Title of Invention	A PUMP FOR PUMPING CONTAMINATED LIQUID AND SOLID MATTER
Abstract	The invention relates to a pump for pumping contaminated liquid including solid matter, comprising a pump housing provided with a rotatable impeller suspended in a drive shaft and having at least one vane, and an impeller seat, at least one part of the impeller and the impeller seat being movable in the axial direction in relation to each other. Furthermore, the impeller seat presents at least one groove in the top surface thereof.

Title of Invention

A PUMP FOR PUMPING CONTAMINATED LIQUID AND SOLID MATTER

Abstract

The invention relates to a pump for pumping contaminated liquid including solid matter, comprising a pump housing provided with a rotatable impeller suspended in a drive shaft and having at least one vane, and an impeller seat, at least one part of the impeller and the impeller seat being movable in the axial direction in relation to each other. Furthermore, the impeller seat presents at least one groove in the top surface thereof.

Full Text	1 A PUMP Technical field of the Invention The present invention relates generally to the field of pumps for sewage or waste water, and more specifically to a pump for pumping unscreened contaminated liquid including solid matter, such as plastic materials, hygiene articles, textile, rags, etc. Said pump comprises a pump housing provided with a rotatable impeller suspended in a drive shaft and having at least one vane, and an impeller seat, at least one part of the impeller and the impeller seat being movable in the axial direction in relation to each other. Background of the Invention In sewage stations, septic tanks, wells, etc., it often occur that solid matter or pollutants, such as socks, sanitary pads, paper, etc., clogs the submersible pump that is lowered into the basin of the system. The contaminations are sometimes too big to pass through the pump if the impeller and the impeller seat are located at a fixed distance from each other. In order to get rid of the clogging matter, it is known to equip centrifugal pumps with means for cutting up the solid matter into smaller pieces and thereafter evacuate the small pieces together with the pumped liquid. However, the cutting up of the solid matter is energy intensive, which is adverse especially since pumps of this kind usually operates for long periods of time. Another conventional way of getting rid of clogging matter is to use an impeller having only one vane, which present one large throughput channel capable of letting through the solid matter. One drawback with this type of pump is that the solid matter often get tangled around the leading edge of the vane. A third attempt, to solved the problem of large solid matter clogging the pump, use a arrangement in 2 which the impeller is at a fixed distance from the impeller seat, e.g. 30-40 mm. A huge drawback is that the pump has a really low efficiency all the time. A better way of solving the problem of solid matter clogging the pump should be to admit the impeller and the impeller seat to be movable in the axial direction in relation to each other, in order to form a gap. But known pumps comprising this feature uses said gap for other purposes. Furthermore, they only admit a small gap between the impeller and the impeller seat. In EP 1,247,990 is shown a pump, the impeller of which is movable in the axial direction in relation to the impeller seat along the longi- tudinal direction of the drive shaft. But the movability is strongly limited and the object solved is only to admit operational start in a dry state, e.g. now liquid in the pump. GB 751,908 shows a pump having a manually controlled movability of the impeller in relation to the impeller seat. The object of this construction is to admit a regulation of the efficiency of the pump. US 6,551,058 shows a pump having an impeller which is movable in the axial direction in relation to the drive shaft. The object of the shown construction is to avoid the vanes of the impeller to be damaged if solid matter enters the pump. More precisely, none of the abovementioned, or other, documents present a solution, or an object, usable for letting through large pieces of solid matter. Even though small pieces of solid matter might pass through the gap that is formed between the lower edge of the impeller and the impeller seat, it is more likely that large pieces of solid matter will get stuck in the narrow gap formed. In a worst case scenario, the impeller might get totally jammed and thus seriously damage the pump. Such an unintentional shutdown is costly, due to expensive, cumbersome and unplanned maintenance work. It is even better if the solid matter blocks the inlet of the pump than the solid matter gets jammed between the vane of the 3 impeller and the impeller seat. If the inlet is blocked the only effect is that less fluid will get pumped through the pump, but if the impeller is jammed the pump might get damaged. A closely related patent, EP 1,357,294 directed to the applicant, shows a pump which is exposed for solid matter included in unscreened sewage water. The pump has a groove in the top surface of the impeller seat for transportation of the entire contaminating subject towards the periphery of the pump housing. However, it is strictly described that the impeller shall not be movable in relation to the impeller seat, due to the object of scraping of solid matter from the vane against the edge of the groove. Furthermore, submergible pumps are used to pump fluid from basins that are hard to get access to for maintenance and the pumps often operate for long periods of time, not infrequently up to 12 hours a day or more. Therefore it is highly desirable to provide a pump having long durability. Summary of the Invention The present invention aims at obviating the afore- mentioned disadvantages of previously known pumps, and at providing an improved pump. A primary object of the present invention is to provide an improved pump of the initially defined type, which in a reliable way admits large solid matter to pass through the pump, without having to cut up the solid matter into smaller pieces. It is another object of the present invention to provide a pump with respect to the reduce friction between the impeller and the drive shaft in the axial direction, in order to get a better movability of the impeller. It is yet another object of the present invention to provide a pump having an improved durability, thanks to a reduced friction in the interface 4 between the impeller and the drive shaft, and by that a more reliable control of the impeller during movement. According to the invention at least the primary object is attained by means of the initially defined pump having the features defined in the independent claim. Preferred embodiments of the present invention are further defined in the dependent claims. According to the present invention, there is pro- vided a pump of the initially defined type, which is characterized in that the impeller seat presents at least one groove in the top surface thereof. Thus, the present invention is based on the insight of the importance that a movability of the impeller in the axial direction a distance too short in relation to the size of the solid matter brings about other and even worse problems than preventing the fluid to be pumped. More precisely, it is important to undoubtedly remove solid matter from the gap between the vane of the impeller and the impeller seat. In a preferred embodiment of the present invention, the groove extends in a spiral shape from a centrally located open channel in the impeller seat to the periphery thereof, along the direction of rotation of the impeller. This means that if the leading edge of the vane of the impeller hit a piece of solid matter, the solid matter will get forced outwards towards the impeller seat as a consequence of the centrifugal force and that the leading edge of the vane is back swept. When the solid matter meets the groove in the top surface of the impeller seat it will follow the shape of the groove outwards and at the same time lift the impeller from the impeller seat, and thus quickly be passed through the pump. According to a preferred embodiment, the impeller may be moved a great distance from the impeller seat, preferably as much as the diameter of the open channel of 5 the impeller seat. Then the ability to pass solid matter through the pump is considerably increased. Brief description of the drawings A more complete understanding of the abovementioned and other features and advantages of the present invention will be apparent from the following detailed description of preferred embodiments in conjunction with the appended drawings, wherein: Fig. 1 is a cross sectional view of the impeller and the impeller seat, the impeller being in a first, lower position, Fig. 2 is a cross sectional view of the impeller and the impeller seat, the impeller being in a second, upper position, Fig. 3 is an enlarged cross sectional view of one embodiment of the joint between the impeller and the drive shaft, the impeller being removed, Fig. 4 is a cross sectional view from above of the joint in fig 3, Fig. 5 is a perspective view from below of the impeller, Fig. 6 is a perspective view from above of the impeller seat, Fig. 7 is a cross sectional view of the impeller and the impeller seat, having an alternative joint, and Fig. 8 is a cross sectional view from above of the joint in fig 7. Detailed description of preferred embodiments of the invention Figs 1 and 2 show an impeller 1 and an impeller seat 2, usually accommodated in a pump housing of a pump (not shown). The other parts of the pump are removed for the sake of simplicity of reading the figures. The invention relates to pumps in general, but in the preferred 6 embodiment the pump is constituted by a submergible centrifugal pump. In a preferred embodiment of the present invention the impeller seat 2 is constituted by an insert releasably connected to the pump housing by being located in a seat in the pump housing in such a way that the insert cannot rotate relative to the pump housing. The impeller 1 is suspended in a drive shaft 3 extending from above, and is rotatable in the pump housing. The first, upper end (not shown) of the drive shaft 3 is connected to the engine of the pump. The second, lower end of the drive shaft 3 is connected to the impeller 1 by means of a joint in such a way that the impeller 1 is movable in the axial direction along the drive shaft 3, but rotates jointly with the drive shaft 3. Preferably the drive shaft 3 is inserted in a centrally located hub 4 of the impeller 1. Reference is now also made to figs 5 and 6. The impeller 1 comprises at least one vane 5 extending from the hub 4 towards the periphery of the impeller 1, preferably in a spiral shape. The direction of rotation of the impeller 1 is clockwise in the shown embodiments, and the vanes 5 are extending in the opposite direction, i.e. counter clockwise. In the shown embodiment the impeller 1 has two vanes 5, each having an extension running approximately 270 degrees around the hub 4, but it shall be pointed out that the number of vanes 5 and the length of the vanes 5 may vary greatly, in order to suit different liquids and applications. For example, each vane may extend in a straight line radially outwards from the hub. Each vane 5 comprises a leading edge 6 and a lower edge or tip surface 7. The leading edge 6 is located directly above a centrally located open channel 8 of the impeller seat 2 and the lower edge 7 of the vane 5 is located above a top surface 9 of the impeller seat 2. 7 In the top surface 9 of the impeller seat 2 and contiguous to the open channel 8 of the impeller seat 2, is provided at least one groove or relief groove 10. The groove 10 extends from the open channel 8 of the impeller seat 2 towards the periphery thereof. Preferably in a spiral shape that sweeps outwards in the direction of rotation of the impeller 1, i.e. in an opposite direction to the one of the vanes 5. The number of grooves 10 and their shape and orientation may vary greatly, in order to suit different liquids and applications. The function of the groove 10 is to guide the solid matter outwards to the periphery of the pump housing. As the solid matter passes through the pump, some will fasten underneath the vanes 5 of the impeller 1 and slow down the rotating motion of the impeller 1 and even stop the same. But the groove 10 contribute to keep the vanes 5 clean, by scraping of the solid matter each time the vane 5 passes the same. If the solid matter is to big to fit in the groove 10, between the impeller 1 and the impeller seat 2, the impeller 1 will be moved upwards away from the impeller seat 2 by the solid matter and thereby admitting the solid matter to pass through the pump. The shape of the lower edge 7 of the vane 5 corre- sponds, in the axial direction, to the shape of the top surface 9 of the impeller seat 2. The axial distance between the lower edge 7 and the top surface 9 ought to be less than 1 mm when the impeller 1 is in the first, lower position shown in fig 1. Preferably said distance is less than 0,7 mm and most preferably less than 0,5 mm. At the same time said distance shall be more than 0,1 mm and preferably more than 0,3 mm. If the impeller 1 and the impeller seat 2 are to close to each other a frictional force or a breaking force acts on the vanes 5 of the impeller 1. In order to ensure that the open channel 8 does not get clogged, the impeller seat 2 is preferably provided 8 with means for guiding the solid matter towards the groove 10. The guiding means comprises at least one guide pin 11 extending from the top surface 9 of the impeller seat 2, more precisely from the part of the top surface 9 facing the open channel 8. The guide pin 11 extends generally in the radial direction of the impeller seat 2 and is located below the impeller 1 and presents an upper edge 12, which extends from a position contiguous to the most inner part of the vane 5 of the impeller 1 to the top surface 8 of the impeller seat 2. More precisely, the most inner part of the upper edge 12 of the guide pin 11 is located at approximately the same radial distance from the center of the impeller 1 as the most inner part of the vane 5 of the impeller 1. Preferably the upper edge 12 of the guide pin 11 terminates adjacent to the "inlet" of said groove 10. The axial distance between the upper edge 12 of the guide pin 11 and the leading edge 6 of the vane 5 ought to be less than 1 mm, when the impeller 1 is in the first, lower position. Furthermore, the upper edge 12 of the guide pin 11 corresponds to and is located adjacent to the leading edge 6 of the vane 5 of the impeller 1. The axial movability between the impeller 1 and the impeller seat 2 should be any appropriate length depending on the application, i.e. from 0 mm and upwards. Preferably said movability should be at least 15 mm, more preferably at least 40 mm, and most preferably at least as much as the diameter of the open channel 8. In the shown embodiment the diameter of the open channel 8 is 150 mm. Furthermore, the axial movability may be achieved in a lot of ways but in a preferred embodiment of the present invention the impeller 1 is movable along the axial direction of the drive shaft 3. Reference is now made to figs 3 and 4. In fig 3 is shown a joint of the pump admitting axial movability of the impeller 1 in relation to the drive shaft 3, at the same time as the drive shaft 3 transmits a turning motion to the 9 impeller 1. The joint comprises a socket 13 provided in the central hub 4 of the impeller 1, and connected to the impeller 1 by means of bolts (not shown), or the like. Alternatively the socket 13 may be integrated with the impeller 1. The socket 13 presents a cavity 14 in a central part thereof, which cavity 14 accommodate the second, lower end of the drive shaft 3. In the preferred embodiment of the present invention the drive shaft 3 is provided with a sleeve 15 at the second, lower end thereof, the sleeve 15 being connected to the drive shaft 3 by means of a bolt 16 and/or key and keyway, or the like. Alternatively the sleeve 15 may be integrated with the drive shaft 3. The sleeve 15 has a first, upper part having a first external diameter, which is essentially equal to the internal diameter of a flange 17 of the socket 13. Further- more, the sleeve 15 has a second, lower part having a dia- meter larger than said first diameter of the sleeve 15. The diameter of the second part of the sleeve 15 is essentially equal to the internal diameter of the cavity 14. Due to these dimensional relationships the impeller 1 is suspended in the drive shaft 3. The cavity 14 presents a larger extension in the axial direction than the second part of the sleeve 15, the socket 13 and the impeller 1 being movable a distance essentially equal to that difference. In a first embodiment of the invention the joint comprises at least one discrete element 18 arranged at the interface between the socket 13 or impeller 1 and the sleeve 15 or the drive shaft 3. The element 18 imperatively transmits a turning motion from the drive shaft 3 to the impeller 1 and admits the impeller 1 to move along the drive shaft 3. The socket 13 is provided with a recess 19 for each element 18, the recess 19 extending in the axial direction of the drive shaft 3. In the sleeve 15, opposite to the recess 19 of the socket 13, is formed an interacting recess 20, which together with the recess 19 of the socket 13 accommodate said element 18. In fig 3 the right element 10 18 is removed in order to get a general view of the recesses 19, 20. In fig 4 the left and right element 18 are removed. Preferably only two elements 18 are used and the dimensions of the elements 18 are determined by the torque being transmitted from the drive shaft 3 to the impeller 1. In the shown embodiment in figs 1-4 the discrete element is constituted by a bar, preferably a circular bar, due to a manufacturing point of view. It shall be pointed out that in an alternative embodiment the discrete element 18 can be constituted by a number of balls following the recess 19 of the sleeve 15 as the impeller 1 moves in the axial direction. More precisely, the recess 19 of the sleeve 15 has upper and lower obstructions that prevent the balls from escaping into the cavity 14. Alternatively, the discrete element 18 may be integrated with the inner surface of the sleeve 15, i.e. ridges on the inner surface extending into the recesses 19 of the socket 13. The relative movability of the impeller 1 along the drive shaft 3 may alternatively be realized by means of a spline joint between the impeller 1 and the drive shaft 3, shown in figs 7 and 8. One advantage of using a spline joint is that the joint will comprise fewer elements. The impeller 1 is, in a preferred embodiment of the present invention, freely movable along the drive shaft 3 since there are no springs or the like obstructing the movement. More precisely, any force from a solid matter on the impeller 1 from underneath that overcomes the high pressure on the top side of the impeller 1 will manage to raise the impeller 1 from the impeller seat 2. When the solid matter is removed the impeller 1 automatically will return to the lower position according to fig 1 since the pressure on the top side of the impeller 1 is higher than the pressure on the bottom side of the impeller 1. Alternatively, the impeller 1 may, when the pump is about to be started, be biased to the upper position 11 according to fig 2 by means of a spring. Not until the pump is started and the liquid starts to flow the impeller 1 will move towards the impeller seat 2. This will prevent the impeller 1 from shaking inside the pump housing during transportation. In addition, the starting torque for the impeller 1 is lowered since the impeller 1 and the impeller seat 2 are well distanced from each other. If a large piece of solid matter enters the open channel 8 of the impeller seat 2, it is too large to get in-between the vane 5 of the impeller 1 and the top surface 9 of the impeller seat 2. But the groove 10 in conjunction with the vane 5 of the impeller 1 grabs hold of the solid matter and forces it to "climb" over the top surface 9 of the impeller seat 2 along the groove 10. Finally, it shall be pointed out that the most preferred number of grooves 10 is one. Furthermore, the pump shall preferably comprise one guide pin 11. Otherwise the open channel 8 should be too obstructed, which would adversely affect the function of the pump. Feasible modifications of the Invention The invention is not limited only to the embodi- ments described above and shown in the drawings. Thus, the pump, or more precisely the impeller seat may be modified in all kinds of ways within the scope of the appended claims. It shall be pointed out that instead of the impeller being movable along the drive shaft the axial movability may be achieved in a lot of ways, e.g. both the drive shaft and the impeller may be movable away from the impeller seat, or the impeller seat may be movable away from the impeller, or both the impeller and the impeller seat may be movable away from each other. In addition, only the vanes may be movable in the axial direction in relation to the hub of the impeller. For example, each vane is individually movable and runs in a groove on the outside of 12 the hub, thereby at least one part of the vane is movable in the axial direction in relation to the impeller seat. 13 Claims 1. A pump for pumping contaminated liquid including solid matter, comprising a pump housing provided with a rotatable impeller (1) suspended in a drive shaft (3) and having at least one vane (5), and an impeller seat (2), at least one part of the impeller (1) and the impeller seat (2), during operation of the pump, being movable in the axial direction in relation to each other, characterized in that the impeller seat (2) presents at least one groove (10) in the top surface (9) thereof. 2. A pump according to claim 1, wherein the impeller (1) is movable at least 15 mm from the impeller seat (2). 3. A pump according to claim 1 or 2, wherein the impeller (1) is movable at least 40 mm from the impeller seat (2). 4. A pump according to any of the claim 1-3, wherein the groove (10) extends from a centrally located open channel (8) in the impeller seat (2) to the periphery thereof. 5. A pump according to any of the claims 1-4, wherein the groove (10) extends in a spiral shape, from the open channel (8) and outwards along the direction of rotation of the impeller (1). 6. A pump according to claim 5, wherein the vane (5) of the impeller (1) extends in a spiral shape in the opposite direction to the spiral shape of the groove (10). 7. A pump according to any of the preceding claims, wherein the impeller (1) is freely movable in the axial direction in relation to the drive shaft (3). 14 8. A pump according to claim any of the preceding claims, wherein the pump comprises at least one discrete element (18) arranged at an interface between the impeller (1) and the drive shaft (3). 9. A pump according to claim 8, wherein the impeller (1) and the drive shaft (3) presents recesses (19, 20) in the opposite surfaces at said interface, which recesses (19, 20) jointly accommodate said element (18). 10. A pump according to claim 8 or 9, wherein the interface accommodate at least two discrete elements (18), which are equidistant separated from each other along the circumference of the drive shaft. 11. A pump according to any of the claims 8-10, wherein each element (18) comprises a bar extending in the longitudinal direction of the drive shaft (3). 12. A pump according to any of the preceding claims, wherein a guide pin (11) extends from the impeller seat (9) towards the center of the impeller (1) and is located adjacent to said groove (10). The invention relates to a pump for pumping contaminated liquid including solid matter, comprising a pump housing provided with a rotatable impeller suspended in a drive shaft and having at least one vane, and an impeller seat, at least one part of the impeller and the impeller seat being movable in the axial direction in relation to each other. Furthermore, the impeller seat presents at least one groove in the top surface thereof.

Full Text

1
A PUMP
Technical field of the Invention
The present invention relates generally to the
field of pumps for sewage or waste water, and more
specifically to a pump for pumping unscreened contaminated
liquid including solid matter, such as plastic materials,
hygiene articles, textile, rags, etc. Said pump comprises a
pump housing provided with a rotatable impeller suspended
in a drive shaft and having at least one vane, and an
impeller seat, at least one part of the impeller and the
impeller seat being movable in the axial direction in
relation to each other.
Background of the Invention
In sewage stations, septic tanks, wells, etc., it
often occur that solid matter or pollutants, such as socks,
sanitary pads, paper, etc., clogs the submersible pump that
is lowered into the basin of the system. The contaminations
are sometimes too big to pass through the pump if the
impeller and the impeller seat are located at a fixed
distance from each other.
In order to get rid of the clogging matter, it is
known to equip centrifugal pumps with means for cutting up
the solid matter into smaller pieces and thereafter
evacuate the small pieces together with the pumped liquid.
However, the cutting up of the solid matter is energy
intensive, which is adverse especially since pumps of this
kind usually operates for long periods of time. Another
conventional way of getting rid of clogging matter is to
use an impeller having only one vane, which present one
large throughput channel capable of letting through the
solid matter. One drawback with this type of pump is that
the solid matter often get tangled around the leading edge
of the vane. A third attempt, to solved the problem of
large solid matter clogging the pump, use a arrangement in

2
which the impeller is at a fixed distance from the impeller
seat, e.g. 30-40 mm. A huge drawback is that the pump has a
really low efficiency all the time.
A better way of solving the problem of solid
matter clogging the pump should be to admit the impeller
and the impeller seat to be movable in the axial direction
in relation to each other, in order to form a gap. But
known pumps comprising this feature uses said gap for other
purposes. Furthermore, they only admit a small gap between
the impeller and the impeller seat. In EP 1,247,990 is
shown a pump, the impeller of which is movable in the axial
direction in relation to the impeller seat along the longi-
tudinal direction of the drive shaft. But the movability is
strongly limited and the object solved is only to admit
operational start in a dry state, e.g. now liquid in the
pump. GB 751,908 shows a pump having a manually controlled
movability of the impeller in relation to the impeller
seat. The object of this construction is to admit a
regulation of the efficiency of the pump. US 6,551,058
shows a pump having an impeller which is movable in the
axial direction in relation to the drive shaft. The object
of the shown construction is to avoid the vanes of the
impeller to be damaged if solid matter enters the pump.
More precisely, none of the abovementioned, or
other, documents present a solution, or an object, usable
for letting through large pieces of solid matter. Even
though small pieces of solid matter might pass through the
gap that is formed between the lower edge of the impeller
and the impeller seat, it is more likely that large pieces
of solid matter will get stuck in the narrow gap formed. In
a worst case scenario, the impeller might get totally
jammed and thus seriously damage the pump. Such an
unintentional shutdown is costly, due to expensive,
cumbersome and unplanned maintenance work. It is even
better if the solid matter blocks the inlet of the pump
than the solid matter gets jammed between the vane of the

3
impeller and the impeller seat. If the inlet is blocked the
only effect is that less fluid will get pumped through the
pump, but if the impeller is jammed the pump might get
damaged.
A closely related patent, EP 1,357,294 directed to
the applicant, shows a pump which is exposed for solid
matter included in unscreened sewage water. The pump has a
groove in the top surface of the impeller seat for
transportation of the entire contaminating subject towards
the periphery of the pump housing. However, it is strictly
described that the impeller shall not be movable in
relation to the impeller seat, due to the object of
scraping of solid matter from the vane against the edge of
the groove.
Furthermore, submergible pumps are used to pump
fluid from basins that are hard to get access to for
maintenance and the pumps often operate for long periods of
time, not infrequently up to 12 hours a day or more.
Therefore it is highly desirable to provide a pump having
long durability.
Summary of the Invention
The present invention aims at obviating the afore-
mentioned disadvantages of previously known pumps, and at
providing an improved pump. A primary object of the present
invention is to provide an improved pump of the initially
defined type, which in a reliable way admits large solid
matter to pass through the pump, without having to cut up
the solid matter into smaller pieces. It is another object
of the present invention to provide a pump with respect to
the reduce friction between the impeller and the drive
shaft in the axial direction, in order to get a better
movability of the impeller. It is yet another object of the
present invention to provide a pump having an improved
durability, thanks to a reduced friction in the interface

4
between the impeller and the drive shaft, and by that a
more reliable control of the impeller during movement.
According to the invention at least the primary
object is attained by means of the initially defined pump
having the features defined in the independent claim.
Preferred embodiments of the present invention are further
defined in the dependent claims.
According to the present invention, there is pro-
vided a pump of the initially defined type, which is
characterized in that the impeller seat presents at least
one groove in the top surface thereof.
Thus, the present invention is based on the
insight of the importance that a movability of the impeller
in the axial direction a distance too short in relation to
the size of the solid matter brings about other and even
worse problems than preventing the fluid to be pumped. More
precisely, it is important to undoubtedly remove solid
matter from the gap between the vane of the impeller and
the impeller seat.
In a preferred embodiment of the present
invention, the groove extends in a spiral shape from a
centrally located open channel in the impeller seat to the
periphery thereof, along the direction of rotation of the
impeller. This means that if the leading edge of the vane
of the impeller hit a piece of solid matter, the solid
matter will get forced outwards towards the impeller seat
as a consequence of the centrifugal force and that the
leading edge of the vane is back swept. When the solid
matter meets the groove in the top surface of the impeller
seat it will follow the shape of the groove outwards and at
the same time lift the impeller from the impeller seat, and
thus quickly be passed through the pump.
According to a preferred embodiment, the impeller
may be moved a great distance from the impeller seat,
preferably as much as the diameter of the open channel of

5
the impeller seat. Then the ability to pass solid matter
through the pump is considerably increased.
Brief description of the drawings
A more complete understanding of the
abovementioned and other features and advantages of the
present invention will be apparent from the following
detailed description of preferred embodiments in
conjunction with the appended drawings, wherein:
Fig. 1 is a cross sectional view of the impeller and the
impeller seat, the impeller being in a first, lower
position,
Fig. 2 is a cross sectional view of the impeller and the
impeller seat, the impeller being in a second, upper
position,
Fig. 3 is an enlarged cross sectional view of one
embodiment of the joint between the impeller and the
drive shaft, the impeller being removed,
Fig. 4 is a cross sectional view from above of the joint in
fig 3,
Fig. 5 is a perspective view from below of the impeller,
Fig. 6 is a perspective view from above of the impeller
seat,
Fig. 7 is a cross sectional view of the impeller and the
impeller seat, having an alternative joint, and
Fig. 8 is a cross sectional view from above of the joint in
fig 7.
Detailed description of preferred embodiments of the
invention
Figs 1 and 2 show an impeller 1 and an impeller
seat 2, usually accommodated in a pump housing of a pump
(not shown). The other parts of the pump are removed for
the sake of simplicity of reading the figures. The
invention relates to pumps in general, but in the preferred

6
embodiment the pump is constituted by a submergible
centrifugal pump.
In a preferred embodiment of the present invention
the impeller seat 2 is constituted by an insert releasably
connected to the pump housing by being located in a seat in
the pump housing in such a way that the insert cannot
rotate relative to the pump housing. The impeller 1 is
suspended in a drive shaft 3 extending from above, and is
rotatable in the pump housing. The first, upper end (not
shown) of the drive shaft 3 is connected to the engine of
the pump. The second, lower end of the drive shaft 3 is
connected to the impeller 1 by means of a joint in such a
way that the impeller 1 is movable in the axial direction
along the drive shaft 3, but rotates jointly with the drive
shaft 3. Preferably the drive shaft 3 is inserted in a
centrally located hub 4 of the impeller 1.
Reference is now also made to figs 5 and 6. The
impeller 1 comprises at least one vane 5 extending from the
hub 4 towards the periphery of the impeller 1, preferably
in a spiral shape.
The direction of rotation of the impeller 1 is
clockwise in the shown embodiments, and the vanes 5 are
extending in the opposite direction, i.e. counter
clockwise. In the shown embodiment the impeller 1 has two
vanes 5, each having an extension running approximately 270
degrees around the hub 4, but it shall be pointed out that
the number of vanes 5 and the length of the vanes 5 may
vary greatly, in order to suit different liquids and
applications. For example, each vane may extend in a
straight line radially outwards from the hub. Each vane 5
comprises a leading edge 6 and a lower edge or tip surface
7. The leading edge 6 is located directly above a centrally
located open channel 8 of the impeller seat 2 and the lower
edge 7 of the vane 5 is located above a top surface 9 of
the impeller seat 2.

7
In the top surface 9 of the impeller seat 2 and
contiguous to the open channel 8 of the impeller seat 2, is
provided at least one groove or relief groove 10. The
groove 10 extends from the open channel 8 of the impeller
seat 2 towards the periphery thereof. Preferably in a
spiral shape that sweeps outwards in the direction of
rotation of the impeller 1, i.e. in an opposite direction
to the one of the vanes 5. The number of grooves 10 and
their shape and orientation may vary greatly, in order to
suit different liquids and applications. The function of
the groove 10 is to guide the solid matter outwards to the
periphery of the pump housing. As the solid matter passes
through the pump, some will fasten underneath the vanes 5
of the impeller 1 and slow down the rotating motion of the
impeller 1 and even stop the same. But the groove 10
contribute to keep the vanes 5 clean, by scraping of the
solid matter each time the vane 5 passes the same. If the
solid matter is to big to fit in the groove 10, between the
impeller 1 and the impeller seat 2, the impeller 1 will be
moved upwards away from the impeller seat 2 by the solid
matter and thereby admitting the solid matter to pass
through the pump.
The shape of the lower edge 7 of the vane 5 corre-
sponds, in the axial direction, to the shape of the top
surface 9 of the impeller seat 2. The axial distance
between the lower edge 7 and the top surface 9 ought to be
less than 1 mm when the impeller 1 is in the first, lower
position shown in fig 1. Preferably said distance is less
than 0,7 mm and most preferably less than 0,5 mm. At the
same time said distance shall be more than 0,1 mm and
preferably more than 0,3 mm. If the impeller 1 and the
impeller seat 2 are to close to each other a frictional
force or a breaking force acts on the vanes 5 of the
impeller 1.
In order to ensure that the open channel 8 does
not get clogged, the impeller seat 2 is preferably provided

8
with means for guiding the solid matter towards the groove
10. The guiding means comprises at least one guide pin 11
extending from the top surface 9 of the impeller seat 2,
more precisely from the part of the top surface 9 facing
the open channel 8. The guide pin 11 extends generally in
the radial direction of the impeller seat 2 and is located
below the impeller 1 and presents an upper edge 12, which
extends from a position contiguous to the most inner part
of the vane 5 of the impeller 1 to the top surface 8 of the
impeller seat 2. More precisely, the most inner part of the
upper edge 12 of the guide pin 11 is located at
approximately the same radial distance from the center of
the impeller 1 as the most inner part of the vane 5 of the
impeller 1. Preferably the upper edge 12 of the guide pin
11 terminates adjacent to the "inlet" of said groove 10.
The axial distance between the upper edge 12 of the guide
pin 11 and the leading edge 6 of the vane 5 ought to be
less than 1 mm, when the impeller 1 is in the first, lower
position. Furthermore, the upper edge 12 of the guide pin
11 corresponds to and is located adjacent to the leading
edge 6 of the vane 5 of the impeller 1.
The axial movability between the impeller 1 and
the impeller seat 2 should be any appropriate length
depending on the application, i.e. from 0 mm and upwards.
Preferably said movability should be at least 15 mm, more
preferably at least 40 mm, and most preferably at least as
much as the diameter of the open channel 8. In the shown
embodiment the diameter of the open channel 8 is 150 mm.
Furthermore, the axial movability may be achieved in a lot
of ways but in a preferred embodiment of the present
invention the impeller 1 is movable along the axial
direction of the drive shaft 3.
Reference is now made to figs 3 and 4. In fig 3 is
shown a joint of the pump admitting axial movability of the
impeller 1 in relation to the drive shaft 3, at the same
time as the drive shaft 3 transmits a turning motion to the

9
impeller 1. The joint comprises a socket 13 provided in the
central hub 4 of the impeller 1, and connected to the
impeller 1 by means of bolts (not shown), or the like.
Alternatively the socket 13 may be integrated with the
impeller 1. The socket 13 presents a cavity 14 in a central
part thereof, which cavity 14 accommodate the second, lower
end of the drive shaft 3. In the preferred embodiment of
the present invention the drive shaft 3 is provided with a
sleeve 15 at the second, lower end thereof, the sleeve 15
being connected to the drive shaft 3 by means of a bolt 16
and/or key and keyway, or the like. Alternatively the
sleeve 15 may be integrated with the drive shaft 3.
The sleeve 15 has a first, upper part having a
first external diameter, which is essentially equal to the
internal diameter of a flange 17 of the socket 13. Further-
more, the sleeve 15 has a second, lower part having a dia-
meter larger than said first diameter of the sleeve 15. The
diameter of the second part of the sleeve 15 is essentially
equal to the internal diameter of the cavity 14. Due to
these dimensional relationships the impeller 1 is suspended
in the drive shaft 3. The cavity 14 presents a larger
extension in the axial direction than the second part of
the sleeve 15, the socket 13 and the impeller 1 being
movable a distance essentially equal to that difference.
In a first embodiment of the invention the joint
comprises at least one discrete element 18 arranged at the
interface between the socket 13 or impeller 1 and the
sleeve 15 or the drive shaft 3. The element 18 imperatively
transmits a turning motion from the drive shaft 3 to the
impeller 1 and admits the impeller 1 to move along the
drive shaft 3. The socket 13 is provided with a recess 19
for each element 18, the recess 19 extending in the axial
direction of the drive shaft 3. In the sleeve 15, opposite
to the recess 19 of the socket 13, is formed an interacting
recess 20, which together with the recess 19 of the socket
13 accommodate said element 18. In fig 3 the right element

10
18 is removed in order to get a general view of the
recesses 19, 20. In fig 4 the left and right element 18 are
removed. Preferably only two elements 18 are used and the
dimensions of the elements 18 are determined by the torque
being transmitted from the drive shaft 3 to the impeller 1.
In the shown embodiment in figs 1-4 the discrete element is
constituted by a bar, preferably a circular bar, due to a
manufacturing point of view.
It shall be pointed out that in an alternative
embodiment the discrete element 18 can be constituted by a
number of balls following the recess 19 of the sleeve 15 as
the impeller 1 moves in the axial direction. More
precisely, the recess 19 of the sleeve 15 has upper and
lower obstructions that prevent the balls from escaping
into the cavity 14. Alternatively, the discrete element 18
may be integrated with the inner surface of the sleeve 15,
i.e. ridges on the inner surface extending into the
recesses 19 of the socket 13.
The relative movability of the impeller 1 along
the drive shaft 3 may alternatively be realized by means of
a spline joint between the impeller 1 and the drive shaft
3, shown in figs 7 and 8. One advantage of using a spline
joint is that the joint will comprise fewer elements.
The impeller 1 is, in a preferred embodiment of
the present invention, freely movable along the drive shaft
3 since there are no springs or the like obstructing the
movement. More precisely, any force from a solid matter on
the impeller 1 from underneath that overcomes the high
pressure on the top side of the impeller 1 will manage to
raise the impeller 1 from the impeller seat 2. When the
solid matter is removed the impeller 1 automatically will
return to the lower position according to fig 1 since the
pressure on the top side of the impeller 1 is higher than
the pressure on the bottom side of the impeller 1.
Alternatively, the impeller 1 may, when the pump
is about to be started, be biased to the upper position

11
according to fig 2 by means of a spring. Not until the pump
is started and the liquid starts to flow the impeller 1
will move towards the impeller seat 2. This will prevent
the impeller 1 from shaking inside the pump housing during
transportation. In addition, the starting torque for the
impeller 1 is lowered since the impeller 1 and the impeller
seat 2 are well distanced from each other.
If a large piece of solid matter enters the open
channel 8 of the impeller seat 2, it is too large to get
in-between the vane 5 of the impeller 1 and the top surface
9 of the impeller seat 2. But the groove 10 in conjunction
with the vane 5 of the impeller 1 grabs hold of the solid
matter and forces it to "climb" over the top surface 9 of
the impeller seat 2 along the groove 10.
Finally, it shall be pointed out that the most
preferred number of grooves 10 is one. Furthermore, the
pump shall preferably comprise one guide pin 11. Otherwise
the open channel 8 should be too obstructed, which would
adversely affect the function of the pump.
Feasible modifications of the Invention
The invention is not limited only to the embodi-
ments described above and shown in the drawings. Thus, the
pump, or more precisely the impeller seat may be modified
in all kinds of ways within the scope of the appended
claims.
It shall be pointed out that instead of the
impeller being movable along the drive shaft the axial
movability may be achieved in a lot of ways, e.g. both the
drive shaft and the impeller may be movable away from the
impeller seat, or the impeller seat may be movable away
from the impeller, or both the impeller and the impeller
seat may be movable away from each other. In addition, only
the vanes may be movable in the axial direction in relation
to the hub of the impeller. For example, each vane is
individually movable and runs in a groove on the outside of

12
the hub, thereby at least one part of the vane is movable
in the axial direction in relation to the impeller seat.

13
Claims
1. A pump for pumping contaminated liquid including solid
matter, comprising a pump housing provided with a rotatable
impeller (1) suspended in a drive shaft (3) and having at
least one vane (5), and an impeller seat (2), at least one
part of the impeller (1) and the impeller seat (2), during
operation of the pump, being movable in the axial direction
in relation to each other, characterized in that the
impeller seat (2) presents at least one groove (10) in the
top surface (9) thereof.
2. A pump according to claim 1, wherein the impeller (1) is
movable at least 15 mm from the impeller seat (2).
3. A pump according to claim 1 or 2, wherein the impeller
(1) is movable at least 40 mm from the impeller seat (2).
4. A pump according to any of the claim 1-3, wherein the
groove (10) extends from a centrally located open channel
(8) in the impeller seat (2) to the periphery thereof.
5. A pump according to any of the claims 1-4, wherein the
groove (10) extends in a spiral shape, from the open
channel (8) and outwards along the direction of rotation of
the impeller (1).
6. A pump according to claim 5, wherein the vane (5) of the
impeller (1) extends in a spiral shape in the opposite
direction to the spiral shape of the groove (10).
7. A pump according to any of the preceding claims, wherein
the impeller (1) is freely movable in the axial direction
in relation to the drive shaft (3).

14
8. A pump according to claim any of the preceding claims,
wherein the pump comprises at least one discrete element
(18) arranged at an interface between the impeller (1) and
the drive shaft (3).
9. A pump according to claim 8, wherein the impeller (1)
and the drive shaft (3) presents recesses (19, 20) in the
opposite surfaces at said interface, which recesses (19,
20) jointly accommodate said element (18).
10. A pump according to claim 8 or 9, wherein the interface
accommodate at least two discrete elements (18), which are
equidistant separated from each other along the
circumference of the drive shaft.
11. A pump according to any of the claims 8-10, wherein each
element (18) comprises a bar extending in the longitudinal
direction of the drive shaft (3).
12. A pump according to any of the preceding claims, wherein
a guide pin (11) extends from the impeller seat (9) towards
the center of the impeller (1) and is located adjacent to
said groove (10).

The invention relates to a pump for pumping contaminated
liquid including solid matter, comprising a pump housing
provided with a rotatable impeller suspended in a drive
shaft and having at least one vane, and an impeller seat,
at least one part of the impeller and the impeller seat
being movable in the axial direction in relation to each
other. Furthermore, the impeller seat presents at least one
groove in the top surface thereof.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=8BymfE290me92h9e0Cpypg==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

271504

Indian Patent Application Number

375/KOLNP/2008

PG Journal Number

09/2016

Publication Date

26-Feb-2016

Grant Date

24-Feb-2016

Date of Filing

28-Jan-2008

Name of Patentee

XYLEM IP HOLDING LLC

Applicant Address

1133 WESTCHESTER AVENUE,WHITE PLAINS,NY 10604

Inventors:

#	Inventor's Name	Inventor's Address
1	ANDERSSON, PATRICK	VARVAGEN 1, S-11452 SKOGAS

PCT International Classification Number

F04D 7/04,F04D 29/04

PCT International Application Number

PCT/SE2006/000662

PCT International Filing date

2006-06-05

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	0501542-5	2005-07-01	Sweden