JPS5828622A - Detecting device for air quantity - Google Patents

Abstract

PURPOSE:To prevent entering of carbon and oil in a by-pass passage, by providing a plate material bearing dynamic pressure of an air flow at an upstream side of an inlet of a pipe disposed at the by-pass passage. CONSTITUTION:A plate material 10 bearing dynamic pressure of an air flow is fixed at an upstream of an inlet of a pipe 9 and an inlet of the pipe 9 is opened at a downstream side almost in the center of the plate material 10. Therefore, the air having small inertia reaches the downstream side by making a round at the side surface from the upstream side of the plate material 10 and enters from the inlet opening part of the pipe 9. While, in case of dust, carbon and an oil drop having large inertia, the direction of them is changed by the plate material 10 and they hardly enter the inlet of the pipe 9 opened at the downstream side of the plate material 10 and carbon, etc. do not enter a by-pass passage 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air amount detection device for an electronic fuel supply system,
In particular, the present invention relates to an air amount detection device using a hot wire.

First, a conventional air flow rate detection device will be explained based on FIG.

In FIG. 1, reference numeral 1 denotes an air amount detector main body, in which an intake passage 2 is formed, and a venturi part 4 and an airphone part 5 are formed in the intake passage. A land portion 5A is formed on one side of the airphone portion 5, and a bypass passage 6 is provided in this land portion 5A, and a pipe 9 is inserted into the inlet of the bypass passage 6. It opens within the projection section 3 and approximately at right angles to the axis of the venturi section 4. A hot wire 7 is provided in the middle of the bypass passage 6, and the output of the hot wire 7 is sent to a detection circuit 8 fixed to the main body of the air amount detection device and electrically processed. That is, by detecting the amount of air flowing through the bypass passage 6, the amount of air flowing through the intake passage 2 is determined, and from this, the amount of fuel supplied to the internal combustion engine is determined.

The above devices are already well known. By the way, in the above-described system, there is a tendency for small dust, oil droplets, carbon, etc. that have passed through the filter to enter the air horn section together with the air from the air cleaner, and further flow into the bypass passage.

So the heat generated by this dust, oil droplets, and carbon in the bypass passage? There was a problem in that the air amount adhered to lJ7 and its output changed, making it impossible to accurately detect the amount of air.

SUMMARY OF THE INVENTION An object of the present invention is to provide an air amount detection device having a structure that prevents people from getting carbon or oil into the bypass passage.

A feature of the present invention is that a plate material subjected to the dynamic pressure of the air flow is provided upstream of the inlet of the pipe provided in the bypass passage.

However, the same reference numerals as in FIG. 1 indicate the same parts.

In FIG. 2, a plate member 10 that receives the dynamic pressure of air flow is fixed to the upstream side of the inlet of the pipe 9, and the pipe 9. The entrance is open. Therefore, air with low inertia travels from the upstream side of the plate material around the side surface to the downstream side, and enters through the inlet opening of the pipe. On the other hand, since dust, carbon, and oil droplets with large inertia are redirected by the plate 10, it becomes difficult for them to enter the entrance of the pipe 9 that opens on the downstream side of the plate 10, and carbon and oil droplets enter the bypass passage 6. This eliminates the problems caused by Here, the size of the plate 10 is larger than a circle having a diameter that is more than twice the diameter of the pipe 9, and the distance between the plate 10 and the inlet of the pipe 9 is θ~2 of the diameter of the vibrator 9.
Experiments have shown that good effects can be obtained within twice the amount. In addition, it is desirable that the air intake passage supplied to the engine has a small ventilation resistance, and therefore the diameter of the pipe 9 should be 2
A plate material about twice that size is most preferable.

As another example, a plate 10A may be attached to the case of the air cleaner 11 as shown in FIG. 4, or a plate 10B may be integrally formed on the support member 12 of the pipe 9 as shown in FIGS.
But you can get the same effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional air amount detection device, a sectional view of a second air amount detection device, FIG. 5 is a sectional view of an air amount detection device according to another embodiment of the present invention, and FIG. FIG. 5 is a plan view of FIG. 5; 2... Intake passage, 4... Venturi section, 6... Bypass passage, 7... Hot wire, 8... Detection circuit, 9...
・Pipe, 7″#1 3′ Fig. 1

Claims (1)

[Claims] 1. A throttle valve provided in the intake passage and a venturi part formed in the intake passage upstream of the throttle valve; a bypass passage communicating the venturi part upstream of the venturi part; a hot wire disposed in the bypass passage; and the venturi part formed in the intake passage upstream of the throttle valve; Instructing an air amount detection device consisting of a detection circuit that calculates the amount of air passing through the venturi section based on the output of the hot wire, a pipe opening perpendicular to the air flow near the center of the intake passage is installed at the entrance of the bypass passage. An air amount detection device that communicates with the pipe and includes a plate member above the inlet of the pipe that receives the dynamic pressure of the air flowing through the intake passage.