JP2012107701A - Synthetic resin pulley - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthetic resin pulley which can be reduced in weight and can avoid a concentration of stress to an offset load.SOLUTION: The pulley 2 comprises: an outside-diameter side cylinder 4; an inside-diameter side cylinder 6; a connecting part 8 which connects the cylinders to the axial direction at a prescribed thickness T; and plurality of ribs 10 which are radially protruded to the peripheral face 8s of the connecting part in the axial direction with respect to the circumferential direction at a prescribed thicknesses, connected to the outside-diameter side cylinder at their outside-diameter sides, and connected to the inside diameter-side cylinder at their inside-diameter sides. Each rib has an outside-diameter side protruded end-face arc 14 and an internal-diameter side protruded end-face arc 16 which connect an internal peripheral face and an outside peripheral face by axially recessing a portion in which an axial protruded end face 10s is continuous to the internal peripheral face of the outside-diameter side cylinder and a portion in which the axial protruded end face is continuous to the external peripheral face of the inside-diameter side cylinder. The outside-diameter side protruded end-face arc is gradually lowered in its protrusion height from the peripheral face of the connecting part as progressing toward an inside-diameter side from an outside-diameter end, and the inside-diameter side protruded end-face arc is lowered in its protrusion height from the peripheral face of the connecting part as progressing toward the outside-diameter side from an inside-diameter end, respectively.

Description

  The present invention relates to a belt transmission mechanism, for example, a mechanism for driving an auxiliary machine such as an air conditioner compressor by an endless belt in an automobile, or a crank pulley fixed to an end of a crankshaft and an end of a camshaft. The present invention relates to improvements in synthetic resin guide pulleys, tension pulleys, and the like used by being incorporated in a mechanism for transmitting rotational force to and from a cam pulley by a timing belt.

As pulleys such as guide pulleys and tension pulleys incorporated and used in a belt transmission mechanism, synthetic resin pulleys have been conventionally used in order to reduce the weight and cost (see Patent Document 1).
FIG. 4 shows a configuration example of a pulley device incorporating such a synthetic resin pulley. Such a pulley device includes a synthetic resin pulley 50 for suspending a belt on an outer peripheral surface, and a bearing (for example, a single row deep groove type) for rotatably supporting the pulley 50 on a support shaft (not shown). (Radial ball bearing) 70. The bearing 70 includes an inner ring 72 having a single row inner ring raceway 72r on the outer peripheral surface, an outer ring 74 having an outer ring raceway 74r facing the inner ring raceway 72r on the inner peripheral surface, and a space between the inner ring raceway 72r and the outer ring raceway 74r. A plurality of rolling elements (balls as an example) 76 are provided so as to be freely rotatable. A pulley 50 is fixed to the outer peripheral portion of the outer ring 74 of the bearing 70.

  The pulley 50 includes two cylindrical portions (an outer diameter side cylindrical portion 52 and an inner diameter side cylindrical portion 54) arranged so as to be concentric with each other, and an annular connecting portion that connects the cylindrical portions 52 and 54 to each other. 56. The connecting portion 56 is between an intermediate portion in the axial direction (left and right direction in FIG. 4) of the inner peripheral surface of the outer diameter side cylindrical portion 52 and an intermediate portion in the axial direction of the outer peripheral surface of the inner diameter side cylindrical portion 54. The circumferential area is extended with a predetermined thickness (thickness with respect to the axial direction). A plurality of reinforcing pieces (ribs) 58 project radially from the circumferential surface portions on both sides in the axial direction of the connecting portion 56 in the axial direction with a predetermined thickness in the circumferential direction. These ribs 58 are connected to the inner peripheral surface of the outer diameter side cylindrical portion 52 on the outer diameter side and to the outer peripheral surface of the inner diameter side cylindrical portion 54 on the inner diameter side. Each rib 58 has an end surface 58s (a projecting end surface in the axial direction, hereinafter referred to as an axial projecting end surface) 58s opposite to the peripheral surface portion of the connecting portion 56 with respect to the axial direction. The part which continues to the inner peripheral surface of this is a structure in which it is recessed toward the peripheral surface side of the connecting portion 56 in the axial direction. That is, the continuous portion is a connection portion between the ribs 58 and the inner peripheral surface of the outer diameter side cylindrical portion 52 (J1 shown in FIG. 4) and the connection between the ribs 58 and the outer peripheral surface of the inner diameter side cylindrical portion 54. It is curved so as to be recessed toward the peripheral surface side of the connecting portion 56 with respect to the axial direction rather than a virtual conical curved surface (S) having a straight line connecting the part (J2) as a generatrix (hereinafter referred to as the curve). The portion is referred to as a curved portion 58r). By these curved portions 58r, the outer diameter side end portion of the axially projecting end surface 58s of each rib 58 and the inner peripheral surface of the outer diameter side cylindrical portion 52 are smoothly continued.

By the way, when the synthetic resin pulley 50 is used, the strength of the device itself is inferior to that when a metal pulley is used. For this reason, while extending the connection part 56 between the inner peripheral surface of the outer diameter side cylindrical part 52 and the outer peripheral surface of the inner diameter side cylindrical part 54, and interposing a plurality of ribs 58, the strength of the pulley 50 is increased. We are trying to improve.
Further, by forming the curved portion 58r for each rib 58, the pulley 50 is saved in space, and as a result, its weight is reduced. That is, the rib 58 can be made smaller by the curved portion 58r as compared with the pulley configuration in which the axially projecting end surface 58s of the rib 58 coincides with the virtual conical curved surface S, and interference with peripheral members is also prevented. A possible configuration.

However, when the curved portion 58r is formed on each rib 58 in this way, a rib structure that does not form the curved portion 58r (for example, the axially projecting end surface 58s of the rib 58 is made to coincide with the virtual conical curved surface S. Compared to the rib structure), the strength of the pulley 50 is likely to decrease. Therefore, for example, when an excessive load is applied from the endless belt spanned over the pulley 50, the pulley 50 bends along the curved portion 58r of a part of the rib 58, and the axially projecting end surface 58s of the rib 58 is obtained. However, there is a possibility that damage such as breakage may occur in a portion (ends curved portion 58r) that is continuous with the inner peripheral surface of the outer diameter side cylindrical portion 52.
Therefore, in addition to forming the curved portion 58r with respect to the rib 58 as described above, both sides in the circumferential direction of the portion where the outer diameter side of the rib 58 is coupled to the inner peripheral surface of the outer diameter side cylindrical portion 52 (rib Also known is a pulley configuration that improves the strength by smoothly continuing the outer circumferential side ends of the outer circumferential side of the outer circumferential surface of the outer circumferential surface of the outer circumferential surface 58 (hereinafter, the concave arc-shaped portion is referred to as the outer circumferential side circular arc portion). (See Patent Document 2).

JP 2008-290402 A JP 2005-127465 A

  However, even in the case of the pulley configuration in which the outer diameter side circumferential arc portion is formed in addition to the curved portion 58r in this way, for example, when the load applied from the endless belt spanned over the pulley 50 is offset, The stress against the offset load may be concentrated on a portion where the axially projecting end surface 58s of the rib 58 and the outer peripheral surface of the inner diameter side cylindrical portion 54 are continuous (portion indicated by J2 in FIG. 4). Therefore, even in the case of such a configuration, when an offset load as described above is applied, the stress against the offset load is avoided from being concentrated at a specific location (particularly, the continuous portion), and the stress It cannot be denied that it is insufficient to alleviate this.

  The present invention has been made to solve such a problem, and its purpose is to reduce the weight while avoiding stress concentration on the offset load even when the offset load is applied, It is an object of the present invention to provide a synthetic resin pulley capable of reliably relieving the stress over the entire pulley.

  In order to achieve such an object, the synthetic resin pulley according to the present invention includes an outer diameter side cylindrical portion for suspending a belt on an outer peripheral surface, and an outer diameter side on the inner diameter side of the outer diameter side cylindrical portion. A circumferential region between an inner diameter side cylindrical portion arranged concentrically with the cylindrical portion, an axial intermediate portion of the inner peripheral surface of the outer diameter side cylindrical portion, and an axial intermediate portion of the outer peripheral surface of the inner diameter side cylindrical portion An annular connecting portion that extends with a predetermined thickness in the axial direction and connects the outer diameter side cylindrical portion and the inner diameter side cylindrical portion, and a radial portion on each of the peripheral surface portions on both axial sides of the connecting portion. And a plurality of ribs protruding in the axial direction with a predetermined thickness with respect to the circumferential direction, the outer diameter side being coupled to the outer diameter side cylindrical portion, and the inner diameter side being coupled to the inner diameter side cylindrical portion. In such a synthetic resin pulley, the rib includes a portion in which an axially projecting end surface is continuous with the inner peripheral surface of the outer diameter side cylindrical portion, and the inner periphery of the outer diameter side cylindrical portion is recessed in the axial direction. An outer-diameter-side projecting end surface arc portion to be coupled to the surface, and a portion where the projecting end surface continues to the outer peripheral surface of the inner-diameter-side cylindrical portion is recessed in the axial direction to It has an inner diameter side protruding end face arc portion to be coupled. The outer-diameter-side protruding end surface arc portion has a concave arc shape in which the protruding height from the peripheral surface portion of the connecting portion gradually decreases from the outer-diameter end toward the inner-diameter side, and The installation end surface arc portion has a concave arc shape in which the protruding height from the peripheral surface portion of the connecting portion gradually decreases from the inner diameter end toward the outer diameter side.

In this case, it is preferable that the curvature radius of the outer diameter side arc portion is set to 5 mm or more and 14 mm or less, and the curvature radius of the inner diameter side arc portion is set to 1 mm or more and 20 mm or less.
Further, the outer diameter side arc portion and the inner diameter side arc portion may be smoothly continuous so that the entire projecting end surface of the rib has one concave curved surface shape in the axial direction.
Furthermore, what is necessary is just to set the thickness with respect to the axial direction of the said connection part larger than the thickness with respect to the circumferential direction of the said rib.

  According to the present invention, it is possible to avoid concentration of stress with respect to the offset load and to surely relieve the stress throughout the pulley even when the offset load is applied while reducing the weight. A resin pulley can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the synthetic resin pulley which concerns on one Embodiment of this invention, Comprising: (a) is principal part sectional drawing, (b) is an outer diameter side protrusion end surface circular arc part and an inner diameter side protrusion end surface. It is explanatory drawing of the curvature radius set to a circular arc part. It is principal part sectional drawing. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the synthetic resin pulleys concerning one Embodiment of this invention, Comprising: (a) is a top view which shows the whole structure, (b) expands the principal part of the same figure (a). FIG. It is a figure which shows the test result for verifying the stress relaxation effect of the synthetic resin pulley which concerns on one Embodiment of this invention for every test subject (pulley). It is sectional drawing which shows the structure of the conventional synthetic resin pulleys.

  Hereinafter, the synthetic resin pulley of the present invention will be described with reference to the accompanying drawings. A synthetic resin pulley according to the present invention includes a predetermined belt transmission mechanism, for example, a mechanism for driving an auxiliary machine such as an air conditioner compressor by an endless belt in a car, a crank pulley fixed to an end of a crankshaft, It can be assumed that it is used by being incorporated in a mechanism that transmits rotational force with a timing belt between the cam pulley fixed to the end of the camshaft, that is, configured as a guide pulley, a tension pulley, etc. It is not limited to this. As the synthetic resin constituting the pulley according to the present invention, polyamide resins such as polyamide 6, polyamide 66, polyamide 46, polyamide 12 and polyamide 612, linear or branched polyphenylene sulfide resin, and the like are used. Is possible. Also, two or more types of polyamide resins may be mixed and used in order to improve low water absorption, fatigue resistance and molding accuracy. Further, in order to increase the strength, the above-mentioned various synthetic resins may be filled with a fibrous filler (for example, glass fiber or carbon fiber) or a particulate filler (for example, silica or alumina).

1 and 2 show a configuration of a synthetic resin pulley (hereinafter also simply referred to as a pulley) 2 according to an embodiment of the present invention.
The pulley includes an outer diameter side cylindrical portion 4 for suspending the belt on the outer peripheral surface, and an inner diameter side cylindrical portion 6 arranged concentrically with the outer diameter side cylindrical portion 4 on the inner diameter side of the outer diameter side cylindrical portion 4. Between the intermediate portion in the axial direction of the inner peripheral surface of the outer diameter side cylindrical portion 4 (left and right direction in FIG. 1A) and the intermediate portion in the axial direction of the outer peripheral surface of the inner diameter side cylindrical portion 6. An annular connecting portion 8 that extends to the circumferential area with a predetermined thickness (dimension T shown in the figure) in the axial direction and connects the outer diameter side cylindrical portion 4 and the inner diameter side cylindrical portion 6. In addition, the peripheral surface portions 8s on both sides in the axial direction of the connecting portion 8 are radially projected in the axial direction with a predetermined thickness (dimension W shown in FIG. 2B) in the circumferential direction, and the outer diameter side is An outer diameter side cylindrical portion 4 and a plurality of ribs 10 each having an inner diameter side coupled to the inner diameter side cylindrical portion 6 are provided.

  In this case, the width dimension of the outer diameter side cylindrical portion 4 in the axial direction is set to be larger over the entire circumference than the width dimension of the inner diameter side cylindrical portion 6 in the axial direction. The inner diameter side cylindrical portion 6 keeps the thickness in the radial direction (the difference between the outer diameters of the cylindrical portions 4 and 6) constant, and the axial intermediate portions thereof have the same phase with respect to the axial direction. Is arranged. It should be noted that the outer diameter of each of the outer diameter side cylindrical portion 4 and the inner diameter side cylindrical portion 6, the thickness in the radial direction, the width in the axial direction, etc. are arbitrarily set according to the configuration of the belt transmission mechanism in which the pulley 2 is incorporated. There is no particular limitation here. FIG. 2A shows the configuration of the pulley 2 in which 48 ribs 10 (assuming 96 on both sides in the axial direction) are protruded from the peripheral surface portion 8 s on one axial direction side of the connecting portion 8. The number of protruding ribs 10 is not limited to this, and may be set arbitrarily. Regardless of the number of protrusions, these ribs 10 are radially arranged on the peripheral surface portion 8s of the connecting portion 8 at equal intervals, and the same number in the circumferential direction is the same in the two peripheral surface portions 8s on both axial sides. It is preferable that they are arranged in a phase and arranged in pairs.

A bearing 12 is disposed on the inner peripheral portion of the inner diameter side cylindrical portion 6, and the pulley 2 is rotatably supported by the bearing 12 on a support shaft (not shown) of the belt transmission mechanism. In FIG. 1A, a configuration in which a single-row deep groove type radial ball bearing is applied as the bearing 12 is shown as an example, but the bearing configuration is not limited thereto. In short, as long as the pulley 2 can be rotatably supported with respect to the support shaft of the belt transmission mechanism, any bearing configuration (for example, bearing type, shape of outer and inner rings and rolling elements, presence or absence of a cage and a sealing member) It doesn't matter if it doesn't matter.
The pulley 2 and the bearing 12 constitute one pulley device. The pulley device is configured such that the inner ring 12a of the bearing 12 is externally fitted and fixed to a predetermined support shaft (for example, a shaft disposed on a fixed portion of an engine cylinder block), and the outer diameter side cylindrical portion 4 of the pulley 2 is fixed. In a state where an endless belt (not shown) is bridged on the outer peripheral surface of the belt, the pulley 2 is rotated as the endless belt travels, and the winding angle and tension of the belt are adjusted and secured.

  In the pulley 2, the inner cylindrical portion 6 is fixed to the outer peripheral portion of the outer ring 12 b of the bearing 12 by injection molding. That is, the bearing 12 is used as an insert part, and the outer ring 12b is molded on the inner peripheral side of the molded body (the structure that becomes the pulley 2 after molding), and corresponds to the outer shape of the pulley 2 provided in the mold. The above-mentioned various synthetic resins (thermoplastic resins) that have been melted are injected into the cavity having the inner shape. Then, after the injected thermoplastic resin is cooled and solidified, the mold is opened, and the pulley 2 as a molded body is taken out of the cavity together with the bearing 12.

  In the present embodiment, the rib 10 is formed by denting a portion in which the axially projecting end face 10 s is continuous with the inner peripheral surface of the outer diameter side cylindrical portion 4 in the axial direction. The outer-diameter-side projecting end surface arc portion 14 to be coupled to the surface and the portion where the projecting end surface 10s is continuous with the outer peripheral surface of the inner-diameter-side cylindrical portion 6 are recessed in the axial direction to It has an inner diameter side protruding end surface arc portion 16 to be coupled to the outer peripheral surface. The projecting end surface arc portion 14 of the outer diameter side protrudes from the outer surface end 8s of the connecting portion 8 from the outer diameter end (the upper end in FIG. 1A) toward the inner diameter side (same as the lower side). And the inner diameter side protruding end surface arc portion 16 from the peripheral surface portion 8s of the connecting portion 8 from the inner diameter end (same, lower end) toward the outer diameter side (same, upper side). It has a concave arc shape in which the projecting height of the is gradually reduced. That is, the projecting end surface 10 s of the rib 10 is connected to the inner peripheral surface of the outer-diameter-side cylindrical portion 4 in a so-called R shape by the outer-diameter-side projecting end-surface arc portion 14, and the inner-diameter-side projecting end-surface arc portion 16 It continues to the outer peripheral surface of the cylindrical portion 6 in a so-called R shape.

  Note that the radius of curvature R1 of the outer-diameter-side projecting end surface arc portion 14 formed on the projecting end surface 10s of the rib 10 and the radius of curvature R2 of the inner-diameter-side projecting end surface arc portion 16 are the material of the pulley 2 and the size of the rib 10. It is possible to set arbitrarily according to the situation (FIG. 1B). For example, the outer radius side protruding end surface arc portion 14 has a curvature radius R1 set to 5 mm or more and 14 mm or less, and the inner diameter side protruding end surface arc portion 16 has a curvature radius R2 set to 1 mm or more and 20 mm or less. do it. At this time, the radius of curvature R1 of the outer-diameter-side projecting end surface arc portion 14 and the radius of curvature R2 of the inner-diameter-side projecting end surface arc portion 16 may be set to be the same for all the ribs 10 (projecting end surface 10s). . However, these curvature radii R1 and R2 can be set differently for each predetermined rib 10. For example, the outer-diameter-side protruding end surface arc portion 14 and the inner-diameter-side projection set to a plurality of curvature radii R1, R2 (for example, R1 is set to 5 mm, R2 is set to 1 mm, and R1 is set to 10 mm, R2 is set to 3 mm) A plurality of sets (for example, two sets as described above) of ribs 10 having different curvature radii R1 and R2 are respectively formed in the projecting end face 10s on the projecting end face arc portion 16s with a predetermined phase in the circumferential direction ( As an example, it is also possible to assume a configuration in which they are arranged alternately.

Further, as shown in FIG. 1 (a), the outer-diameter-side protruding end surface arc portion 14 has a configuration in which the outer-diameter end (the upper end in the figure) coincides with the inner peripheral edge of the outer-diameter-side cylindrical portion 4. The inner-diameter-side protruding end surface arc portion 16 preferably has a configuration in which the inner-diameter end (the same lower end) coincides with the outer peripheral edge of the inner-diameter-side cylindrical portion 6. With such a configuration, a portion where a protruding end surface 10s of the rib 10 described later and an inner peripheral surface of the outer diameter side cylindrical portion 4 are continuous, and an outer peripheral surface of the protruding end surface 10s and the inner diameter side cylindrical portion 6 are provided. It is possible to further enhance the effect of mitigating the stress acting on the continuous portion. However, the outer diameter end projecting end surface arc portion 14 has an outer diameter end on the inner peripheral surface of the outer diameter side cylindrical portion 4, and the inner diameter side projecting end surface arc portion 16 has an inner diameter end of the inner diameter side cylindrical portion 6. It is also possible to assume a configuration on the outer peripheral surface.
The outer-diameter-side projecting end surface arc portion 14 and the inner-diameter-side projecting end surface arc portion 16 may be continuous via a predetermined concave portion (step portion), convex portion (corner portion), or the like. It is preferable that the entire projecting end surface 10s of the rib 10 has a single concave curved surface shape in the axial direction. That is, the projecting end surface 10 s of the rib 10 extends from the portion continuous with the inner peripheral surface of the outer diameter side cylindrical portion 4 (the outer diameter end of the outer diameter side protruding end surface arc portion 14) to the outer peripheral surface of the inner diameter side cylindrical portion 6. It is preferable that the entire surface up to the continuous portion (the inner diameter end of the inner diameter side protruding end surface arc portion 16) is configured to be smoothly recessed as a whole by continuing two arcs.

  In the present embodiment, the thickness T of the connecting portion 8 in the axial direction is set larger than the thickness W of the rib 10 in the circumferential direction (T> W). In this case, the connecting portion 8 is uniform over the entire circumferential area between the axial intermediate portion of the inner peripheral surface of the outer diameter side cylindrical portion 4 and the axial intermediate portion of the outer peripheral surface of the inner diameter side cylindrical portion 6. The ribs 10 are radially projected on the peripheral surface 8s of the connecting portion 8 with the same thickness (thickness in the circumferential direction) W. What is necessary is just to comprise so that the thickness T of this connection part 8 may become larger than the thickness W of these ribs 10. FIG. The thickness T of the connecting portion 8 and the thickness W of the rib 10 are as long as the thickness T of the connecting portion 8 is set larger than the thickness W of the rib 10. It can be arbitrarily set according to the size and material, and is not particularly limited.

  In this way, by forming the outer-diameter-side projecting end surface arc portion 14 and the inner-diameter-side projecting end surface arc portion 16 with respect to the projecting end surface 10 s of the rib 10, for example, the load is applied from the endless belt spanned over the pulley 2. Even if the load to be applied (for example, moment load) is offset, the stress applied to the offset load is a portion where the projecting end surface 10s of the rib 10 and the inner peripheral surface of the outer diameter side cylindrical portion 4 are continuous. In addition, the stress is applied to the entire outer diameter side projecting end surface arc portion 14 and inner diameter side projecting end surface arc portion 16 without concentrating only on the portion where the projecting end surface 10s and the outer peripheral surface of the inner diameter side cylindrical portion 6 are continuous. Can act. That is, such stress can be dispersed throughout the outer diameter side protruding end surface arc portion 14 and the inner diameter side protruding end surface arc portion 16, and the stress acting on the continuous portion can be relaxed.

  Further, by setting the thickness T in the axial direction of the connecting portion 8 larger than the thickness W in the circumferential direction of the rib 10, the stress can be effectively released to the connecting portion 8. The stress acting on the can be reduced. As a result, the protruding end surface 10s of the rib 10 and the inner peripheral surface of the outer diameter side cylindrical portion 4 are continuous, and the protruding end surface 10s and the outer peripheral surface of the inner diameter side cylindrical portion 6 are continuous. The stress can be further relaxed.

  In addition, in the present embodiment, as shown in FIG. 2, not only the outer diameter side protruding end surface arc portion 14 and the inner diameter side protruding end surface arc portion 16 are formed on the protruding end surface 10 s, In addition to providing an outer diameter side circumferential arc 20 that smoothly connects both sides in the circumferential direction (both ends of the rib 10 on the outer diameter side in the circumferential direction) of the portion where the diameter side is coupled to the outer diameter side cylindrical portion 4, An inner diameter side circumferential arc portion 22 is provided that smoothly connects both sides in the circumferential direction of the portion where the inner diameter side of the rib 10 is coupled to the inner diameter side cylindrical portion 6 (both inner diameter direction circumferential ends of the rib 10) in a concave arc shape. . Thereby, the strength of the outer diameter side circumferential end portions and the inner diameter side circumferential end portions of the rib 10 is increased, and the outer diameter side projecting end surface arc portion 14 and the inner diameter side projecting end surface arc portion 16 are formed. The reduction in the strength of the pulley 2 that may occur due to the downsizing of the rib 10 is prevented.

  As described above, in the present embodiment, it is assumed that the pulley 2 is molded by injecting various synthetic resins (thermoplastic resins). When the pulley 2 is injection-molded in this way, a portion having a large mass at the time of molding has a large shrinkage deformation at the time of cooling, and the roundness may be deteriorated. The same situation may occur when the pressure holding time after injection is not sufficient. However, in the present embodiment, the rib 10 is reduced in size by reducing the mass of the rib 10 by forming the outer-diameter-side protruding end-surface arc portion 14 and the inner-diameter-side protruding end-surface arc portion 16 on the protruding end surface 10s. By setting the thickness T in the axial direction of the connecting portion 8 to be larger than the thickness W in the circumferential direction of 10, the time until the gate is closed can be extended. Therefore, it is possible to slightly stop the contraction deformation at the time of cooling in the entire pulley 2, and it is possible to effectively suppress deterioration in roundness after molding.

  As described above, according to the pulley 2 according to the present embodiment, even when the offset load as described above is applied while reducing the weight, the stress concentration on the offset load is avoided, The stress can be reliably relieved throughout the pulley 2. That is, the pulley 2 can be reduced in size and weight and improved in strength (improvement in durability) at the same time.

  Here, the setting of the curvature radius R1 of the outer-diameter-side projecting end surface arc portion 14 and the curvature radius R2 of the inner-diameter-side projecting end surface arc portion 16 formed on the projecting end surface 10s of the rib 10 is changed, respectively. By configuring the rib 10 in combination with the above, it is possible to avoid stress concentration with respect to the offset load as described above, to surely relieve the stress, and to prevent the pulley 2 from being damaged. It verified by. Hereinafter, the verification result will be described.

  FIG. 3 shows combinations of the set curvature radii R1 and R2 in this test and the verification results of each combination as the presence or absence of damage to the pulley 2. In this test, the curvature radius R1 of the outer-diameter-side protruding end surface arc portion 14 is set to a predetermined value in the range of 5 mm to 12 mm, and the curvature radius R2 of the inner-diameter-side protruding end-surface arc portion 16 is set to 0 mm (inner-diameter side projection Ten subjects a to j (pulleys 2) having ribs 10 set to a predetermined value in a range of 20 mm to 20 mm were prepared. It should be noted that other pulley configurations (material, size (outer diameter side cylindrical portion 4 and the outer diameter side cylindrical portion 4 and the outer radius side protruding cylindrical portion 4) and the radius of curvature R1 of the outer diameter side protruding end surface arc portion 14 and the radius of curvature R2 of the inner diameter side protruding end surface arc portion 16 The outer diameter of the cylindrical portion 6 on the inner diameter side, the thickness, the width, or the number and thickness W of the ribs 10 and the thickness T of the connecting portion 8 are common to each subject (pulley 2). In a state where a predetermined radial load (2000 N) is applied from an endless belt spanning these subjects (pulley 2), each subject (pulley 2) is used at a predetermined speed (common to each subject (pulley 2)). ) For 100 hours, and whether or not damage was confirmed after 100 hours had passed.When applying a predetermined radial load (2000 N) from such a belt, pulley 2 (outer diameter side cylinder) About 10% of the width of the outer circumference of part 4) with respect to the axial direction The belt was adjusted to be offset.

As apparent from FIG. 3, among the subjects a to j, the radius of curvature R1 of the outer-diameter-side projected end surface arc portion 14 is 5 mm, and the radius of curvature R2 of the inner-diameter-side projected end surface arc portion 16 is 0 mm (inner-diameter side projection). Except for the case where the end face arc portion 16 is not formed) (subject a), and when the radius of curvature R1 is set to 4 mm and the radius of curvature R2 is set to 1 mm (subject c). No breakage was observed in any of the subjects (subjects b, d to j). In other words, it was verified that the subjects b and d to j have the effect of avoiding the concentration of stress with respect to the offset load as described above and reliably relaxing the stress.
In addition, when the radius of curvature R1 of the outer-diameter-side protruding end surface arc portion 14 is set to be larger than 14 mm, the outer-diameter-side protruding end surface arc portion 14 becomes closer to a flat surface than the concave curved surface shape (that is, Similarly, when the radius of curvature R2 of the radially projecting end surface arc portion 16 is set to be larger than 20 mm, the inner diameter side projecting end surface arc portion 16 is also substantially flat instead of a concave curved surface shape. Becomes closer to a flat surface than a concave curved surface. For this reason, in any case, it becomes a disadvantageous configuration in order to reduce the size and weight of the rib 10, and as a result, the weight of the pulley 2 is increased, which is not preferable.

  Therefore, based on the verification result, while reducing the weight, even when the offset load as described above is applied, the stress concentration on the offset load is avoided and the stress is surely relieved. In order to maximize the effect, the radius of curvature R1 of the outer-diameter-side projected end surface arc portion 14 is set to 5 mm or more and 14 mm or less, and the radius of curvature R2 of the inner-diameter-side projected end surface arc portion 16 is set to 1 mm or more. The pulley configuration is preferably set to 20 mm or less.

2 Pulley 4 Outer diameter side cylindrical portion 6 Inner diameter side cylindrical portion 8 Connection portion 8s Connection portion peripheral surface portion 10 Rib 10s Rib axially protruding end surface 14 Outer diameter side protruding end surface arc portion 16 Inner diameter side protruding end surface arc portion T Connection portion Axial wall thickness W Rib circumferential wall thickness

Claims (4)

An outer diameter side cylindrical portion for bridging the belt on the outer peripheral surface;
An inner diameter side cylindrical portion arranged concentrically with the outer diameter side cylindrical portion on the inner diameter side of the outer diameter side cylindrical portion;
Extending with a predetermined thickness in the axial direction to the circumferential area between the axial intermediate portion of the inner peripheral surface of the outer diameter side cylindrical portion and the axial intermediate portion of the outer peripheral surface of the inner diameter side cylindrical portion. , An annular connecting portion for connecting the outer diameter side cylindrical portion and the inner diameter side cylindrical portion,
The connecting portion is radially provided on the circumferential surface portions on both sides in the axial direction and protrudes in the axial direction with a predetermined thickness with respect to the circumferential direction, the outer diameter side is the outer diameter side cylindrical portion, and the inner diameter side is the inner diameter side cylindrical portion. And a synthetic resin pulley provided with a plurality of ribs that are respectively coupled to each other,
The rib has an outer diameter side in which a projecting end surface in the axial direction is recessed in the axial direction at a portion where the projecting end surface is continuous with the inner peripheral surface of the outer diameter side cylindrical portion and coupled to the inner peripheral surface of the outer diameter side cylindrical portion. An inner-diameter-side projecting end surface that has a projecting end-surface arc portion and has a portion in which the projecting end surface is continuous with the outer-periphery surface of the inner-diameter-side cylindrical portion that is recessed in the axial direction and coupled to the outer-peripheral surface of the inner-diameter-side cylindrical portion. Having an arc part,
The outer-diameter-side protruding end surface arc portion has a concave arc shape in which the protruding height from the peripheral surface portion of the connecting portion gradually decreases from the outer-diameter end toward the inner-diameter side, and the inner-diameter-side protruding end surface The synthetic resin pulley characterized in that the arc portion has a concave arc shape in which the protruding height from the peripheral surface portion of the connecting portion gradually decreases from the inner diameter end toward the outer diameter side.   The outer diameter side arc portion has a radius of curvature set to 5 mm or more and 14 mm or less, and the inner diameter side arc portion has a curvature radius set to 1 mm or more and 20 mm or less. The synthetic resin pulley according to claim 1.   2. The outer diameter side arc portion and the inner diameter side arc portion are smoothly continuous, and the entire projecting end surface of the rib has a single concave curved surface shape in the axial direction. Or the synthetic resin pulley as described in 2.   The synthetic resin pulley according to any one of claims 1 to 3, wherein a thickness of the connecting portion with respect to an axial direction is set larger than a thickness of the rib with respect to a circumferential direction.

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