JP2012103065A - Flow measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow measuring device with excellent detection accuracy.SOLUTION: A flow measuring device comprises: a base 8 that can be fitted in a piping 100 in which a fluid to be measured flows; a flat plate 6 fixed to the base 8; a partially elevated rib 11a (a plate reinforcing part) formed at at least one of a flat part of the plate 6 and having partially projected shape; a cover 9 that has a junction surface joined to the flat part of the plate 6 and in which a continuous groove part formed so as to have a predetermined depth from the junction surface cooperates with the flat part of the plate 6 to constitute a bypass passage 5 of the fluid to be measured; and a flat-shaped flow detection element 3 which is disposed so that a detection surface is exposed in an area constituting the bypass passage 5 of the plate 6 and which measures a flow of the fluid to be measured. The rib 11a is disposed and formed so as to reduce stress which is generated in a direction approximately perpendicular to the detection surface of the flow detection element 3.

Description

  The present invention relates to a flow rate measuring device that outputs a signal in accordance with the flow rate of a fluid to be measured, for example, a flow rate measuring device suitable for measuring an intake air flow rate of an internal combustion engine.

  A flow rate detecting element, which is a detector portion of a flow rate measuring device arranged in a pipe through which a fluid to be measured flows, is joined to a plate member arranged so as to protrude from the inner wall surface of the pipe to the inside of the pipe, and the plate member Is used in a state where the main part is covered with a cover member. The flow rate detecting element and the plate member, and the plate member and the cover member are joined by a thermosetting adhesive (for example, see Patent Document 1).

JP 2009-008619 A

The flow measuring device uses a thin film-shaped semiconductor element as the flow detecting element, but before such a semiconductor element was introduced, a hot-wire flow measuring device was used. The use of a flow rate detecting element made of a semiconductor thin film has caused the following problems that were not found in the case of the hot-wire type.
That is, when a plate to which a semiconductor type flow rate detection element is bonded by a thermosetting adhesive is deformed due to a temperature change, a load is also applied to the bonded flow rate detection element. Is a problem that unexpected stress is generated and detection accuracy is lowered.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a flow measuring device that can reduce stress generated in a flow measuring element and improve detection accuracy. .

  The flow rate measuring apparatus according to the present invention includes a base member that can be fitted into a pipe insertion hole formed in a pipe through which a fluid to be measured flows, and is fixed to the base member and protrudes from the pipe insertion hole side to the pipe inner side. A plate-like plate member inserted so as to have a plate reinforcing portion formed on at least one flat portion of the plate member, and having a partially raised shape, and a joining surface joined to the flat portion of the plate member. A cover member in which a continuous groove portion formed so as to have a predetermined depth from the joint surface cooperates with a flat portion of the plate member to constitute a bypass passage of the fluid to be measured, and the bypass passage of the plate member And a plate-like flow rate detecting element for measuring the flow rate of the fluid to be measured, and the plate reinforcing portion is configured to detect the flow rate. Those which are arranged and formed so as to reduce the stress generated in a direction substantially perpendicular to the detection surface of the child.

  According to the flow rate measuring device of the present invention, since the plate reinforcing portion formed on the plate member is provided, the stress applied to the flow rate detecting element can be reduced and the detection accuracy can be improved.

It is side sectional drawing of the flow volume measuring apparatus required for description of the subject of a prior art. It is sectional drawing and a top view of a plate of a prior art. It is sectional drawing at the time of joining of the plate and flow rate detection element of a prior art. It is sectional drawing and a top view which mounted the circuit board on the plate of a prior art. It is a sectional side view of the flow measuring device of a prior art. It is a sectional side view of the flow measuring device of Embodiment 1 of the present invention. It is a front view of the flow measuring device of Embodiment 1 of the present invention. It is principal part sectional drawing of the flow volume measuring apparatus of Embodiment 1 of this invention. It is a top view of the flow volume detection element of Embodiment 1 of this invention.

It is sectional drawing and the top view of the plate of Embodiment 1 of this invention. It is plate sectional drawing and front view which mount the circuit board of Embodiment 1 of this invention. It is a joint surface side top view of the cover of Embodiment 1 of this invention. It is a plate top view which shows the model of the plate reinforcement part of Embodiment 1 of this invention. It is sectional drawing at the time of joining of the plate and flow-rate detection element of Embodiment 1 of this invention. It is a sectional side view of the flow measuring device of Embodiment 1 of the present invention. It is a front view which shows the bypass channel of the flow volume measuring apparatus of Embodiment 2 of this invention. It is a front view of the flow measurement apparatus which shows the plate reinforcement part of Embodiment 2 of this invention.

It is a front view of the flow measuring device which shows the plate reinforcement part of Embodiment 3 of this invention. It is a sectional side view of the flow measuring device of Embodiment 4 of the present invention. It is a front view of the flow measuring device of Embodiment 4 of the present invention. It is a sectional side view of the flow measuring device of Embodiment 5 of the present invention. It is a front view of the flow measuring apparatus which shows the plate reinforcement part of Embodiment 5 of this invention. It is sectional drawing which shows the fitting state of the plate reinforcement part of Embodiment 5 of this invention, and a fitting groove. It is a rear view of the flow measurement apparatus which shows the plate reinforcement part of Embodiment 6 of this invention. It is a sectional side view of the flow measuring device of Embodiment 6 of this invention. It is a front view of the flow measurement apparatus which shows the plate reinforcement part of Embodiment 7 of this invention. It is a cover joint surface side top view of the flow measuring device of Embodiment 7 of this invention.

Embodiment 1.
First, the problem of the flow rate measuring device of the type using the semiconductor type flow rate detecting element, which has been found by the inventors' consideration, will be described in detail.
The flow rate detecting element is formed with a semiconductor thin film resistor. For this reason, the strength of the resistor is very weak, and it can be said that the structure is brittle against external stress. In addition, the resistance value of the resistor (flow rate detection resistor or temperature compensation resistor) changes due to the stress, causing a problem that the sensor characteristics change. The flow rate detecting element is required to have a mounting structure that is not easily stressed.

Among the components of the conventional flow rate measuring device, the plate with a thin resin wall and a relatively large area is the plate surface when the resin member deforms due to the curing process of the adhesive or the temperature change in the usage environment. Deformation is likely to occur in a direction perpendicular to. Therefore, a load is applied from the plate to the flow rate detection element placed on the plate, and it is considered that there is a problem that unexpected stress is generated in the flow rate detection element and detection accuracy is lowered.
Here, based on the manufacturing process for obtaining the structure of the flow rate measuring device, the inventors' thoughts on the mechanism in which stress is generated in the flow rate measuring element will be described with reference to FIGS.

  A conventional flow rate measuring device 30 shown in FIG. 1 is inserted into an insertion hole 2 provided in the pipe 100 and is used in a state of protruding to the inside of the pipe 100. The flow rate measuring device 30 processes the signal output from the flow rate detecting element 3 by driving the flow rate detecting element 3 and detecting the flow rate of the fluid to be measured (air in the case of an internal combustion engine). A circuit board 4 with a built-in control circuit, a plate (plate member) 6 made of resin on which the flow rate detecting element 3 and the circuit board 4 are mounted, and the plate 6 are joined along the flow direction of the fluid to be measured. A base (base member) 8 having a connector 7 for transmitting and receiving signals between the circuit board 4 and the outside at the end, a bypass passage joined to the plate 6 to guide the fluid to be measured and the flow rate detecting element 3 disposed inside 5 includes a bypass passage groove (groove portion) 19 formed in cooperation with the plate 6 and a cover (cover member) 9 in which a surrounding portion surrounding the circuit board 4 is formed.

  In assembling the flow rate measuring device 30, first, as shown in FIG. 2, the flow rate detection element 3 is placed and bonded to the concave portion 16 provided on the flat surface serving as the joint surface with the cover 9 on the plate 6. Fix it. 2A is a side sectional view of the plate 6, and FIG. 2B is a plan view. The planar contour shape of the plate 6 is a substantially strip shape that is long in one direction, and the longitudinal direction here is the radial direction of the pipe 100 and is the same direction as the insertion direction of the flow rate measuring device 30 into the pipe 100. About half the region in the longitudinal direction (the lower portion in FIG. 2) is a bypass passage forming region 6a that constitutes the bypass passage 5 for allowing the fluid to be measured to pass therethrough, and for placing the flow rate detection element 3 thereon. A recess 16 is formed. The remaining half of the plate 6 joined to the base 8 (closer to the connector 7, the upper part in FIG. 2) is a circuit comprising a frame part for mounting the circuit board 4 for driving the flow rate detecting element 3. This is the substrate placement region 6b.

When the flow rate detecting element 3 is bonded and fixed to the plate 6, it is ideal that the plate 6 and the flow rate detecting element 3 are fixed so that no stress is applied to the plate 6 and the flow rate detecting element 3, as shown in FIG. is there. However, in practice, when the flow rate detecting element 3 is joined to the plate 6, a high temperature treatment using a thermosetting adhesive is performed, so that the following changes occur.
The adhesive used for adhering the flow rate detecting element 3 to the plate 6 is a thermosetting resin, and in the case of a general thermosetting adhesive, it is left to cure for about 30 minutes at a high temperature of 100 ° C. or higher. There is a need. During the thermosetting process, the resin plate 6 thermally expands at a high temperature, and the bypass passage forming region 6a of the plate 6 is deformed in the direction of arrow F as shown in FIG. In this state, the flow rate detecting element 3 is bonded. Note that the load from the plate 6 is not applied to the flow rate detecting element 3 until the adhesive is cured. Here, the deformation amount of the plate 6 shown in FIG. 3B is drawn larger than the actual image by exaggerating the change image. The F direction refers to the direction in which the end of the bypass passage forming region 6a of the plate 6 moves due to deformation due to thermal expansion, and is the direction from the flow rate detecting element 3 mounting surface side of the plate 6 toward the back surface side. is there.

Next, as shown in FIG. 3 (c), after 30 minutes have passed and the adhesive has hardened, it is cooled to room temperature. However, since the resin plate 6 is thin and weak in strength, the arrow G is used during heat shrinkage. Deform in the direction. The direction of arrow G refers to the direction in which the end of the bypass passage forming region 6a of the plate 6 moves due to deformation due to thermal contraction, and is the direction from the back surface side of the plate 6 toward the mounting surface side of the flow rate detecting element 3.
Due to the thermal contraction deformation of the plate 6, the flow rate detection of the flow rate detection element 3 parallel to the plane of the plate 6 so that the plate 6 pushes up a part of the semiconductor type flow rate detection element 3 having a different coefficient of thermal expansion. Stress H is generated in a direction perpendicular to the surface.

Thereafter, as shown in FIG. 4, the circuit board 4 is bonded and fixed onto the circuit board placement region 6 b of the plate 6.
Next, the plate 6 to which the flow rate detecting element 3 and the circuit board 4 are bonded is bonded on the base 8 and after the electrical connection is completed, the cover 9 is attached to the base 8 so as to further close the circuit housing portion and the electrical connection portion. And by adhering on the plate 6, the flow measuring device 30 shown in FIG. 5 is formed.
Therefore, as shown in FIG. 3C, the flow rate detecting element 3 has a stress H (residual stress) perpendicular to the flow rate detecting surface 12 which is a flat surface exposed to the bypass passage. It remains in the state after assembly. However, if this residual stress H does not change, there is no problem as sensor characteristics.

However, in such an actual use environment of the flow rate detection device 30, when exposed to high temperatures, each resin member thermally expands. The problem in this thermal expansion is the deformation of the plate 6 itself and the deformation that is pushed by the cover 9, and the plate 6 that has shrunk due to the thermal curing at the time of assembly gradually increases due to the thermal expansion due to the high temperature. It tries to return to the direction of arrow I which is the shape of FIG.3 (b) before contraction (refer FIG.5). Further, the cover 6 is also pressed by the deformation of the cover 9 in order to return the cover 9 to the thermally expanded state at the time of assembly. The cover 9 is deformed in the direction opposite to the direction indicated by the arrow I. Due to the deformation of the plate 6 and the cover 9 as described above, the deformation of the plate 6 is relieved, the residual stress to the flow rate detecting element 3 is relieved, and becomes the stress J. Due to this stress relaxation, the resistance value of the resistor formed in the flow rate detection element 3 temporarily varies, and the accuracy of flow rate detection is lowered, so that there is a problem that stable detection accuracy cannot be obtained.

  Further, in such an actual usage environment of the flow rate measuring device 30, the resin deteriorates with time and changes in physical properties such as a decrease in Young's modulus. In particular, the deterioration of the resin proceeds remarkably at high temperatures, and a decrease in Young's modulus is observed. Also in this case, the problem is the deformation of the plate 6 itself and the deformation pushed by the cover 9. Due to the change in physical properties as described above, the contracted plate 6 tries to gradually return to the direction of arrow I which is the shape of FIG. 3B before contraction, and the cover 9 also returns to the state of thermal expansion during assembly. A problem similar to that in the case of thermal expansion as shown in FIG. 5 has occurred, such that the plate 6 which is adhesively fixed for the purpose of being pushed is also pushed by the deformation of the cover 9.

Thus, when the inventors ship the flow rate measuring device 30 as a product with the problem that the conventional flow rate measuring device 30 has, that is, with the stress applied to the flow rate detecting element 3, the sensor It was possible to find a problem that the detection accuracy of the flow rate measuring device 30 is lowered due to a temporary change in characteristics at a high temperature or a change that occurs with time due to creep.
In view of this, in the flow rate measuring device of the present invention, a flow rate detecting device is provided in which stress is hardly generated in a direction substantially perpendicular to the flow rate detecting surface 12 of the flow rate detecting element 3 and stable and highly accurate air flow rate detection is possible. It is an object.

Embodiment 1 of the present invention will be described with reference to FIGS. In each figure, the same or equivalent members and parts will be described with the same reference numerals.
FIG. 6 is a side sectional view of the flow rate measuring device (air flow sensor) 1 attached to the pipe 100. The flow rate measuring device 1 is characterized in that a rib (corresponding to a plate reinforcing portion) 11 a that protrudes from a flat surface portion of the plate (plate member) 6 on the joint surface side with the cover (cover member) 9 is provided. . The rib 11 a points to a thick portion raised from the plane of the plate 6, and the rib 11 a is formed to reinforce the plate 6 and reduce the stress generated in the flow rate detection element 3. In the drawing, the vertical direction is the insertion direction of the flow rate measuring device 1 into the pipe 100, and the pipe insertion direction is the same as the longitudinal direction of the plate 6 (indicated by reference numeral 10).

That is, the flow rate measuring device 1 of the present invention is fixed to the base (base member) 8 and the base 8 that can be fitted into the insertion hole (pipe insertion hole) 2 formed in the pipe 100 through which the fluid to be measured flows. A plate-like plate 6 inserted so as to protrude from the hole 2 side toward the inside of the pipe 100, a plate reinforcing portion (rib 11 a) formed on at least one flat portion of the plate 6, and having a partially raised shape, a plate A continuous groove portion (bypass passage groove) formed so as to have a predetermined depth from the bonding surface is joined to the flat portion of the plate 6 in cooperation with the flat portion of the plate 6. A flat flow rate detecting element that is arranged so that a detection surface (flow rate detection surface) is exposed in a region of the cover 9 constituting the bypass passage 5 and the bypass passage 5 of the plate 6 and that measures the flow rate of the fluid to be measured. With 3 Plate reinforcement portion (rib 11a) are arranged and formed so as to reduce the stress generated in a direction substantially perpendicular to the detection surface of the flow rate detection element 3.
Further, the circuit board 4 for driving the flow rate detecting element 3 is disposed in a region overlapping the base 8 on the plate 6, and at least a part of the flow rate detecting element 3, the plate reinforcing portion (rib 11a), and the bypass passage forming region 6a. Is disposed on a region that does not overlap the base 8 on the plate 6. The other configuration is the same as that of the flow rate measuring device 30 shown in FIG. 1 described above. However, as shown in FIG. 6, the shape of the plate 6 itself and the rib 11a are fitted by forming the rib 11a. Needless to say, there is a change in the shape of the cover 9 having the joining surface portion to be joined.

FIG. 7 is a front view showing a planar shape of the rib 11a by cutting out a part of the flow rate measuring device 1 shown in FIG. 1 (the rib 11a is hatched and the layout is highlighted). 6 corresponds to the figure which observed the cross section which followed the dashed-dotted line marked in FIG. 7 from the arrow direction. As shown in the figure, in the region other than the bypass passage 5 on the bypass passage formation region 6a, the streak-like ribs 11a are arranged, and when this substantially Ω-type bypass passage 5 is formed, A total of three strip-like ribs 11a are arranged and formed, one at each end and one at each end.
The rib 11a is in a bypass passage forming region 6a on the plate 6 and serves as a plate reinforcing portion for reducing stress generated in the plate 6 in a direction substantially perpendicular to the flow rate detection surface 12 of the flow rate detection element 3. The rib 11a has a shape including at least a portion extending in the longitudinal direction of the plate 6 in order to reduce the stress. The rib 11a disposed at the center of the bypass passage forming region 6a is affected by the inclined arrangement of the substantially Ω-type bypass passage 5, and has an angle with respect to the longitudinal (vertical) direction as shown in FIG. It is arranged diagonally to have.

  FIG. 8 shows an enlarged cross-sectional view of the main part in the vicinity of the flow rate detecting element 3 of FIG. As shown in FIGS. 6 and 8, the cover 9 is bonded and fixed to the mounting surface side of the flow rate detecting element 3 of the base 8 and the plate 6 at the end. A series of bypass passage grooves (grooves) 19 dug down to a predetermined depth from the joint surface of the cover 9 cooperate with a surface portion (here, a plane portion) on the joint surface side of the plate 6, A bypass passage 5 that guides the fluid to be measured in the pipe 100 is formed on the joint surface with the cover 9. The flow rate detection surface 12 of the flow rate detection element 3 arranged and joined so as to be accommodated in the recess 16 of the plate 6 is also exposed (exposed) to the bypass passage 5 and constitutes a part of the wall surface of the smooth bypass passage 5. ing. The flow rate detection element 3 is electrically connected to the circuit board 4 by a wire 17 by wire bonding. For electrical connection, means such as welding and soldering can be used.

  FIG. 9 is a plan view of the detection surface side of the flow rate detection element 3 of FIG. In FIG. 9, the joining region boundary portion of the cover 9 on the plate 6 is indicated by a broken line, and the cover joining region is indicated by reference numeral 9a. As shown in the sectional view of FIG. 8, the flow rate detecting element 3 is formed of a thin insulating layer formed on the cavity by forming a cavity by etching from the back surface of an insulating plate such as silicon or ceramic. It has a thin part. On the thin portion, a flow rate detection resistor 14 and a temperature compensation resistor 15 as shown in FIG. 9 are formed. These resistors are exposed on the bypass passage 5. In the present invention, a region including the flow rate detection resistor 14 and the temperature compensation resistor 15 of the flow rate detection element 3 is shown as the flow rate detection unit 13.

  FIG. 10 shows a side sectional view (FIG. 10A) and a front view (FIG. 10B) of the plate 6. The plate 6 is formed of, for example, PBT (polybutylene terephthalate) resin. As described above, one end of the plate 6 is the circuit board placement area 6b formed of a window-shaped frame part for bonding and fixing the circuit board 4, and the other end side is the bypass passage forming area 6a. In the bypass passage forming region 6a, a recess 16 for accommodating the flow rate detecting element 3 is formed on a region on which the flow rate detecting element 3 is placed and which serves as the bypass passage 5 on the joint surface side with the cover 9. . A rib 11a, which is a feature of the present application, is formed on a region other than the bypass passage 5 in the bypass passage formation region 6a. This rib 11a extends in the longitudinal direction of the plate 6 so as to reduce the stress generated in the direction substantially perpendicular to the flow rate detection surface 12 of the flow rate detection element 3, and a part of the plate 6 is raised. It is formed in a streak shape.

FIG. 11 shows a side sectional view (FIG. 11 (a)) and a front view (FIG. 11 (b)) in a state where the flow rate detecting element 3 and the circuit board 4 are placed on the plate 6.
FIG. 12 is a front view of the cover (cover member) 9 on the side of the joint surface with the plate 6. The region to be the bypass passage 5 is dug down to a predetermined depth from the joint surface of the cover 9 to form a continuous substantially Ω-shaped groove. The periphery of the bypass passage 5 of the cover 9 is the same height as the joint surface, and a cover recess (fitting groove) 20 into which the rib 11a is fitted is partially dug down symmetrically with the shape of the rib 11a. Is formed. As shown in the cross-sectional view of FIG. 1, the depth of the cover recess 20 is adjusted so that a slight gap is generated when the rib 11 a is fitted, and the gap between the rib 11 a and the cover recess 20 is formed. Is filled with an adhesive, and both are bonded and fixed. In the present invention, the bonding area is increased by the surface area of the rib 11a and the cover recess 20 as compared with the conventional structure shown in FIG. 1, and the adhesive strength between the plate 6 and the cover 9 can be increased. It is.

  By forming the rib 11a, the resin of the plate 6 can be partially thickened, and the bypass passage forming region 6a of the thin plate 6 is reinforced. Further, by limiting the formation direction of the rib 11a, the stress perpendicular to the flow rate detection surface 12 applied to the flow rate detection element 3 can be reduced more effectively. The effective rib arrangement direction is the plate longitudinal direction indicated by the arrow 10 in FIG. As shown in the model diagram of FIG. 13, on the bypass passage forming region 6a, when the length of the rib 11 in the longitudinal direction 10 is a and the length of the short direction 18 is b, b = 0 In other cases, the extending direction of the rib 11 is considered to be the “longitudinal direction” as long as the condition of a> b is satisfied. As shown in FIG. 13, the stress in the direction perpendicular to the flow rate detection surface 12 applied to the flow rate detection element 3 can be reduced also by the ribs 11 arranged and formed at an angle with respect to the longitudinal direction.

Here, the manufacturing process of the flow rate measuring device and the deformation of the plate 6 in the present embodiment will be described with reference to FIG. First, as shown in FIG. 14A, a thermosetting adhesive is applied to the recess 16 in order to adhere the flow rate detection element 3 on the plate 6, and the flow rate detection element 3 is attached.
Next, as shown in FIG. 14B, the resin plate 6 is formed with ribs 11 and is reinforced, so that it is exposed to a high temperature during the heat treatment for curing the adhesive. However, the stress in the direction of arrow A generated by thermal expansion is reduced, and the amount of deformation can be made smaller than that of the structure without the rib 11 (the structure of FIG. 3B).
Next, as shown in FIG. 14 (c), even when the resin shrinks due to cooling after curing the adhesive, the rib 11 suppresses deformation in the direction of arrow B to return to the original position of the plate 6, and the flow rate is reduced. The stress C applied perpendicular to the flow rate detection surface 12 of the detection element 3 is reduced.

Thereafter, the circuit board 4 is bonded to the plate 6, the plate 6 having the flow rate detecting element 6 and the circuit board 4 bonded is bonded to the base 8, and after the electrical connection is completed, the circuit storage unit and the electrical connection unit are further closed. Thus, the cover 9 is adhered on the base 8 and the plate 6 to obtain the flow rate measuring device 1 shown in FIG.
As shown in FIG. 6, also in the flow rate measuring device 1 of the present invention, the base 8 has a connector 7 on the insertion hole 2 side for exchanging signals with the outside, and one end of the connector 7 At the same time as a terminal, a terminal for the circuit board 4 whose other end is electrically connected to the circuit board 4 is integrally formed by molding. A plate 6 is bonded and fixed to the terminal side.

According to the flow rate measuring apparatus 1 as shown in FIG. 15, even when resin deterioration or temperature change occurs in the plate 6, the direction of the arrow D (flow rate) in which the plate 6 tries to return to the original state by the rib 11 a formed on the plate 6. The deformation in the same direction as the deformation direction A at the time of bonding of the detection element 3 is suppressed, and even when the deformation occurs, the amount of deformation is small, so that the stress E generated in the flow rate detection element 3 can be reduced. It becomes possible.
Further, as shown in the model diagram of FIG. 13, the rib 11 formed on the plate 6 has an angle in the longitudinal direction 10 of the plate 6 when the condition of a> b (see FIG. 13) is satisfied. Also in the rib 11 formed in this manner, the reinforcing effect of the present invention can be obtained efficiently. Needless to say, when b = 0 which does not have an angle, the reinforcing effect by the rib 11 can be obtained most efficiently.

Further, the rib 11 a and the cover recess 20 are fitted and bonded to each other, so that the stress reducing rib to the flow rate detecting element 3 and the bonding rib with the cover 9 can be shared. The flow rate detector is downsized in consideration of the fact that it is placed in an engine room where the space is small or the pressure loss must be reduced because it is installed in the piping through which intake air flows into the engine. Is required. On the other hand, even when downsizing is required, since the bypass passage 5 and the like occupy a certain space, it is difficult to separately arrange the stress reducing rib and the adhesive rib. Therefore, as in the present embodiment, by sharing the stress reducing rib and the adhesive rib, the limited space can be used effectively, and the flow rate detecting device can be downsized.
As described above, the surface area can be increased by the concave and convex shapes of the rib 11a and the cover concave portion 20, and the bonding area when the adhesive is cured with an adhesive or the like can be increased and the adhesive strength can be improved. Furthermore, the formation of the cover recess 20 can also provide an effect of improving workability and workability such as bonding positioning.
In the above example, the rib 11a has been shown to be three streaks arranged with a passage therebetween, but only one (central part) or two (both ends) of the three are provided. It can also be arranged.
Furthermore, a series of ribs 11a can be divided into arbitrary lengths according to the shape of the passage as long as stress can be reduced to the flow rate detection element 3, and can be formed as a group of protrusions arranged intermittently. is there.

Embodiment 2. FIG.
In the first embodiment described above, one opening of the bypass passage 5 is formed in the lower portion of the left end portion of the bypass passage formation region 6a in the front view of the flow rate measuring device 1 in FIG. An example is shown in which the other opening is formed in the central part on the lower end side through a meandering, meandering passage. In the second embodiment, as shown in FIG. 16, one opening portion of the bypass passage 5a is formed in the lower part of the left end portion similar to the first embodiment, and is bent into a substantially Ω shape. Through the above, a rib shape suitable for the case where the other opening is formed in the lower part of the right end is proposed.
In the second embodiment, the bypass passage 5 a has a planar shape and is Ω-shaped with no left-right symmetry, and a part thereof is formed along the longitudinal direction 10 of the plate 6. With the change in the shape of the bypass passage 5a, the rib-arrangeable region 21 is a hatched region in FIG. 16, that is, the middle portion of the bypass passage forming region 6a in FIG. A wide part that extends and a part that extends upward from the openings at the left and right end portions.

FIG. 17 is a front view showing a flow rate measuring device 1a according to Embodiment 2 of the present invention, and is a front view showing a state in which ribs 11b are formed on the flow rate measuring device 1a of FIG. In FIG. 17, the rib 11b is hatched to emphasize the arrangement.
In the second embodiment, the bypass passage 5 a is formed so as to extend in the vertical direction along the longitudinal direction 10 of the plate 6, and the rib-arrangeable region 21 where the bypass passage 5 a is not formed is provided along the longitudinal direction 10. It is a pattern that can be. Therefore, as shown in FIG. 17, by using the rib-arrangeable region 21, it is possible to form the rib 11b having only a plate longitudinal component having a high reinforcing effect. Since the short component of the rib 11b is close to zero, the same stress reduction effect as in the first embodiment can be more reliably exhibited.

  In particular, by adopting a substantially Ω-type bypass passage 5a structure having a long longitudinal path as shown in the second embodiment, the first Ω-type structure is inclined more than the first embodiment in which the substantially Ω-type is arranged obliquely, and from both ends of the plate 6. In addition, a wide rib-arrangeable area 21 can be provided in the middle of the plate 6, and the wide rib-arrangeable area 21 is used to be disposed in the middle of the plate 6 in the first embodiment or both ends. The rib 11b having a width wider than that of the one can be formed. Since the wide rib 11b can be disposed in the vicinity of the flow rate detecting element 3 and in the vicinity of the center of the bypass passage forming region 6a on the plate 6, the Ω shape of the bypass passage 5 is arranged obliquely as in the first embodiment. A more effective plate reinforcement effect can be obtained than the ribs arranged with the ribs.

  In addition, in FIG. 17, the example which formed the width | variety of the rib 11b arrange | positioned in the center part wider than the thing of both ends showed the width | variety of one rib 11b as the same dimension as the thing of both ends, Needless to say, it is also possible to increase the number of the central portion only. Further, the surface area of the rib 11b can be increased by increasing the number, and the bonding area with the cover 9 can be increased to increase the bonding strength.

Embodiment 3 FIG.
FIG. 18 is a view showing a flow rate measuring device 1b according to Embodiment 3 of the present invention, and is a front view in which a part of the flow rate measuring device 1b is cut away.
In the third embodiment, ribs 11c (formation areas are indicated by meshes) are formed along the outer periphery of the passage constituting the crank-type bypass passage 5b. As shown in FIG. 18, the crank-type bypass passage 5b has a path that advances from one opening formed in the lower part of the left end to the right, further upward, and further to the right. The passage of the type which reaches the other opening provided in the upper part of the right end. Other configurations are the same as those in the second embodiment.

  In the third embodiment, a rib 11c is formed along the outer periphery of the crank-type bypass passage 5b. Therefore, the longitudinal component (the portion satisfying b = 0) of the rib 11c can be effectively arranged in the central portion of the bypass formation region 6a to ensure the plate reinforcement effect, suppress the deformation of the plate 6, and reduce the flow rate. The stress applied to the detection element 3 can be reduced.

Embodiment 4 FIG.
In the fourth embodiment of the present invention, a structure that can be applied to the first to third embodiments described above and that improves the adhesive strength between the plate 6 and the cover 9 will be described. FIG. 19 is a side sectional view showing the flow rate measuring device 1c, and FIG. 20 is a front sectional view of the main part of the flow rate measuring device 1c in FIG. The cross section in FIG. 20 shows a cross section at an intermediate position between the fitting depth of the rib 11a and the cover recess 20. In the fourth embodiment, the surface portion of the rib 11a and the surface portion of the cover recess 20 formed as an adhesive groove in the cover 9 are replaced with the surface portion of the plate 6 constituting the bypass passage 5c and the surface portion of the groove portion 19 of the cover 9. Rather than roughening.

This is because the surface portion of the plate 6 constituting the bypass passage 5c and the surface portion of the groove portion 19 of the cover 9 are smoothed to reduce the resistance in order to improve the passage of the fluid to be measured. On the other hand, the surface portion of the rib 11a and the surface portion of the cover recess 20 remain roughened to increase the surface area and increase the bonding area to improve the bonding strength.
The smoothed surface portion (plate 6 joint surface and groove portion 19) constituting the bypass passage 5c is realized by polishing a corresponding portion of a mold used when the plate 6 and the cover 9 are integrally molded with resin. The roughened surface portions of the ribs 11a of the plate 6 and the cover recess 20 of the cover 9 can be realized by leaving the corresponding portions of the mold to be roughened without polishing. Is possible.

Embodiment 5 FIG.
21 is a side sectional view showing a flow rate measuring device 1d according to Embodiment 5 of the present invention, FIG. 22 is a front view of FIG. 21, and FIG. 23 is an enlarged view of a main part of FIG.
In the above-described first to third embodiments, the example in which the ribs 11 are arranged on the outer peripheral portion of the bypass passage 5 (5a, 5b) has been described. However, in the fifth embodiment, at least the circuit board 4 and the bypass passage 5 are provided. The case where the rib 11d which is arrange | positioned between these and has the effect of preventing the adhesive agent leakage to the bypass passage 5 side is formed is demonstrated. In the example of FIG. 22, the rib 11 d is shown not only between the circuit board 4 and the bypass passage 5 but also arranged around the circuit board 4 positioned at the end of the plate 6.

  In the fifth embodiment, as shown in the cross-sectional view of FIG. 23, the rib 11d fitted to the cover recess 20 is fitted asymmetrically with respect to the opening width direction of the cover recess 20, thereby providing a cover recess. A space for storing the adhesive can be formed on the circuit board 4 side in the inside 20. Since there is a space (adhesive reservoir) provided on the side of the circuit board 4 in the cover recess 20 serving as the fitting groove, the adhesive used when the plate 6 and the cover 9 are bonded is connected to the side of the circuit board 4 (arrow K). Therefore, the adhesive can be prevented from protruding into the bypass passage 5. Intrusion of the adhesive into the bypass passage 5 for detecting the flow rate in the flow measuring device 1d greatly affects the detection characteristics. Therefore, the detection accuracy is improved by suppressing the protrusion of the adhesive into the bypass passage 5. Can be made.

Embodiment 6 FIG.
24 is a rear view showing a flow rate measuring device 1e according to Embodiment 6 of the present invention, and FIG. 25 is a side sectional view of the flow rate measuring device 1e. In the above-described first embodiment, the rib 11a is formed on the flow detection element 3 mounting surface (front surface) side of the plate 6, but in this sixth embodiment, what is the flow detection element 3 mounting surface of the plate 6? A rib 11e is formed by partially raising the opposite plate flat surface (back surface).

  In the sixth embodiment, a rib 11e of b = 0 extending in the longitudinal direction is provided on the surface of the plate 6 opposite to the surface on which the flow rate detecting element 3 is mounted, regardless of the shape of the bypass passage 5, and the plate 11 bypasses the rib 11e. It can arrange | position on the channel | path formation area 6a. Since the rib 11e does not need to consider the shape of the bypass passage 5, it can be formed longer and thicker in the longitudinal direction of the plate 6 and can be arranged in a larger number.

Embodiment 7 FIG.
FIG. 26 shows a plan view of the flow rate measuring device 1 in which the ribs 11f (emphasized by adding hatching to the planar shape) of the seventh embodiment of the present invention are formed. The rib 11f has a shape obtained by deforming the one disposed in the central portion of the three ribs 11a of the first embodiment, and the protruding contour shape of the rib 11f is the side surface of the central portion of the bypass passage 5 It coincides with the shape (inner peripheral side), and the height of the protruding rib 11 f is the same as the depth of the cover recess 20. Of the three ribs 11a, two at both ends have the same shape as the rib 11a of the first embodiment.

Further, FIG. 27 shows a plan view of the joining surface side of the cover 9 of the first embodiment. As shown in FIG. 27, the region where the rib 11f of the cover 9 is joined is dug down to a depth corresponding to the bypass passage groove 19, and no fitting groove into which the rib 11f is fitted is formed.
In the flow rate measuring device 1 according to the seventh embodiment, the protruding surface of the rib 11f and the groove bottom surface of the cover 9 are bonded, and the rib 11a and the cover concave portion 20 are fitted in the other regions as in the first embodiment. Glue together. At this time, a part of the bypass passage 5 is constituted by a rising side surface portion of the rib f. Since the rib 11f can be largely arranged in the center of the bypass passage forming region 6a of the plate 6, the plate 6 can be reinforced more effectively.

Moreover, although the example which forms the protrusion amount of the rib 11f so that it may become the same as the depth of the groove part which comprises the bypass passage 5 of the cover 9, the protrusion amount of the rib 11f was made into 1/2 of the groove part depth. In this case, the reinforcing strength of the rib 11f can be adjusted, for example, by setting the digging amount of the region of the cover 9 where the rib 11f is joined to ½ of the groove depth.
Furthermore, in the above example, it has been described that the rib 11f constituting a part of the outline of the bypass passage 5 has a pattern arranged in the central portion of the bypass passage formation region 6a, but is located at both ends. It is also possible to apply this structure to the ribs.

1, 1a, 1b, 1c, 1d, 1e Flow rate measuring device 2 Insertion hole 3 Flow rate detecting element 4 Circuit board 5, 5a, 5b Bypass passage 6 Plate (plate member)
6a Bypass passage formation area 6b Circuit board placement area 7 Connector 8 Base (base part)
9 Cover (cover member)
10 Longitudinal direction 11, 11a, 11b, 11c, 11d, 11e, 11f Rib (plate reinforcing part)
DESCRIPTION OF SYMBOLS 12 Flow rate detection surface 13 Flow rate detection part 14 Flow rate detection resistor 15 Temperature compensation resistor 16 Recessed part 17 Wire 18 Short direction 19 Bypass passage groove (groove part)
20 Cover recess (fitting groove)
30 Flow rate measuring device (conventional)
100 piping.

Claims (14)

  A base member that can be fitted into a pipe insertion hole drilled in a pipe through which the fluid to be measured flows, and a flat plate that is fixed to the base member and inserted so as to protrude from the pipe insertion hole side to the pipe inner side The plate member is formed on at least one flat portion of the plate member, and has a partially raised plate reinforcing portion and a joint surface joined to the flat portion of the plate member, and has a predetermined depth from the joint surface. A detection surface appears in a region in which the continuous groove portion formed in this way forms a bypass passage for the fluid to be measured in cooperation with the flat portion of the plate member, and a region constituting the bypass passage of the plate member. A flat plate-like flow rate detecting element that measures the flow rate of the fluid to be measured, and the plate reinforcing portion is substantially perpendicular to the detection surface of the flow rate detecting element. Flow measuring device is characterized in that formed and arranged as to reduce the stress generated in the direction.   The plate reinforcing portion is formed on a side of the plate member joined to the cover member, and a concave portion for fitting the plate reinforcing portion is formed on the joint surface side of the cover member. The flow measurement device according to claim 1.   The flow rate measuring device according to claim 1, wherein the plate reinforcing portion includes a portion extending linearly along a protruding direction of the plate member toward the inside of the pipe.   The flow rate measuring device according to claim 1, wherein the plate reinforcing portion is disposed and formed in a region other than a region where the bypass passage is formed on the flat portion of the plate member.   The flow rate measuring device according to claim 4, wherein the plate reinforcing portion is formed along an outer peripheral portion of a region where the bypass passage is formed.   The plate reinforcing portion is formed on the other surface side of the plate member that is not a joint surface with the cover member so as to extend in a streak shape along a protruding direction of the plate member toward the inside of the pipe. The flow rate measuring device according to claim 1.   A circuit board for driving the flow rate detecting element is disposed in a region overlapping the base member on the plate member, and at least a part of the flow rate detecting element, the plate reinforcing portion, and the bypass passage forming region are arranged on the plate. The flow rate measuring device according to claim 1, wherein the flow rate measuring device is disposed on a region of the member that does not overlap the base member.   2. The flow rate measuring device according to claim 1, wherein the plate reinforcing portion is located on the plate member between the circuit board and a region where the bypass passage is formed.   The flow rate measuring device according to claim 2, wherein the plate reinforcing portion and the concave portion of the cover member fitted to the plate reinforcing portion are fixed by an adhesive.   The flow rate measuring device according to claim 9, wherein an adhesive pool portion for storing the adhesive is provided between the plate reinforcing portion and the concave portion of the cover member.   2. The flow rate measuring device according to claim 1, wherein the plate member is made of resin.   The flow rate measuring device according to claim 1, wherein a surface portion of the plate reinforcing portion is rougher than a surface portion constituting the bypass passage of the plate member. The flow rate measuring device according to claim 2, wherein a surface portion of the concave portion of the cover member is rougher than a surface portion of the groove portion constituting the bypass passage of the cover member.   The flow rate measuring device according to claim 1, wherein the flow rate detecting element is bonded to the plate member with a thermosetting adhesive.

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