Combined cutter and bypass for propeller

A motor-driven marine propeller is disclosed for propelling a marine vessel. The propeller includes a hub member driven by the motor and a can member disposed coaxially relative to the hub member the can member having a fore and an aft end. The hub member and the can member define therebetween an annular port for the passage therethrough of a portion of the exhaust generated by the motor. Supports extend between the hub member and the can member for supporting the can member coaxially relative to the hub member and a plurality of blades are secured to and extend from the can member with each of the blades being equidistantly spaced relative to each other. Each of the blades defines a leading and a trailing surface such that the propeller rotates in a direction from the trailing towards the leading surface in normal forward motion. A plurality of notches are defined by the fore end of the can member and each of the notches is disposed adjacent to a trailing surface of an adjacent blade such that the notches cut through filamentary material entangled around the propeller and reduce the generation of eddies during rotation of the propeller.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a motor-driven marine propeller for propelling a 
marine vessel or the like. More specifically, this invention relates to a 
marine propeller having a can for the passage therethrough of exhaust 
generated by the motor. 
2. Information Disclosure Statement 
Can-type propellers have been used extensively for propelling high speed 
motor boats, particularly boats used in bass fishing tournaments. Can-type 
propellers include a central hub driven by an outboard motor. A can 
disposed coaxially with the central hub is connected to the hub by 
radially extending webs and the exhaust generated by the motor is directed 
through the annular port defined by the hub and the can. A plurality of 
blades, usually three, extend substantially radially from the can such 
that as the hub is driven by the motor, rotational movement is transmitted 
to the can and attached blades by means of the radially extending webs. 
While some cans are essentially cylindrical, the aft end of the can on some 
can propellers is flared ouwardly on the outer can surface or the inner 
can surface or both such that as the propeller rotates for providing 
forward motion to the boat there exists a tendency to decrease pressure in 
the water behind the aft end of the can thereby assisting the scavenging 
of gaseous exhaust from the fore to the aft end of the can. 
However, with the aforementioned prior art propellers, as the blades rotate 
in the water, eddies are generated in the vicinity of the trailing 
surfaces of the blades. Consequently, proposals have been developed in 
which a portion of the exhaust is directed through holes in the fore end 
of the can such that this portion of the exhaust will flow along the 
trailing surface of the blades and assist the smooth flow of water from 
the fore to the aft end of the can. 
An example of the aforementioned proposal in which a portion of the exhaust 
is bypassed is disclosed in U.S. Pat. No. 3,788,267 to Strong. 
U.S. Pat. No. 3,788,267 teaches that cavitation most often occurs in high 
speed propellers and discusses the effects of polishing the blades. 
However, this disclosure emphasizes that due to mass production adequate 
polishing is not always possible. Part of the exhaust is permitted to pass 
through axially spaced holes thereby enabling the inhibition of cavitation 
bubbles on the surfaces of the blades. 
Another problem encountered by high speed motor boats is the entanglement 
of water weeds around the propeller. 
U.S. Pat. No. 4,080,099 to Snyder teaches a plurality of weedcutting 
fingers radially offset from the propeller shaft for cutting entangled 
weeds. 
Although the prior art propellers have, to a degree, avoided cavitation 
bubbles, and cutting devices have been proposed for cutting entangled 
weeds and fishline and the like, the present invention not only combines 
these characteristics but also provides an improved configuration which 
enhances performance and efficiently cuts through entangling weeds. 
Therefore, it is a primary object of this invention to provide a marine 
propeller that overcomes the aforementioned inadequacies of the prior art 
devices and provides an improvement which significantly contributes to the 
overall performance of a marine propeller or the like. 
Another object of the present invention is the provision of a marine 
propeller having a plurality of notches defined by the fore end of the can 
member, each of the notches being disposed adjacent to a trailing surface 
of an adjacent blade thereby enhancing relief of exhaust gas and assisting 
the smooth flow of water from the fore to the aft end of the can member. 
Another object of the present invention is the provision of a marine 
propeller in which each of the notches is triangular in configuration with 
the triangular configuration being right angled to include a first edge 
which extends substantially parallel to the axis of rotation of the 
propeller for cutting through filamentary material entangled around the 
propeller. 
Another object of an alternate embodiment the present invention is the 
provision of a marine propeller in which each of the notches is in the 
form of a slot substantially parallel to the root portion of the adjacent 
blade for cutting through filamentary material entangled around the 
propeller. 
Another object of the present invention is the provision of a marine 
propeller in which the apex of each of the plurality of notches enables 
part of the exhaust to pass along the trailing surface of an adjacent 
blade rearwardly across the outer surface of the can member towards the 
aft end of the can member and towards the leading surface of an 
approaching blade during rotation of the propeller thereby reducing the 
generation of eddies and assisting in the displacement of fluid in front 
of each leading blade surface of the propeller. 
Another object of the present invention is the provision of a marine 
propeller in which the fore end of the can member defines an annular lip 
which is of reduced thickness relative to the thickness of the remainder 
of the can member such that the annular lip cooperates with an exhaust 
conduit of the motor such that a portion of the exhaust is conducted past 
the lip and through the annular port defined by the hub and the can 
member. 
The foregoing has outlined some of the more pertinent objects of the 
present invention. These objects should be construed to be merely 
illustrative of some of the more prominent features and applications of 
the invention. Many other beneficial results can be obtained by applying 
the disclosed invention in a different manner or modifying the invention 
within the scope of the disclosure. Particularly, with regard to the use 
of the invention disclosed herein, it should not be construed as being 
limited to propellers for marine application, but should include any 
propeller rotating within a fluid. More particularly, the term "marine 
propeller" should not be taken to limiting the use of such propeller for 
propelling boats through the sea or ocean but should include propellers 
for use in fresh water lakes, rivers and the like. 
SUMMARY OF THE INVENTION 
The marine propeller of the present invention is defined by the appended 
claims with a specific embodiment shown in the attached drawings. For the 
purpose of summarizing the invention, the invention relates to a marine 
propeller for propelling a marine vessel. The propeller includes a hub 
member driven by the motor and a can member disposed coaxially relative to 
the hub member, the can member having a fore and an aft end. The hub 
member and the can member define therebetween an annular port for the 
passage therethrough of a portion of the exhaust generated by the motor. A 
support means extends between the hub member and the can member for 
supporting the can member coaxially relative to the hub member and a 
plurality of blades are secured to and extend from the can member with 
each blade being equidistantly spaced relative to each other. A root 
portion of each blade is disposed adjacent to the can member and extends 
substantially from the fore to the aft end of the can member. Each of the 
blades defines a leading and a trailing surface such that the propeller 
rotates in a direction from the trailing towards the leading surface in 
normal forward motion. A plurality of notches are defined by the fore end 
of the can member and each of the notches of the plurality of notches is 
disposed adjacent to a trailing surface of an adjacent blade. 
In a more specific embodiment of the present invention, the hub member 
includes a first hub sleeve which defines a splined bore, and a second 
sleeve disposed coaxially relative to the first hub sleeve such that the 
first hub sleeve extends through the second hub sleeve. An elastomeric 
bushing extends between and is disposed coaxially relative to the sleeves 
such that the bushing yieldably transmits rotational movement of the first 
hub sleeve to the second hub sleeve. 
The can member is substantially cylindrical in configuration and may be 
flared outwardly towards the aft end of the can member for assisting the 
flow of exhaust gas from the fore towards the aft end of the can member, 
thereby generating a vortex flox configuration when the propeller is 
rotated. The fore end of the can member defines an annular lip which is of 
reduced thickness relative to the thickness of the remainder of the can 
member such that the annular lip cooperates with an exhaust conduit of the 
motor so that a portion of the exhaust is conducted past the lip and 
through the annular port. 
The support means extends between the hub member and the can member and 
includes a plurality of webs with each web extending radially from the hub 
member towards the can member. Each web is secured to the can member in 
the preferred embodiment adjacent to a fore end of the root portion of a 
blade such that the number of webs corresponds to the number of blades. 
In a preferred embodiment of the present invention, the propeller includes 
a first, second and third blade, each of the blades having substantially 
the same configuration and dimensions and in which each of the blades 
extends outwardly and rearwardly away from the can member in a direction 
from the fore to the aft end of the can member such that the blades extend 
rearwardly from the can member past the aft end of the can member. 
Each notch of the plurality of notches is formed in the can member with 
each notch being positioned in the fore end of the can member 
substantially adjacent to the trailing surface of an adjacent blade. The 
fore end of the can member further includes a rim edge wherein each notch 
of the plurality of notches extends from the rim edge into the can member. 
Each of the notches in the fore end of the can member in a preferred 
embodiment is located adjacent to the trailing surface of a blade and is 
substantially triangular in configuration. The triangular configuration is 
right angled with the hypotenuse extending substantially parallel to the 
root portion of the adjacent blade. Each notch defines a first edge which 
extends substantially parallel to the axis of rotation of the propeller 
for cutting through filamentary material entangled around the propeller. 
Furthermore, the apex of each of the notches enables part of the exhaust 
to pass along the trailing surface of the adjacent blade rearwardly across 
the outer surface of the can member towards the aft end of the can member 
and towards the leading surface of an approaching blade during rotation of 
the propeller in normal forward motion, thereby reducing the generation of 
eddies and assisting in the displacement of fluid in front of each leading 
surface of the propeller. 
In an alternative embodiment, each of the notches is substantially in the 
form of a slot located adjacent to the trailing edge of a blade and 
substantially parallel to the root portion of the adjacent blade. The slot 
may have a flared opening at the fore end of the can. The leading edge of 
the slot is substantially parallel to the root portion of the adjacent 
blade, while a first segment of the trailing edge is substantially 
parallel to the leading edge and joined thereto at an apex of the slot. 
The remainder of the trailing edge of the slot may continue to the fore 
end of the can in a direction substantially parallel to the leading edge 
of the slot, or the remainder of the trailing edge of the slot may form a 
second segment substantially parallel to the axis of rotation of the 
propeller, thus producing a flared opening in the fore end of the can. In 
this alternative embodiment, the first segment of the trailing edge of the 
slot, which is substantially parallel to the leading edge of the slot, is 
preferably approximately one-half the length of the leading edge of the 
slot, and the flared opening has a dimension roughly one half the length 
of the leading edge of the slot. 
The foregoing has outlined rather broadly the more pertinent and important 
features of the present invention in order that the detailed description 
that follows may be better understood so that the present contribution to 
the art can be more fully appreciated. Additionally, features of the 
inventions will be described hereinafter which form the subject of the 
claims of the invention. It should be appreciated by those skilled in the 
art that the conception and the specific embodiment disclosed may be 
readily utilized as a basis for modifying or designing other devices for 
carrying out the same purposes of the present invention. It should also be 
realized by those skilled in the art that such equivalent constructions do 
not depart from the spirit and scope of the invention as set forth in the 
appended claims.

Similar reference characters refer to similar parts throughout the several 
views of the drawings. 
DETAILED DESCRIPTION 
FIG. 1 is a side elevational view of a marine propeller generally 
designated 10 for propelling marine vessel. The propeller 10 includes a 
hub member generally designated 12 as shown in FIGS. 2 and 3 driven by a 
motor. A can member 14 is disposed coaxially relative to the hub member 
12, the can member 14 having a fore and an aft end 16 and 18 respectively. 
The hub member 12 and the can member 14 define therebetween an annular 
port 20 shown more particularly with reference to FIGS. 2 and 3 for the 
passage therethrough of a portion of the exhaust generated by the motor. 
Support means generally designated 22 extend between the hub member 12 and 
the can member 14 for supporting the can member 14 coaxially relative to 
the hub member 12. A plurality of blades 24, 25, and 26 are secured to and 
extend from the can member 14 with each of the blades 24, 25 and 26 being 
equidistantly spaced relative to each other. A root portion 28, 29 and 30 
of each blade 24, 25 and 26 respectively is disposed adjacent to the can 
member 14 such that the root portions 28-30 extend substantially from the 
fore end 16 to the aft end 18 respectively of the can member 14. 
FIG. 3 shows the propeller 10 viewed from the aft end 18 of the can member 
14 and shows the blades 24-26 extending from the can member 14. 
More specifically, as shown particularly with reference to FIG. 3, the hub 
member 12 also includes a first hub sleeve 32 which defines a splined bore 
34. A second hub sleeve 36 is disposed coaxially relative to the first hub 
sleeve 32 such that the first hub sleeve 32 extends through the second hub 
sleeve 36. An elastomeric bushing 38 extends between and is disposed 
coaxially relative to the sleeves 32 and 36 such that the bushing 38 
yieldably transmits rotational movement of the first hub sleeve 32 to the 
second hub sleve 36. 
As shown particularly in FIG. 1, the can member 14 is substantially 
cylindrical in configuration with the aft end 18 of the can member 14 
including an outward flare 40 for assisting the flow of exhaust from the 
fore towards the aft end 16 and 18 respectively of the can member 14. The 
flared aft end 18 of the can member 14 generates a vortex configuration 
within the water when the propeller 10 is rotated, and the resulting low 
pressure region tends to enhance scavenging of the exhaust. The fore end 
16 of the can member 14 defines a annualar lip 42 which is of reduced wall 
thickness relative to the thickness of the remainder of the can member 14. 
The annular lip 42 cooperates with an exhaust conduit (not shown) of the 
motor such that a portion of the exhaust is conducted past the lip 42 and 
through the annular port 20. 
As shown with reference to FIGS. 2 and 3, the support means 22 includes a 
plurality of webs 44, 45 and 46 with each web extending radially from the 
hub member 12 towards the can member 14. Each of the webs 44-46 is secured 
to the can member 14 adjacent to the fore end 16 of each of the root 
portions 28 and 30 respectively such that the number of webs 44-46 
corresponds to the number of blades 24-26. 
Preferably, the propeller 10 includes a first, second and third blade 24, 
25 and 26 with each of the blades 24-26 having substantially the same 
configuration and dimensions. As shown with reference to FIG. 1, each of 
blades 24-26 extends outwardly and rearwardly away from the can member 14 
in a direction from the fore to the aft end 16 and 18 respectively of the 
can member 14 such that the blades 24-26 extend rearwardly from the can 
member 14 past the aft end 18 of the can member 14 with each of the blades 
24-26 extending from the external surface 52 of the can member 14. 
An important feature of the present invention includes a plurality of 
V-shaped or triangular notches generally designated 54, 55 and 56 defined 
by the can member 14 towards the fore end 16 of the can member 14. These 
notches 54-56 are equidistantly spaced around the fore end 16 of the can 
member 14. Each of the notches 54-56 are identical in configuration and 
dimensions and include an edge 58, 59 and 60 respectively disposed 
substantially parallel to the axis of rotation AR of the propeller 10 such 
that when the propeller 10 rotates, the edges 58-60 tend to cut through 
filamentary material entangled around the can member 14. 
The triangular shaped notches 54-56 as shown in FIG. 2 also include sides 
62, 63 and 64 respectively which constitute the hypotenuse of the 
triangular configuration. The sides 62-64 are disposed substantially 
parallel to and adjacent to the trailing surfaces 66, 67 and 68 
respectively of the blades 24-26 as shown in FIGS. 1 and 2. As shown in 
FIG. 1, the side 63 of the notch 55 is disposed adjacent to the trailing 
surface 67 of the blade 25. Not only do the edges 58-60 of the triangular 
shaped notches 54-56 assist in cutting through entangled filamentary 
material, but also these notches 54-56 which correspond in number to the 
number of blades of the propeller permit passage of part of the exhaust 
from the annular port 20 towards the respective apices 70, 71 and 72 of 
the notches 54-56 and onwards towards the trailing surfaces 66-68 of the 
blades 24-26. This part of the exhaust follows the external surface 52 of 
the can member 14 and is approached by an adjacent blade as the blades 
24-26 rotate. Therefore, part of the exhaust flows from the annular port 
20 through the notches 54-56 towards the apices 70-72 along the trailing 
surfaces 66-68 across the external surface 52 of the can member 14 and 
toward leading surfaces 74, 75 and 76 shown in FIG. 3 of the blades 24-26 
respectively. This flow of part of the exhaust tends to inhibit the 
formation of eddies adjacent to the external surface 52 of the can member 
14 thereby increasing the free flow and displacement of fluid ahead of the 
leading surfaces 74-76 of each blades 24-26 as the blades rotate. This 
feature in combination with the outward flare 40 at the aft end 18 of the 
can member 14 reduces the tendency to cavitation in the vicinity of the 
propeller 10 and therefore enhances the "hole shot" or "standing start" 
performance of the propeller. 
An alternative embodiment of the present invention is shown in FIGS. 4 and 
5 of the drawings. This alternative embodiment differs from that design 
described above only in the shape of the notches which are located at the 
fore end of the can adjacent to the trailing surface of each blade. As 
shown particularly in FIG. 4, the notch of the alternative embodiment is 
in the form of a slot genrally designated 80 which has a trailing edge 86 
comprising a first segment 104 and a second segment 110. Slot 80 is also 
defined by leading edge 92 joined to the first segment 104 at the apex 98. 
Leading edge 92 of slot 80 (and of each of the plurality of slots) is 
substantially parallel to the root portion of the adjacent blade (not 
visible in FIG. 4). The trailing edge 86 of slot 80 may be substantially 
parallel to leading edge 92 and to the root portion of the adjacent blade, 
or the trailing edge 86 may have a first segment 104 as shown in FIG. 4 
which is substantially parallel to leading edge 92 and roughly half the 
length of leading edge 92. Trailing edge 86 may also comprise a second 
segment 110 which is substantially parallel to the axis of rotation AR of 
the propeller, thus forming a slot 80 with a flared opening at the fore 
end 16 of can member 14. 
FIG. 5 shows the front elevational view of the alternative embodiment with 
the three flared openings of slots 78, 80 and 82 respectively visible on 
the fore end 16 of can member 14 adjacent to the trailing surfaces of the 
blades of the three-bladed propeller shown for purposes of illustration. 
Also visible in this view is the forward portion of the slot leading edges 
90, 92 and 94 respectively. Notches cut in the form of the slots as 
described in FIGS. 4 and 5 have been found to be quite effective both in 
the relief of the motor exhaust and reduction of cavitation problems as 
well as in the cutting of filamentary material such as aquatic plants and 
fishing line which may occasionally become entangled in the propeller. 
In operation of the propeller according to the present invention, when the 
propeller is rotated in a counter clockwise direction when viewed as shown 
in FIGS. 2 and 5, the notches not only serve to cut entangled filamentary 
material from around the can member but also serve the purpose of reducing 
cavitation in the vicinity of the propeller. 
The present invention provides a propeller which meets all the optimum 
characteristics required particularly by competition bass fishermen and 
also provides an improved stability and controlability of the craft to 
which such propeller is fitted. 
The present disclosure includes that contained in the appended claims as 
well as that of the foregoing description. Although this invention has 
been described in its preferred form with a certain degree of 
particularity, it is understood that the present disclosure of the 
preferred form has been made only by way of example and that numerous 
changes in the details of construction and the combination and arrangement 
of parts may be resorted to without departing from the spirit and scope of 
the invention.