Information
-
Patent Grant
-
6612882
-
Patent Number
6,612,882
-
Date Filed
Friday, December 28, 200122 years ago
-
Date Issued
Tuesday, September 2, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Morano; S. Joseph
- Olson; Lars A.
Agents
- Armstrong, Westerman & Hattori, LLP
-
CPC
-
US Classifications
Field of Search
US
- 440 1
- 440 75
- 440 86
- 440 87
- 123 3391
- 123 33911
- 123 33912
- 123 33914
- 123 33921
- 123 33922
- 123 33926
- 123 336
-
International Classifications
-
Abstract
An idling speed control system for an outboard motor mounted on a boat and equipped with an internal combustion engine, whose output is connected to a propeller through a clutch, having secondary air supplier that supplies secondary air. In the system, a difference of preceding and present current command values each indicative of a desired secondary air supply amount is comparing with a predetermined value when the clutch is changed, and the current command value is increased or decreased by a predetermined correction amount when the difference is greater than the predetermined value. With this, it can surely improve the control stability and suppress the overshooting or undershooting of engine speed due to the load change when the clutch is changed, thereby enabling to eliminate or reducing the shock to be felt by the operator and improving the feeling of the operator.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an idling speed control system for an outboard motor, particularly to an idling speed control system for an outboard motor for small boats
2. Description of the Related Art
Small motor-driven boats are generally equipped with a propulsion unit including an internal combustion engine, propeller shaft and propeller integrated into what is called an outboard motor or engine. The outboard motor is mounted on the outside of the boat and the output of the engine is transmitted to the propeller through a clutch and the propeller shaft. The boat can be propelled forward or backward by moving the clutch from Neutral to Forward or Reverse position.
The idling speed of this type of the engine is controlled by use of a secondary air supplier that supplies secondary air through a passage that is connected to the air intake pipe downstream of the throttle valve. The passage is equipped with a secondary air control valve and the desired idling speed is obtained by regulating the opening of the secondary air control valve.
The amount of secondary air required to achieve the desired idling speed varies with aged deterioration of the engine. It also differs with clutch position. This is because the idling speed differs between that when the clutch is in Neutral and that when it is in Forward or Reverse and the outboard engine is running forward or backward at very low speed, i.e., during trolling.
To give a specific example, say that the idling speed is 750 rpm when the clutch is in Neutral. When the clutch is then shifted into Forward or Reverse for low-speed trolling, since the hull acts to load and a quite low speed is required, the engine speed to fall to the trolling speed (herein defined as the idling speed during trolling) of around 650 rpm. The required amount of secondary air changes as a result.
With this, when the engine speed changes form the trolling speed to the idling speed and vice versa, as illustrated in
FIG. 17
, the engine speed may sometimes rise or drop sharply. The overshooting or undershooting of the engine speed from a desired speed due to the clutch change produce shock and hence, degrades feeling of the operator.
Further, if the operator of the outboard motor should replace the propeller, which is not uncommon, the resulting load change will change the engine speed and, accordingly, change the amount of secondary air required to achieve the desired idling speed.
As a result, when the manipulated value in the idling speed control is fixed to a value such that a desired idling speed is achieved, the stability of control is not satisfactory against the load change.
A possible technique to overcome the problem will be to determine the amount of secondary air required to achieve the desired idling speed through a learning control. However, the learning control is generally effective in steady state engine operation, but is less effective in the transient engine operation in which the clutch change results in switching of the idling speed to the trolling speed and vice versa. Thus, even if the learning control is introduced, this can not improve the control stability and can not surely suppress the overshooting or undershooting of engine speed due to the load change.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to solve the problem by providing an idling speed control system for an outboard motor that is equipped with an internal combustion engine which supplies secondary air in such amount as to reduce difference between a desired idling speed determined in response to the clutch position and a detected engine speed, which can surely improve the control stability and suppress the overshooting or undershooting of engine speed due to the load change when the clutch is changed, thereby enabling to eliminate or reducing the shock to be felt by the operator during the clutch change and improving the feeling of the operator.
For realizing this object, there is provided a system for controlling an idling speed for an outboard motor mounted on a boat and equipped with an internal combustion engine whose output is connected to a propeller through a clutch such that the boat is propelled forward or reverse when the clutch is changed to a neutral position to a forward position or a reverse position, comprising: secondary air supplier that supplies secondary air trough a passage that is connected to an air intake pipe downstream of a throttle valve and that is equipped with a secondary air control valve such that amount of secondary air is supplied to the air intake pipe in response to an opening of the secondary air control valve; clutch position detecting means for detecting a position of the clutch; engine operating condition detecting means for detecting parameters indicative of operating conditions of the engine including at least an engine speed; desired value determining means for determining a desired idling speed based on the detected position of the clutch and for determining a desired secondary air supply amount such that a difference between the determined desired idling speed and the detected engine speed decreases; and valve controlling means for controlling the opening of the valve to a value that effects the desired secondary air supply amount; wherein the desired value determining means including: comparing means for calculating a change of the desired secondary air supply amount and for comparing the change with a predetermined value when it is determined based on the detected position of the clutch that the clutch is changed; change direction determining means for determining whether the change is in an increasing direction or in a decreasing direction; and correcting means for correcting the desired secondary air supply amount by a predetermined correction amount in the determined direction, when the change is greater than the predetermined value.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic view showing the overall configuration of an idling speed control system for an outboard motor equipped with an internal combustion engine according to an embodiment of the present invention;
FIG. 2
is an enlarged side view of one portion of
FIG. 1
;
FIG. 3
is a schematic diagram showing details of the engine of the motor shown in
FIG. 1
;
FIG. 4
is a block diagram setting out the particulars of inputs/outputs to and from the electronic control unit (ECU) shown in
FIG. 1
;
FIG. 5
is a main flow chart showing the sequence of operations for calculating a current command value for a secondary air control valve (a value representing a desired amount of secondary air) during operation of the idling speed control system for the engine of the motor shown in
FIG. 1
;
FIG. 6
is a graph for explaining the characteristic of a feedback execution speed NA referred to in the flow chart of
FIG. 5
;
FIG. 7
is the former half of a subroutine flow chart showing the sequence of operations for calculating the current command value IFB in the flow chart of
FIG. 5
;
FIG. 8
is the latter half of the subroutine flow chart showing the sequence of operations for calculating the current command value IFB in the flow chart of
FIG. 5
;
FIG. 9
is a time chart for explaining, inter alia, processing conducted in the subroutine flow chart of
FIGS. 7 and 8
;
FIG. 10
is a graph for explaining the characteristic of predetermined values DIFBHEX 1, 2 referred to in the flow chart of
FIG. 8
;
FIG. 11
is subroutine flow chart showing the sequence of operations for calculating the learning control value IXREF in the subroutine flow chart of
FIG. 7
;
FIG. 12
is a subroutine flow chart showing the sequence of operations for calculating the learning control value IXREF in the subroutine flow chart of
FIG. 11
;
FIG. 13
is a graph for explaining the characteristic of a smoothing coefficient used to calculate the learning control value in the subroutine flow chart of
FIG. 11
;
FIG. 14
is a subroutine flow chart showing the sequence of operations for limit-check processing of the learning control value IXREF in the subroutine flow chart of
FIG. 11
;
FIG. 15
is a flow chart showing the sequence of operations for calculating a desired idling speed during operation of the idling speed control system for the engine of the motor shown in
FIG. 1
;
FIG. 16
is a graph for explaining a characteristic of the desired idling speed calculated in the flow chart of
FIG. 15
; and
FIG. 17
is a time chart explaining a problem in the prior art idling speed control system for an outboard motor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
An idling speed control system for an outboard motor according to an embodiment of the present invention will now be explained with reference to the attached drawings.
FIG. 1
is a schematic view showing the overall configuration of the idling speed control system for an outboard motor and
FIG. 2
is an enlarged side view of one portion of FIG.
1
.
Reference numeral
10
in
FIGS. 1 and 2
designates the aforesaid propulsion unit including an internal combustion engine, propeller shaft and propeller integrated into what is hereinafter called an “outboard motor.” The outboard motor
10
is mounted on the stern of a boat (small craft)
12
by a clamp unit
14
(see FIG.
2
).
As shown in
FIG. 2
, the outboard motor
10
is equipped with the internal combustion engine (hereinafter called the “engine”)
16
. The engine
16
is a spark-ignition V-6 gasoline engine. The engine is positioned above the water surface and is enclosed by an engine cover
20
of the outboard motor
10
. An electronic control unit (ECU)
22
composed of a microcomputer is installed near the engine
16
enclosed by the engine cover
20
.
As shown in
FIG. 1
, a steering wheel
24
is installed in the cockpit of the boat
12
. When the operator turns the steering wheel
24
, the rotation is transmitted to a rudder (not shown) fastened to the stern through a steering system not visible in the drawings, changing the direction of boat advance.
A throttle lever
26
is mounted on the right side of the cockpit and near it is mounted a throttle lever position sensor
30
that outputs a signal corresponding to the position of the throttle lever
26
set by the operator.
A shift lever
32
is provided adjacent to the throttle lever
26
and next to it is installed a neutral switch
34
that outputs an ON signal when the operator puts the shift lever
32
in Neutral and outputs an OFF signal when the operator puts the shift lever
32
in Forward or Reverse. The outputs from the throttle lever position sensor
30
and neutral switch
34
are sent to the ECU
22
through signal lines
30
a
and
34
a.
The output of the engine
16
is transmitted through a crankshaft and a drive shaft (neither shown) to a clutch
36
of the outboard engine
10
located below the water surface. The clutch
36
is connected to a propeller
40
through a propeller shaft (not shown).
The clutch
36
, which comprises a conventional gear mechanism, is omitted from the drawing. It is composed of a drive gear that rotates unitarily with the drive shaft when the engine
16
is running, a forward gear, a reverse gear, and a dog (sliding clutch) located between the forward and reverse gears that rotates unitarily with the propeller shaft. The forward and reverse gears are engaged with the drive gear and rotate idly in opposite directions on the propeller shaft.
The ECU
22
is responsive to the output of the neutral switch
34
received on the signal line
34
a
for driving an actuator (electric motor)
42
via a drive circuit (not shown) so as to realize the intended shift position. The actuator
42
drives the dog through a shift rod
44
.
When the shift lever
32
is put in Neutral, the engine
16
and the propeller shaft are disconnected and can rotate independently. When the shift lever
32
is put in Forward or Reverse position, the dog is engaged with the forward gear or the reverse gear and the rotation of the engine
16
is transmitted through the propeller shaft to the propeller
40
to drive the propeller
40
in the forward direction or the opposite (reverse) direction and thus propel the boat
12
forward or backward.
The engine
16
will now be explained with reference to
FIGS. 3 and 4
.
As shown in
FIG. 3
, the engine
16
is equipped with an air intake pipe
46
. Air drawn in through an air cleaner (not shown) is supplied to intake manifolds
52
provided one for each of left and right cylinder banks disposed in V-like shape as viewed from the front, while the flow thereof is adjusted by a throttle valve
50
, and finally reaches an intake valves
54
of the respective cylinders. An injector
56
(not shown in
FIG. 3
) is installed in the vicinity of each intake valve (not shown) for injecting fuel (gasoline).
The injectors
56
are connected through two fuel lines
58
provided one for each cylinder bank to a fuel tank (not shown) containing gasoline. The fuel lines
58
pass through separate fuel pumps
60
a
and
60
b
equipped with electric motors (not shown) that are driven via a relay circuit
62
so as to send pressurized gasoline to the injectors
56
. Reference numeral
64
designates a vaporized fuel separator.
The intake air is mixed with the injected gasoline to form an air-fuel mixture that passes into the combustion chamber (not shown) of each cylinder, where it is ignited by a spark plug
66
(not shown in
FIG. 3
) to burn explosively and drive down a piston (not shown). The so-produced engine output is taken out through a crankshaft. The exhaust gas produced by the combustion passes out through exhaust valves
68
into exhaust manifolds
70
provided one for each cylinder bank and is discharged to the exterior of the engine.
As illustrated, a branch passage
72
for secondary air supply is formed to branch off from the air intake pipe
46
upstream of the throttle valve
50
and rejoin the air intake pipe
46
downstream of the throttle valve
50
. The branch passage
72
is equipped with an electronic secondary air control valve (EACV)
74
.
The EACV
74
is connected to the ECU
22
. As explained further later, the ECU
22
calculates a current command value that it supplies to the EACV
74
so as to drive the EACV
74
for regulating the opening of the branch passage
72
. The branch passage
72
and the EACV
74
thus constitute a secondary air supplier
80
for supplying secondary air in proportion to the opening of the EACV
74
.
The throttle valve
50
is connected to an actuator (stepper motor)
82
. The actuator
82
is connected to the ECU
22
. The ECU
22
calculates a current command value proportional to the output of the throttle lever position sensor
30
and supplies it to the actuator
82
through a drive circuit (not shown) so as to regulate the throttle opening or position TH.
More specifically, the actuator
82
is directly attached to a throttle body
50
a
housed in the throttle valve
50
with its rotating shaft (not shown) oriented to be coaxial with the throttle valve shaft. In other words, the actuator
82
is attached to the throttle body
50
a
directly, not through a linkage, so as to simplify the structure and save mounting space.
Thus, in this embodiment, the push cable is eliminated and the actuator
82
is directly attached to the throttle body
50
a
for driving the throttle valve
50
.
The engine
16
is provided in the vicinity of the intake valves
54
and the exhaust valves
68
with a variable valve timing system
84
. When engine speed and load are relatively high, the variable valve timing system
84
switches the valve open time and lift to relatively large values (Hi V/T). When the engine speed and load are relatively low, it switches the valve open time and lift to relatively small values (Lo V/T).
The exhaust system and the intake system of the engine
16
are connected by EGR (exhaust gas recirculation) passages
86
provided therein with EGR control valves
90
. Under predetermined operating conditions, a portion of the exhaust gas is returned to the air intake system.
The actuator
82
is connected to a throttle position sensor
92
responsive to rotation of the throttle shaft for outputting a signal proportional to the throttle opening or opening TH. A manifold absolute pressure sensor
94
is installed downstream of the throttle valve
50
for outputting a signal proportional to the manifold absolute pressure PBA in the air intake pipe (engine load). In addition, an atmospheric air pressure sensor
96
is installed near the engine
16
for outputting a signal proportional to the atmospheric air pressure PA.
An intake air temperature sensor
100
installed downstream of the throttle valve
50
outputs a signal proportional to the intake air temperature TA. Three overheat sensors
102
installed in the exhaust manifolds
70
of the left and right cylinder banks output signals proportional to the engine temperature. A coolant temperature sensor
106
installed at an appropriate location near the cylinder block
104
outputs a signal proportional to the engine coolant temperature TW.
O
2
sensors
110
installed in the exhaust manifolds
70
output signals reflecting the oxygen concentration of the exhaust gas. A knock sensor
112
installed at a suitable location on the cylinder block
104
outputs a signal related to knock.
The explanation of the outputs of the sensors and the inputs/outputs to/from the ECU
22
will be continued with reference to FIG.
4
. Some sensors and signals lines do not appear in FIG.
3
.
The motors of the fuel pumps
60
a
and
60
b
are connected to an onboard battery
114
and detection resistors
116
a
and
116
b
are inserted in the motor current supply paths. The voltages across the resistors are input to the ECU
22
through signal lines
118
a
and
118
b.
The ECU
22
determines the amount of current being supplied to the motors from the voltage drops across the resistors and uses the result to discriminate whether any abnormality is present in the fuel pumps
60
a
and
60
b.
TDC (top dead center) sensors
120
and
122
and a crank angle sensor
124
are installed near the engine crankshaft for producing and outputting to the ECU
22
cylinder discrimination signals, angle signals near the top dead centers of the pistons, and a crank angle signal once every 30 degrees. The ECU
22
calculates the engine speed NE from the output of the crank angle sensor. Lift sensors
130
installed near the EGR control valves
90
produce and send to the ECU
22
signals related to the lifts (valve openings) of the EGR control valves
90
.
The output of the F terminal (ACGF)
134
of an AC generator (not shown) is input to the ECU
22
. Three hydraulic (oil pressure) switches
136
installed in the hydraulic circuit (not shown) of the variable valve timing system
84
produces and outputs to the ECU
22
a signal related to the detected hydraulic pressure. A hydraulic switch
140
installed in the hydraulic circuit (not shown) of the engine
16
produces and outputs to the ECU
22
a signal related to the detected hydraulic pressure.
The ECU
22
, which is composed of a microcomputer as mentioned earlier, is equipped with an EEPROM (electrically erasable and programmable read-only memory)
22
a
for back-up purposes. The ECU
22
uses the foregoing inputs to carry out processing operations explained later. It also turns on a PGM lamp
146
when the PGM (program/ECU) fails, an overheat lamp
148
when the engine
16
overheats, a hydraulic lamp
150
when the hydraulic circuit fails and an ACG lamp
152
when the AC generator fails. Together with lighting these lamps it sounds a buzzer
154
. Explanation will not be made with regard to other components appearing in
FIG. 4
that are not directly related to the substance of this invention.
The operation of the illustrated idling speed control system for an outboard motor will now be explained.
FIG. 5
is a main flow chart showing the sequence of operations of the system. The illustrated program is activated once every 40 msec, for example.
In S
10
it is checked whether the detected throttle opening TH is greater than or equal to a predetermined opening THREF (at or near zero). In other words, it is discriminated whether or not the engine
16
is in the idling region. When the result is YES, the program proceeds to S
12
in which the bit of a flag F.FB is reset to zero. Resetting the bit of the flag F.FB to zero indicates that no feedback control of the idling speed (i.e., the engine speed control during idling) is to be conducted.
Next, in S
14
, it is checked whether the detected engine speed NE is greater than a predetermined protective engine speed NEG (e.g., 5000 rpm). When the result is YES, the program proceeds to S
16
in which a current command value IFB (more precisely, the current command value during idling speed feedback control) is set to zero. In this way, the desired amount of supplied secondary air is expressed as a current command value for the EACV
74
. Since secondary air is therefore supplied to the cylinder combustion chambers in an amount proportional to the current command value, the quantity of fuel injection is increased/reduced proportionally to increase/reduce the engine speed (rpm). More specifically, the inflow of secondary air changes the pressure in the intake pipe in the same way that opening/closing the throttle does and, therefore, the quantity of fuel injection and the engine speed are increased/decreased in proportion.
When the result in S
10
is NO and it is found that the engine
16
is in the idling region, the program proceeds to S
18
in which it is checked whether the bit of a flag F.NA is reset to zero. The setting/resetting of the bit of the flag F.NA is conducted by a separate routine (not shown in the drawings), which resets the bit to zero when the detected engine speed NE is at or below feedback execution speed NA (e.g., 1000 rpm).
FIG. 6
is a graph for explaining the characteristic of the feedback execution speed NA. The feedback execution speed NA is set lower than the predetermined engine speed NEG and defined so as to increase in proportion to the desired idling speed (hereinafter referred to as desired idling speed NOBJ), which will be explained later.
When the result in S
18
is NO, i.e., when the detected engine speed NE is found to be relatively high, in other words, when the engine
16
is decelerating, the program proceeds to S
20
in which the bit of the flag F.FB is reset to zero, and to S
22
in which the current command value IFB is set to zero. When the result in S
18
is YES, i.e., when the engine speed NE is found to be relatively low, the program proceeds to S
24
in which the bit of the flag F.FB is set to 1. The setting of the bit of the flag to 1 indicates that feedback control is to be executed. Next, in S
26
, the current command value IFB is calculated. It is also calculated when the result in S
14
is NO, more specifically, when the engine
16
is accelerating at a speed not more than NEG or the engine
16
is under steady state.
FIGS. 7 and 8
show a subroutine flow chart of the sequence of operations for calculating the current command value IFB in S
26
of the flow chart of FIG.
6
.
In S
100
, correction coefficients KP, KI and KD are calculated. The program then proceeds to S
102
in which an excessive change correction value IUP is set to zero.
Next, in S
104
, it is determined whether the engine
16
was in start mode in the preceding control cycle, i.e., during the preceding program loop of the flow chart of FIG.
5
. This is determined by checking whether the detected engine speed NE had reached full-firing speed. When the result in S
104
is YES, the program proceeds to S
106
in which a base current command value IAI is set to a predetermined engine start time value ICRST.
When the result in S
104
is NO, the program proceeds to S
108
in which it is checked whether the bit of the flag F.FB is set to 1. When the result is YES, the program proceeds to S
110
in which it is checked whether the bit of the flag F.FB was also 1 in the preceding control cycle. When the bit was first set to 1 in the present (current) control cycle (program loop), the result in S
110
is NO and the program proceeds to S
112
in which it is checked whether the bit of the flag F.NA is 0.
When the result in S
112
is YES, the detected engine speed NE is below the feedback execution speed NA and the program therefore proceeds to S
114
in which the excessive change correction value IUP0 is determined by retrieval from an IUP0 table (whose characteristic is not shown) using the intake air temperature TA as the address. S
114
is skipped when the result in S
112
is NO.
When the result in S
110
is YES, meaning that feedback control was also executed in the preceding control cycle, the program proceeds to S
116
in which the preceding current command value IFB(k−1) is latched, and to S
118
in which it is checked whether the output of the neutral switch
34
(illustrated as “NTSW” in the figure) reversed, i.e., whether the shift lever
32
was shifted from Neutral to Forward (or Reverse) or from Forward (or Reverse) to Neutral. When the result in S
118
is YES, the program proceeds to S
120
in which it is checked whether a shift was made from Neutral to an IN GEAR (geared) state, i.e., from Neutral to Forward (or Reverse).
When the result in S
120
is YES, the program proceeds to S
122
in which the excessive change correction value IUP
1
is retrieved from an IUP
1
table (whose characteristic is not shown) using the detected intake air temperature TA as an address. When the result in S
120
is NO, the program proceeds to S
124
in which the excessive change correction value IUP
2
is retrieved from an IUP
2
table (whose characteristic is not shown) using the intake air temperature TA as an address. The excessive change correction values of the tables IUPn are defined such that IUP
0
>IUP
1
>IUP
2
.
This is because IUP
0
, IUP
1
, and IUP
2
are respectively tables from which the excessive change correction value IUP is retrieved when the engine speed is on the decline, during load, and during no load. The values of the IUP
0
table must therefore be defined large to bring the engine speed NE back up to the proper level and the values of the IUP
1
table need to be set larger than those of the IUP
2
table.
Next, in S
126
, it is checked whether the bit of a flag F.AST is set to 1. The bit of this flag is set to 1 in a separate routine (not shown) in the post-start state of the engine
16
. The “post-start state” of the engine
16
is defined as that when the detected engine speed NE has reached the full-firing speed (500 rpm).
When the result in S
126
is NO, the program proceeds to S
126
in which it is checked whether the shift lever
32
is in the IN GEAR state, i.e., whether it has been put in Forward (or Reverse). When the result is NO, the program proceeds to S
130
in which the sum of a correction value IAST and an idling learning control value (desired amount of secondary air required during idling) AXREF (explained later) is defined as the base value of the preceding control cycle IAI(k−1).
When the result in S
128
is YES, the program proceeds to S
132
in which the sum of the correction value (air amount required immediately after start) IAST and a trolling learning control value (desired amount of secondary air required during trolling) TXREF (explained later) is defined as the base value of the preceding control cycle LAI(k−1).
As termed in this specification and the drawings, “trolling” means moving of the boat
12
forward or backward with the shift lever
32
put in Forward (or Rearward) and the throttle at full closed. In other words, it means moving of the boat
12
forward or backward at very low speed with the engine
16
in the idling state.
As used in this specification and the drawings, the suffix k indicates sampling time in discrete-time series, particularly program loop time in the flow chart of FIG.
5
. Still more specifically, a value suffixed with (k) is that during the present control cycle and a value suffixed with (k−1) is that during the preceding control cycle. For simplicity, the suffix (k) is omitted except when necessary to avoid confusion.
When the result in S
126
is YES, the program proceeds to S
134
in which it is checked whether the shift lever
32
is in the IN GEAR state, i.e., whether it has been put in Forward (or Reverse). When the result in S
134
is NO, the program proceeds to S
136
in which the sum of a coolant correction value ITW, the idling learning control value (desired amount of secondary air required during idling) AXREF (explained later) and the excessive change correction value IUP is defined as the base value of the preceding control cycle IAI(k−1).
When the result in S
134
is YES, the program proceeds to S
138
in which the sum of the coolant correction value ITW, the trolling learning control value (desired amount of secondary air required during trolling) TXREF (explained later) and the excessive change correction value IUP is defined as the base value of the preceding control cycle IAI(k−1).
The idling learning control value (desired amount of secondary air required during idling) AXREF and trolling learning control value (desired amount of secondary air required during trolling) TXREF are assigned the generic symbol IXREF. Calculation of the learning control values is explained later.
When the result in S
108
is NO, such as when the program passes from S
14
to S
26
in the flow chart of
FIG. 5
, the program proceeds to S
140
in which it is checked whether the bit of the flag F.FB was set to
1
in the preceding control cycle. When the result in S
140
is YES, i.e., when the bit of the flag F.FB has not been reset to 0 continuously but only in the present control cycle, the program proceeds to S
126
. When the result in S
140
is NO, the program proceeds to S
142
in which it is checked whether the bit of the flag F.AST was 0 in the preceding control cycle and changed to 1 in the present control cycle. When the result in S
140
is YES, the program proceeds to S
134
.
The program next proceeds to S
144
in which the difference or deviation-DNOBJ between the detected engine speed NE and the desired idling speed NOBJ (explained later) is calculated and multiplied by the aforesaid correction coefficients to obtain a proportional correction value IP, integral correction value II and derivative correction value ID. The same applies when the processing of S
106
has been carried out and when the result in S
142
is NO.
Next, in S
146
, the calculated integral correction value II is added to the base current command value of the preceding control cycle IAI(k−1) to obtain the base current command value in the present control cycle IAI(k). Next, in S
148
(FIG.
8
), limit values ILMT, more specifically a lower limit value ILML and an upper limit value ILMH, are retrieved. Next, in S
150
, it is checked whether the calculated base current command value IAI(k) is greater than or equal the retrieved lower limit value ILML. When the result is YES, the program proceeds to S
152
in which it is checked whether the calculated base current command value IAI(k) is less than or equal to the retrieved upper limit value ILMH.
When the result in S
152
is YES, the program proceeds to S
154
in which the proportional correction value IP and the derivative correction value ID are added to the calculated base current command value IAI(k) and the sum obtained is defined as the current command value IFB.
The explanation of the flow chart of
FIG. 8
will be interrupted at this point to explain this control with reference to the time chart of FIG.
9
.
As shown at (a) in FIG.
9
and as was pointed out earlier, when the shift lever
32
is shifted from Neutral to Forward (or reverse), the engine speed NE falls, for instance, from 750 rpm to 650 rpm. In the conventional system, the abrupt change in engine speed this produces the aforesaid overshooting or undershooting of engine speed and causes the operator to experience an unpleasant feeling.
In this embodiment, therefore, learning control values are utilized and, as shown (b) in the same figure, the learning control value is changed according to the shift position. Therefore, as shown at (a) in the figure, the engine speed NE can be smoothly varied and stable low-speed operation can be achieved during trolling. As shown at (d), in this embodiment, the desired idling speed NOBJ is varied in response to the position of clutch (shift), which will be explained later.
In addition, as shown at (c) in the figure, when the engine speed is likely to change sharply, to be more specific, when the difference between the current command values IFB in the preceding control cycle and the present control cycle becomes large, the current command value IFB (i.e., the amount of secondary air) is decreased or increased such that the engine speed NE converges to the desired speed gradually or stepwise so as to suppress the overshooting or undershooting of engine speed. With this, it becomes possible to eliminate or reduce due to the clutch change (shift change) and to improve the feeling experienced by the operator.
Returning to the explanation of the flow chart of
FIG. 8
, the program proceeds to S
156
in which it is determined whether the bit of the flag FB is set to 1 and if YES, proceeds to S
158
in which it is determined whether the bit of the flag F.FB was 1 in the preceding control cycle (program loop).
When the result in S
158
is YES, the program proceeds to S
160
in which it is determined whether the bit of a flag F.NTSW (explained later) is set to 1. When the result is NO, the program proceeds to S
162
in which it is determined whether the output of the neutral switch
34
reversed and when the result is YES, the program proceeds to S
164
in which the bit of the flag F.NTSW is set to 1. Thus, the flag F.NTSW is a latch flag which indicates whether the output of the neutral switch
34
reversed, and the bit is set to 1 each time the switch output reverse irrespectively of the direction (i.e., from Neutral to the IN GEAR state (Forward or Reverse) or vice versa). When the result in S
160
is YES, the program skips S
162
and S
164
.
Then the program proceeds to S
166
in which it is determined whether the absolute value of the difference obtained by subtracting the current command value in the preceding control cycle IFB(k−1) from the calculated current command value in this control cycle IFB, is greater than a predetermined value #DIFB, in other words, it is determined whether the difference is large.
The predetermined value #DIFB is set to be varied with the load exerted on the engine
16
. More specifically, #DIFB is set to be increased with increasing load and is replaced with (changed by) the calculated learning control value IXREF, the detected absolute manifold pressure PBA, etc. With this, it becomes possible to take the change of the amount of secondary air due to the fluctuation of load into account and to make the transient time from the idling speed to the trolling speed (and vice versa) constant. This can improve the feeling experienced by the operator.
When the result in S
166
is YES, the program proceeds to S
168
in which it is determined whether the difference between the present value and the preceding value is greater than or equal to zero, in other words, it is determined whether it is on the increase (i.e., it changes in the increasing direction).
When the result in S
168
is negative, the program proceeds to S
170
in which the value obtained by subtracting a predetermined value DIFBHEX1 from the current command value of the preceding control cycle IFB(k−1) is defined as IFB. When the result in S
168
is YES, the program proceeds to S
172
in which the value obtained by adding a predetermined value DIFBHEX2 to the current command value of the preceding control cycle IFB(k−1) is defined as IFB.
As illustrated in
FIG. 10
, the values #DIFBHEX1 for subtraction and #DIFBHEX2 for addition are set relative to the engine coolant temperature TW. To be more specific, since the control response improves as the temperature increases, the values are set to be finer or smaller with increasing temperature. With this, it becomes possible to conduct finer control until the engine speed reaches the desired speed at a high engine coolant temperature. Accordingly, it becomes possible to switch the engine speed from the idling to trolling (and vice versa) in a smoother manner and to give a better feeling to the operator.
Further, as illustrated in the figure, since the value DIFBHEX1 for subtraction is set to be larger than the value DIFBHEX2 for addition, it becomes possible to bring the engine speed to the trolling speed promptly when the clutch is shifted to the trolling position (Forward or Reverse), and to achieve a finer and smoother transitional speed to the idling speed when the clutch is shifted back to Neutral. With this, it becomes to further improve the feeling experienced by the operator. When the clutch is returned to Neutral, since more time is permitted than the case where the clutch is shifted in the trolling direction, no problem will occur when stages to return to the idling speed is made finer, i.e., when a time to return to the idling speed is prolonged.
Returning to the explanation of the flow chart of
FIG. 8
, when the result in S
166
is NO, the program proceeds to S
174
in which the bit of the flag F.NTSW is reset to 0.
Then the program proceeds to S
176
in which it is determined whether the calculated current command value IFB is greater than or equal to the lower limit value ILML. This is the same when the result is NO in S
156
, S
158
, S
160
and S
162
. When the result in S
176
is YES, the program proceeds to S
178
in which it is determined whether the calculated current command value IFB is less than or equal to the upper limit value ILMH. When the result is YES, the program proceeds to S
180
in which the calculated current command of the present control cycle IFB is renamed that in the preceding control cycle IFB(k−1)
When the result in S
150
is NO, the program proceeds to S
182
in which the retrieved lower limit value ILML is defined as the base current command value of the present control cycle IAI(k). When the result in S
176
is NO, the program proceeds to S
184
in which the based current command value of the preceding control cycle IAI(k−1) is replaced with that of the present control cycle IAI(K) and proceeds to S
186
in which the lower limit value ILML is defined as the current command value IFB.
When the result in S
152
is NO, the program proceeds to S
188
in which the retrieved upper limit value ILMH is defined as the base current command value of the present control cycle IAI(k). When the result in S
178
is NO, the program proceeds to S
190
in which the based current command value of the preceding control cycle IAI(k−1) is renamed that of the present control cycle IAI(k) and proceeds to S
192
in which the upper limit value ILMH is defined as the current command value IFB.
The program next proceeds to S
194
in which the learning control value IXREF is calculated. As was mentioned earlier, IXREF is a generic symbol for the idling learning control value AXREF and trolling learning control value TXREF.
FIG. 11
is subroutine flow chart showing the sequence of operations for calculating the learning control value IXREF.
In S
200
, it is checked whether the bit of the flag F.FB is set to 1, i.e., whether the system is in feedback mode. When the result is NO, the remaining steps in the subroutine are skipped.
Next, in S
202
, it is checked whether the bit of the flag F.AST is set to 1, i.e., whether the system is in post-start mode. When the result is NO, the remaining steps are skipped. When the result is YES, the program proceeds to S
204
in which it is checked whether the voltage VACG at the F terminal
134
of the AC generator is less than or equal to a predetermined value VACGREF. When the result is NO, the remaining steps are skipped.
When the result in S
204
is YES, the program proceeds to S
206
in which it is checked whether the detected manifold absolute pressure PBA in the air intake pipe is less than or equal to a predetermined value PBAIX. When the result is NO, the remaining steps are skipped. When the result is YES, the program proceeds to S
208
in which it is checked whether the detected manifold absolute pressure PBA in the air intake pipe is greater than or equal to a prescribe value DPBAX. When the result is NO, the remaining steps are skipped.
When the result in S
208
is YES, the program proceeds to S
210
in which the variation value DNECYCL of the detected engine speed NE during a predetermined combustion cycle (e.g., the first combustion cycle) is calculated as an absolute value and checked as to whether it is less than or equal to a predetermined value DNEG. When the result is NO, the remaining steps are skipped. When the result is YES, the program proceeds to S
212
in which the variation value DNOBJ of the desired idling speed NOBJ is calculated as an absolute value and checked as to whether it is less than a predetermined value DNX. When the result is NO, the remaining steps are skipped.
When the result in S
212
is YES, the program proceeds to S
214
in which it is checked whether the detected engine coolant temperature TW is greater than or equal to a predetermined value TWX1. When the result is NO, the remaining steps are skipped. When the result is YES, the program proceeds to S
216
in which, by referring to a suitable flag in a separate air-fuel ratio control routine (not shown), for example, it is checked whether the system is in an air-fuel ratio feedback region based on the outputs of the O2 sensors
110
. When the result is YES, the program proceeds to S
218
in which it is checked by a similar method whether air-fuel ratio feedback control is in effect. When the result in S
216
is NO, S
218
is skipped.
When the result in S
218
is NO, the remaining steps are skipped. When it is YES, the program proceeds to S
220
in which the learning control values IXREF are calculated.
FIG. 12
is a subroutine flow chart showing the sequence of operations for this calculation.
In S
300
, it is checked whether the bit of the flag F.AST is set to 1, i.e., whether the system is in post-start mode. When the result is NO, the remaining steps are skipped. When the result in S
300
is YES, the program proceeds to S
302
in which it is checked whether the detected engine coolant temperature TW is greater than or equal to a predetermined value TWXC.
When the result in S
302
is YES, meaning that the coolant temperature is high, the program proceeds to S
304
in which it is checked whether the detected manifold absolute pressure PBA in the air intake pipe is less than or equal to a predetermined value PBAXC. When the result is YES, meaning that the load is low, the program proceeds to S
306
in which the detected engine coolant temperature TW and the manifold absolute pressure PBA in the air intake pipe are used as address data for retrieving from a table, whose characteristic is shown in
FIG. 13
, a value CXREF0A that is defined as a smoothing coefficient CXREF.
When the result in S
304
is NO, meaning the load is high, the program proceeds to S
308
in which, similarly, the detected engine coolant temperature TW and the absolute pressure PBA in the air intake pipe are used as address data for retrieving from the table whose characteristic is shown in
FIG. 13
a value CXREF0B that is defined as the smoothing coefficient CXREF.
When the result in S
302
is NO, meaning that the coolant temperature is low, the program proceeds to S
310
in which, similarly, the detected engine coolant temperature TW and the manifold absolute pressure PBA in the air intake pipe are used as address data for retrieving from the table whose characteristic is shown in
FIG. 13
a value CXREF1 that is defined as the smoothing coefficient CXREF.
Next, in S
312
, the calculated smoothing coefficient and the base value etc. mentioned earlier are used to calculate the post-engine-start idling learning control value AXREF in accordance with the formula shown. The learning control value is thus calculated so as to smooth or temper the base current command value IAI (more specifically, the difference between it and the coolant correction value ITW) calculated for eliminating deviation between the desired idling speed NOBJ and the detected engine speed NE. In other words, the learning control value is calculated so that the desired amount of secondary air (required air amount) produces the desired idling speed NOBJ.
Next, in S
314
, it is checked whether the shift lever
32
is shifted to Neutral or to Forward (or Reverse). When it is found to be shifted to Neutral, the processing operations of S
316
to S
324
are carried out to calculate the smoothing coefficient CXREF by retrieval from the table whose characteristic is similar to that shown in FIG.
13
. The program then proceeds to S
326
in which the post-engine-start idling learning control value AXREF is similarly calculated. When the shift lever
32
is found to be shifted to Forward (or Reverse) in S
314
, the processing operations of S
328
to S
336
are carried out to calculate the smoothing coefficient CXREF by retrieval from the table whose characteristic is similar to that shown in FIG.
13
.
The program then proceeds to S
338
in which the post-engine-start trolling learning control value TXREF is similarly calculated. The learning control values AXREF and TXREF calculated in the foregoing manner are stored in the EEPROM
22
a,
where they are retained even after the engine
16
has been stopped.
The explanation of the flow chart of
FIG. 11
will be continued. Next, in S
222
, the calculated learning control value is subjected to a limit check.
FIG. 14
is a subroutine flow chart showing the sequence of operations for this purpose.
In S
400
, it is checked whether the shift lever
32
is in Neutral or in Forward (or Reverse). When it found to be in Neutral, the program proceeds to S
402
in which it is checked whether the calculated idling learning control value AXREF is less than a predetermined lower limit value #IXREFGL. When the result is YES, the program proceeds to S
404
in which the lower limit value #IXREFGH is defined as the learning control value.
When the result in S
402
is NO, the program proceeds to S
406
in which it is checked whether the calculated idling learning control value AXREF is greater than an upper limit value #IXREFGH. When the result is YES, the program proceeds to S
408
in which the upper limit value #IXREFGH is defined as the learning control value. When the result is NO, S
408
is skipped.
When the result in S
400
is the IN GEAR state, i.e., when it is found that the shift lever
32
is shifted to Forward (or Reverse), the program proceeds to S
410
in which it is checked whether the calculated trolling learning control value TXREF is less than a lower limit value #TXREFGL. When the result is YES, the program proceeds to S
412
in which the lower limit value #TXREFGL is defined as the learning control value.
When the result in S
410
is NO, the program proceeds to S
414
in which it is checked whether the calculated trolling learning control value TXREF is greater than an upper limit value #TXREFGH. When the result is YES, the program proceeds to S
416
in which the upper limit value #TXREFGH is defined as the learning control value. When the result in S
414
is NO, S
416
is skipped.
The calculation of the desired idling speed NOBJ will now be explained.
FIG. 15
is a subroutine flow chart showing the sequence of operations for this calculation.
In S
500
, it is checked whether the bit of the flag F.AST is set to 1. When the result is NO, meaning that the engine is in start mode, the program proceeds to S
502
in which it is checked whether the neutral switch
34
is outputting an ON signal, i.e., whether the shift lever
32
is shifted to Neutral. When the result in S
502
is YES and the shift lever
32
is found to be shifted to Neutral, the program proceeds to S
504
in which the desired idling speed NOBJ is calculated by retrieval from a table (characteristic) representing NOBJ0 in
FIG. 16
using the detected engine coolant temperature TW and engine speed NE as address data.
When the result in S
502
is NO and the shift lever
32
is found to be shifted to Forward (or Reverse), the program proceeds to S
506
in which the desired idling speed NOBJ is calculated by retrieval from a table (characteristic) representing NOBJ1 in
FIG. 16
using the detected engine coolant temperature TW and engine speed NE as address data.
When the result in S
500
is YES, meaning that the engine is in start mode, the program proceeds to S
508
in which it is checked whether the neutral switch
34
is outputting an ON signal. When the result is YES, the program proceeds to S
510
in which the desired idling speed NOBJ is calculated by retrieval from a table (characteristic) NOBJ3 like the table representing NOBJ0 in
FIG. 16
using the detected engine coolant temperature TW and engine speed NE as address data.
When the result in S
508
is NO and the shift lever
32
is found to be shifted to Forward (or Reverse), the program proceeds to S
512
in which the desired idling (trolling) speed NOBJ is calculated by retrieval from a table (characteristic) NOBJ4 like the table representing NOBJ1 in
FIG. 16
using the detected engine coolant temperature TW and engine speed NE as address data.
Having been configured in the foregoing manner, in this embodiment, when the engine speed NE is likely to change abruptly, in other words, when the difference between the preceding and present current command values IFB is large, the current command value IFB is increased or decreased by the predetermined value DIFBHEX1, 2 such that the engine speed is changed to the desired speed gradually or stepwise. With this, it becomes possible to suppress the occurrence of the overshooting or undershooting of engine speed due to the load change and to eliminate or reduce the shock experienced by the operator of the outboard in such a way that he or she can have an improved feeling.
Further, if the operator should replace the propeller which results in the load change, since the predetermined value #DIFB is set to be increased with increasing load, it becomes possible to take the change of the amount of secondary air due to the fluctuation of load into account and to make the transient time from the idling speed to the trolling speed (and vice versa) constant. This can improve the feeling experienced by the operator.
Further, the values #DIFBHEX1 for subtraction and #DIFBHEX2 for addition are predetermined relative to the engine coolant temperature TW. To be more specific, since the control response improves as the temperature increases, the values are set to be finer or smaller with increasing temperature. With this, it becomes possible to conduct finer control until the engine speed reaches the desired speed at a high engine coolant temperature. Accordingly, it becomes possible to switch the engine speed from the idling to trolling (and vice versa) in a smoother manner and to give a better feeling to the operator.
Further, since the value DIFBHEX1 for subtraction is set to be larger than the value DIFBHEX2 for addition, it becomes possible to bring the engine speed to the trolling speed promptly when the clutch is shifted to the trolling position (Forward or Reverse), and to achieve a finer and smoother transitional speed to the idling speed when the clutch is shifted back to Neutral. With this, it becomes to further improve the feeling experienced by the operator. When the clutch is returned to Neutral, since more time is permitted than the case where the clutch is shifted in the trolling direction, no problem will occur when stages to return to the idling speed is made finer, i.e., when a time to return to the idling speed is prolonged.
Further, the desired idling (or trolling) speed NOBJ is changed according to the shift (clutch) position in the start-state of the engine
16
and as shown in FIG.
9
(
d
). As a result, the desired idling (or trolling) speed can be reliably determined in accordance with the engine operating condition and the shift position.
Furthermore, since the system controls the amount of secondary air (required air amount) so as to achieve the determined desired (trolling) idling speed, accurate control can be effected to achieve steady idling (trolling) speed. In addition, since the system can achieve a lower engine speed than the conventional system during trolling and the like, it is capable of enhancing fuel performance.
The embodiment is thus configured to have a system for controlling an idling speed for an outboard motor mounted on a boat
12
and equipped with an internal combustion engine
16
whose output is connected to a propeller
40
through a clutch
36
such that the boat is propelled forward or reverse when the clutch is changed to a neutral (Neutral) position to a forward (Forward) position or a reverse (Reverse) position, comprising a secondary air supplier
80
that supplies secondary air trough a passage (branch passage
72
) that is connected to an air intake pipe
46
downstream of a throttle valve
50
and that is equipped with a secondary air control valve (EACV
74
) such that amount of secondary air is supplied to the air intake pipe in response to an opening of the secondary air control valve; clutch position detecting means (neutral switch (NTSW)
34
, ECU
22
, S
118
, S
162
) for detecting a position of the clutch; engine operating condition detecting means (crank angle sensor
124
, manifold absolute pressure sensor
94
, intake air temperature sensor
100
, coolant temperature sensor
106
, ECU
22
) for detecting parameters indicative of operating conditions of the engine including at least an engine speed NE; desired value determining means (ECU
22
) for determining a desired idling speed based on the detected position of the clutch and for determining a desired secondary air supply amount (i.e., current command value IFB indicative of the amount of secondary air) such that a difference between the determined desired idling speed and the detected engine speed decreases; and valve controlling means (ECU
22
) for controlling the opening of the valve to a value that effects the desired secondary air supply amount; wherein the desired value determining means including: comparing means (ECU
22
, S
162
, S
166
) for calculating a change of the desired secondary air supply amount and for comparing the change with a predetermined value #difb when it is determined based on the detected position of the clutch that the clutch is changed; change direction determining means (ECU
22
, S
168
) for determining whether the change is in an increasing direction or in a decreasing direction; and correcting means (ECU
22
, S
170
, S
172
) for correcting the desired secondary air supply amount by a predetermined correction amount DIFBHEX 1,2 in the determined direction, when the change is greater than the predetermined value.
In the system, the predetermined value is set with respect to a load exerted on the engine. More specifically, the predetermined value is set to be increased with increasing load.
In the system, the predetermined correction amount is set with respect to a coolant temperature TW of the engine. More specifically, the predetermined correction amount is set to be decreased with increasing temperature.
In the system, the predetermined correction amount DIFBHEX 1, 2 is set to be different for different directions, and the predetermined correction amount in the decreasing direction is set to be greater than that in the increasing direction.
In the system, the comparing means calculates a change of the desired secondary air supply amount in an absolute value between the amount of a preceding control cycle and that of a present cycle.
In the system, the desired value determining means learning-controls the determined desired secondary air supply amount (ECU
22
, S
300
to S
338
).
In the system, the desired value determining means learning-controls the determined desired secondary air supply amount such that the difference between the desired idling speed and the detected engine speed decreases (ECU
22
, S
300
to S
338
).
In the system, the desired value determining means determines the desired secondary air supply amount in terms of current command value IFB to operate the secondary air control valve (EACV
74
).
It should be noted that, although the invention has been explained with reference to an embodiment of an outboard motor, the invention is not limited in application to an outboard motor but can also be applied to an inboard motor.
It should also be noted that, although the invention has been explained with reference to an embodiment equipped not only with a secondary air supplier but also with a DBW (Drive-by-Wire) system for driving the throttle valve with an actuator, the DBW system is not an essential feature of the invention.
The entire disclosure of Japanese Patent Application No. 2000-400349 filed on Dec. 28, 2000, including specification, claims, drawings and summary, is incorporated herein in reference in its entirety.
While the invention has thus been shown and described with reference to specific embodiments, it should be noted that the invention is in no way limited to the details of the described arrangements but changes and modifications may be made without departing from the scope of the appended claims.
Claims
- 1. A system for controlling an idling speed for an outboard motor mounted on a boat and equipped with an internal combustion engine whose output is connected to a propeller through a clutch such that the boat is propelled forward or reverse when the clutch is changed to a neutral position to a forward position or a reverse position, comprising:a secondary air supplier that supplies secondary air through a passage that is connected to an air intake pipe downstream of a throttle valve and that is equipped with a secondary air control valve such that an amount of secondary air is supplied to the air intake pipe in response to an opening of the secondary air control valve; clutch position detecting means for detecting whether or not the clutch is at a neutral position; engine operating condition detecting means for detecting parameters indicative of operating conditions of the engine including at least an engine speed; desired value determining means for determining a desired idling speed based on whether or not the detected position of the clutch is at the neutral position and for determining a desired secondary air supply amount such that a difference between the determined desired idling speed and the detected engine speed decreases; and valve controlling means for controlling the opening of the valve to a value that effects the desired secondary air supply amount; wherein the desired value determining means includes: comparing means for calculating a change of the desired secondary air supply amount and for comparing the change with a predetermined value when it is determined based on the detected position of the clutch that the clutch is changed; change direction determining means for determining whether the change of the desired secondary air supply amount is in an increasing direction or in a decreasing direction; and correcting means for correcting the desired secondary air supply amount by a predetermined correction amount in the determined direction, when the change is greater than the predetermined value.
- 2. A system according to claim 1, wherein the predetermined value is set with respect to a load exerted on the engine.
- 3. A system according to claim 2, wherein the predetermined value is set to be increased with increasing load.
- 4. A system according to claim 1, wherein the predetermined correction amount is set with respect to a coolant temperature of the engine.
- 5. A system according to claim 4, wherein the predetermined correction amount is set to be decreased with increasing temperature.
- 6. A system according to claim 5, wherein the predetermined correction amount is set to be different for different directions.
- 7. A system according to claim 6, wherein the predetermined correction amount in the decreasing direction is set to be greater than that in the increasing direction.
- 8. A system according to claim 1, wherein the comparing means calculates a change of the desired secondary air supply amount in an absolute value between the amount of a preceding control cycle and that of a present cycle.
- 9. A system according to claim 1, wherein the desired value determining means learning-controls the determined desired secondary air supply amount.
- 10. A system according to claim 9, wherein the desired value determining means learning-controls the determined desired secondary air supply amount such that the difference between the desired idling speed and the detected engine speed decreases.
- 11. A system according to claim 1, wherein the desired value determining means determines the desired secondary air supply amount in terms of current command value to operate the secondary air control valve.
- 12. A method of controlling an idling speed for an outboard motor mounted on a boat and equipped with an internal combustion engine whose output is connected to a propeller through a clutch such that the boat is propelled forward or reverse when the clutch is changed to a neutral position to a forward position or a reverse position, having a secondary air supplier that supplies secondary air through a passage that is connected to an air intake pipe downstream of a throttle valve and that is equipped with a secondary air control valve such that amount of secondary air is supplied to the air intake pipe in response to an opening of the secondary air control valve, comprising the steps of(a) detecting whether or not the clutch is at a neutral position; (b) detecting parameters indicative of operating conditions of the engine including at least an engine speed; (c) determining a desired idling speed based on whether or not the detected position of the clutch is the neutral position and for determining a desired secondary air supply amount such that a difference between the determined desired idling speed and the detected engine speed decreases; and (d) controlling the opening of the valve to a value that effects the desired secondary air supply amount; wherein the step (c) including the steps of: (e) calculating a change of the desired secondary air supply amount and comparing the change with a predetermined value when it is determined based on the detected position of the clutch that the clutch is changed; (f) determining whether the change of the desired secondary air supply amount is in an increasing direction or in a decreasing direction; and (g) correcting the desired secondary air supply amount by a predetermined correction amount in the determined direction, when the change is greater than the predetermined value.
- 13. A method according to claim 12, wherein the predetermined value is set with respect to a load exerted on the engine.
- 14. A method according to claim 13, wherein the predetermined value is set to be increased with increasing load.
- 15. A method according to claim 12, wherein the predetermined correction amount is set with respect to a coolant temperature of the engine.
- 16. A method according to claim 15, wherein the predetermined correction amount is set to be decreased with increasing temperature.
- 17. A method according to claim 16, wherein the predetermined correction amount is set to be different for different directions.
- 18. A method according to claim 17, wherein the predetermined correction amount in the decreasing direction is set to be greater than that in the increasing direction.
- 19. A method according to claim 12, wherein the step (e) calculates a change of the desired secondary air supply amount in an absolute value between the amount of a preceding control cycle and that of a present cycle.
- 20. A method according to claim 12, wherein the step (c) learning-controls the determined desired secondary air supply amount.
- 21. A method according to claim 20, wherein the step (c) learning-controls the determined desired secondary air supply amount such that the difference between the desired idling speed and the detected engine speed decreases.
- 22. A method according to claim 12, wherein the step (c) determines the desired secondary air supply amount in terms of current command value to operate the secondary air control valve.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-400349 |
Dec 2000 |
JP |
|
US Referenced Citations (22)