JP2003240614A - Flow measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress collision of dust included in the gas to be measured to a sensing part. <P>SOLUTION: This flow measuring device S1 is equipped with a bypass passage 21 for introducing and bypassing the gas from a passage where the gas flows, and a flow sensor 30 as the sensing part provided in the bypass passage 21, for measuring the flow rate of the gas. In the device S1, an adhesive member 40 as a collection member for collecting the dust K included in the gas is provided on the surface of a bending part 21c hit first by the gas at the inlet 21a of the bypass passage 21. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring device having a flow rate measuring sensing portion provided in a bypass flow path for introducing and bypassing a measurement gas from a flow path through which the measurement gas flows.

[0002]

2. Description of the Related Art This type of flow rate measuring device is attached to, for example, an air duct of an internal combustion engine as a flow path through which a gas to be measured flows, and the air in the air duct is bypassed, and the bypassed air flow rate is detected by a sensing section. taking measurement.

Here, as the sensing unit, for example,
An air flow sensor having a membrane structure in which a membrane is provided on a substrate and a metal heater and a thermometer are mainly arranged on the membrane is used.

[0004]

By the way, in the air measured by the flow rate measuring device, dust in the air is removed in advance by an air cleaner element or the like upstream. However, even after passing through the air cleaner element, minute dust such as sand is contained in the air. For example, when dust having a particle diameter of several hundreds of μm collides with the sensing unit, the sensing unit may be damaged.

In particular, in the flow rate measuring device using the air flow sensor having the above-mentioned membrane structure as a sensing portion, the membrane thickness of the sensor is about 1 μm, and it is easily damaged when the above dust collides.

In view of the above problems, an object of the present invention is to suppress the collision of dust contained in the gas to be measured with the sensing portion in the flow rate measuring device.

[0007]

According to the present invention, since the dust that damages the sensing portion has a large inertial force, when the flow of the gas to be measured is bent and diverted, it does not hit the wall surface of the flow path. Paying attention to the fact that the possibility of following the flow is extremely low, so when the dust hits the wall surface of the flow path,
This is done based on the idea that a means for collecting dust should be provided at the hit portion.

That is, according to the first aspect of the invention, the bypass channel (21) for introducing and bypassing the gas to be measured from the channel through which the gas to be measured flows and the gas to be measured provided in the bypass channel. Sensing unit for measuring flow rate (3
0) and a collecting member (40, 60) for collecting dust contained in the gas to be measured at a portion of the inlet (21a) of the bypass flow channel where the gas to be measured first hits. It is characterized by being provided.

According to this, at the inlet of the bypass flow path, which is the introduction portion of the gas to be measured, since the collecting member is provided at the portion where the gas to be measured first strikes, the dust contained in the gas to be measured is It is collected by the collecting member.

Therefore, it is possible to prevent the dust from reaching the sensing section, and as a result, it is possible to suppress the collision of the dust contained in the gas to be measured with the sensing section.

Here, the portion of the inlet of the bypass passage to which the gas to be measured first impinges can be set as in the invention described in claims 2 and 3.

That is, according to the second aspect of the present invention, a bent portion (21c) having a bent flow path is formed at the inlet (21a) of the bypass flow path (21). The portion where the measurement gas first strikes is characterized by being the inner wall surface of this curved portion. In this case, since the flow of the gas to be measured is diverted at the bend, the gas to be measured hits the inner wall surface of the bend.

Further, in the third aspect of the invention, the baffle member (50) which guides the gas to be measured into the bypass flow passage while blocking the flow of the gas to be measured is provided at the inlet (21a) of the bypass flow passage (21). ) Is provided, and the portion to which the gas to be measured first strikes is the surface of the baffle member. As the baffle member, specifically, a louver-like member can be used.

Further, in the invention as set forth in claim 4, the collecting member is provided with an adhesive member provided by being applied to a portion of the inlet (21a) of the bypass channel (21) to which the gas to be measured first impinges. (40).

According to this, the dust contained in the gas to be measured adheres to the adhesive member and is collected. Specifically, an adhesive, a gel, an emulsifier, a resin, or the like, which is applied in a liquid state and cured to form a film, can be used.

According to the invention of claim 5, such an adhesive member (40) is provided with a bypass flow passage (21).
If it is provided from the part of the inlet (21a) where the gas to be measured first impinges to the vicinity of the sensing part (30), the dust can be collected more reliably on the upstream side of the sensing part.

Further, as in the invention described in claim 6, as the collecting member (60), at the time of operation, a portion of the inlet (21a) of the bypass flow passage (21) to which the gas to be measured first impinges is operated. It is possible to employ a device that can apply static electricity and stop the application of static electricity when not in operation.

According to this method, static electricity is applied during operation to collect dust, and static electricity is stopped during non-operation to remove the collected dust, thus preventing clogging of the collection member. can do.

Further, in the invention described in claim 7, the bypass channel (21) for introducing and bypassing the measured gas from the channel through which the measured gas flows, and the measured gas provided in the bypass channel. In a flow rate measuring device including a sensing unit (30) for performing flow rate measurement, a portion having a repulsion coefficient smaller than that of a member forming the bypass flow passage is present in a portion of the bypass flow passage inlet (21a) where the gas to be measured first strikes. A restitution coefficient member (70) is provided.

According to this, the dust that flows in collides with the low restitution coefficient member to reduce the kinetic energy of the dust, and as a result, the dust easily flows along the normal flow of the bypass flow path, and the sensing is performed. The probability of dust colliding with the part is reduced. Therefore, it is possible to suppress the collision of the dust contained in the measured gas with the sensing unit.

Also in the case of this low coefficient of restitution member, the inlet (2) of the bypass flow passage (21) is provided as in the invention according to claim 8.
The inner wall surface of the bent portion (21c) formed in 1a) can be used as the portion on which the measured gas first strikes.

The reference numerals in parentheses of the above means are examples showing the correspondence with the concrete means described in the embodiments described later.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention shown in the drawings will be described. Although not limited to the use, in each of the following embodiments, the flow rate measuring device of the present invention, for example, is attached to an air duct as a flow path through which air as a gas to be measured flows in an intake system of an engine,
The description will be made assuming that the flow rate of the air flowing through the air duct is measured. In the following respective embodiments, the same parts are designated by the same reference numerals in the drawings.

(First Embodiment) FIG. 1 is a block diagram of a flow rate measuring apparatus S1 according to a first embodiment of the present invention, in which (a)
Is a schematic cross-sectional view, and (b) is an enlarged view of a schematic cross-section taken along the line AA in (a). Further, FIG. 1 shows a state in which the flow rate measuring device S1 is attached to the air duct 100, and the air duct 100 shows a part thereof.

This flow rate measuring device S1 has a case member formed of resin or the like as its main body.
As shown in (a), the flow path member 20 and the flow sensor 30 as a sensing unit are provided.

As shown in FIG. 1A, the flow rate measuring device S
No. 1 is attached with the flow path member 20 positioned inside the air duct 100 by inserting the flow path member 20 into the mounting hole 101 formed in the air duct 100. The mounting hole 101 is sealed by a sealing member (not shown) such as an O-ring.

Further, the flow rate measuring device S1 includes the flow path member 20.
And a circuit module (not shown) that is integrally provided. This circuit module is provided with a circuit for signal processing, a connector for electrically connecting to the outside, and the like. A wiring member such as a wire harness is connected to the connector, and is electrically connected to an engine control device (not shown) via the connecting member.

The air duct 100 is provided in the flow path member 20.
An inverted U-shaped bypass flow passage 21 is formed to introduce the air from and bypass it. Arrow Y in FIG. 1 (a)
As shown in FIG. 3, the air from the air duct 100 is introduced from the inlet 21 a of the bypass flow passage 21 and
It flows through the inside and again flows out from the outlet 21b of the bypass flow passage 21 to the air duct 100.

The flow path member 20 includes a bypass flow path 2
The flow sensor 30 that measures the flow rate of the air flowing through
The bypass passage 21 is installed so as to project into it.
The flow sensor 30 may be, for example, a flow sensor having a membrane structure that measures the air flow rate by utilizing the temperature-resistance characteristics of a heating resistor and a temperature sensitive resistor formed on the membrane.

The flow sensor 30 is fixed to a pedestal or the like (not shown), and the flow sensor 30 and the pedestal are wrapped with resin 23 in a form in which the detection area of the flow sensor 30 is exposed. Then, this resin mold body is fixed to the flow path member 20 by adhesion or the like. The flow sensor 30 is electrically connected to the signal processing circuit in the circuit module via a bonding wire or the like.

A rectifying member 24 for speeding up and stabilizing the flow of air around the flow sensor 30 is formed around the flow sensor 30 in the bypass passage 21. In the example shown in FIG. 1B, the rectifying member 24 is a throttle portion that protrudes from the inner wall surface of the bypass passage 21 in a convex curved shape.

In the flow rate measuring device S1, the signals of the heat-generating resistor and the temperature-sensitive resistor are detected by the flow sensor 30 exposed to the flow of the air to be measured.
The signal processing circuit or the like converts the signal into a signal corresponding to the air flow rate. Then, the converted signal is transmitted to the engine control device via the connector or the like.

In such a flow rate measuring device S1, in this embodiment, as shown in FIG.
A collecting member 40 that collects the dust K contained in the air is provided at a portion of the inlet 21a where the air first strikes.

In this embodiment, a bent portion (curved portion) 21c in which the flow path is bent is formed at the inlet 21a of the bypass flow path 21 and the air duct 100 is formed.
The portion where the air introduced from the first hits is the inner wall surface of the bent portion 21c. In this case, the air flow is deflected at the bent portion 21c, so that the air hits the inner wall surface of the bent portion 21c.

In this embodiment, the collecting member 40 is the adhesive member 40 provided by being applied to the inner wall surface of the curved portion 21c. Specifically, an adhesive, a gel, an emulsifier, a resin, or the like, which is applied in a liquid state and heat-cured or naturally dried to have a tackiness in a film state, can be used.

According to this, at the inlet 21a of the bypass flow passage 21 which is the air introduction portion of the air duct 100,
Since the adhesive member 40 as the collecting member is provided on the inner wall surface of the bent portion 21c, which is the portion to which the air first hits, the dust K contained in the air hits the wall surface without the bent portion 21c. When it does, it adheres to the adhesive member 40 and is collected.

Therefore, according to this embodiment, the dust K
Can be prevented from reaching the flow sensor 30, which is the sensing unit, and as a result, the collision of the dust K contained in the air with the flow sensor 30 can be suppressed. Then, it is possible to prevent the flow sensor 30 from being damaged.

In the present embodiment, the adhesive member 40 is provided not only on the inner wall surface of the bent portion 21c at the inlet 21a of the bypass flow passage 21 but also continuously from the inner wall surface to the vicinity of the flow sensor 30. It may be discontinuously provided on the inner wall surface of the bypass passage 21. According to it
The dust can be collected more reliably on the upstream side of the flow sensor 30.

(Second Embodiment) FIG. 2 is a schematic sectional configuration diagram of a flow rate measuring apparatus S2 according to a second embodiment of the present invention. At the inlet 21a of the bypass flow passage 21, the air duct 10
Bypassing the air while bypassing the flow of air of 0
A baffle member 50 that guides the inside of the device 1 is provided. As the baffle member 50, a louver is used in this example.

The baffle member 50 can prevent large dust in the air from entering the bypass passage 21. The surface of the baffle member 50 is a portion of the inlet 21a of the bypass flow passage 21 to which air first comes into contact, and in the present embodiment, an adhesive member similar to that in the first embodiment is a surface of the baffle member 50. It is provided by being applied to. The adhesive member is not shown in FIG.

The flow rate measuring device S2 of this embodiment as described above
Also in the same manner as in the first embodiment, the air duct 10
Inlet 21 of bypass flow passage 21 which is an air introduction part from 0
In a, since the adhesive member as the collecting member is provided on the surface of the baffle member 50, which is the portion that the air first hits, the dust contained in the air adheres to the adhesive member and is trapped. Gathered.

Therefore, according to the present embodiment, it is possible to prevent the dust from reaching the flow sensor 30, which is the sensing portion, and as a result, the collision of dust contained in the air with the flow sensor 30 is suppressed. be able to. Then, it is possible to prevent the flow sensor 30 from being damaged.

In this embodiment as well, as in the first embodiment, an adhesive member may be provided on the inner wall surface of the bent portion 21c.

(Third Embodiment) FIG. 3 is a block diagram of a flow rate measuring device S3 according to a third embodiment of the present invention, in which (a)
Is a schematic cross-sectional view, and (b) is an enlarged view of the wire netting 60 in (a) as seen from the direction of arrow B.

In this embodiment, the wire net 60 is provided at the inlet 21a of the bypass flow passage 21, and the air from the air duct 100 passes through the wire net 60 and enters the bypass flow passage 21. The wire net 60 is attached and fixed to the flow path member 20 by adhesion or the like. Therefore, the wire net 60 is a portion of the inlet 21 a of the bypass passage 21 to which air first comes into contact.

As shown in FIG. 3 (b), static electricity is generated in the wire net 60 by being energized by a power supply circuit 61 provided at an appropriate place. The timing of energizing the wire net 60 is such that the flow measuring device S3 is energized when it is in operation and is not energized when it is not in operation. Therefore, this wire mesh 60
However, it is configured as a collection member capable of applying static electricity during operation and stopping application of static electricity during non-operation.

According to this embodiment in which such a wire net 60 is used as a collecting member, static electricity is applied to the wire net 60 to collect dust during operation of the flow rate measuring device S3. In particular, dust containing silicon oxide (SiO ₂ ) or oil mist as a main component easily adheres to the wire netting 60 due to static electricity.

Therefore, in the present embodiment, the wire net 60, which is the portion of the bypass passage 21 to which the air first strikes, is configured as a collecting member, and is contained in the air when the flow rate measuring device S3 operates. The dust adheres to the wire net 60 and is collected. As a result, similarly to the above-described embodiment, it is possible to prevent dust from reaching the flow sensor 30, and it is possible to suppress the collision of dust contained in the air with the flow sensor 30.

Further, in the present embodiment, the flow rate measuring device S3
Since the collected dust can be released from the wire net 60 by stopping the application of static electricity to the wire net 60 during the non-operation, the clogging of the wire net 60 can be prevented.

The wire net 60 as the collecting member is
It may be provided on the inner wall surface of the bent portion 21c of the bypass flow passage 21 by adhesion or the like. In addition, the wire mesh 60 is provided with the baffle member 5 described above.
It may be provided on the front surface of 0 (surface on the upstream side) by adhesion or the like.

Furthermore, the adhesive member as shown in the first embodiment may be provided on the surface of the wire net 60. Also in the present embodiment, as in the first embodiment, an adhesive member may be provided on the inner wall surface of the bent portion 21c.

(Fourth Embodiment) In the fourth embodiment, in the flow rate measuring device S1 shown in FIG. 1 (b), the portion of the inlet 21a of the bypass passage 21 to which air is first applied, that is, the inner wall surface of the bent portion 21c. The collecting member 4
Instead of 0, a low coefficient of restitution member 70 having a coefficient of restitution smaller than that of the member forming the bypass passage 21 is provided.

The low coefficient of restitution member 70 has a coefficient of restitution of 80% or less, preferably 50% or less, with respect to the member forming the bypass flow passage 21, that is, the resin forming the flow passage member 20. Is.

The constituent member of the flow path member 20 is, for example, PBT.
Although (polybutylene terephthalate) is mixed with 30% of glass, the low restitution coefficient member 70 can be realized by changing the amount of mixed glass. Such a low restitution coefficient member 70 can be formed by a method such as two-color molding or attachment.

Here, the two-color molding means a molding method for producing an integrated product made of two colors or two kinds of resins. A dedicated machine equipped with two sets of injection devices is used for the molding. The main uses of two-color molded products are to insert letters, numbers, and symbols into calculators, computer keys, push-buttons for switches, knobs of machinery, etc.

As a typical example of the two-color molding process,
Mold the first color (first material) from the first cylinder, open the mold once, and while the primary molded product is attached to the core side, rotate the mold rotating disk 180 ° to close the mold, and then press the second cylinder. A second color (two materials) is molded, the mold is opened again, the molded product is taken out of the mold, and a two-color molded product is completed. This process uses two sets of dies, one for the primary molding and the other for the secondary molding. In actual operation, the two sets of injection devices operate almost at the same time, and one shot for every half rotation. Goods are obtained.

As another method, two sets of molds are attached back-to-back around a vertical axis and half-rotated about the vertical axis, or a pair of molds for primary molding and secondary molding are provided. There is a method of providing a cavity for molding and a set of cores. It is also possible to perform several-color molding (multicolor molding) by further developing the two-color molding method and increasing the number of cylinders.

As described above, by providing the low-repulsion coefficient member 70 on the inner wall surface of the bent portion 21c by two-color molding, pasting, or the like, the dust that flows in is reduced in the low-restitution coefficient member 70.
To reduce the kinetic energy of the dust. As a result, the dust easily flows along the wall surface of the bypass flow passage 21 along with the flow of air without repeatedly colliding with the inner wall of the bypass flow passage 21.

Therefore, according to this embodiment, it is possible to reduce the probability that the dust collides with the flow sensor 30. That is, the flow sensor 3 for dust contained in the air
The collision with 0 can be suppressed. Then, it is possible to prevent the flow sensor 30 from being damaged.

Also in the present embodiment, the low restitution coefficient member 70 is continuously provided not only on the inner wall surface of the bent portion 21c at the inlet 21a of the bypass passage 21 but also from the inner wall surface to the vicinity of the flow sensor 30. Alternatively or discontinuously, it may be provided on the inner wall surface of the bypass passage 21.

(Other Embodiments) The sensing unit is not limited to the flow sensor 30 having a membrane structure. Further, the application of the present invention is not limited to the measurement of the intake air flow rate.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a flow rate measuring device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a flow rate measuring device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a flow rate measuring device according to a third embodiment of the present invention.

[Explanation of symbols]

21 ... Bypass channel, 21a ... Inlet of bypass channel, 2
1c ... Bent portion of bypass flow passage, 30 ... Flow sensor,
40 ... Adhesive member, 50 ... Baffle member, 60 ... Wire mesh, 70
... Low coefficient of restitution member.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takao Ban             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F term (reference) 2F030 CC14 CF02 CF09                 2F035 AA02 EA03 EA08

Claims (8)

[Claims] 1. A bypass flow path (21) for introducing and bypassing the gas to be measured from a flow path of the gas to be measured.
And a sensing unit (30) provided in the bypass channel for measuring the flow rate of the gas to be measured, wherein a portion of the inlet (21a) of the bypass channel to which the gas to be measured first strikes The flow rate measuring device is characterized in that a collecting member (40, 60) for collecting dust contained in the gas to be measured is provided in the. 2. The inlet (21) of the bypass channel (21)
In a), a curved portion (21c) having a curved flow path is formed, and the portion to which the gas to be measured first impinges is the inner wall surface of this curved portion. The flow rate measuring device according to claim 1. 3. The inlet (21) of the bypass channel (21)
In a), a baffle member (50) for guiding the gas to be measured into the bypass channel while hindering the flow of the gas to be measured is provided, and a portion to which the gas to be measured first hits is an obstacle. The flow measuring device according to claim 1, wherein the flow measuring device is a surface of a member. 4. The collecting member is provided with the bypass channel (2).
4. The adhesive member (40) provided by applying the gas to be measured at the inlet (21a) of 1) to the portion to which the gas to be measured first strikes, the adhesive member (40) according to any one of claims 1 to 3. Flow measuring device. 5. The adhesive member (40) is provided from a portion of the inlet (21a) of the bypass flow passage (21), which is first contacted by the gas to be measured, to a vicinity of the sensing unit (30). The flow rate measuring device according to claim 4, characterized in that 6. The collecting member (60) applies static electricity to a portion of the inlet (21a) of the bypass flow passage (21) that is first exposed to the gas to be measured during operation, and static electricity when not operating. The flow rate measuring device according to any one of claims 1 to 3, wherein the application of the flow rate is stopped. 7. A bypass flow path (21) for introducing and bypassing the gas to be measured from a flow path of the gas to be measured.
And a sensing unit (30) provided in the bypass channel for measuring the flow rate of the gas to be measured, wherein a portion of the inlet (21a) of the bypass channel to which the gas to be measured first strikes Includes a low coefficient of restitution member (7) having a coefficient of restitution smaller than that of the member forming the bypass flow path.
0) is provided. 8. The inlet (21) of the bypass channel (21)
In a), a curved portion (21c) having a curved flow path is formed, and the portion to which the gas to be measured first impinges is the inner wall surface of this curved portion. The flow rate measuring device according to claim 7.