JP2007278364A - Spring clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spring clutch having improved durability by reducing the wear of the surface of the clutch spring and a clutch face. <P>SOLUTION: The clutch spring 17 formed of a sectionally angular wire material is incorporated between a pulley 1 and a pulley hub 2 incorporated inside thereof. The outer periphery of the clutch spring 17 is put in elastic contact with the cylindrical clutch face 16 formed on the inner periphery of the pulley 1. The terminal of a coil portion at one end of the clutch spring 17 is locked to the pulley hub 2. During the rotation of the pulley 1 in one direction, the diameter of the clutch spring 17 is enlarged to increase engaging force on the clutch face 16 so that the rotation of the pulley 1 is transmitted to the pulley hub 2 via the clutch spring 17. A diamond-like carbon coating 18 is formed on one of the clutch face 16 and the outer peripheral face of the clutch spring 17 to improve the wear resistance of a contact portion between the clutch face 16 and the clutch spring 17 which are rotated in sliding contact during the rotation of the pulley 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention transmits the rotation of the input member in one direction to the output member by a clutch spring incorporated between the input member and the output member, and the input member when the rotation speed of the output member exceeds the rotation speed of the input member. The present invention relates to a spring clutch that interrupts transmission of rotation from the motor to the output member.

  In general, in an accessory drive device that transmits the rotation of the crankshaft of the engine to the rotation shaft of the engine accessory by a belt transmission, when the engine is decelerated suddenly, a pulley attached to the rotation shaft of the engine accessory is also included. Try to slow down as well. At this time, if the engine accessory is an alternator, the rotating shaft of the alternator has a large inertial force, so even if the engine is suddenly decelerated, the rotating shaft is not suddenly decelerated, and a pulley mounted on the rotating shaft Tries to keep turning at a constant speed.

  In this case, a large rotational speed difference is generated between the pulley on the crankshaft and the pulley on the rotating shaft of the alternator, and the belt tension increases and the belt is easily damaged.

  Further, the crankshaft changes its angular velocity during one rotation, and slippage occurs between the pulley and the belt due to the fluctuation of the angular velocity, and the belt wears due to the slipping, and durability is lowered.

  Patent Document 1 proposes a clutch pulley device that can eliminate such inconvenience.

  In the clutch pulley apparatus described in Patent Document 1, a clutch spring made of a wire rod having a square cross section is incorporated between a pulley and a pulley hub incorporated inside the pulley, and the outer periphery of the clutch spring is formed on the inner periphery of the pulley. Elastically contact with the cylindrical clutch surface, the coil end of one end of the clutch spring is locked to the pulley hub, and when the pulley rotates in one direction, the clutch spring is enlarged to increase the engagement force with the clutch surface. The rotation of the pulley is transmitted to the pulley hub via the clutch spring.

Further, when the rotation speed of the pulley hub exceeds the rotation speed of the pulley, the clutch spring is reduced in diameter so that slippage occurs at the contact portion between the clutch surface of the pulley and the clutch spring, thereby causing the pulley to rotate freely.
JP 2003-322174 A

  By the way, in the clutch pulley apparatus described in the above-mentioned Patent Document 1, when the pulley is freely rotated, the clutch clutch surface of the pulley and the contact portion between the clutch spring rotate in contact with each other. There is an inconvenience of being easily worn.

  An object of the present invention is to provide a spring clutch that reduces the wear of the surface of the clutch spring and the clutch surface and is excellent in durability.

  In order to solve the above problem, in the present invention, an input member having a cylindrical clutch surface on the inner periphery, an output member incorporated inside the input member and supported relatively rotatably, The clutch member includes a clutch spring which is assembled between the input member and the output member, and one end portion is locked to the output member, and an outer peripheral surface thereof is elastically contacted with the clutch surface. In the spring clutch in which the clutch spring is expanded by contact with the input member to transmit rotational torque from the input member to the output member, a diamond-like carbon film is applied to at least one of the clutch surface of the input member and the outer peripheral surface of the clutch spring. The formed structure was adopted.

  As described above, by forming a diamond-like carbon film on at least one of the clutch surface formed on the input member and the outer peripheral surface of the clutch spring, the diamond-like carbon film is extremely smooth and very hard. At the time of free rotation of the input member, it is possible to improve the wear resistance of the contact portion between the clutch surface and the clutch spring that rotate while contacting, and a spring clutch having excellent durability can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, a pulley hub 2 as an output member is relatively rotatably incorporated inside a pulley 1 as an input member.

  The pulley hub 2 includes an output shaft 2a made of metal and a sleeve 2b provided on the outside thereof. The output shaft 2a has small diameter portions 3 and 4 at both ends, and a single seal bearing 5 that rotatably supports the pulley 1 and the pulley hub 2 between the outer periphery of the small diameter portion 3 at one end and the inner periphery of one end portion of the pulley 1. Is incorporated.

  Further, the inner diameter portion of the seal member 6 attached to the inner periphery of the other end of the pulley 1 is in elastic contact with the outer periphery of the small-diameter portion 4 at the other end, and between the seal member 6 and the single seal bearing 5. A grease enclosure space 30 is formed.

  The sleeve 2b is made of a synthetic resin molded product. The sleeve 2b is press-fitted into the outer periphery of the output shaft 2a, and an annular protrusion 7 is formed on the inner periphery of the end portion on the seal member 6 side. The annular protrusion 7 is immovable in the axial direction by a shoulder 8 formed on the outer periphery of the other end of the output shaft 2a and a retaining ring 9 attached to the outer periphery of the small diameter portion 4 of the output shaft 2a.

  Further, a pair of flanges 10 and 11 are formed on the outer periphery of both ends of the sleeve 2b, and a space between the pair of flanges 10 and 11 is a grease reservoir. The pair of flanges 10 and 11 have different outer diameters, and the outer diameter of the large diameter flange 10 on the seal member 6 side is slightly smaller than the inner diameter of the pulley 1, and acts as a clutch spring removal prevention mechanism described later, The outer diameter surface of the large-diameter rod 10 is a radial bearing surface 12 that supports the pulley 1 and the output shaft 2a relatively rotatably.

  The small diameter flange 11 on the side of the single seal bearing 5 is wider than the large diameter flange 10. As shown in FIG. 2, a pair of fitting recesses 13 are formed in the small-diameter flange 11 on the side surface facing the single seal bearing 5 with an interval of 180 °. On the other hand, a pair of protrusions 14a and 14b fitted into the respective fitting recesses 13 are provided at an outer periphery of an end of the output shaft 2a on the side of the single seal bearing 5 with an interval of 180 °. The sleeve 2b is prevented from rotating around the output shaft 2a by the fitting of 14b and the fitting recess 13.

  The pair of projecting portions 14 a and 14 b have different lengths, and the distal end portion of the projecting portion 14 a having a long length is located outward from the outer diameter surface of the small diameter rod 11, and the outer periphery thereof is close to the inner periphery of the pulley 1. ing.

  Further, the outer diameter surface of the small-diameter flange 11 is provided with a notch 15 extending in the circumferential direction from the fitting recess 13 into which the long protruding portion 14a is fitted.

  As shown in FIG. 1, a cylindrical clutch surface 16 is formed between the single seal bearing 5 and the seal member 6 on the inner periphery of the pulley 1, and a clutch spring 17 is provided inside the clutch surface 16. .

  The clutch spring 17 is made of a wire having a square cross section. The clutch spring 17 is naturally larger in diameter than the inner diameter of the clutch surface 16 and is incorporated in the pulley 1 in a reduced state, and the outer peripheral surface is the clutch surface 16. In elastic contact.

  Here, as shown in FIG. 4I, a diamond-like carbon film (hereinafter referred to as a DLC film) 18 is formed on the clutch surface 16 with which the outer peripheral surface of the clutch spring 17 comes into contact. The spring 17 is in elastic contact.

  As shown in FIGS. 1 to 3, a torque transmission projection 19 is locked to a terminal portion of the coil portion 17a at one end of the clutch spring 17, and the torque transmission projection 19 is formed on the outer diameter surface of the sleeve 2b. It fits in the formed notch 15 and opposes the protrusion 14a in the circumferential direction.

  A side surface of the projecting portion 14 a facing the tip surface of the torque transmitting projection 19 is a tapered surface 20, while a tip surface of the projecting portion 19 a of the torque transmitting projection 19 facing the projecting portion 14 a is also tapered to match the tapered surface 20. The surface 21 is used.

  Here, when locking the terminal portion of the clutch spring 17 and the torque transmission projection 19, as shown in FIG. 3, an L-shaped engagement recess 22 is formed on the upper surface of the torque transmission projection 19, An L-shaped engagement piece 23 is provided at the end of the clutch spring 17, and the engagement piece 23 is engaged with the engagement recess 22.

  As shown in FIG. 1, a positioning ring 25 is provided between the single seal bearing 5 and a shoulder 24 formed on the outer periphery of one end of the output shaft 2a. A positioning piece 26 is provided on the outer periphery of the positioning ring 25, and the positioning piece 26 is in contact with the side surface of the torque transmission projection 19. The clutch spring 17 is formed by the positioning piece 26 and the large-diameter flange 10 of the sleeve 2b. Are positioned in the axial direction.

  In the spring clutch having the above-described configuration, when driving the alternator as an engine auxiliary machine, a pulley hub 2 is attached to the rotating shaft of the alternator to prevent rotation, and a belt stretched between the pulley 1 and the pulley on the crankshaft is attached. The rotation of the crankshaft is transmitted to the pulley 1.

  In the use state as described above, when the rotation of the crankshaft is transmitted to the pulley 1 and the pulley 1 rotates in the direction indicated by the arrow in FIG. 2, the clutch spring 17 expands in diameter due to contact with the clutch surface 16, The pressure contact engagement force with respect to the clutch surface 16 increases. At this time, the torque transmission projection 19 at one end of the clutch spring 17 smoothly slides radially outward along the taper surface 20 of the projection 14 a, and the outer peripheral surface of the coil portion 17 a at one end of the clutch spring 17 is While being brought into pressure contact with the clutch surface 16 of the pulley 1, rotational torque is transmitted from the torque transmission projection 19 to the projection 14 a, and the pulley hub 2 rotates in the same direction as the pulley 1.

  As described above, when the rotational torque is transmitted from the pulley 1 to the pulley hub 2, the coil portion 17 a at one end of the clutch spring 17 transmits the rotational torque to the protruding portion 14 a in a state where the outer peripheral surface is in pressure contact with the clutch surface 16. The bent portion is not formed in the coil portion 17a. For this reason, even if transmission and interruption of rotational torque are repeated, the coil portion 17a is not damaged by fatigue, and a spring clutch having excellent durability can be obtained.

  Moreover, since the contact between the protrusion 14a and the torque transmission protrusion 19 is a metal-to-metal contact, wear of the contact surface can be suppressed.

  Furthermore, the wear of the contact surface can be further reduced by improving the surface hardness of the protrusion 14a and the torque transmission protrusion 19 by heat treatment or the like.

  When the rotational speed of the pulley hub 2 exceeds the rotational speed of the pulley 1 in the state of transmission of the rotational torque from the pulley 1 to the pulley hub 2, one end of the clutch spring 17 is engaged by the engagement between the notch 15 and the torque transmission projection 19. The coil portion 17a is dragged, and the coil portion 17a moves inward in the radial direction of the sleeve 2b by its own restoring elasticity, and as shown in FIG. Sliding occurs at the contact portion between the clutch spring 17 and the clutch surface 16, the pulley 1 rotates freely, and the rotation transmission from the pulley 1 to the pulley hub 2 is interrupted.

  Thus, even if the rotational speed of the pulley hub 2 exceeds the rotational speed of the pulley, the torque transmission protrusion 19 is not separated from the protrusion 14a due to the engagement between the notch 15 and the torque transmission protrusion 19. When the rotational speed of the pulley 1 exceeds the rotational speed of the pulley hub 2, the torque transmission projection 19 immediately presses the tapered surface 20 of the projection 14 a and transmits the rotational torque to the pulley hub 2 quickly. be able to.

  Here, when the rotational speed of the pulley hub 2 exceeds the rotational speed of the pulley 1, the outer peripheral surface of the clutch spring 17 rotates in contact with the clutch surface 16 while sliding.

  At this time, since the DLC film 18 is formed on the clutch surface 16 and the DLC film 18 is a very smooth and very hard film, wear generated at the contact portion between the clutch surface 16 and the clutch spring 17 is reduced. Yes6.

  Thus, by providing the DLC film 18 on the clutch surface 16, it is possible to improve the wear resistance of the contact portion between the clutch surface 16 and the clutch spring 17, so that a spring clutch having excellent durability can be obtained. it can.

  In FIG. 4 (I), the DLC film 18 is provided on the clutch surface 16. However, as shown in FIG. 4 (II), the DLC film 18 may be provided on the outer peripheral surface of the clutch spring 17, or FIG. As shown in (III), a DLC film 18 may be provided on each of the clutch surface 16 and the outer peripheral surface of the clutch spring 17.

A longitudinal front view showing an embodiment of a spring clutch according to the present invention Sectional view along the line II-II in FIG. The perspective view which shows the connection part of a clutch spring and a pulley hub (I) is a sectional view showing an enlarged contact portion between the clutch surface and the clutch spring, (II) is a sectional view showing another example of the contact portion between the clutch surface and the clutch spring, and (III) is a clutch surface and the clutch spring. Sectional drawing which shows another example of the contact part of

Explanation of symbols

1 Pulley (input member)
2 Pulley hub (output member)
16 Clutch surface 17 Clutch spring 18 Diamond-like carbon film

Claims (1)

An input member having a cylindrical clutch surface on the inner periphery, an output member incorporated inside the input member and supported relatively rotatably, and one terminal incorporated between the input member and the output member And a clutch spring having an outer peripheral surface elastically contacted with the clutch surface. The input member is configured to expand the diameter of the clutch spring by contact with the clutch surface when the input member rotates in one direction. In the spring clutch designed to transmit the rotational torque to the output member from
A spring clutch characterized in that a diamond-like carbon film is formed on at least one of the clutch surface of the input member and the outer peripheral surface of the clutch spring.

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