JP2000009513A - Flow rate-measuring device and air cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the fluctuation of flow velocity, to eliminate turbulence, to reduce breathing resistance, to reduce the loss of pressure, and to accurately measure the flow rate of suction air by allowing gas flow being narrowed by a narrowing passage to pass through a flowmeter, and by increasing flow velocity. SOLUTION: When the inner-periphery wall of a narrowing plate is opened in the range of suction-air flow 102 with high flow velocity, the suction-air flow with the high flow velocity and large turbulence directly passes near both resistors, thus increasing the fluctuation of the detection signal of a flow meter 20. In the specific range of both the sides of an imaginary axis line 110 of the narrowing plate, when the inner-periphery wall of an end face 24a of the inlet side of the narrowing plate is opened, the suction-air flow 102 with the high flow velocity collides with any part of the end face 24a, and the suction-air flow 102 is narrowed toward a passage 31 for effectively making uniform the flow velocity, thus reducing the fluctuation of the detection signal of a flowmeter 20, and accurately measuring the flow rate of suction air. When the suction air passes through the passage 31, that part in contact with the passage 31 is limited to an outlet pipe and the inner-periphery wall of the narrowing plate, thus reducing the loss of pressure since the breathing resistance (friction) is small as compared with a rectifying lattice.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a flow measuring device,
The present invention relates to an air cleaner for an internal combustion engine provided with a flow rate measuring device (hereinafter, an “internal combustion engine” is referred to as an engine).

[0002]

2. Description of the Related Art In fuel injection control of an engine, an amount of intake air flowing through an intake passage is measured, and a fuel supply amount to the engine is determined based on the amount of intake air. As a flow rate measuring device for measuring the intake flow rate, for example, a device using a thermal flow meter or a Karman vortex flow meter has been conventionally known. In such a flow rate measuring device, a flow meter is disposed inside an intake passage, for example, at an outlet pipe of an air cleaner, and an intake flow rate is measured based on a flow rate of intake air passing through the flow meter.

The flow velocity of the intake air in the intake passage is:
Even under the condition that the intake air flow rate is constant, there is a possibility that the air flow partially or temporally fluctuates due to turbulence such as a vortex generated in the intake air flow or a separated flow. Particularly in an air cleaner, the intake air flow is likely to be disturbed by passing through a cleaner element or colliding with a corner of a cleaner case. Also, if the flow path from the inlet pipe to the outlet pipe is bent, the flow velocity distribution tends to be biased. Such fluctuations in the flow velocity tend to be more pronounced when the intake flow rate is small.
If the flow rate of the intake air fluctuates irrespective of the change in the intake air flow, a measurement error of the intake air flow will increase, which may lead to instability of the engine operating state, particularly the idling operating state.

In the flow measuring device described in Japanese Patent Application Laid-Open No. Hei 8-28559, a rectifying grid is arranged upstream of a flow meter, and the intake air flowing through the intake passage passes through the rectifying grid, so that the intake air flows. The turbulence of the intake air is eliminated, and the flow velocity of the intake air passing through the flow meter is made uniform to measure the intake air flow with high accuracy.

[0005]

If the grid spacing of the rectifying grid is larger than the vortex generated in the intake passage, the vortex passes without contacting the grid frame, so that the vortex is extinguished. You will not be able to do it. In order to reduce the turbulence of the intake air flow by the rectifying grid, it is necessary to increase the number of grids of the rectifying grid by setting the grid interval sufficiently small.

However, if the grid spacing is set small and the number of grids is increased, the portion of the intake air that comes into contact with the rectifying grid when passing through the rectifying grid, that is, the total area of the inner wall portion in each grid frame increases. , Ventilation resistance (friction resistance)
And the pressure loss increases.

An object of the present invention is to provide a flow rate measuring device and an air cleaner for reducing a pressure loss and measuring a gas flow rate with high accuracy.

[0008]

According to the first aspect of the present invention, the gas flow restricted by the restriction passage passes through the flow meter. In the narrowed gas flow, most of the turbulence disappears due to the increase in the flow velocity of the gas flow, so that the flow velocity fluctuation of the gas flow passing through the flow meter is reduced. Furthermore, since the turbulence is eliminated by the throttle passage, the ventilation resistance is reduced as compared with the conventional configuration using the rectifying grid.

A throttle member forming a throttle passage in the fluid passage is provided on the upstream side of the flow meter, and the position of the throttle member is adjusted so that gas having a high flow velocity collides with the throttle member. The gas flow with the highest turbulence in the gas flow collides with the inlet-side end face of the throttle member, and is narrowed into the throttle passage while reducing the turbulence. Do not pass through the meter.

The turbulence in the gas flow that has passed through the throttle passage is reduced and the flow velocity distribution is made uniform, so that the gas flow rate can be measured with high accuracy by the flow meter.

Further, the inner peripheral shape in the cross section of the throttle member facing the throttle passage forms a substantially rectangular shape or a part of the substantially rectangular shape, and the flow meter is parallel to the long side of the rectangle in the gas flow passing through the throttle passage. It is arranged in. By rectifying the fluid at the long side along the insertion direction of the flow meter, the gas is directed from the same direction to the flow meter in the fluid passage. Since the flow rate of the gas flowing through the flow meter has little fluctuation, the flow rate of the fluid can be measured with high accuracy by the flow meter.

According to the flow rate measuring device of the second aspect of the present invention, the inner peripheral shape of the throttle member is formed substantially U-shaped, and the flow meter is inserted into the fluid passage from the opening side in the cross section of the throttle member. Have been. Since the rectified fluid passing through the throttle passage passes through the entire flow meter provided in the fluid passage, the flow rate of the fluid can be measured with high accuracy by the flow meter.

According to the air cleaner of the third aspect of the present invention, the intake air flow narrowed by the throttle passage passes through the flow meter. In this narrowed intake flow, most of the turbulence disappears due to an increase in the flow velocity of the intake flow, so that the flow velocity fluctuation of the intake flow passing through the flow meter is reduced. Furthermore, since the turbulence is eliminated by the throttle passage, the ventilation resistance is reduced as compared with the conventional configuration using the rectifying grid.

A throttle member forming a throttle passage in the fluid passage is provided on the upstream side of the flow meter, and the position of the throttle member is adjusted so that high-speed intake air collides with the throttle member. In the intake flow, the flow with the highest turbulence, which has the highest turbulence, collides with the inlet-side end face of the throttle member, and the turbulence is reduced into the throttle passage while reducing the turbulence. Do not pass through the meter.

Since the turbulence in the intake air flow that has passed through the throttle passage is reduced and the flow velocity distribution is made uniform, the flow rate of the fluid can be measured with high accuracy by the flow meter.

Further, the inner peripheral shape in the cross section of the throttle member facing the throttle passage forms a substantially rectangular shape or a part of the substantially rectangular shape, and the flow meter is parallel to the long side of the rectangle in the intake air flow passing through the throttle passage. It is arranged in. The intake air is rectified along the long side along the insertion direction of the flow meter, so that the intake air flows from the same direction to the flow meter in the intake passage. Since the flow rate of the intake air flowing through the flow meter has little fluctuation, the flow rate of the intake air can be measured with high accuracy by the flow meter.

According to the air cleaner of the fourth aspect of the present invention, the inner peripheral shape of the throttle member is substantially U-shaped, and the flow meter is inserted into the intake passage from the opening side in the cross section of the throttle member. I have. Since the rectified intake air that has passed through the throttle passage passes through the entire flow meter provided in the intake passage, the flow rate of the intake air can be measured with high accuracy.

According to the air cleaner according to the fifth aspect of the present invention, the intake air flowing from the inlet pipe collides with the case wall opposite to the case wall to which the inlet pipe is attached, and separates from the colliding case wall to the outlet pipe. Heading. Therefore,
The direction of the intake flow is reversed, and the flow velocity distribution of the intake flow tends to vary. Even in such an air cleaner, the intake flow rate can be measured with high accuracy.

In a configuration in which the inlet pipe and the outlet pipe are not on the same axis and the flow velocity distribution of the intake flow toward the outlet pipe is apt to be deviated, the trajectory of the main flow of the intake flow on an imaginary plane parallel to the inlet-side end face of the throttle member. Is projected, with respect to an imaginary axis having the flow direction of the main flow of the intake flow as the positive direction, in the range of 60 ° in the clockwise direction and the counterclockwise direction from the positive side to the negative side with respect to the axis of the throttle member as the center. Fast flow velocity distribution,
That is, there is a distribution in which a large amount of turbulence is included in the intake flow.
According to the air cleaner described in claim 6 of the present invention, the throttle member opens in a range of less than 120 ° in the clockwise direction and the counterclockwise direction from the negative side to the positive side on the virtual axis. In other words, the opening of the throttle member is open in a range outside the distribution range of the intake flow having a high flow velocity. Therefore, the intake flow having a high flow velocity collides with the throttle member without directly passing through the flow meter, and passes through the flow meter after the turbulence is reduced, so that the intake flow rate can be measured with high accuracy.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIGS. 1 and 2 show an air cleaner according to a first embodiment of the present invention. A flow meter 20 is attached to the air cleaner 10.

As shown in FIGS. 1 and 2, a cleaner case 11 of the air cleaner 10 has a case 12 and a cap 13 formed of resin. An inlet pipe 14 is connected to the case 12, and an outlet pipe 15 is connected to the cap 13.
Is connected. The case 12 and the cap 13 are detachable, and the cleaner element 16 is accommodated in the case 12. The cleaner case 11 is formed in a substantially rectangular parallelepiped shape by six case walls. Case wall 11 which is one of four case walls surrounding filter element 16
a is connected to the inlet pipe 14, and is opposite to the inlet pipe 14 with the filter element 16 interposed between the case wall 11 b which is one of two case walls adjacent to the case wall 11 a among the four case walls surrounding the filter element 16. The outlet pipe 15 is connected to the side.

The inlet pipe 14 and the outlet pipe 15 are respectively connected to the case 12 and the cap 13 so as to be orthogonal to each other, and are not connected on the same axis. Outlet pipe 15
Is installed from the inlet pipe 14 to the cleaner case 11.
It is out of the way of the extension of the intake airflow flowing into. Outlet pipe 1
5 is formed in a funnel shape whose diameter increases toward the downstream side.

The flow meter 20 is a thermal flow meter, and the outlet pipe 1
5 has a circuit portion 21 attached to the outer wall, and a heating resistor 22 and a temperature-sensitive resistor 23 inserted into the intake passage 30 in the outlet pipe 15 together with the arm portion. Heating resistor 2
Reference numeral 2 indicates that the resistance value changes according to the flow velocity of the intake air flow, and the temperature-sensitive resistor 23 heats the heating resistor 22. The circuit unit 21 outputs a detection signal corresponding to the mass flow rate of the intake air, that is, the intake air flow rate, based on the current value supplied to the heating resistor 22. An engine control device (ECU) (not shown) determines a fuel injection amount based on a detection signal from each sensor including the intake flow rate.

A throttle plate 24 as a throttle member is provided with a flow meter 20.
It is arranged on the upstream side. The above-mentioned flow meter 20 and throttle plate 24 constitute a flow measuring device. The aperture plate 24 is formed in a substantially disk shape by a resin material or the like.
The outer peripheral portion is fixed to the inner peripheral wall of the outlet pipe 15 so as to be substantially perpendicular to the axial direction of the outlet pipe 15, that is, the flow direction of the suction air. As shown in FIG.
The inner peripheral wall 4 is formed in a substantially U-shape in cross section, and the substantially U-shaped inner peripheral wall and the inner peripheral wall of the outlet pipe 15 form a substantially rectangular throttle passage 31.

When the intake air flowing through the cleaner case 11 passes through the throttle passage 31, a contraction flow due to the intake air is formed downstream thereof. During this contraction, the flow velocity temporarily increases with a decrease in pressure. Therefore, even if a turbulence such as a vortex or a separation flow occurs in the intake flow at the upstream portion of the throttle passage 31, most of the turbulence is generated. Disappears during the contraction. Therefore, the contracted flow is a stable flow with little fluctuation in flow velocity, in other words, small fluctuation in pressure. The two resistors of the flow meter 20 are disposed during the contraction.

Next, the direction of the flow of intake air and the mounting angle of the throttle plate 24 will be described. The intake air flowing into the cleaner case 11 from the inlet pipe 14 is supplied to the case wall 11a facing the case wall 11a to which the inlet pipe 14 is attached.
Collide with c. The intake air that has collided with the case wall 11c passes through the filter element 16 and proceeds obliquely upward in FIG. 1 toward the outlet pipe 15 while leaving the case wall 11c.

A turbulence 101 such as a vortex or a separation flow is generated in the intake air flow which has collided with the case wall 11c and passed through the filter element 16. Assuming that the main flow 100 of the intake flow is projected on a virtual plane parallel to the inlet-side end surface 24a of the restrictor plate 24 and the flow direction of the main flow 100 of the intake flow is the positive direction, the axis of the restrictor plate 24 is centered. In the range of 0 ° ≦ θ1 ≦ 60 ° in the clockwise and counterclockwise directions from the positive side to the negative side of the virtual axis 110, there is an intake flow 102 having a high flow velocity in the flow velocity distribution of the intake flow.

When the inner peripheral wall of the throttle plate 24 having a U-shaped inner peripheral shape is opened in the range of the intake flow 102 having the high flow velocity, the intake flow having a high flow velocity and large turbulence passes directly near the two resistors. Therefore, as shown in FIG. 3, the fluctuation of the detection signal sent from the flow meter 20 to the ECU becomes large. FIG.
The angle of the throttle plate 24 is determined when the negative side of the insertion axis 111 of the flow meter 20 with the insertion direction of the flow meter 20 centered on the axis of the throttle plate 24 coincides with the positive side of the virtual axis 110, that is, the throttle When the opening in the cross section of the plate 24 faces the intake flow 102 having a high flow velocity, it is defined as 0 °. As can be seen from FIG. 3, the inner peripheral wall of the diaphragm plate 24 in the range of 0 ° ≦ θ2 <120 ° clockwise and counterclockwise from the negative side to the positive side of the imaginary axis 110 about the axis of the diaphragm plate 24. Is opened, the high-velocity intake air flow 102 collides with one of the inlet-side end faces 24a of the throttle plate 24, and the high-velocity intake air flow 102 flows toward the throttle passage 31.
Are narrowed down, so that the flow velocity is effectively made uniform. Thus, the fluctuation of the detection signal detected by the flow meter 20 is reduced, and the intake air flow rate can be measured with high accuracy.

In the first embodiment, since the flow meter 20 is disposed during the contraction, the flow rate fluctuation of the intake air passing through the flow meter 20 is reduced. It is possible to suppress the detection signal from fluctuating independently of the change in the intake air flow rate.

When the intake air passes through the throttle passage 31, the portion that comes into contact with the throttle passage 31 is limited to the outlet pipe 15 and the inner peripheral wall of the throttle plate 24. Very small compared to. Therefore, the pressure loss can be reduced as compared with the case where the rectifying grid is used.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
Shown in The same reference numerals are given to the same components as those in the first embodiment, and the description is omitted.

The throttle plate 35 forms a rectangular throttle passage 31 and has an arcuate intake passage 36 on both radially outer sides.
Is formed. As a result, the passage area formed by the throttle plate 35 is increased as compared with the first embodiment. The rotational position of the throttle passage 31 is in the same range as in the first embodiment. Therefore, it is possible to reduce the turbulence by causing the intake flow having a high flow velocity to collide with the throttle plate 35 and reduce the pressure loss when passing through the intake plate 35.

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention.
Shown in The same reference numerals are given to the same components as those in the first embodiment, and the description is omitted.

The inner peripheral shape of the diaphragm plate 40 is formed in a part of a substantially rectangular shape by two sides of a long side and a short side, that is, a substantially L-shape. Also in the third embodiment, since the intake flow having a high flow velocity collides with the throttle plate 40 and then flows into the throttle passage 41,
Disturbance of the intake flow is reduced, and the intake flow rate can be measured with high accuracy.

In the third embodiment, since the inner peripheral wall of the throttle plate 40 facing the throttle passage 41 is open in two directions, the angular range of the throttle plate 40 for reducing the output fluctuation of the flowmeter is the first embodiment. Narrower than.

In the above-described embodiments of the present invention, the turbulent intake air flow can be prevented from directly passing through the flow meter by colliding the intake air flow having a high flow velocity with the throttle plate. Therefore, the intake flow rate can be measured with high accuracy.

In the above embodiments, the flow rate measuring device installed in the air cleaner has been described. However, the present invention can be applied to any device for measuring the flow rate of gas.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view taken along line II of FIG. 2 showing an air cleaner according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view illustrating the air cleaner according to the first embodiment.

FIG. 3 is a characteristic diagram illustrating a relationship between an angle of a diaphragm plate and a fluctuation of a detection signal.

FIG. 4 is a cross-sectional view illustrating an air cleaner according to a second embodiment of the present invention.

FIG. 5 is a sectional view illustrating an air cleaner according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Air cleaner 11 Cleaner case 14 Inlet pipe 15 Outlet pipe 16 Cleaner element 20 Flow meter 24, 35, 40 Throttle plate 31, 41 Throttle passage

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinichi Kamiya 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation (72) Inventor Koichi Kaminaga 1, Toyota-cho, Toyota-shi, Aichi Prefecture Toyota Motor Corporation (72) Inventor Mitsumasa Yamagata 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Akira Iriyama 1-1-1 Toyota Town, Kariya City, Aichi Prefecture Toyota Boshoku Corporation F-term (reference) 2F035 AA02 EA04

Claims (6)

[Claims] 1. A flow meter for measuring a gas flow rate flowing through a fluid passage, and a throttle member disposed in the fluid passage upstream of the flow meter and forming a throttle passage for reducing a passage area of the fluid passage. An inner peripheral shape in a cross section of the throttle member facing the throttle passage forms an approximately rectangular shape or a part of an approximately rectangular shape with adjacent short sides and long sides, and the flowmeter Is disposed in parallel with the long side in the gas flow passing through the throttle passage,
The flow rate distribution device on the upstream side of the throttle member has a bias in the cross section of the fluid passage, and the throttle member is disposed at a position where a gas flow having a high flow velocity collides. 2. The flow meter according to claim 1, wherein an inner peripheral shape of the throttle member is substantially U-shaped, and the flow meter is inserted into the fluid passage from an opening side in a cross section of the throttle member. The flow measurement device as described. A cleaner case accommodating a filter element; an inlet pipe for introducing intake air to the cleaner case; and a cleaner case at a position deviating from an extension of an intake air flow introduced from the inlet to the cleaner case. An outlet pipe that is attached to discharge intake air from the cleaner case, a flow meter that is attached to the outlet pipe and measures an intake flow rate flowing through an intake passage, and that is disposed at the outlet pipe upstream of the flow meter, A throttle member that forms a throttle passage that reduces the passage area of the intake passage, wherein an inner peripheral shape in a cross section of the throttle member facing the throttle passage is substantially rectangular or substantially rectangular depending on adjacent short sides and long sides. Wherein the flow meter is disposed parallel to the long side in the intake air flow passing through the throttle passage,
An air cleaner characterized in that the flow velocity distribution on the upstream side of the throttle member is deviated in a cross section of the intake passage, and the throttle member is disposed at a position where an intake flow having a high flow velocity collides. 4. The throttle device according to claim 3, wherein an inner peripheral shape of the throttle member is substantially U-shaped, and the flow meter is inserted into the intake passage from an opening side in a cross section of the throttle member. The described air cleaner. 5. The cleaner case is formed in a substantially rectangular parallelepiped shape by six case walls, and the inlet pipe is connected to one of four case walls surrounding the filter element. 5. The outlet pipe is connected to one of two case walls adjacent to a case wall connecting the inlet pipe at a side opposite to the inlet pipe with the filter element interposed therebetween. The described air cleaner. 6. A trajectory of a main flow of an intake air flow projected on a virtual plane parallel to an inlet-side end face of the throttle member, and assuming a virtual axis having a main flow direction as a positive direction on the virtual plane, The aperture member such that the opening in the cross section of the aperture member faces in a range of less than 120 ° in a clockwise direction and a counterclockwise direction from the negative side to the positive side of the virtual axis about the axis of the member, respectively. 6. The air cleaner according to claim 5, wherein the rotational position of the air cleaner is set.