JPH07128107A - Intake device for engine - Google Patents

Abstract

PURPOSE:To suppress an output variation of a hot wire airflow meter and to accurately control an engine in an intake device for the engine having the airflow meter. CONSTITUTION:The air sucked from an air cleaner inlet 1 is passed through a circumferential element 3, collided near a central shaft of an air cleaner case 2, and combined. Further, an air flow is bent substantially perpendicularly by a duct 5. A straightening plate 6 provided in the duct 5 controls a separation flow due to abrupt change of the flow and has a straightening operation for turbulence due to collision (combining) pear the central shaft of the case, thereby suppressing an output variation of a hot wire airflow meter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine air intake system using a thermal air flow meter applied to an automobile engine, for example, to suppress output fluctuation of the thermal air flow meter and to perform highly accurate engine control. It is intended.

[0002]

2. Description of the Related Art Recently, as a method for measuring an air flow rate, a thermal air flow meter, for example, a hot wire type flow meter has been widely used. This hot-wire type flow meter has an advantage that the mass of intake air can be directly detected. Further, the flow rate of a part of the flow passage cross section is measured by the change of the heat transfer amount from the heating resistor, which is smaller than the flow passage diameter, to measure the entire flow rate.

Therefore, it is easily affected by the turbulence of the flow from the air cleaner. In particular, if there is a sudden change in the flow (a sharp bend) near the air cleaner outlet, the turbulence increases as shown in FIG. As described above, when the turbulence from the air cleaner, that is, the flow velocity fluctuation is large, the output fluctuation of the flow meter also increases as shown in the conventional example of FIG. 3, which adversely affects the engine control.

Therefore, as shown in FIG. 5, an intake structure is proposed in which a rectifying grid 100 is provided at the outlet of the air cleaner to suppress fluctuations in the output of the flow meter (Japanese Patent Laid-Open No. 57-10301).
6). In FIG. 5, 10 is an air cleaner, 1 is an inlet portion of the air cleaner, 2 is an air cleaner case,
3 is an element, 8 is a sensor part, and 101 is a mesh member.

[0005]

As shown in FIG. 5, when a rectifying grid 100 is provided in the flow passage, fluctuations in the output of the flow meter are suppressed, but intake resistance increases and engine output decreases. There are many problems such as. In view of the above problems, an object of the present invention is to provide an engine intake device that does not adversely affect engine control, that is, suppresses output fluctuation of a thermal air flow meter without reducing engine output.

[0006]

According to the present invention for solving the above-mentioned problems, an engine intake device includes an air cleaner,
An air intake device for an engine, comprising: a thermal type air flow meter which is provided on a downstream side of air flowing into the air cleaner and measures a flow rate of air flowing into the engine, wherein the air cleaner includes an air cleaner case (2); From an element that is housed in the air cleaner case (2) and removes dust from the passing air, and a duct (5) that guides the air flowing out from each part of the element and joined to the thermal air flow meter from the air cleaner case (2). The duct (5) has a flow path bent so as to take the merged air into an inside of the air cleaner case through an opening provided in a plane portion of the air cleaner case and guide the air in a direction parallel to the plane portion. A straightening vane (6) is provided inside the duct (5), and the straightening vane (6) extends long along the curved flow path. End faces the air cleaner case bent on the opening side opening of, and the other end is made of a plate-like member out extending towards said thermal air cleaner side.

[0007]

According to the above-described structure of the present invention, the air flowing out from the opening of the air cleaner case collides and joins in the vicinity of the central axis of the air cleaner case, and the flow is bent at a substantially right angle at the bent portion of the duct. On the other hand, in the bent portion of the duct, the curvature is set to be substantially equal to the flow, and the straightening vanes are arranged without impairing the intake resistance.

As a result, the separated flow due to the sudden change in the flow at the bent portion of the duct can be suppressed. Therefore, the output fluctuation of the thermal air flow meter can be suppressed without lowering the output of the engine.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. An embodiment in which the present invention is applied to an intake system for a gasoline engine mounted on a vehicle will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, it comprises an air cleaner 10 and a thermal air flow meter 7 integrally connected to the air cleaner 10 on the downstream side thereof. The air cleaner 10 has a cylindrical air cleaner case 2 and a hollow cylindrical element 3 housed in the air cleaner case 2. Further, the air cleaner case 2 has an air cleaner cap 11.

The air cleaner cap 11 forms a part of the air cleaner case 2, and an opening 4 is formed in a central portion to be joined to the air cleaner case 2.
a disk-shaped lid portion 4 having a, and this lid portion 4
Constitutes the plane portion of the air cleaner case. Further, a duct 5 which forms an intake passage and is connected to the thermal air flow meter 7 is present as a part of the air cleaner 10. The duct 5 has an inlet facing the opening 4a at the center of the lid portion 4 and an outlet connected to the thermal air flow meter 7.

A current plate 6 is arranged in the duct 5 so as to divide the flow path into two parts. This straightening plate 6 has one end 6a
Is a plate-like member having a smooth curvature and hanging toward the opening 4a of the lid portion 4, and the other end 6b extends toward the thermal air flow meter 7 side. The duct 5 and the air cleaner cap 11 are made of metal, and the duct 5 and the lid portion 4 are joined by welding.

Further, as shown in FIG. 2, the duct 5 is composed of an upper portion 5a and a lower portion 5b (the dividing surface 5c is indicated by a one-dot chain line), and these 5a and 5b are joined by welding. Also, the duct 5 is about 90 in consideration of the vehicle mounting space.
° It has a bent shape. And the current plate 6
Has at least a portion between the upper portion 5a and the lower portion 5b.

In the intake device having the above-mentioned structure, the air sucked from the air cleaner inlet portion 1 passes through the circumferential element 3 and then collides with the air cleaner case 2 in the vicinity of the central axis of the air cleaner case 2. Can be bent into. The rectifying plate 6 provided in the duct 5 suppresses the separated flow due to a sudden change in the flow, and also exerts a rectifying action against turbulence due to collision (merging) in the upstream (near the central axis of the air cleaner case).

With this operation, the fluctuation of the output of the thermal air flow meter can be suppressed to a small level, and highly accurate engine control becomes possible. The output fluctuation of the thermal type air flow meter by the above-mentioned intake device is shown in FIG. 3 in comparison with the conventional example. Since the duct 5 of the straightening vane 6 is composed of two members, that is, the upper portion 5a and the lower portion 5b, the straightening vane 6 can be used by utilizing this configuration.
It can be relatively easily manufactured by welding the upper part 5a and the lower part 5b after welding to the a or the lower part 5b. It goes without saying that a plurality of the current plate 6 may be provided if necessary.

In FIG. 1, 9 is a pipe connecting the thermal air flow meter 7 and the engine, and 8 is a sensor section in the thermal air flow meter 7.

[0016]

As described above, according to the intake system of the present invention, the output fluctuation of the thermal air flow meter can be suppressed to a small level without lowering the output of the engine due to the rectifying plate in the duct, and it is highly accurate. There is an excellent effect that the engine can be controlled.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an intake device according to an embodiment of the present invention.

FIG. 2 is an external view of the embodiment corresponding to FIG.

FIG. 3 is a comparative output fluctuation characteristic diagram of the thermal air flow meter of the above-mentioned one embodiment and the conventional example.

FIG. 4 is a sectional view showing a main part of a conventional example.

FIG. 5 is a schematic cross-sectional view showing still another conventional example in which a rectifying grid is stacked.

[Explanation of symbols]

 10 Air Cleaner 7 Thermal Air Flow Meter 2 Air Cleaner Case 3 Element 5 Duct 4 Lid Forming Plane of Air Cleaner Case 4a Opening 6 Rectifier Plate 6a Rectifier Plate One End 6b Rectifier Plate Other End

Claims (1)

[Claims] 1. An intake system for an engine, comprising: an air cleaner; and a thermal air flow meter provided downstream of air flowing into the air cleaner to measure a flow rate of air flowing into the engine. , An air cleaner case (2), an element for removing dust from air passing through the air cleaner case (2), and air flowing out from each part of the element and joined to the thermal cleaner air flow meter from the air cleaner case (2). And a duct (5) for guiding the combined air into the inside of the air cleaner case through an opening provided in the plane portion of the air cleaner case and guiding the merged air in a direction parallel to the plane portion. The duct (5) has a bent flow path, and a current plate (6) is provided inside the duct (5). A plate-shaped member that extends along the flow path and has one end bent toward the opening side of the air cleaner case to face the opening and the other end that extends toward the thermal air cleaner side. An air intake device for the engine.