JPS59593A - Fan - Google Patents

Abstract

PURPOSE:To raise the static pressure efficiency of a fan, by employing such an arrangement that centripetal acceleration is caused at the front half of a blade and axial-flow or mixed-flow acceleration is caused at the rear-half of the blade so that a high static pressure can be obtained without stator blades. CONSTITUTION:Blades 3 are fixed to the outer circumferential surface of a hub 2 of an impeller 1 whose surface is shaped substantially in hyperboloid of one sheet, and the part of the leading edge 3a of the blade 3 located on the tip side 3a1 is tilted to extend in more parallel to the fluid flow than the part of the leading edge 3a located on the hub side 3a2. The outer circumferential surface of the hub 2 is composed of a front curved surface 6a where centripetal acceleration directed obliquely toward the inside is produced and a rear curved surface 6b where axial-flow acceleration in the axial direction or mixed-flow acceleration directed obliquely toward the outside is produced. Thus, since the centripetal acceleration is produced at the front half of the blade and the axial-flow acceleration or mixed-flow acceleration is produced at the rear half of the blade, a high static pressure can be obtained without stator blades. Therefore, it is enabled to increase the chord length of the blade, to make a fluid flow through fluid passages between the blades substantially at a uniform speed, to reduce the internal loss of a fan and to raise the static pressure efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blower that sucks in fluid centripetally from the outer circumference and discharges it from the center.

Figures 1 and 2 show seven examples of conventional centripetal blowers (
Special Public Show 3! ;-20071 publication) converts dynamic pressure to static pressure on the inner circumferential side of the front stator vane 3' for giving pre-swirl to the incoming air, and the trailing edge bl of the rotor blade A'. A rear stator vane ≠' is attached to each for closing.

Here, the operation of a general centripetal blower will be explained.

FIG. 3 shows the blade inlet (front line α') when the rotor blade λ' is operated in the centripetal blower shown in FIG. and exit (trailing edge 2
The velocity triangle at b′) is shown. In Fig. 3, the symbol U is the peripheral speed (-), C is the absolute speed (%), and W
ti indicates the relative velocity (%), and the subscript / in each symbol indicates the inlet, the letter the outlet, the term the circumferential component, and the letter the radial component, respectively.

Now, the theoretical total pressure increase P@ caused by the operation of rotor blade λ'
(IIIA)) is given by the following formula.

p, = γno (U, 09, -U, OS, )
...(1) Here γ; Specific weight of fluid Ckf/
d) 9: Acceleration of gravity C-/l') In the equation (1), in the case of FIG. 3, since there is no front stator vane 3', the fluid flows in the radial direction and O=10.

Therefore, P= = Vy (U, Os,)
(2) Therefore, compared to the case where a centrifugal fan with the same outer diameter as the conventional centripetal blower is operated at the same rotation speed, Ll<U, and the resulting theoretical total pressure increase The theoretical static pressure increase Pg caused by the operation of the rotor blade λ is given by the following equation.

PI, “ps 7 G”/-29 (/W)
...(') Here, Ma: Day 7 In the user efficiency formula (8), if there is no trailing stationary vane, then Ma > 0-
It is. In the case of a centrifugal fan, a vortex chamber or a vortex-shaped chamber is installed, and the static pressure recovery of the dynamic pressure γOl'/, 2y is performed well due to the same as the diffuser efficiency η, so that a high static pressure can be obtained. It has become.

Considering the above points, a centripetal blower having only rotor blades has a smaller increase in static pressure at the same rotation speed than a normal centrifugal fan.

As a countermeasure against this problem, in the past, as shown in Figs. The front stator vane 3' is installed so as to increase the theoretical total pressure rise P given by the above formula (1), and the trailing edge of the rotor blade, 2b'
By installing a rear stator vane l on the inner peripheral side, the dynamic pressure γC,n,! in the above equation (8) is calculated. 9 is used to restore static pressure as much as possible.

In the centripetal blower shown in FIGS. 1 and 2, the velocity triangle at the leading edge of the rotor blade, 21L', and the trailing edge 2b' of the rotor blade when the rotor blade λ' is operated is shown in FIG. There is.

Therefore, the static pressure increase PJ obtained by this centripetal blower is given by the following equation.

P, r = rig (U, Csz, u+cvb,
)-γ'12.9 (/-t))-△P,
...(4) Here, △PI: Fan internal loss This fan internal loss ΔP8 is the loss in the front silent blade.

It is expressed as the sum of losses in the rotor blade, loss in the rear stator blade, right angle bending loss at the outlet, and other losses.In the conventional centripetal blower, (α) Since it has a stationary vane J, there is potential interference with the dynamic R,2' and loss due to the surface friction loss of the stationary vane itself.(A) Motion with a relatively short chord length L' (C) By installing a trailing stationary vane≠', the rotation speed component Os
.

Exit absolute velocity with 0. Direct it in the radial direction to C・-
Even if 〇m, the inner diameter r of the trailing stationary blade is the inner diameter r of the moving noodles.
Since it becomes smaller than ζ, a, -C, becomes smaller, and recovery of static pressure from dynamic pressure is hardly expected. Losses due to the presence of sharp right-angled bends towards (-) rotor blade λ' and stationary blade 3', ! Possible causes include noise increase due to potential interference due to the combination of I', etc. Therefore 1. In the above equation (4), the fan internal loss ΔF,r becomes large, and the resulting rise in static pressure becomes small.

As mentioned above, conventional centripetal blowers have the problems of low static pressure efficiency and large noise. Furthermore, there is a problem in that the structure becomes complicated due to the necessity of front stator vanes and rear M stator vanes.

In view of the above-mentioned problems, the present invention has been devised so that the outer peripheral surface shape of the substantially monoplane hyperboloid hub constituting the impeller can produce inward centripetal acceleration and axial flow acceleration or outward diagonal flow acceleration. The static pressure efficiency of the blower is improved by constructing it with a new curved surface and creating a shape that does not produce centripetal acceleration in the front half of the blade, but allows axial flow or diagonal flow acceleration to occur in the rear half. In order to achieve this purpose, an impeller having a substantially monoplane hyperboloid hub, a plurality of blades planted on the hub, and a guide guide covering the outer periphery of the impeller are provided. A front curved surface that causes the tip side of the leading edge of each blade to be inclined closer to the flow direction than the hub side, and that causes the outer peripheral surface of the hub to be centripetally accelerated diagonally inward. and a rear curved surface that produces axial flow acceleration in the axial direction or diagonal flow acceleration diagonally outward, and centripetal acceleration in the front half of the blade, and axial flow or diagonal flow acceleration in the rear half. It is characterized by having a shape that can cause

Hereinafter, a blower according to an embodiment of the present invention will be explained with reference to FIGS.

FIG. 5 shows a first embodiment of the present invention, and this blower has a substantially monoplane hyperboloid hub 2 and a plurality of blades 3, 3, etc. implanted on the outer peripheral surface of the hub 2. It is constituted by a wheel, a guiding rod enclosing the outer periphery of the impeller, and inlet guide plates 3.6 that are perpendicular to the axial direction and parallel to each other in the suction region of the impeller.

The shape of the outer peripheral surface of the hub λ is a concave shape such that the radius of the intermediate portion is smaller and the radius of the trailing edge is larger than the leading edge radius T. That is, the diameter of the front curved surface ttL from the leading edge to the middle portion is gradually reduced, while the diameter of the rear curved surface tb from the middle portion to the rear edge is gradually expanded, so that "m>TI>
rH. A main plate part 7 to which a drive shaft is to be connected is provided approximately at the center of the inner surface of the hepu, and can be integrally molded with synthetic resin.

The front edge 3α of each blade 3 is inclined so that the tip side 3a, which is the outer diameter side, is closer to the hub side 3α, which is the inner diameter side, and has a large approximately conical annular area. is formed. Reference numeral 3b indicates the trailing edge of the blade.

Furthermore, the tip side end surface 3c of each blade 3 is formed into a concave shape that is approximately the same shape as the outer peripheral surface of the hub λ.

The guide hole has an inner radius r that is the rear edge portion 3b of the blade.
The radius r on the tip side of the impeller is formed to be larger than that, making assembly of the impeller easier.

When the impeller/ having the above configuration is driven, the inflow guide plates j, j
The air flow W sucked in from the radial direction through the passage between each vane 3. The first half of the air flow receives smooth centripetal acceleration diagonally inward, and the second half of the air flow W receives smooth centripetal acceleration diagonally outward at right angles to the edge 3a, thereby further increasing the curvature of the streamline of the air flow W. ing.

FIG. 3 shows a third embodiment of the present invention, in which the intermediate portion radius r and the trailing edge radius r are made equal to each other on the outer circumferential surface of the hub λ in the first embodiment. The rear curved surface 6b is made into a cylindrical surface so as to produce trickle acceleration in the axial direction at the rear half of the blade.

Next, the effects of the blower of the present invention will be listed below.

(1) The tip side 3a of the leading edge 3a of the blade 3 implanted on the outer peripheral surface of the substantially monoplane hyperboloid hub λ, and the hub side 3a
, while tilting it closer to the flow direction,
The outer circumferential surface of the hubco is composed of a front curved portion Oa that causes centripetal acceleration diagonally inward and a rear curved surface 6b that causes trickle acceleration in the axial direction or diagonal flow acceleration diagonally outward,
Since the front half of the blade can generate centripetal acceleration and the rear half of the blade can generate axial flow acceleration or diagonal flow acceleration, high static pressure can be obtained even without stationary blades, and the chord length can also be increased. By increasing the flow rate and making the flow velocity in the blade passage approximately constant, a smooth blade surface load distribution and a streamline pattern with a large curvature can be obtained, which makes it possible to reduce the internal loss of the fan, making it even more efficient. A blower with high performance and high static pressure efficiency can be obtained.

(2) As a result of improving the performance and static pressure efficiency of the blower, the same capacity can be produced at a lower rotation speed, and noise is reduced because there is no sound generated due to potential interference due to the presence of conventional stator blades. can be measured.

(8) Since it is not necessary to install stationary blades as in the conventional example, the counting can be significantly simplified.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a conventional centripetal blower, and Figure 2 is a vertical cross-sectional view of a conventional centripetal blower.
Figure ■-■ Half-section cross-sectional view 3 Velocity triangle at the blade inlet and outlet of a centripetal blower in the case of no expanding stationary blades, Figure ≠ is the speed triangle at the blade population and outlet of the centripetal blower in Figure 1, 5 is a vertical cross-sectional view of the blower according to the first embodiment of the present invention, FIG. 6 is a velocity triangle of the blade inlet and outlet of the blower of FIG. 5, and FIG. 7 is a performance (solid line) of the blower of FIG. Figures Drough, G, and D, which compare the dimensionless flow coefficient φ and static pressure coefficient ψI, with those of the conventional example (shown with dotted lines) are related to the first and third embodiments of the present invention, respectively. FIG. 3 is a longitudinal cross-sectional view of the blower. / ... Impeller λ ・I+L1+Hub 3 ...Blade 3a ...Blade leading edge part ... :・Guide 6a ...Front curved surface 6b ・・・・Rear curved surface

Claims (1)

[Claims] 1. An impeller (1) having a substantially monoplane hyperboloid-shaped heb (C) and a plurality of blades (3), (J), etc. planted on its outer peripheral surface; and the impeller (1) In the blower, the tip side (3α1) of the front edge portion (3a) of each blade (3) is
is inclined closer to the flow direction than the heb side (34), and the outer peripheral surface of the hub (2) is formed with a front curved surface (6α) that causes diagonally inward centripetal acceleration and an axial direction. It consists of a rear curved surface (≦b) that causes axial flow acceleration to the blade or diagonal flow acceleration diagonally outward.