0001]The present invention relates to a pulley structure with a coil spring.
BACKGROUND
[0002]In the accessory drive unit by the power of the engine of an automobile or the like for driving the auxiliary machine of the alternator or the like, a pulley connected to auxiliary drive shaft, such as an alternator, a belt over pulley multiplied passed to be connected to the crankshaft of the engine is, the torque of the engine through the belt is transferred to the auxiliary machine. In particular, the pulley connected to the alternator drive shaft having a larger inertia than that of other auxiliary devices, for example as described in Patent Document 1, resorbable pulley structures the rotational fluctuation of the crankshaft used.
[0003]
　Pulley structure described in Patent Document 1 includes an outer rotating member having an inner rotating body which can rotate relative to and outside the rotation member provided inside the outer rotary member, a coil spring, the coil spring the diameter or shrink deformation so that the torque between the outer rotor and the inner rotary member is transmitted or cut off. Coil spring of the pulley structure, to prevent slippage of the belt wound around the outer rotating member, the one-way clutch for transmitting or interrupting the torque in one direction between the outer rotor and the inner rotation body (coil functions as a spring clutch).
CITATION
Patent Document
[0004]
Patent Document 1: Japanese Patent 2014-114947 JP
Summary of the Invention
Problems that the Invention is to Solve
[0005]
　In pulley structure comprises a coil spring clutch such as described in Patent Document 1, when the inner rotation body rotates relatively in the forward direction relative to the outer rotary member, a coil spring, the outer rotary member and the inner rotary body each engage and to transmit torque between the outer rotor and inner rotor. On the other hand, when the inner rotation body rotates relatively in the opposite direction to the outer rotating body, a coil spring, slides (slips) in the circumferential direction with respect to the outer rotary member or the inner rotation body, an outer rotor and an inner the disengagement state does not transmit torque between the rotary member. This sliding, in particular, a coil spring and the sliding portion of the outer rotating member or the inner rotating body (hereinafter, "clutch engaging portion") is worn. Moreover, this sliding can be worn portion which slides the clutch engaging portion of the coil spring. When the clutch engaging portion is worn, when the clutch is in the engaged state, that the contact surface pressure between the coil spring and the clutch engaging portion is reduced, the torque transmitted is reduced.
[0006]
　Therefore, to maintain over the function of the clutch-term, to life the pulley structure, during disengagement of the clutch, minimizing the wear of the coil spring and the sliding portion of the clutch engaging portion It is necessary to. In particular, abnormal wear in the clutch engaging portion occurs, the vehicle is a pulley structure is necessary to avoid leading to life before reaching the lifetime. Here, the abnormal wear of the clutch engaging portion of the clutch engaging portion, of distinct concave consecutive to one end one round or more regions and the sliding part from the spring end of the coil spring along the circumferential direction It says that the wear occurs.
[0007]
　In pulley structure comprises a coil spring clutch such as described in Patent Document 1, in order to avoid abnormal wear of the clutch engaging portion is compressed in the axial direction between the outer rotor and the inner rotary body and to stabilize the posture of the coil spring is in a compressed load condition, the moment of force to incline the coil spring in one direction, and prevented from acting on the portion in contact with the clutch engaging portion of the coil spring, it is necessary to keep the surface pressure acting on the coil spring and the sliding portion of the clutch engaging portion uniform.
[0008]
　Here, in order to stabilize the posture of the coil spring, conventionally, for example, as described below, to the surface in contact with the end face of the coil spring of the rotary member and the helical surface, grinding the end faces in the axial direction of the coil spring by a surface perpendicular to the axial direction of the coil spring (seating Lab plane), the one end and the other end in the axial direction of the coil spring, respectively, contacting the outer rotary member and the inner rotor and the radial, etc. Although was done, even if adopting these configurations, when disengagement of the clutch, there is the abnormal wear occurs in the clutch engaging portion. That is, to suppress abnormal wear of the clutch engaging portion, it was not enough of these conventional configurations.
[0009]
　An object of the present invention is to provide a pulley structure that can more reliably suppress the wear of the clutch engagement portion.
Means for Solving the Problems
[0010]
　The first pulley structure according to the aspect of the present invention, the center and the outer rotary member cylindrical belt is wound, disposed radially inwardly of the outer rotating member, the same rotation shaft and the outer rotary member and is a coil spring which is compressed in the axial direction along the rotation shaft provided between the inner rotating member relatively rotatable, and the inner rotor and the outer rotating member relative to the outer rotary member as, wherein the coil spring, by deforming torsion enlarged or reduced in diameter direction, engages with the outer rotary member and the inner rotary member, torque between the inner rotor and the outer rotary member convey, by torsionally deformed in the opposite direction as when the transmission of torque, becomes disengaged to slide with the outer rotary member or the inner rotation body, and the inner rotor and the outer rotary member It is configured to block the transmission of torque between the winding of the coil spring Number as a natural number M, which is within the range of [M-0.125] and not more than M.
[0011]
　According to this structure, the posture of the coil spring is stabilized, which is axially compressed between the outer rotor and the inner rotary member, a compressed load condition, the moment of force to incline the coil spring in one direction There can be prevented from acting on the portion in contact with the clutch engaging portion of the coil spring. Therefore, at the time of disengagement of the coil spring (clutch), the surface pressure acting on the coil spring and the slide (slip) portion of the clutch engaging portion is uniform. Thus, as compared with the case where the number of turns of the coil spring is out of the above range can suppress abnormal wear from occurring in the coil spring and the sliding portion of the clutch engaging portion.
[0012]
　Pulley structure according to the second aspect of the present invention, the pulley structure according to the first aspect, the number of turns of the coil spring is in the range of M and above [M-0.069].
[0013]
　If the number of turns of the coil spring and in this range, the posture of the coil spring being compressed in the axial direction between the outer rotor and the inner rotation body further by stable, the coil spring in compression load state moment of force to incline in one direction, can be more reliably prevented from acting on the portion in contact with the clutch engaging portion of the coil spring. Therefore, at the time of disengagement of the coil spring (clutch), the surface pressure acting on the coil spring and the sliding portion of the clutch engaging portion is more reliably uniform. Thus, it is possible to more reliably suppress abnormal wear from occurring in the coil spring and the sliding portion of the clutch engaging portion.
[0014]
　Pulley structure according to a third aspect of the present invention, the pulley structure according to the first or second aspect, the torsional torque of the coil spring when the coil spring is the engagement releasing state, 1N - is set to not more than 10N · m m.
[0015]
　If the torsional torque of the coil spring when the coil spring (clutch) is disengaged is set to zero, is limited to disengagement of the clutch is particular driving running pattern (e.g., at engine start) done without, it becomes many frequently clutch engaging portion and the coil spring slides. In contrast, by setting the torsional torque of the coil spring when the clutch is disengaged as in this embodiment, disengagement of the clutch, limited to a specific operation running pattern (e.g., at engine start) performed by the frequency of the clutch engaging portion and the coil spring slides is reduced. As a result, it can be more effectively suppressed wear of the coil spring and the sliding portion of the clutch engaging portion.
The invention's effect
[0016]
　According to the present invention can suppress abnormal wear from occurring in the coil spring and the sliding portion of the clutch engaging portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017]
[1] Figure 1 is a cross-sectional view of a pulley structure of an embodiment of the present invention.
FIG. 2 is a sectional view taken along line II-II of Figure 1.
FIG. 3 is a sectional view taken along line III-III in FIG.
[4] FIG. 4 is a side view of a coil spring.
FIG. 5 is a pulley structure shown in FIG. 1 is a graph showing the relationship between torsional torque and twist angle of the coil spring.
FIG. 6 is a diagram for explaining the number of turns of the coil spring, the relationship between the number of spring wire overlap, (a) shows the case where the number of turns of the natural number M, (b) the number of turns If slightly less than the natural number M, it shows a case (c) is slightly greater than the natural number M number of turns.
[7] FIG. 7 is a schematic configuration diagram of an engine bench test machine used in the test of Example, Figure (a) is viewed from the axial direction of the pulley structure, (b) is a pulley structure axis it is a view seen from the direction perpendicular to the direction.
FIG. 8 is in the examples and the comparative examples is a graph showing the number of turns of the coil spring, the relationship between the maximum wear depth of the clutch engagement portion.
DESCRIPTION OF THE INVENTION
[0018]
　Hereinafter, a description will be given of a preferred embodiment of the present invention.
[0019]
　Pulley structure 1 of the present embodiment, for example, in an automotive accessory drive system (not shown) is installed in the alternator drive shaft. Incidentally, the pulley structure of the present invention may be installed in the auxiliary machine driving shaft other than the alternator.
[0020]
　As shown in FIGS. 1 to 3, the pulley structure 1, the outer rotary member 2, the inner rotary body 3, the coil spring 4 (hereinafter, sometimes simply referred to as "spring 4 ') and a end cap 5. Hereinafter, describing the left in FIG. 1 forward, rightward as the rear. The end cap 5 is disposed at the front end of the outer rotary member 2 and the inner rotor 3.
[0021]
　Outer rotary member 2 and the inner rotor 3 are both generally cylindrical, with the same rotation axis. The rotation axis of the outer rotating member 2 and the inner rotor 3 is a rotary shaft of the pulley structure 1 (hereinafter, simply referred to as "rotation axis"). Further, the rotation axis direction, simply referred to as "axial direction". The inner rotor 3 is provided inside the outer rotary member 2 is rotatable relative to the outer rotary member 2. The outer peripheral surface of the outer rotating body 2, the belt B is wound.
[0022]
　The inner rotary body 3 has cylindrical body 3a, and the outer cylindrical portion 3b located outside the front end of the cylindrical body 3a. A cylindrical body 3a, is fitted a drive shaft S such as an alternator. Between the outer tube portion 3b and the cylindrical body 3a, the support groove 3c is formed. The outer peripheral surface of the inner peripheral surface and the cylindrical body 3a of the outer tube portion 3b are connected through a groove bottom surface 3d of the support groove 3c.
[0023]
　And the inner surface of the rear end of the outer rotating body 2, between the outer peripheral surface of the cylindrical body 3a, the rolling bearing 6 is interposed. And the inner surface of the front end of the outer rotating body 2, between the outer peripheral surface of the outer tube portion 3b, the sliding bearing 7 is interposed. By bearings 6,7, the outer rotary member 2 and the inner rotor 3 is relatively rotatably coupled.
[0024]
　A space between the inner rotor 3 and the outer rotary member 2, the forward of the rolling bearing 6, space 9 is formed. In the space 9, the spring 4 is accommodated. Space 9, the inner peripheral surface of the inner peripheral surface and the outer cylindrical portion 3b of the outer rotating body 2, is formed between the outer peripheral surface of the cylindrical body 3a. Also, the portion located between the rolling bearings 6 and space 9 of the outer rotary member 2, projecting portions 2c are provided projecting inward in the radial direction.
[0025]
　Inner diameter of the outer rotary member 2 is smaller in two steps toward the rear. The inner peripheral surface of the outer rotating body 2 in the small inner diameter of the inner peripheral surface of the outer rotating body 2 to the pressure contact surface 2a, 2 th of the annular surface 2b of the smallest inner diameter. Inner diameter of the outer rotary member 2 in the contact face 2a is smaller than the inner diameter of the outer tube portion 3b. Inner diameter of the outer rotary member 2 in the annular surface 2b is equal to or greater than the inner diameter of the outer tube portion 3b.
[0026]
　Cylindrical body 3a has an outer diameter is greater at the front end. That the outer peripheral surface of the inner rotor 3 contact surface 3e in this portion.
[0027]
　Spring 4, as shown in FIG. 4, a torsion coil spring formed spring wire (spring wire) by winding (coiling) spirally. The spring 4 is a left-handed (counterclockwise direction from the front end 4a to the rear end 4g). The number of turns of the spring 4, the M natural numbers as (e.g. about 5-9) is in the range of [M-0.125] or more and M, more preferably, [M-0.069] or more and M it is within the scope of the following. Here, the number of turns of the spring 4, the angle wound of spring wire which means how many times the 360 ​​°. When the number of turns of the spring 4 is a natural number M, the angle to be wound of spring wire is M times the 360 ​​°, the number of overlapping spring wire regardless of the circumferential position of the spring 4 is a natural number M. On the other hand, if the number of turns of the spring 4 is slightly less or more than the natural number, in most of the spring 4, the number K of overlapping spring wire is a natural number M, in a portion of the spring 4, the number of overlapping spring wire K is [M-1] or one more than the natural number M [M + 1] one less than the natural number M.
[0028]
　Spring 4, in a state where no external force is applied, a diameter over the entire length is constant. The outer diameter of the spring 4 in a state where no external force is applied is greater than the inner diameter of the outer rotary member 2 in the contact face 2a. Spring 4, with the rear end region 4c has a reduced diameter, is accommodated in the space 9. The outer peripheral surface of the rear end region 4c of the spring 4, by the self elastic restoring force of the enlarged diameter direction of the spring 4, is pressed against the contact face 2a. Rear end region 4c is an area of ​​more than one turn from the rear end 4g of the spring 4 (360 ° or more around the rotation axis). For example, if the number of windings of the spring 4 is 7 turns (M = 7), the rear end region 4c is an area of ​​up to about 2 weeks from the rear end 4g of the spring 4.
[0029]
　Further, a pulley structure 1 is stopped, in the state in which the outer peripheral surface of the rear end region 4c of the spring 4 is pressed against the contact face 2a by the self elastic restoring force of the enlarged diameter direction of the spring 4, the front end of the spring 4 side regions 4b is in a state of being slightly enlarged in contact with the contact surface 3e. That is, in a state where the pulley structure 1 is stopped, the inner peripheral surface of the front end side region 4b in the spring 4 is pressed against the contact surface 3e. Front end area 4b is an area of ​​one revolution or more from the front end 4a of the spring 4 (360 ° or more around the rotation axis). For example, if the number of windings of the spring 4 is 7 turns (M = 7), the front end side region 4b is an area for the approximately two laps the upper limit from the front end 4a of the spring 4. In a state where external force to the pulley structure 1 is not acting, the spring 4, the diameter over the entire length is substantially constant.
[0030]
　Thus, the outer peripheral surface of the rear end region 4c of the spring 4 is pressed against the contact face 2a, by the inner circumferential surface of the front end region 4b of the spring 4, a configuration which is pressed against the contact surface 3e, the shaft it is possible to stabilize the posture of the spring 4 in a state of being compressed in the direction.
[0031]
　Spring 4, the state in which external force to the pulley structure 1 is not applied (i.e., a state where the pulley structure 1 is stopped) in are compressed in the axial direction, the axial end face of the front end region 4b of the spring 4 ( hereinafter, the circumferential portion (1 lap less the range of half of the front end 4a of) referred to as "front end face 4e") is in contact with the groove bottom surface 3d of the inner rotary body 3, the axial direction of the rear end region 4c of the spring 4 end surface (hereinafter, referred to as "rear end face 4f") circumferential portion of (range from the rear end 4g of about 1/4 laps) is in contact with the front surface 2c1 of the protruding portion 2c of the outer rotary member 2. Axial compressibility of the spring 4 is, for example, about 20%. Incidentally, the axial compressibility of the spring 4, the difference between the axial length of the spring 4 in a state where the natural length and the external force to the pulley structure 1 of the spring 4 is not applied, the natural length of the spring 4 and it is the ratio of.
[0032]
　Further, the front end surface 4e and the rear end face 4f of the spring 4, the seat Labs surface is formed. The seat Labs surface, formed by grinding is performed, a plane perpendicular to the axial direction of the spring 4. Seating Labs surface of the front end surface 4e and the rear end face 4f, respectively, is formed in a range of end 4a of the spring 4, about 1/4 laps from 4g circumferentially (90 °). Thus, by forming the seat Labs surface on the front end surface 4e and the rear end face 4f of the spring 4, the posture of the spring 4 is compressed in the axial direction can be stabilized.
[0033]
　Groove bottom surface 3d is formed in a spiral shape so as to be in contact with the front end surface 4e of the spring 4. A groove bottom surface 3d of the support groove 3c, and the front end surface 4e of the spring 4, apparently, but the whole circumferential direction is in contact, in practice, the machining tolerance of the parts, a gap is formed in a part of the circumferential direction Sometimes. Aim of the gap is zero by the combination of the finished record size in the machining tolerances of the parts, the aim of the gap, which is dimensioned in consideration of the machining tolerances of the parts (nominal dimensions) (e.g., axial clearance value 0.35mm). Clearance is as close as possible that the zero, the spring 4 can be stably torsional deformation. Then, by forming a groove bottom surface 3d on the helical surface, you are possible to stabilize the posture of the spring 4 is compressed in the axial direction between the outer rotating member 2 and the inner rotor and 3. Further, by forming a groove bottom surface 3d on the helical surface by external factors such as vibration, the central axis of the spring 4 is eccentrically and inclined to the axis of rotation of the two rotating bodies, unstable posture of the spring 4 it is possible to suppress the ringing will of the.
[0034]
　On the other hand, the front 2c1 of the protruding portion 2c in order to slide the rear end surface 4f of the spring 4 as described below, does not form the helical surface, has a planar.
[0035]
　As shown in FIG. 2, of the front end area 4b, a position near the second region 4b2 apart 90 ° around the rotation axis from the front end 4a of the spring 4, a portion of the front end 4a side of the second region 4b2 first regions 4b1, the remaining portion of the third region 4b3. The region between the front end region 4b and the rear end region 4c of the spring 4, i.e., a region that does not contact with any of the contact face 2a and the contact surface 3e, and the free portion 4d.
[0036]
　As shown in FIG. 2, the front end portion of the inner rotary body 3, in the circumferential direction of the inner rotor 3 contact surface 3f facing the front end 4a of the spring 4 is formed. The inner circumferential surface of the outer cylindrical portion 3b, the outer peripheral surface opposite to the protrusion 3g of the front end region 4b protrudes radially inward of the outer tube portion 3b is provided. Projections 3g is opposed to the second region 4b2.
[0037]
　Next, the operation of the pulley structure 1.
[0038]
　First, when the rotational speed of the outer rotating body 2 is greater than the rotational speed of the inner rotor 3 (i.e., when the outer rotary member 2 is accelerated) will be described.
[0039]
　In this case, the outer rotary body 2 is relatively rotated in the positive direction relative to the inner rotary body 3 (arrow direction in FIG. 2 and FIG. 3). With the relative rotation of the outer rotating body 2, the rear end region 4c of the spring 4 is moved together with the pressing surface 2a, it rotates relative to the inner rotor 3. Thus, the spring 4 is torsionally deformed in the diameter direction (hereinafter, referred to as "expanded deformation") it is. Pressing force against contact face 2a of the rear end region 4c of the spring 4 increases as the torsion angle of the enlarged diameter direction of the spring 4 is increased. The second region 4b2 is most likely to undergo torsional stress and torsional angle of the enlarged diameter direction of the spring 4 is increased, away from the contact surface 3e. The first region 4b1 and the third region 4b3 is pressed against the contact surface 3e. Substantially simultaneously with the second region 4b2 is separated from the contact surface 3e, or when the twist angle of the diameter expansion direction of the spring 4 is further increased, the outer circumferential surface of the second region 4b2 abuts against the protrusion 3g. By the outer circumferential surface of the second region 4b2 abuts against the protrusion 3g, is restricted diameter deformation of the front side region 4b, torsional stress is dispersed in a portion other than the front end side region 4b of the spring 4, particularly after the spring 4 torsional stress increases acts on the end side region 4c. Thus, the difference between the torsional stress acting on each portion of the spring 4 is reduced, since it is possible to absorb the strain energy throughout the spring 4, thereby preventing localized fatigue failure of the spring 4.
[0040]
　Also, pressure contact force against the contact surface 3e of the third region 4b3 decreases as the twist angle of the enlarged diameter direction of the spring 4 is increased. Substantially simultaneously with the second region 4b2 abuts against the protrusion 3g, or, when the twist angle of the diameter expansion direction of the spring 4 is further increased, the contact pressure to the contact surface 3e of the third region 4b3 becomes substantially zero. The twist angle of the diameter expansion direction of the spring 4 at this time .theta.1 (e.g., θ1 = 3 °) to. When twist angle of the enlarged diameter direction of the spring 4 exceeds .theta.1, third region 4b3, by expanding the diameter deformed, moving away from the contact surface 3e. However, in the vicinity of the boundary between the third region 4b3 and the second region 4b2, rather than the spring 4 is curved (bent), the front end side region 4b is maintained in a circular arc shape. In other words, the front end side region 4b is maintained easily shaped slide relative to the protrusion 3g. Therefore, when the twist angle of the enlarged diameter direction of the spring 4 is torsional stress increases acts on the front end side region 4b becomes large, the front-side region 4b is contact pressure and the first region 4b1 for projection 3g of the second region 4b2 against the pressure contact force against the contact surface 3e, slides in the circumferential direction of the outer rotary member 2 relative to the protrusion 3g and contact surfaces 3e. By the front end 4a of the spring 4 presses the abutment surface 3f, can be reliably transmit torque between the inner rotor 3 and the outer rotary member 2.
[0041]
　Incidentally, twist angle θ1 or more and .theta.2 of the enlarged diameter direction of the spring 4 (e.g., θ2 = 45 °) of less than, the third region 4b3 is on the inner peripheral surface of spaced and the outer cylinder portion 3b from the contact surface 3e not in contact, the second region 4b2 is pressed against the protrusion 3g. Therefore, in this case, as compared with the case twist angle of the enlarged diameter direction of the spring 4 is less than .theta.1, increasing the effective number of turns of the spring 4, the spring constant (slope of a straight line shown in FIG. 4) is small. Further, when the twist angle of the enlarged diameter direction of the spring 4 is .theta.2, that the outer peripheral surface of the free portion 4d of the spring 4 abuts against the annular surface 2b, is restricted further expanded deformation of the spring 4, the outer rotary member 2 and the inner rotor 3 acts lock mechanism to rotate integrally. This can prevent damage due to diameter expansion deformation of the spring 4.
[0042]
　Then, when the rotational speed of the outer rotary member 2 is smaller than the rotational speed of the inner rotor 3 (i.e., when the outer rotary member 2 is decelerated) will be described.
[0043]
　In this case, the outer rotary body 2 is relatively rotated in the reverse direction relative to the inner rotary body 3 (arrow direction opposite to the direction in FIGS. 2 and 3). With the relative rotation of the outer rotating body 2, the rear end region 4c of the spring 4 is moved together with the pressing surface 2a, it rotates relative to the inner rotor 3. Thus, the spring 4 is deformed torsion direction of reducing the diameter (hereinafter, referred to as "shrink deformation"). Diameter direction of the torsion angle of the spring 4 is .theta.3 (e.g., θ3 = 10 °) of less than, pressing force for pressing surface 2a of the rear end region 4c, although twist angle slightly lower than that of the zero , rear end region 4c is pressed against the contact face 2a. Also, pressure contact force against the contact surface 3e of the front end region 4b is twist angle slightly increased as compared with the case of zero. If twist angle of diameter reduction direction of the spring 4 is θ3 above, contact pressure against the contact face 2a of the rear end region 4c becomes substantially zero, periphery of the outer rotary member 2 at the rear side region 4c against contact face 2a slides in the direction. Therefore, no transmitted torque between the inner rotor 3 and the outer rotary member 2 (see FIG. 5).
[0044]
　Here, as shown in FIG. 5, the torsion torque of the spring 4 when the spring 4 the clutch (spring 4) is disengaged (sliding state) by torsional deformation in the diameter direction (hereinafter, "slip and torque Ts "), rather than set to zero, slight shrink deformation in the spring 4 (it is preferable to set the torque that causes the twist angle θ3 more diameter reducing deformation). Specifically, the slip torque Ts is preferably set to be 1N · m or more and 10 N · m or less (e.g., about 3N · m).
[0045]
　By such a torque characteristic, disengagement of the clutch is performed only to a particular operating travel pattern of the rotation speed of the outer rotary member 2 is smaller than the rotational speed of the inner rotor 3 so as to. For example, at the time of engine start, the driving driving pattern as decreased after the rotational speed of the outer rotary member 2 is increased temporarily large. Then, when the rotational speed of the outer rotary member 2 is increased greatly, the rotational speed of the inner rotor 3 torque to the inner rotor 3 from the outer rotary member 2 is transmitted is increased. Thereafter, when the rotation speed of the outer rotary member 2 is lowered, the rotational speed is slower than the inner rotary body 3 is the outer rotary member 2, this time, disengagement of the clutch takes place.
[0046]
　Here, unlike as described above, a case where the slip torque Ts is set to zero. In this case, the disengagement of the clutch is particular driving running pattern (e.g., at engine start) is performed is not limited to. Therefore, the frequency of contact face 2a (the clutch engaging portion) and the spring 4 slides (slips) increases. However, as described above, by setting as is done by limiting the slip torque Ts to the specific operation running pattern, the frequency of the contact face 2a and the spring 4 slides is lowered, pressing surface 2a the wear of the spring 4 and the sliding portion can be suppressed in.
[0047]
　The slip torque Ts is less than 1N · m, performed is not limited to disengagement of the clutch is particular driving running pattern (e.g., at engine start). If the slip torque Ts exceeds 10 N · m, there is a risk that can not disengage the clutch when the engine is started. If the clutch when the engine is started is not disengaged, it is impossible to prevent slippage of the belt B which is wound externally rotating body 2 wound, the worst, the belt B is likely to deviate from the outer rotary member 2.
[0048]
　In this embodiment, pressure of the spring 4 when accommodated between the outer rotating member 2 and the inner rotor 3, the amount to be reduced in diameter the rear end region 4c of the spring 4 (the clutch engagement surface force), the spring 4 to optimize the design values ​​such as the amount of compression in the axial direction (press-contact force in the axial mating surface), by adjusting the sliding resistance between the spring 4 and the outer rotary member 2, slip torque Ts, is set to torsional torque that can cause a slight shrink deformation in the spring 4.
[0049]
　Thus, the spring 4 is a coil spring clutch, which functions as a one-way clutch for transmitting or interrupting the torque in one direction. When the outer rotating body 2 is relatively rotated in the positive direction relative to the inner rotary body 3, a spring 4, engagement with the respective outer rotary member 2 and the inner rotor 3 engaged with the outer rotary member 2 and the inner rotor 3 to transmit torque between the. On the other hand, when the outer rotary member 2 is relatively rotated in the reverse direction relative to the inner rotary body 3, spring 4, the torque between the outer rotating member 2 and the inner rotor 3 slides against contact face 2a It does not transmit.
[0050]
　Here, as a coil spring 4 constituting the pulley structure 1, consider adopting (a) ~ the turns of three different types, as shown in (c) coil spring 4A ~ 4C of FIG. Coil springs 4A is a coil spring of the number of turns of wire natural M (M = 7 in the figure). Coil springs 4B, the number of turns is slightly less coil spring than the natural number M. Coil spring 4C, the number of turns is slightly more coil springs than the natural number M. Incidentally, in FIG. 6 (a) ~ (c) are each a view of a coil spring 4 which left figure seen from the front, a diagram of the coil spring 4 the right figure viewed from the side.
[0051]
　In the coil spring 4A, regardless of the circumferential position, the number K of overlapping spring wire are the same M. Therefore, the coil springs 4A, the compression rigidity regardless of the circumferential position is uniform, the posture of the coil spring 4A compressive load state is stable. Thus, the moment of force to incline the coil spring 4A in one direction, hardly acts on the portion in contact with the contact face 2a of the coil spring 4A (clutch engaging portion). As a result, never the surface pressure from the coil spring 4A is added to the pressure-contact surface 2a is concentrated on a part, is a risk hardly occurs abnormal wear on the contact face 2a.
[0052]
　In the coil spring 4B, in the circumferential direction of the portion, the number K of overlapping spring wire is [M-1], the number K of overlapping spring wire is M in the other parts of the. Therefore, the coil spring 4B is different from the coil spring 4A, the variation of the compressive stiffness due circumferential position increases. However, the coil in the spring 4B also, if the area number K is less overlapping of the spring wire is relatively narrow (for 45 ° or less), wide number K is often the overlapping portions of the spring wire, this portion groove bottom face 3d and to act as thrusting against the projecting portion 2c, the posture of the coil spring 4B compressive load state is relatively stable. Thus, the moment of force to incline the coil spring 4B in one direction, hardly acts on the portion in contact with the contact face 2a of the coil springs 4B. As a result, the surface pressure applied to the contact face 2a is hard to concentrate on a portion of the coil spring 4B, abnormal abrasion is less likely to contact face 2a.
[0053]
　In the coil spring 4C, in the circumferential direction of the portion, the number K of overlapping spring wire [M + 1], the number K of overlapping spring wire is M in the other parts of the. Then, the coil spring 4C, a compressed load state, the number K is often the overlapping portions of the spring wire acts as thrusting against the groove bottom surface 3d and the projecting portion 2c. Therefore, the moment of force to incline the coil spring 4C in one direction acts on the portion contacting the contact face 2a of the coil spring 4C. As a result, focused from the coil spring 4C in surface pressure portion applied to the contact face 2a, there is a possibility that abnormal wear occurs in a portion of the contact face 2a.
[0054]
　For these reasons, the number of turns is slightly less coil spring than the natural number M, or a natural number M 4 (coil springs 4A, 4B) when adopting is slightly turns of wire than the natural number M large coil spring 4 (coil spring 4C ) as compared with the case of employing a when operating the pulley structure 1, abnormal abrasion is less likely to contact face 2a. At this time, the number of turns of the coil spring 4, if within the scope of the following [M-0.125] or more and M, it is possible to more reliably suppress the abnormal wear. Further, at this time, if the winding number of the coil springs 4 [M-0.069] or more and within a range of not less than M, it is possible to more effectively suppress the abnormal wear.
Example
[0055]
　Next, detailed embodiments of the present invention.
[0056]
　
　pulley structure of Example 1 has the same configuration as the pulley structure 1 of the above embodiment, the spring wire of the coil spring (4) is spring oil-tempered wire (JISG3560: 1994 It was compliant). Spring wire is a trapezoidal wire, the inner diameter side axial length, and 3.8 mm, the outer diameter side axial length, and 3.6 mm, radial length was set to 5.0 mm. Number of turns of the coil spring (4) is set to 7 wound (M = 7), the winding direction was left-handed. Axial compressibility of the coil spring (4) was about 20%. Gaps between the spring wire adjacent to each other in the axial direction was set to 0.3 mm. Also, falling strands of the coil spring was 0.7 °. In other words, the outer diameter side portion in the cross section of the spring wire (surface on the outer diameter side) is, the outer diameter reference line parallel to the center axis of the cross-section coil springs of the spring wire, was 0.7 ° inclination.
[0057]
　
　pulley structures of Examples 2-8, except the number of turns of the coil spring, and the same configuration as the pulley structure of Example 1. Coil spring of the second to the eighth embodiment (4), respectively, the coil spring of Example 1, 5 °, 10 °, 20 °, 25 °, 30 °, 40 °, the 45 ° component length It was with less number of turns only be. Thus, for example, the number of turns of the coil spring of Example 1, 45 ° portion of the length by the number of turns less coil spring of Example 8 (4) 6.875 (= 7-0.125) becomes winding, the number of turns of 25 ° portion of the length the number of turns less example 5 of the coil spring (4) is 6.931 (= 7-0.069) winding.
[0058]
　
　pulley structures of Comparative Examples 1 and 2, except a coil spring, and the same configuration as the pulley structure of Example 1. Coil spring of Comparative Example 1 was assumed with many number of turns for the length of 5 ° min the coil spring of Example 1. Thus, the number of turns of the coil spring of Comparative Example 1, a 7.014 vol. The coil spring of Comparative Example 2 was assumed small number of turns for the length of 50 ° min the coil spring of Example 1. Thus, the number of turns of the coil spring of Comparative Example 2 becomes 6.861 vol.
[0059]
　Incidentally, depending on the number of turns of the increase or decrease of the coil spring, also increases or decreases the natural length of the coil spring. Therefore, the compression ratio in the axial direction of the coil spring in a state where the pulley structure is stopped (design value: about 20%) is strictly slightly differs between specimens, but otherwise, affect the evaluation result not of the level to give.
[0060]
　[Evaluation Method]
　The pulley structure of Examples 1-8 and Comparative Examples 1 and 2, in FIG. 7 (a), using the engine bench test machine 200 shown in (b), it was subjected to abrasion resistance test. Engine bench test machine 200, a test device comprising a accessory drive system, a crank pulley 201 attached to the crankshaft 211 of the engine 210, AC pulley 202, a water pump connected to the air conditioning compressor (AC) and a WP pulley 203 connected to the (WP). Pulley structure 100 of Examples 1 to 8 and Comparative Examples 1 and 2, it is connected to the shaft 221 of the alternator (ALT) 220. Further, between the belt span between the crank pulley 201 and the pulley structure 100, auto-tensioner (A / T) 204 is provided. The output of the engine through one of the belt (V-ribbed belt) 250, a crank pulley 201 in the clockwise direction, is transmitted respectively pulley structure 100, WP pulley 203, AC pulley 202, each accessory ( alternator, water pump, air conditioning compressor) is driven. In (b) of FIG. 7, not shown pulley 202, 203 and 204, it shows the connection between the pulley structure 100 and a crank pulley 201 via a belt 250.
[0061]
　Atmospheric temperature 90 ° C., the belt tension 1500 N, repeatedly alternately start and stop the engine, the number of times the engine is started, when it reaches 500,000 times corresponding to the actual vehicle life, the test was terminated. Once per operating time of the engine (the time from start to stop) it was 10 seconds. Note that the ambient temperature is in the actual vehicle, the alternator, the pulley structure is a temperature assuming the temperature of the thermostatic bath surrounding the crank pulley. Further, the rotational speed of the crankshaft during each engine start was varied between 0 ~ 1800 rpm. By repeating the start and stop of the engine, the coil spring is pressed against surface of the outer rotating body (2) (2a) (hereinafter referred to as "clutch engaging portion") are alternately repeated engagement and sliding against.
[0062]
　After the test, to decompose the pulley structure 100 were measured maximum wear depth of the clutch engaging portion (pressing surface). The results are shown in Table 1 and Figure 8 below. If the maximum wear depth of the clutch engaging portion (pressing surface) is more than 0.15 mm, it was evaluated × (the failure). If the maximum wear depth of the clutch engaging portion (pressing surface) is greater than and 0.075mm in 0.15mm or less, a problem Naki level for practical use, was evaluated ○ (pass). Clutch engaging portion below the maximum wear depth of (pressing surface) is 0.075mm in the case of (half following acceptance judgment level 0.15 mm), a problem Naki level capable of withstanding with a sufficient margin for practical use, evaluation ◎ (pass) and the.
[0063]
[Table 1]

[0064]
　The results of the wear tests shown in Table 1 and Figure 8, in order to be able to effectively suppress abnormal wear of the clutch engaging portion, the number of turns of the coil spring, [M-0.125] or more and it was found that it is preferable to be within the scope of the following M (evaluation ◎ ~ ○). Furthermore, it has been found preferable to the number of turns of the coil spring [M-0.069] or more and within the following M (the evaluation ◎).
[0065]
　As described above, as the compression stiffness of the coil spring is circumferentially uniform, the posture of the coil spring under compressive load is stable, in compressive loading conditions, the moment of force to incline the coil spring in one direction but hardly acts on the portion in contact with the clutch engaging portion of the coil spring. Therefore, at the time of disengagement of the clutch, the surface pressure can be maintained uniformly acting on the portion of the coil spring and the sliding of the clutch engagement portion. As a result, at the time of disengagement of the clutch can be prevented from surface pressure applied from the coil spring to a portion of the clutch engaging portion is concentrated. Table 1 and results of the wear test shown in FIG. 8, was intended to support this idea.
[0066]
　Next, a description will be given of a variation of the present embodiment in which various modifications are.
[0067]
　In the above embodiment, the pulley structure, but the outer rotary member 2 has a structure having a contact face 2a of the clutch engagement portion, it is not limited thereto. The pulley structure may include the clutch engaging portion which slides the inner rotary body 3 the spring 4.
[0068]
　Further, in the above-described embodiment, when the spring 4 is deformed twisting direction of reducing the diameter, which had been configured to be disengaged, it is not limited thereto. When the coil spring is deformed torsion diameter direction, may be configured such that the disengaged state by sliding the outer rotating member or the inner rotor.
[0069]
　The present invention in detail, also has been described with reference to specific embodiments, without departing from the spirit and scope of the present invention, it is possible that various changes and modifications will be apparent to those skilled in the art.
　This application, 2017 April 19 filed Japanese Patent Application 2017-082495, and is based on Japanese Patent Application 2018-070956 2018 April 2 filed, the contents of which are incorporated herein by reference.
DESCRIPTION OF SYMBOLS
[0070]
　1 pulley structure
　2 outside the rotary body
　2a pressing surface
　3 within the rotary body
　4 coil spring

WE CLAIM

An outer rotating body cylindrical belt is wound,
　disposed radially inwardly of the outer rotary member, the inner rotating relatively rotatable with respect to the outer rotary member about said outer rotor and same rotary shaft body and,
　provided between the inner rotor and the outer rotary member, and a coil spring which is compressed in the axial direction along the rotary shaft,
　the coil spring is expanded or contracted direction by twisting deformation, engages with said outer rotary member and the inner rotary member, and transmit torque between the inner rotor and the outer rotary member, torsional deformation in the opposite direction as when the transmission of torque by, in a disengagement state to slide with the outer rotary member or the inner rotating body, it is configured to block the transmission of torque between the outer rotor and the inner rotary member,
　the number of turns of the coil spring, the M is a natural number, [M-0.12 ] Or more and is within the following M, pulley structure.
[Requested item 2]
　The number of turns of the coil spring is in the range of and M inclusive [M-0.069], pulley structure according to claim 1.
[Requested item 3]
　The torsion torque of the coil spring is set below 1N · m or more 10 N · m, pulley structure according to claim 1 or 2 when the coil spring is the disengaged state.