US 3046901 A
Description (OCR text may contain errors)
July 31, 1962 R. L. MONTGOMERY PUMP STAGE CONNECTION Filed May 26, 1961 .4 rl/lll/ll/ /ll/ I llllrlllr/l Z INVENTOR ROB RT L. MONTGOMERY CZQ WVW ATTORNEY United States Patent O 3,046,961 PUP/L STAGE (IQNNECTION Robert L. Montgomery, Windsor, Conn, assignor to United Aircratt Corporation, East Hartford, Conn, a corporation of Delaware Filed May 26, 1961, Ser. No. 112,846 2 Claims. (Cl. 10383) The present invention relates to a fluid connection between successive stages of a multistage pump.
One feature of the present invention is an arrangement by which to minimize the spacing between adjacent pump stages and at the same time provide an annular chamber into which one pump stage may discharge and from which the next stage receives fluid to be pumped. Another feature is a construction in which a common scroll provides an outlet for one pump stage and an inlet for the succeeding pump stage.
Where space is at a premium as, for example, in missiles and rockets, it is essential to have the devices such as the propellant pumps occupy a minimum of volume. One particular feature is an arrangement for a common collecting scroll between successive pump stages to eliminate the necesssity for two independent collecting chambers.
Other features and advantages will be apparent from the specification and claims, and from the accompanying drawing which illustrates an embodiment of the invention.
The single figure is a sectional view of a multistage pump.
In the arrangement shown the first-stage pump has a casing 2 which surrounds and supports successive rows of stator vanes 4. The last row of stator vanes for the pump supports at the inner ends of the vanes a housing 6 for a bearing 8, the latter being one of the bearings for the pump shaft 10. Other bearings, not shown, may be provided at other positions axially of the shaft.
The shaft 10 carries one or more rotor discs 12 on the periphery of which are mounted rotor blades 14, one row of which is located between successive rows of stator vanes 4. The rows of vanes 4 and cooperating rows of blades 14 constitute an axial flow pump which discharges fluid under pressure in an axial direction into a collecting chamber or scroll 16 immediately downstream of the last row of vanes 4. This scroll is defined between an inner curved wall 18 integral with the bearing housing 6 and an outer curved wall 20 attached as by bolts 22 to the end of the pump casing 2. The curvature of the walls '18 and 20 are 50 arranged as to define for the annular chamber 16 a cross-sectional configuration that is substantially circular as shown.
Fluid collecting in the annular chamber 16 is discharged directly into the inlet to the second stage pump. This pump includes a rotor 24 mounted on the shaft 10 and supported to rotate therewith by splines 26. A clamping sleeve 28 holds the rotor in position on the shaft and a sleeve 29 between the rotor 24 and bearing 8 spaces the first and second stage rotors on shaft 10. The outer wall 20 for the chamber 16 has an integral extension 30 which is positioned in closely spaced relation to the vanes 32 on the rotor 24 and defines a surrounding pump casing. The extension 30 terminates in an integral ring 34- which is attached as by bolts to a supporting ring 36. The extension 30 and ring 34 are connected by a curved-wall portion 38 which forms the annular chamber 40 into which the fiuid pumped by the rotor 24 is discharged.
At the outlet to the chamber 16 the outer wall 20 and inner wall 18 of the chamber are. interconnected by a row of inlet guide vanes 42 mounted on an inner ring 44 splined as at 46 to the free end of the wall 18. The outer ends of the guide vanes are interconnected by a ring "ice 6 4-8, the outer surface 5d of which is substantially cylindrical to fit .in a similarly shaped surface provided by the wall 20. These stator vanes direct the fluid from the chamber 16 into the succeeding pump stage and are preferably so positioned as to impart the desired swirl to the fluid so that the vanes 32 will operate most efiiciently at design speed.
Since the fluid being pumped flows directly from the axial fiow first-stage pump into the collecting chamber or scroll 16, and goes directly from this chamber into the succeeding pump stage which inthis case is a centrifugal pump, it is apparent that the pump stages can be relatively close together and that a single collecting chamber functions to receive the flow from the first pump stage and deliver it directly into the succeeding pump stage. Also by the arrangement of the chamber walls as described it is possible to provide ready assembly of the pump elements within the surrounding casings without a substantial disassembly of the pump construction.
The discharge from the first-stage pump into the chamber 16 is axially of the pump and the chamber is so located that, with respect to the circular cross-sectional shape of the chamber, the flow is radially of the chamber. The chamber is large enough to minimize turbulence therein and the next pump stage inlet is so located that the discharge from the chamber 16 into the pump inlet is substantially tangentially of the circular cross-sectional shape of the chamber and is also in a substantially axial direction with respect to the pumps axis.
It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.
1. A multi-stage pump having an axis and including an axial flow first stage pump and a radial flow centrifugal second stage' pump each including a bladed rotor adjacent a vaned stator and each further including inlet and outlet passages, a shaft connecting said pumps to cause the pump rotors to rotate in unison, casing means connecting said pump stages and forming said first stage pump outlet passage and said second stage pump inlet passage and so shaped that an annular collecting chamber which is substantially circular in axial cross section and several times larger than said first stage purnp outlet passage and said second stage pump inlet passage is formed therebetween and is so positioned with respect to said pumps that said first stage pump outlet passage is axial radial with respect to said collecting chamber while the inlet passage to said second stage pump is axial from said collecting chamber.
2. Apparatus according to claim 1 wherein said casing means includes an outer case which serves both to form a portion of said collecting chamber between said first and second stage pumps and a second collecting chamber downstream of said second stage pump and wherein said casing means further includes an inner case which is shaped to support a bearing for said shaft and which is also shaped to cooperate with said outer case to support outlet vanes for said first stage pump stator and inlet vanes for said second stage pump stator.
References tlited in the file of this patent FOREIGN PATENTS 672,660 Great Britain May 21, 1952 677,835 Great Britain Aug. 20, 1952 700,222 Great Britain 'Nov. 25, 1953 520,541 Canada Jan. 10, 1956 66,352 Denmark Feb, 23, 1948 106,869 Switzerland Sept. 18, 1924