Hood with mix axial / radial ventilator

Abstract

The invention relates to a steam extraction device with a suction region (2), a flow channel (3) which adjoins the suction region (2) in the flow direction and which is fluidically connected to same, and an outlet opening (4). The suction region cross-sectional area is larger than the flow channel cross-sectional area, and the outlet opening cross-sectional area is smaller than the flow channel cross-sectional area. The flow channel (3) is equipped with a diagonal ventilator (5) comprising an axial inlet (6) and an axial outlet (7), said diagonal ventilator suctioning air axially out of the flow channel (3) via the axial inlet (6) and blowing the air axially into the outlet opening (4) fluidically connected to the outlet (7) via the axial outlet (7).

Description

[0001] The invention relates to an extractor device with an intake area and a flow channel connected to the intake area in the direction of flow, which has an outlet opening for expelling the extracted air. A pipe is typically connected to the outlet opening, which can be led to an area outside the building.

[0002] Extractor hoods with an intake area, usually incorporating grease filters, and an adjoining air flow duct are known from the prior art. These typically use double-flow, forward-curved radial fans for intake.

[0003] However, the energy consumption and, depending on the design, the noise level of the extractor hoods are high with such a design.

[0004] The installation space available for the fan is extremely limited due to the flow duct, which is usually narrow for design reasons. In practice, the large intake area covers the cooker located beneath the extractor hood. The air drawn in via the intake area is channeled into the much narrower flow duct, so that a significant proportion of the flow from the intake area enters the flow duct from the side and is deflected for the first time in an axial direction, i.e. towards the center of the extractor duct. The radial fan draws air in radially from the flow duct and blows it out axially. The air is then deflected a second time at a right angle. Each deflection of the air volume flow results in further pressure losses and thus reduced efficiency, as the fan power must be adjusted.In addition, due to the limited space, the air is drawn in from a radial direction in an area close to the flow channel wall, which is aerodynamically unfavorable. Due to the limited space, the air is further accelerated during radial intake. The 90° deflection at the inlet to the radial fan results in significant pressure losses. The relevant prior art is known, for example, from US Pat. No. 5,983,888. A fan in a flow channel is disclosed in CH 213309. DE102012019419A1 also represents the technical background of the invention.

[0005] The invention is therefore based on the object of providing an extractor device that ensures lower power consumption and, optionally, reduced noise generation while maintaining the same extraction performance. These objects are achieved by an extractor device having the features of patent claim 1.

[0006] According to the invention, a fume extraction device is proposed with an intake area, a flow channel adjoining the intake area in the flow direction and fluidly connected to it, and an outlet opening. The intake area cross-sectional area is larger than the flow channel cross-sectional area and the outlet opening cross-sectional area is smaller than the flow channel cross-sectional area. A diagonal fan with an axial inlet and an axial outlet is arranged in the flow channel. During operation, the diagonal fan draws air axially from the flow channel via the axial inlet and expels it axially via the axial outlet into the outlet opening fluidly connected to the outlet.

[0007] The use of the diagonal fan in the flow duct advantageously results in a 40-60% reduction in pressure loss compared to conventional radial fans. Deflection losses and power consumption are reduced accordingly. Noise generation is also reduced, as the flow, once it enters the flow duct, does not change direction further until it reaches the outlet. The advantageous flow guidance in the extractor unit is made possible by the diagonal fan with an axial inlet and axial outlet.

[0008] In one design variant, the outlet cross-sectional area of ​​the diagonal fan corresponds to the outlet opening cross-sectional area. The diagonal fan is mounted with its outlet directly at the outlet opening to provide a flush transition between the outlet on the fan and the outlet opening on the flow duct. In practice, the diagonal fan is often connected directly to a duct connected to the outlet opening.

[0009] In one embodiment, the intake cross-sectional area is larger than the flow channel cross-sectional area by a factor of 2 to 20, preferably 3 to 10, and more preferably 4 to 6. In practice, frequently realized cross-sectional dimensions of the flow channel are, for example, 240 mm x 240 mm. In practice, outlet openings are usually set to a (pipe) diameter of 150 mm.

[0010] In an advantageous embodiment of the extractor fan, the diagonal fan has a diagonal fan wheel with a circumferential cover plate. The cover plate is arranged on the diagonal fan wheel on the side facing the inlet and covers the otherwise free axial fan blade edges. In a section facing the inlet, the cover plate runs parallel to an axial centerline, separate from the fan blades.

[0011] Furthermore, an inlet nozzle defining the axial inlet is arranged on the diagonal fan, with a flow cross-sectional area that decreases in the axial flow direction. It is advantageous to form the inlet nozzle as a single piece with the fan housing or to define part of the fan housing through the inlet nozzle.

[0012] In addition, the inlet nozzle extends axially into the diagonal fan impeller, forming an axial overlap area between the diagonal fan impeller and the inlet nozzle. For a compact design and optimal fluidic interaction, the inlet nozzle is surrounded at least in sections by the cover plate, particularly the section facing the inlet and running parallel to the axial centerline.

[0013] According to the invention, a flow-guiding inlet grille is arranged on the suction side of the inlet nozzle, which contributes in particular to reducing noise emissions and minimizing disturbing low-frequency sounds.

[0014] In an advantageous embodiment, the inlet nozzle has a maximum inlet flow cross-sectional area which determines a factor of 0.15 - 0.4 of the maximum flow channel cross-sectional area.

[0015] Furthermore, one embodiment of the extractor fan device provides for a guide vane defining the axial outlet, with a flow cross-sectional area increasing in the axial flow direction, to be arranged on the diagonal fan. The flow cross-sectional area preferably tapers to the outlet opening cross-sectional area. The guide vane is arranged downstream of the diagonal fan impeller in the axial flow direction and enables an increase in the axial outflow velocity. It thus contributes to increasing efficiency. It is also advantageous to form the guide vane as a single piece with the fan housing or to define part of the fan housing with the guide vane.

[0016] In one embodiment, the diagonal fan has a multi-part housing through which it is attached to the flow duct. In a two-part design, the first part of the housing is formed by the inlet nozzle, and the second part by the guide vane.

[0017] Furthermore, the invention includes the use of a diagonal fan in a fume extraction device as described above. The diagonal fan may comprise some or all of the disclosed features, as far as technically possible.

[0018] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. They show: Fig. 1 is an exemplary schematic representation of a prior art extractor device; Fig. 2 is a side sectional view of an extractor device according to the invention; Fig. 3 is a diagram illustrating the pressure curve versus the volume flow of the extractor device.

[0019] In Figure 1 1 schematically illustrates, by way of example, a prior art extractor hood 200 with a double-flow radial fan 210. The air flow generated by the radial fan 210 is indicated by arrows S, clearly showing that the air flow is deflected multiple times. In particular, a first 90° deflection occurs in the edge section between the flow duct and the radial fan 210 upon entering the intake section 211, and a second 90° deflection occurs within the radial fan 210 before the flow exits at the exhaust section 212.

[0020] Figure 2shows a fume extraction device 1 with an intake area 2, a flow-connected flow duct 3 with a square cross-section directly adjacent to the intake area 2 in the flow direction, and an outlet opening 4 that opens into a pipe 23. The diagonal fan 5 is mounted on the wall of the flow duct 3. The air flow generated by the diagonal fan 5 during operation is represented by the arrows P.

[0021] The intake area cross-sectional area of ​​the intake area 2 is many times larger than the flow channel cross-sectional area of ​​the flow channel 3, and the outlet opening cross-sectional area of ​​the outlet opening 4 is smaller than the flow channel cross-sectional area of ​​the flow channel 3. The diagonal fan 5 has the axial inlet 6 in the direction of the intake area 2, through which air is sucked axially from the flow channel 3 during operation and blown out directly into the pipe 23 via the axial outlet 7. The axial outlet 7 is directly connected to the outlet opening 4 and the pipe 23. The outlet cross-sectional area of ​​the outlet 7 of the diagonal fan 5 corresponds to the outlet opening cross-sectional area of ​​the outlet opening 4.

[0022] In the exemplary embodiment shown, the diagonal fan 5 has a structure with a motor 18 that is centrally mounted and fastened to a motor mount 20, around which the pressure chamber is guided. The motor 18 drives an upstream-mounted diagonal fan wheel 8 that has a circumferential cover disk 9 that partially covers axially exposed edges of the diagonal fan wheel blades 19. The cover disk 9 runs parallel to the axial centerline in the inlet section 21 and slopes outwards in the downstream direction, so that a flow chamber formed by the cover disk 9 and the base disk 28 merges essentially flush into the pressure chamber. The axial inlet 6 is formed by the inlet nozzle 10, the flow cross-sectional area of ​​which decreases in the axial flow direction.The inlet nozzle 10 has an inlet contour 24 that extends axially into the diagonal fan wheel 8 and forms the axial overlap region 11 with the inlet section 21 of the cover plate 9. A circumferential radial gap is provided between the inlet contour 24 of the inlet nozzle 10 and the inlet section 21 of the cover plate 9. The axial distance between the axial edges of the diagonal fan wheel blades 19 and the axial end of the inlet contour 24 of the inlet nozzle 10 is very small and corresponds to 10% of the axial extent of the inlet contour 24 of the inlet nozzle 10. The inlet nozzle 10 forms a maximum inlet flow cross-sectional area that corresponds to 40% of the flow channel cross-sectional area. Furthermore, the inlet nozzle 10 forms a first housing part of the diagonal fan 5. The second housing part, which is directly connected and fastened to the first housing part, is provided by the guide vane 12.The guide vane 12 forms the axial outlet 7 and has flow guide elements 22 that help determine the shape of the pressure chamber. These elements extend around the motor 18 to the outlet 7, thereby increasing the flow cross-sectional area in the axial flow direction to generate a Venturi effect. At the outlet 7, the outer housing wall of the guide vane 12, which guides the flow, runs parallel to the axial centerline.

[0023] Figure 3 shows the lower pressure loss when using the Figure 2 shown diagonal fan 5 in a fume extraction device 1 compared to the solutions known from the prior art, wherein the graphs 66 and 77 refer to a radial fan and a radial fan installed in a fume extraction device and the graphs 88 and 99 refer to a diagonal fan 5 and a diagonal fan 5 in accordance with Figure 2installed state. The two graphs 88 and 99 are significantly closer together, especially at higher flow rates.

[0024] The invention is not limited in its implementation to the preferred embodiments described above. Rather, a number of variants are conceivable, which utilize the presented solution even in fundamentally different designs. For example, a guide vane grille can be arranged upstream of the inlet nozzle, even if this is not shown in the figures. Furthermore, the diagonal fan can also be attached to the flow duct only axially and be spaced radially from the flow duct.

Claims

1. A fume extraction device with an intake region (2), a flow channel (3) which is adjacent and fluidly connected to the intake region (2) in the direction of flow, and an outlet opening (4), wherein a cross-sectional surface area of the intake region is larger than a cross-sectional surface area of a flow channel, and a cross-sectional surface area of an outlet opening is smaller than the cross-sectional surface area of a flow channel, wherein a diagonal fan (5) with an axial inlet (6) and an axial outlet (7) is arranged in the flow channel (3) which, during operation, sucks air axially out of the flow channel (3) via the axial inlet (6) and blows the same out axially via the axial outlet (7) into the outlet opening (4), which is fluidly connected to the outlet (7), wherein an inlet nozzle (10) which defines the axial inlet (6) and has a flow cross-sectional surface area that decreases in the axial direction of flow is arranged on the diagonal fan (5),wherein the inlet nozzle (10) extends in the axial direction into the diagonal fan wheel (8), whereby an axial overlapping region (11) is formed, and wherein a flow-guiding flow grid is arranged at the inlet nozzle (10).

2. The fume extraction device as set forth in claim 1, characterized in that a cross-sectional surface area of the outlet of the diagonal fan (5) corresponds to the cross-sectional surface area of the outlet opening.

3. The fume extraction device as set forth in claim 1 or 2, characterized in that the cross-sectional surface area of the intake is larger by a factor of from 2 to 20 than the cross-sectional surface area of the flow channel.

4. The fume extraction device as set forth in at least one of preceding claims, characterized in that the diagonal fan (5) has a diagonal fan wheel (8) with circumferential cover plate (9).

5. The fume extraction device as set forth in the preceding claim, characterized in that the cover plate (9) is arranged on the diagonal fan wheel (8) on a side pointing toward the inlet (6) of the diagonal fan (5).

6. The fume extraction device as set forth in one of the preceding claims, characterized in that the inlet nozzle (10) is surrounded at least in portions by the cover plate (9), whereby the inlet nozzle (10) and the cover plate (9) form the overlapping region (11).

7. The fume extraction device as set forth in at least one of the preceding claims, characterized in that the inlet nozzle (10) has an inlet flow cross-sectional surface area which determines the cross-sectional surface area of the flow channel by a factor of from 0.15 to 0.4.

8. The fume extraction device as set forth in at least one of the preceding claims, characterized in that a guide wheel (12) which defines the axial outlet (7) is arranged at the diagonal fan (5), with a housing wall portion of the guide wheel (12) extending at the outlet (7) parallel to an axial center line of the diagonal fan (5).

9. The fume extraction device as set forth in at least one of the preceding claims, characterized in that the diagonal fan (5) has a multipart housing which is attached to the flow channel (3).

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