JPS5917372B2 - Internal combustion engine intake air amount measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the intake air amount of an internal combustion engine using Karman vortices.

A fuel injection control device that appropriately controls the mixture ratio of fuel and air in an internal combustion engine requires a device that accurately and responsively measures the amount of air taken in. By the way, the intake air amount of an internal combustion engine pulsates significantly because air is taken in only when the intake valve of the internal combustion engine is opened, and even while the intake valve is open, the air is not taken in at a constant flow rate. Furthermore, if the intake valve and exhaust valve of the internal combustion engine overlap, a backflow occurs in the intake air passage, which further increases the pulsation of the intake air amount. When a Karman vortex flow meter is used to measure the intake air amount of an internal combustion engine, the large pulsations in the intake air amount described above disrupt the generation of the Karman vortex downstream of the vortex generation column and cause measurement errors. be.

This invention has been made in order to improve the above-mentioned problems, and aims to improve detection accuracy by suppressing intake air pulsation in the Karman vortex detection section. Embodiments of the present invention shown in the figures will be described below.

First, in FIG. 1, reference numeral 1 denotes an intake air conduit constituting an intake air passage A of an internal combustion engine 5 (not shown), 2 a vortex generating column installed in the intake air conduit substantially perpendicular to the flow direction of the intake air, and 3 4 is an ultrasonic generator; 4 is an ultrasonic transducer that is driven by this ultrasonic generator and transmits ultrasonic waves to the vortices generated downstream of the vortex generating column 2; 5 is an ultrasonic transducer A receiver receives ultrasonic waves from the transducer, and 6 is a processing circuit that processes the output of this receiver.

Reference numeral 7 denotes a discharge conduit constituting a partial intake air discharge passage B branched from the intake air passage A on the downstream side of the vortex generating section, and 8 is a discharge conduit provided in this discharge conduit 5 and driven by an electric motor or the like (not shown). This is an exhaust blower that forces part of the intake air out.

9 is a throttle valve.

Next, the operation of the embodiment configured in this manner will be explained.

30 The air taken into the intake air passage A is created by the vortex generating column 2 in the downstream part of the Karman vortex, the number of which corresponds to the flow rate, and is taken in from the intake valve of the internal combustion engine via the throttle valve 9.

The vortex generated downstream of the vortex generating column 2 modulates the ultrasonic wave 35 emitted from the ultrasonic transducer 4, and this modulated ultrasonic wave is received by the receiver 5 and sent to the processing circuit 6. The number of vortices generated is output as a frequency. H1- On the other hand, a part of the intake air that has passed through the Karman vortex detection section is drawn into the intake air partial discharge passage B by the exhaust proir 8 and is discharged to the outside of the intake air passage A.

The remaining intake air passes through the throttle valve 9 and is drawn into the internal combustion engine. Here, the intake air of the internal combustion engine is drawn into the cylinder through the intake air passage A by the movement of the piston in the engine cylinder only when the intake valve of the internal combustion engine opens, and the amount of intake air at this time is the average flow. Instead, the intake air reaches its maximum amount a while after the intake valve begins to open, and after that, the piston approaches the bottom dead center and its movement speed decreases, causing almost no intake, and the flow of intake air pulsates. This is especially noticeable when the engine speed is low, as the flow in the intake air passage A appears as intermittent pulsations, but in this device, the air is forced to flow to the exhaust passage B by the above-mentioned proar 8. In the Karman vortex detection section, there are no intermittent traces of flow, and flow rate pulsations are suppressed, and flow rate detection errors caused by disturbances in Karman vortex generation due to large flow rate pulsations, especially at low engine speeds, can be prevented.

Note that the Karman vortex detection section detects the sum of the flow rate sucked into the engine and the flow rate discharged by the proar 8, but the flow rate discharged by the proar 8 {preset The intake air flow rate of the engine can be detected by subtracting and correcting the detected flow rate output by the set flow rate.

FIG. 2 shows another embodiment of the present invention, in which a portion of the intake air in the intake air passage A of the embodiment in FIG.
A spiral flow passage 10 is provided between the branch point of the throttle valve 9 and the throttle valve 9.
This is what was installed.

This device also uses the spiral flow passage 10 even when backflow occurs to the intake air passage A due to valve overlap between the intake valve and the exhaust valve of an internal combustion engine.
The long passage of the vortex can sufficiently attenuate the backflow and prevent disturbance of the Karman vortex. As described above, according to the present invention, in the intake air amount measuring device for an internal combustion engine that uses Karman vortices, the vibration of the intake air flow rate of the internal combustion engine is suppressed and the disturbance of the Karman vortices due to the pulsation is prevented. It has become possible to accurately measure the amount of intake air under any condition.

Furthermore, since the structure is simple, it is easy to manufacture and has good durability, making it an excellent device for measuring the amount of intake air in automobile internal combustion engines.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing different embodiments of the present invention. In the figure, A is an intake air passage, 2 is a vortex generating column, 3 is an ultrasonic generator, 4 is an ultrasonic oscillator, 5 is an ultrasonic receiver, 6 is a processing circuit, B is a partial intake air exhaust passage, 8 is discharge proa, 9
1 is a throttle valve, and 10 is a spiral flow passage.

Claims (1)

[Claims] 1. A vortex generating column installed in an intake air passage of an internal combustion engine substantially perpendicular to the flow direction of intake air, and detecting the number of vortices in the intake air generated downstream of this vortex generating column. An internal combustion engine comprising a vortex detector, a partial intake air exhaust passage branched from the intake air passage on the downstream side of the vortex detector, and a blower that forcibly exhausts a part of the intake air from the intake air partial exhaust passage. Engine intake air amount measuring device. 2. The intake air amount of the internal combustion engine according to claim 1, wherein the intake air passage downstream of the branch point of the intake air partial discharge passage includes a spiral flow passage that gives a spiral flow to the intake air. measuring device.