[0001] The invention relates to centrifugal blowers, also known as regenerative blowers,
used for supplying the airflow for furnaces or in other industrial applications.
[0002] Briefly, these blowers consist of a rotor caused to rotate by a motor, generally
electric, having the form of a disc on the edge of which the blades are arranged.
[0003] The latter move inside a toroidal chamber formed in the stator, which communicates
with a suction channel and a delivery channel situated on one side of the motor, parallel
to the axis of rotation.
[0004] In the operation of side channel blowers, the blading imparts pressure to the air
or other fluid processed, forcing it to circulate in a spiral path along the toroidal
chamber.
[0005] The configuration of the blading significantly affects the performance of side channel
blowers; however, there are also other factors having a decisive effect, especially
if it is wished to increase the flow rate or the pressure of the fluid processed by
the blower.
[0006] For this purpose, blowers are known which use two stages in parallel to have a higher
flow rate, or in series to achieve greater delivery pressure; however, it does not
follow that doubling the rotors also doubles the flow rate or pressure of the air,
whereas it is certain that it does increase the complexity of the machine.
[0007] For this reason, machines have been devised with only one rotor in which the blading
and the stator are designed to operate in more than one mode by changing the relative
position of the suction and delivery apertures; a similar solution described in US
patent 3,915,589 does not appear advantageous, however, since the (theoretical) benefits
achieved do not compensate for the disadvantages because when the blower operates
with stages in parallel, its flow rate is lower compared with that of a normal blower
having the same dimensions.
[0008] In other words, the theoretical increase in delivery pressure resulting from connecting
the stages in series is obtained to the detriment of the flow rate of the blower when
it operates in normal conditions with stages in parallel.
[0009] The technical problem addressed by the present invention is therefore that of overcoming
the disadvantages of currently known blowers; the concept for solving this problem
consists in producing a machine with modular stages, that is stages which may be used
singly, or connected in series or parallel.
[0010] According to a preferred form of the invention, the blower is characterised in that
the suction and discharge of the air from each stage are obtained by means of manifolds
which divide the flow of air so as to match the operation of the stages in series
or in parallel.
[0011] Other characteristics of the invention and the effects deriving therefrom will become
clear from the following description concerning a preferred and nonlimiting example
of embodiment illustrated in the appended drawings, in which:
figure 1 is a longitudinal section of a blower according to the invention;
figures 2 and 3 are a front view and section view along the diameter of the rotor,
of the blower in figure 1;
figures 4 and 5 show, respectively from the front and from the rear, half of the toroidal
chamber of the blower in figure 1;
figure 6 is a section along the line VI-VI in figure 5;
figures 7 and 8 are respectively a front view partly in section and a side view of
a blower according to the invention, with two stages in series;
figures 9 and 10 show sections of the preceding two-stage blower, viewed from the
opposite side compared with that in figure 7;
figure in 11 is a section of a blower according to the invention, with two stages
in parallel.
[0012] With reference to these drawings, in them the number 1 indicates as a whole a blower
according to the invention, having an outer casing 2 in which an electric motor 3
of known type is housed.
[0013] The latter drives a shaft 4 to which are keyed a cooling fan 5 at one end and a rotor
6 for processing the air at the opposite end.
[0014] The rotor 6 is constituted by a central disc 8 which extends from the hub 9 to a
peripheral ring 10, along which are located the blades 12; these have a convex spoon
shape and are divided in the median plane by a baffle 14 constituted by a tapering
elongation of the ring 10, which extends as far as the ends of the blades 12.
[0015] In the blower 1, the blades 12 of the rotor move in a toroidal chamber 15 formed
between a body 16 attached with screws to the casing 2 and a cover 18 attached to
the above-mentioned body; the body 16 and the cover 18 constitute respective shells
of a casing which contains the rotor: given their substantially equal form, only the
first of these will be described hereafter with reference to figures 4-6 and what
will be stated shall be understood valid also for the second.
[0016] As can be seen, the body 16 is equipped externally with radial ribs 20 and peripheral
ribs 21 , while internally it has an annular cavity 23 which forms the internal wall
of the toroidal chamber 15.
[0017] In the bottom part of the cavity 23 with reference to figures 4 and 5, there are
two ports 25, 26 communicating respectively with the manifolds 27 and 28 associated
with the suction side channel 29 and the delivery side channel 30 of the blower (in
figure 1, only channel 30 is shown).
[0018] According to a preferred embodiment, the manifolds 27 and 28 are constituted by respective
walls 37 and 38 having a substantially semicircular shape (cf. figures 4 and 5) so
that they are open at the top thereby facilitating the passage of the air towards
the ports 25 and 26.
[0019] Each of the semicircular walls 37 and 38 is surrounded by a space 39 and 40, whose
function will become clearer in what follows when dealing with the blower with two
stages in parallel; in the blower with only one stage of figure 1, the above-mentioned
spaces are instead closed by the acoustic insulation 42 present in the side channels
29, 30 for suction and delivery.
[0020] At the opposite end the side channels 29, 30 and the manifolds 27, 28 are closed
by a cover 44.
[0021] Finally, in the area 31 comprised between the ports 25 and 26, the cavity 23 has
a shape matching that of the blades 12 (cf. figure 1); this is made to form a labyrinth
seal between the two ports, enabling the air to be discharged through the above-mentioned
ports during operation of the blower which takes place as follows.
[0022] The air coming from the outside enters the blower through the side suction channel
29 (not shown but parallel to the channel 30) and continuing through the manifold
27, reaches the toroidal chamber 23; it is just the case to point out that the same
thing also happens on the other side of the toroidal chamber formed by the cover 18,
on which there are ports similar to ports 25 and 26 present on the body 16 housing
the rotor 6.
[0023] In other words, when it reaches the manifold 27, the flow of outside air running
through the suction channel divides and enters the toroidal chamber 15 from two sides,
one on the body side and the other on the cover side.
[0024] Inside the toroidal chamber, the blades 12 drive the air along opposite sides with
respect to the baffle 14: the latter therefore acts as a dividing wall which prevents
interference in the movement of the air that may cause pressure losses.
[0025] It will be observed that the baffle 14 and the blades 12 have the same radial height,
thus creating uniform conditions both with respect to the median plane and with respect
to the outer circumference of the rotor 6.
[0026] Advantageously, however, the radial height of the baffle and of the blades is smaller
compared with that of the toroidal chamber 15, so as to maintain the same pressure
on both sides of the rotor.
[0027] Air is sent to the delivery channel 30 at each revolution of the rotor, through the
port 26; the latter is arranged to the side with respect to the blades 12, while the
manifold 28 is in a tangential position relative to the path of the blades and is
configured with a semicircular cross-section.
[0028] This provides for the discharge of the air from the toroidal chamber 15, because
the side port 26 is adjacent to it and there are no obstacles to overcome or ducts
to run through while the position and semicircular shape of the manifold 28 assist
the centrifugal component of the velocity of the air, so as to make full use of the
associated energy and not lose pressure.
[0029] The same advantageous effects are also obtained, mutatis mutandis, by the air being
sucked in through the inlet port 25 and the manifold 27.
[0030] The most important point, however, is that these effects are also achieved in the
case of a blower with two stages S, S' in series or in parallel.
[0031] The first of these is shown in figures 7-10, which give various views of a blower
with two stages S, S' connected in series, the parts already seen in the previous
example being indicated by the same reference numbers, while the new ones are distinguished
by an apostrophe.
[0032] As can be seen, in this case the suction channel 29 is no longer arranged horizontally
by the side of the electric motor 3, but is vertical and positioned at the end of
the blower; the latter is equipped with an added compression stage, which comprises
a rotor 6' keyed onto the shaft 4 next to the other rotor 6 and identical thereto.
[0033] The blower 6' is housed in a body 16' closed by a cover 18', identical to those of
the adjacent rotor but rotated with respect to them by an angle α (figure 8) so as
to line up the outlet manifold 28' of the first stage with the inlet manifold 27 of
the other stage (cf. figure 10); in this way, the two stages are connected in series
with each other.
[0034] It is just the case to point out that the manifold 28' of the first stage is closed
by a plug 44' at the opposite end of the manifold relative to the one at which it
is connected to the second stage, which in turn is closed by a plug 44 at the free
end.
[0035] The operation of each stage S, S' of this blower is identical to that of the preceding
case, so that for the sake of brevity reference may be made to what has already been
said; it is in any case clear that at the delivery outlet of the blower there will
be a pressure approximately double compared with that of a single stage blower.
[0036] What should however be pointed out here is the embodiment of the blower in modular
form, obtained by using a longer shaft 4 so as to be able to fit the two identical
rotors 6, 6', and adding, compared with the previous single stage blower, the cover
18 and the body 16' identical to each other and connected in series simply by rotating
one relative to the other.
[0037] This simple and effective embodiment gives clear savings for the industrial production,
since the differences between the blowers with one or two stages are reduced substantially
to a few parts.
[0038] It should moreover be pointed out that the modular structure designed in this way
is also suitable in principle for producing blowers with three or more stages; all
that is required for this purpose is to add to the shaft 4 a rotor housed between
a body and a cover like those described, offset angularly relative to the adjacent
ones according to the description just given.
[0039] The same is true for the blower with two stages S, S' laid in parallel, shown in
figure 11, though there is no angular offset between them.
[0040] The reason is that in this case the air inlet manifolds 27, 27' are lined up (and
not offset) so as to be fed from the same flow of air sucked into the side channel
29; the same happens with the outlet manifolds 28, 28' (not shown in figure 11) through
which the air blown by the rotors 6, 6' passes.
[0041] It is clear that in this case the volume of air processed by the blower is greater
than the previous one; for this reason, the space 39, 39' which surrounds the manifolds
27, 27' is also used in order to increase the cross-section through which the air
passes.
[0042] More particularly, the channel 29 advantageously has a cross-section equal to that
of the manifold 37 with the associated space 39, to which it is joined by means of
a coupling 47 (the latter might also not be needed if the channel 29 had a diameter
such that it could be aligned with the manifold 27).
[0043] In this way the flow of air coming from the channel 29 is divided and one part goes
into the manifold 27, while the other passes into the space 39 and 39'; the first
part is then further reduced because a fraction of it is drawn off by the first stage
S of the blower, while the other goes into the manifold 27' to be drawn off by the
second stage S'.
[0044] By contrast, the flow of air which passes into the space 39 and 39' flows directly
into the manifold 27' to be drawn off by the second stage S': this allows the latter
to operate in uniform optimum conditions, since the flow which feeds it is substantially
equal to that which reaches the first stage S.
[0045] This flow is given by the sum of that which passes into the manifold 27 and which
is not drawn off by the first stage S, plus that which passes into the space 39, 39'.
[0046] Consequently, as can be seen, in this case too the modular embodiment of the blower
provides a simple two-stage machine which differs from the previous ones only by a
few parts.
[0047] Finally, it should be pointed out that although the blower according to the invention
has been described in this example for blowing air, it can in any case be used with
other gases and may also be used to generate vacuum; for this purpose, it is only
necessary to connect its inlet channel to the volume in which the vacuum is to be
produced.
1. A side channel blower, comprising:
a toroidal chamber (15) in which there are at least one inlet port (25) and one outlet
port (26) for the air or other fluid processed,
a rotor (6) with a plurality of peripheral blades (12) which extend into the toroidal
chamber (15),
a suction channel (29) and a delivery channel (30) communicating respectively with
the inlet port (25) and outlet port (26) of the toroidal chamber (15),
characterised in that each of said ports (25, 26) is associated with a respective tubular manifold (27,
28) extending transversely to the median plane of the rotor, connected to one of said
channels (29, 30) at one end and capable of being connected to another manifold (27',
28') at the other end.
2. A blower according to claim 1, wherein each manifold (27, 28) has an open cross-section
at the end having the port (25, 26) associated with it.
3. A blower according to claims 1 and 2, wherein around each manifold (27, 28; 27', 28')
there is a space (39, 40; 39', 40').
4. A blower according to the preceding claims, wherein the inlet and outlet ports (25,
26) are formed in the wall of the toroidal chamber (15) in a position beside the blades
(12) of the rotor (6).
5. A blower according to the preceding claims, comprising a body (16; 16') and a cover
(18, 18') placed side by side to form the toroidal chamber (15) between them.
6. A blower according to claim 5, wherein the manifold (27, 28; 27' 28') is constituted
by parts formed as one piece respectively in said body (16, 16') and cover (18,18').
7. A blower according to claims 5 and 6, wherein a plurality of stages (S, S') each comprising
a body (16, 16'), a cover (18, 18') and the associated rotor (6, 6'), are fitted to
the same shaft (4) and are connected in series with each other by offsetting them
angularly with respect to each other, so as to connect the respective outlet manifold
(28') and inlet manifold (27).
8. A blower according to claims 5 and 6, wherein a plurality of stages (S, S') each comprising
a body (16, 16'), a cover (18, 18') and the associated rotor (6, 6') are fitted to
the same shaft (4) with the respective inlet manifolds (27, 27') and outlet manifolds
(28, 28') connected to each other, and wherein the suction and delivery channels (29,
30) have a cross-section equal to that of said manifolds plus that of the spaces (39,
40; 39', 40') surrounding them.
9. A blower according to any one of the preceding claims, wherein between the blades
(12, 12') of at least one rotor (6, 6') there is a baffle (14, 14') having the same
radial height as the blades, which divides the surfaces of these in two and which
extends in a plane transverse to the axis of rotation of the rotor.
10. A blade according to claim 9, wherein the baffle (14, 14') is constituted by the tapering
prolongation of a ring (10,10') of the rotor (6, 6').
11. A blower according to claim 10, wherein the baffle (14, 14') lies in a median plane
of the blades (12, 12').