Toothed pulley

Abstract

To prevent, in a toothed pulley including a cylindrical metallic core and a resin portion with teeth, the metallic core and the resin portion from relatively rotating in the circumferential direction while securing the accuracy in teeth and preventing the manufacturing cost from increasing.SOLUTION: A toothed pulley A includes a cylindrical metallic core B and a resin portion C including teeth T. The metallic core B has, at one end thereof in the axial direction, an outward flange D projecting outward in the radial direction. The outward flange D has a radially outer peripheral surface M that is a rotation prevention shape F having a plurality of parts displaced inward in the radial direction from a cylindrical surface thereof. The radially outer peripheral surface M of the outward flange D is covered by the resin portion C.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a toothed pulley that meshes with a toothed belt. [Background technology]

[0002] 2. Description of the Related Art As a power transmission mechanism for an electric power steering device, a belt transmission mechanism consisting of a drive-side toothed pulley, a driven-side toothed pulley, and a toothed belt is used (see, for example, belt transmission mechanism 30 in Patent Document 1).

[0003] The material of the toothed pulley is usually steel in order to meet the required specifications of strength and precision, but there are also pulleys with synthetic resin teeth combined with a cylindrical core metal (hub base 2) to reduce weight (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-44854 A [Patent Document 2] DE 102006059946 [Patent Document 3] JP 2008-163967 A [Patent Document 4] Japanese Utility Model Publication No. 61-40983 Summary of the Invention [Problem to be solved by the invention]

[0005] When a toothed pulley is formed by a cylindrical core and a resin portion including teeth, it is necessary to prevent the core and the resin portion from rotating in the circumferential direction.

[0006] As an example of such a circumferential rotation prevention, there is a pulley-equipped bearing device 106 in which a resin pulley body 22 is insert-molded into a metal mounting member 21 that is press-fitted into the outer ring 11 of the bearing 10 (see, for example, Patent Document 3). The pulley-equipped bearing device 106 is an idler pulley that presses against the back surface of the toothed belt 105, and is not a toothed pulley.

[0007] In the pulley-equipped bearing device 106 of Patent Document 3, rectangular openings 21c are formed in the outer periphery of a hollow cylindrical portion 21a of a metal mounting member 21, arranged at equal intervals in the circumferential direction. Then, a resin pulley body 22 is insert-molded on the radially outer side of the metal mounting member 21, with the metal mounting member 21 as an insert part. As a result, molten resin enters the openings 21c and solidifies, thereby preventing rotation in the circumferential direction and preventing slipping out in the axial direction.

[0008] If the structure of Patent Document 3 is used in a toothed pulley that requires high tooth accuracy, the radial thickness of the resin pulley body 22 will be large, which will increase the difference in thickness from the total tooth height and the shrinkage difference, making it impossible to meet the required specifications for tooth accuracy. In addition, the metal mounting member 21 will need to be thickened, which will increase its weight. Furthermore, molten resin will enter the opening 21c, causing burrs to form on the inner diameter side of the metal mounting member 21, and when the rectangular openings 21c arranged in the circumferential direction of the metal mounting member 21 are press-molded, burrs will form on the inner diameter side of the metal mounting member 21, making it necessary to perform a process of removing the burrs.

[0009] Another example of preventing circumferential rotation is a synthetic resin ring 4 that is insert-molded into a metal ring member 8 that is press-fitted into an outer ring 3 of a bearing 2 in a rotating ring 1 (see, for example, Patent Document 4). The rotating ring 1 is a load pulley and is not a toothed pulley.

[0010] In the rotating wheel 1 of Patent Document 4, an eccentric flange 7 that protrudes radially outward is provided at the axial end of a metal ring member 8. Then, a synthetic resin ring body 4 is insert-molded on the radial outside of the metal ring member 8, using the metal ring member 8 as an insert part. As a result, the molten resin solidifies to cover the eccentric flange 7, thereby preventing rotation in the circumferential direction and preventing it from coming off in the axial direction.

[0011] If the structure of Patent Document 4 is used in a toothed pulley that requires high tooth accuracy, the radial thickness of the synthetic resin ring body 4 will be large, which will increase the difference in thickness from the total tooth depth and also increase the shrinkage difference, making it impossible to meet the required specifications for tooth accuracy.

[0012] As a method for preventing rotation in the circumferential direction between the cylindrical core and the resin part including teeth, it is possible to form a knurled portion, for example a twill pattern, on the outer circumferential surface of the core by knurling the outer circumferential surface of the core. By performing insert injection molding using the core as an insert, the synthetic resin will enter the knurled portion, thereby preventing rotation in the circumferential direction.

[0013] The knurling process for the core bar requires a step of forming the knurled portion on the outer circumferential surface of the core bar by pressing a knurling tool against the core bar while rotating the core bar on a lathe, etc. Therefore, the processing cost of the knurling process is high, and the manufacturing cost of the toothed pulley increases.

[0014] The present invention aims to provide a toothed pulley composed of a cylindrical core and a resin part including teeth, which requires high tooth precision, by preventing circumferential rotation of the core and the resin part while ensuring tooth precision and not increasing manufacturing costs. [Means for solving the problem]

[0015] The present invention First viewpoint The toothed pulley according to 、 A toothed pulley that is required to have high tooth precision and is made of a cylindrical core metal and a resin portion including teeth, The core metal has an outward flange protruding radially outward at an axial end thereof, The radial outer circumferential surface of the outward flange has a shape including a plurality of portions displaced radially inward from a cylindrical surface, The outward flange The core metal The radial outer peripheral surface of the 、 The radial inner peripheral surface of the core metal is exposed, The core metal has a bottom plate at one end in the axial direction, The bottom plate of the core metal has a plurality of axial mounting holes and a plurality of holes into which the resin portion is inserted, The resin portion has a bottom plate at one end in the axial direction, The bottom plate of the resin portion has a notch for exposing the mounting hole of the bottom plate of the core metal in the axial direction. do.

[0016] According to this configuration, the toothed pulley can be made lighter because the toothed pulley is made of a resin part. The radial outer peripheral surface of the outward flange of the core has a shape including a plurality of parts that are displaced radially inward from a cylindrical surface, and the radial outer peripheral surface of the outward flange is covered with a resin part. Therefore, the core and the resin part can be prevented from rotating in the circumferential direction.

[0017] Moreover, the shape of the radial outer circumferential surface of the core bar's outward flange, i.e., the shape including a plurality of portions displaced radially inward from the cylindrical surface, can be formed by pressing, and therefore there is no need for post-processing such as knurling after pressing, and therefore no increase in manufacturing costs.

[0018] Furthermore, since the radial outer peripheral surface of the outward flange of the core bar has a shape including a plurality of portions displaced radially inward from the cylindrical surface, the radial outward protrusion length of the outward flange can be reduced. Therefore, since the radial thickness of the resin portion does not increase, the difference in thickness with respect to the total tooth depth is reduced, and the shrinkage difference is also reduced, making it easier to satisfy the required specifications for the tooth accuracy of the toothed pulley, which requires high tooth accuracy.

[0019] In addition, the core has a bottom plate at one axial end, and the bottom plate of the core has a plurality of axial mounting holes and a plurality of draw holes into which the resin portion fits, so that the toothed pulley can be easily and reliably fixed to the member to which it is attached by means of bolts passed through the mounting holes of the core. In addition, the draw holes make the core lighter, and the resin portion fits into the draw holes of the core, so that the core also has the function of preventing the resin portion including the teeth and the core from rotating in the circumferential direction.

[0020] Moreover, the resin part has a bottom plate at one axial end, and the bottom plate of the resin part has a notch that exposes the mounting hole of the bottom plate of the core bar in the axial direction, so that the strength and rigidity of the resin part are increased by the bottom plate provided in the resin part. Moreover, since the notch is provided in the bottom plate of the resin part, the mounting hole of the bottom plate of the core bar is exposed in the axial direction, so that the bottom plate of the resin part does not get in the way when attaching the toothed pulley to a member to which the toothed pulley is to be attached.

[0021] A toothed pulley according to a second aspect of the present invention comprises: A toothed pulley that is required to have high tooth precision and is made of a cylindrical core metal and a resin portion including teeth, The core metal has an outward flange protruding radially outward at an axial end thereof, The radial outer circumferential surface of the outward flange has a shape including a plurality of portions displaced radially inward from a cylindrical surface, a radial outer circumferential surface of the outward flange is covered with the resin portion, The core metal is A first core bar; a second core bar that is concentric with the first core bar and is located radially outward from the first core bar so as to have a radial gap therebetween; It consists of: the first core bar has the outward flange at an axial end thereof, The resin portion is It is a thermoplastic resin, The resin in the gap between the first core bar and the second core bar and the resin in the teeth are included in the same part. 。

[0022] According to this configuration, the shape of the radial outer peripheral surface of the outward flange of the first core bar prevents the first core bar forming the inner diameter of the toothed pulley from rotating in the circumferential direction with the resin part. Furthermore, since the cylindrical core bar of the toothed pulley is the first core bar and the second core bar, the core bar can be made thinner, and the toothed pulley can be made lighter. Furthermore, since the resin part is made of a thermoplastic resin, the productivity of the toothed pulley is increased.

[0023] In addition, the cylindrical core is composed of a first core that forms the inner diameter of the toothed pulley and a second core that is located radially outward from the first core, and therefore the thickness of the resin portion located radially outward from the first core can be appropriately set by the second core, making it easier to satisfy the required specifications for the accuracy of the teeth of the toothed pulley.

[0024] A toothed pulley according to a third aspect of the present invention is the toothed pulley according to the second aspect, the second core bar has an outward flange protruding radially outward or an inward flange protruding radially inward at one end or the other end in the axial direction, The radial outer circumferential surface of the outward flange has a shape including a plurality of portions displaced radially inward from a cylindrical surface, The radially inner peripheral surface of the inward flange has a shape including a plurality of portions displaced radially outward from a cylindrical surface, The radial outer peripheral surface of the outward flange or the radial inner peripheral surface of the inward flange is covered with the resin portion. 。

[0025] With this configuration, the above-mentioned shape of the radial outer peripheral surface of the outward flange of the second core bar or the above-mentioned shape of the radial inner peripheral surface of the inward flange can prevent circumferential rotation between the second core bar and the resin portion.

[0026] Moreover, the shape of the radial outer peripheral surface of the outward flange of the second core bar or the shape of the radial inner peripheral surface of the inward flange of the second core bar can be formed by pressing, which eliminates the need for post-processing such as knurling after pressing, and thus does not increase manufacturing costs.

[0027] Furthermore, since the shape of the radially outer peripheral surface of the outward flange of the second core bar includes a plurality of portions displaced radially inward from the cylindrical surface, the radially outward protruding length of the outward flange can be reduced. Alternatively, since the shape of the radially inner peripheral surface of the inward flange of the second core bar includes a plurality of portions displaced radially outward from the cylindrical surface, the radially inward protruding length of the inward flange can be reduced. Therefore, since the radial thickness of the resin portion does not increase, the difference in thickness from the total tooth depth is reduced, and the shrinkage difference is also reduced, making it easier to satisfy the required specifications for the accuracy of the teeth of the toothed pulley.

[0028] A toothed pulley according to a fourth aspect of the present invention is the toothed pulley according to the second or third aspect, The first core bar has a bottom plate at one end in the axial direction, The bottom plate has a plurality of axial mounting holes and a plurality of holes into which the resin portion is inserted.。

[0029] With this configuration, the toothed pulley can be easily and reliably fixed to the member to which it is attached by means of a bolt passed through the mounting hole in the first core. In addition, the first core can be made lighter by the hole, and the resin portion fits into the hole in the first core, which also serves to prevent the resin portion including the teeth and the first core from rotating in the circumferential direction.

[0030] A toothed pulley according to a fifth aspect of the present invention is the toothed pulley according to the fourth aspect, The resin portion has a bottom plate at one end in the axial direction, The bottom plate of the resin portion has a notch for exposing the mounting hole of the bottom plate of the first core bar in the axial direction. 。

[0031] According to this configuration, the strength and rigidity of the resin part is increased by the bottom plate provided in the resin part. Moreover, since the mounting hole of the bottom plate of the first core bar is exposed in the axial direction by providing a notch in the bottom plate of the resin part, the bottom plate of the resin part does not get in the way when attaching the toothed pulley to the member to which the toothed pulley is to be attached.

[0032] A toothed pulley according to a sixth aspect of the present invention is the toothed pulley according to any one of the first to fifth aspects, The resin portion is At one axial end, an outward flange is provided which protrudes radially outward beyond the tips of the teeth. 。

[0033] According to this configuration, the outward flange can restrict axial movement of the toothed belt meshing with the toothed pulley. Effect of the Invention

[0034] According to the toothed pulley of the present invention described above, in a toothed pulley consisting of a cylindrical core and a resin part including teeth, which requires high tooth precision, it is possible to prevent circumferential rotation of the core and the resin part without increasing manufacturing costs while ensuring tooth precision. [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a perspective view of a toothed pulley according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a partial cross-sectional perspective view of the toothed pulley of FIG. 1; [Figure 3A] FIG. 2 is a longitudinal sectional view of the toothed pulley of FIG. [Figure 3B] FIG. 3B is an enlarged view of a main portion of the toothed pulley of FIG. 3A. [Figure 4] FIG. 2 is an exploded perspective view of a first core bar and a second core bar. [Figure 5A] FIG. 4 is a view of the first core bar as seen from the axial direction. [Figure 5B] 13 is an enlarged explanatory view of a main portion of the anti-rotation shape of the outward flange of the first core bar. FIG. [Figure 6A] FIG. 13 is a perspective view of a modified example of the first core bar. [Figure 6B] FIG. 13 is a perspective view of another modified example of the first core bar. [Figure 7] FIG. 11 is a perspective view of a toothed pulley according to a second embodiment of the present invention. [Figure 8] FIG. 8 is a partial cross-sectional perspective view of the toothed pulley of FIG. 7. [Figure 9A] FIG. 8 is a longitudinal sectional view of the toothed pulley of FIG. [Figure 9B] FIG. 9B is an enlarged view of a main part of the toothed pulley of FIG. 9A. [Figure 10] FIG. [Figure 11A] FIG. [Figure 11B] 13 is an enlarged explanatory view of a main portion of the anti-rotation shape of the outward flange of the core bar. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0037] The toothed pulley according to the embodiment of the present invention is used in a power transmission mechanism of an electric power steering device, and therefore high precision is required for the toothed pulley according to the embodiment of the present invention.

[0038] In this specification, the direction perpendicular to the direction of the rotation axis of the toothed pulley (see symbol O in Figures 3A and 5A, and Figures 9A and 11A) is called the "radial direction" (see arrow H in Figures 3A and 5A, and Figures 9A and 11A), the direction parallel to the direction of the rotation axis is called the "axial direction" (see arrow J in Figures 3A and 9A), and the horizontal direction perpendicular to the "radial direction" when the direction of the rotation axis is vertical is called the "circumferential direction" (see arrow I in Figures 5B and 11B).

[0039] [Embodiment 1]

[0040] <Toothed pulley> As shown in the perspective view of Fig. 1, the partial sectional perspective view of Fig. 2, the longitudinal sectional view of Fig. 3A, and the enlarged longitudinal sectional view of a main portion of Fig. 3B, a toothed pulley A according to a first embodiment of the present invention is composed of a cylindrical core B and a resin part C including teeth T. Since the part including the teeth T of the toothed pulley A is made of the resin part C, the weight of the toothed pulley A can be reduced. The teeth T of the toothed pulley A mesh with the teeth of a toothed belt (not shown). The teeth T of the toothed pulley A according to this embodiment are helical.

[0041] <Core> As shown in the partial cross-sectional perspective view of Fig. 2, the vertical cross-sectional view of Fig. 3A, the enlarged vertical cross-sectional view of a main part of Fig. 3B, and the exploded perspective view of Fig. 4, the core bar B has a double structure consisting of a thin first core bar 1 and a second core bar 2. The inner peripheral surface 1B of the first core bar 1 is exposed, and the inner peripheral surface 1B is attached to the outer peripheral surface of a nut member of a ball screw of a power transmission mechanism of an electric power steering device (not shown), and is used for radial positioning of the toothed pulley A with respect to the nut of the ball screw. The first core bar 1 and the second core bar 2 are made by pressing a cold-rolled steel plate, a hot-rolled steel plate, a high-tensile steel plate, or the like.

[0042] The second core bar 2 is located outward in the radial direction H from the first core bar 1 so as to leave a gap G (FIG. 3B) in the radial direction H relative to the first core bar 1, and is concentric (coaxial) with the first core bar 1. In other words, the gap G is between an outer peripheral surface 1A of the first core bar 1 and an inner peripheral surface 2B of the second core bar 2.

[0043] The first core bar 1 has a bottom plate 3 at one end in the axial direction J. The bottom plate 3 has a plurality of mounting holes 3A in the axial direction J (in this embodiment, four circular holes equally spaced in the circumferential direction) and a plurality of holes 3B (in this embodiment, four circumferential elongated holes equally spaced in the circumferential direction) into which the resin part C is inserted.

[0044] The toothed pulley A can be easily and reliably fixed to the member to which it is attached by a bolt passed through the mounting hole 3A of the first core bar 1. Furthermore, the weight of the first core bar 1, which is a cylindrical shape with a bottom, can be reduced by the punching hole 3B of the first core bar 1. Furthermore, by inserting the resin part C into the punching hole 3B, it also has the function of preventing the resin part C including the teeth T and the first core bar 1 from rotating in the circumferential direction.

[0045] The first core bar 1 has an outward flange D (Figs. 2, 3B, 4) at the other end in the axial direction J that protrudes outward in the radial direction H. A radial outer peripheral surface M of the outward flange D of the first core bar 1 is located further inward in the radial direction H than the inner peripheral surface 2B of the second core bar 2. By providing the outward flange D on the first core bar 1, the rigidity of the first core bar 1 is improved and the first core bar 1 can be prevented from coming off in the axial direction J from the resin part C.

[0046] The second core bar 2 has an outward flange E (FIGS. 2, 3B, and 4) at one end in the axial direction J. By providing the outward flange E on the second core bar 2, the rigidity of the second core bar 2 is improved and the second core bar 2 is prevented from coming off in the axial direction J from the resin part C.

[0047] <Rotation-prevention shape> As shown in the axial view of Fig. 5A and the enlarged explanatory view of the main part of Fig. 5B, in this embodiment, the radial outer peripheral surface M of the outward flange D of the first core bar 1 has a shape in which a part of a cylindrical surface U is cut off by a plane N1 perpendicular to the radial direction H, and has eight equally divided planes N1 in the circumferential direction. In other words, the planes N1 are parts displaced inward in the radial direction H from the cylindrical surface U.

[0048] The radial outer peripheral surface M of the outward flange D has a shape including a plurality of portions N1 displaced inward in the radial direction H from the cylindrical surface U, and this shape forms an anti-rotation shape F in the circumferential direction I with the resin part C. In other words, by covering the radial outer peripheral surface M of the outward flange D of the first core bar 1 (anti-rotation shape F in the circumferential direction I) with the resin part C, it is possible to prevent the first core bar 1 and the resin part C from rotating in the circumferential direction I.

[0049] When the resin part C is injection molded, it is desirable to set the confluence (weld) of the molten resin to be located on plane N1. This is because the strength of the confluence of the resin part C is reduced, and the confluence is removed from the position where the stress in the rotational direction is large by preventing rotation in the circumferential direction I.

[0050] The radial outer peripheral surface M (anti-rotation shape F in the circumferential direction I) of the outward flange D of the first core bar 1 may have a shape having a plurality of teeth W in the circumferential direction, i.e., a shape having a plurality of tooth-shaped irregularities, as shown in the perspective views of Figures 6A and 6B. In the example of Figure 6A, the arc-shaped recessed surface N2 is a portion displaced inward in the radial direction H from the cylindrical surface U (Figure 5B), and in the example of Figure 6B, the trapezoidally recessed surface N3 is a portion displaced inward in the radial direction H from the cylindrical surface U (Figure 5B).

[0051] In the toothed pulley A according to the first embodiment of the present invention, the shape of the radial outer circumferential surface M of the outward flange D of the core B, i.e., the shape including a plurality of portions (e.g., N1 to N3) displaced inward in the radial direction H from the cylindrical surface U, can be formed by pressing. Therefore, there is no need to perform post-processing such as knurling after pressing, and therefore the manufacturing cost does not increase.

[0052] Furthermore, since the radial outer circumferential surface M of the outward flange D of the core B has a shape including a plurality of portions displaced inward in the radial direction H from the cylindrical surface U, it is possible to reduce the outward protruding length of the outward flange D in the radial direction H. Therefore, since the thickness of the resin part C in the radial direction H does not increase, the difference in thickness with respect to the total tooth depth becomes small, and the shrinkage difference is also small, making it easy to satisfy the required specifications for the accuracy of the teeth T of the toothed pulley A.

[0053] In this embodiment, the radial outer peripheral surface V of the outward flange E (FIGS. 2, 3B, 4) of the second core bar 2 is a cylindrical surface. The radial outer peripheral surface V of the outward flange E of the second core bar 2 may be formed with the anti-rotation shape F in the circumferential direction I, similar to the radial outer peripheral surface M of the outward flange D of the first core bar 1. In this way, by covering the anti-rotation shape F in the circumferential direction I of the radial outer peripheral surface V of the outward flange E of the second core bar 2 with the resin part C, it is possible to prevent rotation between the second core bar 2 and the resin part C in the circumferential direction I.

[0054] Alternatively, instead of forming the outward flange E on the second core bar 2, an inward flange protruding radially inward may be formed, and the radially inner peripheral surface of the inward flange may be shaped to include a plurality of portions displaced radially outward from the cylindrical surface. This shape is also a circumferential rotation prevention shape, and by covering this circumferential rotation prevention shape with the resin part C, it is possible to prevent rotation of the second core bar 2 and the resin part C in the circumferential direction I.

[0055] With these configurations, the above-mentioned shape of the radial outer peripheral surface V of the outward flange E of the second core wire 2 or the above-mentioned shape of the radial inner peripheral surface of the inward flange can prevent rotation in the circumferential direction I between the second core wire 2 and the resin portion C.

[0056] In addition, the outward flange of the second core bar 2 E The shape of the radial outer peripheral surface V of the second core bar 2 or the shape of the radial inner peripheral surface of the inward flange of the second core bar 2 can be formed by pressing. Therefore, there is no need to perform post-processing such as knurling after pressing, and the manufacturing cost does not increase.

[0057] Furthermore, since the shape of the radial outer peripheral surface V of the outward flange E of the second core bar 2 includes a plurality of portions displaced radially inward from a cylindrical surface, it is possible to reduce the radially outward protruding length of the outward flange E. Alternatively, since the shape of the radial inner peripheral surface of the inward flange of the second core bar 2 includes a plurality of portions displaced radially outward from a cylindrical surface, it is possible to reduce the radially inward protruding length of the inward flange. Therefore, since the thickness of the resin part C in the radial direction H does not increase, the difference in thickness with respect to the total tooth depth becomes small, and the shrinkage difference is also small, so that it is easy to satisfy the required specifications for the tooth accuracy of the toothed pulley A.

[0058] <Resin part> As shown in the partial cross-sectional perspective view of Fig. 2, the vertical cross-sectional view of Fig. 3A, and the enlarged vertical cross-sectional view of the main part of Fig. 3B, the resin part C is the same part including the resin in the gap G between the first core bar 1 and the second core bar 2, and the teeth T. The material of the resin part C is, for example, a thermoplastic resin material such as PBT, PA6, PA66, PA46, PPS, or PEEK, and among them, a preferred embodiment is one in which PPS, which is excellent in heat resistance, mechanical properties, flame retardancy, dimensional stability, etc., is blended with several tens of weight percent of glass fiber as a reinforcing material. The resin part C is formed by injection molding in a state in which the core bar B, which is an insert product, is set in an injection molding die.

[0059] The resin part C has an outward flange R at one axial end that protrudes outward in the radial direction H beyond the tips of the teeth T. Also, a fitting recess P of an outward flange S made of synthetic resin is fitted into a fitting protrusion Q at the other axial end of the resin part C, and with the outward flange S positioned axially and radially relative to the resin part C, the outward flange S is attached to the resin part C by, for example, ultrasonic welding. Therefore, the toothed pulley A is a double flange type, and the axial movement of the toothed belt meshing with the toothed pulley A can be restricted.

[0060] The resin part C has a bottom plate K at one end in the axial direction, and the bottom plate K has a notch L that exposes the mounting hole 3A of the bottom plate 3 of the first core bar 1 in the axial direction. The bottom plate K provided in the resin part C increases the strength and rigidity of the resin part C. In addition, since the notch L is provided in the bottom plate K of the resin part C, the mounting hole 3A of the bottom plate 3 of the first core bar 1 is exposed in the axial direction, so the bottom plate K of the resin part C does not get in the way when attaching the toothed pulley A to the member to which the toothed pulley A is to be attached.

[0061] <Effects of the double-layered core> Since the cylindrical core B of the toothed pulley A is the first core 1 and the second core 2, the core can be made thin, thereby reducing the weight of the toothed pulley A. Furthermore, since the resin portion C is a thermoplastic resin, the productivity of the toothed pulley A is increased.

[0062] Furthermore, the cylindrical core B is composed of a first core 1 that forms the inner diameter of the toothed pulley A, and a second core 2 that is located radially outward from the first core 1. Therefore, the second core 2 allows the thickness of the resin part C located radially outward from it to be appropriately set, making it easy to ensure the required precision of the teeth T of the toothed pulley A.

[0063] [Embodiment 2]

[0064] <Toothed pulley> As shown in the perspective view of Fig. 7, the partial sectional perspective view of Fig. 8, the vertical sectional view of Fig. 9A, the enlarged vertical sectional view of a main portion of Fig. 9B, and the perspective view of Fig. 10, a toothed pulley A according to embodiment 2 of the present invention is made up of a cylindrical core B and a resin part C including teeth T. Unlike the toothed pulley A according to embodiment 1, the toothed pulley A according to embodiment 2 of the present invention does not have a double-structure core B. In Figs. 7 to 11B showing embodiment 2, the same reference numerals as those in Figs. 1 to 6B showing embodiment 1 indicate the same or corresponding parts or portions.

[0065] <Rotation-prevention shape> As shown in the axial view of Fig. 11A and the enlarged explanatory view of the essential parts of Fig. 11B, in this embodiment, the radial outer peripheral surface M of the outward flange D of the core B has a shape obtained by cutting a cylindrical surface U by a plane perpendicular to the radial direction H, and has 16 equally divided circumferential planes N4. In other words, the planes N4 are portions displaced inward in the radial direction H from the cylindrical surface U. The shape of the radial outer peripheral surface M of the outward flange D of the core B is a hexagon when viewed from the axial direction J.

[0066] The radial outer peripheral surface M of the outward flange D has a shape including a plurality of portions N4 displaced inward in the radial direction H from the cylindrical surface U, and this shape forms a rotation prevention shape F in the circumferential direction I with the resin part C. In other words, by covering the radial outer peripheral surface M (rotation prevention shape F in the circumferential direction I) of the outward flange D of the core B with the resin part C, it is possible to prevent rotation in the circumferential direction I between the first core B 1 and the resin part C.

[0067] The anti-rotation shape F in the circumferential direction I is not limited to the shapes shown in Figs. 5A and 5B, 6A and 6B, and 11A and 11B, and may be a curved surface as viewed from the axial direction J, or may be a combination of a flat surface and a curved surface as viewed from the axial direction J. That is, when the radial outer peripheral surface M of the outward flange D of the first core bar 1, the radial outer peripheral surface M of the outward flange D of the core bar B, and the radial outer peripheral surface V of the outward flange E of the second core bar 2 are formed into the anti-rotation shape F in the circumferential direction I, the radial outer peripheral surface V may have a shape including a plurality of parts displaced radially inward from a cylindrical surface. When the second core bar 2 is formed with an inward flange to prevent rotation in the circumferential direction I, the radial inner and outer peripheral surfaces may have a shape including a plurality of parts displaced radially outward from a cylindrical surface. The anti-rotation shape F in the circumferential direction I is formed by pressing or machining.

[0068] The above description of the embodiments is given by way of example only and is not intended to be limiting, and various improvements and modifications can be made without departing from the scope of the present invention. [Explanation of symbols]

[0069] 1 1st core metal 1A Outer surface 1B Inner surface 2 Second core metal 2A Outer surface 2B Inner surface 3 Bottom plate 3A Mounting hole 3B Punch hole A Toothed pulley B Core metal C Resin part D Outward flange E Outward flange F Anti-rotation shape G Gap H Radial direction I circumferential direction J-axis direction K bottom plate L notch M Radial outer surface N1, N4 plane (part displaced radially inward) N2: Arc-shaped concave surface (part displaced radially inward) N3: Trapezoidally recessed surface (part displaced radially inward) O Rotation axis P Fitting recess Q Fitting protrusion R Outward flange S Outward flange T tooth U Cylindrical surface V Radial outer surface W tooth

Claims

1. A toothed pulley that is required to have high tooth precision and is made of a cylindrical core metal and a resin portion including teeth, The core metal has an outward flange protruding radially outward at an axial end thereof, The radial outer circumferential surface of the outward flange has a shape including a plurality of portions displaced radially inward from a cylindrical surface, a radial outer circumferential surface of the core metal including the outward flange is covered with the resin portion; The radial inner peripheral surface of the core metal is exposed, The core metal has a bottom plate at one end in the axial direction, The bottom plate of the core metal has a plurality of axial mounting holes and a plurality of holes into which the resin portion is inserted, The resin portion has a bottom plate at one end in the axial direction, a bottom plate of the resin portion has a notch for exposing the mounting hole of the bottom plate of the core metal in the axial direction; Toothed pulley.

2. A toothed pulley that is required to have high tooth precision and is made of a cylindrical core metal and a resin portion including teeth, The core metal has an outward flange protruding radially outward at an axial end thereof, The radial outer circumferential surface of the outward flange has a shape including a plurality of portions displaced radially inward from a cylindrical surface, a radial outer circumferential surface of the outward flange is covered with the resin portion, The core metal is A first core bar; a second core bar that is concentric with the first core bar and is located radially outward from the first core bar so as to have a radial gap therebetween; It consists of: the first core metal has the outward flange at an axial end, The resin portion is It is a thermoplastic resin, The resin in the gap between the first core bar and the second core bar and the resin in the teeth are the same part. Toothed pulley.

3. the second core bar has an outward flange protruding radially outward or an inward flange protruding radially inward at one end or the other end in the axial direction, The radial outer circumferential surface of the outward flange has a shape including a plurality of portions displaced radially inward from a cylindrical surface, The radially inner peripheral surface of the inward flange has a shape including a plurality of portions displaced radially outward from a cylindrical surface, A radial outer peripheral surface of the outward flange or a radial inner peripheral surface of the inward flange is covered with the resin portion.

3. A toothed pulley according to claim 2.

4. The first core bar has a bottom plate at one end in the axial direction, The bottom plate has a plurality of axial mounting holes and a plurality of holes into which the resin portion is inserted.

4. A toothed pulley according to claim 2 or 3.

5. The resin portion has a bottom plate at one end in the axial direction, a bottom plate of the resin portion has a notch for exposing the mounting hole of the bottom plate of the first core bar in the axial direction; 5. A toothed pulley according to claim 4.

6. The resin portion is An outward flange is provided at one end in the axial direction and protrudes radially outward beyond the tips of the teeth. A toothed pulley according to any one of claims 1 to 5.

Images