WO2013060311A1

WO2013060311A1 - Partial flow guide, in particular of a magnetic drive pump

Info

Publication number: WO2013060311A1
Application number: PCT/DE2012/000940
Authority: WO
Inventors: Günther Schneider; Michael Westib
Original assignee: Ruhrpumpen Gmbh
Priority date: 2011-10-28
Filing date: 2012-09-24
Publication date: 2013-05-02
Also published as: DE102011117182A1

Abstract

The invention relates to a magnetic drive pump comprising a shaft having a through-hole and an impeller-sided sliding bearing and a sliding bearing which is at a distance from the impeller, an inner magnetic rotor (4) being arranged on the shaft, said inner magnetic rotor resting at least on a bearing housing (6) at least in parts, and a fluid gap (8) is formed. Said magnetic drive pump (1) is characterised in that the fluid gap (8) comprises a flow varying element (19).

Description

Partial flow guide, in particular a magnetic coupling pump

The invention relates to a magnetic coupling pump, which has a shaft with a through hole and an impeller-side sliding bearing and a rotor-bearing plain bearing, wherein on the shaft, an inner magnet rotor is arranged, which abuts at least partially on a bearing housing, wherein a medium gap is formed.

[0002] Such magnetic coupling pumps are generally known, and are described, for example, in DE 10 2009 022 916 A1. In this case, the pump power from a drive shaft via a magnet-bearing rotor (outer rotor) without contact and substantially slipless on the pump-side magnet carrier (inner rotor, first drive element) is transmitted. The inner rotor or the first drive element drives the pump shaft, which is mounted in a sliding bearing lubricated by the conveying medium, ie in a hydrodynamic slide bearing. Between the outer rotor and the inner rotor, so between the outer and the inner magnet is a containment shell with its cylindrical wall. The containment shell is connected at its flange to a pump component, for example a housing cover, and has a closed bottom opposite thereto. The containment shell, so the magnetic coupling pump reliably separates the product space from the environment, so that the risk of product leakage can be excluded with all the associated negative consequences. A magnetic coupling pump is therefore the combination of a conventional pump hydraulics with a magnetic drive system. This system uses the attraction and repulsion forces between magnets in both coupling halves for non-contact and slip-free torque transmission. Especially when dealing with very valuable or very dangerous substances, the magnetic coupling pump therefore has great advantages. EP 0 814 275 B1 deals with a hydrodynamic sliding bearing of a magnetic coupling pump, which is designed as a combined axial and radial bearing. The slide bearing of EP 0 814 275 B1 has two bearing sleeves, two bearing bushes which can be slid on the bearing sleeves, a spacer sleeve arranged between the bearing sleeves and a spacer bush arranged between the bearing bushes. The bearing sleeves and bushings are formed of a ceramic material, wherein the spacer sleeve or bushing is formed of a metal. To create a hydrodynamic sliding bearing, which can be produced inexpensively

CONFIRMATION COPY should be and should be designed so that at any time sufficient lubrication passes through the medium to be conveyed in the plain bearing, proposes EP 0 814 275 B1, that the inner diameter of the bearing sleeves is greater than the inner diameter of the spacer sleeve. Furthermore, EP 0 814 275 B1 proposes that a partial flow of the conveying medium passes the impeller-free sliding bearing passing through a passage of the inner magnet rotor into the containment shell, from where the delivery medium passes into the passage bore of the shaft, and returned to the suction region of the pump becomes. A disadvantage of this configuration may be that the desired positive guidance of the conveying medium partial flow is not given by the inner magnet rotor in the pressure chamber and from there into the hollow-drilled shaft, for example, if the corresponding pressure conditions are unfavorable. In such a case, the conveyed medium heated by the magnetic power loss could be pressed against the actually provided (forced) flow direction by the inner magnet rotor, or through the channel passage bore thereof against the axial bearing element remote from the rotor, so that the respective axial thrust loaded axial bearing element is already heated Partial conveying medium flow is lubricated, which can lead to a bearing damage in the worst case.

The invention has for its object to improve a magnetic coupling pump of the type mentioned by simple means or to create, in which always a secure cooling and lubrication is ensured with fluid.

According to the invention the object is achieved by a magnetic coupling pump with the features of claim 1, wherein the medium gap has a Strömungsver- changing element.

[0006] It should be noted that the features listed individually in the claims can be combined with one another in any technically meaningful manner and show further embodiments of the invention. The description additionally characterizes and specifies the invention in particular in connection with the single FIGURE.

The magnetic coupling pump has the inner magnet rotor and the bearing housing. Both lie with corresponding surfaces to each other, of course, a medium gap between the two surfaces (Trägeranlaufzone) is provided. Through the medium gap, a medium partial flow in the direction of Channel passage bore flow, wherein a leakage flow can flow through the medium gap. In this respect, the medium gap has only the function of a leakage gap, with neither cooling nor lubrication is absolutely necessary. The respective plain bearing has radial bearing elements, that is to say a bearing bush and a bearing sleeve and the axial bearing element or a bearing disk. Between opposing sliding surfaces of the bearing bush and the bearing sleeve, a lubrication groove is provided which is introduced into the sliding surface of the bearing bush. The respective lubrication groove can be embodied with a rounded profile, which has a curvature oriented away from this, with respect to a center axis of the bearing bush, that is to say it is preferably convex. The pumped medium, which is taken in a known manner to supply the sliding bearings but also for heat dissipation of the magnetic power loss, passes both through the impeller away lubrication past the bearing disk over and through the medium gap to the channel through-hole where both streams unify nigen and in the containment shell or be led into the pressure chamber.

Furthermore, the magnetic coupling pump on a second drive element, which may also be referred to as an external magnet rotor. Between two magnet rotors the containment shell is arranged. The cooling medium flow, which flows into a cooling gap within the containment shell and ends in the bottom region of the containment shell, ie in a pressure space, is used to dissipate the heat loss.

The cooling medium flow is of course heated after passing through the cooling gap, with the invention advantageously a flow of heated medium from the pressure chamber is avoided to the impeller bearing plain bearing. From the pressure chamber, the cooling medium flow passes into the through hole of the shaft and is conveyed to the suction side of the conveying element or the magnetic coupling pump. The flow through the hollow-bored shaft is well known in the art.

In order to increase the pressure in the entire sliding bearing area, can be provided purposeful that the impeller near the impeller in its course towards the outlet side to the impeller bearing disc is conical, with the impeller near the impeller preferably tapers to the outlet side. In this case, a corresponding adaptation, ie a corresponding conical configuration, can only be sufficient for the surface of the bearing bush close to the running wheel. As the feed amount increases, the back pressure increases at the (inner) end face of the inner magnet rotor, which leads to a reduction of the axial thrust to the suction side, wherein the (impeller) axial bearing element, or the (impeller) bearing disc is relieved.

It is also beneficial that flows through the cooling gap percentage of more fluid than through the medium gap. In order to achieve that the partial flow through the medium gap is further reduced, at the same time the cooling medium flow through the cooling gap is further increased, which immediately causes a pressure reduction at the outlet of the medium gap to the bearing disc, so that the lubricating medium flow for lubrication of the (impeller) slide bearing on the Bearing disk is forcibly guided in the low pressure range, is provided purposefully in the invention that the medium gap, the flow change element, preferably in the embodiment as a throttle element.

With the flow-changing element or with the throttle element of the partial flow amount is reduced in the medium gap or in the Trägeranlaufzone. The flow change element can be embodied as a labyrinth, it being expedient to provide the grooves of the labyrinth in the corresponding surface of the bearing housing, that is to say in a non-rotating component. With these measures, the frontal pressure, which acts on the inner end face of the inner magnet rotor, increases in parallel, which ensures that the amount of partial flow through the cooling gap or the cooling medium flow, as already mentioned, is increased, whereby e.g. In the case of low-boiling media to be conveyed, the heat input into the medium is reduced by the larger tangential flow through the cooling gap. Furthermore, with the advantageous measure, the axial thrust of the pump can be better controlled, since the prevailing pressure on the end face of the inner magnet rotor near the impeller is increased in magnitude, whereby the impeller-remote thrust bearing element or the bearing disk remote from the impeller is relieved.

Further advantageous embodiments of the invention are disclosed in the subclaims and the following description of the figures. It shows the only Fig. 1 shows a detail of a magnetic coupling pump in one

Sectional view. Figure 1 shows a section of a magnetic coupling pump 1 with a pump shaft, for example as a stainless steel shaft, which carries an impeller, and which is mounted in a hydrodynamic sliding bearing, wherein the hydrodynamic sliding bearing externally lubricated by fluid, but also with another, product-compatible fluid can be. The exemplary magnetic coupling pump 1 is known with its individual components per se, for example from EP 0 814 275 B1, which is why it is not described in detail.

The magnetic coupling pump 1 has a roller bearing near plain bearing and a drive bearing plain bearing. The respective plain bearing has a bearing sleeve, a bearing bush 2 and a thrust bearing element 3 or a bearing disk 3.

Between the respective bearing bush 2 and the respective bearing sleeve, a lubrication groove is arranged, which is introduced into the bearing bush 2. The respective lubrication groove can be embodied with a rounded course, which has a curvature oriented away from this, with respect to a center axis of the bearing bush 2, ie is preferably convex.

The inner magnet rotor 4 engages over the bearing housing 6 in regions, so that a so-called carrier start-up zone 7 is formed, in which a medium gap 8 is arranged. The medium gap 8 is thus arranged between mutually opposite surfaces of the bearing housing 6 and the inner magnet rotor 4. The inner magnet rotor 4 is in operative connection with a driven outer magnet rotor 9. Between two magnet rotors 4 and 9, a split pot 1 1 is arranged, which opposite to the impeller has a bottom 12, so that a pressure chamber 13 is formed. Between the containment shell 1 1 and the inner magnet rotor 4, a cooling gap 14 is arranged, which opens into the pressure chamber 13.

In the shaft, a through hole is introduced, which is open to the pressure chamber 13 out. Opposite, the through hole has a medium connection or a channel system to the impeller of the exemplary magnetic coupling pump 1. The invention aims at the advantageous partial flow guide for cooling and lubrication of the magnetic coupling pump 1, for example, with pumped medium.

The fluid is removed at a point of high pressure in the impeller and passed through a bore through the housing cover in a collection bag. The collection bag is formed on the one hand by a section of the can 11, a portion of the bearing housing 6 and the impeller near the end face of the inner magnet rotor 4. The guided into the collection bag medium flow flows with a partial flow 16 through the cooling gap 14 into the pressure chamber 13, and is passed with a second partial flow 17 through the medium gap 8.

The lubricating medium flow, which is removed at another location and is passed into a lubricating pocket between the plain bearings, is divided into two lubrication streams. The first lubrication flow 20 flows through the off-wheels lubrication around the impeller remote thrust bearing element in a channel formation, which is designed as a channel passage bore 18, and through this into the pressure chamber 13. The partial flow 17 via the medium gap 8 also passes into the channel passage bore 18th

To increase the pressure in the entire sliding bearing area is provided in one embodiment of the invention that the impeller near the wheel lubrication is made conical. Preferably, it is provided that the impeller near the impeller narrowing tapered from its lubrication pocket oriented input side to the opposite outlet side in its inside diameter, wherein only the bearing bush is machined on its surface, that results in the conical shape of the wheel near lubrication. The medium pressure at the outlet of the wheel-far lubrication is directly dependent on the feed amount of the medium in the collection bag. With increasing feed amount into the collection pocket, the back pressure increases at the impeller near end face of the inner magnet rotor 4, resulting in a reduction of the axial thrust to the suction side, whereby the impeller-distant bearing disc 3 is relieved. By way of example, the end-side pressure on the impeller-near end face of the inner magnet rotor 4 has a smaller amount than the delivery of the magnetic coupling pump 1. From the cooling medium flow, a higher percentage flows through the cooling gap 14 into the pressure chamber 13 than through the medium gap 8 to the channel passage bore 18th

To reduce the partial flow amount, which flows through the medium gap 8, this advantageously has a flow modification element 19, preferably a throttle element 19 in the exemplary embodiment as a labyrinth 19, so that the amount of partial flow which flows through the medium gap 8 by way of example 10 - 30%, for example, reduced by 20%, at the same time the amount of the cooling medium flow through the cooling gap 14 by example 10 - 30%, for example, increased by 20%. As a result, the end-side pressure on the impeller-near end side of the inner magnet rotor 4 is simultaneously increased, whereby the pressure at the outlet of the medium gap 8 is reduced, so that the first lubrication flow for the lubrication of the impeller-free slide bearing is forced into a low pressure range. With increasing the front-side pressure acting on the end near the impeller, the cooling medium flow is increased in magnitude, so that, for example, the heat input into the cooling medium flow is reduced by the larger tangential flow in the case of low-boiling media, wherein, moreover, the axial thrust of the magnetic drive pump can be better controlled , as the off-wheels bearing disc is relieved. The throttle element 19 could also be designed as a delivery thread. The target is when the throttle element 19 is arranged in the non-rotating component or in the bearing housing. The throttle element 19 embodied as a labyrinth 19 has grooves 21 which are spaced apart from one another in the axial direction and which are arranged or introduced into the relevant surface of the bearing housing 6. Only by way of example four successive grooves 21 are provided, wherein the partial flow 17, so the leakage flow in the medium gap 8 is swirled, which affects a reduction of the flow rate. This is indicated in FIG. 1 by means of the (smaller) arrows above the grooves 21. The throttle element 19 causes an increase in pressure at the inlet of the medium gap 8, whereby the frontal pressure on the impeller-near end face of the inner magnet rotor 4 is increased. Of course, more or less grooves can be provided.

With the invention, a partial flow guide is achieved in magnetic coupling pumps, with which a cooling and lubrication is always ensured. LIST OF REFERENCE NUMBERS

1 magnetic drive pump

2 bearing bush

3 thrust bearing element

4 inner magnet rotor

5

6 bearing housing

7 carrier start-up zone

8 medium gap

9 Outer magnet rotor

10

11 containment shell

12 floor

13 pressure chamber

14 cooling gap

15

16 partial flow through 14

17 partial flow through 8

18 channel passage hole

19 flow change element / throttle element

20 First lubrication flow

21 grooves

Claims

claims

1. A magnetic coupling pump which has a shaft with a through hole and an impeller-side sliding bearing and a non-impeller sliding bearing, wherein on the shaft, an inner magnet rotor (4) is arranged, which abuts at least partially on a bearing housing (6), wherein a medium gap (8) formed is, characterized in that the medium gap (8) has a flow change element (19).

2. Magnetic coupling pump according to claim 1, characterized in that the flow change element (19) in a non-rotating component, preferably in the bearing housing (6) is arranged.

3. Magnetic coupling pump according to claim 1 or 2, characterized in that the flow change element (19) is designed as a throttle element (19).

4. Magnetic coupling pump according to one of the preceding claims, characterized in that the flow change element (19) is designed as a labyrinth (18).

5. Magnetic coupling pump according to one of the preceding claims, characterized in that the flow change element (19) is designed as a delivery thread.