U.S. patent number 3,692,426 [Application Number 05/122,353] was granted by the patent office on 1972-09-19 for fluid machines.
This patent grant is currently assigned to Weir Pumps Limited. Invention is credited to Albert Bocking, Guido Pezzani, Michael Leslie Ryall.
United States Patent |
3,692,426 |
Ryall , et al. |
September 19, 1972 |
FLUID MACHINES
Abstract
A pump including a substantially cylindrical casing in which a
radial-bladed impeller is rotatably mounted, has an axial inlet and
its outlet is arranged tangentially of the casing periphery. A
diffuser is arranged in the outlet passage, the diffuser comprising
a cylindrical recess in communication with the pump casing, a
diffusing section downstream of said recess which is divergent in
the direction of fluid flow and an intermediate section which is
convergent in the direction of fluid flow, the intermediate section
having a convex periphery.
Inventors: |
Ryall; Michael Leslie (Glascow,
SC), Pezzani; Guido (Glascow, SC), Bocking;
Albert (Glascow, SC) |
Assignee: |
Weir Pumps Limited (Glascow,
SC)
|
Family
ID: |
10056481 |
Appl.
No.: |
05/122,353 |
Filed: |
March 9, 1971 |
Foreign Application Priority Data
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Mar 31, 1970 [GB] |
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15,292/70 |
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Current U.S.
Class: |
415/207; 415/206;
415/122.1; 415/143; 415/212.1 |
Current CPC
Class: |
F04D
29/445 (20130101) |
Current International
Class: |
F04D
29/44 (20060101); F04b 029/44 (); F04b 029/40 ();
F04b 001/10 () |
Field of
Search: |
;415/204,206,213,219B,207 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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640,239 |
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Apr 1962 |
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CA |
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268,677 |
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Apr 1927 |
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GB |
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Primary Examiner: Raduazo; Henry F.
Claims
We claim:
1. A pump including a casing defining a cylindrical chamber, an
inlet passage co-axial with the axis of the chamber, a
radial-bladed impeller rotatable about the axis of the chamber, and
an outlet passage extending tangentially from the periphery of the
chamber, said outlet passage including a diffuser comprising a
substantially cylindrical passage in communication with the pump
casing, a diffusing section downstream of said cylindrical passage,
said section being divergent in the direction of fluid flow and an
intermediate section convergent in the direction of fluid flow and
having a convex periphery, the intersection of said intermediate
section and said diffusing section defining a throat, and in which
the ratio of the diameter of the cylindrical passage to the
greatest length of this passage between the chamber and the throat
is approximately 2.7 and the ratio of the diameter of the passage
to the diameter of the throat is approximately 1.5, whereby a
stable pump characteristic is obtained.
2. A pump as claimed in claim 1, in which the taper of the
diffusing section is approximately 1 in 10.
3. A pump as claimed in claim 1, in which the radius of the throat
is approximately equal to the radius of curvature of the convex
intermediate section.
Description
This invention relates generally to fluid machines and more
particularly to a pump and a diffuser for the pump, the axis of the
diffuser being arranged tangentially relative to the circle defined
by the tips of the pump impeller blades on rotation thereof.
The present invention relates to a pump including a casing defining
a cylindrical chamber, an inlet passage co-axial with the axis of
the chamber, a radial-bladed impeller rotatable about the axis of
the chamber, and an outlet passage extending tangentially from the
periphery of the chamber, such pump being referred to hereinafter
as a "pump of the type aforesaid."
According to the present invention there is provided a pump of the
type aforesaid having, for an outlet passage, a diffuser comprising
a substantially cylindrical passage in communication with the pump
casing, a diffusing section downstream of said cylindrical passage,
said section being divergent in the direction of fluid flow, and an
intermediate section convergent in the direction of fluid flow and
having a convex periphery, the intersection of said intermediate
section and said diffusing section defining a throat.
Further according to the present invention there is provided for a
pump a diffuser having a substantially cylindrical passage, a
diffusing section divergent in the direction of fluid flow and
downstream of said passage, and an intermediate section convergent
in the direction of fluid flow and having a convex periphery, the
intersection of said intermediate section and said diffusing
section defining a throat.
An embodiment of the present invention will now be described by way
of example with reference to the accompanying drawings, in
which:
FIG. 1 is a sectional perspective view of a pump;
FIG. 2 is a sectional end elevation on the plane containing line
II, II of FIG. 1; and
FIG. 3 shows a diffuser.
With reference to the drawings and initially to FIG. 1 there is
shown generally a pump 10 mounted on a step-up gear box 11 which is
supported on an end of an electric motor 12 by means of which the
pump is driven.
The pump 10 includes a casing 13 defining a cylindrical chamber 14
into which leads an inlet passage 15 for fluid to be pumped, this
passage being co-axial with the axis of the chamber 10. A fluid
outlet passage in the form of a diffuser 16 extends tangentially
from the periphery of the chamber 14 within which is housed a
radial-bladed impeller 17 carried on a shaft 18 which is co-axial
with the axis of the chamber.
With particular reference to FIGS. 2 and 3, the diffuser 16
includes a cylindrical recess 19 in the wall of the chamber 14, a
diffusing section 20 downstream of the recess 19, the section 20
being frusto-conical in shape and divergent in the direction of
fluid flow, and an intermediate section 21 which is convergent in
the direction of fluid flow and has a convex periphery. The recess
19 and the sections 20 and 21 are coaxial and the intersection of
the intermediate section 21 and the diffusing section 20 defines a
throat 22. As may be seen from FIG. 2, the intermediate section 21
is of short length compared to the section 20 and section 21 serves
to provide a smooth passage into the section 20. The diffuser is
formed in a sleeve 23 which may be detached from the pump 10.
The shaft 18 is the output shaft of the gear box 11 which is of the
overhung close-coupled type, the shaft 18 being supported in
bearings 30 and 31 located on either side of a pinion gear 32, this
gear meshing with a gear 33 on the output shaft of the motor.
The inlet passage 15 includes a sleeve 40 having a frustoconical
bore which converges towards the chamber 14. An extension 42 of the
shaft 18 projects into the passage 15 and carries an induction
impeller 43 consisting of a blade extending helically around the
extension 42. The tip diameter of the blade reduces towards the
chamber 14 so that it corresponds to the diameter of the bore of
sleeve 40.
Oil sealing of the gear box 11 is effected by a lip seal (not
shown) on the motor shaft and a mechanical seal 47 on the shaft 18.
A similar seal 48 acts as a water seal between the pump and the
gear box. Contact rings 49 are also provided on the shaft 18.
In operation fluid to be pumped is drawn through the inlet passage
15 by the induction impeller 43 which rotates with the impeller 17,
the fluid then passing into the chamber 14. Once in the chamber 14
the fluid is rotated until it reaches the periphery of the chamber
where it enters the recess 19 of the diffuser 16 and then passes
through the intermediate section 21 into the diffusing section 20
where most of the kinetic energy imparted to it is converted to
pressure energy. The diffuser 16 is so shaped that a falling
head/flow characteristic is obtained as the pump out-put increases
from zero to a predetermined level.
The head delivered by the pump may be varied by changing the
diameter of the impeller and a running clearance of one-sixteenth
inch or more between the impeller blades and the casing has been
found to give acceptable performance.
The pump is intended to operate at impeller speeds of up to 18,000
r.p.m. and the induction means is provided to inhibit cavitation at
such speeds with low-pressure incoming fluid.
The dimensions of the pump described in the embodiment are as
follows:
Radius of cylindrical chamber 2.625 in. Diameter of cylindrical
recess 0.75 in. Diameter of throat 0.5 in. Radius of convex
curvature of peri- phery of intermediate section 2,875 in. Length
of diffusing section 2.875 in. Taper of diffusing section 1 in
10
Because of the falling head/flow characteristic achieved by
diffusers according to the invention pumps may be readily connected
in parallel or be used in conjunction with a regulating valve such
as is fitted to boilers.
Pumps as described above are intended for use in boiler feed
applications and mobile and fixed cleaning installations such as an
automatic car wash and other general pumping duties.
* * * * *