Cutting system for fouling removal from jet drive water intake

A cutting system for fouling removal systems used in water-jet drive systems is described. The cutting system includes an actuation system for facilitating movement of a cutting blade that resides outside of the water flow area for the intake of the jet drive system. The cutting system also includes one or more guide tines to restrict movement of the cutting blade away from the surface of the grate. An optional cutter stud is formed as a single structure including two members forming a single angle, one member for mounting and the other for cutting. The single-angled configuration maximizes cutting efficiency while minimizing disruption of water flow to the propulsion system.

CROSS REFERENCE TO RELATED APPLICATION

The present application is related to U.S. patent application Ser. No. 11/769,972, filed Jun. 28, 2007, entitled “FOULING REMOVAL SYSTEM FOR JET DRIVE WATER INTAKE” of the same named inventor, from which application issued U.S. Pat. No. 7,377,826. The entire contents of that prior application and patent are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to systems for the removal of fouling materials such as seaweed and eel grass that can clog the intakes of jet drives. More particularly, the present invention relates to a cutting assembly arranged to resist separation from the intake grate of a jet drive. The present invention also relates to a cutting blade positioned adjacent to the impeller of the jet drive to provide improved cutting capability for the system to remove fouling from the jet drive impeller.

2. Description of the Prior Art

Watercraft have traditionally been, and primarily are, propelled through water by propellers. An alternative propulsion mechanism gaining interest is the water-jet drive. Water-jet drive systems provide a number of advantages over propeller-driven systems. They eliminate a number of support and attachment components, such as rudders, propeller shafts, propellers, that increase vessel drag and limit shallow water passage. Moreover, they are safer for people and marine life in proximity to the stern of the vessel in that the moving parts are located within the hull envelope. They also tend to be quieter than propeller systems and maneuverability is enhanced at all speeds. Water-jet drives also tend to provide increased fuel economy. For these and other reasons, the water-jet drive has become increasingly popular as a watercraft propulsion system.

Water-jet drive systems propel watercraft by rapidly accelerating a relatively small volume of water over a distance. This is accomplished using one or more impeller stages located within the watercraft hull. The impeller includes a plurality of blades confined in a housing. Rotation of the impeller blades draws water into an intake of the housing, past the blades, and through an outlet at the stem. The housing is ordinarily designed to direct flow such that the water is expelled above the waterline of the watercraft. The housing may be tapered toward the outlet to increase water acceleration and maximize thrust. Improved propulsion efficiency occurs when there is a close fit between the ends of the impeller blades and the interior of the housing.

An important aspect in the effective operation of the water-jet drive is the availability of an adequate supply of water to be expelled from the housing outlet. For that reason, in general, a larger intake is desirable as it ensures a greater water supply available to the impeller to generate thrust. On the other hand, a large intake allows the impeller to draw debris in with the water. It is desirable to minimize debris contact with the impeller, which debris may damage or destroy the blades or clog the impeller. It is therefore useful to avoid or minimize drawing into the housing debris of any size or type that will cause damage or fouling of the impeller while keeping the intake as open as possible.

Manufacturers of watercraft using water-jet drives place intake grates at the housing intake to catch relatively large-sized debris and prevent such debris from reaching the impeller. In relatively clear water, these grates serve their purpose adequately. However, when the watercraft passes through patches of heavy debris—seaweed and eel grass in particular—the grate is overwhelmed and the intake is substantially blocked. In other instances, this type of debris or fouling passes through the grate and then sticks to the front leading edges of the blades of the impeller within the housing. Either type of fouling results in a substantial reduction of thrust capability and corresponding slowing or halt to movement of the watercraft. Unexpected substantial slowing or halting of the watercraft can be a serious safety issue for the watercraft operator and occupants, dependent upon sea conditions, weather and location.

Water-jet drive watercraft operators resolve such fouling problems in several ad hoc ways. First, they may reverse the direction of rotation of the impeller to force the fouling to move away from the intake in the hope that it will be dislodged from the grate. Second, they attempt to access the housing through an observation port below the deck and try to pull out any fouling contained therein. Third, they may be forced to jump into the water, swim under the watercraft, and pull the fouling away from the grate by hand. These options are either ineffective or an undesirable way to solve the problem. Examples of described devices can be found in U.S. Pat. Nos. 6,482,055; 6,183,319; and 6,083,063. However, these devices and the ad hoc techniques described above fail to address adequately the problem of fouling removal in water-jet drives. Worse, these ad hoc methods and described devices require that the watercraft be completely stopped before they can be performed or used. Therefore, not only are they ineffective at removing debris, they interrupt an otherwise enjoyable sail. When they must be performed or used repeatedly, which is often the case, given their ineffectiveness, the sailing experience can be ruined entirely. In order to reverse the impeller to “backflush” the water-jet drive housing in the hope of dislodging the debris on the grate, it is necessary to have a transmission coupled to the impeller to effect that reversal. The transmission is a costly and heavy component that must also be maintained. It would be preferable to avoid addition of a transmission for the purpose of changing impeller rotation.

U.S. Pat. No. 7,377,826 describes a system capable of removing fouling materials from the intake of a water-jet drive. That system provides a fouling removal system that may be incorporated into existing water-jet drive structures or incorporated into new construction. Further, that fouling removal system may be operated automatically using a control device in proximity to other control devices of the watercraft. Still further, that fouling removal system does not require the inclusion of a transmission to enable impeller rotation changes. Yet further, that fouling removal system includes a secondary mechanism for removing debris fouling the impeller blades of a water-jet drive. Even further, that fouling system is capable of removing debris from the intake grate and impeller of a water-jet drive while a watercraft is stationary or is operating at any speed, including full speed.

However, the fouling removal system described in U.S. Pat. No. 7,377,826 has certain features that limit the optimization of its performance characteristics. First, the mechanism for cutting the debris from the grate of the propulsion system may not be able to cut through large bunches of seaweed as the bulk of the blockage forces the blade to ride over the seaweed. Also, high water flow rates through the grate may cause the blade to lift as it is actuated. In both instances, in sufficient quantities of seaweed or eel grass are sheared. In particular, the degree and frequency of blade lifting away from the grate may increase with increased seaweed bulk and/or when the boat is traveling at high speeds. Second, the actuation mechanism of the existing system is positioned at least partially in the flow path of water passing through the grate. That positioning can be a point of debris retention that cannot be resolved with the cutter. It also creates turbulence, which can create noise as well as lessen the efficiency of the water-jet drive. Third, the passive cutter stud of the system described in U.S. Pat. No. 7,377,826 has shown effective removal of debris located on or near the impeller, but there remains some seaweed clogging near the shaft of the impeller. It would be preferable to be remove all, or substantially all, such debris from the impeller including near the impeller shaft. Fourth, it can be difficult to place the passive cutter stud sufficiently close to the impeller to enable effective debris removal at that location.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide enhanced performance to a system capable of removing fouling materials from the intake of a water-jet drive and impeller. It is also an object of the invention to eliminate the separation of the blade from the grate during the cutting process to improve performance. Still further, it is an object of the present invention to provide enhanced cutting capability to a fouling removal system. Yet further, it is an object of the present invention to provide a fouling removal system with improved performance and cutting capability under all conditions of operation of a vessel with a water-jet drive.

These and other objects are achieved with the present invention, which is a cutting system for cutting away seaweed, eel grass, and other similar types of stringy or otherwise clinging debris from the intake of a waterjet drive. The cutting system includes a cutting blade and a set of guide tines configured to restrict vertical movement of the cutting blade as it passes along the surface of the intake grate of a water-jet drive. In particular, the one or more guide tines form a confined area between the tines of the intake grate and those guide tines. Each guide tine forms a slot through which the cutting blade passes. The upper portion of the guide tine is spaced from its lower portion, or from a grate tine, enough to allow the cutting blade to pass there between while also preventing the cutting blade from lifting away from the grate tines during the cutting process. The cutting system also includes an actuator system for moving the cutting blade that is located adjacent to, but outside of, the cutting area and outside of the flow path for water entering the propulsion system.

The cutting system includes an optional passive cutter stud located within the housing adjacent to the impeller. The cutter stud includes a sharpened surface at least at its leading edge. The cutter stud is affixed to the interior of the housing near the impeller blade such that any debris buildup on the leading edge of the impeller blades contacts the sharpened surface and is cut into pieces to pass through the impeller. The cutter has a cutting edge that is shaped and located to minimize its distance from the leading edge of the impeller. The minimal clearance provided by this arrangement provides optimum cutting capability. The shape of this improved cutter stud decreases resistance to water flow and increases cutting ability.

The cutting system of the present invention enables the removal of fouling materials from the intake grate of a water-jet drive. The present invention may be incorporated into the control functions of the watercraft. The actuation system of the invention may be incorporated into hydraulic supply arrangements existing in the watercraft.

The cutting system enhances the ability of a fouling removal system to permit a watercraft operator to remove fouling at the intake grate without manual removal action. It cuts away the debris to ensure that the debris will not remain on the grate. These enhancements are especially valuable when the volume of water passing through the grates is higher, such as when the vessel is traveling at high rates of speed. Additionally, the present invention enhances the ability of fouling removal systems to substantially and efficiently keep the water-jet drive housing clear of debris so that the watercraft remains fully operational and is not suddenly and unexpectedly incapacitated when passing through seaweed. That enhances watercraft safety.

These and other advantages of the present invention will become apparent upon review of the following detailed description, the accompanying drawings and the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is a cutting system110for removing fouling such as seaweed, eel grass, or the like, from the intake grate of a water-jet drive system of a watercraft while the watercraft is stationary or is operating at any speed, including full speed. With reference toFIG. 1, the cutting system110is shown in position with respect to a watercraft112. The cutting system110includes a cutter arm system114and, optionally, a cutter stud116. The cutting system110is designed to cut away debris clogging an intake grate118and/or an impeller120within a housing174of the water-jet drive system122. The water-jet drive system122is coupled to an engine123. The cutter arm system114is coupled to a hydraulic pump125and is may be automatically actuated using a control switch127. In one embodiment of the invention, the cutting system110includes the intake grate118having a frame124. In this arrangement, the cutting system110includes a grate assembly to be described with reference toFIGS. 2 and 3. In an alternative embodiment, the cutting system110does not include a grate assembly, but instead may be affixed to an existing grate118.

As illustrated inFIGS. 2 and 3, the cutter arm system114includes a blade126, an actuation system128, a first pivot assembly130, a second pivot assembly131, and a blade housing132. The blade126includes a first surface126aand a second surface126b. One or both of the blade surfaces may be sharp. The blade126is shown at a first position A retracted within the blade housing132and in a second position B extended out of the blade housing132. The cutter arm system114includes a forward end134and a rear end136. The forward end134is removably affixed to a forward mounting plate138of the frame124using first bolt140. The rear end136is removably affixed to the first end of a pivot plate141using first pivot bolt142. The second end of the pivot plate141is removably affixed to the rear mounting plate143of the frame124using second pivot bolt144. The blade housing132is affixed to the forward mounting plate138using the first bolt140and to the rear mounting plate143using the second pivot bolt144. The cutter arm assembly114is preferably mounted exterior to the intake grate118, wherein the frame124and tines (described herein) of the intake grate118are positioned within the opening of, and affixed to, the mounting block of the watercraft112substantially flush with the mounting block while the cutter arm assembly114extends outwardly from the plane of the opening of the mounting block. It is to be understood that other means for joining the cutter arm assembly114to the watercraft112at the intake of the water jet drive system may be employed without deviating from the basic functionality of the cutter arm assembly114. For example, the cutter assembly114may be connected at the interior of the watercraft112by joining it to the interior side of the mounting block with the second pivot bolt144extending through the mounting block and rotatably joined to the blade126such that the frame and tines set within the mounting block opening and the cutter arm assembly114is substantially flush with the mounting block. The present invention, along with other structures, such as the watercraft shaft, for example, may then be essentially contained within the watercraft112and provide improved hydrodynamics. It is to be noted that the cutter arm assembly114may be connected to the housing174of the water jet drive system122instead of being connected directly to the watercraft112, wherein the water jet drive system122is connected to the mounting block of the watercraft112.

The actuation system128includes a hydraulic cylinder146removably connected to the forward mounting plate138and the blade126, and hydraulic fluid transport means, such as flexible piping148, coupled to the hydraulic pump125. The hydraulic cylinder146includes a first end150and a second end152. The first end150is engaged with the first bolt140and is therefore fixedly connected to the forward mounting plate138. The second end152is affixed to pivot plate141with the first pivot bolt142. The pivot plate141is affixed to the blade126at the first surface126awith the second pivot bolt144. The hydraulic cylinder146is arranged to be positioned between the blade126and the blade housing132when the blade126is in retracted position A. The hydraulic cylinder146is sized and arranged to provide sufficient force to cause movement of the blade126when actuated by operation of the hydraulic pump125. It is to be understood that other means may be used for joining the hydraulic cylinder146to the forward mounting plate138and the blade126.

With continuing reference toFIGS. 2 and 3, the second pivot assembly131includes a housing bushing156in rotatable engagement with the second pivot bolt144and a mounting bushing158affixed to the rear mounting plate142and to the housing bushing156. The housing bushing156includes a first end160rotatably coupled to an interior surface of the blade housing132and a second end162removably coupled to the first surface126aof the blade126. The housing bushing156may have male threading at the first end160and the second end162as the means for engagement with the blade housing132and the blade126, but is not limited thereto. The housing bushing156is preferably fixedly engaged with the blade126such that they rotate in unison when the blade126is moved by operation of the hydraulic cylinder146.

As an improvement over the cutting system described in U.S. Pat. No. 7,377,826, the cutting system110of the present invention includes one or more guide tines165. The guide tines165are configured as slotted structures. Each includes an upper structure165aand a lower structure165b. The structures165aand165bare spaced from one another by a gap165c, which is sized and shaped to permit the blade126to pass therethrough. That is, under structure165aand over structure165b. In this way, the blade126is prevented from lifting away from structure165band from any of grate tines164, which are not slotted and which are affixed to the grate frame124. In an alternative embodiment, the guide tines165are not slotted. Instead, each is positioned above one of the grate tines164in a configuration that creates a gap there between so as to produce the slotted arrangement through which the blade126may pass when actuated.

When the watercraft112is functioning as expected and there are no apparent indications of reduced efficiency of the water-jet drive system122, the actuation system128is dormant and the blade126is retracted within the housing132out of the cross sectional area of water flow through the intake grate118. When the watercraft operator detects a reduction in efficiency of thrust, the actuation system128may be activated through switch127to cause the extension of the hydraulic cylinder146such that the second end152moves along a path identified as path C. The movement of the hydraulic cylinder146along path C causes the pivot plate141to rotate, which in turn causes the blade126affixed thereto to swing out of the blade housing132in an arc from position A to position B. The first and second pivot assemblies130,131, cause the movement of the blade126by each pivoting in opposite directions, which keeps the hydraulic cylinder146outside of the portion of the intake grate118through which water flows during operation, allowing water to flow to the propulsion system with minimum interference.

The blade126at second surface126bpasses in close proximity above or flush against tines164of the intake grate118and through guide tines165. The second surface126bmay be sufficiently sharpened to ensure that all debris located on the tines164is severed and allowed to pass either into the housing174of the water-jet drive system122(shown inFIG. 1) or below, and therefore completely removed from, the watercraft112. As noted, either or both surfaces of the blade126may be sharpened enough to enable the cutting of debris upon actuation. In addition, a shear plate of the intake grate118may be similarly sharpened so that as blade126approaches it upon actuation, the blade126and the shear plate produce a scissoring effect to shear off debris located on the intake grate118. It is to be noted that one or more portions or all parts of the cutting components of the cutting system110may be carbide or other type of material, such as nonmetallic materials including, but not limited to, composite materials. Other components of the cutting system may also be made of such materials, provided such materials are selected to perform the indicated functions under the conditions expected for the watercraft112. The movement of the blade126may be reversed such that it swings back across the intake grate118between the gap165cformed by the guide tines165, or by the grate tines164of the intake grate118and the guide tines165, until the blade126enters the blade housing132by continued activation of the actuation system128. The process may be repeated as desired until a return to expected water-jet drive system122efficiency is observed.

As shown inFIGS. 2 and 3, the fouling removal system110includes intake grate118having relatively narrow grate tines164as compared to those grate tines existing on conventional water-jet drive grates known to those of skill in the art. The narrow tines164are arranged to ensure maximum available water flow through to the water-jet drive impeller or impellers while maintaining a mechanism for capturing fouling debris such as seaweed and eel grass. The guide165tines are similarly shaped in width.

The intake grate118is preferably a unitary device including a flange166from which the grate tines164and the guide tines165extend across intake opening168. The flange166forms an integral part of and connection to the rear mounting plate142. Each of the grate tines164and the guide tines165may also include a tapered end170at forward end134in conjunction with forward mounting plate138. Alternatively, the cutting system110may be affixed to an intake grate supplied by the original equipment manufacturer. In that case, the forward mounting plate138and the rear mounting plate142would be affixed to the perimeter of the existing intake grate and the blade position in relation to the tines164and165adjusted as necessary.

The cutting system110of the present invention may further include the optional cutter stud116, which is shown in a specific example inFIGS. 4-7. The cutter stud116has two members, a first member191and a second member192. The first member191and the second member192are connected to, or are integral with, each other and form a single angled conduit184. The cutter stud116is removably affixable at second member192to interior surface172of the housing174of the water-jet drive system122in close proximity to the impeller120at the upstream side thereof. For example, second member192of the stud116may be removably affixed to the interior surface172by using one or more fastening studs188. The single angled design of the stud116allows maximum flow of water through the stud116to the impeller120. The cutter stud116may be used in combination with the cutter arm system114or it may be a stand-alone device. It is arranged to remove debris stuck or attached to the impeller120and carried around as the impeller120rotates. The cutter stud116is therefore suitable for maintaining maximum efficiency of the impeller120itself. This also generally translates into enhancing the overall fuel efficiency of the water-jet drive system122and, as a result, the watercraft112.

The cutter stud116includes a sharpened cutting edge176on end191aof the first member191by which blades178of the impeller120pass as they rotate. The length of the sharpened cutting edge176on end191acan be sized to minimize the distance between it and the hub of the impeller20. The cutting edge176may include carbide. The first member191is preferably sized and shaped on end191ato match the profile of the impeller120and is sloped at its forward location to minimize water flow disruption. Further, the narrow profile of the cutter stud116by the single-angled arrangement of the members191and192also minimizes water flow disruption. Overall, this arrangement ensures that any debris stuck to the blades178, between blade tips180and/or the interior surface172of the housing174, contacts the cutting edge176and is severed such that it will pass through the impeller120in relatively small pieces. The cutter stud116is preferably of a length sufficient to extend near to the impeller shaft182, but is not limited to that length and may therefore be shorter.

It is to be understood that the cutter stud116may be attached in other ways or may be permanently attached to the housing174. For example but in no way limited thereto, the fastening stud188may be formed integrally with one of the members of the stud116, such as second member192, and thereby either minimally intrude into the single-angled conduit184, or not extend at all into that space. It is also to be understood that the stud116is not limited to the design of the specific example, and therefore the stud116may be alternatively arranged in any reasonably equivalent form thereof with the goal of minimizing adverse impact on water flow through the housing174. For example but in no way limited thereto, the stud116may be fabricated as a single integral piece. That is, the first member191, the second member192and the fastening studs188are formed as a single structure. Optionally, two or more of those components may be separate structures joined together in some manner.

In an alternative embodiment of the invention related to the cutter stud116, the housing174may be modified to include oversized holes with dimensions that exceed the outside dimensions of the fastening studs188. Because minimizing the spacing between the cutter stud116and the impeller120is advantageous, the oversized holes may be used to aid in the installation of the cutter stud116as close as desired to the impeller120as possible, rather than going through the process of approximating positions for the entry holes in the housing174for the fastening studs188by trial and error. Once the desired position for the fastening studs188is established by moving them within the oversized holes of the housing174, the fastening studs188may be secured so that the cutter stud116is in a desired position with respect to the impeller120. The fastening studs188may further be secured in position by filling the oversized holes with a filler, such as epoxy, for example. Optionally, a bushing or tube may be used within each of the oversized holes as a sleeve for the fastening stud188. Once the desired position of the cutter stud116has been established adjacent to the impeller120, the fastening studs188contained in the bushings may be tightened. The filler may then be used to secure the bushing in the slot201. This arrangement allows for easy removal and replacement of the fastening studs188, knowing that the positioning of the bushing, which is fixed in the filler in the oversized hole, is correct for the next set of replacement fastening studs188.

The components of the cutting system110may be selected based upon the environment within which they will perform, ease of manufacture, durability, compatibility with other components of the watercraft112and pricing. For example, one or more of the components may be made of nonmetallic materials. In addition, one or more components may be fabricated of metallic materials. In the preferred embodiment of the present invention, the components of the cutting system110are made of a corrosion-resistant material, such as stainless steel, and cutting surfaces may include carbide. The hydraulic cylinder146may be of the type generally commercially available and known to those skilled in the art. The hydraulic cylinder146may be joined to manually operable or automatically operable hydraulic pumps or other hydraulic fluid supply means in a manner well understood by those skilled in the art.

The improved cutting system for fouling removal systems of the present invention including the cutter arm system114and the optional improved cutter stud116enable the operator of a watercraft having a water-jet drive system122to remove fouling debris from the intake grate118, the impeller120, or both when a reduction in operating efficiency is observed. The operator may conduct such removal quickly and conveniently without going through the ad hoc manual steps previously described. No impeller transmission is required to effect debris removal. The operation of the watercraft is generally safer as sudden unexpected slowing or halting of the watercraft as a result of debris clogging of the intake is quickly and easily eliminated.

The present invention has been described with respect to various combinations of preferred components. Nevertheless, it is to be understood that various modifications may be made without departing from the spirit and scope of the invention as described by the following claims.