Patent Description:
Generally, in a marine vessel, as the speed of a hull increases with increase in the throttle opening angle of an engine in a propulsion device, the hull eventually shifts from a hump state into a planing state. In a case where a sailing speed is equal to or higher than a predetermined speed when it is judged that the hull is in the planing state, a driving control apparatus disclosed in <CIT> uses this sailing speed as a target sailing speed to control the throttle opening angle.

When, for example, the marine vessel is maneuvered in shallows, the hull is required to plane as slowly as possible. However, if the throttle opening angle becomes too small, the hull cannot maintain its planing state, and on the other hand, if the throttle opening angle becomes too large, the speed of the hull becomes too high. It is difficult to manually adjust the throttle opening angle in order to keep the marine vessel planing at low speed. <CIT> discloses a control system for a marine vessel according to the preambles of independent claims <NUM>, <NUM> and <NUM>, and a control method for the marine vessel according to the preamble of independent claim <NUM>.

The present invention provides a control system for a marine vessel, a marine vessel, and a control method for the marine vessel which are capable of maintaining a planing state of a hull at relatively low speed.

Control systems vessel which are capable of maintaining the planing state of the hull at relatively low speed are defined in independent claims <NUM>, <NUM> and <NUM>. A control method capable of maintaining a planing state of a hull at relatively low speed is defined in independent claim <NUM>.

According to this arrangement, in a case where the predetermined mode is set and it is judged that the hull has shifted to the planing state, the opening angle adjustment unit is controlled so as to maintain the planing state of the hull even when the hull has decelerated. As a result, the planing state can be maintained at relatively low speed.

Further features of the present invention will become apparent from the following description of preferred embodiments with reference to the attached drawings.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

First, a description will be given of a preferred embodiment of the present invention. <FIG> is a top view of a marine vessel to which a control system for the marine vessel according to the preferred embodiment is applied. The marine vessel <NUM> has a hull <NUM>, a plurality of (for example, two) outboard motors <NUM> as marine propulsion devices mounted on the hull <NUM>, and a plurality of (for example, a pair of) trim tabs <NUM>. A central unit <NUM>, a steering wheel <NUM>, and a throttle lever <NUM> are provided in the vicinity of a cockpit in the hull <NUM>.

In the following description, a fore-and-aft direction, a crosswise direction, and a vertical direction mean a fore-and-aft direction, a crosswise direction, and a vertical direction, respectively, of the hull <NUM>. For example, as shown in <FIG>, a centerline C1 extending in the fore-and-aft direction of the hull <NUM> passes through the center of gravity G of the marine vessel <NUM>. The fore-and-aft direction is the direction along the centerline C1. Fore or front means a direction toward the upper side of <FIG> along the centerline C1. Aft or rear means the direction toward the lower side of <FIG> along the centerline C1. The crosswise direction is defined based on a direction when the hull <NUM> is viewed from the rear. The vertical direction is a direction vertical to the fore-and-aft direction and the crosswise direction.

The two outboard motors <NUM> are mounted side by side on a stern of the hull <NUM>. To distinguish the two outboard motors <NUM>, the one located on the port side is referred to as an "outboard motor 15A", and the one located on the starboard side is referred to as an "outboard motor 15B". The outboard motors 15A and 15B are mounted on the hull <NUM> via respective mounting units <NUM> (14A and 14B). The outboard motors 15A and 15B have respective engines <NUM> (16A and 16B) which are internal combustion engines. The outboard motors <NUM> each obtain a propulsive force from propellers (not illustrated) that are rotated by driving force of the respective engines <NUM>.

The mounting units 14A and 14B each include a swivel bracket, a cramp bracket, a steering shaft, and a tilt shaft (none of them is illustrated). The mounting units 14A and 14B further include respective power trim and tilt mechanisms (PTT mechanisms) <NUM> (23A and 23B) (<FIG>). Each of the PTT mechanisms <NUM> turns the corresponding outboard motor <NUM> about the tilt shaft. This makes it possible to change an inclination angle of the outboard motors <NUM> with respect to the hull <NUM>, and hence a trim adjustment can be made, and the outboard motors <NUM> can be tilted up and down. Moreover, each of the outboard motors <NUM> is turnable about a center of turn C2 (about the steering shaft) with respect to the swivel bracket. By operating the steering wheel <NUM>, each of the outboard motors <NUM> is turned about the center of turn C2 in the crosswise direction (direction R1). Thus, the marine vessel <NUM> is steered.

The pair of trim tabs <NUM> is attached to the stern on the port side and the starboard side such that it can swing about a swing axis C3. To distinguish the two trim tabs <NUM> from each other, the one located on the port side is referred to as a "trim tab 20A", and the one located on the starboard side is referred to as a "trim tab 20B".

<FIG> is a side view of the trim tab 20A attached to the hull <NUM>. The trim tabs 20A and 20B have the same construction, and hence the construction of only the trim tab 20A will be described. The trim tab 20A has a trim tab actuator 22A and a tab 21A. The tab 21A is attached to the rear of the hull <NUM> such that it can swing about the swing axis C3. For example, a base end portion of the tab 21A is attached to the rear of the hull <NUM>, and a free end portion of the tab 21A swings up and down (in a swinging direction R2) about the swing axis C3. The tab 21A is an example of a posture control member that controls the posture of the hull <NUM>.

The trim tab actuator 22A is disposed between the tab <NUM> and the hull <NUM> such that it connects the tab 21A and the hull <NUM> together. The trim tab actuator 22A drives the tab 21A to swing it with respect to the hull <NUM>. It should be noted that the tab 21A indicated by a chain double-dashed line in <FIG> is at a position where its free end portion is at the highest level (a position where the the amount by which the tabs <NUM> is lowered by <NUM>%), and this position corresponds to a retracted position. The tab 21A indicated by a solid line in <FIG> is at a position where its free end portion is at a lower level than the bottom (keel) of the marine vessel <NUM>. It should be noted that a range where the tab 21A is able to swing is not limited to the one illustrated in <FIG>. The swinging direction R2 is defined with reference to the swing axis C3. The swing axis C3 is perpendicular to the centerline C1 and parallel to, for example, the crosswise direction. It should be noted that the swing axis C3 may extend diagonally so as to cross the center of turn C2.

<FIG> is a block diagram of a maneuvering system. The maneuvering system includes the control system for the marine vessel according to the present preferred embodiment. The marine vessel <NUM> has a controller unit <NUM>, a throttle position sensor <NUM>, a steering angle sensor <NUM>, a hull speed sensor <NUM>, a hull acceleration sensor <NUM>, a posture sensor <NUM>, a receiving unit <NUM>, a display unit <NUM>, and a setting operation unit <NUM>. The marine vessel <NUM> also has engine rpm detection units <NUM> (17A and 17B), turning actuators <NUM> (24A and 24B), the PTT mechanisms <NUM> (23A and 23B), the trim tab actuators <NUM> (22A and 22B) (see <FIG> as well). The marine vessel <NUM> also has a throttle sensor <NUM> and an opening angle adjustment unit <NUM>.

The controller unit <NUM>, the throttle sensor <NUM>, the opening angle adjustment unit <NUM>, the steering angle sensor <NUM>, the hull speed sensor <NUM>, the hull acceleration sensor <NUM>, the posture sensor <NUM>, the receiving unit <NUM>, the display unit <NUM>, and the setting operation unit <NUM> are included in the central unit <NUM> or disposed in the vicinity of the central unit <NUM>. The turning actuators 24A and 24B and the PTT mechanisms 23A and 23B are provided for the outboard motors 15A and 15B, respectively. The throttle position sensor <NUM> and the engine rpm detection units <NUM> are provided in the respective outboard motor <NUM>. The trim tab actuators 22A and 22B are included in the trim tabs 20A and 20B, respectively.

The controller unit <NUM> includes a CPU <NUM>, a ROM <NUM>, a RAM <NUM>, and a timer which is not illustrated. The ROM <NUM> stores a control program. The CPU <NUM> expands the control program stored in the ROM <NUM> into the RAM <NUM> to implement various types of control processes. The RAM <NUM> provides a work area for the CPU <NUM> to execute the control program.

Results of detection by the sensors <NUM> and <NUM> to <NUM> and the engine rpm detection units <NUM> are supplied to the controller unit <NUM>. The throttle sensor <NUM> detects the operational position of the throttle lever <NUM> operated. The throttle position sensor <NUM> detects the opening angle of a throttle valve, which is not illustrated. The opening angle adjustment unit <NUM> adjusts the opening angle of the throttle valve. In normal control, the CPU <NUM> controls the opening angle adjustment unit <NUM> based on the operational position of the throttle lever <NUM>, and when a planing mode (a predetermined mode) (which will be described later) in which a planing state is maintained is applied, controls the opening angle adjustment unit <NUM> according to situations. Thus, in the planing mode, the operational position of the throttle lever <NUM> and the actual opening angle of the throttle valve do not always correspond to each other.

The steering angle sensor <NUM> detects the turn angle of the steering wheel <NUM> that has been turned. The hull speed sensor <NUM> and the hull acceleration sensor <NUM> detect the speed (vessel speed) and the acceleration, respectively, of the marine vessel <NUM> (the hull <NUM>) while it is traveling.

The posture sensor <NUM> includes, for example, a gyro sensor, a magnetic direction sensor, and so forth. Based on a signal output from the posture sensor <NUM>, the controller unit <NUM> calculates a roll angle, a pitch angle, and a yaw angle. It should be noted that the controller unit <NUM> may calculate the roll angle and the pitch angle based on a signal output from the hull acceleration sensor <NUM>. The receiving unit <NUM> includes a GNSS (Global Navigation Satellite Systems) receiver such as a GPS and has a function of receiving GPS signals and various types of signals as positional information. A signal received by the receiving unit <NUM> is supplied to the CPU <NUM>. From a speed restricted area or the ground in its vicinity, an identification signal for providing notification that the area is a speed restricted area is transmitted. The speed restricted area means an area in a harbor or the like which requires to limit the speed of a marine vessel to a predetermined speed or lower. The receiving unit <NUM> also has a function of receiving the identification signal. It should be noted that the acceleration of the hull <NUM> may also be obtained from a GPS signal received by the receiving unit <NUM>.

The engine rpm detection units <NUM> detect the number of revolutions per unit time of the respective engines <NUM> (hereafter referred to as "the engine rpm"). The display unit <NUM> displays various types of information. The setting operation unit <NUM> includes an operator by which a vessel operator performs operations relating to maneuvering, a PTT operation switch, a setting operator by which a vessel operator makes various settings, and an input operator by which a vessel operator inputs various types of instructions (none of them is illustrated).

The turning actuators <NUM> turn the respective outboard motors <NUM> about the respective centers of turn C2 with respect to the hull <NUM>. The turns of the outboard motors 15A and 15B about the respective centers of turn C2 can change the direction in which the propulsive force acts on the centerline C1 of the hull <NUM>. The PTT mechanisms <NUM> turn the respective outboard motors <NUM> about the tilt shaft to tilt the respective outboard motors <NUM> with respect to the cramp bracket. The PTT mechanisms <NUM> are operated by, for example, the PTT operation switch being operated. As a result, the inclination angles of the outboard motors <NUM> with respect to the hull <NUM> can be changed.

The trim tab actuators 22A and 22B are controlled by the controller unit <NUM>. For example, the controller unit <NUM> operates the trim tab actuators 22A and 22B by outputting control signals to them. The operation of each of the trim tab actuators 22A and 22B which are driving units causes the corresponding tab <NUM> to swing. It should be noted that actuators adopted for the PTT mechanisms <NUM> or the trim tab actuators 22A and 22B may be either a hydraulic type or an electric type.

It should be noted that the controller unit <NUM> may obtain results of detection by the engine rpm detection unit <NUM> via a remote control ECU, which is not illustrated. It should be noted that the controller unit <NUM> may also control the engines <NUM> via outboard motor ECUs (not illustrated) provided in the respective outboard motors <NUM>.

A signal output from the posture sensor <NUM> is also used to detect a turning state. The signal output from the posture sensor <NUM> includes a yaw rate (yaw turn angular velocity) which is an angular velocity of turn around a yaw axis. Based on the yaw rate output from the posture sensor <NUM>, the CPU <NUM> judges whether or not a traveling direction of the hull <NUM> is a straight traveling direction. When the yaw rate is equal to or smaller than a predetermined value, the CPU <NUM> judges that the traveling direction of the hull <NUM> is the straight traveling direction, and when the yaw rate is greater than the predetermined value, the CPU <NUM> judges that the traveling direction of the hull <NUM> is a turning direction. It should be noted that the CPU <NUM> may judge whether or not the traveling direction of the hull <NUM> has changed, based on time-series data on the yaw angle obtained from the magnetic direction sensor of the posture sensor <NUM>. It should be noted that in the present preferred embodiment, it is not absolutely necessary to detect the turning state.

<FIG> is a view showing the relationship between vessel speed and pitch angle. The throttle opening angle of the engine <NUM> in the outboard motor <NUM> is increased from a stopped state of the hull <NUM>, and the hull <NUM> reaches high speed, the hull <NUM> eventually shifts from a hump state to a planing state. Namely, as the vessel speed V obtained by the hull speed sensor <NUM> increases from zero, the pitch angle P of the hull <NUM> increases, and then the pitch angle P rapidly decreases. After that, when the vessel speed V further increases and the pitch angle P becomes substantially equal to zero, the planing state of the hull <NUM> becomes stable.

A state in which the speed of the hull <NUM> falls within a speed range indicated by diagonal lines in <FIG> corresponds to a state in which the hull <NUM> is in a critical state between a non-planing state and the planing state. In other words, the state in which the speed of the hull <NUM> falls within the speed range indicated by the diagonal lines in <FIG> corresponds to a state in which the hull <NUM> is in a critical state between a hump state and a planing state. The speed range indicated by the diagonal lines is a range from a critical minimum speed V1 and a critical maximum speed V2. Even in the planing state, when the speed of the hull <NUM> enters the critical state, there is a possibility that the hull <NUM> will shift to the non-planing state if the throttle opening angle remains unchanged. It should be noted that in the strict sense, the range where the speed of the hull <NUM> is in the critical state varies with loads the hull <NUM> carries and positions of the hull's center of gravity.

A speed V0, which is a predetermined fixed value, is sufficiently higher than zero and lower than a speed at which the hull <NUM> enters the planing state. A maximum pitch angle P1, which is a maximum pitch angle in the critical state, is a fixed value. A minimum pitch angle P2, which is a minimum pitch angle in the critical state, is a fixed value. The critical minimum speed V1 mentioned above is a speed at which the pitch angle P reaches the maximum pitch angle P1 when the vessel speed V is higher than the speed V0. The critical maximum speed V2 is a speed at which the pitch angle P reaches the minimum pitch angle P2 when the vessel speed V is higher than the speed V0. The speed V0, the maximum pitch angle P1, and the minimum pitch angle P2 are stored in the ROM <NUM> in advance.

It should be noted that in the present preferred embodiment, it is not absolutely necessary to recognize the critical minimum speed V1. A set speed THV is a speed set at a higher value than the critical maximum speed V2. In the present preferred embodiment, it is not necessary to use the set speed THV. It should be noted that a speed Vz is an example of the vessel speed in the planing state at not-low speed.

When maneuvered in shallows or the like, the hull <NUM> is required to plane as slowly as possible. However, it is difficult to manually adjust the throttle opening angle so as to keep the planing state at low speed. Thus, as described below with reference to <FIG>, by using the critical maximum speed V2 substantially as a target value of the vessel speed V, the CPU <NUM> controls the opening angle adjustment unit <NUM> so as to keep the planing state.

<FIG> is a flowchart of a throttle control process. This process is implemented by the CPU <NUM> expanding a control program stored in the ROM <NUM> into the RAM <NUM> and executing the same. This process is started when, for example, the maneuvering system is activated. In this process, the CPU <NUM> acts as a control unit of the present invention.

First, in step S101, the CPU <NUM> carries out a setting process. In the setting process, settings are made based on matters input through the setting operation unit <NUM>. For example, when a user issues an instruction to set the planing mode, in which the planing state is maintained, by operating the setting operation unit <NUM>, the CPU <NUM> sets the planing mode. In step S102, the CPU <NUM> determines whether or not the planing mode is set. When the planing mode is not set, the process proceeds to step S104, in which the CPU <NUM> performs normal control. In the normal control, the CPU <NUM> controls the opening angle adjustment unit <NUM> based on the operational position of the throttle lever <NUM> (throttle operator). Then, in step S105, the CPU <NUM> carries out other processes, followed by the process returning to the step S101. Here, "other processes" mean various types of processes which are carried out according to, for example, settings made and operations performed with the setting operation unit <NUM>. For example, when an instruction to cancel the planing mode is issued using the setting operation unit <NUM>, the planing mode is canceled. Also, when an instruction to stop the maneuvering system is issued, a process that ends this flowchart is carried out.

As a result of the determination in the step S102, when the planing mode is set, the CPU <NUM> determines whether or not the hull <NUM> has entered the planing state. Here, whether or not the hull <NUM> has entered the planing state is determined according to whether or not the pitch angle P is equal to or smaller than the minimum pitch angle P2 (P ≤ P2) in a state where the vessel speed V is higher than the speed V0 (V0 < V). When the pitch angle P is equal to or smaller than the minimum pitch angle P2 (P ≤ P2) in a state where the vessel speed V is higher than the speed V0 (V0 < V), it is determined that the hull <NUM> has entered the planing state. As described above, the pitch angle P is obtained based on a signal output from the posture sensor <NUM>.

When the CPU <NUM> determines in the step S103 that the hull <NUM> has not entered the planing state, the process proceeds to the step S104. On the other hand, the hull <NUM> has entered the planing state, the CPU <NUM> starts decelerating the hull <NUM> in step S106. Namely, the CPU <NUM> controls the opening angle adjustment unit <NUM> so as to reduce the throttle opening angle of the engine <NUM> by a predetermined amount irrespective of the operational position of the throttle lever <NUM>.

In step S107, the CPU <NUM> determines whether or not the planing mode is applied, and when the planing mode is not applied, the process proceeds to the step S104. It should be noted that in step S110, which will be described later, the planing mode may be canceled. On the other hand, when the planing mode is applied, the process proceeds to step S108, in which the CPU <NUM> determines whether or not the hull <NUM> is in the critical state between the planing state and the non-planing state. Namely, the CPU <NUM> determines whether or not the hull <NUM> has shifted from the planing state to the critical state. Here, whether or not the hull <NUM> is in the critical state is determined based on the vessel speed V and the pitch angle P. Specifically, when the pitch angle P is greater than the minimum pitch angle P2 and equal to or smaller than the maximum pitch angle P1 (P2 < P ≤ P1) in a state where the vessel speed V is higher than the speed V0 (V0 < V), it is determined that the hull <NUM> is in the critical state.

As a result of the determination in the step S108, when the hull <NUM> is in the critical state, there is a possibility that if nothing is done, the hull <NUM> will shift to the non-planing state. To avoid that situation, in step S109, the CPU <NUM> controls the opening angle adjustment unit <NUM> so as to increase the throttle opening angle of the engine <NUM> by a predetermined amount irrespective of the operational position of the throttle lever <NUM>. This brings the hull <NUM> back from the critical state to the low-speed planing state. The CPU <NUM> proceeds then the process to the step S110.

As a result of the determination in the step S108, when the hull <NUM> is not in the critical state, the process proceeds to step S111, in which the CPU <NUM> determines whether or not the hull <NUM> is in the planing state. As a result of the determination in the step S111, when the hull <NUM> is in the planing state, the process proceeds to step S112, in which the CPU <NUM> controls the opening angle adjustment unit <NUM> so as to reduce the throttle opening angle of the engine <NUM> by a predetermined amount irrespective of the operational position of the throttle lever <NUM>. As a result, while the planing state is continuing after the start of deceleration, the throttle opening angle gradually decreases, causing the vessel speed V to decrease. Also when the hull <NUM> has shifted from the critical state to the planing state, the CPU <NUM> reduces the throttle opening angle of the engine <NUM> by only the predetermined amount. This prevents the speed of the hull <NUM> from becoming too high. Thus, the planing state at relatively low speed is maintained. After that, the CPU <NUM> proceeds the process to the step S110.

As described above, by repeating the steps S109 and S112, the throttle angle is adjusted by using the critical maximum speed V2 substantially as a target speed of the hull <NUM>.

On the other hand, when the CPU <NUM> determines in the step S111 that the hull <NUM> is not in the planing state, the CPU <NUM> proceeds the process to the step S104. Namely, in this case, the hull <NUM> has entered the non-planing state, and hence control performed by the CPU <NUM> temporarily returns to the normal control. In the step S110, the CPU <NUM> carries out other processes as with the step S105, followed by the process returning to the step S107.

It should be noted that even in a case where the planing mode is set in a state where the hull <NUM> has entered the planing state, the opening angle adjustment unit <NUM> is controlled in step S112 so as to reduce the throttle opening angle of the engine <NUM> by the predetermined amount. Thus, by adopting an appropriately small value as this predetermined amount, the hull <NUM> can be gradually decelerated. It should be noted that the predetermined amounts used in the respective steps S106, S109, and S112 should not necessarily be the same.

According to the present preferred embodiment, when it is judged that the planing mode is set and the hull <NUM> has entered the planing state, the hull <NUM> is decelerated. Then, the opening angle adjustment unit <NUM> is controlled to keep the hull <NUM> in the planing state even when the hull <NUM> has been decelerated. Specifically, when it is judged that the hull <NUM> has shifted from the planing state to the critical state while the planing mode is applied, the opening angle adjustment unit <NUM> is controlled so as to increase the throttle opening angle. Also, when it is judged that the hull <NUM> has shifted from the critical state to the planing state, the opening angle adjustment unit <NUM> is controlled so as to decrease the throttle opening angle. As a result, the vessel speed V is controlled by using the critical maximum speed V2 substantially as a target value, and hence the planing state at relatively low speed can be maintained.

A description will now be given of another preferred embodiment of the present invention. The present preferred embodiment differs from the preferred embodiment firstly described above in its throttle control process, and they are identical in the other features.

<FIG> is a flowchart of a throttle control process according to the present preferred embodiment. This throttle control process is carried out on the same condition and by the same component as the one described with reference to <FIG>. In steps S201 to <NUM>, the CPU <NUM> carries out the same processes as those in the steps S101 to S105 in <FIG>.

As a result of the determination in the step S203, when the hull <NUM> has entered the planing state, the process proceeds to step S206, in which the CPU <NUM> obtains the vessel speed V at the time when the hull <NUM> shifts from a state other than the planing state to the planing state, and then the CPU <NUM> stores the obtained vessel speed V in the RAM <NUM>, which is an example of a storage unit. Then, in step S207, the CPU <NUM> sets a value based on the vessel speed V stored in the RAM <NUM> as the set speed THV. The stored vessel speed V is estimated to be a value close to the critical maximum speed V2, and hence the CPU <NUM> sets, for example, a value greater by a margin than the critical maximum speed V2 as the set speed THV.

It should be noted that in the step S206, when the planing mode is set in the state where the hull <NUM> is not in the planing state, the above-mentioned vessel speed V can be obtained. Namely, in a case where the process proceeds from the step S203 to the step S206 after proceeding from the step S203 to the step S204, the CPU <NUM> can obtain the above-mentioned vessel speed V. However, in a case where the planing mode is set after the hull <NUM> enters the planing state, the CPU <NUM> cannot obtain the above-mentioned vessel speed V. In this case, the CPU <NUM> sets a fixed value as the set speed THV in step S207. This fixed value is stored in the ROM <NUM> in advance. This fixed speed is a value obtained by, for example, adding a margin to a "value corresponding to the critical maximum speed V2", which is experimentally known in advance. As described above, since the critical maximum speed V2 varies with loads the hull <NUM> carries, it is preferred that the "value corresponding to the critical maximum speed V2" is a value obtained under average conditions. It should be noted that in the step S207, the fixed value may always be set as the set speed THV irrespective of the vessel speed V.

In step S208, the CPU <NUM> carries out the same process as in the step S106 in <FIG>. In steps S209 to S214, a range from the critical maximum speed V2 to the set speed THV is set as a target range, and the throttle opening angle is adjusted so that the vessel speed V can fall within this target range. Namely, the set speed THV corresponds to an upper limit to a target range of the vessel speed V, which is targeted so as to maintain the planing state at low speed. First, in the steps S209 to S212, the CPU <NUM> carries out the same processes as those in the steps S107 to S110 in <FIG>. When the CPU <NUM> determines in the step S209 that the planing mode is not applied, the process proceeds to the step S204. When the CPU <NUM> determines in the step S210 that the hull <NUM> is not in the critical state, the process proceeds to the step S213.

In the step S213, the CPU <NUM> obtains the present vessel speed V and determines whether or not the present vessel speed V is higher than the set speed THV (V > THV). In a state where the present vessel speed V is not higher than the set speed THV, the vessel speed V falls within the target range and the planing state at low speed is maintained, and thus the CPU <NUM> proceeds the process to the step S212. In a state where the present vessel speed V is higher than the set speed THV, the vessel speed V falls beyond the target range, and hence the process proceeds to the step S214, in which the CPU <NUM> carries out the same process as the one in the step S112 in <FIG>. The process then proceeds to the step S212. It should be noted that in the step S212, a process in which the process returns to the step S204 when the hull <NUM> has entered the non-planing state is carried out in addition to the same process as the one in the step S110.

According to the present preferred embodiment, as with the preferred embodiment firstly described above, when it is judged that the hull <NUM> has shifted from the planing state to the critical state while the planing mode is applied, the opening angle adjustment unit <NUM> is controlled so as to increase the throttle opening angle. Also, in the present preferred embodiment, when the present vessel speed V becomes higher than the set speed THV, the opening angle adjustment unit <NUM> is controlled so as to decrease the throttle opening angle. As a result, the vessel speed V is controlled to substantially fall within the target range between the critical maximum speed V2 and the set speed THV. Therefore, the same effects as those in the preferred embodiment firstly described above can be obtained from the standpoint of maintaining the planing state at relatively low speed.

It should be noted that as described above, the vessel speed V stored when the hull <NUM> has shifted into the planing state is a value close to the critical maximum speed V2. Here, the throttle opening angle may be adjusted by setting the stored vessel speed V as the target speed of the hull <NUM>. Alternatively, in the preferred embodiment firstly described above, the throttle opening angle may be adjusted by setting the "value corresponding to the critical maximum speed V2", which is experimentally known in advance, as the target speed for the hull <NUM>. In such cases, control can be performed in substantially the same manner as in the control performed in the preferred embodiment firstly described above.

A description will now be given of further another preferred embodiment of the present invention. The present preferred embodiment differs from the preferred embodiment secondly described above in that the set speed THV is varied according to the turning state of the hull and is identical with the preferred embodiment secondly described above in the other features.

<FIG> is a flowchart of a throttle control process according to the present preferred embodiment. Processes in steps S301 to S303 are carried out immediately after the step S212 (the other processes) in <FIG>. It should be noted that the processes in steps S301 to S303 may be carried out either immediately before the step S212 or as a part of the step S212.

First, in the step S301, based on a signal output from the posture sensor <NUM>, the CPU <NUM> determines whether or not the hull <NUM> is turning. When the hull <NUM> is turning, the process proceeds to the step S302, in which the CPU <NUM> sets a new set speed THV (i.e. updates the set speed THV) by adding a predetermined amount to the present set speed THV (i.e. upping the present set speed THV). The CPU <NUM> then returns the process to the step S209. The reasons to increase the set speed THV will be described below.

One reason is that while the hull <NUM> is turning, there is a possibility that the pitch angle P and the vessel speed V cannot be accurately detected. Another reason is that when the vessel speed V is obtained using a GPS, there is a high possibility that the vessel speed V smaller (slower) than it actually is will be obtained. Therefore, increasing the set speed THV can avoid a state where the hull <NUM> is likely to shift from the planing state to the critical state.

As a result of the determination in the step S301, when the hull <NUM> is not turning, the process proceeds to step S303, in which the CPU <NUM> resets the set speed THV to the original value (that was set in the step S207). It should be noted that when the set speed THV has not been updated, this set speed THV is maintained. Then, the CPU <NUM> return the process to the step S209.

According to the present preferred embodiment, the same effects as those in the preferred embodiment secondly described above can be obtained from the standpoint of maintaining the planing speed at relatively low speed. Moreover, during the time that it is detected that the hull <NUM> is turning, the set speed THV is set to a larger value as compared to the time that it is not detected that the hull <NUM> is turning, and hence the planing state can be maintained at relatively low speed even while the hull <NUM> is turning.

It should be noted that the predetermined value added in the step S302 may be a fixed value. Alternatively, the amount of turn may be detected, and a value corresponding to the detected amount of turn may be added to the set speed THV in place of the predetermined value. In this case, the set speed THV appropriate to the state of turn can be set, and therefore, the planing state at low speed can be maintained irrespective of the extent to which the hull <NUM> turns.

A description will now be given of further another preferred embodiment of the present invention. As compared to the preferred embodiment firstly described above, the present preferred embodiment focuses on a case where the throttle lever <NUM> is operated while the opening angle adjustment unit <NUM> is being controlled so as to keep the hull <NUM> in the planing state.

<FIG> is a flowchart of a throttle control process according to the present preferred embodiment. Processes in steps S401 to S407 are carried out immediately after the step S110 (the other processes) in <FIG>. It should be noted that the processes in steps S401 to S407 may be carried out either immediately before the step S110 or as a part of the step S110.

In the step S401, the CPU <NUM> determines whether or not an operational position of the throttle lever <NUM> lies in an opening direction as compared to an operational position corresponding to a throttle opening angle under control (the present throttle opening angle). It should be noted that as described above, while the planing mode is applied, the operational position of the throttle lever <NUM> does not always correspond to an actual throttle opening angle. When the CPU <NUM> determines that the operational position of the throttle lever <NUM> lies in an opening direction as compared to the operational position corresponding to the throttle opening angle being controlled, the process proceeds to step S402, and when not, the process proceeds to the step S107. In the step S402, the CPU <NUM> determines whether or not the throttle lever <NUM> has been further operated in the opening direction as compared to the operational position corresponding to the throttle opening angle under control. When the CPU <NUM> determines that the throttle lever <NUM> has been further operated in the opening direction as compared to the operational position corresponding to the throttle opening angle under control, the process proceeds to step S403, and when not, the process proceeds to step S405.

In the step S403, it is judged that a vessel operator has an intention of shifting to a mode of a manual operation and starting acceleration, and therefore, the CPU <NUM> cancels the planing mode. Then, in step S404, the CPU <NUM> controls the opening angle adjustment unit <NUM> so that the throttle opening angle can gradually shift to the throttle opening angle corresponding to the operational position of the throttle lever <NUM> operated this time. The throttle opening angle under control is an opening angle corresponding to the critical maximum speed V2 or its vicinity, whereas the throttle opening angle corresponding to the operational position of the throttle lever <NUM> immediately after being operated in the opening direction can be sufficiently higher than the opening angle corresponding to the critical maximum speed V2 or its vicinity. In this case, if the throttle opening angle is immediately shifted to the one corresponding to the operational position of the throttle lever <NUM> after the operation this time, the hull <NUM> may be unintentionally rapidly accelerated. Thus, the speed of the hull <NUM> can be slowly changed by the throttle opening angle being gradually shifted to the throttle opening angle corresponding to the operational position of the throttle lever <NUM> after the operation. The gap between the operational position of the throttle lever <NUM> and the actual throttle opening angle is gradually eliminated.

In the step S405, the CPU <NUM> determines whether or not the throttle lever <NUM> has been operated in a closing direction past the (present) throttle opening angle under control. Namely, the CPU <NUM> determines whether or not the throttle lever <NUM> has been operated in the closing direction and also the operational position of the throttle lever <NUM> after the operation is lower than the operational position corresponding to the throttle opening angle under control. When the CPU <NUM> determines that the throttle lever <NUM> has been operated in the closing direction past the (present) throttle opening angle under control, the process proceeds to step S406, and when not, the process proceeds to the step S107.

In the step S406, it is judged that the vessel operator has an intention of shifting to the mode of manual operation and starting deceleration, the CPU <NUM> cancels the planing mode. Thus, after the operational position of the throttle lever <NUM> has become lower than the operational position corresponding to the throttle opening angle under control, the planing mode is canceled. Namely, the planing mode is not canceled in a stage where the throttle lever <NUM> has been operated in a closing direction within a range where its operational position does not become lower than the operational position corresponding to the throttle opening angle under control.

Then, in step S407, the CPU <NUM> controls the opening angle adjustment unit <NUM> so that the throttle opening angle can gradually shift to the throttle opening angle corresponding to the operational position of the throttle lever <NUM> after the operation this time. The throttle opening angle under control is an opening angle corresponding to the critical maximum speed V2 or its vicinity, whereas the throttle opening angle corresponding to the operational position of the throttle lever <NUM> immediately after being operated slightly in the closing direction is likely to be sufficiently higher than the opening angle corresponding to the critical maximum speed V2 or its vicinity. In this case, if the throttle opening angle is immediately shifted to the throttle opening angle corresponding to the operational position of the throttle lever <NUM> after the operation this time, the hull <NUM> may be likely to accelerate even though the vessel operator has an intention of decelerating the hull <NUM>. Thus, after the operational position of the throttle lever <NUM> has become lower the operational position corresponding to the throttle opening angle under control, the planing mode is canceled and the throttle opening angle is gradually shifted to the throttle opening angle corresponding to the operational position of the throttle lever <NUM> after the operation, and whereby the speed the hull <NUM> can change slowly. The gap between the operational position of the throttle lever <NUM> and the actual throttle opening angle is gradually eliminated. After the step S404 or the step S407, the CPU <NUM> returns the process to the step S104 in <FIG>.

According to the present preferred embodiment, the same effects as those in the preferred embodiment firstly described above can be obtained from the standpoint of maintaining the planing state at relatively low speed. Moreover, in a situation where the operational position of the throttle lever <NUM> lies in the opening direction as compared to the operational position corresponding to the throttle opening angle under control while the planing state at low speed is being maintained, when the throttle lever <NUM> is further operated in the opening direction, the CPU <NUM> cancels the planing mode and gradually shifts the throttle opening angle to the throttle opening angle corresponding to the operational position of the throttle lever <NUM> after the operation. This prevents unintended rapid acceleration. Also, in the above situation, when the throttle lever <NUM> is operated in the closing direction, after the operational position of the throttle lever <NUM> has become lower the operational position corresponding to the throttle opening angle under control, the CPU <NUM> cancels the planing mode and gradually shifts the throttle opening angle to the throttle opening angle corresponding to the operational position of the throttle lever <NUM> after the operation. As a result, a situation in which the hull <NUM> accelerates even though the throttle lever <NUM> has been operated in the closing direction can be avoided.

Appropriately lowering the tabs <NUM> of the trim tabs <NUM> can make it easier to maintain the planing state at low speed. For this purpose, in the preferred embodiments described above, while the planing mode is applied, two tabs <NUM> may be controlled to be lowered by a predetermined amount.

For example, when the planing mode is set, the tabs <NUM> may be lowered even if the hull <NUM> has not entered planing state. In this case, referring to <FIG>, for example, it may be considered to insert a step of lowering the tabs <NUM> between the step S102 and the step S103 and insert a step of raising the tabs <NUM> (putting them back to retracted positions) between a timing of the determination as NO in the step S107 and a timing of a return to the step S104. Referring to <FIG>, it may be considered to insert a step of lowering the tabs <NUM> between the step S202 and the step S203 and insert a step of raising the tabs <NUM> between a timing of the determination as NO in the step S209 and a timing of a return to the step S204.

Alternatively, the tabs <NUM> may be lowered when both the condition that the planing mode is set and the condition that the hull <NUM> is in the planing state are satisfied. In this case, referring to <FIG>, for example, a step of lowering the tabs <NUM> is inserted after the determination as YES in the step S103 and before the step S107. At the same time, a step of raising the tabs <NUM> (putting them back to the retracted positions) may be inserted after the determination as NO in the step S107 and before a return to the step S104. Referring to <FIG>, a step of lowering the tabs <NUM> is inserted after the determination as YES in the step S203 and before the step S209. At the same time, a step of raising the tabs <NUM> may be inserted after the determination as NO in the step S209 and before the return to the step S204.

It should be noted that in the preferred embodiments described above, whether or not the hull <NUM> is in the critical state is judged based on the vessel speed V and the pitch angle P in the steps S108 and S210. The method of judgment, however, is not limited to this example. For example, whether or not the hull <NUM> is in the critical state may be judged based on the vessel speed V and the engine rpm N. Alternatively, whether or not the hull <NUM> is in the critical state may be judged based on the vessel speed V and the throttle opening angle.

It should be noted that in a case where an operation that lowers the tabs <NUM> of the trim tabs <NUM> is performed in parallel with the control that maintains the planing state at low speed in the planing mode, the predetermined amounts used in the steps S106, S109, S112, S208, S211, and S214 may be set according to the amount by which the tabs <NUM> is lowered and/or the load the hull <NUM> carries.

It should be noted that interceptor tabs may be adopted as posture control members in place of the tabs <NUM>. In the water, each of the interceptor tabs changes its position from a position at which it projects from a bottom surface (vessel's bottom) of the hull <NUM> to a retracted position above the bottom surface of the hull <NUM>.

Claim 1:
A control system for a marine vessel (<NUM>), comprising:
an opening angle adjustment unit (<NUM>) configured to adjust a throttle opening angle of an engine in a propulsion device (<NUM>); and
a controller (<NUM>) configured to
judge whether or not a hull (<NUM>) has entered a planing state, and
set a predetermined mode in which the planing state is maintained,
characterized in that
the controller (<NUM>) is further configured to
judge whether or not the hull (<NUM>) is in a critical state between the planing state and a non-planing state based on a speed of the hull (<NUM>) and a pitch angle of the hull (<NUM>), and
in a case where the predetermined mode is set and it is judged that the hull (<NUM>) has entered the planing state and then judged that the hull (<NUM>) has shifted from the planing state to the critical state, control the opening angle adjustment unit (<NUM>) so as to increase the throttle opening angle and keep the hull (<NUM>) in the planing state.