Title: Fuel injection control system for internal combustion engine
Abstract: A fuel injection control system for an internal combustion engine can obtain an optimum fuel injection quantity in response to a traveling load without the need for a large memory. The gear position discrimination unit determines the present gear position Ngp on the basis of the vehicle speed Vpls and the engine speed NE. The Kgpd calculation unit calculates the correction factor by gear Kgpd on the basis of the gear position Ngp and the engine speed NE. The state judgment unit judges whether the engine is in a steady state or in a transient state. The map selection unit selects, on the basis of the judgment result of the engine state, the PB map or the TH map for determining the basic injection quantity Ti. The basic injection quantity determination unit determines the basic injection quantity Ti on the basis of a product of the PB map or TH map and the correction factor by gear Kgpd.
Patent Number: 7,011,604 Issued on 03/14/2006 to Watanabe, et al.
| Inventors:
|
Watanabe; Tsuguo (Saitama, JP);
Abe; Masahiko (Saitama, JP);
Hayashi; Tatsuo (Saitama, JP);
Yuhara; Tomomi (Saitama, JP)
|
| Assignee:
|
Honda Giken Kogyo Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
645612 |
| Filed:
|
August 22, 2003 |
Foreign Application Priority Data
| Sep 10, 2002[JP] | 2002-264176 |
| Current U.S. Class: |
477/110; 477/107; 701/54; 701/61 |
| Current Intern'l Class: |
B60K 41/04 (20060101) |
| Field of Search: |
477/107,110
123/332,349
701/54,61
|
References Cited [Referenced By]
U.S. Patent Documents
| 3763720 | Oct., 1973 | Aono et al.
| |
| 4976239 | Dec., 1990 | Hosaka.
| |
| 5019799 | May., 1991 | Oshiage et al.
| |
| 5230318 | Jul., 1993 | Iwamoto.
| |
| 6240534 | May., 2001 | Nakane.
| |
| 6269289 | Jul., 2001 | Toukura et al.
| |
| 6301529 | Oct., 2001 | Itoyama et al.
| |
| 6442471 | Aug., 2002 | Bosse.
| |
| 2002/0010539 | Jan., 2002 | Machida et al.
| |
| 2002/0107107 | Aug., 2002 | Ogawa et al.
| |
| Foreign Patent Documents |
| 100 14 218 | Oct., 2001 | DE.
| |
| 2000-18063 | Jan., 2000 | JP.
| |
Primary Examiner: Ho; Ha
Attorney, Agent or Firm: Birch, Stewart, Kolasch & Birch, LLP
Claims
What is claimed is:
1. A fuel injection control system for an internal combustion engine, the engine
for transmitting a driving force to an output shaft through a transmission, comprising:
means for detecting engine speed NE;
means for detecting a throttle opening θTH;
a TH map in which a fuel injection quantity has been registered with the engine
speed NE and the throttle opening θTH as parameters, the TH map being used
to determine a basic fuel injection quantity as a function of the engine speed
NE and the throttle opening θTH;
means for discriminating a gear position of said transmission;
means for determining a fuel injection correction factor on the basis of the
gear position and the engine speed NE; and
means for correcting the basic fuel injection quantity determined by the TH map
on the basis of a gear correction factor.
2. The fuel injection control system for an internal combustion engine according
to claim 1, wherein the lower the gear position becomes, the more said correction
means reduces the fuel injection quantity.
3. The fuel injection control system for an internal combustion engine according
to claim 1, wherein said means for discriminating the gear position discriminates
the gear position on the basis of said engine speed NE and a vehicle speed Vpls.
4. The fuel injection control system for an internal combustion engine according
to claim 1, further comprising means for detecting manifold air pressure PB, wherein
the manifold pressure PB is a factor used to determine the basic fuel injection
quantity along with the engine speed NE and the throttle opening θTH used
by the TH map.
5. The fuel injection control system for an internal combustion engine according
to claim 1, wherein if a rate of change of the throttle opening ΔθTH
exceeds a basic rate of change of the throttle opening ΔθTHref, the
TH map is selected.
6. A fuel injection method for an internal combustion engine, the engine for
transmitting a driving force to an output shaft through a transmission, said method
comprising the steps of:
detecting engine speed NE;
detecting a throttle opening θTH;
providing a TH map in which a fuel injection quantity has been registered with
the engine speed NE and the throttle opening θTH as parameters;
using the TH map to determine a basic fuel iniection guantity as a function of
the engine speed NE and the throttle opening θTH;
discriminating a gear position of said transmission;
determining a fuel injection correction factor on the basis of the gear position
and the engine speed NE; and
correcting the basic fuel injection guantity determined by the TH map on the
basis of a gear correction factor.
7. The method according to claim 6, wherein the lower the gear position becomes,
the more the fuel injection quantity is reduced.
8. The method according to claim 6, wherein said step of discriminating the gear
position further comprises the step of discriminating the gear position on the
basis of said engine speed NE and a vehicle speed Vpls.
9. The method according to claim 6, further comprising the steps of:
detecting manifold air pressure PB; and
using the manifold pressure PB as a factor to determine the basic fuel injection
quantity along with the engine speed NE and the throttle opening θTH used
by the TH map.
10. The method according to claim 6, wherein if a rate of change of the throttle
opening ΔθTH exceeds a basic rate of change of the throttle opening
ΔθTHref, the TH map is selected.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This nonprovisional application claims priority under 35 U.S.C. § 119(a)
on Patent Application No. 2002-264176, filed in Japan on Sep. 10, 2002, the entirety
of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel injection control system for an internal
combustion engine. More particularly, the present invention relates to a fuel injection
control system for correcting a fuel injection quantity on the basis of a gear position.
2. Description of Background Art
A basic injection quantity of fuel is preferably determined on the basis of an
intake air quantity. A technique has been disclosed in which manifold air pressure
capable of accurately representing the intake air quantity has been adopted as
a parameter for determining the basic injection quantity. On the other hand, in
a motorcycle, the response to opening a throttle valve is an important aspect of
operating performance and marketability as a whole. However, a manifold air pressure
sensor does not provide an excellent output response to a change in negative pressure
during transient driving, such as when the throttle is suddenly opened. Accordingly,
it becomes difficult to accurately represent the intake air quantity.
In order to solve such a technical problem, for example, Japanese Patent Laid-Open
No. 4-365943 discloses a technique in which a throttle opening θTH is newly
added as a parameter for determining the basic injection quantity of fuel. The
basic injection quantity is retrieved in a steady state from a manifold air pressure
map (PB map) in which the engine speed NE and the manifold air pressure PB are
used as parameters. In a transient state, the basic injection quantity is retrieved
from a throttle opening map (TH map) in which the engine speed NE and the throttle
opening θTH are used as parameters.
According to the background art technique described above, when an attempt
is made to determine the basic injection quantity on the basis of the TH map, the
basic injection quantity will be uniquely determined if the engine speed NE and
the throttle opening θTH are obtained. However, when the gear position is
low (speed reducing ratio is large) even if the engine speed NE and the throttle
opening θTH are the same, running resistance (engine load) becomes lower
than at a high gear position (speed reducing ratio is small). Therefore, it is
preferable to differentiate the basic injection quantity in accordance with the
gear position. However, if an attempt is made to provide the TH map for each gear
position, there has been a technical problem in that numerous memory areas become necessary.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the problem of the background
art technique described above, and to provide a fuel injection control system for
an internal combustion engine capable of determining an optimum fuel injection
quantity in response to a running load without the necessity of providing a plurality
of throttle opening maps.
In order to achieve the above-described object, the present invention includes
the following means that have been employed in a fuel injection control system
for an internal combustion engine for transmitting a driving force to an output
shaft through a transmission.
(1). The fuel injection control system includes: means for detecting the engine
speed NE; means for determining the fuel injection quantity as a function of the
engine speed NE; means for discriminating the gear position of the transmission;
and means for correcting the fuel injection quantity on the basis of the discrimination
result of the gear position.
(2). The correction means includes means for determining the correction factor
as a function of the gear position, and means for multiplying the fuel injection
quantity by the correction factor.
According to the above-described feature (1), since the fuel injection
quantity is corrected in response to the gear position even if the engine speed
NE and the throttle opening θTH are the same, it becomes possible to always
perform optimum fuel injection.
According to the above-described feature (2), it is possible to obtain
the optimum fuel injection quantity for each gear position without providing a
TH map for each gear position.
Further scope of applicability of the present invention will become apparent
from the detailed description given hereinafter. However, it should be understood
that the detailed description and specific examples, while indicating preferred
embodiments of the invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the invention will become
apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description
given hereinbelow and the accompanying drawings which are given by way of illustration
only, and thus are not limitative of the present invention, and wherein:
FIG. 1 is a general block diagram showing a fuel injection system according
to an embodiment of the present invention;
FIG. 2 is a functional block diagram showing a fuel injection control unit 10
of FIG. 1;
FIG. 3 is a flowchart showing a control procedure of fuel injection;
FIG. 4 is a flowchart showing a discrimination procedure of a gear position;
FIG. 5 is a flowchart showing a calculation procedure of a correction factor
by a gear;
FIG. 6 is a view showing an example of the correction factor by a gear (Kgpd0); and
FIG. 7 is a view showing an example of a throttle correction factor (Kgpth).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, with reference to the accompanying drawings, a description
will be made of a preferred embodiment of the present invention in detail. FIG.
1 is a general block diagram showing a fuel injection control system according
to one embodiment of the present invention. An intake port
22 and an exhaust
port
23 are opened into a combustion chamber
21 of the engine
20.
Each port
22 and
23 is provided with an intake valve
24 and
an exhaust valve
25, respectively. An ignition plug
26 is provided
extending into the combustion chamber
21.
A throttle valve
28 for adjusting the intake air quantity in response
to
the opening θTH thereof, and a throttle sensor
5 for detecting the
throttle opening are provided in an intake passage
27 leading to the intake
port
22. A vacuum sensor
6 for detecting the manifold air pressure
PB and a fuel injection valve
8 are arranged on the downstream side of the
throttle valve
28. An air cleaner
29 is provided at a terminal of
the intake passage
27. An air filter
30 and an intake temperature
sensor
2 for detecting the intake (atmospheric) temperature TA are provided
within the air cleaner
29. Open air is taken into the intake passage
27
through the air filter
30.
An engine speed sensor
4 for detecting engine speed NE on the basis of
a rotation angle of a crankshaft
33 is arranged opposite to the crankshaft
33, which is coupled to a piston
31 of the engine
20 through
a connecting rod
32. Furthermore, a vehicle speed sensor
7 for detecting
vehicle speed Vpls is arranged opposite to a rotor
34, such as a gear, which
is coupled to the crankshaft
33 for rotation. A water temperature sensor
3 for detecting cooling water temperature TW representing the engine temperature
is provided on a water jacket formed around the engine
20.
The ECU (Engine Control Unit)
1 includes a fuel injection control unit
10, a PB map
11, and a TH map
12. In the PB map
11,
a basic injection quantity Ti of fuel has been registered for each corresponding
relationship between the engine speed NE and the manifold air pressure PB. In the
TH map
12, a basic injection quantity Ti of fuel has been registered for
each corresponding relationship between the engine speed NE and the throttle opening θTH.
The fuel injection control unit
10 outputs an injection signal Tout to
the fuel injection valve
8 on the basis of a signal (process value) obtained
by each of the sensors, and the PB map
11 or the TH map
12. This
injection signal Tout is a pulse signal having a pulse width responsive to the
injection quantity. The fuel injection valve
8 is opened by a time period
corresponding to the pulse width to inject the fuel.
FIG. 2 is a functional block diagram for the fuel injection control unit
10.
It should be noted that the same reference numerals have been used to identify
the same or similar elements.
A correction factor calculation unit
101 calculates a manifold air pressure
correction factor Kpb, an intake temperature correction factor Kta and a cooling
water temperature correction factor Ktw and the like on the basis of process values
such as the manifold air pressure PB, the intake temperature TA and the cooling
water temperature TW. The correction factor calculation unit
101 then integrates
all of the correction factors to calculate a total correction factor Ktotal.
A state judgment unit
104 judges whether the engine is in a steady state
or in a transient state on the basis of an hour rate of change ΔθTH
of the throttle opening θTH. A map selection unit
105 selects the
PB map
11 or the TH map
12 as a data map for determining the basic
injection quantity Ti of fuel on the basis of the judgment results of the engine
state. When the TH map
12 is selected by the map selection unit
105,
a gear position judgment unit
102 judges a present gear position Ngp on
the basis of the vehicle speed Vpls and the engine speed NE.
A Kgpd calculation unit
103 calculates a correction factor by a gear Kgpd
on the basis of the discrimination result of the gear position Ngp and the engine
speed NE. A basic injection quantity determination unit
106 determines the
basic injection quantity Ti on the basis of the engine speed NE, the manifold air
pressure PB and the PB map
11, or on the basis of the engine speed NE, the
throttle opening θTH and the TH map
12. An injection quantity determination
unit
107 determines the fuel injection quantity Tout on the basis of the
basic injection quantity Ti, the total correction factor Ktotal, the correction
factor by a gear Kgpd and an accelerated correction value Tacc and the like.
Referring to the flowchart of FIG. 3, a description will be made of the
operation of the fuel injection control unit
10 in detail. This handling
is executed by interruption due to a crank pulse in a predetermined stage.
In a step S
1, the engine speed NE is read. In a step S
2, the throttle
opening θTH is read. In a step S
3, an hour rate of change ΔθTH
of the throttle opening θTH is calculated on the basis of a differential
between a previous value for the throttle opening θTH obtained by detecting
in the step S
2 and this value. In a step S
4, the manifold air pressure
PB is read. In a step S
5, the hour rate of change ΔθTH of the
throttle opening θTH is compared with the basic rate of change ΔθThref
in the state judgment unit
104.
If the rate of change ΔθTH is under the basic rate of change ΔθTHref,
the sequence will proceed to a step S
11 by judging that the throttle handling
is slow and the engine is in a steady state. In the step S
11, the PB map
11 is selected by the map selection unit
105. In a step S
12,
the PB map
11 is retrieved on the basis of the engine speed NE and the manifold
air pressure PB to determine the basis injection quantity Ti. In a step S
13,
the final fuel injection quantity Tout is calculated by adding a further predetermined
acceleration correction quantity Tacc and invalid injection time TiVB, to a product
of the basic injection quantity Ti and the total correction factor Ktotal obtained
by the correction factor calculation unit
101.
The acceleration correction quantity Tacc is calculated in response to, for example,
the rate of change of the throttle opening. The invalid injection time TiVB is
a time period, of the intake-valve opening time period, which is not accompanied
by perfect injection of fuel. The invalid injection time TiVB is determined by
a type and structure of the fuel injection valve
8.
On the other hand, if the rate of change ΔθTH exceeds the basic rate
of change ΔθTHref, the sequence will proceed to the step S
6
by judging the engine to be in a transient state. In the step S
6, the TH
map
12 is selected by the map selection unit
105. In the step S
7,
the TH map
12 is retrieved on the basis of the engine speed NE and the throttle
opening θTH to determine the basic injection quantity Ti. In the step S
8,
"Gear discrimination" is executed in the gear position discrimination unit
102.
Gear discrimination occurs when the present gear position Ngp is discriminated
on the basis of the engine speed NE and the vehicle speed Vpls.
FIG. 4 is a flowchart showing a procedure of the above-described "Gear discrimination."
In a step S
701, it is judged whether or not this vehicle speed sensor
7
is normally operating on the basis of an output signal from a vehicle speed sensor
7. If out of order, the sequence will proceed to a step S
716 and
"0" is set in a gear position (GP) counter Ngp. If it is normally operating, the
sequence will proceed to a step S
702 to compare the vehicle speed Vpls with
the reference vehicle speed Vref. This reference vehicle speed Vref is a reference
value for judging whether or not the vehicle is traveling at low speed, and has
been set to, for example, several km/h.
If the vehicle speed Vpls exceeds the reference vehicle speed Vref, the sequence
will proceed to a step S
703 to compare a gear ratio NEV (=NE/Vpls) with
a first reference gear ratio NEVref
1. If the gear ratio NEV is smaller than
the first reference gear ratio NEVref
1, "1" is set in the GP counter Ngp
in a step S
704, indicating that the transmission is at the first stage.
In this respect, in the step S
702, even when the vehicle speed Vpls is judged
to be lower than the reference vehicle speed Vref, "1" is set to the GP counter
Ngp in the step S
704.
On the other hand, if it is judged in the step S
703 that the gear ratio
NEV exceeds the first reference gear ratio Vref
1, the sequence will proceed
to a step S
705, in which the gear ratio NEV will be compared with a second
reference gear ratio NEVref
2. If the gear ratio NEV is smaller than the
second reference gear ratio NEVref
2, "2" will be set to the GP counter Ngp
in a step S
706.
Similarly, if it is judged in the step S
705 that the gear ratio
NEV exceeds the second reference gear ratio NEVref
2, the sequence will proceed
to a step S
707, in which the gear ratio NEV will be compared with a third
reference gear ratio NEVref. If the gear ratio NEV is smaller than the third reference
gear ratio NEVref, "3" will be set to the GP counter Ngp in a step S
708.
Hereinafter, similarly, if it is judged in the step S
709 that
the gear ratio NEV is lower than the fourth reference gear ratio NEVref
4,
"4" will be set to the GP counter Ngp in a step S
710. If it is judged in
the step S
711 that the gear ratio NEV is lower than the fifth reference
gear ratio NEVref5, "5" will be set to the GP counter Ngp in a step S
712.
If it is judged in the step S
713 that the gear ratio NEV is lower than the
sixth reference gear ratio NEVref
6, "6" will be set to the GP counter Ngp
in a step S
714, and if it is judged in the step S
713 that the gear
ratio NEV exceeds the sixth reference gear ratio NEVref
6, "7" will be set
to the GP counter Ngp in a step S
715.
When registration of the gear position to the GP counter Ngp is completed as
described above, "Kgpd calculation" for calculating the correction factor by a
gear Kgpd is executed in the Kgpd calculation unit
103 on the basis of the
registered value of this GP counter Ngp in a step S
9 of FIG. 3.
FIG. 5 is a flowchart showing the procedure of the above-described "Kgpd calculation."
In a step S
801, it is judged which map has been selected in the map selection
unit
105. If the TH map
12 has been selected, the sequence will proceed
to a step S
802 to compare the cooling water temperature TW with the reference
temperature Twref. If the cooling water temperature TW exceeds the reference temperature
Twref, the above-described GP counter Ngp will be referred to in steps S
803,
S
804 and S
805.
If the GP counter Ngp indicates "5" or "6," an NE/Kgpdh table for during low
load
to be described later will be retrieved on the basis of the engine speed NE in
a step S
806. The retrieval result will be registered as a provisional value
Kgpd
0 of Kgpd. Similarly, if the GP counter Ngp indicates "3" or "4," an
NE/kgpdm table for during middle load to be described later will be retrieved on
the basis of the engine speed NE in a step S
807. The retrieval result will
be registered as the provisional value Kgpd0. Similarly, if the GP counter Ngp
indicates "1" or "2," an NE/Kgpdl table for during high load to be described later
will be retrieved on the basis of the engine speed NE in a step S
808. The
retrieval result will be registered as the provisional value Kgpd
0.
FIG. 6 is a view showing the contents of each of the above-described tables
schematically and superimposed. For each engine speed NE, there has been registered
each correction factor Kgpdh, Kgpdm and Kgpdl corresponding thereto. In the present
embodiment, each correction factor has been selected such that each correction
factor at the engine speed NE indicates a tendency of Kgpdh (high load)>Kgpdm
(middle load)>Kgpdl (low load). Specifically, in the present embodiment, the
smaller the engine load becomes, the smaller the value of the correction factor
becomes. As a result, the injection quantity of fuel is reduced. With regard to
the relationship between the engine speed NE and each correction factor, registration
is made with only 7 items among the engine speeds NE. Any other relationship can
be determined through interpolation.
Referring again to FIG. 5, in the step S
810, a θTH/Kgpth table
is retrieved on the basis of the throttle opening θTH. The retrieval result
will be registered as the throttle correction factor Kgpth. In the step S
811,
the correction factor by a gear Kgpd is calculated as a product of the provisional
value Kgpd
0 of the Kgpd and the throttle correction factor Kgpth.
In this respect, if the GP counter Ngp indicates "0" or the judgment in the steps
S
801 and S
802 is negative, the correction factor by a gear Kgpd will
be set to "1.0" irrespective of the data tables and the throttle correction factor
Kgpth in the step S
809.
Referring again to FIG. 3, in the step S
10, the final fuel injection
quantity Tout will be calculated by further adding a predetermined acceleration
correction quantity Tacc and invalid injection time TiVB to a product of the basic
injection quantity Ti, the total correction factor Ktotal, and the correction factor
by gear Kgpd obtained by the Kgpd calculation unit
103.
In the step S
14, a driving signal of the fuel injection valve
8
is outputted only during the fuel injection quantity Tout. The fuel injection valve
8 is opened only in a time period during which this driving signal is being
outputted to inject the fuel.
According to the present invention, the following effects will be exhibited.
Since there is provided means for discriminating a gear position of the transmission
in such a manner that the basic injection quantity is corrected on the basis of
the discrimination result of the gear position, the optimum fuel injection quantity
can be obtained in response to the engine load even if the engine speed NE and
the throttle opening θTH are the same.
Since the correction factor is determined as a function of a gear position
and this correction factor is multiplied by the fuel injection quantity in order
to determine the optimum fuel injection quantity for each gear position, the optimum
fuel injection quantity for each gear position can be obtained without providing
a TH map for each gear position.
Since it has been arranged such that the lower the gear position becomes, the
more the fuel injection amount reduced, it is possible to improve the specific
fuel consumption during a low-speed traveling load.
The invention being thus described, it will be obvious that the same may be varied
in many ways. Such variations are not to be regarded as a departure from the spirit
and scope of the invention, and all such modifications as would be obvious to one
skilled in the art are intended to be included within the scope of the following claims.
*
