U.S. patent number RE33,726 [Application Number 07/411,034] was granted by the patent office on 1991-10-29 for single stage snowthrower.
This patent grant is currently assigned to The Toro Company. Invention is credited to Richard A. Thorud, Donald M. White, III.
United States Patent |
RE33,726 |
Thorud , et al. |
October 29, 1991 |
Single stage snowthrower
Abstract
An improved single stage snowthrower (2) includes an open front
portion (14) having a rotatable impeller (30) contained therein.
Impeller (30) contains at least one outwardly extending paddle (32)
having a complex curved shape. Paddle (32) includes a central
snowthrowing section (34) which is curved forwardly from its
midpoint to each side thereof to be concave with this central
section (34) extending over at least the middle 50 percent of the
entire paddle's length. Two end sections (36) fill out the
remaining length of paddle (32) and are shaped to function as
augers for moving a relatively small volume of snow inwardly onto
the central snowthrowing section (34). Improved impeller (30) can
be used with an inverted funnel-shaped collecting chamber (22)
located in the rear wall (18) of front portion (14) of snowthrower
(2). Collecting chamber (22) is sized and shaped to approximate the
size and shape of the inwardly tapered stream which is thrown off
central section (34).
Inventors: |
Thorud; Richard A.
(Bloomington, MN), White, III; Donald M. (Chanhassen,
MN) |
Assignee: |
The Toro Company (Minneapolis,
MN)
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Family
ID: |
27021254 |
Appl.
No.: |
07/411,034 |
Filed: |
September 22, 1989 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
775288 |
Sep 12, 1985 |
04694594 |
Sep 22, 1987 |
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Current U.S.
Class: |
37/244;
37/233 |
Current CPC
Class: |
E01H
5/04 (20130101) |
Current International
Class: |
E01H
5/04 (20060101); E01H 005/09 () |
Field of
Search: |
;37/259,244,233,257,258,251,252,209-213,225,240,249,254,256,260-262,206
;198/638,640-642,657-665,669-671,676 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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627518 |
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Sep 1961 |
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CA |
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2147001 |
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Apr 1973 |
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DE |
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644096 |
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Aug 1962 |
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IT |
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197708 |
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Aug 1977 |
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SU |
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Other References
Owner's Manual for Jacobsen Sno-Blitz (May 25, 1972). .
Lawn-Boy Snow Thrower, advertisement (Aug. 1978). .
Gilson Snow-Cannon, brochure (Jun. 1978). .
Gilson--Nine Snow-Hungry Models, pp. 2-4 (Apr. 1979). .
Jacobsen, Mowers, Riders & Tractors, Brochure 80-C-1 (Jan.
80)..
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Primary Examiner: Eickholt; Eugene H.
Attorney, Agent or Firm: Miller; James W.
Claims
We claim:
1. An improved single stage snowthrower of the type having a
housing that includes a generally open front portion defined by
spaced side walls connected together by a rear wall; a rotatable
snowthrowing impeller extending between the side walls and located
in front of the rear wall; and engine means carried by the housing
for rotating the impeller: and wherein the improvement
comprises:
an impeller having at least one outwardly extending paddle for
picking up and throwing snow, wherein the paddle comprises:
(a) a central snowthrowing section which extends over at least the
middle one-half of the entire paddle's length, wherein the central
section is curved forwardly from the midpoint to each side thereof
to be generally concave such that snow is thrown in a stream that
tapers inwardly as it rises from the central section;
(b) two end sections located on each side of the central section
which fill out the remaining length of the paddle, wherein each end
section comprises a relatively small portion of one turn of a
helical auger having a relatively small pitch in relation to the
paddle's length; and
(c) wherein the central snowthrowing section faces forwardly with
respect to a radial line extending from the axis of rotation of the
central section, wherein the amount of the forward facing is from
5.degree. to 20.degree. at the midpoint of the central section and
is approximately 0.degree. at each side of the central section.
2. An improved single stage snowthrower as recited in claim 1,
wherein each end section has its axially inwardmost portion blended
into a configuration which approximates the shape of the central
section along each side thereof so that snow can move smoothly from
the end section onto the central section from which it is
thrown.
3. An improved single stage snowthrower as recited in claim 2,
wherein the end and central sections of the paddle are integrally
connected together.
4. An improved single stage snowthrower as recited in claim 3,
wherein the paddle is made from a single piece of material.
5. An improved single stage snowthrower as recited in claim 1,
wherein the paddle is made from a single piece of flexible
material, and wherein the impeller further comprises:
(a) a substantially horizontal drive shaft rotatably journalled in
the side walls of the front portion of the housing; and
(b) means for securing the paddle to the drive shaft such that the
various sections thereof are bent into and maintained in the
corresponding shapes thereof.
6. An improved single stage snowthrower as recited in claim 1,
wherein the central snowthrowing section is made from a flexible
rubber material, and wherein the rubber material has a hardness
between 55 and 65 as measured on the Shore A scale.
7. An improved single stage snowthrower as recited in claim 6,
wherein the rubber material includes at least one fabric
reinforcement layer therein.
8. An improved single stage snowthrower of the type having a
housing that includes a generally open front portion defined by
spaced side walls connected together by a rear wall; a rotatable
snowthrowing impeller extending between the side walls and located
in front of the rear wall; and engine means carried by the housing
for rotating the impeller; and wherein the improvement
comprises:
a) an impeller having at least one outwardly extending paddle for
picking up and throwing snow, wherein the paddle comprises a wide
central snowthrowing section which is curved forwardly from the
midpoint to each side thereof to be generally concave such that
snow is thrown in a stream that tapers inwardly as it rises from
the central section, wherein the central snowthrowing section
extends over at least approximately one-half of the entire
impeller's predetermined length; and
b) a funnel-shaped snow collecting chamber located on the rear wall
of the housing generally behind the impeller which chamber is
inverted to taper inwardly from side-to-side as it rises and is
wide at its lower end to receive snow from the wide central
snowthrowing section of the paddle.
9. An improved single stage snowthrower as recited in claim 8,
wherein the inward taper of the chamber is sized and shaped to
generally approximate the size and shape of the inwardly tapered
snow stream thrown from the central section of the paddle.
10. An improved single stage snowthrower as recited in claim 8,
wherein the lower end of the collecting chamber is generally
adjaent the point at which the rear wall is tangent to the paddle
with the chamber extending upwardly away therefrom.
11. An improved single stage snowthrower as recited in claim 10,
wherein the collecting chamber has an upper end formed as a ring
having upper and lower edges, wherein the upper edge of the ring is
located adjacent a snow directing chute rotatably carried on the
housing.
12. An improved single stage snowthrower as recited in claim 11,
wherein the collecting chamber is open in front up to the level of
the lower edge of the ring.
13. An improved single stage snowthrower as recited in claim 8,
wherein the paddle further includes two end sections located on
each side of the central section which fill out the remaining
length of the paddle, and wherein each end section comprises an
auger means for feeding snow inwardly onto the central section.
14. An improved single stage snowthrower as recited in claim 13,
further including downwardly directed ledges located on the rear
wall on each side of the funnel-shaped snow collecting chamber
positioned to intercept and direct downwardly any snow which is
inadvertently thrown upwardly by the end sections of the
paddle.
15. An improved single stage snowthrower as recited in claim 8,
wherein the central snowthrowing section extends over approximately
the middle seventy-five percent of the entire impeller's
predetermined length.
16. An improved single stage snowthrower of the tupe having a
housing that includes a generally open front portion defined by
spaced side walls connected together by a rear wall; a rotatable
snowthrowing impeller extending between the side walls and located
in front of the rear wall; and engine means carried by the housing
for rotating the impeller; and wherein the improvement
comprises:
an impeller including:
(a) at least one outwardly extending paddle for picking up and
throwing snow, wherein the paddle is made from flexible material
and comprises:
(i) a central snowthrowing section which extends over at least the
middle one-half of the entire paddle's length, wherein the central
section is curved forwardly from the midpoint to each side thereof
to be generally concave; and
(ii) two end sections located on each side of the central section
which fill out the remaining length of the paddle, wherein each end
section comprises a portion of a helical auger for feeding snow
inwardly onto the central section;
(b) a substantially horizontal drive shaft rotatably journalled in
the side walls of the front portion of the housing; and
(c) means for securing the paddle to the drive shaft such that the
various sections thereof are bent into and maintained in the
corresponding shapes thereof, wherein the securing means
comprises:
(i) a first means for connecting the central section to the drive
shaft such that the central section has a closed, planar face
between the drive shaft and a distal end thereof; and
(ii) a second means for connecting the end sections to the drive
shaft such that the end sections include a gap between the drive
shaft and distal ends thereof.
17. An improved single stage snowthrower as recited in claim 16,
wherein the first means includes a pair of first securing members
each having a .[.semicicrcular.]. .Iadd.semicircular .Iaddend.hub
secured to the drive shaft and further including two radially
outwardly extending flanges which are concavely curved to define
the shape of the central section, and wherein the second means
comprises a pair of second securing members each located at one end
of the drive shaft and each having a circular hub received around
the drive shaft and two radially extending ear portions which are
inclined at an oblique angle relative to the drive shaft to define
the orientation of the end sections.
18. An improved single stage snowthrower, which comprises:
(a) a housing which includes a generally open front portion defined
by spaced side walls connected together by a rear wall;
(b) a rotatable snowthrowing impeller extending between the side
walls and located in front of the rear wall and having a
predetermined length between the side walls, wherein the impeller
includes at least one outwardly extending paddle for picking up and
throwing snow, and wherein the paddle includes a snowthrowing
section which extends over at least approximately one-half of the
entire impeller's predetermined length, wherein the snowthrowing
section is curved forwardly from the midpoint to each side thereof
to be generally concave in the direction of rotation of the
impeller; and
(c) a snow collecting chamber located on the rear wall of the
housing, wherein the chamber tapers inwardly from side-to-side as
it rises, and wherein the chamber at its lower end is sufficiently
wide to span at least approximately fifty percent, but less than
one hundred percent, of the entire impeller's predetermined
length.
19. An improved single stage snowthrower as recited in claim 18,
wherein the snow collecting chamber is located on the rear wall of
the housing generally behind the snowthrowing section of the
paddle.
20. An improved single stage snowthrower, which comprises:
(a) a housing which is movable over the ground;
(b) rotatable impeller means carried on the housing for throwing
snow upwardly relative to the housing, wherein the impeller means
includes means for throwing a snow stream which tapers inwardly as
it rises away therefrom, wherein the throwing means comprises a
paddle portion which extends generally radially relative to the
impeller means and extends over at least approximately one-half of
the impeller means' total length; and
(c) means on the housing for defining a generally upwardly
extending discharge path for the snow stream which path has upper
and lower ends, wherein the lower end of the discharge path
comprises a generally open faced trough located proximate to and in
back of the snow stream as the snow stream is thrown from the
impeller, and wherein the trough is tapered inwardly from
side-to-side to conform generally in size and shape to the inwardly
tapered snow stream as it leaves the impeller means.
21. An improved single stage snowthrower as recited in claim 20,
wherein the upper end of the discharge path includes selectively
rotatable means for directing the snow stream away from the housing
in different directions.
22. An improved single stage snowthrower, which comprises:
(a) a movable housing having spaced side walls;
(b) a rotatable snowthrowing impeller carried on the housing and
having a predetermined length between the side walls, wherein the
impeller has at least one outwardly extending paddle for picking up
and throwing snow upwardly relative to the housing, wherein the
paddle has a wide snowthrowing section which extends over at least
approximately one-half of the entire impeller's predetermined
length, and wherein the snowthrowing section is curved forwardly
from the midpoint to each side thereof to be generally concave in
the direction of rotation of the impeller, whereby snow is thrown
in a stream from the snowthrowing section of the paddle; and
(c) means on the housing for defining a generally upwardly
extending discharge path for the snow stream which path has upper
and lower ends, wherein the lower end of the discharge path
comprises a trough located proximate to and in back of the snow
stream as the snow stream is thrown from the paddle, and wherein
the trough is wide at its bottom to receive snow from the wide
snowthrowing section of the paddle and is tapered inwardly from
side-to-side as it progresses from the bottom toward the top
thereof to help concentrate the width of the snow stream as the
snow stream rises from the paddle.
23. An improved single stage snowthrower as recited in claim 22,
wherein the upper end of the discharge path includes selectively
rotatable means for directing the snow stream away from the housing
in different directions.
24. An improved single stage snowthrower, which comprises:
(a) a housing having a front portion which engages the snow and
which includes a rear wall and spaced side walls, wherein the rear
wall comprises an arcuate lower portion and an upper portion that
extends upwardly relative to the lower portion;
(b) a rotatable impeller located on the housing in front of the
rear wall thereof and having a predetermined length between the
side walls wherein the rotation of the impeller describes a
cylinder that is bounded along the rear thereof by the arcuate
lower portion of the rear wall and by at least a lower section of
the upper portion of the rear wall, wherein the impeller includes
an outwardly extending paddle having a curved central snowthrowing
section for throwing upwardly away therefrom at approximately the
juncture between the lower and upper portions of the rear wall a
snow stream which has a width as it departs the snowthrowing
section of at least approximately one-half the impeller's
predetermined length and in which axially outermost portions of the
snow stream have a component of motion that is directed axially
inwardly; and
(c) upwardly extending collecting means located on at least the
lower section of the upper portion of the rear wall for receiving
the snow stream from the impeller and for conducting that snow
stream vertically upwardly, wherein the collecting means includes a
trough means which tapers inwardly from side-to-side as it rises,
and wherein the trough means at its lower end has a width which is
at least approximately one-half the impeller's predetermined
length.
25. An improved snowthrower as recited in claim 24, wherein the
trough means is generally U-shaped.
26. An improved snowthrower as recited in claim 24, wherein the
trough means is open in front along a substantial distance of the
upper portion of the rear wall to further minimize clogging.
27. An improved snowthrower as recited in claim 24, further
including an upwardly extending discharge chute operatively
associated with the trough means, wherein the chute is rotatable
relative to the housing for changing the direction of the snow
stream.
28. An improved snowthrower as recited in claim 24, wherein the
trough means includes a vertically extending rear wall bounded on
either side by triangular side walls that progressively increase in
width as the trough means rises vertically.
29. An improved snowthrower as recited in claim 28, wherein the
upper ends of the rear walls and the side walls of the trough means
are integrally blended into an upper collar that defines an upper
edge of the trough means.
30. An improved snowthrower as recited in claim 29, wherein the
upper collar is part of the housing and forms an opening which is
generally circular in shape into which said trough means
terminates.
31. An improved snowthrower as recited in claim 24, wherein the
central snowthrowing section extends over approximately the middle
seventy-five perecent of the entire impeller's predetermined
length.
32. An improved snowthrower snowthrower as recited in claim 31,
wherein the paddle further includes two end sections located on
each side of the central section which fill out the remaining
length of the paddle. and wherein each end section comprises an
auger means for feeding snow inwardly onto the central section.
33. An improved snowthrower as recited in claim 32, further
including downwardly directed ledges located on the upper portion
of the rear wall on each side of the trough means positioned to
intercept and direct downwardly any snow which is inadvertently
throw upwardly by the end sections of the paddle.
34. An improved snowthrower as recited in claim 33, wherein the
ledges are horizontally arranged and are located on the upper
portion of the rear wall beneath a top edge of the rear wall.
35. An improved snowthrower as recited in claim 34, wherein the
trough means is generally U-shaped and is open in front along a
substantial distance of the upper portion of the rear wall to
minimize clogging. .Iadd.
36. An improved single stage snowthrower, which comprises:
(a) a housing which includes a generally open front portion defined
by spaced side walls connected together by a rear wall;
(b) a rotatable snowthrowing impeller extending between the side
walls and located in front of the rear wall and having a
predetermined length between the side walls, wherein the impeller
includes means for picking up and throwing snow upwardly along the
rear wall of the housing; and
(c) a snow collecting chamber located on the rear wall of the
housing, wherein the chamber tapers inwardly from side-to-side as
it rises, and wherein the chamber at its lower end is sufficiently
wide to span at least approximately fifty percent, but less than
one hundred percent, of the impeller's predetermined length.
.Iaddend. .Iadd.37. An improved single stage snowthrower, which
comprises:
(a) a housing which includes a generally open front portion defined
by spaced side walls connected together by a rear wall, wherein the
open front portion includes an upper edge;
(b) a rotatable snowthrowing impeller extending between the side
walls and located in front of the rear wall, wherein the impeller
comprises a central snowthrowing section and two end sections
located on each side of the central section, wherein each end
section comprises auger means for feeding snow inwardly onto the
central section;
(c) an upwardly extending snow collecting chamber located on the
rear wall of the housing and having a lower end disposed beneath
the upper edge of the housing; and
(d) two downwardly facing ledges located on the rear wall of the
housing beneath the upper edge of the housing, wherein the ledges
are positioned on each side of the snow collecting chamber to lie
above the end sections of the impeller. .Iaddend. .Iadd.38. An
improved single stage snowthrower as recited in claim 37, wherein
the ledges are horizontally arranged. .Iaddend. .Iadd.39. An
improved single stage snowthrower as recited in claim 37, wherein
the ledges extend between the snow collecting chamber
and the side walls of the housing. .Iaddend. .Iadd.40. An improved
single stage snowthrower as recited in claim 39. wherein the ledges
are horizontally arranged. .Iaddend. .Iadd.41. An improved single
stage snowthrower as recited in claim 40, wherein the chamber
tapers inwardly from side-to-side as it rises. .Iaddend. .Iadd.42.
An improved single stage snowthrower as recited in claim 41,
wherein the central snowthrowing section is curved forwardly from
the midpoint to each side thereof to be generally concave in the
direction of rotation of the impeller. .Iaddend. .Iadd.43. An
improved single snowthrower of the type having a housing that
includes a generally open front portion defined by spaced side
walls connected together by a rear wall; a rotatable snowthrowing
impeller extending between the side walls and located in front of
the rear wall; and engine means carried by the housing for rotating
the impeller; and wherein the improvement comprises:
an impeller having means for forming at least one snowthrowing
paddle comprising:
(a) a central snowthrowing section and two end sections located on
each side of the central section, wherein each end section
comprises a portion of a helical auger for feeding snow inwardly
onto the central section, wherein the central and end sections are
made of a flexible material;
(b) a substantially horizontal drive shaft rotatably journalled in
the side walls of the front portion of the housing;
(c) at least one first securing member fixed to a central portion
of the drive shaft, wherein the securing member includes at least
one flange extending radially outwardly from the drive shaft to
which the central snowthrowing section is fastened, and wherein the
flange is substantially imperforate between the drive shaft and the
central snowthrowing section to define a closed face for the
central snowthrowing section of the impeller; and
(d) a pair of second securing members with one of the second
securing members received on each end of the drive shaft, wherein
each of the second securing members includes at least one ear
extending radially outwardly from the drive shaft to which one of
the end sections of the impeller is fastened, wherein the ear is
inclined at an oblique angle relative to the drive shaft to define
the helical orientation of the attached end section, and wherein
the ear is spaced from the drive shaft such that a gap is formed
between the drive shaft and each end section of the impeller.
.Iaddend. .Iadd.44. An improved single stage snowthrower as recited
in claim 43, wherein the flange of the first securing member
includes an outwardly extending ear on each side thereof located
thereon to overlap the ear on one of the second securing members,
and further including a fastener passing through the end section of
the impeller and both of the overlapped ears. .Iaddend. .Iadd.45.
An improved single stage snowthrower as recited in claim 43,
further including a pair of first securing members for fastening
the central section to the drive shaft, wherein each of the first
securing members includes a semi-circular hub with the flange
extending radially outwardly from the hub, wherein the securing
members are secured to a central portion of the drive shaft with
the hubs thereof being disposed on opposite sides of the drive
shaft and the flanges being oppositely disposed relative to one
another and spaced apart by a small gap into which the central
snowthrowing section is received. .Iaddend.
Description
Technical Field
This invention concerns a single stage snowthrower having a
rotatable paddle-type impeller for picking up and throwing snow.
More particularly, this invention relates to an improved impeller
and an improved impeller/housing combination for such a
snowthrower.
BACKGROUND OF THE INVENTION
Powered snowthrowers are well known and are generally either single
stage or two stage. A typical single stage snowthrower is
illustrated in U.S. Pat. No. 3,359,661 to Speiser. Such a
snowthrower includes a housing which is generally open in front
having spaced side walls connected by a rear wall that includes an
arcuate lower portion. A snowthrowing impeller is rotatably
journalled between the side walls to sit in front of the lower
portion of the rear wall. The impeller includes two radially
extending paddles, which are flexible for picking up and throwing
snow. The upper portion of the rear wall of the housing includes a
plurality of transversely spaced snow deflecting vanes. As the
impeller rotates, the paddles pick up snow and carry the snow
against the arcuate lower portion of the rear wall. When the
paddles diverge from the arcuate lower portion at the tangent point
where the upper portion of the rear wall begins, the forces acting
on the snow cause it to be released from the paddles and to be
thrown upwardly and outwardly generally along the upper portion of
the rear wall. Depending upon the orientation of the vanes, the
snow is thrown either forwardly or to the left or right.
The single stage snowthrower just described is so named because it
utilizes only one powered implement, namely the impeller, for both
picking up and throwing the snow outwardly away from the
snowthrower. This may be contrasted with two stage snowthrowers
which utilize two separate means for consecutively handling the
snow. In any conventional two stage, such as the 521 snowthrower
manufactured and sold by The Toro Company of Minneapolis, Minn.,
there is again a housing having an open front portion. However, a
snow gathering auger, rather than a paddle-type impeller, is
journalled in the front portion. The auger has generally opposed
left and right helical flights which gather snow and feed it
inwardly toward the center of the housing. There is an opening at
the center of the rear wall which connects the auger to a chamber
situated rearwardly thereof. This chamber includes a second powered
element, namely a high speed rotatable fan, which takes the snow
gathered by the auger and throws it vertically upwardly through a
stack. The top of the stack includes a rotatable chute that can be
rotated by a gear and handle arrangement to face toward the front
or to the left and right respectively.
Both types of snowthrowers have their own particular advantages and
disadvantages. Single stage snowthrowers are generally lighter and
less expensive than two stage snowthrowers, but they generally do
not throw snow as far or control the direction of the thrown snow
as well as do two stage snowthrowers. While two stage snowthrowers
have the ability to direct the snow to a precise location, because
of the rotatable chute on top of the stack, they lose some
efficiency because of the different directions in which the snow is
moved. The snow is first "chopped up" and moved inwardly by the
auger, then moved rearwardly into the fan chamber, then thrown
upwardly through the stack, and finally directed to the left, right
or forwardly depending upon the direction of the chute. Snow can
more easily clog in such a tortuous path. Moreover, the need for
two separate snow contacting and moving elements, namely the auger
and the fan, adds to the cost and complexity of the two stage.
There have been attempts in recent years to have what might be
called a mid-model snowthrower or a cross between a single stage
and a two stage. In such a snowthrower, as illustrated in U.S. Pat.
No. 4,322,896 to Miyazawa, only a single, rotatable impeller is
used which includes, however, opposed auger flights that feed snow
to a central section that rotates on the same shaft as the auger
flights. This central section, which is simply a flat and
relatively short paddle, takes the inwardly moving snow from the
augers and throws it up vertically through a stack and chute
arrangement somewhat similar to that found in two stages. Such a
snowthrower allegedly gives one the advantages of a two stage, more
precise directional control for example, without sacrificing the
advantages of a single stage, namely only one active snow throwing
element.
While the above noted snowthrower has attempted to successfully
combine both single stage and two stage technology, it exhibits
some disadvantages. For one thing, Applicants have discovered that
the auger sections often overfeed snow to the impeller section. In
other words, at a normal forward walking speed for the operator of
the snowthrower, the auger sections deliver snow to the impeller
section generally faster than the impeller section can remove it
from the housing by throwing it up the stack. This can contribute
to clogging of the impeller section with snow which obviously is
undesirable. Moreover, the relatively extended length of the auger
sections and the high rotational speed thereof allow such sections
to radially throw an appreciable amount of snow upwardly rather
than augering it inwardly. Accordingly, even when the impeller
section does not clog, a conconsiderable amount of snow is
recirculated instead of being clearly thrown by this snowthrower.
The physical manifestation of this is snow spit or dribbling which
extends out forwardly from the auger sections of the impeller and
which detracts from the aesthetic appearance of the snowthrower
during operation and may also lessen how fast the snowthrower can
be pushed forwardly.
SUMMARY OF THE INVENTION
The present invention provides an improved single stage snowthrower
similar to the mid-model snowthrower noted above by having only a
single rotatable snowthrowing impeller. The improvement relates to
the impeller which has at least one outwardly extending paddle for
picking up and throwing snow. The paddle includes a central
snowthrowing section which extends over at least the middle
one-half of the entire length of the paddle. The central section is
curved forwardly from the mid-point to each side thereof to be
generally concave. The paddle also includes two end sections on
each side of the central section which fill out the remaining
length of the paddle. Each end section comprises a relatively small
portion of one turn of a helical auger having a relatively small
pitch in relation to the paddle's length.
Another aspect of this invention is an impeller having a central
snowthrowing section which throws snow upwardly away from the
snowthrower housing. Two end sections are located on each side of
the central section to fill out the remaining length of the paddle.
Each end section comprises an auger means for feeding snow inwardly
onto the central section. The central and end sections are
proportioned relative to one another such that for any unit volume
of snow contacted by the snowthrower the volume of snow augered
inwardly by the end sections is less than the volume of snow thrown
upwardly by the central section, whereby overfeeding of the central
section by the end section is minimized.
Yet another aspect of this invention is an impeller having a
concave shaped central section in combination with an improved snow
collecting chamber on the housing. The rear wall of the open front
of the housing includes an inverted, funnel shaped collecting
chamber having a lower edge generally adjacent the tangent point of
the rear wall to the paddle. The inward taper of the collecting
chamber is shaped to match the inwardly tapered stream in which
snow is thrown from the curved central section of the impeller.
Finally, another important feature of this invention is to
construct an impeller of the above noted shape from a flexible
material. In such a case, the impeller will include support means
for maintaining this flexible material in the necessary curved
shape. The paddle can be made from a relatively soft rubber
material, to have better wear characteristics, and will still have
the rigidity necessary for throwing snow because of its bent
shape.
BRIEF DESCRIPTION OF THE DRAWINGS
This invention will be described in more detail hereafter, when
taken in conjunction with the following drawings, in which like
reference numerals refer to like elements throughout.
FIG. 1 is a perspective view of an improved snowthrower according
to this invention, particularly illustrating the improved impeller
having an outwardly extending paddle comprising a concave central
section surrounded by two auger shaped end sections;
FIG. 2. is a front elevational view of a portion of the snowthrower
shown in FIG. 1, particularly illustrating the improved impeller
and inverted, funnel-shaped collecting chamber on the snowthrower
housing;
FIG. 3. is a cross sectional view of the snowthrower housing taken
along lines 3-3 in FIG. 2, particularly illustrating the
funnel-shaped collecting chamber shown in FIG. 2;
FIG. 4 is a side elevational view of the snowthrower shown in FIG.
1, particularly illustrating a drive transmission for powering the
impeller;
FIG. 5 is a partially exploded perspective view of the improved
impeller of the snowthrower shown in FIG. 1, particularly
illustrating the method of construction thereof;
FIG. 6 is a cross-sectional view of the impeller shown in FIG. 5,
taken along lines 6--6 in FIG. 5, particularly illustrating one
paddle in a new condition and one paddle in a relatively worn
condition;
FIG. 7 is a top plan view of a performed paddle before it is bent
and assembled into the shape of the impeller shown in FIG. 1;
FIG. 8 is a perspective view of the impeller shown in FIG. 1,
particularly illustrating the helical shape that the augers defined
by the end sections would have taken had they been allowed to
continue around the circumference of the impeller;
FIG. 9 is a top plan view of a portion of the snowthrower shown in
FIG. 1, particularly illustrating a improved crank mechanism used
for rotating the snow directing chute around a substantially
vertical axis; and
FIG. 10 is an enlarged cross-sectional view of the gear train used
in the crank mechanism shown in FIG. 9.
DETAILED DESCRIPTION
Referring first to FIG. 1, an improved snowthrower according to
this invention is generally shown as 2. Snowthrower 2 is similar to
existing single stage snowthrowers, such as the Toro S-200 or
S-620, in that it utilizes a single powered snowthrowing impeller
30. In addition, snowthrower 2 is similar to existing two stage
snowthrowers, such as the Toro 521, in that it utilizes a rotatable
directional chute 80 for precisely controlling the direction of the
thrown snow. One major improvement in snowthrower 2 is the use of
an improved snowthrowing impeller 30 which allows a single stage
snowthrower to approximate the performance of much larger two stage
snowthrowers.
Snowthrower 2 includes a housing 4 supported for rolling along the
ground by two, spaced apart wheels 6, only one of which is shown in
FIGS. 1 and 4. A U-shaped, upwardly extending handle assembly 8 is
secured to the back of housing 4 and terminates at a height above
the ground which is convenient for being gripped by an operator.
Handle assembly 8 allows the operator to maneuver snowthrower 2 and
to push it forwardly, along with any self-propelling action
exhibited by impeller 30. An internal combustion engine 10, or any
other suitable power source, is contained inside housing 4 for
powering impeller 30. See FIG. 4 which shows engine 10 after a
removable top cover 11 that normally encloses engine 10 has been
removed for the purpose of illustration. Various rows of air vents
12 are placed into cover 11 for allowing combustion and cooling air
to reach engine 10. The precise type of engine, the manner in which
it is supported inside housing 4, and the specific components
thereof, such as the carburetor, muffler and the like, are not
important to the present invention and may be of any suitable type.
Similarly, that portion of housing 4 which encloses engine 10,
including cover 11, may be of any suitable design.
Referring now to FIGS. 1-3, housing 4 includes an open front
portion 14 in which impeller 30 is housed for contacting the snow.
Front portion 14 includes two side walls 16 and a rear wall 18.
Rear wall 18 includes a lower arcuate portion 19 which is
semi-cylindrical in shape and an upper portion 20 integrally
connected to lower portion 19. Upper portion 20 extends upwardly
and forwardly, preferably along a tangent line to the cylinder
described by rotation of impeller 30, until it terminates in an
upper edge 21 that generally defines the top of the front portion
14 of housing 4.
One important feature of front portion 14 of housing 4, especially
in combination with the improved impeller 30, is an inverted,
funnel-shaped collecting chamber 22 located at the middle of the
upper portion 20 of rear wall 18, through which the snow picked up
by impeller 30 is thrown upwardly. Collecting chamber 22 is defined
by a rear wall 23, two triangular side walls 24 that progressively
increase in width as chamber 22 rises vertically, and a generally
circular upper collar or ring 25 into which the side and rear walls
23 and 24 are connected or blended. See FIGS. 2 and 3. Collar 25
defines the upper end of collecting chamber 22 and lies within an
opening 26 in the top cover 11 of housing 4 immediately to the rear
of the upper edge 21 of front portion 14. As shown in FIG. 2,
chamber 22 is wider at the bottom than at the top to taper inwardly
as it rises. Moreover, at least over the lower portion of its
length, i.e., the portion below collar 25, chamber 22 is open in
front, not becoming enclosed until one reaches collar 25. Another
important feature of collecting chamber 22 is that its lower edge
27 lies generally adjacent the junction between the lower and upper
portions 19 and 20 of rear wall 18, i.e., at the tangent line
between rear wall 18 and impeller 30. The purpose of collecting
chamber 22 will be described in more detail hereafter.
Turning now to the construction of improved impeller 30, impeller
30 comprises a particularly effective means for gathering and
throwing snow in a single stage snowthrower 2. Impeller 30
comprises two outwardly extending paddles 32, preferably identical
in shape, which are offset 180.degree. from each other around the
circumference of impeller 30. Each paddle 32 includes a relatively
long, central snowthrowing section 34 surrounded on either side by
a relatively short, end section 36 that functions as an auger.
Central section 34 is generally concave in shape between each side
thereof, i.e., it curves forwardly in the direction of rotation of
impeller 30 from the midpoint to each side as shown in FIG. 2 by
the arrows A. Thus, as one proceeds outwardly from the midpoint to
each side of central section 34, snow will be thrown off the face
of central section 34 at gradually increasing inwardly directed
angles. This is represented by the vector arrows B in FIG. 2 which
represent the resultant force on a snow particle at that point on
the face of central section 34. The result of this configuration is
that snow during steady state operation of impeller 30 is thrown
upwardly in what appears as an inwardly tapering stream, i.e., a
stream which decreases in width as it rises upwardly.
As noted, each paddle 32 includes two end sections 36 whose primary
function is not to throw snow upwardly in the manner of central
section 34, but to take that snow which lies outwardly of central
section 34 and feed it inwardly onto central section 34. In keeping
with this, each end section 36 comprises a "dog eared" portion that
extends forwardly from each side of central section 34 and which
appears to slant slightly inwardly when viewed from direct1y above
on edge. In fact, each end section 36 comprises a relatively small
portion of one complete turn of an inwardly directed helical or
spiral auger having a relatively small pitch in relation to the
length of paddle 32. FIG. 8 is an illustration of the shape this
auger would have taken had it continued around the circumference of
impeller 30 with X referring to the auger's pitch, i.e., the
distance between adjacent flights, which as illustrated is
considerably less than the paddle's length. However, each end
section 36 does not so continue around, but is integrally joined to
the adjacent side of central section 34 so that it smoothly feeds
snow onto the central section.
While each end section 36 has been described as being relatively
distinct from central section 34, the axially inwardmost portion of
each end section 36 might be considered a transition section in
which the shape of the end section is blended to match the shape of
the central section 34 at the side thereof. However, if such a
transition section does in fact exist, it will be considered as
part of the end section for the purposes of definition herein.
One important feature of the impeller 30 is the proportioning of
the various paddle sections relative to one another. Applicants
have found that a particularly effective impeller is created when
the concave central section 34 extends over at least the middle 50%
of the impeller's total length and preferably up to the middle 75
percent or so of the impeller's length. In such a case, end
sections 36 will fill out the remaining portion of the paddle's
length on either side of central section 34. In addition, both the
central and end sections 34 and 36 are generally equal in
circumferential extent. For example, paddle 32 shown in FIG. 1,
extends over approximately 180.degree. of the circumference of
impeller 30, with central section 34 extending roughly 90.degree.,
i.e., from 0.degree. to 90.degree. of the impeller's circumference,
and end sections 36 then extending the remaining 90.degree., i.e.,
from approximately 90.degree. to 180.degree.. However, the use of
two 180.degree. extending paddles 32 as illustrated herein is not
critical to the inventon. For example, three such paddles could be
used in which each paddle would only extend over 120.degree.. In
such a case, the central and end sections 34 and 36 of paddle 32
would be downsized so that each would extend over an approximately
60.degree. circumferential extent.
Each paddle 32 is preferably made from a single piece of flexible
material, such as a fiber reinforced rubber, which may be stamped
or cut out of a large piece of stock or molded so as to be provided
in a preformed piece as illustrated in FIG. 7. Each such preformed
paddle 32 is then bent into the shape illustrated in the drawings
and described herein and maintained in that shape on a central
through shaft 38 that comprises part of impeller 30 by using two
distinct metal stampings 40 and 42. The first stamping 40 is a
generally concave stamping which helps define the generally concave
shape of central section 34 and so will be referred to herein as
the central stamping. The second stamping 42 will be referred to as
the end stamping as it likewise helps to define the auger like end
sections 36 of paddle 32.
Central stamping 40 comprises a semi-circular hub portion 44 having
two generally radially extending faces or flanges 46 on either side
thereof, flanges 46 being concavely curved to define the concave
shape of central section 34. Referring to FIGS. 2, 5 and 6, two
identical central stampings 40 are used with their hub portions 44
being mated to opposed sides of shaft 38 and secured thereto by
connecting bolts 48. Central stampings 40 will be installed so that
the flanges 46 which project to a given side of shaft 38 will have
matching concave shapes and a small gap will be provided between
the opposed flanges 46. The material which comprises paddle 32 can
then be inserted into this gap and the paddle secured thereto by
threaded fastners, such as bolts 50, which pass through aligned
openings in the flanges 46 and various holes 53 placed in the
preformed rubber paddle 32. When paddle 32 is restrained in this
fashion, the flexible material of which it is made will naturally
be bent into the concave shape required. Referring to FIG. 2, and
with respect to the length of central section 34 as defined by
central stampings 40, Applicants have discovered that a paddle
yielding acceptable results will be achieved when the length of the
hub portions 44 of stampings 40 is approximately 14 inches for a
paddle 32 having an approximately 18 inch overall length. In this
particular case, central section 34 as thus defined extends over
approximately the middle 75 percent of the length of paddle 32.
Despite the use of central stampings 40, end sections 36 of paddle
32 would otherwise be free to move, thus requiring the use of end
stampings 42 for securing them. As shown particularly in FIG. 5,
each end stamping includes a circular hub 54 having two generally
radially extending ears 56 and 58. Each of the ears is slanted at
an oblique angle relative to the axis of hub 54 to define the
inwardly slanted orientation of end section 36 as it functions as
an auger. Each end section 36 is secured with threaded fasteners 60
to the adjacent ear 56 or 58 on the end stampings 42. The use of
metal stampings 40 and 42 for securing the flexible rubber material
of paddle 32 into its necessary shape is both an economical way of
manufacturing impeller 30 and also allows the paddles to be easily
replaced if need be.
Preferably, each paddle 32 is provided in a particular preformed
shape so that central section 34 will have a slightly forward
facing angle when it is assembled between stampings 40, i.e.,
central section 34 is tilted forwardly in the direction of rotation
of impeller 30 with respect to a radial line extending out from the
axis of rotation. See the illustration of .alpha. in FIG. 6 which
designates the forward facing angle. The amount of forward facing
at the midpoint of central section 34 is preferably from 5.degree.
to 20.degree. and then gradually decreases as one moves from the
midpoint around to each side of central section 34 where the
forward facing has been decreased to approximately 0.degree.. This
helps blend central section 34 into end section 36 which preferably
lie along a radial line. While a slight forward facing on central
section 34 has been described herein, it may be dispensed with
completely with central section 34 lying merely along a straight
radial line. This can be done simply by slightly adjusting the
shape of the preformed rubber paddle before it is assembled into
stampings 40 so that it will not be deformed out of a purely radial
line as it is bent into its concave shape. If the forward facing on
central section 34 is dispensed with, impeller 30 still exhibits a
better performance than prior art impellers, through its
performance does not appear to be quite as good as an impeller 30
will the small amount of forward facing noted above.
Finally, Applicants have discovered that the choice of materials
for paddle 32 is important and when made properly yields a paddle
having much better wear characteristics. Because paddle 32 has a
concave shape over the central snowthrowing section 34, a much
softer rubber material can be used in paddle 32 which will,
however, become stiff enough to not bend backwardly while throwing
snow because of the rigidity imparted to it by the very act of
bending it into the concave shape. Rubber material for some prior
art snowthrower paddles, such as those used in the Toro S-620, will
generally be harder to resist bending under the snow load and have
a hardness measured by a durometer rating of 75 to 85 on the Shore
A scale. Applicants have discovered that a rubber material in the
range of 55 to 65 on the Shore A scale yields a satisfactory paddle
32 according to this invention because of the extra rigidity
imparted to it by its curved shape. Moreover, Applicants have
discovered that it is also preferred to use one or more layers 59
of a fabric reinforcing material inside the rubber material with
the fabric having a tensile strength sufficiently great to prevent
the rubber material from stretching. One acceptable material for
paddle 32 is a piece of rubber conveyor being manufactured by
Uniroyal and known as Uniroyal U.S. Flex C 175 which includes one
centered polyester fabric layer covered by two equal thickness
layers of SBR rubber.
Referring now to FIGS. 1 and 2, impeller 30 is horizontally
situated within the front portion 14 of housing 4 in front of rear
wall 18 and has its through shaft 38 rotatably journalled in side
walls 16 thereof using any suitable bearings or bushings 60. One
end of shaft 38 extends through one of the side walls 16 and into a
drive transmission chamber 64 located immediately outside that side
wall or formed as part of the side wall. Chamber 64 is normally
enclosed by a removable side cover 66 to prevent snow and other
debris from fouling a drive transmission 68 contained within
chamber 64. Transmission 68 selectively couples impeller 30 to
drive shaft 9 of engine 10.
Referring to FIG. 4 which illustrates chamber 64 with side cover 66
removed, transmission 68 comprises a driven pulley 70 mounted on
the end of through shaft 38 and a drive belt 71, preferably a poly
V belt, journalled around driven pulley 70. Drive belt 71 also
extends around a drive pulley 72 located on drive shaft 9 of engine
10. An idler pulley 73 is used to selectively tension drive belt 71
to transfer driving power from engine 10 to impeller 30. Idler
pulley 73 is mounted at the middle of one of the arms of a
bellcrank lever 74 with a brake roller 75 being mounted at the end
of the same arm. Brake roller 75 cooperates with a fixed brake pad
76 to quickly stop the rotation of impeller 30 when transmission 68
is disengaged. The other arm of the bellcrank lever 74 is connected
by a suitable linkage 77 to a control handle or bail 78 located at
the top of handle assembly 8. Spring tensioning forms a part of
linkage 77 so that the control bail 78 normally assumes the
position shown in FIG. 4. In this position, bellcrank lever 74 has
been rotated until brake roller 75 engages brake pad 76 and idler
pulley 73 is positioned so that there is slack in drive belt
71.
When it is desired to begin operation of impeller 30, the operator
need only place his hands on control bail 78 and squeeze it shut
against the upper end of handle assembly 8. This action will be
transmitted through linkage 77 and will rotate bellcrank lever 74
in such a direction that brake roller 75 disengages brake pad 76
and idler pulley 73 is moved downwardly in a direction which
tensions drive belt 71. This transmits power from engine 10 to
impeller 30 and the impeller will begin rotation. When bail 78 is
released, the spring tensioning will reset the elements to the
positions shown in FIG. 4 with brake roller and brake pad
engagement causing a rapid stopping of impeller 30.
While one particular type of transmission 68 has been shown herein,
any other suitable type of transmission for selectively
transmitting power from engine 10 to impeller 30 could be used. For
example, instead of the fixed brake pad 76 cooperating with brake
roller 75, a pivotal brake arm (not shown) could be used in
approximately the same position. When bellcrank lever 74 is pivoted
into its drive disengaged position such that brake roller 75 has
been pushed up against the underside of drive belt 71, the brake
arm would also be pivoted to bring a small brake pad down into
engagement with drive belt 71 on top of driven pulley 70. This
would provide an even more efficient braking mechanism than that
specifically illustrated herein if such a mechanism were
desired.
Referring now to FIGS. 1 and 9, the circular ring 25 which defines
the upper end of snow collecting chamber 22 closely fits inside the
open lower end of a rotatable chute 80. Chute 80 is of a generally
conventional design and includes an upwardly extending, U-shaped
discharge trough 82 having a pivotal hood 84 at the top thereof.
Trough 82 is fixedly connected by bolts 85 or the like to a drive
gear ring 86 located generally within opening 26 in cover 11. Drive
gear ring 86 is rotatably constrained in housing 4 by semi-circular
flanges 87 which overlie drive gear ring 86 and prevent it from
being pulled upwardly out of its rotatable support structure in
housing 4. See FIG. 9. The periphery of drive gear ring 86 includes
a set of straight gear teeth 88 for engagement with an improved
crank mechanism or means 90 for rotating drive gear ring 86 and
hence chute 80.
Referring now particularly to FIGS. 4, 9, and 10, crank means 90
includes a longitudinally extending crank handle 92 having a front
end connected to a gear train 94 contained in a U-shaped housing 96
located immediately in back of drive gear ring 86. The rear end of
crank handle 92 is rotatably supported in a bracket 98 located on a
cross piece of handle assembly 8 at the middle thereof. See FIG. 1.
The outer end of crank handle 92 terminates in grip 100 which the
operator, when standing behind handle assembly 8, can reach and
rotate in either direction using either hand. This is true because
crank handle 92 runs straight back from chute 80 to the middle of
handle assembly 8, and not to one side or the other as is typical
in most prior art snowthrowers. Accordingly, an operator who is
either right or left handed can easily reach and operate crank
handle 92.
Turning now to FIGS. 9 and 10, gear train 94 includes a worm 102
which is rotatably mounted on a horizontal cross shaft 104 and is
arranged to have the helical teeth 103 thereof engaged with teeth
88 of drive gear ring 86. An important feature of worm 102 is that
teeth 103 have a relatively shallow lead angle of approximately
12.degree., the lead angle referring to the angle which teeth 103
form relative to a line at right angles to the axis of rotation of
worm 102 as indicated by the angle .beta. in FIG. 9. Intermediate
drive gear 106 is located on the same cross shaft 104 as worm 102
and is integrally formed with worm 102 to one side thereof. A
spacer gear 108, similar to drive gear 106 in shape, is loosely
journalled on shaft 104 on the other side of worm 102. Drive gear
106 and spacer gear 108 are both coupled to a face gear 110 with
spacer gear 108 preventing face gear 110 from cocking during
operation. Face gear 110 has a central circular hub 112 which
extends through the rear wall of housing 96. Hub 112 includes a
recess 114 for receiving therein the front end of crank handle 92
which includes a flattened key portion 116 for nonrotatably
securing crank handle 92 within recess 114. A spring (not shown) is
preferably connected to crank handle 92 to bear against some part
of snowthrower 2, such as bracket 98, in a direction which firmly
biases crank handle 92 into engagement with gear train 94. One
important feature of gear train 94 is that the gear ratios are
chosen to provide at least a two to one speed increases from face
gear 110 to worm 102. The operation of gear train 94 will be
described hereafter.
Turning now to the operation of snowthrower 2, any suitable means,
such as a pull rope or an electric starter, may be provided for
starting engine 10. With the operator standing behind handle
assembly 8, operation of impeller 30 can begin at any time simply
by closing bail 78 against the upper end of handle assembly 8. This
transfers power from engine 10 to impeller 30 to rotate impeller 30
as shown by the direction of the arrows C in FIG. 3. The operator
can then use rotation of impeller 30 to help move snowthrower 2
along the ground. This is done by slightly tipping snowthrower 2
forwardly to bring rubber paddles 32 into engagement with the
ground. Because of the complex curved shape of each paddle 32, one
or more points on at least one paddle 32 are always in engagement
with the ground which serves to help propel snowthrower 2 along.
For example, referring to FIG. 1, the ground can be illustrated as
a line which in the particular position of impeller 30 shown
therein is being contacted by the lowermost paddle 32 at the two
points of contact labeled Y. As the rotation of impeller 30
continues in the direction of arrows C, contact points Y will move
closer to one another until the lowermost paddle 32 is contacting
the ground only at the very midpoint of the curved central
snowthrowing section 34. However, before this midpoint departs from
its engagement with the ground, the outermost end sections 36 of
the upper paddle 32 have already contacted the ground, so that a
continuous self-propelling action is exhibited by impeller 30,
rather than the slapping type self-propelling action exhibited by
snowthrowers having straight paddles. When or if a self-propelling
action is not desired, the operator only needs to let snowthrower 2
rest back on its wheels 6 in which case paddles 32 will be out of
engagement with the ground.
As impeller 30 rotates, the first parts of each paddle 32 which
contact any given unit volume of snow immediately in front of
impeller 30 are the outer end sections 36 of paddle 32. These
sections tend to bite into the snow and move the relatively small
volume of snow lying outboard of central section 34 inwardly toward
central section 34. As the rotation continues and paddle 32 bites
deeper into the snow, the central section 34 then begins to engage
not only the snow moving inwardly from end section 36, but also the
other and major volume of snow immediately in front of the central
sections 34 which end section 36 cannot reach. Central section 34
then scoops up all of this snow and carries it rearwardly against
the arcuate lower portion 19 of rear wall 18. This lower portion 19
confines the snow on paddle 32 until the tangent point between the
rear wall and paddle 32 is reached, i.e., the point at which paddle
32 is adjacent the lower edge 27 of collecting chamber 22. At this
point, the snow on paddle 32 is thrown upwardly directly into the
collecting chamber 22 with collecting chamber 22 having been shaped
to aproximate nicely the size and shape of the inwardly tapered
snow stream as it leaves the central section of paddle 32, i.e., a
stream which decreases in width as it rises vertically. The snow is
thrown upwardly through collecting chamber 22 and the circular ring
25 which defines the top thereof into rotatable chute 80. The snow
can then be thrown in various different directions depending upon
how chute 80 has been turned.
Impeller 30 and the combination of impeller 30 and snow collecting
chamber 22 have numerous advantages as follows:
1. The shape of impeller 30 along with the shape and placement of
collecting chamber 22 yield a single stage snowthrower 2 having
performance characteristics which begin to approach the performance
of much larger two-stage snowthrowers. In this regard, Applicants
believe that the shape of central snowthrowing section 30,
including its slight amount of forward facing, is more efficient
than prior art straight paddle impellers in collecting and throwing
snow, i.e., the snow appears to be firmly cupped and held by
central section 34 until it is released into chamber 22 with less
spillage of snow on the paddle. Moveover, impeller 30 according to
this invention scoops and removes the snow in a snow path which by
and large does not have a great number of turns or changes in
direction. In addition, collecting chamber 22 is sized and shaped
to coincide with the size and shape of the snow stream from central
section 34 and begins at the tangent point where impeller 30
releases the snow. This configuration of impeller 30 and chamber 22
thus removes the snow with a minimum of disturbance and without
providing sharp and inefficient changes in direction or surfaces on
which the snow can get hung up. In addition, collecting chamber 22
is open in front up to the level of circular ring 25 such that
collecting chamber 22 will not plug even with wet and heavy snow.
All these factors are believed to have contributed in varying
degrees to a snowthrower which exhibits substantial performance
improvements over more conventional single-stage snowthrowers 2.
Impeller 30 has also had the various sections thereof proportioned
in such way so that the snow is handled with very little forward
spit or dribbling. Unlike many snowthrowers of the prior art which
have relatively long auger sections in relation to a short central
impeller. Applicants have discovered that the impeller should be
shaped exactly the reverse, i.e., having a relatively long central
section 34 with short end sections 36 that function as augers. This
relationship has been described in two ways earlier in this
application, namely by describing the physical parameters for the
length of central snowthrowing section 34 in relation to end
sections 36 and also by noting that central snowthrowing section 34
engages and removes a larger volume of snow than the combined
volumes of snow moving inwardly from end section 36. Accordingly,
such an impeller 30 does not overfeed snow from the end sections 36
to central section 34, i.e. central section 34 can handle and
remove all the snow it receives from the end sections 37 with a
minimum of snow being recirculated. Accordingly, the aesthetic
appearance of snowthrower 2 in operation, which may be very
important to some purchasers, is improved with much less forward
snow spit or dribbling coming from snowthrower 2. Whatever snow
does escape upwardly from the end sections 36 before feeding onto
the central section 34 is quickly knocked down by two downwardly
directed ledges or kickers 120 located on the upper portion 20 of
rear wall 18 on either side of snow collecting chamber 22.
3. The use of a flexible material bent into and maintained in the
shape of paddle 32 appears to contribute to a number of advantages.
For one thing, when snowthrower 2 is tipped forwardly and paddles
32 are able to engage the ground a continuous self-propelling
action is exhibited by the snowthrower. In addition, the rubber
material which paddles 32 are made can be picked from a relatively
softer rubber material since they will become more rigid by the
very act of bending them into shape. When these paddles wear, they
appear to extrude a small lip off the rear thereof as shown in one
of the paddles illustrated in FIG. 6. Applicants have discovered
that paddles 32 shaped as illustrated and described herein appear
to maintain their ability to throw snow at longer hours of
operation than more conventionally shaped flat, radial paddles. It
is believed this is due to the use of a flexible material having
the concave shape for central section 34 which acts as a rigid cup
in scooping and throwing the snow such that its ability to do so
does not degrade as much even when the clearance between the
central section 34 and the arcuate lower portion 19 of rear wall 18
increases. In addition, it is believed that the use of a softer
rubber material in paddles 32 also contributes to this long life.
While the presence of the lip at the rear of paddles 32 which is
extruded during wear might maintain the clearance between the tip
of paddle 32 and the arcuate lower portion 19 of rear wall 18 at a
more constant value, it is believed that this would be relatively
minor in contributing to the ability of paddles 32 to throw snow
more effectively at longer hours of operation, at least minor
compared to the presumed major factors of the shape itself along
with the use of a softer rubber material.
Accoringly, impeller 30 according to this invention yields many
advantages as noted above. Various modifications to this invention
would be apparent to those skilled in the art. For example, while
impeller 30 is most effectively used with an inverted funnel-shaped
collecting chamber 22 of the type shown, it would not necessarily
have to be used in conjunction with such a collecting chamber 22
for snowthrower 2 to have improved performance characteristics. For
example, it could be used on even existing single stage
snowthrowers such as the Toro S-200 or S-620 by mounting impeller
30 in place of the currently existing impeller. Even with such a
substitution, the improved construction of snowthrower of impeller
30 appears to yield improved results in terms of the height of the
thrown snow, the cohesiveness of the snow stream, less forward snow
spit or dribbling and improved performance at higher hours of
operation of the paddle.
In addition, the specific crank means 90 disclosed in this
application for rotating chute 80 would also appear to have
definite and distinct advantages over similar prior art
arrangements. These advantages relate primarily to the fact the
gear train 94 provides a means for speeding up rotation of chute 80
in relation to how many turns is required on crank handle 92, all
with a gear train 94 that is not susceptible to reverse rotation
due to the snow load on chute 80. In this invention, the lead angle
.beta. on worm 102 is sufficiently small so that it approximates a
self-locking arrangement, i.e., one where a torque force on the
drive gear ring 86 is not able to cause reverse rotation of worm
102 because the lead angle will not allow this. However, to
compensate for the tendency of such a worm 102 to rotate drive gear
ring 86 slowly, Applicants have utilized the speed increasing face
gear 110, which effects at least a two-to-one speed increase from
crank handle 92 to worm 102. Moreover, the entire arrangement has
now been designed to come off directly to the rear from rotatable
chute 80 so that grip 100 on crank handle 92 is situated at the
midpoint of handle assembly 8. This allows ambidextrous operation
in an easy fashion and does not require the operator to reach to
one side or the other of snowthrower 2 to operate crank handle 92.
All these improved characteristics can be found in the crank means
90 and can be used in a snowthrower 2 of any design as long as that
snowthrower utilizes a rotatable chute arrangement 80 of the type
shown herein.
There are other modifications which will be apparent to those
skilled in the art. Accordingly, the scope of this invention will
be limited only by the appended claims.
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