EP0332078B1 - Regenerative blower - Google Patents

Description

The invention relates to an annular duct blower, which is intended in particular for conveying combustion air in heaters, such as vehicle heaters. Here, an annular channel is formed in a housing part of the annular channel blower, which has an inlet opening and an outlet opening and an interposed web-shaped interrupter. Furthermore, the ring channel blower has an impeller fitted with blades. For power regulation, a bypass channel can usually be provided between the inlet opening and the outlet opening, which can be adjusted by means of an adjusting screw.

Circular duct blowers of conventional design work relatively noisily, which is increasingly felt to be particularly unpleasant if, in accordance with the current efforts of the vehicle manufacturers, the passenger compartment is becoming ever quieter due to noise damping. In particular when using such a ring duct blower in a vehicle heater, the work of the same can be perceived in the passenger compartment of the vehicle.

From DE-A-2531740 an annular duct blower according to the preamble of claim 1 is known.

The covering section is designed as a kidney-shaped contour, the tip of which is directed against the flow in the middle of the channel. Starting from this tip, the covering section tapers towards the inner and outer edges of the ring channel. Furthermore, the covering section also has a tapering contour on both sides in the axial direction. The production of such a geometry proves to be complex, so that it can only be used economically with blowers of higher output.

In contrast, the subject matter of the present application is recognizably simpler for the same objective and thus allows more economical production.

A ring duct blower manufactured according to the features of claim 1 fulfills the above criteria. With the design according to the invention, the noise level can be reduced to such an extent that intake silencers can also be dispensed with in the case of ring duct blowers of lower output.

The section that emerges as essential according to the invention and covers the annular channel to achieve a gradual transition has the effect, in the inventive design of the annular channel blower, that there is no sudden pressure surge at the compression end of the annular channel by an abrupt transition from the annular channel to the outlet opening, but rather that in the Air conveyed in a ring channel gradually runs to the outlet opening. Thus, in the ring duct blower according to the invention, there is no whistle caused by a sudden pressure surge.

In order to avoid as far as possible sharp edges in the flow area with the air in the ring channel, the ends of the section covering the ring channel which transitions to the inner edge and / or to the outer edge of the ring channel are formed spirally.

According to a preferred embodiment of the invention, the section covering the ring channel is crescent-shaped or sail-shaped, and the tip of the section ends at the outer edge of the ring channel and points counter to the compression direction. With this design, the pressure differences between the inner edge and the outer edge of the ring channel are gradually reduced to the outlet without having to accept a loss in the performance of the ring channel blower.

In order to largely minimize internal flow resistances, particularly in the inlet area of such a ring channel blower, the part formed by the web-shaped interrupter of the ring channel blower is inclined at the inlet area in the direction of the ring channel base, provided with a rounded end edge and at least partially covers the inlet opening. This achieves a tangential inflow of the medium to be compressed, such as air, into the annular duct at the inlet area, so that one can also ensure a low-noise inflow, for example, of the air to be compressed in the annular duct blower and to be conveyed with the same.

In order to optimize the flow of the ring channel blower in terms of flow technology, the ring channel itself can be contoured at least in the inlet area in such a flow-favorable manner that, seen in the direction of flow, there is a gradual transition from the inlet opening to the base of the ring channel. As a result, the flow resistance in the inlet area of the ring duct blower is reduced in order to improve the efficiency of the ring duct blower.

According to an advantageous further embodiment according to the invention, for further fluidic optimization, the annular channel is contoured in such a flow-favorable manner in the area of the outlet that, seen in the direction of flow from the bottom of the annular channel, there is a gradual transition to the outlet opening. The flow resistance at the outlet area of the ring duct blower is thus also reduced in order to further improve the overall efficiency of the ring duct blower. These gradual transitions are expediently formed by roundings in the transition region or so-called transition radii, the term “transition radii” being understood not only in terms of area but also spatially, based on the shape of the ring channel.

liegt, wobei mit R der Radius des Außenrandes des Ringkanales und mit r der Radius des Innenrandes des Ringkanales bezeichnet ist, d.h. daß mit R  -  r die Breite des Ringkanales bezeichnet ist. Innerhalb dieses Größenbereiches kann der Verlauf des den Ringkanal abdeckenden Abschnitts weitgehend beliebig gewählt werden und es lassen sich auch Kurven dieses Bereichs miteinander kombinieren. Projiziert auf etwa die Mitte der Auslaßöffnung erstreckt sich somit der den Ringkanal abdeckende Abschnitt maximal etwa über einen Winkelbereich von 80° gesehen entgegen der Verdichtungsrichtung des Ringkanalgebläses. In Abhängigkeit von der Breite des Ringkanales gemäß vorstehender Definition können sich auch abgewandelte gekrümmte Begrenzungslinien bestimmen lassen, bei denen beispielsweise zwei oder mehr unterschiedliche Krümmungsradien vereinigt sind.The section covering the ring channel preferably has a curved limiting curve, the ++++ curvature of which is between 3R and $$\frac{\text{R - r}}{\text{2nd}}$$

lies, where R is the radius of the outer edge of the ring channel and r is the radius of the inner edge of the ring channel, ie R - r is the width of the ring channel. Within this size range, the course of the section covering the ring channel can largely be chosen as desired, and curves of this area can also be combined with one another. Projected onto approximately the center of the outlet opening, the section covering the ring channel thus extends at most approximately over an angular range of 80 °, counter to the compression direction of the ring channel blower. Depending on the width of the ring channel as defined above, modified curved boundary lines can also be determined, in which, for example, two or more different radii of curvature are combined.

In order to achieve the most favorable possible characteristic curve with regard to the total pressure difference and the volume flow in the ring duct blower according to the invention, and in particular not to have to accept a loss of performance, but rather to obtain a more favorable curve of the characteristic curve of such a ring duct blower, the aerodynamically contoured gradually extends Transition from the inlet opening to the bottom of the ring channel and / or from the bottom of the ring channel to the outlet opening in each case over a range of at most 20% of the length of the ring channel. This ensures that a sufficient length of the ring channel is available for the compression process to be carried out in the ring channel blower and for the conveying process.

Furthermore, the noise emission in the ring duct blower can surprisingly also be reduced by the fact that the bypass duct runs in an approximately perpendicular to the ring duct plane and between the inner edge and the outer edge of the annular channel extending partition between the inlet opening and the outlet opening is provided. This bypass duct is therefore not provided in the peripheral surface near the bottom of the ring duct, since an abrupt transition would also occur at this point when the bypass duct is open, but it is arranged in the ring duct blower according to the invention in the region of the outlet and provides a connection Outlet to inlet, which is as close as possible to the mouth opening of the outlet. Thus, the air flow has already been evened out and calmed down at this point, so that whistling noises are also avoided at this point.

The bypass channel is preferably designed as an elongated slot-shaped opening in the partition, so that it can be manufactured in a manner that is simple in terms of production technology. In the case of such a slot-shaped opening, the respective desired cross section can also be adjusted in a relatively large way.

In order to obtain a gradual transition from the outlet area to the inlet area also in the area of the bypass channel, the bypass channel, relative to the outer edge of the ring channel, is arranged inclined in the direction of the outlet opening in the partition. Generally speaking, it can thus be said that this bypass channel points obliquely towards the center of the housing part containing the ring channel. The bypass duct preferably encloses an acute angle with respect to the outer edge of the ring duct. The acute angle is suitably in a range from approximately 20 ° to approximately 45 °, and is preferably approximately 38 °. These angles of inclination have proven to be expedient on the basis of tests.

According to a preferred embodiment of the invention, the adjusting screw for adjusting the opening cross section of the bypass channel is also with respect to the outer wall of the the housing part containing the annular channel is arranged inclined, ie that the thread for adjusting the adjusting screw is cut into the housing part, approximately in the direct extension of the central axis of the elongated, slot-shaped opening in the partition. Thus, no sharp edges occur in the area of the bypass channel even when the bypass channel is fairly wide open, since the threads for the adjustment of the adjusting screw lie in the flow shadow of the air flow in the area of the bypass channel.

These angles of inclination are preferably approximately in the same range as the acute angle in the bypass channel, so that the angle of inclination is in a range of approximately 20 ° to approximately 45 ° and preferably the angle of inclination is approximately 38 °.

Fig. 1

eine Draufsicht auf das Gehäuseteil des Ringkanalgebläses, wobei aus Übersichtlichkeitsgründen das mit Schaufeln besetzte Laufrad desselben lediglich mit gebrochenen Linien schematisch angedeutet ist,

Fig. 2

eine Draufsicht auf die Außenseite des Gehäuseteils, d.h. auf den Einlaß- und Auslaßbereich desselben,

Fig. 3

eine Abwicklung längs der Linie III-III in Fig.2,

Fig. 4

eine Schnittansicht längs der Linie IV-IV in Fig. 1, und

Fig. 5

eine schematische Ansicht zur Verdeutlichung des Verlaufs der Begrenzungskante des den Ringkanal abdeckenden Abschnitt gemäß einer Ausbildungsform.

The invention is explained below using an example with reference to the accompanying drawings. It shows:

Fig. 1

3 shows a plan view of the housing part of the ring channel blower, the impeller of the rotor, which is equipped with blades, being only indicated schematically with broken lines, for reasons of clarity,

Fig. 2

a plan view of the outside of the housing part, ie on the inlet and outlet area of the same,

Fig. 3

a settlement along the line III-III in Fig.2,

Fig. 4

a sectional view taken along the line IV-IV in Fig. 1, and

Fig. 5

a schematic view to illustrate the course of the boundary edge of the portion covering the ring channel according to an embodiment.

In the figures of the drawing, identical or similar parts are provided with the same reference symbols.

Overall, 1 denotes the ring channel blower, which has a housing part 2 and an impeller 3 which is equipped with blades and which is indicated in broken lines in FIG. 1. The impeller 3 is driven in rotation by a motor, not shown, an electric motor. In the housing part 2, an annular channel 4 is formed with an approximately semicircular cross section. This semicircular cross section extends from an outer edge 5 over a deepest point of the ring channel 4, i.e. a so-called bottom 7 of the ring channel 4 to an inner edge 6, which, viewed in the axial direction of the housing part 2, lies approximately at the same height as the outer edge 5. Starting from the center point M of the housing part 2, the outer edge 5 of the ring channel 4 has a radius R and the inner edge 6 has a radius r. As entered with B in FIG. 1, the ring channel width B is equal to the difference between the radius R of the outer edge 5 and the radius r of the inner edge 6 and is thus: B = R - r. In the plan view shown in Fig. 1, 8 denotes an inlet opening of the ring channel blower 1 and 9 an outlet opening thereof. In Fig. 1, the outlet opening 9 can be seen in broken lines. The inlet opening 8 and the outlet opening 9 point approximately in the same direction, namely in the direction of the rear of the housing part 2, as can be seen from FIG. 2. Fresh air enters from the environment, for example, as combustion air, via an air inlet connection, not shown.

The direction of compaction is entered in FIG. 1 with an arrow. Starting from the outlet opening 9 or the outlet region assigned to it, the ring channel 4 is covered by a section 11 on the side facing the impeller 3 against the compression direction or upstream. This section 11 is crescent-shaped or sail-shaped in the example shown and it has a curved Limiting curve 12, which starts from the inner edge 6 of the ring channel 4 and ends in a kind of tip 13 on the outer edge 5 of the ring channel 4. The section 11 covering the ring channel 4 thus tapers continuously, starting from the inner edge 6 to the outer edge 5 of the ring channel 4. The curved boundary curve 12 is not sharp-edged, but is slightly chamfered or rounded. The transition 14 of the section 11 to the inner edge 6 is also expediently rounded and can be designed as a spiral seen in space. The transition 15 of the section 11 to the outer edge 5 is expediently also rounded or seen in a spiral shape in space.

liegt. Somit kann der Krümmungsradius im Bereich von dem Dreifachen des Radius R des Außenrandes 5, ausgehend als Maximalwert, bis etwa zu dem Minimalwert gewählt werden, der etwa gleich der halben Breite B des Ringkanals 4 ist.Measured starting from approximately the center of the outlet opening 9, this sail-shaped section 11 covering the annular channel 4 extends approximately over an angular range of 80 °. The curved limiting curve 12 shown is of course only to be understood as an example and, depending on the dimensions of the ring channel 4, this can have a curvature that is between 3R and $$\text{(}\frac{\text{R - r}}{\text{2nd}}\text{)}$$

lies. Thus, the radius of curvature in the range from three times the radius R of the outer edge 5, starting from the maximum value, can be selected up to approximately the minimum value, which is approximately equal to half the width B of the ring channel 4.

Between the inlet opening 8 and the outlet opening 9, a web-shaped interrupter 16 is provided which separates the inlet opening 8 from the outlet opening 9 and vice versa. The web-shaped interrupter 16 is designed in the ring duct blower 1 in such a way that a section 17 is obtained at the inlet area, the boundary edge 18 of which is approximately formed as a tangent to the circle of the inner edge 6. This section 17 is also inclined in relation to the plane stretched between the outer edge 5 and the inner edge 6 of the ring channel 4 in the direction of the base 7 of the ring channel 4. This inclination is only slight and can be approximately 12 °, for example. The section 17 partially covers the projection of the inlet opening 8 onto the ring channel 4, so that the air stream flowing in via the inlet opening 8 is already deflected such that it enters the ring channel 4 tangentially.

3, there are essentially no sharp transition edges in the area of the outlet, starting from the outlet opening 9 up to the annular channel 4. Rather, the transitions are rounded off with the help of transition radii. In connection with the section 11 covering the ring channel 4, the outlet area of the ring channel blower 1 is designed in such a way that the channel cross section, starting from the ring channel 4, extends gradually to the outlet opening 9 with rounded transitions. Similarly, it can also be seen from Fig. 3 that the entry area, starting from the inlet opening 8 to the annular channel 4 gradually narrows in cross section, the portion 17 of the web-shaped breaker 16 is designed in a corresponding manner at the inlet area, so that both the The inlet area as well as the outlet area of the ring channel blower 1 is contoured as a whole in terms of flow, ie that protruding sharp edges in the area of the air flow course are avoided. At all deflection areas, gradual, i.e. Rounded or with radii of curvature provided transitions, whereby the flow resistance is effectively reduced both in the inlet area and in the outlet area, and in particular effective noise emissions, such as whistling noises, are avoided, which previously led to a loud work of such a ring duct blower 1.

As can be seen in particular from the development according to FIG. 3, the outlet with the outlet opening 9 has a greater axial length than the inlet with the inlet opening 8. Thus, seen in the axial direction of the housing part 2, the outlet also has the outlet opening 9 over the inlet with the inlet opening 8 over. Of course, this need not necessarily be the case, but this form of training essentially depends on the design of the burner to be supplied with combustion air by means of the annular duct blower 1 and on the available installation space.

It is therefore essential in the design of the ring duct blower 1 according to the invention that the ring duct 4 is contoured in such a streamlined manner at least in the region of the inlet with the inlet opening 8 and optionally also in the region of the outlet with the outlet opening 9 that there is a gradual transition in the inflow direction or outflow direction from the inlet to the bottom 7 of the ring channel 4 or from the bottom 7 of the ring channel 4 to the outlet opening 9. These aerodynamically contoured sections of the ring channel 4, which form a gradual transition and on which the ring channel 4 does not yet have its maximum channel cross section, preferably each extend over a range of at most 20% of the length of the ring channel 4. Thus, there is still a sufficient length of the ring channel 4 available for the compression and promotion of air. The arrangement of a bypass duct 20 in the ring duct blower 1 according to the invention is explained in more detail below with reference to FIGS. 2 and 4. The bypass channel 20 is formed in a partition 21 which extends approximately in the axial direction of the housing part 2 and represents an extension of the web-shaped interrupter 16. Thus, the partition wall 21 extends approximately perpendicular to the plane of the ring channel 4 or to the plane passing through the base 7, and the partition wall 21 extends on the side of the housing part 2 facing away from the ring channel 4 approximately between the outer edge 5 and the inner edge 6 this partition wall 21 directly adjoins the inlet opening 8 and the outlet opening 9 lying side by side in the circumferential direction. The bypass channel 20 extends obliquely in this partition to the outer edge 5 of the ring channel 4 and thus closes an angle to the outer edge 5 a. The bypass channel 20 starts approximately from the height of the inlet opening 8 and extends in the form of an elongated, slot-shaped opening in the partition wall 21 in the direction of the outlet opening 9. The angle of the central axis of the elongated bypass channel 20 which is included in this case with the outer edge 5 of the annular channel 4 can be seen in are in a range from approximately 20 to approximately 45 ° and, according to a preferred embodiment, it is approximately 38 °. So it is an acute angle. In the extension of the bypass channel 20, a bore 22 is made in the housing part 2, which also extends at an angle to the outer edge 5 of the ring channel 4. This bore 22 is threaded and an adjusting screw 23 is inserted into the threaded bore 22 as an actuator. By means of this adjusting screw 23, the free passage cross section of the bypass channel 20 can be changed in a corresponding manner for power regulation. The set screw 23 is accessible from the outside 24 of the housing part 2. Thus, with the aid of a tool such as a screwdriver, the set screw 23 can be turned in a corresponding manner in order to set the desired free passage cross section of the bypass channel 20.

Since, in the invention, the bypass duct 20 is placed closer to the outlet opening 9 of the ring duct blower 1, the air flow emerging and compressed via the outlet region of the ring duct blower 1 has already calmed down and has been standardized with regard to its flow behavior, so that when a via the bypass duct 20 Direct connection from the outlet with the outlet opening 9 to the inlet with the inlet opening 8 is established, the swirling of the air flow is largely reduced and therefore a largely silent passage of the air from the outlet to the inlet is also achieved in the area of the bypass channel 20.

From the above description it follows that thanks to Measures according to the invention, in particular with regard to the section 11 covering the annular duct 4, starting from the outlet opening 9 against the compression direction, and the section 17 in the inlet region of the annular duct blower 1, a significant reduction in the noise emission of the annular duct blower 1 in the working state is achieved, which is approximately at least 25% compared to the noise emission of conventional ring duct blowers of this type can be reduced. Of course, the transitions 14, 15 to the inner wall 6 and to the outer wall 5 of the ring channel 4 as well as the streamlined contouring of the inlet area and the outlet area of the ring channel blower 1 as a whole contribute to this reduction in noise emissions. Furthermore, it has surprisingly been found that in the ring duct blower 1 according to the invention, despite a reduction in the effective length of the ring duct 4, there is nevertheless no loss in performance. Rather, it has been shown that larger total pressure difference values are obtained at the same speed of the ring duct blower 1 compared to the usual ring duct blowers, so that the usual working point for the total pressure difference at a predetermined volume flow at a much lower speed of the ring duct blower 1 according to the invention in Compared to the usual ring duct blowers. Thus, the ring duct blower 1 works more effectively and consumes less energy, so that an energy-saving operation of the ring duct blower 1 is obtained thanks to the design according to the invention.

hat. Hierdurch sind die oberen und unteren Grenzen des Bereichs der Krümmung definiert. Natürlich braucht die Begrenzungskante 12 keine einheitliche Krümmung zu haben, sondern es können auch Kombinationen aus wenigstens zwei unterschiedlichen Krümmungen verwirklicht werden, wobei zweckmäßigerweise die Auslegung derart getroffen ist, daß an den Übergängen zwischen den Kurvenabschnitten unterschiedliche Krümmungen keine scharfen Kanten vorhanden sind.As can be seen from FIG. 5, the area in which the curvature of the limiting curve 12 of the section 11 lies is illustrated with a hatched area. The upper and lower tolerance ranges with regard to changes from the family of curves in the above-mentioned ranges are indicated by border hatching. The curve labeled C₁ has a radius of 3R, while the curve labeled C₂ has a radius $$\frac{\text{R - r}}{\text{2nd}}$$

Has. This defines the upper and lower limits of the area of curvature. Of course, the boundary edge 12 need not have a uniform curvature, but combinations of at least two different curvatures can also be realized, the design advantageously being such that there are no sharp edges at the transitions between the curve sections different curvatures.

Claims (17)

1. A ring channel blower (1), in particular for combustion air conveyance in heating appliances, such as vehicle heaters, with a ring channel (4) in a housing part (2) which has an inlet opening (8) and an outlet opening (9), and also a web-like interrupter (16) situated between them, and with an impeller (3) provided with blades, wherein a section (11) covering the ring channel (4) and extending upstream from the outlet opening (9) extends on that side of the ring channel (4) nearest the impeller (3), characterised in that the section (11) covering the ring channel (4) tapers constantly upstream in the region of the outlet opening (9) extending from the inner edge (6) of the ring channel (4) to the outer edge (5) of the ring channel (4).

2. A ring channel blower according to Claim 1, characterised in that the ends of the section (11) covering the ring channel (4) and merging into the inner edge (6) and/or into the outer edge (5) of the ring channel (4) are spiral-shaped.

3. A ring channel blower according to Claim 1 or 2, characterised in that the section (11) covering the ring channel (4) is formed with a straight boundary edge which forms a tangent with the inner edge.

4. A ring channel blower according to any one of Claims 1 to 3, characterised in that the section (11) covering the ring channel (4) is sickle-shaped and its tip (13) ends at the outer edge (5) of the ring channel (4) and points counter to the compression direction.

5. A ring channel blower according to any one of the preceding Claims, characterised in that the part or section (17) formed by the web-like interrupter (16) is inclined at the inlet region in the direction of the bottom (7) of the ring channel (4), is provided with a rounded end edge and at least partly covers the inlet opening (8).

6. A ring channel blower according to any one of the preceding Claims, characterised in that the section (11) covering the ring channel (4) has a curved boundary edge (12) whose curvature is between about 3R and $$\frac{\text{R - r}}{\text{2}}$$

, in which R represents the radius of the outer edge (5) of the ring channel (4) and r represents the radius of the inner edge (6) of the ring channel (4), i.e. $$\frac{\text{R - r}}{\text{2}}$$

represents the half width (B) of the ring channel (4).

7. A ring channel blower according to Claim 6, characterised in that the curved boundary edge (12) represents a combination of curves of at least two different curvatures within the indicated range.

8. A ring channel blower according to Claim 6 or 7, characterised in that gradual transition, which is contoured to promote flow, extends from the inlet opening (8) to the bottom (7) of the ring channel (4) and/or from the bottom (7) of the ring channel (4) to the outlet opening (9) respectively over an area of at most 20% of the length of the ring channel (4).

9. A ring channel blower according to any one of the preceding Claims with a by-pass channel between the inlet opening and the outlet opening, which is adjustable by means of a set screw, characterised in that the by-pass channel (20) is provided in a partition (21) between the inlet opening (8) and the outlet opening (9), which partition extends approximately perpendicularly to the ring channel plane and which extends between the inner edge (6) and the outer edge (5) of the ring channel (4).

10. A ring channel blower according to Claim 9, characterised in that the by-pass channel (20) is in the form of an elongate slot-shaped opening in the partition (21).

11. A ring channel blower according to Claim 9 or 10, characterised in that, in relation to the outer edge (5) of the ring channel (4), the by-pass channel (20) is inclined towards the outlet opening (9) in the partition (21).

12. A ring channel blower according to Claim 11, characterised in that, in relation to the outer edge (5) of the ring channel (4), the by-pass channel (20) forms an acute angle.

13. A ring channel blower according to Claim 12, characterised in that the acute angle is in a range of about 20° to about 45°, preferably about 38°.

14. A ring channel blower according to any one of Claims 9 to 13, characterised in that the set screw (23) for adjusting the free passage cross-section of the by-pass channel (20) is inclined relative to the outer wall (24) of the housing part (2) containing the ring channel (4).

15. A ring channel blower according to Claim 14, characterised in that the angle of inclination is in a range of about 20° to about 45°, preferably about 38°.

16. A ring channel blower according to any one of the preceding Claims, characterised in that the ring channel (4) is contoured to promote flow, at least in the vicinity of the inlet, in such a way that, viewed in inflow direction, a gradual transition is provided from the inlet opening (8) into the bottom (7) of the ring channel (4).

17. A ring channel blower according to any one of the preceding Claims, characterised in that the ring channel (4) is contoured to promote flow, also in the vicinity of the outlet, in such a way that, viewed in flow direction, a gradual transition is provided from the the bottom (7) of the ring channel (4) into the outlet opening (9).

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