JP2024126871A - Centrifugal fans and air conditioners - Google Patents

Abstract

To provide a centrifugal fan for rendering vortex generated by air involved in the rear side of a bell mouth harmless to secure the smooth flow of air while increasing an air flow on the rotary-shaft-direction end side of an air fan.SOLUTION: A casing 110 includes a spiral part of which the inner peripheral face opposed to the outer periphery of an impeller has a greater distance from a rotary shaft as extending from a winding start P to a winding end. The spiral part includes an outer periphery plate part 130 covering an area on the outer periphery side of the impeller, and a side plate part 120 having a suction port 121 in the center. The suction port includes a bell mouth 122 having an inner diameter reduced as extending to the axial inside. An annular protruded part 140 is provided extending from the side plate part in the rotary shaft direction while being spaced from the bell mouth toward the radial outside. The annular protruded part which is concentric with the bell mouth, and lower than the bell mouth, forms a space S from the bell mouth, into which air flows.SELECTED DRAWING: Figure 9

Description

The present invention relates to a centrifugal blower and an air conditioner equipped with the same.

A circular intake port is provided in the center of the casing of a centrifugal blower such as a sirocco fan, and the intake port is provided with a bell mouth whose inner diameter decreases toward the inside in the direction of the rotation axis (see, for example, Patent Document 1). The air sucked into the intake port increases in speed as it passes through the bell mouth.

JP 2016-61278 A

When air sucked in through the bell mouth is exhausted in a centrifugal direction by the impeller, the air gets caught behind the bell mouth (the inner surface of the casing at the end of the fan in the direction of the rotary shaft) and forms a vortex, which causes a problem of narrowing the effective flow path cross-sectional area (the actual flow path cross-sectional area taking into account flow path resistance). Because of the effect of the vortex, there is little air flow toward the outlet at the end of the casing in the direction of the rotary shaft, so there was a demand to reduce the effect of the vortex and increase the air volume.

The present invention was made in consideration of the above circumstances, and aims to provide a centrifugal blower that can suppress the growth of vortices that occur when air gets caught behind the bell mouth, ensure a smooth air flow, and increase the blower's air volume.

The present invention is a centrifugal blower comprising an impeller having a plurality of blades, which is connected to a rotating shaft and rotates to exhaust air in a centrifugal direction through the plurality of blades, and a casing that houses the impeller and has an outlet, the casing having a spiral section in which the distance between the inner peripheral surface of the impeller facing the plurality of blades and the rotating shaft gradually increases from the beginning of the winding to the end of the winding, the spiral section having an outer peripheral plate section that covers the outer peripheral side of the impeller, and a side plate section having the suction port in the center, the suction port having a bell mouth whose inner diameter decreases as it approaches the inside in the direction of the rotation axis, an annular protrusion section is provided radially outside the bell mouth and extends from the side plate section to the inside in the direction of the rotation axis with a gap therebetween, the annular protrusion section is concentric with the bell mouth, forms a space into which air flows between the bell mouth and the annular protrusion section, and has an axial height lower than that of the bell mouth.

The present invention also provides a centrifugal blower comprising an impeller having a plurality of blades, which is connected to a rotating shaft and rotates to exhaust air in a centrifugal direction through the plurality of blades, and a casing that houses the impeller and has an air outlet, the casing having a spiral section in which the distance between the inner peripheral surface of the impeller facing the plurality of blades and the rotating shaft gradually increases from the beginning to the end of the winding, the spiral section having an outer peripheral plate section that covers the outer peripheral side of the impeller, and a side plate section having an intake port in the center, the intake port having a bell mouth whose inner diameter decreases as it approaches the inside in the direction of the rotation axis, an annular protrusion section extending from the side plate section in the direction of the rotation axis at a distance from the bell mouth to the radially outer side of the bell mouth, the annular protrusion section being concentric with the bell mouth to form a space into which air flows between the bell mouth and the bell mouth, and having a notch at a location facing the air outlet.

The present invention makes it possible to suppress the growth of vortices that occur when air gets caught behind the bell mouth, ensuring a smooth air flow and increasing the blower's air volume.

1 is a plan cross-sectional view showing an air conditioner according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1 is a cross-sectional view showing a centrifugal blower according to an embodiment. 4 is a cross-sectional view taken along line IV-IV of FIG. 3. 4 is a cross-sectional view taken along line VV in FIG. 3. 1 is a perspective view of a centrifugal blower according to an embodiment, as viewed obliquely from the front. FIG. 1 is a perspective view of a centrifugal blower according to an embodiment, seen obliquely from behind; FIG. 1 is a side view showing a centrifugal blower according to an embodiment. FIG. 2 is a partial cross-sectional view of a casing in the embodiment. FIG. 2 is a partial cross-sectional view of a casing in the embodiment. FIG. 2 is a cross-sectional plan view of a casing in the embodiment.

1. Overall Structure of the Air Conditioner An air conditioner 1 according to an embodiment will be described with reference to Figures 1 to 5. In these figures, reference numeral 10 denotes a housing. The housing 10 has an air suction section 11 on the left end surface in the figures and an air blowing section 12 on the right end surface. The air suction section 11 and the air blowing section 12 are each a rectangular opening. A partition plate 13 is attached inside the housing 10 to divide it into a left chamber 10a and a right chamber 10b, and a centrifugal blower 100 is attached to the partition plate 13.

The centrifugal blower 100 has a casing 110 to which a fixed plate 111 is fixed. The fixed plate 111 is attached to the partition plate 13 with bolts, nuts, etc., so that the centrifugal blower 100 is disposed in the left chamber 10a, and the left chamber 10a and the right chamber 10b are sealed by the partition plate 13 and the fixed plate 111 to prevent air from the right chamber 10b from leaking into the left chamber 10a.

The centrifugal blower 100 is a sirocco fan that houses an impeller 150 in a casing 110 and is configured by connecting a rotating shaft 153 of a fan motor 152 to a disk-shaped main plate 151 of the impeller 150. A cylindrical blade portion 154 is attached to the main plate 151. The blade portion 154 is fixed to the main plate 151 by fixing one end of each of a plurality of blades 154b to a pair of annular members 154a, and the blade portion 154 is fixed to the main plate 151 by fixing the other end of the blade 154b to the main plate 151. The blades 154b are forward-facing blades, and the blade portion 154 rotates in a clockwise direction in FIG. 2. Note that the rotating shaft 153 is not shown in FIGS. 3 to 5.

A heat exchanger 160 attached to a bracket 14 fixed to the housing 10 is disposed in the right chamber 10b of the housing 10. The heat exchanger 160 dehumidifies, cools, or heats the air sent from the centrifugal blower 100 and releases it from the air outlet section 12. The heat exchanger 160 can also be disposed upstream of the centrifugal blower 100. In other words, the centrifugal blower 100 can be disposed in the right chamber 10b, and the heat exchanger 160 can be disposed in the left chamber 10a.

2. Configuration of the Centrifugal Fan The centrifugal fan 100 of the embodiment will be described with reference to Figures 3 to 11. In the following description, the direction of the rotating shaft 153 of the fan motor 152 will be referred to as the "axial direction", the direction perpendicular to the axial direction will be referred to as the "radial direction", and the direction of rotation about the rotating shaft 153 will be referred to as the "circumferential direction". Furthermore, the terms "upper" and "lower" refer to the top and bottom in Figure 3. Furthermore, the directions in which the air flows will be referred to as the "upstream side" and the "downstream side".

The casing 110 of the centrifugal blower 100 is formed by splitting the casing 110 into two parts along a plane perpendicular to the axial direction, injection-molding the parts with resin, and joining the molded parts by gluing, welding, or the like. The casing 110 has a side plate portion 120 that covers the side surface, and an outer peripheral plate portion 130 that covers the outer peripheral surface. The side plate portion 120 has an intake port 121 that guides air into the inner space of the blade portion 154, and the intake port 121 is a circular opening provided in a position facing the inner space of the blade portion 154.

The suction port 121 is concentric with the blade portion 154, and its inner diameter is set to be larger than the inner diameter of the blade 154b. A bell mouth 122 is formed at the edge of the suction port 121. The inner diameter of the bell mouth 122 gradually decreases toward the inside in the axial direction, and the air sucked into the suction port 121 increases in speed as it passes through the bell mouth 122. The bell mouth 122 is formed in a tapered shape or an arc-shaped cross section. The air sucked into the blade portion 154 passes between the blades 154b and is exhausted in the centrifugal direction of the blade portion 154.

A spiral section 131 (see FIG. 3), which is a spiral flow passage, is formed inside the outer peripheral plate section 130 of the casing 110. The spiral section 131 has a structure in which the part where the gap between the outer peripheral plate section 130 and the blade section 154 is smallest is the start of the winding P, and the gap (cross-sectional area) gradually increases as it progresses in the circumferential direction from there. For example, the spiral section 131 has a cross-sectional shape that follows an involute curve. Note that the cross-sectional shape of the spiral section 131 is not limited to an involute curve, and any spiral shape, such as an Archimedean spiral, can be used.

The spiral section 131 is shaped to follow an arbitrary curve up to the end of the spiral Q. That is, the cross-sectional shape of the spiral section 131 along the involute curve ends at the end of the spiral Q, and beyond the end of the spiral Q is a diffuser section 133 that forms a flow path leading to the air outlet 132, which is a rectangular opening. In the spiral section 131, the airflow becomes a swirling flow centered on the rotation axis 153, but in the diffuser section 133, the airflow becomes a linear airflow.

The diffuser section 133 has a fixed plate 111 fixed to the middle section located between the winding end Q side and the air outlet 132. The fixed plate 111 is a rectangular plate that protrudes in the vertical and horizontal directions from the side plate section 120 and the outer peripheral plate section 130. The fixed plate 111 is formed integrally with the casing 110 by injection molding, but it may also be made separately from the casing 110 and attached to the casing 110 by adhesive or other means.

As shown in FIG. 3, the section from the fixed plate 111 to the air outlet 132 has an expansion section 145 that is inclined upward with respect to the section upstream of the fixed plate 111. The distance between the expansion section 145 and the lower wall section 146 facing the expansion section 145 gradually increases from the winding end Q side toward the air outlet 132, and the flow path cross-sectional area formed by the side plate section 120, the expansion section 145, and the lower wall section 146 gradually increases toward the air outlet 132.

As shown in Figures 9 to 11, an annular protrusion 140 is formed on the radial outside of the bellmouth 122, extending in the axial direction with a gap from the bellmouth 122. Note that Figures 9 to 11 are partial cross-sectional views of the casing 110 divided in half along a plane perpendicular to the axial direction, and the opposite axial side of the figure is formed in the same way, making them symmetrical in the axial direction. Note that they may also be asymmetrical in the axial direction. The annular protrusion 140 is concentric with the bellmouth 122, and forms a space S between the bellmouth 122 and the space S into which air flows, with no other members entering the space S. Air flows into the annular protrusion 140 from between the tip of the annular protrusion 140 and the vane portion 154.

The axial height of the annular convex portion 140 from the side plate portion 120 to the tip is lower than the height of the bellmouth 122 from the side plate portion 120 to the tip. In other words, the distance from the tip of the annular convex portion 140 to the blade portion 154 is greater than the distance from the tip of the bellmouth 122 to the blade portion 154. This forms a gap between the blade portion 154 and the annular convex portion 140 through which air flows into the space S. In addition, the outer diameter of the annular convex portion 140 is smaller than the outer diameter of the annular member 154a of the blade portion 154. Furthermore, the annular convex portion 140 is formed on the base portion 141, which is one step higher than the side plate portion 120. As shown on the left side of FIG. 9, a part of the annular convex portion 140 extends directly axially inward from the side plate portion 120. In this way, the annular convex portion 140 is composed of a portion extending from the base portion 141 and a portion extending from the side plate portion 120. Note that a plate may be installed on the side plate portion 120 instead of the base portion 141.

The bellmouth 122 is formed around the entire circumference, but the annular protrusion 140 has a notch 142 at a location facing the air outlet 132. The notch 142 is formed over the entire height of the annular protrusion 140 from the tip to the base of the annular protrusion 140. In other words, the annular protrusion 140 is not formed around the entire circumference, and there is a portion where the annular protrusion 140 does not exist between the bellmouth 122 and the outer peripheral plate portion 130. The annular protrusion 140 may be formed around the entire circumference without providing the notch 142. In this way, the space S facing the notch 142 is open toward the air outlet 132.

As shown in FIG. 10, the annular protrusion 140 has a base 143 formed thereon that decreases in height in one or two steps toward the notch 142. The base 143 is provided from near the start of winding P toward the notch 142 at one end of the annular protrusion 140, and from near the end of winding Q toward the notch 142 at the other end. The base 143 provided from near the start of winding P is a single step, while the base 143 provided from near the end of winding Q is a two step step. Instead of the base 143, a slope that gradually decreases in height may also be formed.

3. Actions and Effects When the fan motor 152 rotates, the blade portion 154 rotates, and the action of the blades 154b draws air from the suction port 121. The drawn air passes through the gaps between the blades 154b inside the casing 110 and is discharged in the centrifugal direction, flows from the volute portion 131 to the diffuser portion 133, and is blown out from the air outlet 132.

Here, when the air sucked in from the bell mouth 122 is exhausted in the centrifugal direction by the vane portion 154, the air exhausted in the centrifugal direction collides with the outer peripheral plate portion 130 and flows axially outward, that is, between the bell mouth 122 on the side plate portion 120 side and the outer peripheral plate portion 130, and becomes a vortex. In the absence of the annular convex portion 140, a vortex with a diameter approximately equal to the radial distance between the bell mouth 122 and the outer peripheral plate portion 130 is formed at maximum. Since the region in which the vortex is formed does not contribute to the air flow toward the outlet 132, the cross-sectional area (effective flow path cross-sectional area) of the substantial flow path in which the air flow toward the outlet 132 in the volute portion 131 is formed becomes narrow. On the other hand, by providing the annular convex portion 140, the vortex is contained in the space S between the annular convex portion 140 and the bell mouth 122, and is suppressed from growing large. Therefore, the air flow radially outward from the annular convex portion 140 in the volute portion 131 is not hindered.

Generally, air sucked in from the suction port 121 is discharged along the main plate 151 into the inside of the volute 131 located radially outside the impeller 154, so the air volume is smaller on the outside of the volute 131 in the direction of the rotation axis (side plate 120 side) than in the center of the direction of the rotation axis. However, in the above embodiment, the flow of air sucked in from the suction port 121 is deflected toward the axial end side of the centrifugal blower by the action of the vortex generated in the space S between the annular protrusion 140 and the bell mouth 122. This ensures the air volume on the axial end side of the centrifugal blower. Therefore, in the above embodiment, the air volume can be increased.

However, downstream of the end of the spiral portion 131, the tongue portion 134 forcibly changes the air flow toward the outlet 132, and the vortex generated at the axial end side of the spiral portion 131 that did not contribute to the main flow mixes with the main flow and changes to a flow toward the outlet 132. That is, the cross-sectional area of the flow path (effective flow path cross-sectional area) where the air flow toward the outlet 132 is formed is larger than that of the spiral portion 131. Therefore, it is possible to allow the generation of vortexes between the bell mouth 122 and the outer peripheral plate portion 130, and there is no need to provide the annular protrusion 140 that suppresses the growth of the vortex, so the above embodiment has a notch 142 at the location facing the outlet 132. The notch 142 can further expand the substantially effective flow path cross-sectional area where the air flow toward the outlet 132 in the spiral portion 131 is formed, contributing to an increase in air volume.

In addition, in the above embodiment, the height of the end of the annular protrusion 140 on the side of the notch 142 decreases stepwise as it approaches the notch 142, so that the effective flow passage cross-sectional area of the spiral portion 131 gradually increases as it approaches the notch 142, allowing air to flow smoothly while achieving the above effect.

In the above embodiment, the outer diameter of the annular protrusion 140 is smaller than the outer diameter of the annular member 154a of the impeller 154, so it does not impede the smooth flow of air generated by the impeller 154.

In addition, since the annular protrusion 140 is made up of a portion extending from the base 141 and a portion extending from the side plate 120, for example, by increasing the depth of the space S on the side closer to the air outlet 132, the above-mentioned effect of increasing the flow path cross-sectional area and increasing the air volume can be reliably obtained. Note that multiple bases 141 can be provided at intervals from each other in the circumferential direction.

The annular protrusion 140 can extend axially inward from the side plate 120 around the entire circumference. The deeper the space S, the larger the vortex that can be accommodated, and the larger the effective flow area can be, which increases the maximum airflow.

4. Modifications The present invention is not limited to the above-described embodiment, and various modifications are possible as follows.
i) It is possible to employ either a configuration in which the height of the annular convex portion 140 is made lower than the height of the bellmouth 122, or a configuration in which the annular convex portion 140 has a notch 142 at a location facing the air outlet 132. In other words, even in a configuration in which the notch 142 is not present, the effect of suppressing the growth of a vortex due to the provision of the annular convex portion 140 can be obtained.

ii) An impeller having multiple blades fixed to a main plate can be used in place of the blade portion 154 of the impeller 150.

iii) Although the air conditioner 1 uses two impellers 150, the number of impellers 150 may be one or three or more.
iv) The air conditioner 1 can be equipped with a humidifier and an air filter.

1...air conditioner, 10...casing, 10a...left chamber, 10b...right chamber, 11...air intake section, 12...air outlet section, 13...partition plate, 14...bracket, 100...centrifugal blower, 110...casing, 111...fixed plate, 120...side plate section, 121...intake port, 122...bell mouth, 130...peripheral plate section, 131...volute section, 132...outlet port, 133...diff user portion, 134... tongue portion, 140... annular convex portion, 141... base portion, 142... notch, 143... base portion, 145... expansion portion, 146... bottom wall portion, 150... blower fan, 151... main plate, 152... fan motor, 153... rotating shaft, 154... blade portion, 154a... annular member, 154b... blade, 160... heat exchanger, P... start of winding, Q... end of winding, S... space.

The present invention is a centrifugal blower comprising: an impeller having a plurality of blades, connected to a rotating shaft and rotating to exhaust air in a centrifugal direction through the plurality of blades; and a casing that houses the impeller and has an air outlet, wherein the casing has a spiral portion in which the distance between an inner circumferential surface of the impeller facing the plurality of blades and the rotating shaft gradually increases from the start of winding to the end of winding, the spiral portion comprises an outer peripheral plate portion that covers the outer circumferential side of the impeller, and a side plate portion having an intake port in its center, the intake port having a bell mouth whose inner diameter decreases as it extends inward in the direction of the rotation axis, and a ring-shaped protrusion is provided radially outward from the bell mouth and extending from the side plate portion inward in the direction of the rotation axis with a gap therebetween, the ring-shaped protrusion is concentric with the bell mouth to form a space into which air flows between the bell mouth and the ring-shaped protrusion, and has an axial height that is lower than the bell mouth, and the ring-shaped protrusion has a notch at a location facing the air outlet .

Claims (9)

an impeller having a plurality of blades and connected to a rotating shaft and rotating to exhaust air in a centrifugal direction through the spaces between the plurality of blades;
a casing that houses the impeller and has an outlet;
Equipped with
the casing includes a volute portion in which a distance between an inner circumferential surface of the impeller facing the plurality of blades and the rotation shaft gradually increases from a start of winding to an end of winding,
The volute portion includes an outer peripheral plate portion that covers an outer peripheral side of the impeller, and a side plate portion that has a suction port at a central portion,
The suction port includes a bell mouth having an inner diameter that decreases toward the inside in the rotation axis direction,
an annular protrusion extending from the side plate portion toward an inner side in the rotation axis direction is provided at a distance from the bell mouth to an outer side in the radial direction of the bell mouth,
The annular convex portion is concentric with the bell mouth to form a space between the bell mouth and the annular convex portion into which air flows, and has an axial height shorter than that of the bell mouth. The centrifugal blower according to claim 1, wherein the annular protrusion has a notch at a location facing the air outlet. an impeller having a plurality of blades and connected to a rotating shaft and rotating to exhaust air in a centrifugal direction through the spaces between the plurality of blades;
a casing that houses the impeller and has an outlet;
Equipped with
the casing includes a volute portion in which a distance between an inner circumferential surface of the impeller facing the plurality of blades and the rotation shaft gradually increases from a start of winding to an end of winding,
The volute portion includes an outer peripheral plate portion that covers an outer peripheral side of the impeller, and a side plate portion that has a suction port at a central portion,
The suction port includes a bell mouth having an inner diameter that decreases toward the inside in the rotation axis direction,
an annular protrusion is provided on the radially outer side of the bell mouth at a distance from the side plate portion, the annular protrusion extending in the direction of the rotation axis;
The annular convex portion is concentric with the bell mouth to form a space between the bell mouth and the annular convex portion, into which air flows, and has a notch at a location facing the air outlet. The centrifugal blower according to claim 2 or 3, wherein the notch extends over the entire height of the annular protrusion in the direction of the rotation axis from the tip to the base of the annular protrusion. The centrifugal blower according to claim 2 or 3, wherein the height of the annular protrusion decreases toward the cutout side. The centrifugal blower according to claim 2 or 3, wherein the outer diameter of the annular protrusion is smaller than the outer diameter of the annular member of the impeller. The centrifugal blower according to claim 2 or 3, wherein the annular protrusion is provided on a plate portion or a base portion provided on the bottom surface of the side plate portion. The centrifugal blower according to claim 7, wherein the height of the plate portion or base portion provided on the bottom surface of the side plate portion in the direction of the rotation axis varies in the circumferential direction at the outer periphery of the bell mouth. An air conditioner having a housing including the centrifugal blower according to claim 2 or 3 and a heat exchanger.

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