JP6344043B2 - Sensor - Google Patents

Description

  The present invention includes a primary molded body in which a detection portion for detecting a change in magnetic flux to be detected is embedded in a tip portion, and a secondary molded body obtained by resin insert molding the primary molded body. The present invention relates to a sensor having a seal member on a part of an outer peripheral surface.

  Conventionally, as a sensor having the above-described configuration, for example, a rotation detection sensor that detects a rotation speed of an output shaft (detection target) of a wheel or a transmission is known (see Patent Document 1). The rotation detection sensor is required to increase the detection accuracy by accurately controlling the relative position between the detection target and the detection unit, that is, the position of the detection unit inside the sensor.

  The rotation detection sensor of Patent Document 1 (in the literature, an insert-molded product) includes a primary molded body (preliminary molded product in the literature) obtained by insert-molding a pre-inserted object in which a detection unit is embedded with a primary resin layer, and a primary molded body. And a secondary molded body (secondary resin layer in the literature) obtained by resin insert molding. When the rotation detection sensor is inserted and fixed in the through hole of the vehicle body side case, the gap between the vehicle body side case and the secondary molded body is sealed by the seal groove and the seal member formed on the outer peripheral surface of the secondary molded body. The

  Further, the side surface of the primary molded body has a plurality of protrusions facing in the radially outward direction on the detection part side from the seal member. These protrusions are formed in a concave shape at the tip, and when the primary molded body is insert-molded, the tip is brought into contact with a mold and positioned. Next, molten resin is poured into the cavity between the mold and the primary molded body, and the rotation detection sensor is manufactured. At this time, the circumferential mold in which the protrusion is located has a built-in heater, and the tip of the protrusion is dissolved by heating from the heater.

JP 2004-351801 A

  However, in the conventional rotation detection sensor, in order to melt the protrusions of the primary molded body, the contact with the mold is released in the state where the resin pressure of the molten resin is acting, and the detection unit inside the sensor There is a risk that a slight misalignment may occur. For this reason, there is room for improvement in improving the detection accuracy of the rotation detection sensor.

  By the way, depending on the vehicle body side case to which the rotation detection sensor is attached and the arrangement of the detection target, the axial length on the detection target side of the rotation detection sensor may be limited to be shorter than the vehicle body side case. In that case, the protrusion of the primary molded body and the seal groove formed on the outer peripheral surface of the secondary molded body may overlap in the radial direction.

  As a result, the amount of resin shrinkage of the portion that does not overlap the protrusion (thickness) in the seal groove of the secondary molded body is greater than the amount of resin shrinkage of the portion that overlaps the protrusion (thickness). Is likely to occur, resulting in a dimensional error and a reduction in sealing performance.

  On the other hand, it is also conceivable to form an annular protrusion on the side surface of the primary molded body and form a seal groove on the outer surface of the annular protrusion. In this case, the annular protrusion functions as a pressing portion at the time of insert molding. However, for example, it is necessary to provide two gates for pouring the molten resin on both sides of the annular protrusion, which is not efficient.

  Therefore, an object of the present invention is to provide a sensor capable of shortening the axial length while rationally improving detection accuracy and sealing performance.

  A characteristic configuration of the sensor according to the present invention includes: a primary molded body in which a detection portion that detects a change in magnetic flux to be detected is embedded in a tip portion, and a plurality of protrusions that are directed radially outward from a side surface; and the protrusion A secondary molded body obtained by resin insert molding the primary molded body in a state in which a part of the secondary molded body is exposed, and a region facing the radially outward direction with respect to at least a part of a portion where the protrusion is exposed. It is in the point provided with the cylindrical wall part integrally formed with the molded object, and the cyclic | annular sealing member arrange | positioned along the outer peripheral surface of the said cylindrical wall part.

  According to this configuration, the protrusion of the primary molded body serves as a pressing portion during insert molding. In order to hold down the pressing portion, a part of the insert mold is disposed. On the other hand, in such a sensor, a seal member that seals a gap between the vehicle body side case and the secondary molded body is disposed on the outer peripheral surface of the secondary molded body. Moreover, since the resin thickness which covers a detection part is restrict | limited small so that the detection accuracy of a detection part may be improved, the site | part in which a sealing member is arrange | positioned among secondary molded objects is the size of the front-end | tip part by which a detection part is embed | buried In many cases, the diameter is large.

  In consideration of the difference between the outer diameter size of the primary molded body defined by the protrusions serving as the pressing portion and the outer diameter size of the portion where the seal member is disposed, in this configuration, the diameter of the portion where the pressing portion is exposed. A cylindrical wall portion is formed on the outer side in the direction, and a seal member is provided on the outer peripheral surface of the cylindrical wall portion. Thereby, the position of the part where the protrusion is exposed overlaps with the position of the part where the seal member is disposed along the longitudinal direction (axial direction) of the sensor. Therefore, the length of the sensor can be shortened.

  Further, when the mold is brought into contact with the plurality of protrusions so as to insert-mold the primary molded body, the mold can be inserted into the internal space of the cylindrical wall portion. For this reason, since a primary molded object is insert-molded in the state where the position was fixed, the position shift of the detection part inside a sensor does not generate | occur | produce.

  Furthermore, since no resin is present in the internal space of the cylindrical wall portion, the thickness of the cylindrical wall portion can be made uniform and kept at a predetermined thickness. The resin filled in the wall portion has a small amount of shrinkage. Therefore, generation | occurrence | production of a void and sink marks can be suppressed and the resin amount required for shaping | molding of a secondary molded object can be reduced, improving the dimensional accuracy of the site | part by which a sealing member is arrange | positioned.

  As described above, it has been possible to provide a sensor capable of shortening the axial length while rationally increasing the detection accuracy and the sealing performance.

  Another characteristic configuration is that an inclined portion is formed on the bottom portion of the cylindrical wall portion so as to approach the detection portion side in the radially inward direction.

  As described above, in order to increase the detection accuracy of the detection unit, the thickness of the resin covering the detection unit is limited to be small, so the base end side of the sensor has a larger diameter than the front end side, and the gate has a base end with a large amount of resin. Set to the side. That is, the filling space of the molten resin flowing in from the gate is narrowed from the proximal end side toward the distal end side, and the resin flow is likely to be hindered.

  However, as in this configuration, by forming an inclined portion that approaches the detection portion side in the radial direction at the bottom of the cylindrical wall portion, the molten resin can flow smoothly to the detection portion on the tip side. Can do. Therefore, a short shot in which the resin surrounding the detection unit is insufficiently filled is prevented, and the detection unit can be reliably protected.

  Another characteristic configuration is that a seal groove portion in which the seal member is disposed is formed on the outer peripheral surface of the cylindrical wall portion.

  If the seal groove portion is formed on the outer peripheral surface of the cylindrical wall portion as in this configuration, the thickness of the portion where the seal member is disposed is set smaller than the surrounding thickness. Therefore, it is possible to reliably eliminate a dimensional error at a portion where the seal member is disposed and to exhibit a desired sealing function.

  In another characteristic configuration, the plurality of protrusions are formed at equal intervals along the outer periphery of the primary molded body, and the plurality of protrusions are in contact with a mold during the resin insert molding. In that it has a tip surface that is maintained.

  As in this configuration, by providing at least four protrusions at equal intervals along the outer periphery of the primary molded body, the abutting state of the mold is stabilized, so that the displacement of the detection portion inside the sensor can be reliably prevented. can do. Furthermore, as compared with the conventional case where the tip of the protrusion is formed in a concave shape and melted, the state where the protrusion and the mold are in surface contact is maintained, so that the position of the detection portion in the sensor is not displaced. Not likely to occur.

  Another characteristic configuration includes a rib portion formed integrally with the secondary molded body, and the rib portion includes an outer surface of the secondary molded body between the cylindrical wall portion and the plurality of protrusions. Are connected and extended in the axial direction of the cylindrical wall portion.

  If the rib portion is formed as in this configuration, a large flow area of the molten resin is ensured, so that the molten resin can be reliably spread to the detection portion. Furthermore, since the support strength with respect to the detection part with small thickness increases, detection accuracy can be maintained over a long period of time.

It is the whole perspective view which looked at the sensor from the detection part side. It is the whole perspective view which looked at the primary fabrication object from the detection part side. FIG. 3 is a sectional view taken along line III-III in FIG. 1. It is the bottom view which looked at the sensor from the detection part side. It is a schematic diagram which shows the state in which the sensor was set to the metal mold | die. It is a schematic diagram at the time of insert-molding a sensor.

  Hereinafter, an embodiment of a sensor according to the present invention will be described with reference to the drawings. In the present embodiment, a rotation detection sensor 1 that detects the rotation state of a vehicle wheel (detection target), for example, will be described as an example of the sensor. However, the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the invention.

  FIG. 1 is an overall perspective view of the rotation detection sensor 1 according to the present embodiment as viewed from the Hall IC 10 (an example of a detection unit), and FIG. 2 is an overall view of the primary molded body 20 as viewed from the Hall IC 10 side. It is a perspective view. 3 is a cross-sectional view taken along the line III-III of FIG. 1, and FIG. 4 is a bottom view of the rotation detection sensor 1 viewed from the Hall IC 10 side. In FIG. 1, the Hall IC 10 side will be described as the lower side, and the opposite side as the upper side.

[Basic configuration]
As shown in FIG. 3, the rotation detection sensor 1 in the present embodiment is fixed to the vehicle body side case 2, and the Hall IC 10 is disposed to face the rotation wheel 3 provided in the vehicle as a detection target. The rotating wheel 3 is a ring-shaped gear rotor that is attached to an output shaft of a transmission, an axle of a wheel, and the like and rotates integrally. The rotation of the rotating wheel 3 together with the output shaft and the axle causes a change in magnetic flux. The rotation detection sensor 1 detects the change of the magnetic flux, thereby detecting the rotation state of the output shaft and wheels of the transmission.

  As shown in FIG. 1-3, the rotation detection sensor 1 includes a cylindrical primary molded body 20 in which the Hall IC 10 is embedded in the tip end portion 20a, and a cylindrical secondary formed by resin-molding the primary molded body 20. A molded body 30 and a seal member 40 disposed along the outer peripheral surface of the secondary molded body 30 are provided.

  As shown in FIG. 2, the Hall IC 10 is electrically connected to the wire 13 of the cable 12 via the terminal 11. That is, the rotation detection sensor 1 converts the change in the magnetic flux of the rotating wheel 3 detected by the Hall IC 10 into an electric signal and outputs it.

  The primary molded body 20 is configured by insert molding the Hall IC 10 and the terminal 11 with a resin. In addition, four lower protrusions 21 (an example of protrusions) are formed below the primary molded body 20 so as to face radially outward from the side surfaces. Furthermore, two upper protrusions 22 are formed above the primary molded body 20 so as to face radially outward from the side surfaces.

  The lower protrusion 21 in the present embodiment is composed of two first lower protrusions 21a having a rectangular cross section, and two second lower protrusions 21b having a truncated cone shape having a tip area smaller than that of the first lower protrusion 21a. The A cavity number or the like is stamped on the rectangular front end surface of the first lower protrusion 21a, so that the arrangement direction with respect to the insert molding die 50 can be easily confirmed.

  The two first lower protrusions 21 a are provided to face each other in the radial direction of the primary molded body 20. Similarly, the two second lower protrusions 21 b are also provided to face each other in the radial direction of the primary molded body 20. Further, the first lower protrusions 21 a and the second lower protrusions 21 b are arranged at equal intervals along the circumferential direction of the primary molded body 20.

  Two upper protrusions 22 are formed in the same direction as the first lower protrusion 21 a with respect to the axial direction of the primary molded body 20. Although details will be described later, the lower protrusion 21 and the upper protrusion 22 are held in contact with the mold 50, and the position of the primary molded body 20 is fixed at the time of insert molding.

  As shown in FIGS. 1 and 3, the secondary molded body 30 includes a front end portion 31 that accommodates the Hall IC 10, an intermediate portion 32 that is inserted and fixed in the through hole 2 a of the vehicle body side case 2, the terminal 11, and the cable 12. And a base end portion 33 in which the tip end portion is accommodated. By setting the primary molded body 20 in the mold 50 and insert molding with resin, the secondary molded body 30 surrounding the primary molded body 20 is formed.

  Since the Hall IC 10 is embedded, the tip portion 31 is set to have a small thickness so as not to hinder the flow of magnetic flux. Thereby, the detection accuracy of the Hall IC 10 can be increased.

  As shown in FIG. 1, the base end portion 33 is formed by exposing the distal end surface and the side surface of the upper protrusion 22, and is formed with an arm portion 39 that extends radially outward to receive the distal end portion of the cable 12. Has been. As will be described in detail later, the upper protrusion 22 is held in contact with the mold 50, and the position of the primary molded body 20 is fixed during insert molding.

  The intermediate portion 32 of the secondary molded body 30 is formed on a cylindrical wall portion 34 formed in a region where a part of the exposed portion 21 c of the lower protrusion 21 faces in the radially outward direction, and an outer peripheral surface of the cylindrical wall portion 34. An annular seal groove 35 and a bracket 36 formed to extend radially outward are provided. Further, the secondary molded body 30 is insert-molded in a state in which the tip surface and a part of the side surface of the first lower protrusion 21a are exposed and the tip surface of the second lower protrusion 21b is exposed. That is, the secondary molded body 30 is configured by resin insert molding the primary molded body 20 with a part of the lower protrusion 21 exposed.

  In the rotation detection sensor 1, the seal member 40 is disposed in the seal groove portion 35 of the intermediate portion 32. In particular, in the present embodiment, as shown in FIG. 3, the seal groove portion 35 is radially outward with respect to the outer peripheral surface of the cylindrical wall portion 34, that is, the internal space from the bottom of the cylindrical wall portion 34 to the opening end. It is formed in the position which opposes. In addition, an inclined portion 34 a that approaches the Hall IC 10 side in the radial direction is formed at the bottom of the cylindrical wall portion 34.

  Further, as shown in FIGS. 1 and 4, four rib portions 38 extending in the axial direction of the cylindrical wall portion 34 are integrally formed with the secondary molded body 30 inside the cylindrical wall portion 34. ing. The rib portion 38 is formed by connecting the outer peripheral wall of the cylindrical wall portion 34 and the outer surface of the secondary molded body 30 between the plurality of lower protrusions 21, and approaches the Hall IC 10 side in the radially inward direction. An inclined portion 38a is formed. Although details will be described later, when the primary molded body 20 is insert-molded by the inclined portion 34a provided at the bottom of the cylindrical wall portion 34 or the inclined portion 38a of the rib portion 38, the molten resin smoothly flows to the tip portion 31. To do. Therefore, the molten resin reaches the tip portion 31 with a small thickness, and short shots in which the tip portion 31 is insufficiently filled with resin are prevented. Further, the rib portion 38 can increase the strength of the tip portion 31 formed thin.

  Further, as shown in FIG. 3, since the seal groove 35 is formed on the outer peripheral surface of the cylindrical wall 34 provided in the intermediate portion 32, the inside of the seal groove 35 serving as the internal space of the cylindrical wall 34 is formed. There is no resin. That is, it becomes possible to reduce the thickness of the seal groove 35 and form it uniformly, the resin is quickly solidified to prevent the occurrence of sink marks and voids, and the amount of shrinkage of the resin is made uniform, so that the seal groove The dimensional accuracy of 35 increases.

  A metal bolt fixing portion 36 a is fitted in the hole portion of the bracket 36. By fixing the bolt 4 to the vehicle body side case 2 while being inserted into the bolt fixing portion 36a, the separation distance of the rotation detection sensor 1 from the rotating wheel 3 is set to a predetermined distance. Therefore, in order to increase the detection accuracy of the rotation detection sensor 1, it is important to increase the relative position between the rotation wheel 3 and the Hall IC 10, that is, the position accuracy of the Hall IC 10 inside the rotation detection sensor 1.

[Insert molding]
Next, a resin molding method for the rotation detection sensor 1 having the above-described configuration will be described with reference to FIGS. 2 and 5-6.

  As shown in FIG. 2, insert molding is performed using a resin in a state where the Hall IC 10 and the terminal 11 are connected to form a primary molded body 20. Next, on the base end side of the primary molded body 20, the wire 13 of the cable 12 is snap-fitted to the claw portion 11 a formed on the terminal 11 while being connected to the terminal 11 by soldering or the like.

  Next, as shown in FIG. 5, the mold 50 is set on the primary molded body 20. At that time, the upper mold 52 is positioned so as to come into contact with the tip surface and the side surface of the upper protrusion 22 of the primary molded body 20. Further, the lower mold 51 is assembled to the upper mold 52 while being brought into contact with the lower protrusion 21 of the primary molded body 20. The lower mold 51 is provided with a slide core 51a at a site where the seal groove portion 35 of the secondary molded body 30 is formed. In the present embodiment, the two upper protrusions 22 and the two first lower protrusions 21a that are in contact with the mold 50 are disposed on the same axis, and are provided to face each other in the radial direction. Positioning with respect to the metal mold | die 50 of the primary molded object 20 is performed reliably.

  Next, as shown in FIG. 6, molten resin is injected from a gate G provided above the upper mold 52, and the primary molded body 20 is insert-molded with the resin. As a result, the secondary molded body 30 surrounding the primary molded body 20 is formed.

  The molten resin flowing in from the gate G flows in the order of the base end portion 33, the intermediate portion 32, and the tip end portion 31 of the secondary molded body 30. In particular, since the molten resin filling space becomes narrower toward the detection unit 10 with the cylindrical wall portion 34 as a boundary, the molten resin does not flow smoothly from the base end portion 33 to the tip end portion 31. However, in this embodiment, since the inclined portion 34 a is provided at the bottom of the cylindrical wall portion 34, the molten resin can smoothly flow in the direction of the tip portion 31. Further, as shown in FIG. 1, a large amount of molten resin can be caused to flow in the direction of the distal end portion 31 by the rib portion 38 that communicates the outer peripheral wall of the cylindrical wall portion 34 and the distal end portion 31. Further, since the inclined portion 38 a is provided in the rib portion 38, the molten resin tends to flow smoothly in the direction of the tip portion 31.

  In the present embodiment, when the primary molded body 20 is insert-molded, the state where the tip surfaces of the lower protrusion 21 and the upper protrusion 22 are in surface contact with the mold 50 is maintained. That is, even when the resin pressure of the molten resin flowing in from the gate G is received, the four lower protrusions 21 and the two upper protrusions 22 arranged at equal intervals continue to contact the mold 50, and thus the primary molded body 20. Prevents tilting. In particular, since the large contact area between the tip surface of the first lower protrusion 21 a and the mold 50 is ensured, the primary molded body 20 is firmly fixed to the mold 50. Further, even if the resin pressure is applied in the direction of the side surfaces of the two first lower protrusions 21a, the tip surface of the second lower protrusion 21b is in contact with the lower mold 51, so that the primary molded body 20 is prevented from moving. The Therefore, the Hall IC 10 has high positional accuracy inside the rotation detection sensor 1.

  Next, the mold 50 is released and the resin is solidified, whereby the rotation detection sensor 1 is completed. In that case, since the solidification speed | rate of resin is so slow that the site | part with larger thickness among the secondary molded objects 30, shrinkage | contraction amount is large and a void and sink are easy to generate | occur | produce. However, in this embodiment, since the seal groove part 35 is formed in the cylindrical wall part 34, the thickness of the seal groove part 35 can be made small and uniform.

  As a result, the resin in the seal groove portion 35 is solidified without any difference in shrinkage, so that a dimensional error in the seal groove portion 35 hardly occurs. Further, since the thickness of the seal groove 35 is small, there is no possibility that voids or sink marks are generated. Therefore, a desired sealing function can be exhibited by the seal member 40 interposed between the vehicle body side case 2 and the seal groove portion 35.

[Other Embodiments]
(1) In the above-described embodiment, the four lower protrusions 21 and the two upper protrusions 22 that protrude from the side surface of the primary molded body 20 are provided. However, the number of the lower protrusions 21 may be two or three or more. The upper protrusion 22 may not be provided. In particular, it is preferable to provide a plurality of lower protrusions 21 at equal intervals so as to contact the lower mold 51 in a balanced manner.
(2) In the above-described embodiment, the cylindrical wall portion 34 is disposed in a region where a part of the exposed portion 21c of the lower protrusion 21 faces, but the tubular portion is formed in a region where all of the exposed portion 21c of the lower protrusion 21 faces. The wall 34 may be disposed. In this case, the length of the rotation detection sensor 1 can be further shortened.
(3) In the above-described embodiment, the inclined portion 34a is provided at the bottom of the cylindrical wall portion 34. However, the inclined portion 34a may not be provided and may be formed horizontally.
(4) In the above-described embodiment, the seal groove portion 35 is provided on the outer peripheral surface of the cylindrical wall portion 34. However, an annular seal groove portion 35 is provided along the inner peripheral surface of the portion where the through hole 2a of the vehicle body side case 2 is located. May be provided.
(5) In the above-described embodiment, the inclined portions 38a are provided in the four rib portions 38 positioned between the plurality of lower protrusions 21. However, the inclined portions 38a need not be provided, and the arrangement of the rib portions 38 is not necessary. There is no particular limitation on the quantity. Further, the rib portion 38 may be omitted.
(6) In the above-described embodiment, the primary molded body 20 and the secondary molded body 30 are formed in a circular shape when viewed in cross section, but may be formed in a polygonal shape when viewed in cross section, and is not particularly limited.
(7) In the above-described embodiment, the Hall IC 10 is configured to be electrically connected to the wire 13 of the cable 12 via the terminal 11, but the rotation detection sensor 1 is provided with a part of the terminal 11 at the opening end. It may be configured as an exposed socket, and the rotation detection sensor 1 and the connector may be electrically connected.
(8) Although the sensor in the present invention has been described as the rotation detection sensor 1, it is needless to say that the sensor can be used for a sensor that detects the position of a linear motion such as a rack.

  The sensor according to the present invention can be used for various sensors such as a rotation detection sensor.

1 Rotation detection sensor (sensor)
3 Rotating wheel (detection target)
10 Hall IC (detector)
20 Primary molded body 20a Tip portion 21 Lower projection (projection)
21c Exposed portion 30 Secondary molded body 34 Cylindrical wall portion 34a Inclined portion 38 Rib portion 40 Seal member

Claims (4)

A primary molded body in which a detection unit for detecting a change in magnetic flux to be detected is embedded in a tip portion, and a plurality of protrusions are formed from a side surface in a radially outward direction;
A secondary molded body obtained by resin insert molding the primary molded body in a state in which a part of the protrusion is exposed;
A cylindrical wall portion formed integrally with the secondary molded body in a region facing the radially outward direction with respect to at least a part of a portion where the protrusion is exposed;
An annular sealing member disposed along the outer peripheral surface of the cylindrical wall portion. The sensor of claim 1 on the outer peripheral surface of the cylindrical wall portion, the sealing groove where the sealing member is disposed is formed. The plurality of protrusions are formed at regular intervals along the outer periphery of the primary molded body at equal intervals,
3. The sensor according to claim 1, wherein the plurality of protrusions have tip surfaces that maintain contact with a mold during the resin insert molding. 4. A rib portion formed integrally with the secondary molded body,
The rib portion is formed by connecting the cylindrical wall portion and an outer surface of the secondary molded body between the plurality of protrusions and extending in an axial direction of the cylindrical wall portion. The sensor according to any one of 1 to 3 .

Images