US3366316A

US3366316A - Vacuum cleaner having a divergent diffuser

Info

Publication number: US3366316A
Application number: US614934A
Authority: US
Inventors: Frank K Bayless
Original assignee: Electrolux Corp
Current assignee: Electrolux Corp
Priority date: 1965-04-28
Filing date: 1967-02-09
Publication date: 1968-01-30
Anticipated expiration: 1985-01-30

Description

Jan. 30, 1968 F. K. BAYLESS VACUUM CLEANER HAVING A DIVERGENT DIFFUSER 4 Sheets-Sheet 1 Filed Feb. 9, 1967 INVENTOR. FRANK K. BAYLESS W HIS ATTORNEYS Jan. 30, 1968 F. K. BAYLESS VACUUM CLEANER HAVING A DIVERGENT DIFFUSER 4 Sheets-Sheet 2 Filed Feb. 9, 1967 FIG. 4

FIG. 2

INVENTOR. FRANK K. BAY LESS I%W M I HIS ATTORNEYS Jan. 30, 1968 F. K. BAYLESS VACUUM CLEANER HAVING A DIVEHGENT DIFFUSER 4 Sheets-Sheet s Filed Feb.

INVENTOR. FRANK K. BAY LESS ms ATTORNEYS Jan. 30, 1968 F. K. BAYLESS VACUUM CLEANER HAVING A DIVERG ENT DIFFUSER 4 Sheets-Sheet 4 Filed Feb. 9, 1967 INVENTOR.

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S 5 s W a E L N Yaw R A O B A K N A E /M H Y A wL E F 0 n N mu. N U N R W M 0 M LFI FOT United States Patent O 3,366,316 VACUUM CLEANER HAVING A DIVERGENT DIFFUSER Frank K. Bayless, Darien, Conn., assignor to Electrolux Corporation, Old Greenwich, Conn., a corporation of Delaware Continuation-impart of application Ser. No. 451,535, Apr. 28, 1965. This application Feb. 9, 1967, Ser. No. 614,934

4 Claims. (Cl. 230-117) ABSTRACT OF THE DISCLOSURE In a vacuum cleaner airflow is provided by a motor-fan unit within the body of the cleaner. The air being discharged from the motor-fan unit is directed into an annular diverging space defined by wall members which surround the last stage of the blower. The air from the blower is introduced into the diffuser space at its smaller cross-section and is discharged from the enlarged end of the diffuser for increased fan efliciency or increased airflow and suction.

Related application This application is a continuation-in-part of copending application Ser. No. 451,535 by the inventor hereof, now Patent No. 3,303,996 dated Feb. 14, 1967.

Background of the invention Vacuum Cleaners having motor-fan units are known and with a given unit a certain airflow or suction is produced. This invention relates to the discovery that the airflow or suction of a given motor-fan unit is increased by a diverging diffuser.

Air diffusers are known in the prior art in connection with compressors such as disclosed in British Patent 701,560 of Dec. 30, 1953. In this patent primary and secondary diffusers are used in series to reduce the overall frontal area of the compressor. However, no prior art is known in which a diverging diffuser in combination with a motor-fan unit in a vacuum cleaner is used for increasing suction, or negative pressure in a vacuum cleaner.

Summary of the invention The primary object of the invention is to improve the cleaning performance of a vacuum cleaner by the use of a diverging diffuser.

Another object of the invention is to improve the cleaning performance of a vacuum cleaner by an economical and simple change in construction of the cleaner.

Brief description of drawing FIG. 1 is a longitudinal, cross-section, showing a reverse-flow motor-fan unit situated in the tank unit of a vacuum cleaner and incorporating one embodiment of the diffuser according to my invention;

FIG. 2 is a somewhat partial section of FIG. 1 showing my diffuser in greater detail;

FIG. 3 is a somewhat diagrammatic view of my diffuser showing various geometrical relationships thereof and a somewhat idealized representation of the airflow therethrough.

FIG. 4 is a diagrammatic view similar to FIG. 3 but showing a section of my diffuser as being straight, rather than arcuate, so that the various geometrical relationships thereof and the idealized airflow representation may be more clearly shown for purposes of explanation;

FIG. 5 is a partial longitudinal cross-section similar to that shown in FIG. 1, but showing an embodiment of my diffuser incorporated in a commercial vacuum cleaner having a separately cooled motor so that it can be used for picking up water;

FIG. 6 is a partial cross-section view as viewed along the line 66 in FIG. 5;

FIG. 7 is a graphical representation showing the air performance of a reverse-flow motor-fan unit having a diffuser according to my invention; and

FIG. 8 is another graphical representation showing the electrical performance of the reverse-flow motor-fan unit having a diffuser according to my invention.

Description 0 preferred embodiments In FIG. 1 a motor-fan unit having a diffuser according to the first embodiment of my invention is shown mounted within a tank 10 of a tank-type or canister-type vacuum cleaner, the unit being of the reverse fiow type. A dust bag compartment 12 having a plurality of holes 13 therethrough is also mounted within the tank 10 and a dust bag 14 is situated in the compartment 12.

The motor-fan unit is comprised of an electric motor 16 and a centrifugal fan 18 which is driven by the motor. The motor and fan are located downstream of the dust bag 14 so that filtered airstreams, indicated by the arrows A, emanating from the dust bag can pass over the motor 16 to cool it before the airstreams enter the fan 18.

The motor 16 may be a conventional series wound universal motor including a wound armature 20 on an armature shaft 21 which is journaled for rotation in the two bearing members 22 and 23. Surrounding the armature 20 is a laminated stator 19 which includes two opposing pole pieces 24. A field winding 25 encompasses each pole piece 24. One end of the armature shaft 21 is provided with a commutator 26 which is electrically energized through a pair of carbon brush units 17. The motor 16 also includes two

stationary support frames

27 and 28 which. when coupled together by means of bolts 29 support the stator 19 and armature 20. The support frame 27 includes ribs 30 between which there are defined openings so that the airstreams A can pass over the various parts of the motor to cool it. As indicated, the airstreams A pass over the armature 20, stator 19 and field winding 25. In addition, the support frame 27 serves as a support for the bearing member 23 and for the brush units 17. The support member 28 has a cup-like housing and is open at one end, the other end thereof being partly closed and carries the bearing member 22. At the partly closed end of the support frame 28 there is formed a number of radial spokes 31, or rib members and between these adjacent spokes 31 openings are provided so that airstreams A can pass through, as indicated in FIG. 1, into the fan unit 18.

Support frames

27 and 28 may be fashioned from aluminum or the like; for example, cast aluminum is one of a number of materials which are suitable.

Fastened by means of rivets 32 to the outside surface of support frame 28 at the partly closed end thereof is a stationary cup-like housing 33 which may also be fashioned from aluminum. At one end of this housing 33 there is formed an outwardly turned annular flange 34 and in about three or four places on this flange there are provided large diameter holes 35, through which bolts 36, pass for the purpose of securing the housing 33 to a bulkhead 37, which bulkhead is secured to the inside surface of the tank 10, as by welding. An annular rubber gasket 38 is also provided to help secure these aforementioned members together so that vibrations may be damped. In the center of the partly closed end of the ing race 39. Secured to the support frame 28 by means of screws (not shown) are the two centrally apertured sta tionary bearing shields 42 and 43. As shoWn the diameter of the central aperture of these shields 42 and 43 is sufficiently large so that the shields will not interfere with rotation of the armature shaft 21 or with any of the other elements, hereinafter identified, which rotate together with the armature shaft 21. The spaces between the two bearing races 39 and 41 and between the two shields 42 and 43 are filled with a suitable lubricant.

Fitted over the outside surface of the housing 33 and fastened thereto is another stationary cup-like housing 44. The housing 44 which may be formed from sheet aluminum or the like extends for a substantial distance in an axial direction beyond the end of the housing 33. Within the space defined between the outer end wall of housing 33 and the interior end wall of the housing 44 there is located a first stage centrifugal impeller 45 and a first stage stationary diffuser 46.

At one end of the cup-like housing 44 there is provided an opening 47 through which airstreams A can flow into a second or final stage centrifugal impeller 48. Within the cup-like housing 44 and arranged parallel to an inside wall surface thereof there is a centrally apertured oircular disc 49. Between the housing 44 and the disc 49 there is situated a plurality of spaced-part spiral-like vanes 50. The vanes 50 are radially arranged in the space between a wall of housing 44 and the disc 49. Each vane 50 has projecting ears such as the ear 51. These ears 51 extend through accommodating holes in the housing 44 and in the disc 49 and are bent over onto the outside surfaces of the housing and the disc. To ensure a positive connection to the housing 44 and to the disc 49 the bent over ears 51 of the vanes 50 may be spot welded thereto. As may be seen in FIG. 1 the central aperture in the disc 49. has a diameter large enough to allow the armature shaft 21 and the other elements coupled therewith to rotate freely without interfering with the disc 49. Thus, the first stage difiuser 46 is comprised of the stationary end wall of housing 44, the disc 49 and the vanes 50 situated therebetween.

T-he first stage centrifugal impeller 45 is located between the wall member 33 and the stationary difi'user 46, as shown in FIG. 1. The impeller 45 is comprised of two spaced-apart circular discs 52 and 53 and spiral-like radially arranged vanes 54 connected therebetween. Each vane 54 includes a plurality of ears,-such as the ear 55, which protrude through accommodating holes in the discs 52 and 53. These ears 55 are bent over and may be spot welded to the outside surfaces of the discs. As shown, the disc 52 has a large diameter central aperture 56 which admits airstreams A into the impeller 45.

The second or last stage impeller 48 is comprised of two spaced-apart circular discs 57 and 58 and radially arranged spiral-like vanes 59 connected therebetween. These vanes 59 are regularly spaced-apart between the discs '57 and 58 and each vane includes a plurality of ears 60 which protrude through accommodating holes in the discs 57. and 58 and are bent over and may be spot welded to the outside surfaces of these discs. As shown the disc 57 has a large diameter central aperture 61 to admit airstreams A into the final stage impeller 48.

The armature shaft 21 has an enlarged section 62 having a diameter greater than the remainder of the shaft 21. At the juncture of the enlarged section 62 and the smaller diameter portion of the armature shaft there'is defined an annular shoulder 63 against which one end of the inner bearing race 39 is in contact and situated next to the opposite end of the bearing race 39 is a flanged cylindrical body 64. One end of this body 64 is in contact with the, end of the bearing 39 and the flanged portion therewith is a centrally apertured cylindrical. body 66 which also encompasses the armature shaft 21. Situated between the opposite end of the cylindrical body 66 and the face of the disc 58 is another centrally apertured washer 67 which also encompasses the shaft 21. In contact with the opposite face of disc 58 is another centrally apertured Washer 68 which also encompasses the armature shaft 21. The end of the armature shaft 21 is externally threaded and it receives an internally threaded nut '69 which is tightened so as to bear with considerable force against the face of the washer 68. The force exerted by nut 69 is transmitted to the annular shoulder 63 through the washer 68, disc 58, washer 67, cylindrical body 66, washer 65, disc 53, flanged body 64 and the inner bearing race 39. Thus, all of the aforementioned part-s between the shoulder 63 and the nut 69 and including the nut 69 rotate together with the armature shaft 21 due to the high pressure contact therebetween. Also since the discs 52 and 57 are rigidly secured to the discs 53 and 58 through the

vanes

54 and 59 respectively in the manner hereinbefore set forth, the first and

second stage impellers

45 and 48 defined by these vanes and discs rotate together with the armature shaft 21.

A dish-like wall or cup member 70 formed in a somewhat frusto-conical shape from suitable sheet metal, such as aluminum, is secured to the outside of the housing 44 by means of the evenly spaced brackets 71 and the sheet metal screws 72. The mounting brackets 71 are spot welded to the inside surface of the wall member 70 and the sheet metal screws 72 are threaded through the brackets 71 and the walls of the

housings

33 and 44, as indicated at FIG. 1, so that the wall member 70 is maintained in a spaced relationship relative to the housing 44.

As shown in FIGS. 2 and 3 the volumetric space between the tip of the final stage impeller wheel 48 and the inside surface of the wall member 70 which is above the tip of the wheel 48 is somewhat annular. This space wouldv be perfectly annular except for the curvature of that portion of the wall member 7 0 which is above the tip of the impeller wheel 48. Contiguous with the aforesaid annular space and extending axially therefrom is the annular frusto-conical diffuser space extends longitudinally from the line L1 to the line L2 (see FIG. 2), and is bounded by the inside surface of the wall member 70 and the outside surface of the housing 44. As shown in FIG. 2 the Wall member 70 is outwardly flared at an angle B relative to the wall surface of the housing 44.

Tests, hereinafter discussed in detail with reference to FIGS. 7 and 8, were conducted to determine relative performance of a reverse-flow motor-fan unit having, in accordance with my invention, an annular frusto-conical diffuser and a like motor-fan unit having a conventional prior art annular cylindrical difiuser. These tests showed that the motor-fan unit incorporating the aforesaid annular frusto-conical diffuser produced a higher suction or vacuum over its entire airflow range than the comparable motor-fan unit employing the conventional prior art diffuser.

While it is not fully understood why the motor-fan unit employing my annular frusto-conical diffuser performs better than the prior art motor-fan units the following explanation, based on FIGS. 3 and 4, seems to account for the improved performance. However, I do not wish to be bound by such explanation.

In FIGS. 3 and 4 there exists the following relationship between the angles B, C and D.

tan DSin C-tan B In the above equation B is the angle at which the wall member 70 is disposed relative to the housing 44 (see FIG. 2). C is'the angle at which the airstreams A exit into the diifuser space which is defined between the wall member 70 and the housing 44. The angle C was measured by observing the position which a thread assumed when it was inserted into the annular space above the tip of the final stage impeller wheel 48. The'angle D, which is calculated from the above equation, is the diverging angle at which it is believed the airstreams A difiuse into the annular frusto-conical diffuser space.

In one illustrative embodiment of my invention the ang e B was set at 17 and the angle C was measured with the aid of a thread to be 20. The angle D was calculated to be 6. For air a diffusion angle of between 6 and 8 is considered to be the range which permits the air to diffuse with the least loss of energy. Thus it seems plausible that the reason for the improved performance of a fan unit embodying my annular frusto-conical diffuser is that airstreams can seek an effective diffusion angle of between 6 and 8 which diffusion angle permits the air to convert its velocity energy into pressure energy with the least energy loss.

Another embodiment of my invention is shown in FIGS. 5 and 6. The motor-fan unit shown in these figures is similar to the motor-fan unit shown at FIGS. 1 and 2 so that no further description is necessary, but in FIGS. 5 and 6 a separate airflow is provided for cooling the motor 16 by virute of a bladed fan 110 fixed on the motor shaft at the end remote from the centrifugal fan 18. The motor 16 is enclosed within a separate compartment 111 defined by a cylindrical wall 106 and the impervious or continuous base portion 109 of the motor frame. The cylindrical wall member 106 is snugly fitted onto the frame 108 and terminates short of the series of opening 104 between the frame portions 108 and 109. Cooling air for the motor is drawn into the compartment 111 by the fan 110 through a plurality of openings 102 communicating with the shroud 103 concentrically surrounding the fan 110. This air passes through the open portion of the motor frame, over the motor and exits from compartment 111 through the openings 104 which communicate with channel 105 defined by wall 107. Air recirculation between channel 105 and the shroud 103 is prevented by an O-ring 112 as shown in FIG. 5. The cooling air is discharged to atmosphere through suitable openings 113 in the housing 101. Of course the channel 105 may extend radially so that air is discharged from the compartment 111 radially rather than axially as shown.

In the embodiment according to FIG. 5 airflow through the fan 18 passes into the diffuser 170 formed integral with the motor frame. The diffuser 170 is identical with the diffuser 70 of FIG. 1 except that air passes through the diffuser in the same axial direction as the airflow through the fan 18. Air discharged from the diffuser 170 enters the relatively large space 120 within the dome 101 and passes to atmosphere through a baffied aperture 121. Radially extending air guide vane 173 may be connected with the wall 106 in any suitable manner such as by welding. The vanes 173 extend into the space 120 and are evenly spaced from one another and may extend across the space 120 up to the wall 101.

Three reverse flow motor-fan units were tested and the tests appear in graphic form in FIGS. 7 and 8. Motorfan unit I was provided with a conventional vaneless annular cylindrical diffuser wherein the wall member 70 was maintained parallel to the housing 44 rather than disposed at the angle B as shown in FIG. 2. Motor-fan unit II was provided with an annular frusto-conical difi'user of the kind shown in FIGS. 1 and 2. Motor-fan unit 111 was provided with the annular frusto-conical diffuser and the vanes 73 as shown in FIGS. 5 and 6. In each of the three motor-fan units the diameter of the fan housing 44 was approximately 5.3 inches. The diameter of the impeller wheels are approximately 4.9 inches and each impeller wheel had an axial length of about 0.3 inch. In motor-fan unit I a constant distance of approximately 0.120 inch was maintained between the wall member 70 and the housing 44. In motor-fan units 11 and III the throat dimension T indicated in FIG. 2 was maintained at 0.120

6 inch. In motor-fan units II and III the angle B of the wall member 70 relative to the housing 44 was maintained at 17.

A comparison of the motor-fan units II and III with the motor-fan unit I in FIG. 7 shows that the motor-fan units II and III provided a higher suction over the entire airflow range as compared with the suction produced by motor-fan unit 1, Further, motor-fan unit 111 produced an even higher suction over its entire airflow range than motor-fan unit II. Moreover, as appears in FIG. 8 the higher suction produced by motor-fan units II and III was achieved at but a relatively insignificant increase in input power.

While I have disclosed two more or less specific embodiments of my invention it is to be understood that this has been done for purposes of illustration only. Also, although I have shown my invention in connection with reverse-flow motor blower units, it is equally applicable to direct-flow blowers and to blowers having separate cooling of the motor, and the scope of my invention is to be limited only by the appended claims.

What is claimed is:

1. A vacuum cleaner comprising a tank member having openings at each end, dust collecting means communicating with one of said openings for separating entrained solids, a motor-fan unit within said tank for drawing air into said One opening and discharging this air from the other of said openings, said motor-fan unit including a multi-stage centrifugal impeller means including at least one impeller discharging air at its periphery, means defining a diverging diffuser space in communication with said one impeller for receiving the discharging air therefrom at the smaller area of said diverging diffuser, a second diffuser space within said tank adjacent the other of said openings for receiving air from said diverging diffuser, means defining a discrete compartment enclosing the motor of said motor-fan unit, separate means for communicating said compartment with ambient atmosphere, and separate fan means within said compartment for circulating cooling air over said motor; said means defining a discrete compartment enclosing said motor comprises a generally cup-shaped shroud connected to the motor frame, wall means forming a channel in said shroud, said channel being open at each longitudinal end, an aperture in said motor frame communicating with one end of said channel and the other end of said channel opening to atmosphere at the end of said tank having said other opening.

2. A vacuum cleaner according to claim 1 with the addition of air guide means in at least one of said diffuser spaces.

3. A vacuum cleaner according to claim 1 wherein the angle of said diverging diffuser space is substantially 17 degrees.

4. A vacuum cleaner according to claim 1 wherein said means for communicating said compartment with ambient atmosphere includes means defining a channel connected with said compartment remote from said separate fan means,

References Cited UNITED STATES PATENTS 2,021,298 11/1935 Forsberg 230--117 2,534,808 12/1950 Bevington et al 230117 2,898,031 8/ 1959 Voigt 230-127 2,336,716 12/ 1943 Clements 2301 17 FOREIGN PATENTS 266,219 2/ 1927 Great Britain.

282,797 10/ 1928 Great Britain.

611,870 10/ 1960 Italy.

HENRY F. RADUAZO, Primary Examiner.