide for the minimum clearance between the shaft and the packing, the bore of the ring is serrated as shown in Fig. 3. That is to say, it is provided in cross-section with a series of sharp projections 12 and gr ooves or depressions 18. This arrangement of alternate projections and depressions acts as aha-filing means to prevent the free passage of steam between the ring and the shaft. Owing to the limited cross-section of metal in the teeth or projections when the shaft strikes them due to whipping or otherwise, it will merely wear away the sharpened projections Iwithout causing serious injury to the ring itself or to its holder.

I have shown the holder as being made of two parts so it and the turbine can be more readily assembled and taken down, but I do not wish to be understood as being limited to this since, under certain conditions, it may be more desirable to make the holder of a single piece. The clearance between the shaft and theprojections 12 should be as small as it is practicable to make it, the smaller the better so long as the parts will run free;

In accordance with the provisions of the patent statutes, I have described the prin ciple of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustra tive, and that the invention can be carried out by other means.

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

1. In an elastic fluid turbine, the combination. of a support having an opening through which the rotor extends, a holder also located in the opening and carried by the support, a segmental packing ring mounted in the holder, said segments having clearances between their abutting ends, and an anchor for each of the segments intermediate its ends.

2. In an elastic fluid turbine, the combination of a partition having an opening through which the rotor extends, a holder carried by the partition and located in the opening, a segmental packing ring mounted in the holder, means for anchoring each segment intermediate its ends, and other means for securing each segment which permit it to freely expand and contract.

3. In an elastic fluid turbine, the combination of a partition having an opening through which the rotor extends, a holder located in the opening and comprising a flange that is attached to the partitionand an annular recessed portion that is yieldingly connected to said flange so that it can be displaced by the-shaft, a segmental ring mounted in the recess that is sep'aratedfrom the rotor by a small clearance, slip joints between the ends of said segments,- and means for securing the segments in the holder.

4:. In an elastic fluid turbine, the combination of a partition having a central opening to receive the rotor, a holder located in the opening and comprising a flange that is attached to one side of the partition and an annular portion containing a circumferential recess, a segmental packing ring located in the recess, the bore of which ring is serrated to act as a bafiler, each of said segments being confined against axial movement by the Walls of the recess, an anchor for each of the segments, and a means for guiding and holding each segment as it THOMAS BELL. WVitnesses CHARLns V. LEHR, J. B. HENDERSON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.

It is hereloy certified that in Letters Patent No. 1,006,714, granted October 21,

1911, upon the application of Thomas Bell, of Clydebank, Scotland, for an improvement in Elastic-Fluid Turbines, an error appears in the printed specification requiring correction as follows: Page 1, line 26, the Word lead should read Zea/r, V

and that the said Letters Patent should he read With this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 12th day of December, A. D., 1911.

[SEAL] E. B. MOORE,

Umnmz'ssz'oner f Patents.

Images