JPH02223697A - Multivane fan - Google Patents

Abstract

PURPOSE:To reduce the generation of noise by a method wherein an oblong hole positioned in a range of 0-60 deg. from the tip of a tongue part in a reverse direction to the rotation direction of an impeller and having inner and outer size being in a specified ratio to the outer size of the impeller and a specified length in a peripheral direction is formed in the delivery port part of a casing. CONSTITUTION:An oblong hole 5 positioned in a range of 0-60 deg. from a tongue part 6 in a reverse direction of the rotation direction of an impeller 101 and having inner and outer sizes D1 and D2 being 110-120% and 120-140%, respectively, of an outer size D0 of the impeller 101 and length (l) in a peripheral direction being 40-50% of the diameter of the impeller is formed in the delivery port 4 part of a suction casing 1. In this constitution, where the impeller 101 is rotated, air is sucked through a suction port 104, and the pressure of air in the casing is increased to a value higher than that of the suction part of the impeller 101. However, since the oblong hole 5 is opened in the suction casing 1, air is returned through the oblong hole 5 to a suction part on the outer side according to an internal pressure, a reverse flow through the impeller 101 and a gap is reduced, and the generation of noise can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a multi-blade fan used in air conditioning equipment and ventilation equipment.

2. Description of the Related Art Conventionally, as shown in FIG. 6, a multi-blade fan of this type has an impeller 101, a volute casing 102 surrounding the impeller 101, and a suction casing 10 having a suction port 104.
The configuration included a casing 106 (6).

Problems to be Solved by the Invention In the conventional multi-blade fan described above, as shown in FIG. A pressure difference is generated between the inside B of the impeller 101, and when the forward flow a passing through the impeller 101 collides with the reverse flow that tries to return to the suction side due to the pressure difference, a crackling noise is generated.

The present invention has been made in consideration of the above-mentioned conventional problems, and an object of the present invention is to provide a multi-blade fan with low noise.

Means for Solving the Problems In order to solve the problems, the present invention provides: an impeller having blades, surrounding the impeller with a casing consisting of a spiral casing and a suction casing having a suction port;
And in the configuration in which the casing has a discharge port, the discharge port portion of the suction casing has an angle of 0° to
O°, and the inner diameter and outer diameter are 110% - 120% and 120% - 140% of the outer diameter of the impeller.
%, and is configured as a multi-blade fan provided with elongated holes having circumferential lengths of 40% to 60%.

Effect: With this configuration, the air in the high-pressure portion inside the casing flows to the suction side through the long holes, and backflow from the impeller blades to the suction side is suppressed, resulting in low noise.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4. Note that the same parts as in the conventional example are given the same numbers and detailed explanations are omitted. In the figure, IQl is an impeller, which is surrounded by a casing 3 consisting of a spiral casing 102 and a suction casing 1 having a suction port 104. The casing 3 has a discharge port 4, and the suction casing 1 has a discharge port 4 that is 0° to 60° in the direction opposite to the rotational direction of the impeller 1010 from the tongue tip 6 of the spiral casing 102.
', and the inner diameter D1 and outer diameter D2 are the impeller 1.
110% to 120 inches and 120 to the outer diameter D0 of 01
% to 140%, and the circumferential length l is 4o% to tso%
A long hole 6 is provided.

In the above configuration, when the impeller 101 rotates, air is sucked into the suction port 104, and the pressure is increased by the impeller 101.
It passes through the inside of the casing 3 and is discharged from the discharge port 4. The pressure of the air inside the casing 3 is higher than that of the suction portion C' of the impeller 10f due to the pressure increasing action of the impeller 101, and the gap between the outer periphery of the impeller 101 and the suction port 1o4 and the impeller 101. From 104A, it attempts to return to the suction section C'. However, since the elongated hole 5 is opened in the suction casing 1, air returns to the suction part C outside the suction casing 1 according to the pressure inside the casing 3, and from the impeller 1o1 and the gap 104A. This reduces backflow and reduces noise generation.

Furthermore, since the air that has returned to the suction portion C from the upper elongated hole 5 is sucked in again through the suction port 104, the air volume does not decrease or stagnate. Incidentally, FIG. 4 shows changes in air volume and noise when the size and position of the elongated hole 6 are changed. As a result, the optimum value for the long hole 6 was determined. That is, the inner diameter of the long hole is 1.1 to 1.2 with respect to the impeller outer diameter D0, and the outer diameter D2 is 1.2.
˜1.4, and if the length l is in the range of 0.4 to 0.5, it is clear that noise can be lowered than in the conventional case without long holes.

Effects of the Invention As is clear from the description of the embodiments above, according to the present invention, the pressure difference between the suction part inside the casing, which is the inside of the impeller, and the inside of the casing, which is the outer peripheral part of the impeller, can be reduced by By providing a long hole in the discharge port of the suction casing, the airflow is made even. This eliminates the backflow of airflow into the impeller and prevents backflow due to turbulence of the airflow, without reducing the amount of air blown. It has a simple structure and aims to reduce noise.

[Brief explanation of the drawing]

Fig. 1 is a side view of a multi-blade 7-ang according to an embodiment of the present invention;
The figure is a perspective view of the multi-blade fan, Fig. 3 is a cross-sectional view of the multi-blade fan, Fig. 4 is a relationship between the long hole shape and performance of the multi-blade fan, and Fig. 5 is a conventional multi-blade fan. FIG. 6, which is an fP+ view of the fan, is a sectional view of the multi-blade fan. 1... Suction casing, 3... Casing, 4... Discharge port, 6... Elongated hole, 6
...Tongue, 101... Impeller, 102
...Volume casing, 104...Suction port. Name of agent: Patent attorney Shigetaka Awano and one other person A5 Aji

Claims (1)

[Claims] An impeller having blades is surrounded by a casing consisting of a spiral casing and a suction casing having a suction port, the casing is provided with a discharge port, and the impeller is inserted into the discharge port portion of the suction casing from the tip of the tongue of the spiral casing. is located in the range of 0° to 60° in the opposite direction to the rotational direction of the impeller, and has an inner diameter and an outer diameter of 110° with respect to the outer diameter of the impeller.
% to 120% and 120% to 140%, and the length in the circumferential direction is 40% to 50%.