Magnetic encoder, and method for manufacturing a magnetic encoder

Abstract

To provide a magnetic encoder capable of reliably retaining a performance for preventing mixture of moisture into a fitting portion between a cylindrical portion of a ring-shaped support member and an inner ring.SOLUTION: A cylindrical portion 4 of a ring-shaped support member 2 includes: a small-diameter portion 6 press-fitted into an inner ring of a bearing; and a large-diameter portion 7 formed by radially enlarging a portion in a side of an inboard IB than the small-diameter portion 6. A ring-shaped magnet member 3 has an inner-diameter-side recessed portion 8 in which an inner portion 3B in a radial direction R of a surface 3A in the side of the inboard IB is recessed to a side of an outboard OB, and has a routing portion 9 routed to the side of the outboard OB up to a step portion S between the small-diameter portion 6 and the large-diameter portion 7 of the cylindrical portion 4 so as to be along the ring-shaped support member 2. An inner peripheral surface 9A of the routing portion 9 press-fitted into the inner ring projects inward in the radiation direction R relative to an inner peripheral surface 6A of the small-diameter portion 6. A gate mark GM of an inner-diameter-side disk gate is located on an inner peripheral surface of the inner-diameter-side recessed portion 8.SELECTED DRAWING: Figure 4

Description

Technical Field

[0006]

[0001] The present invention relates to a magnetic encoder used for a wheel support bearing device of an automobile.

Background Art

[0002] A magnetic encoder device used for detecting the rotational speed (rotational frequency) of a rotating body includes a magnetic encoder and a magnetic sensor for detecting the rotation of the magnetic encoder. The magnetic encoder is attached to the rotating body, and the magnetic sensor is attached to a non-rotating body.

[0003] The magnetic encoder used for a wheel support bearing device (hub unit bearing) of an automobile is composed of an annular support member (slinger) and an annular magnet member. The magnetic sensor used for a wheel support bearing device of an automobile is attached to the outer ring of the bearing and faces the annular magnet member in the axial direction.

[0004] The annular support member is made of metal and includes a cylindrical portion that fits externally onto the inner ring of the bearing, and an outward flange portion that extends radially outward from one end of the cylindrical portion. The annular magnet member has N poles and S poles magnetized in multiple poles in the circumferential direction at a constant interval, and is attached to the outward flange portion of the annular support member.

[0005] In the wheel support bearing device, it is used in a state where the cylindrical portion of the annular support member is fitted onto the inner ring. Therefore, if moisture enters the fitting portion between the cylindrical portion and the inner ring, the outer peripheral surface of the iron-made inner ring will corrode.

[0006] In order to prevent moisture from entering the fitting portion, the inner peripheral surface of the cylindrical portion of the annular support member is made into a stepped cylindrical surface, and the annular magnet member is extended radially inward to abut against the step portion (for example, the step portion 27 in Patent Document 1) of the cylindrical portion, and the inner peripheral surface of the annular magnet member is made to have a tightening allowance with respect to the outer peripheral surface of the inner ring (for example, see Patent Documents 1 and 2).

[0007] In the magnetic encoder of Patent Document 1, the inner diameter (φd2) of the inner circumferential surface (cylindrical surface portion 28) of the annular magnet member is larger than the inner diameter (φd1) of the portion of the cylindrical part of the annular support member that fits onto the inner ring (small diameter portion 26), and smaller than the outer diameter (φD) of the inner ring (φd1 < φd2 < φD, see Figure 2 of Patent Document 1). In the magnetic encoder of Patent Document 2, the inner diameter of the inner circumferential surface (inner circumferential surface of the protruding portion 22) of the annular magnet member is smaller than the inner diameter of the portion of the cylindrical part of the annular support member that fits onto the inner ring (inner diameter of the inner circumferential surface 20e) (see the protruding length t1 in Figure 2 of Patent Document 2). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 6241188 [Patent Document 2] Japanese Patent Publication No. 2016-23755 [Overview of the project] [Problems that the invention aims to solve]

[0009] In the magnetic encoder structure of Patent Document 1, variations in the dimensional accuracy of the annular support member and the inner ring cause the engagement allowance between the portion of the cylindrical part of the annular support member that engages with the inner ring (small diameter portion 26) and the inner ring to fluctuate when the cylindrical portion of the annular support member is press-fitted into the inner ring. As a result, the contact state between the inner circumferential surface (cylindrical surface portion 28) of the annular magnet member and the outer circumferential surface of the inner ring fluctuates, and it is difficult to control the contact state to stay within a predetermined range. Therefore, in the magnetic encoder structure of Patent Document 1, depending on the contact state, the performance in preventing moisture from entering the engagement portion may decrease, potentially leading to moisture entering the engagement portion.

[0010] In contrast, in the structure of the magnetic encoder described in Patent Document 2, when the cylindrical portion of the annular support member is press-fitted into the inner ring, the inner diameter of the inner surface of the annular magnet member (the inner surface of the protruding portion 22) is smaller than the inner diameter of the portion of the cylindrical portion of the annular support member that fits into the inner ring (the inner diameter of the inner surface 20e). Therefore, the inner surface of the annular magnet member is reliably press-fitted into the inner ring. Consequently, the structure of the magnetic encoder described in Patent Document 2 is expected to have stable performance in preventing moisture from entering the fitting portion between the cylindrical portion of the annular support member and the inner ring.

[0011] The annular magnet member is manufactured by injection molding, and the inner circumferential surface of the annular magnet member (the inner circumferential surface of the protrusion 22) contacts the outer circumferential surface of the inner ring to prevent moisture from entering the fitting portion. Therefore, it is necessary to ensure that defects such as short shots do not occur in the resin forming the inner circumferential surface of the annular magnet member.

[0012] However, in the structure of the magnetic encoder described in Patent Document 2, when the magnet portion 21, which is the annular magnet member, is injection molded, the molten resin does not easily flow to the thin-walled protrusion 22 that extends to the stepped portion (position of boundary line D) of the cylindrical portion 20a of the annular support member, the slinger 20, making the aforementioned defects likely to occur. If the aforementioned defects occur on the inner surface of the annular magnet member that contacts the outer surface of the inner ring of the bearing, there is a risk that the performance of preventing moisture from entering the fitting portion between the cylindrical portion of the annular support member and the inner ring will not be maintained.

[0013] The present invention aims to provide a magnetic encoder that can reliably maintain the ability to prevent moisture from entering the fitting portion between the cylindrical portion of the annular support member and the inner ring, without causing defects such as short shots on the inner surface of the annular magnet member that contacts the outer surface of the inner ring of the bearing, and a method for manufacturing a magnetic encoder. [Means for solving the problem]

[0014] The magnetic encoder according to the present invention is a magnetic encoder used in a wheel support bearing device of an automobile, and comprises a metal annular support member and a plastic magnet annular magnet member. The annular support member comprises a cylindrical portion that fits onto the inner ring of the bearing of the wheel support bearing device, and an outward-facing flange portion that extends radially outward from the inboard end of the cylindrical portion. The cylindrical portion has a small diameter portion that is press-fitted into the inner ring of the bearing, and a large diameter portion formed by expanding the diameter of the portion on the inboard side of the small diameter portion. The annular magnet member is attached to the inboard side surface of the outward-facing flange portion. The annular magnet member has an inner diameter recess portion in which the radially inward portion of its inboard side surface is recessed toward the outboard side, and also has a wrap-around portion that curves toward the outboard side to the stepped portion between the small diameter portion and the large diameter portion of the cylindrical portion, so as to follow the annular support member. The inner circumferential surface of the wrap-around portion that is press-fitted into the inner ring protrudes radially inward more than the inner circumferential surface of the small diameter portion. The inner circumferential surface of the inner diameter recess has a gate mark from the inner diameter disk gate. Between the wrap-around portion and the gate mark, there is a part of the inner circumferential surface of the inner diameter recess, and the part of the inner circumferential surface of the inner diameter recess is cylindrical. ru.

[0015] The present invention relates to a method for manufacturing a magnetic encoder used in a wheel support bearing device for an automobile. The magnetic encoder comprises a metal annular support member and a plastic magnet annular magnet member. The annular support member comprises a cylindrical portion that fits onto the inner ring of the bearing of the wheel support bearing device, and an outward-facing flange portion that extends radially outward from the inboard end of the cylindrical portion. The cylindrical portion has a small diameter portion that is press-fitted onto the inner ring of the bearing, and a large diameter portion formed by expanding the diameter of the portion on the inboard side of the small diameter portion. The annular magnet member is attached to the inboard side surface of the outward-facing flange portion. The annular magnet member has an inner diameter recess portion in which the radially inner portion of its inboard side surface is recessed toward the outboard side, and also has a wrap-around portion that curves toward the outboard side to the stepped portion between the small diameter portion and the large diameter portion of the cylindrical portion, so as to follow the annular support member. The inner circumferential surface of the wrap-around portion that press-fits into the inner ring protrudes radially inward more than the inner circumferential surface of the small diameter portion. Between the gate mark formed on the inner circumferential surface of the inner diameter recess and the wrap-around portion, there is a part of the inner circumferential surface of the inner diameter recess, and the part of the inner circumferential surface of the inner diameter recess is cylindrical in shape.

[0016] The method for manufacturing the magnetic encoder is as follows: The aforementioned The process involves forming an annular support member by press working, or by press working and cutting; applying a thermosetting adhesive to part or all of the joint surface of the formed annular support member with the annular magnet member; opening the injection molding die and setting the annular support member to which the thermosetting adhesive has been applied as an insert work into the die; and closing the die and the inner diameter recess portion of the annular magnet member The gate mark Molten resin is injected into the cavity of the mold from the inner diameter side disk gate of the mold, which is positioned at the corresponding location. The aforementioned This includes the step of forming an annular magnet member. [Effects of the Invention]

[0017] According to the magnetic encoder of the present invention, the inboard side surface of the annular magnet member has an inner diameter recess in the radially inward portion, and the inner circumferential surface of the inner diameter recess has a gate mark of the inner diameter disk gate. Furthermore, between the wrap-around portion and the gate mark, there is a part of the inner circumferential surface of the inner diameter recess, and the part of the inner circumferential surface of the inner diameter recess is cylindrical in shape. The manufacturing method for a magnetic encoder according to the present invention involves an inner diameter side disk gate that injects molten resin into the cavity of an injection molding die when an annular magnet member is injection molded, and the inner diameter side recessed portion The gate mark It is placed in the corresponding position.

[0018] In other words, near the wrap-around portion of the annular magnet member that wraps around to the outboard side up to the stepped portion between the small-diameter and large-diameter portions of the cylindrical part of the annular support member. A position located at a distance from the aforementioned wrap-around portion by a portion of the inner circumferential surface of the inner diameter recess portion. The inner diameter side disk gate of the injection molding die is located there. As a result, molten resin flows easily from the inner diameter side disk gate to the thin-walled wrap-around portion, and the filling state of the molten resin in the wrap-around portion is stabilized, so that defects such as short shots do not occur on the inner circumferential surface of the wrap-around portion that contacts the outer circumferential surface of the inner ring of the bearing.

[0019] In the magnetic encoder according to the present invention and the magnetic encoder manufactured by the manufacturing method of the magnetic encoder according to the present invention, the inner peripheral surface of the recessed portion of the annular magnet member that is press-fitted into the inner ring of the bearing protrudes radially inward from the inner peripheral surface of the small-diameter portion of the cylindrical portion of the annular support member. Therefore, the recessed portion of the annular magnet member is surely press-fitted into the inner ring of the bearing. Moreover, no defects such as short shots occur on the inner peripheral surface of the recessed portion as described above. Therefore, the performance of preventing the intrusion of moisture into the fitting portion between the small-diameter portion of the cylindrical portion of the annular support member of the magnetic encoder and the inner ring of the bearing can be surely maintained.

Brief Description of the Drawings

[0020] [Figure 1] It is a longitudinal sectional view showing a wheel support bearing device for an automobile provided with a magnetic encoder according to an embodiment of the present invention. [Figure 2] It is an enlarged longitudinal sectional view of the main part around the magnetic encoder of FIG. 1. [Figure 3] It is a partial cross-sectional perspective view of the magnetic encoder. [Figure 4] It is a longitudinal sectional view of the magnetic encoder. [Figure 5] It is an enlarged cutaway end view of the main part of the magnetic encoder. [Figure 6] It is an enlarged view around the inner diameter side recessed portion in FIG. 5. [Figure 7] It is a sectional view of the annular support member. [Figure 8A] It is an enlarged cutaway end view of the main part of the annular support member, showing an example when a thermosetting adhesive is applied to a part of the bonding surface with the annular magnet member. [Figure 8B] It is an enlarged cutaway end view of the main part of the annular support member, showing the case when a thermosetting adhesive is applied to the entire bonding surface with the annular magnet member. [Figure 9] It is a schematic longitudinal sectional view of an injection mold, showing the state before injecting molten resin into the cavity. [Figure 10] It is a schematic longitudinal sectional view of an injection mold, showing the state after injecting molten resin into the cavity. [Figure 11] This is an enlarged view of the main part of Figure 10. [Figure 12] This is a longitudinal cross-sectional view of a modified magnetic encoder. [Figure 13] This is an enlarged cross-sectional end view of the main part of the modified example described above. [Figure 14] This is an enlarged view of the area around the inner diameter recess in Figure 13. [Figure 15] This is a schematic vertical cross-sectional view of a key part showing an example of an injection molding die for forming the annular magnet member of the above modified example, with molten resin injected into the cavity. [Modes for carrying out the invention]

[0021] Next, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0022] In this specification, with a magnetic encoder mounted on a bearing device for supporting the wheel of an automobile, the direction parallel to the rotation axis of the bearing device (see symbol O in Figure 1) is referred to as the "axial direction," and the direction perpendicular to the rotation axis is referred to as the "radial direction" (see arrow R in Figure 1). In the "radial direction," the direction away from the rotation axis is referred to as the "radial outward direction," and the direction approaching the rotation axis is referred to as the "radial inward direction." The "circumferential direction" is defined with respect to the direction of the rotation axis.

[0023] Furthermore, the direction from the vehicle body towards the wheels is called "outboard" (see arrow OB in Figure 1), and the direction from the vehicle wheels towards the vehicle body is called "inboard" (see arrow IB in Figure 1).

[0024] <Bearing device for supporting automobile wheels> As shown in the longitudinal cross-sectional view of Figure 1 and the enlarged longitudinal cross-sectional view of the main part of Figure 2, the wheel support bearing device A for an automobile equipped with a magnetic encoder 1 according to an embodiment of the present invention includes, in addition to the bearing B on which the inner ring 11, which serves as a wheel hub, rotates relative to the outer ring 12, an axial magnetic encoder 1, sealing members 10A and 10B arranged on the inboard IB side and outboard OB side of the bearing B, and a magnetic sensor MS, etc. The sealing members 10A and 10B prevent muddy water and the like from entering the bearing B and prevent leakage of lubricating grease.

[0025] Bearing B comprises an inner ring 11 with an inner ring raceway surface 11A formed on its outer circumference, an outer ring 12 with an outer ring raceway surface 12A formed on its inner circumference, and rolling elements 13, which are balls, that roll between the inner ring raceway surface 11A and the outer ring raceway surface 12A. The inner ring 11, the outer ring 12, and the rolling elements 13 are made of iron.

[0026] In the wheel support bearing device A of an automobile, the magnetic encoder 1 is located on the inboard IB side of the sealing member 10A (outside the sealed space of bearing B), and is therefore used in an environment exposed to the external atmosphere.

[0027] <Magnetic encoder> The magnetic encoder 1 shown in the longitudinal section of Figure 1, the enlarged longitudinal section of the main part of Figure 2, the partial cross-sectional perspective view of Figure 3, the longitudinal section of Figure 4, and the enlarged end view of the main part of Figure 5 consists of a metal annular support member 2 and a plastic magnet annular magnet member 3.

[0028] (Annular support member) The annular support member 2 consists of a cylindrical portion 4 that fits onto the inner ring 11 of the bearing B, and an outward-facing flange portion 5 that extends radially outward R from the inboard IB side end of the cylindrical portion 4. The cylindrical portion 4 has a small diameter portion 6 on the outboard OB side and a large diameter portion 7 formed by expanding the diameter of the portion on the inboard IB side of the small diameter portion 6. The small diameter portion 6 is press-fitted onto the inner ring 11 (see fitting portion F in Figure 2), so the inner circumferential surface 6A of the small diameter portion 6 contacts the outer circumferential surface 11B of the inner ring 11. The diameter of the inner circumferential surface 6A of the small diameter portion 6 is, for example, 40 mm to 100 mm.

[0029] The annular support member 2 is formed, for example, from a stainless steel plate with a thickness of 0.6 mm by press working.

[0030] (Annular magnet component) The annular magnet member 3 is attached to the inboard IB side surface 5A of the outward-facing flange portion 5 of the annular support member 2. The annular magnet member 3 is multi-pole magnetized in the circumferential direction with N and S poles at regular intervals, and is formed from a magnetic material containing, for example, magnetic powder, a binder, and additives.

[0031] Suitable magnetic powders include ferrite-based magnetic powders such as strontium ferrite and barium ferrite, as well as rare-earth magnetic powders such as neodymium and samarium. Suitable binders include thermoplastic resin materials such as polyamide (PA6, PA12, PA612, etc.) and polyphenylene sulfide (PPS). Suitable additives include organic additives such as carbon fiber, and inorganic additives such as glass beads, glass fibers, talc, mica, silicon nitride (ceramic), and crystalline (amorphous) silica.

[0032] The annular magnet member 3 has an inner diameter recess 8 on its inboard side surface 3A, where the radially inward portion 3B is recessed toward the outboard side OB. The annular magnet member 3 has a wrap-around portion 9 that curves around toward the outboard side OB to the stepped portion S between the small diameter portion 6 and the large diameter portion 7 of the cylindrical portion 4, so as to follow the annular support member 2. The inner circumferential surface 9A of the wrap-around portion 9, which is press-fitted into the inner ring 11 of the bearing B, protrudes radially inward R than the inner circumferential surface 6A of the small diameter portion 6 of the cylindrical portion 4.

[0033] The annular magnet member 3 is molded attached to the annular support member 2 by insert molding. Specifically, the annular magnet member 3 is molded by injection molding using the annular support member 2, to which a thermosetting adhesive Q (see Figures 8A and 8B) has been applied to the bonding surface W with the annular magnet member 3, as the insert work.

[0034] As shown in the longitudinal cross-sectional view of Figure 4 and the enlarged end view of the main part of Figure 5, the inner circumferential surface 8A of the inner diameter recess 8 of the annular magnet member 3 is cylindrical. As shown in Figures 3 to 5, the inner circumferential surface 8A of the inner diameter recess 8 has a gate mark GM of the inner diameter disk gate G (see Figures 9 to 11).

[0035] (Dimensional range around the inner diameter recess) In the embodiment shown in the end view of the enlarged section of the main part in Figure 6, the length H of the radial R of the inner diameter recess 8 is preferably 0.05 mm ≤ H ≤ 2 mm. If H < 0.05 mm, when the magnetic encoder 1 is assembled into the inner ring 11 of the bearing B, the gate mark GM may come into contact with the inner ring 11, potentially causing contamination. If H > 2 mm, the distance between the inner diameter disc gate G located on the inner circumferential surface 8A of the inner diameter recess 8 and the wrap-around portion 9 becomes greater, making it difficult for molten resin to flow into the wrap-around portion 9 when the annular magnet member 3 is molded by injection molding.

[0036] In the embodiment shown in Figure 6, the axial length I of the inner diameter recess 8 is preferably I ≥ 0.2 mm. If I < 0.2 mm, it becomes difficult to position the inner diameter disk gate G.

[0037] In a preferred embodiment, the axial distance U between the outboard OB side end 8B of the inner circumferential surface 8A of the inner diameter recess 8 shown in Figure 6 and the inboard IB side surface 5A of the outward flange 5 of the annular support member 2 is U ≥ 0.1 mm. If U < 0.1 mm, the flow path to the wrap-around portion 9 becomes narrower when the annular magnet member 3 is molded by injection molding, making it difficult for molten resin to flow into the wrap-around portion 9.

[0038] The axial length I and axial distance U shown in Figure 6 are given by I + U = T, where T is the thickness of the annular magnet member 3. If the thickness T of the annular magnet member 3 is determined, then under the conditions I ≥ 0.2 mm and U ≥ 0.1 mm, if one of I and U is determined, the other is determined.

[0039] (Dimensional range around the wrap-around part) In a preferred embodiment, the axial length J of the inner peripheral surface 9A of the recessed portion 9 shown in FIG. 6 is set such that 0.2 mm ≤ J ≤ 1.5 mm. When J < 0.2 mm, the performance of preventing moisture from entering the fitting portion F (FIG. 2) may deteriorate. When J > 1.5 mm, since the thin-walled recessed portion 9 becomes longer, it becomes difficult for the molten resin to flow into the recessed portion 9 when molding the annular magnet member 3 by injection molding.

[0040] In a preferred embodiment, the protrusion amount K of the inner peripheral surface 9A from the inner peripheral surface 6A shown in FIG. 6 is set such that 0 < K ≤ 0.1 mm. When K ≤ 0 (when the inner peripheral surface 9A does not protrude from the inner peripheral surface 6A, that is, when the inner peripheral surface 9A is flush with the inner peripheral surface 6A or the inner diameter of the inner peripheral surface 9A is larger than that of the inner peripheral surface 6A), the performance of preventing moisture from entering the fitting portion F (FIG. 2) may deteriorate. When K > 0.1 mm, the annular magnet member 3 may be damaged when the magnetic encoder 1 is incorporated into the inner ring ll.

[0041] In a preferred embodiment, the thickness L of the recessed portion 9 shown in FIG. 6 is set such that 0.1 mm ≤ L ≤ 0.4 mm. When L < 0.1 mm, it becomes difficult for the molten resin to flow into the recessed portion 9 when molding the annular magnet member 3 by injection molding. When L > 0.4 mm, the thickness of the large-diameter portion 7 of the annular support member 2 becomes thin, resulting in a decrease in strength and rigidity, and the annular support member 2 may be deformed when the magnetic encoder 1 is incorporated into the inner ring 11.

[0042] <Method for manufacturing magnetic encoder> (Annular support member forming step) The annular support member 2 having the shape shown in FIG. 7 is formed by pressing or pressing and cutting.

[0043] For example, a circular plate material is obtained by punching a flat plate material made of stainless steel. Next, the circular plate material is subjected to flanging to form the annular support member 2 having the large-diameter portion 7. Alternatively, after the flanging is performed, the large-diameter portion 7 is provided by cutting.

[0044] (Adhesive application step) Next, a thermosetting adhesive Q is applied to a predetermined area of ​​the annular support member 2, for example, the area shown in the enlarged cross-section end view of the main part in Figure 8A, or the enlarged cross-section end view of the main part in Figure 8B. Examples of thermosetting adhesive Q include phenolic resin adhesives and epoxy resin adhesives. In Figures 8A and 8B, the thickness of the adhesive Q is shown exaggeratedly compared to its actual thickness.

[0045] Specifically, as shown in the enlarged cross-section end view of the main part in Figure 8A, a thermosetting adhesive Q is applied to a portion of the joint surface W between the molded annular support member 2 and the annular magnet member 3. Alternatively, as shown in the enlarged cross-section end view of the main part in Figure 8B, a thermosetting adhesive Q is applied to the entire joint surface W between the molded annular support member 2 and the annular magnet member 3.

[0046] For example, by applying adhesive Q to the area from the inner circumferential surface of the large-diameter portion 7 to the stepped portion S, as shown in Figure 8B, the propagation of cracks in the resin of the wrap-around portion 9 (see Figure 4) after the annular magnet member 3 has been formed by injection molding can be slowed, thereby improving the thermal shock resistance of the magnetic encoder 1.

[0047] (Annular support member setting process) Next, the injection molding die D shown in the schematic longitudinal cross-sectional view of Figure 9 is opened, and the annular support member 2, to which the thermosetting adhesive Q has been applied, is set inside the die D as an insert workpiece.

[0048] In other words, in the schematic longitudinal cross-sectional view of Figure 9, the movable core 15 is opened relative to the fixed core 14, and with the center core 16 removed, the annular support member 2 is set on the movable core 15 and the center core 16 is attached.

[0049] (Annular magnet component molding process) Next, the annular magnet member 3 is formed by injection molding.

[0050] That is, as shown in the schematic longitudinal section view of Figure 9, the movable core 15 is closed against the fixed core 14 to clamp the mold. Next, as shown in the schematic longitudinal section view of Figure 10, molten resin P is injected from the sprue 17. The molten resin P passes through the runner 18 and is injected into the cavity C of the mold D from the inner diameter side disk gate G of the mold D, which is positioned at a location corresponding to the inner circumferential surface 8A (see Figure 5) of the inner diameter side recess 8 of the annular magnet member 3, as shown in the enlarged view of the main part of Figure 11. As a result, the cavity C is filled with molten resin P.

[0051] (Molded product removal process) After the molten resin P has cooled and solidified, the movable core 15 is opened from the parting line PL shown in Figures 10 and 11. Next, the molded product and the center core 16, before gate cutting, are removed by ejecting them with an ejector pin (not shown). Then, the gate cutting process is performed to separate the insert molded product, the magnetic encoder 1, from the gate portion. As shown in Figures 3 to 5, the magnetic encoder 1 has a gate mark GM of the inner diameter side disk gate G on the inner circumferential surface 8A of the inner diameter side recess 8.

[0052] (Magnetization process) The annular magnet member 3 is magnetized in multiple poles in the circumferential direction. This magnetization is achieved, for example, by injecting the annular magnet member in a controlled magnetic field during the molding process, thereby orienting the magnetic powder in the magnetic field. Alternatively, after demagnetizing the magnetic encoder 1 obtained in the molded product removal process, the annular magnet member 3 is magnetized in multiple poles such as alternating north and south poles in the circumferential direction using a magnetization device such as a separately prepared magnetization yoke.

[0053] <Variation> In the above embodiments, the inner circumferential surface 8A of the inner diameter recess 8 of the annular magnet member 3 is cylindrical, as shown, for example, in the enlarged cross-sectional end view of the main part in Figure 5. However, the inner circumferential surface 8A of the inner diameter recess 8 is not limited to being cylindrical.

[0054] The inner circumferential surface 8A of the inner diameter recess 8 may include an inclined surface E as shown in the longitudinal cross-sectional view of Figure 12 and the end view of the enlarged section of the main part of Figure 13. The inclined surface E has a frustoconical side shape that approaches outward in the radial direction R as it goes toward the inboard IB side, and there is a gate mark GM on the inclined surface E.

[0055] (Dimensional range around the inner diameter recess) In the end view of the enlarged section of the main part shown in Figure 14, it is preferable that the radial distance V1 between the inner circumferential surface 9A of the wrap-around portion 9 and the inner end N1 of the inclined surface E in the radial direction R be V1 ≥ 0.05 mm. If V1 < 0.05 mm, the gate mark GM may come into contact with the inner ring 11 when the magnetic encoder 1 is assembled into the inner ring 11 of the bearing B, potentially causing contamination.

[0056] In the embodiment shown in Figure 14, the radial distance V2 between the inner circumferential surface 9A of the wrap-around portion 9 and the outer end N2 of the inclined surface E in the radial direction R is preferably set to V2 ≤ 2 mm. If V2 > 2 mm, the inner diameter side disk gate G located on the inclined surface E of the inner diameter side recess 8A and the wrap-around portion 9 become farther apart, making it difficult for molten resin to flow into the wrap-around portion 9 when molding the annular magnet member 3 by injection molding.

[0057] In the embodiment shown in Figure 14, the axial length I of the inner diameter recess 8 and the axial distance U between the outboard OB side end 8B of the inner circumferential surface 8A of the inner diameter recess 8 and the inboard IB side surface 5A of the outward flange portion 5 of the annular support member 2 are preferably set to I≧0.2mm and U≧0.1mm, similar to the axial length I and axial distance U in Figure 6.

[0058] (Dimensional range around the wrap-around part) The axial length J of the inner peripheral surface 9A of the recessed portion 9 shown in FIG. 14 is preferably set to 0.2 mm ≤ J ≤ 1.5 mm from the same viewpoint as the axial length J in FIG. 6. The protruding amount K of the inner peripheral surface 9A from the inner peripheral surface 6A shown in FIG. 14 is preferably set to 0 < K ≤ 0.1 mm from the same viewpoint as the protruding amount K in FIG. 6. The thickness L of the recessed portion 9 shown in FIG. 14 is preferably set to 0.1 mm ≤ L ≤ 0.4 mm from the same viewpoint as the thickness L in FIG. 6.

[0059] (Example of injection mold for injection molding) An example of an injection mold D for molding the annular magnet member 3 of the magnetic encoder 1 shown in the longitudinal sectional view of FIG. 12 is shown in a main part enlarged schematic longitudinal sectional view of FIG. 15. In the annular magnet member molding step, the inner diameter side disk gate G of the injection mold D for molding the annular magnet member 3 by injection molding is arranged at a position corresponding to the inclined surface E (see FIG. 13) of the inner peripheral surface 8A of the inner diameter side recessed portion 8 of the annular magnet member 3 as shown in FIG. 15.

[0060] <Operational effects> According to the magnetic encoder 1 according to the embodiment of the present invention, there is an inner diameter side recessed portion 8 in the inner portion 3B in the radial direction R of the surface 3A on the inboard IB side of the annular magnet member 3, and there is a gate mark GM of the inner diameter side disk gate G on the inner peripheral surface 8A of the inner diameter side recessed portion 8. According to the manufacturing method of the magnetic encoder 1 according to the embodiment of the present invention, the inner diameter side disk gate G for injecting the molten resin P into the cavity C of the injection mold D when injecting and molding the annular magnet member 3 is arranged at a position corresponding to the inner peripheral surface 8A of the inner diameter side recessed portion 8.

[0061] That is, the inner diameter side disk gate G of the injection mold D is located near the recessed portion 9 of the annular magnet member 3 that wraps around to the outboard OB side up to the step portion S between the small diameter portion 6 and the large diameter portion 7 of the cylindrical portion 4 of the annular support member 2. Thereby, the molten resin P easily flows from the inner diameter side disk gate G to the thin-walled recessed portion 9, and the filling state of the molten resin P in the recessed portion 9 is stabilized, so that defects such as short shots do not occur on the inner peripheral surface 9A of the recessed portion 9 that contacts the outer peripheral surface 11B of the inner ring 11 of the bearing B.

[0062] In the magnetic encoder 1 according to the present invention, and in the magnetic encoder 1 manufactured by the method for manufacturing the magnetic encoder according to the present invention, the inner circumferential surface 9A of the wrap-around portion 9 of the annular magnet member 3, which is press-fitted into the inner ring 11 of the bearing B, protrudes radially inward in the direction R than the inner circumferential surface 6A of the small diameter portion 6 of the cylindrical portion 4 of the annular support member 2. Therefore, the wrap-around portion 9 of the annular magnet member 3 is reliably press-fitted into the inner ring 11 of the bearing B. Furthermore, as described above, no defects such as short shots occur on the inner circumferential surface 9A of the wrap-around portion 9. Therefore, the ability to reliably prevent moisture from entering the fitting portion F between the small diameter portion 6 of the cylindrical portion 4 of the annular support member 2 of the magnetic encoder 1 and the inner ring 11 of the bearing B can be reliably maintained.

[0063] The embodiments described above are all illustrative and not limiting. Various improvements and modifications can be made without departing from the scope of the present invention. [Explanation of Symbols]

[0064] 1. Magnetic encoder 2. Annular support member 3. Annular magnet member 3A: Inboard side 3B Radial inner portion 4 Cylindrical portion 5 Outward-facing flange portion 5A Inboard side 6 Small diameter section 6A inner circumferential surface 7. Large diameter section 8. Inner diameter recessed section 8A Inner surface 8B Outboard side edge 9 Wrap-around section 9A Inner circumferential surface 10A, 10B sealing member 11 inner ring 11A Inner raceway surface 11B Outer surface 12 Outer ring 12A Outer ring raceway surface 13 Rolling element 14 Fixed core 15 Movable core 16 Center core 17 Spruce 18 Runners A. Bearing device for supporting automobile wheels B. Bearing C Cavity D Injection molding die E Inclined surface F Fitting part G Inner diameter side disc gate GM Gate mark H: Length in the radial direction I: Length in the axial direction IB Inboard J Axial Length K: Projection amount L: Thickness M S Magnetic Sensor N1: Inner end in the radial direction N2: Outer end in the radial direction O Rotation axis OB Outboard P Molten resin PL Harding line Q Thermosetting adhesive R Radial direction S-section T-thickness U-axis distance V1, V2 radial distance W joint surface

Claims

1. A magnetic encoder used in a bearing device for supporting the wheels of an automobile, It consists of a metal annular support member and a plastic magnet annular magnet member. The aforementioned annular support member is A cylindrical portion that fits onto the inner ring of the bearing of the wheel support bearing device, An outward-facing flange portion extending radially outward from the inboard end of the cylindrical portion, It consists of, The cylindrical portion has a small diameter portion that is press-fitted into the inner ring of the bearing, and a large diameter portion formed by expanding the diameter of the portion on the inboard side of the small diameter portion. The annular magnet member is attached to the inboard side surface of the outward-facing flange portion. The annular magnet member has an inner diameter recess portion in which the radially inner portion of its inboard side surface is recessed toward the outboard side, and also has a wrap-around portion that curves toward the outboard side up to the stepped portion between the small diameter portion and the large diameter portion of the cylindrical part, so as to follow the annular support member. The inner circumferential surface of the wrap-around portion that press-fits into the inner ring protrudes radially inward more than the inner circumferential surface of the small diameter portion. On the inner circumferential surface of the inner diameter recess, there is a gate mark of the inner diameter disk gate. Between the aforementioned wrap-around portion and the gate mark, there is a part of the inner circumferential surface of the inner diameter side recess, A portion of the inner circumferential surface of the inner diameter recess is cylindrical. Magnetic encoder.

2. A method for manufacturing a magnetic encoder used in a bearing device for supporting the wheels of an automobile, The magnetic encoder consists of a metal annular support member and a plastic magnet annular magnet member. The aforementioned annular support member is A cylindrical portion that fits onto the inner ring of the bearing of the wheel support bearing device, An outward-facing flange portion extending radially outward from the inboard end of the cylindrical portion, It consists of, The cylindrical portion has a small diameter portion that is press-fitted into the inner ring of the bearing, and a large diameter portion formed by expanding the diameter of the portion on the inboard side of the small diameter portion. The annular magnet member is attached to the inboard side surface of the outward-facing flange portion. The annular magnet member has an inner diameter recess portion in which the radially inner portion of its inboard side surface is recessed toward the outboard side, and also has a wrap-around portion that curves toward the outboard side up to the stepped portion between the small diameter portion and the large diameter portion of the cylindrical part, so as to follow the annular support member. The inner circumferential surface of the wrap-around portion that press-fits into the inner ring protrudes radially inward more than the inner circumferential surface of the small diameter portion. Between the aforementioned wrap-around portion and the gate mark formed on the inner circumferential surface of the inner diameter side recess, there is a part of the inner circumferential surface of the inner diameter side recess. A portion of the inner circumferential surface of the inner diameter recess is cylindrical, A step of forming the annular support member by press working, or by press working and cutting, A step of applying a thermosetting adhesive to a part or all of the bonding surface between the molded annular support member and the annular magnet member, The process involves opening the injection molding die and setting the annular support member, to which the thermosetting adhesive has been applied, as an insert workpiece inside the die. The process involves closing the mold and injecting molten resin into the cavity of the mold from the inner diameter side disk gate of the mold, which is positioned at a location corresponding to the gate mark in the inner diameter side recess of the annular magnet member, thereby forming the annular magnet member. including, A method for manufacturing a magnetic encoder.

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