Centrifugal pump with outlet flow passage of increasing cross-section
A centrifugal pump includes a motor having an output shaft, a volute mounted at one side of the motor and an impeller which is located inside the volute and attached to the output shaft. The volute has an inlet arranged along the axial direction, an oulet arranged along the lateral direction and a flow channel arranged along the circumferential direction. The flow channel has a spiral shape. The cross-sectional area of the flow channel increases towards the outlet.
1. A centrifugal pump, comprising:
a motor having a shaft;
an impeller attached to the shaft of the motor; and
a monolithic volute comprising:
a chamber enclosing the impeller;
an inlet along an axial direction of the shaft of the motor and communicating with the chamber;
a spiral flow channel communicating with the chamber and having a spiral inner wall with a decreasing radius of curvature between a first end and a second end along a flow direction;
an outlet passage having a first end coupled to the second end of the spiral flow channel and a second end; and
an outlet connected to the second end of the outlet passage,
wherein the outlet passage has an inner wail and an outer wall both being inclined with respect to a center line of the outlet, an outlet inner spreading angle formed between the inner wall of the outlet passage and the center line of the outlet being less than an outlet outer spreading angle formed between the outer wall of the outlet passage and the center line of the outlet.
2. The centrifugal pump of claim 1 , wherein the flow channel has a cross section with a dimension along a radial direction of the chamber perpendicular to the shaft of the motor that increases in the flow direction.
3. The centrifugal pump of claim 2 , wherein the cross section of the flow channel has another dimension parallel to the shaft of the motor that increases in the flow direction.
4. The centrifugal pump of claim 1 , wherein a ratio between a distance formed between an inlet center and the inner wall of the flow channel and an outer radius of the impeller is between 0.8 ˜1.2.
5. The centrifugal pump of claim 1 , wherein:
the outlet passage has an inner wall and an outer wall; and
the outlet inner spreading angle between the inner wall and the center line of the outlet is between 5 degrees and 10 degrees; and
the outlet outer spreading angle between the outer wall and the center line of the outlet is between 5 degrees and 10 degrees.
6. The centrifugal pump of claim 5 , wherein the outlet outer spreading angle is 8.8 degrees and the outlet inner spreading angle is 6.5 degrees.
7. The centrifugal pump of claim 1 , wherein the impeller comprises a base plate, a hub arranged at the center of the base plate and a plurality of blades arranged on the base plate.
8. The centrifugal pump of claim 7 , wherein the hub has a conical shape and the ratio between the radius of the bottom of the hub and the outer radius of the base plate is between 0.3 ˜0.5.
9. The centrifugal pump of claim 7 , wherein blade outlet angles of the blades are between 15 ˜30 degrees.
10. The centrifugal pump of claim 9 , wherein the blade outlet angles are 15 degrees.
11. The centrifugal pump of Claim 1 , wherein the flow channel has a top wall which extends along a spiral path so that a height of the flow channel increases in the flow direction.
12. The centrifugal pump of claim 11 , wherein a width of the flow channel increases in the direction of flow towards the outlet.
13. The centrifugal pump of claim 1 , wherein the spiral flow channel surrounds the impeller less than 360 degrees.