U.S. patent application number 11/359543 was filed with the patent office on 2006-08-31 for method and apparatus for controlling engine.
This patent application is currently assigned to HONDA MOTOR CO., LTD.. Invention is credited to Shumpei Hasegawa.
Application Number | 20060191516 11/359543 |
Document ID | / |
Family ID | 36848315 |
Filed Date | 2006-08-31 |
United States Patent
Application |
20060191516 |
Kind Code |
A1 |
Hasegawa; Shumpei |
August 31, 2006 |
METHOD AND APPARATUS FOR CONTROLLING ENGINE
Abstract
To provide a value to be replaced for an output of a manifold
pressure sensor in case of failure of the manifold pressure sensor
for detecting a manifold pressure for calculating the amount of
fuel injection. An abnormality determination unit outputs an
abnormal signal when an output voltage of a manifold pressure
sensor is not within a predetermined range. A manifold pressure
estimating unit calculates an estimated manifold pressure value on
the basis of the engine revolution, a throttle opening, and an
atmospheric pressure. The manifold pressure estimating unit uses
the estimated value as a substitute value of the output of the
manifold pressure sensor and continues to control the engine when
the manifold pressure sensor has failed.
Inventors: |
Hasegawa; Shumpei; (Saitama,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
HONDA MOTOR CO., LTD.
|
Family ID: |
36848315 |
Appl. No.: |
11/359543 |
Filed: |
February 23, 2006 |
Current U.S.
Class: |
123/479 |
Current CPC
Class: |
F02D 41/222 20130101;
F02D 2200/0406 20130101; Y02T 10/40 20130101 |
Class at
Publication: |
123/479 |
International
Class: |
F02D 41/22 20060101
F02D041/22 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2005 |
JP |
2005-050733 |
Claims
1. A method of controlling an engine having a manifold pressure
sensor, an atmospheric pressure sensor, an engine revolution
detector, and a throttle sensor, said method comprising the steps
of: calculating an estimated manifold pressure value on the basis
of an engine revolution, a throttle opening and an atmospheric
pressure when the manifold pressure sensor has failed; and
performing fuel injection control by using the estimated manifold
pressure value as a representative output value of the manifold
pressure sensor.
2. The method of controlling an engine according to claim 1,
further comprising the steps of: obtaining an output voltage of the
manifold pressure sensor, an output voltage of the atmospheric
pressure sensor, an output of the throttle sensor and an output of
the engine revolution detector; and calculating a physical value of
the atmospheric pressure on the basis of the output voltage of the
atmospheric pressure sensor.
3. The method of controlling an engine according to claim 1,
further comprising the steps of: determining whether the output
voltage of the manifold pressure sensor is between a predetermined
lower limit and a predetermined upper limit; and if the output
voltage is not between the predetermined lower limit and the
predetermined upper limit, then it is determined that the manifold
pressure sensor has failed, and said steps of calculating the
estimated pressure value and performing fuel injection control are
carried out.
4. The method of controlling an engine according to claim 2,
further comprising the steps of: determining whether the output
voltage of the manifold pressure sensor is between a predetermined
lower limit and a predetermined upper limit; and if the output
voltage is not between the predetermined lower limit and the
predetermined upper limit, then it is determined that the manifold
pressure sensor has failed, and said steps of calculating the
estimated pressure value and performing fuel injection control are
carried out.
5. The method of controlling an engine according to claim 1,
further comprising the steps of: determining whether the output
voltage of the manifold pressure sensor is between a predetermined
lower limit and a predetermined upper limit; if the output voltage
is between the predetermined lower limit and the predetermined
upper limit, then it is determined that the manifold pressure
sensor has not failed, and the manifold pressure is calculated from
an output of the manifold pressure sensor.
6. The method of controlling an engine according to claim 2,
further comprising the steps of: determining whether the output
voltage of the manifold pressure sensor is between a predetermined
lower limit and a predetermined upper limit; if the output voltage
is between the predetermined lower limit and the predetermined
upper limit, then it is determined that the manifold pressure
sensor has not failed, and the manifold pressure is calculated from
an output of the manifold pressure sensor.
7. The method of controlling an engine according to claim 5,
wherein said step of calculating the manifold pressure from an
output of the manifold pressure sensor includes the step of using a
coordinate table between an output voltage of the manifold pressure
sensor and an atmospheric pressure value calculated from an output
voltage of the atmospheric pressure sensor to calculate the
manifold pressure, said method further comprising the step of
performing fuel injection control by using the calculated manifold
pressure value.
8. The method of controlling an engine according to claim 6,
wherein said step of calculating the manifold pressure from an
output of the manifold pressure sensor includes the step of using a
coordinate table between the output voltage of the manifold
pressure sensor and the atmospheric pressure value calculated from
the output voltage of the atmospheric pressure sensor to calculate
the manifold pressure, said method further comprising the step of
performing fuel injection control by using the calculated manifold
pressure value.
9. An apparatus for controlling an engine having a manifold
pressure sensor, an atmospheric pressure sensor, an engine
revolution detector, and a throttle sensor, comprising: a failure
diagnostic unit that detects an abnormality of the manifold
pressure sensor; a pressure calculating unit that outputs an
estimated manifold pressure value in response to input of an engine
revolution, a throttle opening, and an atmospheric pressure value
according to mutual relations among preset values of the engine
revolution, the throttle opening, the manifold pressure, and the
atmospheric pressure value; and an engine control unit that
performs fuel injection control using the estimated manifold
pressure value as a typical value of the output value of the
manifold pressure sensor when an abnormality is detected in the
manifold pressure sensor.
10. The apparatus for controlling an engine according to claim 9,
wherein the failure diagnostic unit obtains an output voltage of
the manifold pressure sensor, an output voltage of the atmospheric
pressure sensor, an output of the throttle sensor and an output of
the engine revolution detector and calculates a physical value of
the atmospheric pressure on the basis of the output voltage of the
atmospheric pressure sensor.
11. The apparatus for controlling an engine according to claim 9,
wherein the failure diagnostic unit determines whether the output
voltage of the manifold pressure sensor is between a predetermined
lower limit and a predetermined upper limit, and if the output
voltage is not between the predetermined lower limit and the
predetermined upper limit, the failure diagnostic unit determines
that the manifold pressure sensor has failed, and the pressure
calculating unit outputs the estimated manifold pressure value and
the engine control unit performs fuel injection control.
12. The apparatus for controlling an engine according to claim 10,
wherein the failure diagnostic unit determines whether the output
voltage of the manifold pressure sensor is between a predetermined
lower limit and a predetermined upper limit, and if the output
voltage is not between the predetermined lower limit and the
predetermined upper limit, the failure diagnostic unit determines
that the manifold pressure sensor has failed, and the pressure
calculating unit outputs the estimated manifold pressure value and
the engine control unit performs fuel injection control.
13. The apparatus for controlling an engine according to claim 9,
wherein the failure diagnostic unit determines whether the output
voltage of the manifold pressure sensor is between a predetermined
lower limit and a predetermined upper limit, and if the output
voltage is between the predetermined lower limit and the
predetermined upper limit, the failure diagnostic unit determines
that the manifold pressure sensor has not failed, and the pressure
calculating unit calculates the manifold pressure from the output
voltage of the manifold pressure sensor.
14. The apparatus for controlling an engine according to claim 10,
wherein the failure diagnostic unit determines whether the output
voltage of the manifold pressure sensor is between a predetermined
lower limit and a predetermined upper limit, and if the output
voltage is between the predetermined lower limit and the
predetermined upper limit, the failure diagnostic unit determines
that the manifold pressure sensor has not failed, and the pressure
calculating unit calculates the manifold pressure from the output
voltage of the manifold pressure sensor.
15. The apparatus for controlling an engine according to claim 13,
wherein the pressure calculating unit calculating the manifold
pressure from the output voltage of the manifold pressure sensor by
using a coordinate table between an output voltage of the manifold
pressure sensor and an atmospheric pressure value calculated from
an output voltage of the atmospheric pressure sensor to calculate
the manifold pressure, and said engine control unit performs fuel
injection control by using the calculated manifold pressure
value.
16. The apparatus for controlling an engine according to claim 14,
wherein the pressure calculating unit calculating the manifold
pressure from the output voltage of the manifold pressure sensor by
using a coordinate table between the output voltage of the manifold
pressure sensor and the atmospheric pressure value calculated from
the output voltage of the atmospheric pressure sensor to calculate
the manifold pressure, and said engine control unit performs fuel
injection control by using the calculated manifold pressure value.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This nonprovisional application claims priority under 35
U.S.C. .sctn. 119(a) on Patent Application No. 2005-050733, filed
in Japan on Feb. 25, 2005, the entirety of which is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an engine control method
and apparatus. More specifically, the present invention relates to
an engine control method and apparatus in which fuel injection is
controlled using an intake manifold pressure value.
[0004] 2. Description of Background Art
[0005] In the background art, in an engine fuel injection control
system, a control method that is so-called a speed density method
for calculating a basic amount of fuel injection on the basis of a
negative pressure in an intake manifold (hereinafter referred to as
"manifold pressure") and the engine revolution is known. A manifold
pressure sensor is used for detecting the manifold pressure. In
general, in order to maintain a normal system operation, a
diagnostic apparatus for detecting a failure of the manifold
pressure sensor is employed. For example, Japanese Patent
Application Laid-Open No. 2003-307152 discloses an apparatus for
determining an output signal from a sensor for sensing the intake
manifold is within a preset range.
SUMMARY OF THE INVENTION
[0006] In a system having a failure diagnostic apparatus as
described above, it is desirable to be able to continue an
operation of the system even when the failure of the manifold
pressure sensor is detected.
[0007] It is an object of an embodiment of the present invention to
provide an engine control method and apparatus that enable
continuation of an operation even when an abnormality occurs in the
manifold pressure sensor in a system having manifold pressure
sensors.
[0008] In order to achieve the above-described object, an
embodiment of the present invention is directed to a method of
controlling an engine having a manifold pressure sensor, an
atmospheric pressure sensor, an engine revolution detector, and a
throttle sensor. An estimated manifold pressure value is calculated
on the basis of the engine revolution, a throttle opening, and an
atmospheric pressure when the manifold pressure sensor has failed.
Fuel injection control is performed by using the estimated manifold
pressure value as a typical output value of the manifold pressure
sensor.
[0009] According to the embodiment of the present invention having
the characteristic described above, the engine can be continuously
controlled with the estimated manifold pressure value in case of
failure of the manifold pressure sensor in the system in which the
control method employing the manifold pressure sensors is employed.
Therefore, an engine controlled by the control method of the
invention is highly reliable.
[0010] 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
[0011] 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:
[0012] FIG. 1 is a block diagram showing a function of a principal
portion of a diagnostic apparatus according to an embodiment of the
present invention;
[0013] FIG. 2 is a general drawing showing an engine control system
including the diagnostic apparatus according to the embodiment of
the present invention;
[0014] FIG. 3 is a block diagram showing a principal portion of the
engine control system including the diagnostic apparatus according
to the embodiment of the present invention;
[0015] FIG. 4 is a flowchart showing a process of the principal
portion of the diagnostic apparatus according to the embodiment of
the present invention;
[0016] FIG. 5 is a drawing showing an example of a data table used
in calculation of an estimated manifold pressure; and
[0017] FIG. 6 is a drawing showing another example of the data
table used in calculation of the estimated manifold pressure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] An embodiment of the present invention will now be described
with reference to the accompanying drawings, wherein the same or
similar elements will be identified with the same reference
numeral.
[0019] FIG. 2 is a block diagram of a principal portion of an
apparatus for controlling an engine including a failure diagnostic
apparatus. In FIG. 2, an engine 1 is a reciprocal internal
combustion engine for an airplane, and is provided with a starter
motor 2 for activation. Although components for two cylinders are
shown in FIG. 2, the number of cylinders in the engine 1 is not
limited. An intake manifold 3 of the engine 1 is provided with fuel
injection valves 4 and manifold pressure sensors 5. The manifold
pressure sensors 5 are located on the upstream side of the fuel
injection valves 4 for detecting a pressure in the intake manifold
3. In order to differentiate the two manifold pressure sensors 5,
the one for main control will be referred to hereinafter as a first
manifold pressure sensor 5A and the one for back-up will be
referred to hereinafter as a second manifold sensor 5B.
[0020] A throttle body 6 is provided on the upstream side of the
manifold pressure sensor 5. A throttle valve 7 is assembled in the
throttle body 6. The throttle valve 7 is driven by a motor 8. The
throttle body 6 is provided with a throttle sensor 6A for detecting
a throttle opening. Known sensors required for controlling the
engine such as an atmospheric pressure sensor 9, a cam pulser 10, a
crank pulser 11, a cooling water temperature sensor 12, and an air
temperature sensor 13, etc. are further provided for controlling
the engine 1.
[0021] An electronic control unit (ECU) 14 is also included for
performing fuel injection or ignition control according to a
program upon reception of output signals from the respective
sensors described above. The ECU 14 includes a failure diagnostic
function for the manifold pressure sensors 5.
[0022] FIG. 3 is a block diagram showing a general structure of the
engine control system described above. As shown in FIG. 3, the
control system of this embodiment is provided with two systems of
detection circuits for the sensors and the ECUs 14 as failsafe
devices. These systems are referred to as an A lane 100 and a B
lane 200, respectively. The A lane 100 includes an A sensor group
101 including the sensors described in conjunction with FIG. 2, an
A power source 102, and an ECU 14A for the A lane. Likewise, the B
lane 200 includes a B sensor group 201, a B power source 202, and
an ECU 14B for the B lane. The first manifold pressure sensor 5A is
included in the A sensor group 101, and the second manifold
pressure sensor 5B is included in the B sensor group 201. Although
the atmospheric pressure sensors 9 (9a and 9b) are provided on
circuit boards which constitute the ECU 14A and the ECU 14B or in
housings (not shown) of the ECUs 14A and 14B in this embodiment,
the positions of installation of the atmospheric pressure sensors 9
are not limited thereto.
[0023] The ECUs 14A and 14B are capable of communicating with each
other in both ways via communication interfaces of one another, not
shown. One end (minus side) of each drive coil of the fuel
injection valve 4 provided for each cylinder (only one is shown) 15
is connected to injection signal output terminals OA and OB of the
ECUs 14A and 14B, respectively, via change-over switches 16, 17.
The other end of the drive coil 15 is connected to a power source
19, which outputs, for example, a voltage of 14 V via a power
switch 18. The power switch 18 is provided with a current control
function. The power sources 19 and the power switches 18 are
provided in the ECUs 14A and 14B, respectively.
[0024] A switching signal SA outputted form the ECU 14A is
connected to an input side of an AND circuit 20 on one side. A
switching signal SB outputted from the ECU 14B is connected to an
input side of the AND circuit 20 on the other side via a NOT
circuit 21. The output from the AND circuit 20 is supplied to the
change-over switch 16 and to a change-over switch 17 via another
NOT circuit 22.
[0025] Power is distributed from the power source 19 to the drive
coil 15 depending on the condition of the injection signal output
terminal of the lane which is connected to one of the change-over
switches 16, 17 selected by the switching signals SA and SB. The
valve-open duration of the fuel injection valve 4, i.e. the amount
of fuel injection, is determined by the duration of this power
distribution.
[0026] The diagnosis of the manifold pressure sensor of the main
control A lane 100 and compensation in case of failure will be
described below. The B lane 200 can be used for assisting the A
lane 100 when the A lane 100 is brought into an abnormal state and
the lane switching is performed. In this case, an example of using
a substitute value without switching the lane in the case in which
the A lane 100 is in the abnormal condition will be described.
[0027] FIG. 4 is a flowchart of the failure diagnostic process of
the manifold pressure sensor 5A. In Step S1, the ECU 14A is
initialized. In Step S2, an output voltage VPMa of the first
manifold pressure sensor 5A of the A lane 100, an output voltage
VPAa of the atmospheric pressure sensor 9a of the A lane 100, an
output PLP of the throttle sensor 6A, and a crank pulse PLS
outputted from the clank pulser 11 of the A lane 100 are read.
[0028] In Step S3, a physical value PAa (mm Hg) of the atmospheric
pressure is calculated on the basis of the output voltage VPAa. For
example, the output voltages are converted into physical values
using a prepared conversion table, respectively. In Step S3, the
engine revolution Ne is calculated on the basis of the crank pulse
PLS, for example by intervals of the crank pulses PLS.
[0029] In Step S4, whether or not the output voltage VPMa of the
manifold pressure sensor 5A exceeds a predetermined upper limit
value (4.5 V in this case) is determined. If the determination is
negative, the procedure goes to Step S5.
[0030] In Step S5, whether or not the voltage VPMa is smaller than
a predetermined lower limit value (0.5 V for example) is
determined. If the determination in this step is negative, the
procedure goes to Step S6, where a manifold pressure PMa is
calculated referring to the conversion table on the basis of the
output voltage VPMa of the manifold pressure sensor 5A.
[0031] When the determination in Step S4 is affirmative, it is
determined that the manifold pressure sensor 5A has failed due to
short circuit or the like. Therefore, the procedure goes to Step
S7. In Step S7, an estimated manifold pressure value PMcal is
calculated as a substitute of the output value of the manifold
pressure sensor 5A on the basis of the engine revolution Ne (rpm),
the throttle opening PLP (%), and the atmospheric pressure PAa
(mmHg).
[0032] When the determination in Step S5 is affirmative as well, it
is determined that the manifold pressure sensor 5A has failed due
to disconnection or the like. Therefore, the procedure goes to Step
S7 where the estimated manifold pressure value PMcal is
calculated.
[0033] The estimated manifold pressure value PMcal calculated in
Step S7 is used as a substitute value of a manifold pressure value
PMa detected by the manifold pressure sensor 5A (Step S8).
[0034] Subsequently, a specific example of relations among an
atmospheric pressure PA, the engine revolution Ne, the throttle
opening PLP, and the manifold pressure PMa used for obtaining the
estimated manifold pressure value PMcal will be described.
[0035] FIG. 5 is a data table showing the relations among the
engine revolution Ne, the atmospheric pressure PA, the manifold
pressure PMa, and the throttle opening PLP. The data is obtained
when the atmospheric pressure PA is set to 550 mm Hg in the test
apparatus in which the atmospheric pressure PA can be set to
various values, and the engine 1 is operated at various numbers of
revolutions Ne. The vertical axis represents the manifold pressure
PMa, and the lateral axis represents the throttle opening PLP. The
atmospheric pressure PA of 550 mm Hg, which is obtained when an
airplane having the engine 1 mounted thereon is cruising at a
height of 8000 feet in the air is assumed to be as a representative
atmospheric pressure.
[0036] Using the data shown in FIG. 5, the manifold pressure PMa
when the engine revolution Ne is 2300 rpm, and the throttle opening
PLP is 35% is obtained. In FIG. 5, when an intersection between a
line of 35% in the throttle opening PLP (vertical line) and a
curved line representing 2300 rpm in the engine revolution Ne is
represented as a point X, the manifold pressure PMa at the
intersection X can be read. In other words, the estimated manifold
pressure value PMcal can be obtained. The estimated manifold
pressure value PMcal obtained here is 420 mm Hg. The data shown in
FIG. 5 is stored in a memory unit in the ECUs 14A, 14B. The
estimated manifold pressure value PMcal can be calculated by
performing a functional calculation or a linear interpolation.
[0037] FIG. 6 is a drawing showing a relation between the manifold
pressure PMa at various atmospheric pressures (750 mm Hg, 550 mm
Hg, and 350 mm Hg) and the throttle opening PLP when the engine
revolution Ne is 2300 rpm.
[0038] A procedure without using the representative atmospheric
pressure, but using data in a characteristic curve as in FIG. 6 for
obtaining the estimated manifold pressure PMcal at an intermediate
atmospheric pressure which is not on the characteristic curve, will
be described. For example, assuming a flight at a height of 9500
feet, an example in which the atmospheric pressure PA is 520 mmHg,
the engine revolution Ne is 2300 rpm, and the throttle opening PLP
is 35% will be described. First, intersections between a line
(vertical line) showing 35% in the throttle opening PLP and the
characteristic lines of 350 mm Hg and 550 mm Hg in the atmospheric
pressure PA are represented in FIG. 6 as a point A and a point C,
respectively. An intersection B between the virtual characteristic
curve of 520 mm Hg in the atmospheric pressure and the line of 35%
in the throttle opening PLP is supposed to be at a midpoint between
the point A and the point C.
[0039] The manifold pressure PMa indicated by the point B can be
obtained by interpolating on the basis of the coordinates of the
point A, the point B, and the point C. In other words, the
coordinates of the respective points A, B, C (PLP, PMa, and PA) are
A (35, 250, 350), B (35, PMa, 520), and C (35, 415, 550). The
manifold pressure PMa is calculated by the following expression.
PMa=250+(415-250)/(550-350).times.(520.times.350)
[0040] According to this expression, the manifold pressure PMa is
obtained as 390 mm Hg, i.e. the estimated manifold pressure value
PMcal is obtained as 390 mm Hg.
[0041] For example, by creating the data tables as shown in FIG. 6,
in increments of 500 rpm from 500 rpm to the upper limit of usage
3000 rpm and storing these tables in the ECUs 14A and 14B, the
estimated manifold pressure value PMcal according to various
numbers of engine revolutions can be calculated.
[0042] FIG. 1 is a block diagram showing a function of a principal
portion of the ECU 14A, which performs the process described in
conjunction with the flowchart in FIG. 4. An abnormality
determination unit 35 determines the existence of an abnormality in
the manifold pressure sensor 5A depending on whether the output
voltage VPMa of the manifold pressure sensor 5A is out of a
predetermined voltage range (for example, 0.5 V to 4.5 V). If the
manifold pressure sensor 5A is normal, the output voltage VPMa is
supplied to a manifold pressure calculating unit 36. The manifold
pressure calculating unit 36 includes a coordinate table between
the voltage value VPMa and the pressure value PMa, and outputs the
pressure value PMa corresponding to the inputted voltage value
VPMa. The manifold pressure PMa is supplied to an engine control
unit 37 and is used to calculate the amount of fuel injection or
the timing of ignition.
[0043] When the manifold pressure sensor 5A is brought into a
failed state, the estimated manifold pressure value PMcal is
calculated in a manifold pressure estimating unit 30. The estimated
value PMcal is supplied to the engine control unit 37 as the
manifold pressure PMa.
[0044] In this manner, when the manifold pressure sensor is brought
into a failed state, the estimated manifold pressure value is
calculated using the output from a sensor other than the manifold
pressure sensor, which is determined to be failed. For example, the
engine revolution, the throttle opening or the atmospheric pressure
can be used instead of the manifold pressure. The calculated value
is used as a substitution of the output of the manifold pressure
sensor to continue the engine control.
[0045] 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.
* * * * *