JP2006189104A - Spring clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spring clutch in which part of a coil spring is prevented from entering a gap in an axial direction between an input side member and an output side member even if a spring material has a thin thickness in the axial direction. <P>SOLUTION: In the spring clutch, a pulley hub 1 is arranged coaxially with a pulley 2, torque transmitting surfaces 6, 8 comprising circular cylindrical surfaces are formed in both members, and the coil spring 10 straddling the torque transmitting surfaces 6, 8 of the two members are installed. A radial gap G is formed between the ends 10a, 10b of the coil spring 10 in the axial direction and the torque transmitting surfaces 6, 8, an annular torque transmitting member 20 are interposed in the radial gap G straddling the transmitting surfaces 6, 8 of the two ends. The torque transmitting member 20 is expanded radially by expansion of the diameter between the ends 10a and 10b of the coil spring 10, and thus is brought into press contact with the torque transmitting surfaces 6, 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a spring clutch that transmits rotation of an input side member to an output side member and blocks transmission of rotation from the output side member to the input side member.

  In general, in an internal combustion engine, rotation of an engine crankshaft is transmitted to a rotation shaft of an engine auxiliary machine such as an alternator by a belt transmission to drive the engine auxiliary machine.

  In the engine accessory driving apparatus as described above, when the engine is suddenly decelerated, the pulley attached to the rotating shaft of the engine accessory is also suddenly decelerated. However, if the engine accessory is an alternator, the rotating shaft of the alternator has a large inertia force, so the pulley mounted on the rotating shaft tries to keep rotating at a constant speed, and the pulley on the crankshaft and the alternator rotate. A large rotational speed difference is generated between the pulleys on the shaft, and the belt tension increases and the belt tends to be damaged.

  In addition, the crankshaft varies in angular speed during one rotation, and due to the fluctuation in angular speed, slippage occurs between the pulley and the belt on the rotating shaft of the engine accessory, and the belt wears out due to the slippage. The sex will be reduced.

  In order to eliminate such inconvenience, conventionally, as shown in FIG. 4, a pulley hub 42 attached to a rotating shaft 41 such as an alternator, and a pulley 43 attached to the pulley hub 42 so as to be freely rotatable. A spring clutch 40 is provided between the pulley hub 42 and the rotation of the pulley 43, which rotates by contact with the belt, is transmitted from the pulley hub 42 to the rotation shaft via the spring clutch 40, and the rotation speed of the rotation shaft 41 exceeds the rotation speed of the pulley 43. Thus, the transmission of rotation from the rotary shaft 41 to the pulley 42 side is blocked by the action of the spring clutch 40. (Patent Document 1).

  In the spring clutch 40 described in Patent Document 1, torque transmission surfaces 44a and 44b made of cylindrical surfaces having the same inner diameter are formed on the inner circumferences of the pulley hub 42 and the pulley 43, and the outer diameter is the torque transmission surface 44a. , 44b, and a coil spring 45 having a diameter larger than that of the pulley hub 42 and the pulley 43 so as to straddle the torque transmission surfaces 44a and 44b, and when the pulley 43 rotates, the coil spring 45 is expanded to increase the torque transmission surfaces 44a and 44b. The pressure contact engagement force of the coil spring 45 is increased, and the rotation of the pulley 43 is transmitted to the pulley hub 42 via the coil spring 45. When the rotational speed of the pulley hub 42 exceeds the rotational speed of the pulley 43, the diameter of the coil spring 45 is reduced to weaken the contact pressure of the coil spring 45 with respect to the torque transmission surfaces 44a, 44b, and the torque transmission surfaces 44a, 44b and coil A slip is generated between the spring 45 and the spring 45.

JP-A-9-119509

  By the way, when the transmission torque of the spring clutch 40 is increased, a high torque is applied to the coil spring 45. For this reason, it is necessary to increase the contact pressure between the coil spring 45 and the torque transmission surfaces 44 a and 44 b of the pulley 43 and the pulley hub 42. As means for realizing this, it is effective to increase the number of turns of the coil spring 45 by providing a thinner spring material for the coil spring 45 in the axial direction.

  However, when the axial thickness of the spring material is made thin, when a torque is applied to the coil spring 45, a part of the coil spring 45 whose diameter is expanded enters the axial gap 46 between the pulley 43 and the pulley hub 42. The problem arises. In such a state, the portion of the coil spring 45 that faces the axial gap 46 is a place where stress is particularly increased due to the structure of the spring clutch, and thus the coil spring 45 is damaged.

  Accordingly, an object of the present invention is to provide a spring clutch in which a part of a coil spring does not enter an axial gap between an input side member and an output side member even if the axial thickness of the spring material is thin. is there.

  In order to solve the above-mentioned problems, the present invention arranges an output side member coaxially with an input side member, provides a torque transmission surface made of a cylindrical surface on both members, and straddles the torque transmission surface of both members. In a spring clutch incorporating a coil spring, a radial gap is provided between the axial ends of the coil spring and the torque transmission surface, and the radial clearance spans the torque transmission surfaces of both members. An annular torque transmission member is interposed as described above, and this torque transmission member is configured to be in pressure contact with the torque transmission surface by being expanded in the radial direction along with the diameter expansion between the end portions of the coil spring.

  According to the structure of this invention, the said torque transmission member is radial as the edge part of the said coil spring expands between the said torque transmission surface and the edge part of the axial direction of the said coil spring. The coil spring is spread and pressed against the torque transmission surface, and the coil spring is in a torque transmission state via the torque transmission member. At this time, the torque transmission surface and the coil spring are arranged so that the annular torque transmission member straddles the torque transmission surfaces of both members, that is, in a state where the axial clearance between the input side member and the output side member is crossed. It intervenes between. For this reason, even if the axial thickness of the spring material is thin, a part of the coil spring is surely prevented from entering the axial gap between the input side member and the output side member.

  Here, since the torque transmission member is rubbed against the coil spring and the torque transmission surface, durability against wear becomes a problem.

  Therefore, it is preferable that the torque transmission member adopts a configuration in which notches having a shape notched from one end side in the axial direction to the other end side are formed at a plurality of locations in the circumferential direction. According to this configuration, since the notch is formed in the torque transmission member, the torque transmission member can easily spread in the radial direction. For this reason, it becomes possible to increase the thickness of the torque transmission member, and to ensure the durability of the torque transmission member.

  Moreover, it is also preferable that the spring material of the coil spring adopts a configuration in which two corners on the outer diameter side are chamfered in the cross-sectional shape. According to this configuration, as described above, when a torque transmission member provided with a notch and widened is adopted, the spread piece and the coil spring come into contact with each other with an inclination when the diameter is expanded, and the coil Since it is not rubbed by the edge of a spring, wear of a torque transmission member is reduced effectively.

  As described above, according to the present invention, even if the axial thickness of the spring material is thin, a spring clutch is obtained in which a part of the coil spring does not enter the axial gap between the input side member and the output side member. be able to.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a one-way overrunning clutch pulley apparatus (hereinafter referred to as a clutch pulley apparatus) to which a spring clutch according to the present invention is applied. In this clutch pulley apparatus, a pulley hub 1 as an output side member attached to a shaft end portion of a rotating shaft (not shown) and a pulley 2 as an input side member are rotatable by a bearing 3 attached to the pulley hub 1. It is supported on the same axis.

  The pulley hub 1 is prevented from rotating with respect to the rotation shaft, and rotates together with the rotation shaft. A flange 4 is provided at the end of the pulley hub 1, and a cylindrical portion 5 is provided on the flange 4. A cylindrical torque transmission surface 6 and a cylindrical surface 7 having a smaller diameter than the torque transmission surface 6 are formed on the inner periphery of the cylindrical portion 5 continuously in the axial direction.

  On the other hand, the pulley 2 has a ribbed belt (not shown) mounting portion formed on the outer periphery thereof, and rotates by the movement of the ribbed belt. A cylindrical torque transmission surface 8 and a cylindrical surface 9 having a smaller diameter than the torque transmission surface 8 are formed on the inner periphery of the outer end of the pulley 2 in the axial direction. The torque transmission surface 8 formed on the pulley 2 is aligned in the axial direction with respect to the torque transmission surface 6 formed on the pulley hub 1, and the inner diameters of both torque transmission surfaces 6 and 8 are substantially the same. A coil spring 10 is incorporated in the cylindrical surfaces 7 and 9 so as to straddle both torque transmission surfaces 6 and 8.

  Here, as shown in FIG. 2A, the coil spring 10 is formed of a spring material having a rectangular cross section and chamfering two corners on the outer diameter side. The coil spring 10 is a right-handed coil spring when the pulley 2 is rotated in the right direction as viewed from the left side of FIG. 2A, and is left-handed when it is rotated in the left direction. A coil spring is used.

  The outer diameter of the coil spring 10 in the natural state is the same diameter in the axial direction, and is larger than the inner diameter of the cylindrical surfaces 7 and 9. In the coil spring 10, the end portions 10 a, 10 b (about 2 turns) in the axial direction are press-fitted into the cylindrical surfaces 7, 9 and are in frictional contact with the cylindrical surfaces 7, 9. . Thus, a radial gap G is provided between the end portions 10a and 10b of the coil spring 10 and the torque transmission surfaces 6 and 8 when the coil spring 10 is in a natural state. An annular torque transmission member 20 is interposed in the radial gap G so as to straddle both torque transmission surfaces 6 and 8.

  As shown in FIG. 3, the torque transmission member 20 is formed in a cylindrical shape, and notches 21 having a shape that is notched from one end side in the axial direction toward the other end side are equally spaced at a plurality of locations in the circumferential direction. It is formed with. In order to prevent the ring part 22 from being torn, the axial one end part 21a of the notch 21 has an arc shape.

  The torque transmission member 20 has an inner diameter surface slightly larger than the outer diameter surface between the end portions 10 a and 10 b of the coil spring 10, and the outer diameter surface is provided with a smaller diameter than both the torque transmission surfaces 6 and 8. . The axial length of the torque transmission member 20 is slightly shorter than between the axial side surfaces of the radial gap G. Thereby, in the non-torque transmission state, the torque transmission member 20 is gently fitted to the outer diameter surface between the end portions 10a and 10b of the coil spring 10, and the radial clearance is not in contact with the torque transmission surfaces 6 and 8. G intervenes.

  For the material of the torque transmission member 20, it is preferable to use an inexpensive material such as a pressed steel plate, for example.

  In the pulley clutch device having the above-described configuration, when the pulley 2 is rotated by contact with the belt when the pulley 2 is stopped, as shown in FIG. 2B, the cylindrical surface 9 and the end portion 10b of the coil spring 10 are connected. The frictional contact pressure increases, and the diameter between the end portions 10a and 10b increases. Accordingly, the torque transmission member 20 spreads in the radial direction and press-contacts both the torque transmission surfaces 6 and 8, and the pressure engagement force with respect to both the torque transmission surfaces 6 and 8 is increased to be in a torque transmission state. Thereby, the rotation of the pulley 2 is transmitted to the pulley hub 1 via the coil spring 10, and the rotation shaft rotates in the same direction as the pulley 2.

  If the rotational speed of the rotating shaft exceeds the rotational speed of the pulley 2 during rotation of the rotating shaft, the frictional contact pressure between the cylindrical surface 7 formed on the pulley hub 1 and the end 10a of the coil spring 10 increases, and both torques The pressure engagement force between the transmission surfaces 6 and 8 is reduced, and the diameter between the end portions 10a and 10b of the coil spring 10 is reduced. Along with this, the torque transmission member 20 is closed from the spread state, and eventually the end portions 10a and 10b of the coil spring 10 are not in contact with the torque transmission surfaces 6 and 8. Thereby, each edge part 10a, 10b of the coil spring 10 will be in a sliding contact state with each cylindrical surface 7 and 9, and it is prevented that rotation of a rotating shaft is transmitted to the pulley 2. FIG.

A longitudinal front view of a spring clutch according to an embodiment (A) is a partially longitudinal front view showing the vicinity of the torque transmission member in the non-torque transmission state of the spring clutch of FIG. 1, and (b) is a partially longitudinal front view showing the torque transmission state of FIG. 1 is an overall perspective view of the torque transmission member of FIG. Longitudinal front view of conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pulley hub 2 Pulley 5 Cylindrical part 6, 8 Torque transmission surface 7, 9 Cylindrical surface 10 Coil spring 10a, 10b End part 20 Torque transmission member 21 Notch 21a One end part 22 Ring part

Claims (3)

  In the spring clutch in which the output side member is disposed on the same axis as the input side member, the torque transmission surface formed of a cylindrical surface is provided on both members, and a coil spring is incorporated so as to straddle the torque transmission surface of both members. A radial gap is provided between the axial ends of the coil spring and the torque transmission surface, and an annular torque transmission member is interposed in the radial gap so as to straddle the torque transmission surfaces of both members. The torque transmission member is brought into pressure contact with the torque transmission surface by being expanded in a radial direction along with an increase in diameter between the end portions of the coil spring.   2. The spring clutch according to claim 1, wherein the torque transmitting member is formed with a plurality of cutouts in a circumferential direction formed by cutting out from one end side in the axial direction toward the other end side.   3. The spring clutch according to claim 1, wherein the spring material of the coil spring is chamfered at two corners on the outer diameter side in a cross-sectional shape thereof.

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