CROSS-REFERENCE TO RELATED APPLICATIONS
Pursuant to 35 U.S.C. ยง 119 and the Paris Convention Treaty, this application claims foreign priority to Chinese Patent Application No. 202322028316.9 filed Jul. 31, 2023, the contents of which, including any intervening amendments thereto, are incorporated herein by reference. Inquiries from the public to applicants or assignees concerning this document or the related applications should be directed to: Matthias Scholl P.C., Attn.: Dr. Matthias Scholl Esq., 245 First Street, 18th Floor, Cambridge, MA 02142.
BACKGROUND
The disclosure relates to a centrifugal impeller comprising a plurality of vanes manufactured by sheet metal stamping.
As shown in FIG. 1, a conventional backward centrifugal impeller includes a disk 1a, a cover 2a, and a plurality of vanes 3a produced by sheet metal stamping. The stamping technique introduces elasticity into the material of the plurality of vanes. The elasticity leads to springback, resulting in deviations of the profiles of the plurality of vanes from the intended design, as further detailed below.
A vane is a critical part of a centrifugal impeller, and the profile of the vane is a geometric concept that directly influences the operational efficiency of the centrifugal impeller. For instance, in FIG. 2, a cross-section of the vane is obtained by intersecting the centrifugal impeller with a plane perpendicular to a rotating shaft. In FIG. 3, numerous inscribed circles are drawn within the cross-section, and a vane profile (or median line) is represented by a line connecting the centers of the inscribed circles. The vane is viewed as a plurality of vane profiles stacked vertically, each serving as a fundamental geometric unit of the vane.
In FIG. 4, the geometric parameters of the vane are defined as follows: the vane profile starts where airflow enters and ends where airflow exits. Considering the principles of absolute velocity, relative velocity, and tangential velocity in theoretical physics, it is understood that air moves relative to the vane profile within the centrifugal impeller. By employing the earth as a reference for an absolute coordinate system, the absolute velocity vector of the air is decomposed according to the parallelogram law, allowing for clear depiction of the relationships between the starting point, the ending point, and different velocity vectors during airflow. The air velocity vectors at the starting and the ending points directly influence the magnitude of work done by the vanes. At the starting point of the vane profile: C1 is the absolute velocity of the incoming airflow, W1 is the relative velocity of the incoming airflow, and U1 is the tangential velocity, i.e., the circumferential velocity. At the ending point of the vane profile: C2 is the absolute velocity of the outgoing airflow, W2 is the relative velocity of the outgoing airflow, and U2 is the tangential velocity, i.e., the circumferential velocity. Consequently, an angle between W1 and U1 in the reverse direction defines the inlet angle of the vane, while an angle between W2 and U2 in the reverse direction defines the outlet angle of the vane. The vane undergoes springback during sheet metal stamping, causing plastic deformation or separation to create stamped parts with specific shapes, sizes, and properties. Due to the inherent elastic modulus of the sheet metal, internal stress remains in the stamped parts after plastic deformation. Over time, the internal stress is released, causing the sheet metal to revert slightly towards its original state, resulting in the springback. For the vanes produced by sheet metal stamping, the minimal plastic deformation leads to significant springback, causing the vane shape to deviate from the intended design.
In FIG. 5, the dashed line represents the intended vane profile, while the solid line shows the profile after springback. Due to springback, the starting point and ending point of the vane profile shift, leading to a smaller inlet angle and a larger outlet angle macroscopically.
An excessively large outlet angle of the vane increases the workload of the centrifugal impeller beyond the original design range. Although increased workload can benefit the properties of the centrifugal impeller, the input and output power of the motor also increase. If the input and output power exceed the motor limits, a series of problems may arise, such as excessive motor temperature, reduced motor output efficiency, and accelerated component failure, ultimately lowering overall efficiency, operational reliability, and machine lifespan.
Achieving a vane profile close to the original design requires considering material plasticity, plastic deformation, and multiple die revisions. The revision process relies heavily on experience but still results in some deviations. Predicting exact performance is challenging due to complex interactions between material properties, deformation, and springback, making it hard to guarantee performance alignment in production. Lengthy, partly uncontrollable revisions also impact product delivery schedules.
SUMMARY
To solve the aforesaid problems, one objective of the disclosure is to provide a centrifugal impeller.
The centrifugal impeller comprises a disk, a cover, and a plurality of vanes; the plurality of vanes is disposed between the disk and the cover, and each of the plurality of vanes comprises an inlet edge, an outlet edge, a blade root, and a blade top; a curved corner is disposed at a joint of the outlet edge and the blade top, and the curved corner bends towards a center of a rotation axis L of the centrifugal impeller.
In a class of this embodiment, the outlet edge comprises a vertex A and a point G; the blade top comprises a point H; the vertex A and the point G are connected to form a first curve AG; the vertex A and the point H are connected to form a second curve AH; the point G and the point H are connected to form a third curve GH; the curved corner is formed on each of the plurality of vanes by the first curve AG, the second curve AH, and the third curve GH; and a length of the first curve AG is less than or equal to half of a length of the outlet edge.
In a class of this embodiment, the centrifugal impeller is intercepted by several planes perpendicular to the rotation axis L of the centrifugal impeller and intersecting with the first curve AG, to form a plurality of vane profile lines; the third curve GH and the outlet edge intersect with the plurality of vane profile lines, forming a plurality of curves VO; and lengths of the curves VO increase from the point G to the vertex A.
Also provides is a centrifugal impeller, comprising a disk, a cover, and a plurality of vanes manufactured by sheet metal stamping; the plurality of vanes is disposed between the disk and the cover, and each of the plurality of vanes comprises an inlet edge, an outlet edge, a blade root, and a blade top; a crease line NR is formed in an equidistant offset with respect to the outlet edge, and the crease line NR and the outlet edge form an isometric bending frame, and the isometric bending frame is bent toward the center of the rotation axis L of the centrifugal impeller; the equidistant offset refers to a displacement of each point on the outlet edge along a corresponding vane profile line by a distance.
The following advantages are associated with the centrifugal impeller comprising a plurality of vanes manufactured by sheet metal stamping of the disclosure.
1. The centrifugal impeller features a stabilized shape of the plurality of vanes, reduced springback caused by elastic recovery after sheet metal stamping, and minimized deviation from the intended vane profile.
2. The design of the centrifugal impeller adjusts the parameters of the starting point of the vane profile line and reduces the outlet angle of the vanes to align the outlet airflow angle of the vanes with the intended vane profile after springback. The adjustment minimizes the deviation from the original design specification, preventing the motor input and output from exceeding permissible limits, avoiding detrimental effects such as increased motor temperature, reduced motor output efficiency, and accelerated failure of motor components.
3. The design of the centrifugal impeller reduces the number of mold adjustments, saving on manufacturing and mold costs, significantly increasing mold efficiency, reducing uncontrollable factors, and ensuring vane performance and on-time product delivery.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a conventional impeller;
FIG. 2 is a cross-sectional view of a conventional impeller taken along a plane perpendicular to a rotation axis;
FIG. 3 is a local enlarged view of part A in FIG. 2;
FIG. 4 is a schematic diagram illustrating geometric parameters of a vane profile line in the related art;
FIG. 5 is a comparative diagram showing a vane profile line after springback compared to the original design in the related art;
FIG. 6 is a perspective view of a centrifugal impeller in Example 1 of the disclosure;
FIG. 7 is another perspective view of a centrifugal impeller in Example 1 of the disclosure;
FIG. 8 is an exploded view of a centrifugal impeller in Example 1 of the disclosure;
FIG. 9 is a perspective view of a vane in Example 1 of the disclosure;
FIG. 10 is a schematic diagram of a vane divided into four equal parts in Example 1 of the disclosure;
FIG. 11 is a schematic diagram showing an outlet edge in FIG. 10;
FIG. 12 is a schematic diagram showing a curved plane M extended from a vane in Example 1 of the disclosure;
FIG. 13 is a schematic diagram showing an intersection of a point G located on a vane with a normal plane in Example 1 of the disclosure;
FIG. 14 is a schematic diagram showing a line segment of an intersection between a curved plane M passing through a point G with a normal plane in Example 1 of the disclosure;
FIG. 15 is a schematic diagram showing a curved plane M after rotation around the edge GY in Example 1 of the disclosure;
FIG. 16 is a schematic diagram showing an intersection of a vane with an extended curved plane M in Example 1 of the disclosure;
FIG. 17 is a schematic diagram showing an intersection of a vane profile line with a curved corner in Example 1 of the disclosure;
FIG. 18 is a stereograph of a centrifugal impeller in Example 2 of the disclosure; and
FIG. 19 is a schematic diagram of a vane of a centrifugal impeller in Example 2 of the disclosure.
DETAILED DESCRIPTION
To further illustrate the disclosure, embodiments detailing a centrifugal impeller comprising a plurality of vanes manufactured by sheet metal stamping are described below. It should be noted that the following embodiments are intended to describe and not to limit the disclosure.
Example 1
Referring to FIGS. 6, 7, 8 and 9, the disclosure provides a centrifugal impeller; the centrifugal impeller comprises a disk 200, a cover 300, and a plurality of vanes 100 manufactured by sheet metal stamping; the plurality of vanes 100 are disposed between the disk 200 and the cover 300; each of the plurality of vanes 100 comprises an inlet edge 1, an outlet edge 2, a blade root 3, and a blade top 4; the outlet edge 2 comprises a vertex A and a point G, and the blade top comprises a point H; a first curve AG is formed from the vertex A to the point G, and a second curve AH is formed from the vertex A to the point H; a third curve GH is formed between the point G and the point H; the first curve AG, the second curve AH, and the third curve GH enclose a curved corner 101; the centrifugal impeller further comprises a rotation axis L; and the curved corner is bent towards the center of the rotation axis L.
The length of the first curve AG is not greater than one-half the length of the outlet edge.
The curved corner is bent towards the center of the rotation axis L, as described below:
S1: as shown in FIG. 10, each of the plurality of vanes 100 is enclosed by the inlet edge, the outlet edge, the blade root, and the blade top; from the blade top to the blade root, five vane profile lines are defined and divides each vane into four equal parts, including a first vane profile line a (located at the blade top), a second vane profile line b (located at one-quarter length of each vane), a vane profile line c (located at half length of each vane), a vane profile line d (located at three-quarter length of each vane), and a vane profile line e (located at the blade root); referring to FIG. 11, definitions are given below:
- an ending point of the vane profile line a is located at the vertex A;
- an ending point of the vane profile line b is located at point B; and
- an ending point of the vane profile line c is located at point C;
- S2: a curve BC is formed from the point B to the point C; the point G is located on the curve BC; a scan path GA is formed from the point G to the vertex A, and a curved plane M is drawn along the scan path GA (as described in step 3); referring to FIG. 12, the centrifugal impeller is cut by a plurality of normal planes perpendicular to the rotation axis L, so that a plurality of cross-sectional vane profiles are obtained; and each of the plurality of cross-sectional vane profiles comprises a vane profile line;
- S3: the vane profile line comprises an ending point; on each normal plane along the scan path GA, the ending point is used to represent an origin of a coordinate system, and a tangent to the vane profile line at the ending point is defined as a forward direction of an X-axis; for example, as shown in FIG. 13, the point G is defined as an origin; the curved plane M is intersected by each normal plane along the scan path GA to produce a cross-sectional shape, defined as a line segment of arbitrary length; one endpoint of the line segment is located at the origin; an angle f is formed between the line segment and the forward direction of X-axis; as shown in FIG. 14, the line segment is denoted by GY, and the angle f is formed between the line segment GY and a positive direction of the X-axis; in practical applications, the value of the angle f varies according to the size of the centrifugal impeller, typically ranging from 3 to 10 degrees;
- S4: the line segment GY is located on the curved plane M; as shown in FIG. 15, the curved plane M is rotated around the line segment GY towards the center of the rotation axis L by an angle i, whereby the curved plane M intersects with the vane to form the third curve GH; as shown in FIG. 16, the point H is located on the vane profile line a; in practical applications, the value of angle i varies according to the size of the centrifugal impeller, typically ranging from 3 to 6 degrees; and
- S5: as shown in FIG. 16, a region AGH (i.e., the curved corner 101) is bent towards the curved plane M and coincides with the curved plane M; and the resulting vane profile line is close to the intended design.
The disclosed centrifugal impeller features a reduced outlet angle of the curved corner by the angle f; however, due to significant vane deformation along the scan path GA, the vane profile lines vary in bending lengths, resulting in increased vane workload. Specifically, closer to the point A, where the vane deformation is greater, the bending lengths of the vane profile lines are longer. As shown in FIG. 17, the centrifugal impeller is intercepted by several planes perpendicular to the rotation axis L of the centrifugal impeller and intersecting with the first curve AG, to form a plurality of vane profile lines. The third curve GH and the outlet edge 2 intersect with the plurality of vane profile lines, forming a plurality of curves VO; the lengths of the curves VO increase from the point G to the vertex A; and at the point G, the length of the curve VO is zero.
1. The centrifugal impeller features a stabilized shape of the plurality of vanes, reduced springback caused by elastic recovery after sheet metal stamping, and minimized deviation from the intended vane profile.
2. The design of the centrifugal impeller adjusts the parameters of the starting point of the vane profile line and reduces the outlet angle of the vanes to align the outlet airflow angle of the vanes with the intended vane profile after springback. The adjustment minimizes the deviation from the original design specification, preventing the motor input and output from exceeding permissible limits, avoiding detrimental effects such as increased motor temperature, reduced motor output efficiency, and accelerated failure of motor components.
3. The design of the centrifugal impeller reduces the number of mold adjustments, saving on manufacturing and mold costs, significantly increasing mold efficiency, reducing uncontrollable factors, and ensuring vane performance and on-time product delivery.
Example 2
As shown in FIGS. 18-19, the disclosure also provides a centrifugal impeller, comprising a disk 200, a cover 300, and a plurality of vanes 100 manufactured by sheet metal stamping; the plurality of vanes 100 is disposed between the disk 200 and the cover 300, and each of the plurality of vanes 100 comprises an inlet edge 1, an outlet edge 2, a blade root 3, and a blade top 4; a crease line NR is formed in an equidistant offset with respect to the outlet edge 2, and the crease line NR and the outlet edge form an isometric bending frame 103, and the isometric bending frame 103 is bent toward the center of the rotation axis L of the centrifugal impeller.
The equidistant offset refers to a displacement of each point on the outlet edge along a corresponding vane profile line 5 by a distance E.
The centrifugal impeller features a stabilized shape of the plurality of vanes, reduced springback caused by elastic recovery after sheet metal stamping, and minimized deviation from the intended vane profile.
It will be obvious to those skilled in the art that changes and modifications may be made, and therefore, the aim in the appended claims is to cover all such changes and modifications.
Patent Application
20250043798
