Fluid reaction surfaces (i.e. – impellers) – Unsymmetrical impeller or dissimilar working members
Reexamination Certificate
2000-12-21
2003-07-15
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Unsymmetrical impeller or dissimilar working members
Reexamination Certificate
active
06592329
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electric blower and a vacuum cleaner using the electric blower.
BACKGROUND OF THE INVENTION
A conventional electric blower is described with reference to FIG.
46
.
Impeller
1
comprises rear shroud
2
, front shroud
3
which faces the rear shroud
2
, and a plurality of blades
4
disposed between the pair of shrouds
2
,
3
. Inducer part
5
defines an extending part on inlet hole
13
side of blades
4
and a three-dimensional-shaped curved surface, while the outer periphery of blade
4
has a two-dimensional-shaped curved surface. Electric motor
6
drives impeller
1
. Air guide
7
having a plurality of stationary blades
8
defines a volute chamber between adjacent stationary blades
8
. Fan case
10
includes impeller
1
and air guide
7
, is airtightly mounted to the outer periphery of electric motor
6
, and has an intake opening
11
in its central part.
An operation in this structure is described. When impeller
1
is rotated by electric motor
6
at a high speed, air flow is sucked from inlet hole
13
of impeller
1
, travels through blades
4
without being disturbed by inducer part
5
, and is exhausted from the outer periphery of impeller
1
. The air flow axially comes into inlet hole
13
, but goes out from an outlet of impeller
1
in the centrifugal direction, namely orthogonally to the axial direction. The direction of the air flow changes along the three-dimensional-shaped curved surface of inducer part
5
. The air flow further travels through the volute chamber formed from the plurality of stationary blades
8
mounted to air guide
7
, and goes into electric motor
6
.
As problems of this conventional electric blower, it is difficult to manufacture and has poor productivity because blades
4
include complex-shaped inducer part
5
having the three-dimensional-shaped curved surface. When the blades
4
are manufactured in a cutting work, a very long working time is required, and even when it is manufactured in a molding work, a special manufacturing method is required which makes the blades expensive. A method in which blades
4
are assembled separately from inducer part
5
is also proposed, but there are many requirements, such as easy manufacturing of inducer
5
, joining of inducer
5
to blades
4
so that there is less air leakage and without causing air resistance, and fixing of the inducer
5
that it withstands high speed rotation and does not cause any air leakage between both shrouds
2
,
3
and the inducer
5
. Therefore, this method has not yet commercialized.
DISCLOSURE OF THE INVENTION
The present invention addresses the problems discussed above and aims to provide an electric blower. In this electric blower, a blade of an impeller is divided as a two-dimensional curved-surface-shaped blade and a three-dimensional curved-surface-shaped inducer, and they are constituted as separate components. In addition, problems of strength, clearance, and air resistance are solved, the manufacturing method is simple, and loss is reduced.
For solving the problems discussed above, the electric blower in accordance with the present invention and a vacuum cleaner using it include an electric motor having a rotating shaft and an impeller fixed to the rotating shaft for rotation. The impeller comprises the following elements:
a rear shroud fixed to the rotating shaft;
a front shroud that faces the rear shroud and has an inlet hole to take in air;
a plurality of blades disposed between the rear shroud and the front shroud; and
an inducer which streamlines air flowing from the inlet hole and has a three-dimensional-shaped vane.
The inducer is formed separately from the blade. Thus, a practical electric blower that is simple in structure, least in clearance between parts, higher in strength, lower in loss is realized. An efficient vacuum cleaner high in sucking capacity is realized by the utilization of the electric blower.
A first embodiment of the present invention is an electric blower comprising an electric motor having a rotating shaft and an impeller fixed to the rotating shaft for rotation. The impeller comprises the following elements:
a rear shroud fixed to the rotating shaft;
a front shroud that faces the rear shroud and has an inlet hole to take in air;
a plurality of blades disposed between the rear shroud and the front shroud; and
an inducer which streamlines air flowing from the inlet hole and has a three-dimensional-shaped vane. The inducer is formed separately from the blade and is placed between the rear shroud and the front shroud. The impeller that includes the inducer having a complex shape and has no problem in strength is realized in a simple and mass-producible method. As a result, a downsized, powerful, and highly efficient electric blower can be provided in a lower price.
A second embodiment of the present invention is an electric blower according to the first embodiment, wherein a rear shroud and a front shroud are respectively formed from sheet metals, and an inducer is formed from a moldable material. The high-performance electric blower can be realized in a lower price similar to the first embodiment, by forming the inducer in a resin molding and constituting blades and shrouds with sheet metals.
A third embodiment of the present invention is an electric blower according to the second embodiment, wherein an inducer is molded using a plurality of divided dies that slide substantially radially. The resin made inducer has a shape such that it can be manufactured with slide dies, and therefore, the electric blower having higher mass-productivity can be realized.
A fourth embodiment of the present invention is an electric blower according to the second embodiment or the third embodiment, wherein a number of vanes and a number of the blades are respectively equal to six. The highest efficient condition is selected, and therefore, the highly efficient electric blower having higher mass-productivity can be realized.
A fifth embodiment of the present invention is an electric blower according to the third embodiment, wherein the direction of a line between a point at the tip of a vane of an inducer and a point moved by a clearance from the end of the outer periphery of the vane is matched to a sliding direction of a die. The resin made inducer can be molded in a simple die structure, and the highly efficient electric blower having higher mass-productivity can be realized.
A sixth embodiment of the present invention is an electric blower according to one of the second embodiment to the fifth embodiment, wherein an inducer comprises a substantially conical hub and a plurality of vanes that are fixed to the outer periphery of the hub and have a three-dimensional-shaped curved surface. Furthermore, a parting line generated during molding is formed so that the upstream side of air flow is higher and the downstream side is lower. The electric blower in which resistance of air flow is reduced and efficiency is higher can be realized since the parting line of the inducer that is generated during molding has a step where the upstream side of air flow is higher and the downstream side is lower.
A seventh embodiment of the present invention is an electric blower according to one of the second embodiment to the sixth embodiment, wherein a connecting portion for connecting with the end of a blade is placed at the blade-side end of an inducer. The connecting portion is placed on the inducer for connecting a vane of the resin-made inducer with the blade formed from a sheet metal, leakage of air flow from a joint portion is reduced, and the highly efficient electric blower can be realized.
An eighth embodiment of the present invention is an electric blower according to the seventh embodiment, wherein a recessed part for receiving an end of the blade is drilled in a connecting portion. The electric blower in which leakage is further reduced and an impeller is easily assembled can be realized since the connecting portion of an inducer has a recessed shape.
A ninth embodiment of the present inv
Hirose Toru
Kayama Hiroyuki
Morishita Kazuhisa
Murata Yoshitaka
Nishimura Tsuyoshi
Kershteyn Igor
Wenderoth , Lind & Ponack, L.L.P.
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