JPH06102077A - Passage structure of sucked air - Google Patents

Abstract

PURPOSE:To keep the accuracy of an air flowmeter by improving the passage structure of sucked air. CONSTITUTION:An air cleaner has a cross-sectional area wider than that of its inlet part 12 and that of its outlet part 13 where an air flowmeter is arranged and has a passage structure having projections 15-22 provided to the inner wall surface thereof along the flow line distribution of sucked air becoming linear with respect to the air flowmeter. By this constitution, the accuracy of the air flowmeter is kept and noise is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake passage structure from an air cleaner of an internal combustion engine to an air flow meter.

[0002]

2. Description of the Related Art Conventionally, as an apparatus of this type, for example, there is an intake passage described in Japanese Utility Model Laid-Open No. 62-49659. In this passage structure, air is expanded at the inlet of the air cleaner, and at the outlet of the air cleaner where the air flow meter is arranged, the air expanded at the inlet is compressed.

[0003]

The above-mentioned prior art does not take into consideration the air flow in the air cleaner in which the air passage is large, and the change in the air flow velocity distribution in the air cleaner causes an error in the air flow rate measurement. There is a problem,
It is difficult to maintain the measurement accuracy of the intake air flow rate.

An object of the present invention is to provide an intake passage structure capable of rectifying the air flow velocity distribution in the air cleaner and measuring the air flow rate with high accuracy.

[0005]

The above object is to provide an intake air passage structure comprising an air flow meter for measuring the intake air amount of an internal combustion engine, and an air cleaner provided upstream of the air flow meter. The air cleaner has a wider cross-sectional area than the inlet part and the outlet part where the air flow meter is arranged, and the inner wall surface is provided with protrusions along the flow velocity distribution so that the intake air is aligned with the air flow meter. This is achieved by providing an intake air passage structure characterized by being provided.

[0006]

[Function] By providing the protrusion on the inner wall of the air cleaner so that the air flow from the air suction port of the air cleaner to the air flow meter is in a straight line, the flow velocity distribution in this passage does not change significantly. .

[0007]

An embodiment of the present invention will be described below with reference to the drawings. When the intake inlet 12, the intake outlet 13 and the sub-flow passage 5 are aligned with each other as shown in FIG. 1, the heating resistor 1 and the temperature compensating resistor 2 which constitute the sensor element of the air flow meter are provided.
Is fixedly supported by the support pins 3, 3a, 4, 4a, and is arranged in the sub-channel 5. On the other hand, these support pins 3, 3
The other ends of a, 4, 4a are connected to an electronic circuit section 7 made of a substrate on which a thick film firing circuit is formed. The sensor unit 6 integrated with the electronic circuit unit 7 is arranged in the main passage 8 of the air flow meter and fixed by a screw or the like (not shown). The body 9 forms the main flow path 8 which is basically cylindrical. A sub-flow passage 5 that is parallel to the main flow passage 8 and has an inlet opening is provided at the center of the main flow passage 8 at the tip of the protrusion 10 that is formed integrally with the body 9. Further, the protruding portion 10 is provided with a hole penetrating from the outside of the body 9. An intake duct 11 is attached downstream of the body 9. Next, an intake outlet 13 is provided upstream of the other end of the body 9, an air cleaner element 14 is disposed further upstream thereof, and an intake inlet R is provided further upstream thereof to smooth the air flow. There is an air cleaner shaped at 12. The inner wall surface of the air cleaner has projections 15, 16, 17, 1 for rectifying the air flow path.
8, 19, 20, 21, 22 are arranged. Further, an intake duct 23 is attached upstream of the air cleaner.
The flow a that has entered from the intake duct 23 is air-expanded at the intake inlet 12 and separated into b, c, and d, and the flow c becomes the flow e as it is and becomes the flow j that flows into the auxiliary flow path 5. The flow b becomes a flow f rectified by the projections 15 and 16 whose length gradually changes, and is rectified by the projections 17 and 18 whose length changes further toward the sub-flow path 5. It changes to a flow g. The flow d becomes a flow i toward the sub flow path due to 19, 20, 21, and 22 in which the lengths of the protrusions are changed as in the above. Further, the flows e, g, and i going toward the sub-flow passage 5 are air-compressed into one and become a flow j with little turbulence, pass through the sub-flow passage 5 and become flow j, pass through the intake duct 11, and go to the engine. It is composed. FIG. 2 is an example when the intake inlet 12, the intake outlet 13, and the auxiliary flow path 5 are not on the same straight line. The flow a entering from the intake duct 23 is divided into flows b, c and d at the intake inlet 13. The flow b is formed by the projections 15, 16, 17, 18 that gradually decrease in length, and thus the sub-flow path 5
The flow g is rectified toward the flow g, and the flow is rectified toward the sub-flow path by the projections 19, 20, 21, and 22 whose lengths are gradually changed, and further the flow c.
Is a flow e, and the flows e, g, and i are flow j toward the sub main path and flow into the sub flow path 5.

Even if the position of the sub-flow path 5 of the air flow meter is changed as shown in FIGS. 3 and 4, the air flow line can be changed by changing the lengths of the protrusions. As with FIG. 2, the accuracy of the air flow meter can be maintained.

Although the present embodiment has described the hot wire type air flow meter, the air flow meter is not limited to the hot wire type air flow meter because the present invention has the passage structure of the intake air inside the air cleaner.

[0010]

According to the present invention, since the length of the projection in the air cleaner is changed with respect to the air flow meter sub-flow passage, the expanded air stream line is linear with respect to the sub-flow passage. The line becomes a line, and the volume of the air cleaner can be made uniform with respect to the air flow meter due to the change in the protrusion.
Due to these, high accuracy of the air flow meter is maintained and noise is reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an intake air passage structure showing an embodiment of the present invention.

FIG. 2 is a sectional view of a passage structure for intake air according to another embodiment of the present invention.

FIG. 3 is a sectional view of a passage structure for intake air.

FIG. 4 is a sectional view of a passage structure for intake air.

[Explanation of symbols]

1 ... Heating resistor, 2 ... Temperature compensation resistor, 3, 3a,
4, 4a ... Support pins, 5 ... Sub flow path, 6 ... Sensor part, 7 ...
Electronic circuit part, 8 ... Main flow path, 9 ... Body, 10 ... Projection part,
11, 23 ... Intake duct, 12 ... Intake inlet, 13 ... Intake outlet, 14 ... Element, 15, 16, 17, 18, 1
9, 20, 21, 22, ... Protrusions, a, b, c, d, e,
f, g, i, j, k ... Air flow.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G01F 1/00 G 9107-2F 1/68

Claims (3)

[Claims] 1. An intake air passage structure comprising an air flow meter for measuring the amount of intake air of an internal combustion engine, and an air cleaner provided on the upstream side of the air flow meter, wherein the air cleaner has an inlet portion, and A passage structure for intake air, which has a larger cross-sectional area than the outlet where the air flow meter is arranged, and projections are provided on the inner wall surface so that a large amount of intake air can be taken in easily with respect to the air flow meter. . 2. An intake air passage structure comprising an air flow meter for measuring the amount of intake air of an internal combustion engine, and an air cleaner provided upstream of the air flow meter, wherein a plurality of protrusions are provided on the inner wall surface. And the height of the protrusion is increased from the upstream side to the downstream side in sequence. 3. A bypass passage inlet of the air flow meter in an intake air passage structure comprising an air flow meter for measuring an intake air amount of an internal combustion engine, and an air cleaner provided upstream of the air flow meter. The intake air passage structure is characterized in that the portion is provided substantially at the center of the main passage.