CN211314647U - Centrifugal pump and centrifugal pump assembly - Google Patents

Abstract

The utility model relates to a centrifugal pump (50) and centrifugal pump assembly. The centrifugal pump (50) has a pump housing (1, 1a, 1b) and at least one impeller (2) arranged in the pump housing (1, 1a, 1b) for conveying a liquid, the impeller (2) having an intake pipe connection (10a), the intake pipe connection (10a) being sealed radially to the pump housing (1, 1a, 1b) by a wear ring (14), characterized in that the wear ring (14) is slotted and the pump housing (1, 1a, 1b) has an adjustment unit, by means of which the diameter of the wear ring (14) can be adjusted.

Description

Centrifugal pump and centrifugal pump assembly

Technical Field

The present invention relates to the technical field of centrifugal pumps, in particular to so-called Split pumps (Split-Case-pump) having a housing divided into two parts. In particular, the invention relates to a centrifugal pump having a pump housing and at least one impeller arranged in the pump housing for conveying liquid from a suction side to a pressure side of the pump unit, wherein the impeller has an inlet pipe connection which is radially sealed with respect to the pump housing by means of a wear ring. The utility model discloses still relate to one kind and have the centrifugal pump equipment according to the utility model discloses a centrifugal pump.

Background

In the case of centrifugal pumps, the impeller divides the interior of the pump housing into a suction side and a pressure side, wherein the impeller sucks in the liquid to be pumped through a suction nozzle on the suction side, which is annularly surrounded by an intake connection, accelerates tangentially and acts to some extent towards the pressure side. Thus, this type of pump is also referred to as a centrifugal pump, and the impeller is referred to as a radial impeller. In order to avoid a flow of liquid from the pressure side back to the suction side, which significantly reduces the efficiency of the centrifugal pump, a hydraulic bypass is provided between the suction side and the pressure side, the impeller being sealed towards the pump housing. This can be achieved substantially axially or radially. In the case of an axial seal, the sealing ring bears against the axially outer edge of the inlet connection. Due to the axial forces acting on the pump shaft in operation toward the intake side, due to hydraulic shocks in the pipe system connected to the pump and/or due to the mechanical drive of the centrifugal pump, the axial sealing rings usually also act at the same time as axial bearing supports and are therefore subject to high wear. A radial seal of the intake pipe connection is therefore generally preferred, wherein the suction ring bears sealingly radially on the outside circumference of the intake pipe connection.

Here, the quality of the seal between the pressure side and the suction side of the centrifugal pump also has a significant impact on the hydraulic efficiency. In order to keep losses low, it is desirable to keep the clearance between the impeller and the pump housing as small as possible. Since the hydraulic forces can lead to a bending of the shaft and thus to a reduction of the clearance, suitable margins have to be taken into account when dimensioning. So-called wear rings (the english term "wear rings") are often used as suction rings, in which the clearance is made smaller when the shaft is bent, intentionally receiving the contact of the impeller with the wear ring. Ideally, the operating clearance decreases after a certain time. To avoid clogging, a minimum clearance is also required here in connection with manufacturing. However, this places high demands on the precision of the assembly during manufacture and assembly.

The larger the centrifugal pump and its corresponding components, the more applicable this applies. Thus, for example, in the case of so-called split pumps, wear rings having a nominal diameter of 500mm or more are used. The axial two-piece bearing blocks weigh up to one ton and therefore need to be hoisted by a crane during installation. It is also contemplated that the wear ring wears during operation and that over time the radial clearance between the wear ring and the inlet fitting increases. Therefore, the efficiency of the centrifugal pump decreases, and the pump characteristic curve moves in a direction of lower rotation speed. To avoid this, the wear rings must be periodically serviced and replaced if necessary. The extremely high wear also requires premature replacement.

Maintenance or replacement of wear rings requires a significant amount of labor and time and typically results in a long period of shutdown of the centrifugal pump, typically requiring at least one or two days. In this case, the electric drive first needs to be decoupled from the pump. To be removed, the pumped liquid must also be drained from the pump housing. The pump housing must then be disassembled and the upper housing part can be removed by a crane. The pump shaft and impeller must then be disassembled to access the wear ring.

SUMMERY OF THE UTILITY MODEL

It is therefore an object of the present invention to provide a centrifugal pump with an improved radial inlet pipe connection seal, in which on the one hand the sealing gap can be adjusted very precisely to a minimum and on the other hand the maintenance costs are significantly reduced.

This object is solved by a centrifugal pump with an improved siphon seal. Advantageous embodiments are explained in the following.

According to the utility model discloses, a centrifugal pump unit is proposed, it includes pump casing and at least one impeller of arranging in the pump casing for carrying liquid, this impeller has the intake-pipe connection, and this intake-pipe connection seals through grooved wear ring, and wherein the pump casing has the adjustment unit, can adjust the diameter of wear ring through this adjustment unit. The core of the invention is therefore the sealing by means of an adjustable and adjustable air inlet pipe connection. By means of adjustability or adjustability, the radial seal of the intake manifold connection can be set to a minimum clearance after assembly of the pump on the one hand and can be readjusted to a minimum clearance in the event of maintenance or repair on the other hand. As a result, the void losses can be significantly reduced and thus higher efficiencies are achieved again. The wear ring no longer needs to be replaced due to adjustability.

In the following, the term "adjustment" is used not only for the initial setting after the pump assembly, but also for "readjustment" after a corresponding number of hours of operation. The sealing arrangement may be performed during operation of the pump. For this adjustment, the centrifugal pump does not need to be removed or dismantled from the connected hydraulic system. Thus, maintenance costs are significantly reduced and downtime is avoided to a large extent, at least minimized.

The slotted wear ring is interrupted by a slot at least one location of its circumference such that opposite circumferential ends of the wear ring are spaced apart. This distance makes it possible to change the inner diameter of the wear ring, which is achieved according to the invention by the adjusting unit. By reducing the diameter, the circumferential ends are moved towards each other, making the groove smaller.

Suitably, the wear ring has only one groove, so that it is integrally formed, facilitating handling when assembling the inlet fitting seal and simplifying the overall design, since only one position of the wear ring is required to take measures to prevent flow through the groove, as will be explained later. Thus, in the one-piece embodiment variant, the wear ring has substantially a C-shape. However, the perimeter of the slot is much smaller than a typical C-shape. For example, the circumferential width of the groove is between 0.5% and 3% of the circumference.

In principle, however, the wear ring can also be slotted a plurality of times. This means that the wear ring consists of two or more annular segments, the distance of the grooves being formed between each annular segment. In this embodiment variant, the sum of the grooves has a width in the circumferential direction of between 0.5% and 3% of the circumference. In this case, it is reasonable that the grooves are of the same size, so that for n grooves the width of each groove in the circumferential direction is between 0.5/n% and 3/n% of the circumference.

Preferably, the adjustment unit is arranged to apply a radially inward force to the outer circumference of the wear ring. This results in a radial compression of the wear ring with a corresponding adaptation of the wear ring diameter to the outer diameter of the intake pipe connection of the impeller. The sealing clearance between the wear ring and the inlet pipe connection can thus be reduced to a minimum, theoretically even to 0 mm.

For example, the wear ring may be constructed of metal, such as bronze, gray cast iron, or stainless steel, or may be constructed of plastic, such as PTFE.

According to an advantageous embodiment variant, the adjustment unit has an outer ring and an inner ring with a circular spline connection between them, wherein the outer ring is adjustable at an angle in the circumferential direction relative to the inner ring, the diameter of the inner ring is reducible and the wear ring bears against the radially inner side of the inner ring. Thus, the outer ring forms the outer part of the circular spline connection and the inner ring forms the inner part of the circular spline connection. In this case, the inner circumference of the outer ring has a circular spline profile and the outer circumference of the inner ring is a complementary circular spline profile.

An inherent feature in a circular spline connection is that the two rings are pressed against each other due to their rotation relative to each other. The forces in the round spline connection act radially on the connection partner. The outer ring exerts a radially inward force on the inner ring. This results in a reduction of the inner diameter of the inner ring, which in turn transmits the force to the wear ring, so that its inner diameter likewise becomes smaller and the sealing gap is reduced. This has the advantage that a more precise adjustment of the gap is achieved over the entire circumference, and the readjustment of the sealing gap is particularly simple.

Preferably, the outer ring is integrally formed. It is hereby achieved that the torque acting on the circumferential point acts on the entire ring in order to rotate it. This has the following advantages over the multi-part design of the outer ring: the forces and rotational movements do not have to be transmitted first to the components of the outer ring by suitable means. The design of the adjustment unit is thereby particularly simple. The integrally formed outer ring then has along its inner circumference the circular spline profile in the form of at least one circular spline. Thus, the inner circumference may have a single, two or more circular splines.

In order to be able to reduce the diameter of the inner ring, the inner ring may be made of a compressible material, for example an elastomer. Thus, the inner ring is elastic and deforms due to the radially inward force. In this case, however, it should be noted that the elasticity must be long, in particular for several years, so that suitable requirements are placed on the material.

To avoid this problem, the inner ring can be made of a shape-stable material, in particular of metal or plastic. However, in order to be able to achieve a reduction in diameter, it is necessary here to provide for the inner ring to be slotted such that a gap exists between two respective circumferential ends in the circumferential direction. Then, due to the reduction in diameter, these circumferential ends move towards each other and reduce the gap. It should be noted that the terms groove and void are technically the same, however, in the context of the present invention, the term "void" is used for the inner ring and the term "groove" is used for the wear ring.

In an embodiment variant, the inner ring may be formed by only one circular section. Thus, the inner ring is one piece and therefore has only one gap in its circumferential direction. The inner ring is substantially C-shaped. At least one circular spline complementary to the outer ring is correspondingly formed along the outer circumference of the circular section to mate with the at least one circular spline of the outer ring. Thus, in one sub-variation, a single complementary circular spline may be formed along the outer circumference of the circular section forming the inner ring. Alternatively, in another sub-variation, there may be two or more circular splines along the outer circumference of one circular section forming the inner ring.

According to another embodiment variant, the inner ring may be formed by an annular arrangement of two or more circular segments. It is therefore multipart and suitably has a gap between two adjacent circular segments on each of its circumferences. At least one circular spline complementary to the outer ring is correspondingly formed along the outer circumference of the circular section to mate with the at least one circular spline of the outer ring. Thus, in one sub-variation, a single complementary circular spline may be formed along the outer circumference of all circular sections forming the inner ring. Thus, the circular section is also a section of a complementary circular arc wedge and together form the one complementary circular spline. In another sub-variant, there are two or more complementary circular splines along the outer circumference of all circular sections forming the inner ring.

Ideally, the number of circular sections of the inner ring is equal to the number of circular splines of the outer ring or to the number of complementary circular splines. The distribution of the complementary round splines can preferably be realized here such that each round section on its back, that is to say its radial outside, is exactly one complete complementary round spline of the round spline-shaped connection. The manufacture of the circular segments is simplified because the jump in height from one circular spline to the next is not within the circular segment.

It is particularly advantageous if the circular spline connection between the outer ring and the inner ring consists of three circular splines and three complementary circular splines. Thereby a self-centering effect of the round spline connection is achieved.

Thus, in a preferred embodiment variant it may be provided that three circular splines are formed along the inner circumference of the outer ring, while the inner ring is formed by an annular arrangement of three circular spline sections, the respective outer circumferences of which are distributed to form circular splines that are fully complementary to the circular splines of the outer ring.

It should be noted that the inner ring can be dimensionally stable in both the one-piece and segmented, multipart embodiment variants, in particular made of metal or plastic, but can alternatively also be elastic, in particular made of elastomer.

Preferably, the circular section of the inner ring remains radially movable. This simplifies assembly and ensures a defined movement. Furthermore, the inner ring is prevented from rotating in the circumferential direction by the fastener and the circular spline connection is thereby tightened or loosened. If the impeller starts from the wear ring in good time, it is carried along by the forces, which in turn carries along the inner ring.

In the circumferential direction, the circular section is in particular stationary relative to the pump housing, so that the inner ring does not rotate when the outer ring is pivoted. Therefore, in order to pivot the outer ring relative to the inner ring, a minimum adjustment angle is required on the outer ring.

In one embodiment variation, the outer ring may be pivotally engaged with an L-shaped support ring secured to the pump housing. The support ring thus engages around the outer ring on the outer circumferential side and the axial end face and holds it in place. Thus, the outer ring may also pivot relative to the support ring and slide therein.

In order to fix the circular section in the circumferential direction and at the same time to remain radially movable, the support ring may have axially projecting guide pins which engage with corresponding recesses in the circular section. The recess may be a groove or a slot, for example. The groove or slot may extend substantially radially or along the cut line so that the entire section may move radially. Suitably, the guide pins are equally circumferentially distributed. The guide pins may be formed, for example, by cylindrical pins. Preferably, the guide pins are screwed onto the support ring. Alternatively, the guide pins may be welded, brazed, pressed or glued to the support ring.

The grooves in the wear ring may have substantially any shape. The manufacture is particularly simple when the end edges of the circumferential ends are formed at right angles to the circumferential direction, so that the groove extends purely axially between the circumferential ends. The groove thus has an I-shape and a minimal longitudinal extension. Alternatively, the longitudinal extension of the groove may be at an angle unequal to 90 degrees to the circumferential direction. Furthermore, the circumferential ends may also be formed such that other groove shapes are obtained, such as V-shaped, U-shaped, Z-shaped, labyrinth-shaped or meandering-shaped grooves. It should be noted here that the more complex the design of the groove, the better the tightness of the groove.

It can be said that a part of the pumped liquid can flow from the pressure side to the suction side on the impeller through the groove, since the groove forms a bypass between the suction side and the pressure side of the impeller. In order to prevent such a flow, it is advantageous to have blocking means in the groove, that is to say in particular sealingly between the circumferential ends of the wear-resistant rings. For example, the blocking means may be an elastic sealing element. The blocking means will then be squeezed as the diameter of the wear ring decreases, so that the groove is always tight.

According to an alternative embodiment, the blocking means is a thumb screw, the opposite wings of which extend into elongated recesses at the circumferential ends in the normal mounted state. The recesses simultaneously form a guide in the circular movement of the circumferential ends and hold them in place by a form fit with the thumb screws.

Preferably, the locking device, in particular a thumb screw, is screwed in particular into a hole of one of the circular sections. Thus, there is a strong connection between the wear ring and the inner ring, which prevents relative movement between the wear ring and the inner ring, particularly when the impeller on the wear ring is started. Thus, in combination with the guide pins attached to the support ring, the overall arrangement of the adjustment unit and the wear ring is fixed against rotation in the circumferential direction.

Advantageously, the circular sections are formed identically. In this case, it is not necessary to distinguish between different types of circular sections, in particular between a hole with a locking means and a hole without such a hole, when assembling the adjustment unit. All circular segments therefore have corresponding holes for the locking means, however, only one of these holes is used in a simply slotted wear ring, the others are not used. However, in the case of two or three slotted wear rings, other holes may be used for the second and third locking means, which locking means are then correspondingly placed in the respective second or third slots.

Suitably, the centrifugal pump comprises a handling means for pivoting the outer ring relative to the inner ring. Ideally, the manipulating device is accessible from outside the pump housing, and corresponding tools can be used, so that the pump assembly is not costly to disassemble.

According to one embodiment variant, the handling device may comprise a pin projecting radially from the outer ring and a screw inserted in the pump housing, preferably arranged tangentially thereto in a threaded hole, which screw is held in operative connection with the pin such that the screwing depth of the screw determines the angular position of the pin. In this case, the screw can be rotatably inserted from outside the pump housing. The operating principle of the operating device is as follows: for example, the screw, which may be a grub screw, is pressed more and more backwards (from the screw's point of view) as the depth of engagement increases, where its angular position changes and the outer ring pivots. This means that the outer ring or pin is in an initial state in an initial pivoted position, which is remote from the pivoted position when the screw is pushed deeper into the threaded hole.

According to an alternative embodiment variant, the handling device may comprise: a gear or worm wheel portion, preferably arranged on or forming part of the outer circumference of the outer ring; and a helical worm engaged into the gear or worm wheel portion. In this case, the worm can be rotatably inserted from outside the pump housing. The operating principle of the operating device is similar to that mentioned previously. However, instead of a screw, here a worm is rotated, the rotation of which, as in a worm gear, causes a longitudinal movement of the gear wheel or the worm wheel part with the extension of the worm, thereby changing the angular position of the outer ring. Likewise, the outer ring or pin is also in an initial pivoted position in the initial state, which is away from when the worm screw is turned.

The wear ring forms a preassembled, in particular replaceable, component together with the adjustment unit or at least a part thereof, in particular together with the inner ring, the outer ring, the support ring and the pin or gear or worm wheel part, hereinafter referred to as intake manifold joint seal arrangement unit, so that the replacement of the wear ring during assembly and maintenance of the centrifugal pump can be carried out simply and quickly.

The reduced efficiency of centrifugal pumps is manifested not only in the wear rings which are worn, but also in the impeller which is damaged by cavitation. In the latter case, of course, the sealing clearance between the impeller and the wear ring is not adjusted, so that the impeller needs to be replaced. In order to determine the cause of the efficiency reduction and to avoid taking erroneous maintenance measures, it can be provided that the pump housing has a sealable inspection opening, which opens into the suction chamber in front of the impeller, for the purpose of inspecting the gap between the wear ring and the impeller to carry out a flexible endoscope. If the gap is normal, the assumption of impeller damage is close. Furthermore, the endoscope may help to achieve precise adjustment of the sealing gap.

In one embodiment variant, the centrifugal pump can have a second impeller with a further inlet pipe connection. In a further embodiment variant, the impeller may be double-flow and have a further inlet connection opposite the inlet connection. In both variants, the other intake pipe connection can also be sealed radially to the pump housing by a corresponding second slotted wear ring, and the pump housing has a corresponding second adjustment unit, by means of which the diameter of the second wear ring can be opened or readjusted. The second wear ring and/or the second adjustment unit may have the same features, characteristics and advantages as previously described in relation to the first wear ring or in relation to the first adjustment unit.

The invention is preferably used for so-called split pumps. In this way, the pump housing can be axially separated, in particular by the upper housing part and the lower housing part, preferably such that the rotational axis of the pump shaft is located within the separating plane between these two housing parts.

The utility model discloses still relate to a centrifugal pump assembly, this centrifugal pump assembly includes according to the utility model discloses a centrifugal pump and the electric drive unit who is used for driving centrifugal pump unit. For this purpose, the drive shaft of the drive unit is mechanically coupled to the pump shaft and drives an impeller mounted on the shaft.

Drawings

Further features, characteristics and advantages of the invention will be described below with reference to exemplary embodiments.

Wherein:

fig. 1 shows a vertical axial section of a centrifugal pump according to the invention;

fig. 2 shows a radial section through the intake pipe connection of the impeller of the centrifugal pump according to fig. 1;

fig. 3 shows a radial cross-sectional view of the intake pipe sealing structure unit of the centrifugal pump according to fig. 1 without the pump housing;

fig. 4 shows a view of the interior of the wear ring according to the direction X in fig. 3;

fig. 5 shows an axial cross-section of the air intake nipple sealing structure unit according to section line E-E in fig. 3.

Detailed Description

Fig. 1 shows a centrifugal pump 50 for conveying liquids in the design of a so-called split pump, which has a pump housing 1 of the spiral design type divided horizontally along a rotational axis 18 into an upper housing part 1a and a lower housing part 1 b. The housing parts 1a, 1b abut each other at a parting plane 9 (see fig. 2). The impeller 2 is arranged in the pump housing 1, which impeller is rotatably mounted on the pump shaft 4 by means of a shaft protection 46 (see fig. 2) having an annular groove 47. The pump shaft 4 is driven by an electric drive unit, not shown, wherein a clutch or transmission is present between the pump shaft 4 and the drive shaft, in order to enable separate mounting and assembly of the two devices. The centrifugal pump 50 and the drive unit together form a centrifugal pump assembly. The weight of the housing parts 1a, 1b is very large, the total weight being up to one ton, so that the mounting and dismounting of the centrifugal pump 50 must be carried out with a crane.

The impeller 2 divides the interior of the pump housing 1 into a suction side 5 from which the impeller 2 sucks in the liquid to be pumped and a pressure side 7, which pressure side 7 is connected to the spiral chamber 3 located radially outside the pump impeller 1. In the region of the spiral chamber, the pump housing 1 forms a spiral housing 3 a. The impeller 2 accelerates the liquid and jets it tangentially, wherein the spiral chamber 3 guides the liquid to the pressure side 7.

In this embodiment variant, the impeller 2 is double-flow. This means that the impeller is constructed substantially mirror-symmetrically and has two suction nozzles 5 opposite one another, through which the impeller 2 sucks in the liquid. Due to the symmetry of the impeller 2, the pump housing 1 is also designed substantially symmetrically with respect to the plane of symmetry of the impeller 2. In contrast to conventional impellers of the radial design, the impeller blades 12 extend here in the axial direction on both sides of the respective suction nozzle 5. The double-flow impeller 2 of the embodiment variant described herein has no support disk on which the blades are normally arranged in the case of a single-flow impeller.

Instead, the blades 12 are covered on each side by a cover plate 10, which cover plate 10, starting from its substantially radial extension at the outer edge in the form of a radial disc, comes closer and closer to the pump shaft 4, viewed in cross section, in the form of an axial extension in the form of a cylindrical ring, the pump shaft 4 being concentric with the axis of rotation 18 and forming the boundary of the suction mouth 5 of the impeller 2. This cylindrical ring of the cover plate 10 forms the inlet pipe connection 10a of the impeller 2 and may be up to 500mm in diameter. The inlet pipe connection 10a must be sealed at its radial outside towards the pump housing 1 to prevent back flow (bypass) of liquid from the pressure side 3, 7 to the suction side 5 of the impeller. As this reduces the efficiency of the centrifugal pump 50 and affects the pump characteristics.

To this end, the present invention provides a wear ring 14, which with its inner circumference 14a is located outside the intake pipe connection 10a, wherein a sealing gap is provided between the intake pipe connection 10a and the wear ring 14. The wear ring 14 is made of metal, such as bronze, gray cast iron or stainless steel, or of plastic, such as PTFE.

Due to component and assembly tolerances, the sealing gap cannot be adjusted precisely and is usually not constant over the circumference, for example due to deflections of the shaft 4. Thus, in practice, it may result in the wear ring 14 resting partly on the suction nozzle 10a and not moving after commissioning. In addition, due to wear, the seal clearance becomes large and the efficiency is reduced at the time of operation, so that maintenance of the centrifugal pump 50 is required.

According to the present invention, the centrifugal pump 50 according to the present invention comprises an adjustment unit 20, 21, 29 which allows to adjust the sealing clearance accurately after assembling the centrifugal pump 50 and also after hours of operation, for example in case of proper maintenance or special service.

According to the invention, the setting or readjustment, hereinafter collectively referred to as "setting", of the sealing gap can be achieved by the inner diameter of the wear ring 14 being changed. For this purpose, the wear ring 14 is slotted and the adjustment units 15, 21, 29 are arranged to set the diameter of the wear ring 14. Thus, a settable and readjustable air inlet pipe joint seal is formed.

The wear ring 14 used herein is simply slotted, which is thus one piece and essentially has a C-shape. That is, the groove is interrupted by the groove 24 at only one position of its circumference, so that the two circumferential ends 27a, 27b of the wear ring 24 are spaced apart there, see fig. 4. This distance enables the inner diameter of the wear ring 14 to be changed to a certain extent, which is achieved according to the invention by the adjusting unit 20, 21, 29. For example, the width of the groove in the initial state may be between 0.5% and 3% of the circumference in the circumferential direction, for example 12.5 mm. By reducing the diameter, the circumferential ends 27a, 27b are moved towards each other so that the slot 24 becomes smaller.

Here, the adjustment units 15, 21, 29 are arranged to exert a radially inward force on the outer circumference of the wear ring 14, which results in a uniform radial compression of the wear ring 14 over the circumference and a corresponding reduction of the inner diameter of the wear ring, for example up to 4mm, depending on the size of the wear ring. The adjusting unit 15, 21, 29 can be seen clearly in fig. 2 and 3, which fig. 2 and 3 show a radial section through the intake pipe connection 10a in the region of the siphon seal.

The adjusting unit 15, 21, 29 here essentially comprises an outer ring 21, an inner ring 15 and a handling device 29. There is a circular spline connection between the outer ring 21 and the inner ring 15, and the outer ring 21 is angularly adjustable in the circumferential direction relative to the inner ring 15, which can be achieved by means of a handling device 29. The outer ring 21 and the inner ring 15 are made independently of each other of metal, in particular stainless steel, or of plastic, for example PTFE, and are in any case stable in shape. The surfaces of the outer ring 21 and the inner ring 15 facing each other are at least smooth or have an even lower surface roughness in order to minimize friction between the circular splines during pivoting of the outer ring 21.

The inner circumference 21a of the inner ring 21 carries a circular spline profile in the form of three complementary circular splines. Each circular spline is clearly discernible at its stepped transition, since the radial thickness of the outer ring 21 increases in the circumferential direction to a maximum and springs back gradually to a minimum radial thickness at the beginning of the next circular spline. The outer ring 21 is one-piece and thus forms to some extent a splined ring.

Correspondingly, the outer circumference 15a of the inner ring 15 carries a complementary circular spline profile in the form of three complementary circular splines. The inner ring 15 is composed of several parts, i.e. is segmented, more precisely formed by three individual circular segments 15, which are arranged annularly. Three complementary circular splines are distributed on the circular segments 15 such that each circular segment 15 has a fully complementary circular spline on its outer circumference 15 a. The radial thickness of the circular section 15 increases in the opposite circumferential direction with respect to the outer ring 21.

The inner circumference 15b of the inner ring 15 is cylindrical. The wear ring 14 abuts against this inner circumference. Both the circular splines of the outer ring 21 and the circular splines of the inner ring 15 have a logarithmic spiral shape, thereby achieving a centering effect on the wear ring 14. The circular sections 15 are arranged spaced apart from each other to form a gap 19, so that the inner diameter can be reduced.

By pivoting the outer ring 21 in a counterclockwise direction relative to the inner ring 15, the inner circumference 21a of the inner ring 21 and the thinner end of the circular spline slide forward along the outer circumference 15a of the circumferentially fixed inner ring 15. The radial thickness of the outer ring 21, and thus also of the rings 15, 21, is thereby increased on the basis of the fixed circumferential point, so that the outer ring 21 exerts a radial force on the inner ring 15. The circular section 15 therefore deviates with the radial movement, resulting in a reduction of the inner diameter of the inner ring 15, which in turn transfers it to the wear ring 14, so that its inner diameter likewise becomes smaller. This enables the provision of a sealing gap.

The gap 19 becomes narrower due to the radial movement of the circular section 15. To prevent the inner ring 15 from rotating when the impeller 2 on the wear ring 14 is started and to reduce the wear ring 14, the circular section 15 is fixed in the circumferential direction but remains radially movable. For this purpose, substantially radially extending slots 17 are provided in the circular section 15, cylindrical guide pins 18 being provided in the slots 17. Instead of slots, slots may also be provided. Each circular section 15 has such a deep hole 17, wherein the deep holes are arranged equidistantly. Suitably, the deep hole 17 is formed in the portion of the circular section 15 having the greatest radial thickness. The length of the deep hole 17 is such that the circular section 15 may move radially up to 2 mm.

The guide pins 18 are fixed to the support ring 20, in particular screwed, welded, soldered, pressed or glued to the support ring. These guide pins extend substantially axially away from support ring 20. The support ring 20 is here formed as an L-shaped metal plate and thus comprises an axial hole disc-shaped portion 20a and a cylindrical portion 20b, as shown in fig. 5, fig. 5 being an axial sectional view of the air inlet pipe joint seal structure unit 45 along the section line EE in fig. 3 relative to the inner circumference 14a of the wear ring 14. The support ring 20 surrounds an outer ring 21 on the outer circumference, the outer ring 21 being correspondingly slidingly located in the support ring 20. Thus, the outer ring 21 can also pivot relative to the support ring 20, but is fixed in its movement in the axial direction. The hole-disk-shaped portion 20a, which covers the outer ring 21 at the axial end face and on its outer ring 21 points axially inward of the guide pin 18, serves for this purpose. The outer ring 21 is covered on the other axial end face by a press ring 48, which press ring 48 is pressed into a radial groove in the cylindrical portion 20 b. This radial groove is characterized in that the cylindrical portion 20b of the support ring 20 has a smaller radial thickness at the axial end, the support ring 20 thus surrounding the press ring 48 on the outer circumference.

The support ring 20 is held on the pump housing by a form fit with a blocking pin 23, the blocking pin 23 being part of the fastening bracket 22, in particular being formed at its circumferential end. The holder 22 is semicircular and rests against the outside of the support ring 20, see fig. 2. The support is fixedly connected to the pump housing 1 or to the lower housing part 1 b.

In the embodiment shown herein, the groove 24 in the wear ring 14 has an I-shape, as shown in fig. 4, fig. 4 showing a view from the inner circumference of the wear ring 14 according to the direction X of fig. 3. The grooves 24 extend at right angles to the circumferential direction, axially parallel to the axis of rotation 18. Thus, the end edges of the circumferential ends 27a, 27b are parallel to each other, at right angles to the circumferential direction. As shown in fig. 4, the outer ring 21 protrudes slightly behind the wear ring 14. Therefore, the axial length of the outer ring is greater. Instead, the inner ring 15 has the same axial length as the wear ring 14 and is visible through the groove 24.

In order to prevent the groove 24 from forming a bypass for the flowing-back liquid, that is to say from flowing through the groove 24, a blocking device 25 is provided in the groove 24. Here, the blocking means 25 are formed by a wing nut having two wings extending away from the shaft 28. In each of the two circumferential ends 27a, 27b, an elongated, open recess 26a, 26b is provided which extends in the circumferential direction and faces the respective end edge, into which recesses the wings of the wing nut 25 extend in a form-fitting manner, respectively. The recesses 26a, 26b serve to guide and prevent axial displacement of the circumferential ends 27a, 27 b. The length of the recesses 26a, 26b is equal to or greater than the length of the wings.

The thumb screw 25 is screwed with a shaft 28 having a corresponding external thread into a hole 16 having a corresponding internal thread in one of the circular sections. The wear-resistant ring 14 is thus fixedly connected to the inner ring 15 by means of the thumb screws 25. Thus, the integral arrangement of the adjustment units 15, 21, 29 and the wear ring 14 in combination with the guide pins 18 fixed to the support ring 20 ensures that no rotation in the circumferential direction occurs.

For the sake of simplicity of installation, it is not necessary to distinguish between the different circular sections 15, all circular sections 15 being formed identically. All circular sections 15 therefore have said holes 16 for blocking means, whereas in the embodiment variant shown herein only one of these holes 16 is used.

A part of the adjusting unit 15, 21, 29 is also an operating device 29 for pivoting the outer ring 21 relative to the inner ring 15. For this purpose, a pin 31 in the form of a monocular bolt projects radially from the outer ring 21, which pin extends through a recess 33 provided specifically for this purpose in the support ring 20 into the chamber 30 formed in the pump housing 1, 1 a. A ball and socket joint 32 is arranged in the eye of the monocular bolt 31, which ball and socket joint is connected to the axial end 35a of the screw 35, for example, positively, latchingly or by means of a thread. The ball-and-socket joint 32 enables compensation of the angle between the pin 31 and the screw 25 when the outer ring 21 is pivoted.

It should be noted that the ball and socket joint 32 can be replaced by a simple articulation, since here only an angular compensation in the spatial direction is necessary.

The screw 35 is embodied as a grub screw and is likewise part of the actuating device 29. The screw is located in a threaded hole 36, which threaded hole 36 is radially tangential or slightly offset, but extends parallel to the tangent of the mounting position of the pin 31. The screwing depth of the screw 35 therefore determines the angular position of the pin 31, since it is pressed with its axial end 35a against the pin 31.

It should be noted at this point that the connection between the hinge 32 and the screw 35 does not need to be fixed, since the pin 31 only needs to move in one direction. This movement is achieved when the screw 35 is screwed into the threaded hole 36 so that it strikes the pin 31 and is then also turned. If the screw 35 is subsequently turned back, it is merely moved away from the pin 31 and the outer ring 21 remains in the pivoted position. However, the advantage of a fixed connection, for example in the form of a positive connection (locked or threaded), over a loose connection is that a reversible adjustment, that is to say an adjustment in both directions, can be brought about, only a pivoting back of the outer ring 21 being possible again by a swiveling of this screw 35. This enables a modification of the arrangement, for example when the screw 35 is tightened too tightly, the wear ring 14 thus firmly surrounds the suction nozzle 10 a.

The threaded holes 36 are open to the outside so that the screws 35 can be accessed from outside the pump housing. The screw may be turned with a suitable tool without opening the pump housing 1, 1 a. The bore 36 is closed by a sealing plug 37, the sealing plug 37 being spaced apart to form a void 38 spaced from the grub screw 35. The plug 37 is removed to operate the operating device 29.

The operating device 29 operates on the principle that the screw 35 presses the pin 31 with increasing screw-in depth increasingly rearward, i.e. in the direction of the arrow in fig. 3, wherein its angular position changes and the outer ring 21 pivots. This means that the outer ring 21 and the pins 31 are in an initial state at an initial pivot position from which the outer ring 21 and the pins 31 are removed when the screws 35 are entered deeper into the threaded holes 36, as shown in fig. 2 and 3. The limitation of the angular adjustment can be achieved by a stop of the pin 31, for example by a recess 33 in the support ring 20 or by the wall of the chamber 30 reached by the pin at the maximum screwing depth of the screw 35. The possible angular adjustment range of the outer ring 21 is illustrated in fig. 3 by the dashed boundary line. The angular adjustment range may be between 0 ° and 15 ° or even between 0 ° and 20 °.

The wear ring 14, together with the inner ring 15, the outer ring 21, the support ring 20 and at least the pins 31 of the actuating device 29, form a pre-assembly and enable the assembly 45, i.e. the intake manifold joint seal assembly, to be replaced as required, so that the assembly of the centrifugal pump and the replacement of the wear ring during maintenance can be carried out simply and quickly.

Since the centrifugal pump 50 has an impeller 2 with two inlet connections 10a, such an inlet connection arrangement 45 is present in double correspondence, as is the case with the actuating devices 29, which can be actuated independently of one another. Thus, the wear ring 14 associated with the second inlet pipe joint 10a and/or the adjustment unit 15, 21, 29 associated with the second inlet pipe joint 10a have the same features, characteristics and advantages as they were previously described with respect to the wear ring 14 associated with the first inlet pipe joint 10a or with respect to the adjustment unit 15, 21, 29 associated with the first inlet pipe joint 10 a.

As explained in the introduction to the description, the reduction in the efficiency of the centrifugal pump 50 can be manifested not only on the worn wear ring 14 but also on the impeller 2 damaged by cavitation, so that the adjustment of the sealing aperture does not lead to an improvement. In the double-flow impeller 2 according to fig. 1, it is also noted that with two suction halves 10a and thus two sealing gaps, the wear rings 14 thereof can wear differently, so that only one of the two wear rings 14 needs to readjust the sealing gap.

It is therefore advantageous that the cause of the efficiency reduction can be determined without great expenditure. Returning to fig. 1, this fig. 1 shows a simple measure for finding the cause of the efficiency drop. A closable inspection aperture 43 is provided which opens into the suction chamber 5 in front of the impeller 2 in the pump housing 1, 1b and allows inspection of the sealed space with an endoscope 39. Such an endoscope 39 generally has a flexible tube 40 with a bowden cable for navigation and a side camera 42, and a monitor unit 41 for displaying images captured by the camera 42, which can be easily positioned through the inspection hole 43 and the impeller 2 in order to take photographs of the impeller 2 and the sealed space. Such inspection openings 43 can be located on both sides of the pump housing 1, 1b in the centrifugal pump 50 according to fig. 1, so that both sides of the impeller are accessible. The inspection aperture 43 is sealingly closed by a sealing element 44, which is preferably self-sealing.

If the size of the sealing gap is correct, the assumption of damage to the impeller 2 is close and its wings 12 can likewise be inspected with the endoscope 39. The endoscope 39 may also help to achieve a precise adjustment of the sealing gap, since it is visible through the photograph on the monitor unit 41 whether the sealing gap has to be reduced and to what extent it has to be reduced.

The foregoing examples are illustrative of the present invention only, and are not limiting. In particular, the application of the settable siphon seal according to the present invention is not limited to split pumps, as shown in fig. 1. More precisely, the siphon seal can be used in any centrifugal pump, in particular in any oil-free pump.

Claims (21)

1. A centrifugal pump (50), the centrifugal pump (50) having a pump housing (1, 1a, 1b) and at least one impeller (2) arranged in the pump housing (1, 1a, 1b) for conveying liquid, the impeller (2) having an inlet pipe connection (10a), the inlet pipe connection (10a) being radially sealed with respect to the pump housing (1, 1a, 1b) by means of a wear ring (14), characterized in that the wear ring (14) is slotted and the pump housing (1, 1a, 1b) has an adjustment unit by means of which the diameter of the wear ring (14) can be adjusted.

2. The centrifugal pump (50) of claim 1, wherein the adjustment unit is arranged to apply a radially inward force on the outer periphery of the wear ring (14).

3. Centrifugal pump (50) according to claim 1, characterized in that the adjustment unit has an outer ring (21) and an inner ring with a circular spline connection between the outer ring (21) and the inner ring, wherein the outer ring (21) is adjusted angularly in the circumferential direction with respect to the inner ring, the diameter of the inner ring can be reduced, and the wear ring (14) bears against the radially inner side of the inner ring.

4. The centrifugal pump (50) of claim 3, wherein the outer ring (21) is one-piece and at least one circular spline is formed along an inner circumference (21a) of the outer ring (21).

5. A centrifugal pump (50) according to claim 3, wherein the inner ring is formed by only one circular section or by an annular arrangement of two or more circular sections (15), wherein at least one circular spline complementary to the outer ring (21) is formed along the outer circumference (15a) of one circular section or all circular sections (15).

6. Centrifugal pump (50) according to claim 5, characterized in that the circular section (15) is held radially movably.

7. Centrifugal pump (50) according to claim 5, characterized in that the outer ring (21) is pivotably engaged with an L-shaped support ring (20) fixed on the pump housing (1, 1a, 1 b).

8. Centrifugal pump (50) according to claim 7, characterized in that the support ring (20) has axially projecting guide pins (18), which guide pins (18) engage with corresponding recesses in the circular section (15).

9. Centrifugal pump (50) according to claim 8, characterized in that the recess has the form of a slot (17) or groove.

10. Centrifugal pump (50) according to claim 8, characterized in that in the groove (24) between the circumferential ends (27a, 27b) of the wear ring (14) there are blocking means (25) for preventing flow through the groove (24).

11. Centrifugal pump (50) according to claim 10, characterized in that the blocking means (25) is a wing nut, the opposite wings of which in the normally mounted state extend into elongated recesses in the circumferential ends (27a, 27 b).

12. Centrifugal pump (50) according to claim 10, characterized in that a blocking means (25) is inserted in the hole (16) of one of said circular sections (15).

13. Centrifugal pump (50) according to claim 12, characterized in that the blocking means are screwed to the hole (16) of one of the circular sections (15).

14. Centrifugal pump (50) according to claim 5, characterized in that the circular sections (15) are identically formed.

15. A centrifugal pump (50) according to claim 3, characterized by a handling device (29) for pivoting the outer ring (21) relative to the inner ring.

16. Centrifugal pump (50) according to claim 15, characterized in that the handling means (29) comprise pins (34) radially projecting from the outer ring (21) and screws (35) inserted in threaded holes (36) in the pump housing (1, 1a), the screws (35) remaining in operative connection with the pins (34) so that the screwing depth of the screws (35) determines the angular position of the pins (34).

17. Centrifugal pump (50) according to claim 16, wherein the screw (35) is rotatably accessible from outside the pump housing (1, 1 a).

18. The centrifugal pump (50) of claim 1, wherein the wear ring (14) together with the adjustment unit form a pre-assembled, replaceable assembly.

19. The centrifugal pump (50) according to claim 1, characterized in that the pump housing (1, 1a, 1b) has a sealable access hole (43) opening into the suction chamber (5) in front of the impeller (2) for the purpose of inspecting the clearance between the wear ring (14) and the impeller (2) to perform a flexible endoscope (39).

20. A centrifugal pump (50) according to any one of claims 1-19, wherein the pump housing (1a, 1b) comprises an upper housing part and a lower housing part, such that the rotational axis (8) of the pump shaft (4) is located within a separation plane (9) between the two housing parts.

21. A centrifugal pump assembly, characterized in that it comprises a centrifugal pump (50) according to any one of the preceding claims and an electric drive unit for driving the centrifugal pump (50).

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