JP5984146B2 - Flow measuring device - Google Patents

Description

  The present invention is a flow rate measurement that is attached to a pipe for a vehicle or an industrial engine, takes a part of the fluid flowing in the pipe, and flows it on the flow rate measuring element to measure the flow rate of the fluid flowing in the pipe. It relates to the device.

  As a conventional flow rate measuring device, an inlet that opens toward the upstream side of a pipe, a vent hole that is located on the downstream side of the pipe, a channel that communicates the inlet and the vent, and a branch from the channel And a bypass passage having a bent portion in the middle, and a detection element is installed in the bypass passage. By providing such a configuration, it is possible to improve the fouling resistance and destruction resistance of the flow rate measuring element by preventing contaminants from flowing into the bypass flow path (see, for example, Patent Document 1).

Japanese Patent No. 4512499 (FIG. 1)

However, the prior art has the following problems.
In such a conventional flow rate measuring device, a part of the fluid to be measured taken into the flow rate measuring element flow path does not pass over the flow rate measuring element but is discharged together with the contaminants. For this reason, there has been a problem that the flow rate flowing through the flow path in which the flow rate measuring element is installed is reduced and the sensitivity of the flow rate measuring element is lowered.

  The present invention has been made in order to solve the above-described problems, and is capable of suppressing a decrease in sensitivity of the flow measuring element and improving the fouling resistance and destruction resistance of the detection element. The purpose is to obtain.

  A flow rate measuring device according to the present invention passes over a bypass flow channel that allows a part of a fluid to be measured flowing in a main flow channel to flow as a bypass fluid, a flow rate measuring element installed in the bypass flow channel, and the fluid measuring element. A flow measurement device comprising a flow measurement circuit for measuring a flow rate of a fluid to be measured from a result measured by a flow measurement element based on a fluid, wherein the bypass flow channel faces the upstream side in the flow direction of the main flow channel And an inlet that opens in a plane perpendicular to the flow direction and guides the bypass fluid into the bypass channel, an outlet that merges the bypass fluid that has passed through the bypass channel with the main channel, and an inlet and a flow One or more bends configured between the outlets and the fluid containing the contaminant so that the contaminant contained in the bypass fluid and having a higher density than the fluid to be measured does not pass over the fluid measuring element From fluid A branch flow path provided to flow in a branched manner, and the branch flow path is installed in a bent portion arranged upstream of the flow rate measuring element and contains a contaminant using inertia. In order to join the fluid containing the contaminants that have passed through the branch flow path and the bypass fluid to the bypass fluid, the side surface of the flow measuring element or the upstream side of the side surface and the contamination after joining And an outlet installed at a position where the fluid containing the object does not pass over the fluid measuring element.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to collect and flow a contaminant to a branch flow path, it can prevent that the fluid containing the contaminant which flows into a branch flow path flows on a flow measurement element. Furthermore, the flow rate passing through the bypass channel cross section in which the flow rate measuring element is installed can be made equal to the flow rate at the bypass channel inlet. As a result, it is possible to prevent a decrease in flow rate, and it is possible to realize a flow rate measurement device that can suppress a decrease in sensitivity of the flow rate measuring element and improve the stain resistance and destruction resistance of the detection element.

It is a schematic diagram which shows the installation state of the flow measuring apparatus in Embodiment 1 of this invention. It is a schematic diagram which shows the detail of the bypass flow path of the flow volume measuring apparatus in Embodiment 1 of this invention. It is AA sectional drawing of FIG. 2 in Embodiment 1 of this invention. It is BB sectional drawing of FIG. 3 in Embodiment 1 of this invention. It is a schematic diagram which shows the detail of the flow of the fluid in the bypass flow path in Embodiment 1 of this invention. It is a schematic diagram which shows the flow of the fluid around the 2nd bending part of the bypass flow path in Embodiment 1 of this invention. It is a schematic diagram which shows the positional relationship of the branch flow path outlet and flow volume measuring element in Embodiment 1 of this invention. It is a schematic diagram which shows the detail of the flow path structure of the branch flow path in Embodiment 2 of this invention. It is E sectional drawing of FIG. 8 in Embodiment 2 of this invention. FIG. 10 is a view corresponding to the E cross section of FIG. 8 for explaining the configuration of the branch flow path having a configuration different from that of FIG. 9; It is a schematic diagram which shows the detail of the bypass flow path of the flow volume measuring apparatus in Embodiment 3 of this invention.

  Hereinafter, preferred embodiments of a flow rate measuring device of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing an installation state of the flow rate measuring device according to Embodiment 1 of the present invention. A flow measuring device 1 shown in FIG. 1 is inserted into a pipe 2 and fixed by a flange 3. The flow rate measuring device 1 according to the first embodiment includes a flow rate measuring circuit 4 and a bypass flow path 5 having a branch flow path 10.

  A flow rate measuring element 6 is installed in the bypass channel 5. Furthermore, the bypass flow path 5 is opposed to the upstream side in the flow direction of the main flow 7, and bypass flow path inlet 8 that opens in a plane perpendicular to the flow direction, and in parallel with the flow direction of the main flow 7, A bypass channel outlet 9 is provided that opens in a plane perpendicular to the insertion direction.

  FIG. 2 is a schematic diagram showing details of the bypass flow path 5 of the flow rate measuring device 1 according to Embodiment 1 of the present invention. In the bypass channel 5, a first bent portion 11, a second bent portion 12, a third bent portion 13, a fourth bent portion 14, and a fifth bent portion 15 are formed. A part of the fluid to be measured flows into the bypass channel 5 from the bypass channel inlet 8, and is bypassed via the straight channel 28 formed between the second bent portion 12 and the third bent portion 13. It flows out from the channel outlet 9 and merges with the main flow 7.

  The flow rate measuring element 6 is installed in the straight flow path 28. A branch channel inlet 17 of the branch channel 10 is installed in the second bent portion 12 located upstream of the flow rate measuring element 6, and the straight channel 28 between the second bent portion 12 and the third bent portion 13 is provided. A branch channel outlet 18 is provided. The bypass channel cross section D on the downstream side of the second bent portion 12 and the branch channel inlet 17 are substantially orthogonal. The branch channel inlet 17 is disposed substantially perpendicular to the traveling direction of the fluid flowing into the second bent portion 12.

  In addition, the branch flow path 10 and the 2nd bending part 12 differ in the height in the paper depth direction, and are the flow paths which cross | intersect or run parallel in three dimensions. In FIG. 2, the branch flow path 10 is in the depth direction of the paper surface than the second bent portion 12.

  3 is a cross-sectional view taken along line AA of FIG. 2 in Embodiment 1 of the present invention. The branch channel 10 and the bypass channel 5 are connected by a branch channel opening 29 and a branch channel outlet 18 which is a similar opening.

  4 is a cross-sectional view taken along the line BB of FIG. 3 in the first embodiment of the present invention. The branch channel 32 in the vicinity of the branch channel outlet 18 has substantially the same shape and the same size as the branch channel outlet (opening) 18. Precisely, it is slightly larger (about several mm) than the branch channel outlet 18.

  Further, the flow of the branch flow path outlet 18 is made substantially parallel to the fluid flowing in the straight flow path 28 of the bypass flow path 5. For this reason, the flow of the fluid in the branch flow path 32 of the branch flow path outlet 18 and the flow of the fluid in the straight flow path 28 are substantially parallel.

  FIG. 5 is a schematic diagram showing details of the flow of the fluid in the bypass channel 5 according to Embodiment 1 of the present invention. The fluid 19 flowing into the second bent portion 12 is divided into a fluid 20 that goes straight as it is and flows into the branch flow channel inlet 17 and a fluid 21 that flows along the bend of the second bent portion 12. The straightly traveling fluid 20 flows into the branch channel 10 via the branch channel opening 29 and merges with the fluid 21 that flows into the bypass channel 5 at the branch channel outlet 18.

  The branch channel outlet 18 is located on the side surface of the flow rate measuring element 6 and on the upstream side of the flow rate measuring element 6, and is installed between the flow rate measuring element 6 and the channel wall surface 22 of the straight channel 28. Yes. Accordingly, the plane on which the flow rate measuring element 6 is projected and the plane on which the branch channel outlet 18 is projected on the cross section C in FIG. 2 (the cross section passing through the flow rate measuring element 6 perpendicular to the traveling direction of the fluid flowing in the straight flow path 28). The branch channel outlet 18 and the flow rate measuring element 6 are disposed at a position where the two do not intersect.

  In the fluid 19 entering the second bent portion 12, the contaminant having a density higher than that of the fluid to be measured cannot follow the change of the flow direction due to inertia and goes straight and flows through the branch channel 10 together with the fluid 20. The fluid 20 that has flowed into the branch channel 10 joins with the fluid 21 that has flowed into the bypass channel 5 at the branch channel outlet 18. Even if the fluid 20 joins the fluid 21, it does not pass over the flow rate measuring element 6 in order to maintain straightness.

  Accordingly, in the detection unit of the flow rate measuring element 6, it is possible to suppress an increase in accuracy error due to the adhesion of contaminants and a breakdown of the flow rate measurement function due to the impact of contaminant collision. That is, by realizing such a flow path configuration, it is possible to improve the fouling resistance and the destruction resistance. Further, the flow rate passing through the cross section C of the bypass flow path 5 in which the flow rate measuring element 6 is installed can be made equal to the flow rate passing through the bypass flow path inlet 8. For this reason, the fall of the sensitivity of the flow measuring element 6 can be suppressed.

  In the first embodiment, the straight flow path 28 between the bent portions of the second bent portion 12 and the third bent portion 13 is made to be a substantially straight line, whereby the fluid 21 shown in FIG. The straightness of the fluid flowing in the passage 5 is improved.

  The branch channel 32 in the vicinity of the branch channel outlet 18 has substantially the same shape and the same size as the branch channel outlet 18. Furthermore, the flow of the branch flow path outlet 18 is made substantially parallel to the fluid flowing in the straight flow path 28 of the bypass flow path 5. For this reason, the flow of the fluid in the branch flow path 32 of the branch flow path outlet 18 and the flow of the fluid in the straight flow path 28 are substantially parallel (precisely, the branch flow path 32 is the branch flow path. It is slightly larger (several millimeters) than the outlet 18). Therefore, the fluid 20 containing contaminants does not pass over the flow measuring element 6.

  FIG. 6 is a schematic diagram showing the flow of fluid around the second bent portion 12 of the bypass flow path 5 in Embodiment 1 of the present invention. The channel wall surface 22 is not bent in order to straighten the channel 26 in which the flow rate measuring element 6 is installed. The fluid 19 that enters the second bent portion 12 is divided into a fluid 20 that is directed toward the branch flow channel inlet 17 and a fluid 21 that is bent along the bend of the second bent portion 12.

  The fluid 21 that bends along the bend has an inertial force, and therefore peels off from the wall surface 22 toward the detection unit of the flow rate measuring element 6. Therefore, the pressure of the peeling part 26 falls below the pressure of the peripheral part, and the vortex 25 is generated. Since the vortex 25 is finally changed into heat, the vortex 25 becomes an energy loss with respect to the driving force that causes the fluid to flow through the bypass channel 5.

  In the first embodiment, the branch channel outlet 18 is installed in the vicinity of the peeling portion 26 in FIG. That is, the branch channel outlet 18 is located on the side surface of the wall surface 22 immediately after the second bent portion 12 and on the side surface and the upstream side of the flow rate measuring element 6. Such an installation position of the branch channel outlet 18 is a negative pressure region 26. For this reason, it has a function of attracting fluid to the branch flow path 10, and makes it easy for contaminants to flow into the branch flow path 10. In addition, the fluid 20 ′ flowing in the branch flow path flows in the negative pressure region 26, so that the strength of the vortex 25 is weakened.

  Therefore, energy loss in the flow path is reduced, and it is possible to suppress a decrease in the total flow rate, and a decrease in sensitivity of the flow rate measuring element 6 can be suppressed. The flow rate flowing through the branch channel 10 can be adjusted by the branch channel opening 29, the branch channel outlet 18, the channel cross-sectional area of the branch channel 10, and the like.

  When the flow rate flowing through the branch flow path 10 is large, a large amount of contaminants flows through the branch flow path 10. However, in this case, when the fluid 20 flowing out from the branch channel outlet 18 merges with the fluid 21 flowing in the bypass channel 5, it becomes easy to spread. Since the branch channel outlet 18 is installed on the side surface of the flow rate measuring element 6 or upstream of the side surface, if the spread is large, contaminants flow on the flow rate measuring element 6.

  On the other hand, when the flow rate flowing through the branch flow path 10 is small, particles having a high density that cause the flow measuring element 6 to break flow into the branch flow path 10 but adhere to the flow measurement element 6 and reduce the detection accuracy. Light contaminants will not flow into the branch channel 10. However, in this case, when the fluid 20 flowing out from the branch channel outlet 18 merges with the fluid 21 flowing into the bypass channel 5, the flow rate of the fluid 21 flowing through the bypass channel 5 is large, so that the contamination spreads. Is suppressed. Therefore, in consideration of these, it is necessary to adjust the flow rate flowing through the branch flow path 10 to an optimum amount.

  In the first embodiment, the branch channel opening 29 is rectangular, but may have a curved surface. FIG. 7 is a schematic diagram showing the positional relationship between the branch channel outlet 18 and the flow rate measuring element 6 in Embodiment 1 of the present invention, and is different from the previous FIG. In FIG. 7, the branch channel outlet 18 is installed upstream of the flow rate measuring element 6. Although an example was shown in FIG. 7, the position of the branch channel outlet 18 is in the case where a part of the branch channel outlet 18 is on the downstream side, the side surface and the upstream side in the positional relationship with the branch channel outlet 18. And all cases are considered upstream.

  As described above, according to the first embodiment, a configuration is provided in which a branch flow path is provided that can collect and flow contaminants and prevent the contaminants from flowing on the flow rate measuring element. Further, the flow rate passing through the bypass channel cross section in which the flow rate measuring element is installed is made equal to the flow rate at the bypass channel inlet. As a result, it is possible to prevent a decrease in flow rate, and it is possible to realize a flow rate measurement device that can suppress a decrease in sensitivity of the flow rate measuring element and improve the stain resistance and destruction resistance of the detection element.

Embodiment 2. FIG.
FIG. 8 is a schematic diagram showing details of the channel structure of the branch channel 10 according to Embodiment 2 of the present invention. By inserting the branch channel partition plate 30, the fluid 20 that has passed through the branch channel opening 29 is bent in a U shape, and then smoothly moves straight toward the branch channel outlet 18.

  FIG. 9 is a cross-sectional view taken along line E of FIG. 8 in the second embodiment of the present invention. When the fluid 20 flowing from the branch flow path opening 29 bends in a U shape and then advances straight toward the branch flow path outlet 18, the flow path height is smoothly changed.

  FIG. 10 is a view corresponding to the E cross section of FIG. 8 for explaining the structure of the branch flow path 10 having a structure different from that of FIG. The branch channel 10 shown in FIG. 10 does not change the channel height smoothly. The fluid flowing out from the branch flow path outlet 18 has a large flow component in the direction perpendicular to the flow direction of the bypass flow path 5, and the angle of collision with the wall surface 31 of the bypass flow path is nearly vertical.

  As a result, the fluid flowing out from the branch channel outlet 18 spreads when colliding with the wall surface of the bypass channel 5, and easily flows on the flow rate measuring element 6. For this reason, it is preferable that the structure shown in FIG. 9 is used, and the fluid flowing out from the branch channel outlet 18 is merged in parallel with the flow direction of the bypass channel 5 as much as possible.

  In order to suppress the spread at the time of merging, it is possible to increase the opening area of the branch channel outlet 18 to reduce the average flow velocity flowing through the opening 18 and to reduce the speed of collision with the wall surface 31 of the bypass channel. preferable.

  When expanding the opening area, it is necessary that the area where the flow rate measuring element 6 is projected on the cross section C of FIG. 2 and the plane where the branch flow path outlet 18 is projected do not intersect. For this reason, the branch channel outlet 18 has a shape in which the normal direction of the cross section C is long.

  As described above, according to the second embodiment, the structure having the partition plate as shown in FIG. 8 and the flow path when the fluid as shown in FIG. 9 goes straight toward the branch flow path outlet. It has a structure that changes the height smoothly. As a result, the spread of the fluid flowing through the branch flow path when joining the bypass flow path 5 can be suppressed. Therefore, fouling resistance and destruction resistance can be improved.

Embodiment 3 FIG.
FIG. 11 is a schematic diagram showing details of the bypass flow path 5 of the flow rate measuring device 1 according to Embodiment 3 of the present invention. The branch channel 10 is formed by installing the partition plate 27 between the first bent portion 11 and the third bent portion 13 (that is, in the vicinity of the second bent portion 12).

  In order to branch into the fluid 21 flowing through the bypass channel 5 and the fluid 20 flowing through the branch channel, a branch channel inlet 17 is installed in the first bent portion 11 upstream of the flow rate measuring element 6. The branch channel outlet 18 is installed on the upstream side of the flow rate measuring element 6, and the fluid 21 flowing in the bypass channel 5 and the fluid 20 flowing in the branch channel merge at the upstream side of the flow rate measuring element 6. .

  Contaminants having a density higher than that of the measurement fluid flowing in from the bias flow channel inlet 8 cannot follow the change of the flow direction due to inertia and go straight and flow through the branch flow channel 10. The fluid 20 flowing through the branch channel 10 merges with the fluid 21 that has flowed into the bypass channel 5 at the branch channel outlet 18.

  With respect to a vertical section C (a section perpendicular to the straight flow path 28 and passing through the flow measurement element 6) with the traveling direction of the fluid 21 flowing in the bypass flow path 5 as a normal line, the projection surface of the flow measurement element 6 and the branch flow The projection surface of the road outlet 18 does not intersect.

  The flow rate measuring element 6 is installed in the straight flow path 28 between the bent portions of the second bent portion 12 and the third bent portion 13. The branch channel 10 in the vicinity of the branch channel outlet 18 is substantially parallel to the bypass channel 5 (straight channel 28) between the bent portions.

  As described above, according to the third embodiment, the partition plate is provided between the bent portions, and the fluid is divided into the fluid that flows through the bypass channel and the fluid that flows through the branch channel. By providing such a configuration, it is possible to collect and flow contaminants in the branch channel, and it is possible to prevent the fluid containing the contaminants flowing in the branch channel from flowing on the flow rate measuring element. Furthermore, the flow rate passing through the cross-section of the bypass flow path in which the flow rate measuring element is installed can be made equal to the flow rate at the bypass flow path inlet. Accordingly, it is possible to suppress the deterioration of the sensitivity of the flow rate measuring element and improve the stain resistance and the breakdown resistance.

  DESCRIPTION OF SYMBOLS 1 Flow measuring device, 2 piping, 3 flange, 4 flow measuring circuit, 5 bypass flow path, 6 flow measuring element, 7 main flow, 8 bypass flow path inlet, 9 bypass flow path outlet, 10 branch flow path, 11th 1 bent portion, 12 second bent portion, 13 third bent portion, 14 fourth bent portion, 15 fifth bent portion, 17 branch channel inlet, 18 branch channel outlet (opening), 19 fluid (first) 2 fluid (flowing into the bent portion 12), 20 fluid (fluid flowing through the branch channel), 21 fluid (fluid flowing into the bypass channel at the bent portion 2), 22 flow channel wall surface (straight channel 28), 24 fluid (flow rate measurement) (Fluid flowing over the element), 25 vortex, 26 negative pressure region, 27 partition plate, 28 straight flow channel, 29 branch flow channel opening, 30 branch flow channel partition plate, 31 wall surface of bypass flow channel, 32 branch flow channel ( Near the branch channel outlet 18).

Claims (5)

A bypass flow path for flowing a part of the fluid to be measured flowing in the main flow path as a bypass fluid;
A flow rate measuring element installed in the bypass channel;
A flow measurement device comprising: a flow measurement circuit for measuring a flow rate of the fluid to be measured based on a result of measurement by the flow measurement device based on a fluid passing over the fluid measurement device;
The bypass flow path is
An inlet that opposes the upstream side in the flow direction of the main channel, opens in a plane perpendicular to the flow direction, and guides the bypass fluid into the bypass channel;
An outlet that merges the bypass fluid that has passed through the bypass channel into the main channel;
One or more bends configured between the inlet and the outlet;
Provided to branch off the fluid containing the contaminant from the bypass fluid so that the contaminant contained in the bypass fluid and having a density higher than that of the fluid to be measured does not pass over the fluid measurement element. A branch flow path, and
The branch channel is
An inlet that is installed in a bent portion disposed upstream of the flow rate measuring element and guides the fluid containing the contaminants to the branch channel using inertia;
In order to join the fluid containing the contaminants that have passed through the branch flow path to the bypass fluid, a fluid that is upstream of the side surface or the side surface of the flow rate measuring element and that contains the contaminants after joining. A flow rate measuring device comprising: an outlet installed at a position not passing over the fluid measuring element. The flow measurement device according to claim 1,
The outlet of the branch flow path is normal to the traveling direction of the bypass fluid flowing in the bypass flow path so that the fluid containing the contaminants after the merged flow does not pass over the fluid measuring element. The flow rate measuring device is installed at a position where the projection surface of the flow rate measuring element and the projection surface of the outlet of the branch channel do not intersect with respect to the vertical cross section. The flow rate measuring device according to claim 1 or 2,
The one or more bent portions are composed of two or more,
The flow rate measuring element is installed between two bent portions,
The bypass flow path between the two bent portions is formed as a straight flow path. The flow rate measuring device according to claim 3,
The outlet of the branch flow path is formed so that a flow path of the fluid containing the contaminants after joining is parallel to the DC flow path. In the flow measurement device according to any one of claims 1 to 4,
The flow rate measuring device, wherein the outlet of the branch channel is installed immediately after the bent portion disposed upstream of the flow rate measuring element.

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