JP2009041617A - Resin pulley - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously achieve improvement of fatigue resistance and reduction of weight in a resin pulley having a winding part and a support part. <P>SOLUTION: A radius of curvature R1 of the axial cross section in a bottom part of a circumferential groove 35a positioned on a width direction center side is set to be larger than radiuses of curvature R2 and R3 of the axial cross section in a bottom part of circumferential grooves 35b and 35c separated to the width direction from the circumferential groove in a range where a V-ribbed belt 4 and the bottom part of the circumferential grooves 35a-35c do not interfere with each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin pulley used for engine parts and the like of automobiles.

  In recent years, resin pulleys are used in place of metal pulleys as pulleys used for rotational drive of automobile engine accessories, etc., because of demands for reduction in size and weight and cost. Such a resin pulley has a winding portion having a predetermined width in the axial direction and formed with a circumferential groove around which a V-ribbed belt is wound, and a radially inner portion from the center in the width direction of the winding portion. And a narrow support portion extending in the direction (see, for example, Patent Document 1).

JP 2004-60721 A

  According to the above-described resin pulley, when the V-ribbed belt is hung on the winding portion, both side portions of the winding portion that are not supported by the support portion bend toward the inside in the radial direction around the support portion. It will be. As described above, when both side portions of the winding portion bend inward in the radial direction around the support portion, stress is applied to the bottom portion of the circumferential groove of the winding portion portion at the center in the width direction supported by the support portion. Concentration may occur and fatigue resistance may be reduced.

  Accordingly, an object of the present invention is to improve fatigue resistance in a resin pulley provided with the winding portion and the support portion.

  In order to achieve this object, the first characteristic configuration of the resin pulley according to the present invention includes a winding portion around which a V-ribbed belt for transmitting power is wound, and a radially inward direction from the center in the width direction of the winding portion. A plurality of circumferential grooves that extend along the width direction and engage with projections formed on the V-ribbed belt. In the pulley made of resin, the radius of curvature of the axial cross section at the bottom of the circumferential groove located on the center side in the width direction is within a range in which the V-ribbed belt and the bottom of the circumferential groove do not interfere with each other. The radius of curvature is set to be larger than the radius of curvature of the axial cross section at the bottom of the circumferential groove spaced in the width direction.

  According to the above configuration, the radius of curvature of the axial cross section at the bottom of the circumferential groove located on the center side in the width direction is within the range in which the V-ribbed belt and the bottom of the circumferential groove do not interfere with each other. Is set larger than the radius of curvature of the axial cross section at the bottom of the circumferential groove spaced apart in the width direction, the stress concentration on the bottom of the circumferential groove on the center side is alleviated. For this reason, generation | occurrence | production of the crack in the bottom part of the circumferential direction groove | channel on a center side is suppressed, and the fatigue resistance of a resin pulley improves.

In order to achieve this object, the second characteristic configuration of the resin pulley of the present invention is that the radius of curvature of the axial cross section at the bottom of the circumferential groove is gradually expanded from both ends of the winding portion toward the center. There is in point.
Since the stress applied to the winding portion from the V-ribbed belt wound around the winding portion increases from both ends of the winding portion to the center, the radius of curvature of the axial cross section at the bottom of the circumferential groove is accordingly adjusted. The stress concentration can be more effectively reduced by gradually expanding from both ends of the winding portion toward the center.

  According to the present invention, fatigue resistance can be improved in the resin pulley provided with the winding portion and the support portion.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view of a resin pulley showing a first embodiment of the present invention.
The resin pulley 1 in this embodiment includes a bearing 2 and a resin pulley body 3. The bearing 2 includes an annular inner ring 21, an annular outer ring 22, a plurality of steel balls 23 that are rotatably arranged between the inner ring 21 and the outer ring 22, and these balls 23 are arranged in the circumferential direction. It is a radial ball bearing having a cage 24 held at an equidistant position and seal members 25a and 25b for sealing an annular space between the outer ring 22 and the inner ring 21 on both sides in the axial direction.

  The pulley body 3 has a winding portion 32 around which the V-ribbed belt 4 for transmitting power is wound, and a support that extends radially inward from the center in the width direction of the winding portion 32 and has a smaller width than the winding portion 32. A portion 33 and a cylindrical boss portion 31 formed continuously on the inner peripheral side of the support portion 33 and integrated with the outer peripheral surface of the bearing 2.

As shown in FIG. 2, rising walls 34 are formed on both sides in the width direction of the outer peripheral portion of the winding portion 32, and an odd number along the circumferential direction as a circumferential groove between the rising walls 34 (this In the figure, 5) V-shaped grooves 35a to 35c are provided. Each of these V-shaped grooves 35 a to 35 c is spaced apart in the width direction of the winding portion 32 by interposing protrusions 36 a and 36 b that protrude radially outward and circulate in the circumferential direction.
As shown in FIG. 1, V-shaped ridges 41a to 41c as protrusions formed on the inner peripheral surface of the V-ribbed belt 4 mesh with the ridges 36a and 36b, respectively. When the V-ribbed belt 4 is wound around the winding portion 32 of the pulley body 3 and the V-ribbed belt 4 is rotated, the pulley body 3 is rotated around the central axis P by the bearing 2 along with this operation.

  As the resin material of the pulley body 3, a resin composition in which a fibrous reinforcing material such as glass fiber is contained in a highly insulating phenolic resin, or a fibrous reinforcing material is contained in a resin base material made of a polyamide resin. A resin composition, a resin composition obtained by adding a fibrous reinforcing material to polyphenylene sulfide (PPS), or the like is used.

The pulley body 3 assumes that a commercially available (standard product) V-ribbed belt 4 is used, and without changing the pitch of the V-shaped grooves 35a to 35c in the width direction of the winding portion 32, the pulley body 3 V-shaped grooves 35a to 35c are formed. In this way, when designing the mold of the present invention based on the conventional mold, the number of changes is reduced.
Further, from the viewpoint of preventing the stress received by the V-shaped grooves 35a to 35c from the V-shaped ridges 41a to 41c of the V-ribbed belt 4 as much as possible, as shown in FIG. The oblique side surface S of each V-shaped groove 35a-35c in contact with the V-shaped ridges 41a-41c in the range d from the tip (point intersecting with the alternate long and short dash line E1) to the base (point intersecting with the alternate long and short dash line F1). All degrees are equal. The inclination is not particularly limited, but is preferably set to 40 ° ± 1 ° as defined by the Japan Society for Automotive Engineers (JASO E-111-93).

FIG. 3 is an enlarged view of the V-shaped grooves 35a to 35c of the winding portion 32 shown in FIG. In the resin pulley 1 according to this embodiment, the bottom portions B1 to B3 of the V-shaped grooves 35a to 35c are formed by arcs having curvature radii R1 to R3, respectively. The straight lines forming the side surfaces S of the V-shaped grooves 35a to 35c are tangent to these arcs, and the bottoms B1 to B3 of the V-shaped grooves 35a to 35c form the arcs and the side surfaces S of the curvature radii R1 to R3. The straight line is smoothly connected without having a corner.
The resin pulley 1 is formed by gradually increasing the diameters of the bottoms B1 to B3 of the V-shaped grooves from the V-shaped grooves 35a to the bottoms B1 to B3 of the V-shaped grooves 35b and 35c (D1>D2> D3). The curvature of the axial cross section at the bottom B1 of one V-shaped groove 35a located at the axial center of the pulley body 3 without changing the pitch of each V-shaped groove 35a to 35c and the slope of the side surface S. The radius of curvature R2, R3 of the axial cross section at the bottoms B2, B3 of the V-shaped grooves 35b, 35c on the side spaced apart in the width direction from the V-shaped groove 35a located at the center of the pulley body 3 is the largest. (R1>R2> R3). In this way, the stress concentration at the bottom B1 of the V-shaped groove 35a corresponds to the stress against the load from the V-ribbed belt that increases from the rising wall 34 side of the winding portion 32 toward the support portion 33. Alleviated. The radius of curvature R2 of the axial cross section at the bottom B2 of the V-shaped groove 35b that receives the next largest stress after the V-shaped groove 35a is smaller than the radius of curvature R1 of the axial cross-section at the bottom B1 of the V-shaped groove 35a. Since the radius of curvature R3 of the axial cross section at the bottom B3 of the groove 35c is larger than that of the bottom B3 of the V-shaped groove 35c, the stress concentration is relaxed. In this way, since the bias of stress distribution in the axial direction of the winding portion 32 can be corrected without increasing the thickness of the winding portion 32, the stress concentration in the winding portion 32 is effectively relieved and fatigue resistance is improved. Can be improved.

  However, since the V-shaped grooves 35a to 35c and the V-ribbed belt 4 may interfere with each other if the curvature radii R1 to R3 of the axial cross sections at the bottoms B1 to B3 of the V-shaped grooves 35a to 35c are too large, this interference may occur. It is necessary to set the curvature radii R1 to R3 of the axial cross-sections at the bottoms B1 to B3 of the V-shaped grooves 35a to 35c within a range in which V can be avoided. Conventionally, in order to avoid the interference between them, it is considered preferable that the radius of curvature of the axial section of the V-shaped groove is 0.5 mm or less. Therefore, in the resin pulley 1 according to the present invention, it is allowed to set the curvature radius of the axial cross section at the bottoms B1 to B3 of the V-shaped grooves 35a to 35c to 0.5 mm or more. The curvature radius R2 of the cross section in the axial direction at the bottom B2 of the V-shaped groove 35b adjacent to the outside in the axial direction of the V-shaped groove 35a can be set in a range not exceeding the curvature radius R1. Further, the curvature radius R3 of the axial cross section at the bottom B3 of the V-shaped groove 35c adjacent to the outside in the axial direction of the V-shaped groove 35b can be set within a range equal to or not exceeding the curvature radius R2.

FIG.4 and FIG.5 is an expanded sectional view of the winding part 32 in the resin pulley 1 which is 2nd Embodiment of this invention. Also in this embodiment, as in the first embodiment, the pitch of the V-shaped grooves 35a to 35c and the V-shaped grooves 35a to 35c in the range d from the distal end portion to the base side of the convex strips 36a to 36c. The slopes of the side surfaces S are all the same. In addition, in each of the V-shaped grooves 35a to 35c, a range where an arc having the curvature radii R1 to R3 is formed is defined as bottoms B1 to B3. However, in this embodiment, unlike the first embodiment, the diameters D1 to D3 of the bottom portions B1 to B3 of the V-shaped grooves 35a to 35c are made equal (D1 = D2 = D3). For this reason, when these curvature radii are gradually decreased from the axial center side toward the outside (R1>R2> R3), the lines extending from the side surfaces S of the V-shaped grooves 35a to 35c are arcs having the curvature radii R1 to R3. It is not tangent. For this reason, the axial cross sections of the bottom portions B1 to B3 of the V-shaped grooves 35a to 35c are arcs of curvature radii R1 to R3 in the range of the widths W1 to W3, but these arcs and the V-shaped grooves 35a to 35c Connection portions C1 to C3 that are not an extension line of the side surface S but a curved line different from the arcs of the curvature radii R1 to R3 are provided between the side surfaces S, and these are smoothly connected without corner portions. In this embodiment, since the shapes of the connecting portions C1 to C3 are set so that the arcs of the curvature radii R1 to R3 can be widened in the respective V-shaped grooves 3a to 35c, the curvature radius of the bottom portion is set. The width becomes longer as W is smaller (W3>W2> W1).
In the resin pulley 1 described above, the imaginary line connecting the bottom portions B1 to B3 of the V-shaped grooves 35a to 35c is a straight line parallel to the central axis P (see FIG. 1) of the pulley body 3 in the axial section. If it does in this way, since the thickness of the part located in the center side of the said support part 33 of the said winding part 32 does not increase, it can reduce in weight that much.

  Further, the third embodiment of the present invention shown in FIG. 6 is a resin pulley in which the number of V-shaped grooves of the resin pulley 1 of the first embodiment shown in FIGS. 1 to 3 is changed to an even number (six in this figure). 1. In this embodiment, as in the first embodiment, the pitch of each V-shaped groove 35a to 35c and the side surface of each V-shaped groove 35a to 35c in the range d from the distal end portion to the base side of each protruding line 36a to 36c. The slopes of S are all the same, and the radii of curvature R1 to R3 are set to be the same as those in the first embodiment. In this case, in order to relieve stress concentration on the two V-shaped grooves 35a located on the extension side of the support portion 33 (center of the winding portion 32) and on the center side of the winding portion 32, the two V-shaped grooves 35a The curvature radii R1 to R3 of the axial cross section at the bottoms B1 to B3 of the V-shaped grooves 35a to 35c are set so that the curvature radius R1 of the axial cross section at the bottom B1 is maximized (R1> R2> 3). . In this way, the radii of curvature R1 to R3 of the axial cross sections at the bottoms B1 to B3 of the V-shaped grooves 35a to 35c are set symmetrically in the axial direction of the resin pulley 1, so that the winding part 32 and the support part The bias of the stress distribution 33 is relaxed in line symmetry with the axial direction as the center, and the unbalance of the stress distribution in the axial direction is suppressed.

  Moreover, in each said embodiment, although V-shaped groove | channels 35a-35c demonstrated in the case of five pieces or six pieces, the number of V-shaped grooves 35a-35c of the resin pulley 1 which concerns on this invention is limited to this. It is not a thing, and it can be considered more or less. In any case, compared with the radius of curvature R1 of the cross section in the axial direction at the bottom B1 of the center-side V-shaped groove 35a, at the bottoms B2 and B3 of the V-shaped grooves 35b and 35c located on the outer side in the width direction of the V-shaped groove 35a. By reducing the radii of curvature R2 and R3 of the axial section, the effect of relaxing stress concentration on the bottom B1 of the V-shaped groove 35a at the center in the width direction of the winding portion 32 is the same as in the above embodiments. Can be played. Therefore, for example, only the radius of curvature R1 of the axial cross section at the bottom B1 of the central V-shaped groove 35a is used, and the radius of curvature of the axial cross section of the bottom B2 and B3 of the other V-shaped grooves 35b and 35c positioned on the outer side in the width direction. It can also be made larger than R2 and R3 (R1> R2 = R3). Thus, in setting the radius of curvature R1 to R3 of the axial cross section at the bottom B1 to B3 of the V-shaped grooves 35a to 35c, the diameter D1 of the bottom B1 of the V-shaped groove 35a is set to the bottom B2 of the V-shaped grooves 35b and 35c. It is made longer than the diameters D2 and D3 of B3 (D1> D2 = D3), and only the curvature radius R1 of the axial cross section at the bottom B1 of the V-shaped groove 35a is set at the bottoms B2 and B3 of the V-shaped grooves 35b and 35c. It is larger than the curvature radii R2 and R3 of the axial cross section. In addition, without changing the diameters D1 to D3 of the bottom portions B1 to B3 of the V-shaped grooves 35a to 35c (D1 = D2 = D3), the curvature radius R1 of the arc formed on the bottom portion B1 of the V-shaped groove 35a is changed to the V shape. You may make larger than the curvature radius R2 of the circular arc formed in bottom part B2, B3 of groove | channel 35b, 35c.

  Incidentally, without changing the diameters D1 to D3 of the bottom portions B1 to B3 of the V-shaped grooves 35a to 35c (D1 = D2 = D3), a line extending the side surface S of the V-shaped grooves 35a and 35b and a bulge to the outside of the line. The curvature radius of the cross section in the axial direction at the bottoms B1 to B3 of the V-shaped grooves 35a to 35c can also be gradually reduced by connecting the extracted arcs (R1> R2> R3). However, when such a shape is used, corner portions are formed at the connection portions between the side surfaces S of the V-shaped grooves 35a to 35c and the arcs, so that stress is easily concentrated on the corner portions and is difficult to be molded. Therefore, the bottom portions B1 to B3 of the V-shaped grooves 35a to 35c are configured so that the side surface S and the bottom portions B1 to B3 are smoothly continuous without providing corners as in the first to third embodiments described above. preferable.

In any of the above-described embodiments, the length of the side surface S of each V-shaped groove 35a to 35c that comes into contact with the V-shaped ridges 41a to 41c is the same as the V-shaped ridges 41a to 41c of the V-ribbed belt 4. Since it changes according to the shape of the V-shaped grooves 35a to 35c, it is appropriately changed according to the use situation.
In the second embodiment, the widths W1 to W3 of the bottom portions B1 to B3 of the V-shaped grooves 35a to 35c effectively relieve stress concentration at the bottom portions B1 and B2 of the V-shaped grooves 35a and 35b on the axial center side. And it changes suitably and implements in the range which can eliminate the imbalance of the stress distribution in bottom part B1-B3 of V-shaped groove 35a-35c. This range can be obtained by stress analysis or experiment.

It is sectional drawing of the resin pulleys concerning this invention. It is an expanded sectional view of the winding part of the resin pulley which concerns on 1st Embodiment of this invention. It is an expanded sectional view of the winding part of the resin pulley shown in FIG. It is an expanded sectional view of the winding part of the resin pulley which concerns on 2nd Embodiment of this invention. It is an expanded sectional view of the winding part of the resin pulley shown in FIG. It is an expanded sectional view of the winding part of the resin pulley which concerns on 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin pulley 2 Bearing 3 Pulley main body 32 Winding part 33 Support part 35a-35c V-shaped groove | channel (circumferential groove)
4 V-ribbed belts 41a to 41c V-shaped ridges (protrusions)
B1-B3 V-shaped groove bottom R1-R3 radius of curvature

Claims (2)

A winding part for winding a V-ribbed belt for transmitting power, and a support part extending inward in the radial direction from the center in the width direction of the winding part and having a smaller width than the winding part,
In the resin pulley in which a plurality of circumferential grooves in which the protrusions formed on the V-ribbed belt mesh with the outer peripheral portion of the winding portion are arranged in parallel in the width direction,
As long as the V-ribbed belt and the bottom of the circumferential groove do not interfere with each other, the radius of curvature of the axial cross section at the bottom of the circumferential groove located on the center side in the width direction is separated from the circumferential groove in the width direction. A resin pulley characterized in that it is set larger than the radius of curvature of the axial cross section at the bottom of the circumferential groove.   The resin pulley according to claim 1, wherein the radius of curvature of the axial cross section at the bottom of the circumferential groove is gradually enlarged from both ends of the winding portion toward the center.

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