JPH0346199Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an intake system for an engine.

(Prior Art) In order to precisely control the air-fuel ratio of an automobile engine, it is necessary to accurately measure the amount of intake air. Conventionally, this measurement has been carried out by providing a hot wire air flow meter in the intake passage and inputting the output signal of this air flow meter to an electronic control device. However, unless the intake air flow around the hot wire air flow meter is sufficiently rectified, the flow state of the intake air will not be constant, so there is a problem that the output value of the hot wire air flow meter will become unstable. Ta.

In an attempt to solve this problem, it is known that an intake air flow measuring device has a main intake passage and a bypass passage equipped with a hot-wire air flow meter, and a rectifying grid is provided on the upstream side of both passages (for example, in actual use). Showa 57-
(Refer to Publication No. 166123) However, in such a device, if the rectifying grid is made finer, the accuracy of intake air amount measurement will be improved by sufficient rectification of the intake air, but on the other hand, there is a risk that the flow resistance of the intake air will increase. Rougher rectifier grids reduce the flow resistance of intake air, but the rectification effect becomes insufficient, resulting in a decrease in the accuracy of intake air volume measurement, which is a problem in which measurement accuracy and elimination of flow resistance are not compatible. It was hot.

(Purpose of the invention) In view of the above-mentioned conventional problems, the present invention stabilizes the output value of the hot wire air flow meter without increasing the flow resistance of the intake air, thereby making it possible to accurately measure the intake air flow rate. The present invention provides an intake system for an engine.

(Structure of the invention) Means for achieving the above-mentioned object of the invention is that in an engine having a bypass intake passage branched from a main intake passage and equipped with a hot-wire air flow meter, a rectifier plate is provided upstream of the bypass intake passage branch part. The baffle plate is characterized in that the mesh upstream of the bypass intake passage is smaller than that upstream of the main intake passage.

The function of the means is that the flow of intake air in both the main intake passage and the bypass intake passage is rectified by the rectifying plate provided on the upstream side of the main intake passage and the bypass intake passage. Due to being made smaller than other parts,
The intake air in the bypass intake passage is rectified to an appropriate state that can be accurately measured by a hot wire air flow meter.

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

1 to 3 show an intake system 1 for an automobile engine. Inside the intake system 1, there is a main intake passage 2 formed in the shape of a ventilate,
A bypass intake passage 3 branched from the main intake passage and provided with a hot wire air flow meter 4 is provided in parallel. A grid-shaped rectifying plate 5 is provided upstream of the main intake passage 2 and the bypass intake passage 3 (on the right side in FIG. 1). The rectifying grid 5 has a relatively coarse mesh, and the upstream portion of the bypass intake passage 3 is formed into a grid-like fine mesh rectifying plate 5a having a smaller mesh than other portions. Furthermore, the bypass intake passage 3 is formed into a spiral passage 3a from the downstream side (see Fig. 3), and its end communicates with a bypass outlet 3b bored on the downstream side of the main intake passage 2. In the middle part of 3,
The hot wire 4a of the hot wire air flowmeter 4 is provided exposed.

In FIG. 4, an air cleaner 6 is connected to the upstream side of the intake device 1, and the downstream side of the intake device 1 is connected to an intake port 8b of a cylinder head 8a of an engine 8 via a throttle body 7.
8c is the cylinder block, 8d is the piston, 8e
is an exhaust port.

It should be noted that the above-mentioned current plate 5 and fine mesh current plate 5a may have a wire mesh shape instead of the lattice shape of this example.

Next, the operation of this embodiment will be described.

During the intake stroke of the engine 8, the intake air sucked into the intake system 1 via the air cleaner 6 branches into the main intake passage 2 and the bypass intake passage 3, passes through both passages 2 and 3, and then joins again. The air is sucked into the cylinder of the cylinder block 8c from the intake port 8b of the engine 8. At this time, the intake air flowing into the main intake passage 2 is
The flow of intake air required by the engine 8 is rectified by this. On the other hand, the intake air that has been sufficiently rectified by the thin mesh rectifier plate 5a flows into the bypass intake passage 3 without irregularly varying its speed. Therefore, the output value of the hot wire air flowmeter 4 is kept stable, so that the intake air flow rate can be accurately measured.

(Effect of the invention) With the above configuration, the present invention provides a main intake passage and a bypass intake passage branched from the main intake passage and equipped with a hot wire air flow meter in parallel, and rectifies the air upstream of both intake passages. In addition to providing a mesh plate, the current plate upstream of the bypass intake passage is made of a smaller mesh than the current plate upstream of the main intake passage, so the speed of intake air flowing through the bypass intake passage is stabilized, and the engine intake air flow rate measured by the hot wire air flowmeter is stabilized. Not only can the amount be measured accurately, but the current plate also has the advantage of minimizing the increase in flow resistance of intake air.

[Brief explanation of drawings]

The drawings illustrate an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional side view of an engine intake system, FIG. 2 is a view taken in the direction of the arrow in FIG. 1, and FIG. 3 is a sectional view taken along the - line in FIG. 1. , FIG. 4 is a longitudinal sectional side view showing other structural parts adjacent to the intake device of FIG. 1. 1...Intake device, 2...Main intake passage, 3...
...Bypass intake passage, 4...Hot wire air flow meter,
5... Current plate, 5a... Fine mesh current plate.

Claims (1)

[Scope of utility model registration request] In an engine having a bypass intake passage branched from the main intake passage and equipped with a hot-wire air flow meter, a baffle plate is provided upstream of the bypass intake passage branch, and the baffle plate is arranged so that the bypass intake passage is separated from the main intake passage. An engine intake system characterized in that a mesh upstream of a passage is made smaller.