Note: Descriptions are shown in the official language in which they were submitted.
Thi.s lnvention c;enerally relates -to powered implements,
and more speci:Eically concerns an improved impeller for a snow
thrower and an improved snow -thrower incorporating the impeller
for use in removal of snow from sidewalks, driveways and other
areas in which snow clearance during the winter season is
necessary.
Snow removal by means other than a simple manually powered
snow shovel has been a problem which has been addressed for
many years. Si.nce snow removal is normally carried out at
freezing or sub freezing temperatures, and in conditions in
which the user of snow removal equipment must deal wi.th
slipperiness of ground surface, and varying snow densities,
the production of a simple, lightweight, and effective snow
thrower which will operate under these conditions and make the
task of snow removal more manageable is a difficult one.
Practically speaking, since the slipperiness of the ground
surface and difficulty of moving the snow thrower into the snow
tend to make a snow thrower unwieldy and difficult to handle,
there is considerable emphasls on and demand for a unit which
is highly efficient in its use of power. This follows from
the fact that the weight of the unit i~s directly related to
the size of the power plant necessary to power it. This need
is particularly strong in the smallest snow throwing units
which are typically designed for metropolitan residential use,
since the user desires a compact, lightweight implement which
may be used in a way similar to the conventional manually
operated snow shovel, but without the back-wrenching effort of
continually lifting the snow from the surface to be cleared and
propelling it to an adjoining area.
The present invention is an improvement in snow thrower
impellers and an improved snow thrower incorporating the newly
developed impeller which appears to be more efficient, to
operate more effectively in gust wind conditions, to require
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I.ess power ancl, primarily because o~ these characteristics, to
allow the constr-lction o~ ligh-te:r weight and more maneuverable
snow throwers, and ~lso improving the performance of exis-ting snow
throwers in-to which the newly developed impeller is incorporated.
In accordance with the invention, a lightweiyht snow
thrower capable of use similar to thal: of a manually powered snow
shovel comprises i.n cornbination:
(a) a snow directing housing, including a rear wall
having a first portion whose cross-section is substantially arcuate
and a second discharge portion extending generally tangentially of
said first portion, which second portion, in normal use of the snow
thrower, extends obliquely upward and forward in the direction of
snow to be cleared at approximately ~5 relative to a horizontal
line through said second portion to maximize the distance of throw
for snow thrown along said second portion;
(b) an impeller mounted in said housing with a portion
of the periphery thereof closely adjacent to said first portion,
said impeller including a plurality of blades mounted at the
periphery thereof and including an open volume to the interior
: 20 of said impeller to permit air to pass through said impeller,
each of said blades mounted to have a working surface which is
angled inward with respect to the periphery of said impeller, and
wherein said inward angle on said blades is between 5 and 25
with respect to a radial line from an axis of rotation of the
: impeller to the outermost edge of said blades;
(c) drive means cooperating with saia impeller to provide
rotary drive of said impeller in a direction to move snow along
said rear wall from said first portion to said second portion; and
Id) handle means fastened to the rear wall to enable an
operator to manuever the snow thrower, wherein the combined weight
of said housing, impeller, drive means and handle means is suffi-
ciently small so as to allow an operator to pick up the snow thrower
and use the snow thrower by holding the snow thrower adjacent to
the ground and by pushing the snow thrower in the manner of a
~mahually powered snow shovel.
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It has been four~d th(lt arl extremely cohesive discharge
of snow Erom the snow thrower is produced. I'his discharge, by
virtue of its coh~siveness, is less suscepkible to wind gusts
than the discharge of many snow throwers. In addition, it has
been found that less power is required utilizing a snow thrower
of the present invention, which permits use of a less powerful
power source, and decreases the weight of the snow thrower
constructed according to the present invention.
Other objects and advantages of the invention will become
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apparellt upon a reading of the ~ollowing detai:led description
and upon reference to the drawings showing specific embodiments
of the invention. Referring particularly to the drawings,
wherein -the use of llke reference numerals throughout the
several views denotes like elements:
Figure 1 is a perspective view of a small electrically
powered snow thrower or power snow shovel constructed in
accordance with the pre.sent inven-tion, havlng a deflector
structure to accomplish a sideward. deflection of discharged
snow;
Figure 2 is a perspective view of a single stage snow throw-
er constructed in accordance with the present invention;
Figure 3 is a side elevational view of a portion of the
structure of the small snow thrower of Figure 1, the handle
portion thereof being partially cut away, and other portions
being partially cut away to show the internal workings of the
.~ snow thrower;
Figure 4 is a rear elevational view of a porti.on of the
snow thrower of Figure 1, the view being taken generally along
the line 4-4 of Figure 3;
Figure 5 is a diagramatic representation in side elevation
of portions of an impeller and rear wall of an impeller housing
showing important parameters of preferred embodiments of the
present invention;
Figure 6 is a sectional view vertically through the housing
of the thrower of Figure 1 at a point approximately midway across
the extent of the impeller;
; Figure 7 is a sectional view taken along the line 7-7 of
Figure 6; and
Figure 8 is a perspective view of a power shovel constructed
according to the present invention, the power shovel being
electrically powered.
While the invention will now be described in connection with
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specific embodiments, it should be clear that -the invention is
not limited in scope to -those embodiments. On the contrary,
all alternatives, modifications and e~uivalents included within
the spirit and scope of the invention as defined by -the appended
claims are covered.
The invention consists in an impeller an impeller ~or a snow
thrower, comprising:
a) a plurality of impeller blades of predetermined width;
b) impeller frame means adapted to carry and support the
blade strips along their length to maintain substan-
tial rigidity thereof during operation;
c) impeller shaft means to which said frame means are
mounted, said shaft means defining an axis of rotation
for said impeller; and
d) blade mounting means for mounting said blades in a
forward facing orientation in said frame means; said
frame means spacing said blades a substantlal distance
from one another and from said shaft means and
establishing an open volume therebetween.
In Figure 1, a lightweight single stage snow thrower
generally designated 10 is shown in perspective. A portion of
the electrical cord for that snow thrower is shown cut away
since the cord connection is not essential to the invention, and
the cord may be of extended length. Snow thrower 10 has an
impeller 12 which is housed within an impeller housing 14.
At one end of impeller housing 14 is an impeller drive linkage
and housing 16, which transfers power from an electric motor
18 to impeller 12. Power for electric motor 18 may be trans-
mitted from a cord 20 through handle 22 to electric motor 18
to promote drive of impeller 12. Handle 22 has, at one end, a
grip portion 24 which may contain a control switch controlling
power to motor 18. Handle 22 may also be provided with an
intermediate hand grip 26 fastened to handle 22 and adjustable
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alony tile length thereof to aid in operator control of the unit.
In ~he particular embodiment shown in Figure l, the impeller
housiny is provi~ed with a plurality of deflector vanes in a
deflector vane assembly 28. These deflector vanes are for the
purpose of guiding discharged snow to the riyht or left as it
is forwardly discharged from the impeller housing. Details of
the chain drive, the impeller and the vane deflector construction
are shown in successive figures.
Figure 2 shows a snow thrower generally designated 30 which
is a larger capacity snow thrower than that shown in Figure 1.
The effective width of operation of the snow thrower shown in
Figure 2 might be 20 inches, as an example, in comparison to a
probable width of 12 or 14 inches for the unit as shown in
Figure 1. In addition, the unit of Figure 2 is shown operated
by a gas powered engine. The unit of Figure 2 has an impeller
housing 32 in which an impeller 34 is housed for rotation about
a substantially horizontal axis. The unit also includes
shrouding 36 which covers a gas powered engine used to drive
the unit, a pair of handles 38, 40 for operator control of
the unit, a deflector vane arrangement 42 for deflecting snow
right or left of the unit during operation, and a deflector
control mechanism terminating in a control handle 44 which
controls the orientation of the deflector vanes. As appears
clearly in Figure 2, since it is desired to have the impeller
blades substantially rigid during operation of the unit, the
unit shown in Figure 2 has more impeller blade mounting or
support means 46, which in the embodiment shown take the form of
substantially circular plates to which the impeller blades 48
are fastened by means of right angle tabs 50. The right angle
tabs 50 are one means of making this reinforcing connection, but
a large number of other alternatives for connection might as well
be used. In one embodiment, the right angle tabs were fastened
to both the impeller blades and the blade support means utilizing
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a riveted construc-tion. As i8 illustrated ~y the embodimen-t of
Figure 2, the present invention, although it has specific
advantages in relatively small snow throwing implements, is
not limited to application -to such implements, but might very
well be incorporated in laryer scale snow throwers.
Figures 3, 4, 6 and 7 illustrate details of the embodiment
of Figure 1 and of specific parameters which are pre~erred in an
impeller constructed according to the present invention. Figure
3 shows a portion o~ the cover of the drive train 16 cut away to
reveal internal construction. In the embodiment shown in E'igure
3 drive occurs by means of a chain drive made up of a chain 52,
a small drive sprocket 54 and a driven sprocket 56. Drive
sprocket 54 is solidly affixed to the shaft of motor 18 to
transmit driving motion from motor 18 to the chain drive system.
As shown particularly in Figure 3, impeller housing 14 is
provided with motor mounting projections 58 on which motor 18
may be mounted by means of bolts 60. Ease of adjustment to main-
tain appropriate tension of the chain drive system is accomplish-
ed by means of bolts 60 in combination with a plurality of
elongated slots which permit shifting of the position of drive
sprocket 54 with respect to the impeller sprocket 56 to tighten
or loosen the chain tension.
Driven sprocket 56 may have a hub 62 for mounting to a
shaft 64 of impeller 12. In the particular embodiment shown in
Figure 3, hub 62 is adapted to receive a set screw which bears
on a flat on shaft 64 so that the driven sprocket may transmit
power through the chain drive system to impeller 12.
Figure 4 is a rear view of the structure of Figure 3 ta~en
generally along the line 4-4 thereof. It illustrates the working
of the deflector vane assembly 28. Deflector vane assembly 28
includes a plurallty of flexible vanes 66, six of which are
shown in the unit being described. Figure 4 shows these vanes
in two positions to illustrate the operation of the deflector
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Val1~ ass~mhLy~qlh~ ~r~ken lin~ position i~ a position which would
~stablish a de~L~ction to the left side of the snow thrower as
viewed from the rear by ~n op~rator. Each of the deflector
vanes 66 is fastened at a lower end ~o the housing by means of a
tab 68 which extends through the rear wall of the housing. This
is best seen in Figure 6. Tabs 68 extend through slots in that
rear wall and are secured by transversely extending projections
70 which may be inserted after the tabs 68 are placed through the
slots, may be spring biased elements affixed to the slots, or
any other suitab]e means of holdlng the lower edge of the vanes
secure in the rear wall. The upper end of each of vanes 66 is
attached by conventional means to a deflector plate 74 in a
conventional manner. The deflector 74 is laterally movable with
respect to the rear wall by means of a linkage generally
designated 76. The linkage designated 76 is shown in two
positions. The linkage pivots about a point 78 and establishes
a left deflection, right deflection, and center position for the
vanes to permit a forward and sideward deflection to be
accomplished during snow throwing. This is particularly de-
-20 sirable when cleaning of the edge of a sidewalk abutting a lawn
or other area not to be cleared is being accomplished.
Figures 5, 6 and 7 particularly illustrate the structure of
the impeller housing and the impeller built according to the
present invention. Figure 5 shows a circle 80 which represents
the periphery of the rotating impeller blades. The impeller
blades in an impeller built according to the present invention
are preferably forward facing. As used in this specification
and in the claims, "forward facing" means that their working
surfaces, defined with respect to the direction of rotation,
face inward with respect to a radial line from the center of
the impeller. Stated another way, the leading edge of the
impeller blade surface is at the periphery, and its trailing
edge is swept back with respect to a radial line from the
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outermost polnt of the b:Lacle to the center Oe the impe].ler. The
amount which th~ hlade is forward faciny ma~ be defined wi-th
respect -to the angle which the working surface of the impeller
blade makes with a radial line to its leading ed~e. This is
shown as angle A in Figure 5. The preferred angle range has
been found -to be approximatel~ 10 to 20. ~bove 25, the power
required to drive the impeller effectively increases substantially
in relation to any increases in capacity of the machine. ~lthough
the impeller may still be operable at angles below 5, it is
subject to the disadvantage of increased dribbling and scattering
of snow, and a less cohesive throw pattern results. The angle B
shown in Figure 5 refers to the portion of the rear wall of the
impeller housing which generally follows the periphery of the
impeller. This is defined by the front edge of a scraper blade
82 shown particularly in Figure 6, which may be riveted to the
bottom of the impeller housing. It is preferable ~o have the
angle B greater than 90 to allow a substantial interaction
between the snow and the impeller blades prior to release of
the snow from the impeller area of the housing. The angle C
shown in Figure 5 may be referred to as the take-off angle of
the housing. It has been found that an angle of 45 between
the point at which the housing rear wall is substantially tangent
to the impeller periphery and the edge of the rear wall is
preferred to effect substantial guiding of the snow. While a
rear wall guide portion of greater extent might be used, the 45
angle is a preferred minimum figure when take-off angle is fixed.
Figures 6 and 7 show details of the impeller construction.
In -the impeller shown, there are three blade support means or
"spiders" 84, 86, 88, to which the impeller blades are fastened.
They are fastened by means of tabs 90, which may be right angle
tabs as shown, and, in one embodiment, rivets were used to fasten
the impeller blades to the blade support means. The method of
attachment of the blades to the spider or blade support means
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s ~lot cri~ical. Ilowev~r, i~ is prefer~ble that there be
su~icient bl~de suppo~t Ineans or spiders so that -the spans of
the impeller blades are substantially rigid during operation
of the snow thrower. ~s an example, a preferred material for
the blades has been found to be Lexan ~, a plastic material of
substantial durability and rigidity. In one embodiment of
the invention in which an impeller uslng Lexan blades was
constructed, it was found preferable to have two end support
spiders and one intermediate spider across a 14 inch impeller
width.
In the impeller as shown in Figure 6 and 7, a central shaft
64 provides the basic shaft about which the impeller is con-
structed. The shaft may be journaled in bearings carried by
the side wall of the impeller housing, and the impeller blade
support means or spiders may carry hubs for fastening to the
shaft or may be welded thereto. The details of this part of
the construction will be apparent to those of ordinary skill in
the mechanical engineering arts.
Testing and experimentation with impellers of the present
invention have shown that, in a unit having a rotor with a five
inch diameter, preferred results were obtainéd utili2ing impeller
blades with a 3/4 inch to 1 1/4 inch width. Although extensive
- testing to establish a preferred proportion has not been under-
taken, it is believed that the proportion of 1 to 4 between
blade width and rotor diameter establishes an optimum value.
Also, in tests of a unit having an impeller with a five
inch diameter and fourteen inch clearing width, the optimum
range of rotor speeds has been found to be that which establishes
a tangential speed between 2,000 and 4,000 feet per minute.
Figure 8 shows an electrically powered shovel of the same
general configuration of Figure 1. The basic difference between
the unit of Figure 8 and that shown in Figure 1 is that
deflector vanes have not been incorporated in the unit of
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Figure 8. Slnce the preserlt invention allows use of a much
lighter weight powered snow moving implement, it is possible to
construct a power snow shovel which is used in a manner very
similar to a conventional manually powered shovel. With such
usage, vanes and the added weight which results from deflector
vanes will not be necessary in some embodiments. It will be
noted that in the ro-tor shown in each of the units, that is
that of Figure 1, Figure 2 and Figure 8, a three bladed
construction is used. The preferred impeller according to the
present invention has three vanes. Two and four bladed rotors
have been tried and are operative, but the preferable construction
is with three forward facing vanes 120 apart about the
periphery of the impeller.
In operation of the present invention, the impeller rotates
in the direction shown in the arrow of Figure 6 or a direction
corresponding thereto, and the forward facing blades impact the
snow to bite a portion of the snow with their leading edge and
carry it into the impeller housing. As the snow is carried
through the impeller housing it is accelerated by the blades
and given both radial and tangential components of velocity.
It is then released from the impeller, is guided by the take-off
portion and emerges from the impeller housing rear wall in a
cohesive stream which is relatively impervious to wind gusts.
secause of the improved efficiency of the unit, smaller power
plants can be used, which makes a more maneuverable and less
tiring unit available to the residential user.
From the foregoing, it will be apparent that an improved
snow thrower providing lower power consumption and better
performance has been provided. While the invention has been
described in conjunction with specific embodiments, it is
evident that a number of alternatives and modifications will
be apparent to persons skilIed in the art after reading the
foregoing description. Accordingly, it is intended to embrace
all such alternatives, modifications and variations which fall
within the ~pirit and broad scope of the appended claims.
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