Sanitary pump impeller and method of designing the same

Abstract

The application provides a sanitary pump impeller and a design method thereof. The impeller comprises a central impeller inlet edge and a circumferential impeller outlet edge, and a plurality of blades and balance holes are uniformly distributed around the impeller inlet edge. The design method comprises the following seven steps: determining basic design parameters of the impeller, setting blade inlet installation angle, outlet installation angle and wrap angle, determining blade working surface inlet and outlet positions, obtaining a blade profile control point, drawing a blade working surface profile, determining blade thickness, drawing a blade back surface profile, adjusting blade inlet and outlet geometrical shapes, completing blade design, determining balance hole number, diameter and position, completing balance hole design, determining blade tip clearance size, and completing semi-open impeller design. The application can reduce fluid leakage in the pump, improve hydraulic efficiency of the whole pump, and balance axial force of the impeller.

Description

Technical Field

[0001] This invention relates to the field of pump design, specifically to a sanitary pump impeller and its design method. Background Technology

[0002] Sanitary pumps are classified according to their application, and are widely used for conveying various liquid materials, such as in the dairy, beer, and beverage production industries. Centrifugal sanitary pumps have the widest range of applications; they utilize the centrifugal principle to accelerate the conveyed medium within the blade channels through rotating blades.

[0003] In existing technologies, centrifugal pumps mostly use closed impellers. However, closed-impeller centrifugal pumps are prone to clogging when conveying high-viscosity liquids, affecting their normal operation and making disassembly inconvenient for maintenance or replacement. Therefore, in the food industry, sanitary pumps often use semi-open impellers for easier cleaning. However, because there is a certain tip clearance between the impeller and the pump casing, fluid leakage is likely to occur in these sanitary pumps, leading to lower efficiency. Furthermore, the semi-open impeller generates greater axial force. Summary of the Invention

[0004] In order to solve the problems of the prior art, the present invention provides a sanitary pump impeller and its design method, which can reduce fluid leakage inside the pump, improve the hydraulic efficiency of the whole pump, and balance the axial force of the impeller.

[0005] This invention provides a sanitary pump impeller, including an impeller inlet edge located in the center and an impeller outlet edge surrounding the perimeter. A plurality of blades and balancing holes are evenly distributed around the impeller inlet edge. The blades are non-uniform thickness cylindrical blades, including a blade inlet edge, a blade working surface, a blade back surface, and a blade outlet edge. The blade inlet edge is close to the impeller inlet edge, and the thickness of the blade gradually increases from the blade inlet edge to the blade outlet edge. The blade outlet edge partially overlaps with the impeller outlet edge.

[0006] In a further improvement, the blade inlet edge and blade outlet edge are circular, and the blade is smoothly tangent to the blade working surface and back surface.

[0007] In a further improvement, the blade tip clearance is a uniform and equal clearance that remains constant from the impeller inlet side to the outlet side.

[0008] The present invention also provides a design method for a sanitary pump impeller, comprising the following steps:

[0009] Step 1: Determine the basic design parameters of the impeller, including the impeller inlet diameter D1, the impeller outlet diameter D2, the blade width b2, and the number of blades Z, with the blades evenly distributed along the circumference;

[0010] Step 2: Set the blade inlet installation angle β1, outlet installation angle β2, and wrap angle Φ to determine the blade inlet edge position P1 and the blade outlet edge position P2;

[0011] Step 3: Obtain the blade control points and draw the blade working surface profile;

[0012] Step 4: Determine the blade thickness and draw the blade profile on the back;

[0013] Step 5: Adjust the geometry of the blade inlet and outlet. Draw the blade inlet edge as a circle, smoothly tangent to the working surface and back surface of the blade. Its radius R is determined by the blade thickness and takes a value of 1-3mm.

[0014] Step 6: Stretch the blade profile, trim the blade inlet, and complete the blade design;

[0015] Step 7: Determine the number, diameter, and location of the balancing holes. The number of balancing holes is the same as the number of blades. Define the angle θ between the line connecting the impeller center and the center of one of the balancing holes and the horizontal line as the circumferential position angle of the balancing hole. The remaining balancing holes are evenly distributed at equal angles in an array to complete the balancing hole design.

[0016] Step 8: Determine the blade tip clearance size. The blade tip clearance is a uniform and constant value, which remains unchanged from the impeller inlet side to the outlet side, thus completing the impeller design.

[0017] Further improvements are made to the method for drawing the blade working surface profile in step three: Draw three circular auxiliary lines. The outermost auxiliary line passes through P2, and the innermost auxiliary line passes through P1. Let the intersection of the middle auxiliary line and the blade be the blade control point P3. Draw an arc with the blade inlet edge position P1 and the control point P3, and then draw an arc with the control point P3 and the blade outlet edge position P2. Ensure that the tangents at P1 and P2 are consistent with the inlet and outlet placement angles β1 and β2, respectively. Smoothly connect the two arcs to obtain the blade working surface profile.

[0018] Further improvements are made to the method of drawing the blade back profile in step four: passing through the three points P1, P2, and P3, draw a line segment with the corresponding thickness as the length of the working surface normal, and the other end point is the point corresponding to the back, thus obtaining the three inlet points Q1, Q2, and Q3 on the back. Draw an arc through the three points, which is the back of the blade.

[0019] Further improvements are made to the blade design process in step six, which is as follows: The blade body is obtained by longitudinally stretching the existing blade profile. Control points P1, P2, P3, Q1, Q2, and Q3 on the lower surface of the blade are stretched to obtain corresponding control points T1, T2, T3, U1, U2, and U3 on the upper surface of the blade. The midpoints A, B, and C of the arc segments T1 and T3, U1 and U3, and Q1 and U1 are taken respectively. A cross-section is created using points A, B, and C to cut and trim the blade body, resulting in the final blade shape and completing the blade design.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. A well-designed blade structure and balance holes can effectively balance the axial force of the impeller.

[0022] 2. The front cover plate of the impeller was removed and the blade inlet was trimmed, widening the flow channel to facilitate cleaning and maintenance inside the pump.

[0023] 3. A double-circular-arc blade was designed, and the inlet and outlet edges of the blade were adjusted to be circular, which optimized the flow structure at the inlet and outlet of the impeller. This uniformly reconstructed the complex flow field at the inlet and outlet of the blade, thereby reducing the hydraulic loss of the impeller and further improving the pump efficiency.

[0024] 4. Simple to manufacture, easy to implement, low processing cost, and convenient for the promotion and application of sanitary pumps. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is an axial view of the sanitary pump impeller.

[0027] Figure 2 This is a schematic diagram of the working surface of a sanitary pump blade.

[0028] Figure 3 This is a schematic diagram of the blades of a sanitary pump.

[0029] Figure 4 This is an axial view of an impeller with circular blade inlet and outlet edges.

[0030] Figure 5 This is a schematic diagram of the blade.

[0031] Figure 6 This is a schematic diagram of the leaf after trimming.

[0032] Figure 7This is a schematic diagram of the balancing hole.

[0033] Figure 8 This is a projection diagram of the blade tip clearance and the impeller axial surface.

[0034] In the figure: 1. Impeller inlet side; 2. Impeller outlet side; 3. Blade; 4. Blade working surface; 5. Blade back side; 6. Blade inlet side; 7. Blade outlet side; 8. Balance hole. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Figure 1 A schematic diagram of the axial section of a sanitary pump impeller proposed in this invention is provided, including an impeller inlet side 1 located in the center and an impeller outlet side 2 surrounding it. A plurality of blades and balancing holes are evenly distributed around the impeller inlet side. The blades 3 are cylindrical blades, including a blade working surface 4, a blade back surface 5, a blade inlet side 6, and a blade outlet side 7; the blade outlet side 7 partially overlaps with the impeller outlet side 2; the blades 3 and balancing holes 8 are evenly distributed in the impeller.

[0037] This embodiment provides a design method for a semi-open impeller of a sanitary pump with specific parameters, including the following steps:

[0038] Step 1: Determine the basic design parameters of the impeller. Impeller inlet diameter D1 = 50mm, impeller outlet diameter D2 = 180mm, blade width b2 = 11mm, number of blades Z = 5, and the blades are evenly distributed circumferentially.

[0039] Step 2: Determine the blade inlet angle β1 = 18°, outlet angle β2 = 30°, and wrap angle Φ = 120°. Based on the impeller inlet and outlet angles and the wrap angle, the inlet position P1 and outlet position P2 of the blade working surface can be preliminarily determined. See [link to relevant documentation]. Figure 2 .

[0040] Step 3: Draw the blade working surface profile. Draw a circular auxiliary line with diameters D2 > D3 > D1, where D3 = 104 mm. Obtain a blade control point P3 on the auxiliary line. Construct an arc between the inlet position point P1 and the control point P3, and then another arc between the control point P3 and the outlet position point P2, ensuring that the tangents at P1 and P2 are consistent with the inlet and outlet installation angles, respectively. Smoothly connect the two arcs to obtain the blade working surface profile. (See [link to documentation]). Figure 2 .

[0041] Step 4: Determine the blade thickness and draw the blade back profile. The blade is set to a non-uniform thickness. The thicknesses at points P1, P2, and P3 are δ1, δ2, and δ3, respectively. The blade thickness should be between 3mm and 6mm, where δ1 = 3mm, δ2 = 5.5mm, and δ3 = 6mm. Draw line segments perpendicular to the working surface profile through these three points, with the corresponding thickness as the length. The other endpoint is the point corresponding to the back profile. This gives the inlet points Q1, Q2, and Q3 on the back profile. Draw an arc through these three points; this represents the back profile of the blade. (See [reference]). Figure 3 .

[0042] Step 5: Adjust the blade inlet and outlet geometry. Draw the blade inlet edge as a circle, smoothly tangent to the blade's working and back surfaces. Its radius R is determined by the blade thickness, R = 1.5mm. The inlet edge is a semicircle, and the outlet edge is a quarter circle. See [link to relevant documentation]. Figure 4 .

[0043] Step Six: Longitudinally stretch the existing blade profile to obtain the blade solid. Control points P1, P2, P3, Q1, Q2, Q3 on the lower surface of the blade are stretched to obtain corresponding control points T1, T2, T3, U1, U2, U3 on the upper surface of the blade. (See [link]). Figure 5 Next, take the midpoints A, B, and C of the arc segments T1 and T3, U1 and U3, and Q1 and U1, respectively. To ensure there are no dead corners inside the impeller and to further improve the flow channel at the impeller inlet, create cross-sections at points A, B, and C to cut and trim the blade solid, obtaining the final blade shape. See [link to documentation]. Figure 6 The blade design was completed.

[0044] Step 7: Determine the number, diameter, and location of the balancing holes. A total of 5 balancing holes are arranged circumferentially on the impeller, with a diameter D... k =6.2mm. The angle θ between the line connecting the impeller center and the center of one of the balancing holes and the horizontal line is defined as the circumferential position angle of the balancing hole. The distance between the center of the balancing hole and the impeller center is D. h Where θ = 40°, D h =60mm. The remaining four balancing holes are evenly distributed at equal angles in an array, see [link / reference]. Figure 7 .

[0045] Step 8: Determine the blade tip clearance dimension. The blade tip clearance δ is a uniform, constant clearance that remains unchanged from the impeller inlet edge to the outlet edge, where δ = 0.5 mm. See [link to relevant documentation]. Figure 8 .

[0046] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, for the device embodiments, the above descriptions are merely preferred embodiments of the present invention. Since they are fundamentally similar to the method embodiments, the descriptions are relatively simple, and relevant parts can be referred to the descriptions of the method embodiments. The above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention, without departing from the principle of the present invention, should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for designing a sanitary pump impeller, the designed sanitary pump impeller structure comprising a centrally located impeller inlet edge and a circumferentially located impeller outlet edge, a plurality of blades and balance holes being evenly distributed around the impeller inlet edge, the blades being non-uniform thickness cylindrical blades comprising a blade inlet edge, a blade working surface, a blade back surface and a blade outlet edge, wherein the blade inlet edge is proximate to the impeller inlet edge, the thickness of the blade gradually increases from the blade inlet edge to the blade outlet edge, and the blade outlet edge partially overlaps with the impeller outlet edge, characterized in that The design methodology includes the following steps: Step 1: Determine the basic design parameters of the impeller, including the impeller inlet diameter D1, the impeller outlet diameter D2, the blade width b2, and the number of blades Z, with the blades evenly distributed along the circumference; Step 2: Set the blade inlet placement angle Exit placement angle and corner Determine the blade inlet edge position P1 and the blade outlet edge position P2; Step 3: Obtain the blade control points and draw the blade working surface profile; The method for drawing the blade working surface profile is as follows: Draw three circular auxiliary lines. The outermost auxiliary line passes through P2 and has a diameter of D2. The innermost auxiliary line passes through P1 and has a diameter of D1. Let the diameter of the middle auxiliary line be D3, where D2 > D3 > D1. Obtain a point P3 on the middle auxiliary line. This point is the intersection of the middle auxiliary line and the blade, i.e., the blade profile control point. Draw an arc with the blade inlet edge position P1 and the control point P3. Then draw another arc with the control point P3 and the blade outlet edge position P2. Ensure that the inlet installation angle at P1 and the outlet installation angle at P2 are respectively the same as the inlet installation angle. and the corner of the exit The blade working surface profile can be obtained by smoothly connecting the two arc segments. Step 4: Determine the blade thickness and draw the blade back profile. Specifically, draw a line segment with the corresponding thickness as the length through the three points P1, P2, and P3, and the other end point is the corresponding point on the back. This will give you the three inlet points Q1, Q2, and Q3 on the back. Draw an arc through these three points, which is the back of the blade. Step 5: Adjust the geometry of the blade inlet and outlet. Draw the blade inlet edge as a circle, smoothly tangent to the working surface and back surface of the blade. Its radius R is determined by the blade thickness and takes a value of 1-3mm. Step Six: Stretch the blade profile, trim the blade inlet, and complete the blade design. Specifically, stretch the existing blade profile longitudinally to obtain the blade body. The control points P1, P2, P3, Q1, Q2, Q3 on the lower surface of the blade are stretched to obtain the corresponding control points T1, T2, T3, U1, U2, U3 on the upper surface of the blade. Take the midpoints A, B, and C of the arc segments T1 and T3, U1 and U3, and Q1 and U1, respectively. Create a cross section at points A, B, and C to cut and trim the blade body to obtain the final blade shape and complete the blade design. Step 7: Determine the number, diameter, and location of the balancing holes. The number of balancing holes should match the number of blades. Calculate the angle between the line connecting the impeller center and the center of one of the balancing holes and the horizontal line. Defined as the circumferential position angle of the balance hole, the remaining balance holes are evenly distributed at equal angles in an array to complete the balance hole design; Step 8: Determine the blade tip clearance size. The blade tip clearance is a uniform and equal clearance that remains constant from the impeller inlet edge to the outlet edge, thus completing the impeller design.

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