Impeller for radial-flow heat dissipating fan

1. An impeller for a radial-flow heat dissipating fan, comprising:

a hub having a circumference;

a plurality of blades surrounding the hub, the blades including a first blade set and a second blade set; and

at least one connecting member connecting the blades to the circumference of the hub and separating the blades from the circumference of the hub, said at least one connecting member comprising at least one rib;

the impeller including an air inlet side and a bottom side, wherein blades of the first blade set and the second blade set have a bottom edge located at the bottom side, and the blades of the first blade set extend beyond the blades of the second blade set at the air inlet side such that distribution of the blades at the air inlet side of the impeller is sparser than that at the bottom side of the impeller, thereby increasing an air inlet amount.

2. The impeller as claimed in claim 1 , wherein each said blade of the first blade set includes an air inlet side edge, the air inlet side edges of the blades having different axial levels to form the sparser distribution of the blades at the air inlet side of the impeller.

3. The impeller as claimed in claim 1 , wherein the blades include a plurality of higher blades to form the first blade set and a plurality of shorter blades to form the second blade set, the number of the shorter blades being more than that of the higher blades to form the sparser distribution of the blades at the air inlet side of the impeller.

4. The impeller as claimed in claim 1 , wherein some of the blades have an axial level higher than the hub, forming a buffering space between the blades and a top face of the hub for increasing the air inlet area and for assisting in change of axial incoming airflow into centrifugal airflow.

5. The impeller as claimed in claim 1 , wherein the impeller comprises an annular plate extending from the circumference of the hub to form the connecting member, and wherein said blades are mounted on a side of the annular plate.

6. An impeller for a radial-flow heat dissipating fan, comprising:

a hub having a circumference;

a plurality of blades surrounding the hub, the blades including a first blade set and a second blade set; and

at least one connecting member connecting the blades to the circumference of the hub and separating the blades from the circumference of the hub;

the impeller including an air inlet side and a bottom side, wherein blades of the first blade set and the second blade set have a bottom edge located at the bottom side, and the blades of the first blade set extend beyond the blades of the second blade set at the air inlet side such that distribution of the blades at the air inlet side of the impeller is sparser than that at the bottom side of the impeller, thereby increasing an air inlet amount; and

wherein the impeller further comprises a connecting ring extending across an air inlet side edge of each said blade which is disconnected from the outer circumference of the hub.

7. The impeller as claimed in claim 6 , wherein the impeller further comprises another connecting ring extending across the bottom edge of each said blade.

8. The impeller as claimed in claim 7 , wherein the impeller further comprises at least one supporting member to form the connecting member connected between the circumference of the hub and at least one of the blades.

9. The impeller as claimed in claim 6 , wherein the impeller further comprises at least one supporting member to form the connecting member connected between the circumference of the hub and at least one of the blades.

10. An impeller for a radial-flow heat dissipating fan, comprising:

a hub having a circumference;

a plurality of blades surrounding the hub, the blades including a first blade set and a second blade set; and

at least one connecting member connecting the blades to the circumference of the hub and separating the blades from the circumference of the hub;

the impeller including an air inlet side and a bottom side, wherein blades of the first blade set and the second blade set have a bottom edge located at the bottom side, and the blades of the first blade set extend beyond the blades of the second blade set at the air inlet side such that distribution of the blades at the air inlet side of the impeller is sparser than that at the bottom side of the impeller, thereby increasing an air inlet amount, and

wherein the impeller further comprises a connecting ring extending across a bottom edge of each said blade.

11. The impeller as claimed in claim 10 , wherein the impeller further comprises at least one supporting member to form the connecting member connected between the circumference of the hub and at least one of the blades.

12. An impeller, for a radial-flow heat dissipating fan, comprising:

a hub having a circumference;

a plurality of blades surrounding the hub, the blades including a first blade set and a second blade set; and

at least one connecting member connecting the blades to the circumference of the hub and separating the blades from the circumference of the hub;

the impeller including an air inlet side and a bottom side, wherein blades of the first blade set and the second blade set have a bottom edge located at the bottom side, and the blades of the first blade set extend beyond the blades of the second blade set at the air inlet side such that distribution of the blades at the air inlet side of the impeller is sparser than that at the bottom side of the impeller, thereby increasing an air inlet amount;

wherein the blades include a plurality of higher blades to form the first blade set and a plurality of shorter blades to form the second blade set, the number of the shorter blades being more than that of the higher blades to form the sparser distribution of the blades at the air inlet side of the impeller; and

wherein the impeller further comprises a connecting ring separating some of the blades to form upper blades and lower blades.

13. An impeller for a radial-flow heat dissipating fan, comprising:

a hub having a circumference;

a plurality of blades, each longitudinally extending along an axis of the hub, the blades varying in heights along the axis of the hub; and

at least one connecting member connecting the blades to the circumference of the hub and separating the blades from the circumference of the hub, said at least one connecting member comprising at least one rib;

the impeller further including an air inlet side and a bottom side, wherein some of the blades longitudinally extend beyond other blades at the air inlet side.

14. The impeller as claimed in claim 13 , wherein each said blade includes an air inlet side edge and a bottom edge, the air inlet side edges of the blades having various heights.

15. The impeller as claimed in claim 13 , wherein the blades include a plurality of higher blades to form a first blade set and a plurality of shorter blades to form a second blade set, the number of the shorter blades being more than that of the higher blades.

16. The impeller as claimed in claim 13 , wherein the impeller further comprises a connecting ring extending across an air inlet side edge of each said blade.

17. An impeller for a radial-flow heat dissipating fan, comprising:

a hub having a circumference;

a plurality of blades, each longitudinally extending along an axis of the hub, the blades varying in heights along the axis of the hub; and

at least one connecting member connecting the blades to the circumference of the hub and separating the blades from the circumference of the hub;

the impeller further including an air inlet side and a bottom side, wherein some of the blades longitudinally extend beyond other blades at the air inlet side;

wherein the impeller further comprises a connecting ring extending across a bottom edge of each said blade.

18. The impeller as claimed in claim 17 , wherein the impeller further comprises at least one supporting member to form the connecting member connected between the circumference of the hub and at least one of the blades.

19. The impeller as claimed in claim 17 , wherein the impeller comprises an annular plate extending from the circumference of the hub to form the connecting member, and wherein said blades are mounted on a side of the annular plate.

20. An impeller, for a radial-flow heat dissipating fan, comprising:

a hub having a circumference;

a plurality of blades, each longitudinally extending along an axis of the hub, the blades varying in heights along the axis of the hub; and

at least one connecting member connecting the blades to the circumference of the hub and separating the blades from the circumference of the hub;

the impeller further including an air inlet side and a bottom side, wherein some of the blades longitudinally extend beyond other blades at the air inlet side;

wherein the impeller further comprises a connecting ring separating some of the blades to form upper blades and lower blades.