Information
-
Patent Grant
-
6520167
-
Patent Number
6,520,167
-
Date Filed
Monday, July 31, 200024 years ago
-
Date Issued
Tuesday, February 18, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Knobbe, Martens, Olson & Bear, LLP
-
CPC
-
US Classifications
Field of Search
US
- 123 674
- 123 679
- 123 687
- 123 478
- 123 479
- 123 480
- 701 102
- 701 103
- 701 105
- 701 110
- 440 1
- 440 89
-
International Classifications
-
Abstract
An engine for a marine vehicle includes a controller having a predetermined map defining a relationship between a fuel injection parameter and an engine operation characteristic. Additionally, the controller includes at least one compensation factor for adjusting the fuel injection parameter. The compensation value is derived from data recorded during a test of the engine. The compensation factor is used during the normal operation of the engine to achieve a predetermined air/fuel ratio.
Description
PRIORITY INFORMATION
This application is based on and claims priority to Japanese Patent Application No. 11-217777, filed Jul. 30, 1999.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an engine for a marine vehicle. More specifically, the present invention relates to an improved feedback control system for the engine of a marine vehicle.
2. Description of Related Art
In all fields of engine design, there is an increasing emphasis on obtaining more effective emission control, better fuel economy and, at the same time, continued high or higher power output. In pursuit of better fuel economy and emission control, various types of control systems have been developed in conjunction with internal combustion engines. One of the more effective types of controls is so-called “feedback” control. With this type of control, a basic air/fuel ratio is set for the engine. Adjustments are then made from the basic setting based on the output of a sensor that senses the air/fuel ratio in the combustion chamber in order to bring the air/fuel ratio into the desired range.
Normally, the type of sensor employed for such feedback control is an oxygen (O
2
) sensor which outputs an electrical signal indicative of the oxygen present in exhaust gases resulting from combustion within the combustion chambers of the engine. Generally, when the output signal voltage is high, little oxygen is present in the exhaust gasses, indicating that a combusted air/fuel charge was rich in fuel. On the other hand, when the output signal voltage is low, substantial amounts of oxygen are present in the exhaust, thus indicating that a combusted charge was rich in air.
A conventional oxygen sensor is normally associated with a wave forming circuit which manipulates the output of the sensor to indicate an “on” signal when the voltage of the output signal exceeds a reference voltage (i.e., a signal which results when the supplied charge is rich in fuel). On the other hand, the circuit manipulates the signal to indicate that the sensor is “off” when the voltage of the output signal does not exceed the reference voltage (i.e., a signal which results from a supplied air/fuel charge which is rich in air).
The control operates on a feedback control principle, continuously making corrections to accommodate deviations from the desired or “target” air/fuel ratio. Adjustments are made in stepped intervals until the sensor output goes to the opposite sense from its previous signal. For example, if the mixture is too rich in fuel (i.e., the sensor signal is “on”), then lean adjustments are made until the mixture strength is sensed to be lean (i.e., the sensor signal turns “off”). Adjustments are then made back into the rich direction in order to approximately maintain the desired ratio.
Most commonly, the oxygen sensor is the type which utilizes inner and outer platinum coated electrodes. Other commonly used oxygen sensors include Yttria (Y
2
O
3
), stabilized Zirconia (Z
r
O
2
) or Titania (T
i
O
2
) electrode sensors. Additionally, Universal Exhaust Gas Oxygen sensors (UEGO sensors) have recently been developed and are based on a heated conventional Zirconia sensor. The UEGO sensors are able to measure a wide range of air/fuel ratios including a very rich mixture (i.e., 10:1) to a very lean mixture (i.e., 35:1).
Such conventional oxygen sensors include an inner electrode exposed to combustion gases of the engine and an outer electrode exposed to atmospheric air. The oxygen sensor uses ambient air as a basis for determining whether oxygen is present in the exhaust gases, as is known in the art.
SUMMARY OF THE INVENTION
One aspect of the present invention includes the realization that known engine sensor assemblies, such as oxygen sensor assemblies, have proven to be inadequate. In particular, it has been found that known combustion condition sensors can have a relatively short useful life span due to the typical operating environments of marine vehicles. For example, as is well known in the art, marine engines typically discharge exhaust gases to the body of water in which the marine vehicle is operating, at a point below the surface of the water, thereby mixing exhaust gases with water upon discharge. Additionally, many 2-stroke engines for marine vehicles are configured to inject water into exhaust gases flowing through the exhaust system immediately downstream of an expansion chamber, to thereby cool the exhaust gases and provide beneficial effects with respect to the tuning of the exhaust system. However, because such exhaust systems can allow saltwater to flow within the exhaust system and possibly to the extreme upstream end of the exhaust system, such saltwater can reach the inner electrode of an oxygen sensor disposed in the exhaust system. The interaction of saltwater with the various exotic and other dissimilar metals used to construct the exhaust system and the oxygen sensor, causes corrosion and ultimately destroys the oxygen sensor.
Other known oxygen sensor assemblies expose the inner electrode of the oxygen sensor to a conduit leading directly to a combustion chamber within the engine. Although this design better protects the oxygen sensor from water that may be present in the exhaust system, other problems are raised. For example, where the oxygen sensor is directly exposed to the combustion chamber, unburnt hydrocarbons may be pushed into contact with the inner electrode, thereby affecting the performance of the sensor. Additionally, the outer electrode is still exposed to ambient air. As such, other problems are raised in allowing ambient air to contact the outer electrode while preventing water from reaching the outer electrode. Thus, it is desirable to provide a control system for an engine of a marine vehicle which reduces the cost of maintenance and manufacturing and extends the operational life of the engine.
Another aspect of the invention includes the realization that although numerous components of an engine for a marine vehicle may be mass produced with a high level of precision, differences result in the operational characteristics of such components despite efforts to maintain consistency of mass produced items. For example, but without limitation, fuel injectors typically include a solenoid which drives a spring biased valve which is biased to a closed position. The springs are mass produced. However, although the springs may appear to be identical, variations have been found between identically sized springs, which results in a difference in the corresponding spring constant. These differences cause the fuel injectors to behave differently from one another, i.e., the speed at which the valve closes according to its bias. Additionally, it has been found that the injection port diameters of one engine body may be different from the injection port diameters of another engine body which are mass produced on the same manufacturing line. These differences, among others, can affect the performance of the fuel injector, and thus the air/fuel ratio delivered to combustion chamber.
Thus, according to another aspect of the invention, an engine for a marine vehicle includes an engine body defining at least one combustion chamber and the fuel injection system. The fuel injection system is configured to form fuel charges for combustion in the combustion chamber. The engine also includes a controller for controlling fuel injection parameters. The controller includes a memory having a predetermined map which includes fuel injection parameters. The controller includes compensation values derived from a test of the engine during operation and defines a fuel injection compensation value as a function of at least one engine operation characteristic. The fuel injection compensation value is determined by operating the engine, detecting a combustion condition of the engine over a range of engine speeds, and determining the fuel injection compensation value which corresponds to a predetermined air/fuel ratio.
By including a compensation value which is derived from a test of the engine itself, the present engine is more accurately controlled because the controller can compensate for the various differences existing in mass produced components, such as springs and injection port diameters.
According to another aspect of the invention, a method for adjusting an engine controller of a marine vehicle engine comprises installing a combustion condition sensor on an engine so as to expose a portion of the sensor to combustion gases within the engine. The engine is then operated using the combustion condition sensor in a feedback control scenario during which a fuel injection compensation value is determined which corresponds to a pre-determined air/fuel ratio. The combustion condition sensor can then be removed and the engine can then be operated without the sensor. Preferably, the combustion condition sensor is an oxygen sensor.
By adjusting an engine controller in accordance with the present method, the controller can compensate for the varying differences present in mass produced components and the cost of the engine can thereby be reduced because the engine does not need to have a combustion condition sensor, such as an oxygen sensor, for example. Furthermore, since the engine controller does not rely oil a combustion condition sensor for operation, the life span of the engine is extended since combustion condition sensors, such as oxygen sensors, typically suffers greatly from corrosion caused by water in the ambient environment in which a marine vehicle is operating, as well as water present in the exhaust system thereof.
Further aspects, features and advantages of the present invention will become apparent from the detailed description of the preferred embodiments which follow.
BRIEF DESCRIPTION OF THE DRAWINGS
The features mentioned in the summary of the invention, as well as other features of the invention, will now be described with reference to the drawings of a preferred embodiment of an engine for a marine vehicle. The illustrated embodiment is intended to illustrated, but not to limit, the invention. The drawings contain the following figures:
FIG. 1
is a multi-part view showing: in the lower portion, an outboard motor that employs an engine which relates to the present invention; and in the upper view, a partially schematic cross-sectional view of the engine of the outboard motor with its air induction, fuel injection, and exhaust system shown in part schematically. An ECU (electronic control unit) for the motor links the two views together.
FIG. 2
is a partial left side elevational view of the outboard motor shown in
FIG. 1
with an upper and lower cowling member of the outboard motor shown in section.
FIG. 3
is a top plan view of the engine shown in FIG.
2
. The upper cowling is removed and the lower cowling is shown partially.
FIG. 4
includes the same views as FIG.
1
and additionally shows a combustion condition sensor connected to the exhaust system and to the ECU.
FIG. 5
is a flow diagram of a control subroutine for adjusting an engine controller.
FIG. 6
is a graph having voltage (V) plotted on the vertical axis and illustrating three voltage ranges, i.e., a low range, an intermediate range, and a high range.
FIG. 7
is a graph having a compensation value (C) plotted on the vertical axis and engine speed (N) plotted on the horizontal axis.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
An improved engine controller for an engine of a marine vehicle is disclosed herein. The engine includes an improved controller which avoids the need for expensive and water sensitive components. Although the engine is illustrated as being installed on an outboard motor
10
, the engine can be used with any vehicle using an internal combustion engine, such as, for example, but without limitation, personal watercraft, small jetboats, off-road vehicles, circle track racing vehicles, automobiles, and heavy construction equipment.
In the lower portion view of
FIG. 1
, the outboard motor
10
is partially illustrated as being mounted to a transom
12
of a marine vehicle
14
. The entire outboard motor
10
is not depicted. For example, the swivel bracket that is typically associated with an outboard motor is not illustrated. This and other components, not specifically identified herein, are well known in the art and the specific method by which the outboard motor
10
is mounted to the transom
12
of the watercraft
14
is not necessary to prevent those skilled in the art to understand or practice the invention.
With reference to
FIG. 2
, the outboard motor
10
includes a powerhead
16
positioned above a drive shaft housing
18
(
FIG. 1
) and which includes an internal combustion engine, indicated generally by the reference numeral
20
. The engine
20
is shown in more detail in the upper view of FIG.
1
and is described in more detail below.
The powerhead
16
is surrounded by a protective cowling
21
that includes a main cowling member
22
and a lower cowling member or a “lower tray”
24
. The main cowling member
22
is detachably fixed to the lower tray portion
24
. The lower tray portion
24
encloses an upper portion of the driveshaft housing
18
.
With reference to
FIG. 1
, positioned beneath the drive shaft housing
18
, a lower unit
26
is provided in which a propeller
28
, which forms the propulsion device for the associated watercraft, is journaled.
As is typical with outboard motor practice, the engine
20
is supported in the powerhead
16
so that its crankshaft
30
(see upper view of
FIG. 1
) rotates about a vertically extending axis. This facilitates connection of the crankshafts
30
to a drive shaft
32
(see lower view of
FIG. 1
) which depends into the drive shaft housing
18
. The drive shaft
32
drives the propeller
28
through a conventional forward, neutral, reverse transmission
34
contained in a lower unit
26
. The transmission
34
is provided between the drive shafts
32
and a propeller shaft
36
. The transmission
34
couples together the drive shaft
32
and the propeller shaft
36
, which lie generally normal to each other (i.e., at a 90° angle) with a bevel gear combination. In the illustrated embodiment, the bevel gear combination includes a drive bevel gear
38
driven by the drive shaft
32
, and two driven bevel gears
40
,
42
. The driven bevel gears
40
,
42
arc moved into and out of engagement with the drive bevel gear
38
to effect forward and reverse thrust. The movement of the bevel gears
40
,
42
is effected by a dog clutch
44
. In the illustrated embodiment, the dog clutch
44
moves the driven bevel gears
40
,
42
to shift the rotational directions of the propeller
28
between forward, neutral and reverse.
The dog clutch
44
includes a shift cam (not shown). A shift rod
46
is connected to a shift cable
48
. The shift rod
46
extends generally vertically through the drive shaft housing
18
and the lower unit
26
, while the shift cable
48
extends outwardly from the lower cowling
24
and is connected to a shift unit
50
which includes a lever
52
. The lever
52
is movable between a neutral position (illustrated in solid lines), a forward position
52
F (illustrated in phantom lines) and a reverse position
52
R (illustrated in phantom lines). The lever
52
is operable by the operator when the operator wants to shift the transmission
34
directions.
The outboard motor
10
also includes a bracket assembly
54
. Although schematically shown in
FIG. 1
, the bracket assembly
54
comprises a swivel bracket and a clamping bracket. The swivel bracket supports the outboard motor
10
for pivotal movement about a generally vertically extending steering axis. The clamping bracket, in turn, is affixed to the transom
12
of the watercraft
14
and supports the swivel bracket for pivotal movement about a generally horizontally extending axis. A hydraulic tilt system can be provided between the swivel bracket and the clamping bracket to tilt up or down the outboard motor
10
. If this tilt system is not provided, the operator may tilt the outboard motor
10
manually. Since the construction of the bracket assembly
54
is well known in the art, a further description is not believed to be necessary to enable those skilled in the art to practice the invention. As used throughout this description, the terms “forward,” “front,” and “fore” mean at or to the side of the bracket assembly
54
, and the terms “rear,” “reverse,” and “rearwardly” mean at or to the opposite side of the front side, unless indicated otherwise.
With reference to the upper view of
FIG. 1
, the engine
20
operates on a 4-stroke combustion principle, The engine
20
includes a cylinder block
56
. In the illustrated embodiment, the cylinder block
56
defines four cylinder bores
58
which are generally horizontally extending and spaced generally vertically from each other. As such, the engine
20
is an L
4
(inline
4
cylinder) type. A piston
60
reciprocates in each cylinder bore
58
. It is to be noted that the engine may be of any type (V-type, W-type), may have other numbers of cylinders and/or may operate under other principles of operation (2-stroke, rotary, or diesel principles).
A cylinder head assembly
62
is affixed to one end of the cylinder block
56
. The cylinder head assembly
62
includes a cylinder head
63
and defines four combustion chambers
64
with the pistons
60
and the cylinder bores
58
. The other end of the cylinder block
56
is closed with a crankcase member (not shown) defining a crankcase chamber.
The crankshaft
30
extends generally vertically through the crankcase chamber. The crankshaft
30
is connected to the pistons
60
by connecting rods
66
and rotates with the reciprocal movement of the pistons
60
within the cylinder bores
58
. The crankcase member is located at the forward-most position of the powerhead
16
, and the cylinder block
56
and the cylinder head assembly
62
extend rearwardly from the crankcase member.
The engine
20
also includes an air induction system
68
and an exhaust system
70
. The air induction system
68
is configured to supply air charges to the combustion chambers
64
.
With reference to
FIGS. 2 and 3
, the induction system
68
includes a plenum chamber member
72
which defines a plenum chamber
74
therein. Four main intake passages
76
extend from the plenum chamber
74
to a corresponding number of intake ports
78
(
FIG. 1
) formed on the cylinder head assembly
62
.
The intake ports
78
are opened and closed by intake valves
80
. When the intake ports
78
are opened, air from the intake passages
76
and intake ports
78
flows into the combustion chambers
64
.
The plenum chamber
74
is positioned on the port side of the crankcase member. The plenum chamber
74
has an inlet opening (not shown) that opens to the interior of the cowling
22
at its front side. The plenum chamber member
72
functions as an intake silencer and/or a collector of air charges. The air intake passages
76
extend rearwardly from the plenum chamber
74
along the cylinder block
56
and curve toward the intake ports
78
. The respective intake passages
76
are vertically spaced apart from each other.
With reference to
FIG. 2
, the air intake passages
76
are defined by duct sections
82
, throttle bodies
84
, and runners
86
. In the illustrated embodiment, the duct sections
82
are formed integrally with the plenum chamber member
72
.
As shown in
FIG. 2
, the upper two throttle bodies
84
are integrated with each other. The upper two intake runners
86
are also integrated with each other at their fore portions and then forked into two separate portions. The lower two throttle bodies
84
, as viewed in
FIG. 2
, and the corresponding lower two intake runners
86
, have the same construction as the upper two throttle bodies
84
and intake runners
86
, respectively.
The respective throttle bodies
84
support throttle valves
88
(
FIG. 1
) therein for pivotable movement about valve shafts (not shown) which extend generally vertically. The valve shafts are linked together to form a single valve shaft assembly
90
that passes through the throttle bodies
84
.
The throttle valves
88
are operable via a throttle cable
92
and a non-linear control mechanism
94
. The throttle cable
92
is connected to a throttle lever (not shown). Optionally, the shift lever
52
can be constructed so as to operate as both a shift lever for operating the transmission
34
and the non-linear control mechanism
94
.
The non-linear control mechanism
94
includes a first lever
96
connected to a second lever
98
, which are joined together through a cam connection
100
. The first lever
96
is pivotally connected to the throttle cable
92
and also to a first pivot pin connected to the crankcase member. The first lever also defines a cam hole at the end of the first lever
96
opposite the throttle cable
92
. The second lever
98
is generally shaped as the letter “L” and is pivotally connected to a second pin which is affixed to the crankcase member. The second lever has a pin that reciprocates within the cam hole. The other end of the second lever is connected to a control rod
102
. The control rod
102
, in turn, is pivotally connected to a lever member which is connected to the throttle valve shaft assembly
90
via a torsion spring (not shown) that urges the control rod
102
to a closed position.
A throttle valve position sensor
104
., as shown in
FIGS. 1 and 2
, is arranged atop of the throttle valve shaft assembly
90
. A signal from the throttle valve position sensor
104
is directed to an ECU
106
via a throttle valve position signal line
108
for use in controlling various aspects of engine operation including, for example, but without limitation, fuel injection control which will be described later. The signal from the throttle valve position sensor
104
corresponds to the engine load in one aspect, as well as the throttle opening. The ECU
106
is described in detail below.
The air induction system
68
further includes a bypass passage or idle air supply passage
110
(FIG.
1
). An idle air adjusting unit
112
is disposed in the bypass passage
110
for controlling air flow therethrough. The idle air adjusting unit
112
is connected to the ECU
106
via an idle air control line
114
.
With reference to
FIG. 2
, and as noted above, the upper cowling
22
is detachably affixed to the lower cowling
24
so as to generally completely enclose the engine
20
. The upper cowling
22
includes an air intake compartment
116
defined between a top surface
1118
of the upper cowling
22
and a cover member
120
. The intake compartment
116
has an air inlet duct
122
that connects the space in the compartment
116
and the interior of the cowling
21
.
In operation, air is introduced into the air intake compartment
116
and enters the interior of the cowling
21
through the air inlet duct
122
. The air then passes through the inlet opening of the plenum chamber member
72
and enters the plenum chamber
74
. During idle of the engine
20
, an air charge amount is controlled by the throttle valves to meet the requirements of the engine
20
. Tile air charge then flows through the runners
86
and to the intake ports
78
(FIG.
1
).
As described above, the intake valves
80
are provided at the intake ports
78
. When the intake valves are opened, the air supplied to the combustion chambers
64
has an air charge. Under the idle running condition, the throttle valves are generally closed. The air, therefore, enters the port
78
through the idle air adjusting unit
112
which is controlled by the ECU
106
. The idle air charge adjusted in the adjusting unit has been supplied to the combustion chambers
64
via the intake ports
78
.
The exhaust system
70
is configured to discharge or guide burnt charges or exhaust gases outside of the outboard motor
10
from the combustion chamber
64
. Exhaust ports
124
are defined in the cylinder head assembly
62
and are opened and closed by exhaust valves
126
. When the exhaust ports
124
are opened, the combustion chambers
64
communicate with a single or multiple exhaust passages
128
which lead the exhaust gases downstream through the exhaust system
62
.
Preferably, the exhaust system
70
includes an underwater, high speed exhaust gas discharge and an above water, low speed exhaust gas discharge. Since these types of systems are well known in the art, a further description of the exhaust system is not believed to be necessary to prevent those skilled in the art to practice the invention.
An intake camshaft
130
and an exhaust camshaft
132
are provided to control the opening and closing of the induction valves
80
and exhaust valves
126
, respectively. The camshafts
130
,
132
extend approximately vertically and parallel with each other. The camshafts
130
,
132
have cam lobes that act against the valves
80
,
126
at predetermined timings to open and close the respective ports. The camshafts
130
,
132
are journaled on the cylinder head assembly
62
and are driven by the crankshaft
30
via a camshaft drive unit
134
(FIG.
2
).
In the illustrated embodiment, the camshaft drive unit
134
is positioned at the upper end of the engine
20
, as viewed in FIG.
2
. With reference to
FIG. 3
, the camshaft drive unit
134
includes sprockets
136
,
138
mounted to an upper end of the camshafts
130
,
132
, respectively. The crankshaft
30
also includes a sprocket
140
at an upper end thereof. A timing belt or chain
136
is wound around the sprockets
136
,
138
,
140
. As the crankshaft
30
rotates, the camshafts
130
,
132
are thereby driven.
With reference to
FIGS. 1 and 2
, the engine
20
also includes a fuel injection system
144
. The fuel injection system
144
includes four fuel injectors
146
which have injection nozzles exposed to the intake ports
78
so that injected fuel is directed toward the combustion chamber
64
. A main fuel supply tank (not shown) is part of the fuel injection system and is placed in the hull of the associated watercraft
14
. Fuel is drawn from the fuel tank through a series of fuel pumps and preferably, a vapor separator (not shown). A high pressure fuel pump (not shown) draws fuel from the vapor separator and delivers highly pressurized fuel to a fuel rail
148
(FIG.
2
). Preferably, a fuel return conduit (not shown) is also provided between the fuel injectors
146
or the fuel rail
148
and the vapor separator. A pressure regulator (not shown) preferably regulates the pressure within the fuel injection system
144
.
In operation, a predetermined amount of fuel is sprayed into the intake ports
78
via the injection nozzles of the fuel injectors
146
. The timing and duration of the fuel injection is dictated by the ECU
106
. The fuel charge delivered by the fuel injectors
146
then enters the combustion chambers
64
with an air charge at the moment the intake valves
80
are opened. Since the fuel pressure is regulated, a duration during which the nozzles of the injectors are opened is a factor determined by the ECU
106
to measure an amount of fuel to be injected by the fuel injectors
146
. The duration and injection timing are thus controlled by the ECU
106
through a fuel injector control line
148
. Preferably, the fuel injectors
146
are operated by solenoids (not shown) as is known in the art. Thus, the fuel injector control line
148
signals the solenoids to open spring loaded valves within the fuel injectors according to the timing and duration determined by the ECU
106
.
The engine
20
further includes an ignition system, indicated generally by reference numeral
150
. Four spark plugs
152
are affixed on the cylinder head assembly
62
and are exposed into the respective combustion chambers
64
. The spark plugs
152
ignite an air/fuel charge at a certain timing as determined by the ECU
106
to burn the air/fuel charge therein. For this purpose, the ignition system
150
includes an ignition coil
154
interposed between the spark plugs
152
and the ECU
106
. In the illustrated embodiment, the ignition system
150
also includes an ignitor
156
disposed between the ignition coil
154
and the ECU
106
. An ignition control line
158
connects the ignitor
156
and the ECU
106
. Control signals from the ECU
106
are delivered to the ignitor
156
via the control line
158
.
With reference to
FIG. 2
, the flywheel assembly
160
is affixed to an upper end of the crankshaft
30
. A cover member
162
covers the flywheel assembly
160
, sprockets
130
,
132
,
140
and the belt
142
so as to prevent debris and/or foreign materials from becoming entrained in the sprockets
130
,
132
,
140
and to protect an operator from moving components when the upper cowling
22
is removed. The flywheel assembly
160
also includes an AC generator that generates electric power. The generated AC power is led to a battery (not shown) through a rectifier that rectifies the AC power to DC power. The battery accumulates electrical energy therein and also supplies it to electrical equipment including the ECU
106
, the solenoids of the fuel injectors
146
and the ignition coil
154
.
While not illustrated, the engine
20
can also include a recoil starter to drive the flywheel assembly
160
when starting the engine
20
. A starter motor can be employed in addition or in the alternative to the recoil starter for the same purpose. The use of a starter motor is preferred when the present invention is employed with larger size engines. The recoil starter is operated by an operator of the watercraft
14
when the operator wants to start the engine
20
. For example, the starter motor may be activated when a main switch is actuated by the operator of the watercraft
14
.
Preferably, the ECU
106
controls the timing and duration of fuel injection from the fuel injectors
146
and the timing of the firing of the spark plugs
152
according to a feedback control scenario. A number of sensors, in addition to the throttle position sensor
104
, are configured to output signals indicative of corresponding various conditions including, for example, but without limitation, engine operation conditions, ambient conditions or other conditions of the outboard motor
10
that affect engine performance.
Certain sensors are schematically represented in FIG.
1
. For example, an engine speed sensor
170
is mounted in the vicinity of the crankshaft
30
and/or a flywheel
164
which is also attached to the crankshaft
30
. The engine speed sensor
170
outputs a signal indicative of the position of the crankshaft
30
and/or the speed of rotation of the crankshaft
30
. The signal from the engine speed sensor
170
is transferred to the ECU
106
via a crankshaft position dataline
172
.
A crankshaft position sensor
174
is mounted in the vicinity of one of the camshafts
130
,
132
in order to determine the status of the engine, i.e., whether the crankshaft
30
is in an intake and compression rotation or a power and exhaust rotation. For example, since a 4-cycle engine fires its fuel injectors
146
and spark plugs
152
only once for every two rotations of the crankshaft
30
, the camshafts
130
,
132
rotate only once for every two revolutions of the crankshaft
30
. Thus, a crankshaft position sensor
174
can be used to determine the status of the engine since it is mounted in the vicinity of one of the camshafts
130
,
132
.
The output signals from the crankshaft position sensor
174
is transferred to the ECU
106
via a crankshaft position dataline
176
. As such, the ECU
106
can receive the output signal from the crankshaft position sensor
174
for the use in determining proper fuel injection timing and spark plug firing, for example.
An engine temperature sensor
178
can be connected to the engine
20
in order to detect the temperature of the engine
20
. In the illustrated embodiment, the engine temperature sensor
178
is connected to a cooling jacket formed in the cylinder block
56
so as to detect the temperature of engine coolant flowing therethrough. The engine temperature sensor
178
is connected to the ECU
106
via an engine temperature dataline
180
. As such, the ECU
106
can receive a signal from the engine temperature sensor
178
indicative of the temperature of the cylinder block
56
.
A watercraft speed sensor
182
can be connected to the watercraft
14
for detecting a speed of the watercraft
14
. The watercraft speed sensor
182
is connected to the ECU
106
via a watercraft speed dataline
184
. As such, the ECU
106
can receive a signal from the watercraft speed sensor
184
that is indicative of the speed of the associated watercraft
14
.
An intake air temperature sensor
186
can be connected to the induction system
68
to detect the temperature of the air present in the induction system
68
. In the illustrated embodiment, the intake air temperature sensor
186
is connected to the intake passage
76
, downstream from the throttle valve
88
. The intake air temperature sensor
186
is connected to the ECU
106
via intake air temperature dataline
188
. As such, the ECU
106
can receive a signal from the intake air temperature sensor
186
that is indicative of the temperature of air present in the induction passage
76
.
An intake air pressure sensor
190
can also be connected to the induction system
68
. In the illustrated embodiment, the intake air pressure sensor
190
is connected to the intake passage
76
so as to detect a pressure of the intake air present in the intake passage
76
. The induction air pressure sensor
190
is connected to the ECU
106
via an air pressure dataline
192
. As such, the ECU
106
can receive a signal from the intake air pressure sensor
190
that is indicative of the pressure within the intake passage
76
.
The transmission position sensor
194
can be connected to a point on the outboard motor
10
so as to detect a position of the transmission
34
. In the illustrated embodiment, the transmission position sensor
194
is positioned at an upper end of the shift rod
46
so as to detect the state of the transmission
34
, i.e., whether the transmission
34
is in a forward, neutral, or a reverse state. The transmission position sensor
194
is connected to the ECU
106
via a transmission position dataline
196
. As such, the ECU
106
can receive a signal from the transmission position sensor
194
which is indicative of a position of the transmission
34
.
Optionally, a throttle lever position sensor
198
can be mounted to the lever assembly
50
when the assembly
50
is configured to provide the dual functions of a throttle lever and a shift lever. In this mode, the lever position sensor
198
is a rheostat and thus can detect a position of the lever
52
proportionally between the positions
52
,
52
F, and
52
R. The lever position sensor
198
is connected to the ECU
106
via lever position dataline
200
. As such, the ECU
106
can receive a signal from the lever position sensor
198
which is indicative of a proportional position of the lever
52
. In this mode, the ECU
106
can drive a further actuator (not shown) such as an electric motor or stepper solenoid, for electronically controlling a position of the throttle valve
88
in proportion to the position of the lever
52
dictated by a user.
In addition to the sensors described above, additional sensors may be provided for detecting other conditions such as a knock sensor, a fuel pressure sensor, a back pressure sensor, a trim angle sensor, a mount height sensor, an engine vibration sensor, and a watercraft position sensor. Any combination of these sensors in combination with the above-mentioned sensors can be used with various known control strategies.
The ECU
106
, as noted above, outputs signals to the fuel injectors
146
, the spark plugs
152
, for their respective control. Additionally, the ECU
106
can also control the high pressure fuel pump and the throttle valve
88
. Additionally, the ECU
106
can be connected to various other components of the engine
20
including, for example, but without limitation, a lubrication pump (not shown), and a coolant fluid pump (not shown). As noted above, the ECU
106
can control these various components according to any known control strategy.
In the illustrated embodiment, the ECU
106
includes a memory
202
. The memory
202
contains any number of various predetermined multi-dimensional maps or other types of software for controlling the various components of the engine
20
according to any known control strategy. Such maps are typically created through testing of a representative sample of an engine from a mass production line. The data and maps resulting from such testing are used as a basis by the electronic control units for all the engines produced by the mass production line, such as engine
20
.
The present ECU
106
also includes at least one compensation value contained within the memory
202
that is used for controlling fuel injection which is derived from data recorded during a test of the engine
20
. For example, with reference to
FIG. 4
, the present engine
20
is configured to receive a removable combustion condition sensor
204
so as to maintain the combustion condition sensor
204
in contact with exhaust gases from the combustion chamber
64
. For example, the engine
20
can include a combustion condition sensor port
205
configured to receive a combustion condition sensor, such as an oxygen sensor. The engine preferable also includes a plug (not shown) for closing the combustion condition sensor port
205
when the engine
20
is running without combustion condition sensor
204
connected to the port
205
.
Similarly, the ECU
106
preferably includes a releasable sensor input port
206
. Preferably, the port
206
is independent of any other input port on the ECU
106
such that any data or signal line connected thereto can be disconnected independently of any other such input data line. In the illustrated embodiment, the transmission position sensor dataline
200
is typically connected to the sensor port
206
during normal operation of the engine
20
. The combustion condition sensor data line
208
is preferably connected to an input port of the ECU
106
that is normally connected to a sensor which has a different output signal characteristic than the combustion condition sensor
204
. By connecting the combustion condition sensor data line
208
as such, the ECU can more easily determine whether the combustion condition sensor
204
is connected to the input port
206
or whether another sensor is connected to the input port
206
. In the present embodiment, the combustion condition sensor line
208
is connected to the input port
206
which, under normal running conditions, is connected to the transmission position sensor data line
200
. Thus, since the output characteristics of the transmission position sensor
194
is different from a typical combustion condition sensor such as an oxygen sensor, the ECU
106
can readily determine whether the input port
206
is connected to the transmission position sensor
194
or an oxygen sensor used as the combustion condition sensor
204
, discussed in more detail below. Thus, the ECU
106
desirably is configured to determine whether a combustion condition sensor
204
or another sensor having a different characteristic is connected to an input port, such as the input port
206
.
With the combustion condition sensor
204
connected to the exhaust system
70
, the ECU
106
can be operated in a feedback control mode during which engine operating conditions sensed by the various sensors including at least the combustion condition sensor
204
, are recorded in order to determine optimal operating conditions of the engine
20
. For example, the ECU
106
can be configured to run the engine
20
at a number of engine speeds. At each engine speed, the ECU can use the output signal from the combustion condition sensor
204
to determine the proper fuel injection duration needed to achieve a desired air/fuel ratio. Preferably, the ECU
106
will determine the fuel injection duration required to achieve a stocheometrically correct air/fuel mixture within the combustion chamber
64
. Optionally, the ECU
106
can be configured to determine whether the engine
20
is operating at a predetermined test speed, thus relying on an operator to cause the engine to run at the predetermined test speed.
As noted above, the combustion condition sensor
204
can be any known combustion condition sensor capable of outputting a signal indicative of the air/fuel ratio of an air/fuel mixture delivered to the combustion chamber
64
. In a presently preferred embodiment, the combustion condition sensor
204
is an oxygen sensor which can be constructed in accordance with any known oxygen sensor design. For example, the oxygen sensor can be constructed of a catalytic-type oxygen sensor. In this type of oxygen sensor, a sensor element of the oxygen sensor is constructed of a ceramic material such as zirconium oxide (Z
r
O
2
) housed in a gas-permeable platinum electrode. During operation, and in particular temperatures in excess of 300° C., the zirconium dioxide conducts negative oxygen ions. Such as sensors designed to be very responsive at Lambda (Λ), i.e., values in the vicinity of (1), i.e., the output signal changes quickly in response to small changes in the detected air/fuel ratio. For typical gasoline-powered engines, the stocheometrically ideal air/fuel ratio is about 15:1, and more particularly 14.7:1. As is common in the art, A is defined as equal to one (1) when the air/fuel ratio is 14.7:1. Thus, typical oxygen sensors for gasoline-powered internal combustion engines are configured to be very responsive when the air/fuel ratio is about 14.7:1.
A first electrode of the sensor is typically exposed to a reference value of atmospheric air. Thus, a greater quantity of oxygen ions will be present on the first electrode. Through the electrolytic action, the oxygen ions permeate the electrode and migrate through the electrolyte zirconium dioxide. Thus, a charge builds in the sensor as a function of the amount of oxygen ions that are present in the vicinity of the sensor element.
When the sensor element, i.e., the second electrode, is exposed to exhaust emissions formed as a result of the combustion of a rich air/fuel mixture, there is very little free oxygen in the exhaust gas. This small amount of oxygen is readily combined with carbon monoxide (CO) present in the exhaust gas through the catalytic action of the platinum electrode. Thus, the oxygen concentration in the exhaust gas is discharged after combustion of a rich air/fuel charge is relatively low, in contrast with the oxygen content of the atmosphere. Oxygen atoms contacting the atmospheric electrodes gain electrons and travel through the zirconium ceramic to the exhaust electrode where they then shed the extra electron, thus leaving a positive charge on the atmospheric electrode and a negative charge on the exhaust electrode. Through this mechanism, a small voltage of about 0.8 volts can be generated by the sensor.
Conversely, when the outer platinum electrode is subjected to the emissions of the combustion of a lean air/fuel charge, the concentration of free oxygen in the exhaust gas is relatively large. Thus, despite the oxidizing action of the platinum electrode, there is a relatively large amount of oxygen present in the exhaust gases exposed to the sensor element. Because there are oxygen ions present at both the exhaust electrode, i.e., the sensor element and the atmospheric electrode, little electromotive force is generated between the electrodes, thereby leaving a charge of approximately 0 volts in the sensor. Alternatively, other types of oxygen sensors can be used which generate different output voltages corresponding to the detection of rich or lean exhaust gases. Additionally, circuits can be connected to the oxygen sensors to manipulate the output voltages to other ranges.
Thus, during a test of the engine
20
, the ECU
106
operates the fuel injectors
146
according to the predetermined map stored in the memory
202
. The ECU
106
then adjusts the fuel injection duration until corrected fuel injection duration is reached which corresponds to a pre-determined air/fuel ratio, as indicated by the output from the combustion condition sensor
204
. Preferably, the ECU
106
will determine the corrected fuel injection duration required to achieve a stocheometrically correct air/fuel ratio, i.e., Λ values equal to approximately 1. The ECU
106
preferably stores the corrected fuel injection duration as a compensation value (C). Preferably, the compensation value (C) is a percentage of the fuel injection duration dictated by the predetermined map, i.e, +C% for corrected fuel injection duration values greater than that defined in the predetermined map and −C% for corrected fuel injection duration values smaller than defined in the predetermined map.
After determining the corrected fuel injection durations, or compensation values (C%) for a plurality of engine speeds, the ECU
106
generates a map defining a relationship between corrected fuel injection duration and engine speed. Preferably, the map defines a relationship between compensation values (C%) and engine speed.
Thus, by configuring the ECU
106
as noted above, the map created by the ECU
106
is derived from a test of the engine
20
. Thus, the data used to generate the map allows the ECU
106
to compensate for discrete differences or variations that can be generated in identical mass-produced engines. For example, as noted above, fuel injectors typically include a valve at the injection nozzle which is biased to a closed position by a spring. A solenoid acts against the bias of the spring to open the fuel injector according to the fuel injection duration determined the ECU
106
.
1
However, the closing of the valve is dependent on the spring constant of the spring. Thus, variations caused during mass production of the spring affects the performance, and particularly, the actual fuel injection duration performed by the fuel injector
146
. Because fuel injection duration can be affected by the spring, the spring can thereby affect the air/fuel ratio of the air/fuel charge delivered to the combustion chamber
64
.
Thus, by including a map within the ECU
106
that is derived from data recorded during a test of the engine
20
, the ECU can compensate for such a variation in the engine components and thereby can more reliably produce air/fuel charges having any desired air/fuel ratio, without the need for a combustion condition sensor to be connected to the engine at all times.
As noted above, oxygen sensors are expensive. Thus, by constructing the ECU
106
as such and thereby avoiding the need for a combustion condition sensor such as an oxygen sensor, to be present in the engine during operation, the engine
20
can be manufactured more inexpensively. Additionally, as noted above, oxygen sensors are particularly sensitive to corrosion caused by contact with water, due to at least in part, the various dissimilar metals used to construct a typical oxygen sensor. Additionally, because oxygen sensors are most conveniently mounted in an exhaust system, contact with water or water vapor is likely when an oxygen sensor is used with an engine for a marine vehicle which commonly discharge exhaust gases below water, and/or inject water directly into the exhaust system.
FIG. 5
illustrates a control subroutine
220
for practicing the present control scheme for the engine
20
. The control subroutine
220
is initiated by an operator, or automatically, at a step S
1
. As noted above, when an engine such as the engine
20
, whether it is packaged as part of an outboard motor such as the outboard motor
10
, or within the engine compartment of another marine vehicle, such as a personal watercraft, small jet boat, or an inboard/outboard watercraft, the ECU
106
will be provided with any one of numerous known maps that are used for various control strategies, including fuel injection control. Such a map is typically based on a test run of a sampling of engines that have been mass produced.
After initiation, and preferably after the engine has been started and is running, the subroutine moves on to a step S
2
. At the step S
2
, the subroutine
220
determines whether the ECU
106
is connected to the combustion condition sensor
204
or another sensor having a different output characteristic. For example, the ECU
106
can compare the voltage signal received at sensor input port
206
to known voltage ranges associated with the combustion condition sensor
204
.
With reference to
FIG. 6
, three reference voltage ranges are illustrated therein. As shown in
FIG. 6
, a low level voltage range L
1
is defined as a voltage between 0 and 0.5 volts. An intermediate voltage range L
2
is defined as voltages between 0.5 and 4.5 volts. A high voltage range L
3
is defined as voltages between 4.5 and 5.0 volts. It has been found that using certain transmission position sensors and oxygen sensors, the ECU
106
can discriminate between an oxygen sensor and transmission position sensors, depending on the voltage output therefrom. For example, as shown in
FIG. 6
, if the voltage at the sensor input port
206
is below 0.5 volts, the ECU can assume that the transmission position sensor
194
is connected to the sensor input port
206
and that the transmission
34
is in neutral. If the voltage at the sensor input port
206
is between 4.5 and 5.0 volts, i.e., in the high voltage range L
3
, the ECU
106
can also assume that the transmission position sensor
194
is connected to the sensor input port
206
and that the transmission
34
is in either forward or reverse gear. However, if the voltage at the sensor input port
206
is between 0.5 and 4.5 volts, the ECU
106
can assume that the combustion condition sensor
204
is connected to the sensor input port
206
. These “assumptions” are correct since the illustrated transmission position sensor
194
only reflects two states, i.e., “on” or “off.” Thus, by using an oxygen sensor which outputs voltages only between 0.5 and 4.5 volts, such an oxygen sensor can be connected to the same sensor input port as that normally used for the transmission position sensor
194
. As such, the number of sensor input ports of the ECU
106
can be reduced, thereby reducing the cost of the ECU
106
.
If it is determined that the combustion condition sensor
204
is not connected to the ECU
106
, the subroutine
220
returns to step S
2
and repeats. If, however, it is determined that the combustion condition sensor
204
is connected to the input sensor port
206
, the subroutine moves on to a step S
3
.
At the step S
3
, the subroutine
220
determines whether the position of the throttle valve
88
is constant. For example, the ECU
106
can sample the output from the throttle position sensor
104
over time, to determine if the throttle valve is being maintained in a substantially constant position. If it is determined that the throttle angle is not constant, i.e., the throttle valve
88
is moving, control subroutine
220
returns to step S
2
and repeats. If, however, it is determined that the throttle angle is constant, the subroutine
220
moves on to a step S
4
. As such, the control subroutine
220
prevents analysis of the engine operating conditions when the engine speed is being accelerated or decelerated, thereby avoiding potentially erroneous results.
At the step S
4
, the control subroutine
220
determines whether the crankshaft
30
is rotating at a predetermined speed. For example, the ECU
106
can sample the output of the engine speed sensor
170
to determine if the crankshaft
30
is rotating at a predetermined speed. Preferably, the subroutine
220
is performed at a plurality of different engine speeds over the normal operating engine speed range for the engine
20
. If it is determined that the speed of the engine is not a predetennined speed, the control subroutine
220
returns to the step S
4
and repeats. If it is determined that the engine speed is a predetermined engine speed, the subroutine
220
moves on to a step S
5
.
Optionally, the ECU
106
can be configured to change the speed of the engine automatically, to the predetermined speeds. For example, as noted above with respect to the throttle lever position sensor
198
, the ECU
106
can be configured to control the position of the throttle valve by an electric motor or a stepper solenoid. Thus, in this mode, the ECU can be configured to adjust the throttle valve
88
position to achieve the predetermined engine speeds.
At the step S
5
, the subroutine
220
determines whether the actual air/fuel ratio R
A
equals the target air/fuel ratio R
T
. For example, the ECU
106
can sample the output from the combustion condition sensor
204
to determine the actual air/fuel ratio R
A
of the air/fuel charge combusted in the combustion chamber
64
. Preferably, the target air/fuel ratio R
T
will correspond to a Λ value of 1, i.e., 14.7:1. However, it is conceived that the present invention can be used with engines having control strategies that utilize a lean burning mode. Thus, other target air/fuel ratios R
T
can be used. If it is determined that the actual air/fuel ratio R
A
is not equal to the target air/fuel ratio R
T
, the control subroutine
220
moves on to a step S
6
.
At the step S
6
, the control subroutine
220
determines whether the actual air/fuel ratio R
A
is greater than the target air/fuel ratio R
T
. If it is determined that the actual air/fuel ratio R
A
is not greater than the target air/fuel ratio R
T
, the subroutine
220
moves on to a step S
7
.
At the step S
7
, the amount of fuel injected by the fuel injectors
146
is adjusted by compensation factor of −C%. Thus, since it was determined, in the step S
6
, that the actual air/fuel ratio R
A
was not greater than the target air/fuel ratio R
T
, it is assumed that the actual air/fuel ratio R
A
is less than the target air/fuel ratio R
T
. Thus, by adjusting the amount of fuel injected by the fuel injectors
146
by compensation factor of −C%, the air/fuel charge delivered to the combustion chambers
64
is made more lean. After the step S
7
, the subroutine
220
returns to the step S
5
.
If, at the step S
6
, it is determined that the actual air/fuel ratio R
A
is greater than the target air/fuel ratio R
T
, the control subroutine
220
moves on to a step S
8
. At the step S
8
, the amount of fuel injected by the fuel injectors
146
is increased by a compensation factor of +C%. Thus, the air/fuel ratio of the air/fuel charges delivered to the combustion chambers
64
is made more rich, thereby lowering the actual air/fuel ratio R
A
. After the step S
8
, the control subroutine
220
returns to the step S
5
. If it is determined that the actual air/fuel ratio R
A
does not equal the target air/fuel ratio R
1
, the control subroutine
220
will repeat steps S
6
-S
8
as necessary until a final compensation factor, i.e., +C% or −C% is reached which results in an actual air/fuel ratio R
A
that equals the target air/fuel ratio R
T
. If the actual air/fuel ratio R
A
equals the target air/fuel ratio R
T
at step S
5
, the control subroutine
220
moves on to a step S
9
.
At the step S
9
, the compensation factor ±C% is stored in the ECU
106
. For example, the ECU
106
can store the compensation factor ±C% in the memory
202
or another memory. Preferably, the ECU
106
stores compensation factors +C in a two-dimensional map such as the two-dimensional map illustrated in
FIG. 7
, discussed in more detail below with reference to FIG.
7
. After the compensation factor ±C% is stored, the subroutine
220
moves on to a step S
10
.
At the step S
10
, the control subroutine
220
signals the operator that the compensation value has been stored. For example, the control subroutine
220
can cause the ECU or any other electrical component to energize a buzzer and/or a lamp for a first period of time. After the step S
10
, the control subroutine
220
moves on to a step S
11
.
At the step S
11
, the control subroutine
220
determines whether all of the predetermined speeds have been completed. For example, as noted above, the control subroutine
220
can be configured to repeat steps S
4
-S
10
for a plurality of engine speeds. If it is determined that all the predetermined speeds have not been completed, the subroutine
220
returns to step S
4
and repeats.
With reference to
FIG. 7
, as the subroutine
220
repeats steps S
4
-S
11
, the subroutine
220
causes a plurality of compensation factors, such as C
1
, C
2
, C
3
, C
4
, and C
5
, for example. The compensation factors C
1
-C
5
represent actual compensation factors stored during the steps S
5
-S
11
, and correspond to engine speeds of N
1
-N
5
, respectively, as illustrated in FIG.
7
. Preferably, the ECU
106
also generates interperlations I
1
, I
2
, I
3
, and I
4
between the compensation factors C
1
and C
2
, C
2
and C
3
, C
3
and C
4
, and C
4
and C
5
, respectively. The combination of the interperlations I
1
-I
4
and the compensation factors C
1
-C
5
, respectively, thereby defining a relationship between a compensation factor C and engine speed N. Thus, during normal operation of the engine
20
after the combustion condition sensor
204
has been removed, the engine
20
can operate using the predetermined control map, as noted above, along with the relationship between compensation factor C and engine speed N illustrated in
FIG. 7
to correct the fuel injection amount and thereby more accurately generate the desired air/fuel ratio within the combustion chamber
64
.
With reference to
FIG. 5
, if it is determined, at the step S
11
, that all of the predetermined speeds have been completed, the subroutine
220
moves on to a step S
12
.
At the step S
12
, the subroutine
220
signals the operator. For example, the subroutine
220
can cause the ECU
106
to energize a lamp and/or a buzzer for a second period of time. Preferably, the second period of time is longer than the first period of time, noted above with respect to the step S
10
. Thus, an operator can distinguish between signals generated after the storing of individual compensation factors and the completion of all of the predetermined engine speeds. Optionally, the control subroutine
220
, at the step S
12
, can instruct the ECU
106
to store the interperlations I
1
-I
4
illustrated in FIG.
7
. After the step S
12
, the subroutine
220
moves on to a step S
13
.
At the step S
13
, the subroutine
220
determines whether the combustion condition sensor is disconnected and another sensor is connected. For example, the subroutine
220
can cause the ECU
106
to sample the output at the sensor input port
206
and determine whether the voltage thereat is less than 0.5 volts, i.e., in the low voltage range, or if the voltage at the sensor input port
206
is above 4.5 volts, i.e., the high voltage range. If it is determined that another sensor has not been connected, the subroutine
220
returns to step S
13
and repeats. If, however, it is determined that another sensor has been connected, the subroutine
220
moves on to a step S
14
and ends thereat.
After performing the control subroutine
220
, the combustion condition sensor
204
is preferably removed from the port
205
. Thus, after removal of the combustion condition sensor
204
, the plug noted above, is preferably installed to close the port
205
.
It is conceived that a control subroutine
220
can be used with any vehicle using an internal combustion engine, such as, for example, but without limitation, personal watercraft, small jetboats, off-road vehicles, circle track racing vehicles, automobiles, and heavy construction equipment.
As noted above, by installing a combustion condition sensor and running a test of the engine
20
to adjust the fuel injection amount injected by the fuel injectors
146
, the present invention can compensate for variations in engine components that are mass produced, without the need for including a combustion condition sensor at all times during operation, while accurately producing a desired air/fuel ratio in the combustion chambers
64
of the engine
20
. Thus, the overall cost of the engine
20
can be reduced. Furthermore, since the combustion condition sensor
204
is not disposed in the engine during operation, the combustion condition sensor
204
is not exposed to the damaging effects of water which have been found to be particularly destructive to typical oxygen sensors.
Additionally, by configuring the ECU to “learn” to compensate an amount of fuel injected by the fuel injectors
146
, as noted above, it is conceived that the ECU
106
can “relearn” compensation values an unlimited number of times over the useful lifespan of the engine
20
. For example, the control subroutine
220
can be performed during an annual tune-up of the engine
20
. Thus, as the various engine components within the engine
20
age and experience wear or otherwise experience changes in performance which can affect the ability of the fuel injection system
68
to generate the desired air/fuel ratio within the combustion chamber
64
, the ECU
106
can compensate for these additional variations.
It is to be noted that the ECU
106
may be in the form of a hard wired feedback control circuit configured to perform the subroutine
220
. Alternatively, the ECU
106
may be constructed of a dedicated processor and a memory for storing a computer program configured to perform the steps S
1
-S
14
. Additionally, the ECU
106
may be constructed of a general purpose computer having a general purpose processor and a memory for storing a computer program for performing the subroutine
220
.
Of course, the foregoing description is that of certain features, aspects and advantages of the present invention to which various changes and modifications may be made without departing from the spirit and scope of the present invention.
Moreover, one engine for a marine vehicle may not feature all objects and advantages discussed above to use certain features. aspects and advantages of the present invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. The present invention, therefore, should only be defined by the appended claims.
Claims
- 1. An engine comprising an engine body, a fuel supply system configured to supply fuel to the engine body, the fuel supply system including at least a first air/fuel charge former, and a controller configured to control operation of the first air/fuel charge former based on output received from a sensor connected to the engine, a memory configured to store a plurality of outputs of the sensor, the controller being further configured to control operation of the fuel supply system without the sensor being connected to the engine, based on the stored outputs of the sensor when the sensor was connected to the engine.
- 2. The engine according to claim 1, wherein the sensor is an air/fuel sensor.
- 3. The engine according to claim 1, wherein the sensor is an oxygen sensor.
- 4. The engine according to claim 1, wherein the memory comprises a map configured to store data received from the sensor and to operate the engine based on the stored data.
- 5. The engine according to claim 1, additionally comprising a map defining a relationship between a fuel supply parameter and a first engine operation parameter, the controller being configured to determine compensation values corresponding to the first engine operation parameter based on the output from the sensor.
- 6. An engine for a marine vehicle comprising an engine body defining at least one combustion chamber, a fuel-injection system including at least one fuel injector for forming fuel charges for combustion in the combustion chamber, an induction system for delivering air to the combustion chamber for combustion with the fuel charges, a controller connected to the fuel injector and configured to control operation of the fuel injector, the controller having a memory, the memory including a predetermined map defining fuel injection duration as a function of at least one engine operation characteristic and at least one compensation value derived from an actual air/fuel ratio of combustion gases from the engine detected by an air/fuel ratio sensor, the controller being configured to control operation of the engine without an air/fuel ratio sensor connected to the controller.
- 7. The engine according to claim 6 additionally comprising a two-dimensional map defining a plurality of fuel injection compensation values as a function of engine speed.
- 8. An engine for a marine vehicle comprising an engine body defining a plurality of combustion chambers, an exhaust system for guiding exhaust gases from the combustion chambers to the atmosphere, a fuel-injection system including a plurality of fuel injectors for delivering fuel charges to the combustion chambers, an induction system for delivering air to the combustion chambers for combustion with the fuel charges, a throttle valve disposed in the induction system for controlling an amount of air entering the combustion chambers when the engine is operating, an oxygen sensor mount configured to receive an oxygen sensor and suspend an oxygen sensor in contact with exhaust gases produced through combustion of the induction air and fuel charges in the combustion chambers, a controller connected to the fuel injectors and configured to control injection timing and duration of fuel injection from the fuel injectors, the controller having a memory, the memory including a predetermined multi-dimensional map defining fuel injection duration and timing as a function of at least engine speed and throttle position, the controller also including a two-dimensional map defining fuel injection duration compensation values as a function of engine speed, the relationship between fuel injection duration compensation values and engine speed being derived from data recorded during a test of the engine with an oxygen sensor disposed in the oxygen sensor mount, the controller being configured to operate the engine without an oxygen sensor disposed in the oxygen sensor mount during normal operation.
- 9. An engine for a marine vehicle comprising an engine body defining at least one combustion chamber, a fuel-injection system including at least one fuel injector for forming fuel charges for combustion in the combustion chamber, an induction system for delivering air to the combustion chamber for combustion with the fuel charges, a controller connected to the fuel injector and configured to control operation of the fuel injector, the controller having a memory, the memory including a predetermined map defining fuel injection duration as a function of at least one engine operation characteristic and at least one compensation value derived from an actual air/fuel ratio of combustion gases from the engine, and a releaseable input signal port provided on the controller.
- 10. The engine according to claim 9, wherein the releasable input signal port is independent of any other input port on the controller.
- 11. The engine according to claim 9, wherein the controller is configured to determine whether a combustion condition sensor or another sensor is connected to the releasable port.
- 12. The engine according to claim 9, wherein the controller is configured to determine the type of sensor connected to the releasable port based on the output signal characteristic detected thereat.
- 13. An engine for a marine vehicle comprising an engine body defining at least one combustion chamber, a fuel-injection system including at least one fuel injector for forming fuel charges for combustion in the combustion chamber, an induction system for delivering air to the engine body for mixing with the fuel charges to form an air/fuel charge for combustion in the combustion chamber, a throttle valve disposed in the induction system for controlling an amount of air entering the combustion chambers when the engine is operating, a controller connected to the fuel injector and configured to control operation of the fuel injector, the controller including a memory having a predetermined map defining a relationship between fuel injection duration and at least one engine operation characteristic, the controller being configured to determine an air fuel ratio of an air/fuel charge combusted in the combustion chamber, determine at least one compensation value for adjusting a fuel injection duration value in the predetermined map to achieve a predetermined air/fuel ratio, store the compensation value, the controller being configured to operate the fuel injection system based on the map and the stored compensation value, without an air/fuel ratio sensor being installed on the engine.
- 14. The engine according to claim 13, wherein the controller is configured to store a plurality of compensation values for a plurality of respective engine speeds.
- 15. The engine according to claim 14, wherein the controller is configured to interpolate between the plurality of compensation factors to define a relationship between compensation factors and engine speed over an engine speed range.
- 16. The engine according to claim 13, wherein the controller is configured to emit a first signal indicating that a compensation factor has been determined.
- 17. The engine according to claim 16, wherein the controller is configured to emit the first signal for a first predetermined period of time.
- 18. The engine according to claim 17, wherein the controller is configured to emit a second signal indicating that a plurality of compensation values have been stored, and to emit the signal for a second period of time being greater than the first period of time.
- 19. An engine for a marine vehicle comprising an engine body defining at least one combustion chamber, a fuel-injection system including at least one fuel injector for forming fuel charges for combustion in the combustion chamber, an induction system for delivering air to the engine body for mixing with the fuel charges to form an air/fuel charge for combustion in the combustion chamber, a throttle valve disposed in the induction system for controlling an amount of air entering the combustion chambers when the engine is operating, a controller connected to the fuel injector and configured to control operation of the fuel injector, the controller including a memory having a predetermined map defining a relationship between fuel injection duration and at least one engine operation characteristic, the controller including means for determining a plurality of compensation values as a function of engine speed and output from an engine operation characteristic sensor configured to detect the at least one engine operation characteristic for adjusting the fuel injection duration values defined in the predetermined map, and means for operating the engine without the engine operation characteristic sensor being connected to the engine.
- 20. An engine for a marine vehicle comprising an engine body defining at least one combustion chamber, a fuel-injection system including at least one fuel injector for forming fuel charges for combustion in the combustion chamber, an induction system for delivering air to the engine body for mixing with the fuel charges to form an air/fuel charge for combustion in the combustion chamber, a throttle valve disposed in the induction system for controlling an amount of air entering the combustion chambers when the engine is operating, a controller connected to the fuel injector and configured to control operation of the fuel injector, the controller including a memory having a predetermined map defining a relationship between fuel injection duration and at least one engine operation characteristic, the controller including means for determining an air fuel ratio of an air/fuel charge combusted in the combustion chamber, means for determining at least one compensation value for adjusting a fuel injection duration value in the predetermined map to achieve a predetermined air/fuel ratio, means for storing the compensation value, and means for operating the fuel injection system based on the map and the stored compensation value, without an air/fuel ratio sensor being installed on the engine.
- 21. The engine according to claim 20 additionally comprising means for interpolating between a plurality of the compensation values to define a relationship between compensation values and engine speed over an engine speed range.
- 22. The engine according to claim 20 dditionally comprising means for signaling an operator when a compensation value has been determined.
- 23. The engine according to claim 20 additionally comprising means for signaling an operator when a plurality of compensation values has been determined for a desired plurality of engine speeds.
- 24. A method for adjusting a fuel injector controller of a fuel-injected marine vehicle engine which includes at least one combustion chamber and a fuel injection system, the method comprising the steps of operating the fuel injection system according to a predetermined map defining fuel injection operation parameters, detecting an air/fuel ratio of an air/fuel charge combusted within a combustion chamber of the engine, comparing the detected air/fuel ratio with a target air/fuel ratio, determining a compensation value for a fuel injection parameter if the detected air/fuel ratio is not the target air/fuel ratio, storing the compensation value, and determining if an air/fuel ratio sensor is connected to the controller.
- 25. A method for adjusting a fuel injector controller of a fuel-injected marine vehicle engine which includes at least one combustion chamber and a fuel injection system, the method comprising the steps of operating the fuel injection system according to a predetermined map defining fuel injection operation parameters, detecting an air/fuel ratio of an air/fuel charge combusted within a combustion chamber of the engine, comparing the detected air/fuel ratio with a target air/fuel ratio, determining a compensation value for a fuel injection parameter if the detected air/fuel ratio is not the target air/fuel ratio, storing the compensation value, and determining a type of a sensor connected to the controller by comparing an output signal characteristic of the sensor with predetermined voltage ranges.
- 26. A method for adjusting a fuel injector controller of a fuel-injected marine vehicle engine which includes at least one combustion chamber and a fuel injection system, the method comprising the steps of operating the fuel injection system according to a predetermined map defining fuel injection operation parameters, detecting an air/fuel ratio of an air/fuel charge combusted within a combustion chamber of the engine, comparing the detected air/fuel ratio with a target air/fuel ratio, determining a compensation value for a fuel injection parameter if the detected air/fuel ratio is not the target air/fuel ratio, and storing the compensation value, wherein the predetermined map comprises a multi-dimensional map stored in a memory of a controller connected to the fuel injection system of the engine, the map defining at least one relationship between fuel injection duration and a second engine operation characteristic.
- 27. A method for adjusting a fuel injector controller of a fuel-injected marine vehicle engine which includes at least one combustion chamber and a fuel injection system, the method comprising the steps of operating the fuel injection system according to a predetermined map defining fuel injection operation parameters, detecting an air/fuel ratio of an air/fuel charge combusted within a combustion chamber of the engine, comparing the detected air/fuel ratio with a target air/fuel ratio, determining a compensation value for a fuel injection parameter if the detected air/fuel ratio is not the target air/fuel ratio, and storing the compensation value, wherein the step of determining a compensation value comprises determining a plurality of compensation values.
- 28. The method according to claim 27 additionally comprising interpolating between the plurality of compensation values to define a relationship between the compensation values and the second engine operation characteristic over a range of values of the second engine operation characteristic.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-217777 |
Jul 1999 |
JP |
|
US Referenced Citations (9)
Foreign Referenced Citations (6)
Number |
Date |
Country |
58-150071 |
Sep 1983 |
JP |
59-201941 |
Nov 1984 |
JP |
61-87941 |
May 1986 |
JP |
61-210250 |
Sep 1986 |
JP |
4-203236 |
Jul 1992 |
JP |
5-59988 |
Mar 1993 |
JP |