JPH02125962A - Throttle body for engine intake air flow measurement - Google Patents

Abstract

PURPOSE:To improve a measuring precision, by providing a member whose maximum current speed position becomes different at the time of a forward current from at the time of a reverse current, and also, providing the sensor portion of an air current meter at a position where the speed of a current becomes maximum at the time of the forward current, within a bypass flow passage equipped with an air current meter. CONSTITUTION:At a bypass flow passage 1 equipped with an air current meter, an elbow portion 2 is provided, and also, a nozzle portion 4 having a center hole 3 is provided at the upper part of the elbow portion 2. Also, an opening portion 5 is provided at the lower part of the nozzle portion 4, and in addition, an enlarging portion 6 of a truncated cone shape is provided at the lower part of the opening portion 5, and at the same time, a hole 7 is provided at the side wall of the opening portion 5. Moreover, the sensor portion of an air current meter is provided at a position 9 shifted to the elbow exit side from the center position 8 of the enlarging portion 6. Now, at the time of the forward current, for example, of air, the current passing through the hole 3 of the nozzle portion 4 is pushed by a current flowing in through the side hole 7 of the opening portion 5. As a result, a position showing the maximum current speed becomes the one eccentric on the left side, not at the center of the enlarging portion 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air flow rate measuring device, and particularly to a throttle body suitable for measuring the intake air amount of an automobile engine.

[Conventional technology]

The conventional device has a structure in which a bypass flow path equipped with a hot wire air velocity meter is provided in the air flow of the main flow path, as described in Japanese Patent Application Laid-Open No. 61-65053.

[Problem to be solved by the invention]

The above-mentioned prior art does not take into consideration the phenomenon in which air in the throttle body flows in the direction of outflowing from the cylinders of the engine (backflow) in the early stage of the intake process of the engine. Therefore, there was a problem in that the flow velocity fluctuated greatly at the measurement position of the air flow velocity, and the measurement accuracy of the current meter was low.

An object of the present invention is to improve measurement accuracy by reducing the backflow at the position of the air velocity meter and reducing the range of flow velocity fluctuations.

[Means to solve the problem]

The above purpose is to provide a member in a bypass flow path equipped with an air velocity meter with different positions of maximum flow velocity for forward flow and reverse flow,
This is achieved by providing the sensor section of the air flow meter at a position where the flow velocity is maximum during forward flow.

[Effect]

By providing the sensor section of the current meter at a position where the flow velocity is maximum during forward flow, the flow velocity at the sensor section becomes the maximum flow velocity during forward flow, and becomes smaller than the maximum flow velocity during reverse flow. As a result, it is possible to create a flow situation in which the flow velocity is high during forward flow and low during reverse flow, so the current meter is in a state where flow fluctuations are small and measurement accuracy is improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. An elbow portion 2 is provided in a bypass flow path 1 of an air velocity meter. A nozzle part 4 having a hole 3 in the center is provided at the upper part of the elbow part 2, a gap part 5 is provided below the nozzle part 4, and a truncated conical enlarged part 6 is provided below the gap part 5. Further, a hole 7 is provided in the side wall of the gap 5. The sensor part of the hot wire anemometer (air velocity meter) is provided at a position 9 shifted from the center position 8 of the enlarged part 6 toward the elbow exit side. As shown in FIG. 2, the bypass circular pipe flow path 1 is provided in the main air portion of the throttle body 10.

In FIG. 2, when air is being drawn into the engine cylinder (at the time of forward flow), the air flows from above the throttle body 10 to below. On the other hand, bypass circular pipe flow path 1
The flow also goes from top to bottom.

At this time, the flow passing through the hole 3 of the nozzle part 4 in FIG. Flow along 11
becomes. As a result, the position where the maximum flow velocity of the airflow exiting the hole 3 of the nozzle part is not at the center of the enlarged part 6 but at a position biased to the left. Therefore, hot wire anemometers measure the maximum flow velocity of the air flow. On the other hand, at the beginning of the engine's intake stroke, the pressure inside the cylinder is higher than that inside the throttle body, so a backflow occurs from the bottom to the top. At this time, backflow also occurs within the bypass circular pipe flow path 1. The air changes its direction from horizontal to vertically upward at the elbow 2, and the position of maximum flow velocity shifts to the right of the center of the enlarged portion 6 due to centrifugal force. Since the sensor part of the hot wire anemometer is on the left side of the enlarged part 6, the flow velocity to be measured is
Less than maximum flow velocity. While the engine is rotating, the suction process is periodically repeated, and the forward flow and reverse flow are periodically repeated in the sensor section of the hot wire anemometer, causing the flow velocity to fluctuate. Since the flow velocity during reverse flow at the measurement position is small, the current meter can be installed in situations where flow velocity fluctuations are small.
Measurement accuracy is improved.

A second embodiment of the present invention will be explained with reference to FIG.

The bypass circular pipe flow path 1 of the air velocity meter has a structure having an elbow portion 2. A tapered nozzle 12 and an enlarged nozzle 13 are provided at the upper part of the elbow part 2. Hot wire anemometer (air flow meter)
The sensor section is provided at the center position 14 of the tapered nozzle 12. The bypass flow path 1 is provided in the main air portion of the throttle body 10, as shown in FIG.

When the flow in the throttle body 10 is a forward flow from the top to the bottom, the flow in the bypass circular pipe passage 1 is also a forward flow from the top to the bottom. At this time, the tapered nozzle 12 becomes the expanding nozzle 1.
3, the flow resistance is smaller and contraction occurs, so the flow velocity is higher. At position 14 of the sensor section, the flow velocity is maximum. On the other hand, when the flow is reverse, the tapered nozzle 12 has an expanding effect, and the expanding nozzle 13 has a contracting effect. Therefore,
The flow velocity is maximum at the upper end of the enlarged nozzle 13, and the flow velocity at the sensor portion position 14 is smaller than the maximum value.

According to this embodiment, since the flow velocity during reverse flow is small at the flow velocity measurement position, the current meter can be provided in situations where flow velocity fluctuations are small, and measurement accuracy is improved. Moreover, the structure is simple.

〔Effect of the invention〕

According to the present invention, since the current meter can be placed in a situation where the flow velocity during backflow is low, measurement accuracy is improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view (a) and a vertical sectional view (b) of an embodiment of the present invention, and FIG. 2 is a throttle valve equipped with the embodiment of FIG.
A plan view (a) and a longitudinal sectional view (b) of the body, and FIG. 3 are a plan view (a) and a longitudinal sectional view showing a second embodiment of the present invention. 1... Bypass flow path, 4... Nozzle section, 5... Gap, 6 Tin diagram (α-n Diagram 2)

Claims (1)

[Claims] 1. A flow path that guides air taken into the engine, a valve that is located within the flow path and adjusts the amount of air, and a second air flow path that is provided adjacent to the valve. In a throttle body for an automobile fuel supply system comprising a flow meter provided in the second air flow path, the position at which the flow velocity is maximum is determined depending on the direction of the flow in the second air flow path. A throttle body for measuring engine intake air volume characterized by having different parts.