A volute structure of a centrifugal fan

Abstract

The present invention relates to a volute structure of a centrifugal fan, including a volute tongue with a volute tongue inner wall, the two sides of the volute tongue are closed to form a cavity, a first baffle is arranged on the outer side of the volute tongue and extends into the cavity along the volute tongue outer wall, a narrow and long guide channel is formed between the upper part of the first baffle and the volute tongue inner wall, a guide cavity is enclosed between the lower part of the first baffle and the inner wall of the cavity, an opening for air flow to enter the guide cavity is opened at the bottom of the volute tongue inner wall, and a guide block capable of covering or opening the opening is also arranged in the guide cavity. When the fan flow rate is small, the noise is small, and the guide block can close the opening; when the fan flow rate is large, the gas backflow at the volute tongue increases, the guide block opens the opening, part of the gas enters the guide cavity through the opening and is further accelerated through the narrow and long guide channel and then discharged from the air outlet, realizing the secondary discharge of the reflux gas, reducing the gas backflow, breaking the vortex problem, thereby reducing the fan noise and improving the fan efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of range hoods, and in particular to a volute structure of a centrifugal fan. Background Art

[0002] Household range hoods use multi-blade centrifugal fans for air intake and exhaust. The fan is generally composed of a volute, a motor, an impeller, etc. The tongue-shaped protrusion in the volute is called the volute tongue, and its main function is to separate the flowing gas and prevent the gas from circulating in the volute. Due to the high gas pressure and complex flow near the volute tongue, the flow noise and rotation noise generated near the volute tongue are the main noise sources of the centrifugal fan. Reducing the noise near the volute tongue can significantly reduce the noise of the range hood.

[0003] The Chinese patent application "A fan volute for a range hood" (application number: CN201610111243.1) with application publication number CN105526193A discloses a structure, which includes a volute tongue, which includes a volute tongue inner wall, and the volute tongue forms a closed cavity, in which at least one longitudinal partition is arranged along the axial direction of the volute, and a plurality of radial partitions are arranged along the axial direction perpendicular to the volute, and the longitudinal partition and the radial partition divide the cavity into a plurality of independent closed silencing cavities, and a hole is opened on the inner wall portion of the volute tongue corresponding to each silencing cavity. The above structure divides the cavity in the volute tongue into a plurality of independent closed small cavities, and the small cavities and the corresponding holes opened on the side walls form a Helmholtz resonator. According to the Helmholtz resonance principle, after the sound propagates, the sound wave close to the natural frequency of the resonator resonates with the resonator, and during the vibration process, the air column in the cavity rubs against the inner wall of the cavity to consume sound energy, thereby absorbing and reducing noise.

[0004] The above structure reduces the fan noise to a certain extent by setting up a silencer cavity. However, due to the small space at the volute tongue, the gas is difficult to be discharged at one time, and the residual gas is easy to flow back and form vortices, resulting in reduced fan efficiency and vortex noise, which in turn causes the fan to still have a large noise. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a volute structure of a centrifugal fan which can effectively break vortex and reduce gas backflow, thereby reducing fan noise and improving fan efficiency in view of the current status of the prior art.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a volute structure of a centrifugal fan, including a volute tongue, the volute tongue having a volute tongue inner wall, characterized in that: both sides of the volute tongue are closed to form a cavity, a first baffle is provided on the outer side of the volute tongue extending into the cavity along the volute tongue outer wall, a narrow and long guide channel is formed between the upper part of the first baffle and the corresponding volute tongue inner wall, a guide cavity is enclosed between the lower part of the first baffle and the cavity inner wall, an opening for air flow to enter the guide cavity is opened on the volute tongue inner wall at a position corresponding to the bottom of the guide cavity, and a guide block capable of covering or opening the opening is also provided in the guide cavity.

[0007] As an improvement, the volute tongue is provided with an adjustment component that can adjust the opening and closing of the guide block relative to the opening according to the size of the wind volume. With this structure, when the wind volume is small, the adjustment component does not work, and the conventional structure of the volute tongue meets the demand. When the wind volume is large, the adjustment component drives the guide block to move under the impact of the wind flow, thereby opening the opening and playing the role of breaking the vortex and reducing gas reflux.

[0008] Preferably, the adjustment assembly includes a connecting arm, a pin and an elastic member, wherein the connecting arm is arranged at the first end of the guide block and is rotatably connected to the side wall of the volute tongue through the pin, the guide block is rotatably arranged above the opening and can float upward under the impact of wind flow to open the opening, the second end of the guide block is a rotating free end, and the elastic member enables the guide block to always maintain the tendency to cover the opening. The elastic coefficient of the elastic member can be set according to the specific performance parameters of the fan system such as wind pressure and flow, so as to adjust the closing of the opening according to the size of the wind volume and keep the fan low noise.

[0009] In order to facilitate assembly, the elastic member is a spring, the first end of which abuts against the upper surface of the connecting arm, and the second end of which abuts against the inner wall of the volute tongue above it. Preferably, a plane perpendicular to the axial arrangement of the spring is formed on the inner wall of the volute tongue above the elastic member, and the second end of the spring abuts against the plane; and a slot is provided on the upper surface of the connecting arm for the first end of the spring to be clamped therein.

[0010] As a further improvement, a second baffle is provided on the outside of the first baffle, and the second baffle, the side wall of the volute tongue and the first baffle together enclose a closed first cavity, and a first through hole is provided on the first baffle for airflow to enter the first cavity from the guide cavity. Preferably, the thickness of the first baffle is 1.5 to 2 mm, and the diameter of the first through hole is 1 to 1.8 mm. With such a structure, the secondary removal of the reflux gas can be achieved, and the eddy current can be further reduced. At the same time, the first baffle, the second baffle and the first cavity between the two can form a sound-absorbing resonance structure, thereby suppressing the turbulent noise there and achieving a noise reduction effect.

[0011] Further improvement, a third baffle arranged parallel to the second baffle is provided in the first cavity, and the third baffle, the second baffle and the inner wall of the volute tongue together enclose the second cavity, and the third baffle is provided with a second through hole for airflow from the first cavity into the second cavity. The thickness of the third baffle is 0.75-1 mm, and the diameter of the second through hole is 0.5-0.75 mm. Although the first baffle, the second baffle and the first cavity between the two form a sound-absorbing resonance structure, they may also generate nonlinear acoustic resistance, thereby forming secondary noise. The third baffle and the second cavity are provided to suppress a wider noise band, better offset the original noise, and have a higher sound absorption coefficient, ultimately achieving the reduction of noise at the volute tongue under large flow conditions, the elimination of vortices, and the improvement of the total pressure and efficiency of the fan.

[0012] In the above-mentioned schemes, the volute also includes a volute ring wall, the volute tongue is connected to the first end of the volute ring wall, the inner wall of the volute tongue includes a first arc surface segment, a second arc surface segment and a first plane segment, the first arc surface segment is arranged close to the impeller of the centrifugal fan and its lower surface constitutes a first guide surface of the centrifugal fan, the first plane segment is arranged on the air outlet side of the volute and its inner surface constitutes a second guide surface of the centrifugal fan, and the second arc surface segment is connected between the first arc surface segment and the first plane segment.

[0013] To facilitate connection, the volute also includes a front cover plate and a rear cover plate, the volute annular wall is connected between the front cover plate and the rear cover plate, the upper edge of the volute tongue is connected to the upper edges of the front cover plate and the rear cover plate, and the lower edge of the volute tongue is connected to the first end edge of the volute annular wall and is sealed by silicone.

[0014] Preferably, the first baffle includes a second plane segment and a third arc segment, the second plane segment is arranged close to the first plane segment, the upper end of the third arc segment is connected with the lower end of the second plane segment, the third arc segment is arched toward the second arc segment and the lower end is connected with the upper surface of the first arc segment. The width of the guide channel formed between the first plane segment and the second plane segment gradually decreases from bottom to top. The above structure enables the guide cavity and the narrow and long guide channel to form a structure roughly in the shape of 6, thereby playing a good role in guiding and breaking vortices.

[0015] Preferably, the lower surface of the guide block is formed as a first curved surface that arches downward, and correspondingly, the two side walls of the opening are formed as matching surfaces that can match the first curved surface. The upper surface of the guide block is formed with a second curved surface that arches upward, the curvature of the second curved surface is greater than the curvature of the first curved surface, and the connection between the first curved surface and the second curved surface is smoothly transitioned. The above structure can reduce the resistance of the guide block to the wind flow.

[0016] Compared with the prior art, the advantages of the present invention are: the present invention closes both sides of the volute tongue and arranges a first baffle inside the volute tongue. During the use of the centrifugal fan, when the fan flow is small, the noise is small, and the guide block can close the opening; when the fan flow is large, the reflux of gas at the volute tongue increases, and the opening is opened by the guide block. Part of the gas enters the guide cavity through the opening and is further accelerated through the narrow and long guide channel and then discharged from the air outlet, thereby realizing the secondary discharge of the reflux gas, reducing the gas reflux, and eliminating the vortex problem, thereby reducing the fan noise and improving the fan efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of an embodiment of the present invention (equipped with an impeller);

[0018] Figure 2 for Figure 1 A cross-sectional view of

[0019] Figure 3 It is a schematic diagram of the structure of the snail tongue in an embodiment of the present invention;

[0020] Figure 4 It is a schematic diagram of the assembly structure of the guide block, the connecting arm and the elastic member in an embodiment of the present invention;

[0021] Figure 5 is a cross-sectional view of a snail tongue in an embodiment of the present invention;

[0022] Figure 6 for Figure 5 Schematic diagram of the structure of the hidden guide block. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings.

[0024] like Figures 1 to 6 As shown, the volute structure of the centrifugal fan of this embodiment includes a volute tongue 1, a front cover plate 2, a rear cover plate 3 and a volute ring wall 4. The front cover plate 2 and the rear cover plate 3 are arranged in a front-to-back spacing, and the volute ring wall 4 is connected between the front cover plate 2 and the rear cover plate 3. The volute tongue 1 is arranged on the first end of the volute ring wall 4, and a side wall of the volute tongue 1 and the side wall opposite to the volute ring wall 4 and the front cover plate 2 and the rear cover plate 3 together enclose an air outlet 40.

[0025] The volute tongue 1 of this embodiment has a volute tongue inner wall 11, which includes a first arc surface segment 111, a second arc surface segment 112 and a first plane segment 113. The first arc surface segment 111 is arranged close to the impeller of the centrifugal fan and its lower surface constitutes the first guide surface of the centrifugal fan. The first plane segment 113 is arranged on the air outlet 40 side of the volute and its inner surface constitutes the second guide surface of the centrifugal fan. The second arc surface segment 112 is connected between the first arc surface segment 111 and the first plane segment 113. The upper edge of the volute tongue 1 of this embodiment is connected to the upper edges of the front cover plate 2 and the rear cover plate 3 by screws, and the lower edge of the volute tongue 1 is connected to the first end edge of the volute ring wall 4 by screw connection and sealed by silicone.

[0026] In this embodiment, a volute tongue side plate 12 is respectively provided on both sides of the volute tongue 1, and the volute tongue side plate 12 closes both sides of the volute tongue 1 to form a cavity 10. A first baffle 13 extending along the outer wall of the volute tongue into the cavity 10 is provided on the outer side of the volute tongue 1 corresponding to the opening of the cavity 10. The first baffle 13 includes a second plane section 131 and a third arc surface section 132. The second plane section 131 is arranged close to the first plane section 113, and the upper end of the third arc surface section 132 is connected with the lower end of the second plane section 131. The third arc surface section 132 is arched toward the second arc surface section 112 and the lower end is connected with the upper surface of the first arc surface section 112. A narrow and long guide channel 14 is formed between the second plane section 131 of the first baffle 13 and the first plane section 11 of the inner wall 11 of the volute tongue, and the width of the guide channel 14 gradually decreases from bottom to top. The lower part of the first baffle 13 and the inner wall of the cavity 10 enclose a guide cavity 15, and an opening 1111 for airflow to enter the guide cavity 15 is opened on the first arc surface segment 111, and a guide block 100 is also provided in the guide cavity 15 to cover or open the opening 1111. The lower surface of the guide block 100 is formed as a first arc surface 101 that arches downward, and correspondingly, the two side walls of the opening 1111 are formed as matching surfaces 1112 that can match the first arc surface 101. The upper surface of the guide block 100 is formed with a second arc surface 102 that arches upward, and the curvature of the second arc surface 102 is greater than that of the first arc surface 101, and the connection between the first arc surface 101 and the second arc surface 102 is smoothly transitioned, and this structure can reduce the resistance of the guide block 100 to the wind flow. The guide cavity 15 of this embodiment and the narrow and long guide channel 14 together form a structure roughly in the shape of 6, thereby playing a good role in guiding and breaking vortices.

[0027] The volute tongue 1 is provided with an adjustment component 16 that can adjust the opening and closing of the guide block 100 relative to the opening 1111 according to the size of the wind volume. The adjustment component 16 includes a connecting arm 161, a pin 162 and an elastic member 163. The connecting arm 161 is two and is respectively connected to the two sides of the first end of the guide block 100. The other end of the connecting arm 161 is rotatably connected to the volute tongue side plate 12 through the pin 162, and the connection is arranged near the second arc surface section 112. The guide block 100 is rotatably arranged above the opening 1111 and can float upward under the impact of the wind flow to open the opening 1111. The second end of the guide block 100 is a rotating free end, and the elastic member 163 makes the guide block 100 always keep the tendency of covering the opening 1111. The elastic coefficient of the elastic member 163 can be set according to the specific performance parameters of the fan system such as the wind pressure and flow rate, so as to adjust the closing of the opening according to the size of the wind volume and keep the fan low noise. The elastic member 163 of this embodiment is a spring, the first end of which abuts against the upper surface of the connecting arm 161, and the second end of which abuts against the inner wall of the volute tongue above it. A plane 114 arranged perpendicular to the axial direction of the spring is formed on the inner wall of the volute tongue above the elastic member 163, and the second end of the spring abuts against the plane 114. A slot 1611 is provided on the upper surface of the connecting arm 161 for the first end of the spring to be clamped therein.

[0028] In this embodiment, a second baffle 17 is arranged outside the first baffle 13, the upper end of the second baffle 17 is connected to the air outlet end of the first plane section 113, and the lower end of the second baffle 17 is connected to the outer end of the first plane section 113, so as to enclose a closed first cavity 170 together with the volute tongue side plate 12 and the first baffle 13, and a first through hole 130 is opened on the first baffle 13 for airflow from the guide cavity 15 into the first cavity 170. The thickness of the first baffle 13 is 1.5 to 2 mm, and the diameter of the first through hole 130 is 1 to 1.8 mm. A third baffle 18 arranged parallel to the second baffle 17 is arranged in the first cavity 170, and the third baffle 18, the second baffle 17, and the inner wall of the volute tongue together enclose a second cavity 180, and a second through hole 181 is opened on the third baffle 18 for airflow from the first cavity 17 into the second cavity 18. The thickness of the third baffle 18 is 0.75-1 mm, and the diameter of the second through hole 181 is 0.5-0.75 mm. Although the first baffle 13, the second baffle 17 and the first cavity 170 therebetween form a sound-absorbing resonance structure, they may also generate nonlinear acoustic resistance, thereby forming secondary noise. The third baffle 18 and the second cavity 180 can suppress a wider noise band, better offset the original noise, and have a higher sound absorption coefficient, ultimately achieving the reduction of noise at the volute tongue under large flow conditions, the elimination of vortices, and the improvement of the fan's total pressure and efficiency.

[0029] When the volute structure of the present embodiment is used, when the fan flow is small, the noise is small, and the guide block 100 closes the opening 1111; when the fan flow is large, the gas backflow at the volute tongue 1 increases, and the airflow impacts the guide block 100 to overcome the elastic force of the elastic member 163 and float upward, opening the opening 1111. At this time, part of the gas enters the guide cavity 15 through the opening 1111, and part of the gas entering the guide cavity 15 is directly accelerated through the narrow and long guide channel 14 and discharged from the air outlet 40, and the other part passes through the first through hole 130 on the first baffle 13 and enters the first cavity 17. 0, and then passes through the second through hole 181 on the third baffle 18 into the second cavity 180 and is discharged from the guide channel 14 after circulation, thereby realizing the secondary discharge of the reflux gas, reducing the gas reflux, and eliminating the vortex problem, thereby reducing the fan noise and improving the fan efficiency; and the sound-absorbing resonance structure formed by the first baffle, the second baffle, and the third baffle can suppress turbulent noise, suppress a wider noise frequency band, better offset the original noise, and have a higher sound absorption coefficient, ultimately achieving the reduction of noise at the volute tongue under large flow conditions, the elimination of vortices, and the improvement of the total pressure and efficiency of the fan.

Claims

1. A volute structure of a centrifugal fan, comprising a volute tongue (1), wherein the volute tongue (1) has a volute tongue inner wall (11), characterized in that: The two sides of the volute tongue (1) are closed to form a cavity (10); a first baffle (13) is provided on the outer side of the volute tongue (1) and extends into the cavity (10) along the outer wall of the volute tongue (1); a narrow and long guide channel (14) is formed between the upper part of the first baffle (13) and the corresponding volute tongue inner wall (11); a guide cavity (15) is enclosed between the lower part of the first baffle (13) and the inner wall of the cavity (10); an opening (1111) for airflow to enter the guide cavity (15) is provided on the volute tongue inner wall (11) at a position corresponding to the bottom of the guide cavity (15); and a guide block (100) capable of covering or opening the opening (1111) is also provided in the guide cavity (15); The volute tongue (1) is provided with an adjustment component (16) capable of adjusting whether the guide block (100) is opened or closed relative to the opening (1111) according to the amount of air flow; a second baffle (17) is provided on the outer side of the first baffle (13); the second baffle (17) and the volute tongue side wall and the first baffle (13) together enclose a closed first cavity (170); the first baffle (13) is provided with a first through hole (130) for allowing air to enter the first cavity (170) from the guide cavity (15); a third baffle (18) is provided in the first cavity (170) and is arranged parallel to the second baffle (17); the third baffle (18) and the second baffle (17) and the volute tongue inner wall together enclose a second cavity (180); the third baffle (18) is provided with a second through hole (181) for allowing air to enter the second cavity (180) from the first cavity (170).

2. The volute structure of the centrifugal fan according to claim 1, characterized in that: The adjustment assembly (16) comprises a connecting arm (161), a pin shaft (162) and an elastic member (163); the connecting arm (161) is arranged at the first end of the guide block (100) and is rotatably connected to the side wall of the volute tongue through the pin shaft (162); the guide block (100) is rotatably arranged above the opening (1111) and can float upward under the impact of wind flow to open the opening (1111); the second end of the guide block (100) is a rotating free end; and the elastic member (163) enables the guide block (100) to always maintain a tendency to cover the opening (1111).

3. The volute structure of the centrifugal fan according to claim 2, characterized in that: The elastic member (163) is a spring, the first end of which abuts against the upper surface of the connecting arm (161), and the second end of which abuts against the inner wall of the volute tongue above it.

4. The volute structure of the centrifugal fan according to claim 3, characterized in that: A plane (114) arranged perpendicular to the axial direction of the spring is formed on the inner wall of the volute tongue above the elastic member (163), and the second end of the spring abuts against the plane (114); a slot (1611) for the first end of the spring to be clamped therein is formed on the upper surface of the connecting arm (161).

5. The volute structure of the centrifugal fan according to claim 1, characterized in that: The thickness of the first baffle (13) is 1.5 to 2 mm, and the diameter of the first through hole (130) is 1 to 1.8 mm.

6. The volute structure of the centrifugal fan according to claim 1, characterized in that: The thickness of the third baffle (18) is 0.75 to 1 mm, and the diameter of the second through hole (181) is 0.5 to 0.75 mm.

7. The volute structure of a centrifugal fan according to any one of claims 1 to 6, characterized in that: The volute structure of the centrifugal fan also includes a volute ring wall (4), the volute tongue (1) is connected to the first end of the volute ring wall (4), the volute tongue inner wall (11) includes a first arc surface segment (111), a second arc surface segment (112) and a first plane segment (113), the first arc surface segment (111) is arranged close to the impeller of the centrifugal fan and its lower surface constitutes a first guide surface of the centrifugal fan, the first plane segment (113) is arranged on the air outlet (40) side of the volute and its inner surface constitutes a second guide surface of the centrifugal fan, and the second arc surface segment (112) is connected between the first arc surface segment (111) and the first plane segment (113).

8. The volute structure of the centrifugal fan according to claim 7, characterized in that: The volute structure of the centrifugal fan further comprises a front cover plate (2) and a rear cover plate (3); the volute annular wall (4) is connected between the front cover plate (2) and the rear cover plate (3); the upper edge of the volute tongue (1) is connected to the upper edges of the front cover plate (2) and the rear cover plate (3); the lower edge of the volute tongue (1) is connected to the first end edge of the volute annular wall (4) and is sealed by silicone.

9. The volute structure of the centrifugal fan according to claim 7, characterized in that: The first baffle (13) comprises a second plane section (131) and a third arc surface section (132); the second plane section (131) is arranged close to the first plane section (113); the upper end of the third arc surface section (132) is connected to the lower end of the second plane section (131); the third arc surface section (132) is arched toward the second arc surface section (112) and the lower end is connected to the upper surface of the first arc surface section (111).

10. The volute structure of the centrifugal fan according to claim 9, characterized in that: The width of the guide channel (14) formed between the first plane section (113) and the second plane section (131) gradually decreases from bottom to top.

11. The volute structure of a centrifugal fan according to claim 1, characterized in that: The lower surface of the guide block (100) is formed as a first curved surface (101) that arches downward, and correspondingly, the two side walls of the opening (1111) are formed as matching surfaces (1112) that can match the first curved surface (101).

12. The volute structure of the centrifugal fan according to claim 11, characterized in that: The upper surface of the guide block (100) is formed with a second curved surface (102) that arches upwards, the curvature of the second curved surface (102) is greater than the curvature of the first curved surface (101), and the connection between the first curved surface (101) and the second curved surface (102) is smoothly transitioned.

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