CN107975497B

CN107975497B - Centrifugal fan spiral case

Info

Publication number: CN107975497B
Application number: CN201710369371.0A
Authority: CN
Inventors: 何立博; 茅忠群; 诸永定; 申志贤
Original assignee: Ningbo Fotile Kitchen Ware Co Ltd
Current assignee: Ningbo Fotile Kitchen Ware Co Ltd
Priority date: 2017-05-23
Filing date: 2017-05-23
Publication date: 2024-04-02
Anticipated expiration: 2037-05-23
Also published as: CN107975497A

Abstract

The utility model provides a centrifugal fan spiral case, its spiral case molded lines is the helix including the initial line AC that is located molded lines one end and the end line MN that is located the molded lines other end, spiral case molded lines between initial line AC and the end line MN, its characterized in that: the spiral line comprises a first spiral line CD connected with the initial line AC and a second spiral line DM connected with the final line MN, wherein the first spiral line CD is an equiangular spiral line, and the second spiral line DM is an angle-variable spiral line with a tapered expansion angle. The invention has the advantages that: according to the volute molded line of the centrifugal fan, the first spiral line CD between the initial line AC and the end line MN is designed into an equiangular spiral line, the second spiral line DM is an angle-variable spiral line with a tapered expansion angle, so that the left and right sizes of the volute are reduced, the smoothness of air flow collection and passing in the volute is improved, the static pressure of the maximum static pressure and an effective air volume section is obviously improved, the effect of a large volute is achieved under the small size, pneumatic noise is reduced, and user experience is improved.

Description

Centrifugal fan spiral case

Technical Field

The invention relates to a fan, in particular to a centrifugal fan volute.

Background

Centrifugal fans are widely used in range hoods due to their advantages of large suction force, low noise, compact structure, and the like. The volute is one of the core components of the centrifugal fan, and serves to concentrate the gas leaving the impeller, guide the gas out to the outlet of the volute, and convert dynamic pressure into static pressure. The volute structure of the existing centrifugal fan comprises a volute top plate, a volute bottom plate and a volute coaming connected with the volute top plate and the volute bottom plate, wherein the volute top plate and the volute bottom plate are identical in other molded lines except for volute tongue positions. Conventional volute designs are generally based on a unitary theory, and there are two assumptions that the flow parameters are uniformly distributed around the inlet circumference and the moment of airflow in the volute is unchanged, and the volute line designed according to a unitary theory is generally an equiangular spiral. However, in practice, due to the non-axisymmetric shape of the volute, particularly the influence of the volute tongue, a non-uniform pressure field is formed at the impeller outlet, which inevitably results in non-uniform flow field at the impeller outlet, i.e. at the volute inlet. The non-uniformity of inlet circumferential flow parameters and the influence of a flow field in a volute circumferential plane are not considered in the unitary theory, so that the volute designed according to the theory has poor performance, and particularly in a high back pressure working state, the volute is obviously deteriorated, and in addition, the left and right sizes of the volute are generally larger, so that the overall size of a product is influenced.

The prior art also discloses various volute structures of centrifugal fans, such as a centrifugal fan for a range hood and a volute molded line generating method thereof disclosed in Chinese patent publication No. ZL 201110118687.5 (issued publication No. CN 102182707B), wherein the volute comprises a volute top plate, a volute bottom plate and a volute coaming, the contour line of the inner side molded surface of the volute coaming is a volute molded line, and the volute molded line is formed by smoothly transiting and connecting a first straight line DE, a first circular arc EF, a second circular arc FG, a spiral GH and a second straight line HI, and although the volute is favorable for improving the air quantity, the air pressure and the efficiency of the centrifugal fan and reducing the pneumatic noise after adopting the volute molded line, the volute structure still does not fully consider the influence of the non-uniformity of the inlet circumferential flow parameters and the flow field in the volute circumferential plane, and needs to be further improved

Disclosure of Invention

The invention aims to solve the technical problem of providing a centrifugal fan volute which can reduce the left and right sizes of the volute and can improve the maximum static pressure and the effective air volume section.

The technical scheme adopted for solving the technical problems is as follows: this centrifugal fan spiral case, the spiral case molded lines of this spiral case include the initial line AC that is located molded lines one end and the end line MN that is located the molded lines other end, initial line AC is including the straight line AB that is adjacent the fan air outlet and the curve BC that corresponds to the volute tongue position, end line MN is adjacent the fan air outlet, the spiral case molded lines between initial line AC and the end line MN are the helix, its characterized in that: the spiral line comprises a first spiral line CD connected with a starting line AC and a second spiral line DM connected with an ending line MN, wherein the first spiral line CD is an equiangular spiral line with a constant expansion angle, and the second spiral line DM is an angle-variable spiral line with a tapered expansion angle.

Preferably, the polar radius R of the first spiral CD _CD The definition is as follows:wherein R is ₂ Is the outer diameter of the impeller, t is the designed clearance between the outer circumference of the impeller and the top end of the volute tongue, and t/R ₂ ∈[0.01,0.15]Expansion angle alpha epsilon [3 DEG, 8 DEG ]]，θ ₀ Is set for a selected initial angle, and θ ₀ ∈[60°，180°]θ is the polar angular variable at any point on the first spiral CD.

Further preferably, the polar radius R of the second spiral DM _DM The definition is as follows:wherein R is ₂ Is the outer diameter of the impeller, t is the designed clearance between the outer circumference of the impeller and the top end of the volute tongue, and t/R ₂ ∈[0.01,0.15]Variable divergence angle->α ₁ ∈[3°,8°],α ₂ ∈[3°,8°]And alpha is ₁ ≥α ₂ ，The adjustment item s E [ -0.5,0.5]，r∈[-5，5]And r is not equal to 1, θ is the polar coordinate angular variable of any point on the second spiral DM, α ₁ Is the expansion angle alpha of the point D ₂ Is the expansion angle of M point +.>Is the wrap angle of the second spiral DM.

Further preferably, the ending line MN includes a straight line segment adjacent to the air outlet and a curved line segment adjacent to the DM.

Compared with the prior art, the invention has the advantages that: the volute inlet circumferential non-uniformity is considered during design of the volute molded line of the centrifugal fan, the volute molded line between the starting line AC and the ending line MN is designed into a first spiral line CD and a second spiral line DM, the first spiral line CD is an equiangular spiral line, the second spiral line DM is an angle-variable spiral line with a tapered expansion angle, the left and right sizes of the volute are reduced, the smoothness of air flow collection and passing in the volute is improved, the static pressure of the maximum static pressure and the static pressure of an effective air volume section are obviously improved, the large volute effect is achieved under the small size, pneumatic noise is reduced, and user experience is improved.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the embodiments of the drawings.

As shown in fig. 1, the volute molded line of the centrifugal fan volute in this embodiment includes a start line AC located at one end of the molded line and an end line MN located at the other end of the molded line, where the start line AC includes a straight line AB adjacent to the fan air outlet and a curve BC corresponding to the volute tongue portion, and the end line MN is adjacent to the fan air outlet.

The spiral line between the starting line AC and the ending line MN is a spiral line, the spiral line comprises a first spiral line CD connected with the starting line AC and a second spiral line DM connected with the ending line MN, the first spiral line CD is an equiangular spiral line with a constant expansion angle, and the second spiral line DM is an angle-variable spiral line with a tapered expansion angle. In addition, the ending line MN includes a straight line segment adjacent to the air outlet and a curved line segment adjacent to DM.

In this embodiment, the pole radius R of the first spiral CD _CD The definition is as follows:wherein R is ₂ Is the outer diameter of the impeller, t is the designed clearance between the outer circumference of the impeller and the top end of the volute tongue, and t/R ₂ ∈[0.01,0.15]Expansion angle alpha epsilon [3 DEG, 8 DEG ]]，θ ₀ Is set for a selected initial angle, and θ ₀ ∈[60°，180°]θ is the polar angular variable at any point on the first spiral CD.

In the present embodiment, the polar radius R of the second spiral DM _DM The definition is as follows:wherein R is ₂ Is the outer diameter of the impeller, t is the designed clearance between the outer circumference of the impeller and the top end of the volute tongue, and t/R ₂ ∈[0.01,0.15]Variable divergence angleα ₁ ∈[3°,8°],α ₂ ∈[3°,8°]And alpha is ₁ ≥α ₂ ，The adjustment item s E [ -0.5,0.5]，r∈[-5，5]And r is not equal to 1, θ is the polar coordinate angular variable of any point on the second spiral DM, α ₁ Is the expansion angle alpha of the point D ₂ Is the expansion angle of M point +.>Is the wrap angle of the second spiral DM. Taking the expansion angle of the point D in FIG. 1 as an example, the following is that L1 is perpendicular to OD, L2 is tangential to the first spiral CD, and the included angle alpha between L1 and L2 ₁ The expansion angle of the volute molded line at the point D is obtained.

The volute molded lines design time of this centrifugal fan spiral case has considered the spiral case circumference non-uniformity that admits air, through the spiral case molded lines design into first spiral line CD and second spiral line DM between the line AC of beginning and the line MN of ending, and first spiral line CD is equiangular spiral line, second spiral line DM is the variable angle spiral line that the expansion angle was gradually reduced, make the left and right sides size of spiral case narrow, improved the inside air current of spiral case and collected and the smoothness degree of passing through, great promotion biggest static pressure and the static pressure of effective amount of wind section, realized reaching big spiral case effect under the small-size, pneumatic noise has been reduced simultaneously, user experience has been promoted.

The foregoing is merely illustrative of the preferred embodiments of this invention, and it will be appreciated by those skilled in the art that variations and modifications of this invention can be made without departing from the principles of the invention, and these are considered to be within the scope of the invention.

Claims

1. The utility model provides a centrifugal fan spiral case, the spiral case molded lines of this spiral case include the initial line AC that is located molded lines one end and the end line MN that is located the molded lines other end, initial line AC is including the straight line AB that is adjacent the fan air outlet and the curve BC that corresponds to the volute tongue position, end line MN is adjacent the fan air outlet, the spiral case molded lines between initial line AC and the end line MN are the helix, its characterized in that: the spiral line comprises a first spiral line CD connected with a starting line AC and a second spiral line DM connected with an ending line MN, wherein the first spiral line CD is an equiangular spiral line with a constant expansion angle, and the second spiral line DM is an angle-variable spiral line with a tapered expansion angle;

the polar radius R of the first spiral line CD _CD The definition is as follows:wherein R is ₂ Is the outer diameter of the impeller, t is the designed clearance between the outer circumference of the impeller and the top end of the volute tongue, and t/R ₂ ∈[0.01,0.15]Expansion angle alpha epsilon [3 DEG, 8 DEG ]]，θ ₀ Is the starting angle of the D point of the first spiral line CD, and θ ₀ ∈[60°，180°]θ is the polar angular variable of any point on the first spiral CD;

polar radius R of the second spiral DM _DM The definition is as follows:wherein R is ₂ Is the outer diameter of the impeller, t is the designed clearance between the outer circumference of the impeller and the top end of the volute tongue, and t/R ₂ ∈[0.01,0.15]Variable divergence angleα ₁ ∈[3°,8°],α2∈[3°,8°]And alpha is ₁ ≥α ₂ ，The adjustment item s E [ -0.5,0.5]，r∈[-5，5]And r is not equal to 1, θ is the polar coordinate angular variable of any point on the second spiral DM, α ₁ Is the expansion angle alpha of the point D ₂ Is the expansion angle of M point +.>Is the wrap angle of the second spiral DM.

2. The centrifugal fan volute of claim 1, wherein: the ending line MN includes a straight line segment adjacent to the air outlet and a curved line segment adjacent to the DM.