JPH05264313A - Device for detecting intake air quantity of internal combustion engine - Google Patents

Abstract

PURPOSE:To accurately detect the intake air quantity of an internal combustion engine irrespective of the output varying state of an air flowmeter, whether in a transient state or pulsating state, by discriminating the varying state and correcting the intake air quantity only when the varying state is in the pulsating state. CONSTITUTION:When the output varying state of an air flowmeter 16 is in a pulsating state, an electronic control circuit 18 calculates the maximum and minimum values and ripple factor of a tentative air quantity. Then the circuit 18 reads the rotating speed of an internal combustion engine 11 from the signal of a rotational angle sensor 19. An actual intake air quantity can be obtained by reading out the correcting amount corresponding to the ripple factor and rotating speed and correcting the tentative air quantity by using the correcting amount. Thus a tentative air quantity which well coincidents with the actual intake air quantity can be obtained by correcting the tentative air quantity when the varying state is in the pulsating state in which the tentative air quantity found from the output of the flowmeter 16 does not coincide with the actual intake air quantity. When the varying state is in a transient state in which the tentative air quantity well coincides with the actual air quantity, such correction is not required. Therefore, the intake air quantity can be accurately detected irrespective of the varying state, whether in the pulsating state or transient state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air amount detecting device for an internal combustion engine which detects an intake air amount using a hot wire type air flow meter.

[0002]

2. Description of the Related Art Conventionally, as a device for detecting an intake air amount of an internal combustion engine, a device using a hot wire type air flow meter is well known. This is equipped with an energizing heat generating part in the intake pipe,
The energization amount is controlled so that the energization heat generating portion is maintained at a predetermined temperature, or the energization amount is controlled so that the heat generation amount becomes a predetermined amount. Since the amount of heat radiated from the energizing heat generating portion corresponds to the amount of intake air, the amount of intake air can be detected by the energization control amount or the temperature of the energizing heating portion. This type of airflow meter has the advantages of good responsiveness, compactness, low cost, wide dynamic range, and high accuracy.

However, when the internal combustion engine is in steady operation under high load, the intake air amount pulsates according to the crank angle. It is known that when the intake air amount of the internal combustion engine pulsates, the intake air amount detected by this kind of hot-wire air flow meter has a value slightly deviated from the actual intake air amount.

Therefore, as described in Japanese Patent Publication No. 59-17371, an intake air amount detecting device for correcting the intake air amount detected by the hot wire air flow meter according to the fluctuation range of the output of the hot wire air flow meter is considered. Has been. According to this device, it is possible to correct the intake air amount detected by the hot-wire air flow meter according to the magnitude of the pulsation, and to make it a value that is in good agreement with the actual intake air amount.

[0005]

On the other hand, when the internal combustion engine is accelerated or decelerated, the intake air amount is in a so-called transient state in which it monotonically increases or monotonically decreases. In this transient state, it is known that the intake air amount detected by the hot-wire air flow meter is in good agreement with the actual intake air amount.

However, in the above-described intake air amount detecting device, even in such a transient state, when the intake air amount pulsates in accordance with the fluctuation range of the air flow meter output (in this case, the intake air amount increasing or decreasing amount). The same correction will be made. That is, in the above-mentioned device, the fluctuation state of the intake air amount is
Regardless of whether it is a pulsating state or a transient state, the detected intake air amount is uniformly corrected according to the fluctuation range of the air flow meter output. Therefore, the intake air amount detected by the air flow meter may deviate from the actual value due to the above correction in the transient state.

Therefore, the present invention is capable of accurately detecting the intake air amount regardless of whether the fluctuation state of the intake air amount is the pulsating state or the transient state. It was made for the purpose of providing a detection device.

[0008]

SUMMARY OF THE INVENTION The present invention, which has been made to achieve the above object, includes a hot wire type air flow meter for detecting the intake air amount of an internal combustion engine and a hot wire type air flow meter, as illustrated in FIG. And a fluctuation state detecting means for detecting a fluctuation state of the intake air amount detected by the above, and whether the fluctuation state of the intake air amount detected by the fluctuation state detecting means is a transient state or a pulsating state. And a correction for correcting the intake air amount according to the fluctuation amount of the intake air amount when the fluctuation state determination unit determines that the fluctuation state of the intake air amount is a pulsating state. Means and
An intake air amount detecting device for an internal combustion engine is provided, which is characterized in that.

[0009]

In the present invention thus constituted, the fluctuation state detecting means detects the fluctuation state of the intake air amount detected by the hot wire type air flow meter. Then, the fluctuation state determination means,
It is determined whether the fluctuation state of the intake air amount detected by the fluctuation state detection means is a pulsating state or a transient state.

This determination can be made, for example, by whether the intake air amount repeatedly increases and decreases in accordance with the rotation of the crankshaft, or whether the intake air amount only increases or decreases.
Then, the correction unit corrects the intake air amount according to the variation amount of the intake air amount when the variation state determination unit determines that the variation state of the intake air amount is the pulsating state.

As a result, when the intake air amount is in a pulsating state, the intake air amount detected by the hot wire air flow meter can be corrected to a value that closely matches the actual intake air amount. Therefore, the accurate intake air amount can be detected. Further, when the intake air amount is in a transient state, the intake air amount detected by the hot wire air flow meter is not corrected. As described above, in this transient state, the intake air amount detected by the hot-wire air flow meter is in good agreement with the actual intake air amount. Therefore, an accurate intake air amount can be detected without correction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the drawings. The present invention is not limited to these, and includes various embodiments without departing from the scope of the invention.

FIG. 2 shows a control system of a four-cylinder gasoline internal combustion engine (hereinafter simply referred to as an internal combustion engine) 11 which electronically controls a fuel injection amount and the like in accordance with an operating state. Intake air from the air filter 12 is sucked in through the intake pipe 13 and is driven by the accelerator pedal 14.
It is configured to be supplied to each cylinder of the internal combustion engine 11 via the. A heat ray type air flow meter (hereinafter simply referred to as an air flow meter) is provided inside the intake pipe 13.
Sixteen temperature sensitive elements 17 are attached. The temperature sensitive element 17 is composed of a heater such as platinum having a temperature resistance characteristic in which heat generation is controlled by an electric current and the resistance value changes depending on the temperature.

The air flow meter 16 supplies a voltage (hereinafter referred to as an air flow meter output) Vs corresponding to the intake air amount of the internal combustion engine 11 to the electronic control circuit 18. The temperature-sensitive element 17 is heated and controlled by a command from the electronic control circuit 18. The electronic control circuit 18 is CP
It is a well-known microcomputer mainly composed of U, ROM and RAM as a logical operation circuit.

In addition to the above, for the electronic control circuit 18, a detection signal from a rotation angle sensor 19 provided in a distributor 27, which will be described later, for detecting the rotation state of the internal combustion engine 11, and a cooling water temperature detection device (not shown). Detection signal,
An exhaust temperature detection signal, an air-fuel ratio detection signal, etc. are supplied as an operating state detection signal of the internal combustion engine 11. Then, based on these detection signals, the electronic control circuit 18 calculates a fuel injection amount suitable for the operating state of the internal combustion engine 11 at that time, and the injector 2 corresponding to each cylinder of the internal combustion engine 11 is calculated.
0a, 20b, 20c, 20d is supplied with a fuel injection time width signal via the registers 21a, 21b, 21c, 21d to inject the injectors 20a, 20b, 20.
The fuel injection amount is set and controlled by controlling the valve opening of c and 20d.

Injectors 20a, 20b, 20c, 2 provided for each cylinder of the internal combustion engine 11
For 0d, the fuel taken out from the fuel tank 23 by the fuel pump 22 is supplied through the distributor 24. Here, the pressure of the fuel supplied to the distributor 24 is constantly controlled by the pressure regulator 25. As a result, the fuel injection amount is accurately set and controlled by the valve opening time of the injector section.

The electronic control circuit 18 also includes an igniter 2
6, a spark plug 28 is provided to each cylinder via a distributor 27.
An ignition signal is distributed and supplied to a, 28b, 28c and 28d. In the control system of the internal combustion engine 11 configured as described above, the electronic control circuit 18 controls the air flow meter output V
The intake air amount of the internal combustion engine 11 is calculated based on s as follows.

FIG. 3 is a flow chart showing the main routine of the intake air amount detection processing executed by the electronic control circuit 18. It should be noted that this routine is a process executed every predetermined time during operation of the internal combustion engine 11, for example, every 8 msec. When the process is started, first, at step 101, the air flow meter output Vs is read. In the following step 103, an intake air amount corresponding to the read air flow meter output Vs is calculated, and this is set as a temporary air amount G0 in step 1
Move to 05.

In step 105, it is judged whether or not the load of the internal combustion engine 11 detected by another routine (not shown) is in the low load region. When the load of the internal combustion engine 11 is in the low load region, the provisional air amount G0 directly calculated from the air flow meter output Vs corresponds well to the actual intake air amount, so the routine proceeds to step 107, where the provisional air amount G0 is set. The process is terminated by setting the intake air amount G. The intake air amount G is used for various controls of the internal combustion engine 11 such as air-fuel ratio control by another routine not shown.

On the other hand, when the load of the internal combustion engine 11 is not in the low load region, the routine proceeds to step 109, where it is determined whether the change state of the air flow meter output Vs becomes a transient state and monotonically increases or decreases. to decide. It should be noted that the determination of whether or not the change state of the air flow meter output Vs is in the transient state is performed by a transient determination routine described later. If the change state of the air flow meter output Vs is in a transient state, the temporary air amount G0 corresponds well to the actual intake air amount, so the routine proceeds to step 107, and the temporary air amount G0 is treated as the intake air amount G. finish.

If a negative determination is made in step 109, that is, it is determined that the internal combustion engine 11 is not in the low load region and the change state of the air flow meter output Vs is not a transient state, the air flow meter output Vs The changing state is a pulsating state. In this case, as will be described later, the temporary air amount G0
Does not match the actual intake air amount. Then, the process proceeds to the subsequent step 111, and the temporary air amount is corrected as follows. That is, G0 (1 + CPL) is calculated using the correction amount CPL calculated in the correction amount calculation routine described later. In step 111, this is set as the intake air amount G, and the processing ends.

Next, the transient discrimination routine used in step 105 will be described. FIG. 4 is a flowchart showing the transient discrimination routine. It should be noted that this routine is executed every predetermined time (for example, about 1 msec. Is desirable in the case of an engine speed of 1000 rpm) which is sufficiently smaller than the rotation cycle of the internal combustion engine 11.

First, each variable Vma used in this routine is
x, Vmin and each counter Cmax, Cmin are 180
Each CA is reset as follows. That is,
Vmax =-. Infin., Vmin = +. Infin., Cmax = 0, Cmin = 0
It is said that. When the process is started, first, in step 201, the air flow meter output Vs is read, and then in step 2
At 03, it is judged whether the air flow meter output Vs is larger than the variable Vmax. If an affirmative decision is made in step 203, the routine proceeds to step 205, where the air flow meter output V
Substitute the value of s for the variable Vmax. That is, the variable Vmax is a variable for storing the maximum value of the air flow meter output Vs.

In the following step 207, the counter Cmax
Is further incremented, and in the subsequent step 209, it is determined whether or not the counter Cmax has become equal to or greater than the threshold value Cs read from the table (not shown) based on the engine speed Ne of the internal combustion engine 11. If the counter Cmax is less than the threshold value Cs, the process is terminated as it is. On the other hand, when the counter Cmax becomes equal to or greater than the threshold value Cs, the process proceeds to step 211, and it is determined that the change state of the air flow meter output Vs is the transient state, and the process is ended. Here, the threshold value Cs is set to a value that is less than the number of times this routine is executed during 180 ° CA, and that is at least half the value, as described later.

If a negative determination is made in step 203, the flow proceeds to step 213 and the air flow meter output Vs
Is smaller than the variable Vmin. Step two
When a positive determination is made in step 13, the variable Vmin storing the minimum value of the air flow meter output Vs is updated with the current air flow meter output Vs in step 215, and the counter Cmin is incremented in step 217. Further, in steps 219 and 221, the counter Cmin is equal to the threshold value Cs.
When it becomes the above, it is determined that the change state of the air flow meter output Vs is the transient state. On the other hand, if a negative decision is made in step 213, the processing is ended as it is.

FIG. 5 is a time chart showing changes in various variables in the transient discrimination routine. FIG. 5A shows a case where the change state of the air flow meter output Vs is the pulsating state. In this case, the air flow meter output Vs is
The increase and decrease are repeated in a substantially sinusoidal manner with a cycle of 180 ° CA.

As shown in the figure, the air flow meter output Vs
While V is increasing (time points A to B), the variable Vmax is updated every time this routine is executed. Along with this, the counter C
max also increases each time this routine is executed. Next, when the air flow meter output starts to decrease (time B), the variable Vmax is not updated and the counter Cmax also does not change. Also,
The variable Vmin does not change until the air flow meter output Vs decreases below the initial value.

When the air flow meter output Vs decreases below the initial value (time point C), the variable Vmin is updated every time this routine is executed, and the counter Cmin increases accordingly.
Subsequently, the air flow meter output Vs starts to increase again (time point D), but the variable V max is the maximum value of the air flow meter output Vs and is not newly updated. Therefore, the counter Cmax also does not change.

As described above, when the change state of the air flow meter output Vs is the pulsating state, since the increase / decrease is repeated, both the counters Cmax and Cmin are less than half the number of times of execution of this routine. Therefore, the counters Cmax and Cmi
None of the n exceeds the threshold value Cs.

On the other hand, FIG. 5B shows the air flow meter output V
It represents changes in various variables when the change state of s is a transient state. Although the figure illustrates the case where the air flow meter output Vs monotonically increases, the case where the air flow meter output Vs monotonously decreases can be considered in the same manner. As shown in the figure, the air flow meter output Vs continues to increase in all sections (F to H). Therefore, the counter Cmax is incremented every time this routine is executed in the entire section (F to H). Then, the counter Cmax exceeds the threshold value Cs at the time when this routine is executed a predetermined number of times (time G). Then, the transient state is determined at this time.

FIG. 6 shows the air flow meter output V in the pulsating state.
It is explanatory drawing showing the change of temporary air amount G0 calculated directly from s. As shown in the figure, the temporary air amount G0 is the maximum value Gmax.
And pulsates in a sinusoidal manner between the minimum value Gmin. The temporary air amount G0 in such a pulsating state is slightly deviated from the actual intake air amount of the internal combustion engine 11. FIG. 7 shows the ratio of the actual air-fuel ratio to the lean side with respect to the target air-fuel ratio (hereinafter referred to as lean ratio) when the pulsating temporary air amount G0 is used as it is for the air-fuel ratio control of the internal combustion engine 11. FIG. Here, the pulsation rate PL is a parameter defined by a predetermined function PL = f (Gmax, Gmin) ... A, and represents that the larger the pulsation rate PL, the more the pulsation of the provisional air amount G0. There is. As shown in the figure, it can be seen that the lean rate increases as the pulsation rate PL increases. This means that the larger the pulsation rate PL, the smaller the temporary air amount G0 becomes with respect to the actual intake air amount. Further, it can be seen that even if the pulsation rate PL is the same, the lean rate differs depending on the engine speed Ne of the internal combustion engine 11.

Therefore, in this embodiment, as described above,
When the change state of the air flow meter output Vs is the pulsating state, the temporary air amount G0 is corrected in step 111.
Next, the calculation process of the correction amount CPL used in step 111 will be described. FIG. 8 is a flowchart showing a correction amount calculation routine for calculating the correction amount CPL. It should be noted that this process is a process executed every time the internal combustion engine 11 rotates 180 ° CA.

When the processing is started, first, step 301
At step 303, the maximum value Gmax of the temporary air amount G0 is calculated, and at step 303, the minimum value Gmin of the temporary air amount G0 is calculated.
In the following step 305, the calculated maximum value Gmax and minimum value Gmin are substituted into the expression A, and the pulsation rate PL of the temporary air amount G0 is set.
Is calculated. In the following step 307, the rotation angle sensor 1
Based on the signal from 9, the engine speed Ne of the internal combustion engine 11 is read. Subsequently, when the process proceeds to step 309, based on the map shown in FIG. 9, the pulsation rate PL and the engine speed N
The correction amount CPL corresponding to e is read.

The map of FIG. 9 is obtained by replacing the lean rate in FIG. 7 with the correction amount CPL as it is.
That is, the lean ratio represents how much the actual intake air amount becomes larger than the temporary air amount G0. Therefore, if the temporary air amount G0 is increased and corrected by the correction amount CPL having the same value as the lean ratio. The actual intake air amount will be obtained.

As described above, in the present embodiment, when the tentative air amount G0 obtained from the air flow meter output Vs does not match the actual intake air amount, the temporary air amount G0 is corrected to obtain an actual intake air amount. It can be a matching value. Further, the above correction is not performed during the transition in which the temporary air amount G0 is in good agreement with the actual intake air amount. Therefore, in this embodiment, it is possible to detect the accurate intake air amount G in any case, whether the fluctuation state of the temporary air amount G0 is the pulsating state or the transient state.

Further, when the internal combustion engine 11 is in the low load region, the provisional air amount G0 directly calculated from the air flow meter output Vs corresponds well to the actual intake air amount. Therefore, in the above embodiment, no correction is made even in this low load region. In the low load region, the pulsation rate PL becomes smaller and the corresponding correction amount CPL also becomes smaller. However, by not performing the correction from the beginning, the load on the electronic control circuit 18 can be lightened.

In the above embodiment, steps 201, 203, 205, 213 and 215 of the transient discrimination routine serve as the fluctuation state detecting means and steps 207 to 21.
1 and 217 to 221 correspond to the fluctuation state determination means, and step 111 of the main routine and the correction amount calculation routine correspond to the correction means.

On the other hand, in the above embodiment, the threshold value Cs is read from the table (not shown) based on the engine speed Ne, but the threshold value Cs is set to a constant value and the internal combustion engine 11 rotates the transient determination routine by a predetermined amount. Every time (eg 5 ° CA
It may be executed every time the motor rotates. Further, in the above embodiment, the maximum value Gmax and the minimum value Gmin of the temporary air amount G0 are set.
Is calculated and the pulsation rate PL is calculated based on this, the variables Vmax and Vmin calculated in the transient determination routine may be used instead of the maximum value Gmax and the minimum value Gmin.
Similar actions and effects can be obtained in these cases as well.

In addition to the above, various modes can be considered for the transient discrimination routine and the correction amount calculation routine described in the above embodiment. FIG. 10 is a flowchart showing another embodiment of the transient discrimination routine. When the process is started, first, at step 401, the air flow meter output Vs is read. In the following step 403, the amount of change ΔVs (i) between the airflow meter output Vs (i) read this time and the airflow meter output V (i−1) read last time is calculated by the following equation.

ΔVs (i) = Vs (i) −Vs (i−1) In the following step 405, it is determined whether the internal combustion engine 11 has rotated 180 ° CA after starting the process. Still 1
If it is not rotated by 80 ° CA, step 40 again.
Repeat 1,403. Internal combustion engine 1 by this loop
Change of air flow meter output Vs ΔVs (i) (i = 1, 2, 3, ...) While 1 rotates 180 ° CA
Are sequentially calculated.

When the internal combustion engine 11 rotates 180 ° CA and proceeds to step 407, the variation ΔVs (i) (i =
1, 2, 3, ...) Sum ΣΔVs (i) is calculated.
In the following step 409, the calculated sum ΣΔVs (i)
Is larger than a preset constant A or not.
If the sum ΣΔVs (i) is larger than A, step 41
In step 1, it is judged to be in a transient state and the process is terminated. If it is A or less, the process proceeds to the following step 413. Step 413
Then, it is determined whether the sum ΣΔVs (i) is smaller than −A. If the total sum ΣΔVs (i) is smaller than −A, it is determined in step 411 that it is in the transient state, the processing is terminated, and −A
If the above is the case, the process is terminated.

Here, the constant A is set to a value sufficiently close to zero. That is, when the air flow meter output Vs is in a pulsating state, the air flow meter output Vs repeatedly changes in a cycle of 180 ° CA, and therefore the increase amount and the decrease amount of the air flow meter output Vs should be the same during 180 ° CA. Is. Therefore, the sum ΣΔVs (i) has a value substantially equal to 0. Therefore, in this embodiment, the sum ΣΔVs (i)
Is in the range of −A ≦ ΣΔVs (i) ≦ A and whether the pulsating state or the transient state is determined. When calculating the variation ΔVs (i) in this way, the pulsation rate PL can be defined based on the maximum value of | ΔVs (i) |.

[0043]

As described in detail above, in the intake air amount detecting device for an internal combustion engine of the present invention, the hot air type air flow meter detects when the detected value of the hot wire type air flow meter deviates from the actual value of the intake air amount. The intake air amount thus obtained can be corrected to a value that closely matches the actual intake air amount.
Further, the above correction is not performed at the time of a transition in which the detected value of the hot wire type air flow meter is in good agreement with the actual value of the intake air amount.

Therefore, according to the present invention, it is possible to accurately detect the intake air amount regardless of whether the fluctuation state of the intake air amount is the pulsating state or the transient state.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of the present invention.

FIG. 2 is a schematic system diagram of a system configuration using an embodiment.

FIG. 3 is a flowchart showing a main routine of an intake air amount detection process of the embodiment.

FIG. 4 is a flowchart showing a transient state determination routine of the embodiment.

FIG. 5 is a time chart showing changes in various variables in the transient determination routine.

FIG. 6 is an explanatory diagram showing a change in a provisional air amount in a pulsating state.

FIG. 7 is an explanatory diagram showing a lean ratio when the temporary air amount is used as it is for air-fuel ratio control.

FIG. 8 is a flowchart showing a correction amount calculation routine of the embodiment.

FIG. 9 is an explanatory diagram showing a relationship between a pulsation rate, an engine speed, and a correction amount.

FIG. 10 is a flowchart showing another embodiment of the transient state determination routine.

[Explanation of symbols]

11 ... Internal Combustion Engine 13 ... Intake Pipe 16 ... Heat Wire Type Air Flow Meter 17 ... Temperature Sensing Element 18 ... Electronic Control Circuit 19 ... Rotation Angle Sensor

Claims (1)

[Claims] 1. A hot wire type air flow meter for detecting an intake air amount of an internal combustion engine, a fluctuation state detecting means for detecting a fluctuation state of the intake air amount detected by the hot wire type air flow meter, and a fluctuation state detecting means. And a fluctuation state determining means for determining whether the fluctuation state of the intake air amount detected in step 1 is a transient state or a pulsating state, and the fluctuation state determining means determines the fluctuation state of the intake air amount in a pulsating state. The intake air amount detection device for an internal combustion engine, comprising: a correction unit that corrects the intake air amount according to the variation amount of the intake air amount.