Impeller

Abstract

An impeller includes a hub having a top portion and an annular wall extending from a circumference of the top portion in a direction perpendicular to the top portion. The top portion includes a shaft base for coupling with a shaft located in an inner space defined by the top portion and the annular wall. A plurality of blades are mounted to an outer periphery of the annular wall. A metal ring is mounted in the inner space of the hub. The annular wall has a thickness substantially smaller than that of the top portion, allowing the metal ring to be inserted into the inner space by tight coupling.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an impeller and, more particularly, to an impeller including a hub having a top portion and an annular wall with a thickness smaller than that of the top portion to allow easy manufacture while saving material costs.

2. Description of Related Art

FIGS. 1 and 2 show a conventional impeller including a rotor 7 having a hub 71 and a plurality of blades 72. The blades 72 are annularly spaced and formed on an outer periphery of an annular wall 711 of the hub 71. A shaft 73 is fixed to a center of the hub 71. The thickness of a top portion of the hub 71 is substantially the same as that of the annular wall 711 thereof. A plurality of engaging ribs 712 is axially formed on an inner periphery of the annular wall 711. A metal ring 8 includes increasing diameters from a first end 81 thereof toward a second end 82 thereof. The first end 81 of the metal ring 8 includes an annular lip 83 extending radially inward. A magnetic ring 9 is received in the metal ring 8, engaged with an inner periphery of the metal ring 8, and abuts against the annular lip 83.

With reference to FIGS. 1 and 2, an outer diameter of the first end 81 of the metal ring 8 is slightly smaller than an inner diameter defined by the ribs 712 of the hub 71, and an outer diameter of the second end 82 of the metal ring 8 is slightly larger than the inner diameter defined by the ribs 712 of the hub 71. Thus, the first end 81 of the metal ring 8 can easily enter an inner space defined by the annular wall 711 when the metal ring 8 is inserted into the rotor 7. The metal ring 8 is forcibly inserted into the inner space with an external force until the metal ring 8 is completely received in the hub 71. At this time, the second end 82 of the metal ring 8 is positioned between the ribs 712 by tight coupling, forming a plastic impeller. Such an impeller is disclosed in for example Taiwan Utility Model Publication No. 562332.

However, since the top portion of the hub 71 must have a sufficient thickness to avoid breakage resulting from stress concentration in a location at a bend adjacent to the center of the hub 71 and since the thickness of the annular wall 711 of the hub 71 is substantially the same as that of the top portion of the hub 71, the ribs 712 are necessary on the inner periphery of the annular wall 711 to provide plastic deformation capability for the purposes of tightly positioning the metal ring 8 in the annular wall 711. As a result, additional and special processing on the metal ring 8 is required to provide the metal ring 8 with various diameters at two ends thereof. Namely, more processing jobs prior to assembly are needed and, thus, lead to difficult manufacture.

It is, therefore, a need of an impeller that can be manufactured and assembled easily.

OBJECTS OF THE INVENTION

The primary object of the present invention is to provide an impeller that includes a hub having an annular wall with a thickness substantially smaller than that of a top portion of the hub. The substantial thickness of the annular wall of the hub is reduced to enhance its plastic deformation capability for allowing assembly with a metal ring that is inserted into the hub by tight coupling. The impeller according to the preferred teachings of the present invention can be easily manufactured while saving material costs.

SUMMARY OF THE INVENTION

An impeller according to the preferred teachings of the present invention includes a hub having a top portion and an annular wall extending from a circumference of the top portion in a direction perpendicular to the top portion. The top portion and the annular wall together define an inner space. The top portion includes a shaft base adapted for coupling with a shaft located in the inner space. A plurality of blades are mounted to an outer periphery of the annular wall. A metal ring is mounted in the inner space of the hub. The annular wall has a thickness substantially smaller than that of the top portion, allowing the metal ring to be inserted into the inner space by tight coupling.

Preferably, the annular wall includes at least one positioning portion extending inward from an inner periphery of the annular wall. The at least one positioning portion abuts with an outer end of the metal ring distant to the top portion of the hub to retain the metal ring in the inner space.

Preferably, the metal ring includes a compartment adapted for receiving an annular magnet.

Preferably, the metal ring further includes an annular lip extending radially inward form an inner end thereof adjacent to the top portion of the hub. The annular lip abuts with an end of an annular magnet mounted in the metal ring.

Other objects, advantages and novel features of this invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded cross sectional view of a conventional impeller;

FIG. 2 shows a cross sectional view of the conventional impeller of FIG. 1 after assembly;

FIG. 3 shows an exploded perspective view of an impeller of a first embodiment according to the preferred teachings of the present invention;

FIG. 4 shows an exploded sectional view of the impeller of FIG. 3;

FIG. 5 shows a cross sectional view of the impeller of FIG. 3 after assembly; and

FIG. 6 shows a cross sectional view of an impeller of a second embodiment according to the preferred teachings of the present invention after assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An impeller 1 of a first embodiment according to the preferred teachings of the present invention is shown in FIGS. 3-5. The impeller 1 is integrally formed by injection molding of a plastic material such as polyphenylene sulfide, polypropylene, resin, or polyester ester ketone. The impeller 1 can be an axial flow impeller or a blower type impeller. In the embodiment shown, the impeller 1 is an axial flow impeller. The impeller 1 includes a hub 11, a plurality of blades 12, and a shaft 13. The hub 11 is substantially cylindrical or tubular. The blades 12 are provided on an outer periphery of the hub 11 and spaced from each other at regular intervals. The shaft 13 is mounted to a center of the hub 11.

With reference to FIGS. 3 and 4, the hub 11 of the first embodiment includes a top portion 111 and an annular wall 112 extending from a circumference of the top portion 111 in a longitudinal direction perpendicular to a general plane on which the top portion 111 lies. The top portion 111 and the annular wall 112 together define an inner space 110 for receiving a metal ring 2 and an annular magnet 3. The top portion 111 includes a shaft base 113 on a center of an inner face thereof and located in the inner space 110. An end of the shaft 13 is coupled with the shaft base 113. The annular wall 112 has a thickness T2 substantially smaller than that T1 of the top portion 111.

With reference to FIGS. 4 and 5, the metal ring 2 of this embodiment is mounted in the inner space 110 of the hub 11 by tight coupling. The annular magnet 3 is inserted into a compartment 20 in the metal ring 2, with an end of the annular magnet 3 abutting against an annular lip 21 extending radially inward from an inner end of the metal ring 2 adjacent to the top portion 11 of the hub 11. Thus, the annular magnet 3 is fixedly positioned in the compartment 20. An outer diameter of the metal ring 2 is preferably slightly larger than an inner diameter of the inner space 110. Since the annular wall 112 of the hub 11 has a thickness T2 substantially smaller than that T1 of the top portion 111, the annular wall 112 provides the metal ring 2 with enhanced plastic deformation capability such that the metal ring 2 can be easily inserted into and positioned in the inner space 110 by tight coupling. After the metal ring 2 has been completely inserted into the inner space 110, the annular wall 112 also provides a resilient restoring force to reliably clamp the metal ring 2 in the inner space 110. Thus, the metal ring 2 encloses the annular magnet 3 to avoid magnetic leakage. Meanwhile, the metal ring 2 presses against the inner periphery of the annular wall 112 to enhance the annular wall 112 whose thickness T2 is substantially smaller than that T1 of the top portion 111 of the hub 11.

Still referring to FIGS. 4 and 5, since the annular wall 112 has a reduced thickness T2 smaller than that T1 of the top portion 111, the overall weight of the annular wall 112 is reduced, and the thickness error of the annular wall 112 during injection molding is also reduced. Uneven weight in the peripheral portion of the hub 11 is avoided, the balancing performance of the impeller 1 is enhanced, and the amount of material required for forming the hub 11 is saved.

FIG. 6 shows an impeller 1 of a second embodiment according to the preferred teachings of the present invention. Compared to the first embodiment, the impeller 1 of the second embodiment further includes at least one positioning portion “a” projecting inward from the inner periphery of the annular wall 112. The positioning portion “a” abuts against an outer end of the metal ring 2 to avoid the metal ring 2 to move out of the inner space 110 of the hub 1. Thus, the assembling reliability of the impeller 1 is enhanced and the life of the impeller 1 is prolonged.

The disadvantages of the conventional impellers are avoided by the impellers 1 according to the preferred teachings of the present invention that include a hub 11 having an annular wall 112 thinner than the top portion 111 of the hub 11 to enhance the plastic deforming capability of the annular wall 112 such that the metal ring 2 can be inserted into the inner space 110 of the annular wall 112 by tight coupling. The manufacturing procedures are simplified, and material costs are cut.

While the principles of this invention have been disclosed in connection with specific embodiments, it should be understood by those skilled in the art that these descriptions are not intended to limit the scope of the invention, and that any modification and variation without departing the spirit of the invention is intended to be covered by the scope of this invention defined only by the appended claims.

Claims

1. An impeller comprising:

a hub including a top portion and an annular wall extending from a circumference of the top portion in a direction perpendicular to the top portion, with the top portion and the annular wall together defining an inner space, and with the top portion including a shaft base adapted for coupling with a shaft located in the inner space;

a plurality of blades mounted to an outer periphery of the annular wall; and

a metal ring mounted in the inner space of the hub, with the annular wall having a thickness substantially smaller than that of the top portion, allowing the metal ring to be inserted into the inner space by tight coupling.

2. The impeller as claimed in claim 1, with the annular wall including at least one positioning portion extending inward from an inner periphery of the annular wall, and with said at least one positioning portion abutting with an outer end of the metal ring distant to the top portion of the hub to retain the metal ring in the inner space.

3. The impeller as claimed in claim 1, with the metal ring including a compartment adapted for receiving an annular magnet.

4. The impeller as claimed in claim 1, with the metal ring including an inner end adjacent to the top portion of the hub, with the metal ring further including an annular lip extending radially inward form the inner end of the metal ring, and with the annular lip being adapted to abut against an end of an annular magnet mounted in the metal ring.