JPH08145754A - Intake air flow measuring device for internal combustion engine - Google Patents

Abstract

PURPOSE: To provide a measuring device capable of precise counterflow detection by providing, between a detecting part and a flow rate arithmetic part, a modulating means for changing the amplitude of the output signal from the detecting part and outputting the resulting signal. CONSTITUTION: Heating coil driving circuits 1, 2, which are independent circuits, respectively, are connected to a power source 10 to independently make outputs according to an air flow rate. The heating coil driving circuit 1 regulates the current carried to a heating resistor 11 by a differential amplifier 15 and a transistor 16 so that the potential difference in the bridge middle point is zero by a whiston bridge circuit consisting of the heating resistor 11, a temperature compensating resistor 12, and resistors 13, 14. The respective outputs according to the air quantity of the heating resistors 11, 21 are electrically improved in frequency responsiveness, the direction of the air flow is detected according to the difference in magnitude of the outputs of equalizer circuits 3, 4 by a voltage comparator 5, and the outputs of the equalizer circuits 3, 4 are switched by a switch circuit 6 and outputted as a flow rate signal with little counterflow error.

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 measuring device for an internal combustion engine, and more particularly to an intake air amount measuring device for an internal combustion engine suitable for detecting backflow.

[0002]

2. Description of the Related Art Conventionally, as an air flow meter provided in an electronically controlled fuel injection device for an internal combustion engine of an automobile or the like, which measures the intake air amount, a hot wire type has become mainstream because it can directly detect the mass air amount. Ori, SAE paper 800
The ones described in 468,830615 have been put to practical use. Also,
As in the case of low engine speed of 4 cylinders or less and heavy load,
In the case of a pulsating flow with a large pulsation amplitude of the intake air amount and a partial backflow, the accuracy of the conventional hot-wire air flowmeter decreases, so that the one described in JP-A-62-821 and JP-A-62-821. 73
Those described in Japanese Patent No. 124 have been devised.

[0003]

In the above-mentioned prior art, when the intake valve, which is called backflow during pulsation, overlaps, the air blows back from the exhaust valve side to the intake valve side at a positive pressure as the piston rises when the intake valve overlaps. Is measured by a conventional hot-wire air flow meter, the signal outputs a positive signal corresponding to the absolute value of the flow velocity regardless of the direction of forward flow and reverse flow. Therefore, when the backflow occurs, the signal is as if it were a forward flow, and a signal larger than the true average air flow rate is output. There is a problem that the measurement error at this time reaches 30 to 100%. In addition, if a special hot-wire probe that can detect forward flow and reverse flow separately at high speed is used, the direction is detected from the difference between the forward and reverse flow air flow rates, and the air flow rate is output according to the direction. Can be reduced. However, since a special hot-wire probe that can detect forward flow and reverse flow separately at high speed is required, there are problems that the manufacturing cost of the probe increases and the reliability decreases.

An object of the present invention is to provide an intake air amount measuring device for an internal combustion engine, which can detect backflow with high accuracy.

[0005]

The above-mentioned object can be achieved by providing a modulation means for changing the amplitude of the output signal from the detecting section and outputting the signal between the detecting section and the flow rate calculating section.

[0006]

By electrically recovering the response delay of the heat ray signal including the response delay by the equalizer circuit, and switching between the two forward and reverse heat ray signal outputs that have recovered the response delay based on the detected direction signal, A backflow-corrected heat ray signal close to the true air flow rate itself can be obtained, and the error in the average air flow rate can be made extremely small.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The heat-wire drive circuits 1 and 2 are independent circuits, respectively, which are connected to the power supply 10 and separately output according to the air flow rate. The heat wire drive circuit 1 is a Wheatstone bridge circuit including a heating resistor 11, a temperature compensating resistor 12, and resistors 13 and 14, and a heating resistor 1 is provided by a differential amplifier 15 and a transistor 16 so that the potential difference at the bridge midpoint becomes zero.
It is configured to regulate the current flowing through 1. With this configuration, the resistance value of the heating resistor 11 is controlled to be constant regardless of the air flow rate, that is, the temperature is controlled to be a constant value. At this time, the signal corresponding to the air flow velocity by the heating resistor 11 is the potential at point A in the figure. In addition, the heat ray drive circuit 2
The same applies to the heating resistor 21 of No. 2, and the signal corresponding to the air flow velocity by the heating resistor 21 is the potential at point B in the figure.

The heating resistors 11 and 21 have a cylindrical or cylindrical bobbin made of an insulating material having good thermal conductivity, such as ceramics, and a platinum or tungsten heating wire is wound around the surface of the bobbin. The coating material is glass or ceramics. The heating resistors 11 and 21 may be formed by forming a thin film or a thick film of platinum or tungsten as a heating element on a substrate such as plate-shaped glass or ceramic.

The heating resistors 11 and 21 are provided in the intake passage of an internal combustion engine such as an automobile. For example, the heating resistor 11 is provided upstream of the intake air and the heating resistor 21 is provided downstream of the intake air. Are arranged in parallel. Heating resistors 11, 21
Like the normal constant temperature type hot wire anemometer, the temperature is electrically heated by the hot wire drive circuits 1 and 2 so that the difference from the air temperature becomes a constant value regardless of the air flow speed. First, when the air flows in the forward direction from the intake upstream side to the downstream side, the heating resistor 11 is cooled by the airflow more than the air flow in the heating resistor 11, so that the current supplied from the heat wire drive circuit 1 is generated by the heating resistor 11. Is greater than 21. On the other hand, when air flows in the opposite direction from the downstream side of the intake air to the upstream side, cooling by the air flow is larger in the heating resistor 21 than in the previous case, and the current supplied from the heat wire drive circuit 2 is the heating resistor 21. Is greater than 11. Therefore, the direction of the air flow can be detected by the difference in the magnitude of the current supplied to the heating resistors 11 and 21. However, air pulsation occurs in the intake passage, and the heating resistor 11,
If a response delay occurs in the heat ray drive circuits 1 and 2 due to the thermal response characteristic of 21, the detection of the direction of the air flow is delayed, and an error occurs in the detection of the average air flow rate.

In this embodiment, the outputs corresponding to the respective air flow rates of the heating resistors 11 and 21 are output to the equalizer circuit 3,
4, the frequency response is improved electrically and the voltage comparator 5
The direction of the air flow is detected by the difference between the outputs of the equalizer circuits 3 and 4, and the output of the equalizer circuits 3 and 4 is switched by the switch circuit 6 and output as a flow rate signal with less backflow error. The switch circuit 6 switches the outputs of the equalizer circuits 3 and 4 by inverting the output signal of the equalizer circuit 4 on the backflow side by the inverting circuit 61. In this case, it is possible to interface with the engine control unit only by the output signal without outputting the direction signal to the outside. The switch circuit 6 used here is, for example, an analog switch manufactured by a CMOS process, an analog switch using a transistor manufactured by a bipolar process, or the like, and is not particularly limited.

Next, the detailed operation when the equalizer circuits 3 and 4 are used will be described with reference to FIG. Here, all the heat ray signals are converted into the air flow rate and displayed. Generally, the air flow rate is a sine wave with a negative air flow rate called a reverse flow, as shown in FIG. The waveform is close to. For example, the engine speed is 1000rp
In the case of m, the pulsation frequency is about 33 Hz. Such a phenomenon varies depending on the shape of the combustion chamber of the engine, the shape of the intake and exhaust pipes, the shape of the air cleaner, and the like.

When the pulsating flow accompanied by the backflow is measured by using a special heat ray probe used in a measuring instrument having a fast response as a resistance heating element, it is found that the flow is in the forward flow direction and the reverse flow direction as shown in FIG. 2 (2). A positive signal corresponding to the absolute value of the flow velocity is output regardless. Since the responsiveness to the flow rate is good, the heat ray signal becomes almost zero when switching between forward flow and reverse flow. If two special heat ray probes capable of such a high-speed response are used to detect the forward flow direction and the backward flow direction and synthesize the waveform, the heat ray signal closest to the true air flow rate can be obtained. However, a special heat ray probe used for a measuring instrument having a quick response is expensive, and it is difficult to constantly use it for a machine with large vibration such as an engine of an automobile from the viewpoint of reliability.

Therefore, two heating wire probes, which are conventionally used for measuring the air flow rate of an automobile and which are highly reliable but not particularly responsive, are arranged in parallel and the heating resistors 11 and 2 are arranged in parallel.
When used as 1, a positive signal corresponding to the absolute value of the flow velocity is output regardless of the direction of forward flow and reverse flow, as shown in FIG. In this case, since the response delay occurs, the heat ray signal does not become zero when switching between forward flow and reverse flow. The output A of the heating resistor 11 arranged on the intake upstream side is
Large during forward flow and small during reverse flow. On the contrary, the output B of the heating resistor 21 arranged on the downstream side of the intake air is large during backflow and small during forward flow. As a result of comparing these two signals by the voltage comparator 5, a high potential level (Hi) indicating a forward flow and a low potential level (Low) indicating a reverse flow as shown in FIG. 2 (4) are repeated. The switching circuit 6 performs forward / reverse switching using a direction signal to perform backflow correction, and the heat ray signal shown in FIG.
The composite waveform is accompanied by backflow as shown in (5). However, since the phase shifts with respect to the true air flow rate, and the waveform near the zero air flow rate jumps, an error will occur if the average air flow rates are compared and simply combining using the direction signal. .

In the present embodiment, the heat ray signal including the response delay shown in FIG. 2C is electrically recovered by the equalizer circuits 3 and 4 as shown in FIG. . Two forward and reverse heat ray signal outputs A2 that have recovered the response delay
B2 is adjusted by the equalizer circuits 3 and 4 so that the phase and the amplitude are close to the true air flow rate. By using these new signals A2 and B2, a direction signal is newly generated and outputs are switched and combined to obtain a backflow-corrected heat ray signal close to the true air flow rate itself as shown in FIG. 2 (7). Therefore, the error of the average air flow rate can be made very small.

FIG. 3 shows an example of frequency characteristics of the equalizer circuits 3 and 4. This represents the electrical frequency response of the heat ray drive circuits 1 and 2 including the heating resistors 11 and 21 at a certain constant flow rate. Regarding the responsiveness of the heat ray drive circuit, the cutoff is approximately several tens Hz and 100 Hz or less. For example, the engine speed is from 1000 rpm to 20
In the case of the air flow rate at 00 rpm, a pulsation frequency of about 33 Hz to about 66 Hz is generated, so that the cutoff of the heat wire drive circuit is affected and a response delay occurs in the detected value of the air flow rate. However, for example, if the characteristics of an equalizer having a phase lead element as shown in FIG. 3 are added, the synthesized response is, for example, several hundred Hz, and a response that is an order of magnitude faster than the response of only the heat ray drive circuit is realized. You can do it. In this case, it is desirable that the synthesized response gain characteristic be such that only the frequency extends while remaining flat. As a result, the delay in detecting the air flow rate can be eliminated.

FIG. 4 shows an embodiment in which the equalizer circuits 3 and 4 are specifically realized by electric circuits. This uses a differential amplifier 31, the resistors 33, 34, 36, 38 determine the input / output gain, and the resistor 37, capacitors 32, 35.
Determines the frequency characteristic of the phase lead element.

According to this embodiment using the above equalizer circuit, the response can be easily improved with a simple circuit without using a special heat ray probe as a resistance heating element.
The accuracy of measuring the average air flow rate can be improved relatively easily. Further, since the responsiveness of the heat ray drive circuit is electrically improved, there is an effect that the rising characteristic at the time of starting the power supply can be made faster than before.

A second embodiment of the present invention will be described with reference to FIG. In this embodiment, in the embodiment shown in FIG. 1, the true flow rate is measured in consideration of the backflow by eliminating the inverting circuit and using the output signal and the direction signal to determine the forward flow and the backflow on the engine control unit side. be able to. According to this embodiment, since the dynamic range of the forward flow and the reverse flow of the output signal can be widened, the A in the engine control unit
The detection accuracy of the / D converter is improved.

A third embodiment of the present invention will be described with reference to FIG. For example, when the pulsation amplitude of the intake air amount is relatively small due to the shape of the combustion chamber of the engine, the shape of the intake / exhaust pipe, and the shape of the air cleaner, but a backflow occurs, the response may be more The error due to the delay in the detection of the forward and backward flow direction signals due to the delay may be more problematic. In the present embodiment, equalizer circuits 3 and 4 are provided at the outputs of the heat ray drive circuits 1 and 4 and are input only to the voltage comparator 5 to exclusively detect the direction signal. The output signals A and B are switched by the switch circuit 6 to obtain a backflow-corrected flow rate output signal. In the case of the present embodiment, since the outputs of the equalizer circuits 3 and 4 are not directly used for the flow rate output signal, the amplitude characteristics of the equalizer circuits 3 and 4 are not calibrated in accordance with the heat ray drive circuits 1 and 2, Does not directly affect flow rate detection.
If the amplitude characteristic is not taken into consideration, the equalizer circuits 3 and 4
The phase lead element can be easily constructed by passive components such as resistors and capacitors instead of the active components such as the differential amplifier shown in FIG. Here, an embodiment of an equalizer circuit using passive components will be described with reference to FIG.
This is a low-pass filter (low-pass filter) including a resistor 41 and a capacitor 42, and resistors 43, 44, 4
6, with a phase lead circuit consisting of a capacitor 45,
It is intended to improve the AC amplitude characteristic. Although the DC gain is reduced in the present embodiment, it can be used as an equalizer circuit for direction detection by changing only the AC amplitude characteristic.

According to this embodiment, in order to further reduce the error due to the delay in detecting the forward and backward flow direction signals, the amplitude characteristics of the equalizer circuits 3 and 4 are set to be larger than the amplitude of the true air flow rate. It is also possible to increase the detection sensitivity of the direction signal at the time of reverse flow. According to this embodiment, the backflow can be detected with high sensitivity even when the pulsation of the air flow rate or the backflow is small, and the more accurate measurement of the air flow rate becomes possible. Further, the time constants of the equalizer circuits 3 and 4 can be easily set, the accuracy of the resistors and capacitors that determine the time constant can be lowered, and no extra adjustment is required.

A fourth embodiment of the present invention will be described with reference to FIG. For example, the backflow of the intake air amount is small, but the pulsation amplitude is relatively large, and the error in the average value of the intake air amount due to the pulsation amplitude may be more problematic than the error in the air flow rate due to the occurrence of the backflow. In the present embodiment, the outputs of the heat ray drive circuits 1 and 2 are input to the voltage comparator 5 to detect the direction signal, and the air flow rate is switched by the switch circuit 6 between the output signals A and B of the heat ray drive circuits 1 and 2. After the backflow correction, the pulsation amplitude is corrected via the second equalizer circuit 7 to obtain the flow rate output signal again. In the case of this embodiment, since the pulsation amplitude can be freely set by using the second equalizer circuit 7, the correction of the average air flow rate can be made positive or negative.

FIG. 9 shows an example of frequency characteristics of the second equalizer circuit 7. This represents the electrical frequency response of the heat ray drive circuits 1 and 2 including the heating resistors 11 and 21 at a certain constant flow rate. Here, the frequency characteristic of the second equalizer with respect to the response of the heat ray drive circuit is synthesized by adding a phase lead element as shown in FIG. 9 gradually while the response of the heat ray drive circuit is flat. The response can be such that the gain gradually increases from several tens Hz and the cutoff frequency becomes 100 Hz or higher. When the second equalizer circuit 7 is used, it is possible to recover the amplitude decrease at the time of pulsation due to the response delay when the pulsation occurs in the air flow rate by changing the gain characteristic. It is possible to reduce the measurement error when viewed.

FIG. 10 shows an embodiment in which the second equalizer circuit 7 is specifically realized by an electric circuit. this is,
In the circuit of the equalizer circuit 3 described with reference to FIG. 4, network resistors 91, 92 for changing the input / output gain,
93 and 94 and capacitors 95 and 96 are added. By adjusting the value of the resistor 93, the gain characteristic of the second equalizer circuit 7 can be changed. The basic characteristic of the circuit itself is that the differential amplifier 71 is used and the resistors 73 and 7 are used.
4, 76 and 78 determine the input / output gain, and the resistor 77 and the capacitors 72 and 75 determine the frequency characteristic of the phase lead element.

In the present embodiment, especially the second equalizer circuit 7
If is used, it is possible to adjust the relationship of the air flow rate with respect to the throttle opening so as to monotonically increase with a small circuit configuration, and there is an effect that matching with the engine control unit of the automobile is improved. A fifth embodiment of the present invention will be described with reference to FIG. For example, when both the pulsation amplitude and the backflow of the intake air amount are large and the pulsation contains many harmonic components, the detection error of the intake air amount due to the response delay of the heat ray drive circuits 1 and 2 may be particularly large.

In the present embodiment, the outputs of the heat ray driving circuits 1 and 2 are provided with equalizer circuits 3 and 4 and are inputted only to the voltage comparator 5 so as to be exclusively used for detecting the direction signal, and the air flow rate is set to the heat ray driving circuit 1. , 2 output signals A and B are applied to the switch circuit 6
The second equalizer circuit 7
The pulsation amplitude is corrected via and the flow rate output signal is obtained again. In the case of the present embodiment, the response delay of the backflow detection when the backflow is generated is dealt with by the equalizer circuits 3 and 4, and the detection sensitivity can be increased,
Further, by using the second equalizer circuit 7, it is possible to recover the pulsation amplitude by using the second equalizer circuit 7 to reduce the pulsation amplitude due to the response delay when the pulsation occurs, and it is possible to comprehensively reduce the detection error of the intake air amount.

According to the present embodiment, the backflow can be detected with high sensitivity even when the pulsation of the air flow rate or the backflow is greatly disturbed.
It becomes possible to measure the air flow rate more accurately. Since the backflow and pulsation sensitivities can be set separately, adjustment by combining with the engine is easy.

A sixth embodiment of the present invention will be described with reference to FIG. In this embodiment, the heating resistors 11 and 21 of the bridge circuits in the heat ray drive circuits 1 and 2 are arranged on the ground side, and the temperature compensating circuit 8 is provided so that the two bridge circuits can be connected to each other.
It can be configured with only one temperature compensation resistor. The temperature compensating circuit 8 synchronizes a temperature compensating resistor 81 and a resistor 82, which are one side of the bridge circuit, with the heat wire driving circuits 1 and 2 by a clock by an oscillator 89 and switch circuits 88, 84 and 86 which operate by the clock signal thereof. Then, the operation is switched to time division. At this time, the transistor 1 in the heat ray drive circuits 1 and 2 switched by the switch circuit 88
In order to reduce the voltage fluctuation due to the switching of the potentials of the emitter side of 6, 26, the differential amplifier 87 is used as a buffer, and the current is supplied by connecting to the resistor 82 connected in series with the temperature compensating resistor 81 on the ground side. There is. The output of the temperature compensation resistor 81 is the switch circuits 84, 86 and the capacitors 83, 8
The sample-hold circuit constituted by 5 continuously inputs the differential amplifiers 15 and 25 in the heat ray drive circuits 1 and 2, respectively, and operates as independent bridge circuits. In order to stabilize the operation of the heat ray drive circuits 1 and 2, it is desirable to provide capacitors 17 and 27 in parallel with the heating resistors 11 and 21.

The outputs of the heat ray drive circuits 1 and 2 are input to the voltage comparator 5 to detect the direction signal, and the air flow rate is switched by the switch circuit 6 between the output signals A and B of the heat ray drive circuits 1 and 2. A flow rate output signal can be obtained by performing backflow correction. In the present embodiment, the example in which the equalizer circuit is not used for the output of the heat ray drive circuit has been described, but various equalizer circuits may be used in combination with the switching of the direction signal and the flow rate output signal.

According to this embodiment, since the relatively expensive temperature compensating resistor which is normally provided in the intake passage together with the two heating resistors can be reduced to one, the cost can be reduced. Also, since only one temperature adjustment point is required for the two bridge circuits, the number of temperature compensation resistors is reduced to one, and the number of assembly steps during manufacturing can be reduced and the production cost during mass production can be reduced.

The seventh embodiment of the present invention will be described with reference to FIG. In this embodiment, the outputs of the heat ray drive circuits 1 and 2 are provided to the voltage comparator 5 by providing the equalizer circuits 3 and 4, and the direction signal is exclusively used for detection. The output delay is individually recovered by the second equalizer circuit, and the signal is switched by the switch circuit 6 to be the flow rate output signal. In the case of this embodiment, the difference in the frequency response of each sensor can be adjusted individually, so that the accuracy is further improved.

An eighth embodiment of the present invention will be described with reference to FIG. In this embodiment, the equalizer circuit 3 recovers the response delay of the output signal of the heat ray drive circuit 1 and outputs the signal to the flow rate calculation unit 99. In the case of the present embodiment, the accuracy of the air flow rate can be relatively easily improved by providing the equalizer circuit between the detection unit and the flow rate calculation unit.

[0032]

According to the present invention, the average air flow rate can be measured even when the measurement error increases in a hot wire air flow meter using a normal hot wire probe, in which the air flow rate is accompanied by backflow or pulsating flow. There is an effect that the accuracy can be improved relatively easily. Further, there is an effect that the monotonous increase of the air flow rate with respect to the throttle opening can be secured and the matching with the engine control unit used in the electronically controlled fuel injection device of the automobile is improved.

[Brief description of drawings]

FIG. 1 is a heat ray drive circuit diagram using an equalizer circuit according to an embodiment of the present invention.

FIG. 2 is an operation waveform diagram when the intake air flow is a pulsating flow accompanied by backflow.

FIG. 3 is a heat ray drive circuit diagram and a frequency characteristic diagram of an equalizer circuit.

FIG. 4 is an embodiment of an equalizer circuit.

FIG. 5 is a heat ray drive circuit diagram using an equalizer circuit according to an embodiment of the present invention.

FIG. 6 is a heat ray drive circuit diagram using an equalizer circuit according to an embodiment of the present invention.

FIG. 7 is an example of an equalizer circuit.

FIG. 8 is a heat ray drive circuit diagram using a second equalizer circuit according to an embodiment of the present invention.

FIG. 9 is a heat ray drive circuit diagram and a frequency characteristic diagram of a second equalizer circuit.

FIG. 10 is an example of a second equalizer circuit.

FIG. 11 is a heat ray drive circuit diagram using the first and second equalizer circuits according to the embodiment of the present invention.

FIG. 12 is a heat ray drive circuit diagram in which one temperature compensation resistor is used according to an embodiment of the present invention.

FIG. 13 is a heat ray drive circuit diagram in which one temperature compensation resistor according to the embodiment of the present invention is used.

FIG. 14 is a heat ray drive circuit diagram using an equalizer circuit according to an embodiment of the present invention.

[Explanation of symbols]

1, 2 ... Heat ray drive circuit, 3, 4 ... Equalizer circuit, 5 ...
Voltage comparator, 6, 84, 86, 88 ... Switch circuit, 7
... Second equalizer circuit, 8 ... Temperature compensation circuit, 10 ... Power source, 11,21 ... Heating resistor, 12,22,81 ... Temperature compensation resistor, 13,14,23,24,33,34,3
6,37,38,73,74,76,77,78,9
1, 92, 93, 94 ... Resistors, 15, 25, 87 ... Differential amplifiers, 16, 26 ... Transistors, 17, 27, 3
2, 35, 72, 75, 83, 85, 95, 96 ... Capacitor, 89 ... Oscillator, 99 ... Flow rate calculation unit.

Front Page Continuation (72) Inventor Kaoru Uchiyama 2520 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi Ltd. Automotive Equipment Division

Claims (12)

[Claims] 1. An intake air amount measuring device for an internal combustion engine, comprising: a detection unit including a heating resistor; and a flow rate calculation unit that calculates an air flow rate based on an output signal from the detection unit. An intake air amount measuring device for an internal combustion engine, comprising: a modulation means for changing the amplitude of a signal from the detecting section and outputting the signal between the calculating section and the calculating section. 2. The intake air amount measuring device for an internal combustion engine according to claim 1, wherein the modulating means is an equalizer circuit. 3. The equalizer circuit according to claim 2, wherein the equalizer circuit uses a differential amplifier and resistors (33, 34, 36, 38).
The intake air amount measuring device for an internal combustion engine, characterized in that the input / output gain is determined by, and the phase lead element is set by the resistor (37) and the capacitor to determine the frequency characteristic of the input / output gain. 4. The low-pass filter according to claim 2, wherein the equalizer circuit has a low-pass filter composed of a resistor (41) and a capacitor (41), and a resistor (43, 44,46) and capacitors (4
An intake air amount measuring device for an internal combustion engine, wherein an input / output gain and a frequency characteristic of the equalizer circuit are determined by the phase lead circuit configured in 5). 5. The intake air amount measuring device for an internal combustion engine according to claim 1, wherein the detecting unit is a bridge circuit. 6. A bridge circuit including a heating resistor.
In an intake air amount measuring device for an internal combustion engine, comprising one detection unit and a flow rate calculation unit that calculates an air flow rate based on an output signal from the detection unit, the detection unit is provided between the detection unit and the flow rate calculation unit. An intake air amount measuring device for an internal combustion engine, characterized in that modulation means for individually changing the amplitude of a frequency component of an output signal from the section is provided. 7. A bridge circuit including a heating resistor.
In an intake air amount measuring device for an internal combustion engine, comprising one detection unit and a flow rate calculation unit that calculates an air flow rate based on an output signal from the detection unit, the detection unit is provided between the detection unit and the flow rate calculation unit. An intake air amount measuring device for an internal combustion engine, characterized in that modulation means for individually changing a phase of a frequency component of an output signal from the section and outputting the same is provided. 8. A bridge circuit including a heating resistor 2
In an intake air amount measuring device for an internal combustion engine, comprising: one detection unit; and a flow rate calculation unit that calculates an air flow rate based on an output signal from the detection unit, wherein the detection unit is provided between the detection unit and the flow rate calculation unit. Equipped with an equalizer circuit for modulating the output signal from the, the means for detecting the flow direction of the air from the individual output signal modulated by the equalizer circuit, based on the detected flow direction of the air, the equalizer circuit An intake air amount measuring device for an internal combustion engine, comprising means for switching the output of the above and outputting it to the flow rate calculating unit. 9. A bridge circuit including a heating resistor.
In an intake air amount measuring device for an internal combustion engine, comprising: one detection unit; and a flow rate calculation unit that calculates an air flow rate based on an output signal from the detection unit, wherein the detection unit is provided between the detection unit and the flow rate calculation unit. Equipped with an equalizer circuit for modulating the output signal from the, the means for detecting the air flow direction from the individual output signal modulated by the equalizer circuit, based on the detected air flow direction, the bridge circuit An intake air amount measuring device for an internal combustion engine, comprising means for switching the output of the above and outputting it to the flow rate calculating unit. 10. An intake air amount measuring device for an internal combustion engine, comprising: two detecting sections each comprising a bridge circuit including a heating resistor; and a flow rate calculating section for calculating an air flow rate based on an output signal from the detecting section, A first equalizer circuit and a second equalizer circuit that modulate the output signal from the detection unit are individually provided between the detection unit and the flow rate calculation unit, and the individual equalizer circuits modulated by the first equalizer circuit are provided. A means for detecting the flow direction of the air from the output signal is provided, and a means for switching the output of the second equalizer circuit based on the detected flow direction of the air and outputting it to the flow rate calculation unit is provided. Intake air amount measuring device for internal combustion engine. 11. An intake air amount measuring device for an internal combustion engine, comprising: two detecting sections each comprising a bridge circuit including a heating resistor; and a flow rate calculating section for calculating an air flow rate based on an output signal from the detecting section. Between the detection unit and the flow rate calculation unit, detection means for detecting the air flow direction from the output signal of the bridge circuit, and the output of the bridge circuit based on the air flow direction detected by the detection means An intake air amount measuring apparatus for an internal combustion engine, comprising: a switching unit for switching between the two and an equalizer circuit for modulating an output signal of the bridge circuit switched by the switching unit. 12. An intake air amount measuring device for an internal combustion engine, comprising: two detecting sections each comprising a bridge circuit including a heating resistor; and a flow rate calculating section for calculating an air flow rate based on an output signal from the detecting section, Between the detection unit and the flow rate calculation unit, each equalizer circuit that modulates the output signal from the detection unit, and a detection unit that detects the flow direction of air from each output signal modulated by the equalizer circuit. An internal combustion engine having switching means for switching the output of the bridge circuit based on the detected flow direction of air, and an equalizer circuit for modulating the output signal of the bridge circuit switched by the switching means. Intake air amount measuring device.