JP6927342B2 - Air flow measuring device - Google Patents

Description

The present invention relates to an air flow rate measuring device that is attached to a duct through which intake air sucked into an internal combustion engine flows and measures the flow rate of the intake air.

Conventionally, as an air flow rate measuring device for measuring the flow rate of intake air of an internal combustion engine, a mounted portion attached to a duct and a vertically extending portion from the mounted portion protruding into the duct and detecting the flow rate of intake air. It has been proposed to include a housing for accommodating the sensor.
In recent years, from the viewpoint of improving the measurement accuracy of the flow rate, a sensor chip in which a thin-film resistor is formed on the surface of a semiconductor substrate has been studied as a sensor.
By the way, foreign matter such as dust that cannot be removed by the air cleaner may be mixed in the intake air. Then, when a foreign substance collides with the sensor chip, the resistor may be damaged.

Therefore, in the air flow rate measuring device, a housing having the following main bypass and sub-bypass is considered.
That is, the main bypass is a passage that takes in the intake air from the inside of the duct and discharges the intake air to the inside of the duct again. The sub-bypass is a passage that branches from the main bypass, takes in intake air from the main bypass, and joins the main bypass again. The sensor chip is housed in the sub-bypass (see, for example, Patent Document 1).
As a result, most of the foreign matter taken in together with the intake air from the intake port of the main bypass passes only through the main bypass without passing through the secondary bypass, and from the discharge port of the main bypass to the inside of the duct by inertial force. It is released.
However, in order to cope with the case where a foreign matter catching ability is adopted as an air cleaner or the vehicle is driven in an environment with a lot of dust, in the air flow rate measuring device, the foreign matter flowing into the sub-bypass from the main bypass is used. It is required to further reduce the amount of.

Japanese Unexamined Patent Publication No. 2004-012274

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the amount of foreign matter taken into the sub-bypass from the main bypass in an air flow rate measuring device including a main bypass and a sub-bypass. There is.

As a result of diligent examination, the applicant has adopted the following configuration, which makes it difficult for foreign matter contained in the intake air to be taken into the sub-bypass from the branch portion of the sub-bypass, and foreign matter to be taken into the sub-bypass from the main bypass. We found that the amount could be reduced.
The invention according to claim 1 is attached to a duct through which intake air sucked into an internal combustion engine flows, and a housing through which at least a part of the intake air passes, and passing air among the intake air passing through the inside of the housing. It is equipped with a sensor that detects the flow rate of the air.
The housing is branched from the main bypass, which has an intake port for taking in intake air and a discharge port for discharging passing air taken in from the intake port, and a sensor downstream from the intake port. It has a sub-bypass provided and a changing wall that changes the flow direction of the passing air taken in from the intake port on the upstream side of the branch portion of the sub-bypass from the main bypass.
Further, the intake port and the changing wall are provided in the housing so as to be aligned with each other in the flow direction of the intake air in the duct.
That is, according to the invention of claim 1, the intake port of the main bypass and the changing wall of the housing are provided in the housing so as to be aligned with each other in the flow direction of the intake air in the duct. Foreign matter taken in from the intake port together with air can collide with the changing wall. Therefore, since the kinetic energy of the foreign matter can be reduced by the collision, the foreign matter is less likely to be taken into the sub-bypass from the branch portion of the sub-bypass, and the amount of the foreign matter taken into the sub-bypass from the main bypass can be reduced. ..
Therefore, it is possible to suppress the collision and adhesion of foreign matter to the sensor.

It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 1). FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1 (Example 1). It is a cross-sectional view which expanded the part A of FIG. 1 (Example 1). FIG. 1 is a sectional view taken along line IV-IV of FIG. 1 (Example 1). It is sectional drawing which showed the air flow rate measuring apparatus (Example 2). It is sectional drawing which showed the air flow rate measuring apparatus (Example 3). It is an enlarged cross-sectional view of the change wall of the main bypass seen from the intake port (Example 4). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 5). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 6). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 7). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 8). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 9). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 10). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 11). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 12). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 13). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 14). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 15). It is sectional drawing which showed the air flow rate measuring apparatus attached to the duct (Example 16). (A) and (b) are cross-sectional views taken along the line XX-XX of FIG. 19 (Example 16). It is sectional drawing which showed the change wall of the main bypass seen from the intake port (variant example). (A) and (b) are cross-sectional views showing an air flow rate measuring device (modification example). (A) and (b) are cross-sectional views showing an air flow rate measuring device (modification example). (A) and (b) are cross-sectional views showing an air flow rate measuring device (modification example).

Hereinafter, modes for carrying out the invention will be described with reference to the drawings.

[Structure of Example 1]
1 to 4 show Example 1 to which the present invention is applied.

The air flow rate measuring device 1 is attached to a duct 2 through which the mainstream of intake air sucked into the internal combustion engine flows.
The air flow rate measuring device 1 includes the following attached portion 3 and the housing 4, and measures the flow rate of the intake air based on the detection result of the sensor 8.
The attached portion 3 has a flat attachment surface 5 necessary for attaching the air flow rate measuring device 1 to the duct 2. The attached portion 3 is arranged outside the duct 2. Further, the attached portion 3 is fastened and attached to the wall 6 of the duct 2 with screws 7. Then, the mounting surface 5 is pressed against the duct-side mounting surface provided on the outer surface of the wall 6 by fastening with screws 7. The mounting surface 5 is parallel to the direction of the intake air flow in the duct 2.

The housing 4 houses a sensor 8 that detects the flow rate of the intake air passing through the housing 4 (hereinafter, may be referred to as passing air AF) among the intake air. Further, the housing 4 is inserted into the inside of the duct 2 through the insertion hole 9 of the duct 2 and is arranged so as to protrude into the inside of the duct 2.
A fitting portion 10 that fits into the insertion hole 9 is provided between the mounted portion 3 and the housing 4. Further, for example, an O-ring is mounted between the outer peripheral surface of the fitting portion 10 and the inner wall of the insertion hole 9, and the airtightness of the duct 2 is maintained.
The housing 4 extends in a direction perpendicular to the mounting surface 5.

The housing 4 has the following main bypass 11 and sub bypass 12.
The main bypass 11 takes in the intake air from the inside of the duct 2 and discharges it into the inside of the duct 2 again. The main bypass 11 has an intake port 13 that takes in a part of the main stream of intake air, and a discharge port 14 that discharges the passing air AF taken in from the intake port 13.
The intake port 13 is open at the upstream end surface of the housing 4. The intake port 13 is open toward the upstream side of the intake passage 2a of the duct 2. Further, the intake port 13 is open near the center of the duct 2. The opening shape of the intake port 13 is square.
The discharge port 14 is open at the downstream end surface of the housing 4. The discharge port 14 is open toward the downstream side of the intake passage 2a.

Here, as shown in the figure, the direction of the flow of the intake air or the passing air AF flowing inside the duct 2 may be referred to as the x-axis direction.
Further, the direction perpendicular to the x-axis direction, that is, the direction in which the housing 4 protrudes into the duct 2 may be referred to as the y-axis direction.
Further, the direction perpendicular to the x-axis direction and the y-axis direction, that is, the direction perpendicular to the paper surface of FIG. 1 may be referred to as the z-axis direction.

The main bypass 11 has the following first and second bends 15 and 16.
The first bend 15 is a passage that first bends the direction of the flow of the passing air AF flowing in from the intake port 13 at the main bypass 11. The first bend 15 bends the flow direction of the passing air AF from the x-axis direction to the lower side shown in the y-axis direction.
The second bend 16 is a passage that bends the direction of the flow of the passing air AF on the downstream side of the first bend 15. The second bend 16 bends the flow direction of the passing air AF from the y-axis direction to the downstream side in the x-axis direction.
The main bypass 11 from the second bend 16 to the outlet 14 extends straight in the x-axis direction.
The angles of the first and second bends 15 and 16 are both 90 °.

The sub-bypass 12 takes in the passing air AF from the main bypass 11 and rejoins the main bypass 11. The sub-bypass 12 branches from the main bypass 11 downstream from the intake port 13 and is provided with a sensor 8.
The branch portion 21 of the sub-bypass 12 exists on the downstream side of the first and second bends 15 and 16.
The merging portion 22 of the sub-bypass 12 exists on the downstream side of the sensor 8.

The sub-bypass 12 has the following third bend 23.
The third bend 23 is a passage on the most upstream side in which the direction of the flow of the passing air AF flowing in from the branch portion 21 is first bent by the sub-bypass 12. The third bend 23 bends the flow direction of the passing air AF by 180 ° from the upper side shown in the y-axis direction to the lower side shown in the y-axis direction. That is, the third bend 23 has a U-turn structure.
As a result, most of the particulate foreign matter (hereinafter, may be referred to as dust D) taken in from the intake port 13 together with the intake air does not pass through the sub-bypass 12 but only the main bypass 11. It is discharged from the discharge port 14 to the inside of the duct 2 by inertial force.

The sensor 8 has a sensor support member 25 such as resin integrally molded on the sub-bypass wall 32 of the housing 4, and a sensor chip 26 held by the sensor support member 25.
The sensor chip 26 is housed in a sub-bypass 12 between the branch portion 21 and the third bend 23. The sensor chip 26 has a plurality of thin-film resistors on the surface of the semiconductor substrate, and employs a well-known thermal mass flow rate detection method that utilizes energization of these resistors. Further, the surface of the substrate of the sensor chip 26 is arranged so as to be parallel to the direction of the flow of the passing air AF flowing through the sub-bypass 12.

[Features of Example 1]
The housing 4 has a main bypass 11, a sub-bypass 12, a modified wall 31 and a sub-bypass wall 32.
The main bypass 11 has an inflow main passage 41 into which intake air flows in from the intake port 13, a change passage 42 extending along the change wall 31, and a common passage 43 extending from the change passage 42 toward the discharge port 14. ing.
The inflow main passage 41 is a first main passage from the intake port 13 to the first bend 15.
The change passage 42 is a second main passage from the first turn 15 to the second turn 16.
The common passage 43 is a third main passage from the second bend 16 to the discharge port 14.

The sub-bypass 12 has an inflow sub-passage 44 through which the passing air AF flows from the common passage 43, and an outflow sub-passage 45 through which the passing air AF flows out toward the common passage 43.
The inflow sub-passage 44 is a first sub-passage from the branch portion 21 to the third bend 23. A sensor 8 is provided in the inflow sub-passage 44.
The outflow sub-passage 45 is a second sub-passage from the third bend 23 to the merging portion 22. The outflow sub-passage 45 communicates with the inflow sub-passage 44 via the third bend 23.

The changing wall 31 changes the flow direction of the passing air AF taken in from the intake port 13 on the upstream side of the branch portion 21 of the sub-bypass 12 from the main bypass 11. The change wall 31 is provided before the sub-bypass 12 branches, that is, on the upstream side of the branch portion 21. Further, the changing wall 31 is an outer peripheral wall 33 of the first bend 15, and is a part of the passage wall of the changing passage 42.
The intake port 13 and the change wall 31 are provided in the housing 4 so as to be aligned with each other in the flow direction of the intake air in the duct 2.

The change wall 31 separates the change passage 42 and the inflow sub-passage 44 in a direction in which the inflow sub-passage 44 extends along the change passage 42.
The changing wall 31 has an intake port side surface 46 that is not orthogonal to the arrangement direction of the intake port 13 and the changing wall 31. As shown in FIG. 4, the intake port side surface 46 has an arcuate groove-shaped concave curved surface in which the cross section perpendicular to the flow axis at the first bend 15 projects convexly to the downstream side in the flow direction of the intake air. It is 46a.
The sub-bypass wall 32 separates the inflow sub-passage 44 and the outflow sub-passage 45 in a direction in which the outflow sub-passage 45 extends along the inflow sub-passage 44. The sub-bypass wall 32 extends along the change wall 31 on the opposite side of the change passage 42 with the inflow sub-passage 44 in between. Further, the sub-bypass wall 32 is a part of the passage wall of the inflow sub-passage 44 and the outflow sub-passage 45.

Further, the change passage 42 which is a part of the main bypass 11 from the first bend 15 to the branch portion 21 and the inflow sub-passage 44 which is a part of the sub-bypass 12 on the upstream side of the sensor chip 26 of the sensor 8 , The direction of flow in each forms an angle of 180 °.
That is, the direction of the flow of the passing air AF in the changing passage 42 is the direction from the upper side in the drawing to the lower side in the drawing in the y-axis direction. Further, the flow direction of the passing air AF in the inflow sub-passage 44 is a direction from the lower side in the drawing to the upper side in the drawing in the y-axis direction.
Therefore, the direction of the flow of the passing air AF in the changing passage 42 and the direction of the flow of the passing air AF in the inflow sub-passage 44 are 180 ° opposite directions.

[Effect of Example 1]
As described above, in the air flow rate measuring device 1 of the present embodiment, the housing 4 has an intake port 13 for taking in the intake air, and the passing air AF taken into the inflow main passage 41 from the intake port 13. It is provided with a changing wall 31 that changes the flow direction of the air.
The housing 4 is provided with the intake port 13 and the changing wall 31 so as to line up with respect to the flow direction of the intake air in the duct 2 in the housing 4.
As a result, the dust D taken in from the intake port 13 of the main bypass 11 together with the intake air can collide with the changing wall 31 of the housing 4 before the sub-bypass 12 branches. That is, the dust D can collide with the change wall 31 on the upstream side of the branch portion 21. Therefore, since the kinetic energy of the dust D can be reduced by the collision, the dust D is less likely to be taken into the sub-bypass 12 from the branch portion 21, and the amount of the dust D taken into the sub-bypass 12 from the main bypass 11 is further increased. It can be reduced.
Therefore, it is possible to suppress collision and adhesion of dust D to the sensor chip 26 of the sensor 8.

Further, the changing passage 42 of the main bypass 11 from the first bend 15 to the branch portion 21 and the inflow sub-passage 44 of the sub-bypass 12 on the upstream side of the sensor chip 26 have different directions of the passing air AF. Make an angle of 180 °.
As a result, the dust D cannot flow into the sub-bypass 12 unless the traveling direction is significantly changed in the branch portion 21, so that the dust D is more difficult to flow into the sub-bypass 12 from the branch portion 21. Therefore, the effect of suppressing the collision and adhesion of dust D with respect to the sensor chip 26 can be enhanced.
The improvement of the suppression effect due to the difference in the flow direction by 180 ° can be obtained particularly remarkably when the sensor chip 26 is arranged in the inflow sub-passage 44 on the upstream side of the third bend 23.

Further, the change wall 31 has an intake port side surface 46 that is not orthogonal to the arrangement direction of the intake port 13 and the change wall 31.
As a result, since the dust D is accelerated by the intake air, it collides with the concave curved surface 46a of the outer peripheral wall 33 of the first bend 15 and bounces off, and then collides with the concave curved surface 46a again. For this reason, the number of collisions of the dust D change wall 31 with the intake port side surface 46 increases, so that the kinetic energy of the dust D can be reliably deprived at a position relatively distant from the sensor chip 26 of the sensor 8. can.
Then, the dust D is less likely to be taken into the sub-bypass 12 from the branch portion 21, and the amount of dust D taken into the sub-bypass 12 from the main bypass 11 can be further reduced.
Therefore, it is possible to suppress collision and adhesion of dust D to the sensor chip 26 of the sensor 8.

[Example 2]
FIG. 5 shows Example 2 to which the present invention is applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.
The intake port side surface 46 of the change wall 31 has a V-groove shape in which the cross section perpendicular to the flow axis at the first bend 15 projects convexly to the downstream side in the flow direction of the intake air taken in from the intake port 13. It is an inclined surface 46b.

[Example 3]
FIG. 6 shows Example 3 to which the present invention is applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.
The intake port side surface 46 of the change wall 31 has a tapered groove shape in which the cross section perpendicular to the flow axis at the first bend 15 projects convexly to the downstream side in the flow direction of the intake air taken in from the intake port 13. It has an inclined surface 46c.

[Example 4]
FIG. 7 shows Example 4 to which the present invention is applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.

The change wall 31 has a recess 47 recessed toward the side opposite to the intake port 13 of the intake port side surface 46 of the change wall 31.
As a result, the dust D can be captured by the recess 47, so that the amount of dust D toward the branch portion 21 can be reduced.
Further, since the dust D collides with the recess 47 and the speed is further reduced, even if the dust D flows into the sub-bypass 12 from the branch portion 21, the dust D may collide with the sensor chip 26 of the sensor 8. Adhesion can be suppressed.

[Example 5]
FIG. 8 shows Example 5 to which the present invention is applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.

The change wall 31 projects toward the common passage 43 side from the sub-bypass wall 32.
As a result, the dust D is less likely to hit the wall surface 51 of the sub-bypass wall 32, so that the possibility of flowing into the sub-bypass 12 is greatly reduced, so that the amount of dust D flowing into the sub-bypass 12 can be reduced. ..

[Example 6]
FIG. 9 shows Example 6 to which the present invention is applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.

The sub-bypass wall 32 projects toward the common passage 43 side from the change wall 31.
As a result, the dust D hits the wall surface 51 of the sub-bypass wall 32, and the kinetic energy of the dust D is further reduced before flowing into the sub-bypass 12. That is, since the kinetic energy of the dust D is reduced by the collision immediately after the dust D flows into the sub-bypass 12, the dust D is located at a position sufficiently upstream of the sensor chip 26 of the sensor 8 in the sub-bypass 12. Kinetic energy can be reduced.
Further, when the intake air flows back in the duct 2 due to the pressure pulsation, the dust D may flow in from the discharge port 14. On the other hand, by adopting the above configuration, the dust D can be applied to the wall surface 52 of the sub-bypass wall 32 near the confluence portion 22, so that the kinetic energy of the dust D can be reduced. Therefore, collision and adhesion of dust D to the sensor chip 26 are suppressed even when the intake air flows back.

[Example 7]
FIG. 10 shows Example 7 to which the present invention is applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.

The sub-bypass 12 does not join the main bypass 11 and has a discharge port 53 different from the discharge port 14 of the main bypass 11.
The portion of the main bypass 11 on the downstream side of the branch portion 21 has a larger passage cross-sectional area than the sub-bypass 12. Therefore, of the main bypass 11, the portion downstream of the branch portion 21 has a smaller pressure loss than the sub bypass 12.
As a result, the flow rate of the passing air AF flowing into the sub-bypass 12 is reduced. Therefore, the amount of dust D flowing into the sub-bypass 12 can be reduced.

[Example 8]
FIG. 11 shows Example 8 to which the present invention is applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.

The sub-bypass 12 joins the main bypass 11.
The direction of the flow of the intake air of the discharge port 14 intersects the direction of the flow of the passing air AF taken in from the intake port 13.
As a result, the flow of the intake air discharged from the discharge port 14 and the flow of the intake air in the duct 2 collide at right angles, so that the discharge of the intake air from the discharge port 14 is suppressed. Therefore, since the intake of the intake air at the intake port 13 is suppressed, the inflow of dust D into the housing 4 can be suppressed.

[Example 9]
FIG. 12 shows Example 9 to which the present invention is applied. Here, the same reference numerals as those of Examples 1, 6 and 8 indicate the same configuration or function, and the description thereof will be omitted.

The discharge port 14 of the main bypass 11 opens at the lowermost side in the drawing in the y-axis direction of the housing 4.
Of the main bypass 11, the streamline of the flow of the passing air AF in the range from the second bend 16 to the discharge port 14 of the main bypass 11 is closer to the downstream side, the plane including the mounting surface 5 (hereinafter referred to as the reference plane B). It may be tilted away from). That is, the main bypass wall 34 of the main bypass 11 from the second bend 16 to the discharge port 14 is inclined toward the downstream side toward the side away from the common passage side end 35 of the sub-bypass wall 32.
As a result, the axis of the flow of the main bypass 11 can be inclined so as to be farther from the branch portion 21 toward the downstream side. Therefore, the dust D cannot flow into the sub-bypass 12 unless the traveling direction is significantly changed at the branch portion 21. Therefore, the effect of suppressing the collision and adhesion of dust D with respect to the sensor chip 26 can be enhanced.
The angle of the first bend 15 is 90 °, and the angle of the second bend 16 is 90 ° or more.

[Example 10]
FIG. 13 shows Example 10 to which the present invention is applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.

According to the air flow rate measuring device 1 of this embodiment, the sensor chip 26 is accommodated in the middle of the third bend 23.
Further, the sensor chip 26 may be accommodated in the sub-bypass 12 from the third bend 23 to the confluence portion 22 or the discharge port 53. Further, a passage extending in the x-axis direction may be provided in the middle of the third bend 23.

[Example 11]
FIG. 14 shows Example 11 to which the present invention is applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.

According to the air flow rate measuring device 1 of the present embodiment, the outer peripheral wall 33 of the first bend 15 includes a concave curved surface curved so as to bend from the x-axis direction to the y-axis direction.
As a result, the dust D turns along the axis of the flow at the first bend 15 while colliding with the outer peripheral wall 33 of the first bend 15. Therefore, since the number of collisions of the dust D with the changing wall 31 increases, the kinetic energy of the dust D can be further reduced before reaching the branch portion.
The shape of the outer peripheral wall of the second bend 16 may be a concave curved surface shape.

[Example 12]
FIG. 15 shows Example 12 to which the present invention is applied. Here, the same reference numerals as those of Examples 1 and 10 indicate the same configuration or function, and the description thereof will be omitted.

The sub-bypass 12 has a collision plate 54 extending in the direction of the flow of the passing air AF on the upstream side of the sensor chip 26 of the sensor 8.
As a result, the dust D receives the kinetic energy of the mainstream flow and is accelerated a little. Therefore, the dust D is mainly in a state where the kinetic energy is slightly increased in the sub-bypass 12 on the upstream side of the sensor chip 26 of the sensor 8. Even when taken into the sub-bypass 12 from the bypass 11, the speed is further reduced by colliding with the collision plate 54 in the sub-bypass 12, so that the kinetic energy of the dust D entering the sub-bypass 12 from the branch portion 21 is transferred. It can be reduced before reaching the sensor 8.

[Example 13]
FIG. 16 shows Example 13 to which the present invention is applied. Here, the same reference numerals as those of Examples 1 and 11 indicate the same configuration or function, and the description thereof will be omitted.
Similar to the twelfth embodiment, the sub-bypass 12 has a collision plate 54 extending in the direction of the flow of the passing air AF on the upstream side of the sensor chip 26 of the sensor 8.

[Example 14]
FIG. 17 shows Example 14 to which the present invention is applied. Here, the same reference numerals as those of Examples 1 and 10 indicate the same configuration or function, and the description thereof will be omitted.
The sub-bypass 12 has a third bend 23 that bends the direction of the flow of the passing air AF taken in from the main bypass 11 on the upstream side of the sensor chip 26 of the sensor 8.
The housing 4 has a plurality of recesses 55 in which the outer peripheral wall surface of the third bend 23 is recessed toward the outer peripheral side of the third bend 23.
As a result, the dust D receives the kinetic energy of the mainstream flow and is accelerated a little. Therefore, the dust D is mainly in a state where the kinetic energy is slightly increased in the sub-bypass 12 on the upstream side of the sensor chip 26 of the sensor 8. Even when the dust D is taken into the sub-bypass 12 from the bypass 11, the dust D collides with the recess 55 and the speed is further reduced. Therefore, the kinetic energy of the dust D entering the sub-bypass 12 from the branch portion 21 is detected by the sensor 8. It can be reduced just before reaching the sensor chip 26 of the above.

[Example 15]
FIG. 18 shows Example 15 to which the present invention is applied. Here, the same reference numerals as those of Examples 1 and 12 indicate the same configuration or function, and the description thereof will be omitted.
Similar to the 14th embodiment, the housing 4 has a plurality of recesses 55 in which the outer peripheral wall surface of the third bend 23 is recessed toward the outer peripheral side of the third bend 23.

[Example 16]
19 and 20 show Example 16 to which the present invention has been applied. Here, the same reference numerals as those in the first embodiment indicate the same configuration or function, and the description thereof will be omitted.

In the air flow rate measuring device 1 of this embodiment, the first bend 15 that bends the flow direction of the passing air AF from the x-axis direction to the z-axis direction is provided. Further, the air flow rate measuring device 1 is provided with a second bend 16 that bends the flow direction of the passing air AF from the z-axis direction to the x-axis direction.
As shown in FIG. 20A, the bending direction of the first bend 15 may be the lower side in the drawing from the x-axis direction to the z-axis direction. Further, the bending direction of the second bend 16 may be the downstream side in the x-axis direction from the z-axis direction as shown in FIG. 20 (a).
Further, as shown in FIG. 20B, the bending direction of the first bend 15 may be the upper side of the drawing from the x-axis direction to the z-axis direction. Further, as shown in FIG. 20B, the bending direction of the second bend 16 may be the downstream side in the x-axis direction from the z-axis direction.

[Modification example]
According to the air flow rate measuring device 1 of Examples 1 to 16, the present invention is applied to a device provided with a flat plate-shaped attached portion 3 which is fastened and attached to the wall 6 of the duct 2 by a screw 7. , As the present invention, it may be applied to the one provided with the attached portion 3 which is attached to the wall 6 by welding or adhesion.
In addition, welding means melting a part or all of the mounting surface 5 of the mounted portion 3 and fixing it to the wall 6.
Further, "adhesion" means fixing the mounting surface 5 of the mounted portion 3 to the wall 6 with an adhesive.

According to the air flow rate measuring device 1 of the first embodiment, the opening shape of the intake port 13 is square, but as in the modified example shown in FIG. 21, the opening shape of the intake port 13 is set to the y-axis. It may have an elliptical shape having a major axis in the direction and a minor axis in the z-axis direction.
Other examples of the opening shape of the intake port 13 include a circular shape, an oval shape, and a rectangular shape. Further, examples of the opening shapes of the discharge ports 14, 53, the branch portion 21, and the confluence portion 22 include a square shape, an elliptical shape, a circular shape, an oval shape, and a rectangular shape.
Further, the cross-sectional shapes of the passages of the main bypass 11 and the sub bypass 12 may be square, elliptical, circular, oval, or rectangular.

According to the air flow rate measuring device 1 of Examples 1 to 16, the shape of the outer wall 61 near the intake port 13 is a planar shape extending straight in the x-axis direction, but FIGS. 22 (a) and 22 (b) show. As in the modification shown in the above, the shape of the outer wall 61 in the vicinity of the intake port 13 may be gradually expanded to the outside of the housing 4 from the mouth edge of the intake port 13 toward the downstream side.
The modified example shown in FIG. 22A has a tapered surface on the outer wall 61 near the intake port 13.
On the other hand, the modified example shown in FIG. 22B has a convex curved surface on the outer wall 61 near the intake port 13.
As a result, the pressure loss of the flow of the intake air flowing inside the duct 2 can be reduced.
In FIGS. 22 (a) and 22 (b), the surface configuration of the suction port side surface of the modified wall 31 is a surface configuration having a concave curved surface 46a, but the surface configuration of the suction port side surface of the modified wall 31 is shown in FIG. A surface configuration having an inclined surface 4b as shown in 5 may be used. Further, the surface configuration of the suction port side surface of the modified wall 31 may be a surface configuration having an inclined surface 46c as shown in FIG.

According to the air flow rate measuring device 1 of Examples 1 to 16, the shape of the inner side wall 62 near the intake port 13 is a planar shape extending straight in the x-axis direction, but FIGS. 23 (a) and 23 (b) show. As in the modification shown in the above, even if the shape of the inner side wall 62 near the intake port 13 is gradually reduced from the mouth edge of the intake port 13 toward the downstream side, the passage cross-sectional area of the main bypass 11 is gradually reduced. good.
The modified example shown in FIG. 23A has a tapered surface on the inner side wall 62 near the intake port 13.
On the other hand, the modified example shown in FIG. 23B has a convex curved surface on the inner side wall 62 near the intake port 13.
As a result, the dust D collides with the inner side wall 62 near the intake port 13. Therefore, the kinetic energy of the dust D can be further reduced before reaching the branch portion.
In FIGS. 23 (a) and 23 (b), the surface configuration of the suction port side surface of the modified wall 31 is a surface configuration having a concave curved surface 46a, but the surface configuration of the suction port side surface of the modified wall 31 is shown in FIG. A surface configuration having an inclined surface 4b as shown in 5 may be used. Further, the surface configuration of the suction port side surface of the modified wall 31 may be a surface configuration having an inclined surface 46c as shown in FIG.

According to the air flow rate measuring device 1 of the first to third embodiments, the surface configuration of the intake port side surface of the changing wall 31 is changed to an arc groove-shaped concave curved surface 46a, a V-groove-shaped inclined surface 46b, or a tapered groove-shaped inclined surface. Although the surface configuration has 46c, as in the modified example shown in FIG. 24A, a surface configuration in which two semicircular groove-shaped concave curved surfaces 46d and one flat surface 46e may be combined may be used. Specifically, a surface configuration having a shape in which a plane 46e is sandwiched between two concave curved surfaces 46d may be used.
Further, as in the modified example shown in FIG. 24 (b), a semi-circular groove-shaped concave curved surface 47f may be used.
Thereby, the same actions and effects as in Examples 1 to 3 can be obtained.

According to the air flow rate measuring device 1 of Examples 1 to 16, the flow directions of a part of the main bypass 11 and a part of the sub-bypass 12 are configured to form an angle of 180 °. , A part of the main bypass 11 and a part of the sub-bypass 12 may be configured so that the flow directions in each of them form an angle larger than 180 °.
According to the air flow rate measuring device 1 of Examples 1 to 16, the number of bends of the main bypass 11 is two, that is, the first and second bends 15 and 16, and the number of bends of the sub bypass 12 is the third. Although it was one of the bends 23, the number of the main bypass 11 and the sub bypass 12 is not limited. That is, the number of bends of the main bypass 11 may be one or three or more, and the number of bends of the sub bypass 12 may be two or more.

In the air flow rate measuring device 1 of the first embodiment, the angles of the first bend 15 and the second bend 16 are 90 °, and in the air flow rate measuring device 1 of the ninth embodiment, as shown in FIG. The angle of the second bend 16 is 90 ° or more, but the angle of the bend is not limited to such an aspect.
That is, the angle of the first bend 15 may be an angle other than 90 °, and the angle of the second bend 16 may be less than 90 °.
In the air flow rate measuring device 1 of Examples 1 to 16, the angle of the third bend 23 is 180 °, but the angle of the third bend 23 may be an angle other than 180 °.

1 Air flow rate measuring device 2 Duct 4 Housing 8 Sensor 11 Main bypass 12 Sub bypass 13 Intake port 14 Outlet port 31 Change wall 46 Intake port side surface

Claims (10)

A mounted portion (3) having a mounting surface (5) mounted on a duct (2) through which intake air sucked into an internal combustion engine flows.
A housing (4) through which at least a part of the intake air passes, and
A sensor (8) for detecting the flow rate of passing air (AF) passing through the inside of the housing among the intake air is provided.
In the air flow rate measuring device (1) that measures the flow rate of the intake air based on the detection result of the sensor.
The housing is
A main bypass (11) having an intake port (13) for taking in the intake air and a discharge port (14) for discharging the passing air taken in from the intake port.
A sub-bypass (12), which is branched from the main bypass downstream of the intake port and is provided with the sensor,
The main bypass is provided on the downstream side of the intake port, and the direction in which the passing air taken in from the intake port flows is on the upstream side of the branch portion (21) of the sub bypass from the main bypass. With a change wall (31) that can be changed in
The intake port and the change wall are provided so as to line up along the mounting surface.
The change wall
It has intake port side surfaces (46a, 46b, 46c) provided at positions aligned with the intake port along the mounting surface.
The main bypass
A changing passage (42) provided between the intake port and the changing wall in the alignment direction and extending along the changing wall in an orthogonal direction orthogonal to the mounting surface.
Extending from said change passages downstream toward the discharge port, possess an inclined path which is inclined to the side away from the mounting surface toward the downstream side (43), a
The main bypass
A first bend (15) provided between the intake port and the change passage in the main bypass and bending the main bypass from the intake port toward the change passage.
A second bend (16) provided between the modified passage and the inclined passage in the main bypass and bending the main bypass from the modified passage toward the inclined passage is provided.
Of the forming surfaces forming the inclined passage, the surface opposite to the changing wall in the orthogonal direction via the inclined passage, and the downstream side is inclined toward the side away from the mounting surface. An air flow rate measuring device characterized in that the wall surface extends downstream from the second bend toward the discharge port. The housing is a surface of the forming surfaces forming the inclined passage, which is opposite to the changing wall via the inclined passage in the orthogonal direction, and is inclined toward the downstream side toward the side away from the mounting surface. The air flow rate measuring device according to claim 1, further comprising an inclined wall surface which is a surface. The downstream end of the sub-bypass is provided on the side opposite to the intake port via the main bypass in the alignment direction, and is released toward the side opposite to the mounting surface in the orthogonal direction. , The air flow rate measuring device according to claim 1. The air flow rate measuring device according to claim 1, wherein the inclined passage extends toward the downstream end of the sub-bypass in the alignment direction and is inclined with respect to the downstream end of the sub-bypass. The air flow rate measuring device according to any one of claims 1 to 4 , wherein the sub-bypass has a collision plate (54) extending along the direction of the flow of the passing air on the upstream side of the sensor. .. The sub-bypass has a bend (23) that bends the direction of the flow of the passing air taken in from the main bypass on the upstream side of the sensor.
The air flow rate measurement according to any one of claims 1 to 5 , wherein the housing has a plurality of recesses (55) in which the outer peripheral wall surface of the bend is recessed toward the outer peripheral side of the bend. Device. The modified wall is an outer peripheral wall (33) of a bend (15) that first bends the direction of the flow of the intake air flowing in from the intake port at the main bypass.
Claims 1 to 6 in which a part of the main bypass from the bend to the branch portion and a part of the sub-bypass on the upstream side of the sensor have a flow direction of 180 ° or more at each angle. The air flow rate measuring device according to any one of the above. The modified wall is a curved outer peripheral wall that first bends the direction of the flow of the intake air flowing in from the intake port at the main bypass.
Any one of claims 1 to 7 , wherein the modified wall has a plurality of recesses (47) in which the intake port side surface (46) of the modified wall is recessed toward the side opposite to the intake port. The air flow rate measuring device according to one. The sub-bypass does not merge with the main bypass and has an outlet (53) separate from the outlet of the main bypass.
The air flow rate measuring device according to any one of claims 1 to 8 , wherein the portion of the main bypass on the downstream side of the branch portion has a pressure loss smaller than that of the sub bypass. The air flow rate measuring device according to any one of claims 1 to 9, wherein the direction of the flow of the intake air at the discharge port intersects the direction of the flow of the intake air taken in from the intake port.

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