CN101410627B

CN101410627B - Improved impeller and fan

Info

Publication number: CN101410627B
Application number: CN2007800104155A
Authority: CN
Inventors: 考林·布鲁姆
Original assignee: Applied Energy Products Ltd
Current assignee: Applied Energy Products Ltd
Priority date: 2006-01-25
Filing date: 2007-01-19
Publication date: 2010-06-02
Anticipated expiration: 2027-01-19
Also published as: AU2007209185A1; AU2007209185B2; CN101410627A; EP1979623A1; GB0601449D0; US20100189557A1; ES2327291T3; DE602007001234D1; WO2007085798A1; ZA200806463B; ATE433054T1; EP1979623B1; NZ569987A

Abstract

An impeller for a fan, which impeller comprises a hub and one or more blades, wherein at least one blade has a radially inner portion which is aerofoil in section and a centrifugal accelerator portion which extends radially outwardly from the aerofoil portion. The aerofoil portion has a greater angle of attack than the accelerator portion.

Description

Improved impeller and fan

Technical field

The present invention relates to a kind of improved impeller that is used for fan, relate in particular to the impeller of a kind of draught fan or blower, more specifically is to be used for family expenses and/or commercial fan, and this fan is mainly used in pipeline, ventilation duct or is used for the portion within the walls of building.The invention still further relates to a kind of fan that comprises this impeller.

Background technique

In the draught fan that prior art provides, the air stream by fan is centrifugal.In this fan, the center has the high turbulent flow that the rotation by blade causes, this brings high loss and poor efficiency.Its reason is that the center whirlpool has reduced the available inlet area that feeds fan effectively, so that have high-speed air in the outer edge of inlet, and to adapt to the pressure gradient that fan causes.Consider the flow profile that enters fan, another shortcoming of present centrifugal cutter is: the minimum clearance for the capacity air that enters inlet is half of diameter of fan normally.

The high pressure gradients of conventional centrifugal cutter and other performance characteristic bring any problem for conventional operation, are used for holding required flowing because the inlet opening can design.Yet when the centrifugal cutter of routine is set at narrow and small inlet and discharges in the ventilation duct, efficient will reduce greatly.

Also shortcoming of conventional fan is that caused inner vortex can have influence on the efficient that Pressure characteristics also further reduces fan when using embedded centrifugal cutter.Thereby be necessary in pipeline, to provide a kind of straightener or baffle plate to prevent the formation of this whirlpool.Straightener also is used for reducing discharge loss (dump loss) in box centrifugal cutter.

The fan of a kind of providing " mixed flow " is provided prior art; Air stream by fan comprises axial component and centrifugal component.Yet in existing " mixed flow " fan, very low of the axial component of air stream accounts for 5% magnitude of total air stream, and the air stream of remainder is centrifugal.Therefore, existing mixed flow fan shows and the conventional the same shortcoming of centrifugal cutter.

And conventional mixed flow fan comprises having the recurvate centrifugal of dish-shaped backboard, makes impeller the flow performance of spirality or scroll can be applied on the fluid that leaves fan.Like this, owing to produced undesirable tangent line stream (rather than radial flow), therefore lost efficient in the downstream of fan.

Summary of the invention

The purpose of this invention is to provide a kind of fan, this fan reduces or has avoided basically the shortcoming of said fans.

An also purpose of the present invention provides a kind of fan, and this fan is compared with the draught fan of routine, can be installed in the ventilation duct with narrow and small relatively inlet and discharge area, and this fan has the shallow relatively degree of depth than the fan of routine.

An also purpose of the present invention provides a kind of fan, and this fan passes through the air of relative high power capacity by narrow and small ventilation duct.

The invention provides a kind of impeller of fan, this impeller comprises wheel hub and one or more blade, and described at least one blade has: the inner radial part, and the section of described inner radial part is wing (aerofoil); With the centrifugation accelerates part, this part extends radially outward from airfoil-shaped portion, and wherein said airfoil-shaped portion has than the bigger angle of attack of centrifugation accelerates part.

The angle of attack is defined as the front portion of blade and the moving direction angle between the two of blade.

Impeller of the present invention has the wing and part centrifugal fan characteristics of part, thereby can draw in more substantial air towards the center of fan than the impeller of routine.This impeller provides the more uniform flow profile that enters the air of fan, avoids towards the turbulent flow at center with towards the high-flow area of fan inlet neighboring area.According to the present invention, airfoil-shaped portion moves in the mode of axial impeller, and it is radially outside that accelerating part drives air simultaneously, and axial like this and radial members is included in " combination " flow impellers.

In one embodiment, inner radial or airfoil-shaped portion are spiral.Spirality shaft portion at impeller root place applies radial effect power roughly and feeds air into fan, forces air radially outwards to flow out.Thereby air is forced outward to long path lateral accelerating part.

Preferably, vane curvature can increase towards the spin axis or the center of impeller.Typically, the angle of the spin axis of blade and impeller is in blade central part office maximum.Thereby the angle of attack of blade is in the accelerating part maximum.

In a preferred embodiment, the angle of attack of blade reduces at airfoil-shaped portion, and is typical, and the angle of attack is minimum at the radially place, inside edge of blade.Thereby the orientation of blade is towards outermost edges, and this outermost edges is arranged essentially parallel to the direction of the spin axis of blade.Yet outermost edges is not a straight line, but keeps small curvature.

Preferably, the curvature of centrifugation accelerates part is consistent basically, and blade is symmetrical in its outermost edges basically like this.The orientation of blade is an advantageous particularly towards outermost edges, because centrifugation accelerates partly adopts scoop shovel shape or oar shape, producing roughly Radial Flow from impeller, rather than tangent line flows.In this, the pressure drop that affacts on the airfoil-shaped portion of blade of the pressure drop ratio that affacts accelerating part is bigger.Thereby airfoil-shaped portion can produce little pulling force, the center that air is drawn in fan, and the accelerating part that extends promotes radially outwards motion of air.

Long path accelerating part is important advantage, because it avoids the turbulent flow of air to apply energy simultaneously to air, so that produce pressure gradient in new ways.

In addition, the angle of attack is in the center minimum, the speed minimum of this position, center blade, and the angle of attack increases towards outermost edges, this outermost edges position speed maximum.This helps promoting forming inlet flow profile uniformly on whole impeller eye.

According to preferred embodiment, the leading edge of blade is straight basically.Preferably, the leading edge of blade is the tangent direction along the hub portion of impeller basically.

More advantageously, impeller comprises 5 or 7 blades, and each blade has wing spiral core, and this part is along extending laterally in the centrifugation accelerates part.

The present invention further provides a kind of fan, this fan comprises impeller and housing, impeller is installed in the described housing and is rotated, this impeller comprises one or more blades, in described this blade or a plurality of blade at least one has wing spiral core, and this wing spiral core extends transverse in the centrifugation accelerates part.

In the preferred embodiment of fan of the present invention, impeller is installed in the spirality channel that is formed in the housing.

Be understandable that the angle of attack is meant the angle between blade and the blade movement direction.For special blade-section, the angle of attack of blade can obtain by center line and the angle of measuring at blade between the moving direction at blade inlet edge place.For fan of the present invention, moving direction is generally the Vertical direction of spin axis.

Description of drawings

Below in conjunction with the preferred embodiment of accompanying drawing detailed description, in the accompanying drawings according to impeller of the present invention and fan:

Fig. 1 is the side view of conventional centrifugal cutter, shows the entrance velocity figure;

Fig. 2 be the fan shown in Fig. 1 planimetric map, show that air flows out mode;

Fig. 3 is the stereogram according to the embodiment of impeller of the present invention;

Fig. 4 is the plan view of impeller shown in Figure 3;

Fig. 5 is the side view of fan shown in Figure 3;

Fig. 6 is the side view according to general fan of the present invention;

Fig. 7 is the planimetric map of the fan among Fig. 6.

Embodiment

Can be seen that by Fig. 1 and Fig. 2 the centrifugal cutter 10 of illustrated routine comprises impeller 2, impeller 2 has diameter D1 and is contained in the housing 4.Impeller 2 is driven by motor 6.The inlet diameter D2 of impeller 2 is littler than the diameter D1 of impeller 2.Typical diameter value is D1=300mm and D2=240mm.For such diameter, maximum air containment is 400 liters/second, is equivalent to the average entrance velocity of 8.8m/s.As shown in Figure 1, the zone of the impeller eye side of housing 4 comprises center low speed and low turbulent area 8, its by high-speed region 12 around.For the size and the entrance velocity of above-mentioned specification, the speed of low velocity zone 8 is 6.5m/s, and the speed of high velocity 12 is 11m/s.

As shown in Figure 2, impeller 2 is driven by motor 6, and this motor is positioned on the spin axis of impeller 2.Curved inner wall 14 is positioned at housing 4 and limits a spirality channel 16, and impeller 2 is arranged in this spirality channel 16 and is rotated.Curved inner wall 14 forms in an one tail end and closes throat sheet (close throat plate).

The schematically illustrated air of arrow A 1 and A2 is discharged mode.Shown in arrow A 1 and A2, because whirlpool, air discharge mode is curved, and wherein said whirlpool is applied on the fluid stream by impeller blade.Exhausting air has high inertia, is the 15-20m/s magnitude for the fan of above-mentioned size.

A kind of selectable design such as Fig. 3 with fan of high Elongation (aspect ratio) and combined flow pattern arrive shown in Figure 7.

As shown in Figure 3, impeller 20 comprises a plurality of

blades

22,24,26,28,30,32,34, is provided with around hub portion 36 equal angular intervals.Wheel hub 36 has crooked circumferential surface 35, and it ends at peripheral edge 37.The sense of rotation of impeller is as shown in arrow 38.Each

blade

22,24,26,28,30,32,34 comprises leading edge 40, and this leading edge 40 is along airfoil-shaped portion 39 and laterally air accelerating part 42 extensions.

Outermost edges 41 is substantially perpendicular to leading edge 40 and trailing edge 40 '.

Can see that by figure blade twists, make the outermost of each blade partly trend towards direction towards the spin axis that is arranged essentially parallel to impeller.The curvature angle of blade also along the length of blade direction along with the increase of the distance of spin axis and reduce.Thereby the inside part definition airfoil-shaped portion 39 of leading edge, air accelerating part 42 radially extends from this airfoil-shaped portion simultaneously.

Shown in Fig. 4 is impeller 20 from the observed Fig. 3 in top.Can see that from figure the degree of depth of each blade is near hub positions place maximum in a circumferential direction, and reduces towards outermost edges 41.This that is to say, looks down from above, and the thickness of blade is along with the increase of the distance of wheel hub 36 and reduce.This reducing gradually of blade is because blade twist makes with respect to the blade of periphery, make blade have bigger surface area in the position towards impeller hub and offer air-flow, and the blade at peripheral position place is to tilting away from airflow direction.

Can see by Fig. 4 that equally the leading edge 40 of each blade forms a straight line, tangentially extends from wheel hub.And the trailing edge 40 ' in accelerating part aligns with the direction of spin axis 45.

See Fig. 5 again, impeller blade extends radially outward from curved outer 35.Because the curve shape of hub surface 35, the degree of depth of blade is in the most inboard some place of blade minimum in the axial direction, and along with the distance of distance spin axis increases and increases.From this aspect, each blade all is the curvature of following wheel hub.

Yet, being different from conventional fan, blade is outside by the outermost edges of hub portion.The axial depth of blade between the outer rim and blade outermost edges 41 of wheel hub, is constant basically just at accelerating part 42 places, though the axial depth of each blade is towards preferably slight the reducing gradually of spin axis direction.

The combination of wing inner vanes part and the accelerating part that extends radially outwardly from this part can reach the effects that make air change 90 degree by fan the time.

At Fig. 6, impeller 20 has diameter D3, and is positioned at the housing 44 with choma 47.Impeller 20 is driven by motor 46.The inlet diameter D4 of impeller 20 is littler than the diameter D3 of impeller 20.Typical D3 value is 300mm, and the D4 value is 280mm.For these diameters, maximum inlet volume is 400 liters/second, is equivalent to 6.49m/s.Entrance velocity equates on the whole zone of D4 of the inlet side that passes through impeller basically.

As the example that provides among the figure, the height H 1 of impeller is near 50mm, and the height H 2 of fan includes choma, and near 80mm, and the whole height H 3 of the chamber at fan place or ventilation duct is near 150mm.And fan can effectively move when having only 70mm in the gap, so that the air velocity near 500l/s to be provided.This is inequality with conventional fan, and it is the chamber of 250mm highly that conventional fan needs, so that obtain close flow velocity.

By the wing-shaped element 40 of

impeller blade

22,24,26,28,30,32 and 34, air is pulled into the center of impeller.This has prevented to produce flow profile as shown in Figure 1, and makes air keep being drawn into equably in whole inlet diameter D2 scope.Yet be understandable that, can change the accurate curvature of blade and the air flows shape that can realize optimum performance of how much patterns to obtain to want of airfoil-shaped portion.

Straight line L1 and L2 are parallel to the spin axis of impeller.Angle between blade 24 and straight line L1 and the L2 is respectively illustrated α and β.

Angle α represents the leading edge of airfoil-shaped portion 39 and the angle between the spin axis, and angle β represents the leading edge of accelerating part and the angle between the spin axis.Angle α can 45 the degree and 90 the degree between, and angle β can 0 the degree and 30 the degree between.

The angle of attack is defined as the acute angle between blade and its moving direction.Straight line L1 and L2 are perpendicular to the sense of rotation of blade.Thereby the angle of attack of blade at the airfoil-shaped portion place can be defined as 90 °-α, and the angle of attack of blade at the accelerating part place may be defined as 90 °-β.Therefore blade can be spent between 45 degree for 0 at the angle of attack at airfoil-shaped portion place, and the angle of attack of blade at the accelerating part place can be 60 and spend between 90 degree.

Thereby the angle of attack along with along leading edge from the variation of the distance of wheel hub and change.Because blade shroud twists around leading edge, the angle of attack changes along the consistent length ground of blade.Thereby the angle of attack is in the most inboard some place of blade minimum, and at the outermost edges place 41 place's maximums.The value of the angle of attack changes to 90 degree from 0 degree on the length direction of blade.

In addition, can see that blade twist changes along its length direction.The curvature of blade is maximum near the leading edge in airfoil-shaped portion, and reduces towards the trailing edge direction.Yet the vane curvature in accelerating part is consistent between leading edge and trailing edge basically.In outermost edges, blade is basically about point-symmetric in the blade, though can see that by Fig. 4 blade is slightly prone.On the contrary, blade airfoil partly is highly asymmetric.

Can be seen that by Fig. 7 impeller 20 is driven by motor 46, this motor is positioned at spin axis 45 places of impeller 20.Motor is an outer rotor-type, and is arranged in the hub portion, so that a kind of compact design is provided.Crooked inwall 48 is positioned at housing 44, and limits a spirality channel 50, and impeller 20 is installed in this spirality channel and is rotated.Can see that (throat) 49 of throat compares by indentation with the throat sheet 18 among Fig. 1, so just can limit the passage of an opening so that air leaves housing 44.

Arrow B 1 and B2 have schematically shown the discharging modes of air.Can see that from arrow B 1 and B2 the air discharging modes are rectilinear.The air of discharging has low inertia, and maximum value is the 11m/s magnitude concerning the fan of above-mentioned size.

The running principle of the fan of Fig. 3 in Fig. 7 is as described below.The inlet characteristic of traditional centrifugal cutter makes the outer ledge place produce fast state, and produces high turbulent flow at center position, as shown in Figure 1.The design of the impeller 20 of Fig. 3 in Fig. 5 has a wing spiral core and extends transversely into the centrifugation accelerates part, makes that air velocity is uniformly on whole entrance region, provides the air of low inertia to enter.Like this,, can provide bigger inlet/impeller diameter ratio, and therefore can reduce entrance loss and noise basically, and realize than common more approaching inlet gap with respect to the impeller of the routine among Fig. 1 and Fig. 2.

Because the design of impeller, with respect to the spirality channel of the fan of routine, the design of spirality channel of the present invention also can be changed, so that realize the lower air velocity of discharge with respect to conventional fan.The long path accelerator of impeller utilization imposes on air with kinetic energy, and this increases lateral flow and eliminates the demand of closing throat sheet in the discharge section setting simultaneously.Content noted earlier can obtain than common desired narrow a lot of fan, with realize the air flows, static pressure and the noise level that obtain narrow many fans.Especially, according to the present invention, the low speed that leaves the air of blade with the whirlpool that reduces makes the degree of depth of fan reduce, to mate or to surpass the flow velocity of conventional fan, because the more uniform airflow that can obtain to enter fan and discharge fan on wideer air passageways.Although reduced the degree of depth of air passageways, also can realize above effect.

As previously discussed, Fig. 3 has an airfoil-shaped portion air is taken to the core of impeller to the fan shown in Fig. 7, produces an axial component effectively.Because fan has flowing of combination, long path accelerator has been quickened flowing of air.

The motor of fan is four-pole motor preferably, and operation frequency is 50 hertz, and the rotating speed of fan is near 1500 rev/mins like this.Also can drive the more impeller of minor diameter with bipolar motor.

According to being also advantageous in that of fan of the present invention, conventional fan need be provided with " straightener " or baffle plate to prevent to form inner vortex in outlet conduit, the perhaps discharge loss (dump loss) in other devices, and fan of the present invention does not need straightener or baffle plate.

Conventional relatively fan must be provided with odd number of blades according to fan of the present invention, for example 5 or 7.The even number blade will cause noise problem, because can produce blade path frequency (passagefrequencies).

Claims

1. the impeller of a draught fan, this impeller comprises wheel hub and one or more blade, wherein at least one blade has:

The inner radial spiral part, the cross section of this part is wing; With

The centrifugation accelerates part, this centrifugation accelerates part extends radially outward from airfoil-shaped portion,

The angle that wherein is formed between the spin axis of the leading edge of airfoil-shaped portion and impeller is bigger than the angle between leading edge that is formed on accelerating part and the described spin axis.

2. impeller as claimed in claim 1, wherein the leading edge of blade is straight along the length of blade direction basically.

3. impeller as claimed in claim 1, wherein the leading edge of blade is extended along tangent line from wheel hub basically.

4. impeller as claimed in claim 2, wherein the leading edge of blade is extended along tangent line from wheel hub basically.

5. impeller according to any one of claims 1 to 4, wherein wheel hub has crooked outer surface, and blade extends from this outer surface.

6. impeller as claimed in claim 5, wherein the accelerating part of blade extends the peripheral edge of wheel hub.

7. impeller according to any one of claims 1 to 4, wherein blade reverses around its leading edge.

8. impeller according to any one of claims 1 to 4, wherein the angle of attack at airfoil-shaped portion place is spent between 45 degree 0.

9. impeller according to any one of claims 1 to 4, wherein the angle of attack of accelerating part is spent between 90 degree 60.

10. impeller according to any one of claims 1 to 4, wherein impeller has a diameter, and this diameter is at least four times of impeller height.

11. a fan comprises as each described impeller and housing in the claim 1 to 4, described impeller is installed in the described housing with rotation.

12. fan as claimed in claim 11, wherein impeller is mounted in the spirality channel that is formed in the housing.

13. fan as claimed in claim 11, wherein said housing have open outlet throat sheet.