JPH1048016A - Heating resistor type air flow measuring device and fuel injection control system for internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide a heating resistor type air flow measuring device with improved measurement accuracy in a low flow rate region. A heating resistor type air flow rate measuring device detects a flow rate of the intake air 20 based on a temperature-sensitive resistor RC whose resistance value changes according to a temperature of the intake air 20 and heat radiation to the intake air 20. The air flow signal V2 output from the drive circuit 5 including the bridge circuit 7 including the heating resistor RH and the feedback circuit 8 for controlling the heat dissipation of the heating resistor RH is converted into the same thermal effect as that of the temperature-sensitive resistor RC. Received temperature sensitive resistor RC2
The correction circuit 6 is provided at the subsequent stage of the drive circuit 5 and includes a temperature-sensitive resistor RC3, and an output signal Vo is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating resistor type air flow measuring device for an automobile, and more particularly to an improvement in temperature characteristics of an air flow measuring device using a temperature sensitive resistor.

[0002]

2. Description of the Related Art Special attention must be paid to the positions of the heating resistor and the temperature-sensitive resistor in a heating resistor type air flow measuring device. First, they must be located as close as possible. Although this is desired from the viewpoint of ease of manufacture and simplification of the structure,
The main reason is that accurate measurement cannot be performed unless the intake air temperature near the air flow rate detecting section is detected more than that.
However, in this case, if a temperature sensitive resistor is arranged upstream of the heating resistor, the flow of air will be disturbed downstream of the temperature sensing resistor. Is concerned. Conversely, if the temperature-sensitive resistor is arranged downstream of the heat-generating resistor, the heat generated by the heat-generating resistor warms the temperature-sensitive resistor, which causes a detection error of the intake air temperature. On the other hand, by arranging the heating resistor and the temperature-sensitive resistor at different levels, it is possible to solve both of the above problems.

However, a new problem in this case is that the distance from the wall of the passage differs between the heating resistor and the temperature-sensitive resistor, and the effect of heat from the wall is different between the two. That is. In other words, of the resistors arranged stepwise, those closer to the wall face are more likely to be affected by heat, and those farther than the wall face are less likely to be affected by heat. These thermal effects appear as changes in the wall temperature-temperature characteristics of the heating resistor type air flow measuring device as described later.

Regarding the improvement of the wall warmth characteristic, a supporting structure of a resistor disclosed in Japanese Patent Application Laid-Open No. 60-36916 is known as a disclosed technology. That is, the heating resistor and the temperature-sensitive resistor are arranged stepwise, and at the same time, a step is formed on the wall of the passage. As a result, the distance between the resistor and the passage wall surface can be adjusted longer, so that, for example, by increasing the amount of heat radiation from the support material, etc., it is less likely to be affected by heat from the wall surface. This is an improvement in the wall warmth characteristic of the present invention.

[0005]

However, there is still an unsolved problem in the low flow rate region in improving the wall warming characteristics of the prior art. This will be described in detail below. There are various phenomena in the temperature characteristics of the heating resistor type air flow measuring device. Above all, when a temperature difference occurs between the temperature of the intake air and the temperature of the wall surface of the intake pipe at the portion where the heating resistor serving as the detection sensor is disposed, a measurement error tends to occur. This is due to the operating principle of the heating resistor type air flow measuring device. Most heating resistor type air flow rate measuring devices use a heating circuit, which is a flow rate detecting unit, and a temperature sensing resistor, which detects intake air temperature, as sensing members.
And a drive circuit for driving them with a feedback circuit.

Here, the respective functions of the temperature-sensitive resistor and the heating resistor will be described below. First, the temperature-sensitive resistor compensates for the intake air temperature by measuring the resistance value at that temperature using the temperature coefficient of the resistor. That is, when the intake air temperature is low, the resistance value of the temperature-sensitive resistor decreases, and conversely, when the intake air temperature is high, the resistance value increases. The heating resistor is electrically connected to a bridge circuit together with the temperature-sensitive resistor to measure an air flow rate. In this method, a heating current Ih is supplied to the heating resistor by a feedback circuit so that a constant temperature difference (approximately 100 ° C. to 200 ° C.) is always maintained between the temperature sensing resistor and the heating resistor.

At this time (at high flow velocity), if the air flow rate is large, the heating resistor loses much heat to the air, so that a large heating current Ih is applied to maintain a constant temperature difference with the temperature sensing resistor. There must be. Conversely, when the air flow rate is small (at a low flow rate), the heating current Ih may be small because the heat generated by the heating resistor is small. That is, since the relationship between the air flow rate and the heating current Ih has a simple increasing relation, the heating current Ih can be used as an air flow rate signal. The heating resistor type air flow measuring device converts the heating current Ih into a voltage value or sometimes a frequency based on a pulse according to the market needs, and outputs it as an air flow signal.

Further, the wall temperature-temperature characteristic of the heating resistor type air flow measuring device will be described with reference to FIGS. FIG. 6 is an explanatory diagram when the wall temperature of the intake air passage and the intake air temperature of the heating resistor type air flow measuring device are the same. The operation of the heating resistor under the reference temperature condition is shown. In FIG. 6, the temperature-sensitive resistor 2 detects the intake air temperature Ta as described above, and supplies a heating current Ih to the heating resistor 1 by the drive circuit so as to have a constant temperature difference Th.
The temperature of the heating resistor 1 itself is Ta + Th. On the other hand, FIG. 7 is an explanatory diagram when the wall surface temperature of the intake air passage and the intake air temperature of the heating resistor type air flow measuring device are different. When the intake air temperature and wall temperature are different,
It is a figure explaining the principle of what is called a wall warmth characteristic, and shows operation of a heating resistor under the temperature condition (Tw> Ta temperature conditions) by which only the wall surface was heated. The intake air temperature Ta in FIG. 7 is the same as the intake air temperature Ta in FIG. 6, and the wall surface temperature of the air passage 4 is Tw.

First, between the temperature-sensitive resistor 2 and the wall of the passage,
Since it is electrically connected by a terminal or wiring for connecting to a drive circuit and is always supported by a support 3 or the like for mechanically holding the temperature-sensitive resistor 2, the wall of the air passage 4 is When a temperature difference occurs between the temperature-sensitive resistor 2 and the temperature-sensitive resistor 2, heat is always transferred between the wall surface portion and the temperature-sensitive resistor via the support 3.

In the case of FIG. 7, since the temperature is higher on the wall surface of the passage, heat is transferred from the passage wall surface toward the temperature-sensitive resistor 2 by q1. During the heat transfer, the heat of q2 is radiated to the airflow, but the heat quantity of q1-q2 moves toward the temperature-sensitive resistor 2.
For this reason, although the intake air temperature is originally Ta, the temperature of the temperature-sensitive resistor 2 is increased by ΔT due to q1-q2. The drive circuit supplies the heating current Ih + ΔIh so as to reach the above-mentioned constant temperature TH by the rise.
Therefore, the temperature of the heating resistor 1 itself is Ta + ΔT + TH
Since the heating current is increased by the amount of ΔT, the amount of ΔIh finally becomes a detection error of the heating resistor type air flow measuring device.

FIG. 8 is an explanatory diagram of the wall temperature-temperature characteristic of the heating resistor type air flow measuring device. 5 shows an example of experimental results of the wall warmth characteristics obtained by the inventors. The horizontal axis in FIG. 8 is the air flow rate, and the vertical axis is the percentage of the detected value when the wall temperature changes with respect to the measured value under the reference temperature condition. The reference temperature condition at the time of obtaining the measured value is Ta = Tw =
20 ° C., TH = 200 ° C. On the other hand, when the detected values were obtained, the temperature conditions were Ta = 20 ° C., Tw = 80 ° C., and T = 20 ° C.
H = 200 ° C. From FIG. 8, the measurement error received by q1-q2 is small in the high flow rate (high flow rate) region,
In the (low flow velocity) region, the error is large and increases to the plus side.

The reason for this is that in the high flow rate region, the amount of heat dissipated by q2 is dissipated with most of q1 being q2, so that little error occurs. On the other hand, in the low flow rate region, since the heat radiation of q2 is minute relative to q1, most of the amount of heat warms the temperature-sensitive resistor, resulting in a large measurement error. That is, the wall warmth characteristic is easily affected in the low flow rate region. In particular, since the flow rate at the time of idling becomes the lowest flow rate among the driving conditions of the automobile, the vehicle is easily affected in such a low flow rate range. As a result, the end user is perceived as a problem of deterioration of the stability of the engine idle, and the improvement is urgently required for the manufacturer of the heating resistor type air flow measuring device.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heating resistor type air flow measuring device in which measurement accuracy in a low flow rate region is improved.

[0014]

SUMMARY OF THE INVENTION The object of the present invention is to provide a first temperature-sensitive resistor supported by a support in an air passage and having a resistance value that changes according to the temperature of intake air, and a heat-dissipating device for the intake air. A heating circuit including a bridge circuit including a heating resistor for detecting a flow rate of the intake air based on the feedback signal; and a feedback circuit for controlling the heat dissipation of the heating resistor. In the measurement device, on the output side of the drive circuit, the second temperature-sensitive resistor is disposed in the air passage so that the first temperature-sensitive resistor receives the same thermal effect as the thermal effect received from the support or the like. And a correction circuit for correcting the air flow signal and outputting an output signal.

The correction circuit according to the present invention has a third temperature-sensitive resistor, and connects one end of the second temperature-sensitive resistor and one end of the third temperature-sensitive resistor in series. Then, the other end of the second temperature-sensitive resistor is connected to the output side of the drive circuit, and the other end of the third temperature-sensitive resistor is connected to the minus side of the drive circuit. The output signal is taken out from the connection portion at the end.

According to the present invention, the thermal effect of the first temperature-sensitive resistor is canceled by the second temperature-sensitive resistor, so that the measurement accuracy in the low flow rate region is improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking a heating resistor type air flow measuring device used in an internal combustion engine for a vehicle as an example. FIG.
1 is a diagram showing a circuit configuration of a heating resistor type air flow measuring device according to one embodiment of the present invention. The outline of the heating resistor type air flow measuring device of the present embodiment is shown from an electric circuit.
In the figure, the electric circuit of the heating resistor type air flow measuring device of the present embodiment includes a drive circuit 5 and a correction circuit 6. That is, the driving circuit 5 is roughly divided into a bridge circuit 7
And a feedback circuit 8. A heating resistor 1 (also indicated as RH) for measuring the intake air flow rate, and a temperature sensing resistor 2 (also indicated as a temperature sensing resistor RC) as a first temperature sensing resistor for compensating the intake air temperature. ),
The bridge circuit 5 is formed by the resistors R10 and R11. The feedback circuit 8 controls the heating resistor RH so as to maintain a constant temperature difference between the heating resistor RH and the temperature-sensitive resistor RC while applying feedback using the operational amplifier OP1.
Is a circuit for controlling the heat radiation of the heating resistor RH, and outputs an air flow signal V2 corresponding to the air flow by flowing the heating current Ih to the heating resistor RH.

The correction circuit 6 is composed of a temperature-sensitive resistor RC2 as a second temperature-sensitive resistor for temperature compensation and a temperature-sensitive resistor RC3 as a third temperature-sensitive resistor for voltage division. The voltage dividing circuit is connected to the output side of the driving circuit 5.
That is, the correction circuit 6 according to the present embodiment includes the temperature-sensitive resistor RC2
Is connected in series with one end of the temperature-sensitive resistor RC3, the other end of the temperature-sensitive resistor RC2 is connected to the output side of the drive circuit 5 that outputs the air flow signal V2, and This is a voltage dividing circuit in which the other end of the resistor RC3 is connected to the negative side of the drive circuit 5 and an output signal Vo is taken out from a connection at one end.

Next, a specific configuration example of the heating resistor type air flow measuring device of the present invention will be described. FIG. 2 shows a specific device configuration of the electric circuit of FIG. FIG.
FIG. 1 is a view showing a heating resistor type air flow measuring device according to an embodiment of the present invention. 2 shows a cross section of an air flow measuring device. In the figure, the heating resistor type air flow measuring device
Housing member 35 made of a molding material or the like, drive circuit 5
A circuit board 34 provided with a temperature sensitive resistor RC3 for dividing the output voltage, a heating resistor RH, a temperature sensitive resistor RC for intake air temperature compensation, a temperature sensitive resistor RC for temperature compensation, and a circuit board 34. And a supporting member made of a conductive member for electrically and mechanically connecting each of the resistors (RH, RC, RC2) and a housing member 35, and a sub air passage member provided with each resistor. 39, an integrated module 52 including components such as a control unit and a connector 36 for external interface.

The temperature-sensitive resistor RC and the temperature-sensitive resistor RC
2 has the same thermal effect (heat conduction) from the support body 3 supporting each resistor (RC, RC2) and the thermal effect (heat transfer) from the air flowing through the air passage 4 (including the auxiliary air passage 9). It is configured to be. For example, the temperature-sensitive resistor RC2 is disposed inside the same auxiliary air passage 9 (including the air passage 4) so that the temperature-sensitive resistor RC receives the same thermal effect as the thermal effect received from the support or the like. , And are supported by a support 3 of the same shape, the same size, and the same material. Further, the temperature-sensitive resistor RC2 is
It can be said that it is desirable to be disposed in the vicinity of the temperature-sensitive resistor RC from the viewpoint of equalizing the heat influence. In other words, the temperature-sensitive resistor RC2 is disposed inside the auxiliary air passage 9 (including the air passage 4) so that the temperature-sensitive resistor RC receives the same thermal influence as that of the support or the like. .

Further, the module 52 is fixed to the exclusive body 21 forming the air passage 4 through which the intake air 20 flows with a screw 37 while ensuring airtightness by a seal member 38. In the present embodiment, the dedicated body 21 forms a part of the intake pipe. However, for example, a part of an air cleaner or an existing intake duct may be used in place of the dedicated body 21. Further, the heating resistor type air flow measuring device may have a configuration including the dedicated body 21 and the like.

Next, the configuration and operation of the correction circuit 6 will be described. FIG. 3 is a diagram showing a correction circuit according to one embodiment of the present invention. The correction circuit 6 for dividing the air flow signal V2 using the temperature sensitive resistors RC2 and RC3 is shown. FIG.
In FIG. 3 and FIG. 3, the correction circuit 6 is a voltage dividing circuit composed of a temperature sensing resistor RC2 for temperature compensation and a temperature sensing resistor RC3 for voltage division, which are connected to the drive circuit 5.

That is, the correction circuit 6 is independent of the temperature-sensitive resistor RC for compensating the intake air temperature, and is independent of the driving of the drive circuit 5 and cancels the temperature characteristics. Is disposed in the air passage. This resistance value changes when the temperature-sensitive resistor RC2 receives heat from the passage wall surface or the like, but is canceled by changing the output value from the heating resistor-type air flow measurement device. As described above, the correction circuit 6 corrects the partial pressure of the air flow rate signal V2 and outputs the output signal Vo. Hereinafter, the correction of the correction circuit 6 of the present embodiment will be described in detail.

On the output side of the drive circuit 5 to which the measured air flow rate signal V2 is output, RC3 disposed on the circuit board 34 and RC2 disposed in the air passage are connected in series. . Here, assuming that the output from the point M as a connection part between RC2 and RC3 is Vo, Vo = V2 × RC3 / (RC2 + RC3) (Equation 1), and Vo is a voltage division of V2 by the resistance ratio of RC2 and RC3. Is determined. Then, the temperature change of V2 and RC2 and R
Considering the temperature change of the resistance value of C3, Vo can be made independent of the temperature change.

If the above idea is shown by a concrete example, first, when the denominator / numerator on the right side of the above equation (1) is divided by RC3, Vo = V2 / ((RC2 / RC3) +1) (2) ). Next, when RC2≫RC3, RC2 /
RC3≫1 and (RC2 / RC3) + 1 ≒ RC2 / RC3 (Equation 3). By substituting Equation (3) into Equation (2), Vo ≒ V2 × RC3 / RC2 (Equation 4) Vo becomes , (Equation 4).

On the other hand, the resistance value of each temperature sensitive resistor with respect to the temperature becomes a value proportional to each temperature coefficient α, and the resistance value R _{T at} T ° C. is: R _T = R ₀ × (1 + αT) (Equation 5) ) R ₀ : resistance value at 0 ° C. Further, the output value of V2 is a value that is approximately proportional to the resistance value of RC from FIG. 1, so that the relationship of Expression (6) holds. V2∝RC _T = RC ₀ × (1 + α1 × T) (Equation 6) RC ₀ : resistance value of RC at 0 ° C. α1: temperature coefficient of RC.

[0027] Thus, equation (4) and (6) below relationship, Vo = V2 × RC3 / RC2 = K × RC 0 (1 + α1T) × RC3 0 × (1 + α3T) / RC2 0 (1 + α2T) ( Equation 7 ) K: Coefficient RC2 ₀ : Resistance value of RC2 at 0 ° C. RC3 ₀ : Resistance value of RC3 at 0 ° C. α2: Temperature coefficient of RC2 α3: Temperature coefficient of RC3

Here, for example, the temperature coefficients α1 and α2 of RC and RC2 are set to α1 = α2, and the thermal effects on RC and RC2 are almost equal (the same as described above so that T becomes equal). (1 + α1T) = (1 + α2T) (Equation 2) If the temperature coefficient α3 of RC3 is set to be extremely small in relation of α3≪1 (minimum than 1), _{8) RC3T = RC3 0 × (} 1 + α3T) = RC3 0 ( number 9), and from equation (7), i.e., it is possible to remove the influence caused by temperature from Vo.

In other words, the correction circuit 6 generates (RC2, RC
(3) is transmitted to the temperature-sensitive resistor RC via the support 3 (q
1-q2) cancels the thermal effect (ΔT). Note that the temperature-sensitive resistor RC3 as the third temperature-sensitive resistor may be a general resistor as long as the temperature coefficient α3 of RC3 is minimal, that is, as long as the temperature dependency is small. Yes. The temperature-sensitive resistor referred to in this specification is understood as a resistor in a broad sense. FIG. 4 is a diagram showing the wall temperature-temperature characteristic of the heating resistor type air flow measuring device of the present embodiment. That is, as shown in FIG.
(q1−q2), the detection error Δ that changes depending on the level of the flow rate
T is given a correction value obtained by a correction circuit composed of RC2 and RC3, and is canceled to improve the wall temperature characteristic.

In addition to the above-described embodiment, a method using the temperature coefficients of the RC2 and RC3 resistors may be used. For example, a member forming the two resistors (printing when the resistors are performed by printing or the like) may be used. The same effect can be obtained by changing the thermal conductivity of the plate-like member to be formed. As still another method, a temperature-sensitive resistor RC for intake air temperature compensation is used.
The temperature-sensitive resistor RC2 for temperature compensation has the same support structure as that of the temperature-sensitive resistor RC2. Further, the temperature-sensitive resistor R
The temperature coefficient of C2 is determined by the circuit board 34 constituting the drive circuit 5.
It is also conceivable to select a resistor whose value is larger than the temperature coefficient of the partial pressure sensing resistor RC3 arranged above.

That is, the circuit board 34 constituting the drive circuit 5
Are disposed near the passage wall surface. By arranging, R
The resistors C2 and RC3 are heated under substantially the same temperature conditions. Since the resistance value of RC2 has the same support structure as that of the temperature-sensitive resistor RC, the resistance value change is small in a high flow rate region and is large in a low flow rate region by being exposed to intake air. Become. On the contrary,
Since the temperature-sensitive resistor RC3 is not exposed to the intake air, the amount of change in the resistance value of the temperature-sensitive resistor RC3 is constant irrespective of the flow rate. Since it is small, the change in the resistance value is small. This is illustrated in FIG.

FIG. 5 is a diagram showing an air flow rate and a resistance change rate of RC2 and RC3 in another embodiment according to the present invention. As described above, the output voltage corresponding to the intake air flow rate of the heating resistor type air flow rate measuring device is Vo = V2 × RC3 / (RC
2 + RC3). For this reason, in the high flow rate region, since the change in the resistance value is small, RC3 / (RC
2 + RC3) ≒ 1, and the value of Vo shows almost the same value as the output value at normal temperature. That is, it can be said that it does not depend on the temperature change. Then, in a low flow rate region, the resistance value of RC2 becomes large.
3 / (RC2 + RC3) ≪1, and the value of Vo decreases. That is, similarly to the above, the wall temperature / temperature characteristic of the heating resistor type air flow rate measuring device is corrected.

In summary, the heating resistor type air flow measuring device according to the present invention is used in an internal combustion engine and has a first temperature-sensitive resistor whose resistance value changes in accordance with the temperature of the intake air. A heating resistor for detecting an air flow rate based on a heat radiation amount of the heating resistor, and further electrically connecting the heating resistor to the first temperature-sensitive resistor to control a heating temperature of the heating resistor. Wherein the second and third temperature-sensitive resistors are arranged separately from the first temperature-sensitive resistor, and the resistance ratio of the second and third temperature-sensitive resistors varies with the ambient temperature. To offset the measurement error of the heating resistor type air flow measurement device due to the change of the intake air temperature or the measurement error of the heating resistor type air flow measurement device due to the difference between the intake air temperature and the temperature of the circuit arrangement part. It is characterized by the following.

The resistor element according to the embodiment of the present invention used in the heating resistor type air flow measuring device shown in FIG. 2 has three individual resistors (RH, RH) arranged in the sub air passage. RC, RC2) and the individual support members 3 are separately configured, so that there is a problem that the structure is complicated. A description will be given of a solution to this difficulty. FIG.
FIG. 6 is a view showing a resistor element according to another embodiment of the present invention. The resistor element of the present embodiment shown in FIG.
It has a structure in which three resistors are integrated for simplification. For example, three resistors (RH, RC, RC2) are
Together with the electrodes 41 and the conductors 42, they are formed on a ceramic thin plate as a single plate-like element member 40. That is, at least the temperature-sensitive resistor RC2 among the resistors
If the configuration is such that the temperature-sensitive resistors RC are arranged on the same member on which the temperature-sensitive resistors RC are formed, it is possible to reduce the complexity of the structure (increase in the manufacturing cost of the three resistors) and to reduce the heat transfer and heat transfer conditions. Are easily equalized, and there is an advantage that the thermal effects on the respective resistors are equalized.

Next, an embodiment in which the heating resistance type air flow rate measuring device of the above-described embodiment is applied to an electronic fuel injection type internal combustion engine will be described. FIG. 10 is a diagram showing a fuel injection control system for an internal combustion engine according to one embodiment of the present invention.
The configuration and operation of the fuel injection control system for an internal combustion engine according to the present embodiment are as follows. The intake air 67 sucked from the air cleaner 54 is supplied to the body 53 of the heating resistance type air flow measuring device, the suction duct 55, and the throttle body 5.
8 and an intake manifold 59 provided with an injector 60 to which fuel is supplied, and is sucked into the engine cylinder 62. At this time, the flow rate of the intake air 67 in the low flow rate range is accurately measured by the heating resistance type air flow rate measuring device according to the present invention. On the other hand, gas 63 generated in the engine cylinder 62 is discharged through an exhaust manifold 64.

An output signal output from a module 52 serving as a heating resistance type air flow measuring device, a throttle valve angle signal output from a throttle angle sensor 57, and an oxygen concentration meter 65 provided in an exhaust manifold 64
The control unit 66, which has input the oxygen concentration signal output from the engine and the engine speed signal output from the tachometer 61, sequentially calculates these signals to obtain the optimum fuel injection amount and idle air control valve opening. The degree is obtained, and the injector 60 and the idle control valve 66 are appropriately controlled using the value.

As described above, in the fuel injection control system of the internal combustion engine that executes the fuel injection control using the corrected output signal from the heating resistance type air flow measuring device according to the present invention, the heating resistance type is controlled in the low flow rate region. Since the measurement accuracy of the air flow measurement device is improved, for example, warm up the engine in the garage with the shutter closed in the winter morning, open the shutter after the internal combustion engine has sufficiently warmed up, and go out of the garage. This leads to an improvement in the stability of the internal combustion engine at the time of idling, for example.

[0038]

According to the present invention, the measurement error due to the external temperature, particularly the so-called wall temperature-temperature characteristic caused by the thermal influence from the intake pipe wall surface, is improved, and the measurement accuracy of the heating resistor type air flow measuring device is improved. This has the effect of improving the performance.

The present invention is also effective in improving the stability of the low-temperature idle characteristic of the internal combustion engine using the fuel injection control system.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a heating resistor type air flow measuring device according to one embodiment of the present invention.

FIG. 2 is a view showing a heating resistor type air flow measuring device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a correction circuit according to an embodiment of the present invention.

FIG. 4 is a view showing a wall temperature-temperature characteristic of the heating resistor type air flow measuring device of the present embodiment.

FIG. 5 is a diagram showing an air flow rate and a resistance change rate of RC2 and RC3 in another embodiment according to the present invention.

FIG. 6 is an explanatory diagram when the wall temperature of the intake air passage and the intake air temperature of the heating resistor type air flow measuring device are the same.

FIG. 7 is an explanatory diagram when the wall surface temperature of the intake air passage and the intake air temperature of the heating resistor type air flow measuring device are different.

FIG. 8 is an explanatory diagram of a wall temperature-temperature characteristic of the heating resistor type air flow measuring device.

FIG. 9 is a view showing a resistor element according to another embodiment of the present invention.

FIG. 10 is a diagram showing a fuel injection control system for an internal combustion engine according to one embodiment of the present invention.

[Explanation of symbols]

1, RH: heating resistor, 2, RC: temperature-sensitive resistor, 3: support, 4: air passage, 5: drive circuit, 6: correction circuit, 7
... bridge circuit, 8 ... feedback circuit, 9 ... auxiliary air passage, 20 ... intake air, 21 ... dedicated body, 34 ... circuit board, 35 ... housing member, 36 ... connector, 37 ...
Screw 38, sealing material 39, auxiliary air passage member 40
Element member, 41: Electrode, 42: Conductor, 52: Module, 53: Body, 54: Air cleaner, 55: Suction duct 56: Idle air control valve, 57: Throttle angle sensor, 58: Throttle body, 59: Intake manifold, Reference Signs List 60 injector, 61 tachometer, 62 engine cylinder, 63 gas, 64 exhaust manifold, 65 oxygen meter, 66 control unit, 67 intake air, R10, R11 resistance, O
P1 ... Op amp

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinya Igarashi 2477 Takaba, Hitachinaka-shi, Ibaraki Prefecture Within Hitachi Car Engineering Co., Ltd.

Claims (6)

[Claims] A first temperature-sensitive resistor supported by a support in an air passage and having a resistance value that changes according to a temperature of the intake air; and a flow rate of the intake air based on heat radiation to the intake air. A heating circuit comprising a bridge circuit including a heating resistor to be detected and a feedback circuit for controlling the heat dissipation of the heating resistor, wherein the heating resistor type air flow measuring device outputs an air flow signal; On the output side, a second temperature-sensitive resistor disposed in the air passage so that the first temperature-sensitive resistor is subjected to the same thermal influence as that received from the support or the like, A heating resistor type air flow measuring device, further comprising a correction circuit for correcting the air flow signal and outputting an output signal. 2. The device according to claim 1, wherein the correction circuit has a third temperature-sensitive resistor, and connects one end of the second temperature-sensitive resistor with one end of the third temperature-sensitive resistor. Connected in series, the other end of the second temperature sensitive resistor is connected to the output side of the drive circuit, the other end of the third temperature sensitive resistor is connected to the minus side of the drive circuit, A heating resistor type air flow measuring device, wherein the output signal is taken out from a connection portion at each of the one ends. 3. The temperature sensing device according to claim 2, wherein the first and second temperature sensing resistors have the same temperature coefficient, and the third temperature sensing resistor has a temperature coefficient smaller than one. A heating resistor type air flow measuring device, comprising: 4. A heating resistor type air flow measuring device according to claim 2, wherein said second temperature sensing resistor is disposed near said first temperature sensing resistor. 5. The airflow measurement device according to claim 2, wherein said second temperature-sensitive resistor is disposed on the same member on which said first temperature-sensitive resistor is formed. apparatus. 6. A fuel injection for an internal combustion engine, wherein fuel injection control is executed by using an output signal from the heating resistor type air flow measuring device according to any one of claims 1 to 5. Control system.