JP5741807B2 - Pulley - Google Patents

Description

  The present invention relates to a pulley used in a belt transmission mechanism that transmits a rotational driving force by, for example, an internal combustion engine.

  Conventionally, as a pulley constituting a belt transmission mechanism for transmitting the rotational driving force of a crankshaft of an internal combustion engine such as an automobile to an auxiliary machine of the internal combustion engine, such as an alternator or a water pump, for example, as shown in FIG. It has been known.

  The pulley (damper pulley) 100 is disposed concentrically on the outer peripheral side of a metal disc-shaped hub 101 attached to the shaft end of a crankshaft (not shown) of the internal combustion engine, and is arranged on the outer peripheral surface in the circumferential direction. An annular pulley body 102 made of metal in which a plurality of continuous V grooves (poly V grooves) 102 a are formed, and a rubber-like elastic material (rubber material or rubber-like elasticity) that elastically connects the hub 101 and the pulley body 102. And an elastic body 103 made of a synthetic resin material). As shown in FIG. 10, an endless transmission belt 200 having a plurality of ribs 201 having a cross-sectional shape corresponding to a plurality of V grooves 102a formed on the outer peripheral surface of the pulley body 102 passes through the pulley of the auxiliary machine. The belt transmission mechanism is configured by being wound around the pulley main body 102, that is, the rotational driving force of the internal combustion engine is transmitted to the auxiliary machine via the transmission belt 200.

  In the pulley 100, the natural frequency of the torsional direction of the spring-mass system (sub-vibration system) composed of the pulley body 102 and the elastic body 103 is set in a frequency range in which the torsion angle of the crankshaft is maximized. Therefore, the spring-mass system (sub vibration system) composed of the pulley body 102 and the elastic body 103 resonates in a predetermined rotational speed range where the torsion angle of the crankshaft is maximum, and the vibration displacement in the torsion direction is the input vibration. And exhibiting a dynamic vibration absorption effect (see, for example, Patent Document 1 below).

  However, in the conventional pulley 100, as shown in FIG. 10, the V grooves 102a, 102a,... Have a simple V shape with conical inclined surfaces facing each other. The generation of abnormal noise becomes noticeable due to the misalignment of the pulley 100 and the transmission belt 200 due to the relative axial displacement of the pulley 100 and the relative inclination of the shaft centers of the pulley 100 and the accessory pulley. There's a problem.

  Specifically, if there is a misalignment as described above, the rib 201 of the transmission belt 200 is formed in the V groove of the pulley 100 (pulley main body 102) as shown in FIG. In the process of being bitten deeply from the initial biting position in the misalignment state as in (A) or (B) when biting into the 102a, the rib 201 is continuously on the inner surface of the V groove 102a. The stick-slip is generated by rubbing, and the stick-slip period coincides with the natural vibration period of the end of the transmission belt 200 in contact with the pulley body 102 or the natural vibration period of the pulley body 102. It resonates and generates abnormal noise.

  As a countermeasure against such abnormal noise, a method of reducing the friction coefficient between the transmission belt 200 and the pulley 100 by improving the self-lubricating property of the transmission belt 200 is generally used. However, the original function of the transmission belt 200 is to transmit the driving torque. If the friction coefficient is reduced, slippage is likely to occur between the V-groove 102a and the rib 201 and the torque transmission force is impaired. The coefficient needs to be set and managed severely, and the noise suppression effect due to the reduction of the friction coefficient may be gradually lost due to changes over time.

JP 2003-166593 A

  The present invention has been made in view of the above points, and its technical problem is that an abnormal noise occurs when the rib of the transmission belt is bitten into the V groove of the pulley as the pulley rotates. It is an object of the present invention to provide a pulley that can effectively suppress the occurrence of the above.

As a means for effectively solving the technical problem described above, a pulley according to the present invention is a pulley in which a V groove into which a rib formed on a transmission belt is bitten is formed on an outer peripheral surface. The inner surface is characterized in that the angle of inclination with respect to the plane perpendicular to the axial center changes continuously in the groove depth direction, and forms a curved surface with a concave surface and a raised surface that are continuous in the circumferential direction. It is.

When the rib of the transmission belt is bitten into the V groove of the pulley as the pulley rotates, the vibration force caused by stick-slip caused by the rib rubbing against the inner surface of the V groove is extremely small. . For this reason, in order to reach resonance by the stick-slip excitation force, the natural frequency of the transmission belt or the stick-slip having a period that matches the natural frequency of the pulley needs to be continued for a certain time or more. However, according to the pulley according to the present invention, the inner surface of the V-groove continuously changes in the groove depth direction with respect to the plane perpendicular to the axial center, and the concave surface and the raised surface continue in the circumferential direction. In order to form a wave-like undulating curved surface, the contact angle between the rib and the inner surface of the V-groove changes continuously in the course of the rib being bitten into the V-groove, thereby the stick. -The slip period also changes continuously. For this reason, even if the stick-slip frequency temporarily coincides with the natural frequency of the end of the transmission belt or the natural frequency of the pulley body, resonance hardly occurs and abnormal noise is generated. Absent.

According to the pulley according to the present invention, the inner surface of the V groove changes in the inclination angle with respect to the plane orthogonal to the axis continuously in the groove depth direction, and is a wavy shape composed of a concave surface and a raised surface continuous in the circumferential direction. By making the curved surface undulate, the period of stick-slip caused by the rib of the transmission belt rubbing against the inner surface of the pulley V-groove changes continuously, so that the generation of noise due to resonance is effectively suppressed. be able to.

1 is a perspective view showing a first embodiment of a pulley according to the present invention. It is sectional drawing which cut | disconnects and shows 1st embodiment of the pulley which concerns on this invention by the plane which passes along the axis O. It is a partial external view which shows the shape of the V groove by 1st embodiment of the pulley which concerns on this invention. It is a principal part expanded sectional view which shows the shape of the V groove by 1st embodiment of the pulley which concerns on this invention. In 1st embodiment of the pulley which concerns on this invention, it is explanatory drawing which shows the process in which the rib of a transmission belt is bitten by the V groove | channel of a pulley in the misalignment state. It is a partial external view which shows the shape of the V groove by 2nd embodiment of the pulley which concerns on this invention. It is a principal part expanded sectional view which shows the shape of the V-groove by 2nd embodiment of the pulley which concerns on this invention. In 2nd Embodiment of the pulley which concerns on this invention, it is explanatory drawing which shows the process in which the rib of a transmission belt is bitten by the V groove of a pulley in the misalignment state. It is sectional drawing which cuts and shows an example of the pulley which concerns on a prior art by the plane which passes along the axis O. It is a partial external view which shows the shape of the V groove of the pulley which concerns on a prior art. In the pulley which concerns on the prior art, it is explanatory drawing which shows the process in which the rib of a transmission belt is bitten in the V groove | channel of a pulley in the misalignment state.

  Hereinafter, preferred embodiments of a pulley according to the present invention will be described with reference to the drawings. 1 to 5 show a first embodiment.

  1 and 2, a pulley (damper pulley) 1 includes a metal disc-shaped hub 11 attached to a shaft end of a crankshaft (not shown) of an internal combustion engine in a central shaft hole 11a, and a rim portion 11b thereof. A metal annular pulley body 12 having a plurality of V-grooves (poly-V-grooves) 121 formed concentrically on the outer circumferential side and continuous in the circumferential direction on the outer circumferential surface, and a rim portion 11 b of the hub 11. A rubber-like elastic material (rubber material or a synthetic resin material having rubber-like elasticity) is interposed between the outer peripheral surface and the inner peripheral surface of the pulley body 12 and elastically connects the hub 11 and the pulley body 12. An annular elastic body 13 is provided.

  In the pulley 1, a spring-mass system (sub-vibration system) is configured by the pulley body 12 and the elastic body 13. The torsional direction natural frequency of the spring-mass system is the inertial mass of the pulley body 12 and the elastic body. By the spring constant of 13, the crankshaft is tuned to a predetermined frequency range in which the torsion angle of the crankshaft is maximized, in other words, in the torsional direction natural frequency range of the crankshaft.

  On the outer peripheral surface of the pulley body 12, a plurality of belts are continuously formed in the moving direction on the inner surface of the transmission belt 2 as shown in FIG. A plurality of V-grooves 121 that can be engaged with the chevron rib 2a are formed.

The plurality of V-grooves 121 formed on the outer peripheral surface of the pulley body 12 each have a cross-sectional shape passing through the axial center and corresponding to the rib 2a of the transmission belt 2 to form a generally V-shape. As shown in FIGS. 3 and 4, 122 has a curved surface undulating in a gentle wave shape. Specifically, a pair of inner surfaces 122 of the V grooves 121, the inclination angle with respect to a plane perpendicular to the axis is continuously changed to the groove depth direction as indicated by theta ₁ through? ₄ in FIG. 4 (theta ₁ <Θ ₂ > θ ₃ <θ ₄ ), thereby having gentle concave surfaces 122a and 122c and a gentle raised surface 122b therebetween.

  In the pulley 1 according to the first embodiment configured as described above, the transmission belt 2 is wound around the pulley body 12 around the outer peripheral surface of the pulley body 12 via a pulley of an auxiliary machine (not shown). Thus, a belt transmission mechanism is configured, that is, the rotational driving force of the internal combustion engine is transmitted to the auxiliary machine via the transmission belt 2.

  The internal combustion engine is driven while repeating the steps of intake, compression, explosion (expansion) and exhaust, and the reciprocating motion of the piston is converted into the rotational motion of the crankshaft. Torsional vibration (vibration in the rotational direction) occurs with rotation. When the torsional vibration input from the crankshaft to the hub 11 of the pulley 1 reaches a frequency range where the amplitude of the crankshaft becomes a maximum (a natural frequency range in the torsional direction of the crankshaft), the pulley body 12 and the elastic body 13. Since the spring-mass system configured by oscillates with a vibration waveform in the opposite phase to the input vibration, that is, the torque generated by the resonance occurs in the opposite direction to the torque of the input vibration, effectively reducing the peak of the torsional vibration of the crankshaft. Demonstrate dynamic vibration absorption effect (dynamic damper effect).

  Here, when there is a misalignment between the pulley 1 and the transmission belt 2 due to a relative axial shift between the pulley 1 and the auxiliary pulley, or a relative inclination of the shaft center of the pulley 1 and the auxiliary pulley. When the rotation of the pulley 1 and the travel of the transmission belt 2 associated therewith, as shown in FIG. 5, when the rib 2a of the transmission belt 2 is bitten into the V groove 121 of the pulley 1 (pulley body 12), (A ) Or (B) in the process of being deeply bitten from the initial biting position in the misalignment state, the rib 2a continuously rubs against the inner side surface 122 of the V-groove 121 to cause stick-slip. become.

  However, according to the pulley 1 of the first embodiment, the V-groove 121 of the pulley body 12 has a curved surface in which the inner side surface 122 is gently waved, and the concave surfaces 122a and 122c and the gently raised surface therebetween. Since the rib 2a of the transmission belt 2 is bitten deeper from the initial biting position shown in FIG. 5 (A) or (B), the contact angle of the rib 2a with the inner side surface 122 is continuous. Changes. For this reason, the stick-slip cycle generated when the rib 2a continuously rubs against the inner surface 122 of the V-groove 121 also changes continuously. Since the excitation force due to the stick-slip is extremely small, the stick-slip frequency temporarily matches the natural frequency of the end of the transmission belt 2 and the natural frequency of the pulley body 12. Even if it happens, it will deviate from the natural frequency immediately, so that no abnormal noise is generated due to resonance.

  Further, the undulation of the inner side surface 122 of the V groove 121 is gentle, and with respect to the average angle of the inner side surface 122 with respect to the plane orthogonal to the axis (the angle of the reference conical surface indicated by the alternate long and short dash line in FIG. 4), The angle formed by the tangent lines of the concave surfaces 122a and 122c and the raised surface 122b is preferably about ± 10 degrees, and at most about ± 20 degrees, so that the biting of the rib 2a of the transmission belt 2 is not hindered. .

  From the state in which the rib 2a is deeply bitten into the V-groove 121, the biting becomes shallow as the pulley 1 rotates and the transmission belt 2 travels along with the rotation, and the rib 2a moves away from the V-groove 121 as well. It is.

  Therefore, according to the first embodiment, it is possible to effectively suppress the generation of noise due to the rib 2a of the transmission belt 2 rubbing against the inner side surface 122 of the V groove 121 of the pulley body 12.

  Next, FIGS. 6 to 8 show a second embodiment of the pulley according to the present invention.

In the pulley 1 according to the second embodiment, the difference from the first embodiment described above is that the cross-sectional shape of the plurality of V grooves 121 formed on the outer peripheral surface of the pulley body 12 is generally a parabolic concave surface. That is, the pair of inner side surfaces 122 of each V-groove 121 has an inclination angle with respect to a plane orthogonal to the axis continuously increasing in the groove depth direction as indicated by θ ₁ to θ ₄ in FIG. ₁ <θ ₂ <θ ₃ <θ ₄ ). Other parts can be configured in the same manner as in the first embodiment.

  Also in this embodiment, the tangent line of the inner surface 122 forms the average angle of the inner surface 122 of the V-groove 121 with respect to the plane orthogonal to the axis (the angle of the reference conical surface indicated by the one-dot chain line in FIG. 7). The angle is preferably about ± 10 degrees and at most about ± 20 degrees.

  Therefore, also in the pulley 1 of the second embodiment, the rib 2a of the transmission belt 2 is bitten deeper from the initial biting position in the misalignment state shown in FIG. 8A or 8B. In the process, the contact angle of the rib 2a with the inner surface 122 changes continuously. For this reason, the stick-slip cycle generated when the rib 2a continuously rubs against the inner surface 122 of the V-groove 121 also changes continuously. From the state in which the rib 2a is deeply bitten into the V-groove 121, the biting becomes shallow as the pulley 1 rotates and the transmission belt 2 travels along with the rotation, and the rib 2a moves away from the V-groove 121 as well. It is. For this reason, as in the first embodiment, the generation of abnormal noise due to resonance is effectively suppressed.

  Note that the shape of the inner surface 122 of the V-groove 121 is not limited to the illustrated form, and may be a curved surface in which the inclination angle with respect to a plane orthogonal to the axis continuously changes in the groove depth direction. It ’s fine.

  In each of the above-described embodiments, the configuration of the present invention has been described as applied to a damper pulley (torsional damper) having a spring-mass system configuration. However, the present invention also applies to a pulley without a spring-mass system. Can be applied.

DESCRIPTION OF SYMBOLS 1 Pulley 12 Pulley main body 121 V groove 122 Inner side surface 122a, 122c Concave surface 122b Raised surface 2 Transmission belt 2a Rib

Claims (1)

In a pulley having a V-groove in which a rib formed on a transmission belt is bittened on an outer peripheral surface, an inclination angle of the inner surface of the V-groove with respect to a plane perpendicular to the axis is continuous in the groove depth direction. A pulley that changes and forms a curved surface that is undulated in a circumferential direction and includes a concave surface and a raised surface .

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