JPH0792031B2 - Throttle chamber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a throttle chamber forming a part of an intake passage of an internal combustion engine.

<Prior Art> In an internal combustion engine such as a gasoline engine, as is well known, a throttle valve for restricting intake air is provided in an intake passage.

Generally, the passage portion in which the throttle valve is interposed is formed as a single throttle chamber and is assembled by being connected between the upstream end of the intake manifold and the intake pipe connected to the downstream side of the air cleaner.

A conventional structure of such a throttle chamber will be described with reference to FIG. 2 (see Japanese Patent Laid-Open No. 63-5125).

In the drawing, a hot-wire type air flow meter 3 for detecting an intake air flow rate Q is attached to an inlet passage 2 at an upstream portion inside a passage of a throttle chamber 1.

From the inlet passage 2 in which the air flow meter 3 is installed, the throttle portion 4 that constricts the diameter of the passage cross section toward the downstream direction.
And a main passage 6 to which a throttle valve 5 is attached is formed on the downstream side of the throttle portion 4.

Further, a bypass passage 7 is formed which has an inlet opening in the narrowed portion 4 and which bypasses the main passage 6 and extends downstream. An intake manifold connected to the downstream side of the throttle chamber 1 also has a bypass passage continuous with the bypass passage 8, and an idle control valve for controlling the engine speed during idle operation is provided in that portion. It

<Problems to be Solved by the Invention> However, in such a conventional throttle chamber structure, since the inlet of the bypass passage 7 is open to the throttle portion, when the bypass passage 7 is opened as shown in FIG.
As the opening degree of the idle control valve increases, the central axis of the air flow is greatly attracted toward the inlet of the bypass passage 7 by the suction force from the bypass passage 7, and the sensor portion of the air flow meter 3 is provided near the central axis of the passage. Therefore, a considerably large detection error may occur.

The present invention has been made in view of such conventional problems, and an object thereof is to provide a throttle chamber having a structure in which the influence of the detection error of the air flow meter due to the bypass passage is minimized.

<Means for Solving the Problem> Therefore, according to the present invention, an inlet passage equipped with an air flow meter having a sensor portion in the vicinity of the central axis of the passage, a main passage having a throttle valve interposed downstream thereof, and the main passage In a throttle chamber having a bypass passage that bypasses the passage, the inlet passage and the main passage are connected with their axial centers aligned with each other through a throttle portion that narrows the diameter of a passage cross section in a downstream direction. The inlet of the bypass passage is opened in the main passage wall on the downstream side of the downstream end of the throttle portion.

<Operation> The air sucked into the throttle chamber can be made to have the central axis of the flow sufficiently close to the central axis of the passage by the throttle portion, so that the sensor portion in the vicinity of the central axis of the passage of the air flow meter provided upstream thereof. With this, the flow rate can be detected accurately.

<Example> Below, the Example of this invention is described based on drawing.

In FIG. 1 showing the configuration of one embodiment, a hot wire type air flow meter 13 is provided in an inlet passage 12 of a throttle chamber 11.
As in the conventional case, the sensor portion 13a is mounted in the vicinity of the central axis of the passage.

The downstream end of the inlet passage 12 is conventionally provided with an air flow meter 13
And a constricted portion 14 is formed continuously with the downstream end so as to constrict the passage diameter in the downstream direction.

Then, a main passage 16 connected to the downstream end of the throttle portion 14 and having a throttle valve 15 interposed is formed with the passage central axis coinciding with the inlet passage 12, and the inlet is opened in the passage wall of the main passage 16 to be downstream. A bypass passage 17 extending to the side is formed.

In the throttle chamber 11 having such a structure,
When the idle control valve (not shown) is opened, when the air sucked into the throttle chamber 11 reaches the main passage 16 from the inlet passage 12 through the throttle portion 14, the central axis of the flow is sufficient due to the throttle action. Close to the central axis of the passage.

Therefore, even if the central axis of the flow is pulled toward the inlet on the downstream side of the throttle section 14 by the suction force from the inlet of the bypass passage 17, the influence is as small as possible on the upstream side of the throttle section 14. When the air flow meter 13 is attached, the central axis of the flow is substantially aligned with the central axis of the passage where the sensor portion 13a is located.

As a result, the intake air flow rate Q by the air flow meter 13
It is possible to maintain excellent detection accuracy of.

<Effects of the Invention> As described above, according to the present invention, since the inlet of the bypass passage is opened on the downstream side of the throttle portion of the throttle chamber, the detection error of the air flow meter due to the suction force from the bypass passage is minimized. It can be small and the detection accuracy is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of the present invention, and FIG.
FIG. 3 is a sectional view showing a conventional example, and FIG. 3 is a diagram showing a detection error of the intake air flow rate in the conventional example. 11 …… Throttle chamber, 12 …… Inlet passage, 13 …… Air flow meter, 13a …… Sensor section, 14 …… Throttle section, 15
...... Throttle valve, 16 ...... Main passage, 17 ...... Bypass passage

Claims (1)

[Claims] 1. An inlet passage equipped with an air flow meter having a sensor portion near a central axis of the passage, a main passage having a throttle valve interposed downstream thereof, and a bypass passage bypassing the main passage. In the throttle chamber, the inlet passage and the main passage are connected with their axial centers aligned with each other through a throttle portion that narrows the diameter of the passage cross section in the downstream direction, and the downstream side of the downstream end of the throttle portion. A throttle chamber having a structure in which an inlet of the bypass passage is opened in a main passage wall of the above.