JP2012242298A - Flow rate detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve flow rate detection accuracy in a flow rate detection device where a flow rate sensor part is supported at both ends with respect to a flow passage.SOLUTION: A flow rate detection device (10) includes: a flow passage member (11) having a flow passage (11b); and a flow rate sensor part (12) which is partially arranged by projection toward the flow passage (11b) from the flow passage member (11) and is supported by the flow passage member (11) at both the ends. The flow rate sensor part (12) includes a sensor chip (20), a support member (30), and a projection part (40). The support member (30) includes a fixing part (31) and rectification parts (32) in the sensor chip (20). The projection part (40) is projected from the support member (30) and connected to the flow passage member (11) so as to divide the flow passage (11b) together with the support member (30). The thickness of the projection part (40) is thinner than a distance (D) between a flow rate detection part formation surface (21b) of the sensor chip (20) and a rear surface (31b) of the fixing part (31).

Description

  The present invention relates to a flow rate detection device that measures a flow rate of a fluid.

  For example, as shown in Patent Document 1, a flow rate detection device installed in a flow path has been proposed.

  This flow rate detection device includes a flow channel member (detection tube) for detecting a flow rate, and a flow rate sensor unit provided in the flow channel inside the flow channel member. The flow sensor unit includes a support member that protrudes from the inner wall surface of the flow path member to the flow path in a direction perpendicular to the flow of the fluid, and a thermal type that is incorporated on one surface of the support member so as to be exposed in the flow path. And a flow sensor.

  Further, the support member is arranged so as to equally divide the cross section perpendicular to the axis of the flow path into two, and is supported at both ends.

Japanese Patent No. 3404251

  By the way, the flow rate sensor portion that protrudes from the inner wall surface of the flow path member to the flow path may resonate due to external vibration, which may cause abnormal flow detection or breakage.

  As described above, in Patent Document 1, the support member (flow sensor unit) has a dual-support structure. When the double-sided support structure is used as described above, the resonance frequency of the flow sensor unit can be increased as compared with the case of the cantilevered support structure. Thereby, the resonance frequency can be made higher than the frequency band of external vibrations, and it is possible to make it difficult to cause abnormality in flow rate detection due to resonance and destruction of the flow rate detection device.

  However, in the flow rate detection device disclosed in Patent Document 1, the thickness of the portion excluding the widened portion, which is the portion on the tip side of the support portion (the portion on the tip side of the flow rate sensor) of the support member, It is substantially equal to the distance between the flow rate detection portion forming surface of the sensor and the back surface of the sensor mounting surface in the support member (built-in portion). For this reason, the proportion of the cross section perpendicular to the axis of the flow path occupied by the support member is larger than that in the cantilever support structure, and the support member may hinder the flow of fluid in the flow path. When the flow of fluid in the flow path is hindered, pressure loss occurs, resulting in a problem that the flow rate detection accuracy is lowered due to a decrease in flow rate sensitivity.

  In view of the above problems, an object of the present invention is to improve flow rate detection accuracy in a flow rate detection device in which a flow rate sensor unit is supported at both ends with respect to a flow path through which a fluid flows.

In order to achieve the above object, the invention described in claim 1
A flow path member (11) through which a fluid flows in an internal flow path (11b);
A part of the flow path member (11) is disposed so as to protrude from the inner wall surface of the flow path member (11) to the flow path (11b) and is supported at both ends by the flow path member (11) so as to be perpendicular to the fluid flow direction of the flow path (11b) A flow rate sensor device (12) for dividing a cross section,
The flow sensor unit (12)
On the one surface (21b) side of the substrate (21), a flow rate detector (22) having a heater resistor (23) and temperature measuring resistors (24u, 24d) positioned upstream and downstream of the heater resistor (23), respectively. ) And a sensor chip (20) in which the flow rate detection unit (22) is disposed in the flow path (11b),
In the direction perpendicular to the flow direction, it projects from the inner wall surface of the flow path member (11) to the flow path (11b), and in the thickness direction perpendicular to the projecting direction and the flow direction, the sensor chip (20) forms the flow rate detection unit. A fixed portion (31) fixed with the surface (21c) opposite to the surface (21b) as a mounting surface, and connected to the fixed portion (31) and opposed to the side surface of the sensor chip (20), and at least a flow rate detection A support member (30) comprising: an upstream rectification part (33) located upstream relative to the part (22); and a rectification part (32) having a downstream rectification part (34) located downstream. ,
A protrusion (40) that protrudes from the support member (30) and is connected to the flow path member (11) and divides the cross section perpendicular to the fluid flow direction of the flow path (11b) together with the support member (30). Have
In the thickness direction, the thickness of the protrusion (40) depends on the flow rate detection part forming surface (21b) of the sensor chip (20) and the back surface (31a) of the mounting surface (31a) of the sensor chip (20) in the fixing part (31). 31b), which is thinner than the distance (D).

  Thus, in the present invention, the protrusion (40) is thinner than the distance D. According to this, since the area occupied by the flow rate detection device in the cross section perpendicular to the flow direction of the fluid in the flow path (11b) can be made smaller than that in the conventional structure, the flow of the fluid is in the flow rate sensor unit (12). It becomes difficult to be inhibited by.

  Therefore, it is possible to suppress a decrease in flow rate detection accuracy caused by the flow inhibition.

As described in claim 2, the rectifying unit (32) faces the protruding front end surface (20e) perpendicular to the upstream side surface (20u) and the downstream side surface (20d) of the side surfaces of the sensor chip (20). It has a tip side rectification part (35) arranged,
The protrusion (40) is preferably configured to be connected to the tip-side rectifying part (35).

  According to this, the distance between the protrusion (40) and the sensor chip (20) is longer than that of the structure having no tip side rectification part (35). Therefore, the influence which the disturbance of the fluid resulting from the projection part (40) has on the sensor chip (20) can be suppressed. In addition, since the sensor chip (20) is surrounded on three sides by the rectification unit (32), the sensor chip (20) can be easily positioned with respect to the support member (30).

  As described in claim 3, the upstream end (40u) of the protrusion (40) is disposed downstream of the downstream temperature measuring resistor (24d) of the sensor chip (20) in the flow direction. A configuration is preferred.

  According to this, the turbulence of the flow due to the protrusion (40) is less likely to occur upstream of the downstream temperature measuring resistor (24d) of the sensor chip (20). Therefore, the influence which the disturbance of the fluid resulting from the projection part (40) has on the sensor chip (20) can be suppressed.

  In particular, as described in claim 4, the downstream end (40d) of the projection (40) is arranged flush with the downstream end (34d) of the support member (30). preferable.

  According to this, since the downstream end (40d) of the protrusion (40) and the downstream end (34d) of the support member (30) are flush with each other, the downstream end ( Compared to a structure in which there is a step between 40d) and the downstream end (34d) of the support member (30), it is possible to suppress turbulence in the flow that occurs when the fluid flows backward.

  As described in claim 5, in the thickness direction, the protrusion (40) is connected to the support member (30) on the back side of the flow rate detection part formation surface (21b) of the sensor chip (20). A configuration is preferred.

  According to this, the protrusion (40), which is one of the causes of fluid flow disturbance, is disposed at a position away from the flow rate detection part forming surface (21b) of the sensor chip (20). Therefore, the influence which the disturbance of the fluid resulting from the projection part (40) has on the sensor chip (20) can be suppressed.

  In particular, as described in claim 6, in the thickness direction, the protrusion (40) is relative to the surface (31b) opposite to the mounting surface (31a) of the sensor chip (20) in the fixing portion (31). A configuration in which they are arranged flush is preferable.

  According to this, since one surface of the protruding portion (40) is flush with the back surface (31b) of the fixing portion (31) in the support member (30), the protruding portion (40) has a flow rate of the sensor chip (20). The support member (30) including the protrusion (40) is simplified while suppressing the influence of the fluid disturbance on the sensor chip (20), being arranged at a position away from the detection part forming surface (21b). can do.

  As described in claim 7, the protrusion (40) is preferably formed using the same material as the support member (30).

  According to this, a projection part (40) can be integrally formed with a support member (30). Even when the manufacturing process is different, there is no difference in the linear expansion coefficient between the support member (30) and the protrusion (40), so that the thermal stress is applied to the temperature change around the flow rate sensor (12). Does not occur. Therefore, the connection reliability between the support member (30) and the protrusion (40) can be increased as compared with the case where the materials of the two are different.

  As described in claim 8, the protrusion (40) is preferably formed using a material having a Young's modulus larger than that of the support member (30).

  Thus, when a material having a Young's modulus greater than that of the support member (30) is used for the protrusion (40), the Young's modulus increases as a whole of the flow rate detection device. Here, the resonance frequency is proportional to the square root of Young's modulus. Therefore, compared with the structure which does not change the material of a protrusion part (40), the resonant frequency becomes large as the whole flow volume detection apparatus. For this reason, abnormalities in flow rate detection caused by resonance caused by vibrations received from the outside and destruction of the flow rate detection device are less likely to occur.

  As described in claim 9, the flow path member (11) has a recess (11c) on the inner wall surface, and the protrusion (40) is preferably bonded and fixed while being inserted and disposed in the recess (11c). .

  According to this, the manufacturing process can be simplified while stabilizing the both-end supported structure.

It is a fragmentary sectional view which shows schematic structure of the flow volume detection apparatus which concerns on 1st Embodiment. FIG. 2 is an enlarged view of the vicinity of a flow rate sensor unit in the flow rate detection device shown in FIG. 1. It is a figure which shows schematic structure of a sensor chip, (a) is a top view, (b) is sectional drawing which follows the IIIb-IIIb line | wire of (a). It is sectional drawing which follows the IV-IV line of FIG. It is sectional drawing which follows the VV line of FIG. It is a fragmentary sectional view which shows the modification of a flow sensor part. It is sectional drawing which follows the VII-VII line of FIG. It is the figure which expanded the flow sensor part periphery in the flow rate detection apparatus concerning a 2nd embodiment. It is a fragmentary sectional view which shows the modification of a flow sensor part. It is sectional drawing to which the flow sensor part periphery was expanded in the flow volume detection apparatus which concerns on 3rd Embodiment. It is a fragmentary sectional view which shows the modification of a flow sensor part. It is a fragmentary sectional view showing other modifications. It is sectional drawing which follows the XIII-XIII line | wire of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals are given to the same or equivalent parts. Further, the fluid flow direction at normal time is simply referred to as fluid flow direction, and the upstream side indicates the upstream side at normal time and the downstream side indicates the downstream side at normal time. The reverse flow refers to a flow from the downstream side to the upstream side.

(First embodiment)
The flow rate detection device according to the present embodiment detects the flow rate of a fluid using heat transfer with the fluid. In the present embodiment, as an example, in order to detect the flow rate of the air flow (intake flow) sucked into the internal combustion engine (not shown) of the vehicle, a part of the intake pipe 100 is used as shown in FIG. An example of the flow rate detection device 10 detachably attached by a plug-in method so as to protrude inward is shown.

  The flow rate detection device 10 includes a flow path member 11 constituting a flow path and a flow rate sensor unit 12. The flow path member 11 is inserted and disposed in the main flow path 110 in the intake pipe 100 through an attachment hole opened in the intake pipe 100 forming the main flow path 110. The flow path member 11 includes a bypass flow path 11a that takes in a part of the air flowing through the main flow path 110, and a sub-bypass flow path 11b that takes in a part of the air flowing through the bypass flow path 11a.

  In order to detect the flow rate of the air flowing through the sub-bypass channel 11b, the flow rate sensor unit 12 penetrates the channel member 11, protrudes from the inner wall surface to the internal sub-bypass channel 11b, and the channel member 11 Is supported on both ends. That is, the flow sensor unit 12 divides the cross section perpendicular to the fluid flow direction of the sub-bypass channel 11b into two. The sub-bypass channel 11b corresponds to the channel of the channel member described in the claims.

  As shown in FIG. 2, the flow sensor unit 12 supports the sensor chip 20, the support member 30 that supports the sensor chip 20 and exhibits the effect of rectifying the fluid, and protrudes from the support member 30, And a protrusion 40 that connects the member 11 and the support member 30.

  As shown in FIG. 3, the sensor chip 20 includes a substrate 21 made of silicon or the like and a flow rate detection unit 22 formed on a membrane 21 a of the substrate 21. In the present embodiment, a planar rectangular substrate 21 (sensor chip 20) is employed, and the short direction (simply indicated as the short direction) of the sensor chip 20 is the direction along the fluid flow.

  In addition, on the one surface 21b side of the substrate 21, a portion where the concave portion 21d opened to the back surface 21c of the substrate 21 is formed is a thin membrane 21a. The membrane 21 a is formed on one end side far from the inner wall surface of the flow path member 11 in the longitudinal direction of the sensor chip 20 (simply referred to as the longitudinal direction). Hereinafter, the one surface 21b of the substrate 21 is referred to as a flow rate detector forming surface 21b.

  As shown in FIG. 3, the flow rate detection unit 22 includes a heater resistor 23 that generates heat when energized, an upstream temperature measuring resistor 24 u disposed upstream of the heater resistor 23, and a downstream side of the heater resistor 23. And a downstream temperature measuring resistor 24d. The heater resistor 23 is positioned at the center of the membrane 21a in the fluid flow direction, and the temperature measuring resistors 24u and 24d are symmetrical with respect to the heater resistor 23 so as to sandwich the heater resistor 23 between the membrane 21a. In the position.

  The flow rate detection unit 22 of the present embodiment has one temperature measuring resistor 24u and 24d on the upstream side and the downstream side, respectively, but on the upstream side and the downstream side so as to constitute a known bridge circuit, respectively. It is good also as a structure which has two temperature measuring resistances 24u and 24d. Moreover, in order to control the energization state of the heater resistor 23, it is good also as a structure which further has a well-known side heat resistance, temperature measurement resistance, etc.

  In the sensor chip 20 configured as described above, when the flow rate of the fluid flowing through the sub-bypass channel 11b in the channel member 11 increases, the heat transfer of the heater resistor 23 decreases toward the upstream side and increases toward the downstream side. The difference in resistance value between the upstream temperature measuring resistor 24u and the downstream temperature measuring resistor 24d becomes large. On the contrary, when the flow velocity of the fluid in the flow path member 11 becomes small, the heat transfer of the heater resistor 23 tends to be uniform in the upstream and downstream, so that the resistance value of the upstream temperature measurement resistor 24u and the downstream temperature measurement resistor 24d. The difference becomes smaller.

  Thus, the sensor chip 20 forms a temperature distribution in the flow direction of the fluid in the flow path member 11 due to the heat generated by the heater resistor 23, and a signal indicating the intake air amount based on this temperature distribution is sent from an external output terminal (not shown). Output. The signal output from the sensor chip 20 is input to, for example, an electronic control unit (ECU) for controlling the internal combustion engine, and the ECU grasps the intake air amount based on this signal, and the fuel based on the intake air amount. Various control processes such as injection control are executed.

  In addition, as shown in FIG. 4, the sensor chip 20 has a back surface 21c of the flow rate detecting portion forming surface 21b as a mounting surface, and supports the vicinity of the end portion in the longitudinal direction away from the membrane 21a on the back surface 21c. It is bonded and fixed to the fixing portion 31 of the member 30.

  A part of the support member 30 is disposed so as to protrude from the inner wall surface of the flow path member 11 to the internal sub-bypass flow path 11b. And as a part arrange | positioned at the sub bypass flow path 11b, the rectification | straightening part 32 which exhibits the effect which rectifies | straightens the fluid for the flow volume detection part 22 connected with the fixing | fixed part 31 and supporting the sensor chip 20. Have

  The constituent material of the support member 30 is not particularly limited. For example, synthetic resin or ceramic can be used. In this embodiment, it is molded using a synthetic resin such as an epoxy resin or a polyphenylene sulfide resin.

  The fixing portion 31 is a portion of the support member 30 that faces the back surface 21c of the sensor chip 20 (substrate 21) including the opening 21d. In the present embodiment, as shown in FIG. 5, the fixing portion 31 has a flat plate shape with a substantially uniform thickness throughout the entire area.

  As illustrated in FIG. 2, the rectifying unit 32 includes an upstream rectifying unit 33 disposed to face the upstream side surface 20 u of the sensor chip 20 and a downstream rectifying unit 34 disposed to face the downstream side surface 20 d of the sensor chip 20. At least. In the present embodiment, there is further provided a front end side rectifying unit 35 that is disposed opposite to the protruding front end surface 20e of the sensor chip 20 and perpendicular to the upstream side surface 20u and the downstream side surface 20d.

  As described above, the rectification unit 32 exhibits the effect of rectifying the fluid for the flow rate detection unit 22. In order to achieve this effect, as shown in FIG. 5, the upstream side rectification unit 33 has at least the vicinity of the end on the sensor chip 20 side and the flow rate of the back surface 31 b of the sensor chip mounting surface 31 a and the flow rate of the sensor chip 20 in the fixing unit 31. This is a portion having a thickness equivalent to the distance D between the detection portion forming surface 21b (hereinafter, referred to as a uniform thickness portion 33a). One surface of the uniform thickness portion 33 a is flush with the flow rate detection portion forming surface 21 b of the sensor chip 20, and the back surface of the one surface is flush with the back surface 31 b of the fixed portion 31. In the present embodiment, the portion farther from the sensor chip 20 than the uniform thickness portion 33a is a tapered portion 33b that is thinner as it approaches the upstream end portion 33u. In FIG. 5, the boundary between the fixed portion 31 and the upstream rectifying portion 33 is indicated by a dotted line. Further, the upstream end 33u also serves as the upstream end of the support member 30.

  On the other hand, as shown in FIG. 5, the downstream side rectification unit 34 also has at least the vicinity of the end on the sensor chip 20 side so that the back surface 31b of the sensor chip mounting surface 31a in the fixing unit 31 and the flow rate detection unit formation surface 21b of the sensor chip 20. It is a part (henceforth the thickness uniform part 34a) of thickness equivalent to the distance D between these. One surface of the uniform thickness portion 34 a is flush with the flow rate detection portion forming surface 21 b of the sensor chip 20, and the back surface of the one surface is flush with the back surface 31 b of the fixed portion 31. In the present embodiment, the portion further away from the sensor chip 20 than the uniform thickness portion 34a is a tapered portion 34b that is thinner toward the downstream side as it approaches the downstream end portion 34d. In FIG. 5, the boundary between the fixed part 31 and the downstream rectifying part 34 is indicated by a dotted line. Further, the downstream end portion 34 d also serves as the downstream end portion of the support member 30.

  Moreover, the front end side rectification part 35 is connected to each protrusion front end surface of the fixed part 31, the upstream side rectification part 33, and the downstream side rectification part 34, and as shown in FIG. It has a rectangular shape. The range from the uniform thickness portion 33a of the upstream rectifying portion 33 to the uniform thickness portion 34a of the downstream rectifying portion 34 in the fluid flow direction of the distal end rectifying portion 35 is the uniform thickness portions 33a and 34a. It is the uniform thickness part 35a which has the same thickness D. One surface of the uniform thickness portion 35 a is flush with the flow rate detection portion forming surface 21 b of the sensor chip 20, and the back surface of the one surface is flush with the back surface 31 b of the fixed portion 31. Moreover, the part corresponding to taper part 33b, 34b of each rectification | straightening part 33, 34 is a taper part (illustration omitted) which has the shape similar to taper part 33b, 34b. Moreover, in the front end side rectification part 35, the surface opposite to each protrusion front end surface of the fixing | fixed part 31, the upstream rectification part 33, and the downstream rectification part 34 is the open surface 35e which is a free end. The open surface 35e also serves as a protruding tip surface of the support member 30.

  A columnar protrusion 40 is connected to the support member 30 configured as described above. The protrusion 40 connects the support member 30 and the flow path member 11 so that the support member 30 (including the sensor chip 20) that is cantilevered by the flow path member 11 has a dual-support structure. is there. Further, the protrusion 40 has a thickness D that is the distance D between the back surface 31 b of the sensor chip mounting surface 31 a and the flow rate detection portion forming surface 21 b of the sensor chip 20 (the uniform thickness portion of the rectifying unit 32). 33a, 34a, and 35a). In the present embodiment, as shown in FIGS. 4 and 5, the thickness of the protruding portion 40 is thinner than the thickness of the fixing portion 31 and the sensor chip 20. In FIG. 5, the protrusion 40 is indicated by a two-dot chain line as a reference position.

  The constituent material of the protrusion 40 is not particularly limited. In the present embodiment, the protrusion 40 is formed integrally with the support member 30 using the same material (synthetic resin) as the support member 30. In other words, the protrusion 40 is configured as a part of the support member 30.

  Further, the connection position of the protrusion 40 with the support member 30 is not particularly limited. In the present embodiment, the protrusion 40 is connected to the open surface 35e of the distal end side rectifying unit 35 in the support member 30, and extends from the open surface 35e along the protruding direction of the support member 30. Further, as shown in FIG. 4, in the thickness direction, one surface of the protrusion 40 is flush with the flow rate detection portion forming surface 21b of the sensor chip 20, and the back surface of the one surface is from the flow rate detection portion forming surface 21b. Also, the position is close to the back surface 31 b of the fixed portion 31. Further, in the fluid flow direction, as shown in FIG. 2, the upstream end 40u of the protrusion 40 is positioned upstream of the upstream side surface 20u of the sensor chip 20, and the downstream end 40d It is located on the downstream side of the downstream side surface 20 d of the chip 20.

  Further, the shape of the protrusion 40 is not particularly limited. In the present embodiment, the thickness in the vicinity of the center in the flow direction is constant, and the vicinity of the end is tapered like the rectification unit 32. Then, the thickness of the constant thickness portion is the distance D between the back surface 31b of the sensor chip mounting surface 31a and the flow rate detection portion forming surface 21b of the sensor chip 20 in the fixed portion 31 (the uniform thickness portion of the rectifying portion 32). 33a, 34a, and 35a).

  Moreover, the connection state of the protrusion 40 to the flow path member 11 is not particularly limited. In the present embodiment, a part of the protruding portion 40 is provided in a concave portion 11c provided in a portion of the flow path member 11 facing the fixing portion of the support member 30 and filled with a fluorine rubber adhesive such as fluorosilicone. Is inserted and fixed to the flow path member 11 by adhesion.

  In addition, the code | symbol 36 shown in FIG. 4 is a mold part which coat | covers the terminal 37 and the circuit chip which is not shown among the support members 30. FIG. Reference numeral 38 denotes a bonding wire that electrically connects the sensor chip 20 and the terminal 37. The bonding wire 38 and the wire connection portion of the sensor chip 20 and the terminal 37 are integrally sealed with a protective gel 39. Yes.

  Next, the function and effect of the flow rate detection device 10 according to the present embodiment will be described.

  In the present embodiment, as illustrated in FIG. 2, the support member 30 includes an upstream rectification unit 33 and a downstream rectification unit 34 as the rectification unit 32. For this reason, the fluid flowing on the flow rate detection unit 22 of the sensor chip 20 can be rectified by the rectification units 33 and 34. Thereby, the accuracy of flow rate detection can be improved.

  Further, in the present embodiment, the support member 30 includes a tip side rectification unit 35 as the rectification unit 32. For this reason, said rectification effect can be heightened compared with the case where the front end side rectification part 35 is not provided. In addition, since the sensor chip 20 has a shape surrounded by the rectifying unit 32 on three sides, the sensor chip 20 can be easily positioned with respect to the support member 30 (fixed part).

  In the present embodiment, the support member 30 including the sensor chip 20 and the flow path member 11 are connected by the protruding portion 40 protruding from the support member 30. In other words, the flow rate sensor unit 12 is supported at both ends by the flow path member 11 by the protrusion 40. As a result, the resonance frequency of the flow sensor unit 12 can be made higher than in the case of a cantilever support structure that does not have the protrusions 40. In this way, by making the resonance frequency higher than the frequency band of external vibration, it is possible to make it difficult to cause abnormality in flow rate detection due to resonance and damage to the flow rate detection device 10.

  Further, as described above, the thickness of the protrusion 40 is determined by the distance D between the back surface 31b of the sensor chip mounting surface 31a and the flow rate detection unit forming surface 21b of the sensor chip 20 (the thickness of the rectifying unit 32). The thickness of the uniform portions 33a, 34a, and 35a). Thereby, the area occupied by the flow rate sensor unit 12 in the cross section perpendicular to the fluid flow direction of the flow path 11b can be made smaller than that of the conventional structure, and the flow of the fluid can be prevented from being obstructed by the flow rate sensor unit 12. Therefore, it is possible to suppress a decrease in flow rate detection accuracy caused by the flow inhibition.

  In the present embodiment, the protrusion 40 is formed in the same molding process using the same synthetic resin material as that of the support member 30. For this reason, the number of processes can be reduced as compared with the case where the protrusion 40 is formed in a separate process. Further, since the protrusion 40 and the support member 30 are formed of the same material, thermal stress based on the difference in linear expansion coefficient does not occur, and the connection reliability with respect to the temperature of the flow sensor unit 12 is supported by the material of the protrusion 40. Compared with the case where it differs from the member 30, it can be made high.

  In the present embodiment, the protrusion 40 is bonded and fixed in a state where the protrusion 40 is inserted into the recess 11 c of the flow path member 11. The recess 11c is provided in a portion of the flow path member 11 that faces the fixed portion of the support member 30, and the flow sensor unit 12 is connected to the sub-bypass flow in the flow path member 11 with an adhesive disposed in the recess 11c. While projecting into the path 11b, the protrusion 40 can be disposed in the recess 11c. For this reason, a manufacturing process can be simplified. Further, since the protrusion 40 is bonded and fixed to the flow path member 11, the connection reliability can be improved.

(Modification)
In the present embodiment, an example in which the tip of the protrusion 40 is bonded and fixed has been shown. However, the structure for fixing the protrusion 40 to the flow path member 11 is not limited to the above example. For example, as shown in FIGS. 6 and 7, the recess portion 11 c may not be provided in the flow path member 11, and the protrusion 40 may be in direct pressure contact with the flow path member 11. According to this, since the protrusion 40 has a contact point with the flow path member 11, the resonance frequency of the flow rate sensor part 12 cantilevered as in the structure in which the protrusion 40 and the flow path member 11 are bonded. The manufacturing process can be simplified as compared with the adhesive fixing while making the structure higher than the structure.

  In the present embodiment, the example of the synthetic resin is shown as the constituent material of the support member 30. However, for the purpose of improving the connection reliability with the sensor chip 20, linear expansion with silicon forming the substrate 21 of the sensor chip 20 is performed. You may use the ceramic with a near coefficient.

  Further, in the present embodiment, the example in which the protrusion 40 is formed in the same process using the same material as the support member 30 has been described. However, the protrusion 40 may be connected after being formed separately from the support member 30. Further, the support member 30 may be formed of a different material.

  For example, when the protrusion 40 is formed of another material having a Young's modulus larger than that of the support member 30, the Young's modulus increases as a whole of the flow sensor unit 12. Here, the resonance frequency is proportional to the square root of Young's modulus. Therefore, the resonance frequency of the entire flow rate sensor 12 is increased as compared with the structure in which the material of the protrusion 40 is the same as that of the support member 30. That is, the resonance frequency of the flow sensor unit 12 can be freely adjusted by selecting the material of the protrusion 40. By increasing the resonance frequency of the flow rate sensor unit 12 from the frequency band of vibration received from the outside, abnormalities in flow rate detection caused by resonance caused by vibration received from the outside and destruction of the flow rate detection device 10 are less likely to occur.

(Second Embodiment)
In the first embodiment, the upstream end 40u of the protrusion 40 is positioned upstream of the upstream side 20u of the sensor chip 20, and the downstream end 40d is lower than the downstream side 20d of the sensor chip 20. The example located in the downstream was shown (refer FIG. 2). On the other hand, in the present embodiment, as shown in FIG. 8, the upstream end 40u of the protrusion 40 is positioned downstream of the downstream temperature measuring resistor 24d of the sensor chip 20 in the flow direction. , A protrusion 40 is provided.

  In the example shown in FIG. 8, the upstream end 40 u of the protrusion 40 is positioned downstream of the downstream temperature measuring resistor 24 d of the sensor chip 20, and the downstream end 40 d is the downstream end of the support member 30. It is located upstream of the portion 34d.

  Thus, in the present embodiment, the upstream end 40u of the protrusion 40 is located downstream of the downstream temperature measuring resistor 24d of the sensor chip 20 in the fluid flow direction. For this reason, even if a disturbance occurs in the fluid flow due to the protrusion 40, the disturbance hardly acts on the flow rate detection unit 22 such as the downstream temperature measuring resistor 24d located on the upstream side. Therefore, the influence of the fluid disturbance caused by the protrusion 40 on the sensor chip 20 can be suppressed.

(Modification)
In the present embodiment, the upstream end 40u of the protrusion 40 is positioned downstream of the downstream temperature measuring resistor 24d of the sensor chip 20, and the downstream end 40d is the downstream end of the support member 30. The example located in the upstream rather than the part 34d was shown. However, the position of the downstream end 40d of the protrusion 40 is not limited to the above example. For example, the downstream end 40 d of the protrusion 40 may be located on the downstream side of the downstream end 34 d of the support member 30. More preferably, as shown in FIG. 9, the protrusion 40 may be provided so that the downstream end 40 d of the protrusion 40 is flush with the downstream end 34 d of the support member 30. According to this, compared with the structure where there is a step between the downstream end 40d of the protrusion 40 and the downstream end 34d of the support member 30, the disturbance of the flow that occurs when the fluid flows backward is suppressed. be able to.

(Third embodiment)
In the first embodiment, an example in which one surface of the protrusion 40 is flush with the flow rate detecting portion forming surface 21b of the sensor chip 20 in the thickness direction (see FIG. 2). On the other hand, in the present embodiment, as shown in FIG. 10, in the thickness direction, the protrusion 40 is connected to the support member 30 at a portion on the back side of the flow rate detection portion forming surface 21 b of the sensor chip 20. It is characterized by that.

  In the example shown in FIG. 10, the protrusion 40 is located between the flow rate detection portion forming surface 21 b of the sensor chip 20 and the back surface 31 b of the fixing portion 31.

  As described above, in the present embodiment, the protrusion 40 is connected to the support member 30 at a portion on the back surface side of the flow rate detection portion forming surface 21b of the sensor chip 20 in the thickness direction. Thereby, the protrusion 40 which is one of the causes for disturbing the flow is arranged at a position away from the flow rate detection part forming surface 21b of the sensor chip 20. Therefore, the influence of the fluid disturbance caused by the protrusion 40 on the sensor chip 20 can be suppressed.

(Modification)
In the present embodiment, the example in which the protruding portion 40 is positioned between the flow rate detecting portion forming surface 21b of the sensor chip 20 and the back surface 31b of the fixing portion 31 in the thickness direction is shown. However, the connection position of the protrusion 40 is not limited to the above example. In the thickness direction, when the sensor chip 20 side of the flow rate sensor unit 12 is referred to as the upper side and the fixing unit 31 side is referred to as the lower side, a part of the protrusion 40 is positioned below the back surface 31b of the fixing unit 31. It may be. More preferably, as shown in FIG. 11, in the thickness direction, the protruding portion 40 is such that one surface (lower surface) of the protruding portion 40 is flush with the back surface 31 b of the fixing portion 31 of the support member 30. Is preferably provided. According to this, the protrusion 40 is disposed at a position away from the flow rate detection portion forming surface 21b of the sensor chip 20, and the support member including the protrusion 40 is suppressed while suppressing the influence of fluid disturbance on the sensor chip 20. The shape of 30 can be simplified.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In each of the above embodiments, an example in which the flow rate sensor unit 12 is installed in the sub-bypass channel 11b in the channel member 11 has been described. However, the flow path member 11 and the flow path 11b in which the flow rate sensor unit 12 is disposed are not limited to the above example. For example, the flow sensor unit 12 may be directly inserted into the intake pipe 100 and supported at both ends. In this case, the protrusion 40 may be connected to the intake pipe 100. That is, the flow sensor unit 12 may have a structure in which a cross section perpendicular to the fluid flow direction of the main channel 110 is divided into two.

  Further, in each of the above embodiments, the protrusion 40 protruding from the support member 30 has an example of a columnar shape having a constant cross section perpendicular to the protruding direction. However, the shape of the protrusion 40 is not limited to the above example. For example, as shown in FIGS. 12 and 13, the bottom surface may have a conical shape shared with the open surface 35 e of the support member 30. Moreover, it is good also as a hemisphere.

  Further, in each of the above-described embodiments, the example in which the upstream end 40u of the protrusion 40 is disposed on the downstream side of the upstream end 33u of the support member 30 is shown. However, the upstream end 40u of the protrusion 40 may be disposed upstream of the upstream end 33u of the support member 30.

  Further, in each of the above embodiments, in the thickness direction, the protruding portion 40 is flush with the flow rate detection portion forming surface 21b of the sensor chip 20 or is located below the flow rate detection portion forming surface 21b. Indicated. However, a part of the protrusion 40 may be disposed above the flow rate detection part forming surface 21b of the sensor chip 20.

  Further, in each of the embodiments described above, an example in which the protrusion 40 is connected to the distal end side rectifying unit 35 has been shown. However, the connection position of the protrusion 40 is not limited to the above example, and may be a part of the support member 30. For example, the protrusion 40 may be configured to be connected to at least one of the fixing unit 31, the upstream rectification unit 33, or the downstream rectification unit 34. Further, the protrusion 40 is not connected to the protruding front end surface of the support member 30 but to the back surface 31b of the fixed portion 31, the upstream end 33u of the upstream rectifying unit 33, the downstream end 34d of the downstream rectifying unit 34, or the like. It is good also as the structure made.

10 ... Flow rate measuring device 11 ... Channel member 11b ... Sub-bypass channel (channel)
11c: Recess 12: Flow sensor unit 20 ... Sensor chip 22 ... Flow rate detection unit 23 ... Heater resistance 24u ... Upstream temperature measuring resistor 24d ... Downstream temperature measuring resistor 30 ... Support member 31 ... Fixed part 33 ... Upstream rectification part 34 ... Downstream rectification part 35 ... Tip rectification part 40 ... Projection part

Claims (9)

A flow path member (11) through which a fluid flows in an internal flow path (11b);
A part of the flow passage member (11) is disposed so as to protrude from the inner wall surface of the flow passage member (11) to the flow passage (11b) and is supported at both ends by the flow passage member (11). A flow rate sensor device (12) for dividing a cross section perpendicular to the flow direction,
The flow sensor unit (12)
On the one surface (21b) side of the substrate (21), a flow rate detector (23) having a heater resistor (23) and temperature measuring resistors (24u, 24d) respectively located upstream and downstream of the heater resistor (23). 22), the sensor chip (20) in which the flow rate detector (22) is disposed in the flow path (11b),
The sensor chip (20) protrudes from the inner wall surface of the flow path member (11) to the flow path (11b) in a direction perpendicular to the flow direction, and in the thickness direction perpendicular to the protrusion direction and the flow direction. A fixed portion (31) fixed with the surface (21c) opposite to the flow rate detecting portion forming surface (21b) as a mounting surface, and connected to the fixed portion (31) and facing the side surface of the sensor chip (20) And a rectifying unit (32) having at least an upstream rectifying unit (33) positioned upstream from the flow rate detecting unit (22) and a downstream rectifying unit (34) positioned downstream. A support member (30),
A protrusion (40) protruding from the support member (30) and connected to the flow path member (11) and dividing a cross section perpendicular to the fluid flow direction of the flow path (11b) together with the support member (30). ) And
In the thickness direction, the thickness of the protrusion (40) is such that the flow rate detection part forming surface (21b) of the sensor chip (20) and the mounting surface (31a) of the sensor chip (20) in the fixing part (31). ) Is smaller than the distance (D) between the back surface (31b) and the flow rate detection device. The rectifying unit (32) is a tip side rectifying unit disposed opposite to a protruding tip surface (20e) perpendicular to the upstream side surface (20u) and the downstream side surface (20d) of the side surfaces of the sensor chip (20). (35)
The flow rate detection device according to claim 1, wherein the protrusion (40) is connected to the tip-side rectification unit (35).   The upstream end (40u) of the protrusion (40) is disposed downstream of the downstream temperature measuring resistor (24d) of the sensor chip (20) in the flow direction. The flow rate detection device according to claim 1 or 2.   The downstream end (40d) of the projection (40) is disposed flush with the downstream end (34d) of the support member (30). The flow rate detection apparatus of any one of Claims.   In the thickness direction, the protrusion (40) is connected to the support member (30) on the back side of the flow rate detection part forming surface (21b) of the sensor chip (20). The flow rate detection device according to any one of claims 1 to 4.   In the thickness direction, the protrusion (40) is arranged flush with a surface (31b) opposite to the mounting surface (31a) of the sensor chip (20) in the fixing portion (31). The flow rate detection device according to claim 5.   The flow rate detection device according to any one of claims 1 to 6, wherein the protrusion (40) is formed using the same material as the support member (30).   The flow rate detection device according to any one of claims 1 to 6, wherein the protrusion (40) is formed using a material having a Young's modulus larger than that of the support member (30).   The said flow path member (11) has a recessed part (11c) in an inner wall surface, and the said projection part (40) is adhesively fixed, inserting and arrange | positioning in the said recessed part (11c). The flow rate detection device according to any one of? 8.

Images