IMPELLER MACHINE

Description

[0001] The invention relates to an impeller machine comprising an impeller housing, a motor housing, and an aerostator extending between the impeller housing and the motor housing. The motor housing is arranged within an interior space of the impeller housing. The impeller machine includes an aerorotor for generating an airflow along an annular space enclosed between the impeller housing and the motor housing.

[0002] Operating an impeller machine generates a significant amount of heat. For example, if 5-10% of the drive power in an impeller machine with a power output on the order of a few kilowatts is converted into heat, components of the impeller machine can overheat if the heat is not adequately dissipated.

[0003] Document EP 3 579 391 A1 discloses a fan motor with an inner housing, wherein a heat dissipation vane is formed on an outer circumferential surface of the inner housing for guiding the air drawn into an inlet and then directed between the inner housing and an outer housing.

[0004] Document WO 2008 109 022 A1 discloses a fan motor with an aerostator and with separate heat dissipation fins.

[0005] The invention is based on the objective of providing an impeller machine with improved heat dissipation. This objective is achieved by the features of the independent claim. Advantageous embodiments are specified in the dependent claims.

[0006] In the impeller machine according to the invention, the outer surface of the motor housing is provided with a cooling fin that extends from the motor housing to a peripheral end. An upstream section of the cooling fin is arranged in a different circumferential position than a downstream section of the cooling fin.

[0007] The invention has recognized that the cooling effect of a cooling fin is improved if the cooling fin does not extend parallel to the axial direction of the impeller machine, but has a course on the outside of the motor housing, in which the circumferential position of the cooling fin changes with the course of the cooling fin.

[0008] For optimal cooling, a long cooling fin is advantageous. The cooling fin can extend axially over at least 60%, preferably at least 80%, and more preferably at least 90% of the length of the motor housing. In one embodiment, the upstream end of the cooling fin coincides with the upstream end of the motor housing. The downstream end of the cooling fin can also coincide with the downstream end of the motor housing. The motor housing is defined as the component that surrounds and holds the motor. A housing cover, if attached to the motor housing, is a separate component.

[0009] The height of the cooling fin corresponds to the distance between the base of the cooling fin and its peripheral end. The peripheral end is a free end of the cooling fin that is not connected to and spaced from the impeller housing. Thus, the cooling fin does not form a connection between the motor housing and the impeller housing. The line connecting the peripheral end and the base of the cooling fin, relative to a given axial position of the impeller, can extend radially along the impeller. In other words, the cooling fin is perpendicular to the outside of the motor housing and extends straight outwards. This can be true for all axial positions of the cooling fin.

[0010] An impeller machine according to the invention is an axial turbomachine. The airflow driven by the aerorotor has a flow direction parallel to the axis of the aerorotor. The aerorotor has rotor blades which, with respect to the axis, are arranged in the same radial section as the annular space located between the impeller housing and the motor housing.

[0011] The distinction between impeller machines and other types of turbomachinery is made based on the in Fig. 8 The Cordier diagram shown plots the speed number σ against the diameter number δ. The impeller machines according to the invention differ from radial and turbomachines by having a higher speed number σ and a lower diameter number δ. They also differ from unjacketed propeller machines by having a lower speed number σ and a higher diameter number δ. The speed number σ of the impeller machine according to the invention can range from 1.8 to 10. The diameter number δ of the impeller machine according to the invention can range from 0.8 to 1.5.

[0012] The running number σ used in the Cordier diagram is a dimensionless parameter defined as follows. σ = 2 π n Q 2 Y 3 / 2

[0013] The diameter number δ is also a dimensionless parameter, which is defined as follows. δ = π 2 D 2 Y Q 2 4

[0014] Both formulas take into account the volume flow rate Q and the specific head work Y. If these two quantities are considered predetermined by the intended use of the turbomachine, then the rotational speed σ depends only on the rotational speed n and the diameter number δ only on the diameter D of the aerorotor. Further explanations can be found, for example, in Epple et al., A theoretical derivation of the Cordier diagram for turbomachines, Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 2011 225: 354.

[0015] The annular space enclosed between the impeller housing and the motor housing may have a section with a constant cross-section. This section may extend over at least 50%, preferably at least 70%, and more preferably at least 80% of the axial length of the annular space. Constant cross-section means that the distance between the inside of the impeller housing and the outside of the motor housing is constant, and that the outer and inner diameters of the annular space are constant. Aerostators and / or cooling fins within the annular space are not considered a change in the cross-section in this sense. The aerorotor may have rotor blades which, viewed in the radial direction of the impeller machine, cover the constant cross-section of the annular space.

[0016] The impeller machine can comprise a single component in which the motor housing and cooling fins are integrally joined. This component can be, for example, a casting, a 3D-printed part, or a milled part.

[0017] The motor housing can essentially be cylindrical. The height of the cooling fin between the outer surface of the motor housing and its peripheral end can be between 2% and 20%, preferably between 5% and 15%, relative to the diameter of the motor housing. Relative to the radial extent of the annular space between the inner surface of the impeller housing and the outer surface of the motor housing, the height of the cooling fin can also be between 2% and 20%, preferably between 5% and 15%. While a greater cooling fin height might further improve the cooling effect, it also creates resistance to the airflow, so a greater cooling fin height would reduce the efficiency of the impeller machine. If the diameter of the motor housing changes along the length of the impeller machine, the specified value refers to the largest diameter of the motor housing.If the radial dimensions of the annular space change along the length of the impeller, the specification refers to the largest radial dimension of the annular space. The cooling fin can have a constant height along its length. If the height of the cooling fin changes along the length of the impeller, the specification refers to the greatest height of the cooling fin.

[0018] The cooling fin's path along the outside of the motor housing can be non-linear. An upstream section of the cooling fin can form a larger angle with a longitudinal line than a downstream section. A longitudinal line is defined as a line extending along the length of the motor housing on its outside such that it forms a plane in which both the axis of the impeller and the longitudinal line are located. For the purposes of this invention, a longitudinal line has a constant circumferential position.

[0019] The upstream end of the cooling fin can form an angle of more than 10°, for example, an angle between 10° and 50°, preferably an angle between 20° and 40°, with the longitudinal line. The downstream end of the cooling fin can form an angle of less than 8°, preferably an angle of less than 5°, with the longitudinal line. Preferably, the downstream end of the cooling fin forms an angle of more than 0° with the longitudinal direction, for example, an angle between 1° and 5°. In one embodiment, the downstream end of the cooling fin is aligned parallel to the longitudinal line. A section of the cooling fin parallel to the longitudinal line preferably comprises less than 20%, more preferably less than 10%, and further preferably less than 5% of the length of the cooling fin. The cooling fin can have a continuous curvature.The curvature can be designed such that the angle between the cooling fin and the longitudinal line decreases continuously from the upstream end to the downstream end of the cooling fin. The continuous curvature can extend over at least 70%, preferably at least 80%, and more preferably at least 90% of the length of the cooling fin. The cooling fin can be designed such that there is no longitudinal line that is intersected twice by the cooling fin.

[0020] Inside the motor housing is a motor that drives a shaft connected to the aerorotor. The aerorotor propels the airflow through the annular space between the motor housing and the impeller housing, with the airflow emitted by the aerorotor having an axial and a circumferential component. The upstream end of the cooling fin can be oriented so that the airflow enters the annular space substantially parallel to the end of the cooling fin. The cooling fin, with its curved shape along the annular space, can help guide the airflow so that it exits the annular space substantially axially. The aerorotor, located upstream of the motor housing, can be positioned within the impeller housing.

[0021] The downstream end of the motor housing can extend rearward beyond the downstream end of the impeller housing. The cooling fin can include a downstream section that lies outside the annular space surrounded by the impeller housing. This has the advantage that the airflow in the motor housing area is still guided even as it transitions from the annular space to the surrounding environment.

[0022] The impeller machine can comprise multiple cooling fins with the aforementioned characteristics. A cooling channel open to one side can be formed between two adjacent cooling fins. The cooling fins can be distributed around the circumference of the motor housing. The cooling fins within the multiple cooling fins can be identically shaped. Two cooling fins are identically shaped if they can be aligned by rotating the impeller machine around its central axis. The lateral distance between two cooling fins can be between 25% and 200% of the height of the cooling fins.

[0023] The impeller engine features an aerostator extending between the impeller housing and the motor housing, holding the motor housing in position relative to the impeller housing. The aerostators may extend along a curved path, such that an upstream end of the aerostator forms a larger angle with the longitudinal axis than a downstream end. The aerostator may form an airfoil profile effective against the airflow through the annular space. The impeller engine may be equipped with several such aerostators, for example, three. The aerostators may be evenly distributed around the circumference of the motor housing.

[0024] At least one cooling fin can be arranged between any two adjacent aerostators. Preferably, a plurality of cooling fins are arranged between any two adjacent aerostators, for example, at least three cooling fins, preferably at least five cooling fins, and more preferably at least eight cooling fins. This can apply to each pair of adjacent aerostators.

[0025] To further improve cooling, the impeller engine can include a cooling air duct extending through the interior of the engine housing. The cooling air duct can have an inlet opening located at a downstream end of the engine housing. The cooling air duct can have an outlet opening located upstream of the inlet opening. The outlet opening can extend through the wall of the engine housing and open into the annular space. The distance between the outlet opening and the inlet opening can be greater, preferably at least twice as great, as the distance between the outlet opening and the aerorotor. The impeller engine can have multiple such cooling air ducts.

[0026] The outlet of the cooling air duct can open into a region of the annular space where, during operation of the impeller machine, a negative pressure exists that is lower than the pressure at the inlet. This makes it possible to drive a cooling airflow along the cooling air duct by means of a pressure difference between the inlet and outlet openings.

[0027] The negative pressure in the annular space can result from the airflow having a higher velocity on one side of the aerostator than on the other. The outlet opening of the cooling air duct can be located adjacent to the negative pressure side of an aerostator. The distance between the outlet opening and the positive pressure side of the next aerostator can be at least twice, preferably at least three times, the distance between the outlet opening and the negative pressure side of the adjacent aerostator. It is also possible for the aerostator to have an internal cavity connected to the interior of the engine housing, and for the outlet opening to be located in a wall of the aerostator facing the negative pressure side.

[0028] Alternatively, the cooling fins according to the invention can also be attached to a motor housing whose interior is free of a cooling channel. In particular, the impeller machine can comprise a motor housing whose interior is sealed dustproof and / or watertight. Effective cooling can thus also be achieved in impeller machines that are used in adverse environmental conditions and for which internal cooling is therefore not possible.

[0029] An electrically driven motor can be arranged inside the motor housing. The electric motor can be powered by an external energy source. The motor can drive a motor shaft extending axially along the impeller. An aerorotor can be connected to the motor shaft and rotated with it. The aerorotor can include rotor blades extending substantially radially outward. The rotor blades can be arranged and dimensioned to sweep the radial area defined by the annular space between the impeller housing and the motor housing.

[0030] The aerorotor can be located in an upstream section of the annular space, so that the airflow driven by the aerorotor first passes over the aerorotor and then through the longer section of the annular space. The upstream end of the impeller is called the front end, and the downstream end is called the rear end. The impeller housing can form a closed shell extending circumferentially around the annular space. An upstream section of the impeller housing can be located radially outside the aerorotor, so that the aerorotor is located inside the impeller housing.

[0031] The impeller machine includes an aerostator that holds the motor housing relative to the impeller housing. A cable may run inside the aerostator. This cable could be a power supply cable that provides electrical energy to the impeller machine's motor. It could also be a sensor cable or a control cable that transmits signals between the interior of the motor housing and the exterior of the impeller housing.

[0032] The impeller machine can include multiple aerostators extending between the impeller housing and the motor housing. These multiple aerostators can be arranged in the same axial position. The positions of the aerostators can be evenly distributed around the circumference of the impeller machine. For example, three aerostators can be distributed around the circumference of the impeller machine. The aerostators can have an airfoil profile to guide and steer the airflow generated by the aerorotor.

[0033] The annular space can have an axial extension that stretches from the plane of the aerorotor to a downstream end of the impeller housing. The aerostators can project rearward beyond the impeller housing with their rear end. A front section of the aerostator can be located inside the impeller housing.

[0034] The invention is described below by way of example with reference to the accompanying drawings and advantageous embodiments. The drawings show: Fig. 1: an impeller according to the invention; Fig. 2: a schematic sectional view of the impeller machine made of Fig. 1 Fig. 3: a schematic representation of a cooling fin of an impeller machine according to the invention; Fig. 4: a simplified sectional view of a motor housing according to the invention; Fig. 5: an alternative embodiment of an impeller machine according to the invention in a partially disassembled state; Fig. 6: the impeller machine made of Fig. 5 in the assembled state; Fig. 7: a schematic representation of an aerostator of an impeller machine according to the invention; Fig. 8: a Cordier diagram for distinguishing different types of turbomachinery.

[0035] An impeller machine according to the invention comprises, according to Fig. 2 An aerorotor 14 is arranged in an impeller housing 15. An electric motor 16 drives a shaft 17, causing the aerorotor 14, connected to the shaft 17, to rotate. The shaft 17 extends along a central axis 18 of the impeller machine. The motor 16 is held in a motor housing 19, which is located inside the impeller housing 15.

[0036] An impeller machine according to the invention is a high-efficiency axial turbomachine, which in the Cordier diagram ( Fig. 8 The impeller machine according to the invention has a rotational speed σ between 1.8 and 10 and a diameter number δ between 0.8 and 1.5. It differs from high-efficiency radial turbomachines by having a higher value for the rotational speed σ and a lower value for the diameter number δ. It also differs from unjacketed propeller machines by having a lower value for the rotational speed σ and a higher value for the diameter number δ. A plurality of aerostators 20 are formed in an annular space 31, which is enclosed radially outside the motor housing 19 and radially inside the impeller housing 15. These aerostators hold the motor housing 19 in position relative to the impeller housing 15. The aerorotor 14 comprises a plurality of rotor blades 21 that rotate around an upstream end of the annular space 31.The rotation of the aerorotor 14 generates an airflow that extends from the aerorotor 14 through the annular space 31 to the opposite, downstream end of the impeller machine. The upstream end is the front end of the impeller machine, and the downstream end is the rear end of the impeller machine.

[0037] The front end 28 of the impeller housing 15 is located further upstream than the front end 22 of the motor housing 19. The impeller housing 15 surrounds the aerorotor 14, which is located upstream of the motor housing 19, so that the aerorotor rotates inside the impeller housing 15.

[0038] The rear end 23 of the motor housing 19 is located further downstream than the rear end of the impeller housing 29. In this way, the motor housing 19 includes a rear section that extends backward beyond the impeller housing 15.

[0039] Cooling fins 21 are formed on the outside of the motor housing 19, extending from the motor housing 19 to a peripheral end 39 and lengthwise between the front end 22 and the rear end 23 of the motor housing. Fig. 2 The cooling fins 21 are only shown schematically. The airflow in the annular space 31 sweeps across the surface of the cooling fins 21 and carries heat away from them. The heat emitted by the motor during operation of the impeller propagates through the motor housing 19 to the cooling fins 21, where it is absorbed by the airflow.

[0040] Between each pair of adjacent aerostators 20, a plurality of cooling fins 21 are formed. In the embodiment shown below. Fig. 1 Eleven cooling fins are arranged between the two aerostators 20 visible in the figure. With a total of three aerostators 20, this results in thirty-three cooling fins 21 distributed around the circumference of the motor housing 19. The cooling fins 21 are identically shaped and have a constant distance between them, so that a cooling channel with a substantially constant cross-section, open to one side, extends between each pair of cooling fins 21. The airflow can follow the cooling channels without significant turbulence occurring.

[0041] Viewed longitudinally, a larger section of the cooling fins 21 is arranged within the annular space 31 between the impeller housing 15 and the motor housing 19. A shorter section of the cooling fins 21 projects rearward out of the annular space 31. The cooling fins 21 terminate at the rear end of the motor housing 19. A housing cover 30, which covers the motor at the rear, is attached to the rear end of the motor housing 19.

[0042] The cooling fins 21 extend longitudinally along a curved path from the front end 22 to the rear end 23 of the motor housing 19. The longitudinal direction of the cooling fin 21, according to the schematic representation in Fig. 3 At the front end 22 of the motor housing 19, the cooling fin forms an angle 25 of approximately 45° with the longitudinal line 24. The angle between the longitudinal direction of the cooling fin 21 and the longitudinal line 24 decreases continuously with increasing distance from the front end 22 of the motor housing 19. At the rear end 23 of the motor housing 19, the angle between the longitudinal direction of the cooling fin 21 and the longitudinal line 24 is still approximately 5°.

[0043] Arrow 27 indicates the direction of rotation with which the aerorotor 14 passes this circumferential section of the motor housing 19. The angle between the longitudinal direction of the cooling fin 21 at the front end 22 of the motor housing 19 and the direction of movement of an adjacent part of the aerorotor 14 is less than 90°.

[0044] Viewed in cross-section, the cooling fins 21 are shown in the schematic diagram in Fig. 4 Essentially rectangular. The cooling fins 21 have a cross-section that is essentially constant along their length. The cooling fins 21 form a right angle with the surface of the motor housing 19. The cooling fins 21 extend from the outside of the motor housing 19 to a free end 39.

[0045] In the embodiment according to the Fig. 5 und 6 Each aerostator 20 has an internal cavity that is open towards the rear end. The cavity extends over the entire radial extent of the annular space 31. Cables 32 are routed within this cavity, extending from the interior of the motor housing 19 to the exterior of the impeller housing 15. The cables 32 include power supply lines that transmit electrical energy from a battery located outside the impeller machine to the electric motor 16 inside the motor housing 19. The cables 32 may also include control lines and / or sensor lines that transmit signals during operation of the impeller machine. A control board 34 is located at the rear end of the motor housing 19, which controls the motor 16. By routing the cables 32 inside the aerostators 20, the airflow between the cooling fins 21 is prevented from being obstructed by cables.

[0046] After the cables 32 are inserted, the aerostators 20 are covered at the rear with a housing cover 30. The housing cover 30 is flush with the body of the aerostators 20 and continues the contour of the aerostators 20 to the rear. This state of the impeller machine is in Fig. 6 shown.

[0047] At its rear end, the housing cover 30 is provided with an inlet opening 33 for a cooling air duct. The cooling air duct extends from the inlet opening 33 through the interior of the motor housing 19 to an outlet opening 35 in the annular space 31. The outlet opening 35 extends through the wall of the motor housing 19 and opens into an area where a negative pressure exists during operation of the impeller motor 19. (See schematic diagram below.) Fig. 7The outlet opening 35 of the cooling air duct is located on the low-pressure side of an aerostator 20. The outlet opening 35, formed in the wall of the aerostator, is connected to a cavity inside the aerostator 20, which in turn is connected to the interior of the motor housing 19. When a low pressure is present at the outlet opening 35, while essentially atmospheric pressure prevails in the area of ​​the inlet opening 33, a cooling airflow is generated through the cooling air duct by the pressure difference during operation of the impeller engine.

[0048] For effective internal cooling of the electric motor 16, the impeller machine includes a plurality of outlet openings 35. Each of the three aerostators 20 is assigned an outlet opening 35, with the outlet opening 35 being located on the low-pressure side of the aerostator 20. The cooling air can enter at the rear end of the impeller machine via one or more inlet openings 33.

[0049] For the assembly of the impeller machine according to the invention, the impeller housing 15 and the motor housing 19, which is connected to it via the aerostators 20, are provided as a single component. The cooling fins 21 on the outside of the motor housing 19 are an integral part of this single component. The motor housing 19 has a compartment inside designed to accommodate the electric motor 16. The electric motor 16, with its cables 32 and control board 34, is brought up to the rear of the motor housing 19 and inserted into it. During insertion, the cables 32 are placed into the cavities of the aerostators 20, which are accessible from the rear. The cables 32 are then fixed in position with adhesive.

[0050] When the electric motor 16 has reached its final position in the motor housing 19 and is resting against a stop of the motor housing 19, the aerorotor 14 is placed onto the shaft 17 of the electric motor 16 from the front and screwed to the shaft 17.

[0051] The cover component 38 is then placed onto the motor housing 19 from the rear and screwed to the motor housing 19. This step simultaneously closes the cavities of the aerostators 20, so that the cables 32 are arranged in a completely enclosed cavity.

Claims

1. Impeller machine having an impeller housing (15), having a motor housing (19) and having an aero stator (20) which extends between the impeller housing (15) and the motor housing (19), wherein the motor housing (19) is arranged in an interior of the impeller housing (15), and having an aero rotor (14) for generating an airflow along an annular space (31) enclosed between the impeller housing (15) and the motor housing (19), wherein the motor housing (19) is provided on its outer side with a cooling rib (21), wherein the cooling rib (21) rises from the motor housing (19) to a peripheral end (39), characterized in that an upstream portion (36) of the cooling rib (21) is arranged in a different peripheral position than a downstream portion (37) of the cooling rib (21).

2. Impeller machine according to Claim 1, characterized in that the cooling rib (21) extends in the axial direction (18) over at least 60%, preferably at least 80%, more preferably at least 90% of the length of the motor housing (19).

3. Impeller machine according to Claim 1 or 2, characterized in that the height (38) of the cooling rib (21) between the outer side of the motor housing (19) and the peripheral end (39) is between 2% and 20%, preferably between 5% and 15% of the diameter of the motor housing (19).

4. Impeller machine according to any one of Claims 1 to 3, characterized in that the height (38) of the cooling rib (21) between the outer side of the motor housing (19) and the peripheral end (39) is between 2% and 20%, preferably between 5% and 15%, of the radial extent of the annular space (31) between the inner side of the impeller housing (15) and the outer side of the motor housing (19).

5. Impeller machine according to any one of Claims 1 to 4, characterized in that the angle (25) that an upstream portion (36) of the cooling rib (21) forms with a longitudinal line (24) is greater than the angle (24) that a downstream portion (37) of the cooling rib (21) forms with the longitudinal line (24).

6. Impeller machine according to any one of Claims 1 to 5, characterized in that an upstream end of the cooling rib (21) forms an angle (25) between 10° and 50°, preferably an angle (25) between 20° and 40°, with the longitudinal line (24).

7. Impeller machine according to any one of Claims 1 to 6, characterized in that a downstream end of the cooling rib (21) forms an angle (26) of less than 8°, preferably an angle (25) of less than 5°, with the longitudinal line (24).

8. Impeller machine according to any one of Claims 1 to 7, characterized in that the angle (25, 26) between the cooling rib (21) and the longitudinal line (24) continuously decreases from the upstream end to the downstream end of the cooling rib (21).

9. Impeller machine according to any one of Claims 1 to 8, characterized in that the cooling rib (21) comprises a downstream portion (37) located outside the annular space (31) surrounded by the impeller housing (15) .

10. Impeller machine according to any one of Claims 1 to 9, characterized by a plurality of cooling ribs (21) distributed over the periphery of the motor housing (19).

11. Impeller machine according to any one of Claims 1 to 10, characterized by a cooling air channel which extends through the interior of the motor housing (19).

12. Impeller machine according to Claim 11, characterized in that an outlet opening (35) of the cooling air channel opens out in a region of the annular space in which a negative pressure is present during operation of the impeller machine.

13. Impeller machine according to any one of Claims 1 to 10, characterized in that the interior of the motor housing (19) is sealed dust-tightly and / or water-tightly.

14. Impeller machine according to any one of Claims 1 to 13, characterized by an aero stator (20) which holds the motor housing (19) relative to the impeller housing (15), wherein a cable is routed inside the aero stator.