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Claims  |
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We claim:
1. An electric control apparatus for electrically controlling a
controllable device mounted on an automobile, comprising:
measuring means for producing output data values representing at least one
state of the controllable device;
memory means for storing successive output data values of said measuring
means;
calculation means for calculating at a current time point an estimation
value representing said one state of said controllable device at a future
time point on the basis of an output data value of said measuring means at
a current time point and at least one output data value previously stored
in said memory means; and
operating processing means for calculating at least one control value to be
applied at a current time point to said controllable device on the basis
of the estimation value from said calculation means; wherein
said memory means includes means for storing successive output data values
received periodically from said measuring means; and
said calculation means includes means of reading out at least one output
data value previously stored in said memory means and for calculating at
least one changing value of the output data values of said measuring means
on the basis of the read-out output data value and an output data value
stored at a current time point from said measuring means to thereby
calculate the estimation value on the basis of the output data value
stored at the current time point and the changing value, means for reading
out an output data value stored in said memory means one period before and
for calculating a difference value between the output data value stored at
the current time point and the read-out output value to thereby calculate
the estimation value on the basis of the output data value at the current
time point and the difference value, and means for obtaining the
estimation value representing said one state at one period after adding
the output data value stored at the current time point to the difference
value.
2. An electric control apparatus for electrically controlling a
controllable device mounted on an automobile, comprising:
measuring means for producing output data values representing at least one
state of the controllable device;
memory means for storing successive output data values of said measuring
means;
calculation means for calculating at a current time point an estimation
value representing said one state of said controllable device at a future
time point on the basis of an output data value of said measuring means at
a current time point and at least one output data value previously stored
in said memory means; and
operating processing means for calculating at least one control value to be
applied to said controllable device on the basis of the estimation value
from said calculation means;
wherein said calculation means includes means for calculating a first
difference value between the output data value stored at the current time
point and the output data value stored one period before and a second
difference value between the output data values stored one and two periods
before to thereby calculate the estimation value on the basis of the first
and second difference values and the output data value stored in the
current time point, and means for calculating a third difference value
between the first and second difference values and for calculating the sum
of the output data value stored at the current time point and a difference
value between the first and third difference values to thereby obtain an
estimation value representing said state at one period after.
3. An electric control apparatus for electrically controlling a
controllable device mounted on an automobile, comprising:
measuring means for producing output data values representing at least one
state of the controllable device;
memory means for storing successive output data values of said measuring
means;
calculation means for calculating at a current time point an estimation
value representing said one state of said controllable device at a future
time point on the basis of an output data value of said measuring means at
a current time point and at least one output data value previously stored
in said memory means; and
operating processing means for calculating at least one control value to be
applied at a current time point to said controllable device on the basis
of the estimation value from said calculation means;
wherein said memory means includes means for storing successive output data
values received periodically from said measuring means and for storing a
coefficient proportional to a time constant of a step response of said
measuring means; and
said calculation means includes means for reading out at least one output
data value previously stored in said memory means and for calculating at
least one changing value of the output data values of said measuring means
on the basis of the read-out output data value and an output data value
stored at a current time point from said measuring means to thereby
calculate the estimation value on the basis of the coefficient, the output
value stored at the current time point and the changing value.
4. An electric control apparatus according to claim 3, wherein said
calculating means includes means for reading out the coefficient and an
output data value stored in said memory means one period before and for
calculating a difference value between the output data value stored at the
current time point and the read-out output value to thereby calculate the
estimation value on the basis of the output data value at the current time
point, the difference value and the coefficient.
5. An electric control apparatus according to claim 4, wherein said
calculating means includes means for obtaining the estimation value
representing said one state at one period after by adding the output data
value stored at the current time point to the difference value multiplied
by the coefficient.
6. An electric control apparatus according to claim 5, wherein said
coefficient is the time constant divided by a time equal to the one
period.
7. An electric control apparatus according to claim 6, wherein said
measuring means includes at least one sensor for producing output data
values representing at least one state of the controllable device and a
primary delay filter for filtering an output signal from the sensor to
output the output data value, and said time constant is a time constant
for a step response of the primary delay filter.
8. An electric control apparatus according to claim 6, wherein said
measuring means includes at least one sensor for producing output data
values representing at least one state of the controllable device and a
primary delay filter for filtering an output signal from the sensor to
output the output data value, and said time constant is a time constant
for a step response of the sensor and the primary delay filter.
9. An electric control apparatus for electrically controlling a
controllable device mounted on an automobile, comprising:
measuring means for producing output data values representing at least one
state of the controllable device;
memory means for storing successive output data values of said measuring
means;
calculation means for calculating at a current time point an estimation
value representing said one state of said controllable device at a future
time point on the basis of an output data value of said measuring means at
a current time point and at least one output data value previously stored
in said memory means; and
operating processing means for calculating at least one control value to be
applied at a current time point to said controllable device on the basis
of the estimation value from said calculation means;
detecting means for detecting a data value representing at least another
state of the controllable device; and
generating means for generating at least one value produced from a function
representing the state of the controllable device on the basis of the
detection data value of the detecting means; wherein
said memory means includes means for storing successive output data values
received periodically from said measuring means; and
said calculation means includes means for reading out at least one output
data value previously stored in said memory means and for calculating at
least one changing value of the output data values of said measuring means
on the basis of the read-out output data value and an output data value
stored at a current time point from said measuring means to thereby
calculate an estimation value on the basis of the output data value stored
at the current time point, the changing value, and the value produced from
the function.
10. An electric control apparatus according to claim 9, wherein said
calculation means includes means for reading out an output data value
stored in said memory means one period before, for calculating a
difference value between the output data value stored at the current time
point and the read-out output value, and for adding the output data value
at the current time point to the difference multiplied by the value
produced from the function to thereby obtain the estimation value
representing the state at one period after.
11. An electric control apparatus according to claim 9, wherein said
generating means includes means for generating first and second values
produced from respective first and second functions representing the state
of the controllable device on the basis of the detection data value of the
detecting means; wherein
said calculating means includes means for calculating a first difference
value between the output data value stored at the current time point and
the output data value stored one period before and a second difference
between the output data values stored one and two periods before and for
producing an estimation value representing the state at one period after
by adding the product of the second difference and the value produced from
the second function to the output data value stored at the current time
point.
12. An electric control apparatus according to claim 9, wherein the at
least another state of the controllable device is a running condition of
an automobile engine.
13. An apparatus for electrically controlling a controllable device mounted
on an automobile, comprising:
measuring means for producing output data values representing at least one
state of said controllable device mounted on the automobile;
filter means for filtering output data values from said measuring means;
memory means for storing successive output data values of said measuring
means;
calculating means for calculating at a current time point an estimation
value representing said one state of said controllable device at a future
time point on the basis of an output data value of said measuring means at
a current time point and at least one output data value previously stored
in said memory means;
judging means for judging whether the state of said controllable device is
in either one of a first state and a second state based on operating
condition data;
selecting means for selecting one of the estimation value and the filtered
output data value from said calculating means and said filter means in
accordance with the result of said judging means; and
operation processing means for calculating a control value on the basis of
the selected output of said selecting means and applying a control signal
representing the control value to said controllable device.
14. An apparatus according to claim 13, wherein said judging means includes
means for judging as the first and second states whether the state of said
controllable device is a transient state or a steady state, and said
selecting means includes means for selecting said estimation value from
said calculating means when said judging means judges the state as the
transient state and selecting the filtered output data value from said
filter means when said judging means judges the state as the steady state.
15. An apparatus according to claim 14, further comprising:
detecting means for detecting a data value representing at least another
state of the controllable device; and
generating means for generating at least one value produced from a function
representing the state of the controllable device on the basis of the
detection data value of the detecting means; wherein
said memory means includes means for storing successive output data values
received periodically from said measuring means; and
said calculating means includes means for reading out at least one output
data value previously stored in said memory means and for calculating at
least one changing value of the output data values of said measuring means
on the basis of the read-out output data value and an output data value
stored at a current time point from said measuring means to thereby
calculate an estimation value on the basis of the output data value stored
at the current time point, the changing value, and the value produced from
the function.
16. An electric control apparatus according to claim 15, wherein said
calculating means includes means for reading out an output data value
stored in said memory means one period before, for calculating a
difference value between the output data value stored at the current time
point and the read-out output value, and for adding the output data value
at the current time point to the difference multiplied by the value
produced from the function to thereby obtain the estimation value.
17. An apparatus according to claim 10, wherein
said memory means includes means for storing successive output data values
received periodically from said measuring means and for storing a
coefficient proportional to a time constant of a step response of said
measuring means; and
said calculating means includes means for reading out at least one output
data value previously stored in said memory means and for calculating at
least one changing value of the output data values of said measuring means
on the basis of the read-out output data value and an output data value
stored at a current time point from said measuring means to thereby
calculate the estimation value on the basis of the coefficient, the output
value stored at the current time point and the changing value.
18. An apparatus according to claim 17, wherein said calculating means
includes means for reading out the coefficient and an output data value
stored in said memory means one period before and for calculating a
difference value between the output data value stored at the current time
point and the read-out output value to thereby obtain the estimation value
by adding the output data value at the current time point to the
difference value multiplied by the coefficient.
19. An apparatus according to claim 13, wherein said judging means includes
means for judging as the first state when the output data value of said
measuring means is increasing at a ratio equal to or larger than a
predetermined ratio, and as the second state when the output data value is
increasing at a ratio smaller than the predetermined ratio, and said
selecting means includes means for selecting the outputs of said
calculating means and said filter means, respectively when said judging
means judges as the first and second states.
20. An apparatus according to claim 19, wherein
said memory means includes means for storing successive output data values
received periodically from said measuring means; and
said calculating means includes means for reading out at least one output
data value previously stored in said memory means and for calculating at
least one changing value of the output data values of said measuring means
on the basis of the read-out output data value and an output data value
stored at a current time point from said measuring means to thereby
calculate the estimation value on the basis of the output data value
stored at the current time point and the changing value.
21. An apparatus according to claim 20, wherein said calculating means
includes means for reading out an output data value stored in said memory
means one period before and for calculating a difference value between the
output data value stored at the current time point and the read-out output
value to thereby calculate the estimation value by adding the output data
value at the current time point to the difference value.
22. An apparatus according to claim 20, wherein said calculating means
includes means for reading out output data values stored in said memory
means one and two periods before, and means for calculating a first
difference value between the output data value stored at the current time
point and the output data value stored one period before, a second
difference between the output data values stored one and two periods
before, and a third difference value between the first and second
difference values and for calculating the sum of the output data value
stored at the current time point and a difference value between the first
and third difference values to thereby obtain an estimation value
representing said state at one period after.
23. An electrical control apparatus for electrically controlling a
controllable device mounted on an automobile comprising:
measuring means for producing output data values representing at least one
state of said controllable device mounted on the automobile;
memory means for storing successive output data of said measuring means;
calculating means for calculating at a current time point an estimation
value representing said one state of said controllable device at a future
time point on the basis of an output data value of said measuring means at
a current time point and at least one output data value previously stored
in said memory means; and
operation processing means for calculating a control value on the basis of
the estimation value and applying a control signal representing the
control value to said controllable device; wherein
said memory means includes means for storing successive output data values
received periodically from said measuring means; and
said calculating means includes means for reading out at least one output
data value previously stored in said memory means and for calculating at
least one changing value of the output data values of said measuring means
on the basis of the read-out output data value and an output data value
stored at a current time point from said measuring means to thereby
calculate the estimation value on the basis of the output data value
stored at the current time point and the changing value, and means for
reading out an output data value stored in said memory means one period
before and for calculating a difference value between the output data
value stored at the current time point and the read-out output value to
thereby calculate the estimation value on the basis of the sum of the
output data value at the current time point and the difference value.
24. An apparatus electrically controlling a controllable device mounted on
an automobile comprising:
measuring means producing output data values representing at least one
state of said controllable device mounted on the automobile;
memory means for storing successive output data of said measuring means;
calculating means for calculating at a current time point an estimation
value representing said one state of said controllable device at a future
time point on the basis of an output data value of said measuring means at
a current time point and at least one output data value previously stored
in said memory means; and
operation processing means for calculating a control value on the basis of
the estimation value and applying a control signal representing the
control value to said controllable device; wherein
said memory means includes means for storing successive output data values
received periodically from said measuring means; and
said calculating means includes means for reading out at least one output
data value previously stored in said memory means and for calculating at
least one changing value of the output data values of said measuring means
on the basis of the read-out output data value and an output data value
stored at a current time point from said measuring means to thereby
calculate the estimation value on the basis of the output data value
stored at the current time point and the changing value, means for reading
out output data values stored in said memory means one and two periods
before and for calculating the estimation value on the basis of the
read-out output data values and the output data value stored at the
current time point, and means for calculating a first difference value
between the output data value stored at the current time point and the
output data value stored one period before, a second difference between
the output data values stored one and two periods before, and a third
difference value between the first and second difference values and for
calculating the sum of the output data value stored at the current time
point and a difference value between the first and third difference values
to thereby obtain an estimation value.
25. A method of controlling a controllable device mounted on an automobile
which has measuring means for measuring a data value representing at least
one state of said controllable device mounted on the automobile, memory
means for storing successive output data values of said measuring means
and operation processing means for calculating at least one control value
to be applied to said controllable device on the basis of output data
values of said measuring means, comprising:
a first step of reading out at least one output data value previously
stored in said memory means;
a second step of calculating at a current time point an estimation value
representing said one state of said controllable device at a future time
point on the basis of an output data value of said measuring means at a
current time point and the output data value read out from said memory
means;
a third step of calculating in said operation processing means the control
value on the basis of the estimation value and for applying a control
signal representing the control value to said controllable device; and
a fourth step of storing successive output data values received
periodically from said measuring means in said memory means; wherein
said second step reads out at least one output data value previously stored
in said memory means, calculates at least one changing value of the output
data values of said measuring means on the basis of the read-out output
data value and an output data value stored at a current time point from
said measuring means, to thereby calculate the estimation value on the
basis of the output data value stored at the current time point and the
changing value, reads out output data values stored in said memory means
one and two periods before, calculates the estimation value on the basis
of the read-out output data values and the output data value stored at the
current time point, calculates a first difference value between the output
data value stored at the current time point and the output data value
stored one period before, a second difference between the output data
values stored one and two periods before, and a third difference value
between the first and second difference values, and calculates the sum of
the output data value stored at the current time point and a difference
value between the first and third difference values to thereby obtain an
estimation value representing said state at one period after.
26. A method of controlling a controllable device mounted on an automobile
which has measuring means for measuring a data value representing at least
one state of said controllable device mounted on the automobile, emory
means for storing successive output data values of said measuring means
and operation processing means for calculating at least one control value
to be applied to said controllable device on the basis of output data
values of said measuring means, comprising:
a first step of reading out at least one output data value previously
stored in said memory means;
a second step of calculating at a current time point an estimation value
representing said one state of said controllable device at a future time
point on the basis of an output data value of said measuring means at a
current time point and the output data value read out from said memory
means;
a third step of calculating in said operation processing means the control
value on the basis of the estimation value and for applying a control
signal representing the control value to said controllable device; and
a fourth step of storing successive output data values received
periodically from said measuring means in said memory means and storing a
coefficient proportional to a time constant of a step response of said
measuring means; and wherein
said second step reads out at least one output data value previously stored
in said memory means and calculates at least one changing value of the
output data values of said measuring means on the basis of the read-out
output data value and an output data value stored at a current time point
from said measuring means to thereby calculate the estimation value on the
basis of the coefficient, the output value stored at current time point
and the changing value.
27. A method of controlling a controllable device mounted on an automobile
which has measuring means for measuring a data value representing at least
one state of said controllable device mounted on the automobile, memory
means for storing successive output data values of said measuring means
and operation processing means for calculating at least one control value
to be applied to said controllable device on the basis of output data
values of said measuring means, comprising:
a first step of reading out at least one output data value previously
stored in said memory means;
a second step of calculating at a current time point an estimation value
representing said one state of said controllable device at a future time
point on the basis of an output data value of said measuring means at a
current time point and the output data value read out from said memory
means;
a third step of calculating in said operation processing means the control
value on the basis of the estimation value and for applying a control
signal representing the control value to said controllable device; and
a fourth step of detecting a data value representing at least another state
of the controllable device;
a fifth step of generating at least one value produced from a function
representing the state of the controllable device on the basis of the
detection data value of the detecting means; and
a sixth step of storing successive output data values received periodically
from said measuring means into said memory means; wherein
said second step reads out at least one output data value previously stored
in said memory means and calculates at least one changing value of the
output data values of said measuring means on the basis of the read-out
output data value and an output data value stored at a current time point
from said measuring means to thereby calculate the estimation value on the
basis of the output data value stored at the current time point, the
changing value, and the value produced from the function. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
The present invention relates to an electric control apparatus for
processing data measured with various sensors and controlling an engine
and/or suspension of an automobile on the basis of the processed data, and
more particularly to an apparatus for and method of compensating for a
time delay of measured data.
In a conventional electric control apparatus for an engine and/or
suspension of a vehicle, such as an automobile, data measured with various
sensors is picked up at an interval of a constant time or constant rotary
angle (i.e., rotary angle of the crank shaft), and the picked up data is
averaged, e.g., by means of weighted averaging, within a predetermined
section (e.g., within a predetermined time duration or predetermined
rotary angle range), and is processed for removal of noises by means of a
primary delay filter or the like, to effect smoothing of pulsation of
suction air to the engine, and to other processings. The electric control
apparatus of this type is disclosed in, e.g., Japanese Patent Laid-open
Publication JP-A-58-8239.
The engine conditions of an automobile change from time to time while
measuring engine running data. Therefore, it becomes necessary to control
fuel injection, ignition advance angle and the like in order to deal with
such a change, especially a rapid change of the engine conditions.
However, the control operation will be delayed due to a time delay at a
filter used for noise removal, a time delay at a sensor while converting a
physical value into an electrical value, and a time delay required for
processing data at the electrical control apparatus of is automobile.
Such a delay in the control operation will be described with reference to
FIGS. 1 and 2. FIG. 1 is a graph showing a relationship between a throttle
opening angle (degree) of a throttle valve and a flow rate Q of suction
air to the engine, and FIG. 2 is a graph showing the control
characteristic of an air/fuel ratio of a gas mixture in the engine when
rapidly opening the throttle valve under control of a conventional control
apparatus.
FIG. 1 shows a characteristic curve (a) of measured data obtained when
rapidly opening a throttle valve as shown by a curve (c), wherein the flow
rate of suction air to the engine is measured with an air flow sensor,
such as a hot-wire type air flow meter, and the measured data is passed
through a filter, such as an RC circuit, in the manner as will be
described later and thereafter A/D converted. A curve (b) represents an
actual flow rate of suction air to the engine. It is to be noted that the
measured data exhibits a delay from the actual flow rate because of a
delay in the air flow meter, RC circuit and the like. Therefore, if a fuel
corresponding in amount to an air flow rate measured at the time of rapid
opening of the throttle valve is injected for the purpose of obtaining a
target air/fuel ratio, e.g., of 14.7, the resultant air/fuel ratio takes a
value shifted from the target value 14.7 as shown in FIG. 2 because of a
delay of the measured air flow rate. Therefore, there arises the
phenomenon that the air flow rate becomes lean at the start of
acceleration (at the time of increasing the air flow rate), whereas it
becomes rich during a short period at the end of acceleration.
As described above, there arises the problem that a correct control cannot
be ensured during a rapid engine condition change if actuators (e.g., the
fuel injection valve and the like) are controlled in accordance with
manipulatory values calculated based on the averaged or smoothed, measured
data.
As disclosed in Japanese Patent Laid-open Publications JP-A-63-131840 and
JP-A-63-131841, in an engine control apparatus which calculates a fuel
injection time on the basis of an output from a pressure sensor for
measuring the pressure in an intake tube, the pulsation component of a
pressure output signal from the pressure sensor is removed with a filter
having a relatively large time constant. In order to compensate for a
delay of the fuel injection control caused by a delay of the measured
pressure data, a reference fuel injection time duration at a current time
point is adjusted based on a difference between the reference fuel
injection time duration at the current time point and the reference fuel
injection time duration calculated one period earlier, and based on other
parameters. A fuel injection time duration is calculated based on the data
supplied from a plurality of sensors, such as pressure sensor data, engine
revolution number data and the like. However, this control apparatus
operates to compensate for a time delay not of the respective measured
data, but of the final manipulatory value. Therefore, the control
apparatus cannot satisfactorily follow a rapid change in output data from
respective sensors so that the delays in measured data cannot be correctly
compensated. For example, in the case where only the pressure in the
intake valve changes and the engine rotation number does not change, it is
not possible to compensate for the measured pressure data only.
Consequently, a correct engine control is not possible leading to a
hardship of proper engine output control and exhaust gas control.
Further, there is not known a conventional electric control apparatus for a
suspension which can compensate for a delay of measured data from a dumper
stroke sensor or the like, resulting in a hardship of correctly
controlling a suspension upon a rapid change of road conditions.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of and
apparatus for compensating for a time delay of data measured with various
sensors, in an electric control apparatus for an engine and/or suspension
of a vehicle such as an automobile.
The above object is achieved, in an electric control apparatus for
controlling a controllable device such as an engine, suspension, etc.
based on the results of processing data measured with various sensors, by
passing the data measured with sensors through a phase advance (lead)
filter prior to the data processing to compensate the measured data itself
for a time delay.
A phase advance filter as proposed by the present invention compensates for
a delay time, i.e., a time required for processing data after the time
when a sensor has measured the data. Specifically, as will be described in
connection with various embodiments, the phase advance filter obtains an
estimation value for a correct sensor output value at a current time point
(or at a current rotary angle position) through calculation of measured
data at past time points and the current point. For instance, the
estimation value at the current time point (or at the current rotary angle
position) is a sum of the measured value at the current time point (or at
the current rotary angle position) and a difference between the measured
values at the current time point and at the time point one period earlier.
The term "period" means a constant time duration or constant rotary angle
range, at an interval of which data is picked up. In other words, in
accordance with the present invention, a time delay of measured data is
compensated by calculating an estimation value of data to be measured at
the time point after one period based on the data measured at the current
and past time points, and by regarding the calculated estimation value as
an actual measured data value at the current time point.
According to another method of calculating an estimation value at a current
time point (or at a current rotary angular position), a difference between
the measured data values at the current time point (or at the current
rotary angular position) and at one period earlier is multiplied by a
coefficient derived by using a function of another measured data value,
such as an engine revolution number, and the resultant data value is added
to the measured data value at the current time point (at the current
rotary angular position).
An estimation value thus obtained is substantially equal to the correct
sensor output value at the current time point (rotary angular position).
An engine and/or suspension is controlled based on the estimation value so
that a correct control with good response to a rapid change in engine
running conditions and/or road conditions is ensured to thereby improve
the engine output characteristic, exhaust gas characteristic and the like.
The measured data may preferably be passed through a phase advance filter
only at a transition state of the engine or suspension. Similarly, the
measured data may be passed through a phase advance filter only when a
change in measured data value increases at a rate larger than or equal to
a predetermined rate. With such arrangements, a more correct estimation
value can be obtained for various conditions on an engine, suspension, and
other vehicle systems.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing a relationship between a throttle valve opening
angle and a measured air flow rate according to the prior art;
FIG. 2 is a graph showing an air/fuel control characteristic associated
with FIG. 1;
FIG. 3 is a schematic diagram showing the main part of an internal
combustion engine of an automobile to which the present invention is
applied;
FIG. 4 is a schematic block diagram of the control unit of FIG. 3;
FIG. 5 shows an example of an RC filter;
FIG. 6 is a graph showing a response characteristic of an RC filter;
FIG. 7 is a graph showing a relationship between a throttle opening angle
and an estimation value of air flow rate data, according to a first
embodiment of this invention;
FIG. 8 shows an air/fuel control characteristic associated with FIG. 7;
FIG. 9A is a flow chart for illustrating the operation of the first
embodiment;
FIG. 9B is a diagram for explaining the data shift operation of the first
embodiment;
FIGS. 10 and 11 are schematic diagrams of the delay compensation circuit
according to the first embodiment;
FIG. 12 is a graph showing the characteristic of an estimation value of air
flow rate data, according to a second embodiment of this invention;
FIG. 13 is a schematic diagram of a delay compensation circuit according to
the second embodiment;
FIG. 14 is a block diagram showing a third embodiment;
FIG. 15 is a block diagram showing a modification of the third embodiment;
FIG. 16 is a schematic diagram of a circuit according to a fourth
embodiment of this invention;
FIG. 17 is a diagram showing the characteristic of measured data of a
stepwise changing air flow rate;
FIGS. 18A to 18D show the examples of maps used in a fifth embodiment of
this invention;
FIG. 19 is a schematic diagram of a circuit according to a fifth embodiment
of this invention;
FIG. 20 is a schematic diagram of a circuit according to a sixth embodiment
of this invention;
FIG. 21 is a flow chart used for explaining the operation of the sixth
embodiment; and
FIG. 22 is a schematic diagram of representing a circuit of a modification
of the sixth embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The embodiments of the present invention will be described with reference
to the accompanying drawings. FIG. 3 shows a fuel injection system and the
like of an internal combustion engine of an automobile to which the
present invention is applied.
In FIGS. 3, air enters from an air cleaner 1, passes through an air flow
meter, such as a hot-wire type air flow meter (also called an air flow
sensor) 91, a throttle valve 2, and a bypass air valve 3, and reaches an
injector 5. At the injector 5, fuel supplied from a fuel tank 13 via a
fuel pump 14 is injected and mixed with air to be sucked into the
combustion chamber. In the combustion chamber, the gas mixture is ignited
by an ignition plug and burned. The burning gas passes through an exhaust
tube 12 and the air/fuel ratio thereof is measured by an air/fuel ratio
sensor 8.
Inputted to a control unit 10 is a signal representative of a suction air
flow rate from the air flow meter 91, a signal representative of an
air/fuel ratio from the air/fuel ratio sensor 8, a signal representative
of the temperature of cooling water from a cooling water temperature
sensor 4, a pulse signal outputted from a distributor crank angle sensor 6
every time a crank shaft (not shown) rotates by a predetermined angle, and
other signals.
The structure of the control unit 10 is shown in FIG. 4. Devices to be
controlled by the control unit 10 include an engine, suspension and the
like. Outputs from various sensors mounted on an automobile can be used
therefore as the measured data which is subjected to delay compensation
according to this invention. In addition to the outputs from the
above-described sensors, the control unit 10 may be connected to receive,
as shown in FIG. 4, an output signal from a throttle angle sensor 92 for
measuring an angular position .theta.th of the throttle valve, and an
output from a dumper stroke sensor 15 for measuring the dumper stroke
position of a wheel on the suspension. These outputs from the sensors 4,
6, 8, 15, 91 and 92 represent data indicative of the conditions of the
controllable devices. In addition, inputted to the control unit 10 are
output signals from an idle switch 16 and starter switch 17, and an output
signal from a battery voltage sensor 18. The control unit 10 includes an
input/output circuit (simply called an I/O circuit hereinafter) 26 for
receiving the outputs from the sensors, a microprocessor unit (called an
MPU hereinafter) 20, a read-only memory (called ROM hereinafter) 22, and a
random access memory (called RAM hereinafter) 24. In the I/O circuit, the
analog outputs from, e.g., the air flow sensor 91, air/fuel ratio sensor
8, dumper stroke sensor 15, throttle angle sensor 92 and etc. are sent to
a multiplexer 36 via corresponding primary delay filters 30, 32, 34 and 31
in the form of, e.g., an RC filter for removing signal noises. The
multiplexer sequentially selects and sends the inputted signals to an A/D
converter 38 at a predetermined period (e.g., predetermined time duration
or predetermined rotary angle range). The A/D converted digital data is
stored in RAM 24 and is processed by MPU 20.
An example of the RC filter circuit is shown in FIG. 5, and the step
response characteristic thereof is shown in FIG. 6.
FIG. 6 shows an output voltage from the RC filter circuit when a stepwise
voltage (a signal representative of an air flow rate) from the air flow
sensor 91 is inputted to the RC filter circuit.
A pulse signal from the crank angle sensor 6 passes through the I/O circuit
and is counted, e.g., with a soft counter in RAM 24 to thereby calculate a
revolution number of the engine per unit time. The revolution number is
stored at a predetermined period in RAM at a predetermined area. Other
input signals are processed in a similar manner.
Respective data stored in RAM are subjected to predefined operations, such
as calculation for a fuel injection pulse width, ignition timing, dumper
stroke position and the like, in accordance with program instructions
stored in ROM. The operation results are outputted as commands to the I/O
circuit, which in turn outputs control signals to the actuators so that
the actuators control the controllable devices, such as the fuel injection
valve 5, ignition coil 7, oil pressure control device 19 for controlling
the dumper stroke position, and the like.
The main reason for the deterioration of the air/fuel ratio control
characteristic of the control apparatus as shown in FIG. 2 is a time delay
from the time when a sensor has measured a data value to the time when MPU
20 processes the data. This time delay is caused by a delay at the sensor
itself, a delay at a primary delay filter, a delay at the A/D converter,
and the like. For instance, a delay of about 10 to 30 msec is present at
an air flow sensor, several tens of msec delay is added at an RC fil | | |
