Patent Publication Number: US-6709303-B2

Title: Internal combustion engine control unit for jet propulsion type watercraft

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an internal combustion engine control unit for a jet propulsion type watercraft that is powered by a jet propulsion force, and more particularly to a personal watercraft (PWC) which is a jet propulsion type watercraft. 
     2. Description of the Background Art 
     FIG. 4 is a perspective view showing the general construction of a PWC which is a jet propulsion type watercraft as disclosed in, for example, U.S. Pat. No. 6,159,059. In the figure, reference number  1  denotes a hull of a PWC;  2  an internal combustion engine which is controlled by an internal combustion engine control unit (ECU, not shown) and that generates a jet propulsion force optimum for driving the PWC, thereby allowing the hull  1  to run. Reference number  3  denotes a throttle valve which adjusts a throttle of the engine  2 ;  4  an impeller which is directly connected to the engine  2  and makes water drawn from the front of the hull  1  function as a jet propulsion force;  5  a spouting nozzle which spouts jet water generated by the impeller  4 ; and  6  a steering nozzle which changes the direction of jet water spouted from the spouting nozzle  5 . 
     Reference number  7  denotes a steering handle which steers the direction of the hull  1  and that is coupled with the steering nozzle  6  through a steering cable  9 , and it is possible to stir the hull  1  by changing the spouting direction of jet water. Reference number  8  denotes a throttle lever which is coupled with the throttle valve  3  through a throttle cable  10  and can adjust the throttle. The steering handle  7  and the steering nozzle  6  can be coupled not only in the above-mentioned mechanical manner but also in an electric manner such that, for example, a turning angle position of the steering handle  7  is detected, and the steering nozzle  6  is moved by a motor based on the detected signal. 
     Next, the movement for changing the traveling direction of the hull  1  by a rider who operates the steering handle  7  will be explained with reference to FIG.  5 . As shown in FIG. 5A, when the traveling direction of PWC is straight, the rider keeps the steering handle  7  vertically with respect to the traveling direction of PWC. Here, the steering nozzle  6  coupled with the steering handle  7  through the steering cable  9  is set exactly backward, and jet water is spouted backward to generate a jet propulsion force, thereby moving the PWC to move straight ahead. 
     On the other hand, as shown in FIG. 5B, in the case where it is intended to change the traveling direction of PWC to the left, when the rider turns the steering handle  7  to the left, the steering nozzle  6  moves to the right, and the spouting direction of jet water changes to the right, whereby the traveling direction of PWC can be changed to the left. Also, as shown in FIG. 5C, in the case where it is intended to change the traveling direction of PWC to the right, when the rider turns the steering handle  7  to the right, the steering nozzle  6  moves to the left, and the spouting direction of jet water changes to the left, whereby the traveling direction of PWC can be changed to the right. 
     In general, it is arranged that the engine rotation speed is defined by a throttle operation performed by the rider. When the rider operates the throttle to open, the engine rotation speed is increased. Thus, the jet propulsion force of PWC is increased, whereby the jet propulsion force is enhanced to allow the PWC to run faster. On the other hand, when the rider operates the throttle to close, the engine rotation speed is in the idle state where it is low. Thus, the jet propulsion force of PWC is reduced, and the running speed is therefore decreased gradually to the state that the PWC stops. 
     The internal combustion engine control unit (ECU) controls ignition timing, an amount of fuel supply (an amount of fuel spouting and jetting timing), and an amount of auxiliary intake air for the optimum engine performance and characteristics with respect to the degree of opening the throttle, such that the rider can operate and drive the PWC easily. 
     In the conventional PWC, as the operation inherent to PWC, in order to change the traveling direction of the hull  1 , it is necessary to change the spouting direction of jet water. Such can be achieved by operating the steering handle  7 . However, when the jet water does not have a propulsion force reaching a predetermined value, the traveling direction of PWC cannot be changed. In other words, it is necessary to operate the steering handle  7  under the condition where the throttle is opened and the engine rotates at a predetermined rotation speed or higher (the state that a jet propulsion force exists). However, even when the steering handle  7  is operated in the state that no jet propulsion force exists, there is an operational performance that it is impossible to change the traveling direction of the hull  1 . 
     When some risk is realized ahead in running, the steering handle  7  is generally turned to the right or to the left so as to change the traveling direction of PWC to avoid the risk. Here, when the engine rotation speed reaches a predetermined value, there is a jet propulsion force enough to change the traveling direction of PWC by the steering handle  7 , whereby the risk can be avoided. However, in the case where the risk is recognized when the throttle is nearly closed in the idle state, there was a problem that the risk cannot be avoided because, nevertheless the hull  1  runs at a certain speed by a remaining power depending on the engine rotation speed, a jet propulsion force enough to change the traveling direction of PWC by the steering handle  7  is not obtained. 
     In this case, it is necessary to open the throttle in addition to the steering handle operation. However, when a rider, especially a beginner, encounters a risk suddenly, he/she operates only the steering handle  7  in a fluster and forgets to open the throttle to generate the jet propulsion force, so that the risk cannot be avoided and a collision, for example, may occur. The PWC becomes popular because of the easier operation and the comfort, and the number of beginners increases, which also increases the number of this kind of accidents. 
     SUMMARY OF THE INVENTION 
     The present invention has been made to solve the above-described problems. An object of the present invention is to provide an internal combustion engine control unit for a jet propulsion type watercraft which can control an internal combustion engine so that a rider can avoid risks safely. 
     The internal combustion engine control unit for a jet propulsion type watercraft in accordance with the present invention provides an, includes a rotation speed detector which detects a rotation speed of the internal combustion engine, a throttle operation state detector which detects a state of the throttle operated by a rider, and a risk avoidance operation detector which detects that the rider operates an operation for risk avoidance. The internal combustion engine control unit further includes a controller which increases the rotation speed of the internal combustion engine, when, in a case where a throttle open degree detected by the throttle operation state detector is a predetermined value or lower, and it is judged that the jet propulsion type watercraft is running based on the rotation speed of the internal combustion engine detected by the rotation speed detector, the risk avoidance operation detector detects that the rider performs the risk avoidance operation. Thus, even when the watercraft is running in a state that a jet propulsion force enough to change the traveling direction by a steering handle is not obtained, the extra jet propulsion force which can change the traveling direction can be added quickly, so that the rider can perform the risk avoidance safely. 
     The internal combustion engine control unit of the present invention may further include an ignition timing controller which controls ignition timing for the internal combustion engine and a fuel supplying amount controller which controls a fuel supplying amount of supplied to the internal combustion engine, whereby the rotation speed of the internal combustion engine is increased by using at least one of the ignition timing controller and the fuel supplying amount controller. Thus, the time delay from the risk avoidance operation performed by the rider to the generation of the jet propulsion force upon which the risk can be used actually avoided can be shortened. Then, the risk avoidance can be achieved safely in the shortest period of time. In addition, no additional devices for risk avoidance are needed, and an inexpensive system configuration can be realized. 
     In addition, the ignition timing is controlled to be earlier than usual. Thus, the engine rotation speed can be increased quickly. 
     The fuel supplying amount may be controlled to be larger than usual. Thus, the engine rotation speed can be increased quickly. 
     The fuel supplying amount is preferably controlled by making the fuel supplying timing earlier than usual. Thus, the engine rotation speed can be increased quickly. 
     The risk avoidance operation detector detects whether or not the rider has rapidly operated a steering handle. Thus, the risk avoidance operation by the rider can be detected quickly. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of the configuration of an internal combustion engine control unit for a jet propulsion type watercraft according to a preferred embodiment of the present invention. 
     FIG. 2 is a time-chart showing the movement of the internal combustion engine control unit for a jet propulsion type watercraft according to the preferred embodiment of the present invention. 
     FIG. 3 is a flowchart showing the movement of the internal combustion engine control unit for a jet propulsion type watercraft according to the preferred embodiment of the present invention. 
     FIG. 4 is a perspective view showing the general construction of a PWC in which the conventional internal combustion engine control unit for a jet propulsion type watercraft is mounted. 
     FIG. 5 is a movement view showing the steering operation for the PWC in which the internal combustion engine control unit for a jet propulsion type watercraft is mounted. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail with reference to the accompanying drawings. 
     FIG. 1 is a block diagram of the configuration of an internal combustion engine control unit for a jet propulsion type watercraft according to a preferred embodiment of the present invention. FIG. 2 is a time-chart showing the movement of the internal combustion engine control unit for a jet propulsion type watercraft according to the preferred embodiment of the present invention; and FIG. 3 is a flowchart thereof. Since the basic construction of a PWC controlled by the internal combustion engine control unit according to this embodiment is identical with that described in detail in FIG. 4 of the conventional example, the description will be omitted here. 
     In FIG. 1, reference number  21  denotes a steering handle angle detector which detects a turning angle of the steering handle  7  to generate a risk avoidance operational signal based on the detected turning angle, and configures a risk avoidance operation detector which detects a risk avoidance operation performed by a rider. Reference number  22  denotes a throttle open degree detector which detects a throttle open degree to generate a throttle open degree signal;  23  a throttle position signal generator which generates a throttle position signal based on the throttle open degree detected by the throttle open degree detector  22 . The throttle open degree detector  22  and the throttle position signal generator  23  configure a throttle operation state detector which detects the throttle operation state by the rider. In FIG. 2, which will be described below, a throttle position signal is generated under the condition where the throttle is closed fully. However, the throttle position signal may be generated when the throttle open degree is a predetermined value or below, that is, in the vicinity of the fully closed state. Furthermore, reference number  24  denotes a rotation speed signal detector which detects a rotation speed of the engine  2  to generate an engine rotation speed signal. 
     Reference number  25  denotes an ignition timing controller and, for example, controls an ignition coil which generates a high voltage in an ignition plug mounted in the engine  2 . Reference number  26  denotes a fuel supplying amount controller which controls an amount of fuel supply and timing for supplying fuel to the engine  2  and is, for example, an injector. Reference number  27  denotes a throttle valve open degree driver which controls the throttle open degree by driving a throttle valve which adjusts an amount of intake air of the engine  2 ;  28  an auxiliary intake air amount controller which controls an amount of intake air (bypass intake air amount) to the engine  2 . 
     Reference numbers  31   a  to  31   d  denote input circuits for inputting signals detected by the above-described various detectors to a microcomputer  30 ;  32   a  to  32   d  denote output circuits for outputting control signals to the above-described various detectors from the microcomputer  30 . The microcomputer  30 , the input circuits  31   a  to  31   d  and the output circuits  32   a  to  32   d  configure a controller  300 . 
     Next, the movement will be described with reference to FIG.  2 . In FIG. 2, the solid lines show the internal combustion engine control unit according to this embodiment; the broken lines show the conventional internal combustion engine control unit. In a usual running state, a rider opens the throttle so that the optimum running speed is obtained, and the engine rotation speed is a predetermined value, whereby the jet propulsion force is the optimum output. Here, the ignition timing and the fuel supplying amount are controlled by the controller  300  optimally so that the engine  2  can produce the optimum characteristics. In general, the ignition timing tends to be earlier, and the fuel supplying amount tends to be larger. 
     When the rider operates the steering handle  7  under the condition described above, the spouting nozzle  6  for jet water moves in cooperation with the operation of the steering handle  7 , and the spouting direction of jet water changes, so that the traveling direction can be changed to the operational direction of the rider. However, when the throttle is closed while running, it is judged that the rider has operated to reduce the running speed. Then, in the conventional example as indicated by the broken lines, the ignition timing and the fuel supplying amount are controlled to reduce the engine rotation speed. Thus, the engine rotation speed is reduced to the idle rotation speed when the throttle is fully closed. The jet propulsion force is also reduced at the idle rotation speed. Accordingly, it is impossible to change the traveling direction by the steering operation even while the hull  1  is running at a certain speed by using remaining power. 
     On the other hand, in this embodiment as indicated by the solid lines, when the throttle is closed fully while running, that is, when the throttle position signals are changed from “0” to “1” indicating the full close, and when, for example, the rider turns the steering handle  7  to the right or to the left rapidly to avoid the detected risk ahead, the steering handle angle signal detector  21  generates risk avoidance operation signals (from “0” to “1”). The risk avoidance operation signals may be generated when the steering handle  7  is turned by a predetermined angle or larger to the right or to the left during a predetermined period of time, or when the steering handle  7  is turned to the maximum position in the right direction or in the left direction during a predetermined period of time. When the microcomputer  30  detects such a state, the microcomputer  30  judges it as the risk avoidance mode and controls over the risk avoidance. 
     The control over the risk avoidance needs to be as good in responsiveness as possible. In this embodiment, the ignition timing and the fuel supplying amount, both of which directly control the combustion state in the engine  2  through the microcomputer  30 , are controlled to the optimum values, so that the engine rotation speed can be increased to a predetermined value (about 2,000 r/min). Specifically, the ignition timing and the fuel jet timing are controlled to be earlier, and the fuel supplying amount is controlled to be larger. Further, by changing the ignition timing, the fuel supplying amount and the fuel jet timing stepwise and rapidly, the combustion in the internal combustion engine changes rapidly, which can increase the engine rotation speed in a short period of time. 
     The engine rotation speed is smoothly increased to the predetermined value so as to increase the propulsion force of the hull. Thus, it is possible to change the traveling direction of the steering handle  7  and avoid the risk. Then, the hull  1  can be stopped by returning the ignition timing, the fuel supplying amount and the fuel jet timing to usual control values after the risk avoidance has been achieved. Whether the risk avoidance has been completed or not may be judged after lapsing a predetermined period of time T after the detection of the risk avoidance operation, or when the steering handle  7  is returned. 
     When the throttle is opened in addition to the steering handle operation for the risk avoidance, needless to say, the control over the throttle opening operation and the risk avoidance operation are performed together, so that more stable and smooth operations can be achieved. 
     Next, the movement by the controller  300  will be described with reference to the flowchart in FIG.  3 . First, whether or not the throttle is opened by a predetermined angle or larger (that is, whether or not the throttle is nearly closed) is judged (step S 1 ) based on throttle position signals generated from the throttle position signal generator  23  in response to the throttle open degree detected by the throttle open degree detector  22 . When the throttle is opened by the predetermined angle or larger, the usual control is performed because there is a jet propulsion force enough to change the traveling direction through the operation of the steering handle  7 . On the other hand, when the throttle is opened by the predetermined angle or smaller, it is judged whether or not the engine rotation speed is being reduced or is idle, that is, whether or not the hull  1  is running, based on signals from the rotation speed detector  24  (step S 2 ). When the engine rotation speed is not being reduced or is idle, usual control is performed because it is judged that the hull  1  is completely stopped, and there is no need for the risk avoidance operation. 
     On the other hand, when the engine rotation speed is being reduced or is idle, it is judged that the hull  1  is still running. Then, it is detected whether or not the steering handle  7  has been operated or turned rapidly based on risk avoidance operation signals from the steering handle angle detector  21  (step S 3 ). When the steering handle  7  is not rapidly operated or turned, it is judged that the rider does not perform the risk avoidance operation, and the usual control is performed. On the other hand, when the steering handle  7  is rapidly operated or turned, it is judged that the rider performs the risk avoidance operation and that the risk avoidance mode is entered. Then, control signals are output to the ignition timing controller  25  or the fuel supplying amount controller  26  to increase the engine rotation speed (step S 4 ). 
     According to this embodiment of the present invention, when the throttle is opened by the predetermined angle or smaller while the hull  1  is running, and when the risk avoidance operation performed by the rider is detected, the ignition timing and the fuel supplying amount are controlled to increase the engine rotation speed. Therefore, even while the hull  1  is running without a jet propulsion force enough to change the traveling direction by the steering handle  7 , the rider can perform the risk avoidance safely by quickly adding the jet propulsion force which can change the traveling direction. 
     Further, the internal combustion engine control unit (ECU) controls the state of the engine combustion optimally. Thus, the engine rotation speed can be increased immediately in response to the start of the control, which allows the smooth generation of the jet propulsion force enough to avoid the risk. That is, the time delay from the risk avoidance operation performed by the rider to the generation of the jet propulsion force upon which the risk can be actually avoided, can be shortened. Thus, the risk avoidance can be achieved safely in the shortest period of time. 
     An additional device, which can increase an amount of intake air to the engine  2 , such as a DC motor which can force to open or close the throttle valve and a device which controls an amount of bypass intake air, may be installed and operated. Thus, the engine rotation speed can also be increased to generate the jet propulsion force. However, the addition of devices causes not only the complexity in the system configuration and the higher cost, but also slower intake operations of air with lower responsiveness. Accordingly, like this embodiment, it is preferred to control the ignition timing and the fuel supplying amount to increase the engine rotation speed. 
     Further, the ignition timing controller  25  and the fuel supplying amount controller  26  are generally built in each of current ECU&#39;s. Therefore, no additional devices for risk avoidance are needed, and the inexpensive system can be configured. 
     Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.