JP2004239381A - Resin pulley - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin pulley which is high in transmission efficiency of the driving force even when the tension of a stretched V-ribbed belt is small, and capable of preventing degradation of the service life of the belt. <P>SOLUTION: A large number of projections 5a are circumferentially formed in side face 1w of a V-groove 1v formed in an outer circumferential surface 1x of an outer cylindrical part 1. The projections 5a form resistance against slip, and prevent small slip between the belt and the V-groove 1v. Therefore, in the resin pulley, slip between the V-ribbed belt and the V-groove attributable to the fluctuation in the angular velocity of an engine crank shaft is suppressed without setting the belt tension to be higher, and the torque can be reliably transmitted. Further, by setting the belt tension to be lower, degradation of the service life of the belt itself can be prevented. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a synthetic resin pulley used for a power transmission mechanism with an endless belt stretched over, for example, a driven pulley attached to a rotating shaft of accessories in an automobile engine.
[0002]
[Prior art]
The camshafts and accessories of the vehicle engine are a V-ribbed belt between a drive pulley fixed to the end of the crankshaft of the engine and a driven pulley fixed to the end of the rotating shaft of these camshafts and accessories. (Endless belt), and is rotationally driven by power transmission by traveling of the belt.
[0003]
Since the engine generates driving energy only during the explosion process and does not exert a driving force in other processes, the crankshaft as a driving source of the engine constantly has a slight variation in angular velocity during its rotation. For this reason, a means for increasing the inertia force by attaching a flywheel or the like to the crankshaft of a normal engine to approximate smooth running is adopted. However, even with this means, it is difficult to completely suppress the angular speed fluctuation of the crankshaft, and the angular speed fluctuation of about 1.5 to 2.0 degrees at maximum in a gasoline engine and about 6 to 8 degrees in a diesel engine occurs. I will. At the same time, the speed of the endless belt stretched between the pulleys also fluctuates.
[0004]
On the other hand, since auxiliary equipment such as an alternator provided in the engine is more efficient to drive at a constant speed, the rotation axis of the auxiliary equipment and this rotation Angular velocity fluctuation absorbing means such as a one-way clutch is provided between the driven pulley supported on the shaft. This angular velocity fluctuation absorbing means transmits the torque of the pulley to the rotating shaft of the accessories when the angular speed of the crankshaft increases, and the rotation of the rotating shaft becomes faster than the pulley due to the inertia of the accessories when the angular speed of the crankshaft decreases. In such a case, the one-way clutch or the like is disengaged, and the rotation of the accessories is set to a substantially constant speed (for example, see Patent Document 1 or Patent Document 2).
[0005]
[Patent Document 1] Japanese Patent Publication No. 7-72585 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-304381
[Problems to be solved by the invention]
By the way, in the above-described resin pulley, since a crankshaft (drive pulley) whose angular velocity fluctuates is used as a drive source, an auxiliary machine such as an alternator that rotates at a substantially constant speed is driven. A slight slip (slip) occurs between a driven pulley provided on a rotating shaft of accessories and a V-ribbed belt (endless belt), and local expansion and contraction occur in the V-ribbed belt before and after the driven pulley. .
[0007]
Further, in the field of automobile engines, improvement of transmission efficiency of a power transmission mechanism using such pulleys has been an issue due to improvement of engine output or dieselization. Therefore, in order to further reduce the slip of the V-ribbed belt due to the angular speed fluctuation of the crankshaft, measures have been taken recently to increase the belt tension between the pulleys.
[0008]
However, in contrast to increasing the tension to prevent slippage, the V-ribbed belt has a problem in that the remaining force (elasticity) corresponding to the above-mentioned local expansion and contraction is reduced and the life is shortened. there were. In addition, increasing the belt tension requires the resin pulley itself to have high rigidity and the like. In addition, rolling bearings, one-way clutches, and the like that are interposed between the pulley and the auxiliary devices are also required. It is necessary to take measures, which may cause an increase in overall costs.
[0009]
The present invention has been made in view of such circumstances, and a resin pulley that does not reduce the life of a V-ribbed belt that does not reduce the life of the belt even if the tension of the V-ribbed belt is low is high. It is intended to provide.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is directed to a resin pulley having a plurality of V-grooves on an outer peripheral surface which engage with a V-ribbed belt traveling in a constant direction while varying in speed. A plurality of discontinuous protrusions are formed on the side surface of the V groove in the circumferential direction.
[0011]
In addition, it is preferable that each of the protrusions has a shape that prevents slippage of the V-ribbed belt when the speed of the V-ribbed belt increases, and allows slippage in the reverse direction of the rotation direction of the belt when the speed of the V-ribbed belt decreases. (Claim 2)
[0012]
The present invention relates to a synthetic resin pulley used for a power transmission mechanism with a V-ribbed belt stretched over, the outer peripheral surface of the pulley serving as an engagement surface with the V-ribbed belt, the side surface of the V-groove (V-rib), and the circumferential direction of the belt. The purpose of the present invention is to achieve the intended purpose by providing a projection for preventing the slippage of the object.
[0013]
That is, according to the first aspect of the present invention, by forming the projection on the side surface of the V-groove on the outer peripheral surface of the resin pulley, slippage between the V-ribbed belt and the V-groove caused by the angular speed variation of the crankshaft is prevented. can do. Further, with this configuration, even if the tension of the V-ribbed belt is not set high, slippage of the V-ribbed belt is prevented, and torque is transmitted reliably. Therefore, the resin pulley of the present invention improves the transmission efficiency of the driving force due to the running of the V-ribbed belt, and can set the tension of the V-ribbed belt to be lower than before, so that the life of the belt itself is not shortened.
[0014]
In addition, by forming the protrusion into a shape in which the V-ribbed belt slips only in the direction opposite to the running direction of the belt, the torque is reliably transmitted and transmitted when the V-ribbed belt is accelerated, similarly to the principle of the one-way clutch. It is possible to improve the efficiency and prevent the V-ribbed belt from being pulled in a direction opposite to the running direction due to a slight slip between the V-ribbed belt and the V-groove at the time of deceleration. Therefore, the resin pulley can reduce the local expansion and contraction of the V-ribbed belt, thereby improving the life of the belt.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an external perspective view showing the structure of a resin pulley according to the first embodiment of the present invention, and FIG. 2 is an enlarged view of a V-groove formed on the outer peripheral surface of the resin pulley.
[0016]
As shown in FIG. 1, this resin pulley has an outer cylindrical portion 1, an inner cylindrical portion 2, and an annular disk for integrally connecting the outer cylindrical portion 1 and the inner cylindrical portion 2 to each other. The portion 3 is formed mainly. Also, a plurality of V-grooves (poly-V-grooves) 1v, 1v,... Which engage with a V-ribbed belt (not shown) which is stretched over the pulley are formed on the outer peripheral surface 1x of the resin-made pulley. , And a plurality of radial reinforcing ribs 4, 4,... Connecting the outer cylindrical portion 1 and the inner cylindrical portion 2 along the radial direction of the pulley on both end surfaces of the annular disk portion 3. Is formed.
[0017]
A one-way clutch for transmitting torque by engaging only in the running direction of the belt is provided between an inner cylindrical portion (boss portion) 2 of the resin pulley and a shaft (not shown) supporting the pulley. , A rolling bearing such as a ball bearing is interposed. Further, the synthetic resin material constituting the resin pulley is not particularly limited, and for example, a polyamide 6 resin, a polyamide 6-6 resin, a phenol resin, a polyacetal resin, or the like can be used. Further, these synthetic resins may be mixed with reinforcing fibers such as glass fibers as necessary.
[0018]
The feature of the resin pulley in the present embodiment is that, as shown in the enlarged view of FIG. 2, both side surfaces 1w of a V-shaped groove 1v formed between a peak portion 1s and a valley portion 1t of the outer cylindrical portion outer peripheral surface 1x. , 1w, a large number of protrusions 5a having a substantially hemispherical cross section are formed in the circumferential direction. In addition, these projections 5a serve as resistance to sliding, and prevent minute sliding between the V-ribbed belt and the V-groove 1v.
[0019]
Therefore, in this resin pulley, the slip between the V-ribbed belt and the V-groove 1v caused by the angular velocity fluctuation of the crankshaft is suppressed without setting the tension of the V-ribbed belt high, so that the torque can be transmitted reliably. become. Further, since the tension of the V-ribbed belt can be set lower than before, the effect of improving the life of the belt itself can also be achieved.
[0020]
Next, a second embodiment of the present invention will be described.
FIG. 3 is an external perspective view showing the structure of a resin pulley according to the second embodiment of the present invention, and FIG. 4 is an enlarged view of a V-groove formed on the outer peripheral surface of the resin pulley. Components having the same functions as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0021]
The difference between the resin pulley according to the second embodiment and the resin pulley according to the first embodiment is the shape of the projection 5b formed on the side surface of the V groove 1v.
As shown in FIG. 4, a large number of the protrusions 5b are formed on both sides 1w, 1w of each V-groove 1v in the circumferential direction, and each of the protrusions 5b has a shape corresponding to the rotational direction of the pulley (that is, the V-ribbed belt). It is formed in a triangular pyramid shape that gradually rises from the side surface of the pulley from the front side to the rear side in the traveling direction). With this shape, when the speed of the V-ribbed belt is increased, the protruding portion formed on the rear side of the protrusion 5b becomes a resistance, and the belt is prevented from slipping. Conversely, when the speed of the V-ribbed belt decreases, the tapered portion on the front side of the protrusion 5b allows the belt to slide in the reverse direction of the belt rotation direction, and alleviates local expansion and contraction of the belt before and after the resin pulley. it can.
[0022]
Therefore, similarly to the first embodiment, the resin pulley according to the present embodiment can also improve the transmission efficiency of the driving force by traveling of the V-ribbed belt without setting the tension of the V-ribbed belt high. In addition, this resin pulley can set the tension of the V-ribbed belt lower than before, and can also alleviate local expansion and contraction of the belt caused by fluctuations in the angular velocity of the crankshaft, thereby extending the life of the V-ribbed belt. The effect can be achieved.
[0023]
In the embodiment described above, one example of the shape of the protrusion formed on the V-groove side surface 1w is shown for each of the example having no direction in the circumferential direction of the pulley and the example having the direction. However, the shape of the projection is not limited to these examples. For example, as a shape example of a directional projection that prevents the belt from slipping when the speed of the belt increases and allows the belt to slip when the speed of the belt decreases, a triangle gradually rising from the side surface of the pulley in the second embodiment. Instead of the conical shape, a trapezoidal projection 5c inclined with respect to the circumferential direction as shown in the enlarged view of FIG. 5 may be formed.
[0024]
【The invention's effect】
As described above in detail, according to the resin pulley of the present invention, the slip between the V-ribbed belt and the V-groove caused by the angular speed variation of the crankshaft of the engine is suppressed without setting the tension of the V-ribbed belt to be high. Thus, torque can be transmitted reliably. Further, since the tension of the V-ribbed belt can be set lower than before, the life of the belt itself can be prevented from being shortened.
[Brief description of the drawings]
FIG. 1 is an external perspective view of a resin pulley according to a first embodiment of the present invention.
FIG. 2 is an enlarged view of a V groove 1v in the resin pulley according to the first embodiment of the present invention.
FIG. 3 is an external perspective view of a resin pulley according to a second embodiment of the present invention.
FIG. 4 is an enlarged view of a V groove 1v in a resin pulley according to a second embodiment of the present invention.
FIG. 5 is an enlarged view showing another shape of a projection formed on a side surface 1w of a V groove 1v in the resin pulley according to the second embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 1 outer cylindrical portion 1s peak portion 1t valley portion 1v V groove 1w V groove side surface 1x outer peripheral surface 2 inner cylindrical portion 2y inner peripheral surface 3 annular disk portion 4 reinforcing ribs 5a, 5b, 5c

Claims (2)

In a resin pulley having a plurality of V-grooves on its outer peripheral surface that engage with a V-ribbed belt traveling in a certain direction while accompanied by speed fluctuation,
A plurality of discontinuous protrusions are formed on a side surface of the V-shaped groove in a circumferential direction. Each of the protrusions is formed in a shape that prevents slippage of the V-ribbed belt when the speed of the V-ribbed belt increases, and allows the belt to slide in a direction opposite to the running direction of the belt when the speed of the V-ribbed belt decreases. The resin pulley according to claim 1, wherein:

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