JPH06299998A - Mixed flow fan - Google Patents

Abstract

PURPOSE:To provide a mixed flow fan capable of reducing the noise level in the working condition by specifying the shapes of rotor blades, a hub and stator blades. CONSTITUTION:A plurality rotor blades 1 are provided on the outer circumference of a hub 2, and the shape of the rotor blade is such that D2i/D2o may be in the range of 0.85-0.9 where D2i is the outer diameter of the inlet of the rotor blade 1, and D2o is the outer diameter of the outlet, D1i/D1o may be in the range of 0.45-0.55 where D1i is the inner diameter of the inlet, and D1o is the inner diameter of the outlet, L/D1o may be in the range of 0.28-0.3 where L is the width of the rotor blade in the direction of the rotation axis, and the mean fitting angle of the inner circumferential edge of the rotor blade relative to the rotation axis may be in the range of 52 deg.-55 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixed flow fan used in exhaust blowers and air conditioners.

[0002]

2. Description of the Related Art Recently, exhaust blowers and air conditioners used in residential and non-residential spaces have been required to reduce noise generated during operation.

Conventionally, a mixed flow fan of this type is generally shown in FIG. The configuration will be described below with reference to the drawings.

As shown in the figure, a plurality of moving blades 101
Is attached to a substantially frustoconical hub 102, and is arranged in an annular casing 112 along the outer peripheral edge 103 while maintaining a constant clearance in the circumferential direction. The moving blade blade 101 has a shape in which the center of the chord is advanced in the rotation direction from the root portion 104 of the moving blade blade 101 toward the outer peripheral edge 103. Further, the casing 112 and the casing 1 are provided downstream of the moving blade 101.
The vane blades 108 are arranged between the inner cylinders 113 in 12 so as to support the inner cylinder 113.

In the above structure, the general ventilation direction when the mixed flow fan rotates is that the mixed flow fan allows the mixed flow of air.

[0006]

In such a conventional mixed-flow fan, when the air flow on the blade surface goes from the leading edge to the trailing edge, the fluid does not flow completely in accordance with the theory, so The flow may not follow the blade 101. In addition, there is a problem that delamination is likely to occur on the negative pressure surface of the blade due to deceleration near the surface due to the viscosity of the fluid, and there is a problem that rotational noise is generated due to the rotation of the moving blade 101. Further, the turbulence when the fluid collides with the hub 102 is one of the causes for increasing the noise.

The present invention solves the above problems, and a first object thereof is to reduce noise generated during operation.

The second object is to increase the air volume and improve the efficiency.

[0009]

In order to achieve the above first object, the mixed flow fan of the present invention has a first means comprising a plurality of moving blades on the outer periphery of a hub. In the shape, when the inlet outer diameter is D2i and the outlet outer diameter is D2o,
When D2i / D2o is in the range of 0.85 to 0.9 and the inlet inner diameter is D1i and the outlet inner diameter D1o, D1i / D
When 1o is in the range of 0.45 to 0.55 and the width in the direction of the rotation center axis of the moving blade is L, L / D
2o is in the range of 0.28 to 0.3, and the average of the mounting angles of the inner peripheral edge of the moving blade and the rotation center axis is 52 ° to
The configuration is in the range of 55 °.

In order to achieve the first object and the second object, the second means is such that, in the shape of the moving blade, the difference in mounting angle between the inner peripheral edge and the outer peripheral edge is in the range of 3 ° to 10 °. And θt is the pitch angle between the blades at the point where the outer diameter is the maximum when the blades are viewed from the direction of the rotation center axis, and the maximum both ends of the outer peripheral edge are formed in the cross section in the radial direction with the rotation center axis. When the angle is θs, θs / θt is 0.94.

Further, in order to achieve the first object, the third means is that when the hub inlet diameter is D3i and the hub outlet diameter is D3o, D3i / D3o is in the range of 0.4 to 0.43. , Has a streamlined shape.

In order to achieve the first object, a fourth means is located downstream of the moving blades, between the casing and a substantially frustoconical inner cylinder in the casing, and the inner cylinder is provided. Assuming that the inlet area is Si and the outlet area is So in the radial cross section of the vane blade that supports, So / Si is 1.2.
When the velocity of the inlet portion of the vane blade is Vi and the velocity of the outlet portion of the vane blade is Vo,
The fluid velocity ratio Vo / Vi from the inlet of the vane blade to the outlet of the vane is 0.9 or less.

[0013]

According to the present invention, with the structure of the first means described above, the fluid flowing on the blade surface can be smoothly guided without being rapidly accelerated, and therefore the separation on the blade surface can be reduced.

Further, with the construction of the second means, by assuming a forced vortex flow on the blade surface, the amount of work at the outer peripheral portion of the blade is increased, the air volume is increased, and the fluid flowing on the blade surface is made smooth. The noise can not be increased by flushing.

Further, the structure of the third means can reduce the turbulence of air impinging on the hub.

Further, with the construction of the fourth means, the fluid flowing from the rotor blade can be stabilized in a state parallel to the axis without being disturbed, and the swirling component can be eliminated to reduce the conduit resistance.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG.

As shown in the figure, a plurality of blades 1 are provided on the outer circumference of the hub 2, the average mounting angle is θ, and the outlet outer diameter is D2.
o, the inlet outer diameter is D2i, the outlet inner diameter is D1o, the inlet inner diameter is D1i, and the axial width of the moving blade 1 is L, θ is in the range of 52 ° to 55 °, and D2i / D2o is 0. .8
5 to 0.9, and D1i / D1o is 0.45
It is in the range of 0.55 and L / D2o is 0.28 to 0.3.
It is composed of a range of.

With the above structure, when the rotor blade 1 is rotated, the flow on the blade surface can be smoothly flowed without rapidly increasing the speed, and noise can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in the figure, in the structure of the first embodiment, the difference between the average values of the mounting angles at the inner peripheral edge 4 and the outer peripheral edge 3 is 3 ° to 10 °.
Where θt is the pitch angle between the blades and θs is an angle formed by both end points of the outer peripheral edge, θs / θt is 0.94.

With the above structure, the amount of work increases in the portion near the outer peripheral edge 3 during the rotating operation of the moving blade 1, so that the amount of air increases, and the warping of the moving blade 1 is reduced. The fluid can flow smoothly. Further, since the fluid in the outer peripheral portion 3 of the positive pressure surface 11 is surely worked, the fluid is not caught in the negative pressure surface 10 in the middle of the moving blade 1.

Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in the figure, if the inlet diameter of the hub 2 is D3i and the outlet diameter of the hub 2 is D3o in the configurations of the first and second embodiments, D3i / D3o is 0.4 to 0.43.
It is composed of the form.

With the above-mentioned structure, the fluid impinging on the hub 2 can smoothly flow when the moving blade 1 rotates.
Also, the fluid flowing on the surface of the hub 2 is unlikely to separate.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in the drawing, the vane blades 8 installed between the casing 12 and the inner cylinder 13 in the casing 12 in the configurations of the first, second, and third embodiments.
Of the cross section in the radial direction of S0 is So and the entrance area is Si
Where So / Si is in the range of 1.2 to 1.4, and the velocity of the inlet portion is Vi and the velocity of the outlet portion is Vo, the fluid velocity ratio Vo / Vi from the inlet portion to the outlet portion is Is 0.9 or less.

With the above structure, the fluid flowing from the rotor blade 1 is stabilized in a state parallel to the rotation center axis 9 without being disturbed, and a swirling component is generated when the fluid is discharged to the outlet of the stationary blade 8. It can be eliminated to reduce the line resistance.

[0029]

As described above, according to the present invention, according to the present invention, the fluid flowing on the surface of the moving blade and the surface of the hub and at the outlet of the stationary blade is smoothed without being rapidly accelerated. It is possible to provide a mixed flow fan that can reduce the noise and increase the noise.

Further, it is possible to provide a mixed flow fan which increases the work amount of the outer peripheral portion of the moving blade and increases the air flow rate.

[Brief description of drawings]

FIG. 1 is a side sectional view of a mixed flow fan according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of the mixed flow fan of the second embodiment.

FIG. 3 is a front view of the same.

FIG. 4 is a side sectional view of the mixed flow fan of the third embodiment.

FIG. 5 is a side sectional view of the mixed flow fan of the fourth embodiment.

FIG. 6 is a side sectional view of a conventional mixed flow fan.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Moving blade blade 2 Hub 3 Outer peripheral edge 4 Inner peripheral edge 8 Stationary blade 9 Rotation center axis 12 Casing 13 Inner cylinder

Claims (4)

[Claims] 1. A plurality of blades are provided on the outer periphery of the hub,
When the inlet outer diameter is D2i and the outlet outer diameter is D2o in the shape of the rotor blade, D2i / D2o is 0.85 to
Within the range of 0.9, the inlet inner diameter is D1i and the outlet inner diameter is D
When 1o, D1i / D1o is 0.45 to 0.55
L / D1o is in the range of 0.28 to 0.3, and the inner peripheral edge of the rotor blade is A mixed flow fan, wherein an average of mounting angles formed with the rotation center axis is in a range of 52 ° to 55 °. 2. The shape of the moving blade is such that the difference in mounting angle between the inner peripheral edge and the outer peripheral edge is in the range of 3 ° to 10 °, and the outer diameter of the moving blade is maximum when viewed from the direction of the rotation center axis. Where θt is the pitch angle between the rotor blades at the point where θs is the maximum angle, and θs is the angle between the maximum both ends of the outer peripheral edge in the radial cross section with the rotation center axis. The mixed flow fan according to claim 1, wherein the mixed flow fan is 94. 3. The hub has an inlet diameter of D3i and an outlet diameter of D3o.
In this case, D3i / D3o is in the range of 0.4 to 0.43 and has a streamlined shape, and the mixed flow fan according to claim 1 or claim 2. 4. Downstream of the rotor blade, between the casing and a generally frustoconical inner cylinder within the casing,
When the inlet area in the radial cross section of the stationary blade supporting the inner cylinder is Si and the outlet area is So, So / Si is in the range of 1.2 to 1.4, and When the velocity of the inlet portion is Vi and the velocity of the outlet portion of the vane blade is Vo, the fluid velocity ratio Vo / Vi from the inlet portion of the vane blade to the outlet portion of the vane blade is 0.9 or less. The mixed flow fan according to claim 1, 2 or 3, wherein: