JPH07234143A - Intake air flow rate detector of internal combustion engine - Google Patents

Abstract

PURPOSE:To ensure the reliability of a detector by enhancing the detection accuracy of the flow rate of intake air even when intake air pulsation containing a back flow component is generated. CONSTITUTION:An intake air passage 13 is divided into an intake air passage 13a permitting only forward flow to pass and an intake air passage 13b permitting only back flow to pass by a central partition wall 21 and shield walls 22, 23 and the temp.-sensitive resistor RH1 incorporated in a circuit outputting only forward direction output is arranged to the intake air passage 13a and the temp.-sensitive resistor RH2 incorporated in a circuit outputting only reverse direction output is arranged to the intake air passage 13b.

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 device for detecting the intake air flow rate of an engine in consideration of the intake air flow rate flowing in a reverse flow direction.

[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 an intake air flow rate Q of the engine, and the intake air flow rate Q detected by this air flow meter is A configuration is known in which a basic fuel injection amount Tp = K × Q / Ne (K is a constant) by a fuel injection valve is calculated from the engine rotation speed Ne, and the air flow meter is disclosed in Japanese Patent Application Laid-Open No. 4-95721. A temperature-sensitive flow meter as disclosed in the official gazette is used.

In the temperature-sensitive flowmeter, 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 by increasing the current, and the intake air flow rate is obtained from the current value. That is, the temperature-sensitive flow meter 1 in FIG. 7 will be described 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 sensing resistor R of the bridge circuit B
_H and the reference resistance R _s are connected in series, the potential of the voltage dividing point (the terminal voltage of the reference resistance R _s ) and the temperature compensation resistance R
_K and the potential at the voltage dividing point on the side where the fixed resistors R _{1 and} R ₂ are connected in series (the terminal voltage of the fixed resistor R ₂ ) are input to the differential amplifier OP. 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 a balanced state,
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.

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 is also cooled. Since the resistance value is reduced, the current value supplied to the bridge circuit B is suppressed from changing due to the temperature change of the intake air. Therefore, the intake air flow rate Q 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 Q is measured by detecting the terminal voltage Us of the reference resistance R _s. It is possible to do.

In the example shown in FIG. 7, the terminal voltage Us of the reference resistor R _s is A / D converted by the A / D converter 3 and the control unit includes a microcomputer.
Let it read in 16. Here, the control unit 16
A table for converting the terminal voltage Us into the intake air flow rate Q is provided in advance, and the terminal voltage U is converted by using the table.
The information of s is converted into the intake air flow rate Q to detect the intake air flow rate Q of the engine. Then, the amount of fuel to be injected and supplied from a fuel injection valve (not shown) is determined based on the information of the intake air flow rate Q, and an air-fuel mixture having a predetermined air-fuel ratio is formed.

In FIG. 7, reference numeral 2 is an ignition switch, and a battery voltage VB is applied to the temperature-sensitive flow meter 1 and the control unit 16 via the ignition switch 2.

[0009]

By the way, when the throttle valve opening is large and the engine speed is in the low speed region or the high speed region, the intake pulsation including the backflow component is applied to the temperature sensitive flowmeter from the cylinder side. It may reach the temperature-sensitive resistance R _H. At this time, since the temperature-sensitive resistance R _H cannot determine the flow direction, the backflow is detected in the same manner as the positive direction (see FIG. 8), and as a result, the average flow rate is lower than the true intake air flow rate (see FIG. 9). There was a problem that a large value would be detected.

As described above, when the detected value of the intake air flow rate becomes larger than the true intake air flow rate, the extra fuel is injected and supplied by the electronic fuel injection control based on the detected value. The air-fuel ratio will be made richer than the target air-fuel ratio. Here, as a device for measuring the air flow rate related to the intake pulsation including the backflow component, as shown in Japanese Patent Publication No. 4-32328, upstream and downstream of the measured resistance whose resistance value changes according to the intake air flow rate. There is a device that measures the air flow rate related to the intake pulsation that includes a backflow component based on the difference between the outputs of both detection resistors, but there is a device that requires complicated calculation correction to ensure reliability. Difficult to do.

In the above description, the problem has been explained by taking the temperature sensitive flow meter as an example. However, the intake air flow rate detecting portion is acted upon by the intake pulsation containing the backflow component, so that the intake air flow rate is detected. It goes without saying that an erroneous intake air flow rate is detected by the air flow rate detection unit. The present invention has been made in view of the above problems, and even if intake pulsation including a backflow component occurs, it is possible to prevent the backflow of the intake air from being transmitted to the intake air flow rate detection unit, thereby reducing the intake air flow rate. The object is to improve the detection accuracy and ensure the reliability of the intake air flow rate detection device.

[0012]

Therefore, as a means according to claim 1 of the present invention, in an intake air flow rate detecting device for detecting the intake air flow rate of an internal combustion engine, only the intake air flow rate component flowing in the forward flow direction is detected. Forward flow component detecting means, reverse flow component detecting means for detecting only the intake air flow rate component flowing in the reverse flow direction, and detecting the intake air flow rate of the engine based on the forward flow component detection value and the reverse flow component detection value of the intake air flow rate And an intake air amount detecting means for controlling the intake air amount.

Further, as means according to claim 2 of the present invention,
In the intake air passage of the internal combustion engine, a forward flow component passage means for blocking the reverse flow component of the intake air flow and passing only the forward flow component,
Backflow component passing means for blocking the forward flow component of the intake air flow and passing only the backward flow component, and passing the forward flow component detecting means and the backward flow component detecting means through the forward flow component passing means and the backward flow component passing means, respectively. It may be configured by detecting the flow rates of the forward flow component and the reverse flow component.

Further, as means according to claim 3 of the present invention,
The forward flow component passing means and the backward flow component passing means are respectively forward flow,
Open the inlet to the backflow at a right angle to the direction of the intake air flow,
It may be configured by opening the outlet in parallel with the intake air circulation direction. Further, as a means according to claim 4 of the present invention, the intake air flow rate detecting device for detecting the intake air flow rate may be a temperature-sensitive resistance type.

[0015]

According to the intake air flow rate detecting device having the above-described structure, as the action of the invention described in claim 1, when the intake pulsation including the backflow component is generated, the intake component flowing in the normal flow direction by the normal flow component detecting means. Only the air flow rate component is detected, and the backflow component detection means detects only the intake air flow rate component flowing in the backflow direction.

Then, the intake air amount detecting means detects the intake air flow rate of the engine based on the detected value of the forward flow component and the detected value of the reverse flow component of the intake air flow rate. Further, as an operation of the invention described in claim 2, when the forward air component passage means and the backward flow component passage means are provided in the intake air passage of the internal combustion engine,
Since the normal flow component passage means blocks the reverse flow component of the intake air flow and passes only the normal flow component, the normal flow component is detected by detecting the flow rate of the normal flow component passing through the normal flow component passage means. In addition, since the backflow component passing means blocks the forward flow component of the intake air flow and allows only the backflow component to pass through, the backflow component passing means detects the flow rate of the backflow component passing through the backflow component passing means. It is possible to detect the backflow component.

As an operation of the invention described in claim 3,
The forward flow component passing means and the backward flow component passing means are respectively forward flow,
Open the inlet to the backflow at a right angle to the direction of the intake air flow,
By opening the outlet in parallel to the intake air flow direction, a forward flow and a reverse flow are likely to enter from the inlet and become difficult to enter from the outlet.
The forward flow component can be reliably blocked, and the forward flow component and the backward flow component can be reliably passed.

As an operation of the invention according to claim 4,
When the intake air flow rate detection device that detects the intake air flow rate is a temperature-sensitive resistance type, when intake pulsation including a backflow component is occurring, the intake airflow component and the backflow direction that flow in the forward direction due to the temperature-sensitive resistance The intake air flow rate component flowing in the engine is detected, and the intake air flow rate of the engine is detected based on the normal flow component detection value and the reverse flow component detection value.

[0019]

EXAMPLE An example of the present invention will be described below. The present embodiment is an example in which a temperature-sensitive flow meter is used as the flow meter. The circuit configuration of the temperature-sensitive flow meter is almost the same as the circuit configuration described in the conventional example, and the same components are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a system diagram showing an arrangement state of temperature-sensitive resistors R _H1 and R _H2 in the present embodiment with respect to an engine.
An electromagnetic fuel injection valve 15 is provided downstream of the throttle valve 14 in the intake passage 13 from the air cleaner 12 in the engine 11, and the fuel injection valve 15 includes a control unit 16
From the drive pulse signal output from the engine in synchronization with the engine rotation, the valve is opened for the pulse width and fuel injection is performed.

In the intake passage 13 upstream of the throttle valve 14,
Temperature-sensitive resistors R _H1 and R _H2, which respectively constitute the temperature-sensitive flowmeter 1 shown in FIGS. 2 and 3, are interposed, and the temperature-sensitive resistors R _H1
And signals from R _H2 are input to the control unit 16. In addition, a signal is also input to the control unit 16 from a crank angle sensor 18 that also serves as a means for detecting the engine speed N.

Here, as a characteristic configuration of this embodiment, the intake passage 13 upstream of the throttle valve 14 is provided with the intake passage 13.
A central partition 21 that divides 13 in parallel is provided. Further, at the downstream end 21a of the central partition wall 21, the shielding wall 22 is extended to the vicinity of the intake passage wall 25 on the side of one of the divided intake passages 13a, and at the upstream end 21b of the central partition wall 21, the shielding wall 22 is provided. 23 is extended to the vicinity of the intake passage wall 26 on the side of the other divided intake passage 13b.

According to this structure, the intake air flowing from the air cleaner 12 into the intake passage 13 in the forward flow direction has a central partition wall.
Since the shielding wall 23 provided at the upstream end 21b of 21 extends to the vicinity of the intake passage wall 26 on the intake passage 13b side, it passes through the intake passage 13a side without passing through the intake passage 13b side. Inhaled by the engine 11. A blocking wall 22 is provided at the downstream end 21a of the central partition wall 21 on the intake passage 13a side.
Since it is extended to the vicinity of the intake passage wall 25 on the side, the air flowing out to the intake passage 13 in the reverse flow direction does not pass through the intake passage 13a side.

That is, the intake passage 13a functions as a normal flow component passage means. On the other hand, in the air flowing out from the engine 11 to the intake passage 13 in the reverse flow direction, the shielding wall 22 provided at the downstream end 21a of the central partition wall 21 extends to the vicinity of the intake passage wall 25 on the intake passage 13a side. The intake passage 13a
It does not pass on the side, but on the side of the intake passage 13b. Further, on the intake passage 13b side, the blocking wall 23 is extended to the vicinity of the intake passage wall 26 on the intake passage 13b side at the upstream end 21b of the central partition wall 21, so that the flow direction from the air cleaner 12 to the intake passage 13 is increased. The intake air that flows in is taken in by the intake passage 13b.
Never pass by.

That is, the intake passage 13b functions as a backflow component passing means. And the temperature-sensitive resistor R
_H1 is the upstream end 21 of the central partition wall 21 in the one intake passage 13a.
The temperature-sensitive resistor R _H2 is disposed near b and near the downstream end 21a of the central partition wall 21 in the other intake passage 13b. Next, a circuit configuration to which the temperature sensitive resistor R _H1 and the temperature sensitive resistor R _H2 are connected will be described. Note that the configuration and operation of the temperature-sensitive flow meter 1 shown in FIG. 7 are almost the same, so a brief description will be given here.

The circuit shown in FIG. 2 is a circuit that outputs an output of the temperature-sensitive resistor R _H1, by connecting the temperature sensitive resistor R _H1 in place of the temperature sensitive resistor R _H in the circuit,
Temperature sensitive resistor R _H1, in a state where the bridge circuit B is balanced, for example, the intake air flow rate of the engine is increased, the temperature-sensitive resistor R _H1 is the resistance value decreases is more cooled by the air flow, The terminal voltage of the reference resistor 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 _H1 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 falls, for example, the temperature-sensitive resistor R _H1 is cooled and its resistance value decreases, but the temperature-compensating resistor R _{K in the} same atmosphere as the temperature-sensitive resistor R _H1.
At the same time, the resistance value of the bridge circuit B is reduced and the resistance value of the bridge circuit B is reduced, so that the current value supplied to the bridge circuit B is prevented from changing due to the temperature change of the intake air. Therefore, the intake air flow rate Q of the engine and the current supplied to the bridge circuit B correspond independently of the intake air temperature, and the temperature-sensitive resistance R _H1 is detected by detecting the terminal voltage Us of the reference resistance R _s. It is possible to detect the amount of air passing through.

Therefore, the temperature-sensitive resistor R _H1 is connected to the intake passage 13a.
The amount of intake air flowing from the air cleaner 12 into the intake passage 3 in the forward flow direction is detected through the temperature sensor R
_{As for H2} , a forward output as shown in FIG. 4 is output based on the change in the resistance value of the temperature-sensitive resistor R _H1 according to the amount of intake air flowing in the intake passage 13a in the forward direction. That is, FIG.
The circuit shown in (1) functions as a forward current component detecting means.

On the other hand, the circuit shown in FIG. 3 is a circuit for outputting an output of the temperature-sensitive resistor R _H2, by connecting the temperature sensitive resistor R _H2 instead of the temperature sensitive resistor R _H in the circuit , the temperature sensitive resistor R _H2, in the state in which the bridge circuit B 'are balanced, for example, an air flow rate of air flowing in the reverse flow direction to the intake passage 13 from the engine 11 is increased, the temperature-sensitive resistor R _H2 is the air The current is further cooled, its resistance value decreases, 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 decreases to the negative side (changes to increase in absolute value), the temperature-sensitive resistor R _H2 is heated, and its resistance value increases. By doing so, 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 _H2 is cooled and its resistance value decreases, but the temperature-compensating resistor R _{K in the} same atmosphere as the temperature-sensitive resistor R _H2.
At the same time, the resistance value of the bridge circuit B'is reduced and the resistance value of the bridge circuit B'is prevented from changing due to the temperature change of the intake air. Therefore, by the current supplied to the intake air flow rate Q and the bridge circuit B of the engine 'is to correspond independently to an intake air temperature, detecting a terminal voltage Us of the reference resistor R _s, the temperature sensing resistor R It becomes possible to detect the amount of air passing through _H2 .

Therefore, the temperature-sensitive resistor R _H2 is connected to the intake passage 13b.
The amount of air flowing out to the intake passage 3 in the reverse flow direction is detected, and the temperature-sensitive resistance R _H2 is based on the resistance value change of the temperature-sensitive resistor R _H2 corresponding to the amount of air flowing in the intake passage 13b in the reverse flow direction. As a result, a negative output is output as shown in FIG. That is, the circuit shown in FIG. 3 functions as a backflow component detecting means.

Further, in the present embodiment, the positive direction output and the negative direction output are input to the adder (not shown), and the positive flow component as shown in FIG. An output is obtained in which the components are output in the negative direction. Thereafter, as in the conventional case, the output is A / D converted by the A / D converter 3 and read into the control unit 16, and the control unit 16 is provided with a table for converting the terminal voltage Us into the intake air flow rate Q in advance. The information of the terminal voltage Us is converted into the intake air flow rate Q using the table to detect the intake air flow rate Q of the engine.

That is, the structure corresponds to intake air amount detecting means for detecting the intake air flow rate Q of the engine based on the detected value of the forward flow component and the detected value of the reverse flow component of the intake air flow rate. In this way, the intake air flow rate is calculated using the output in which the positive flow component is output in the positive direction and the reverse flow component is output in the negative direction, so the correct reverse flow component is detected, and the reverse flow component is detected. Even if an intake pulsation including the above occurs, it is possible to correctly reflect the occurrence of the backflow in the calculation of the intake air flow rate, and the average flow rate is calculated to be larger than the true intake air flow rate due to the backflow component. This can be avoided, and thus the accuracy of fuel injection control can be improved.

In the embodiment described above, the central partition wall 21, the shielding walls 22 and 23 constitute the forward flow component passing means and the reverse flow component passing means. However, as shown in FIG. , Inlets 41 and 42 are opened at right angles to the forward flow and reverse flow, respectively, and the outlets 43 and 44 are forward flow and reverse flow, respectively. The forward flow component passing means and the reverse flow component passing means may be configured by providing the curved passages 45 and 46 that are opened parallel to the direction.

Also in this case, the temperature sensitive resistor R is provided in the curved passage 45.
_By disposing _H1 and arranging the temperature sensitive resistance R _H2 in the curved passage 46, the temperature sensitive resistance R _H1 flows in the forward flow direction from the air cleaner 12 into the intake passage 3 through the curved passage 45. The amount of intake air can be detected, and the temperature-sensitive resistor R _H2 can detect the amount of air flowing back to the intake passage 3 via the curved passage 46.

Further, in the embodiment described above, the temperature sensitive flow meter is used as the flow meter, but a flap type flow meter or a Karman vortex flow meter may be used as the flow meter. Of course.

[0037]

As described above, according to the first aspect of the invention, when the intake pulsation including the backflow component is generated, the normal flow component detecting means only receives the intake air flow rate component flowing in the normal flow direction. The reverse flow component detection means detects only the intake air flow rate component flowing in the reverse flow direction to detect the intake air flow rate of the engine.Therefore, even when the intake pulsation including the reverse flow component occurs, the reverse flow component is detected. There is an effect that it is possible to avoid that the average flow rate is calculated to be larger than the true intake air flow rate due to the influence of, and thus the accuracy of fuel injection control can be improved.

According to the second aspect of the present invention, by providing the forward flow component passage means and the backward flow component passage means,
Even if the intake pulsation including the backflow component is generated, the normal flow component detecting means can reliably detect the intake air flow rate flowing in the normal flow direction, which further contributes to the improvement of the accuracy of fuel injection control. . According to the third aspect of the invention, there is an effect that the backflow component and the forward flow component can be reliably blocked, and the forward flow component and the backflow component can be reliably passed.

According to the fourth aspect of the present invention, the intake air flow rate component flowing in the forward flow direction and the intake air flow rate component flowing in the reverse flow direction are detected by the temperature-sensitive resistance, and the forward flow component detection value and the reverse flow component detection value are detected. There is an effect that it is possible to detect the intake air flow rate of the engine based on

[Brief description of drawings]

FIG. 1 is a system schematic diagram showing a hardware configuration of an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a circuit configuration of a temperature-sensitive flow meter according to the above embodiment.

FIG. 3 is a circuit diagram showing a circuit configuration of a temperature-sensitive flow meter of the above embodiment.

FIG. 4 is a time chart showing the output in the forward direction in the above-mentioned embodiment.

FIG. 5 is a time chart showing the output in the negative direction in the above embodiment.

FIG. 6 is a schematic diagram showing a hardware configuration of another embodiment of the present invention.

FIG. 7 is a circuit diagram showing a circuit configuration of a conventional temperature-sensitive flow meter.

FIG. 8 is a time chart showing the occurrence of an average flow rate error due to backflow component detection.

FIG. 9 is a time chart showing a true engine intake air flow rate when a backflow component is generated.

[Explanation of symbols]

1 Temperature-sensitive flow meter 2 Ignition switch 3 A / D converter R _H1 Temperature-sensitive resistor R _H2 Temperature-sensitive resistor 11 Engine 13 Intake passage 16 Control unit 21 Central partition wall 22 Shield wall 23 Shield wall

Claims (4)

[Claims] 1. An intake air flow rate detecting device for detecting an intake air flow rate of an internal combustion engine, comprising: a normal flow component detecting means for detecting only an intake air flow rate component flowing in a forward flow direction; and an intake air flow rate component flowing in a reverse flow direction only. And a backflow component detection unit for detecting the intake air flow rate of the engine based on the forward flow component detection value and the backflow component detection value of the intake air flow rate. Intake air flow rate detection device for internal combustion engine. 2. A normal flow component passing means for blocking a reverse flow component of an intake air flow and passing only a normal flow component in an intake air passage of an internal combustion engine, and a normal flow component for blocking a forward flow component of the intake air flow and only a reverse flow component. And a backflow component passing means for passing the backflow component, and the forward flow component detecting means and the backflow component detecting means detect the flow rates of the forward flow component and the backflow component passing through the forward flow component passing means and the backflow component passing means, respectively. The intake air flow rate detecting device for an internal combustion engine according to claim 1, which is configured. 3. The forward flow component passing means and the backward flow component passing means respectively have an inlet opening at right angles to the intake air flow direction and an outlet opening parallel to the intake air flow direction with respect to the forward flow and the reverse flow, respectively. The intake air flow rate detecting device for an internal combustion engine according to claim 2, wherein 4. The intake air flow rate detecting device for an internal combustion engine according to claim 1, wherein the intake air flow rate detecting device for detecting the intake air flow rate is a temperature sensitive resistance type.