GB1560117A

GB1560117A - Cross-flow blower

Info

Publication number: GB1560117A
Application number: GB4165176A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1975-10-08
Filing date: 1976-10-07
Publication date: 1980-01-30
Also published as: DE2545036A1; FR2327431A1; DE2545036B2

Description

(54) A CROSS-FLOW BLOWER (71) I, KURT ZENKNER, a German Citizen, of Husstrasse 5, Ettlingen, Germany do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention is concerned with cross-flow blowers.

According to the present invention there is provided a cross-flow blower comprising a casing having a guide body. which separates an inflow section from an outflow section and which is arranged to be spaced from the circumference of an impeller, and a guide plate which defines a spirally extending path in the outflow section, and which is so positioned that the impeller can be located between the guide plate and the guide body, wherein the guide body is at least in part a hollow body, said part comprising. on the side which is closest to the impeller circumference, a first wall section which is provided with a plurality of holes through which the delivered medium present may pass said first wall section being spaced from the impeller circumference to define therewith a gap of substantially constant width throughout an angular length of between 15 and 35 , and wherein a second wall section of said part of the guide body adjacent to said first wall section extends in the outflow section and has at least one opening through which, in operation, part of the medium may be recycled from the outflow section into the hollow part of the guide body and thence into the gap defined between the impeller circumference and the guide body, after passing through said first wall section.

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a sectional elevation of one embodiment of a cross-flow blower, in a schematic representation; Figs. la and ib are further schematic illustrations of the embodiment of Fig. 1; Figs. ic and id are schematic illustrations of modified cross-flow blowers; Fig. 2 is a side view of the blower of Fig. 1; Fig. 3 is an enlarged detail of a blower; and Figs. 4 to 7 are various details illustrating modified embodiments of the invention.

Referring to the drawings, a cross-flow blower comprises an impeller 1, a guide body 4 which separates an inflow section indicated by arrow 2 from an outflow section indicated by arrow 3, and a guide plate 5 which directs the outflow and terminates in a spiral end section. As with known blowers, the impeller is located between the guide plate 5 and the guide body 4.

The relevant characteristics of the guide body are: a) as shown in Fig. 1, it is a hollow body; b) its contour is approximately trapezoidal; c) the side which is closest to the impeller circumference includes a first wall section 6 which is located opposite to the impeller, and which is provided with numerous small holes so that medium may pass through this wall section 6 in the form of a flow which is defined neither in its direction nor in its intensity; d) the first wall section 6 is separated from the impeller circumference by a gap 7 which has a substantially constant width throughout its length, the gap extending concentrically with the impeller (the impeller centre is at 8), which has a depth corresponding substantially to the vane thickness, and which has an angular length of a = 15 to 35 ; e) a second wall section 10, adjacent to the first wall section 6, extends towards a blower outlet 9 on the pressure side of the guide body, and has at least one opening 11, through which part of the medium flowing towards the blower outlet 9 may be recycled from the pressure side into cavity 13 of the guide body as indicated by the arrows 12 and, passing through the wall section 6, may reach the gap between the impeller and the guide body as indicated by the arrows 14.

As shown in Figs. 1 and 3, the wall section 6 is curved in such a manner that this section extends parallel to the impeller circumference. The wall section 6 is defined by a perforated metal sheet with numerous small holes providing together a free cross-section of at least 30% which means that not more than 70% of the perforated metal sheet is "solid".

The flow passing through a perforated sheet with a large number of small holes adjusts itself completely to the requirements of the blower, because the perforations in the sheet enable the delivered medium to flow in various directions, depending on the purpose for which the blower is used, and on the location of the instantaneous working point of the blower. In this way the noise level is reduced to an extremely low value, the blower characteristic is stable despite the noise reduction, and the pressure is high, so that the blower actually ranges among the high pressure ventilators, whereby the pressure is just high enough to satisfy the requirements of the blower application. It is a particularly outstanding advantage of the new blower that the noise in the vicinity of the working point is almost completely eliminated.Apart from this the blower is characterised by a high efficiency.

As shown in Fig. 3, the gap 'S' between wall section 6 and the impeller circumference corresponds approximately to the vane depth t'. This is noteworthy because it is advisable to operate under an optimum noise level,' pressure characteristic; the more the gap width decreases, the more will the noise increase. A low sound pressure level may be brought about, as explained above, by providing holes 15 in the wall section 6, which are not directionally defined channels that might cause the flow to follow a given, clearly defined direction, but openings which enable the flow to emerge in the most widely varying directions, so that the flow follows the direction of the least resistance offered by the blower design.

As viewed in Fig. 1 from the inflow section 2, a radius 16 is shown to extend towards the commencement of the gap 7 between the impeller circumference and the wall section 6. while a radius 17 is directed towards the commencement of the guide plate 5, so that an angle + is formed which may measure between 120 and 1500.

Certain actions will now be described which are taken in order to influence the intensity of the return flow. The wall section 6 is connected, at the end of the gap 7, to the wall section 10 on the pressure side through a curved portion 18 whose radius 19 corresponds approximately to the vane depth. As explained above there must be at least one opening 11 in the wall section 10 on the pressure side to provide a passage. In the embodiment according to Figs. 1 - 1c and Fig.

7 the wall section 10 comprises a perforated metal sheet which has therefore a plurality of passages. In the embodiments of Figs. it, 4a and 6 the wall section comprises a partly perforated sheet. A single passage 11,11' is defined in each of the embodiments shown in Figs. 4 and 5, wherein the free cross-section of the respective passage may be varied using, for example, a pivoted flap 20 f ig. 4) or an adjustable slide 21 (Fig. 5) or the like.

The passages of the other embodiments may be closed at least partly, for example by means of an adjustable masking element in the form of a pivoted flap 22 (Fig. 6) which can be moved as indicated by the arrow double-headed 23 and is associated with the perforated sheet constituting the wall section 10' on the pressure side of the guide body.

This flap 22 may be substituted by an adjustable slide, the object being that the passage of the medium through the wall section is either impeded or completely prevented as indicated by the arrow 12'. In this manner it is possible to influence the intensity of the recycled flow and consequently also the blower-characteristic.

Apart from this, the wall section 10 on the pressure side of the guide body extends approximately parallel to the opposite section 24 of the guide plate.

The wall section 6, 6' (Fig. 7) of the guide body is substantially parallel to the impeller circumference, and a wall section 25 or 25' (Fig. 7) respectively extends from the wall section 6 at an angle defining the blower intake on one side. As shown in Figs. 1c and 1d and particularly Fig. 7, there is provided, between the wall section 6' and the section 25' which is non-apertured and does not include any perforation, a passage 26 through which the flow direction is as indicated by arrow 27. The passage 26 provides an additional means by which to influence the direction and intensity of the flow, all the more so when the cross-section of the passage 26 is adjustable. This may be achieved by means of an adjustable slide, an adjustable flap or the like, or by providing section 25' with a front portion 28, which is pivotal on a pin 29 extending parallel to the impeller shaft, to enable the portion 28 to be swivelled either towards the wall section 6' or away from it as indicated by the arrow 30. Thus the quantity of air flowing through the gap can be controlled, the flow intensity being increased for example when pressure requirements are high, or conversely, the rate of flow through the gap may be reduced when pressure requirements are moderate, or the flow may be stopped altogether, to avoid unnecessary energy losses otherwise inevitably caused by the flow through the gap.The wall section 25' may be provided with a member 31 which projects, relative to the wall section 6', into the gap between the guide body and the impeller and may contribute towards the directional control of the flow through the gap, causing it for example to follow the direction of a tangent or any other direction depending on requirements.

As explained above, the guide body 4 is substantially trapezoidal in shape, whereby the wall section 6 and the adjacent wall section 25 (Fig. 1) include an angle of 120 to 1500, the passage 26 being provided, if desired, at the apex 32. The wall section 6 and the adjacent wall section 10 include an angle of 50 to 75". The resulting form of the guide body has been confirmed to be very favourable, especially with regard to the pressure distribution but also in respect of the very low noise level. The wall section 10 of the guide body, or rather its tangent or the tangent origin, extends approximately tangentially to the impeller circumference, while the wall section 25, or rather its tangent or the tangent origin, intersects the impeller circumference.Apart from this the design is such that the wall section 6 is located in the second quadrant in a clockwise direction, of a co-ordinate system whose abscissa extends through the impeller pivot and the location of commencement of the guide plate at the inflow section (coinciding with the radius 17). This layout of the guide body is likewise favourable for the pressure characteristic and efficiency of the blower.

As shown in Fig. 1, the part of the cavity inside the guide body which in the embodiment shown in the illustrations is adjacent to the wall section 6, is filled with a soundabating material 35, for example mineral fibre, occupying the cavity part adjacent to the wall section 25 of the guide body. This sound-abating material is thereby contained between the solid wall section 25 which has no perforations, and a perforated sheet 36 which extends through the cavity at a given distance from the wall section 10 and includes, with the wall section 6, or rather its tangent or the tangent end-section, an angle y measuring approximately 90 , as it extends from the wall section 6 towards the side of the guide body which is remote from the impeller.The perforated sheet 36 enables acoustic waves to pass through the perforations as indicated by the arrow 37, so that they may be damped by the material 35 in the cavity. This sound-abatement has a stabilis ing effect on the flow conditions in general which is complemented by a damping effect in the region of discharge where the turbulence of the flow is reduced, lowering the sound pressure level corres pondingly.

The wall section 6 does not intimately sur round the impeller, but maintains a given spacing although it extends concentrically in relation to the impeller circumference.

Various modifications may be made without departing from the invention as claimed.

The cross-flow blower as described is characterised by an extremely low noise level during operation. It runs much more quietly than any known model of a similar design. In addition the blower, maintaining a stable pressure, has an efficiency which considerably exceeds that of known systems. The very satisfactory air delivery of the blower moreover makes it a valuable instrument in the generation of pressures high enough to satisfy the requirements of various practical applications.

WHAT I CLAIM IS: 1. A cross-flow blower comprising a casing having a guide body, which separates an inflow section from an outflow section and which is arranged to be spaced from the circumference of an impeller, and a guide plate which defines a spirally extending path in the outflow section, and which is so positioned that the impeller can be located between the guide plate and the guide body, wherein the guide body is at least in part a hollow body, said part comprising, on the side which is closest to the impeller circumference, a first wall section which is provided with a plurality of holes through which the delivered medium present may pass, said first wall section being spaced from the impeller circumference to define therewith a gap of substantially constant width throughout an angular length of between 15 and 35 , and wherein a second wall section of said part of the guide body, adjacent to said first wall section extends in the outflow section and has at least one opening through which, in operation, part of the medium may be recycled from the outflow section into the hollow part of the guide body and thence into the gap defined between the impeller circumference and the guide body, after passing through said first wall section.

2. A cross-flow blower according to claim 1, wherein said first wall section and/or said second wall section comprises a perforated sheet, the perforations of the sheet of said first wall section occupying in area at least 30% of the sheet surface such that not more than 70% of the sheet surface area is solid.

3. A cross-flow blower according to claim 1 or 2, wherein, when viewed from the inflow section, the radius of the impeller defining the commencement of the gap between the impeller circumference and the first wall section of the guide body, and the impeller radius defining the commencement of the guide plate include an angle of between 120 and 1500.

4. A cross-flow blower according to any of the claims 1 to 3, wherein, when viewed from the inflow section, at the end of the gap

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

25' may be provided with a member 31 which projects, relative to the wall section 6', into the gap between the guide body and the impeller and may contribute towards the directional control of the flow through the gap, causing it for example to follow the direction of a tangent or any other direction depending on requirements.

As explained above, the guide body 4 is substantially trapezoidal in shape, whereby the wall section 6 and the adjacent wall section 25 (Fig. 1) include an angle of 120 to 1500, the passage 26 being provided, if desired, at the apex 32. The wall section 6 and the adjacent wall section 10 include an angle of 50 to 75". The resulting form of the guide body has been confirmed to be very favourable, especially with regard to the pressure distribution but also in respect of the very low noise level. The wall section 10 of the guide body, or rather its tangent or the tangent origin, extends approximately tangentially to the impeller circumference, while the wall section 25, or rather its tangent or the tangent origin, intersects the impeller circumference.Apart from this the design is such that the wall section 6 is located in the second quadrant in a clockwise direction, of a co-ordinate system whose abscissa extends through the impeller pivot and the location of commencement of the guide plate at the inflow section (coinciding with the radius

17). This layout of the guide body is likewise favourable for the pressure characteristic and efficiency of the blower.

As shown in Fig. 1, the part of the cavity inside the guide body which in the embodiment shown in the illustrations is adjacent to the wall section 6, is filled with a soundabating material 35, for example mineral fibre, occupying the cavity part adjacent to the wall section 25 of the guide body. This sound-abating material is thereby contained between the solid wall section 25 which has no perforations, and a perforated sheet 36 which extends through the cavity at a given distance from the wall section 10 and includes, with the wall section 6, or rather its tangent or the tangent end-section, an angle y measuring approximately 90 , as it extends from the wall section 6 towards the side of the guide body which is remote from the impeller.The perforated sheet 36 enables acoustic waves to pass through the perforations as indicated by the arrow 37, so that they may be damped by the material 35 in the cavity. This sound-abatement has a stabilis ing effect on the flow conditions in general which is complemented by a damping effect in the region of discharge where the turbulence of the flow is reduced, lowering the sound pressure level corres pondingly.

The wall section 6 does not intimately sur round the impeller, but maintains a given spacing although it extends concentrically in relation to the impeller circumference.

Various modifications may be made without departing from the invention as claimed.

The cross-flow blower as described is characterised by an extremely low noise level during operation. It runs much more quietly than any known model of a similar design. In addition the blower, maintaining a stable pressure, has an efficiency which considerably exceeds that of known systems. The very satisfactory air delivery of the blower moreover makes it a valuable instrument in the generation of pressures high enough to satisfy the requirements of various practical applications.

WHAT I CLAIM IS: 1. A cross-flow blower comprising a casing having a guide body, which separates an inflow section from an outflow section and which is arranged to be spaced from the circumference of an impeller, and a guide plate which defines a spirally extending path in the outflow section, and which is so positioned that the impeller can be located between the guide plate and the guide body, wherein the guide body is at least in part a hollow body, said part comprising, on the side which is closest to the impeller circumference, a first wall section which is provided with a plurality of holes through which the delivered medium present may pass, said first wall section being spaced from the impeller circumference to define therewith a gap of substantially constant width throughout an angular length of between 15 and 35 , and wherein a second wall section of said part of the guide body, adjacent to said first wall section extends in the outflow section and has at least one opening through which, in operation, part of the medium may be recycled from the outflow section into the hollow part of the guide body and thence into the gap defined between the impeller circumference and the guide body, after passing through said first wall section.
2. A cross-flow blower according to claim 1, wherein said first wall section and/or said second wall section comprises a perforated sheet, the perforations of the sheet of said first wall section occupying in area at least 30% of the sheet surface such that not more than 70% of the sheet surface area is solid.
3. A cross-flow blower according to claim 1 or 2, wherein, when viewed from the inflow section, the radius of the impeller defining the commencement of the gap between the impeller circumference and the first wall section of the guide body, and the impeller radius defining the commencement of the guide plate include an angle of between 120 and 1500.
4. A cross-flow blower according to any of the claims 1 to 3, wherein, when viewed from the inflow section, at the end of the gap

between the impeller circumference and the guide body the first wall section is connected to the second wall section through a rounded section whose radius corresponds substantially to the radial length of the vanes.
5. A cross-flow blower according to any of the preceding claims, wherein an adjustable masking element is provided for varying or closing of the cross-section of the opening or openings in the second wall section.
6. A cross-flow blower according to claim 5, wherein said adjustable masking element is in the form of a pivotal flap.
7. A cross-flow blower according to claim 5, wherein said adjustable masking element is in the form of an adjustable slide.
8. A cross-flow blower according to any of the preceding claims, wherein the second wall section of the guide body extends substantially parallel to that part of the guide plate which is located directly opposite the second wall section.
9. A cross-flow blower according to any of the preceding claims, wherein the first wall section of the guide body is substantially parallel to the impeller circumference, and a third wall section of the guide body extends from the first wall section at an angle defining one side of the inflow section of the blower, comprises a non-apertured plate, and includes, relative to the first wall section, a member projecting towards the impeller.
10. A cross-flow blower according to claim 9, wherein a passage is defined between the first wall section and the third wall section, the cross-section of said passage being adjustable.
11. A cross-flow blower according to claim 10. wherein the passage cross-section is adjustable by means of an adjustable slide.
12. A cross-flow blower according to claim 10, wherein the passage cross-section is adjustable by means of a controlled flap.
13. A cross-flow blower according to claim 10, wherein an end part of the third wall section which is closest to the impeller is pivotal around a pin which is arranged to extend parallel to the impeller shaft, so as to be movable towards and away from the first wall section.
14. A cross-flow blower according to any of claims 9 to 13, wherein the first wall section and the third wall section include an angle of between 120 and 1500.
15. A cross-flow blower according to any of the preceding claims, wherein the first wall section and the second wall section include an angle of between 50 and 75".
16. A cross-flow blower according to any of the preceding claims, wherein the second wall section of the guide body extends in a plane which is substantially tangential to the impeller circumference.
17. A cross-flow blower according to any of the preceding claims, wherein the third wall section extends in a plane which intersects the impeller circumference.
18. A cross-flow blower according to any of the preceding claims, wherein the first wall section of the guide body is located in the second quadrant, as viewed in a clockwise direction on the impeller, of a co-ordinate system whose abscissa extends through the rotational axis of the impeller and the location of commencement of the guide plate at the inflow section.
19. A cross-flow blower according to any of the preceding claims, wherein that section of the hollow guide body adjacent to the inflow section is filled with a material having sound-abating properties.
20. A cross-flow blower according to claim 19, wherein said material is mineral fibre.
21. A cross-flow blower according to claim 19 or 20, wherein the material having sound-abating properties is contained between the third wall section and a perforated sheet of metal which is spaced from the second wall section and extends from the first wall section towards that side of the guide body which is remote from the impeller, at an angle of approximately 90".
22. A cross-flow blower according to any of the preceding claims, wherein the guide body has a substantially trapezoidal crosssection.
23. A cross-flow blower substantially as hereinbefore described with reference to the accompanying drawings.