JPH0719195A - Multiblade fan - Google Patents

Abstract

PURPOSE:To suppress noise generated in association with air blasting operation by forming a bell-mouth, forming a suction port on the suction face of a casing, into protrusive shape of semicircular cross section, and forming the spiral end of a spiral casing into linear shape. CONSTITUTION:An impeller 10 is rotated by the driving of a motor so that air is sucked into a casing 20 from a suction port 25, boosted by the impeller 10 and discharged from a discharge port 24 to perform air blasting operation. The suction air (a) is sucked smoothly along a protrusive bell-mouth of semicircular cross section to suppress noise, and the flow of the suction air is changed into the radial direction from the axial direction. The spiral end 22a of a spiral casing 22 is formed into linear shape. Noise generated in association with the discharge of blast air can be thereby reduced in comparison to a conventional one with the spiral end 22a contracted into a spiral shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-blade fan used as a blower such as an air conditioner, a hot water heater, a ventilation blower, and the like, and relates to noise reduction during blow operation of the multi-blade fan.

[0002]

2. Description of the Related Art Centrifugal multi-blade fans such as a turbo fan and a sirocco fan are generally used for blowers such as an indoor unit of an air conditioner and a forced combustion type gas water heater. Such a multi-blade fan is configured by accommodating an impeller in which a large number of blades are annularly arranged in a spiral casing, is driven by a motor to rotate the impeller, and sucks air from the suction port into the casing. Then, the pressure is increased by the impeller, and the air is discharged from the discharge port to perform the blow operation. On the other hand, for household and industrial equipment incorporating such a blower, it is strongly desired to reduce the driving noise in consideration of the surrounding environment where the equipment is installed and the improvement of comfort of use. Came.

[0003]

In response to such a situation, in recent years, research on suppression of operating noise of a multi-blade fan incorporated in these devices has been advanced, and various proposals have been made, but satisfactory results are not always obtained. Not obtained. The present invention is intended to solve these problems, and provides the countermeasures obtained as a result of repeated testing and research on the shape of each member such as the casing, the impeller, and the blades, and the arrangement configuration thereof, The purpose is to reduce the operating noise of a multi-blade fan.

[0004]

In order to achieve this object, the present invention provides a spiral-shaped impeller in which a large number of blades are annularly arranged by being sandwiched between a disc-shaped main plate and an annular side plate. In a multi-blade fan housed in a casing, a bell mouth forming a suction port on a suction surface of the casing is formed in a protruding shape having a semicircular cross section, and a spiral end of the spiral casing is formed in a straight line. Then, the inner ends of the blades made of steel plate are bent and joined in the direction of rotation, or the inner ends of the blades made of resin are made thick and formed into a ball shape. Further, the impeller is housed in the casing with the main plate side being close to the bottom surface side of the casing, and a gap L is formed between the side plate side and the suction surface to form a multi-blade fan.

[0005]

[Function] The bell mouth is formed in a semi-circular projecting shape to reduce noise caused by suction of air at the suction port, and the spiral end of the spiral casing is formed in a straight line to reduce noise caused by discharge of air. It was confirmed to do. Also, the inner ends of the blades made of steel plate are bent and joined in the direction of rotation, or the inner ends of the blades made of resin are made thicker and formed into a ball shape, which accompanies the delivery from inside to outside of the impeller. It was confirmed that noise is suppressed and a space L is formed between the side plate side and the suction surface, the collision between the suction air and the backflow air is mitigated at this location, and both are merged to effectively suppress the noise. It was The configuration of the present invention will be specifically described below with reference to the embodiments of the drawings.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings show an embodiment of the present invention in which an impeller (10) is housed in a spiral casing (20), and the impeller (1
It is a sirocco fan that carries out blow operation by rotation of 0). In the drawing, a disk-shaped main plate (13) and an annular side plate (1
A large number of blades (11) are arranged in an annular shape with both ends sandwiched by 4), and the impeller (10) is formed in a cylindrical shape. Each blade (11) made of a substantially rectangular steel plate is gently curved with a specific curvature, and its inner end (12) is bent and joined in the rotational direction (see FIG. 3). Further, as another embodiment, when the blades are formed of synthetic resin, the inner ends (12a) of the resin blades (11a) may be thickened to form a ball shape (see FIG. 4). .

The casing (20) has one side plate, that is, a suction surface (21) having a suction port (25) for sucking blown air, a spiral casing (22) bent into a spiral shape, and the other side plate, that is, A discharge port (24) that joins the bottom surface (23) and is formed in a spiral shape to discharge blast air.
Is formed so as to project at the end. The suction port (25) is
A bell mouth (26) having a semicircular cross section is formed on the week edge to form a suction surface (21). The spiral end (22a) of the spiral casing (22) is formed in a straight line without being narrowed, and an angle at which the spiral end (22a) intersects with the discharge port (24), that is, the spiral portion (2).
7) is formed at an angle of 90 degrees on the plane. Then, the impeller (10) is moved to the bottom (2
The main plate (13) side is housed in the casing (20) close to the bottom face (23) side so as not to come into contact with the side plate (14) side and the suction surface (2).
A gap L as large as possible is formed between the impeller (1) and the motor (1), and the impeller (10) is connected to the output shaft (30) of the motor.

In this embodiment, the impeller (10) is rotated by driving the motor, air is sucked into the casing (20) through the suction port (25), and the pressure is increased by the impeller (10).
The air is discharged from the discharge port (24) to perform a blowing operation. here,
The suction air a is smoothly sucked along the protruding bell mouth (26) having a semicircular cross section to suppress noise, and the suction air changes its flow from the axial direction to the radial direction. Then, the inner end (12) is bent in the rotational direction so that the tip of the blade (11) is rounded, and the noise of the blown air b from the inside to the outside of the impeller (10) is reduced. Similar effects can be obtained when the inner ends (12a) of the resin blades (11a) are thickened and formed into a ball shape. And, by forming the spiral end (22a) of the spiral casing (22) in a linear shape, an experimental result of reducing the noise associated with the discharge of the blast air as compared with the conventional product in which the spiral end (22a) is narrowed in a spiral shape. was gotten.
Furthermore, the main plate (13) side is close to the bottom surface (23) side of the casing (20), and the side plate (14) side and the suction surface (21).
By forming a space L as large as possible between the suction air a and the backflow air c that tries to return to the suction port (25) side, it is possible to reduce the noise by combining the two. it can.

It should be noted that the multi-blade fan with various specifications
As a result of measuring the noise at a position separated by m, the characteristics shown in FIG. 5 could be obtained. Here, line A is a conventional product without special noise countermeasures, line B is the same specifications, but the bell mouth (26) has a semicircular projecting shape and the spiral end (22a) is formed in a straight line. In the case of line C, when the inner ends (12) of the blades (11) made of steel plate are further bent and joined in the rotational direction, line D further has the main plate (13) side on the casing ( 20) close to the bottom surface (23) side, and a distance L between the side plate (14) side and the suction surface (21).
Is formed. Under each condition, the noise increases as the rotation speed increases, but it was confirmed that the noise can be surely suppressed by implementing the noise countermeasure of the present invention.

[0010]

EFFECTS OF THE INVENTION The multi-blade fan of the present invention blows air by forming the casing (20), the impeller (10), the blades (11), and other members, and the arrangement of these members as described above. It is possible to suppress the noise caused by the operation and to reduce the operation noise of the multi-blade fan. Moreover, compared to the conventional structure, the structure is not particularly complicated, each member is easily formed by press working, and the labor for manufacturing is not complicated, and the operation noise can be reliably reduced. However, it has practical effects such as being manufactured at the same cost as the conventional one.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory view showing an arrangement state of blades made of a steel plate.

FIG. 4 is an explanatory view showing an arrangement state of resin blades.

FIG. 5 is a noise characteristic diagram of the multi-blade fan of the present invention and a conventional product.

[Explanation of symbols]

 10 Impeller 11 Blade 11a Blade 12 Inner end 12a Inner end 13 Main plate 14 Side plate 20 Casing 21 Suction surface 22 Swirl casing 22a Swirl end 23 Bottom 25 Suction port 26 Bellmouth

Claims (4)

[Claims] 1. A disc-shaped main plate (13) and an annular side plate (1)
In a multi-blade fan in which an impeller (10) having a large number of blades (11) arranged in an annular shape sandwiched with 4) is housed in a spiral casing (20), a suction surface ( 21) a bell mouth (2) forming a suction port (25)
6) A multi-blade fan in which 6) is formed in a semi-circular projecting shape and the spiral end (22a) of the spiral casing (22) is formed in a straight line. 2. Inner ends (12) of each blade (11) made of steel plate
The multi-blade fan according to claim 1, wherein the fan is bent and joined in a rotating direction. 3. The inner end (12) of each blade (11a) made of resin
The multi-blade fan according to claim 1, wherein a) is thickened and formed into a ball shape. 4. The main plate (13) side is close to the bottom surface (23) side of the casing (20), the impeller (10) is housed in the casing (20), and the side plate (14) side and the suction surface (21). )
The multi-blade fan according to claim 1, 2 or 3, wherein an interval L is formed between the fan and the fan.