Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D25/00—Pumping installations or systems
  • F04D25/02—Units comprising pumps and their driving means
  • F04D25/06—Units comprising pumps and their driving means the pump being electrically driven
  • F04D25/0606—Units comprising pumps and their driving means the pump being electrically driven the electric motor being specially adapted for integration in the pump
  • F04D25/0613—Units comprising pumps and their driving means the pump being electrically driven the electric motor being specially adapted for integration in the pump the electric motor being of the inside-out type, i.e. the rotor is arranged radially outside a central stator
  • F04D25/062—Details of the bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/08—Sealings
  • F04D29/083—Sealings especially adapted for elastic fluid pumps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/26—Rotors specially for elastic fluids
  • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
  • F04D29/38—Blades
  • F04D29/384—Blades characterised by form
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/40—Casings; Connections of working fluid
  • F04D29/52—Casings; Connections of working fluid for axial pumps
  • F04D29/54—Fluid-guiding means, e.g. diffusers
  • F04D29/541—Specially adapted for elastic fluid pumps
  • F04D29/545—Ducts
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/60—Mounting; Assembling; Disassembling
  • F04D29/601—Mounting; Assembling; Disassembling specially adapted for elastic fluid pumps

Definitions

• the invention relates to a fan arrangement in the manner of a mini fan. Such fans are also referred to as small or very small fans.
• Mini fans have very small dimensions. For example, have • the fans of the ebm-papst series 250 dimensions of 8 x 25 x 25 mm, • those of the ebm-papst series 400F dimensions of 10 x 40 x 40 mm, • those of the ebm-papst series 400 of 20 x 40 x 40 mm, and • that of the ebm-papst 600 series of 25.4 x 60 x 60 mm.
• the power consumption of such fans is 0.4 ... 0.6 W for the 250 series, 0.7 ... 0.9 W for the 400F series, and 0.9 .. for the 400 and 600 series. 1.6 W.
• Their typical weight is in the range of 4 to 35 grams.
• Today electronic devices are provided with more and more functions and built into smaller and smaller housings. This causes an increase in the heat loss in the electronic circuit of such a device.
• a particular problem arises from the fact that in such a circuit individual elements become particularly hot, e.g. Power semiconductors, microprocessors, resistors with which a motor current is measured, etc. These particularly hot elements create so-called hot spots on the circuit board, a term borrowed from geology. For example, Iceland has many hot springs and geysers, so many hot spots.
• Such a fan arrangement can be arranged directly on a printed circuit board where the greatest heat loss is generated.
• the collectorless control or regulation of the electric motor of such a fan arrangement can take place by means of switching elements which are integrated in the electronics on the circuit board to be cooled. These switching elements can also change the speed of such a fan arrangement depending on the temperature, so that the speed increases with increasing temperature.
• such a fan arrangement enables a very low overall height, since its bearing unit and the inner stator of its electric motor can be mounted and soldered directly onto the circuit board in a similar way to an electronic component, and since the air guide ring can be mounted as a separate unit on the circuit board, so that the circuit board actually becomes a component of the fan and its overall height is reduced accordingly. This enables the use of higher fan wheels and thus an increase in air performance.
• the fan wheel When the assembly process is complete, the fan wheel can be installed and secured against being pulled off. This also makes it possible for the fan wheel, which is very sensitive in the case of such mini fans, to be mounted at a point in time at which its damage is largely impossible.
• the emerging cooling air can either be directed to specific components, or the air can exit uniformly in all directions and cool all surrounding components evenly. There are many variations here.
• the shape of its fan blades is of great importance in order to achieve high cooling capacities.
• the number of blades, their angle of attack to the hub and the blade radius are important parameters. If an axial fan wheel is used, good results can be obtained by using approximately trapezoidal fan blades. Also a radius-shaped one Blade curvature in the radial direction can be advantageous.
• a radial fan wheel has special advantages for applications on printed circuit boards.
• the fan blades are preferably embedded in an upper and a lower air guide plate, which results in an optimal air flow.
• the air guide plates have the characteristic of a diagonal fan and have corresponding cross-sectional profiles.
• FIG. 1 is a plan view of a circuit board 17, in which a fan arrangement 16 for local heat dissipation is arranged at a point with particularly high heat development,
• FIG. 2 shows a section through a printed circuit board and through the inner stator of a mini fan, which is to be attached to this printed circuit board, on a greatly enlarged scale
• FIG. 3 is a further enlarged view of a detail III of FIG. 2,
• FIG. 5 shows a second alternative of the section IV-IV
• 6 shows a representation analogous to FIG. 2, in which the printed circuit board and the inner stator are mechanically and electrically connected to one another,
• FIG. 7 shows a representation analogous to FIG. 6, the rotor belonging to the inner stator (and the fan wheel connected to it) being additionally shown before assembly,
• FIG. 8 is a representation analogous to FIG. 7, but after the marriage of the inner stator and rotor,
• FIG. 9 shows a representation analogous to FIG. 8, which shows the circuit board, the fan attached to it, and an air guide ring, the latter before it is mounted on the circuit board, it being shown in section on the left and uncut on the right,
• FIG. 10 is an illustration analogous to FIG. 9, but after mounting the air guide ring on the circuit board,
• FIG. 12 shows the arrangement according to FIG. 10 after its assembly in the housing of an electrical device
• FIG. 13 is a spatial, highly schematic representation of the fan rotor for the motor of FIG. 10,
• FIG. 16 is a schematic illustration for explaining Fig. 17, and FIG. 17 shows a spatial representation of a rotor, as can preferably be used in the fan arrangement according to FIG. 12.
• Fig. 1 shows a plan view of a circuit board 17 on which various electronic components are arranged.
• components 11 which generate a particularly large amount of heat during operation and thus a hot spot.
• a fan arrangement 16 of the type described in more detail below using examples.
• the fan arrangement 16 brings about targeted cooling of the components 11 since it generates a uniform air flow 13 in all directions. It is only shown schematically in FIG. 1. Preferred embodiments result from the following figures.
• the air flow 13 can also be directed specifically at individual components, and that in sectors where little cooling air is required, the air flow can be reduced accordingly.
• this would be e.g. the sector between 4 a.m. and 5 a.m., and between 8 a.m. and 9 a.m., where the density of the components 11 is relatively low and consequently less heat has to be dissipated.
• This control of the air flows is e.g. possible by blinds, or in many other ways. For this, reference is made to specialist literature.
• the mini fan 16 is driven by an external rotor motor 18 (FIG. 8), and FIG. 2 shows the circuit board 17 to which the stator 44 of the motor 18 is attached.
• the motor 18 has an outer rotor 22 with a rotor bell 24, on the outer circumference of which there are provided fan blades 26, which are also referred to as fan blades.
• a magnetic yoke 27 made of soft iron
• a radially magnetized rotor magnet 28 (FIG. 8), which can be magnetized, for example, with four poles.
• the outer diameter D (FIG. 7) of the outer rotor 22 can be, for example, in the range from approximately 14 to approximately 35 mm. Naturally, the use of the invention is not excluded even with larger engines, but this area is the main area of application.
• the rotor bell 24 has in its center a hub 30, in which a correspondingly shaped upper shaft end 32 of a rotor shaft 34 is heat-conductively fastened by plastic tips or the like, the lower, free shaft end of which is designated by 35.
• the diameter of the end 35 decreases towards the bottom.
• a slide bearing 36 which is preferably designed as a double sintered bearing, is used for the radial mounting of the shaft 34.
• bearings with roller bearings are also possible to achieve particularly long lifetimes.
• the plain bearing 36 is fastened in a bearing tube 38 by pressing.
• the bearing tube 38 is preferably made of steel, brass, or another suitable material. The use of a plastic is also not excluded.
• the bearing tube 38 is provided with a radial projection in the form of a flange 39, which in this example runs approximately perpendicular to the axis of rotation 41 of the rotor 22.
• the inner stator 44 of the motor 20 is fastened on the outside of the bearing tube 38, preferably by being pressed on, cf. Fig. 2.
• the sintered bearing 36 has a bulbous section 42 with a diameter which corresponds approximately to the diameter of a cylindrical section of the inside 40 of the bearing tube 38 and is dimensioned such that a tight fit is obtained during assembly.
• the sintered bearing 36 has a lower slide bearing section 48 and an upper slide bearing section 50. This enables a reliable mounting of the shaft 34 and a correspondingly long running time of the motor 20, even at the high speeds of these mini fans, which are often in the range from 6000 to 9000 rpm.
• the stator 44 has a laminated core 45 which is encapsulated with a coil former 46, on which a winding 47 is wound.
• the stator 44 could e.g. also be designed as a claw pad stator.
• the shaft 34 has an annular groove 58, which in FIG. 7 is shown and in which elastic securing hooks 60 are engaged after assembly, cf. Fig. 8. These hooks 60 have a smaller axial extent than the annular groove 58, and their function is to secure the rotor 22 against unintentional removal.
• the elastic locking hooks 60 do not abut against the shaft 34 at any point. They are formed in one piece with a cover 62 and are located on a lubricant reservoir 64, on the bottom of which there is a depression 66, in which a track tip 68 (FIG. 7) of the shaft 34 rotates. The depression 66 and the tip 68 together form an axial bearing for the shaft 34.
• the bearing tube 38 has a hollow cylindrical section 42 in its upper region, and this extends downwards in the manner of a hollow truncated cone 70 which merges below into an approximately cylindrical section 71, in which annular grooves 72, 73 are incorporated with an approximately semicircular cross-section, cf. 3.
• the cylindrical section 71 widens downward in the manner of a truncated cone 74.
• the bearing tube 38 has a cylindrical section 75 on top, onto which the inner stator 44 is pressed, cf. Fig. 2, and the section 75 goes over a shoulder 76 into the top of the flange 39. This forms a stop for the coil former 46 during assembly, cf. Fig. 2.
• the underside 77 of the flange 39 in turn merges into a cylindrical section 78 on the outside of the bearing tube 38.
• This section 78 has a larger diameter than section 75, and it continues in the cylindrical outside 79 of the latching cover 62, so that the bearing tube 38 and the latching cover 62 together form a cylindrical outside, which is designed according to FIGS. to be pressed into a cylindrical opening 80 of the printed circuit board 17.
• the locking cover 62 has on its outside 83 locking beads 84, 85, which are only visible in this enlarged view. If the snap-on cover 62 is pressed into the opening 71 with a press fit, the beads 84, 85 form a slight snap and at the same time represent an excellent seal, so that no lubricant can run out of the depot 64.
• the elastic plastic used for the cover 62 is so heat-resistant that it is not damaged in a solder bath as it passes through it.
• the flange 39 has either the shape according to FIG. 4 with four radial grooves 92, or the square shape 39 ′ according to FIG. 5.
• the printed circuit board 17 has corresponding holes 94, into which these wire pins 88 are inserted during assembly and then soldered with a solder 96 in the solder bath, the solder 96 rising as a result of capillary action through the hole 94 and also soldering the winding connection 90 to the pin 88.
• This solder 96 then simultaneously represents the electrical and mechanical connection of the inner stator 44 to the printed circuit board 17.
• This simple type of attachment is possible because such a mini fan only has a weight of e.g. Has 20 g.
• the hub 30 has an undercut 112 at its lower end in FIG. 7, which throws the lubricant outwards.
• the bearing tube 38 also has an undercut 114 on its inside on its upper end, which prevents the fan 16 from leaking out of lubricant when the fan is inclined. For this reason, the gap 116 between the bearing tube 38 and the rotor 22 is very narrow and is dimensioned in the manner of a capillary gap in order to prevent lubricant from escaping.
• the lubricant flung to the outside by the undercut 112 flows along the inner wall 46 of the bearing tube 38 downward to the sintered bearing 36 and through this further down into the storage container 64 there is always a sufficient supply of lubricant in the reservoir 64 and its recess 66.
• the cylindrical part 71, 79 of the bearing tube 38 is first pressed into the opening 80 of the printed circuit board 17, resulting in the image according to FIGS. 6 and 7.
• the circuit board 17 is soldered in the usual manner in a solder bath. (The components 11 are not shown in FIGS. 2 ff.)
• the rotor 22 is then married to the inner stator 44, the safety members 60 first being deflected outwards according to FIG. 8 and then snapping into the annular groove 58 of the rotor shaft 34 and thus preventing the rotor 22 from being pulled off again can be. To avoid friction losses, the safety members 60 do not rest against the annular groove 58. This increases the efficiency of such a small or very small motor.
• the rotors 22 can be transported separately and only installed on site, with corresponding lubricant having to be filled into the depot 64, 66 beforehand. Transport with mounted rotors 22 is also possible.
• the magnet 28 is not arranged symmetrically with respect to the axial direction of the motor 20 relative to the stator plates 45, but instead is offset upwards relative to these, a magnetic force acts on the rotor 22 in the downward direction, and this presses the tip 68 into the recess 66 and prevents the rotor from rattling in the event of vibrations.
• the fan 16 is checked in the usual way.
• the commutation can e.g. by means of the induced voltage, for which purpose a corresponding sensor winding is provided, or a semiconductor sensor is used which detects the position of the rotor 22.
• an air guide member 110 is provided, which is mounted around the fan 16 according to FIG. 10 in order to improve its efficiency. you also designates this member as air guide nozzle 100, or as an air nozzle, or as an outer housing of the fan.
• annular flange 102 which is provided with an annular groove 104 for a sealing ring 106. It also has a lower flange 108 which, as shown, is inclined upwards by an angle 8 (delta), e.g. by 7 °.
• the annular flanges 104, 108 are connected to one another by a tubular section, the lower part 117 of which is cylindrical and the upper part 118 of which is in the form of a truncated cone which widens towards the top. This shape creates a venturi effect and improves fan performance.
• FIG. 9 shows only two spacers 120 and two latching hooks 122.
• the air guide member 100 is hooked into corresponding recesses 124 of the printed circuit board 17 by means of its latching hooks 122, the spacers 120 with lower, pin-shaped sections 121 of smaller diameter being inserted into corresponding recesses 123 of the printed circuit board 17 and the air guide member 100 at a predetermined distance Hold L (Fig. 10) off the PCB 17.
• This type of attachment is very simple and reliable.
• the air guide ring 100 can first be mounted in the manner described, and only then is the rotor 22 mounted.
• the advantage is that in this case the rotor 22 is included assembly of the air guide ring 100 cannot be damaged. In such small and very small fans, the rotor 22 is due to its extremely thin shaft 34 and its small size, which is pronounced of a toy, particularly sensitive and must be treated carefully and like a raw egg. In this case, in FIG. 11 the rotor 22 is inserted through the opening of the air guide ring 100, this serving as a guide.
• FIG. 12 shows the arrangement according to FIG. 10 after installation in an electronic device 130.
• the flange 102 in this case lies with its sealing ring 106 against the upper housing wall 132 in FIG. 12, which has an air inlet opening 134 in the middle, which is the same size as the upper opening of the air guide ring 100.
• a protective grille 136 is engaged on the wall 132 and is provided with a plurality of openings 138.
• a dust filter 139 can also be located under the protective grille 136, e.g. to prevent sand or animals from entering.
• the path of the intake air is indicated at 140. If necessary, it can also exit the device 130 laterally through corresponding openings.
• FIG. 13 to 15 show a preferred form of the fan blades 26 for an axial fan wheel, as shown in FIG. 13.
• the axial length of the blades and their geometry are of great importance, especially with such small fans.
• FIG. 13 shows the direction of rotation 141.
• the fan blades 26 extend axially over the entire axial length of the rotor 22.
• FIG. 13 shows the "normal" shape of such blades for comparison with dashed lines.
• the rear part 142 of the normal wings 26, as seen in the direction of rotation is not present, so that an approximately trapezoidal wing shape results.
• the reason for this shape of the vanes 26 which differs from the "normal shape” is that this facilitates the lateral outflow of the conveyed air, as shown at 127 in FIG. lateral pressure build-up is improved.
• With the "normal" wing geometry only a slight pressure build-up in the lateral direction and consequently only a small cooling air flow onto the printed circuit board 17 would be obtained.
• x1> x2 i.e. x1 represents the base of a trapezoid.
• Fig. 14 shows such a wing in development. The front edge is labeled 144 and the rear edge is labeled 146. The direction of rotation 141 is also entered.
• FIG. 15 shows a section, seen along the line XV-XV of FIG. 14. It can be seen that the wings 26, also seen in a radial section, are curved and have a radius of curvature R. R preferably has a value that is ⁇ xi.
• the curvature R brings about a slight reduction in the pressure build-up, but the radial outflow of air (arrows 127 in FIG. 13) is thereby improved.
• This curvature (radius R) advantageously favors the pressure build-up in the area of the air guide ring 00.
• FIG. 16 schematically shows a radial fan wheel 160 that rotates clockwise as indicated by arrow 141.
• a radial fan blade 162 extends from the outer rotor 22 and is curved forward, and its radially outer section forms an angle cti (alphal) with the periphery 164 of the fan wheel 160 which is greater than 90 °.
• a radial fan blade 166 is shown in FIG. 16 depicted, which is bent backwards ie, it includes radially outer portion to the periphery 164 at an angle 0. 2 (alpha2) a which is smaller than 90 °.
• Blades 162 which are curved forward achieve a greater deflection of the flow, that is to say a greater conversion of energy into moving air.
• a spiral housing is required for them and pressure must first be built up by means of a diffuser which is connected downstream from such an impeller with blades 162.
• FIG. 17 shows a preferred embodiment of such a radial fan wheel 170 with backward curved blades 166, in which the convex side rotates forward, which is why a spiral housing and a diffuser can be omitted here.
• an air guide ring 100 is advantageously used, as shown in FIG. 9, but only the part 108 is required and the sections 102 and 118 can be omitted.
• the fan wheel 170 has an upper air guide plate 172 with a curved cross section, the preferred cross sectional shape of which corresponds approximately to the sector of an ellipse. Furthermore, the fan wheel 170 has a lower air guide plate 174 which, viewed in cross section, runs approximately parallel to the upper plate 172. Both plates extend to the air inlet opening 134, the upper edge of the plate 172 being arranged very close to the edge of the opening 134.
• the fan blades 166 are embedded in the area of the outlet between the plates 172, 174 in the manner shown and are curved backwards, cf. Fig. 17, i.e. the pressure build-up already takes place in the fan wheel.
• a stationary air guide plate 108 is preferably arranged around the fan wheel 170, which is aligned with the outer edge of the upper air guide plate 172 and, together with the printed circuit board 17, forms an air passage channel which widens somewhat towards the outside. In this way, a targeted air flow can be generated, so that components 11 which are further away can also be cooled. If all of the components 11 to be cooled are in the vicinity of the fan, the stationary air guiding plate 108 may be dispensed with. This is fastened in exactly the same way as the air guide member 100 of the first exemplary embodiment, that is to say with the same latching hooks and spacers, which is why they are not described again. Here, too, the installation of the air guide plate 108 is extremely simple.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Motor Or Generator Cooling System (AREA)
• Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=34625923

Family Applications (1)

Country Status (5)

Families Citing this family (7)

Family Cites Families (42)

• 2005
  • 2005-02-12 AT AT05701406T patent/ATE485451T1/de active
  • 2005-02-12 WO PCT/EP2005/001437 patent/WO2005106254A1/fr not_active Application Discontinuation
  • 2005-02-12 US US10/544,811 patent/US8801375B2/en not_active Expired - Fee Related
  • 2005-02-12 DE DE502005010421T patent/DE502005010421D1/de active Active
  • 2005-02-12 EP EP05701406A patent/EP1747378B1/fr not_active Not-in-force
  • 2005-03-15 DE DE200520004092 patent/DE202005004092U1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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