Mini-fan
A mini-fan has a fan wheel (64) equipped with fan blades (80), and an electrical drive motor (61) for driving that fan wheel. The drive motor (61) has a permanent-magnet external rotor (62) and an internal stator (90), which latter is implemented as a claw pole stator having pole pieces (88, 110) whose claw poles (84, 86) engage into one another. Arranged between the pole pieces is a coil former (57) that comprises a central portion (54) to which are joined two side parts (50, 56), located opposite one another, one of which is implemented as a carrier for electrical elements (96, 98) of the motor (61).
This application is a section 371 of PCT/EP2005/013261, filed 10 Dec. 2005, which claims priority from German application DE 20 2005 003412.6, filed 24 Feb. 205, the entire content of which is incorporated by reference.
FIELD OF THE INVENTIONThe invention relates to a mini-fan. Such fans are also referred to as miniature or subminiature fans.
BACKGROUNDSensor fans are used for air measurement, e.g. for air-conditioning systems in motor vehicles. These fans have, for example, an outside diameter of 30 mm, i.e. these are what is referred to in technical jargon as mini-fans.
Mini-fans of this kind also serve to cool processors in computers, for equipment cooling in small equipment, etc., and their dimensions are very small. For example:
- fans of the ebm-papst 250 series have dimensions of 8×25×25 mm;
- those of the ebm-papst 400F series have dimensions of 10×40×40 mm;
- those of the ebm-papst 400 series have dimensions of 20×40×40 mm; and
- fans of the ebm-papst 600 series have dimensions of 25×60×60 mm.
The power consumption of such fans is 0.4-0.6 W for the 250 series, 0.7 to 0.9 W for the 400F series, and 0.9-3.4 W for the 400 and 600 series. Their weight is, for example, approximately 5 g for the 250 series, between 17 g and 27 g for the 400/400F series, and approximately 85 g for the 600 series.
In fans of this miniature size, which must be very inexpensive, it is important to make the assembly thereof extremely simple, so that they can be manufactured with a high degree of automation and so that such fans exhibit uniform quality and low noise.
A further complicating factor with such extremely small fans is that their components, entirely analogously to those of a mechanical clock mechanism, are very delicate and therefore not very robust. The rotor shaft, for example, is often only as thick as a knitting needle and therefore can easily be bent if handled carelessly, rendering the fan unusable. The same applies to pole pieces.
SUMMARY OF THE INVENTIONIt is therefore an object of the invention to make available a novel mini-fan.
According to the invention, this object is achieved by configuring a coil former, arranged between two pole pieces of the stator, to also serve as a carrier for electrical elements of the motor, such as terminals of a sensor winding. Because a portion of the coil former is implemented as a carrier on which electrical elements of the motor can be arranged, e.g. components, connector elements, or the like, a very simple and compact design is obtained; this is extremely important, specifically for mini-fans. Another advantage that results is that of a low-vibration configuration, so that such a mini-fan consequently operates in low-noise fashion.
BRIEF FIGURE DESCRIPTIONFurther details and advantageous refinements of the invention are evident from the exemplifying embodiment, in no way to be understood as a limitation of the invention, that is described below and depicted in the drawings.
Proceeding from air inlet opening 14, housing 12 widens via an annular portion 18 into a cylindrical portion 20.
A circuit board 22 rests on annular portion 18, and a sealing ring 24 made of sponge rubber is mounted on that board in the manner depicted.
Circuit board 22 is substantially round and has at its center a crosspiece 26, of which only the rear half is visible in
NTC resistor 28 (using SMD or Surface Mounted Device design) is connected via conductors 34 to contact pins 36, 38 that are arranged in insulated fashion, as depicted, in cylindrical part 20 of external housing 12. These metal pins 36, 38 each have at the bottom a contacting foot 36′, 38′, respectively, each of which has two resilient elements 40, 42 that are depicted in
Cylindrical part 20 of external housing 12 is closed off at the bottom by a carrier 50 at whose center is arranged a metal bushing 52. The latter is surrounded by a cylindrical portion 54 that is integral with circuit plate 50 and transitions at its upper end into an annular disk 56 that, together with parts 50 and 54, constitutes a coil former for a stator winding 58. Circuit plate 50 has on its outer rim notches 51 through which contact pins 36 and 38, as well as other contact pins 53, project.
Located inside bushing 52 is a sintered bearing (not depicted) for shaft 60 of external rotor 62 of a motor 61. Rotor 62 has a supporting part 64 made of plastic that has at its center a hub 66 into which the upper end of shaft 60 is injection-embedded, said end having a knurled portion 68 for better anchoring. External rotor 62 has approximately the shape of an upside-down bowl, and has at its periphery a rim portion 70 that extends approximately parallel to shaft 60.
As depicted, a permanent magnet 72 is directly injection-embedded into this rim portion 70 using the two-component injection method. Magnet 72 is made of hard ferrites in a plastic matrix, and this plastic with its hard-ferrite particles 74 (which of course can be depicted only schematically) can therefore be injection-embedded, for example as a ring, into carrier part 64, in which context the interfaces, which are symbolized by dot-dash lines, are intimately joined by contact melting of the plastics.
Subsequent to the injection-embedding of magnet ring 72, the latter is radially magnetized in a suitable apparatus, as symbolically depicted in
Radially extending fan blades 80 are implemented integrally with carrier part 64, i.e. the fan is preferably a radial one.
A great advantage of the invention is that with this manufacturing method, external rotor 62 is already largely balanced once the plastics have been injected, so that only minor balancing work, at most, is necessary. An economy is also achieved in terms of assembly, since it is just such extremely small parts that are difficult to handle and assemble, and errors might therefore easily occur during assembly. The invention eliminates waste, since rotor 62 with its rotor magnet is available during assembly as a completed and tested part that simply needs to be installed in the bearing, this usually being done by inserting shaft 60 into the bearing.
In the fan according to
Portion 83 is formed by the fact that during manufacture, material of carrier 50 travels through openings 85 of bushing 52 into the latter's interior (cf.
As FIGS. 5 to 10 show particularly clearly, fan 10 has an internal stator 90 that is implemented as a claw-pole design.
Coil former 57, already described, has wound onto it a coil 58 that usually has two separate windings that are wound in bifilar fashion, for example a drive winding having two terminals 92, 94, and a sensor winding having two terminals 96, 98 (cf.
As depicted, terminals 92 to 98 are guided to lateral contacts that are embedded into circuit plate 50 (preferably using the MID method) and that are each connected to associated contact pins 53 that extend through grooves 51 and thereby create an electrical connection to metal coatings 100 provided there.
Two barbs 102, 104 are shaped onto the bottom of carrier 50 (cf.
- a) covers the outer side of claw poles 84, 86 (cf.
FIG. 9 ); and - b) extends, approximately in the shape of annulus segments 114, 116, into gaps between the adjacent claw poles 84, 86 (cf.
FIG. 6 ).
Each of these annulus segments 114, 116 is equipped with a respective projection 118, 120 (
Lower pole piece 110 is, in the same fashion, pressed with its central opening onto bushing 52 and then welded to carrier 50.
As
In
In
In
In
in
The term “molded interconnected device” (MID) is also applied to this manufacturing method.
By means of this manufacturing method, the connections necessary for the electronics are applied directly onto coil former 57. The injection-molded parts manufactured in this fashion are immediately ready for further processing. Holes or adaptations no longer need to be incorporated after the fact, but instead are integrated directly into the components by way of the injection-molding manufacturing molds. In addition to the quality advantages and the reduced manufacturing complexity, this method also offers positive environmental features by omitting lead-containing solder and eliminating circuit boards made of materials that usually cannot be recycled, and reliability is enhanced at low cost.
Be it noted that in
Provided around air inlet opening 14′ in
Contact pins 148, 150 extend through housing 146 and project downward out of it.
Prior to the manufacture of housing part 212, these magnets are placed into an injection mold and retained there at the points labeled 228 in
The magnets are then injection-embedded in the plastic of the lower housing part so that they are fixedly anchored in that housing part and cannot fall out.
These magnets 226, 228 serve to rotate rotor 62, prior to starting, into a position from which it can easily start.
The invention thus yields a mini-fan having a very compact and robust internal stator 90. The reader must bear in mind in this context that when the outside diameter of mini-fan 10 in
a) at low cost; and
b) with great precision.
It must further be kept in mind that many claw poles can have, for magnetic reasons, shapes that are substantially more complicated than the shape depicted in
Many variants and modifications are of course possible within the scope of the present invention.
Claims
1. A mini-fan having
- a housing defining an air inlet opening (14):
- a fan wheel (64) equipped with fan blades (80) for pulling air in through said air inlet opening (14);
- an electrical drive motor (61) for driving that fan wheel, said drive motor (61) including
- a permanent-magnet external rotor (62);
- an internal stator (90), having sheet-metal pole pieces (88, 110) formed with claw poles which interdigit with each other, and
- a coil former (57) located between said pole pieces (88, 100) and having a central portion (54) connecting two mutually opposed side pieces (50, 56), wherein at least one of said side pieces (50) serves as a carrier for electrical components (96, 98) of said drive motor (61).
2. The mini-fan according to claim 1, wherein
- the carrier (50) is formed with orifices (122, 124) for insertion of the claw poles of the pole piece (110) adjacent to it.
3. The mini-fan according to claim 2, wherein
- at least the pole piece (110) adjacent to the carrier (50) is equipped, at least locally, with a plastic part (114, 116) that is fixedly bound to the carrier (50).
4. The mini-fan according to claim 3,
- wherein the plastic part (114, 116) extends into a region between two adjacent claw poles (84, 86).
5. The mini-fan according to claim 3, wherein
- the plastic part (114, 116) is equipped, on its side adjacent to the carrier (50), with a projection (120), which projection is welded to the carrier (50).
6. The mini-fan according to claim 3, wherein
- the plastic part (114, 116) extends at least partially over at least one of said claw poles (84, 86).
7. The mini-fan according to claim 6,
- wherein a claw pole (84, 86) is equipped with recesses (126) into which plastic of the plastic part (114, 116) engages.
8. The mini-fan according to claim 1, further comprising
- a tube (52) made of soft ferromagnetic material, arranged inside the coil former (57).
9. The mini-fan according to claim 8,
- wherein the tube (52) of ferromagnetic material functions as a magnetic return path for the pole piece (88, 110).
10. The mini-fan according to claim 8,
- wherein the tube (52) is equipped, near the carrier, with at least one recess that extends over a portion of the tube periphery and through which plastic of the coil former (57) extends into the interior of the tube (52).
11. The mini-fan according to claim 10,
- wherein the plastic that extends into the interior of the tube (52) is configured to serve as part of an axial bearing for journaling the permanent-magnet external rotor (62).
12. The mini-fan according to claim 1, wherein said fan housing (12) defines a generally circular air inlet opening (14) and
- a sealing ring (24) of elastomeric material is provided adjacent a rim of said air inlet opening (14).
13. The mini-fan according to claim 12,
- wherein the sealing ring (24) is arranged on a circuit board (22) that is provided adjacent the air inlet opening (14).
14. The mini-fan according to claim 13, further comprising
- a temperature sensor (28), arranged on the circuit board (22).
15. The mini-fan according to claim 14,
- wherein the circuit board (22) comprises a strut (26) that extends into an airflow path defined by said air inlet opening (14) and serves as a carrier for the temperature sensor (28).
16. The mini-fan according to claim 1,
- wherein a temperature sensor (28) is provided; and conductors (140, 142) leading to the temperature sensor (28) are applied onto housing portion (144) of said fan using a hot-stamping method.
17. The mini-fan according to claim 1,
- wherein the fan blades (80) extend substantially parallel to the rotation axis (82) of the mini-fan.
18. The mini-fan according to claim 1,
- wherein said housing (20; 220) has at least one lateral air outlet opening (16).
19. The mini-fan according to claim 1,
- further comprising
- mounting feet (53; 36′, 38′) that also serve, at least in part, for electrical connection of the fan.
20. The mini-fan according to claim 1, wherein
- a two-phase stator winding (58) that is wound in bifilar fashion is provided on the coil former (57).
21. The mini-fan according to claim 1, wherein
- a housing part (212), in which at least one permanent magnet (226, 228) is mounted by plastic injection molding, is provided adjacent the rotor (62).
22. The mini-fan according to claim 21,
- wherein the at least one permanent magnet is implemented as a plastic-matrix flexible magnet (226, 228).
Type: Application
Filed: Dec 10, 2005
Publication Date: Jun 14, 2007
Inventor: Rodica Peia (Zimmern ob Rottweil)
Application Number: 10/597,045
International Classification: F04B 17/00 (20060101);