Patent Application
20170335861
The invention concerns a fan wheel according to the preamble of claim 1.
Generally, fan wheels can be understood as radial fan wheels, diagonal fan wheels, axial fan wheels but also inlet or outlet guide wheels (stators) of fans.
Fan wheels are manufactured of different materials. For example, they can be produced from fiber reinforced plastic materials as one piece. Up to a certain outer diameter, such a fan wheel manufacture has been proven successful. For greater sizes, the required investment in injection molding tools as well as the price of parts due to the high machine units for large injection molding machines increases however so much that a realization is no longer cost-effective. Also, the cylinders of the injection molding machines in general are not capable of heating more than 15 kg of melted fiber reinforced plastic material to sufficiently high temperatures.
For this reason, it is also known to produce such fan wheels of several parts. For example, it is known (DE 41 39 293 A) to join end to end box-shaped or U-shaped segments with material fusion or form fit and to attach to the top side and the bottom side of these joined elements a hub ring as well as a cover ring by gluing or welding. As a result of the great number of individual parts, the manufacture of such impeller wheels is complex, time-consuming, and accordingly expensive because initially the segments must be joined end to end and in further steps the cover ring as well as the hub ring must be attached.
Fan wheels are also known in which the vanes are detachably connected to a hub with which the fan wheel is seated on a drive shaft (DE 10 2009 008 508 A1).
Furthermore, fan wheels are known (WO 20012/131 617 A1) in which the vanes are embodied in the form of hollow segments. They are joined end to end and subsequently held together by means of a disk and a cap which are fastened to the top side and to the bottom side of the assembled vane segments. Such fan wheels can be manufactured and assembled only with great expenditure. Initially, the vane segments must be joined and positioned. Only subsequently, the disk as well as the cap are placed onto the two sides of the assembled vane segments and connected to them.
Moreover, fan wheels are known (US 2003/0235502A) which are assembled of block-shaped segments. The block-shaped inner and outer parts that form cylindrical outer and inner rings are contacting each other with their axially extending faces. Such fan wheels have a high weight and are suitable only for special application situations.
The invention has the object to design the fan wheel of the aforementioned kind such that it can be produced inexpensively and in a simple way. In this context, the fan wheel should have only minimal weight and be able to withstand high loads, in particular high rotary speeds.
This object is solved for the fan wheel of the aforementioned kind in accordance with the invention by the characterizing features of claim 1.
In the fan wheel according to the invention, the joining areas are enlarged in their surface area by the projecting form fit part and the correlated recess so that the fan wheel assembled from the segments has a high stability and strength. A joining surface enlarging design differs from a conventional design in that the cross section through the joining areas does not have the shape of a straight connecting stretch that connects the two walls of the ring along a short path and extends approximately perpendicular to the walls. When the segments are connected to each other by means of an adhesive, due to the joining surface enlarging design the gluing surface is enlarged which leads to an increase of the strength of the fan wheel. This applies likewise when neighboring segments are areally welded at the joining areas to each other. In addition, due to this joining surface enlarging design, an additional form fit connection between neighboring segments is formed so that displacements of the segments relative to each other transverse to the circumferential direction are prevented. Also, with such a design, joining of the segments in the manufacturing process can be facilitated because the guide elements form an additional guiding means of neighboring segments relative to each other. The form fit parts and the recesses form a tongue and groove connection that leads to a secure connection of the segments. Neighboring segments are joined during the manufacturing process axially or radially or in a mixed form of axial and radial so that the projecting form fit part reaches the recess of the respectively adjoining ring section cut of the neighboring segment. With the embodiment according to the invention, the joining surface is significantly increased without the wall thickness of the ring sections being enlarged. As a result of the embodiment according to the invention, the manufacturing process of the fan wheel according to the invention can be designed to be very economical, quick, and precise.
In the fan wheel according to the invention, segments that are embodied as one piece are used which comprise ring sections as well as vanes or vane sections. The ring sections extend substantially transverse to the vanes or vane sections and extend with a directional component in circumferential direction of the fan wheel. The rims of the ring sections which are positioned transversely to the circumferential direction of the fan wheel form the joining areas in the joined fan wheel. The segments that are contacting each other are connected at the joining areas in such a way with each other that, despite the minimal wall thickness of the ring sections, a sufficiently strong connection between the segments is possible. In the joined state, the ring sections of the segments as a whole form one or several rings. Rings can be in particular hub rings or cover rings which connect the vanes at their lateral ends with each other in circumferential direction, or intermediate rings which are connected with the vanes in their intermediate areas between their lateral ends. The hub ring serves advantageously for connecting the fan wheel with a drive motor. In case of stators, the cover ring serves advantageously for fastening the stator on another device.
Advantageously, the form fit part tapers in the direction toward its free end. In this way, joining of neighboring segments is significantly simplified.
In an advantageous embodiment, the recess is arranged in the area between the top side and the bottom side of the ring section. Advantageously, the recess and accordingly also the form fit part can be provided approximately at half the thickness of the ring section.
In another advantageous embodiment, the recess is open toward the top side or toward the bottom side of the ring section. Such an embodiment enables a simple and problem-free joining process when producing the fan wheel. Since the recess is open toward one side of the rim section, neighboring segments can be very easily joined end to end in axial direction of the fan wheel during manufacture.
In such a case, the rim of the ring sections comprising the form fit part as well as the recess is advantageously of a stepped embodiment. Such elements can be very easily manufactured with regard to manufacturing technology.
It is advantageous when the recess has a depth that amounts to approximately 0.7 to 2.5 times the wall thickness of the ring section.
In a preferred embodiment, the form fit part is resting with at least one of its side faces on the side wall of the recess. It is advantageous when the form fit part is resting with both side faces on the side walls of the recess. In this case, neighboring segments are securely and fixedly connected to each other.
In principle, it is however also possible that between the side faces and/or the end face of the form fit part and the side walls and/or the bottom of the recess a free space remains.
The spacing of the form fit part relative to the side walls and/or to the bottom of the recess produces the free space into which, for example, a viscous adhesive can be introduced. This adhesive can be introduced into recess prior to joining of the segments.
Advantageously, the transition of at least one side face of the form fit part into the rim of the ring section is curved, preferably at a radius which is approximately 0.05 to 0.3 times the wall thickness of the ring section. The transition is realized advantageously bionically, i.e., without constant radius. The bionic design has the advantage that the transition in regard to the force flow from the form fit part into the ring section of the respective segment can be designed such that a crack formation is reliably prevented. In this way, the transition can be matched optimally to the loads that are occurring in use of the fan wheel.
In an advantageous embodiment, the areas of the ring section between the side walls of the recess and the top side as well as bottom side of the ring section are approximately of the same thickness.
The ring section can however also be designed such that these areas between the side walls of the recess as well as the top side and the bottom side of the ring section have different thicknesses. In this case, the area which in use of the fan wheel does not contribute or contributes only little to the force transmission can be designed thinner than the oppositely positioned area.
In order to achieve a secure connection of neighboring segments without impairment of the strength of the fan wheel assembled from the segments, it is advantageous when one side face of the form fit part is greater than the oppositely positioned other side face.
In order to further enlarge the area which is transmitting the force upon joining of the segments to the fan wheel, the wall thickness of the ring section is advantageously greater in the recess than the wall thickness in the area outside of the recess.
The segments are at least approximately identically embodied. Preferably, all segments have the same shape so that for their manufacture only a single injection molding tool is required; this keeps the manufacturing costs low.
The cover ring sections, hub ring sections, and intermediate ring sections of neighboring segments are preferably embodied such that their rims positioned transversely to the circumferential direction are substantially congruently resting against each other and form paired joining areas, respectively, with which neighboring segments are contacting each other areally. In this way, a simple and still secure connection of the segments resting against each other is ensured.
These joining areas can be positioned in a plane which is defined by the fan wheel axis and a radial line. Depending on the situation of use and the requirement profile, the joining areas of neighboring segments can also be designed such that they are positioned at an angle relative to the respective plane defined by the fan wheel axis and the radial line. The angle can be between 0° and approximately 80° in this context.
Neighboring segments can be connected to each other at the joining areas by means of gluing and/or welding.
A particularly advantageous embodiment of the fan wheel resides in that the inflow side and outflow side ends of the vanes have a spacing relative to the joining areas of the fan wheel. In this case, exclusively the rims of the ring sections which are extending transversely to the circumferential direction of the fan wheel are serving as connecting surfaces.
However, it is also possible that additional joining areas between neighboring segments are extending through the vanes. In this case, the complete vanes are formed not until joining of the segments occurs. In this case, the butt joints of the vane sections also form joining areas which are provided in addition to the rims of the ring sections. In this way, the fixed connection between the segments can be improved.
The segments are advantageously injection molded parts that can be produced in a simple and inexpensive way.
Advantageously, thermoplastic materials are employed as material for the segments.
For increasing the strength of the segments and thus of the fan wheel, the thermoplastic materials contain reinforcement parts, preferably reinforcement fibers.
The reinforcement fibers have advantageously lengths of approximately 10μ to more than 15 mm, preferably lengths of approximately 200μ up to approximately 10 mm. Such reinforcement fibers can be easily worked into the plastic material and ensure a high strength.
As adhesives for connecting the segments with each other, for example, 1-component or 2-component adhesives or solvent systems are conceivable.
A further advantageous connecting possibility resides in connecting the segments by means of laser welding, induction welding or hot gas welding to each other.
In particular in case of great diameters of the fan wheel, an advantageous embodiment resides in that at least one reinforcement strap is wound about at least one ring of the fan wheel. It holds the segments additionally fixedly together so that the fan wheel can be used even at higher rotary speeds or other high loads.
The reinforcement strap can be made of thermoplastic material or thermosetting resin and advantageously can contain reinforcement parts, preferably reinforcement fibers.
As reinforcement fibers, advantageously glass, carbon, aramid, thermoplastic material or natural fibers are conceivable.
The reinforcement strap can be fastened simply on the circumference of one or more rings of the fan wheel, in particular by welding or gluing.
A further advantageous embodiment resides in attaching the reinforcement strap on the circumference of one or more rings of the fan wheel by winding on a curing thermosetting resin.
A particularly optimal embodiment results when the reinforcement strap is wound with pretension onto the fan wheel. The thus obtained fan wheel is characterized by a high strength. Such a fan wheel can be employed at high rotary limit speeds.
In an advantageous embodiment, the pretension of the reinforcement strap is in the range between approximately 10 N and approximately 10 kN, preferably between approximately 10 to 100 N per mm2 cross sectional surface area of the strap.
A reliable fastening of the reinforcement strap on the fan wheel is ensured when the fan wheel for receiving the reinforcement strap is provided on the rings that are to be provided with reinforcement strap with a circumferentially extending groove. In it, the reinforcement strap can be arranged such that it cannot slip off the fan wheel.
The use of a reinforcement strap can also be advantageously employed when the fan wheel is embodied as one piece, i.e., is not made of segments.
The fan wheel according to the invention can be a radial, an axial or a diagonal fan wheel as well as an inlet guide wheel or outlet guide wheel (stator).
The subject matter of the invention not only results from the subject matter of the individual claims but also from the specifications and features disclosed in the drawings and the description. They are claimed as being important to the invention even if they are not subject matter of the claims inasmuch as they are novel individually or in combination relative to the prior art.
Further features of the invention result from the further claims, the description, and the drawings.
The invention will be explained in more detail with the aid of some embodiments illustrated in the drawings. It is shown in:
In the following, fan wheels are disclosed that are made of plastic material and have in particular a large size and are suitable for high rotary speeds. Herein, fan wheels are understood to include stationary as well as rotating elements of fans with guiding function for a flowing medium which are substantially comprised of two to 40 vanes which are connected to each other by one, two or more rings in circumferential direction. Fan wheels can be, for example, radial fan wheels, diagonal fan wheels, axial fan wheels, but also inlet or outlet guide wheels (stators). The fan wheels are joined of segments that are substantially identical or at least similar relative to each other. In this way, expensive injection molding tools are not required. The manufacture of the fan wheel is cost-efficient. Despite the assembly of the fan wheels from individual segments, they have shape stability even at high rotary speeds. The segments, as will be explained with the aid of the following embodiments, are connected so strongly with each other that the assembled fan wheel withstands high loads, for example, rotary speed loads.
The number of segments of which a fan wheel according to the invention is comprised corresponds preferably to the number of fan wheel vanes. In particular in case of fan wheels with a high number of vanes, one segment may contain also two or more vanes so that the number of segments is reduced. For all segments of the fan wheel only one injection molding tool is required, in particular when the segments are of identical configuration relative to each other. When the segments are similar to each other, generally a single injection molding tool is also sufficient then. The different configuration features of the similar segments relative to each other can then be achieved either by exchangeable mold inserts in the injection molding tool or by postprocessing of some injection molded segments or of the joined fan wheel. The design of the segments and in particular of the vanes can be realized very flexibly because an injection molding tool for a segment, in comparison to an injection molding tool for a complete wheel, can be designed with significantly fewer limitations. For example, a complex split mechanism must often be used in an injection molding tool for producing a fan wheel as a complete molded part in order to be able to demould the vane channels; this is not required in an injection molding tool for producing a segment in advantageous embodiments. Accordingly, even hollow vanes for weight reduction can be designed in a simple way.
The individual segments are connected to each other by means of suitable joining methods for forming the respective fan wheel. As joining methods, inter alia adhesive methods, laser welding methods, friction welding methods, induction welding methods, hot gas welding methods or ultrasonic welding methods are preferably considered. The joining areas between the contacting segments can be selected relatively freely, taking into consideration the operating stresses to be expected when the fan wheel is in use. The connection between the segments can be produced by the disclosed joining methods alone. However, it is advantageous when in addition a form fit connection between the neighboring segments is existing that can serve for providing additional strength as well as for providing a guide during the manufacturing process.
The fan wheel according to
The segment has a cover ring section 1 that has a curved outer rim 2 as well as a curved rim 3 extending parallel thereto. Both ends of the rims 2, 3 are connected to each other by rims 4, 5. Viewed in axial plan view, the rim 4 is approximately adjoining at a right angle the outer rim 2. The oppositely positioned rim 5, viewed in axial plan view, adjoins at an acute angle relative to the outer rim 2. The rim 5 also adjoins at an obtuse angle and the rim 4 at an acute angle the inner rim 3 of the cover ring section 1. The cover ring section, as shown in
Between the cover ring section 1 and the hub ring section 6, a vane 11 is extending which has a curved configuration across its length in the embodiment and has the profile of an airfoil in cross section. The vane 11 is connected with its end 91 associated with the cover ring to the cover ring section 1 and with its end 96 associated with the hub ring to the hub ring 6. The outflow side end 12 of the vane 11 extends approximately at an acute angle while the inflow side end 13, viewed in plan view, is rounded in an arc shape (
The vane 11 extends with its outflow side end 12 close to the rim 5 of the cover ring section 1. With its inflow side end 13 the vane 11, viewed in axial plan view, is projecting past the cover ring section 1 and ends at a minimal spacing relative to the rim 9 of the area of the hub ring section 6 which is projecting past the cover ring section 1.
In deviation from the illustrated embodiment, the vane 11 can also have a different cross section configuration and/or a different extension. The vane 11 cannot only be curved across its length but in addition can also be of a twisted configuration across its length.
The hub ring section 6 comprises near its inner rim 8 at least one through opening 14. It is positioned advantageously approximately at half the width of the projecting hub ring section 6 and serves for passing fastening screws there through with which the fan wheel in a mounting position can be attached to a hub of a drive motor.
The hub ring section 6 can be of a planar configuration. However, it is also possible, as can be seen for example in
In the state joined to a fan wheel (
The fan wheel which is illustrated in perspective view in
The segment I that is illustrated in
Viewed in radial direction, there is also an intermediate ring 71* between cover ring 1* and hub ring 6* in the embodiment according to
The segment I that is illustrated in
In the joined fan wheel, the rims 74, 75 of the intermediate ring section 71 of the respective segments form joining areas 85 (
Between the cover ring section 1 and the hub ring section 6, a vane 11 is extending which, in the embodiment of
The vane 11 of the embodiment with segments according to
In deviation from the illustrated embodiment, the vane 11 can also have another cross section configuration and/or a different extension.
In the fan wheel segment I according to
The hub ring section 6, the cover ring section 1, as well as the intermediate ring section 71 can be cylindrically embodied, in particular in case of an axial fan wheel. However, it is likewise possible, similar to what is illustrated in the embodiment according to
In
The segments illustrated in
The embodiment of an axial fan wheel, which is illustrated in perspective view in
The embodiment according to
In particular in case of a great number of vanes 11, it is also conceivable to provide in one segment more than one vane, for example, 2-4, which leads to a reduced number of segments. However, the injection molding tool for producing a segment then becomes more complex. Also, the number of vanes 11, in case of wanting exclusively identical segments, must be divisible by the number of vanes per segments.
Possibly, depending on the loads to be expected in operation, it may be advantageous to provide the fan wheels according to the invention with further intermediate rings 71* in circumferential direction, in addition to the cover and hub rings 1*, 6*. One or several such additional rings can be located in the area between cover ring 1* and hub ring 6*. Their configuration with rims in the segments and joining areas in the assembled wheel is equivalent to the configuration of cover and hub rings 1*, 6* according to the described embodiments. Intermediate rings 71* can provide additional stability but can also affect the flow positively (efficiency, acoustics). Such additional intermediate rings 71* can also be realized with comparatively minimal expenditure due to the manufacturing principle of segments.
For producing an advantageous embodiment of a fan wheel according to the invention, the segments Ito VII are first arranged in a star shape (
As reinforcement fibers for these materials, for example, glass, carbon, aramid, thermoplastic material (PET, PA) or natural fibers are conceivable, for example, flax, hemp, sisal, jute, or coconut fiber.
In embodiments in which neighboring segments are connected by means of laser welding, a high transparency of the employed plastic material for the employed laser light is required. In order to achieve this, as a polymer a plastic material that is highly transparent for the wavelength of the laser light is employed. This can be achieved by special color pigments in the plastic material. Furthermore, advantageously special reinforcement fibers (in particular, glass fibers) are used which have no or only minimal light refraction at the transition polymer to reinforcement fiber. This is possible by use of a special bonding agent coating on the surface of the glass fibers.
Excellent strengths for the segments and thus for the fan wheel result when the reinforcement fibers in the injection molded segment I to VII have lengths of approximately 50 μm to more than 15 mm. A preferred range is between approximately 200 μm and 10 mm.
When the segments Ito VII are glued together at the joining areas 15, 16, 85, 1-component or 2-component adhesives can be employed for this purpose, such as polyurethane, acrylic, methacrylates or silicones. For gluing, also solvent systems can be employed.
When the segments Ito VII are laser welded to each other at the joining areas 15, 16, 85, advantageously diode lasers, CO2 lasers or NdYAG lasers can be employed for this purpose.
The connection of the segments I to VII at the joining areas 15, 16, 85 can also be produced by friction welding, vibration welding or ultrasonic welding.
The connection of the segments Ito VII at the joining areas 15, 16, 85 can also be carried out by means of induction welding or hot gas welding. As hot gas, air, nitrogen or CO2 is conceivable, for example.
In both cases, the plastic material is softened in the area of the joining areas 15, 16, 85. Under the pressure at which the segments I to VII are pressed against each other at the joining areas 15, 16, 85, a material fusion connection of neighboring segments is thus realized thereby and, after cooling of the joining areas, leads to a secure connection of the segments.
Since the vane 11 and the ring sections 1, 6, 71 are embodied together as one piece and form the segment, a simple, fast, inexpensive manufacture of the fan wheel is possible.
The fan wheel according to
On the rim 5 of the cover ring section 1 as well as on the area of the rim 10 of the hub ring section 6 positioned underneath in a view in axial direction, a cutout 17 with a contour that is approximately mushroom-shaped is provided, respectively. The oppositely positioned rim 4 of the cover ring section 1 as well as the area of the rim 9 of the hub ring section 6 positioned underneath in a view in axial direction are provided with a projecting mushroom-shaped projection 18 engaging the cutout 17 of the neighboring segment. The cutouts 17 and the projections 18 are designed complementary to each other so that they are resting with their rims against each other. Due to the mushroom shape configuration, the cutouts 17 as well as the projections 18, viewed in circumferential direction, are provided with an undercut, respectively.
In deviation from the mushroom shape configuration, the form fit connections can also have other contour shapes. They must only be designed such that the neighboring segments Ito VII in circumferential direction of the fan wheel cannot be separated from each other.
The cutouts 17 and the projections 18 are provided respectively on the cover ring sections 1 and the hub ring sections 6. They can also be provided only on the cover ring sections or only on the hub ring sections, depending on where high loads are to be expected on the respective fan wheel. Several cutouts 17 and complementary projections 18 can be provided also across the length of one rim 4, 9 or 5, 10. The vanes 11 are arranged on the segments I to VII such that they have a spacing relative to the cutouts 17 and the projections 18.
In the meaning of the invention, a projection 18 is a projecting form fit part and a cutout 17 a recess of at least approximately complementary shape on a rim 4, 9, 74 or 5, 10, 75.
In this embodiment, the segments I to VII embodied as one piece are also identical relative to each other so that only one single injection molding tool for the segments is required. The form fit elements 17, 18 provide an additional guide for joining the segments I to VII and ensure also an additional shape stability when the fan wheel is loaded in circumferential direction. Due to the form fit elements 17, 18, the segments Ito VII are not joined in a star shape to the fan wheel but in axial direction.
The neighboring segments I to VII are not only connected by form fit at the joining areas 15, 16 but also by an adhesive connection, a weld connection or the like, as has been explained in connection with the preceding embodiment. During the gluing or welding process, the segments I to VII that are contacting each other are advantageously strongly pressed against each other so that the connection at the joining areas 15, 16 is optimal. Neighboring segments can also be fixedly connected to each other by an adhesive or weld connection in the area of the form fit connection 17, 18.
In other embodiments according to the invention, form fit connections in circumferential direction can be realized also for axial fan wheels, diagonal fan wheels, or stators in a way equivalent to the described embodiment of
The fan wheel according to
The segments Ito VII are designed such that, in addition to the joining areas 15, 16 on cover ring 1* and hub ring 6*, also further joining areas 86 (
When neighboring segments I to VII are adjoined with their rims 4, 5, 9, 10, the vane parts 11a, 11b with their rims 19, 20 are contacting each other and form in this way the vane 11 which is hollow in this case. The rims 19 and 20 of neighboring segments which are contacting each other in the joined fan wheel form an additional joining area 86. In other respects, the vane 11 is of the same configuration as in the embodiments according to
When neighboring segments Ito VII are connected to each other by an adhesive connection, then the adhesive is not only provided in the joining areas 15, 16 of the rings but also in the joining area 86 of the vanes 11. In this way, a very large gluing surface is provided which ensures a strong connection between neighboring segments I to VII that is capable of withstanding even high loads. When neighboring segments to VII are connected to each other by a weld connection, in this embodiment the welding surface is enlarged by the area of the joining area 86 of the vane 11 which leads to an increased load capacity.
Since the vanes 11 are hollow, the fan wheel has a relatively minimal weight. Moreover, the hollow vanes 11 have the advantage that they enable in a simple way with respect to fluid mechanics the design of channels for targeted secondary flows.
After the joining process, edges, burrs, or the like can be present in the area of the joining areas 86 of the vanes 11; however, they can be easily removed in a conventional manner. The segments I to VII are identically embodied relative to each other and have, in the axial plan view, a center line 21 whose curvature course is identical to the curvature course of the rims 9, 10 in axial plan view. In this context, the width of the segment measured in circumferential direction decreases from the outer rim 2, 7 in the direction toward the inner rim 8 in such a way that the segment in the area of the outer rim 2, 7 has the greatest and in the area of the inner rim 8 the smallest circumferential width.
Due to the described configuration, the segments I to VII, as illustrated schematically with the aid of
Since
In contrast to the embodiment according to
The hollow configuration of the vane 11 is achieved in the injection mold by means of a sliding core. Due to this sliding core, the vane 11 in the area of the hub ring section 6 is open. In order to avoid noise development as well as also dirt deposits within the vane 11 in use of the fan wheel, the vane 11 is advantageously covered after the injection molding process or after the joining process of the complete fan wheel by a cover or the like or is filled with a material, for example, with a foamed material. The cover can be glued on, welded or in other suitable ways fastened to the hub ring section 6. The closure member is advantageously designed such that it is positioned with its exterior side flush with the exterior side of the hub ring section 1. In order to achieve this, a recess into which the closure member is introduced so as to be flush at the surface must be provided on the injection molded part in the area of the cavity on the hub ring section 6.
In the injection molding tool for producing the web-shaped reinforcement 22 two sliding cores are provided which are positioned at minimal spacing adjacent to each other so that the web 22 is formed between the sliding cores upon injection of the plastic material.
In the embodiments according to
The segments I to VII can also be designed such that the joining areas 15, 16 are positioned on the radial line 60 so that the angle α amounts to 0°.
The angle α can amount to up to approximately 80°, depending on the configuration of the segments I to VII. This angle range is independent of the manner in which the segments I to VII are connected to each other.
With the aid of
In an exemplary embodiment according to
An oppositely positioned rim 5, 10, 75 of a segment II is provided with at least one corresponding groove 26 in which the tongue 25 of the respective neighboring segment engages. The groove 26 is complementary to the respective tongue 25 and is positioned also approximately at half the thickness of the ring section 1, 6, 71. In the mounted position, the tongue 25 is resting areally against the side walls and the bottom of the groove 26. The joining area 15, 16, 85 that is formed by the two rims 4, 9, 74 and 5, 10, 75 of respective neighboring segments has a very thin layered design. Between the rims 4, 9, 74 and the rims 5, 10, 75, an adhesive is introduced into the joining area 15, 16, 85.
In the context of the invention, a tongue 25 is a projecting form fit part and a groove 26 is an at least approximately complementary recess in a rim 4, 9, 74 or 5, 10, 75.
The tongue 25 and the groove 26 are designed such that the ring sections 1, 6, 71 of the segments I, II abut each other so that no gap is formed at the exterior side and interior side of the joined rings 1*, 6*, 71*.
In order to be complete, it should be mentioned that switching of the features “groove” and “tongue” with respect to the rims 4, 5, 74 and 5, 10, 75 is also within the gist of the invention, which applies likewise also to the embodiments according to
In the embodiment according to
In both described embodiments according to the
In the embodiment according to
The joining area 15, 16, 85, viewed in section view, has end face areas 32, 33 that adjoin perpendicularly the inner side 30 as well as the exterior side 31 of the ring sections 1, 6, 71 and are connected to each other by a wall area 34. It extends advantageously at a minimal angle at a slant relative to the inner side 30 as well as the exterior side 31 of the segments I, II. The slantingly positioned wall area 34 facilitates joining of the neighboring segments I, II. Advantageously, the transitions between the end face areas 32, 33 and the wall area 34 are rounded in order to avoid crack formation.
In the end face areas 32, 33 and the wall area 34 an adhesive is applied so that the two segments I, II are reliably areally glued to each other at the joining area 15, 16, 85. The stepped configuration of the joining areas 15, 16, 85 is advantageously provided across their entire length.
The stepped configuration of the joining area 15, 16, 85 enables also a simple and problem-free joining process when producing the fan wheel.
In the embodiment according to
The cross section configurations in particular according to
The ring sections 1, 6, 71 have a wall thickness D which can be in the range between approximately 3 mm to approximately 12 mm. An advantageous range is between approximately 4 mm and approximately 8 mm. A particularly preferred wall thickness D is approximately 6 mm. The groove 26 has a depth t that is in the range of approximately (0.7 to 2.5)•D. Advantageously, the groove depth is approximately twice the wall thickness D.
The tongue 25 tapers in its cross section in the direction toward its free end 35. In this way, the tongue 25 is self-centering during the joining process. Moreover, this tapering of the cross section is advantageous in regard to strength. Near the free end 35, the tongue 25 has a thickness d2 while near the stop 98 it has the greater thickness d1. The tongue 25 is positioned with its side walls areally against the side walls of the groove 26. The end face 35 of the tongue 25 has minimal spacing relative to the bottom 36 of the groove 26. In this way, it is ensured that the two segments I, II can be joined such that the flanks 39 and 40 of the tongue 25 are resting areally on the groove and that at the inner side 30 as well as the exterior side 31 of the rings 1*, 6*, 71* no gaps are produced.
Due to the tapering of the cross section of the tongue 25, the cross section of the areas 37, 38 of the ring sections 1, 6, 71 surrounding the groove 26, viewed from the free end of the groove beginning in the area of the stop 98, is increasing constantly. In the area of the cross sectional thickness d2, the tongue 25 is only loaded minimally while the surrounding area 37, 38 of the groove of the segment II is greatly loaded. The corresponding thick area 37, 38 can therefore absorb this load safely.
In the cross section area d1, on the other hand, the tongue 25 is strongly loaded so that the surrounding area 37, 38 of the groove of the segment II can be correspondingly designed to be weak.
The wedge angle between the two flanks 39, 40 of the tongue 25 is advantageously in a range between approximately 0.5° and approximately 8°.
The transition between the flanks 39, 40 of the tongue 25 and the stop 98 is rounded by the radius R1 on the segment I. This radius R1 amounts to advantageously approximately (0.05 to 0.3)•D. The same value or a minimally greater value can be selected for the complementary radius R1 on segment II in order to reliably avoid a premature collision of the segments I and II in the area of R1 during the joining process. In this way, in the area of R1 a very small gap would be generated (not illustrated in
It is however advantageous to design this transition between the flanks 39, 40 and the stop 98 to be bionic, i.e., to provide no constant radius in this transition area. Advantageously, the curvature course of the transition is designed such that the radius of curvature at the stop 98 is small and increases continuously in the direction toward the flanks 39, 40. The bionic configuration of the transition has the advantage that in regard to the force flow from the tongue 25 into the ring section 1, 6, 71 of segment 1 it can be designed such a crack formation can be avoided.
The transition from the side walls of the groove 26 into the bottom side 36 of the groove 26 is rounded with the radius R2. It is advantageously (0.05 to 0.3)•D. In order to be able to ensure optimally the force flow, the rounded portion in the transition area is in particular advantageously bionically designed, i.e., no constant radius is provided. In this way, this rounded transition can be matched optimally to the loads that are occurring in use of the fan wheel in such a way that crack formations are avoided in any case. Advantageously, the curvature course of the transition is designed such that the curvature radius at the bottom 36 of the groove is small and becomes continuously greater in a pacing fashion in direction of the flanks 39, 40.
In the completely joined state, i.e., when the segments I and II abut each other at the stop 98, in the area of the flanks 39, 40 a pretension is advantageously already existing due to the compression of the segments I and II in the joining process. In this way, it is ensured that the flanks 39, 40 of the tongue 25 and the corresponding flanks of the groove 26 after joining are contacting each other without clearance.
When the segments I, II are connected to each other by laser welding in the joining area 15, 16, 85, a laser-absorbing liquid is applied onto the rims 4, 9, 74 and/or 5, 10, 75 prior to the joining process in an advantageous embodiment. After joining, during the welding process the laser light, which penetrates the specially employed material of the ring sections 1, 6, 71 which is transparent for the employed laser light, is converted in this area to heat so that neighboring material melts and is connected by material fusion. Since the absorbing liquid absorbs only a part of the laser light or becomes itself laser transparent due to the welding process, it is possible to weld with a single laser light source simultaneously in the area of both flanks 39 and 40 of the tongue 25.
When with a single laser light source welding is performed simultaneously in the area of both flanks 39 and 40 of the tongue 25, it can be advantageous when on both flanks 39 and 40 a liquid is applied, respectively, that absorbs laser light differently. On the flank 39 proximal to the laser light, a liquid can then be applied which absorbs laser light less strongly, while on the flank 40 which is remote from the laser light source a liquid is applied that absorbs laser light more strongly. In this way, a more uniform welding process relative to the flanks 39, 40 can be adjusted.
When such a welding process is performed, advantageously a special plastic material is employed as a material for the segments I to VII that is substantially transparent for the laser employed for welding. In an advantageous embodiment, the segments I-VII, in particular in the area of their rims 4, 9, 74 and 5, 10, 75 as well as their immediate environment, are not machined by cutting after the injection molding process because the surfaces otherwise have exceedingly laser light absorbing, laser light reflecting and/or laser light scattering properties. To the locations to be welded, substantially to the rims 4, 9, 74 and/or 5, 10, 75, a special liquid that absorbs laser light is applied in the described way prior to the welding process. It ensures that the energy of the laser light is converted precisely at the desired location to heat so that in this area the plastic material locally melts. This laser technology makes it possible to perform welding not only on the exterior surface of the ring 1*, 6*, 71* in the area of the inner side 30 and the exterior side 31, but also in internal areas of the joining areas 15, 16, 85 of the material of the fan wheel.
In an advantageous embodiment, the segments I-VII have a particularly smooth surface in the area of the inner side 31 and/or the exterior side 30 in immediate environment of the joining areas 15, 16, 85. This can be achieved, for example, by polishing the corresponding areas of the injection molding tool. In this way, the surfaces have to an even lesser degree laser light absorbing, laser light reflecting and/or laser light scattering properties; this has an advantageous effect in the laser welding process on injecting the laser light into the joining areas 15, 16, 85.
With the aid of
For this reason, the flank 39 is provided with a greater surface than the oppositely positioned flank 40. This has the result that the tongue 25, in contrast to the embodiments according to
The tongue 25 in cooperation with the groove 26 fulfills the function of self-centering of the segments I and II upon joining to the fan wheel. Due to the wedge angle between the two flanks 39, 40, the required compression force for welding is achieved in the area of the flank 39 upon joining. In other respects, the explanations provided in regard to the embodiment according to
The flank 39 adjoins at an obtuse angle the stop 98 while the flank 40 is approximately positioned at a right angle relative to the stop 98′ of the segment I or its rim section 1, 6, 71. Due to the asymmetric cross section configuration of the tongue 25 the two stops 98, 98′ are staggered relative to each other transverse to the thickness direction of the segments I, II, as is shown in
The stops 98, 98′ of the segment I form with the corresponding counter stops of the segment II the joining area 15, 16, 85.
In the same way, the bottom side 31 of the ring section 1, 6, 71 of the segment II in the joining area is also provided with a curved configuration so that the wall thickness in the joining area increases. In the area outside of the joining area, the segments I, II have the wall thickness D. Within the joining area, the wall thickness Dmax of the segments I, II is greater than the wall thickness D in the area outside of the joining area. Advantageously, the wall thickness Dmax is in the range of 1.05 to 1.2 times the wall thickness D.
The area 38 of the segment II that serves only for centering and for applying the contact pressure during the joining process, projects past the remaining course of the bottom side 31
The described configuration of the tongue and groove connection makes it possible to increase the contact pressure on the flank 39 of the tongue 25 in the joining process in that a pressure or force is applied one-sided to the top side 30 in the joining area 15, 16, 85. In this way, the segments I, II are clamped remote from the joining area 15, 16, 85.
In other respects, this embodiment is of the same configuration as the embodiment according to
The cover ring section 1 is upwardly curved at a spacing relative to the angled portion 41 such that the inner rim 3 has a greater axial spacing relative to the hub ring section 6 than the outer rim 2. The cover ring section 1 comprises the two rims 4, 5.
The hub ring section 6 has the curved outer rim 7 and the inner curved rim 8. At their two ends, the rims 7, 8 are connected to each other by the rims 9, 10. In the area of the outer rim 7, the hub ring section 6 is angled slightly opposite to the cover ring section 1. In other respects, the hub ring section 6 is of a planar configuration.
The rims 4, 9 are provided with tongues 25, as has already been described in connection with
Viewed in a plan view onto the segment, it has—with the exception of the configuration of the rims 4, 9, 74 and 5, 10, 75—the same contour shape as the segment according to
In the embodiment, the fan wheel has three straps 54 to 56. Depending on the size of the fan wheel, only one, two or more than three straps can be provided. The number of straps can be between 1 and 10. For the straps 54 to 56, preferably thermoplastic materials are used, such as polyamide (PA6, PA66, PA66/6, PAPA, PPA, PA 4.6, PA12), polyester (PBT, PET), polypropylene (PP), PPS, PES, PESU, PEEK, ABS, PC, ASA and the like. Preferably, a polyamide, a polypropylene or a polyester is used as material for the straps.
For the straps 54 to 56, also thermosetting resins can be used such as epoxide resin, urea resin or phenolic resin. Preferably, as a thermosetting resin an epoxide or phenolic resin system is used.
The straps 54 to 56 are advantageously reinforced with fibers, independent of whether they are comprised of a thermoplastic material or a thermosetting resin. As reinforcement fibers, glass, carbon, aramid, thermoplastic material (PET, PA) or natural fibers are conceivable such as flax, hemp, sisal, jute or coconut fiber.
The fibers are preferably endless fibers that can be produced simply and inexpensively. They can be introduced without problems into the plastic mass of the straps 54 to 56.
The straps 54 to 56 extend about the circumference of the fan wheel and are attached in a suitable way thereto. The straps 54 to 56 can be connected by welding to the fan wheel, for example. For the welding process, diode lasers but also other laser systems can be used. When the segments are manufactured of substantially laser transparent material, in an advantageous embodiment a laser absorbing liquid is applied prior to laser welding in the area of the straps 54 to 56 to be connected by welding. Ultrasonic welding can also be used for welding. Also, it is possible to produce a fixed connection between the straps and the fan wheel by friction in circumferential direction.
As a further possibility for connecting the straps 54 to 56 with the fan wheel, adhesive methods are also conceivable. As an adhesive, 1-component or 2-component adhesives are conceivable, such as polyurethane, acrylic, methacrylates or silicones, or solvent systems.
The connection between the straps 54 to 56 and the fan wheel can also be realized in that a curing thermosetting resin is wound onto them that cures after winding. In this way, a safe and fixed connection between the respective strap 54 to 56 and the fan wheel is achieved.
In the illustrated embodiment, the cover ring 1* is provided along its outer rim 2 with a circumferential extending groove 57 into which the strap 55 is placed. The groove 57 is thus present on the outer diameter of the cover ring 1*.
On the inner diameter of the cover ring 1* there is also a circumferentially extending groove 58 which receives the strap 54.
The hub ring 6* is provided on the outer diameter with a circumferentially extending groove 59 for the strap 56.
All grooves 57 to 59 are open in circumferential direction of the fan wheel. In this way, the straps 54 to 56 can be inserted easily into the grooves 57 to 59. The grooves 57 to 59 can be provided already during injection molding of the segments I to VII. Each of these segments comprises then in its cover ring section 1 or hub ring section 6 the corresponding ring groove section which upon joining of the segments I to VII form the ring grooves extending about the circumference of the fan wheel.
The groove side walls guide the straps 54 to 56 in axial direction so that they cannot slide off the fan wheel.
The straps 54 to 56 can be wound several times about the circumference of the fan wheel. Advantageously, the straps 54 to 56 are wound so many times about the circumference of the fan wheel that the grooves 57 to 59 are completely filled with the strap.
In principle, it is however sufficient when the respective strap 54 to 56 is wound only once about the circumference of the fan wheel wherein the two ends of the strap overlap each other. The overlap is advantageously at least 10 times the strap width up to maximally 20% of the circumference. For such a configuration, it is advantageous when the respective strap 54 to 56 has a width that corresponds to the width of the groove.
By means of the straps 54 to 56, the segments Ito VII are fixedly held together so that even at high loads, for example, at high rotary speeds and great diameters of the fan wheel, there is no danger that the segments become detached from each other.
When the fan wheels are provided with the described endless fiber reinforced straps 54 to 56, the fan wheels can be operated at higher rotary limit speeds.
The straps can also be provided on fan wheels that are not produced of segments but are of a one piece configuration. In such fan wheels, the straps 54 to 56, applied advantageously with pretension onto the fan wheel, also have an advantageous effect in particular in regard to increasing the rotary limit speed of the fan wheel.
The proportion of fibers in the straps 54 to 56 can advantageously be between 10 and 65 percent by volume, preferably between 25 and 60 percent by weight.
Also, axial fan wheels, diagonal fan wheels or stators can be reinforced advantageously in the described way with straps 54 to 56 on cover ring 1* and/or hub ring 6* and/or intermediate ring 76*.
In fan wheels which are manufactured of segments the occurrence of weld lines, as they inevitably occur during injection molding of complete wheels, can be completely avoided. Injection molding of individual segments, in particular of segments with only one vane 11, can be designed without generating weld lines. This point of weakness that is difficult to control can thus be avoided for fan wheel joined from segments. The strength of the joining areas 15, 16, 85 which is realized by gluing or welding connections can be achieved with the described elements of the invention.
The segments are each designed such that in the assembly process they can be joined respectively by an identical or similar movement. In
The fan wheel after the joining process can be postprocessed by cutting. This is, for example, important when in certain areas of the fan wheel a high true-running accuracy is required. This is, for example, expedient for the grooves 57 to 59 (
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 014 287.6 | Sep 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/001901 | 9/24/2015 | WO | 00 |
