Sensor unit and throttle device having the same

Abstract

To provide a sensor unit in which a sensor is buried in a filling recess of a unit case by a sealing resin, and a defoaming mark can be prevented that occurs on a surface of the sealing resin filling part formed of a cured sealing resin.SOLUTION: A unit case 10 is made of synthetic resin in which a sensor 14 positioned by a plurality of hooks 24d of a mold 21 is formed by an injection molding as an insert part. A sensor unit 8 includes: a plurality of hook recesses 26b provided around a sensor 14 in a state where an inner end thereof being in contact with an outer peripheral face of the sensor 14 in a plan view from a mold release direction of the hook part 24d; a unit case 10 including a filling recess 16 that opens in the mold release direction; and a sealing resin filling part 17 which is formed in the filling recess 16 with sealing resin and in which the sensor 14 and the hook recess parts 26b are buried. Each of the hook parts 26s is tapered in width toward an inner end in plan view, and a sealing region 27 is formed of synthetic resin that forms the unit case 10 on both sides of the inner end.SELECTED DRAWING: Figure 18

Description

[Technical Field]

[0001] The present invention relates to a sensor unit and a throttle device equipped with the same. [Background technology]

[0002] As an example of a sensor unit provided in a conventional throttle device, Patent Document 1 discloses a pressure detection device that detects the intake pressure flowing through the intake passage of a throttle body. A case for the pressure detection device is attached to the throttle body, and a filling recess formed in the case is provided with a pressure introduction passage that communicates with the intake passage, and a circuit board and pressure detection element are disposed within the case. A cover is attached to the filling recess from above, and sealing resin is injected and hardened into the filling recess to embed the circuit board and pressure detection element. This protects the circuit board and pressure detection element, and allows the pressure detection element to detect intake pressure 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 [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, air bubbles may be generated in the sealing resin injected into the filling recess during the sealing resin filling process. This phenomenon becomes more pronounced, for example, when a vacuum is applied to ensure that the sealing resin is distributed throughout the filling recess, or when heating is applied to promote the resin hardening after injection. The generated air bubbles may rise up in the sealing resin and leave defoaming marks on the surface of the sealing resin filling portion formed by the hardened sealing resin. Such defoaming marks are undesirable from the perspective of product aesthetics, and a solution has long been desired.

[0005] The present invention has been made to solve these problems, and its purpose is to provide a sensor unit and a throttle device equipped with the same, which has a structure in which a sensor is embedded in sealing resin within a filling recess formed in a unit case, and which can prevent degassing marks from appearing on the surface of the sealing resin filling portion formed by the sealing resin after hardening, thereby improving the appearance of the product. [Means for solving the problem]

[0006] In order to achieve the above object, the sensor unit of the present invention is a unit case made of synthetic resin that is injection-molded using a sensor positioned by a plurality of claw portions provided in a mold as an insert item, and includes a unit case that includes a plurality of claw recesses that are arranged around the sensor with their inner ends in contact with the outer peripheral surface of the sensor in a plan view from the mold removal direction of each claw portion, and a filling recess that is formed to open in the mold removal direction of the sensor and each claw recess, and a sealing resin filling portion that is formed in the filling recess with sealing resin and that embeds the sensor and each claw recess, and is characterized in that each claw recess has a shape that narrows in width toward its inner end in a plan view, and a sealing area is formed on both sides of the inner end of each claw recess in a plan view from the synthetic resin that forms the unit case.

[0007] In another aspect, each of the claw recesses may have a shape that narrows in an arc shape toward the inner end in plan view.

[0008] In another aspect, each of the claw recesses may have a shape that tapers toward the inner end in plan view.

[0009] In another aspect, the sensor may be an intake pressure sensor that detects the pressure of intake air supplied to the engine.

[0010] In another aspect, the present invention may be a throttle device that is attached to an engine and includes the sensor unit according to claim 1. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a sensor unit and a throttle device equipped with the same, which have a structure in which a sensor is embedded in sealing resin within a filling recess formed in a unit case, and which can prevent degassing marks from appearing on the surface of the sealing resin filling portion formed by the hardened sealing resin, thereby improving the appearance of the product. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a throttle device equipped with a sensor unit according to an embodiment; [Figure 2] FIG. 2 is an exploded perspective view of the throttle device with the sensor unit separated therefrom. [Figure 3] FIG. 10 is a perspective view showing the sensor unit in a position where the upper surface faces upward during ejection. [Figure 4] FIG. 10 is a perspective view showing the sensor unit in a position where the upper surface faces upward during filling. [Figure 5] FIG. 5 is a perspective view corresponding to FIG. 4, in which a sealing resin filling portion is not shown. [Figure 6] 5 is a perspective view corresponding to FIG. 4 in which the sealing resin filling portion is not shown and the circuit board is separated from the sensor unit. [Figure 7] FIG. 7 is a cross-sectional perspective view corresponding to the line VII-VII in FIG. 5. [Figure 8] FIG. 2 is an exploded perspective view showing the configuration of a mold for injection molding the unit case. [Figure 9] 10 is a perspective view showing an upper portion of a positioning nest inserted into a fitting hole. FIG. [Figure 10] FIG. 10 is a plan view showing the relationship between the upper part of the positioning nest inserted into the fitting hole and the sensor body; [Figure 11] FIG. 10 is a perspective view showing an upper portion of the positioning insert when inserted into the fitting hole. [Figure 12] 12 is an enlarged cross-sectional view showing the intake pressure sensor and the positioning insert, taken along line XII-XII in FIG. 10. [Figure 13] FIG. 10 is a perspective view showing the relationship between the lower die and the insert. [Figure 14] FIG. 10 is a perspective view showing a state in which an insert is placed on a lower die. [Figure 15] FIG. 10 is a perspective view showing a state in which a connector nest is placed on a lower die. [Figure 16] FIG. [Figure 17] FIG. 7 is an enlarged plan view of a concave mark corresponding to part A in FIG. 6. [Figure 18] FIG. 8 is an enlarged perspective cross-sectional view of a concave mark corresponding to part B in FIG. 7. [Figure 19] FIG. 11 is a plan view corresponding to FIG. 10 and showing a comparative example of the prior art. [Figure 20] FIG. 12 is a perspective view corresponding to FIG. 11 and showing the comparative example. [Figure 21] FIG. 18 is an enlarged plan view corresponding to FIG. 17 and showing the comparative example. [Figure 22] FIG. 19 is an enlarged cross-sectional perspective view corresponding to FIG. 18 and showing the comparative example. [Figure 23] FIG. 18 is an enlarged plan view showing Modified Example 1 and corresponding to FIG. [Figure 24] FIG. 18 is an enlarged plan view showing a second modification corresponding to FIG. 17. [Figure 25] FIG. 18 is an enlarged plan view showing a third modification corresponding to FIG. 17. [Figure 26] FIG. 18 is an enlarged plan view showing a fourth modification corresponding to FIG. 17. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sensor unit according to an embodiment of the present invention and a throttle device including the same will now be described. <Overall configuration of the throttle device> FIG. 1 is a perspective view showing a throttle device equipped with a sensor unit of this embodiment, and FIG. 2 is an exploded perspective view of the throttle device with the sensor unit separated therefrom.

[0014] The throttle device 1 of this embodiment is mounted on a single-cylinder engine mounted on a motorized bicycle, and a single throttle bore 2a is formed through the throttle body 2. When mounted on the engine, the throttle bore 2a communicates with the inside of the engine cylinder, and intake air from an air cleaner (not shown) flows through the throttle bore 2a and is supplied to the inside of the cylinder.

[0015] A throttle valve 3 is supported within the throttle bore 2a by a throttle shaft 4 so that it can be opened and closed, and the left end of the throttle shaft 4 in Figures 1 and 2 protrudes outward from the throttle body and has a wire drum 5 attached to it, with a return spring 6 biasing the throttle valve 3 in the closing direction. Although not shown, the vehicle's throttle grip is connected to the wire drum 5 via a throttle wire, and in conjunction with the operation of the throttle grip, the throttle shaft 4 rotates together with the wire drum 5 to open and close the throttle valve 3, thereby adjusting the amount of air intake into the engine.

[0016] A sensor unit 8 is attached to the right side of the throttle body 2 with a screw 7, and this sensor unit 8 detects the opening of the throttle valve 3, the temperature of the intake air flowing through the throttle bore 2a, and the pressure of the intake air. A harness from an ECU (engine control unit) installed in the vehicle is connected to a connector 8a provided on the sensor unit 8. Detection signals related to the throttle opening, intake air temperature, and intake air pressure are output from the sensor unit 8 and input to the ECU, which controls the operating state of the engine based on these signals. The 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, which controls the idle speed. The sensor unit 8 will be described in detail below.

[0017] <Configuration of sensor unit 8> Fig. 3 is a perspective view showing the sensor unit 8, and Fig. 4 is a perspective view showing the sensor unit 8 upside down from Fig. 3. As will be described in detail later, the sensor unit 8 is manufactured in the following order: injection molding of the unit case 10, and molding of the sealing resin layer by filling with sealing resin. 3 shows the unit case 10 in a position where the surface that is attached to the throttle body 2 faces upward, and the unit case 10 is injection molded in this position, and the upper surface of the unit case 10 at this time will be referred to as the injection upper surface Fa. Also, in FIG. 4, the unit case 10 is shown in a position where the opposite surface of the unit case 10 faces upward, and the sealing resin is filled in this position, and the upper surface of the unit case 10 at this time will be referred to as the filling upper surface Fb.

[0018] As shown in Figure 3, the unit case 10 is manufactured by injection molding a synthetic resin material, and an annular fitting portion 10a is integrally formed on the upper surface Fa at the time of injection. The unit case 10 is attached with screws 7 in a state where the annular fitting portion 10a is fitted into a fitting hole (not shown) on the throttle body 2 side and positioned. Note that reference numeral 11 denotes a metal collar through which the screw 7 is inserted, and each is inserted into the unit case 10.

[0019] A cylindrical portion 12a of the throttle opening sensor 12 is inserted into the annular fitting portion 10a, and as will be described later, three terminals 12b of a magnetic field change detection portion 12c (shown in FIG. 6) disposed inside the cylindrical portion 12a face downward in FIG. 3, in other words, face 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, and when the sensor unit 8 is attached to the throttle body 2, the cylindrical portion 12a, the magnetic field change detection portion 12c, and the magnetic field generation portion constitute a magnetic throttle opening sensor 12. Therefore, when the magnetic field generation portion rotates together with the throttle shaft 4, a signal corresponding to the rotation angle is output from the throttle opening sensor 12.

[0020] Furthermore, a detector 10b is integrally formed on the upper surface Fa of the unit case 10 at the time of injection and extends upward in FIG. 3. As indicated by the dashed line in the figure, a sensor body 13a of the intake air temperature sensor 13 is disposed at the tip of the detector 10b, and two terminals 13b extend downward in FIG. 3 from the sensor body 13. The intake air temperature sensor 13 is then completed by filling the detector 10b with sealing resin. When the sensor unit 8 is attached to the throttle body 2, the tip of the detector 10b protrudes upstream of the throttle valve 3 in the throttle bore 2a. Therefore, the sensor body 13a is exposed to the intake air flowing through the throttle bore 2a, and a signal corresponding to the intake air temperature is output.

[0021] Furthermore, a pressure chamber 10c is recessed into the upper surface Fa of the unit case 10 at the time of injection, and a pressure case 14c having a detection hole 14d in the center is exposed within the pressure chamber 10c. As will be described later, a sensor main body 14a is placed on and connected to the underside of the pressure case 14c inserted into the unit case 10. Three terminals 14b extend downward in FIG. 3 from the sensor main body 14a, thereby constituting the intake pressure sensor 14.

[0022] With the sensor unit 8 attached to the throttle body 2, the pressure chamber 10c communicates with the throttle bore 2a downstream of the throttle valve 3 through a pressure passage (not shown) formed in the throttle body 2. Therefore, the pressure of the intake air flowing through the throttle bore 2a acts on the sensor main body 14a through the pressure passage, pressure chamber 10c, detection hole 14d, and the inside of the pressure case 14c, causing the sensor main body 14a to output a signal corresponding to the intake air pressure.

[0023] 5 is a perspective view corresponding to FIG. 4, but without showing the sealing resin filled portion; FIG. 6 is a perspective view corresponding to FIG. 4, but without showing the sealing resin filled portion, but with the circuit board separated from the sensor unit 8; and FIG. 7 is a cross-sectional perspective view corresponding to line VII-VII in FIG. 5.

[0024] 4, a ring-shaped filling recess 16 is formed on the upper surface Fb of the unit case 10 when filled, surrounding most of the area, so as to open in the die-removal direction described below, and a sealing resin filling portion 17 is formed inside the filling recess 16 and filled. The sealing resin filling portion 17 is formed by injecting and hardening a sealing resin into the filling recess 16 by sealing resin filling, and the sealing resin used is, for example, a thermosetting synthetic resin material such as epoxy resin, or a photocurable synthetic resin material.

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

[0026] Such circuit board 18 and each terminal 12b, 13b, 14b, 19 are embedded in a sealing resin filling portion 17 for protection, and the surface of sealing resin filling portion 17 forms the upper surface Fb of sensor unit 8 when filled. For this reason, the condition of the surface of sealing resin filling portion 17 affects the aesthetic appearance of sensor unit 8, and ultimately the aesthetic appearance of throttle device 1.

[0027] As will be described in detail later, during injection molding of the unit case 10, the intake pressure sensor 14 is positioned by the claws 24d of the mold 21, and a minute gap may be formed between the outer circumferential surface of the intake pressure sensor 14 and the unit case 10 at the location of the concave mark 26 created by the removal of the claws 24d. During the subsequent sealing resin filling, air bubbles remaining on the outer circumferential surface of the sensor body 14a of the intake pressure sensor 14 may pass through the gap and become mixed into the sealing resin injected into the filling recess 16. Such air bubbles rise up in the sealing resin and, as shown in FIG. 4, remain as defoaming marks P on the surface of the sealing resin filling portion 17 formed by the hardened sealing resin, thereby affecting the aesthetic appearance of the sensor unit 8.

[0028] In view of such a problem, in this embodiment, a countermeasure is taken for the claw portion 24d that positions the intake pressure sensor 14. Therefore, the procedure for injection molding the unit case 10 will be described below, focusing on the positioning of the intake pressure sensor 14.

[0029] <Injection molding procedure for unit case 10> Figure 8 is an exploded oblique view showing the configuration of a mold for injection molding the unit case 10, Figure 9 is an oblique view showing the upper part of the positioning nest inserted and placed in the fitting hole, Figure 10 is a plan view showing the relationship between the upper part of the positioning nest inserted and placed in the fitting hole and the sensor main body 14a, Figure 11 is an oblique view showing the upper part of the positioning nest when inserted and placed in the fitting hole, Figure 12 is an enlarged cross-sectional view corresponding to line XII-XII in Figure 10 showing the intake pressure sensor 14 and the positioning nest, Figure 13 is an oblique view showing the relationship between the lower mold and the insert item, Figure 14 is an oblique view showing the state where the insert item is placed on the lower mold, Figure 15 is an oblique view showing the state where the connector nest is placed on the lower mold, and Figure 16 is an oblique view showing the state where the molds are clamped.

[0030] As shown in FIG. 8, the mold 21 includes a lower mold 22 and an upper mold 23, which correspond to the mother mold, and a positioning insert 24 and a connector molding insert 25, which function as inserts. The upper surface of the lower mold 22 has a shape corresponding to the upper surface Fb of the unit case 10 during filling, and the lower surface of the upper mold (not shown) has a shape corresponding to the upper surface Fa during injection, forming a cavity between them in the mold clamped state shown in FIG. 16. Therefore, when molten resin is injected into the cavity, the unit case 10 is molded in the orientation shown in FIG. 3, with the upper surface Fa facing upward during injection. Note that this orientation of the unit case 10 during molding is determined so that each insert is positioned and placed on the lower mold 22 with the terminals 12b, 13b, 14b, and 19 facing downward.

[0031] The injection molding procedure will be described in detail below, including the configuration of the mold 21. 10 and 11, the sensor body 14a of the intake air pressure sensor 14, which is an insert part, is shown by a two-dot chain line, and a fitting hole 22a is formed in the lower mold 22 in the vertical direction directly below the position where the sensor body 14a is inserted. A positioning nest 24 can be inserted into the fitting hole 22a from below, and when inserted and arranged, the upper end of the positioning nest 24 protrudes from the upper surface of the lower mold 22 into the cavity, making it possible to position the intake air pressure sensor 14.

[0032] As shown in Fig. 12, intake pressure sensor 14 is formed by connecting sensor main body 14a and pressure case 14c, with each case overlapping the other. In the plan view of Fig. 10, the underside of sensor main body 14a is a plane formed by cutting out a portion of a circle in a straight line, and the three terminals 14b bend from the straight line and extend downward. When intake pressure sensor 14 is placed on lower mold 22, each terminal 14b is inserted into a terminal hole 22b formed in lower mold 22.

[0033] As shown in Fig. 9, the upper end surface 24a of the positioning nest 24 also forms a flat surface corresponding to the shape of the lower surface of the sensor main body 14a, and three approximately equal portions of the outer periphery are expanded outward in a rectangular shape. Positioning claws 24d protrude upward from each of the expanded portions 24b formed by this, via tapered surfaces 24c facing in three directions. The inner ends of each claw 24d, specifically the ends facing the center of the sensor main body 14a in the plan view shown in Fig. 10, abut against the outer periphery of the sensor main body 14a. The insertion of the terminals 14b into the terminal holes 22b restricts the rotation of the sensor main body 14a, thereby positioning the sensor main body 14a in the plan view. In addition, the sensor body 14a is positioned in the vertical direction by the lower surface of the sensor body 14a abutting against the upper end surface 24a of the positioning nest 24, and as a result, the sensor body 14a and the pressure case 14c connected to the sensor body 14a are held in a predetermined position within the cavity of the mold 21.

[0034] As shown in FIG. 12, the corner 14e between the lower surface and the outer peripheral surface of the sensor main body 14a is rounded, so the actual contact area in the vertical direction between the inner end of the claw portion 24d and the outer peripheral surface of the sensor main body 14a is dimension L.

[0035] As shown in Fig. 13, the insert parts other than the intake pressure sensor 14 include the cylindrical portion 12a of the throttle opening sensor 12, the connector terminal 19, and the collar 11. These insert parts are not directly related to the gist of the present invention and will only be briefly described, but as shown in Fig. 14, they are each placed in a predetermined position on the lower mold 22. Next, as shown in Fig. 15, a connector molding insert 25 is placed on the lower mold 22, and after the mold is clamped as shown in Fig. 16, molten resin is injected into the cavity, completing the molding of the unit case 10 in the position shown in Fig. 3.

[0036] When the unit case 10 is turned over, the filling top surface Fb faces upward, as shown in Figures 6 and 7. On the filling top surface Fb, the terminals 14b of the intake pressure sensor 14 and the base ends of the connector terminals 19 protrude upward, and the cylindrical portion 12a of the throttle position sensor 12 and the detector 10b of the intake air temperature sensor 13 open upward. The sensor body 14a of the intake pressure sensor 14 is exposed, and three recesses 26 are formed around the sensor body 14a as a result of the punching out of the claws 24d of the positioning insert 24. The recesses 26 are shaped like the tapered surfaces 24c and claws 24d of the positioning insert 24, and are disposed so as to surround the sensor body 14a with their inner ends in contact with the outer circumferential surface of the sensor body 14a.

[0037] These portions are surrounded by a filling recess 16 which opens upward. Then, in the next step, sealing resin filling is carried out to fill these portions with a sealing resin filling portion 17.

[0038] <Procedure for filling sealing resin> First, prior to filling with sealing resin, as shown in Figures 5 and 6, the terminals 13b of the intake air temperature sensor 13 and the terminals 12b of the throttle position sensor 12 are inserted and soldered into the through holes 18a of the circuit board 18, with the sensor body 13a supported at the lower end of the downwardly extending terminals 13b and the magnetic field change detection unit 12c supported at the lower end of the downwardly extending terminals 12b. When the circuit board 18 is then placed in a predetermined position on the unit case 10, the sensor body 13a and terminals 13b of the intake air temperature sensor 13 are inserted into the detector 10b, and the magnetic field change detection unit 12c of the throttle position sensor 12 is disposed within the cylindrical portion 12a. At the same time, the terminals 14b of the intake air pressure sensor 14 and the base end of the connector terminal 19 protrude upward through the through holes 18a, 18b of the circuit board 18.

[0039] The protruding terminals 14b, 19 are inserted and soldered into the through holes 18a, 18b of the circuit board 18, respectively, and then sealing resin is poured into the filling recess 16. The sealing resin penetrates into the detector 10b and fills the filling recess 16 while soaking in the circuit board 18, the terminals 12b, 14b, 19, and the recessed marks 26 around the sensor body 14a. After hardening, a sealing resin filling portion 17 is formed, and the circuit board 18 and the terminals 12b, 13b, 14b, 19, etc. are embedded therein, thereby completing the production of the sensor unit 8.

[0040] <Behavior of air bubbles when filling with sealing resin> After injection molding, air bubbles may remain between the unit case 10, specifically the resin forming the unit case 10, and the cylindrical portion 12a of the throttle opening sensor 12 or the intake pressure sensor 14 inserted therein, due to various factors. For example, air may accumulate inside the hollow intake pressure sensor 14, and some of this air may leak to the outside through the gap between the sensor main body 14a and the pressure case 14c during injection molding, remaining as air bubbles on the outer surface of the sensor main body 14a. Even if such air bubbles remain, the tight contact between the surfaces of the sensors 12, 14 and the unit case 10 makes it difficult for the air bubbles to pass through, so there is little chance that the air bubbles will be mixed into the sealing resin injected into the filling recess 16 during the sealing resin filling process.

[0041] However, during injection molding, the intake pressure sensor 14 is positioned by the claws 24d, and as explained with reference to Figures 6 and 7, recessed marks 26 are formed in three places around the periphery of the sensor main body 14a when the claws 24d are removed from the mold. Therefore, the outer peripheral surface of the sensor main body 14a is exposed at the locations of the recessed marks 26, which makes it easier for air bubbles from below to pass through the recessed marks 26 and move upward, potentially becoming mixed into the sealing resin.

[0042] <Details of the recessed mark 26 that blocks air bubbles> Fig. 17 is an enlarged plan view of the concave mark 26 corresponding to part A in Fig. 6, and Fig. 18 is an enlarged perspective cross-sectional view of the concave mark 26 corresponding to part B in Fig. 7, with the other two concave marks 26 having the same shape. Below, measures to prevent air bubbles from passing through the concave marks 26 will be explained based on these figures and Figs. 10 and 11 which show the claw portions 24d during injection molding.

[0043] In simple terms, the countermeasure of this embodiment 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 form the sealing area 27 described below by spreading the molten resin during injection molding over the reduced area, and this sealing area 27 reduces the cross-sectional area of the gap through which air bubbles can slip from bottom to top, thereby blocking the air bubbles.

[0044] 10 and 11, the inner half of each claw 24d narrows in a circular arc in plan view, resulting in a single point of the inner end contacting the outer circumferential surface of the sensor body 14a. As shown in Fig. 12, the outer circumferential surface of the sensor body 14a has a draft angle that tapers slightly downward, and the inner ends of each claw 24d also have a slight taper, but they have substantially the same cross-sectional shape in any vertical direction and contact each other at a single point. As a result, the inner ends of the claws 24d and the outer circumferential surface of the sensor body 14a are in line contact.

[0045] With this interrelationship in mind, molten resin is injected into the cavity of the mold 21 to form the unit case 10, and when each of the claws 24d is removed, a concave mark 26 having the shape shown in Figures 17 and 18 is formed around the sensor main body 14a. That is, as shown in Figure 9, on each expansion portion 24b of the positioning insert 24, the claws 24d protrude upward via tapered surfaces 24c facing three directions. Therefore, as shown in Figures 17 and 18, in a plan view of each of the claws 24d seen from the removal direction, the concave mark 26 has a tapered recess 26a having a shape transferred from the tapered surfaces 24c on three sides, and a claw recess 26b having a shape transferred from the claw 24d, further recessed at approximately the center.

[0046] 17 and 18. Because the inner ends of the claw portions 24d are arc-shaped in plan view, two spaces are formed between the claw portions 24d and the outer peripheral surface of the sensor main body 14a, as shown by hatching in Figures 17 and 18. During injection molding, the molten resin fills each space and hardens, forming the claw recessed portions 26b with arc-shaped inner ends. Hereinafter, these spaces filled with the molten resin will be referred to as sealing regions 27. By forming sealing region 27, a narrow region at a point on the outer peripheral surface of the sensor main body 14a where the inner ends of the claw portions 24d abut is locally exposed within the claw recessed portions 26b, but most of the regions on both sides are covered by sealing region 27.

[0047] 12, the molten resin also spreads and hardens at rounded corners 14e of sensor main body 14a, so the vertical length of sealing area 27 is essentially the dimension L in Fig. 18. Directly below claw recess 26b, the outer peripheral surface of sensor main body 14a and unit case 10 come into contact as shown by the two-dot chain line in Fig. 17, and when sealing resin is filled, there is room for air bubbles to pass upward from below between the two, but these air bubbles are blocked by sealing area 27 located directly above.

[0048] Just to be clear, the important point of this embodiment is that during injection molding, two spaces are intentionally formed between the inner end of the claw portion 24d and the outer peripheral surface of the sensor main body 14a, and molten resin is spread through each space to form a sealing region 27, which blocks air bubbles that could cause defoaming marks P when the sealing resin is subsequently filled. When embedding a component such as a sensor in a case using conventional sealing resin filling, a space is sometimes intentionally formed between the inner wall of the case and the component to ensure that the injected sealing resin is distributed throughout the case. However, the intentionally formed space in the known technology is intended to improve the flow of the sealing resin during filling, whereas the intentionally formed space in the present embodiment is intended to form a sealing region 27 with molten resin during injection molding, which clearly differs in purpose and the molding process to which it is applied. Furthermore, while the sealing resin hardened within the space in the known technology does not perform any particular function, the sealing region 27 formed with molten resin in the present embodiment performs the important function of blocking air bubbles during the subsequent sealing resin filling process, which also clearly differs in this respect.

[0049] Comparison of this embodiment with the prior art In contrast to the shape of the claw portion 24d of this embodiment as described above, a claw portion 124d having the shape shown in Figures 19 and 20 is generally considered, and a concave mark 126 having the shape shown in Figure 21 is formed in the unit case 10 after being demolded. Below, these claw portions 124d and concave marks 126 will be considered as prior art and will be compared with those of this embodiment.

[0050] 19 is a plan view corresponding to FIG. 10 showing a comparative example of the prior art, FIG. 20 is a perspective view corresponding to FIG. 11 showing the same comparative example, FIG. 21 is an enlarged plan view corresponding to FIG. 17 showing the same comparative example, and FIG. 22 is an enlarged cross-sectional perspective view corresponding to FIG. 18 showing the same comparative example. In consideration of the function of the claws to position the sensor main body 14a, the general idea is that each claw 124d is formed to have a square shape in a plan view, and the flat surfaces corresponding to its inner ends are configured to abut against the outer peripheral surface of the sensor main body 14a, as shown in Figures 19 and 20. The shape of the tapered surfaces 24c facing in three directions is the same as in the embodiment.

[0051] For this reason, when sensor main body 14a is positioned, the outer peripheral surface of sensor main body 14a and the inner ends of claw portions 124d are in a relationship that is close to surface contact, and only a minute gap is formed between the two, specifically a gap so minute that there is no room for molten resin with a certain degree of viscosity to get in. For this reason, the molten resin does not fill the gap during injection molding, and after demolding, claw recesses 126b without sealing regions 27 shown in Figures 21 and 22 are formed, and most of the area of the outer peripheral surface of sensor main body 14a that was in contact with the inner ends of claw portions 124d is exposed within claw recesses 126b.

[0052] Then, when the sealing resin is filled, in the comparative example, as shown by the dashed arrow in Figure 22, air bubbles remaining on the outer peripheral surface of the sensor main body 14a during injection molding rise up and reach the claw recess 126b. There is no sealing region 27 in the claw recess 126b, 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 slip through the gaps and mix into the sealing resin, and then rise up in the sealing resin. As a result, the air bubbles remain on the surface of the sealing resin filling portion 17 after hardening as defoaming marks P, which detracts from the aesthetic appearance of the sensor unit 8.

[0053] When filling the sealing resin, vacuuming may be performed to ensure that the sealing resin is thoroughly distributed within the filling recess 16, or heating may be performed to promote the resin hardening after injection. Under these conditions, air bubbles are particularly likely to be generated. In addition, if resin materials with different linear expansion coefficients are used for the unit case 10 and the sensor main body 14a, air bubbles are likely to slip through as the gap widens due to heating. The comparative example is easily affected by these conditions, and when all of these conditions are met, the generation of defoaming marks P becomes noticeable.

[0054] In contrast, in this embodiment, as shown by the dashed arrow in Figure 18, most of the air bubbles that reach the claw recess 26b are blocked by the sealing region 27, preventing them from entering the sealing resin in the filling recess 16. Because a narrow area of the outer surface of the sensor body 14a where the inner end of the claw recess 26b abuts is exposed within the claw recess 26b, air bubbles may pass through. However, because the cross-sectional area of the gap is smaller than that of the comparative example, only a very small amount of air bubbles pass through. Furthermore, even if the above-mentioned sealing resin filling conditions that tend to generate air bubbles or the resin material conditions regarding the linear expansion coefficient are met, the small cross-sectional area of the gap prevents air bubbles from passing through. Therefore, defoaming marks P on the surface of the sealing resin filling portion 17 can be prevented, and the aesthetic appearance of the sensor unit 8 is not impaired.

[0055] As a result, according to this embodiment, the intake pressure sensor 14 is positioned within the filling recess 16 formed in the unit case 10 and is embedded in the sealing resin, and the appearance of the product can be improved by preventing degassing marks P from appearing on the surface of the sealing resin filling portion 17 formed by the hardened sealing resin.

[0056] As described above, the gist of the present invention is to reduce the contact area between the inner ends of the claw portions 24d and the outer peripheral surface of the sensor main body 14a, allowing the molten resin to fill the reduced space during injection molding to form a sealing region 27, thereby blocking air bubbles. Therefore, the claw recesses 26b of the concave marks 26 must be shaped so that their widths narrow toward their inner ends in a plan view. In other words, as shown in FIG. 17, the desired function can be achieved if the width dimension Lin of the inner ends of the claw recesses 26b in the circumferential direction of the sensor main body 14a is set to be less than the maximum width dimension Lout of any other portion, including the outer peripheral end. Below, we will explain Alternative Examples 1 to 4 as modifications that satisfy this condition.

[0057] [Example 1] As shown in FIG. 23 , the claw recess 226b of the concave mark 226 of this modified example 1 has a shape that tapers toward the inner end in a plan view. Specifically, the inner half of the claw recess 226b forms a right angle in a plan view, and the inner end forms an angle and makes line contact with the outer circumferential surface of the sensor main body 14a, forming a substantially uniform cross-sectional shape in the vertical direction. Although not shown, the shape of this claw recess 226b was formed using a claw portion of a corresponding shape, resulting from the molten resin permeating into the two spaces indicated by hatching in the figure during injection molding to form a sealing region 227. Although not described in detail, this point is similar to the claw recesses of the following modified examples.

[0058] The formation of sealing region 227 as described above reduces the cross-sectional area of the gap formed between the outer peripheral surface of intake pressure sensor 14 and unit case 10 at claw recess 226b. Compared to claw recess 226b of the embodiment, the inner end of claw recess 226b is angled, which further reduces the exposed area of the outer peripheral surface of sensor main body 14a in claw recess 226b, and therefore the cross-sectional area of the gap, thereby more reliably blocking air bubbles.

[0059] [Example 2] 24, the claw recess 326b of the concave mark 326 of Alternative Example 2 is different from the concave mark 226 of Alternative Example 1 in that half of the inner end is perpendicular in plan view, but the inner end is flat. Therefore, as the sealing area 327 is reduced, the exposed area of the outer circumferential surface of the sensor main body 14a in the claw recess 326b, and therefore the cross-sectional area of the gap, increases slightly, which is somewhat disadvantageous from the perspective of blocking air bubbles. However, during injection molding, the claw portion abuts the outer circumferential surface of the sensor main body 14a over a certain area, which provides excellent positioning accuracy.

[0060] [Example 3] 25, the claw recess 426b of the concave mark 426 of this modified example 3 is similar to the concave mark 26 of the embodiment in that its inner end is arc-shaped in plan view, but differs in that the radius of curvature of the arc is set smaller. Therefore, since a sealing region 427 is formed in a shape corresponding to such claw recess 426b, the exposed area of the outer circumferential surface of sensor main body 14a in claw recess 426b, and therefore the cross-sectional area of the gap, can be further reduced, making it possible to more reliably block air bubbles.

[0061] [Example 4] 26, the claw recess 526b of the concave mark 526 of this modification 4 is circular in plan view, and a sealing region 527 is formed around the entire periphery. This is the result of using a circular claw portion to allow the molten resin from the injection molding to spread around the claw portion. Although a redundant description will not be given, the same effects as those of the embodiment can be achieved.

[0062] The aspects of the present invention are not limited to this embodiment. For example, in the above embodiment and modified examples 1 to 4, the sensor unit 8 is embodied as a sensor unit for a throttle device 1 attached to an engine. However, the sensor unit is not limited to the throttle device 1, and can be embodied as a sensor unit that detects the operating state of various devices.

[0063] In the above embodiment, the target of positioning is intake pressure sensor 14, and three locations around the outer periphery of the sensor are positioned by claws 24d of positioning nest 24. The inner ends of each claw 24d are arc-shaped, and sealing regions 27 for blocking air bubbles are formed in each of the three claw recesses 26b after die-cutting. While different shapes of claw recesses 226b, 326b, 426b, and 526b are illustrated in Alternative Examples 1 to 4, the present invention is not limited to these. For example, a sensor having a function or shape other than intake pressure sensor 14 may be positioned, or the number of claw recesses 26b, 226b, 326b, 426b, and 526b may be increased or decreased, or the claw recesses may have a different shape. [Explanation of symbols]

[0064] 1 Throttle device 8 Sensor Unit 10 unit case 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 Top surface when filling

Claims

1. A unit case made of synthetic resin that is injection molded with a sensor inserted into it, the sensor being positioned by a plurality of claws provided in a mold, a plurality of claw recesses arranged around the sensor with their inner ends in contact with the outer peripheral surface of the sensor in a plan view seen from the mold-removal direction of each of the claw portions; a unit case including the sensor and a filling recess formed to open in the mold-removing direction of each of the claw recesses; a sealing resin filling portion formed in the filling recess by a sealing resin, the sealing resin filling portion burying the sensor and each of the claw recesses; In a sensor unit comprising: Each of the claw recesses has a shape that narrows toward its inner end in the plan view, In the plan view, sealing regions are formed on both sides of the inner ends of the claw recesses by the synthetic resin that forms the unit case. A sensor unit characterized by:

2. Each of the claw recesses has a shape that narrows in an arc shape toward the inner end in a plan view.

2. The sensor unit according to claim 1.

3. Each of the claw recesses has a shape that tapers toward the inner end in plan view.

2. The sensor unit according to claim 1.

4. The sensor is an intake pressure sensor that detects the pressure of intake air supplied to the engine.

4. The sensor unit according to claim 1, wherein the sensor unit is a sensor unit having a first electrode and a second electrode.

5. A vehicle equipped with the sensor unit according to claim 1, A throttle device characterized by:

Images