JPH03233196A - Multiblade fan - Google Patents

Abstract

PURPOSE:To reduce only noise value without any decrease in air quantity by applying dimensional magnitude of an outer diameter of an outside edge of a forward blade interposed between an upper plate and a lower plate so as to prevent air separation from being generated at one time. CONSTITUTION:A lower plate 2 has the same diameter as that of an upper plate 1, and is provided in the central portion thereof with a fixed boss portion 4 for installation to a rotary shaft of a motor. A curved blade 3 is caulked to the upper and lower plates 1, 2. The blade 3 is formed into a substantially rectangle, and the outside edge thereof is formed unevenly with application of dimensional magnitude of an outer diameter. A separation phenomenon of air generated in the outside edge of the blade at the time of rotation is generated not at one time over the whole length of the blade but with a time lag. Therefore, only noise value can be reduced without any decrease in air quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in multi-blade blowers (sirocco fans) used in range hoods and the like.

(Prior Art) In a multi-blade blower used in a blower unit of a range hood, the outer edges of the blades are in a straight line, and the width of the blades is the same from the upper end to the lower end.

(Problem to be Solved by the Invention) When a multi-blade blower having the above-described structure is rotated, the air separation phenomenon at the outer edge of the blade occurs at once over the entire length of the blade, which increases the noise level. have a problem

The present invention has been made in view of the problems of the prior art described above, and its purpose is to provide a multi-blade blower that can reduce only the noise level without reducing the air volume. It is in.

(Means for Solving the Problems) In order to achieve the above object, the multi-blade blower according to the present invention is characterized in that the outer edges of the blades attached between the upper and lower plates are given a size of outer diameter.

The size of the outer diameter dimension given to the outer edge of the blade may be formed by forming a plurality or one chevron shape, by sloping it linearly from the upper end to the lower end or vice versa, or by forming the above-mentioned chevron shape. For example, it may be formed with a curved line.

Further, the large number of blades installed between the upper and lower plates may have the same shape. The position of the chevron-shaped protrusions on the blade may be slightly staggered in the length direction of the blade, so that the chevron-shaped protrusion becomes a spiral, or the chevron-shaped protrusion formed on the blade may be The recesses may be arranged alternately in the circumferential direction.

(Function) According to the above means, since the outer edge of the blade attached between the upper and lower plates is uneven depending on the size of the outer diameter, the separation of air that occurs on the outer edge of the blade during rotation occurs over the entire length of the blade. Occurs with a time lag.

(Effects of the Invention) As detailed above, in the multi-blade blower of the present invention, since the outer edges of the blades are given irregularities by varying the outer diameter, air separation occurs on the outer edges of the blades during rotation. The phenomenon does not occur over the entire length of the blade at once, but occurs with a time lag. Therefore, the noise level can be lowered compared to conventional products.

Furthermore, if the unevenness is provided in the same area as the conventional blade, it is possible to reduce only the noise value without reducing the air volume.

(Embodiment) Hereinafter, embodiments of the present invention will be described based on the drawings. In the figure, 1 is a ring-shaped upper plate, and 2 is a ring-shaped upper plate, which has the same diameter as the upper plate 1 and has a central part for attaching to the rotating shaft of the motor. The lower plate 3 to which the boss portion 4 is fixed is a curved blade, and the blade 3 is fixed to the upper plate 1 and the lower plate by caulking.

The blade 3 is formed into a substantially rectangular shape, and its outer edge is formed into an uneven shape with a different outer diameter.

The uneven shape of the outer edge is not limited to a straight line with a plurality of chevron-shaped protrusions 3a provided within the length (height) range of the blade as shown in FIG. The blade is sloped linearly from the upper end to the lower end, and the blade is sloped so that the width becomes narrower from the central part in the longitudinal direction toward the upper and lower ends as shown in Fig. 4. ), or one in which a plurality of mountain-shaped protrusions 3a are formed by a curved line as shown in FIG.

In addition, for the large number of blades to be installed between the upper and lower plates, one type of blade is selected from among the blades mentioned above, and the installation is not limited to the form, but the position of the convex portion formed on the blade 3. The blades are formed by being slightly shifted in the length direction of the blade, and they are arranged sequentially between the upper and lower plates so that the position of the convex portions forms a spiral as a whole, or the convex portions and concave portions of the blade are alternately formed. It is also good to combine the two types of blades as appropriate, such as alternately arranging them in the circumferential direction.

Next, experimental results of the multi-blade blower according to the present invention and a conventional product will be explained.

<Product of the present invention> Outer diameter: 180 mm Shape of the outer edge of the blade; as shown in Figure 1 <Conventional product> The outer diameter, length and number of blades are the same as the product of the present invention, and the outer edge of the blade is straight (same width). Measurement conditions> Measure the noise value (dB) and rotation speed at the same air volume (530 m3/h) <Measurement results> Noise value (dB) Rotation speed (rpm) Invention product
45 778 Conventional product 46 8
06

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a longitudinal sectional front view, FIG. 2 is a partially cutaway plan view, and FIGS. 3 to 5 are front views showing other examples of the blade shape. In the diagram, 1: Upper plate 2: Lower plate 3: Blade

Claims (1)

[Claims] In a multi-blade blower in which a large number of forward-facing blades are provided between an upper plate and a lower plate, the outside edges of the blades are given a size of outer diameter to prevent air separation from occurring all at once. Features a multi-blade blower.