Noise-optimized system for driving a centrifugal pump

Abstract

The invention relates to a system (1) for driving a centrifugal pump (2), wherein the system (1) has at least one cooling arrangement (6, 23) comprising cooling fins (7). The cooling fins (7) are arranged in rows at a distance from one another. At least some of the cooling fins (7) have a lower region (11) with a height (H) and an upper region (12) which forms a height profile (13), wherein the upper region (13) has recesses (14) for forming the height profile (13). Each recess (14) forms a geometric shape which has a width (B) and a depth (T).

Description

[0001] The invention relates to a system for driving a centrifugal pump, wherein the electric motor has at least one cooling arrangement comprising cooling fins, wherein the cooling fins are arranged in rows at a distance from one another.

[0002] A centrifugal pump typically includes a drive system, usually comprising one or more electric motors and power electronic devices for speed control via frequency conversion. The electric motors and the associated motor electronics, in particular, require adequate cooling during operation.

[0003] An electric motor consists of a rotor that is connected to the motor shaft in a rotationally fixed manner, a stator with a wound stator package, a stator housing with cooling fins on the outside, bearing shields on both sides with rolling or plain bearings and, optionally, a fan wheel that is connected to the shaft on the shaft end opposite the drive side in a rotationally fixed manner and can be enclosed by a fan cover that is firmly connected to the stator housing.

[0004] DE 10 2021 000 933 A1 discloses a pump comprising a drive motor, at least one electronics housing and at least one heat sink for dissipating heat from the electronics housing, wherein an intermediate piece for thermally decoupling the heat sink from the motor housing is inserted between the heat sink and the motor housing of the drive motor.

[0005] DE 10 2021 108 359 A1 describes an electric motor for driving a centrifugal pump with a cooling arrangement. The cooling arrangement comprises a fan impeller and a hood, with the hood enclosing a space. Guide elements are arranged within the space.

[0006] DE 10 2021 005 031 A1 discloses a heating circulation pump with at least one electronics housing for the pump electronics, wherein the electronics housing is composed of at least two housing parts with an integrated heat sink and at least one sealing element is inserted in the connecting gap of the at least two housing parts.

[0007] Centrifugal pumps, and thus also the electric motors used to drive them, are sometimes used in noise-sensitive areas, such as hospitals, kindergartens, schools, and even private households. One area of application is the conveyance of fluids in heating or cooling systems. It is desirable and desirable to keep the noise and sound pressure levels of the motors and pumps as low as possible.

[0008] Some pump series already feature centrifugal pumps optimized for noise reduction. To achieve even lower sound pressure levels, the components adjacent to the pump, such as the cooling system, must also be optimized. At certain frequencies, for example, the ends of the cooling fins of a cooling system can move and emit corresponding sound waves.

[0009] The structure of the cooling fins of a cooling system itself can be susceptible to resonance phenomena, especially if they are not securely mounted or sufficiently damped. If the frequency of the exciting forces from the motor, power electronics, or pump coincides with the natural resonant frequency of the cooling fins, the vibrations are amplified, which can lead to loud noises.

[0010] Additionally, cooling systems are equipped with fans that pull air through the cooling fins to dissipate heat. If these fans are not well balanced or if they show signs of wear, they can generate additional vibrations. Vibrations can also be caused by the uneven rotation of the fan blades and can be perceived as a humming or buzzing sound.

[0011] The object of the invention is to provide a system for driving a centrifugal pump with a cooling arrangement that can be operated with particularly low noise and at a low sound pressure level. The cooling arrangement should be able to reliably dissipate the heat generated during system operation and when pumping hot fluids. Furthermore, the cooling arrangement should be characterized by a compact design. The cooling arrangement should be simple and cost-effective to implement.

[0012] This object is achieved according to the invention by a system for driving a centrifugal pump according to the features of claim 1. Preferred variants can be found in the independent main claims, the subclaims, the description and the drawings.

[0013] According to the invention, at least some of the cooling fins have a lower region with a height and an upper region which forms a height profile for noise reduction, wherein the upper region has recesses for forming the height profile and each recess forms a geometric shape which has a width and a depth.

[0014] For example, the system consists of an electric motor and power electronics to drive a centrifugal pump.

[0015] The cooling arrangement can, for example, be arranged between the pump housing of the centrifugal pump and the electric motor.

[0016] In a further variant of the invention, the cooling arrangement can be arranged between the electric motor and a box or power electronics box for controlling the electric motor.

[0017] The cooling arrangement according to the invention has a plurality of cooling fins. For example, the cooling fins are arranged in rows spaced apart from one another.

[0018] Preferably, the cooling fins are aligned and arranged parallel to each other.

[0019] For example, the cooling fins are designed as flat cuboids standing on a base plate.

[0020] The base plate is made of a heat-conducting material, for example, and preferably has contact with the electric motor and / or the power electronics.

[0021] In a variant of the invention, the base plate has a height that corresponds to the thickness of the cooling fins.

[0022] The lower area of the cooling fins is, for example, more than 60%, preferably more than 70%, in particular more than 80% of the total height of the cooling fin.

[0023] The upper area of the cooling fins is, for example, less than 40%, preferably less than 30%, in particular less than 20%, of the total height of the cooling fin.

[0024] For example, the upper region is more than 10%, preferably more than 15%, in particular more than 20%, and / or less than 50%, preferably less than 40%, in particular less than 30%, of the height of the lower region.

[0025] In a variant of the invention, the spacing of the cooling fins is more than three times the thickness, preferably more than four times the thickness, in particular more than five times the thickness, and / or is less than eight times the thickness, preferably less than seven times the thickness, in particular less than six times the thickness, of the cooling fins.

[0026] For example, each cooling fin tapers from the bottom to the top. This means that the thickness decreases over the entire height of the cooling fin. This can be advantageous for molding cast cooling assemblies, while simultaneously reducing vibration of the cooling fins. This is particularly beneficial for reducing the noise of the electric motor during operation of the centrifugal pump.

[0027] According to the invention, the upper region of the cooling fin has a height profile. A height profile typically shows the variation in height over a length or the course of a section; in the case of a cooling arrangement, it shows the length of the cooling fin.

[0028] The height profile is designed, for example, for passive noise reduction of the electric motor driving the centrifugal pump. The design of the height profile reduces the vibrations of the cooling fins or the vibrations of the cooling fins relative to each other and / or the sound pressure level caused by the vibrations of the cooling fins.

[0029] This can be achieved, for example, by means of recesses in the upper area of the cooling fins. The recesses of the respective cooling fins are arranged offset from one another, within a row and / or to the next row, so that when the cooling fins vibrate relative to one another, the counterpart is at least partially missing when generating sound pressure, thus achieving passive noise reduction.

[0030] For example, a recess has a depth and a width.

[0031] In a variant of the invention, the depths and widths of the recesses can be identical for all recesses.

[0032] In another variant, the depths and widths of the recesses are different for each recess.

[0033] The arrangement of the recesses, for example, forms the height profile of the upper area of the cooling fin, which can achieve passive noise reduction.

[0034] The height of the recess may, for example, be more than 50%, preferably more than 70%, in particular more than 90%, of the height of the upper region.

[0035] In a variant of the invention, the width of the recess corresponds to the distance between two recesses.

[0036] In a further variant of the invention, the width of the recess is more than 1.5 times, in particular more than 2 times, in particular more than 2.5 times, the distance between two recesses.

[0037] For example, more than three, preferably more than five, in particular more than seven, recesses are arranged in a cooling fin of the cooling arrangement.

[0038] For example, the height profile is periodically formed.

[0039] The word "periodic" refers specifically to the recesses that form the elevation profile, which are arranged at regular intervals or periods, or whose arrangement is repeated. The recesses that form the elevation profile are arranged at intervals or cycles.

[0040] In a variant of the invention, the height profile of all cooling fins of the cooling arrangement has the same geometric shape.

[0041] In a further variant of the invention, the height profile of every second cooling fin of the cooling arrangement has the same geometric shape, wherein the two shapes are arranged alternately to one another.

[0042] For example, at least one height profile of the cooling arrangement is wave-shaped and / or rectangular and / or triangular and / or trapezoidal and / or sawtooth-shaped.

[0043] In a variant of the invention, the height profiles of adjacent cooling fins are designed to be phase-shifted relative to one another, wherein preferably height profiles of immediately adjacent cooling fins are designed to be phase-shifted relative to one another.

[0044] Each of the described designs, and especially the combination of the described designs, can reduce the vibrations of the cooling fins. For example, sound waves cancel each other out due to the design of the cooling fins. The so-called air pumping in the room caused by the movement of the cooling fins relative to each other is significantly reduced or even completely prevented, preventing sound and thus noise.

[0045] For example, the phases of the height profiles of adjacent cooling fins are more than π8, preferably by more than π6, in particular by more than π4, and / or less than 13 π8, preferably less than 11 π8, in particular by less than 9 π8, The phase shift advantageously realizes the passive noise reduction of the cooling arrangement.

[0046] In one variant, the depth and width of the geometric shape are identical in all recesses.

[0047] In an alternative variant, the cooling fins are at least partially designed as a corrugated plate standing on a base plate. This design is advantageous for passive noise reduction of the cooling arrangement.

[0048] For example, the cooling arrangement is integrated as part of the electric motor housing.

[0049] In one variant, the cooling arrangement is formed in one piece with the electric motor housing.

[0050] In an alternative variant, the cooling arrangement is mounted flush with the electric motor housing.

[0051] In a further variant of the invention, the cooling arrangement is connected to a power electronics system. For example, the components of the power electronics can be connected flush with the cooling arrangement.

[0052] In an alternative variant, the cooling arrangement is formed as a single piece with the power electronics box.

[0053] In a variant of the invention, the cooling arrangement is formed in one piece.

[0054] In an alternative variant of the invention, the base plate of the cooling arrangement is cylindrical. For example, the cooling fins are arranged in a star shape on the base plate and / or in rows in a star shape and / or parallel to one another. This design is advantageous, for example, in a one-piece design of the cooling arrangement with the electric motor housing.

[0055] In one variant of the invention, the rows of cooling fins on the cylindrical base plate are straight. For example, the rows are aligned parallel to each other.

[0056] In an alternative variant, the rows of cooling fins have a sinusoidal shape.

[0057] For example, the cooling arrangement can also include a fan for active cooling. The design of the height profile of the cooling fins advantageously reduces noise generation, allowing the electric motor to drive a centrifugal pump even in noise-sensitive areas.

[0058] In one embodiment of the invention, the cooling arrangement, in particular the one-piece structure of the cooling arrangement, is produced by a method in which the cooling arrangement with the cooling fins including the recesses for passive noise reduction is produced by selectively exposing energetic radiation to powder layers applied in layers.

[0059] Selective laser melting (SLM) is an additive manufacturing process used to produce the cooling fins of the cooling assembly as a one-piece structure from metal powder, particularly aluminum or copper powder. It is a form of 3D printing that uses a high-power laser to selectively melt the powder and build up the base plate and cooling fins layer by layer.

[0060] The base plate and fins of the cooling assembly are built layer by layer by applying a thin layer of powder to a build platform. The laser beam is then directed at the selected areas, where it melts the metal powder and bonds it into a solid layer. A new layer is then applied, and the process is repeated until the cooling assembly is complete.

[0061] Preferably, a high-power laser, typically a fiber laser or a CO2 laser, is used. The laser beam is precisely controlled to melt and fuse the metal powder. The laser parameters such as power, intensity, and speed are adjusted according to the requirements of the process and the selected material, especially a metallic material. For example, the laser parameters can also be partially adjusted to achieve defined and desired microstructures.

[0062] After generative manufacturing, the cooling arrangement may be post-processed, for example to achieve flat surfaces of the cooling fins and / or a smooth shape of the height profile.

[0063] In an alternative variant of the invention, the cooling arrangement can also be manufactured using a casting process.

[0064] For example, the cooling arrangement is made entirely of the same and identical material.

[0065] In an alternative variant of the invention, the cooling arrangement comprises a structure for noise reduction, wherein the structure has, for example, web-like connections.

[0066] The structure includes at least one web-like connection and can consist of a network of interconnected web-like connections that position the free ends of the cooling fins relative to one another. The structure can, for example, be plugged in. In systems already in operation, the structure can also be plugged in later. Alternatively, the structure can be permanently connected to the cooling arrangement as a single piece. Furthermore, the structure itself can be formed as a single piece or consist of unconnected individual elements.

[0067] In one variant of the invention, the structure is designed as a separate part that is plugged onto the cooling fins of the cooling assembly. This design variant is ideal for reducing the noise of existing electric motors already in use for driving centrifugal pumps, whereby the structure can be easily plugged onto the cooling assembly at a later date.

[0068] In a further variant of the invention, the structure is integrated into the cooling arrangement. This is not a loose, attached design variant, but rather a permanently integrated and non-detachable structural variant.

[0069] In a special variant of the invention, the structure is formed from unconnected, individual elements. The individual elements are distributed, for example, throughout the cooling arrangement in such a way that they prevent the cooling fins from vibrating at their free ends for passive noise reduction. The elements can extend, for example, from one cooling fin to the adjacent cooling fin or even across multiple cooling fins.

[0070] According to the invention, the system is used to drive a centrifugal pump with the cooling arrangement while reducing noise in very noise-sensitive application fields.

[0071] Further features and advantages of the invention will become apparent from the description of embodiments with reference to the drawings and from the drawings themselves.

[0072] It shows: Fig. 1 an exemplary design of the system for driving a centrifugal pump, Fig. 2 an exemplary embodiment of the cooling arrangement, which is arranged between the power electronics box and the electric motor, Fig. 3 another variant of the cooling arrangement, Fig. 4 a design of the cooling fins with recesses, Fig. 5 another version of the cooling fins with recesses, Fig. 6 another version of the cooling fins with recesses, Fig. 7 another version of the cooling fins with recesses, Fig. 8 an alternative design of the cooling fins with recesses, Fig. 9 a design of the cooling fins with a sinusoidal height profile, Fig. 10 an embodiment of the cooling arrangement with wave-shaped cooling fins, Fig. 11 another variant of the system, Fig. 12 an embodiment of the cylindrical cooling arrangement.

[0073] Fig. 1 shows an exemplary embodiment of the system 1 for driving a centrifugal pump 2, consisting of an electric motor 25 and power electronics 24. The modern high-efficiency pump has a suction nozzle 3 and a pressure nozzle 4, via which the centrifugal pump 2 is integrated into a piping system.

[0074] In the illustrated embodiment, the electric motor 25 is designed as a canned motor. The canned motor is a special type of wet-running motor in which the stator winding is protected from the conveying medium by a cylindrical, preferably thin-walled tube in the air gap of the machine.

[0075] The power electronics 24 of system 1 is located in the electronics box 5. The cooling arrangement 6 is positioned at the bottom of the electronics box 5. The housing of the electric motor 25 also has a cooling arrangement 23.

[0076] Fig. 2 and Fig. 3 shows a cooling arrangement 6 that can be attached to the underside of the electronics box 5. The cooling arrangement 6 has fourteen cooling fins 7 that are spaced at an equal distance. The cooling fins 7 extend from a base plate 8 and taper away from the base plate 8. The thickness of the cooling fin 7 decreases over its height.

[0077] The cooling arrangement 6 has a round area 9 with shortened cooling fins 7, within which two drill sleeves 10 are arranged for fastening to the electric motor 25.

[0078] The cooling fins 7 have a lower region 11 with a height H and an upper region 12 with a height h, which forms a height profile 13 for noise reduction. The upper region 12 has recesses 14 for forming the height profile 13. Each recess 14 forms a geometric shape.

[0079] The elevation profile 13 in Fig. 2 is formed with the recesses 14 in a periodic and rectangular shape.

[0080] The elevation profile 13 in Fig. 3 is periodic and wave-shaped, with the recess 14 being designed as a corresponding wave cutout.

[0081] Fig. 4 to 8 show exemplary detailed sections of different cooling arrangements 6. Each cooling arrangement 6 has a plurality of cooling fins 7 spaced apart at a distance. The distance between the cooling fins 7 is four times the thickness of a cooling fin 7.

[0082] The cooling fins 7 are aligned and arranged parallel to each other. The cooling fins 7 are designed as flat cuboids standing on a base plate 8.

[0083] The cooling fins 7 have a lower region 11 and an upper region 12, which form a height profile 13 for noise reduction. The height of the lower region 11 is 85% of the total height of the cooling fin 7, and the upper region 12 is 15% of the total height of the cooling fin 7.

[0084] The upper region 12 has recesses 14 for forming the height profile 13 and each recess 14 forms a geometric shape having a width B and a depth T.

[0085] In Fig. 4 shows a variant in which each recess 14 has a different depth T and width B. This results in an inhomogeneous height profile 13, with oppositely arranged height profiles 13 achieving a very reduced sound pressure level and thus effectively reducing the noise generated during operation of the system 1.

[0086] Fig. Figure 5 discloses a variant in which each recess 14 has exactly the same depth T and width B. The height profile 13 is thus rectangular and homogeneous. The recesses 14 of a cooling fin 7 are partially offset from the recesses 14 of the nearest cooling fin 7. As a result, the height profiles 13 of immediately adjacent cooling fins 7 are π2 formed out of phase with each other.

[0087] In the version in Fig. 6, the height profiles 13 of immediately adjacent cooling fins 7 are phase-shifted by π. This phase shift advantageously realizes the passive noise reduction of the cooling arrangement 6.

[0088] In Fig. 7 shows a variant in which the height profile 13 has trapezoidal recesses 14 and in which the height profiles 13 of immediately adjacent cooling fins 7 are designed to be phase-shifted by π relative to one another.

[0089] Fig. 8 shows a variant of the cooling arrangement 6 with a triangular height profile 13 of the cooling fins 7.

[0090] Fig. 9 shows an embodiment of the cooling fins 7 with a sinusoidal height profile 13. The height profiles 13 of immediately adjacent cooling fins 7 are phase-shifted by π.

[0091] Fig. 10 shows a variant of the cooling arrangement 6, in which the cooling fins 7 are arranged in a wave shape on the base plate 8.

[0092] Fig. 11 shows a further exemplary embodiment of the system 1 for driving a centrifugal pump 2, consisting of an electric motor 25 and power electronics 24. The centrifugal pump 2 has a suction nozzle 3 and a pressure nozzle 4, via which the centrifugal pump 2 is integrated into a piping system.

[0093] In the illustrated embodiment, the electric motor 25 is designed as a motor flanged via a lantern. The power electronics 24 of the electric motor 25 are arranged in the box 5, which is positioned on the electric motor 25 at a distance from it by a cooling arrangement 6. The housing of the electric motor 25 also has a cooling arrangement 23.

[0094] In Fig. Figure 12 shows a variant of a cylindrical cooling arrangement 23. The cooling arrangement 23 has twelve cooling fins 7, which are spaced at an equal distance.

[0095] The upper region 12 of the cooling fins 7 each has recesses 14 to form the height profile 13 and each recess 14 forms a geometric shape having a width B and a depth T.

[0096] In the cylindrical design variant shown, each recess 14 has exactly the same depth T and width B. The height profile 13 is thus rectangular and homogeneous. The height profiles 13 of immediately adjacent cooling fins 7 are phase-shifted by π from each other. This phase shift advantageously realizes the passive noise reduction of the cooling arrangement 23. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 000 933 A1

[0004] DE 10 2021 108 359 A1

[0005] DE 10 2021 005 031 A1

[0006]

Claims

[1] System (1) for driving a centrifugal pump (2), wherein the system (1) has at least one cooling arrangement (6, 23) comprising cooling fins (7), wherein the cooling fins (7) are arranged in rows at a distance from one another, characterized by that at least some of the cooling fins (7) have a lower region (11) with a height (H) and an upper region (12) which forms a height profile (13) for noise reduction, wherein the upper region (12) has recesses (14) for forming the height profile (13) and each recess (14) forms a geometric shape which has a width (B) and a depth (T). [2] System according to claim 1, characterized by that the height profile (13) is periodic. [3] System according to claim 1 or 2, characterized by that the height profile (13) has the same geometric shape for all cooling fins (7) of the cooling arrangement (6, 23). [4] System according to one of claims 1 to 3, characterized bythat at least one height profile (13) is wave-shaped and / or rectangular and / or triangular and / or trapezoidal and / or sawtooth-shaped. [5] System according to one of claims 1 to 4, characterized by that height profiles (13) of adjacent cooling fins (7) are designed to be phase-shifted relative to one another, wherein height profiles (13) of immediately adjacent cooling fins (7) are preferably designed to be phase-shifted relative to one another. [6] System according to claim 5, characterized by that the phases of the height profiles (13) of adjacent cooling fins (7) are more than π8, preferably by more than π6, in particular by more than π4, and / or less than 13π8, preferably less than 11π6, in particular by less than 9 π8, are shifted. [7] System according to one of claims 1 to 6, characterized bythat the depth (T) and the width (B) of the geometric shape are identical in all recesses (14). [8] System according to one of claims 1 to 7, characterized by that the upper region (12) is more than 10%, preferably more than 15%, in particular more than 20%, and / or less than 50%, preferably less than 40%, in particular less than 30%, of the height (H) of the lower region (11). [9] System according to one of claims 1 to 8, characterized by that the cooling fins (7) are designed as flat cuboids standing on a base plate (8). [10] System according to one of claims 1 to 9, characterized by that the cooling fins (7) are at least partially designed as a corrugated plate standing on a base plate (8). [11] System according to one of claims 1 to 10, characterized by that the cooling arrangement (23) is integrated as part of the housing of the electric motor 25. [12] System according to one of claims 1 to 11, characterized by that the cooling arrangement (6, 23) is connected to a power electronics system. [13] System according to one of claims 1 to 12, characterized by that the cooling arrangement (6, 23) is formed in one piece. [14] Use of a system (1) to drive a centrifugal pump (2) while reducing noise in very noise-sensitive application areas.

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