JP2011252548A - Bearing with resin pulley, automatic tensioner and resin pulley - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a V-rib of a V-ribbed belt from strongly biting into a V-groove of a pulley and to suppress generation of torque loss caused by frictional resistance accompanying the biting.SOLUTION: A first cylindrical part 6 rotation-symmetric around a pulley shaft is formed at a prescribed position of a tapered surface 4a of the rib 4 of the pulley 2. A groove bottom of a groove formed between the ribs 4, 4 adjacent to each other is made into a buried state by the first cylindrical part 6. When the pulley 2 is provided with the V-ribbed belt 3, the rib 4 bites into the V-groove 5 of the V-ribbed belt 3 by the belt tension, but the first cylindrical part 6 and the V-ribbed belt 3 are made to abut on each other to limit the biting amount. Accordingly, surface pressure generated between the tapered surface 4a of the rib 4 and a tapered surface 5a of the V-groove 5 is reduced according to the biting, thereby suppressing torque loss caused by the surface pressure.

Description

  The present invention relates to a bearing with a resin pulley using a pulley with a rib, and particularly to a bearing using a pulley that does not require a function of torque transmission, such as an idler pulley or a tension pulley.

  The bearing with a resin pulley is obtained by integrally molding a pulley 2 made of resin on an outer ring of a rolling bearing by an injection molding method or the like. This bearing with a resin pulley is used, for example, in a power transmission system around an automobile engine. In this power transmission system, as shown in FIG. 10, power is transmitted to an auxiliary machine such as a crankshaft 12, an alternator 13, an air conditioner 14, and a power steering pump 15 by a belt 3, and a layout of the belt 3 by an idler pulley 16 is provided. Further, the belt tension of the belt 3 is adjusted by the auto tensioner 17.

  The above-described crankshaft 12 or the like is intended for torque transmission. If slippage occurs in the belt driving direction between the pulley such as the crankshaft 12 and the belt 3, the transmission capability is insufficient. Therefore, a pulley having ribs formed on the pulley surface and a V-ribbed belt having V-grooves are generally used for the power transmission system. Then, by causing the rib to bite into the V-groove by belt tension, the taper surfaces of the V-groove and the rib are brought into strong contact with each other, and frictional resistance is generated by the surface pressure (contact pressure). Prevents slipping.

  FIGS. 11 and 12 show how the V-ribbed belt bites into the pulley. The V-ribbed belt 3 approaches each other as the pulley 2 rotates about the axis (see FIG. 12A), and the tapered surface 4a of the rib 4 and the tapered surface 5a of the V-groove 5 come into contact with each other (see FIG. 12). 12 (b)). Furthermore, the belt 2 slides relatively in the radial direction of the pulley 2 so as to be along the tapered surfaces 4a and 5a due to the belt tension, and the rib 4 bites into the V groove 5 to increase the surface pressure between the tapered surfaces 4a and 5a ( (See the arrow in FIG. 12 (c)). This biting depth is determined by various factors such as the shapes of the tapered surfaces 4a and 5a, the belt tension, the material of the V-ribbed belt 3, and the like. The shape of the rib 4 of the pulley 2 and the corresponding V groove 5 of the V-ribbed belt 3 is determined by a standard (JASO E-111-93), and an appropriate combination of the two is selected according to this standard.

  A groove is formed between the ribs 4 of the pulley 2 used in the power transmission system, and stress concentration tends to occur at the bottom of the groove. Further, the substantial thickness of the pulley body is reduced by the depth of the groove. Therefore, for example, in Patent Document 1 below, by increasing the thickness of the rib bottom corresponding to the depth of the groove, the stress concentration and the strength reduction due to the substantial thinning of the pulley main body are prevented and stable. The pulley is driven (see FIG. 1 of the same document).

Japanese Patent No. 4300825

  On the other hand, the pulley 2 used for the idler pulley 16 and the auto tensioner 17 is not intended to transmit torque unlike the crankshaft 12 and the like, and therefore it is not necessary to generate the frictional resistance. In many cases, the same pulley 2 is used.

  In the structure shown in the above-mentioned patent document 1, since the strength of the pulley is secured by increasing the thickness of the rib bottom, the weight of the pulley increases. Further, in the pulley of the type in which the rib is bitten into the V-groove, heat is generated due to friction caused by the surface pressure between the tapered surfaces during the biting. This increase in weight and heat generation cause torque loss in the power transmission system. This torque loss is relatively small in a component intended for torque transmission, such as a crankshaft, compared to the amount of torque transmitted by the crankshaft or the like, and can be almost ignored. On the other hand, a component that does not aim to transmit torque, such as an idler pulley, has a problem in that only a loss occurs even though it does not have its own active action (for example, power generation action by an alternator). is there. This problem is that, although the idler pulley or the like does not require a torque transmission action, it is necessary to generate a high surface pressure by the biting, and the same configuration as the pulley used for the crankshaft or the like is adopted. Is attributed.

  Therefore, the present invention prevents the pulley ribs from strongly biting into the V-grooves of the V-ribbed belt to increase the surface pressure between the tapered surfaces, and this surface pressure causes frictional resistance and torque loss. It is an object to suppress this.

  In order to solve the above problems, the present invention comprises a rolling bearing and a resin pulley integrally formed on the outer ring of the rolling bearing, and the pulley is a pulley of the pulley by belt tension acting on a V-ribbed belt. In a bearing with a resin pulley in which the rib formed on the surface bites into the V groove of the V-ribbed belt and the taper surface of the rib and the taper surface of the V groove generate friction due to surface pressure, thereby transmitting torque. A configuration is adopted in which biting restriction means is provided at a predetermined position of the taper surface to prevent the rib from biting into the V groove of the V-ribbed belt beyond the predetermined position.

  The deeper the rib penetrates into the V-groove, the greater the frictional force between them, and the heat generated by the friction leads to torque loss. Therefore, by providing a biting limiting means for limiting the biting amount of the rib, the frictional force can be prevented from becoming excessive, and the torque loss can be minimized. The “predetermined position” is that if the rib is too rooted, when the rib bites into the V-groove by the belt tension, the V-ribbed belt and the biting restriction means do not come into contact with each other, and the predetermined biting restriction action cannot be exhibited. . For this reason, it is necessary to be at least a position where it abuts on the V-ribbed belt during this biting.

  Further, by providing the biting restriction means, the rib height is substantially lowered, and the depth of the groove between adjacent ribs is reduced. For this reason, it is not necessary to increase the thickness of the rib bottom for the purpose of securing the strength corresponding to the depth of the groove, and the weight of the pulley can be reduced.

  This rib height should be appropriately determined in consideration of the depth of the V groove of the V ribbed belt used for the pulley. A V-groove depth of a general V-ribbed belt that has been used recently is about 2 mm, and considering that the base side of the rib is rounded, the rib height is 3 mm or less. Is preferred.

  Moreover, in the said structure, it is preferable that the said biting restriction | limiting means is a 1st cylindrical part including the said predetermined position and rotationally symmetrical around a pulley axis | shaft.

  When the V-ribbed belt comes into contact with the first cylindrical portion, it is possible to limit the further biting of the V-ribbed belt, so that torque loss due to surface pressure can be suppressed to a minimum.

  Further, in the above configuration, instead of forming the first cylindrical portion, the biting restriction means has a starting point at the predetermined position, and an arc separated from the rib toward the root of the rib is arranged around the pulley axis. It is also preferable that the first rounded portion is formed by rotating the first.

  By forming the first rounded portion in this way, it is possible to limit the biting of the rib into the V groove as in the case of the first cylindrical portion. Further, by causing the tapered surface of the rib and the first rounded portion to be smoothly continuous with each other by an arc, it is possible to prevent stress concentration from occurring at a specific portion of the rib.

  In each of the above structures, it is more preferable that contact avoiding means for preventing the V-ribbed belt and the pulley from contacting each other is provided at a tip position on the tip side of the predetermined position of the rib.

  By providing the contact avoiding means in this manner, the region where the surface pressure is generated by the contact between the rib tip portion and the V-ribbed belt can be narrowed, and torque loss due to the surface pressure can be suppressed to the minimum. it can.

  Moreover, in the structure which provides the said contact restriction means, this contact restriction means has a starting point in the said front-end | tip position, and is toward the front-end | tip part of the said rib from the circular arc formed in the groove bottom of the said V-groove. An arc having a larger radius of curvature is preferably the second rounded portion formed by rotating around the pulley axis.

  When the radius of curvature of the second rounded portion is thus increased, the contact between the second rounded portion and the V-ribbed belt is avoided, and the region where the surface pressure is generated can be narrowed accordingly.

  In the configuration in which the end of the rib of the pulley is rounded, it is more preferable that the radius of curvature of the second rounded portion is 0.5 mm or more.

  The radius of curvature of the rounded portion at the bottom of the V groove of a general V-ribbed belt is smaller than 0.5 mm, and the radius of curvature of the second rounded portion is within the above range (0.5 mm or more). This is because contact between the pulley at the tip and the V-ribbed belt can be reliably avoided.

  Further, instead of the contact limiting means as the second rounded portion, it is preferable that the contact limiting means is a second cylindrical portion including the tip position and rotationally symmetric about the pulley axis.

  By forming the second cylindrical portion in this manner, similarly to the second rounded portion, the region where the surface pressure is generated can be narrowed, and torque loss can be suppressed.

Moreover, in each said structure, it is preferable that the number of the said rib formed in the said pulley is less than the number of the said V groove formed in the said V-ribbed belt.
In this case, since the rib does not bite into a part of the V-groove, the surface pressure can be reduced correspondingly, and the torque loss can be suppressed.

Particularly in the above configuration, it is more preferable that the number of the ribs of the pulley is one or two.
If there are at least one or two ribs, the effect of suppressing torque loss can be further enhanced while preventing troubles in which the V-ribbed belt comes off the pulley surface of the pulley.

Furthermore, in each of the above-described configurations, it is more preferable that gap portions that prevent contact between both ends in the width direction of the V-ribbed belt and the pulleys are formed at both ends in the axial direction of the pulley.
The gap portion may be configured such that both the flange portions of the pulley are separated in the width direction of the pulley to prevent the contact. It may be a gap.

Moreover, it is particularly preferable that the bearing with a resin pulley shown in each of the above-described configurations is used for an auto tensioner.
This auto tensioner is for adjusting the belt tension as described above, and is not intended to transmit rotational torque. For this reason, merits such as suppression of heat generation can be enjoyed by using the bearing with the resin pulley.

  Further, the pulley used for the bearing with the resin pulley can itself reduce torque loss and is not necessarily used in a state of being provided on the outer ring of the bearing.

  According to this invention, friction between the pulley and the V-ribbed belt can be reduced, troubles such as pulley creep due to heat generation can be suppressed, and torque loss can be reduced by reducing the weight of the rib bottom to reduce the weight. For this reason, it is possible to improve the reliability of the bearing with pulley and increase the efficiency of the power transmission system.

Side surface sectional drawing which shows 1st embodiment of the bearing with a resin pulley which concerns on this invention In 1st embodiment, it is side surface sectional drawing which shows the biting of the V ribbed belt to a pulley, (a) is the state which both contact | abutted, (b) is the state which both just contact | abutted, (c) is V Ribbed belt biting into the pulley and contacting the cylinder It is side surface sectional drawing which shows 2nd embodiment of the bearing with a resin pulley which concerns on this invention, Comprising: (a) is a pulley single-piece | unit, (b) is the state where the V-ribbed belt digged into the pulley It is side surface sectional drawing which shows 3rd embodiment of the bearing with a resin pulley which concerns on this invention, Comprising: (a) is a pulley single-piece | unit, (b) is the state which V-ribbed belt digged into the pulley It is side surface sectional drawing which shows 4th embodiment of the bearing with a resin pulley which concerns on this invention, Comprising: (a) is a pulley single-piece | unit, (b) is the state which V-ribbed belt digged into the pulley It is side surface sectional drawing which shows 5th embodiment of the bearing with the resin pulley which concerns on this invention, Comprising: (a) is a pulley single-piece | unit, (b) is the state which V-ribbed belt digged into the pulley It is side surface sectional drawing which shows 6th embodiment of the bearing with the resin pulley which concerns on this invention, Comprising: (a) is a pulley single-piece | unit, (b) is the state which V-ribbed belt digged into the pulley It is side surface sectional drawing which shows 7th embodiment of the bearing with a resin pulley which concerns on this invention, Comprising: (a) formed the 1st cylindrical part, (b) is the 1st cylindrical part and the 2nd cylindrical part. What was formed, (c) is what formed the 1st cylindrical part and the 2nd rounding part In the bearing with pulley shown in FIG. 8, both flanges are omitted, (a) forming the first cylindrical part, (b) forming the first cylindrical part and the second cylindrical part, (C) is formed with a first cylindrical portion and a second rounded portion. Front view showing a general engine power transmission system using pulleys Side surface sectional view which shows embodiment of the bearing with a resin pulley which concerns on a prior art In the embodiment according to the prior art, (a) is a state before both abutment, (b) is a state where both are just abutting, (c) is a state where the V-ribbed belt bites into the pulley

  A first embodiment of a bearing with a resin pulley according to the present invention is shown in FIG. This bearing with a resin pulley is composed of a rolling bearing and a resin pulley 2 formed integrally with the outer ring 1 of the rolling bearing. The pulley 2 is formed by the belt tension acting on the V-ribbed belt 3. The rib 4 formed on the pulley surface bites into the V groove 5 of the V-ribbed belt 3 and the taper surface 4a of the rib 4 and the taper surface 5a of the V groove 5 generate friction due to surface pressure so that torque is transmitted. It is a thing. A first cylindrical portion 6 that is rotationally symmetric about the pulley axis is formed at a predetermined position on the tapered surface 4 a of the rib 4, and is formed between the adjacent ribs 4, 4 by the first cylindrical portion 6. The bottom of the groove is filled. Further, flanges 7 are formed at both ends in the axial direction of the pulley 2, and both the flanges 7, 7 are in contact with both ends in the width direction of the V-ribbed belt 3. In addition, in the same figure, description of a rolling element, an inner ring, etc. is abbreviate | omitted.

  If the “predetermined position” is too close to the base of the rib, the V-ribbed belt 3 and the first cylindrical portion 6 do not come into contact with each other during the biting process of the V-ribbed belt 3, and the biting restriction function cannot be exhibited. For this reason, it is necessary to set the predetermined position so that at least the contact can occur.

  FIG. 2 shows how the V-ribbed belt 3 bites into the pulley 2 in the first embodiment. The V-ribbed belt 3 approaches each other as the pulley 2 rotates about the axis (see FIG. 4A), and the tapered surface 4a of the rib 4 and the tapered surface 5a of the V-groove 5 abut each other (same as above). (See Figure (b)). Further, due to the belt tension, the taper surfaces 4a and 5a are in contact with each other while relatively sliding (approaching), and the rib 4 bites into the V groove 5. At this time, the V-ribbed belt 3 comes into contact with the first cylindrical portion 6 and the biting beyond a predetermined position is restricted. For this reason, the magnitude | size of surface pressure is suppressed compared with the case where this 1st cylindrical part 6 is not provided (the diagonal direction arrow in the same figure (c), and the diagonal direction in FIG.12 (c)). Compare the length of each arrow.

  By limiting the amount of biting in this way, it is possible to reduce friction caused by the surface pressure between the tapered surfaces 4a and 5a accompanying the slide, and to suppress torque loss due to heat generation. In this configuration, in addition to contact between the tapered surfaces 4a and 5a, contact between the tip of the V-ribbed belt 3 and the first cylindrical portion 6 also occurs (see the downward arrow in FIG. 2C). In this contact, only the pressing pressure of the V-ribbed belt 3 against the first cylindrical portion 6 acts, and no relative sliding occurs, so no heat is generated and no torque loss occurs.

  Further, the first cylindrical portion 6 fills the groove bottom between the adjacent ribs 4 and 4, and the groove depth is reduced accordingly. For this reason, it is not necessary to increase the rib bottom thickness t in accordance with the depth of the groove, and the rib bottom of the pulley 2 is thinned (see the two-dot chain line portion in FIG. 1) to reduce its weight. Can be achieved. Thus, if the pulley 2 is reduced in weight, torque loss accompanying the rotation can be suppressed.

  3A and 3B show a second embodiment of the bearing with a resin pulley according to the present invention. In the following embodiment, the outer ring 1 is omitted, and only the pulley 2 and the V-ribbed belt 3 are illustrated and described.

  In this configuration, a first rounding portion 8 is formed that has a starting point at a predetermined position of the rib 4 of the pulley 2 and rotates an arc that moves away from the rib 4 around the pulley axis toward the base of the rib 4. (See FIG. 3A). In the process of biting, when the V-ribbed belt 3 comes into contact with the inner surface (arc) of the first rounded portion 8, the biting beyond the predetermined position of the V-ribbed belt 3 is restricted. According to this configuration, the surface pressure associated with biting can be reduced as in the configuration according to the first embodiment (see the arrow in FIG. 3B). For this reason, it is possible to suppress the generation of friction due to friction and the generation of torque loss due to this surface pressure.

  The first cylindrical portion 6 and the first rounding portion 8 described above are an example of a biting restriction unit, and may have other shapes as long as the same restriction function is exhibited.

  A third embodiment of the bearing with a resin pulley according to the present invention is shown in FIGS. 4 (a) and 4 (b). In this configuration, in the configuration of the second embodiment, the tip end portion of the rib 4 includes the tip position on the tip side of the predetermined position of the rib 4 and the second cylindrical portion 9 that is rotationally symmetric around the pulley axis is formed. It is a thing. When the second cylindrical portion 9 is formed in this way, the contact area (area where the surface pressure is generated) between the rib 4 and the V-ribbed belt 3 can be narrowed, as shown by the broken line arrow in FIG. Torque loss can be suppressed by that amount.

  4th embodiment of the bearing with a resin pulley which concerns on this invention is shown to Fig.5 (a) and (b). In this configuration, in the configuration of the third embodiment, the first rounding portion 8 is changed to the first cylindrical portion 6, and the V by the first cylindrical portion 6 is the same as the configuration of the third embodiment. The action of preventing the bite belt 3 from biting and the action of avoiding the contact between the rib 4 and the V-ribbed belt 3 by the second cylindrical portion 9 are exhibited.

  A fifth embodiment of a bearing with a resin pulley according to the present invention is shown in FIGS. In this configuration, the second cylindrical portion 9 is changed to the second rounding portion 10 in the configuration of the third embodiment, and the V by the first rounding portion 8 is the same as the configuration of the third embodiment. The action of preventing the bite belt 3 from biting and the action of avoiding the contact between the rib 4 and the V-ribbed belt 3 by the second rounded portion 10 are exhibited.

  FIGS. 7A and 7B show a sixth embodiment of the bearing with a resin pulley according to the present invention. In this configuration, the second cylindrical portion 9 is replaced by a second rounded portion 10 in the configuration of the fourth embodiment. Similarly to the fourth embodiment, the V-ribbed belt 3 by the first cylindrical portion 6 is used. And the contact avoidance action between the rib 4 and the V-ribbed belt 3 by the second rounded portion 10 is exhibited.

  FIG. 8 shows a seventh embodiment of the bearing with a resin pulley according to the present invention. In the configuration according to this embodiment, the two ribs 4 of the pulley 2 bite into the V-ribbed belt 3. Thus, by reducing the number of ribs 4 as compared with the first to sixth embodiments, it is possible to avoid the rib 4 of the pulley 2 from biting into a part of the V groove 5 of the V-ribbed belt 3. For this reason, surface pressure can be reduced and torque loss can be suppressed.

  In the seventh embodiment, as shown in FIG. 9, the gap portion 11 may be provided by omitting the flange portion 7 of the pulley 2. If it does in this way, the contact with the width direction both ends of the pulley 2 and the V-ribbed belt 3 can be prevented, and the surface pressure generation resulting from this contact can be prevented. For this reason, torque loss can be further reduced. It is not always necessary to omit the flange portion 7 to form the gap portion 11, and the flange portions 7 formed at both ends in the width direction of the pulley 2 may be separated in the width direction to prevent the contact. Good.

  Since the bearing with a resin pulley shown in each of the above embodiments has a small torque loss due to a reduction in the surface pressure, it is excellent in application to applications where torque transmission is not intended, such as a tension pulley and an idler pulley.

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Pulley 3 V-ribbed belt 4 (Pulley) rib 4a (Rib) taper surface 5 V groove 5a (V groove) taper surface 6 First cylindrical portion (biting-in limiting means)
7 ridge part 8 first rounding part (breaking-in restriction means)
9 Second cylindrical part (contact avoiding means)
10 Second rounding part (contact avoiding means)
11 Clearance

Claims (12)

It comprises a rolling bearing and a resin pulley (2) formed integrally with the outer ring (1) of the rolling bearing. The pulley (2) is driven by the belt tension acting on the V-ribbed belt (3). 2) The rib (4) formed on the pulley surface is formed in the V groove (5) of the V-ribbed belt (3), and the tapered surface (4a) of the rib (4) and the tapered surface (5a) of the V groove (5). In a bearing with a resin pulley that bites in while generating friction due to surface pressure, and that transmits torque,
The rib (4) prevents the rib (4) from biting into the V groove (5) of the V-ribbed belt (3) beyond the predetermined position at a predetermined position of the tapered surface (4a) of the rib (4). A bearing with a resin pulley provided with a biting restriction means (6, 8).   The bearing with a resin pulley according to claim 1, wherein the biting restriction means (6, 8) is a first cylindrical portion (6) including the predetermined position and rotationally symmetric about a pulley axis.   The biting restriction means (6, 8) is formed by rotating an arc having a starting point at the predetermined position and moving away from the rib (4) toward the root of the rib (4) around the pulley axis. The bearing with a resin pulley according to claim 1, wherein the bearing is a first rounded portion (8).   Contact avoiding means (9, 10) for preventing the V-ribbed belt (3) and the pulley (2) from contacting each other at a tip position closer to the tip than the predetermined position of the rib (4) is provided. The bearing with a resin pulley according to any one of claims 1 to 3, wherein the bearing has a resin pulley.   The contact limiting means (9, 10) has a starting point at the tip position, and is larger than an arc formed at the groove bottom of the V groove (5) toward the tip of the rib (4). The bearing with a resin pulley according to claim 4, wherein the bearing is a second rounded portion (10) formed by rotating an arc having a radius of curvature around the pulley axis.   The bearing with a resin pulley according to claim 5, wherein a radius of curvature of the second rounded portion (10) is 0.5 mm or more.   The bearing with a resin pulley according to claim 4, wherein the contact limiting means (9, 10) is a second cylindrical portion (9) including the tip position and rotationally symmetric about a pulley axis.   The number of the ribs (4) formed on the pulley (2) is smaller than the number of the V-grooves (5) formed on the V-ribbed belt (3). The bearing with a resin pulley as described in one.   The bearing with a resin pulley according to claim 8, wherein the number of the ribs (4) of the resin pulley (2) is one or two.   A gap (11) for preventing contact between the both ends in the width direction of the V-ribbed belt (3) and the pulley (2) is formed at both ends in the axial direction of the pulley (2). The bearing with a resin pulley according to any one of 9.   The auto tensioner using the bearing with a resin pulley as described in any one of Claims 1 thru | or 10.   The resin pulley used for the bearing with a resin pulley as described in any one of Claims 1 thru | or 10.

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