JP4139962B2 - Resin pulley - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a synthetic resin pulley used in a power transmission mechanism over which an endless belt is stretched, such as a driven pulley attached to a rotating shaft of auxiliary equipment in an automobile engine.
[0002]
[Prior art]
The camshaft and accessories of a vehicle engine are provided with 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 the camshaft and accessories. (Endless belt) is passed over and is driven to rotate by power transmission by running of this belt.
[0003]
Since the engine generates driving energy only during the explosion process and does not exhibit driving force in other processes, the crankshaft as the driving source always undergoes minute fluctuations in angular velocity during its rotation. For this reason, means for increasing the inertial force by attaching a flywheel or the like to a crankshaft in a normal engine so as to approach smooth running is employed. However, even with this means, it is difficult to completely suppress the crankshaft angular velocity fluctuation, and the angular velocity fluctuation of about 1.5 to 2.0 degrees at the maximum in the gasoline engine and about 6 to 8 degrees at the maximum in the diesel engine occurs. End up. At the same time, the speed of the endless belt stretched between the pulleys also varies.
[0004]
On the other hand, since it is more efficient to drive an auxiliary machine such as an alternator provided in the engine at a constant speed, in order to absorb the above-mentioned fluctuation of the angular speed of the crankshaft, the rotation axis of the auxiliary machine and this rotation Between the driven pulley supported by the shaft, angular velocity fluctuation absorbing means such as a one-way clutch is provided. This angular velocity fluctuation absorbing means transmits the torque of the pulley to the rotating shaft of the auxiliary machinery when the angular velocity of the crankshaft increases, and when the angular velocity of the crankshaft decreases, the rotating shaft rotates faster than the pulley due to the inertia of the auxiliary machinery. In such a case, the one-way clutch or the like is disengaged, and the auxiliary machinery is configured to rotate at a substantially constant speed (see, for example, Patent Document 1 or Patent Document 2).
[0005]
[Patent Document 1]
Japanese Patent Publication No. 7-72585 [Patent Document 2]
Japanese Patent Laid-Open No. 2001-304381
[Problems to be solved by the invention]
By the way, in the resin pulleys as described above, in order to drive auxiliary machines such as an alternator that tries to rotate at a substantially constant speed using a crankshaft (drive pulley) whose angular speed fluctuates as a drive source, these pulleys are used. A minute slip occurs between the driven pulley provided on the rotating shaft of the auxiliary machinery and the V-ribbed belt (endless belt), and local expansion and contraction occurs in the V-ribbed belt before and after the driven pulley. .
[0007]
Further, in the field of automobile engines, improvement in transmission efficiency of a power transmission mechanism using such a pulley has been a problem due to improvement in engine output or dieselization. Therefore, in order to further reduce the slip of the V-ribbed belt caused by the fluctuation of the angular velocity of the crankshaft, measures for increasing the belt tension between the pulleys have been taken in recent years.
[0008]
However, the V-ribbed belt has a problem that the remaining force (elasticity) corresponding to the above-described local expansion / contraction is reduced and the life is shortened, contrary to increasing the tension to prevent the slip. there were. In addition, increasing the belt tension requires that the resin pulley itself be highly rigid, as well as rolling bearings, one-way clutches, etc. that are interposed between this pulley and the auxiliary machinery. It is necessary to take a countermeasure, and it becomes a factor of cost increase as a whole.
[0009]
The present invention has been made in view of such circumstances, and a resin pulley that has a high driving force transmission efficiency and does not reduce the life of the belt even when the tension of the V-ribbed belt is low. It is intended to provide.
[0010]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention provides a resin pulley having a plurality of V-grooves engaged with a V-ribbed belt that travels in a fixed direction with speed fluctuations on the outer peripheral surface, and a side surface of each V-groove. in the during the speed increase of the V-ribbed belt to prevent slippage of the belt, the V-ribbed belt of a non-continuous impact of the shape at the time of decreasing the rate to permit sliding in the opposite direction of the running direction of the belt-outs, circumferentially A plurality is formed.
[0011]
[0012]
The present invention relates to a synthetic resin pulley used in a power transmission mechanism that spans a V-ribbed belt, and a circumferential direction of the belt on a side surface of a V-groove (V-rib) on an outer circumferential surface of the pulley that is an engagement surface with the V-ribbed belt. By providing the protrusions that prevent the slippage of the material, the intended purpose is achieved.
[0013]
In other words, according to the first aspect of the present invention , the V-ribbed belt slips only in the direction opposite to the running direction of the belt on the side surface of the V groove on the outer peripheral surface of the resin pulley in a discontinuous shape in the circumferential direction. By forming the protrusions in the shape , similar to the principle of the one-way clutch, when the V-ribbed belt is accelerated, the torque is reliably transmitted to improve the transmission efficiency. When the V-ribbed belt is decelerated, the belt and the V-groove are It is possible to prevent the V-ribbed belt from being pulled in the direction opposite to the traveling direction due to a slight slip therebetween . Also, with this configuration, the V-ribbed belt is prevented from slipping and the torque is reliably transmitted without setting the tension of the V-ribbed belt high. Therefore, the resin pulley of the present invention improves the transmission efficiency of the driving force due to the travel of the V-ribbed belt, and the tension of the V-ribbed belt can be set lower than before, so that the life of the belt itself is not reduced.
[0014]
Moreover, this resin pulley can exert an effect of improving the life of the belt by relaxing locally extending or contracting the V-ribbed belt.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Figure 1 is an external perspective view showing the structure of a resin pulley according to the present onset Ming embodiment, 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, the resin pulley includes an outer cylindrical portion 1, an inner cylindrical portion 2, and an annular disc that integrally connects the outer cylindrical portion 1 and the inner cylindrical portion 2. It is formed mainly of the part 3. A plurality of V grooves (poly V grooves) 1v, 1v,... That engage with a V-ribbed belt (not shown) spanned over the pulley are formed on the outer cylindrical surface 1x of the resin pulley. In addition, 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 are provided on both end faces of the annular disc portion 3. Is formed.
[0017]
A one-way clutch that engages only in the belt traveling direction and transmits torque between an inner cylindrical portion (boss portion) 2 of the resin pulley and a shaft (not shown) that supports the pulley. In addition, rolling bearings such as ball bearings are disposed. Moreover, the synthetic resin material which comprises this resin pulley is not specifically limited, For example, polyamide 6 resin, polyamide 6-6 resin, a phenol resin, or a polyacetal resin etc. can be used. Moreover, you may mix reinforcing fibers, such as glass fiber, with these synthetic resins as needed.
[0018]
As shown in the enlarged view of FIG. 2, the resin pulley according to the present embodiment is characterized in that both side surfaces 1w of the V groove 1v formed between the crest 1s and the trough 1t of the outer cylindrical surface 1x. and 1 w, its individual shape, projections 5 b formed gradually rises triangular pyramid shape from the pulley side from the front toward the rear in the rotational direction (i.e. the direction of travel of the V-ribbed belt) of the pulley, a large number in the circumferential direction It is a point that is formed .
[0019]
[0020]
[0021]
The shape of this, when the rate of increase of V-ribbed belt, projecting portion formed on the rear side of the projections 5b become resistance, slip of the belt is prevented. Conversely, when the speed of the V-ribbed belt is reduced, the taper portion on the front side of the protrusion 5b allows slipping in the reverse direction of the rotation direction of the belt, and the local expansion and contraction of the belt before and after the resin pulley is alleviated. it can.
[0022]
Therefore, the resin pulley in the present embodiment can improve the transmission efficiency of the driving force due to the running of the belt without setting the tension of the V-ribbed belt high. In addition to the fact that the tension of the V-ribbed belt can be set lower than that of the conventional pulley, this resin pulley can alleviate the local expansion and contraction of the belt due to the angular velocity fluctuation of the crankshaft, thereby extending the life of the V-ribbed belt. There is an effect.
[0023]
In the embodiments above, an example of the shape of discontinuous protrusions having a directionality in the circumferential direction of the pulley, has been one shown, the shape of the protrusions is not limited to this example. For example, as an example of a directional protrusion that prevents belt slippage when the belt speed increases and allows belt slippage when the belt speed decreases, a triangular pyramid shape that gradually rises from the pulley side surface in this embodiment. Instead, a trapezoidal protrusion 5c inclined with respect to the circumferential direction as shown in the enlarged view of FIG. 3 may be formed.
[0024]
【The invention's effect】
As described in detail above, according to the resin pulley of the present invention, slippage between the V-ribbed belt and the V-groove caused by the angular speed fluctuation of the crankshaft of the engine is suppressed without setting the tension of the V-ribbed belt high. Thus, torque can be transmitted reliably. Further, since the tension of the V-ribbed belt can be set lower than the conventional one, it is possible to prevent the life of the belt itself from being reduced.
[Brief description of the drawings]
1 is an external perspective view of a resin pulley according to the present onset Ming embodiment.
2 is an enlarged view of the V-groove 1v in the resin pulley of the present onset Ming embodiment.
3 is an enlarged view showing another example of the shape of the projections formed on the side surface 1w of V grooves 1v in the resin-made pulley according to the embodiment of this invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer cylindrical part 1s Mountain part 1t Valley part 1v V groove 1w V groove side surface 1x Outer peripheral surface 2 Inner cylindrical part 2y Inner peripheral surface 3 Annular disk part 4 Reinforcement rib
5 b, 5c projections

Claims (1)

In a resin pulley having a plurality of V grooves on the outer peripheral surface that engage with a V-ribbed belt that travels in a certain direction with speed fluctuation,
Wherein the side of each V-shaped groove, at the time of speed increase of the V-ribbed belt to prevent slippage of the belt, non-continuous impact of shape said at speed reduction of the V-ribbed belt that allows sliding in the opposite direction of the running direction of the belt Kiga, resin pulley, characterized by being formed with a plurality of circumferentially.

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