JPS5914168B2 - Internal combustion engine intake air flow rate detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake air flow rate detection device for an internal combustion engine that utilizes Karman vortices.

The fuel injection system of an internal combustion engine requires momentary measurement of the amount of intake air.

In addition, so-called vortex flowmeters, which measure fluid flow rate by arranging a vortex generation column in the intake air passage and measuring the Karman vortices generated downstream of the vortex generation column, have excellent vibration resistance because they have no moving parts. It can be said that this flowmeter is suitable for mobile internal combustion engines, especially automobiles. However, since the intake air of an internal combustion engine does not flow uniformly but pulsates, if a vortex generating column is provided, stable and uniform vortices will not be generated. Particularly, when the manifold negative pressure near the fully open throttle valve is small, about 50 mmH9 or less, the number of vortices generated by this intense pulsation becomes irregular, making it unreliable as a flowmeter. This pulsation of the intake air is caused by the overlapping operation of each intake valve, especially in a multi-cylinder engine, and a negative pressure surge pulse occurs at the moment the intake valve opens.

When the head nottle valve is closed, the negative pressure surge pulse is sufficiently attenuated upstream due to the orifice effect of the throttle valve, so the vortices of the vortex 15 flowmeter are generated in unison and the flowmeter operates normally. It performs its functions, but
When the throttle valve is fully open, it is not sufficiently damped even on the upstream side of the throttle valve, which blocks the flow of intake air and generates vortices irregularly, making it unreliable as a flowmeter.
20 In view of the above-mentioned circumstances, this invention suppresses the pulsation of the airflow passing through the vortex generating column and generates a stable vortex even when the throttle valve is fully open, thereby achieving stable flow rate detection over the entire operating range. It attempts to make it possible.

Hereinafter, 25 embodiments of the present invention shown in the figures will be described.
That is, first, in FIG. 1, reference numeral 1 denotes an intake air conduit that guides intake air to an internal combustion engine (not shown), and a notch valve 2 for controlling the amount of air intake is provided in the middle of the conduit.

Reference numeral 3 denotes a vortex generating column arranged perpendicular to the flow of intake air on the upstream side of the throttle valve 230, and 4 emits ultrasonic waves to the Karman vortices of the intake air generated by this vortex generating column. The ultrasonic oscillator is driven by an ultrasonic generator 4a.

Reference numeral 5 denotes a receiver for receiving the ultrasonic waves from the ultrasonic oscillator 4 modulated by the Karman vortex, and the output of this receiver is frequency-voltage converted by the processing circuit 5a to generate the Karman vortex. A voltage output corresponding to the number (frequency) is obtained, and these constitute a detector that detects the number of Karman vortices.

6 is an air tank that constitutes air chamber A, and 7 is the air chamber A.
This is a communication pipe that communicates with the downstream side of the detector of the intake air conduit 1.

Next, the operation of the device configured as described above will be explained.
The air sucked into the intake air conduit 1 creates Karman vortices in the number corresponding to the flow rate at the rear of the vortex generating column 3, and is sucked in from the intake valve of the internal combustion engine via the throttle valve 2.

The generated vortex mixes a frequency signal corresponding to the vortex with the ultrasonic wave from the ultrasonic oscillator 4, which is received by the receiver 5 and converted into a voltage output corresponding to the air flow rate by the processing circuit 5a. converted. When the manifold primary negative pressure is high, the throttle valve is closed and only partially opened, so the negative pressure surge from the engine's intake valve is reflected by this, and the pressure that partially passes through is also reduced. As mentioned above, it is attenuated by descent and does not affect the intake air of the Karman vortex detector near the population.

Manifold negative pressure is approximately 50m7! From around LH9, the opening area of the throttle valve increases and the orifice effect disappears, and the negative pressure surge that occurs at the moment the suction valve opens advances in the intake air conduit 1 toward the inlet while being attenuated. . Here, the air tank 6 and the intake air conduit 1
The pressure between the two resonates through the communicating pipe 7, and the passing impedance of the traveling wave decreases between them.
Up to this point, the negative pressure surge is absorbed and attenuated, and its influence on the inlet side is suppressed beyond that point, and it does not interfere with the air flow near the Karman vortex detection section. Here, the volume of the air chamber A, the opening position of the communication pipe 7 with respect to the intake air conduit 1, and the communication pipe 7
It is desirable to set the pore diameter to the optimum value experimentally. In this case, since the air tank 6 is connected to the intake air conduit 1 through the communication pipe 7, it can also be connected to the vicinity of the negative pressure surge generation source further downstream from the throttle valve 2, so that it can be effectively It is possible to set the opening position.
Therefore, it is possible to suppress the pulsation of the intake air flow and generate a uniform vortex over the entire range from the high manifold negative pressure to the low manifold negative pressure at the fully open position of the throttle valve. FIG. 2 shows another embodiment of this invention.
The two air chambers A and B are composed of tanks 6a and 6b, and the two air chambers A and B are communicated with the intake air conduit 1 through communication pipes 7A and 7b. Therefore, the range of pressure surge damping effect can be increased.

FIG. 3 shows yet another embodiment of the present invention, in which a pipe 8 with a set diameter and length is provided without a separate tank.
The air chamber A is configured by the air chamber A, which allows communication with the intake air conduit 1 and the configuration of the air chamber A to be performed at the same time.

Even in this embodiment, the same effects as described above can be achieved by appropriately setting the diameter and length of the pipe 8. As described above, according to the present invention, even in a range where the manifold negative pressure near the fully opened throttle valve is low, it is possible to suppress the pulsation of the airflow near the Karman vortex detection part and generate a stable vortex, thereby improving the engine performance. Stable flow rate detection may be possible over the entire operating range.

Furthermore, since the air chamber is communicated with the intake air conduit through the pipe, it is easy to set the communication position with respect to the air conduit, which is advantageous in manufacturing. Furthermore, since the air chamber reduces intake pulsation through resonance in a specific operating state of the internal combustion engine in which air flow pulsation is large, it is possible to effectively reduce intake pulsation in the specific operating state. .

[Brief explanation of the drawing]

1 to 3 are cross-sectional configuration diagrams showing each embodiment of the present invention. In the diagram, 1 is inhalation? 2 is a throttle valve, 3 is a vortex generation column, 4 is an ultrasonic oscillator, 5 is a receiver, 6 is an air tank, A and B are air chambers, and 7 is a communicating pipe.

Claims (1)

[Claims] 1. A vortex detector that detects the number of vortices in intake air generated by a vortex generation column arranged in an intake air passage of an internal combustion engine so as to be substantially perpendicular to the flow direction of the intake air, and the vortex generator described above. A pipe is provided that connects the intake air passage downstream of the pillar with an air chamber that reduces intake pulsation through resonance in a specific operating state of an internal combustion engine in which intake pulsation is large in the vortex generating section. Intake air flow rate detection device for internal combustion engines.