U.S. patent number 3,733,150 [Application Number 05/124,026] was granted by the patent office on 1973-05-15 for motor-fan unit for moving wet working air.
This patent grant is currently assigned to Ametek, Inc.. Invention is credited to John H. Porter, Robert O. Swift.
United States Patent |
3,733,150 |
Porter , et al. |
May 15, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
MOTOR-FAN UNIT FOR MOVING WET WORKING AIR
Abstract
In an electric motor fan unit for environments such as washing
machines, vacuum cleaners, air samplers, a motor section frame
enclosing an internal motor cooling air path includes an end
bracket with an enlarged rim for mounting fan shell and interior
partition structures defining a fan section housing for a smaller
motor ventilating impeller and a larger working air centrifugal
impeller commonly mounted on the motor shaft outboard of the motor
section frame and drawing respective air streams into housing axial
inlets for discharge at the housing circumference. Back-to-back and
axially spaced impeller dispositions and corresponding housing
structures and also resultant direction of ventilating air from the
motor to the air discharge region ensure both adequate motor and
adjacent bearing ventilation and bearing protection from working
air borne moisture, contaminants, and high temperature and
humidity, by simple, low cost, durable structure.
Inventors: |
Porter; John H. (Talmadge,
OH), Swift; Robert O. (Stow, OH) |
Assignee: |
Ametek, Inc. (New York,
NY)
|
Family
ID: |
22412329 |
Appl.
No.: |
05/124,026 |
Filed: |
March 15, 1971 |
Current U.S.
Class: |
417/424.1;
415/98 |
Current CPC
Class: |
F04D
25/082 (20130101) |
Current International
Class: |
F04D
25/08 (20060101); F04D 25/02 (20060101); F04b
035/04 () |
Field of
Search: |
;417/427,423R,424,368,371 ;415/98,101,102 ;310/62 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Freeh; William L.
Assistant Examiner: Winburn; John F.
Claims
We claim:
1. In an electric motor fan unit, including
an electric motor section having motor frame structure supporting
and enclosing rotor and stator structure with motor ventilating air
passages defined therethrough from a ventilating air inlet to a
motor frame portion at one end open for discharge of ventilating
air,
said frame structure at said one end including a motor end bracket
having therein a bearing for the rotor shaft extending therethrough
and having an end rim portion with ventilating air discharging open
frame areas around the locus of the bearing,
and said unit further including
a fan section having therein at least one main working air impeller
clamped outboard on the shaft portion extending through said
bearing and a fan housing structure including housing shell means
providing an end wall centrally apertured to form an axial working
air inlet to said main impeller and a further wall
circumferentially surrounding the said main impeller,
said housing shell means having therein main air outlet means and
having an open end supported on said end rim portion,
that improvement comprising:
partition means mounted to said rim portion and forming an inmost
end wall of said housing structure,
said inmost end wall centrally apertured providing around said
shaft an axial inlet to said housing for ventilating air
discharging from said motor section; and a centrifugal ventilating
air impeller secured on said shaft between said main impeller and
said inmost end wall;
said impellers being separate impeller units secured back-to-back
on the shaft in a common chamber defined between the said end walls
and with the impeller inlet openings facing the respective said
axial inlets, whereby ventilating air and working commonly
discharge through said main air outlet means.
2. An electric motor fan unit improvement as described in claim 1
with
said main air outlet means offset away from the periphery of the
main impeller toward said inmost wall, and
said ventilating air impeller having a smaller diameter than said
main impeller,
whereby ventilating air discharging from the smaller impeller
sweeps the space between said inmost wall and the working air path
of discharge to said main outlet means.
3. An electric motor fan unit improvement as described in claim 1,
with
said partition means provided by a cup-shaped member having a short
cylindrical wall portion fitted and secured on the exterior of said
rim portion and a generally radial, centrally apertured wall
portion as said inmost end wall, and
said housing shell having its open end fitted over the cylindrical
wall portion of the last said member and thereby secured to said
rim portion.
4. An electric motor fan unit improvement as described in claim 1,
with
said partition means provided by a centrally apertured disk-like
member forming said inmost end wall and secured to said end bracket
and circumferentially sealing to said rim portion, and said housing
shell means having said open end fitted on the said rim
portion.
5. An electric motor fan unit improvement as described in claim 1,
including
a spacer sleeve on said shaft, with one end abutting a part of said
bearing axially fixed on and rotating with said shaft and having on
its other end a radial flange supporting portions of said
ventilating and main impellers centrally apertured for successive
reception of the shaft, and
clamping nut means threaded onto the outboard shaft to clamp said
impellers against the said flange.
6. In an electric motor fan unit, including
an electric motor section having motor frame structure supporting
and enclosing rotor and stator structure with motor ventilating air
passages defined therethrough from a ventilating air inlet to a
motor frame portion at one end open for discharge of ventilating
air,
said frame structure at said one end including a motor end bracket
having therein a bearing for the rotor shaft extending therethrough
and having an end rim portion with ventilating air discharging open
frame areas around the locus of the bearing,
and said unit further including
a fan section having therein at least one main working air impeller
clamped outboard on the shaft portion extending through said
bearing and a fan housing structure including housing shell means
providing an end wall centrally apertured to form an axial working
air inlet to said main impeller and a further wall
circumferentially surrounding the main impeller,
said housing shell means having therein main air outlet means and
having an open end supported on said end rim portion,
that improvement comprising:
partition means mounted to said rim portion and forming an inmost
end wall of said housing structure,
said inmost end wall centrally apertured providing around said
shaft an axial inlet to said housing for ventilating air
discharging from said motor section; and a centrifugal ventilating
air impeller secured on said shaft between said main impeller and
said inmost end wall,
further separate partition means supported on said rim portion and
providing a centrally apertured intermediate wall dividing said
housing structure into an outer, main impeller chamber and an
inner, ventilating air impeller chamber,
means supporting said ventilating impeller in the respective said
chamber axially spaced outboard from said bearing, and
spacer sleeve means supporting said meain impeller spaced on said
shaft from said ventilating impeller and located in the other said
chamber, and clamping nut means threaded onto the outboard shaft
end to clamp the last said impeller.
7. An electric motor fan unit improvement as described in claim 6,
with
the said further partition means provided by a member having a
short cylindrical wall portion with an open end secured on the said
rim portion and a generally radial, centrally apertured wall
portion as said intermediate wall, and
said housing shell means having its open end secured on the
cylindrical wall portion of the last said member and thereby
supported on said rim portion.
8. An electric motor fan unit improvement as described in claim 7,
with
the first said partition means provided by a centrally apertured
disk-like member as said inmost end wall and having a
circumferential flange of narrow u-shaped cross section
press-fitted into said rim portion.
9. An electric motor fan unit improvement as described in claim 7,
wherein
the cylindrical wall of said further partition means is provided
with a plurality of equi-spaced apertures for discharge of air from
the ventilating air impeller chamber.
10. An electric motor fan unit improvement as described in claim 7,
wherein
said ventilating air impeller has a smaller diameter than the main
impeller, and
said intermediate wall is provided with a circular series of
apertures spaced outwardly of the periphery of the ventilating air
impeller as air outlets for the ventilating impeller chamber to the
main impeller chamber,
whereby ventilating air and working air streams discharge commonly
from the main impeller chamber through said main air outlet
means.
11. An electric motor fan unit improvement as described in claim
10, with
said main air outlet means comprising a circumferential series of
spaced air outlet apertures adjacent said intermediate wall in the
cylindrical wall portion of said housing shell,
said main impeller spaced axially from the intermediate wall beyond
the locus of the last said series, and
said circular series located radially between the peripheries of
said impellers,
whereby ventilating air discharging from the ventilating impeller
chamber sweeps the space between said intermediate wall and the
working air path of discharge to said main impeller outlet
means.
12. An electric motor fan unit improvement as described in claim 6,
wherein
the aperture of said intermediate wall has a close running
clearance with said spacer sleeve means extending therethrough.
13. In an electric motor fan unit, including
an electric motor section having motor frame structure supporting
and enclosing rotor and stator structure with motor ventilating air
passages defined therethrough from a ventilating air inlet to a
motor frame portion at one end open for discharge of ventilating
air,
said frame structure at said one end including a motor end bracket
having therein a bearing for the rotor shaft extending therethrough
and having an end rim portion with ventilating air discharging open
frame areas around the locus of the bearing,
and said unit further including
a fan section having therein at least one main working air impeller
clamped outboard on the shaft portion extending through said
bearing and a fan housing structure including housing shell means
providing an end wall centrally apertured to form an axial working
air inlet to said main impeller and a further wall
circumferentially surrounding the said main impeller,
said housing shell means having therein main air outlet means and
having an open end supported on said end rim portion,
that improvement comprising:
partition means mounted to said rim portion and forming an inmost
end wall of said housing structure,
said inmost end wall centrally apertured providing around said
shaft an axial inlet to said housing for ventilating air
discharging from said motor section; and a centrifugal ventilating
air impeller secured on said shaft between said main impeller and
said inmost end wall;
said housing shell means comprising a cup-shaped member integrally
providing the end wall having said axial working air inlet and a
cylindrical wall for circumferentially surrounding said main
impeller,
said cylindrical wall having therein said main air outlet means and
having its open end supported on a cylindrical formation on said
rim portion;
said partition means secured at the external circumference thereof
to said rim portion and including
a centrally apertured disk-like member as said inmost end wall and
having a circumferential flange of narrow U-shaped cross section
press fitted into said portion.
14. An electric motor fan unit improvement as described in claim
13, wherein
said partition means further includes a cup-shaped member with open
end fitted on said rim portion and providing a centrally apertured
intermediate wall dividing said housing structure into an outer,
main impeller chamber and an inner, ventilating air impeller
chamber, and
means supporting said ventilating and main impellers in the
respective said chambers axially successively spaced from said
bearing;
said housing shell having its open end fitted on the cylindrical
wall portion of the last said member and thereby supported on said
rim portion.
Description
Though discussion and description here is presented mainly in terms
of vacuum cleaner motor fan units, it is to be understood that
described inventive features may find use in other applications of
the motor fan unit.
In modern vacuum cleaners of various types, commonly the fan system
for pumping or moving the vacuum cleaning air stream, the so-called
"working air", and the electric motor therefor, generally a
commutating series universal type motor, are fabricated as a unit
to be assembled into the overall appliance, that is, as a motor fan
unit, because of various considerations relating to overall cost,
facility of production, fabrication and maintenance, and as well
because of the mechanical interrelation of the fan system and motor
system wherein dynamic balance of the rotating parts is
required.
Because of heat generated under the general and normal operating
conditions, the motor must be cooled by a ventilating air stream
positively moved, rather than relying upon convection or
radiation.
In many prior art structures, all or part of the working air has
been directed to the motor section either in reaching the air
intake of, or in discharging from, the main working fan section;
but various disadvantages attendant upon such systems have led to
use of a separate motor ventilating fan to move a cooling air
stream separate and distinct from the working air and of structures
to define a ventilating air flow path or paths through the motor
structure.
Generally speaking such separate ventilating fan has been mounted
on the motor shaft at a location axially between the bearings
within the main motor housing or frame, though at times outboard of
one or the other end bearing in enclosure means usually partially
defined by part of the motor frame structure. Prior expedients for
this purpose have generally involved structure or fabrication
operations entailing additional cost of parts, and/or inconvenience
or cost in assembly, testing and balancing.
Especially where the motor fan units may be called upon to handle
not only dry air, that is, carrying merely the water vapor of the
ambient atmosphere, but also wet working air streams, as where the
vacuum cleaner unit is operated on wet floors or shampooed
carpeting, for example, further problems arise. First, the use of
the working air as ventilating air obviously would be unsuitable
not only for the reasons which have lead to abandonment of such
system even where "dry operations" solely are contemplated, but
also because of the potential motor damage by moisture, and as well
danger of shock to a user, unless special and costly preventative
expedients are used in the motor structure.
Further even where a separate ventilating air stream is used, there
still exists a hazard especially to the motor bearing at the
fanward end of the unit, where the working air is wet, as a portion
of the contained water may find its way along the shaft and through
shaft accommodating housing openings, ultimately to the bearing and
even beyond into the motor interior, unless special structural
precautions are taken to provide effective sealing between the
shaft and surrounding housing or shell structures to prohibit
moisture or water access to the bearing. Previous solutions to
these problems generally have required structure or manufacturing
operations involving costs of additional parts, and/or
inconvenience or costs in assembly.
Moreover, the fact that the working temperature of the air often
may be rather high engenders a further problem both generally for
bearing cooling adjacent the fan section and as well through the
possibility of temperature accelerated bearing deteriorating action
of the moisture.
It is the general object of the present invention to provide a
motor fan unit of relatively low cost and of simple and rugged
structure (as compared to the prior art devices of similar
performance and life ratings), wherein the motor is ventilated or
cooled by an air stream other than the working air stream.
It is a further object of the present invention to provide a motor
fan unit wherein, by relatively simple and low cost expedients,
there is afforded to the fanward end bearing protection against
damage by moisture, detergents, or other substances brought into
the motor fan unit by the working air.
It is a still further object of the present invention to provide a
simple arrangement whereby the motor section ventilating fan and
the direction of the cooling air stream path serve not only for
motor cooling, but also for protection of the fanward end bearing
against damage by working air borne water and other materials.
Other objects and advantages will appear from the following
description and the drawing wherein:
FIG. 1 represents a motor fan unit embodying the present invention,
shown partially in elevation and partially in longitudinal
section;
FIG. 2 is a fragmentary longitudinal sectional view indicating a
variation of FIG. 1;
FIG. 3 is a fragmentary longitudinal section representing a
modification of the invention; and
FIG. 4 is a fragmentary longitudinal section indicating a variation
of FIG. 3.
In the drawings, FIG. 1 shows a motor fan unit incorporating the
invention comprising a motor section designated as a whole by the
general reference letter M, including a stator structure S, and
rotor R having a shaft 11; and a fan section designated as a whole
by the general reference character F, including a main or working
air suction fan or impeller I mounted on the rotor shaft and
enclosed in a fan shell or housing as hereinafter more fully
described.
In the motor section M, here shown as a commutating motor, the
stator structure includes a first or fanward motor and bracket
casting 12, to the left end of which a second end bracket casting
member 13 is secured by bolts 14 passed through arcuate rim slots
in 13 to provide, for the brush holder structures 15 carried on 14,
an angular adjustability relative to the field core and winding
assembly 17 secured in member 12.
The shaft 11 of the commutating armature is supported by
appropriate bearings 19 and 20 in bearing sockets of respective
integral spider portions bridging the open ends of members 13 and
12, the latter of which enlarges through radial wall 12a into an
integral cylindrical rim portion 12b supporting the fan section
housing shell and partition members 23 and 25 as hereinafter
described.
As evident in the drawing, the left end bracket member 13 provides
an open structure permitting cooling air to enter into the motor
section both around the bearing socket supporting bridge portion of
13, and around the brushes and commutator, and thence to flow
lengthwise both between the wound field structure and the rotor or
armature on the one hand and on the other externally between the
field structure and the enclosing motor frame housing formed by
members 12 and 13, as permitted by longitudinal passages formed by
clearances arising by the external shape of the field, particularly
in its core or lamination stack.
The structure thus far described in detail may be considered to be
conventional.
At the fan section, a main fan shell 23 is a drawn sheet metal
cup-shaped member having a generally flat disk-like radial end wall
23a centrally apertured to provide an axial vacuum intake air inlet
23b. Member 23 includes a generally cylindrical wall 23c with one
end rounding into 23a and the other mounted on the exteriorly
cylindrical rim portion 12b of motor end bracket 12, by being
telescoped in a press fit upon the somewhat necked-down right end
of a cylindrical wall portion 25c providing effectively a
continuation of wall 23c in a similar drawn sheet metal cup-shaped
member 25 providing a partition 25a.
The member 25, which here provides an innermost end wall of the fan
section housing, at 25c may be either merely press fitted onto 12b
up against the integral circumferential stop rib 12f or further
secured by a local staking, as at 25s, into an underlying rim
groove.
Again the flat radial wall 25a has a central opening 25b defining,
for the motor ventilating air, an outlet from the motor section and
an inlet into the fan chamber to the motor ventilating air impeller
V. The fan shell or impeller housing thus defined by members 23 and
25 is provided with discharge outlet means on its circumference,
either a semi-scroll type outlet or as here shown a circumferential
series of equi-spaced, louver-like openings 23d formed in wall 23c
for air discharge.
On the portion of shaft 11 projecting to the right through the
bearing 20 into the fan section housing, a spacer sleeve 26 bearing
endwise against the inner bearing race at 20, in turn axially
located by engagement with a shaft shoulder, through a disk-like
flange 26a supports the main body disk 28 of the ventilating fan
centrifugal impeller V and the similar body disk 29 of main fan or
working air centrifugal impeller I clamped thereagainst in
back-to-back relation by clamp washer 30 and a clamping nut 31
threaded onto the extreme shaft end.
The two impellers I and V here are, per se, of generally
conventional form and structure, as, for example, made from sheet
metal; in V comprising a second annular disk 28d with central
opening defining the impeller air intake, and a series of
appropriately shaped vanes or blades 28b with opposite end edges
secured to 28d and 28; and in the impeller I comprising series of
blades 29b and the annular disk 29d forming the intake opening to
which the working or cleaning air flows through the inlet 23b in
the housing outer wall 23a.
It will be observed that the ventilating impeller V has a diameter
markedly smaller than the main impeller I, also that the series of
air discharge apertures 23d are axially offset toward the partition
means 23, away from the discharging periphery of impeller I. This
structure with the known offset of the discharge apertures from I
by virtue of the smaller diameter of V additionally minimizes noise
effects and conduces to efficiency, while yet permitting sufficient
ventilating air flow for motor cooling and other desirable
purposes.
With this arrangement, and so also those of the other subsequently
described figures, it is apparent that, apart from the motor
ventilating fan, the essential motor components are all included as
a basic sub-assembly in the motor section, and that no particular
special structure must be included in the motor section components
for accommodation of the ventilating fan. Obviously these
arrangements may be utilized in multi-stage fan units, for example,
in a two-stage unit where aperture 23b is the second stage inlet,
with stationary vanes on the right face of wall 23a; and with
another cup-shaped member, similar to 25, pressed onto the end of
23 in the manner of 23 on 25, to enclose a first stage impeller,
like to and similarly spaced by a sleeve from I and clamped on a
longer shaft extension.
Particularly noteworthy, in the event moisture is carried by the
main working air stream entering at 23b during operation of the fan
unit, there is no opportunity for such air to bring entrained water
droplets or even warm moist air, often occurring with high humidity
and temperature, anywhere near the fanward bearing region of the
motor section, since the motor ventilating air stream discharging
through 25b into impeller V not only functions for the motor and
bearing cooling, but also in effect serves as an air curtain over
the entire region of its path, from the bearing on out through the
space between the exposed inboard side of impeller I and wall 25a,
to the discharge outlets 23d thus screening the motor end the,
bearing and partition 25a not only from entrained water but also
moist warm air.
In the variation of FIG. 1, shown by fragmentary FIG. 2, the
cylindrical wall portion 23c of fan shell 23 is press fitted
and/or, if desired, staked directly onto the motor end bracket
member rim 12b, while the inner partition, which with member 23
defines the impeller chamber, takes the form of a centrally
apertured slightly conical disk 35, having an axially inwardly
offset rim portion 35r of narrow U-shaped cross section providing a
nearly cylindrical flange 35f pressed within the rim 12b, to the
extent limited by stop lip 35p. The two impellers I and V are
clamped similarly to FIG. 1, the spacer 36 with headed or flanged
portion 36f to aid clamping, merely being shortened.
The modification of FIG. 3 is identical to the motor fan unit of
FIG. 1 in the motor section, and further, except as hereinafter
described, in the fan section in the general structure of the two
cup-shaped members 23 and 25 and in their mounting relations to
each other and to the rim structure 12b of the adjacent motor end
bracket, but differs by including a partition disk member 35, and
in the disposition of the impellers V and I, though the latter are
both outboard of the motor frame as in FIG. 1. Moreover, member 35
in its own structure and in its manner of mounting to the fan
bracket end member rim 12b is identical to the like numbered member
in FIG. 2.
In this modification, the ventilating fan impeller V is disposed
axially separately from impeller I in the distinct ventilating fan
chamber defined between members 35 and 25, impeller V being axially
located on the shaft again by the end flange 36f of a shortened
spacer 36 (similar to that in FIG. 2), and thereon clamped by a
spacer bushing 40 (in diameter substantially equal to the clamping
flange 36f) serving in turn to locate the impeller I secured as
previously by clamping washer 30 and nut 31 threaded onto the shaft
outer end.
Here the central opening in end wall 25a is reduced in diameter as
compared to that in FIG. 1 to a close running clearance with the
spacer 40; and further a circular series of equi-spaced holes 25v
provide ventilating air discharge outlets from the ventilating
impeller chamber, into the space between impeller I and wall 25a in
the main or working air impeller chamber, to flow outwardly as
previously for a common circumferential discharge through the
circumferential series of louvers 23d with the working air
peripherally discharged from impeller I. This arrangement, with the
apertures 25v for the ventilating fan chamber discharge, uses
simpler structure and parts as contrasted with the variation
indicated in FIG. 4, wherein the cylindrical wall portion 25c is
provided with a set of discharge louvers or openings 25d, such as
those at 23d in member 23.
By the modification of FIGS. 3 and 4, again the motor section
itself does not incorporate any fan or impeller structures of the
unit, which all are located rather in the fan section. Further the
working air stream is well separated and screened from the nearby
end of the motor and the corresponding bearing, while the
ventilating air path within the main fan chamber (FIG. 3) again
serves to help sweep droplets of water or other material entrained
in the working air out the principle discharge as well as screening
the partition 25 in great part from working air contact and
attendant heat transmission. The close clearance between 25 and 40
also generally minimizes the chance of water entry into the
ventilating fan chamber for approach along the shaft toward the
bearing. To the degree that water might pass wall 25a, especially
with FIG. 4, the body disk of impeller V serves as an obstruction
to moisture travel along the shaft region, slinging any liquid
outwardly for discharge with ventilating air through apertures
25d.
Though in the arrangements where the partition means includes, in
addition to the innermost housing end wall, an intermediate wall
defining inner and outer chambers respectively for the ventilating
fan and working air discharging impeller, usually it is preferred
to have the described close-running clearance between the
intermediate wall aperture and the shaft structure (that is, the
spacer sleeve in these embodiments of FIGS. 3-4), yet for some
applications the intermediate wall aperture may be notably larger,
for example, approaching the diameter of the ventilating impeller,
because of the effective bearing screening provided by the rest of
the structure and the air streams or paths resulting.
Also it is to be understood that though sheet metal constructions
are shown and described for the impellers, main fan housing shell,
and the further elements providing the named partition means
supported by the end bracket rim, one or more of these may be
molded of plastic as suitable for particular applications. For
example, in FIG. 3, the cylindrical wall portions 25c and 23c and
the intermediate wall 25a may obviously be molded as one piece,
bolted or bonded to the rim 12b, with a separate plastic or formed
sheet metal disk then applied to the outer end of the molded piece
to provide the end wall 23a.
* * * * *