How to adjust the fan

Abstract

The fan comprises two impellers, one positioned abreast and the other in the direction of through-flow, and either sharing a common drive or each having its own drive. The outer diameter of one of the two impellers is smaller than the outer diameter of the other. This method is used to adjust the fan.

Description

Technical Field

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[0001] The present invention relates to a fan having two impellers. In this regard, reference may be made to Patent Document 1 as a pure example. Also, such a fan is known in practical use. Furthermore, the present invention relates to a method for adjusting such a fan.

Background Art

[0002] A general fan, particularly a fan in which two or more impellers are arranged one behind the other, has a problem of generating noise during operation. Such a fan emits a very large amount of noise. Furthermore, in such a fan, when the throttle rotation speed rises or falls beyond the "design point", that is, beyond the maximum efficiency point, the efficiency drops sharply. This is because the operable variable is only the rotation speed of the fan. Normally, this configuration is suitable for setting the required air flow rate, but is not suitable for more extensive optimization of fan operation.

[0003] In a fan having one impeller, the rotational speed that causes a problem in terms of vibration can be reduced or avoided by shifting it upward or downward from the required air flow rate. So-called reachability cannot affect separately from the air flow rate during operation. Therefore, the uniformity when introducing an air flow into a downstream machine such as a heat exchanger cannot affect separately from the air flow rate of the fan.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] The problem that this invention aims to solve is to configure a general-purpose fan to operate efficiently across a wide range of throttle conditions, providing high output while simultaneously achieving the lowest possible noise level. Furthermore, while operating at a predetermined output value, other parameters can be optimized according to the requirements of a specific application. Furthermore, this fan is intended to differentiate the product from those of competitors. The same applies to the methods. [Means for solving the problem]

[0006] The above-mentioned problems are solved by the features of claim 1. In other words, this fan has two impellers that are positioned one behind the other in the direction of the through-flow. These two impellers may have a common drive system, or they may each have an independent drive system, in which case the drive system is an electric drive system. The outer diameter of one impeller is smaller than the outer diameter of the other. In relation to the method of the present invention, the above-mentioned problems are solved by independent claim 11.

[0007] Preferably, the outer diameter of the small-diameter impeller is at least 20% smaller than the outer diameter of the large-diameter impeller. This means that the outer diameter of one small-diameter impeller is significantly smaller than the outer diameter of the other large-diameter impeller.

[0008] A non-rotating guide device may be provided between the two small-diameter impellers and the large-diameter impeller. This guide device may include guide vanes. This guide device is positioned in the flow region between two small-diameter impellers and a large-diameter impeller, and has a bearing function for the drive unit. This configuration separates multiple flow regions from one another.

[0009] Furthermore, this guide device includes an outer through-flow region far from the axis and an inner through-flow region close to the axis, and these through-flow regions are separated from each other by an intermediate ring. Furthermore, small-diameter impellers are advantageous even when allocated to the inner through-flow region close to the axis.

[0010] Large-diameter impellers are even more advantageous if they are radial or diagonal flow designs. The small-diameter impeller may be located within the area of ​​the large-diameter impeller or within the suction nozzle, that is, within the inflow area of ​​the large-diameter impeller. The small-diameter impeller is then attached to a structure located on the inlet side of the small-diameter impeller, for example, to an inlet grate.

[0011] Furthermore, it is conceivable that the two small-diameter impellers and the large-diameter impeller could rotate in the same direction or in opposite directions.

[0012] The method of the present invention solves the problem by the feature of claim 11, which optimizes the fan operation by setting / modifying the rotational speed of at least one of the two impellers.

[0013] If the drive mechanisms for the two impellers are independent of each other, the rotational speeds of the two impellers may be set or adjusted independently of each other.

[0014] Preferably, the rotational speeds of the two impellers are synchronized with each other and adjustable according to the operating point.

[0015] Fan operation may be optimized by setting the rotational speed of a second impeller, which includes an EC drive unit for one of the two impellers.

[0016] The rotational speeds of the two impellers can be set or adjusted using a special regulating device and are advantageously carried out using artificial intelligence methods, machine learning methods, and / or conventional control algorithms for a desired air flow rate and, optionally, at least one further target variable, such as the overall efficiency.

[0017] Further parameters to be optimized may include vibration values, axial thrust, efficiency, acoustic characteristics, psychoacoustic aspects, far - reachingness, flow patterns for heat exchangers, etc. Thus, the fan according to the invention forms a platform for implementing a quasi - intelligent fan. Such a fan itself is a turbomachine, but the invention is also applicable to other turbomachines.

[0018] There are various options for developing the present invention. For its implementation, refer to the claims dependent on claim 1 for the fan and the method - related claims dependent on claim 11 for the method, as well as the following description of the embodiments of the invention based on the drawings. In conjunction with the embodiments of the invention based on the drawings, the development aspects of the invention will also be outlined.

Brief Description of the Drawings

[0019] [Figure 1] It is a perspective view of a fan which is an embodiment of the invention having a large - diameter impeller and a small - diameter impeller, seen from the outflow side, with a bearing guide device arranged between the two impellers. [Figure 2] It is an axial plan view of the fan of FIG. 1 having two impellers with different diameters, seen from the outflow side. [Figure 3] It is a cross - sectional side view in a plane passing through the axis of the fan of FIGS. 1 and 2 having two impellers with different diameters, and the flow during fan operation flows substantially from left to right. [Figure 4]Figure 3 shows a cross-sectional side view in a plane passing through the axis, similar to that of a further embodiment of a fan having two impellers of different diameters, in which the outer diameter expansion wall on the outer housing contour protrudes axially in the outflow direction more than the smaller diameter impeller. [Figure 5] Figure 4 is a perspective view of the embodiment shown from the outflow side, where the intermediate ring of the guide unit and the outer wall of the small-diameter impeller are manufactured as a single unit. [Modes for carrying out the invention]

[0020] Figure 1 is a perspective view of an axial flow design fan 1, which is an embodiment of the present invention, as seen from the outlet side. First, this fan 1 is equipped with a large-diameter impeller 19A and a small-diameter impeller 19B. In particular, a rotary bearing guide device including bearing guide vanes 11 is positioned between these two large-diameter impellers 19A and small-diameter impellers 19B.

[0021] The bearing guide device is integrated into the guide housing 2, which, in addition to the bearing guide vanes 11, also has an outer housing contour that includes an inlet nozzle 9 (see also Figure 3), an operating area 29A for the large-diameter impeller 19A, and a diameter expansion area 10. During the operation of fan 1, the fluid medium is drawn into fan 1 through the inlet nozzle 9, first through the operating region 29A of the large-diameter impeller 19A within the guide housing 2, then through the diameter expansion region 10, and then discharged again from fan 1 diagonally to the left and forward in the diagram of Figure 1. The rotation of the two operating large-diameter impellers 19A and small-diameter impeller 19B transfers energy between the large-diameter impellers 19A and 19B and the fluid medium, thereby maintaining the flow.

[0022] The bearing guide device or guide housing 2 is designed to have an intermediate ring 5 manufactured integrally with the guide housing 2, and an outer support vane 3 also manufactured integrally with the guide housing 2. The guide vane 11 is designed as an inner guide vane and extends radially or spanwise from the hub ring 4, which is manufactured integrally with it, to the intermediate ring 5. The intermediate ring 5 extends in the circumferential direction and is positioned between the radially inward hub ring 4 and the outer housing contour. The outer housing contour is formed by the inlet nozzle 9, the operating area 29A, and the diameter expansion area 10. The outer support vane 3 extends between the intermediate ring 5 and the outer housing contour. Therefore, the outer support vane 3, the intermediate ring 5, and the guide vane 11 together are responsible for the bearing connection between the hub ring 4 and the outer housing contour.

[0023] The two large-diameter impellers 19A and small-diameter impellers 19B are directly or indirectly attached to the hub ring 4, along with their respective large drive units 34A and small drive units 34b. The guide housing 2, and by extension the entire fan 1, can be fixed to the upper fluid system, either by the inlet-side fixing means 20 in the area of ​​the outer housing contour, such as the area of ​​the inlet nozzle 9, or by the outlet-side fixing means 21 in the diameter-expanded area 10.

[0024] To ensure that the protective grate does not protrude axially from the guide housing 2, a fixing means 25 for the protective grate is positioned on the outflow side of the guide housing 2 so that the protective grate can be properly attached by screwing it axially into the guide housing 2 in a recessed state.

[0025] The intermediate ring 5 separates the radial inner through-flow region 7 from the radial outer through-flow region 6, and these inner and outer through-flow regions 7 and 6 extend within the outer housing contour defined by the inlet nozzle 9, the operating region 29A of the large-diameter impeller 19A, and the diameter-expanding wall 10. The entire conveyor flow through fan 1, and the entire conveyor flow through the region of the large-diameter impeller 19A and its blades 22A, are divided to some extent into an inner permeable flow region 7 and an outer permeable flow region 6. However, the small-diameter impeller 19B almost exclusively covers the area of ​​the inner through-flow region 7 in the radial or spanner direction, and has a significantly smaller diameter than the large-diameter impeller 19A, for example, a diameter of less than 75% of the diameter of the large-diameter impeller 19A.

[0026] To obtain a good efficiency value, the small-diameter impeller 19B operates together with its blades 22B within a region defined radially or spanwise by the outer wall 8. In this case, the outer wall 8 is simply designed to extend to the outflow side edge 12 as an extension of the intermediate ring 5 which is integrally attached to the guide housing 2. Furthermore, since this outer wall 8 does not rotate, a gap is formed between the small-diameter impeller 19B and the outer wall 8 of this small-diameter impeller 19B. In this regard, it is advantageous to provide winglets 38B on the outer ends of the blades 22B of the small-diameter impeller 19B in order to minimize noise generation and maximize efficiency.

[0027] Either almost all of the carrier flow passes through the large-diameter impeller 19A, or the large-diameter impeller 19A is powered while only a small portion of the carrier flow passes through the small-diameter impeller 19B, or the small-diameter impeller 19B interacts with the carrier flow only through power transmission. This is particularly noticeable when the outer diameter of the small-diameter impeller 19B is small. The overall efficiency and pressure stability of fan 1 can be significantly improved by influencing the flow in the radially inner region of fan 1, that is, by transmitting power. On the other hand, this makes it possible to relatively reduce noise generation in the radially inward region. In other words, the small-diameter impeller 19B and its blades 22B result in relatively low noise generation due to rotor-stator interaction and / or rotor-rotor interaction and / or head gap turbulence noise.

[0028] The non-rotating guide vanes 11, positioned between the two large-diameter impellers 19A and the small-diameter impeller 19B, ensure intermediate flow straightening (eddy flow reduction), and therefore the guide vanes 11 also function as bearings.

[0029] In other embodiments, the intermediate ring 5 is not formed in the guide housing 2, and the guide vane 11 extends continuously from the hub ring 4 to the outer housing contour. In this case, the small-diameter impeller 19B includes a covering that rotates with it, and this covering interconnects the blade ends of the small-diameter impeller 19B, separating the partial flow that flows through the small-diameter impeller 19B from the outer flow that does not flow through the small-diameter impeller 19B when viewed radially or spanwise.

[0030] Furthermore, the large-diameter impeller 19A in Figure 1 rotates in the rotational direction 32A, and the small-diameter impeller 19B rotates in the rotational direction 32B. The rotation directions 32A of the two large-diameter impellers 19A and the rotation direction 32B of the small-diameter impeller 19B are opposite.

[0031] In other embodiments, if the rotation directions 32A of the two large-diameter impellers 19A and the rotation direction 32B of the small-diameter impeller 19B are opposite, the fluid-operated guide vane 11 positioned between the large-diameter impeller 19A and the small-diameter impeller 19B may be omitted. Depending on the embodiment, it is also possible to make the rotation direction 32A of both large-diameter impellers 19A the same as the rotation direction 32B of the small-diameter impeller 19B. By making the rotation direction 32A of the large-diameter impeller 19A and the rotation direction 32B of the small-diameter impeller 19B the same, and by using a fluid-operated guide vane 11, there is an advantage in that the noise level of the fan 1 can be reduced.

[0032] The large-diameter impeller 19A is formed by a hub ring 31A (Figure 3) and a blade 22A fixed to the hub ring 31A, and is fixed to the large drive unit 34A by the hub ring 31A.

[0033] In other embodiments, the large-diameter impeller 19A may also include a covering that interconnects the outer ends of its blades 22A in the circumferential direction.

[0034] The small-diameter impeller 19B is formed by a hub ring 31B and a blade 22B fixed to the hub ring 31B, and is fixed to the small drive unit 34B by the hub ring 31B.

[0035] In other embodiments, the small-diameter impeller 19B may further include a covering that interconnects the outer ends of its blades 22B in the circumferential direction.

[0036] Figure 2 is an axial plan view of fan 1, which has two large-diameter impellers 19A and a small-diameter impeller 19B of different diameters as shown in Figure 1, as seen from the outlet side. In addition to the explanation in Figure 1, the rotation direction 32A of the large-diameter impeller 19A and the different rotation direction 32B of the small-diameter impeller 19B are clearly shown. Furthermore, when viewed from the axial direction, the outer support vane 3 is significantly inclined with respect to the outflow side edge 26A of the vane 22A of the large-diameter impeller 19A. For example, the projection view in Figure 2 shows that it is inclined at an angle exceeding 45° with respect to the outflow side edge 26A of the large-diameter impeller 19A. This configuration is particularly advantageous in reducing the generation of blade passing noise in the radially outer region where rotational speeds are high.

[0037] In the radially inward region, a relatively large number of inner guide vanes 11 face the vanes 22B of the small-diameter impeller 19B. Therefore, in this section, the noise generation frequency when the blades pass becomes higher, which is often advantageous, as the noise intensity is lower.

[0038] The outflow side edge 26A of the blade 22A of the large-diameter impeller 19A is designed with an uneven surface to reduce trailing edge noise.

[0039] The outflow side edge 26B of the blade 22B of the small-diameter impeller 19B is not uneven. The reason for this is that the small-diameter impeller 19B has less impact on the overall noise generation of fan 1 than the large-diameter impeller 19A. In other embodiments, the outlet side edge 26B of the small-diameter impeller 19B and / or its blades 22B is uneven.

[0040] The hub ring 31B of the small-diameter impeller 19B has a mounting opening 24 formed therein, which facilitates the installation of a motor 34A (not shown here) along with a bearing unit integrated into the guide housing 2. In a fan 1 equipped with two impellers of different diameters, a large-diameter impeller 19A and a small-diameter impeller 19B, it is advantageous to provide such a mounting opening 24 or similar on one of the impellers, usually located in the hub area, and these mounting openings 24 may be closed after the fan 1 is installed, for example, to prevent noise during operation, if necessary.

[0041] Figure 3 is a side cross-sectional view in a plane passing through the axis of fan 1 in Figures 1 and 2. Fan 1 is equipped with two large-diameter impellers 19A and small-diameter impellers 19B of different diameters. During the operation of fan 1, in this figure, the flow flows roughly from left to right through fan 1 and / or its guide housing 2 within the outer housing contour, through the region within the inlet nozzle 9, then through the cylindrical operating region 29A of the outer housing contour (which also forms the region of the large diameter impeller 19A), and finally through the region of the outer diameter expansion wall 10.

[0042] After passing through the large-diameter impeller 19A, the flow is substantially divided into two permeable flow regions separated from each other by a wall, namely, an inner permeable flow region 7 and an outer permeable flow region 6.

[0043] The wall separating the inner through-flow region 7 and the outer through-flow region 6 from each other is an intermediate wall, which is integrated into the entire guide housing 2 and forms a guide device including the outer wall 8 of the small-diameter impeller 19B and the guide vanes 11, as well as the intermediate ring 5 of the guide housing 2. After passing through the large-diameter impeller 19A, the flow flows over the inlet side edge 23 of the intermediate ring 5, where it is divided into two through-flow regions: an inner through-flow region 7 and an outer through-flow region 6.

[0044] The through-flow that flows through the inner through-flow region 7 also passes through the small-diameter impeller 19B, causing the small-diameter impeller 19B to rotate, and thus power is transmitted to the small-diameter impeller 19B as well. Power transmission is possible in both directions, and in all cases, power is transmitted from the small-diameter impeller 19B to the through-flow (which can be allocated to the inner through-flow region 7). Since the flow through the outer through-flow region 6 does not substantially pass through the small-diameter impeller 19B, no additional noise is generated in this region due to interaction with the rotating blades.

[0045] Furthermore, the inner through-flow region 7 and the outer through-flow region 6 are separated by a rotating ring integrated with the small-diameter impeller 19B and connecting the outer blade ends, and no non-rotating partition wall is provided. This is true when the bearing guide vane 11 is designed to be continuous from the hub ring 4 to the outer housing contour. In all cases, only a portion of the total throughflow of fan 1 passes through the inner throughflow region 7, and consequently the small-diameter impeller 19B, and the inner throughflow region 7 and the outer throughflow region 6 are separated by a partition wall. Furthermore, in the flow direction, it is also conceivable to place the small-diameter impeller 19B upstream of the large-diameter impeller 19A. In this embodiment, the entire flow of the fan 1 is divided into two through-flow regions upstream of the large-diameter impeller 19A, and the flow is configured to merge after passing through the two through-flow regions and then pass through the large-diameter impeller 19A. The partition wall between the inner through-flow region 7 and the outer through-flow region 6 is either rotary and integrated with a small-diameter impeller 19B, or non-rotating and integrated with a bearing device including guide vanes 11.

[0046] In particular, if the large-diameter impeller 19A is a radial fan design or a mixed-flow fan design, the small-diameter impeller 19B may be positioned in front of the large-diameter impeller 19A or in the area of ​​the suction nozzle (inlet region). The small-diameter impeller 19B may be designed as an axial impeller or a diagonal flow impeller that is slightly axially oriented.

[0047] The division of the flow into the inner through-flow region 7 and the outer through-flow region 6 continues in the region of the large-diameter impeller 19A, in the form of a rotating partition wall integrated with the large-diameter impeller 19A, which interconnects the blades in the spanwise direction between the hub ring 31A of the large-diameter impeller 19A and the outer housing contour.

[0048] The large-diameter impeller 19A may include a circumferential covering that connects the outer ends of the blades. In this case, the outer covering may define the outer housing contour, which may be called the outer flow contour.

[0049] The large-diameter impeller 19A or its hub ring 31A in Figure 3 is connected to the rotating part of the large drive unit 34A by a connecting device 30A and is screwed in place.

[0050] The small-diameter impeller 19B or its hub ring 31B is connected to the rotating part of the small drive unit 34B by a connecting device 30B and is screwed in place. Figure 3 clearly shows the drive systems for the large-diameter impeller 19A and the small-diameter impeller 19B, and more preferably the electric drive system 34A and the compact drive system 34B. The large-diameter impeller 19A and the small-diameter impeller 19B, or their hub rings 31A and 31B, are connected to the rotary connectors of the large drive unit 34A and the small drive unit 34B. The large drive unit 34A and the small drive unit 34B hold the large-diameter impeller 19A and the small-diameter impeller 19B and drive them in the rotational direction 32A and 32B, respectively, thereby transmitting power between the large drive unit 34A and the small drive unit 34B and the large-diameter impeller 19A and the small-diameter impeller 19B.

[0051] A large-diameter impeller 19A typically includes a large drive unit 34A that has higher power output or higher driving torque than a small-diameter impeller 19B, while a small-diameter impeller 19B requires only a small drive unit 34B with lower power output or lower driving torque. The low-power, compact drive unit 34B requires less than 50% of the manufacturing cost (cost or CO2 equivalent) of the large drive unit 34A, resulting in a manufacturing cost that is only slightly higher compared to an equivalent conventional system without the small-diameter impeller 19B and compact drive unit 34B. Despite only a slight increase in manufacturing costs, the power density, efficiency, coverage, and adaptability can be significantly improved compared to conventional fans.

[0052] The first impeller (large-diameter impeller 19A in this embodiment), located on the inflow side, is provided with a curved hub cap 37 that is aerodynamically advantageous, either on its hub ring 31A or in the inflow-side region.

[0053] When the small-diameter impeller 19B is positioned on the inlet side, it is advantageous to provide the small-diameter impeller 19B with an aerodynamically designed hub cap.

[0054] For the large drive unit 34A and the small drive unit 34B, an electric motor with continuously adjustable speed is advantageous, a permanent magnet type EC motor is more advantageous, and an outer rotor structure is even more advantageous. Each motor, including its own control electronic module, may be manufactured completely independently of the others, or it may use a common control electronic module. In all cases, the control electronic module is located near the motor, for example, in the area of ​​the bearing unit, and in the illustrated embodiment, in the area of ​​the hub ring 4 of the bearing guide unit of the guide housing 2.

[0055] Depending on the embodiment, one or more electronic equipment housings 13 may be formed in the areas of the large drive unit 34A and the small drive unit 34B, and control electronic equipment modules may be housed within the electronic equipment housings 13.

[0056] It is particularly advantageous if the rotational speeds of the two large-diameter impellers 19A and small-diameter impellers 19B, or their large drive unit 34A and small drive unit 34B, can be set completely independently of each other. Therefore, depending on the requirements, the rotational speed ratio of the two large-diameter impellers 19A and small-diameter impellers 19B may be optimally set.

[0057] In particular, the two rotation speeds are controlled by a special adjustment device. The control device must guarantee the required flow rate in all forms, but it also has further flexibility (because two rotational speeds can be used as control variables). This can be used, for example, to maximize efficiency, minimize power consumption, minimize noise, minimize vibration, optimize long-distance reach, and optimize through-flow in the heat exchanger near fan 1. In particular, vibration values ​​can be minimized, which means that dangerous rotational speeds of one of the impellers can be automatically avoided.

[0058] The adjustment device used to set the rotational speeds of the two large-diameter impellers 19A and small-diameter impellers 19B can be based on artificial intelligence or machine learning methods, but a simpler, deterministic adjustment method is also very effective.

[0059] The large drive unit 34A and the small drive unit 34B, or the control electronic module, must be electrically and / or electronically connected to the higher-level system. This is because power is transmitted using power cables, and control cables as needed. For this purpose, various devices may be provided, for example, a cable connection part 53 on the control electronic module, a cable feedthrough or opening on the hub head in the area of ​​the hub ring 4, a cable holder 35 on the guide device or bearing support vane 3, and / or a cable feedthrough 36 in the area of ​​the outer housing (see Figure 5).

[0060] Figure 4 is a cross-sectional side view of fan 1, which has two large-diameter impellers 19A and a small-diameter impeller 19B of different diameters, in a plane along the same axis as in Figure 3. In other respects, unlike the fan 1 shown in Figures 1 to 3, an extension 16 of the diameter-expanding wall 10 is further attached to a radially outer flow-limiting member located downstream of the diameter-expanding region 10 integrated with the guide housing 2. This extension 16 is continuously adjacent to the integrated diameter-expanding wall 10 along its inner contour. By extending the radially outer flow limiting member of fan 1 in a radially expanding manner, where the flow path cross-sectional area gradually increases, particularly high efficiency can be advantageously achieved.

[0061] The external flow-restricting member, such as the extension 16 of the diameter-expanding wall 10, protrudes beyond the small-diameter impeller 19B and its outer wall 8 when viewed in the axial outflow direction (right side of the figure), providing further advantages in addition to high efficiency. A flat contact protection grid for contact protection may be formed on the outflow side edge of the diameter expansion attachment 16, without contacting the small diameter impeller 19B, its outer wall 8, or its small drive unit 34B. This configuration makes it easy to stack multiple Fan 1 units during transport.

[0062] The small-diameter impeller 19B, its outer wall 8, or the axially elongated outer diameter expansion portion extending over its small drive unit 34B may also be manufactured integrally with the guide housing 2.

[0063] If the diameter expansion attachment 16 is not manufactured integrally, it may be manufactured from sheet metal, solid plastic material, foamed plastic material, etc.

[0064] In this embodiment, the outer wall 8 of the small-diameter impeller 19B is initially manufactured as a separate annular component and fixed to the guide housing 2 or the intermediate ring 5 of the guide device, and advantageously bonded. For example, to achieve higher efficiency, lower specific noise generation, higher airflow, greater operational flexibility, or optimization of other functions, a small-diameter impeller 19B is retrofitted to an existing conventional fan 1, along with its small drive unit 34B and, if necessary, its outer wall 8.

[0065] Figure 5 is a perspective view from the outlet side of an embodiment of fan 1, similar to Figure 4, which has two large-diameter impellers 19A and a small-diameter impeller 19B of different sizes, and the intermediate ring 5 of the guide unit of the guide housing 2 and the outer wall 8 of the small-diameter impeller 19B are manufactured as a single unit. In this embodiment, a diameter expansion attachment 16 having a somewhat polygonal outer shape is formed at the outlet. This configuration allows multiple fans 1 to be compactly arranged adjacent to each other in a fluid device. The air can flow more uniformly through the heat exchanger, which is connected to the outlet side and has a somewhat polygonal shape.

[0066] Furthermore, the rotational speed ratio of the large-diameter impeller 19A and the small-diameter impeller 19B may be adjusted so that the flow through the heat exchanger connected to the discharge side is as uniform as possible.

[0067] Due to the effect of the small-diameter impeller 19B of fan 1, the air flows more uniformly through the heat exchanger that is opposite the central region of fan 1 and connected to the discharge side, and backflow in this region can be prevented in a simple manner.

[0068] Furthermore, the rotational speed ratio of the large-diameter impeller 19A and the small-diameter impeller 19B may be adjusted to optimize long-distance reach, that is, so that the outflow from fan 1 reaches the space adjacent to the outflow side as far as possible, or so that the conveyed air penetrates the adjacent space as far as possible.

[0069] In particular, the large drive unit 34A and the small drive unit 34B may be designed in the form of a "dual drive unit". In other words, the large drive unit 34A and the small drive unit 34B may include common components such as a common drive unit and / or electronic equipment housing 13, but may have two different drive speeds and connect two large-diameter impellers 19A and small-diameter impellers 19B to different rotors and drive at rotational speeds that are, in principle, independent of each other.

[0070] In other embodiments where manufacturing costs are lower, the rotational speeds of the two large-diameter impellers 19A and small-diameter impellers 19B may be associated in a fixed ratio. This association can be achieved through transmission devices such as gear transmissions and magnetic transmissions.

[0071] In other embodiments where manufacturing costs are lower, the rotational speeds of the two large-diameter impellers 19A and small-diameter impellers 19B may be the same, and the rotational directions 32A and 32B may be the same. In this case, the large-diameter impeller 19A and the small-diameter impeller 19B may be mechanically fixed to the same shaft assembly.

[0072] Depending on the embodiment and operating conditions, the small-diameter impeller 19B may transmit power to its electric drive device like a generator, in which case it functions as a generator.

[0073] For other configurations according to the present invention, please refer to the general portion of the specification and the appended claims to avoid duplication.

[0074] Finally, it should be noted that the above-described embodiments of the present invention are intended solely to illustrate the claimed teachings and are not limited to these embodiments. [Explanation of Symbols]

[0075] 1. Fan (equipped with two impellers of different diameters) 2 ··· Guide Housing (Housing) 3 ···Support vanes 4. Hub ring of bearing unit 5. Intermediate ring of guide unit or diameter expansion element 6...outer flow area 7...Inner flow area 8 ···Outer wall of the small diameter impeller 19B 9 ···Inlet nozzle 10 ···Outer diameter expansion wall 11 ···Inner guide element, guide vane 12...Intermediate ring / Outflow side edge of the outer wall of the small diameter impeller 19B 13. Electronic equipment housing 16 ···Extension of the outer diameter expansion wall 19A...Large diameter impeller 19B... Small diameter impeller 20. Fixing means for the inflow side of the fan to the upper system. 21. ...Method for securing the outflow side of the fan to the higher-level system. 22A... Large diameter impeller blades for 19A 22B... Small diameter impeller blades for 19B 23...Inlet side edge of intermediate ring 5 of guide unit 24 ···Mounting opening on the impeller hub 25. Fixing means for the outlet side protective grid 26A...Outflow side edge of blade 22A of large diameter impeller 19A 26B...Outflow side edge of blade 22B of small diameter impeller 19B 29A... Area of ​​the large-diameter impeller 19A, a nearly cylindrical area of ​​the outer housing contour. 29B... The range of the small-diameter impeller 19B 30A... A method for fixing a large 34A motor to a large diameter impeller of 19A. 30B... A means of fixing the small motor 34B to the small diameter impeller 19B. 31A... Hub ring for large diameter impeller 19A 31B... Hub ring for 19B small diameter impeller 32A...Rotation direction of the large-diameter impeller 19A 32B...Rotation direction of the small diameter impeller 19B 34A... Motor A with a large diameter impeller and 19A drive. 34B... Motor B of the 19B small diameter impeller 35 ···Cable holder on the guide device 36. Cable feedthrough on housing 37 ···Hub cap for impeller 38A...Winglets of 22A blades for large diameter impeller A 38B... Small diameter impeller B blades 22B winglets 53. Cable connections on the motor stator or electronics housing.

Claims

1. A fan comprising two impellers arranged front to back in the direction of through-flow and having a common drive mechanism or each having its own drive mechanism, A fan in which the outer diameter of one of the two impellers is smaller than the outer diameter of the other.

2. The fan according to claim 1, characterized in that the outer diameter of the small-diameter impeller is at least 20% smaller than the outer diameter of the large-diameter impeller.

3. The fan according to claim 1 or 2, characterized in that, in addition to the drive unit, a non-rotating guide device supporting the two impellers, which may include guide vanes, is provided in the flow region between the two impellers.

4. The guide device includes an outer through-flow region far from the axis and an inner through-flow region close to the axis, The outer through-flow region and the inner through-flow region are separated from each other by an intermediate ring. The fan according to claim 3, characterized in that the small-diameter impeller is allocated to the inner through-flow region close to the shaft.

5. The aforementioned large-diameter impeller is designed to be radial or diagonal flow. The small-diameter impeller is located within the region of the large-diameter impeller or within the suction nozzle, that is, within the inflow region of the large-diameter impeller. The fan according to any one of claims 1 to 4, characterized in that the small-diameter impeller is attached, for example, to an inlet grate on a structure located on the inlet side of the small-diameter impeller.

6. A fan according to any one of claims 1 to 5, characterized in that the two impellers rotate in the same direction or in opposite directions.

7. The fan according to any one of claims 1 to 6, characterized in that, when the drive devices for the two impellers are independent of each other, the rotational speeds of the two impellers can be set or adjusted independently of each other.

8. A fan according to any one of claims 1 to 7, characterized in that the rotational speeds of the two impellers are synchronized with each other and adjustable according to the operating point.

9. The fan according to any one of claims 1 to 7, characterized in that the operation of the fan is optimized by setting the rotational speed of the small-diameter impeller, which includes at least an EC drive device, of one or both of the two impellers.

10. The fan according to any one of claims 1 to 9, characterized in that the rotational speeds of the two impellers can be optimally set or adjusted to a desired airflow rate and optionally further target variables of overall efficiency using a special adjustment device employing artificial intelligence, machine learning, and / or conventional control algorithms.

11. A method for adjusting a fan comprising two impellers as described in any one of claims 1 to 10, A method for adjusting a fan, wherein the operation of the fan is optimized by setting / correcting the rotational speed of at least one of the two impellers.

12. A method for adjusting a fan according to claim 11, characterized in that the required output or airflow of the fan is ensured by maximizing the overall efficiency and / or minimizing the overall noise emission and / or the overall vibration and / or vibration.

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