JPH0454078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a Sirotskov fan used in small air conditioners and the like.

Conventional technology The configuration of the conventional general Sirotskov fan is
This will be explained using FIG. Blades 7a arranged parallel to the rotation axis between the boss portion 9 and the retaining ring 8
An impeller 7 having a shape is housed in a fan casing 2 equipped with a bell mouth 3, and is driven by a motor 4 to generate a flow as indicated by an arrow A.

As shown by arrow A, the suction flow enters along the rotation axis of the impeller, passes through the bell mouth, and then changes its direction by 90° in the radial direction.
However, it is difficult to rapidly change the direction of a flow that has momentum in the axial direction, and the retaining ring side, where the change is abrupt, cannot be turned sufficiently, and the flow is directed from the retaining ring side to the hub side.
A detachment C from the bell mouth and retaining ring is formed. Therefore, the actual flow path at the impeller outlet is narrower than the height of the blades. This separation phenomenon occurs due to the transition of axial flow to radial flow, and is a different phenomenon depending on whether the flow follows the blade in a plane perpendicular to the rotation axis, and the optimum entrance angle of the blade. This is something that cannot be solved by .

Problems to be Solved by the Invention As mentioned above, since there is a dead water area with extremely low flow rate on the retaining ring side of the impeller, the flow path height at the impeller outlet is not the path height D, but is actually E. There is a flow only in that part. For this reason, compared to when the flow exists over the entire height of the blades, the effective height of the blades becomes smaller, resulting in lower air blowing performance, and when obtaining the same flow rate, the discharge flow speed becomes faster, which increases noise. There was a problem.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention holds one end of a plurality of blades arranged in an annular manner with a retaining ring, provides a boss portion at the other end, and rotates the blades around the rotation axis. The plurality of blades are arranged so as to be inclined from the boss side toward the retaining ring side in a direction opposite to the blade rotation direction.

Effect By adopting the above configuration, the fluid passing through the blades is given not only a force in a plane perpendicular to the rotation axis, but also a force in the direction of the rotation axis. That is, as shown in FIG. 3, if the angle that the circumferential cross section of the blade makes with the rotational axis direction is ξ, then the force F that the blade applies to the fluid has an axial component of magnitude F·sinξ. Therefore, when passing through the blades, the flow is given a velocity component in the axial direction from the boss side to the retaining ring side, so the flow moves as a whole from the boss side to the retaining ring side, and the dead water area on the retaining ring side is small. Become. In addition, if the flow passing through the impeller moves from the boss side to the retaining ring side and flows almost uniformly over the entire height of the blades, the amount of work that the blades do to the fluid will also become almost uniform, which will improve the discharge flow. There will be less turbulence.

In this way, by increasing the effective height of the blades and giving a uniform amount of work to the flow,
Improve the ventilation performance of the impeller.

Examples Examples of the present invention will be described below with reference to FIGS. 1 and 2. The blades 1a arranged between the boss portion 6 and the retaining ring 5 have a shape that is smoothly inclined from the boss side toward the retaining ring side. FIG. 3 is a partial cross-sectional view of the blade 1a of this impeller taken along a cylindrical surface centered on the rotation axis. In the figure, the fluid flows from the back of the paper toward the front. In such flow conditions, the in-plane force exerted on the flow by the inclined vane 1a rotating in the direction of the arrow is F perpendicular to the vane 1a. This force F is divided into a circumferential component Fcos and an axial component Fsin, and the axial component Fsin causes the entire flow to receive a force directed from the boss side to the retaining ring side. Therefore, the entire flow passing through the impeller spreads toward the retaining ring,
The dead area that conventionally existed on the retaining ring side becomes smaller. Therefore, the flow passes through a wider range of blade heights, which spreads the effective blade area, improves air blowing efficiency, and lowers the discharge flow rate at the same flow rate, leading to a reduction in noise. . Furthermore, in response to a substantially uniform inflow due to a smaller dead area, the amount of work that the blades give to the flow becomes substantially uniform in the blade height direction. Therefore, turbulence in the discharge flow is reduced, and efficiency and noise reduction are achieved.

Further, the inclined shape of the blade is not limited to the shape shown in FIG. 2, but the same effect can be obtained by using a blade shape such as the other embodiment of the present invention shown in FIG. It is determined in relation to the casing shape.

Effects of the Invention As described above, the Shirotsuko fan of the present invention has the blade shape tilted from the boss side toward the retaining ring side and in the opposite direction to the rotation direction, thereby expanding the flow area toward the retaining ring side. Since the dead area is reduced and the effective height of the blades is increased, the air blowing efficiency is increased and the discharge flow velocity is reduced, resulting in a low noise effect. Furthermore, if the inflowing flow becomes uniform, the amount of work that the blades apply to the flow becomes almost uniform, which has the effect of suppressing disturbances in the discharge flow.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional side view of the casing of a Sirotskov fan showing an embodiment of the present invention, Fig. 2 is a perspective view of the Sirotskov fan, and Fig. 3 is a cross-sectional view of the Sirotskov fan cut along a cylindrical surface centered on the rotation axis. FIG. 4 is a perspective view of a conventional Sirotskov fan showing another embodiment of the present invention, FIG. 5 is a side view of a conventional Sirotskov fan with the casing taken in section, and FIG. 6 is a perspective view of the same Sirotskov fan. 1... impeller, 1a... vane, 3... bell mouth, 5... retaining ring, 6... boss section.

Claims (1)

[Claims] 1 One end of a plurality of annularly arranged blades is held by a retaining ring, a boss is provided at the other end, and the plurality of blades are arranged around the rotation axis from the boss side to the retaining ring side. Shirotskov fan tilted in the opposite direction to the direction of blade rotation.