JP7589474B2 - Resin molded product and method for manufacturing the same - Google Patents

Description

The present invention relates to a resin molded product and a method for manufacturing a resin molded product.

Conventionally, there are composite parts in which an insert, which is an insert for a metal part, etc., is integrated with synthetic resin. Such composite parts are manufactured, for example, by insert molding. Insert molding is a molding technique in which an insert is attached to an open mold, and then the mold is closed and injection molding is performed. Inside the mold, the insert is enveloped in molten resin that is injected into the mold. The composite part is obtained when this molten resin cools and solidifies.

For example, Patent Document 1 discloses a sensor device that detects the torque and rotation angle of a shaft. An arc-shaped metal member (magnetic collecting member) is insert-molded into the housing of this sensor device. A portion of this metal member is exposed to the internal space of the housing. In order to expose the metal member, it is preferable to bring the metal member into contact with the mold (such as a nest) without any gaps during insert molding.

JP 2019-74365 A

However, when insert molding conventional resin molded products, including the sensor device of Patent Document 1, gaps can occur between the insert and the mold due to dimensional tolerances, etc. In this case, there is a risk of burrs being generated when molten resin flows into the gap between the insert and the mold.

The object of the present invention is to provide a resin molded product and a method for manufacturing the resin molded product that can suppress the generation of burrs caused by the overflow of molten resin during insert molding.

The resin molded product that can achieve the above object is a resin molded product having an internal space formed by insert molding an insert. The insert has a first insert portion and a second insert portion provided so as to protrude from the outer surface of the first insert portion. The second insert portion has a first surface having a portion exposed to the space without being covered by resin, a second surface that is a surface opposite to the first surface and is located downstream of the flow direction of the molten resin injected during insert molding with respect to the first surface and is covered by resin, and a third surface that connects the first surface and the second surface and is covered by resin. At least a part of a corner portion between the second surface and the third surface is provided with a fourth surface configured to guide the molten resin flowing from the first surface side from the first surface side to the second surface side.

In the following description, for convenience of explanation, the portion of the first surface that is exposed to the internal space of the resin molded product may be simply referred to as the first surface.
In order to expose the first surface of the second insert part to the space inside the resin molded product, it is preferable to contact the first surface and the mold without any gap during insert molding. This is because if there is a gap between the first surface and the mold, molten resin may flow into the gap between the first surface and the mold, causing burrs. In this regard, according to the above configuration, during insert molding, the molten resin flowing in from the first surface side of the second insert part is guided to the second surface side by the fourth surface. At this time, the pressure of the molten resin flowing into the second surface side acts on the second insert part in a direction from the second surface to the first surface. Therefore, the second insert part is pressed against the mold by the pressure of the molten resin flowing into the second surface side. As a result, the gap between the first surface and the mold is further reduced, so that the molten resin is prevented from flowing into the gap between the first surface and the mold. Therefore, it is possible to suppress the generation of burrs due to the overflow of the molten resin during insert molding.

In the above-mentioned resin molded product, the fourth surface may include two inclined surfaces located on opposite sides of each other in a direction perpendicular to the protruding direction of the second insert portion relative to the outer surface of the first insert portion, and these inclined surfaces may be inclined so as to approach each other from the first surface side toward the second surface side.

With this configuration, the molten resin flowing in from the first surface side of the second insert part is guided to the second surface side by the two inclined surfaces. This makes it easier for the molten resin to flow from the first surface side to the second surface side.

In the above-mentioned resin molded product, the second insert portion may be rectangular plate-shaped, and the two inclined surfaces may be provided over the entire length of the second insert portion in the direction of protrusion relative to the outer surface of the first insert portion.

With this configuration, the molten resin flowing in from the first surface side of the second insert part is guided more efficiently to the second surface side by the two inclined surfaces. This makes it even easier for the molten resin to flow from the first surface side to the second surface side.

In the above-described resin molded product, a connector fitting portion into which a connector is fitted may be provided in the vicinity of the second insert portion.
When a connector fitting portion is provided near the second insert portion, it may be necessary to provide a space on the contact surface side of the mold with the second insert portion to avoid interference with the connector fitting portion. In this case, it becomes more necessary to prevent the molten resin from flowing into the space inside the mold through the gap between the second insert portion and the mold. For this reason, as in the above configuration, it is preferable to adopt a configuration of the insert having a fourth surface that guides the molten resin from the first surface side of the second insert portion to the second surface side.

A method for manufacturing a resin molded product that can achieve the above object is a method for manufacturing a resin molded product having a space inside, and includes a step of setting an insert inside a mold and a step of injecting molten resin into a cavity formed inside the mold. The insert includes a first insert portion and a second insert portion provided to protrude from the outer surface of the first insert portion. The second insert portion includes a first surface having a portion that is maintained in contact with the mold, a second surface that is a surface opposite to the first surface and is located downstream of the flow direction of the molten resin with respect to the first surface and is maintained in a state in which a gap is formed between the second surface and the mold, and a third surface that connects the first surface and the second surface and is maintained in a state in which a gap is formed between the second surface and the mold. At least a part of a corner portion between the second surface and the third surface is provided with a fourth surface that guides the molten resin flowing from the first surface side from the first surface side to the second surface side.

In the following explanation, for the sake of convenience, the portion of the first surface that is maintained in contact with the mold, or the portion of the first surface that is exposed to the internal space of the resin molded product, may be simply referred to as the first surface.

According to this manufacturing method, the first surface is exposed to the internal space of the resin molded product without being covered with resin. The second surface, which is the surface opposite the first surface of the second insert part, and the third surface, which is the surface connecting the first surface and the second surface, are each covered with resin. This results in a resin molded product in which the first surface of the second insert part is exposed to the internal space of the resin molded product.

Here, in order to expose the first surface of the second insert part to the space inside the resin molded product, it is preferable to make the first surface and the mold contact each other without any gaps during insert molding. This is because if there is a gap between the first surface and the mold, molten resin may flow into the gap between the first surface and the mold, causing burrs. In this regard, according to the above manufacturing method, during insert molding, the molten resin flowing in from the first surface side of the second insert part is guided to the second surface side by the fourth surface. At this time, the pressure of the molten resin flowing into the second surface side acts on the second insert part in a direction from the second surface to the first surface. Therefore, the second insert part is pressed against the mold by the pressure of the molten resin flowing into the second surface side. As a result, the gap between the first surface and the mold is further reduced, and the molten resin is prevented from flowing into the gap between the first surface and the mold. Therefore, it is possible to suppress the generation of burrs due to the overflow of molten resin during insert molding.

In the above-mentioned method for manufacturing a resin molded product, the fourth surface may include two inclined surfaces located on opposite sides of each other in a direction perpendicular to the protruding direction of the second insert portion relative to the outer surface of the first insert portion, and these inclined surfaces may be inclined so as to approach each other from the first surface side toward the second surface side.

According to this manufacturing method, the molten resin flowing in from the first surface side of the second insert part is guided to the second surface side by the two inclined surfaces. This makes it easier for the molten resin to flow from the first surface side to the second surface side.

In the above-mentioned method for manufacturing a resin molded product, the second insert portion may be rectangular plate-shaped, and the two inclined surfaces may be provided over the entire length of the second insert portion in the direction of protrusion relative to the outer surface of the first insert portion.

According to this manufacturing method, the molten resin flowing in from the first surface side of the second insert part is guided more efficiently to the second surface side by the two inclined surfaces. This makes it even easier for the molten resin to flow from the first surface side to the second surface side.

In the above-described method for manufacturing a resin molded product, a connector fitting portion into which a connector is fitted may be provided near the second insert portion.
When a connector fitting portion is provided near the second insert portion, it may be necessary to provide a space on the contact surface side of the mold with the second insert portion to avoid interference with the connector fitting portion. In this case, it becomes more necessary to prevent the molten resin from flowing into the space inside the mold through the gap between the second insert portion and the mold. For this reason, as in the above manufacturing method, it is preferable to adopt a configuration of the insert having a fourth surface that guides the molten resin from the first surface side of the second insert portion to the second surface side.

The resin molded product and the method for manufacturing the resin molded product of the present invention can suppress the generation of burrs caused by the overflow of molten resin during insert molding.

FIG. 2 is an exploded perspective view of an embodiment in which a resin molded product is embodied in a sensor device. 1 is a cross-sectional view of a sensor device according to an embodiment taken along its axial direction. FIG. 2 is a perspective view of an inner housing according to an embodiment. 4A is a front view showing the positional relationship between an inner housing and a fixed-type insert according to an embodiment, and FIG. 4B is a front view showing a state in which the inner housing is set in the fixed-type insert according to an embodiment. FIG. 4 is a cross-sectional view showing the mold in a closed state. FIG. FIG. 4 is a perspective view showing a contact state between an inner housing and a slide core according to the embodiment. FIG. 4 is a front view showing a contact state between an inner housing and a slide core according to the embodiment. 9 is a cross-sectional view taken along line 9-9 in FIG. 8 . FIG. 4 is a side view of the inner housing according to the embodiment, seen from the base side. FIG. 2 is a perspective view of an inner housing according to an embodiment. 1A is a cross-sectional view corresponding to the previous Figure 9 and showing the gap between the base and slide core of an inner housing of one embodiment set in a mold during the manufacturing process of a sensor device; FIG. 1B is a cross-sectional view corresponding to the previous Figure 9 and showing the behavior of molten resin injected into the cavity of a mold in which an inner housing of one embodiment is set during the manufacturing process of a sensor device;

An embodiment in which the resin molded product is embodied in a sensor device will be described below.
As shown in Fig. 1, the sensor device 10 is provided on a rotating shaft 11 to be detected. The rotating shaft 11 has an input shaft 12, a torsion bar 13, and an output shaft 14. The input shaft 12 and the output shaft 14 are connected to each other via the torsion bar 13. The input shaft 12, the torsion bar 13, and the output shaft 14 are located on the same axis O. The rotating shaft 11 is, for example, a pinion shaft of a rack-and-pinion mechanism that constitutes a steering device of a vehicle. A steering wheel is connected to this pinion shaft via a steering shaft.

The sensor device 10 is a torque angle sensor that has both a torque detection function that detects the torque applied to the rotating shaft 11 through the operation of the steering wheel, and a rotation angle detection function that detects the rotation angle of the rotating shaft 11 over multiple rotations exceeding 360 degrees.

The sensor device 10 includes a permanent magnet 21 , a magnetic yoke 22 , a substrate 23 , a subassembly 24 , a sensor housing 25 , and a cover 26 .
The permanent magnet 21 has a cylindrical shape. The permanent magnet 21 is magnetized so that S poles and N poles are alternately arranged along the circumferential direction of the permanent magnet 21. The permanent magnet 21 is fixed to the outer circumferential surface of the input shaft 12.

The magnetic yoke 22 is cylindrical. A permanent magnet 21 is inserted inside the magnetic yoke 22. The magnetic yoke 22 is formed by molding two annular yokes 31, 32 made of a magnetic material with a synthetic resin material. The two yokes 31, 32 are aligned in a direction along the axis O of the rotating shaft 11. The part of the magnetic yoke 22 made of a synthetic resin material functions as a holder 33 that maintains the positional relationship between the two yokes 31, 32. A main driving gear 34 is integrally molded on the outer circumferential surface of this holder 33. The magnetic yoke 22 is fixed to the output shaft 14.

The two yokes 31, 32 each have a number of teeth 31a, 32a that are equally spaced along the circumferential direction. These teeth 31a, 32a extend in opposite directions along the axis O of the rotating shaft 11. The two yokes 31, 32 are held so that the teeth 31a, 32a are alternately positioned in the circumferential direction. The two yokes 31, 32 are arranged so that the circumferential centers of the teeth 31a, 32a coincide with the boundary between the north pole and south pole of the permanent magnet 21 when no torsional deformation is occurring in the torsion bar 13.

The substrate 23 is in the form of a rectangular plate. Three support holes 41 are provided in a row near the center of the substrate 23. The substrate 23 is also provided with a plurality of terminal connection holes 42. These terminal connection holes 42 are arranged in two rows along one of the two long side edges of the substrate 23. On one of the two opposite faces of the substrate 23, for example the upper face, two magnetic sensors 43, 44 for detecting the rotation angle of the rotating shaft 11 and two magnetic sensors 45, 46 for detecting the torque applied to the rotating shaft 11 are provided. These magnetic sensors 43, 44 for angle detection and the magnetic sensors 45, 46 for torque detection are arranged in a row along the long side edge of the substrate 23 opposite to the terminal connection holes 42. The two magnetic sensors 45, 46 for torque detection are located between the two magnetic sensors 43, 44 for angle detection in the direction along the long side edge of the substrate 23. Hall sensors, for example, are used as the angle detection magnetic sensors 43, 44 and the torque detection magnetic sensors 45, 46.

The subassembly 24 is a component for detecting the rotation angle of the rotating shaft 11 and a component for detecting the torque applied to the rotating shaft 11, which are attached to a holder 71 so that they can be handled as a single unit. The holder 71 is made of synthetic resin material and has a rectangular parallelepiped shape with one side open. Inside the holder 71, two driven gears 72 and 73 are rotatably mounted as components for detecting the rotation angle of the rotating shaft 11. The two driven gears 72 and 73 have different numbers of teeth. The teeth of the two driven gears 72 and 73 are slightly exposed to the outside through the opening of the holder 71. The two driven gears 72 and 73 are each provided with a disk-shaped permanent magnet (not shown). In addition, the holder 71 is provided with a core (not shown), which is a magnetic collector, as a component for detecting the torque applied to the rotating shaft 11. The core is integrally mounted with the holder 71 by resin molding.

The sensor housing 25 is integrally molded from a synthetic resin material. The sensor housing 25 has an outer housing 25A and a cylindrical inner housing 25B. The inner housing 25B is insert molded into the outer housing 25A. The sensor housing 25 is cylindrical with an opening in a direction intersecting the axis O of the rotating shaft 11. The rotating shaft 11 passes through the sensor housing 25. The sensor housing 25 also contains a permanent magnet 21, a magnetic yoke 22, a substrate 23, and a subassembly 24.

The sensor housing 25 has a circular insertion hole 51, a cylindrical first storage chamber 52, and a second storage chamber 53. The insertion hole 51, the first storage chamber 52, and the second storage chamber 53 are mutually connected. The insertion hole 51 and the first storage chamber 52 are located on the same axis O. The inner diameter of the insertion hole 51 is set to a value slightly larger than the outer diameter of the rotating shaft 11. The inner diameter of the first storage chamber 52 is set to a value slightly larger than the outer diameter of the magnetic yoke 22. Incidentally, the inner peripheral surface of the inner housing 25B constitutes a part of the inner peripheral surface of the first storage chamber 52. The second storage chamber 53 opens in a direction intersecting the axis O. The opening 53a of the second storage chamber 53 is closed by the cover 26.

Three stepped cylindrical support protrusions 54 are provided on the inner bottom surface of the second storage chamber 53. The three support protrusions 54 are aligned in a row along the width direction of the second storage chamber 53, which is a direction perpendicular to the axis O. The three support protrusions 54 correspond to the three support holes 41 provided in the base plate 23.

A number of terminals 55 protrude from the inner bottom surface of the second storage chamber 53. The terminals 55 are located outside the support protrusion 54 in the opening direction of the second storage chamber 53. The terminals 55 are arranged in two rows along the width direction of the second storage chamber 53. The terminals 55 correspond to the terminal connection holes 42 provided in the substrate 23.

A square tubular connector fitting portion 56 is provided on the outer bottom surface of the second storage chamber 53. The connector fitting portion 56 extends along the axis O of the rotating shaft 11. Inside the connector fitting portion 56, multiple terminals 55 are exposed by penetrating the bottom wall of the second storage chamber 53. A wiring connector (not shown) that electrically connects between the terminals 55 of the board 23 and an external device is fitted into the connector fitting portion 56. The external device is, for example, a steering device control device.

In the sensor housing 25, two C-shaped magnetic flux collecting rings 61, 62 are provided on the inner peripheral surface of the first storage chamber 52. These magnetic flux collecting rings 61, 62 are aligned in a direction along the axis O of the rotating shaft 11. The magnetic flux collecting ring 61 corresponds to the yoke 31 of the magnetic yoke 22, and the magnetic flux collecting ring 62 corresponds to the yoke 32 of the magnetic yoke 22. The magnetic flux collecting ring 61 is provided with two magnetic flux collecting protrusions 61a, 61b. These magnetic flux collecting protrusions 61a, 61b are exposed inside the second storage chamber 53. The two magnetic flux collecting protrusions 61a, 61b correspond to two magnetic flux collecting protrusions (not shown) of a core, which is a magnetic flux collecting member, provided in the subassembly 24.

As shown in FIG. 2, when the sensor device 10 is assembled, the sensor housing 25 is attached to a housing that rotatably supports the rotating shaft 11 to be detected, in this case, a gear housing 15 that houses a rack-and-pinion mechanism that constitutes the steering device of the vehicle. The first storage chamber 52 of the sensor housing 25 houses the magnetic yoke 22 attached to the rotating shaft 11. The second storage chamber 53 of the sensor housing 25 houses the board 23 and the subassembly 24.

The substrate 23 is attached to the inner bottom surface of the second storage chamber 53. Two magnetic sensors 43, 44 for angle detection and two magnetic sensors 45, 46 for torque detection (not shown) are provided on the upper surface of the substrate 23, i.e., on the surface opposite to the inner bottom surface of the second storage chamber 53. Although not shown, each support hole 41 of the substrate 23 is penetrated by each support protrusion 54 provided on the inner bottom surface of the second storage chamber 53. This restricts the substrate 23 from moving relative to the inner bottom surface of the second storage chamber 53. In addition, each terminal 55 protruding from the inner bottom surface of the second storage chamber 53 is penetrated by each terminal connection hole 42 of the substrate 23. Each terminal 55 is joined to the substrate 23 by soldering. The wiring pattern (not shown) of the substrate 23 and each terminal 55 are electrically connected.

The partial assembly 24 is attached inside the second storage chamber 53 in a manner overlapping the substrate 23. The two driven gears 72, 73 exposed from the holder 71 of the partial assembly 24 mesh with the main gear 34 provided on the magnetic yoke 22 inside the first storage chamber 52. Therefore, when the rotating shaft 11 rotates, the main gear 34 rotates integrally, and the two driven gears 72, 73 also rotate accordingly. The two driven gears 72, 73 have different numbers of teeth. Therefore, when the main gear 34 rotates in conjunction with the rotation of the rotating shaft 11, the rotation angles of the two driven gears 72, 73 relative to the rotation angle of the main gear 34 are different values.

The permanent magnets 72a, 73a provided on the driven gears 72, 73 face the angle detection magnetic sensors 43, 44 provided on the substrate 23 in the direction along the axis O of the rotating shaft 11. The magnetic sensors 43, 44 generate electric signals corresponding to the change in the magnetic field caused by the rotation of the driven gears 72, 73. The steering device control device detects the rotation angle of the rotating shaft 11 based on the electric signals generated by the magnetic sensors 43, 44. Since the rotation angle of the driven gear 72 relative to the driving gear 34 and the rotation angle of the driven gear 73 relative to the driving gear 34 are different from each other, the phases of the electric signals generated by the angle detection magnetic sensors 43, 44 are different from each other. The steering device control device calculates the rotation angle of the rotating shaft 11, which is more than 360°, in absolute angle based on the electric signals generated by the angle detection magnetic sensors 43, 44.

A permanent magnet 21 is positioned inside the two yokes 31, 32 of the magnetic yoke 22. In the direction along the axis O of the rotating shaft 11, the magnetic collector ring 61 is held at a position corresponding to the yoke 31, and the magnetic collector ring 62 is held at a position corresponding to the yoke 32. The magnetic collector ring 61 surrounds the periphery of the yoke 31, and the magnetic collector ring 62 surrounds the periphery of the yoke 32. The magnetic collector ring 61 induces magnetic flux from the yoke 31, and the magnetic collector ring 62 induces magnetic flux from the yoke 32.

The core 74 provided in the subassembly 24 is held at a position corresponding to the magnetic flux collecting ring 62 in the direction along the axis O of the rotating shaft 11. The core 74 is made by bending a metal plate having a predetermined contour shape. The core 74 has two arms (not shown) that extend in opposite directions along the circumferential direction of the magnetic yoke 22. These arms are held in close proximity to the outer circumferential surface of the magnetic flux collecting ring 62. The core 74 induces magnetic flux from the magnetic flux collecting ring 62.

The core 74 also has a first magnetic flux collecting protrusion and a second magnetic flux collecting protrusion, not shown. These first magnetic flux collecting protrusion and second magnetic flux collecting protrusion extend in a direction perpendicular to the axis O of the rotating shaft 11 in a direction away from the magnetic yoke 22, and are parallel to each other. The first magnetic flux collecting protrusion (not shown) of the core 74 and the magnetic flux collecting protrusion 61a of the magnetic flux collecting ring 61 face each other in a direction along the axis O of the rotating shaft 11. A magnetic sensor 45 for torque detection provided on the substrate 23 is interposed between the first magnetic flux collecting protrusion of the core 74 and the magnetic flux collecting protrusion 61a of the magnetic flux collecting ring 61. The second magnetic flux collecting protrusion of the core 74 and the magnetic flux collecting protrusion 61b of the magnetic flux collecting ring 61 face each other in a direction along the axis O of the rotating shaft 11. A torque detection magnetic sensor 46 is provided on the substrate 23 between the second magnetic flux collecting protrusion of the core 74 and the magnetic flux collecting protrusion 61b of the magnetic flux collecting ring 61. The torque detection magnetic sensors 45 and 46 detect the magnetic flux induced in the magnetic flux collecting rings 61 and 62 and the core 74.

When torque is applied to the input shaft 12 of the rotating shaft 11 through the operation of the steering wheel, causing the torsion bar 13 to twist and deform, a relative rotational displacement occurs between the input shaft 12 and the output shaft 14 in response to the torque applied to the input shaft 12. This changes the relative positions of the permanent magnet 21 and the magnetic yoke 22 in the rotational direction, as well as the relative positions of the permanent magnet 21 and the magnetic yoke 22 in the rotational direction. Accordingly, the magnetic flux induced from the permanent magnet 21 through the magnetic yoke 22 to the magnetic collector rings 61, 62 changes. The torque detection magnetic sensor 45 generates an electric signal corresponding to the magnetic flux leaking between the first magnetic collector protrusion of the core 74 and the magnetic collector protrusion 61a of the magnetic yoke 22. The torque detection magnetic sensor 46 generates an electric signal corresponding to the magnetic flux leaking between the second magnetic collector protrusion of the core 74 and the magnetic collector protrusion 61b of the magnetic yoke. The electrical signals generated by the torque detection magnetic sensors 45, 46 change depending on the torsional deformation of the torsion bar 13, i.e., the torsion angle of the torsion bar 13. The steering device control device calculates the torque acting on the torsion bar 13 based on the electrical signals generated by the torque detection magnetic sensors 45, 46.

Next, the configuration of the inner housing 25B will be described.
As shown in Fig. 3, magnetic flux collecting rings 61, 62 are insert molded into the inner housing 25B. The inner housing 25B has a cylindrical insertion portion 81 with both ends open and a rectangular plate-like base 82. The base 82 protrudes from the outer circumferential surface of the insertion portion 81. The base 82 is also provided in a direction perpendicular to the axial direction of the inner housing 25B. Two magnetic flux collecting protrusions 61a, 61b are exposed on the upper surface of the base 82.

An opening 81a is provided in the peripheral wall of the insertion portion 81. The opening 81a is provided in a portion of the insertion portion 81 that corresponds to the base 82 in the circumferential direction. The opening 81a is also provided in an upper portion of the insertion portion 81 that is based on the base 82. When the inner housing 25B is viewed from the opening 81a side, a reinforcing member 81b is provided in the center of the opening 81a in the circumferential direction. The reinforcing member 81b is provided in a form that connects two inner wall surfaces that face each other in the axial direction of the inner housing 25B at the opening 81a.

Next, we will explain the manufacturing method of the sensor housing 25. The sensor housing 25 is manufactured by insert molding using the inner housing 25B as an insert. The inner housing 25B is molded in advance in a separate process.

As shown in FIG. 4(a), the inner housing 25B is set in the mold. Specifically, first, the inner housing 25B is attached to a nest 92 provided on the upper surface of a fixed mold 91 in the mold. The nest 92 has an insertion portion 92a and a flange 92b. The insertion portion 92a is cylindrical. The insertion portion 81 of the inner housing 25B is fitted into the outer periphery of the insertion portion 92a. The flange 92b is an annular portion provided on the outer periphery of the base end of the insertion portion 92a, and is fixed to the upper surface of the fixed mold 91. As shown in FIG. 4(b), the inner housing 25B is inserted into the insertion portion 92a until its lower end abuts against the upper surface of the flange 92b. When the inner housing 25B is set in the fixed mold 91, a gap is formed between the lower surface of the base 82 of the inner housing 25B and the upper surface of the flange 92b.

Next, the mold is closed as shown in FIG. 5. That is, the movable mold 93 is closed relative to the fixed mold 91. The slide core 94 is advanced to a predetermined advanced position along a direction (left-right direction in FIG. 5) perpendicular to the opening and closing direction (up-down direction in FIG. 5) of the movable mold 93 relative to the fixed mold 91. This brings the mold including the fixed mold 91, the movable mold 93, and the slide core 94 into a closed state. When the mold is closed, a cavity 95, which is a space corresponding to the external shape of the outer housing 25A, is formed inside the mold. Incidentally, the slide core 94 is used to mold the second housing chamber 53 including the connector fitting portion 56 of the sensor housing 25.

As shown in FIG. 6, the slide core 94 has a first core portion 101 and a second core portion 102. The first core portion 101 has a space portion 103. The space portion 103 is open to the tip side along the forward direction of the first core portion 101 and to the lower side along a direction perpendicular to the forward direction. Incidentally, the space portion 103 is provided to avoid interference between the slide core 94 and a plurality of terminals 55 protruding from the inner bottom surface of the second housing chamber 53 when the slide core 94 is retracted after molding of the sensor housing 25 is completed.

The tip of the first core portion 101 is provided with a curved surface 104. The curved surface 104 is curved to correspond to the outer peripheral surface of the inner housing 25B. The curved surface 104 is provided from the viewpoint of closing the opening 81a of the inner housing 25B when the mold is closed. The curved surface 104 is provided with a recess 104a, which is a concave portion into which the reinforcing member 81b fits, and closing portions 104b, 104b that fit into the opening 81a divided into two by the reinforcing member 81b to close the opening 81a.

The boundary between the second core portion 102 and the first core portion 101 is provided with an inclined surface 102a. The inclined surface 102a is provided to correspond to the inclination of the opening edge of the second storage chamber 53 in the sensor housing 25. As shown in FIG. 7, the second core portion 102 is provided with an insertion hole 102b penetrating therethrough. The insertion hole 102b extends along the axis of the inner housing 25B in a direction perpendicular to the movement direction of the slide core 94. The insertion hole 102b and the space portion 103 of the first core portion 101 communicate with each other. The insertion hole 102b is a portion into which a movable nest (not shown) is inserted to integrally mold the connector fitting portion 56 including the multiple terminals 55 with the outer housing 25A.

As shown in FIG. 7, when the mold is closed, the tip of the first core portion 101 of the slide core 94 is maintained in contact with the outer peripheral surface of the inner housing 25B. The opening 81a of the inner housing 25B is covered by the tip of the first core portion 101. Also, as shown in FIG. 5, when the mold is closed, the lower surface of the first core portion 101 of the slide core 94 is maintained in contact with the upper surface of the base 82 of the inner housing 25B.

Next, molten resin is injected into the cavity 95 formed inside the mold. Molten resin refers to synthetic resin material that has been heated and melted. The molten resin is injected into the cavity 95 through a gate 93a (see FIG. 5) provided at the top of the movable mold 93. After the cavity 95 is filled with the molten resin, the filled molten resin is cooled and solidified. Thereafter, the slide core 94 is retracted to a set retracted position and the movable mold 93 is separated from the fixed mold 91 to open the mold, and the sensor housing 25, which is a resin molded product, is removed. This results in the sensor housing 25 shown in FIG. 1 being obtained.

With the above, the manufacturing of the sensor housing 25 is completed.
Here, in the manufacturing process of the sensor housing 25, the following concerns arise.
As shown in Fig. 8 and Fig. 9, when the mold is closed, a gap δ1 may be formed between the upper surface of the base 82 of the inner housing 25B and the lower surface of the first core portion 101 of the slide core 94 due to the dimensional tolerance of the inner housing 25B. However, in Fig. 8 and Fig. 9, the gap δ1 is exaggerated for convenience of explanation. Also, as shown in Fig. 9, the width of the base 82 (the length in the left-right direction in Fig. 9) is set to be shorter than the width of the first core portion 101 of the slide core 94. Also, a space portion 103 is provided inside the slide core 94 to avoid interference with the terminal 55 of the connector fitting portion 56. Therefore, when molten resin is injected into the cavity 95 inside the mold, the molten resin may leak into the space portion 103 of the slide core 94 through the gap δ1.

Therefore, in this embodiment, the following shape is adopted as the shape of the inner housing 25B.
As shown in Fig. 10, the base 82 of the inner housing 25B has three side surfaces 82a, 82b, and 82c in addition to an upper surface 82u and a lower surface 82l. The side surfaces 82a and 82b face each other in a direction perpendicular to the axial direction of the inner housing 25B (the left-right direction in Fig. 10). The side surface 82c is a tip surface that is an end surface opposite to the insertion portion 81 of the base 82, and is perpendicular to the two side surfaces 82a and 82b. In addition, an inclined surface 111 is provided at each corner between the side surface 82a and the lower surface 82l, and at each corner between the side surface 82b and the lower surface 82l. These inclined surfaces 111 are inclined so as to approach each other as they move downward, which is the direction from the upper surface 82u side to the lower surface 82l side. As shown in FIG. 11, the inclined surfaces 111 are provided over the entire length of the side surfaces 82a, 82b, in other words, over the entire length of the base 82 in the direction in which the base 82 protrudes relative to the outer circumferential surface of the insertion portion 81.

According to this configuration, the following effects are obtained when manufacturing the sensor housing 25.
As shown in Fig. 12(a), inside the mold, a gap δ1 is formed between an upper surface 82u of the base 82 of the inner housing 25B and a lower surface of the first core portion 101 of the slide core 94. However, in Fig. 12(a), for the sake of convenience, the gap δ1 is exaggerated. In addition, a gap δ2 is also formed between a lower surface 82l of the base 82 and a flange 92b of the insert 92 in the fixed mold 91. When molten resin is injected into a cavity 95 provided inside the mold in this state, the molten resin behaves as follows.

As shown in FIG. 12B, the molten resin flowing in from the top of the inner housing 25B flows from the top to the bottom inside the cavity 95. A part of the molten resin flows through the side of the first core portion 101 of the slide core 94 into the space below the pedestal 82 of the inner housing 25B, that is, into the gap δ2 between the pedestal 82 and the flange 92b of the insert 92 in the mold. At this time, since the two inclined surfaces 111, 111 of the pedestal 82 are inclined so as to approach each other as they go downward, a part of the molten resin flowing from the top to the bottom of the pedestal 82 is guided by the two inclined surfaces 111, 111 toward the gap δ2, which is the space below the pedestal 82. This makes it easier for the molten resin to flow into the gap δ2 below the pedestal 82. The pressure of the molten resin flowing into the gap δ2 between the pedestal 82 and the flange 92b of the insert 92 pushes the pedestal 82 up toward the bottom surface of the first core portion 101. As a result, the top surface 82u of the pedestal 82 is pressed against the bottom surface of the first core portion 101, eliminating the gap δ1 between the top surface 82u of the pedestal 82 and the bottom surface of the first core portion 101. This prevents the molten resin from leaking into the space 103 of the slide core 94 through the gap δ1.

The upper surface 82u of the base 82 is the surface into which the molten resin flows during insert molding and is maintained in contact with the mold, and constitutes a first surface that is exposed to the second storage chamber 53, which is the internal space of the sensor housing 25, without being covered by resin when molding is completed. The lower surface 82l of the base 82 is the surface opposite the upper surface 82u of the base 82 and constitutes a second surface that is maintained in a state in which a gap is formed between the upper surface 82u and the mold during insert molding and is covered by resin when molding is completed. The three side surfaces 82a, 82b, and 82c connect the upper surface 82u and the lower surface 82l of the base 82 to each other and constitute a third surface that is covered by resin when molding is completed. The two inclined surfaces 111 are surfaces that guide the molten resin injected during insert molding from the upper surface 82u side to the lower surface 82l side, and constitute a fourth surface that is covered by resin when molding is completed.

Therefore, according to this embodiment, the following effects can be obtained.
(1) During insert molding of the sensor housing 25, the pressure of the molten resin injected into the cavity 95 of the mold is used to press the base 82 of the inner housing 25B against the slide core 94 to bring them into contact with it. This narrows the gap δ1 between the base 82 of the inner housing 25B and the first core portion 101 of the slide core 94. This makes it possible to prevent the molten resin from leaking into the space portion 103 of the slide core 94 through the gap δ1. This also makes it possible to prevent burrs from being generated in the sensor housing 25, which is a resin molded product. This makes it possible to reduce finishing work such as deburring. This also makes it possible to maintain and improve the quality of the sensor housing 25.

(2) The base 82 of the inner housing 25B is provided with two inclined surfaces 111, 111 as a configuration for facilitating flow of molten resin into the gap δ2 below the base 82 during insert molding of the sensor housing 25. The inclined surface 111 is provided at the corner between the side surface and the bottom surface of the base 82, i.e., on the part of the base 82 opposite the direction in which the molten resin flows. Since the two inclined surfaces 111, 111 are inclined so as to approach each other downward, the molten resin is guided by the two inclined surfaces 111, 111 toward the gap δ2 below the base 82. This makes it easier for the molten resin to flow into the gap δ2 below the base 82.

(3) The inclined surface 111 is provided over the entire length of the insertion portion 81 of the base 82 in the protruding direction relative to the outer circumferential surface. This makes it even easier for the molten resin to flow into the gap δ2 below the base 82.

(4) When insert molding the sensor housing 25, the pressure of the molten resin injected into the cavity 95 of the mold is used to eliminate the gap δ1 between the base 82 and the slide core 94. For this reason, it is only necessary to provide, for example, an inclined surface 111 for guiding the molten resin on the base 82 of the inner housing 25B. Therefore, there is no need to provide the mold with a special mechanism for eliminating the gap δ1 between the base 82 and the slide core 94.

<Other embodiments>
This embodiment may be modified as follows.
In this embodiment, the width of the base 82 (the length in the left-right direction in FIGS. 12(a) and 12(b)) is set to a length shorter than the width of the first core portion 101 in the slide core 94, but the width of the base 82 may be set to a length longer than the width of the first core portion 101 depending on the product specifications, etc. In this case, the portion of the upper surface of the base 82 that faces the first core portion 101 and protrudes from the first core portion 101 is covered with resin.

In the present embodiment, the inclined surface 111 is provided over the entire length of the side surfaces 82a, 82b. However, the inclined surface 111 may be provided only in a predetermined section of the side surfaces 82a, 82b.
In the present embodiment, the connector fitting portion 56 is integrally molded on the outer bottom surface of the second accommodation chamber 53, but the position at which the connector fitting portion 56 is formed may be changed depending on the product specifications of the sensor device 10. In addition, the connector fitting portion may be omitted depending on the product specifications, etc.

- Inside the mold, inclined surfaces 111 are provided at the corners between the underside 82l and the side 82a of the base 82 and at the corners between the underside 82l and the side 82a. However, depending on the product specifications of the sensor device 10 or the structure of the mold, inclined surfaces 111 may be provided around the entire corners between the underside 82l of the base 82 and the three side surfaces.

- In this embodiment, the base 82 is provided with two inclined surfaces 111, 111 to facilitate the flow of molten resin into the gap δ2 below the base 82 of the inner housing 25B, but curved surfaces may be provided instead of the inclined surfaces 111. Even in this case, it is preferable that the two curved surfaces be curved so that they approach each other as they extend downward.

- In this embodiment, the sensor housing 25 is given as an example of a resin molded product, but other resin molded products that utilize insert molding may also be used.

25...Sensor housing (plastic molded part)
25A...Outer housing 25B...Inner housing (insert)
53: Second storage chamber (space)
56: Connector fitting portion 81: First insert portion 82: Second insert portion 82u: Upper surface (first surface)
82l...Bottom surface (second surface)
82a, 82b, 82c...side surface (third surface)
111...inclined surface (fourth surface)

Claims (8)

A resin molded product having an internal space formed by insert molding an insert,
The insert has a first insert portion and a second insert portion provided so as to protrude from an outer surface of the first insert portion,
the second insert portion has a first surface having a portion exposed to the space without being covered with resin, a second surface which is a surface opposite to the first surface, is located downstream of the first surface in a flow direction of molten resin injected during insert molding, and is covered with resin, and a third surface which connects the first surface and the second surface to each other and is covered with resin;
A resin molded product, in which a fourth surface is provided at at least a portion of a corner between the second surface and the third surface, the fourth surface being configured to guide the molten resin flowing in from the first surface side from the first surface side to the second surface side. The resin molded product according to claim 1, wherein the fourth surface includes two inclined surfaces located on opposite sides of each other in a direction perpendicular to the protruding direction of the second insert portion relative to the outer surface of the first insert portion, and these inclined surfaces are inclined so as to approach each other from the first surface side toward the second surface side. The second insert portion has a rectangular plate shape,
3. The resin molded product according to claim 2, wherein the two inclined surfaces are provided over an entire length of the second insert portion in a protruding direction relative to the outer surface of the first insert portion. The resin molded product according to any one of claims 1 to 3, wherein a connector fitting portion, which is a portion into which a connector is fitted, is provided near the second insert portion. A method for manufacturing a resin molded product having an internal space, comprising the steps of:
The method includes the steps of: setting the insert inside a mold; and injecting molten resin into a cavity formed inside the mold.
The insert has a first insert portion and a second insert portion provided so as to protrude from an outer surface of the first insert portion,
the second insert portion has a first surface having a portion maintained in contact with the mold, a second surface which is a surface opposite to the first surface, located downstream of the flow direction of the molten resin with respect to the first surface and maintained in a state in which a gap is formed between the first surface and the mold, and a third surface which connects the first surface and the second surface with each other and is maintained in a state in which a gap is formed between the first surface and the mold,
A manufacturing method for a resin molded product, wherein a fourth surface is provided at at least a portion of a corner between the second surface and the third surface, which guides the molten resin flowing in from the first surface side from the first surface side to the second surface side. The method for manufacturing a resin molded product according to claim 5, wherein the fourth surface includes two inclined surfaces located on opposite sides of each other in a direction perpendicular to the protruding direction of the second insert portion relative to the outer surface of the first insert portion, and these inclined surfaces are inclined so as to approach each other from the first surface side toward the second surface side. The second insert portion has a rectangular plate shape,
The method for manufacturing a resin molded product according to claim 6, wherein the two inclined surfaces are provided over an entire length of the second insert portion in a protruding direction relative to the outer surface of the first insert portion. The method for manufacturing a resin molded product according to any one of claims 5 to 7, wherein a connector fitting portion, which is a portion into which a connector is fitted, is provided near the second insert portion.