Centrifugal multi-blade blower

Abstract

A centrifugal multi-blade blower includes an impeller, and a casing that accommodates the impeller, and draws in air at least from an inlet port of the casing which opens on one end side of a rotation shaft and blows out the air radially outward of the rotation shaft. The impeller includes a main plate that is joined to the rotation shaft, vanes which are arranged around the axis of the rotation shaft and the other end sides of which in the rotation axis direction are connected to the main plate, and a side plate that connects together the vanes on their one end sides in the rotation axis direction. The vanes are characterized in that an inlet angle on a cross-sectional surface crossing each inner peripheral edge part of the vanes on a meridian plane of the impeller in a predetermined direction is evenly made in the entire region from the side plate-side through the main plate-side, and that outer peripheral edge parts of the vanes are configured to be away from the axis of the rotation shaft from the main plate-side toward the side plate-side.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application is based on Japanese Patent Application No. 2012-142803 filed on Jun. 26, 2012 and Japanese Patent Application No. 2013-100170 filed on May 10, 2013, the disclosures of which are incorporated herein by reference.TECHNICAL FIELD[0002]The present disclosure relates to a centrifugal multi-blade blower that draws air from a direction of a rotation axis and blows out the air radially outward of the rotation axis.BACKGROUND ART[0003]An impeller of a conventional centrifugal multi-blade blower includes vanes arranged around the rotation axis, and blows out radially outward the air, which is drawn from the direction of the rotation axis.[0004]In this impeller, a wind direction rapidly changes from the rotation axis direction to the radial direction at spaces between adjacent vanes (hereinafter referred to as an inter-vane space) near an air inlet. Accordingly, the air does not flow easily compared to on an opposite side from the i...

AI Technical Summary

Benefits of technology

[0019]The present disclosure addresses the above issues. Thus, it is an objective of the present disclosure to provide a centrifugal multi-blade blower that can sufficiently evenly make a flow speed distribution in a rotation axis direction on an air outlet side of an impeller.

[0020]To achieve the above-described objective, the present inventors have earnestly given a great deal of consideration. As a result, with their attention turned to the fact that in a centrifugal multi-blade blower, a flow rate of an impeller on its air outlet side increases in proportion to the second power of an outer peripheral diameter of the impeller under conditions where rotating speed and draft resistance are constant, they have worked out a centrifugal multi-blade blower that can evenly make a flow speed distribution on the air outlet side of the impeller.

[0022]As described above, in such a configuration that the inlet angle is evenly made in the entire region from the side plate side through the main plate side, the outer peripheral diameter of the impeller is larger on the side plate side than on the main plate side. Accordingly, a flow rate on the air outlet side on the side plate side of the impeller can be increased. As a consequence, a flow speed on the air outlet side on the side plate side of the impeller can be increased compared to the impeller of the conventional technology.

[0023]Moreover, in accordance with the increase of the flow rate on the air outlet side on the side plate side of the impeller, a flow rate of air flowing into the inner peripheral edge part on the side plate side increases. This increase of the flow rate of air flowing into the inner peripheral edge part on the side plate side makes faster a flow speed (absolute inflow speed) on the side plate side. Accordingly, an inflow angle on the side plate side can be brought close to the inlet angle.

[0024]As a result, the exfoliation of the air flow on the side plate side can be restricted as compared with the impeller of the conventional technology, and there can be mitigated a reduction of the flow speed on the air outlet side on the side plate side in association with the exfoliation of the air flow on the side plate side.

[0025]For the above reason, the centrifugal multi-blade blower of the present disclosure can sufficiently evenly make a flow speed distribution in the rotation axis direction on an air outlet side of the impeller, which becomes an issue in the impeller of the conventional technology.

Problems solved by technology

In a case of a large difference (incidence angle) between an inlet angle (inlet condition) of an inner peripheral edge of the vane and an inflow angle (inflow condition) of the air flowing into the vane, there is a tendency that the air flow exfoliates in the inter-vane space, and the impeller of the centrifugal multi-blade blower loses speed.

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