US2566892A - Turbine type pump for hydraulic governing systems - Google Patents

Description

STEMS Sept. 4, 1951 s. JAcos s TURBINE TYPE PUMP FOR HYDRAULIC GOVERNING SY Filed Sept. 17, 1949 38a I W Inventor: Stephen Jacobs,

mi N His Attorny.

Patented Sept. 4, 1951 TURBINE TYPE PUMP FOR HYDRAULIC GOVERNING SYSTEMS Stephen Jacobs, Fitchburg, Mass., assignor to General Electric Company, a corporation of New York Application September 17, 1949, Serial No. 116.255

4 Claims. 1

This invention relates to improvements in the so-called turbine type pump," particularly to such a pump adapted especially for use in the hydraulic governing systems of steam turbines.

In small mechanical drive turbines, for instance those below 500 H. P. used for driving refrigerant compressors, fans, boiler feed pumps, etc., it is of the utmost importance that first cost be kept low, and the design be kept simple in order to insure reliability and facilitate maintenance when necessary. In the past, these considerations have made it seem impracticable to use. in such small comparatively inexpensive turbines, hydraulic governing systems of the types found effective on larger turbines. My earlier copending application, Serial No. 22,785, filed April 23, 1948, now Patent 2,534,974, issued December 19, 1950, disclosed a hydraulic governing system designed especially for steam turbines in this small size range. That system included a centrifugal pump driven from the turbine shaft and arranged to perform the multiple function of supplying hydraulic operating liquid for the motor which positions the turbine throttle valve, furnishing a pressure signal proportional to turbine speed for controlling the throttle valve motor, and furnishing lubricating oil to the gears, bearings, etc. The present invention is an improved type of pump for use in that turbine regulating system.

Accordingly, the object of the present invention is to provide an improved centrifugal pump of the so-called turbine type which is especially adapted to both furnish liquid for operating a hydraulic motor and lubricating the machine, and also provide the speed responsive pressure signal for controlling the hydraulic motor.

Another object is to provide a pump of the type described having a single impeller but a plurality of discharge chambers so arranged that the single pump in effect operates as if it were a plurality of separate pumps having substantially different flow characteristics.

A further object is to provide a particularly 1 effective pump for a governing system of the type described which is extremely simple and comparatively cheap to manufacture, yet reliable and readily disassembled for servicing.

Other objects and advantages will be apparent from the following description taken in connection with the accompanying drawings, in which Fig. 1 is a view in elevation of a complete pump assembly in accordance with the invention; Fig. 2 is an elevation view of the impeller by itself; and Fig. 3 is a sectional view taken on the plane 3-3 in Fig. 1 and showing the housing with the specially arranged arcuate fluid passages with their respective inlet and outlet ports.

Referring now more particularly to Fig. 1, the pump assembly proper comprises a frame or body member indicated generally at l and comprising a substantially cylindrical sleeve portion 2 having formed integral with one end thereof the radially extending flange portion 3. The sleeve portion 2 serves to support the bearings for the pump rotor shaft, while the flange portion 3 contains the members defining the pump passages with their inlets and outlets.

The turbine type impeller is shown in section at 4 in Fig. 1 and in elevation in Fig. 2. Those familiar with the centrifugal pump art will appreciate that this type of impeller comprises a disk member having on either side of the rim portion thereof a circumferentially spaced row of slots milled therein to define the radially extending blades 5. As will be apparent from the drawings, the radial length of these blades is roughly /6 the outside diameter of the rotor. The central portion of the impeller 4 defines a hub portion 6 having a central bore I adapted to freely receive the reduced end portion 8 of the rotor shaft 9. As will be apparent from Figs. 1 and 2, the hub portion Ii also defines a pair of opposed slots Ill adapted to receive the end portions of a transverse dowel pin II carried in the end portion 8 of the rotor shaft. Because of the small but significant clearance between the shaft portion 8 and the bore I, and. between the end portions of dowel II and the sides of slots ID, the impeller has a free floating or somewhat self-aligning mounting on the shaft 9.

It will be apparent from the above description and the drawings that the impeller 4 is not positioned in the axial direction by any fixed connection to the rotor shaft 9. Thus the clearance between the impeller and the casing members described hereinafter is not affected by any discrepancies in the assembly of the shaft and its bearings, nor by any differential thermal expansion which may occur due to uneven. heating of the shaft and the pump housing portion 2. The web portion of the impeller is provided with at least two pressure balancing ports to.

As will be apparent from Fig. 1, the rotor shaft 9 is carried in an anti-friction type bearing I! at the upper end of housing member 2 and a plain journal type bearing l3 at the lower end thereof. The ball bearing i2 is located in a recess I4 and may be locked in place by suitable means such as a pair of snap-rings l5, seating in annular grooves in the wall of recess II. The

extreme upper end of shaft 9 is adapted to carry a suitable gear l6, which meshes with another gear (not shown) on the turbine shaft, so that the pump impeller is driven at a speed bearing a fixed ratio to turbine shaft speed. Gear 16 may be conveniently retained by a lock nut I1.

As may also be seen in Fig. 1, the pump assembly is adapted to be contained within and supported by enclosing walls l8, which represent a portion of the turbine casing or governor housing in which the pump is used. These walls l8 preferably surround the pump in such a manner as to define the oil reservoir or sump which supplies liquid to the inlet ports of the pump. The pump housing member 2 is provided with at least one generously proportioned port 19 through which the lubricating oil has access to the lower journal bearing l3. The upper anti-friction bearing I2 is lubricated by the oil supplied to gear l6 and thrown about the housing by reason of the rapid rotation of'the gear, as described more particularly hereinafter.

As also shown in Fig. 1, the flange portion 3 of the pump assembly has a circumferential portion 3a adapted to be secured by a'row of circumferentially spaced threaded fastenings 2|! to the wall surrounding a circular opening in the bottom of the wall 18. The enclosing housing for the pump assembly is completed by a bottom cap 2|, which is also secured to the wall I8 by the threaded fastenings 20. A suitable drain plug 22 may be provided in the cap 2|, by which the operating liquid may be conveniently drained from the entire hydraulic system. i

In order to filter foreign particles from the oil flowing into the pump. a cylindrical filter screen of fine mesh wire is provided as shown at 23 in Fig. 1. The lower end portion of this cylindrical screen is adapted to engage an annular shoulder 24 formed on housing portion 3 just inside the enclosing housing l8. At the opposite end, screen 23 is supported by a disk 25 having a central opening adapted to be received by the end portion of the pump housing portion 2 and seating against a circumferential shoulder 2a.

The pumping passages with their respective inlet and outlet ports are defined by a. pair of circular plate members 26, 21 disposed at either side of the impeller 4 and located in a circular recess 28 in the fiange portion 3. These pump casing disks 26, 21 may be conveniently retained in recess 28 by a plurality of threaded fastenings one of which is shown in dotted lines at 29 in ig. 1.

As will be appreciated by those familiar with the turbine type pump, the casing disks 26, 21 are machined withextreme care so that in the assembled condition they form close clearances (on the order of .003 inch) with the sides of the impeller,

as shown at 30 in Fig. 1. The outer circumference of the lower disk member 21 defines a circumferential groove in which is disposed a resilient ring 3| of such a diameter as to be compressed into sealing engagement with the wall of the recess 28 when the disk 21 is assembled.

The pump casing disks 26, 21 are provided with arcuate grooves which cooperate to form the pumping passage shown in section at 32 in Fig. 1. It will be apparent that this annulus 32 cooperates with the walls of the slots in the impeller to form a symmetrical double opposed fiow path in which the liquid is impelled by the blades 5. Rotation of the impeller 4 causes the blades 5 to throw the liquid contained within the radial slots outwardly of oil required for other purposes.

4 into the annulus 32 whence it re-circulates to the inlet portions of the slots.

A. most important characteristic of this novel pump assembly lies in the fact that it is arranged to actually operate as a plurality of pumps combined in one. This novel result is made possible by the interesting discovery that the annulus 32 of the turbine type pump may be sub-divided circmnferentially into separate arcuate segments,

and that, if the separate segments are provided with appropriate inlet and outlet ports, each arc may act independently of the other or others, with entirely different flow characteristics being obtained from each. of special interest is the discovery that the discharge pressure generated in the respective arcuate passages isveryclosely proportional to the circumferential extent of the respective arcs. These discoveries make possible the provision of a multiple purpose pump having only a single impeller and comparatively simple enclosing members defining the pumping passages, yet capable of delivering liquid under various pressures for different purposes and with widely different flow-pressure characteristics.

In the specific application for which the invention was developed, the steam turbine requires oil under pressure for actuating the throttle valve by means of a hydraulic motor, for providing a pressure signal proportional to turbine rotor speed, and for lubrication of gears, bearings, etc. It is particularly necessary that the means for generating the speed signal pressure be unafi'ected by the operation of the hydraulic governing system or the requirements for lubricating oil, in order that the signal pressure will truly represent turbine speed regardless of variations in the flow Since maintaining an exact pressure relationship is not so essential in the case of the lubricating oil and hydraulic motor actuating liquid, the fluid for these purposes may conveniently be supplied by a common section of the pump.

The manner in which the pump casing disks 26, 21 are arranged to form the separate arcuate pumping passages may be seen by reference to Fig. 3. It will be appreciated that Fig. 3 is a bottom view of the disk 26 with the impeller 4 and lower disk 21 removed. It will be apparent from Fig. 3 that the pump annulus 32 is divided by radially extending dam portions 33, into two arcuate passages 32a, 32?). These passages are not of equal circumferential extent, but on the other hand one is on the order of while the other covers about 240. It will be noted that the direction of rotation of the impeller is counterclockwise as viewed from below. The longer passage 320. furnishes liquid for operating the hydraulic motor and for lubrication. The inlet port to this passage 32a is a drilled hole shown at 35 in Fig. 3 and in dotted lines in Fig. 1. It will be apparent that the oil in the sump defined by the walls It thus has free access through the passage 35 to one end of the arcuate passage 32a. Rapid rotation of the impeller in the counterclockwise direction causes the pressure of the liquid to progressively rise, with each recirculation through the passages defined between blades 5, until it is expelled at the other end of passage 32a by way of the discharge passage 36. As may be seen in Fig. 1, both the disks 26, 21 are provided with recesses cooperating to form this discharge passage 36. Lubricating oil for gear I 6 may be withdrawn from the passage 36 by way of a port 36a and a threaded pipe fitting 31 communicating with a pipe 38 supplying the gear lubricating nozzle aseaaaa r lie. Another port 36b in disk 21 opens from chamber 32a downwardly into the pressure liquid supply chamber 21a formed by bottom cap 1|.

One or more conduits 3! distribute oil under pressure from chamber Zla to the bearings, hydraulic throttle actuating motor and other consumers.

The shorter annulus passage 32!) is similarly supplied with oil from the sump by means of an inlet port 40 as shown in Fig. 3. This port is arranged similarly to the port 35 described above, but is not shown in Fig. 1 because it lies immediately behind the threaded fitting 31. Likewise, the outlet port for the passage 32!) consists of a recess 4| communicating with another recess in the rim of disk 26 defined by the cut-out or scallop 45. This cut-out 45 forms a communicating passage between recess II and the annular chamber 44 defined between recess 28 in flange 3 and a circumferential groove in the rim of disk It. The speed signal pressure is delivered by a conduit 43 by way of a drilled hole 42 in flange 3. It will be apparent that the signal pressure conduit can thus be located at almost any convenient point on the circumference of flange 3 by proper location of the hole 42.

It will be apparent from the above description of the structure that in operation oil is taken in from the sump defined by the housing l8 through the inlet ports 35, 40 and discharged through the passages 36a, 36b, ll to the respective consumers. While the flow requirements for lubricating the gears and bearings is substantially constant, the flow of liquid for operating the hydraulic motor is needed only intermittently, with the result that the rate of flow of oil in the pumping passage 32a is quite variable, for instance from a minimum of 2 gallons per minute to a maximum of 5 gallons per minute. On the other hand, the passage 3% is not so much a flow supplier as it is a pressure generator. That is, the only flow through the passage 32b is that required to make up any slight leakage losses occurring in the pressure responsive bellows or similar devices associated with the governing system. Ordinarily this rate of flow is extremely small.

Thus it will be seen that the flow characteristics of the two pumping passages are widely different. The importance of the present invention arises from the fact that the pressure signal generating function is in efifect completely divorced from the pressure liquid supplying function," although both are performed by a simple common pumping device. Experience in the laboratory and with machines in actual operation furnishes abundant proof that pumps in accordance with the invention are capable of effectit'ely providing the reliable speed pressure signal required by the hydraulic governing system of a steam turbine and the power liquid required for operating the turbine throttle valve and lubricating the bearings, these two functions being performed just as efficiently as if two com pletely separate pumps were employed. Thus the invention provides simple pumping mechanism for performing the variety of functions required in a small steam turbine having a hydraulic governing system and a pressure type oiling system for the bearings.

From the standpoint of ease of manufacture and accessibility for maintenance, it is to be noted that merely by removing the bottom cap 2 I, the entire pump assembly may be removed as a unit from the sump l8. Conversely, in manufacture, the complete pump unit with its bear- 6 ings, impeller, etc. may be assembled and tested separately before being installed in the sump. This is of substantial importance in view of the close clearances at 3| which must be maintained in the manufacture of this type of pump.

While the specific modification of the invention described above has included only two arcuate pumping passages 32a, 3211, it is to be noted that the invention is also applicable to a pump having three or more separate arcuate passages associated with a common impeller. It is believed that the arrangement of such pumps will be obvious from the above description. There appears to be no reason preventing the use of almost any conceivable number of separate arcuate pumping passages each supplying a separate consumer, the respective discharge pressures being proportional to the relative lengths of the pumping passages.

It will be obvious to those skilled in the art that many other changes might be made in the structure. and it is desired to cover by the appended claims all such changes and modifications as fall within the true spirit and scope of the invention.

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

1. A centrifugal pump assembly comprising an impeller of the turbine type having a circumferential row of radially extending blades and a hub portion defining a central bore with at least two diametrically opposed axial grooves communicating therewith, a rotor shaft having an end portion freely fitting the bore of the impeller and radially extending portions engaging said grooves, whereby the impeller is driven by the shaft while being free to shift axially thereon, a housing surrounding the shaft and impeller and includin a first axially extending substantially cylindrical sleeve portion coxial with the shaft, bearing means adjacent either end of said sleeve and supporting the shaft, said housing including also a radially extending flange portion spaced axially and radially from the impeller to define a circular recess, and a pair of cooperating disk members disposed in said recess at opposite sides of the impeller, said disk members defining a fluid pumping annulus surrounding the impeller blades, said disk members also including portions defining at least two circumferentially spaced dams extending radially across the pumping annulus and formin close clearances with the edges of the blades, said disk members also forming independent inlet and outlet ports communicating with the respective ends of the separate arcuate pumping chambers defined by said dams, whereby the single impeller may deliver fiuid to separate consumers having substantially different flow requirements, the discharge pressure in the separate chambers being proportional to the arcuate length of the respective chambers, said housing flange portion defining fluid inlet ports communicating with the inlet ports of the disk members, and a cylindrical filter screen member having one end portion engaging a circumferential shoulder on the housing flange member at a radius greater than that at which the inlet ports are located, the other end of the filter screen being secured to an annular disk member having a central opening adapted to surround the adjacent end of the bearing housing member and engaging a. circumferential shoulder thereon, and means seeming both of said disk members in the recess of said flange member, whereby the disk members and ascasca impeller ma be removed together from the housing and shaft respectively without disturbing the shaft and bearing assembly.

2. A centrifugal pump assembly comprising an impeller of the turbine type having a circumferential row of radial blades and a hub portion defining a central bore with at least two axial grooves communicating therewith, a rotor shaft having an end portion freely fitting the bore of the impeller and radial key portions engaging the grooves whereby the impeller is driven by the shaft while remaining free to shift axially relative thereto, a housing surrounding the shaft and impeller and including a first axially extending substantially cylindrical sleeve portion coaxial with the shaft, bearing means adjacent either end of the sleeve and supporting the shaft, the housing including also a radially extending flange portion having walls spaced axially and radially from the impeller to define a circular recess, and a pair of cooperating disk members disposed in said recess at opposite sides of the impeller and defining a fluid'pumping annulus surrounding the impeller blades, the disk members also including portionsdefining at least two circumferentially spaced dams extending radially across the pumping annulus and forming clos clearances with the edges of the blades, the arcuate length of the pumping passages defined by the dams being unequal, the disk members also having independent inlet and outlet ports communicating with the respective ends of said unequal pumping chambers, whereby the single impeller.

is capable of delivering fluid to separate consumers having substantially different flow requirements, the discharge pressures in the separate arcuate chambers being proportional to the length of the respective chambers, and mean securing both disk members in the recessof the flange member whereby the disk members and impeller may be removed together from the housing and shaft respectively without disturbing the shaft and bearing assembly.

3. A centrifugal pump assembly comprising an impeller of the turbine type with a circumferential row of radially extending blades and a hub portion defining a central bore with at least two equally spaced axial grooves communicating therewith, a rotor shaft havingan end portion freely fitting the bore of the impeller with radial key portions engaging the grooves whereby the impeller is driven by the shaft while being free to move axially thereon, a housing surrounding the shaft and impeller and including a first axially extending substantially cylindrical sleeve portion coaxial with the shaft, bearing means adjacent either end of said sleeve and supporting the shaft, the housing including also a radial-' ly extending flange portion spaced axially and radially from the impeller to define a circular recess therearound, and a pair of cooperating disk members disposed in said recess at either side of the impeller, the disk members having circumferential portions defining a fluid pumping annulus surrounding the impeller blades, the disk members also defining at least two circumferentially spaced dams extending radially across the pumping annulus and forming close clearances with the edges of the rotor blades, the disk members having independent inlet and outlet ports communicating with the respective ends of the separate arcuate pumping chambers defined by said dams, whereby the single impeller may deliver fluid to separate consumers having substantially different flow requirements and at discharge pressures proportional to the respective arcuate lengths of said pumping chambers, said housing flange portion defining fluid inlet ports communicating with the inlet ports of the disk members, and means securing both said disk members in the recess of the flange member whereby the disk members and impeller may be removed together from the housing and shaft respectively without disturbing the shaft and bearing assembly.

4. A centrifugal pump assembly comprising an impeller of the turbine type with a circumferential row of radially extending blades and a hub portion defining a central bore with at least two equally spaced axial grooves communicating therewith, a rotor shaft having an end portion freely fitting the bore of the impeller with axial key portions engaging the grooves whereby the impeller is driven by the shaft while being free to move axially thereon, a housing surrounding the shaft and impeller and including a flrst axially extending substantially cylindrical sleeve portion coaxial with the shaft, axially spaced bearing means in said sleeve supporting the shaft, the housing including also a radially extending flange portion spaced axially and radially from the impeller to define a circular recess therearound, and a pair of cooperating disk members disposed in said recess at either side of the impeller, the disk members having circumferential portions defining a fluid pumping annulus surrounding the impeller blades, said housing flange portion defining at least one inlet and one outlet port communicating with the pumping annulus, and means securing both disk members in the recess of the flange member, whereby the disk members and impeller may be removed together from the housing and shaft respectively without disturbing the shaft and bearing assembly.

STEPHEN JACOBS.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 1,861,837 Burks June 7, 1932 1,861,838 Burks June 7, 1932 1,861,839 Burks June 7, 1932 2,053,553 Burks Sept. 8, 1936 2,396,319 Edwards Mar. 12, 1946 2,426,950 Riede Sept. 2, 1947 2,504,140 Mill Apr. 18, 1950 2,534,974 Jacobs Dec. 19, 1950 FOREIGN PATENTS Number Country Date 531,254 Great Britain Jan. 1, 1941

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