JP5332479B2 - Centrifugal blower - Google Patents

Description

  The present invention relates to a centrifugal blower used for a ventilation blower or the like.

  Conventionally, this type of centrifugal blower is used for a ceiling-embedded ventilation fan or the like, and is known in which an opening different from a suction casing having a bell mouth-shaped suction port is provided in an opening on one surface of an outer shell ( For example, see Patent Document 1).

  Hereinafter, the centrifugal blower will be described with reference to FIG.

  As shown in FIG. 12, an outer shell 101 having an open surface, an electric motor 104 having an impeller 103 fixed to a top surface 102 in the outer shell 101, a casing 105 surrounding the periphery of the impeller 103, and a suction port having a suction port 106. A centrifugal blower including a casing 107 is provided with an orifice 109 having an opening 108 that is equal to or smaller than the suction port 106, and a lower end 110 of the suction casing 107 and an end 111 of the orifice 109 with a gap 112 having a gap dimension i therebetween. A resonance space 113 is formed. Further, a grill 114 and a discharge port 115 provided on one side of the outer shell 101 are provided on one surface of the orifice 109.

  In the above configuration, when the impeller 103 rotates, the intake air passes from the grill 114 through the opening 108 of the orifice 109, enters the impeller 103 through the suction port 106 of the suction casing 107, and is pressurized by the impeller 103. And discharged from the discharge port 115. At this time, rotational noise generated when the pressure is increased by the impeller 103, turbulent noise due to vortex generated when passing through the casing 105, and sound waves of noise generated in the casing 105 are radiated from the suction port 106, and A part of the light enters the resonance space 113 from the gap 112. Among the incident sound waves, the sound waves having a frequency specified by the volume and shape of the resonance space 113 undergo air column resonance in the resonance space 113 and are resonated.

Japanese Patent No. 3279834

  In such a conventional centrifugal blower, the operating state of the centrifugal blower changes depending on the length of the exhaust duct installed at the discharge port 115 during construction of the centrifugal blower, and the frequency characteristics of the generated noise change. There is a problem that the effect of reducing noise due to resonance silencing is reduced, and the optimum opening diameter is set for the frequency characteristics of noise generated from the suction port 106. Therefore, it is required to enhance the effect of resonance muffling.

  Further, the resonance silencing effect is higher as the diameter of the suction port 106 is the same as the opening diameter, and the resonance silencing effect is lower as the opening diameter is larger than the diameter of the suction port 106. When the diameter of the opening is small, the velocity of the wind that contacts the orifice 109 increases as the diameter of the opening becomes smaller, and there is a problem that the orifice 109 itself becomes a noise generation source. The orifice 109 having a small diameter is required to enhance the effect of resonance mute and reduce noise.

  The present invention solves such a conventional problem, the opening diameter of the orifice can be changed, and the optimum opening diameter is set for the frequency characteristics of the noise radiated from the suction port. An object of the present invention is to provide a centrifugal blower that can enhance the effect of silencing, enhance the effect of resonance silencing with an orifice having a small opening diameter as much as possible while reducing the noise generation from the orifice itself, and reduce the noise. Yes.

In order to achieve the above object, the centrifugal blower of the present invention includes an electric motor in which an impeller is connected to an outer frame having an opening so as to be rotatable about a rotation shaft, and a suction port that surrounds the periphery of the impeller. A casing, an orifice having an opening communicating with the opening of the outer frame, and a gap between a lower end of the casing and an end of the orifice, and a resonance space and a gap formed by the orifice A centrifugal blower that resonates and muffles the noise emitted from the suction port, and changes the opening diameter so as to minimize the noise value with respect to the change in the noise emitted from the suction port. It is a blower.

By this means , the opening diameter is changed so as to minimize the noise value with respect to the change in noise generated from the centrifugal blower , so that the sound deadening effect by the orifice works strongly and the noise can be reduced. A blower is obtained.

  Another means is a centrifugal blower characterized in that the opening has a bell mouth shape.

  By this means, since air can be smoothly guided to the casing, a centrifugal blower capable of reducing noise can be obtained.

  Another means is a centrifugal blower characterized in that the opening diameter is automatically changed.

  By this means, since the opening diameter is automatically changed even after the centrifugal blower is installed, the noise generated from the centrifugal blower can be accurately reduced by the silencing effect of the orifice, and the noise from the orifice itself The effect of the resonance muffling can be enhanced with an orifice having a small opening diameter as much as possible while alleviating the generation, and a centrifugal blower capable of reducing noise can be obtained.

  Another means is a centrifugal blower characterized in that it has noise detection means for measuring noise radiated from the opening, and the opening diameter is changed so as to minimize the measured noise value. It is.

  By this means, the diameter of the opening can be changed so that both the mitigation of noise generated from the orifice itself and the strong silencing effect by the orifice can be achieved, so that a centrifugal blower capable of reducing noise can be obtained.

  Further, the other means is provided with a rotational speed detecting means for measuring the rotational speed of the impeller, and is changed to an opening diameter at which a strong silencing effect is exerted with respect to a noise frequency caused by the rotational speed. A centrifugal blower is used.

  By this means, by changing the opening diameter, the frequency at which the silencing effect due to the orifice acts strongly matches the frequency of the noise caused by the rotation speed, so that the silencing effect can be exerted strongly and noise can be reduced. A centrifugal blower is obtained.

  Another means is a centrifugal blower characterized in that the orifice has an orifice outer wall extending in the rotation axis direction, and the outer wall is a cylinder concentric with the opening.

  By this means, the distance between the gap portion and the outer wall of the orifice is constant, so that a strong silencing effect is exerted on one frequency, and a centrifugal blower capable of reducing noise is obtained.

According to the present invention, the opening diameter can be changed, and the opening diameter is set so as to minimize the noise value with respect to the frequency characteristics of the noise radiated from the suction port, thereby enhancing the effect of resonance silencing. In addition, it is possible to provide a centrifugal blower capable of reducing the noise by reducing the noise generation from the orifice itself while reducing the noise by enhancing the effect of resonance muffling with the orifice having the smallest opening diameter.

The figure which shows the centrifugal blower of Embodiment 1 of this invention ((a) sectional side view, (b) top view) The perspective view which shows the orifice of Embodiment 1 of this invention ((a) Before opening diameter change, (b) After opening diameter change) The figure which shows the centrifugal blower of Embodiment 2 of this invention ((a) sectional side view, (b) top view) The figure which shows the centrifugal blower of Embodiment 3 of this invention ((a) sectional side view, (b) top view) The figure which shows the centrifugal blower of Embodiment 4 of this invention ((a) sectional side view, (b) top view) Sectional side view showing a conventional centrifugal blower

According to a first aspect of the present invention, there is provided an electric motor in which an impeller is connected to an outer frame having an opening so as to be rotatable about a rotation shaft, and a casing having a suction port surrounding the impeller. An orifice having an opening communicating with the opening of the outer frame, and a gap between a lower end of the casing and an end of the orifice, and the suction by the resonance space and the gap formed by the orifice A centrifugal blower that resonates and muffles noise emitted from the mouth. The centrifugal blower is characterized in that the opening diameter is changed to minimize the noise value in response to changes in noise emitted from the suction port . is intended, to changes in the noise generated color centrifugal blower, since it is changed to an optimum opening diameter, acts strongly silencing effect by the orifice against noise frequency characteristic is changed, the noise low An effect that can be.

  In addition, the centrifugal blower is characterized in that the opening has a bell mouth shape, and air can be smoothly guided to the casing, so that disturbance of the air flow is suppressed and noise can be reduced. Has the effect of being able to.

  In addition, it is a centrifugal blower characterized in that the opening diameter is automatically changed. Since the opening diameter is automatically changed even after the centrifugal blower is installed, the frequency characteristics of noise are always maintained. The combined opening diameter allows noise generated from the centrifugal blower to be reduced accurately due to the noise reduction effect of the orifice, while reducing the noise generation from the orifice itself, while reducing the noise generation from the orifice as much as possible. It has the effect | action that it can raise and noise can be reduced.

  Further, the present invention is a centrifugal blower characterized in that it has noise detecting means for measuring noise radiated from the opening, and the diameter of the opening is changed so as to minimize the measured noise value. An opening that minimizes noise generated by the orifice, which can reduce noise generated from the orifice itself due to an increase in air volume, and can also achieve a strong silencing effect by the orifice against noise whose frequency characteristics have changed. Since the diameter is changed, the noise can be reduced.

  In addition, the centrifugal blower is characterized in that it is provided with a rotational speed detection means for measuring the rotational speed of the impeller, and is changed to an opening diameter that exerts a strong silencing effect on the frequency of noise caused by the rotational speed. By changing the aperture diameter, the frequency at which the silencing effect due to the orifice acts strongly matches the frequency of the noise due to the rotation speed, thereby accurately reducing the noise due to the rotation speed by the orifice. And has an effect that noise can be reduced.

  Further, the orifice has an orifice outer wall extending in the direction of the rotation axis, and the outer wall is a centrifugal fan characterized by being a concentric cylinder with the opening, and the distance between the gap and the orifice outer wall is constant, A strong silencing effect acts on one frequency determined by the distance, and the noise can be reduced.

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

(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a centrifugal blower 1 used as a ceiling-embedded ventilation fan includes a multi-blade impeller 5 that is rotatable around a rotation shaft 4 in an outer shell 3 having an opening 2 on a lower surface. The casing 10 is provided with a casing 10 which surrounds the connected motor 6 and the impeller 5 and has a bell mouth-like suction port 7 in the opening and a discharge port 9 in the side wall 8. The casing 10 is a spiral scroll casing. The discharge port 9 of the casing 10 communicates with the discharge adapter 12 through a discharge opening 11 provided on one side surface of the outer shell 3. There is a flange portion 13 on the outer periphery of the lower surface of the outer shell 3, the outer shell 3 is fixed to the ceiling material 15 with screws or the like through a hole 14 provided in the flange portion 13, and an exhaust duct 16 arranged on the ceiling and communicating with the outside is provided. It is joined to the discharge port 9 via the discharge adapter 12.

  In addition, an orifice 18 that is concentric with the suction port 7 of the casing 10 and has a bell mouth-shaped opening 17 is disposed so as to close the opening 2 of the outer shell 3, and is surrounded by the casing 10, the orifice 18, and the outer shell 3. A space 19 is formed. Further, the end 20 of the orifice 18 is located at a gap dimension j from the lower surface of the casing 10 to form a gap 21.

  Details of the orifice 18 will be described with reference to FIG. As shown in FIG. 2, the orifice 18 has a movable part 22 including a bell mouth-shaped opening 17 divided into four equal parts in the circumferential direction. The movable part 22 includes an extension part 23 and is slid. As a result, the extension portion 23 is exposed so as to fill the space between the divided movable portions 22. The slide movement is performed according to the airflow value measured by the airflow detection means 24, for example, the airflow sensor, and the opening diameter Do is automatically changed from FIG. 2 (a) to FIG. 2 (b) by the slide movement distance. Is done. In addition, the slide movement itself is performed by dividing the movable part 22 into the diameter of the opening by the power unit 25 that is operated by a signal from the air volume detection unit 24, for example, a small motor and the moving mechanism unit 26 that is operated by the power unit 25. This is done by sliding in the direction.

  In the above configuration, when the impeller 5 is rotated by the electric motor 6, the intake air passes through the opening 17 of the orifice 18 from the main body opening 2, enters the impeller 5 through the suction port 7 of the casing 10, and is boosted by the impeller 5, It passes through the inside of the casing 10 and is discharged from the discharge adapter 12 to the exhaust duct 16 and discharged outside.

  Further, the rotation noise generated when the pressure is increased by the impeller 5, the turbulent flow noise caused by the vortex generated when passing through the inside of the casing 10, and the sound wave of the noise amplified by resonance in the casing 10 7, a part of the sound wave of the noise radiated from the suction port 7 of the casing 10 is passed from the gap portion 21 formed between the end 20 of the orifice 18 and the casing 10 to the resonance space 19. Incident. A part of the incident sound wave becomes an anti-phase sound wave due to reflection at the fixed end on the wall surface inside the resonance space 19 and returns to the gap portion 21, and resonance silence due to air column resonance that cancels a part of the sound wave emitted from the suction port 7 occurs. Therefore, noise can be reduced. Further, the closer the opening diameter Do is to the suction diameter Di, the higher the noise reduction effect due to resonance muffling.

  The exhaust duct 16 causes a pressure loss on the centrifugal blower 1 and determines the amount of air during operation. Therefore, the amount of air during operation varies depending on the construction state of the centrifugal blower 1.

  Moreover, the electric motor 6 can change an output arbitrarily, and can change the air volume of the centrifugal blower 1 arbitrarily. At this time, the opening diameter Do of the orifice 18 is changed simultaneously with the change of the output of the electric motor 6.

  At this time, the frequency characteristics of the noise radiated from the suction port 7 depend on the air volume determined by the pressure loss of the exhaust duct 16 and the frequency characteristics of the noise radiated from the suction port 7 change. Furthermore, when the air volume increases, a high wind speed wind comes into contact with the orifice 18 and the noise generated from the orifice 18 itself increases, resulting in a phenomenon such as being added to the radiated noise. Therefore, by changing the opening diameter Do according to the frequency characteristics of the noise by changing to the optimum opening diameter Do corresponding to the centrifugal blower 1, the noise emitted from the suction port 7 is silenced by the orifice 18. The effect can be reduced accurately, and the noise reduction effect can be enhanced with the orifice 18 having a small opening diameter Do as much as possible while reducing the noise generation from the orifice 18 itself. it can.

  Moreover, since the opening part 17 is bell mouth shape, the inflow of the air to the casing 10 can be smoothed and a noise can be reduced.

  In addition, since the opening diameter Do is automatically changed, the opening diameter Do is always changed to the opening diameter Do that works strongly even after construction, so that noise can be reduced.

  In addition, by changing the opening diameter Do according to the air volume measured by the air volume detection means 24, the noise reduction effect is strong because the opening diameter Do is changed to the optimum with respect to the noise change caused by the change in the air volume. Work and reduce noise.

  Further, since the opening diameter Do is changed to the optimum according to the change of the output of the electric motor 6, it is changed to the optimum opening diameter for the noise whose frequency characteristic changes due to the change of the output. The silencing effect works strongly and has the effect that noise can be reduced.

  In addition, since the casing 10 is a spiral scroll casing, the dynamic pressure of the air flowing out from the impeller 5 can be efficiently converted to static pressure and discharged from the discharge port 9, thereby reducing noise. it can.

(Embodiment 2)
The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. A second embodiment of the present invention will be described with reference to FIG. In the figure, the centrifugal blower 1 includes a noise detection means 27 such as a microphone, and the opening diameter Do is changed so that the noise value measured by the noise detection means 27 is minimized.

  At this time, the noise is reduced because the opening diameter Do is adjusted so that the noise reduction effect by the orifice 18 can be achieved while reducing the generation of noise from the orifice 18 itself.

(Embodiment 3)
The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Embodiment 3 of the present invention will be described with reference to FIG. In the drawing, the orifice 18 includes an orifice outer wall 28 extending in the axial direction of the impeller 5, and the orifice outer wall 28 is a cylinder concentric with the suction port 7. Further, the rotation speed detection means 29, for example, a tachometer is provided, and the opening diameter Do is changed by a signal from the rotation speed detection means 29. Further, the tongue portion 30 which is a part of the casing is located in the immediate vicinity of the blade of the impeller 5.

  In the above configuration, when the impeller 5 rotates and the wind is transported by the blade, the tongue portion 30 exists in the immediate vicinity of the blade, so that a sudden pressure fluctuation occurs, and the noise at the frequency due to the rotation speed increases. There is a case.

  At this time, when the opening diameter Do is changed by a signal from the rotational speed detection means 29, the frequency at which the silencing effect by the orifice 18 is increased and the frequency of the noise caused by the rotational speed of the impeller 5 are matched. Therefore, the noise reduction effect works strongly, so that noise can be reduced.

  Further, since the outer wall 28 of the orifice is a cylinder concentric with the suction port 7, the distance between the gap 21 and the outer wall 28 of the orifice is constant, so that the silencing effect with respect to a specific frequency is increased and noise can be reduced.

(Embodiment 4)
The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Embodiment 4 of the present invention will be described with reference to FIG. In the figure, the centrifugal blower 1 can change the opening diameter Do of the orifice, and when the centrifugal blower 1 is constructed, the opening diameter Do is changed so that the builder can set the opening diameter Do. A knob 31 is provided. Moreover, the mark 32 which showed the position of the knob 31 which can set the optimal opening part diameter Do with respect to the length of the exhaust duct 16 attached at the time of construction is provided.

  At this time, according to the length of the exhaust duct 16 attached at the time of construction of the centrifugal fan 1 by the installer, the knob 31 is changed to the position indicated by the mark 32, so that the optimum opening diameter Do is changed. Noise can be reduced.

  In the present invention, the opening diameter can be changed, and the optimal opening diameter can be set for the frequency characteristics of the noise generated from the suction port to enhance the effect of resonance silencing, and the increase in pressure loss due to the orifice is mitigated. In addition, the present invention provides a centrifugal blower that can enhance the effect of resonance muffling and reduce noise with an orifice having a small opening diameter as much as possible, and is particularly applicable to air conditioning equipment and ventilation blower equipment.

DESCRIPTION OF SYMBOLS 1 Centrifugal blower 2 Opening 3 Outer shell 4 Rotating shaft 5 Impeller 6 Electric motor 7 Suction port 8 Side wall 9 Discharge port 10 Casing 11 Discharge opening 12 Discharge adapter 13 Flange part 14 Hole 15 Ceiling material 16 Exhaust duct 17 Opening 18 Orifice 19 Resonance space DESCRIPTION OF SYMBOLS 20 End part 21 Gap part 22 Movable part 23 Extension part 24 Air volume detection means 25 Power part 26 Movement mechanism part 27 Noise detection means 28 Orifice outer wall 29 Rotation speed detection means 30 Tongue part 31 Knob 32 Mark Di Di suction port diameter Do opening diameter

Claims (6)

An electric motor in which an impeller is connected to an outer frame having an opening so as to be rotatable about a rotation shaft, a casing surrounding the impeller and having a suction port, and an opening communicating with the opening of the outer frame A centrifuge that has a gap between an orifice having a portion and a lower end of the casing and an end of the orifice, and that resonates and muffles noise emitted from the suction port by the resonance space and the gap formed by the orifice. A centrifugal blower characterized in that an opening diameter is changed so as to minimize a noise value with respect to a change in noise radiated from a suction port . The centrifugal blower according to claim 1, wherein the opening has a bell mouth shape. The centrifugal blower according to claim 1 or 2, wherein the opening diameter is automatically changed. The centrifuge according to any one of claims 1 to 3, further comprising a noise detecting means for measuring noise radiated from the opening, wherein the diameter of the opening is changed so as to minimize a measured noise value. Blower. A rotary speed detecting means for measuring the rotational speed of the impeller, with respect to the frequency of the noise caused by the rotational speed, one of claims 1-3, characterized in that to change the opening diameter acting strong silencing effect The centrifugal blower described in the crab. The centrifugal blower according to claim 5 , wherein the orifice includes an orifice outer wall extending in a rotation axis direction, and the orifice outer wall is a cylindrical wall concentric with the opening.

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