JP2730760B2 - Engine intake air amount detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a device for detecting an intake air amount of an engine, and particularly to a measure for improving the detection accuracy.

(Prior Art) Conventionally, as an engine control device, for example,
As disclosed in JP-A-157245, in an engine provided with a fuel injection injector in an intake passage, a hot-wire type intake flow rate sensor is provided in the intake passage, and a rotation speed sensor for detecting a rotation speed of the engine is provided. There is known an apparatus in which the amount of fuel injected from the injector is controlled based on the output of each sensor.

In the device having the intake flow rate sensor as described above, for example, when a pulsation of the intake flow occurs when the throttle valve is fully opened, the sensor directly picks up the pulsation, and the fuel injection amount is set accordingly. More fuel is injected from the injector than the fuel amount corresponding to the amount of intake air actually sucked into the cylinder, and the air-fuel ratio becomes over-rich. Therefore, in the above-mentioned publication, the output signal of the intake flow rate sensor is integrated and calculated, and the integrated value is output as an air amount value, so that the influence of the pulsation of the intake flow is reduced, and the intake air amount and the engine The engine operating state is detected using the rotation speed as a parameter, and when the engine is in the operating region where pulsation of the intake air flow is likely to occur, the fuel injection amount is reduced and corrected, and the detection of excess intake air by the sensor is corrected, and the air-fuel ratio is adjusted to an appropriate value. We are taking measures to maintain it.

(Problems to be Solved by the Invention) Incidentally, the intake air flow sensor generally outputs a signal corresponding to the intake air amount of the engine. This signal corresponds to the charging efficiency, i.e. the ratio of the mass of the actual intake air to the mass of the intake air that can be taken by the engine under normal conditions. Therefore, when the correction of the excessive intake air amount detection by the sensor is performed as described above, the atmospheric condition (atmospheric pressure, intake air temperature) changes because an operation region in which the pulsation of the intake air flow easily occurs is fixedly provided. With the correction using the intake air amount and the engine speed based on the sensor output as parameters, accurate correction cannot be performed.

The present invention has been made in view of such a point, and an object of the present invention is to accurately obtain information on an intake air flow rate from an output signal of an intake air flow rate sensor, and to correct excessive air intake amount detection by the sensor. Is performed with high accuracy.

(Means for Solving the Problems) In order to achieve the above object, a solution of the invention according to claim 1 includes a detecting means for outputting a signal corresponding to an intake air amount of an engine, and an output from the detecting means, A volume efficiency calculating means for calculating the volume efficiency of the intake air amount from the signal, and receiving an output of the volume efficiency calculating means, and in a high load region, increasing the intake air amount by the detecting means based on the volume efficiency of the intake air amount to a high load. Correction means for correcting the decrease as much as possible is provided. Here, the volumetric efficiency refers to the ratio of the actual volume of intake air to the volume of intake air that can be taken by the engine.

As a specific example of the detection means, in the invention of claim 2, a hot wire type which outputs a signal corresponding to the charging efficiency is used. In the invention of claim 3, it is assumed that the volumetric efficiency of the intake air amount obtained by the volumetric efficiency calculating means in claim 1 has been smoothed.

(Operation) With the above configuration, in the inventions according to the first to third aspects, in the high load area, the correction means corrects the intake air amount to be reduced as the load increases, so that the sensor detects the excessive intake air amount. Is corrected.

In this case, the volume efficiency of the intake air amount is obtained by the volume efficiency calculation means, and the correction is performed based on the volume efficiency. Therefore, the correction of the excessive detection of the intake air amount by the sensor is accurately performed regardless of the fluctuation of the atmospheric condition. . In particular, according to the third aspect of the invention, the delay due to the intake system capacity can be dealt with by the smoothing processing of the volumetric efficiency of the intake air amount.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an engine provided with an intake air amount detecting device according to an embodiment of the present invention. In the figure, 1 is an engine,
Reference numeral 2 denotes a cylinder formed in the engine 1 and reference numeral 3 denotes a piston slidably fitted in the cylinder 2, and a combustion chamber 4 is formed by the cylinder 2 and the piston 3.

An intake passage 6 is connected to the combustion chamber 4, and the intake passage 6 supplies intake air to the combustion chamber 4. The intake passage 6
An intake valve 7 is provided at the opening on the combustion chamber 4 side. The intake passage 6 is provided with a throttle valve 8 for adjusting the amount of intake air. Further, an injector 9 for injecting fuel into the intake air is provided near the combustion chamber 4 in the intake passage 6.

An exhaust passage 11 is connected to the combustion chamber 4, and exhaust gas is exhausted from the combustion chamber 4 through the exhaust passage 11.
An exhaust valve 12 is provided at an opening of the exhaust passage 11 on the combustion chamber 4 side. The exhaust passage 12 is provided with a catalyst 13 for purifying exhaust gas. Further, 14 is a spark plug provided in the combustion chamber 4, 15 is a distributor, and 16 is an ignition coil. The injector 9 is controlled by the control unit 20.

Further, a known hot-wire type air flow sensor 21 is provided in the intake passage 6. The hot-wire type air flow sensor 21 is of a type called a hot wire, but there is also a type called a hot film, for example. The air flow sensor 21 outputs a signal corresponding to the amount of intake air of the engine, and functions as a hot-wire detection unit. The distributor 15 is provided with a crank angle sensor 22 for detecting a crank angle. Further, 23 is an intake air temperature sensor for detecting the intake air temperature, and 24 is an atmospheric pressure sensor for detecting the atmospheric pressure. The output signals of these sensors 21 to 24 are input to the control unit 20.

Next, the operation control of the control unit 20 is performed in the second
Description will be made based on the block diagram of FIG. In the drawing, first to calculate the air density ρ based on the intake air temperature Tair and atmospheric pressure Patp in block B _1. On the other hand, determine the volumetric efficiency of the intake air amount passing through the air flow sensor 21 in block B _2. That is, the output Q (corresponding to the mass flow rate) of the air flow sensor 21, the engine speed N, the atmospheric density ρ, and the constant Ksa are calculated based on the following equation: Veo = Ksa · (Q / N) · (1 / ρ) Ask for. Here, Q / N represents the filling efficiency.

Next, equation volumetric efficiency Vecca in the cylinder by "smoothing process" in block _{B 3, Vecca (i) =} Kcca × Vecca (i-1) + (1-Kcca) ×
Asked by Veo. Here, Kcca is a first-order lag constant (0 ≦ Kc
ca <1), (i-1) indicate the previous value, and (i) indicates the current value. This “smoothing process” is a process for coping with a delay due to the intake system capacity from the throttle valve 8 to the intake valve 7.

Further corrects the intake air amount excessive detected by the sensor in block B _4. That is, the engine speed in block B ₅ N
Then, the correction value Cve is indexed from the map based on the volume efficiency Vecca in the cylinder. As shown in FIG. 3, the correction value Cve decreases as the volume efficiency Vecca increases in a region where the volume efficiency Vecca in the cylinder is large. Then, a "Cve · Vecca" in block B _4, which is the predicted true value Ve of the volumetric efficiency. As a result, as shown in FIG.
The intake air amount detected by the air flow sensor 21 is corrected so as to decrease as the load becomes higher, and the excess intake air amount detected by the air flow sensor 21 is corrected. In that case, the volumetric efficiency of the intake air volume Ve
Since cca is obtained and the correction is performed based on this volume efficiency Vecca, the correction of the excessive intake air amount detection by the airflow sensor 21 is accurately performed regardless of the fluctuation of the atmospheric condition.

Next, the density correction by multiplying the air density ρ to predict the true value Ve of the volumetric efficiency at block B _6, the charging efficiency of the volumetric efficiency Ve
Replace with Ce. Moreover, to calculate the basic pulse width Tp = Ce · K _F and a charging efficiency Ce and the coefficient K _F in block B _7. The CPU 1 calculates an invalid pulse width T _V in block B _8, obtains a final pulse width Ti by the sum of the invalid pulse T _V and the basic pulse width Tp, the fuel is injected on the basis of the last pulse width.

Next, the operation control of the control unit 20 is performed in the fifth mode.
A description will be given based on the flowchart of FIG. After the start, first, reads the output Q of the air flow sensor 21 in step S _1, reads the engine speed N in Step S _2, reads the air density ρ in step S _3. Then, a volumetric efficiency Veo amount of intake air passing through the air flow sensor 21 in step S _4,
Calculated volumetric efficiency Vecca in the cylinder by "smoothing process" in the step S _5, and the index correction value Cve in step S _6, the correction of the intake air amount excessive detected by the sensor in step S _7. Then replace the charging efficiency Ce predicted true value Ve of the volumetric efficiency at step S _8, calculates the basic pulse width Tp at step S _9, obtains a final pulse width Ti in step S _10, step S ₁₁
Then, fuel injection is performed with the final pulse width Ti, and the routine returns.

In the above flow, the steps S ₄ and S _5,
A volume efficiency calculating means 31 receives the output of the detection means (air flow sensor) 21 and calculates the volume efficiency of the intake air amount from the signal. Further, in step S ₆ and S _7, receives the output of the volumetric efficiency calculating means 31, in the high load region, as will high-load intake air amount by the detection means (airflow sensor) 21 based on the volumetric efficiency of the intake air amount The correction means 32 for performing the reduction correction is configured.

Therefore, in the above embodiment, in the high load region, the intake air amount detected by the air flow sensor 21 is corrected to decrease as the load increases, and the air flow sensor
Since the excessive intake air amount detection by 21 is corrected, the influence of the pulsation of the intake air flow and the backflow of the intake air (backflow of the intake air from the cylinder) can be reduced, and the air-fuel ratio can be maintained at an appropriate value.

In this case, the volumetric efficiency Vecca of the intake air amount is obtained from the output signal Q of the airflow sensor 21, and correction is performed based on the volumetric efficiency Vecca. Correction is performed with high accuracy.

(Effects of the Invention) As described above, according to the intake air amount detection device for an engine according to the first to third aspects of the present invention, the volumetric efficiency of the intake air amount is obtained from the signal corresponding to the intake air amount obtained by the detection means. In the high-load region, based on the volumetric efficiency, the amount of intake air detected by the detection means is corrected to decrease as the load increases, so that the correction of the excessive detection of the intake air amount by the sensor can be accurately performed regardless of changes in atmospheric conditions. Can do well.

[Brief description of the drawings]

The drawings illustrate an embodiment of the present invention. FIG. 1 is an overall schematic configuration diagram, FIG. 2 is a block diagram showing control of a control unit, and FIG. 3 shows a correction value Cve for a volumetric efficiency Vecca of an intake air amount. FIG. 4 is a characteristic diagram, FIG. 4 is a diagram showing the volumetric efficiencies Ve, Vecca of the intake air amount with respect to the throttle valve opening, and FIG. 5 is a flowchart showing the control of the control unit. DESCRIPTION OF SYMBOLS 1 ... Engine 21 ... Hot wire type air flow sensor (detection means) 31 ... Volume efficiency calculation means 32 ... Correction means

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshihide Nishikawa 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-60-195353 (JP, A) JP-A-62 JP-A-113842 (JP, A) JP-A-63-16157 (JP, A) JP-A-58-15740 (JP, A) JP-A-63-266153 (JP, A) JP-A-61-152935 (JP, A) )

Claims (3)

(57) [Claims] A detecting means for outputting a signal corresponding to an intake air amount of an engine; a volume efficiency calculating means for receiving an output of the detecting means and calculating a volume efficiency of the intake air amount from the signal;
Correction means for receiving the output of the volumetric efficiency calculating means, and in the high load region, correcting the intake air amount by the detecting means based on the volumetric efficiency of the intake air amount so as to decrease as the load increases. Intake air amount detection device. 2. An intake air amount detecting device for an engine according to claim 1, wherein said detecting means is of a hot wire type which outputs a signal corresponding to charging efficiency. 3. The volumetric efficiency of the intake air amount obtained by the volumetric efficiency calculating means has been subjected to a smoothing process.
An intake air amount detection device for an engine as described in the above.