JP2008175291A - :pulley and multi-shaft driving device having this pulley - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the increase of deflection by the resonance of a power transmission belt. <P>SOLUTION: The radius of a pulley 1 changes continuously and peaks of the radius change to rotating angles occur at two positions during one revolution. Furthermore, the rotating angles θ1 and θ2 between the peaks are different from each other. As the pulley 1 is rotated, the tension of the belt 20 placed into the pulley 1 changes. This tension change of the belt 20 causes the peaks to the rotation angles to change at least two positions during one revolution. The rotation angles between the peaks are different from each other. On the other hand, in the tension changes of the belt arising from changes of revolutions and the like, rotation angles between peak changes to the rotating angles are equal to each other. Thus, when the tension changes arising from the radius changes of the pulley 1 and the tension changes arising from the revolution changes are synthesized, the tension of the belt 20 changes irregularly. Therefore, resonance can be prevented because the vibrations of the tension changes of the belt 20 do not coincide with the vibrations inherent of the belt 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pulley used in a multi-axis drive device connected to an engine or the like.

  Conventionally, in a multi-axis drive device that is connected to an engine or the like and an auxiliary machine such as a generator is driven via a belt, if the rotational speed of the drive shaft fluctuates periodically due to factors such as the explosion stroke of the engine, the belt The tension of this also varies periodically. Resonance occurs when the frequency of this tension variation matches the natural frequency of the belt, which is characterized by the belt span length, tension and unit weight. At this time, an increase in belt vibration or abnormal noise occurs, and the durability of the belt decreases.

  Therefore, conventionally proposed are multi-shaft drive devices that have an elliptical pulley or an outer periphery of a perfect circle, and an eccentric pulley whose center of rotation is offset from the center of gravity is engaged with the tension side portion of the belt. (For example, see Patent Documents 1 and 2). An elliptical pulley or a perfect circular eccentric pulley has an outer peripheral shape whose radius changes continuously with respect to the rotation angle. Further, the peak of the change in radius with respect to the rotation angle occurs every half rotation in the case of an elliptical pulley, and occurs every rotation in the case of a perfect circular eccentric pulley. Thus, for example, in the case of a four-cylinder engine, when the tension of the belt due to the explosion stroke occurs twice during one rotation of the drive shaft, In the case of a perfect circular eccentric pulley, the belt is wound at the position of the maximum radius at the time of relaxation so that the drive shaft rotates once while the drive shaft rotates once. Install so that it can be hung. As a result, the belt tension is maintained substantially constant, and the vibration of the belt due to resonance is suppressed.

JP-A-62-258109 Japanese Patent No. 6-10893

  However, even if such an elliptical pulley or a perfect circular eccentric pulley is used, it is impossible to make the belt tension completely constant. In addition, the change in radius of an elliptical pulley or a circular eccentric pulley occurs repeatedly every 180 ° rotation, so even if the tension fluctuation is reduced to some extent, the tension relaxation time is every 180 °. It occurs periodically. Therefore, the frequency of the tension fluctuation can sufficiently match the natural frequency of the belt, so that it is difficult to prevent the occurrence of resonance.

  In the present invention, a pulley capable of preventing the frequency of the belt tension fluctuation caused by the rotational fluctuation of the drive shaft from matching the natural frequency of the belt and reliably preventing the belt from resonating, and a multi-axis drive device having the pulley The purpose is to provide.

Means for Solving the Problems and Effects of the Invention

  The pulley according to claim 1 has an outer peripheral shape in which the radius continuously changes and the peak of the change in the radius with respect to the rotation angle is generated at two locations during one rotation, and the two peaks are further provided. The rotation angles are different from each other.

  In the pulley of the present invention, the radius continuously changes with the rotation, so that the tension of the belt wound around the pulley varies. In addition, since the peak of the change in radius with respect to the rotation angle is generated in two places during one rotation, the peak of the change in belt tension is also generated in at least two places during one rotation. Further, since the rotation angles between the peaks of the pulley radius change are different from each other, the rotation angles between the belt tension fluctuation peaks are also different from each other. That is, the belt tension varies irregularly.

  On the other hand, belt tension fluctuations caused by rotational fluctuations and the like have peaks at equal intervals. When the tension fluctuation caused by the change in the radius of the pulley and the tension fluctuation caused by the rotation fluctuation are combined, the tension fluctuates irregularly. For this reason, the frequency of tension fluctuation and the natural frequency of the belt do not match. That is, resonance can be prevented by disturbing the tension fluctuation.

  A pulley according to a second aspect is the pulley according to the first aspect, comprising two large-diameter portions having an arcuate outer peripheral shape, and two small-diameter portions having a curved outer peripheral shape that smoothly connects the two large-diameter portions. A straight line connecting the center of the arc of one of the two large diameter portions and the rotation center intersects with a straight line connecting the center of the arc of the other large diameter portion and the rotation center, and The radii of the two small diameter portions are smaller than the smaller one of the maximum radii of the two large diameter portions.

  The radius of the two small diameter portions is smaller than the smaller maximum radius of the respective maximum radii of the two large diameter portions. Therefore, at the maximum radius of each of the two large diameter portions, a peak of a change in radius with respect to the rotation angle occurs. Accordingly, the peak of the change of the radius with respect to the rotation angle is generated at two places during one rotation. Further, a straight line connecting the center of the arc of one large diameter portion and the rotation center of the two large diameter portions intersects with a straight line connecting the center of the arc of the other large diameter portion and the rotation center. In other words, the rotation center is shifted from the straight line connecting the centers of the arcs of the two large diameter portions. Therefore, the rotation angles between peaks are different from each other. Accordingly, since the tension of the belt wound around the pulley fluctuates irregularly with the rotation of the pulley, it is possible to reliably prevent resonance with a relatively simple outer peripheral shape.

  The pulley according to claim 3 is the pulley according to claim 2, wherein two circles each having the same center and radius as the arc of the two large diameter portions intersect at two points, and each of the two large diameter portions The maximum radius is 1.03 to 1.2 times the larger distance among the distances from the two intersections to the center of rotation.

  If the smaller one of the maximum radii of the two large-diameter parts is small and the change in the radius with respect to the rotation angle is too small, the effect of disturbing the belt tension fluctuation due to rotation fluctuation, etc. will be diminished and resonance will be prevented. Difficult to do. In addition, if the larger maximum radius of each of the two large diameter portions is too large, there is a disadvantage that the rotational balance is deteriorated. Therefore, by setting the maximum radius of each of the two large diameter portions within an appropriate range, it is possible to reliably prevent resonance while maintaining a certain rotational balance.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the rotation angle between the two peaks is 108 to 144 ° and 252 to 216 °.

  If the difference in rotation angle between the peaks is too large, the rotation center is greatly deviated from the center of gravity of the pulley. On the contrary, if the difference in the rotation angle between the peaks is too small, the effect of disturbing the belt tension fluctuation caused by the rotation fluctuation or the like is small, and resonance cannot be prevented. Therefore, by setting the rotation angle between peaks within an appropriate range, it is possible to reliably prevent resonance while maintaining a certain rotation balance.

  The multi-shaft drive device according to claim 5 is a multi-shaft drive device in which a transmission belt is suspended over a plurality of pulleys respectively connected to an engine crankshaft and at least one driven shaft. The connected pulley has a peripheral shape in which the radius continuously changes and the radius change peak with respect to the rotation angle is generated at two locations during one rotation, and the rotation between the two peaks is further performed. It has a pulley characterized by different angles.

  As the pulley connected to the crankshaft rotates, the radius thereof continuously changes, so that the belt tension between the pulley connected to the crankshaft and other pulleys varies. In addition, since the peak of the change in the radius with respect to the rotation angle of the pulley connected to the crankshaft is generated twice during one rotation, and the rotation angle between the peaks is different from each other, the peak of the belt tension change also rotates once. There are at least two places in between, and the rotation angles between the peaks of tension fluctuations are also different from each other. That is, the belt tension between the pulley connected to the crankshaft and the other pulley fluctuates irregularly. Therefore, when the tension fluctuation caused by the change in the radius of the pulley connected to the crankshaft and the tension fluctuation caused by the crankshaft rotation fluctuation are combined, the belt tension fluctuates irregularly. Therefore, the frequency of belt tension fluctuation and the natural frequency of the belt do not match. That is, resonance can be prevented by disturbing fluctuations in belt tension.

  According to a sixth aspect of the present invention, the multi-axis drive device according to the fifth aspect has a pulley characterized in that the rotation angles between the two peaks are 108 to 144 ° and 252 to 216 °.

  By setting the rotation angle between the peaks within an appropriate range, it is possible to reliably prevent resonance while maintaining a certain rotation balance.

  Next, an embodiment of the present invention will be described. As shown in FIG. 1, the multi-axis drive device 100 of the present embodiment includes an engine crankshaft 21, a driven shaft 22 connected to, for example, a water pump, a driven shaft 23 connected to, for example, a generator, Pulleys 1, 24, 25 connected to the shafts 21, 22, 23, respectively, and a transmission belt 20 suspended between these pulleys 1, 24, 25.

  The pulley 1 is attached to the crankshaft 21 of the engine, and rotates in the direction of the arrow in FIG. 1 (clockwise direction). The pulleys 24 and 25 are rotatably supported by the driven shafts 22 and 23, respectively. When the pulley 1 is driven to rotate, the transmission belt 20 is driven by the rotation of the pulley 1, and the pulleys 24 and 25 are driven in the direction indicated by the arrows in FIG. Rotate.

  The transmission belt 20 is preferably a V-ribbed belt having a plurality of V-shaped rib portions extending in the longitudinal direction of the belt on the contact surface side with the pulleys 1, 24, 25.

  Here, in particular, a pulley 1 having a shape capable of preventing the resonance of the belt is employed in a pulley connected to a crankshaft as a drive shaft. As shown in FIG. 2, the pulley 1 of the present embodiment smoothly connects two large-diameter portions 2 and 3 having an arcuate outer peripheral shape, and both ends of the large-diameter portion 2 and the large-diameter portion 3. Two small diameter portions 4 and 5 having a curved outer peripheral shape are provided.

  The maximum radius r2 of the large diameter portion 3 is smaller than the maximum radius r4 of the large diameter portion 2. Further, the radius of the small diameter portion 4 and the radius of the small diameter portion 5 are both smaller than the radius r2. Therefore, as shown in FIG. 3, at the radius r2 and the radius r4, a peak of a change in radius with respect to the rotation angle occurs. That is, two peaks occur during one revolution of the radius change with respect to the rotation angle. In FIG. 2, radii r1 and r3 are the minimum radii of the small diameter portions 4 and 5, respectively.

  The maximum radius r4 of the large diameter portion 2 is a radius that passes through the arc center C2 of the large diameter portion 2, and the maximum radius r2 of the large diameter portion 3 is a radius that passes through the arc center C3 of the large diameter portion 3. The straight line connecting the center C2 of the arc of the large diameter portion 2 and the rotation center C1 and the straight line connecting the center C3 of the arc of the large diameter portion 3 and the rotation center C1 intersect. Therefore, the rotation angles θ1 and θ2 between the peaks are different from each other.

  In FIG. 2, a circle 6 is a circle having the same center and radius as the arc of the large diameter portion 2. The circle 7 is a circle having the same center and radius as the arc of the large diameter portion 3. Circle 6 and circle 7 intersect at two points. The distance L1 is the larger distance of the distances from these two intersections to the rotation center C1.

  In addition, since the outer periphery shape of the pulley 1 is not symmetrical, it is preferable to adjust the rotation balance at the pulley boss portion.

  The crankshaft 21 has a rotational fluctuation due to an explosion stroke of the engine. Therefore, the tension of the belt 20 periodically varies due to this rotational variation.

  Further, the tension of the belt 20 varies as the radius of the pulley 1 continuously changes. At the radius r2 and the radius r4, the peak of the change of the radius with respect to the rotation angle is generated, so the peak of the fluctuation of the tension of the belt 20 is also generated at two places during one rotation. Further, since the rotation angles θ1 and θ2 between the peaks are different from each other, the rotation angles between the peaks of the fluctuation of the tension of the belt 20 with respect to the rotation angle are also different from each other.

  By combining the irregular tension fluctuation caused by the change in the radius of the pulley 1 and the regular tension fluctuation caused by the rotation fluctuation, the tension fluctuation of the belt 20 fluctuates irregularly. Therefore, it is possible to prevent the frequency of the tension fluctuation from matching with the natural frequency of the belt 20. That is, resonance can be prevented by disturbing fluctuations in the tension of the belt 20. Furthermore, it is possible to prevent the generation of abnormal noise and improve the durability of the belt.

  If the radius r2 is small and the peak value of the radius with respect to the rotation angle at the radius r2 is too small, the effect of disturbing the tension fluctuation of the belt 20 becomes thin, and it becomes difficult to prevent resonance. Further, if the radius r4 is too large, there arises a disadvantage that the rotational balance is deteriorated. Therefore, by setting the radius r2 and the radius r4 within appropriate ranges, it is possible to reliably prevent resonance while maintaining a certain rotational balance. Specifically, the radius r2 and the radius r4 are preferably 1.03 to 1.2 times the distance L1.

  If the difference between the rotation angles θ1 and θ2 between the peaks is too large, the rotation center C1 is greatly deviated from the center of gravity of the pulley 1. Therefore, there arises a disadvantage that the rotation balance is deteriorated. Conversely, if the difference between the rotation angles θ1 and θ2 between the peaks is too small, the effect of disturbing the tension variation of the belt 20 is small. Therefore, it becomes difficult to prevent resonance. Therefore, by setting the rotation angles θ1 and θ2 between the peaks within an appropriate range, it is possible to reliably prevent resonance while maintaining a certain rotation balance. Specifically, the rotation angles θ1 and θ2 between the peaks are preferably 108 to 144 ° and 252 to 216 °, respectively.

  Here, in the case of the conventional perfect circular pulley, the tension side of the belt 20 is most tense during the explosion stroke. The pulley 1 is preferably installed so that the tension on the tension side of the belt 20 is minimized in accordance with the tension time. As a result, resonance can be prevented and fluctuations in the tension of the belt 20 at the time of at least one tension during one rotation can be reduced.

  Further, in the case of a conventional perfect circular pulley, the tension side of the belt 20 is most relaxed at a time delayed by 30 to 70 ° from the explosion. In accordance with this relaxation time, the pulley 1 may be installed so that the tension on the tension side of the belt 20 is maximized. As a result, resonance can be prevented and fluctuations in the tension of the belt 20 at the time of at least one relaxation during one rotation can be reduced.

  In order to prevent resonance, the pulley 1 may be connected to a driven shaft. According to this configuration, the transmission belt is driven as the drive pulley rotates, and the pulley 1 is driven to rotate as the transmission belt travels. At this time, as the pulley 1 rotates, the belt tension between the driving pulley and the pulley 1 fluctuates irregularly. When the tension fluctuation caused by the change in the radius of the pulley 1 and the tension fluctuation caused by the engine rotation fluctuation are combined, the belt tension fluctuates irregularly, so that the occurrence of resonance can be prevented.

  Further, in order to prevent resonance, as shown in FIG. 4, a pulley 11 in which the radii of the arcs of the two large diameter portions 2 and 3 are equal to each other may be used. The rotation center C1 is deviated from a straight line connecting the arc center C2 of the large diameter portion 2 and the arc center C3 of the large diameter portion 3. Further, the radius of the small diameter portion 4 is smaller than the maximum radii r4 and r2 of the large diameter portions 2 and 3, and the radius of the small diameter portion 5 is also smaller than the maximum radii r4 and r2 of the large diameter portions 2 and 3. Therefore, the radius of the pulley 11 changes continuously, and two peaks of the change in radius with respect to the rotation angle occur during one rotation. Furthermore, the rotation angles between the peaks are different from each other.

  By appropriately setting the shape and rotation center of the pulley, it is possible to prevent resonance having various vibration characteristics. The outer peripheral shape of the pulley may be a shape combining arbitrary curves. For example, if a pulley having a smooth convex portion is used, it is possible to partially generate a sudden fluctuation in tension. As a result, the period of the tension fluctuation caused by the fluctuation in rotation can be sufficiently disturbed, so that it is possible to reliably prevent the occurrence of resonance. On the other hand, with respect to these pulleys, the pulley 1 can reliably prevent resonance with a relatively simple outer peripheral shape.

It is a figure which shows the multi-axis drive device which concerns on embodiment of this invention. It is a figure which shows the pulley which concerns on embodiment of this invention. It is a graph which shows the change of the radius to the rotation angle of the pulley concerning the embodiment of the present invention. It is a figure which shows the pulley which concerns on other embodiment.

Explanation of symbols

1 Pulley 2, 3 Large diameter portion 4, 5 Small diameter portion C 1 Rotation center θ 1, θ 2 Rotation angle between peaks r 2, r 4 Maximum radius of large diameter portion 20 Transmission belt 21 Crank shaft 22, 23 Drive shaft 24, 25 Pulley 100 Shaft drive

Claims (6)

It has an outer peripheral shape in which the radius changes continuously and the peak of the change in the radius with respect to the rotation angle occurs in two places during one rotation
Further, the pulley is characterized in that rotation angles between the two peaks are different from each other. Two large-diameter portions having an arcuate outer peripheral shape, and two small-diameter portions having a curved outer peripheral shape that smoothly connects the two large-diameter portions,
A straight line connecting the center of the arc of one large diameter portion and the rotation center of the two large diameter portions intersects with a straight line connecting the center of the arc of the other large diameter portion and the rotation center,
2. The pulley according to claim 1, wherein a radius of the two small diameter portions is smaller than a smaller maximum radius of the maximum radii of the two large diameter portions. Two circles each having the same center and radius as the arcs of the two large diameter portions intersect at two points,
The maximum radius of each of the two large-diameter portions is 1.03 to 1.2 times the larger one of the distances from the two intersections to the center of rotation. 2. The pulley according to 2.   The pulley according to any one of claims 1 to 3, wherein a rotation angle between the two peaks is 108 to 144 ° and 252 to 216 °. A multi-axis drive device in which a transmission belt is suspended over a plurality of pulleys respectively connected to an engine crankshaft and at least one driven shaft;
The pulley connected to the crankshaft has an outer peripheral shape in which the radius continuously changes and the peak of the change in the radius with respect to the rotation angle is generated at two locations during one rotation,
Furthermore, the multi-axis drive device having a pulley characterized in that the rotation angles between the two peaks are different from each other.   The multi-axis drive device having a pulley according to claim 5, wherein a rotation angle between the two peaks is 108 to 144 ° and 252 to 216 °.

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