WO2000037804A1

WO2000037804A1 - Power driven device with centrifugal fluid circulation, such as a motor pump or a motor compressor

Info

Publication number: WO2000037804A1
Application number: PCT/FR1999/003241
Authority: WO
Inventors: Dominique Cucini; Philippe Gyomlai; Raymond Michaux
Original assignee: Jeumont Sa
Priority date: 1998-12-22
Filing date: 1999-12-21
Publication date: 2000-06-29
Also published as: EP1147318A1; FR2787527B1; AU1785000A; FR2787527A1; ATE253689T1; DE69912644D1; EP1147318B1

Abstract

The invention concerns a device comprising a sealed body (2) and at least a wheel (10) mounted rotating in the sealed body (2), about a fixed axis of rotation (3) comprising at least a fluid intake (4) in its central part and a plurality of channels (13) circulating the fluid in a substantially radial direction between the central fluid intake (4) and the wheel (10) periphery, and an electric motor driving the wheel. The motor rotor is integral with the wheel (10) and arranged opposite at least one stator (17) element fixed in the body (2) of the device (1). The wheel (10) bears, on at least a lateral surface opposite a part of the sealed body (2), at least a magnetic element (18c) located opposite a corresponding magnetic element (18a, 18b) integral with the sealed body (2) to form an axial magnetic stop. The invention is applicable in particular to a motor pump or a motor compressor for a toxic fluid.

Description

Motorized device with centrifugal fluid circulation, such as a motor pump or a motor compressor

The invention relates to a motorized device with centrifugal fluid circulation, such as a motor pump or a motor compressor and, in particular, a sealed motor pump or motor compressor, for pumping or compressing toxic fluids.

For pumping or compressing toxic fluids, motor-pump or motor-compressor units are used comprising a sealed body, in which at least one wheel is rotatably mounted around an axis of rotation and driven in rotation by an electric motor.

The pump or compressor impeller has a fluid inlet, in a central zone, that is to say close to the axis of rotation, and a plurality of fluid circulation channels, between the central inlet fluid and the periphery of the wheel. The fluid which is pumped or compressed is introduced into the pump or compressor body, through a central opening of the pump body communicating with the central opening of the impeller. The drive shaft of the rotating wheel passes through the wall of the pump or compressor body in a sealed manner, to be connected to a drive motor.

So as to reduce the size of the pump units, improve their operation and reduce their construction cost, it has been proposed, for example in FR-A-2,732,412, to drive the pump wheel by a motor, for example of the discoid type, the stator and rotor of which are arranged inside the pump body. The motor may include one or more rotors integral with one or more pump wheels, all of the rotors and pump wheels being rotatably mounted on a common shaft. Each disc-shaped rotor is inserted, in the axial direction of the motor and the pump, between two stators integral with the pump body. The assembly constituted by the pump wheel (s) and the rotor (s) is rotated inside the pump body filled with liquid to be pumped. This results in yield losses by hydraulic friction between the rotor (s) and the fluid to be pumped. In addition, the achievement of the group motor pump is relatively complex and expensive, insofar as it is necessary to machine and produce separately the wheels and the rotors which are assembled before their mounting in the pump body. Finally, the axial size of the pump unit can be relatively large, insofar as it is necessary to provide an axial spacing between the wheels and the rotors and between the rotors fixed on the same shaft.

Fluid agitators or pumps have also been proposed comprising a stirring wheel or propeller on which is fixed a rotor element which is rotated by a rotating field created by a stator. These devices have advantages over conventional motorized pumps. In particular, the number of components of the pump is reduced, the stator can be produced at a lower cost and a substantial gain is obtained with regard to the mass and size of the pump. However, these devices have drawbacks, in particular due to the axial magnetic attraction exerted by the stator on the rotor which can be significant, both when the pump is stopped and when it is in operation. In addition, the efficiency of the motor pump is reduced due to significant losses by hydraulic friction at the periphery of the electric rotor.

The axial positioning of the rotor of such motor pump units which are said to have an embedded rotor is generally achieved by a hydrodynamic stop which is lubricated by the fluid circulated by the pump.

The forces exerted on the pump rotor are constituted by hydraulic forces and magnetic forces.

The hydraulic forces come from the distribution of the internal pressures of the fluid linked to the refrigeration flow in the bearings and the internal sealing devices such as labyrinth seals or air gaps as well as to the different pressure drops in these parts of the circuits. motor pump. These hydraulic forces vary as a function of the discharge pressure and the speed of rotation of the pump. The magnetic force comes from the attraction generated in the air gap by the average induction of the electric motor. This magnetic force varies little as a function of the speed of rotation.

It turned out that, due to the large forces exerted on the rotor of a motor-driven pump with submerged rotor, the hydrodynamic stops used until now are at the origin of most incidents of pump operation. , due to heating problems or insufficient lubrication during certain phases of operation, or during dry operation. As a result, the reliability requirements demanded by the users of such pump units go in the direction of eliminating the hydrodynamic stops and replacing them with other balancing systems.

The object of the invention is therefore to propose a motorized device for centrifugal circulation of a fluid such as a motor pump or a motor compressor, comprising a sealed body and at least one wheel mounted to rotate about an axis of rotation in the sealed body, comprising at least one fluid inlet at its central part and a plurality of fluid circulation channels of substantially radial direction, between the central fluid inlet and the periphery of the wheel, as well as an electric motor d wheel drive comprising a stator and a rotor integral in rotation with the wheel, this device making it possible to reduce losses by hydraulic friction, to reduce the overall size and weight of the device, to reduce costs manufacturing and providing a satisfactory axial maintenance of the rotor, in all the operating phases of the device. For this purpose :

the rotor, produced in discoid form, is integrated into the wheel and disposed opposite at least one stator element fixed in the sealed body of the device, and

the pump impeller carries, on at least one lateral face facing a part of the sealed body, at least one magnetic element placed opposite a corresponding magnetic element secured to the part of the sealed body to constitute at least one stop exerting on the wheel and the rotor a force of magnetic origin of axial direction. Preferably, the device further comprises hydrodynamic stops and / or mechanical stops to supplement or supplement the action of the magnetic elements, at least in certain operating phases of the device. In order to clearly understand the invention, a description will be given, by way of example, with reference to the attached figures, of several embodiments of a motor pump unit according to the invention used for pumping fluids, in particular toxic fluids. .

FIG. 1 is a half-view in axial section of a motor pump according to the invention and according to a first embodiment.

FIG. 2A is a schematic view of a permanent magnet stop which can be used to achieve axial balancing of the rotor of the device shown in FIG. 1.

FIG. 2B is a schematic view of an electromagnetic stop which can be used to carry out axial balancing of the rotor of the device shown in FIG. 1.

Figure 3 is an enlarged view of part of Figure 1 showing an embodiment of a hydraulic balancing of the impeller of the motor pump.

FIG. 4 is a half view in axial section of a motor pump according to the invention and according to a second embodiment.

Figure 5 is a half view in axial section of a motor pump according to the invention and according to a third embodiment.

Figure 6 is a half view in axial section of a motor pump according to the invention and according to a fourth embodiment. Figure 7 is a half view in axial section of a motor pump according to the invention and according to a fifth embodiment.

Figure 8 is a half view in axial section of a motor pump according to the invention and according to a sixth embodiment.

In the following description, the corresponding elements of the pump units shown in Figures 1 to 5 are assigned the same references.

In Figure 1, we see a motor pump group generally designated by the reference 1 which includes a housing or pump body designated generally by the reference 2 which is made of several parts assembled together in a sealed manner by means of static seals.

The pump body 2 comprises for example, as shown in FIG. 1, a front flange 2a and a rear flange 2b assembled together by screws and nuts, with interposition of a seal.

Inside the front flange 2a is machined a fluid inlet space 4 in the central part of the pump set 1, around the axis 3 of the pump set. The fluid inlet space 4 is connected, via a nozzle, to a fluid inlet in the central part of the pump set.

In the front flange 2a is also machined a fluid outlet space 5 communicating with a tube 5 'at the peripheral part of the pump set. The front flange 2a and the rear flange 2b define between them an internal space 8 of the pump body 2 having as axis of symmetry the axis 3 of the pump set. The internal space 8 of the pump is isolated from the outside by the seals inserted between the flanges 2a and 2b of the pump body 2. In the internal space 8 of the pump set, the rotating part of the pump is mounted. motor pump constituted by the pump wheel 10 and the rotor 16 of the drive motor 15 of the pump.

The pump impeller 10 comprises curved channels 13 and of substantially radial direction, a first end of which is in communication with a central outlet of the pump impeller communicating with the inlet space 4 of the pump and of which a second end leads to the peripheral surface of the pump wheel 10, in a radial direction, inside the outlet space 5 of the pump communicating with the outlet pipe 5 '. The pump impeller and the rotor 16 are rotatably mounted inside the internal space 8 of the pump body 2, by means of a shaft 6 having the geometric axis axis 3 of the pump unit and a rotary bearing 7 which is produced in the form of a smooth bearing. The shaft 6 is engaged, by a first end portion, in an opening of the front flange 2a and, by a second opposite end portion, in an opening of the rear flange 2b, the openings of the flanges in which the end parts of the shaft 6 being arranged along the axis 3 of the motor pump. The shaft is further fixed by a screw in the rear flange 2b of the pump body. The plain bearing 7 includes an outer ring 7b secured to the rotating part of the pump unit and a fixed inner ring 7a coaxial with the rotating outer ring 7a and fixed on the shaft 6 of the pump unit. The fixed inner ring 7a of the plain bearing 7 is fixed on the shaft 6, by means of a fixing assembly 9 comprising an annular retaining part 9a and a tightening assembly 9b comprising a nut which is screwed on a part threaded from the shaft 6, a washer and a support piece on the retaining piece 9a. The fixed inner ring 7a of the bearing 7 is interposed and clamped between the retaining part 9a and a support ring 11 arranged at the second end of the bearing ring 7a.

The retaining part 9a has an external part projecting in the direction of a first end part of the movable ring 7b of the bearing 7 constituting a bearing stop for the movable ring 7b and of the assembly movable in rotation of the motor pump.

The first end of the movable ring 7b has a surface facing the bearing surface of the annular retaining part 9a by means of which the movable ring 7b of the bearing 7 can come to bear on the part retainer 9a. The second end of the mobile ring 7b in rotation of the bearing 7 is held by a support piece 12 fixed by a set of screws on the mobile part in rotation 10, 16 of the motor-driven pump.

The pump wheel 10 and the rotor 16 of the motor drive motor 15 are integral with one another and for example rigidly fixed to one another by means of screws and keys . For example, the fixing screws of the two parts 10, 16 of the rotary assembly of the motor-driven pump can also be used to fix the retaining part 12 of the ring 7b movable in rotation of the bearing 7 of the pump. The retaining part 9a constitutes a mechanical stop for retaining the rotating part of the pump, in the axial direction, this stop, disposed on the side of the fluid inlet 4 in the motor pump will be designated as the front stop. A rear abutment 14 is constituted by annular vis-à-vis integral parts, respectively, of the rotor 16 of the motor 15 and of a plate integral with the rear flange 2b of the pump body 2.

The electric motor 15 for driving the pump in rotation may be a synchronous permanent magnet motor comprising a rotor 16 constituted by a flange in which is fixed a cylinder head 16a of annular shape carrying magnets 16b distributed along the periphery of the cylinder head 16a and separated from each other by spacers 16c.

The active part of the rotor 16, namely the cylinder head and the permanent magnets, could be mounted directly in the part constituting the pump wheel instead of being mounted on a flange constituting the support part of the rotor 16 rigidly fixed on the pump impeller. In all cases, the rotor 16 is perfectly integrated into the pump wheel, of which it is integral.

The synchronous motor 15 further comprises elements of a stator 17 constituted by coils mounted in cavities machined in the rear flange 2b of the pump body 2. The cavities are filled with resin in which the coils and a plate are embedded. closure 17a of the cavities containing the windings of the stator 17 is fixed on the face of the rear flange 2b of the pump body 2 directed towards the front flange 2a and the internal space 8 of the motor pump 1.

The fact that the windings are embedded in the resin filling the stator cavities which are closed by the closing plate 17a makes it possible to avoid any contact between the stator windings and the fluid whose motor pump 1 ensures pumping. The permanent magnets of the rotor 16 are covered by protective sheets making it possible to avoid their contact with the pumping fluid.

To put the motor-pump into operation, the stator windings 17 are supplied with electric current via a power electronics constituting a frequency converter 48. The assembly constituted by the motor and the frequency variator makes it possible to obtain flexible control of the pump by variation of speed over a wide range of speeds. The frequency converter also makes it possible to obtain smooth starts of the pump set, avoiding violent jolts in the pipes, to protect the pump set in the event of motor overheating by causing an automatic stop and to integrate into the motor pump control, protection in the event of the pump underloading due to the absence of pumping fluid; the frequency converter then causes the pump to stop or slow down automatically.

In the case of the use of a synchronous motor, the air gap between the stator elements and the magnets of the rotor can be relatively large, of the order of 2 to 8 mm. Indeed, in this case, the air gap has little influence on the efficiency and on the cosine φ of the motor. It is then possible to use a wall 17a for closing the stator cavities of great thickness in an insulating material, for example in a non-magnetic metal or in a plastic material, which limits heating of the stator windings. A large choice of material is possible, insofar as the closure plate 17a of the stator can be produced in a very flat shape and fixed without welding between the two parts 2a and 2b of the pump body.

In the case of the pumping of a fluid at high temperature, for example a fluid at 350 ° C., it is necessary to use permanent magnets capable of withstanding these temperatures and in particular magnets of the samarium-cobalt type, certain shades of which can be used. up to 350 ° C. These magnets are however more expensive and less efficient than magnets of the neodymium-ferro-boron type.

Motor-pumps with submerged impellers having rotor elements integrated into the pump impeller which have just been described and as shown in FIG. 1 have many advantages.

However, these pump units have the disadvantage that a large axial directional force directed towards the stator is exerted on the rotating part of the pump comprising the rotor and the pump impeller, so that simple hydrodynamic stops lubricated by the fluid which is pumped are insufficient to reliably ensure the maintenance and axial guidance of the rotary assembly of the motor pump in all cases of operation. Hydrodynamic stops can be formed, for example, between parts facing mechanical stops, the surfaces of which have been machined so as to form a wedge of fluid therebetween. Such hydrodynamic stops can be produced for example, in the case of the pump shown in FIG. 1, by the surfaces facing the parts 9a and 7b of the front stop and between the facing surfaces. of the rear stop 14.

FIG. 3 shows on a larger scale a part of the motor-driven pump which is produced so as to provide a certain hydraulic balancing of the axial forces exerted on the rotor 16 secured to the pump wheel 10.

The air gap 43 of the motor 15 between the protective sheet 17a of the stator 17 and the protective sheet of the permanent magnets 16b of the rotor 16 is filled, during the operation of the pump, by pumping fluid arriving in the air gap by a space situated at the external periphery of the rotor 16 communicating, via a fluid rolling space 42, with the discharge part of the channels 13 of the pump impeller 10 in which the pumping fluid is at a pressure of delivery significantly higher than the suction pressure of the pump. The air gap 43 between the rotor and the stator is also in communication with the suction part of the pump by an internal rolling space 44 delimited between the two parts of the rear stop 14. The fluid rolling spaces 42 and 44 are delimited by surfaces of the rotor 16 and of the pump body 2 substantially perpendicular to the axis 3 of the pump. The space 42 located in an arrangement remote from the axis 3 of the pump is called the external fluid rolling space and the space 44, located towards the axis 3 is called the internal fluid rolling space. This communication of the air gap 43 with the discharge part and the suction part of the pump, respectively via the external rolling space 42 and by through the interior rolling space 44 allows axial hydraulic balancing of the rotor.

Indeed, in the case where the attraction exerted by the stator 17 on the rotor 16 increases above a certain limit, the rotating part of the motor-driven pump comprising the pump wheel 10 and the rotor 16 moves in the direction of the stator 17, by opening the upper laminating space of fluid 42 and by closing the lower space 44.

The communication of the air gap 43 with the high-pressure discharge part of the pump wheel 10 produces an increase in the pressure in the air gap 43, which generates an axial force which balances the increase in the force d attraction exerted by the stator 17 on the rotor 16 and the pump wheel.

If the attraction exerted by the stator 17 on the rotor 16 of the motor 15 decreases to a certain value, the rotating part of the motor pump comprising the wheel 10 and the rotor 16 moves away from the stator and closes the rolling space outside 42 at the same time as the inside space 44 opens. The air gap 43 is placed in communication with the suction part of the pump, so that the pressure in the air gap 43 decreases. The reduction in the pressure in the air gap causes a reduction in the axial hydraulic thrust force, which balances the rotor subjected to a lower force of attraction of the stator.

The hydraulic balancing effect is obtained from the fact that the air gap 43 constitutes a chamber separating the high pressure discharge part of the pump from the low pressure suction part. The suction pressure is channeled in the direction of the rolling space of the stop 14 by means of the central bore 6a of the shaft 6 and of radial bores 6b.

The use of hydrodynamic stops and / or of the hydraulic balancing effect of the pump obtained as described with reference to FIG. 3 does not systematically make it possible to satisfactorily compensate for the axial forces exerted on the rotating part of the pump comprising the rotor integrated in the pump wheel. According to the invention, magnetic stops are used which exert forces in the axial direction on the rotating part of the pump, in the opposite direction to the stator. As can be seen in FIG. 1, it is possible to use a magnetic stop 18 of which a fixed part is housed in the front flange 2a of the pump body and of which a mobile part in rotation is integral with the pump wheel 10 which is placed in opposite the fixed part.

In the embodiment shown in FIG. 1, the fixed part of the magnetic stop 18 comprises an annular yoke 18a fixed in the bottom of the annular cavity machined in the flange 2a of the pump body and at least one permanent magnet 18b fixed against the cylinder head 18a in the cavity of the flange 2a.

The element 18b can be produced in the form of a one-piece crown having the same inside and outside diameters as the annular yoke 18a. It is also possible to use several magnets distributed along the circumference of the cylinder head and separated from each other by spacer pieces, in an embodiment similar to the embodiment of the magnets 16b of the rotor 16.

The mobile part in rotation of the magnetic stop 18 is constituted by a collar 18c of annular shape integral with the front face of the pump wheel 10 and placed opposite the permanent magnet or magnets 18b of the fixed part of the stop. The collar 18c is made of soft iron or a magnetic material with high permeability which may be identical to the material of the yoke 18a of the stop. The face of the magnet 18b of the stopper directed towards the pump wheel 10 and the internal cavity 8 of the pump receiving the pumping fluid is covered by a protective sheet.

Likewise, the collar 18c integral with the pump wheel is covered, on its face directed towards the front, opposite the fixed part of the stop, by a protective plate.

An air gap 45 is delimited between the protective plates of the magnets 18b and of the collar 18c of the stop. As can be seen in FIG. 2A, the stop may include two annular rows of magnets 18b whose polarities are reversed, so that the circulation of the magnetic flux represented by thick arrows constitutes a closed loop inside the cylinder head and collar. The magnetic flux produces an attractive force in the air gap 45 between the collar 18c and the magnets 18b. One thus obtains a restoring force of the rotating assembly of the motor pump with submerged rotor in the opposite direction to the attractive force exerted by the stator 17 on the rotor 16. This thus compensates, at least partially, the force of attraction of the rotor, so as to balance the rotating part of the pump in the axial direction. A magnet stop such as stop 18 makes it possible to reduce the axial force on the rotor, of magnetic origin and of hydraulic origin, by a ratio close to 10.

A magnetic stop such as the stop 18 can be perfectly integrated into the impeller and the pump body. However, such a permanent magnet stop has drawbacks because the axial compensation force exerted on the rotating part of the pump cannot be adjusted according to the operating phases of the pump. In addition, the permanent magnets used are expensive products. Finally, the stiffness of the stop is negative, that is to say that the smaller the air gap, the greater the forces exerted by the stop. The stop is therefore, by nature, unstable and must be associated with a complementary stop device to allow acceptable operation of the stop in all operating conditions of the motor-driven pump.

The magnetic stop with permanent magnet can be associated with mechanical stops taking up residual axial forces in both directions, in the event of extreme operation of the motor-driven pump, for example in the case of an absence of pumping fluid. These mechanical stops can be produced as described above, for example in the form of the stops 9a and 14 arranged on either side of the pump wheel. The magnetic stop with permanent magnet for compensation of axial forces can also be associated with a hydraulic balancing device or with hydrodynamic stops taking up axial forces residual in the event of extreme operation of the motor-driven pump, for example in the case of an absence of pumping fluid.

The hydraulic balancing device can be constituted as shown in FIG. 3 and the hydrodynamic stops can be constituted by the sets of parts 9a and 7b or 14 between which a wedge of pumping fluid under pressure is maintained.

Instead of a permanent magnet stop such as stop 18, an electromagnetic winding stop as shown in FIG. 2b can be used. Such a stop comprises an assembly arranged in a part of the pump body consisting of a cylinder head 18'a made of soft iron or of magnetic material with high permeability and a winding 18'b housed in the cylinder head 18'a as well as a collar 18 'c in soft iron or magnetic material with high permeability housed in the pump impeller. The coil (s) 18'b housed in the cylinder head 18'a are supplied via a control and supply device 46 which optionally receives from a position sensor 47, a position signal representative of the position instantaneous collar 18 ′ c secured to the rotating part of the motor-driven pump with respect to the fixed part of the stop. The supply of electric current to the coil 18'b creates a magnetic field, so that a magnetic flux circulates in the cylinder head and the collar, around the winding, according to the thick arrows shown in FIG. 2B. The attractive force exerted on the rotating part of the motor pump by the fixed part of the stop makes it possible to exactly compensate the hydraulic and magnetic forces exerted on the rotating part of the motor pump, at all times.

However, the use of an electromagnetic stop has certain drawbacks.

It is necessary to provide servo electronics which can be expensive, this servo electronics comprising, as shown in FIG. 2B, the control unit 46 and possibly the position sensor 47. In addition, it is necessary to carry out wiring between a supply terminal box and the coil of the electromagnetic stop on the front face of the stop, which can have drawbacks in an explosive atmosphere. In addition, the supply of the electromagnetic stop results in a loss of efficiency of the motor pump which can be of the order of 4 points.

One of the advantages of the electromagnetic stop is that it can be used without being associated with a complementary system of mechanical and hydraulic stops.

However, it is preferable to combine the electromagnetic stop, either with two mechanical stops, or with a hydraulic balancing system or two hydrodynamic stops, as in the case of permanent magnet stops, so as to take up the residual axial forces in extreme operation of the motor pump, for example in the case of an absence of pumping fluid.

The magnetic parts of the stops, whether permanent magnet or electromagnetic type, are protected by sheets, as are the permanent magnets of the synchronous motor driving the pump rotor.

These protective sheets will be made either of austenitic stainless steel or of a nickel alloy, these materials having been retained because of their non-magnetism, electrical resistivity and weldability properties.

Protection could also be provided by a coating of organic or plastic material on the magnets or other magnetic parts of the stops and of the motor rotor.

As explained above, the choice of material for the protective plate 17a of the stator windings is much wider, these protective plates being able to be fixed without welding in the body of the pump.

In order to favor the evacuation of the heat released by the windings of the stator 17, the cavities of the flange 2b of the pump body in which these windings are housed can be filled with an iso- lant having good thermal conductivity in which the windings are embedded. This coating of the windings also ensures the support of the plate 17a for protecting the windings of the stator 17 and limits the volume of air trapped in the casing of the motor-driven pump. The coating material, for example a resin, makes it possible to meet the standards applicable to equipment intended to be installed in areas where it is feared of explosions.

The motor-driven pump according to the invention, which includes magnetic-type stop elements on the impeller and the pump body, these elements being able to be associated with mechanical or hydrodynamic stops, makes it possible to solve the problem of axial balancing of the rotating assembly of the motor-driven pump in the presence of hydraulic and magnetic forces acting on this rotating part.

In the case where only a hydraulic balancing device is used, this device can only function correctly when the speed of rotation of the pump is sufficient and generally when this speed is at least equal to 75 to 80% of the speed. nominal. It is only from this minimum speed of rotation that the rotor can be detached, undergoing a magnetic attraction independent of the speed of rotation of the pump, by hydraulic forces. In the absence of a magnetic stop, it is therefore not possible to use the power electronics to control the pump at variable speed, and in particular at low speed.

As can be seen in FIG. 4 relating to a second embodiment of the motor-driven pump, it is possible to use a pump wheel 20 comprising rotor elements 21 and 21 ′, for example constituted by permanent magnets, placed on two opposite faces of the pump impeller 20 perpendicular to the axis of rotation of the pump. As before, the rotor elements 21 and 21 ′ are distributed along the entire circumference of the impeller 20 of the pump. Two stators 22 and 22 ′ are then used, housed respectively in the front flange 2a and in the rear flange 2b of the body 2 of the pump, the rotor elements 21 and 21 ′ being opposite respectively the stator elements 22 and 22 '. Apart from the use of a double rotor and two stators, the structure of the pump according to the second embodiment is identical to the structure of the pump according to the first embodiment.

In particular, the axial balancing of the rotating part of the pump constituted by the pump wheel and the rotor is ensured by magnetic type stops. In the case of the embodiment shown in Figure 4, we will use two sets of magnetic stops arranged on either side of the rotor.

Indeed, the attraction exerted on the double rotor by the stator elements 22 and 22 'in the axial direction, in both directions, does not allow a sufficiently stable balancing to be obtained during the operation of the pump.

The rotor elements 21 and 21 ', placed on the opposite faces of the impeller, are arranged on either side of the fluid flow flowing inside the channels 13 of the pump impeller.

The second embodiment of the pump makes it possible to increase the power of the pump by carrying out the drive by two electric motors in parallel.

As can be seen in FIG. 5 relating to a third embodiment of the pump, it is possible, in the case of an embodiment comprising two rotors integrated into the pump wheel similar to the rotors constituted by the elements 21 and 21 ' of the second embodiment and two stators similar to the stators 22 and 22 'of the second embodiment, of providing a double central supply to the pump impeller which includes two openings 24 and 24' open on either side of the wheel, of axial direction, which are extended by pairs of channels symmetrical with respect to a transverse plane of the motor, of trace 27 in FIG. 3, which meet in the form of a single channel 26 of radial direction.

In this case, the pump body has two fluid inlet openings 25 and 25 'axially aligned and each opening into a hole 24, 24' of the pump wheel 23. It is thus possible to double the flow rate of the pump. In this case also the pump must include magnetic stops for axial balancing of the pump impeller. Instead of a single pump wheel, the motor pump according to the invention can comprise several pump wheels fixed on the same shaft or on at least two different shafts and for example two pump wheels, as in the case of the fourth mode of embodiment of the motor-pump shown in FIG. 6, of the fifth embodiment of the motor-pump represented in FIG. 7 and of the sixth embodiment of FIG. 8.

The pump wheels arranged successively in the axial direction of the motor pump and the corresponding parts of the cavity of the pump body constitute successive pumping stages.

In the case of the fourth embodiment shown in FIG. 6, the pump body 2 comprises, in addition to a front flange 2a, a rear flange 2b and a side wall element 2c, two closure plates rear 2d and 2'd. Between these various elements constituting the pump body which are assembled together, there are interposed static seals making it possible to ensure a tight closure of the pump body which comprises two successive cavities 28 and 28 'constituting respectively, with a first pump wheel 30 and with a second pump wheel 30 ′, two successive stages of the pump. The first pump wheel 30 and the second pump wheel 30 'are fixed on the same shaft 31 having the axis 3 of the pump as its axis.

The first pump wheel 30 and the second pump wheel 30 ′ have, at their central part, an inlet port for substantially axial direction fluid and a plurality of channels connected to the outlet for the pump wheel, direction substantially radial.

Rotor elements such as permanent magnets 32 are integrated into the second pump wheel 30 'and placed in a lateral face of the pump wheel 30' perpendicular to the axis 3 of the pump, in a circumferential arrangement. The rotor elements 32, integrated into the second pump wheel 30 ', are placed in the rear lateral face of the pump wheel 30', opposite a stator 35 mounted in the rear flange 2b of the body pump. In addition, the rear flange 2b of the pump body 2 is crossed by the fluid outlet pipe 5, in a radial direction and by a channel for the passage of the stator supply cables 35.

No rotor element is integrated into the first pump wheel 30 which has only a hydraulic role. The wheels 30 and 30 ′ and the shaft 31 of the pump are driven in rotation by the motor constituted by the rotor elements 32 and the stator 35.

The bearings of the rotating assembly constituted by the first pump wheel 30, the second pump wheel 30 'and the shaft 31 are carried, respectively, by the front flange 2a and the first pump wheel 30 and by the closing plate 2'd and the rear part of the shaft 31. Magnetic stop elements are fixed on the pump impeller 30 'and on a part opposite the pump body 2.

The side wall element 2c of the pump body 2 has two transverse walls 33 and 33 ′ delimiting a fluid outlet space from the first stage of the pump constituted by the cavity 28 and the impeller 30 and a passage for guiding the fluid to the inlet of the second stage of the pump constituted by the second impeller 30 'and the cavity 28'. The wall 33 has at least one opening 34 for the passage of the fluid leaving the first stage of the pump.

The use of two successive pumping stages makes it possible to increase the pressure of the fluid in the second cavity of the pump body 28 ′ and in the outlet channel 5 of the pump.

In the case of the fifth embodiment shown in FIG. 7, the motor pump according to the invention comprises two pump wheels 36 and 36 ', in each of which are integrated rotor elements 37 and 37', such as permanent magnets, placed in transverse faces of the wheels 36 and 36 'facing stators 38 and 38' mounted in the pump body as well as magnetic abutment elements facing corresponding elements carried by the pump body.

The pump body 2 comprises a front flange 2a, a first rear flange 2b, a second rear flange 2'b, a lateral closing element 2c and two rear closing plates 2d and 2'd. Between the successive elements of the pump body, which are assembled together, are interposed static O-rings.

The first stator 38, disposed opposite the rotor elements 37 of the first pump wheel 36, is fixed to the first rear flange 2b. The elements of the stator 38 ', arranged opposite the rotor elements 37' integrated into the second pump wheel 36 ', are fixed in cavities of the second rear flange 2'b of the pump body.

Radial parts of the first rear flange 2b and of the transverse closure element 2c of the pump body define a path for circulation of the fluid which is pumped, between a first pumping stage constituted by the first impeller 36 and by a first cavity 39 of the pump body and the second pumping stage constituted by the second pump impeller 36 'and by a second pumping cavity 39' of the pump body communicating with the radial outlet 5 of the pump. The radial part delimiting the passage of fluid from the first rear flange 2b is pierced with an opening for axial passage of the fluid which is pumped.

The mobile pump assembly, consisting of the first pump wheel 36, the second pump wheel 36 'and a shaft 41 on which the pump wheels 36 and 36' are fixed, is rotatably mounted in the body of the pump. pump 2 and driven in rotation by the first electric motor constituted by the stator 38 and the rotor elements 37 and by the second electric motor constituted by the second stator 38 'and the second rotor elements 37'.

The pumping or compression pressure of the fluid can be increased by successive passages in the first pumping stage and in the second pumping stage.

In Figure 8, there is shown a sixth embodiment of a motor pump according to the invention. The corresponding elements in Figures 7 and 8 are assigned the same references. The only difference between the motor pumps according to the fifth and sixth embodiments is that, in the case of the fifth embodiment, the two pump wheels 36 and 36 'are fixed respectively, on independent shafts 41 and 41' mounted rotating through two bearings in the pump body 2 and rete- axially naked, each by an assembly with axial stops comprising magnetic elements such as magnets or coils. Thanks to this mounting with independent shafts (or any other independent rotary mounting in the pump body), the two pump wheels 36 and 36 ′ can turn at different speeds and independently adjustable from one of the other. In particular, the independent adjustment of the speed of the wheel 36 of the input stage of the pump makes it possible to adjust the cavitation effect. The motor pump can include any number of wheels mounted to rotate independently of one another in the pump body, at least one of the wheels carrying at least one rotor element placed opposite a stator. carried by the pump body and at least one magnetic abutment element opposite a magnetic element integral with the pump body.

For all the embodiments described, the total size of the pump is reduced by the fact that the rotor (s) of the electric motor (s) driving the pump are integrated into one or more wheels of the pump. .

Hydraulic friction losses are also reduced, since the same rotating part can constitute a pump wheel and a rotor. The axial balancing of the rotating part of the pump is always ensured by magnetic stops associated either with mechanical stops, or with hydro-mechanical stops, or even with a hydraulic balancing device similar to the device shown in FIG. 3.

Generally, the magnetic stops are placed opposite the pump drive rotor (s).

The number of parts to be manufactured for the realization of the pump is also reduced. Not only the size and the weight of the pump but also the cost thereof can be reduced thanks to the arrangement according to the invention. The invention is not limited to the embodiments which have been described.

This is how the number of successive wheels and pumping stages can be any, depending on the expected characteristics of the pump. Each of the successive stages of the pump can comprise a pump wheel fitted with rotor elements or a pump wheel not comprising rotor elements, at least one of the stages of the pump comprising however a pump wheel in which are integrated with rotor elements arranged opposite a stator carried by the pump body. The pump wheels can be produced in modular form and optionally assembled with a modular rotor component integrating the rotor elements. The modular element of the pump impeller and the modular rotor component are assembled face to face, so that the modular rotor component has a transverse face perpendicular to the axis of rotation of the pump impeller.

The pump wheels can also be produced in a single piece and include cavities for housing and fixing the rotor elements. The invention applies to the pumping or compression of any fluid in a centrifugal pump or compressor having a sealed body.

Claims

WO-OO / 37804 PCT / FR99 / 03241

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CLAIMS 1.- Motorized device with centrifugal circulation of a fluid, such as a motor pump or a motor-compressor, comprising a sealed body (2) and at least one wheel (10, 20, 23, 30, 30 ', 36 , 36 ') rotatably mounted around an axis of rotation (3) in the sealed body (2) comprising at least one fluid inlet (4, 24, 24') at its central part and a plurality of channels (13, 26) for circulation of fluid in a substantially radial direction, between the central fluid inlet (4, 24, 24 ') and the periphery of the wheel (10, 20, 23, 30, 30', 36, 36 ') as well an electric motor for driving the wheel comprising a stator (17, 22, 22 ', 35, 38, 38') and a rotor integral in rotation with the wheel, characterized by the fact:

- that the rotor (16, 21, 21 ', 32, 37, 37') produced in discoid form is integrated into the wheel (10, 20, 23, 30, 30 ', 36, 36') and arranged in screw- with respect to at least one element of the stator (17, 22, 22 ', 35, 38, 38') fixed in the watertight body (2) of the device, and.

- that the wheel (10, 20, 23, 30, 30 ', 36, 36') bears on at least one lateral face facing a part of the sealed body (2), at least one magnetic element (18c, 18'c) placed opposite a corresponding magnetic element (18a, 18'a, 18b, 18'b) integral with the part of the sealed body (2) to constitute at least one stop exerting on the wheel a force of magnetic origin of axial direction.

2.- Device according to claim 1, characterized in that one of the elements (18a, 18b) of the magnetic stop for axial balancing of the rotor comprises at least one permanent magnet (18b).

3.- Device according to claim 1, characterized in that one of the magnetic elements (18'a, 18'b) of the magnetic stop for axial balancing of the rotor comprises at least one coil (18'b), the stop being an electromagnetic stop controlled according to a signal from a wheel position sensor (47) (10, 20, 23, 30, 30 ', 36, 36') of the device.

4.- Device according to any one of claims 1, 2 and 3, characterized in that it further comprises two mechanical stops (9a, 7b, 14) for axial retention of the wheel (10) and the rotor ( 16), in a first direction and in a second direction, arranged on either side of the tour- nante of the device constituted by the wheel (10, 20, 23, 30, 30 ', 36, 36') and the rotor (16) integrated into the wheel.

5.- Device according to any one of claims 1 to 3, characterized in that it further comprises two hydrodynamic stops (9a, 7b, 14) for axial retention of the rotating part of the device constituted by the pump wheel (10, 20, 23, 30, 30 ', 36, 36') and the rotor (16), in a first direction and in a second direction, arranged on either side of the rotating part of the device, each of hydrodynamic stops comprising a fixed rotating part and a rotating part separated from each other by pumping fluid.

6.- Device according to any one of claims 1 to 3, characterized in that it further comprises a hydraulic balancing device comprising an outer rolling space (42) between an outer part, that is to say -display away from the axis (3) of the rotor (16) and a part (2a) of the pump body (2) communicating with a delivery part (13) of the pump impeller and an interior rolling space (44 ) between an inner part, that is to say disposed towards the axis (3) of the rotor (16) and a part (2b) of the pump body (2), communicating with a suction part of the impeller pump (10), the outer fluid rolling space (42) and the inner fluid rolling space (44) being delimited between surfaces of the rotor (16) and parts (2a and 2b) of the body pump, respectively, substantially perpendicular to the axis of rotation (3) of the wheel (10) in the sealed body (2).

7.- Device according to any one of claims 1 to 6, characterized in that the stator (17) comprises, inside cavities of a part (2b) of the sealed body (2) of the device , embedded windings, coated in a material such as a resin.

8.- Device according to claim 7, characterized in that the cavities of the part (2b) of the sealed body (2) in which are fixed the stator windings (17) are closed on a face opposite of the rotor (16) by a protective plate (17a) fixed in the sealed body (2) by clamping between two parts (2a, 2b) of the sealed body (2).

9.- Device according to any one of claims 1 to 8, characterized in that it comprises a plurality of rotor elements constituted by at least one of the following elements: permanent magnets, coils, salient poles, distributed along the circumference of the wheel (10, 20, 23, 30, 30 ', 36, 36'), the stator (17) being constituted by a plurality of coils placed opposite the plurality of elements rotor.

10.- Device according to any one of claims 1 to 9, characterized in that it comprises a single wheel (10) having a single fluid inlet (4) on one side of one of the side faces of the wheel (10) or entry face of the wheel and at least one rotor element (16b) integrated into the wheel (10) on the side face of the wheel opposite the entry face.

11.- Device according to any one of claims 1 to 9, characterized in that it comprises a single wheel (20) having a single fluid inlet on the side of the entry side face of the wheel (20) and at least one rotor element (21, 21 ') on each of the side faces of the wheel opposite the stator elements (22, 22').

12.- Device according to any one of claims 1 to 9, characterized in that it comprises a single wheel (23) having two fluid inlets (24, 24 ') at its central part on the side of a first side face of the wheel and on the side of a second face opposite to the first and at least one rotor element on each of the side faces of the wheel opposite at least one stator element carried by the body (2) of the device.

13.- Device according to any one of claims 1 to 9, characterized in that it comprises at least two wheels (30, 30 ') successively fixed in the axial direction (3) on a shaft (31) rotatably mounted in the pump body (2), at least one of the pump wheels (30 ') comprising at least one rotor element (32) integrated into the impeller (30') on at least one side face of the wheel (30 ') and arranged opposite at least one stator element (35).

14.- Device according to claim 13, characterized in that it comprises at least two wheels (36, 36 ') successively fixed in the axial direction (3) of the pump on a shaft (41) rotatably mounted in the body pump (2), at least one rotor element (37, 37 ') being integrated in each WO-ΘO / 37804 PCT / FR99 / 03241

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one of the wheels (36, 36 '), on at least one lateral face of each of the wheels (36, 36') and arranged opposite at least one stator element (38, 38 ').

15.- Device according to any one of claims 1 to 9, characterized in that it comprises at least two wheels (36, 36 ') rotatably mounted independently of one another, in the pump body ( 2), at least one of the wheels (36, 36 ') carrying at least one rotor element (37, 37') placed opposite a stator (38, 38 ') carried by the body pump (2).