Shaft coupling device for a pump

Abstract

Described and claimed is a shaft coupling for attaching a pump drive shaft of a pump assembly to a motor drive shaft of the pump assembly. The shaft coupling comprises a housing for mounting the shaft coupling in a pump housing of the pump assembly. The shaft coupling further comprises a cylindrical coupling sleeve for receiving a drive end of the pump drive shaft and an output end of the motor drive shaft. The coupling sleeve is configured for establishing a rotationally fixed connection between the motor drive shaft and the pump drive shaft. The shaft coupling further comprises a shaft seal circumferentially surrounding the coupling sleeve. The shaft seal prevents pump liquid from leaking out of the pump housing where the coupling sleeve extends through the housing. Further, a pump housing comprising a corresponding shaft coupling and a pump assembly comprising a corresponding pump housing are described and claimed.

Description

Title: SHAFT COUPLING DEVICE FOR A PUMPDescription

[0001] The present invention is directed to a shaft coupling device for a pump housing of a pump assembly, a pump housing of a pump assembly and a pump assembly.

[0002] Centrifugal pump assemblies commonly have a pump housing with one or more impellers and an electric motor for driving the one or more impellers. A drive shaft extends between a rotor of the electric motor and the drive shaft. Many electric motors used for driving smaller pump assemblies are so-called wet-running electric motors where pump fluid is used to lubricate the bearings of the drive shaft and cool the electric motor by flowing through the rotor chamber. The pump fluid flows along the drive shaft out of the pump housing and into the rotor chamber.

[0003] For other and, in particular, larger centrifugal pump assemblies, dry-running electric motors are used. These pump assemblies are also referred to as dry runners. One challenge with dry-running electric motors is that the pump liquid needs to be contained in the pump housing and should not or at least only in controlled amounts leak out of the pump housing where the drive shaft extends through am upper part of the pump housing. Dedicated shaft seals are installed in the pump housing which allow the drive shaft to rotate while at the same time sealing the pump housing.

[0004] Larger pump assemblies are also commonly less integrated than small household centrifugal pumps. This allows using the same type ofelectric motor for a variety of pump assemblies or use different electric motors for each type of pump depending on the application. Also, the electric motors are commonly not installed during production of the pump but attached on-site, i.e., after installation of the pump housing.

[0005] To facilitate the connection of the pump housing and the electric motor, the drive shaft of a pump assembly is split into a pump drive shaft and a motor drive shaft. A drive shaft coupling connects the pump drive shaft and the motor drive shaft. The drive shaft coupling may, for example, be installed between the pump housing and the electric motor. Installing the drive shaft coupling between the pump and electric motor requires a sufficient spacing between the pump housing and the motor housing along a rotational axis of the drive shaft and the impellers.

[0006] An example of an improved shaft coupling device for a pump assembly that is very compact is disclosed in EP 4 198 319 Al . Here, the shaft coupling device is integrated into the rotor of the electric motor so that the electric motor can be placed in relatively close proximity of the pump housing. The drive shaft housing has very small radial dimensions in order to reduced dynamic imbalance. Further, the pump drive shaft and the motor drive shaft can be connected and disconnected without having to disassemble the pump housing or even having to remove the pump drive shaft from the pump housing.

[0007] Against this background, it can be considered an object of the present invention to provide an alternative shaft coupling that allows for an even more compact centrifugal pump assembly. A further object is to provide a pump housing for a compact centrifugal pump assembly and a compact centrifugal pump assembly.

[0008] The object underlying the present invention is solved by a shaft coupling device for an upper part of a pump assembly as wells as pumphousing for a pump assembly and a pump assembly according to the independent claims. Preferred embodiments of the shaft coupling are the subject matter of the dependent claims.

[0009] In a first aspect a shaft coupling device for attaching a pump drive shaft of a pump assembly to a motor drive shaft of a pump assembly is provided. The shaft coupling device comprises a housing for mounting the shaft coupling to an upper part of a pump hosuing, a cylindrical coupling sleeve and a shaft seal circumferentially surrounding the coupling sleeve. The coupling sleeve is configured for receiving a drive end of the pump drive shaft and an output end of the motor drive shaft. The coupling sleeve is further configured for establishing a rotationally fixed connection between the motor drive shaft and the coupling sleeve as well as a rotationally fixed connection between the pump drive shaft and the coupling sleeve so that torque can be transferred from the motor drive shaft via the coupling sleeve to the pump drive shaft. The shaft seal is configured for preventing pump liquid from leaking out of the pump housing where the coupling sleeve assembly extends through the housing.

[0010] In other words, according to the present invention a shaft coupling device is provided which is intended to be installed or mounted in an upper part of a pump housing. The upper part of a pump housing may, for example, be formed by a pump top closing an open end of the pump housing though which, for example, one or more impellers are installed in the pump housing. The pump top maybe a removable cover or lid that is installed on the pump housing after one or more impellers have been placed inside the pump housing.

[0011] The pump housing further comprises a pump inlet through which pump fluid is ingested into the pump housing and a pump outlet through which pump fluid is expelled from the pump housing. The space insidethe pump housing surrounding the one or more impellers may be referred to as an impeller chamber.

[0012] The pump housing is intended to be part of a centrifugal pump assembly. In addition to the pump housing, the pump assembly comprises an electric motor. The electric motor is preferably a dry-running electric motor, for example, a permanent magnet synchronous motor or PMSM. The electric motor drives the one or more impellers located in the pump housing via a drive shaft assembly. The drive shaft assembly connects the rotor of the electric motor to the one or more impellers by extending through the upper part of the pump housing. For preventing pump liquid from leaking at the interface of the pump housing and the drive shaft assembly out of the pump housing, a sealing needs to be provided in the upper part of the pump housing.

[0013] The shaft coupling device comprises three main parts: a housing for attaching the shaft coupling to the pump housing, a coupling sleeve for attaching a pump drive shaft to a motor drive shaft and a shaft seal surrounding the coupling sleeve and preventing pump liquid from leaking along the rotating coupling sleeve out of the pump housing.

[0014] The housing is used for mounting the other parts of the shaft coupling device in the pump housing. The housing thus forms on the one hand the interface of the shaft coupling and the pump housing and on the other hand supports the coupling sleeve and the shaft seal. The housing may also form part of a pump housing closing off part of an opening where the shaft coupling device is installed. Also, the housing may provide additional functions.

[0015] The coupling sleeve is in the present embodiment integrated into the housing and provides a connection between a pump drive shaft and a motor drive shaft. Together the pump drive shaft, the motor drive shaftand the coupling sleeve form the drive shaft assembly that transmits torque from the electric motor to the one or more impellers. Neither the pump drive shaft nor the motor drive shaft protrude all the way through the pump housing but are joined together by the shaft coupling device.

[0016] To this end, the coupling sleeve receives an output end of the motor drive shaft and a drive end of the pump drive shaft when the shaft coupling device is installed in a pump assembly. For a pump assembly that is installed in an upright position, i.e., where a rotational axis of the drive shaft assembly extends vertically, the output end of the motor drive shaft corresponds to a lower end of the motor drive shaft and the drive end of the pump drive shaft corresponds to an upper end of the pump drive shaft. The output end of the motor drive shaft is thus opposite to an end of the motor drive shaft which is attached to the rotor of the electric motor and the drive end of the pump drive shaft is opposite to an end of the pump drive shaft attached to one or more impellers.

[0017] In operation of the pump assembly, the coupling sleeve transmits torque from the motor drive shaft to the pump drive shaft. To this end, the coupling sleeve is configured so that rotationally fixed connections can be established between the coupling sleeve, the output end of the motor shaft and the drive end of the pump drive shaft. The connection between the coupling sleeve and the drive shafts is in other words formed in a manner that prevents a relative rotation about the drive axis between the drive shafts and the coupling sleeve.

[0018] The coupling sleeve provides a torque- bearing connection at the pump housing between the pump drive shaft and the motor drive shaft and thus forms part of the drive shaft assembly. Integrating the shaft coupling device and the shaft seal into one part allows providing a particularly compact pump since no additional coupling device needs to be provided between the pump housing and the motor or in the motor.Also, the connection is simplified os the pump port of the drive shaft assembly and the motor part assembly are kept strictly apart and to their respective domains. Employing an embodiment of a shaft coupling device in the upper part of a pump housing thus advantageously allows completely separating the wet part of the pump assembly from the dry part.

[0019] For preventing pump liquid such as water from leaking out of the pump housing, the shaft coupling comprises a shaft seal. Shaft seals for centrifugal pump assemblies are generally known. They are used for preventing pump liquid from leaking along a rotating pump drive shaft out of the pump housing where the pump drive shaft extends or passes through the stationary upper part of the pump housing, i.e., the cover closing the open end of the pump housing. In the present embodiment the pump drive shaft does not necessarily extend through the pump housing. It is in any case not the radially outermost part of the rotating pump shaft assembly that protrudes out of the pump housing and extends through the pump housing.

[0020] Where the drive shaft assembly extends though the pump housing, the rotating radially outermost part of the pump shaft assembly is formed by the coupling sleeve. Consequently, the shaft seal is not provided for preventing pump liquid from leaking along the pump drive shaft out of the pump housing but from preventing pump liquid from leaking out of the pump housing along the coupling sleeve. Hence, only a single tight sealing device, the shaft coupling device, seals the pump housing. All rotating parts of the pump shaft assembly are in contact with stationary parts of the shaft seal. The remainder of the sealing device is well-known and well-defined. This allows for a particularly tight sealing.

[0021] In a preferred embodiment, an inner surface of the coupling sleeve is formed for establishing a form-fit connection to the drive end ofthe pump drive shaft rotationally fixing the pump drive shaft to the coupling sleeve. Preferably, the form-fit connection does not fix a position of the pump drive shaft in the coupling sleeve in the direction of the rotational axis. In other words, in the preferred embodiment, part of an inner surface of the coupling sleeve is designed for establishing a form-fit or form-locking connection between the coupling sleeve and the pump drive shaft which locks the pump drive shaft and the coupling sleeve against relative axial rotations. However, preferably the form-fit connection does not at the same time fix the relative axial position of the coupling sleeve and the pump drive shaft. The latter enables, for example, inserting the pump drive shaft into the coupling sleeve in a translational movement. It does not exclude that the inner surface of the coupling sleeve limits how far the pump drive shaft can be inserted into the coupling sleeve.

[0022] Preferably, the inner surface of the coupling sleeve comprises a plurality of protruding rips for establishing the form-fit connection rotationally fixing the pump drive shaft to the coupling sleeve. The ribs extend parallel to a rotational axis of the coupling sleeve. The ribs are advantageously provided for engaging corresponding grooves formed at the drive end of the pump drive shaft. Preferably, the rips are equidistantly spaced in a circumferential direction of the sleeve about the rotational axis.

[0023] Hence, in the preferred embodiment means in the form of elongated ribs are provided for forming the positive or form-fit connection transmitting torque from the coupling sleeve to the pump drive shaft. The ribs or elongated protrusions extend along an inner surface of the coupling sleeve facing towards the rotational axis of the drive shaft assembly. The rotational axis is the axis about which the drive shaft assembly rotates during operation of the pump assembly. The ribs are located in a portion of the coupling sleeve where the drive end of the pump driveshaft is received. For example, in case the sealing device is used as part of an upright standing pump assembly where the motor is mounted on top of the pump housing, the ribs could be formed below the upper part of the pump housing or towards the lower or motor-facing or motor-side end of the coupling sleeve.

[0024] A pump drive shaft which is inserted into the coupling sleeve is provided with mating grooves or indentations formed at the drive end of the pump drive shaft. The ribs and the grooves interlock for torque transfer and can provide a connection between the coupling sleeve or coupling device and the pump drive shaft with very little clearance. Also, since the ribs and the grooves are in extended contact along the rotational axis, the pump drive shaft and the coupling sleeve are aligned relative to one another which prevents wear due to misaligned parts of the drive shaft assembly. In an exemplary preferred embodiment, the protruding ribs on the inner surface are only provided for rotationally locking the coupling sleeve to the pump drive shaft.

[0025] In a preferred embodiment, the shaft coupling device further comprises a locking element which is configured to be mounted inside the coupling sleeve and which is further configured for axially fixing the position of the pump drive shaft in the coupling sleeve in the direction of the rotational axis. The locking element is thus an additional part that fixes the relative position of the pump drive shaft and the shaft coupling device in an axial direction.

[0026] Preferably, an outer locking surface of the locking element is formed for a positive lock of the locking element with a corresponding locking section of the inner surface of the coupling sleeve. The positive lock of the locking element with the coupling sleeve secures a position of the locking element in the direction of the rotational axis. Hence, it is preferred that the locking element and the inner surface of the couplingsleeve comprise corresponding or mating locking sections that prevent the locking element from moving relative to the coupling sleeve along or parallel to the rotational axis. The outer locking surface of the locking element is located on a radially outer surface of the locking element that faces away from the rotational axis and towards the inner surface of the coupling sleeve.

[0027] It is further preferred for the outer locking surface of the locking element to comprise one or more circumferentially extending indentations which are configured for engaging one or more protrusions formed on the locking section of the inner surface of the coupling sleeve for forming the form-fit connection of the locking element and the coupling sleeve.

[0028] In other words, in the preferred embodiment at least one and preferably two or more grooves are formed in the outer locking surface of the locking element. The grooves extend annularly in planes that are perpendicular or normal to the rotational axis and are formed in at least a part of the radially outer surface of the locking element. On the inner surface of the coupling sleeve, at least one and preferably two or more corresponding ribs are provided on a part of the coupling sleeve that is referred to as the locking section. The ribs of the locking section also extend in planes that are perpendicular to the rotational axis. In an exemplary preferred embodiment, the relative position of the locking element and the coupling sleeve is only fixed in the direction of the rotational axis, i.e., the locking element can rotate relative to the coupling sleeve when the ribs of the locking section of the coupling sleeve are form-locked with the indentations of the locking element’s outer surface.

[0029] Advantageously, the shaft coupling device comprises both a locking element for fixing the axial position of the pump drive shaft and a plurality of protruding ribs on the inner surface for rotationally lockingthe pump drive shaft to the coupling sleeve. Both means provide a formfit connection but in different directions.

[0030] In another exemplary preferred embodiment, the protruding ribs extending parallel to the rotational axis are arranged between a pumpfacing or pump-side end of the coupling sleeve where the pump drive shaft is inserted into the coupling sleeve and the circumferentially extending ribs on the inner surface of the coupling sleeve that are used for holding the locking element. This embodiment facilitates inserting the pump drive shaft into the coupling sleeve in a translational movement, establishing a rotational lock while inserting the pump drive shaft into the coupling sleeve and afterwards axially fixing or locking the pump drive shaft also in the direction of the rotational axis using the locking element.

[0031] In the latter embodiment, the protruding ribs may also provide an end flange for the locking element that advantageously limits axial movement of the locking element towards the pump-facing end of the coupling sleeve.

[0032] Preferably, the shaft coupling comprises a fastening means for attachment of the locking element to the pump drive shaft. The fastening means is further preferably a threaded bolt which is inserted through the locking element into a bore with a mating thread in the pump drive shaft. Thus, in the preferred embodiment a bolt, screw or other element is used for attaching the locking element to the pump drive shaft. By attaching the pump drive shaft to the locking element, the position of the pump drive shaft is fixed in the direction of the rotational axis in the coupling sleeve.

[0033] In a further preferred embodiment, the locking element is configured so that by tightening the fastening means, the outer locking surfaceof the locking element is moved towards the locking section of inner surface of the coupling element. In other words, in the preferred embodiment tightening the fastening means by, for example, turning the bolt further into the bore in the pump drive shaft, firmly attaches the pump drive shaft to the locking element and furthermore improves the form-fit between the locking element and the coupling sleeve.

[0034] In a preferred embodiment the locking element comprises an open end facing towards a pump-facing end of the coupling sleeve when the locking element is mounted in the coupling sleeve. The locking element comprises two or more slots extending in parallel to the rotational axis. The two or more slots extend away from the open end. At least one of the open end of the locking element facing towards the pump-facing end of the coupling sleeve or the drive end of the pump drive shaft are at least partially conically shaped and configured so that by tightening the fastening means, the drive end of the pump drive shaft is pulled into the open end of the locking element whereby the outer locking surface of the locking element is pushed towards the locking section of the coupling sleeve.

[0035] In other words, in the preferred embodiment the radial extension of the locking element can be increased by pulling a tip of the pump drive shaft into a cavity formed by the locking element. At least one of the tip or drive end of the pump drive shaft and the inner surface of the locking element facing towards the pump drive shaft are partially conically shaped, for example, frusto-conically shaped. Further, the locking element comprises at least two and preferably four slots extending away from the end of the locking element facing towards the pump drive shaft.

[0036] When the pump drive shaft is pulled into locking element, for example, by tightening the screw forming the fastening means, an at leastpartially conical outersurface on the tip of the pump drive shaft engages with a preferably mating inner surface on the locking element. The slots in the locking element allow the locking element to widen in the radial direction, i.e., in planes extending normal to the rotational axis and thereby push the indentations formed on the outer locking surface of the locking element further into the ribs formed on the locking section of the coupling sleeve. Thereby, the axial form-fit between the locking element and the coupling sleeve is improved.

[0037] In an exemplary preferred embodiment, the shaft coupling device comprises a locking element and the plurality of protruding ribs on the inner surface providing torque transfer to the drive end of the pump drive shaft. In this embodiment, the protruding ribs advantageously prevent a rotation of the pump drive shaft when the fastening means is tightened which simplifies securing the pump drive shaft to the coupling sleeve. Thus, a combined effect of the separate structural features is achieved.

[0038] In a preferred embodiment, the shaft coupling device further comprises a rotor clamp surrounding the coupling sleeve, wherein the rotor clamp is configured for fixing or securing the motor drive shaft in the coupling sleeve. The rotor clamp arranged on the outside of the coupling sleeve is provided for locking the motor drive shaft in the coupling sleeve. Since the rotor clamp is located outside of the coupling sleeve, it can be easily accessed even after the motor has been installed on the pump housing.

[0039] In a further preferred embodiment, a rotor clamp is attached to the coupling sleeve adjacent to a motor-facing end of the coupling sleeve through which the motor drive shaft is received in the coupling sleeve. One or more slots extending away from the motor-facing end are formed in the coupling sleeve. The rotor clamp is configured so that bytightening the rotor clomp, a diameter of the coupling sleeve is reduced for securing the motor drive shaft in the coupling sleeve. The rotor clamp rotates with the coupling sleeve during operation of the pump assembly.

[0040] In other words, the rotor clamp is preferably provided for squeezing the coupling sleeve towards the motor drive shaft after the motor drive shaft has been inserted in the coupling sleeve. The rotor clamp is arranged adjacent to the motor-facing end of the coupling sleeve and, in particular, outside of the pump housing when the shaft coupling device has been mounted to a pump housing, i.e., it is arranged on the side of the housing facing away from the pump housing so that it can be accessed after the shaft coupling device has been installed in a pump housing.

[0041] The rotor clamp may, for example, comprise two parts which can be tightened using one or more bolts. Preferably, two bolts are used for tightening a rotor clamp with two parts for distributing the forces required for securing the motor drive shaft. After insertion of the motor drive shaft into the coupling sleeve, the rotor clamp is placed around the coupling sleeve and tightened. Thereby, the diameter of the coupling sleeve is reduced, and the motor drive shaft is tightly locked in place.

[0042] To facilitate locking of the motor drive shaft in place, two or more slots or gaps are provided in the coupling sleeve. The slots start at the motor-facing end of the coupling sleeve and extend at least to a part of the coupling sleeve where the rotor clamp is placed. Preferably, the slots extend up to the housing or at most up to the shaft seal so that the slots do not impact the sealing effect of the soft seal. The slots allow for an easier deformation of the coupling sleeve so that the motor drive shaft can be held securely in place.

[0043] In a preferred embodiment, the coupling sleeve comprises on an outer surface a circumferential protrusion for axially fixing the rotor clamp in the direction of the rotational axis on the coupling sleeve. The circumferential protrusion deviates preferably in one or more sections from a circular shape for enabling a rotationally fixed connection between the coupling sleeve and the rotor clamp. In other words, an annular protrusion or rib is formed on an outer surface of the coupling sleeve which defines the axial position of the rotor clamp along the rotational axis. The rotor clamp has a mating indentation in an inners surface which is in extended contact with the outer surface of the coupling sleeve after the rotor clamp has been mounted. Alternatively, the rib may be located on the inner surface of the rotor clamp and the indentation may be formed in the outer surface of the coupling sleeve.Further preferably, the rib and the groove are not of equal height and depth for their entire extension. Rather, it is contemplated that at least partially the height of the rib varies and so does the depth of the groove. In other words, the rib and the groove do not follow a circle about the rotational axis. By deviating from a circular shape, the rib and groove can be also used to rotationally lock the relative orientation of the rotor clamp and the coupling sleeve.

[0044] Furthermore, in a preferred embodiment an outer surface of the coupling sleeve comprises adjacent to a pump-facing end of the coupling sleeve an indentation for receiving a mounting means, wherein the mounting means extends circumferentially about the coupling sleeve and supports a ring-shaped bracket. The mounting means or positioning element may be a spring ring that is located inside the pump housing after the shaft coupling device has been installed. It supports a ringshaped bracket which may, for example, hold a spring that is part of the shaft seal under tension.

[0045] In a second aspect, a pump housing for a pump assembly comprising at least one impeller rotatably driven by a pump drive shaft is provided. The pump housing comprises a shaft coupling according to any of the preceding embodiments arranged at an upper part of the pump housing. The pump drive shaft is connected to the coupling sleeve of the shaft coupling device. The advantages of the pump housing correspond to the advantages of the shaft coupling device integrated into the upper part of the pump housing.

[0046] In a third aspect, a pump assembly comprising a pump housing according to any of the preceding embodiments and an electric motor driving a motor drive shaft are provided. The motor drive shaft is connected via the coupling sleeve to the pump drive shaft to form a drive shaft assembly.

[0047] Advantageously, a particularly compact drive shaft assembly can be provided as the shaft coupling device connecting the pump drive shaft and the motor drive shaft is integrated into the shaft seal and, thus, the pump top of the pump housing. Further advantages of the pump assembly have already been described with reference to the preferred embodiments of a shaft coupling device.

[0048] In the following, an exemplary embodiment of a sealing device, and an exemplary embodiment of a pump housing will be described with reference to the drawings, whereinFigure 1 shows a sectional view of an exemplary embodiment of a shaft coupling device in a partially exploded view,Figure 2 shows a sectional view of the embodiment of Figure 1 with a pump drive shaft inserted into a coupling sleeve,Figure 3 shows a sectional with of the embodiment of Figures 1 and 2 with a pump drive shaft secured using a locking element and a fastening means in the coupling sleeve,Figure 4 shows a sectional view of the coupling sleeve including the pump drive shaft, the locking element, and the fastening means of Figure 3,Figure 5 shows a perspective view of the exemplary embodiment of the shaft coupling device of Figure 1 ,Figure 6 shows an exemplary embodiment of a pump housing with an exemplary embodiment of a shaft coupling device to be attached to the pump housing,Figure 7 shows a partially sectional view of the exemplary embodiment of a pump housing of Figure 6 with the exemplary embodiment of the shaft coupling device attached to the pump housing, andFigure 8 shows an exemplary embodiment of a pump assembly comprising a motor and a pump housing.

[0049] Figures 1 to 5 show an exemplary embodiment of a shaft coupling device 1 and parts thereof in different configurations. Identical reference numerals have been used throughout the Figures. However, not every part has been designated in every Figure with a reference numeral to keep the Figures intelligible.

[0050] The main parts of the shaft coupling device 1 are a housing 3, a shaft seal 5 and a coupling sleeve 7. The housing 3 is provided for mounting the shaft coupling device 1 in an upper part of a pump housing (not shown in figures 1 to 5). For integrating the shaft coupling device 1 into the pump housing, a circumferential seal 9 is provided. The seal 9 is formed by an O-ring that is located in a groove 1 1 where the housing 3 is in immediate circumferential contact with the pump housing.

[0051] The housing 3 further comprises a sensor 13 for determining whether air has accumulated at the shaft coupling device 1 . Since the shaft seal 5 is lubricated by pump liquid, it is essential for the pump housing (not shown) to be completely filled with pump liquid. Otherwise, the shaft seal 5 would be subject to excessive wear.

[0052] Furthermore, a venting arrangement 15 is provided for releasing air trapped at the top of the housing 3. Both the sensor 13 and the venting arrangement 15 are provided in a part of the housing 3 projecting over the upper part of the pump housing and are located outside of the pump housing when the shaft coupling device 1 is installed in a pump housing.

[0053] The center of the shaft coupling device 1 is formed by the elongated coupling sleeve 7. The coupling sleeves connects a pump drive shaft 19 of a pump assembly to a motor drive shaft of a motor of the pump assembly. The motor and the motor drive shaft are not shown in the Figures. Note that the pump drive shaft 1 which is partially shown in Figures 1 to 4 is not part of the shaft coupling device 1 .

[0054] The coupling sleeve 7 forms together with the pump drive shaft 19 and the motor drive shaft a drive shaft assembly 21. The drive shaft assembly 21 transfers torque generated by the rotor of an electric motor via the motor drive shaft, the coupling sleeve 7 and the pump drive shaft 19 to one or more impellers of the pump assembly. The drive shaft assembly 21 and its parts are, therefore, together rotating about a rotational axis 23. The elongated coupling sleeve 7 extends along the rotational axis 23.

[0055] The coupling sleeve 7 is provided for a transferring torque from the motor drive shaft to the pump drive shaft 19. To this end it comprises means for connecting the coupling sleeve 7 to both drive shafts 19 in away that ensures that the coupling sleeve 7 and the drive shafts 19 are rotationally locked or rotationally fixed. A connection is rotationally locked or locked when under regular operating conditions there is no relative rotational movement about the rotational axis 23 between connected parts.

[0056] For establishing a rotationally locked connection between the pump drive shaft 1 and the coupling sleeve 7, a plurality of elongated ribs 25 are formed on an inner surface 27 of the coupling sleeve 7. The inner surface 27 of the coupling sleeve 7 is the surface 27 of the coupling sleeve 7 facing towards the rotational axis 23.

[0057] The equidistant ribs 25 are formed for engaging corresponding grooves 29 formed at a drive end 31 of the pump drive shaft 19. In a circumferential direction about the rotational axis 23, the grooves 29 are formed as matching counterparts of the ribs 25. However, along the rotational axis 23 the grooves 29 are longer than the ribs 25. This facilitates insertion of the pump drive shaft 19 into the coupling sleeve 7. Further, the positive lock of the ribs 25 and the grooves 29 aligns the pump drive shaft 19 and the coupling sleeve 7 along the rotational axis 23 due to the extended contact between the connected parts. In case the coupling sleeve 7 and the pump drive shaft 19 would not be aligned, excessive wear would be caused.

[0058] For securing the pump drive shaft 19 in the direction of the rotational axis 23, a locking element 33 is provided which is installed inside the coupling sleeve 7. The locking element 33 comprises a plurality of indentations 35 on an outer surface 37. The indentations 35 are only formed in a part of the outer surface 37 which is also referred to as the outer locking surface 39 of the locking element 33. The indentations 35 extend annularly about the rotational axis 23 and are formed in planes that are normal to the rotational axis 23.

[0059] On the inner surface 27 of the coupling sleeve 1 , correspondingly shaped circumferential ribs 41 are provided. The circumferential ribs 41 also extend in planes that are normal to the rotational axis 23, i.e., the ribs 41 extend perpendicular to the ribs 25 that are provided for establishing a rotational lock between the coupling sleeve 7 and the pump drive shaft 19. Different numbers of circumferential ribs 41 and circumferential indentations 35 may be provided. The part of the inner surface 27 of the coupling sleeve 7 where the circumferential ribs 41 are formed may also be referred to as a locking section 42 of the coupling sleeve 7.

[0060] The circumferential ribs 41 and the circumferential indentations 35 on the locking element 33 engage when the locking element 33 is installed in the coupling sleeve 7. For facilitation insertion into the coupling sleeve, the locking element 33 comprises a plurality of slots 43 that allow compressing or widening the locking element 33 radially, i.e., in directions extending perpendicular to the rotational axis 23. When the locking element 33 has been installed in the coupling sleeve 7, the ribs 41 and the indentations 35 provide a form-fit connection fixing the locking element 33 in the direction of the rotational axis 23.

[0061] For positioning the pump drive shaft 19 along the rotational axis 23 in the coupling sleeve 7, an additional threaded bolt 45 or screw 45 is used. The screw 45 is inserted through the hollow locking element 33 until a head 49 of the bolt 45 contacts a circumferential collar 47 inside the locking element 33 via an intermediate disc 48 which prevents twisting of the locking element 33. The threaded bolt 45 can also be referred to as a fastening means 45. The collar 47 thus limits how far the bolt 45 can be inserted into the locking element 33.

[0062] The pump drive shaft 19 comprises at its drive end 31 a threaded bore 51 for receiving the bolt 45. By screwing the bolt 45 into the bore 51 in the top of the pump drive shaft 19, the pump drive shaft 19 is positionedalong the rotational axis 23. Since the axial ribs 25 on the inner surface 27 of the coupling sleeve engage axial grooves 29 on the pump drive shaft 1 , the pump drive shaft 19 cannot rotate relative to the coupling sleeve 7 when the bolt 45 is tightened. The coupling sleeve 7 and the pump drive shaft 19 are rotationally locked. The position of the pump drive shaft 19 inside the coupling sleeve in the direction of the rotational axis is thus defined by the position of the locking element 33.

[0063] For further securing the pump drive shaft 19 in the coupling sleeve 7 and improving the form-fit between the locking element 33 and the coupling sleeve 7, the drive end 31 of the coupling sleeve 7 has at least partially a conical or frusto-conical shape in an insertion section 53. The locking element 33 has a corresponding open end 55 which is also conically shaped. Note that the slots 43 provided in the locking element 33 extend away from the open end 55.

[0064] When the bolt 45 is tightened, the insertion section 53 of the pump drive shaft 19 is pulled into the open end 55 of the locking element 33 and pushes the locking section 39 of the locking element 33 further towards the locking section 42 of the coupling sleeve 7. Thus, by tightening the connection between the locking element 33 and the pump drive shaft 19, the form-fit connection between the locking element 33 and the coupling sleeve 7 is improved.

[0065] The pump drive shaft 19 comprises below the grooves 29, i.e., on the side of the grooves 29 facing away from the drive end 31 a circumferential indentation 57 in which a seal 59 in form of an O-ring is placed. The seal 59 is in contact with the inner surface 27 of the coupling sleeve 7 when the pump drive shaft 19 has been secured in the coupling sleeve 7 and prevents pump liquid from leaking along the pump drive shaft 19 into the coupling sleeve 7. Since the coupling sleeve 7 and the pumpdrive shaft 19 are rotationally locked, a conventional rubber seal 59 can be used.

[0066] For connecting a motor drive shaft to the coupling sleeve 7, a rotor clamp 61 is provided. As can be seen best in figure 5, the rotor clamp 61 comprises two parts which are attached to each other using threaded bolts 63. The rotor clamp 61 is attached at a motor-facing or motor-side end 65 of the coupling sleeve 7. The opposing end 66 may also be referred to as a pump-facing or pump-side end 66 of the coupling sleeve 7.

[0067] As can further be seen best in figure 5 but is also visible in figures 1 to 4, the coupling sleeve 7 comprises two slots or gaps that extend from the motor-side end 65 of the coupling sleeve 7 along the rotational axis 23. The slots 67 extend along the rotational axis 23 until about where a head 69 of the locking element 33 is positioned when the locking element 33 has been installed inside the coupling sleeve 7 as can be seen in figures 3 and 4 which corresponds to the upper end of the shaft seal 5. Once an output end of a motor drive shaft has been inserted into the coupling sleeve 7, the bolts 63 of the rotor clamp 61 are tightened and the coupling sleeve 7 is compressed where the rotor clamp 61 has been placed. By tightening the bolts 64, the coupling sleeve 7 can, therefore, be secured to an output end of a motor drive shaft.

[0068] The rotor clamp 61 rotates with the coupling sleeve 7 during operation of a pump assembly. To secure both the axial location to the rotor clamp 61 as well as rotationally locking it to the coupling sleeve 7, a circumferential protrusion 71 is formed towards the motor-side end 65 of the coupling sleeve 7. The protrusion 71 engages with a corresponding indentation 73 formed in the rotor clamp 61 . Thereby, the axial location of the rotor clamp 61 along the rotational axis 23 is secured.

[0069] Further, the angular or circumferential protrusion 71 is not circular but has two flattened sections 75. One of these flattened sections 75 is depicted in figure 5. The indentations 73 in the rotor clamp 61 have corresponding flattened sections 77. The combination of the flattened sections 75, 77 that constitute deviations from a circular shape fixes the rotational position of the rotor clamp 61 relative to the coupling sleeve 7.

[0070] The coupling sleeve 7 further comprises an annular collar 79 on its outer surface 81 . The collar49 is provided for stripping off any pump liquid that is able to flow past the shaft seal 5 and ensure that it does not continue flowing towards the motor. Drops of pump liquid are collected at the annular collar 79 and stripped-off at the outer edge of the annular collar 79.

[0071] A further groove 83 is formed in the outer surface 81 of the coupling sleeve 7 towards the pump-side end 66 of the coupling sleeve 7. A mounting means 85 is placed in this indentation 83. The mounting means 85 is in the exemplary embodiment shown in the figures 1 to 5 a spring ring which supports a bracket 87. The bracket 87 holds a spring 89 of the shaft seal 5 under tension.

[0072] In operation of the pump assembly, the bracket 87 rotates with the coupling sleeve 7 and limits the extension of the spring 89 which holds a rubber sealing element 91 of the shaft seal 5 in place. The sealing element 91 is in extended axial contact with the coupling sleeve 7 and provides an axial seal that prevents pump liquid from leaking out of the pump housing. Further details of the shaft seal 5 are not discussed here as they are well-established in the art.Finally, Figures 6 and 7 show an exemplary embodiment of a pump housing 95 with a shaft coupling device 1 . In Figure 6 the shaft coupling device 1 is shown separate from the pump housing 95 whereas in Figure 7that shaft coupling has been installed in an upper part 97 of the pump housing 95. The shaft coupling device 1 corresponds to the shaft coupling device 1 discussed with reference to Figures 1 to 5. Therefore, reference is made to the previous description of the shaft coupling device 1 .The pump housing 95 comprises a pump inlet 99 and a pump outlet 101 which are in fluid connection with an impeller chamber 103 housing one or more impellers 105. The pump housing 95 may be used for a single- stage pump with one impeller or a multi-stage pump with multiple impellers. In Figures 6 and 7 it is used for a centrifugal pump with two stages. As can be seen in Figure 7, the impeller 105 is connected to the pump drive shaft 19.Figure 6 shows the pump housing 95 and the shaft coupling device 1 as separate parts. The upper part 97 of the pump housing comprises an opening 107 in its center where the shaft coupling device 1 will installed. The shaft coupling device 1 is secured with four mounting bolts 109 to the pump housing 95. As can be seen particularly well from Figure 6, the present invention separates the interior of the wet-running pump housing 95 entirely from the motor. All wet parts of the pump including the pump drive shaft 19 are installed in the pump housing 95 before the latter is sealed off using the shaft coupling device 1 . The mounting bolts 109 are inserted through holes 1 10 in the housing 3 of the shaft coupling device 1 and secured in corresponding threaded bores 1 12 in the upper part 97 of the pump housing 95.Figures 6 and 7 highlight one of the key advantages of the shaft coupling device 1 disclosed herein. The pump housing 95 can be completed and sealed with the shaft coupling device 1 installed therein. For attaching or detaching an electric motor from the pump housing 95, it is not necessary to open the pump housing or even remove the pump drive shaft 19. The connection can be established and released by closing or opening,respectively, the rotor clomp 61 on top of the upper port 97 of the pump housing 95.Finally, Figure 8 shows an exemplary embodiment of a pump assembly 1 1 1 comprising a pump housing 95 and a motor 1 13. The motor 1 13 is located in a motor housing 1 15 that has been mounted on the uprightstanding pump housing 95 using a motor stool 1 17. A motor drive shaft 1 19 protrudes out of a lower end of the motor 1 13 and is joined using a shaft coupling device 1 to the pump drive shaft (now shown) located inside the pump housing 95. The pump housing 95 and the shaft coupling device 1 of the exemplary embodiment shown in Figure 8 correspond to the exemplary embodiments discussed with regard to Figures 1 to 7.The pump assembly 1 1 1 shown in Figure 8 is particularly compact due to the integration of the shaft coupling device 1 into the upper part 97 of the pump housing 95. Furthermore, it can be seen in Figure 8 that due to the location of the rotor claim 61 on top of the pump housing 95, the motor 1 13 can be attached to the pump housing 95 and detached from the pump housing 95 without having to open either of the pump housing 95 or the motor housing 1 15. This makes for a simple installation and maintenance of the pump assembly 1 1 1. Also, the inside of the pump housing 95 and the motor housing 1 15 are protected from dirt.List of reference numeralsI shaft coupling device3 housing5 shaft seal7 coupling sleeve9 seal, O-ringI I groove13 sensor15 venting arrangement19 pump drive shaft21 drive shaft assembly23 rotational axis25 ribs27 inner surface of the coupling sleeve29 grooves31 drive end33 locking element35 indentations on locking element37 outer surface of locking element39 locking section of locking element41 ribs42 locking section of the coupling sleeve43 slots45 bolt47 collar48 disc49 head of bolt51 bore53 insertion section55 open end57 indentation59 seal61 rotor clamp63 threaded bolts65 motor-facing end66 pump-facing end67 axial slot, gap69 head of locking element71 protrusion73 indentation75 flattened section77 flattened section79 collar81 outer surface of coupling sleeve83 indentation85 mounting means, spring ring87 bracket89 spring91 sealing element95 pump housing 97 upper part of the pump housing99 pump inlet101 pump outlet103 impeller chamber105 impeller 107 opening109 mounting bolts1 1 1 pump assembly1 13 motor1 15 motor housing 1 17 motor stool1 19 motor drive shaft

Claims

Claims1 . A shaft coupling device ( 1 ) for attaching a pump drive shaft (19) of a pump assembly (1 1 1 ) to a motor drive shaft (1 1 ) of the pump assembly (1 1 1 ), wherein the shaft coupling device ( 1 ) comprises a housing (3) for mounting the shaft coupling device ( 1 ) in an upper part (97) of a pump housing (95) of the pump assembly (1 1 1 ), a cylindrical coupling sleeve (7) for receiving a drive end (31 ) of the pump drive shaft (19) and an output end of the motor drive shaft (1 19), wherein the coupling sleeve (7) is configured for establishing a rotationally fixed connection between the motor drive shaft (1 19) and the coupling sleeve (7) as well as a rotationally fixed connection between the pump drive shaft (19) and the coupling sleeve (7) so that torque can be transferred from the motor drive shaft (1 19) via the coupling sleeve (7) to the pump drive shaft ( 19), and a shaft seal (5) circumferentially surrounding the coupling sleeve (7), wherein the shaft seal (5) is configured for preventing pump liquid from leaking out of the pump housing (95) where the coupling sleeve (7) extends through the housing (3).

2. Shaft coupling device (1 ) according to claim 1 , wherein an inner surface (27) of the coupling sleeve (7) is formed for establishing a form-fit connection to the drive end (31 ) of the pump drive shaft (19) rotationally fixing the pump drive shaft (19) to the coupling sleeve (7).

3. Shaft coupling device (1 ) according to claim 2, wherein the inner surface (27) of the coupling sleeve (7) comprises a plurality of protruding rips (25) for establishing the form-fit connection rotationally fixing the pump drive shaft (19) to the coupling sleeve (7), whereinthe ribs (25) extend parallel to a rotational axis (23) of the coupling sleeve (7).

4. Shaft coupling device ( 1 ) according to claim 1 , 2, or 3, wherein the shaft coupling device (1 ) further comprises a locking element (33) which is configured to be mounted inside the coupling sleeve (7) and which is further configured for axially fixing the position of the pump drive shaft (19) in the coupling sleeve (7) in the direction of the rotational axis (23).

5. Shaft coupling device (1 ) according to claim 4, wherein an outer locking surface (39) of the locking element (33) is configured for a form-fit connection with a corresponding locking section (42) of the inner surface (27) of the coupling sleeve (7), wherein the form-fit connection of the locking element (33) with the coupling sleeve (7) axially fixes the position of the locking element (33) in the direction of the rotational axis (23).

6. Shaft coupling device (1 ) according to claim 5, wherein the outer locking surface (39) of the locking element (33) comprises one or more circumferentially extending indentations (35) which are configured for engaging one or more protrusions (41 ) formed on the locking section (42) of the inner surface (27) of the coupling sleeve (7) for forming the form-fit connection of the locking element (33) and the coupling sleeve (7).

7. Shaft coupling device (1 ) according to any of claims 4, 5, or 6, wherein the shaft coupling device ( 1 ) comprises a fastening means (45) for attaching the locking element (33) to the pump drive shaftwherein the fastening means (45) is preferably a threaded bolt (45) which is inserted through the locking element (33) into a bore (51 ) with a mating thread in the pump drive shaft (19).

8. Shaft coupling device (1 ) according to any of claims 5 or 6 and claim 7, wherein the locking element (33) is further configured so that by tightening the fastening means (45), the outer locking surface (39) of the locking element (33) is moved towards the locking section (42) of the inner surface (27) of the coupling sleeve (7).

9. Shaft coupling device ( 1 ) according to claim 8, wherein the locking element (33) comprises an open end (55) facing towards a pumpfacing end (66) of the coupling sleeve (7) when the locking element (33) is mounted in the coupling sleeve (7), wherein the locking element (33) comprises two or more slots (43) extending parallel to the rotational axis (23) and away from the open end (55), and wherein at least one of the open end (55) of the locking element (33) facing towards the pump-facing end (66) of the coupling sleeve (7) or the drive end (31 ) of the pump drive shaft ( 19) are at least partially conically shaped and configured so that by tightening the fastening means (45), the drive end (31 ) of the pump drive shaft (19) is pulled into the open end (55) of the locking element (33) whereby the outer locking surface (39) of the locking element (33) is pushed towards the locking section (42) of the coupling sleeve (7).

10. Shaft coupling device (1 ) according to any of the preceding claims, wherein the shaft coupling device (1 ) further comprises a rotor clamp (61 ) surrounding the coupling sleeve (7), wherein the rotor clamp (61 ) is configured for fixing the motor drive shaft in the coupling sleeve (7).1 1 . Shaft coupling device ( 1 ) according to claim 10, wherein the rotor clamp (61 ) is attached to the coupling sleeve (7) adjacent to a mo- tor-facing end (65) of the coupling sleeve (7) through which the motor drive shaft (1 19) is received in the coupling sleeve (7), wherein the coupling sleeve (7) comprises one or more slots (67) extending away from the motor-facing end (65) of the coupling sleeve (7), and wherein the rotor clamp (61 ) is configured so that by tightening the rotor clamp (61 ), a diameter of the coupling sleeve (7) is reduced for fixing the motor drive shaft (1 1 ) in the coupling sleeve (7).

12. Shaft coupling device ( 1 ) according to claim 10 or 1 1 , wherein the coupling sleeve (7) comprises on an outer surface (81 ) a circumferential protrusion (71 ) for axially fixing a position of the rotor clamp (61 ) in the direction of the rotational axis (23) on the coupling sleeve (7), wherein the circumferential protrusion (71 ) deviates preferably in one or more sections from a circular shape for enabling a rotationally fixed connection between the coupling sleeve (7) and the rotor clamp (61 ).

13. Shaft coupling device (1 ) according to any of the preceding claims, wherein an outer surface (81 ) of the coupling sleeve (7) comprises adjacent to the pump-facing end (66) of the coupling sleeve (7) an indentation (83) for receiving a mounting means (85), wherein the mounting means (85) extends circumferentially about the coupling sleeve (7) and supports a ring-shaped bracket (87).

14. A pump housing (95) for a pump assembly comprising at least one impeller (105) rotatably driven by a pump drive shaft (19), whereinthe pump housing (95) comprises a shaft coupling device (1 ) according to any of the preceding claims arranged in an upper part (97) of the pump housing (95) and wherein the pump drive shaft (19) is connected to the coupling sleeve (7) of the shaft coupling device (1 ).

15. A pump assembly (1 1 1 ) comprising a pump housing (95) according to claim 14 and an electric motor (1 13) driving a motor drive shaft (1 19), wherein the motor drive shaft ( 1 19) is connected via the coupling sleeve (7) to the pump drive shaft (1 ).

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