AU655857B2 - Water jet propulsion unit - Google Patents

Description

AUSTRALIA

Patents Act 1990 655-857 COMPLETE SPECIFICATION For a Standard Patent

ORIGINAL

TO BE COMPLETED BY APPLICANT Name of Applicant: Actual Inventor: Address for Service: YAMAHA HATSUDOKI KABUSHIKI KAISHA NOBORU KOBAYASHI WRAY ASSOCIATES, Primary Industry House, 239 Terrace, Perth, Western Australia, 6000.

Adelaide 9t 9 *99 9 Attorney code: WR "WATER JET PROPULSION UNIT" Invention Title: Details of Associated Provisional Applications: Nos: 9* 8 99r *94 4.

99 9 99~ The following statement is a full description of this invention, including the best method of performing it known to me:- 9999 94e9 S4 1 Water Jet Propulsion Unit BACKGROUND OF THE INVENTION This invention relates to a water jet propulsion unit and more particularly to an improved watercraft construction and a propulsion unit therefor and to an improved arrangement for assisting the steering of a watercraft powered by a jet propulsion unit.

The advantages of jet propulsion inits for watercraft are well known. Generally, these units permit the operation of the watercraft in shallower water than more conventional propeller driven craft. In addition, the use of jet propulsion units has a number of other advantages in that they provide a neat configuration for the watercraft, and storage of the watercraft both in the water and out of the water can be facilitated. However, as with conventional watercraft, there are some disadvantages that are existent with jet propelled watercraft.

For example, when the watercraft is left in the water for a long period of time and not utilised, encrustation of elements such as barnacles in the running components of igo the propulsion unit can be a problem. In one form of jet propulsion unit, an outboard motor type of jet propulsion unit is employed that employs rather than a propeller a S jet propulsion unit for achieving watercraft propulsion.

Of course, this type of propulsion unit can easily be tilted up out of the water as can the associated stern drive jet propulsion units in which the jet propulsion unit is mounted on the stern of a watercraft as with conventional propeller driven inboard/outboard drives.

However, the use of such outboard motor type jet propulsion units has the disadvantages common with outboard motors. That is, they provide an unsightly -1i/1appearance for the watercraft, they raise the center of gravity and tend to concentrate a large portion of the weight at the hull of the watercraft and have other disadvantages.

Therefore, it is more desirable if the jet propulsion unit can be mounted in a tunnel formed at the rear of the watercraft hull. This provides not only a neat assembly, but also gives rise to improved construction of the watercraft as a whole by lowering its center of gravity and by moving heavy masses more fdrward in the hull. When the jet propulsion unit is positioned in or beneath the hull, many of the problems as aforenoted will be encountered. That is, the jet propulsion unit will clearly be underwater at all times even when not in use and encrustation can occur. Furthermore, because of its nature and the fact that the jet propulsion unit permits operating in shallow water, it may at times become clogged with ±oreign materials such as seaweed, sand or the like.

When positioned in the tunnel of the watercraft hull, however, servicing is more difficult.

It is, therefore, a principal object of this invention to provide an improved watercraft and jet propulsion unit therefor.

It is a preferred object of this invention to provide a jet ipulsion unit for a watercraft wherein the jet prop..sion unit is positioned within the hull of the :S watercraft but nevertheless can be drained of water even when the watercraft is in the body of water but when it is not being operated.

It is a further preferred object of this invention to provide an improved arrangement which permits the trim adjustment of a jet propulsion unit of this type.

2 1 It s yet a further preferred object of this invention to provide a watercraft and hull arrangement having a jet propulsion unit that is positioned within a tunnel and wherein the jet propulsion unit can be conveniently serviced without necessitating removal from the hull or removal of the hull from the body of water in which the watercraft is operating.

It is known that the steering of a jet propelled watercraft is usually achieved by steering of the discharged nozzle of the jet propulsion unit. This means that the steering is somewhat related to the speed at which water is passing through the jet propulsion unit.

Although this is generally acceptable, there are times when the steering by the jet propulsion unit alone may not be adequate. For example, when travelling at slow speeds or coasting, the jet propulsion unit itself may not provide adequate steering.

It has, therefore, been proposed to employ a separate rudder which can also be used for steering purposes when the jet propulsion unit steering is not fully effective.

However, such rudders can become damaged, particularly when considering the type of shallow water in which jet propelled boats can be operated.

*r It is, therefore, a still further preferred object of this invention to provide an improved steering rudder arrangement for a jet propulsion unit wherein the steering rudder will be protected from damage if underwater obstacles are encountered.

SUMMARY OF THE INVENTION rrr4 A first feature of this invention is adapted to be embodied in a watercraft having a hull which defines a 3 I tunnel at the rear end thereof. A jet propulsion unit is positioned substantially within the tunnel. The jet propulsion unit has a generally downwardly facing water inlet portion, an impeller portion containing an impeller for drawing water through the inlet portion and a discharge nozzle' portion for discharge of water from the impeller portion for powering the watercraft. An engine is supported within the hull and drive means drive the impeller from the engine. In accordance with this feature of the invention, means are provided for pivoting the jet propulsion unit about a generally horizontally extending axis that extends transversely to the longitudinal center line of the watercraft and which is positioned contiguous to the water inlet portion.

Another feature of the invention is adapted to be embodied in a jet propulsion unit for association with the hull of the watercraft for propelling the watercraft through a body of water. The jet propulsion unit has, as described in the previous paragraph, a water inlet portion, an impeller portion, and a discharge nozzle pcrtion. In S accordance with this feature of the invention, means are provided for rotating the jet propulsion unit about a generally horizontally extending axis that extends longitudinally relative to the watercraft to rotate the water inlet portion from a downwardly facing position to an upwardly facing position.

A preferred feature of the invention is also adapted to be embodied in a jet propulsion unit of the type in the two preceding paragraphs. In accordance with this feature of .0 the invention, the jet propulsion unit discharge nozzle S portion is supported for steering movement about a vertically extending steering axis for steering of the *54 watercraft. In addition, a rudder is pivotally supported ~by the discharge nozzle for generating a steering effect when travelling at least at low speeds or coasting. In

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4 '7 accordance with this feature of the invention, the rudder is preferably supported for pivotal movement relative to the nozzle and is held in a submerged position by a biasing spring. However, when an underwater object is struck, the biasing spring can yield and permit the rudder to swing upwardly to avoid damage to it and the jet propulsion unit.

Specifically in accordance with one aspect of the present invention there is provided a jet propulsion unit for association with the hull of a Watercraft for propelling the watercraft through a body of water comprising a housing assembly defining a generally downwardly facing water inlet portion for drawing water from the body of water in which the watercraft is operating, an impeller portion supporting an impeller for rotation for drawing water through said inlet portion and a discharge portion for the discharge of water moved by said impeller for propelling the associated watercraft, and means for rotating at least said water inlet portion of said jet propulsion unit about a longitudinal axis to rotate said water inlet portion from a downwardly facing position.

Preferably said jet propulsion unit includes a longitudinally extending input drive shaft having its axis coincident with said longitudinal axis.

PreferaLly said longitudinal axis of rotation of at least said water inlet portion of said jet propulsion unit is coincident with the axis of rotation of said impeller.

Preferably said jet propulsion unit further includes means for supporting said jet propulsion un",t for pivotal movement of at least said water inlet portion between said or ~downwardly facing position and an elevated position.

Preferably said means for supporting said jet propulsion 77 unit includes means J' pivoting at least said water inlet portion about a ygenerally horizontally extending axis transverse to said longitudinal axis.

Preferably said means for supporting said jet propulsion unit for pivotal movement includes a pair of spaced apart guide rails to provide a path of movement for said jet propulsion unit pivoting about said generally horizontally extending axis.

Preferably said pair of spaced 'apart guide rails are adapted to be fixed to the hull of said watercraft, each said guide rail having a slot receiving a pin affixed to said jet propulsion unit.

Preferably said means for supporting said jet propulsion unit are adapted to support said jet propulsion unit against side thrusts thereon.

Preferably said jet propulsion unit further includes hydraulic motor means for pivoting the jet propulsion unit about the transverse pivotal axis.

*e Preferably said jet propulsion unit further includes '0 0 further motor means for rotating at least said water inlet portion of said jet propulsion unit about said longitudinal axis.

Preferably said longitudinally extending input drive shaft incl.des a universal joint disposed at said horizontally extending axis.

Preferably said discharge portion comprises a nozzle pivotally supported relative to said impeller portion for 0444 •o .steering of the watercraft and further including a rudder affixed to the nozzle for generating a steering effect.

511 Preferably the rudder is movably supported on said nozzle for movement away from an underwater obstacle struck by the unit.

Preferably said jet propulsion means further includes biasing spring means for urging the rudder to its normal position.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevatidnal view of a watercraft constructed in accordance with an embodiment of the invention as floating in the water with portions broken away and shown in section and other portions shown in phantom to show the servicing operation.

Figure 2 is a top plan view of the watercraft showing the access compartment in an open position.

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.fl i 4 '34.4 Figure 3 is a cross sectional view taken through the hull of the watercraft and shows the jet propulsion unit and its driving arrangement.

Figure 4 is an exploded perspective view of the jet propulsion unit and its mounting arrangement.

Figure 5 is a cross sectional view taken along the line of Figure 1.

Figure 6 is a cross sectional View taken along the line 6-6 of Figure 1.

-Figure 7 is a bottom perspective view of the rear portion of the hull with the jet propulsion unit removed.

Figure 8 is an enlarged perspective view of the servicing access shown in its open position.

Figure 9 is ,a-cross sectional view, in part similar to Figure 3, and shows another embodiment of the invention.

Figure 10 is an enlarged side elevational view of the discharge nozzle and steering rudder of this embodiment showing the pivotal movement of the steering rudder when an underwater raQr S 'obstacle is struck.

*1 Figure 11 is a rear elevational view of this embodiment.

Figure 12 is an exploded perspective view of this embodiment.

Figure 13 is a side elevational view, in part similar to Figure 10, showing another embodiment of'the invention.

Figure 14 is a rear elevational view of this embodiment.

Figure 15 is an enlarged exploded perspective view of this embodiment.

6 Figure 16 is a side elevational view, in part similar to Figures 10 and 13, and shows yet another embodiment of the invention.

Figure 17 is a rear elevational view of this embodiment.

Figure 18. is a cross sectional view, in part similar to Figures 3 and 9, showing' another embodiment of the invention.

Figure* 19. is a cross sectional view taken transverse to the plane of Figure 18.

Figure 20 is an enlarged cross sectional view showing how the jet propulsion unit seals with the adjacent portions of the hull in its normal operating condition.

Figure 21 is a' perspective view of the seal for this embodiment.

DETAILED DESCR.IPTION OF THE PREFERR.ED EMBODIMENTS OF THE

INVENTION

5 .i Referring first to Figures 1 and 2, a watercraft constructed 'toot. in accordance with an embodiment of the invention and powered by jet propulsion unit constructed in accordance with certain features of the invention is identified by the reference numeral 21., It should be understood that the hull and cabin 0 configuration to be described is only one og many with which the invention can be practiced. The watercraft 21 is comprised of a hull assembl~y that includes a lower or main hull portion 22 4.,closed by a deck 23. The hull portion 22 and deck portion 23 may be conveniently formed from molded fiberglass reinforced resins.

t-7- Of course, other materials can be utilized as should be readily apparent.

The hull and deck 22 and 23 define a forwardly positioned cabin 24 that is accessible through a hatch and hatch closure from an open rider's compartment 26 formed rearwardly thereof.

Positioned within the open rider's area 26 are a pair of forwardly disposed seats 27, one of which is designed to accommodate the operator. A steering -wheel 28 is positioned forwardly of this one seat for steering of the watercraft, in a manner which will be described.

The underside of the hull 22 is formed with a central, rearwardly disposed tunnel .portion 29 in which a jet propulsion unit, indicated generally by the reference numeral 31 is positioned in a manner to.be..described. An engine compartment 32 is positioned forwardly thereof and contains an internal combustion engine 33 for driving the jet propulsion unit 31 in a manner to be described. A pair of rear decks or seats 34 are provide on opposite sides of the tunnel 29 an engine compartment 9* 32.

s t Referring now primarily to Figures 1, 3 and 5, the engine .*1 compartment 32 is formed in part by a pair of vertically extending side walls 35 that depend from a decks or seals 34 of the rider's compartment 26. A pair of forwardly disposed embossments 37 are formed therein so as'to provide a means of attachment of the forward portion of the engine 33 thereto. The ut rear end of the engine compartment 33 is defined by a vertically extending bulkhead 38 that separates the engine compartment 32 -8from the tunnel 29. A bearing plate 39 is affixed thereto that has a forwardly extending portion 41 to which rear engine mounts 42 'are affixed for completing the mounting of the engine 33 within the engine compartment 32. The engine compartment is further completed and enclosed by means of a removable engine cover 43 as best shown in Figure 5, which can be conveniently put in place and removed so as to afford access to the engine 33.

Referring now in detail primarily to Figures 3 and 4, it will be noted that the jet propulsion unit 31 is comprised primarily of an outer housing 41 which may be of a unitary or fabricated construction. The outer housing 44 defines a water .inlet portion 45 that terminates in a downwardly extending water inlet opening 46 that is defined by a peripheral flange 47. In Sthenormal operating condition, the opening 46 and a portion of the inlet 44 is disposed beneath the normal operating water level.

Rearwardly of the inlet portion 45, the housing 44 defines an impeller housing portion 48 in which an impeller 49 (Figure is supported for rotation in a suitable manner. The impeller 49 is affixed to an impeller shaft 51 which, in turn, extends forwardly through the water inlet portion 45 and through a cylindrical projection 52 of the housing.44. A pair of water S. seals 53 are interposed between the impeller shaft 51 and the housing portion 52 so as to prevent leakage.

2 The impeller housing 48 terminates at its rearward end in a convergent section 54 to which a pivotally supported steering Sdischarge nozzle 55 is journaled about a pair of vertically e* i i ii extending pivot pins 56. The steering nozzle 55 is steered from the steering wheel 28 in a mechanism which will be described in more detail by reference to one of the other embodiments.

The engine 13 drives an output shaft 57 that extends through a cylindrical flange portion 58 of the plate 39.

A further support plate 59 is affixed to the rear side of the bulkhead 38 by threaded fasteners 61 which also serve to affix the plate 39 to the bulkhead 38. This plate also has a cylindrical flange 62 that'is teles.coped around the flange 58.

At its rear end, the engine driven shaft 58 is connected by means of a universal joint, indicated generally by the reference numeral 63 to the impeller shaft 51, there defining an input drive shaft to the jet propulsion unit 31. A yoke member 64 has a connection to the forward end of the impeller housing portion 52 and has a pair of bifurcated arms 65 that are pivoted to a pair of rearwardly extending arms 66 of the plate 59 by means of pivot pins 67. As a result of this connection, the entire jet propulsion unit 31 may be pivoted about a transverse horizontally extending axis defined by the pivot pin 67 relative to the hull of the watercraft, for a reason which will be described. An elastic sealing boot 68 encircles .2 the universal joint 63 and provides a watertight seal in this area.

A further flexible sealing boot 69 is provided around the jet propulsion unit portion 52 and the yoke 64 so as to provide good watertight construction 30 while permitting relative rotation of the jet propulsion unit 31 about the axis of the impeller shaft 51 in a manner as will be described. The boots 68 and 69, 10 A Ui

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therefore, act together so as to provide a good watertight seal and so as to permit the movements which will be described.

'-As should be readily apparent, the jet propulsion unit 31 provides a good power source for the watercraft and nevertheless provides a very.neat and clean appearance. When the watercraft 21 is in its normal operating mode, the water inlet portion and inlet opening 46 .f the jet propulsion unit 31 will be submerged at least partially below the normal water level in which the watercraft is operating, which water level is shown in the drawings by the line 71. However, as a result of this submersion, foreign material and encrustation can occur on the .jet propulsion unit such as barnacle formation. This is not at all desireable. Therefore, an arrangement is provided for pivoting the jet propulsion unit 31 upwardly about the pivot axis described by the pivot pins 67 during periods of time when the watercraft is not in use. This mechanism includes a plate 72 that is affixed to the rear of the hull 22 beneath the tunnel 29 and rearwardly of the water inlet opening 46 of the jet 4 Spropulsion unit 31.

It should be noted that a seal arrangement 73 is carried by the. peripheral flange 47 of the jet propulsion unit housing around the inlet opehing 46 for sealing with the hull, the plate 72 and a horizontally extending flange the plate 59 when the unit is in its normal drive position, as shown' in the solid line view of Figure 3. This is important for insuring good efficiency of the jet propulsion unit 31.

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*4*4i *4444# 11 The plate 72 has a pair of upwardly extending arcuate arm~s 74 that have flanges 75 at their upper end which are secured to the .,underside of a surface 76 of the hull which defines the tunnel 29. The arms 74 have arcuately shaped slots 77 which extend along a radius defined by the pivot points defined by the pins 67 that pivotally journal the jet propulsion unit 31. A support ring 78 encircles the jet propulsion unit and specifically the impeller housing portion 48 and journals it for rotation about an axis that is coincident with the rotational axis of the impeller shaft 51. The support ring 78 has a bracket portion 79 af fixed to its upper end and which receives a pair of pins 81 for slidably supporting the support ring 78 in the slots 77 of the arms 74. In addition, a pair of hydraulic cylinders 82 are pivotally connected at one end to the pins 81 and at their opposite ends, by means of further pins 83 to a pair of lugs 84 formed on the plate 72.

When the cylinders 82 are extended or retracted, the jet *:propulsion unit 31 will be pivoted about the first axis defined ::by the pins 67 which are aligned with the universal joint 63 between its lower normal position as shown in the solid line f figure of Figure 3 to a raised or out of the water storage, sei .vice position as shown in the phantom *line views of this figure. When so raised, the unit opening 46 will be disposed '.:above the water level 71 and hence the jet propulsion unit 31 25 will be raised out of the water and the problems as aforenoted Swill not occur. In addition, all water will drain out of the jqt propulsion unit 31 and this will provide assurance against any problems.

"Xn order to provide further assurance against water damage when the watercraft is not being operated and also so as to afford access for servicing, the jet propulsion unit 31 may be rotated about the aforedescribed pivotal axis defined by the support ring 78. To this end, an electric or hydraulic motor is supported on the support ring 78 anid has a driven gear 86 that is enmeshed with a ring gear 87 formed on the jet propulsion unit 31. When the motor 85 is operated, the entire jet propulsion unit 31 will rotate about the axis of the impeller shaft 51 while the boot 69 torsionally deflects so that the unit 31 may be positioned so that the water inlet portion 45 and inlet opening 46 instead of facing downwardly face upwardly.. ,This will place the inlet opening 45 in such a direction that water cannot inadvertently enter the jet propulsion unit when it has been elevated.

This rotation also gives rise to the ability to service the door 91 for its servicing. The access door.91 has a construction unit by removing foreign particles from the impeller housing through the opening 46. To accomplish this, there is provided w' an access opening 89 in the hull portion 76 that has an access door 91 for its servicing. The access door.91 has a construction as best shown in Figure 8 and the associated openin 89 is shown for pivotally supporting a closure plate 94 for movement between .,26 a closed position as shown in Figure 3 and an open or service i position as shown in phantom in Figure 3 and also in solid lines in Figure 8. A turnbuckle type fastealer 95 cooperates with the 13 ii

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flange 92 for holding the closure plate 94 in its closed position.

'.As may be readily seen in Figure 1, an operator 96 may conveniently open the access door 91 and obtain access to the jet propulsion.unit 31 when it has been pivoted about the pivot axis defined by the pivot pins 67 through actuation of the cylinder assemblies 82.by a suitable control and when the motor has been rotated so as to swing the jet propulsion unit 31 to its service position as shown in phantom in Figure 3. The operator may easily reach into the inlet opening 46 and clear any entrapped material from the impeller housing. In addition to .permitting the jet propulsion unit 31 to be swung up for servicing as aforedescribed and for protection when not in use, the hydraulic motors 82 may be operated so as to provide trim adjustment for the unit 31.

The arms 45 in addition to providing a path of movement for the jet propulsion unit 31 as it pivots about the axis defined Sby the pivot pins 67, also serve to take side thrusts from the S jet propulsion unit during its operation. Thus, the assembly is quite rigid even though the jet propulsion unit 31 may pivot both about a horizontally extending transverse axis and a longitudinally extending horizontal axis... It should be noted that it is desirable to effect pivotal movement about the S a transverse pivot axis before rotation of the jet propulsion unit 31 about the longitudinal axis is accomplished in order to S minimize wear on the seal 73. In the illustrated embodiment, the seal 73 is being described as being carried by the flange 47 of 14 the jet propulsion unit 31. It is to be understood, of course, that the seal can be fixed to the hull of the watercraft rather than-the jet propulsion unit. In addition, various other types of seal arrangements can be employed without deviating from the invention.

In the embodiment as thus far described, the entire steering effect for'the watercraft 21 was accomplished through pivotal movement of the steering nozzle 55 of the jet propulsion unit 31.

As has been previously noted, there are times when additional steering effect may be desirable, such as when travelling at low speeds or when coasting. Figures 9 through 12 show another embodiment of the iinvention which has all of the attributes of the embodiment as thus far described and further includes a steering assist rudder mechanism, indicated generally by the reference numeral 101.

Except for this variation, this embodiment is the same as the previously described embodiment. For that reason, components which are the same have been identified by the same reference *4 numerals and will not be described again, except insofar as is 1 necessary to understand the construction and operation of this embodiment. Because of the similarities, further discussion of the jet propulsion unit, its mounting in the hull and its rotary :motion and pivotal movement will not be repeated.

Figures 10 and 12 show the steering mechanism for the steering nozzle 55. This steering mechanism includes a steering arm 102 that is integrally formed with the steering nozzle portion 55 and which has an eyelet that receives a spherical t (r joint 103 connected to one end of a bowden wire cable 104. The other end of the bowden wire cable 104 is connected to the steering wheel in an appropriate manner.

Referring now to the rudder mechanism 101, it will be seen that it has a generally inverted U shape with a pair of steering rudder arms 105 which lie on opposite sides of the steering nozzle 88 and which have a pivotal connection thereto by means of pivot pins 106 that extend outwardly from brackets 107 affixed to opposite sides of the steering nozzle 55 and which are received within openings 108 formed in the arms 105. A pair of tension springs 109 are affixed in openings 111 formed in outwardly extending'ligs 112 of the brackets 107. The opposite ends of the springs 109 are received in openings 113 formed in the rudder arms 105. The springs 109 have sufficient tensile force or preload so as to retain the rudder arms 105 in their normal submerged position where they extend beneath the plate 72 as clearly shown in Figure 9.

In the event an underwater obstacle is 'struck, the rudder arms 105 may pivot as shown in the phantom line views in Figure 10 about the pivot pins 106 so as to clear the underwater

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obstacle. Immediately upon clearing of the underwater obstacle, the springs 109 will return the rudder arms. 105 to their steering position. It should be noted that the rudder arms 105 are interconnected by a bridge portion 114 that overlies the steering nozzle 55 but which has a recess 115 therein which is sufficiently large so as to permit full tilt up of the rudder assembly 101 so as to avoid damage.

bst, 4I -16 It should also be noted that in this embodiment, the tunnel 29 is provided with a raised portion 116 at its rear end so as to clear the rudder assembly 101 when the jet propulsion unit 31 is elevated and rotated to its out of the water service or storage position.

Figures 13 through 15 show another embodiment of the invention which is generally the same as the embodiment of Figures 9 through 12 but in which a reverse thrust bucket assembly 151 is also associated with the steering nozzle 55 for generating reverse thrust and for permitting the watercraft to be operated in a reverse direction. In this embodiment, the reverse bucket assembly 151, which may take any known configuration is pivotally supported on the pins 106 and is connected to a bowden wire actuator 152 which extends to the rider's compartment 26 to an appropriate control (not shown) for steering of the watercraft. A spherical joint 153 is connected to the forward end of the bucket 151 for this operation.

Because of the incorporation of the reverse thrust bucket 151, a multipart rudder assembly, indicated generally by the *o reference numeral 154 is provided that is supported outwardly S! of the bucket assembly 151 on the pivot pins 106. The rudder assembly 154 includes a pair of spaced apart rudders 155 which .2 are, in turn, interconnected by means of a cross piece 156. In this embodiment, the torsional spring 109 is connected to the rudders 155 and to lugs 157 which, unlike the previous embodiment, are formed directly on the bucket assembly 55. Of course, a construction of the type as shown in the previously 17 <Jll described embodiment may also be employed in lieu of forming the lug 157 directly on the steering nozzle -It should be readily apparent that the reverse bucket assembly 151 may be moved between its positions without interference from the rudder assembly 154 and alzo that the rudder assembly may op'erate as in the previously described embodiment.' That is, .the rudder assembly 154 will normally be maintained in the position shown in the figures and can pivot upwardly when an underwater object is struck by the yielding of the springs 109. The springs 109 will return the rudder assembly 154 to its normal position once the underwater obj ect has been cleared.

Yet another embodiment of rudder assembly is shown in Figures 16 and 17. Since this embodiment is quite similar to those previously described, those components which are the same or substantially the same as previously described embodiments have been identified by the same reference numerals as applied 0 in those embodiments.

In this embodiment, a bracket assembly 201 is affixed to the ~~underside of the steering nozzle 55 and has a pair of bifurcated arms that receive a pin 202. A single ruCdder 203 is journaled by the pin 202 between these arms for movemept between its normal *~position as shown in the solid line view and its retracted position as shown in the phantom line View of Figure 16. A 12.5- torsional spring 204 acts between the rudder 203 and the bracket S201 and normally urges a stop 205 carried by the rudder 203 into engagement with a lug or a portion of the bracket 203. so that the rudder 203 will be held in its normal position during operation except when an underwater obstacle is struok.

,In all of the embodiments of the invention as thus far described, the jet propulsion unit 31L has been pivotal about both longitudinal and transverse horizontally extending axes. Of course, certain features of the invention may be employed by merely mounting the jet propulsion unit 31 for rotation about the longitudinally extending axis and Fig~urds 18 through 21 show such an embodiment. Because of the similarity of this embodiment'to those previously described, components which are the same or substantially the same as previously described embodiments have been identified by 'the same reference numerals and will be described again only insofar as is necessary to understand the construction and operation of this embodiment.

in this embodiment, the support plate 39 does not directly support the engine 33 but rather the engine 33 is supported solely from the underside of the hull through four mounts 37.

In addition, a flange 251 of the support'plate 39 extends 2 forwardly from the bulkhead 38 in addition to rearwardly. in this embodiment, since the jet propulsion unit 31. is not a supported for pivotal movement, the universal joint can be eliminated as can the surrounding protective boot. TAhe boot 69 is, therefore, directly interposed between the flange 62 of the :support plate 59 and the portion 52 of the jet propulsion unit 31.

The support ring 78 is, in turn, directly supported by a *fit supporting bracket 252 that is affixed to the hull portion 76 by -19 i i ii I 11 means of fasteners 253. In addition, a cover plate 254 is affixed to the rearward portion of the watercraft to enclose the tunnel 29 rearwardly of the jet propulsion unit inlet flange 47.

A seal 255 of the lip type and shown in most detail in Figures 19 through 21 is affixed to the flange 47 and sealingly engages the opening formed in the plate 254 when the jet propulsion unit 31 is in its normal driving condition as shown in the solid line views of the figures. As with the previously described embodiment, the seal may be fixed to the plate 254 rather than to the flange 47.

When the watercraft is stationary for long periods of time or: for servicing purposes, the motor 85 is operated so as to rotate the jet propulsion unit 31 about the axis defined by the impeller shaft 51 to the upper or raised position as shown in Figures 18 and 19 through a path as shown in Figure 19. In this way, the inlet opening 46 will be disposed above the water level and water can drain from the unit as aforedescribed. In i*t addition, the inlet opening 46 will be accessible for servicing through the service closure 91 as previously described.

Therefore, this construction has many of the advantages of the previously described embodiment but does not provide the pivotal movement about the transverse axis, as already noted.

In Figures 18 through 21, the engine 33 is disposed immediately adjacent the tunnel 29. It is, of course, possible to position the engine forwardly in the boat if balance in that t location is preferred.

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It should be readily apparent from the foregoing description that a number of embodiments of the invention have been illustrated and described, each of which provides a very good jet propulsion unit for a watercraft, which can be tilted up out of the water when not in use, even though thi watercraft is still submerged, so as to avoid encrustation and other deleterious effects. In addition, the jet propulsion unit may be rotated for servicing or cleaning from within the watercraft even though the jet propulsion unit is contained within a tunnel in the hull of the watercraft. As an alternative to rotating the entire jet propulsion unit, the unit may be arranged so that only the inlet portion thereof may be moved, either about the horizontally extending longitudinal axis or the transverse horizontal axis or both, with suitable sealing means being provided between the water inlet portion and the impeller stage or stages of the jet propulsion unit. Also, a variety of rudder arrangements have been depicted which will permit steering during such times when the jet propulsion unit steering effect is not great and which will nevertheless be freely moveable to a position for protection if an underwater obstacle is struck.

4 Although a number of embodiments of the invention have *2.3 been illustrated and described, various changes and 44* modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.

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Claims (14)

1. A jet propulsion unit for association with the hull of a watercraft for propelling the watercraft through a body of water comprising a housing assembly defining a generally downwardly facing water inlet portion for drawing water from the body of water in which the watercraft is operating, an impeller portion having an impeller rotatably supported for drawing water through said inXjt portion and a discharge portion for the discharge water moved by said impeller for propelling the watercraft, and means for rotating at least said water inlet portion of said jet propulsion unit about a longitudinal axis to rotate said water inlet portion from the downwardly facing position thereof.

2. A jet propulsion unit as claimed in claim 1 wherein said jet propulsion unit includes a longitudinally extending input drive shaft having its axis coincident with said longitudinal axis.

3. A jet propulsion unit as claimed in claim 1 wherein said longizudinal axis of rotation of at least said water inlet portion of said jet propulsion unit is coincident with the axis of rotation of said impeller.

4. A jet propulsion unit as claimed in any one of claims 1 to 3 further including means for supporting said jet propulsion unit for pivotal movement of at least said water inlet portion between said downwardly facing position and an elevated position.

5. A jet propulsion unit as claimed in claim 4 wherein said means for supporting said jet propulsion unit includes means for pivoting at least said water inlet portion about a pivot axis generally extending in a direction transverse to said longitudinal axis. -22

6. A jet propulsion unit as claimed in claim 4 wherein said pivot axis extends generally in a horizontal direction.

7. A jet propulsion unit as claimed in claim 5 or 6 wherein said means for supporting said jet propulsion unit for pivotal movement includes a pair of spaced apart guide rails to provide a path of movement for said jet propu. ,ion unit pivoting about said generally horizontally extending axis.

8. A jet propulsion unit as claimed in claim 7 wherein said pair of spaced apart guide rails are adapted to be fixed to the hull of said watercraft, each said guide rail having a slot receiving a pin affixed to said jet propulsion unit.

9. A jet propulsion unit as claimed in any one of claims 4 to 8 wherein said means for supporting said jet propulsion unit are adapted to support said jet propulsion unit against side thrusts thereon. 4.* 4* 44 4. a 4 4 a a rr a «a ft 0 A jet propulsion unit as claimed in any one of claims 5 to 9 further including hydraulic motor means for pivoting the jet propulsion unit about the transverse pivotal axis.

11. A jet propulsion unit as claimed in any one of the preceding claims further including further motor means for rotating at least said water inlet portion of said jet propulsion unit about said longitudinal axis.

12. A jet propulsion unit as claimed in any one of claims 2 to 11 wherein said longitudinally extending input drive shaft includes a universal joint disposed at said pivot axis. 23 I, 'Iw ci;- I

13. A jet propulsion unit as claimed in any one of the preceding claims wherein said discharge portion comprises a nozzle pivotally supported relative to said impeller portion for steering of the watercraft and further including a rudder affixed to the nozzle for generating a steering effect.

14. A jet propulsion unit as claimed in claim 13 wherein the rudder is movably supported on said nozzle for movement away from an underwater obstacle struck by the unit. A jet propulsion unit as claimed in claim 14 further including biasing spring means for urging the rudder to its normal position.

16. A jet propulsion unit substantially as herein described with reference to the description of the embodiment and drawings. Dated this TENTH day of DECEMBER 1992. 4 SYAMAHA HATSUDOKI KABUSHIKI KAISHA Applicant 4 WRAY ASSOCIATES, Perth, Western Australia, Patent Attorneys for the Applicant. 24 24 ABSTRACT A jet propulsion unit 31 has at least its water inlet portion 45 rotatable about a horizontal longitudinally extending axis so that the downwardly facing water inlet portion 45 may be rotated upwardly for access through an access opening 89 in the hull 76 for servicing. The jet propulsion unit 31 is also pivotally mounted about a first transversely extending horizontal pivot axis for bringing at least the water inlet portion 45 to an upward, out of the water position or alternat-ively bringing the jet propulsion unit 31 through trim adjusted positions to an upward, out of the water, position. In one embodiment, the jet propulsion unit 31 is only rotatable about the horizontal longitudinally extending axis. A number of embodiments of rudder assemblies 101 are also depicted supported by the steering nozzle 55 for generating steering effects when the steering nozzle 55 is not generating a significant steering effect and which may be pivoted to an out of the water position for protection when underwater obstacles are struck. li t t 4 t I I 1 4 44t4t 11c44t