JP2012225699A - Air flow rate measurement apparatus and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of an air flow rate measurement apparatus by assisting leakage prevention of air from an inner flow channel 5 by a seal material 9.SOLUTION: In a method for manufacturing the air flow rate measurement apparatus, an integrated object 38 is set on a metal mold so that a hole axis intersects with an injection port 41 of secondary molding resin and an arrangement part 39 outside a housing is opposed to a hole axis direction in a molding step. Consequently the secondary molding resin presses a sensor assembly 4 to the hole axis direction and an engagement part 4K of the sensor assembly 4 is strongly abutted on an engagement part 7K of a housing 7. Thereby a gap 8 formed between a hole surface of an engagement hole 6 and the surface of the sensor assembly 4 is more airtightly blocked in an abutting area between the engagement parts 4K, 7K, so that leakage prevention of the seal material 9 is strongly assisted by abutting enhancement between the engagement parts 4K, 7K.

Description

  The present invention relates to an air flow rate measuring device that measures the flow rate of air, and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, a thermal air flow rate measuring device that measures an air flow rate using heat transfer with air is known. For example, an air flow measuring device that is disposed in an intake passage to an internal combustion engine and sucked into the internal combustion engine is known. It is used to measure the flow rate.

  This conventional air flow measuring device 100 includes, for example, a sensor assembly 101 that holds a sensor chip (not shown) that generates an electric signal by heat transfer with air, and an internal flow path 102 through which air passes. A housing 103 into which the sensor assembly 101 is fitted so that the sensor chip protrudes into the internal flow path 102 and a gap 104 formed around the sensor assembly 101 and formed between the housing 103 and the sensor assembly 101. The sealing material 105 that prevents air from leaking from the internal flow path 102, the sensor assembly 101, the housing 103, the sealing material 105, etc. are set in a predetermined mold, and a secondary molding resin is injected. The secondary mold part 106 obtained by this is provided.

The sensor assembly 101 also has a terminal 107 for outputting an electrical signal. The terminal 107 protrudes from the surface of the sensor assembly 101 on the downstream side of the sealing material 105 with respect to the air flow leaking from the internal flow path 102 through the gap 104.
Thereby, by arranging the terminal 107 on the downstream side of the sealing material 105, it is possible to suppress the adhesion of moisture contained in the air to the terminal 107, and the moisture adhered to the terminal 107 leaks toward the connector 108, Intrusion into the sensor assembly 101 is suppressed.

  In other words, in the air flow rate measuring device 100, the sealing material 105 prevents leakage of air passing through the internal flow path 102, so that moisture enters an area where electrical continuity exists, such as the terminal 107, and an unintended short circuit or the like occurs. It suppresses the occurrence and maintains reliability.

  By the way, in order to further improve the reliability of the air flow rate measuring device 100, it has been studied to enhance the prevention of air leakage from the internal flow path 102. As one of the strengthening measures, the leakage prevention by the sealing material 105 is considered. There is a need for a structure that can assist. Further, when an adhesive or the like is used as the sealing material 105, there is a possibility that the sealing material 105 leaks toward the internal flow path 102, and a structure capable of suppressing such leakage of the sealing material 105 is also provided. It has been demanded.

Thus, for example, it is conceivable to apply the manufacturing methods shown in Patent Documents 1 and 2.
According to FIG. 1 and FIG. 2 of Patent Document 1, a resin molded product 1 to be manufactured has a cavity 2 that bends at a right angle. Then, in the molding process of the resin molded product 1, the auxiliary mold 15 that forms the horizontal hole 2 a is sandwiched between the auxiliary mold 14 that forms the vertical hole 2 b and the insert part 3, and further, the auxiliary mold 15 is auxiliary from the lower side of the insert part 3. The insert part 3 is pressed against the auxiliary mold 15 by the mold 18.

As a result, a part of the wall of the cavity 2 is constituted by the insert part 3 and unnecessary openings and burrs are prevented from occurring when the entire wall of the cavity 2 is constituted only by the resin molded part 1a. ing.
However, since the insert part 3 is exposed to the outside in addition to the cavity 2, if it is necessary to more strictly prevent leakage from the cavity 2, it is necessary to separately provide a leakage prevention means, which increases costs. End up.

Moreover, according to FIG. 4 of patent document 2, it butt | matches so that the butt | matching part TB of the primary semi-molded product B may be fitted to the butt | matching part TA of the primary semi-molded product A, and also injects molten resin into the butt | matched area | region. Then, the primary semi-molded products A and B are integrated.
However, the higher the injection pressure of the molten resin, the higher the risk that the molten resin will enter a narrow gap and protrude to the hollow side.

JP-A-8-142111 Japanese Patent Application Laid-Open No. 9-155921

  The present invention has been made to solve the above-described problems. The first object of the present invention is to increase the cost of the air flow measuring device without increasing the cost, and to the inner flow path side of the resin for secondary molding. The second objective is to improve the reliability by assisting the prevention of air leakage from the internal flow path by the sealing material without causing the protrusion, and the second purpose is to prevent the leakage of the sealing material to the internal flow path side. It is to suppress.

[Means of Claim 1]
According to the means of claim 1, the air flow rate measuring device includes a sensor assembly that holds a sensor chip that generates an electric signal by heat transfer with air, an internal flow path through which air passes, and a sensor in the internal flow path A housing having a fitting hole into which a part of the sensor assembly is fitted so that the chip protrudes, and a gap formed around the sensor assembly and formed between the hole surface of the fitting hole and the surface of the sensor assembly A secondary material obtained by injecting a secondary molding resin after setting the sensor assembly, the housing and the sealing material in a predetermined mold. A mold part.

  The fitting hole has a linear hole shaft so that the sensor assembly can be moved linearly, and the sensor assembly and the housing are fitted in contact with each other. It has an engaging part which controls fitting of the sensor assembly in a joint hole. Then, the engaging portion of the sensor assembly and the engaging portion of the housing come into contact with each other after being brought close to each other in the direction of the hole axis by fitting into the fitting hole of the sensor assembly, and the sensor assembly is fitted. To regulate.

  Accordingly, for example, when the secondary mold portion is molded, the sensor assembly is pressed in the direction of the hole axis by the flow pressure of the secondary molding resin, so that the engagement portion of the sensor assembly is strongly applied to the engagement portion of the housing. Can be touched. For this reason, the gap formed between the hole surface of the fitting hole and the surface of the sensor assembly is more airtightly sealed in the contact area between the engaging portions. It is strongly assisted by strengthening the contact between the joints.

  As described above, the air flow measuring device assists in preventing air leakage from the internal flow path by the sealing material without increasing the cost and without causing the secondary molding resin to protrude into the internal flow path. Reliability.

[Means of claim 2]
According to the means of claim 2, the sealing material is downstream of the position where the engaging portion of the sensor assembly and the engaging portion of the housing exist with respect to the flow direction of the air leakage from the internal flow path passing through the gap. Placed in.
Thereby, when the sealing material flows toward the internal flow path through the gap, the seal material reaches the contact area between the engaging portions before reaching the internal flow path. For this reason, leakage of the sealing material toward the internal flow path can be suppressed by strengthening the contact between the engaging portions.

[Means of claim 3]
According to the third aspect of the present invention, the engaging portion of the sensor assembly and the engaging portion of the housing each have an abutting surface that comes into surface contact with each other when abutting. The contact surface on the sensor assembly side and the contact surface on the housing side are inclined so as to be closer to the hole axis as they are closer to the internal flow path.

  Thereby, a wedge effect is obtained by the abutment between the engaging portions, and the abutment surface of the sensor assembly comes into more powerful surface contact with the abutment surface of the housing. For this reason, since the gap formed between the hole surface of the fitting hole and the surface of the sensor assembly can be more airtightly sealed in the contact area between the engaging portions, the leakage prevention assist is further improved. The reliability of the air flow rate measuring device can be enhanced by strengthening.

[Means of claim 4]
According to the fourth aspect of the present invention, in the method for manufacturing the air flow rate measuring device, the sensor chip is protruded into the internal flow path by moving the sensor assembly in the direction of the hole axis and fitting in the fitting hole. And a second preparatory step in which the sealing material is arranged around the sensor assembly, and an integrated body of the sensor assembly, the casing and the sealing material constituted by the first preparatory step and the second preparatory step is set in a mold, A molding step of injecting a secondary molding resin to mold the secondary mold part.

  In the molding step, a portion of the sensor assembly that is arranged outside the casing (hereinafter referred to as an outside casing arrangement section) so that the hole axis intersects the injection port of the secondary molding resin. ) Is set on the mold so that the nozzle faces the injection port in the direction of the hole axis.

  As a result, the secondary molding resin is injected from the injection port in the direction of the hole axis and collides with the outer housing arrangement portion in the direction of the hole axis and presses the sensor assembly in the direction of the hole axis. The joint part strongly contacts the engaging part of the housing. For this reason, the gap formed between the hole surface of the fitting hole and the surface of the sensor assembly is more airtightly sealed in the contact area between the engaging portions. It is strongly assisted by strengthening the contact between the joints.

  As described above, the air flow measuring device assists in preventing air leakage from the internal flow path by the sealing material without increasing the cost and without causing the secondary molding resin to protrude into the internal flow path. Reliability.

[Means of claim 5]
According to the means of claim 5, the sensor assembly has a terminal for outputting an electrical signal, and the terminal projects from the predetermined projecting surface in the direction of the hole axis. In the molding step, the integrated object is set in the mold so that the protruding surface faces the injection port in the direction of the hole axis.
Thereby, since the resin for secondary molding flows in parallel with the hole axis along the terminal, it is possible to suppress the terminal from falling down due to the flow pressure of the resin for secondary molding.

[Means of claim 6]
According to the sixth aspect of the present invention, in the molding step, the integrated object is set in the mold so that a part of the surface of the sensor assembly is opposed to the injection port and the hole axis. A portion of the surface of the sensor assembly that faces the injection port in the direction of the hole axis is provided in a tapered shape that tapers toward the injection port.

  Thereby, the secondary molding resin flowing from the injection port can collide with the surface portion facing the injection port in the direction of the hole axis, and can flow substantially along the surface of the sensor assembly. . For this reason, the fall of the sensor assembly due to the flow pressure of the secondary molding resin can be suppressed.

It is sectional drawing which shows the inside of an air flow measuring device (Example 1). (A) is AA sectional drawing of FIG. 1, (b) is a fragmentary sectional view which shows the principal part of an air flow rate measuring apparatus (Example 1). It is explanatory drawing which shows the 1st preparatory process of the manufacturing method of an air flow measuring device (Example 1). (A) is explanatory drawing which shows the 2nd preparatory process of the manufacturing method of an air flow measuring device, (b) is explanatory drawing which shows the formation process of the manufacturing method of an air flow measuring device (Example 1). (Example 2) which is a fragmentary sectional view which shows the principal part of an air flow measuring device. It is a fragmentary sectional view of an air flow measuring device (conventional example).

  The air flow rate measuring apparatus according to the first embodiment includes a sensor assembly that holds a sensor chip that generates an electrical signal by heat transfer with air, an internal channel through which air passes, and a sensor chip that protrudes into the internal channel. And a housing having a fitting hole into which a part of the sensor assembly is fitted, and a gap formed between the hole surface of the fitting hole and the surface of the sensor assembly, which is disposed around the sensor assembly and sealed. A sealing material for preventing air from leaking from the flow path, and a secondary mold portion obtained by setting the sensor assembly, the casing, and the sealing material in a predetermined mold and injecting a resin for secondary molding. .

The fitting hole has a linear hole shaft so that the sensor assembly can be moved linearly, and the sensor assembly and the housing are fitted in contact with each other. It has an engaging part which controls fitting of the sensor assembly in a joint hole. Then, the engaging portion of the sensor assembly and the engaging portion of the housing come into contact with each other after being brought close to each other in the direction of the hole axis by fitting into the fitting hole of the sensor assembly, and the sensor assembly is fitted. To regulate.
Furthermore, the sealing material is arranged on the downstream side of the position where the engaging portion of the sensor assembly and the engaging portion of the housing are present in the flow direction of the air leakage from the internal flow path passing through the gap.

In addition, the manufacturing method of the air flow measuring device according to the first embodiment includes a first preparation step of causing the sensor chip to protrude into the internal flow path by moving the sensor assembly in the direction of the hole axis and fitting the fitting into the fitting hole, and a seal A second preparatory step in which the material is arranged around the sensor assembly, and an integrated body of the sensor assembly, the casing, and the seal member constituted by the first preparatory step and the second preparatory step is set in a mold for secondary molding And a molding step of molding a secondary mold part by injecting resin.
In the molding process, a portion (outside of the casing) of the sensor assembly that is arranged outside the casing so that the hole axis intersects with the secondary molding resin injection outlet The monolith is set in the mold so as to face the direction of the hole axis.

The sensor assembly has a terminal for outputting an electrical signal, and the terminal protrudes from the predetermined protruding surface in the direction of the hole axis. In the molding step, the integrated object is set in the mold so that the protruding surface faces the injection port in the direction of the hole axis.
Furthermore, in the molding process, the integrated object is set in the mold so that a part of the surface of the sensor assembly is opposed to the injection port and the hole axis. A portion of the surface of the sensor assembly that faces the injection port in the direction of the hole axis is provided in a tapered shape that tapers toward the injection port.

  According to the air flow rate measuring apparatus of the second embodiment, the engaging part of the sensor assembly and the engaging part of the housing each have a contact surface that comes into surface contact with each other at the time of contact. The contact surface on the sensor assembly side and the contact surface on the housing side are inclined so as to be closer to the hole axis as they are closer to the internal flow path.

[Configuration of Example 1]
The configuration of the air flow rate measuring apparatus 1 according to the first embodiment will be described with reference to FIGS. 1 and 2.
The air flow rate measuring device 1 measures the air flow rate using heat transfer with air, and is, for example, disposed in an intake passage 2 to an internal combustion engine (not shown) and sucked into the internal combustion engine. It is used to measure the flow rate of air (hereinafter sometimes referred to as intake air).

  In addition, the air flow measuring device 1 includes, for example, a sensor assembly 4 that holds a sensor chip 3 that generates an electrical signal by heat transfer with air, an internal flow path 5 through which air passes, and a sensor in the internal flow path 5. A housing 7 having a fitting hole 6 into which a part of the sensor assembly 4 is fitted so that the chip 3 protrudes, and a hole surface of the fitting hole 6 and a surface of the sensor assembly 4 are arranged around the sensor assembly 4. A seal material 9 that seals the gap 8 formed between the two and prevents the air from leaking from the internal flow path 5, and the sensor assembly 4, the housing 7, the seal material 9 and the like are provided with a predetermined mold (not shown). ) And a secondary mold part 10 obtained by injecting a secondary molding resin.

  The air flow rate measuring device 1 takes in a part of the intake air flowing through the intake passage 2 into the internal flow passage 5 and causes the sensor chip 3 to generate a heat transfer phenomenon between the intake air and the intake air mass. An electric signal corresponding to the flow rate (hereinafter sometimes referred to as intake air amount) is generated.

  The sensor assembly 4 includes a sensor chip 3 that generates an electrical signal corresponding to the amount of intake air, a processing unit 13 that performs a predetermined process on the electrical signal generated by the sensor chip 3, and an electrical connection from the processing unit 13 to the outside of the sensor assembly 4. And an assembly terminal 14 for outputting a signal, and the sensor chip 3, the processing unit 13, the assembly terminal 14 and the like are provided by insert molding.

  The sensor assembly 4 is provided in a substantially rectangular plate shape, and the thickness thereof is gradually increased from the front end toward the rear end. Here, the sensor assembly 4 is provided at the front end portion 4a for holding the sensor chip 3, the intermediate portion 4b for holding the connection between the sensor chip 3 and the processing portion 13, and the processing portion provided at the rear end side of the intermediate portion 4b. 13 has a main body portion 4c that holds 13 and increases in thickness in the order of the tip portion 4a, the intermediate portion 4b, and the main body portion 4c.

The distal end portion 4a is provided so as to narrow the spread in the surface direction toward the distal end. The sensor assembly 4 is fitted to the housing 7 so that the tip end portion 4a protrudes into the internal flow path 5, and the sensor chip 3 protrudes so as to be exposed to the internal flow path 5 by the protrusion of the tip end portion 4a. Yes.
The intermediate part 4 b is a part that fits into the fitting hole 6 in each part of the sensor assembly 4.

The main body portion 4 c has a very small portion at the tip end fitted in the fitting hole 6, and a sealing material 9 is mounted around a portion continuous to the rear end side of the portion fitting in the fitting hole 6. Further, a plurality of assembly terminals 14 protrudes in parallel and linearly from the rear end of the main body 4c toward the rear.
The sensor chip 3 and the processing unit 13 have a known function and a known structure.

The housing 7 is a resin molded product, and is provided so that the internal flow path 5 has the following configuration.
That is, the internal flow path 5 is linear from the intake port 16 that opens toward the upstream side of the intake path 2, the intake discharge port 17 that opens toward the downstream side of the intake path 2, and the intake port 16. And a straight path 18 for straightly moving the intake air in the same direction as the main flow of intake air in the intake path 2; And a dust discharge path 20 for discharging dust by linear connection.

  Here, the tip portion 4a of the sensor assembly 4 protrudes in a predetermined arrangement region 19a in the peripheral circuit 19 where the circulating intake air flows in a direction opposite to the main intake air flow. Further, the peripheral circuit 19 is branched into two on the downstream side, and two discharge ports 17 are provided.

  The secondary mold part 10 is obtained by setting the wiring module 23 in a mold together with the sensor assembly 4, the housing 7, the sealing material 9, and the like and injecting a secondary molding resin. Here, the wiring module 23 has a terminal 24a and an assembly for outputting an electrical signal output from the sensor assembly 4 to an electronic control device (hereinafter referred to as ECU: not shown) outside the air flow rate measuring device 1. A terminal 24b is connected to the terminal 14 to receive an electric signal input from the sensor assembly 4, a terminal 24c is used to receive an electric signal input from an intake air temperature sensor (not shown) for detecting the intake air temperature, and the like. .

The wiring module 23 is connected so that the terminal 24 a forms the connector 25, the terminal 24 b is electrically connected to the assembly terminal 14, and the terminal 24 c is exposed to the outside of the air flow measuring device 1. Next, it is molded. In the sensor assembly 4, most of the surface of the main body portion 4 c is covered with the secondary mold portion 10, and the main body portion 4 c and the secondary mold portion 10 are in direct contact to form an interface 26.
The ECU grasps the intake air amount based on the electrical signal obtained from the air flow rate measuring device 1, and executes various control processes such as fuel injection control based on the grasped air intake amount.

  The sealing material 9 is a known adhesive, and is filled so as to surround the vicinity of the tip of the main body portion 4 c in an annular shape so as to seal the gap 8. Here, the gap 8 is mainly formed between the hole surface of the fitting hole 6 and the surface of the intermediate portion 4b. The sealing material 9 surrounds the vicinity of the tip of the main body portion 4c in an annular shape and seals the gap 8, thereby preventing the intake air leaking from the internal flow path 5 into the gap 8 from leaking to the interface 26 and the like. ing.

  The sealing material 9 prevents leakage of the intake air from the gap 8 to the interface 26 and the like, thereby suppressing the moisture contained in the intake air from adhering to the assembly terminal 14 and the terminal 24b. In addition, the moisture adhering to the terminal 24 b is prevented from leaking toward the connector 25 and entering the sensor assembly 4.

  In other words, in the air flow rate measuring device 1, the sealing material 9 prevents leakage of the intake air passing through the internal flow path 5, so that moisture enters an area where electrical conduction exists, such as the assembly terminal 14 and the terminals 24 a and 24 b. , Keeps reliability by suppressing the occurrence of unintended short circuit.

[Features of Example 1]
Features of the air flow rate measuring apparatus 1 according to the first embodiment will be described with reference to FIGS. 1 and 2.
According to the air flow rate measuring device 1, the fitting hole 6 has a straight hole axis so that the sensor assembly 4 can be moved and fitted linearly. That is, the fitting hole 6 is provided so that the tip end portion 4a can protrude into the arrangement region 19a by moving the sensor assembly 4 linearly in one direction.

  The sensor assembly 4 and the housing 7 have engaging portions 4K and 7K that abut against each other and restrict the fitting of the sensor assembly 4 in the fitting hole 6, respectively. Here, the engaging portion 4K is a step portion formed between the intermediate portion 4b and the main body portion 4c in the sensor assembly 4. The engaging portion 7K has a step on the hole surface of the fitting hole 6 at a position slightly closer to the internal flow path 5 than the opening edge 6a of the fitting hole 6, and is extremely narrow from the step to the opening edge 6a. The hole region is provided by enlarging the tip of the main body portion 4c.

The engaging portions 4K and 7K are brought into contact with each other in the direction of the hole axis by fitting into the fitting hole 6 of the sensor assembly 4 and then come into contact with each other to restrict the fitting of the sensor assembly 4.
The engaging portions 4K and 7K have contact surfaces 4A and 7A that come into surface contact with each other at the time of contact. The contact portions 4A and 7A come into contact with each other when they come into surface contact. The contact surface 4A is the front end surface of the engaging portion 4K, and the contact surface 7A is the rear end surface of the engaging portion 7K. Furthermore, the contact surfaces 4A and 7A are both perpendicular to the hole axis.

  Further, the housing 7 has an annular rib 30 that surrounds the opening edge 6 a of the fitting hole 6, and the annular rib 30 is formed by fitting the intermediate portion 4 b of the sensor assembly 4 into the fitting hole 6, whereby the main body portion 4 c. An annular space 32 is formed between the two.

Here, the space 32 is formed by the inner peripheral surface of the annular rib 30, the surface of the main body portion 4 c, and the annular bottom surface 33 that extends between the opening edge 6 a and the annular rib 30. The sealing material 9 is filled so as to accumulate on the bottom surface 33 of the space 32, and the secondary molding resin injected into the mold flows into the space 32 and solidifies while the sealing material 9 accumulates in the space 32. To do. For this reason, the sealing material 9 and the secondary mold part 10 are in direct contact with each other to form an interface.
As described above, the sealing material 9 is arranged on the downstream side of the contact area of the engaging portions 4K and 7K with respect to the flow direction of air leakage from the internal flow path 5 passing through the gap 8.

Further, the rear end surface of the main body portion 4 c is provided in a tapered shape that tapers toward the rear, and the rear end forms a straight ridge line 35. A plurality of assembly terminals 14 protrude in parallel in the direction of the hole axis from the ridge line 35 toward the rear. Of the plurality of assembly terminals 14, one assembly terminal 14 is disposed on the hole axis, and the other assembly terminal 14 is disposed in parallel with the hole axis.
As described above, the rear end surface of the main body 4c is the protruding surface 36 from which the assembly terminal 14 protrudes in the direction of the hole axis.

[Production Method of Example 1]
A method for manufacturing the air flow rate measuring apparatus 1 according to the first embodiment will be described with reference to FIGS.
The manufacturing method of the air flow rate measuring device 1 is that the sensor assembly 4 is moved in the direction of the hole axis of the fitting hole 6 and fitted into the fitting hole 6, whereby the tip portion 4 a having the sensor chip 3 is made into the internal flow path 5. A first preparation step for projecting, a second preparation step for filling and arranging the sealing material 9 around the sensor assembly 4, a sensor assembly 4, a housing 7 and a sealing material constituted by the first preparation step and the second preparation step And a molding step of molding the secondary mold portion 10 by injecting a secondary molding resin.

  In the first preparation step, the sensor assembly 4 is linearly moved in the direction of the hole axis of the fitting hole 6 to be fitted in the fitting hole 6, and the engaging portion 4K is brought into contact with the engaging portion 7K. As a result, the sensor assembly 4 does not fit excessively into the fitting hole 6 and the tip portion 4a protrudes to an appropriate position in the arrangement region 19a. Further, by fitting the sensor assembly 4 into the fitting hole 6, an annular space 32 is formed, and most of the main body portion 4 c is disposed outside the housing 7 (hereinafter, the inside of the sensor assembly 4, The portion arranged outside the housing 7 may be referred to as an outside housing arrangement portion 39).

  In the second preparation step, the bottom surface 33 of the space 32 is filled with the sealing material 9. Thereby, the sealing material 9 is annularly filled around the main body portion 4c and seals the gap 8 from the outside. Further, the sealing material 9 is arranged on the downstream side of the contact area of the engaging portions 4K and 7K with respect to the flow direction of the leakage of the intake air from the internal flow path 5 passing through the gap 8.

  In the molding step, the integrated body 38 is arranged so that the hole axis intersects with the injection port 41 of the secondary molding resin and the outer housing arrangement portion 39 of the sensor assembly 4 faces the injection port 41 in the direction of the hole axis. Set to the mold. In addition, only the projecting surface 36 of the surface of the outer housing arrangement portion 39 directly faces the injection port 41 in the direction of the hole axis.

  Then, the secondary molding resin is injected from the injection port 41 in the direction of the hole axis and collides with the outer casing arrangement portion 39. At this time, the secondary molding resin collides with the projecting surface 36 in the direction of the hole axis, and is equally divided into one end side and the other end side in the thickness direction of the sensor assembly 4 with the ridge line 35 as a boundary. It flows along the surface.

[Effect of Example 1]
According to the manufacturing method of the air flow measuring device 1 of the first embodiment, in the molding process, the hole axis intersects with the injection port 41 of the secondary molding resin, and the outer casing arrangement portion 39 is connected to the injection port 41. The monolith 38 is set in the mold so as to face the direction of the hole axis.
As a result, the secondary molding resin is injected in the direction of the hole axis from the injection port 41 and collides with the outer housing arrangement portion 39 in the direction of the hole axis, and presses the sensor assembly 4 in the direction of the hole axis. The engaging portion 4K of the sensor assembly 4 strongly contacts the engaging portion 7K of the housing 7.

Therefore, the gap 8 formed between the hole surface of the fitting hole 6 and the surface of the sensor assembly 4 is more airtightly sealed in the contact area between the engaging portions 4K and 7K. The prevention of leakage by 9 is strongly assisted by the enhanced contact between the engaging portions 4K and 7K.
As described above, in the air flow rate measuring device 1, the intake air from the internal flow path 5 by the sealing material 9 is not increased without increasing the cost and without causing the secondary molding resin to protrude to the internal flow path 5 side. It can assist in preventing leakage and improve reliability.

Further, in the second preparation step, the sealing material 9 is arranged on the downstream side of the position where the contact regions of the engaging portions 4K and 7K exist with respect to the flow direction of air leakage from the internal flow path 5 passing through the gap 8. To do.
Thereby, when the sealing material 9 flows toward the internal flow path 5 through the gap 8, the seal material 9 reaches the contact area between the engaging portions 4 </ b> K and 7 </ b> K before reaching the internal flow path 5. For this reason, leakage of the sealing material 9 toward the internal flow path 5 can be suppressed by strengthening the contact between the engaging portions 4K and 7K.

In the molding process, the integrated object 38 is set in the mold so that the protruding surface 36 of the assembly terminal 14 faces the injection port 41 in the direction of the hole axis.
As a result, the secondary molding resin flows along the assembly terminal 14 in parallel with the hole axis, so that the assembly terminal 14 can be prevented from falling due to the flow pressure of the secondary molding resin.

Furthermore, the protruding surface 36 is provided in a tapered shape that tapers toward the rear.
Thereby, the secondary molding resin flowing from the injection port 41 collides with the projecting surface 36 in the direction of the hole axis, and reaches the one end side and the other end side in the thickness direction of the sensor assembly 4 with the ridge line 35 as a boundary. It divides equally and flows along the surface of the main body 4c. Therefore, the sensor assembly 4 can be prevented from falling due to the flow pressure of the secondary molding resin.

[Example 2]
According to the air flow rate measuring device 1 of the second embodiment, as shown in FIG. 5, the contact surfaces 4A and 7A included in the engaging portions 4K and 7K are closer to the hole axis as they are closer to the internal flow path 5. It is inclined to.
Thereby, the wedge effect is obtained by the contact between the engaging portions 4K and 7K, and the contact surface 4A comes into stronger contact with the contact surface 7A. For this reason, since the gap 8 can be sealed more airtightly in the contact region between the engaging portions 4K and 7K, the assist of leakage prevention can be further strengthened to improve the reliability of the air flow measuring device 1. it can.

[Modification]
The aspect of the air flow rate measuring device 1 is not limited to the first and second embodiments, and various modifications can be considered.
For example, according to the air flow rate measuring device 1 of the first and second embodiments, the engaging portions 4K and 7K are in contact with each other by the surface contact between the contact surfaces 4A and 7A included in each of the engaging portions 4K and 7K. An annular rib is provided on the rear end surface so as to surround the fitting hole 6, and the annular rib is brought into annular contact with the front end surface of the engaging portion 4K so that the engaging portions 4K and 7K are brought into contact with each other. Also good.

DESCRIPTION OF SYMBOLS 1 Air flow measuring device 3 Sensor chip 4 Sensor assembly 4b Middle part (a part of sensor assembly)
4K engagement part (engagement part of sensor assembly)
4A Contact surface (contact surface on the sensor assembly side)
5 Internal flow path 6 Fitting hole 7 Case 7K Engagement part (engagement part of case)
7A Contact surface (contact surface on the housing side)
8 Clearance 9 Sealing material 10 Secondary mold part 14 Assembly terminal 36 Projection surface (Part of the surface of the sensor assembly facing the injection port and the hole axis)
38 Integral Item 39 Outer Housing Arrangement Section (A portion of the sensor assembly arranged outside the enclosure)
41 Injection port

Claims (6)

A sensor assembly that holds a sensor chip that generates an electrical signal by heat transfer with air;
An internal flow path through which air passes, and a housing having a fitting hole into which a part of the sensor assembly is fitted so that the sensor chip protrudes into the internal flow path;
A sealing material disposed around the sensor assembly and sealing a gap formed between a hole surface of the fitting hole and a surface of the sensor assembly to prevent air from leaking from the internal flow path;
A secondary mold part obtained by setting the sensor assembly, the housing and the sealing material in a predetermined mold and injecting a resin for secondary molding;
The fitting hole has a linear hole axis so that the sensor assembly can move and fit linearly;
The sensor assembly and the housing each have an engaging portion that abuts each other and restricts the fitting of the sensor assembly in the fitting hole,
The engagement portion of the sensor assembly and the engagement portion of the housing come into contact with each other after approaching the direction of the hole axis by fitting the sensor assembly into the fitting hole. An air flow rate measuring device for restricting the fitting of the air. The air flow rate measuring device according to claim 1,
The sealing material is disposed on the downstream side of the position where the engaging portion of the sensor assembly and the engaging portion of the housing are present in the flow direction of air leakage from the internal flow path passing through the gap. An air flow rate measuring device characterized by that. In the air flow rate measuring device according to claim 1 or 2,
The engaging portion of the sensor assembly and the engaging portion of the housing each have a contact surface that comes into surface contact with each other at the time of contact,
The air flow measuring device according to claim 1, wherein the contact surface on the sensor assembly side and the contact surface on the housing side are inclined so as to approach the hole axis as they are closer to the internal flow path. It is a manufacturing method of the air flow measuring device according to any one of claims 1 to 3,
A first preparation step of projecting the sensor chip into the internal flow path by moving the sensor assembly in the direction of the hole axis and fitting it in the fitting hole;
A second preparation step of disposing the sealing material around the sensor assembly;
The sensor assembly constituted by the first preparation step and the second preparation step, the integrated body of the casing and the sealing material is set in the mold, and a secondary molding resin is injected to the secondary mold. A molding process for molding the part,
In the molding step, a portion of the sensor assembly that is disposed outside the housing is arranged so that the hole axis intersects the secondary molding resin injection port, and the injection port and the hole. The method for manufacturing an air flow rate measuring device, wherein the unitary object is set in the mold so as to face the direction of the shaft. In the manufacturing method of the air flow measuring device according to claim 4,
The sensor assembly has a terminal for outputting an electrical signal;
This terminal protrudes from the predetermined protruding surface in the direction of the hole axis,
In the molding step, the one-piece object is set in the mold such that the projecting surface faces the injection port in the direction of the hole axis. In the manufacturing method of the air flow measuring device according to claim 4 or 5,
In the molding step, the integrated object is set in the mold so that a part of the surface of the sensor assembly is opposed to the injection port in the direction of the hole axis,
A portion of the surface of the sensor assembly facing the injection port in the direction of the hole axis is provided in a tapered shape that tapers toward the injection port. Method.

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