JP3966247B2 - Centrifugal fan - Google Patents

Description

  The present invention relates to a centrifugal fan used in a ventilation fan, an air conditioner, a dehumidifier, a humidifier, or an air cleaner.

  Conventionally, this type of centrifugal fan is known to have two types of blades having different blade inlet and outlet angles. (For example, refer to Patent Document 1).

  Hereinafter, this type of centrifugal fan will be described with reference to FIGS.

  As shown in the figure, a bell mouth-like suction port 101 is formed on one side, and a main plate that is perpendicular to the rotation axis and is flat inside a spiral casing 104 having an orifice 102 and a discharge port 103 having an inner diameter equivalent to the fan inner diameter. 105, a plurality of blades 106 disposed above and below the main plate 105, ring-shaped side plates 107 at both ends of the blade, and air from the upper blade 106a side to the lower blade 106b side on the main plate 105 Ventilation holes 108 for circulation are provided, and the blade inlet angle θ1 of the upper blade 106a and the lower blade 106b and the blade outlet angle θ2 of the upper blade 106a and the lower blade 106b have different shapes.

With the above configuration, when the centrifugal fan 111 is rotated by applying a driving force from the motor 110 to the shaft 109, the suction air 112 passes through the suction port 101 of the orifice 102, flows into the blade inlet portion 113, and passes between the blades 106. When the pressure is increased and the gas flows out from the blade outlet 114 and passes through the spiral casing 104, the dynamic pressure is gradually converted into a static pressure and discharged to the discharge port 103. In the centrifugal fan 111, the load (static pressure) on the centrifugal fan 111 varies depending on the length of the discharge duct connected to the discharge port 103, and the large air volume / low static pressure area to the small air volume / high static pressure area. Will have various operating points.
Japanese Patent Application Laid-Open No. 2001-271791

  In such a conventional centrifugal fan, blades with different inlet and outlet angles at the upper and lower parts of the main plate in order to expand the main flow range biased to the main plate toward the side plate at the operating point in the high flow rate and low static pressure region. However, because the main flow flows through the ventilation holes to the lower blade, when the main flow passes through the ventilation holes, collision with the main plate and an increase in the main flow velocity occur, and the lower blades The flow rate of the blade is increased, the blade surface is easily peeled off, the total pressure efficiency is low, the noise is high, and the main flow is from the blade on the main plate side to the side plate at the operating point in the small flow rate and high static pressure range. However, if the exit angle of the upper blade is the same from the main plate side to the side plate side, the difference from the outflow angle becomes large, the separation area near the blade exit portion is expanded, and noise is generated accordingly. Easy There is a problem, it is required to be improved aerodynamic performance at a lower noise.

  The present invention solves such a conventional problem, and at the operating point in a large flow rate / low static pressure region, the main flow range biased to the main plate is expanded to the side plate side, and the flow velocity between the blades in the blade on the main plate side is increased. By reducing the turbulent flow noise associated with separation and reducing the difference between the outlet angle of the blade outlet on the side plate side and the outflow angle at the operating point in the small flow rate and high static pressure range, An object of the present invention is to provide a centrifugal fan that can reduce the separation region of the blade outlet and reduce the turbulent noise associated therewith.

  In addition, at the operating point in the large flow rate and low static pressure region, the main flow is biased toward the main plate, so the flow velocity between the blades on the main plate side is increased, the blade surface is liable to peel off, the total pressure efficiency is low, and noise is generated. There is a problem that it is large, and at the operating point in the low flow rate and high static pressure region, the main flow shifts from the blade on the main plate side to the blade on the side plate side. However, since it flows backward to the back side of the main plate and stays in a stagnation state, the blade on the main plate side does not perform effective work and aerodynamic performance is reduced.

  In addition, when manufacturing a centrifugal fan, if the outer diameter of the blade is less than or equal to the outer diameter of the main plate, there is a problem that die cutting becomes complicated and costly, and it takes time to manufacture. It is required to be able to improve.

  The present invention solves such a conventional problem, and reduces the increase in the flow velocity between the blades on the main plate side at the operating point in the large air volume / low static pressure region, and reduces the turbulent noise caused by the separation. In addition, at the operating point in the low flow rate and high static pressure range, the work of the blade on the main plate side is increased to prevent the aerodynamic performance from being lowered. An object of the present invention is to provide a centrifugal fan that can make a centrifugal fan with high efficiency and low noise.

  Also, at the operating point in the high flow rate / low static pressure region, the main flow is biased toward the region away from the suction port, so the flow rate between the blades in the region away from the suction port is increased and the blade surface is likely to peel off. There is a problem that the total pressure efficiency is low and noise is large, and at the operating point in the small flow rate and high static pressure region, the main flow moves from a region away from the suction port to a region close to the suction port, but the inlet angle of the blade Is the same from the main plate side to the side plate side, the difference between the inflow angle and the blade inlet angle becomes large, and there is a problem that collision and separation phenomenon at the blade inlet portion and noise accompanying it are likely to occur, and the noise is lower. Therefore, it is required to improve the aerodynamic performance.

  The present invention solves such a conventional problem, and at the operating point in a large flow rate / low static pressure region, the collision / peeling phenomenon at the blade inlet portion is reduced and it is biased to a region away from the suction port. The main flow range can be expanded to a region close to the suction port, the increase in the flow velocity between the blades in the region away from the suction port can be mitigated, and turbulent noise caused by separation can be reduced. By reducing the difference between the inlet angle and the inlet angle of the blade inlet in the region close to the suction port at the operating point, the centrifuge that can reduce the collision / separation phenomenon and accompanying turbulence noise at the blade inlet The purpose is to provide fans.

  In addition, at the operating point in the high flow rate and low static pressure region, the main flow is biased toward the blade ventral region, so separation on the blade back side is likely to occur, the total pressure efficiency is reduced, and turbulent noise and noise are generated. There is a problem that it occurs, and it is required that aerodynamic performance can be improved with lower noise.

  The present invention solves such a conventional problem, and between the blades, the main flow range biased to the blade ventral side is expanded to the blade back side region, the flow between the blades is made uniform, and the turbulent flow noise accompanying the separation. It is an object of the present invention to provide a centrifugal fan that can reduce efficiency reduction.

In order to achieve the above-described objective, the centrifugal fan of the present invention is configured such that a part or all of the blade outlet portion is moved from the main plate side in a state where the blade outlet portion on the main plate side is advanced in the rotational direction from the blade outlet portion on the side plate side. Twist toward the side plate side to have different exit angles, have a main plate with an outer diameter equal to or less than the position of the starting point of the centrifugal fan blade, and the main plate side of the blade is the opposite side plate of the main plate It has it to a side end surface.

  According to the present invention, at the operating point in the large air volume / low static pressure region, the increase in the flow velocity between the blades on the main plate side is alleviated and the turbulent noise caused by the separation is reduced, and at the operating point in the small flow rate / high static pressure region, The work of the blade on the main plate side is increased to prevent aerodynamic performance from being deteriorated, and a centrifugal fan having high efficiency and low noise can be produced in a low cost in a short time by using a simple die cutting method.

According to the present invention , the centrifugal fan blade has a main plate having an outer diameter equal to or less than that of the wing start point of the blade of the centrifugal fan, and the main plate side of the blade extends to the opposite side plate side end surface of the main plate. Improves the total pressure efficiency of the fan by reducing collisions, separation, and boundary layer development, working on the blade surface efficiently. In addition, it suppresses the generation of turbulent noise caused by collision, separation, and boundary layer development.

  Further, it is possible to provide a centrifugal fan that has an effect of being able to produce a centrifugal fan in a short time and at a low cost.

  The centrifugal fan blade has a main plate with an outer diameter equal to or less than the starting point of the blade, and the main plate side of the blade is up to the end surface on the opposite side of the main plate. Since the ventilation path near the main plate is enlarged, it becomes easy to flow into the blade on the main plate side, and the flow velocity is reduced, so that it is possible to prevent the collision at the blade inlet and the blade surface, the separation phenomenon and the accompanying noise generation. .

  In addition, in the small air volume / high static pressure region, the work of the blade on the main plate side can be increased by reducing the stagnation of the main plate on the back side.

  Further, since there is no main plate in the blade portion of the blade, a centrifugal fan can be produced at a low cost and in a short time using a simple die cutting method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

( Reference Example 1)
FIG. 1 is a side sectional view of a centrifugal fan and a casing in Reference Example 1, FIG. 2 is a sectional view of the main part of the blade shape of the centrifugal fan, and a diagram showing the flow of air, and FIGS. FIG. 4 and FIG. 5 showing the original are performance characteristic diagrams in this reference example .

  In addition, the same code | symbol is used about the same structure as a prior art example (FIGS. 10-12), and the description is abbreviate | omitted.

  1 and 2, a part or all of the blade outlet portion 1 is moved from the main plate 2 side to the side plate 3 side in a state in which the blade outlet portion on the main plate 2 side advances in the rotational direction from the blade outlet portion 1 on the side plate 3 side. By turning sequentially, the different exit angles β2 are obtained. With the above configuration, at the operating point in the large flow rate / low static pressure region, the main flow range 4 that is biased toward the main plate 2 is expanded to the side plate 3 side, and the increase in the flow velocity between the blades in the blade 5 on the main plate 2 side is alleviated and In addition to reducing the flow noise and reducing the difference between the outlet angle β2 and the outlet angle δ of the blade outlet part 1 on the side plate 3 side at the operating point in the small flow rate and high static pressure region, the separation region of the blade outlet part 1 And turbulent noise associated therewith can be reduced.

  Detailed specifications of the blade 5 will be described with reference to FIGS. The distance between the twist start position of the blade 5 and the rotating shaft: X, fan inner diameter: D1, fan outer diameter: D2 is D1 / 2 <X ≦ D1 / 2 + 0.9 (D2-D1) / 2, axial twist The distance from the side plate 3 at the start position: Y and the blade height: H are configured such that 0.2H <Y ≦ H.

FIG. 4 shows a comparison of performance characteristics between the reference example and the conventional example. In this reference example, the noise characteristics and the total pressure efficiency are improved over the entire region of the air volume-static pressure characteristics. FIG. 5 shows a comparison of frequency analysis of noise at 0 Pa-410 m ³ / h. In this reference example, the sound pressure level in the vicinity of 2000 Hz is greatly reduced.

(Embodiment 1 )
FIG. 6 is a side sectional view of the centrifugal fan and the casing according to the first embodiment of the present invention, and FIG. 7 is a diagram showing the specifications of the blade and the main plate.

  In addition, the same code | symbol is used about the same structure as a prior art example (FIGS. 10-12), and the description is abbreviate | omitted.

  6 and 7, the blade 5 has a main plate 2 having an outer diameter D0 equal to or less than the distance X between the starting point of the blade 5 and the rotation axis, and the main plate 2 side of the blade 5 is the opposite side plate of the main plate 2. It has up to the side end face 6.

  With the above configuration, at the operating point in the large air volume and low static pressure region, the increase in the flow velocity between the blades on the main plate 2 side is reduced, and the turbulent noise caused by the separation is reduced, and the operating point in the small flow rate and high static pressure region. To increase the work of the blade 5 on the main plate 2 side and prevent the aerodynamic performance from being lowered, and to enable the low-cost, short-time, high-efficiency, low-noise centrifugal fan 7 to be created using a simple die cutting method. Can do.

( Reference Example 2 )
FIG. 8 is a side view of the centrifugal fan and the casing in Reference Example 2 .

  In addition, about the same structure as a prior art example (FIGS. 10-12), the same code | symbol is used and the description is abbreviate | omitted.

  In FIG. 8, the blade 5 has a taper shape 8 such that the inner diameter of the blade 5 increases from the main plate 2 toward the side plate 3, and the fan inner diameter D1 on the side plate 3 side and the inner diameter of the orifice 102 are increased. In the low static pressure region, the axial flow velocity when passing through the orifice 102 is reduced, the radial flow when flowing into the blade inlet 9 is promoted, and the effective work area of the blade 5 on the main plate 2 side becomes the side plate 2 Enlarged to the side. Accordingly, the flow rate between the blades can be relatively reduced, and the peeling and the boundary layer development on the blade surface can be further suppressed.

( Reference Example 3 )
FIG. 9 is a view showing the state of the back surface of the blade.

  In FIG. 9, the surface of the back side 10 of the blade 5 is roughened or has a large number of irregularities. With the above configuration, the main flow range biased to the ventral side 11 of the blade 5 is expanded to the back side 10 region of the blade 5 between the blades, and the flow between the blades is made uniform to reduce the turbulent noise and the reduction in efficiency due to separation. be able to.

  The centrifugal fan according to the present invention reduces the collision / separation / boundary layer development between the blades, the work on the blade surface is efficiently performed, the total pressure efficiency of the fan is improved, and the collision / separation / boundary layer is improved. It has the effect of suppressing the generation of turbulent noise generated by development and suppressing the generation of turbulent noise generated by separation from the blade back side and development of the boundary layer. Ventilation blower, air conditioner, dehumidifier It is useful as a centrifugal fan used in a humidifier or an air cleaner.

Side sectional view of centrifugal fan and casing of Reference Example 1 Cross-sectional view of the main part of the blade shape of the centrifugal fan (A) Cross-sectional view of essential parts showing blade specifications of the centrifugal fan (b) Side cross-sectional view of relevant parts showing blade specifications Performance characteristics of centrifugal fan Performance characteristics of centrifugal fan Side sectional view of the centrifugal fan and casing of Embodiment 1 of the present invention Cross-sectional side view of essential parts showing specifications of the blade and main plate of the centrifugal fan Side sectional view of centrifugal fan and casing of Reference Example 2 Illustration of the back surface of the blade of Reference Example 3 Side sectional view of a conventional centrifugal fan and casing Cross section of the main part Top view of the main part

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blade exit part 2 Main plate 3 Side plate 4 Main flow range 5 Blade 6 Opposite side plate side end surface 7 Centrifugal fan 8 Tapered shape 9 Blade inlet part 10 Blade back side β1 Inlet angle β2 Outlet angle δ Outlet angle D1 Fan inner diameter D2 Fan outer diameter X Twist The distance between the starting position of the rotation axis and the rotating shaft H Blade height Y The distance from the side plate at the axial twisting starting position 101 Suction port 102 Orifice 103 Discharge port 104 Casing 105 Main plate 106 Blade 106a Upper blade 106b Lower blade 107 Side plate 108 Ventilation hole θ1 Inlet angle 109 Shaft θ2 Outlet angle 110 Motor 111 Centrifugal fan

Claims (2)

A bell mouth that forms a suction port on one side, an annular side plate inside a spiral casing having an orifice having an inner diameter equivalent to the fan inner diameter and a discharge port, and a substantially frustoconical shape that protrudes toward the side plate It has a plurality of blades attached so as to be sandwiched by a main plate having a throttle portion, and a part or all of the blade outlet portion is in a state where the blade outlet portion on the main plate side is advanced in the rotation direction more than the blade outlet portion on the side plate side. A centrifugal fan having different exit angles by sequentially twisting from the main plate side to the side plate side, and having a main plate with an outer diameter equal to or less than the position of the twist start point of the blade of the centrifugal fan , centrifugal fans that the main plate side blade Yusuke to counter-plate side end face of the main plate. 2. The centrifugal fan according to claim 1 , wherein the outer diameter of the main plate is D <b> 0, the distance between the twist start position of the blade and the rotation shaft is X, and the fan inner diameter is D <b> 1 .

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