JP2007333051A - Spring clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spring clutch capable of preventing the fracture of a clutch spring caused by fatigue. <P>SOLUTION: A cylindrical clutch spring 8 is incorporated between the clutch face 4 of the inner periphery of a pulley 1 and a pulley hub 2 inside the clutch face, an end plate 5 opposed to one end of the clutch spring 8 is disposed on the pulley 1, and an engagement recessed portion 9 composed of an inclined face 9a along the inclined side face 8a of a terminal coil of the clutch spring 8, and an engagement face 9b capable of being engaged with a torque input-side end face 8b is formed on the end plate 5. A flange 7 opposed to the other end of the clutch spring 8 is formed on the pulley hub 2, and an engagement recessed portion 10 composed of an inclined face 10a along the inclined side face 8c of the terminal coil of the clutch spring 8 and an engagement face 10b capable of being engaged with a torque output side end face 8d is formed on the flange 7. The rotation for expanding the clutch spring 8 is transmitted by rotation in one direction of the pulley 1. Thus a folded part is not formed on the clutch spring 8, and the fracture caused by fatigue can be prevented. <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 device described in Patent Document 1, a clutch spring made of a wire having a square cross section is incorporated between the pulley and the pulley hub incorporated inside the pulley, and the outer periphery of the clutch spring is set to the inner periphery of the pulley. The formed cylindrical clutch surface is elastically contacted, and 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, since one terminal portion of the clutch spring is inserted into and locked in the spiral groove formed at the end of the pulley hub, A gap is formed between the clutch surfaces formed on the outer periphery of the coil portion and the inner periphery of the pulley outside the inlet portion.

  For this reason, in the deformation mode of the clutch spring at the time of torque transmission, a bent portion is formed at a position corresponding to the inlet portion of the spiral groove of the clutch spring, and stress at the time of torque input is concentrated on the bent portion. It will be.

  Therefore, when the transmission torque is repeatedly applied, the bent portion may be broken due to fatigue, and there is a point to be improved in improving durability.

  An object of the present invention is to provide a spring clutch with excellent durability that can prevent the clutch spring from being broken by fatigue.

  In order to solve the above-described problems, in the present invention, a cylindrical input member having a cylindrical clutch surface on the inner periphery, and an output member that is incorporated inside the input member and is relatively rotatably supported And a cylindrical clutch spring incorporated between the input member and the output member, and when the relative rotation of the input member with respect to the output member in one direction is increased, the clutch spring is expanded to rotate torque from the input member to the output member. In the spring clutch, a radial clearance is formed between the clutch surface and the outer diameter surface of the clutch spring, and the input member is provided with an end plate facing the one end portion of the clutch spring in the axial direction, A flange facing the other end of the clutch spring in the axial direction is formed on the outer periphery of the output member, a facing surface facing the clutch spring of the end plate, and a clutch spring of the flange A V-shaped engagement recess formed by an inclined surface along the inclined side surface of the terminal coil portion of the clutch spring and an engagement surface with which the end surface of the terminal coil portion can be engaged is formed on each of the facing surfaces facing each other. The configuration was adopted.

  In the present invention, in order to reduce the backlash in the rotational direction at the rotational torque transmission portion, a configuration is adopted in which the engaging recess is formed continuously in the circumferential direction of the end plate and the flange.

  In the spring clutch configured as described above, when the input member rotates in one direction with respect to the output member, the engagement surface of the engagement recess formed in the end plate is connected to one end surface (torque input side end surface) of the clutch spring. Press. At this time, since the other end surface (torque output side end surface) of the clutch spring is engaged with the engagement surface of the engagement recess formed in the flange, the clutch spring expands in diameter and presses against the clutch surface. Thus, the clutch spring rotates together with the input member, and the rotation is transmitted from the torque output side end surface of the clutch spring to the engagement surface of the engagement recess formed in the flange, and the output member rotates in the same direction as the input member.

  As described above, a radial clearance is formed between the clutch surface and the outer diameter surface of the clutch spring, and the end plate provided on the input member is opposed to the clutch spring and the flange provided on the outer periphery of the output member. An engaging recess formed by an inclined surface along the inclined side surface of the terminal coil portion of the clutch spring and an engaging surface with which the end surface of the terminal coil portion can engage is formed on each of the opposing surfaces facing the clutch spring. As a result, the clutch spring is enlarged in diameter by rotation of the input member in one direction with respect to the output member, and rotational torque can be transmitted from the torque output side end surface to the engagement surface of the engagement recess formed in the flange. For this reason, it is not necessary to form a bent portion in the clutch spring when transmitting rotational torque from the clutch spring to the output member, and a bent portion is not formed in the clutch spring during torque transmission. Damage due to fatigue failure of the spring can be prevented.

  In addition, since the clutch spring is expanded in diameter and pressed against the clutch surface, the impact force applied to the clutch spring from the input member can be reduced by expanding the clutch spring until it is pressed into contact with the clutch surface. For this reason, since an impact force is not applied to the clutch spring or the output member, it is possible to effectively prevent damage to these parts, and to smoothly transmit the rotational torque from the input member to the output member. it can.

  Furthermore, a large rotational torque can be transmitted from the clutch spring to the output member by press-engaging the clutch spring to the clutch surface.

  When the rotation speed of the output member exceeds the rotation speed of the input member, the engagement surface formed on the flange separates from the end surface on the torque output side of the clutch spring, and repeats the operation of overcoming the step on the inclined surface. Rotation transmission from to the output member can be cut off.

  Here, when the rotational torque from the input member to the output member is interrupted, the engagement surface of the engagement recess formed on the end plate and the engagement surface of the engagement recess formed on the flange are out of phase in the circumferential direction, Due to the phase shift, the rotational direction between the end surface on the torque input side of the clutch spring and the engagement surface on the end plate side or between the end surface on the torque output side of the clutch spring and the engagement surface on the flange side is reduced. An interval is formed, and the interval becomes a backlash in the rotation direction when the rotation is transmitted from the input member to the output member, and the rotation of the input member cannot be immediately transmitted to the output member.

  For this reason, by forming the engagement recess continuously in the circumferential direction of the end plate and the flange, the engagement surface of the engagement recess formed in the end plate and the engagement surface of the engagement recess formed in the flange When the phase is shifted in the circumferential direction, the end portion of one terminal coil portion of the clutch spring is fitted into the next engagement recess, so that the play in the rotational direction can be reduced.

  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 incorporated inside a pulley 1 as an input member, and the pulley hub 2 and the pulley 1 are relatively rotatable by a bearing 3 incorporated between one end portions. It is supported.

  A cylindrical clutch surface 4 is formed on the inner periphery of the pulley 1. An end plate 5 is formed at the other end of the pulley 1, and a slide bearing 6 is attached to the inner periphery of the end plate 5 to rotatably support the other end of the pulley hub 2. On the other hand, on the outer periphery of the pulley hub 2, a flange 7 is provided at one end close to the bearing 3, and a clutch spring 8 is incorporated between the clutch surface 4 and the pulley hub 2 between the flange 7 and the end plate 5. .

  The clutch spring 8 is formed of a wire having a square cross section and is cylindrical. The outer diameter in the natural state is smaller than the inner diameter of the clutch surface 4, and a radial clearance δ is formed between the clutch spring 4. .

  As shown in FIGS. 1, 3, and 4, a plurality of engagement recesses 9 are continuously formed in the circumferential direction on the surface of the end plate 5 formed on the pulley 1 facing the clutch spring 8. The engagement recess 9 is formed by an inclined surface 9a along the inclined side surface 8a of the terminal coil portion of the clutch spring 8 and an engagement surface 9b with which the torque input side end surface 8b of the terminal coil portion can be engaged. It is shaped.

  As shown in FIGS. 1, 2, and 4, a plurality of engaging recesses 10 are continuously formed in the circumferential direction on the surface of the flange 7 formed on the pulley hub 2 facing the clutch spring 8. The engagement recess 10 is formed by an inclined surface 10a along the inclined side surface 8c of the terminal coil portion of the clutch spring 8 and an engagement surface 10b with which the torque output side end surface 8d of the terminal coil portion can be engaged. It is shaped.

  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. 3, the engagement surface 9 b of the engagement recess 9 formed in the end plate 5. Presses the end surface 8b of the clutch spring 8 on the torque input side.

  At this time, since the torque output side end surface 8d of the clutch spring 8 is engaged with the engagement surface 10b of the engagement recess 10 formed in the flange 7, the clutch spring 8 is expanded in diameter, and the clutch spring is expanded by the increased diameter. The entire outer periphery of 8 contacts the clutch surface 4.

  Further, due to the diameter expansion of the clutch spring 8, the pressure contact engagement force with respect to the clutch surface 4 increases, the clutch spring 8 rotates integrally with the pulley 1, and is formed on the flange 7 from the torque output side end surface 8 d of the clutch spring 8. Rotational torque is transmitted to the engagement surface 10 b of the engagement recess 10, 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 clutch spring 8 expands in diameter, and the outer periphery is formed on the flange 7 from the end surface 8 d on the torque output side in a state of being pressed against the clutch surface 4. Since it is transmitted to the engaging surface 10b of the engaging recess 10,
A bent portion is not formed in the clutch spring 8. For this reason, the clutch spring 8 is not damaged by fatigue failure, and a spring clutch having excellent durability can be obtained.

  Further, since the clutch spring 8 expands in diameter and presses against the clutch surface 4, the impact force applied from the pulley 1 to the clutch spring 8 can be alleviated by increasing the diameter of the clutch spring 8 until it presses against the clutch surface 4. it can. For this reason, since an impact force is not applied to the clutch spring 8 or the pulley hub 2, it is possible to prevent damage to these parts, and to smoothly transmit the rotational torque from the pulley 1 to the pulley hub 2. Can do.

  Further, when the clutch spring 8 is press-engaged and engaged with the clutch surface 4, a large rotational torque can be transmitted from the clutch spring 8 to the pulley hub 2.

  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, the engagement surface 10b of the engagement recess 10 formed in the flange 7 causes the torque output of the clutch spring. The rotation transmission from the pulley 1 to the pulley hub 2 is interrupted by repeating the operation of moving away from the side end surface 8d and overcoming the step on the inclined surface.

  Here, when the rotational torque from the pulley 1 to the pulley hub 2 is interrupted, the engaging surface 9b of the engaging recess 9 formed in the end plate 5 and the engaging surface 10b of the engaging recess 10 formed in the flange 7 are circumferential. The phase shifts in the direction, and due to the phase shift, between the torque input side end surface 8b of the clutch spring 8 and the engagement surface 9b on the end plate 5 side or the torque output side end surface 8d of the clutch spring 8 and the flange The space | interval of a rotation direction is formed between the engaging surfaces 10b of 7 side. The interval becomes a backlash in the rotational direction when the rotation is transmitted from the pulley 1 to the pulley hub 2, and the rotation of the pulley 1 cannot be immediately transmitted to the pulley hub 2.

  As shown in the embodiment, a plurality of engaging recesses 9 and 10 are continuously formed in each of the end plate 5 and the flange 7 in the circumferential direction, thereby engaging the engaging recess 9 formed in the end plate 5. When the phase of the engagement surface 10b of the engagement recess 10 formed on the mating surface 9b and the flange 7 is greatly shifted in the circumferential direction, one of the torque input side end surface 8b and the torque output side end surface 8d of the clutch spring 8 is It will be fitted into the next engaging recess. As a result, the play in the rotational direction can be reduced, and the rotation of the pulley 1 can be immediately transmitted to the pulley hub 2.

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. Sectional view along line III-III in FIG. Exploded perspective view showing part of pulley and pulley hub and clutch spring

Explanation of symbols

1 Pulley (input member)
2 Pulley hub (output member)
4 Clutch surface 5 End plate 7 Flange 8 Clutch spring 8a Inclined side surface 8b Torque input side end surface 8c Inclined side surface 8d Torque output side end surface 9 Engaging recess 9a Inclined surface 9b Engaging surface 10 Engaging recess 10a Inclined surface 10b Engagement surface

Claims (2)

A cylindrical input member having a cylindrical clutch surface on the inner periphery, an output member incorporated inside the input member and supported relatively rotatably, and incorporated between the input member and the output member A spring clutch comprising a cylindrical clutch spring, wherein the clutch spring is expanded in diameter in one direction relative to the output member to transmit a rotational torque from the input member to the output member;
A radial clearance is formed between the clutch surface and the outer diameter surface of the clutch spring, the input member is provided with an end plate facing the one end portion of the clutch spring in the axial direction, and the outer periphery of the output member is provided with the clutch spring. A flange facing the other end portion in the axial direction is formed, and an inclined side surface of the terminal coil portion of the clutch spring is formed on each of the facing surface facing the clutch spring of the end plate and the facing surface facing the clutch spring of the flange. A spring clutch characterized in that a V-shaped engagement recess formed by an inclined surface along the edge and an engagement surface with which an end surface of the terminal coil portion can be engaged is formed.   The spring clutch according to claim 1, wherein the engaging recess is formed continuously in a circumferential direction of the end plate and the flange.

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