JPH06299997A - Mixed flow fan - Google Patents

Abstract

PURPOSE:To eliminate the unstable performance in the working condition, and reduce the aerodynamic noise by setting the sectional size on the negative pressure surface side of the leading edge part of a stator blade to be larger than the thickness of the stator blade. CONSTITUTION:A plurality of stator blades 1 are provided in the circumferential direction at equal interval between the inner wall of a casing 2 and an inner cylinder 6 on the downstream side of an impeller 8. A leading edge part 3 has the thickness 9 of the approximately arc-shaped section which is larger than the thickness of the stator blade 1. When the fluid flows in the stator blades, this constitution provides the flow along the thickness 9 irrespective of the in-flow direction, the separation at the leading edge 3 is prevented, reduction of the air-blowing efficiency caused by the separation is prevented, and the generation of the noise can be reduced. The deflection angle of the stator blades can be changed less by the thick part even when the inlet angle and the direction of the leading edge of the stator blades are different due to the change of the direction of the suction flow according to the working condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stationary blade in a mixed flow fan used in exhaust air 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 FIGS. 7 and 8. The configuration will be described below with reference to the drawings.

As shown in the figure, a plurality of vane blades 101 are arranged at equal intervals between the inner wall of the casing 102 and the inner cylinder 106. At the design point, the inlet angle of the leading edge portion 103 is in the same direction as the direction of the air coming out of the moving blade, and the outlet angle of the trailing edge portion has a shape that eliminates the swirling component and is blown in parallel with the annular ventilation port 107. ing.

In the above structure, the impeller 10 of the mixed flow fan
The general ventilation direction when 8 rotates is as shown in the figure via the mixed flow fan.

[0006]

In such a conventional mixed flow fan, if the inlet angle of the blade and the direction of the flow flowing into the stationary blade 101 are the same, the stationary blade 101 is smooth.
Although the inflow state along the line is maintained, the air flow rate changes depending on the use state, and the rotation speed of the impeller 108 also changes, so that the inflow direction does not match the inlet angle of the stationary vane blade 101, and the blade leading edge portion 103 However, there is a problem in that peeling occurs, which leads to a decrease in blowing efficiency and an increase in noise.

The present invention is intended to solve the above-mentioned problems, and is to eliminate performance instability due to use conditions, to exhibit aerodynamically good performance, and to suppress aerodynamic noise as well.

[0008]

A first means for achieving the object of the present invention is an impeller having a plurality of blades provided in a casing, and a substantially frustoconical inner cylinder provided in the casing. A plurality of stationary vane blades that are located between the inner wall of the casing and the inner cylinder on the downstream side of the impeller and support the inner cylinder, and have a cross-sectional shape on the suction surface side of the front edge portion of the stationary vane blade. Has a substantially arc-shaped thick wall.

The second means is constructed such that a thick wall having a substantially arcuate cross-sectional shape is provided at the front edge of the vane blade.

The third means has a structure in which a ring having a substantially arcuate cross-sectional shape is provided in place of the thickness of the first means.

[0011]

According to the present invention, by the structure of the above-mentioned first means, the suction flow direction depending on the use condition is changed by making the cross-sectional shape of the front edge portion of the vane blade larger than the thickness of the vane blade. Even if the inlet angle and the direction of the leading edge of the vane blade are changed, the wall thickness reduces the change in the turning angle of the vane blade, thus preventing separation and smoothing the fluid flow. It is a thing.

Further, according to the structure of the second means, by making the cross-sectional shape of the leading edge portion of the vane blade larger than the thickness of the vane blade, the direction of the suction flow changes depending on the use condition,
Even if the inlet angle of the front edge of the vane blade is different from the direction of separation, separation can be prevented, and even if the fluid flows from the suction surface side at a point close to the open state, the fluid flow can be made smooth by the thick wall. It is a thing.

Further, according to the structure of the third means, the manufacturing is facilitated by forming the cross-sectional shape of the leading edge portion of the vane blade on the substantially arc by using the ring of the same plate instead of the thick wall.

[0014]

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

As shown in the figure, a plurality of stationary vane blades 1 are provided at equal intervals in the circumferential direction between the inner wall of the casing 2 and the inner cylinder 6 downstream of the impeller 8, and the stationary vane blade 1 is The edge portion 3 has a configuration in which a resin thick wall 9 having a substantially arcuate cross-sectional shape that is larger than the thickness of the vane blade is provided.

With the above structure, when the fluid is introduced into the vane blade 1, the flow is along the thick wall 9 regardless of the inflow direction, so that the separation at the front edge portion 3 is prevented and the ventilation efficiency due to the separation is improved. It is possible to prevent the decrease and reduce the generation of noise.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. 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, in addition to the thick wall 9 of the first embodiment, a resin thick wall 10 having a substantially arc-shaped cross section is provided on the positive pressure surface side.

With the above structure, when the fluid flows into the vane blade 1, the flow follows the thick wall 10 regardless of the inflow direction, and even when the fluid is close to the open state, it flows into the thick wall 10 on the pressure surface side. Along the flow, the separation at the front edge portion 3 is prevented, and the reduction of the ventilation efficiency and the generation of noise due to the separation are reduced.

In this embodiment, the thick wall 9 and the thick wall 1 are provided.
Although 0 is made of resin, it may be integrally formed with the blade, and a porous material or a steel plate may be attached as the material.

Next, a third embodiment of the present invention will be described with reference to FIGS. 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, in place of the thick wall 9 and the thick wall 10 having the substantially arc-shaped cross section of the structure of the first embodiment, a ring 11 having the substantially arc cross section is provided at the same position. Has become.

With the above-mentioned structure, when the fluid flows into the vane blade 1, the ring 1 can be flowed in any direction.
The flow is in line with No. 1 and prevents peeling at the front edge portion 3, so that the reduction in blowing efficiency and the generation of noise due to peeling are reduced.

Since the ring 11 is made of the same material as the vane blade 1, it can be easily machined. In this example,
It is possible to prevent peeling even if the shapes of the thick wall 9, the thick wall 10, and the ring 11 are changed from a substantially arc shape to a polygonal cross-sectional shape, or if there is an uneven surface.

[0025]

As described above, according to the present invention, when the fluid flows into the vane blade by providing the thick wall and the ring at the leading edge portion of the vane blade according to the present invention. In any case, the flow will be along the thick wall and along the ring, preventing separation at the front edge, and reducing the ventilation efficiency and noise due to separation.

[Brief description of drawings]

FIG. 1 is a side view of an essential part showing the structure of a stationary blade for a mixed flow fan according to a first embodiment of the present invention.

[Fig. 2] Detailed view of the same thickness

FIG. 3 is a side view of an essential part showing the structure of a vane for a mixed flow fan according to the second embodiment.

[Fig. 4] Detailed view of the same thickness

FIG. 5 is a side view of a main portion showing the structure of a vane for a mixed flow fan according to the third embodiment.

FIG. 6 is a detailed view of the ring.

FIG. 7 is a front view showing the configuration of a conventional mixed flow fan.

FIG. 8 is a detailed view of the front edge portion.

[Explanation of symbols]

 1 Stator vane blade 2 Casing 3 Leading edge 4 Negative pressure surface 5 Positive pressure surface 6 Inner cylinder 7 Ventilation port 8 Impeller 9 Thick wall 10 Thick wall 11 Ring

Claims (3)

[Claims] 1. An impeller having a plurality of blades in a casing, a substantially frustoconical inner cylinder provided on the downstream side of the impeller, and a plurality of inner cylinders supporting the inner cylinder on an inner wall of the casing. A mixed flow fan having a vane blade and having a thick wall with a substantially arc-shaped cross section on the suction surface side of the front edge of the vane blade. 2. The mixed flow fan according to claim 1, wherein the leading edge portion of the stationary blade has a thick wall with a substantially arcuate cross-sectional shape. 3. The mixed flow fan according to claim 1, wherein a ring having a substantially arc-shaped cross-sectional shape is provided at the same position, instead of the thick wall having the substantially arc-shaped cross-sectional shape.