EP1325702B1

EP1325702B1 - Centrifugal blower for vacuum cleaner

Info

Publication number: EP1325702B1
Application number: EP02011834A
Authority: EP
Inventors: Hyeon Sik Nam; Ho Seon Rew; Young Woo Lee
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2002-01-03
Filing date: 2002-05-28
Publication date: 2010-07-14
Anticipated expiration: 2022-05-28
Also published as: EP1325702A3; DE60236993D1; EP1325702A2

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a centrifugal blower for a vacuum cleaner according to the preamble of claim 1. The blower is configured to generate a sucking force in the interior of a body of the vacuum cleaner I and is capable of reducing the flow loss of air sucked into an impeller housing, thereby achieving an improvement in blowing performance.

Description of the Related Art

JP 60-216 097 A discloses a centrifugal blower for an air cleaner comprising an impeller housing, a motor housing connected to the rear end of the impeller housing, a motor provided in the motor housing and a centrifugal impeller received in the impeller housing. The impeller is connected to a driving shaft which in turn is connected to the rotor of the motor. A fixed plate is arranged in the impeller housing closed to the rear side of the impeller facing to the motor housing. Radially outwards of the impeller the fixed plate is provided at its front side with diffuser vanes and at its rear side with guide vanes. An annular rib is projecting from the surface of the fixed plate facing to the rear side of the impeller without contacting the impeller. This annular rib shall restrict the leakage of air into the space between the impeller and the fixed plate.
As well known, a vacuum cleaner is a cleaning appliance using a centrifugal blower adapted to generate a sucking force, thereby removing foreign matters such as dust from sucked air. Recently , active research has been made to develop a centrifugal blower capable of obtaining an improved blowing performance while achieving a reduction of noise.
Fig. 1 is a sectional view illustrating the body of a general vacuum cleaner.
As shown in Fig. I, the general vacuum cleaner includes a body 100, and a sucking mechanism (not shown) connected to a hose 110 fitted in a suction port 102 provided at the body 1001 and adapted to suck foreign matters, such as dust, along with air. A dust collecting bag 120 is received in the body 100. The dust collecting bag 120 filters foreign matters contained in sucked air while allowing the sucked air to pass therethrough, thereby collecting the filtered foreign matters therein. A centrifugal blower 130 is also installed in the body 100 in order to generate a sucking force for sucking foreign matters, along with air, into the interior of the body 100. A discharge port 104 is formed at the rear end of the body 100 in order to outwardly discharge the air passing through the centrifugal blower 130.
A filter 125 is arranged between the dust collecting bag 120 and the centrifugal blower 130 in order to clean air flowing to the centrifugal blower 130. An electric wire 150 is connected to the centrifugal blower 130 in order to supply electric power.
As shown in Figs. 2 and 3, the conventional centrifugal blower used for vacuum cleaners includes an impeller housing 132 provided at a front end thereof with a suction port 132a and opened at a rear end thereof, a centrifugal impeller 134 rotatably installed in the impeller housing 132, diffuser vanes 136 for feeding air discharged from the centrifugal impeller 134 in a pressurized state, guide vanes 138 for guiding air discharged from the diffuser vanes 136 toward the rear end of the impeller housing 132, a motor 140 connected to the centrifugal impeller 134 via a rotating shaft 142 so as to rotate the centrifugal impeller 134, and a motor housing 144 adapted to protect the motor 140.
A fixed plate 148 is installed at the rear of the centrifugal impeller 134 while being spaced apart from the centrifugal impeller 134 to define a gap g therebetween so that it does not come into contact with the centrifugal impeller 134 during rotation of the centrifugal impeller 134. The fixed plate 148 is formed at its central portion with a hole 146a, through which the rotating shaft 142 extends.
The fixed plate 146 is provided at the edge of its front surface with diffuser vanes 136, and at its rear surface with guide vanes 138. The diffuser vanes 136 and guide vanes 138 are integral with the fixed plate 146.
The motor housing 144 has an opened front end connected to the impeller housing 132, while having discharge ports 144a at its rear end in order to outwardly discharge air. A bearing support 148 is arranged between the motor housing 144 and the impeller housing 132.
The bearing support 148 serves to support a bearing 147 adapted to rotatably bear the rotating shaft 142.
Now, the operation of the conventional centrifugal blower having the above mentioned configuration will be described.
Air sucked into the impeller housing 132 sequentially passes through the centrifugal impeller 134, and the diffuser vanes 136, and then enters the interior of the motor housing 144 as it is guided by the guide vanes 138. The air introduced in the motor housing 144 cools the motor 140, and then emerges from the motor 140 through discharge ports 144a of the motor housing 144.
Thus, the centrifugal blower 130 generates a sucking force in accordance with a rotating force of the centrifugal impeller 134. The air sucked by the sucking force cools the motor 140 while passing through the motor housing 144, and emerges from the motor 140.
In the above mentioned conventional centrifugal blower, however, flow loss occurs because the air discharged from the centrifugal impeller 134 is leaked into the gap g defined between the centrifugal impeller 134 and the fixed plate 146, as shown in Fig. 2. Furthermore, the air leaked into the gap g forms a vortex flow R1 rotating about the rotating shaft 142 of the motor 140 in accordance with a centrifugal force generated during the rotation of the centrifugal impeller 134, thereby increasing vibrations occurring at the centrifugal impeller 134.
The air introduced between adjacent ones of the guide vanes 138 is concentrated toward the pressure surfaces 138a of the guide vanes 138. As a result, when air flows along each guide vane 138, it may be separated from the negative pressure surface 138b of the guide vane 138 at the downstream portion of the guide vane 138, thereby forming a vortex flow R3, as shown in Fig. 4. The vortex flow R3 reduces the available flowing space, so that flow loss occurs.
The separation of air is a phenomenon that air flowing along the negative pressure surface 138b of the guide vane 138 while being in contact with the negative pressure surface 138b is separated from the negative pressure surface 138b at a certain point S (Fig. 4) (hereinafter, referred to as a "flow separation point") because the negative pressure surface 138b is maintained at a pressure lower than that of the pressure surface 138a of the guide vane 138 to which pressure is applied in accordance with the air flow. The air separated from the negative pressure surface 138b of the guide vane 138 locally forms a vortex flow R3 starting from the flow separation point S, thereby generating flow loss and noise.
Flow loss is a main factor causing a degradation in the blowing performance of the centrifugal blower and generation of noise.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made in view of the above mentioned problems involved with the related art, and an object of the invention is to provide a centrifugal blower for a vacuum cleaner capable of reducing the flow loss of air sucked into an impeller housing, thereby obtaining an improved blowing performance while achieving a reduction of noise.
In accordance with the present invention, this object is accomplished by providing a centrifugal blower for an air cleaner according to claim 1.
The blower comprises an impeller housing provided with a suction port; a motor housing connected to a rear end of the impeller housing and adapted to receive a motor; a centrifugal impeller received in the impeller housing and connected to the motor by a rotating shaft to rotate within the impeller housing; a fixed plate arranged in the impeller housing while being spaced apart from the centrifugal impeller by a desired gap, the fixed plate being provided at a front surface thereof with diffuser vanes, and at a rear surface thereof with guide vanes; and leakage preventing means for preventing air discharged from the centrifugal impeller into the gap defined between the centrifugal impeller and the fixed plate. According to the invention, the leakage preventing means comprise a plurality of Labyrinth seals spaced apart from one another.
In accordance with the present invention, the centrifugal blower may further comprise guide means arranged between the impeller housing and the guide vanes, and adapted to guide air flowing in a circumferential direction along an inner surface of the impeller housing in accordance with a centrifugal force generated during rotation of the centrifugal impeller so that the air is fed to the guide vanes.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the drawings, in which:

Fig. 1 is a sectional view illustrating the body of a general vacuum cleaner;
Fig. 2 is a sectional view illustrating a conventional centrifugal blower for vacuum cleaners;
Fig. 3 is a cross-sectional view taken along the line A - A of Fig. 2;
Fig. 4 is a diagram illustrating air flows along guide vanes used in the conventional centrifugal blower;
Fig. 5 is a sectional view illustrating a centrifugal blower for air cleaners according to a first embodiment of the present invention;
Fig. 6 is a perspective view illustrating a centrifugal impeller according to the present invention;
Fig. 7 is a sectional view illustrating a leakage preventing means according to another embodiment of the present invention;
Fig. 8 is a sectional view illustrating a centrifugal blower for air cleaners;
Fig. 9 is a cross-sectional view taken along the line B - B of Fig. 9;
Fig. 10 is a sectional view illustrating a guide means according to another embodiment;
Fig. 11 is a sectional view illustrating a centrifugal blower for air cleaners;
Fig. 12 is a cross-sectional view taken along the line C - C of Fig. 10; and
Fig. 13 is a sectional view illustrating a flow separation preventing means according to another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, preferred embodiments of the present invention will be described in detail, with reference to the annexed drawings
Referring to Figs. 5 to 7, a centrifugal blower for air cleaners according to a first embodiment of the present invention is illustrated. As shown in Figs. 5 to 7, the centrifugal blower includes an impeller housing 10 provided at a front end thereof with a suction port 2 and rearwardly opened to discharge air at a rear end thereof, a motor housing 52 connected to the rear end of the impeller housing 10, and adapted to receive a motor 50, a centrifugal impeller 20 received in the impeller housing 10, and connected to the motor 50 by a rotating shaft 54 to rotate within the impeller housing 10, a fixed plate 35 arranged in the impeller housing 10 while being spaced apart from the centrifugal impeller 20 by a desired gap G, and a leakage preventing means for preventing air discharged from the centrifugal impeller 20 into the gap G defined between the centrifugal impeller 20 and the fixed plate 35.
The rotating shaft 54 is rotatably supported by a bearing 37 disposed in the impeller housing 10. The bearing 37 is supported by a bearing support 38 mounted to the front end of the motor housing 52. The bearing support 38 is configured to allow air emerging from the rear end of the impeller housing 10 to enter the interior of the motor housing 52.
The centrifugal impeller 20 includes a front panel 22 centrally formed with a hole 22a communicating with the suction port 2 of the impeller housing 10 to receive air, a rear panel 24 fixedly mounted to the rotating shaft 54 while being spaced apart from the front panel 22 by a desired distance, and blades 26 arranged between the front panel 22 and the rear panel 24, and adapted to guide air introduced through the hole 22a of the front panel 22 toward the circumferential end of the centrifugal impeller 20, and then to outwardly discharge the air from the circumferential end of the centrifugal impeller 20.
The blades 26 are arranged around the rotating shaft 54 while being uniformly spaced apart from one another in a circumferential direction. Each blade 26 has a plurality of protrusions 26a at each of its front and rear ends. The protrusions 26a are fitted, in a caulked fashion, in respective grooves 24a formed at an associated one of the front and rear panels 22 and 24. In Fig. 6, the caulked portions of the impeller 20 are denoted by the reference character C. Thus, the blades 26 are coupled to both the front and rear panels 22 and 24.
As described above, the diffuser vanes 30 are integrally formed with the edge of the front surface of the fixed plate 35 in order to feed air discharged from the centrifugal impeller 20 in a pressurized sate. Also, the guide vanes 40 are integrally formed with the fixed plate 35 in order to guide air discharged from the diffuser vanes 30 toward the rear end of the impeller housing 10. By these diffuser vanes 30 and guide vanes 40, an air flow space is defined.
Meanwhile, the fixed plate 35 is installed in such a fashion that the gap G is defined between the fixed plate 35 and the rear panel 24 in order to prevent the fixed plate 35 from interfering with the caulked portions C of the rear panel 24 during rotation of the centrifugal impeller 20.
The diffuser vanes 30 are radially spaced apart from the circumferential end of the centrifugal impeller 20 by a desired distance so that they do not interfere with the centrifugal impeller 20 during rotation of the centrifugal impeller 20. The diffuser vanes 30 are arranged around the rotating shaft 54 while extending radially. The diffuser vanes 30 feed air discharged from the circumferential end of the centrifugal impeller 20 at high speed, in a pressurized state. That is, the diffuser vanes 30 convert the velocity energy of air into pressure energy.
The guide vanes 40 are arranged around the rotating shaft 54 while being uniformly spaced apart from one another in a circumferential direction. The guide vanes 40 guide air discharged from the diffuser vanes 30 so that the air is fed to the motor housing 52.
The leakage preventing means, which serves to prevent the air discharged from the circumferential end of the centrifugal impeller 20 from being leaked through the gap G due to a pressure difference between the impeller 20 and the diffuser 30, comprises a plurality of Labyrinth seals 60 installed on the front surface of the fixed plate 35 in such a fashion that they are protruded from the front surface of the fixed plate 35, as shown in Fig. 5.
The Labyrinth seals 60 are arranged in such a fashion that they do not overlap with the caulked portions C protruded from the real panel 24, so that they do not interfere with those caulked portions C during rotation of the centrifugal impeller 20. The Labyrinth seals 60 are firmly fitted in grooves 35a formed at the fixed plates 35, respectively.
The Labyrinth seals 60 serve to minimize the gap G defined between the rear panel 24 of the centrifugal impeller 20 and the front surface of the fixed plate 35 at regions where the caulked portions C do not exist, thereby reducing the air leakage space. The air introduced into in the gap G is subjected to flow resistance while passing through narrow gaps defined among the Labyrinth seals 60. Accordingly, air leakage is reduced. Moreover, the amount of air passing through the gap G is small. Therefore, no vortex flow of air is generated during rotation of the centrifugal impeller 20. Thus, it is possible to prevent generation of vibrations.
Fig. 7 illustrates Labyrinth seals according to another embodiment of the present invention. The Labyrinth seals of Fig. 7 denoted by the reference numeral 60' comprise a plurality of protrusions protruded from at the front surface of the fixed plate 35 toward the rear panel 24 of the centrifugal impeller 20.
The embodiments described hereinafter with respect to Figs. 8 to 13 do not form part of the invention but represent background art that is useful for understanding the invention.
Referring to Figs. 8 to 9, a centrifugal blower for air cleaners is illustrated. In Figs. 8 to 9, elements respectively corresponding to those in Figs. 5 to 7 are denoted by the same reference numerals. As shown in Figs. 8 and 9, the centrifugal blower includes an impeller housing 10 provided at a front end thereof with a suction port 2 and rearwardly opened to discharge air at a rear end thereof, a motor housing 52 connected to the rear end of the impeller housing 10, and adapted to receive a motor 50, a centrifugal impeller 20 received in the impeller housing 10, and connected to the motor 50 by a rotating shaft 54 to rotate within the impeller housing 10, and a fixed plate 35 provided at a front surface thereof with diffuser vanes 30 for feeding air discharged from the centrifugal impeller 20 in a pressurized state, and at a rear surface thereof with guide vanes 40 for guiding air discharged from the diffuser vanes 30 toward the rear end of the impeller housing 10.
In particular, a guide means is arranged between the impeller housing 10 and the guide vanes 40. The guide means serves to guide air flowing in a circumferential direction along the inner surface of the impeller housing 10 in accordance with a centrifugal force generated during rotation of the centrifugal impeller 20 so that the air is fed to the guide vanes 40.
The guide means comprises extensions 70 each extending radially outwardly from the tip of an associated one of the guide vanes 40 toward the inner surface of the impeller housing 10 beyond the fixed plate 35.
Extensions 70 circumferentially partition the space defined between the impeller housing 10 and the guide vanes 40. Accordingly, it is possible to prevent air from flowing circumferentially along the inner surface of the impeller housing 10 by the centrifugal force generated during rotation of the centrifugal impeller 10. The air prevented from flowing circumferentially in the impeller housing 10 is guided to the guide vanes 40 in accordance with the guide function of the extensions 70. Accordingly, it is possible to prevent air from being stationary in the impeller housing 10, thereby reducing flow loss.
Fig. 10 illustrates a guide means according to another embodiment. The guide means of Fig. 10 comprises a plurality of guide plates 70' protruded from the inner surface of the impeller housing 10 toward the guide vanes 40. The guide plates 70' are integral with the impeller housing 10.
Similarly to the extensions 70, the guide plates 70' cut off a circumferential flow of air along the inner surface of the impeller housing 10, and guide the cut-off air flow to the guide vanes 40.
Referring to Figs. 11 and 12, a centrifugal blower for air cleaners is illustrated. In Figs. 11 and 12, elements respectively corresponding to those in Figs. 5 to 7 are denoted by the same reference numerals. As shown in Figs. 11 and 12, the centrifugal blower includes an impeller housing 10 provided at a front end thereof with a suction port 2 and rearwardly opened to discharge air at a rear end thereof, a motor housing 52 connected to the rear end of the impeller housing 10, and adapted to receive a motor 50, a centrifugal impeller 20 received in the impeller housing 10, and connected to the motor 50 by a rotating shaft 54 to rotate within the impeller housing 10, a fixed plate 35 provided at a front surface thereof with diffuser vanes 30 for feeding air discharged from the centrifugal impeller 20 in a pressurized state, and at a rear surface thereof with guide vanes 40 for guiding air discharged from the diffuser vanes 30 toward the rear end of the impeller housing 10, and a flow separation preventing means for preventing air flowing along the guide vanes 40 from being separated from the guide vanes 40 at downstream portions of the guide vanes 40, thereby preventing formation of a vortex flow.
The flow separation preventing means comprises a plurality of splitters 80 each arranged between adjacent ones of the guide vanes 40, and adapted to uniformly distribute air flowing between the associated guide vanes 40. Each splitter 80 has a length shorter than that of the guide vanes 40.
Each splitter 80 is centrally arranged between the associated guide vanes 40 while being curved in the counterclockwise direction to have a desired radius of curvature. Each splitter 80 has a leading edge 80a arranged on a circle connected by leading edges 40c of the guide vanes 40.
In accordance with such a structure, each splitter 80 divides an inlet, defined between the associated guide vanes 40 and adapted to receive air discharged from the diffuser vanes 30, into two inlet portions 43a and 43b, so that air flowing between the guide vanes 40 is uniformly distributed at the downstream portions 41 of the guide vanes 40. As a result, the pressure difference between the pressure surface 40a and negative pressure surface 40b of each guide vane 40 is reduced at the downstream portion 41 of the guide vane 40. Thus, there is no flow separation phenomenon.
The pressure surface 40a of each guide vane 40 is a surface to which pressure is applied as air flows along the guide vane 40, whereas the negative pressure surface 40b of the guide vane 40 is a surface opposite to the pressure surface 40a.
The air flow space defined at the inlet portions 43a and 43b of the guide vanes 40 is narrower than the air flow space defined at the downstream portions 41 of the guide vanes 40 by virtue of the splitters 80. As a result, the pressure at the inlet portions 43a and 43b of the guide vanes 40 is higher than the pressure at the downstream portions 41 of the guide vanes 40, thereby causing air to flow effectively.
In Fig. 12, the reference numeral 43c denotes a trailing edge of each guide vane 40, and the reference numeral 80b denotes a trailing edge of each splitter 80.
Fig. 13 illustrates a flow separation preventing means. As shown in Fig. 13, this flow separation preventing means comprises inlet-side guide vanes 92 adapted to receive air discharged from the diffuser vanes (not shown), and outlet-side guide vanes 94 adapted to discharge air emerging from the inlet-side guide vanes 92 into the interior of the motor housing (not shown). The trailing edge 92d of each inlet-side guide vane 92 is circumferentially spaced apart from the leading edges 94c of the outlet-side guide vanes 94 associated therewith.
Although the air discharged from the diffuser vanes is introduced between adjacent ones of the inlet-side guide vanes 92, and then concentrated on the pressure surfaces 92a of those inlet-side guide vanes 92 in accordance with a centrifugal force generated during rotation of the inlet-side guide vanes 92, no flow separation phenomenon occurs because the inlet-side guide vanes 92 have a reduced length in accordance with the configuration of the flow separation preventing means, so that the pressure difference between the pressure surface 92a and negative pressure surface 92b of each inlet-side guide vane 92 is reduced.
In accordance with the above described flow separation preventing means, each outlet-side guide vane 94 receives air at two regions, so that air is uniformly distributed along the outlet-side guide vane. As a result, the pressure difference between the pressure surface 94a and negative pressure surface 94b of each outlet-side guide vane 94 is reduced. Thus, no flow separation phenomenon occurs.
In Fig. 13, the reference numeral 92c denotes a leading edge of each inlet-side guide vane 92, and the reference numeral 94d denotes a trailing edge of each outlet-side guide vane 94.
It is possible to prevent air from being separated from each guide vane at the downstream portion of the guide vane by the flow separation preventing means illustrated in Figs. 11 to 13, thereby preventing formation of a vortex flow. Accordingly, air guided by the guide vane can be effectively introduced into the motor housing without any interference.
As apparent from the above description, the centrifugal blower for air cleaners according to the present invention includes a leakage preventing means installed at the gap defined between the rear panel of the centrifugal impeller and the fixed plate. The leakage preventing means serves to prevent air discharged from the centrifugal impeller from being leaked through the gap. In accordance with the leakage preventing means, there is little or no air leaked through the gap, so that no vortex flow of air is generated in the gap. Accordingly, it is possible to reduce generation of vibrations.
A guide means is provided between the impeller housing and the guide vanes in order to prevent air from flowing along the inner surface of the impeller housing. By the guide means, the air is guided to flow along the guide vanes. Accordingly, there is an advantage in that it is possible to prevent flow loss while preventing generation of vortex flows, thereby preventing generation of vibrations.
The centrifugal blower also includes a flow separation preventing means for preventing air from being separated from each guide vane at a downstream portion of the guide vane. By this flow separation preventing means, it is possible to prevent flow loss at the downstream portion of the guide vane.
Thus, the centrifugal blower for air cleaners according to the present invention can reduce flow loss and vibrations generated in the impeller housing, thereby achieving an improvement in blowing performance while improving the heat discharging performance of the motor, and achieving reduction of noise.
Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope of the invention as disclosed in the accompanying claims.

Claims

A centrifugal blower for an air cleaner comprising:
- an impeller housing (10) provided with a suction port (2) ;

- a motor housing (52) connected to a rear end of the impeller housing (10), and adapted to receive a motor (50) ;

- a centrifugal impeller (20) received in the impeller housing (52), and connected to the motor (50) by a rotating shaft (54) to rotate within the impeller housing (10);

- a fixed plate (35) arranged in the impeller housing (10) while being spaced apart from the centrifugal impeller (20) by a desired gap (G), the fixed plate (35) being provided at a front surface thereof with diffuser vanes (30), and at a rear surface thereof with guide vanes (40); and

- leakage preventing means for preventing air discharged from the centrifugal impeller (20) into the gap (G) defined between the centrifugal impeller (20) and the fixed plate (35),
characterized in that
- the leakage preventing means comprise a plurality of Labyrinth seals (60, 60') spaced apart from one another.
The centrifugal blower according to claim 1, wherein the Labyrinth seals (60) are firmly fitted in grooves (35a) formed at the front surface of the fixed plate (35).
The centrifugal blower according to claim 1, wherein the Labyrinth seals (60') are protrusions formed at the fixed plate (35) while being integral with the fixed plate (35).
The centrifugal blower according to claim 1, wherein the Labyrinth seals (60, 60') are uniformly spaced apart from one another.
The centrifugal blower according to claim 1, wherein:
- the centrifugal impeller (20) comprises a front panel (22), a rear panel (24) spaced apart from the front panel (22), and a plurality of blades (26) arranged between the front and rear panels while being caulked to the front and rear panels; and

- each of the Labyrinth seals (60, 60') is arranged not to overlap with the caulked portion of each of the blades protruded from the rear panel (24), so that it does not interfere with the caulked portion.
The centrifugal blower according to claim 1, further comprising:
guide means arranged between the impeller housing (10) and the guide vanes (40), and adapted to guide air flowing in a circumferential direction along an inner surface of the impeller housing (10) in accordance with a centrifugal force generated during rotation of the centrifugal impeller (20) so that the air is fed to the guide vanes (40).