WO2003098778A1

WO2003098778A1 - Electric motor for use as a pump motor and corresponding pump

Info

Publication number: WO2003098778A1
Application number: PCT/EP2003/003748
Authority: WO
Inventors: Hans-Joachim Wysk
Original assignee: Minebea Co., Ltd.
Priority date: 2002-05-16
Filing date: 2003-04-10
Publication date: 2003-11-27
Also published as: DE10221843A1; EP1504514A1; JP2005526475A; AU2003227603A1; DE10221843B4

Abstract

The invention relates to a pump comprising an electric motor which is used as a pump motor. The electric motor comprises a stator, provided with at least one winding, an external rotor enclosing the stator, and a hub that is non-rotationally linked with the external rotor and that is provided with an impeller wheel. The external rotor and the hub are rotationally mounted via a bearing unit on a shaft that holds the stator. Said bearing unit comprises an impeller wheel proximal first bearing and an impeller wheel distal second bearing. The electric motor is associated with a motor housing that forms part of the hub and that is configured in such a manner that it encapsulates, together with the impeller wheel, the stator and the external rotor especially in the form of a bottle, thereby sealing them off.

Description

Electric motor for use as a pump motor and pump

The invention relates to an electric motor, in particular an external rotor motor, for use as a pump motor.

Electric motors, especially external rotor motors, are used in various technical areas. One application is to drive a pump for conveying fluids, in particular liquids, with an electric motor. Depending on the type and properties of the fluid to be delivered, it can be provided that the components of the electric motor come into contact with it or that contact between the components of the electric motor and the fluid is to be prevented, for example because it is aggressive, corrosive Fluids that attack individual engine components and can shorten their lifespan, or because contamination of highly sensitive fluids should be avoided.

FIG. 11 shows a longitudinal sectional view of a pump with an electric motor according to the prior art, in which the fluid to be pumped cannot come into contact with the electrically active components of the electric motor. The pump according to FIG. 11 is generally designated with the reference symbol 10 'and is designed as a radial pump, ie the fluid to be pumped flows into a pump inlet according to arrow Pi and flows radially out of pump 10' according to arrow P ₂ . The pump 10 'is provided with an impeller wheel 12' which has flow channels directed radially outwards. The impeller wheel 12 'is mounted on a shaft 14'. The shaft 14 'is rotatably mounted in a housing 20' via a bearing arrangement with a first ball bearing 16 'and a second ball bearing 18'. A ring 22 'made of soft magnetic material, which carries rotor magnets 24' on its outer circumference, is also attached in a rotationally fixed manner to the shaft 14 '. The ring 22 'and the rotor magnets 24' form the rotor 26 'mounted on the shaft 14'. A stator 28 'is arranged around the rotor 26' and comprises a laminated core 30 'and windings 32'. The stator 28 'is rotationally fixed to the housing 20' and a pot 34 'connected to it. When the windings 32 'are normally excited, the rotor 26' rotates within the stator 28 'and thus drives the shaft 14' which is rotatably mounted in the housing 20 'via the bearings 16', 18 '. In this case, the impeller wheel 12 'is also driven, so that it presses the fluid located in its delivery channels outwards in accordance with arrow P ₃ due to the centrifugal force generated during rotation. A vacuum is created on the suction side at arrow Pi, whereas an overpressure is created on the pressure side at arrow P ₂ , which leads to a conveying movement of the fluid.

The known pump described with reference to FIG. 1 1 has considerable disadvantages. On the one hand, it is relatively difficult to prevent the fluid to be conveyed from penetrating into the region of the impeller wheel 12 'via the bearings 16', 18 'to the electrically active components of the motor. For this purpose, elaborate precautions have been taken in the motor shown, for example a labyrinth-like design of the impeller wheel 12 'on the side facing the housing 20', such that two ring projections engage in corresponding ring grooves and thus form a labyrinth seal. In addition, the bearing 16 'is provided on its side facing the impeller wheel 12' with a sealing ring 36 '. Despite these precautions, due to the high pressure generated by the impeller wheel 12 ', it cannot be prevented that fluid to be conveyed penetrates through the labyrinth seal and the ring seal 36' arranged between the rotating shaft 14 'and the fixed housing 20' and into the region of electrically active components. This can lead to corrosion formation on the components of the electric drive, particularly in the case of aggressive fluids to be pumped, and under certain circumstances even result in failure of the electric motor. In addition, the spatial separation of the electrically active components, in particular the stator 28 'and the rotor 26', from the fluid-conveying components, in particular from the impeller wheel 12 ', leads to a relatively large-volume structure of the pump 10', which is suitable for various applications in which one small volume light pump is required, can be disadvantageous. The large-volume design of the pump 10 'is due not least to the fact that the electric motor is constructed according to the internal rotor principle, ie with a rotating shaft, which is both a complex bearing with two ball bearings 16' and 18 'and a relatively complicated structure Stator especially with regard to the arrangement of the windings as a pull-in winding requires. A pump similar construction, as described above, is also known from DE 199 43 862. However, in this pump only the electrically active parts of the motor drive are encapsulated by the fluid to be pumped, whereas the fluid to be pumped comes into contact with the rotor designed as an internal rotor. On the one hand, this configuration has the disadvantage that the rotor rotating in the fluid to be conveyed has to perform "flexing work", so that so-called splashing or splashing losses can occur, that is to say losses which arise due to the fluid dynamic resistance caused by the fluid to be conveyed arise. In addition, in this known pump to prevent contact of the fluid to be delivered with the electrically active parts of the stator, it is necessary to provide a partition between the rotor and the stator. However, this means that the magnetic gap between the rotor and the stator has to be increased, which in turn lowers the magnetic induction B and thus reduces the motor efficiency. Finally, depending on the fluid to be pumped, there may also be corrosion effects on the rotor around which the fluid to be pumped flows and thus a shortening of the service life of the motor drive.

Also in the solution shown in DE 100 25 190 AI, the rotor designed as an internal rotor comes into contact with the fluid to be conveyed, so that the above-mentioned adverse effects, such as splashing losses, reduction in motor efficiency due to an increase in the magnetic gap, and risk of corrosion can occur ,

Furthermore, DE 100 24 953 AI shows a pump similar structure, in which the fluid to be pumped can also penetrate into the area of the motor drive.

In contrast to the motor or pump variants according to the prior art discussed above, DE 36 35 297 shows a motor variant which is designed as an external rotor motor. In this motor variant, a rotor designed as a ring rotates around a stator which is mounted on a fixed shaft in a rotationally fixed manner. In addition, a cooling fluid is provided in the area of the rotor and stator for cooling in this external rotor motor.

Also in the pump according to DE 199 48 972 AI, an outer rotor, a hub connected to it and a pump wheel rotate about a shaft, the corresponding bearing arrangement being a comprises a first bearing close to the pump wheel and a second bearing remote from the pump wheel. A thin separate sleeve is used to separate the stator space from the rotor space.

The pumps described in DE 44 11 960 C2 and US 2001/0033800 AI have a similar arrangement.

Finally, DE 26 55 317 indicates the use of an external rotor motor with a compressor blade.

It is an object of the present invention to provide an electric motor for use as a pump motor and a corresponding pump which, with high motor efficiency and a simple, small-volume design, enables use regardless of influences and properties of the fluid to be conveyed.

This object is achieved by an electric motor, in particular an external rotor motor, for use as a pump motor, with a stator provided with at least one winding, an external rotor encompassing the stator, and a hub connected non-rotatably to the external rotor, which is provided with a pump wheel or a special impeller wheel is, wherein the outer rotor and the hub are rotatably mounted on a shaft or shaft holding the stator by means of a bearing arrangement, the bearing arrangement comprises a first bearing near the pump wheel and a second bearing remote from the pump wheel, and a motor housing is assigned to the motor, which forms part of the hub and which is designed such that it encapsulates the stator and the outer rotor in a sealed manner together with the pump wheel. The motor housing can have a bottle shape, and a radial and axial seal can be provided on the bottle neck.

The design of the electric motor as an external rotor motor enables a relatively compact design of the motor. By encapsulating the stator and outer rotor in the motor housing, contact of the fluid to be delivered with the electrically active parts of the stator and outer rotor can be effectively prevented, despite the relatively small-volume construction. This makes it possible to use the electric motor in a pump with which aggressive media or highly sensitive media can be pumped. With regard to the encapsulation of the stator and outer rotor in the hub, it can be provided that the motor housing forms a first hub part and the pump wheel forms a second hub part. As a result, the hub is produced in a shell-like manner from two hub parts, namely from the motor housing and the pump wheel, so that the encapsulation can be achieved effectively using parts that are required anyway, and at the same time a reduction in the size of the motor, a reduction in the number of parts and thus associated cost reductions are possible. In this embodiment of the invention it can be provided that the motor housing is flanged to the pump impeller in a sealing manner. For example, corresponding end faces of the motor housing and pump wheel can be connected to one another by gluing or pressing. Alternatively, it can be provided that the motor housing is accommodated in the pump wheel in a sealing manner. For this purpose, it is necessary to provide an annular groove or an annular projection in the pump wheel, which is used to hold the motor housing.

To produce a magnetic yoke on the outer rotor, it is possible to manufacture the motor housing from a soft magnetic material. The motor housing itself thus acts as a yoke for producing the magnetic yoke, so that no additional component has to be provided between the motor housing and the rotor. This measure contributes to a further reduction in the number of parts and to a reduction in the construction volume of the electric motor. However, should the formation of the motor housing from a soft magnetic material be unfavorable due to, in particular, corrosive properties of the fluid to be conveyed or for reasons of weight saving, it can alternatively be provided to manufacture the motor housing from a non-magnetic material and a soft magnetic between the outer rotor and the hub Provide yoke. In this embodiment of the invention, the yoke made of soft magnetic material for producing the magnetic yoke can be arranged in the encapsulated area, so that mutual contact between the yoke and the fluid to be conveyed is excluded. The motor housing can then be made, for example, of aluminum or inert plastic material or the like.

In addition to the approaches according to the invention for reducing the number of parts and size of the electric motor already discussed above, it is also possible to take corresponding precautions on the bearing arrangement for this purpose. For example, that first bearings near the pump wheel are designed as plain bearings and are axially secured on the shaft. The use of a plain bearing offers the advantage of a relatively small radial expansion with low weight and thus the possibility of further size reduction. Alternatively, however, it is also possible to design the first bearing as a roller bearing, in particular as a ball bearing. As a result, improved running properties, in particular less friction, and a longer bearing life can be achieved. Regardless of the choice of the bearing as a plain bearing or a rolling bearing, further space can be saved by arranging the first bearing in a bearing receptacle formed in the pump wheel. This saves axial installation space, so that the electric motor can be made more compact.

If the pump wheel is designed as a radial conveying means, to which the fluid to be conveyed flows axially and is conveyed radially outward - that is to say which is also under load in the axial direction - it is necessary to design the bearing arrangement also for absorbing axial forces. For this purpose, this must be braced axially. It makes sense to carry out the axial bracing in particular in the area of the first bearing, because the axial forces act precisely in its vicinity, namely on the pump wheel. For this purpose, in a further development of the invention it can be provided that for the axial bracing of the bearing arrangement between the shaft and the pump wheel, a spring element biased in the axial direction, in particular an elastomer spring element, and a ball acting on the spring element are arranged. The axial forces occurring on the pump wheel are absorbed by the ball bearing arrangement and are transferred to the fixed shaft without play via the ball acting on the spring element. However, other measures for axial bracing are also conceivable, such as, for example, the attachment of disc springs to the first bearing or the like, which can also interact with an axial ring seal between the motor and the housing.

With regard to the second bearing, it can be provided that it is designed as a sliding bearing, in particular as a compact sintered bearing, plastic bearing or ceramic bearing. Such a configuration of the second bearing remote from the pump wheel is particularly useful when the first bearing is designed as a roller bearing and in the region of the first bearing the above-mentioned axial bracing via the prestressed spring element and the ball is provided. For easy assembly and simple arrangement of the second bearing can In a further development of the invention, it is provided that it is received in a bearing receptacle formed in the motor housing.

It has been mentioned several times above that the motor housing, together with the pump wheel, encapsulates the stator and the outer rotor in a sealed manner. Various seals are provided for this purpose, which will be specified in more detail below. Thus, in an embodiment according to the invention, at least one radial seal, in particular at least one mechanical seal or at least one O-ring, can be provided between the shaft and the motor housing in the region of the second bearing. Since this area of the motor housing is located relatively far from the pump wheel and there are at most low fluid pressures, the precautions to be taken in this area are less complex for an adequate seal. As an alternative or in addition to the mechanical seal or O-ring, it can be provided that at least one resiliently preloaded radial / axial seal is arranged between the shaft and the motor housing in the region of the second bearing. Furthermore, alternatively or additionally, it can be provided that at least one return seal, in particular return thread seal, is provided between the shaft and the motor housing in the region of the second bearing. In particular, the return thread can be formed either on the shaft or on the motor housing or on a sealing ring between the shaft and motor housing. The peculiarity of return thread seals lies in the fact that they are arranged essentially in a contactless and therefore friction-free manner between the parts to be sealed to one another, but only seal inadequately in the absence of relative rotation between these parts. In dynamic operation, i.e. with relative rotation between the two parts to be sealed, while avoiding friction losses and the associated undesirable wear and abrasion effects due to the thread of the return thread seal, there is fluid present between the two parts to be sealed via the thread valleys of the return thread seal from the area to be sealed is promoted away. It should be noted that the orientation of the return thread, i.e. training as a right-hand or left-hand thread, which must be coordinated with the direction of rotation in order to achieve a feedback effect.

The design of the electric motor as an external rotor motor with a fixed shaft offers the further advantage of guiding the feed lines for the stator over the shaft. This can can be achieved, for example, in that the shaft is provided with a bore for receiving leads to the stator. This measure ensures that the supply lines and the areas to be sealed can be completely separated from one another and thus the supply lines leave the already complex sealing of parts that are moving relative to one another unaffected. This constructive measure also leads to an inexpensive, solid and compact pump motor design.

The measures according to the invention with regard to the design of the electric motor were analyzed above. As already indicated at the beginning, the invention further relates to a pump for conveying fluids, which is designed with an electric motor of the type described above, the pump having a pump housing receiving the electric motor with an inlet and an outlet for supplying and removing the fluid. In this respect, an integrated motor is created without an additional clutch, bearings, seals and installation space.

Such a pump is suitable, for example, for use in a cooling circuit of a motor vehicle. The use of a pump designed with a separate motor drive has the advantage that the pump can only be switched on when necessary. The pump is therefore not permanently active like a conventional pump driven by the internal combustion engine of the motor vehicle via a toothed belt, but only when cooling is actually required. This can reduce the overall fuel consumption of the vehicle and extend the service life of the pump. This also enables the engine, catalytic converter or auxiliary heater to be preheated.

In this pump, the pump housing can be designed in such a way that only a thin gap is provided between it and the hub. This thin gap can be filled with fluid to be pumped. On the one hand, this makes it possible to achieve a certain level of noise damping, so that the intensity of the drive noise caused by the electric motor and emerging through the pump housing is reduced due to fluidic noise damping. Furthermore, a thin gap filled with fluid offers the further advantage of improved thermal transmission, so that the heat of dissipation generated in the motor in the drive case is more easily transferred from the motor housing or the hub via the liquid to the pump housing and from there to the environment can. In the- In this context, it should be pointed out that in a further development of the invention, the pump housing can additionally be formed with cooling fins on its surface facing away from the hub. This leads to an increase in surface area and to better heat dissipation from the pump housing.

Although, as stated above, a certain entry of leakage fluid into the thin gap between the pump housing and the hub may be desirable, an embodiment variant of the invention can also provide that in a region near the pump wheel on the pump housing and / or on the hub to seal the gap a gap seal, in particular a sealing ring and / or a return thread seal, is arranged. The provision of such a gap seal should at least limit the amount of leakage fluid entering the thin gap between the pump housing and the hub and thus avoid an undesirably high loss of the fluid to be delivered due to leakage. With regard to the use of a return thread seal, it should be noted that in dynamic operation, i.e. when the pump wheel rotates, the hub rotates relative to the pump housing at the speed of the pump wheel, so that the return thread seal provided on it can develop its effect precisely when high pressures occur on the pressure side of the pump. In dynamic operation, it is thus possible to effectively prevent these high pressures from spreading into the thin gap between the pump housing and the hub due to the fluid return effect of the return thread seal. In the static case, i.e. When the pump is not in operation, the pressure of the fluid to be pumped is relatively low, so that the leakage fluid entering the thin gap between the pump housing and the hub can penetrate the second bearing only at low pressure and penetrate the second bearing with relatively simple precautions leakage fluid to the motor components outer rotor and stator can be prevented.

In order to further curb such penetration of leakage fluid to the second bearing, it can be provided in one embodiment of the invention that in a region of the hub remote from the pump wheel, a further gap seal is provided to seal the gap. This second gap seal can comprise a labyrinth seal and / or a ring seal, in particular an O-ring, and / or a thread return seal. When using a thread return seal, it can be provided that it has a thread pitch oriented in the axial and / or in the radial direction. forms is. For this purpose, various surfaces of the motor housing can be provided with thread formations at contour stages and can be used to further improve the sealing effect of the return thread seal.

In order to prevent leakage fluid which has penetrated into the thin gap despite further at least one of the seals described above, in a further development of the invention it can be provided that the gap with an overflow for removing excess fluid - or also for Return to the fluid circuit - is connected.

For electronic monitoring of pump operation and for controlling the drive of the electric motor integrated in the pump, it can be provided in a development of the invention that at least one first sensor component is provided on the hub and at least one second sensor component is provided on the pump housing, the first sensor component and the second sensor component allow detection of a relative rotation of the hub relative to the housing. Such a sensor system consisting of the two sensor components can be accommodated in a region of the pump remote from the pump wheel with relatively little effort.

Although radial pumps have been discussed above in relation to the prior art, this is not intended to imply that the pump according to the invention is exclusively a radial pump. Rather, the pump according to the invention can either be designed as a radial pump, in which the fluid to be delivered is discharged in the radial direction, or as an axial pump, in which the fluid to be delivered is discharged in the axial direction.

The invention is explained below by way of example with reference to the accompanying figures. They represent:

FIG. 1 shows a longitudinal sectional view of a first exemplary embodiment of a pump according to the invention;

Figure 2 is an exploded view of the pump shown in Figure 1; FIG. 3 shows an exploded view of the pump motor used in the pump according to FIG. 1;

FIG. 4 shows a longitudinal sectional view of a second exemplary embodiment of a pump according to the invention;

Figure 5 is a longitudinal sectional view of a third embodiment of a pump according to the invention;

Figure 6 is a longitudinal sectional view of a fourth embodiment of a pump according to the invention;

Figure 7 is a longitudinal sectional view of a fifth embodiment of a pump according to the invention;

Figure 8 is a longitudinal sectional view of a sixth embodiment of a pump according to the invention;

FIG. 9 shows a longitudinal sectional view of a sixth exemplary embodiment of a pump according to the invention;

Figure 10 is a cross-sectional view of the pump of Figure 9 and

Figure 11 is a longitudinal sectional view of a pump according to the prior art.

1 to 3 show a first exemplary embodiment of a pump according to the invention, which is designated by 10. The pump 10 comprises a pump housing 12, which consists of a first housing part 14 and a second housing part 16. A pump motor 18 is accommodated in the pump housing 12, on the left end of which is formed in FIGS. 1 and 2 a pump wheel or special impeller wheel 20. Channels 22 are provided in the impeller wheel 20, which open in a radially inner region at 24 in the direction of a longitudinal axis A and which open in a radially outer region at 26 with respect to the longitudinal axis A in a substantially radial direction.

An annular projection 28 is formed on a side of the impeller wheel 20 facing away from the axial opening 24. Furthermore, the impeller wheel 20 has on this side a radially inner ring projection 30, in which a ball bearing 32 is received in a form-fitting manner. A recess 34 with a stepped diameter is formed radially inside the ring projection 30, and an elastomeric spring element 36 is inserted in the deepest region thereof. The recess 34 serves to receive a shaft 38 of the motor 10.

A laminated core 40, which is provided with windings 42, is fixed on the shaft 38. The windings 42 can be controlled electrically via supply lines 44, the supply lines 44 being able to be sensed through the shaft 38 via a radial bore and an axial bore 46 communicating therewith. The feed lines 44 are fixed in the axial bore 46, for example, by means of a cast-in and hardened synthetic resin material.

A pot-like motor housing 48 is formed on the right-hand side in FIGS. 1 to 3. In the interior of the motor housing 48, a magnetic ring 50 serving as an outer rotor with individual magnetic elements which follow one another in the circumferential direction is attached in a rotationally fixed manner. At the right end in FIGS. 1 to 3 of the motor housing 48, this is formed with a diameter step 52 which serves as a receptacle for a plain bearing bush 54.

When assembling the pump motor shown in FIG. 3 in an exploded view, the shaft 38 is inserted into the recess 34, so that the impeller wheel 20 is rotatably supported on the shaft 38 about the axis A via the ball bearing 32. Furthermore, the motor housing 48 is placed on the ring projection 28 by passing the leads 44 through the bearing bush 54 and by inserting the right end of the shaft 38 in FIG. 3 into the bearing bush 54, so that the area of the motor housing 48 on the left in FIG engages radially outer region of the ring projection 28. The diameter of the annular projection 28 and the motor housing 48 are coordinated with one another in the interacting regions. After this Put on the impeller wheel 20 on its ring projection 28 with the motor housing 48, for example by gluing or the like. Sealed.

It should be pointed out that for the axial bracing of the bearing 32, a ball 56 is inserted between the left end of the shaft 38 and the elastomeric spring element 36 and engages in a cylindrical recess 58 in the shaft 38. The ball 46 together with the elastomeric spring element 36 ensures that the shaft 38 is prestressed to the right in the direction in FIGS. 1-3 and that axial loads acting on the impeller wheel 20 can thus be transferred to the shaft 38 without play via the bearing 32.

A sealing ring 60 and an external threaded ring 62 are then placed on the pump motor 18 assembled in this way in an area near the impeller wheel, as shown in FIG. 2. Furthermore, a sealing bush 64 is placed on the reduced-diameter area 52 of the motor housing 48. The sealing bushing 64, as can be seen in particular from the enlarged illustration according to FIG. 1, is provided with thread formations on its sides facing the second housing part 16. Furthermore, a thread formation is also formed in the surface of the threaded bushing 64 facing the shaft 38. The mode of operation of these thread formations will be discussed in detail later.

Turning to the housing 12, it can be seen from FIG. 2 that the first housing part 14 has an axial opening 66 through which fluid can flow. Starting from this axial opening 66, it extends rounded radially outwards, where it forms a trough 68 which runs around the axis A in the circumferential direction and ends in a flange 70. The trough 68 has a round contour with an inner radius r that changes continuously in the circumferential direction.

The second housing part 16 is also cup-shaped and has a stepped interior 72. Cooling fins 74 are provided on its outer surface, which increase the surface effective for heat dissipation in the area receiving the electric motor 18. The cooling fins 74 run out in a trough 76 running in the circumferential direction about the axis A, which in turn runs out into a flange 78. The trough 76 also has a round contour with an inner radius p that changes continuously in the circumferential direction on. In the area of the largest inner radius p, an outlet connection 80 is provided on the tub 76.

For further assembly of the pump 10, the electric motor with its shaft 38, as shown in FIG. 2, is inserted into the stepped interior 72 of the second housing part 16, so that the shaft 38 in the smallest diameter part of the cavity 72 and the sealing bush 64 in the area of the cavity 72 engages with the next larger diameter. On the impeller wheel side, the first housing part 14 is then applied with its flange 70 to the flange 78 of the housing part 16 and connected to the latter via connecting means, such as screws, rivets, or by gluing. As a result, the two troughs 68 and 76 define a channel 82 extending in the circumferential direction about the axis A, the trough diameters r and p being selected such that the cross-sectional area of the channel 82 increases continuously in the direction of rotation of the impeller wheel 20 toward the outlet connection 80. During operation it can thereby be achieved that fluid conveyed through the impeller wheel 20 into the channel 82 is pressed towards the outlet connection 80.

After such an assembly of the pump 10, it has the shape as shown in FIG. 1 in longitudinal section. The following features are particularly noteworthy in this construction. The components of the electric motor 18, namely the magnetic ring 50 as well as the laminated core 40 and windings 42, are accommodated within the pot-like motor housing 48 and are encapsulated from the environment by the tight connection of the motor housing 48 and impeller wheel 20. With this design of the electric motor 18, it is possible to provide a very narrow magnetic gap S between the inner circumferential surface of the magnetic ring 50 and the outer circumferential surface of the laminated core 40, as a result of which the magnetic induction B increases in the gap and ultimately the motor efficiency can be increased. This design of the pump electric motor 18 also offers some advantages over the pump described above according to DE 199 43 862 AI, because due to the elimination of the generally metallic containment shell from the magnetic motor air gap, which are possible due to the invention, very small air gaps can be realized, which one cause high engine efficiency. In addition, the eddy current losses occurring there are minimized. Furthermore, protective armor caps around the magnets, which also require a large amount of space, are unnecessary insofar as the magnetic ring rotates inside the return cup and is therefore less sensitive to the centrifugal forces acting on it. In the embodiment shown in FIGS. 1 to 3, the motor housing 48 is made of a soft magnetic material, so that it can form the magnetic yoke to the magnetic ring 50.

The second housing part 16 receives the pump motor 18 with a likewise relatively thin gap R between the inner surface delimiting the cavity 72 and the outer surface of the motor housing 48. In order to seal this gap R with respect to the areas of the pump 10 near the impeller wheel intended for the fluid delivery, the sealing ring 60 and the external threaded ring 62 are provided. The sealing ring 60 provides a static seal by being in contact with both the motor housing 48 and the inner surface of the second housing part 16. The external threaded ring 62 has only a dynamic sealing effect, namely in such a way that, when the motor housing 48 and thus the external threaded ring 62 rotate, the thread formation formed there creates flow effects in the valleys of the threaded formation, the fluid contained therein from the gap R to the impeller wheel promote. In the static case, i.e. when the motor housing 48 is at a standstill relative to the pump housing 12, the external threaded ring 62 has hardly any sealing effect, since it does not touch the surface section of the second housing part 16 lying opposite it.

Despite the sealing ring 60 and the external threaded ring 62, when fluid is conveyed via the impeller wheel 20, due to the relatively high fluid pressures in the channel 82 revolving around the axis A, leakage fluid overflowing into the gap R and filling it occurs. This leakage fluid has the advantage that it fluidically dampens engine noise and that it contributes to a rapid thermal transfer of heat generated in the engine 18 to the cooling fins 74. However, the aim is to prevent the leakage fluid that has penetrated into the gap R from penetrating into the encapsulated interior of the motor housing 48 via the slide bearing 54. For this purpose, in dynamic operation, ie when there is a relative rotation between the motor housing 18 - and the associated sealing bush 64 - and the second housing part 16, the sealing bush 64 with its return thread formations develops a sealing effect. The thread formations on the sealing bushing 64 are designed such that flow effects occur when rotating in the valleys of the thread formations, which promote the leakage fluid located there to a leakage channel 84 running in the circumferential direction, which is then connected to the environment via a drain hole 86 and a ball valve 88 for draining excess leakage fluid. If the leakage should become too large quantitatively, a return (not shown in detail) to the cooling circuit can be provided.

The pump described with reference to FIGS. 1 to 3 can thus prevent large leakage fluid quantities when fluid is conveyed from the axial opening 66 through the channels 22 of the impeller wheel 20 to the peripheral channel 82 and out of it via the outlet connection 80 penetrate into the gap R and penetrate into the interior of the pot-like motor housing 48. This is particularly advantageous if, on the one hand, undesired contact between the motor components - magnetic ring 50, laminated core 40 and windings 42 - is to be prevented, for example in a case in which the pump also uses aggressive media that could attack or even damage the motor components , should be promoted. Sensitive media, in which contact between motor components and fluid should be avoided to avoid contamination, can also be pumped with such an encapsulated pump.

In addition, the pump arrangement shown in FIG. 1 can also be used to avoid undesirable “splashing losses” which occur, for example, in pumps in which the rotating motor components are located directly in the fluid to be conveyed and rotate against its fluidic resistance.

The pump structure shown in FIG. 1 has the further advantage that the electric motor 18 can be made compact due to its design as an external rotor motor and the overall space occupied by the pump 10 can thus be greatly reduced compared to conventional pumps. This is also due to the fact that the structure shown has a reduced number of parts, in particular because the impeller wheel 20 is also used in combination with the pot-shaped or bottle-shaped motor housing 48 for encapsulation, and also because the ball bearing 32 and the small-sized slide bearing 54 have a small construction Bearing arrangement is used, and also because the cup-shaped motor housing 48 is simultaneously designed as a magnetic yoke (yoke) to provide a magnetic yoke. Further exemplary embodiments of the present invention are described below. It should be pointed out that the same reference numerals are used for components of the same type or having the same effect as in the description of the first exemplary embodiment according to FIGS. 1 to 3, but supplemented with lower case letters to differentiate the individual exemplary embodiments.

FIG. 4 shows a second exemplary embodiment of the pump according to the invention, which is generally designated by reference number 10a. The exemplary embodiment according to FIG. 4 differs from the exemplary embodiment according to FIGS. 1 to 3 in particular in the following points: the impeller wheel 20a is provided in its radially outer region with an edge 90a which is elongated in the axial direction. On the end face of the edge 90a, which is orthogonal to the axis A, the latter abuts with a corresponding end face of the motor housing 48a, which is shortened in the axial direction compared to the first exemplary embodiment. The two end faces are glued or welded together, in any case sealed. The motor housing 48a as well as the impeller wheel 20a are made of a lightweight plastic material or aluminum, which are very sensitive to corrosion, are light and easy to machine and have good thermal conductivity properties. As a result, the combination of motor housing 48a and impeller wheel 20a can no longer serve as a magnetic yoke for the magnetic ring 50a, so that an additional ring element 92a is provided between the components of the motor housing 48a and the edge 90a of the impeller wheel 20a and the magnetic ring 50a provides magnetic inference.

Furthermore, the impeller wheel 20a has a thread formation 94a on its radially outer region, which acts as a dynamic seal in the manner of a return thread seal and limits the penetration of fluid to be pumped into the gap R between the second housing part 16a and the components motor housing 48a or edge 90a , These measures mean that the sealing ring 60 and the external threaded ring 62 can be omitted in comparison to the first embodiment according to FIGS. 1 to 3. Likewise, threaded formations 96a are provided on the area of the motor housing 48a remote from the impeller, which are oriented analogously to the sealing bush 64 according to the first exemplary embodiment according to FIGS. 1 to 3 and together with the leakage channel 84a, the drain hole 86a and the ball valve 88a for removing leakage fluid the gap R. As a further difference to the first exemplary embodiment, according to the second exemplary embodiment Figure 4 replaced the plain bearing bush 54 by a spherical ring seal 98a. The dome ring 98a assumes a bearing function on the one hand, but also a sealing function on the other hand, so that the ingress of leakage fluid to the motor components magnetic ring 50a, bleck packet 40a and windings 42a can be prevented.

FIG. 5 shows a third exemplary embodiment of the pump according to the invention, which is generally designated by reference number 10b. This embodiment results from a combination of the first two exemplary embodiments according to FIGS. 1 to 4 of the present invention. In this case, a thread formation 94b is again provided on the outer circumference of the impeller wheel 20b, which ensures dynamic sealing of the gap R. The motor housing 48b is produced in accordance with the motor housing 48 from FIG. 1 from soft magnetic material and thus ensures a magnetic yoke to the magnetic ring 50b. The motor housing 48b is encompassed by the impeller wheel 20b and accommodated therein. Otherwise, the structure according to the third exemplary embodiment according to FIG. 5 essentially corresponds to the structure of the first exemplary embodiment according to FIG. 1.

Figure 6 shows a fourth embodiment of the pump according to the invention, which is generally designated by the reference numeral 10c. This fourth exemplary embodiment is explained below with regard to its differences from the second exemplary embodiment described above with reference to FIG. 4.

The essential difference between the fourth exemplary embodiment according to FIG. 6 and the second exemplary embodiment according to FIG. 4 is that the ball bearing 32a has been replaced by a slide bearing 100c which is axially secured on the shaft 38c via a ring arrangement 102c and 104c. By using the plain bearing 100c, a ball bearing that is more expensive to buy can be replaced on the one hand, and on the other hand space can be saved in the area of the pump 10c near the impeller wheel. Another difference between the fourth exemplary embodiment according to FIG. 6 and the second exemplary embodiment according to FIG. 4 lies in the fact that a labyrinth seal is formed in the gap R between the pump housing 48c and the second housing part 16c. The labyrinth seal is realized in that ring projections 106c and 108c engage in corresponding ring recesses 110c and 112c. As a result, the gap R has a labyrinthine course, which makes it difficult for leakage fluid to pass through. In addition, the fourth embodiment according to FIG. reaches the end of the motor housing 48c remote from the impeller, a sealing bushing 64c with thread formations which, as a thread return seal, discharge leakage fluid via the drain hole 86c, as has already been described for the first exemplary embodiment according to FIGS. 1-3.

FIG. 7 shows a fifth embodiment of the pump according to the invention, which is generally designated with the reference symbol 10d. The structure of this fifth embodiment in the area near the impeller wheel and in the design of the pump motor 18d is essentially the same as that of the second exemplary embodiment according to FIG. 4. The fifth embodiment has an impeller wheel-free bearing and sealing arrangement which is modified compared to the second embodiment according to FIG. The motor housing 48d is mounted with its shoulder 52d in a slide bearing bush or a sealing bush 114d, this slide bearing bush 114d, in particular a ceramic bushing, being fixed in a rotationally fixed manner via a threaded bolt 116d screwed into the second housing part 16d. Furthermore, a calotte seal 98d can be provided in this area, which is held in the motor housing 48d via a sealing bushing 64d provided with threads. The calotte seal 98d assumes the sealing and bearing function. The sealing bushing 64d is provided with thread formations in order to dynamically convey leakage fluid to the drain hole 86d and via this to the surroundings.

FIG. 8 shows a sixth embodiment of the pump according to the invention, which is generally designated 10E. This sixth embodiment of the invention is designed in its area near the impeller wheel 20e essentially like the first exemplary embodiment according to FIG. 1, only one sealing ring 60e being provided to prevent leakage fluid from penetrating into the gap R between the second housing part 16e and the motor housing 48e to counteract. In the area remote from the impeller, an O-ring 118e is provided on the slide bearing bush 54e, which is intended to prevent leakage fluid from penetrating to the bearing bush 54e. The essential special feature of the sixth embodiment shown in FIG. 8 compared to the previously described embodiments is that it is provided with a sensor system for detecting the engine rotation. This sensor system comprises magnetic elements 120e attached to the motor housing 48e, which rotate with the motor housing 48e in accordance with a motor rotation. Corresponding to the magnetic elements 120e, sensors 122e are provided on the second housing part 16e of the pump housing 12e. hen. A relative rotation between the motor housing 48e and the pump housing 12e can be detected by means of the magnetic elements 120e and the sensors 122e. In other words, the current state of rotation of the pump, ie the speed, can be determined via the sensors, including the magnetic elements 120e and the sensors 122e, so that the pump 10e can easily be integrated into a control system. The signals detected by the sensor system are passed via leads 124e to evaluation electronics, not shown.

FIGS. 9 and 10 show a seventh exemplary embodiment of the present invention, which is essentially based on the first exemplary embodiment according to FIGS. 1 to 3 with regard to the design of the motor, the precautions for sealing and with regard to storage. The difference, however, lies in the fact that the fluid flowing axially through the opening 66f also leaves the pump again in the axial direction via an outflow connection 126f, in contrast to the exemplary embodiments described above, in which the fluid essentially flowed out in the radial direction - in FIG. 1 Via the outlet connection 80. The axial discharge of the fluid is achieved in that, as shown in FIG. 10, a plurality of semicylindrical channels 128f are formed radially around the second housing part 16f, which are radially formed by a now also cup-shaped first housing part 14f are sealed on the outside. A closure hood 13 Of is then provided on the right-hand side in FIG. 9.

The exemplary embodiments described above show various possibilities of how simple, compact pumps of small construction can be obtained with an encapsulated electric motor with high motor efficiency, which pumps can be used independently of the sensitivity and properties of the fluid to be pumped.

The features disclosed in the above description, the figures and the claims can be important both individually and in any combination for the implementation of the invention in the various configurations.

Claims

5 claims

1. Electric motor (18) for use as a pump motor with: a stator (40) provided with at least one winding (42), an outer rotor (50) encompassing the stator (40) and

IÖ - a hub which is connected to the outer rotor (50) in a rotationally fixed manner and is provided with a pump wheel (20), the outer rotor (50) and the hub being rotatable via a bearing arrangement (32, 54) on a shaft holding the stator (40) (38) or shaft are mounted, the bearing arrangement (32, 54) a first bearing (32) close to the pump wheel and a second bearing remote from the pump wheel

15 (54), and the electric motor (18) is assigned a motor housing (48) which forms a first hub part and which is designed such that it together with the pump wheel (20) the stator (40) and the outer rotor (50 ) encapsulates sealed, the pump wheel (20) forming a second hub part.

20 2. Electric motor (18a) according to Anspmch 1, characterized in that the motor housing (48a) is flanged to the pump impeller (20a).

3. Electric motor (18) according to Anspmch 1, characterized in that the motor housing (48) is sealingly received in the pump wheel (20).

25

4. Electric motor (18) according to one of claims 1 to 3, characterized in that the motor housing (48) is made of a soft magnetic material.

5. Electric motor (18a) according to one of claims 1 to 3, characterized in that the motor housing (48a) is made of a non-magnetic material and that between the outer rotor (50a) and the hub (30a, 48a) is a soft magnetic yoke (92a) is provided.

6. Electric motor (18c) according to one of claims 1 to 5, characterized in that the first bearing (100c) is designed as a slide bearing which is axially secured on the shaft (38c).

7. Electric motor (18) according to one of claims 1 to 5, characterized in that the first bearing (32) is designed as a roller bearing, in particular as a ball bearing (32).

8. Electric motor (18) according to one of claims 1 to 7, characterized in that the first bearing (32) is received in a bearing receptacle formed in the pump wheel (20).

9. Electric motor (18) according to one of claims 1 to 8, characterized in that the bearing arrangement, in particular in the region of the first bearing (32), is axially clamped.

10. Electric motor (18) according to Anspmch 10, characterized in that for the axial bracing of the bearing arrangement between the shaft (38) and the pump wheel (20) a spring element (36) pretensioned in the axial direction (A), in particular an elastomer spring element (36), and a ball (56) engaging on the spring element (36) is arranged.

11. Electric motor (18) according to one of claims 1 to 10, characterized in that the second bearing (54) is designed as a plain bearing, in particular as a compact sintered bearing, plastic bearing, ceramic bearing or spherical bearing.

12. Electric motor (18) according to one of claims 1 to 11, characterized in that the second bearing (54) is accommodated in a bearing receptacle (52) formed in the motor housing (48).

13. Electric motor (18c) according to one of claims 1 to 12, characterized in that between the shaft (38e) and the motor housing (48e) in the region of the second Bearing (54e) at least one radial seal (64e), in particular at least one mechanical seal or at least one O-ring (118e), is provided.

14. Electric motor (18a) according to one of claims 1 to 13, characterized in that between the shaft (38a) and the motor housing (48a) in the region of the second

Bearing at least one resilient axial seal (98a) is provided.

15. Electric motor (18) according to one of claims 1 to 14, characterized in that between the shaft (38) and the motor housing (48) in the region of the second bearing

10 (54) at least one return thread seal (64) is provided, the

Return thread is formed either on the shaft or on the motor housing (48) or on a sealing bush (64) between the shaft (38) and the motor housing (48).

16. Electric motor (18) according to any one of claims 1 to 15, characterized ι, ₅ that the shank (38) having a bore (46) for receiving leads (44) to the

Stator (40) is provided.

17. Pump (10) for conveying fluids, carried out with an electric motor (18) according to one of claims 1 to 17, wherein the pump (10) receiving the electric motor (18)

20 pump housing (12) with an inlet (66) and an outlet (80) for feeding and

Has drainage of the fluid.

18. Pump (10) according to Anspmch 17, characterized in that a thin gap (R) is provided between the pump housing (12) and the hub (20, 48). 5

19. Pump (10) according to Anspmch 18, characterized in that in a region near the pump wheel on the pump housing (12) and / or on the hub (20, 48) for sealing the gap (R), a gap seal (60, 62), in particular a sealing ring (60) and / or a return thread seal (62) is provided.

30

20. Pump (10) according to Anspmch 18 or 19, characterized in that a further gap seal (64) for sealing the gap (R) is provided in a region of the hub (20, 48) remote from the pump wheel near the second bearing (54).

21. Pump (10) according to one of claims 18 to 20, characterized in that the further gap seal (64) is a labyrinth seal (106c, 108c, 110c, 112c) and / or an annular seal, in particular an O-ring, and / or a thread return seal (64).

22. Pump (10) according to Anspmch 21, characterized in that the return thread seal (64) is formed with a thread pitch oriented in the axial and / or in the radial direction.

23. Pump (10) according to one of claims 18 to 22, characterized in that the gap (R) is connected to an overflow (84, 86, 88) for removing or returning excess fluid.

24. Pump (10) according to any one of claims 17 to 23, characterized in that it is designed as an axial pump, in which the fluid to be delivered is discharged in the axial direction.