US3844674A

US3844674A - Vortex blower

Info

Publication number: US3844674A
Application number: US00387511A
Authority: US
Inventors: K Moriyama
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1972-09-06
Filing date: 1973-08-08
Publication date: 1974-10-29
Anticipated expiration: 1991-10-29
Also published as: JPS4945413A; DE2342245B2; DE2342245A1

Abstract

A vortex blower of the type adapted to be directly connected to an electric motor, comprising a casing formed with an air passage therein, a stator with stator windings securedly mounted in the casing, a shaft fixed to the casing, an impeller rotatably supported by the shaft and provided with a plurality of blades juxtaposed to the air passage, and a rotor securedly mounted, in the impeller and juxtaposed to the driving part of the stator. The vortex blower is constructed such that there is no gap to be accurately set during the assembling thereof other than one predetermined gap defined between the casing and the impeller.

Description

United States Patent 1191 Moriyama Oct. 29, 1974 VORTEX BLOWER 3,601,507 8/1971 Harris 415 213 T [75] Inventor: Jl(a2;)z;1nyosh1 Morlyama, l-l1tach1, mary Examiner carlton R- Croyle Assistant ExaminerL0uis J. Casaregda Assigneei Hitachi, y J pa Attorney, Agent, or Firm-Craig & Antonelli [22] Filed: Aug. 8, 1973 2 A l N 387 511 [57] ABSTRACT 1] A vortex blower of the type adapted to be directly connected to an electric motor, comprising a casing [30] Foreign Application Priority Data formed with an air passage therein, a stator with stator Sept. 6, 1972 Japan 47-88716 windings Securedly mounted in the Casing, a Shaft fixed to the casing, an impeller rotatably supported by [52] US. Cl. 415/53 T, 415/213 T, 417/352 the shaft and provided with a plurality of blades juxta- [51] Int. Cl. F040 5/00, F04b 17/00, F04b 35/00 posed to the air p ag and a rotor s d y 58 Field of Search 417/352, 353, 420; mounted, in h impeller and juxtaposed to the drivmg 415 53 1213 T part of the stator. The vortex blower is constructed such that there is no gap to be accurately set during [56] References Cited the assembling thereof other than one predetermined UNITED STATES PATENTS gap defined between the casing and the impeller. 3,337,122 8/1967 Gross 310/268 10 Claims, 4 Drawing Figures I08 I12 09 III\;. 102 5 H7 PAIENTEDum 29 I974 3,844,674

SHEET 10F 2 FIG.

PRIOR ART FI'G.2

PAIENTED 0m 29 I974 SHEET 2 BF 2 FIG.3

FIG. 4

VORTEX BLOWER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vortex blower, and more particularly to a vortex blower of the type adapted to directly connected to an electric motor.

2. Description of the Prior Art A vortex blower of the prior art comprises a casing formed with an air passage therein, a housing disposed axially outwardly of the casing, and an impeller juxtaposed to the casing. The housing is provided therein with various elements of an electric motor including a stator, a rotor concentrically disposed within the stator, a rotor conductor mounted on the outer periphery of the rotor, and a rotary shaft connecting the rotor to the impeller.

In this type of vortex blower, it is necessary to provide, when the vortex blower is assembled, not only a gap of a predetermined dimension between the fan casing and the impeller but also another gap of a predetermined dimension between the outer peripheral surface of the rotor and the inner peripheral surface of the stator in order to increase the operation efficiency of the blower. In this case, difficulty has hitherto been experienced in simultaneously providing these two gaps with a high degree of precision. This has made the process of assembling the blower complex and increased the number of operation steps. As a result, there occurs disadvantages that production cost becomes high and that the frequency of the occurrence of defective products becomes large.

Since the conventional blower uses an electric motor of the cylindrical type, the rotor and impeller connected thereto through a bearing axially shift by a distance corresponding to the play of said bearing, so that a gap of relatively large dimension is caused between the impeller and the casing. This has resulted the lowering of the efficiency of the blower in operation.

In the conventional vortex blower of the type described, variations in load imposed on said blower may result in the axial shifting of the impeller, thereby setting the blower into abnormal oscillations (resonance). The construction of said conventional blower is such that it is impossible to avoid the abnormal oscillation completely. Besides, the conventional vortex blower of the type described has a comparatively great overall dimensions, and this has set limits to the use to which the blower is put.

SUMMARY OF THE INVENTION This invention obviates the aforementioned disadvantages of the prior art. Accordingly, an object of the invention is to provide a vortex blower superior in performance and high in efficiency, wherein there is only provided a gap between the impeller and the casing which need be formed with a high degree of precision when the blower is assembled, said gap being smaller in dimension than the corresponding gap formed in the conventional blower above-mentioned.

Another object of the present invention is to provide a vortex blower adapted to use an electric motor of a flat type in place of an electric motor of the cylindrical type hitherto used with vortex blowers of the prior art, thereby eleminating axial playof the rotor and the impeller.

Still another object is to provide a vortex blower which precludes the occurrence of abnormal oscillations by using an electric motor of the flat type.

Another object is to provide a vortex blower which permits excellent results to be achieved in cooling the electric motor connected to the blower thereby to increase the output power of the motor by mounting the heat generating portion of the motor in close proximity to the blower, said vortex blower being made to have an overall compact size thereof in a case where the output power of the motor is constant.

Another object is to provide a vortex blower which permits the production cost thereof to be reduced by virtue of the fact that the manufacturing processes involved in assembling the blower is less in number than the processes involved in assembling the conventional blower.

A further object is to provide a vortex blower which has been greatly reduced in overall dimensions so that the blower can serve for purposes which have not been envisioned as regards the conventional vortex blower.

Additional and other object as well as features and advantages of the invention set forth hereinafter when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of a vortex blower of the prior art;

FIG. 2 is a vertical sectional side view of a vortex blower embodying the present invention;

FIG. 3 is a front view of the fixed portion of the vortex blower shown in FIG. 2, with the cover and the rotary portion of the blower being removed; and

FIG. 4 is a front view of the rotary portion of the blower shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT A vortex blower of the prior art will at first be described with reference to FIG. 1, wherein 1 indicates the stator of a cylindrical type of electric motor, 2 being a stator winding wound on the stator, 3 being a housing, 4 being a rotor having a rotor conductor 5 secured on the outer periphery of said rotor, said rotor conductor 5 is generally made of aluminum by diecasting, 6 being an end bracket, 7 being a bearing fixed to a fan casing 8 serving as another end bracket, 9 being a guide passage formed in an outer marginal portion of the fan casing, 11 being an impeller juxtaposed to the fan casing and driven by the electric motor M, said impeller 11 being provided with blades l2, 13 being a cover provided on the front surface of the casing, 14 being a suction port formed in a part of the guide passage, a partition plate (not shown) being provided between the suction port 14 and an outlet port (not shown in the figure since it is formed behindthe suction port) so that the blower may function as a pump, and 15 being a rotary shaft supporting the rotor 4 and mounting the impeller on its front end.

In said prior vortex blower, ascan be clearly seen in FIG. 1, there are two gap portions the dimension of which must be maintained at high accuracy with sever tolerances in view of its structure, one (g-l) of said gaps being of between the inner surface of the stator l and the outer peripheral surface of the rotor 4 and being set at 0.3 millimeters in dimension as is the case with ordinary electric motor. The gap g-l) has a significant influence on the characteristics of motors. It has hitherto been customary to maintain the dimension of the gap 3-1 at a predetermined degree of accuracy of machining either the outer periphery of the rotor 4 or the inner surface of the stator 1 (usually the latter) to a high degree of precision. Another gap (g-Z) is of between the fan casing 8 and the impeller 11, said gap g-2 being preferably in a range from 0.3 to 0.4 millimeters in dimension or substantially equal to the gap g-l in the motor so that the characteristics of the blower can be improved. To maintain the dimensions of said two gaps g-l and 3-2 both at a desired level of accuracy in assembling the blower poses a problem difficult to obviate. More specifically, since the rotary shaft of the motor M is connected to the impeller, the accuracy of the dimension of the gap g-2 will tend to be lowered thereby to cause a reduction in the efficiency of the blower, if an attempt is made to improve the characteristics of motor M by maintaining the dimension of said gap g-l at a high level accuracy, and vice versa. This has often made it necessary to disassemble the products to remedy the defect or discard the products as defective products.

A vortex blower embodying the present invention is now described with reference to FIGS. 2, 3 and 4, wherein 101 designates a stator which is a constituting element of a flat type of electric motor and has a stator winding 102 wound thereon, 108 being a fan casing provided around the outside marginal portion thereof with an annular air passage 109 semicircularly arcuate in cross-section. An annular groove 117 adjacent to the air passage 109 is formed in said casing radially inwardly thereof, in which annular groove 117 a stator having the stator winding 102 thereon is securedly mounted. The air passage 109 is closed at one position by a partition 110, on one side of said partition 110 a suction port 114 being formed and an outlet port 114-a being formed on the other side of the partition. Secured to the central portion of the fan casing 108 is a shaft 115, one part of which extends axially outwardly of the casing 108.

111 designates a rotary impeller, wherein a plurality of radial blades 112 of small thickness formed integrally with the impeller are circumferentially disposed in an annular groove formed around the outside marginal portion of the impeller at regular intervals. Each pair of adjacent two blades 112 defines therebetween a compartment 116 substantially similar in crosssection to the air passage 109, a sequence of small compartments being, when assembled, spaced from and in face-to-face relationship with the air passage 109. The smaller the thickness of the blades 112, the higher becomes the operation efficiency of the blower. Thus, the impeller is preferably made of aluminum integrally with the impeller by die casting in order to ensure that dimensional accuracy is readily obtained in the blade of small thickness.

104 designates a rotor iron core formed in annular shape which is embedded, at the same time when the impeller is formed by die casting, into a radially inward part of the rotary impeller 111 in such a manner that said rotor iron core 104 is spaced from and in face-toface relationship with the stator 101 when the blower is assembled. 105 designates a rotor conductor formed integrally with the rotary impeller 111 at the time the impeller is formed by die-casting.

The rotary impeller 111 is rotatably mounted at its central portion through a bearing 107 on one end of the shaft extending axially outwardly of the fan casing 108. 113 designates a blower cover for covering the rotary impeller 111, said blower cover being secured airtightly to an outer edge of the casing by conventional suitable means.

It will be appreciated from the foregoing description that the vortex blower embodying the present invention has only one gap (g) formed between an axially terminal surface of the impeller 111 and an axially terminal surface of the fan casing adjacent to the impeller. Said gap (g) preferably has a dimension within a range from 0.3 to 0.4 millimeter.

In operation, the air in the small compartments 116 provided in the rotary impeller 111 formed integrally with the rotor is forced to move outwardly to the outer marginal portions of the compartment by centrifugal forces when the rotor rotates under the influences of the electromagnetic force caused by the interrelation of the rotor and the stator. The compartments 116 and the air passage 109 formed in the fan casing 108 both are semicircularly curved in cross-section, and the openings of said compartments are opposed to the opening of said air passage so that they may form a substantially circular cross-section. Because of such construction, the air in one compartment 116 is introduced into the adjacent compartment after passing through the air passage. Thus, since the air introduced through the suction port 114 into the air passage 109 is accelerated by the compartments formed in the impeller, the pressure of air in the vortex blower becomes very large before reaching the outlet port 114-1. As a result, the air is jetted from the outlet port 114-1 under a pressure which is nearly ten times as high as the pressure of air discharged in the case of the conventional centrifugal vortex blower. The partition 110 provided in the air passage 109 is intended to prevent leakage of air under pressure from the outlet side to the suction side due to large pressure differences.

The vortex blower constructed as aforementioned according to the invention offers advantages which are summarized as follows:

a. The blower has an overall length which is about one third that of conventional vortex blower. This permits the blower to have application in industrial sewing machine, copying apparatus or the like which have not been envisioned for blowers of the prior art,

b. The fan casing and the rotary impeller are formed integrally with each other, so that the production steps are less than one half in number than those of conventional vortex blowers and the cost of the blower can be reduced accordingly. Besides, since the blower of this invention has a very small number of parts which must be machined with high degree of precision, the quality of the products becomes in a high constant level;

c. In conventional vortex blowers using a cylindrical electric motor, the impeller tends to be subjected to axial forces due to the pressure of air passing through the air passage in operation, and consequently the impeller and rotor tends to shift axially a distance corresponding to a play of the bearing. Because of this, it has hitherto been customary to provide a gap of a relatively large dimension between the impeller and casing by taking into consideration the play of the bearing. In addition, a variation in the load tends to results in axial shifting of the impeller which often causes abnormal oscillations in the blower. These disadvantages of the prior art are obviated by the present invention. The use of an electric motor of the flat type eliminates the need to take into consideration the play or clearance in the bearing in assembling the blower, because the rotary impeller is attracted to the fan casing by a force greater in magnitude than the pressure produced by air moving through the air passage in operation. Thus, the gap g between the impeller and the casing can be made small in dimension, so that the characteristics of the blower are improved and the abnormal oscillation can be preeluded; and

d. In the blower according to the invention, the heat generating portions of the electric motor is disposed in the vicinity of the air passage. This facilitates cooling of the motor and increases its output power, thereby enabling to obtain an overall compact size in a motor provided that the output power is constant.

From the foregoing description, it will be appreciated that the vortex blower of the present invention has only one gap which needs to be provided with a high degree of precesion, the efficiency of said blower being improved, and an overall compact size being obtained.

What I claim is:

l. A vortex blower comprising: a casing, an air passage means formed in the periphery of said casing, inlet and outlet means provided at opposite ends of said passage means, a shaft secured to said casing at the central portion thereof, an impeller having an annular groove provided in the periphery thereof, said annular groove being divided into a plurality of compartments by a plurality of spaced radially extending blades, said impeller being disposed on said shaft with said annular groove being opposed to said air passage means, said impeller being spaced from said casing to form a constant predetermined gap between said annular groove and said air passage means. and means for driving said impeller including a stator means disposed in said casing, a rotor securedly mounted within said impeller, one of said stator means and said rotor means being provided with a means for generating a magnetic force, said rotor means being opposed to and spaced from said stator means to form a gap for accommodating magnetic force transfer between said stator means and said rotor means, said last-mentioned gap and said gap between said annular groove and said air passage means being disposed in a plane transverse to the axis of said shaft.

2. A vortex blower according to claim 1, wherein said gap between said annular groove and said air passage means is of a dimension in a range of 0.3 to 0.4 millimeters.

3. A vortex blower according to claim 1, wherein said air passage is annular in shape, and an annular groove is formed in said casing concentrically with and adjacent said annular air passage in an axially inward part of said casing, said stator means being securedly mounted in said last-mentioned annular groove.

4. A vortex blower according to claim 3, wherein said annular air passage means is semi-circular in crosssection, and wherein said inlet means includes an air inlet port formed at one end portion of said air passage means and said outlet means includes an air outlet port formed at the other end thereof.

5. A vortex blower according to claim 1, wherein said plurality of compartments are formed around an outer marginal portion of said impeller, said compartments being substantially similar in cross-section to the air passage means and being in face-to-face relation with said air passage means.

6. A vortex blower according to claim 5, wherein an iron core is embedded in a radially inward part of said impeller and disposed adjacent the plurality of compartments, and a rotor conductor is formed on said iron rotor core integrally with said impeller.

7. A vortex blower according to claim 1, wherein said gap for accommodating magnetic force transfer and said gap between said annular groove and said air passage means are disposed in a common plane extending transversly to the axis of said shaft.

8. A vortex blower according to claim 1, wherein said gap for accommodating magnetic force transfer and said gap between said annular groove and said air passage means are disposed in a common plane extending perpendicular to the axis of said shaft.

9. A vortex blower according to claim 1, wherein said stator means includes an annular stator core and a stator winding coaxially disposed within said casing with respect to said shaft, and wherein said rotor means includes an iron rotor core and a rotor conductor disposed within said impeller coaxial with respect to said shaft.

10. A vortex blower according to claim 9, wherein said gap for accommodating magnetic force transfer and said gap between said annular groove and said air passage means are disposed in a common plane extending perpendicular to the axis of said shaft.

Claims

1. A vortex blower comprising: a casing, an air passage means formed in the periphery of said casing, inlet and outlet means provided at opposite ends of said passage means, a shaft secured to said casing at the central portion thereof, an impeller having an annular groove provided in the periphery thereof, said annular groove being divided into a plurality of compartments by a plurality of spaced radially extending blades, said impeller being disposed on said shaft with said annular groove being opposed to said air passage means, said impeller being spaced from said casing to form a constant predetermined gap between said annular groove and said air passage means, and means for driving said impeller including a stator means disposed in said casing, a rotor securedly mounted within said impeller, one of said stator means and said rotor means being provided with a means for generating a magnetic force, said rotor means being opposed to and spaced from said stator means to form a gap for accommodating magnetic force transfer between said stator means and said rotor means, said last-mentioned gap and said gap between said annular groove and said air passage means being disposed in a plane transverse to the axis of said shaft.

4. A vortex blower according to claim 3, wherein said annular air passage means is semi-circular in cross-section, and wherein said inlet means includes an air inlet port formed at one end portion of said air passage means and said outlet means includes an air outlet port formed at the other end thereof.