Water jet propulsion unit

A water jet propulsion unit for a watercraft including a separator for extracting a portion of the water pumped by the jet propulsion unit for another purpose while removing foreign particles from the separated water and returning them to the jet propulsion unit to avoid clogging of the external water supply.

BACKGROUND OF THE INVENTION 
This invention relates to a water jet propulsion unit and more particularly 
to an improved arrangement for picking off a portion of the water pumped 
by the jet propulsion unit and using it for another purpose and separating 
foreign articles from the picked-off water and returning them to the jet 
propulsion unit. 
Water jet propulsion units have a number of advantages over more 
conventional propeller type systems. For example, it is possible to 
operate the watercraft powered by the jet propulsion unit in much 
shallower water than with conventional propellers. In addition, a portion 
of the water which is circulated by the impeller of the jet propulsion 
unit can be used for a variety of other purposes. For example, this water 
may be delivered to the cooling jacket of the engine for circulation 
therethrough. Alternatively, the diverted water can be employed to operate 
a venturi type of pump for pumping water from the bilge of the watercraft. 
In connection with these uses of the diverted water, there is, however, a 
problem. Because of the fact that the jet propulsion unit can be operated 
in shallow water, there is a likelihood that foreign particles may be 
pumped through the jet propulsion unit. This is true even if a strainer is 
utilized for the main portion of the jet propulsion unit. Such strainers 
are employed only to remove extremely coarse articles since smaller 
particles can present no basic problem to the operation of the jet 
propulsion unit. 
If, however, these smaller particles are passed into the conduit that 
supplies the tapped off water, they can obstruct its flow. If the water is 
used for the cooling system of the engine, this will mean that the engine 
can be inadequately cooled. Alternatively, if the drawn off water is 
utilized for a venturi pump, then the venturi pump can itself become 
clogged. 
It has been proposed to avoid these difficulties by providing a strainer in 
the drawn off water conduit. However, the strainer itself can become 
clogged and the same results will occur unless the strainer is serviced 
frequently. 
It is, therefore, a principal object of this invention to provide an 
improved arrangement for separating foreign particles from the water drawn 
off of a jet propulsion unit. 
It is a further object of this invention to provide a separator for such 
water wherein the removed particles will be returned and disposed of 
through the jet propulsion unit. 
It is a further object of the invention to provide a separator for such 
water that will not require servicing. 
SUMMARY OF THE INVENTION 
This invention is adapted to be embodied in a water jet propulsion unit for 
a watercraft that comprises a water inlet opening through which water may 
be drawn from the body of water in which the watercraft is operating, an 
impeller portion containing an impeller for pumping the water and a 
discharge nozzle for discharging the water pumped by the impeller for 
propelling the watercraft. A separator device is provided for separating 
particles from the water and for drawing off a portion of the water pumped 
by the impeller. This separator device includes an inlet that communicates 
the separator device with the jet propulsion unit for receiving a portion 
of the water pumped by the impeller and for returning the separated 
particles to the jet propulsion unit and an outlet for receiving the 
separated water for a purpose other than propulsion of the watercraft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
Referring now in detail to the drawings and initially to FIG. 1, a small 
jet propelled watercraft constructed in accordance with an embodiment of 
the invention is identified generally by the reference numeral 11. It is 
to be understood that the watercraft 11 is exemplary only of one form of 
watercraft in which the invention may be practiced. However, it is to be 
understood that the invention does have particular utility in conjunction 
with jet propelled watercraft. 
Watercraft 11 is comprised of a hull assembly, indicated generally by the 
reference numeral 12, and which may be formed from any suitable material 
such as a molded fiberglass reinforced resin or the like. The hull 12 
defines a forwardly positioned engine compartment 13, a rearwardly 
positioned rider's area including a seat 14 and a tunnel 15 that is 
positioned beneath the seat 14 and which is separated from the engine 
compartment 13 by means of a bulkhead 16. In the illustrated embodiment, 
the seat 14 is adapted to accommodate a single rider seated in straddle 
fashion. 
An internal combustion engine, indicated generally by the reference numeral 
17, is provided in the engine compartment 13 forwardly of the bulkhead. 
The engine 17 may be accessible for service by removal of a hatch cover 18 
which is positioned forwardly of the seat 14. The engine 17 in the 
illustrated embodiment is of the two cycle crankcase compression type 
having two cylinders which drive a crankshaft 19 in a well known manner. 
This engine 17 is mounted within the engine compartment 13 on a pair of 
engine mounts 21 in a well known manner. 
A fuel tank 22 is positioned in the engine compartment 13 forwardly of the 
engine 17 and supplies fuel to the charge forming system of the engine. 
The crankshaft 19 drives an elastic coupling 23 which, in turn, is coupled 
to an impeller shaft 24 of a jet propulsion unit, indicated generally by 
the reference numeral 25, and which jet propulsion unit is mounted in the 
tunnel 15 to the rear of the bulkhead 16. The impeller shaft 24 extends 
through the bulkhead 16 to the coupling 23. 
The jet propulsion unit 25 is comprised of a water inlet portion 26 which 
defines a water inlet duct 27 through which water may be drawn from the 
body of water in which the watercraft is operating. The water inlet duct 
27 may be formed as a portion of the hull 12. 
Referring now additionally and primarily to FIG. 2, the jet propulsion unit 
25 includes in addition to the water inlet portion 27, an impeller housing 
portion 28 in which an impeller 31 is journaled, in a manner to be 
described. The impeller 31 has a forwardly extending portion 32 which is 
received around and journals the impeller shaft 24 in a suitable manner. 
A flange 33 of the impeller housing 28 interconnects the impeller housing 
28 to a further stator housing 34 which has a pair of peripheral flanges 
35 and 36. A nacelle 37 is formed integrally with the housing 34 and has a 
plurality of straightening vanes 38 which receive the water pumped by the 
impeller 31 and cause it to flow rearwardly in an axial direction. The 
nacelle 37 supports the rear end of the impeller shaft 24 on a pair of 
bearings 39 with a seal 41 being positioned at the forward end of the 
nacelle 37. 
The water pumped past the straightening vanes 38 is discharged into a 
discharge nozzle portion 42 that has a flange 43 that is matingly engaged 
with the flange 36 of the straightening vane portion 34. Locating pins 44 
may be positioned between the respective housings 28, 34 and 42 for 
maintaining axial alignment and the desired circumferential location. 
The discharge nozzle portion 42 carries an extension 45 of the nacelle 37 
and which itself has straightening vanes 46. These straightening vanes 
also cooperate with further straightening vanes 47 which may be formed in 
the discharge nozzle portion forwardly of its exit opening 48. 
A steering nozzle 49 is pivotally supported at the end of the discharge 
nozzle portion 42 adjacent the opening 48 on vertically extending pivot 
pins 51. The steering nozzle 49 is coupled to a handlebar assembly 52 
(FIG. 1) carried by a mast 53 at the forward portion of the seat 14 and 
forwardly of the hatch cover 18 so that the watercraft may be steered in a 
well known manner. 
The construction of the watercraft 11 and the jet propulsion unit 25 as 
thus far described may be considered to be conventional. That is, the 
portion of the watercraft 11 and jet propulsion unit 25 as thus far 
described form no part of the invention but rather the environment in 
which the invention can be practiced. 
In accordance with the invention, a portion of the water pumped by the 
impeller 31 is diverted for any of a plurality of purposes, as will be 
described. This water is diverted to a separator, indicated generally by 
the reference numeral 54, and constructed in accordance with an embodiment 
of the invention. The separator 54 is shown in most detail in FIGS. 3-8, 
although it does appear out of position in FIGS. 1 and 2. 
The water separator 54 has a generally rectangular configuration as viewed 
in side elevation and is formed by an outer housing 55 that has pairs of 
side lugs 56 and 57 which engage bosses 58 formed on the flanges 35 and 36 
of the straightening vane housing 34. These bosses 58 have tapped holes 
and the lugs 56 and 57 have apertures 59 so as to receive threaded 
fasteners (not shown) so as to affix the separator 54 to the jet 
propulsion unit 25. In addition, there is provided an upper boss or recess 
61 in which an opening 62 is formed so as to pass a further threaded 
fastener. In a like manner, a lower cross piece 63 is formed with a 
further opening 64 so as to receive an additional threaded fastener so as 
to complete the securement of the separator 54 to the jet propulsion unit 
25. 
The jet propulsion unit housing portion 34 has a generally cylindrical 
inner surface 65 in which a water diversion opening 66 is formed at a 
point below the rotational axis 60 of the impeller shaft 24 and impeller 
31. It will be noted that the lower wall which defines the opening 66 
extends generally horizontally while the upper wall is tapered upwardly 
and outwardly. 
The separator 54 and particularly its housing 55 defines an internal cavity 
67 which forms in part an opening 68 that registers with the jet 
propulsion unit housing portion opening 66. The opening 68 is defined in 
part by a pair of downwardly inclined lower surfaces 69 and 71 which face 
the opening 66 as shown in FIG. 4. A projection 72 is formed in the face 
of the housing 55 which extends into the jet propulsion unit housing 
opening 66 but which terminates outwardly of the inner surface 65. Also, 
it should be noted that the protrusion 72 is somewhat essentric to the 
shape of the cavity 67. This is because the cavity 67 is disposed somewhat 
eccentrically to the opening 66 in the housing portion 34 so as to cause a 
labyrinthine type of water flow through the housing cavity 67. In 
addition, the forward edge of the projection 72 will tend to obstruct 
large foreign particles from entering into the cavity 67 of the separator 
54. Smaller particles, indicated at 74 may, however, reach the opening and 
try to enter the cavity 67. However, these particles 74 will be separated, 
in a manner to be described, and returned into the jet propulsion unit 25 
in the path shown by the arrow 75 in FIG. 4. 
Vertically within the cavity 67 there are positioned three inclined baffles 
comprised of a lower baffle 76, a middle baffle 77 and an upper baffle 78. 
The lower baffle 76 (FIG. 6) is generally rectangular in configuration and 
does not extend from one end of the cavity 67 to the other but does extend 
substantially across the width of the cavity. The baffle 77 (FIG. 7), on 
the other hand, extends along the width of the cavity 67 but is provided 
with a pair of cut-outs 79 through which water may flow. As may be seen, 
the cut-outs 79 are staggered slightly from each other. 
The width of the baffle 77 is equal to the width of the cavity 67. 
The upper baffle 78 (FIG. 8) extends the full depth of the cavity 67 but 
does not occupy its full width. Hence, it should be readily apparent that 
the baffles 76, 77 and 78 will cause a Labyrinthine flow of water from the 
inlet opening 66 to a discharge nozzle 81 positioned at the upper end 
thereof. Thus, any foreign particles that may be trapped in the water that 
is delivered through the inlet opening 66 will be separated by this flow 
and by gravity. Also, since the volume of the chamber 67 is substantially 
greater than the cross-sectional area of the opening 66, the water flow 
velocity will be relatively slow through it and foreign particles will 
tend not to be swept out of the discharge nozzle 81. 
A flexible conduit 82 delivers the water from which foreign particles have 
been separated to either the cooling jacket of the engine 17 and/or a 
venturi type of pump for pumping water from the bilge of the hull 12. 
Thus, it should be readily apparent that the described construction 
provides water from which all possible obstructing foreign particles could 
have moved to either the engine cooling jacket and/or the venturi jet 
pump. Of course, the foregoing description is that of a preferred 
embodiment of the invention and various changes and modifications may be 
made without departing from the spirit and scope of the invention, as 
defined by the appended claims.