DE202024106226U1 - Seal for a submersible pump motor with an axial shaft - Google Patents

Abstract

Cartridge-like sealing cassette (1) for a submersible motor (3) of a pump (4) having an axial shaft (2), comprising
a lower mechanical seal (5) arranged to separate waste water from a cooling liquid of a cooling circuit of the submersible motor (3) transporting heat from a stator (7) of the submersible motor (3) to a heat exchanger flange (8),
an upper mechanical seal (6) arranged to separate the cooling circuit from air present in a motor housing (9) of the submersible motor (3), and
a counter ring (10) provided axially between the lower mechanical seal (5) and the upper mechanical seal (6) and seated on the shaft (2) in a rotationally fixed manner, wherein
the counter ring (10) has an impeller (11) arranged to circulate the cooling liquid.

Description

technical field

The invention relates to a seal for a submersible motor of a pump having an axial shaft, comprising a lower mechanical seal, an upper mechanical seal and a counter ring provided axially between the upper mechanical seal and the lower mechanical seal and seated on the shaft in a rotationally fixed manner.

Background of the invention

Dry-installed submersible motors for sewage pumps in particular have an internal cooling circuit that transports heat from a stator of the submersible motor to a heat exchanger flange. The heat exchanger flange is in contact with sewage and transfers the heat dissipated in this way to the sewage in order to cool it.

Such submersible motors known from the prior art regularly comprise a first mechanical seal to separate the waste water from water and/or glycol of the internal cooling circuit, a second mechanical seal to separate the internal cooling circuit from air present in a motor housing of the submersible motor, and a counter ring provided between the first mechanical seal and the second mechanical seal.

The problem with such designs, however, is that replacing the mechanical seals and the counter ring due to wear is often not possible without dismantling the submersible motor, which means a considerable amount of work. In addition, the cooling circuit in the known designs needs improvement. Furthermore, the designs are often axially stretched, which leads to considerable bending and corresponding wear on the submersible motor shaft.

Description of the Invention

Based on this situation, it is an object of the present invention to improve a seal for a submersible motor of a pump, in particular a sewage pump, having an axial shaft.

The object of the invention is achieved by the features of the independent claims. Advantageous embodiments are specified in the subclaims.

Accordingly, the object is achieved by a cartridge-like sealing cassette for a submersible motor of a pump having an axial shaft, comprising
a lower mechanical seal arranged to separate waste water from a cooling liquid of a cooling circuit of the submersible motor transporting heat from a stator of the submersible motor to a heat exchanger flange,
an upper mechanical seal arranged to separate the cooling circuit from air present in a motor housing of the submersible motor, and
a counter ring provided axially between the upper mechanical seal and the lower mechanical seal, which can be seated on the shaft in a rotationally fixed manner, whereby
the counter ring has an impeller designed to circulate the cooling liquid.

An essential aspect of the proposed solution is that the lower mechanical seal, the upper mechanical seal and the counter ring are integrated as a functional group as a cartridge-like seal cassette and can thus be easily replaced as a whole, in particular without dismantling the submersible motor. By providing the aforementioned functional group as a cartridge-like seal cassette, a more compact design can be achieved, which leads to a shorter shaft end, i.e. to a smaller axial extension, and thus to less shaft bending, which results in less wear on the impeller and greater tightness. Ultimately, the proposed solution is more robust than the designs known from the prior art and in particular represents a pre-assembled and tested unit, which also reduces the risk of fiber blockages around the lower mechanical seal and/or upper mechanical seal. Finally, the integrated impeller allows the cooling liquid of the cooling circuit to circulate more effectively for better cooling of the submersible motor.

Within the scope of the invention, the term cartridge-like is to be understood in particular functionally as a container for interchangeable insertion into the submersible motor. Likewise, within the scope of the invention, the term cassette is to be understood in particular as box-like, modular and/or compact. This means in particular that the cassette can be inserted into the submersible motor as a unit and can be removed from it again. Within the scope of the invention, the term axial or radial refers in particular to the shaft, namely to its axial or radial extension.

A pump is generally a fluid machine that uses a rotary motion and dynamic forces to convey liquids, mainly as a fluid. In addition to a tangential acceleration of the fluid, also called medium, centrifugal force occurring in radial flow is used for conveying, so that Pumps can also be referred to as centrifugal pumps or rotary pumps. The fluid preferably comprises water or another liquid medium, such as waste water. The pump can be designed as a waste water pump, although other designs as a heating pump or as a borehole pump are fundamentally conceivable. The pump can also be designed as a multi-stage pump for increasing pressure or as a so-called vertical turbine. The pump can have a pump impeller which is provided in a pump housing that can be driven by the submersible motor that can be arranged in the motor housing. The shaft connects in particular the submersible motor to the pump impeller. In the context of the invention, a submersible motor is understood to mean in particular a motor that is designed and/or specified for operation completely submerged in a liquid such as waste water.

The lower mechanical seal, the upper mechanical seal and/or the counter ring preferably have a circular shape in axial plan view, which has at least one circular inner cross section and preferably also a circular outer cross section. Preferably, an inner diameter of the counter ring is smaller than an inner diameter of the lower mechanical seal and/or the upper mechanical seal. The lower mechanical seal and the upper mechanical seal can have the same inner diameter and/or be designed symmetrically. More preferably, the lower mechanical seal, the upper mechanical seal and/or the counter ring have a rectangular shape in the radial cross section.

The cooling liquid can comprise water and/or glycol. The impeller preferably has a plurality of impeller blades for circulating the cooling liquid. The sliding ring preferably lies in contact with the shaft, while the lower mechanical seal and/or the upper mechanical seal are spaced apart from the shaft with their inner side. The shaft is preferably connected to the submersible motor in a rotationally fixed manner. The impeller is preferably connected to the counter ring in a rotationally fixed manner. The impeller preferably has an opening into which the counter ring is inserted, i.e. the impeller preferably surrounds the counter ring radially all the way around. The lower mechanical seal and the counter ring and/or the upper mechanical seal and the counter ring preferably lie in axial contact with one another, can rotate relative to one another and/or are fluid-tight.

The seal cassette can preferably be inserted into the submersible motor with the upper mechanical seal at the front. The submersible motor is preferably arranged in the motor housing, which further preferably extends in the direction of the upper mechanical seal when the seal cassette is inserted into the submersible motor. The mechanical seal preferably sits on the shaft in a rotationally fixed manner.

According to a preferred development, the seal cassette has a base body, wherein the upper mechanical seal, the lower mechanical seal and the counter ring are arranged within the base body. Preferably, the aforementioned components are held within and by the base body, so that the seal cassette can be easily inserted into the submersible motor as a compact component and removed from it again. The base body, the lower mechanical seal, the sliding ring, the upper mechanical seal and/or the impeller are preferably made of metal and/or a hard plastic. Preferably, the base body projects radially beyond the lower mechanical seal, the sliding ring, the upper mechanical seal and/or the impeller, while the base body does not project axially beyond at least the upper mechanical seal. At its end facing the lower mechanical seal, the base body can have an inner collar that radially encloses the lower mechanical seal and does not project axially beyond it. In addition, the base body can have an outer collar that projects axially beyond the inner collar.

According to a further preferred embodiment, the seal cassette has an upper spring element and/or a lower spring element, wherein the upper spring element is arranged between the base body and the upper mechanical seal, exerting an upper spring force acting in the axial direction on the upper mechanical seal, and/or the lower spring element is arranged between the base body and the lower mechanical seal, exerting a lower spring force acting in the axial direction on the lower mechanical seal. The upper mechanical seal and/or the lower mechanical seal preferably has a collar extending radially outward, on which one end of the upper spring element and/or the lower spring element rests. Another opposite end of the upper spring element and/or the lower spring element preferably rests on the base body.

Preferably, an axially extending recess is provided in the base body, in which the other end of the upper spring element and/or the lower spring element is held. Further preferably, the base body surrounds the collar radially, so that the upper mechanical seal and/or the lower mechanical seal is limited in its axial movement by the base body. The upper mechanical seal, the slide ring and the lower mechanical seal are axially held against each other in the base body, in particular axially fluid-tight sealed and/or centered. Preferably, a plurality of upper and lower spring elements are provided, which are arranged at regular intervals around the upper and lower mechanical seals.

According to another preferred development, the seal cassette is provided with an upper seal and/or a lower seal, wherein the upper seal is arranged radially between the base body and the upper mechanical seal and/or the lower seal is arranged radially between the base body and the lower mechanical seal. The upper seal and/or the lower seal is preferably inserted into a radially inward-reaching groove in the base body. The upper seal and/or the lower seal is preferably designed as an O-ring seal or has a rectangular radial cross-section.

According to a further preferred embodiment, the seal cassette is provided with an upper anti-twist device, in particular designed in the form of a pin, which is guided axially through the base body and the upper mechanical seal, and/or a lower anti-twist device, in particular designed in the form of a pin, which is guided axially through the base body and the lower mechanical seal. The anti-twist device is preferably held stationary with one end in the axially extending recess and slides with its other opposite end in an opening extending axially in the collar. A plurality of anti-twist devices are preferably provided, which are arranged at regular intervals around the upper or lower mechanical seal. The anti-twist device holds the base body in a rotationally fixed manner to the upper mechanical seal and/or the lower mechanical seal.

According to another preferred development, the base body is designed to be open on its side facing radially away from the upper mechanical seal and/or the lower mechanical seal for the circulation of the cooling liquid. For this purpose, a plurality of openings can be provided on the radially opposite side through which the cooling liquid can be moved through the impeller and can circulate accordingly.

According to a further preferred embodiment, the base body has at least two rings and webs that extend axially between the rings and keep the rings spaced apart. Preferably, three rings are provided, with one ring each arranged radially corresponding to the upper mechanical seal, the mechanical ring, the impeller and the lower mechanical seal. The base body can be designed in one piece, but it is also possible for one of the rings to be designed in two pieces such that the base body can be placed in two parts on the upper mechanical seal, the mechanical ring and the lower mechanical seal, in particular in the axial direction, and when placed, the two parts are connected to one another to form the base body in a particularly detachable manner. The connection can be made by means of a screw or the like. Preferably, a plurality of webs are provided, which are arranged at regular intervals.

According to another preferred development, the counter ring has at least one, in particular two, sealing sleeve(s) which are inserted radially into the counter ring and can be seated on the shaft in a rotationally fixed manner. The sealing sleeve is preferably inserted into a circumferential groove extending radially outward on an inner side of the counter ring. The sealing sleeve preferably rests against the shaft in a touching manner. Further preferably, at least two sealing sleeves are provided which are arranged axially spaced from one another.

According to a further preferred embodiment, the upper mechanical seal and/or the lower mechanical seal has an outer support ring facing the counter ring and/or the counter ring has an inner support ring facing the upper mechanical seal and/or the lower mechanical seal. The counter ring particularly preferably has two inner support rings which are provided on opposite axial sides of the counter ring. The outer support ring and the inner support ring preferably lie against one another in a touching and/or fluid-tight manner. An axially extending groove, into which the outer support ring and/or the inner support ring is inserted, is particularly preferably inserted into an axial side of the upper mechanical seal and/or the lower mechanical seal facing the counter ring and/or into an axial side of the counter ring facing the upper mechanical seal and/or the lower mechanical seal.

According to another preferred development, the outer support ring and/or the inner support ring is made of silicon carbide. Silicon carbide, common name carborundum, is a chemical compound of silicon and carbon that belongs to the group of carbides. Silicon carbide ensures a high level of tightness and good rotatability between the upper mechanical seal and/or the lower mechanical seal and the counter ring.

According to a further preferred embodiment, the outer support ring is axially inserted and/or shrunk into the upper mechanical seal and/or the lower mechanical seal and/or the inner support ring is axially inserted and/or shrunk into the counter ring. The art, the outer support ring and/or the inner support ring adheres particularly well to the upper mechanical seal and/or the lower mechanical seal and/or to the mechanical ring.

According to another preferred development, the sealing cassette is provided with a fixing device which extends radially through the counter ring and is designed to fix the impeller in place on the counter ring. The fixing device is preferably designed as a screw, in particular as a headless Allen screw, which can be screwed into a radially extending thread in the counter ring in order to exert a radial force on the impeller for the purpose of fixing it.

The object of the invention is further achieved by a submersible motor pump, comprising the seal cassette as described above, the shaft and the submersible motor, wherein the impeller is seated on the shaft in a rotationally fixed manner. The submersible motor pump preferably has an opening into which the seal cassette can be inserted. The seal cassette preferably has a circular outer cross-section, the diameter of which tapers from the lower mechanical seal to the upper mechanical seal. The opening preferably corresponds to an outer shape of the seal cassette.

Short description of the drawings

The invention is explained in more detail below with reference to the accompanying drawings using preferred embodiments.

• 1 eine schematisch-perspektivische Seitansicht einer teilgeöffneten kartuschenartigen Dichtungskassette für einen eine axiale Welle aufweisenden Tauchmotor einer Pumpe gemäß einem bevorzugten Ausführungsbeispiel der Erfindung,
• 2 eine schematische Seitansicht der teilgeöffneten kartuschenartigen Dichtungskassette gemäß dem bevorzugten Ausführungsbeispiel der Erfindung,
• 3 eine schematische Schnittansicht der kartuschenartigen Dichtungskassette gemäß dem bevorzugten Ausführungsbeispiel der Erfindung,
• 4 eine schematische Draufsicht eines Laufrads der kartuschenartigen Dichtungskassette gemäß dem bevorzugten Ausführungsbeispiel der Erfindung, und
• 5 eine schematisch-perspektivische Seitansicht einer Gleitringdichtung der kartuschenartigen Dichtungskassette gemäß dem bevorzugten Ausführungsbeispiel der Erfindung.

In the drawings show

• 1 a schematic perspective side view of a partially opened cartridge-like sealing cassette for a submersible motor of a pump having an axial shaft according to a preferred embodiment of the invention,
• 2 a schematic side view of the partially opened cartridge-like sealing cassette according to the preferred embodiment of the invention,
• 3 a schematic sectional view of the cartridge-like sealing cassette according to the preferred embodiment of the invention,
• 4 a schematic plan view of an impeller of the cartridge-type sealing cassette according to the preferred embodiment of the invention, and
• 5 a schematic perspective side view of a mechanical seal of the cartridge-type sealing cassette according to the preferred embodiment of the invention.

Detailed description of the implementation examples

1 shows a schematic perspective side view of a partially opened cartridge-like sealing cassette 1 for a submersible motor 3 of a pump 4 having an axial shaft 2 according to a preferred embodiment of the invention, while 2 the cartridge-like sealing cassette 1 in a schematic side view which is partially opened and 3 which shows the cartridge-like sealing cassette in a schematic sectional view.

The cartridge-like sealing cassette 1 has, as shown 3 As can be seen, the pump has a lower mechanical seal 5 and an upper mechanical seal 6, which each surround the shaft 2 radially, but do not rest on the shaft 2. The lower mechanical seal 5 separates waste water from a cooling liquid of a cooling circuit, which serves to cool the submersible motor 3. By means of the cooling circuit, heat is transported from a stator 7 of the submersible motor 3, only indicated, to a heat exchanger flange 8, only indicated. The upper mechanical seal 6 separates the cooling circuit from air present in a motor housing 9 of the submersible motor 3, only indicated.

A counter ring 10 is provided axially between the lower mechanical seal 5 and the upper mechanical seal 6. The counter ring 10 is seated on the shaft 2 in a rotationally fixed manner. Both the lower mechanical seal 5 and the upper mechanical seal 6 are in axial contact with the counter ring 10. The counter ring 10 has an impeller 11, shown in 4 as a schematic top view, which serves to circulate the cooling liquid. The ring-like impeller 11 surrounds the counter ring 10 in a radially circumferential manner and is provided in contact with and rotationally fixed to the counter ring 10. A plurality of impeller blades 12 oriented towards the submersible motor 3 are provided on the impeller 11.

The seal cassette 5 has a base body 13 within which the lower mechanical seal 5, the upper mechanical seal 6, the sliding ring 10 and the impeller 11 are arranged. The base body 13 thus radially comprises the mechanical seal 5, the upper mechanical seal 6, the sliding ring 10 and the impeller 11. The base body 13, the lower mechanical seal 5, the upper mechanical seal 6, the sliding ring 10 and/or the impeller 11 are made of metal and/or a plastic, in particular a hard plastic.

In the present case, the base body 13 is designed by three spaced rings 14, which extend around the shaft 2 in the same axis as the lower mechanical seal 5, the upper mechanical seal 6, the sliding ring 10 and the impeller 11. Between the rings 14 are provided with a plurality of spaced-apart, axially extending webs 15. In this way, the base body 13 is designed to be open on its side radially facing away from the lower mechanical seal 5 and the upper mechanical seal 6, so that the cooling liquid can circulate through the openings. A lower ring 14 of the three rings 14 radially surrounds the lower mechanical seal 5, a middle ring 14 radially surrounds the mechanical ring 10 and an upper ring 14 radially surrounds the upper mechanical seal 6. While the upper ring 14 is axially flush with the upper mechanical seal 6, the lower ring 14 is also axially flush with the lower mechanical seal 5 on its radial inner edge, but projects axially beyond the lower mechanical seal 5 on its radial outer edge.

The seal cassette 1 further comprises a lower spring element 16 and an upper spring element 17 for fluid-tight sealing of the lower mechanical seal 5 and the upper mechanical seal 6 with respect to the sliding ring 10 within the base body 13. The lower spring element 16. The lower spring element 16 and the upper spring element 17 each extend axially and are inserted into a respective axial recess of the base body 13 such that a respective axially acting spring force is exerted on a respective collar of the lower mechanical seal 5 and the upper mechanical seal 6 extending radially away from the shaft 2.

Adjacent to the lower spring element 16 and the upper spring element 17, respective circumferentially extending, rectangular in cross-section seals are provided as lower seal 18 and upper seal 19 radially between the respective ring 14 of the base body 13 and the lower mechanical seal 5 and the upper mechanical seal 6. The lower seal 18 and the upper seal 19 are inserted into respective grooves of the lower mechanical seal 5 and the upper mechanical seal 6, which grooves are radially introduced on a side of the lower mechanical seal 5 and the upper mechanical seal 6 facing away from the shaft 2.

For the purpose of a rotationally fixed connection between the base body 13 and the lower mechanical seal 5 and the upper mechanical seal 6, pin-like anti-rotation devices 20 in the form of bolts are provided, which are inserted axially through openings in the radially extending collar into respective axially extending recesses of the corresponding ring 14. The bolts are fixed in place in the recesses, but allow an axial displacement of the lower mechanical seal 5 and the upper mechanical seal 6 relative to the base body 13 or the respective ring 14.

As mentioned at the beginning, the impeller 11 is seated on the shaft 2 in a rotationally fixed manner. For this purpose, two sealing sleeves 21 with a rectangular cross-section are provided on the counter ring 10, which are inserted at a distance from one another on a radial inner side of the counter ring 10 into radial recesses in the counter ring 10 extending away from the shaft 2 and, in this way, contacting both the counter ring 10 and the shaft 2, fix the counter ring 10 or the impeller 11 in a rotationally fixed manner to the shaft 2. The counter ring 10 has a smaller inner diameter than the lower mechanical seal 5 and the upper mechanical seal 6.

Both the upper mechanical seal 6 and the counter ring 10 have an opposite, mutually corresponding axial recess, in detail for the lower mechanical seal 5 in 5 shown, into which an outer support ring 22 is axially shrunk into the upper mechanical seal 6 and, correspondingly, an inner support ring 23 is axially shrunk into the counter ring 10. Likewise, a further opposing, corresponding axial recess is made in the upper mechanical seal 6 and the counter ring 10, into which a further outer support ring 22 and, correspondingly, a further inner support ring 23 are axially shrunk. The respective pair of outer support ring 22 and inner support ring 23 are made of silicon carbide and are in axial contact with one another and in contact with the respective mechanical seal 5, 6 and the counter ring 10.

For the stationary fixing of the impeller 11 to the counter ring 10, a fixing device 24 in the form of a fixing screw extending radially through the counter ring 10 is provided, which is screwed between the sealing sleeves 21 into a thread introduced into the counter ring 10 and fixes the impeller 11 with its tip acting on the latter.

The embodiments described are merely examples that can be modified and/or supplemented in many ways within the scope of the claims. Each feature that has been described for a specific embodiment can be used independently or in combination with other features in any other embodiment. Each feature that has been described for an embodiment of a specific category can also be used in a corresponding manner in an embodiment of another category.

list of reference symbols

1

sealing cassette

2

Wave

3

submersible motor

4

Wave

5

Lower mechanical seal

6

Upper mechanical seal

7

stator

8

heat exchanger flange

9

engine housing

10

counter ring

11

wheel

12

impeller blade

13

base body

14

ring

15

web

16

Lower spring element

17

upper spring element

18

Lower seal

19

upper seal

20

anti-twist device

21

sealing sleeve

22

outer support ring

23

inner support ring

24

fixing device

Claims (13)

Cartridge-like seal cassette (1) for a submersible motor (3) of a pump (4) having an axial shaft (2), comprising a lower mechanical seal (5) designed to separate waste water from a cooling liquid of a cooling circuit of the submersible motor (3) that transports heat from a stator (7) of the submersible motor (3) to a heat exchanger flange (8), an upper mechanical seal (6) designed to separate the cooling circuit from air present in a motor housing (9) of the submersible motor (3), and a counter ring (10) provided axially between the lower mechanical seal (5) and the upper mechanical seal (6) and that can be seated on the shaft (2) in a rotationally fixed manner, wherein the counter ring (10) has an impeller (11) designed to circulate the cooling liquid. Seal cassette (1) according to the preceding claim, with a base body (13), wherein the lower mechanical seal (5), the upper mechanical seal (6) and the counter ring (10) are arranged within the base body (13). Seal cassette (1) according to the preceding claim, with an upper spring element (17) and/or a lower spring element (16), wherein the upper spring element (17) is arranged between the base body (13) and the upper mechanical seal (6) to exert an upper spring force acting in the axial direction on the upper mechanical seal (6) and/or the lower spring element (16) is arranged between the base body (13) and the lower mechanical seal (5) to exert a lower spring force acting in the axial direction on the lower mechanical seal (5). Seal cassette (1) according to one of the two preceding claims, with an upper seal (19) and/or a lower seal (18), wherein the upper seal (19) is arranged radially between the base body (13) and the upper mechanical seal (6) and/or the lower seal (18) is arranged radially between the base body (13) and the lower mechanical seal (5). Sealing cassette (1) according to one of the three preceding claims, with an upper anti-twisting device (20) which is guided axially through the base body (13) and the upper mechanical seal (6), in particular in the form of a pin, and/or a lower anti-twisting device (20) which is guided axially through the base body (13) and the lower mechanical seal (5), in particular in the form of a pin. Seal cassette (1) according to one of the four preceding claims, wherein the base body (13) is designed to be open on its side facing radially away from the upper mechanical seal (6) and/or the lower mechanical seal (5) for the circulation of the cooling liquid. Sealing cassette (1) according to one of the five preceding claims, wherein the base body (13) has at least two rings (14) and webs (15) extending axially between the rings (14) and keeping the rings (14) spaced apart. Sealing cassette (1) according to one of the preceding claims, wherein the counter ring (10) has at least one, in particular two, sealing sleeves (21) which are inserted radially into the counter ring (10) and can be seated on the shaft (2) in a rotationally fixed manner. Seal cassette (1) according to one of the preceding claims, wherein the upper mechanical seal (5) and/or the lower mechanical seal (5) has an outer support ring (22) facing the counter ring (10) and/or the counter ring (10) has an inner support ring (23) facing the upper mechanical seal (6) and/or the lower mechanical seal (5). Sealing cassette (1) according to the preceding claim, wherein the outer support ring (22) and/or the inner support ring (23) is made of silicon carbide. Seal cassette (1) according to one of the two preceding claims, wherein the outer support ring (22) is axially inserted and/or shrunk into the upper mechanical seal (6) and/or the lower mechanical seal (5) and/or the inner support ring (22) is axially inserted and/or shrunk into the counter ring (10). Seal cassette (1) according to one of the preceding claims, with a fixing device (24) extending radially through the counter ring (10) and designed to fix the impeller (11) stationary on the counter ring (10). Submersible motor pump (4), comprising the sealing cassette (1) according to one of the preceding claims, the shaft (2) and the submersible motor (3), wherein the impeller (11) is seated on the shaft (22) in a rotationally fixed manner.

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