JPH116460A - Air amount detecting device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine a fundamental fuel injection amount, corresponding to a cylinder suction air amount, rapidly and high precisely during starting. SOLUTION: Between a first reference signal REF and a second reference signal REF from a crank angle sensor during starting, an integrating value SQ of a suction air flow rate Q is determined (S6). Based on the integrating value, a fundamental fuel injection amount TP corresponding to an initial value of a cylinder intake air amount is calculated (S9). A calculated result forms an initial value and the fundamental fuel injection amount TP corresponding to a cylinder intake air amount is calculated (S10-S12) through smoothing processing by a weighted mean.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the amount of air in an internal combustion engine, and more particularly to a technique for detecting the amount of air taken into a cylinder at the time of starting.

[0002]

2. Description of the Related Art In a conventional air amount detecting device for an internal combustion engine, an air flow meter (air flow meter) is provided in an engine intake passage.
At the time of startup, a raw air flow rate signal is used, and when a complete explosion and rotation increase, the cylinder intake air amount is obtained by smoothing processing such as a weighted average (JP-A-8-144834).
Reference).

[0003]

However, in such a conventional air amount detecting device for an internal combustion engine, the raw air flow rate signal used at the time of starting has a large output fluctuation due to intake pulsation. When the fuel ratio is controlled, the air-fuel ratio fluctuates greatly. Further, since the cylinder intake air amount cannot be obtained until the complete explosion, the control accuracy of the air-fuel ratio is poor.

On the other hand, it is conceivable to perform a smoothing process such as a weighted average from the beginning, but it is difficult to set an initial value, and if the start is zero, the delay of the weighted average becomes extremely large. Therefore, the accuracy of the required value is low (see FIG. 4). The present invention has been made in view of such conventional problems,
It is an object of the present invention to provide an air amount detection device for an internal combustion engine, which can quickly and accurately obtain a cylinder intake air amount at the time of starting, thereby improving control accuracy such as an air-fuel ratio.

[0005]

Therefore, in the invention according to the first aspect, as shown in FIG. 1, in an air amount detecting device for an internal combustion engine having an air flow meter in an engine intake passage, a predetermined initial start-up time is determined. A starting initial section determining means for determining a predetermined crank angle section; an integral value calculating means for calculating an integrated value of an intake air flow rate (Q) detected by the air flow meter in the predetermined crank angle section; After the lapse of the angular section, the smoothing process for calculating the cylinder intake air amount (Qcyl) by smoothing the intake air amount per unit rotation based on the detection value of the air flow meter using the integral value as an initial value. Means,
Is provided.

In the invention according to claim 2, the starting initial section determining means includes a section between the reference signals output from the crank angle sensor at a reference crank angle position in synchronization with the engine rotation as the predetermined crank angle section. Is determined. In the invention according to claim 3, the starting initial section determining means determines that the predetermined crank angle section is
It is characterized in that a section from the start of starting to the first reference signal output at the reference crank angle position in synchronization with the engine rotation from the crank angle sensor is determined.

In the invention according to a fourth aspect, the starting initial section discriminating means outputs the predetermined crank angle section from the start of the starting operation at a reference crank angle position synchronized with the engine rotation from the start of the crank angle sensor. The section up to the reference signal is determined, but when the crank angle of the determined section is less than a predetermined angle, the section has a section changing means for changing the predetermined crank angle section to a section between the reference signals. It is characterized by being.

[0008] In the invention according to claim 5, the integral value calculating means is provided in a section from the start of starting to the first reference signal.
A means for calculating an integrated value of the intake air flow rate detected at a constant sampling time interval by the air flow meter, wherein the integrated value is corrected by a correction coefficient obtained from a crank angle of the section. It is characterized by being.

[0009] In the invention according to claim 6, the smoothing processing means uses the integral value as an initial value, and performs a weighted average of an intake air amount per unit rotation based on a detection value of the air flow meter, thereby obtaining a cylinder suction amount. It is characterized by calculating the amount of air. The invention according to claim 7 is characterized in that switching means for providing a preset value as the cylinder intake air amount is provided until the cylinder intake air amount is first calculated by the smoothing processing means. (See FIG. 1).

[0010]

According to the first aspect of the present invention, an integrated value of the intake air flow rate detected by the air flow meter is calculated in a predetermined crank angle section at a predetermined initial stage of starting, and this is set as an initial value. Since the cylinder intake air amount is calculated by smoothing processing such as weighted averaging, the cylinder intake air amount can be quickly and accurately obtained at the time of start-up, thereby improving the control accuracy of the air-fuel ratio and the like, and thus reducing the atmospheric pressure. Even if the temperature or the temperature changes, good starting can be performed.

According to the second aspect of the present invention, the predetermined crank angle section is defined as a section between reference signals (constant crank angle).
By doing so, the initial value of the smoothing process can be obtained with high accuracy. According to the third aspect of the present invention, the initial value of the smoothing process can be obtained very quickly by setting the predetermined crank angle section as a section from the start of starting to the first reference signal.

According to the present invention, the predetermined crank angle section is a section from the start of starting to the first reference signal. If the crank angle in that section is smaller than the predetermined angle, the predetermined crank angle section is set. Since the section is changed to the section between the reference signals, both the speed of obtaining the initial value of the smoothing process and the accuracy can be achieved. According to the invention according to claim 5, when calculating the integrated value of the intake air flow rate in a section from the start of starting to the first reference signal, the integrated value is
By correcting with the correction coefficient obtained from the crank angle in the section, it is possible to improve the accuracy while securing the speed of obtaining the initial value of the smoothing process.

According to the sixth aspect of the present invention, by employing a weighted average as the smoothing processing, the processing can be performed more easily than when a manifold model or the like is used. According to the seventh aspect of the present invention, the minimum control can be secured by providing the set value until the cylinder intake air amount is first calculated by the smoothing process.

[0014]

Embodiments of the present invention will be described below. FIG. 2 shows a system diagram of the internal combustion engine. The air from the air cleaner 1 is sucked into the throttle chamber 2 under the control of a throttle valve 3 substantially linked to an accelerator pedal (not shown). Then, at a branch portion of the intake manifold 4, the fuel is mixed with fuel injected from a fuel injection valve 5 provided for each cylinder to form an engine 6.
Is sucked into the cylinder.

The fuel injection valve 5 is an electromagnetic fuel injection valve that is energized by an electromagnetic coil, is opened, is de-energized, and is closed, and is energized by a drive pulse signal from the control unit 10 to open. The fuel which is pressure-fed by a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator is injected. The fuel injection valve 5 may be provided so as to directly inject fuel into each combustion chamber of the engine 6.

The control unit 10 receives signals from various sensors for controlling fuel injection. As the various sensors, for example, a hot wire air flow meter (air flow meter) 11 is provided upstream of the throttle valve 3 and outputs a voltage signal corresponding to the intake air flow rate Q.

A crank angle sensor 12 is provided.
In the case of a cylinder, a reference signal REF is output at a reference crank angle position at every 180 ° crank angle,
The unit signal POS is output every °. Here, the engine speed Ne can be calculated from the cycle of the reference signal REF and the like.
In addition, a water temperature sensor 13 for detecting an engine cooling water temperature Tw, a throttle sensor 14 for detecting a throttle opening TVO, an oxygen sensor 15 for detecting an air-fuel ratio rich / lean from an oxygen concentration in exhaust gas, a start switch 16, etc. Is provided.

Here, the control unit 10
3 or 5 by a built-in microcomputer.
The basic fuel injection amount TP corresponding to the cylinder intake air amount is determined by performing calculation processing according to the basic fuel injection amount calculation routine shown in the flowchart of FIG. This is further corrected to determine the final fuel injection amount TI.
The fuel injection is performed by outputting a drive pulse signal having a pulse width of I to the fuel injector 5 at a predetermined timing synchronized with the engine rotation.

First, a description will be given of a basic fuel injection amount calculation routine of the first embodiment shown in FIG. This example is
From the first reference signal REF to the second reference signal REF from the crank angle sensor 12, an integrated value (integrated value) of the intake air flow rate is obtained, and this is set as an initial value.
The basic fuel injection amount corresponding to the cylinder intake air amount is obtained by a weighted average process.

The routine of FIG. 3 is executed for a predetermined time Δt (for example, 2
ms). In another routine, the reference signal RE from the crank angle sensor 12 is used as a REF number counter.
The number of occurrences of F is counted. Step 1 (S in the figure)
Marked as 1. The same applies to the following).
A / D-converts and reads the output voltage.

In step 2, the read value is linearized to detect the intake air flow rate Q. Step 3
Then, referring to the REF number counter, it is determined whether or not REF number ≧ 2. If the number of REFs is not equal to or more than 2, the process proceeds to step 4 to determine whether or not the number of REFs = 1.

If the number of REFs is not 1, since the first reference signal REF has not been issued since the start of the engine, the routine proceeds to step 5, where the integrated value (integrated value) S of the intake air flow rate is calculated.
Set Q = 0. Then, the routine proceeds to step 7, where the basic fuel injection amount TP is set to INTP # (set value), and this routine is terminated. When the number of REFs = 1, it is between the first reference signal REF and the second reference signal REF, and in this embodiment, it is a predetermined crank angle section at the beginning of the start for obtaining an integrated value of the intake air flow rate. Therefore, the process proceeds to step 6 where the intake air flow rate Q is integrated and the integrated value SQ is updated (SQ = SQ + Q; see FIG. 4). Then, the routine proceeds to step 7, where the basic fuel injection amount TP is set to INTP # (set value), and this routine is terminated.

After the second reference signal REF is issued, it is determined in step 3 that the number of REFs ≧ 2.
Proceed to step 8. In step 8, it is determined whether or not the number of REFs ≧ 2, and it is the first time. In the case of the first time, since it is the timing for obtaining the integral value of the intake air flow rate between the reference signals REF, the process proceeds to step 9.

In step 9, the integral value SQ of the intake air flow rate between the reference signals REF is multiplied by a constant K2 # to obtain a basic fuel injection amount TP = S corresponding to the initial value of the cylinder intake air amount.
Q × K2 # is calculated, and this routine ends. When the sampling time interval Δt is changed, the constant K2 # is changed accordingly. If not, step 10
Proceed to ~ 12.

In step 10, based on the raw intake air flow rate Q, the basic fuel injection amount RTP corresponding to the intake air amount per unit rotation = (Q / Ne) × K # (Ne is the engine speed, K # Is a constant). In step 11, a weighted average weighting constant FLOAD (0 <FLOAD <1) is calculated by the following equation.

FLOAD = 1 / [(120 × Vm) / (V
e × η × Ne × Δt) +1] Vm: intake manifold volume (cc) Ve: displacement (cc) η: intake charging efficiency Ne: engine speed (rpm) Δt: calculation time interval (s).

In step 12, a smoothing process by weighted averaging is performed. That is, according to the following equation, the basic fuel injection amount RTP corresponding to the intake air amount per unit rotation based on the raw intake air flow rate, and the basic fuel injection amount TP corresponding to the initial value or the previous value of the cylinder intake air amount. Based on the weighted average, the basic fuel injection amount TP corresponding to the cylinder intake air amount
Is updated, and this routine ends.

TP = RTP × FLOAD + TP × (1−FLOAD) Here, Steps 3 and 4 correspond to the starting initial section determining means, Steps 6 and 9 correspond to the integral value calculating means, and Step 10 The parts of ~ 12 correspond to the smoothing processing means. Step 7 corresponds to switching means. As described above, in this embodiment, as shown in FIG. 4, the integrated value (integral value) of the intake air flow rate between the first reference signal REF from the crank angle sensor 12 and the second reference signal REF. ) SQ is determined, and this is set as an initial value (a). Then, a basic fuel injection amount TP corresponding to the cylinder intake air amount Qcyl is determined by a weighted average process.
The basic fuel injection amount corresponding to the cylinder intake air amount can be quickly and accurately obtained at the start of the engine, and the control accuracy such as the air-fuel ratio can be increased. Will be able to do it.

On the other hand, as in the prior art, the initial value of the weighted average =
In the case of 0, the delay of the weighted average becomes extremely large, and in the case of the initial value = predetermined value, the request for the predetermined value is greatly different depending on the atmospheric pressure and the temperature. It is. (See FIG. 4). In this embodiment, the first reference signal REF from the crank angle sensor 12 is used.
From the first reference signal REF to the third reference signal REF, the integrated value (integral value) SQ of the intake air flow rate is calculated between the first reference signal REF and the third reference signal REF. The period may be before the reference signal REF. ,next,
A description will be given of a basic fuel injection amount calculation routine of FIG. 5 which is a second embodiment. In this embodiment, basically, from the start of starting (start switch ON), the crank angle sensor 12
, The integrated value (integrated value) of the intake air flow rate is obtained from the time until the first reference signal REF, and this is set as an initial value. It is what we asked for.

The routine shown in FIG. 5 is executed for a predetermined time Δt (for example, 2
ms). In another routine, a crank angle sensor is used as a REF number counter and a POS number counter.
The number of occurrences of the reference signal REF and the unit signal POS from 12 are counted. In step 21, the output voltage of the air flow meter 11 is A / D converted and read. In step 22, the read value is linearized to detect the intake air flow rate Q.

In step 23, it is determined whether or not REF number ≧ 1 by referring to the REF number counter. If the REF number is not equal to or more than 1, it is before the first reference signal REF is issued from the start of the start, and in this embodiment, it is a predetermined crank angle section at the initial stage of the start for obtaining the integral value of the intake air flow rate. Then, the intake air flow rate Q is integrated, and the integrated value SQ is updated (SQ = SQ + Q; see FIG. 6). Then, the routine proceeds to step 25, where the basic fuel injection amount TP = INT
P # (set value) is set, and this routine ends.

After the first reference signal REF is issued,
Since it is determined in step 23 that the REF number ≧ 1, the process proceeds to step 26. In step 26, the number of REFs is equal to or more than 1, and it is determined whether or not it is the first time. In the case of the first time, the process proceeds to step 27 because it is the timing for obtaining the integral value of the intake air flow rate from the start of the start to the first reference signal REF.

In step 27, the POS number (the crank angle x ° rotated from the start of the start to the first reference signal REF) is read with reference to the POS number counter. In step 28, it is determined whether or not the number of POS <predetermined value (for example, 80 ° in crank angle). If the POS number is not smaller than the predetermined value, the process proceeds to step 30, and the correction coefficient Y is obtained from the POS number (x °) with reference to the table of FIG. FIG. 7 shows a case of four cylinders, and when x = 180 °, the correction coefficient Y = 1.
The correction coefficient Y increases as x decreases.

In step 31, the integrated value SQ of the intake air flow rate is multiplied by the correction coefficient Y and further multiplied by a constant K2 # to obtain the basic fuel injection amount TP = SQ × Y corresponding to the initial value of the cylinder intake air amount. × K2 # is calculated, and this routine ends. If it is not the first time, proceed to steps 32 to 34. In step 32, based on the raw intake air flow rate Q, the basic fuel injection amount RTP corresponding to the intake air amount per unit rotation
= (Q / Ne) × K # (Ne is the engine speed, K # is a constant).

At step 33, a weighted average weighting constant FLOAD (0 <FLOAD <1) is calculated (similar to step 11 described above). In step 34, a smoothing process using a weighted average is performed. That is, according to the following equation, the basic fuel injection amount RTP corresponding to the intake air amount per unit rotation based on the raw intake air flow rate, and the basic fuel injection amount TP corresponding to the initial value or the previous value of the cylinder intake air amount. The basic fuel injection amount TP corresponding to the cylinder intake air amount is updated by the weighted average, and this routine ends.

TP = RTP × FLOAD + TP × (1−FLOAD) On the other hand, if it is determined in step 28 that the number of POS <predetermined value, the process proceeds to step 29. In step 29, the integrated value SQ of the intake air flow rate is cleared, and the REF number counter and the POS number counter are cleared. And step 25
Then, the basic fuel injection amount TP is set to INTP # (set value), and the routine ends.

Therefore, even after the first reference signal REF is actually issued, since the number of REFs is less than 1 in the determination at step 23, the process proceeds to step 24, at which the intake air flow rate Q is integrated and integrated. Update the value SQ (SQ = SQ + Q; FIG. 6)
Dotted line). Then, in step 25, the basic fuel injection amount TP is set to INTP # (initial value), and the routine ends.

Then, when the second reference signal REF is actually generated, the number of REFs ≧≧
Therefore, at this time, the process proceeds to step 31 via steps 26, 27, 28, and 30, and the correction coefficient Y is added to the integrated value SQ of the intake air flow rate (where x = 180 °,
Y = 1), and further multiplied by a constant K2 # to obtain a basic fuel injection amount TP = SQ corresponding to the initial value of the cylinder intake air amount.
× Y × K2 # is calculated, and this routine ends.

Thereafter, the program proceeds to steps 32 to 34, in which a basic fuel injection amount TP corresponding to the cylinder intake air amount is obtained by a smoothing process using a weighted average. Here, the step 23 corresponds to the starting initial section determining means, and the steps 24 and 31 correspond to the integral value calculating means.
32 to 34 correspond to the smoothing processing means. Step 25 corresponds to the switching means. Step 27
29 correspond to the section changing means, and the steps 30 and 31 correspond to the correcting means.

As described above, in this embodiment, the integrated value (integrated value) SQ of the intake air flow rate is obtained from the start of start (start switch ON) to the first reference signal REF.
With this as an initial value, after that, by weighted average processing,
Basic fuel injection amount T corresponding to cylinder intake air amount Qcyl
Since P is obtained, the basic fuel injection amount corresponding to the cylinder intake air amount can be obtained very quickly at the time of starting.

If the section from the start of starting to the first reference signal is smaller than the predetermined angle (dotted line in FIG. 6), the accuracy deteriorates. Therefore, the section is changed to the section between the reference signals and the initial value is obtained. In addition, the speed and accuracy of obtaining the initial value of the smoothing process can be compatible. Note that the final fuel injection amount TI is calculated by the following equation, for example. TI = TP × Tfbya × (α + αm) + Chosn + TS Tfbya is various correction coefficients including target air-fuel ratio correction, water temperature increase, acceleration increase, etc., α is an air-fuel ratio feedback correction coefficient based on a signal from the oxygen sensor 15, and αm is air-fuel ratio feedback. The learning correction coefficient learned from the correction coefficient α, TS, is a voltage correction based on the battery voltage.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention.

FIG. 2 is a system diagram of an internal combustion engine showing an embodiment of the present invention.

FIG. 3 is a flowchart of a first embodiment.

FIG. 4 is a characteristic diagram of the first embodiment.

FIG. 5 is a flowchart of a second embodiment.

FIG. 6 is a characteristic diagram of the second embodiment.

FIG. 7 shows a correction coefficient table.

[Explanation of symbols]

 3 Throttle valve 5 Fuel injection valve 6 Engine 10 Control unit 11 Air flow meter 12 Crank angle sensor

Claims (7)

[Claims] 1. An air amount detection device for an internal combustion engine having an air flow meter in an engine intake passage, comprising: a starting initial section discriminating means for discriminating a predetermined initial crank angle section at an initial start; An integrated value calculating means for calculating an integrated value of the intake air flow rate detected by the air flow meter; and after the elapse of the predetermined crank angle section, the integrated value is set as an initial value, and a unit rotation per unit rotation based on the detected value of the air flow meter is performed. By smoothing the intake air amount of
An air amount detection device for an internal combustion engine, comprising: smoothing processing means for calculating a cylinder intake air amount. 2. The starting initial section discriminating means discriminates, as the predetermined crank angle section, a section between reference signals output from a crank angle sensor at a reference crank angle position in synchronization with engine rotation. 2. The method according to claim 1, wherein
An air amount detection device for an internal combustion engine according to claim 1. 3. The starting initial section discriminating means, as the predetermined crank angle section, a section from the start of starting to a first reference signal output from a crank angle sensor at a reference crank angle position in synchronization with engine rotation. The air amount detection device for an internal combustion engine according to claim 1, wherein the air amount detection device is configured to determine the air amount. 4. The starting initial section discriminating means, as the predetermined crank angle section, a section from the start of starting to a first reference signal output from a crank angle sensor at a reference crank angle position in synchronization with engine rotation. When the crank angle of the determined section is smaller than a predetermined angle, a section changing means for changing the predetermined crank angle section to a section between reference signals is provided. The air amount detection device for an internal combustion engine according to claim 1. 5. An integrated value calculating means for calculating an integrated value of an intake air flow rate detected at a constant sampling time interval by the air flow meter in a section from a start of starting to a first reference signal. 5. The air amount detection device for an internal combustion engine according to claim 3, further comprising a correction unit that corrects the integrated value with a correction coefficient obtained from a crank angle of the section. 6. The smoothing means calculates a cylinder intake air amount by using the integral value as an initial value and performing a weighted average of an intake air amount per unit rotation based on a detection value of the air flow meter. The air amount detection device for an internal combustion engine according to any one of claims 1 to 5, characterized in that: 7. A switching means for providing a predetermined set value as a cylinder intake air amount until the cylinder intake air amount is first calculated by the smoothing processing means. An air amount detection device for an internal combustion engine according to any one of claims 6 to 6.