JPH05288113A - Sucked air flow detection apparatus for internal combustion engine - Google Patents

Abstract

PURPOSE:To enhance the correction precision by correcting a detection error generated immediately after closure of a power source into a temperature- sensitive flow meter. CONSTITUTION:Measurement is made on a time duration tD starting from a time when a power supply to a temperature-sensitive flow meter 1 is interrupted (S1 to S6). In measuring a time duration (t) starting from the closure of a power into the temperature-sensitive flow meter, an initial value of the time duration (t) is set by being varied depending upon the measured time duration tD (S9). When the above time duration tD is short it is estimated that the temperature of a temperature-sensitive resistor RH is relatively high. By setting a relatively large value as the above initial value, therefore, a time length larger than an actual time length is so arranged as to be deemed as having lapsed from closure of the power source. A correction coefficient (K) is set in corresponding relation to the time duration (t) starting from the closure of the power source (S13), by which a data (S12) of a sucked air flow Q as converted from an output voltage Us of the temperature-sensitive flow meter 1 is corrected S14 by use of the correction coefficient (K).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air flow rate detecting device for an internal combustion engine, and more particularly to a temperature sensitive flow meter for detecting an engine intake air flow rate based on a temperature sensitive resistance arranged in an intake passage of the internal combustion engine. The present invention relates to a technique for compensating for a detection error at the initial stage of power-on.

[0002]

2. Description of the Related Art An electronically controlled fuel injection system for an internal combustion engine is equipped with an air flow meter (air flow meter) for detecting the intake air flow rate Q of the engine, and the intake air flow rate Q detected by this air flow meter is It is known that the basic fuel injection amount Tp = K × Q / N (K is a constant) is calculated from the engine rotation speed N.
There is one in which a temperature-sensitive flow meter as disclosed in Japanese Utility Model Laid-Open No. 59-78926 is used.

In the temperature-sensitive flow meter, a so-called hot wire type or hot film type temperature sensitive resistor is arranged in the intake passage, and a current is supplied to the temperature sensitive resistor to generate heat at a constant temperature (resistance value). Then, the temperature decrease due to the intake air is compensated for by increasing the supply current, and the intake air flow rate is obtained from the current value. That is, when the temperature-sensitive flow meter 1 in FIG. 4 is taken as an example, in addition to the temperature-sensitive resistance R _H (hot wire or hot film), temperature compensation resistance R _K, reference resistance R _s, fixed resistance R _{1 ,} R ₂ and the bridge circuit B is constituted by them.

The temperature sensitive resistor R of the bridge circuit B
_H and the reference resistance R _s are connected in series, the potential at the voltage dividing point (the terminal voltage of the reference resistance R _s ) and the temperature compensation resistance R
_K and the potential of the voltage dividing point (the terminal voltage of the fixed resistor R ₂ ) on the side where the fixed resistors R _{1 and} R ₂ are connected in series are input to the differential amplifier OP, and the difference The supply current to the bridge circuit B is corrected via the transistor Tr according to the output of the dynamic amplifier OP.

That is, when the intake air flow rate of the engine increases, for example, when the bridge circuit B is in equilibrium,
The temperature-sensitive resistance R _H is further cooled by this air flow, its resistance value decreases, and the terminal voltage of the reference resistance R _s increases,
The bridge circuit B becomes unbalanced and the output of the differential amplifier OP increases. As a result, the supply current to the bridge circuit B controlled by the transistor Tr increases, the temperature-sensitive resistor R _H is heated, and its resistance value increases, whereby the balanced condition of the bridge circuit B is restored.

Here, when the temperature of the intake air decreases, for example, the temperature-sensitive resistor R _H is cooled and its resistance value decreases, but the temperature-compensating resistor R _{K in the} same atmosphere as the temperature-sensitive resistor R _H.
At the same time, the resistance value of the bridge circuit B is decreased and the resistance value of the bridge circuit B is decreased. Therefore, the change of the current value supplied to the bridge circuit B due to the temperature change of the intake air is suppressed. Therefore, the intake air flow rate of the engine and the current supplied to the bridge circuit B correspond independently of the intake air temperature, and the intake air flow rate can be measured by detecting the terminal voltage of the reference resistance R _s. it can.

[0007]

By the way, in the above-mentioned temperature sensitive flow meter using the temperature sensitive resistor, as described above, the supply current is controlled so as to keep the temperature of the temperature sensitive resistor constant. The temperature-sensitive flowmeter has a temperature-sensitive flowmeter that is supplied with power until the temperature-controlled resistance in the ambient temperature state (normal temperature state) reaches the normal control temperature (for example, about 400 ° C). It will require a predetermined time according to the heat capacity of the resistance, and in particular, in a hot film type temperature sensitive flow meter with a large heat capacity in general compared to the hot wire type,
It usually takes a relatively long time to reach the control temperature.

[0008] Here, the bridge circuit is in an unbalanced state and a high current is supplied to raise the temperature of the temperature-sensitive resistor from the time when the temperature of the temperature-sensitive resistor is turned on until it reaches the vicinity of the normal control temperature. The high current at this time does not depend on the temperature drop of the temperature sensing resistor due to the increase of the intake air flow rate, but raises the temperature of the temperature sensing resistor from the ambient temperature state to around the normal control temperature. Since it is required for this, the intake air flow rate cannot actually be detected with high accuracy between the time the power is turned on and the temperature near the normal control temperature. Will be detected (see FIG. 8).

Therefore, if the starting state is entered before the temperature-sensitive resistance reaches the vicinity of the normal control temperature, the basic fuel injection amount is calculated based on the air flow rate larger than the true intake air flow rate. There was a fear that the air-fuel ratio of the engine intake air-fuel mixture would be made rich and the starting characteristics and exhaust characteristics would be adversely affected. Furthermore, as shown in FIG. 8, since the error characteristic changes with the elapsed time from the power-on, there is a problem that the influence on the startability changes depending on the time from the power-on to the start of the start. ..

FIG. 8 shows the result of an experiment in which the temperature-sensitive resistor is arranged in an air flow of a constant flow rate and the detection error decreases as the temperature of the temperature-sensitive resistor rises after the power is turned on. In other words, it shows a static error characteristic according to the elapsed time. As a technique capable of solving such a problem, the applicant of the present invention calculates the amount of detection error until the temperature of the temperature sensitive resistor reaches the vicinity of the normal control temperature after the power source voltage is applied to the temperature sensitive flow meter. It was previously proposed that the characteristic of converting the output voltage of the temperature-sensitive flow meter into the data of the intake air flow rate is corrected based on the elapsed time by performing a simulation based on the elapsed time (Japanese Patent Application No. 3-31452). reference).

However, even if the power supply to the temperature-sensitive flow meter is cut off, the temperature of the temperature-sensitive resistor does not instantly return to room temperature, but gradually returns to room temperature over a certain period of time. If the temperature-sensitive flowmeter is turned on again before it returns to room temperature, the correction based on the elapsed time is overcorrected because the characteristics are matched when the power is turned on at normal temperature. There was a case (see FIG. 9).

The present invention has been made in view of the above problems, and the correction of the detection error from the power-on of the temperature-sensitive flow meter until the temperature-sensitive resistance reaches the vicinity of the normal control temperature, from the power-on. It is an object of the present invention to make it possible to perform highly accurate correction even when the power supply is repeatedly turned on and off when the operation is performed based on the elapsed time.

[0013]

Therefore, an intake air flow rate detecting device for an internal combustion engine according to the present invention is constructed as shown in FIGS. In FIG. 1, a temperature-sensitive flow meter outputs a detection signal corresponding to an engine intake air flow rate based on a resistance value change of a temperature-sensitive resistance arranged in an intake passage of an internal combustion engine according to the intake air flow rate.

The on-time measuring means measures the elapsed time after the power supply to the temperature-sensitive flow meter is turned on, and the off-time measuring means measures the elapsed time after the power supply to the temperature-sensitive flow meter is cut off. To do. Further, the conversion means converts the detection signal from the temperature-sensitive flow meter into a value corresponding to the intake air flow rate.

Here, the on / off time correction means corrects the conversion characteristics of the conversion means based on the elapsed times measured by the on time measurement means and the off time measurement means, respectively. On the other hand, in FIG. 2, in place of the off-time measuring means and the on-off time correcting means shown in FIG. 1, a power-on level detecting means and a on-time and power-on level correcting means are provided. I am configuring.

Here, the power-on level detecting means samples the detection signal output immediately after power-on of the temperature-sensitive flow meter. The on-time and power-on level correcting means corrects the conversion characteristic of the converting means based on the elapsed time measured by the on-time measuring means and the detection signal sampled by the power-on level detecting means. ..

Further, in FIG. 3, an erroneous detection time measuring means and an on time and erroneous detection time correcting means are provided in place of the off time measuring means and the on / off time correcting means shown in FIG. Are configured. Here, the erroneous detection time measuring means measures the time during which the detection signal of the temperature-sensitive flow meter has a value indicating an intake air flow rate equal to or higher than a predetermined value at the initial stage of power-on of the temperature-sensitive flow meter. Then, the correction means based on the on-time and the erroneous detection time corrects the conversion characteristic of the conversion means based on the elapsed time measured by the on-time measuring means and the time measured by the erroneous detection time measuring means.

[0018]

[Function] The temperature state of the temperature-sensitive resistor of the temperature-sensitive flow meter when the power is turned on can be estimated by the elapsed time after the power supply is cut off. Therefore, by measuring the elapsed time, the power is turned on. The accuracy of the correction based on the elapsed time since the power is turned on can be improved in response to the variation in the temperature state of the temperature-sensitive resistance.

Further, the lower the temperature of the temperature-sensitive resistor, the larger the level of the detection signal immediately after power-on is with respect to the level of the regular detection signal. Therefore, instead of measuring the off time, power-on is performed. By sampling the detection signal immediately after that, the temperature state of the temperature-sensitive resistor when the power is turned on can be estimated. Furthermore, if the temperature of the temperature-sensitive resistor when the power is turned on is low, a detection signal having a large detection error is output for that long time, so that it takes a long time (the detection signal has a value indicating an intake air flow rate above a predetermined value). The temperature state of the temperature sensitive resistor when the power is turned on can also be estimated by measuring (time).

[0020]

EXAMPLES Examples of the present invention will be described below. FIG. 4 shows a hardware configuration of the embodiment, which is a temperature sensitive flow meter (AF /
Power supply voltage (battery voltage) V _B is applied to M) 1 via relay 7. Then, the output voltage Us (detection signal) of the temperature-sensitive flow meter 1 is input via the A / D converter 3 to the control unit 4 incorporating a microcomputer.

In addition, various sensors for detecting engine operating conditions such as a rotation sensor 5 for detecting the engine speed N are provided, and together with the output voltage Us of the temperature-sensitive flow meter 1,
Detection signals from these sensors are also input to the control unit 4. The control unit 4 is connected to a power source (battery) via the key switch 2 and controls the power supply to the temperature-sensitive flow meter 1 by controlling the on / off of the relay 7. Is becoming

Here, the control unit 4 calculates the basic fuel injection amount Tp = K × Q / N (K is a constant) based on the detected values of the engine intake air flow rate Q and the engine rotation speed N, and at the same time, The final fuel injection amount Ti is calculated by appropriately correcting the basic fuel injection amount Tp according to operating conditions such as engine temperature, and an injection pulse signal having a pulse width corresponding to this fuel injection amount Ti is synchronized with the engine rotation. The fuel supply to the engine is electronically controlled by outputting to the electromagnetic fuel injection valve 6 at the predetermined timing.

Since the structure and operation of the temperature-sensitive flow meter 1 have been described above, a detailed description of the temperature-sensitive flow meter 1 will be omitted here. Next, the control unit 4
The first embodiment of the intake air flow rate Q detection performed by
A description will be given according to the flowchart of FIG. It is assumed that the control unit 4 has software functions of the on-time measuring means, the off-time measuring means, the on / off time correcting means, and the converting means, as shown in the flowchart of FIG.

The flow chart of FIG. 5 shows the intake air flow rate Q.
Is executed every predetermined sampling time (for example, 4 ms), and the basic fuel injection amount Tp is calculated using the final detected value obtained here. First, in step 1 (denoted as S1 in the figure, the same applies hereinafter),
Determine whether the key switch 2 is on or off.

If the key switch 2 is off,
Proceeding to step 2, the power supply to the temperature sensitive flow meter 1 is cut off. Here, even if the key switch 2 is turned off, the control unit 4 maintains its own power supply, and proceeds to step 3 to elapse time (off time) after the power supply to the temperature-sensitive flow meter 1 is cut off. Measure T _D.

Next, the time T _D is compared with a preset predetermined time T _DMAX . The predetermined time T _DMAX is
The temperature of the temperature sensitive resistor R _H near the normal control temperature is set as the time required for the temperature to drop to near room temperature after the power supply is cut off. When the measured time T _D is less than or equal to the predetermined time T _DMAX , the process returns to step 1 again, and when the key switch 2 is continuously off, the time T _D is continuously measured. Then, long time until the key switch 2 is again turned on after being turned off, when the time T _D is exceeding the predetermined time T _DMAX, was set to a predetermined time T _DMAX to the time T _D in Step 5 After that, the process proceeds to step 6 and the power supply to the control unit 4 is cut off by itself.

That is, the power supply to the temperature sensitive flow meter 1 is cut off.
Then, the elapsed time T from that point _DIs measured
Measuring time T_DIs the temperature-sensitive resistance from the interruption of the power supply.
R_HOff to estimate the temperature drop of
Later elapsed time T_DIs the predetermined time T_DMAXTemperature above room temperature
If it is estimated that the
Is useless, so stop the time measurement at that point, and
Enough off time to cool down to
Memorize

Even if the power is cut off in step 6, the data of the elapsed time T _D is retained.
Data of the elapsed time T _D (= T _DMAX ) is stored in the backup memory. On the other hand, when it is determined in step 1 that the key switch 2 is on, the process proceeds to step 7 and the temperature-sensitive flow meter 1 is powered on.

Then, it is judged in step 8 whether or not the power is turned on for the first time.
Then, the initial value tφ of the elapsed time t data from the power-on is set from the data of the elapsed time T _D measured in the immediately previous power-off state. Here, the temperature sensitive flow meter 1
If the re-power in a short time from the power supply is cut off is turned to the (T _D <T _DMAX), the temperature-sensitive resistor R _H
It can be considered that the power supply is turned on again before the temperature of the temperature drops to room temperature, and conversely, when the power supply is turned on after the time T _D exceeding T _DMAX , the temperature-sensitive resistor R _H It can be considered that the power is turned on at a temperature of room temperature.

In the present embodiment, as will be described later, the amount of detection error during power-on of the temperature-sensitive flow meter 1 from when the power is turned on to when the temperature of the temperature-sensitive resistor R _H rises up to around the normal control temperature. Temperature-sensitive resistance R based on the elapsed time (ON time) t
The temperature rise of _H is estimated and corrected. However, the estimation of the temperature based on the elapsed time t corresponds to the temperature-sensitive resistor R _{H in} the normal temperature state when the power is turned on. However, an error will occur in the correction.

Here, the fact that the temperature is higher than room temperature can be regarded as the fact that the power is turned on before the time when the power is actually turned on by the temperature difference. Therefore, when the off time T _D is T _DMAX ,
Since the power is turned on at room temperature, the on time t
Given 0 as an initial value tφ the off time T _D is T _{DM AX}
The shorter the temperature is, the larger the initial value tφ is given when the temperature of the temperature-sensitive resistor R _H when the power is turned on is higher than the normal temperature.

That is, when the off-time T _D is extremely short and the temperature of the temperature-sensitive resistor R _H is estimated to be near the normal control temperature, the temperature-sensitive resistor at room temperature is set as the initial value of the on-time t. By making the initial value tφ a time close to the time from when the power is supplied to R _H until it reaches the vicinity of the normal control temperature, the correction based on the on-time t is substantially not performed.

In the measurement of the on-time t in step 10, the time is measured from the initial value tφ given when the power is turned on as described above. In step 11, the output voltage Us (detection signal) from the temperature-sensitive flow meter 1 is read, and in the next step 12, the output voltage Us is converted into the data of the intake air flow rate Q by using a preset conversion table. Convert to.

Further, in step 13, the map in which the correction coefficient K is set in advance according to the elapsed time t after the power is turned on is referred to, and the correction coefficient K corresponding to the elapsed time t at the present time is referred to.
Search for and ask. And in step 14, step
In step 12, the data of the intake air flow rate Q obtained by converting the output voltage Us is multiplied by the correction coefficient K for correction, and the correction result is set as the final detected intake air flow rate Q.

In the case of the present embodiment, the correction coefficient K is set as follows when the temperature of the temperature sensitive resistor R _H is lower than the normal control temperature.
Since a voltage higher than the voltage corresponding to the actual intake air flow rate Q is output, the correction coefficient is 1.0 or less as the elapsed time t after power-on is short and the temperature of the temperature-sensitive resistor R _H is estimated to be low. Is set to a small value. As a result, it is possible to correct the occurrence of a large detection error while the temperature-sensitive resistance R _H reaches the vicinity of the normal control temperature.

However, according to the above embodiment, the power supply to the temperature sensitive flow meter 1 is turned off again within a short time after the power supply to the temperature sensitive flow meter 1 is cut off, and the temperature of the temperature sensitive resistor R _H is higher than the room temperature. Even if the power is turned on in this state, the temperature decrease at the time of power supply cutoff is estimated based on the time T _D after the power supply cutoff, and the elapsed time t from the power supply turn on based on this estimation.
Correct the correction control based on. Therefore, even if the power is turned on again within a short time after the power supply is cut off, highly accurate correction can be performed.

In the above embodiment, the measurement of the elapsed time t after the power is turned on is corrected based on the elapsed time T _D after the power supply is cut off. However, the off time T _D and the on time t are The correction may be performed by setting a correction coefficient as a parameter and multiplying it by the data of the intake air flow rate Q. Further, the output voltage Us may be corrected based on the off time T _D and the on time t and then converted into the intake air flow rate Q, and the correction procedure is not limited to the above. ..

However, when the temperature drop is estimated by the elapsed time T _D after the power supply is cut off as described above, the temperature-sensitive resistor R _H when the power supply is cut off has reached the normal control temperature. Is assumed. Therefore, when the power is on for a short time, the accuracy of the temperature drop estimation based on the elapsed time T _D deteriorates. Therefore, when the power is cut off before the temperature-sensitive resistor R _H reaches the normal control temperature, the data (on elapsed time t)
May be stored, and the initial value setting of the ON time t measurement based on the OFF elapsed time T _D described above may be corrected with the previous ON time.

By the way, the occurrence of the detection error of the temperature sensitive flow meter 1 when the power is turned on is caused by the temperature of the temperature sensitive resistor R _H being lower than the normal control temperature as described above. In some cases, the lower the temperature (the closer to room temperature)
The output voltage Us of the temperature-sensitive flow meter 1 becomes high. Therefore, the output voltage Usφ at the first time of power-on becomes higher as the temperature of the temperature-sensitive resistor R _{H at} the time of power-on is lower, and the output voltage Usφ is measured instead of measuring the off time T _D. The temperature state of the temperature-sensitive resistor R _{H at} the time of turning on the power can also be estimated by sampling.

Output voltage Usφ at power-on
A second embodiment in which the correction control is performed based on the sampling of 1 will be described with reference to the flowchart of FIG. still,
As shown in the flow chart of FIG. 6, the control unit 4 is software-provided with functions as an on-time measuring means, a power-on level detecting means, a on-time and power-on level correcting means, and a converting means. And

In the flow chart of FIG. 6, first, in step 21, the on / off state of the key switch is discriminated, and according to the on / off discrimination, in step 22 or step 29, the power supply to the temperature-sensitive flow meter 1 is turned on and off. Take control. When the power is being supplied, the process proceeds to step 23, where it is determined whether or not the power is being turned on for the first time. When the power is turned on for the first time, the process is advanced to step 24 and the output of the temperature-sensitive flow meter 1 at that time is determined. Read the voltage Usφ.

Then, in the next step 25, based on the read output voltage Usφ at the first power-on,
Similar to the above embodiment, the initial value tφ is set in the measurement of the elapsed time t after the power is turned on. Here, as described above, it is estimated that the higher the output voltage Usφ, the closer the temperature of the temperature-sensitive resistor R _H when the power is turned on to room temperature, and conversely,
When the output voltage Usφ is low, it is estimated that the temperature of the temperature sensitive resistor R _H is higher than room temperature because the power is turned on again within a short time after the power supply is cut off.

Therefore, when the output voltage Usφ is low, the initial value tφ is set to a large value, and apparently the power is supplied to the temperature-sensitive flow meter 1 from a point before the actual power is supplied, The temperature sensing resistance R _H is corrected to some extent by the relatively long on-time. In step 26, the elapsed time t after the power is turned on is sequentially counted up based on the initial value setting.

In step 27, the output voltage Us of the temperature sensitive flow meter 1 is read, and in step 28, a correction coefficient is obtained by converting the output voltage Us based on the elapsed time t. The intake air flow rate Q data is multiplied and the correction result is output as the final detection data of the intake air flow rate Q. According to the above-described embodiment, similarly to the embodiment shown in the flow chart of FIG. 5, it is possible to enhance the correction accuracy when the power is turned on within a short time after the power supply is cut off, and In the embodiment, the temperature-sensitive resistance R _{H at} that time is changed from the output voltage Usφ at the first power-on.
Even if there is a situation in which the power supply is repeatedly turned on and off frequently before that, the temperature sensing at power-on is performed with high accuracy without being affected by the past on / off state. The temperature state of the resistance R _H can be estimated.

Further, when the power is turned on while the temperature of the temperature sensitive resistor R _H is relatively high, the output should converge to the normal output level faster, so the abnormal output state (output The temperature-sensitive resistance R when the power is turned on is maintained even after the duration of the voltage Us is higher than a predetermined value).
The temperature state of _H can be estimated. A third embodiment using such characteristics will be described with reference to the flowchart of FIG.

As shown in the flow chart of FIG. 7, the control unit 4 is provided with software as functions of the on-time measuring means, the erroneous detection time measuring means, the correcting means by the on-time and the erroneous detection time, and the converting means. It is assumed that In the flowchart of FIG. 7, first,
Power on / off of the temperature-sensitive flow meter 1 is controlled according to ON / OFF of the key switch 2 (steps 31, 32,
41).

Then, in the state where the power is supplied to the temperature-sensitive flow meter 1, it is determined in step 33 whether or not the power is initially turned on (for example, within 2 seconds after the power is turned on). If so, the routine proceeds to step 34, where the output voltage Us of the temperature sensitive flow meter 1 is read. Then step 35
In, the read output voltage Us is compared with a voltage of a preset threshold level. Here, when the output voltage Us at the initial stage of power-on exceeds the threshold level (when the detected intake air flow rate Q is a predetermined value or more), the process proceeds to step 36, and the duration of such a state is measured. Time t _D for counting up, and when the output voltage Us is equal to or lower than the threshold level, the process proceeds to step 37 without counting up time t _D.

The threshold level is a value that is not generally output in the initial state of power-on (the intake air flow rate Q is 0) when the temperature-sensitive resistor R _H has reached the vicinity of the normal control temperature. Output voltage U
When s exceeds the threshold level for a long time (erroneous detection time) in the initial stage of power-on, it is estimated that the temperature of the temperature-sensitive resistor R _H is lower than the normal control temperature.

Therefore, in the next step 37, the initial value tφ of the elapsed time t after the power is turned on is the same as in the previously described embodiment.
As an initial time tφ set according to the time t _D
To set. That is, when the measured time t _D is short, it is estimated that the temperature of the temperature-sensitive resistor R _H when the power is turned on is close to the normal control temperature, so that the initial time tφ is the normal temperature. A time close to the time from when the temperature resistance R _H is turned on to when it reaches the normal control temperature is set as the initial value tφ so that the correction based on the on-time t is not substantially performed. On the other hand, when the time t _D is long, the temperature-sensitive resistance R _H when the power is turned on is that much.
Is estimated to be close to room temperature, the initial time t
With φ close to 0, general temperature sensing resistance R
_Make the correction in the same way as when _H is powered on.

When the initial value of the time t for measuring the elapsed time after the power is turned on is set as described above, the step
At 38, the time t is measured based on the initial value. In step 39, the output voltage U from the temperature sensitive flow meter 1
Read s. Then, in step 40, the output voltage Us is changed by the correction coefficient set based on the ON time t.
Correct the data of the intake air flow rate Q obtained by converting from
This correction result is set as the final detection data.

[0051]

As described above, according to the present invention, when the detected value is corrected according to the elapsed time after the power supply to the temperature-sensitive flow meter is turned on, the temperature of the temperature-sensitive resistor is lowered to room temperature. Even when the power is turned on without power, the temperature state of the temperature-sensitive resistor at power-on can be estimated and correction can be added to the correction control based on the elapsed time (ON time). Even if the power is turned on again within a short time after the interruption, it is possible to perform the correction with high accuracy.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing the basic configuration of the present invention.

FIG. 3 is a block diagram showing the basic configuration of the present invention.

FIG. 4 is a system diagram showing a hardware configuration of an embodiment.

FIG. 5 is a flowchart showing a first embodiment of correction of a detected value of an intake air flow rate.

FIG. 6 is a flowchart showing a second embodiment of correction of a detected value of an intake air flow rate.

FIG. 7 is a flowchart showing a third embodiment of correction of a detected value of an intake air flow rate.

FIG. 8 is a diagram showing static error characteristics when the power of the temperature-sensitive flow meter is turned on.

FIG. 9 is a time chart showing the characteristics of temperature change when the power is turned on and off for the temperature sensitive flow meter.

[Explanation of symbols]

1 Temperature-sensitive flow meter 2 Key switch 3 A / D converter 4 Control unit 7 Relay _RH Temperature-sensitive resistor B Bridge circuit

Claims (3)

[Claims] 1. A temperature-sensitive flow meter for outputting a detection signal corresponding to an engine intake air flow rate based on a resistance value change of a temperature-sensitive resistance arranged in an intake passage of an internal combustion engine according to an intake air flow rate, An on-time measuring means for measuring an elapsed time from turning on the power to the temperature-sensitive flow meter; an off-time measuring means for measuring an elapsed time after the power supply to the temperature-sensitive flow meter is cut off; A conversion unit that converts a detection signal from the flow meter into a value equivalent to the intake air flow rate, and a conversion characteristic of the conversion unit is corrected based on the elapsed time measured by each of the on-time measuring unit and the off-time measuring unit. An intake air flow rate detection device for an internal combustion engine, comprising: a correction means based on an on / off time. 2. A temperature sensitive flow meter for outputting a detection signal corresponding to an engine intake air flow rate based on a resistance value change of a temperature sensitive resistance arranged in an intake passage of an internal combustion engine according to an intake air flow rate, An on-time measuring means for measuring an elapsed time from power-on of the temperature-sensitive flow meter, and a power-on level detecting means for sampling a detection signal output immediately after power-on of the temperature-sensitive flow meter, Conversion means for converting a detection signal from the temperature-sensitive flow meter into an intake air flow rate equivalent value, and conversion characteristics in the conversion means, the elapsed time measured by the on-time measuring means, and the power-on level detection means An intake air flow rate detection device for an internal combustion engine, comprising: an on-time and a power-on level correction means for making corrections based on the detection signal sampled in. 3. A temperature-sensitive flow meter, which outputs a detection signal corresponding to an engine intake air flow rate based on a resistance value change of a temperature-sensitive resistance arranged in an intake passage of an internal combustion engine according to an intake air flow rate, An on-time measuring means for measuring an elapsed time from turning on the power to the temperature-sensitive flow meter, and an intake air flow rate in which a detection signal of the temperature-sensitive flow meter is a predetermined value or more at an initial stage of power-on to the temperature-type flow meter. The erroneous detection time measuring means for measuring the time at which the value of is indicated, the converting means for converting the detection signal from the temperature-sensitive flow meter into the intake air flow rate equivalent value, and the conversion characteristic in the converting means are An internal combustion engine, comprising: an on-time and an erroneous detection time correcting means for correcting the time based on the elapsed time measured by the on-time measuring means and the time measured by the erroneous detection time measuring means. Engine intake air flow rate test Apparatus.