JPS6380098A - Multi-blade fan - Google Patents

Abstract

PURPOSE:To improve the fan efficiency, by providing an arched bellmouth having the axial length variable in the circumferential direction of an impeller within the range of 70-90% of the inner diameter of the impeller as a small suction port on a spiral casing. CONSTITUTION:A suction port 7 of a quarter arch facing with an opening of a sideboard 3 of an impeller 5 is formed through a spiral casing 6. A small suction port 8 having an endface 9 of a quarter arch is fixed to the inside of the suction port 7 such that a gap (g) is provided between the endface 9 of the suction port and the inner diameter of the impeller 5. Since air flow can flow uniformly to the impeller through the inside suction port having different axial length in the circumferential direction, the fan efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a multi-blade blower used as a ventilation blower for home appliances or equipment.

2. Description of the Related Art A conventional multi-blade blower will be described with reference to FIGS. 3 to 5. In FIG. 3, 6 is a spiral casing, and an impeller 6 attached to the rotating shaft 1 is provided inside the casing. This impeller 6 is constructed by attaching a plurality of blades 4 between a main plate 2 and a side plate 3.

A flange-shaped suction lower is disposed in the spiral casing 6 so as to face the opening of the side plate 3 of the impeller 6.

Problems to be Solved by the Invention In such a configuration, as shown in FIG. 4, the airflow from the suction lower has a steeper curve as it approaches the blade 4, which causes resistance. Therefore, the speed of the airflow caused by the blades 4 becomes smaller on the side plate 3 side,
A dead space S is created through which airflow cannot pass. Further, as shown in FIG. 6, the dead space S is located at a position A in the circumferential direction of the impeller 6.

It varies depending on B, C, and D. In this case, the part with small airflow required a low amount of input, but the work was low, which caused a decrease in the efficiency of the impeller as a whole.

The present invention takes into consideration the above-mentioned conventional problems and aims to provide an efficient multi-blade blower.

Means for solving the problem In order to solve this problem, the multi-blade blower of the present invention has the following features:
It consists of a spiral casing and an impeller that is rotatably provided within the spiral casing and has an opening in the center.
The spiral casing is provided with a suction port whose opening diameter is the same as the inner diameter of the impeller, and a substantially arc-shaped bell mouth whose axial length changes in the circumferential direction of the impeller at 70 to 90% of the inner diameter of the impeller. The structure includes a small suction port.

Function: With this configuration, the air sucked through the suction port is carried toward the side plate of the blade along the suction port with a small inner diameter, so that the wind speed distribution on the blade becomes uniform.

Embodiment Hereinafter, an embodiment of the present invention will be described based on FIGS. 1 and 2. The same components as those in the prior art are given the same numbers and detailed explanations will be omitted. In the figure, 6 is a spiral casing, and 6 is an impeller attached to the rotating shaft 1. This impeller 6 has a plurality of blades 4 attached between a main plate 2 and a side plate 3, and has an opening in the side plate 3. The spiral casing 6 includes a side plate 3 of the impeller 6.
An arc-shaped suction lower is formed facing the opening of the
Furthermore, a small suction port 8 having an arc-shaped end surface 9 is installed inside the suction lower so that the end surface 9 of the suction port has a gap y with the inner diameter of the impeller 6.

The operation of the multi-blade blower constructed in this way will be explained. When the impeller 6 rotates, air is sucked in from the suction lower and the small suction port 8 of the spiral casing e, and is discharged from the discharge port 10 of the impeller 6. Only about % of the axial length of the blade flows from the main plate side of the blade. Moreover, the areas where the flow does not pass (dead spaces) change in the circumferential direction. However, if the end face of the small suction port 8 is formed into an arc shape, the inner diameter is made smaller than that of the suction lower, and the axial length L is changed in the circumferential direction according to the dead space. Flow also flows into the blade, increasing the pressure evenly across the entire blade, making it possible to do the same work efficiently as before.

Note that even if the axial length L is mounted without changing in the circumferential direction, a certain degree of effect is exerted.

Effects of the Invention As is clear from the description of the embodiments above, according to the present invention, the suction port of the spiral casing is made double on the outside and inside,
Airflow is uniformly flowed into the impeller from the inner suction port whose axial length differs in the circumferential direction to perform work, which has the effect of improving the efficiency of the blower.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a multi-blade blower according to an embodiment of the present invention, FIG. 2 is a top view of the same, FIGS. 3 and 4 are sectional views of a conventional multi-blade blower, and FIGS. b is a configuration diagram and a characteristic diagram showing changes in the circumferential direction of the flow dead space of the same multi-blade blower. 6...-- Impeller, 6... Spiral casing, 7... Suction port, 8... Small suction port. Agent's F + Ta Attorney + Middle EtfI! Kawa Oto ≠) 1ri Figure 1 Figure 2 Figure 3 Figure 5

Claims (1)

[Claims] consisting of a spiral casing and an impeller rotatably provided within the spiral casing and having an opening in the center,
The spiral casing is provided with two suction ports, one having an opening diameter that is the same as the inner diameter of the impeller, and the other having an axial length that is 70% to 90% of the inner diameter of the impeller. A multi-blade blower consisting of a small suction port with an approximately arc-shaped bell mouth that changes in the circumferential direction.