EP1840380A2

EP1840380A2 - Improved magnetic drive pump

Info

Publication number: EP1840380A2
Application number: EP07006477A
Authority: EP
Inventors: Luca Armellin; Alessandro Don; Giulio Tanghetti
Original assignee: METELLI SpA
Current assignee: METELLI SpA
Priority date: 2006-03-30
Filing date: 2007-03-29
Publication date: 2007-10-03
Also published as: ITBS20060079A1; EP1840380A3

Abstract

An improved magnetic drive pump especially usable for moving and circulating cooling fluids in internal combustion engines, comprising an impeller (12) keyed at the bottom erd of a shaped pin (14, 14A, 14B) turnably arranged relative to an annular body (18), a "cup" body (30, 30A, 30B) constrained to the top end of said shaped pin (14, 14A, 14B), a partition (40) attached by a threaded connection or other known type to a container body (28) obtained by fusion of aluminium or other suitable material, a further "cup" body (52) keyed to the bottom end of a shaft (48) on the top end whereof a pulley (46) is keyed, said pump further comprising means for supporting the rotation of the impeller (12), magnetic means respectively arranged on the outer surface of the "cup" body (30, 30A, 30B) and on the inner surface of the further "cup" body (52) and separated by the partition (40) and means for compensating or reducing the radial and axial mechanical stresses on the partition (40).

Description

The present invention relates to an improved magnetic drive pump.
More in particular, the present invention relates to a pump as defined above especially usable for moving and circulating cooling fluids in internal combustion engines.
As is known, in particular but not exclusively as regards internal combustion engines, during the operation of the same some of the components and circuits thereof reach very high temperatures and as such, hazardous and harmful both for the function and for the useful life of the engine itself; there is therefore the need of providing for cooling such parts through the dissipation of excess heat. To this end, the engine is provided with a cooling fluid circulation system. In a preferred but non-limiting manner, the circulation of such fluid is obtained by using so-called magnetic drive pumps that allow the fluid circulation keeping a temperature level suitable for proper and durable engine operation.
In this type of pump, the impeller is placed in rotation by the magnetic field induced through a series of permanent magnets arranged in coaxial direction relative to the inner body this type of pump exhibits the considerable advantage of not requiring the presence of a mechanical seal, required in the case of electrical or mechanical pumps and subject to frequent breakage.
In order to avoid fluid leaks, such pumps are provided with a partition, basically made of plastic material, which is attached to a pin through a threaded connection or by interference, on which the impeller of the pump itself is keyed.
However, said magnetic drive pumps exhibit an important disadvantage, related to the fact that the impeller rotation causes the onset of radial and axial loads that generate stresses on the pin attached to the partition, which could bring about the breakage of the partition itself due to fatigue.
The object of the present invention is to obviate the disadvantage mentioned hereinabove.
More in particular, the object of the present invention is to provide an improved magnetic drive pump which should allow avoiding the onset of mechanical stresses on the partition and the consequent risks of breakage of the same due to fatigue, and thereby of leaking of the cooling fluid at the components inside the pump itself.
A further object of the present invention is to provide the users with a magnetic drive pump intended for ensuring high level! of resistance and reliability over time, which should be quick and easy to assemble and also such as to be easily and inexpensively constructed.
These and other objects are achieved by the improved magnetic drive pump of the present invention which comprises an impeller keyed at the bottom end of a shaped pin turnably arranged relative to an annular body, a "cup" body constrained to the top end of said shaped pin, a partition attached by a threaded connection or other known type to a container body obtained by fusion of aluminium or other suitable material, a further "cup" body keyed to the bottom end of a shaft on the top end whereof a pulley is keyed, said pump further comprises means for supporting the rotation of the impeller, magnetic means respectively arranged on the outer surface of the "cup" body and on the inner surface of the further "cup" body and separated by the partition and means for compensating or reducing the radial and axial mechanical stresses on the partition.
The construction and functional features of the improved magnetic drive pump of the present invention shall be better understood from the following detailed description, wherein reference is made to the annexed drawing tables showing a preferred and non-limiting embodiment thereof, wherein:

figure 1 shows a schematic and axonometric view of a longitudinal section of the improved magnetic drive pump according to the present invention;
figure 2 shows a schematic axonometric view of a longitudinal section of a set of inner components making the rotor group of the pump object of the invention;
figure 3 shows a schematic axonometric view of a further set of inner components making the rotor group of the pump of figure 2;
figure 4 shows a schematic and axonometric view of a longitudinal section of an optional configuration of the pump object of the invention;
figure 5 shows a schematic axonometric view of a longitudinal section of a device of the invention according to a preferred embodiment;
figure 6 shows an axonometric detail of the device of the previous figure.

With reference to the above figures, the improved magnetic drive pump of the present invention, indicated with reference numeral 10 in figure 1, consists of an impeller 12, in se known and keyed, for example with a connection by interference or other known type, to the bottom end of a shaped pin 14; in a possible alternative embodiment not shown, impeller 12 and the shaped pin 14 are obtained, for example by moulding, in a single piece.
On the shaped pin 14, in the proximity of the bottom end thereof and on the side facing the bottom front of impeller 12, there is axially arranged a brass 16 of known type or more conventional bearings intended for supporting the rotation motion of the shaped pin 14 on which, as said above, impeller 12 is keyed, and for compensating or reducing the radial mechanical stresses as explained hereinafter.
With particular reference to figures 2 and 3, coaxial to the shaped pin 14 there is arranged an annular body 18, of basically circular shape and consisting of a ring 20 from the bottom front whereof, facing the bottom front of impeller 12, three or more appendices 22 develop, which extend by a first portion in vertical direction and downwards, then bending and extending radially inwards of the annular body 18, and according to a direction basically orthogonal to the axis of the same annular body, in as many radii 24; said radii 24 connect, in the proximity of the centre of the annular body 18, to a hub 26 arranged external to brasses 16 and coaxially thereto.
Moreover, annular body 18 is attached by interference, by a threaded connection or other known way to the bottom portion of the outer side surface of a container body 28, as schematised in figure 1. Said container body 28 is advantageously mace by fusion of aluminium alloy or other suitable material and intended for attaching the pump, for example relative to the internal combustion engine.
A "cup" body 30, with substantially circular section, is keyed by interference or by other known types of constraint at the top end of the shaped pin 14 opposite impeller 12; the same "cup" body 30 is also partly fitted on hub 26 of the annular body 18, as schematised in figure 2.
Starting from the bottom front of the "cup" body 30 facing the impeller 12, along all the base perimeter of the aforesaid body, an annular lip 32 develops, whose function shall be described hereinafter. The same "cup" body 30, on the top base opposite impeller 12, defines the seat of a first ceramic element 34, which is defined by a bottom portion, corresponding to the portion inserted in the above seat, with basically polygonal section, and by a top portion with preferably conical shape and extending opposite impeller 12. Said first ceramic element 34, which is preferably made of Z_rO₂-Y₂O₃ (ceramic material based on co-precipitated zirconium oxide partly stabilised with yttrium oxide), is stabilised in the seat of the "cup" body 30 by a first support 36 of rubber or other suitable material; moreover, the polygonal section of the bottom portion of said first ceramic element 34 has the function of preventing the relative rotation of the same first ceramic element relative to the impeller 12.
According to a further feature of the invention, on the outer side surface of the "cup" body 30, in axial direction and in abutment on the annular lip 32 of the same "cup" body 30, there is inserted a magnetic group 38 consisting of multiple magnets that preferably but not critically are radially polarised permanent magnets; said magnets making up the magnetic group 38 are for example made of NdFeB (plastic neodimium) or other suitable material. According to a further advantageous configuration of the invention, the magnetic group 38 consists of a single magnetic ring, of the same material making the plurality of permanent magnets mentioned above, and obtained according to known techniques as a single body or pressed ring.
The set of components consisting of impeller 12, shape pin 14, "cup" body 30 and magnetic group 38 makes up the rotor group placed in rotation by the inductor group described hereinafter.
The above rotor group and the inductor group are separate from each other by a partition 40; said partition 40 shaped as a "cup" and with a basically circular profile, as schematically represented in figure 1, starting from the top front thereof facing impeller 12 forms an appendix or lip 40' which develops circumferentially by first portion, in basically horizontal direction to then bend and extend by a second portion, parallel to the side surface of the partition itself, and opposite the attachment direction of impeller 12. Partition 40, on the inner surface and at the centre of the bottom base thereof, forms a projection 40" which, developing vertically and shaped as a circular ring in the direction of impeller 12, makes up the seat of a second ceramic element 42. Such second ceramic element 42 like the first ceramic element 34, has a basically polygonal section and on the bottom base, facing the first ceramic element 34, forms a depression or recess with preferably conical shape and such as to define the coupling, substantially by a single contact point, with the top conical portion of the same first ceramic element 34. Also the second ceramic element 42 is stabilised inside projection 40" by a second support 44, made of rubber or other suitable material; like the first ceramic element 34, also the second ceramic element 42 is preferably made of Z_rO₂-Y₂O₃.
Partition 40 is constrained, at the second portion of lip 40' of the same partition and by a threaded connection or by interference, with "O-Rings" or other known type of constraint, to the inner surface of the container body 28; such partition 40, as described above, has the advantageous function of ensuring the mechanical seral preventing the leak of the cooling fluid inside the container body 28 of pump 10. On the top end of the container body 28, opposite impeller 12, there is fitted a pulley 46 which is keyed on a shaft 48 with differentiated diameters cooperating with one or more bearings 50, arranged on the same shaft inside the container body 28.
A further "cup" body 52, with basically circular base and with the side surface with cylindrical development, is keyed or the bottom end of shaft 48, locked relative to the same by interference or other known type of constraint, and fitted on partition 40. In said further "cup" body 52, in axial direction and attached to the inner side surface of the same, there is inserted a second magnetic group 54 which, like magnetic group 38 of the "cup" body 30, is equally comprised of multiple magnets, preferably but not critically radially polarised permanent magnets; also the second magnetic group 54, according to a further advantageous configuration of the invention, is comprised of a single magnetic ring, of the same material making the above plurality of permanent magnets, and obtained according to known techniques as a single body or pressed ring.
Said second magnetic group 54 is coaxial relative to magnetic group 38 and is separated therefrom by partition 40. The assembly made up of the "cup" body 52 and of the second magnetic group 54 defines the inductor group that places the rotor group described above in rotation as described hereinafter.
Figure 4 shows an embodiment alternative to that described above for the magnetic drive pump of the invention; in said figure, for common parts and components the same reference numerals as the previous solution are used. In such alternative embodiment, impeller 12 is keyed, for example with a connection by interference or of other known type, to the bottom end of a shaped pin 14A; however, it is understood that as with the preferred embodiment described above, impeller 12 and the shaped pin 14 may be obtained, for example by pressing, as a single piece.
On the shaped pin 14A there is axially arranged a flanged brass 16A of known type or one or more conventional bearings intended for supporting the rotation motion of the shaped pin 14A on which, as said above, impeller 12 is keyed; said flanged brass 16A, moreover, is arranged with the bottom front of the flange in abutment with the free top front of the shaped pin 14A opposite the bottom one for the attachment to impeller 12 and is constrained by interference or other way to hub 26 of the annular body 18.
A "cup" body 30A, with substantially circular section, is keyed by interference or by other known types of constraint at the top end, opposite impeller 12, of the shaped pin 14A; the same "cup" body 30A is also partly fitted on hub 26 of the annular body 18.
Starting from the bottom front of the "cup" body 30 facing the impeller 12, along all the base perimeter of the aforesaid body, an annular lip 32 develops, having the same function described above.
As regards the other component elements of the magnetic drive pump in the alternative embodiment thereof, since they are equal to those of the preferred embodiment, they shall not be further described again.
With reference to the preferred configuration, the operation of the magnetic drive pump of the invention shall be described hereinafter.
When pulley 46 is placed in rotation by a belt, for example of toothed type (not shown in the figures), it pulls the further "cup" body 52 and thereby the second magnetic group 54 inserted therein in its motion; as a consequence thereof, and considering that the magnetic group 38 and the second magnetic group 54 are radially polarised, also the magnetic group 38 of the "cup" body 30 sets in rotation by the effect of the magnetic field induced by the second magnetic group 54. The rotation of the "cup" body 30 and thereby of the shaped pin 14 the "cup" body 30 is constrained to, determines the synchronous rotation of impeller 12 relative to the further "cup" body 52.
By the effect of the rotation of the rotor group by the inductor group, radial step-wise loads are generated on impeller 12 which, in ther preferred embodiment are advantageously relieved on the container body 28 through brass 16 and the annular body 18; in the alternative embodiment the same radial loads are equally relieved on the container body 28 through the flanged brass 16A and the same annular body 18.
The rotation of the rotor group relative to the inductor group also generates axial loads that in the preferred embodimerit are relieved through the prod of the first ceramic element 34 on the second ceramic element 42; in the alternative embodiment, on the other hand, the same axial loads are relieved through the flange of the flanged brass 16A.
Moreover, considering that in order to keep a balanced condition, when the magnetic group 38 and the second magnetic group 5 are not aligned they tend to axially attract each other, the axial loads are not fully relieved through the prod of the first ceramic element 34 on the second ceramic element 42, but they are partly advantageously compensated by the above magnetic attraction force.
As a consequence, the loads acting on partition 40 are considerably reduced to a value close to zero, with the advantage of extending the useful life of the partition itself and thereby the pump quality and reliability.
With special reference to the preferred embodiment of the pump of the invention, the high temperatures that generate in the point of contact between the first ceramic element 34 and the second ceramic element 42, due to the rotation of the rotor group and to the friction generated between said first ceramic element 34 and second ceramic element 42, are localised and thanks to the advantageous use of the ceramic materials there is no heat propagation by conduction to the other pump elements.
Figures 5 and 6 show another preferred embodiment. The same reference numerals of the previous solutions are used in said figures for common parts and components.
In such alternative preferred embodiment, impeller 12 is keyed, for example with a connection by interference or of other known type, to the bottom end of a shaped pin 14B hollow therein; however, it is understood that as with the preferred embodiment described above, impeller 12 and the shaped pin 14B may be obtained, for example by pressing, as a single piece.
Coaxial to the shaped pin 14B there is arranged a flanged body 60, with basically circular section and shaped as a "cup" constrained in known manner to the container body 28. Said flanged body 60, at the central zone thereof, exhibits an annular element 62, which develops opposite impeller 12.
Coaxial to the shaped pin 14B and inside the annular element 62 of the flanged body 60 there is arranged a brass 16B of conventional type or one or more bearings intended for supporting the rotation motion of the shaped pin itself.
On the bottom of the flanged body 60 there is obtained, according to a circumference concentric to the annular element 62, at least one through hole 64 whose function is detailed hereinafter.
At least one ring 66 is arranged coaxial to the shaped pin 14B and is stiffly constrained relative to the top front of the annular element 62 of the flanged body 60. Said ring 66, made of graphite or other suitable material, has the function of compensating the axial stresses exerted on impeller 12 and on partition 40. In alternative embodiments, one or more conventional axial thrust bearings may be used in replacement of ring 66.
Coaxial to the shaped pin 14B there is arranged a disc 68 which is attached by the front thereof to the bottom front of a "cup" body 306 (having a function similar to the "cup" body 30 and 30A described hereinbefore); said disc is made of a metal material, for example steel, and rotates along with the "cup" body 30B and with the shaped pin 14B.
Inside said disc 68 there is obtained a pocket or slot 70 extended by the entire circumference of the disc itself; such pocket or slot 70 communicates with the top front of disc 68 through one or more holes 72.
At the above holes 72 of disc 68 and in substantially axial direction, the "cup" body 30B exhibits one or more channels 74 intended for carrying out the function described hereinafter.
During the pump operation the cooling fluid penetrates, through hole(s) 64 into the flanged body 60, flows through the region or space comprised between ring 66 and the shaped pin 14B and passes into slot 70 of disc 68; then, from slot 70 the cooling fluid passes through the one or more channels 74 and comirig out thereof returns through the shaped pin 14B which is hollow therein.
In this way the cooling fluid advantageously allows cooling and lubricating the rotating elements of the pump and consequently extends the useful life of the same components and thereby of the pump.
Even if the invention has been described hereinbefore with particular reference to an embodiment thereof made by way of a non-limiting example only, several changes and variations will appear clearly to a man skilled in the art in the light of the above description. The present invention therefore is intended to include any changes and variations thereof falling within the spirit and the scope of the following claims.

Claims

An improved magnetic drive pump especial usable for moving and circulating cooling fluids in internal combustion engines, comprising an impeller (12) keyed at the bottom end of a shaped pin (14, 14A, 14B) turnably arranged relative to an annular body (18), a "cup" body (30, 30A, 30B) constrained to the top end of said shaped pin (14, 14A, 14B), a partition (40) attached by a threaded connection or other known type to a container body (28) obtained by fusion of aluminium or other suitable material, a further "cup" body (52) keyed to the bottom end of a shaft (48) on the top end whereof a pulley (46) is keyed, said pump being characterised in that it comprises:
- means for supporting the impeller rotation (12);

- magnetic means respectively arranged on the outer surface of the "cup" body (30, 30A, 30B) and on the inner surface of the further "cup" body (52) and separated by the partition (40);

- means for compensating or reducing the radial and axial mechanical stresses on the partition (40).
The magnetic drive pump according to claim 1, characterised in that the means for supporting the rotation of the impeller (12) are comprised of a brass (16, 16B) or a flanged brass (16A) axially arranged on a shaped pin (14, 14A, 14B) in the proximity of the bottom end thereof and facing the bottom front of the impeller (12).
The magnetic drive pump according to the previous claims, characterised in that the means for supporting the rotation of the impeller (12) are comprised of one or more bearings axially arranged on a shaped pin (14, 14A, 14B) in the proximity of the bottom end thereof and facing the bottom front of the impeller (12).
The magnetic drive pump according to any one of the previous claims, characterised in that the magnetic means are comprised of a magnetic group (38) and of a second magnetic group (54) each consisting of multiple magnets.
The magnetic drive pump according to any one of the previous claims, characterised in that at least one of said magnetic means is comprised of a magnetic ring obtained as a single body.
The magnetic drive pump according to any one of the previous claims, characterised in that each magnetic means is comprised of a magnetic ring obtained as a single body.
The magnetic drive pump according to any one of the previous claims, characterised in that the magnets making up the magnetic group (38) and/or the second magnetic group (54) are made of NdFeB (plastic neodimium).
The magnetic drive pump according to any one of the previous claims, characterised in that the magnets making up the magnetic group (38) and/or the second magnetic group (54) are radially polarised.
The magnetic drive pump according to any one of the previous claims, characterised in that the means for reducing the radial mechanical stresses on the partition (40) consist of the brass (16) and of the annular body (18) of basically circular shape, consisting of a ring (20) from the bottom front whereof, facing the bottom front of the impeller (12), three or more appendices (22) develop, which extend by a first portion in vertical direction and downwards, then bending and extending radially inwards of the annular body (18) and according to a direction orthogonal to the axis of the same annular body, in as many radii (24) that connect, in the proximity of the centre of the annular body (18), to a hub (26) arranged external to the brasses (16) and coaxially thereto.
The magnetic drive pump according to any one of the previous claims, characterised in that the means for reducing the axial mechanical stresses on the partition (4C) consist of a first ceramic element (34) and of a second ceramic element (42) respectively arranged on the top base of the "cup" body (30), opposite the impeller (12), and in a projection (40") shaped as a circular ring formed at the centre of the bottom base of the inner surface of the partition (40) and developing vertically in the direction of the same impeller (12).
The magnetic drive pump according to any one of the previous claims, characterised in that the first ceramic element (34) and the second ceramic element (42) are made of Z_rO₂-Y₂O₃.
The magnetic drive pump according to any one of the previous claims, characterised in that the first ceramic element (34) is defined by a bottom portion of polygonal section and by a top portion of conical shape, extending in direction opposite that of the impeller (12), and the second ceramic element (42) has a polygonal section with a depression or recess with polygonal shape formed on the bottom base thereof facing the first ceramic element (34).
The magnetic drive pump according to any one of the previous claims, characterised in that the first ceramic element (34) and the second ceramic element (42) are respectively stabilised on the top base of the "cup" body (30) and in a projection (40") by a first support (36) and a second support (44) made of rubber or other suitable material.
The magnetic drive pump according to any one of the previous claims, characterised in that the means for reducing the radial and axial mechanical stresses on the partition (40) consist of the flanged brass (16A) and of the annular body (18).
The magnetic drive pump according to any one of the previous claims, characterised in that the means for reducing the radial and axial mechanical stresses on the partition (40) consist of one or more bearings and of the annular body (18).
The magnetic drive pump according to any one of the previous claims, characterised in that the impeller (12) and the shaped pin (14, 14A) are made by pressing as a single piece.
The magnetic drive pump according to any one of the previous claims, characterised in that the means for reducing the axial mechanical stresses on the partition (40) consist of at least one ring (66).
The magnetic drive pump according to any one of the previous claims, characterised in that the ring (66) is stiffly constrained to the top front of an annular element (62) obtained at the central zone of a flanged body (60).
The magnetic drive pump according to any one of the previous claims, characterised in that the flanged body (60) exhibits at least one through hole (64) obtained according to a circumference concentric to the annular element (62).
The magnetic drive pump according to any one of the previous claims, characterised in that coaxial to the shaped pin (14B) there is arranged a disc (68) attached by the top front thereof to the bottom front of the "cup" body (30B), with said disc (68) which internally exhibits a pocket or slot (70) extending by the entire circumference of the disc itself and communicating with the top front of the disc itself (68) through one or more holes (72).
The magnetic drive pump according to any one of the previous claims, characterised in that the "cup" body (30B) exhibits, in substantially axial direction, one or more channels (74) obtained at the holes (72) of the disc (68).