JPH0736103Y2 - Throttle device with air flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a throttle device with an air flow meter.

B. Prior Art FIGS. 1 and 2 show an example of a throttle device with an air flow meter previously proposed by the present applicant.

In the figure, a throttle valve 2 is rotatably supported by a shaft 3 on a throttle body 1, and a hot-wire air flow meter 5 is provided upstream of the throttle valve 2 across an intake passage 4 in the throttle body 1. The air flow meter 5 includes a main body 5a installed across the intake passage 4 upstream of the throttle valve 2 and a main body facing upstream of the intake passage 4.
An air inlet 5b opening to 5a, a heating wire 5c provided in the vicinity of the air inlet 5b and electrically heated, a passage 5d connected to the air inlet 5b and formed in the extending direction inside the main body 5a, and this passage 5d has an air outlet 5e which is connected to the opposite side of the air inlet 5b and is open to both side surfaces and the lower surface of the main body 5a, and the flow rate of air passing through the passage 4 is detected from the resistance value of the heating wire 5c.

On the other hand, the throttle body 1 is provided with a bypass passage 7 that bypasses the throttle valve 2, and an idle control valve 6 is provided therein. Bypass passage 7
Communicates between an air inlet 7a opening upstream of the throttle valve 2 and an air outlet 7b opening downstream of the throttle valve 2, and the air flowing into the bypass passage 7 from the air inlet 7a flows at the idle control valve 6. Adjusted to the engine combustion chamber. Therefore, the idle speed can be controlled by the idle control valve 6.

In this conventional device, as shown in FIG. 8 (a), the air outlet 5e of the hot-wire air flow meter 5 and the air inlet 7a of the idle control valve 6 are located at 90 degrees with respect to each other about the axis 4X of the intake passage 4. It is formed with an angle. Also,
As shown in (b), the air outlet 7b of the idle control valve 6 forms an angle of about 90 degrees with the air inlet 7a, and is formed in line with the air outlet 5e of the air flow meter 5.

C. Problem to be Solved by the Invention However, the conventional throttle device has a problem that the measurement accuracy of the air flow rate is poor particularly when the throttle valve 2 is almost closed.

The present inventor has made extensive studies as to the cause of poor measurement accuracy, and has reached the following conclusion.

When the throttle valve 2 is almost closed,
Approximately −500 m between the air inlet 7a and the air outlet 7b in the intake passage 4.
A differential pressure of mHg occurs. The flow rate between the air inlet 7a and the air outlet 7b is determined in proportion to the opening area of the idle control valve 6. When the flow velocity distribution in the intake passage 4 is measured under such conditions, the air inlet of the idle control valve 6
The flow velocity in the vicinity of 7a is the maximum, and the flow velocity in the vicinity of the air outlet 5e of the air flow meter 5 is not so fast. Therefore, an error occurs between the air flow rate actually passing through the idle control valve 6 and the air flow rate measured by the air flow meter 5, resulting in poor measurement accuracy.

The technical problem of the present invention is to improve the measurement accuracy of the air flow rate in this type of throttle device.

D. Means for Solving the Problems The present invention will be described with reference to FIGS. 1 to 3 showing an embodiment. A throttle device according to the present invention is arranged rotatably in a throttle body 1 and is provided with an intake passage 4. The throttle valve 2 that controls the opening area, the bypass passage 7 that connects the upstream side and the downstream side of the throttle valve 2 and the air flow rate that bypasses the throttle valve 2 installed in the bypass passage 7 are adjusted to adjust the engine idle speed. An idle control valve 6 for controlling the air flow rate and a hot-wire air flow meter 5 provided in the intake passage 4 are provided.

The bypass passage 7 is provided in the throttle body 1 so as to face the intake passage 4 upstream of the throttle valve 2 and in the throttle body 1 so as to face the intake passage 4 downstream of the throttle valve 2. Air outlet
Communicate with 7b.

The air flow meter 5 includes a main body 5a installed upstream of the throttle valve 2 across the intake passage 4, an air inlet 5b facing the intake passage 4 and opening to the main body 5a, and the air inlet 5b.
Heat wire 5c installed near the
A passage formed in the extending direction inside the main body 5a.
5d and an air outlet 5e opening to the main body 5a facing the intake passage 4 connected on the opposite side of the air inlet 5b of the passage 5d.
The flow rate of air passing through the inside of 5d is detected from the resistance value of the heating wire 5c.

The above technical problem is, for example, as shown in FIG.
This can be solved by opening the air inlet 7a of the bypass passage 7 within a range of approximately ± 30 degrees distributed around the axis 4X of the intake passage 4 with respect to the air outlet 5e of the hot-wire air flow meter 5.

E. Action The air outlet 5e of the air flow meter 5 is arranged in the vicinity of the bypass passage inlet 7a where the flow velocity in the intake passage has the maximum value, and the flow rate of the air passing through the inside of the air flow meter 5 is 7
Is almost proportional to the flow rate of air passing through. As a result, the measurement accuracy of the bypass air flow rate by the air flow meter 5 is improved.

It should be noted that, in the above D and E for explaining the configuration of the present invention, the drawings of the embodiments are used to make the present invention easy to understand, but the present invention is not limited to the embodiments.

F. Embodiment The throttle device according to the present invention has exactly the same basic structure as that shown in FIG. 1 and FIG. 2, and only the opening positions of the air inlet 7a and the air outlet 7b of the bypass passage 7 are different. .

That is, as shown in FIG. 3, the angle θ between the air outlet 5e of the air flow meter 5 and the air inlet 7a of the bypass passage 7 is set to 30 °, and the bypass passage outlet is formed.
The angle φ formed by 7b and the air outlet 5e of the air flow meter 5 is 90
I try to make it happen.

That is, in this type of throttle device, the flow velocity near the bypass passage inlet 7a has the maximum value, so the air outlet 5e of the air flow meter 5 is arranged near the maximum flow velocity. As a result, the flow rate of air passing through the air flow meter 5 is substantially proportional to the flow rate of air passing through the bypass passage 7, thereby improving the measurement accuracy of the air flow meter 5.

The inventor of the present invention uses ΔQ / Q (measured air flow rate by the air flow meter 5 / intake passage as a parameter) based on the positional relationship between the air flow meter air outlet 5e and the bypass passage inlet 7a as shown in FIGS. The inflow air flow rate) is plotted on the ordinate, and the inflow air flow rate Q is plotted on the abscissa. When θ = 0 °, ± 30 °, 45 °, 90 ° were selected and measured as the above parameters, the results shown in FIGS. 5 to 7 were obtained.

According to FIG. 5, by setting θ = 0 °, -2.8
Accuracy of up to 1.8% was obtained, and according to Fig. 6, θ = ± 30 °
When set to, an accuracy of -2.2 to 4% was obtained.
Further, according to FIG. 7, when setting θ = 45 °, the accuracy is −6.0 to 1.6%, and when setting θ = 90 °, the accuracy is −7.2 to 0.8%. As a result,
It was confirmed that the desired measurement accuracy could be achieved if == 30 °.

In the above embodiment, the angle φ formed by the bypass passage outlet 7b and the airflow meter air outlet 5e is set to 90 degrees, but it is not limited to this.

G. Effect of the Invention According to the present invention, the air inlet of the bypass passage is opened within the range of approximately ± 30 degrees distributed around the axis of the intake passage with respect to the air outlet of the hot-wire airflow meter. Therefore, the air outlet of the air flow meter is placed near the inlet of the bypass passage where the flow velocity in the intake passage has the maximum value, and the air flow rate passing through the air flow meter is almost proportional to the air flow rate passing through the bypass passage. The accuracy of measuring the bypass air flow rate by the air flow meter is improved.

[Brief description of drawings]

FIGS. 1 and 2 explain an example of a throttle device according to the present invention. FIG. 1 is a vertical sectional view, FIG. 2 is a vertical sectional view taken along a plane including a bypass passage inlet, and FIG. 3 is an air flow. The figure which shows an example of the positional relationship between a meter air outlet and a bypass passage inlet, FIG. 4 is a figure explaining the measurement accuracy when the positional relationship between an air flow meter air outlet and a bypass passage inlet is used as a parameter, FIG. FIG. 7 is a graph showing the measurement results under each condition of FIG. FIG. 8 is a diagram showing a positional relationship between an air flow meter air outlet and a bypass passage inlet of a conventional device. 1: Throttle body 2: Throttle valve 3: Axis, 4: Intake passage 5: Heat ray type air flow meter 5a: Main body, 5b: Air inlet 5c: Heat ray, 5d: Passage 5e: Air outlet 6: Idle control valve 7: Bypass passage , 7a: Air inlet 7b: Air outlet

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02D 33/00 318 J

Claims (1)

[Scope of utility model registration request] 1. A throttle valve rotatably disposed in a throttle body for controlling an opening area of an intake passage; and an air inlet provided in the throttle body so as to face the intake passage upstream of the throttle valve. A bypass passage communicating with an air outlet provided in the throttle body so as to face an intake passage downstream of the throttle valve; an engine installed in the bypass passage to adjust an air flow amount bypassing the throttle valve An idle control valve for controlling an idle speed of the main body; a main body installed across the intake passage upstream of the throttle valve; an air inlet opening to the main body facing the intake passage; A heating wire that is provided in the vicinity and that is electrically heated, and is connected to the air inlet inside the main body in the extending direction. A passage formed in the passage and an air outlet connected to the air inlet of the passage opposite to the air inlet and opening to the main body facing the intake passage, and detecting the flow rate of the air passing through the passage from the resistance value of the heat wire. A heat wire type air flow meter for controlling the temperature of the intake air passage, the air inlet of the bypass passage being opened within a range of approximately ± 30 degrees distributed about the axis of the intake passage with respect to the air outlet of the heat wire type air flow meter. A throttle device with an air flow meter, which is characterized in that