Patent Publication Number: US-6663446-B2

Title: Method and system for controlling thrust of watercraft during various steering conditions

Description:
This application is a continuation of application Ser. No. 09/456,698 filed on Dec. 9, 1999. The present invention relates to a method and system for controlling the thrust of a watercraft during various steering conditions, and more particularly to a method and system for controlling the thrust of a watercraft of the jet propulsion type. 
    
    
     THE FIELD OF THE INVENTION 
     One type of watercraft is the jet-propelled type that is designed to be operated by a rider seated on the watercraft in a straddle-like fashion. This type of watercraft is propelled by discharging water out of a discharge nozzle located at the rear of the watercraft. 
     To provide steering for the watercraft, a steering nozzle is pivotably connected to the end of the discharge nozzle. The input for the pivot of the steering nozzle is provided by a steering handle pivotably mounted on the top of the watercraft. To steer the watercraft to the right, the rider turns the steering handle clockwise causing the steering nozzle to pivot counter-clockwise. The discharge of water out of the steering nozzle with the nozzle pivoted counter-clockwise causes the watercraft to yaw clockwise and turn to the right. A similar but opposite sequence is used to steer the watercraft to the left. Therefore, for a watercraft of the jet propulsion type to steer properly, a sufficient amount of thrust out of the steering nozzle is required. 
     The thrust of the watercraft is controlled by the rider through the use of a thumb operated throttle lever pivotably mounted on the steering handle. The throttle lever is biased toward an idle position. To increase thrust of water out of the discharge nozzle, the rider presses down on the throttle lever with his thumb. This pivots the throttle lever toward the wide-open throttle position. To decrease thrust of water out of the discharge nozzle, the rider releases the throttle lever. Since the throttle lever is biased toward the idle position, without a force countering the bias, the throttle lever pivots toward the idle position. As the throttle lever pivots toward the idle position, the thrust of water out of the discharge decreases. 
     While the decrease in thrust of water out of the discharge nozzle is desirable for slowing down the watercraft, the decrease in thrust of water out of the discharge nozzle also decreases the steering capability of the watercraft since the thrust provides the steering for the watercraft. 
     This quick decrease in steering capability is particularly problematic in situations in which an inexperienced rider attempts to avoid an obstacle directly in front of the watercraft. To properly avoid the obstacle, the rider should apply a constant pressure on the throttle lever while simultaneously turning the steering handle. However, an inexperienced rider may release the throttle lever to slow the watercraft quickly while simultaneously turning the steering handle in an attempt to maneuver around the obstacle. In such a situation, the rider may not be able to maneuver around the obstacle since steering capability has been decreased. 
     This decrease in steering capability is also problematic for the rider to maneuver the watercraft for docking the watercraft. Since the docking procedure usually occurs with the watercraft traveling at a low speed, the rider may release the throttle lever while attempting to dock the watercraft. However, with only idle thrust provided to steer the watercraft, steering capability may not be adequate to dock the watercraft. 
     SUMMARY OF THE INVENTION 
     The present invention is directed toward a system for controlling thrust of a jet propulsion type watercraft during various steering conditions. The system comprises a thrust mechanism for providing jet propulsion thrust, an operator-controlled throttle control mechanism, a throttle control position sensor for sensing the position of the operator-controlled throttle control mechanism, a steering mechanism for directing the jet propulsion thrust to steer the watercraft, a steering position sensor for sensing the steering position of the steering mechanism of the watercraft and a controller for determining the desired jet propulsion thrust based on the position of the operator-controlled throttle control mechanism received from the throttle control position sensor and/or the position of the steering mechanism received from the steering position sensor. The controller causes the thrust mechanism to increase thrust to a steerable thrust or inhibits the thrust from decreasing below a steerable thrust. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a watercraft in accordance to the present invention; 
     FIG. 2 is an enlarged view of the right steering handle of FIG. 1; 
     FIG. 3 is an enlarged view of the throttle regulation of FIG. 1; 
     FIG. 4 is a top plan view of the steering post and proximity switch of FIG. 1; 
     FIG. 5 is a schematic diagram of a first embodiment of the present invention; 
     FIG. 6 is a diagram showing programmed throttle positions during a given time sequence in accordance with the first embodiment in which the throttle increases quickly to a throttle above idle throttle; 
     FIG. 7 is a diagram showing programmed throttle positions during a given time sequence in which the throttle increases quickly to a throttle above idle throttle; 
     FIG. 8 is a diagram showing throttle positions remaining at a throttle above throttle until the steering handle has been turned sufficiently toward the straight-ahead position; 
     FIG. 9 is a schematic diagram of a second embodiment of the present invention; and 
     FIG. 10 is a flow diagram showing an exemplar programming for the controller in accordance with the second embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a watercraft  10  constructed in accordance to the present invention. The watercraft comprises a hull  12  that has a bow portion  14 . A steering handle  16  is pivotably mounted to the rear of the bow  14  and is part of a steering mechanism for steering the watercraft. The steering mechanism includes the steering handle  16  and a steering post  90  in which the steering handle  16  is fixed to the steering post  90  such that the steering post  90  pivots the steering handle  16 . 
     The watercraft  10  is powered by an internal combustion engine  18  that is contained beneath the bow  14  and which drives a jet propulsion unit  20  that is disposed centrally of the hull and beneath the seat  22 . The jet propulsion unit  20  includes an impeller  24  which draws water from a water inlet (not shown) and discharges the water through a discharge nozzle  26  and steering nozzle  28 . The steering nozzle  28  is supported for pivotal movement about a generally vertical extending axis  30  relative to the discharge nozzle  26  for steering the watercraft  10 . By pivoting the steering nozzle  28  about the vertical extending axis  30 , a turning force is created on the watercraft. 
     The steering post  90  is mechanically linked through a steering cable  32  to the steering nozzle  28  such that a rotational movement of the steering handle  16  will cause a pivotal movement of the steering nozzle  28 . For the rider to turn the watercraft  10  toward the right R, the rider would rotate the steering handle  16  clockwise W 1 . The clockwise rotation W 1  of the steering handle  16  causes the steering nozzle  28  to pivot counter-clockwise W 2 . The thrust of water out of the steering nozzle  28  with the steering nozzle  28  pivoted counter-clockwise W 2  causes the watercraft  10  to yaw clockwise W 3 , thus pivoting the front of the watercraft  10  to the right R. 
     Similarly for the rider to turn the watercraft  10  toward the left L, the rider would rotate the steering handle  16  counter-clockwise W 4 . The counter-clockwise W 4  rotation of the steering handle  16  causes the steering nozzle  28  to pivot clockwise W 5 . The thrust of water out of the steering nozzle  28  with the steering nozzle pivoted clockwise W 5  causes the watercraft  10  to yaw counter-clockwise W 6  thus pointing the front of the watercraft  10  to the left L. 
     Hence, the turning capability for this type of watercraft is created from the yaw of the watercraft caused by the thrust of water out the steering nozzle with the steering nozzle pivoted toward at a certain direction. The amount of yaw is a function of both the pivot of the steering nozzle and the thrust of the water out of the steering nozzle. Therefore, even if the steering nozzle is pivoted, without sufficient thrust of water out of the steering nozzle, the watercraft is not able to yaw and turn. 
     As illustrated in detail in FIG. 2, the rider controls the thrust of water out of the discharge nozzle through the use of a throttle lever  34  pivotably mounted to throttle lever bracket  36  attached to the circumferentially outer surface of the right portion of the steering handle  16  adjacent to a right handle grip  38 . The throttle lever  34  and the throttle lever bracket  36  are mounted to the steering handle  16  with the pivot end  40  axially away from the right hand grip  38  and the lever end  42  axially toward the right hand grip  38 . The right handle grip  38  and the throttle lever  34  are designed such that the rider&#39;s palm and four fingers rest on the hand grip  38  and the rider&#39;s thumb is positioned over the lever end  42  of the throttle lever  34 . 
     As illustrated in FIG. 1, the throttle lever  34  is mechanically linked through a throttle cable  44  to a throttle regulator  46 . The throttle regulator can be a carburetor for a carbureted internal combustion engine or a throttle body for a fuel injected internal combustion engine. As illustrated in detail in FIG. 3, the end of the throttle cable  44  is attached to a throttle control pulley  48  which is attached to a throttle plate  47  which regulates the amount of fuel and air provided to the combustion chamber of the internal combustion engine  18 . A throttle return spring  49  is attached to the throttle control pulley  48  to bias the throttle plate  47  toward an idle position. Since the throttle lever  34  is mechanically linked to the throttle control pulley  48  of the throttle regulator, the throttle return spring  49  likewise biases the throttle lever  34  toward an idle position. 
     To increase the thrust of water out of the discharge nozzle  26 , the rider would press down on the throttle lever  34  with his right thumb. This downward force counters the bias by the throttle return spring  49  and pivots the throttle lever  34  away from the idle position W 7  toward a wide open throttle position W 8  The rider can vary the amount of thrust out of the discharge nozzle by varying the amount of force applied on the throttle lever  34 . The more force applied on the throttle lever  34 , the more the throttle lever pivots from the idle position W 7  toward the wide open throttle position W 8  and pulls the throttle plate  47  of the throttle regulator toward the wide open throttle position W 10 . 
     To reduce the thrust of water out of the discharge nozzle  26 , the rider would apply a pressure on the throttle lever less than the bias caused by the throttle return spring  49 . This allows the throttle lever  34  to pivot toward the idle position W 7  and, likewise, the throttle plate  47  of the throttle regulator toward the idle position W 9 . The quickest way to reduce the thrust of water out of the discharge nozzle  26  is for the rider to totally release the throttle lever  34 , thus allowing the throttle return spring  49  to quickly bias the throttle lever  34  and the throttle plate  47  of the throttle regulator toward the idle positions W 7  and W 9 . 
     However, by quickly reducing the thrust of the water out of the discharge nozzle  26  by totally releasing the throttle lever  34  also quickly reduces the ability for the rider to steer the watercraft. As discussed earlier, steering of the watercraft  10  is caused by a thrust of water out of the steering nozzle  28  with the steering nozzle pivoted toward one direction, thus creating a yaw to the watercraft  10 . As the amount of thrust is decreased, the amount of yaw is also decreased. This is particularly problematic when an inexperienced rider seeks to avoid hitting an obstacle directly in front of the watercraft. 
     To avoid the obstacle directly in front of the watercraft, the rider should turn the steering handle toward one direction while simultaneously applying pressure on the throttle lever. This procedure provides sufficient thrust out of the steering nozzle for creating an adequate yaw of the watercraft to steer clear of the obstacle. However, an inexperienced rider may panic and quickly release the throttle lever to reduce the thrust of water out of the discharge nozzle. While the velocity of the watercraft is reduced, the reduction of thrust of water out of the steering nozzle also reduces the yaw of the watercraft, therefore reducing the steering capability of the watercraft. Without adequate steering capability, the momentum of the watercraft could force the watercraft into the obstacle. 
     FIG. 5 is a schematic of a first embodiment of the present invention. The present invention includes a system  100  for controlling the thrust of a watercraft during various steering conditions with inputs provided by the throttle position sensor  102  and the steering position sensor  104 . The system  100  for controlling the thrust is attached to the throttle regulator  46  to provide the watercraft with adequate steering capability even if the rider releases the throttle lever  34 . 
     The system  100  for controlling the thrust of the fifth embodiment comprises a throttle position sensor  102 , a steering position sensor  104 , a servomotor  106  and a microprocessor based controller  108 . The throttle position sensor  102  is located at the throttle regulator  46  at either the throttle control pulley  48  or the throttle plate  47 . The throttle position sensor  102  is electrically connected to the controller  108  and sends a signal to the controller  108  providing the throttle position. While the preferred embodiment illustrates the throttle position sensor  102  located at the throttle regulator  46 , the throttle position sensor  102  can be located anywhere from the throttle lever  34  to the throttle regulator  46 . 
     As illustrated in FIG. 4, the steering position sensor  104  comprises a proximity switch  84  and a proximity switch triggering mechanism. The proximity switch  84  is mounted on a bracket located near the steering post  90  of the watercraft. Two magnets  86  and  87  acting as proximity-triggering mechanisms are mounted on the steering post  90 . The magnets  86  and  87  are mounted on the steering post  90  such that the proximity switch  84  is located at the circumferential center of the two magnets  86  and  87  when the position of the steering post  90  causes the watercraft to travel in a straight direction. In other words, when the watercraft is traveling in a straight direction, the angle W 13  between the proximity switch  84  with one of the magnets  86  is approximately equal to the angle W 14  between the proximity switch  84  with the other magnet  87 . Once the proximity switch  84  is at a given trigger angular position P 1  or P 2 , the proximity switch  84  is sufficiently close to one of the magnets  86  and  87  to send a signal to the controller. 
     Thus, after the controller  108  receives inputs from the throttle sensor  102  that the throttle is sufficiently closed as to be unable to provide adequate steering thrust, and from the steering sensor  104  that the steering handle  16  has been sufficiently turned, the controller  108  sends a series of signals to the servomotor  106  in accordance with programmed throttle positions during a given time sequence. The servomotor  106  turns the throttle pulley  48  toward the wide open throttle position W 12  and opens the throttle plate  47  toward the wide open throttle position W 10  in accordance to the programmed throttle position during the given time sequence. 
     The programmed throttle positions during the given time sequence vary between watercrafts having different hull  12  and steering nozzle  28  designs. The programmed throttle positions during a given time sequence also vary between watercrafts having different desired performance outcomes. FIGS. 6 and 7 are exemplars of such programmed throttle positions during a given time sequence. FIG. 6 illustrates that upon the throttle released and the steering handle sufficiently turned at time t 1 , the throttle increases quickly to a throttle T 2  above idle throttle T 1  and then decreasing slowly to the idle throttle T 1 . The programmed throttle positions during a given time sequence (t 2 −t 1 ), as illustrated in FIG. 6, are ideal for a watercraft needing quick response such as performance oriented watercraft. This is also ideal for a watercraft less responsive to throttle, such as having a shallow hull, a long hull or a low pressured steering nozzle design. 
     FIG. 7 illustrates that upon the throttle released and the steering handle sufficiently turned at time t 3 , the throttle increases slowly to a throttle T 4  above idle throttle T 3  and then decreasing slowly to the idle throttle T 3 . The programmed throttle positions during a given time sequence (t 4 −t 3 ), as illustrated in FIG. 7, are ideal for a watercraft used for riders wanting a smooth and gradual thrust response. This is also ideal for a watercraft very responsive to throttle input such as having a deep hull, a short hull or a high-pressure steering nozzle design. 
     As illustrated in FIG. 8, the controller  108  can also be programmed to send a signal to the servomotor  106  upon the throttle released and the steering handle sufficiently turned at time t 5  to increase throttle to a first throttle T 6  above idle throttle T 5  and the decrease to a lower throttle T 7  above idle throttle T 5 . Thereafter, the throttle remains at the lower throttle T 7  above idle throttle T 5  until the steering handle  16  has been turned sufficiently toward the straight-ahead position at time t 6 , such that the steering position no longer surpasses steering position P 1  or P 2 , thereafter the throttle decreases to the idle throttle T 5 . This program allows the watercraft to turn quickly upon the steering handle  16  first being turned and thereafter remains at a smoother turn until the steering handle  16  has been turned sufficiently toward the straight-ahead pattern. 
     In short, a programmed controller of the first embodiment allows for variable throttle over a given time period upon certain required inputs sent by the throttle position sensor  102  and the steering position sensor  104 . 
     FIG. 9 is a schematic of a second embodiment of the present invention. The present invention includes a system  150  for controlling the thrust of a watercraft during various steering conditions with inputs provided by the throttle position sensor  152 , the steering position sensor  154 , the hull speed sensor  156  and the engine speed sensor  158 . The system for controlling the thrust is attached to the throttle regulator  46  to provide the watercraft with adequate steering capability even if the rider releases the throttle lever  34 . 
     The system  150  for controlling the thrust of the second embodiment comprises a throttle position sensor  152 , a steering position sensor  154 , a hull speed sensor  156 , an engine speed sensor  158 , a servomotor  160  and a microprocessor-based controller  162 . The throttle position sensor  152  is located at the throttle regulator  46  at either the throttle control pulley  48  or the throttle plate  47 . The throttle position sensor  152  is electrically connected to the controller  162  and sends a signal to the controller  162  providing the throttle position. While the preferred embodiment illustrates the throttle position sensor  152  located at the throttle regulator  46 , the throttle position sensor  152  can be located anywhere from the throttle lever  34  to the throttle regulator  46 . 
     As illustrated in FIG. 4, the steering position sensor  152  comprises a proximity switch  84  and a proximity switch triggering mechanism. The proximity switch  84  is mounted on a bracket located near the steering post  90  of the watercraft. Two magnets  86  and  87  acting as proximity-triggering mechanisms are mounted on the steering post  90 . The magnets  86  and  87  are mounted on the steering post  90  such that the proximity switch  84  is located at the circumferential center of the two magnets  86  and  87  when the position of the steering post  90  causes the watercraft to travel in a straight direction. In other words, when the watercraft is traveling in a straight direction the angle W 13  between the proximity switch  84  with one of the magnets  86  is approximately equal to the angle W 14  between the proximity switch  84  with the other magnet  87 . Once the proximity switch  84  is at a given trigger angular position P 1  or P 2 , the proximity switch  84  is sufficiently close to one of the magnets  86  and  87  to send a signal to the controller that the steering handle is sufficiently turned. 
     The hull speed sensor  156  can be a paddle wheel or a pitot tube. A paddle wheel is preferred since greater accuracy can be obtained by a paddle wheel. The hull speed sensor  156  can be located anywhere along the submerged portion of the hull  12 . The hull speed sensor  156  sends a signal to the controller  162  providing the speed of the hull relative to the surrounding water. The engine speed sensor  158  can be the same sensor which normally sends a signal to the tachometer informing the rider of the engine speed. In addition to sending a signal to the tachometer, the engine speed sensor  158  also sends a signal to the controller providing the engine speed. 
     After the controller  162  receives inputs from the throttle position sensor  152  that the throttle is sufficiently closed as to be unable to provide adequate steering, and from the steering position sensor  154  that the steering handle  16  has been sufficiently turned, with input of the hull speed received from the hull speed sensor  156  and input of the engine speed received from the engine speed sensor  158 , the controller  162  calculates a throttle position that the throttle regulator  46  should operate to obtain the desired water thrust out of the steering nozzle  28 . Therefore, the calculated throttle position is a function of the hull speed and the engine speed. The formula for calculating the throttle position would vary from one watercraft to another. Examples of such variations between the watercraft include the length of the watercraft, the width of the watercraft, the hull depth of the watercraft and the desired performance of the watercraft. 
     With the programmed formula for calculating the throttle position, the controller  162  continuously calculates the throttle position using inputs from the hull speed sensor  156  and the engine speed sensor  158 . The controller  162  then sends a signal to the servomotor  160  in accordance with the calculated throttle position. The servomotor  160  turns the throttle pulley  48  and opens the throttle plate  47  in accordance to the calculated throttle position. The controller  160  continuously calculates a new throttle position using inputs from the hull speed sensor  156  and the engine speed sensor  158  so long as the steering handle  16  is sufficiently turned and the throttle position is less that what is required to produce a steerable thrust. The time period between each calculation is dictated by the type of controller used. It is desirable to have small time periods between each calculation. However, a faster and more costly controller is required. Therefore, the time period between each calculation would depend on the cost effectiveness of the controller at the time the watercraft is designed. 
     It should be noted that while the controller  162  of the present invention calculates the throttle position based on the hull speed and the engine speed, it is not necessary that both the hull speed and the engine speed must be inputs for the controller  162  to operate. For example, the hull speed sensor  156  can be eliminated from the present invention and a constant value can be used in the formula for calculating the throttle position in place of a varying hull speed. Likewise, the engine speed sensor  158  can be eliminated from the present invention and a constant value can be used in the formula for calculating the throttle position in place of a varying engine speed. 
     The controllers  162  of the first and second embodiments also allow for several backup features to be designed into the throttle system. As illustrated in FIGS. 5 and 9, a back-up throttle return system  164  is located between the controller  162  and servomotor  160 . The back-up throttle return system  164  senses the signal from the controller  162  to the servomotor  160 . Should the controller  162  fail to send a signal to the servomotor  160 , the back-up throttle return system  164  causes the servomotor  160  to actuate the throttle regulator  46  to an idle position W 9 . Therefore, should the controller  162  malfunction, or the power source to the controller  162  fail, the back-up throttle return system  164  automatically returns the throttle regulator  46  to the idle position W 9  from the throttle position of the throttle regulator when the controller  162  fails to send a signal to the servomotor  160 . 
     Another backup feature of the second embodiment is an acceleration prevention system  166 . For some non-performance oriented watercrafts, acceleration during turning is undesirable since acceleration during turning may cause the rider to over-steer the watercraft. The controller  162  of the present invention, with the acceleration prevention feature  166 , checks the current hull speed of the watercraft against an average of the previous hull speed of the watercraft. Should the current hull speed be greater than the average of the previous hull speed, the controller  162  causes the throttle regulator  46  to reduce the water thrust out of the steering nozzle until the current hull speed is no longer greater than the average of the previous hull speed. Should the current hull speed fail to be reduced, such that the current hull speed is no longer greater than the average of the previous hull speed after a given amount of time, the back-up throttle return system  164  is activated to return the throttle regulator  46  to idle throttle W 9 . Should the back-up throttle return system  164  also fail to reduce the current hull speed such that the current hull speed is no longer greater than the average of the previous hull after a given amount of time, an engine kill switch  168  is activated to stop the engine  18  completely. 
     As further diagramed in FIGS. 5 and 9, additional features can be provided to the system for controlling the thrust of the watercraft. These additional features include a poor steering lite  170 , a steer active lite  172  and a fail lite  174 . Upon the controller  162  determining the steering handle  16  has been sufficiently turned and the throttle position below a position that would provide adequate steering thrust, the controller  162  sends power to the poor steering conditions lite  170  to inform the rider that the watercraft is experiencing poor steering condition. During the time period the controller  162  activates the servomotor  160 , the controller  162  sends power to the steering active lite  172  to inform the rider that the system for controlling thrust has been activated. Should the back-up throttle return system  164  be activated due to the controller&#39;s failure to send a signal to the servomotor, or the watercraft continuing to accelerate during the turn after a given amount of time, the controller  164  sends power to the fail lite  174  to inform the rider that the off-throttle steering system has failed to operate properly. 
     FIG. 10 is a flow diagram showing an exemplar programming for the controller  162  in accordance with the second embodiment. 
     Various features of the present invention have been described with reference to the embodiments shown and described. It should be understood, however, that modifications may be made without departing from the spirit and scope of the invention as represented by the following claims.