Title: Valve timing control system for an internal combustion engine
Abstract: A valve timing control system for an internal combustion engine is provided, which includes: a crank angle sensor detecting a crank angle corresponding to an internal combustion engine crank shaft rotational angle; an actuator relatively modifying phases of a cam angle with the crank angle; a cam angle sensor detecting the cam angle modified by the actuator; an oil control valve driving the actuator; a target value detection unit calculating a target value according to the internal combustion engine operation state; a cam angle control unit controlling the detected cam angle to coincide with the calculated target value; a learning unit learning a control signal to the oil control valve when the cam angle substantially coincides with the target value; and a failure detection unit detecting failure of the actuator. The failure detection unit modifies a failure detection condition according to whether learning is performed in the learning unit.
Patent Number: 6,923,150 Issued on 08/02/2005 to Takahashi
| Inventors:
|
Takahashi; Tatsuhiko (Hyogo, JP)
|
| Assignee:
|
Mitsubishi Denki Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
655214 |
| Filed:
|
September 5, 2003 |
Foreign Application Priority Data
| May 29, 2003[JP] | 2003-153025 |
| Current U.S. Class: |
123/90.15; 123/90.16; 123/90.17 |
| Intern'l Class: |
F01L 001/34 |
| Field of Search: |
123/9015- 9018,903.1
74/568.R
464/1,2,160
92/121,122
|
References Cited [Referenced By]
U.S. Patent Documents
| 5333577 | Aug., 1994 | Shinojima.
| |
| 5664529 | Sep., 1997 | Kato et al.
| |
| 5715779 | Feb., 1998 | Kato et al.
| |
| Foreign Patent Documents |
| 06-159105 | Jun., 1994 | JP.
| |
| 2000/-064862 | Feb., 2000 | JP.
| |
Primary Examiner: Denion; Thomas
Assistant Examiner: Corrigan; Jaime
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
1. A valve timing control system for an internal combustion engine, comprising:
crank angle detection means for generating a crank angle position signal corresponding
to a rotational angle of a crank shaft in an internal combustion engine;
cam angle modifying means for modifying at least a relative position of a crank
shaft and a cam shaft for one of air intake and gas exhaust;
cam angle detecting means for detecting a cam angle modified by the cam angle
modifying means;
drive means for driving the cam angle modifying means;
target value calculating means for calculating a target value depending on an
operation state of the internal combustion engine;
cam angle control means for controlling the cam angle detected by the cam angle
detecting means to coincide with the target value calculated by the target value
calculating means;
learning means for learning a control signal outputted to the drive means at
a time when the target value and the cam angle substantially coincide; and
failure detecting means for detecting a failure of the cam angle modifying means,
wherein the failure detecting means modifies a failure detection condition according
to whether or not learning is completed by the learning means.
2. A valve timing control system for an internal combustion engine according
to claim 1, wherein the failure detecting means modifies a duration until the failure
is detected, according to whether or not the learning is performed by the learning
means as the failure detection condition.
3. A valve timing control system for an internal combustion engine according
to claim 2, wherein the failure detecting means sets the duration until the failure
is detected to be longer before than after the learning is performed by the learning means.
4. A valve timing control system for an internal combustion engine according
to claim 1, wherein the failure detecting means uses the cam angle detected by
the cam angle detecting means as the failure detection condition.
5. A valve timing control system for an internal combustion engine according
to claim 4, wherein the failure detecting means sets the duration until the failure
is detected to be longer before than after the learning is performed by the learning means.
6. A valve timing control system for an internal combustion engine according
to claim 1, wherein the failure detecting means uses the target value calculated
by the target value calculating means and the cam angle detected by the cam angle
detecting means, as the failure detection condition.
7. A valve timing control system for an internal combustion engine according
to claim 6, wherein the failure detecting means sets the duration until the failure
is detected to be longer before than after the learning is performed by the learning means.
8. A valve timing control system for an internal combustion engine according
to claim 1, wherein the failure detecting means uses a differential between the
target value calculated by the target value calculating means and the cam angle
detected by the cam angle detecting means, as the failure detection condition.
9. A valve timing control system for an internal combustion engine according
to claim 8, wherein the failure detecting means sets a duration until the failure
is detected to be longer before than after the learning is performed by the learning means.
10. A valve timing control system for an internal combustion engine according
to claim 1, wherein the learning means holds a learning value even after an ignition
switch is turned off.
11. A valve timing control system for an internal combustion engine according
to claim 1, wherein, when the learning by the learning means is not performed,
failure detection by the failure detecting means is not performed.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve timing control system for an internal
combustion engine for controlling operation timings of an intake valve and an exhaust
valve of an internal combustion engine, and more particularly to detection of failure
of a valve timing control system.
2. Description of the Related Art
As a conventional valve timing control system for an internal combustion engine,
there is a technique in which an operation state of a cam angle modifying unit
is detected, a drive signal from a drive unit in a given operation state is learned,
and based on this learned value, the drive signal to be calculated by a control
unit is compensated (for example, a technique disclosed in JP 06-159105 A).
The above-mentioned conventional valve timing control system for the internal
combustion engine includes: a relative rotational angle detection unit for detecting
a relative cam angle from a crank angle sensor and a cam angle sensor; a target
relative rotational angle calculating unit for calculating a target cam angle which
is optimal depending on the engine operation state; a learning unit for learning
an output value outputted from a control unit to a drive unit, which was calculated
based on a differential between the target relative rotational angle calculated
by the target relative rotational angle calculating unit and the relative cam angle
detected by the relative rotational angle detecting unit; the control unit for
controlling the drive unit according to information obtained from the relative
rotational angle detection unit, the target relative rotational angle calculation
unit, and the learning unit; the drive unit for driving a valve timing adjusting
unit; and the valve timing adjusting unit for modifying the cam angle with respect
to the crank angle.
The learning unit learns the output value outputted from the control unit to
the drive unit if the differential between the detected value detected by the relative
rotational angle detection unit and the calculated value calculated by the target
relative rotational angle calculation unit is within a predetermined range. The
control unit calculates a control amount based on the learning value and drives
the drive unit such that the target relative rotational angle and the relative
rotational angle coincide, and makes the valve timing adjusting unit operate at
a predetermined operating speed.
Further, there is a valve timing control system for an internal combustion
engine, which executes a failure determination if the differential between the
target value and the detected value is greater than a predetermined value continuously
for a predetermined time duration (for example, a technique disclosed in JP 2000-64862 A).
The conventional valve timing control systems for an internal combustion engine
are constructed as described above. According to those techniques, in a case where
the drive unit control amount learning value has not yet been learned, the valve
timing adjusting unit does not operate at the predetermined operation speed. As
a result, in the case where the failure is to be determined in the case where differential
between the target value and the detection value continues for the predetermined
time duration, there is a danger of the failure being determined erroneously.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above-mentioned problems, and
therefore has as an object to provide a valve timing control system for an internal
combustion engine, which can prevent an erroneous failure determination, even in
a state where a control amount learning value has not yet been learned and is not
yet at a correct value.
A valve timing control system for an internal combustion engine according to
the
present invention includes: a crank angle detection unit for generating a crank
angle position signal corresponding to a rotational angle of a crank shaft in an
internal combustion engine; a cam angle modifying unit for modifying at least a
relative position of a crank shaft and a cam shaft for one of air intake and gas
exhaust; a cam angle detecting unit for detecting a cam angle modified by the cam
angle modifying unit; a drive unit for driving the cam angle modifying unit; a
target value calculating unit for calculating a target value depending on an operation
state of the internal combustion engine; a cam angle control unit for controlling
the cam angle detected by the cam angle detecting unit to coincide with the target
value calculated by the target value calculating unit.
Further, the valve timing control system for an internal combustion engine
according to the present invention includes: a learning unit for learning a control
signal outputted to the drive unit at a time when the target value and the cam
angle substantially coincide; and a failure detecting unit for detecting a failure
of the cam angle modifying unit, in which the failure detecting unit modifies a
failure detection condition according to whether or not learning is completed by
the learning unit.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 is a constructional diagram showing a valve timing control system for
an internal combustion engine according to the present invention;
FIG. 2 is a flowchart of selection of a cam angle control mode which is a valve
timing, for explaining operations of the present invention;
FIG. 3 is a flowchart of a control amount calculation, for explaining operations
of the present invention;
FIG. 4 is a flowchart of holding current learning, for explaining operations
of the present invention;
FIG. 5 is a flowchart of a failure determination according to Embodiment 1 of
the present invention;
FIG. 6 is a flowchart of a failure determination according to Embodiment 2 of
the present invention;
FIG. 7 is a flowchart of a failure determination according to Embodiment 3 of
the present invention;
FIG. 8 is a flowchart of a failure determination according to Embodiment 4 of
the present invention;
FIG. 9 is a flowchart of a failure determination according to Embodiment 5 of
the present invention; and
FIG. 10 is a flowchart of a failure determination according to Embodiment 6
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiment 1
FIG. 1 is a constructional diagram illustrating a valve timing control system
for an internal combustion engine according to the present invention. The valve
timing control system for the internal combustion engine shown in FIG. 1 includes:
an internal combustion engine
101; an air cleaner
102 for cleansing
air taken in by the internal combustion engine
101; an airflow sensor
103
for quantifying an air amount taken in by the internal combustion engine
101;
an intake pipe
104; a throttle valve
105 for adjusting an intake
air amount and controlling an output of the internal combustion engine
101;
an injector
106 for providing fuel appropriate for the intake air amount;
and a spark plug
111 for generating sparks to burn an air-fuel mixture in
a combustion chamber of the internal combustion engine
101.
Further, there is provided: an ignition coil
110 for providing high-voltage
energy to the spark plug
111; an exhaust pipe
107 for emitting burned
exhaust gas; an O2 sensor
108 for detecting a remaining oxygen amount in
the exhaust gas; a three-way catalyst
109 capable of simultaneously cleansing
THC, CO, and NOx, which are harmful gasses in the exhaust gas; a sensor plate
116
which is provided with a protrusion (not shown in the diagram) at a given position,
and serves to detect an angle of a crank attached to a crank shaft and rotated
integrally with the crank shaft; and a crank angle sensor
115 for detecting
a position of the crank shaft, in which a signal is emitted when the protrusion
(not shown in the diagram) from the sensor plate
116 crosses the crank angle
sensor
115, to thus detect the crank angle.
Further, there are provided: an actuator
113 serving as a cam angle
modifying unit capable of phase-shifting the cam angle relative to the crank angle;
a cam angle sensor
112 for emitting the pulse signal caused by the protrusion
from the cam angle detection sensor plate, not shown in the diagram like the crank
angle sensor, to detect the cam angle; an oil control valve (hereinafter, referred
to as an OCV)
114 serving as a driving unit for driving the actuator
113,
which switches an oil pressure to the actuator
113 for modifying a cam phase
to control the cam phase; and an ECU
117 for performing cam phase control
and also performing control of the internal combustion engine
101.
Next, before explaining the cam phase angle control, first, explanation is
made of the control of the internal combustion engine
101. The air amount
taken in by the internal combustion engine
101 is measured by the air flow
sensor
103, and the ECU
117 calculates the fuel amount appropriate
for the measured air amount and drives the injector
106. Also, the ECU
117
controls timings of electrification and severance of the ignition coil
110,
for creating sparks to the air-fuel mixture in the combustion chamber by the spark
plug
111 at appropriate timings. The intake air amount is adjusted by the
throttle valve
105, and an output from the internal combustion engine
101
is controlled.
The exhaust gas combusted inside the cylinder is emitted through the exhaust
pipe
107, and by means of the catalyst
109 provided midway in the
exhaust pipe
107, the harmful substances HC, CO, and NOx in the exhaust
gas are cleansed to CO2 and H2O. In order to maximize the cleansing rate at the
catalyst
109, the O2 sensor
108 is attached to the exhaust pipe
107
to detect the remaining oxygen amount in the exhaust gas, and the ECU
117
performs the feedback control and adjusts the fuel amount such that the mixed air
reaches a theoretical air-fuel ratio.
Next, explanation is made of a valve timing control method by the ECU
117.
FIG. 2 shows a flowchart of selection of a cam angle control mode which is the
valve timing, the flowchart structuring: a target value calculating unit for calculating
a target value according to an operation state of the internal combustion engine;
and a cam angle control unit for controlling the cam angle detected by the cam
angle detection sensor
112 to coincide with the target value. This processing
is performed at a predetermined timing, for example, every 25 [ms].
First, at step S
201, a target phase angle (Vt) is calculated. For example,
reference is made to a map including a filling efficiency calculated from the intake
air amount (the value detected by the air flow sensor
103), and an RPM calculated
from the output from the crank angle sensor
115. At step S
202, a
detected phase angle (Vd) is detected. The detected phase angle is calculated by
measuring a time duration between output signals of the crank angle sensor
115
and the cam angle sensor
112. After that, a phase angle differential (dV)
shown in the following formula is calculated at step S
203.
Then, at step S
204 it is determined whether the target phase angle (Vt)
is 0 [degCA] or less. If it is 0 [degCA] or less, then at step S
206, the
cam control mode changes to a delay angle mode. At step S
204, if the target
phase angle (Vt) is greater than 0, then at step S
205, it is determined
whether the absolute value of the phase angle differential (dV) is 1 [degCA] or
more. If it is 1 [degCA] or more, then at step S
207, the cam control mode
changes to a proportionate differential control mode (hereinafter, referred to
as a PD mode). If it is smaller than 1 [degCA], then at step S
208, the cam
control mode changes to a holding mode.
Next, FIG. 3 is a flowchart of a calculation of a control amount (control current
value) to the OCV
114 by the ECU
117. Following the flowchart of
FIG. 2, this processing is performed at a predetermined timing, for example, every
25 [ms]. First, at step S
301, it is determined whether the cam control mode
is the delay angle mode. If it is the delay angle mode, then at step S
303,
the control current value (I) is set to 0 [mA]. If it is not the delay angle mode,
then at step S
302, it is determined whether the cam control mode is the
holding mode. If it is the holding mode, then at step S
304, an integral
value (Ii)=phase angle differential (dV)×integral gain (Igain) is calculated.
Then, at step S
305, the control current value (I)=holding current learning
value (Ih)+integral value (Ii) is calculated.
At step S
302, if the cam control mode is not the holding mode, then it
is judged as the PD mode, and at step S
306, the proportional value (Ip)=phase
angle differential (dV)×proportional gain (Pgain) is calculated. At step S
307,
the differential value (Id)=(phase angle differential (dV)-;previous phase angle
differential (dV[i-;1]))×differential gain (Dgain) is calculated. At step
S
308, the control current value (I)=holding current learning value (Ih)+proportional
value (Ip) +differential value (Id)+integral value (Ii) is calculated. The calculated
control current value (I) is converted into a duty value, and the OCV
114
is duty-controlled.
Next, FIG. 4 shows a flowchart of the holding current learning by the ECU
117.
The flowcharts of FIGS. 3 and 4 collectively structure a learning unit for learning
the control amount (the control current value) to the OCV
114 at the time
when the target phase angle and the cam angle substantially coincide. This processing
is performed at a predetermined timing, for example, every 25 [ms].
First, at step S
401, it is determined whether the cam control mode
is the holding mode. If it is not the holding mode, then the processing ends there.
If it the holding mode, then at step S
402, it is determined whether a learning
condition is obtained. The learning condition is that, for example, a difference
between the target phase angle and the detected phase angle is within a given range
(within±0.3 [degCA]) for a given time period (100 [ms]). In a case where the
learning condition is not obtained, the processing ends there.
In a case where the learning condition is obtained, then at step S
403,
the holding current learning value (Ih) is added to the integral value (Ii), and
the holding current learning value (Ih) is updated. At step S
404, a flag
is set so as to distinguish that the learning of the holding current learning value
is completed. At step S
405, the difference between the previous holding
current learning value (Ih [i-;1]) and the holding current learning value (Ih)
is subtracted from the integral value (Ii). The holding current learning value
and the holding current learning completion flag are backed up with a battery,
and even after the ignition key is turned off, their values are held.
Next, FIG. 5 is a flowchart showing an ECU
117 failure determination
and structuring a failure determination unit for determining failure of the actuator
113 serving as the cam angle modifying unit. A failure detection condition
is modified according to whether or not the above-mentioned learning is performed
by the learning unit. This processing is executed at predetermined periods, for
example, every 25 [ms].
First, at step S
501, it is determined whether the cam control mode
is the PD mode. If it is not the PD mode, then at step S
502, a failure determination
counter (Cf) is set to 0 [sec] and this processing ends. If it is the PD mode,
then at step S
503, it is determined whether the detected phase angle (Vd)
is 0 [degCA] or less. If the detected phase angle (Vd) is not 0 [degCA] or less,
then at step S
504, the failure determination counter (Cf) is set to 0 [sec],
and at step S
505, it is determined whether the phase angle differential
(dV) absolute value is 5 [degCA] or less. If it is 5 [degCA] or less, then at step
S
506, it is determined to be normal.
At step S
503, if the detected phase angle (Vd) is 0 [degCA] or less, then
at step S
507, the failure determination counter (Cf) counts upward. At step
S
508, it is determined whether the learning completion flag of the holding
current learning value has been set. If it has been set, then at step S
509,
it is determined whether a time period of 5 [sec] or more has elapsed by the failure
determination counter (Cf). If the time period of 5 [sec] or more has elapsed,
then at step S
510, the failure is determined. If the holding current learning
completion flag has not been set at step S
508, then at step S
511,
it is determined whether a time period of 10 [sec] or more has elapsed by the failure
determination counter (Cf). If the time period of 10 [sec] or more has elapsed,
then at step S
512, the failure is determined.
In this way, based on whether or not the holding current learning value has already
been learned, the failure determination delay time which is the failure determination
counter compared value is modified, and at the time when the holding current learning
value has already been learned the delay time is shorter than when it has not yet
been learned. Accordingly, erroneous failure detection can be prevented when the
learning has not yet been performed, and the failure detection can be performed
faster at the time when the learning has already been performed.
Further, by switching between performing and not performing the failure
determination according to the detected phase angle condition, the erroneous failure
determination can be eliminated. Further, the holding current learning value and
the learning completion flag are backed by the battery. Therefore, if the learning
is performed once, then that value is saved as long as the battery is not removed,
and thus an early failure detection becomes possible.
Embodiment 2
FIG. 6 is a flowchart of a failure determination according to Embodiment 2.
This processing is performed at predetermined periods, for example, every 25 [ms].
First, at step S
601, it is determined whether the cam control mode is the
PD mode. If it is not the PD mode, then at step S
602, the failure determination
counter (Cf) is set to 0 [sec], and this processing ends. If it is the PD mode,
then at step S
603, it is determined whether the target phase angle (Vt)
is 20 [degCA] or more. If the target phase angle (Vt) is below 20 [degCA], then
at step S
602, the failure determination counter (Cf) is set to 0 [sec],
and this processing ends.
At step S
603, if the target phase angle (Vt) is 20 [degCA] or more, then
at step S
604, it is determined whether the detected phase angle (Vd) is
5 [degCA] or less. If it is not 5 [degCA] or less, then at step S
605, the
failure determination counter (Cf) is set to 0 [sec], and at step S
606,
it is determined whether the phase angle differential (dV) absolute value is 5
[degCA] or less. If it is 5 [degCA] or less, then at step S
607, it is determined
to be normal. If the detected phase angle (Vd) is 5 [degCA] or less at step S
604,
then at step S
608, the failure determination counter (Cf) counts upward.
At step S
609, it is determined whether the learning completion flag of
the holding current learning value has been set. If it has been set, then at step
S
610, it is determined whether the failure determination counter (Cf) has
counted 5 [sec] or more. If it has counted 5 [sec] or more, then at step S
611,
the failure is determined. At step S
609, if the learning completion flag
has not been set, then at step S
612, it is determined whether the failure
determination counter (Cf) has counted 10 [sec] or more. If it has counted 10 [sec]
or more, then at step S
613, the failure is determined.
In this way, by switching between determining and not determining the failure
using the target phase angle value and the detected phase angle value, and by not
performing the failure determination in the case where the target phase angle is
below the predetermined value, the erroneous failure determination can be eliminated.
Embodiment 3
FIG. 7 is a flowchart of a failure determination according to Embodiment 3.
This processing is performed at predetermined periods, for example, every 25 [ms].
First, at step S
701, it is determined whether the cam control mode is the
PD mode. If it is not the PD mode, then at step S
702, the failure determination
counter (Cf) is set to 0 [sec], and this processing ends. If it is the PD mode,
then at step S
703, it is determined whether the target phase angle (Vt)
is 20 [degCA] or more. If it is below 20 [degCA], then at step S
704, the
failure determination counter (Cf) is set to 0 [sec], and at step S
705,
it is determined whether the phase angle differential (dV) absolute value is 5
[degCA] or less. If it is 5 [degCA] or less, then at step S
706, it is determined
to be normal.
At step S
703, if the target phase angle (Vt) is 20 [degCA] or more, then
at step S
707, it is determined whether the learning completion flag of the
holding current learning value has been set. If it has been set, then at step S
708,
it is determined whether the detected phase angle (Vd) is 5 [degCA] or less. If
it is 5 [degCA] or less, then at step S
709, the failure determination counter
(Cf) counts upward. If it is not 5 [degCA] or less, then at step S
710, the
failure determination counter (Cf) is set to 0 [sec]. At step S
711, it is
determined whether the failure determination counter (Cf) is 5 [sec] or more. If
it is 5 [sec] or more, then at step S
712, the failure is determined.
At step S
707, if the learning completion flag has not been set, then at
step S
713, it is determined whether the detected phase angle (Vd) is 0 [degCA]
or less. If it is 0 [degCA] or less, then at step S
714, the failure determination
counter (Cf) counts upward. If it is not 0 [degCA] or less, then at step S
715,
the failure determination counter (Cf) is set to 0 [sec]. At step S
716,
it is determined whether the failure determination counter (Cf) is 10 [sec] or
more. If it is 10 [sec] or more, then at step S
717, the failure is determined.
In this way, the condition triggering the failure determination counter, which
is the detected phase angle condition, is switched depending on whether or not
the learning of the holding current learning value is performed. Further, the condition
triggering the failure determination counter, which is the detected phase angle
condition, is set smaller when the learning has not yet been performed than when
the holding current learning value has already been learned. Accordingly, the erroneous
failure determination can be eliminated, and the failure determination precision
can be improved.
Embodiment 4
FIG. 8 is a flowchart of a failure determination according to Embodiment 4.
This processing is performed at predetermined periods, for example, every 25 [ms].
First, at step S
801, it is determined whether the cam control mode is the
PD mode. If it is not the PD mode, then at step S
802, the failure determination
counter (Cf) is set to 0 [sec], and this processing ends. If it is in the PD mode,
then at step S
803, it is determined whether the phase angle differential
(dV) absolute value is 20 [degCA] or more. If it is below 20 [degCA], then at step
S
804, the failure determination counter (Cf) is set to 0 [sec], and at step
S
805, it is determined whether the phase angle differential (dV) absolute
value is 5 [degCA] or less. If it is 5 [degCA] or less, then at step S
806,
it is determined to be normal.
At step S
803, if the phase angle differential (dV) absolute value is 20
[degCA] or more, then at step S
807, the failure determination counter (Cf)
counts upward. At step S
808, it is determined whether the learning completion
flag of the holding current learning value has been set. If it has been set, then
at step S
809, it is determined whether the failure determination counter
(Cf) is 5 [sec] or more. If it is 5 [sec] or more, then at step S
810, the
failure is determined.
At step S
808, if the learning completion flag has not been set, then at
step S
811, it is determined whether the failure determination counter (Cf)
is 10 [sec] or more. If it is 10 [sec] or more, then at step S
812, the failure
is determined.
In this way, by setting the differential (the phase angle differential) between
the target phase angle and the detected phase angle as the counting condition for
the failure determination counter, when the differential is the predetermined value
or more, the failure determination counter counts to perform the failure determination.
Accordingly, the erroneous failure determination can be prevented, and the failure
determination precision can be improved.
Embodiment 5
FIG. 9 is a flowchart of a failure determination according to Embodiment 5.
This processing is performed at predetermined periods, for example, every 25 [ms].
First, at step S
901, it is determined whether the cam control mode is the
PD mode. If it is not the PD mode, then at step S
902, the failure determination
counter (Cf) is set to 0 [sec], and this processing ends. If it is in the PD mode,
then at step S
903, it is determined whether the learning completion flag
of the holding current learning value has been set. If the learning completion
flag has been set, at step S
904, it is determined whether the phase angle
differential (dV) absolute value is 20 [degCA] or more.
If the absolute value is below 20 [degCA], then at step S
906, the failure
determination counter (Cf) is set to 0 [sec], and at step S
907, it is determined
whether the phase angle differential (dV) absolute value is 5 [degCA] or less.
If it is 5 [degCA] or less, then at step S
908, it is determined to be normal.
At step S
904, if the phase angle differential (dV) absolute value is 20
[degCA] or more, then at step S
905, the failure determination counter (Cf)
counts upward. At step S
909, it is determined whether the failure determination
counter (Cf) is 5 [sec] or more. If it is 5 [sec] or more, then at step S
910,
the failure is determined.
At step S
903, if the learning completion flag has not been set, then at
step S
911, it is determined whether the phase angle differential (dV) absolute
value is 30 [degCA] or more. If it is below 30 [degCA], then at step S
913,
the failure determination counter (Cf) is set to 0 [sec], and at step S
914,
it is determined whether the phase angle differential (dV) absolute value is 5
[degCA] or less. If it is 5 [degCA] or less, then at step S
915, it is determined
to be normal.
At step S
911, if the phase angle differential (dV) absolute value is 30
[degCA] or more, then at step S
912, the failure determination counter (Cf)
counts upward. At step S
916, it is determined whether the failure determination
counter (Cf) is 10 [sec] or more. If it is 10 [sec] or more, then at step S
917,
the failure is determined.
In this way, when the differential (the phase angle differential) between the
target phase angle and the detected phase angle is the predetermined value or more,
the failure determination is performed, and depending on whether or not the holding
current learning has been performed, the differential (the phase angle differential)
condition between the target phase angle and the detected phase angle is modified.
Moreover, when the holding current learning has already been performed, the differential
condition value is set smaller than at the time when the holding current has not
been learned yet. Accordingly, the erroneous failure determination can be prevented,
and the failure determination precision can be improved.
Embodiment 6
FIG. 10 is a flowchart of a failure determination according to Embodiment 6.
This processing is executed at predetermined periods, for example, every 25 [ms].
First, at step S
1001, it is determined whether the cam control angle is
the PD mode. If it is not the PD mode, then at step S
1002, the failure determination
counter (Cf) is set to 0 [sec], and this processing ends. If it is the PD mode,
then at step S
1003, it is determined whether the learning completion flag
of the holding current learning value has been set. If it has not been set, then
at step S
1002, the failure determination counter (Cf) is set to 0 [sec],
and the processing ends.
If the flag has been set, then at step S
1004, it is determined whether
the detected phase angle (Vd) is 0 [degCA] or less. If it is not 0 [degCA] or less,
then at step S
1005, the failure determination counter (Cf) is set to 0 [sec],
and at step S
1006, it is determined whether the phase angle differential
(dV) absolute value is 5 [degCA] or less. If it is 5 [degCA] or less, then at step
S
1007, it is determined to be normal.
At step S
1004, if the detected phase angle (Vd) is 0 [degCA] or less,
then
at step S
1008, the failure determination counter (Cf) counts upward. At
step S
1009, it is determined whether a time period of 5 [sec] or more has
elapsed by the failure determination counter (Cf). If the time period of 5 [sec]
or more has elapsed, then at step S
1010, the failure is determined.
In this way, the failure determination is not performed at the time when the
holding
current learning value has not been learned. Accordingly, the erroneous determination
of the failure can be eliminated, and the failure determination precision can be improved.
As described above, according to the present invention, the valve timing control
system for an internal combustion engine can be provided, which can prevent the
erroneous failure determination, even in a state where the control amount learning
value has not yet been learned and is not yet at a correct value.
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