A medium-high specific speed single-stage power type centrifugal impeller and a centrifugal pump using the same

Abstract

The utility model relates to a kind of monotonic power type centrifugal impeller of medium-high specific speed and centrifugal pump applying it, solve the problems, such as the characteristic that power cannot present monotone increasing when high specific speed or need additional structure or component to generate high cost of prior art, the technical scheme used includes front cover, back cover, the equal angle distribution of several blades along circumferential direction being set between the front cover and back cover, it is characterized in that the blade is backward-inclined twisted blade, the convex surface of the blade is pressure surface, the concave surface of the blade is non-pressure surface, the water outlet end of the blade is axially inclined arrangement, parallel line parallel to impeller axis is made through the water outlet end surface of the blade, the water outlet end surface of the blade and the parallel line between there is included angle α, 0°≤α≤30°.Its effect: change the shape of blade, so that the impeller of medium-high specific speed presents monotone increasing characteristic, and does not additionally increase external structure or component, can effectively control reasonable cost.

Description

Technical Field

[0001] This utility model relates to the field of water pumps and their accessories, and in particular to a medium-to-high specific speed monotonic power centrifugal impeller and a centrifugal pump using the same. Background Technology

[0002] Traditional low-specific-speed centrifugal pumps exhibit a power curve that monotonically increases with flow rate, while high-specific-speed axial-flow pumps show a power curve that monotonically decreases with flow rate. Traditional medium-to-high specific-speed centrifugal pumps have power curves that fall between these two extremes, rising initially and then falling, resulting in power extremes—the power value corresponding to the highest point of the curve. Especially for the speed control principle of permanent magnet variable frequency canned motor pumps, which involves sensing the pump's current flow rate, there are currently two main technical methods. One method relies on the power curve, requiring the pump's operating power curve to be monotonic. For example, the patent CN102734184A, titled "Method and Device for Estimating Pump Flow Rate," points out that when the power curve is not continuously increasing at high flow rates (ΔP2, ΔQ2), one power value corresponds to several flow rates. Therefore, the QP curve-based method is unusable or inaccurate at high flow rates. The second method uses pressure sensors, combining the pump inlet and outlet pressure difference with speed information, which introduces additional structural and component costs. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned problems existing in the prior art by providing a medium-to-high specific speed monotonic power centrifugal impeller and a centrifugal pump using it. By changing the shape of the blades, the convex surface of the blades is made into a pressure surface and the concave surface into a non-pressure surface. The outlet end of the blades is axially inclined and forms a certain angle with a parallel line parallel to the axis. This allows the medium-to-high specific speed impeller to exhibit a monotonic increasing characteristic without adding any external structures or components, thus effectively controlling reasonable costs.

[0004] The above-mentioned technical objectives of this utility model are mainly achieved through the following technical solutions:

[0005] The technical solution of the first technical subject of this utility model is as follows: a medium-high specific speed monotonic power centrifugal impeller, including a front cover plate and a rear cover plate, and a plurality of blades arranged at equal angles along the circumference between the front cover plate and the rear cover plate. The blades are backward-inclined twisted blades, the convex surface of the blades is the pressure surface, the concave surface of the blades is the non-pressure surface, the water outlet end of the blades is axially inclined, and a parallel line parallel to the impeller axis is drawn through the water outlet end surface of the blades. The water outlet end surface of the blades and the parallel line have an included angle α, 0°≤α≤30°.

[0006] The difference between this technical solution and the existing technology is that the shape of the blade is changed so that the convex surface of the blade is the pressure surface and the concave surface is the non-pressure surface. The water outlet end of the blade is axially inclined and forms a certain angle with the parallel line parallel to the axis. This makes the impeller with medium and high specific speed exhibit a monotonically increasing characteristic, and it does not require additional external structures or components, which is conducive to controlling reasonable costs.

[0007] As a further improvement and supplement to the above technical solution, the present invention adopts the following technical measures:

[0008] Preferably, the number of blades is 6 to 10.

[0009] Preferably, the impeller rotates in the opposite direction to the blades.

[0010] Preferably, the cross-section of the inlet end of the blade has a sharp corner and a rounded corner, the rounded corner being configured to correspond to the non-pressure surface of the blade, and the sharp corner being configured to correspond to the pressure surface of the blade.

[0011] As a priority, a tangent line L1 is drawn from point A, where the water outlet end of the blade mates with the rear cover plate, to the pressure surface of the adjacent blade. The tangent point on the pressure surface of the blade is located at position B, where the water inlet end of the blade mates with the front cover plate. Position B is the extreme position of the blade.

[0012] As a priority, when the tangent point on the pressure surface of the blade is located at position C where the water inlet end of the blade mates with the front cover plate, position C is located between position B and the water outlet of the impeller, and the angle γ between the tangent line L2 passing through position C and the tangent line L1 is 0°≤γ≤10°.

[0013] As a priority, when the tangent point on the pressure surface of the blade is located at position C where the inlet end of the blade mates with the front cover plate, position C is located between position B and the outlet of the impeller. Position C corresponds to the position on the center arc of the blade as position C'. The distance from position C' to the inlet end of the blade is 1 / n of the total arc length of the blade, where 10 ≤ n.

[0014] As a preferred embodiment, the non-pressure surface covers the pressure surface of the blade's projection onto the rear cover plate.

[0015] As a priority, the projection area of ​​each blade on the rear cover plate gradually decreases from the water inlet end of the blade towards the water outlet end.

[0016] The technical solution of the second technical subject of this utility model is: a centrifugal pump, including a pump body, a centrifugal impeller disposed in the pump body, and a motor that drives the centrifugal impeller to work, characterized in that the centrifugal impeller is the aforementioned medium-high specific speed monotonic power type centrifugal impeller.

[0017] The beneficial effects of this utility model are as follows: 1. By changing the shape of the blade, making the convex surface of the blade the pressure surface and the concave surface the non-pressure surface, and setting the water outlet end of the blade axially inclined at a certain angle with a parallel line parallel to the axis, the impeller with medium to high specific speed exhibits a monotonically increasing characteristic without adding external structures or components, effectively controlling reasonable costs. 2. By setting the extreme positions of the blade and a certain distance above the extreme positions, the twisted blade can pass through the mold scheme of the straight-out slider for easy mold opening, thereby reducing the mold cost of the twisted blade and reducing water inlet impact loss. 3. By setting the blade shape so that the projection of the blade on the rear cover plate shows the non-pressure surface covering the pressure surface, and the projection area gradually decreases from the water inlet end of the blade to the water outlet end, which is conducive to further facilitating mold opening and reducing water inlet impact loss. 4. By controlling the included angle α and adjusting the number of blades, it is possible to increase the head at high flow rates without affecting the hydraulics or with minimal impact, while also achieving the monotonicity of the power curve to facilitate the control of pumps with high specific speed monotonic power centrifugal impellers in applications. Attached Figure Description

[0018] Figure 1 This is a front view structural schematic diagram of a centrifugal impeller involved in this utility model.

[0019] Figure 2 yes Figure 1 A schematic diagram of the structure viewed from below.

[0020] Figure 3 This is a cross-sectional structural schematic diagram of this utility model.

[0021] Figure 4 yes Figure 3 Enlarged structural diagram of section D in the middle.

[0022] Figure 5 This is a schematic diagram of the power curve of the centrifugal pump involved in this utility model during operation.

[0023] In the figure: 1. Front cover plate; 2. Rear cover plate; 3. Blade; 4. Pressure surface; 5. Non-pressure surface; 6. Sharp corner; 7. Rounded corner; 8. Blade in extreme position; 9. Feasible blade; 10. Blade of the prior art; 11. Ridge. Detailed Implementation

[0024] The technical solution of this utility model will be further described in detail below through embodiments and in conjunction with the accompanying drawings. The directions "up" and "down" mentioned herein are relative to... Figure 1 In terms of above and below.

[0025] Example 1: Technical solution of the first technical subject of this utility model:

[0026] like Figures 1-5 As shown, a medium-to-high specific speed monotonic power centrifugal impeller includes a front cover plate 1, a rear cover plate 2, and a plurality of blades 3 disposed between the front cover plate 1 and the rear cover plate 2 and distributed at equal angles along the circumference.

[0027] The difference between this technical solution and the prior art is that: the blade 3 is a backward-curved twisted blade, the convex surface of the blade 3 is the pressure surface 4, the concave surface of the blade 3 is the non-pressure surface 5, the water outlet end of the blade 3 is axially inclined, and a parallel line parallel to the impeller axis is drawn through the water outlet end surface of the blade 3, and there is an angle α between the water outlet end surface of the blade 3 and the parallel line, 0°≤α≤30°.

[0028] In practical applications, α can take values ​​of 15°, 18°, 20°, 22°, and 25°.

[0029] The difference between this technical solution and the prior art is that the shape of the blade 3 is changed so that the convex surface of the blade 3 is the pressure surface 4 and the concave surface is the non-pressure surface 5. The water outlet end of the blade 3 is axially inclined and forms a certain angle with the parallel line parallel to the axis. This makes the impeller with medium and high specific speed exhibit a monotonically increasing characteristic, and does not require additional external structures or components, which is conducive to controlling reasonable costs.

[0030] The centrifugal pump employing the medium-to-high specific speed monotonic power centrifugal impeller described in this technical solution exhibits a power curve that monotonically increases with flow rate at medium-to-high specific speeds (e.g., ...). Figure 5 (As shown).

[0031] The above technical solution will then be elaborated and supplemented to make it more complete:

[0032] In practical applications, the number of blades 3 is 6 to 10. In this embodiment, the number of blades 3 is preferably 6, 8, or 9.

[0033] In practical applications, the impeller rotates in the opposite direction to the bending direction of the blades 3. That is, as shown... Figure 1 As shown, the impeller rotates counterclockwise upwards, while the blade 3 bends downwards.

[0034] In practical applications, the cross-section of the water inlet end of the blade 3 has a sharp angle 6 and a rounded angle 7. The rounded angle 7 corresponds to the non-pressure surface 5 of the blade 3, and the sharp angle 6 corresponds to the pressure surface 4 of the blade 3. Thus, the water inlet end of each blade 3 has a ridge line 11 on one side of the pressure surface 4.

[0035] In practical applications, a tangent L1 is drawn from point A, where the water outlet end of the blade 3 mates with the rear cover plate 2, to the pressure surface 4 of the adjacent blade 3. The tangent point on the pressure surface 4 of the blade 3 is located at position B, where the water inlet end of the blade 3 mates with the front cover plate 1. Position B is the extreme position of the blade 3. The blade involved in this technical solution is the blade 8 at its extreme position. Compared with the blade 10 of the prior art, the wrap angle of the blade 8 at its extreme position is reduced, and the degree of bending is decreased.

[0036] In practical applications, when the tangent point on the pressure surface 4 of the blade 3 is located at position C where the water inlet end of the blade 3 mates with the front cover plate 1, position C is located between position B and the outlet of the impeller, and the angle γ between the tangent line L2 passing through position C and the tangent line L1 is 0°≤γ≤10°.

[0037] In practical applications, when the tangent point on the pressure surface 4 of the blade 3 is located at position C where the water inlet end of the blade 3 mates with the front cover plate 1, position C is located between position B and the outlet of the impeller. Position C corresponds to the position on the center arc of the blade 3 as position C'. The distance from position C' to the water inlet end of the blade 3 is 1 / n of the total arc length of the blade 3, where 10 ≤ n.

[0038] In other words, when blade 3 is in its extreme position, in a top-down view (such as...) Figure 1 , Figure 3 and Figure 4 As shown), a tangent line L1 is drawn at point A where the water outlet end of the blade 3, which is adjacent to the pressure surface 4, mates with the water inlet end of the blade 3. The tangent point is located at the point where the water inlet end of the front cover 1 mates with the blade 3 (i.e., position B).

[0039] When the tangent L1 cannot be tangent to the inlet end of blade 3, such as Figure 4 and Figure 5(The figure shows a schematic diagram of removing the front cover plate 1 and illustrates the adjustment of the water inlet end.) As shown, when the wrap angle of the blade 3 is large, the degree of curvature of the blade 3 is high (such as the blade 10 in the prior art). The tangent point generated by the tangent line L1 passing through point A is only near the water inlet end, not at the mating point between the front cover plate 1 and the water inlet end of the blade 3 (i.e., position B). Therefore, it is necessary to adjust the shape of the water inlet end of the blade 3 so that the water inlet end of the blade 3 fits the tangent line L1. The blade that fits the tangent line L1 is the blade 8 at the extreme position, which is the state that this technical solution needs to achieve.

[0040] When the blade 3 is in the extreme position, at the position of the ridge line 11 of each blade 3, the tangent L3 at each section (radial) of each blade 3 is parallel to and remains parallel to the tangent L1.

[0041] When the wrap angle of blade 3 is small (i.e., the water inlet end of blade 3 is located above the water inlet end of blade 10 in the prior art), a tangent line that is tangent to the water inlet end of the pressure surface of the blade cannot be drawn at point A. Therefore, no processing is required, which is in line with the purpose of this technical solution.

[0042] When the wrap angle of blade 3 is large (as shown in blade 10 of the prior art), the wrap angle is large and blade 3 is more curved. Therefore, the water inlet end of blade 3 needs to be moved upward to reduce the wrap angle so that the blade reaches the requirement of blade 8 at the limit position or reaches the requirement of a certain distance above blade 8 at the limit position.

[0043] The above design allows the twisted blades to be molded using a straight-out slider mold scheme, which facilitates mold opening, thereby reducing the mold cost of the twisted blades and reducing water ingress impact loss.

[0044] In practical applications, in order to facilitate mold opening and reduce water ingress impact losses, the projection of the blade 3 on the rear cover plate 2, and the non-pressure surface 5 covering the pressure surface 4.

[0045] In practical applications, in order to facilitate further mold opening and reduce water inrush loss, the projection area of ​​each blade 3 on the rear cover plate 2 gradually decreases from the water inlet end to the water outlet end.

[0046] Example 2: Technical solution of the second technical subject matter involved in this utility model:

[0047] A centrifugal pump includes a pump body, a centrifugal impeller disposed within the pump body, and a motor that drives the centrifugal impeller.

[0048] The difference between this technical solution and the prior art is that the centrifugal impeller is the medium-high specific speed monotonic power type centrifugal impeller described in Example 1. This centrifugal impeller possesses all the beneficial technical effects of the medium-high specific speed monotonic power type centrifugal impeller.

[0049] Furthermore, by controlling the included angle α and adjusting the number of blades 3, it is possible to increase the head at high flow rates without affecting the hydraulics or with minimal impact, while also achieving the monotonicity of the power curve to facilitate the control of pumps with high specific speed monotonic power centrifugal impellers in applications.

[0050] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Various modifications and variations can be made to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A single-stage centrifugal impeller of medium-high specific speed and constant power, comprising a front cover plate (1), a rear cover plate (2), a number of blades (3) distributed at equal angles in the circumferential direction, arranged between the front cover plate (1) and the rear cover plate (2), characterized in that The blade (3) is a backward-inclined twisted blade (3). The convex surface of the blade (3) is the pressure surface (4), and the concave surface of the blade (3) is the non-pressure surface (5). The water outlet end of the blade (3) is axially inclined. A parallel line parallel to the impeller axis is drawn through the water outlet end surface of the blade (3). The water outlet end surface of the blade (3) and the parallel line have an angle α, 0°≤α≤30°.

2. The single-pitch centrifugal impeller of medium specific speed according to claim 1, characterised in that The number of blades (3) is 6 to 10.

3. The single-stage power type centrifugal impeller of medium specific speed according to claim 2, characterised in that The impeller rotates in the opposite direction to the bending direction of the blade (3).

4. A single-stage centrifugal impeller of medium specific speed according to any one of claims 1-3, characterised in that The cross-section of the water inlet end of the blade (3) has a sharp corner (6) and a rounded corner (7). The rounded corner (7) is set in correspondence with the non-pressure surface (5) of the blade (3), and the sharp corner (6) is set in correspondence with the pressure surface (4) of the blade (3).

5. A single-stage centrifugal impeller of medium specific speed according to any one of claims 1-3, characterised in that Draw a tangent L1 on the pressure surface (4) of the adjacent blade (3) at point A where the water outlet end of the blade (3) mates with the rear cover plate (2). The tangent point on the pressure surface (4) of the blade (3) is located at position B where the water inlet end of the blade (3) mates with the front cover plate (1). Position B is the extreme position of the blade (3).

6. The single-stage power type centrifugal impeller of a medium-high specific speed according to claim 5, characterised in that When the tangent point on the pressure surface (4) of the blade (3) is located at position C where the water inlet end of the blade (3) mates with the front cover plate (1), position C is located between position B and the outlet of the impeller, and the angle γ between the tangent line L2 passing through position C and the tangent line L1 is 0°≤γ≤10°.

7. The single-stage power type centrifugal impeller of a medium specific speed according to claim 5, characterized in that When the tangent point on the pressure surface (4) of the blade (3) is located at position C where the water inlet end of the blade (3) mates with the front cover plate (1), position C is located between position B and the outlet of the impeller. Position C corresponds to the position on the center arc of the blade (3) as position C'. The distance from position C' to the water inlet end of the blade (3) is 1 / n of the total arc length of the blade (3), where 10 ≤ n.

8. The single-stage moderate specific speed centrifugal impeller of positive displacement type according to any of claims 1 - 3, characterised in that The projection of the blade (3) on the rear cover plate (2), and the non-pressure surface (5) covering the pressure surface (4).

9. The single-stage power type centrifugal impeller of medium specific speed according to claim 8, characterised in that The projection area of ​​each blade (3) on the rear cover plate (2) gradually decreases from the water inlet end to the water outlet end of the blade (3).

10. A centrifugal pump comprising a pump body, a centrifugal impeller disposed within the pump body, and a motor driving the centrifugal impeller in operation, characterized in that The centrifugal impeller is a medium-high specific speed monotonic power type centrifugal impeller as described in any one of claims 1-9.

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