Control apparatus for an outboard marine engine with improved cruising performance

A control apparatus for an outboard marine engine is able to improve cruising performance of a boat particularly during acceleration or travelling on a curved course. An attitude angle sensor senses a three-dimensional attitude of the outboard engine including a trim angle, a bank angle and a yaw or steering angle thereof, and generates corresponding attitude angle signals. A controller controls engine control parameters based on various signals indicative of engine operating conditions inclusive of the attitude angle signals in such a manner that the output power of the engine increases in accordance with an increasing trim angle, whereas it decreases in accordance with an increasing bank and/or yaw (steering) angle.

BACKGROUND OF THE INVENTION 
The present invention relates to a control apparatus for controlling the 
operation of an outboard marine engine. More particularly, it relates to 
an engine control apparatus which is able to adjust or modify engine 
control parameters in response to a three-dimensional attitude of an 
outboard engine, which is mounted on a boat, to prevent the boat from 
deviating from a predetermined cruising course for improved cruising 
performance. 
FIG. 6 schematically illustrates a typical example of an outboard marine 
engine mounted on a boat. In this figure, the engine 1 in the form of an 
internal combustion engine for outboard use is disposed outside a boat 
hull 3 at the stern thereof and pivotally mounted to the boat hull 3 
through a mounting bracket 1a so that it is pivotable around a vertical 
pivot axis (Z-axis) as well as an athwart pivot axis P1 (Y-axis) which 
extends horizontally athwart of the boat hull 3. Upon acceleration of the 
engine 1, it is caused under an acceleration force to pivot or incline 
around the athwart pivot axis P1 (Y-axis) at an attitude angle or angle of 
tilt .THETA..sub.1 (i.e., so-called "trim angle") from a normal or 
vertical position (i.e., a reference or vertical line) which the engine 1 
takes in a steady-state operation. The engine 1 is steered to turn around 
the vertical pivot axis (Z-axis) by an operator through an unillustrated 
steering and throttle arm lever. A propulsion screw 2 is disposed under 
water and operatively connected with the engine 1 so that it is thereby 
driven to rotate, generating a propulsion force. 
FIG. 7 shows in block form the general construction of a conventional 
engine control apparatus for controlling the outboard engine 1 of FIG. 6. 
In this figure, a rotational speed sensor 4 mounted on a camshaft or 
crankshaft (not illustrated) of the engine 1 generates a crank angle 
signal R representative of a reference crankshaft position in 
synchronization with the rotation of the unillustrated crankshaft for 
sensing the rotational speed or the number of revolutions per minutes of 
the engine 1. A gear position sensor 5 senses the gear position of a 
transmission (not shown) of the engine 1 and generates a corresponding 
gear position signal G. A controller 6 receives output signals from 
various sensors indicative of various engine operating conditions such as 
the degree of throttle opening, the intake pressure in an intake manifold, 
etc., including the output signals R, G from the rotational speed sensor 4 
and the gear position sensor 5, and generates a drive signal A for 
controlling various engine control parameters on the basis of these output 
signals. An actuator means 7 is operatively connected to receive the drive 
signal A from the controller 6 so that it is driven to operate by the 
controller 6 through the drive signal A. The actuator means 7 controls 
various driving and control elements or devices such as a fuel pump, an 
ignition coil, a throttle valve, a starter motor and the like associated 
with the engine 1. 
Next, the operation of the above-described conventional engine control 
apparatus will be described in detail while referring to FIGS. 6 and 7. 
First, the controller 6 generates a drive signal A based on the output 
signals from the various sensors including the rotational speed signal R, 
the gear position signal G, the reference crank signal and the like 
representative of various engine operating conditions, for controlling the 
actuator means 7 (e.g., for controlling a fuel pump, an ignition coil, a 
throttle valve, etc.) as well as calculating and controlling operational 
timings thereof such as fuel supply or injection timing, ignition timing, 
etc. As a result of such calculations, the controller 6 generates an 
appropriate drive signal A so that the actuator 7 is thereby operated to 
properly control engine control parameters such as the flow rate of intake 
air sucked into the engine 1, the amount of fuel supplied to the engine 1, 
the ignition timing and the like, thus providing a desired number of 
revolutions per minute of the engine 1. 
In this connection, since the engine load varies in accordance with a 
change in the three-dimensional attitude of the engine 1, control 
performed by the actuator means 7 on the engine control parameters through 
the drive signal A, which is calculated and generated by the controller 6 
on the basis of various sensor signals without taking account of the 
engine load, becomes improper or unsuitable, so the boat often deviates 
from an intended cruising course such as during acceleration or turning 
motion thereof, thus reducing or impairing the cruising performance. In 
particular, in case of acceleration on a curved course, not only the trim 
angle .theta..sub.1 but also other angles of inclination (bank and yaw 
angles) of the boat hull 3 with respect to three reference axes (i.e., the 
vertical Z-axis, the longitudinal X-axis extending longitudinally of the 
boat hull 3 and perpendicularly to the vertical Z-axis, and the athwart 
Y-axis extending athwart of the boat hull 3 and perpendicularly to the 
vertical Z-axis and the longitudinal X-axis) become greater, resulting in 
a greater deviation in the cruising course of the boat. Thus, the cruising 
performance of the boat is varied in accordance with the three-dimensional 
attitude of the outboard engine 1, so it is difficult for the conventional 
engine control apparatus to provide for intended good cruising performance 
desired by the operator at all times. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention is aimed at overcoming the 
above-described problems encountered with the conventional marine engine 
control apparatus. 
An object of the invention is to provide a novel and improved control 
apparatus for an outboard marine engine which is able to improve cruising 
performance of a boat during acceleration as well as turning movements 
thereof. 
In order to achieve the above object, according to the present invention, 
there is provided a control apparatus for an outboard marine engine which 
is mounted on the hull of a boat for pivotal movements around an athwart 
pivot axis and a vertical pivot axis, the apparatus comprising: sensor 
means for sensing various operating conditions of the engine and 
generating corresponding output signals; an attitude angle sensor for 
sensing a three-dimensional attitude of the engine and generating 
corresponding attitude angle signals; a controller operatively connected 
to receive the output signals from the sensor means and the attitude angle 
sensor so that it generates a basic drive signal for controlling operating 
parameters of the engine based on the output signals from the sensor 
means, the controller including modification means for modifying the basic 
drive signal based on the attitude angle signals from the attitude angle 
sensor for optimal engine control; and actuator means operatively 
connected to receive the output drive signal from the controller so that 
it is thereby driven to optimally control the operation of the engine. 
The attitude angle sensor senses a trim angle, a bank angle and a yaw angle 
of the outboard engine. The trim angle is defined as a tilt angle of the 
engine with respect to a vertical line around the athwart pivot axis. The 
bank angle is defined as an angle of side inclination of the engine with 
respect to a vertical line. The yaw angle is defined as a steering angle 
of the engine with respect to a longitudinal center line of the boat hull 
around a vertical line. 
The controller modifies the basic drive signal such as to increase the 
output power of the engine in accordance with the increasing trim angle. 
This serves to increase the engine output power so as to meet an 
increasing engine load during acceleration of the boat. 
The controller also modifies the basic drive signal in such a manner that 
the output power of the engine decreases in accordance with the increasing 
bank or yaw angle. 
The above and other objects, features and advantages of the invention will 
become apparent from the ensuing detailed description of the invention 
taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A preferred embodiment of the invention will now be described in detail 
with reference to the accompanying drawings. 
FIG. 1 shows in block form an engine control apparatus for controlling the 
operation of an outboard marine engine constructed in accordance with the 
principles of the present invention. In this figure, the apparatus 
illustrated includes, in addition to a rotational speed sensor 40, a gear 
position sensor 50 and an actuator means 70 all of which are similar to 
the corresponding elements 4, 5 and 7, respectively, of FIG. 7, an 
attitude angle sensor 80 for sensing the three-dimensional attitude of an 
outboard marine engine 1 (see FIG. 6) and generating corresponding 
attitude angle signals .THETA..sub.1, .THETA..sub.2, .THETA..sub.3, and a 
controller 60 for controlling the actuator means 70 on the basis of the 
output signals from the sensors 40, 50 and 80 as well as other signals 
from unillustrated sensors representative of various engine operating 
conditions. 
The controller 60 comprises an input interface 61 to which various signals 
inclusive of a rotational speed signal R from the rotational speed sensor 
40, a gear position signal G from the gear position sensor 50 and attitude 
signals .THETA..sub.1, .THETA..sub.2, .THETA..sub.3 from the attitude 
sensor 80 as well as other signals representative of various engine 
operating conditions are input, a microcomputer 62 for effecting various 
computations and making determinations on the basis of various input 
signals supplied to the input interface 61 and generating a drive signal 
A' for controlling and driving the actuator means 70, and an output 
interface 63 for outputting the drive signal A' generated by the 
microcomputer 62 to the actuator means 70. 
The attitude angle sensor 80 comprises, for example, a vector-type angular 
velocity sensor such as a gas rate sensor which senses the 
three-dimensional attitude of the outboard marine engine 1, i.e., a trim 
angle .THETA..sub.1, a bank angle .THETA..sub.2 and a yaw or steering 
angle .THETA..sub.3 of a boat on which the engine control apparatus of the 
invention is mounted, and generates corresponding attitude angle signals 
comprising a trim-angle signal, a bank-angle signal and a yaw-angle signal 
to the input interface 61 of the controller 60. Specifically, the trim 
angle .THETA..sub.1 is defined as an angle of tilt of the engine 1 with 
respect to a vertical reference line P2 (Z-axis) about a first or athwart 
pivot axis P1 (Y-axis) which extends horizontally athwart of the boat hull 
3, as clearly shown in FIG. 2. The bank angle .THETA..sub.2 is defined as 
an angle of side inclination of the engine 1 or the boat hull 3 with 
respect to the vertical reference line P2 (Z-axis) around a second or 
longitudinal pivot axis P3 (X-axis) which extends horizontally and 
longitudinally of the boat hull 3, as clearly shown in FIG. 3. The yaw 
angle .THETA..sub.3 is defined as an angle of steering of the engine 1 
around a vertical pivot axis or the vertical reference line P2 (Z-axis), 
as clearly shown in FIG. 4. The trim angle .THETA..sub.1 and the yaw angle 
.THETA..sub.3 are varied by a steering operation of an operator, whereas 
the bank angle .THETA..sub.2 may vary irrespective of the operator's will 
or steering operation. In addition, instead of using the vector-type 
angular velocity sensor, the trim angle .THETA..sub.1 and the yaw or 
steering angle .THETA..sub.3 can be directly sensed by measuring 
rotational or steering angles of the engine 1 around the athwart and 
vertical pivot axes P1, P2, respectively, caused by the operator. 
The microcomputer 62 in the controller 60 computes control quantities for 
engine control parameters based on various engine operating conditions 
which are sensed by and input thereto from various sensors via the input 
interface 61, and generates a corresponding basic drive signal A for 
driving and controlling the actuator means 70, as described with reference 
to the conventional engine control apparatus of FIG. 7. 
The microcomputer 62 includes a correcting or modifying means for 
correcting or modifying the thus computed basic control quantities for 
engine control parameters in dependence upon the attitude angle signals 
indicative of the trim angle .THETA..sub.1, the bank angle .THETA..sub.2 
and the yaw or steering angle .THETA..sub.3 supplied from the attitude 
angle sensor 80 to the input interface 61 of the controller 60, as will be 
described later in detail. 
Next, the operation of the above embodiment will be described in detail 
while referring to the flow chart of FIG. 5 as well as FIGS. 2 through 4 
and FIG. 6. As shown in FIG. 5, first in Step S1, the microcomputer 62 
computes the rotational speed or the number of revolutions per minute of 
the engine 1 based on the output signal R from the rotational speed sensor 
40, and it determines the current gear position of an unillustrated 
transmission of the engine 1 based on the gear position signal G from the 
gear position sensor 50. On the basis of the rotational speed and the 
current gear position of the engine 1 as well as other engine operating 
conditions as sensed by unillustrated various sensors, the microcomputer 
62 computers optimal control quantities for engine control parameters such 
as a degree of opening of a throttle valve, an amount of fuel to be 
supplied to the engine 1, the ignition timing, etc., and generates a 
corresponding basic drive signal A for controlling and driving the 
actuator means 70 to this end. 
In Step S2, the attitude angle signals indicative of the trim angle 
.THETA..sub.1, the bank angle .THETA..sub.2 and the yaw or steering angle 
.THETA..sub.3 of the engine 1, as sensed by the attitude angle sensor 80, 
are input therefrom to the microcomputer 62 via the input interface 61. 
In Step S3, on the basis of these attitude angle signals, the microcomputer 
62 computes a correction or modification quantity .DELTA.A for correcting 
or modifying the basic engine control parameters as follows. 
EQU .DELTA.A=f(.THETA..sub.1, .THETA..sub.2, .THETA..sub.3) 
Then in Step S4, based on the correction or modification quantity .DELTA.A 
thus computed, the microcomputer 62 modifies the basic drive signal A in 
the following manner to provide a corrected or modified drive signal A' 
which is supplied via the output interface 63 to the actuator means 70. 
EQU A'=A+.DELTA.A 
In this manner, the actuator means 70 is properly controlled or driven by 
the modified drive signal A' from the microcomputer 62 to thereby control 
the engine control parameters in an optimal manner. Specifically, for 
example, if the trim angle .THETA..sub.1 of the engine 1 increases such as 
during rapid acceleration of the engine 1 and hence of the boat hull 3, 
the correction or modification quantity .DELTA.A is increased to augment 
the output power of the engine 1 so as to meet the increasing engine load. 
On the other hand, however, if the bank angle .THETA..sub.2 or the 
steering angle .THETA..sub.3 is increased such as when the boat is steered 
to turn around a curved course, the correction or modification quantity 
.DELTA.A is decreased to reduce the engine output power so as to prevent 
overturn of the boat due to an otherwise increasing centrifugal force 
acting thereon. 
Moreover, the control of increasing or decreasing the engine output power 
can be made by means of the drive signal A' supplied to the actuator means 
70 in a variety of ways. For example, on the basis of the drive signal A', 
the actuator 70 adjusts to increase or decrease the amount of fuel 
supplied from an unillustrated fuel pump to the engine 1, or it adjusts to 
properly advance or delay the ignition timing of the engine 1, or it 
increases or decreases the throttle opening (i.e., the degree of opening 
of an unillustrated throttle valve). 
In this manner, the original or basic drive signal A is modified on the 
basis of the attitude angles .THETA..sub.1, .THETA..sub.2, .THETA..sub.3 
of the engine 1 to provide the modified drive signal A' whereby the 
operation of the actuator means 70 can be properly corrected or modified 
to allow the engine 1 to exhibit its maximum cruising performance other 
than during turning motion of the boat, thus ensuring excellent 
acceleration performance of the boat in exact response to the operator' 
will or steering operation while avoiding overturn of the boat during 
turning motion along a curved course.