Sensor unit and throttle device provided with same

Abstract

Provided is a sensor unit in which a sensor is embedded with a sealing resin in a filling recess of a unit case, and in which defoaming traces can be prevented from occurring on the surface of a sealing resin filling section formed from the cured sealing resin. This sensor unit is provided with: a synthetic resin unit case (10) which is injection-molded using a sensor (14) positioned by a plurality of claw sections (24d) provided in a mold (21) as an insert, and which includes a plurality of claw recesses (26b) and a filling recess (16), and which is formed from a synthetic resin in which the plurality of claw recesses (26b) and the filling recess (16) are filled in the claw sections (24d) in a planar view as viewed from the mold release direction of the respective claw sections (24d); the plurality of claw recesses are arranged around the sensor (14) in a posture in which the inner ends of the claw recesses are in contact with the outer peripheral surface of the sensor (14), and fill the openings of the recesses in the mold release direction; and a sealing resin filling part (17) which is formed in the filling recess (16) by means of a sealing resin and in which the sensor (14) and the claw recesses (26b) are embedded. Each of the claw recesses (26b) has a shape in which the width becomes narrower toward the inner end in plan view, and a closed region (27) is formed on both sides of each of the inner ends by means of a synthetic resin that forms the unit case (10).

Description

Technical Field

[0001] The present invention relates to a sensor unit and a throttle device including the sensor unit. Background Art

[0002] Conventionally, as a sensor unit included in a throttle device, for example, Patent Document 1 discloses a pressure detection device that detects an intake pressure flowing in an intake passage of a throttle body. A housing of the pressure detection device is attached to the throttle body. In a filling recess formed in the housing, a pressure introduction passage communicating with the intake passage is provided, and a circuit board and a pressure detection element are disposed. For the filling recess, a cover is attached from above, and a sealing resin is filled. The sealing resin is injected and cured in the filling recess to bury the circuit board and the pressure detection element. Thus, while protecting the circuit board and the pressure detection element, the intake pressure can be detected by the pressure detection element via the pressure introduction passage. Prior Art Documents Patent Documents

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-28797 Summary of the Invention Technical Problem to be Solved by the Invention

[0004] In the technique of Patent Document 1, when the sealing resin is filled, air bubbles sometimes occur in the sealing resin injected into the filling recess. The above phenomenon becomes more significant, for example, when vacuum is applied to spread the sealing resin throughout the filling recess or when heating is performed to promote curing of the resin after injection. The generated air bubbles float in the sealing resin, and sometimes defoaming marks are generated on the surface of the sealing resin filling portion formed by the cured sealing resin. The above defoaming marks are not ideal in terms of the appearance of the product. Therefore, a countermeasure has been desired in the past.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a sensor unit and a throttle device including the sensor unit, in which the sensor unit is configured to be buried with a sealing resin in a filling recess formed in a unit housing, and a situation where defoaming marks are generated on the surface of the sealing resin filling portion formed by the cured sealing resin can be prevented, thereby improving the appearance of the product. Technical Solution for Solving the Technical Problem

[0006] To achieve the above object, the sensor unit of the present invention includes: a unit housing which is a synthetic resin unit housing formed by injection molding with a sensor positioned by a plurality of claw portions provided on a mold as an insert, and includes a plurality of claw recesses and a filling recess. When viewed from above in the demolding direction of each claw portion, the plurality of claw recesses are disposed around the sensor in a posture where their inner ends are in contact with the outer peripheral surface of the sensor, and the filling recess is formed to open in the demolding direction of the sensor and each claw recess; and a sealing resin filling portion which is formed in the filling recess by a sealing resin to bury the sensor and each claw recess. Each claw recess has a shape where the width becomes narrower toward the inner end when viewed from above, and closed regions are formed by the synthetic resin forming the unit housing on both sides of the inner end of each claw recess when viewed from above.

[0007] As another form, it may be that each claw recess has a shape that narrows in an arc shape toward the inner end when viewed from above.

[0008] As another form, it may be that each claw recess has a shape that narrows in a tapered shape toward the inner end when viewed from above.

[0009] As another form, it may be that the sensor is an intake air pressure sensor that detects the pressure of the intake air supplied to the engine.

[0010] As another form, it may be a throttle device that is installed in the engine and includes the above sensor unit. Advantages of the Invention

[0011] According to the present invention, it is possible to provide a sensor unit and a throttle device including the sensor unit, in which the sensor unit is structured such that the sensor is buried in a filling recess formed in the unit housing with a sealing resin, and it is possible to prevent a situation where air bubbles are left on the surface of the sealing resin filling portion formed by the cured sealing resin, thereby improving the appearance of the product. Description of the Drawings

[0012] Figure 1 is a perspective view showing a throttle device including the sensor unit of the embodiment. Figure 2 is an exploded perspective view of separating the sensor unit from the throttle device. Figure 3 is a perspective view showing the sensor unit with the upper surface facing upward during injection molding. Figure 4 is a perspective view showing the sensor unit with the upper surface facing upward during filling. Figure 5 is a perspective view corresponding to Figure 4 without showing the sealing resin filling portion. Figure 6is a perspective view corresponding to separating the circuit board from the sensor unit without showing the sealing resin filling part and Figure 4 the corresponding perspective view. Figure 7 is a perspective sectional view corresponding to line VII-VII of Figure 5 the corresponding sectional perspective view. Figure 8 is an exploded perspective view showing the structure of the mold for injection molding the unit housing. Figure 9 is a perspective view showing the upper part of the positioning insert inserted into the fitting hole. Figure 10 is a top view showing the relationship between the upper part of the positioning insert inserted into the fitting hole and the sensor body. Figure 11 is a perspective view showing the upper part of the positioning insert when inserted into the fitting hole. Figure 12 is a magnified sectional view showing the intake pressure sensor and the positioning insert corresponding to line XII-XII of Figure 10 the corresponding sectional view. Figure 13 is a perspective view showing the relationship between the lower mold and the insert. Figure 14 is a perspective view showing the state where the insert is arranged on the lower mold. Figure 15 is a perspective view showing the state where the connector insert is arranged on the lower mold. Figure 16 is a perspective view showing the mold closed state. Figure 17 is corresponding to Figure 6 a magnified top view of the concave trace corresponding to part A. Figure 18 is corresponding to Figure 7 a magnified sectional perspective view of the concave trace corresponding to part B. Figure 19 is a top view showing the comparative example of the prior art corresponding to Figure 10 the corresponding top view. Figure 20 is also showing the comparative example corresponding to Figure 11 the corresponding perspective view. Figure 21 is also showing the comparative example corresponding to Figure 17 the corresponding magnified top view. Figure 22 is also showing the comparative example corresponding to Figure 18 the corresponding magnified sectional perspective view. Figure 23 is a magnified top view showing another example 1 corresponding to Figure 17 the corresponding top view. Figure 24 is an enlarged top view corresponding to another Example 2 Figure 17 Figure 25 is an enlarged top view corresponding to another Example 3 Figure 17 Figure 26 is an enlarged top view corresponding to another Example 4 Figure 17 DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of a sensor unit obtained by embodying the present invention and a throttle device including the sensor unit will be described. <Overall Structure of Throttle Device> Figure 1 is a perspective view showing a throttle device including the sensor unit of the present embodiment, Figure 2 is an exploded perspective view showing the separation of the sensor unit from the throttle device.

[0014] The throttle device 1 of the present embodiment is installed on a single-cylinder engine of a bicycle equipped with a prime mover, and a single throttle hole 2a is formed through the throttle body 2. In the installed state on the engine, the throttle hole 2a communicates with the inside of the cylinder of the engine, and intake air from an air cleaner (not shown) flows through the throttle hole 2a and is supplied to the cylinder.

[0015] The throttle valve 3 is supported in the throttle hole 2a by a throttle shaft 4 so as to be openable and closable, Figure 1 , Figure 2 The left end of the throttle shaft 4 of is projected outward from the throttle body and a wire reel 5 is installed thereon, and a return spring 6 applies a force in the closing direction of the throttle valve 3. Although not shown, a throttle grip of the vehicle is connected to the wire reel 5 via a throttle wire, and the throttle shaft 4 and the wire reel 5 rotate in conjunction with the operation of the throttle grip to open and close the throttle valve 3, thereby adjusting the intake air amount of the engine.

[0016] The sensor unit 8 is attached to the right side surface of the throttle body 2 by screws 7. By this sensor unit 8, the opening degree of the throttle valve 3, the temperature of the intake air flowing in the throttle body 2a, and the pressure of the intake air are detected. A wire harness from an ECU (engine control unit) installed in the vehicle is connected to a connector 8a provided in the sensor unit 8. Detection signals related to the throttle opening degree, the intake air temperature, and the intake air pressure output from the sensor unit 8 are input to the ECU, and based on this, the operation state of the engine is controlled by the ECU. In addition, a wire harness from the ECU is also connected to a connector 9a of an idle speed control valve (ISCV) 9 attached to the throttle body 2 to control the idle speed. Hereinafter, details of the sensor unit 8 will be described.

[0017] ​​​<Structure of Sensor Unit 8> Figure 3 FIG. 3 is a perspective view showing the sensor unit 8, Figure 4 and FIG. 4 is a perspective view showing the sensor unit 8 in a posture where it is turned over forward and backward relative to Figure 3 FIG. 3. The sensor unit 8 is manufactured in the order of the injection molding unit housing 10 and molding the sealing resin layer by filling the sealing resin. Details will be described below. Figure 3 In FIG. 5, the unit housing 10 is shown in a posture where the mounting surface mounted on the throttle body 2 faces upward, and the injection molding of the unit housing 10 is performed in this posture. Hereinafter, the upper surface of the unit housing 10 at this time is referred to as the upper surface Fa during injection molding. In addition, Figure 4 in FIG. 6, the unit housing 10 is shown in a posture where the surface opposite to the unit housing 10 faces upward, and the filling of the sealing resin is performed in this posture. Hereinafter, the upper surface of the unit housing 10 at this time is referred to as the upper surface Fb during filling.

[0018] As shown in Figure 3 FIG. 7, the unit housing 10 is manufactured by injection molding a synthetic resin, and an annular fitting portion 10a is integrally formed on the upper surface Fa during injection molding thereof. The unit housing 10 is mounted by screws 7 in a state where the annular fitting portion 10a is fitted into an unillustrated fitting hole on the throttle body 2 side. In addition, 11 is a metal collar through which the screw 7 is inserted, and is respectively embedded in the unit housing 10.

[0019] Inside the annular fitting portion 10a, the cylindrical portion 12a of the throttle opening sensor 12 is fitted. As will be described later, the three terminals 12b of the magnetic field change detection portion 12c ( Figure 6 shown in FIG. 8) provided in the cylindrical portion 12a face Figure 3 downward in FIG. 9, in other words, toward the upper surface Fb during filling. Although not shown, a cylindrical magnetic field generation portion is fixed to the right end of the throttle shaft 4 on the throttle body 2 side. In a state where the sensor unit 8 is mounted on the throttle body 2, a magnetic throttle opening sensor 12 is constituted by the cylindrical portion 12a, the magnetic field change detection portion 12c, and the magnetic field generation portion. Therefore, when the magnetic field generation portion rotates together with the throttle shaft 4, a signal corresponding to its rotation angle is output from the throttle opening sensor 12.

[0020] In addition, a detection piece 10b is integrally formed on the upper surface Fa during injection molding of the unit housing 10 and extends upward toward Figure 3 FIG. 9. As shown by the dashed line in the figure, the sensor main body 13a of the intake air temperature sensor 13 is disposed at the front end inside the detection piece 10b, and from the sensor main body 13a toward Figure 3Two terminals 13b are provided extending downward therein. Then, an intake air temperature sensor 13 is formed by filling the detection member 10b with a sealing resin. In a state where the sensor unit 8 is mounted to the throttle body 2, the front end of the detection member 10b protrudes to an upstream side of the throttle valve 3 in the throttle hole 2a. Therefore, the sensor body 13a is exposed to the intake air flowing in the throttle hole 2a, and a signal corresponding to the intake air temperature is output.

[0021] In addition, a pressure chamber 10c is recessed in the upper surface Fa during injection molding of the unit housing 10, and a pressure housing 14c having a detection hole 14d in the center is exposed in the pressure chamber 10c. As described later, the sensor body 14a is connected overlappingly with the lower side of the pressure housing 14c embedded in the unit housing 10. Three terminals 14b extend downward from the sensor body 14a, whereby an intake air pressure sensor 14 is formed. Figure 3

[0022] In a state where the sensor unit 8 is mounted to the throttle body 2, the pressure chamber 10c communicates with a position on the downstream side of the throttle valve 3 in the throttle hole 2a via a pressure passage (not shown) formed in the throttle body 2. Therefore, the pressure of the intake air flowing in the throttle hole 2a acts on the sensor body 14a via the pressure passage, the pressure chamber 10c, the detection hole 14d, and the inside of the pressure housing 14c, and thus a signal corresponding to the intake air pressure is output from the sensor body 14a.

[0023] Figure 5 is a perspective view corresponding to Figure 4 without showing the sealing resin filling portion, Figure 6 is a perspective view corresponding to Figure 4 without showing the sealing resin filling portion and separating the circuit board from the sensor unit 8, Figure 7 is a cross-sectional perspective view corresponding to the VII-VII line of Figure 5 .

[0024] As Figure 4 shown, on the upper surface Fb during filling of the unit housing 10, an annular filling recess 16 surrounding most of its area is formed to open in the demolding direction described later, and a sealing resin filling portion 17 is formed and filled inside. By filling with the sealing resin, the sealing resin is injected and cured in the filling recess 16 to form the sealing resin filling portion 17. As the sealing resin, for example, a thermosetting synthetic resin material such as epoxy resin or a photocurable synthetic resin material is used.

[0025] As Figure 5 , Figure 6As shown, the respective terminals 12b, 13b, and 14b of the throttle opening degree sensor 12, intake air temperature sensor 13, and intake air pressure sensor 14 project from the bottom wall of the filling recess 16, and are respectively inserted and soldered into the through holes 18a of the circuit board 18 arranged from above. In addition, the base ends of the connector terminals 19 are respectively inserted and soldered into five through holes 18b of the circuit board 18, as Figure 7 shown, each connector terminal 19 passes through the unit housing 10 and projects into the connector 8a. As a result, the detection signals output from the respective sensors 12 to 14 are input to the in-vehicle ECU via the circuit board 18 and the connector 8a as described above.

[0026] The above-mentioned circuit board 18, the respective terminals 12b, 13b, 14b, and 19 are embedded in the sealing resin filling portion 17 for protection, and the upper surface Fb during filling of the sensor unit 8 is formed on the surface of the sealing resin filling portion 17. Therefore, the state of the surface of the sealing resin filling portion 17 affects the appearance of the sensor unit 8, and further affects the appearance of the throttle device 1.

[0027] Moreover, during the injection molding of the unit housing 10, the intake air pressure sensor 14 is positioned by the claw portion 24d of the mold 21. Sometimes, a fine gap is generated between the outer peripheral surface of the intake air pressure sensor 14 and the unit housing 10 at the portion of the concave trace 26 generated by the demolding of the claw portion 24d. The details will be described later. Then, during the sealing resin filling performed, air bubbles remaining on the outer peripheral surface of the sensor body 14a of the intake air pressure sensor 14 and the like sometimes mix into the sealing resin injected into the filling recess 16 via the above-mentioned gap. The above-mentioned air bubbles float in the sealing resin, as Figure 4 shown, and remain as defoaming traces P on the surface of the sealing resin filling portion 17 formed by the cured sealing resin, thus affecting the appearance of the sensor unit 8.

[0028] In view of the above-mentioned problems, in the present embodiment, countermeasures are taken for the claw portion 24d that positions the intake air pressure sensor 14. Therefore, focusing on the positioning of the intake air pressure sensor 14, the steps of injection molding the unit housing 10 will be described below.

[0029] <Steps of injection molding the unit housing 10> Figure 8 is an exploded perspective view showing the structure of the mold for injection molding the unit housing 10, Figure 9 is a perspective view showing the upper part of the positioning insert inserted and arranged in the fitting hole, Figure 10 is a top view showing the relationship between the upper part of the positioning insert inserted and arranged in the fitting hole and the sensor body 14a, Figure 11 is a perspective view showing the upper part of the positioning insert when inserted and arranged in the fitting hole,Figure 12 The intake pressure sensor 14 and the positioning insert are shown. Figure 10 An enlarged cross-sectional view corresponding to line XII-XII, Figure 13 This is a perspective view showing the relationship between the lower mold and the embedded product. Figure 14 This is a perspective view showing a state where the insert is arranged on the lower mold. Figure 15 1 is a perspective view showing a state where a connector insert is arranged on a lower mold. Figure 16 It is a perspective view showing the mold clamping state.

[0030] like Figure 8 As shown, the mold 21 is composed of a lower mold 22 and an upper mold 23, which are equivalent to the mother mold, as well as a positioning insert 24 and a connector molding insert 25. The upper surface of the lower mold 22 is formed into a shape corresponding to the upper surface Fb of the unit case 10 during filling. Although not shown, the lower surface of the upper mold is formed into a shape corresponding to the upper surface Fa during injection molding. Figure 16 Therefore, when the molten resin is injected into the cavity, the upper surface Fa is directed upward during injection. Figure 3 The unit case 10 is molded in the posture shown. The posture of the unit case 10 during the above molding is determined so that the terminals 12b, 13b, 14b, and 19 are positioned downward and arranged on the lower mold 22.

[0031] The steps of injection molding are described in detail below in conjunction with the structure of the mold 21 . Figure 10 、 Figure 11 In the figure, the sensor body 14a of the intake air pressure sensor 14, which is an embedded part, is shown by two-dot chain lines. A fitting hole 22a is vertically penetrated directly below the position where the sensor body 14a is embedded in the lower mold 22. A positioning insert 24 can be inserted into the fitting hole 22a from below. When inserted, the upper end of the positioning insert 24 protrudes from the upper surface of the lower mold 22 into the cavity, thereby positioning the intake air pressure sensor 14.

[0032] like Figure 12 As shown in FIG. 1 , the intake pressure sensor 14 is connected in a state where the pressure housing 14c is overlapped on the upper side of the sensor body 14a. Figure 10 When viewed from above, the lower surface of the sensor body 14a appears to be a plane formed by cutting a portion of a circle into a straight line. The three terminals 14b bend downward from this straight line. When the intake pressure sensor 14 is positioned on the lower mold 22, each terminal 14b is inserted into a terminal hole 22b formed in the lower mold 22.

[0033] likeFigure 9 As shown, the upper end surface 24a of the positioning insert 24 is also a flat surface having a shape corresponding to the lower surface of the sensor body 14a, and substantially equally divided three portions on the outer periphery expand outward in a square shape toward the outer periphery. On each of the thus formed expansion portions 24b, positioning claw portions 24d project upward via tapered surfaces 24c facing three directions. The inner ends of the respective claw portions 24d, specifically, the ends facing the center side of the sensor body 14a in the top view shown, are respectively in contact with the outer peripheral surface of the sensor body 14a. By inserting the terminals 14b into the respective terminal holes 22b, together with restricting the rotation of the sensor body 14a, the sensor body 14a is positioned in the top view. Further, the lower surface of the sensor body 14a is in contact with the upper end surface 24a of the positioning insert 24, thereby positioning the sensor body 14a in the vertical direction. Thus, the sensor body 14a and the pressure housing 14c connected to the sensor body 14a are held at a specified position in the cavity of the mold 21. Figure 10 As shown, the upper end surface 24a of the positioning insert 24 is also a flat surface having a shape corresponding to the lower surface of the sensor body 14a, and substantially equally divided three portions on the outer periphery expand outward in a square shape toward the outer periphery. On each of the thus formed expansion portions 24b, positioning claw portions 24d project upward via tapered surfaces 24c facing three directions. The inner ends of the respective claw portions 24d, specifically, the ends facing the center side of the sensor body 14a in the top view shown, are respectively in contact with the outer peripheral surface of the sensor body 14a. By inserting the terminals 14b into the respective terminal holes 22b, together with restricting the rotation of the sensor body 14a, the sensor body 14a is positioned in the top view. Further, the lower surface of the sensor body 14a is in contact with the upper end surface 24a of the positioning insert 24, thereby positioning the sensor body 14a in the vertical direction. Thus, the sensor body 14a and the pressure housing 14c connected to the sensor body 14a are held at a specified position in the cavity of the mold 21.

[0034] In addition, as Figure 1 shown, the corner portion 14e between the lower surface and the outer peripheral surface of the sensor body 14a is rounded. Therefore, the substantially vertical contact area between the inner end of the claw portion 24d and the outer peripheral surface of the sensor body 14a is dimension L.

[0035] As ​ shown, as inserts other than the intake pressure sensor 14, there are a cylindrical portion 12a of the throttle opening sensor 12, a connector terminal 19, and a collar 11. These inserts are not directly related to the gist of the present invention, and thus will be only roughly described. However, as ​ shown, they are respectively arranged at specified positions on the lower mold 22. Next, as ​ shown, a connector molding insert 25 is arranged on the lower mold 22. On the basis of closing the mold as ​ shown, after injecting molten resin into the cavity, the unit housing 10 is formed in the attitude as ​ shown.

[0036] Next, when the unit housing 10 is turned over front to back, as ​ 、 ​As shown, the upper surface Fb faces upward during filling. On the upper surface Fb during filling, the base ends of the terminals 14b of the intake pressure sensor 14 and the connector terminals 19 protrude upward, and the interiors of the cylindrical portion 12a of the throttle opening sensor 12 and the detection member 10b of the intake air temperature sensor 13 are open upward. Furthermore, the sensor body 14a of the intake pressure sensor 14 is exposed, and as the claws 24d of the positioning insert 24 are demolded, concave marks 26 are formed at three locations around the sensor body 14a. Each concave mark 26 mimics the shape of the tapered surface 24c and claws 24d of the positioning insert 24 and is arranged to surround the sensor body 14a with its inner end in contact with the outer peripheral surface of the sensor body 14a.

[0037] The filling recess 16 is opened upward while surrounding the above-mentioned parts. In order to embed the above-mentioned parts with the sealing resin filling portion 17, sealing resin filling is performed as the next step.

[0038] <Sealing Resin Filling Step> First, before the sealing resin is filled, ​ 、 ​ As shown, the terminals 13b of the intake air temperature sensor 13 and the terminals 12b of the throttle opening sensor 12 are pre-inserted and soldered into the through-holes 18a of the circuit board 18. The sensor body 13a is supported by the lower end of the downwardly extending terminals 13b. Similarly, the magnetic field change detector 12c is supported by the lower end of the downwardly extending terminals 12b. When the circuit board 18 is positioned at a predetermined position on the unit housing 10, the sensor body 13a and terminals 13b of the intake air temperature sensor 13 are inserted into the interior of the detector 10b, and the magnetic field change detector 12c of the throttle opening sensor 12 is positioned within the cylindrical portion 12a. Simultaneously, the base ends of the terminals 14b of the intake air pressure sensor 14 and the connector terminals 19 protrude upward through the through-holes 18a and 18b of the circuit board 18.

[0039] After protruding terminals 14b and 19 are inserted into through-holes 18a and 18b of circuit board 18 and soldered, sealing resin is injected into filling recess 16. The sealing resin penetrates into detection element 10b and completely fills filling recess 16 while impregnating circuit board 18, terminals 12b, 14b, 19, and concave marks 26 around sensor body 14a. After curing, sealing resin filler 17 is formed, embedding circuit board 18, terminals 12b, 13b, 14b, 19, and the like therein. This completes the manufacture of sensor unit 8.

[0040] <Behavior of bubbles during sealing resin filling> Between the unit housing 10 after injection molding, specifically, the resin forming the unit housing 10 and the cylindrical portion 12a of the throttle opening sensor 12 and the intake pressure sensor 14 embedded therein, air bubbles may remain due to various factors. For example, consider the following situations: Air accumulates inside the intake pressure sensor 14 with a hollow interior, and a part of it leaks to the outside through the gap between the sensor body 14a and the pressure housing 14c during injection molding and remains as air bubbles on the outer peripheral surface of the sensor body 14a. Even if the above air bubbles remain, due to the close contact between the surfaces of the respective sensors 12 and 14 and the unit housing 10, the air bubbles are not easily penetrated. Therefore, the possibility of air bubbles mixing into the sealing resin injected into the filling recess 16 during sealing resin filling is low.

[0041] However, during injection molding, the intake pressure sensor 14 is positioned by the claw portion 24d. As described based on ​ , ​ , concave traces 26 are formed at three locations around the sensor body 14a along with the demolding of the claw portion 24d. Therefore, at the locations of the concave traces 26, the outer peripheral surface of the sensor body 14a is exposed, and thus air bubbles from below are likely to pass upward through the concave traces 26 and may mix into the sealing resin.

[0042] <Detailed shape of the concave trace 26 for truncating air bubbles> ​ is an enlarged top view of the concave trace 26 corresponding to part A of ​ , ​ is an enlarged cross-sectional perspective view of the concave trace 26 corresponding to part B of ​ . The concave traces 26 at the other two locations are also of the same shape. Hereinafter, based on these figures and ​ , ​ showing the claw portion 24d during injection molding, countermeasures for preventing air bubbles from passing through the concave trace 26 will be described.

[0043] To put it simply, the countermeasure of the present embodiment is as follows: The contact area between the inner end of the claw portion 24d and the outer peripheral surface of the sensor body 14a is reduced, and the molten resin during injection molding is spread over the reduced area, thereby forming the following closed area 27. Through this closed area 27, the cross-sectional area of the gap through which air bubbles pass from bottom to top is reduced to seek to truncate the air bubbles.

[0044] For this purpose, as shown in ​ , 11 , half of the area on the inner end side of each claw portion 24d is shaped to narrow inward in an arc shape when viewed from above, and as a result, a point at the inner end abuts against the outer peripheral surface of the sensor body 14a. And as shown in ​As shown, a draft angle that gradually tapers downward and slightly reduces the diameter is set on the outer peripheral surface of the sensor main body 14a. Correspondingly, the inner ends of the respective claw portions 24d are also slightly tapered, but have substantially the same cross-sectional shape at any position in the vertical direction, and they abut against each other at one point. As a result, the inner ends of the claw portions 24d are in line contact with the outer peripheral surface of the sensor main body 14a.

[0045] The molten resin is injected into the cavity of the mold 21 with the above mutual relationship to form the unit housing 10. After the respective claw portions 24d are demolded, a ​ 、 ​ concave trace 26 of the shape shown is formed around the sensor main body 14a. That is, as ​ shown, on each expanding portion 24b of the positioning insert 24, a shape is formed in which the claw portion 24d protrudes upward via a tapered surface 24c facing three directions. Therefore, as ​ 、 ​ shown, the concave trace 26 has the following shape: when viewed from above in the demolding direction of each claw portion 24d, a tapered concave portion 26a having a shape traced from the three tapered surfaces 24c is recessed, and a claw concave portion 26b having a shape traced from the claw portion 24d is further recessed in the center.

[0046] Moreover, since the inner end of the claw portion 24d is circular when viewed from above, two spaces shown by the shaded lines in ​ 、 ​ are formed between the inner end of the claw portion 24d and the outer peripheral surface of the sensor main body 14a. And when injection molding, the molten resin spreads over each space and solidifies. Thus, the claw concave portion 26b is formed into a shape with a circular inner end. Hereinafter, the spaces over which the molten resin spreads are referred to as closed regions 27. By forming the closed regions 27, a narrow region at a point on the outer peripheral surface of the sensor main body 14a where the inner end of the claw portion 24d abuts is partially exposed into the claw concave portion 26b, but most of the regions on both sides thereof are covered by the closed regions 27.

[0047] In addition, the molten resin also spreads over ​ the rounded corner portion 14e of the sensor main body 14a shown and solidifies. Therefore, the length of the substantially closed region 27 in the vertical direction is the length shown by the dimension L in ​ . And directly below the claw concave portion 26b, as shown by the dashed line in ​ the outer peripheral surface of the sensor main body 14a contacts the unit housing 10. When the sealing resin is filled, there is room for air bubbles from below to pass upward between the two, but the above-mentioned air bubbles are blocked by the closed region 27 located directly above.

[0048] Incidentally, for the sake of caution, the important points of this embodiment are as follows: During injection molding, two spaces are intentionally formed between the inner ends of the claw portions 24d and the outer peripheral surface of the sensor body 14a, and the molten resin is spread over each space to form a closed area 27. Through this closed area 27, the air bubbles that are the main cause of the degassing marks P during the subsequent sealing resin filling are cut off. In the conventional sealing resin filling, when burying components such as sensors in a housing, sometimes, in order to spread the injected sealing resin over the entire inside of the housing, a space is intentionally formed between the inner wall of the housing and the component. However, the space intentionally formed by the known technique is used to improve the flow of the sealing resin during the sealing resin filling. In contrast, the intentionally formed space in this embodiment is used to form a closed area 27 by the molten resin during injection molding, and their purposes and the molding contents as the application objects are significantly different. In addition, the sealing resin cured in the space in the known technique does not perform a special function. In contrast, the closed area 27 formed by the molten resin in this embodiment plays an important function of cutting off air bubbles during the sealing resin filling in the subsequent process, which is also significantly different.

[0049] <Comparison between this embodiment and the prior art> Regarding the claw portion 24d of the above embodiment, generally considered ​ 、 ​ The claw portion 124d having the shape shown is formed on the unit housing 10 after demolding ​ The concave trace 126 having the shape shown. Hereinafter, these claw portions 124d and concave traces 126 are regarded as the prior art and compared with this embodiment.

[0050] ​ is a top view showing a comparative example of the prior art corresponding to ​ 、 ​ is a perspective view similarly showing the comparative example corresponding to ​ 、 ​ is a magnified top view similarly showing the comparative example corresponding to ​ 、 ​ is a magnified cross-sectional perspective view similarly showing the comparative example corresponding to ​ 、 Considering the function of the claw portion for positioning the sensor body 14a, in the general concept, as ​ 、 ​ shown, each claw portion 124d is configured to be square-shaped in a top view, and the planes corresponding to their inner ends are respectively in contact with the outer peripheral surface of the sensor body 14a. In addition, the shape of the tapered surface 24c facing three directions is the same as that of the embodiment.

[0051] Therefore, in the state where the sensor main body 14a is positioned, the outer peripheral surface of the sensor main body 14a and the inner end of the claw portion 124d are in a relationship of close surface contact, and only a fine gap is formed therebetween. Specifically, a gap is formed that is so fine that there is no room for molten resin with a certain degree of viscosity to penetrate. Therefore, during injection molding, the molten resin does not spread into the gap. After demolding, a claw recess 126b without a closed area 27 as shown in ​ and ​ is formed, and most of the area of the outer peripheral surface of the sensor main body 14a that has been contacted by the inner end of the claw portion 124d is exposed within the claw recess 126b. ​ 、 ​ Then, when the sealing resin is filled, in the case of the comparative example, as shown by the dotted arrow in and

[0052] , the air bubbles remaining on the outer peripheral surface of the sensor main body 14a and the like during injection molding will float up and reach the claw recess 126b. The claw recess 126b does not have a closed area 27, and the viscosity of the air bubbles is lower than that of the molten resin. Therefore, as shown by the solid arrow, the air bubbles easily pass through the gap and mix into the sealing resin, and then float up in the sealing resin. As a result, the air bubbles remain as degassing traces P on the surface of the cured sealing resin filling portion 17, which becomes the main reason for damaging the appearance of the sensor unit 8.

[0052] During the sealing resin filling, sometimes vacuum is applied to make the sealing resin cover the entire filling recess 16, or heating is performed to promote the curing of the resin after injection. Under these conditions, the generation of air bubbles is particularly significant. In addition, when resin materials with different linear expansion coefficients are applied to the unit housing 10 and the sensor main body 14a, along with the expansion of the gap caused by heating, the air bubbles are likely to pass through. The comparative example is easily affected by the above conditions, and when all the conditions are met, the generation of the degassing trace P becomes significant. ​ In contrast, in the present embodiment, as shown by the dotted arrow in and

[0053] , most of the air bubbles reaching the claw recess 26b are intercepted by the closed area 27, preventing them from mixing into the sealing resin in the filling recess 16. A narrow area of a point on the outer peripheral surface of the sensor main body 14a where the inner end of the claw portion 24d abuts is exposed into the claw recess 26b. Therefore, although it is also possible for air bubbles to pass through, compared with the comparative example, the cross-sectional area of the gap is small, so only a very small amount of air bubbles pass through. In addition, even if the above conditions for the sealing resin filling where air bubbles are likely to be generated or the conditions related to the resin material with different linear expansion coefficients are met, the cross-sectional area of the original gap is small, so the passage of air bubbles can be prevented. Therefore, the degassing trace P generated on the surface of the sealing resin filling portion 17 can be prevented, and the appearance of the sensor unit 8 is not damaged.

[0053] In the sealing resin filling, sometimes vacuum is applied to make the sealing resin cover the entire filling recess 16, or heating is performed to promote the curing of the resin after injection. Under these conditions, the generation of air bubbles is particularly significant. In addition, when resin materials with different linear expansion coefficients are applied to the unit housing 10 and the sensor main body 14a, along with the expansion of the gap caused by heating, the air bubbles are likely to pass through. The comparative example is easily affected by the above conditions, and when all the conditions are met, the generation of the degassing trace P becomes significant.

[0054] In contrast, in the present embodiment, as shown by the dotted arrow in ​ , most of the air bubbles reaching the claw recess 26b are intercepted by the closed area 27, preventing them from mixing into the sealing resin in the filling recess 16. A narrow area of a point on the outer peripheral surface of the sensor main body 14a where the inner end of the claw portion 24d abuts is exposed into the claw recess 26b. Therefore, although it is also possible for air bubbles to pass through, compared with the comparative example, the cross-sectional area of the gap is small, so only a very small amount of air bubbles pass through. In addition, even if the above conditions for the sealing resin filling where air bubbles are likely to be generated or the conditions related to the resin material with different linear expansion coefficients are met, the cross-sectional area of the original gap is small, so the passage of air bubbles can be prevented. Therefore, the degassing trace P generated on the surface of the sealing resin filling portion 17 can be prevented, and the appearance of the sensor unit 8 is not damaged. ​ In contrast, in the present embodiment, as shown by the dotted arrow in ​ , most of the air bubbles reaching the claw recess 26b are intercepted by the closed area 27, preventing them from mixing into the sealing resin in the filling recess 16. A narrow area of a point on the outer peripheral surface of the sensor main body 14a where the inner end of the claw portion 24d abuts is exposed into the claw recess 26b. Therefore, although it is also possible for air bubbles to pass through, compared with the comparative example, the cross-sectional area of the gap is small, so only a very small amount of air bubbles pass through. In addition, even if the above conditions for the sealing resin filling where air bubbles are likely to be generated or the conditions related to the resin material with different linear expansion coefficients are met, the cross-sectional area of the original gap is small, so the passage of air bubbles can be prevented. Therefore, the degassing trace P generated on the surface of the sealing resin filling portion 17 can be prevented, and the appearance of the sensor unit 8 is not damaged.

[0055] As a result, according to the present embodiment, on the basis of being configured to embed the intake pressure sensor 14 positioned in the filling recess 16 formed in the unit housing 10 with a sealing resin, it is possible to prevent the occurrence of a defoaming mark P on the surface of the sealing resin filling portion 17 formed by the cured sealing resin, thereby improving the appearance of the product.

[0056] As described above, the gist of the present invention is to reduce the contact area between the inner end of the claw portion 24d and the outer peripheral surface of the sensor main body 14a, and to spread the molten resin during injection molding over the reduced space to form a closed area 27, thereby cutting off air bubbles. For this purpose, the claw recess 26b of the concave mark 26 needs to be shaped such that the width becomes narrower toward the inner end when viewed from above. In other words, as ​ shown, if the width dimension Lin of the inner end of the claw recess 26b in the circumferential direction of the sensor main body 14a is set to be smaller than the maximum width dimension Lout of other portions including the outer peripheral end, the desired function can be achieved. Hereinafter, as a modified example satisfying this condition, another example 1 to 4 will be described.

[0057] [Another Example 1] As ​ shown, the claw recess 226b of the concave mark 226 of this another example 1 is shaped to taper inwardly toward the inner end when viewed from above. Specifically, half of the inner end side region of the claw recess 226b is rectangular when viewed from above, and the inner end forms an angle and is in line contact with the outer peripheral surface of the sensor main body 14a, and has substantially the same cross-sectional shape in the vertical direction. Although not shown, the shape of the claw recess 226b is formed using a claw portion having a corresponding shape, and is the result of the molten resin spreading over the two spaces shown by the shaded lines in the figure to form a closed area 227 during injection molding. Although not described one by one, this also applies to the claw recesses of the following other examples.

[0058] By forming the closed area 227 as described above, the cross-sectional area of the gap formed between the outer peripheral surface of the intake pressure sensor 14 and the unit housing 10 at the portion of the claw recess 226b is reduced. Compared with the claw recess 26b of the embodiment, since the inner end of the claw recess 226b forms an angle, it is possible to further reduce the exposed area of the outer peripheral surface of the sensor main body 14a into the claw recess 226b and even the cross-sectional area of the gap, and thus, it is possible to more reliably cut off air bubbles.

[0059] [Another Example 2] As ​As shown, the claw recess 326b of the concave trace 326 in this another example 2 is common with the concave trace 226 in another example 1 in that the inner half region on the inner end side is in a right-angled shape when viewed from above, but is different in that it is formed flat at its inner end. Therefore, as the closed region 327 shrinks, the exposed area of the outer peripheral surface of the sensor body 14a into the claw recess 326b, and even the cross-sectional area of the gap, slightly increases, which is slightly disadvantageous from the perspective of cutting off air bubbles. However, when injection molding, the claw portion abuts against the outer peripheral surface of the sensor body 14a with a certain area, so it is excellent in positioning accuracy.

[0060] [Another example 3] As ​ shown, the claw recess 426b of the concave trace 426 in this another example 3 is common with the concave trace 26 in the embodiment in that its inner end is in an arc shape when viewed from above, but is different in that the curvature radius of the arc is set smaller. Therefore, a closed region 427 corresponding to the shape of the claw recess 426b is formed. Thus, the exposed area of the outer peripheral surface of the sensor body 14a into the claw recess 426b, and even the cross-sectional area of the gap, can be further reduced, so as to more reliably cut off air bubbles.

[0061] [Another example 4] As ​ shown, the claw recess 526b of the concave trace 526 in this another example 4 is circular when viewed from above, and a closed region 527 is formed as a whole around it. This is the result of using a circular claw portion and allowing the molten resin for injection molding to spread to the periphery of the claw portion. The same effects as those of the embodiment can be achieved, and repeated description will not be given.

[0062] The embodiments of the present invention are not limited to the above embodiments. For example, in the above embodiments and another examples 1 to 4, it is embodied as the sensor unit 8 for the throttle device 1 installed in the engine. However, the object of the sensor unit is not limited to the throttle device 1, and it can be embodied as a sensor unit for detecting the working state of various devices.

[0063] In addition, in the above embodiment, the object of positioning is the intake pressure sensor 14, and it is positioned at three positions around its outer peripheral surface by the claw portions 24d of the positioning insert 24. The inner ends of the respective claw portions 24d are in an arc shape, and closed regions 27 for cutting off air bubbles are respectively formed in the claw recesses 26b at the three positions after demolding. In addition, in another examples 1 to 4, claw recesses 226b, 326b, 426b, 526b with different shapes are illustrated, but are not limited thereto. For example, it may be that a sensor having functions and an outer shape other than the intake pressure sensor 14 is used as the object of positioning, or the number of claw recesses 26b, 226b, 326b, 426b, 526b is increased or decreased, or claw recesses with other shapes are provided. Symbol Explanation

[0064] 1 Throttle device 8 Sensor unit 10 Unit housing 14 Intake pressure sensor (sensor) 16 Filling recess 17 Sealing resin filling part 21 Mold 24d Claw part 26b, 226b, 326b, 426b, 526b Claw recess Fb Upper surface during filling.

Claims

1. A sensor unit, comprising: a unit housing which is a synthetic resin unit housing injection-molded with a sensor positioned by a plurality of claw portions provided on a mold as an insert, and includes a plurality of claw recesses and filling recesses. When viewed from above in the demolding direction of each claw portion, the plurality of claw recesses are disposed around the sensor in a posture where their inner ends are in contact with the outer peripheral surface of the sensor, and the filling recesses are formed to open in the demolding direction of the sensor and each claw recess; and a sealing resin filling portion formed in the filling recess by a sealing resin to bury the sensor and each claw recess, wherein the sensor unit is characterized in that each of the claw recesses has a shape in which the width becomes narrower toward the inner end when viewed from above, when viewed from above, closed regions are formed by the synthetic resin forming the unit housing on both sides of the inner end of each claw recess.

2. The sensor unit according to claim 1, wherein each of the claw recesses has a shape that narrows in an arc shape toward the inner end when viewed from above.

3. The sensor unit according to claim 1, wherein each of the claw recesses has a shape that narrows in a tapered shape toward the inner end when viewed from above.

4. The sensor unit according to any one of claims 1 to 3, wherein the sensor is an intake pressure sensor that detects the pressure of intake air supplied to an engine.

5. A throttle device, characterized in that it is installed in an engine and includes the sensor unit according to claim 1.

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