DE23234C - Shovel on fans - Google Patents

Description

IMPERIAL

PATENT OFFICE

The present invention relates to a new blade shape for fans. The ones constructed so far Fans suffer from two ailments, on the one hand they have a great one Speed, on the other hand, they create a lot of friction and ^

What the first evil
you can do it with every little one
prove without effort by the revision
often 5,000 to 10,000 in the rik

wearing. But also larger fans
With the usual ratio of the outer wheel diameter to the tube diameter, require too high a number of revolutions as soon as the tension becomes unusually high.
. _: Touching the latter inconvenience, we shall easily comprehend it, considering how sharp bends and distractions through the air often must, and how strong Stöfsen it faces. For all rationally constructed fans with a guide housing, i.e. with a cover that encloses the impeller on the outer circumference for the purpose of collecting the escaping air and delivering it to the pressure pipe, it must be emphasized that the air never emerges tangentially from the wheel into the guide housing , but in a direction that differs significantly from the tangent to the wheel. This results in substantial material losses, because the air cannot remain in the direction given by the impeller, as the guide housing forms a solid wall against which the air impacts, with only the side component of the original speed along the guide housing towards the pressure pipe reach. Of the

the paddle wheel is a valve, while it is much smaller in the case of oren, in the

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50IdäfäC ^ r ^ Buit very close tangential from the Furthermore, the usual itift forums always have a transition neck on ^ LeTtlager, because the speed at which the air exiting the paddle wheel is much larger (2 to 5 times) than that in the pressure pipe. This transition neck is much too short for there to be no loss of effect caused by changes in speed. Have fans without a guide housing usually the disadvantage that the air escapes from the wheel at too great a speed, so that losses of effect arise. All these air deflections and loss of strength due to contraction because of rapid changes in cross-section and speed have a disadvantage Influences on the efficiency, so that at the same time in consideration of the high number of revolutions the permissible compressive stress for the centrifugal fans is only very low.

Existing fans, on the other hand, should be arranged with the help of the blade shape in such a way that First, the number of revolutions remains small by choosing a suitably large diameter and, secondly, the air is expediently guided and all unnecessary cross-sectional and changes in speed, as well as all violent material losses, are avoided.

The new blade shape forms a variable Archimedean spiral, namely one in whose polar equation r = a - φ der

Factor α either decreases uniformly when the polar angle φ increases, where r is the radius vector. The law for the decrease or increase of the factors depends on the given circumstances.

The number of blades depends on the size of the blades and their light weight Manufacture determined. You can either uninterrupted all of the entry scope of the wheel extend to the extent of the exit or they can be partially shortened so that there are either more blades at the inlet than at the outlet, or vice versa.

The procedure for tracing the blade shape is as follows:

First of all there is always a diagram for the speeds and an auxiliary construction required, after which the blade can be recorded.

Let the following quantities be given (see Fig. I), provided that the Air entering the paddle wheel at the inner circumference:

i \ the inner wheel radius,

r _{2 is} the outer wheel radius,

gi is the absolute speed when entering the paddle wheel,

g _{2 the} same exit speed,

V _{1 is} the inner peripheral speed of the wheel,

V _{2 is} the outer peripheral speed of the same,

ei is the radial component of g ₁ (this speed can be changed by a bit to allow for a reverse motion, similar to that of a ship's propeller),

e _{2 is} the radial component of ^ ₂ ,

U _{1 is} the relative speed with which the air moves along the blade when entering the wheel,

U ₂ this relative speed at the exit,

Iz _{1 is} the blade height at the inlet volume,

b _{2 the} same for the scope of exit.

In order to first record the diagram of the speeds, one plots the circumferential speeds of the wheel V ₁ = AB and V ₂ = AG in any scale on the straight line AG in Fig. 2, divide the distance BG into several equal parts, build in the partial points BCDE ... Lothe upwards and downwards, set off the radial entry velocity e _t - BB ^{1 in} the plumb line in B and also in the plumb line in G a length J = GG ¹ upwards. This length y is taken in such a way that C _{1 is} in the same proportion to y as the volume of air at the entrance to that at the exit. Connect now in Fig. 2 G ¹ with B ¹ by a straight line, which the Lot in C ¹ D ¹ E ¹ . . . intersects, connect these points C ¹ D ¹ E ¹ . . .

with A through straight rays that intersect the solder BB ¹ at the points marked in the figure, and draw parallels from these points to AG to the corresponding solder, that is, to C "D" E " ... Below the line AG one carries in the perpendiculars the associated blade heights BB ₁ = Ii ₁ , CC ₁ DD ₁ ... GG ₁ = b _t ab, connect the points B ₁ C, D ₁ ... with a curved line, draw a parallel through B ₁ AG which D _{11. n is} the perpendiculars in C ₁₁ e.. G cuts _11, propose to the points CDE ... as centers of arcs with CC "DD" EE ". . . as a radius downwards, connect the intersection points of these circles in AG with C ₁ D ₁ E ₁ . . . by straight lines, draw parallels to them through C ₁₁ D ₁ , E ₁₁ . . . to AG and mark off their intersection points around the points CDE ... as center points after the upper perpendiculars. In the sections ■ CC "DD ¹ " EE '" ... one now has a measure for the relevant radial components of the absolute velocities of the air.

For exact calculations, instead of the actual blade heights, something smaller must be used Insert diagram, whereby the blade thicknesses are taken into account.

If, for the sake of clarity, the line AG with the plumbs BB ¹ CC "D D '" EE "' ... from the first diagram is transferred to another point, FIG. 3, a parallel B ¹ A ¹ is drawn through B ¹ AG, then assume a direction BH for the absolute entry speed g _x in B (it can be either to the right of BB ^x or in the same or to the left of this line), connecting H with A, then one has the inner circumferential speed in AB V ₁ , in BH the absolute entry speed gi and in AH the blade speed U ₁ , ie the speed at which the air etc. moves along the blade (see FIG. 1).

Assume, furthermore, a line GJ in G so that J lies in a parallel through G '" with AG , further that GJ is equal to the absolute exit velocity g ₂ , or that the exit angle <C JG A has the desired size, namely for the fans with a guide housing up to 2 °, 3 ⁰ or 5 °, while for those without a guide housing the angle can be larger (50 ⁰ to 90 ⁰ ).

Then, in a similar way as before, one has the outer circumferential speed V ₂ in AG , the absolute exit speed g ₂ in GJ and the blade speed u ₂ in AJ . At all these speeds, their directions can be seen in the diagram.

The rays AH and AJ are now extended to H ¹ and J ¹ and the points JI ¹ ImUJ ¹ are connected either by a straight line or according to fixed points of view

by any arbitrarily curved line with one another.

For the sake of simplicity and for the sake of introduction, a straight line is assumed in the figure, while curved lines will be discussed below. One connects the intersection points of the straight line HJ ¹ in the upwards

extended plumb bobs BB ¹ CC "DD '" with

A through straight rays, draws through C "D '" E "' ... parallels with AG after these rays and finally lays a curve Η · ede f J. through the points found. Then all velocities are determined by the figure an arbitrary radius r _x , which may correspond to point D , one has in the straight line Dd drawn in thought the absolute speed ^ _{x of} the air, in AD the circumferential speed v _% and in A d the blade _{speed «x} .

If you transfer the peripheral speeds from this diagram to a coordinate system (or radius) as abscissa and the absolute velocities as well as the Blade velocities as ordinates above, one obtains two curves which represent the Specify the growth and decrease of these two speeds precisely.

But if one wants to prescribe a different law for their growth and decrease for these speeds, one must either transform the connecting line If ¹ - / ¹ into a single or multiple curved line or the blade heights BB ₁ CC ₁ DD ₁ . . . change, while GG _{1 of} course remains unchanged.

This is the graph of the speeds.

In order to carry out the auxiliary construction, in Fig. 4, on the straight line AG, take the angles ■ < HA G and <^ JAG from the previous Fig. 3, make AB = F ₁ and AG = Vi, establish Lothe BH in B and G and GJ, which intersect the legs AH and AJ of the plotted angles in H and J , and lay such a line through these points that the present area A GJH becomes geometrically similar to the area A GJ ¹ H ¹ in the previous Fig. 3. Then the surface in Fig. 4 has the peculiarity that the Loth BH has a value U _{1 of} the factor α in the polar equation r = α φ of the blade shape for the radius vector T ₁ , and the Loth GJ has a different value _{3 of the} same factor the radius vector r ₂ , therefore the intermediate Lothe in CDE ... represent different values of α for the intermediate radii vectors.

Now, in Fig. 5 , plot any length on the straight line MN , divide this into any number of equal parts, establish Lothe in the partial points (not indicated in the figure for the sake of clarity), and part in the previous Fig. 4 (there also not indicated for the sake of clarity) the length BG in as many equal parts and erect in the same Lothe up to the line HJ. Then one has the property of the Archimedean spiral according to these plumb bobs, or in other words, to the different values Ci ₁ . ; . a _{2 of} the factor α as a radius the associated circumference 2 U ₁ π. . . 2 a ₂ π , to divide it by a number η (ζ. Β. 8) and then to subtract the quotients found in the plumbs of the new Fig. 5 upwards and finally the upper points by a suitable line M ¹ -N connect to. If one extends the plumb bob in N so far upwards that the length NO is equal to the outer wheel radius r ₂ and OP equal to the inner radius V _{1 on} any scale, then P connects M ¹ with a straight line and draws a parallel through M to NE, which intersects the curve M ¹ N ' in a , a Loth falls from α to MN to a _t , draws a parallel through ^ ₁ to M ¹ P to NE to b ₂ , which intersects M ¹ N ¹ in b, b falls from a perpendicular to ^ ₁ uild process is continued until we get beyond the line NO, the figure is finished. (If one thinks it is more correct, one can lay the line PM ¹ through P and M instead of M ¹ and proceed as before.) The reason for this process can easily be seen when one considers that the angles which the blade speeds correspond to the peripheral speeds in the diagram, or, what is the same, the angles which the vane walls enclose for a given radius with the tangents to their circles are determined by the diagram, and therefore the vane shape must be such that this condition is in fact fulfilled. If one looks at the shape of the shovel, which is to be discussed immediately, one soon finds that it is at Y ₈ revolution ^! / ₈ of 2 α _χ π more must be set to the previous one in order to get the radius vector.

One has z. B. at the commencement of the radius vector r _x and for '/ ₈ - rotation y ₈ from the circular circumference of the value α in the polar equation r = α φ as a radius, MM ie ¹ = Pa ₂ to add more; so that the radius vector = r _s - \ - Pa ₂ = Oa ₂ becomes etc.

This is the auxiliary construction.

Now you can draw the shovel shape yourself:

One suggests in Fig. 6 with r _x and r. _t circles, divides the circumference of the same into Ji ₁ (here eight) equal parts, connects the subpoints in circumference with the center Q by straight lines, inserts the circle in O of the auxiliary construction, detects Oa ₂ , carries this length in the new one Figure from Q to Q ₁ to β , grab Oh ₂ in the circle, carry it to Q ₂ to γ

Claims (1)

and continues like this until you get to the outer circumference. By the points found α. β δ γ. . . . you can finally put the shovel shape you are looking for. The above procedure can be shortened as follows: In the diagram of the speeds in FIG. 3, set on the line AG (not indicated in the figure) from A to G to the radius r ₃ , where A is the starting point At the end point a plumb line upwards, extend all rays A HA c etc. after this plumb bob, determine for the greatest length (x) in the plumb line, i.e. up to the point of intersection with the extended ray AH as a radius the length of a corresponding circle circumference, divide the same through η (here eight) and now put a lot y on the line AG so that the line through the line AH im Loth cut length the size - · 2 χ π ft receives. On a line (similar to NO in Fig. 5) place the radii r _x and r ₂ , divide the distance between r _x and r _% into as many equal parts as in BG in Fig. 3, erect Lothe and insert the length y with all intersection points of the rays from FIG. 3 in the plumb line belonging to t- _s , connect this with the starting point of the straight line (O in FIG. 5 correspondingly) and put a through the intersection points of these rays with the plumb lines curved line (similar to M ¹ -JV ¹ in Fig. 5), put an angled triangle of 45 ⁰ at the end point of 7-j, draw a line up to the curved line, make a plumb line, draw a line under the angle again of 45 ° and drop a plumb bob until you get to the end point of r ₃ . The intersections found in the straight line are exactly the same as a ₂ h C ₂ . . . in Fig. 5. The practical implementation of these fans is illustrated in FIGS. 7 to 13, and although FIGS. 7 to 10 each show a horizontal fan in the elevation and in the outline, while FIGS. 12 and 13 each have a standing position Represent fan. Figs. 8, 10 and 11 show examples of the blade shape for different cases. The impellers of the fans can either have divergent side surfaces, such that the blade height in Figs. 7 and 9 increases from α β on the inner circumference to γ & on the outer circumference, or they can have parallel side surfaces, Figs. 12 and 13, or convergent side surfaces as with ordinary fans. The air would not exit tangentially enough because the speed of the air at The exit from the wheel was assumed to be the same as that in the pressure pipe, so assume the exit speed of the air is greater than the speed of the air in the pressure pipe, but must mediate a gradual transition between these speeds. This does the inventor by using a diffuser called) of great length, but it is easier to manufacture because of bends and: around the actual casing of the fan. in one or more Winds around it. Such a diffuser is shown in FIG. 10, where it extends from the housing at e, through fg and h , to the pressure pipe at i , while the actual housing is indicated by abcd and e . This diffuser enables the air etc / even with parallel and even convergent Side surfaces almost tangentially exiting from the wheel and the conditions set above to be met. The fans shown in Figs. 7 to 13 all have an open inlet, so that the air or type of gas is sucked in directly from the surrounding space. However, the fans can also be used with a closed inlet (exhaustors), i. H. with special tubes are provided, which the air or gas type out. a distant Move space after the fan so that the fan has a suction effect. Finally can the fan can be made sucking and pressing. Patent claim: The arrangement of the blade in the form of a variable Archimedean spiral according to the information contained in the description is constructed. For this purpose 2 sheets of drawings.