JP2867433B2 - Apparatus for measuring intake air amount of internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in an intake air amount measuring device for an internal combustion engine.

(Prior Art) An internal combustion engine provided with two turbochargers in parallel in an intake passage in order to eliminate a supercharging delay during transient operation of the engine is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-65022. I have.

In this case, by measuring the intake air amount necessary to calculate the fuel injection amount to the engine by summing the outputs of the intake air amount sensors provided upstream of each turbocharger, from idle to maximum output Some are designed to measure the amount of intake air with high accuracy.

(Problems to be Solved by the Invention) However, when two intake air amount sensors are installed as described above, if one of the sensors fails, the measurement of the intake air amount is hindered, and accurate control of the fuel injection amount is difficult. It becomes impossible and the operability of the engine deteriorates.

An object of the present invention is to solve such a problem.

(Means for Solving the Problems) In the present invention, as shown in FIG. 1, intake air amount sensors 10 and 11 are interposed in each of two branched intake passages.
The intake passages are joined at the downstream side of the intake air amount sensors 10 and 11 and connected to the internal combustion engine.
The means 50 for detecting an abnormality of 0 and 11 and the output of both sensors 10 and 11 are added together when there is no abnormality. Calculation means 51 for obtaining the intake air amount of the engine by doubling.

(Operation) In the above configuration, all intake air is sucked into the internal combustion engine as a total amount from each intake passage. Therefore, even if an abnormality such as a failure occurs in one of the intake air amount sensors 10 and 11, it is possible to accurately detect the total intake air amount of the engine by doubling the output of the other normal sensor. It is possible.

In addition, in an internal combustion engine, the flow rate of intake air at the time of maximum output generally becomes very large, so that the flow rate variation from the maximum intake air amount to the minimum intake air amount at idling is very wide. On the other hand, according to the above configuration, the intake flow rate of the entire engine is equally divided and detected by the two intake flow rate sensors 10 and 11, so that the maximum flow rate to be individually detected becomes smaller accordingly. The detection accuracy at the time of a small flow rate such as at the time of idling is improved.

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

FIG. 2 shows an overall schematic configuration of the present invention, and FIG. 3 shows an actual arrangement relationship in an engine room of an automobile.

The engine 1 is provided with two turbochargers 2, 3, which are equipped with exhaust turbines 2a,
3a and the intake compressors 2b and 3b are arranged coaxially. One of the turbochargers 2 is disposed on the exhaust manifold 4 of the cylinders # 1 to # 3, and the other is disposed on the exhaust manifold 4 of the cylinders # 1 to # 3.
It is attached to the exhaust manifold 5 of each of the four to # 6 cylinders, and is driven by the exhaust of each of the three cylinders.

The exhaust passages 6a and 6b on the downstream side of the respective exhaust turbines 2a and 3a merge into one exhaust passage 6, where the exhaust catalytic converter 7
And a muffler 8 are installed.

A pair of intake air sensors, such as, for example, hot wire flow meters,
10, 11 are installed.

The outlet side of each of the intake air amount sensors 10 and 11 is connected to the inlet side of each of the intake compressors 2b and 3b of the turbochargers 2 and 3 via intake passages 12a and 12b, respectively.

The outlet sides of the intake compressors 2b and 3b are located at the intake passages 13a and 13b.
And connected to each cylinder of the engine 1 via the intake collector 15.

Therefore, from the air cleaner 9, each intake air sensor 10,
The intake air diverted to 11 and flowing to the intake compressors 2b and 3b is joined by an intercooler 14 and then distributed to each cylinder of the engine 1 via an intake collector 15.

Between the intake collector 15 and the cylinder head 16, a throttle chamber 18 containing a six-unit throttle valve 17 is provided.
Is interposed.

Each of the intake compressors 2b, 3b and intake air amount sensors 10, 11
The intake passages 12a and 12b between them are connected via a communication passage 19 in order to reduce mutual intake pulsation and increase the intake air amount measurement accuracy.

20 is the intake compressor 2b at the time of engine deceleration,
In order to prevent surging of 3b, the intercooler 14
A return passage connecting between the downstream communication passage 19 and a communication passage 19, a pair of diaphragm type control valves 21 and 21 are interposed in the return passage 20, and a negative pressure downstream of the throttle valve 17 is supplied to an auxiliary air passage. When the negative pressure is increased to a predetermined value or more during deceleration, the control valves 21 and 21 are opened to short-circuit the upstream and downstream of the intake compressors 2b and 3b, thereby preventing surging. Reference numeral 24 denotes an air regulator for introducing auxiliary air downstream of the throttle valve 17 in accordance with the engine cooling water temperature, and reference numeral 25 denotes an auxiliary air control valve for introducing auxiliary air for idle speed control.

By providing the two intake air amount sensors 10 and 11 in this way, the shared flow rate of each sensor 10 and 11 is reduced to half of the total, so that highly accurate flow rate measurement from idling to maximum output is possible. However, based on the outputs of the sensors 10 and 11, a control circuit 30 including a microcomputer as shown in FIG. 4 calculates the intake air amount.

The microcomputer is an input / output interface I /
O, central processing unit CPU, storage device ROM, RAM, etc.

Then, the fuel injection amount is determined so as to obtain a predetermined air-fuel ratio corresponding to the intake air amount, and an injection pulse signal is output to the fuel injection injector 26 in synchronization with the output of the crank angle sensor 27.

The calculation of the intake air amount for determining the fuel injection amount is performed as shown in the flowchart of FIG.

First, the intake air amount signal Q1 from the first intake air amount sensor and the intake air amount signal Q2 from the second intake air amount sensor are read (steps 1 and 2). The values are compared with each other to determine whether each signal is abnormal (steps 3 and 4). If the output of each sensor is smaller than the predetermined minimum value while the engine is rotating, it is determined that an abnormality has occurred.

When neither is abnormal, the intake air amount Q of the engine is Q =
Q1 + Q2 is obtained (step 5), and the fuel injection amount Tp is calculated based on this (step 10). Note that the fuel injection amount is obtained as Tp = K × Q / N (where K: constant, N:
Rotation speed).

On the other hand, when an abnormality occurs in one of the two intake air amount sensors, for example, the second intake air amount sensor, in step 6, the engine intake air amount is set to Q = 2 × Q1, and The intake air amount Q is obtained by doubling the sensor output of the above.

Similarly, when the first intake air amount sensor is abnormal, the normal second intake air amount sensor output Q2 is doubled, and the engine intake air amount Q
(Steps 7 and 8).

The intake air flowing through each intake air sensor is 1/2 of the engine intake air
Therefore, the total flow rate can be estimated from either one of the sensor outputs.

In this way, even if an abnormality occurs in either one, the intake air amount is calculated based on the remaining normal sensor output, so that the engine intake air amount is accurately obtained, and based on this, an accurate fuel injection is performed. Volume control can be maintained.

When both the first and second intake air amount sensors are abnormal, the intake air amount Q is calculated based on the throttle opening and the rotation speed (step 9). In this case, however, it is inevitable that the measurement accuracy of the intake air amount is reduced as compared with the above. Therefore, when it is determined that an abnormality has occurred in both of them, it is preferable to display a warning so as to immediately notify the driver.

Further, since the total amount of the engine intake air is measured by being divided into two parts by the two sensors 10 and 11, the dynamic range of each sensor can be made smaller, and as a result, a small flow rate such as in idle operation can be obtained. Since the measurement accuracy at the time can be improved, highly accurate fuel injection control can be performed from the time of full opening to the time of idling.

(Effects of the Invention) As described above, according to the present invention, when an abnormality such as a failure occurs in one of the two intake air amount sensors, the output of the other normal sensor is doubled, so that the total intake air of the internal combustion engine is obtained. Because the amount is obtained, even if the sensor is abnormal, it is possible to measure the intake air amount with high accuracy that is almost the same as when the sensor is normal.
By calculating the fuel injection amount based on this, it is possible to prevent the drivability from deteriorating.

Also, the total intake air amount of the engine is 2 by two intake air amount sensors.
Since the measurement is performed in a divided manner, it is possible to further increase the measurement accuracy in a small flow rate region such as at the time of idling, and to further improve the accuracy of the fuel injection control.

[Brief description of the drawings]

1 is a diagram corresponding to claims showing the configuration of the present invention, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 3 is a plan view showing the same arrangement in an engine room, and FIG. FIG. 5 is a flowchart showing the control operation. 10, 11… intake air amount sensor, 12a, 12b… intake air passage, 15…
Intake collector, 30 Control circuit.

Claims (1)

(57) [Claims] An intake air sensor is interposed in each of the two branched intake passages, and the intake passages are joined at a downstream side of the intake air amount sensor to be connected to an internal combustion engine. The means for detecting an abnormality and the sum of the outputs of both sensors when there is no abnormality, and doubling the output of the other normal intake air amount sensor when detecting one abnormality, An intake air amount measuring device for an internal combustion engine, comprising: an arithmetic unit for calculating an amount.