EP0477650B1

EP0477650B1 - Vortex flow blower

Info

Publication number: EP0477650B1
Application number: EP91115274A
Authority: EP
Inventors: Ito Eiichi; Susumu Yamazaki; Masayuki Fujio; Toshiharu Yoshidomi; Hiroshi Asabuki; Kazuo Kobayashi; Kengo Hasegawa; Yukio Chihara; Hajime Fujita
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1990-09-14
Filing date: 1991-09-10
Publication date: 1996-05-29
Anticipated expiration: 2011-09-10
Also published as: KR100190424B1; DE69119854T2; EP0477650A2; KR920006657A; EP0477650A3; DE69119854D1

Description

BACKGROUND OF THE INVENTION

The present invention relates to a vortex flow blower of the kind referred to in the preamble portion of claim 1. Such a vortex flow blower is known from US-A-4 483 656.
Conventional apparatus are constituted such that, as disclosed in Japanese Utility Model Laid-Open Application No. 49-130406, an electric motor is provided in a spaced relationship from a fan casing and a location therebetween is used as a ventilating passageway for enabling windings and bearings of the electric motor to be cooled.
Further, in conventional vortex blowers such as flow pumps, either an impeller or blower casing, a motor casing and a silencer casing are formed as separate parts or a blower casing and a silencer casing are formed as a unitary part while a motor casing is formed as a separate part. Meanwhile, heat radiating ribs on a blower casing and a motor housing are formed intermittently as disclosed in the Official Gazette of Japanese Patent Publication Application No. 57-50952 and the Official Gazette of Japanese Utility Model Laid-Open Application No. 47-26314.
Additionally, a conventional vortex pump has around an inlet port, as disclosed, for example, in Japanese Patent Publication Application No. 46-33658, a construction such that the sectional area in the neighborhood of such inlet port is made greater than the sectional area of an intermediate portion of an annular groove so as to only reduce the resistance of a flow passageway to wind or air.
A conventional vortex flow blower also utilizes a conventional silencer or muffler installed at each of an inlet port and an outlet port and a high pitch sound diffusing porous tube is built in the inside of each of the silencers as disclosed, for example, in the Official Gazette of Japanese Utility Model Laid-Open Application No. 56-109690. Furthermore, another structure is disclosed in the Official Gazette of Japanese Laid-Open Application No. 58-4795 wherein a silencer constituted from a tubular case is provided at an exhaust port of a blower and a tubular silencing material having a heat insulating property is provided on an inner periphery of the case. Also, is it known to frequently use an expansion type silencer and a branch type silencer as silencers for an automobile.
Additionally, a conventional vortex blower utilized as a centrifugal pump includes a silencer or muffler casing having shape equal or similar to a rectangular parallepiped to provide a volume for deadening noise, and with sidewalls rising straight from its base, as shown in Japanese Patent Application Laid-Open No. 52600/1981.
The prior art described above does not pay any attention to reduction in size and mass productivity of the vortex flow blower, and since an electric motor casing and a blower casing are coupled to each other by a coupling arrangement with a spacing left therebetween and with a heat insulating wall is disposed therebetween, there are problems that the dimensions of the vortex flow blower (particularly the dimension along a direction of the shaft of the rotor of the electric motor) are increased, that the number of parts is great, and that the means productivity ability is lowered. Further, since the number of parts is great the number of operation steps in assembly is great such that the quality is not uniform and reliability is low because high accuracy in assembly is not attained.
Additionally, the above-mentioned prior art does not pay any attention to a frictional action acting in the same direction as the direction of rotation of the impeller during impeller rotation, and such prior art has a small capacity for an increase of an amount of fluid or air flowing.
Further, the conventional vortex flow blowers described above have drawbacks that the flow efficiency is not always high and generally have a high noise level. Factors resulting in production of noises by a vortex flow blower include (a) collision noises at an outlet port, (b) collision noises between a whirling flow in a casing flow passageway and a front edge of a vane of the impeller, (c) expansion noises and mixing noises at an inlet port, (d) disorder noises during whirling of a whirling flow, and so forth. Among such factors, the production amount of noise of (a) and (b) is much greater than the production amount of (c) and (d), and in order to reduce noise, it is important to reduce (a) and (b) or reduce noise by a silencer.
If a relative flow w₁ upon flowing into vanes of the impeller is experimentally determined from a flowing-in flow (absolute flow) c₁ of air into the vanes and a vane circumferential speed u₁, then the relative flow w₁ is about 2.5 times the vane circumferential speed u₁ and is a very high flowing speed. Due to such flowing in speed w₁, disorders are produced by flowing-in to front edges of the vanes, and thus lower the efficiency of the vortex flow blower and produces noises. The relationship between noises of a vortex flow blower and an inlet flow rate has such a characteristic that, as the flow rate increases, noises are decreased and the noise level is highest at a point of cut-off. Since a vortex flow blower is used in most cases in a low flow rate region, the noise level at an operating point of the vortex flow blower is high, and, for example, where the power of the shaft of a motor is on the order of 400W, the noise level is about 85 to 95 dB (without a silencer) and is therefore high. Additionally, the noise characteristic in this instance is such that a dominant sound pressure level, like a chimney, is exhibited at a frequency (rotational noise) of [vane number x rotational speed] at which noises of a shrill tone are produced.
In the vortex flow blower disclosed in the Official Gazette of Japanese Utility Model Laid-Open Application No. 56-109690, a silencer is provided at each of the inlet side and the outlet side, and the effect of the silencers is that, where the silencers for both of the inlet side and the outlet side are provided, the noise level is reduced to about 65 to 70 dB, but rotational noises of [vane number x rotational speed] still remain dominantly like a chimney and have a shrill disagreeable tone. Thus, reduction of such rotational noises is desired.
It is known to provide mufflers on an automobile for reduction of noises (pulsating sounds) and pulsation of exhaust gas of an engine and have a function and structure for (a) enabling silencing by use of interference in the muffler, (b) positively adding a ventilation resistance to reduce pulsation, (c) the fact that, since exhaust gas is high in temperature, a porous elastic material (silencing material) cannot be used. Accordingly, where, for example, a silencing material is not used as in the case of (c) described above, a flow of air will flow directly into an expansion chamber to present a high ventilation resistance, and, as a result, a ventilation resistance is high similarly as in the case wherein a ventilation resistance is applied.
Additionally, no consideration has hitherto been given to any measure for facilitating the manual transportation of the vortex flow blower operating as a centrifugal pump, or for enabling a reduction in height of the pump to achieve a smaller overall size. Therefore, the known pump has been difficult to transport, and a reduction of its height results in an increase in width of the silencer casing and therefore an increase in size.
US-A-4 483 656 discloses a vortex flow blower including a blower casing having an annular flow passageway extending from an inlet port for receiving fluid to an outlet port for discharging the fluid, the outlet port being disposed adjacent to the inlet port, an impeller accommodated in the blower casing for producing a vortex flow of the fluid in the annular flow passageway, means for driving the impeller, and enabling means for enabling at least one of a reduction of temperature of the fluid discharged from the vortex flow blower, an increase in at least one of flow rate and pressure of the discharge fluid, a reduction in noise level of the vortex flow blower, and a compact configuration of the vortex flow blower.
It is an object of the present invention to provide a vortex flow blower which is small in size and is readily mass producible.
It is another object of the present invention to provide a vortex flow blower which is superior in aerodynamic performance by lowering the temperature of the fluid discharged by the blower.
According to the present invention the above objects are accomplished with a vortex flow blower as claimed in claim 1.
Dependent claims are directed on features of prefered embodiments.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show for purposes of illustration only, several embodiments in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figs. 1 and 2 are front and rear perspective views, respectively, of a vortex flow blower in accordance with the present invention.
Fig. 3 is a front elevational sectional view showing construction of a vortex flow blower according to an embodiment of the present invention.
Fig. 4 is a sectional view taken along line A-A of Fig. 3.
Fig. 5 is a sectional view taken along line B-B of Fig. 3.
Fig. 6 is a side elevational view of the vortex flow blower of the present embodiment.
Fig. 7 is a diagram showing a temperature upon cut-off operation of the vortex flow blower of the present embodiment.
Fig. 8 is a characteristic diagram showing a shaft power and a temperature with respect to an amount of fluid of the vortex flow blower of the present embodiment.
Fig. 9 is a characteristic diagram showing a difference in aerodynamic characteristic depending upon presence or absence of a cooling ventilating passageway.
Fig. 10 is a front elevational sectional view of a modification of the present embodiment.
Fig. 11 is a side elevational sectional view showing a principal portion of another modification of the present embodiment.
Figs. 12 and 13 are a front elevational sectional view and a side elevational view, respectively, of a further modification to the present embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings wherein like reference numerals are utilized to designate like parts throughout the views, Figs. 1 and 2 are a front and rear perspective view of a vortex flow blower in accordance with the present invention wherein casing 2 of the motor blower includes a blower or impeller casing 3, a motor casing 4, and a silencer or muffler casing 5.
As shown in Fig. 3, which is a cross-sectional view of a vortex flow blower in accordance with an embodiment of the present invention, an electric motor 30 serving as a driver has an impeller 1 of the blower connected to an end of a rotary shaft 14 thereof while a cooling impeller 18 is connected to the other end of the rotary shaft 14. The electric motor 30 includes a rotor 16 fitted on the rotary shaft 14 and a stator 17 fitted in the motor casing 4. The shaft 14 is supported by a radial bearing 14a provided adjacent the impeller 1 and another radial bearing 14b provided adjacent the cooling impeller 18. The impeller 1 is accommodated in the blower casing 3 which is provided with a cover 15.
The blower casing 3 has an annular flow passageway 3a provided in an opposing relationship to vanes of the impeller 1 and extending from an inlet port 3b to an outlet port 3c. When the stator 17 of the electric motor 30 is energized, the rotor 16 mounted on the rotary shaft 14 is rotated, and consequently, the impeller 1 sucks air from the inlet port 3b, pressurizes the air in the annular passageway 3a and discharges the air from the outlet port 3c. The silencer casing 5 for reducing noises is provided for each of the inlet port 3b and outlet port 3c. In the present embodiment, the blower casing 3 is formed in an integral relationship with an electric motor casing 4 and the silencer casing 5 by aluminum diecasting. Meanwhile, in the present embodiment, as shown in Figs. 3 and 4, an axial cooling ventilating passageway or gap 36 is formed between the electric motor casing and the silencer casing 5, and a radial cooling ventilating passageway 34 serving as a radially provided cooling passageway is formed between the inlet port 3b and the outlet port 3c of the blower casing 3 in a contiguous relationship to the cooling ventilating passageway 36 as shown in Fig. 5.
External air 13 is taken into the blower by the cooling impeller or fan 18 and is advanced toward the blower casing 3 through the axial cooling ventilating passageway 36 until it comes to a location in the neighborhood of the bearing 14a adjacent the annular flow passageway, and then it changes the direction and enters the radial cooling ventilating passageway 34, whereafter it passes between the inlet port 3b and the outlet port 3c and is then discharged outside.
Here, thermal income and outgo of the vortex flow blower will be examined. Heat generation is heat the electric motor 30 generates from a portion of the blower, and discharging of heat is dominantly performed by heat transmission by ventilation wherein the cooling fan or impeller 18 and the blower impeller 1 serve as ventilation sources. Heat generation increases continuously as the blower operating condition advances from an open condition to a cut-off condition because the power of the shaft increases continuously. As for the cooling performance, while discharging of heat by the cooling impeller 18 is substantially constant, discharging of heat by air discharged from the blower decreases continuously until it becomes equal to 0 by cut-off. As a result, the temperature rise of the bearing 14a presents, due to an influence of the thermal income and outgo described above, such a curve which rises toward the cut-off as shown in Fig. 8.
In the present embodiment, external air of a lower temperature is caused to flow among the electric motor 30 and the inlet port 3b, outlet port 3c and portions of the silencer casing 5 at which the temperature is raised in communication with the annular flow passageway 3a at which the temperature becomes high due to operation of the blower, in order to reduce the possibility of thermal deterioration of insulating insulators, grease and so forth. Further, as heat energy produced at the blower portion is removed at the location between silencer portions 5 and the inlet port 3b and outlet port 3c, also the temperatures in the annular flow passageway 30 and the impeller 1 are lowered indirectly. Consequently, the specific gravity of the fluid (gas) (air) in the annular flow passageway 3a and the impeller 1 is increased, and energy provided from the impeller 1 is increased. As a result, the blower exhibits an aerodynamic characteristic having a high static pressure. Additionally, as seen from the phase of production technology, it is possible to form the axial cooling ventilating passageway 36 and the radial cooling ventilating passageway 34 as a unitary form in the casing 2, which is advantageous when it is produced as a casting or a molded article (plastic, die-cast and so forth). Characteristics of the vortex flow blower of the present embodiment will be described with reference to Figs. 7 to 9. A surface temperature of the cooling ventilating passageway of the vortex flow blower of the present embodiment and a temperature of air after passing the cooling ventilating passageway were measured at points C and D of Fig. 3, respectively; an outer surface temperature of the blower casing and a temperature of air after passing the outer surface of the blower casing were measured at points E and F of Fig. 6, respectively; and a temperature of the bearing 14a on the blower casing side was measured at a point G of Fig. 3 and curves showing results of such measurements are indicated in Fig. 8. Further, measurement values at the measurement points C, D, E and F upon cut-off operation are indicated in Fig. 7
As shown in Fig. 7, upon cut-off operation, the temperature increase value of air passing the cooling ventilating passageways 36 and 34 is 65°C, and this indicates that it is a cooling capacity about three times per the same flow rate as compared with the temperature increase value 20°C of air flowing along the outer surface of the blower casing 3. This arises from the fact that the temperature at the point C on the surface of the cooling ventilating passageway is remarkably higher than the temperature at the point E on the outer surface of the blower casing and that, while, in the cooling ventilating passageway, exfoliation of ventilation air from the surface of the ventilating passageway is very small, on the outer surface of the fan casing, exfoliation of ventilation air from the outer surface of the casing is present.
As described above, where the cooling ventilating passageway 34 is provided, the present embodiment can obtain a great cooling capacity as compared with the case wherein air is passed only along the outer surface of the blower casing. Due to such difference in cooling capacity, also air in the blower casing 3 and in the impeller 1 is lowered in temperature, and consequently, the specific weight of air is increased. As a result, the air performance can be improved as compared with an apparatus which does not have a cooling ventilating passageway as shown in the curves of Fig. 9.
According-to the present embodiment, as the radial cooling venting passageway 34 passes air, which has passed through the axial cooling ventilating passageway 36, between the outlet port 3c and the inlet port 3b, and which both exhibit a substantially maximum temperature rise a superior cooling performance is obtained, and since a location between the outlet port 3a and the inlet port 3b which is a break of the annular flow passageway 3c is used effectively, the distance in the axial direction can be minimized.
A modification to the present embodiment will be described with reference to Fig. 10, wherein the axial length of the radial cooling ventilating passageway 34 is increased to increase the area over which the cooling air contacts a high temperature portion and thermal isolation between air discharged from the outlet port 3c and air taken in from the inlet port 3b is improved to reduce the temperature increase of intake air to improve the cooling performance.
Another modification to the present embodiment will be described with reference to Fig. 11, wherein a cover portion 5h is provided for the axial ventilating passageway 36 to form an independent duct to increase an air current into the radial ventilating passageway 34 so as to improve the cooling performance.
A further modification to the present embodiment will be described with reference to Figs. 12 and 13, wherein a guide 3d is provided below the blower casing 3 such that cooling air blown out from the radial ventilating passageway 34 is guided by the guide 3j so that it flows along an outer periphery of the blower casing 3 as indicated by a heavy arrow mark in Fig. 13. If the vortex flow blower of the present modification is mounted on a mounting base shown by an alternate long and short dash line in Fig. 12, then air blown out from the radial ventilating passageway 34 collides with the mounting base and changes its direction so that it advances toward the cover 15. A baffle portion 15a is formed on the cover 15 so that such air flow in a straight direction is blocked. Consequently, the air flow changes its direction and flows along the outer periphery of the blower casing 3. Thereupon, exfoliation of the air flow can be restricted by the guide 3d.
As described, the present invention provides a vortex flow blower or centrifugal pump applicable not only to air type but also liquid type which is easy to transport, produces an outstandingly good result of noise deadening, and has both a small height and a small muffler casing width.
While we have shown and described embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art and we therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

Claims

A vortex flow blower including a blower casing (3) having an annular flow passageway (3a) extending from an inlet port (3b) for receiving fluid to an outlet port (3c) for discharging the fluid, the outlet port (3c) being disposed adjacent to the inlet port (3b), an impeller (1) accommodated in the blower casing (3) for producing a vortex flow of the fluid in the annular flow passageway (3a), means (30) for driving the impeller (1), the driving means (30) including an electric motor having the impeller (1) connected to an end of a shaft (14) of a rotor (16) thereof and a cooling impeller (18) connected to another end of the shaft (14) of the rotor (16), and enabling means for enabling at least one of a reduction of temperature of the fluid discharged from the vortex flow blower, an increase in at least one of flow rate and pressure of the discharge fluid, a reduction in noise level of the vortex flow blower, and a compact configuration of the vortex flow blower,
characterized by in that
the enabling means includes means delimiting a cooling passageway (36) disposed between the inlet port (3b) and the outlet port (3c) for cooling at least a surface of a portion of the annular flow passageway (3a) extending between the inlet port (3b) and the outlet port (3c),

the cooling impeller provides cooling air flow through the cooling passageway (36),

means delimiting a ventilating passageway (34) and communicating with the cooling passageway (36), the means delimiting the ventilating passageway being a duct member.
A vortex flow blower according to claim 1, wherein the blower casing includes guide means for guiding cooling fluid along an outer periphery of the blower casing, the cooling passageway (36) enabling fluid discharged therefrom to be guided by the guide means so that the fluid flows along the outer periphery of the blower casing (4).
A vortex flow blower according to claim 1, wherein the blower casing (4) includes a pair of annular flow passageways (3a) disposed on opposite sides of the impeller (1), the impeller having vanes opposed to the pair of annular passageways.