Modular System of an Axially Integrated Pump Structure
A modular system for a pump structure for the axial integration of a selection of electric drive assemblies (1) at a selection of pump assemblies (2) and a shaft bearing assembly (3) which includes a pump shaft (31) and a shaft bearing (32) with at least two rolling bearing sets, the shaft bearing (32) supporting the pump shaft (31) between a motor rotor (1) of the electric drive assembly (1) and a pump rotor (21) of the pump assembly (2) at a pump housing (20) of the pump assembly (2); wherein the selection of pump assemblies (2) jointly comprises a collar portion (23) at the pump housing (20) which accommodates the shaft bearing (32) in a through-hole of the pump housing (20) and protrudes to an accommodation side for an electric drive unit (1); and the selection of pump assemblies (2) differs with respect to the pump rotor (21) and/or a pump chamber (22); the selection of drive assemblies (1) jointly comprises a motor rotor (11) which is formed at a radially external section in the shape of a rotor cup (13), the rotor cup (13) radially encircling and axially intersecting the collar portion (23) that each pump housing (20) of the selection of drive assemblies (1) jointly comprises; and the selection of drive assemblies (1) differs with respect to a stator (12); and wherein for each combination of the selection of electric drive assemblies (1) and the selection of pump assemblies (2), at least one radial dimension of the pump shaft, the shaft bearing, the collar portion (23) and/or the rotor cup (13) are the same.
The present invention relates to a modular system for a compact pump structure for the axial integration of an electric drive assembly at a pump assembly including a common shaft bearing.
An advantageous pump structure with a compact axial dimension is known e.g. from patent application DE 10 2016 119 985 A1, which was not yet laid-open on the application date of this patent application, by the same applicant which describes a rotary piston vacuum pump. Said pump structure integrates the electric drive in a small installation space with the other components of the pump and has only a single shaft bearing with two ball bearing raceways. In comparison with a pump structure comprising two shaft bearings and an axially adjacent arrangement of the drive and pump, such a pump structure offers a reduction in axial length and offers an advantageous basis for a pump structure of different pumps with a compact configuration and a small axial dimension. Furthermore, it is not necessary to take into consideration any centring tolerance between the bearing seats in the bearing clearances and assembly outlay with centring is not required for the second shaft bearing. A reduced bearing clearance results in less tilting of the shaft and thus in less wear of the shaft bearing.
Conventionally, in the case of the design of a pump structure, the pump type and the use are initially determined, according to which a dimensioning of components, such as a shaft bearing and a shaft seal, is determined on the basis of the forces and pressures occurring according to use. One form of the pump housing is designed individually ultimately for the relative fixing and bearing of the assemblies around the selected components.
This gives rise to the circumstance that, in order to produce a product range of different pumps which differ in terms of pump type, volumetric design or drive capacity, said approach requires for each pump an individual pump structure having a large number of different components, in particular moulded parts, which always vary in dependence upon a type of assembly or the parameters thereof. As a consequence, the production of a product range consisting of different pumps is associated with considerable expense for providing a large selection of mould tools for casting housing parts or for acquiring and stock holding the numerous components and individual parts. Furthermore, different pump structures amongst the products involve individual assembly sequences during manufacture. Accordingly, there is room for cost-reducing simplifications in the production and assembly of different pumps from a product range.
It is an object of the invention to select common and different design features between assemblies, which permits standardisation of the pump structure without impairing utilisation of the installation space. In the latter condition, the objective is particularly that of avoiding a deterioration in a compact configuration, as would exist e.g. by providing a large universal installation space in the pump housing which is used inefficiently in different embodiments.
This object is achieved in accordance with the invention by a modular system for a pump structure comprising the features of claim 1. The modular system for a pump structure for the axial integration of an electric drive assembly at a pump assembly includes: a selection of electric drive assemblies with different drive capacities; a selection of pump assemblies with different volumetric capacities and/or different configurations; and a shaft-bearing-assembly including a pump shaft and a shaft bearing with at least two rolling bearing sets, the shaft bearing supporting the pump shaft between a motor rotor of the electric drive assembly and a pump rotor of the pump assembly at a pump housing of the pump assembly; the selection of pump assemblies jointly comprises a collar portion at the pump housing which accommodates the shaft bearing in a through-hole of the pump housing and protrudes to an accommodation side for an electric drive unit; and the selection of pump assemblies differs with respect to the pump rotor and/or a pump chamber; the selection of drive assemblies jointly comprises a motor rotor which is formed at a radially external section in the shape of a rotor cup, the rotor cup radially encircling and axially intersecting the collar portion that each pump housing of the selection of drive assemblies jointly comprises; and the selection of drive assemblies differs with respect to a stator; and wherein for each combination of the selection of electric drive assemblies and the selection of pump assemblies, at least one radial dimension of the pump shaft, the shaft bearing, the collar portion and/or the rotor cup are the same.
Therefore, the invention firstly provides a modular system which defines an axial intersection of the assemblies as a spatial interface between selection combinations amongst the assemblies in order to permit design standardisation of the pump structure or the use of identical components. The modular system permits a universal integration of an individual combination of assemblies out of a selection of assemblies in a compact pump structure. The standardisation of components and a relative arrangement thereof with respect to one another provides, in the manufacture of pumps, cost advantages by reason of a reduction in the production of different moulded parts and a reduction in different procedures and tools during the assembly of the pumps.
By virtue of the inventive specification of identical features and distinguishing features or parameters within a selection of the respective assemblies, a spatial interface for standard components is firstly selected between three assemblies in a pump structure. This structural interface defines at the same time an axial intersection of the assemblies, whereby an integrated compact pump structure is achieved for each combination of assemblies.
For example, by reason of a width of the stator of the electric drive a drive capacity can be increased by means of larger field coils, whereas all other components including the rotor cup remain the same. Likewise, a size of the pump rotor and the pump chamber can vary, whereas all other components and assemblies of the pump structure remain the same. Furthermore, a pump assembly of another pump type can be connected to the same pump shaft, whereas all other components and assemblies of the pump structure remain the same.
Adopting a common radial dimension within the spatial interface ensures not only that the assemblies can be integrated in an axial intersection but also that identical components or components with identical dimensions, such as e.g. an identical shaft bearing and a pump shaft consisting of a blank with an identical diameter, can be used.
According to one aspect of the invention, for each combination out of the selection of electric drive assemblies and the selection of pump assemblies, a collar portion with the same outer diameter can be provided on the side of the pump housing and a rotor cup with the same inner diameter can be provided on the side of the motor rotor.
By specifying the ratio of the diameter between the collar portion and the rotor cup, a spaced interface can be defined between the components in the radial direction. This mutual radial spaced interval is preferably selected to be small. A defined small spaced interval in the case of each selection combination ensures optimum utilisation of the installation space in the pump housing and the objective of a universal yet compact pump structure is achieved.
Furthermore, said specification of the diameters renders it possible to use, for all electric drive assemblies, the same main body for the motor rotor. The rotor cup of the rotor needs merely to be adapted, where appropriate, in terms of an axial length. Furthermore, the outer diameter of the rotor cup of such an identical main body of the motor rotor for all electric drive assemblies can be adapted to a relevant stator of a respective electric drive assembly merely by means of modified provision and attachment of magnet bodies as rotor poles.
According to one aspect of the invention, for each combination out of the selection of electric drive assemblies and the selection of pump assemblies, on the side of the pump housing, a collar portion with the same inner diameter, the same shaft bearing and a pump shaft with the same outer diameter can be provided.
This ensures that the same shaft bearing or a shaft bearing with the same outer diameter can always be used for each selection combination of the assemblies, thus achieving optional standardisation of the modular system. Therefore, this also provides the possibility of using, for different pump assemblies in combination with electric drive assemblies of the dry runner type, a similar or the same shaft seal which is arranged within the collar portion.
According to one aspect of the invention, for each combination out of the selection of electric drive assemblies and the selection of pump assemblies, a motor chamber with the same inner circumference portion can be formed in the pump housing.
By specifying an identical inner diameter and optionally a step portion, it is possible to provide, for all stator types out of the selection of electric drive assemblies, a fixing arrangement, whereby design and manufacture of the pump housing, or at least a housing portion thereof, and assembly are simplified. On the other hand, an identical outer circumference of each stator yoke with respect to the pump housing can be provided with a varying width in the axial direction.
According to one aspect of the invention, the motor chamber can be closed to one axial side of the pump housing by a motor cover with an integral pin-fin heat sink in which control electronics may be accommodated for an electric drive assembly.
By means of the common feature of a cover for the motor chamber, a uniform assembly sequence permitted when assembling the electric drive assemblies. A pin-fin cooler which can be integrated in each cover can be the same, just like a universal accommodation at the inner side which is suitable for bringing different control electronics of each electric drive assembly into thermal contact. If the pump has a specified housing circumference or a contour for accommodating the different stator types of the electric drive assemblies, the entire cover for all or many selection combinations of the assemblies can be the same component, wherein a feature of the pin-fin cooler is omitted for liquid-cooled drives.
According to one aspect of the invention, at least one part of the pump housing that includes the through-hole and the collar portion, and/or the motor cover is made of a material suitable for impact extrusion, preferably cold impact extrusion.
Impact-extruded parts have, by reason of the provision method, a smaller formation of air bubbles and cavities as well as inclusions of foreign bodies and have better thermal and mechanical properties than conventional die cast parts. A better thermal conductivity coefficient has a particularly advantageous effect in a housing portion between the electric drive assembly and the pump assembly because an improved thermal transition of the electric power loss from the stator of the electric drive assembly to the pump chamber can thus be achieved. In the pump chamber, the waste heat is rapidly dissipated by the mass flow of the conveyed medium. As a result, cooling of the stator is improved. A better thermal conductivity likewise has an advantageous effect in the region of the cover of the motor chamber, wherein, in particular, an improved thermal transition of the control electronics via the pin-fin cooler to the environment can be achieved.
A higher level of mechanical strength, in particular stiffness of impact-extruded bodies in comparison with a conventional die cast body, such as an aluminium die cast, also brings about advantages in the region of the accommodation of the shaft bearing, i.e. the collar portion. In particular, in the case of displacement pumps, tilting moments occur at the pump shaft which are absorbed by the pump housing via the shaft bearing. In comparison with a conventional die cast part, the collar portion can be designed for accommodating the shaft bearing in order to achieve a comparable level of mechanical stiffness with a smaller wall thickness. In turn, a smaller wall thickness in this and further housing portions saves material costs and weight.
The invention will be explained in greater detail hereinafter with reference to drawings relating to various embodiments arising from various selection combinations out of the assemblies of the modular system. In the drawings:
A rear side of the pump chamber 22 behind the impeller 21a is formed by the illustrated part of a pump housing 20. The pump housing 20 has a through-hole for a pump shaft 31 which is sealed with respect to the pump chamber 22 by means of a shaft seal 33. The pump shaft 31 extends from the impeller 21a through the through-hole of the pump housing 20 to an electric drive assembly 1 and is mounted on the pump housing 20 by means of a single shaft bearing 32. The shaft bearing 32 has two rolling bearing sets with spherical rolling bodies in order to be able to absorb radial and axial forces and also tilting moments of the pump shaft 31 within a single shaft bearing 32. The shaft bearing 32 is fitted into a collar portion 23 of the pump housing 20. The collar portion 23 protrudes concentrically with respect to the through-hole of the pump housing 20 to the side of the electric drive assembly 1.
The electric drive assembly 1 comprises a motor rotor 11 and a stator 12 as well as control electronics 14. On the same side, the pump housing 20 has a cylindrical outer wall which surrounds a motor chamber 10 for accommodating the electric drive assembly 1. The outer housing wall of the pump housing 20 extends concentrically with respect to the collar portion 23 and so an annular volume for accommodating the stator 12 of the electric drive assembly 1 is provided in the motor chamber 10. An outer circumferential edge of the stator 12 is in contact with a step portion of an inner surface of the motor chamber 10 and is thus radially and axially fixed.
The motor rotor 11 is fixed on a free end of the pump shaft 31 which projects out of the collar portion 23. The motor rotor 11 has, at a radially outer portion, a rotor cup 13 which axially intersects the collar portion 23 of the pump housing 20 and encircles same radially outside. An axial dimension and position of the rotor cup 13 corresponds to a facing inner surface of the stator 12. The rotor cup 13 serves as a magnet carrier for the rotor poles. Therefore, a hollow cylinder which corresponds substantially to the outer diameter of the collar portion 23 plus a spacing gap remains within the rotor cup 13.
The windings of the field coils of the stator 12 extend to the left and right of the stator yoke into the motor chamber 10. The pump housing 20 is open on an axial side of the motor chamber 10. The opened side of the pump housing 20 is closed by means of a motor cover 24. The motor cover 24 has, on an outer side, a multiplicity of parallel-protruding pins and forms a so-called pin-fin heat sink. On the inner side, the motor cover 24 has a surface which is in thermal contact with control electronics 14 of the electric drive assembly 1. In particular, the control electronics 14 has electronic modules or power electronics, such as e.g. capacitors and transistors, which are wired on a printed circuit board and the printed circuit board is in surface contact with the accommodation surface of the motor cover 24. Arranged between the pump housing 20 and the motor cover 24 is a connector which is illustrated on the upper housing side and guides lines to an electric power supply.
On a rear side of the radial impeller 21a, the pump housing 20 has a pressure equalisation chamber 26, over the circumference of which a pressure equalisation membrane 27 is tensioned. A rear side of the pressure equalisation chamber 26 is connected to the motor chamber 10 via a bore. The motor chamber 10 is filled with a dielectric cooling medium which is introduced into the pump housing 20 through a closable opening. The dielectric cooling medium surrounds the field coils of the stator 12 and discharges waste heat from the power loss of the stator via the pump housing 20 to the environment and in particular to a conveyor flow in the pump chamber 22 of the pump assembly 2.
Pressure fluctuations which arise in the closed volume of the motor chamber 10 by reason of the temperature fluctuations in the electric drive assembly 1 are transmitted by the pressure equalisation chamber 26 via the pressure equalisation membrane 27 to the pump chamber 20 and so a pressure equilibrium is achieved between the motor chamber 10 and the pump chamber 22.
The first embodiment and the second embodiment have the same pump shaft 31 and the shaft bearing 32. Furthermore, parts of the pump housing 20 for accommodating the electric drive assembly 1, such as the collar portion 23 and an outer wall of the pump chamber 10, as well as the motor cover 24, correspond with one another. Likewise, an inner diameter of the rotor cup 13 on the motor rotor 11 corresponds to that of the preceding embodiments.
In comparison with the preceding embodiments, the stator 12 of the electric drive assembly 1 has a smaller drive capacity. The stator 12 of this embodiment has been configured in such a way that an axial dimension including the field coils has been reduced in comparison with the preceding embodiments. However, parts of the pump housing 20 for accommodating the electric drive assembly 1, such as the collar portion 23 and an outer wall of the pump chamber 10, as well as the motor cover 24, also correspond to those of the preceding embodiments. Likewise, an inner diameter of the rotor cup 13 on the motor rotor 11 corresponds to that of the preceding embodiments. The shaft bearing 32 and a blank as an initial body of the pump shaft 31 are identical.
The pump assembly 2 is a displacement pump of the gerotor type. The pump rotor 21 is designed as a gerotor inner element 21c, of which the outer rotor toothing is in meshing engagement with an inner rotor toothing of a rotatable gerotor outer element 28. The pump cover 25 has a central pump inlet. The pump outlet is not illustrated in this sectional view. Moreover, further details of the pump assembly 2 have not been described further in order to reduce the length of the disclosure to essential features of the invention.
The electric drive assembly 1 of the fourth embodiment has a larger drive capacity, in particular a high drive torque, corresponding to the requirement of a displacement pump, in comparison with the preceding embodiments. The stator 12 of the electric drive assembly 1 of this embodiment has been configured in such a way that an axial dimension including the field coils is longer in comparison with the preceding embodiments. Accordingly, a diameter of the field coils of the stator 12 and an axial dimension of the magnetic poles on the rotor cup 13 are larger than in the case of the preceding embodiments. However, an axial dimension of parts of the pump housing 20 for accommodating the electric drive assembly 1, such as the collar portion 23 and an outer wall of the pump chamber 10, as well as the motor cover 24, also correspond to those of the preceding embodiments. Likewise, an inner diameter of the rotor cup 13 on the motor rotor 11 corresponds to that of the preceding embodiments. The shaft bearing 32 and a blank as an initial body of the pump shaft 31 are identical.
The drive capacity of the electric drive assembly 1 corresponds substantially to that of the fourth embodiment, but it is not sealed by means of a shaft seal 33 and therefore is in contact with the conveyed oil. The motor cover 24 differs from the fourth embodiment in that it delimits the control electronics 14 from the oil in the motor chamber 10. In turn, the control electronics 14 can be covered with respect to the outer side by a cover, not illustrated. The shaft bearing 32 and a blank as an initial body of the pump shaft 31 are identical.
The rotary piston 29 is driven by means of a crank pin on a rotary plate 21d which engages into a long hole in the rotary piston 29. The pump rotor 21 of the sixth embodiment is thus designed as a rotary plate 21d comprising a crank pin.
The stator 12 of the electric drive assembly 1 in the sixth embodiment has a smaller drive capacity in comparison with the fourth and fifth embodiment of an oil pump. The stator 12 of this embodiment has been configured in such a way that an axial dimension including the field coils has been reduced in comparison with the fourth and fifth embodiments. However, parts of the pump housing 20 for accommodating the electric drive assembly 1, such as the collar portion 23 and an outer wall of the pump chamber 10, as well as the motor cover 24, also correspond to those from preceding embodiments. Likewise, an inner diameter of the rotor cup 13 on the motor rotor 11 corresponds to that of the preceding embodiments. The shaft bearing 32 and a blank as an initial body of the pump shaft 31 are identical.
A common aspect of all embodiments of the pumps consisting of the modular system is that the electric drive assembly 1, the pump housing 20 of the pump assembly 2 and the shaft bearing assembly 3 are arranged in an integrated manner in the pump structure such that they axially intersect one another. The same sequence of components of the assemblies is always provided in the radial direction from inside to outside, namely the pump shaft 31, the shaft bearing 32, the collar portion 23, the rotor cup 13, the stator 12 and an outer wall of the pump housing 20 which defines the motor chamber 10.
Whether a shaft seal 33 is used and whether the shaft seal 33 is arranged in front of or behind the shaft bearing 32 can be varied by positioning the shaft seal 33 in the standard collar portion 23 for different types of electric drive assemblies 1, such as dry runners and wet runners, using assembly procedures without having to manufacture different moulded parts for the pump housing. The shaft bearing 32 and a pump shaft 31 or a blank thereof having the same diameter can be provided in each pump from a selection combination of the assemblies consisting of the same components.
In order to achieve the largest possible number of common components for a universal integration of individual selection combinations amongst the assemblies, a portion of the pump housing 20 which delimits the pump chamber 22 and the motor chamber 10 and comprises the collar portion 23 and a step portion, on the inner surface of which the stator 12 is axially fixed, is designed having the same radial dimensions and is manufactured as a standard impact-extruded part with or without the feature of a pin-fin cooler. Likewise, the motor cover 24 is designed for several embodiments having the same dimensions and is manufactured as a standard impact-extruded part, wherein for liquid-cooled electric drive assemblies 1 of the wet runner type an integrated pin-fin heat sink to the outer side can be omitted. Furthermore, the motor rotor 11 comprising the rotor cup 13 having the same radial dimensions is formed at least prior to the provision of rotor poles with the same inner diameter and is manufactured as a standard deep-drawn part or sintered part having good magnetic properties.
The adaptation to the electric drive assemblies 1 is thus effected by means of a length of the axial dimension of the pump housing 20 and the rotor cup 13 and by providing the magnetic poles in dependence upon the field coils of a selected stator 12. Moreover, a configuration of the pump assembly 2 in dependence upon the selected combination of the pump rotor 21 and pump chamber 22 in relation to the pump housing 20 is standardised by implementing specific features, such as a pump inlet and pump outlet or a spiral housing, not on the side of the aforementioned standard portion of the pump housing 20 but instead on the side of an individual pump cover 25.
LIST OF REFERENCE SIGNS1 electric drive assembly
2 pump assembly
3 shaft bearing assembly
10 motor chamber
11 motor rotor
12 stator
13 rotor cup
14 control electronics
20 pump housing
21a radial impeller
21b peripheral wheel
21c gerotor inner element
21d rotary plate with crank pin
22 pump chamber
23 collar portion
24 motor cover
25 pump cover
26 pressure equalisation chamber
27 pressure equalisation membrane
28 gerotor outer element
29 rotary piston
31 pump shaft
32 shaft bearing
33 shaft seal
Claims
1. A modular system for a pump structure for the axial integration of an electric drive assembly at a pump assembly including:
- a selection of electric drive assemblies with different drive capacities;
- a selection of pump assemblies with different volumetric capacities and/or different configurations; and
- a shaft-bearing-assembly including a pump shaft and a shaft bearing with at least two rolling bearing sets, the shaft bearing supporting the pump shaft between a motor rotor of the electric drive assembly and a pump rotor of the pump assembly at a pump housing of the pump assembly; wherein
- the selection of pump assemblies jointly comprises a collar portion at the pump housing which accommodates the shaft bearing in a through-hole of the pump housing and protrudes to an accommodation side for an electric drive unit; and
- the selection of pump assemblies differs with respect to the pump rotor and/or a pump chamber;
- the selection of drive assemblies jointly comprises a motor rotor which is formed at a radially external section in the shape of a rotor cup, the rotor cup radially encircling and axially intersecting the collar portion that each pump housing of the selection of drive assemblies jointly comprises; and
- the selection of drive assemblies differs with respect to a stator; and wherein
- for each combination of the selection of electric drive assemblies and the selection of pump assemblies, at least one radial dimension of the pump shaft, the shaft bearing, the collar portion and/or the rotor cup are the same.
2. The modular system according to claim 1, wherein for each combination out of the selection of electric drive assemblies and the selection of the pump assemblies, a collar portion with the same outer diameter is provided on the side of the pump housing and a rotor cup with the same inner diameter is provided on the side of the motor rotor.
3. The modular system according to claim 1, wherein for each combination out of the selection of electric drive assemblies and the selection of the pump assemblies, on the side of the pump housing, a collar portion with the same inner diameter, the same shaft bearing and a pump shaft with the same outer diameter are provided.
4. The modular system according to claim 1, wherein for each combination out of the selection of electric drive assemblies and the selection of the pump assemblies, a motor chamber with the same inner circumference is formed in the pump housing.
5. The modular system according to claim 4, wherein the motor chamber is closed to one axial side of the pump housing by a motor cover with an integral pin-fin heat sink in which control electronics may be accommodated for an electric drive assembly.
6. The modular system according to claim 4, wherein at least one part of the pump housing that includes the through-hole and the collar portion, and/or the motor cover is made of a material suitable for impact extrusion, preferably cold impact extrusion.
Type: Application
Filed: Dec 12, 2018
Publication Date: Feb 11, 2021
Inventors: Conrad Nickel (Troistedt), Franz Pawellek (Lautertal)
Application Number: 16/979,778
