EP2994641B1 - Magnetic drive pump assembly - Google Patents

Description

The invention relates to a magnetic coupling pump assembly having a housing formed by a pump housing of the pump assembly, a containment shell hermetically seals a chamber enclosed by it against the interior formed by the pump housing, an impeller shaft rotatably driven about a rotation axis, an impeller arranged at one end of the impeller shaft an inner rotor arranged at the other end of the impeller shaft, a drive motor, a drive shaft rotatably driven by the drive motor and an outer rotor cooperating with the inner rotor and disposed on the drive shaft, the outer rotor having a hub and a first support member, the outer rotor between the hub and the first support member has a hollow cylindrical portion and the axial fixing of the outer rotor to the drive shaft is effected by a fastener.

Such a pump arrangement is known from WO 2005/017362 A1 known.

Such pump assemblies are widely used and find application in almost all areas of industry. Machines of the present type are also used in potentially explosive areas. For the various production and conveying systems, especially in the field of chemistry, there are special regulations in connection with explosion protection. In such systems find on the one hand work machines, such as pumps or turbines, as non-electrical equipment, and on the other hand, power machines, such as drive motors, as electrical equipment, Use. For electrical devices have long been proven safety standards. These standards specify which structural measures have to be taken in order to be able to use an electrical device in the various potentially explosive atmospheres. In such rooms, in which the development of an explosive atmosphere is possible, the sources of ignition, that is, the formation of friction and impact sparks, frictional heat and electrical charge must be avoided and possible effects of an explosion by preventive and constructive measures are taken into account. Explosion-proof block motors, in particular standard motors in flange design, allow only a certain heat input into the motor at the interfaces, in particular flange and shaft, such that the maximum permissible temperatures of the motor are not exceeded.

Meanwhile, it is known that in magnetic coupling pump assemblies of the main heat input into the drive motor is effected by the drive shaft, since the outer magnetic carrier of the magnetic coupling is exposed to both the media temperature, as well as the increase in temperature by the eddy current losses. Due to the poor heat dissipation of the outer magnetic carrier due to the likewise heated pump housing, the heat energy is entered to a large extent directly into the drive shaft.

In the DE 298 14 113 U1 This problem is circumvented by the outer rotor, referred to as the driver, and the drive motor being in drive connection via a drive means made of poorly heat-conducting material. The disadvantage here is the cost-intensive embodiment with an intermediate outer rotor. Because in addition to the necessary components in addition to the motor bearings and the outer rotor stored deep groove ball bearings are to be maintained. In addition, the thermal lock function is only existent on the interface to the motor shaft stub. However, since the heat is entered directly into the inner ring of deep groove ball bearings, there is a widening of the inner ring and thus to the stress of the bearing and thus to reduce the service life. In an embodiment acting with coolant, the outer rotor runs in the coolant, resulting in considerable friction losses, which significantly reduce the efficiency of the pump.

The object of the invention is to provide a pump assembly which allows for increased temperature of the medium to be delivered, while maintaining the explosion protection of the drive motor, a reduction of the axial and radial space and ease of assembly.

The object of the invention is achieved in that the fastening element has a first external thread at one end and a second external thread at the end opposite the first external thread, wherein between the first external thread and the second external thread is a spacer holding portion whose outer diameter is larger than that Outer diameter of the first external thread and the second external thread.

Characterized in that the hub is not disposed directly on the first support member, but the hollow cylinder-like portion is connected downstream of the drive shaft, the heat input is reduced by the outer magnet carrier in the drive shaft and thus in the drive motor.

According to one embodiment of the invention, the hollow-cylindrical portion and the hub with respect to the first support member are formed thin-walled. The hollow cylindrical portion and the hub each have a wall with a certain wall thickness, wherein the wall thickness of the wall of the hollow cylindrical portion and the wall thickness of the wall of the hub is smaller than the radius of the drive shaft and chosen so that in each case a safe torsion - And bending fatigue strength is guaranteed. This leads to a further reduction of the heat input from the outer magnet carrier in the drive shaft of the drive motor. The axial fixing of the outer magnetic carrier to the drive shaft is effected by a fastening element. In this case, according to the invention, the fastening element has at one end a first external thread and at the end opposite the first external thread second external thread, wherein between the first external thread and the second external thread is a Distanzhalteabschnitt whose outer diameter is greater than the outer diameter of the first external thread and the second external thread.

To be particularly advantageous, an embodiment has been found, according to which the distance holding portion has on the side close to the first external thread side a collar with enlarged outer diameter, whereby the fastening element can be positioned exactly axially and uncomplicated.

Alternatively, the spacer portion on the side close to the first external thread may taper conically.

Appropriately, a radial threaded bore is formed in the hub into which a screw is screwed. Thus, during standstill of the pump assembly, the hub is moved into abutment with the location of the drive shaft where the hub engages during operation. As a result, a high concentricity is achieved.

Fig. 1

den Längsschnitt durch eine Magnetkupplungspumpenanordnung mit einem erfindungsgemäßen Außenrotor, die

Fig. 2

einen der Fig. 1 entsprechenden Außenrotor in vergrößerter Darstellung und die

Fig. 3

einen Schnitt entlang der Linie III-III aus Fig. 2.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below. It shows the

Fig. 1

the longitudinal section through a magnetic coupling pump assembly with an external rotor according to the invention, the

Fig. 2

one of the Fig. 1 corresponding outer rotor in an enlarged view and the

Fig. 3

a section along the line III-III Fig. 2 ,

The Fig. 1 shows a pump assembly 1 in the form of a magnetic coupling pump assembly with a pump part and an electrical part. The pump part of the pump arrangement 1 has a multipart pump housing 2 of a centrifugal pump, which comprises a hydraulic housing 3 designed as a spiral housing, a housing cover 4, a bearing support lantern 5 and a connecting element 6.

The hydraulic housing 3 has an inlet opening 7 for sucking in a conveyed medium and an outlet opening 8 for ejecting the conveyed medium. The housing cover 4 is arranged at the inlet opening 7 opposite side of the hydraulic housing 3. On the side facing away from the hydraulic housing 3 of the housing cover 4, the bearing support lantern 5 is attached. The connecting element 6 is attached to the housing cover 4 opposite side of the bearing bracket lantern 5. To the connecting element 6, a drive motor 9 forming the electrical part is arranged on the opposite side of the bearing support lantern 5.

A containment shell 10 is fastened to the side of the housing cover 4 facing away from the hydraulic housing 3 and extends at least partially through an inner space 11 bounded by the pump housing 2, in particular by the housing cover 4, by the bearing support lantern 5 and by the connecting element 6. The containment shell 10 seals one of enclosed chamber 12 hermetically against the interior 11 from.

A rotatable about an axis of rotation A impeller shaft 13 extends from a limited by means of the hydraulic housing 3 and the housing cover 4 flow chamber 14 through an opening provided in the housing cover 4 opening 15 in the chamber 12th

An impeller 16 is fastened to a shaft end of the impeller shaft 13 located within the flow chamber 14, an inner rotor 17 arranged inside the chamber 12 is arranged at the opposite end of the shaft, which has two shaft sections 13a, 13b with increasing diameters. The inner rotor 17 is equipped with a plurality of magnets 18, which are arranged on the side of the inner rotor 17 facing the gap pot 10.

Between the impeller 16 and the inner rotor 17, a bearing assembly 19 operatively connected to the impeller shaft 13 rotatably driven about the rotation axis A is arranged.

The drive motor 9 comprises a drive shaft 20. The drive shaft 20 which can be driven about the axis of rotation A is arranged essentially coaxially to the rotor shaft 13. The drive shaft 20 extends into the connecting element 6 and possibly at least partially into the bearing support lantern 5. At the free end of the drive shaft 20, a plurality of magnets 21 supporting outer rotor 22 is arranged. The magnets 21 are arranged on the side of the outer rotor 22 facing the containment shell 10. The outer rotor 22 extends at least partially over the containment shell 10 and interacts with the inner rotor 17 together, such that the rotating outer rotor 22 by means of magnetic forces the inner rotor 17 and thus the impeller shaft 13 and the impeller 16 is also placed in a rotational movement.

The Indian Fig. 2 outer rotor 22 shown enlarged comprises a hub 23 with an outer circumferential surface 24, a hollow cylinder-like portion 25 formed on the side facing away from the drive motor 9 hollow cylindrical portion 25 with a cell 27 bounded by a wall 26. The outer rotor 22 further comprises a facing on the gap pot 10 Side of the hollow cylinder-like portion 25 formed or arranged flange-like first support member 28 and formed on the first support member 28 or arranged hollow cylinder-like second support member 29 which at least partially surrounds the can 10 and on which the magnets 21 are arranged. First and second support members 28, 29 are shown as two interconnectable parts, but may also be made as one part.

The hollow-cylindrical section 25 has a wall 25a with a wall thickness S1 and the hub 23 has a wall 23a with a wall thickness S2. The hollow cylindrical portion 25 and the hub 23 are formed thin-walled with respect to the first support member 28. The wall thicknesses S1, S2 are substantially smaller than the thickness d1 of the first carrier element 28. The wall thickness S1 of the wall 25a of the hollow cylinder-like portion 25 and the wall thickness S2 of the wall 23a of the hub 23 are selected so that in each case a secure torsional and bending fatigue is ensured. The wall thicknesses S1, S2 are also smaller than the radius r of the drive shaft 20. Preferably, the wall thickness S1 of the wall 25a is smaller than the wall thickness S2 of the wall 23a.

Through the hub 23, a through hole 30 extends into the cell 27 of the arranged between the hub 23 and the first support member 28 hollow cylindrical portion 25 and forms a hub inner surface 31. In the hub inner surface 31 is a parallel to the axis of rotation A extending axial groove 32 is provided. In the drive shaft 20, a keyway 33 oriented toward the axial groove 32 is formed, into which the motor torque is transmitted to the hub 23 of the outer rotor 22 a feather key 34 is inserted. The axial fixing of the outer rotor 22 to the drive shaft 20 is effected by a fastening element 35.

The fastening element 35 has at one end a first external thread 37 which can be screwed into a threaded bore 36 formed coaxially with the axis of rotation A on the end face of the drive shaft 20, and a second external thread 38 at the end opposite the first external thread 37. Between the first external thread 37 and the second external thread 38, a spacer holding portion 39 is formed, whose outer diameter is greater than the outer diameter of the first external thread 37 and the second external thread 38th

The fastening element 35 is screwed into the threaded bore 36 with the first external thread 37 until the spacer holding section 39 comes into contact with the end face of the drive shaft 20. In the in the Fig. 1 and 2 In the embodiment shown, the spacer holding section 39 has, on the side close to the first external thread 37, a collar 40 with an enlarged outside diameter, which bears against the drive shaft 20. The collar 40 is preferably listed as a hexagon or has at least two key surfaces. Alternatively, the spacer holding section 39 on the side close to the first external thread 37 may taper conically and come into abutment with the conical inlet region of the threaded bore 36.

The second external thread 38 extends through an opening 41 in the wall 26, wherein the spacer holding portion 39 of the fastening element 35 is in contact with the wall 26. With a screwed onto the second external thread 38 nut 42, the axial fixing of the outer rotor 22 takes place on the drive shaft 20. The outer rotor 22 is in this way axially accurately positioned and fastened in a simple manner. In addition, a through hole 43 extends from one end face of the fastener 35 to the other to keep the heat transferring the heat from the outer rotor 22 into the drive shaft 20 as small as possible. Alternatively, instead of the through hole 43, a blind hole can be provided, which extends either from the first external thread 37 near end face extends close to or in the spacer portion 39 or from the second external thread 38 near end to the collar 40 or beyond.

The Fig. 3 shows that in the hub 23, a radial threaded bore 44 is formed, in which a screw 45, in particular grub screw, is screwed. The drive shaft 20 facing the end of the screw 45 is preferably formed frustoconical. The threaded bore 44 is always in the direction of rotation of the driven drive shaft 20, which is indicated here by the arrow M, at an angle α of about 35 ° to about 55 ° and preferably at an angle α of 40 ° to 50 ° and preferably at an angle α of about 45 ° to the axial groove 32 is arranged. If necessary, there are further, not shown, threaded holes 44 in the hub 23 along its axial extent. <U> REFERENCE LIST </ u> 1 pump assembly 25a wall 2 pump housing 26 wall 3 hydraulic housing 27 cell 4 housing cover 28 first carrier element 5 Bearing bracket lantern 29 second carrier element 6 connecting element 30 Through Hole 7 inlet port 31 Hub inner surface 8th outlet 32 axial groove 9 drive motor 33 keyway 10 containment shell 34 Adjusting spring 11 inner space 35 fastener 12 chamber 36 threaded hole 13 impeller shaft 37 first external thread 13a shaft section 38 second external thread 13b shaft section 39 Distance holding section 14 flow chamber 40 Federation 15 opening 41 opening 16 Wheel 42 nut 17 inner rotor 43 Through Hole 18 magnet 44 threaded hole 19 bearing arrangement 45 screw 20 drive shaft 21 magnet A axis of rotation 22 outer rotor S1 Wall thickness hollow cyl. section 23 hub S2 Wall thickness hub 23a wall r Radius drive shaft 24 Outer casing surface 25 hollow cylindrical section

Claims (5)

1. Magnetically coupled pump arrangement (1), having an interior space (11) which is formed by a pump housing (2) of the magnetically coupled pump arrangement (1), a split can (10) which hermetically seals a chamber (12), which is enclosed by it, with respect to the interior space (11) which is formed by the pump housing (2), an impeller shaft (13) which can be driven rotatably about a rotational axis (A), an impeller (16) which is arranged at one end of the impeller shaft (13), an internal rotor (17) which is arranged at the other end of the impeller shaft (13), a drive motor (9), a drive shaft (20) which can be driven rotatably about the rotational axis (A) by the drive motor (9), and an external rotor (22) which interacts with the internal rotor (17) and is arranged on the drive shaft (20), the external rotor (22) having a hub (23) and a first carrier element (28), the external rotor (22) having a hollow-cylindrical section (25) between the hub (23) and the first carrier element (28), and the axial fixing of the external rotor (22) on the drive shaft (20) taking place by way of a fastening element (35), characterized in that the fastening element (35) has a first external thread (37) at one end and a second external thread (38) at the end which lies opposite the first external thread (37), a spacer section (39) being situated between the first external thread (37) and the second external thread (38), the external diameter of which spacer section (39) is greater than the external diameters of the first external thread (37) and the second external thread (38).
2. Magnetically coupled pump arrangement according to Claim 1, characterized in that the hollow-cylindrical section (25) and the hub (23) are of thin-walled configuration in comparison with the first carrier element (28).
3. Magnetically coupled pump arrangement according to Claim 1 or 2, characterized in that the spacer section (39) has a collar (40) with an enlarged external diameter on the side which is close to the first external thread (37).
4. Magnetically coupled pump arrangement according to Claims 1 to 3, characterized in that the spacer section (39) tapers conically on the side which is close to the first external thread (37).
5. Magnetically coupled pump arrangement according to one of Claims 1 to 4, characterized in that a radial threaded bore (44) is configured in the hub (23), into which threaded bore (44) a screw element (45) is screwed.

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