EP1741933B1 - Rotor and fabricating method thereof - Google Patents

Description

The invention relates to an impeller, in particular a plastic impeller for a drum rotor radial fan for the heating and air conditioning of a motor vehicle, according to the preamble of claim 1. The invention also relates to a method for producing an impeller.

Drum rotor centrifugal blowers, which are used for the promotion of air in automotive heaters or automotive air conditioning systems, are often operated at the lowest possible speed level. Here, the inflow to a subsequent heat exchanger should be as low as possible, the existing space, which is usually very cramped, should be used as flexible as possible. Because of the general conditions, axially expanded spiral housings and impellers with static pressure generation in the blade channel are generally used in this case. In this case, the blading are backward curved, radially ending or slightly curved forward and executed with or without slight profiling. The flow in the blade channel triggers hereby and remains detached up to the blade channel end. Due to this type of blading very high to high speeds are necessary depending on the operating point and type of blading. For acoustic reasons, in motor vehicle heaters or automotive air conditioning systems usually no rückwärtsgekrümmten blading is used.

Radial fans, which allow a low speed level, have a forward curved blading and achieve comparable operating points at much lower speeds. In the forward curved blading, the flow is greatly diverted and accelerated. This kinetic Energy is delayed in ideally designed, parallel-walled volute casings and converted into static pressure. Flow separation takes place at the blade channel inlet, and the flow arrives again at the blade channel end. Axially extended volute casings, which are favorable for the heat exchanger admission and build radially close, are usually meaningless with these blowers with forward curved blading, since it comes to efficiency losses.

In order to operate a drum rotor radial fan, which is used for the promotion of air, for example in motor vehicle heaters or automotive air conditioning systems, even at the lowest possible speeds, drum rotor radial blowers are known which have a forward curved blading. The blading is not or only slightly profiled. The blades are usually massively sprayed (see left part of Fig. 5 in which the flow pattern is shown in a blade channel in a conventional, non-profiled impeller, wherein on the suction side of the blades, a vortex formation can be seen).

Due to the flow separations in the blade channel, however, a profiling of the blades makes sense. In the production of plastic wheels it comes in injection molding relatively strong profiled wheels with relatively thick walls to warping and shrinkage.

The EP 1 035 330 A2 discloses an impeller for a tumbler radial fan for the heating and air conditioning of a motor vehicle having a plurality of blades, which have a supporting structure made of a first plastic and are formed of a plurality of layers.

It is therefore an object of the invention to provide an impeller that can be produced by injection molding without the above-mentioned problems.

It is also the object to provide a method for producing an impeller.
This object of the impeller is achieved by an impeller having the features of claim 1. The object of the method is achieved with the subject matter of claim 16. Advantageous embodiments are the subject of the dependent claims.

According to the invention, a plastic impeller for a drum rotor radial fan for the heating and air conditioning of a motor vehicle is provided, which has a plurality of blades, wherein the blades are formed by a supporting, preferably solid, structure, sprayed onto the at least partially a soft component or in the at least partially a soft component is injected. Here, the supporting structure is a first plastic which has sufficient strength, and the soft component is a second plastic which is softer. The second plastic is preferably a foamed plastic.

The maximum wall thickness of the supporting structure in the region of the blades is preferably 3 mm. With such a restriction of the wall thickness distortion and shrinkage can be safely avoided, however, by a suitable choice of material of the structure forming material, a sufficient strength of the impeller can be ensured. In addition, by an appropriate choice of material of the soft component, the weight of the impeller can be reduced, so that the blower is lighter overall. Furthermore, the soft component has an acoustically absorbing effect, so that the fan is somewhat quieter than corresponding fans without a soft component.

The soft component preferably forms at least in certain areas the profile of the blade, in particular in the strongly profiled part. Particularly preferably, a soft component layer is provided both on the suction and the pressure side, the ends of the blades are preferably soft component-free, whereby the soft component is additionally protected against damage during assembly.

According to a weight-saving embodiment, the blades are preferably at least partially formed as a hollow profile. In this case, webs may be formed in the hollow profiles to increase the rigidity. These are preferably closed on one side. In the case of a frame-side closure of the hollow profiles, the blades are preferably conically tapered on the frame side.

The blades are preferably formed on the impeller hub side of the motor side cylindrical and the frame side conical, wherein they taper in the frame direction. This ensures that, despite the strong profiling in connection with the overlap by the frame, a sufficient intake cross-section is available and there is no obstruction of the Ansaugquerschnitts.

The flow channel between two blades is preferably convergent on the inflow side and divergent on the outflow side, but other configurations are also possible. The convergent-divergent configuration of the impeller enables a substantially separation-free operation in the blade channel. It is accelerated by the strong curvature and sufficient thickness of the blade profile in the convergent region, the flow in the corresponding channel part and deflected in the direction of rotation of the impeller. In the subsequent, almost straight, divergent channel part, the flow is delayed, whereby the static pressure is increased.

The blade channel length ratio with an inflow-side convergent and outflow-divergent configuration of the flow channel is preferably between 0.1 and 0.9, in particular between 0.15 and 0.7, particularly preferably between 0.2 and 0.6. In this case, the channel taper in the convergent part of the blade channel is preferably between 0.030 and 0.2, in particular between 0.04 and 0.07, particularly preferably between 0.05 and 0.06. The channel widening in the divergent part of the blade channel is preferably between 0.05 and 0.17, in particular between 0.09 and 0.15, particularly preferably between 0.1 and 0.14.

The blades of the impeller are preferably formed strongly profiled. Particularly profiled blades are considered in particular, in which the ratio of profile thickness to total profile length is greater than 0.15, in particular greater than 0.2. Preferably, the pressure-side inlet angle between 30 ° and 90 °, more preferably between 35 ° and 80 °, and the suction-side inlet angle between 25 ° and 70 °, more preferably between 30 ° and 60 °, the pressure-side exit angle between 90 ° and 175 °, more preferably between 100 ° and 165 °, and the suction-side exit angle between 90 ° and 170 °, more preferably between 100 ° and 165 °, particularly preferably in the middle region, ie in particular +/- 10 ° around the mean of the respective ranges given above, in order to achieve an optimal flow pattern without detachment as well as an optimal efficiency and a low-noise operation.

The production of such an impeller is preferably carried out by means of plastic injection molding, wherein first the load-bearing structure injection molded from a first plastic and then or almost simultaneously injection molded at least a portion of the profiled trained blades of the impeller and / or a hollow profile by a second, softer plastic which is auf auf the supporting structure or injected into a formed by the supporting structure hollow profile.

Suitable materials for the supporting structure are in particular PA or PP, but also metals. The soft component surrounding the supporting structure, at least in some areas, is preferably in the form of a foamed plastic, in particular S-EPS. Also very suitable is PP-EPDM. In general, PUR foam, melamine foam, PE foam (use of propellant in the application), silicone foam or, with limitations, foamed elastomers can be used.

Fig. 1

eine perspektivische Ansicht eines erfindungsgemäßen Laufrads gemäß dem Ausführungsbeispiel,

Fig. 2

einen Schnitt durch eine Schaufel des Laufrads von Fig. 1,

Fig. 3a,

3bSchnitte durch Schaufelvarianten,

Fig. 4

eine Detailansicht eines Schnitts durch eine Schaufel zur Verdeutlichung einzelner Abmessungen,

Fig. 5

einen Schnitt durch ein herkömmliches, massiv ausgebildetes Laufrad mit durch Pfeilen dargestellten Strömungsgeschwindigkeiten im linken Teil der Fig. 5 und einen Schnitt durch ein vorwärtsgekrümmt profiliertes Laufrad gemäß der vorliegenden Erfindung im rechten Teil der Fig. 5,

Fig. 6

eine Draufsicht auf ein Laufrad,

Fig. 7

eine schematische Darstellung einer weiteren Schaufelvariante mit Darstellung der Querschnitte dreier Schnittebenen,

Fig. 8

einen schematisch dargestellten Schnitt in Längsrichtung durch eine Schaufel zur Verdeutlichung der Schaufelverjüngung,

Fig. 9

einen ausschnittsweisen Schnitt quer durch ein Laufrad mit verjüngten Schaufeln,

Fig. 10

einen Fig. 9 entsprechenden Schnitt zur Verdeutlichung der Verringerung der Schaufelquerschnittsfläche,

Fig. 11a-11d

schematische Darstellungen möglicher Verläufe von Schaufelverjüngungen,

Fig. 12

eine schematische Darstellung einer symmetrischen Verjüngung relativ zur Basisprofilskelettlinie der Schaufel,

Fig. 13

eine schematische Darstellung einer asymmetrischen Verjüngung relativ zur Basisprofilskelettlinie der Schaufel, und

Fig. 14

eine schematische Darstellung einer symmetrischasymmetrischen Verjüngung relativ zur Basisprofilskelettlinie der Schaufel.

In the following the invention will be explained with reference to an embodiment with several variants with reference to the drawings in detail. In the drawing show:

Fig. 1

a perspective view of an impeller according to the invention according to the embodiment,

Fig. 2

a section through a blade of the impeller of Fig. 1 .

Fig. 3a,

3b sections by blade variants,

Fig. 4

a detailed view of a section through a blade to illustrate individual dimensions,

Fig. 5

a section through a conventional massively trained impeller with flow velocities represented by arrows in the left part of the Fig. 5 and a section through a forward curved profiled impeller according to the present invention in the right part of Fig. 5 .

Fig. 6

a plan view of an impeller,

Fig. 7

a schematic representation of a further blade variant with representation of the cross sections of three sectional planes,

Fig. 8

a schematic longitudinal section through a blade to illustrate the blade taper,

Fig. 9

a sectional section across a wheel with tapered blades,

Fig. 10

one Fig. 9 corresponding section to illustrate the reduction of the blade cross-sectional area,

Fig. 11a-11d

schematic representations of possible courses of blade tapering,

Fig. 12

a schematic representation of a symmetrical taper relative to the base profile skeleton line of the blade,

Fig. 13

a schematic representation of an asymmetrical taper relative to the base profile skeleton line of the blade, and

Fig. 14

a schematic representation of a symmetric asymmetric taper relative to the base profile skeleton line of the blade.

A drum-type centrifugal fan used for the conveyance of air in an automotive air conditioner includes an impeller 1 having a Ring of blades 2, wherein between each two blades 2, a blade channel 3 is formed. The impeller 1 is mounted on a fan motor shaft (not shown) in a known manner. On the suction side, the impeller 1 is partially covered by the frame, which is part of the spiral housing. The frame opening for the air intake is in Fig. 6 implied

The blades 2 are formed strongly profiled, the flow channel 3 is convergent in the inlet region 4 and divergent in the exit region 5 (see. Fig. 4 ). The pressure side DS of the blades 2 is concave in the inlet region 4, optionally to the outlet region 5, and the suction side SS of the blades 2 is convex in the inlet region 4 and straight in the outlet region 5, the blade thickness d having its maximum in the convergent region.

In order to avoid the known problems in the production of highly profiled blades, the blades 2 consist of a structure 6, which in the present case is made of a solid plastic, and has sufficient strength for the expected loads, as well as a sprayed onto the structure 6 layer 7 of a soft component which forms the profile in the strongly profiled region of the blade 2. In this case, the thickness of the structure 6 is at most 3 mm, so that in the production of the structure 6 no problems with regard to distortion or shrinkage occur. In addition, this thickness usually suffices for sufficient rigidity of the blade 2. The sprayed-on layer 7 serves only for profiling and, apart from the requirement that it can not be compressed by the air to be conveyed, has no supporting function. In this case, the molded layer 7 on its outer side 8 also have a skin or a coating, wherein the coating, in particular to simplify the production, optionally also the entire blades 2 or the entire impeller 1 can cover.

The supporting structure 6 is slightly tapered in the region of the blade 2 covered by the soft component, the taper being gradual. The outer contour is not affected by the transition from supporting structure 6 to soft component.

The supporting structure 6 according to the present embodiment consists of PA, the soft component of PP-EPDM.

In the FIGS. 3a and 3b Variants of the blade 2 are shown, in the present case in these blades, the structure 6 itself forms the profile, for which it is designed as a hollow profile, in the case of the second variant with a stiffening web. In the interior of the hollow profile, a soft component corresponding to the molded layer 7 may be provided, in particular for rigidity reasons. Also, in individual areas, an externally molded layer may be provided according to the embodiment described above. Also in this case, the thickness of the structure is at most 3 mm, so that no distortion or shrinkage occurs during manufacture.

By way of the position of the supporting structure 6 within the profile, the thickness of the soft component on the blade suction and pressure side can be adjusted such that only minimal, non-flow-influencing deformation of the soft component, in particular on the blade pressure side, occurs during blower operation.

Furthermore, in such a profiled blade design, as in Fig. 5 , Right part is clearly visible, no vortex formation on the suction side of the blade 2, so that the flow is good. This leads to an improvement in the efficiency eta (cf Fig. 5 in each case, the flow profile and the corresponding efficiency at the optimal operating point of the corresponding blower is shown).

und $$\mathrm{Lkv}=\mathrm{Lgekrdiv}/\mathrm{Lgekrges}$$

The following geometries are particularly suitable for a convergent-divergent blade channel, in particular for heavily profiled blades, ie at d / lges greater than 0.15, in particular greater than 0.2, where d denotes the profile thickness and lges the total profile length (measured straight):
The blade channel length ratio Lkv is preferably between 0.1 and 0.9. Here Lgekrges refers to the length of the entire curved blade channel, Lgekrdiv the length of the divergent part of the curved blade channel and Lgekrkonv the length of the convergent part of the curved blade channel, wherein $$\mathrm{Lgekrges}=\mathrm{Lgekrdiv}+\mathrm{Lgekrkonv}$$

and $$\mathrm{Lkv}=\mathrm{Lgekrdiv}/\mathrm{Lgekrges}$$

liegt vorzugsweise zwischen 0,030 und 0,200. Dabei ist A1 die Strömungskanalbreite am Eintritt und A2 die Strömungskanalbreite am engsten Querschnitt.The channel taper Kverkonv in the convergent part of the blade channel, which results from $$\mathrm{Kverkonv}=\left(\mathrm{A}1-\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">A</figure-callout>}2\right)/\mathrm{Lgekrkonv}$$

is preferably between 0.030 and 0.200. Here A1 is the flow channel width at the inlet and A2 is the flow channel width at the narrowest cross section.

liegt vorzugsweise zwischen 0,05 und 0,17. Dabei ist A3 die Strömungskanalbreite am Austritt.The channel extension Kerwdiv in the divergent part of the blade channel, which results from $$\mathrm{Kerwdiv}=\left(\mathrm{A}3-\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">A</figure-callout>}2\right)/\mathrm{Lgekrdiv}$$

is preferably between 0.05 and 0.17. Where A3 is the flow channel width at the exit.

Here, the inlet-side inlet angle beta1DS is between 30 ° and 90 ° and the inlet-side inlet angle beta1SS is between 25 ° and 70 °. The pressure-side outlet angle beta2DS between 90 ° and 175 ° and the outlet-side outlet angle beta2SS between 90 ° and 170 °.

The aforementioned angular ranges for beta1DS, beta1SS, beta2DS and beta2SS are also particularly suitable in the case of a divergent-convergent blade channel shape and a convergent blade channel shape.

As a result of a highly profiled design of the blades 2 in conjunction with the inlet opening (only about 1/3 of the blading is not covered by the frame) may occur at high mass flows to obstructions in the inlet area, as in Fig. 6 indicated. These can lead to a reduction in the efficiency. For this reason, according to a further variant, the blades 2 are formed over their length or at least one or more parts thereof parallel to the axis of rotation with a different cross section. The cross section is on the inlet side, as in Fig. 7 shown, impeller hub side cylindrical (the impeller hub side is in Fig. 1 provided with the reference numeral 9) with a Ausformschräge and zargenseitig conically tapered in the longitudinal direction of the frame towards.

The FIGS. 8 to 10 show a further variant with tapering in the direction of the inflow side blades 2. Here, the blades over a large part of the blade length in the direction of the axis of rotation seen a constant cross-section. Only in the last quarter, the cross-section of the blades decreases and both in the longitudinal profile direction, wherein the inner diameter dinenn diverj up to a tapered inner diameter enlarged, but the outer diameter remains constant as well as in the thickness direction. For better clarification of the profile change is in Fig. 9 the skeleton line of the base profile is indicated by a star-dashed line. The course of the taper over the entire blade length is in Fig. 8 shown. The total blade length is hereby called Slgesamt, the part of the blade length, in which the inner diameter is increased, is denoted by Slverj. The inner diameter diverj takes this, as from Fig. 8 seen in the last quarter of the blade length too. The representation of Fig. 8 in terms of profile length is not to scale.

In general, ratios of blade length tapered to total blade length (slver / total) are from 0.1 to 0.7, preferably from 0.15 to 0.5, and more preferably from 0.20 to 0.25.

beträgt in der Regel 0,01 bis 0,2, vorzugsweise 0,02 bis 0,1 und insbesondere bevorzugt 0,04 bis 0,07, wobei sich Dnenn und Dverjüngt ergeben aus $$\mathrm{Dnenn}=\mathrm{dinenn}/\mathrm{da}$$

und $$\mathrm{Dverjüngt}=\mathrm{diverj}/\mathrm{da}$$

The diameter ratio DV resulting from the following equation $$\mathrm{DV}=\left(\mathrm{dnom}-\mathrm{Dverjüngt}\right)/\mathrm{dnom}$$

is usually 0.01 to 0.2, preferably 0.02 to 0.1 and particularly preferably 0.04 to 0.07, wherein Dnenn and D tapered result from $$\mathrm{dnom}=\mathrm{dinenn}/\mathrm{there}$$

and $$\mathrm{Dverjüngt}=\mathrm{diverj}/\mathrm{there}$$

Here, there is the blade outer diameter, dinenn the nominal inner diameter of the blades and diverj the tapered inner diameter of the blades.

wobei Anenn die Querschnittsfläche im nicht verjüngten Bereich ist, und im Folgenden auch als Basisprofil bezeichnet wird, und Averj die Querschnittsfläche im (am meisten) verjüngten Bereich ist. Die Veränderung des Schaufelprofils ist besonders gut aus Fig. 10 ersichtlich. Im Allgemeinen, d.h. nicht explizit auf die vorliegende Variante bezogen, liegt die relative Querschnittsflächenabnahme AV im Bereich von 0,1 bis 0,90, insbesondere von 0,2 bis 0,8 und besonders bevorzugt von 0,3 bis 0,7.In addition to the blade profile length, the thickness of the blade profile is also reduced, so that the cross-sectional area of the blade profile also decreases in the tapered region. The relative cross-sectional area decrease results $$\mathrm{AV}=\left(\mathrm{Anenn}-\mathrm{Averj}\right)/\mathrm{Anenn}$$

where Anenn is the cross-sectional area in the non-tapered area, hereinafter also referred to as base profile, and Averj is the cross-sectional area in the (most) tapered area. The change in the blade profile is particularly good Fig. 10 seen. In general, ie, not explicitly related to the present variant, the relative cross-sectional area decrease ΔV is in the range from 0.1 to 0.90, in particular from 0.2 to 0.8 and particularly preferably from 0.3 to 0.7.

Other variations in terms of the course of the taper are exemplary in the FIGS. 11a to 11d shown, where Fig. 11a a convex rejuvenation course, Fig. 11b a concave rejuvenation process, Fig. 11c a linear rejuvenation course and Fig. 11d show a simply graduated rejuvenation course. Any combination as well as a possibly multi-graded rejuvenation course are possible.

The FIGS. 12 to 14 show variants with respect to the shape of the taper of the blade profile in the direction of the inflow side. The course of the taper can, for example, according to the representation of FIGS. 11a to 11d respectively. For better clarification of the profile change is in the FIGS. 12 to 14 the skeleton line of the respective base profile is indicated by a star-dashed line.

The taper relative to the base profile may be symmetrical to the skeleton line, as in FIG Fig. 12 represented by the dashed line in a blade 2 on the suction side. The taper relative to the base profile can also be asymmetric to the skeleton line as in Fig. 13 represented in a blade 2 by the dotted line on the suction side. The rejuvenation can also be partially symmetrical and partially asymmetrical to the skeleton line, as in the FIGS. 12 to 14 is shown by solid lines and is apparent when comparing the solid lines with respect to the dashed or dotted line.

Generally, it should be noted that the channel shape in the tapered portion of the blading may be both convergent, convergent-divergent or divergent.

Particularly preferably, the entry and exit angles in the tapered blade part deviate from those in the region of the base profile, i. in the part with a constant cross section, from which results in an aerodynamic distortion of the blade profile. However, the angles may also remain constant or at least substantially constant.

If the blades are designed as (partial) hollow profiles, then they may be open or closed on the frame side.

According to a variant not shown in the drawing, an at least partial cover plate may also be present on the frame side.

Claims (16)

1. An impeller for a drum rotor radial fan for the heating and air-conditioning of a motor vehicle, with a plurality of vanes (2), having a supporting structure (6) of a first plastic, characterised in that a soft component of a second plastic is injected onto the supporting structure (6) of the vane (2), at least in areas, or a soft component of a second plastic is injected into the supporting structure (6) of the vane (2), at least in areas.
2. The impeller according to claim 1, characterised in that the maximum massive wall thickness of the supporting structure (6) in the area of the vanes is 3 mm.
3. The impeller according to claim 1 or 2, characterised in that the soft component forms the profile of the vane (2) at least in areas.
4. The impeller according to one of the preceding claims, characterised in that the vanes are formed as a hollow profile at least in areas.
5. The impeller according to claim 4, characterised in that webs are provided in the vanes formed in a hollow manner.
6. The impeller according to claim 4 or 5, characterised in that the vanes formed as a hollow profile are closed at one side.
7. The impeller according to one of claims 4 to 6, characterised in that a soft component is injected into the interior of the hollow profile.
8. The impeller according to one of the preceding claims, characterised in that the impeller (1) is produced by means of two-component plastic injection moulding.
9. The impeller according to one of the preceding claims, characterised in that the vane profile tapers at least partially in the direction to the frame.
10. The impeller according to one of the preceding claims, characterised in that the vanes (2) are formed in a cylindrical manner on the side of the impeller hub and are formed in a conical manner on the side of the frame.
11. The impeller according to one of the preceding claims, characterised in that the flow channel (3) between two vanes (2) is formed in a convergent manner on the inflow side and in a divergent manner on the outflow side.
12. The impeller according to one of the preceding claims, characterised in that the vane channel length ratio (Lkv) is between 0.2 and 0.6.
13. The impeller according to one of the preceding claims, characterised in that the channel tapering (Kverkonv) in the convergent part of the vane channel (3) is between 0.030 and 0.20.
14. The impeller according to one of the preceding claims, characterised in that the channel expansion (Kerwdiv) in the divergent part of the vane channel is between 0.05 and 0.17.
15. The impeller according to one of the preceding claims, characterised in that the vanes (2) of the impeller (1) are formed such that they are highly profiled, wherein the pressure-side entrance angle (beta1DS) is between 30° and 90° and the suction-side entrance angle (beta1SS) is between 25° and 70°, the pressure-side exit angle (beta2DS) is between 90° and 175° and the suction-side exit angle (beta2SS) is between 90° and 170°.
16. A method for producing an impeller (1) according to one of claims 1 to 15, characterised in that the supporting structure (6) is injection-moulded out of a first plastic first and then or nearly at the same time at least one part of the vanes (2) of the impeller (1) formed in a profiled manner are injection-moulded through a second, softer plastic which is injected onto the supporting structure (6) or injected into a hollow profile formed by the supporting structure.

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