Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H25/00—Steering; Slowing-down otherwise than by use of propulsive elements; Dynamic anchoring, i.e. positioning vessels by means of main or auxiliary propulsive elements
  • B63H25/02—Initiating means for steering, for slowing down, otherwise than by use of propulsive elements, or for dynamic anchoring
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H11/00—Marine propulsion by water jets
  • B63H11/02—Marine propulsion by water jets the propulsive medium being ambient water
  • B63H11/04—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps
  • B63H11/08—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps of rotary type
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H11/00—Marine propulsion by water jets
  • B63H11/02—Marine propulsion by water jets the propulsive medium being ambient water
  • B63H11/10—Marine propulsion by water jets the propulsive medium being ambient water having means for deflecting jet or influencing cross-section thereof
  • B63H11/103—Marine propulsion by water jets the propulsive medium being ambient water having means for deflecting jet or influencing cross-section thereof having means to increase efficiency of propulsive fluid, e.g. discharge pipe provided with means to improve the fluid flow
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H25/00—Steering; Slowing-down otherwise than by use of propulsive elements; Dynamic anchoring, i.e. positioning vessels by means of main or auxiliary propulsive elements
  • B63H25/02—Initiating means for steering, for slowing down, otherwise than by use of propulsive elements, or for dynamic anchoring
  • B63H25/04—Initiating means for steering, for slowing down, otherwise than by use of propulsive elements, or for dynamic anchoring automatic, e.g. reacting to compass
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H11/00—Marine propulsion by water jets
  • B63H11/02—Marine propulsion by water jets the propulsive medium being ambient water
  • B63H11/04—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps
  • B63H2011/043—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps with means for adjusting or varying pump inlets, e.g. means for varying inlet cross section area
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H11/00—Marine propulsion by water jets
  • B63H11/02—Marine propulsion by water jets the propulsive medium being ambient water
  • B63H11/04—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps
  • B63H2011/046—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps comprising means for varying pump characteristics, e.g. rotary pumps with variable pitch impellers, or adjustable stators
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H11/00—Marine propulsion by water jets
  • B63H11/02—Marine propulsion by water jets the propulsive medium being ambient water
  • B63H11/04—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps
  • B63H11/08—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps of rotary type
  • B63H2011/081—Marine propulsion by water jets the propulsive medium being ambient water by means of pumps of rotary type with axial flow, i.e. the axis of rotation being parallel to the flow direction

Definitions

• This invention relates to Marine Jet Propulsion Systems, and more particularly to such systems of an improved design, which are more efficient over a range of vessel speeds and loads.
• a marine jet propulsion system includes an inlet duct, a pumping means and a nozzle.
• the inlet duct delivers water from under the hull to the pumping means, which is driven by an engine.
• the pumping means delivers the water through the nozzle, which produces a water jet, thereby propelling the watercraft through the body of water in which the watercraft moves.
• a reversing bucket redirects the jet flow back under the boat fully for reverse thrust and partially for neutral thrust.
• the water jet When the watercraft is operating in a planing mode, the water jet obliquely strikes the water surface behind the watercraft, which results in turbulence on the water surface. Such turbulence is dependent on the velocity of the water jet relative to the water surface.
• the water jet interacts with the water surface to produce a high turbulent spray of water behind the boat, which is commonly called a "rooster tail.”
• the rooster tail is commonly considered objectionable for water skiing and wakeboarding behind the watercraft.
• Reducing the velocity of the water jet relative to the water surface eliminates the rooster tail, but still leaves a turbulent trail of surface water in the wake of the watercraft, which is still objectionable to wake boarders, who like to use short ropes.
• a further reduction of the velocity of the water jet relative to the water surface would be desirable for the further reduction of the turbulent trail of surface water in the wake of the watercraft.
• Trash management is another shortcoming of the marine propulsion systems of the prior art.
• Many types of floating debris can become lodged on the grate that covers the inlet of the system, which restricts the flow of water into the pump and reduces propulsion efficiency.
• the fibrous material is also well known to lodge on the leading edges of pump and stator vanes, reducing pump efficiency.
• the rope is particularly difficult to disentangle, when it becomes wrapped around the impeller and the drive shaft.
• Some jet boats carry hand rakes with right angle bends in the handle to remove debris from the inlet grate, and some integrate moveable grate sections to remove such debris, but these methods are awkward and only partially effective.
• Some commercial water jet propulsion systems are equipped with a reversing transmission, which is used to back flush both the pump vanes and the grate.
• commercial systems and river boats are commonly equipped with a clean-out hatch, which can be removed to allow the operator to remove debris from the pump inlet by hand. It would be desirable to reduce or eliminate the need for the trash handling mechanisms and methods by providing trash handling and back flushing methods integral to the design of the marine j et propulsion system.
• an object of the invention to provide an improved marine jet propulsion system, which combines 75 a variable pitch pump impeller and a variable nozzle under microcontroller controls to create a continuously variable power transmission, so that the engine is always operating close to its most efficient rpm.
• variable pitch impeller pump It is a further object of the invention to maintain the variable pitch impeller pump close to its most efficient operating conditions over both a wide range of shaft rpm and a wide range of watercraft speeds, while simultaneously achieving the objects and advantages stated above.
• the scissoring action will also be seen to be effective in cutting rope and fishing line that may be sucked
• variable pitch vanes to produce a reverse pumping action through the system, which becomes an effective reverse thrust when controlled in concert 110 with the variable inlet and the variable nozzle, thereby eliminating the need for the reversing bucket. It is a further object of the invention to utilize the same nozzle vanes for reverse steering as are used for forward steering and nozzle flow regulation.
• an improved marine jet propulsion system which combines a novel variable pitch spherical pump impeller and a variable steering nozzle to create a continuously variable power transmission, so that the engine is always operating close to its most efficient rpm. Reducing the pitch on the variable pitch spherical pump to near zero provides a neutral power transmission. Further reducing the pitch results
• 125 boats of the prior art can be used to reduce vortex formation and cavitation in the reverse thrust mode.
• variable pitch spherical pump incorporates concentric spherical surfaces on the impeller hub and on the pump housing.
• the axes of rotation of the variable pitch impeller vanes are radii of the concentric spherical surfaces, and the inner and outer edges of the variable pitch impeller vanes are also spherical surfaces, which fit closely to the
• This geometry allows the variable pitch impeller vanes to rotate about the axes of rotation, while constantly maintaining close fits between the inner and outer edges of the vanes and the impeller hub and the pump housing, respectively.
• the close fits are well known in the pump design field of art to contribute to efficient pump operation.
• this geometry allows the vanes to rotate to near zero pitch required for effectively neutral power transmission, while providing close fits
• variable nozzle In the forward thrust mode of operation, the variable nozzle is controlled to maintain the most efficient head on the 140 variable pitch impeller pump for the current shaft rpm, as is described in my US Patent 5,679,035. It is well understood in the art that the most efficient head on the variable pitch impeller pump is largely dependent on the square of the shaft rpm. It is also well understood in the art that the most efficient head on the variable pitch impeller pump is only very slightly dependent on impeller pitch. Hence, the pump will always be operating close to peak efficiency, when the variable nozzle is controlled to maintain pump head as a function of square of the shaft 145 rpm.
• a microcontroller incorporates inputs from differential pressure transducers to determine the head on the pump and 160 the flow through the system.
• the microcontroller gets an rpm input from an engine tachometer.
• the control program in the microcontroller incorporates a look-up table of the pump efficiency as a function of shaft rpm. From these inputs the control program determines the shaft power demand of the pump.
• the control program also incorporates a look-up table, which allows interpolation of the most efficient power supplied at each shaft speed by the engine, as is well understood in the art of industrial controller programming.
• the control program compares the 165 calculated pump power demand to the power most efficiently supplied by the engine at the input rpm, and adjusts the pitch on the variable pitch impeller to adjust pump shaft power demand to approximate the most efficient power supply of the motor at the input rpm. Simultaneously, the variable steering nozzle is adjusted to maintain the pump at its most efficient operating head for the shaft rpm.
• the pitch on the variable pitch impeller is controlled by reference only to the throttle position on the engine.
• the efficient power supplied by the motor is largely dependent on the throttle position, and the pump power demand is largely dependent on impeller pitch, so linking the impeller pitch to the throttle position approximately maintains efficient engine operation.
• the variable steering nozzle is adjusted to maintain the pump at its most efficient operating head for the shaft rpm.
• the pitch on the variable pitch impeller is adjusted based on an engine loading output from a combustion microcontroller on the engine.
• combustion microcontrollers commonly use a variety of sensors on the engine to control fuel injection, ignition timing and electric servo valve timing.
• Such combustion microcontrollers also commonly output engine-loading signals to
• the operator can also reverse the pitch to clean the vanes and to back flush the system.
• the operator increases the flow through the jet in a controllable way, either in forward or reverse, eliminating any starting jerks or uncontrollable movement of the watercraft.
• the same steering wheel or other steering control method is effective in steering the boat in either forward or reverse.
• the microcontroller sets the pump impeller pitch near maximum.
• the microcontroller opens the variable 200 steering nozzle to maximum. In addition to maintaining engine efficiency, this control strategy has the fortunate consequence of providing maximum flow at low speeds for maximum propulsion efficiency. The flow through the maximum nozzle opening also occurs at the lowest possible velocity. Thus, motor efficiency, pump efficiency, and flow rate efficiency are all close to optimum, and wake turbulence is minimized.
• control system When the system is under full acceleration, as in pulling up a water skier, the control system will reduce the pump impeller pitch to match the pump's shaft power demand to the engine's most efficient power supply at the instantaneous shaft rpm. The control system will also reduce the nozzle area to maintain the most efficient head on the pump for its current rpm.
• variable inlet duct opening is near maximum due to the high flow, which results in no losses from the conversion of inlet entrance velocity to pressure at the pump inlet. This again has the fortunate consequence of providing close to
• the control system reduces impeller pitch to allow the engine higher rpm. Reduced impeller pitch requires a commensurate reduction in nozzle area. Pump head is rising as the square of the rpm. Inlet head is rising as the square of the boat speed. The increasing pump rpm, the reducing pitch, and the higher inlet pressure are all factors, which will result in the control system's reducing the nozzle area to maintain peak pump efficiency. Hence, nozzle area is reduced with increasing rapidity as boat speed increases as a natural consequence of the system operation,
• the minimum nozzle area at top speed is also ideal for reducing the system flow rate, hence improving propulsion efficiency at the higher speed.
• FIG. 1 is a plan view of the bottom of a boat, which incorporates an Improved Marine Jet 245 Propulsion System, showing the hull, inlet duct, pump housing, variable nozzle, and the swim platform.
• FIG. 2 is a midline vertical section view indicated on FIG. 1, showing the internal details of the improved marine jet propulsion system and the control system schematic.
• FIG. 3 is an enlarged view of the area indicated on FIG. 2, which shows the details of the hydraulic control piston for the vane pitch.
• FIG. 4 is an enlarged view of the area indicated on FIG. 2, which shows the details of the impeller hub and vane pitch operating mechanism.
• FIG. 5 is a section view indicated on FIG. 2 Showing the vanes in the inlet duct and the sliding gate beneath the vanes.
• FIG. 6 is the section view indicated on FIG. 2 showing the variable vane operating mechanism of 255 the pump.
• FIG. 7 is a rear section view of the boat indicated on FIG. 2 showing the variable rectangular nozzle under the swim platform.
• FIG. 8 is an schematic overhead view of the variable steering nozzle showing the various vane positions that result from the actions of the hydraulic nozzle controls.
• FIG. 9 is a schematic representation of the nozzle hydraulic system, which shows the integration of the steering function, the nozzle area reduction function, and the nozzle pitch function.
• FIG. 10 is a section view indicated on FIG. 1 showing the power trim adjustment of the propulsion system and the maximum declination, which is used in reverse mode.
• FIG. 11 is a graph on which shaft power is plotted against shaft rpm, showing the relationships
• FIG. 12 is a flow chart for the microcontroller program used to control the variable pump vane pitch, the variable nozzle area and the variable inlet entrance area in all embodiments of the invention.
• FIG. 13 is a flow chart for three alternative microcontroller programs used to control the variable impeller vane angle for efficient engine operation in the forward mode of operation.
• FIGS. 1-13 there is shown an improved marine jet propulsion system, generally referred to as 20, designed to achieve higher propulsion efficiency, greater maneuverability, and better injury prevention features than currently available marine propulsion systems.
• the system 20 includes a variable water inlet duct 30 for admitting water into the system 20, a variable-pitch spherical pump 50 capable of receiving and pumping a relatively large amount of incoming water, and an adjustable, large variable rectangular discharge nozzle 80 capable of forcibly exiting the water pumped by the pump 40 to propel the watercraft 19 through the body of water 29.
• a microcontroller 120 controls the variable inlet duct 30, the variable pitch spherical pump 40 and the variable discharge nozzle 80.
• the inlet duct 30 is designed so that hydraulic efficiency of the system 20 is optimally maintained at all watercraft 19 velocities, as described in my US Patents.
• the entrance area of the entrance opening 32 is varied by the action of the hydraulic cylinder 34 on the adjustable slide 31 to match the velocity of the water in the entrance opening 32 to the velocity of the water passing under the watercraft 19.
• the inlet duct 30 includes an adjustable slide 31 located over the entrance opening 32 of the hydraulically efficient, elongated inlet tunnel 33 formed or attached to the bottom of the watercraft 19.
• the hydraulic cylinder 34 moves the adjustable slide 31 to vary the effective area of the entrance opening 32.
• the inlet tunnel 33 is longitudinally aligned on the watercraft 19 with a front entrance opening 32 and a rear exit opening 49. 295
• the inlet tunnel 33 gently curves upward inside the watercraft 19 and has a larger cross-sectional area at its exit opening 49 than at its entrance opening 32, when the adjustable slide 31 is in its forward position as shown in FIG. 2.
• the surrounding surface of the entrance opening 32 of the inlet tunnel 33 is gently curved from tangent to bottom of the watercraft 19 so that turbulence is minimal at the entrance opening 32 of the inlet duct 30.
• the grate structure 40 fits in the elongated inlet tunnel 33 and attaches to the watercraft 19 with fasteners 48, so that the conversion of excess entrance velocity at the entrance opening 32 into pressure at the rear exit opening 49 takes place largely in the rectangular passages 41 between the grate vanes 42. It is well understood in the art of hydraulic design that dividing the flow into such rectangular flow channels 41 reduces turbulence losses the water flow 44, which are larger than the factional losses against the vane surfaces.
• the control system 100 moves the adjustable
• the grate structure 32 includes a plurality of spaced apart, longitudinally aligned elongated grate vanes 42.
• the middle grate vane 43 is vertically truncated to allow passage for the shaft 36 of the hydraulic cylinder 34, which passes through the watercraft 19.
• the shaft 36 is attached to the adjustable slide 31
• the adjustable slide 31 is held in place by the slide rails 46, which are attached to the grate structure 40 with the fasteners 47.
• the leading edge 37 of the adjustable slide 31 bends downward so that the effective entrance angle of the leading edge 37 is approximately parallel to the upper inlet surface 39 of the inlet tunnel 33, so that the velocity of entrance flow 45, which is parallel to the upper surface 39 will approximately
• the slide 31 is in the forward position shown in FIG. 2.
• the controller 120 progressively moves the slide 31 forward. It can be seen that this has two effects --first, it reduces the effective area of the entrance opening 32 of the inlet tunnel
• the pump 50 Disposed adjacent to the exit opening 49 of the inlet tunnel 33 is the pump 50, which is coupled via a drive shaft 51 and gear reduction 100 to an engine 21.
• the pump 50 is contained in a split spherical pump housing 62, which is attached to the grate structure 40 with the fasteners 64.
• the pump 50 is axially aligned
• the pump 50 includes a spherical impeller 52, which rotates to forcibly deliver the incoming water from the exit opening 49 to the discharge nozzle 80 located on the opposite side of the pump 50.
• the pump 50 is designed to be used with a 300 horsepower engine so that the mass flow equals approximately 2200 lbs/sec and the pump head is approximately 70 feet at full power with 18-
• the pump 50 uses a 16-inch spherical impeller 46, which matches the size of the diffuser 70, which is disposed over the aft position of the pump 50 to recover the vortex velocity produced by the pump 50 as useful propulsive momentum, as is common in the art of pump design.
• the stator vanes 71 of the diffuser 70 support the diffuser hub 72, which contains the tapered roller bearings 73 and 74.
• the bearings 73 and 74 are first mounted on the pump shaft 75, which is inserted into the diffuser hub 72.
• the bearing collar 75 is bolted to the hub 72 to carry the thrust of the bearing 73 and to provide mounting surfaces for the mechanical seal 77.
• the spherical impeller hub 53 is bolted to the pump shaft 75.
• the return spring 54 and the spider 55, engaging the operating arms 56, are held in place by a press, while the vanes are inserted radially through the bearing holes 58 and the operating arms 56. Each vane is rotated to align with the
• the split spherical pump housing 62 is assembled around the impeller 52 and pinned together circumferentially with the fasteners 63.
• the diffuser70 is attached to the pump housing 62 with the fasteners 78.
• the splined drive shaft 51 is assembled into the internally splined gear 101 trapping the water seal 79. Matching the internal spline in the pump hub cone to the splined shaft 51, the assembled pump 50 and diffuser 70 slide onto the splined shaft 51 370 and are attached to the grate structure 40 with the fasteners 64.
• Internal to the splined shaft 51 is the pushrod 65, which acts on the spider 55.
• a vane adjustment means is connected to the pump impeller 52 for controlling pitch of the pump vanes 57, and, hence, the most efficient flow rate of the pump 50. As shown in FIGS. 2, 3, 4 and 5, the vane adjustment means
• the 375 includes the hydraulic cylinder assembly 102 internal to the driven gear 101.
• the hydraulic cylinder assembly 102 is solidly mounted to the bell housing 103 using the fasteners 104.
• the end piece 105 of the hydraulic cylinder assembly 102 incorporates a hydraulic fluid passage 107 and a square post 108, which fits a square hole in the piston 109 to prevent the rotation of the piston 109.
• the piston 109 acts on the roller thrust bearing 110.
• the bearing plate 111 engages the internal spline in the driven gear 101,
• variable rectangular steering nozzle 80 Located aft position of the pump's diffuser 70 is the variable rectangular steering nozzle 80.
• the nozzle 80 is formed between a top plate 81 and a bottom plate 82, which are held parallel by their attachment to the two wing walls 83.
• the nozzle vanes 84 have integral shafts 85.
• the shafts 85 are born by bearing holes in the top plate 81
• the nozzle vanes 84 are formed so that their top and bottom edges fit closely to the top plate 81 and bottom plate 82, respectively.
• the axes of the vane shafts 85 are held perpendicular to the plates 81 and 82, so that the rotation of the shafts 85 results in the movement of the vanes 84 between the plates 81 and 82, while maintaining close fits between the edges of the vanes 84 and the plates 81 and 82.
• a rectangular discharge opening 88 which is bounded by the plates 81 and 82 and the vanes 84.
• FIG. 8 shows top views of the nozzle 80, which shows how the angle of the nozzle vanes 84 can be controlled both to provide steering control and to reduce nozzle area.
• Each of the steering vanes is positioned by a hydraulic ram 91, which operates on the respective vane operating arm 92.
• the hydraulic nozzle cylinders 93 are mounted inside the transom 95, so that only the rams 91 penetrate the transom 95.
• FIG. 8A shows the nozzle vanes 84 in the wide-
• FIG. 8B shows the nozzle vanes 84 in the full low speed turn position turn position.
• Figure 8C shows the nozzle vanes 84 in the high-speed flow reduction position.
• FIG. 9 is a schematic of a hydraulic system for controlling the nozzle vanes 84 for steering, flow reduction, and nozzle azimuth simultaneously.
• the azimuth movement is commonly used in planing watercraft as a power trim to 405 adjust the planing angle of the boat, as is well understood in the art.
• the adjustment of the nozzle discharge angle in the vertical plane is also useful for reducing vortexing in the reverse mode.
• the double acting steering cylinders 93 penetrate the transom 95 with ball-ended fittings or rubber grommets, as is 410 common in the art, and are connected to the vane operating arms 92 with ball-ended couplings 94, as is common in the art.
• the hydraulic steering lines 121 and 122 are connected to a hydraulic helm 123, which is driven by the steering wheel 124, as is common in the art.
• the steering cylinders 93 are series connected for reverse action, so that the cylinders 93 move equal distances in opposite directions in response to fluid delivered from the hydraulic helm. This steering action can be seen to result in the common rotation of the vane shafts 85, until the steering 415 vanes 84 reach the position shown in FIG. 8(B).
• the balancing cylinder 125 of FIG. 9 is composed of three hydraulic cylinders in tandem.
• the driven cylinder 126 is single ended, and is so constructed that the area of the piston is twice the area of the shaft.
• the nozzle closing circuit 127 is connected on the closed end of the driven cylinder 126, so that the fluid displacement is proportionate
• the balancing circuit 128 is connected on the shaft side of the piston, so that the fluid displacement in the circuit 128 is equal to half of the displacement of the piston in the circuit 127 and opposite in direction.
• the balancing circuit connection 129 is made to tandem cylinder in the driven cylinder 130, so that the displacement is in the balancing circuit 129 is also equal to half of the displacement of the piston in the circuit 127 and opposite in direction. It can be seen that the result of this arrangement is that the steering cylinders 93 move in
• the driving hydraulic cylinder 133 controls the displacement of the driven cylinders 126 435 and 130.
• the driving cylinder 133 moves in response to two hydraulic power sources.
• the flow control valve 134 which is also shown in FIG.2, responds to commands from the microcontroller 150. It is a 4-way valve that controls the motion of the driving cylinder 133, as is common in the art. Through this means the microcontroller 150 acts to adjust the effective nozzle area of the rectangular discharge opening 89 in order to maintain the efficient operation of the spherical pump 50, as will be detailed below.
• the second hydraulic power source is a trim control 440 valve 135, which is controlled by the operator to adjust the azimuth of the nozzle 80 for power trim, as shown in
• FIG. 10 The hydraulic circuit from the trim control valve 135 is connected in series with the trim cylinder 136. It can be seen that the effect of this circuit is to displace the trim cylinder 136 and the driving hydraulic cylinder 133 in the same direction. As a result of the motion of the driving cylinder 133, the steering cylinders 93 are also displaced in the same direction. This common motion can be seen to reduce the effect of power trim adjustment on 445 the position of the nozzle vanes 84.
• FIGs. 10A and 10B are side elevation section views indicated on FIG. 1, showing the action of the optional trim cylinder 136 on the nozzle 80.
• the piston area of the trim cylinder 136 is so chosen relative to the piston area of the steering cylinders 93 and the driving cylinder 133 that the angular displacement of the connection points 136
• the action of the trim control valve 135 of FIG. 9 is to extend both the trim cylinder ram and the steering cylinder rams by a proportion that minimizes the effect of the trim movement on the steering and nozzle area control functions.
• the extreme down position of the trim range shown in FIG. 10B is useful in increasing submergence of the nozzle 80, which acts as a water inlet in the reverse mode.
• the nozzle guard 88 serves both to prevent vortex cavitation and to prevent human limbs and other objects from approaching
• Propulsion system efficiency is the product of four efficiency components: inlet duct, pump, nozzle, and engine.
• the nozzle has relatively small losses, which can be ignored without significant loss of system efficiency.
• the inlet duct recovery efficiency is maximized independently by maintaining the duct entrance velocity to approximate the
• FIG. 2 shows the schematic diagram connections of the microcontroller 140.
• the operator uses the single handle control 141 to control both propulsion direction and the throttle 142 for the engine 21, as is common in recreational boats.
• the single handle control 141 incorporates a throttle dead band, so that the throttle is set at idle from about
• the microcontroller 140 is programmed to position the vane actuator piston 109 through the hydraulic control module 157, so that the vane angle follows the position of the single handle control over the throttle dead band. 485 Another input to the microcontroller 140 shown in FIG. 2 is the head differential pressure transducer 145, which provides the difference between the pitot tube pressure 146 after the pump 50 and the pitot tube pressure 147 at the inlet of the pump 50. This difference is well understood in the hydraulic art to be the commonly accepted measure of the head h on the pump 50.
• Another input to the microcontroller 140 shown in FIG. 2 is the flow differential pressure transducer 149, which provides the difference between the inlet pitot tube pressure 147 and the inlet static pressure 150.
• the differential pressure on the transducer 149 is equal to the flow velocity V squared divided by twice the acceleration of gravity g, or V ⁇ 2/2g.
• speed pressure transducer 151 Another input to the microcontroller 140 shown in FIG. 2 is the speed pressure transducer 151, which provides the speedometer pitot tube pressure 152 from the boat speedometer pitot tube. For purposes of the calculations discussed below it is well known that this pressure is approximate to the speed of the water craft divided by twice 500 the acceleration of gravity, so the discussion in the previous paragraph also applies here.
• This tachometer input 154 is commonly a pulse train that is read with a timed counter integral to the microcontroller, as is well known in the art. 505
• Another input to the microcontroller 140 shown in FIG. 2 is the engine load signal 155, which is output by the engine combustion microcontroller. This interface is well known in the automotive art.
• the operator preference input 157 is a variable 510 resistance or optical encoder to indicate the operator preference for performance or economy operation.
• the microcontroller 140 has several control outputs, through which it controls the movement of the nozzle vanes 84, the pump impeller vanes 57, and the adjustable inlet slide 31.
• the operation of the flow control module 133 has been discussed in relation to FIG. 9 above.
• the balancing cylinder 125 of FIG. 9 has internal positional feedback to 515 the microcontroller 140, as is well known in the art.
• the inlet control module 159 uses hydraulic power and incorporates positional feedback.
• the vane hydraulic control module 158 also uses hydraulic power and incorporates positional feedback.
• the program for microcontroller 140 is a PICmicro ® Microcontroller, which is 520 available from Microchip Technology. Programs for these devices are developed using the Microchip's C programming environment. This development system is capable of incorporating a wide range of mathematical functions in the control program. The following paragraphs provide background on the functions to be incorporated in the control program. 525 The Basis of the Control Relationships
• FIG. 11 is a graph of shaft power versus shaft rpm, showing the relationship between pump shaft power demand and a typical engine's most efficient power supply.
• the gearing between the pump and engine is chosen so that pump power demand curve 160 intersects the engine power supply curve 161 at the highest allowable engine rpm, which is taken to be 5000 rpm in FIG. 11.
• the pump power demand curve 160 is approximately a cubic curve as shown in FIG. 11, as is well known in the art of pump design, and particularly in the area of pump affinity relationships.
• the difference between the most efficient power supply curve 161 and the pump power demand curve 160 is unfortunately greatest in the most frequent operating range, which falls between the horizontal lines 163 and 164.
• the engine 21 is operating furthest from its most efficient operating rpm most of the time.
• the full-pitch power curve 165 represents the power demand curve of the same pump 50 with the vanes 57 set at full pitch of about 40 degrees beta-2. It is well understood in the art of pump design that this range of efficient operation is common to variable pitch propeller pumps.
• the spherical pump 50 has the additional efficiency advantage of having close fits between the tips of the vanes 57 and
• the engine rpm is reduced from about 4,000 to about 2,600.
• One of these intermediate curves can be seen to be the most efficient for each possible engine rpm between 3,000 and 5,000 in FIG. 11.
• the curve 167 in FIG. 11 represents the power demand curve that can be achieved at somewhat reduced pump efficiency by either further increasing vane pitch or by reducing the nozzle area below that required to maintain the pump at its most efficient operating head and flow. In the preferred embodiment this occurs at low watercraft
• the nozzle 80 of the preferred embodiment is designed for a rectangular discharge opening 89 of 10" by 10", which is sufficient to maintain the pump at its most efficient operating point on the full-pitch curve 165 at a watercraft speed of 20 mph, where the inlet duct 30 is recovering about 12 feet of total dynamic head at the pump inlet.
• the maximum nozzle area restricts full-pitch pump flow.
• FIGS. 12, 13A, 13B, and 13C are flow diagrams for the microcontroller 140 program.
• the "d" values in FIGS. 12 and 13 are control dead band factors to prevent hunting, as is common in the art. These are discussed in the 590 Operation of the Invention below.
• the operation of the invention is controlled by the microcontroller 140 using the control program diagrammed in FIGs. 12 and 13.
• the physical components are shown in FIG.2.
• the control loop of FIG. 12 begins with reading the position P of the shaft encoder 143 on the single handle control 141. If P is in the throttle dead band range, the
• microcontroller 140 increments the vane hydraulic control module 158 to set the pitch of the impeller vanes 57 is set to follow P. This has the effect of giving the operator direct control over the forward or reverse flow through the pump 50.
• the concentric spherical surfaces of the split pump housing 62, the impeller vanes 57 and the spherical surface of impeller hub 53 allow the impeller vanes 57 to rotate through 90 degrees or more, while maintaining close fits between the vanes 57 and both housing 62 and the hub 53.
• the vane hydraulic control module 158 positions the piston 109 by controlling the flow of fluid through the hydraulic fluid passage 107.
• the piston 109 acts through the thrust bearing 110, the bearing plate 111, the pushrod 65, and the spider 55 to move the operating arms 56, which rotate the impeller vanes 57. If P is out of the dead band in reverse, the microcontroller 140 holds full reverse pitch on the vanes 57.
• the program of FIG. 12 branches to adjust the nozzle according to the pump head affinity relationship.
• the program of FIG. 12 then adjusts the inlet slide to match entrance velocity to boat speed, and passes control to 13A, 13B, or 13C for setting the pitch of the pump impeller vanes 57.
• the microcontroller program branches to the "Forward Mode" as shown in FIG. 12.
• the pump affinity relationship h kN ⁇ 2.
• control program sets the adjustable inlet slide 3 lto match the velocity of the inlet entrance flow 45 to the velocity of the water under the boat. This maintains the most efficient possible recovery of total dynamic head at the inlet of the pump 50.
• FIG. 13A sets the pitch of the impeller vanes 57 based on pump shaft power demand calculated from measured head and flow on the pump 50.
• FIG. 13B sets the pitch of the impeller vanes 57 based on throttle position as measured by the shaft position encoder 143 on the single handle control 141.
• FIG. 13C sets the pitch of the impeller vanes 57 based on feedback from the combustion controller 23 on the engine 21.
• each of these alternative 625 methods accomplishes the same function: they all adjust the pitch on the impeller vanes 57, so that the shaft power demand of the pump 50 approximates the most efficient power supplied by the engine 21 at its current rpm.
• the vane 57 pitch is about zero, which provides no pumping action and therefore a true neutral.
• the vane pitch is in the maximum negative position, which provides reverse thrust and back flushing of trash.
• the microcontroller 140 reads the head differential pressure sensor 145 to input the pump head h and the engine tachometer input 154 to input engine rpm 640 N. If the measured head is higher than the pump affinity value kN ⁇ 2 plus a small dead band factor d to prevent hunting, the microcontroller 140 uses the flow control module 133, which positions the driving cylinder 130 and consequently the driven cylinder 126, which forces fluid into the hydraulic circuits 128 and 129, while removing an equal amount of fluid from the hydraulic circuit 127. Following the explanation of FIG. 9 above, this results in a balanced fluid flow to the steering cylinders 93, so that the steering rams 91 are equally retracted, acting through
• the microcontroller 140 uses the flow control module 133, which positions the driving cylinder 130 and consequently the driven cylinder 126, which removes fluid from the
• the next sequence in the control loop of FIG. 12 is setting the inlet slide 131.
• the microcontroller 140 reads the position of the inlet slide cylinder 34 from the inlet control module 159 and computes the effective inlet entrance area. It reads the flow differential pressure transducer 149 and computes the system
• the microcontroller 140 reads the boat speed pressure transducer 151 and compares watercraft speed S. If V > S +d, the microcontroller 140 outputs to the inlet control module 159, which actuates the inlet cylinder 34 to move the adjustable inlet slide 31 back, which increases the effective entrance area and reduces the
• microcontroller 140 can also be programmed to calculate the system flow from positional feedback from the vane control module 157 on the angle of the impeller vanes 57, which would allow the elimination of the flow pressure transducer 149 input in the control loop.
• FIG. 13A At the end of FIG. 12 the microcontroller program control passes to FIG. 13A, 13B, or 13C to match the pump 50 675 power demand to the power most efficiently supplied by the engine 21 by varying the pitch of the impeller vanes 57.
• the control scheme in FIG. 13A first computes the hydraulic power produced by the pump 50, which is the product of pump head h and system mass flow rate q.
• the pump shaft power demand is the hydraulic power divided by the
• control loop uses a table of vane pitch targets T, which is entered with control position C.
• the T values include adjustments for pump efficiency variations and other factors based on test results.
• the control position C is a measure of the engine throttle 142 setting, which has an associated most efficient operating rpm. This rpm is implicitly included in the table of values for T, which is entered with C. It will be
• the microcontroller program sets the vane pitch to T. This method presumes that the engine is operating at peak performance.
• the operator preference input 157 may be used to reduce the shaft power demand when the engine is out of tune or laboring. It may also be used to choose between low-speed performance and fuel economy, as is common in automotive power transmission. This preference factor
• FIG. 13C uses the output from the combustion microcontroller on the engine 21 as the best measure of the power most efficiently supplied by the engine at the current shaft rpm, which is shown as 23 on FIG. 2.
• This control method is well understood in the automotive field of art, as it is widely used to determine shift points in automatic transmission controllers and to control continuously variable transmissions.
• the microcontroller 140 is
• the microcontroller 140 In each control cycle the microcontroller 140 incrementally increases, decreases, or leaves unchanged the impeller pitch, based solely on the input from the combustion microcontroller. This method requires no pump head input, no rpm input, no system flow input and no positional feedback for controlling the impeller
• FIG. 13C requires neither flow measurement nor vane positional feedback, because it incorporates control feedback from the engine combustion control computer.
• the direct flow measurement means is not required in the "Set Vane Angle" control sequence, as in FIG. 13C or when flow is estimated by vane 57 pitch, it can be compared with the positional feedback from the vane angle to monitor the operating efficiency of the marine jet propulsion system 20. If the calculated flow is lower than that indicated by the vane position, the likely cause is debris on the inlet vanes 42, pump impeller vanes 57, and/or stator vanes 71.
• the microcontroller 140 can be programmed to alert the operator by some alarm means, such as a light or a horn.
• the microcontroller 140 is programmed to adjust the pitch of the impeller vanes 57 through the hydraulic control module 158, so that the pump 50 shaft power demand is made to approximate the most efficient power supplied by the engine 21 at the current shaft rpm.
• the microcontroller 140 When the operator switches the ignition on, the microcontroller 140 outputs to the vane control module 158 to set the impeller vane 57 pitch to the position indicated by the shaft encoder 143 on the single handle control 141, which is generally zero pitch for neutral pump flow. The operator then starts the engine 21, which idles at about 1,000 rpm. In response to the movement of the single handle control 141 in the +/- 10-degree dead band range, the microcontroller 140 adjusts the impeller vane 57 angle to continuously vary the forward, neutral, and reverse thrust of the marine jet propulsion system 20, as detailed in FIG. 12 and the associated discussion above. Moving the handle through the straight up position results in a scissoring action between the pump vanes, which cleans debris off the leading edges of the vanes.
• Moving the handle further back results in reverse pitch and in reversing the pump flow, which back flushes the system for trash removal.
• Such reverse pump flow also produces an effective reverse thrust.
• Moving the handle 141 back further increases engine rpm and consequently the magnitude of the reverse thrust, just as is common in propeller driven boats.
• the swim platform and power trim function which are both popular on recreational boats of the prior art, may be used to reduce vortex formation and cavitation in the reverse thrust mode, as shown in FIG. 10.
• the operator independently controls power trim, just as in stern-drive and outboard propulsion systems of the prior art.
• the steering wheel controls the action of the nozzle vanes 84 through the range of motion shown in FIG. 8A and 8B through the hydraulic helm and hydraulic circuits shown in FIG. 9 and described above.
• Turning the wheel 124 of FIG. 9 to the right results in the left position of the nozzle vanes 84 in FIG. SB.
• the resulting directional change of momentum of the system flow creates a reaction steermg force to the right along the transom 95, so that when the wheel is turned to the left as in FIG. 8B, the transom 95 is driven to the right.
• the reaction force resulting from 755 reverse system flow is in the same direction as with forward flow, so that the transom 95 always moves to the right when the wheel 124 is turned to the left.
• Such reaction forces are well understood in the hydraulic art.
• variable nozzle In the forward thrust mode of operation, the variable nozzle is controlled to maintain the most efficient head on the variable pitch impeller pump for the current shaft rpm, as is described in my the US Patent 5,679,035 and as further
• the microcontroller opens the variable steering nozzle to maximum.
• this control strategy has the fortunate consequence of providing maximum flow at low speeds for maximum propulsion efficiency.
• the flow through the maximum nozzle opening also occurs at the lowest possible velocity.
• motor efficiency, pump efficiency, and flow rate efficiency are all close to optimum, and wake turbulence is minimized.
• the microcontroller 140 When the system 20 is under full acceleration, as in pulling up a water skier, the microcontroller 140 will reduce the pitch on the impeller vanes 57 to match the pump's shaft power demand to the engine's 21 most efficient power supply at the instantaneous shaft rpm. The control system will also reduce the nozzle area 89 to maintain the most efficient head on the pump 50 for its current rpm.
• variable nozzle 80 is close to being fully open to maintain the most efficient pump head at the relatively low shaft rpm.
• the nozzle area 89 head-affinity control function implicitly accounts for higher inlet head at this boat speed, higher pump 50 head at the higher shaft rpm, 795 and the reduced flow 32 resulting from reduced pitch on the impeller vanes 57.
• the nozzle area 89 is reduced and the nozzle velocity relative to the boat velocity is increased.
• the nozzle velocity relative to the water 29 surface is reduced by the increased boat speed, so that the velocity of the jet relative to the water surface has only slightly increased.
• Wake turbulence is thereby only slightly increased, and the use of longer towropes at this higher boat speed makes wake turbulence less critical, since it has more time to dissipate 800 before the skier reaches it.
• 810 nozzle area 89 at top speed is also ideal for reducing the system flow rate 32, hence improving propulsion efficiency at the higher speed.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Hydraulic Turbines (AREA)
• Control Of Turbines (AREA)

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• 2003
  • 2003-12-10 NZ NZ541125A patent/NZ541125A/en not_active IP Right Cessation
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  • 2003-12-10 WO PCT/US2003/039296 patent/WO2004052721A2/en not_active Application Discontinuation
  • 2003-12-10 EP EP03796906A patent/EP1587732A4/de not_active Withdrawn
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