SHEARING PUMP
United States Patent 3692422
A rotary shearing pump for circulating liquids containing solid substances in suspension. The pump rotor comprises a hydraulic wheel and a shearing wheel which are assembled in detachable manner and each provided with curved vanes, the vanes of the shearing wheel being joined to those of the hydraulic wheel. The vanes of the shearing wheel cooperate with at least one radial blade for grinding the solid substances and preventing clogging of the pump. The vane profiles of the hydraulic wheel are designed solely in accordance with hydrodynamic conditions. The inlet edges of the shearing-wheel vanes are located on a conical surface which is coaxial with the rotor.
US Patent References:
Construction of rotary fan or turbine wheel
Johns - August 1922 - 1427391
Centrifugal cutting pump
Durdin, Jr. - March 1945 - 2371681
/1103237.html
Williams - July 1914 - 1103237
Forage blower
West - July 1955 - 2712412
Construction of rotary fan or turbine wheel
Johns - August 1922 - 1427391
Centrifugal cutting pump
Durdin, Jr. - March 1945 - 2371681
/1103237.html
Williams - July 1914 - 1103237
Forage blower
West - July 1955 - 2712412
Application Number:
05/107069
Publication Date:
09/19/1972
Filing Date:
01/18/1971
View Patent Images:
Export Citation:
Assignee:
Etablissements, Pierre Mengin (Montargis, FR)
Primary Class:
Other Classes:
416/176, 415/218.100, 416/244R, 416/186R, 416/188
International Classes:
F04D7/04; F04D29/22; F04D7/00; F04D29/18; F04D29/02; F03B3/12; F03D9/00
Field of Search:
415/121B,121,71,213,206,219 241/46.11,197 416/183,185,186
Primary Examiner:
Raduazo, Henry F.
Claims:
What I claim is
1. A rotary shearing pump for handling liquids with entrained solids comprising:
2. A pump in accordance with claim 1, wherein the projections of the inlet edges of the shearing-wheel vanes on a plane at right angles to the rotor axis are substantially logarithmic spirals.
3. A pump in accordance with claim 2, wherein the shearing-wheel vanes have substantially helicoidal surfaces.
4. A pump in accordance with claim 1, wherein the pump body has a deflecting tongue which is disposed within the admission orifice and protects the base of the blade.
5. A pump in accordance with claim 1, wherein the pump body has a radial recess for the blade, said recess being provided with a first screw for adjusting the radial position of the blade and a second screw for lateral locking and located at right angles to the first screw.
6. A pump in accordance with claim 1, wherein the shearing wheel comprises a threaded axial portion adapted to be screwed into the hydraulic wheel, the direction of the screw-thread being opposite to the direction of rotation of the rotor and at least one tapped hole displaced off-center and intended to accommodate a threaded rod which is screwed into the hydraulic wheel.
7. A pump in accordance with claim 1, in which said blade lies in a plane that passes through said axis.
1. A rotary shearing pump for handling liquids with entrained solids comprising:
2. A pump in accordance with claim 1, wherein the projections of the inlet edges of the shearing-wheel vanes on a plane at right angles to the rotor axis are substantially logarithmic spirals.
3. A pump in accordance with claim 2, wherein the shearing-wheel vanes have substantially helicoidal surfaces.
4. A pump in accordance with claim 1, wherein the pump body has a deflecting tongue which is disposed within the admission orifice and protects the base of the blade.
5. A pump in accordance with claim 1, wherein the pump body has a radial recess for the blade, said recess being provided with a first screw for adjusting the radial position of the blade and a second screw for lateral locking and located at right angles to the first screw.
6. A pump in accordance with claim 1, wherein the shearing wheel comprises a threaded axial portion adapted to be screwed into the hydraulic wheel, the direction of the screw-thread being opposite to the direction of rotation of the rotor and at least one tapped hole displaced off-center and intended to accommodate a threaded rod which is screwed into the hydraulic wheel.
7. A pump in accordance with claim 1, in which said blade lies in a plane that passes through said axis.
Description:
This invention relates to a rotary shearing pump for circulating liquids such as sewage water which contains solid matter in suspension.
The presence of solid substances in suspension gives rise to difficulties in pumping when recourse is had to a hydraulic wheel-type pump with conventional vanes since said solid substances tend to adhere to the inlet edges of the vanes and this results sooner or later in clogging of the wheel.
It has been proposed to reduce the number of vanes and even to dispense with these vanes altogether but the hydraulic efficiency of the pump drops to low values.
In another known type of rotary pump comprising a so-called dilacerating wheel, the surface which is circumscribed about the vane inlet edges is a conical surface which is coaxial with the wheel and said edges carry out a movement of displacement in front of one or a number of stationary blades. The solid substances are conveyed by centrifugal force onto the outer edges of the vanes and then ground by the blades.
Dilacerating wheels of known types are subject to a disadvantage in that they have low hydraulic efficiency. In fact, since the vane inlet edges are necessarily arranged on a conical surface, the vanes cannot be provided with the optimum profile which would result solely from hydrodynamic considerations.
Moreover, since the blades are placed withing radial recesses of the pump body which are located in the immediate vicinity of the vane inlet edges along the greater part of said edges, substantial leakage develops along the blades between the low-pressure inlet and the high-pressure outlet of the pump.
One of the objects of the invention is to provide a pump in which the solid substances in suspension are ground while attaining high values of hydraulic efficiency.
A further object of the invention is to permit disassembly and ready replacement of those portions of the pump which serve to grind the solid matter.
Yet another object of the invention is to increase the inertia of the pump rotor in order to ensure more uniform operation in spite of impacts of solid matter at the pump inlet.
A further object of the invention is to improve the assembly and protection of the blades.
In accordance with the invention, a rotary shearing pump comprises:
A stationary pump body provided with an inlet orifice and a discharge volute,
A rotor which is symmetrical with respect to an axis of rotation and comprises a hydraulic wheel having curved vanes and a shearing wheel which is detachably connected to the hydraulic wheel and provided with curved vanes which are joined to the vanes of the hydraulic wheel,
means for driving the rotor in rotation,
at least one stationary blade disposed radially with respect to the rotor and having a cutting edge located in the immediate vicinity of the inlet edges of the shearing-wheel vanes,
said inlet edges of the shearing-wheel vanes being located on a conical surface whose axis is the axis of rotation of the rotor and the inner edge-lines of the shearing-wheel vanes being tangent to the axis of rotation of the rotor substantially at the vertex of said conical surface.
In this arrangement, the hydraulic wheel does not have any contributary function in the grinding of solid matter which is carried out solely by the shearing wheel. The vanes of the hydraulic wheel can therefore be determined solely on the basis of hydraulic conditions in order to attain maximum hydraulic efficiency.
The shearing wheel which is designed for the heaviest duty can be constructed of material which is different from that of the hydraulic wheel and can also be readily disassembled and replaced.
Leakage along the blades is minimized since these latter are entirely located within the low-pressure inlet zone of the pump.
In one preferred embodiment of the invention, the projections of the inlet edges of the shearing-wheel vanes on a plane at right angles to the axis of the rotor are substantially logarithmic spirals. The shearing-wheel vanes can have substantially cylindrical surfaces whose generating lines are parallel to the rotor axis or substantially helicoidal surfaces.
In an advantageous embodiment of the invention, the pump comprises an inertia flywheel which is mounted within the pump body on the hydraulic wheel.
Further properties and advantages of the invention will become apparent from the detailed description which is given hereinafter.
A number of embodiments of the invention are shown in the accompanying drawings which are given by way of non-limitative example, and in which:
FIG. 1 is an axial sectional view of a first embodiment of a shearing pump in accordance with the invention;
FIG. 2 is part-sectional view taken along line II--II of FIG. 1;
FIG. 3 is an end view of the rotor of the pump of FIG. 1;
FIG. 4 is an axial sectional view of the rotor of the pump of FIG. 1, the flywheel of which is assumed to have been removed;
FIGS. 5 and 6 are views respectively in plan and in axial cross-section showing a second embodiment of a rotor of a shearing pump in accordance with the invention.
The conventional representation which is universally adopted in drawings relating to rotary devices having hydraulic vanes is employed in the axial sectional views of FIGS. 1, 4 and 6 in which all the points of the vanes are accordingly assumed to have been brought back in the plane of the figure.
The rotary shearing pump which is illustrated in FIGS. 1 to 4 comprises a stationary pump body having a support bracket 1 and a volute 2 which are connected together by means of bolts 3. The support bracket 1 carries an admission duct 4 whilst the volute 2 is provided with a discharge duct 5 which can be connected to an outlet pipe 6 with interposition of a seal 7.
A rotor is mounted within the interior of the pump body and essentially consists of a hydraulic wheel 8 and a shearing wheel 9 which are joined together in a detachable manner.
The hydraulic wheel 8 comprises a hub 11 which carries short vanes 12. In the embodiment which is illustrated, the hydraulic wheel 8 is of the "closed" type or in other words comprises a flange-plate 13 which is rigidly fixed to the vanes 12 and forms together with the hub 11 passageways which are provided for the fluid to be pumped between the vanes 12.
The hub 11 of the hydraulic wheel 8 has an axial bore 14 through which passes the end of the output shaft 15 of a driving motor (not shown). The hub 11 is made fast for rotation with the shaft 15 by means of a key 16. In order to prevent longitudinal displacement, the end of the shaft 15 has a threaded portion 17 on which are screwed a nut 18 and a lock-nut 19, said nuts being fitted with a lock-washer 21. The nuts 18 and 19 serve to clamp a washer 22 which is applied against an annular shoulder of the hub 11.
The shearing wheel 9 has a hub 23 on which is formed a threaded annular flange 24, said flange being screwed into a tapped axial bore of the hydraulic wheel hub. In order to prevent slackening-off, the direction of the screw-thread is opposite to the normal direction of rotation of the rotor. Moreover, in order to prevent slackening-off in the event that the rotor were to rotate in the direction opposite to its normal direction of rotation, the hub 23 is provided in the vicinity of its periphery with two tapped holes into which are screwed threaded rods 20, said rods being also screwed into the hub of the hydraulic wheel.
Guiding of the rotor within the pump body is carried out by means of wearing rings 25, 26 which are mounted between the rotor and the support bracket 1 and volute 2 respectively. Said rings also ensure leak-tightness between the low-pressure inlet and the high-pressure outlet of the pump.
The hub 23 of the shearing wheel carries curved vanes 27 which are joined to the vanes 12 of the hydraulic wheel. Said vanes 27 have an inlet edge such as AA 1 or AA 2 (as shown in FIGS. 3 and 4), said edge being located on a conical surface which is coaxial with the axis of rotation of the rotor. In addition, the internal edge-lines such as B 1 B 2 or B 3 B 4 (shown in FIG. 4) of said vanes are tangent to the axis of the rotor in the vicinity of the vertex A of the conical surface which is circumscribed about the inlet edges.
The shearing wheel cooperates with at least one blade 28, said blade being mounted in a recess of support bracket 1 which is oriented radially with respect to the shearing wheel. The blade 28 has a cutting edge 29 which is located in immediate proximity to the inlet edges of the shearing-wheel vanes and parallel to a generating line of the cone which is circumscribed about said edges.
The radial position of the blade 28 can be adjusted by means of a screw 31 and a nut 32. After adjustment of its radial position, the blade 28 is locked by means of a transverse screw 33 and lock-nut 34 (as shown in FIG. 2). It is apparent that the pump can be fitted with a number of blades.
In order to prevent the solid matter from coming into contact with the base of the blade, the admission duct 4 is provided with a deflecting tongue 35 having a rounded profile (as shown in FIG. 1) which protects this part of the blade.
The conditions which have been set forth in the foregoing and which govern the profiles of the shearing-wheel vanes ensure that the solid substances in suspension in the liquid to be pumped are engaged by the inlet edges AA 1 , AA 2 and cut by the blade 28.
The vanes 12 of the hydraulic wheel 8 are not subject to these conditions and are designed solely on conventional hydrodynamic principles with a view to obtaining maximum hydraulic efficiency.
Two vanes are shown in the drawings but this number is clearly not limitative. In practice, the number of vanes is chosen as a function of the desired pressure head and flow rate.
The shape of the vanes 12 and 27 is established on the basis of well-known laws of hydrodynamics. A preferred design solution according to the invention consists in ensuring that the projections of the inlet edges of said vanes on a plane at right angles to the axis of the rotor are a logarithmic spiral (as shown in FIG. 3). In the particular embodiment which is shown in FIGS. 1 to 4, the vane surface is a cylindrical surface in the broadest sense of this term as used in geometry, namely a surface generated by a straight line which moves in rotation about a stationary axis while remaining parallel to itself and bearing on a curve known as the directrix. In the case under consideration, the generating line is substantially parallel to the axis of the rotor, the directrix being the logarithmic spiral of FIG. 3.
In order to take into account the particularly heavy duty which the shearing wheel is called upon to perform, said wheel is formed of an abrasion-resistant metal such as hard steel or special cast iron. By way of example, the hydraulic wheel can be formed of ordinary cast iron or of bronze.
The rotor is also provided with an inertia flywheel 36 (as shown in FIG. 1) which is secured to the hub of the hydraulic wheel by means of three screws 37. Said flywheel serves to absorb the shocks caused by the arrival of solid substances on the vanes of the shearing wheel. Furthermore, said flywheel increases the stopping time of the pump and reduces liquid-hammer within the pipes.
There is shown in FIGS. 5 and 6 another embodiment of a pump rotor which also comprises a hydraulic wheel 51 and a shearing wheel 52 (as shown in FIG. 6).
The vanes 53 of the hydraulic wheel and the vanes 54 of the shearing wheel are three in number and have a surface of the helicoid type and not a cylindrical surface as in the previous embodiment. It must be understood that the term "helicoid" is used here in its most general sense and not in the strict geometrical sense, the vane profile being dictated in each particular case by hydrodynamic conditions.
In this case, the hydraulic wheel is of the open type, the vanes 53 being supported only along their inner edge-lines by the wheel hub 55.
As in the previous embodiment, the inlet edges such as A 1 A 2 of the shearing-wheel vanes 54 are located on a circumscribed conical surface and cooperate with the cutting edge of a radial blade 56. The inner edge-lines such as B 1 B 2 of said vanes are tangent to the axis of the rotor in the vicinity of the vertex of the circumscribed conical surface.
As will be readily understood, the invention is not limited to the embodiments which have just been described. Particularly in regard to the number of vanes and the profile of the vane surface, many alternative forms of said embodiments may be contemplated without thereby departing either from the scope or the spirit of the invention.
The presence of solid substances in suspension gives rise to difficulties in pumping when recourse is had to a hydraulic wheel-type pump with conventional vanes since said solid substances tend to adhere to the inlet edges of the vanes and this results sooner or later in clogging of the wheel.
It has been proposed to reduce the number of vanes and even to dispense with these vanes altogether but the hydraulic efficiency of the pump drops to low values.
In another known type of rotary pump comprising a so-called dilacerating wheel, the surface which is circumscribed about the vane inlet edges is a conical surface which is coaxial with the wheel and said edges carry out a movement of displacement in front of one or a number of stationary blades. The solid substances are conveyed by centrifugal force onto the outer edges of the vanes and then ground by the blades.
Dilacerating wheels of known types are subject to a disadvantage in that they have low hydraulic efficiency. In fact, since the vane inlet edges are necessarily arranged on a conical surface, the vanes cannot be provided with the optimum profile which would result solely from hydrodynamic considerations.
Moreover, since the blades are placed withing radial recesses of the pump body which are located in the immediate vicinity of the vane inlet edges along the greater part of said edges, substantial leakage develops along the blades between the low-pressure inlet and the high-pressure outlet of the pump.
One of the objects of the invention is to provide a pump in which the solid substances in suspension are ground while attaining high values of hydraulic efficiency.
A further object of the invention is to permit disassembly and ready replacement of those portions of the pump which serve to grind the solid matter.
Yet another object of the invention is to increase the inertia of the pump rotor in order to ensure more uniform operation in spite of impacts of solid matter at the pump inlet.
A further object of the invention is to improve the assembly and protection of the blades.
In accordance with the invention, a rotary shearing pump comprises:
A stationary pump body provided with an inlet orifice and a discharge volute,
A rotor which is symmetrical with respect to an axis of rotation and comprises a hydraulic wheel having curved vanes and a shearing wheel which is detachably connected to the hydraulic wheel and provided with curved vanes which are joined to the vanes of the hydraulic wheel,
means for driving the rotor in rotation,
at least one stationary blade disposed radially with respect to the rotor and having a cutting edge located in the immediate vicinity of the inlet edges of the shearing-wheel vanes,
said inlet edges of the shearing-wheel vanes being located on a conical surface whose axis is the axis of rotation of the rotor and the inner edge-lines of the shearing-wheel vanes being tangent to the axis of rotation of the rotor substantially at the vertex of said conical surface.
In this arrangement, the hydraulic wheel does not have any contributary function in the grinding of solid matter which is carried out solely by the shearing wheel. The vanes of the hydraulic wheel can therefore be determined solely on the basis of hydraulic conditions in order to attain maximum hydraulic efficiency.
The shearing wheel which is designed for the heaviest duty can be constructed of material which is different from that of the hydraulic wheel and can also be readily disassembled and replaced.
Leakage along the blades is minimized since these latter are entirely located within the low-pressure inlet zone of the pump.
In one preferred embodiment of the invention, the projections of the inlet edges of the shearing-wheel vanes on a plane at right angles to the axis of the rotor are substantially logarithmic spirals. The shearing-wheel vanes can have substantially cylindrical surfaces whose generating lines are parallel to the rotor axis or substantially helicoidal surfaces.
In an advantageous embodiment of the invention, the pump comprises an inertia flywheel which is mounted within the pump body on the hydraulic wheel.
Further properties and advantages of the invention will become apparent from the detailed description which is given hereinafter.
A number of embodiments of the invention are shown in the accompanying drawings which are given by way of non-limitative example, and in which:
FIG. 1 is an axial sectional view of a first embodiment of a shearing pump in accordance with the invention;
FIG. 2 is part-sectional view taken along line II--II of FIG. 1;
FIG. 3 is an end view of the rotor of the pump of FIG. 1;
FIG. 4 is an axial sectional view of the rotor of the pump of FIG. 1, the flywheel of which is assumed to have been removed;
FIGS. 5 and 6 are views respectively in plan and in axial cross-section showing a second embodiment of a rotor of a shearing pump in accordance with the invention.
The conventional representation which is universally adopted in drawings relating to rotary devices having hydraulic vanes is employed in the axial sectional views of FIGS. 1, 4 and 6 in which all the points of the vanes are accordingly assumed to have been brought back in the plane of the figure.
The rotary shearing pump which is illustrated in FIGS. 1 to 4 comprises a stationary pump body having a support bracket 1 and a volute 2 which are connected together by means of bolts 3. The support bracket 1 carries an admission duct 4 whilst the volute 2 is provided with a discharge duct 5 which can be connected to an outlet pipe 6 with interposition of a seal 7.
A rotor is mounted within the interior of the pump body and essentially consists of a hydraulic wheel 8 and a shearing wheel 9 which are joined together in a detachable manner.
The hydraulic wheel 8 comprises a hub 11 which carries short vanes 12. In the embodiment which is illustrated, the hydraulic wheel 8 is of the "closed" type or in other words comprises a flange-plate 13 which is rigidly fixed to the vanes 12 and forms together with the hub 11 passageways which are provided for the fluid to be pumped between the vanes 12.
The hub 11 of the hydraulic wheel 8 has an axial bore 14 through which passes the end of the output shaft 15 of a driving motor (not shown). The hub 11 is made fast for rotation with the shaft 15 by means of a key 16. In order to prevent longitudinal displacement, the end of the shaft 15 has a threaded portion 17 on which are screwed a nut 18 and a lock-nut 19, said nuts being fitted with a lock-washer 21. The nuts 18 and 19 serve to clamp a washer 22 which is applied against an annular shoulder of the hub 11.
The shearing wheel 9 has a hub 23 on which is formed a threaded annular flange 24, said flange being screwed into a tapped axial bore of the hydraulic wheel hub. In order to prevent slackening-off, the direction of the screw-thread is opposite to the normal direction of rotation of the rotor. Moreover, in order to prevent slackening-off in the event that the rotor were to rotate in the direction opposite to its normal direction of rotation, the hub 23 is provided in the vicinity of its periphery with two tapped holes into which are screwed threaded rods 20, said rods being also screwed into the hub of the hydraulic wheel.
Guiding of the rotor within the pump body is carried out by means of wearing rings 25, 26 which are mounted between the rotor and the support bracket 1 and volute 2 respectively. Said rings also ensure leak-tightness between the low-pressure inlet and the high-pressure outlet of the pump.
The hub 23 of the shearing wheel carries curved vanes 27 which are joined to the vanes 12 of the hydraulic wheel. Said vanes 27 have an inlet edge such as AA 1 or AA 2 (as shown in FIGS. 3 and 4), said edge being located on a conical surface which is coaxial with the axis of rotation of the rotor. In addition, the internal edge-lines such as B 1 B 2 or B 3 B 4 (shown in FIG. 4) of said vanes are tangent to the axis of the rotor in the vicinity of the vertex A of the conical surface which is circumscribed about the inlet edges.
The shearing wheel cooperates with at least one blade 28, said blade being mounted in a recess of support bracket 1 which is oriented radially with respect to the shearing wheel. The blade 28 has a cutting edge 29 which is located in immediate proximity to the inlet edges of the shearing-wheel vanes and parallel to a generating line of the cone which is circumscribed about said edges.
The radial position of the blade 28 can be adjusted by means of a screw 31 and a nut 32. After adjustment of its radial position, the blade 28 is locked by means of a transverse screw 33 and lock-nut 34 (as shown in FIG. 2). It is apparent that the pump can be fitted with a number of blades.
In order to prevent the solid matter from coming into contact with the base of the blade, the admission duct 4 is provided with a deflecting tongue 35 having a rounded profile (as shown in FIG. 1) which protects this part of the blade.
The conditions which have been set forth in the foregoing and which govern the profiles of the shearing-wheel vanes ensure that the solid substances in suspension in the liquid to be pumped are engaged by the inlet edges AA 1 , AA 2 and cut by the blade 28.
The vanes 12 of the hydraulic wheel 8 are not subject to these conditions and are designed solely on conventional hydrodynamic principles with a view to obtaining maximum hydraulic efficiency.
Two vanes are shown in the drawings but this number is clearly not limitative. In practice, the number of vanes is chosen as a function of the desired pressure head and flow rate.
The shape of the vanes 12 and 27 is established on the basis of well-known laws of hydrodynamics. A preferred design solution according to the invention consists in ensuring that the projections of the inlet edges of said vanes on a plane at right angles to the axis of the rotor are a logarithmic spiral (as shown in FIG. 3). In the particular embodiment which is shown in FIGS. 1 to 4, the vane surface is a cylindrical surface in the broadest sense of this term as used in geometry, namely a surface generated by a straight line which moves in rotation about a stationary axis while remaining parallel to itself and bearing on a curve known as the directrix. In the case under consideration, the generating line is substantially parallel to the axis of the rotor, the directrix being the logarithmic spiral of FIG. 3.
In order to take into account the particularly heavy duty which the shearing wheel is called upon to perform, said wheel is formed of an abrasion-resistant metal such as hard steel or special cast iron. By way of example, the hydraulic wheel can be formed of ordinary cast iron or of bronze.
The rotor is also provided with an inertia flywheel 36 (as shown in FIG. 1) which is secured to the hub of the hydraulic wheel by means of three screws 37. Said flywheel serves to absorb the shocks caused by the arrival of solid substances on the vanes of the shearing wheel. Furthermore, said flywheel increases the stopping time of the pump and reduces liquid-hammer within the pipes.
There is shown in FIGS. 5 and 6 another embodiment of a pump rotor which also comprises a hydraulic wheel 51 and a shearing wheel 52 (as shown in FIG. 6).
The vanes 53 of the hydraulic wheel and the vanes 54 of the shearing wheel are three in number and have a surface of the helicoid type and not a cylindrical surface as in the previous embodiment. It must be understood that the term "helicoid" is used here in its most general sense and not in the strict geometrical sense, the vane profile being dictated in each particular case by hydrodynamic conditions.
In this case, the hydraulic wheel is of the open type, the vanes 53 being supported only along their inner edge-lines by the wheel hub 55.
As in the previous embodiment, the inlet edges such as A 1 A 2 of the shearing-wheel vanes 54 are located on a circumscribed conical surface and cooperate with the cutting edge of a radial blade 56. The inner edge-lines such as B 1 B 2 of said vanes are tangent to the axis of the rotor in the vicinity of the vertex of the circumscribed conical surface.
As will be readily understood, the invention is not limited to the embodiments which have just been described. Particularly in regard to the number of vanes and the profile of the vane surface, many alternative forms of said embodiments may be contemplated without thereby departing either from the scope or the spirit of the invention.